WorldWideScience

Sample records for acfa isotope activation

  1. ACFA 2020 - An FP7 project on active control of flexible fuel efficient aircraft configurations

    Science.gov (United States)

    Maier, R.

    2013-12-01

    This paper gives an overview about the project ACFA 2020 which is funded by the European Commission within the 7th framework program. The acronym ACFA 2020 stands for Active Control for Flexible Aircraft 2020. The project is dealing with the design of highly fuel efficient aircraft configurations and, in particular, on innovative active control concepts with the goal to reduce loads and structural weight. Major focus lays on blended wing body (BWB) aircraft. Blended wing body type aircraft configurations are seen as the most promising future concept to fulfill the so-called ACARE (Advisory Council for Aeronautics Research in Europe) vision 2020 goals in regards to reduce fuel consumption and external noise. The paper discusses in some detail the overall goals and how they are addressed in the workplan. Furthermore, the major achievements of the project are outlined and a short outlook on the remaining work is given.

  2. ACFA and IPAC announce accelerator prizes

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Steve Myers, CERN's Director for Accelerators and Technology. The Asian Committee for Future Accelerators (ACFA) has joined forces with the first International Particle Accelerator Conference, IPAC’10, to award prizes for outstanding work in the field of accelerators. The conference replaces the regional conferences of the Americas, Europe and Asia and will be hosted by the three regions on a rotational basis (see CERN Courier). The ACFA/IPAC’10 Prizes Selection Committee, chaired by Won Namkung of Pohang Accelerator Laboratory, decided on the prizes and the names of the winners at a meeting on 20 January. The awards will be made during IPAC’10, which will be held in Kyoto on 23-28 May. Jie Wei. (Courtesy Tsinghua University.) Steve Myers, Director for Accelerators and Technology at CERN, receives an Achievement Prize for Outstanding Work in the Accelerator Field with no Age Limit “for his numerous outstanding contributions to the design, construction, commissio...

  3. SSA, PCA, TDPSC, ACFA: Useful combination of methods for analysis of short and nonstationary time series

    Energy Technology Data Exchange (ETDEWEB)

    Vitanov, Nikolay K. [Institute of Mechanics, Bulgarian Academy of Sciences, Akad. G. Bonchev Street, Bl. 4, 1113 Sofia (Bulgaria)], E-mail: vitanov@imech.imbm.bas.bg; Sakai, Kenshi [Department of Eco-Regional Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, 183-8509 (Japan); Dimitrova, Zlatinka I. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Blvd. Tzarigradsko Chausee 72, 1784 Sofia (Bulgaria)

    2008-07-15

    Singular spectrum analysis (SSA), principal component analysis (PCA), and autocorrelation function analysis (ACFA) are useful tools for extracting information from time series. But the combination of these methods and the time delay phase space construction (TDPSC) is not much used. In this paper we present the opportunities of this bundle of four methods for analysis of short and nonstationary time series. The basis of our analysis are time series for the piglet prices and production in Japan before and after the Japan government intervention in the agriculture sector aiming at stabilization of the agriculture prices after the oil crisis in 1974. As a comparison we analyse long stationary chaotic time series from the classical Lorenz system. We show that SSA, PCA and TDPSC perfectly recognize the dimension of the Lorenz system only on the basis of time series for one of its three variables. The bundle of four methods leads us to enough information to make the conclusion that the intervention of the Japan government in agriculture sector was very successful and leaded (i) to stabilization of prices; (ii) to a coupling between the prices and production cycles and (iii) to decreasing the dimension of the phase space of price and production fluctuations around the year trend thus making their dynamics more forecastable.

  4. Déficits locomoteurs causés par une atteinte de la voie corticospinale chez les individus ayant une lésion incomplète de la moelle épinière. Colloque de l’ACFAS (Association canadienne française pour l’avancement des sciences),

    DEFF Research Database (Denmark)

    Barthlemy, D; Willerslev-Olsen, Maria; Biering-Sørensen, Fin;

    2011-01-01

    Montréal, Canada. *in english ACFAS means french canadian association for the advancement of sciences......Montréal, Canada. *in english ACFAS means french canadian association for the advancement of sciences...

  5. Chromium Isotope Behaviour During Aerobic Microbial Reduction Activities

    Science.gov (United States)

    Zhang, Q.; Amor, K.; Porcelli, D.; Thompson, I.

    2014-12-01

    Microbial activity is a very important, and possibly even the dominant, reduction mechanism for many metals in natural water systems. Isotope fractionations during microbial metal reduction can reflect one major mechanism in metal cycling in the environment, and isotopic signatures can be used to identify and quantify reduction processes during biogeochemical cycling in the present environment as well as in the past. There are many Cr (VI)-reducing bacteria that have been discovered and isolated from the environment, and Cr isotopes were found to be fractionated during microbial reduction processes. In this study, Cr reduction experiments have been undertaken to determine the conditions under which Cr is reduced and the corresponding isotope signals that are generated. The experiments have been done with a facultative bacteria Pseudomonas fluorescens LB 300, and several parameters that have potential impact on reduction mechanisms have been investigated. Electron donors are important for bacteria growth and metabolism. One factor that can control the rate of Cr reduction is the nature of the electron donor. The results show that using citrate as an electron donor can stimulate bacteria reduction activity to a large extent; the reduction rate is much higher (15.10 mgˑL-1hour-1) compared with experiments using glucose (6.65 mgˑL-1ˑhour-1), acetate (4.88 mgˑL-1hour-1) or propionate (4.85 mgˑL-1hour-1) as electron donors. Groups with higher electron donor concentrations have higher reduction rates. Chromium is toxic, and when increasing Cr concentrations in the medium, the bacteria reduction rate is also higher, which reflects bacteria adapting to the toxic environment. In the natural environment, under different pH conditions, bacteria may metabolise in different ways. In our experiments with pH, bacteria performed better in reducing Cr (VI) when pH = 8, and there are no significant differences between groups with pH = 4 or pH = 6. To investigate this further, Cr

  6. Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

    Science.gov (United States)

    Annewandter, Robert

    2014-05-01

    The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced gas transport and subsequent soil gas sampling during On-Site inspections. Generally, gas transport has been widely studied with different numerical codes. However, gas transport of radioxenons and radioiodines in the post-detonation regime and their possible fractionation is still neglected in the open peer-reviewed literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the multiple isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radionuclides, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different mass diffusivities due to mass differences between the radionuclides. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures or highly conductive faults which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a so-called ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which is recognized by the oil industry as leading in Discrete Fracture-Matrix (DFM) simulations. It has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations, fracture propagation in fractured, porous media, and Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic differential equations by a complementary finite

  7. Non-destructive measurement of carbonic anhydrase activity and the oxygen isotope composition of soil water

    Science.gov (United States)

    Jones, Sam; Sauze, Joana; Ogée, Jérôme; Wohl, Steven; Bosc, Alexandre; Wingate, Lisa

    2016-04-01

    Carbonic anhydrases are a group of metalloenzymes that catalyse the hydration of aqueous carbon dioxide (CO2). The expression of carbonic anhydrase by bacteria, archaea and eukarya has been linked to a variety of important biological processes including pH regulation, substrate supply and biomineralisation. As oxygen isotopes are exchanged between CO2 and water during hydration, the presence of carbonic anhydrase in plants and soil organisms also influences the oxygen isotope budget of atmospheric CO2. Leaf and soil water pools have distinct oxygen isotope compositions, owing to differences in pool sizes and evaporation rates, which are imparted on CO2during hydration. These differences in the isotopic signature of CO2 interacting with leaves and soil can be used to partition the contribution of photosynthesis and soil respiration to net terrestrial CO2 exchange. However, this relies on our knowledge of soil carbonic anhydrase activity and currently, the prevalence and function of these enzymes in soils is poorly understood. Isotopic approaches used to estimate soil carbonic anhydrase activity typically involve the inversion of models describing the oxygen isotope composition of CO2 fluxes to solve for the apparent, potentially catalysed, rate of oxygen exchange during hydration. This requires information about the composition of CO2 in isotopic equilibrium with soil water obtained from destructive, depth-resolved soil water sampling. This can represent a significant challenge in data collection given the considerable potential for spatial and temporal variability in the isotopic composition of soil water and limited a priori information with respect to the appropriate sampling resolution and depth. We investigated whether we could circumvent this requirement by constraining carbonic anhydrase activity and the composition of soil water in isotopic equilibrium with CO2 by solving simultaneously the mass balance for two soil CO2 steady states differing only in the

  8. Reconstruction of the isotope activity content of heterogeneous nuclear waste drums.

    Science.gov (United States)

    Krings, Thomas; Mauerhofer, Eric

    2012-07-01

    Radioactive waste must be characterized in order to verify its conformance with national regulations for intermediate storage or its disposal. Segmented gamma scanning (SGS) is a most widely applied non-destructive analytical technique for the characterization of radioactive waste drums. The isotope specific activity content is generally calculated assuming a homogeneous matrix and activity distribution for each measured drum segment. However, real radioactive waste drums exhibit non-uniform isotope and density distributions most affecting the reliability and accuracy of activities reconstruction in SGS. The presence of internal shielding structures in the waste drum contributes generally to a strong underestimation of the activity and this in particular for radioactive sources emitting low energy gamma-rays independently of their spatial distribution. In this work we present an improved method to quantify the activity of spatially concentrated gamma-emitting isotopes (point sources or hot spots) in heterogeneous waste drums with internal shielding structures. The isotope activity is reconstructed by numerical simulations and fits of the angular dependent count rate distribution recorded during the drum rotation in SGS using an analytical expression derived from a geometric model. First results of the improved method and enhancements of this method are shown and are compared to each other as well as to the conventional method which assumes a homogeneous matrix and activity distribution. It is shown that the new model improves the accuracy and the reliability of the activity reconstruction in SGS and that the presented algorithm is suitable with respect to the framework requirement of industrial application.

  9. C isotope fractionation during heterotrophic activity driven carbonate precipitation

    Science.gov (United States)

    Balci, Nurgul; Demirel, Cansu

    2016-04-01

    Stable carbon isotopic fractionation during carbonate precipitation induced by environmentally enriched heterotrophic halophilic microorganims was experimentally investigated under various salinity (% 4.5, %8, %15) conditions at 30 °C. Halophilic heterotrophic microorganims were enriched from a hypersaline Lake Acigöl located in SW Turkey (Balci et al.,2015) and later used for the precipitation experiments (solid and liquid medium). The carbonate precipitates had relatively high δ13C values (-4.3 to -16.9 ‰) compared to the δ13C values of the organic compounds that ranged from -27.5 to -25.4 ‰. At salinity of 4.5 % δ13C values of carbonate ranged from -4.9 ‰ to -10.9 ‰ with a 13C-enrichment factor of +20 to +16 ‰ higher than the δ13C values of the associated DOC (-27.5) . At salinity 8 % δ13C values of carbonate ranged from -16.3 ‰ to -11.7 ‰ with a 13C-enrichment factor of+11.3 to+15.9 ‰ higher than the δ13C values of the associated DOC. The respected values for 15 % salinity ranged from -12.3 ‰ to -9.7 ‰ with a 13C-enrichment factor of +15.2 to+16.8 ‰ higher than the δ13C values of the associated DOC. The carbonate precipitates produced in the solid medium are more enriched in 13C relative to liquid culture experiments. These results suggest that the carbon in the solid was derived from both the bacterial oxidation of organic compounds in the medium and from the atmospheric CO2. A solid medium used in the experiments may have suppressed convective and advective mass transport favouring diffusion-controlled system. This determination suggests that the rate and equilibration of CO2 exchange with the atmosphere is the major control on C isotope composition of carbonate minerals precipitated in the experiments. Key words: Lake Acıgöl, halophilic bacteria, carbonate biomineralization, C isotopes References Nurgul Balci, Meryem Menekşe, Nevin Gül Karagüler, M. Şeref Sönmez,Patrick Meister 2015.Reproducing authigenic carbonate

  10. Carbon isotope fractionation of chlorinated ethenes during oxidation by Fe{sup 2+} activated persulfate

    Energy Technology Data Exchange (ETDEWEB)

    Marchesi, Massimo, E-mail: m2marche@uwaterloo.ca [Departament de Cristallografia, Mineralogia i Diposits Minerals, Universitat de Barcelona, Barcelona, Catalunya 08028 (Spain); Earth and Environmental Department, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Aravena, Ramon [Earth and Environmental Department, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Sra, Kanwartej S. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Golder Associates Inc, Toronto, Ontario, Canada L5N 5Z7 (Canada); Thomson, Neil R. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Otero, Neus; Soler, Albert [Departament de Cristallografia, Mineralogia i Diposits Minerals, Universitat de Barcelona, Barcelona, Catalunya 08028 (Spain); Mancini, Silvia [Golder Associates Inc, Toronto, Ontario, Canada L5N 5Z7 (Canada)

    2012-09-01

    The increased use of persulfate (S{sub 2}O{sub 8}{sup 2-}) for in situ chemical oxidation to treat groundwater and soils contaminated by chlorinated hydrocarbon compounds (CHCs) requires unbiased methods to assess treatment performance. Stable carbon isotope analysis offers a potential tool for assessing the in situ treatment performance of persulfate at sites contaminated with CHCs. This study investigated the extent of C isotope fractionation during oxidation of tetrachloroethene (PCE), trichloroethene (TCE) and cis-dichloroethene (cis-DCE) by persulfate activated by ferrous ion (Fe{sup 2+}). An average carbon isotope enrichment factor {epsilon}{sub bulk} of - 4.9 Per-Mille-Sign for PCE, - 3.6 Per-Mille-Sign for TCE and - 7.6 Per-Mille-Sign for cis-DCE were obtained in batch experiments. Variations in the initial S{sub 2}O{sub 8}{sup 2-}/Fe{sup 2+}/CHC molar ratios did not result in any significant differences in carbon isotope fractionation. The occurrence of carbon isotope fractionation during oxidation and the lack of dependence of enrichment factors upon the S{sub 2}O{sub 8}{sup 2-}/Fe{sup 2+}/CHC molar ratio demonstrate that carbon isotope analysis can potentially be used at contaminated sites as an additional technique to estimate treatment efficacy during oxidation of CHCs by Fe{sup 2+} activated persulfate. Highlights: Black-Right-Pointing-Pointer The performance of in situ chemical oxidation (ISCO) is still difficult to assess. Black-Right-Pointing-Pointer We investigated the potential of carbon isotope analysis as a new assessing tool. Black-Right-Pointing-Pointer C isotope of PCE, TCE and DCE oxidized by persulfate activated by Fe{sup 2+} was measured. Black-Right-Pointing-Pointer Enrichment factors of - 4.9 Per-Mille-Sign for PCE, - 3.6 Per-Mille-Sign for TCE and - 7.6 Per-Mille-Sign for cisDCE were obtained. Black-Right-Pointing-Pointer Carbon isotope can potentially be used to estimate the ISCO treatment efficacy.

  11. Calcium isotopic compositions as tracers of vegetation activity in boreal permafrost ecosystems (Kulingdakan watershed, Central Siberia)

    Science.gov (United States)

    Bagard, M.; Schmitt, A.; Chabaux, F. J.; Viers, J.; Pokrovsky, O. S.; Prokushkin, A. S.; Stille, P.; Dupré, B.

    2010-12-01

    In this work, we propose to investigate the geochemical potential of calcium isotopic fractionations in a forested boreal watershed to trace the impact of vegetation activity. This is the first study carried out in a geographical area characterized by deep and continuous permafrost. For this survey, we measured Ca and Sr isotopic compositions in the different compartments (stream waters, soil solutions, precipitations, rock, soils and soil leachates, vegetation) of a 4,100 ha Siberian watershed, the Kulingdakan watershed (Putorana Plateau, Central Siberia). Our results show that the activity of the vegetation is the only process that fractionates significantly calcium isotopes within the watershed. Indeed, Ca uptake by plants and its subsequent storage in larch tree organs favours 40Ca relatively to 44Ca. Vegetation decomposition releases light δ44/40Ca that affects calcium isotopic compositions of soil solution and soil exchangeable fractions. However, this biological impact is significant only for the South-facing slope of the watershed. Indeed, soil pools from the North-facing slope present no imprint of organic matter degradation in their δ44/40Ca signatures. Furthermore, the major difference between South- and North- facing slopes lies in the importance of the vegetation and its decomposition rate. Thus, we propose that in boreal permafrost areas with limited runoff, the available stock of biomass is critical to induce or not a significant vegetation impact on the calcium isotopic compositions in the soil-water system. As a consequence, the study of preserved calcium isotopic compositions in paleosoil exchangeable phases might bring relevant information on the evolution of biological activity at the watershed scale.

  12. Assessment of Non-Traditional Isotopic Ratios by Mass Spectrometry for Analysis of Nuclear Activities

    Science.gov (United States)

    2016-03-01

    Assessment of Non-traditional Isotopic Ratios by Mass Spectrometry for Analysis of Nuclear Activities Distribution Statement A. Approved for pubic...12. DISTRIBUTION / AVAILABILITY STATEMENT 13. SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF...Fahrenheit ( o F) [T( o F) + 459.67]/1.8 kelvin (K) Radiation curie (Ci) [ activity of radionuclides] 3.7 × 10 10 per second (s –1 ) [becquerel (Bq

  13. A non-isotopic assay for histone deacetylase activity.

    Science.gov (United States)

    Hoffmann, K; Brosch, G; Loidl, P; Jung, M

    1999-05-01

    Inhibitors of histone deacetylase (HD) bear great potential as new drugs due to their ability to modulate transcription and to induce apoptosis or differentiation in cancer cells. To study the activity of HD and the effect of potential inhibitors in vitro so far only radio-active assays have existed. For the search of new inhibitors and for the use in HD identification and purification we established a simple, non-radioactive assay that allows screening of large numbers of compounds. The assay is based on an aminocoumarin derivative of an Omega-acetylated lysine as enzyme substrate.

  14. Isotope-Dilution Mass Spectrometry for Quantification of Urinary Active Androgens Separated by Gas Chromatography

    OpenAIRE

    Su Hyeon Lee; Man Ho Choi; Won-Yong Lee; Bong Chul Chung

    2010-01-01

    Cross reacting antibodies can cause an overestimation of the results of immunoassays. Therefore, alternative methodsare needed for the accurate quantification of steroids. Gas chromatography combined with isotope-dilution mass spectrometry(GC-IDMS) is developed to quantify urinary active androgens, testosterone, epitestosterone and dihydrotestosterone, which areclinically relevant androgens to both hair-loss and prostate diseases. The method devised involves enzymatic hydrolysis with β-glucur...

  15. Isotopic Evidence for Microbial Activity in Crystalline Bedrock Fractures - a Case Study from Olkiluoto, SW Finland

    Science.gov (United States)

    Sahlstedt, E. K.; Karhu, J.; Pitkänen, P.

    2015-12-01

    Changes in the geochemical environment in crystalline bedrock fractures were investigated using the stable isotopes of C, O and S in fracture filling minerals as tracers. Of special interest were the possible changes which may occur in the subsurface at low temperatures. Especially, the influence of microbial activity was recognized as a catalyst for inducing changes in the geochemical environment. The study site is the Olkiluoto island located on the western coast of Finland, planned to host a geological repository for nuclear waste. Fracture surfaces were investigated to recognize the latest mineralizations at the site. These fillings were comprised of thin plates or small euhedral crystals of calcite and pyrite. The carbon and sulfur isotope compositions of calcite and pyrite were measured from bulk material by conventional IRMS, and in situ by secondary ion mass spectrometry. A notable feature of the late-stage fillings was high variabilities in the δ13C values of calcite and the δ34S values of pyrite, which ranged from -53.8 ‰ to +31.6 ‰ and from -50.4 ‰ to +77.7 ‰, respectively. Based on the isotopic compositions of the fillings, several features in the past hydrogeochemical environment could be recognized. The isotopic composition of the fracture fillings indicate an environment which was stratified with respect to depth. Characteristic features include bacterial sulfate reduction (BSR) occurring at depths 50 m. It appears that methanic conditions were replaced by sulfate reduction at depths >50 m likely due to infiltration of SO42--rich brackish waters. Sulfate reducing bacteria used mainly surface derived organic carbon as electron donors. Some indication of minor methanotrophic activity was recognized in anomalously low δ13C values of calcite, down to -53.8 ‰, at the depth range of 34-54 m. This methanotrophic activity may have been related to bacteria using CH4 as an electron donor in BSR.

  16. Isotopic signature of selected lanthanides for nuclear activities profiling using cloud point extraction and ICP-MS/MS.

    Science.gov (United States)

    Labrecque, Charles; Lebed, Pablo J; Larivière, Dominic

    2016-05-01

    The presence of fission products, which include numerous isotopes of lanthanides, can impact the isotopic ratios of these elements in the environment. A cloud point extraction (CPE) method was used as a preconcentration/separation strategy prior to measurement of isotopic ratios of three lanthanides (Nd, Sm, and Eu) by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). To minimise polyatomic interference, the combination of interferents removal by CPE, reaction/collision cell conditions in He and NH3 mode and tandem quadrupole configuration was investigated and provided optimal results for the determination of isotopic ratio in environmental samples. Isotopic ratios were initially measured in San Joaquin soil (NIST-2709a), an area with little contamination of nuclear origin. Finally, samples collected from three sites with known nuclear activities (Fangataufa Lagoon in French Polynesia, Chernobyl and the Ottawa River near Chalk River Laboratory) were analysed and all exhibited altered isotopic ratios for (143/145)Nd, (147/149)Sm, and (151/153)Eu. These results demonstrate the potential of CPE and ICP-MS/MS for the detection of altered isotopic ratio in environmental samples collected in area subjected to nuclear anthropogenic contamination. The detection of variations in these isotopic ratios of fission products represents the first application of CPE in nuclear forensic investigations of environmental samples.

  17. Investigation of recoil collection method for production of high specific activity nuclear medicine isotopes.

    Science.gov (United States)

    Cheng, K Y; Kunze, J F; Ehrhardt, G J

    1999-09-01

    High specific activity radiopharmaceuticals cannot readily be produced by (n, gamma) reactions in nuclear reactors, because the great abundance of parent atoms remaining have the same chemical characteristics as the produced isotope. We have investigated the effectiveness of using recoil atom collection methods for separating the produced radioisotope. Gold-198, produced from isotopically pure (natural) gold-197, was chosen for these experiments, which were run in the high flux (approximately 10(14) n/cm2 s thermal flux) of the reflector of the University of Missouri Research Reactor. Seven separate experiments were run, with a 2 mm separation between the emitter and the collector. Collection efficiencies were only a few percent of the radioisotope atoms produced in the top atomic layer of the emitter, instead of the 30% range anticipated. Furthermore, the collected radioisotope, instead of being nearly pure, contained a large quantity of the parent. Unless the reason for the "contamination" of product with the parent can be reduced by several orders of magnitude, this "surface hot atom recoil" method appears to offer no practical application for nuclear medicine isotope production.

  18. Multisubstrate isotope labeling and metagenomic analysis of active soil bacterial communities.

    Science.gov (United States)

    Verastegui, Y; Cheng, J; Engel, K; Kolczynski, D; Mortimer, S; Lavigne, J; Montalibet, J; Romantsov, T; Hall, M; McConkey, B J; Rose, D R; Tomashek, J J; Scott, B R; Charles, T C; Neufeld, J D

    2014-07-15

    Soil microbial diversity represents the largest global reservoir of novel microorganisms and enzymes. In this study, we coupled functional metagenomics and DNA stable-isotope probing (DNA-SIP) using multiple plant-derived carbon substrates and diverse soils to characterize active soil bacterial communities and their glycoside hydrolase genes, which have value for industrial applications. We incubated samples from three disparate Canadian soils (tundra, temperate rainforest, and agricultural) with five native carbon ((12)C) or stable-isotope-labeled ((13)C) carbohydrates (glucose, cellobiose, xylose, arabinose, and cellulose). Indicator species analysis revealed high specificity and fidelity for many uncultured and unclassified bacterial taxa in the heavy DNA for all soils and substrates. Among characterized taxa, Actinomycetales (Salinibacterium), Rhizobiales (Devosia), Rhodospirillales (Telmatospirillum), and Caulobacterales (Phenylobacterium and Asticcacaulis) were bacterial indicator species for the heavy substrates and soils tested. Both Actinomycetales and Caulobacterales (Phenylobacterium) were associated with metabolism of cellulose, and Alphaproteobacteria were associated with the metabolism of arabinose; members of the order Rhizobiales were strongly associated with the metabolism of xylose. Annotated metagenomic data suggested diverse glycoside hydrolase gene representation within the pooled heavy DNA. By screening 2,876 cloned fragments derived from the (13)C-labeled DNA isolated from soils incubated with cellulose, we demonstrate the power of combining DNA-SIP, multiple-displacement amplification (MDA), and functional metagenomics by efficiently isolating multiple clones with activity on carboxymethyl cellulose and fluorogenic proxy substrates for carbohydrate-active enzymes. Importance: The ability to identify genes based on function, instead of sequence homology, allows the discovery of genes that would not be identified through sequence alone. This

  19. DNA-based stable isotope probing enables the identification of active bacterial endophytes in potatoes.

    Science.gov (United States)

    Rasche, Frank; Lueders, Tillmann; Schloter, Michael; Schaefer, Sabine; Buegger, Franz; Gattinger, Andreas; Hood-Nowotny, Rebecca C; Sessitsch, Angela

    2009-03-01

    A (13)CO2 (99 atom-%, 350 ppm) incubation experiment was performed to identify active bacterial endophytes in two cultivars of Solanum tuberosum, cultivars Desirée and Merkur. We showed that after the assimilation and photosynthetic transformation of (13)CO2 into (13)C-labeled metabolites by the plant, the most directly active, cultivar specific heterotrophic endophytic bacteria that consume these labeled metabolite scan be identified by DNA stable isotope probing (DNA-SIP).Density-resolved DNA fractions obtained from SIP were subjected to 16S rRNA gene-based community analysis using terminal restriction fragment length polymorphism analysis and sequencing of generated gene libraries.Community profiling revealed community compositions that were dominated by plant chloroplast and mitochondrial 16S rRNA genes for the 'light' fractions of (13)CO2-incubated potato cultivars and of potato cultivars not incubated with (13)CO2. In the 'heavy' fractions of the (13)CO2-incubated endophyte DNA, a bacterial 492-bp terminal restriction fragment became abundant, which could be clearly identified as Acinetobacter and Acidovorax spp. in cultivars Merkur and Desirée,respectively, indicating cultivar-dependent distinctions in (13)C-label flow. These two species represent two common potato endophytes with known plant-beneficial activities.The approach demonstrated the successful detection of active bacterial endophytes in potato. DNA-SIP therefore offers new opportunities for exploring the complex nature of plant-microbe interactions and plant-dependent microbial metabolisms within the endosphere.

  20. Strontium isotope geochemistry of groundwater affected by human activities in Nandong underground river system, China

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Yongjun, E-mail: jiangjyj@swu.edu.cn [School of Geographical Sciences, Southwest University, Chongqing 400715 (China)] [Institute of Karst Environment and Rock Desertification Rehabilitation, Chongqing 400715 (China)

    2011-03-15

    Research highlights: {yields} Spatio-temporal variations of Sr concentrations and Sr isotopic composition of groundwater were investigated in a karst underground river system. {yields} Agricultural fertilizers and sewage effluents significantly modified the natural Sr isotopic signature of karst groundwater. {yields} Sr in the carbonate aquifers was relatively non-radiogenic, with low Sr concentrations, while anthropogenic Sr correlated with agricultural fertilizers and sewage effluents was relatively radiogenic, with higher Sr concentrations. {yields} {sup 87}Sr/{sup 86}Sr ratios can provide key information for natural and anthropogenic sources in karst groundwater. - Abstract: The Nandong Underground River System (NURS) is located in a typical karst area dominated by agriculture in SE Yunnan Province, China. Groundwater plays an important role in the social and economical development in the area. The effects of human activities (agriculture and sewage effluents) on the Sr isotope geochemistry were investigated in the NURS. Seventy-two representative groundwater samples, which were collected from different aquifers (calcite and dolomite), under varying land-use types, both in summer and winter, showed significant spatial differences and slight seasonal variations in Sr concentrations and {sup 87}Sr/{sup 86}Sr ratios. Agricultural fertilizers and sewage effluents significantly modified the natural {sup 87}Sr/{sup 86}Sr ratios signature of groundwater that was otherwise dominated by water-rock interaction. Three major sources of Sr could be distinguished by {sup 87}Sr/{sup 86}Sr ratios and Sr concentrations in karst groundwater. Two sources of Sr are the Triassic calcite and dolomite aquifers, where waters have low Sr concentrations (0.1-0.2 mg/L) and low {sup 87}Sr/{sup 86}Sr ratios (0.7075-0.7080 and 0.7080-0.7100, respectively); the third source is anthropogenic Sr from agricultural fertilizers and sewage effluents with waters affected having radiogenic {sup 87

  1. Activation cross-section measurement of a sort of nuclide produced with a target including two isotopes

    Institute of Scientific and Technical Information of China (English)

    ZHOU Feng-Qun; TIAN Ming-Li; SONG Yue-Li; LAN Chang-Lin; KONG Xiang-Zhong

    2013-01-01

    Based on a formula used to calculate the activation cross-section sum of two reactions producing a sort of nuclide with a target including two isotopes,the related problems in some references have been analyzed and discussed.It is pointed out that the calculation methods of the cross-section sum of two reactions producing the same radioactive nuclide for two isotopes in some references are improper and usually it is impossible to obtain the correct cross-section sum of two reactions producing the same radioactive nuclide for two isotopes in the case of using natural samples.At the same time,the related concepts are clarified and the correct processing method and representation are given.The comparison with the experimental results show that the theoretical analysis results are right.

  2. Chlorine isotopes of thermal springs in arc volcanoes for tracing shallow magmatic activity

    Science.gov (United States)

    Li, Long; Bonifacie, Magali; Aubaud, Cyril; Crispi, Olivier; Dessert, Céline; Agrinier, Pierre

    2015-03-01

    The evaluation of the status of shallow magma body (i.e., from the final intrusion stage, to quiescence, and back to activity), one of the key parameters that trigger and sustain volcanic eruptions, has been challenging in modern volcanology. Among volatile tracers, chlorine (Cl) uniquely exsolves at shallow depths and is highly hydrophilic. Consequently, Cl enrichment in volcanic gases and thermal springs has been proposed as a sign for shallow magmatic activities. However, such enrichment could also result from numerous other processes (e.g., water evaporation, dissolution of old chloride mineral deposits, seawater contamination) that are unrelated to magmatic activity. Here, based on stable isotope compositions of chloride and dissolved inorganic carbon, as well as previous published 3He/4He data obtained in thermal springs from two recently erupted volcanoes (La Soufrière in Guadeloupe and Montagne Pelée in Martinique) in the Lesser Antilles Arc, we show that the magmatic Cl efficiently trapped in thermal springs displays negative δ37Cl values (≤ - 0.65 ‰), consistent with a slab-derived origin but distinct from the isotope compositions of chloride in surface reservoirs (e.g. seawater, local meteoric waters, rivers and cold springs) displaying common δ37Cl values of around 0‰. Using this δ37Cl difference as an index of magmatic Cl, we further examined thermal spring samples including a 30-year archive from two thermal springs in Guadeloupe covering samples from its last eruption in 1976-1977 to 2008 and an island-wide sampling event in Martinique in 2008 to trace the evolution of magmatic Cl in the volcanic hydrothermal systems over time. The results show that magmatic Cl can be rapidly flushed out of the hydrothermal systems within <30 to 80 years after the eruption, much quicker than other volatile tracers such as CO2 and noble gases, which can exsolve at greater depths and constantly migrate to the surface. Because arc volcanoes often have well

  3. Isotope microscopy visualization of the adsorption profile of 2-methylisoborneol and geosmin in powdered activated carbon.

    Science.gov (United States)

    Matsui, Yoshihiko; Sakamoto, Asuka; Nakao, Soichi; Taniguchi, Takuma; Matsushita, Taku; Shirasaki, Nobutaka; Sakamoto, Naoya; Yurimoto, Hisayoshi

    2014-09-16

    Decreasing the particle size of powdered activated carbon may enhance its equilibrium adsorption capacity for small molecules and micropollutants, such as 2-methylisoborneol (MIB) and geosmin, as well as for macromolecules and natural organic matter. Shell adsorption, in which adsorbates do not completely penetrate the adsorbent but instead preferentially adsorb near the outer surface of the adsorbent, may explain this enhancement in equilibrium adsorption capacity. Here, we used isotope microscopy and deuterium-doped MIB and geosmin to directly visualize the solid-phase adsorbate concentration profiles of MIB and geosmin in carbon particles. The deuterium/hydrogen ratio, which we used as an index of the solid-phase concentration of MIB and geosmin, was higher in the shell region than in the inner region of carbon particles. Solid-phase concentrations of MIB and geosmin obtained from the deuterium/hydrogen ratio roughly agreed with those predicted by shell adsorption model analyses of isotherm data. The direct visualization of the localization of micropollutant adsorbates in activated carbon particles provided direct evidence of shell adsorption.

  4. Light Stable Isotopes in Aquifers Affected by Mining Activities in a Brazilian Mining Province

    Science.gov (United States)

    Moreira, R. M.; de Carvalho, J. B.

    2013-05-01

    Iron ore is presently a main item in the Brazilian commercial agenda. Large reserves have converted this utility into an important source of export earnings and, secondarily, of raw materials for the domestic industry. Parallel to a boom in mining activities in the last years environmental impacts and a stress on natural resources have soared. A region exhibiting pronouncedly intensive mining activities lies in the central part of the State of Minas Gerais, the third economy of the federation. Mines are sited right beside the capital and neighbor towns amounting to nearly five million inhabitants and a pronounced dependence on groundwater resources. Besides, this region is a water divide enclosing the sources of main contributors to the most strategic fluvial basins in the country. Iron ore is by large the main mineral but other metals (including gold and uranium), as well as non-metals such as limestone, quartz and granite, also occur. Given the significance of this commodity in the country's trade balance and the demand of water resources with acceptable quality for human consumption, the scale of ensuing water use conflicts caused by its exploration is wide ranging and has to be coped with well grounded environmental assessment approaches. Tracer hydrology techniques might be a valuable tool in this context. The characteristics of the area being impacted have been surveyed, including climate and pluviometry, stratigraphic litology, geological structure, use of soil, mineral resources and their exploration, surface and ground water hydrology and their sundry uses. Data to be processed have been procured at local public agencies but as regard local hydrological features, particularly isotopic compositions, ad hoc surveys and methodologies were required. One instance concerns pluviometric isotopy due to the alpine character of the surveyed region altitude and temperature effects might take place. Hence different sites were monitored; cumulative pluviometer samples

  5. Specific activity and isotope abundances of strontium in purified strontium-82

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimmons, J. M.; Medvedev, D. G.; Mausner, L. F.

    2015-11-12

    A linear accelerator was used to irradiate a rubidium chloride target with protons to produce strontium-82 (Sr-82), and the Sr-82 was purified by ion exchange chromatography. The amount of strontium associated with the purified Sr-82 was determined by either: ICP-OES or method B which consisted of a summation of strontium quantified by gamma spectroscopy and ICP-MS. The summation method agreed within 10% to the ICP-OES for the total mass of strontium and the subsequent specific activities were determined to be 0.25–0.52 TBq mg-1. Method B was used to determine the isotope abundances by weight% of the purified Sr-82, and the abundances were: Sr-82 (10–20.7%), Sr-83 (0–0.05%), Sr-84 (35–48.5%), Sr-85 (16–25%), Sr-86 (12.5–23%), Sr-87 (0%), and Sr-88 (0–10%). The purified strontium contained mass amounts of Sr-82, Sr-84, Sr-85, Sr-86, and Sr-88 in abundances not associated with natural abundance, and 90% of the strontium was produced by the proton irradiation. A comparison of ICP-OES and method B for the analysis of Sr-82 indicated analysis by ICP-OES would be easier to determine total mass of strontium and comply with regulatory requirements. An ICP-OES analytical method for Sr-82 analysis was established and validated according to regulatory guidelines.

  6. An Evaluation of Activated Bismuth Isotopes in Environmental Samples From the Former Western Pacific Proving Grounds

    Energy Technology Data Exchange (ETDEWEB)

    Robison, W.L.; Brunk, J.A.; Jokela, T.A.

    2000-03-21

    {sup 207}Bi (t{sub 1/2}=32.2 y) was generated by activation of weapons material during a few ''clean'' nuclear tests at the U.S. Western Pacific Proving Grounds of Enewetak and Bikini Atolls. The radionuclides first appeared in the Enewetak environment during 1958 and in the environment of Bikini during 1956. Crater sediments from Bikini with high levels of {sup 207}Bi were analyzed by gamma spectrometry in an attempt to determine the relative concentrations of {sup 208}Bi (t{sup 1/2} = 3.68 x 10{sup 5} y). The bismuth isotopes were probably generated during the ''clean'', 9.3 Mt Poplar test held on 7/12/58. The atom ratio of {sup 208}Bi to {sup 207}Bi (R value) ranges from {approx}12 to over 200 in sections of core sediments from the largest nuclear crater at Bikini atoll. The presence of bismuth in the device is suggested to account for R values in excess of 10.

  7. Recent research activities and future subjects on stable- and radio-isotopes of chlorine in environment

    Energy Technology Data Exchange (ETDEWEB)

    Kushita, Kouhei [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-12-01

    This report reviews the recent studies on the stable- and radio-isotopes of chlorine from a viewpoint of environmental science, partly including historic references on this element. First, general properties, occurrence, and utilization of chlorine are described. Secondly, current status and research works on chlorine-compounds, which attract special attention in recent years as environmentally hazardous materials, are reported. Thirdly, research works on stable chlorine isotopes, {sup 35}Cl and {sup 37}Cl, are described with a focus laid on the newly-developed techniques; isotopic ratio mass spectrometry (IRMS) and thermal ionization mass spectrometry (TIMS). Fourthly, recent research works on chlorine radioisotopes, {sup 36}Cl etc., are described, focusing on the development of accelerator mass spectrometry (AMS) and its application to geochemistry and others. Finally, taking account of the above-mentioned recent works on Cl isotopes, possible future research subjects are discussed. (author)

  8. Concentrations and activity ratios of uranium isotopes in groundwater from Doñana National Park, South of Spain

    Science.gov (United States)

    Bolívar, J. P.; Olías, M.; González-García, F.; García-Tenorio, R.

    2008-08-01

    The levels and distribution of natural radionuclides in groundwaters from the unconfined Almonte-Marismas aquifer, upon which Doñana National Park is located, have been analysed. Most sampled points were multiple piezometers trying to study the vertical distribution of the hydrogeochemical characteristics in the aquifer. Temperature, pH, electrical conductivity, dissolved oxygen and redox potential were determined in the field. A large number of parameters, physico-chemical properties, major and minor ions, trace elements and natural radionuclides (U-isotopes, Th-isotopes, Ra-isotopes and 210Po), were also analysed. In the southern zone, where aeolian sands crop out, water composition is of the sodium chloride type, and the lower U-isotopes concentrations have been obtained. As water circulates through the aquifer, bicarbonate and calcium concentrations increase slightly, and higher radionuclides concentrations were measured. Finally, we have demonstrated that 234U/238U activity ratios can be used as markers of the type of groundwater and bedrock, as it has been the case for old waters with marine origin confined by a marsh in the south-east part of aquifer.

  9. Field-Scale Stable-Isotope Probing of Active Methanotrophs in a Landfill-Cover Soil

    Science.gov (United States)

    Schroth, M. H.; Henneberger, R.; Chiri, E.

    2012-12-01

    The greenhouse gas methane (CH4) is an important contributor to global climate change. While its atmospheric concentration is increasing, a large portion of produced CH4 never reaches the atmosphere, but is consumed by aerobic methane-oxidizing bacteria (MOB). The latter are ubiquitous in soils and utilize CH4 as sole source of energy and carbon. Among other methods, MOB may be differentiated based on characteristic phospholipid fatty acids (PLFA). Stable-isotope probing (SIP) on PLFA has been widely applied to identify active members of MOB communities in laboratory incubation studies, but results are often difficult to extrapolate to the field. Thus, novel field-scale approaches are needed to link activity and identity of MOB in their natural environment. We present results of field experiments in which we combined PLFA-SIP with gas push-pull tests (GPPTs) to label active MOB at the field-scale while simultaneously quantifying CH4 oxidation activity. During a SIP-GPPT, a mixture of reactive (here 13CH4, O2) and non-reactive tracer gases (e.g., Ar, Ne, He) is injected into the soil at a location of interest. Thereafter, gas flow is reversed and the gas mixture diluted with soil air is extracted from the same location and sampled periodically. Rate constants for CH4 oxidation can be calculated by analyzing breakthrough curves of 13CH4 and a suitable non-reactive tracer gas. SIP-GPPTs were performed in a landfill-cover soil, and feasibility of this novel approach was tested at several locations along a gradient of MOB activity and soil temperature. Soil samples were collected before and after SIP-GPPTs, total PLFA were extracted, and incorporation of 13C in the polar lipid fraction was analyzed. Potential CH4 oxidation rates derived from SIP-GPPTs were similar to those derived from regular GPPTs (using unlabeled CH4) performed at the same locations prior to SIP-GPPTs, indicating that application of 13CH4 did not adversely affect bacterial CH4 oxidation rates. Rates

  10. Generation of Radixenon Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    McIntyre, Justin I.; Bowyer, Ted W.; Hayes, James C.; Heimbigner, Tom R.; Morris, Scott J.; Panisko, Mark E.; Pitts, W. K.; Pratt, Sharon L.; Reeder, Paul L.; Thomas, Charles W.

    2003-06-30

    Pacific Northwest National Laboratory has developed an automated system for separating Xe from air and can detect the following radioxenon isotopes, 131mXe, 133mXe, 133Xe, and 135Xe. This report details the techniques used to generate the various radioxenon isotopes that are used for the calibration of the detector as well as other isotopes that have the potential to interfere with the fission produced radioxenon isotopes. Fission production is covered first using highly enriched uranium followed by a description and results from an experiment to produce radioxenon isotopes from neutron activation of ambient xenon.

  11. Activities of \\gamma-ray emitting isotopes in rainwater from Greater Sudbury, Canada following the Fukushima incident

    CERN Document Server

    Cleveland, B T; Lawson, I T; Smith, N J T; Vazquez-Jauregui, E

    2012-01-01

    We report the activity measured in rainwater samples collected in the Greater Sudbury area of eastern Canada on 3, 16, 20, and 26 April 2011. The samples were gamma-ray counted in a germanium detector and the isotopes 131I and 137Cs, produced by the fission of 235U, and 134Cs, produced by neutron capture on 133Cs, were observed at elevated levels compared to a reference sample of ice-water. These elevated activities are ascribed to the accident at the Fukushima Dai-ichi nuclear reactor complex in Japan that followed the 11 March earthquake and tsunami. The activity levels observed at no time presented health concerns.

  12. Activable enriched stable isotope iron-58 for monitoring absorption rate of juvenile athletes for iron: a case study.

    Science.gov (United States)

    Qian, Qinfang; Chai, Zhifang; Feng, Weiyu; Chen, Jidi; Zhang, Peiqun; Pan, Jianxiang

    2002-09-01

    Activable enriched stable isotopes can play a unique role in studies of nutritional status, metabolism, absorption rates, and bioavailability of minerals. As a practical example, eight juvenile athletes were selected to test the absorption rates of iron during training and non-training periods by enriched stable isotope of Fe-58 (enriched degree: 51.1%) via activation analysis Fe-58 (n, gamma) Fe-59 of the collected feces samples. The results indicated that the average iron absorption rates of the juvenile athletes with and without training are 9.1 +/- 2.8 and 11.9 +/- 4.7%, respectively, which implies that the long-term endurance training with high intensity makes the iron absorption rate of athletes lower. In the meantime, the comparison of the activable enriched isotope technique with atomic absorption spectrometry was performed, which showed that the former was better than the latter in reliability and sensitivity. It is because this nuclear method can distinguish the exogenous and endogenous iron in the samples, but not for non-nuclear methods.

  13. Measurement of radium isotope activities in reservoir and spring water in the Cameroon Central Region

    Directory of Open Access Journals (Sweden)

    Rose Lydie Marie

    2015-09-01

    Full Text Available Purpose: To determine the activities of 226Ra and 228Ra in the reservoir and spring water samples respectively during the dry and the rainy seasons; and to calculate the annual intake Ii (Bq/y for each type of water samples. Methods: Using both well calibrated Canberra NaI(Tl and HPGe detector systems, it was possible to determine the average specific activity of those radium’s isotopes in water samples which were collected in 2010, from Reservoirs and springs in Cameroon central region including Ngoaekelle, Minboman, Etoudi and Njoungolo. Results: The average specific activity values obtained for 226Ra and 228Ra in reservoir water samples were 8.76 ± 3.50 BqL-1 and 0.64 ± 0.28 BqL-1 during the dry season and, 8.24 ±3.48 BqL-1 and 0.58 ± 0.24 BqL-1 during the rainy season respectively. For spring water, the average values were 3.50 ± 0.63 BqL-1 and below 0.0002 BqL-1 (detection limit of 228Ra in water during the dry season; 3.20 ± 0.60 BqL-1 and below 0.0002 BqL-1 (detection limit of 228Ra in water during the rainy season respectively. Assuming that the volume of drinking water for adult is 2.5 litres per day, the average annual intakes of 226Ra and 228Ra through ingestion in these water samples were 7702 Bq/y and 575 Bq/y for reservoir water; 2993 Bq/y and < 0.25 for spring water respectively. Conclusion: The results have indicated that the annual intake by the population of sampling region as a result of 226Ra in these drinking waters is 7.7 × 103Bq/y more than the maximum limit fixed by ICRP which is 7 × 103 Bq/y. There is a need for regular monitoring the radiological water quality aspect in this region.

  14. The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and Aspergillus niger phytase

    Science.gov (United States)

    von Sperber, C.; Tamburini, F.; Brunner, B.; Bernasconi, S. M.; Frossard, E.

    2015-07-01

    Phosphorus (P) is an essential nutrient for living organisms. Under P-limiting conditions plants and microorganisms can exude extracellular phosphatases that release inorganic phosphate (Pi) from organic phosphorus compounds (Porg). Phytic acid (myo-inositol hexakisphosphate, IP6) is an important form of Porg in many soils. The enzymatic hydrolysis of IP6 by phytase yields available Pi and less phosphorylated inositol derivates as products. The hydrolysis of organic P compounds by phosphatases leaves an isotopic imprint on the oxygen isotope composition (δ18O) of released Pi, which might be used to trace P in the environment. This study aims at determining the effect of phytase on the oxygen isotope composition of released Pi. For this purpose, enzymatic assays with histidine acid phytases from wheat and Aspergillus niger were prepared using IP6, adenosine 5'-monophosphate (AMP) and glycerophosphate (GPO4) as substrates. For a comparison to the δ18O of Pi released by other extracellular enzymes, enzymatic assays with acid phosphatases from potato and wheat germ with IP6 as a substrate were prepared. During the hydrolysis of IP6 by phytase, four of the six Pi were released, and one oxygen atom from water was incorporated into each Pi. This incorporation of oxygen from water into Pi was subject to an apparent inverse isotopic fractionation (ϵ ~ 6 to 10 ‰), which was similar to that imparted by acid phosphatase from potato during the hydrolysis of IP6 (ϵ ~ 7 ‰), where less than three Pi were released. The incorporation of oxygen from water into Pi during the hydrolysis of AMP and GPO4 by phytase yielded a normal isotopic fractionation (ϵ ~ -12 ‰), similar to values reported for acid phosphatases from potato and wheat germ. We attribute this similarity in ϵ to the same amino acid sequence motif (RHGXRXP) at the active site of these enzymes, which leads to similar reaction mechanisms. We suggest that the striking

  15. The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and Aspergillus niger phytase

    Directory of Open Access Journals (Sweden)

    C. v. Sperber

    2015-03-01

    Full Text Available Phosphorus (P is an essential nutrient for living organisms. Under P-limiting conditions plants and microorganisms can exude extracellular phosphatases that release inorganic phosphate (Pi from organic phosphorus compounds (Porg. Phytic acid (IP6 is an important form of Porg in many soils. The enzymatic hydrolysis of IP6 by phytase yields plant available inorganic phosphate (Pi and less phosphorylated inositol derivates as products. The hydrolysis of organic P-compounds by phosphatases leaves an isotopic imprint on the oxygen isotope composition (δ18O of released Pi, which might be used to trace P in the environment. This study aims at determining the effect of phytase on the oxygen isotope composition of released Pi. For this purpose, enzymatic assays with histidine acid phytases from wheat and Aspergillus niger were prepared using IP6, adenosine 5'monophosphate (AMP and glycerophosphate (GPO4 as substrates. For a comparison to the δ18O of Pi released by other extracellular enzymes, enzymatic assays with acid phosphatases from potato and wheat germ with IP6 as substrate were prepared. During the hydrolysis of IP6 by phytase, four Pi are released, and one oxygen atom from water is incorporated into each Pi. This incorporation of oxygen from water into Pi is subject to an apparent inverse isotopic fractionation (ϵ ∼ 6 to 10‰, which is similar to that imparted by acid phosphatase from potato during the hydrolysis of IP6 (ϵ ∼ 7‰ where less than three Pi are released. The incorporation of oxygen from water into Pi during the hydrolysis of AMP and GPO4 by phytase yielded a normal isotopic fractionation (ϵ ∼ −12‰, again similar to values reported for acid phosphatases from potato and wheat germ. We attribute this similarity in ε to the same amino acid sequence motif (RHGXRXP at the active site of these enzymes, which leads to similar reaction mechanisms. We suggest that the striking substrate

  16. Preequilibrium and statistical model calculations for neutron activation cross sections on titanium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ivascu, M.; Avrigeanu, M.; Avrigeanu, V.

    1986-01-01

    Calculated data are presented on (n,p), (n,n'p) and (n,2n) reaction cross sections for stable titanium isotopes in the energy range from threshold up to 20 MeV. An improved preequilibrium approach, allowing a unitary use of preequilibrium and equilibrium emission parameters, has increased the agreement between calculated and experimental cross sections.

  17. Sr isotopes in the Orgueil CI meteorite: Chronology of early solar system hydrothermal activity

    Indian Academy of Sciences (India)

    J D Macdougall

    2000-03-01

    New Sr isotopic analyses and calculated formation ages of carbonates from the Orgueil CI meteorite are reported. Among the samples analyzed in this work, dolomites give the youngest formation ages and may have been deposited intermittently starting near the time of parent body formation and continuing for at least 30 Ma. The Sr isotope data also suggest that breunnerites (Fe-Mn-Mg carbonates) crystallized after dolomite formation. Leaching experiments on bulk meteorite samples provide evidence for a very mobile, water soluble Sr reservoir in Orgueil that is characterized by extremely radiogenic Sr (87Sr/86Sr ≈ 0.81- 0.82). This unsupported Sr reflects recent element redistribution, possibly at the time of parent body breakup recorded by the ∼10 Ma exposure age of Orgueil. The carbonate data in particular corroborate earlier indications that hydrothermal processes were among the earliest events to affect the CI parent body.

  18. Influence of orbital forcing and solar activity on water isotopes in precipitation during the mid- and late Holocene

    Directory of Open Access Journals (Sweden)

    S. Dietrich

    2013-01-01

    Full Text Available In this study we investigate the impact of mid- and late Holocene orbital forcing and solar activity on variations of the oxygen isotopic composition in precipitation. The investigation is motivated by a recently published speleothem δ18O record from the well-monitored Bunker Cave in Germany. The record reveals some high variability on multi-centennial to millennial scales that does not linearly correspond to orbital forcing. Our model study is based on a set of novel climate simulations performed with the atmosphere general circulation model ECHAM5-wiso enhanced by explicit water isotope diagnostics. From the performed model experiments, we derive the following major results: (1 the response of both orbital and solar forcing lead to changes in surface temperatures and δ18O in precipitation with similar magnitudes during the mid- and late Holocene. (2 Past δ18O anomalies correspond to changing temperatures in the orbital driven simulations. This does not hold true if an additional solar forcing is added. (3 Two orbital driven mid-Holocene experiments, simulating the mean climate state approximately 5000 and 6000 yr ago, yield very similar results. However, if an identical additional solar activity-induced forcing is added, the simulated changes of surface temperatures as well as δ18O between both periods differ. We conclude from our simulation results that non-linear effects and feedbacks of the orbital and solar activity forcing substantially alter the δ18O in precipitation pattern and its relation to temperature change.

  19. Tracing of ca 800 yr old mining activity in peat bog using Pb elemental concentrations and isotope compositions.

    Science.gov (United States)

    Baron, S.; Carignan, J.; Ploquin, A.

    2003-04-01

    Sixty sites of slags have been documented on the Mont-Lozère in southern France. The petrographic analysis shows that slags are metallurgical wastes (800 to 850 yr BP) which certainly result from smelting activity for lead and silver extraction (Ploquin et al., 2001). The aims of this study are: 1) to trace the source of Pb ores which supplied the smelting sites, by using the Pb isotopic composition of several surrounding Pb deposits, 2) to evaluate the actual pollution caused by these slags, by using elemental and isotopic compositions of soils, water and vegetation, and 3) to document the pollution history of the region, by using elemental and isotopic compositions of peat bog cores collected in the neighbourhood of the historical smelting sites. The lead isotopic composition of galena collected in most surrounding ores is very similar to that of different slag samples. On the other hand, the high precision of the results allowed us to select the mineralised areas which were probably the ore sources. The Pb isotopic composition of slags is even more homogeneous: 208/206 Pb: 2.092±0.002; 206/207 Pb: 1.179±0.001; 208/204 Pb: 38.663±0.025; 207/204 Pb: 15.665±0.006; 206/204 Pb: 18.476±0.023, and will allow source tracing in the environment. The "Narses Mortes" peat bog, around which two smelting sites have been reported, is strongly minerotrophic and contains 8 to 60% ash. A 1.40 m core have been retrieved and divided into 58 individual samples. Minerotrophic peat bog records both atmospheric deposition, soils leaching and the grounwater influence. The measured metal concentrations are normalised to Al contents of peat bog samples and the metal/Al ratios are compared to that of the Mont-Lozère granite: relative excess in metal concentrations are found in peat bog samples. An increasing excess of most metals (Pb, Zn, Cd...) was measured for surface samples, from 55 cm depth to the top of the core (23 cm depth). This profil might be attributed to atmospheric

  20. Variability in carbon isotope fractionation of trichloroethene during degradation by persulfate activated with zero-valent iron: Effects of inorganic anions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yunde [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Zhou, Aiguo, E-mail: aiguozhou@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Gan, Yiqun; Li, Xiaoqian [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)

    2016-04-01

    Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from − 3.4 ± 0.3 to − 4.3 ± 0.3 ‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from − 7.0 ± 0.4 to − 13.6 ± 1.2 ‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO{sub 4}·{sup −}). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO). - Highlights: • Significant C isotope fractionation for TCE degradation by Fe{sup 0} activated persulfate. • The enrichment factors was independent of Fe{sup 0}, SO{sub 4}{sup 2−}, or HCO{sub 3}{sup −} concentration. • Cl{sup −} significantly influenced the carbon isotope fractionation.

  1. Variability in carbon isotope fractionation of trichloroethene during degradation by persulfate activated with zero-valent iron: Effects of inorganic anions.

    Science.gov (United States)

    Liu, Yunde; Zhou, Aiguo; Gan, Yiqun; Li, Xiaoqian

    2016-04-01

    Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from -3.4±0.3 to -4.3±0.3‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from -7.0±0.4 to -13.6±1.2‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO4(-)). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO).

  2. Influence of orbital forcing and solar activity on water isotopes in precipitation during the mid and late Holocene

    Directory of Open Access Journals (Sweden)

    S. Dietrich

    2012-08-01

    Full Text Available In this study we investigate the impact of mid and late Holocene orbital forcing and solar activity on variations of the oxygen isotopic composition in precipitation. Our study is based on a set of novel climate simulations performed with the atmosphere general circulation model ECHAM5-wiso enhanced by explicit water isotope diagnostics. From the performed model experiments we derive the following major results: (1 the response of both orbital and solar forcing lead to changes in surface temperatures and δ18O in precipitation with similar magnitudes during the mid and late Holocene. (2 Past δ18O anomalies correspond to changing temperatures in the orbital driven simulations. This does not hold true if an additional solar forcing is added. (3 Two orbital driven mid Holocene experiments, simulating the mean climate state approximately 5000 and 6000 yr ago, yield very similar results. However, if an identical additional solar activity-induced forcing is added, the simulated changes of surface temperatures as well as δ18O between both periods differ. From our findings we conclude that the Holocene variability of δ18O in precipitation, as stored in many paleoclimate archives, is rather complex to understand since the combined effect of different external forcings on δ18O in precipitation is non-linear.

  3. A revisit to vityaz transform fault area, Central Indian Ridge: Isotopic evidence of probable hydrothermal activity.

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Banerjee, R.; Xiao, Y.K.

    into the liquid phase during water -rock interactions at high temperatures [1,2]. Boron is one of the major elements of seawater and is significantly involved in the marine biogeochemical cycles. The two stable isotopes of boron, 10B and 11B, with a relative... in the mid-oceanic ridge (MOR) area leads to rifting and crustal generation and creates severe deformities in the oceanic crust, giving rise to hydrothermalism. The basalt-seawater interaction at the ridge sites brings about further changes...

  4. Investigation of Isotopic and Geochemical Evidence for an Active Planktonic Biota in the Precambrian

    Science.gov (United States)

    Kump, Lee R.

    1997-01-01

    The funded research was motivated by the earlier study of Burdett et al. (1990), who collected carbon and oxygen isotopic data from Paleoproterozoic rocks of the Northwest Territories from deep-and shallow-water facies of the Rocknest Platform. Their results displayed a possible decrease in (delta)C-13 with depth when arranged by increasing distance from the paleoshore. The most C-13-depleted samples were seafloor cements and fans from the underlying siliciclastic Odjick Formation, and slope carbonates of the Rocknest platform.

  5. Lead isotopes in soils and groundwaters as tracers of the impact of human activities on the surface environment: The Domizio-Flegreo Littoral (Italy) case study

    Science.gov (United States)

    Grezzi, G.; Ayuso, R.A.; de Vivo, B.; Lima, A.; Albanese, S.

    2011-01-01

    The isotopic signature of geogenic and anthropogenic materials, in combination with concentration data for pollutants, can help trace the origin and the extent of contamination in the environment. This approach is particularly effective if naturally occurring and anthropogenically introduced metals have different isotopic ratios. Lead isotope analysis on soils from 7 profiles (1. m depth) and on groundwaters from 8 wells have been used to determine the impact of human activities on the surface environment of Domizio-Flegreo Littoral. Result obtained show that in sub-rural areas the isotopic composition of the samples collected along the soil profiles of Domizio-Flegreo Littoral is likely mostly controlled by the nature of the parent geologic material (natural) while in more urbanized areas (Giugliano) Pb isotopic composition in superficial soils is mostly influenced by anthropic sources such as motor vehicles. Lead isotopic ratios in groundwaters also show that the use of pesticides and, probably, the influence of aerosols and the presence of illegal waste disposal can influence water quality. ?? 2010 Elsevier B.V.

  6. Intracellular Cadmium Isotope Fractionation

    Science.gov (United States)

    Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

    2011-12-01

    Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

  7. Dietary back-calculation using stable isotopes: can activities of enzymes involved in amino acid metabolism be used to improve estimates of trophic shifts in fish?

    Science.gov (United States)

    Gaye-Siessegger, Julia; Focken, Ulfert; Abel, Hansjörg; Becker, Klaus

    2007-06-01

    The aim of this study was (1) to assess the effects of dietary protein content and feeding level on trophic shifts of C and N isotopes (Delta delta(13)C(tissue-diet) and Delta delta(15)N(tissue-diet)) and (2) to test whether the measurement of the activities of two enzymes involved in the metabolism of amino acids could improve the accuracy of estimation of the trophic shifts of C and N isotopes. For this, 36 Nile tilapia (Oreochromis niloticus) were kept under controlled conditions for 8 weeks and fed at three different levels (2, 4 and 8 g kg(-0.8) d(-1)) with three diets differing in their protein content only (20, 29 and 39 %). For each fish, food to fish body trophic shifts of C and N isotopes were measured as well as the hepatic activities of aspartate aminotransferase (ASAT) and glutamate dehydrogenase (GDH). The feeding level affected the activities of ASAT and GDH as well as the trophic shifts of C and N isotopes significantly but the dietary protein content had no significant effect except on the specific activity of ASAT. Fish fed at the lowest level had significantly higher trophic shifts of C and N isotopes than fish fed at higher levels. The trophic shifts were significantly lower in fish with a high protein utilisation. Values of the 'goodness-of-fit' for linear regressions between enzyme activities and trophic shifts were low. Thus, activities of ASAT and GDH are not suitable for predicting estimates of trophic shifts in situations where the amount of food consumed or the dietary protein content is not known. In further studies, activities of enzymes involved in the metabolism of amino acids combined with measurements of the activities of other enzymes should be used to try and improve the accuracy of estimates of trophic shifts.

  8. Pu isotopes and {sup 241}Am activities determination in the evaluation of radiochemical sequential analyzes methodology for evaporator concentrate samples using alpha spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Reis Junior, Aluisio S.; Temba, Eliane S.C.; Kastner, Geraldo F.; Monteiro, Roberto P.G., E-mail: reisas@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (SERTA/CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Servico do Reator e Tecnicas Analiticas

    2015-07-01

    Alpha spectrometry analyzes were used for activity determinations of Pu and Am isotopes in evaporator concentrate samples from nuclear power plants. In this work it was used tracers for isotopes determination and quantification. The radiometric yields ranged from 60% to 100% and the Lower Limit of Detection was estimated as being 2.05 mBqKg{sup -1}. The relative standard deviations for replicate analysis were calculated for {sup 241}Am, 15.13% (sample J) and 9.38% (sample N), and for {sup 239+240}Pu, 8.16% (sample J) and 7.95% (sample N). (author)

  9. EROD activity and stable isotopes in seabirds to disentangle marine food web contamination after the Prestige oil spill

    Energy Technology Data Exchange (ETDEWEB)

    Velando, Alberto, E-mail: avelando@uvigo.e [Departamento de Ecoloxia e Bioloxia Animal, Facultade de Ciencias, Universidade de Vigo, Campus As Lagoas, 36310 Vigo (Spain); Munilla, Ignacio [Departamento de Botanica, Facultade de Farmacia, Universidade de Santiago de Compostela, Santiago de Compostela (Spain); Lopez-Alonso, Marta [Departamento de Patoloxia Animal, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo (Spain); Freire, Juan [Grupo de Recursos Marinos y Pesquerias Universidade da Coruna, A Coruna (Spain); Perez, Cristobal [Departamento de Ecoloxia e Bioloxia Animal, Facultade de Ciencias, Universidade de Vigo, Campus As Lagoas, 36310 Vigo (Spain)

    2010-05-15

    In this study, we measured via surgical sampling hepatic EROD activity in yellow-legged gulls from oiled and unoiled colonies, 17 months after the Prestige oil spill. We also analyzed stable isotope composition in feathers of the biopsied gulls, in an attempt to monitor oil incorporation into marine food web. We found that yellow-legged gulls in oiled colonies were being exposed to remnant oil as shown by hepatic EROD activity levels. EROD activity was related to feeding habits of individual gulls with apparent consequences on delayed lethality. Capture-recapture analysis of biopsied gulls suggests that the surgery technique did not affect gull survival, giving support to this technique as a monitoring tool for oil exposure assessment. Our study highlights the combination of different veterinary, toxicological and ecological methodologies as a useful approach for the monitoring of exposure to remnant oil after a large oil spill. - Two years after Prestige oil spill, seabirds were exposed to remnant oil related to their feeding habits with consequences on delayed lethality.

  10. An experimental investigation of multiple sulfur isotope fractionations during heterogenous reactions between SO2 and activated carbon

    Science.gov (United States)

    Hamasaki, H.; Watanabe, Y.; Ohmoto, H.

    2010-12-01

    Watanabe et al. (2009) reported that the reduced-S species produced from reactions between solid organic compounds and aqueous sulfate at 150-200 °C possessed anomalous isotopic fractionation (AIF) of S: Δ33S = 0.1 to 2.1 ‰. Based partly on these data, they suggested that the AIF-S signatures in some sedimentary rocks were produced during thermochemical sulfate reduction by solid organic compounds during the early stage of sediment diagenesis, rather than by atmospheric UV photolysis of volcanic SO2. Theoretical study by Lasaga et al. (2008) also suggested that variable AIF-S signatures could be generated during chemisorption of aqueous (or gaseous) S species on a solid surface (e.g., kerogen) under certain conditions. The main objective of this study was, therefore, to evaluate S isotope effects during different stages of reactions (e.g., adsorption, redox reactions) between a solid organic compound and SO2. We have conducted several series of experiments in a closed pyrex-glass system. About 1.8 gm (0.15 moles) of activated C (0.25-1.0 mm in diameter) was first evacuated at 300 °C for 5 days. Then 2.5 mmoles of pure SO2 gas was introduced in the system to react with activated carbon at 200 or 250 °C. Once the pSO2 became stabilized (typically after ~1 day), an aliquot of the SO2 gas (0.1 to 1.5 mmoles) was withdrawn into a pyrex-glass tube containing 20 % H2O2 solution to collect the SO2 as sulfate. After the pSO2 reached to a new steady value, another aliquot of SO2 was withdrawn from the system; sampling was continued until the amount of SO2 gas in the system decreased to 5 % of the initial value. The collected sulfate was converted to Ag2S for isotope analysis. After a series of experiment at 200 °C and another at 250 °C, the activated carbon was removed from the reaction system, treated sequentially by different chemical solutions to extract different forms of S compounds; the extracted S compounds were analyzed for their contents and isotopic ratios

  11. Quantification of Influenza Neuraminidase Activity by Ultra-High Performance Liquid Chromatography and Isotope Dilution Mass Spectrometry.

    Science.gov (United States)

    Solano, Maria I; Woolfitt, Adrian R; Williams, Tracie L; Pierce, Carrie L; Gubareva, Larisa V; Mishin, Vasiliy; Barr, John R

    2017-03-07

    Mounting evidence suggests that neuraminidase's functionality extends beyond its classical role in influenza virus infection and that antineuraminidase antibodies offer protective immunity. Therefore, a renewed interest in the development of neuraminidase (NA)-specific methods to characterize the glycoprotein and evaluate potential advantages for NA standardization in influenza vaccines has emerged. NA displays sialidase activity by cleaving off the terminal N-acetylneuraminic acid on α-2,3 or α-2,6 sialic acid containing receptors of host cells. The type and distribution of these sialic acid containing receptors is considered to be an important factor in transmission efficiency of influenza viruses between and among host species. Changes in hemagglutinin (HA) binding and NA specificity in reassortant viruses may be related to the emergence of new and potentially dangerous strains of influenza. Current methods to investigate neuraminidase activity use small derivatized sugars that are poor models for natural glycoprotein receptors and do not provide information on the linkage specificity. Here, a novel approach for rapid and accurate quantification of influenza neuraminidase activity is achieved utilizing ultra-high performance liquid chromatography (UPLC) and isotope dilution mass spectrometry (IDMS). Direct LC-MS/MS quantification of NA-released sialic acid provides precise measurement of influenza neuraminidase activity over a range of substrates. The method provides exceptional sensitivity and specificity with a limit of detection of 0.38 μM for sialic acid and the capacity to obtain accurate measurements of specific enzyme activity preference toward α-2,3-sialyllactose linkages, α-2,6-sialyllactose linkages, or whole glycosylated proteins such as fetuin.

  12. Low-Enriched Uranium Fuel Conversion Activities for the High Flux Isotope Reactor, Annual Report for FY 2011

    Energy Technology Data Exchange (ETDEWEB)

    Renfro, David G [ORNL; Cook, David Howard [ORNL; Freels, James D [ORNL; Griffin, Frederick P [ORNL; Ilas, Germina [ORNL; Sease, John D [ORNL; Chandler, David [ORNL

    2012-03-01

    This report describes progress made during FY11 in ORNL activities to support converting the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum (UMo) alloy. With both radial and axial contouring of the fuel foil and an increase in reactor power to 100 MW, calculations indicate that the HFIR can be operated with LEU fuel with no degradation in performance to users from the current levels achieved with HEU fuel. Studies are continuing to demonstrate that the fuel thermal safety margins can be preserved following conversion. Studies are also continuing to update other aspects of the reactor steady state operation and accident response for the effects of fuel conversion. Technical input has been provided to Oregon State University in support of their hydraulic testing program. The HFIR conversion schedule was revised and provided to the GTRI program. In addition to HFIR conversion activities, technical support was provided directly to the Fuel Fabrication Capability program manager.

  13. Nitrogen isotopic patterns of vegetation as affected by breeding activity of Black-tailed Gull (Larus crassiostris): A coupled analysis of feces, inorganic soil nitrogen and flora

    Energy Technology Data Exchange (ETDEWEB)

    Mizota, C., E-mail: mizota@iwate-u.ac.jp [Iwate University, Ueda 3-18-8, Morioka, Iwate 020-8550 (Japan)

    2009-11-15

    Two currently breeding colonies (Matsushima Bay and Rishiri island; northern Japan) of predominant Black-tailed Gull (Larus crassiostris) were studied for N isotopic patterns of flora, which is affected by increased supply of inorganic soil N derived from the microbial transformation of feces. Coupled samples of feces, topsoil and flora were collected in early to mid July (2008), when input of fecal N onto soils was at its maximum. As bird migration and breeding continued, native Japanese red-pine (Pinus densiflora), junipers (Juniperus chinensis and Juniperus rigita; Matsushima Bay colony) and Sasa senanensis (Rishiri colony) declined, while ornithocoprophilus exotic plants succeeded. Among tree species on the islands, P. densiflora with ectomycorrizal colonization appears highly susceptible to elevated concentrations of NH{sub 4}-N in the topsoil. A mechanism for best explaining the plant succession associated with the breeding activity of Black-tailed Gull was evidenced by two parameters: first, concomitant elevation of N content in the flora and second, inorganic soil N content, along with changes in N isotopic composition ({delta}{sup 15}N). Earlier isotopic data on the foliar N affected by breeding activity were compiled and reviewed. Emphasis was put on isotopic information for inorganic N in soils that controls plant succession.

  14. Impacts of Human Activities on the Occurrence of Groundwater Nitrate in an Alluvial Plain: A Multiple Isotopic Tracers Approach

    Institute of Scientific and Technical Information of China (English)

    Zhonghe Pang; Lijuan Yuan; Tianming Huang; Yanlong Kong; Jilai Liu; Yiman Li

    2013-01-01

    Nitrate pollution is a severe problem in areas with intensive agricultural activities.This study focuses on nitrate occurrence and its constraints in a selected alluvial fan using chemical data combined with environmental isotopic tracers (18O,3H,and 15N).Results show that groundwater nitrate in the study area is as high as 258.0 mg/L (hereafter NO3-) with an average of 86.8 mg/L against national drinking water limit of 45 mg/L and a regional baseline value of 14.4 mg/L.Outside of the riparian zone,nitrate occurrence is closely related to groundwater circulation and application of chemical fertilizer.High groundwater nitrate is found in the recharge area,where nitrate enters into groundwater through vertical infiltration,corresponding to high 3H and enriched 18O in the water.In the riparian zone,on the contrary,the fate of groundwater nitrate is strongly affected by groundwater level.Based on two sampling transects perpendicular to the riverbank,we found that the high level of nitrate corresponds to the deeper water table (25 m) near the urban center,where groundwater is heavily extracted.Groundwater nitrate is much lower (<12.4 mg/L) at localities with a shallow water table (5 m),which is likely caused by denitrification in the aquifer.

  15. Heterogeneous Isotopic Anomalies of Sm and Gd in the Norton County Meteorite: Evidence for Irradiation from the Active Early Sun

    Science.gov (United States)

    Hidaka, Hiroshi; Kondo, Tomoyo; Yoneda, Shigekazu

    2012-02-01

    Large and heterogeneous isotopic variations of 150Sm/149Sm and 158Gd/157Gd due to neutron capture reactions caused by cosmic-ray irradiation were found in chemical and mineral separates from the Norton County meteorite. The light-colored separates, consisting mainly of enstatite (Mg2Si2O6), have a very large neutron fluence of 1.98 × 1017 n cm-2, which is 10 times higher than that of the whole rock. Furthermore, four chemical separates showed a large variation in neutron fluences, ranging from 1.82 × 1016 to 1.87 × 1017 n cm-2. The variable amounts of neutron fluences from a small single fragment of the Norton County meteorite cannot be simply explained by single-stage cosmic-ray irradiation in space. Rare earth element (REE) analyses revealed that the fractions with high neutron fluences have similar chemical properties to those in the early condensates in the solar system, showing depletions of Eu and Yb in their REE abundance patterns. The data provide evidence for an activity of the early Sun (T Tauri), suggesting the migration of early and intense irradiation materials into the Norton County meteorite's parent body.

  16. Fractional Absorption of Active Absorbable Algal Calcium (AAACa and Calcium Carbonate Measured by a Dual Stable-Isotope Method

    Directory of Open Access Journals (Sweden)

    Steven A. Abrams

    2010-07-01

    Full Text Available With the use of stable isotopes, this study aimed to compare the bioavailability of active absorbable algal calcium (AAACa, obtained from oyster shell powder heated to a high temperature, with an additional heated seaweed component (Heated Algal Ingredient, HAI, with that of calcium carbonate. In 10 postmenopausal women volunteers aged 59 to 77 years (mean ± S.D., 67 ± 5.3, the fractional calcium absorption of AAACa and CaCO3 was measured by a dual stable isotope method. 44Ca-enriched CaCO3 and AAACa were administered in all subjects one month apart. After a fixed-menu breakfast and pre-test urine collection (Urine 0, 42Ca-enriched CaCl2 was intravenously injected, followed by oral administration of 44Ca-enriched CaCO3 without carrier 15 minutes later, and complete urine collection for the next 24 hours (Urine 24. The fractional calcium absorption was calculated as the ratio of Augmentation of 44Ca from Urine 0 to Urine 24/ augmentation of 42Ca from Urine 0 to Urine 24. Differences and changes of 44Ca and 42Ca were corrected by comparing each with 43Ca. Fractional absorption of AAACa (mean ± S.D., 23.1 ± 6.4, was distinctly and significantly higher than that of CaCO3 (14.7 ± 6.4; p = 0.0060 by paired t-test. The mean fractional absorption was approximately 1.57-times higher for AAACa than for CaCO3. The serum 25(OH vitamin D level was low (mean ± S.D., 14.2 ± 4.95 ng/ml, as is common in this age group in Japan. Among the parameters of the bone and mineral metabolism measured, none displayed a significant correlation with the fractional absorption of CaCO3 and AAACa. Higher fractional absorption of AAACa compared with CaCO3 supports previous reports on the more beneficial effect of AAACa than CaCO3 for osteoporosis.

  17. NEUTRON ACTIVATION ANALYSIS APPLICATIONS AT THE SAVANNAH RIVER SITE USING AN ISOTOPIC NEUTRON SOURCE

    Energy Technology Data Exchange (ETDEWEB)

    Diprete, D; C Diprete, C; Raymond Sigg, R

    2006-08-14

    NAA using {sup 252}Cf is used to address important areas of applied interest at SRS. Sensitivity needs for many of the applications are not severe; analyses are accomplished using a 21 mg {sup 252}Cf NAA facility. Because NAA allows analysis of bulk samples, it offers strong advantages for samples in difficult-to-digest matrices when its sensitivity is sufficient. Following radiochemical separation with stable carrier addition, chemical yields for a number methods are determined by neutron activation of the stable carrier. In some of the cases where no suitable stable carriers exist, the source has been used to generate radioactive tracers to yield separations.

  18. Carbon isotopic composition (δ(13)C and (14)C activity) of plant samples in the vicinity of the Slovene nuclear power plant.

    Science.gov (United States)

    Sturm, Martina; Vreča, Polona; Krajcar Bronić, Ines

    2012-08-01

    δ(13)C values of various plants (apples, wheat, and maize) collected in the vicinity of the Krško Nuclear Power Plant (Slovenia) during 2008 and 2009 were determined. By measuring dried samples and their carbonized counterparts we showed that no significant isotopic fractionation occurs during the carbonization phase of the sample preparation process in the laboratory. The measured δ(13)C values of the plants were used for δ(13)C correction of their measured (14)C activities.

  19. Enzymatic activities and stable isotope patterns of ectomycorrhizal fungi in relation to phylogeny and exploration types in an afrotropical rain forest.

    Science.gov (United States)

    Tedersoo, Leho; Naadel, Triin; Bahram, Mohammad; Pritsch, Karin; Buegger, Franz; Leal, Miguel; Kõljalg, Urmas; Põldmaa, Kadri

    2012-09-01

    Ectomycorrhizal (ECM) fungi obtain both mineral and simple organic nutrients from soil and transport these to plant roots. Natural abundance of stable isotopes (¹⁵N and ¹³C) in fruit bodies and potential enzymatic activities of ECM root tips provide insights into mineral nutrition of these mutualistic partners. By combining rDNA sequence analysis with enzymatic and stable isotope assays of root tips, we hypothesized that phylogenetic affinities of ECM fungi are more important than ECM exploration type, soil horizon and host plant in explaining the differences in mineral nutrition of trees in an African lowland rainforest. Ectomycorrhizal fungal species belonging to extraradical mycelium-rich morphotypes generally displayed the strongest potential activities of degradation enzymes, except for laccase. The signature of ¹⁵N was determined by the ECM fungal lineage, but not by the exploration type. Potential enzymatic activities of root tips were unrelated to ¹⁵N signature of ECM root tip. The lack of correlation suggests that these methods address different aspects in plant nutrient uptake. Stable isotope analysis of root tips could provide an additional indirect assessment of fungal and plant nutrition that enables enhancement of taxonomic coverage and control for soil depth and internal nitrogen cycling in fungal tissues.

  20. Therapeutic use of radioactive isotopes

    CERN Multimedia

    Caroline Duc

    2013-01-01

    In December, researchers from ISOLDE-CERN, the Paul Scherrer Institute (PSI) and the Institut Laue-Langevin (ILL) published the results of an in vivo study which successfully proved the effectiveness of four terbium isotopes for diagnosing and treating cancerous tumours.   Four terbium isotopes suitable for clinical purposes. “ISOLDE is the only installation capable of supplying terbium isotopes of such purity and intensity in the case of three out of the four types used in this study,” explains Karl Johnson, a physicist at ISOLDE.  “Producing over a thousand different isotopes, our equipment offers the widest choice of isotopes in the world!” Initially intended for fundamental physics research, ISOLDE has diversified its activities over time to invest in various projects in the materials science, biochemistry and nuclear medicine fields. The proof-of-concept study has confirmed that the four terbium isotopes 149Tb, 152Tb, 155Tb produ...

  1. Leatherback Isotopes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC is currently working on a project identifying global marine isotopes using leatherback turtles (Dermochelys coriacea) as the indicator species. We currently...

  2. Isotopic Paleoclimatology

    Science.gov (United States)

    Bowen, R.

    Paleotemperature scales were calculated by H. C. Urey and others in the 1950s to assess past temperatures, and later work using the stable isotopes of oxygen, hydrogen, and carbon employed standards such as Peedee belemnite (PDB) and Standard Mean Ocean Water (SMOW). Subsequently, subjects as diverse as ice volume and paleotemperatures, oceanic ice and sediment cores, Pleistocene/Holocene climatic changes, and isotope chronostratigraphy extending back to the Precambrian were investigated.

  3. Isotopic chirality

    Energy Technology Data Exchange (ETDEWEB)

    Floss, H.G. [Univ. of Washington, Seattle, WA (United States)

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  4. Sequential Assessment of Cell Cycle S Phase in Flow Cytometry: A Non-Isotopic Method to Measure Lymphocyte Activation In Vitro

    Directory of Open Access Journals (Sweden)

    Ch. Kohler

    1997-01-01

    Full Text Available Lymphocyte multiplication can be induced in vitro by mitogens or specific antigens, and is usually measured using isotopic methods involving tritiated thymidine. Cellular proliferation can also be analyzed by flow cytometry techniques based on cell cycle analysis through the measurement of DNA content. We applied this method to lymphocytes from 113 individuals, to evaluate lymphocyte proliferation after stimulation in vitro by a mitogen (phytohaemagglutinin, PHA or a recall antigen (tetanus toxoid, using a kinetic approach with four points sequential measurements of the S and G2 phases over six days of culture. The proportion of cells in S phase after PHA stimulation was significantly higher than in controls overall and as early as on day three of the culture. Activation with a recall antigen significantly induced increasing S phase cell proportions up to day six. These data suggest that flow cytometric assessment of the S phase could be a useful alternative to isotopic methods measuring lymphocyte reactivity in vitro.

  5. Capture of heavy hydrogen isotopes in a metal-organic framework with active Cu(I) sites

    Science.gov (United States)

    Weinrauch, I.; Savchenko, I.; Denysenko, D.; Souliou, S. M.; Kim, H.-H.; Le Tacon, M.; Daemen, L. L.; Cheng, Y.; Mavrandonakis, A.; Ramirez-Cuesta, A. J.; Volkmer, D.; Schütz, G.; Hirscher, M.; Heine, T.

    2017-03-01

    The production of pure deuterium and the removal of tritium from nuclear waste are the key challenges in separation of light isotopes. Presently, the technological methods are extremely energy- and cost-intensive. Here we report the capture of heavy hydrogen isotopes from hydrogen gas by selective adsorption at Cu(I) sites in a metal-organic framework. At the strongly binding Cu(I) sites (32 kJ mol-1) nuclear quantum effects result in higher adsorption enthalpies of heavier isotopes. The capture mechanism takes place most efficiently at temperatures above 80 K, when an isotope exchange allows the preferential adsorption of heavy isotopologues from the gas phase. Large difference in adsorption enthalpy of 2.5 kJ mol-1 between D2 and H2 results in D2-over-H2 selectivity of 11 at 100 K, to the best of our knowledge the largest value known to date. Combination of thermal desorption spectroscopy, Raman measurements, inelastic neutron scattering and first principles calculations for H2/D2 mixtures allows the prediction of selectivities for tritium-containing isotopologues.

  6. Radiosynthesis of [{sup 18}F]fluorophenyl-L-amino acids by isotopic exchange on carbonyl-activated precursors

    Energy Technology Data Exchange (ETDEWEB)

    Castillo Melean, Johnny

    2011-02-01

    Aromatic [{sup 18}F]fluoroamino acids have earlier been developed as promising probes for diagnostics using PET. However, a wider use of these radiofluorinated compounds has been limited due to radiosynthetic constraints. The work here presents an amenable three-step radiosynthesis pathway for the preparation of 2-[{sup 18}F]fluoro-L-phenylalanine (2-[{sup 18}F]Fphe), 2-[{sup 18}F]fluoro-L-tyrosine (2-[{sup 18}F]Ftyr), 6-[{sup 18}F]fuoro-L-m-tyrosine (6-[{sup 18}F]Fmtyr) and 6-[{sup 18}F]fluoro-L-DOPA (6-[{sup 18}F]FDOPA). For this, corresponding precursors were {sup 18}F-fluorinated by nucleophilic isotopic exchange, followed by either removal of an activating formyl group with Rh(PPh{sub 3}){sub 3}Cl or its conversion by Baeyer-Villiger oxidation, respectively, and subsequent hydrolysis of protecting groups in acidic medium. Two efficient synthetic approaches were developed for the preparation of highly functionalized fluoro-benzaldehydes and -ketones which were used as labeling precursors. The compounds (2S,5S)-tert-butyl 2-tert-butyl-5-(2-fluoro-5-formylbenzyl)-3-methyl-4-oxoimidazolidine-1 -carboxylate (1a), (2S,5S)-tert-butyl 5-(5-acetyl-2-fluorobenzyl)-2-tert-butyl-3-methyl-4-oxoimidazolidine-1 -carboxylate (1c), (2S,5S)-benzyl 2-tert-butyl-5-(2-fluoro-5-formylbenzyl)-3-methyl-4-oxoimidazolidine-1 -carbo-xylate (1d), 4-fluoro-3-(((2S,5R)-5-isopropyl-3,6-dimethoxy-2,5-dihydropyrazin-2-yl) me-thyl)b enzal-dehyde (1e) and 1-(4-fluoro-3-(((2S,5R)-5-isopropyl-3,6-dimethoxy-2,5-dihydropyrazin-2-yl) me-thy l)phenyl)ethanone (1f), could be prepared in six steps and overall yields of 41%, 48%, 37%, 27%, and 32%, respectively. (2S,5S)-tert-Butyl 5-(4-(benzyloxy)-2-fluoro-5-formylbenzyl)-2-tert-butyl-3-methyl-4 -oxoimidazolidi ne-1-carboxylate (1b) was prepared in ten steps with an overall yield of 19% while compounds (2S,5S)-tert-butyl 5-(5-(3,5-bis(trifluoromethyl)-benzoyl)-2-fluorobenzyl)-2-tert-butyl-3 -methyl-4-oxoimidazolidine-1-carboxylate (1g) and (2S,5S

  7. Higher peroxidase activity, leaf nutrient contents and carbon isotope composition changes in Arabidopsis thaliana are related to rutin stress.

    Science.gov (United States)

    Hussain, M Iftikhar; Reigosa, Manuel J

    2014-09-15

    Rutin, a plant secondary metabolite that is used in cosmetics and food additive and has known medicinal properties, protects plants from UV-B radiation and diseases. Rutin has been suggested to have potential in weed management, but its mode of action at physiological level is unknown. Here, we report the biochemical, physiological and oxidative response of Arabidopsis thaliana to rutin at micromolar concentrations. It was found that fresh weight; leaf mineral contents (nitrogen, sodium, potassium, copper and aluminum) were decreased following 1 week exposure to rutin. Arabidopsis roots generate significant amounts of reactive oxygen species after rutin treatment, consequently increasing membrane lipid peroxidation, decreasing leaf Ca(2+), Mg(2+), Zn(2+), Fe(2+) contents and losing root viability. Carbon isotope composition in A. thaliana leaves was less negative after rutin application than the control. Carbon isotope discrimination values were decreased following rutin treatment, with the highest reduction compared to the control at 750μM rutin. Rutin also inhibited the ratio of CO2 from leaf to air (ci/ca) at all concentrations. Total protein contents in A. thaliana leaves were decreased following rutin treatment. It was concluded carbon isotope discrimination coincided with protein degradation, increase lipid peroxidation and a decrease in ci/ca values may be the primary action site of rutin. The present results suggest that rutin possesses allelopathic potential and could be used as a candidate to develop environment friendly natural herbicide.

  8. RNA-Based Stable Isotope Probing Suggests Allobaculum spp. as Particularly Active Glucose Assimilators in a Complex Murine Microbiota Cultured In Vitro

    Science.gov (United States)

    Herrmann, Elena; Young, Wayne; Rosendale, Douglas; Reichert-Grimm, Verena; Conrad, Ralf

    2017-01-01

    RNA-based stable isotope probing (RNA-SIP) and metabolic profiling were used to detect actively glucose-consuming bacteria in a complex microbial community obtained from a murine model system. A faeces-derived microbiota was incubated under anaerobic conditions for 0, 2, and 4 h with 40 mM [U13C]glucose. Isopycnic density gradient ultracentrifugation and fractionation of isolated RNA into labeled and unlabeled fractions followed by 16S rRNA sequencing showed a quick adaptation of the bacterial community in response to the added sugar, which was dominated by unclassified Lachnospiraceae species. Inspection of distinct fractions of isotope-labeled RNA revealed Allobaculum spp. as particularly active glucose utilizers in the system, as the corresponding RNA showed significantly higher proportions among the labeled RNA. With time, the labeled sugar was used by a wider spectrum of faecal bacteria. Metabolic profiling indicated rapid fermentation of [U13C]glucose, with lactate, acetate, and propionate being the principal 13C-labeled fermentation products, and suggested that “cross-feeding” occurred in the system. RNA-SIP combined with metabolic profiling of 13C-labeled products allowed insights into the microbial assimilation of a general model substrate, demonstrating the appropriateness of this technology to study assimilation processes of nutritionally more relevant substrates, for example, prebiotic carbohydrates, in the gut microbiota of mice as a model system. PMID:28299315

  9. Identification of metabolically active methanogens in anaerobic digester by DNA Stable-Isotope Probing using 13C-acetate

    Directory of Open Access Journals (Sweden)

    V. Gowdaman

    2015-04-01

    Full Text Available Anaerobic digestion is gaining enormous attention due to the ability to covert organic wastes into biogas, an alternative sustainable energy. Methanogenic community plays a significant role in biogas production and also for proficient functioning of the anaerobic digester. Therefore, this study was carried out to investigate the methanogen diversity of a food waste anaerobic digester. After endogenous respiration, the digester samples were supplemented with isotopes of acetate to enrich methanogen population, and were analyzed using DNA-SIP (Stable-Isotope Probing. Following separation and fractionation of heavy (13C and light (12C DNA, PCR amplification was carried out using archaeal 16S rRNA gene followed by DGGE analysis. Sequencing of the prominent DGGE bands revealed the dominance of Methanocorpusculum labreanum species belonging to hydrogenotrophic Methanomicrobiales, which can produce methane in the presence of H2/CO2 and requires acetate for its growth. This is the first instance where Methanocorpusculum labreanum is being reported as a dominant species in an anaerobic digester operative on food waste.

  10. Formation of Kokumi-Enhancing γ-Glutamyl Dipeptides in Parmesan Cheese by Means of γ-Glutamyltransferase Activity and Stable Isotope Double-Labeling Studies.

    Science.gov (United States)

    Hillmann, Hedda; Behr, Jürgen; Ehrmann, Matthias A; Vogel, Rudi F; Hofmann, Thomas

    2016-03-01

    Recently, γ-glutamyl dipeptides (γ-GPs) were found to be responsible for the attractive kokumi flavor of Parmesan cheese (PC). Quantitation of γ-GPs and their parent amino acids in 13-, 24-, and 30-month ripened PC samples by LC-MS/MS and stable isotope dilution analysis (SIDA), in-cheese (13)C-labeling studies, followed by analysis of the γ-glutamyl transferase (GGT) activity revealed γ-GPs to be generated most efficiently after 24 months of ripening by a GGT-catalyzed transfer of the γ-glutamyl moiety of L-glutamine onto various acceptor amino acids released upon casein proteolysis. Following the identification of milk as a potential GGT source in PC, the functionality of the milk's GGT to generate the target γ-GPs was validated by stable isotope double-labeling (SIDL) experiments. Therefore, raw and heat-treated milk samples were incubated with L-glutamine-[U-(13)C] and acceptor amino acids (X) and the hetero- (γ-Glu-[(13)C5]-X) and homotranspeptidation products (γ-Glu-Gln-[(13)C10]) were quantitated by LC-MS/MS-SIDA using γ-Glu-Ala-[(13)C3] as the internal standard. High GGT activity to generate the γ-GPs and preference for L-phenylalanine and L-methionine as acceptor amino acids were found in raw milk and milk samples heat-treated for 10 min up to a maximum of 65 °C. In comparison, GGT activity and SIDL studies performed with inoculated Lactobacillus strains, including Lactobacillus harbinensis and Lactobacillus casei identified in PC by means of 16S rRNA gene sequencing, did not show any significant GGT activity and unequivocally demonstrated unpasteurized cow's milk, rather than microorganisms, as a key factor in γ-glutamyl dipeptide generation in Parmesan cheese.

  11. Quantitation using a stable isotope dilution assay (SIDA) and thresholds of taste-active pyroglutamyl decapeptide ethyl esters (PGDPEs) in sake.

    Science.gov (United States)

    Hashizume, Katsumi; Ito, Toshiko; Igarashi, Shinya

    2017-03-01

    A stable isotope dilution assay (SIDA) for two taste-active pyroglutamyl decapeptide ethyl esters (PGDPE1; (pGlu)LFGPNVNPWCOOC2H5, PGDPE2; (pGlu)LFNPSTNPWCOOC2H5) in sake was developed using deuterated isotopes and high-resolution mass spectrometry. Recognition thresholds of PGDPEs in sake were estimated as 3.8 μg/L for PGDPE1 and 8.1 μg/L for PGDPE2, evaluated using 11 student panelists aged in their twenties. Quantitated concentrations in 18 commercial sake samples ranged from 0 to 27 μg/L for PGDPE1 and from 0 to 202 μg/L for PGDPE2. The maximum levels of PGDPE1 and PGDPE2 in the sake samples were approximately 8 and 25 times higher than the estimated recognition thresholds, respectively. The results indicated that PGDPEs may play significant sensory roles in the sake. The level of PGDPEs in unpasteurized sake samples decreased during storage for 50 days at 6 °C, suggesting PGDPEs may be enzymatically decomposed.

  12. Fluid flow and water-rock interaction across the active Nankai Trough subduction zone forearc revealed by boron isotope geochemistry

    Science.gov (United States)

    Hüpers, Andre; Kasemann, Simone A.; Kopf, Achim J.; Meixner, Anette; Toki, Tomohiro; Shinjo, Ryuichi; Wheat, C. Geoffrey; You, Chen-Feng

    2016-11-01

    Compositional changes, dehydration reactions and fluid flow in subducted sediments influence seismogenesis and arc magmatism in subduction zones. To identify fluid flow and water-rock interaction processes in the western Nankai Trough subduction zone (SW Japan) we analyzed boron concentration and boron isotope composition (δ11B) of pore fluids sampled across the subduction zone forearc from depths of up to ∼922 m below seafloor during four Integrated Ocean Drilling Program (IODP) Expeditions. The major structural regimes that were sampled by coring include: (1) sedimentary inputs, (2) the frontal thrust zone, (3) the megasplay fault zone, and (4) the forearc basin. From mass balance consideration we find that consumption of boron (B) by ash alteration and desorption of B from the solid phase, mediated by organic matter degradation, produces a net decrease in B concentrations with depth down to ∼120 μM and variable δ11B values in the range of ∼+20‰ and +49‰. Interstitial water in sediments on the incoming oceanic plate are influenced by more efficient mobilization of exchangeable B from the solid phase due to higher temperatures and alteration of the oceanic crust that acts as a sink for 10B. At the tip of the megasplay fault zone, elevated B concentration and B isotopic composition suggest that underthrust coarse-grained slope sediments provide a pathway for fluids out of the upper (balance considerations suggest a shallower fluid source depth compared to pore fluids sampled previously near the décollement zone along the central portion of the Nankai margin.

  13. Identifying Low pH Active and Lactate-Utilizing Taxa within Oral Microbiome Communities from Healthy Children Using Stable Isotope Probing Techniques

    Energy Technology Data Exchange (ETDEWEB)

    McLean, Jeffrey S.; Fansler, Sarah J.; Majors, Paul D.; Mcateer, Kathleen; Allen, Lisa Z.; Shirtliff, Mark E.; Lux, Renate; Shi, Wenyuan

    2012-03-05

    Many human microbial infectious diseases including dental caries are polymicrobial in nature and how these complex multi-species communities evolve from a healthy to a diseased state is not well understood. Although many health- or disease-associated oral microbes have been characterized in vitro, their physiology in vivo in the presence of the complex oral microbiome is difficult to determine with current approaches. In addition, about half of these oral species remain uncultivated to date and little is known except their 16S rRNA sequence. Lacking culture-based physiological analyses, the functional roles of uncultivated microorganisms will remain enigmatic despite their apparent disease correlation. To start addressing these knowledge gaps, we applied a novel combination of in vivo Magnetic Resonance Spectroscopy (MRS) with RNA and DNA based Stable Isotope Probing (SIP) to oral plaque communities from healthy children for temporal monitoring of carbohydrate utilization, organic acid production and identification of metabolically active and inactive bacterial species.

  14. Stable isotope utilization methodology; Methodologie de l`emploi des isotopes stables

    Energy Technology Data Exchange (ETDEWEB)

    Roth, E. [Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)

    1994-12-31

    The various applications of stable isotope utilization are reviewed, as a function of their specific properties: poly-isotopic abundance modification is used for tracer applications; the accurate measurement of the stable isotope abundance may be applied to isotopic dilution for ultra-trace measurement, physical constant determination, fluid volume and concentration measurement; isotopic effects, such as reaction equilibrium differences are used for separation and identification of molecule active centers (pharmacology, paleoclimatology, hydrogeological studies) while reaction rate differences (competitive and non competitive methods) are used for the study of reaction mechanisms, such as enzymatic reactions. Analysis techniques (mass spectrometry, nuclear magnetic resonance, optical methods) are reviewed. 2 figs., 18 refs.

  15. Isotopic signatures associated with growth and metabolic activities of chemosynthetic nitrate-reducing microbes from deep-sea hydrothermal vents

    Science.gov (United States)

    Perez-Rodriguez, I. M.; Foustoukos, D.; Fogel, M. L.; Sievert, S. M.

    2013-12-01

    Epsilonproteobacteria and Aquificaceae have been identified as dominant members of microbial communities at deep-sea hydrothermal vents. Cultured representatives from these two groups appear to be mostly genetically wired to perform chemosynthesis at moderate-to-high temperatures (45 - 80oC) under anaerobic and sulfidic conditions. In this study we used Caminibacter mediatlanticus and Thermovibrio ammonificans as model organisms to constrain physiological parameters associated with dissimilatory nitrate reduction to ammonium (DNRA) in deep-sea vent Epsilonproteobacteria and Aquificaceae. We postulate that nitrate-based metabolic processes are of relevance for understanding primary production as well as nitrate mobilization in deep-sea vents. By constraining growth and respiration rates during DNRA, we observed that C. mediatlanticus achieved higher cell densities than T. ammonificans while exhibiting similar growth rates. DNRA kinetic rate constants and cell-specific nitrate reduction rates (csNRR) obtained from our data showed that within similar time frames T. ammonificans used 2.5 to 3 times as much nitrate than C. mediatlanticus and it did so ~3 times faster. However, the increased consumption of nitrate in T. ammonificans did not translate into higher growth yield. This is suggestive of either differential efficiencies in energy generating pathways or differential organic matter production (cell biomass versus extracellular organic material) associated with DNRA in these microorganisms. Nitrogen isotope fractionation for nitrate was similar for both organisms, with discrimination factors of ~ -5 to -6‰ for C. mediatlanticus and ~ -7 to -8‰ for T. ammonificans. Similar experiments performed under high hydrostatic pressure conditions (50 and 200 bar) showed that changes in pressure greatly affected both growth rates and DNRA kinetic rate constants in both microorganisms, however, δ15N discrimination factors for nitrate were not affected. This study provides

  16. Magnetostratigraphic dating of an intensification of glacial activity in the southern Italian Alps during Marine Isotope Stage 22

    Science.gov (United States)

    Muttoni, Giovanni; Ravazzi, Cesare; Breda, Marzia; Pini, Roberta; Laj, Carlo; Kissel, Catherine; Mazaud, Alain; Garzanti, Eduardo

    2007-01-01

    We applied magnetostratigraphy and mammal biostratigraphy to date climate-sensitive pollen cycles and lithostratigraphic units of the Pliocene-Pleistocene Leffe sedimentary succession from the Southern Alps, Italy. The Leffe section was correlated to additional sections (Casnigo, Fornaci di Ranica, and Pianengo) to construct a stratigraphic network along a common fluviatile system (the Serio River) sourced in the Southern Alps and flowing southward into the Po River Basin. We obtained a coherent scenario of climate variability for the last ˜ 2 Myr. At Leffe, lacustrine deposition commenced during the Olduvai Normal Subchron (1.94-1.78 Ma) and lasted up to a chronologic level compatible with Marine Isotope Stage (MIS) 22 (0.87 Ma). Pollen analysis revealed that climate varied cyclically from warm-temperate to cool during this time interval, but never as cold as during glacial intervals. At around MIS 22, climate cooled globally. Gravels, attributed to high-energy braided river systems fed locally by alluvial fans, prograded from the Serio River catchment area over the Leffe Basin and toward the Po Plain in response to a generalized event of vegetation withdrawal and enhanced physical erosion. At this time, Alpine valley glaciers reached their first maximum southward expansion with glacier fronts located at only ˜ 5 km upstream from Leffe.

  17. Isotopic effects on the phonon modes in boron carbide.

    Science.gov (United States)

    Werheit, H; Kuhlmann, U; Rotter, H W; Shalamberidze, S O

    2010-10-01

    The effect of isotopes ((10)B-(11)B; (12)C-(13)C) on the infrared- and Raman-active phonons of boron carbide has been investigated. For B isotopes, the contributions of the virtual crystal approximation, polarization vector and isotopical disorder are separated. Boron and carbon isotope effects are largely opposite to one another and indicate the share of the particular atoms in the atomic assemblies vibrating in specific phonon modes. Some infrared-active phonons behave as expected for monatomic boron crystals.

  18. Stable isotope studies

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  19. Possible influence of climate factors on the reconstruction of the cosmogenic isotope 14C production rate in the earth's atmosphere and solar activity in past epochs

    Science.gov (United States)

    Kuleshova, A. I.; Dergachev, V. A.; Kudryavtsev, I. V.; Nagovitsyn, Yu. A.; Ogurtsov, M. G.

    2015-12-01

    The paper considers the probable influence of variations of the global temperature and carbon dioxide concentration in the Earth's atmosphere on the results of reconstruction of the production rate of the cosmogenic isotope 14C in the terrestrial atmosphere for the period from the early 15th to the mid 19th century. This time interval covers the Spörer, Maunder, and Dalton minima of solar activity, as well as the Little Ice Age. It was shown that the climate changes that occurred during the Little Ice Age should be taken into account. In the Maunder and Spörer minima of solar activity, the 14C generation rate may be comparable to the values for the Dalton minimum, while exclusion of the climate effect yields extremely large values of the 14C production rate for these grand minima. In the solar activity reconstruction for past epochs, this circumstance should be taken into consideration via measurements of the 14C concentration on a long time scale.

  20. The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter

    Energy Technology Data Exchange (ETDEWEB)

    McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cleveland, Steven L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-03-01

    The 235U mass assay of bulk uranium items, such as oxide canisters, fuel pellets, and fuel assemblies, is not achievable by traditional gamma-ray assay techniques due to the limited penetration of the item by the characteristic 235U gamma rays. Instead, fast neutron interrogation methods such as active neutron coincidence counting must be used. For international safeguards applications, the most commonly used active neutron systems, the Active Well Coincidence Counter (AWCC), Uranium Neutron Collar (UNCL) and 252Cf Shuffler, rely on fast neutron interrogation using an isotopic neutron source [i.e., 252Cf or Am(Li)] to achieve better measurement accuracies than are possible using gamma-ray techniques for high-mass, high-density items. However, the Am(Li) sources required for the AWCC and UNCL systems are no longer manufactured, and newly produced systems rely on limited supplies of sources salvaged from disused instruments. The 252Cf shuffler systems rely on the use of high-output 252Cf sources, which while still available have become extremely costly for use in routine operations and require replacement every five to seven years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. In this work, we made use of Oak Ridge National Laboratory’s (ORNL’s) Large Volume Active Well Coincidence Counter (LV-AWCC) and a commercially available deuterium-deuterium (D-D) neutron generator to examine the potential of the D-D neutron generator as an alternative to the isotopic sources. We present the performance of the LV-AWCC with D-D generator for the assay of 235U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium (DU), low enriched uranium (LEU), and highly enriched uranium (HEU) items.

  1. Nickel isotopes and methanogens

    Science.gov (United States)

    Neubeck, A.; Ivarsson, M.

    2013-12-01

    Methanogens require Ni for their growth and as a consequence the microbial fractionation of Ni isotopes can be used as a biomarker for activity of methanogenic communities1. Anaerobic laboratory experiments was performed using methanogens to investigate methanogenic growth in a modified nutrient media2 with olivine Fo91 (5g/l) added as an additional mineral nutrient source and as the only H2 provider. One of the investigated methanogens showed an increased growth in the experiments with added olivine. There were also a close relationship between the mobilized Ni and the growth of the methanogen. Ni is an element that previously has been neglected in the study of fossilized microorganisms and their interaction with mineral substrates and, thus, there are no records or published data of Ni in association with microfossils. However, we have detected enrichments of Ni in fossilized microorganisms and ichno-fossils, respectively, from three separate locations. Ni is not present in the host rock in any of the samples. Thus, Ni is present in association with fossilized microorganisms from environments and more extensive analysis is required to understand the magnitude, uptake, preservation and fractionation of Ni in microfossils. In order to analyze Ni isotope fractionation from microbe-mineral interaction, we plan to use a high-resolution Laser-Ablation Time-of-Flight Mass Spectrometer (LMS)3. In situ profile ablation will provide detailed and localized data on fractionation patterns between microfossils and their host rock. Also, this technique will allow us to identify the change in Ni isotopic fractionation in rock samples caused by abiotic and biogenic processes in a faster and easier way and with less risk for contamination compared to the wet chemistry analyses of Ni isotopes. 1. Cameron, V., Vance, D., Archer, C. & House, C. H. A biomarker based on the stable isotopes of nickel. Proceedings of the National Academy of Sciences 106, 10944-10948 (2009). 2. Schn

  2. Measurement of O(6)-alkylguanine-DNA alkyltransferase activity in tumour cells using stable isotope dilution HPLC-ESI-MS/MS.

    Science.gov (United States)

    Sun, Guohui; Zhao, Lijiao; Fan, Tengjiao; Ren, Ting; Zhong, Rugang

    2016-10-15

    The repair of DNA mediated by O(6)-alkylguanine-DNA alkyltransferase (AGT) provides protection against DNA damage from endogenous or exogenous alkylation of the O(6) position of guanine. However, this repair acts as a double-edged sword in cancer treatment, as it not only protects normal cells from chemotherapy-associated toxicities, but also results in cancer cell resistance to guanine O(6)-alkylating antitumour agents. Thus, AGT plays an important role in predicting the individual susceptibility to guanine O(6)-alkylating carcinogens and chemotherapies. Accordingly, it is necessary to establish a quantitative method for determining AGT activity with high accuracy, sensitivity and practicality. Here, we describe a novel nonradioactive method for measuring AGT activity using stable isotope dilution high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). This method is based on the irreversibility of the removal of the O(6)-alkyl group from guanine by AGT and on the high affinity of O(6)-benzylguanine (O(6)-BG) as an AGT substrate. HPLC-ESI-MS/MS was used to measure the AGT activities in cell protein extracts from eight tumour lines, demonstrating that AGT activity was quite variable among different cell lines, ranging from nondetectable to 1021 fmol/mg protein. The experiments performed in intact tumour cells yielded similar results but exhibited slightly higher activities than those observed in cell protein extracts. The accuracy of this method was confirmed by an examination of AGT expression levels using western blotting analysis. To our knowledge, this method is the first mass spectrometry-based AGT activity assay, and will likely provide assistance in the screening of cancer risk or the application of chemotherapies.

  3. Chlorine isotope and Cl-Br fractionation in fluids of Poás volcano (Costa Rica): Insight into an active volcanic-hydrothermal system

    Science.gov (United States)

    Rodríguez, Alejandro; Eggenkamp, H. G. M.; Martínez-Cruz, María; van Bergen, Manfred J.

    2016-10-01

    Halogen-rich volcanic fluids issued at the surface carry information on properties and processes operating in shallow hydrothermal systems. This paper reports a long-term record of Cl-Br concentrations and δ37Cl signatures of lake water and fumaroles from the active crater of Poás volcano (Costa Rica), where surface expressions of magmatic-hydrothermal activity have shown substantial periodic changes over the last decades. Both the hyperacid water of its crater lake (Laguna Caliente) and subaerial fumaroles show significant temporal variability in Cl-Br concentrations, Br/Cl ratios and δ37Cl, reflecting variations in the mode and magnitude of volatile transfer. The δ37Cl signatures of the lake, covering the period 1985-2012, show fluctuations between + 0.02 ± 0.06‰ and + 1.15 ± 0.09‰. Condensate samples from adjacent fumaroles on the southern shore, collected during the interval (2010-2012) with strong changes in gas temperature (107-763°C), display a much larger range from - 0.43 ± 0.09‰ to + 14.09 ± 0.08‰. Most of the variations in Cl isotope, Br/Cl and concentration signals can be attributed to interaction between magma-derived gas and liquid water in the volcanic-hydrothermal system below the crater. The δ37Cl were lowest and closest to magmatic values in (1) fumarolic gas that experienced little or no interaction with subsurface water and followed a relatively dry pathway, and (2) water that captured the bulk of magmatic halogen output so that no phase separation could induce fractionation. In contrast, elevated δ37Cl can be explained by partial scavenging and fractionation during subsurface gas-liquid interaction. Hence, strong Cl isotope fractionation leading to very high δ37Cl in Poás' fumaroles indicates that they followed a wet pathway. Highest δ37Cl values in the lake water were found mostly in periods when it received a significant input from subaqueous fumaroles or when high temperatures and low pH caused HCl evaporation. It is

  4. The use of environmental monitoring as a technique to identify isotopic enrichment activities; O uso da monitoracao ambiental como tecnica de identificacao de atividades de enriquecimento isotopico

    Energy Technology Data Exchange (ETDEWEB)

    Buchmann, Jose Henrique

    2000-07-01

    The use of environmental monitoring as a technique to identify activities related to the nuclear fuel cycle has been proposed, by international organizations, as an additional measure to the safeguards agreements in force. The elements specific for each kind of nuclear activity, or nuclear signatures, inserted in the ecosystem by several transfer paths, can be intercepted with better or worse ability by different live organisms. Depending on the kind of signature of interest, the anthropogenic material identification and quantification require the choice of adequate biologic indicators and, mainly, the use of sophisticated techniques associated with elaborate sample treatments. This work demonstrates the technical viability of using pine needles as bioindicators of nuclear signatures associated with uranium enrichment activities. Additionally, it proposes the use of a technique widely diffused nowadays in the scientific community, the High Resolution Inductively Coupled Plasma Mass Spectrometer (HR-ICP-MS), to identify the signature corresponding to that kind of activities in the ecosystem. It can be also found a description of a methodology recently being applied in analytical chemistry,based on uncertainties estimates metrological concepts, used to calculate the uncertainties associated with the obtained measurement results. Nitric acid solutions with a concentration of 0.3 mol.kg{sup -1}, used to wash pine needles sampled near facilities that manipulate enriched uranium and containing only 0.1 {mu}g.kg{sup -1} of uranium, exhibit a {sup 235} U: {sup 238} U isotopic abundance ratio of 0.0092{+-}0.0002, while solutions originated from samples collected at places located more than 200 km far from activities related to the nuclear fuel cycle exhibit a value of 0.0074{+-}0.0002 for this abundance ratio. Similar results were obtained for samples collected in different places permit to confirm the presence of anthropogenic uranium and demonstrate the viability of using

  5. Utilization of radioanalytical methods for the determination of isotopes of U, Pu and Am in activated charcoal from IEA-R1 reactor

    Energy Technology Data Exchange (ETDEWEB)

    Geraldo, Bianca; Marumo, Julio T., E-mail: bgeraldo@ipen.br, E-mail: jtmarumo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Taddei, Maria Helena T., E-mail: mhtaddei@cnen.gov.br [Laboratorio de Pocos de Caldas (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil)

    2013-07-01

    Activated charcoal is a radioactive waste arising from the water purification system of the nuclear research reactor. The management of this waste includes its characterization in order to identify and quantify the existing radionuclides, including those known as 'difficult-to-measure radionuclides' (RDM). The analysis of these RDM usually involves complex radiochemical costly and time consuming procedures for the purification and separation of them. The objective of this work was to define a methodology of sequential analysis of isotopes of U, Pu and Am, present in activated charcoal, evaluating chemical recovery, analysis time, quantity of radioactive waste generated and cost. Ion exchange and the chromatographic extraction methodologies were compared. Both methods showed high chemical recoveries, ranged from 74 and 100% for U, 76 and 100% for Pu and 87 and 100% for Am, demonstrating that these methods provide accurate and reliable results. However, chromatographic extraction method is more suitable for the determination of the radionuclides because it generates the smaller volume of waste and is more cost-effectively. (author)

  6. A novel methodology to investigate isotopic biosignatures

    Science.gov (United States)

    Horner, T. J.; Lee, R. B. Y.; Henderson, G. M.; Rickaby, R. E. M.

    2012-04-01

    . coli (e.g. membranes, cytosol, etc.), including the catalytic metal atoms within CdCA. These experiments allow isotopic exchange reactions to be observed in biological systems at an unparalleled resolution, demonstrating that isotopic fractionation can occur, in vivo, on length scales as small as a few Å. We will explore future applications of this technique using the marine geochemistry of Cd as a case study. This experimental approach has great promise for studying the individual isotopic biosignatures of other biochemical reactions, in particular those which may have been active during early Earth History.

  7. Copper isotope fractionation by desert shrubs

    Energy Technology Data Exchange (ETDEWEB)

    Navarrete, Jesica U., E-mail: jnavarrete2@miners.utep.edu [University of Texas at El Paso, Department of Geological Sciences, 500 W. University Ave, El Paso, TX 79968 (United States); Viveros, Marian; Ellzey, Joanne T. [University of Texas at El Paso, Department of Biological Sciences, El Paso, TX 79968 (United States); Borrok, David M. [University of Texas at El Paso, Department of Geological Sciences, 500 W. University Ave, El Paso, TX 79968 (United States)

    2011-06-15

    Copper has two naturally occurring stable isotopes of masses 63 and 65 which can undergo mass dependent fractionation during various biotic and abiotic chemical reactions. These interactions and their resulting Cu isotope fractionations can be used to determine the mechanisms involved in the cycling of Cu in natural systems. In this study, Cu isotope changes were investigated at the organismal level in the metal-accumulating desert plant, Prosopis pubescens. Initial results suggest that the lighter Cu isotope was preferentially incorporated into the leaves of the plant, which may suggest that Cu was actively transported via intracellular proteins. The roots and stems show a smaller degree of Cu isotope fractionation and the direction and magnitude of the fractionations was dependent upon the levels of Cu exposure. Based on this and previous work with bacteria and yeast, a trend is emerging that suggests the lighter Cu isotope is preferentially incorporated into biological components, while the heavier Cu isotope tends to become enriched in aqueous solutions. In bacteria, plants and animals, intracellular Cu concentrations are strictly regulated via dozens of enzymes that can bind, transport, and store Cu. Many of these enzymes reduce Cu(II) to Cu(I). These initial results seem to fit into a broader picture of Cu isotope cycling in natural systems where oxidation/reduction reactions are fundamental in controlling the distributions of Cu isotopes.

  8. Quantification of ricin, RCA and comparison of enzymatic activity in 18 Ricinus communis cultivars by isotope dilution mass spectrometry.

    Science.gov (United States)

    Schieltz, David M; McWilliams, Lisa G; Kuklenyik, Zsuzsanna; Prezioso, Samantha M; Carter, Andrew J; Williamson, Yulanda M; McGrath, Sara C; Morse, Stephen A; Barr, John R

    2015-03-01

    The seeds of the Ricinus communis (Castor bean) plant are the source of the economically important commodity castor oil. Castor seeds also contain the proteins ricin and R. communis agglutinin (RCA), two toxic lectins that are hazardous to human health. Radial immunodiffusion (RID) and the enzyme linked immunosorbent assay (ELISA) are two antibody-based methods commonly used to quantify ricin and RCA; however, antibodies currently used in these methods cannot distinguish between ricin and RCA due to the high sequence homology of the respective proteins. In this study, a technique combining antibody-based affinity capture with liquid chromatography and multiple reaction monitoring (MRM) mass spectrometry (MS) was used to quantify the amounts of ricin and RCA independently in extracts prepared from the seeds of eighteen representative cultivars of R. communis which were propagated under identical conditions. Additionally, liquid chromatography and MRM-MS was used to determine rRNA N-glycosidase activity for each cultivar and the overall activity in these cultivars was compared to a purified ricin standard. Of the cultivars studied, the average ricin content was 9.3 mg/g seed, the average RCA content was 9.9 mg/g seed, and the enzymatic activity agreed with the activity of a purified ricin reference within 35% relative activity.

  9. Mechanism of Flavoprotein l-6-Hydroxynicotine Oxidase: pH and Solvent Isotope Effects and Identification of Key Active Site Residues.

    Science.gov (United States)

    Fitzpatrick, Paul F; Chadegani, Fatemeh; Zhang, Shengnan; Dougherty, Vi

    2017-02-14

    The flavoenzyme l-6-hydroxynicotine oxidase is a member of the monoamine oxidase family that catalyzes the oxidation of (S)-6-hydroxynicotine to 6-hydroxypseudooxynicotine during microbial catabolism of nicotine. While the enzyme has long been understood to catalyze oxidation of the carbon-carbon bond, it has recently been shown to catalyze oxidation of a carbon-nitrogen bond [Fitzpatrick, P. F., et al. (2016) Biochemistry 55, 697-703]. The effects of pH and mutagenesis of active site residues have now been utilized to study the mechanism and roles of active site residues. Asn166 and Tyr311 bind the substrate, while Lys287 forms a water-mediated hydrogen bond with flavin N5. The N166A and Y311F mutations result in ∼30- and ∼4-fold decreases in kcat/Km and kred for (S)-6-hydroxynicotine, respectively, with larger effects on the kcat/Km value for (S)-6-hydroxynornicotine. The K287M mutation results in ∼10-fold decreases in these parameters and a 6000-fold decrease in the kcat/Km value for oxygen. The shapes of the pH profiles are not altered by the N166A and Y311F mutations. There is no solvent isotope effect on the kcat/Km value for amines. The results are consistent with a model in which both the charged and neutral forms of the amine can bind, with the former rapidly losing a proton to a hydrogen bond network of water and amino acids in the active site prior to the transfer of hydride to the flavin.

  10. Photonuclear reactions on titanium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Belyshev, S. S. [Moscow State University (Russian Federation); Dzhilavyan, L. Z. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation); Ishkhanov, B. S.; Kapitonov, I. M. [Moscow State University (Russian Federation); Kuznetsov, A. A., E-mail: kuznets@depni.sinp.msu.ru; Orlin, V. N.; Stopani, K. A. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

    2015-03-15

    The photodisintegration of titanium isotopes in the giant-dipole-resonance energy region is studied by the photon-activation method. Bremsstrahlung photons whose spectrum has the endpoint energy of 55 MeV is used. The yields and integrated cross sections are determined for photoproton reactions on the titanium isotopes {sup 47,48,49,50}Ti. The respective experimental results are compared with their counterparts calculated on the basis of the TALYS code and a combined photonucleon-reaction model. The TALYS code disregards the isospin structure of the giant dipole resonance and is therefore unable to describe the yield of photoproton reactions on the heavy titanium isotopes {sup 49,50}Ti.

  11. Noble gas isotopic ratios from historical lavas and fumaroles at Mount Vesuvius (southern Italy): constraints for current and future volcanic activity

    Science.gov (United States)

    Tedesco, Dario; Nagao, Keisuke; Scarsi, Paolo

    1998-12-01

    Helium, neon and argon isotope ratios have been analysed from phenocrysts of eleven lava samples belonging to the last eruptive cycle of Mount Vesuvius (1631 until 1944). The phenocrysts separates include pyroxene ( N=10) and olivine ( N=1). All phenocryst samples show similarly low gas contents (He, Ne and Ar ˜10 -10 cm 3/g). 3He/ 4He ratios, 5.3-2.11 Ra, are generally low if compared to those typical of the MORB and those of the European Subcontinental Mantle (ESCM), respectively R/ Ra 8.5±1 and 6.0-6.5. A decreasing trend is found from 1631 to 1796, while a more homogeneous set of data is obtained for more recent eruptions, as evidenced by an average R/ Ra value of 2.85. Neon ratios ( 21Ne/ 22Ne and 20Ne/ 22Ne) strongly differ from those typically found on volcanoes and suggest that a crustal component has been added in the source region to Mt. Vesuvius magmas. Argon ratios ( 40Ar/ 36Ar and 38Ar/ 36Ar) have values similar to the atmosphere and are well correlated. The low 40Ar/ 36Ar ratio (max. 302) is, however, in the range of the 40Ar/ 36Ar ratios obtained from several lava samples at other Italian volcanoes and might be considered to have a deep origin. Two hypothesis have been discussed: (1) a deep argon-like-air source, due to subduction of air-rich sediments and/or (2) a preferential loss of Ar, in comparison to lighter noble gases, from silicic melts. Helium isotopic analysis of gas samples recently collected from crater and submarine fumaroles are similar to those of lavas belonging to the final part of this eruptive cycle. This result supports the idea that no new juvenile fluids from the source region have been injected into the magmatic reservoir during the 1631-1944 eruptive cycle and, more importantly, until 1993. Both sets of data help to understand the genesis of these fluids and to constrain the current activity of the volcano.

  12. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a m

  13. Isotopic and enzymatic analyses of planktonic nitrogen utilisation in the vicinity of Cape Sines (Portugal) during weak upwelling activity

    Science.gov (United States)

    Slawyk, Gerd; Coste, Bernard; Collos, Yves; Rodier, Martine

    1997-01-01

    Using measurements of 15N uptake and activities of nitrate reductase and glutamine synthetase, the utilization of nitrogenous nutrients by microplankton in the Portuguese upwelling area was investigated. During this cruise the euphotic zone of coastal waters was in most cases bisected by a nitracline forming two layers. Total inorganic nitrogen uptake rates (NH 4+ + NO 3-) in the upper mixed and nitrate-impoverished layer ranged from 0.1 to 0.8 nM h -1 and were primarily supported by regenerated (ammonium) nitrogen (62-97%), whereas they varied between 0.9 and 10.4 nM h -1 in the deep nitrate-rich layer and were mainly driven by new (nitrate) nitrogen (52-82%). Depth profiles of Chl a-specific uptake rates for ammonium and nitrate paralleled those of absolute uptake rates, i.e. values of VNH 4+Chl were highest (up to 16.1 nmol μg -1 h -1) in nitrate-poor surface waters while values of VNO 3-Chl were maximum (up to 8.4 nmol μg -1 h -1)within the nitracline. This latter vertical ordering of planktonic nitrogen nutrition was consistent with an aged upwelling situation. However, applying several indices of cell metabolism and nutritional status, such as 15N uptake/enzyme activity, surge uptake internally controlled uptake, and V maxChl/K t ratios, we were able to demonstrate that the phytoplankton assemblages inhabiting the nutrient-impoverished upper layer still bore the signature of physically mediated nitrogen (nitrate) supply generated by active upwelling that had occurred during the week before our visit to the area. This signature was the most evident in samples from the station furthest inshore and faded with distance from shore as a result of the deepening of the nitrate isopleths (weakening of upwelling activity), which showed the same offshore trend. The appearance of nitrate-rich waters at the surface, after a strong pulse of upwelling favourable winds just before the end of the cruise, led to a five-fold increase in average (over the euphotic zone

  14. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  15. Simultaneous analysis of oxybutynin and its active metabolite N-desethyl oxybutynin in human plasma by stable isotope dilution LC-MS/MS to support a bioequivalence study.

    Science.gov (United States)

    Sharma, Primal; Patel, Daxesh P; Sanyal, Mallika; Berawala, Hiren; Guttikar, Swati; Shrivastav, Pranav S

    2013-10-01

    An isotope dilution high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the simultaneous determination of oxybutynin and its pharmacologically active metabolite N-desethyl oxybutynin in human plasma. Extraction of oxybutynin, its metabolite and their deuterated analogs as internal standards (ISs) from 300 μL human plasma was carried out by liquid-liquid extraction with methyl tert-butyl ether-ethyl acetate solvent mixture. Chromatographic separation of analytes was performed on Cosmosil C18 (150 mm × 4.6 mm, 5 μm) column under isocratic conditions with acetonitrile-1.0mM ammonium acetate (90:10, v/v) as the mobile phase. Six endogenous plasma phospholipids (496.3/184.0, 524.3/184.0, 758.5/184.0, 786.5/184.0, 806.5/184.0 and 810.5/184.0) were monitored to determine the extraction efficiency under different extraction conditions. The precursor→product ion transition for both the analytes and ISs were monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring and positive ionization mode. The method was validated over a concentration range of 0.050-10.0 ng/mL for oxybutynin and 0.500-100 ng/mL for N-desethyl oxybutynin. The mean extraction recovery for analytes (80.4%) and ISs (76.9%) was consistent across five QC levels. Bench top, wet and dry extract, freeze-thaw and long term stability was evaluated for both the analytes. The method was applied to support a bioequivalence study of 5mg tablet formulation in 74 healthy Indian subjects. Assay reproducibility was demonstrated by reanalysis of 344 incurred samples.

  16. The estuarine geochemical reactivity of Zn isotopes and its relevance for the biomonitoring of anthropogenic Zn and Cd contaminations from metallurgical activities: Example of the Gironde fluvial-estuarine system, France

    Science.gov (United States)

    Petit, Jérôme C. J.; Schäfer, Jörg; Coynel, Alexandra; Blanc, Gérard; Chiffoleau, Jean-François; Auger, Dominique; Bossy, Cécile; Derriennic, Hervé; Mikolaczyk, Mathilde; Dutruch, Lionel; Mattielli, Nadine

    2015-12-01

    Zinc stable isotopes measurements by MC-ICP-MS, validated by laboratory intercalibrations, were performed on wild oysters, suspended particles and filtered river/estuarine water samples to provide new constraints for the use of Zn isotopes as environmental tracers. The samples selected were representative of the long range (400 km) transport of metal (Zn, Cd, etc.) contamination from former Zn-refining activities at Decazeville (i.e. δ66Zn > 1‰) and its phasing out, recorded during 30 years in wild oysters from the Gironde Estuary mouth (RNO/ROCCH sample bank). The study also addresses additional anthropogenic sources (urban and viticulture) and focuses on geochemical reactivity of Zn in the turbidity gradient and the maximum turbidity zone (MTZ) of the fluvial Gironde Estuary. In this area, dissolved Zn showed a strong removal onto suspended particulate matter (SPM) and progressive enrichment in heavy isotopes with increasing SPM concentrations varying from δ66Zn = -0.02‰ at 2 mg/L to +0.90‰ at 1310 mg/L. These signatures were attributed to kinetically driven adsorption due to strongly increasing sorption sites in the turbidity gradient and MTZ of the estuary. Oysters from the estuary mouth, contaminated sediments from the Lot River and SPM entering the estuary showed parallel historical evolutions (1979-2010) for Zn/Cd ratios but not for δ66Zn values. Oysters had signatures varying from δ66Zn = 1.43‰ in 1983 to 1.18‰ in 2010 and were offset by δ66Zn = 0.6-0.7‰ compared to past (1988) and present SPM from the salinity gradient. Isotopic signatures in river-borne particles entering the Gironde Estuary under contrasting freshwater discharge regimes during 2003-2011 showed similar values (δ66Zn ≈ 0.35 ± 0.03‰; 1SD, n = 15), i.e. they were neither related to former metal refining activities at least for the past decade nor clearly affected by other anthropogenic sources. Therefore, the Zn isotopic signatures in Gironde oysters reflect the

  17. Pb-Sr isotopic and geochemical constraints on sources and processes of lead contamination in well waters and soil from former fruit orchards, Pennsylvania, USA: A legacy of anthropogenic activities

    Science.gov (United States)

    Ayuso, Robert A.; Foley, Nora K.

    2016-01-01

    Isotopic discrimination can be an effective tool in establishing a direct link between sources of Pb contamination and the presence of anomalously high concentrations of Pb in waters, soils, and organisms. Residential wells supplying water containing up to 1600 ppb Pb to houses built on the former Mohr orchards commercial site, near Allentown, PA, were evaluated to discern anthropogenic from geogenic sources. Pb (n = 144) and Sr (n = 40) isotopic data and REE (n = 29) data were determined for waters from residential wells, test wells (drilled for this study), and surface waters from pond and creeks. Local soils, sediments, bedrock, Zn-Pb mineralization and coal were also analyzed (n = 94), together with locally used Pb-As pesticide (n = 5). Waters from residential and test wells show overlapping values of 206Pb/207Pb, 208Pb/207Pb and 87Sr/86Sr. Larger negative Ce anomalies (Ce/Ce*) distinguish residential wells from test wells. Results show that residential and test well waters, sediments from residential water filters in water tanks, and surface waters display broad linear trends in Pb isotope plots. Pb isotope data for soils, bedrock, and pesticides have contrasting ranges and overlapping trends. Contributions of Pb from soils to residential well waters are limited and implicated primarily in wells having shallow water-bearing zones and carrying high sediment contents. Pb isotope data for residential wells, test wells, and surface waters show substantial overlap with Pb data reflecting anthropogenic actions (e.g., burning fossil fuels, industrial and urban processing activities). Limited contributions of Pb from bedrock, soils, and pesticides are evident. High Pb concentrations in the residential waters are likely related to sediment build up in residential water tanks. Redox reactions, triggered by influx of groundwater via wells into the residential water systems and leading to subtle changes in pH, are implicated in precipitation of Fe oxyhydroxides

  18. The role of extracellular carbonic anhydrase activity in inorganic carbon utilization of Phaeocystis globosa (Prymnesiophyceae) : A comparison with other marine algae using the isotopic disequilibrium technique

    NARCIS (Netherlands)

    Elzenga, JTM; Prins, HBA; Stefels, J

    2000-01-01

    The utilization of inorganic carbon species by the marine microalga Phaeocystis globasa (Prymnesiophyceae) and several other algal species from different taxa, was investigated by determining the time course of C-14 incorporation in isotopic disequilibrium experiments. From these kinetic data, concl

  19. Laser Isotope Enrichment for Medical and Industrial Applications

    Energy Technology Data Exchange (ETDEWEB)

    Leonard Bond

    2006-07-01

    Laser Isotope Enrichment for Medical and Industrial Applications by Jeff Eerkens (University of Missouri), Jay Kunze (Idaho State University), and Leonard Bond (Idaho National Laboratory) The principal isotope enrichment business in the world is the enrichment of uranium for commercial power reactor fuels. However, there are a number of other needs for separated isotopes. Some examples are: 1) Pure isotopic targets for irradiation to produce medical radioisotopes. 2) Pure isotopes for semiconductors. 3) Low neutron capture isotopes for various uses in nuclear reactors. 4) Isotopes for industrial tracer/identification applications. Examples of interest to medicine are targets to produce radio-isotopes such as S-33, Mo-98, Mo-100, W-186, Sn-112; while for MRI diagnostics, the non-radioactive Xe-129 isotope is wanted. For super-semiconductor applications some desired industrial isotopes are Si-28, Ga-69, Ge-74, Se-80, Te-128, etc. An example of a low cross section isotope for use in reactors is Zn-68 as a corrosion inhibitor material in nuclear reactor primary systems. Neutron activation of Ar isotopes is of interest in industrial tracer and diagnostic applications (e.g. oil-logging). . In the past few years there has been a sufficient supply of isotopes in common demand, because of huge Russian stockpiles produced with old electromagnetic and centrifuge separators previously used for uranium enrichment. Production of specialized isotopes in the USA has been largely accomplished using old ”calutrons” (electromagnetic separators) at Oak Ridge National Laboratory. These methods of separating isotopes are rather energy inefficient. Use of lasers for isotope separation has been considered for many decades. None of the proposed methods have attained sufficient proof of principal status to be economically attractive to pursue commercially. Some of the authors have succeeded in separating sulfur isotopes using a rather new and different method, known as condensation

  20. Zircon U-Pb geochronology, geochemistry and Sr-Nd-Pb isotopes from the metamorphic basement in the Wuhe Complex: Implications for Neoarchean active continental margin along the southeastern North China Craton and constraints on the petrogenesis of Mesozoic granitoids

    Directory of Open Access Journals (Sweden)

    Andong Wang

    2013-01-01

    Full Text Available We report zircon U-Pb geochronology, geochemistry and Sr-Nd-Pb isotope data from mafic granulites and garnet amphibolites of the Wuhe Complex in the southeastern margin of the North China Craton (NCC. In combination with previous data, our results demonstrate that these rocks represent fragments of the ancient lower crust, and have features similar to those of the granulite basement in the northern margin of the NCC. A detailed evaluation of the Pb isotope data shows that Pb isotopes cannot effectively distinguish the role of the Yangtze Craton basement from that of the NCC basement with regard to the source and generation of magmas, at least for southeastern NCC. The age data suggest that the protoliths of the granulites or amphibolites in the Wuhe Complex were most likely generated in Neoarchean and that these rocks were subjected to Paleoproterozoic (1.8–1.9 Ga high-pressure granulite facies metamorphism. This study also shows that the Precambrian metamorphic basement in the southeastern margin of the NCC might have formed in a tectonic setting characterized by a late Neoarchean active continental margin.

  1. Discovery of the Cobalt Isotopes

    OpenAIRE

    Szymanski, T.; Thoennessen, M.

    2009-01-01

    Twenty-six cobalt isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  2. Discovery of the Arsenic Isotopes

    CERN Document Server

    Shore, A; Heim, M; Schuh, A; Thoennessen, M

    2009-01-01

    Twenty-nine arsenic isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  3. Isotope products manufacture in Russia and its prospects

    Energy Technology Data Exchange (ETDEWEB)

    Malyshev, S.V.; Okhotina, I.A.; Kalelin, E.A.; Krasnov, N.N.; Kuzin, V.V.; Malykh, J.A.; Makarovsky, S.B. [Tenex, Techsnabexport Co Ltd, Moscow (Russian Federation)

    1997-10-01

    At the present stage of the world economy development, stable and radioactive isotopes,preparations and products on their base are widely used in many fields of the national economy, medicine and scientific researches. The Russian Federation is one of the largest worldwide producers of a variety of nuclide products on the base of more than 350 isotopes, as follows: stable isotopes reactor, cyclotron, fission product radioactive isotopes, ion-radiation sources compounds, labelled with stable and radioactive isotopes, radionuclide short-lived isotope generators, radiopharmaceuticals, radionuclide light and heat sources; luminous paints on base of isotopes. The Russian Ministry for Atomic Energy coordinates activity for development and organization of manufacture and isotope products supply in Russia as well as for export. Within many years of isotope industry development, there have appeared some manufacturing centres in Russia, dealing with a variety of isotope products. The report presents the production potentialities of these centres and also an outlook on isotope production development in Russia in the next years

  4. Long-lasting Cadomian magmatic activity along an active northern Gondwana margin: U-Pb zircon and Sr-Nd isotopic evidence from the Brunovistulian Domain, eastern Bohemian Massif

    Science.gov (United States)

    Soejono, Igor; Janoušek, Vojtěch; Žáčková, Eliška; Sláma, Jiří; Konopásek, Jiří; Machek, Matěj; Hanžl, Pavel

    2016-11-01

    Cadomian magmatic complexes of the Brunovistulian Domain crop out at the eastern termination of the Bohemian Massif. However, the age, nature and geotectonic affinity of some of pre-Variscan (meta-)igneous rock complexes from this domain are still unknown. Geochronological and geochemical study of the granitic rocks across the Brunovistulian Domain reveals new information about the timing and nature of this magmatic activity originally situated along the northern margin of Gondwana. Zircon U-Pb data (601 ± 3 Ma, Brno Massif; 634 ± 6 Ma, paraautochtonous core of the Svratka Dome; 568 ± 3 Ma, Bíteš orthogneiss) from the allochtonous Moravicum indicate the prolonged magmatic activity within the Brunovistulian Domain during the Ediacaran. The major- and trace-element and Sr-Nd isotopic signatures show heterogeneous geochemical characteristics of the granitic rocks and suggest a magmatic-arc geotectonic setting. The two-stage Depleted Mantle Nd model ages (c. 1.3-2.0 Ga) indicate derivation of the granitic rocks from a relatively primitive crustal source, as well as from an ancient and evolved continental crust of the Brunovistulian Domain. These results constrain the magmatic-arc activity to c. 635-570 Ma and provide a further evidence for a long-lived (at least c. 65 Myr) and likely episodic subduction-related magmatism at the northern margin of Gondwana. The presence of granitic intrusions derived from variously mature crustal sources at different times suggests heterogeneous crustal segments to having been involved in the magmatic-arc system during its multistage evolution.

  5. Calculation of individual isotope equilibrium constants for geochemical reactions

    Science.gov (United States)

    Thorstenson, D.C.; Parkhurst, D.L.

    2004-01-01

    Theory is derived from the work of Urey (Urey H. C. [1947] The thermodynamic properties of isotopic substances. J. Chem. Soc. 562-581) to calculate equilibrium constants commonly used in geochemical equilibrium and reaction-transport models for reactions of individual isotopic species. Urey showed that equilibrium constants of isotope exchange reactions for molecules that contain two or more atoms of the same element in equivalent positions are related to isotope fractionation factors by ?? = (Kex)1/n, where n is the number of atoms exchanged. This relation is extended to include species containing multiple isotopes, for example 13C16O18O and 1H2H18O. The equilibrium constants of the isotope exchange reactions can be expressed as ratios of individual isotope equilibrium constants for geochemical reactions. Knowledge of the equilibrium constant for the dominant isotopic species can then be used to calculate the individual isotope equilibrium constants. Individual isotope equilibrium constants are calculated for the reaction CO2g = CO2aq for all species that can be formed from 12C, 13C, 16O, and 18O; for the reaction between 12C18 O2aq and 1H218Ol; and among the various 1H, 2H, 16O, and 18O species of H2O. This is a subset of a larger number of equilibrium constants calculated elsewhere (Thorstenson D. C. and Parkhurst D. L. [2002] Calculation of individual isotope equilibrium constants for implementation in geochemical models. Water-Resources Investigation Report 02-4172. U.S. Geological Survey). Activity coefficients, activity-concentration conventions for the isotopic variants of H2O in the solvent 1H216Ol, and salt effects on isotope fractionation have been included in the derivations. The effects of nonideality are small because of the chemical similarity of different isotopic species of the same molecule or ion. The temperature dependence of the individual isotope equilibrium constants can be calculated from the temperature dependence of the fractionation

  6. The production of stable isotopes in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Urgel, M.; Iglesias, J.; Casas, J.; Saviron, J. M.; Quintanilla, M.

    1965-07-01

    The activities developed in the field of the production of stable isotopes by means of ion-exchange chromatography and thermal diffusion techniques are reported. The first method was used to study the separation of the nitrogen and boron isotopes, whereby the separation factor was determined by the break through method. Values ranging from 1,028 to 1,022 were obtained for the separation factor of nitrogen by using ammonium hydroxide solutions while the corresponding values as obtained for boron amounted to 1,035-1,027 using boric acid solutions. Using ammonium chloride or acetate and sodium borate, respectively, resulted in the obtention of values for the separation factor approaching unity. The isotopic separation has been carried out according to the method of development by displacement. The separation of the isotopes of the noble gases, oxygen, nitrogen and carbon has been accomplished resorting to the method of thermal diffusion. (Author) 16 refs.

  7. Iron isotopic fractionation during continental weathering

    Energy Technology Data Exchange (ETDEWEB)

    Fantle, Matthew S.; DePaolo, Donald J.

    2003-10-01

    The biological activity on continents and the oxygen content of the atmosphere determine the chemical pathways through which Fe is processed at the Earth's surface. Experiments have shown that the relevant chemical pathways fractionate Fe isotopes. Measurements of soils, streams, and deep-sea clay indicate that the {sup 56}Fe/{sup 54}Fe ratio ({delta}{sup 56}Fe relative to igneous rocks) varies from +1{per_thousand} for weathering residues like soils and clays, to -3{per_thousand} for dissolved Fe in streams. These measurements confirm that weathering processes produce substantial fractionation of Fe isotopes in the modern oxidizing Earth surface environment. The results imply that biologically-mediated processes, which preferentially mobilize light Fe isotopes, are critical to Fe chemistry in weathering environments, and that the {delta}{sup 56}Fe of marine dissolved Fe should be variable and negative. Diagenetic reduction of Fe in marine sediments may also be a significant component of the global Fe isotope cycle. Iron isotopes provide a tracer for the influence of biological activity and oxygen in weathering processes through Earth history. Iron isotopic fractionation during weathering may have been smaller or absent in an oxygen-poor environment such as that of the early Precambrian Earth.

  8. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface...... deposited during the Early Ordovician — a time of known redox instability in ancient oceans – exhibit a significant positive Cr isotope excursion of +0.5‰. This excursion is interpreted as the reductive drawn down of dissolved Cr in seawater in response to the development of a proximal anoxic sink......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river water and to quantify...

  9. Lasers utilizing CO2 isotopes

    Science.gov (United States)

    Pechenin, Iu. V.; Domanov, M. S.

    1980-08-01

    The emission spectra and power characteristics of CW (C-12)(O-16)2, (C-13)(O-16)2, (C-12)(O-16)(O-18)2 and (C-12)(O-18) lasers are investigated. Laser output power is found to depend equally on the proportion of carbon and oxygen isotopes in the active medium for all isotopes except the asymmetrical (C-12)(O-16)(O-18), in which maximum output power is four to five times less due to the doubling of emission lines and limited enrichment caused by recombination into (C-12)(O-16)2 and (C-12)(O-18)2 molecules during discharge. The unsaturated gain is observed to increase linearly with enrichment, with that of nonsymmetrical molecules half that of the symmetrical molecules, while the maximum power output is independent of enrichment.

  10. Hydrothermal versus active margin sediment supply to the eastern equatorial Pacific over the past 23 million years traced by radiogenic Pb isotopes: Paleoceanographic and paleoclimatic implications

    Science.gov (United States)

    Höfig, Tobias W.; Hoernle, Kaj; Hauff, Folkmar; Frank, Martin

    2016-10-01

    We investigated the evolution of the Pb isotopic composition of bulk sediments on the Cocos Plate in sedimentary successions of Deep Sea Drilling Project (DSDP) Site 495 and Ocean Drilling Program/Integrated Ocean Drilling Program (ODP/IODP) Site 1256 over the past 23 million years of depositional history. Our study addresses the relationship of the sediment Pb isotope record to plate tectonics, weathering inputs, and paleoceanography. It is the first effort to characterize the Pb isotopic evolution of eastern equatorial Pacific sedimentation covering the entire tectonic pathway of the Cocos Plate from its formation at the East Pacific Rise to its arrival at the Central American subduction zone. The Sites 495 and 1256 bulk sediment Pb isotope records are fully consistent over time despite distinct differences between the type of sediment deposited at both locations. A systematic and continuous trend from ∼23 to ∼6-4 Ma toward more radiogenic Pb isotopic compositions, e.g., 206Pb/204Pb ratios increase from 18.29 to 18.81, reflects a decrease in the contribution of hydrothermal particles from the East Pacific Rise and an increase in the predominantly eolian contribution of mixed weathering products from the continental arcs of the Northern and south Central Andes as well as from southern Mexico. Surprisingly, both the Pb isotopic composition of the detrital fraction and that of past seawater indicate that inputs from nearby Central America and the Galápagos Archipelago did not significantly contribute to the sediments of our core locations but were overwhelmed by other sediment sources. A systematic change to less radiogenic Pb isotope ratios in sediments younger than ∼4-3 Ma, reaching present-day 206Pb/204Pb values near 18.70, reflects a reduction of the continental input from the South Central Volcanic Zone of the Andean Arc and increased contributions from southern Mexican igneous complexes. This isotopic trend reversal took place as a consequence of

  11. Isotope abundance ratios of sr in wine provenance determinations, in a tree-root activity study, and of pb in a pollution study on tree-rings.

    Science.gov (United States)

    Horn, P; Hölzl, S; Todt, W; Matthies, D

    1997-07-01

    Abstract In this contribution, the various and fundamentally different uses and applications of isotope signatures (of both heavy and light elements) are discussed. Examples are given for the successful use of (87)Sr/(86)Sr in uncovering fraud in wine trade. Also, in an experiment related to "Waldsterben", (87)Sr/(86)Sr analyses reveal rather unexpected responses of spruces and maple-trees to mechanical damage of their roots. In another study, from (206)Pb/(207)Pb (and (208)Pb/(207)Pb) analyses of tree growth-rings it is demonstrated that they do not accurately record lead burdens in the environment. This is contrary to current views on the subject of tree-rings as reliable banks of past heavy metal pollutions of the biosphere. Furthermore, new perspectives of applications of isotopes in biological tissues, including those of cosmogenic and nucleogenic origin will be shortly outlined.

  12. Estimation of the activity and isotopic composition of the fuel elements of the reactor in decaying; Estimacion de la actividad y composicion isotopica de los elementos combustibles del reactor en decaimiento

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar H, F. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2001-03-15

    At the present time its are had 59 fuel elements, 3 control bars with follower and 2 instrumented irradiated fuels that its are decaying in the pool of the reactor. The burnt one that its have these fuels is not uniform, the quantity of U-235 that contain at the moment it varies between 33.5 g up to 35.2 and its have a decay of at least 12 years. The burnt of the fuels was obtained with the CREMAT code, this burnt was takes like base to estimate the current isotopic inventory and the activity of the same ones using the ORIGEN2 code. (Author)

  13. Uranium isotopes fingerprint biotic reduction

    Science.gov (United States)

    Stylo, Malgorzata; Neubert, Nadja; Wang, Yuheng; Monga, Nikhil; Romaniello, Stephen J.; Weyer, Stefan; Bernier-Latmani, Rizlan

    2015-01-01

    Knowledge of paleo-redox conditions in the Earth’s history provides a window into events that shaped the evolution of life on our planet. The role of microbial activity in paleo-redox processes remains unexplored due to the inability to discriminate biotic from abiotic redox transformations in the rock record. The ability to deconvolute these two processes would provide a means to identify environmental niches in which microbial activity was prevalent at a specific time in paleo-history and to correlate specific biogeochemical events with the corresponding microbial metabolism. Here, we demonstrate that the isotopic signature associated with microbial reduction of hexavalent uranium (U), i.e., the accumulation of the heavy isotope in the U(IV) phase, is readily distinguishable from that generated by abiotic uranium reduction in laboratory experiments. Thus, isotope signatures preserved in the geologic record through the reductive precipitation of uranium may provide the sought-after tool to probe for biotic processes. Because uranium is a common element in the Earth’s crust and a wide variety of metabolic groups of microorganisms catalyze the biological reduction of U(VI), this tool is applicable to a multiplicity of geological epochs and terrestrial environments. The findings of this study indicate that biological activity contributed to the formation of many authigenic U deposits, including sandstone U deposits of various ages, as well as modern, Cretaceous, and Archean black shales. Additionally, engineered bioremediation activities also exhibit a biotic signature, suggesting that, although multiple pathways may be involved in the reduction, direct enzymatic reduction contributes substantially to the immobilization of uranium. PMID:25902522

  14. Perchlorate isotope forensics

    Science.gov (United States)

    Böhlke, J.K.; Sturchio, N.C.; Gu, B.; Horita, J.; Brown, G.M.; Jackson, W.A.; Batista, J.; Hatzinger, P.B.

    2005-01-01

    Perchlorate has been detected recently in a variety of soils, waters, plants, and food products at levels that may be detrimental to human health. These discoveries have generated considerable interest in perchlorate source identification. In this study, comprehensive stable isotope analyses ( 37Cl/35Cl and 18O/17O/ 16O) of perchlorate from known synthetic and natural sources reveal systematic differences in isotopic characteristics that are related to the formation mechanisms. In addition, isotopic analyses of perchlorate extracted from groundwater and surface water demonstrate the feasibility of identifying perchlorate sources in contaminated environments on the basis of this technique. Both natural and synthetic sources of perchlorate have been identified in water samples from some perchlorate occurrences in the United States by the isotopic method. ?? 2005 American Chemical Society.

  15. Isotope Production Facility (IPF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Los Alamos National Laboratory has produced radioactive isotopes for medicine and research since the mid 1970s, when targets were first irradiated using the 800...

  16. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  17. Isotopes in Greenland Precipitation

    DEFF Research Database (Denmark)

    Faber, Anne-Katrine

    the Arctic Ocean. A comprehensive database is created based on ice core and weather station data from Greenland within the period 1890-2014. Present day annual and seasonal mean values are computed for 326 locations in Greenland. Parameterization of the spatial distribution of temperature and δ18O are used...... of model and data can be used to improve the understanding of climate changes. This is done through analysis of isotope modelling, observations and ice core measurements. This dissertation comprises three projects: (1) Modelling the isotopic response to changes in Arctic sea surface conditions, (2......) Constructing a new Greenland database of observations and present-day ice core measurements, and (3) Performance test of isotope-enabled CAM5 for Greenland. The recent decades of rapid Arctic sea ice decline are used as a basis for an observational-based model experiment using the isotope-enabled CAM model 3...

  18. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, E.E.

    2004-11-15

    A review of recent research involving isotopically controlled semiconductors is presented. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, can be considered the most important one for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples. Manuel Cardona, the longtime editor-in-chief of Solid State Communications has been and continues to be one of the major contributors to this field of solid state physics and it is a great pleasure to dedicate this review to him.

  19. Isotopes through the looking glass

    Science.gov (United States)

    Mårtensson Pendrill, Ann Marie

    2000-08-01

    Nuclear distributions affect many aspects of atomic spectra. As an example, recent experimental results for the hyperfine anomaly in Fr isotopes are considered. These depend on nuclear charge and magnetization distributions. The variations in charge radii for these isotopes were studied earlier by measuring optical isotope shifts. The hyperfine anomalies for the odd-odd isotopes involve the neutron distributions, of interest for studies of parity nonconserving effects along a chain of isotopes.

  20. Methods of isotopic geochronology

    Science.gov (United States)

    Gorokhov, I. M.; Levchenkov, O. A.

    Papers are presented on such topics as the age of the chemical elements; the age of meteorites, the moon, and the earth; isotopic ages of the most ancient terrestrial formations; and the Archean evolution of Enderby Land in the Antarctic as evidenced by isotopic dating. Consideration is also given to a uranium-lead geochronology technique for investigating Precambrian ore deposits, a Pb-Pb technique of zircon dating, and the potentials and limitations of Sm-Nd geochronology.

  1. Oxygen Isotopes in Meteorites

    Science.gov (United States)

    Clayton, R. N.

    2003-12-01

    Oxygen isotope abundance variations in meteorites are very useful in elucidating chemical and physical processes that occurred during the formation of the solar system (Clayton, 1993). On Earth, the mean abundances of the three stable isotopes are 16O: 99.76%, 17O: 0.039%, and 18O: 0.202%. It is conventional to express variations in abundances of the isotopes in terms of isotopic ratios, relative to an arbitrary standard, called SMOW (for standard mean ocean water), as follows:The isotopic composition of any sample can then be represented by one point on a "three-isotope plot," a graph of δ17O versus δ18O. It will be seen that such plots are invaluable in interpreting meteoritic data. Figure 1 shows schematically the effect of various processes on an initial composition at the center of the diagram. Almost all terrestrial materials lie along a "fractionation" trend; most meteoritic materials lie near a line of "16O addition" (or subtraction). (4K)Figure 1. Schematic representation of various isotopic processes shown on an oxygen three-isotope plot. Almost all terrestrial materials plot along a line of "fractionation"; most primitive meteoritic materials plot near a line of "16O addition." The three isotopes of oxygen are produced by nucleosynthesis in stars, but by different nuclear processes in different stellar environments. The principal isotope, 16O, is a primary isotope (capable of being produced from hydrogen and helium alone), formed in massive stars (>10 solar masses), and ejected by supernova explosions. The two rare isotopes are secondary nuclei (produced in stars from nuclei formed in an earlier generation of stars), with 17O coming primarily from low- and intermediate-mass stars (shielding in the UV photodissociation of CO (van Dishoeck and Black, 1988). This process results from the large differences in abundance between C16O, on the one hand, and C17O and C18O on the other. Photolysis of CO occurs by absorption of stellar UV radiation in the

  2. Isotope Tales: Remaining Problems, Unsolvable Questions, and Gentle Successes

    Science.gov (United States)

    fogel, marilyn; bradley, christina; newsome, seth; filipp, fabian

    2014-05-01

    Earth's biomes function and adapt today as climate changes and ecosystems and the organisms within them adapt. Stable isotope biogeochemistry has had a major influence in understanding climate perturbations and continues to be an active area of research on many fronts. Banking on the success of compound specific stable isotope analyses of amino acids, nitrogen, carbon, and hydrogen isotopes continue to reveal subtle shifts in oceanic food webs and metabolic changes in microbes, plants, and animals. A biochemical understanding of exactly how organisms process and partition stable isotopes during metabolism remains unsolved, but is required if this field is to move beyond description to quantitation. Although the patterns of carbon and nitrogen isotopes are fairly well established in the common amino acids, we need to consider specifics: How do shifting metabolic pathways (metabolomics) influence the outcome of stable isotope partitioning? What influence does the gut microflora in animals have on isotopic labeling? What are the intramolecular isotope patterns of common amino acids and what do they tell us? What can be learned with other isotope systems, such as hydrogen? Results and ideas of how to move forward in this field will be presented starting at the molecular level and ending with ecosystems.

  3. Isotopic Evidence of Unaccounted for Fe and Cu Erythropoietic Pathways

    Science.gov (United States)

    Albarede, F.; Telouk, P.; Lamboux, A.; Jaouen, K.; Balter, V.

    2011-12-01

    Despite its potential importance for understanding perturbations in the Fe-Cu homeostatic pathways, the natural isotopic variability of these metals in the human body remains unexplored. We measured the Fe, Cu, and Zn isotope compositions of total blood, serum, and red blood cells of ~50 young blood donors by multiple-collector ICP-MS after separation and purification by anion exchange chromatography. Zn is on average 0.2 permil heavier in erythrocytes (δ 66Zn=0.44±0.33 permil) with respect to serum but shows much less overall isotopic variability than Fe and Cu, which indicates that isotope fractionation depends more on redox conditions than on ligand coordination. On average, Fe in erythrocytes (δ 56Fe=-2.59±0.47 permil) is isotopically light by 1-2 permil with respect to serum, whereas Cu in erythrocytes (δ 65Cu=0.56±0.50 permil) is 0.8 percent heavier. Fe and Cu isotope compositions clearly separate erythrocytes of men and women. Fe and Cu from B-type men erythrocytes are visibly more fractionated than all the other blood types. Isotope compositions provide an original method for evaluating metal mass balance and homeostasis. Natural isotope variability shows that the current models of Fe and Cu erythropoiesis, which assume that erythropoiesis is restricted to bone marrow, violate mass balance requirements. It unveils unsuspected major pathways for Fe, with erythropoietic production of isotopically heavy ferritin and hemosiderin, and for Cu, with isotopically light Cu being largely channeled into blood and lymphatic circulation rather than into superoxide dismutase-laden erythrocytes. Iron isotopes provide an intrinsic measuring rod of the erythropoietic yield, while Cu isotopes seem to gauge the relative activity of erythropoiesis and lymphatics.

  4. An examination of the H/D isotope substitution effect on selectivity and activity in the cavitating ultrasound hydrogenation of aqueous 3-buten-2-ol and 1,4-pentadien-3-ol on Pd-black

    Energy Technology Data Exchange (ETDEWEB)

    Boyles, Kelly R.; Chajkowski, Sarah M.; Disselkamp, Robert S.; Peden, Charles HF

    2006-05-24

    An H/D isotope effect study of the (H2 versus D2) hydrogenation of the aqueous substrates 3-buten-2-ol (3B2OL) and 1,4-pentadien-3-ol (14PD3OL) was performed using Pd-black catalyst. Either H2O or D2O solvents were employed (for alcohol H/D isotope substitution). Two experimental processing conditions of cavitating ultrasound (CUS) and stirred/silent (SS) methods were used. Products formed include 2-butanol and 2-butanone for the former, and 3-pentanol and 3-pentanone for the latter. The observed selectivity and pseudo-first order reaction rate coefficients (e.g., activity) to these products enabled a mechanistic interpretation of the various reaction conditions to be proposed. Experiments utilized a 50 mL batch reactor maintained at 298 K, employed 5.4 atm of H2 or D2 gas, while seven aliquots were collected during the course of the reaction. We have utilized 1-propanol as an inert dopant in all experiments to enable the rapid onset of cavitation in the CUS systems as described earlier [R.S. Disselkamp et al., J. Catal., 227, 552 (2004)]. The following conclusions were noted. First, the activity of the CUS compared to SS processing were ~100-fold larger. Second, variable catalyst loading experiments for stirred/silent D2 hydrogenation processing indicated that mass transfer of hydrogen gas to the Pd-surface played a role such that higher catalyst loading reduced surface D-atom concentrations and reduced saturated alcohol formation (e.g., via reduced H-addition to surface alkyl radicals). Third, for CUS processing the ketone selectivities for experiments employing water compared to D2O indicated that 3B2OL were twice as large, whereas for 14PD3OL they were comparable. This suggests, somewhat surprisingly, that for 3B2OL enol tautomerization to ketone is a slow, and possibly rate-controlling, process. Finally, again for CUS processing, the similarity in ketone selectivities (all ~17%) for H2 compared to D2 hydrogenation for both 3B2OL and 14PD3OL suggest that both H

  5. Isotope geochemistry. Biological signatures in clumped isotopes of O₂.

    Science.gov (United States)

    Yeung, Laurence Y; Ash, Jeanine L; Young, Edward D

    2015-04-24

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of "clumped" isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in (18)O(18)O and (17)O(18)O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling.

  6. Expression of accessory colonization factor subunit A (ACFA) of Vibrio cholerae and ACFA fused to cholera toxin B subunit in transgenic tomato (Solanum lycopersicum).

    Science.gov (United States)

    Sharma, Manoj Kumar; Jani, Dewal; Thungapathra, M; Gautam, J K; Meena, L S; Singh, Yogendra; Ghosh, Amit; Tyagi, Akhilesh Kumar; Sharma, Arun Kumar

    2008-05-20

    In earlier study from our group, cholera toxin B subunit had been expressed in tomato for developing a plant-based vaccine against cholera. In the present investigation, gene for accessory colonization factor (acf) subunit A, earlier reported to be essential for efficient colonization in the intestine, has been expressed in Escherichia coli as well as tomato plants. Gene encoding for a chimeric protein having a fusion of cholera toxin B subunit and accessory colonization factor A was also expressed in tomato to generate more potent combinatorial antigen. CaMV35S promoter with a duplicated enhancer sequence was used for expression of these genes in tomato. Integration of transgenes into tomato genome was confirmed by PCR and Southern hybridization. Expression of the genes was confirmed at transcript and protein levels. Accessory colonization factor A and cholera toxin B subunit fused to this protein accumulated up to 0.25% and 0.08% of total soluble protein, respectively, in the fruits of transgenic plants. Whereas protein purified from E. coli, in combination with cholera toxin B subunit can be used for development of conventional subunit vaccine, tomato fruits expressing these proteins can be used together with tomato plants expressing cholera toxin B subunit for development of oral vaccine against cholera.

  7. Stable isotopes. Applications and production; Les isotopes stables. Applications - production

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, S.; Louvet, P.; Soulie, E. [eds.

    1994-12-31

    This conference presents 46 communications concerning stable isotope production, utilization and application, grouped in 6 sessions and posters. The various themes are: biological applications (pharmacology, medical diagnosis, metabolism and protein studies, toxicity and response studies, labelled compounds), analysis procedures (NMR analysis for macromolecules, tracer studies), nuclear applications (utilization of stable isotopes in nuclear reactors), biological, physical and chemical applications (mass transfer, mobility, crystallography, isotopic exchange), stable isotope production (ion chromatography, ion cyclotron resonance, cryogenic distillation).

  8. Deformation of C isotopes

    CERN Document Server

    Kanada-Enyo, Y

    2004-01-01

    Systematic analysis of the deformations of proton and neutron densities in even-even C isotopes was done based on the method of antisymmetrized molecular dynamics. The $E2$ transition strength was discussed in relation to the deformation. We analyze the $B(E2;2^+_1\\to 0^+_1)$ in $^{16}$C, which has been recently measured to be abnormally small. The results suggest the difference of the deformations between proton and neutron densities in the neutron-rich C isotopes. It was found that stable proton structure in C isotopes plays an important role in the enhancement the neutron skin structure as well as in the systematics of $B(E2)$ in the neutron-rich C.

  9. Earth Processes: Reading the Isotopic Code

    Science.gov (United States)

    Basu, Asish; Hart, Stan

    Publication of this monograph will coincide, to a precision of a few per mil, with the centenary of Henri Becquerel's discovery of "radiations actives" (C. R. Acad. Sci., Feb. 24, 1896). In 1896 the Earth was only 40 million years old according to Lord Kelvin. Eleven years later, Boltwood had pushed the Earth's age past 2000 million years, based on the first U/Pb chemical dating results. In exciting progression came discovery of isotopes by J. J. Thomson in 1912, invention of the mass spectrometer by Dempster (1918) and Aston (1919), the first measurement of the isotopic composition of Pb (Aston, 1927) and the final approach, using Pb-Pb isotopic dating, to the correct age of the Earth: close—2.9 Ga (Gerling, 1942), closer—3.0 Ga (Holmes, 1949) and closest—4.50 Ga (Patterson, Tilton and Inghram, 1953).

  10. Isotopes in Condensed Matter

    CERN Document Server

    G Plekhanov, Vladimir

    2013-01-01

    This book provides a concise introduction to the newly created sub-discipline of solid state physics isotopetronics. The role of isotopes in materials and their properties are describe  in this book. The problem of the enigma of the atomic mass in microphysics is briefly discussed.  The range of the applications of isotopes is wide: from biochemical process in living organisms to modern technical applications in quantum information. Isotopetronics promises to improve nanoelectronic and optoelectronic devices. With numerous illustrations this book is useful to researchers, engineers and graduate students.

  11. Isotope hydrology: applied discipline in earth sciences; Hydrologie isotope: une discipline des sciences de la terre

    Energy Technology Data Exchange (ETDEWEB)

    Froehlich, K.; Rozanski, K.; Araguas Araguas, L. [Isotope Hydrology Section, International Atomic Agency, Vienna (Austria)

    1998-12-31

    The discipline `isotope hydrology` is being reviewed from the perspective of the Isotope Hydrology Section of the International Atomic Energy Agency in Vienna. The Section was created in the late fifties and is activities involved int the scientific progress of the discipline. The role of the IAEA in the development of isotope hydrology has always been of a dual nature: on one hand, the Section has been and still is heavily engaged in supporting and coordinating further development of isotope methodologies, on the other hand, it serves as an interface between the methodological development in research institutes and the applied work using proven techniques in field projects on water resources assessment and management. The paper provides a brief overview of applications of isotope-based methodologies in hydrology, with emphasis on new trends and challenges related to man`s growing impact on the water cycle. This contribution is a tribute to the memory of the former Head of the Isotope Hydrology Section, Jean-Charles Fontes, to whom we owe so much. (authors) 30 refs.

  12. Sulfur isotope signatures in gypsiferous sediments of the Estancia and Tularosa Basins as indicators of sulfate sources, hydrological processes, and microbial activity

    Science.gov (United States)

    Szynkiewicz, Anna; Moore, Craig H.; Glamoclija, Mihaela; Pratt, Lisa M.

    2009-10-01

    In order to reconstruct paleo-environmental conditions for the saline playa lakes of the Rio Grande Rift, we investigated sediment sulfate sources using sulfur isotope compositions of dissolved SO42- ions in modern surface water, groundwater, and SO42- precipitated in the form of gypsum sediments deposited during the Pleistocene and Holocene in the Tularosa and Estancia Basins. The major sulfate sources are Lower and Middle Permian marine evaporites (δ 34S of 10.9-14.4‰), but the diverse physiography of the Tularosa Basin led to a complex drainage system which contributed sulfates from various sources depending on the climate at the time of sedimentation. As inferred from sulfur isotope mass balance constraints, weathering of sulfides of magmatic/hydrothermal and sedimentary origin associated with climate oscillations during Last Glacial Maximum contributed about 35-50% of the sulfates and led to deposition of gypsum with δ 34S values of -1.2‰ to 2.2‰ which are substantially lower than Permian evaporates. In the Estancia Basin, microbial sulfate reduction appears to overprint sulfur isotopic signatures that might elucidate past groundwater flows. A Rayleigh distillation model indicates that about 3-18% of sulfates from an inorganic groundwater pool (δ 34S of 12.6-13.8‰) have been metabolized by bacteria and preserved as partially to fully reduced sulfur-bearing minerals species (elemental sulfur, monosulfides, disulfides) with distinctly negative δ 34S values (-42.3‰ to -20.3‰) compared to co-existing gypsum (-3.8‰ to 22.4‰). For the Tularosa Basin microbial sulfate reduction had negligible effect on δ 34S value of the gypsiferous sediments most likely because of higher annual temperatures (15-33 °C) and lower organic carbon content (median 0.09%) in those sediments leading to more efficient oxidation of H 2S and/or smaller rates of sulfate reduction compared to the saline playas of the Estancia Basin (5-28 °C; median 0.46% of organic carbon

  13. Discoveries of isotopes by fission

    Indian Academy of Sciences (India)

    M Thoennessen

    2015-09-01

    Of the about 3000 isotopes presently known, about 20% have been discovered in fission. The history of fission as it relates to the discovery of isotopes as well as the various reaction mechanisms leading to isotope discoveries involving fission are presented.

  14. Isotopic Implicit Surface Meshing

    NARCIS (Netherlands)

    Boissonnat, Jean-Daniel; Cohen-Steiner, David; Vegter, Gert

    2004-01-01

    This paper addresses the problem of piecewise linear approximation of implicit surfaces. We first give a criterion ensuring that the zero-set of a smooth function and the one of a piecewise linear approximation of it are isotopic. Then, we deduce from this criterion an implicit surface meshing algor

  15. Forensic Stable Isotope Biogeochemistry

    Science.gov (United States)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  16. Isotope hydrograph separation

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, P. [UFZ-Umweltforschungszentrum, Centre of Environmental Research Leipzig-Halle, Leipzig (Germany)

    2000-07-01

    Storm-runoff thus reflects the complex hydraulic behaviour of drainage basins and water-links of such systems. Water of different origin may participate in the events and in this lecture, the application of isotope techniques to separate storm hydrographs into different components will be presented.

  17. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20072750 Huang Sijing(State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China);Pei Changrong Age Calibration for the Boundary between Lower and Middle Triassic by Strontium Isotope Stratigraphy in Eastern Sichuan Province

  18. GEOCHRONOMETRY ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正>20040631 Chen Jiangfeng (School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui) ; Xie Zhi Relationships Between Rb-Sr, Ar - Ar Geochronometers and Oxygen Isotopic Equilibrium of Intrusions from Eastern Anhui Province, China (Geological Journal of China Universities, ISSN 1006 - 7493, CN 32 -

  19. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20090432 Zhou Shuqing (School of Energy Resources, China University of Geosciences Beijing 100083, China); Huang Haiping Stable Isotopic Records vs. Important Events in Life Evolution and the Concurrent Environment (Geological Review, ISSN0371-5736, CN11-1952, 54(2), 2008, p.225-231, 3 illus., 1 table, 77 refs.)

  20. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20141014Wang Hairan(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an710069,China);Zhao Hongge Theory and Application of Zircon U-Pb Isotope Dating Technique(Geology and Resources,ISSN1671-1947,CN21-1458/P,22(3),2013,p.229

  1. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20070454 Bao Zengkuan (Institute of High Energy Physics, CAS, Beijing 100049, China); Yuan Wanming Apatite (U-Th)/He Dating and Its Application (Acta Petrologica et Mineralogica, ISSN1000-6524, CN11-1966/P, 24(2), 2005, p.126-132, 2 illus., 25 refs.) Key words: isotopic geochronology

  2. Isotopic constraints on biogeochemical cycling of copper in the ocean.

    Science.gov (United States)

    Takano, Shotaro; Tanimizu, Masaharu; Hirata, Takafumi; Sohrin, Yoshiki

    2014-12-05

    Trace elements and their isotopes are being actively studied as powerful tracers in the modern ocean and as proxies for the palaeocean. Although distributions and fractionations have been reported for stable isotopes of dissolved Fe, Cu, Zn and Cd in the ocean, the data remain limited and only preliminary explanations have been given. Copper is of great interest because it is either essential or toxic to organisms and because its distribution reflects both biological recycling and scavenging. Here we present new isotopic composition data for dissolved Cu (δ(65)Cu) in seawater and rainwater. The Cu isotopic composition in surface seawater can be explained by the mixing of rain, river and deep seawater. In deep seawater, δ(65)Cu becomes heavier with oceanic circulation because of preferential scavenging of the lighter isotope ((63)Cu). In addition, we constrain the marine biogeochemical cycling of Cu using a new box model based on Cu concentrations and δ(65)Cu.

  3. Embryotoxicity of stable isotopes and use of stable isotopes in studies of teratogenetic mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Spielmann, H.; Nau, H.

    1986-07-01

    Experiments on teratogenic effects of stable isotopes from our own and other laboratories are evaluated. In the first series of investigations, the enrichment of the stable isotope /sup 13/C derived from U-/sup 13/C-glucose was studied in mouse embryos at various stages of development, including limb buds in organ culture. Preimplantation mouse embryos incubated in vitro in /sup 13/C-enriched medium for 48 hours showed normal development during subsequent differentiation in vitro and also in vivo after embryo transfer to faster mothers. These embryos were 15% to 20% enriched in /sup 13/C. Administration of U-13-C-glucose to pregnant mice during organogenesis led to an increase of the absolute /sup 13/C content of the embryo for several days after the end of isotope administration, whereas the enrichment in maternal tissue decreased. No alterations of embryonic development were detected due to stable isotope enrichment. Development of cultured mouse limb buds was unaffected by incubation with 82 mol% U-/sup 13/C-glucose as judged from morphologic and biochemical criteria. The second part of the article describes the value of deuterium-labeled drugs as probes into the mechanism of activation of teratogenic metabolites. A comparison of the pharmacokinetics as well as the teratogenicity between cyclophosphamide and some specific deuterium-labeled analogues showed that the isotope effect observed can be related to a particular metabolic pathway crucial for teratogenic activation by this drug.

  4. Novel Molecular Insights into Classical and Alternative Activation States of Microglia as Revealed by Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC)-based Proteomics.

    Science.gov (United States)

    Bell-Temin, Harris; Culver-Cochran, Ashley E; Chaput, Dale; Carlson, Christina M; Kuehl, Melanie; Burkhardt, Brant R; Bickford, Paula C; Liu, Bin; Stevens, Stanley M

    2015-12-01

    Microglia, the resident immune cells of the brain, have been shown to display a complex spectrum of roles that span from neurotrophic to neurotoxic depending on their activation status. Microglia can be classified into four stages of activation, M1, which most closely matches the classical (pro-inflammatory) activation stage, and the alternative activation stages M2a, M2b, and M2c. The alternative activation stages have not yet been comprehensively analyzed through unbiased, global-scale protein expression profiling. In this study, BV2 mouse immortalized microglial cells were stimulated with agonists specific for each of the four stages and total protein expression for 4644 protein groups was quantified using SILAC-based proteomic analysis. After validating induction of the various stages through a targeted cytokine assay and Western blotting of activation states, the data revealed novel insights into the similarities and differences between the various states. The data identify several protein groups whose expression in the anti-inflammatory, pro-healing activation states are altered presumably to curtail inflammatory activation through differential protein expression, in the M2a state including CD74, LYN, SQST1, TLR2, and CD14. The differential expression of these proteins promotes healing, limits phagocytosis, and limits activation of reactive nitrogen species through toll-like receptor cascades. The M2c state appears to center around the down-regulation of a key member in the formation of actin-rich phagosomes, SLP-76. In addition, the proteomic data identified a novel activation marker, DAB2, which is involved in clathrin-mediated endocytosis and is significantly different between M2a and either M1 or M2b states. Western blot analysis of mouse primary microglia stimulated with the various agonists of the classical and alternative activation states revealed a similar trend of DAB2 expression compared with BV2 cells.

  5. Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems

    Science.gov (United States)

    Ni, Yunyan; Ma, Qisheng; Ellis, Geoffrey S.; Dai, Jinxing; Katz, Barry; Zhang, Shuichang; Tang, Yongchun

    2011-05-01

    Based on quantum chemistry calculations for normal octane homolytic cracking, a kinetic hydrogen isotope fractionation model for methane, ethane, and propane formation is proposed. The activation energy differences between D-substitute and non-substituted methane, ethane, and propane are 318.6, 281.7, and 280.2 cal/mol, respectively. In order to determine the effect of the entropy contribution for hydrogen isotopic substitution, a transition state for ethane bond rupture was determined based on density function theory (DFT) calculations. The kinetic isotope effect (KIE) associated with bond rupture in D and H substituted ethane results in a frequency factor ratio of 1.07. Based on the proposed mathematical model of hydrogen isotope fractionation, one can potentially quantify natural gas thermal maturity from measured hydrogen isotope values. Calculated gas maturity values determined by the proposed mathematical model using δD values in ethane from several basins in the world are in close agreement with similar predictions based on the δ 13C composition of ethane. However, gas maturity values calculated from field data of methane and propane using both hydrogen and carbon kinetic isotopic models do not agree as closely. It is possible that δD values in methane may be affected by microbial mixing and that propane values might be more susceptible to hydrogen exchange with water or to analytical errors. Although the model used in this study is quite preliminary, the results demonstrate that kinetic isotope fractionation effects in hydrogen may be useful in quantitative models of natural gas generation, and that δD values in ethane might be more suitable for modeling than comparable values in methane and propane.

  6. Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems

    Science.gov (United States)

    Ni, Y.; Ma, Q.; Ellis, G.S.; Dai, J.; Katz, B.; Zhang, S.; Tang, Y.

    2011-01-01

    Based on quantum chemistry calculations for normal octane homolytic cracking, a kinetic hydrogen isotope fractionation model for methane, ethane, and propane formation is proposed. The activation energy differences between D-substitute and non-substituted methane, ethane, and propane are 318.6, 281.7, and 280.2cal/mol, respectively. In order to determine the effect of the entropy contribution for hydrogen isotopic substitution, a transition state for ethane bond rupture was determined based on density function theory (DFT) calculations. The kinetic isotope effect (KIE) associated with bond rupture in D and H substituted ethane results in a frequency factor ratio of 1.07. Based on the proposed mathematical model of hydrogen isotope fractionation, one can potentially quantify natural gas thermal maturity from measured hydrogen isotope values. Calculated gas maturity values determined by the proposed mathematical model using ??D values in ethane from several basins in the world are in close agreement with similar predictions based on the ??13C composition of ethane. However, gas maturity values calculated from field data of methane and propane using both hydrogen and carbon kinetic isotopic models do not agree as closely. It is possible that ??D values in methane may be affected by microbial mixing and that propane values might be more susceptible to hydrogen exchange with water or to analytical errors. Although the model used in this study is quite preliminary, the results demonstrate that kinetic isotope fractionation effects in hydrogen may be useful in quantitative models of natural gas generation, and that ??D values in ethane might be more suitable for modeling than comparable values in methane and propane. ?? 2011 Elsevier Ltd.

  7. High-Resolution Records of the Holocene Paleoenvironmental Variation Reflected by Carbonate and Its Isotopic Compositions in Bosten Lake and Response to Glacial Activities

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chengjun; ZHENG Mianping; Alexander PROKOPENKO; Steffen MISCHKE; GOU Xiaohui; YANG Qili; ZHANG Wanyi; FENG Zhaodong

    2009-01-01

    The Early Holocene paleoclimate in Bosten Lake on the northern margin of the Tarim Basin, southern Xinjiang, is reconstructed through an analysis of a 953 cm long core (BSTC2000) taken from Bosten Lake. Multiple proxies of this core, including the mineral components of carbonate, carbonate content, stable isotopic compositions of carbonate, Ca/Sr, TOC and C/N and C/S of organic matter, are used to reconstruct the climatic change since 8500 a B.P. The chronology model is made by nine AMS ~(14)C ages of leaves, seeds and organic matter contained in two parallel cores. The climate was cold and wet during 8500 to 8100 a B.P. Temperature increased from 8100 to 6400 a B.P., the climate was warm and humid, and the lake expanded. The lake level was highest during this stage. Then from 6400 to 5100 a B.P., the climate became cold and the lake level decreased slightly. During the late mid-Holocene, the climate was hot and dry from 5100 to 3100 a B.P., but there was a short cold period during 4400 to 3800 a B.P. At this temporal interval, a mass of ice and snow melting water supplied the lake at the early time and made the lake level rise. The second highest lake level stage occurred during 5200 to 3800 a B.P. The climate was cool and wet during 3100 to 2200 a B.P., when the lake expanded with decreasing evaporation. The lake had the last short-term high level during 3100 to 2800 a B.P. After this short high lake level period, the lake shrank because of the long-term lower temperature and reduced water supply. From 2200 to 1200 a B.P., the climate was hot and dry, and the lake shrank greatly. Although the temperature decreased somewhat from 1200 a B.P. to the present, the climate was warm and dry. The lake level began to rise a little again, but it did not reach the river bed altitude of the Konqi River, an outflow river of the Bosten Lake.

  8. GEOCHRONOMETRY &ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131727 Huang Xiaowen(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550002,China);Qi Liang Preliminary Study on Sample-Preparation for Re-Os Isotopic Dating of Pyrite(Geochimica,ISSN0379-1726,CN44-1398/P,41(4),2012,p.380-386,3illus.,2tables,25refs)Key words:pyrite,Re-Os dating

  9. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    <正>20050934 Chen Zhihong (Chinese Academy of Geological Sciences, Beijing 100037, China); Lu Songnian Age of the Fushui Intermediate-Mafic Intrusive Complex in the Qinling Orogen, New Zircon U - Pb and Whole -Rock Sm and Nd Isotope Chronological Evidence (Geological Bulletin of China, ISSN 1671-2552, CN11-4648/P, 23(4), 2004, p. 322-328, 3 illus. , 3 tables, 10 refs. )

  10. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20132601 Cui Yurong(Tianjin Institute of Geology and Mineral Resources,China Geological Survey,Tianjin 300170,China);Zhou Hongying In Situ LA-MC-ICP-MS U-Pb Isotopic Dating of Monazite(Acta Geoscientica Sinica,ISSN0375-5444,CN11-1856/P,33(6),2012,p.865-876,6illus.,4tables,41refs.)Key words:monazite,U-Pb dating

  11. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  12. Stable isotopic signature of Australian monsoon controlled by regional convection

    Science.gov (United States)

    Zwart, C.; Munksgaard, N. C.; Kurita, N.; Bird, M. I.

    2016-11-01

    The aim of this study was to identify the main meteorological drivers of rainfall isotopic variation in north Australia in order to improve the interpretation of isotopic proxy records in this region. An intense monitoring program was conducted during two monsoonal events that showed significant and systematic isotopic change over time. The results showed a close link between isotopic variation in precipitation and variability in monsoon conditions, associated with the presence of large convective envelopes propagating through the study site. The largest negative amplitudes in the isotopic signal were observed when eastward and westward moving precipitation systems within the convective envelope merged over the measurement site. This suggests that the amplitude of the isotopic signal is related to the size and activity of the convective envelope. The strong correlation between rainfall isotopic variation, regional outgoing longwave radiation and regional rainfall amount supports this conclusion. This is further strengthened by the strong relationship between isotopic variation and the integrated rainfall history of air masses prior to arriving at the measurement locations. A local amount effect was not significant and these findings support the interpretation of δ18O as proxy for regional climatic conditions rather than local rainfall amount. Meteorological parameters that characterize intra-seasonal variability of monsoon conditions were also found to be strongly linked to inter-seasonal variability of the monthly based δ18O values in the Global Network of Isotopes in Precipitation (GNIP) database. This leads to the conclusion that information about the Australian monsoon variability can likely be inferred from the isotopic proxy record in North Australia on short (intra seasonal) and long (inter seasonal or longer) timescales.

  13. Nuclear physics and stable isotopes; Physique nucleaire et isotopes stables

    Energy Technology Data Exchange (ETDEWEB)

    Goutte, D. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee

    1994-12-31

    The aim of this paper is to show that fundamental research in nuclear physics requires utilization of stable isotopes; stable isotopes are essential as target material since a large quantity of nucleus have to be studied in order to appreciate all the complexity of the nuclear structure, but also as a tool, such as beams, for the same purpose. Examples are given with samarium, tin and germanium isotopes. 7 figs.

  14. Influence of isotopic re-equilibration on speleothem and fluid inclusion isotope ratios after primary calcite precipitation

    Science.gov (United States)

    Kluge, Tobias; Haderlein, Astrid; Weißbach, Therese

    2016-04-01

    quantitative estimates of oxygen isotope exchange rates and to infer the dimension of the actively participating molecular layer at the surface of the calcite mineral. References: Mavromatis, V., Bundeleva, I.A., Shirokova, L.S., Millo, C., Pokrovsky, P.S., Benezeth, P., Ader, M., Oelkers, E.H., 2015. The continuous re-equilibration of carbon isotope compositions of hydrous Mg carbonates in the presence of cyanobacteria. Chem Geol., 404, 41-51. Oelkers, E. H., Berning, U.-N., Rinder, T., Mavromatis, V., Perez-Fernandez, A., Pogge von Strandmann, P., 2015. Rapid isotopic fractionation among minerals and fluids during dissolution, precipitation, and at equilibrium. Goldschmidt abstracts, 2318.

  15. Lithium isotope separation by laser

    Energy Technology Data Exchange (ETDEWEB)

    Arisawa, T.; Maruyama, Y.; Suzuki, Y.; Shiba, K.

    1982-01-01

    A lithium isotope separation was performed using a laser isotope separation method. It was found that the lithium atoms with a natural isotopic abundance enhanced its /sup 6/Li concentration up to over 90% by tuning the laser wavelength to the /sup 2/Psub(1/2) of /sup 6/Li. Too high power, however, leads to a loss of enrichment due to the power broadening effect which was analysed by the equation of motion of density matrices.

  16. Hydrogen Isotope Exchange Properties of Porous Solids Containing Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    HEUNG, LEUNGK.

    2004-08-18

    Porous solids such as activated alumina, silica and molecular sieves generally contain significant amounts of hydrogen atoms in the form of H2O or OH even at high temperature and low humidity environment. A significant amount of this hydrogen is available for reversible isotopic exchange. This exchange reaction is slow under normal conditions and does not render itself to practical applications. But if the exchange kinetics is improved this reaction has the potential to be used for tritium removal from gas streams or for hydrogen isotopic separation.The use of catalysts to improve the exchange kinetics between hydrogen isotope in the gas phase and that in the solid phase was investigated. Granules of alumina, silica and molecular sieve were coated with platinum or palladium as the catalyst. The granules were packed in a 2-cm diameter column for isotope exchange tests. Gas streams containing different concentrations of deuterium in nitrogen or argon were fed through the protium saturated column. Isotope concentration in column effluent was monitored to generate isotope break-through curves. The curves were analyzed to produce information on the kinetics and capacity of the material. The results showed that all materials tested provided some extent of isotope exchange but some were superior both in kinetics and capacity. This paper will present the test results.

  17. Argon isotope fractionation induced by stepwise heating

    Science.gov (United States)

    Trieloff, Mario; Falter, Martina; Buikin, Alexei I.; Korochantseva, Ekaterina V.; Jessberger, Elmar K.; Altherr, Rainer

    2005-03-01

    Noble gas isotopes are widely used to elucidate the history of the rocks in which they have been trapped, either from distinct reservoirs or by accumulation following radioactive decay. To extract noble gases from their host rocks, stepwise heating is the most commonly used technique to deconvolve isotopically different components, e.g., atmospheric, in situ radiogenic, or excess radiogenic from mantle or crustal reservoirs. The accurate determination of the isotopic composition of these different components is of crucial importance, e.g., for ages obtained by 40Ar- 39Ar stepheating plateaus. However, diffusion theory-based model calculations predict that the stepwise thermal extraction process from mineral phases induces isotope fractionation and, hence, adulterates the original composition. Such effects are largely unconsidered, as they are small and a compelling experimental observation is lacking. We report the first unequivocal evidence for significant mass fractionation of argon isotopes during thermal extraction, observed on shungite, a carbon-rich Precambrian sedimentary rock. The degree of fractionation, as monitored by 38Ar/ 36Ar and 40Ar/ 36Ar ratios, very well agrees with theoretical predictions assuming an inverse square root dependence of diffusion coefficient and atomic mass, resulting in easier extraction of lighter isotopes. Hence, subatmospheric 40Ar/ 36Ar ratios obtained for argon extracted at low temperatures may not represent paleoatmospheric argon. Shungite argon resembles modern atmospheric composition, but constraints on the timing of trapping appear difficult to obtain, as shungites are multicomponent systems. In 40Ar- 39Ar stepwise heating, the isotope fractionation effect could cause systematic underestimations of plateau ages, between 0.15 and 0.4% depending on age, or considerably higher if samples contain appreciable atmospheric Ar. The magnitude of this effect is similar to the presently achieved uncertainties of this increasingly

  18. Cold regions isotope applications

    Energy Technology Data Exchange (ETDEWEB)

    Perrigo, L.D.; Divine, T.E.

    1976-04-01

    Pacific Northwest Laboratories (PNL) started the Cold Regions Isotope Applications Program in FY-1975 to identify special conditions in the Arctic and similar geographic areas (Cold Regions) where radioisotope power, heater, or sterilization systems would be desirable and economically viable. Significant progress was made in the first year of this program and all objectives for this initial 12-month period were achieved. The major conclusions and recommendations resulting for this effort are described below. The areas of interest covered include: radiosterilization of sewage; heating of septic tanks; and radioisotope thermoelectric generators as power sources for meteorological instruments and navigational aids. (TFD)

  19. Low order H∞ optimal control for ACFA blended wing body aircraft

    Science.gov (United States)

    Haniš, T.; Kucera, V.; Hromčík, M.

    2013-12-01

    Advanced nonconvex nonsmooth optimization techniques for fixed-order H∞ robust control are proposed in this paper for design of flight control systems (FCS) with prescribed structure. Compared to classical techniques - tuning of and successive closures of particular single-input single-output (SISO) loops like dampers, attitude stabilizers, etc. - all loops are designed simultaneously by means of quite intuitive weighting filters selection. In contrast to standard optimization techniques, though (H2, H∞ optimization), the resulting controller respects the prescribed structure in terms of engaged channels and orders (e. g., proportional (P), proportional-integral (PI), and proportional-integralderivative (PID) controllers). In addition, robustness with regard to multimodel uncertainty is also addressed which is of most importance for aerospace applications as well. Such a way, robust controllers for various Mach numbers, altitudes, or mass cases can be obtained directly, based only on particular mathematical models for respective combinations of the §ight parameters.

  20. Si Isotopes of Brownleeite

    Science.gov (United States)

    Nakamura-Messenger, K.; Messenger, Scott R.; Ito, M.; Keller, L. P.; Clemett, S. J.; Jones, J. H.; Tatsuoka, H.; Zolensky, M. E.; Tatsuoka, H.

    2010-01-01

    Brownleeite is a manganese silicide, ideally stoichiometric MnSi, not previously observed in nature until its discovery within an interplanetary dust particle (IDP) that likely originated from a comet [1]. Three discrete brownleeite grains in the IDP L2055 I3 (4 microns in size, hereafter IDP I3) were identified with maximum dimensions of 100, 250 and 600 nm and fully analyzed using scanning-transmission electron microscopy (STEM) [1]. One of the grains (100 nm in size) was poikilitically enclosed by low-Fe, Mn-enriched (LIME) olivine. LIME olivine is epitaxial to the brownleeite with the brownleeite (200) parallel to the olivine c* [1]. LIME olivine is an enigmatic phase first reported from chondritic porous IDPs and some unequilibrated ordinary chondrites [ 2], that is commonly observed in chondritic-porous IDPs. Recently, LIME olivine has been also found in comet Wild-2 (Stardust) samples [3], indicating that LIME olivine is a common mineral component of comets. LIME olivine has been proposed to form as a high temperature condensate in the protosolar nebula [2]. Brownleeite grains also likely formed as high-temperature condensates either in the early Solar System or in the outflow of an evolved star or supernova explosion [1]. The isotopic composition of the brownleeite grains may strongly constrain their ultimate source. To test this hypothesis, we performed isotopic analyses of the brownleeite and the associated LIME olivine, using the NASA/JSC NanoSIMS 50L ion microprobe.

  1. Worldwide lead-isotope ratio in bivalves and sediments

    DEFF Research Database (Denmark)

    Larsen, Martin Mørk; Jacobsen, Gitte; Strand, Jakob;

    The lead-isotope ratio have been used to assess and identify impact of leaded gasoline, coal combustion and  mineral activities[ref 1] due to the difference in 206Pb (~52%), 207Pb (~24%) and 208Pb (~23%) isotope ratios. The source of these differences is the decaying of the parent isotopes of 238U...... to 206Pb, 235U to 207Pb and 232Th to 208Pb. 204Pb is the only stable Pb isotope usually contributing 1% of the total Pb. Differences in 206Pb/207Pb ratio ranges from 1.06 to 1.10 in old Pb ores (e.g. the time of the roman empire), whereas recent mining from radiogenic (high U and Th contents) ores can...

  2. Calcium isotopes in wine

    Science.gov (United States)

    Holmden, C. E.

    2011-12-01

    The δ 44/40Ca values of bottled wine vary between -0.76% to -1.55% on the seawater scale and correlate weakly with inverse Ca concentration and Mg/Ca ratio, such that the lowest δ 44/40Ca values have the highest Ca concentrations and lowest Mg/Ca ratios. The correlation is notable in the sense that the measured wines include both whites and reds sampled from different wine growing regions of the world, and cover a wide range of quality. Trends among the data yield clues regarding the cause of the observed isotopic fractionation. White wines, and wines generally perceived to be of lower quality, have lower δ 44/40Ca values compared to red wines and wines of generally perceived higher quality. Quality was assessed qualitatively through sensory evaluation, price, and scores assigned by critics. The relationship between δ 44/40Ca and wine quality was most apparent when comparing wines of one varietal from one producer from the same growing region. In the vineyard, wine quality is related to factors such as the tonnage of the crop and the ripeness of the grapes at the time of harvesting, the thickness of the skins for reds, the age of the vines, as well as the place where the grapes were grown (terroir). Quality is also influenced by winemaking practices such as fermentation temperature, duration of skin contact, and barrel ageing. Accordingly, the relationship between δ 44/40Ca and wine quality may originate during grape ripening in the vineyard or during winemaking in the cellar. We tested the grape ripening hypothesis using Merlot grapes sampled from a vineyard in the Okanagan, British Columbia, using sugar content (degrees Brix) as an indicator of ripeness. The grapes were separated into pulp, skin, and pip fractions and were analyzed separately. Thus far, there is no clear evidence for a systematic change in δ 44/40Ca values associated with progressive ripening of grapes in the vineyard. On the day of harvesting, the δ 44/40Ca value of juice squeezed from

  3. CO/sub 2/-isotope lasers

    Energy Technology Data Exchange (ETDEWEB)

    Pechenin, Yu.V.; Domanov, M.S.

    1980-08-01

    The emission spectra and power characteristics of CW (C-12)(O-16)2, (C-13)(O-16)2, (C-12)(O-16)(O-18)2 and (C-12)(O-18) lasers are investigated. Laser output power is found to depend equally on the proportion of carbon and oxygen isotopes in the active medium for all isotopes except the asymmetrical (C-12)(O-16)(O-18), in which maximum output power is four to five times less due to the doubling of emission lines and limited enrichment caused by recombination into (C-12)(O-16)2 and (C-12)(O-18)2 molecules during discharge. The unsaturated gain is observed to increase linearly with enrichment, with that of nonsymmetrical molecules half that of the symmetrical molecules, while the maximum power output is independent of enrichment.

  4. Activation cross sections of proton and deuteron induced nuclear reactions on holmium and erbium, related to the production of $^{161}$Er and $^{160}$Er medical isotopes

    CERN Document Server

    Tárkányi, F; Takács, S; Hermanne, A; Baba, M

    2016-01-01

    Experimental excitation functions for long-lived products in proton induced reactions were measured with the activation method in the 37-65 MeV energy range on natural holmium. Stacked foil irradiation technique and high resolution gamma spectrometry were used in order to measure cross-section data for the production of $^{161}$Er, $^{160}$Er and $^{159,157}$Dy. For comparison of the production routes of medically related $^{161}$Er and $^{160}$Er radioisotopes new experimental cross section data were deduced for the $^{162}$Er(p,x)$^{161,160}$Er and $^{162}$Er(d,x)$^{161,160}$Er reactions by re-evaluating gamma-ray spectra from earlier measurements. No earlier data were found in the literature for these reactions. The experimental data are compared with results of TALYS theoretical code reported in TENDL-2015.

  5. Activation cross sections of proton and deuteron induced nuclear reactions on holmium and erbium, related to the production of (161)Er and (160)Er medical isotopes.

    Science.gov (United States)

    Tárkányi, F; Ditrói, F; Takács, S; Hermanne, A; Baba, M

    2016-09-01

    Experimental excitation functions for long-lived products in proton induced reactions were measured with the activation method in the 37-65MeV energy range on natural holmium. Stacked foil irradiation technique and high resolution gamma spectrometry were used in order to measure cross-section data for the production of (161)Er, (160)Er and (1)(59,157)Dy. For comparison of the production routes of medically related (161)Er and (160)Er radioisotopes new experimental cross section data were deduced for the (162)Er(p,x)(161,160)Er and (162)Er(d,x)(161,160)Er reactions by re-evaluating gamma-ray spectra from earlier measurements. No earlier data were found in the literature for these reactions. The experimental data are compared with results of TALYS theoretical code reported in TENDL-2015.

  6. Determination of plutonium isotopes in seawater reference materials using isotope-dilution ICP-MS.

    Science.gov (United States)

    Zheng, Jian; Yamada, Masatoshi

    2012-09-01

    We analyzed the activities of (239)Pu, (240)Pu, (239+240)Pu, (241)Pu, the ratio of number of atoms (atom ratio) for (240)Pu/(239)Pu, and the activity ratio of (241)Pu/(239+240)Pu in seawater reference materials, IAEA-443 and IAEA-381, using a highly sensitive isotope dilution sector field inductively coupled plasma mass spectrometry method. With a mean chemical yield of 65% determined with (242)Pu as a tracer, we found that the experimentally established values in IAEA-443 for (239)Pu, (240)Pu, (241)Pu and (239+240)Pu activities are almost the same as those in IAEA-381. Regarding the (239+240)Pu activity, we provided the most precise and accurate result among the twelve laboratories, which participated in the interlaboratory comparison. In addition, for the (240)Pu/(239)Pu atom ratio, our results for IAEA-381 (0.2315±0.0008) and IAEA-443 (0.2325±0.0008) are in good agreement with the IAEA information value (0.229±0.006), but have much smaller uncertainty. Since the new seawater reference material, IAEA-443, is commercially available, it can be used not only for method validation for seawater plutonium isotope ratio and activity analysis, but also for more general use as a plutonium isotope standard for mass discrimination correction for other environmental samples.

  7. Radium isotopes in the lower Mississippi River

    Science.gov (United States)

    Kraemer, T. F.; Curwick, P. B.

    1991-02-01

    Radium isotopes have been measured in Mississippi River water at several locations between St. Francisville and Venice, Louisiana. Measured activities averaged 11.1 dpm/100 L (disintegrations per minute per 100 L) for dissolved 226Ra with a 228Ra/226Ra activity ratio of 1.04 and a 224Ra/228Ra activity ratio of 1.06 for the section of river above a phosphogypsum waste-discharge input. Down river from this site, the dissolved 226Ra activity averaged 22.4 dpm/100 L with a 228Ra/226Ra activity ratio of 0.55 and a 224Ra/228Ra activity ratio of 0.87. Chemical and isotopic reequilibration of the radium in the waste with that in the river water and suspended sediments occurs very rapidly. Fluxes of 226Ra are calculated to be 2.44×1014 dpm/yr (disintegrations per minute per year) for the main stem of the Mississippi during phosphogypsum disposal compared to 0.98×1014 dpm/yr when no phosphogypsum disposal is occurring. 28Ra flux is calculated to be 1.06×1014 dpm/yr during disposal and 1.01×1014 dpm/yr in the absence of disposal. The radium flux is estimated to be 45% in the dissolved state and 55% in the adsorbed state.

  8. Competition from Isotopic Modelling

    Directory of Open Access Journals (Sweden)

    Virginie Fabre

    2011-01-01

    Full Text Available During later MOIS3, in Europe two populations were present, autochthonous Neanderthals and modern humans. Ecological competition between these two populations has often been evoked but never demonstrated. Our aim is to establish whether resource competition occurred. In this paper, in order to examine the possibility of ecological competition between these two populations, 599 isotopic data were subjected to rigorous statistical treatment and analysis through mixing models. The aim of this paper was to compare dietary strategies of Neanderthals and modern humans over time. Our conclusions suggest that Neanderthals and modern humans shared dietary habits in the particular environmental context of MOIS3 characterised in Europe by climatic deterioration. In this environmental context, the resource competition between Neanderthals and modern humans may have accelerated the disappearance of the Neanderthal population.

  9. Isotope Effects in ESR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Werner Herrmann

    2013-06-01

    Full Text Available In order to present the relationship between ESR spectroscopy and isotope effects three levels are considered: (i ESR spectroscopy is described on a general level up to the models for interpretation of the experimental spectra, which go beyond the usually used time and mass independent spin-Hamilton operator, (ii the main characteristics of the generalized isotope effects are worked out, and finally (iii the basic, mainly quantum mechanical effects are used to describe the coupling of electron spins with the degrees of freedom, which are accessible under the selected conditions, of the respective paramagnetic object under investigation. The ESR parameters and the respective models are formalized so far, that they include the time and mass depending influences and reflect the specific isotope effects. Relations will be established between the effects in ESR spectra to spin relaxation, to spin exchange, to the magnetic isotope effect, to the Jahn-Teller effects, as well as to the influence of zero-point vibrations. Examples will be presented which demonstrate the influence of isotopes as well as the kind of accessible information. It will be differentiated with respect to isotope effects in paramagnetic centres itself and in the respective matrices up to the technique of ESR imaging. It is shown that the use of isotope effects is indispensable in ESR spectroscopy.

  10. Production of stable isotopes utilizing the plasma separation process

    Science.gov (United States)

    Bigelow, T. S.; Tarallo, F. J.; Stevenson, N. R.

    2005-12-01

    A plasma separation process (PSP) is being operated at Theragenics Corporation's®, Oak Ridge, TN, facility for the enrichment of stable isotopes. The PSP utilizes ion cyclotron mass discrimination to separate isotopes on a relatively large scale. With a few exceptions, nearly any metallic element could be processed with PSP. Output isotope enrichment factor depends on natural abundance and mass separation and can be fairly high in some cases. The Theragenics™ PSP facility is believed to be the only such process currently in operation. This system was developed and formerly operated under the US Department of Energy Advanced Isotope Separation program. Theragenics™ also has a laboratory at the PSP site capable of harvesting the isotopes from the process and a mass spectrometer system for analyzing enrichment and product purity. Since becoming operational in 2002, Theragenics™ has utilized the PSP to separate isotopes of several elements including: dysprosium, erbium, gadolinium, molybdenum and nickel. Currently, Theragenics™ is using the PSP for the separation of 102Pd, which is used as precursor for the production of 103Pd. The 103Pd radioisotope is the active ingredient in TheraSeed®, which is used in the treatment of early stage prostate cancer and being investigated for other medical applications. New industrial, medical and research applications are being investigated for isotopes that can be enriched on the PSP. Pre-enrichment of accelerator or reactor targets offers improved radioisotope production. Theragenics operates 14 cyclotrons for proton activation and has access to HFIR at ORNL for neutron activation of radioisotopes.

  11. Compelling Research Opportunities using Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-04-23

    Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies and diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1

  12. Carbon isotope geochemistry and geobiology

    Science.gov (United States)

    Desmarais, D.

    1985-01-01

    Carbon isotope fractionation values were used to understand the history of the biosphere. For example, plankton analyses confirmed that marine extinctions at the end of the Cretaceous period were indeed severe (see Hsu's article in Sundquist and Broeker, 1984). Variations in the isotopic compositions of carbonates and evaporitic sulfates during the Paleozoic reflect the relative abundances of euxinic (anoxic) marine environments and organic deposits from terrestrial flora. The carbon isotopic composition of Precambrian sediments suggest that the enzyme ribulose bisphosphate carboxylase has existed for perhaps 3.5 billion years.

  13. Isotope-edited infrared spectroscopy.

    Science.gov (United States)

    Buchner, Ginka S; Kubelka, Jan

    2012-01-01

    Isotope-edited infrared (IR) spectroscopy is a powerful tool for studying structural and dynamical properties of peptides and proteins with site-specific resolution. Labeling of selected amide carbonyls with (13)C results in detectable sidebands of amide I' vibrations, which provide information about local conformation and/or solvent exposure without structural perturbation to the protein. Incorporation of isotopically labeled amino acids at specific positions is achieved by the chemical synthesis of the studied proteins. We describe the basic procedures for synthesis of (13)C isotopically edited protein samples, experimental IR spectroscopic measurements, and analysis of the site-specific structural changes from the thermal unfolding IR data.

  14. Uranium Isotope Ratios in Modern and Precambrian Soils

    Science.gov (United States)

    DeCorte, B.; Planavsky, N.; Wang, X.; Auerbach, D. J.; Knudsen, A. C.

    2015-12-01

    Uranium isotopes (δ238U values) are an emerging paleoredox proxy that can help to better understand the redox evolution of Earth's surface environment. Recently, uranium isotopes have been used to reconstruct ocean and atmospheric redox conditions (Montoya-Pino et al., 2010; Brennecka et al., 2011; Kendall et al., 2013; Dahl et al., 2014). However, to date, there have not been studies on paleosols, despite that paleosols are, arguably better suited to directly tracking the redox conditions of the atmosphere. Sedimentary δ238U variability requires the formation of the soluble, oxidized form of U, U(VI). The formation of U(VI) is generally thought to require oxygen levels orders of magnitude higher than prebiotic levels. Without significant U mobility, it would have been impossible to develop isotopically distinct pools of uranium in ancient Earth environments. Conversely, an active U redox cycle leads to significant variability in δ238U values. Here we present a temporally and geographically expansive uranium isotope record from paleosols and modern soils to better constrain atmospheric oxygen levels during the Precambrian. Preliminary U isotope measurements of paleosols are unfractionated (relative to igneous rocks), possibly because of limited fractionation during oxidation (e.g., {Wang, 2015 #478}) or insufficient atmospheric oxygen levels to oxidize U(IV)-bearing minerals in the bedrock. Further U isotope measurements of paleosols with comparison to modern soils will resolve this issue.

  15. Heavy element stable isotope ratios: analytical approaches and applications.

    Science.gov (United States)

    Tanimizu, Masaharu; Sohrin, Yoshiki; Hirata, Takafumi

    2013-03-01

    Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-collector array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies.

  16. THE NITROGEN ISOTOPIC COMPOSITION OF METEORITIC HCN

    Energy Technology Data Exchange (ETDEWEB)

    Pizzarello, Sandra, E-mail: pizzar@asu.edu [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85018-1604 (United States)

    2014-12-01

    HCN is ubiquitous in extraterrestrial environments and is central to current theories on the origin of early solar system organic compounds such as amino acids. These compounds, observed in carbonaceous meteorites, were likely important in the origin and/or evolution of early life. As part of our attempts to understand the origin(s) of meteoritic CN{sup –}, we have analyzed the {sup 15}N/{sup 14}N isotopic composition of HCN gas released from water extracts of the Murchison meteorite and found its value to be near those of the terrestrial atmosphere. The findings, when evaluated viz-a-viz molecular abundances and isotopic data of meteoritic organic compounds, suggest that HCN formation could have occurred during the protracted water alteration processes known to have affected the mineralogy of many asteroidal bodies during their solar residence. This was an active synthetic stage, which likely involved simple gasses, organic molecules, their presolar precursors, as well as mineral catalysts and would have lead to the formation of molecules of differing isotopic composition, including some with solar values.

  17. Tracing Waste Water with Li isotopes

    Science.gov (United States)

    Millot, R.; Desaulty, A. M.

    2015-12-01

    The contribution of human activities such as industries, agriculture and various domestic inputs, becomes more and more significant in the chemical composition of the dissolved load of rivers. Human factors act as a supplementary key process. Therefore the mass-balance for the budget of catchments and river basins include anthropogenic disturbances. In the present study, we investigate waste water tracing by the use of Li isotopes in a small river basin near Orléans in France (l'Egoutier, 15 km² and 5 km long). It is well known that Li has strategic importance for numerous industrial applications including its use in the production of batteries for both mobile devices (computers, tablets, smartphones, etc.) and electric vehicles, but also in pharmaceutical formulations. In the present work, we collected river waters samples before and after the release from a waste water treatment plant connected to an hospital. Lithium isotopic compositions are rather homogeneous in river waters with δ7Li values around -0.5‰ ± 1 along the main course of the stream (n=7). The waste water sample is very different from the natural background of the river basin with Li concentration being twice of the values without pollution and significant heavy lithium contribution (δ7Li = +4‰). These preliminary results will be discussed in relation with factors controlling the distribution of Li and its isotopes in this specific system and compared with the release of other metals such as Pb or Zn.

  18. Apparatus and process for separating hydrogen isotopes

    Science.gov (United States)

    Heung, Leung K; Sessions, Henry T; Xiao, Xin

    2013-06-25

    The apparatus and process for separating hydrogen isotopes is provided using dual columns, each column having an opposite hydrogen isotopic effect such that when a hydrogen isotope mixture feedstock is cycled between the two respective columns, two different hydrogen isotopes are separated from the feedstock.

  19. Mass-dependent and -independent signature of Fe isotopes in magnetotactic bacteria.

    Science.gov (United States)

    Amor, Matthieu; Busigny, Vincent; Louvat, Pascale; Gélabert, Alexandre; Cartigny, Pierre; Durand-Dubief, Mickaël; Ona-Nguema, Georges; Alphandéry, Edouard; Chebbi, Imène; Guyot, François

    2016-05-06

    Magnetotactic bacteria perform biomineralization of intracellular magnetite (Fe3O4) nanoparticles. Although they may be among the earliest microorganisms capable of biomineralization on Earth, identifying their activity in ancient sedimentary rocks remains challenging because of the lack of a reliable biosignature. We determined Fe isotope fractionations by the magnetotactic bacterium Magnetospirillum magneticum AMB-1. The AMB-1 strain produced magnetite strongly depleted in heavy Fe isotopes, by 1.5 to 2.5 per mil relative to the initial growth medium. Moreover, we observed mass-independent isotope fractionations in (57)Fe during magnetite biomineralization but not in even Fe isotopes ((54)Fe, (56)Fe, and (58)Fe), highlighting a magnetic isotope effect. This Fe isotope anomaly provides a potential biosignature for the identification of magnetite produced by magnetotactic bacteria in the geological record.

  20. Quantification and isotope ratio determination of uranium in particles of environmental samples using isotope dilution thermal ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Choi, Eun-Ju [Chungnam National University, Daejeon (Korea, Republic of)

    2015-10-15

    Highly accurate and precise quantitative and qualitative analysis of nuclear materials in environmental samples plays essential roles in monitoring undeclared nuclear activities of corresponding facilities. The former focuses on the quantification of uranium (U) and plutonium (Pu) contained in a whole sample, while the latter enables us to acquire the isotopic ratios, which serve as the crucial basis to trace the nuclear histories of a facility. However, the quantity of nuclear materials in a single-particle has not been acquired from the particle analysis, but has been estimated by the size of the particles. This report is to describe the method developed to determine the quantity and the isotopic ratios of uranium in a micro-particle simultaneously. Complete dissolution of particle-spike mixture by repeated addition of nitric acid on a rhenium filament was performed to ensure the homogeneity of the mixture. Thermal ionization mass spectrometry (TIMS) was utilized to measure the U isotope ratios of the mixture with high accuracy. The isotopic ratios of the uranium in the particle sample were determined by mathematical deconvolution of U isotopic ratios of the mixture. Verification using particles of a certified reference material showed that the newly developed method can be used to quantify and to determine the isotopic ratios of U in a particle simultaneously. The development of a method for simultaneous determination of the quantity and the isotope ratios of uranium contained in particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS) was described. For homogeneity of the mixture of particles and spike, repeated dissolution using nitric acid for five times was performed.

  1. Alignments in the nobelium isotopes

    Institute of Scientific and Technical Information of China (English)

    ZHENG Shi-Zie; XU Fu-Rong; YUAN Cen-Xi; QI Chong

    2009-01-01

    Total-Routhian-Surface calculations have been performed to investigate the deformation and align-ment properties of the No isotopes. It is found that normal deformed and superdeformed states in these nuclei can coexist at low excitation energies. In neutron-deficient No isotopes, the superdeformed shapes can even become the ground states. Moreover, we plotted the kinematic moments of inertia of the No isotopes, which follow very nicely available experimental data. It is noted that, as the rotational frequency increases, align-ments develop at hω=0.2-0.3 MeV. Our calculations show that the occupation of the vj orbital plays an important role in the alignments of the No isotopes.

  2. Isotopic Changes During Digestion: Protein

    Science.gov (United States)

    Tuross, N.

    2013-12-01

    Nutrient and hydrological inputs traverse a complicated route of pH, enzymatic and cellular processes in digestion in higher animals. The end products of digestion are the starting products for biosynthesis that are often used to interpret past life-ways. Using an artificial gut system, the isotopic changes (dD, d18O, d13C and d15N) of protein are documented. Three separate protein sources are subjected to the conditions, chemical and enzymatic, found in the stomach and upper small intestine with only a small shift in the oxygen isotopic composition of the proteins observed. Middle to lower small intestine parameters produced both greater isotopic effects and significantly lower molecular weight products. The role of the gastric enterocyte and the likely involvement of the internal milieu of this cell in the isotopic composition of amino acids that are transported to the liver are reported.

  3. Isotope-based quantum information

    CERN Document Server

    G Plekhanov, Vladimir

    2012-01-01

    The present book provides to the main ideas and techniques of the rapid progressing field of quantum information and quantum computation using isotope - mixed materials. It starts with an introduction to the isotope physics and then describes of the isotope - based quantum information and quantum computation. The ability to manipulate and control electron and/or nucleus spin in semiconductor devices provides a new route to expand the capabilities of inorganic semiconductor-based electronics and to design innovative devices with potential application in quantum computing. One of the major challenges towards these objectives is to develop semiconductor-based systems and architectures in which the spatial distribution of spins and their properties can be controlled. For instance, to eliminate electron spin decoherence resulting from hyperfine interaction due to nuclear spin background, isotopically controlled devices are needed (i.e., nuclear spin-depleted). In other emerging concepts, the control of the spatial...

  4. Bioavailability of xenobiotics in unsaturated soils – implications for nucleic acid based stable isotope probing

    Science.gov (United States)

    The use of stable isotopes to label phylogenetically informative biomolecules (phospholipid fatty acids, DNA, or RNA), typically referred to as stable isotope probing (SIP) has the potential of providing definitive evidence that a detected population is active in a specific process, if that process ...

  5. The 226Ra isotope activities in ground water samples drawn of two wells from the Meridional Pluton, Morungaba Granitoids, eastern Sao Paulo State; Atividades do 226Ra em aguas subterraneas extraidas de dois pocos localizados no pluton meridional, granitoides de Morungaba, SP

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, Fabio de Oliveira; Silva Junior, Mario Goncalves da; Bertolla, Luciana; Ribeiro, Fernando Brenha [Sao Paulo Univ., SP (Brazil). Inst. de Astronomia, Geofisica e Ciencias Atmosfericas. Dept. de Geofisica]. E-mail: brenha@iag.usp.br

    2005-07-01

    The 226Ra activities, both in solution and associated with suspended solids, were measured in ground water samples drawn from two wells drilled in a fractured granitic aquifer from the Meridional Pluton, Morungaba Granitoids, eastern Sao Paulo State. The 226Ra isotope activities were measured in a sequence of samples collected about one month apart between March, 2003 and April 2004. The 226Ra activities were measured by radon gas emanometry. The mean dissolved 226Ra activity concentration activities observed in the two wells were (44.9 {+-} 7.1) mBq/L and (51.6 {+-} 8.8) mBq/L. The 226Ra activity of the suspend solids in a liter of these waters varied between (0,6 {+-} 0,1) mBq and (13 {+-} 1) mBq, respectively. (author)

  6. Paleoproxies: Heavy Stable Isotope Perspectives

    Science.gov (United States)

    Nagler, T. F.; Hippler, D.; Siebert, C.; Kramers, J. D.

    2002-12-01

    Recent advances in isotope ratio mass spectrometry, namely multiple collector ICP-MS and refined TIMS techniques, will significantly enhance the ability to measure heavy stable isotope fractionation, which will lead to the development of a wide array of process-identifying (bio)-geochemical tools. Thus far research in this area is not easily assessable to scientists outside the isotope field. This is due to the fact that analyzing heavy stable isotopes does not provide routine numbers which are per se true (the preciser the truer) but is still a highly experimental field. On the other hand resolving earth science problems requires specialists familiar with the environment being studied. So what is in there for paleoceanographers? In a first order approach, relating isotope variations to physical processes is straightforward. A prominent example are oxygen isotope variations with temperature. The total geological signal is of course far more complicated. At low temperatures, heavy stable isotopes variations have been reported for e.g. Ca, Cr, Fe, Cu, Zn, Mo and Tl. Fractionation mechanisms and physical parameters responsible for the observed variations are not yet resolved for most elements. Significant equilibrium isotope fractionation is expected from redox reactions of transition metals. However a difference in coordination number between two coexisting speciations of an element in the same oxidation state can also cause fractionation. Protonation of dissolved Mo is one case currently discussed. For paleoceanography studies, a principal distinction between transition metals essential for life (V to Zn plus Mo) or not will be helpful. In case of the former group, distinction between biogenic and abiogenic isotope fractionation will remain an important issue. For example, abiotic Fe redox reactions result in isotope fractionations indistinguishable in direction and magnitude from microbial effects. Only a combination of different stable isotope systems bears the

  7. NMR studies of isotopically labeled RNA

    Energy Technology Data Exchange (ETDEWEB)

    Pardi, A. [Univ. of Colorado, Boulder, CO (United States)

    1994-12-01

    In summary, the ability to generate NMR quantities of {sup 15}N and {sup 13}C-labeled RNAs has led to the development of heteronuclear multi-dimensional NMR techniques for simplifying the resonance assignment and structure determination of RNAs. These methods for synthesizing isotopically labeled RNAs are only several years old, and thus there are still relatively few applications of heteronuclear multi-dimensional NMR techniques to RNA. However, given the critical role that RNAs play in cellular function, one can expect to see an increasing number of NMR structural studies of biologically active RNAs.

  8. Isotope dilution gamma spectrometry for Pu using low energy photons

    Energy Technology Data Exchange (ETDEWEB)

    Paul, S.; Sarkar, A.; Alamelu, D.; Shah, R.V.; Aggarwal, S.K. [Bhabha Atomic Reseach Centre, Mumbai (India). Fuel Chemistry Div.

    2012-07-01

    Isotope dilution gamma spectrometry (IDGS) for determination of the Pu concentration, using high resolution gamma-ray spectrometry (HRGS) in the 40-150 keV energy range, is developed and described. The methodology involves purification of Pu by an anion exchange procedure, followed by the determination of Pu isotopic composition using HRGS. For isotope dilution, a pre-calibrated power reactor grade Pu ({proportional_to} 70 at. % {sup 239}Pu) solution from an Indian PHWR was used as a spike for research reactor grade Pu ({proportional_to} 95 at. % {sup 239}Pu) samples and vice versa. Changes in {sup 240}Pu/{sup 239}Pu (45.24 keV/51.62 keV) and {sup 241}Pu/{sup 239}Pu (148.57 keV/129.29 keV) activity ratios in the spiked samples were determined by gamma spectrometry. Using the atom ratios calculated from the measured activity ratios, the concentration of Pu in the sample was calculated using two different efficiency calibration methods. The isotopic composition and concentration of Pu samples both from power reactor and research reactor grade agreed well with the values obtained by isotope dilution-thermal ionization mass spectrometry. The present method also shows the superiority of using the {sup 240}Pu/{sup 239}Pu atom ratio against the {sup 241}Pu/{sup 239}Pu atom ratio in IDGS with respect to the accuracy and precision. (orig.)

  9. IUPAC Periodic Table of Isotopes for the Educational Community

    Energy Technology Data Exchange (ETDEWEB)

    Holden N. E.; Holden,N.E.; Coplen,T.B.

    2012-07-15

    John Dalton first proposed the concept of atomic weights of the elements in the first decade of the nineteenth century. These atomic weights of the chemical elements were thought of as constants of nature, similar to the speed of light. Dmitri Mendeleev arranged the atomic weights of the elements in ascending order of value and used the systematic variation of their chemical properties to produce his Periodic Table of the Elements in 1869. Measurement of atomic weight values became an important chemical activity for a century and a half. Theodore Richards received a Noble Prize for his work in this area. In 1913, Fredrick Soddy found a species of radium, which had an atomic weight value of 228, compared to the familiar radium gas value of 226. Soddy coined the term 'isotope' (Greek for 'in the same place') to account for this second atomic weight value in the radium position of the Periodic Table. Both of these isotopes of radium are radioactive. Radioactive isotopes are energetically unstable and will decay (disintegrate) over time. The time it takes for one half of a sample of a given radioactive isotope to decay is the half-life of that isotope. In addition to having different atomic weight values, radium-226 and radium-228 also have different half-life values. Around the same time as Soddy's work, J.J. Thomson (discoverer of the electron) identified two stable (non-radioactive) isotopes of the same element, neon. Over the next 40 years, the majority of the known chemical elements were found to have two or more stable (or long-lived radioactive isotopes that contribute significantly to the determination of the atomic weights of the elements).

  10. Degradation and Isotope Source Tracking of Glyphosate and Aminomethylphosphonic Acid.

    Science.gov (United States)

    Li, Hui; Joshi, Sunendra R; Jaisi, Deb P

    2016-01-27

    Glyphosate [N-(phosphonomethyl) glycine], an active ingredient of the herbicide Roundup, and its main metabolite, aminomethylphosphonic acid (AMPA), have been frequently reported to be present in soils and other environments and thus have heightened public concerns on their potential adverse effects. Understanding the fate of these compounds and differentiating them from other naturally occurring compounds require a toolbox of methods that can go beyond conventional methods. Here, we applied individual isotope labeling technique whereby each compound or mineral involved in the glyphosate and AMPA degradation reaction was either synthesized or chosen to have distinct (18)O/(16)O ratios so that the source of incorporated oxygen in the orthophosphate generated and corresponding isotope effect during C-P bond cleavage could be identified. Furthermore, we measured original isotope signatures of a few commercial glyphosate sources to identify their source-specific isotope signatures. Our degradation kinetics results showed that the rate of glyphosate degradation was higher than that of AMPA in all experimental conditions, and both the rate and extent of degradation were lowest under anoxic conditions. Oxygen isotope ratios (δ(18)OP) of orthophosphate generated from glyphosate and AMPA degradation suggested that one external oxygen atom from ambient water, not from dissolved oxygen or mineral, was incorporated into orthophosphate with the other three oxygen atoms inherited from the parent molecule. Interestingly, δ(18)OP values of all commercial glyphosate products studied were found to be the lightest among all orthophosphates known so far. Furthermore, isotope composition was found to be unaffected due to variable degradation kinetics, light/dark, and oxic/anoxic conditions. These results highlight the importance of phosphate oxygen isotope ratios as a nonconventional tool to potentially distinguish glyphosate sources and products from other organophosphorus compounds

  11. Isotope-committee reports 1999; Isotopkommitterapporter 1999

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, M.; McCarthy, G

    2000-12-01

    In this compilation the use of radioactive substances in therapies and in vivo examinations during 1999 is presented. For each examination the nuclide, chemical form, way of administration, number of hospitals, total number of examinations, mean activity used, interval of mean activity for the different hospitals and maximum activity is presented. Some examinations may be found at several different places. This is due to diverse routines of reporting and the confused use of old and new classifications. A certain caution is recommended when interpreting the data. Of the compilation it becomes known that during 1999 approximately 109,000 examinations and 2900 therapies were performed. The isotope committees at two hospitals have not presented their statistics.

  12. Isotopes a very short introduction

    CERN Document Server

    Ellam, Rob

    2016-01-01

    An isotope is a variant form of a chemical element, containing a different number of neutrons in its nucleus. Most elements exist as several isotopes. Many are stable while others are radioactive, and some may only exist fleetingly before decaying into other elements. In this Very Short Introduction, Rob Ellam explains how isotopes have proved enormously important across all the sciences and in archaeology. Radioactive isotopes may be familiar from their use in nuclear weapons, nuclear power, and in medicine, as well as in carbon dating. They have been central to establishing the age of the Earth and the origins of the solar system. Combining previous and new research, Ellam provides an overview of the nature of stable and radioactive isotopes, and considers their wide range of modern applications. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subjec...

  13. Exotic Structure of Carbon Isotopes

    CERN Document Server

    Suzuki, T; Hagino, K; Suzuki, Toshio; Sagawa, Hiroyuki; Hagino, Kouichi

    2002-01-01

    We studied firstly the ground state properties of C-isotopes using a deformed Hartree-Fock (HF)+ BCS model with Skyrme interactions. Shallow deformation minima are found in several neutron$-$rich C-isotopes. It is shown also that the deformation minima appear in both the oblate and the prolate sides in $^{17}$C and $^{19}$C having almost the same binding energies. Secondly, we carried out shell model calculations to study electromagnetic moments and electric dipole transitions of the C-isotopes. We point out the clear configuration dependence of the quadrupole and magnetic moments in the odd C-isotopes, which will be useful to find out the deformations and the spin-parities of the ground states of these nuclei. We studied electric dipole states of C-isotopes focusing on the interplay between low energy Pigmy strength and giant dipole resonances. Reasonable agreement is obtained with available experimental data for the photoreaction cross sections both in the low energy region below $\\hbar \\omega $=14 MeV and ...

  14. Handbook of environmental isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Baskaran, Mark (ed.) [Wayne State Univ., Detroit, MI (United States). Dept. Geology

    2011-07-01

    Applications of radioactive and stable isotopes have revolutionized our understanding of the Earth and near-earth surface processes. The utility of the isotopes are ever-increasing and our sole focus is to bring out the applications of these isotopes as tracers and chronometers to a wider audience so that they can be used as powerful tools to solve environmental problems. New developments in this field remain mostly in peer-reviewed journal articles and hence our goal is to synthesize these findings for easy reference for students, faculty, regulators in governmental and non-governmental agencies, and environmental companies. While this volume maintains its rigor in terms of its depth of knowledge and quantitative information, it contains the breadth needed for wide variety problems and applications in the environmental sciences. This volume presents all of the newer and older applications of isotopes pertaining to the environmental problems in one place that is readily accessible to readers. This book not only has the depth and rigor that is needed for academia, but it has the breadth and case studies to illustrate the utility of the isotopes in a wide variety of environments (atmosphere, oceans, lakes, rivers and streams, terrestrial environments, and sub-surface environments) and serves a large audience, from students and researchers, regulators in federal, state and local governments, and environmental companies. (orig.)

  15. Rate of radiocarbon retention onto calcite by isotope exchange

    Energy Technology Data Exchange (ETDEWEB)

    Lempinen, Janne; Lehto, Jukka [Helsinki Univ. (Finland). Lab. of Radiochemistry

    2016-11-01

    Radiocarbon ({sup 14}C) is a top priority class radionuclide associated with the long-term safety of spent nuclear fuel disposal. Dissolved inorganic radiocarbon can be retained in bedrock via isotope exchange with calcite (CaCO{sub 3}) at solubility equilibrium with groundwater. In the present study, the rate of the isotope exchange process was investigated on synthetic calcite using batch experiments. Experiments were performed in solutions with a calcium concentration of 0.0002-0.1 M, including two synthetic reference groundwaters. The radiocarbon activity in the solutions decreased exponentially as a function of time, thus following first-order kinetics. The rate of isotope exchange was quantified from an exponential fit to the activity data over time. The rate of radiocarbon retention increased as a function of the calcium activity. The isotope exchange half-life was only 4.3 days at calcium ion activities over 0.01. This half-life is very much shorter than the half-life of {sup 14}C or the time scale of groundwater movements; consequently calcite can effectively retain radiocarbon from brackish and saline groundwaters.

  16. Geochemical and isotopic characteristics of groundwater from Velenje Basin, Slovenia

    Science.gov (United States)

    Kanduč, Tjaša; Grassa, Fausto; Mori, Nataša; Verbovšek, Timotej

    2016-04-01

    The Velenje Basin in Slovenia is one of the largest actively mined coal basins in central Europe, producing around 4 million tons of lignite per year. Large amounts of groundwater are extracted from aquifers to facilitate underground mining of coal, and coal seam gas outbursts are a serious mine safety concern. This study analyses the geochemical and isotopic composition of groundwater to provide a general understanding of hydrogeological and geochemical processes in groundwater. Thirty-eight groundwater samples were taken from dewatering objects in the mine and at the surface in years 2014-2015. Groundwater in the Triassic aquifer is dominated by hydrogen carbonate, calcium, magnesium and isotopic composition of dissolved inorganic carbon in the range from -19.3 to -2.8‰ indicating degradation of soil organic matter and dissolution of carbonate minerals. In contrast, groundwater in the Pliocene aquifers is enriched in magnesium, sodium, calcium, potassium, and silicon, and has high alkalinity, with isotopic composition of dissolved inorganic carbon in the range of -14.4 to +4.6‰ . Based on isotopic composition of dissolved inorganic carbon values in all aquifers (Pliocene and Triassic), influencing processes are the dissolution of carbonate minerals and dissolution of organic matter, and additionally methanogenesis in the Pliocene aquifers. Based on the Principal Component Analysis (PCA) we can conclude that following different types of groundwater in Velenje Basin could be distinguished based on geochemical and isotopic data: Triassic aquifers with higher pH and lower conductivity and chloride, Pliocene, Pliocene 1 and Pliocene 2 aquifers with lower pH and higher conductivity and chloride contents, and Pliocene 3 and Pliocene 2, 3 aquifers with the highest pH and lowest conductivity and chloride contents. Major dissolved gas component in groundwater are carbon dioxide, nitrogen and methane. Concentrations of dissolved gases dewatering Triassic strata are low

  17. BOREAS TE-5 Tree Ring and Carbon Isotope Ratio Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected several data sets to investigate the vegetation-atmosphere CO2 and H2O exchange processes. These data include tree ring widths and cellulose carbon isotope data from coniferous trees collected at the BOREAS NSA and SSA in 1993 and 1994 by the BOREAS TE-5 team. Ring width data are provided for both Picea mariana and Pinus banksiana. The carbon isotope data are provided only for Pinus banksiana. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  18. Nitrogen isotopes in Tree-Rings - An approach combining soil biogeochemistry and isotopic long series with statistical modeling

    Science.gov (United States)

    Savard, Martine M.; Bégin, Christian; Paré, David; Marion, Joëlle; Laganière, Jérôme; Séguin, Armand; Stefani, Franck; Smirnoff, Anna

    2016-04-01

    Monitoring atmospheric emissions from industrial centers in North America generally started less than 25 years ago. To compensate for the lack of monitoring, previous investigations have interpreted tree-ring N changes using the known chronology of human activities, without facing the challenge of separating climatic effects from potential anthropogenic impacts. Here we document such an attempt conducted in the oil sands (OS) mining region of Northeastern Alberta, Canada. The reactive nitrogen (Nr)-emitting oil extraction operations began in 1967, but air quality measurements were only initiated in 1997. To investigate if the beginning and intensification of OS operations induced changes in the forest N-cycle, we sampled white spruce (Picea glauca (Moench) Voss) stands located at various distances from the main mining area, and receiving low, but different N deposition. Our approach combines soil biogeochemical and metagenomic characterization with long, well dated, tree-ring isotopic series. To objectively delineate the natural N isotopic behaviour in trees, we have characterized tree-ring N isotope (15N/14N) ratios between 1880 and 2009, used statistical analyses of the isotopic values and local climatic parameters of the pre-mining period to calibrate response functions and project the isotopic responses to climate during the extraction period. During that period, the measured series depart negatively from the projected natural trends. In addition, these long-term negative isotopic trends are better reproduced by multiple-regression models combining climatic parameters with the proxy for regional mining Nr emissions. These negative isotopic trends point towards changes in the forest soil biogeochemical N cycle. The biogeochemical data and ultimate soil mechanisms responsible for such changes will be discussed during the presentation.

  19. Hydrogen isotope separation for fusion power applications

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R., E-mail: robert.smith@ccfe.ac.uk [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Whittaker, D.A.J.; Butler, B.; Hollingsworth, A.; Lawless, R.E.; Lefebvre, X.; Medley, S.A.; Parracho, A.I.; Wakeling, B. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2015-10-05

    Highlights: • Summary of the tritium plant, the Active Gas Handling System (AGHS), at JET. • Review of the Water Detritiation System (WDS) under construction. • Design of the new Material Detritiation Facility (MDF). • Review of problems in fusion related to metal/hydrogen system. - Abstract: The invited talk given at MH2014 in Salford ranged over many issues associated with hydrogen isotope separation, fusion machines and the hydrogen/metal systems found in the Joint European Torus (JET) machine located near Oxford. As this sort of talk does not lend itself well to a paper below I have attempted to highlight some of the more pertinent information. After a description of the Active Gas Handling System (AGHS) a brief summary of isotope separation systems is described followed by descriptions of three major projects currently being undertaken by the Tritium Engineering and Science Group (TESG), the upgrade to the Analytical Systems (AN-GC) at the AGH, the construction of a Water Detritiation System (WDS) and a Material Detritiation Facility (MDF). Finally, a review of some of the challenges facing fusion with respect to metal/hydrogen systems is presented.

  20. Medical Isotope Production Analyses In KIPT Neutron Source Facility

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Argonne National Lab. (ANL), Argonne, IL (United States); Gohar, Yousry [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    Medical isotope production analyses in Kharkov Institute of Physics and Technology (KIPT) neutron source facility were performed to include the details of the irradiation cassette and the self-shielding effect. An updated detailed model of the facility was used for the analyses. The facility consists of an accelerator-driven system (ADS), which has a subcritical assembly using low-enriched uranium fuel elements with a beryllium-graphite reflector. The beryllium assemblies of the reflector have the same outer geometry as the fuel elements, which permits loading the subcritical assembly with different number of fuel elements without impacting the reflector performance. The subcritical assembly is driven by an external neutron source generated from the interaction of 100-kW electron beam with a tungsten target. The facility construction was completed at the end of 2015, and it is planned to start the operation during the year of 2016. It is the first ADS in the world, which has a coolant system for removing the generated fission power. Argonne National Laboratory has developed the design concept and performed extensive design analyses for the facility including its utilization for the production of different radioactive medical isotopes. 99Mo is the parent isotope of 99mTc, which is the most commonly used medical radioactive isotope. Detailed analyses were performed to define the optimal sample irradiation location and the generated activity, for several radioactive medical isotopes, as a function of the irradiation time.

  1. The terrestrial uranium isotope cycle.

    Science.gov (United States)

    Andersen, Morten B; Elliott, Tim; Freymuth, Heye; Sims, Kenneth W W; Niu, Yaoling; Kelley, Katherine A

    2015-01-15

    Changing conditions on the Earth's surface can have a remarkable influence on the composition of its overwhelmingly more massive interior. The global distribution of uranium is a notable example. In early Earth history, the continental crust was enriched in uranium. Yet after the initial rise in atmospheric oxygen, about 2.4 billion years ago, the aqueous mobility of oxidized uranium resulted in its significant transport to the oceans and, ultimately, by means of subduction, back to the mantle. Here we explore the isotopic characteristics of this global uranium cycle. We show that the subducted flux of uranium is isotopically distinct, with high (238)U/(235)U ratios, as a result of alteration processes at the bottom of an oxic ocean. We also find that mid-ocean-ridge basalts (MORBs) have (238)U/(235)U ratios higher than does the bulk Earth, confirming the widespread pollution of the upper mantle with this recycled uranium. Although many ocean island basalts (OIBs) are argued to contain a recycled component, their uranium isotopic compositions do not differ from those of the bulk Earth. Because subducted uranium was probably isotopically unfractionated before full oceanic oxidation, about 600 million years ago, this observation reflects the greater antiquity of OIB sources. Elemental and isotope systematics of uranium in OIBs are strikingly consistent with previous OIB lead model ages, indicating that these mantle reservoirs formed between 2.4 and 1.8 billion years ago. In contrast, the uranium isotopic composition of MORB requires the convective stirring of recycled uranium throughout the upper mantle within the past 600 million years.

  2. Atmospheric circulation controls on the inter-annual variability in precipitation isotope ratio in Japan

    Directory of Open Access Journals (Sweden)

    N. Kurita

    2014-10-01

    Full Text Available This study explored the primary driver of variations of precipitation isotopes at multiple temporal scales (event, seasonal and inter-annual scales to provide a greater depth of interpretation for isotope proxy records in Japan. A one-year record of the isotopic composition of event-based precipitation at Nagoya in central Japan showed less seasonal variation, but there is large isotopic variability on a storm-to-storm basis. In the summer, southerly flows transport isotopically enriched moisture from subtropical marine regions with the result that the rainfall produced by the subtropical air, or warm rainfall, was relatively enriched in heavy isotopes in comparison with the other rainfall events. In the winter, storm tracks are the dominant driver of storm-to-storm isotopic variation, and relatively lower isotopic values occurred when northerly winds in association with extratropical cyclones passing off the south coast of Japan (Nangan cyclone brings cold precipitation. Using the historical 17 year record of monthly isotopes in precipitation at Tokyo station, we explored if the factors controlling event-scale isotopic variability can account for inter-annual isotopic variability. The relatively higher isotopes in summer precipitation were attributed to the higher contribution of the warm rainfall to the total summer precipitation. On the other hand, year-to-year variation of isotopic values in winter precipitation was negatively correlated with the relative ratio of the Nangan cyclone rainfall to the total winter precipitation. The 17 year precipitation history demonstrates that event-scale isotopic variability related to changes in meridional moisture transport is the primary driver of inter-annual isotopic variability in winter and summer precipitation. The meridional moisture transport to central Japan is likely linked to the activity of the western North Pacific subtropical high in summer and the intensity of the East Asian winter monsoon

  3. Non-linear Isotope Effects

    DEFF Research Database (Denmark)

    Schmidt, Johan Albrecht

    The isotopic fractionation associated with photodissociation of N2O, OCS and CO2, at different altitudes in Earth’s atmosphere, is investigated theoretically using constructed quantum mechanical models of the dissociation processes (i.e. potential energy surfaces and relevant coupling elements...... or moderate, and overall sulfur fractionation in the stratosphere is very weak which does not exclude OCS from being an acceptable background the Stratospheric Sulfate Aerosol layer. (iii) CO2 photolysis in the upper stratosphere and lower mesosphere is highly fractionating in both isotopes, enriching...

  4. Plutonium isotopes in the atmosphere of Central Europe: Isotopic composition and time evolution vs. circulation factors.

    Science.gov (United States)

    Kierepko, Renata; Mietelski, Jerzy W; Ustrnul, Zbigniew; Anczkiewicz, Robert; Wershofen, Herbert; Holgye, Zoltan; Kapała, Jacek; Isajenko, Krzysztof

    2016-11-01

    This paper reports evidence of Pu isotopes in the lower part of the troposphere of Central Europe. The data were obtained based on atmospheric aerosol fraction samples collected from four places in three countries (participating in the informal European network known as the Ring of Five (Ro5)) forming a cell with a surface area of about 200,000km(2). We compared our original data sets from Krakow (Poland, 1990-2007) and Bialystok (Poland, 1991-2007) with the results from two other locations, Prague (Czech Republic; 1997-2004) and Braunschweig (Germany; 1990-2003) to find time evolution of the Pu isotopes. The levels of the activity concentration for (238)Pu and for ((239+240))Pu were estimated to be a few and some tens of nBqm(-3), respectively. However, we also noted some results were much higher (even about 70 times higher) than the average concentration of (238)Pu in the atmosphere. The achieved complex data sets were used to test a new approach to the problem of solving mixing isotopic traces from various sources (here up to three) in one sample. Results of our model, supported by mesoscale atmospheric circulation parameters, suggest that Pu from nuclear weapon accidents or tests and nuclear burnt-up fuel are present in the air.

  5. Do Speleothem Stable Isotope Records Contain Hidden Tropical Cyclone Histories? Exploring C-O Isotope Correlation Patterns for Indicators of Tropical Cyclone Masking

    Science.gov (United States)

    Frappier, A. E.; Rossington, C.

    2013-12-01

    The newly-described tropical cyclone masking effect on stable isotope paleohydrological signals in speleothem records arises from the intermittent delivery of large pulses of isotopically distinct tropical cyclone rain. Recent work shows that 18-O depleted tropical cyclone stormwater depresses the δ18O value of speleothem calcite for months to years following a tropical cyclone event, masking the background stable isotope signal of persistent climate variability. Periods of high local storm activity can lead to speleothem calcite paleohydrological signals with significant wet biases on interannual to decadal timescales. Because speleothem carbon isotope ratios are independent of tropical cyclone rainfall, tropical speleothems are known to exhibit moderate C-O isotope covariation over time, periods when C-O isotope covariation breaks down and δ18O values are low may provide a marker for times when tropical cyclone masking is important. If so, existing speleothem stable isotope records from tropical cyclone-prone regions may contain signatures of tropical cyclone masking in the temporal evolution of C-O isotope covariation patterns. We present results from an exploratory analysis of several published speleothem records that are candidates for containing tropical cyclone masking signals. For each speleothem, overall C-O isotope covariation coefficients were calculated, and transient covariation patterns were analyzed using a sliding correlation index, the Covariation of Stable Isotopes (CoSI) index, and Local Correlation (LoCo). Local tropical cyclone historical and paleotempest records are compared and a method is presented to test for the presence of tropical cyclone masking intervals. The implications for speleothem paleoclimatology and paleotempestology are discussed.

  6. The separation of stable isotopes of carbon

    Science.gov (United States)

    Oziashvili, E. D.; Egiazarov, A. S.

    1989-04-01

    The present state of work on the separation of carbon isotopes by diffusion, fractional distillation, chemical isotopic exchange, and the selective excitation and dissociation of molecules in electrical discharges or in the field of laser radiation has been examined. The characteristics of new laboratory and industrial assemblies for separating carbon isotopes have been described. Promising directions of study aimed at developing effective technological processes for separating carbon isotopes have been noted. The bibliography contains 148 references.

  7. Brief review on the development of isotope hydrology in China

    Institute of Scientific and Technical Information of China (English)

    汪集旸; 孙占学

    2001-01-01

    The development of isotope hydrology in China is briefly reviewed. It includes oxygen and hydrogen isotopes of precipitation, application of isotope hydrological methodologies in solving water resources problems, isotope hydrological studies on brines and salt lake waters, as well as isotope hydrological investigations of thermal waters. The review focuses on isotope hydrology in China during the last two decades.

  8. Substitution of stable isotopes in Chlorella

    Science.gov (United States)

    Flaumenhaft, E.; Katz, J. J.; Uphaus, R. A.

    1969-01-01

    Replacement of biologically important isotopes in the alga Chlorella by corresponding heavier stable isotopes produces increasingly greater deviations from the normal cell size and changes the quality and distribution of certain cellular components. The usefulness of isotopically altered organisms increases interest in the study of such permuted organisms.

  9. Dry phase reactor for generating medical isotopes

    Science.gov (United States)

    Mackie, Thomas Rockwell; Heltemes, Thad Alexander

    2016-05-03

    An apparatus for generating medical isotopes provides for the irradiation of dry-phase, granular uranium compounds which are then dissolved in a solvent for separation of the medical isotope from the irradiated compound. Once the medical isotope is removed, the dissolved compound may be reconstituted in dry granular form for repeated irradiation.

  10. High-resolution (SIMS) versus bulk sulfur isotope patterns of pyrite in Proterozoic microbialites with diverse mat textures

    Science.gov (United States)

    Gomes, M. L.; Fike, D. A.; Bergmann, K.; Knoll, A. H.

    2015-12-01

    Sulfur (S) isotope signatures of sedimentary pyrite preserved in marine rocks provide a rich suite of information about changes in biogeochemical cycling associated with the evolution of microbial metabolisms and oxygenation of Earth surface environments. Conventionally, these S isotope records are based on bulk rock measurements. Yet, in modern microbial mat environments, S isotope compositions of sulfide can vary by up to 40‰ over a spatial range of ~ 1 mm. Similar ranges of S isotope variability have been found in Archean pyrite grains using both Secondary Ion Mass Spectrometry and other micro-analytical techniques. These micron-scale patterns have been linked to changes in rates of microbial sulfate reduction and/or sulfide oxidation, isotopic distillation of the sulfate reservoir due to microbial sulfate reduction, and post-depositional alteration. Fine-scale mapping of S isotope compositions of pyrite can thus be used to differentiate primary environmental signals from post-depositional overprinting - improving our understanding of both. Here, we examine micron-scale S isotope patterns of pyrite in microbialites from the Mesoproterozoic-Neoproterozoic Sukhaya Tunguska Formation and Neoproterozoic Draken Formation in order to explore S isotope variability associated with different mat textures and pyrite grain morphologies. A primary goal is to link modern observations of how sulfide spatial isotope distributions reflect active microbial communities present at given depths in the mats to ancient processes driving fine-sale pyrite variability in microbialites. We find large (up to 60‰) S isotope variability within a spatial range of less than 2.5cm. The micron-scale S isotope measurements converge around the S isotope composition of pyrite extracted from bulk samples of the same microbialites. These micron-scale pyrite S isotope patterns have the potential to reveal important information about ancient biogeochemical cycling in Proterozoic mat environments

  11. Bayesian stable isotope mixing models

    Science.gov (United States)

    In this paper we review recent advances in Stable Isotope Mixing Models (SIMMs) and place them into an over-arching Bayesian statistical framework which allows for several useful extensions. SIMMs are used to quantify the proportional contributions of various sources to a mixtur...

  12. Research Progress of Isotope Technology

    Institute of Scientific and Technical Information of China (English)

    Department; of; Isotope

    2015-01-01

    Radioactive isotope is one of the origins of nonnuclear power technology.In the 12th Five Year Plan period,CIAE made breakthrough progresses on several important fields such as research and development of preparation of radioactive nuclides,preparation of radioactive source and study of radiopharmaceuticals relied on different financial support,successfully

  13. Operation of Electromagnetic Isotope Separator

    Institute of Scientific and Technical Information of China (English)

    MI; Ya-jing

    2015-01-01

    In 2015,we mainly completed the installation of the electromagnetic isotope separator comprehensive technical transformation projects,including the work of installation,debugging,commissioning and acceptance.In June 30,2015,according to the schedule requirements,the project

  14. Isotope Harvesting Opportunities at FRIB

    Science.gov (United States)

    Morrissey, David

    2017-01-01

    The fragmentation of fast heavy ion beams now at the National Superconducting Cyclotron Laboratory (NSCL) and in the future at the Facility for Rare Isotope Beams (FRIB) under construction produce an unprecedentedly broad spectrum of radionuclides but only a small fraction are used in the on-line rare-isotope program. Projectile fragmentation facilities provide an electromagnetically purified beam of a single projectile fragment for nuclear physics experiments ranging from low energy astrophysics, through nuclear structure studies, to probing fundamental symmetries. By augmenting the NSCL and FRIB production facilities with complimentary collection and purification of discarded ions, called isotope harvesting with chemical purification, many other nuclides will become available for off-line experiments in parallel with the primary experiment. A growing user community has established a list of key target isotopes and is working with the FRIB design team to allow inclusion of necessary equipment in the future. An overview of the possibilities and the techniques will be presented in this talk. Supported by Office of Science, US DOE and Michigan State University.

  15. The Behaviour of Chromium Isotopes during the Oxidative Weathering of Ultramafic Rocks

    DEFF Research Database (Denmark)

    Paulukat, Cora Stefanie; Døssing, Lasse Nørbye; Mondal, Sisir K.;

    Ore Group in the southern Singhbhum Craton (Orissa, India)[3]. A modern weathering profile was logged in an active open cast chromite mine (Sukinda valley). The Cr isotope data of samples from the weathering profile are fractionaed. While the least weathered horizons at the base of the profile reflect......The chromium isotope system has been proven to be a redox-sensitve proxy in ancient and modern environmental studies (e.g. [1], [2]). In this study we investigated Cr isotope fractionation during soil formation from Archean (3.1-3.3 Ga) ultramafic rocks, intruded into metamorphic rocks of the Iron...... are characterised by a Cr loss of up to 74 %. These data are consistent with the findings of Crowe et al. [2] who also studied the effects of weathering of ultramafic rocks in Indonesia on the Cr isotope system. These authors demonstrate that oxidation of Cr(III) to Cr(VI) in the soils is accompanied by isotopic...

  16. Stable isotopes of transition and post-transition metals as tracers in environmental studies

    Science.gov (United States)

    Bullen, Tomas D.; Baskaran, Mark

    2011-01-01

    The transition and post-transition metals, which include the elements in Groups 3–12 of the Periodic Table, have a broad range of geological and biological roles as well as industrial applications and thus are widespread in the environment. Interdisciplinary research over the past decade has resulted in a broad understanding of the isotope systematics of this important group of elements and revealed largely unexpected variability in isotope composition for natural materials. Significant kinetic and equilibrium isotope fractionation has been observed for redox sensitive metals such as iron, chromium, copper, molybdenum and mercury, and for metals that are not redox sensitive in nature such as cadmium and zinc. In the environmental sciences, the isotopes are increasingly being used to understand important issues such as tracing of metal contaminant sources and fates, unraveling metal redox cycles, deciphering metal nutrient pathways and cycles, and developing isotope biosignatures that can indicate the role of biological activity in ancient and modern planetary systems.

  17. Calcium isotope analysis by mass spectrometry.

    Science.gov (United States)

    Boulyga, Sergei F

    2010-01-01

    The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo- and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low-abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075-1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. The present article discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. In Sections 2 and 3, mass spectrometric methods applied to precise stable isotope analysis and to the determination of (41)Ca are described. Section 4 contains a short summary of selected applications, and includes tracer experiments and the potential use

  18. A global Ge isotope budget

    Science.gov (United States)

    Baronas, J. Jotautas; Hammond, Douglas E.; McManus, James; Wheat, C. Geoffrey; Siebert, Christopher

    2017-04-01

    We present measurements of Ge isotope composition and ancillary data for samples of river water, low- and high-temperature hydrothermal fluids, and seawater. The dissolved δ74Ge composition of analyzed rivers ranges from 2.0 to 5.6‰, which is significantly heavier than previously determined values for silicate rocks (δ74Ge = 0.4-0.7‰, Escoube et al., Geostand. Geoanal. Res., 36(2), 2012) from which dissolved Ge is primarily derived. An observed negative correlation between riverine Ge/Si and δ74Ge signatures suggests that the primary δ74Ge fractionation mechanism during rock weathering is the preferential incorporation of light isotopes into secondary weathering products. High temperature (>150 °C) hydrothermal fluids analyzed in this study have δ74Ge of 0.7-1.6‰, most likely fractionated during fluid equilibration with quartz in the reaction zone. Low temperature (25-63 °C) hydrothermal fluids are heavier (δ74Ge between 2.9‰ and 4.1‰) and most likely fractionated during Ge precipitation with hydrothermal clays. Seawater from the open ocean has a δ74Gesw value of 3.2 ± 0.4‰, and is indistinguishable among the different ocean basins at the current level of precision. This value should be regulated over time by the isotopic balance of Ge sources and sinks, and a new compilation of these fluxes is presented, along with their estimated isotopic compositions. Assuming steady-state, non-opal Ge sequestration during sediment authigenesis likely involves isotopic fractionation Δ74Gesolid-solution that is -0.6 ± 1.8‰.

  19. Modelling stable water isotopes: Status and perspectives

    Directory of Open Access Journals (Sweden)

    Werner M.

    2010-12-01

    Full Text Available Modelling of stable water isotopes H2 18O and HDO within various parts of the Earth’s hydrological cycle has clearly improved our understanding of the interplay between climatic variations and related isotope fractionation processes. In this article key principles and major research results of stable water isotope modelling studies are described. Emphasis is put on research work using explicit isotope diagnostics within general circulation models as this highly complex model setup bears many resemblances with studies using simpler isotope modelling approaches.

  20. Stable Isotope Measurements of Carbon Dioxide, Methane, and Hydrogen Sulfide Gas Using Frequency Modulation Spectroscopy

    Science.gov (United States)

    Nowak-Lovato, K.

    2014-12-01

    Seepage from enhanced oil recovery, carbon storage, and natural gas sites can emit trace gases such as carbon dioxide, methane, and hydrogen sulfide. Trace gas emission at these locations demonstrate unique light stable isotope signatures that provide information to enable source identification of the material. Light stable isotope detection through surface monitoring, offers the ability to distinguish between trace gases emitted from sources such as, biological (fertilizers and wastes), mineral (coal or seams), or liquid organic systems (oil and gas reservoirs). To make light stable isotope measurements, we employ the ultra-sensitive technique, frequency modulation spectroscopy (FMS). FMS is an absorption technique with sensitivity enhancements approximately 100-1000x more than standard absorption spectroscopy with the advantage of providing stable isotope signature information. We have developed an integrated in situ (point source) system that measures carbon dioxide, methane and hydrogen sulfide with isotopic resolution and enhanced sensitivity. The in situ instrument involves the continuous collection of air and records the stable isotope ratio for the gas being detected. We have included in-line flask collection points to obtain gas samples for validation of isotopic concentrations using our in-house isotope ratio mass spectroscopy (IRMS). We present calibration curves for each species addressed above to demonstrate the sensitivity and accuracy of the system. We also show field deployment data demonstrating the capabilities of the system in making live dynamic measurements from an active source.

  1. Heterogeneous distribution of Zn stable isotopes in mice and applications to medical sciences

    Science.gov (United States)

    Moynier, F.; Fujii, T.; Shaw, A.; Le Borgne, M.

    2013-12-01

    Zinc is required for the function of more than 300 enzymes involved in many metabolic pathways, and is a vital micronutrient for living organisms. To investigate if Zn isotopes could be used to better understand metal homeostasis, as well as a biomarker for diseases, we assessed the distribution of natural Zn isotopes in various mouse tissues. We found that, with respect to Zn isotopes, most mouse organs are isotopically distinct and that the total range of variation within one mouse encompasses the variations observed in the Earth's crust. Therefore, biological activity must have a major impact on the distribution of Zn isotopes in inorganic materials. The most striking aspect of the data is that red blood cells and bones are enriched by ~0.5 per mil in 66Zn relative to 64Zn when compared to serum, and up to ~1 per mil when compared to the brain and liver. This fractionation is well explained by the equilibrium distribution of isotopes between different bonding environments of Zn in different organs. Differences in gender and genetic background did not appear to affect the isotopic distribution of Zn. Together, these results suggest that potential use of Zn isotopes as a tracer for dietary Zn, and for detecting disturbances in Zn metabolism due to pathological conditions.

  2. Heavy atom isotope effects on enzymatic reactions

    Science.gov (United States)

    Paneth, Piotr

    1994-05-01

    The theory of isotope effects, which has proved to be extremely useful in providing geometrical details of transition states in a variety of chemical reactions, has recently found an application in studies of enzyme-catalyzed reactions. These reactions are multistep in nature with few steps being partially rate-limiting, thus interpretation of these isotope effects is more complex. The theoretical framework of heavy-atom isotope effects on enzymatic reactions is critically analyzed on the basis of recent results of: carbon kinetic isotope effects on carbonic anhydrase and catalytic antibodies; multiple carbon, deuterium isotope effects on reactions catalyzed by formate decarboxylase; oxygen isotope effects on binding processes in reactions catalyzed by pyruvate kinase; and equilibrium oxygen isotope effect on binding an inhibitor to lactate dehydrogenase. The advantages and disadvantages of reaction complexity in learning details of formal and molecular mechanisms are discussed in the examples of reactions catalyzed by phosphoenolpyruvate carboxylase, orotidine decarboxylase and glutamine synthetase.

  3. Zinc isotopic compositions of breast cancer tissue.

    Science.gov (United States)

    Larner, Fiona; Woodley, Laura N; Shousha, Sami; Moyes, Ashley; Humphreys-Williams, Emma; Strekopytov, Stanislav; Halliday, Alex N; Rehkämper, Mark; Coombes, R Charles

    2015-01-01

    An early diagnostic biomarker for breast cancer is essential to improve outcome. High precision isotopic analysis, originating in Earth sciences, can detect very small shifts in metal pathways. For the first time, the natural intrinsic Zn isotopic compositions of various tissues in breast cancer patients and controls were determined. Breast cancer tumours were found to have a significantly lighter Zn isotopic composition than the blood, serum and healthy breast tissue in both groups. The Zn isotopic lightness in tumours suggests that sulphur rich metallothionein dominates the isotopic selectivity of a breast tissue cell, rather than Zn-specific proteins. This reveals a possible mechanism of Zn delivery to Zn-sequestering vesicles by metallothionein, and is supported by a similar signature observed in the copper isotopic compositions of one breast cancer patient. This change in intrinsic isotopic compositions due to cancer has the potential to provide a novel early biomarker for breast cancer.

  4. Measuring SNM Isotopic Distributions using FRAM

    Energy Technology Data Exchange (ETDEWEB)

    Geist, William H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-02

    The first group of slides provides background information on the isotopic composition of plutonium. It is shown that 240Pu is the critical isotope in neutron coincidence/multiplicity counting. Next, response function analysis to determine isotopic composition is discussed. The isotopic composition can be determined by measuring the net peak counts from each isotope and then taking the ratio of the counts for each isotope relative to the total counts for the element. Then FRAM (Fixed energy Response function Analysis with Multiple efficiencies) is explained. FRAM can control data acquisition, automatically analyze newly acquired data, analyze previously acquired data, provide information on the quality of the analysis, and facilitate analysis in unusual situations (non-standard energy calibrations, gamma rays from non-SNM isotopes, poor spectra (within limits)).

  5. Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems

    Energy Technology Data Exchange (ETDEWEB)

    Nimz, G. J., LLNL

    1998-06-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water. Many solutes in natural waters are derived from the interaction between the water and the rock and/or soil within the system - these are termed `lithogenic` solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both within and outside of the catchment - i.e., in addition to being derived from catchment rock and soil, they are solutes that are also transported into the catchment. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing `cosmogenic` nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing `thermonuclear` nuclides), or radioactive and fission decay of naturally-occurring elements, principally {sup 238}U (producing `in-situ` lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading `cosmogenic nuclides`, and for simplicity we will often follow that usage here, although always indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute concentrations in catchment waters, and how the isotopic compositions of the solutes can be used in integrative ways to identify these processes, thereby revealing the physical history of the water within a catchment system. The concept of a `system` is important in catchment hydrology. A catchment is the smallest landscape unit that can both participate in all of the aspects of the hydrologic cycle and

  6. Effective technique for numerical kinetics calculations in a system of anharmonic oscillators. Application to study of the influence of the isotopic composition of molecules on the properties of a carbon monoxide active medium

    Energy Technology Data Exchange (ETDEWEB)

    Bunkin, S.B.; Islamov, R.S.; Konev, Y.B.; Kochetov, I.V.

    1982-07-01

    A technique is described for numerical analysis of kinetic processes in a system of anharmonic oscillators, based on using implicit numerical integration and replacement of derivatives by means of backward differentiation expressions. A comparison is made with calculations by the Runge--Kutta method, and it is shown that the computer time is reduced by a factor of more than 10 when the backward differentiation method is used. The influence of the natural isotopic composition of carbon monoxide molecules on the gain and lasing properties is investigated and shown to be only slight.

  7. High-resolution quadruple sulfur isotope analyses of 3.2 Ga pyrite from the Barberton Greenstone Belt in South Africa reveal distinct environmental controls on sulfide isotopic arrays

    NARCIS (Netherlands)

    Roerdink, D.L.; Mason, P.R.D.; Whitehouse, M.J.; Reimer, T.

    2013-01-01

    Multiple sulfur isotopes in Paleoarchean pyrite record valuable information on atmospheric processes and emerging microbial activity in the early sulfur cycle. Here, we report quadruple sulfur isotope data (32S, 33S, 34S, 36S) analyzed by secondary ion mass spectrometry from pyrite in a 3.26–3.23 Ga

  8. Production of medical radioactive isotopes using KIPT electron driven subcritical facility

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Nuclear Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)], E-mail: alby@anl.gov; Gohar, Yousry [Nuclear Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2008-05-15

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine in collaboration with Argonne National Laboratory (ANL) has a plan to construct an electron accelerator driven subcritical assembly. One of the facility objectives is the production of medical radioactive isotopes. This paper presents the ANL collaborative work performed for characterizing the facility performance for producing medical radioactive isotopes. First, a preliminary assessment was performed without including the self-shielding effect of the irradiated samples. Then, more detailed investigation was carried out including the self-shielding effect, which defined the sample size and location for producing each medical isotope. In the first part, the reaction rates were calculated as the multiplication of the cross section with the unperturbed neutron flux of the facility. Over fifty isotopes have been considered and all transmutation channels are used including (n, {gamma}), (n, 2n), (n, p), and ({gamma}, n). In the second part, the parent isotopes with high reaction rate were explicitly modeled in the calculations. Four irradiation locations were considered in the analyses to study the medical isotope production rate. The results show the self-shielding effect not only reduces the specific activity but it also changes the irradiation location that maximizes the specific activity. The axial and radial distributions of the parent capture rates have been examined to define the irradiation sample size of each parent isotope.

  9. Interstellar Isotopes: Prospects with ALMA

    Science.gov (United States)

    Charnley Steven B.

    2010-01-01

    Cold molecular clouds are natural environments for the enrichment of interstellar molecules in the heavy isotopes of H, C, N and O. Anomalously fractionated isotopic material is found in many primitive Solar System objects, such as meteorites and comets, that may trace interstellar matter that was incorporated into the Solar Nebula without undergoing significant processing. Models of the fractionation chemistry of H, C, N and O in dense molecular clouds, particularly in cores where substantial freeze-out of molecules on to dust has occurred, make several predictions that can be tested in the near future by molecular line observations. The range of fractionation ratios expected in different interstellar molecules will be discussed and the capabilities of ALMA for testing these models (e.g. in observing doubly-substituted isotopologues) will be outlined.

  10. Natural fractionation of uranium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Noordmann, Janine

    2015-01-24

    The topic of this thesis was the investigation of U (n({sup 238}U) / n({sup 235}U)) isotope variations in nature with a focus on samples (1) that represent the continental crust and its weathering products (i.e. granites, shales and river water) (2) that represent products of hydrothermal alteration on mid-ocean ridges (i.e. altered basalts, carbonate veins and hydrothermal water) and (3) from restricted euxinic basins (i.e. from the water column and respective sediments). The overall goal was to explore the environmental conditions and unravel the mechanisms that fractionate the two most abundant U isotopes, n({sup 238}U) and n({sup 235}U), on Earth.

  11. Variations in the chemical and stable isotope composition of carbon and sulfur species during organic-rich sediment alteration: An experimental and theoretical study of hydrothermal activity at guaymas basin, gulf of california

    Science.gov (United States)

    Seewald, Jeffrey S.; Seyfried, William E., Jr.; Shanks, Wayne C., III

    1994-11-01

    Organic-rich diatomaceous ooze was reacted with seawater and a Na-Ca-K-Cl fluid of seawater chlorinity at 325-400°C, 400-500 bars, and fluid/sediment mass ratios of 1.56-2.35 to constrain factors regulating the abundance and stable isotope composition of C and S species during hydrothermal alteration of sediment from Guaymas Basin, Gulf of California. Alteration of inorganic and organic sedimentary components resulted in extensive exchange reactions, the release of abundant H 2S, CO 2, CH 4, and C organic, to solution, and recrystallization of the sediment to an assemblage containing albitic plagioclase, quartz, pyrrhotite, and calcite. The δ 34S cdt values of dissolved H 2S varied from -10.9 to +4.3‰ during seawater-sediment interaction at 325 and 400°C and from -16.5 to -9.0‰ during Na-Ca-K-Cl fluid-sediment interaction at 325 and 375°C. In the absence of seawater SO 4, H 2S is derived from both the transformation of pyrite to pyrrhotite and S released during the degradation of organic matter. In the presence of seawater SO 4, reduction of SO 4 contributes directly to H 2S production. Sedimentary organic matter acts as the reducing agent during pyrite and SO 4 reduction. Requisite acidity for the reduction of SO 4 is provided by Mg fixation during early-stage sediment alteration and by albite and calcite formation in Mg-free solutions. Organically derived CH 4 was characterized by δ 13C pdb values ranging between -20.8 and -23.1‰, whereas δ 13C pdb values for dissolved C organic ranged between -14.8 and -17.7%. Mass balance calculations indicate that δ13C values for organically derived CO 2 were ≥ - 14.8%. Residual solid sedimentary organic C showed small (≤ 0.7‰) depletions in 13C relative to the starting sediment. The experimental results are consistent with the isotopic and chemical composition of natural hydrothermal fluids and minerals at Guaymas Basin and permit us to better constrain sources and sinks for C and S species in subseafloor

  12. Variations in the chemical and stable isotope composition of carbon and sulfur species during organic-rich sediment alteration: An experimental and theoretical study of hydrothermal activity at guaymas basin, gulf of california

    Science.gov (United States)

    Seewald, Jeffrey S.; Seyfried, W.E.; Shanks, Wayne C.

    1994-01-01

    Organic-rich diatomaceous ooze was reacted with seawater and a Na-Ca-K-Cl fluid of seawater chlorinity at 325-400??C, 400-500 bars, and fluid/sediment mass ratios of 1.56-2.35 to constrain factors regulating the abundance and stable isotope composition of C and S species during hydrothermal alteration of sediment from Guaymas Basin, Gulf of California. Alteration of inorganic and organic sedimentary components resulted in extensive exchange reactions, the release of abundant H2S, CO2, CH4, and Corganic, to solution, and recrystallization of the sediment to an assemblage containing albitic plagioclase, quartz, pyrrhotite, and calcite. The ??34Scdt values of dissolved H2S varied from -10.9 to +4.3??? during seawater-sediment interaction at 325 and 400??C and from -16.5 to -9.0??? during Na-Ca-K-Cl fluid-sediment interaction at 325 and 375??C. In the absence of seawater SO4, H2S is derived from both the transformation of pyrite to pyrrhotite and S released during the degradation of organic matter. In the presence of seawater SO4, reduction of SO4 contributes directly to H2S production. Sedimentary organic matter acts as the reducing agent during pyrite and SO4 reduction. Requisite acidity for the reduction of SO4 is provided by Mg fixation during early-stage sediment alteration and by albite and calcite formation in Mg-free solutions. Organically derived CH4 was characterized by ??13Cpdb values ranging between -20.8 and -23.1???, whereas ??13Cpdb values for dissolved Corganic ranged between -14.8 and -17.7%. Mass balance calculations indicate that ??13C values for organically derived CO2 were ??? - 14.8%. Residual solid sedimentary organic C showed small (??? 0.7???) depletions in 13C relative to the starting sediment. The experimental results are consistent with the isotopic and chemical composition of natural hydrothermal fluids and minerals at Guaymas Basin and permit us to better constrain sources and sinks for C and S species in subseafloor hydrothermal systems

  13. Variation of carbon isotope fractionation in hydrogenotrophic methanogenic microbial cultures and environmental samples at different energy status

    NARCIS (Netherlands)

    Penning, H.; Plugge, C.M.; Galand, P.E.; Conrad, R.

    2005-01-01

    Methane is a major product of anaerobic degradation of organic matter and an important greenhouse gas. Its stable carbon isotope composition can be used to reveal active methanogenic pathways, if associated isotope fractionation factors are known. To clarify the causes that lead to the wide variatio

  14. Quantification of in Situ Biodegradation Rate Constants Using a Novel Combined Isotope Approach

    Science.gov (United States)

    Blum, P.; Sültenfuß, J.; Martus, P.

    2014-12-01

    Numerous studies have shown the enormous potential of the compound-specific isotope analysis (CSIA) for studying the biodegradation of organic compounds such as monoaromatic hydrocarbons (BTEX), polyaromatic hydrocarbons (PAH), chlorinated solvents and other organic contaminants and environmental transformation mechanisms in groundwater. In addition, two-dimensional isotope analysis such as carbon and hydrogen have been successfully studied indicating the potential to also investigate site-specific reaction mechanisms. The main objective of the current study however is to quantify real effective in situ biodegradation rate constants in a coal-tar contaminated aquifer by combining compound-specific isotope analysis (CSIA) and tracer-based (3H-3He) ground-water dating (TGD). Hence, groundwater samples are used to determine groundwater residence times, and carbon and hydrogen stable isotopes are analyzed for selected BTEX and PAH. The results of the hydrogen stable isotopes surprisingly indicate no isotope fractionation and therefore no biodegradation. In contrast, for stable carbon isotopes of selected BTEX such as o-xylene and toluene, isotope shifts are detected indicating active biodegradation under sulfate-reducing conditions. These and previous results of stable carbon isotopes show that only for o-xylene a clear evidence for biodegradation is possible for the studied site. Nevertheless, in combining these results with the groundwater residence times, which range between 1 year for the shallow wells (20 m below surface) and 41 years for the deeper wells (40 m below surface), it is feasible to effectively determine in situ biodegradation rate constants for o-xylene. Conversely, the outcome also evidently demonstrate the major limitations of the novel combined isotope approach for a successful implementation of monitored natural attenuation (MNA) at such field sites.

  15. Thermal Neutron Capture onto the Stable Tungsten Isotopes

    Directory of Open Access Journals (Sweden)

    Nichols A.

    2012-02-01

    Full Text Available Thermal neutron-capture measurements of the stable tungsten isotopes have been carried out using the guided thermal-neutron beam at the Budapest Reactor. Prompt singles spectra were collected and analyzed using the HYPERMET γ-ray analysis software package for the compound tungsten systems 183W, 184W, and 187W, prepared from isotopically-enriched samples of 182W, 183W, and 186W, respectively. These new data provide both confirmation and new insights into the decay schemes and structure of the tungsten isotopes reported in the Evaluated Gamma-ray Activation File based upon previous elemental analysis. The experimental data have also been compared to Monte Carlo simulations of γ-ray emission following the thermal neutron-capture process using the statistical-decay code DICEBOX. Together, the experimental cross sections and modeledfeeding contribution from the quasi continuum, have been used to determine the total radiative thermal neutron-capture cross sections for the tungsten isotopes and provide improved decay-scheme information for the structural- and neutron-data libraries.

  16. Inner radiation belt source of helium and heavy hydrogen isotopes

    Science.gov (United States)

    Leonov, A. A.; Galper, A. M.; Koldashov, S. V.; Mikhailov, V. V.; Casolino, M.; Picozza, P.; Sparvoli, R.

    Nuclear interactions between inner zone protons and atoms in the upper atmosphere provide the main source of energetic H and He isotopes nuclei in the radiation belt. This paper reports on the specified calculations of these isotope intensities using various inner zone proton intensity models (AP-8 and SAMPEX/PET PSB97), the atmosphere drift-averaged composition and density model MSIS-90, and cross-sections of the interaction processes from the GNASH nuclear model code. To calculate drift-averaged densities and energy losses of secondaries, the particles were tracked in the geomagnetic field (modelled through IGRF-95) by integrating numerically the equation of the motion. The calculations take into account the kinematics of nuclear interactions along the whole trajectory of trapped proton. The comparison with new data obtained from the experiments on board RESURS-04 and MITA satellites and with data from SAMPEX and CRRES satellites taken during different phases of solar activity shows that the upper atmosphere is a sufficient source for inner zone helium and heavy hydrogen isotopes. The calculation results are energy spectra and angular distributions of light nuclear isotopes in the inner radiation belt that may be used to develop helium inner radiation belt model and to evaluate their contribution to SEU (single event upset) rates.

  17. Nitrogen and Oxygen Isotopes of Low-Level Nitrate in Groundwater For Environmental Forensics

    Science.gov (United States)

    Wang, Y.

    2009-05-01

    Sources of nitrate in water from human activities include fertilizers, animal feedlots, septic systems, wastewater treatment lagoons, animal wastes, industrial wastes and food processing wastes. Nitrogen and Oxygen isotopic analysis of nitrate in groundwater is essential to source identification and environmental forensics as nitrate from different sources carry distinctly different N and O isotopic compositions. Nitrate is extracted from groundwater samples and converted into AgNO3 using ion exchange techniques. The purified AgNO3 is then broken down into N2 and CO for N and O isotopic measurement. Since nitrate concentrations in natural ground waters are usually less than 2 mg/L, however, such method has been limited by minimum sample size it requires, in liters, which is highly nitrate concentration dependent. Here we report a TurboVap- Denitrifier method for N and O isotopic measurement of low-level dissolved nitrate, based on sample evaporation and isotopic analysis of nitrous oxide generated from nitrate by denitrifying bacteria that lack N2O- reductase activity. For most groundwater samples with mg/L-level of nitrate direct injection of water samples in mLs is applied. The volume of sample is adjusted according to its nitrate concentration to achieve a final sample size optimal for the system. For water samples with ug/L-level of nitrate, nitrate is highly concentrated using a TurboVap evaporator, followed by isotopic measurement with Denitrifier method. Benefits of TurboVap- Denitrifier method include high sensitivity and better precision in both isotopic data. This method applies to both freshwater and seawater. The analyses of isotopic reference materials in nitrate-free de-ionized water and seawater are included as method controls to correct for any blank effects. The isotopic data from groundwater and ocean profiles demonstrate the consistency of the data produced by the TurboVap-Denitrifier method.

  18. Pb isotopes during mingling and melting

    DEFF Research Database (Denmark)

    Waight, Tod Earle; Lesher, Charles E.

    2010-01-01

    Pb isotopic data are presented for hybrid rocks formed by mingling between mantle-derived tholeiitic magma of the Eocene Miki Fjord macrodike (East Greenland) and melt derived from the adjacent Precambrian basement. Bulk mixing and AFC processes between end-members readily identified in the field...... fail to model the Pb isotope systematics. Selective contamination during diffusional exchange, which can explain the complex Sr and Nd isotope compositions of the hybrid rocks (Blichert-Toft et al., 1992), cannot fully account for the variability of the Pb isotopic data using the identified crustal end......-members. The crustal anatectic end-member, although similar in Sr and Nd isotope composition, has a markedly different Pb isotopic composition than its source gneiss. The differences are consistent with preferential incorporation of radiogenic Pb from accessory phases such as metamict zircon or loosely-bound Pb from...

  19. Isotopic constraints of mantle derived carbonatitic melts from Calatrava, Spain

    Science.gov (United States)

    Humphreys, E. R.; Bailey, K.; Hawkesworth, C. J.; Wall, F.; Avanzinelli, R.

    2010-12-01

    Carbonatite volcanism is typically associated both spatially and temporally with alkaline, ultramafic volcanism (Woolley & Church, 2005). Recent discoveries in Calatrava, Spain illustrate the activity of carbonatite in the source melts of leucitite volcanism. Melilitite pyroclastic lapilli tuffs also show a clear association with volcanic carbonate. Carbonatitic activity has been shown to initiate at depths greater than 100km (Humphreys et al., 2010) despite a maximum estimate of lithospheric thickness of 80km. The presence of aragonite and abundant mantle xenoliths in many deposits are clear indication of the rapid emplacement rates of such magmas. Carbonatitic activity in the source of the leucitite melts is indicated by carbonate inclusions within olivine xenocrysts and the presence of occasional carbonatite lenses. The composition of lead and strontium isotope ratios in the bulk rock, and spatially resolved analysis of carbonate from the groundmass and from inclusions demonstrates a genetic affinity between the inclusions and the related bulk rock composition. Lead and strontium isotopic analysis suggest that such melts do not represent the composition of convecting asthenospheric mantle. 87Sr/86Sr (0.7055-0.7068) values are higher than those of MORB and most OIB. Lead isotope ratios show a trend displaced to higher 207Pb/204Pb relative to MORB and OIB. Carbonate inclusions have less radiogenic lead values than the more radiogenic bulk rocks. Our data indicate that carbonatitic activity in the mantle is intrinsic in the generation of the leucitite lava. However, petrographic and isotopic evidence suggest a complex melt history. Olivine xenocrysts are not in equilibrium with the host leucitite, despite inclusions within olivine showing an isotopic affinity to the bulk rock. We suggest that in this example, alkaline magmatism was induced by the presence of CO2 in the mantle source. Isotopic evidence shows that the mantle producing such melts was not

  20. Research Progress of Series of Uranium Isotope Ratios Measured by AMS

    Institute of Scientific and Technical Information of China (English)

    LIN; De-yu; WANG; Chen; HUANG; Guo-rui; DONG; Ke-jun; HE; Ming; RUAN; Xiang-dong; WU; Shao-yong; ZHAO; Yong-gang; LI; Li-li; DOU; Liang; XIE; Lin-bo; WANG; Xiao-bo; YANG; Xu-ran; WANG; Xiao-ming; LAN; Xiao-xi; JIANG; Shan

    2012-01-01

    <正>The nuclear safeguards system which is used to monitor compliance with the Nuclear Non-proliferation Treaty relies to a significant degree on the analysis of environmental samples. Undeclared nuclear activities can be detected through determination of the isotopic ratios of uranium and plutonium in such samples. It is necessary to be able to measure the full suite of uranium isotopes (234U,

  1. Normalization of oxygen and hydrogen isotope data

    Science.gov (United States)

    Coplen, T.B.

    1988-01-01

    To resolve confusion due to expression of isotopic data from different laboratories on non-corresponding scales, oxygen isotope analyses of all substances can be expressed relative to VSMOW or VPDB (Vienna Peedee belemnite) on scales normalized such that the ??18O of SLAP is -55.5% relative to VSMOW. H3+ contribution in hydrogen isotope ratio analysis can be easily determined using two gaseous reference samples that differ greatly in deuterium content. ?? 1988.

  2. Silicon isotopes: from cosmos to benthos

    OpenAIRE

    Chakrabarti, Ramananda

    2015-01-01

    Silicon is the second most abundant element on the Earth and one of the more abundant elements in our Solar System. Variations in the relative abundance of the stable isotopes of Si (Si isotope fractionation) in different natural reservoirs, both terrestrial (surface and deep Earth) as well as extra-terrestrial (e.g. meteorites, lunar samples), are a powerful tracer of present and past processes involving abiotic as well as biotic systems. The versatility of the Si isotope tracer is reflected...

  3. Production of radioactive isotopes from stable isotopes, for nuclear medicine; A partir d`isotopes stables, production d`isotopes radioactifs pour la medecine nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Bourdoiseau, M. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Office des Rayonnements Ionisants

    1994-12-31

    Around 15 radioactive isotopes only are used for nuclear medicine diagnosis (kinetics or preferential fixation in the body); characteristics of these {gamma} and {beta}-minus emitters are presented: period, energy, production mode (isotopic filiation, fission product separation, cyclotron, reactor); details are given on applications, production mode, properties and consumption of various isotopes: Technetium 99m, Thallium 201, Iodine 123, Indium 111, Gallium 67, Rhenium 186, Erbium 169, Yttrium 90, Iron 59, Chromium 51, Krypton 81m. 1 tab.

  4. Quantitative microbial ecology through stable isotope probing.

    Science.gov (United States)

    Hungate, Bruce A; Mau, Rebecca L; Schwartz, Egbert; Caporaso, J Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J; Liu, Cindy M; McHugh, Theresa A; Marks, Jane C; Morrissey, Ember M; Price, Lance B

    2015-11-01

    Bacteria grow and transform elements at different rates, and as yet, quantifying this variation in the environment is difficult. Determining isotope enrichment with fine taxonomic resolution after exposure to isotope tracers could help, but there are few suitable techniques. We propose a modification to stable isotope probing (SIP) that enables the isotopic composition of DNA from individual bacterial taxa after exposure to isotope tracers to be determined. In our modification, after isopycnic centrifugation, DNA is collected in multiple density fractions, and each fraction is sequenced separately. Taxon-specific density curves are produced for labeled and nonlabeled treatments, from which the shift in density for each individual taxon in response to isotope labeling is calculated. Expressing each taxon's density shift relative to that taxon's density measured without isotope enrichment accounts for the influence of nucleic acid composition on density and isolates the influence of isotope tracer assimilation. The shift in density translates quantitatively to isotopic enrichment. Because this revision to SIP allows quantitative measurements of isotope enrichment, we propose to call it quantitative stable isotope probing (qSIP). We demonstrated qSIP using soil incubations, in which soil bacteria exhibited strong taxonomic variations in (18)O and (13)C composition after exposure to [(18)O]water or [(13)C]glucose. The addition of glucose increased the assimilation of (18)O into DNA from [(18)O]water. However, the increase in (18)O assimilation was greater than expected based on utilization of glucose-derived carbon alone, because the addition of glucose indirectly stimulated bacteria to utilize other substrates for growth. This example illustrates the benefit of a quantitative approach to stable isotope probing.

  5. The trend of stable isotope separation

    Energy Technology Data Exchange (ETDEWEB)

    Yonekawa, Shigeru [Power Reactor and Nuclear Fuel Development Corp., Kamisaibara, Okayama (Japan). Ningyo Toge Works; Aoki, Eiji; Yato, Yumio

    1994-12-01

    Recently, stable isotopes are used in the field of medical science, nuclear physics, environmental science and agriculture. This report reviews the present status of stable isotope enrichment in ORNL, Urenco, Russia and PNC. Further the utilization method of the stable isotopes in the field of medical science, nuclear power and material science are described, and the application possibility of Laser separation method and Gas Centrifuge method are estimated. There are many overseas actual results of stable isotope separation with Gas Centrifuge method, therefore this method is possible enough in principle. (author).

  6. Scattering lengths of calcium and barium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Dammalapati, U.; Willmann, L.; Knoop, S. [Kernfysisch Versneller Instituut (KVI), University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); LaserLaB Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands)

    2011-11-15

    We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba) in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca does not provide other isotopes alternative to the recently Bose condensed {sup 40}Ca that suffers strong losses because of a very large scattering length. For Ba we show by using a model potential that the even isotopes cover a broad range of scattering lengths, opening the possibility of BEC for at least one of the isotopes.

  7. A solvent extraction technique for the isotopic measurement of dissolved copper in seawater

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Claire M., E-mail: claire.thompson@anu.edu.au; Ellwood, Michael J., E-mail: michael.ellwood@anu.edu.au; Wille, Martin, E-mail: martin.wille@uni-tuebingen.de

    2013-05-02

    Graphical abstract: -- Highlights: •A new sample preparation method for seawater copper isotopic analysis (δ{sup 65}Cu). •Solvent-extraction was used to pre-concentrate metals from seawater samples. •Anion-exchange was used to purify copper from the metal-rich extract. •δ{sup 65}Cu was measured in the north Tasman Sea. •Seawater δ{sup 65}Cu may be linked to marine biological activity. -- Abstract: Stable copper (Cu) isotope geochemistry provides a new perspective for investigating and understanding Cu speciation and biogeochemical Cu cycling in seawater. In this work, sample preparation for isotopic analysis employed solvent-extraction with amino pyrollidine dithiocarbamate/diethyl dithiocarbamate (APDC/DDC), coupled with a nitric acid back-extraction, to concentrate Cu from seawater. This was followed by Cu-purification using anion-exchange. This straightforward technique is high yielding and fractionation free for Cu and allows precise measurement of the seawater Cu isotopic composition using multi-collector inductively coupled plasma mass-spectrometry. A deep-sea profile measured in the oligotrophic north Tasman Sea shows fractionation in the Cu isotopic signature in the photic zone but is relatively homogenised at depth. A minima in the Cu isotopic profile correlates with the chlorophyll a maximum at the site. These results indicate that a range of processes are likely to fractionate stable Cu isotopes in seawater.

  8. Iron isotope fractionation during Fe uptake and translocation in alpine plants.

    Science.gov (United States)

    Kiczka, Mirjam; Wiederhold, Jan G; Kraemer, Stephan M; Bourdon, Bernard; Kretzschmar, Ruben

    2010-08-15

    The potential of stable Fe isotopes as a tracer for the biogeochemical Fe cycle depends on the understanding and quantification of the fractionation processes involved. Iron uptake and cycling by plants may influence Fe speciation in soils. Here, we determined the Fe isotopic composition of different plant parts including the complete root system of three alpine plant species (Oxyria digyna, Rumex scutatus, Agrostis gigantea) in a granitic glacier forefield, which allowed us, for the first time, to distinguish between uptake and in-plant fractionation processes. The overall range of fractionation was 4.5 per thousand in delta(56)Fe. Mass balance calculations demonstrated that fractionation toward lighter Fe isotopic composition occurred in two steps during uptake: (1) before active uptake, probably during mineral dissolution and (2) during selective uptake of Fe at the plasma membrane with an enrichment factor of -1.0 to -1.7 per thousand for all three species. Iron isotopes were further fractionated during remobilization from old into new plant tissue, which changed the isotopic composition of leaves and flowers over the season. This study demonstrates the potential of Fe isotopes as a new tool in plant nutrition studies but also reveals challenges for the future application of Fe isotope signatures in soil-plant environments.

  9. Controlling factors of rainwater and water vapor isotopes at Bangalore, India: Constraints from observations in 2013 Indian monsoon

    Science.gov (United States)

    Rahul, P.; Ghosh, Prosenjit; Bhattacharya, S. K.; Yoshimura, Kei

    2016-12-01

    Isotopic ratios of rainwaters are believed to decrease with the amount of rainfall. However, analyses of the isotopic composition of rainwater and water vapor samples collected from Bangalore during the monsoon period of 2013 fail to show any simple relationship with the local meteorological parameters whereas show good correlation with the regional integrated convective activity. The correlation is particularly high when the averaging is done over the preceding 8 to 15 days, showing the influence of mixing or residence time scale of atmospheric moisture. This observation emphasizes the role of regional atmospheric circulation driving the isotopic values. A comparison between observed isotope ratios in water vapor and rainwater with Isotope-enabled Global Spectral Model shows discrepancies between the two. The observed values are relatively enriched, indicating a systematic bias in the model values. The higher observed values suggest underestimation of the evaporation in the model, which we estimate to be about 28 ± 15% on average. Simultaneous analyses of rainwater and water vapor isotopic composition again show definitive presence of raindrop evaporation (31 ± 14%). We also documented a distinct pattern of isotopic variation in six samples collected at Bangalore due to mixing of vapor from a cyclonic system in close proximity that originated from the Bay of Bengal. It seems that large-scale isotopic depletion occurs during cyclones caused by Rayleigh fractionation due to massive rainout. These results demonstrate the power of rainwater and water vapor isotope monitoring to elucidate the genesis and dynamics of water recycling within synoptic-scale monsoon systems.

  10. The Application of Methane Clumped Isotope Measurements to Determine the Source of Large Methane Seeps in Alaskan Lakes

    Science.gov (United States)

    Douglas, P. M.; Stolper, D. A.; Eiler, J. M.; Sessions, A. L.; Walter Anthony, K. M.

    2014-12-01

    Natural methane emissions from the Arctic present an important potential feedback to global warming. Arctic methane emissions may come from either active microbial sources or from deep fossil reservoirs released by the thawing of permafrost and melting of glaciers. It is often difficult to distinguish between and quantify contributions from these methane sources based on stable isotope data. Analyses of methane clumped isotopes (isotopologues with two or more rare isotopes such as 13CH3D) can complement traditional stable isotope-based classifications of methane sources. This is because clumped isotope abundances (for isotopically equilibrated systems) are a function of temperature and can be used to identify pathways of methane generation. Additionally, distinctive effects of mixing on clumped isotope abundances make this analysis valuable for determining the origins of mixed gasses. We find large variability in clumped isotope compositions of methane from seeps in several lakes, including thermokarst lakes, across Alaska. At Lake Sukok in northern Alaska we observe the emission of dominantly thermogenic methane, with a formation temperature of at least 100° C. At several other lakes we find evidence for mixing between thermogenic methane and biogenic methane that forms in low-temperature isotopic equilibrium. For example, at Eyak Lake in southeastern Alaska, analysis of three methane samples results in a distinctive isotopic mixing line between a high-temperature end-member that formed between 100-170° C, and a biogenic end-member that formed in isotopic equilibrium between 0-20° C. In this respect, biogenic methane in these lakes resembles observations from marine gas seeps, oil degradation, and sub-surface aquifers. Interestingly, at Goldstream Lake in interior Alaska, methane with strongly depleted clumped-isotope abundances, indicative of disequilibrium gas formation, is found, similar to observations from methanogen culture experiments.

  11. Modeling the carbon isotope composition of bivalve shells (Invited)

    Science.gov (United States)

    Romanek, C.

    2010-12-01

    fractionation relations dictate that shell carbonate should be preferentially enriched in C-13 by 3 to 5 per mill (from 30° to 0°C) compared to EPF at a pH of 7.5. Anomalous positive excursions are rarely, if ever, observed in shell carbonate and they have yet to be associated with growth cessation markers in bivalves. The most likely explanation for the lack of anomalous positive values is that the percentage of metabolic carbon increases in EPF when bivalves experience stressful condition. This influx of metabolic carbon is balanced to a measureable extent by the enhanced fractionation of carbon isotopes during shell deposition from EPF at relatively low pH. These two processes may be combined in a quantitative model to extract a historical record of metabolic activity from the carbon isotope profiles of bivalve shells.

  12. CO Isotopes in Planetary Nebulae

    OpenAIRE

    Balser, Dana S.; McMullin, Joseph P.; Wilson, T. L.

    2002-01-01

    Standard stellar evolution theory is inconsistent with the observed isotopic carbon ratio, 12C/13C, in evolved stars. This theory is also inconsistent with the 3He/H abundance ratios observed in Galactic HII regions, when combined with chemical evolution theory. These discrepancies have been attributed to an extra, non-standard mixing which further processes material during the RGB and should lower both the 12C/13C and 3He/H abundance ratios for stars with masses < 2 solar masses. Measurement...

  13. Silicon isotope fractionation during magmatic differentiation

    Science.gov (United States)

    Savage, Paul S.; Georg, R. Bastian; Williams, Helen M.; Burton, Kevin W.; Halliday, Alex N.

    2011-10-01

    The Si isotopic composition of Earth's mantle is thought to be homogeneous (δ 30Si = -0.29 ± 0.08‰, 2 s.d.) and not greatly affected by partial melting and recycling. Previous analyses of evolved igneous material indicate that such rocks are isotopically heavy relative to the mantle. To understand this variation, it is necessary to investigate the degree of Si isotopic fractionation that takes place during magmatic differentiation. Here we report Si isotopic compositions of lavas from Hekla volcano, Iceland, which has formed in a region devoid of old, geochemically diverse crust. We show that Si isotopic composition varies linearly as a function of silica content, with more differentiated rocks possessing heavier isotopic compositions. Data for samples from the Afar Rift Zone, as well as various igneous USGS standards are collinear with the Hekla trend, providing evidence of a fundamental relationship between magmatic differentiation and Si isotopes. The effect of fractionation has been tested by studying cumulates from the Skaergaard Complex, which show that olivine and pyroxene are isotopically light, and plagioclase heavy, relative to the Si isotopic composition of the Earth's mantle. Therefore, Si isotopes can be utilised to model the competing effects of mafic and felsic mineral fractionation in evolving silicate liquids and cumulates. At an average SiO 2 content of ˜60 wt.%, the predicted δ 30Si value of the continental crust that should result from magmatic fractionation alone is -0.23 ± 0.05‰ (2 s.e.), barely heavier than the mantle. This is, at most, a maximum estimate, as this does not take into account weathered material whose formation drives the products toward lighter δ 30Si values. Mass balance calculations suggest that removal of continental crust of this composition from the upper mantle will not affect the Si isotopic composition of the mantle.

  14. Exploring the isotopic niche: isotopic variance, physiological incorporation, and the temporal dynamics of foraging

    Directory of Open Access Journals (Sweden)

    Justin Douglas Yeakel

    2016-01-01

    Full Text Available Consumer foraging behaviors are dynamic, changing in response to prey availability, seasonality, competition, and even the consumer's physiological state. The isotopic composition of a consumer is a product of these factors as well as the isotopic `landscape' of its prey, i.e. the isotopic mixing space. Stable isotope mixing models are used to back-calculate the most likely proportional contribution of a set of prey to a consumer's diet based on their respective isotopic distributions, however they are disconnected from ecological process. Here we build a mechanistic framework that links the ecological and physiological processes of an individual consumer to the isotopic distribution that describes its diet, and ultimately to the isotopic composition of its own tissues, defined as its `isotopic niche’. By coupling these processes, we systematically investigate under what conditions the isotopic niche of a consumer changes as a function of both the geometric properties of its mixing space and foraging strategies that may be static or dynamic over time. Results of our derivations reveal general insight into the conditions impacting isotopic niche width as a function of consumer specialization on prey, as well as the consumer's ability to transition between diets over time. We show analytically that moderate specialization on isotopically unique prey can serve to maximize a consumer's isotopic niche width, while temporally dynamic diets will tend to result in peak isotopic variance during dietary transitions. We demonstrate the relevance of our theoretical findings by examining a marine system composed of nine invertebrate species commonly consumed by sea otters. In general, our analytical framework highlights the complex interplay of mixing space geometry and consumer dietary behavior in driving expansion and contraction of the isotopic niche. Because this approach is established on ecological mechanism, it is well-suited for enhancing the

  15. Study of medical isotope production facility stack emissions and noble gas isotopic signature using automatic gamma-spectra analysis platform

    Science.gov (United States)

    Zhang, Weihua; Hoffmann, Emmy; Ungar, Kurt; Dolinar, George; Miley, Harry; Mekarski, Pawel; Schrom, Brian; Hoffman, Ian; Lawrie, Ryan; Loosz, Tom

    2013-04-01

    The nuclear industry emissions of the four CTBT (Comprehensive Nuclear-Test-Ban Treaty) relevant radioxenon isotopes are unavoidably detected by the IMS along with possible treaty violations. Another civil source of radioxenon emissions which contributes to the global background is radiopharmaceutical production companies. To better understand the source terms of these background emissions, a joint project between HC, ANSTO, PNNL and CRL was formed to install real-time detection systems to support 135Xe, 133Xe, 131mXe and 133mXe measurements at the ANSTO and CRL 99Mo production facility stacks as well as the CANDU (CANada Deuterium Uranium) primary coolant monitoring system at CRL. At each site, high resolution gamma spectra were collected every 15 minutes using a HPGe detector to continuously monitor a bypass feed from the stack or CANDU primary coolant system as it passed through a sampling cell. HC also conducted atmospheric monitoring for radioxenon at approximately 200 km distant from CRL. A program was written to transfer each spectrum into a text file format suitable for the automatic gamma-spectra analysis platform and then email the file to a server. Once the email was received by the server, it was automatically analysed with the gamma-spectrum software UniSampo/Shaman to perform radionuclide identification and activity calculation for a large number of gamma-spectra in a short period of time (less than 10 seconds per spectrum). The results of nuclide activity together with other spectrum parameters were saved into the Linssi database. This database contains a large amount of radionuclide information which is a valuable resource for the analysis of radionuclide distribution within the noble gas fission product emissions. The results could be useful to identify the specific mechanisms of the activity release. The isotopic signatures of the various radioxenon species can be determined as a function of release time. Comparison of 133mXe and 133Xe activity

  16. ISOTOPES

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    1 A New Therapeutic Agent for Radiation Synovectomy: Preparation of 166Ho-EDTMP-HA Bai Hongsheng Jin Xiaohai Du Jin Wang Fan Chen Daming Fan Hongqiang Cheng Zhen In order to treat the patient with inflammatory synovial disease, HA particle is labeled with 166Ho by EDTMP under the condition of pH6.0-8.0 and vibration time 15 min, its labeling efficiency is more than 98%, the size of particle is mainly in the range of 2-5 μm. The absorbed capacity is 5 mg Ho per 1g HA. Study on stability of 166Ho-EDTMP-HA in vitro shows that loss of 166Ho is less than 2% for166Ho-EDTMP-HA incubated 72 h in the 0.9% saline and 1% BSA solution at 37 ℃ .Biodistribution in vivo and extra articular leakage are investigated following injection of 166Ho-EDTMP-HA into knee of normal rabbits. The experimental results show that the extra leakage of 166Ho-EDTMP-HA is 0.32% at 48 h post-injection, most of 166Ho radioactivity leaked from the knee joint is excreted in the urine. 99% of 166Ho radioactivity is retained in the knee joint of rabbits. Thereby 166Ho-EDTMP-HA, as a new therapeutical agent of radiation synovectomy, had a value of further clinical study.

  17. Methane isotope records from Antarctic firn air

    Science.gov (United States)

    Sowers, T. A.; Battle, M.

    2007-12-01

    The earth's climate is directly influenced by changes in the atmospheric loading of trace "greenhouse" gases. Methane is an important greenhouse gas whose atmospheric concentration has doubled over the last century as a result of various anthropogenic activities. Understanding the methane cycle in the recent past is a compelling scientific problem because increasing methane levels in the modern atmosphere will contribute to predicted future warming. The only source of air that allows us to study the long-term cycles of these gases is found in the trapped gases in ice cores and the interstitial pore spaces in firn from the central portions of Greenland and Antarctica. Firn air samples, retrieved from the South Pole in 1995 and 2001, were analyzed for δ13CH4. In December of 2005, another suite of firn air samples was recovered from the new US deep coring site located along the west Antarctic divide (WAIS D) which were analyzed for both δ13C and δ D of CH4. In general, replicate flasks were sampled from each depth from two separate drillings each year. The precision of the δ13C and δ D analyses is generally better than ± 0.2‰ and 2‰, respectively, with surface values in good agreement with NOAA (INSTAAR) biweekly flask measurements from South Pole. In all cases, δ13C and δD values decrease gradually with depth below the convective zone. However, these isotopes and CH4 mixing ratios decline sharply below the "lock-in" depth. The measured firn air profiles are primarily the result of three factors. First, tropospheric changes drive compositional changes in the near-surface convective layer that are subsequently mixed downward due to bulk air-movement within the shallow firn. Secondly, gases are mixed below the convective zone solely by molecular diffusion, leading to the gradual downward propagation of the compositional changes in the convective layer. Finally, differential gravitational settling causes the heavier atmospheric constituents (both elemental

  18. Isotope Program Report June FY2016

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Jr, Benjamin E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Egle, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-01

    Isotope Program Monthly Highlights are briefly described. These include data on isotopes shipped, updates on equipment fabrication and testing, a potential new approach for nondestructive measurement of the amount of Cf-252 deposited on a surface, and efforts to recover and purify uranium-234 obtained from old PuBe sources.

  19. Advanced Mass Spectrometers for Hydrogen Isotope Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Chastagner, P.

    2001-08-01

    This report is a summary of the results of a joint Savannah River Laboratory (SRL) - Savannah River Plant (SRP) ''Hydrogen Isotope Mass Spectrometer Evaluation Program''. The program was undertaken to evaluate two prototype hydrogen isotope mass spectrometers and obtain sufficient data to permit SRP personnel to specify the mass spectrometers to replace obsolete instruments.

  20. Applications of stable isotopes in clinical pharmacology

    NARCIS (Netherlands)

    Schellekens, Reinout C A; Stellaard, Frans; Woerdenbag, Herman J; Frijlink, Henderik W; Kosterink, Jos G W

    2011-01-01

    This review aims to present an overview of the application of stable isotope technology in clinical pharmacology. Three main categories of stable isotope technology can be distinguished in clinical pharmacology. Firstly, it is applied in the assessment of drug pharmacology to determine the pharmacok

  1. Magnesium isotope geochemistry in arc volcanism

    Science.gov (United States)

    Teng, Fang-Zhen; Hu, Yan; Chauvel, Catherine

    2016-06-01

    Incorporation of subducted slab in arc volcanism plays an important role in producing the geochemical and isotopic variations in arc lavas. The mechanism and process by which the slab materials are incorporated, however, are still uncertain. Here, we report, to our knowledge, the first set of Mg isotopic data for a suite of arc lava samples from Martinique Island in the Lesser Antilles arc, which displays one of the most extreme geochemical and isotopic ranges, although the origin of this variability is still highly debated. We find the δ26Mg of the Martinique Island lavas varies from -0.25 to -0.10, in contrast to the narrow range that characterizes the mantle (-0.25 ± 0.04, 2 SD). These high δ26Mg values suggest the incorporation of isotopically heavy Mg from the subducted slab. The large contrast in MgO content between peridotite, basalt, and sediment makes direct mixing between sediment and peridotite, or assimilation by arc crust sediment, unlikely to be the main mechanism to modify Mg isotopes. Instead, the heavy Mg isotopic signature of the Martinique arc lavas requires that the overall composition of the mantle wedge is buffered and modified by the preferential addition of heavy Mg isotopes from fluids released from the altered subducted slab during fluid-mantle interaction. This, in turn, suggests transfer of a large amount of fluid-mobile elements from the subducting slab to the mantle wedge and makes Mg isotopes an excellent tracer of deep fluid migration.

  2. Magnesium isotope geochemistry in arc volcanism.

    Science.gov (United States)

    Teng, Fang-Zhen; Hu, Yan; Chauvel, Catherine

    2016-06-28

    Incorporation of subducted slab in arc volcanism plays an important role in producing the geochemical and isotopic variations in arc lavas. The mechanism and process by which the slab materials are incorporated, however, are still uncertain. Here, we report, to our knowledge, the first set of Mg isotopic data for a suite of arc lava samples from Martinique Island in the Lesser Antilles arc, which displays one of the most extreme geochemical and isotopic ranges, although the origin of this variability is still highly debated. We find the δ(26)Mg of the Martinique Island lavas varies from -0.25 to -0.10, in contrast to the narrow range that characterizes the mantle (-0.25 ± 0.04, 2 SD). These high δ(26)Mg values suggest the incorporation of isotopically heavy Mg from the subducted slab. The large contrast in MgO content between peridotite, basalt, and sediment makes direct mixing between sediment and peridotite, or assimilation by arc crust sediment, unlikely to be the main mechanism to modify Mg isotopes. Instead, the heavy Mg isotopic signature of the Martinique arc lavas requires that the overall composition of the mantle wedge is buffered and modified by the preferential addition of heavy Mg isotopes from fluids released from the altered subducted slab during fluid-mantle interaction. This, in turn, suggests transfer of a large amount of fluid-mobile elements from the subducting slab to the mantle wedge and makes Mg isotopes an excellent tracer of deep fluid migration.

  3. The isotopic dipole moment of HDO

    Energy Technology Data Exchange (ETDEWEB)

    Assafrao, Denise; Mohallem, Jose R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, CP 702, 30123-970, Belo Horizonte, MG (Brazil)

    2007-03-14

    An adiabatic variational approximation is used to study the monodeuterated water molecule, HDO, accounting for the isotopic effect. The isotopic dipole moment, pointing from D to H, is then calculated for the first time, yielding (1.5 {+-} 0.1) x 10{sup -3} Debye, being helpful in the interpretation of experiments. (fast track communication)

  4. Atomic lithium vapor laser isotope separation

    CERN Document Server

    Olivares, I E

    2002-01-01

    An atomic vapor laser isotope separation in lithium was performed using tunable diode lasers. The method permits also the separation of the isotopes between the sup 6 LiD sub 2 and the sup 7 LiD sub 1 lines using a self-made mass separator which includes a magnetic sector and an ion beam designed for lithium. (Author)

  5. Cadmium isotope fractionation of materials derived from various industrial processes.

    Science.gov (United States)

    Martinková, Eva; Chrastný, Vladislav; Francová, Michaela; Šípková, Adéla; Čuřík, Jan; Myška, Oldřich; Mižič, Lukáš

    2016-01-25

    Our study represents ϵ(114/110) Cd NIST3108 values of materials resulting from anthropogenic activities such as coal burning, smelting, refining, metal coating, and the glass industry. Additionally, primary sources (ore samples, pigment, coal) processed in the industrial premises were studied. Two sphalerites, galena, coal and pigment samples exhibited ϵ(114/110) CdNIST3108 values of 1.0±0.2, 0.2±0.2, 1.3±0.1, -2.3±0.2 and -0.1±0.3, respectively. In general, all studied industrial processes were accompanied by Cd isotope fractionation. Most of the industrial materials studied were clearly distinguishable from the samples used as a primary source based on ϵ(114/110) Cd NIST3108 values. The heaviest ϵ(114/110) CdNIST3108 value of 58.6±0.9 was found for slag resulting from coal combustion, and the lightest ϵ(114/110) CdNIST3108 value of -23±2.5 was observed for waste material after Pb refinement. It is evident that ϵ(114/110) Cd NIST3108 values depend on technological processes, and in case of incomplete Cd transfer from source to final waste material, every industrial activity creates differences in Cd isotope composition. Our results show that Cd isotope analysis is a promising tool to track the origins of industrial waste products.

  6. Second international conference on isotopes. Conference proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, C.J. [ed.

    1997-10-01

    The Second International Conference on Isotopes (2ICI) was hosted by the Australian Nuclear Association in Sydney, NSW, Australia. The Theme of the Second Conference: Isotopes for Industry, Health and a Better Environment recognizes that isotopes have been used in these fields successfully for many years and offer prospects for increasing use in the future. The worldwide interest in the use of research reactors and accelerators and in applications of stable and radioactive isotopes, isotopic techniques and radiation in industry, agriculture, medicine, environmental studies and research in general, was considered. Other radiation issues including radiation protection and safety were also addressed. International and national overviews and subject reviews invited from leading experts were included to introduce the program of technical sessions. The invited papers were supported by contributions accepted from participants for oral and poster presentation. A Technical Exhibition was held in association with the Conference. This volume contains the full text or extended abstracts of papers number 61- to number 114

  7. Evidence for a catalytic six-membered cyclic transition state in aminolysis of 4-nitrophenyl 3,5-dinitrobenzoate in acetonitrile: comparative brønsted-type plot, entropy of activation, and deuterium kinetic isotope effects.

    Science.gov (United States)

    Um, Ik-Hwan; Kim, Min-Young; Bae, Ae-Ri; Dust, Julian M; Buncel, Erwin

    2015-01-02

    A kinetic study for reactions of 4-nitrophenyl 3,5-dinitrobenzoate (1a) with a series of cyclic secondary amines in acetonitrile is reported. Plots of the pseudo-first-order rate constant (kobsd) vs [amine] curve upward, while those of kobsd /[amine] vs [amine] exhibit excellent linear correlations with positive intercepts, indicating that the reaction proceeds through both uncatalyzed and catalyzed routes. Brønsted-type plots for uncatalyzed and catalyzed reactions are linear with βnuc = 1.03 and 0.69, respectively. The ΔH(⧧) and ΔS(⧧) values measured for the catalytic reaction with morpholine are -0.80 kcal/mol and -61.7 cal/(mol K), respectively. The negative ΔH(⧧) with a large negative ΔS(⧧) suggests that the reaction proceeds through a highly ordered transition state (i.e., a six-membered cyclic transition state, which includes a second amine molecule that accepts a proton from the aminium moiety of the zwitterionic tetrahedral intermediate and simultaneously donates a proton to the aryloxyl oxygen of the nucleofuge with concomitant C-OAr bond scission). This proposal is consistent with the smaller βnuc value for the catalyzed reaction as compared to the uncatalyzed reaction. An inverse deuterium kinetic isotope effect (DKIE) value of 0.93 and a contrasting normal primary DKIE value of 3.23 for the uncatalyzed and catalyzed routes, respectively, also support the proposed cyclic transition state.

  8. Using Stable Isotopes to Trace Microbial Hydrogen Production Pathways

    Science.gov (United States)

    Moran, J.; Hill, E.; Bartholomew, R.; Yang, H.; Shi, L.; Ostrom, N. E.; Gandhi, H.; Hegg, E.; Kreuzer, H.

    2010-12-01

    Biological H2 production by hydrogenase enzymes (H2ases) plays an important role in anaerobic microbial metabolism and community structure. Despite considerable progress in elucidating H2 metabolism, the regulation of and flux through key H2 production pathways remain largely undefined. Our goal is to improve understanding of biological H2 production by using H isotope ratios to dissect proton fluxes through different H2ase enzymes and from different substrates. We hypothesized that the isotope ratio of H2 produced by various hydrogenases (H2ase) would differ, and that the H isotope ratios would allow us to define the contribution of different enzymes when more than one is present in vivo. We chose Shewanella oneidensis (S.o.) MR-1, a facultative anaerobe capable of transferring electrons to a variety of terminal acceptors, including protons, as a model system for in vivo studies. S. o. encodes one [FeFe]- and one [NiFe]-H2ase. We purified three [FeFe]-H2ases (S.o., Clostridium pasteurianum, and Chlamydomonas reinhardtii) and two [NiFe]-H2ases (S. o. and Desulfovibrio fructosovorans) to test the isotope fractionation associated with activity by each enzyme in vitro. For in vivo analysis we used wild-type S.o. as well as electron transfer-deficient and H2ase-deficient strains. We employed batch cultures using lactate as an electron donor and O2 as an initial electron acceptor (with H2 production after O2 consumption). The five H2ases we tested all had a unique isotope fractionation. Measurements of H2 produced in vivo showed distinct periods of H2 production having isotope signatures consistent with in vitro results. Isotope data as well as studies of H2 production by mutants in the genes encoding either the [NiFe]-H2ase or the [FeFe]-H2ase, respectively, show that the [NiFe]- and [FeFe]- H2ases became active at different times. The [NiFe]-H2ase both produces and consumes H2 before the [FeFe]-H2ase becomes active. RNA analysis is consistent with up regulation of

  9. Inner Radiation Belt Generation of Light Nuclei Isotope

    Science.gov (United States)

    Galper, A. M.; Koldashov, S. V.; Leonv, A. A.; Mikhailov, V. V.

    2003-07-01

    Nuclear interactions between inner zone protons and atoms in the upper atmosphere provide the essential source of H and He isotop es nuclei in radiation belt. This paper reports the calculations of these isotop es intensities from the inner zone proton intensity model AP-8, the atmosphere drift-averaged composition and densities model MSIS-90, and cross sections for the various interaction processes. To calculate drift-averaged densities and energy losses of secondaries the particles are traced in geomagnetic field according IGRF-95 model by numerical solution of motion equation. The calculations account for nuclear interactions kinematic along the whole trapped protons trajectories. The results of calculations are compared with experimental data from SAMPEX, CRRES, RESURS-04 and MITA satellites taken during different solar activity phases. The comparison with observational data shows that the atmosphere is sufficient source for inner zone 4 He, 3 He,2 H and 3 H for L-shell less than 1.3.

  10. Isotopic signatures: An important tool in today`s world

    Energy Technology Data Exchange (ETDEWEB)

    Rokop, D.J.; Efurd, D.W.; Benjamin, T.M.; Cappis, J.H.; Chamberlin, J.W.; Poths, H.; Roensch, F.R.

    1995-12-01

    High-sensitivity/high-accuracy actinide measurement techniques developed to support weapons diagnostic capabilities at the Los Alamos National Laboratory are now being used for environmental monitoring. The measurement techniques used are Thermal Ionization Mass Spectrometry (TIMS), Alpha Spectrometry(AS), and High Resolution Gamma Spectrometry(HRGS). These techniques are used to address a wide variety of actinide inventory issues: Environmental surveillance, site characterizations, food chain member determination, sedimentary records of activities, and treaty compliance concerns. As little as 10 femtograms of plutonium can be detected in samples and isotopic signatures determined on samples containing sub-100 femtogram amounts. Uranium, present in all environmental samples, can generally yield isotopic signatures of anthropogenic origin when present at the 40 picogam/gram level. Solid samples (soils, sediments, fauna, and tissue) can range from a few particles to several kilograms in size. Water samples can range from a few milliliters to as much as 200 liters.

  11. $\\beta$-NMR of copper isotopes in ionic liquids

    CERN Multimedia

    We propose to test the feasibility of spin-polarization and $\\beta$-NMR studies on several short-lived copper isotopes, $^{58}$ Cu, $^{74}$Cu and $^{75}$Cu in crystals and liquids. The motivation is given by biological studies of Cu with $\\beta$-NMR in liquid samples, since Cu is present in a large number of enzymes involved in electron transfer and activation of oxygen. The technique is based on spin-polarization via optical pumping in the new VITO beamline. We will use the existing lasers, NMR magnet and NMR chambers and we will prepare a new optical pumping system. The studies will be devoted to tests of achieved $\\beta$-asymmetry in solid hosts, the behaviour of asymmetry when increasing vacuum, and finally NMR scans in ionic liquids. The achieved spin polarization will be also relevant for the plans to measure with high precision the magnetic moments of neutron-rich Cu isotopes.

  12. Large Sulfur Isotope Fractionation Does Not Require Disproportionation

    Science.gov (United States)

    Sim, Min Sub; Bosak, Tanja; Ono, Shuhei

    2011-07-01

    The composition of sulfur isotopes in sedimentary sulfides and sulfates traces the sulfur cycle throughout Earth’s history. In particular, depletions of sulfur-34 (34S) in sulfide relative to sulfate exceeding 47 per mil (‰) often serve as a proxy for the disproportionation of intermediate sulfur species in addition to sulfate reduction. Here, we demonstrate that a pure, actively growing culture of a marine sulfate-reducing bacterium can deplete 34S by up to 66‰ during sulfate reduction alone and in the absence of an extracellular oxidative sulfur cycle. Therefore, similar magnitudes of sulfur isotope fractionation in sedimentary rocks do not unambiguously record the presence of other sulfur-based metabolisms or the stepwise oxygenation of Earth’s surface environment during the Proterozoic.

  13. Large sulfur isotope fractionation does not require disproportionation.

    Science.gov (United States)

    Sim, Min Sub; Bosak, Tanja; Ono, Shuhei

    2011-07-01

    The composition of sulfur isotopes in sedimentary sulfides and sulfates traces the sulfur cycle throughout Earth's history. In particular, depletions of sulfur-34 ((34)S) in sulfide relative to sulfate exceeding 47 per mil (‰) often serve as a proxy for the disproportionation of intermediate sulfur species in addition to sulfate reduction. Here, we demonstrate that a pure, actively growing culture of a marine sulfate-reducing bacterium can deplete (34)S by up to 66‰ during sulfate reduction alone and in the absence of an extracellular oxidative sulfur cycle. Therefore, similar magnitudes of sulfur isotope fractionation in sedimentary rocks do not unambiguously record the presence of other sulfur-based metabolisms or the stepwise oxygenation of Earth's surface environment during the Proterozoic.

  14. Manus Water Isotope Investigation Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Conroy, Jessica L [University of Illinois, Urbana-Champaign; Cobb, Kim M [Georgia Institute of Technology; Noone, David [University of Colorado, Boulder

    2016-03-01

    The objective of this field campaign was to investigate climatic controls on the stable isotopic composition of water vapor, precipitation, and seawater in the western tropical Pacific. Simultaneous measurements of the stable isotopic composition of vapor and precipitation from April 28 to May 8, 2013, at the Manus Tropical Western Pacific Atmospheric Radiation Measurement site, provided several key insights into the nature of the climate signal archived in precipitation and vapor isotope ratios. We observed a large shift from lower to higher isotopic values in vapor and precipitation because of the passage of a mesoscale convective system west of the site and a transition from a regional stormy period into a more quiescent period. During the quiescent period, the stable isotopic composition of vapor and precipitation indicated the predominance of oceanic evaporation in determining the isotopic composition of boundary-layer vapor and local precipitation. There was not a consistent relationship between intra-event precipitation amount at the site and the stable isotopic composition of precipitation, thus challenging simplified assumptions about the isotopic “amount effect” in the tropics on the time scale of individual storms. However, some storms did show an amount effect, and deuterium excess values in precipitation had a significant relationship with several meteorological variables, including precipitation, temperature, relative humidity, and cloud base height across all measured storms. The direction of these relationships points to condensation controls on precipitation deuterium excess values on intra-event time scales. The relationship between simultaneous measurements of vapor and precipitation isotope ratios during precipitation events indicates the ratio of precipitation-to-vapor isotope ratios can diagnose precipitation originating from a vapor source unique from boundary-layer vapor and rain re-evaporation.

  15. Lead Isotopes in Highway Runoff

    Science.gov (United States)

    Ferreira, M.; Lau, S.; Green, P. G.; Stenstrom, M. K.

    2011-12-01

    Lead (Pb) isotopes have been used extensively to study the provenance of lead pollution on air, water, and sediments. In this study, we measured Pb isotopes and Pb aqueous concentration in highway runoff in three west Los Angeles sites. Those three sites, part of a long-term study sponsored by the California Department of Transportation, represent small catchment areas, and host heavy traffic. In addition, there were no inputs of sand or salt to the highway because the sites are almost completely impervious and also due to the lack of snow to be controlled. Highway runoff from the three sites was collected for 7 storms during the 2004-2005 Winter. Grab samples were collected every 15 minutes during the first hour, and hourly afterwards. A total of 202 samples were collected and filtered into five size fractions (100μm). Aqueous concentration of Pb range from 0.08μg/L to 46.95μg/L (7.98±10.89μg/L) and it is not correlated with any of the lead isotope ratios. The 208Pb/206Pb ratio ranges from 1.983 to 2.075 (2.024±0.026) and there is no statistical difference for the mean value of the 208Pb/206Pb ratio for the four particulate size fractions (0.45-8μm, 8-20μm, 20-100μm, >100μm). However, the 208Pb/206Pb ratio of nearby soils yield 2.060±0.021 and it is statistically different from the ratios obtained for the highway runoff. This hints that the lead present in highway runoff does not come from local soils. The 207Pb/206Pb ratio ranges from 0.804 to 0.847 (0.827±0.011) and there is no statistical difference for the mean value of the 207Pb/206Pb ratio for the four particulate size fractions (0.45-8μm, 8-20μm, 20-100μm, >100μm). Surprisingly, there is also no statistical difference with the 207Pb/206Pb ratio of nearby soils (0.833±0.009).

  16. Late Holocene Human Activity Inferred from Sedimentary n-Alkanes and Their Carbon Isotope in the Huguangyan Maar Lake%湖光岩玛珥湖晚全新世人类活动的叶蜡烷烃及其碳同位素沉积记录

    Institute of Scientific and Technical Information of China (English)

    柏杨; 欧阳婷萍; 贾国东

    2014-01-01

    通过对广东省湛江市湖光岩玛珥湖晚全新世沉积物中叶蜡烷烃(n-C29,n-C31,n-C33)及其碳同位素(δ13C)进行分析,探讨该湖区约3.5 ka BP以来的植被变化历史,重点讨论了人类活动对该区域植被变化可能带来的影响。叶蜡烷烃δ13C在1.7 ka BP以前偏轻,例如长链烷烃碳同位素在1.78 ka BP为-33.27‰,表明湖区C3植物占绝对优势,表现为典型的C3型生态系统;在1.7 ka BP之后碳同位素明显快速偏重,在1.63 ka BP为-28.26‰,指示了C4植物出现和C4比例上升的过程。C4植物的出现通常指示气候的干旱化,但是烷烃Paq和ACL指数(平均链长)则显示湖区气候可能在1.7 ka BP后变湿润。通过与研究区甘蔗的同位素和ACL指数的比较分析,推测这一矛盾现象可能与湖区开始有一定规模的甘蔗种植活动有关。%In this study, late Holocene sedimentary records of leaf wax n-alkanes and theirδ13 C from Huguangyan Maar Lake (H.M.L) in Zhanjiang, Guangdong Province, were used to reconstruct the vegetation variations as well as human activities in the lake catchment over the past 3500 years. Carbon isotopic compositions (δ13C) of leaf wax n-alkanes (n-C29, n-C31 and n-C33) were predominantly lighter than-32‰before 1.7 ka BP, suggesting that a typically pure C3 ecosystem might exist before 1.7 ka BP; for example, carbon isotope average value of long-chain n-alkanes was -33.27 ‰ in 1.78 ka BP; after that δ13C values increased rapidly and significantly, carbon isotope value was-28.26‰in 1.63 ka BP, indicating the emergence and increase of C4 plants. C4 plants usually indicate an arid climate, however, the n-alkanes indices that both increased Paq and reduced ACL indicate a humid climate after 1.7 ka BP. This contradiction can be well explained by invoking anthropogenic sugarcane plantation in the catchment at 1.7 ka BP. Furthermore, when it comes to the isotope change of samples, we find

  17. 77 FR 14837 - Advisory Committee on the Medical Uses of Isotopes: Meeting Notice

    Science.gov (United States)

    2012-03-13

    ... Medical Uses of Isotopes (ACMUI) on April 16-17, 2012. A sample of agenda items to be discussed during the...) regulations; (3) medical-related events from fiscal year 2011; (4) an update on proposed regulatory changes... perspectives; and (9) half-life activity as a function of solar activity. The agenda is subject to change....

  18. Identification of triclosan-degrading bacteria using stable isotope probing, fluorescence in situ hybridization and microautoradiography

    DEFF Research Database (Denmark)

    Lolas, Ihab Bishara Lolas; Chen, Xijuan; Bester, Kai

    2012-01-01

    -based stable isotope probing (DNA-SIP) combined with microautoradiography-fluorescence in situ hybridization (MAR-FISH) was applied to identify active triclosan degraders in an enrichment culture inoculated with activated sludge. Clone library sequences of 16S rRNA genes derived from the heavy DNA fractions...

  19. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    composition of contemporaneous seawater. Marine carbonates are ubiquitous throughout Earth’s rock record rendering them a particularly interesting archive for constraining past changes in ocean chemistry. This thesis includes an investigation of the fractionation behavior of Cr isotopesduring coprecipitation......Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past...... related to the rise of oxygen and the evolution of the biosphere. However, before the Cr isotopesystem can be applied to faithfully delineate paleo-environmental changes, careful assessment of the signal robustness and a thorough understanding of the Cr cycle in Earth system processes is necessary...

  20. Measurement of isotope abundance variations in nature by gravimetric spiking isotope dilution analysis (GS-IDA).

    Science.gov (United States)

    Chew, Gina; Walczyk, Thomas

    2013-04-02

    Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

  1. Calculation of the inventory and near-field release rates of radioactivity from neutron-activated metal parts discharged from the high flux isotope reactor and emplaced in solid waste storage area 6 at Oak Ridge National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Kelmers, A.D.; Hightower, J.R.

    1987-05-01

    Emplacement of contaminated reactor components involves disposal in lined and unlined auger holes in soil above the water table. The radionuclide inventory of disposed components was calculated. Information on the composition and weight of the components, as well as reasonable assumptions for the neutron flux fueling use, the time of neutron exposure, and radioactive decay after discharge, were employed in the inventory calculation. Near-field release rates of /sup 152/Eu, /sup 154/Eu, and /sup 155/Eu from control plates and cylinders were calculated for 50 years after emplacement. Release rates of the europium isotopes were uncertain. Two release-rate-limiting models were considered and a range of reasonable values were assumed for the time-to-failure of the auger-hole linear and aluminum cladding and europium solubility in SWSA-6 groundwater. The bounding europium radionuclide near-field release rates peaked at about 1.3 Ci/year total for /sup 152,154,155/Eu in 1987 for the lower bound, and at about 420 Ci/year in 1992 for the upper bound. The near-field release rates of /sup 55/Fe, /sup 59/Ni, /sup 60/Co, and /sup 63/Ni from stainless steel and cobalt alloy components, as well as of /sup 10/Be, /sup 41/Ca, and /sup 55/Fe from beryllium reflectors, were calculated for the next 100 years, assuming bulk waste corrosion was the release-rate-limiting step. Under the most conservative assumptions for the reflectors, the current (1986) total radionuclide release rate was calculated to be about 1.2 x 10/sup -4/ Ci/year, decreasing by 1992 to a steady release of about 1.5 x 10/sup -5/ Ci/year due primarily to /sup 41/Ca. 50 refs., 13 figs., 8 tabs.

  2. High sulfur isotope fractionation associated with anaerobic oxidation of methane in a low sulfate, iron rich environment

    Directory of Open Access Journals (Sweden)

    Hannah Sophia Weber

    2016-06-01

    Full Text Available Sulfur isotope signatures provide key information for the study of microbial activity in modern systems and the evolution of the Earth surface redox system. Microbial sulfate reducers shift sulfur isotope distributions by discriminating against heavier isotopes. This discrimination is strain-specific and often suppressed at sulfate concentrations in the lower micromolar range that are typical to freshwater systems and inferred for ancient oceans. Anaerobic oxidation of methane (AOM is a sulfate-reducing microbial process with a strong impact on global sulfur cycling in modern habitats and potentially in the geological past, but its impact on sulfur isotope signatures is poorly understood, especially in low sulfate environments. We investigated sulfur cycling and 34S fractionation in a low-sulfate freshwater sediment with biogeochemical conditions analogous to Early Earth environments. The zone of highest AOM activity was associated in situ with a zone of strong 34S depletions in the pool of reduced sulfur species, indicating a coupling of sulfate reduction and AOM at sulfate concentrations < 50 µmol L-1. In slurry incubations of AOM-active sediment, the addition of methane stimulated sulfate reduction and induced a bulk sulfur isotope effect of ~29 ‰. Our results imply that sulfur isotope signatures may be strongly impacted by AOM even at sulfate concentrations two orders of magnitude lower than at present oceanic levels. Therefore, we suggest that sulfur isotope fractionation during AOM must be considered when interpreting 34S signatures in modern and ancient environment.

  3. The isotope effect: Prediction, discussion, and discovery

    CERN Document Server

    Kragh, Helge

    2011-01-01

    The precise position of a spectral line emitted by an atomic system depends on the mass of the atomic nucleus and is therefore different for isotopes belonging to the same element. The possible presence of an isotope effect followed from Bohr's atomic theory of 1913, but it took several years before it was confirmed experimentally. Its early history involves the childhood not only of the quantum atom, but also of the concept of isotopy. Bohr's prediction of the isotope effect was apparently at odds with early attempts to distinguish between isotopes by means of their optical spectra. However, in 1920 the effect was discovered in HCl molecules, which gave rise to a fruitful development in molecular spectroscopy. The first detection of an atomic isotope effect was no less important, as it was by this means that the heavy hydrogen isotope deuterium was discovered in 1932. The early development of isotope spectroscopy illustrates the complex relationship between theory and experiment, and is also instructive with...

  4. Compound specific isotope analysis of organophosphorus pesticides.

    Science.gov (United States)

    Wu, Langping; Yao, Jun; Trebse, Polonca; Zhang, Ning; Richnow, Hans H

    2014-09-01

    Compound-specific isotope analysis (CSIA) has been established as a tool to study the environmental fate of a wide range of contaminants. In this study, CSIA was developed to analyse the stable carbon isotope signatures of the widely used organophosphorus pesticides: dichlorvos, omethoate and dimethoate. The linearity of the GC-C-IRMS system was tested for target pesticides and led to an acceptable isotope composition within the uncertainty of the instrument. In order to assess the accuracy of the developed method, the effect of the evaporation procedure on measured carbon isotope composition (δ(13)C) values was studied and showed that concentration by evaporation of solvents had no significant isotope effect. The CSIA was then applied to investigate isotope fractionation of the hydrolysis and photolysis of selected pesticides. The carbon isotope fractionation of tested pesticides was quantified by the Rayleigh model, which revealed a bulk enrichment factor (ε) of -0.2±0.1‰ for hydrolysis of dichlorvos, -1.0±0.1‰ and -3.7±1.1‰ for hydrolysis and photolysis of dimethoate respectively. This study is a first step towards the application of CSIA to trace the transport and degradation of organophosphorus pesticides in the environment.

  5. Si isotope homogeneity of the solar nebula

    Energy Technology Data Exchange (ETDEWEB)

    Pringle, Emily A.; Savage, Paul S.; Moynier, Frédéric [Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130 (United States); Jackson, Matthew G. [Department of Earth Science, University of California, Santa Barbara, CA 93109 (United States); Barrat, Jean-Alix, E-mail: eapringle@wustl.edu, E-mail: savage@levee.wustl.edu, E-mail: pringle@ipgp.fr, E-mail: moynier@ipgp.fr, E-mail: jackson@geol.ucsb.edu, E-mail: Jean-Alix.Barrat@univ-brest.fr [Université Européenne de Bretagne, Université de Brest, CNRS UMR 6538 (Domaines Océaniques), I.U.E.M., Place Nicolas Copernic, F-29280 Plouzané Cedex (France)

    2013-12-20

    The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in {sup 29}Si/{sup 28}Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of {sup 29}Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the calcium-aluminum-rich inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

  6. Stable isotopic characterisation of francolite formation

    Science.gov (United States)

    McArthur, J. M.; Benmore, R. A.; Coleman, M. L.; Soldi, C.; Yeh, H.-W.; O'Brien, G. W.

    1986-02-01

    Stable isotopic data are presented for 112 samples of francolite from 18 separate phosphate deposits. Values of δ 13C and δ 34S in most offshore deposits suggest formation within oxic or suboxic environments either by carbonate replacement or direct precipitation of francolite from water of normal marine compositions. The exceptions are concretionary francolite from Namibia, which has an isotopic composition in keeping with its formation within organic-rich sediments, and that from offshore Morocco, which has an isotopic signature of the anoxic/suboxic interface. Onshore deposits from Jordan, Mexico, South Africa and, possibly, the Permian Phosphoria Formation in the western U.S.A., are substantially depleted in 18O: they appear to be too altered for deductions to be made about their environments of formation. In other onshore deposits which are unaltered, or minimally altered, the isotopic composition suggests that some formed within sulphate-reducing sediments (Sedhura, Morocco) whilst francolite from the Georgina Basin of Australia formed at the oxic/anoxic boundary, where oxidation of biogenic H 2S decreases the δ 34S of pore water. In general, pelletal samples show non-oxic isotopic signatures, whilst non-pelletal samples show oxic isotopic signatures, but samples from Namibia, Peru (Ica Plateau) and the Californian and Moroccan margins are exceptions to this rule. Morphology may therefore be a misleading indicator of francolite genesis as no definitive relation exists between phosphorite type and isotopic signature.

  7. Stable isotope composition of land snail body water and its relation to environmental waters and shell carbonate

    Science.gov (United States)

    Goodfriend, Glenn A.; Magaritz, Mordeckai; Gat, Joel R.

    1989-12-01

    Day-to-day and within-day (diel) variations in δD and δ18O of the body water of the land snail, Theba pisana, were studied at a site in the southern coastal plain of Israel. Three phases of variation, which relate to isotopic changes in atmospheric water vapor, were distinguished: 1) on rain days, snail water becomes isotopically depleted approximately in the direction of the rain isotope values, but always less depleted in D as is atmospheric water vapor; 2) during the 1-3 days following a rain, the snail water becomes isotopically enriched along a line with slope persists until the next rain event. The isotopic variations can be explained by isotopic equilibration with atmospheric water vapor and/or uptake of dew derived therefrom. During the winter, when the snails are active, there is only very minor enrichment in 18O relative to equilibrium with water vapor or dew, apparently as a result of metabolic activity. But this enrichment becomes pronounced after long periods of inactivity. Within-day variation in body water isotopic composition is minor on non-rain days. Shell carbonate is enriched in 18O by ca. 1-2%. relative to equilibrium with body water. In most regions, the isotopic composition of atmospheric water vapor (or dew) is a direct function of that of rain. Because the isotopic composition of snail body water is related to that of atmospheric water vapor and the isotopic composition of shell carbonate in turn is related to that of body water, land snail shell carbonate 18O should provide a reliable indication of rainfall 18O. However, local environmental conditions and the ecological properties of the snail species must be taken into account.

  8. Beneficial uses and production of isotopes

    CERN Document Server

    2001-01-01

    Isotopes, radioactive and stable, are used worldwide in various applications related to medical diagnosis or care, industry and scientific research. More than fifty countries have isotope production or separation facilities operated for domestic supply, and sometimes for international markets. This publication provides up-to-date information on the current status of, and trends in, isotope uses and production. It also presents key issues, conclusions and recommendations, which will be of interest to policy makers in governmental bodies, scientists and industrial actors in the field.

  9. The Facility for Rare Isotope Beams

    Directory of Open Access Journals (Sweden)

    Wrede C.

    2015-01-01

    Full Text Available The Facility for Rare Isotope Beams (FRIB is a United States Department of Energy user facility currently under construction on the campus of Michigan State University. Based on a 400 kW, 200 MeV/u heavy-ion driver linac, FRIB will deliver high-quality fast, thermalized, and re-accelerated beams of rare isotopes with unprecedented intensities to a variety of experimental areas and equipment. New science opportunities at the frontiers of nuclear structure, nuclear astrophysics, fundamental symmetries, and societal applications will be enabled by this future world-leading rare-isotope beam facility.

  10. The Facility for Rare Isotope Beams

    Science.gov (United States)

    Wrede, C.

    2015-05-01

    The Facility for Rare Isotope Beams (FRIB) is a United States Department of Energy user facility currently under construction on the campus of Michigan State University. Based on a 400 kW, 200 MeV/u heavy-ion driver linac, FRIB will deliver high-quality fast, thermalized, and re-accelerated beams of rare isotopes with unprecedented intensities to a variety of experimental areas and equipment. New science opportunities at the frontiers of nuclear structure, nuclear astrophysics, fundamental symmetries, and societal applications will be enabled by this future world-leading rare-isotope beam facility.

  11. Isotopic Fractionation of Selenium Oxyanions in Wetlands

    Science.gov (United States)

    Clark, S. K.; Johnson, T. M.

    2004-05-01

    As oxic surface waters pass through aquatic macrophytes and over anoxic sediments in wetlands and lakes, the dissolved Se load often decreases; and, Se isotope ratio measurements can provide information about the mechanisms involved. Previous work on microbially induced isotopic fractionation of Se oxyanions under nearly natural conditions using wetland sediments shows consistent Se isotopic shifts during reduction of Se(VI) and Se(IV) to insoluble Se(0). However, previous isotopic studies of total dissolved selenium in wetlands found little to no isotopic shift as dissolved selenium concentrations decreased. This suggests that plant/algal uptake, followed by deposition and degradation, is the primary route of Se transfer into sediments. However, it is possible that the effective isotopic fractionation between Se in the surface water and Se deposited into sediments is somehow much less than the fractionation induced by the reduction reaction, or that cycling of organically bound Se is involved. In this study, we report Se isotope data for Se(VI), Se(IV) and total dissolved Se, Se(T), in surface waters from three wetland/lake sites: Sweitzer Lake, CO; 33-Mile Reservoir, WY; and, a small pond adjacent to Benton Lake, MT. We isolated Se(IV) via hydride generation, and Se(VI) via ion exchange. Se(T), including any organic components, was also analyzed. Isotope analysis was performed on an Isoprobe MC-ICPMS, using a method modified from that of Rouxel et al. (2002). We used the 82Se + 74Se double spike approach, and spiked samples before species separation. Our results for all three locations indicate similar trends in concentration changes and isotopic shifts between the inflow and outflow waters. Se(T) concentrations decrease by 45-70%, and Se(VI) concentrations decrease by 60-90%, whereas Se(IV) concentrations increase by 60-150%. Concomitant 80Se/76Se shifts are +0.5-0.8‰ for Se(T); -0.1-0.5‰ for Se(VI); and +0.4-6.5‰ for Se(IV). These data provide greater

  12. Isotope fractionation during the anaerobic consumption of acetate by methanogenic and sulfate-reducing microorganisms

    Science.gov (United States)

    Gövert, D.; Conrad, R.

    2009-04-01

    During the anaerobic degradation of organic matter in anoxic sediments and soils acetate is the most important substrate for the final step in production of CO2 and/or CH4. Sulfate-reducing bacteria (SRB) and methane-producing archaea both compete for the available acetate. Knowledge about the fractionation of 13C/12C of acetate carbon by these microbial groups is still limited. Therefore, we determined carbon isotope fractionation in different cultures of acetate-utilizing SRB (Desulfobacter postgatei, D. hydrogenophilus, Desulfobacca acetoxidans) and methanogens (Methanosarcina barkeri, M. acetivorans). Including literature values (e.g., Methanosaeta concilii), isotopic enrichment factors (epsilon) ranged between -35 and +2 permil, possibly involving equilibrium isotope effects besides kinetic isotope effects. The values of epsilon were dependent on the acetate-catabolic pathway of the particular microorganism, the methyl or carboxyl position of acetate, and the relative availability or limitation of the substrate acetate. Patterns of isotope fractionation in anoxic lake sediments and rice field soil seem to reflect the characteristics of the microorganisms actively involved in acetate catabolism. Hence, it might be possible using environmental isotopic information to determine the type of microbial metabolism converting acetate to CO2 and/or CH4.

  13. Use of the Bochum proton microprobe in isotope stratigraphy and paleoceanographic

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, F.; Bruckschen, P.; Korte, C. [Ruhr-University, Bochum (Germany). Institute fuer Geologie; Meijer, J. [Ruhr-Univ., Bochum (Germany). Inst. fuer Physik mit Ionenstrahlen; Veizer, J. [Ruhr-University Bochum (Germany). Institute fuer Geologie]|[Ottawa-Carleton Univ., Ottawa, ON (Canada)

    1998-06-01

    Over the past five years, the proton microprobe at Bochum (Germany) has been used as a trace element tool in the context of isotope stratigraphy and paleoceanographic studies. The Sr, O, and C isotopic composition of some biogenic material (e.g. calcitic brachiopod shells, phosphatic conodonts) is widely accepted to mirror, under favourable conditions, the isotopic composition of the coeval sea water. The latter, in turn, is a function of a variety of global processes, such as climatic change, volcanic activity, plate tectonics or circulation of ocean water. Thus, on the basis of the isotopic properties of fossil shell material, isotope curves can be constructed that reflect variations in the above factors over the entire Phanerozoic. However, as a consequence of the long time elapsed since deposition of the fossils, they are prone to chemical and isotopic alteration and may thus yield equivocal or even irrelevant information if no care is taken to monitor the degree of their diagenetic alteration. Trace element composition of the fossil material, combined with cathodoluminescence investigations, is one of the most frequently utilized tools to assess the diagenetic quality of the samples. Beam current was in the range of a few nA, resulting in charges of 1-10 {mu}C for a single measurement. Detection limits for point analyses were between 10 and 30 ppm for Mn, Fe, Sr, but considerably higher for rare earth elements. Accuracy around 10% for a number of elements analysed is reported. 8 refs., 2 figs.

  14. Atmospheric controls on the precipitation isotopes over the Andaman Islands, Bay of Bengal

    Science.gov (United States)

    Chakraborty, S.; Sinha, N.; Chattopadhyay, R.; Sengupta, S.; Mohan, P. M.; Datye, A.

    2016-01-01

    Isotopic analysis of precipitation over the Andaman Island, Bay of Bengal was carried out for the year 2012 and 2013 in order to study the atmospheric controls on rainwater isotopic variations. The oxygen and hydrogen isotopic compositions are typical of the tropical marine sites but show significant variations depending on the ocean-atmosphere conditions; maximum depletion was observed during the tropical cyclones. The isotopic composition of rainwater seems to be controlled by the dynamical nature of the moisture rather than the individual rain events. Precipitation isotopes undergo systematic depletions in response to the organized convection occurring over a large area and are modulated by the integrated effect of convective activities. Precipitation isotopes appear to be linked with the monsoon intraseasonal variability in addition to synoptic scale fluctuations. During the early to mid monsoon the amount effect arose primarily due to rain re-evaporation but in the later phase it was driven by moisture convergence rather than evaporation. Amount effect had distinct characteristics in these two years, which appeared to be modulated by the intraseasonal variability of monsoon. It is shown that the variable nature of amount effect limits our ability to reconstruct the past-monsoon rainfall variability on annual to sub-annual time scale. PMID:26806683

  15. Substrate and Transition State Binding in Alkaline Phosphatase Analyzed by Computation of Oxygen Isotope Effects.

    Science.gov (United States)

    Roston, Daniel; Cui, Qiang

    2016-09-14

    Enzymes are powerful catalysts, and a thorough understanding of the sources of their catalytic power will facilitate many medical and industrial applications. Here we have studied the catalytic mechanism of alkaline phosphatase (AP), which is one of the most catalytically proficient enzymes known. We have used quantum mechanics calculations and hybrid quantum mechanics/molecular mechanics (QM/MM) simulations to model a variety of isotope effects relevant to the reaction of AP. We have calculated equilibrium isotope effects (EIEs), binding isotope effects (BIEs), and kinetic isotope effects (KIEs) for a range of phosphate mono- and diester substrates. The results agree well with experimental values, but the model for the reaction's transition state (TS) differs from the original interpretation of those experiments. Our model indicates that isotope effects on binding make important contributions to measured KIEs on V/K, which complicated interpretation of the measured values. Our results provide a detailed interpretation of the measured isotope effects and make predictions that can test the proposed model. The model indicates that the substrate is deformed in the ground state (GS) of the reaction and partially resembles the TS. The highly preorganized active site preferentially binds conformations that resemble the TS and not the GS, which induces the substrate to adapt to the enzyme, rather than the other way around-as with classic "induced fit" models. The preferential stabilization of the TS over the GS is what lowers the barrier to the chemical step.

  16. Characterization of phenols biodegradation by compound specific stable isotope analysis

    Science.gov (United States)

    Wei, Xi; Gilevska, Tetyana; Wenzig, Felix; Hans, Richnow; Vogt, Carsten

    2015-04-01

    Biodegradation of phenol and alkylphenols has been described under both oxic and anoxic conditions. In the absence of molecular oxygen, the degradation of phenolic compounds is initiated by microorganisms through carboxylation, fumarate addition to the methyl moiety or anoxic hydroxylation of the methyl moiety. Comparatively, under aerobic condition, the initiation mechanisms are revealed to be monoxygenation or dihydroxylation for phenol and ring hydroxylation or methyl group oxidation for cresols. While several studies biochemically characterized the enzymes and reaction mechanisms in the relevant degradation pathways, isotope fractionation patterns were rarely reported possibly due to constraints in current analytical methods. In this study, the carbon isotope fractionation patterns upon the degradation of phenol and cresols by several strains were analyzed by using isotope ratio mass spectrometry connected with liquid chromatography (LC-IRMS). The corresponding enrichment factors for carbon (ƐC) have been obtained. Cresols degradation by various strains showed generally moderate carbon isotope fractionation patterns with notable differences. For p-cresol degradation, five strains were examined. The aerobic strain Acinetobacter calcoaceticus NCIMB8250 exploits ring hydroxylation by molecular oxygen as initial reaction, and a ƐC value of -1.4±0.2‰ was obtained. Pseudomonas pseudoalcaligenes NCIMB 9867, an aerobic strain initiating cresols degradation via oxygen-dependent side chain hydroxylation, yielded a ƐC value of -2.3±0.2‰. Under nitrate-reducing conditions, Geobacter metallireducens DSM 7210 and Azoarcus buckelii DSM 14744 attacks p-cresol at the side chain by monohydroxylation using water as oxygen source; the two strains produced ƐC values of -3.6±0.4‰ and -2±0.1‰, accordingly. The sulfate-reducing Desulfosarcina cetonica DSM 7267 activating cresols by fumarate addition to the methyl moiety yielded ƐC values of -1.9±0.2‰ for p

  17. Clumped-Isotope Thermometry and Oxygen Isotope Systematics in Speleothem Calcite From a Near Cave-Entrance Environment

    Science.gov (United States)

    Carlson, P. E.; Banner, J.; Breecker, D.; Affek, H. P.

    2015-12-01

    Speleothems that grow in well-ventilated zones of caves have not been widely used in paleoclimate studies, yet may provide paleotemperature records. These zones are characterized by low CO2 concentrations year-round and, in temperate climates, large seasonal temperature fluctuations. They are typically avoided for paleoclimate reconstruction due to concerns about kinetic isotope effects (KIE). However, speleothems in general seem to be sensitive to KIE, even in non-ventilated areas and can nonetheless provide useful paleoclimate records. At Westcave Preserve (Westcave), a shallow, well-ventilated cave in central Texas, we have found seasonal temperature differences recorded in both the oxygen isotope and clumped isotope compositions of speleothem calcite grown on glass-plate substrates harvested from active drips. Although growth rates in this cave are relatively rapid, speleothem analogs in Westcave are growing near oxygen-isotopic equilibrium with their drip waters (between the calibrations of Kim and O'Neil, 1997 and Coplen, 2007). We have tested the compatibility of the Zaarur et al. (2013) clumped isotope bulk solution thermometer calibration to glass-substrate calcite in the cave collected during various months. This technique can provide absolute temperatures, but is sensitive to kinetic isotope effects, often significantly overestimating growth temperatures of speleothems. When this thermometer was applied to calcite collected from near where the plates were impacted by drip water, it overestimated measured temperatures by 7.7 ± 4.3°C, showing moderate KIE. When applied to calcite away from the drip impact, it overestimated temperatures by 18.7 ± 4.2°C, showing KIE increasing away from the drip. Measured monthly average temperatures in the cave ranged seasonally between 8 and 28°C, and daily temperatures vary significantly. At Westcave, calcite growth rates increase with temperature, and the calcite may therefore preferentially record warmer daily or

  18. Divergence of stable isotopes in tap water across China

    Science.gov (United States)

    Zhao, Sihan; Hu, Hongchang; Tian, Fuqiang; Tie, Qiang; Wang, Lixin; Liu, Yaling; Shi, Chunxiang

    2017-03-01

    Stable isotopes in water (e.g., δ2H and δ18O) are important indicators of hydrological and ecological patterns and processes. Tap water can reflect integrated features of regional hydrological processes and human activities. China is a large country with significant meteorological and geographical variations. This report presents the first national-scale survey of Stable Isotopes in Tap Water (SITW) across China. 780 tap water samples have been collected from 95 cities across China from December 2014 to December 2015. (1) Results yielded the Tap Water Line in China is δ2H = 7.72 δ18O + 6.57 (r2 = 0.95). (2) SITW spatial distribution presents typical “continental effect”. (3) SITW seasonal variations indicate clearly regional patterns but no trends at the national level. (4) SITW can be correlated in some parts with geographic or meteorological factors. This work presents the first SITW map in China, which sets up a benchmark for further stable isotopes research across China. This is a critical step toward monitoring and investigating water resources in climate-sensitive regions, so the human-hydrological system. These findings could be used in the future to establish water management strategies at a national or regional scale.

  19. Iron isotope geochemistry in the Antarctic cryptoendolithic microbial ecosystem

    Science.gov (United States)

    Sun, H.

    2002-05-01

    The stable isotope composition of iron is a potentially powerful tracer of biogeochemical cycles because iron is ubiquitous, it is required by all organisms, and it is resistant to alterations during diagenesis. Here we report evidence of biological iron isotope fractionation in the weathering process of sandstone in McMurdo Dry Valleys, Antarctica, caused by the cryptoendolithic lichen-dominated microbial community that live below the rock surface. The fungi secrete oxalic acid, which under the sunlight reduces and dissolves the iron in the colonized zone. The mobilized iron diffuses to the rock surface and the rock interior below the organisms where it is re-oxidized. This leaching process is shown to prefer lighter isotopes of iron, leaving the colonized layer enriched in del 56Fe by as much 0.8 per mil. Had endolithic microorganisms occurred on Mars as commonly believed, they might have left similar iron biosignatures, well preserved in rocks because of the absence of subsequent aqueous activities.

  20. Simultaneous tracing of carbon and nitrogen isotopes in human cells.

    Science.gov (United States)

    Nilsson, Roland; Jain, Mohit

    2016-05-24

    Stable isotope tracing is a powerful method for interrogating metabolic enzyme activities across the metabolic network of living cells. However, most studies of mammalian cells have used (13)C-labeled tracers only and focused on reactions in central carbon metabolism. Cellular metabolism, however, involves other biologically important elements, including nitrogen, hydrogen, oxygen, phosphate and sulfur. Tracing stable isotopes of such elements may help shed light on poorly understood metabolic pathways. Here, we demonstrate the use of high-resolution mass spectrometry to simultaneously trace carbon and nitrogen metabolism in human cells cultured with (13)C- and (15)N-labeled glucose and glutamine. To facilitate interpretation of the complex isotopomer data generated, we extend current methods for metabolic flux analysis to handle multivariate mass isotopomer distributions (MMIDs). We find that observed MMIDs are broadly consistent with known biochemical pathways. Whereas measured (13)C MIDs were informative for central carbon metabolism, (15)N isotopes provided evidence for nitrogen-carrying reactions in amino acid and nucleotide metabolism. This computational and experimental methodology expands the scope of metabolic flux analysis beyond carbon metabolism, and may prove important to understanding metabolic phenotypes in health and disease.

  1. On the isotopic composition of magmatic carbon in SNC meteorites

    Science.gov (United States)

    Wright, I. P.; Grady, M. M.; Pillinger, C. T.

    1992-01-01

    SNC meteorites are thought, from many lines of evidence, to come from Mars. A line of investigation which has been pursued in our laboratory over the years involves measurement of the stable isotopic composition of carbon, in its various forms, in SNC meteorites. In order to establish a firm basis for studying the isotopic systematics of carbon in the martian surface environment, it is first necessary to try and constrain the delta C-13 of bulk Mars. Taking all of the available information, it would seem that the delta C-13 of the Earth's mantle lies somewhere in the range of -5 to -7 percent. Preliminary assessment of magnetic carbon in SNC meteorites, would tend to suggest a delta C-13 of 20 to 30 percent, which is conspicuously different from that of the terrestrial mantle. It is not obvious why there should be such a difference between the two planets, although many explanations are possible. One of these possibilities, that previous delta C-13 measurements for magnetic carbon in SNC meteorites are in error to some degree, is being actively investigated. The most recent results seem to constrain the theta C-13 of the magnetic carbon in SNC meteorites to about -20 percent, which is not at odds with previous estimates. As such, it is considered that a detailed investigation of the carbon isotopic systematics of martian surface materials does have the necessary information with which to proceed.

  2. Isotope effects of hafnium in solvent extraction using crown ethers

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Toshiyuki; Moriyama, Hirotake [Research Reactor Institute, Kyoto University, Osaka (Japan); Hirata, Takafumi [Laboratory for Planetary Sciences, Tokyo Institute of Technology, Tokyo (Japan); Nishizawa, Kazushige [Department of Nuclear Engineering, Graduate School of Engineering, Osaka University, Osaka (Japan)

    2001-06-01

    Hafnium isotopes were fractionated in a liquid-liquid extraction system by using seven types of crown ethers, tributyl phosphate, or {omicron}-diethoxybenzene. The largest isotope effect was observed in the isotope pair of {sup 177}Hf-{sup 179}Hf with dibenzo-24-crown-8; the isotope enrichment factor was observed to be 0.0129{+-}0.0032. (author)

  3. Environmental geochemistry of calcium isotopes: Applications of a new stable isotope approach

    Institute of Scientific and Technical Information of China (English)

    LIU Zhanmin; LIU Congqiang; HAN Guilin; WANG Zhongliang; XUE Zichen; SONG Zhaoliang; YANG Cheng

    2006-01-01

    This paper summarizes isotope fractionation mechanism, analytical method and applications in environmental geochemistry of calcium isotopes. Calcium isotopic composition can be used to constrain material sources and study geological and environmental processes as the isotopic composition of calcium (δ 44Ca) and fractionation processes depend on geochemical circumstances in nature. Recently, thanks to current advances in analytical technology of calcium isotopes, calcium isotopes are broadly used in biological and geochemical studies, such as the mechanism of plants imbibing nutrients through their roots, calcium transport in the environmental ecosystem, calcium cycle in oceans and paleo-oceans and paleo-climate. The elementary data show that δ44Ca values vary from -2.88‰ to 0.92‰ in natural samples.

  4. Newtonian kinetic isotope effects. Observation, prediction, and origin of heavy-atom dynamic isotope effects.

    Science.gov (United States)

    Kelly, Kelmara K; Hirschi, Jennifer S; Singleton, Daniel A

    2009-06-24

    Intramolecular (13)C kinetic isotope effects were determined for the dimerization of cyclopentadiene. Substantial isotope effects were observed in three positions, despite the C(2) symmetry of the cycloaddition transition state and the absence of dynamical bottlenecks after this transition state. The observed isotope effects were predicted well from trajectory studies by extrapolating the outcomes of trajectories incorporating superheavy isotopes of carbon, ranging from (20)C to (140)C. Trajectory studies suggest that the isotope effects are unrelated to zero-point energy or the geometrical and momentum properties of the transition state. However, steepest-descent paths in mass-weighted coordinates correctly predict the direction of the isotope effects, supporting a novel origin in Newton's second law of motion.

  5. Isotope effects on desorption kinetics of hydrogen isotopes implanted into stainless steel by glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, M.; Kondo, M.; Noda, N. [Hydrogen Isotope Research Center, University of Toyama, Gofuku, Toyama (Japan); Tanaka, M.; Nishimura, K. [National Institute for Fusion Science, Toki-shi, Gifu (Japan)

    2015-03-15

    In a fusion device the control of fuel particles implies to know the desorption rate of hydrogen isotopes by the plasma-facing materials. In this paper desorption kinetics of hydrogen isotopes implanted into type 316L stainless steel by glow discharge have been studied by experiment and numerical calculation. The temperature of a maximum desorption rate depends on glow discharge time and heating rate. Desorption spectra observed under various experimental conditions have been successfully reproduced by numerical simulations that are based on a diffusion-limited process. It is suggested, therefore, that desorption rate of a hydrogen isotope implanted into the stainless steel is limited by a diffusion process of hydrogen isotope atoms in bulk. Furthermore, small isotope effects were observed for the diffusion process of hydrogen isotope atoms. (authors)

  6. Tracing contamination sources in soils with Cu and Zn isotopic ratios.

    Science.gov (United States)

    Fekiacova, Z; Cornu, S; Pichat, S

    2015-06-01

    Copper (Cu) and zinc (Zn) are naturally present and ubiquitous in soils and are important micronutrients. Human activities contribute to the input of these metals to soils in different chemical forms, which can sometimes reach a toxic level for soil organisms and plants. Isotopic signatures could be used to trace sources of anthropogenic Cu and Zn pollution. The aim of this paper is to determine whether it is possible to identify (i) Cu and Zn contamination in soils and their sources, on the basis of their isotopic signatures, and (ii) situations that are a priori favorable or not for tracing Cu and Zn pollution using the isotopic approach. Therefore, we compiled data from the literature on Cu and Zn isotopes in soils, rocks and pollutants and added to this database the results of our own research. As only a few studies have dealt with agricultural contamination, we also studied a soil toposequence from Brittany, France, that experienced spreading of pig slurry for tens of years. In the surface horizons of the natural soils, the δ(65)Cu values vary from -0.15 to 0.44‰ and the δ(66)Zn from -0.03 to 0.43‰. Furthermore, vertical variations along soil profiles range from -0.95 to 0.44‰ for δ(65)Cu and from -0.53 to 0.64‰ for δ(66)Zn values. We concluded that pedogenetic processes can produce isotopic fractionation, yet, it is not always discernible and can be overprinted by an exogenous isotopic signature. Furthermore, some contaminants are enriched in heavy Cu or in light Zn compared to the rock or soil, but no generalization can be made. The anthropogenic inputs can be identified based on stable Cu and Zn isotope ratios if the isotope ratios of the sources are different from those of the soil, which needs to be tested for each individual case.

  7. Comparison of element and isotope diffusion of K and Ca in multicomponent silicate melts

    Science.gov (United States)

    van der Laan, Sieger; Zhang, Youxue; Kennedy, Allen K.; Wyllie, Peter J.

    1994-05-01

    Recent experimental work has shown that the homogenization of elemental concentrations can be much slower than that of isotopic ratios when there are strong concentration gradients in SiO 2 and Al 2O 3. The ramifications of this result for magma homogenization and other petrological problems related to diffusion are significant. We report here a comparison of experimental profiles of elemental concentrations and isotopic fractions of K and Ca in rhyolite-andesite (large concentration gradients) and rhyolite-rhyolite (small concentration gradients) melt couples. When the concentration profile and the isotopic profile of the same element in a single couple are compared, the former is much shorter than the latter in the rhyolite-andesite couple, consistent with other recent studies. However, the lengths of both concentration and isotopic profiles are similar in the rhyolite-rhyolite couple. Therefore, diffusion of an element or oxide may be decoupled from or coupled with isotopic 'diffusion', depending on whether large concentration gradients of major components are present. When the two couples are compared, the intrinsic effective binary diffusivities obtained from isotopic profiles are similar for each element in the two couples, whereas the effective binary diffusivity of K obtained from the concentration profile in the rhyolite-rhyolite couple is 37 times that in the rhyolite-andesite couple. Therefore, isotopic homogenization is roughly independent of elemental homogenization and the presence of SiO 2, Al 2O 3, and other concentration gradients, whereas elemental homogenization is strongly affected by concentration gradients. Our experimental data (isotopic and concentration profiles including uphill diffusion profiles) can be modeled quantitatively to a good approximation using a modified effective binary diffusion model in which the flux of a component is assumed to be proportional to its activity gradient instead of its concentration gradient. Therefore, the

  8. Shear heating and clumped isotope reordering in carbonate faults

    Science.gov (United States)

    Siman-Tov, Shalev; Affek, Hagit P.; Matthews, Alan; Aharonov, Einat; Reches, Ze'ev

    2016-07-01

    Natural faults are expected to heat rapidly during seismic slip and to cool quite quickly after the slip event. Here we examine clumped isotope thermometry for its ability to identify such short duration elevated temperature events along frictionally heated carbonate faults. Our approach is based on measured Δ47 values that reflect the distribution of oxygen and carbon isotopes in the calcite lattice, measuring the abundance of 13Csbnd 18O bonds, which is affected by temperature. We examine three types of calcite rock samples: (1) crushed limestone grains that were rapidly heated and then cooled in static laboratory experiments, simulating the temperature cycle experienced by fault rock during an earthquake slip; (2) limestone samples that were experimentally sheared to simulate earthquake slip events; and (3) samples from Fault Mirrors (FMs) collected from principle slip surfaces of three natural carbonate faults. Extensive FM surfaces are believed to form during earthquake slip. Our experimental results show that Δ47 values decrease rapidly (in the course of seconds) with increasing temperature and shear velocity. On the other hand, carbonate shear zones from natural faults do not show such Δ47 decrease. We suggest that the Δ47 response may be controlled by nano-size grains, the high abundance of defects, and highly stressed/strained grain boundaries within the carbonate fault zone that can reduce the activation energy for diffusion, and thus lead to an increased rate of isotopic disordering during shear experiments. In our laboratory experiments the high stress and strain on grain contacts and the presence of nanograins thus allows for rapid disordering so that a change in Δ47 occurs in a very short and relatively low intensity heating events. In natural faults it may also lead to isotopic ordering after the cessation of frictional heating thus erasing the high temperature signature of Δ47.

  9. New Mexico Center for Isotopes in Medicine

    Energy Technology Data Exchange (ETDEWEB)

    Burchiel, Scott W.

    2012-12-13

    The purpose of the New Mexico Center for Isotopes in Medicine (NMCIM) is to support research, education and service missions of the UNM College of Pharmacy Radiopharmaceutical Sciences Program (COP RSP) and the Cancer Research and Treatment Center (CRTC). NMCIM developed and coordinated unique translational research in cancer radioimaging and radiotherapy agents based on novel molecules developed at UNM and elsewhere. NMCIM was the primary interface for novel radioisotopes and radiochemistries developed at the Los Alamos National Laboratory (LANL) for SPECT/PET imaging and therapy. NMCIM coordinated the use of the small animal imaging facility with the CRTC provided support services to assist investigators in their studies. NMCIM developed education and training programs that benefited professional, graduate, and postdoctoral students that utilized its unique facilities and technologies. UNM COP RSP has been active in writing research and training grants, as well as supporting contract research with industrial partners. The ultimate goal of NMCIM is to bring new radiopharmaceutical imaging and therapeutic agents into clinical trials that will benefit the health and well being of cancer and other patients in New Mexico and the U.S.

  10. [Aseptic meningitis after isotope cisternography. 2 Cases].

    Science.gov (United States)

    Guy, G; Comoy, J; Chevet, D; Thomas, R; le Pogamp, P

    1976-01-01

    In these two patients, as in 13 others described in the literature, a typical meningitic syndrome with excitement, confusion and a fever of 104degrees F (40degrees C) appeared 4-6 hours following the intra-thecal injection. Subsequent lumbar puncture usually reveals a cloudy C.S.F. under increased pressure. The polymorphs and proteins are increased but the glucose remains normal. There are no bacteria either on direct examination or after culture. All the patients receive antibiotics. After a course of three days, the symptoms and the fever have disappeared and the C.S.F. became normal. Bacterial contamination can be ruled out. The relative roles of iodine, radio-acitivity itself, albumine and of the radio-active element which are only used for this radiotracer are discussed. The tracer contains neither stabilizer nor pH buffer. One must presume that the syndrome is due to a direct toxic action rather than to an immunological or allergic reaction. Furthermore, it is of interest that similar reactions, without infection, are seen after spinal anaesthesia and intra-thecal injection of such differing substances such as iodine contrast media, gamma globulins, other isotopes or toxic substances (Lysol) (111In-DTPA).

  11. Short course on St-02 applications of isotope dilutions and isotopic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Miller, P.

    1998-01-05

    This short course includes information on these topics and subtopics: (I) Nuclear Properties: (A) Historic roots; (B) Nomenclature; (C) Nuclear Stability and abundance; (D) Uses of isotopic techniques; (II) Instrumentation: (A) Sources; (B) Mass resolving elements; (C) Detectors; (III) Making Isotopic Measurements by ICP-MS: (A) Deadtime Correction; (B) Mass Discrimination; (C) Signal /Noise considerations; (IV) Applications and examples: (A) Isotope dilution; (B) Double Spike; (C) Biological Application; (D) Environmental Application; (E) Geological.

  12. Lead isotope studies of the Guerrero composite terrane, west-central Mexico: implications for ore genesis

    Science.gov (United States)

    Potra, Adriana; Macfarlane, Andrew W.

    2014-01-01

    field defined by the Huetamo Sequence, suggesting that these ores may also contain metals from the sedimentary rocks. The Pb isotope ratios of ore samples from the Zimapan deposit (206Pb/204Pb = 18.771-18.848) are substantially higher than the whole-rock Pb isotope compositions of the basement rocks. The similarity of ore Pb to igneous rock Pb in the Zimapan district (206Pb/204Pb = 18.800-18.968) may indicate that the proximal source of ore metals in the hydrothermal system was the igneous activity.

  13. In Vivo Mass-independent Fractionation of Mercury Isotopes in Fish

    Science.gov (United States)

    Das, R.; Odom, L. A.

    2008-12-01

    hyperfine coupling influence radical recombination and thus reaction kinetics. There is experimental evidence that this can occur during the inhibiting activity of methylmercury on creatine kinase. Here the enzyme provides the free radicals. Previously, reports of chemical mass- independent fractionation of isotopes in nature have involved gas phase reactions and largely explained by photolysis. It now seems that isotopic MIF can occur during metabolic processes as well.

  14. Tracing contamination sources in soils with Cu and Zn isotopic ratios

    Energy Technology Data Exchange (ETDEWEB)

    Fekiacova, Z.; Cornu, S. [INRA, UR 1119 Géochimie des Sols et des Eaux, F-13100 Aix en Provence (France); Pichat, S. [Laboratoire de Géologie de Lyon (LGL-TPE), Ecole Normale Supérieure de Lyon, CNRS, UMR 5276, 69007 Lyon (France)

    2015-06-01

    Copper (Cu) and zinc (Zn) are naturally present and ubiquitous in soils and are important micronutrients. Human activities contribute to the input of these metals to soils in different chemical forms, which can sometimes reach a toxic level for soil organisms and plants. Isotopic signatures could be used to trace sources of anthropogenic Cu and Zn pollution. The aim of this paper is to determine whether it is possible to identify (i) Cu and Zn contamination in soils and their sources, on the basis of their isotopic signatures, and (ii) situations that are a priori favorable or not for tracing Cu and Zn pollution using the isotopic approach. Therefore, we compiled data from the literature on Cu and Zn isotopes in soils, rocks and pollutants and added to this database the results of our own research. As only a few studies have dealt with agricultural contamination, we also studied a soil toposequence from Brittany, France, that experienced spreading of pig slurry for tens of years. In the surface horizons of the natural soils, the δ{sup 65}Cu values vary from − 0.15 to 0.44‰ and the δ{sup 66}Zn from − 0.03 to 0.43‰. Furthermore, vertical variations along soil profiles range from − 0.95 to 0.44‰ for δ{sup 65}Cu and from − 0.53 to 0.64‰ for δ{sup 66}Zn values. We concluded that pedogenetic processes can produce isotopic fractionation, yet, it is not always discernible and can be overprinted by an exogenous isotopic signature. Furthermore, some contaminants are enriched in heavy Cu or in light Zn compared to the rock or soil, but no generalization can be made. The anthropogenic inputs can be identified based on stable Cu and Zn isotope ratios if the isotope ratios of the sources are different from those of the soil, which needs to be tested for each individual case. - Highlights: • Pedogenetic processes produce some Cu and Zn isotope fractionation. • Pollution with distinct isotopic signatures can be traced using Cu and Zn isotopes. • Tracing

  15. Research on isotope geology: Isotopes ages of volcanic rocks from Ryeongnam Massif, Korea

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Seong Cheon; Chi, Se Jung; Kim, Yoo Sook [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1997-12-01

    Chronostratigraphy of most volcanic rocks in the Ryeongnam Massif have been undefined or mis-classified in different geological maps due to total absence of reported isotope ages. Twenty-four new isotope ages are given for age-undefined volcanic units and some related igneous bodies. Most of volcanic rocks show high [La/Yb]n ratios and LREE enrichments which are characteristics of subduction-related high-K calc-alkali volcanic rocks occurred in the active continental margin. Preliminary results on carbon and oxygen stable isotope ratios({delta}{sup 13}C=-1.7{approx}-6.2 per mil; {delta}{sup 18} O=-21.6{approx}-24.7 per mil) of druse- or phenocryst-calcite from andesitic and basaltic rocks in the southern coastal region indicate a magmatic origin. Based on new K-Ar whole-rock ages, chronological guidelines are established as follows: 1) Gayasan andesite (78{+-}4Ma) - Gurye andesitic tuff (81{+-}4Ma); 2) Gurye andesite (68{+-}4Ma) - Suncheon andesitic tuff (67{+-}3Ma) - Yeosu basaltic andesite (67{+-}3Ma) - Narodo andesite (70{+-}3Ma); 3) Taebaeg Baegbyeongsan basaltic andesite (62{+-}3Ma) - Gurye Obongsan andesite (64{+-}3Ma) - Yeosu dacite (63{+-}3Ma) - Dolsando andesite (62{+-}3Ma) - Jangheung Buyongsan andesite (65{+-}3Ma); 4) Suncheon Joryedong andesite (55{+-}2Ma) - Goheung andesite (56{+-}3Ma); 5) Taebaeg Baegbyeonsan basaltic andesite (48{+-}2Ma) - Yeosu basalt (51{+-}3Ma). Resetted age (49{+-}2Ma) of an intrusive rhyolite implies the timing of thermal alteration in the Wondong Fe-Mine of the Taebaegsan Mineralized Belt. K-Ar hornblende ages of two hornblendite stocks in the southern Jangsu suggests apparent emplacement-ages of late Triassic (210{+-}9Ma) and early Permian (274{+-}10Ma), independently. K-Ar hornblende age (1023{+-}37Ma) of the Ogbang amphibolite implies a reduction of original age due to later thermal effect probably attributed to either later intrusion or regional metamorphism. (author). 56 refs., 19 tabs., 14 figs.

  16. Isotope pattern deconvolution as rising tool for isotope tracer studies in environmental research

    Science.gov (United States)

    Irrgeher, Johanna; Zitek, Andreas; Prohaska, Thomas

    2014-05-01

    During the last decade stable isotope tracers have emerged as versatile tool in ecological research. Besides 'intrinsic' isotope tracers caused by the natural variation of isotopes, the intentional introduction of 'extrinsic' enriched stable isotope tracers into biological systems has gained significant interest. Hereby the induced change in the natural isotopic composition of an element allows amongst others for studying the fate and fluxes of metals, trace elements and species in organisms or provides an intrinsic marker or tag of particular biological samples. Due to the shoreless potential of this methodology, the number of publications dealing with applications of isotope (double) spikes as tracers to address research questions in 'real world systems' is constantly increasing. However, some isotope systems like the natural Sr isotopic system, although potentially very powerful for this type of application, are still rarely used, mainly because their adequate measurement/determination poses major analytical challenges; as e.g. Sr is available in significant amounts in natural samples. In addition, biological systems underlie complex processes such as metabolism, adsorption/desorption or oxidation/reduction. As a consequence, classic evaluation approaches such as the isotope dilution mass spectrometry equation are often not applicable because of the unknown amount of tracer finally present in the sample. Isotope pattern deconvolution (IPD), based on multiple linear regression, serves as simplified alternative data processing strategy to double spike isotope dilution calculations. The outstanding advantage of this mathematical tool lies in the possibility of deconvolving the isotope pattern in a spiked sample without knowing the quantities of enriched isotope tracer being incorporated into the natural sample matrix as well as the degree of impurities and species-interconversion (e.g. from sample preparation). Here, the potential of IPD for environmental tracer

  17. Stable isotope production with laser techniques; Production d`isotopes stables a l`aide des techniques laser

    Energy Technology Data Exchange (ETDEWEB)

    Petit, A. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Procedes d`Enrichissement

    1994-12-31

    Laser properties may be used for stable isotope production either by selective photoionization of an atom particular isotope, either by selective photodissociation of a molecule. Principles of both processes are reviewed and examples of calcium 43 isotope separation through photoionization and of carbon and oxygen isotope separation by photodissociation are presented. 4 figs., 1 tab., 11 refs.

  18. Beam delivery for stable isotope separation

    Science.gov (United States)

    Forbes, Andrew; Strydom, Hendrick J.; Botha, Lourens R.; Ronander, Einar

    2002-10-01

    In the multi-photon dissociation process of Carbon isotope enrichment, IR photons are used to selectively excite a molecule with the given isotopic base element. This enrichment process is very sensitive to the beam's intensity and wavelength. Because the intensity is determined by the propagation of the field, the enrichment factors are also very dependent on the field propagation. In this paper, the influence of the wavelength and intensity of the beam, on the isotope selective dissociation of a CFC compound is investigated both experimentally and theoretically. Consideration is also given to some of the factors that influence the delivery of various beams to the reactor chamber, and their subsequent propagation through the reactor. The results show that suitable beam forming can lead to an improved isotope separation process.

  19. On the progress in stable isotope separation

    Energy Technology Data Exchange (ETDEWEB)

    Prusakov, V.N. [Kurchatov Institute, Moscow (Russian Federation)

    1994-12-31

    The principles and process of centrifuge isotope separation are reviewed; the fundamental advantage of the centrifuge over gaseous diffusion arises from the fact that the primary isotope separation effect occurs at thermodynamic equilibrium; thus, gas centrifuge enrichment uses only about 1/20 to 1/30 of the electricity per SWU (separation work unit) consumed by gaseous diffusion. The various substances that can be used in centrifuge isotope separation are listed (fluorides, oxyfluorides, {pi}-complexes, boron hydrides, metal-organic compounds, halides...). The centrifuge method productivity is much greater than with the electromagnetic separation technique; examples of centrifuge stable and radioactive isotope separation are given; the method of the residue reduction is also presented with the example of separating radioactive krypton-85 out of a nuclear reactor krypton blend. 4 figs.

  20. Stable Oxygen-18 and Deuterium Isotopes

    DEFF Research Database (Denmark)

    Müller, Sascha

    development within a given lowland headwater catchment (stream water isotopes). Based on our investigations on the precipitation isotopic composition a local meteoric water line (LMWL) was constructed and expressed as: δ2H=7.4 δ18O + 5.36‰. Moreover, we showed that under maritime temperature climate influence......, humidity is the main driver for the temporal and spatial isotopic development and temperature plays only a secondary role. Based on our investigations at a coastal lagoon aquifer we could improve quantifications of seasonal saltwater-wedge dynamics, based on isotopic tracers combined with salinity. We can...... link the observed seasonal regression/transgression pattern to the inland recharge cycle, which is expressed in hydraulic head configuration and submarine groundwater discharge rates at the fieldsite. Nonetheless, those observed dynamics could not be simulated due to numerical limitations. By the use...

  1. Development of proliferation resistant isotope separation technology

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Doyoung; Ko, Kwanghoon; Kim, Taeksoo; Park, Hyunmin; Lim, Gwon; Cha, Yongho; Han, Jaemin; Baik, Sunghoon; Cha, Hyungki

    2012-02-15

    This project was accomplished with an aim of establishing the industrial facilities for isotope separation in Korea. The experiment for the measurement of neutrino mass that has been an issue in physics, needs very much of enriched calcium-48 isotope. However, calcium-48 isotope can be produced only by the electro-magnetic method and, thus, its price is very expensive. Therefore, we expect that ALSIS can replace the electro-magnetic method for calcium-48 isotope production. In this research stage, the research was advanced systematically with core technologies, such as atomic vapor production, the measurement of vapor characteristics and stable and powerful laser development. These researches will be the basis of the next research stages. In addition, the international research trends and cooperation results are reported in this report.

  2. Isotope effects of hydrogen and atom tunnelling

    Science.gov (United States)

    Buchachenko, A. L.; Pliss, E. M.

    2016-06-01

    The abnormally high mass-dependent isotope effects in liquid-phase hydrogen (deuterium) atom transfer reactions, which are customarily regarded as quantum effects, are actually the products of two classical effects, namely, kinetic and thermodynamic ones. The former is determined by the rate constants for atom transfer and the latter is caused by nonbonded (or noncovalent) isotope effects in the solvation of protiated and deuterated reacting molecules. This product can mimic the large isotope effects that are usually attributed to tunnelling. In enzymatic reactions, tunnelling is of particular interest; its existence characterizes an enzyme as a rigid molecular machine in which the residence time of reactants on the reaction coordinate exceeds the waiting time for the tunnelling event. The magnitude of isotope effect becomes a characteristic parameter of the internal dynamics of the enzyme catalytic site. The bibliography includes 61 references.

  3. Quantification of isotopic turnover in agricultural systems

    Science.gov (United States)

    Braun, A.; Auerswald, K.; Schnyder, H.

    2012-04-01

    The isotopic turnover, which is a proxy for the metabolic rate, is gaining scientific importance. It is quantified for an increasing range of organisms, from microorganisms over plants to animals including agricultural livestock. Additionally, the isotopic turnover is analyzed on different scales, from organs to organisms to ecosystems and even to the biosphere. In particular, the quantification of the isotopic turnover of specific tissues within the same organism, e.g. organs like liver and muscle and products like milk and faeces, has brought new insights to improve understanding of nutrient cycles and fluxes, respectively. Thus, the knowledge of isotopic turnover is important in many areas, including physiology, e.g. milk synthesis, ecology, e.g. soil retention time of water, and medical science, e.g. cancer diagnosis. So far, the isotopic turnover is quantified by applying time, cost and expertise intensive tracer experiments. Usually, this comprises two isotopic equilibration periods. A first equilibration period with a constant isotopic input signal is followed by a second equilibration period with a distinct constant isotopic input signal. This yields a smooth signal change from the first to the second signal in the object under consideration. This approach reveals at least three major problems. (i) The input signals must be controlled isotopically, which is almost impossible in many realistic cases like free ranging animals. (ii) Both equilibration periods may be very long, especially when the turnover rate of the object under consideration is very slow, which aggravates the first problem. (iii) The detection of small or slow pools is improved by large isotopic signal changes, but large isotopic changes also involve a considerable change in the input material; e.g. animal studies are usually carried out as diet-switch experiments, where the diet is switched between C3 and C4 plants, since C3 and C4 plants differ strongly in their isotopic signal. The

  4. Use of fluorescent screens for isotope radiography

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, S. K.

    1979-01-01

    Radiographic examination can be performed on items beyond the limitation of conventional isotope radiography without a great loss of resolution. With proper film and screen selection and scatter radiation control, fluorescent screens can be a valuable additional tool for radiography.

  5. Carbon isotopic fractionation in heterotrophic microbial metabolism

    Science.gov (United States)

    Blair, N.; Leu, A.; Munoz, E.; Olsen, J.; Kwong, E.; Des Marais, D.

    1985-01-01

    Differences in the natural-abundance carbon stable isotopic compositions between products from aerobic cultures of Escherichia coli K-12 were measured. Respired CO2 was 3.4 percent depleted in C-13 relative to the glucose used as the carbon source, whereas the acetate was 12.3 percent enriched in C-13. The acetate C-13 enrichment was solely in the carboxyl group. Even though the total cellular carbon was only 0.6 percent depleted in C-13, intracellular components exhibited a significant isotopic heterogeneity. The protein and lipid fractions were -1.1 and -2.7 percent, respectively. Aspartic and glutamic acids were -1.6 and +2.7 percent, respectively, yet citrate was isotopically identical to the glucose. Probable sites of carbon isotopic fractionation include the enzyme, phosphotransacetylase, and the Krebs cycle.

  6. Robust optical carbon dioxide isotope analyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Isotopic analysis of carbon dioxide is an important tool for characterization of the exchange and transformation of carbon between the biosphere and the atmosphere....

  7. The anomalous quadrupole collectivity in Te isotopes

    CERN Document Server

    Qi, Chong

    2016-01-01

    We present systematic calculations on the spectroscopy and transition properties of even-even Te isotopes by using the large-scale configuration interaction shell model approach with a realistic interaction. These nuclei are of particular interest since their yrast spectra show a vibrational-like equally-spaced pattern but the few known E2 transitions show anomalous rotational-like behavior, which cannot be reproduced by collective models. Our calculations reproduce well the equally-spaced spectra of those isotopes as well as the constant behavior of the $B(E2)$ values in $^{114}$Te. The calculated $B(E2)$ values for neutron-deficient and heavier Te isotopes show contrasting different behaviors along the yrast line. The $B(E2)$ of light isotopes can exhibit a nearly constant bevavior upto high spins. We show that this is related to the enhanced neutron-proton correlation when approaching $N=50$.

  8. Separation of Isotopes via Dynamical Delocalization

    Institute of Scientific and Technical Information of China (English)

    Farhan Saif

    2008-01-01

    Based on the dynamical de-localization phenomenon we show that different isotopes of a material can be separated.We explain that the suggested scheme can be realized in the laboratory using presently available experimental facilities.

  9. Preparation of Metallic Isotope 26Mg

    Institute of Scientific and Technical Information of China (English)

    WuXiaolei; ZhangFuming; GanZaiguo; GuoJunsheng; QinZhi

    2003-01-01

    Some special isotope material is usually used in nuclear experiments. It can be served as ion beam or target. When new superheavy nuclide 265Bh (Z=107) is synthesized, a reaction of 243Am target with 26Mg ion beamis selected to produce new isotope 265Bh. The preparation and production of this rare and extremely expensive isotope 26 Mg used for ion beam substance will be a key problem in synthesizing experiment of 265Bh. Theavailable chemical form of isotope 26Mg in commercial product usually is oxide or other compound, which are not required in our experiment. They need to be transformed to metal form as a proper working substance in ion source.

  10. Stable N isotope values of black spruce ecosystem components integrate source N isotope values, soil fertility, and microbial biomass: a natural and experimental study from Alaska

    Science.gov (United States)

    Mayor, J. R.; Schuur, T.; Mack, M. C.; Nettelton Hollingsworth, T.; Bååth, E.

    2009-12-01

    approach that of the source N isotope values. This suggested black spruce switched from fungal delivered N to direct uptake of fertilizer. This was corroborated by the observation that N fertilization alone also suppressed the biomass of standing and actively growing fungi in soils. Surprisingly, P fertilization stimulated resin exchangeable pools of soil NO3 and led to significant enrichment of the residual soil NO3-N isotope pool by 18‰ relative to the control. Fractionation against 15N during denitrification of the increased NO3 concentrations could account for the isotopic enrichment. Combined, our natural gradient and experimental approach illustrated that measuring numerous ecosystem components, including source N isotope values, are necessary to understand the isotopic variability in a landscape dominated by a single species of tree. It also illustrated how the biomass, and presumed activity, of ECM fungi fluctuates across the landscape in response to shifting soil fertility.

  11. Isotope shortage triggers delays for patients

    Science.gov (United States)

    Gould, Paula

    2009-07-01

    An unplanned shutdown of a nuclear reactor in Canada is disrupting the supply of medical isotopes across North America and forcing some hospitals to cancel or postpone patients' tests. The closure of the National Research Universal (NRU) reactor in Chalk River, Ontario, has also embarrassed Canadian officials, including a senior government minister who was forced to apologize after calling the isotope shortage a "sexy" career challenge.

  12. Mixed Population Screening for Sulfur Isotopes

    Institute of Scientific and Technical Information of China (English)

    CUI Bin; ZHAO Lei; ZHAN Zhaoyang; HE Zhijun

    2004-01-01

    Quantitative research of the origin of sulfur isotopes is a difficult problem that has puzzled geochemists all along. In the study of the middle and lower reaches of the Yangtze River and the Dongpo orefield in Hunan Province,the authors successfully applied the mathematical model of mixed population screening to quantitatively resolving the problem on the origin of sulfur isotopes, which is significant in finding out the source of mineralizing matter and metallogenic mechanisms.

  13. Hydrogen isotope effect on the Dimits shift

    Science.gov (United States)

    Itoh, S.-I.; Itoh, K.

    2016-10-01

    The hydrogen isotope effect on the Dimits shift in drift wave turbulence (Dimits et al 2000 Phys. Plasmas 7 969) is discussed using the theory of zonal flows, in which the nonlinear damping rate of zonal flows is taken into account. The up-shift of the critical linear growth rate of the drift waves, above which drift wave fluctuations develop, is investigated. The dependence on the mass number of the hydrogen isotope is discussed.

  14. Nickel isotopic composition of the mantle

    Science.gov (United States)

    Gall, Louise; Williams, Helen M.; Halliday, Alex N.; Kerr, Andrew C.

    2017-02-01

    This paper presents a detailed high-precision study of Ni isotope variations in mantle peridotites and their minerals, komatiites as well as chondritic and iron meteorites. Ultramafic rocks display a relatively large range in δ60 Ni (permil deviation in 60 Ni /58 Ni relative to the NIST SRM 986 Ni isotope standard) for this environment, from 0.15 ± 0.07‰ to 0.36 ± 0.08‰, with olivine-rich rocks such as dunite and olivine cumulates showing lighter isotope compositions than komatiite, lherzolite and pyroxenite samples. The data for the mineral separates shed light on the origin of these variations. Olivine and orthopyroxene display light δ60 Ni whereas clinopyroxene and garnet are isotopically heavy. This indicates that peridotite whole-rock δ60 Ni may be controlled by variations in modal mineralogy, with the prediction that mantle melts will display variable δ60 Ni values due to variations in residual mantle and cumulate mineralogy. Based on fertile peridotite xenoliths and Phanerozoic komatiite samples it is concluded that the upper mantle has a relatively homogeneous Ni isotope composition, with the best estimate of δ60Nimantle being 0.23 ± 0.06‰ (2 s.d.). Given that >99% of the Ni in the silicate Earth is located in the mantle, this also defines the Ni isotope composition of the Bulk Silicate Earth (BSE). This value is nearly identical to the results obtained for a suite of chondrites and iron meteorites (mean δ60 Ni 0.26 ± 0.12‰ and 0.29 ± 0.10‰, respectively) showing that the BSE is chondritic with respect to its Ni isotope composition, with little to no Ni mass-dependent isotope fractionation resulting from core formation.

  15. IBFM for Ba isotopes and chaoticity

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Cata-Danil, G.; Ivascu, M.; Ur, C.A. (Inst. of Atomic Physics, Bucharest (Romania)); Gizon, A.; Gizon, J. (Inst. des Sciences Nucleaires, 38 - Grenoble (France))

    1992-08-01

    Fluctuation properties have been analysed for the energy levels predicted by IBFM calculations in the Ba isotopes {sup 121}Ba to {sup 131}Ba. The results indicate, in general, a situation which is close to the chaotic limit. For the lighter isotopes studied (121 and 123), a phase transition is obtained in the low-spin, positive parity states, from a situation close to regularity at low excitation energies, towards chaoticity at higher excitations. (orig.).

  16. IBFM for barium isotopes and chaoticity

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Cata-Danil, G.; Ivascu, M.; Ur, C.A. (Institute of Atomic Physics, Bucharest (Romania)); Gizon, A.; Gizon, J. (Institute des Sciences Nucleaires, Grenoble (France))

    1992-01-01

    Fluctuation properties have been analysed for the energy levels predicted by IBFM calculations in the Ba isotopes {sup 121}Ba to {sup 131}Ba. The results are indicating, in general, a situation which is close to the chaotic limit. For the lighter isotopes studied (121 and 131), a phase transition is obtained in the low-spin, positive states, from a situation close to regularity at low excitation energies, towards chaoticity at higher excitations. (author).

  17. IBFM for barium isotopes and chaoticity

    Science.gov (United States)

    Bucurescu, D.; Cata-Danil, G.; Ivascu, M.; Gizon, A.; Gizon, J.; UR, C. A.

    Fluctuation properties have been analysed for the energy levels predicted by IBFM calculations in the Ba isotopes 121Ba to 131Ba. The results are indicating, in general, a situation which is close to the chaotic limit. For the lighter isotopes studied (121 and 131), a phase transition is obtained in the low-spin, positive states, from a situation close to regularity at low excitation energies, towards chaoticity at higher excitations.

  18. Magnesium isotope geochemistry in arc volcanism

    Science.gov (United States)

    Teng, Fang-Zhen; Hu, Yan

    2016-01-01

    Incorporation of subducted slab in arc volcanism plays an important role in producing the geochemical and isotopic variations in arc lavas. The mechanism and process by which the slab materials are incorporated, however, are still uncertain. Here, we report, to our knowledge, the first set of Mg isotopic data for a suite of arc lava samples from Martinique Island in the Lesser Antilles arc, which displays one of the most extreme geochemical and isotopic ranges, although the origin of this variability is still highly debated. We find the δ26Mg of the Martinique Island lavas varies from −0.25 to −0.10, in contrast to the narrow range that characterizes the mantle (−0.25 ± 0.04, 2 SD). These high δ26Mg values suggest the incorporation of isotopically heavy Mg from the subducted slab. The large contrast in MgO content between peridotite, basalt, and sediment makes direct mixing between sediment and peridotite, or assimilation by arc crust sediment, unlikely to be the main mechanism to modify Mg isotopes. Instead, the heavy Mg isotopic signature of the Martinique arc lavas requires that the overall composition of the mantle wedge is buffered and modified by the preferential addition of heavy Mg isotopes from fluids released from the altered subducted slab during fluid−mantle interaction. This, in turn, suggests transfer of a large amount of fluid-mobile elements from the subducting slab to the mantle wedge and makes Mg isotopes an excellent tracer of deep fluid migration. PMID:27303032

  19. IUPAC Periodic Table of the Isotopes

    Science.gov (United States)

    Holden, N.E.; Coplen, T.B.; Böhlke, J.K.; Wieser, M.E.; Singleton, G.; Walczyk, T.; Yoneda, S.; Mahaffy, P.G.; Tarbox, L.V.

    2011-01-01

    For almost 150 years, the Periodic Table of the Elements has served as a guide to the world of elements by highlighting similarities and differences in atomic structure and chemical properties. To introduce students, teachers, and society to the existence and importance of isotopes of the chemical elements, an IUPAC Periodic Table of the Isotopes (IPTI) has been prepared and can be found as a supplement to this issue.

  20. Surfaces that become isotopic after Dehn filling

    CERN Document Server

    Bachman, David; Sedgwick, Eric

    2010-01-01

    We show that after generic filling along a torus boundary component of a 3-manifold, no two closed, 2-sided, essential surfaces become isotopic, and no closed, 2-sided, essential surface becomes inessential. That is, the set of essential surfaces (considered up to isotopy) survives unchanged in all suitably generic Dehn fillings. Furthermore, for all but finitely many non-generic fillings, we show that two essential surfaces can only become isotopic in a constrained way.

  1. The Facility for Rare Isotope Beams

    OpenAIRE

    Wrede C.

    2015-01-01

    The Facility for Rare Isotope Beams (FRIB) is a United States Department of Energy user facility currently under construction on the campus of Michigan State University. Based on a 400 kW, 200 MeV/u heavy-ion driver linac, FRIB will deliver high-quality fast, thermalized, and re-accelerated beams of rare isotopes with unprecedented intensities to a variety of experimental areas and equipment. New science opportunities at the frontiers of nuclear structure, nuclear astrophysics, fundamental sy...

  2. The Marine Biogeochemistry of Zinc Isotopes

    Science.gov (United States)

    2007-06-01

    dust (Niger) Sapropel (Mediterranean) 4* Deep-Sea Sediments * • Lobster Liver Mussel tissue Plankton Zooplankton Zinc ores * * * Sediment trap material...of natural plankton over large changes in nutrient concentrations in the Peru Upwelling Region. This suggests either that the isotope effect for Zn...hydrothermal fluids and minerals, cultured marine phytoplankton, natural plankton , and seawater. By measuring Zn isotopes in a diverse array of

  3. The discovery of isotopes a complete compilation

    CERN Document Server

    Thoennessen, Michael

    2016-01-01

    This book describes the exciting discovery of every isotope observed on earth to date, which currently numbers some 3000. For each isotope a short essay highlights the authors of the first publication for the isotope, the laboratory and year where and when the isotope was discovered, as well as details about the production and detection methods used. In controversial cases previously claims are also discussed. At the end a comprehensive table lists all isotopes sorted by elements and a complete list of references. Preliminary versions of these paragraphs have been published over the last few years as separate articles in the journal "Atomic Data and Nuclear Data Tables". The work re-evaluates all assignments judging them with a uniform set of criteria. In addition, the author includes over 100 new isotopes which have been discovered since the articles published. This book is a source of information for researchers as well as enthusiastic laymen alike. From the prepublication review: “The explanations focus ...

  4. Isotopic discrimination of zinc in higher plants.

    Science.gov (United States)

    Weiss, D J; Mason, T F D; Zhao, F J; Kirk, G J D; Coles, B J; Horstwood, M S A

    2005-03-01

    * The extent of isotopic discrimination of transition metals in biological processes is poorly understood but potentially has important applications in plant and biogeochemical studies. * Using multicollector inductively coupled plasma (ICP) mass spectrometry, we measured isotopic fractionation of zinc (Zn) during uptake from nutrient solutions by rice (Oryza sativa), lettuce (Lactuca sativa) and tomato (Lycopersicon esculentum) plants. * For all three species, the roots showed a similar extent of heavy Zn enrichment relative to the nutrient solution, probably reflecting preferential adsorption on external root surfaces. By contrast, a plant-species specific enrichment of the light Zn isotope occurred in the shoots, indicative of a biological, membrane-transport controlled uptake into plant cells. The extent of the fractionation in the shoots further depended on the Zn speciation in the nutrient solution. * The observed isotopic depletion in heavy Zn from root to shoot (-0.13 to -0.26 per atomic mass unit) is equivalent to roughly a quarter of the total reported terrestrial variability of Zn isotopic compositions (c. 0.84 per atomic mass unit). Plant uptake therefore represents an important source of isotopic variation in biogeochemical cycling of Zn.

  5. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  6. The evolution of Carbon isotopes in calcite in the presence of cyanobacteria

    Science.gov (United States)

    Grimm, Christian; Mavromatis, Vasileios; Pokrovsky, Oleg S.; Oelkers, Eric H.

    2016-04-01

    Stable isotopic compositions in carbonates are widely used as indicators of environmental conditions prevailing during mineral formation. This reconstruction is substantially based on the assumption that there is no change in the mineral composition over geological time. However, recent experimental studies have shown that carbon and magnesium isotopes in hydrous Mg-carbonates undergo continuous re-equilibration with the ambient solution even after mineral precipitation stopped ([1] and [2], respectively). To verify whether this holds true for anhydrous Ca-bearing carbonates which readily form at earth's surface environments, a series of batch system calcite precipitation experiments were performed in the presence of actively growing cyanobacteria Synechococcus sp. The bacteria were grown at ambient temperature in a BG11 culture medium (SIGMA C3061) and continuous stirring, air-bubbling and illumination. Calcite precipitation was initiated by the addition of 8.5mM CaCl2 and 0-50 mM NaHCO3 or NaHCO3-Na2CO3 mixtures. The presence of cyanobacteria is on one hand promoting CaCO3 formation due to increasing pH resulting from photosynthesis. On the other hand, actively growing cyanobacteria drastically change carbon isotope signature of the aqueous fluid phase by preferably incorporating the lighter 12C isotope into biomass [1]. This study explores the effect of continuously changing carbon isotope compositions in dissolved inorganic carbon (DIC) on precipitated calcite which is in chemical equilibrium with the ambient fluid phase. [1] Mavromatis et al. (2015). The continuous re-equilibration of carbon isotope compositions of hydrous Mg-carbonates in the presence of cyanobacteria. Chem. Geol. 404, 41-51 [2] Mavromatis et al. (2012). Magnesium isotope fractionation during hydrous magnesium carbonate precipitation with and without cyanobacteria. Geochim. Cosmochim. Acta 76, 161-174

  7. Fractionation of Nitrogen and Oxygen Isotopes During Microbial Nitrate Reduction

    Science.gov (United States)

    Lehmann, M. F.; Bernasconi, S. M.; Reichert, P.; Barbieri, A.; McKenzie, J. A.

    2001-12-01

    reduction barely contributes to the observed nitrate depletion in the water column. However, being mainly fuelled by NO3- from nitrifying activity at the sediment-water interface above the redoxcline, sedimentary nitrate reduction may still play an important role in the overall N budget of Lake Lugano without affecting the water column signal. The combined measurements of N and O isotope ratios in nitrate revealed that a significant contribution from coupled nitrification-denitrification in the open-water column could be excluded. The determination of δ 15N and δ 18O values in the water-column nitrate proved to be an effective tool to assess nitrate dissimilation in a hypolimnetic redox-transition zone. Moreover, the dual-isotope approach allowed deconvolving the effects of coexisting N-cycling processes. Hence, this study confirms the high potential of δ 18O values for nitrate as a valuable biogeochemical tracer in aquatic systems, complementing nitrate δ 15N values. Brandes J.A. and Devol, A. H., Geochim. Cosmochim. Acta 61(9), 1997.

  8. Identification of isotopically primitive interplanetary dust particles: A NanoSIMS isotopic imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Floss, C; Stadermann, F J; Bradley, J P; Dai, Z R; Bajt, S; Graham, G; Lea, A S

    2005-09-02

    We have carried out a comprehensive survey of the isotopic compositions (H, B, C, N, O, S) of a suite of interplanetary dust particles (IDPs), including both cluster and individual particles. Isotopic imaging with the NanoSIMS shows the presence of numerous discrete hotspots that are strongly enriched in {sup 15}N, including the largest {sup 15}N enrichments ({approx}1300 {per_thousand}) observed in IDPs to date. A number of the IDPs also contain larger regions with more modest enrichments in {sup 15}N, leading to average bulk N isotopic compositions that are {sup 15}N-enriched in these IDPs. Although C isotopic compositions are normal in most of the IDPs, two {sup 15}N-rich N-hotspots have correlated {sup 13}C anomalies. CN{sup -}/C{sup -} ratios suggest that most of the {sup 15}N-rich hotspots are associated with relatively N-poor carbonaceous matter, although specific carriers have not been determined. H isotopic distributions are similar to those of N: D anomalies are present both as distinct very D-rich hotspots and as larger regions with more modest enrichments. Nevertheless, H and N isotopic anomalies are not directly correlated, consistent with results from previous studies. Oxygen isotopic imaging shows the presence of abundant presolar silicate grains in the IDPs. The O isotopic compositions of the grains are similar to those found in presolar oxide and silicate grains from primitive meteorites. Most of the silicate grains in the IDPs have isotopic ratios consistent with meteoritic Group 1 oxide grains, indicating origins in oxygen-rich red giant and asymptotic giant branch stars, but several presolar silicates exhibit the {sup 17}O and {sup 18}O enrichments of Group 4 oxide grains, whose origin is less well understood. Based on their N isotopic compositions, the IDPs studied here can be divided into two groups. One group is characterized as being ''isotopically primitive'' and consists of those IDPs that have anomalous bulk N isotopic

  9. Deuterium isotope effect on the intramolecular electron transfer in Pseudomonas aeruginosa azurin

    DEFF Research Database (Denmark)

    Farver, O.; Zhang, Jingdong; Chi, Qijin;

    2001-01-01

    rather than negative. Isotope effects are, however, also inherent in the nuclear reorganization Gibbs free energy and in the tunneling factor for the electron transfer process. A slightly larger thermal protein expansion in H2O than in D2O (0.001 nm K-1) is sufficient both to account for the activation......Intramolecular electron transfer in azurin in water and deuterium oxide has been studied over a broad temperature range. The kinetic deuterium isotope effect, k(H)/k(D), is smaller than unity (0.7 at 298 K), primarily caused by the different activation entropies in water (-56.5 J K-1 mol(-1...... entropy difference and to compensate for the different temperature dependencies of E-0'. Thus, differences in driving force and thermal expansion appear as the most straightforward rationale for the observed isotope effect....

  10. Development and application of isotopes and radiation technology in Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Djaloeis, A. [DDG, Batan, Jakarta (Indonesia)

    1997-10-01

    The National Atomic Energy Agency (BATAN) of the Republic of Indonesia is the highest agency in the country, charged amongst others with the development and application of Isotopes and Radiation Technology as a tool in the search for the optimal solution of various national development problems, such as those encountered in the fields of Agriculture, Livestock, health/medicine, Industry, Environment and Energy. The acquisition and development of the scientific and technical expertise, R and D facilities/instruments and infrastructure have been achieved primarily through bilateral and multilateral collaborative activities with domestic, foreign and international institutions. On the basis of the achieved R and D results, the acquired techniques have been progressively transferred to the end-users and applied in solving scientific-technical problems in the aforementioned fields. This paper gives a brief overview of the present status and future trend of activities in the development and applications of isotopes and radiation technology in Agriculture, Livestock and Industry in Indonesia. In the field of Agriculture the research activities are focussed on obtaining and disseminating new crop varieties with desired specific characteristics and on increasing soil fertilizer efficiency. These research results and those on livestock feed supplementation formula and disease prevention have been applied in helping farmers in various parts of Indonesia to increase their productivity. In industry, irradiation technology for food preservation and sterilization has been successfully transferred to the commercial companies. The same is also true for Non-Destructive Examination, Radioactive Tracer and Radiation Based Process Monitoring Techniques. Natural and radioactive isotopes have been widely used also in hydrology, sedimentology and geothermal studies. Highlights of the results are presented and discussed

  11. Diffusion in isotopically controlled semiconductor systems

    Science.gov (United States)

    Bracht, H.

    1999-12-01

    Isotopically controlled heterostructures of 28Si/natSi and Al71GaAs/Al69GaAs/71GaAs have been used to study the self-diffusion process in this elemental and compound semiconductor material. The directly measured Si self-diffusion coefficient is compared with the self-interstitial and vacancy contribution to self-diffusion which were deduced from metal diffusion experiments. The remarkable agreement between the Si self-diffusion coefficients and the individual contributions to self-diffusion shows that both self-interstitials and vacancies mediate Si self-diffusion. The Ga self-diffusion in undoped AlGaAs was found to decrease with increasing Al concentration. The activation enthalpy of Ga and Al diffusion in GaAs and of Ga diffusion in AlGaAs all lie in the range of (3.6±0.1) eV, but with different pre-exponential factors. The doping dependence of Ga self-diffusion reveals a retardation (enhancement) of Ga diffusion under p-type (n-type) doping compared to intrinsic conditions. All experimental results on the group-III atom diffusion are accurately described if vacancies on the group-III sublattice are assumed to mediate the Ga self- and Al-Ga interdiffusion in undoped AlGaAs and the Ga self-diffusion in Be- and Si-doped GaAs with an active dopant concentration of 3×1018 cm-3. The doping dependence of Ga self-diffusion in GaAs provides strong evidence that neutral, singly and doubly charged Ga vacancies govern the self-diffusion process.

  12. Radioactive isotope production for medical applications using Kharkov electron driven subcritical assembly facility.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, Y.; Nuclear Engineering Division

    2007-05-15

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine has a plan to construct an accelerator driven subcritical assembly. The main functions of the subcritical assembly are the medical isotope production, neutron thereby, and the support of the Ukraine nuclear industry. Reactor physics experiments and material research will be carried out using the capabilities of this facility. The United States of America and Ukraine have started collaboration activity for developing a conceptual design for this facility with low enrichment uranium (LEU) fuel. Different conceptual designs are being developed based on the facility mission and the engineering requirements including nuclear physics, neutronics, heat transfer, thermal hydraulics, structure, and material issues. Different fuel designs with LEU and reflector materials are considered in the design process. Safety, reliability, and environmental considerations are included in the facility conceptual design. The facility is configured to accommodate future design improvements and upgrades. This report is a part of the Argonne National Laboratory Activity within this collaboration for developing and characterizing the subcritical assembly conceptual design. In this study, the medical isotope production function of the Kharkov facility is defined. First, a review was carried out to identify the medical isotopes and its medical use. Then a preliminary assessment was performed without including the self-shielding effect of the irradiated samples. Finally, more detailed investigation was carried out including the self-shielding effect, which defined the sample size and irradiation location for producing each medical isotope. In the first part, the reaction rates were calculated as the multiplication of the cross section with the unperturbed neutron flux of the facility. Over fifty isotopes were considered and all transmutation channels are used including (n,{gamma}), (n,2n), (n,p), and ({gamma},n). In the second part

  13. Isotopic evolution of Mauna Loa volcano

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, M.D.; Kammer, D.P. (Chemistry Dept., Woods Hole Oceanographic Institution, MA (USA))

    1991-04-01

    In an effort to understand the temporal helium isotopic variations in Mauna Loa volcano, we have measured helium, strontium and lead isotopes in a suite of Mauna Loa lavas that span most of the subaerial eruptive history of the volcano. The lavas range in age from historical flows to Ninole basalt which are thought to be several hundred thousand years old. Most of the samples younger than 30 ka in age (Kau Basalt) are radiocarbon-dated flows, while the samples older than 30 ka are stratigraphically controlled (Kahuku and Ninole Basalt). The data reveal a striking change in the geochemistry of the lavas approximately 10 ka before present. The lavas older than 10 ka are characterized by high {sup 3}He/{sup 4}He ({approx equal} 16-20 times atmospheric), higher {sup 206}Pb/{sup 204}Pb ({approx equal} 18.2), and lower {sup 87}Sr/{sup 86}Sr({approx equal} 0.70365) ratios than the younger Kau samples (having He, Pb and Sr ratios of approximately 8.5 x atmospheric, 18.1 and 0.70390, respectively). The historical lavas are distinct in having intermediate Sr and Pb isotopic compositions with {sup 3}He/{sup 4}He ratios similar to the other young Kau basalt ({approx equal} 8.5 x atmospheric). The isotopic variations are on a shorter time scale (100 to 10,000 years) than has previously been observed for Hawaiian volcanoes, and demonstrate the importance of geochronology and stratigraphy to geochemical studies. The data show consistency between all three isotope systems, which suggests that the variations are not related to magma chamber degassing processes, and that helium is not decoupled from the other isotopes. However, the complex temporal evolution suggests that three distinct mantle sources are required to explain the isotopic data. Most of the Mauna Loa isotopic variations could be explained by mixing between a plume type source, similar to Loihi, and an asthenospheric source with helium isotopic composition close to MORB and elevated Sr isotopic values. (orig./WL).

  14. Isotopic yield in cold binary fission of even-even $^{244-258}$Cf isotopes

    CERN Document Server

    Santhosh, K P; Krishnan, Sreejith

    2016-01-01

    The cold binary fission of even-even 244-258Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that highest yield for 244,246,248Cf isotopes are for the fragments with isotope of Pb (Z=82) as one fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the fragments with isotope of Hg (Z=80) as one fragment. In the case of 254,256,258Cf isotopes the highest yield is for the fragments with Sn (Z=50) as one fragment. Thus, the fragment combinations with maximum yield reveal the role of doubly magic and near doubly magic nuclei in binary fission. It is found that asymmetric splitting is favoured for Cf isotopes with mass number A 252. In the case of Cf isotope with A=252, there is an equal probability for asymmetric and symmetric splitti...

  15. Mobile measurement of methane: plumes, isotopes and inventory verification

    Science.gov (United States)

    Lowry, D.; Zazzeri, G.; Fisher, R. E.; France, J.; Al-Shalaan, A.; Lanoisellé, M.; Nisbet, E. G.

    2015-12-01

    Since 2013 the RHUL group has been identifying methane plumes from major UK sources using a Picarro 2301 coupled to the A0941 mobile module. Once identified the plumes have been sampled by filling Tedlar or Flexfoil bags for later carbon isotopic analysis by high-precision IRMS. This method has ben successfully deployed to isotopically characterize the main anthropogenic methane emitters in the UK (natural gas, coal, landfill, wastewater treatment, cattle; Zazzeri et al., 2015) and during overseas campaigns in eastern Australia (coal, cattle, legacy gas wells) and Kuwait (landfill, wastewater treatment, oil refineries, cattle, camels). This has identified strong similarities of isotopic signature for some sources (landfill, cattle), but large variations for others (natural gas, coal), which must be isotopically resolved at regional scale. Both landfill and natural gas emissions in SE England have tightly-constrained δ13C signatures, averaging -58 ± 3‰ and -36 ± 2‰, respectively, the latter being characteristic of homogenised North Sea gas supply. In contrast, signatures for coal mines in England and Wales fall in a range of 51.2 ± 0.3‰ to 30.9 ± 1.4‰, but can be tightly constrained by region. On a local scale in west London, repeat surveys in the boroughs of Hounslow and Runnymede have been made for comparison with the latest 1x1 km grid UK inventories for 2009 and 2012, which are subdivided by UNECE categories. An excess methane map can be derived for comparison with inventory emissions maps by identifying daily background and binning the excess values from mobile measurements by grid-square. This shows that the spatial distribution of emissions in the UK 2012 inventory is a big improvement on that of 2009. It also suggests that there is an overestimation of emissions from old landfills (closed before 2000 and reliant on a topsoil cap for oxidation), and an underestimation on emissions from currently active landfill cells. Zazzeri, G. et al. (2015

  16. Quantification soil production and erosion using isotopic techniques

    Science.gov (United States)

    Dosseto, Anthony; Suresh, P. O.

    2010-05-01

    Soil is a critical resource, especially in the context of a rapidly growing world's population. Thus, it is crucial to be able to quantify how soil resources evolve with time and how fast they become depleted. Over the past few years, the application of cosmogenic isotopes has permitted to constrain rates of soil denudation. By assuming constant soil thickness, it is also possible to use these denudation rates to infer soil production rates (Heimsath et al. 1997). However, in this case, it is not possible to discuss any imbalance between erosion and production, which is the core question when interested in soil resource sustainability. Recently, the measurement of uranium-series isotopes in soils has been used to quantify the residence time of soil material in the weathering profile and to infer soil production rates (Dequincey et al. 2002; Dosseto et al. 2008). Thus, the combination of U-series and cosmogenic isotopes can be used to discuss how soil resources evolve with time, whether they are depleting, increasing or in steady-state. Recent work has been undertaken in temperate southeastern Australia where a several meters thick saprolite is developed over a graniodioritc bedrock and underlains a meter or less of soil (Dosseto et al., 2008) and in tropical Puerto Rico, also in a granitic catchment. Results show that in an environment where human activity is minimal, soil and saprolite are renewed as fast as they are destroyed through denudation. Further work is investigating these processes at other sites in southeastern Australia (Frogs Hollow; Heimsath et al. 2001) and Puerto Rico (Rio Mameyes catchment; andesitic bedrock). Results will be presented and a review of the quantification of the rates of soil evolution using isotopic techniques will be given. Dequincey, O., F. Chabaux, et al. (2002). Chemical mobilizations in laterites: Evidence from trace elements and 238U-234U-230Th disequilibria. Geochim. Cosmochim. Acta 66(7): 1197-1210. Dosseto, A., S. P

  17. Lead isotopic evidence for selective uptake of radium in illite

    Energy Technology Data Exchange (ETDEWEB)

    Hidaka, H.; Horie, K. [Department of Earth and Planetary Systems Science, Hiroshima University Higashi-Hiroshima 739-8526 (Japan); Gauthier-Lafaye, F. [Centre de Geochimie de la Surface, UMR7517-CNRS-ULP, 67084 Strasbourg (France)

    2005-07-01

    Full text of publication follows: Radium has no stable isotopes. {sup 226}Ra having the longest half-life (T{sub 1/2} = 1600 year) among radium radioisotopes exists as a precursor of decay product from {sup 238}U in nature, and finally decays to the stable isotope {sup 206}Pb. Long-lived nuclides such as {sup 226}Ra may be profoundly fractionated from their parents in association with intense geochemical events in the terrestrial environments. Enrichment of Ra resulted from vegetation cycle and selective uptake into clay minerals has been reported [1,2]. It is of particular interest to understand the geochemical behaviors of Ra from the viewpoint of long-termed repository safety of radio-nuclear waste. We report here geochemical evidence of selective uptake of Ra ({sup 226}Ra) into clay minerals studied from the Pb isotopic compositions. The sample from sandstone layer at underground drift close to natural reactor zone 13 at the Oklo uranium deposits, Gabon. Several tiny illite grains sized about 100 {mu}m were found in fine calcite veins with 0.1 to 2 mm width in quartz matrix texture. Isotopic analyses of Pb and some related elements (U, Rb, Sr, Cs and Ba) in individual minerals were carried out by a Sensitive High Resolution Ion Microprobe (SHRIMP) at Hiroshima University. The Pb isotopic data of quartz and calcite in the sample provide the geochronological information corresponding to the formation of 2.15 billion year-old basement rocks and the occurrence of later hydrothermal activity in this region at 0.88 billion years, respectively. On the other hand, illite shows high enrichment of {sup 206}Pb, which cannot be explained simply from normal U decays. {sup 206}Po-enriched illite grains also show a strong enrichment of Ba. Such an enrichment of Ba is not observed in the neighboring minerals of illite grains. Considering that Ba has been used as a chemical tracer of {sup 226}Ra because of the chemical similarities between Ba and Ra, our result strongly

  18. 农业活动对表层岩溶泉溶解无机碳及稳定碳同位素的影响%Influence of Agricultural Activities on Dissolved Inorganic Carbon and Stable Isotopic of Epikarst Springs

    Institute of Scientific and Technical Information of China (English)

    张笑微; 周小萍; 徐尚全; 王鹏

    2013-01-01

    In this study, groundwater samples were collected from three epikarst springs, with same climatic and geological condition, but different agricultural activities. Impact of agriculture activities on karst process was explored by DIC and δ13CDIC values. The results showed that: Baishuwan spring which was not affected by agricultural activities had the highest DIC concentration332. 45 mg/L). The DIC concentration(235. 13 mg/L) of Lanhuagou spring was slightly lower, which was affected by agriculture activities. And Hougou spring had the lowest DIC concentration(203. 52 mg/L), owing to the most intense agriculture activities. Meanwhile, the δ13 CDIC value had an opposite trend with the intensity of agricultural activities: Baishuwan ( — 9. 84‰)activities could also affect the correlation between DIC and δ13 CDIC, which was better under non-anthropogenic condition (Baishuwan), and became faintness with the increase of agricultural activities intensity (Lanhuagou) , while no barely correlation was found at Hougou spring with the most intense agriculture activities. In summary, agricultural activities were not conducive to karst carbon sink. Suffering the threat of global warming, to increase the carbon sink, karst area should be returned farmland to forest, in order to maintain a good ecological environment.%以农业活动强度不同的3个表层岩溶泉为研究对象,通过分析不同泉点溶解无机碳(DIC)及稳定碳同位素(δ13CDIC)的变化,探讨农业活动对岩溶作用的影响.结果表明,无农业活动影响下的柏树湾泉DIC浓度最高(332.45 mg/L),少量农业活动影响下的兰花沟泉DIC浓度次之(235.13 mg/L),农业活动影响强烈的后沟泉DIC浓度最低(203.52 mg/L);随农业活动强度增加,δ13 CDIC值呈现与之相反的趋势:柏树湾泉(-9.84

  19. Fractionated Mercury Isotopes in Fish: The Effects of Nuclear Mass, Spin, and Volume

    Science.gov (United States)

    Das, R.; Odom, A. L.

    2007-12-01

    Mercury is long known as a common environmental contaminant. In methylated form it is even more toxic and the methylation process is facilitated by microbial activities. Methyl mercury easily crosses cell membrane and accumulates in soft tissues of fishes and finally biomagnifies with increasing trophic levels. Natural variations in the isotopic composition of mercury have been reported and such variations have emphasized mass dependent fractionations, while theory and laboratory experiments indicate that mass-independent isotopic fractionation (MIF) effects are likely to be found as well. This study focuses on the MIF of mercury isotopes in the soft tissues of fishes. Samples include both fresh water and marine fish, from different continents and oceans. Approximately 1 gm of fish soft tissue was dissolved in 5 ml of conc. aqua regia for 24 hrs and filtered through a ¬¬¬100 μm filter paper and diluted with DI water. Hg is measured as a gaseous phase generated by reduction of the sample with SnCl2 in a continuous- flow cold-vapor generator connected to a Thermo-Finnigan Neptune MC-ICPMS. To minimize instrumental fractionation isotope ratios were measured by sample standard bracketing and reported as δ‰ relative to NIST SRM 3133 Hg standard where δAHg = [(A Hg/202Hg)sample/(A Hg/202Hg)NIST313] -1 ×1000‰. In this study we have measured the isotope ratios 198Hg/202Hg, 199Hg/202Hg, 200Hg/202Hg, 201Hg/202Hg and 204Hg/202Hg. In all the fish samples δ198Hg, δ200Hg, δ202Hg, δ204Hg define a mass- dependent fractionation sequence, where as the δ199Hg and δ201Hg depart from the mass- dependent fractionation line and indicate an excess of the odd-N isotopes. The magnitude of the deviation (ΔAHg where A=199 or 201) as obtained by difference between the measured δ199Hg and δ201Hg of the samples and the value obtained by linear scaling defined by the even-N isotopes ranges from approximately 0.2 ‰ to 3‰. The ratios of Δ199Hg /Δ201Hg range from 0.8 to 1

  20. The cobalt radioactive isotopes in environment; Les isotopes radioactifs du cobalt dans l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    For the year 1993 the total activity released in cobalt is 69 GBq for the whole of nuclear power plants. The part of activity in cobalt for La Hague in 1993 is 8 GBq of {sup 58}Co and 2 GBq of {sup 60}Co. The radioactive isotopes released by nuclear power plants or the reprocessing plant of La Hague under liquid effluents are shared by half between {sup 58}Co and {sup 60}Co. The exposure to sealed sources is the most important risk for the cobalt. The risk of acute exposure can associate a local irradiation of several decades of grays inducing a radiological burns, deep burn to treat in surgery by resection or graft even amputation. A global irradiation of organism for several grays induces an acute irradiation syndrome, often serious. At long term the stochastic effects are represented by leukemia and radio-induced cancers. The increase of probability of their occurrence is 1% by sievert. We must remind that the natural spontaneous probability is 25%. (N.C.)

  1. Phosphorus dynamics in soils irrigated with reclaimed waste water or fresh water - A study using oxygen isotopic composition of phosphate

    Science.gov (United States)

    Zohar, I.; Shaviv, A.; Young, M.; Kendall, C.; Silva, S.; Paytan, A.

    2010-01-01

    Transformations of phosphate (Pi) in different soil fractions were tracked using the stable isotopic composition of oxygen in phosphate (??18Op) and Pi concentrations. Clay soil from Israel was treated with either reclaimed waste water (secondary, low grade) or with fresh water amended with a chemical fertilizer of a known isotopic signature. Changes of ??18Op and Pi within different soil fractions, during a month of incubation, elucidate biogeochemical processes in the soil, revealing the biological and the chemical transformation impacting the various P pools. P in the soil solution is affected primarily by enzymatic activity that yields isotopic equilibrium with the water molecules in the soil solution. The dissolved P interacts rapidly with the loosely bound P (extracted by bicarbonate). The oxides and mineral P fractions (extracted by NaOH and HCl, respectively), which are considered as relatively stable pools of P, also exhibited isotopic alterations in the first two weeks after P application, likely related to the activity of microbial populations associated with soil surfaces. Specifically, isotopic depletion which could result from organic P mineralization was followed by isotopic enrichment which could result from preferential biological uptake of depleted P from the mineralized pool. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with reclaimed waste water compared to the fertilizer treated soil. ?? 2010 Elsevier B.V.

  2. Release of Pu isotopes from the Fukushima Daiichi Nuclear Power Plant accident to the marine environment was negligible.

    Science.gov (United States)

    Bu, Wenting; Fukuda, Miho; Zheng, Jian; Aono, Tatsuo; Ishimaru, Takashi; Kanda, Jota; Yang, Guosheng; Tagami, Keiko; Uchida, Shigeo; Guo, Qiuju; Yamada, Masatoshi

    2014-08-19

    Atmospheric deposition of Pu isotopes from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has been observed in the terrestrial environment around the FDNPP site; however, their deposition in the marine environment has not been studied. The possible contamination of Pu in the marine environment has attracted great scientific and public concern. To fully understand this possible contamination of Pu isotopes from the FDNPP accident to the marine environment, we collected marine sediment core samples within the 30 km zone around the FDNPP site in the western North Pacific about two years after the accident. Pu isotopes ((239)Pu, (240)Pu, and (241)Pu) and radiocesium isotopes ((134)Cs and (137)Cs) in the samples were determined. The high activities of radiocesium and the (134)Cs/(137)Cs activity ratios with values around 1 (decay corrected to 15 March 2011) suggested that these samples were contaminated by the FDNPP accident-released radionuclides. However, the activities of (239+240)Pu and (241)Pu were low compared with the background level before the FDNPP accident. The Pu atom ratios ((240)Pu/(239)Pu and (241)Pu/(239)Pu) suggested that global fallout and the pacific proving ground (PPG) close-in fallout are the main sources for Pu contamination in the marine sediments. As Pu isotopes are particle-reactive and they can be easily incorporated with the marine sediments, we concluded that the release of Pu isotopes from the FDNPP accident to the marine environment was negligible.

  3. Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of amino sugars in marine sediment

    Directory of Open Access Journals (Sweden)

    R. Zhu

    2014-01-01

    Full Text Available Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e. equivalent to ~ 8 ng of amino sugar carbon. Our results obtained from δ13C analysis of amino sugars in selected marine sediment samples showed that muramic acid had isotopic imprints from indigenous bacterial activities, whereas glucosamine and galactosamine were mainly derived from organic detritus. The analysis of stable carbon isotopic compositions of amino sugars opens a promising window for the investigation of microbial metabolisms in marine sediments and the deep marine biosphere.

  4. Oxygen isotope variations in granulite-grade iron formations: constraints on oxygen diffusion and retrograde isotopic exchange

    Science.gov (United States)

    Sharp, Z.D.; O'Neil, J.R.; Essene, E.J.

    1988-01-01

    The oxygen isotope ratios of various minerals were measured in a granulite-grade iron formation in the Wind River Range, Wyoming. Estimates of temperature and pressure for the terrane using well calibrated geothermometers and geobarometers are 730??50?? C and 5.5??0.5 kbar. The mineral constraints on fluid compositions in the iron formation during retrogression require either very CO2-rich fluids or no fluid at all. In the iron formation, isotopic temperature estimates from quartz-magnetite fractionations are controlled by the proximity to the enclosing granitic gneiss, and range from 500?? C (??qz - mt=10.0???) within 2-3 meters of the orthogneiss contact to 600?? C (??qz - mt=8.0???) farther from the contact. Temperature estimates from other isotopic thermometers are in good agreement with those derived from the quartz-magnetite fractionations. During prograde metamorphism, the isotopic composition of the iron formation was lowered by the infiltration of an external fluid. Equilibrium was achieved over tens of meters. Closed-system retrograde exchange is consistent with the nearly constant whole-rock ??18Owr value of 8.0??0.6???. The greater ??qz-mt values in the iron formation near the orthogneiss contact are most likely due to a lower oxygen blocking temperature related to greater exchange-ability of deformed minerals at the contact. Cooling rates required to preserve the quartz-magnetite fractionations in the central portion of the iron formation are unreasonably high (???800?? C/Ma). In order to preserve the 600?? C isotopic temperature, the diffusion coefficient D (for ??-quartz) should be two orders of magnitude lower than the experimentally determined value of 2.5??10-16 cm2/s at 833 K. There are no values for the activation energy (Q) and pre-exponential diffusion coefficient (D0), consistent with the experimentally determined values, that will result in reasonable cooling rates for the Wind River iron formation. The discrepancy between the diffusion

  5. Determination of plutonium content in high burnup pressurized water reactor fuel samples and its use for isotope correlations for isotopic composition of plutonium.

    Science.gov (United States)

    Joe, Kihsoo; Jeon, Young-Shin; Han, Sun-Ho; Lee, Chang-Heon; Ha, Yeong-Keong; Song, Kyuseok

    2012-06-01

    The content of plutonium isotopes in high burnup pressurized water reactor fuel samples was examined using both alpha spectrometry and mass spectrometry after anion exchange separation. The measured values were compared with results calculated by the ORIGEN-2 code. On average, the ratios (m/c) of the measured values (m) over the calculated values (c) were 1.22±0.16 for (238)Pu, 1.02±0.14 for (239)Pu, 1.08±0.06 for (240)Pu, 1.06±0.16 for (241)Pu, and 1.13±0.08 for (242)Pu. Using the Pu data obtained in this work, correlations were derived between the alpha activity ratios of (238)Pu/((239)Pu+(240)Pu), the alpha specific activities of Pu, and the atom % abundances of the Pu isotopes. Using these correlations, the atom % abundances of the plutonium isotopes in the target samples were calculated. These calculated results agreed within a range from 2 to 8% of the experimentally derived values according to the isotopes of plutonium.

  6. Myths of Isotopic Reference Materials Busted

    Science.gov (United States)

    Coplen, T.

    2007-12-01

    During the past several years, the determination of the isotopic abundances of elements including H, Li, B, C, N, O, Mg, Si, S, Cl, Ca, Cr, Fe, Cu, Zn, Tl, and Se has substantially increased because of expanded use in hydrology, environmental studies, microbiology, forensic investigations, atmospheric investigations, oceanography, etc. Improvements in instrumentation enable increasingly precise isotope-amount-ratio measurements in these fields, but these improvements in precision commonly do not lead to improvements in accuracy because of the lack or improper use of isotopic reference materials. When properly used, these critically important materials enable any laboratory worldwide to measure the same homogeneous sample and report the same isotopic abundance within analytical uncertainty. For example, for stable isotopic analysis of gaseous hydrogen samples, the agreement among 36 laboratories worldwide before normalization to any hydrogen gas reference material was 11.8 per mill. After normalization to anchors (gaseous H isotopic reference materials) at each end of the delta H-2 scale, the agreement was 0.85 per mill, an improvement of more than an order of magnitude. Consistency of delta C-13 measurements often can be improved by nearly 50 percent by anchoring the delta C-13 scale with two isotopic reference materials differing substantially in C-13 mole fraction, namely NBS 19 calcite and L-SVEC lithium carbonate. Agreement of delta C-13 values of four expert laboratories analyzing USGS40 L- glutamic acid by CF-IRMS methods improved from 0.084 to 0.015 per mill with use of the two scale anchors (NBS 19 and L-SVEC). Solid oxygen isotopic reference materials (IAEA-600 caffeine, IAEA-601 and IAEA-602 benzoic acids, IAEA-NO-3, USGS32, USGS34, and USGS35 nitrates, NBS-127, IAEA-SO-5, and IAEA-SO-6 barium sulfates) are poorly calibrated. Calibrating these solids to the VSMOW-SLAP reference water scale has been very difficult because both the solids and reference

  7. Stable isotopes in Lithuanian bioarcheological material

    Science.gov (United States)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

    Investigation of bioarcheological material of ancient human populations allows us to understand the subsistence behavior associated with various adaptations to the environment. Feeding habits are essential to the survival and growth of ancient populations. Stable isotope analysis is accepted tool in paleodiet (Schutkowski et al, 1999) and paleoenvironmental (Zernitskaya et al, 2014) studies. However, stable isotopes can be useful not only in investigating human feeding habits but also in describing social and cultural structure of the past populations (Le Huray and Schutkowski, 2005). Only few stable isotope investigations have been performed before in Lithuanian region suggesting a quite uniform diet between males and females and protein intake from freshwater fish and animal protein. Previously, stable isotope analysis has only been used to study a Stone Age population however, more recently studies have been conducted on Iron Age and Late medieval samples (Jacobs et al, 2009). Anyway, there was a need for more precise examination. Stable isotope analysis were performed on human bone collagen and apatite samples in this study. Data represented various ages (from 5-7th cent. to 18th cent.). Stable carbon and nitrogen isotope analysis on medieval populations indicated that individuals in studied sites in Lithuania were almost exclusively consuming C3 plants, C3 fed terrestrial animals, and some freshwater resources. Current investigation demonstrated social differences between elites and country people and is promising in paleodietary and daily life reconstruction. Acknowledgement I thank prof. dr. G. Grupe, Director of the Anthropological and Palaeoanatomical State Collection in Munich for providing the opportunity to work in her laboratory. The part of this work was funded by DAAD. Antanaitis-Jacobs, Indre, et al. "Diet in early Lithuanian prehistory and the new stable isotope evidence." Archaeologia Baltica 12 (2009): 12-30. Le Huray, Jonathan D., and Holger

  8. Fractionation behavior of chromium isotopes during coprecipitation with calcium carbonate

    DEFF Research Database (Denmark)

    Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes;

    2015-01-01

    Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenviro......Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track...

  9. Second international conference on isotopes. Conference proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, C.J. [ed.

    1997-10-01

    The Second International Conference on Isotopes (2ICI) was hosted by the Australian Nuclear Association in Sydney, NSW, Australia. The Theme of the Second Conference: Isotopes for Industry, Health and a Better Environment recognizes that isotopes have been used in these fields successfully for many years and offer prospects for increasing use in the future. The worldwide interest in the use of research reactors and accelerators and in applications of stable and radioactive isotopes, isotopic techniques and radiation in industry, agriculture, medicine, environmental studies and research in general, was considered. Other radiation issues including radiation protection and safety were also addressed. International and national overviews and subject reviews invited from leading experts were included to introduce the program of technical sessions. The invited papers were supported by contributions accepted from participants for oral and poster presentation. A Technical Exhibition was held in association with the Conference. This volume contains the foreword, technical program, the author index and of the papers (1-60) presented at the conference.

  10. Stable isotope enrichment using a plasma centrifuge

    Science.gov (United States)

    Krishnan, Mahadevan; Bures, Brian; Madden, Robert

    2012-10-01

    A primary goal of the Department of Energy's Isotope Development and Production for Research and Applications Program (Isotope Program) within the Office of Nuclear Physics (NP) is to produce isotopes that are in short supply in the U.S. and of which there exists no or insufficient domestic commercial production capability. A vacuum arc plasma centrifuge is a rigid rotor column of metal plasma in which centrifugal forces re-distribute ions radially according to their mass/charge ratio. Early work demonstrated rotation at 2 million rpm and separation of various stable isotopes. The spinning plasma column had a Gaussian flux profile, peaked on the rigid rotor axis. This work adopts a more efficient approach, with the plasma created as a hollow column, wherein the flux is concentrated at larger radii where the centrifugal action is highest. By tailoring the vacuum arc discharge geometry, the rotation rate can also be increased to ˜10 million rpm. Data from Cu, Al and other metal plasmas will be presented and discussed in light of enriched stable isotopes needed for research and medicine.

  11. CERN to start producing medical isotopes

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    A promising project that was hailed at the ICTR-PHE 2012 medical conference (see Bulletin issues 10-11/2012 and 12-13/2012) has seen the light of day at CERN. The project, known by the name of MEDICIS, will make it possible to produce a large variety of radioactive isotopes for medical research.   This image of a brain, superimposed on a drawing by Leonardo da Vinci, was taken by a PET scanner after injecting a molecule containing a positron-emitting isotope. CERN-MEDICIS will produce new isotopes for imaging which will be able to show up cancerous tissues and destroy them by emitting local radiation as the isotopes decay. In the United States, a new radium-based drug which targets bone metastases is about to go on the market. Radium, which can be brought to bear at the cell level, is a potent weapon in the fight against certain types of cancer, and is opening the way to a new form of medicine. This is the direction that CERN has decided to follow through the CERN-MEDICIS* (Medical Isotopes...

  12. Isotope Fractionation in Methane Reactions Studied by Gas Chromatography and Liquid Scintillation

    DEFF Research Database (Denmark)

    Andersen, Bertel Lohmann; Bidoglio, G.; Leip, A.

    1997-01-01

    Determination of C-14-marked methane by gas chromatography and liquid scintillation counting is shown to be useful in studies of isotope effects. Data on the specific activity is used to separate the contributions of (CH4)-C-14, and (CH4)-C-12 to the gas-chromatographic peak area. As an application...

  13. Boron and chlorine isotopic signatures of seawater in the Central Indian Ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Xiao, Y.K.; Hai, L.

    Isotopic ratios of boron and chlorine were measured in the upper 2000 m water column of the Central Indian Ridge from two tectonically active areas, one at 5°S and other at 10°S which coincided with the spreading regime of the Central Indian Ridge...

  14. Changing Ideas about the Periodic Table of Elements and Students' Alternative Concepts of Isotopes and Allotropes.

    Science.gov (United States)

    Schmidt, Hans-Jurgen; Baumgartner, Tim; Eybe, Holger

    2003-01-01

    Investigates secondary school students' concepts of isotopes and allotropes and how the concepts are linked to the Periodic Table of Elements (PTE). Questions senior high school students with multiple choice items and interviews. Shows that students actively tried to make sense of what they had experienced. (KHR)

  15. Calculation of Production and Decay of Radio Isotopes for Future Irradiation Experiments and Ion Bea

    CERN Document Server

    M. Eller, J. Lettry, R. Catherall, T. Stora

    The design of future radioactive ion beam (RIB) facilities requires the forecast of radio isotope inventory after irradiation. At CERN ISOLDE we developed a software tool that estimates the roduction and activation of materials for ISOLDE radioactive waste anagement. The tool can also be used in the design of new RIB facilities, for licensing procedures, for irradiation experiments and the estimation of production yields.

  16. A Study of the Molecular Cloud S64 with Multiple Lines of CO Isotopes

    Institute of Scientific and Technical Information of China (English)

    Lei Zhu; Yue-Fang Wu; Yue Wei

    2006-01-01

    We report on a study of the molecular cloud S64 with observations at millimeter wavelengths of multiple molecular lines of CO isotopes. A weak outflow is found, and its physical parameters are estimated. The departure of the core of S64 from the S64 HⅡ region indicates that there are still other star formation activities in that region.

  17. Stable isotope paleoaltimetry and the evolution of landscapes and life

    Science.gov (United States)

    Mulch, Andreas

    2016-01-01

    Reconstructing topography of our planet not only advances our knowledge of the geodynamic processes that shape the Earth's surface; equally important it adds a key element towards understanding long-term continental moisture transport, atmospheric circulation and the distribution of biomes and biodiversity. Stable isotope paleoaltimetry exploits systematic decreases in the oxygen (δ18O) or hydrogen (δD) isotopic composition of precipitation along a mountain front when the interaction of topography and advected moist air masses induces orographic precipitation. These changes in δ18O or δD can be recovered from the geologic record and recent geochemical and modeling advances allow a broad range of proxy materials to be evaluated. Over the last 10 yr stable isotope paleoaltimetry has witnessed rapidly expanding research activities and has produced a broad array of fascinating tectonic and geomorphologic studies many of which have concentrated on determining the elevation history of continental plateau regions. These single-site studies have greatly expanded what used to be very sparse global paleoaltimetric data. The challenge now lies in disentangling the surface uplift component from the impact of climate change on δ18O and δD in precipitation. The robustness of stable isotope paleoaltimetry can be enhanced when high-elevation δ18O or δD data are referenced against low-elevation sites that track climate-modulated sea level δ18O or δD of precipitation through time (' δ- δ approach'). Analysis of central Andean paleosols documents that differences in δ18O of soil carbonate between the Subandean foreland and the Bolivian Altiplano are small between 11 and 7 Ma but rise rapidly to ca. 2.9‰ after 7 Ma, corroborating the magnitude of late Miocene change in δ18O on the Altiplano. Future advances in stable isotope paleoaltimetry will greatly benefit from addressing four key challenges: (1) Identifying topographically-induced changes in atmospheric

  18. Present status and future prospects of industrial applications of isotopes in Bangladesh

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, M.D.S. [Bangladesh Atomic Energy Commission, Ramna Dhaka (Bangladesh)

    1997-10-01

    Ionising radiation is used for quality assurance and quality control of many industrial products. Bangladesh is actively working on the industrial application of isotopes in the fields of non-destructive testing (NDT) of material, nuclear analytical technique, radiation technology, tracer technology through the participation in the UNDP/IAEA/RCA Project for Asia and the Pacific on the industrial application of isotopes and radiation technology. Bangladesh is developing NDT technology to such an extent and standard that the country is attaining self-reliance in this field for service and human resource development and the foreign dependence is becoming greatly reduced. Examples of recent achievements are given

  19. The labeling of unsaturated γ-hydroxybutyric acid by heavy isotopes of hydrogen: iridium complex-mediated H/D exchange by C─H bond activation vs reduction by boro-deuterides/tritides.

    Science.gov (United States)

    Marek, Aleš; Pedersen, Martin H F; Vogensen, Stine B; Clausen, Rasmus P; Frølund, Bente; Elbert, Tomáš

    2016-10-01

    3-Hydroxycyclopent-1-ene-1-carboxylic acid (HOCPCA (1)) is a potent ligand for high-affinity γ-hydroxybutyric acid binding sites in the central nervous system. Various approaches to the introduction of a hydrogen label onto the HOCPCA skeleton are reported. The outcomes of the feasible C─H activation of olefin carbon (C-2) by iridium catalyst are compared with the reduction of the carbonyl group (C-3) by freshly prepared borodeuterides. The most efficient iridium catalysts proved to be Kerr bulky phosphine N-heterocyclic species providing outstanding deuterium enrichment (up to 91%) in a short period of time. The highest deuterium enrichment (>99%) was achieved through the reduction of ketone precursor 2 by lithium trimethoxyborodeuteride. Hence, analogical conditions were used for the tritiation experiment. [(3) H]-HOCPCA selectively labeled on the position C-3 was synthetized with radiochemical purity >99%, an isolated yield of 637 mCi and specific activity = 28.9 Ci/mmol.

  20. Actinides record, power calculations and activity for present isotopes in the spent fuel of a BWR; Historial de actinidos y calculos de potencia y actividad para isotopos presentes en el combustible gastado de un BWR

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez C, P.; Ramirez S, J. R.; Lucatero, M. A., E-mail: pastor.enriquez@inin.gob.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2012-10-15

    The administration of spent fuel is one of the more important stages of the nuclear fuel cycle, and this has become a problem of supreme importance in countries that possess nuclear reactors. Due to this in this work, the study on the actinides record and present fission products to the discharge of the irradiated fuel in a light water reactor type BWR is shown, to quantify the power and activity that emit to the discharge and during the cooling time. The analysis was realized on a fuel assembly type 10 x 10 with an enrichment average of 3.69 wt % in U-235 and the assembly simulation assumes four cycles of operation of 18 months each one and presents an exposition of 47 G Wd/Tm to the discharge. The module OrigenArp of the Scale 6 code is the computation tool used for the assembly simulation and to obtain the results on the actinides record presents to the fuel discharge. The study covers the following points: a) Obtaining of the plutonium vector used in the fuel production of mixed oxides, and b) Power calculation and activity for present actinides to the discharge. The results presented in this work, correspond at the same time immediate of discharge (0 years) and to a cooling stage in the irradiated fuel pool (5 years). (Author)

  1. Natural thorium isotopes in marine sediment core off Labuan port

    Energy Technology Data Exchange (ETDEWEB)

    Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.; Mohamed, C. A. R. [School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600, Bangi, Selangor (Malaysia)

    2014-02-12

    Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on {sup 228}Th/{sup 232}Th model. The results suggest the {sup 230}Th and {sup 232}Th might be originated from terrestrial sedimentary rock while {sup 228}Th originated by authigenic origin. High ratio value of {sup 230}Th/{sup 232}Th detected at the top surface sediment indicates the increasing of {sup 230}Th at the recent years which might be contributed from the anthropogenic sources. The sedimentation rate of core sediment from Labuan Port was successfully estimated by using {sup 228}Th/{sup 232}Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.

  2. Natural thorium isotopes in marine sediment core off Labuan port

    Science.gov (United States)

    Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.; Mohamed, C. A. R.

    2014-02-01

    Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on 228Th/232Th model. The results suggest the 230Th and 232Th might be originated from terrestrial sedimentary rock while 228Th originated by authigenic origin. High ratio value of 230Th/232Th detected at the top surface sediment indicates the increasing of 230Th at the recent years which might be contributed from the anthropogenic sources. The sedimentation rate of core sediment from Labuan Port was successfully estimated by using 228Th/232Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.

  3. Isotope analysis in the transmission electron microscope

    CERN Document Server

    Susi, Toma; Argentero, Giacomo; Leuthner, Gregor T; Pennycook, Timothy J; Mangler, Clemens; Meyer, Jannik C; Kotakoski, Jani

    2016-01-01

    The {\\AA}ngstr\\"om-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either $^{12}$C or $^{13}$C and describe the process using a quantum mechanical model of lattice vibrations coupled with density functional theory simulations. We then test our spatial resolution in a mixed sample by ejecting individual atoms from nanoscale areas spanning an interface region that is far from atomically sharp, mapping the isotope concentration with a precision better than 20%. Although we use a scanning instrument, our method should be applicable to any atomic resolution transmission electron microscope and to other low-dimensional materials.

  4. Strontium isotope stratigraphy of the Pelotas Basin

    Energy Technology Data Exchange (ETDEWEB)

    Zerfass, Geise de Santana dos Anjos, E-mail: geise.zerfass@petrobras.com.br [Petroleo Brasileiro S.A. (PETROBRAS/CENPES/PDGEO/BPA), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas e Desenvolvimento Leopoldo Americo Miguez de Mello; Chemale Junior, Farid, E-mail: fchemale@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Instituto de Geociencias; Moura, Candido Augusto Veloso, E-mail: candido@ufpa.br [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Centro de Geociencias. Dept. de Geoquimica e Petrologia; Costa, Karen Badaraco, E-mail: karen.costa@usp.br [Instituto Oceanografico, Sao Paulo, SP (Brazil); Kawashita, Koji, E-mail: koji@usp.br [Unversidade de Sao Paulo (USP), SP (Brazil). Centro de Pesquisas Geocronologicas

    2014-07-01

    Strontium isotope data were obtained from foraminifera shells of the Pelotas Basin Tertiary deposits to facilitate the refinement of the chronostratigraphic framework of this section. This represents the first approach to the acquisition of numerical ages for these strata. Strontium isotope stratigraphy allowed the identification of eight depositional hiatuses in the Eocene-Pliocene section, here classified as disconformities and a condensed section. The reconnaissance of depositional gaps based on confident age assignments represents an important advance considering the remarkably low chronostratigraphic resolution in the Cenozoic section of the Pelotas Basin. The recognition of hiatuses that match hiatuses is based on biostratigraphic data, as well as on global events. Furthermore, a substantial increase in the sedimentation rate of the upper Miocene section was identified. Paleotemperature and productivity trends were identified based on oxygen and carbon isotope data from the Oligocene-Miocene section, which are coherent with worldwide events, indicating the environmental conditions during sedimentation. (author)

  5. Laser spectroscopy of neutron deficient Sn isotopes

    CERN Multimedia

    We propose to study the ground state properties of neutron-deficient Sn isotopes towards the doubly-magic nucleus $^{100}$Sn. Nuclear spins, changes in the rms charge radii and electromagnetic moments of $^{101-121}$Sn will be measured by laser spectroscopy using the CRIS experimental beam line. These ground-state properties will help to clarify the evolution of nuclear structure properties approaching the $\\textit{N = Z =}$ 50 shell closures. The Sn isotopic chain is currently the frontier for the application of state-of-the-art ab-initio calculations. Our knowledge of the nuclear structure of the Sn isotopes will set a benchmark for the advances of many-body methods, and will provide an important test for modern descriptions of the nuclear force.

  6. Iron isotope systematics of the Skaergaard intrusion

    DEFF Research Database (Denmark)

    Lesher, Charles; Lundstrom, C.C.; Barfod, Gry

    crystallization on non-traditional stable isotope systems, particularly iron. FeTi oxide minerals (titanomagnetite and ilmenite) appear after ~60% of the magma had solidified. This was a significant event affecting the liquid line of descent and potentially accompanied by iron isotope fractionation. Here we...... report the results of a broad study of the iron isotope compositions of gabbros within the layered and upper border series of the Skaergaard intrusion, pegmatite and granophyre associated with these gabbroic rocks, and the sandwich horizon thought to represent the product of extreme differentiation and....../or liquid immiscibility. Forty-eight whole rock samples from well-constrained stratigraphic levels in the intrusion were crushed, powdered and dissolved, followed by iron separation by ion chromatography. Purified solutions were analyzed by MC- ICPMS in high-resolution mode using the sample-std bracket...

  7. Isotopes in the Arctic atmospheric water cycle

    Science.gov (United States)

    Bonne, Jean-Louis; Werner, Martin; Meyer, Hanno; Kipfstuhl, Sepp; Rabe, Benjamin; Behrens, Melanie; Schönicke, Lutz; Steen Larsen, Hans Christian; Masson-Delmotte, Valérie

    2016-04-01

    The ISO-ARC project aims at documenting the Arctic atmospheric hydrological cycle, by assessing the imprint of the marine boundary conditions (e.g. temperature variations, circulation changes, or meltwater input) to the isotopic composition of the atmospheric water cycle (H218O and HDO) with a focus on North Atlantic and Arctic oceans. For this purpose, two continuous monitoring water vapour stable isotopes cavity ring-down spectrometers have been installed in July 2015: on-board the Polarstern research vessel and in the Siberian Lena delta Samoylov research station (N 72° 22', E 126° 29'). The Polarstern measurements cover the summer 2015 Arctic campaign from July to mid-October, including six weeks in the Fram Strait region in July- August, followed by a campaign reaching the North Pole and a transect from the Norwegian Sea to the North Sea. These vapour observations are completed by water isotopic measurements in samples from the surface ocean water for Polarstern and from precipitation in Samoylov and Tiksi (120 km south-east of the station). A custom-made designed automatic calibration system has been implemented in a comparable manner for both vapour instruments, based on the injection of different liquid water standards, which are completely vaporised in dry air at high temperature. Subsequent humidity level can be adjusted from 2000 to at least 30000 ppm. For a better resilience, an independent calibration system has been added on the Samoylov instrument, allowing measurements of one standard at humidity levels ranging from 2000 to 15000 ppm: dry air is introduced in a tank containing a large amount of liquid water standard, undergoing evaporation under a controlled environment. The measurement protocol includes an automatic calibration every 25 hours. First instrument characterisation experiments depict a significant isotope-humidity effect at low humidity, dependant on the isotopic composition of the standard. For ambient air, our first isotope

  8. Analysing Groundwater Using the 13C Isotope

    Science.gov (United States)

    Awad, Sadek

    The stable isotope of the carbon atom (13C) give information about the type of the mineralisation of the groundwater existing during the water seepage and about the recharge conditions of the groundwater. The concentration of the CO2(aq.) dissolved during the infiltration of the water through the soil's layers has an effect on the mineralisation of this water. The type of the photosynthesis's cycle (C-3 or C-4 carbon cycle) can have a very important role to determine the conditions (closed or open system) of the mineralisation of groundwater. The isotope 13C of the dissolved CO2 in water give us a certain information about the origin and the area of pollution of water. The proportion of the biogenic carbon and its percentage in the mineralisation of groundwater is determined by using the isotope 13C.

  9. Stable isotope dilution assays in mycotoxin analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rychlik, Michael; Asam, Stefan [Universitaet Muenchen, Lehrstuhl fuer Lebensmittelchemie der Technischen, Garching (Germany)

    2008-01-15

    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis. (orig.)

  10. Stable isotope dilution assays in mycotoxin analysis.

    Science.gov (United States)

    Rychlik, Michael; Asam, Stefan

    2008-01-01

    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis.

  11. Carbon isotope geochemistry in the Yalujiang estuary

    Institute of Scientific and Technical Information of China (English)

    吴莹; 张经

    2001-01-01

    The distribution of particulate organic carbon (POC) along the lower reaches is similar between the dry season and the flood season in the Yalujiang Estuary, North China. However, the values of particulate organic carbon of the upperstream in the dry season are one magnitude lower than the concentrations in the flood season. Stable carbon isotope ratios have been used to study the sources of particulate organic carbon in the Yalujiang Estuary. The isotopic composition of POC shows a range from -23.1‰ to -29.4‰ with a little seasonal variation. The isotopic evidence indicates that the POC in the Yalujiang Estuary is predominantly of terrestrial origin rather than a result of in situ plankton. The study of the ratio of POC: Chla shows that the turbidity maximum plays an important role in POC cycle in the Yalujiang Estuary. Organic detritus and soil erosion are the main contributions to POC in the turbidity maximum, especially in the flood season.

  12. Sr-O isotope systematics in the Campi Flegrei magma systems

    Science.gov (United States)

    Wörner, Gerhard; Iovine, Raffaella; Carmine Mazzeo, Fabio; D'Antonio, Massimo; Arienzo, Ilenia; Civetta, Lucia; Orsi, Giovanni

    2016-04-01

    range mostly between 7 and 10 ‰ VSMOW, maximum and minimum values reach from ~11 to ~6 ‰ VSMOW. Our data obtained so far show compositions that are very different from typical mantle values and that span a very large range towards heavy δ18O values compared to other magmatic compositions from the Italian Peninsula. We compare our clinopyroxene and olivine data with published clinopyroxene and olivine O-isotope data from other Italian volcanic centers (Alban Hills, Mts. Ernici, Ischia, Mt. Vesuvius, Aeolian Islands, Tuscany and Sardinia) and from subduction zones worldwide (Kamchatka, Lesser Antilles, Indonesia and Central Andean ignimbrites). Distinct trends and sources are recognized: (1) serpentinized mantle (Kamchatka), (2) sediment-enrichment in the mantle source (Indonesia, Vesuvius), (3) magma assimilation by old radiogenic continental crust (Alban Hills, Tuscany, Ischia), (4) assimilation by mafic crust (Andes). Sr-O-isotope values of Campi Flegrei and Vesuvius magmas fall on the same vertical trend in Sr-O isotope space that deviates profoundly from all other subduction-related magmas. This indicates that magmas are derived from (a) a mantle source variably modified by pelagic sediments (as for Vesuvius) that were later (b) assimilated by highly δ18O-enriched crustal material that did not further significantly affect the Sr-isotope composition. From Sr-O isotope relations, this crustal signal could be introduced through interaction with Mesozoic limestone and/or low-T altered volcanic material from previous volcanic activity in the Campi Flegrei caldera.

  13. Stable silver isotope fractionation in the natural transformation process of silver nanoparticles.

    Science.gov (United States)

    Lu, Dawei; Liu, Qian; Zhang, Tuoya; Cai, Yong; Yin, Yongguang; Jiang, Guibin

    2016-08-01

    Nanoparticles in the environment can form by natural processes or be released due to human activities. Owing to limited analytical methods, the behaviour of nanoparticles in the natural environment is poorly understood and until now they have only been described by the variations in the nanoparticle size or the concentration of the element of interest. Here we show that by using inductively coupled plasma mass spectrometry to measure silver (Ag) isotope ratios it is possible to understand the transformation processes of silver nanoparticles (AgNPs) in the environment. We found that the formation and dissolution of AgNPs under natural conditions caused significant variations in the ratio of natural Ag isotopes ((107)Ag and (109)Ag) with an isotopic enrichment factor (ε) up to 0.86‰. Furthermore, we show that engineered AgNPs have distinctly different isotope fractionation effects to their naturally formed counterparts. Further studies will be needed to understand whether isotope analysis can be used to reveal the sources of AgNPs in the environment.

  14. Anharmonicity effects in impurity-vacancy centers in diamond revealed by isotopic shifts and optical measurements

    Science.gov (United States)

    Ekimov, E. A.; Krivobok, V. S.; Lyapin, S. G.; Sherin, P. S.; Gavva, V. A.; Kondrin, M. V.

    2017-03-01

    We studied isotopically enriched nano- and microdiamonds with optically active GeV- centers synthesized at high pressures and high temperatures in nonmetallic growth systems. The influence of isotopic composition on optical properties has been thoroughly investigated by photoluminescence-excitation (PLE) and photoluminescence (PL) spectroscopy to get insight into the nature and electronic structure of this color center. We have demonstrated that the large frequency defect (difference between oscillation frequencies in the ground and excited electronic states) does bring about large discrepancy between PLE and PL spectra and comparatively high isotopic shift of the zero phonon line. Both effects seem to be rather common to split-vacancy centers (for example SiV-), where the frequency defect reaches record high values. Isotopic substitution of carbon atoms in the diamond lattice results in even larger shifts, which are only partially accounted for by a redistribution of electron density caused by the volume change of the diamond lattice. It was shown that the vibronic frequency in this case does not depend on the mass of carbon atoms. The greatest part of this isotopic shift is due to anharmonicity effects, which constitute a substantial part of vibronic frequency observed in this center. The exact physical mechanism, which leads to significant enhancement of anharmonicity on substitution of 12C to 13C, is yet to be clarified.

  15. Application of isotopic and hydro-geochemical methods in identifying sources of mine inrushing water

    Institute of Scientific and Technical Information of China (English)

    Dou Huiping; Ma Zhiyuan; Cao Haidong; Liu Feng; Hu Weiwei; Li Ting

    2011-01-01

    Isotopic and hydro-geochemical surveys were carried out to identify the source of mine inrushing water at the #73003 face in the Laohutai Mine.Based on the analysis of isotopes and hydro-chemical features of surface water,groundwater from different levels and the inrushing water,a special relationship between water at the #73003 face and cretaceous water has been found.The results show that the isotopic and hydro-chemical features of the inrushing water are completely different from those of other groundwater bodies,except for the cretaceous water.The isotopic and hydrochemical characteristics of cretaceous water are similar to the inrushing water of the #73003 face,which aided with obtaining the evidence for the possible source of the inrushing water at the #73003 face.The isotope calculations show that the inrushing water at the #73003 face is a mixture of cretaceous water and Quaternary water,water from the cretaceous conglomerate is the main source,accounting for 67% of the inrushing water,while the Quaternary water accounts for 33%.The conclusion is also supported by a study of inrushing-water channels and an active fault near the inrushing-water plot on the #73003 face.

  16. Richland five-year O2 R&D program, other isotopes

    Energy Technology Data Exchange (ETDEWEB)

    1968-06-30

    The Hanford production complex is potentially capable of producing and processing a wide variety of isotopes. Some of these have been identified as specific R & D missions (i.e., plutonium-238, transplutonium elements and tritium), and the technical programs supporting these efforts are described elsewhere in this series of Five-Year Program documents. Capability to produce other isotopes has been demonstrated in the successful production of `clean` uranium-233, in the recovery of large quantities of selected fission products, and in the development of process technology for polonium-210. Active R & D programs are underway to improve the technical bases for producing these isotopes, and for demonstrating the capability of producing others. Formerly, several R & D missions were identified and conducted to define the technical factors for initiating production of these isotopes. Either the efforts on these missions have declined because of decreased emphasis (polonium-210) or because of the advanced status of the technology (uranium-233), or the efforts have generally been modest (cobalt-60). These several efforts are now combined into one R & D mission, other isotopes, and they are described in the following pages of this document.

  17. Stable silver isotope fractionation in the natural transformation process of silver nanoparticles

    Science.gov (United States)

    Lu, Dawei; Liu, Qian; Zhang, Tuoya; Cai, Yong; Yin, Yongguang; Jiang, Guibin

    2016-08-01

    Nanoparticles in the environment can form by natural processes or be released due to human activities. Owing to limited analytical methods, the behaviour of nanoparticles in the natural environment is poorly understood and until now they have only been described by the variations in the nanoparticle size or the concentration of the element of interest. Here we show that by using inductively coupled plasma mass spectrometry to measure silver (Ag) isotope ratios it is possible to understand the transformation processes of silver nanoparticles (AgNPs) in the environment. We found that the formation and dissolution of AgNPs under natural conditions caused significant variations in the ratio of natural Ag isotopes (107Ag and 109Ag) with an isotopic enrichment factor (ε) up to 0.86‰. Furthermore, we show that engineered AgNPs have distinctly different isotope fractionation effects to their naturally formed counterparts. Further studies will be needed to understand whether isotope analysis can be used to reveal the sources of AgNPs in the environment.

  18. Zinc isotope fractionation during magmatic differentiation and the isotopic composition of the bulk Earth

    Science.gov (United States)

    Chen, Heng; Savage, Paul S.; Teng, Fang-Zehn; Helz, Rosalind T.; Moynier, Frédéric

    2013-01-01

    he zinc stable isotope system has been successfully applied to many and varied fields in geochemistry, but to date it is still not completely clear how this isotope system is affected by igneous processes. In order to evaluate the potential application of Zn isotopes as a proxy for planetary differentiation and volatile history, it is important to constrain the magnitude of Zn isotopic fractionation induced by magmatic differentiation. In this study we present high-precision Zn isotope analyses of two sets of chemically diverse, cogenetic samples from Kilauea Iki lava lake, Hawaii, and Hekla volcano, Iceland, which both show clear evidence of having undergone variable and significant degrees of magmatic differentiation. The Kilauea Iki samples display small but resolvable variations in Zn isotope composition (0.26‰66Zn66Zn defined as the per mille deviation of a sample's 66Zn/64Zn compositional ratio from the JMC-Lyon standard), with the most differentiated lithologies exhibiting more positive δ66Zn values. This fractionation is likely a result of the crystallization of olivine and/or Fe–Ti oxides, which can both host Zn in their crystal structures. Samples from Hekla have a similar range of isotopic variation (0.22‰66Zn66Zn=0.28±0.05‰ (2s.d.).

  19. The power of integrating kinetic isotope effects into the formalism of the Michaelis-Menten equation.

    Science.gov (United States)

    Klinman, Judith P

    2014-01-01

    The final arbiter of enzyme mechanism is the ability to establish and test a kinetic mechanism. Isotope effects play a major role in expanding the scope and insight derived from the Michaelis-Menten equation. The integration of isotope effects into the formalism of the Michaelis-Menten equation began in the 1970s and has continued until the present. This review discusses a family of eukaryotic copper proteins, including dopamine β-monooxygenase, tyramine β-monooxygenase and peptidylglycine α-amidating enzyme, which are responsible for the synthesis of neuroactive compounds, norepinephrine, octopamine and C-terminally carboxamidated peptides, respectively. The review highlights the results of studies showing how combining kinetic isotope effects with initial rate parameters permits the evaluation of: (a) the order of substrate binding to multisubstrate enzymes; (b) the magnitude of individual rate constants in complex, multistep reactions; (c) the identification of chemical intermediates; and (d) the role of nonclassical (tunnelling) behaviour in C-H activation.

  20. La138/139 Isotopic Data and Neutron Fluences for Oklo RZ10 Reactor

    CERN Document Server

    Gould, C R; 10.1103/PhysRevC.86.027601

    2012-01-01

    Recent years have seen a renewed interest in the Oklo phenomenon, particularly in relation to the study of time variation of the fine structure constant. The neutron fluence is one of the crucial parameters for Oklo reactors. Several approaches to its determination were elaborated in the past. We consider whether it possible to use the present isotopic La138/139 data for RZ10 as an additional indicator of neutron fluences in the active cores of the reactors. We calculate the dependence of the Oklo La138 abundance on neutron fluence and elemental lanthanum concentration. The neutron fluence in RZ10 can be deduced from lanthanum isotopic data, but requires reliable data on the primordial elemental abundance. Conversely, if the fluence is known, the isotope ratio provides information on the primordial lanthanum abundance that is not otherwise easily determined.

  1. La-138/139 isotopic data and neutron fluences for Oklo RZ10 reactor

    Science.gov (United States)

    Gould, C. R.; Sharapov, E. I.

    2012-08-01

    Background: Recent years have seen a renewed interest in the Oklo phenomenon, particularly in relation to the study of time variation of the fine structure constant α. The neutron fluence is one of the crucial parameters for Oklo reactors. Several approaches to its determination were elaborated in the past.Purpose: We consider whether it is possible to use the present isotopic 138La-139La data for RZ10 as an additional indicator of neutron fluences in the active cores of the reactors.Results: We calculate the dependence of the Oklo 138La abundance on neutron fluence and elemental lanthanum concentration.Conclusion: The neutron fluence in RZ10 can be deduced from lanthanum isotopic data, but requires reliable data on the primordial elemental abundance. Conversely, if the fluence is known, the isotope ratio provides information on the primordial lanthanum abundance that is not otherwise easily determined.

  2. Prospects and Challenges in tropical isotope dendroclimatology

    Science.gov (United States)

    Evans, M. N.; Anchukaitis, K. J.; White, S. R.; Ektvedt, T. M.; Penniston, R. C.; Rheaume, M. M.; Bowman, D. M.

    2008-12-01

    We review a stable isotope-based approach to the development, modeling, interpretation, and analysis of hydrometeorological estimates from tropical trees. The strategy overcomes the common problem of missing, intermittent or non-annual ring structure in tropical trees by relying instead on the observation of the annual wet-dry seasonality typical to tropical environments as mirrored in the oxygen isotopic composition of wood-derived α-cellulose. We explore regions for which forward modeling of the proxy system would expect us to resolve hydrometeorological variations associated with the El Niño-Southern Oscillation (ENSO) phenomenon, rather than being limited to regions with tree species or environments producing verifiable annual ring chronologies. A modified protocol allows for rapid, simple and non-toxic micro-extraction of pure α-cellulose, which is isotopically indistinguishable from that produced by more classical means. We describe a new reactor for the pyrolysis of α-cellulose in an induction heater, which permits isotopic analysis of α-cellulose samples as small as 30μg, and as many as 100 automated sample analyses per day. A forward model adapted for tropical environments can be used to test and refine the interpretation of the isotopic data, and to predict locales for which we should be able to maximize the paleoclimatic potential of future sample collections. We have found the modeled isotopic chronometer and raingage in agreement with independent chronological controls in a variety of environments and tree species in Costa Rica, Indonesia, Brazil, Peru and Australia. Development of long hydrometeorological records from the terrestrial tropics is underway not only by our group, but by a growing number of collaborators and colleagues. Together we should be able to build a network of paleoprecipitation records and better understand the linkages between tropical surface ocean temperatures and large-scale drought.

  3. Titan's Isotopic Menagerie: The Cassini CIRS Perspective

    Science.gov (United States)

    Nixon, Conor A.; Achterberg, R. K.; Bezard, B.; Bjoraker, G. L.; Coustenis, A.; de Kok, R.; Flasar, F. M.; Hewagama, T.; Irwin, P. G. J.; Jennings, D. E.; Jolly, A.; Romani, P. N.; Teanby, N. A.; Vinatier, S.; CIRS Team

    2008-09-01

    Saturn's long-mysterious moon Titan is gradually yielding up its secrets under the intense scrutiny of the Cassini spacecraft, which has just completed a 4-year prime mission including 45 close flybys of the giant satellite. We here focus on the isotopic composition of the stratosphere, which since Voyager 1 in 1980 has been known to comprise a surprisingly rich mixture of hydrocarbons, nitriles and several oxygen species. These molecules are now understood to originate in the upper atmosphere by chemical processes initiated by the dissociation of the most abundant native species - methane and nitrogen - with some oxygen added from externally-supplied water. Measurements of isotopic ratios in these compounds are important and can provide valuable information on the formation and evolution of Titan's atmosphere. E.g. Chemical processes can cause isotopic fractionation via the 'kinetic isotope effect' (KIE). Cassini's Composite Infrared Spectrometer (CIRS), which is sensitive to thermal infrared radiation from 10-1500 cm-1 (7-1000 micron), is an ideal tool for measuring molecular concentrations and can distinguish between isotopologues due to the shifts in the molecular bands. CIRS has now identified at least eleven isotopologue species in our spectra, with multiple new detections in the past year (13CO2, CO18O, HC13CCCN). CIRS has measured the ratios 12C/13C in a total of seven species, D/H in two species, and 14N/15N and 16O/18O each in one species - the best measurement so far of the important ratio 16O/18O on Titan (346±110). In this presentation we will summarize all our results to date on isotopic ratios, including comparison with Huygens GCMS and other determinations, a discussion of possible isotopic separation in hydrocarbon chains, and formation/evolution implications of these measurements for Titan.

  4. Hitting the moving target: modelling ontogenetic shifts with stable isotopes reveals the importance of isotopic turnover.

    Science.gov (United States)

    Hertz, Eric; Trudel, Marc; El-Sabaawi, Rana; Tucker, Strahan; Dower, John F; Beacham, Terry D; Edwards, Andrew M; Mazumder, Asit

    2016-05-01

    Ontogenetic niche shifts are widely prevalent in nature and are important in shaping the structure and dynamics of ecosystems. Stable isotope analysis is a powerful tool to assess these shifts, with δ(15) N providing a measure of trophic level and δ(13) C a measure of energy source. Previous applications of stable isotopes to study ontogenetic niche shifts have not considered the appreciable time lag between diet and consumer tissue associated with isotopic turnover. These time lags introduce significant complexity into field studies of ontogenetic niche shifts. Juvenile Chinook salmon (Oncorhynchus tshawytscha) migrate from freshwater to marine ecosystems and shift their diet from feeding primarily on invertebrates to feeding primarily on fish. This dual ontogenetic habitat and diet shift, in addition to the long time lag associated with isotopic turnover, suggests that there is potential for a disconnect between the prey sources that juvenile salmon are consuming, and the inferred prey sources from stable isotopes. We developed a model that considered ontogenetic niche shifts and time lags associated with isotopic turnover, and compared this 'ontogeny' model to one that considered only isotopic turnover. We used a Bayesian framework to explicitly account for parameter uncertainty. Data showed overwhelming support for the ontogeny model relative to the isotopic turnover model. Estimated variables from best model fits indicate that the ontogeny model predicts a much greater reliance on fish prey than does the stomach content data. Overall, we found that this method of quantifying ontogenetic niche shifts effectively accounted for both isotopic turnover and ontogenetic diet shifts; a finding that could be widely applicable to a variety of systems.

  5. Novel PEFC Application for Deuterium Isotope Separation

    Directory of Open Access Journals (Sweden)

    Hisayoshi Matsushima

    2017-03-01

    Full Text Available The use of a polymer electrolyte fuel cell (PEFC with a Nafion membrane for isotopic separation of deuterium (D was investigated. Mass analysis at the cathode side indicated that D diffused through the membrane and participated in an isotope exchange reaction. The exchange of D with protium (H in H2O was facilitated by a Pt catalyst. The anodic data showed that the separation efficiency was dependent on the D concentration in the source gas, whereby the water produced during the operation of the PEFC was more enriched in D as the D concentration of the source gas was increased.

  6. Precision Mass Measurement of Argon Isotopes

    CERN Multimedia

    Lunney, D

    2002-01-01

    % IS388\\\\ \\\\ A precision mass measurement of the neutron-deficient isotopes $^{32,33,34}$Ar is proposed. Mass values of these isotopes are of importance for: a) a stringent test of the Isobaric-Multiplet- Mass-Equation, b) a verification of the correctness of calculated charge-dependent corrections as used in super-allowed $\\beta$- decay studies aiming at a test of the CVC hypothesis, and c) the determination of the kinematics in electron-neutrino correlation experiments searching for scalar currents in weak interaction. The measurements will be carried out with the ISOLTRAP Penning trap mass spectrometer.

  7. Isotope separation and advanced manufacturing technology

    Science.gov (United States)

    Carpenter, J.; Kan, T.

    This is the fourth issue of a semiannual report for the Isotope Separation and Advanced Materials Manufacturing (ISAM) Technology Program at Lawrence Livermore National Laboratory. Primary objectives include: (1) the Uranium Atomic Vapor Laser Isotope Separation (UAVLIS) process, which is being developed and prepared for deployment as an advanced uranium enrichment capability; (2) Advanced manufacturing technologies, which include industrial laser and E-beam material processing and new manufacturing technologies for uranium, plutonium, and other strategically important materials in support of DOE and other national applications. This report features progress in the ISAM Program from October 1993 through March 1994.

  8. OXYGEN ISOTOPE FRACTION ATION IN URANIUM OXIDES

    Institute of Scientific and Technical Information of China (English)

    郑永飞

    1995-01-01

    Thermodynamic oxygen isotope factors for uranium oxides have been calculated by means of the modified increment method.The sequence of 18O-enrichment in the uranium oxides with respect to the common rock-forming minerals is predicted as follows:spinelisotopic geothermometry of uranium ores when pairing with other gangue minerals in hydrothermal uranium deposits.

  9. Iron isotopes in an Archean ocean analogue

    Science.gov (United States)

    Busigny, Vincent; Planavsky, Noah J.; Jézéquel, Didier; Crowe, Sean; Louvat, Pascale; Moureau, Julien; Viollier, Eric; Lyons, Timothy W.

    2014-05-01

    Iron isotopes have been extensively used to trace the history of microbial metabolisms and the redox evolution of the oceans. Archean sedimentary rocks display greater variability in iron isotope ratios and more markedly negative values than those deposited in the Proterozoic and Phanerozoic. This increased variability has been linked to changes in either water column iron cycling or the extent of benthic microbial iron reduction through time. We tested these contrasting scenarios through a detailed study of anoxic and ferruginous Lac Pavin (France), which can serve as a modern analogue of the Archean ocean. A depth-profile in the water column of Lac Pavin shows a remarkable increase in dissolved Fe concentration (0.1-1200 μM) and δ56Fe values (-2.14‰ to +0.31‰) across the oxic-anoxic boundary to the lake bottom. The largest Fe isotope variability is found at the redox boundary and is related to partial oxidation of dissolved ferrous iron, leaving the residual Fe enriched in light isotopes. The analysis of four sediment cores collected along a lateral profile (one in the oxic layer, one at the redox boundary, one in the anoxic zone, and one at the bottom of the lake) indicates that bulk sediments, porewaters, and reactive Fe mostly have δ56Fe values near 0.0 ± 0.2‰, similar to detrital iron. In contrast, pyrite δ56Fe values in sub-chemocline cores (60, 65, and 92 m) are highly variable and show significant deviations from the detrital iron isotope composition (δ56Fepyrite between -1.51‰ and +0.09‰; average -0.93‰). Importantly, the pyrite δ56Fe values mirror the δ56Fe of dissolved iron at the redox boundary—where near quantitative sulfate and sulfide drawdown occurs—suggesting limited iron isotope fractionation during iron sulfide formation. This finding has important implications for the Archean environment. Specifically, this work suggests that in a ferruginous system, most of the Fe isotope variability observed in sedimentary pyrites can

  10. Isotopic abundance in atom trap trace analysis

    Science.gov (United States)

    Lu, Zheng-Tian; Hu, Shiu-Ming; Jiang, Wei; Mueller, Peter

    2014-03-18

    A method and system for detecting ratios and amounts of isotopes of noble gases. The method and system is constructed to be able to measure noble gas isotopes in water and ice, which helps reveal the geological age of the samples and understand their movements. The method and system uses a combination of a cooled discharge source, a beam collimator, a beam slower and magneto-optic trap with a laser to apply resonance frequency energy to the noble gas to be quenched and detected.

  11. The magnesium isotope record of cave carbonate archives

    Directory of Open Access Journals (Sweden)

    S. Riechelmann

    2012-11-01

    Full Text Available Here we explore the potential of magnesium (δ26Mg isotope time-series data as continental climate proxies in speleothem calcite archives. For this purpose, a total of six Pleistocene and Holocene stalagmites from caves in Germany, Morocco and Peru and two flowstones from a cave in Austria were investigated. These caves represent the semi-arid to arid (Morocco, the warm-temperate (Germany, the equatorial-humid (Peru and the cold-humid (Austria climate zones. Changes in the calcite magnesium isotope signature with time are compared against carbon and oxygen isotope records from these speleothems. Similar to other proxies, the non-trivial interaction of a number of environmental, equilibrium and disequilibrium processes governs the δ26Mg fractionation in continental settings. These include the different sources of magnesium isotopes such as rainwater or snow as well as soil and host rock, soil zone biogenic activity, shifts in silicate versus carbonate weathering ratios and residence time of water in the soil and karst zone. Pleistocene stalagmites from Morocco show the lowest mean δ26Mg values (GDA: −4.26 ± 0.07‰ and HK3: −4.17 ± 0.15‰, and the data are well explained in terms of changes in aridity over time. The Pleistocene to Holocene stalagmites from Peru show the highest mean value of all stalagmites (NC-A and NC-B δ26Mg: −3.96 ± 0.04‰ but only minor variations in Mg-isotope composition, which is consistent with the rather stable equatorial climate at this site. Holocene stalagmites from Germany (AH-1 mean δ26Mg: −4.01 ± 0.07‰; BU 4 mean δ26Mg: −4.20 ± 0.10‰ suggest changes in outside air temperature was the principal driver rather than rainfall amount. The alpine Pleistocene flowstones from Austria (SPA 52: −3.00 ± 0.73‰; SPA 59: −3.70 ± 0.43‰ are affected by glacial versus interglacial climate change with outside air temperature

  12. The magnesium isotope record of cave carbonate archives

    Directory of Open Access Journals (Sweden)

    S. Riechelmann

    2012-05-01

    Full Text Available Here we explore the potential of time-series magnesium (δ26Mg isotope data as continental climate proxies in speleothem calcite archives. For this purpose, a total of six Pleistocene and Holocene stalagmites from caves in Germany, Morocco and Peru and two flowstones from a cave in Austria were investigated. These caves represent the semi-arid to arid (Morocco, the warm-temperate (Germany, the equatorial-humid (Peru and the cold-humid (Austria climate zones. Changes in the calcite magnesium isotope signature with time are placed against carbon and oxygen isotope records from these speleothems. Similar to other proxies, the non-trivial interaction of a number of environmental, equilibrium and non-equilibrium processes governs the δ26Mg fractionation in continental settings. These include the different sources of magnesium isotopes such as rain water or snow as well as soil and hostrock, soil zone biogenic activity, shifts in silicate versus carbonate weathering ratios and residence time of water in the soil and karst zone. Pleistocene stalagmites from Morocco show the lowest mean δ26Mg values (GDA: −4.26 ± 0.07 ‰ and HK3: −4.17 ± 0.15 ‰ and the data are well explained in terms of changes in aridity over time. The Pleistocene to Holocene stalagmites from Peru show the highest mean value (NC-A and NC-B δ26Mg: −3.96 ± 0.04 ‰ but only minor variations in Mg-isotope composition, which is in concert with the rather stable equatorial climate at this site. Holocene stalagmites from Germany (AH-1 mean δ26Mg: −4.01 ± 0.07 ‰; BU 4 mean δ26Mg: −4.20 ± 0.10 ‰ record changes in outside air temperature as driving factor rather than rainfall amount. The alpine Pleistocene flowstones from Austria (SPA 52: −3.00 ± 0.73 ‰; SPA 59: −3.70 ± 0.43 ‰ are affected by glacial versus interglacial climate change with outside air temperature affecting soil zone activity

  13. Distribution and isotopic composition of uranium in lower Nueces River, Nueces Bay and Corpus Christi Bay, Texas

    Science.gov (United States)

    Holmes, Charles W.; Slade, Elizabeth Ann

    1972-01-01

    The uranium concentration and isotopic composition of water and suspended sediment from the Nueces River, Nueces Bay and Corpus Christi Bay were determined by alpha-spectroscopy. The average dissolved uranium concentration and radioactivity ratio (U234/U238) of Nueces River water were determined to be 2.44 µg/1 and 1.15 respectively. Water from a tributary of the Nueces River, Cayamon Creek, was found to contain an average dissolved uranium concentration of 42.8 µg/1 with an isotopic radioactivity ratio of 1.56. Close inspection of the lateral concentration and isotopic activity ratio of uranium revealed an increase below the confluence of Cayamon Creek with the Nueces River. A model was derived based on equations used in isotopic dilution analysis, which predicts these increases within analytical error. This model may be useful in future studies to locate anomalous uranium within the hydrologic environment.

  14. Features of adsorbed radioactive chemical elements and their isotopes distribution in iodine air filters AU-1500 at nuclear power plants

    CERN Document Server

    Neklyudov, I M; Dikiy, N P; Ledenyov, O P; Lyashko, Yu V

    2013-01-01

    The main aim of research is to investigate the physical features of spatial distribution of the adsorbed radioactive chemical elements and their isotopes in the granular filtering medium in the iodine air filters of the type of AU1500 in the forced exhaust ventilation systems at the nuclear power plant. The gamma activation analysis method is applied to accurately characterize the distribution of the adsorbed radioactive chemical elements and their isotopes in the granular filtering medium in the AU1500 iodine air filter after its long term operation at the nuclear power plant. The typical spectrum of the detected chemical elements and their isotopes in the AU1500 iodine air filter, which was exposed to the bremsstrahlung gamma quantum irradiation, produced by the accelerating electrons in the tantalum target, are obtained. The spatial distributions of the detected chemical element 127I and some other chemical elements and their isotopes in the layer of absorber, which was made of the cylindrical coal granule...

  15. Hydrograph separation using stable isotopes: Review and evaluation

    Science.gov (United States)

    Klaus, J.; McDonnell, J. J.

    2013-11-01

    We reviewed isotope hydrograph separation studies.We examine methods, applications, and limitations.We summarize factors that control the event/pre-event water contributions.We outline new possible research avenues in isotope hydrograph separation.

  16. Method for production of an isotopically enriched compound

    Science.gov (United States)

    Watrous, Matthew G.

    2012-12-11

    A method is presented for producing and isolating an isotopically enriched compound of a desired isotope from a parent radionuclide. The method includes forming, or placing, a precipitate containing a parent radionuclide of the desired daughter isotope in a first reaction zone and allowing sufficient time for the parent to decay into the desired gaseous daughter radioisotope. The method further contemplates collecting the desired daughter isotope as a solid in a second reaction zone through the application of temperatures below the freezing point of the desired isotope to a second reaction zone that is connected to the first reaction zone. Specifically, a method is presented for producing isotopically enriched compounds of xenon, including the radioactive isotope Xe-131m and the stable isotope Xe-131.

  17. Isotopic compositions of boron in sediments and their implications

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Yingkai, X.

    The abundance and isotopic compositions of boron in sediments from the salt lakes of Qaidam Basin, China have been determined by thermal ionization mass spectrometry of cesium borate. The results show large variations in the isotopic compositions...

  18. The three-isotope method for equilibrium isotope fractionation factor determination: Unfounded optimism

    Science.gov (United States)

    Cao, X.; Hayles, J. A.; Bao, H.

    2015-12-01

    The equilibrium isotope fractionation factor α is a fundamental parameter in stable isotope geochemistry. Although equilibrium α can be determined by theoretical calculation or by measurement of natural samples, direct laboratory experiments are ultimately required to verify those results. The attainment of a true exchange equilibrium in experiments is often difficult, but three methods have been devised and used to ensure that an equilibrium α has been obtained in an isotope exchange experiment. These are the two-directional method, partial-exchange method, and three-isotope method. Of these, the three-isotope method is thought to be the most rigorous. Using water-water exchange as a basic unit, we have developed a set of complex exchange models to study when and why the three-isotope method may work well or not. We found that the method cannot promise to lead to an equilibrium α before the kinetic complexity of the specific exchange experiment is known. An equilibrium point in δ17O-δ18O space can be reached only when all of the isotope exchange pathways are fully reversible, i.e. there is no mass loss at any instant, and the forward and backward reactions share the same pathway. If the exchange pathways are not fully reversible, steady state may be reached, but a steady state α can be very different from the equilibrium α. Our results validated the earlier warning that the trajectory for three-isotope evolution in δ17O-δ18O space may be a distinctly curved line or contain more than one straight line due to the non-fully reversible isotope exchange reactions. The three-isotope method for equilibrium α determination is not as rigorous or as promising as it may seem. Instead, the trajectory of three-isotope evolution provides detailed insights into the kinetics of isotope exchange between compounds. If multiple components exist in the exchange system, the δ17O-δ18O evolving trajectory would be more complex.

  19. Cr isotope fractionation in metal-mineral-microbe interactions

    Science.gov (United States)

    Zhang, Qiong; Porcelli, Don; Thompson, Ian; Amor, Ken; Galer, Stephen

    2016-04-01

    Microbes interact with metals and minerals in the environments, altering their physical and chemical state whilst in turn the metals and minerals affect microbial growth, activity and survival. The interactions between Cr, Fe minerals and bacteria were investigated in this study. Cr(VI) reduction experiments by two iron-reducing bacteria, Pseudomonas fluorescens LB 300 and Shewanella oneidensis MR 1, in the presence of two iron oxide minerals, goethite and hematite, were conducted. Both minerals were found to inhibit the Cr(VI) reduction rate by Pseudomonas fluorescens LB 300 but accelerated Shewanella oneidensis MR 1. The Cr isotopic fractionation factor generated by both bacteria was mostly independent of the presence of the minerals, except for hematite with Pseudomonas fluorescens LB 300, where the ɛ was much higher. Aqueous Fe(III) in the solution did not have any detectable impact on either bacterial Cr reduction rates or the isotopic fractionation factors, indicating that the reduction of Cr(VI) occurred prior to that of Fe(III). The presence of aqueous Fe(II) induced a very fast abiotic reduction of Cr, but had little impact on the bacterial Cr reduction rates or its isotope fractionations. The evidence suggests that the different impact that Fe minerals had on the bacteria were related to the way they attached to the minerals and the difference in the reduction mechanism. SEM images confirmed that the attachment of Pseudomonas fluorescens LB 300 on the mineral surfaces were much more tightly packed than that of Shewanella oneidensis MR 1, so reducing mineral-metal interactions.

  20. Occultism and the atom: the curious story of isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Jeff

    2003-09-01

    The routes to scientific discovery are sometimes strange. We are all familiar with the story of Newton and the falling apple, or with Friedrich Kekule's dream of a snake biting its own tail that led to the discovery of benzene's ring-like structure. But such stories - engaging though they might be - are often mythical. They serve a function in science, emphasizing individual psychology and the flash of inspiration from a heroic scientific genius, over the more routine and collective aspects of scientific work. Romanticism aside, however, the history of science - like Orwell's Big Brother state - usually writes and rewrites history to remove inconvenient facts, mistakes and idiosyncrasies, leaving only a rationalized path to our present knowledge, or what historians sometimes call 'whig' history. In so doing, it not only distorts the actual course of historical events but also gives a misleadingly simplistic picture of the richness of scientific activity and the interactions between science and broader culture. In the history of physics, for example, the discovery of isotopes by Frederick Soddy and Francis Aston is usually cast as part of a linear sequence of discoveries in atomic and nuclear physics. The story, we are told, began with the discovery of radioactivity in the 1890s, continued with the discovery of the nucleus (1911), isotopes (1913), wave mechanics (1920s) and the neutron (1932), before leading to nuclear fission (1938) and, ultimately, the atomic bomb (1945). In the September issue of Physics World Jeff Hughes describes how the history of isotopes was rewritten and why. (U.K.)

  1. Modern Freshwater Microbialites of Cuatro Ciénegas, Mexico. I: Metagenomic and Stable Isotopic Analyses to Assess Microbial Community Structure and Function

    Science.gov (United States)

    Breitbart, M.; Hollander, D.; Nitti, A.; van Mooy, B.; Siefert, J.; Souza, V.

    2010-04-01

    This study utilized metagenomic and stable isotopic analyses to examine the microorganisms and chemical processes leading to carbonate precipitation in the actively-accreting freshwater microbialites from Rio Mesquites in Cuatro Ciénegas, Mexico.

  2. Stable isotope deltas: tiny, yet robust signatures in nature.

    Science.gov (United States)

    Brand, Willi A; Coplen, Tyler B

    2012-09-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg

  3. Determination of fission gas yields from isotope ratios

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg

    1983-01-01

    This paper describes a method of calculating the actual fission yield of Kr and Xe in nuclear fuel including the effect of neutron capture reactions and decay. The bases for this calculation are the cumulative yields (ref. 1) of Kr and Xe isotopes (or pairs of isotopes) which are unaffected...... by neutron capture reactions, and measured Kr and Xe isotope ratios. Also the burnup contribution from the different fissile heavy isotopes must be known in order to get accurate fission gas yields....

  4. Stable isotope deltas: Tiny, yet robust signatures in nature

    Science.gov (United States)

    Brand, Willi A.; Coplen, Tyler B.

    2012-01-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including 14C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. 13C, 2H, and 18O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as−25 per mil can be written as−25 mUr (or−2.5 cUr or−0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg ‘units’ are easily included (e.g. either+0.015 ‰ or+15 per meg

  5. Impact of root-induced mobilization of zinc on stable Zn isotope variation in the soil-plant system.

    Science.gov (United States)

    Houben, David; Sonnet, Philippe; Tricot, Guillaume; Mattielli, Nadine; Couder, Eléonore; Opfergelt, Sophie

    2014-07-15

    Stable Zn isotopes are increasingly used to trace the source of metal pollution in the environment and to gain a better understanding of the biogeochemical cycle of Zn. In this work, we investigated the effect of plants on Zn isotope fractionation in the soil-plant system of the surface horizon of two Zn-rich Technosols (pH 6.73-7.51, total Zn concentration = 9470-56600 mg kg(-1)). In a column experiment, the presence of Agrostis capillaris L. significantly increased the mobilization of Zn from soil to leachate, predominantly as a result of root-induced soil acidification. The zinc isotope compositions of plants and leachates indicated that the Zn uptake by A. capillaris did not fractionate Zn isotopes as compared to the leachates. Within the plant, heavier Zn isotopes were preferentially retained in roots (Δ66Znroot - shoot=+0.24 to +0.40 ‰). More importantly, the Zn released in leachates due to root-induced mobilization was isotopically heavier than the Zn released in the absence of plants (Δ66Zn=+0.16 to +0.18 ‰). This indicates that the rhizosphere activity of A. capillaris mobilized Zn from another pool than the one that spontaneously releases Zn upon contact with the percolating solution. Mobilization of Zn by the roots might thus exert a stronger influence on the Zn isotope composition in the soil solution than the Zn uptake by the plant. This study highlights the key role of the rhizosphere activity in Zn release in soil and demonstrates that stable Zn isotopes provide a useful proxy for the detection of Zn mobilization in soil-plant systems.

  6. Evaluation of Speleothem Oxygen Isotope Fractionation from a Tropical Cave on the Island of Guam

    Science.gov (United States)

    Moore, M. W.; Hardt, B. F.; Banner, J. L.; Jenson, J. W.

    2013-12-01

    Recent studies in the tropics apply oxygen isotope variations in speleothems as proxies for changes in past hydroclimate, yet little work has been done to study the modern tropical cave environment. Oxygen isotope time series in speleothems are commonly used to interpret past climate based on the assumption of equilibrium fractionation. When re-constructing paleoclimate, there are limited tools available to assess potential non-equilibrium isotope effects. One approach is to test for agreement of oxygen isotope values between parallel-milled tracks from a stalagmite. A stalagmite collected from Jinapsan Cave on the island of Guam supports the argument for equilibrium as multiple overlapping transects along the growth axis show consistent replication. However, to fully evaluate the fractionation processes relating to calcite growth, we have also studied the relationship between modern drip water and modern speleothem calcite. To accomplish this, we collected monthly dripwater samples and deployed artificial substrates under active drips to measure calcite growth rates and to assess the state of isotopic equilibrium between speleothem calcite and drip water. We evaluate the processes controlling the δ18O values of calcite formed on substrates relative to values for the dripwater feeding the site of the speleothem in Jinapsan Cave. The studied drip site shows seasonal variability in dripwater δ18O of ~1‰, with more negative composition occurring during the wet season. The δ18O of the substrate calcite sampled at the point of first growth (analogous to the growth axis in a speleothem) also shows a seasonal cycle of about 1‰, yet the values are more positive than predicted by the equilibrium equation of Kim & O'Neil 1997. In addition, carbon and oxygen isotopic composition between substrates strongly covary. Correlation of carbon and oxygen isotopes between substrates at the point of first growth may be explained by prior calcite precipitation. Carbon isotope

  7. Carbon allocation and carbon isotope fluxes in the plant-soil-atmosphere continuum: a review

    Science.gov (United States)

    Brüggemann, N.; Gessler, A.; Kayler, Z.; Keel, S. G.; Badeck, F.; Barthel, M.; Boeckx, P.; Buchmann, N.; Brugnoli, E.; Esperschütz, J.; Gavrichkova, O.; Ghashghaie, J.; Gomez-Casanovas, N.; Keitel, C.; Knohl, A.; Kuptz, D.; Palacio, S.; Salmon, Y.; Uchida, Y.; Bahn, M.

    2011-11-01

    The terrestrial carbon (C) cycle has received increasing interest over the past few decades, however, there is still a lack of understanding of the fate of newly assimilated C allocated within plants and to the soil, stored within ecosystems and lost to the atmosphere. Stable carbon isotope studies can give novel insights into these issues. In this review we provide an overview of an emerging picture of plant-soil-atmosphere C fluxes, as based on C isotope studies, and identify processes determining related C isotope signatures. The first part of the review focuses on isotopic fractionation processes within plants during and after photosynthesis. The second major part elaborates on plant-internal and plant-rhizosphere C allocation patterns at different time scales (diel, seasonal, interannual), including the speed of C transfer and time lags in the coupling of assimilation and respiration, as well as the magnitude and controls of plant-soil C allocation and respiratory fluxes. Plant responses to changing environmental conditions, the functional relationship between the physiological and phenological status of plants and C transfer, and interactions between C, water and nutrient dynamics are discussed. The role of the C counterflow from the rhizosphere to the aboveground parts of the plants, e.g. via CO2 dissolved in the xylem water or as xylem-transported sugars, is highlighted. The third part is centered around belowground C turnover, focusing especially on above- and belowground litter inputs, soil organic matter formation and turnover, production and loss of dissolved organic C, soil respiration and CO2 fixation by soil microbes. Furthermore, plant controls on microbial communities and activity via exudates and litter production as well as microbial community effects on C mineralization are reviewed. A further part of the paper is dedicated to physical interactions between soil CO2 and the soil matrix, such as CO2 diffusion and dissolution processes within the

  8. Understanding radioxenon isotopical ratios originating from radiopharmaceutical facilities

    Science.gov (United States)

    Saey, P. R. J.; Ringbom, A.; Bowyer, T. W.; Becker, A.; de Geer, L.-E.; Nikkinen, M.; Payne, R. F.

    2009-04-01

    It was recently shown that radiopharmaceutical facilities (RPF) are major contributors to the general background of 133Xe and other xenon isotopes both in the northern and southern hemisphere. To distinguish a nuclear explosion signal from releases from civil nuclear facilities, not only the activity concentrations but also the ratios of the four different CTBT relevant radioxenon isotopes (131mXe, 133mXe, 133Xe and 135Xe) have to be well understood. First measurements taken recently in and around two of the world's largest RPF's: NTP at Pelindaba, South Africa and IRE at Fleurus, Belgium have been presented. At both sites, also stack samples were taken in close cooperation with the facility operators. The radioxenon in Belgium could be classified in four classes: the normal European background (133Xe activity between 0 - 5 mBq/m3) on one hand and then the samples where all four isotopes were detected with 133mXe/131mXe > 1. In northern South Africa the Pelindaba RPF is in practice the sole source of radioxenon. It generated a background of 133Xe at the measurement site some 230 km to the west of the RPF of 0 - 5 mBq/m3. In the cases where the air from the Pelindaba facility reached the measurement site directly and in a short time period, the 133Xe was higher, also 135Xe was present and in some samples 133mXe as well. The ratios of the activity concentrations of 135Xe/133Xe vs. 133mXe/131mXe (Multiple Isotope Ratio Plot - MIRC) have been analysed. For both facilities, the possible theoretical ratio's for different scenarios were calculated with the information available and compared with the measurements. It was found that there is an excess of 131mXe present in the European samples compared to theoretical calculations. A similar excess has also been seen in samples measured in northern America. In South Africa, neither the environmental samples nor the stack ones contained 131mXe at measurable levels. This can probably be explained by different processes and

  9. Discovery of the actinium, thorium, protactinium, and uranium isotopes

    CERN Document Server

    Fry, C

    2012-01-01

    Currently, 31 actinium, 31 thorium, 28 protactinium, and 23 uranium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  10. Discovery of Samarium, Europium, Gadolinium, and Terbium Isotopes

    CERN Document Server

    May, E

    2012-01-01

    Currently, thirty-four samarium, thirty-four europium, thirty-one gadolinium, and thirty-one terbium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  11. Isotope separation of the Yb-168 stable isotope for low energy gamma ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun Min; Kwon, Duck Hee; Cha, Yong Ho; Lee, Ki Tae; Nam, Sung Mo; Yoo, Jaek Won; Han, Jae Min; Rhee, Yong Joo [Lab. of Quantum Optics, Korea Atomic Energy Research Institute, Taejeon (Korea, Republic of)

    2003-07-01

    We developed laser isotope separation technology of stable isotope of low melting point metals. Yb-168 can be effectively used in non-destructive testing (NDT) after it is transformed to Yb-168 by neutron irradiation in a nuclear reactor. For this application of Yb-168, the isotope purity of it should be enhanced to more than 15% from the natural abundance of 0.135%. Our isotope separation system consist of laser system, Yb vapor generating system, and photoionized particle extraction system. For the system, we developed a diode-pumped slid-state laser of high-repetition rate and 3-color dye lasers. Yb vapor was generated by heating solid Yb sample resistively. The photo-ion produced by resonance ionization were extracted by a devised extractor. We produced enriched Yb metal more than 20 mg with the abundance of 25.8% of Yb-168 in the Yb (NO{sub 3}){sub 3}.

  12. Thorium isotopes in colloidal fraction of water from San Marcos Dam, Chihuahua, Mexico

    Science.gov (United States)

    Cabral-Lares, M.; Melgoza, A.; Montero-Cabrera, M. E.; Renteria-Villalobos, M.

    2013-07-01

    The main interest of this stiidy is to assess the contents and distribution of Th-series isotopes in colloidal fraction of surface water from San Marcos dam, because the suspended particulate matter serves as transport medium for several pollutants. The aim of this work was to assess the distribution of thorium isotopes (232Th and 230Th) contained in suspended matter. Samples were taken from three surface points along the San Marcos dam: water input, midpoint, and near to dam wall. In this last point, a depth sampling was also carried out. Here, three depth points were taken at 0.4, 8 and 15 meters. To evaluate the thorium behavior in surface water, from every water sample the colloidal fraction was separated, between 1 and 0.1 μm. Thorium isotopes concentraron in samples were obtained by alpha spectrometry. Activity concentrations obtained of 232Th and 230Th in surface points ranged from 0.3 to 0.5 Bq ṡ L-1, whereas in depth points ranged from 0.4 to 3.2 Bq ṡ L-1, respectively. The results show that 230Th is in higher concentration than 232Th in colloidal fraction. This can be attributed to a preference of these colloids to adsorb uranium. Thus, the activity ratio 230Th/232Th in colloidal fraction showed values from 2.3 to 10.2. In surface points along the dam, 230Th activity concentration decreases while 232Th concentration remains constant. On the other hand, activity concentrations of both isotopes showed a pointed out enhancement with depth. The results have shown a possible lixiviation of uranium from geological substrate into the surface water and an important fractionation of thorium isotopes, which suggest that thorium is non-homogeneously distributed along San Marcos dam.

  13. Quantifying nitrogen process rates in a constructed wetland using natural abundance stable isotope signatures and stable isotope amendment experiments.

    Science.gov (United States)

    Erler, Dirk V; Eyre, Bradley D

    2010-01-01

    This study describes the spatial variability in nitrogen (N) transformation within a constructed wetland (CW) treating domestic effluent. Nitrogen cycling within the CW was driven by settlement and mineralization of particulate organic nitrogen and uptake of NO3-. The concentration of NO3- was found to decrease, as the delta15N-NO3- signature increased, as water flowed through the CW, allowing denitrification rates to be estimated on the basis of the degree of fractionation of delta15N-NO3-. Estimates of denitrification hinged on the determination of a net isotope effect (eta), which was influenced byprocesses that enrich or deplete 15NO3- (e.g., nitrification), as well as the rate constants associated with the different processes involved in denitrification (i.e., diffusion and enzyme activity). The influence of nitrification on eta was quantified; however, it remained unclear how eta varied due to variability in denitrification rate constants. A series of stable isotope amendment experiments was used to further constrain the value of eta and calculate rates of denitrification, and nitrification, within the wetland. The maximum calculated rate of denitrification was 956 +/- 187 micromol N m(-2) h(-1), and the maximum rate of nitrification was 182 +/- 28.9 micromol N m(-2) h(-1). Uptake of NO3- was quantitatively more important than denitrification throughoutthe wetland. Rates of N cycling varied spatially within thewetland, with denitrification dominating in the downstream deoxygenated region of the wetland. Studies that use fractionation of N to derive rate estimates must exercise caution when interpreting the net isotope effect. We suggest a sampling procedure for future natural abundance studies that may help improve the accuracy of N cycling rate estimates.

  14. Fast ion extraction in laser isotope separation

    Energy Technology Data Exchange (ETDEWEB)

    Hazak, G.; Gell, Y.; Boneh, Y.; Goshen, S.

    1980-10-01

    An analysis of the E x B scheme for fast ion extraction in laser isotope separation is presented. Using an analytically solvable model and a numerical simulation we have found that the scheme can meet the rather severe time and space restrictions imposed by the large cross section for charge exchange.

  15. Lasers utilizing CO/sub 2/ isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Pechenin, Y.V.; Domanov, M.S.

    1980-08-01

    The lasing spectra and energy characteristics were investigated for lasers operating with the isotopes /sup 12/C/sup 16/O/sub 2/, /sup 13/C/sup 16/O/sub 2/, /sup 12/C/sup 18/O/sub 2/, and /sup 12/C/sup 16/O/sup 18/O. It was found that the output power of a laser utilizing the CO/sub 2/ isotopes was determined by the content of a particular isotope in the carbon dioxide gas. For equal enrichments, all the isotopes investigated, with the exception of /sup 12/C/sup 16/O/sup 18/O, gave comparable output powers. The unsaturated gains were identical for the most intense transitions of the symmetric molecules; the gain was a factor of two less for the asymmetric molecule. The gain rose linearly with increasing enrichment. The ultimate specific power output, given by the product of the saturation power density and the gain, was practically independent of the enrichment.

  16. Isotope specific arbitrary material flow meter

    Energy Technology Data Exchange (ETDEWEB)

    Barty, Christopher P. J.; Post, John C.; Jones, Edwin

    2016-10-25

    A laser-based mono-energetic gamma-ray source is used to provide non-destructive and non-intrusive, quantitative determination of the absolute amount of a specific isotope contained within pipe as part of a moving fluid or quasi-fluid material stream.

  17. Soil Carbon: Compositional and Isotopic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Moran, James J.; Alexander, M. L.; Laskin, Alexander

    2016-11-01

    This is a short chapter to be included in the next edition of the Encyclopedia of Soil Science. The work here describes techniques being developed at PNNL for investigating organic carbon in soils. Techniques discussed include: laser ablation isotope ratio mass spectrometry, laser ablation aerosol mass spectrometry, and nanospray desorption electrospray ionization mass spectrometry.

  18. Heavy ion isotope resolution with polymer detectors

    OpenAIRE

    Vidal-Quadras Roca, Alejo; Ortega Girón, Manuel; Fernández Moreno, Francisco; Font Garcia, Josep Lluís; Casas Ametller, Montserrat; Baixeras Divar, Carmen; Gonzalo Cestero, Miguel

    1984-01-01

    The heavy ion mass resolution power of polymer detectors Lexan and cellulose nitrate is systematically studied both for accelerator and for cosmic ions. It is concluded that a satisfactory isotopic discrimination, better than 1 u, is hardly attainable with these detectors. Peer Reviewed

  19. 2015 Update of the Discoveries of Isotopes

    CERN Document Server

    Thoennessen, M

    2016-01-01

    The 2015 update of the discovery of nuclide project is presented. Twenty new nuclides were observed for the first time in 2015. An overall review of all previous assignments was made in order to apply the discovery criteria consistently to all elements. In addition, a list of isotopes published so far only in conference proceedings or internal reports is included.

  20. Brayton Isotope Power System (BIPS) facility specification

    Energy Technology Data Exchange (ETDEWEB)

    1976-05-31

    General requirements for the Brayton Isotope Power System (BIPS)/Ground Demonstration System (GDS) assembly and test facility are defined. The facility will include provisions for a complete test laboratory for GDS checkout, performance, and endurance testing, and a contamination-controlled area for assembly, fabrication, storage, and storage preparation of GDS components. Specifications, schedules, and drawings are included.

  1. Fingerprints of environmental stressors in three selected Slovenian gravel-bed rivers: geochemical and isotopic approach

    Science.gov (United States)

    Kanduč, Tjaša; Kocman, David; Debeljak, Barbara; Mori, Nataša

    2016-04-01

    \\vska Bistrica River pollution with nitrates was observed in lower reaches, while the other two rivers in our studies have good ecological status from chemical point of view. From isotopic composition of inorganic dissolved carbon (DIC) it can be observed that DICoriginates from dissolution of carbonates in upper reaches in the Sava and Kamni\\vska Bistrica Rivers. In the Idrijca River more degraded material is leached from the terrestrial environment. Isotopic composition of carbon of F. antipyretica in the River Sava Basin in Slovenia seasonally ranged from -45‰ to -32.9‰ and isotopic composition of nitrogen from -0.2‰ to +6.5‰Ṫhe higher isotopic composition of nitrogen of +6.5‰ found in F. antipyretica was related to agricultural activity in the watershed. The isotopic composition of carbon in heterotrophic biofilm was from +22.7 to +27.4‰ indicating the flux from terrestrial (allochtonous) compartment. The use of water geochemistry and stable C and N isotopes in our studies revealed as promising approach to better understand the processes and fluxes of carbon and nitrogen across abiotic and biotic components of undisturbed and impacted river systems.

  2. {Stable isotope probing of the physical and biological controls that influence the fate and isotopic composition of carbon derived from the terrestrial methane sink }

    Science.gov (United States)

    Maxfield, P. J.; Hornibrook, E. R. C.; Dildar, N.; Evershed, R. P.

    2009-04-01

    Methane oxidizing bacteria (Methanotrophs) occur in every soil order, and are an important sink for atmospheric CH4 in well aerated soils. The quantity of C cycled via methanotrophic bacteria in soils is globally significant (Le Mer et al., 2001) yet the fate of methane derived carbon remains largely unknown and unquantified. There is generally good agreement regarding the magnitude of the soil CH4 sink determined by methane flux measurements and process modeling. More poorly characterised aspects of the soil CH4 sink include: (i) the physical and biological controls that influence the mechanism of CH4 oxidation in soils; (ii) the fate of oxidized CH4 carbon; (iii) the proportion of C from CH4 oxidation that is sequestered as organic C or released as CO2 (iv) the magnitude of kinetic isotope effects (KIEs) associated with high affinity methanotrophy in soils and the potential influence on the stable carbon isotope composition of atmospheric CH4. This research combines multiple stable isotope analytical approaches to investigate the magnitude, mechanism and pathways of the terrestrial methane sink. Principally 13CH4 stable isotope labeling techniques (Stable isotope probing; SIP) have been used to characterize and quantify methanotrophic populations in a range of different soils (Maxfield et al., 2006). Following 13CH4-incubations soil cores were removed for compound-specific C isotope analyses. Identification and quantification of methanotrophs was effectively achieved via the analysis of 13C-labelled phospholipid fatty acids (PLFAs) to link bacterial structure and function. It was also possible to identify the predominant controls influencing the active methanotrophic populations in both grassland and woodland soils (Maxfield et al., 2008). SIP can be combined with further isotopic analyses to facilitate a broader study of methanotroph C uptake and CH4 derived C sequestration. As SIP facilitates taxonomic assignments of the soil microorganisms involved in CH4 C

  3. Iron isotope systematics in planetary reservoirs

    Science.gov (United States)

    Sossi, Paolo A.; Nebel, Oliver; Foden, John

    2016-10-01

    Iron is the only polyvalent major element, and controls reduction-oxidation (redox) reactions in a host of geologic processes and reservoirs, from the mineral- to planetary-scale, on Earth and in space. Mass transfer of Fe is often accompanied by changes in bonding environment, meaning the resultant variation in bond-strength in crystals, liquids and gases induces stable isotope fractionation, even at high temperatures. In the absence of iron exchange, electron transfer can also affect iron's valence state and calculated oxygen fugacity (fO2), however its isotope composition remains unchanged. Thus, iron isotopes are a powerful tool to investigate processes that involve mass transfer, redox reactions and changes in bonding environment in planetary systems. Primitive chondritic meteorites show remarkable isotopic homogeneity, δ57 Fe = - 0.01 ± 0.01 ‰ (2SE), over a wide range of Fe/Mg vs Ni/Mg, a proxy for fO2 in the solar nebula. In chondrites, there are iron isotope differences between metal and silicates that become more pronounced at higher metamorphic grades. However, on a planetary scale, Mars and Vesta overlap with chondrites, preserving no trace of core formation or volatile depletion on these bodies. Upon assessment of pristine lherzolites, the Bulk Silicate Earth is heavier than chondrites (δ57 Fe = + 0.05 ± 0.01 ‰; 2SE), and similar to or slightly lighter than the Moon. That the mantles of some differentiated inner solar system bodies extend to heavier compositions (+ 0.2 ‰) than chondrites may principally result from volatile depletion either at a nebular or late accretion stage. Within terrestrial silicate reservoirs, iron isotopes provide insight into petrogenetic and geodynamic processes. Partial melting of the upper mantle produces basalts that are heavier than their sources, scaling with degree of melting and driving the increasingly refractory peridotite to lighter compositions. Mid-Ocean Ridge Basalts (MORBs) are homogeneous to δ57 Fe

  4. Mass Independent Fractionation of Hg Isotopes Preserved in the Precambrian

    Science.gov (United States)

    Thibodeau, A. M.; Bergquist, B. A.; Kah, L. C.; Ono, S.; Ghosh, S.; Hazen, R. M.

    2013-12-01

    Mercury (Hg) is a photochemically active, redox-sensitive, chalcophilic metal with complex biogeochemistry that displays a wide range of mass-dependent (MDF) and mass-independent (MIF) stable isotopic fractionation. In the past decade, Hg isotopes have emerged as important tracers of both the sources and cycling of Hg in the modern environment. However, their utility as environmental proxies in ancient rocks remains largely unexplored. The potential of Hg isotopes to inform Precambrian environments derives from the observation that Hg isotopes with odd atomic mass numbers (199Hg and 201Hg) undergo large MIF by the magnetic isotope effect (MIE) and smaller MIF through the nuclear volume effect (NVE). Small MIF produced via NVE has been observed for numerous transformations and is characterized by MIF ratios (Δ199Hg/Δ201Hg) of about 1.6. Large Hg-MIF driven by MIE has been observed during photochemical transformations and is characterized by Δ199Hg/Δ201Hg ratios between 1 and 1.3. This MIF signal is sensitive to a range of environmental conditions, including the amount and type of solar radiation, the presence and type of complexing organic ligands, and the Hg/dissolved organic carbon (DOC) ratio. Thus, it is hoped that Hg-MIF signals may indirectly record changes in atmospheric composition or seawater chemistry if preserved in marine sedimentary records. Previous work has clearly demonstrated that Hg-MIF signals are preserved in Archean and Paleoproterozoic marine shales and massive sulfide deposits. Here, we present evidence that such signals are also preserved in marine shales of mid-Proterozoic age, including the ~1.3 Ga Sulky formation (Dismal Lakes Group, NW Arctic), the ~1.45 Ga Greyson Shale (Belt Basin, Montana), and the ~1.5 Ga Katalsy formation (Kypry Group, Eastern European Platform). We observe that the Greyson shale and shales within the Sulky formation yield negative Hg-MIF with Δ199Hg/Δ201Hg ratios close to 1 and that Kaltasy group sediments

  5. Thorium isotopes in human tissues

    Energy Technology Data Exchange (ETDEWEB)

    Stehney, A.F.; Lucas, H.F.

    1991-12-31

    Concentrations of {sup 232}Th and activity ratios of {sup 228}Th to {sup 232}Th and {sup 230}Th to {sup 232}Th were determined in autopsy samples from five former employees of a thorium refinery. The ranges of {sup 232}Th activity concentrations (mBq g{sup {minus}1}) were 0.17--94 in lungs, 3.9--1210 in pulmonary lymph nodes, 0.14--1.19 in bones, 0.015--0.68 in liver, 0.97--5.8 in spleen, and 0.009--0.068 in kidneys. These concentrations are 10 to 1000 times greater than have been reported for persons not occupationally exposed to Th. In most of the samples, the ratios of {sup 230}Th to {sup 232}Th and {sup 228}Th to {sup 232}Th activity at death of the subject were 0.1--0.2 and 0.2--0.4, respectively. Thorium-228 to {sup 228}Ra activity ratios ({plus_minus} standard errors) of 0.86 {plus_minus} 0.11 in lungs and 1.18 {plus_minus} 0.13 in lymph nodes of one subject were obtained by calculation from ratios of {sup 228}Th to {sup 232}Th.

  6. Assessing anthropogenic pressures on groundwater using stable OH isotopes: perspectives and issues

    Science.gov (United States)

    Negrel, Philippe; Ollivier, Patrick; Flehoc, Christine; Hube, Daniel

    2015-04-01

    Large developments of isotope hydrogeology were done and well-established techniques mainly applying stable isotopes of the water molecule (hydrogen and oxygen) are now used largely to trace water provenance but also recharge processes. New methods allow the use of non-traditional isotopes (metals, compound specific stable isotope analysis CSIA...) to trace anthropogenic pressures in surface- and groundwater. Groundwater contamination in large industrial sites may come from several origins such as leakage from tanks during the production process of chemical products, liquid storage tanks, solid end product or past accumulated product in soil which is released over the time. The understanding of the origin and the further evolution of the chemical contamination in groundwater in an industrial site issued from past or current industrial activities is essential for the industrial companies regarding their environmental policies. The objective of this study was to use with an innovative way the stable isotopes of the water molecule as a low cost tool to trace pollutant plumes in groundwater and help to a better management of contaminated industrial sites. We present data on stable isotopes O and H in an European region where electrochemistry plants occur. For confidentiality purposes, the sites remain anonymous. Present day industrial activities have a direct impact on the groundwater over the site and migration of the contaminant(s) plume out of the site is supposed. We first characterize the natural groundwater background through the O-H characterization of surface water, lakes, thermal waters and regional shallow aquifers. High and low altitude recharge can be demonstrated in the area. Secondly, we used the stable isotope of the water molecule to trace over the site the impact of the Cl-rich liquor manufacturing process. Large deuterium enrichment was evidenced in the groundwater and the high values can be related to a direct contamination of the groundwater through

  7. Reporting C-14 activities and concentrations

    NARCIS (Netherlands)

    Mook, WG; van der Plicht, J

    1999-01-01

    Three modes of reporting C-14 activities are in use, in part analogous to the internationally accepted (IAEA) conventions for stable isotopes: (1) absolute activity, the specific activity of C-14 or the activity per gram of carbon; (2) activity ratio, the ratio between the absolute activities of a s

  8. Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

    Science.gov (United States)

    Hartig, Kyle C.; Ghebregziabher, Isaac; Jovanovic, Igor

    2017-03-01

    The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is impor-tant for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament-uranium interaction points. The resulting uranium oxide emis-sion exhibits a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. The results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity.

  9. Carbon isotope ratios and isotopic correlations between components in fruit juices

    Science.gov (United States)

    Wierzchnicki, Ryszard

    2013-04-01

    Nowadays food products are defined by geographical origin, method of production and by some regulations concerning terms of their authenticity. Important data for confirm the authenticity of product are providing by isotopic methods of food control. The method checks crucial criteria which characterize the authenticity of inspected product. The European Union Regulations clearly show the tendency for application of the isotopic methods for food authenticity control (wine, honey, juice). The aim of the legislation steps is the protection of European market from possibility of the commercial frauds. Method of isotope ratio mass spectrometry is very effective tool for the use distinguishably the food products of various geographical origin. The basic problem for identification of the sample origin is the lack of databases of isotopic composition of components and information about the correlations of the data. The subject of the work was study the isotopic correlations existing between components of fruits. The chemical and instrumental methods of separation: water, sugars, organic acids and pulp from fruit were implemented. IRMS technique was used to measure isotopic composition of samples. The final results for original samples of fruits (apple, strawberry etc.) will be presented and discussed. Acknowledgement: This work was supported by the Polish Ministry of Science and Higher Education under grant NR12-0043-10/2010.

  10. Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry.

    Science.gov (United States)

    Hartig, Kyle C; Ghebregziabher, Isaac; Jovanovic, Igor

    2017-03-08

    The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is impor-tant for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament-uranium interaction points. The resulting uranium oxide emis-sion exhibits a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. The results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity.

  11. Quantifying uncertainty in stable isotope mixing models

    Science.gov (United States)

    Davis, Paul; Syme, James; Heikoop, Jeffrey; Fessenden-Rahn, Julianna; Perkins, George; Newman, Brent; Chrystal, Abbey E.; Hagerty, Shannon B.

    2015-05-01

    Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, Stable Isotope Analysis in R (SIAR), a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ15N and δ18O) but all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated

  12. Strontium-isotope stratigraphy of Enewetak Atoll

    Science.gov (United States)

    Ludwig, K. R.; Halley, R. B.; Simmons, K. R.; Peterman, Z. E.

    1988-02-01

    87Sr/86Sr ratios determined for samples from a 350 m core of Neogene lagoonal, shallow-water limestones from Enewetak Atoll display a remarkably informative trend. Like the recently published data for Deep Sea Drilling Project (DSDP) carbonates, 87Sr/86Sr at Enewetak increases monotonically but not smoothly from the early Miocene to the Pleistocene. The data show intervals of little or no change in 87Sr/86Sr, punctuated by sharp transitions to lower values toward greater core depths. The sharp transitions correlate with observed solution disconformities caused by periods of subaerial erosion, whereas the intervals of little or no change in 87Sr/86Sr correspond to intervals of rapid accumulation of shallow-water carbonate sediments. When converted to numerical ages using the published DSDP 590B trend, the best-resolved time breaks are at 282 m (12.3 to 18.2 Ma missing) and 121.6 m (3.0 to 5.3 Ma missing) below the lagoon floor. At Enewetak, Sr isotopes offer a stratigraphic resolution for these shallow-marine Neogene carbonates comparable to that of nannofossil zonation in deep-sea carbonates (0.3-3 m.y.). In addition, the correlation of times of Sr-isotope breaks at Enewetak with times of rapid Sr-isotope change in the DSDP 590B samples confirms the importance off sea-level changes in the evolution of global-marine Sr isotopes and shows that the Sr-isotope response to sea-level falls is rapid.

  13. Strontium-isotope stratigraphy of Enewetak Atoll

    Science.gov (United States)

    Ludwig, K. R.; Halley, Robert B.; Simmons, Kathleen R.; Peterman, Zell E.

    1988-01-01

    87Sr/86Sr ratios determined for samples from a 350 m core of Neogene lagoonal, shallow-water limestones from Enewetak Atoll display a remarkably informative trend. Like the recently published data for Deep Sea Drilling Project (DSDP) carbonates, 87Sr/86Sr at Enewetak increases monotonically but not smoothly from the early Miocene to the Pleistocene. The data show intervals of little or no change in 87Sr/86Sr, punctuated by sharp transitions to lower values toward greater core depths. The sharp transitions correlate with observed solution disconformities caused by periods of subaerial erosion, whereas the intervals of little or no change in 87Sr/86Sr correspond to intervals of rapid accumulation of shallow-water carbonate sediments. When converted to numerical ages using the published DSDP 590B trend, the best-resolved time breaks are at 282 m (12.3 to 18.2 Ma missing) and 121.6 m (3.0 to 5.3 Ma missing) below the lagoon floor. At Enewetak, Sr isotopes offer a stratigraphic resolution for these shallow-marine Neogene carbonates comparable to that of nannofossil zonation in deep-sea carbonates (0.3-3 m.y.). In addition, the correlation of times of Sr-isotope breaks at Enewetak with times of rapid Sr-isotope change in the DSDP 590B samples confirms the importance off sea-level changes in the evolution of global-marine Sr isotopes and shows that the Sr-isotope response to sea-level falls is rapid.

  14. Radiochemical studies of neutron deficient actinide isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Williams, K.E.

    1978-04-01

    The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, /sup 242/Bk, was produced with a cross-section of approximately 10 ..mu..b in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, ..cap alpha..xn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,..cap alpha..xn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z/sub 1/ + Z/sub 2/ = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,..cap alpha..xn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of /sup 228/Pu, /sup 230/Pu, /sup 232/Cm, or /sup 238/Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes.

  15. Isotopic evidence of early hominin diets

    Science.gov (United States)

    Sponheimer, Matt; Alemseged, Zeresenay; Cerling, Thure E.; Grine, Frederick E.; Kimbel, William H.; Leakey, Meave G.; Lee-Thorp, Julia A.; Kyalo Manthi, Fredrick; Reed, Kaye E.; Wood, Bernard A.; Wynn, Jonathan G.

    2013-06-01

    Carbon isotope studies of early hominins from southern Africa showed that their diets differed markedly from the diets of extant apes. Only recently, however, has a major influx of isotopic data from eastern Africa allowed for broad taxonomic, temporal, and regional comparisons among hominins. Before 4 Ma, hominins had diets that were dominated by C3 resources and were, in that sense, similar to extant chimpanzees. By about 3.5 Ma, multiple hominin taxa began incorporating 13C-enriched [C4 or crassulacean acid metabolism (CAM)] foods in their diets and had highly variable carbon isotope compositions which are atypical for African mammals. By about 2.5 Ma, Paranthropus in eastern Africa diverged toward C4/CAM specialization and occupied an isotopic niche unknown in catarrhine primates, except in the fossil relations of grass-eating geladas (Theropithecus gelada). At the same time, other taxa (e.g., Australopithecus africanus) continued to have highly mixed and varied C3/C4 diets. Overall, there is a trend toward greater consumption of 13C-enriched foods in early hominins over time, although this trend varies by region. Hominin carbon isotope ratios also increase with postcanine tooth area and mandibular cross-sectional area, which could indicate that these foods played a role in the evolution of australopith masticatory robusticity. The 13C-enriched resources that hominins ate remain unknown and must await additional integration of existing paleodietary proxy data and new research on the distribution, abundance, nutrition, and mechanical properties of C4 (and CAM) plants.

  16. Quantification of active infliximab in human serum with liquid chromatography-tandem mass spectrometry using a tumor necrosis factor alpha -based pre-analytical sample purification and a stable isotopic labeled infliximab bio-similar as internal standard: A target-based, sensitive and cost-effective method.

    Science.gov (United States)

    El Amrani, Mohsin; van den Broek, Marcel P H; Göbel, Camiel; van Maarseveen, Erik M

    2016-07-08

    The therapeutic monoclonal antibody Infliximab (IFX) is a widely used drug for the treatment of several inflammatory autoimmune diseases. However, approximately 10% of patients develop anti-infliximab antibodies (ATIs) rendering the treatment ineffective. Early detection of underexposure to unbound IFX would result in a timely switch of therapy which could aid in the treatment of this disease. Streptavidin coated 96 well plates were used to capture biotinylated-tumor necrosis factor -alpha (b-TNF-α), which in turn was used to selectively extract the active form of IFX in human serum. After elution, IFX was digested using trypsin and one signature peptide was selected for subsequent analysis on liquid chromatography-tandem mass spectrometry (LC-MS/MS). The internal standard used was a stable isotopic labeled IFX bio-similar. The assay was successfully validated according to European Medicines Agency (EMA) guidelines and was found to be linear in a range of 0.5-20μg/mL (r(2)=0.994). Lower limit of quantification for the assay (<20% CV) was 0.5μg/mL, requiring only 2μL of sample. Cross-validation against enzyme-linked immunosorbent assay (ELISA) resulted in a high correlation between methods (r(2)=0.95 with a ρc=0.83) and the accuracy was in line with previously published results. In conclusion, a sensitive, robust and cost-effective method was developed for the bio-analysis of IFX with LC-MS/MS by means of a target-based pre-analytical sample purification. Moreover, low volume and costs of consumables per sample promote its feasibility in (pre)clinical studies and in therapeutic drug monitoring. This method should be considered as first choice due to its accuracy and multiple degree of selectivity.

  17. Isotopic fingerprints of bacterial chemosymbiosis in the bivalve Loripes lacteus

    Science.gov (United States)

    Dreier, A.; Stannek, L.; Blumenberg, M.; Taviani, M.; Sigovini, M.; Wrede, C.; Thiel, V.; Hoppert, M.

    2012-04-01

    Metazoans with chemosynthetic bacterial endosymbionts are widespread in marine habitats and respective endosymbioses are known from seven recent animal phyla. However, little is known about endosymbioses in fossil settings and, hence, ecological significance in earth history. In the presented project, we investigate the ancient and recent bivalve fauna living at marine sedimentary oxic/anoxic interfaces. Two bivalve species collected from the same benthic environment - a Mediterranean lagoon - were studied in detail. The diet of Loripes lacteus is based on thiotrophic gill symbionts whereas Venerupis aureus is a filter feeding bivalve without symbionts. The presence of three key enzymes from sulfur oxidation (APS-reductase), carbon fixation (RubisCO) and assimilation of nitrogen (glutamine synthetase [GS]) were detected by immunofluorescence in symbionts of Loripes and/or by activity tests in living specimens. In search of biosignatures associated with thiotrophic chemosymbionts that might be suitable for detection of chemosymbiotic diets in recent and fossil bivalve shells, we analyzed the isotopic composition of shell lipids (δ13C) and the bulk organic matrix of the shell (δ13C, δ15N, δ34S). We could show that the combined δ15N and δ13C values from shell extracts are stable in subfossil (Pleistocene) bivalve specimens, as long as the isotopic data is "calibrated" with respective signatures from a filter feeding bivalve sampled from the same site or lithostratigraphic bed.

  18. Research on flow characteristics of deep groundwater by environmental isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Jun; Miyaoka, Kunihide [Tsukuba Univ., Ibaraki (Japan); Sakurai, Hideyuki; Senoo, Muneaki; Kumata, Masahiro; Mukai, Masayuki; Watanabe, Kazuo; Ouchi, Misao

    1996-01-01

    In this research, as the technique for grasping the behavior of groundwater in deep rock bed which is important as the factor of disturbing the natural barrier in the formation disposal of high level radioactive waste, the method of utilizing the environmental isotopes contained in groundwater as natural tracer was taken up, and by setting up the concrete field of investigation, through the forecast of flow by the two or three dimensional groundwater flow analysis using a computer, the planning and execution of water sampling, the analysis of various environmental isotopes, the interpretation based on those results of measurement and so on, the effectiveness of the investigation technique used was verified, and the real state of the behavior of deep groundwater in the district being studied was clarified. In this research, Imaichi alluvial fan located in northern Kanto plain was taken as the object. In fiscal year 1996, three-dimensional steady state groundwater flow simulation was carried out based on the data related to shallow groundwater and surface water systems, and the places where active groundwater flow is expected were selected, and boring will be carried out there. The analysis model and the results are reported. (K.I.)

  19. The carbon isotope composition of atmospheric CO 2 in Paris

    Science.gov (United States)

    Widory, David; Javoy, Marc

    2003-10-01

    One characteristic of air pollution in the urban environment is high CO 2 concentrations resulting from human activities. Determining the relative contributions of the different CO 2 sources can be addressed simply and elegantly by combining isotope and concentration measurements. Using this approach on atmospheric CO 2 samples collected in Paris, its suburbs and the open country provides fairly accurate conclusions. Our results show that air pollution within the first few metres above ground results basically from binary mixtures among which road traffic is the main contributor and, in particular, vehicles using unleaded gasoline (˜90% of the total). Heating sources, which account for 50% of the CO 2 input below the atmospheric inversion level, and vehicles using diesel contribute very little. Human respiration has a recognisable signature at street level under certain circumstances. The combined isotope and concentration analysis provides a sensitive tracer of local variations, even detecting the occasional prevalence of human respiration and the onset of actions in which natural gas is burnt. It also detects surprising inlets of 'clean air' (CO 2-wise) in the very centre of the city.

  20. The common property of isotope anomalies in meteorites

    Energy Technology Data Exchange (ETDEWEB)

    Robert, F. [Museum-USM 205, CNRS-UMS 2679 LEME, 75 - Paris (France)

    2004-03-01

    The treatment proposed to account for the non-mass-dependent isotopic fractionation effect observed for oxygen isotopes during the synthesis of ozone (Robert and Camy-Peyret 2001) is applied to other chemical elements. A numerical treatment to calculate isotopic reaction rate ratios is proposed. This treatment yields non-mass-dependent isotopic effects in other chemical elements, qualitatively similar to those observed in some of the high temperature minerals found in the carbonaceous meteorites. This treatment may reflect the numerical consequences of an unrecognized quantum mechanical effect, linked to a property of chemical reactions involving indistinguishable isotopes. (author)

  1. Lead isotope and trace element composition of urban soils in Mongolia

    Science.gov (United States)

    Tserenpil, Sh.; Sapkota, A.; Liu, C.-Q.; Peng, J.-H.; Liu, B.; Segebade, P. Chr.

    2016-08-01

    Lead (Pb) pollution in and around Ulaanbaatar is of national concern, given that the Mongolian capital is home to nearly half of the country's entire population. By comparison, Mongolian countryside is a pristine environment because of its sparse population and low industrial activity. The concentration of Pb in urban soils (average of 39.1 mg kg-1) was twice the values found (average 18.6 mg kg-1) in background territories (i.e., Mongolian rural sites). Furthermore, Pb contamination was examined by using Pb stable isotopic composition, and covariance of Pb isotopic ratios showed two groups between rural and urban soils as pristine and disturbed sites. The 206Pb/207Pb ratio, the most prominent fingerprint for Pb pollution, was 1.163-1.185 for the urban whereas values for rural soils (1.186-1.207) were analogue to the regional Pb isotopic signatures. Local coal sources and their combustion products, one of the potential Pb pollution sources in Ulaanbaatar, have significant radiogenic properties in terms of Pb isotopic composition and revealed an average of 1.25 for 206Pb/207Pb and 19.551 for 206Pb/204Pb ratios. Thus, contributions from coal firing activity to Pb pollution lower than it was assumed, and smaller range of these values measured in urban soils may be attributed to the mixing of less radiogenic Pb as a constituent of the leaded gasolines.

  2. Agricultural Nutrient Cycling at the Strawberry Creek Watershed: Insights Into Processes Using Stable Isotope Analysis

    Science.gov (United States)

    Thuss, E.; English, M. C.; Spoelstra, J.

    2009-05-01

    When nitrogen availability exceeds biological demand, excess nitrogen, especially nitrate, may subsequently pollute ground and surface water. Agricultural practices in Southern Ontario typically supplement soils with organic and inorganic nutrients to aid in crop development, and employ various management techniques to limit nutrient loss. Excess nitrogen has several potential fates, which are controlled by the net effects of numerous nitrogen cycling reactions in the soil that are often difficult to measure directly. Nitrogen cycling in soils is controlled in large part by soil moisture, as it affects microbial activity and soil redox conditions. Stable isotope geochemistry is a powerful tool that provides information on nitrogen sources and processes. This study uses crop nitrogen and carbon isotope ratios to provide insights into the net effects of soil nitrogen cycling and nitrogen fate. This research was conducted at the Strawberry Creek Watershed (SCW), an agricultural research watershed located between Kitchener-Waterloo and Guelph, Ontario. The SCW exhibits elevated nitrate concentrations in groundwater, tile discharge, and the stream itself. Previous isotopic work revealed that this nitrate is largely derived from chemical fertilizer and manure applications. Field-scale hydrological processes lead to areas where the fate of applied nitrogen differs, which has an isotopic effect on the residual nitrogen that is available to plants. Results of this study indicate significant patterns in the isotopic signature of plant tissue, in both temporal and spatial scales. At the plot-scale where soil conditions are similar, there is little to no variation in foliar isotope values, but at the field-scale there appears to be a significant amount of variability related to soil moisture and nitrogen loss. This relationship can potentially provide insight into ideal conditions for nitrogen uptake efficiency. Reducing agricultural nitrogen leaching to ground and surface

  3. Detrital zircon evidence for Hf isotopic evolution of granitoid crust and continental growth

    Science.gov (United States)

    Iizuka, Tsuyoshi; Komiya, Tsuyoshi; Rino, Shuji; Maruyama, Shigenori; Hirata, Takafumi

    2010-04-01

    We have determined U-Pb ages, trace element abundances and Hf isotopic compositions of approximately 1000 detrital zircon grains from the Mississippi, Congo, Yangtze and Amazon Rivers. The U-Pb isotopic data reveal the lack of >3.3 Ga zircons in the river sands, and distinct peaks at 2.7-2.5, 2.2-1.9, 1.7-1.6, 1.2-1.0, 0.9-0.4, and uniformitarian secular change in Hf isotopes of granitoid crusts; Hf isotopic compositions of granitoid crusts deviate from the mantle evolution line from about 3.3 to 2.0 Ga, the deviation declines between 2.0 and 1.3 Ga and again increases afterwards. Consideration of mantle-crust mixing models for granitoid genesis suggests that the noted isotopic trends are best explained if the rate of crust generation globally increased in two stages at around (or before) 3.3 and 1.3 Ga, whereas crustal differentiation was important in the evolution of the continental crust at 2.3-2.2 Ga and after 0.6 Ga. Reconciling the isotopic secular change in granitoid crust with that in sedimentary rocks suggests that sedimentary recycling has essentially taken place in continental settings rather than active margin settings and that the sedimentary mass significantly grew through addition of first-cycle sediments from young igneous basements, until after ˜1.3 Ga when sedimentary recycling became the dominant feature of sedimentary evolution. These findings, coupled with the lack of zircons older than 3.3 Ga in river sands, imply the emergence of large-scale continents at about 3.3 Ga with further rapid growth at around 1.3 Ga. This resulted in the major growth of the sedimentary mass between 3.3 and 1.3 Ga and the predominance of its cannibalistic recycling later.

  4. C-13 isotopic studies of the surface catalysed reactions of methane

    Energy Technology Data Exchange (ETDEWEB)

    Long, M.A.; He, S.J.X.; Adebajo, M. [University of New South Wales, Sydney, NSW (Australia). School of Chemistry

    1997-10-01

    The ability of methane to methylate aromatic compounds, which are considered to be models for coal, is being studied. Related to this reaction, but at higher temperatures, is the direct formation of benzene from methane in the presence of these catalysts. Controversy exists in the literature on the former reaction, and {sup 13}C isotope studies are being used to resolve the question. The interest in this reaction arises because the utilisation of methane, in the form of natural gas, in place of hydrogen for direct coal liquefaction would have major economic advantage. For this reason Isotope studies in this area have contributed significantly to an understanding of the methylation reactions. The paper describes experiments utilising methane{sup 13}C, which show that methylation of aromatics such as naphthalene by the methane{sup 13}C is catalysed by microporous, Cu-exchanged SAPO-5, at elevated pressures (6.8 MPa) and temperatures around 400 degree C. The mass spectrometric analysis and n.m.r. study of the isotopic composition of the products of the methylation reaction demonstrate unequivocally that methane provides the additional carbon atom for the methylated products. Thermodynamic calculations predict that the reaction is favourable at high methane pressures under these experimental conditions. The mechanism as suggested by the isotope study is discussed. The catalysts which show activity for the activation of methane for direct methylation of organic compounds, such as naphthalene, toluene, phenol and pyrene, are substituted aluminophosphate molecular sieves, EIAPO-5 (where El=Pb, Cu, Ni and Si) and a number of metal substituted zeolites. Our earlier tritium studies had shown that these catalysts will activate alkanes, at least as far as isotope hydrogen exchange reactions are concerned

  5. Resolving the stellar sources of isotopically rare presolar silicate grains through Mg and Fe isotopic analyses

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ann N.; Messenger, Scott, E-mail: lan-anh.n.nguyen@nasa.gov [Robert M. Walker Laboratory for Space Science, Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston, TX 77058 (United States)

    2014-04-01

    We conducted multi-element isotopic analyses of 11 presolar silicate grains from the Acfer 094 meteorite having unusual O isotopic compositions. Eight grains are {sup 18}O-rich, one is {sup 16}O-rich, and two are extremely {sup 17}O-rich. We constrained the grains' stellar sources by measuring their Si and Mg isotopic ratios, and also the {sup 54}Fe/{sup 56}Fe and {sup 57}Fe/{sup 56}Fe ratios for five grains. The Mg and Fe isotopic measurements were conducted after surrounding matrix grains were removed for more accurate ratios. Most of the {sup 18}O-rich silicates had anomalous Mg isotopic ratios, and their combined isotopic constraints are consistent with origins in low-mass Type II supernovae (SNe II) rather than high-metallicity stars. The isotopic ratios of the {sup 16}O-rich silicate are also consistent with an SN origin. Mixing small amounts of interior stellar material with the stellar envelope replicated all measured isotopic ratios except for {sup 29}Si/{sup 28}Si and {sup 54}Fe/{sup 56}Fe in some grains. The {sup 29}Si/{sup 28}Si ratios of all SN-derived grains are matched by doubling the {sup 29}Si yield in the Ne- and Si-burning zones. The {sup 54}Fe/{sup 56}Fe ratios of the grains imply elemental fractionation in the Si/S zone, or introduction of isotopically solar Fe by secondary processing. The two highly {sup 17}O-rich silicates exhibited significant {sup 25}Mg and/or {sup 26}Mg enrichments and their isotopic ratios are best explained by strong dilution of 1.15 M {sub ☉} CO nova matter. We estimate that ∼12% and 1% of presolar silicates have SN and nova origins, respectively, similar to presolar SiC and oxides. This implies that asymptotic giant branch stars are the dominant dust producers in the galaxy.

  6. Studies on Separation Process and Production Technology of Boron Isotope

    Directory of Open Access Journals (Sweden)

    LI Jian-ping

    2014-02-01

    Full Text Available The boron isotopes separation test was performed by chemical exchange reaction in the benzene ether -three boron fluoride system, which resulted to the boron isotopic enrichment of -10 in the liquid phase, the boron isotopic enrichment of -11 in the gas phase. After then, boron isotope separation trial production has been finished. In this process, the exchange column and complex tower normal operating parameters and the complex tower technology have been obtained, the problems of material distillation purification is solved, boron isotopes feasibility with PTFE packing enrichment is verified in an exchange column. Also, effect of operating pressure, flow and other parameters on boron -10 isotopic enrichment experiments and the effect and properties of the PTFE packing have been investigated in the existing system. All the results are very useful for the industrialization of the boron isotopes separation system.

  7. THE ATOMIC WEIGHTS COMMISSION AND ISOTOPIC ABUNDANCE RATIO DETERMINATIONS.

    Energy Technology Data Exchange (ETDEWEB)

    HOLDEN, N.E.

    2005-08-07

    Following Thomson's discovery of stable isotopes in non-radioactive chemical elements, the derivation of atomic weight values from mass spectrometric measurements of isotopic abundance ratios moved very slowly. Forty years later, only 3 1/2 % of the recommended values were based on mass spectrometric measurements and only 38% in the first half century. It might be noted that two chemical elements (tellurium and mercury) are still based on chemical measurements, where the atomic weight value calculated from the relative isotopic abundance measurement either agrees with the value from the chemical measurement or the atomic weight value calculated from the relative isotopic abundance measurement falls within the uncertainty of the chemical measurement of the atomic weight. Of the 19 chemical elements, whose atomic weight is based on non-corrected relative isotopic abundance measurements, five of these are two isotope systems (indium, iridium, lanthanum, lutetium and tantalum) and one is a three-isotope system (oxygen).

  8. Production Situation and Technology Prospect of Medical Isotopes

    Directory of Open Access Journals (Sweden)

    GAO Feng;LIN Li;LIU Yu-hao;MA Xing-jun

    2016-10-01

    Full Text Available The isotope production technology was overviewed, including traditional and newest technology. The current situation of medical isotope production was introduced. The problems faced by isotope supply and demand were analyzed. The future development trend of medical isotopes and technology prospect were put forward. As the most populous country, nuclear medicine develops rapidly, however, domestic isotope mainly relies on imports. The highly productive and relatively safe MIPR is expected to be an effective way to breakthrough the bottleneck of the development of nuclear medicine. Traditional isotope production technologies with reactor can be improved. It's urgent to research and promote new isotope production technologies with reactor. Those technologies which do not depend on reactor will have a bright market prospects.

  9. Validation of adsorbents for sample preconcentration in compound-specific isotope analysis of common vapor intrusion pollutants.

    Science.gov (United States)

    Klisch, Monika; Kuder, Tomasz; Philp, R Paul; McHugh, Thomas E

    2012-12-28

    Isotope ratios of volatile organic compounds (VOCs) in the environment are often of interest in contaminant fate studies. Adsorbent preconcentration-thermal desorption of VOCs can be used to collect environmental vapor samples for compound-specific isotope analysis (CSIA). While active adsorbent samplers offer logistic benefits in handling large volumes of air, their performance in preserving VOCs isotope ratios was not previously tested under sampling conditions corresponding to typical indoor air sampling conditions. In this study, the performance of selected adsorbents was tested for preconcentration of TCE (for determination of C and Cl isotope ratios), PCE (C and Cl) and benzene (C and H). The key objective of the study was to identify the adsorbent(s) permitting preconcentration of the target VOCs present in air at low μg/m(3) concentrations, without significant alteration of their isotope ratios. Carboxen 1016 was found to perform well for the full range of tested parameters. Carboxen 1016 can be recommended for sampling of TCE, PCE and benzene, for CSIA, from air volumes up to 100 L. Variable extent of isotope ratio alteration was observed in the preconcentration of the target VOCs on Carbopack B and Carbopack X, resulting from partial analyte loss via adsorbent bed breakthrough and (possibly) via incomplete desorption. The results from testing the Carbopack B and Carbopack X highlight the need of adsorbent performance validation at conditions fully representative of actual sample collection conditions, and caution against extrapolation of performance data toward more challenging sampling conditions.

  10. Late Permian-earliest Triassic high-resolution organic carbon isotope and palynofacies records from Kap Stosch (East Greenland)

    Science.gov (United States)

    Sanson-Barrera, Anna; Hochuli, Peter A.; Bucher, Hugo; Schneebeli-Hermann, Elke; Weissert, Helmut; Adatte, Thierry; Bernasconi, Stefano M.

    2015-10-01

    During and after the end Permian mass extinction terrestrial and marine biota underwent major changes and reorganizations. The latest Permian and earliest Triassic is also characterized by major negative carbon isotope shifts reflecting fundamental changes in the carbon cycle. The present study documents a high-resolution bulk organic carbon isotope record and palynofacies analysis spanning the latest Permian-earliest Triassic of East Greenland. An almost 700 meter thick composite section from Kap Stosch allowed discriminating 6 chemostratigraphic intervals that provide the basis for the correlation with other coeval records across the world, and for the recognition of basin wide transgressive-regressive events documenting tectonic activity during the opening of the Greenland-Norway Basin. The identification of the main factors that influenced the organic carbon isotope signal during the earliest Triassic (Griesbachian to Dienerian) was possible due to the combination of bulk organic carbon isotope, palynofacies and Rock-Eval data. Two negative carbon isotopic shifts in the Kap Stosch record can be correlated with negative shifts recorded in coeval sections across the globe. A first negative shift precedes the base of the Triassic as defined by the first occurrence of the conodont Hindeodus parvus in the Meishan reference section, and the second one coincides with the suggested Griesbachian-Dienerian boundary. This new organic carbon isotope record from the extended Kap Stosch section from the Boreal Realm documents regional and global carbon cycle signals of the interval between the latest Palaeozoic and the onset of the Mesozoic.

  11. Analysis of high burnup pressurized water reactor fuel using uranium, plutonium, neodymium, and cesium isotope correlations with burnup

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Suk; Jeon, Young Shin; Park, Soon Dal; Ha, Yeong Keong; Song, Kyu Seok [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-12-15

    The correlation of the isotopic composition of uranium, plutonium, neodymium, and cesium with the burnup for high burnup pressurized water reactor fuels irradiated in nuclear power reactors has been experimentally investigated. The total burnup was determined by Nd-148 and the fractional {sup 235}U burnup was determined by U and Pu mass spectrometric methods. The isotopic compositions of U, Pu, Nd, and Cs after their separation from the irradiated fuel samples were measured using thermal ionization mass spectrometry. The contents of these elements in the irradiated fuel were determined through an isotope dilution mass spectrometric method using {sup 233}U, {sup 242}Pu, {sup 150}Nd, and {sup 133}Cs as spikes. The activity ratios of Cs isotopes in the fuel samples were determined using gamma-ray spectrometry. The content of each element and its isotopic compositions in the irradiated fuel were expressed by their correlation with the total and fractional burnup, burnup parameters, and the isotopic compositions of different elements. The results obtained from the experimental methods were compared with those calculated using the ORIGEN-S code.

  12. A new class of medicament: radioactivity isotopes (1962); Une nouvelle classe de medicaments: les isotopes radioactifs (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    Very many radioelement are used in medicine, either for diagnosis or as therapeutics. The development of medicine has entailed an increase in the number of application of radioactive isotopes. Firstly used in the form of simple inorganic molecules for diagnosis or as anticancer therapeutics, radioelements are now used for labelling organic molecules, allowing functional specific studies of any kind of nature. Their production is made difficult by their radio-active properties. Their pharmaceutical properties, determined by tests and controls, depend either from radiochemistry and from medicine. The author reminds, in this report, the methods for the preparation and analysis, and set out the medical application. (author) [French] De tres nombreux radioelements trouvent une application en medecine humaine, soit dans le diagnostic, soit en therapeutique. L'evolution de la medecine entraine un accroissement du champ d'application des isotopes radioactifs. D'abord utilises sous forme de molecules minerales simples, pour les diagnostics ou des therapeutiques anticancereuses, les radioelements sont maintenant introduits dans des molecules organiques qui permettent des etudes fonctionnelles specifiques de toute nature. Leur fabrication est compliquee par leurs proprietes radioactives. Leurs caracteristiques pharmaceutiques determinees par des essais et controles, sont liees d'une part a la radiochimie, d'autre part a la medecine. L'auteur rappelle, dans cet expose, les methodes de preparation et d'analyse et aborde les applications medicales. (auteur)

  13. Oxygen isotope composition of mafic magmas at Vesuvius

    Science.gov (United States)

    Dallai, L.; Cioni, R.; Boschi, C.; D'Oriano, C.

    2009-12-01

    The oxygen isotope composition of olivine and clinopyroxene from four plinian (AD 79 Pompeii, 3960 BP Avellino), subplinian (AD 472 Pollena) and violent strombolian (Middle Age activity) eruptions were measured to constrain the nature and evolution of the primary magmas of the last 4000 years of Mt. Vesuvius activity. A large set of mm-sized crystals was accurately separated from selected juvenile material of the four eruptions. Crystals were analyzed for their major and trace element compositions (EPMA, Laser Ablation ICP-MS), and for 18O/16O ratios. As oxygen isotope composition of uncontaminated mantle rocks on world-wide scale is well constrained (δ18Oolivine = 5.2 ± 0.3; δ18Ocpx = 5.6 ± 0.3 ‰), the measured values can be conveniently used to monitor the effects of assimilation/contamination of crustal rocks in the evolution of the primary magmas. Instead, typically uncontaminated mantle values are hardly recovered in Italian Quaternary magmas, mostly due to the widespread occurrence of crustal contamination of the primary magmas during their ascent to the surface (e.g. Alban Hills, Ernici Mts., and Aeolian Islands). Low δ18O values have been measured in olivine from Pompeii eruption (δ18Oolivine = 5.54 ± 0.03‰), whereas higher O-compositions are recorded in mafic minerals from pumices or scoria of the other three eruptions. Measured olivine and clinopyroxene share quite homogeneous chemical compositions (Olivine Fo 85-90 ; Diopside En 45-48, respectively), and represent phases crystallized in near primary mafic magmas, as also constrained by their trace element compositions. Data on melt inclusions hosted in crystals of these compositions have been largely collected in the past demonstrating that they crystallized from mafic melt, basaltic to tephritic in composition. Published data on volatile content of these melt inclusions reveal the coexistence of dissolved water and carbon dioxide, and a minimum trapping pressure around 200-300 MPa, suggesting

  14. The significance of an Early Jurassic (Toarcian) carbon-isotope excursion in Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada

    Science.gov (United States)

    Caruthers, Andrew H.; Gröcke, Darren R.; Smith, Paul L.

    2011-07-01

    During the Early Toarcian there was a significant disruption in the short-term active carbon reservoir as revealed by carbon-isotope records, which show a broad positive shift that is interrupted by a large 5-7‰ negative excursion (δ 13C org). Carbon-isotope excursion co-occurs with the deposition of organic-rich shales in many areas. This perturbation in carbon isotopes is thought to be indicative of severe climate change and marine anoxia. The two leading hypotheses as to the cause of this event invoke either global or regional controls. Here we present carbon-isotope data from Haida Gwaii, British Columbia, Canada showing a significant perturbation within a temporally constrained Early Toarcian succession that was deposited in the northeastern paleo-Pacific Ocean. These data reinforce the concept that the short-term active carbon reservoir was affected globally, and assist with the correlation of ammonite zonal schemes between western North America and Europe. The δ 13C org data show a broad positive shift that is interrupted by a sharp and pronounced negative excursion of 7‰ (8.5‰ in δ 13C wood) in the Early Toarcian Kanense Zone. This negative excursion also coincides with increasing total organic carbon (TOC) from ~ 0.4% to ~ 1.2%. These data suggest that the Early Toarcian carbon-isotope perturbation was indeed global and imprinted itself on all active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric).

  15. Carbon isotopes as indicators of peatland growth?

    Science.gov (United States)

    Alewell, Christine; Krüger, Jan Paul; von Sengbusch, Pascal; Szidat, Sönke; Leifeld, Jens

    2016-04-01

    As undisturbed and/or growing peatlands store considerable amounts of carbon and are unique in their biodiversity and species assemblage, the knowledge of the current status of peatlands (growing with carbon sequestration, stagnating or degrading with carbon emissions) is crucial for landscape management and nature conservation. However, monitoring of peatland status requires long term measurements and is only feasible with expert knowledge. The latter determination is increasingly impeded in a scientific world, where taxonomic expert knowledge and funding of long term monitoring is rare. Stable carbon and nitrogen isotopes depth profiles in peatland soils have been shown to be a useful tool to monitor the degradation of peatlands due to permafrost thawing in Northern Sweden (Alewell et al., 2011; Krüger et al., 2014), drainage in Southern Finland (Krüger et al., 2016) as well as land use intensification in Northern Germany (Krüger et al., 2015). Here, we tackle the questions if we are able to differentiate between growing and degrading peats with the use of a combination of carbon stable (δ13C) and radiogenic isotope data (14C) with peat stratification information (degree of humification and macroscopic plant remains). Results indicate that isotope data are a useful tool to approximate peatland status, but that expert taxonomic knowledge will be needed for the final conclusion on peatland growth. Thus, isotope tools might be used for landscape screening to pin point sites for detailed taxonomic monitoring. As the method remains qualitative future research at these sites will need to integrate quantitative approaches to determine carbon loss or gain (soil C balances by ash content or C accumulation methods by radiocarbon data; Krüger et al., 2016). Alewell, C., R. Giesler, J. Klaminder, J. Leifeld, and M. Rollog. 2011. Stable carbon isotopes as indicators for micro-geomorphic changes in palsa peats. Biogeosciences, 8, 1769-1778. Krüger, J. P., Leifeld, J

  16. N Isotopes in Nile Sediments (ethiopia, Sudan)

    Science.gov (United States)

    Padoan, M.; Villa, I. M.; Garzanti, E.; Galbusera, M.; Quistini, S.; Peruta, L.; El Kammar, A.

    2009-04-01

    The Nile is the most important river of the Eastern Mediterranean. Its water and sediment fluxes have greatly influenced marine circulation throughout the Quaternary, and are widely considered as possible causes for stagnation and formation of sapropel (Krom et al., 1999a; 2002; Talbot et al., 2000; Freydier et al., 2001; Weldeab et al., 2002; Scrivner et al., 2004). Variations in annual flooding and baseflow of the river Nile, controlled by climate changes, had major impact on the rise and demise of Egyptian dynasties (Stanley et al., 2003). In order to better define sedimentary sources of the Nile system and to obtain more robust results, we have analyzed Nd isotopes in sediments of all its major Sudanese and Ethiopian tributaries (Atbara, Gash, Abay, Didesa, Dabus, White Nile, Bahr Ez Zeraf) in several replicate samples. Analyses were carried out on distinct mud and sand fractions (STANLEY, J.D., CLIFF, R.A., WOODWARD, J.C., 2002. Nile River sediment fluctuations over the past 7000 yr and their key role in sapropel development. Geol., 30, n. 1, 71-74. PADOAN M., GALBUSERA M., QUISTINI S., VILLA I.M., AND GARZANTI E., 2007 Isotopic tracers of Nile sediment sources. AGU Fall Meeting, San Francisco December 2007. PIK, R., DENIEL, C., COULON, C., YIRGU, G., MARTY, B., 1999, Isotopic and trace element signatures of Ethiopian flood basalts: Evidence for plume-lithosphere interactions. Geochim. Cosmochim. Acta, 63, 2263-2279. SCRIVNER, A., VANCE, D., ROHLING, E.J., 2004. New neodymium isotope data quantify Nile involvement in Mediterranean anoxic episodes. Geol., 32, n. 7, 565-568. STANLEY, J.D., KROM, M.D., CLIFF, R.A., WOODWARD, J.C., 2003. Short Contribution: Nile flow failure at the End of the Old Kingdom, Egypt: strontium isotopic and petrologic evidence. TALBOT, M.R., WILLIAMS, M.A.J., ADAMSON, D.A., 2000. Strontium isotope evidence for late Pleistocene reestablishment of an integrated Nile drainage network. Geol., 28, n. 4, 343-346. WELDEAB, S., EMEIS, K

  17. Distribution of uranium isotopes in surface water of the Llobregat river basin (Northeast Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, A.; Devesa, R.; Valles, I.; Serrano, I.; Soler, J.; Blazquez, S.; Ortega, X.; Matia, L. [University of Politecn Cataluna, Barcelona (Spain)

    2010-12-15

    A study is presented on the distribution of U-234, U-238, U-235 isotopes in surface water of the Llobregat river basin (Northeast Spain), from 2001 to 2006. Sixty-six superficial water samples were collected at 16 points distributed throughout the Llobregat river basin. Uranium isotopes were measured by alpha spectrometry (PIPS detectors). The test procedure was validated according to the quality requirements of the ISO17025 standard. The activity concentration for the total dissolved uranium ranges from 20 to 261 mBq L{sup -1}. The highest concentrations of uranium were detected in an area with formations of sedimentary rock, limestone and lignite. A high degree of radioactive disequilibrium was noted among the uranium isotopes. The U-234/R-238 U activity ratio varied between 1.1 and 1.9 and the waters with the lowest uranium activity registered the highest level of U-234/U-238 activity ratio. Correlations between uranium activity in the tested water and chemical and physical characteristics of the aquifer were found.

  18. Clumped-isotope geochemistry of carbonates: A new tool for the reconstruction of temperature and oxygen isotope composition of seawater

    Energy Technology Data Exchange (ETDEWEB)

    Bernasconi, Stefano M., E-mail: Stefano.bernasconi@erdw.ethz.ch [Geological Institute, ETH Zuerich, Sonneggstrasse 5, 8092 Zuerich (Switzerland); Schmid, Thomas W.; Grauel, Anna-Lena [Geological Institute, ETH Zuerich, Sonneggstrasse 5, 8092 Zuerich (Switzerland); Mutterlose, Joerg [Institut fuer Geologie, Mineralogie und Geophysik, Ruhr Universitaet Bochum, Universitaetsstr. 150, 44801 Bochum (Germany)

    2011-06-15

    Highlights: > Clumped-isotope thermometry of carbonates is discussed. > Clumped isotopes of Belemnites show higher sea surface temperatures than commonly assumed for the lower Cretaceous. > The potential of clumped-isotope measurement on foraminifera is discussed. - Abstract: Clumped-isotope geochemistry deals with State of ordering of rare isotopes in molecules, in particular with their tendency to form bonds with other rare isotopes rather than with the most abundant ones. Among its possible applications, carbonate clumped-isotope thermometry is the one that has gained most attention because of the wide potential of applications in many disciplines of the earth sciences. In particular, it allows reconstructing the temperature of formation of carbonate minerals without knowledge of the isotopic composition of the water from which they were formed. In addition, the O isotope composition of the waters from which they were formed can be calculated using the {delta}{sup 18}O of the same carbonate sample. This feature offers new approaches in paleoclimatology for reconstructing past global geochemical cycles. In this contribution two applications of this method are presented. First the potential of a new analytical method of measurement of clumped isotopes on small samples of foraminifera, for high-resolution SST and seawater {delta}{sup 18}O reconstructions from marine sediments is shown. Furthermore the potential of clumped isotope analysis of belemnites, for reconstructing seawater {delta}{sup 18}O and temperatures in the Cretaceous is shown.

  19. Forensic utility of the carbon isotope ratio of PVC tape backings

    Science.gov (United States)

    Stern, L. A.; Thompson, A. H.; Mehltretter, A. H.; McLaskey, V.; Parish, A.; Aranda, R.

    2008-12-01

    Forensic interest in adhesive tapes with PVC-backings (polyvinyl chloride, electrical tapes) derives from their use in construction of improvised explosive devices, drug packaging and in a variety of other illicit activities. Due to the range of physical characteristics and chemical compositions of such tapes, traditional microscopic and chemical analysis of the tape backings and adhesives offer a high degree of discrimination between tapes from different manufacturers and products. To evaluate whether carbon isotope ratios may be able to increase discrimination of electrical tapes, particularly with regards to different tapes of the same product, we assessed the PVC-backings of 87 rolls of black electrical tape for their δ13C values. The adhesive on these tapes was physically removed with hexane, and plasticizers within the PVC tape backings were removed by three-20 minute extractions with chloroform. The δ13C values of the PVC tape backings ranged between -23.8 and -41.5 (‰ V-PDB). The carbon isotopic variation within a product (identical brand and product identification) is significant, based on five products with at least 3 rolls (ranges of 7.4‰ (n=3), 10.0‰ (n=6), 4.2‰ (n=16), 3.8‰ (n=6), and 11.5‰ (n=8), respectively). There was no measurable carbon isotope variation in regards to the following: a) along the length of a roll (4 samples from 1 roll); b) between the center and edge of a strip of tape (1 pair); c) between rolls assumed to be from the same lot of tape (2 pairs); d) between different rolls from the same batch of tape (same product purchased at the same time and place; 5 pairs); and e) between samples of a tape at room temperature, heated to 50° C and 80° C for 1 week. For each sample within the population of 87 tapes, carbon isotopes alone exclude 80 to 100% of the tapes as a potential match, with an average exclusion power of 92.5%, using a window of ± 0.4‰. Carbon isotope variations originate from variations in starting

  20. ISOTOPIC REGIME OF SUBGLACIAL LAKE VOSTOK ON EVIDENCE FROM DEEP ICE CORE STUDIES

    Directory of Open Access Journals (Sweden)

    A. A. Ekaykin

    2012-01-01

    Full Text Available On the 5th of February 2012 the long-lasting project of deep ice drilling at Russian Antarctic station of Vostok was completed by the penetration to the subglacial lake at the depth of 3769.3 m. The study of the ice core representing the frozen lake water and obtained as a result of the drilling, has allowed to make preliminary conclusions on the lake hydrological regime before its direct studies. In this work we present the new isotopic data (dD and d18O from the 5G-2 ice core from the depth interval 3600–3720 m. The measurements were performed in the recently established Climate and Environment Research Laboratory of Arctic and Antarctic Research Institute (St. Petersburg,Russia. The comparison of the new isotope profile with the previously published 5G-1 data (3540–3650 m demonstrates a good reproducibility, which means a satisfying quality of the measurements. The analysis of the whole available lake ice thickness isotope profile (3540–3720 m has allowed to obtain a new information on theLakeVostok’s hydrological regime. Based on the isotopic behavior, the lake ice core is divided into three sections. The first (3540–3619 m corresponds to the so-called «lake ice 1», the ice containing visible mineral inclusions that was formed close to the western lake shore. The isotopic variability in this section was formed due to the changing conditions and mechanisms of the ice formation (ice accretion rate, concentrations of the frazil ice crystals and frozen water pockets. The second (3619–3647 m is characterized by a weak correlation between deuterium and oxygen 18, which is interpreted as an influence of the hydrothermal activity on the lake’s isotopic regime. In the third section (3647–3720 m, formed over the deep basin in the southern part of the lake, the isotopic variability is reduced due to the relatively stable steady-state conditions of the ice formation. At the same time, the signature of the lake water isotopic

  1. Tracing industrial heavy metal inputs to topsoils using using cadmium isotopes

    Science.gov (United States)

    Huang, Y.; Ma, L.; Ni, S.; Lu, H.; Liu, Z.; Zhang, C.; Guo, J.; Wang, N.

    2015-12-01

    Anthropogenic activities have dominated heavy metal (such as Cd, Pb, and Zn) cycling in many environments. The extent and fate of these metal depositions in topsoils, however, have not been adequately evaluated. Here, we utilize an innovative Cadmium (Cd) isotope tool to trace the sources of metal pollutants in topsoils collected from surrounding a Vanadium Titanium Magnetite smelting plant in Sichuan, China. Topsoil samples and possible pollution end-members such as fly ashes, bottom ashes, ore materials, and coal were also collected from the region surrounding the smelting plant and were analyzed for Cd isotope ratios (d114Cd relative to Cd NIST 3108). Large Cd isotope fractionation (up to 3 ‰) was observed in these industrial end-members: fly ashes possessed higher δ114Cd values ranging from +0.03 to +0.19‰; bottom fly ashes have lower δ114Cd values ranging from -0.35 to -2.46‰; and unprocessed ore and coal samples has δ114Cd value of -0.40‰. This fractionation can be attributed to the smelting processes during which bottom ashes acquired lighter Cd isotope signatures while fly ashes were mainly characterized by heavy isotope ratios, in comparison to the unprocessed ore and coal samples. Indeed, δ114Cd values of topsoils in the smelting area range from 0.29 to -0.56‰, and more than half of the soils analyzed have distinct δ114Cd values > 0‰. Cd isotopes and concentrations measured in topsoils suggested that processed materials (fly and bottom ashes from ore and coal actually used by the smelting plant) were the major source of Cd in soils. In a δ114Cd vs 1/Cd mixing diagram, the soils represent a mixture of three identified end members (fly ash, bottom ash and deep unaffected soil) with distinct Cd isotopic compositions and concentrations. Deep soils have the same δ114Cd values range as the unprocessed ore and coal, which indicated the Cd isotope fractionation did occur during evaporation and condensation processes inside the smelting plant

  2. Quinone-based stable isotope probing for assessment of 13C substrate-utilizing bacteria

    Science.gov (United States)

    Kunihiro, Tadao; Katayama, Arata; Demachi, Toyoko; Veuger, Bart; Boschker, Henricus T. S.; van Oevelen, Dick

    2015-04-01

    In this study, we attempted to establish quinone-stable-isotope probing (SIP) technique to link substrate-utilizing bacterial group to chemotaxonomic group in bacterial community. To identify metabolically active bacterial group in various environments, SIP techniques combined with biomarkers have been widely utilized as an attractive method for environmental study. Quantitative approaches of the SIP technique have unique advantage to assess substrate-incorporation into bacteria. As a most major quantitative approach, SIP technique based on phospholipid-derived fatty acids (PLFA) have been applied to simultaneously assess substrate-incorporation rate into bacteria and microbial community structure. This approach is powerful to estimate the incorporation rate because of the high sensitivity due to the detection by a gas chromatograph-combustion interface-isotope ratio mass spectrometer (GC-c-IRMS). However, its phylogenetic resolution is limited by specificity of a compound-specific marker. We focused on respiratory quinone as a biomarker. Our previous study found a good correlation between concentrations of bacteria-specific PLFAs and quinones over several orders of magnitude in various marine sediments, and the quinone method has a higher resolution (bacterial phylum level) for resolving differences in bacterial community composition more than that of bacterial PLFA. Therefore, respiratory quinones are potentially good biomarkers for quantitative approaches of the SIP technique. The LC-APCI-MS method as molecular-mass based detection method for quinone was developed and provides useful structural information for identifying quinone molecular species in environmental samples. LC-MS/MS on hybrid triple quadrupole/linear ion trap, which enables to simultaneously identify and quantify compounds in a single analysis, can detect high molecular compounds with their isotope ions. Use of LC-MS/MS allows us to develop quinone-SIP based on molecular mass differences due to

  3. A new approach to quantifying internal diffusion resistances and CO2 isotope exchange in leaves

    Science.gov (United States)

    West, Jason; Ogée, Jérôme; Burlett, Régis; Gimeno, Teresa; Genty, Bernard; Jones, Samuel; Wohl, Steven; Bosc, Alexandre; Wingate, Lisa

    2016-04-01

    The oxygen isotopic composition (δ18O) of atmospheric CO2 can constrain the global CO2 budget at a range of scales, offering the potential to partition net CO2 exchanges into their component gross fluxes and provide insights to linkages between C and water cycles. However, there are significant limitations to utilizing the δ18O of CO2 to constrain C budgets because of uncertainties associated with the isotopic exchange of CO2 with terrestrial water pools. Leaf water in particular represents a critical pool with ongoing debates about its enrichment in heavy isotopes during transpiration and the hydration of CO2 and its oxygen isotope exchange with this pool. Isotopic heterogeneity of the leaf water, the spatial distribution and activity of carbonic anhydrase (CA) within leaves, and resistance to diffusion of CO2 from the substomatal cavity to chloroplasts are all key components with important uncertainties. Better constraints on these would significantly improve our ability to understand and model the global C budget as well as yield insights to fundamental aspects of leaf physiology. We report results using a new measurement system that permits the simultaneous measurement of the 13C and 18O composition of CO2 and the 18O isotopic composition of leaf transpiration. As this new approach permits rapid alteration of the isotopic composition of gases interacting with the leaf, key model parameters can be derived directly and simultaneously. Hence, our approach dos not rely on separate measurements shifted in time from the gas exchange measurements or that may not quantify the relevant scale of heterogeneity (e.g., CA enzyme assays or bulk leaf water extraction and analysis). In particular, this new method explicitly distinguishes the leaf mesophyll resistance to CO2 transport relevant for photosynthesis from the resistance required for interpreting the δ18O of CO2 and allows us to derive other relevant parameters directly. This new measurement system and modeling

  4. Ion implantation system and process for ultrasensitive determination of target isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, III, Orville T.; Liezers, Martin

    2016-09-13

    A system and process are disclosed for ultrasensitive determination of target isotopes of analytical interest in a sample. Target isotopes may be implanted in an implant area on a high-purity substrate to pre-concentrate the target isotopes free of contaminants. A known quantity of a tracer isotope may also be implanted. Target isotopes and tracer isotopes may be determined in a mass spectrometer. The present invention provides ultrasensitive determination of target isotopes in the sample.

  5. Radioactive isotopes in solid-state physics

    CERN Document Server

    Deicher, M

    2002-01-01

    Radioactive atoms have been used in solid-state physics and in material science for many decades. Besides their classical application as tracer for diffusion studies, nuclear techniques such as M\\"ossbauer spectroscopy, perturbed angular correlation, $\\beta$-NMR, and emission channelling have used nuclear properties (via hyperfine interactions or emitted particles) to gain microscopical information on the structural and dynamical properties of solids. During the last decade, the availability of many different radioactive isotopes as a clean ion beam at ISOL facilities such as ISOLDE at CERN has triggered a new era involving methods sensitive for the optical and electronic properties of solids, especially in the field of semiconductor physics. Extremely sensitive spectroscopic techniques like deep-level transient spectroscopy (DLTS), photoluminescence (PL), and Hall effect have gained a new quality by using radioactive isotopes. Because of their decay the chemical origin of an observed electronic and optical b...

  6. (n,{gamma}) Experiments on tin isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Rusev, G. [North Carolina State University, Raleigh, NC 27695, USA and Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O' Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Becvar, F.; Krticka, M.; Kroll, J. [Charles University of Prague, V Holesovickach 2, 180 00 Prague 8 (Czech Republic); Agvaanluvsan, U.; Dashdorj, D.; Erdenehuluun, B.; Tsend-Ayush, T. [MonAme Scientific Research Center, Ulaanbaatar (Mongolia)

    2013-04-19

    Neutron capture experiments on highly enriched {sup 117,119}Sn isotopes were performed with the DANCE detector array located at the Los Alamos Neutron Science Center. The DANCE detector provides detailed information about the multi-step {gamma}-ray cascade following neutron capture. Analysis of the experimental data provides important information to improve understanding of the neutron capture reaction, including a test of the statistical model, the assignment of spins and parities of neutron resonances, and information concerning the Photon Strength Function (PSF) and Level Density (LD) below the neutron separation energy. Preliminary results for the (n,{gamma}) reaction on {sup 117,119}Sn are presented. Resonance spins of the odd-A tin isotopes were almost completely unknown. Resonance spins and parities have been assigned via analysis of the multi-step {gamma}-ray spectra and directional correlations.

  7. New isotopes of interest to astrophysics

    CERN Document Server

    Davids, C N; Pardo, R C; Parks, L A

    1976-01-01

    The beta decays of the new isotopes /sup 53/Ti and /sup 59/Mn have been studied. These neutron-rich isotopes have half-lives of 32.7+or-0.9 s and 4.75+or-0.14 s, respectively. They were produced via the /sup 48/Ca(/sup 7/Li, pn)/sup 53/Ti and /sup 48/Ca(/sup 13/C, pn) /sup 59/Mn reactions using beams from the Argonne National Laboratory FN Tandem Van de Graaff accelerator. Measurement of gamma singles, gamma - gamma coincidences, and beta - gamma coincidences were facilitated by a pneumatic target-transfer system ('rabbit'). Decay schemes are presented, and the measured masses compared with various predictions. The relevance to astrophysics will be discussed. In addition, a new 8-target multiple rabbit system will be described. (7 refs).

  8. Atom Trap Trace Analysis of Ca Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, S., E-mail: hoekstra@fhi-berlin.mgp.de [Fritz-Haber Institut der Max-Planck Gesellschaft (Germany); Mollema, A. K.; Morgenstern, R.; Willmann, L.; Wilschut, H. W.; Hoekstra, R. [Rijksuniversiteit Groningen, Atomic Physics, KVI (Netherlands)

    2005-04-15

    In our experiment we aim at the detection of the rarest, naturally occuring calcium isotope 41Ca by means of atom trap trace analysis. On basis of single-atom detection of 46Ca our present sensitivity for 41Ca is estimated to be 1 atom per hour at an abundance of 10-12. To reach a sensitivity at the level of natural abundance, which is 10-14, we need to reduce atomic beam losses. To achieve this, optical compression of the atomic beam is a promising option. We use Monte Carlo Simulations to demonstrate that optical compression of the atomic beam increases throughput of the atomic beam as well as isotope selectivity.

  9. Helium and carbon isotopes in Indian diamonds

    Science.gov (United States)

    Wiens, R.; Lal, D.; Craig, H.

    1990-09-01

    Helium and carbon isotope measurements in Indian diamonds (from Andhra Pradesh) were carried out using samples that included mined diamonds from primary kimberlite source rocks and alluvial diamonds from river gravel. The He and C isotope concentrations in diamonds from these two sources were compared, and the Indian diamonds were compared to those from other regions. Results indicate that most of the He-3 in the alluvial diamonds is of cosmogenic origin and that the alluvial diamonds may also have a significant He-4 component due to alpha particles implanted during storage in a secondary matrix. One diamond, a mined kimberlite specimen, was found to have the lowest He-4 content (0.018 microcc/g) so far recorded in diamonds.

  10. Multi-neutron emission of Cd isotopes

    CERN Document Server

    Severyukhin, A P; Borzov, I N; Sushenok, E O

    2016-01-01

    An influence of the phonon-phonon coupling (PPC) on the $\\beta$-decay half-lives and multi-neutron emission probabilities is analysed within the microscopic model based on the Skyrme interaction with tensor components included. The finite-rank separable approximation is used in order to handle large two-quasiparticle spaces. The even-even nuclei near the r-process pathes at $N=82$ are studied. The characteristics of ground states, $2^+$ excitations and $\\beta$-decay strength of the neutron-rich Cd isotopes are treated in detail. It is shown that a strong redistribution of the Gamow-Teller strength due to the PPC is mostly sensitive to the multi-neutron emission probability of the Cd isotopes.

  11. Finite mixture models for the computation of isotope ratios in mixed isotopic samples

    Science.gov (United States)

    Koffler, Daniel; Laaha, Gregor; Leisch, Friedrich; Kappel, Stefanie; Prohaska, Thomas

    2013-04-01

    Finite mixture models have been used for more than 100 years, but have seen a real boost in popularity over the last two decades due to the tremendous increase in available computing power. The areas of application of mixture models range from biology and medicine to physics, economics and marketing. These models can be applied to data where observations originate from various groups and where group affiliations are not known, as is the case for multiple isotope ratios present in mixed isotopic samples. Recently, the potential of finite mixture models for the computation of 235U/238U isotope ratios from transient signals measured in individual (sub-)µm-sized particles by laser ablation - multi-collector - inductively coupled plasma mass spectrometry (LA-MC-ICPMS) was demonstrated by Kappel et al. [1]. The particles, which were deposited on the same substrate, were certified with respect to their isotopic compositions. Here, we focus on the statistical model and its application to isotope data in ecogeochemistry. Commonly applied evaluation approaches for mixed isotopic samples are time-consuming and are dependent on the judgement of the analyst. Thus, isotopic compositions may be overlooked due to the presence of more dominant constituents. Evaluation using finite mixture models can be accomplished unsupervised and automatically. The models try to fit several linear models (regression lines) to subgroups of data taking the respective slope as estimation for the isotope ratio. The finite mixture models are parameterised by: • The number of different ratios. • Number of points belonging to each ratio-group. • The ratios (i.e. slopes) of each group. Fitting of the parameters is done by maximising the log-likelihood function using an iterative expectation-maximisation (EM) algorithm. In each iteration step, groups of size smaller than a control parameter are dropped; thereby the number of different ratios is determined. The analyst only influences some control

  12. Unbiased isotope equilibrium factors from partial isotope exchange experiments in 3-exchange site systems

    Science.gov (United States)

    Agrinier, Pierre; Javoy, Marc

    2016-09-01

    Two methods are available in order to evaluate the equilibrium isotope fractionation factors between exchange sites or phases from partial isotope exchange experiments. The first one developed by Northrop and Clayton (1966) is designed for isotope exchanges between two exchange sites (hereafter, the N&C method), the second one from Zheng et al. (1994) is a refinement of the first one to account for a third isotope exchanging site (hereafter, the Z method). In this paper, we use a simple model of isotope kinetic exchange for a 3-exchange site system (such as hydroxysilicates where oxygen occurs as OH and non-OH groups like in muscovite, chlorite, serpentine, or water or calcite) to explore the behavior of the N&C and Z methods. We show that these two methods lead to significant biases that cannot be detected with the usual graphical tests proposed by the authors. Our model shows that biases originate because isotopes are fractionated between all these exchanging sites. Actually, we point out that the variable mobility (or exchangeability) of isotopes in and between the exchange sites only controls the amplitude of the bias, but is not essential to the production of this bias as previously suggested. Setting a priori two of the three exchange sites at isotopic equilibrium remove the bias and thus is required for future partial exchange experiments to produce accurate and unbiased extrapolated equilibrium fractionation factors. Our modeling applied to published partial oxygen isotope exchange experiments for 3-exchange site systems (the muscovite-calcite (Chacko et al., 1996), the chlorite-water (Cole and Ripley, 1998) and the serpentine-water (Saccocia et al., 2009)) shows that the extrapolated equilibrium fractionation factors (reported as 1000 ln(α)) using either the N&C or the Z methods lead to bias that may reach several δ per mil in a few cases. These problematic cases, may be because experiments were conducted at low temperature and did not reach high

  13. Plutonium, (137)Cs and uranium isotopes in Mongolian surface soils.

    Science.gov (United States)

    Hirose, K; Kikawada, Y; Igarashi, Y; Fujiwara, H; Jugder, D; Matsumoto, Y; Oi, T; Nomura, M

    2017-01-01

    Plutonium ((238)Pu and (239,240)Pu), (137)Cs and plutonium activity ratios ((238)Pu/(239,240)Pu) as did uranium isotope ratio ((235)U/(238)U) were measured in surface soil samples collected in southeast Mongolia. The (239,240)Pu and (137)Cs concentrations in Mongolian surface soils (surface soils (0.013-0.06) coincided with that of global fallout. The (235)U/(238)U atom ratios in the surface soil show the natural one. There was a good correlation between the (239,240)Pu and (137)Cs concentrations in the surface soils. We introduce the migration depth to have better understanding of migration behaviors of anthropogenic radionuclides in surface soil. We found a difference of the migration behavior between (239,240)Pu and (137)Cs from (137)Cs/(239,240)Pu - (137)Cs plots for the Mongolian and Tsukuba surface soils; plutonium in surface soil is migrated easier than (137)Cs.

  14. Early African Diaspora in colonial Campeche, Mexico: strontium isotopic evidence.

    Science.gov (United States)

    Price, T Douglas; Tiesler, Vera; Burton, James H

    2006-08-01

    Construction activities around Campeche's central park led to the discovery of an early colonial church and an associated burial ground, in use from the mid-16th century AD to the late 17th century. Remains of some individuals revealed dental mutilations characteristic of West Africa. Analyses of strontium isotopes of dental enamel from these individuals yielded unusually high (87)Sr/(86)Sr ratios, inconsistent with an origin in Mesoamerica, but consistent with an origin in West Africa in terrain underlain by the West Africa Craton, perhaps near the port of Elmina, a principal source of slaves for the New World during the 16th century. These individuals likely represent some of the earliest representatives of the African Diaspora in the Americas.

  15. Selenide isotope generator for the Galileo Mission. Program final report

    Energy Technology Data Exchange (ETDEWEB)

    1979-06-01

    This final report for the Selenide Isotope Generator for the Galileo Mission (SIG/GM) documents the work performed by Teledyne Energy Systems (TES) under US Department of Energy (DOE) Contract No. DE-AC01-78ET33009 (formerly ET-78-C-01-2865) during the period April 10, 1978 to June 30, 1979. Because of technical difficulties with the thermoelectric converter being developed by the 3M Company under separate DOE contract, a Stop Work Order, dated January 29, 1979, was issued by DOE. The TES effort up to the receipt of the Stop Work Order as well as limited technical activities up to the contract conclusion on June 30, 1979 are reported.