WorldWideScience

Sample records for abundance isotopic

  1. Maximum abundant isotopes correlation

    The neutron excess of the most abundant isotopes of the element shows an overall linear dependence upon the neutron number for nuclei between neutron closed shells. This maximum abundant isotopes correlation supports the arguments for a common history of the elements during nucleosynthesis. (Auth.)

  2. THE ATOMIC WEIGHTS COMMISSION AND ISOTOPIC ABUNDANCE RATIO DETERMINATIONS.

    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).

  3. Isotopic abundance in atom trap trace analysis

    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.

  4. Europium Isotopic Abundances in Very Metal-poor Stars

    Sneden, C; Lawler, J E; Burles, S M; Beers, T C; Fuller, G M; Sneden, Christopher; Cowan, John J.; Lawler, James E.; Burles, Scott; Beers, Timothy C.; Fuller, George M.

    2002-01-01

    Europium isotopic abundance fractions are reported for the very metal-poor, neutron-capture-rich giant stars CS 22892-052, HD 115444, and BD +17 3248. The abundance fractions, derived from analysis of several strong Eu II lines appearing in high-resolution spectra of these stars, are in excellent agreement with each other and with their values in the Solar System: fraction(\\iso{Eu}{151}) ~= fraction(\\iso{Eu}{153}) ~= 0.5. Detailed abundance studies of very metal-poor stars have previously shown that the total elemental abundances of stable atoms with atomic numbers z >= 56 typically match very closely those of a scaled solar-system r-process abundance distribution. The present results for the first time extend this agreement to the isotopic level.

  5. Literature survey of isotopic abundance data for 1987-1989

    Holden, N.E. (Brookhaven National Lab., Upton, NY (USA))

    1989-08-09

    I have compiled all of the data on isotopic abundance measurements and their variation in nature for the time period since the last General Assembly. Most of the data deals with the variations in the abundances as given by per mil deviations from some standard. As such, they are not of major interest to the Atomic Weights Commission. However, there were some measurements which are of general interest in this list.

  6. Literature survey of isotopic abundance data for 1987-1989

    I have compiled all of the data on isotopic abundance measurements and their variation in nature for the time period since the last General Assembly. Most of the data deals with the variations in the abundances as given by per mil deviations from some standard. As such, they are not of major interest to the Atomic Weights Commission. However, there were some measurements which are of general interest in this list

  7. Carbon abundances and isotope ratios in 70 bright M giants

    Approximate carbon abundances and 12C/13C isotope ratios are obtained for 70 M giant stars from intermediate-resolution spectrophotometry of the CO bands near 2.3 μm. A low mean carbon abundance ([C/H]=-0.64±0.29) is obtained, suggesting that standard mixing is insufficient to explain atmospheric abundances in M giants. HR 8795 appears to be exceptionally carbon deficient, and is worthy of further study as a possible weak G-band star descendant. (author)

  8. Carbon abundances and isotope ratios in 70 bright M giants

    Lazaro, C. (Inst. de Astrofisica de Canarias, Tenerife (Spain)); Lynas-Gray, A.E. (University Coll., London (UK). Dept. of Physics and Astronomy); Clegg, R.E.S. (Royal Greenwich Observatory, Cambridge (UK)); Mountain, C.M.; Zadrozny, A. (Imperial Coll. of Science and Technology, London (UK))

    1991-03-01

    Approximate carbon abundances and {sup 12}C/{sup 13}C isotope ratios are obtained for 70 M giant stars from intermediate-resolution spectrophotometry of the CO bands near 2.3 {mu}m. A low mean carbon abundance ((C/H)=-0.64+-0.29) is obtained, suggesting that standard mixing is insufficient to explain atmospheric abundances in M giants. HR 8795 appears to be exceptionally carbon deficient, and is worthy of further study as a possible weak G-band star descendant. (author).

  9. The abundance and isotopic composition of water in eucrites

    Barrett, T. J.; Barnes, J. J.; TartèSe, R.; Anand, M.; Franchi, I. A.; Greenwood, R. C.; Charlier, B. L. A.; Grady, M. M.

    2016-06-01

    Volatile elements play a key role in the dynamics of planetary evolution. Extensive work has been carried out to determine the abundance, distribution, and source(s) of volatiles in planetary bodies such as the Earth, Moon, and Mars. A recent study showed that the water in apatite from eucrites has similar hydrogen isotopic compositions compared to water in terrestrial rocks and carbonaceous chondrites, suggesting that water accreted very early in the inner solar system given the ancient crystallization ages (~4.5 Ga) of eucrites. Here, the measurements of water (reported as equivalent H2O abundances) and the hydrogen isotopic composition (δD) of apatite from five basaltic eucrites and one cumulate eucrite are reported. Apatite H2O abundances range from ~30 to ~3500 ppm and are associated with a weighted average δD value of -34 ± 67‰. No systematic variations or correlations are observed in H2O abundance or δD value with eucrite geochemical trend or metamorphic grade. These results extend the range of previously published hydrogen isotope data for eucrites and confirm the striking homogeneity in the H-isotopic composition of water in eucrites, which is consistent with a common source for water in the inner solar system.

  10. The abundance and isotopic composition of water in eucrites

    Barrett, T. J.; Barnes, J. J.; TartèSe, R.; Anand, M.; Franchi, I. A.; Greenwood, R. C.; Charlier, B. L. A.; Grady, M. M.

    2016-05-01

    Volatile elements play a key role in the dynamics of planetary evolution. Extensive work has been carried out to determine the abundance, distribution, and source(s) of volatiles in planetary bodies such as the Earth, Moon, and Mars. A recent study showed that the water in apatite from eucrites has similar hydrogen isotopic compositions compared to water in terrestrial rocks and carbonaceous chondrites, suggesting that water accreted very early in the inner solar system given the ancient crystallization ages (~4.5 Ga) of eucrites. Here, the measurements of water (reported as equivalent H2O abundances) and the hydrogen isotopic composition (δD) of apatite from five basaltic eucrites and one cumulate eucrite are reported. Apatite H2O abundances range from ~30 to ~3500 ppm and are associated with a weighted average δD value of -34 ± 67‰. No systematic variations or correlations are observed in H2O abundance or δD value with eucrite geochemical trend or metamorphic grade. These results extend the range of previously published hydrogen isotope data for eucrites and confirm the striking homogeneity in the H-isotopic composition of water in eucrites, which is consistent with a common source for water in the inner solar system.

  11. MGA, Pu Isotope Abundance from Multichannel Analyzer Gamma Spectra

    1 - Description of program or function: The MGA (Multiple Group Analysis) program determines the relative abundances of plutonium and other actinide isotopes in different materials. The program analyzes spectra taken of such samples using a 4096-channel germanium (Ge) gamma-ray spectrometer. The code can be run in a one or two detector mode. The first spectrum which is required and must be taken at a gain of .075 keV/channel with a high resolution planar detector, contains the 0-300 keV energy region. The second spectrum, which is optional, must be taken at a gain of 0.25 keV/channel; it becomes important when analyzing high burnup samples (concentration of Pu(241) greater than one percent). Isotopic analysis precision of one percent or better can be obtained, and no calibrations are required. The system also measures the abundances of U(235,238), Np-237, and Am-241. A special calibration option is available to perform a one-time peak-shape characterization when first using a new detector system. 2 - Method of solution: The basic method for determining the relative abundance of the isotopes of plutonium is to measure the intensity of two or more peaks from gamma rays of similar energy, but arising from different isotopes. Since the gamma-ray emission probabilities and half-lives are known, the atom ratios can be calculated provided relative detection efficiencies for the peaks can be estimated

  12. Resonance ionization mass spectrometry for isotopic abundance measurements

    Miller, C. M.

    1986-01-01

    Resonance ionization mass spectrometry (RIMS) is a relatively new laser-based technique for the determination of isotopic abundances. The resonance ionization process depends upon the stepwise absorption of photons from the laser, promoting atoms of the element of interest through progressively higher electronic states until an ion is formed. Sensitivity arises from the efficiency of the resonant absorption process when coupled with the power available from commercial laser sources. Selectivity derives naturally from the distinct electronic structure of different elements. This isobaric discrimination has provided the major impetus for development of the technique. Resonance ionization mass spectrometry was used for analysis of the isotopic abundances of the rare earth lutetium. Isobaric interferences from ytterbium severely effect the ability to measure small amounts of the neutron-deficient Lu isotopes by conventional mass spectrometric techniques. Resonance ionization for lutetium is performed using a continuous-wave laser operating at 452 nm, through a sequential two-photon process, with one photon exciting the intermediate resonance and the second photon causing ionization. Ion yields for microgram-sized quantities of lutetium lie between 10(6) and 10(7) ions per second, at overall ionization efficiencies approaching 10(-4). Discrimination factors against ytterbium greater than 10(6) have been measured. Resonance ionization for technetium is also being explored, again in response to an isobaric interference, molybdenum. Because of the relatively high ionization potential for Tc, three-photon, two-color RIMS processes are being developed.

  13. Deuterium/hydrogen natural isotopic abundance in fruit juices

    Stable isotopic analyses of various elements such as carbon, hydrogen and oxygen are currently applied for the authentification of naturalness of fruit juices. Deuterium is particularly of interest because of the wide variation of its abundance. Due to evaporation-transpiration the deuterium content of the water in fruit juices is enriched compared to local ground water. In the case of our investigation on apple, another fractionation, originating in technological process, was observed. The concentrated juice water is enriched by 6o/oo as compared to natural fruit juice water. (authors)

  14. Analysis Method for Isotope Abundance of 13C-urea

    In order to better control the effective content of 13C in 13C-urea reagent, the technique and the conditions for converting 13C-urea sample into the sample gas used in gas isotopic mass spectrometry detection by means of nitrite oxidation method and high temperature burning method were investigated. The results showed that the 13CO2 gas obtained from nitrite oxidation method with 2 mg 13C-urea samples and that from high temperature burning method with 1 mg 13C-urea samples can satisfy the demand of the mass spectrometer detection. The sodium nitrite reagent dosage, the reaction temperature and the reaction time of the sample gas preparation, as well as the treatment effect of copper oxide reagent etc.were sought experimentally. The high abundance 13C-urea testing was completed, the calculation and expression of the detection data were also determined, and the standard deviation were less than ±0.07%. (authors)

  15. Quantitative and In-Depth Survey of the Isotopic Abundance Distribution Errors in Shotgun Proteomics.

    Chang, Cheng; Zhang, Jiyang; Xu, Changming; Zhao, Yan; Ma, Jie; Chen, Tao; He, Fuchu; Xie, Hongwei; Zhu, Yunping

    2016-07-01

    Accuracy is an important metric when mass spectrometry (MS) is used in large-scale quantitative proteomics research. For MS-based quantification by extracting ion chromatogram (XIC), both the mass and intensity dimensions must be accurate. Although much research has focused on mass accuracy in recent years, less attention has been paid to intensity errors. Here, we investigated signal intensity measurement errors systematically and quantitatively using the natural properties of isotopic distributions. First, we defined a normalized isotopic abundance error model and presented its merits and demerits. Second, a comprehensive survey of the isotopic abundance errors using data sets with increasing sample complexities and concentrations was performed. We examined parameters such as error distribution, relationships between signal intensities within one isotopic cluster, and correlations between different peak errors in isotopic profiles. Our data demonstrated that the high resolution MS platforms might also generate large isotopic intensity measurement errors (approximately 20%). Meanwhile, this error can be reduced to less than 5% using a novel correction algorithm, which is based on the theoretical isotopic abundance distribution. Finally, a nonlinear relationship was observed as the abundance error decreased in isotopic profiles with higher intensity. Our findings are expected to provide insight into isotopic abundance recalibration in quantitative proteomics. PMID:27266261

  16. Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

    Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.

    1994-01-01

    The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.

  17. Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry

    Meier, A.L.

    1982-01-01

    The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe the relationship of the absorption of 6Li and 7Li lamp radiation is proposed as a means of calculating isotopic composition that is independent of total lithium concentration.

  18. Ion Mobility Mass Spectrometry Direct Isotope Abundance Analysis

    The nuclear forensics community is currently engaged in the analysis of illicit nuclear or radioactive material for the purposes of non-proliferations and attribution. One technique commonly employed for gathering nuclear forensics information is isotope analysis. At present, the state-of-the-art methodology for obtaining isotopic distributions is thermal ionization mass spectrometry (TIMS). Although TIMS is highly accurate at determining isotope distributions, the technique requires an elementally pure sample to perform the measurement. The required radiochemical separations give rise to sample preparation times that can be in excess of one to two weeks. Clearly, the nuclear forensics community is in need of instrumentation and methods that can expedite their decision making process in the event of a radiological release or nuclear detonation. Accordingly, we are developing instrumentation that couples a high resolution IM drift cell to the front end of a MS. The IM cell provides a means of separating ions based upon their collision cross-section and mass-to-charge ratio (m/z). Two analytes with the same m/z, but with different collision cross-sections (shapes) would exit the cell at different times, essentially enabling the cell to function in a similar manner to a gas chromatography (GC) column. Thus, molecular and atomic isobaric interferences can be effectively removed from the ion beam. The mobility selected chemical species could then be introduced to a MS for high-resolution mass analysis to generate isotopic distributions of the target analytes. The outcome would be an IM/MS system capable of accurately measuring isotopic distributions while concurrently eliminating isobaric interferences and laboratory radiochemical sample preparation. The overall objective of this project is developing instrumentation and methods to produce near real-time isotope distributions with a modular mass spectrometric system that performs the required gas-phase chemistry and

  19. Ion Mobility Mass Spectrometry Direct Isotope Abundance Analysis

    Manuel J. Manard, Stephan Weeks, Kevin Kyle

    2010-05-27

    The nuclear forensics community is currently engaged in the analysis of illicit nuclear or radioactive material for the purposes of non-proliferations and attribution. One technique commonly employed for gathering nuclear forensics information is isotope analysis. At present, the state-of-the-art methodology for obtaining isotopic distributions is thermal ionization mass spectrometry (TIMS). Although TIMS is highly accurate at determining isotope distributions, the technique requires an elementally pure sample to perform the measurement. The required radiochemical separations give rise to sample preparation times that can be in excess of one to two weeks. Clearly, the nuclear forensics community is in need of instrumentation and methods that can expedite their decision making process in the event of a radiological release or nuclear detonation. Accordingly, we are developing instrumentation that couples a high resolution IM drift cell to the front end of a MS. The IM cell provides a means of separating ions based upon their collision cross-section and mass-to-charge ratio (m/z). Two analytes with the same m/z, but with different collision cross-sections (shapes) would exit the cell at different times, essentially enabling the cell to function in a similar manner to a gas chromatography (GC) column. Thus, molecular and atomic isobaric interferences can be effectively removed from the ion beam. The mobility selected chemical species could then be introduced to a MS for high-resolution mass analysis to generate isotopic distributions of the target analytes. The outcome would be an IM/MS system capable of accurately measuring isotopic distributions while concurrently eliminating isobaric interferences and laboratory radiochemical sample preparation. The overall objective of this project is developing instrumentation and methods to produce near real-time isotope distributions with a modular mass spectrometric system that performs the required gas-phase chemistry and

  20. Xe isotopic abundances in enstatite meteorites and relations to other planetary reservoirs

    This paper describes the interpretation of xenon that was measured in the Abee meteorite. Reported Xe isotopic abundances in enstatite chondrites (EC's) show some variability, and this makes comparisons to other solar system reservoirs rather difficult. In contrast, we find uniform Xe isotopic abundances in the EC chondrite Abee for a variety of clasts, except for 128Xe and 129Xe, the isotopes affected by neutron capture in I and by extinct 129I. We report averages for the studied clasts which are consistent within error limits with OC-Xe and with the Q-Xe signature. On the other hand, the elemental abundance ratios Ar/Xe are variable between clasts. A strongly reducing environment which is indicated for enstatite meteorites was generally assumed to be consistent with conditions existing in the early inner solar system. Xe isotopic abundances in SNC meteorites from Mars and also those in some terrestrial wells show that distinct isotopic reservoirs coexisted on the same planets. In particular, the Xe isotopic signatures in terrestrial well gases show the presence of a minor distinct component in two of the reported four well gases. These authors suggested that the extra component represents solar Xe, but we show that also a meteoritic xenon reservoir of the Abee-Xe structure is an option. The reported Xe data in Ar-rich (subsolar) EC's show isotopic abundances slightly lighter than those in Abee-Xe, but the relative abundances of Ar, Kr, and Xe indicate only a minor component of elementally unfractionated solar Xe. The elemental ratios suggest rather a different origin for these gases: the loading of solar particles into grain surfaces during exposure at elevated temperatures during accretion of matter in the inner solar system. A model of this type was suggested for the accretion of gases now observed in the atmosphere on Venus. We note that disks of crystalline silicates (including enstatite and olivine) have been observed in T Tauri stars during their early

  1. Determination of isotope abundance and elemental concentration of lithium by thermal ionization mass spechometry

    An analytical method for the determination of the isotope abundance and elemental concentration of lithium by mass spectrometry has been developed. A study, envolving the optimization of the various experimental parameters aimed at reducing the isotope fractionation that occur during evaporation, has been made. The experimental parameters optimized are: type of filament arrangement, accelerating voltage of the ions, quantity and chemical form of the samples deposited and the temperature of ionization. The effect of isotope fractionation on the isotope ratio measurements has been studied and compared with the theoretical model of Kanno and correction has been applied based on the variation of the isotope ratio of lithium with the time of analysis. The concentration of lithium in a sample of uranyl nitrate and an U.S.G.S. rock standard has been determined by the mass spectrometric isotope dilution technique using a tracer enriched in lithium-6. (Author)

  2. Carbon and nitrogen biogeochemistry in the ocean: A study using stable isotope natural abundance

    Rau, G. H.; Desmarais, David J.

    1985-01-01

    Determining the biogeochemical pathways traveled by carbon and nitrogen in the ocean is fundamental to the understanding of how the ocean participates in the cycling of these elements within the biosphere. Because biological production, metabolism, and respiration can significantly alter the natural abundance of C-13 and N-15, these abundances can provide important information about the nature of these biological processes and their variability in the marine environment. The research initially seeks to characterize the spatial and temporal patterns of stable isotope abundances in organic matter, and to relate these abundances to C and N biogeochemical processes within selected areas of the northeastern Pacific Ocean.

  3. Determination of relative plutonium isotopic abundances by gamma-ray spectrometry

    Plutonium, a fissionable material and, consequently, a special nuclear material (SNM), must be accurately accounted for and safeguarded. Accountability of plutonium usually requires a measurement of the isotopic abundances as well as the elemental weight or concentration. Although mass spectrometers are commonly used to measure isotopic abundances, they require extensive preparation of the sample and destroy the sample during the analysis. The authors have developed techniques and computer programs have been developed to measure plutonium isotopic abundances by gamma-ray spectrometry, they have developed a methodology that is substantially different. The methods have been programmed into a computerized multigroup analysis (MGA) code. They routinely use the MGA program at Lawrence Livermore National Laboratory for analyzing metals, oxides, and solutions that are high in 239Pu content for materials accountability purposes. The program has also been put into routine use by the Euratom Safeguards Directorate and the international Atomic Energy Agency

  4. ICP-oa TOFMS utilisation to determine the Gd isotopic abundance in gadolinium nitrate

    This paper is describes the development of a method that should permit the determination of isotope abundance of gadolinium in gadolinium nitrate, used as burnable poison at Cernavoda NPP. To determine the isotopic abundance of gadolinium the inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometer (ICP-oa TOFMS) was used. The ICP-oa TOFMS allows the elimination of noise associated with instrumental drift and instability (flicker noise). The absence of flicker noise in the ICP-oa TOFMS means that the isotope ratios can be measured up to the statistical limit of ion counting. With TOFMS, each spectrum acquired represents signals from ions extracted from the plasma during the same time interval, formed from identical plasma and sample introduction events. Therefore, the ICP-oa TOFMS, Optimass 8000, has been successfully used for isotope ratio measurements of Gd in gadolinium nitrate [Gd (NO3)3 x 6H2O] sample solutions. (authors)

  5. Isotope Abundances of Solar Coronal Material Derived from Solar Energetic Particle Measurements

    Mewaldt, R.A; Stone, E. C.

    1987-01-01

    Coronal isotopic abundances for the elements He, C, N, O, Ne, and Mg are derived from previously published measurements of the isotopic composition of solar energetic particles by first measuring, and then correcting for, the charge-to-mass-dependent fractionation due to solar flare acceleration and propagation processes. The resulting coronal composition generally agrees with that of other samples of solar system material, but the previously noted difference between the solar flare and solar...

  6. Measurement of plutonium and uranium isotopic abundances by gamma-ray spectrometry

    The isotopic composition of plutonium and uranium is needed for purposes of sample confirmation, or for interpreting results from calorimeters or neutron-coincidence measurement instruments to determine nuclear material mass. The authors have developed measurement methods and computer codes utilizing high-resolution gamma-ray spectrometry to measure the relative isotopic abundances of plutonium and uranium in various forms nondestructively. The computer codes, known as MGA and MGAU, have unique analysis methodologies that the authors briefly describe in this paper

  7. Measurement of plutonium and uranium isotopic abundances by gamma-ray spectrometry

    Ruhter, W.D. [Lawrence Livermore National Lab., CA (United States); Gunnink, R. [Gunnink (Ray), Fremont, CA (United States)

    1996-02-01

    The isotopic composition of plutonium and uranium is needed for purposes of sample confirmation, or for interpreting results from calorimeters or neutron-coincidence measurement instruments to determine nuclear material mass. The authors have developed measurement methods and computer codes utilizing high-resolution gamma-ray spectrometry to measure the relative isotopic abundances of plutonium and uranium in various forms nondestructively. The computer codes, known as MGA and MGAU, have unique analysis methodologies that the authors briefly describe in this paper.

  8. Determination of 235U isotope abundance by measuring selected pairs of fission products

    A new method to determine experimentally the isotopic abundance of uranium has been developed by measuring the ratios of selected fission product pairs. The relationship between the 235U abundance and the ratios of 14 MeV neutron-induced fission products, which are N(3892Sr)/N(44105Ru) and N(3892Sr)/N(53135I), have been obtained. The results of 4 test samples show that the relative deviations between the measured and the reference 235U abundances are less than ±3%.

  9. Measurement of the isotopic abundance of boron-10 by inductively coupled plasma-quadrupole mass spectrometry

    This article describes the method for measuring the isotopic abundance of 10B in nuclear grade boron carbide using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The results of investigation revealed that both the integration time and the dwell time have a major influence on the reproducibility of ICP-QMS measurements. As a result of optimization of the measurement conditions, reproducibility below 0.2% relative standard deviation (RSD) (0.17% RSD maximum) was achieved. In addition, the measured value of the isotopic abundance of 10B for each sample well agreed with the values measured by the TIMS. Thus, the method described in the present investigation was very effective in the analysis of isotopic abundance of 10B in B4C or H3BO3. The results of this study suggest that ICP-QMS could be applied to the precise analysis of the isotopic abundance of 10B required in the field of nuclear applications. (author)

  10. A shielded SIMS in CEA: a new tool for the low abundant isotopes characterization

    In the framework of studies on long term behaviour of nuclear fuel, the inventory of some isotopes with a low abundance is necessary (iodine 129 or carbon 14 for example). Up to now little attention was paid to these isotopes in the nuclear fuel because they have nearly no influence on the nuclear fuel behavior in irradiation conditions, despite their interest for waste studies. Recently a shielded SIMS was installed in the LECA-STAR facility which enables the detection of some isotopes up to the ppb. Its capabilities were tested with iodine and carbon in irradiated nuclear fuel. It is demonstrated that these elements can have different chemical forms and non homogeneous distribution within the UO2 ceramics. These results can provide a more realistic description of the behaviour of these elements. The SIMS characterization can be applied on numerous low abundant radio-nuclide and different solid materials. (authors)

  11. Determination of 235U isotope abundance by difference method of fission yield

    Background: Determination of the uranium isotope abundance ratio of fuel pins is a significant stage for the quality control in safe operations of reactor. Purpose: The aim is to establish a method to examine the 235U abundance of fuel rod with fast neutron as an excitation source. Methods: Taking the fission-yield ratios of Y-bar88Rb/Y-bar104Tc and Y-bar92Sr/Y-bar104Tc as the subjects of research, the relation curves between the average yield ratios and the 235U isotopic abundance as well as the expressions Y-bar1/Y-bar2=f(H0), in which the average yield ratio (Y-bari/Y-barj ) is a function of the 235U isotopic abundance (H0), were obtained and presented based on the previous studies. Results: In order to testify the accuracy of the method, the simulation sample of 72.2% is measured by working curve, and RSD is less than 2%. Within the limit of error, the results of sample analysis are in correspondence with those of passive gamma ray method. Conclusion: All of these results indicate that the method is feasible to determine the 235U abundance of fuel rod. (authors)

  12. Improve accuracy and sensibility in glycan structure prediction by matching glycan isotope abundance

    Highlights: ► A glycan isotope pattern recognition strategy for glycomics. ► A new data preprocessing procedure to detect ion peaks in a giving MS spectrum. ► A linear soft margin SVM classification for isotope pattern recognition. - Abstract: Mass Spectrometry (MS) is a powerful technique for the determination of glycan structures and is capable of providing qualitative and quantitative information. Recent development in computational method offers an opportunity to use glycan structure databases and de novo algorithms for extracting valuable information from MS or MS/MS data. However, detecting low-intensity peaks that are buried in noisy data sets is still a challenge and an algorithm for accurate prediction and annotation of glycan structures from MS data is highly desirable. The present study describes a novel algorithm for glycan structure prediction by matching glycan isotope abundance (mGIA), which takes isotope masses, abundances, and spacing into account. We constructed a comprehensive database containing 808 glycan compositions and their corresponding isotope abundance. Unlike most previously reported methods, not only did we take into count the m/z values of the peaks but also their corresponding logarithmic Euclidean distance of the calculated and detected isotope vectors. Evaluation against a linear classifier, obtained by training mGIA algorithm with datasets of three different human tissue samples from Consortium for Functional Glycomics (CFG) in association with Support Vector Machine (SVM), was proposed to improve the accuracy of automatic glycan structure annotation. In addition, an effective data preprocessing procedure, including baseline subtraction, smoothing, peak centroiding and composition matching for extracting correct isotope profiles from MS data was incorporated. The algorithm was validated by analyzing the mouse kidney MS data from CFG, resulting in the identification of 6 more glycan compositions than the previous annotation

  13. Improve accuracy and sensibility in glycan structure prediction by matching glycan isotope abundance

    Xu Guang [College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan (China); National Research Council Canada, Ottawa, Ont., K1A 0R6 (Canada); Liu Xin [College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan (China); Liu Qingyan [National Research Council Canada, Ottawa, Ont., Canada K1A 0R6 (Canada); Zhou Yanhong, E-mail: yhzhou@mail.hust.edu.cn [College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan (China); Li Jianjun, E-mail: Jianjun.Li@nrc-cnrc.gc.ca [National Research Council Canada, Ottawa, Ont., Canada K1A 0R6 (Canada)

    2012-09-19

    Highlights: Black-Right-Pointing-Pointer A glycan isotope pattern recognition strategy for glycomics. Black-Right-Pointing-Pointer A new data preprocessing procedure to detect ion peaks in a giving MS spectrum. Black-Right-Pointing-Pointer A linear soft margin SVM classification for isotope pattern recognition. - Abstract: Mass Spectrometry (MS) is a powerful technique for the determination of glycan structures and is capable of providing qualitative and quantitative information. Recent development in computational method offers an opportunity to use glycan structure databases and de novo algorithms for extracting valuable information from MS or MS/MS data. However, detecting low-intensity peaks that are buried in noisy data sets is still a challenge and an algorithm for accurate prediction and annotation of glycan structures from MS data is highly desirable. The present study describes a novel algorithm for glycan structure prediction by matching glycan isotope abundance (mGIA), which takes isotope masses, abundances, and spacing into account. We constructed a comprehensive database containing 808 glycan compositions and their corresponding isotope abundance. Unlike most previously reported methods, not only did we take into count the m/z values of the peaks but also their corresponding logarithmic Euclidean distance of the calculated and detected isotope vectors. Evaluation against a linear classifier, obtained by training mGIA algorithm with datasets of three different human tissue samples from Consortium for Functional Glycomics (CFG) in association with Support Vector Machine (SVM), was proposed to improve the accuracy of automatic glycan structure annotation. In addition, an effective data preprocessing procedure, including baseline subtraction, smoothing, peak centroiding and composition matching for extracting correct isotope profiles from MS data was incorporated. The algorithm was validated by analyzing the mouse kidney MS data from CFG, resulting in the

  14. The Barium Isotopic Abundance in the Metal-Poor Star HD140283

    Collet, R; Nissen, P E

    2008-01-01

    We derive the mixture of odd to even barium isotopes in the atmosphere of the metal-poor subgiant HD140283 from the analysis of the Ba II transition at 455.4 nm in a high-resolution high signal-to-noise spectrum of the star. The detailed shape of this spectral line depends on the relative contributions of odd and even isotopes via isotopic and hyperfine splitting. We measure the fractional abundance of odd Ba isotopes by modelling the formation of the Ba II 455.4 nm line profile with the use of both a classical 1D hydrostatic and a 3D hydrodynamical model atmosphere of HD140283. We interpret the results in terms of contributions by the slow (s-) and rapid (r-) neutron-capture processes to the isotopic mix. While the result of the 1D analysis of the Ba II feature indicates a (64 +/- 36)% contribution of the r-process to the isotopic mix, the 3D analysis points toward a mere (15 +/- 34)% contribution from this process, that is consistent with a solar-like mixture of barium isotopes.

  15. Accurate determination of the 235U isotope abundance by gamma spectrometry

    The purpose of this manual is to serve as guide in applications of the Certified Reference Material EC-NRM-171/NBS-SRM-969 for accurate U-235 isotope abundance measurements on bulk uranium samples by means of gamma spectrometry. The manual provides a thorough description of this non-destructive assay technique. Crucial measurement parameters affecting the accuracy of the gamma-spectrometric U-235 isotope abundance determination are discussed in detail and, whereever possible, evaluated quantitatively. The correction terms and tolerance limits given refer both to physical and chemical properties of the samples under assay and to relevant parameters of typical measurement systems such as counting geometry, signal processing, data evaluation and calibration. (orig.)

  16. Enhancement of the isotopic abundance sensitivity of mass spectrometry by Doppler-free resonance ionization

    The use of two-photon Doppler-free excitation in atomic resonance ionization offers the possibility of considerable enhancement of the isotopic abundance sensitivity of conventional mass spectrometry. In some applications of interest, e.g. carbon dating, this technique may provide sensitivity comparable to that presently attained by accelerator-based high energy mass spectrometry. The basic physics underlying the method is discussed and preliminary experimental work on three-photon ionization of atomic carbon is described. (author)

  17. A physicochemical study on isotope abundance ratio of lithium contained in a few minerals of pegmatite

    Lithium samples for mass spectrometric measurement were prepared from biotite, quartz, albite, and microcline which were separated each other from pegmatite in Naegi, Nakatsugawa, Gifu Prefecture, Japan. Lithium isotope abundance ratio (7Li/6Li) of the lithium samples were measured by mass spectrometry using surface ionization ion source. Significant difference has been found among the (7Li/6Li) values of biotite, quartz, albite, and microcline samples. The results have been briefly discussed from physicochemical and geological viewpoint. (author)

  18. Investigation of Isotopic Abundance Ratio of Biofield Treated Phenol Derivatives Using Gas Chromatography-Mass Spectrometry

    Trivedi, Mahendra Kumar

    2015-01-01

    Butylatedhydroxytoluene (BHT) and 4-methoxyphenol (4-MP) are phenol derivatives that are generally known for their antioxidant properties and depigmenting activities. The aim of this study was to evaluate the impact of biofield energy treatment on the isotopic abundance of BHT and 4-MP using gas chromatography-mass spectrometry (GC-MS). BHT and 4-MP samples were divided into two parts: control and treated. The control group remained untreated while the treated group was subjected to Mr. Trive...

  19. Application of mass-predictions to isotope-abundances in breeder-reactor cores

    The decay-heat and isotope composition of breeder reactor-cores is calculated at normal shut-down, and a core disintegration event. Using the ORIGRN-code, the influence of the most neutron-rich fission-yield nuclei is studied. Their abundances depend on the assumption about the nuclear data (mass and half-lives). The total decay-heat is not changed from any technically view-point. (orig.)

  20. Application of mass-predictions to isotope-abundances in breeder-reactor cores

    Kirchner, G

    1981-01-01

    The decay-heat and isotope composition of breeder reactor-cores is calculated at normal shut-down, and a core disintegration event. Using the ORIGEN-code, the influence of the most neutron-rich fission-yield nuclei is studied. Their abundances depend on the assumption about the nuclear data (mass and half-lives). The total decay-heat is not changed from any technical viewpoint. (15 refs).

  1. Boron abundances and isotopic ratios of olivine grains on Itokawa returned by the Hayabusa spacecraft

    Fujiya, Wataru; Hoppe, Peter; Ott, Ulrich

    2016-07-01

    We report the B abundances and isotopic ratios of two olivine grains from the S-type asteroid Itokawa sampled by the Hayabusa spacecraft. Olivine grains from the Dar al Gani (DaG) 989 LL6 chondrite were used as a reference. Since we analyzed polished thin sections in both cases, we expect the contribution from the solar wind B (rich in 10B) to be minimal because the solar wind was implanted only within very thin layers of the grain surface. The Itokawa and DaG 989 olivine grains have homogeneous B abundances (~400 ppb) and 11B/10B ratios compatible with the terrestrial standard and bulk chondrites. The observed homogeneous B abundances and isotopic ratios of the Itokawa olivine grains are likely the result of thermal metamorphism which occurred in the parent asteroid of Itokawa, which had a similar composition as LL chondrites. The chondritic B isotopic ratios of the Itokawa samples suggest that they contain little cosmogenic B (from cosmic-ray spallation reactions) rich in 10B. This observation is consistent with the short cosmic-ray exposure ages of Itokawa samples inferred from the small concentrations of cosmogenic 21Ne. If other Itokawa samples have little cosmogenic B as well, the enrichment in 10B found previously on the surface of another Itokawa particle (as opposed to the bulk grain study here) may be attributed to implanted solar wind B.

  2. Absolute and Relative Isotope Abundances Measured by Tunable Diode Laser Spectroscopy

    Tucker, George Franklin

    The potential for measuring absolute and relative isotope abundances by high resolution spectroscopy with tunable diode lasers as sources was studied. In order to achieve the sensitivity necessary to determine the absolute abundances of molecules containing long-lived radionuclides such as ('14)C an ('129)I, a resonant spectrophone based on the photoacoustic effect was used for detection. For safety, NH(,3) was used as a sample with air as a buffer gas when characterizing the performance of the TDL-spectrophone system. Frequency modulation of the TDL was employed. The optimum operating pressure was found to be 6.6 kPa(50 Torr). Substitution of Kr as a buffer gas yielded a fourfold increase in signal. It is estimated that with currently available TDLs a photoacoustic spectrometer should be capable of detecting ('14)CO(,2) and CH('129)I at the levels present in nuclear reactor containment gases. An isotope shift of CH(,3)('129) I relative to CH(,3)('127)I in the (nu)(,6) band of (0.0135 (+OR-) 0.0006) cm('-1) was measured by TDL linear absorption spectroscopy. To perform relative isotope abundance measurements a TDL was tuned over two adjacent, but well-resolved, rotation -vibration absorption lines, one of each isotopic species, while the transmitted radiation was monitored with a HgCdTe detector. The P(26) line of the (nu)(,1) band of N(,2)('18)O at 1225.3671 cm('-1) and the P(63) line of the (nu)(,1) band of N(,2)('16)O at 1225.4879 cm('-1) were chosen, for their line strength ratio is inversely proportional to the ratio of their natural abundances, and thereby yielded approximately equal absorbance for each isotopic species. A double-beam, single-detector spectrometer with wavelength modulation to minimize the effects of laser power and cell temperature fluctuations, has been adapted for use with a TDL. After samples of known ('18)O enrichment were used to calibrate the spectrometer, the (delta)('18)O of tropospheric N(,2)O was measured to be (8.05 (+OR-) 0

  3. Mercury Abundances and Isotopic Compositions in the Murchison (CM) and Allende (CV)Carbonaceous Chondrites

    Lauretta, D. S.; Klaue, B.; Blum, J. D.; Buseck, P. R.

    2001-01-01

    The abundance and isotopic composition of Hg was determined in bulk samples of both the Murchison (CM) and Allende (CV) carbonaceous chondrites using single- and multi-collector inductively coupled plasma mass spectrometry (ICP-MS). The bulk abundances of Hg are 294 6 15 ng/g in Murchison and 30.0 6 1.5 ng/g in Allende. These values are within the range of previous measurements of bulk Hg abundances by neutron activation analysis (NAA). Prior studies suggested that both meteorites contain isotopically anomalous Hg, with d l 96/202Hg values for the anomalous, thermal-release components from bulk samples ranging from 2260 %o to 1440 9/00 in Murchison and from 2620 9/00 to 1540 9/00 in Allende (Jovanovic and Reed, 1976a; 1976b; Kumar and Goel, 1992). Our multi-collector ICP-MS measurements suggest that the relative abundances of all seven stable Hg isotopes in both meteorites are identical to terrestrial values within 0.2 to 0.5 9/00m. On-line thermal-release experiments were performed by coupling a programmable oven with the singlecollector ICP-MS. Powdered aliquots of each meteorite were linearly heated from room temperature to 900 C over twenty-five minutes under an Ar atmosphere to measure the isotopic composition of Hg released fiom the meteorites as a h c t i o n of temperature. In separate experiments, the release profiles of S and Se were determined simultaneously with Hg to constrain the Hg distribution within the meteorites and to evaluate the possibility of Se interferences in previous NAA studies. The Hg-release patterns differ between Allende and Murchison. The Hg-release profile for Allende contains two distinct peaks, at 225" and 343"C, whereas the profile for Murchison has only one peak, at 344 C. No isotopically anomalous Hg was detected in the thermal-release experiments at a precision level of 5 to 30 9/00, depending on the isotope ratio. In both meteorites the Hg peak at ;340"C correlates with a peak in the S-release profile. This correlation

  4. Isotope abundance measurements. A key to an exotic problem solving: a review

    Since the paleotemperature measurements carried out by Urey and Epstein, early in the nineteen fifties, isotope abundance measurements have developed outside the boundary of research. They have become in the European Union an official method for food analysis. In France, customs employ them to find the origin of seized drugs. Frauds, such as 'chaptalization' (i.e. adding sugar to wine), are detected by isotope analysis. Disulfur monoxide, S2O, was discovered during the investigation of the mass spectrometer background when analysing sulphur dioxide isotope composition from masses 64 to 72. At the request of our meteorological bureau we investigated the formation and isotopic compositions of hailstones. It was possible to correlate deuterium contents to the formation temperature and to draw trajectories of hailstones within clouds where they grew. A growth model, NMR (Nief, Merlivat, Roth), was established. 18O and deuterium analysis were carried out on the same hailstone samples to validate this model, that implied equilibrium between vapour and condensed phases within hail forming clouds. Additional confirmation of some results could be found in tritium measurements. Also, the formation of deuterium by spallation had a further consequence: the study of this formation by reaction of the 'solar wind' on meteorites that can be used to measure the time spent by a meteorite within the solar system. We shall briefly discuss, among less frequent applications of isotope measurements, the losses of water, from closed or semi closed water pools, by evaporation and other causes. Such investigations have mainly been performed in arid countries. (author)

  5. Line formation in solar granulation VII. CO lines and the solar C and O isotopic abundances

    Scott, P C; Grevesse, N; Sauval, A J; Asplund, Martin; Grevesse, Nicolas; Scott, Patrick C.

    2006-01-01

    CO spectral line formation in the Sun has long been a source of consternation for solar physicists, as have the elemental abundances it seems to imply. We modelled solar CO line formation using a realistic, ab initio, time-dependent 3D radiative-hydrodynamic model atmosphere. Results were compared with observations from the space-based ATMOS experiment. We employed weak 12C16O, 13C16O and 12C18O lines from the fundamental and first overtone bands to determine the solar carbon abundance, as well as the 12C/13C and 16O/18O isotopic ratios. A weighted carbon abundance of log epsilonC = 8.39 +-0.05 was found. We note with satisfaction that the derived abundance is identical to our recent 3D determination based on CI, [C I], C2 and CH lines. Identical calculations were carried out using 1D models, but only the 3D model was able to produce abundance agreement between different CO lines and the other atomic and molecular diagnostics. Solar 12C/13C and 16O/18O ratios were measured as 86.8+3.9-3.7 (delta13C = 30+46-44...

  6. Discussion on the Key Factors of Abundance Ratios About Zn Isotope Measurement

    The application of Zn isotope analysis is well known in geochemistry and diet study. An inter-lab comparison of five samples with isotopic ratio covering from 0.02 to 15.00 was organized in order to develop measurement ability and keep consistency of the results of isotopic ratios measurement among the participants. Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) and multi-collector thermal ionization mass spectrometry (MC-TIMS) were used. For MC-ICP-MS, blank-corrected and blank-no corrected results were submitted. For MC-TIMS, total evaporation method (TE) was applied to the samples while a certified reference material IRMM3702 was analyzed together. All the results showed that the uncertainties were 1.29%-0.03% for 64Zn/66Zn, and the uncertainty was obviously relative to isotopic abundances. The blank-corrected and blank-no corrected and the influence of blank and non-linear of K factor of mass discrimination for MC-ICP-MS were convinced of contributing to the unsatisfied uncertainties. (authors)

  7. On line data acquisition and processing system for isotope abundance measurements using a spectrometer

    A system built using a TDC-312 computer for the automation of the Varian MAT CH-5 mass spectrometer for isotopic analysis is described. Salient feature of this automation is that software forms a major part of the system. A versatile computer program has been developed which can be used for the isotope abundance measurements of any element without interfering with the software of the system. The adjustment of ranges (gains) in between the peaks and updating of ranges, if required, is also performed by the computerised system. This has reduced the human intervention and the results are less prone to human error. Incidentally, this has also relieved the personnel of the strenuous manual work involved in the spectrum analysis. (auth.)

  8. Abundances in red giant stars - Carbon and oxygen isotopes in carbon-rich molecular envelopes

    Wannier, P. G.; Sahai, R.

    1987-01-01

    Millimeter-wave observations have been made of isotopically substituted CO toward the envelopes of 11 carbon-rich stars. In every case, C-13O was detected and model calculations were used to estimate the C-12/C-13 abundance ratio. C-17O was detected toward three, and possibly four, envelopes, with sensitive upper limits for two others. The CO-18 variant was detected in two envelopes. New results include determinations of oxygen isotopic ratios in the two carbon-rich protoplanetary nebulae CRL 26688 and CRL 618. As with other classes of red giant stars, the carbon-rich giants seem to be significantly, though variably, enriched in O-17. These results, in combination with observations in interstellar molecular clouds, indicate that current knowledge of stellar production of the CNO nuclides is far from satisfactory.

  9. The determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium

    The mass spectrometric determination of minor abundant isotopes, 234U and 236U in naturally occurring uranium materials requires instruments of high abundance sensitivity and the use of highly sensitive detection systems. In this study the thermal ionisation mass spectrometer Finnigan MAT 262RPQ was used. It was equipped with 6 Faraday cups and a Secondary Electron Multiplier (SEM), which was operated in pulse counting mode for the detection of extremely low ion currents. The dynamic measurement range was increased considerably combining these two different detectors. The instrument calibration was performed carefully. The linearity of each detector, the deadtime of the ion counting detector, the detector normalisation factor, the baseline of each detector and the mass discrimination in the ion source were checked and optimised. A measurement technique based on the combination of a Gas Source Mass Spectrometry (GSMS) and a Thermal Ionisation Mass Spectrometry (TIMS) was developed for the accurate determination of isotopic composition in naturally occurring uranium materials. Because the expected ratio of n(234U)/n(238U) exceeded the dynamic measurement range of the Faraday detectors of the TIMS instrument, an experimental design using a combination of two detectors was developed. The n(234U)/n(235U) and n(236U)/n(235U) ratios were determined using ion counting in combination with the decelerating device. The n(235U)/n(238U) ratio was determined by the Faraday detector. This experimental design allowed the detector cross calibration to be circumvented. Precisions of less than 1 percent for the n(234U)/n(235U) ratios and 5-25 percent for the n(236U)/n(235U) ratios were achieved. The purpose of the study was to establish a register of isotopic signatures for natural uranium materials. The amount ratio, and isotopic composition of 18 ore concentrates, collected by the International Atomic Energy Agency (IAEA) from uranium milling and mining facilities (Australia

  10. The determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium

    Ovaskainen, R

    1999-11-01

    The mass spectrometric determination of minor abundant isotopes, {sup 234}U and {sup 236}U in naturally occurring uranium materials requires instruments of high abundance sensitivity and the use of highly sensitive detection systems. In this study the thermal ionisation mass spectrometer Finnigan MAT 262RPQ was used. It was equipped with 6 Faraday cups and a Secondary Electron Multiplier (SEM), which was operated in pulse counting mode for the detection of extremely low ion currents. The dynamic measurement range was increased considerably combining these two different detectors. The instrument calibration was performed carefully. The linearity of each detector, the deadtime of the ion counting detector, the detector normalisation factor, the baseline of each detector and the mass discrimination in the ion source were checked and optimised. A measurement technique based on the combination of a Gas Source Mass Spectrometry (GSMS) and a Thermal Ionisation Mass Spectrometry (TIMS) was developed for the accurate determination of isotopic composition in naturally occurring uranium materials. Because the expected ratio of n({sup 234}U)/n({sup 238}U) exceeded the dynamic measurement range of the Faraday detectors of the TIMS instrument, an experimental design using a combination of two detectors was developed. The n({sup 234}U)/n({sup 235}U) and n({sup 236}U)/n({sup 235}U) ratios were determined using ion counting in combination with the decelerating device. The n({sup 235}U)/n({sup 238}U) ratio was determined by the Faraday detector. This experimental design allowed the detector cross calibration to be circumvented. Precisions of less than 1 percent for the n({sup 234}U)/n({sup 235}U) ratios and 5-25 percent for the n({sup 236}U)/n({sup 235}U) ratios were achieved. The purpose of the study was to establish a register of isotopic signatures for natural uranium materials. The amount ratio, and isotopic composition of 18 ore concentrates, collected by the International

  11. An high resolution FDIRC for the measurement of cosmic-ray isotopic abundances

    Marrocchesi, P. S.; Bagliesi, M. G.; Batkov, K.; Bigongiari, G.; Kim, M.Y.; Maestro, P.

    2011-01-01

    Abstract Measurements of the relative abundance of cosmic isotopes and of the energy dependence of their fluxes may clarify our present understanding on the confinement time of charged cosmic rays in the Galaxy. Experimental studies of these propagation clocks have been carried out by balloon and space missions at energies of a few 100 MeV/amu by means of detection techniques based on multiple dE/dx sampling, coupled with a measurement of the energy released in a thick absorber. At...

  12. Influence of Biofield Energy Treatment on Isotopic Abundance Ratio in Aniline Derivatives

    Mahendra Kumar Trivedi; Alice Branton; Dahryn Trivedi; Gopal Nayak

    2015-01-01

    The aim of this study was to evaluate the impact of biofield energy treatment on the isotopic abundance of 13C/12C or 2H/1H or 15N/14N ≡ (PM+1)/PM in aniline; and (PM+1)/PM and 81Br/79Br ≡ (PM+2)/PM in 4-bromoaniline using Gas Chromatography-Mass Spectrometry (GC-MS). Aniline and 4-bromoaniline samples were divided into two parts: control and treated. The control part remained as untreated, while the treated part was subjected to Mr. Trivedi’s biofield energy treatment. The ...

  13. Determination of 13C and 18O isotopic abundances of carboxyl substances; application to amino acids

    Flash pyrolysis of organic acids or of their salts gives off carbon dioxide which can be analysed by mass spectrometry for 13C and 18O abundance. This principle has been applied to Cd13C18O3 using an induction furnace, and used to determine the 13C and 18O content of the carboxylic group of some amino acids. The technique described has many advantages over the classical pyrolysis methods using sealed tubes. It is rapid and simple and especially effective in determining the isotopic composition of hygroscopic carboxyl substances. (U.K.)

  14. The evolution of the global selenium cycle: Secular trends in Se isotopes and abundances

    Stüeken, E. E.; Buick, R.; Bekker, A.; Catling, D.; Foriel, J.; Guy, B. M.; Kah, L. C.; Machel, H. G.; Montañez, I. P.; Poulton, S. W.

    2015-08-01

    The Earth's surface has undergone major transitions in its redox state over the past three billion years, which have affected the mobility and distribution of many elements. Here we use Se isotopic and abundance measurements of marine and non-marine mudrocks to reconstruct the evolution of the biogeochemical Se cycle from ∼3.2 Gyr onwards. The six stable isotopes of Se are predominantly fractionated during redox reactions under suboxic conditions, which makes Se a potentially valuable new tool for identifying intermediate stages from an anoxic to a fully oxygenated world. δ82/78Se shows small fractionations of mostly less than 2‰ throughout Earth's history and all are mass-dependent within error. In the Archean, especially after 2.7 Gyr, we find an isotopic enrichment in marine (+0.37 ± 0.27‰) relative to non-marine samples (-0.28 ± 0.67‰), paired with increasing Se abundances. Student t-tests show that these trends are statistically significant. Although we cannot completely rule out the possibility of volcanic Se addition, these trends may indicate the onset of oxidative weathering on land, followed by non-quantitative reduction of Se oxyanions during fluvial transport. The Paleoproterozoic Great Oxidation Event (GOE) is not reflected in the marine δ82/78Se record. However, we find a major inflection in the secular δ82/78Se trend during the Neoproterozoic, from a Precambrian mean of +0.42 ± 0.45‰ to a Phanerozoic mean of -0.19 ± 0.59‰. This drop probably reflects the oxygenation of the deep ocean at this time, stabilizing Se oxyanions throughout the water column. Since then, reduction of Se oxyanions has likely been restricted to anoxic basins and diagenetic environments in sediments. In light of recent Cr isotope data, it is likely that oxidative weathering before the Neoproterozoic produced Se oxyanions in the intermediate redox state SeIV, whereas the fully oxidized species SeVI became more abundant after the Neoproterozoic rise of

  15. Characterizing uranium oxide reference particles for isotopic abundances and uranium mass by single particle isotope dilution mass spectrometry

    Highlights: ► A method to quantify the U mass in single micron particles by ID-TIMS was developed. ► Well-characterized monodisperse U-oxide particles produced by an aerosol generator were used. ► A linear correlation between the mass of U and the volume of particle(s) was found. ► The method developed is suitable for determining the amount of U in a particulate reference material. - Abstract: Uranium and plutonium particulate test materials are becoming increasingly important as the reliability of measurement results has to be demonstrated to regulatory bodies responsible for maintaining effective nuclear safeguards. In order to address this issue, the Institute for Reference Materials and Measurements (IRMM) in collaboration with the Institute for Transuranium Elements (ITU) has initiated a study to investigate the feasibility of preparing and characterizing a uranium particle reference material for nuclear safeguards, which is finally certified for isotopic abundances and for the uranium mass per particle. Such control particles are specifically required to evaluate responses of instruments based on mass spectrometric detection (e.g. SIMS, TIMS, LA-ICPMS) and to help ensuring the reliability and comparability of measurement results worldwide. In this paper, a methodology is described which allows quantifying the uranium mass in single micron particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS). This methodology is characterized by substantial improvements recently achieved at IRMM in terms of sensitivity and measurement accuracy in the field of uranium particle analysis by TIMS. The use of monodisperse uranium oxide particles prepared using an aerosol generation technique developed at ITU, which is capable of producing particles of well-characterized size and isotopic composition was exploited. The evidence of a straightforward correlation between the particle volume and the mass of uranium was demonstrated in this study

  16. Study of isotopic fractions and abundances of the neutron-capture elements in HD 175305

    Zhang, Jiang; Zhang, Bo; 10.1111/j.1365-2966.2009.15947.x

    2010-01-01

    The chemical abundances of metal-poor stars are excellent sources of information for setting new constraints on models of Galactic chemical evolution at low metallicities. In this paper we present an attempt to fit the elemental abundances observed in the bright, metal-poor giant HD 175305, and derive isotopic fractions using a parametric model. The observed abundances can be wellmatched by the combined contributions froms- and r-processmaterial. The component coefficients of the r- and s-processes are C1 = 3.220 and C3 = 1.134, respectively. The Smisotopic fraction in this star where the observed neutron-capture elements are produced is predicted to be f 152+154 =0.582,which suggests that, even though the r-process is predominantly responsible for the synthesis of the neutron-capture elements in the early Galaxy, the onset of the s-process had already occurred at this metallicity of [Fe/H] = -1.6.

  17. ANALYSIS OF RICIN TOXIN PREPARATIONS FOR CARBOHYDRATE AND FATTY ACID ABUNDANCE AND ISOTOPE RATIO INFORMATION

    Wunschel, David S.; Kreuzer-Martin, Helen W.; Antolick, Kathryn C.; Colburn, Heather A.; Moran, James J.; Melville, Angela M.

    2009-12-01

    employing a quadrupole MS system for compound identification and an isotope ratio MS for measuring the stable isotope ratios of deuterium and hydrogen (D/H) in fatty acids. Finally, the method for analyzing the compound abundance data is included. This study indicates that removal of ricinoleic acid is a conserved consequence of each processing step we tested. Furthermore, the stable isotope D/H ratio of ricinoleic acid distinguished between two of the three castor seed sources. Concentrations of arabinose, xylose, mannose, glucosamine and myo-inositol differentiated between crude or acetone extracted samples and samples produced by protein precipitation. Taken together these data illustrate the ability to distinguish between processes used to purify a ricin sample as well as potentially the source seeds.

  18. Evaluation of the Isotopic Abundance Ratio in Biofield Energy Treated Resorcinol Using Gas Chromatography-Mass Spectrometry Technique

    Trivedi, Mahendra; Branton, Alice; Trivedi, Dahryn; Nayak, Gopal

    2016-01-01

    The stable isotope ratio analysis is widely used in several scientific fields such as agricultural, food authenticity, biochemistry, metabolism, medical research, etc. Resorcinol is one of the most versatile chemicals used for the synthesis of several pharmaceuticals, dyes, polymers, organic compounds, etc. The current research work was designed to investigate the impact of the biofield energy treatment on the isotopic abundance ratios of 13C/12C or 2H/1H or 17O/16O (P 18O/16O (P M+1/PM) and ...

  19. Tunable diode laser spectroscopy of stable isotopic tracers - Detection and measurement of relative abundance of isotopic carbon monoxide

    A molecular absorption system using a tunable diode laser and a dual path length sample cell for stable isotopic tracer analysis has been developed. The high spectral resolution and power density of the laser allow real-time simultaneous detection of different isotopes with great specificity. And, the matched absorption path length cell simplifies signal processing and improves the accuracy in quantitative measurement by maintaining the same signal to noise ratio for vastly different isotopic concentrations. The principle and operation of the system are described using isotopic oxygen analysis in carbon monoxide as an illustrative example. The method is applicable to any sample that is or can be converted into an infrared active gas. 8 refs.; 4 figs

  20. Mass Accuracy and Isotopic Abundance Measurements for HR-MS Instrumentation: Capabilities for Non-Targeted Analyses

    Knolhoff, Ann M.; Callahan, John H.; Croley, Timothy R.

    2014-07-01

    The development of automated non-targeted workflows for small molecule analyses is highly desirable in many areas of research and diagnostics. Sufficient mass and chromatographic resolution is necessary for the detectability of compounds and subsequent componentization and interpretation of ions. The mass accuracy and relative isotopic abundance are critical in correct molecular formulae generation for unknown compounds. While high-resolution instrumentation provides accurate mass information, sample complexity can greatly influence data quality and the measurement of compounds of interest. Two high-resolution instruments, an Orbitrap and a Q-TOF, were evaluated for mass accuracy and relative isotopic abundance with various concentrations of a standard mixture in four complex sample matrices. The overall average ± standard deviation of the mass accuracy was 1.06 ± 0.76 ppm and 1.62 ± 1.88 ppm for the Orbitrap and the Q-TOF, respectively; however, individual measurements were ± 5 ppm for the Orbitrap and greater than 10 ppm for the Q-TOF. Relative isotopic abundance measurements for A + 1 were within 5% of the theoretical value if the intensity of the monoisotopic peak was greater than 1E7 for the Orbitrap and 1E5 for the Q-TOF, where an increase in error is observed with a decrease in intensity. Furthermore, complicating factors were found in the data that would impact automated data analysis strategies, including coeluting species that interfere with detectability and relative isotopic abundance measurements. The implications of these findings will be discussed with an emphasis on reasonable expectations from these instruments, guidelines for experimental workflows, data analysis considerations, and software design for non-targeted analyses.

  1. Mercury (Hg) in meteorites: variations in abundance, thermal release profile, mass-dependent and mass-independent isotopic fractionation

    Meier, Matthias M M; Marty, Bernard

    2016-01-01

    We have measured the concentration, isotopic composition and thermal release profiles of Mercury (Hg) in a suite of meteorites, including both chondrites and achondrites. We find large variations in Hg concentration between different meteorites (ca. 10 ppb to 14'000 ppb), with the highest concentration orders of magnitude above the expected bulk solar system silicates value. From the presence of several different Hg carrier phases in thermal release profiles (150 to 650 {\\deg}C), we argue that these variations are unlikely to be mainly due to terrestrial contamination. The Hg abundance of meteorites shows no correlation with petrographic type, or mass-dependent fractionation of Hg isotopes. Most carbonaceous chondrites show mass-independent enrichments in the odd-numbered isotopes 199Hg and 201Hg. We show that the enrichments are not nucleosynthetic, as we do not find corresponding nucleosynthetic deficits of 196Hg. Instead, they can partially be explained by Hg evaporation and redeposition during heating of ...

  2. On-line analytical system developed for the ACEP to determine uranium concentration and uranium isotopic abundance ratio

    An on-line analytical system was developed to rapidly determine total uranium concentration and isotopic abundance ratio of 235U to 238U in a uranium solution which passes through a pipe in the chemical exchange uranium enrichment process. The isotopic abundance ratio is calculated by time with a computer using two analytical results, the determination of 235U and that of total uranium. A new method, in which the concentration of uranium could be quickly measured by detecting the absorption of γ-rays due to uranium, was investigated for the determination of uranium. The concentration of 235U was measured by the 185 keV of γ-rays obtained from the disintegration of 235U. The reproducibility of the isotopic abundance ratio analysis was improved less than 2% with relative standard deviation when more than 0.1 mol·dm-3 of natural uranium was analyzed. The analytical information on uranium can be obtained without any treatment in the enrichment equipment. (author)

  3. CNO abundances and carbon isotope ratios in evolved stars of the open clusters NGC 2324, NGC 2477, and NGC 3960

    Tautvaisiene, Grazina; Bragaglia, Angela; Randich, Sofia; Zenoviene, Renata

    2016-01-01

    Our main aim is to determine carbon-to-nitrogen and carbon isotope ratios for evolved giants in the open clusters NGC 2324, NGC 2477, and NGC 3960, which have turn-off masses of about 2 Msun, and to compare them with predictions of theoretical models. High-resolution spectra were analysed using a differential synthetic spectrum method. Abundances of carbon were derived using the C2 Swan (0,1) band heads at 5135 and 5635.5 A. The wavelength interval 7940-8130 A with strong CN features was analysed to determine nitrogen abundances and carbon isotope ratios. The oxygen abundances were determined from the [Oi] line at 6300 A. The mean values of the CNO abundances are [C/Fe]=-0.35+-0.06 (s.d.), [N/Fe]=0.28+-0.05, and [O/Fe]=-0.02+-0.10 in seven stars of NGC 2324; [C/Fe]=-0.26+-0.02, [N/Fe]=0.39+-0.04, and [O/Fe]=-0.11+-0.06 in six stars of NGC 2477; and [C/Fe]=-0.39+-0.04, [N/Fe]=0.32+-0.05, and [O/Fe]=-0.19+-0.06 in six stars of NGC 3960. The mean C/N ratio is equal to 0.92+-0.12, 0.91+-0.09, and 0.80+-0.13, resp...

  4. Characterization of uranium isotopic abundances in depleted uranium metal assay standard 115

    Certified reference material (CRM) 115, Uranium (Depleted) Metal (Uranium Assay Standard), was analyzed using a TRITON Thermal Ionization Mass Spectrometer to characterize the uranium isotope-amount ratios. The certified 235U/238U 'major' isotope-amount ratio of 0.0020337 (12) in CRM 115 was determined using the total evaporation (TE) and the modified total evaporation (MTE) analytical techniques. In the MTE method, the total evaporation process is interrupted on a regular basis to allow correction of background from peak tailing, internal calibration of the secondary electron multiplier detector versus the Faraday cups, peak-centering, and ion source re-focusing. For the 'minor' 234U/238U and 236U/238U isotope-amount ratio measurements using MTE, precision and accuracy comparable to conventional analyses are achieved, without compromising the quality of the 235U/238U isotope-amount ratios. Characterized values of the 234U/238U and 236U/238U isotope-amount ratios in CRM 115 are 0.000007545 (10) and 0.000032213 (84), respectively. The 233U/238U isotope-amount ratio in CRM 115 is estimated to be -9. The homogeneity of the CRM 115 materials is established through the absence of any statistically significant unit-to-unit variation in the uranium isotope-amount ratios. The measurements leading to the certification of uranium isotope-amount ratios are discussed. (author)

  5. Mercury (Hg) in meteorites: Variations in abundance, thermal release profile, mass-dependent and mass-independent isotopic fractionation

    Meier, Matthias M. M.; Cloquet, Christophe; Marty, Bernard

    2016-06-01

    We have measured the concentration, isotopic composition and thermal release profiles of Mercury (Hg) in a suite of meteorites, including both chondrites and achondrites. We find large variations in Hg concentration between different meteorites (ca. 10 ppb to 14,000 ppb), with the highest concentration orders of magnitude above the expected bulk solar system silicates value. From the presence of several different Hg carrier phases in thermal release profiles (150-650 °C), we argue that these variations are unlikely to be mainly due to terrestrial contamination. The Hg abundance of meteorites shows no correlation with petrographic type, or mass-dependent fractionation of Hg isotopes. Most carbonaceous chondrites show mass-independent enrichments in the odd-numbered isotopes 199Hg and 201Hg. We show that the enrichments are not nucleosynthetic, as we do not find corresponding nucleosynthetic deficits of 196Hg. Instead, they can partially be explained by Hg evaporation and redeposition during heating of asteroids from primordial radionuclides and late-stage impact heating. Non-carbonaceous chondrites, most achondrites and the Earth do not show these enrichments in vapor-phase Hg. All meteorites studied here have however isotopically light Hg (δ202Hg = ∼-7 to -1) relative to the Earth's average crustal values, which could suggest that the Earth has lost a significant fraction of its primordial Hg. However, the late accretion of carbonaceous chondritic material on the order of ∼2%, which has been suggested to account for the water, carbon, nitrogen and noble gas inventories of the Earth, can also contribute most or all of the Earth's current Hg budget. In this case, the isotopically heavy Hg of the Earth's crust would have to be the result of isotopic fractionation between surface and deep-Earth reservoirs.

  6. Natural abundance of N-15 and C-13 in fish tissues and the use of stable isotopes as dietary protein tracers in rainbow trout and gilthead sea bream

    Beltran, M; Fernandez-borras, J.; Medale, Francoise; Perez-sanchez, J.; Kaushik, Sadasivam; Blasco, J.

    2009-01-01

    For developing efficient diets, two sets of experiments examined whether the use and allocation of dietary protein can be traced by labelling with stable isotopes (N-15 and C-13) in two culture fish (Oncorhynchus mykiss and Sparus aurata). In the first experiment, natural abundance and tissue distribution of these isotopes were determined, by measuring the delta C-13 and delta N-15 values by isotopic ratio mass spectrometry, in fingerlings (14-17 g) adapted to diets differing in the percentag...

  7. Evaluation of Isotopic Abundance Ratio in Naphthalene Derivatives After Biofield Energy Treatment Using Gas Chromatography-Mass Spectrometry

    Mahendra Kumar Trivedi; Alice Branton; Dahryn Trivedi; Gopal Nayak

    2015-01-01

    Naphthalene and 2-naphthol are two naphthalene derivatives, which play important roles in the chemical and pharmaceutical industries. The aim of this study was to evaluate the impact of biofield energy treatment on the isotopic abundance of 13C/12C or 2H/1H and 18O/16O in naphthalene and 2-naphthol using gas chromatography-mass spectrometry (GC-MS). Naphthalene and 2-naphthol samples were divided into two parts: control and treated. The control group remained as untreated, while the treated g...

  8. Determination of Isotopic Abundance of 2H, 13C, 18O, and 37Cl in Biofield Energy Treated Dichlorophenol Isomers

    Mahendra Kumar Trivedi

    2015-01-01

    2,4-Dichlorophenol (2,4-DCP) and 2,6-dichlorophenol (2,6-DCP) are two isomers of dichlorophenols, have been used as preservative agents for wood, paints, vegetable fibers and as intermediates in the production of pharmaceuticals and dyes. The aim of the study was to evaluate the impact of biofield energy treatment on the isotopic abundance ratios of 2H/1H or 13C/12C, and 18O/16O or 37Cl/35Cl, in dichlorophenol isomers using gas chromatography-mass spectrometry (GC-MS). The 2,4- DCP and 2,6-DC...

  9. Stable isotope labelled mass spectrometry for quantification of the relative abundances for expressed proteins induced by PeaT1

    2010-01-01

    The protein elicitor from the mycelium of Alternaria tenuissima has been isolated.The elicitor triggered resistance to the tobacco mosaic virus in tobacco by inducing relative oxygen species,but without causing hypersensitive necrosis.The elicitor is reported to impart resistance against Verticillium dahliae and to increase yield in cotton,but its mechanism is not yet clear.In this study,the stable isotope labelled mass spectrometry method was used to quantify the relative abundances of protein expression induced by PeaT1 in Arabidopsis.A significant difference in the relative abundances for the expression of different proteins related to metabolism,modification,regulatory,defense,stress and antioxidation was found in Arabidopsis.

  10. Plutonium isotopic abundance measurements on CBNM NRM 271 analyzed with the FRAM and MGA codes

    Friar, R.J.; Sampson, T.E.

    1992-05-01

    We report results of gamma-ray spectroscopy measurements of the isotopic distributions of plutonium in the reference-material set CBNM NRM 271 as analyzed by the FRAM and MGA plutonium isotopic codes. We acquired high-quality spectral data under measurement conditions approximating field-use conditions recommended by the code developers. Bias and precision results from these measurements are presented for both codes. Both codes performed very well for these measurements. These standards have proven to be very useful for testing the Los Alamos FRAM code in the high-burnup region where well-characterized materials have been unavailable at Los Alamos.

  11. Isotopic abundance in the CN coma of comets: Ten years of measurements

    Schulz, R.; Jehin, E.; Manfroid, J.; Hutsemékers, D.; Arpigny, C.; Cochran, A.; Zucconi, J.-M.; Stüwe, J. A.

    2008-11-01

    Over the past 10 years the isotopic ratios of carbon ( 12C/ 13C) and nitrogen ( 14N/ 15N) have been determined for a dozen comets, bright enough to allow obtaining the required measurements from the ground. The ratios were derived from high-resolution spectra of the CN coma measured in the B 2∑ +-X 2∑ + (0, 0) emission band around 387 nm. The observed comets belong to different dynamical classes, including dynamically new as well as long- and short-period comets from the Halley- and Jupiter-family. In some cases the comets could be observed at various heliocentric distances. All values determined for the carbon and nitrogen isotopic ratios were consistent within the error margin irrespective of the type of comet or the heliocentric distance at which it was observed. Our investigations resulted in average ratios of 12C/ 13C=91±21 and nitrogen 14N/ 15N=141±29. Whilst the value for the carbon isotopic ratio is in good agreement with the solar and terrestrial value of 89, the nitrogen isotopic ratio is very different from the telluric value of 272.

  12. Determining the isotopic abundance of a labeled compound by mass spectrometry and how correcting for natural abundance distribution using analogous data from the unlabeled compound leads to a systematic error.

    Schenk, David J; Lockley, William J S; Elmore, Charles S; Hesk, Dave; Roberts, Drew

    2016-04-01

    When the isotopic abundance or specific activity of a labeled compound is determined by mass spectrometry (MS), it is necessary to correct the raw MS data to eliminate ion intensity contributions, which arise from the presence of heavy isotopes at natural abundance (e.g., a typical carbon compound contains ~1.1% (13) C per carbon atom). The most common approach is to employ a correction in which the mass-to-charge distribution of the corresponding unlabeled compound is used to subtract the natural abundance contributions from the raw mass-to-charge distribution pattern of the labeled compound. Following this correction, the residual intensities should be due to the presence of the newly introduced labeled atoms only. However, this will only be the case when the natural abundance mass isotopomer distribution of the unlabeled compound is the same as that of the labeled species. Although this may be a good approximation, it cannot be accurate in all cases. The implications of this approximation for the determination of isotopic abundance and specific activity have been examined in practice. Isotopically mixed stable-atom labeled valine batches were produced, and both these and [(14) C6 ]carbamazepine were analyzed by MS to determine the extent of the error introduced by the approach. Our studies revealed that significant errors are possible for small highly-labeled compounds, such as valine, under some circumstances. In the case with [(14) C6 ]carbamazepine, the errors introduced were minor but could be significant for (14) C-labeled compounds with particular isotopic distributions. This source of systematic error can be minimized, although not eliminated, by the selection of an appropriate isotopic correction pattern or by the use of a program that varies the natural abundance distribution throughout the correction. PMID:26916110

  13. The reduction and oxidation of ceria: A natural abundance triple oxygen isotope perspective

    Hayles, Justin; Bao, Huiming

    2015-06-01

    Ceria (CeO2) is a heavily studied material in catalytic chemistry for use as an oxygen storage medium, oxygen partial pressure regulator, fuel additive, and for the production of syngas, among other applications. Ceria powders are readily reduced and lose structural oxygen when subjected to low pO2 and/or high temperature conditions. Such dis-stoichiometric ceria can then re-oxidize under higher pO2 and/or lower temperature by incorporating new oxygen into the previously formed oxygen site vacancies. Despite extensive studies on ceria, the mechanisms for oxygen adsorption-desorption, dissociation-association, and diffusion of oxygen species on ceria surface and within the crystal structure are not well known. We predict that a large kinetic oxygen isotope effect should accompany the release and incorporation of ceria oxygen. As the first attempt to determine the existence and the degree of the isotope effect, this study focuses on a set of simple room-temperature re-oxidation experiments that are also relevant to a laboratory procedure using ceria to measure the triple oxygen isotope composition of CO2. Triple-oxygen-isotope labeled ceria powders are heated at 700 °C and cooled under vacuum prior to exposure to air. By combining results from independent experimental sets with different initial oxygen isotope labels and using a combined mass-balance and triangulation approach, we have determined the isotope fractionation factors for both high temperature reduction in vacuum (⩽10-4 mbar) and room temperature re-oxidation in air. Results indicate that there is a 1.5‰ ± 0.8‰ increase in the δ18O value of ceria after being heated in vacuum at 700 °C for 1 h. When the vacuum is broken at room temperature, the previously heated ceria incorporates 3-19% of its final structural oxygen from air, with a δ18O value of 2.1-4.1+7.7 ‰ for the incorporated oxygen. The substantial incorporation of oxygen from air supports that oxygen mobility is high in vacancy

  14. Theoretical effect of diffusion on isotopic abundance ratios in rocks and associated fluids

    Senftle, F.E.; Bracken, J.T.

    1955-01-01

    Diffusion is considered as a possible process of isotope fractionation taking place throughout geologic time. Both diffusion in solids and diffusion in liquids are taken as possible mechanisms, the latter being more important. Arguments are presented to show that if significant fractionation takes place within a crystal by outward diffusion under solid-state conditions, enrichment will be evident only in elements of minor concentration. Similar conclusions are inferred for solid-state diffusion across a boundary or for diffusion in liquids. No isotopic enrichment can be expected in relatively large bodies of diffusion transported material. Although the necessary data to confirm these conclusions are scanty, it seems worth while to undertake further work in this direction. ?? 1955.

  15. Evaluation of TASTEX task H: measurement of plutonium isotopic abundances by gamma-ray spectrometry

    Gunnink, R.; Prindle, A.L.; Asakura, Y.; Masui, J.; Ishiguro, N.; Kawasaki, A.; Kataoka, S.

    1981-10-01

    This report describes a computer-based gamma spectrometer system that was developed for measuring isotopic and total plutonium concentrations in nitric acid solutions. The system was installed at the Tokai reprocessing plant where it is undergoing testing and evaluation as part of the Tokai Advanced Safeguards Exercise (TASTEX). Objectives of TASTEX Task H, High-Resolution Gamma Spectrometer for Plutonium Isotopic Analysis, the methods and equipment used, the installation and calibration of the system, and the measurements obtained from several reprocessing campaigns are discussed and described. In general, we find that measurements for gamma spectroscopy agree well with those of mass spectrometry and of other chemical analysis. The system measures both freshly processed plutonium from the product accountability tank and aged plutonium solutions from storage tanks. 14 figures, 15 tables.

  16. Double-comparison method for mass spectrometric determination of hydrogen isotopic abundances

    Hydrogen isotope ratio analysis is subject to interference from H3+, and the uncertainty in the H3+ correction is generally the limiting factor in the precision of hydrogen isotopic analyses. Mathematical modeling indicates that the precision of the analysis can be improved through the use of a double-comparison technique employing a second reference gas. In order to compare the single- and double-comparison techniques, a double-collector isotope ratio mass spectrometer was fitted with a triple viscous leak inlet system. Four H2 samples with deuterium contents between -184 and 193% vs. standard mean ocean water were analyzed by both techniques. The single-comparison analysis had a precision of about 1%. The double-comparison analysis had a precision of 0.04% when combined with electrical H3+ correction. When no H3+ correction was used in the double-comparison measurements, the precision varied as a function of degree of mismatching of major ion currents of the unknown and reference gases and was frequently as poor as .05%

  17. Geographical trends of carbon and sulphur isotope abundances in human kidney stones

    delta13C values and delta34S values in human kidney stones range from -24 to -10 and -10 to +20 per mille, respectively, and depend upon geographical location. Although the distributions overlap, the mean delta13C values in oxalate stones from North America become less negative with decreasing latitude. For Mexico and Hawaii, the distributions appear to be bimodal. Uric acid stones are generally enriched in 13C by up to 7 per mille in comparison to oxalates from the same location, whereas cystine stones tend to span the ranges of both stone types. The geographical trends can be explained by the relative proportions of dietary carbon derived ultimately from plants undergoing various established photosynthetic mechanisms. The differences among the various major stone types may reflect isotope fractionation during biochemical conversions. Exogenic oxalates and uric acid are considered to have little role in precipitating the respective minerals. Whereas, the currently available C isotope data support this contention, more data are desirable, particularly for ingested oxalates. In contrast, S isotope data provide strong evidence that cystine stones are derived from ingested organo-S compounds. In turn, these organo-S compounds were probably derived from sulphate in the hydrosphere at lower levels in the food chain. (author)

  18. Accurate experimental determination of the isotope effects on the triple point temperature of water. I. Dependence on the 2H abundance

    Faghihi, V.; Peruzzi, A.; Aerts-Bijma, A. T.; Jansen, H. G.; Spriensma, J. J.; van Geel, J.; Meijer, H. A. J.

    2015-12-01

    Variation in the isotopic composition of water is one of the major contributors to uncertainty in the realization of the triple point of water (TPW). Although the dependence of the TPW on the isotopic composition of the water has been known for years, there is still a lack of a detailed and accurate experimental determination of the values for the correction constants. This paper is the first of two articles (Part I and Part II) that address quantification of isotope abundance effects on the triple point temperature of water. In this paper, we describe our experimental assessment of the 2H isotope effect. We manufactured five triple point cells with prepared water mixtures with a range of 2H isotopic abundances encompassing widely the natural abundance range, while the 18O and 17O isotopic abundance were kept approximately constant and the 18O  -  17O ratio was close to the Meijer-Li relationship for natural waters. The selected range of 2H isotopic abundances led to cells that realised TPW temperatures between approximately  -140 μK to  +2500 μK with respect to the TPW temperature as realized by VSMOW (Vienna Standard Mean Ocean Water). Our experiment led to determination of the value for the δ2H correction parameter of A2H  =  673 μK / (‰ deviation of δ2H from VSMOW) with a combined uncertainty of 4 μK (k  =  1, or 1σ).

  19. MGA: A gamma-ray spectrum analysis code for determining plutonium isotopic abundances. Volume 3, FORTRAN listing of the GA code

    Gunnink, R

    1991-09-01

    Nondestructive measurements of x-ray and gamma-ray emissions can be used to determine the abundances of various actinides in a sample. Volume 1 of this report describes the methods and algorithms we have developed to determine the relative isotopic abundances of actinides in a sample, by analyzing gamma-ray spectra obtained using germanium detector systems. Volume 2 is a guide to using the MGA (Multiple Group Analysis) computer program we have written to perform plutonium isotopic analyses. This report contains a listing of the FORTRAN instructions of the code.

  20. Authentication of origins of fermentive ethanol in Philippine-made beverages by C,H,O isotope abundances

    This paper demonstrates the expediency of radiocarbon liquid scintillation counting for detection of synthetic ethanol adulteration in Philippine-manufactured wines/alcoholic beverages. The impure wines are distinguished from the pure beverages by radiocarbon assay, taking advantage of the anticipated minor 14Carbon content of synthetic ethyl alcohol in comparison with the natural 14C abundance of the plant-derived, biogenic products. Biogenic samples give 12-15 dpm/g C activities, while synthetic samples exhibits 0-2 dpm/g C activities. The research moreover explores the utility of Deuterium, Oxygen 16 and 13Carbon/ 12Carbon isotope ratio analysis in the authentication of the botanical and geographical origins of beverages. Initial investigations revealed the mean of δ 18O in the Metro Manila area for precipitation, surface waters and ground waters to be -6.09 ± 2.9, -1.59 ± 2.2, and -6.64 ± 0.7 per mil.respectively. δ2H in Metro Manila for precipitation, surface waters and ground waters were -43.8 ± 1.2,-11.9 ± 16.2, -45.0 ± 4.8 per mil respectively. Vital information such as detection of illegal dilution with water, or enrichment using other sugars before and after fermentation, misrepresentation of geographical origin, and adulteration with petroleum-derived ethanol can be generated from the isotopic data. (author)

  1. Effectiveness of leaded petrol phase-out in Tianjin, China based on the aerosol lead concentration and isotope abundance ratio

    The phase-out of leaded petrol has been a measure widely used to reduce atmospheric lead pollution. Since the 1980s, China began to promote unleaded petrol. In order to assess the effectiveness of the measure an isotope fingerprint technique was applied for aerosol samples in the city of Tianjin. After dilute acid leaching, the lead concentration and isotope abundance ratios were determined for 123 samples collected in Tianjin during eight years (1994-2001). The 206Pb / 207Pb ratio was lower in summer, when coal combustion emission was low and vehicle exhaust became more important, indicating that the 206Pb / 207Pb ratio of leaded petrol in Tianjin is lower than that of aerosol samples. The 206Pb / 207Pb ratio gradually increased from 1994 to 2001, a trend that suggests that the contribution from vehicle exhaust was diminishing. Overall, the measurements matched well with national statistical data of leaded and unleaded petrol production. After the nationwide switch to unleaded gasoline, comprehensive control measures are urgently needed to reduce air lead pollution in China, as aerosol lead reduced slightly but remains at a relatively high level

  2. Using natural isotopic abundances to determine the source of nitrous oxide (N2O) emissions

    Mothet, A.; Sebilo, M.; Laverman, A. M.; Vaury, V.; Mariotti, A.

    2012-04-01

    Numerous greenhouse gas studies have focused on carbon dioxide (CO2), whereas nitrous oxide (N2O) also plays a major role in global warming. Indeed, while nitrous oxide is 1000 times less concentrated than CO2 in the atmosphere, it is 300 times more efficient in terms of global warming potential. In addition, its atmospheric concentration increases with 0,3 % per year. According to the literature, nitrous oxide is produced, in soils and sediments, by two major processes: (1) Nitrification, mediated by autotrophic nitrifying bacteria under oxic conditions; (2) Denitrification, mediated by heterotrophic denitrifying bacteria under anoxic conditions. Denitrification induces intensive, localized and instantaneous fluxes. N2O emissions can be easily measured and modeled. In contrast, nitrification induces weak emissions, but spatially and temporally extended. Therefore, this process could represent a large potential of N2O emissions from soils and sediments. The study of isotopomer's isotopic composition of N2O, i.e. the intramolecular distribution or site preference (SP) determined by 15N measurement allows the determination of the origin of N2O emissions (nitrification vs. denitrification). Recent studies on pure cultures have showed that SP associated with nitrification is 35 ‰ while SP associated with denitrification is 0 ‰. The aim of this study was to determine SP associated with denitrification in soils and sediments, taking into account the environmental denitrifying bacterial communities, and under different environmental variables. To this end, flow-through reactors were used to determine denitrification rates at different temperatures and varying substrate (nitrate) concentrations. Site preference was measured for the different experiments. Different experiments of denitrification were realized in sediment flow through reactors under denitrifying conditions (anoxia, presence of organic matter and nitrate). We used acetylene (25°C) to block the enzyme

  3. Evidence of 13C non-covalent isotope effects obtained by quantitative 13C nuclear magnetic resonance spectroscopy at natural abundance during normal phase liquid chromatography.

    Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Rojas, Jose Manuel Moreno; Guillou, Claude; Remaud, Gérald S

    2009-10-16

    Quantitative isotopic (13)C NMR at natural abundance has been used to determine the site-by-site (13)C/(12)C ratios in vanillin and a number of related compounds eluted from silica gel chromatography columns under similar conditions. Head-to-tail isotope fractionation is observed in all compounds at the majority of carbon positions. Furthermore, the site-specific isotope deviations show signatures characteristic of the position and functionality of the substituents present. The observed effects are more complex than would be obtained by simply summing the individual effects. Such detail is hidden when only the global (13)C content is measured by mass spectrometry. In particular, carbon positions within the aromatic ring are found to show site-specific isotope fractionation between the solute and the stationary phase. These interactions, defined as non-covalent isotope effects, can be normal or inverse and vary with the substitution pattern present. PMID:19748628

  4. Rb, Sr and strontium isotopic composition, K/Ar age and large ion lithophile trace element abundances in rocks and glasses from the Wanapitei Lake impact structure

    Shock metamorphosed rocks and shock-produced melt glasses from the Wanapitei Lake impact structure have been examined petrographically and by electron microprobe. Eleven clasts exhibiting varying degrees of shock metamorphism and eight impact-produced glasses have been analyzed for Rb, Sr and Sr isotopic composition. Five clasts and one glass have also been analyzed for large ion lithophile (LIL) trace element abundances including Li, Rb, Sr, and Ba and the REE's. The impact event forming the Wanapitei Lake structure occurred 37 m.y. ago based on K/Ar dating of glass and glassy whole-rock samples. Rb/Sr isotopic dating failed to provide a meaningful whole-rock or internal isochron. The isotopic composition of the glasses can be explained by impact-produced mixing and melting of metasediments. Large ion lithophile trace element abundance patterns confirm the origin of the glasses by total shock melting of metasediments. (author)

  5. Rapid changes in diatom silica surface charge density, silanol abundance, and oxygen isotope values elucidate silica maturation processes in biogenic silica

    Wiedenheft, W.; Dodd, J. P.; Sunderlin, L.

    2014-12-01

    Oxygen isotope values of biogenic silica are increasingly used as proxies of paleoenvironmental conditions. Numerous studies have demonstrated a strong relationship between the diatom silica and the temperature/oxygen isotope value of the formation water; however, some studies have indicated that early diagenesis of biogenic silica may alter the oxygen isotope values by several permil. Quantification of the maturation process has proven difficult since the mechanisms that drive post-mortem changes in the silica oxygen isotope values have not been well characterized. New silica maturation data from marine diatoms, Stephanopyxis turris, cultured in a controlled laboratory experiment demonstrate rapid post-mortem decline in silica reactivity. A decrease in relative abundance of surface silanol groups coincides with a decrease in the surface charge density (excess proton concentration) of freshly harvested frustules. Over a maturation period of 20 days at 85ºC, S. turris samples in a 0.7 M NaCl solution at a pH of 8.0 demonstrate a rapid decrease in the surface charge density from -380 μmoles/g to -16 μmoles/g (Figure 1). FTIR analyses reveal a decrease in the abundance of silanol groups (Si-OH) in the diatom frustules occurs over the same time period. It is important to note that the surface charge density and silanol relative abundance appear to have an asymptotic change through time, indicating that further alteration/reactivity is greatly reduced. Preliminary data indicate that post-mortem increases in the oxygen isotope values of diatom silica observed here and in other studies are coincident with a reduction in the surface charge density and silanol abundance. These experiments demonstrate that rapid post-mortem alteration of biogenic silica is occurring and provide a possible mechanism for alteration of oxygen isotope values in biogenic silica.

  6. Ion-microprobe measurements of Mg, Ca, Ti and Fe isotopic ratios and trace element abundance in hibonite-bearing inclusions in primitive meteorites

    This thesis reports the isotopic abundances of Mg, Ca, and Ti and rare earth element (REE) abundances in 19 hibonite-bearing inclusions from primative meteorites. The isotopic ratios of Fe were measured in one of the samples, Lance HH-1. These measurements were made by means of secondary ion mass spectrometry (CAMECA IMS-3f). The novel hardware and software developments that made this work possible are described in detail. The samples were studied in thin section in order to investigate the relationship between the inclusions and their mineralogical environments. Inclusions from a number of different meteorites, specifically, Mighei, Murray, Murchison, Lance, Efremovka, Vigarano, Qingzhen, Dhajala, and Semarkona, were studied. The isotopes of Ca and Ti show large and correlated abundance anomalies in their most neutron-rich isotopes, 48Ca and 50Ti. The largest anomalies among the samples studied here are in the Murray inclusion MY-F6, with a 4.6% deficit in 48Ca and a 5.2% deficit in 50Ti, and Lance HH-1, with 3.3% and 6.0% deficits in 48Ca and 50Ti respectively. Correlated excesses of 48Ca and 50Ti, up to 2.4% and 1.4% respectively, are found in some other samples studied here. The fact that there is a correlation of isotopic anomalies in two different elements is clear evidence for a nucleosynthetic origin of these effects. Various possibilities for the origin of these isotopic anomalies are discussed and it is shown that a Cosmic Chemical Memory-like model of the incomplete mixing of dust grains from one or several supernovae is sufficient to explain the data. Magnesium isotopes show excesses of 26Mg, attributable to the in-situ decay of 26Al, in 7 of these inclusions

  7. Changes in carbon sources fueling benthic secondary production over depth and time: coupling Chironomidae stable carbon isotopes to larval abundance.

    Frossard, Victor; Verneaux, Valérie; Millet, Laurent; Magny, Michel; Perga, Marie-Elodie

    2015-06-01

    Stable C isotope ratio (δ(13)C) values of chironomid remains (head capsules; HC) were used to infer changes in benthic C sources over the last 150 years for two French sub-Alpine lakes. The HCs were retrieved from a series of sediment cores from different depths. The HC δ(13)C values started to decrease with the onset of eutrophication. The HC δ(13)C temporal patterns varied among depths, which revealed spatial differences in the contribution of methanotrophic bacteria to the benthic secondary production. The estimates of the methane (CH4)-derived C contribution to chironomid biomass ranged from a few percent prior to the 1930s to up to 30 % in recent times. The chironomid fluxes increased concomitantly with changes in HC δ(13)C values before a drastic decrease due to the development of hypoxic conditions. The hypoxia reinforced the implication for CH4-derived C transfer to chironomid production. In Lake Annecy, the HC δ(13)C values were negatively correlated to total organic C (TOC) content in the sediment (Corg), whereas no relationship was found in Lake Bourget. In Lake Bourget, chironomid abundances reached their maximum with TOC contents between 1 and 1.5 % Corg, which could constitute a threshold for change in chironomid abundance and consequently for the integration of CH4-derived C into the lake food webs. Our results indicated that the CH4-derived C contribution to the benthic food webs occurred at different depths in these two large, deep lakes (deep waters and sublittoral zone), and that the trophic transfer of this C was promoted in sublittoral zones where O2 gradients were dynamic. PMID:25630956

  8. Major and trace element abundances, and Sr and Nd isotopic composition of Carbonatites from Amba Dongar, Gujarat, India

    Chandra, Jyoti; Paul, Debajyoti; Viladkar, Shrinivas G.; Sensarma, Sarajit

    2015-04-01

    Despite significant progress during the last decade, the petrogenesis of carbonatites is still highly debated regarding the exact mechanism of carbonatite magma generation (fractional crystallization of carbonated-silicate magmas, liquid immiscibility of carbonated-silicate magmas, partial melting of carbonated mantle peridotite or carbonated lherzolitic mantle) and its evolution. The Amba Dongar carbonatite complex in Chhota Udaipur district, Gujarat is the youngest Indian carbonatite complex, which intruded into the ~ 90 Ma Bagh sandstones and limestone and 68-65 Ma Deccan flood basalts. The emplacement age (40Ar/39Ar age of 65±0.3 Ma; Ray and Pande, 1999) coincides with the age of main pulse of Deccan flood basalts at ca. 65 Ma. We report new geochemical data (major oxide and trace element abundances, and Sr and Nd isotopic ratios) on 23 carbonatite samples from Amba Dongar. The Amba Dongar carbonatite complex consists of carbonatite (sövite, and ankerite), and associated nephelinite, phonolite, and both pre- and post-carbonatite basalts. Detailed minerology of carbonatite include dominant calcite along with pyrochlore, apatite, magnetite, aegirine-augite and accessory phases. Apatite crystals are observed in carbonatite as well as in nephelinite. In sövites, apatite occur in various forms including cumulus, clusters and scattered within and along the boundary of calcite crystals. Two generation of apatite crystals are commonly observed in sövite and nephelinite; textural changes suggest presence of different five pulses of sövitic magma during the emplacement of the sövite ring dike. Bulk major oxides and trace element (including REEs) compositions of carbonatites and associated silicate rocks are determined by WD-XRF and ICP-MS, respectively. Major oxides abundances are consistent with the already available data on the Amba Dongar carbonatite complex. Trace element concentrations for the sövite reveals high concentrations of Sr (929-7476 ppm), Ba (344

  9. Consistency of NMR and mass spectrometry determinations of natural-abundance site-specific carbon isotope ratios. The case of glycerol.

    Zhang, B L; Trierweiler, M; Jouitteau, C; Martin, G J

    1999-07-01

    Quantitative determinations of natural-abundance carbon isotope ratios by nuclear magnetic resonance (SNIF-NMR) have been optimized by appropriate selection of the experimental conditions and by signal analysis based on a dedicated algorithm. To check the consistency of the isotopic values obtained by NMR and mass spectrometry (IRMS) the same glycerol samples have been investigated by both techniques. To have access to site-specific isotope ratios by IRMS, the products have been degraded and transformed into two derivatives, one of which contains carbons 1 and 3 and the other carbon 2 of glycerol. The sensitivity of the isotopic parameters determined by IRMS to fractionation effects possibly occurring in the course of the chemical transformations has been investigated, and the repeatability and reproducibility of both analytical chains have been estimated. The good agreement observed between the two series of isotopic results supports the reliability of the two different approaches. SNIF-NMR is therefore a very attractive tool for routine determination, in a single nondestructive experiment, of the carbon isotope distribution in glycerol, and the method can be applied to other compounds. Using this method, the isotopic distributions have been compared for glycerol samples, obtained from plant or animal oils, extracted from fermented media, or prepared by chemical synthesis. Typical behaviors are characterized. PMID:21662780

  10. Accurate experimental determination of the isotope effects on the triple point temperature of water. II. Combined dependence on the 18O and 17O abundances

    Faghihi, V.; Kozicki, M.; Aerts-Bijma, A. T.; Jansen, H. G.; Spriensma, J. J.; Peruzzi, A.; Meijer, H. A. J.

    2015-12-01

    This paper is the second of two articles on the quantification of isotope effects on the triple point temperature of water. In this second article, we address the combined effects of 18O and 17O isotopes. We manufactured five triple point cells with waters with 18O and 17O abundances exceeding widely the natural abundance range while maintaining their natural 18O/17O relationship. The 2H isotopic abundance was kept close to that of VSMOW (Vienna Standard Mean Ocean Water). These cells realized triple point temperatures ranging between  -220 μK to 1420 μK with respect to the temperature realized by a triple point cell filled with VSMOW. Our experiment allowed us to determine an accurate and reliable value for the newly defined combined 18, 17O correction parameter of AO  =  630 μK with a combined uncertainty of 10 μK. To apply this correction, only the 18O abundance of the TPW needs to be known (and the water needs to be of natural origin). Using the results of our two articles, we recommend a correction equation along with the coefficient values for isotopic compositions differing from that of VSMOW and compare the effect of this new equation on a number of triple point cells from the literature and from our own institute. Using our correction equation, the uncertainty in the isotope correction for triple point cell waters used around the world will be  <1 μK.

  11. Changes in biomarker abundances and sulfur isotopes of pyrite across the Permian Triassic (P/Tr) Schuchert Dal section (East Greenland)

    Fenton, Stephen; Grice, Kliti; Twitchett, Richard J.; Böttcher, Michael E.; Looy, Cindy V.; Nabbefeld, Birgit

    2007-10-01

    In this study, we report on biomarker abundances through parts of the Permian/Triassic boundary (PTB) of Schuchert Dal (East Greenland) that contains rich marine faunal records and excellent terrestrial palynological records. Biomarker abundances and sulfur isotopes are used to correlate the series of events (including changes in element cycling and associated redox conditions of the ocean) surrounding the collapse of the marine and terrestrial ecosystems through this record of a major crisis of life on Earth during a mass extinction episode. The Upper Schuchert Dal Formation contains a low diversity palynological assemblage, ascribed to arborescent cordiaite-conifer-pteridosperm vegetation. Samples from this pre-collapse interval are characterised by high abundances of dibenzofuran (DBF), dibenzothiophene (DBT) and biphenyl. Since these compounds have similar base structures, and show comparable abundance curves, it is plausible that they probably derive from a common source. We propose that phenolic compounds of lignin of the woody plants present during this period could be the source for DBF, DBT and biphenyl. The redox conditions during this period of time also support the formation of DBF and DBT. Just above the extinction interval, there is a dramatic decrease in the abundances of DBF and DBT which occurs at the same time as a sudden change in the stable sulfur isotopic composition ( δ34S) of pyrite, indicating a change in redox conditions from oxic to anoxic/euxinic conditions. δ34S values leading up to the extinction are highly depleted in the heavy sulfur isotope (about - 40‰ vs. VCDT), whilst shortly after the extinction interval much more positive isotope values are observed (about - 25‰). An inferred change in the biogeochemical sulfur cycle is supported by facies evidence from similar neighbouring sections. It is suggested that two processes are operating closely here; 1) Changes in redox conditions and 2) extinction and/or transgression

  12. Determination of plutonium isotopic abundances by gamma-ray spectrometry. Interim report on the status of methods and techniques developed by the Lawrence Livermore Laboratory

    This report presents an overview of methods and techniques developed by the Lawrence Livermore Laboratory for determining plutonium isotopic abundances from gamma-ray spectra that have been measured with germanium detectors. The methodology of fitting the spectral features includes discussions of algorithms for gamma-ray and x-ray peak shape fitting and generation of response spectra profiles characteristic of specific isotopes. Applications of the techniques developed at government, commercial, and Japanese reprocessing plants are described. Current development of the methodology for the nondestructive analysis of samples containing nondescript solid materials is also presented

  13. Estimates of mantle thorium/uranium ratios from Th, U and Pb isotope abundances in basaltic melts

    The relationship between the abundances of Th, U and Pb isotopes in basalt melts and the [Th/U] ratio of their source is assessed. A simple melting model is used to show that whereas the activity ratio (230Th/232Th) in the initial melt before extraction is equal to the bulk source ratio, that in the extracted melt may be higher. The difference depends upon the rate of melting relative to the half-life of 230Th (73 ka). Only when the rate is fast compared to this half life will (230Th/232Th) in the extracted melt provide a correct estimate of [232Th/238U] in the source and therefore of its [Th/U] ratio. This is normally not the case for MORB, and a better estimate of source [Th/U] ratio is derived from [232Th/238U] ratio in the basalt, which does not depend upon the rate of melting. Available data for MORB glasses give a best estimate for their source [Th/U] = 2.58+ 0.06. This value is less than both that of the bulk Earth of 3.9±0.1, and of the source of plume basalts from Iceland and Hawaii, which are 3.3 and 3.2 respectively. These estimates contrast with the [232Th/238U] ratio required to produce the radiogenic {208Pb/206Pb} atomic ratio of MORB over 4.55 Ga. This averages 3.8 and is little different from the average derived from Pb-isotopes in plume basalts. These observations are most easily reconciled if Th, U and Pb are efficiently stripped from the mantle by melting and have a residence time there of ≤ 1 Ga. The [Th/U] ratio of 2.6 for the upper mantle requires melt fractions of ≤ 1% to be involved in transferrring U and Th from this region into the continents. Such melt fractions are present in subduction zones and in the source regions of continental alkali basalts. (author)

  14. The effects of oxides of carbon and nitrogen emissions on the isotope and element abundances in foliage of C3 plants

    The carbon and nitrogen stable isotope abundance of C3 plants mango (Magnifera indica L), molave (Vitex parviflora Juss), talisay (Terminalia catappa L.) leaves harvested from sites with ambient air conditions and sites receiving air pollution contributions from coal-fired power plants were determined and compared. Isotope Ratio Mass Spectroscopy, IRMS was used to determine 13C and 15N in the samples. The elemental composition of the samples was determined using Inductively Coupled Plasma-Atomic Emission Spectrometry, ICP-AES. The 13C of the leaves grown in ambient air were found to fall within the range of -25.0 to -22.0 per mill and a close agreement with the literature values for the natural abundance of 13C in C3 plants (-27.0 to -21.0 per mill). The 13C abundance of plants obtained from sites polluted by coal-fired plants were sporadic from -35 to 24.0 per mille. The 15N abundance in leaves grown under ambient air condition (-1.0 to 2.0 per mille) were way below the 15N abundance of plants from coal-fired plant-polluted regions (16.0 to 17.5 per mille). Elemental exposition indicated no differences in element concentrations in leaves from ambient and polluted sites. Differences exist in the Ca, Mg, K ratios across species and are affected by seasonal variation. (author)

  15. Assessment of Soil Organic Carbon Stability in Agricultural Systems by Using Natural Abundance Signals of Stable Carbon and Nitrogen Isotopes

    Information on the stability and age of soil organic matter (SOM) pools is of vital importance for assessing the impact of soil management and environmental factors on SOM, an important part of the global carbon (C) cycle. The terrestrial soil organic C pool, up to a depth of 1 m, contains about 1500 Pg C (Batjes, 1996). This is about 2.5 times more organic C than the vegetation (650 Pg C) and about twice as much as in the atmosphere (750 Pg C) (Batjes, 1998), but the assessment of the stability and age of SOM using 14C radio carbon technique are expensive. Conen et al. (2008) developed a model to estimate the SOM stability based on the isotopic discrimination of 15N natural abundance by soil micro-organisms and the change in C/N ratio during organic matter decomposition, for steady state, Alpine and permanent grasslands. In the framework of the IAEA funded coordinated research project (CRP) on Soil Quality and Nutrient Management for Sustainable Food Production in Mulch based Cropping Systems in sub-Saharan Africa, research was initiated to use this model in agricultural systems for developing a cost effective and affordable technique for Member States to determine the stability of SOM. As part of this research, soil samples were taken and analysed in four long term field experiments, established on soils with low and high SOM, in Austria and Belgium. The participating institutions are the Austrian Agency for Health and Food Safety (AGES), the University of Natural Resources and Life Sciences in Vienna (BOKU), the University of Leuven (KUL), the Soil Service of Belgium (BDB) and the Centre Wallon de Recherches Agronomiques (CRA-W)

  16. Cumulative fission yields of short-lived isotopes under natural-abundance-boron-carbide-moderated neutron spectrum

    Finn, Erin C.; Metz, Lori A.; Greenwood, Lawrence R.; Pierson, Bruce; Wittman, Richard S.; Friese, Judah I.; Kephart, Rosara F.

    2015-04-09

    The availability of gamma spectroscopy data on samples containing mixed fission products at short times after irradiation is limited. Due to this limitation, data interpretation methods for gamma spectra of mixed fission product samples, where the individual fission products have not been chemically isolated from interferences, are not well-developed. The limitation is particularly pronounced for fast pooled neutron spectra because of the lack of available fast reactors in the United States. Samples containing the actinide isotopes 233, 235, 238U, 237Np, and 239Pu individually were subjected to a 2$ pulse in the Washington State University 1 MW TRIGA reactor. To achieve a fission-energy neutron spectrum, the spectrum was tailored using a natural abundance boron carbide capsule to absorb neutrons in the thermal and epithermal region of the spectrum. Our tailored neutron spectrum is unique to the WSU reactor facility, consisting of a soft fission spectrum that contains some measurable flux in the resonance region. This results in a neutron spectrum at greater than 0.1 keV with an average energy of 70 keV, similar to fast reactor spectra and approaching that of 235U fission. Unique fission product gamma spectra were collected from 4 minutes to 1 week after fission using single-crystal high purity germanium detectors. Cumulative fission product yields measured in the current work generally agree with published fast pooled fission product yield values from ENDF/B-VII, though a bias was noted for 239Pu. The present work contributes to the compilation of energy-resolved fission product yield nuclear data for nuclear forensic purposes.

  17. Carbon-13 kinetic isotope effects in the decarbonylations of lactic acid containing 13C at the natural abundance level

    The 13C kinetic isotope fractionation in the decarbonylation of lactic acid of natural isotopic composition by sulfuric acid has been studied in the temperature range of 20-80 deg C. The 13C(1) isotope separation in the decarbonylation of lactic acid by concentrated sulfuric acid depends strongly on the temperature above 40 deg C. Below this temperature the 13C isotope effect in the decarbonylation of lactic acid by concentrated sulfuric acid is normal similarly as has been found in the decarbonylation of lactic [1-14C] acid. The experimental values of k(12C)/k(13C) ratios of isotopic rate constants for 12C and 13C are close to, but slightly higher than theoretical 13C-kinetic isotope effects calculated (neglecting tunneling) under the asumption that the C(1)-OH bond is broken in the rate-controlling step of the dehydration reaction. Dilution of concentrated sulfuric acid with water up to 1.4 molar (H2O)/(H2SO4) ratio caused the increase of the 13C isotope fractionation from 1.0273 found in concentrated sulfuric acid at 80.5 deg C to 1.0536±0.0008 (at 80.6 deg C). A discussion of the abnormally high temperature dependence of 14C and 13C isotope fractionation in this reaction and the discussion of the problem of relative 14C/13C kinetic isotope effects is given. (author) 18 refs.; 2 tabs

  18. A Computational Framework for High-Throughput Isotopic Natural Abundance Correction of Omics-Level Ultra-High Resolution FT-MS Datasets

    William J. Carreer

    2013-09-01

    Full Text Available New metabolomics applications of ultra-high resolution and accuracy mass spectrometry can provide thousands of detectable isotopologues, with the number of potentially detectable isotopologues increasing exponentially with the number of stable isotopes used in newer isotope tracing methods like stable isotope-resolved metabolomics (SIRM experiments. This huge increase in usable data requires software capable of correcting the large number of isotopologue peaks resulting from SIRM experiments in a timely manner. We describe the design of a new algorithm and software system capable of handling these high volumes of data, while including quality control methods for maintaining data quality. We validate this new algorithm against a previous single isotope correction algorithm in a two-step cross-validation. Next, we demonstrate the algorithm and correct for the effects of natural abundance for both 13C and 15N isotopes on a set of raw isotopologue intensities of UDP-N-acetyl-D-glucosamine derived from a 13C/15N-tracing experiment. Finally, we demonstrate the algorithm on a full omics-level dataset.

  19. Evaluating microbial carbon sources in Athabasca oil sands tailings ponds using natural abundance stable and radiocarbon isotopes

    Ahad, J. M.; Pakdel, H.

    2013-12-01

    Natural abundance stable (δ13C) and radiocarbon (Δ14C) isotopes of phospholipid fatty acids (PLFAs) were used to evaluate the carbon sources utilized by the active microbial populations in surface sediments from Athabasca oil sands tailings ponds. The absence of algal-specific PLFAs at three of the four sites investigated, in conjunction with δ13C signatures for PLFAs that were generally within ~3‰ of that reported for oil sands bitumen (~ -30‰), indicated that the microbial communities growing on petroleum constituents were dominated by aerobic heterotrophs. The Δ14C values of PLFAs ranged from -906 to -586‰ and pointed to a significant uptake of fossil carbon (up to ~90% of microbial carbon derived from petroleum), particularly in PLFAs (e.g., cy17:0 and cy19:0) often associated with petroleum hydrocarbon degrading bacteria. The comparatively higher levels of 14C in other, less specific PLFAs (e.g., 16:0) indicated the preferential uptake of younger organic matter by the general microbial population (~50-80% of microbial carbon derived from petroleum). Since the main carbon pools in tailings sediment were essentially 'radiocarbon dead' (i.e., no detectable 14C), the principal source for this modern carbon is considered to be the Athabasca River, which provides the bulk of the water used in the bitumen extraction process. The preferential uptake of the minor amount of young and presumably more biodegradable material present in systems otherwise dominated by recalcitrant petroleum constituents has important implications for remediation strategies. On the one hand, it implies that mining-related organic contaminants could persist in the environment long after tailings pond reclamation has begun. Alternatively, it may be that the young, labile organic matter provided by the Athabasca River plays an important role in stimulating or supporting the microbial utilization of petroleum carbon in oil sands tailings ponds via co-metabolism or priming processes

  20. Highly sensitive analysis of isotope abundances through negative thermal ionization mass spectrometry and its application to geochemistry and environmental chemistry

    Negative thermal ionization mass spectrometry (N-TIMS) has been recently developed as a precise and accurate method in mass spectrometry to determine isotope ratios of some elements, which cannot be measured by positive thermal ionization mass spectrometry (P-TIMS) easily. In N-TIMS, isotopic compositions of elements, such as halogens, chalcogens, boron and platinum group elements with high ionization potentials, are determined as negative atomic ions M-, oxide ions MOx- (x = 1-4) or fluoride ions MFx- (x = 4). Recent interesting developments in geochemistry is the determinations of rhenium-osmium systematics, redetermination of the relative atomic masses of elements by more precise and more accurate isotope ratio measurements, the determination of isotope variations in geological and cosmic samples and the analysis of trace and ultra-trace amounts of elements in the environment. In this paper, after theory and characteristics of N-TIMS are mentioned, some recent applications of N-TIMS is summarized in the field of geochemistry and environmental chemistry. Among recent topics, (1) application to rhenium-osmium systematics, (2) precise boron isotope analysis and its application to environmental chemistry, and (3) precise iron isotope analysis and its application to biological and medical use are described. Problems involved in N-TIMS are also discussed. (author)

  1. 同位素丰度绝对测量及相对原子质量测定中的不确定度评估%Uncertainty Analysis of Absolute Measurement of Isotopic Abundances and Relative Atomic Mass

    周涛; 王同兴

    2005-01-01

    The sources of uncertainty of relative atomic mass include measurement errors and isotopic fractionation of terrestrial samples. Measurement errors are composed of measurements of atomic masses and isotopic abundances, the later includes uncertainty of correction factor K and isotopic ratios of natural samples. Through differential of seven factors to gain their propagation factors, the uncertainty of correction factors K can be calculated. With the same differential calculation, the uncertainty of relative atomic mass can be obtained.

  2. 我国城市大气颗粒物的铅同位素丰度比%Lead Isotope Abundance Ratios of Urban Atmospheric Aerosols in China

    刘咸德; 李显芳; 李冰

    2004-01-01

    Determined with ICP-MS, new isotope abundance ratio data of lead for Beijing and Changdao aerosols was presented, in comparison with literature data for Chinese urban aerosols. 206Pb/207Pb ratio falls into a range from 1.13 to 1.18 for urban aerosols and less influenced by vehicle exhaust emission after phase-out of leaded petrol in 2000 in China. Major lead pollution sources may probably include coal combustion, oil combustion,re-suspended dust, metallurgical industry and use and production of cement.

  3. Utilization of natural variations in the isotopic abundance of 15N to trace the source of aquifer pollution by nitrates

    The validity of using the natural isotope nitrogen-15 to trace the source of nitrates contained in aquifers is discussed with reference to experimental devices (lysimeters and experimental plots) and for examples chosen from the Paris area. There are a number of sources of nitrates: (1) industrially synthesized nitrates (fertilizers); (2) nitrates produced by oxidation of organic matter associated with human, agricultural or urban activities; (3) nitrates synthesized in the soil by the decay of organic matter. In the examples studied these sources differ in their 15N content: (1) fertilizers have a delta15N close to zero (atmospheric nitrogen); (2) the nitrates originating from organic pollution have high delta15N (above 10-12 per mille) and this 15N enrichment is associated with the volatilization of ammonia during the ammonia stage of mineralization; (3) the isotopic characterization of the nitrates produced by organic matter in the soil is less evident. Citing several examples, the author demonstrates that these three sources are diffentiated isotopically. Consideration of the parameters nitrate concentration/isotopic composition reveals simple mixture curves. In the most complicated cases - where there is association with other isotopic (3H) or chemical parameters - it is possible qualitatively to trace the sources of nitrogen pollution

  4. Deuterium transfer in the bioconversion of glucose to ethanol studied by specific isotope labeling at the natural abundance level

    Martin, G.J.; Zhang, B.L.; Naulet, N.; Martin, M.L.

    1986-08-20

    Site-specific natural isotope fractionation measured by deuterium NMR (SNIF-NMR) was used for investigating the deuterium transfers occurring in the fermentation of sugars into ethanol. In contrast to carbon-13, which is usually assumed to be randomly distributed within the glucose skeleton, very large deviations with respect to a statistical repartition are determined for deuterium. By transforming glucose samples from different origins into acetates and nitrates, the absolute values of the D/H ratios in the nonexchangeable sites were obtained. The hydroxyl sites were considered to contribute to the isotope content of the starting water medium. No direct connection is found between glucose and the methylene site which is only sensitive, with a strong discriminating effect against deuterium, to the isotope content of water. A redistribution coefficient slightly less than unity (0.96 for a concentration of sugar of 100 g L/sup -1/) is found between the isotope ratio of the end and starting water media. The site-specific natural isotope parameters of ethanol constitute a faithful and powerful probe for investigating the physiological biochemical and climatological effects which have governed the photosynthesis of sugars in natural conditions.

  5. Deuterium transfer in the bioconversion of glucose to ethanol studied by specific isotope labeling at the natural abundance level

    Site-specific natural isotope fractionation measured by deuterium NMR (SNIF-NMR) was used for investigating the deuterium transfers occurring in the fermentation of sugars into ethanol. In contrast to carbon-13, which is usually assumed to be randomly distributed within the glucose skeleton, very large deviations with respect to a statistical repartition are determined for deuterium. By transforming glucose samples from different origins into acetates and nitrates, the absolute values of the D/H ratios in the nonexchangeable sites were obtained. The hydroxyl sites were considered to contribute to the isotope content of the starting water medium. No direct connection is found between glucose and the methylene site which is only sensitive, with a strong discriminating effect against deuterium, to the isotope content of water. A redistribution coefficient slightly less than unity (0.96 for a concentration of sugar of 100 g L-1) is found between the isotope ratio of the end and starting water media. The site-specific natural isotope parameters of ethanol constitute a faithful and powerful probe for investigating the physiological biochemical and climatological effects which have governed the photosynthesis of sugars in natural conditions

  6. Standard test method for isotopic abundance analysis of uranium hexafluoride and uranyl nitrate solutions by multi-collector, inductively coupled plasma-mass spectrometry

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    1.1 This test method covers the isotopic abundance analysis of 234U, 235U, 236U and 238U in samples of hydrolysed uranium hexafluoride (UF6) by inductively coupled plasma source, multicollector, mass spectrometry (ICP-MC-MS). The method applies to material with 235U abundance in the range of 0.2 to 6 % mass. This test method is also described in ASTM STP 1344. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  7. Determining the age and history of plutonium using isotope correlations and experimentally determined data on isotopic abundances of plutonium and 241Am

    Linear correlations using a data set of nominally cooled samples of Pu formed in Indian PHWRs using experimentally determined 241Pu/239Pu versus 240Pu/239Pu and 241Am/239Pu versus 240Pu/239Pu isotope ratios have been developed which can be used for determining the age of Pu. By correlating both Pu and Am isotopic information, an understanding of how the material was processed, when chemical separations occurred to remove 241Am as well as the true age of the Pu in sample can be obtained. Two actual samples from a PHWR with unknown origin were analyzed as a part of case study for application of this new methodology. (author)

  8. Determination of 235U isotopic abundance of U samples by a NDA based method to enhance capability of a national safeguards system

    In order to investigate some non-destructive techniques to determine the isotopic abundance of uranium oxide samples for quantitative verification of flow, inventories and balances of material in bulk facilities, the Safeguards Laboratory (LASAL) of the Brazilian Nuclear Energy Commission (CNEN) and the United States Department of Energy (US-DOE), supported by experts from Oak Ridge National Laboratory (ORNL) and Portsmouth Gaseous Diffusion Plant have established a technical cooperation project. Part of this project refers to studies and tests based on gamma and X-ray measurements with a high purity germanium detector (HPGe) with data analysis through a multi-group analysis code - MGAU. Typical accuracies of 1-2% are expected for a single measurement of only a few minutes of counting time for uranium samples in equilibrium with their daughter products, not containing Pu and other radionuclides and with container wall thickness of less than about 10 mm steel. In a laboratory environment, additional investigations are being conducted under a very low background level and using different counting times, geometries and material characteristics in order to meet a performance of 0.5-1% for isotopic abundances over the range from 0.5 to 5% 235U. Previous evaluations demonstrated that this performance would satisfy the safeguards requirements for an effective and efficient verification of inventories and balances of nuclear material in Brazilian bulk facilities by the national inspectorate. (author)

  9. Hf-Nd-Sr isotopes and incompatible element abundances in island arcs: Implications for magma origins and crust-mantle evolution

    We present Hf, Nd and Sr isotopic data and abundances of K, Rb, Cs, Ba, Sr, Hf and REE for 32 samples from seven intra-oceanic island arcs. Samples from the Marianas, Izu, Aleutian and New Britain arcs have tightly grouped 176Hf/177Hfproportional0.28320, 143Nd/144Ndproportional0.51303 and 87Sr/86Srproportional0.7035 close to, but distinct from, mid-ocean ridge basalts (MORB) for 143Nd/144Nd and 87Sr/86Sr. In contrast, samples from the Sunda, Banda and Lesser Antilles arcs are much more variable towards lower 176Hf/177Hf and 143Nd/144Nd, and higher 87Sr/86Sr. Isotopically, island arcs on the whole are closely similar to ocean islands. Some commonly-occurring features of the trace element geochemistry of island arcs are apparent in our data: alkali and alkaline-earth elements, particularly Cs, have high abundance relative to LREE compared to oceanic basalts; negative Ce anomalies occur in six out of seven arcs. However, Hf does not appear underabundant relative to REE. The isotopic data require a continental component in all island arcs, in addition to probable mantle and oceanic crust contributions, even for the arcs with isotope ratios close to MORB. In the absence of continental crust, we can best explain this component by subducted pelagic sediment in the arc magma source region. The involvement of sediments in all arcs implies that there is an inherent recycling of older continent to island arcs, and potentially to new continent, of at least 1%. Conservative calculations show that the upper subducted slab (basalt + sediment) passes beyond the arc magma genesis zone and enters the deep mantle with a minimum of 500-1000 ppm K, and corresponding amounts of other incompatible elements. If this material is not completely homogenized with the mantle and later becomes part of the source of ocean island magmas, then the ocean island-island arc isotopic similarity is a result of their similar mix of source materials-mantle peridotite with trace element signatures from

  10. Mantle in the Manihiki Plateau source with ultra-depleted incompatible element abundances but FOZO-like isotopic signature

    Golowin, R.; Hoernle, K.; Portnyagin, M.; Hauff, F.; Gurenko, A.; Garbe-Schoenberg, C. D.; Werner, R.

    2014-12-01

    The ~120Ma Manihiki Plateau basement consists of high-Ti tholeiitic basalts with EM-I type isotopic signatures, similar to the Singgalo basalts at Ontong Java, and low-Ti tholeiitic basalts with FOZO (Kwaimbaita/Kroenke) to HIMU-type isotopic compositions, similar to late stage volcanism on Hikurangi and Manihiki Plateaus (Hoernle et al. 2010; Timm et al. 2011). The low-Ti basalts have affinities to boninites and have been interpreted to be derived from residual mantle wedge mantle (Ingle et al. 2007). New major, volatile and trace element and radiogenic isotope data have been generated from fresh low-Ti glass samples recovered during R/V Sonne cruises SO193 and SO225. The low-Ti samples have distinctly lower Ti/V ratios compared to lavas from Ontong Java Plateau (Kwaimbaita-Kroenke and Singgalo), but similar to boninitic rocks. Glasses and melt inclusions in olivine have low volatile contents (0.12-0.25 wt% H2O). Olivine chemistry points to derivation from peridotite source. Therefore we interpret the low-Ti lavas to have formed through melting of dry and depleted peridotite at high temperatures, consistent with Timm et al (2011). The low-Ti group is characterized by U-shaped trace element patterns. The glass samples form linear mixing arrays on radiogenic isotope diagrams, pointing to the involvement of two components: 1) a component ultra-depleted in highly incompatible elements (UDC) but with intermediate Pb, Sr and Nd isotopic compositions, being similar to Kwaimbaita/Kroenke lavas from Ontong Java, and 2) an enriched component with HIMU-type incompatible element and isotopic characteristics, similar to late-stage volcanism on Manihiki, Hikurangi and Ontong Java (e.g. Hoernle et al. 2010). The ultra-depleted, FOZO-like mantle component could represent second stage melting of FOZO type mantle or re-melting of young recycled oceanic lithosphere within the plume head. Enrichment with HIMU type melts is required to explain the enrichment in the most incompatible

  11. Double-neutron capture reaction and natural abundance of 183W, 195Pt, and 199Hg isotopes

    The database for neutron cross sections is well developed over the nuclide chart for stable isotopes and not as much for the radioactive species. Double-neutron capture experiments could be productive to supply more data. Time-integrated mean flux of slow neutrons reaches a value of 2.3·1012 cm-2·s-1 at the irradiation port near the active zone of the IBR-2 pulsed reactor of JINR. This is enough to detect the double-neutron capture products by the activation method. A high capture cross section is deduced in the present experiment for intermediate radioactive 182Ta and 194Ir target nuclides. Together with the known one for 198Au, these values may prove an essential role of double-neutron capture process for nucleosynthesis of 183W, 195Pt, and 199Hg isotopes at stellar conditions.

  12. Double-neutron capture reaction and natural abundance of 183W, 195Pt and 199Hg isotopes

    Karamian, S. A.; Aksenov, N. V.; Bozhikov, G. A.

    2016-06-01

    There are much data on neutron cross sections over the chart of nuclides for stable isotopes and not as much for the radioactive ones. Double neutron capture experiments could be fruitful to provide more data. Time-integrated mean flux of slow neutrons reaches the value of 2.3-1012 n/cm2 s at the irradiation port near the active zone of the IBR-2 pulsed reactor of JINR. This is enough to detect the double neutron capture products by the activation method. A high capture cross section is obtained in the present experiment for intermediate radioactive 182Ta and 194Ir target nuclides. Together with the known data for 198Au, these values may prove an essential role of double neutron capture process for nucleosynthesis of 183W, 195Pt and 199Hg isotopes at stellar conditions.

  13. Abundance, stable isotopic composition, and export fluxes of DOC, POC, and DIC from the Lower Mississippi River during 2006-2008

    Cai, Yihua; Guo, Laodong; Wang, Xuri; Aiken, George

    2015-11-01

    Sources, abundance, isotopic compositions, and export fluxes of dissolved inorganic carbon (DIC), dissolved and colloidal organic carbon (DOC and COC), and particulate organic carbon (POC), and their response to hydrologic regimes were examined through monthly sampling from the Lower Mississippi River during 2006-2008. DIC was the most abundant carbon species, followed by POC and DOC. Concentration and δ13C of DIC decreased with increasing river discharge, while those of DOC remained fairly stable. COC comprised 61 ± 3% of the bulk DOC with similar δ13C abundances but higher percentages of hydrophobic organic acids than DOC, suggesting its aromatic and diagenetically younger status. POC showed peak concentrations during medium flooding events and at the rising limb of large flooding events. While δ13C-POC increased, δ15N of particulate nitrogen decreased with increasing discharge. Overall, the differences in δ13C between DOC or DIC and POC show an inverse correlation with river discharge. The higher input of soil organic matter and respired CO2 during wet seasons was likely the main driver for the convergence of δ13C between DIC and DOC or POC, whereas enhanced in situ primary production and respiration during dry seasons might be responsible for their isotopic divergence. Carbon export fluxes from the Mississippi River were estimated to be 13.6 Tg C yr-1 for DIC, 1.88 Tg C yr-1 for DOC, and 2.30 Tg C yr-1 for POC during 2006-2008. The discharge-normalized DIC yield decreased during wet seasons, while those of POC and DOC increased and remained constant, respectively, implying variable responses in carbon export to the increasing discharge.

  14. Determination of site-specific carbon isotope ratios at natural abundance by carbon-13 nuclear magnetic resonance spectroscopy.

    Caer, V; Trierweiler, M; Martin, G J; Martin, M L

    1991-10-15

    Site-specific natural isotope fractionation of hydrogen studied by deuterium NMR (SNIF-NMR) spectroscopy is a powerful source of information on hydrogen pathways occurring in biosyntheses in natural conditions. The potential of the carbon counterpart of this method has been investigated and compared. Three typical molecular species, ethanol, acetic acid, and vanillin, have been considered. Taking into account the requirements of quantitative 13C NMR, appropriate experimental procedures have been defined and the repeatability and reproducibility of the isotope ratio determinations have been checked in different conditions. It is shown that the carbon version of the SNIF-NMR method is capable of detecting small differences in the carbon-13 content of the ethyl fragment of ethanols from different botanical or synthetic origins. These results are in agreement with mass spectrometry determinations of the overall carbon isotope ratios. Deviations with respect to a statistical distribution of 13C have been detected in the case of acetic acid and vanillin. However, since the method is very sensitive to several kinds of systematic error, only a relative significance can be attached at present to the internal parameters directly accessible. Isotope dilution experiments have also been carried out in order to check the consistency of the results. In the present state of experimental accuracy, the 13C NMR method is of more limited potential than 2H SNIF-NMR spectroscopy. However it may provide complementary information. Moreover it is particularly efficient for detecting and quantifying adulterations that aim to mimic the overall carbon-13 content of a natural compound by adding a selectivity enriched species to a less expensive substrate from a different origin. PMID:1759714

  15. 235Uranium isotope abundance certified reference material for gamma spectrometry EC nuclear reference material 171 certification report

    This certification report contains the information necessary for the final certification of EC nuclear reference material 171. It is also intended to inform the user of the reference material concerned on technical/scientific details which are not given in the certificate. The report describes the reference material which consists of sets of U3O8 samples with five different 235U/U abundances, filled in cylindrical aluminium cans. The can bottom serves as window for emitted gamma radiation. The report describes how the 235U/U abundances were characterized, how the other properties relevant for gamma measurements were determined and gives all connected results as well as those from the verification measurements. Appendix A represents the draft certificate. 32 refs

  16. Application of (119)Sn CPMG MAS NMR for Fast Characterization of Sn Sites in Zeolites with Natural (119)Sn Isotope Abundance.

    Kolyagin, Yury G; Yakimov, Alexander V; Tolborg, Søren; Vennestrøm, Peter N R; Ivanova, Irina I

    2016-04-01

    (119)Sn CPMG MAS NMR is demonstrated to be a fast and efficient method for characterization of Sn-sites in Sn-containing zeolites. Tuning of the CPMG echo-train sequence decreases the experimental time by a factor of 5-40 in the case of as-synthesized and hydrated Sn-BEA samples and by 3 orders of magnitude in the case of dehydrated Sn-BEA samples as compared to conventional methods. In the latter case, the reconstruction of the quantitative spectrum without the loss of sensitivity is shown to be possible. The method proposed allows obtaining (119)Sn MAS NMR spectra with improved resolution for Sn-BEA zeolites with natural (119)Sn isotope abundance using conventional MAS NMR equipment. PMID:26978430

  17. An evaluation method of the neutron fluence and spectrum by measuring the change of isotopic abundance ratios of arbitrary pairs of nuclides on heavy irradiation

    An evaluation method of the neutron fluence and mean spectrum with which samples have been irradiated is proposed. The principle is based on measuring the change of the isotopic abundance ratios of arbitrary pairs of nuclides having different neutron absorption cross sections for both thermal and intermediate neutrons. Advantages of the method are as follows, although sensitivity is lower than that of the ordinary activation method in a short irradiation period. i) Any sample can be used irrespective of irradiation history. ii) Nuclides present as impurities in samples can be used as detectors. iii) Neutron fluences and mean spectra with which samples have been heavily irradiated can be measured with reasonable accuracy, thus making it possible to offer the direct information to radiation damage studies. The present study deals with the principle and applicability of the method. (author)

  18. Natural isotopes abundance of 15N and 13C in leaves of some N2-fixing and non N2-fixing trees and shrubs in Syria

    Variability in the natural abundance isotopes of 15N and 13C in leaves of several legume and non-legume plant species grown at different sites of two areas in semi-arid regions of Syria was determined. In the first area (non-saline soil), the 15N values of a number of fixing and non-fixing reference plants ranged from -2.09 to +9.46, depending on plant species and studied site. 15N in a number of legume species including Acacia cyanopylla (-1.73), Acacia farnesiana (-0.55), Prosopis juliflora (-1.64) and Medicago arborea (+1.6) were close to the atmospheric value pointing to a major contribution of N2 fixing in these species; whereas, those of reference plants were highly positive (between +3.6 and +9.46%). In the actinorhizal tree, Elaeagnus angustifolia, the 15N abundance was far lower (-0.46 to -2.1%) strongly suggesting that the plant obtained large proportional contribution from BNF. In contrast, δ15N values in some other legumes and actinorhizal plants were relatively similar to those of reference plants, suggesting that the contribution of fixed N2 is negligible. On the other hand, δ13C% values in leaves of C3 plants were affected by plant species, ranging from a minimum of -28.67% to a maximum of -23%. However, they were the same within each plant species although they were grown at different sites. Moreover, dual stable isotope analysis in leaves of Prosopis juliflora and other non- legumes grown on a salt affected soil (second area) was also conducted. Results showed that salinity did not affect C assimilation in this woody legume since a higher carbon discrimination was obtained indicating that this plant is a salt tolerant species; whereas, N2-fixation was drastically affected (δ15N= +7.03). (Author)

  19. Determination of relative natural isotopic abundance of 2H using NMR spectroscopy and application in food analysis

    The basic relations are defined for determining the content of deuterium in compound CXHP. Hydrogen atoms 1H and 2H are distributed among the individual diastereotopic points in the molecule which is either monodeuterized or non deuterized. The SNIF-NMR parameter is derived from these assumptions. Procedures are presented for preparing samples for NMR experiments. For measuring NMR spectra of 2H the effects are considered of relaxation times and the total time of measurement. Relaxation times of deuterium in small molecules are of the order of 1 second. The possibilities are shown of using 2H NMR spectroscopy for the study of deuterium transfer during chemical and biochemical reactions, for the determination of isotope purity, the determination of the origin of the sample and for the surveillance of technological processes. Examples of the applications are given. (E.S.). 3 figs., 8 tabs., 42 refs

  20. Stable Carbon Isotope Ratios of Individual Pollen Grains as a Proxy for C3- Versus C4-Grass Abundance in Paleorecords: A Validation Study

    Nelson, D. M.; Hu, F.; Pearson, A.

    2007-12-01

    C3 and C4 grasses have distinct influences on major biogeochemical processes and unique responses to important environmental controls. Difficulties in distinguishing between these two functional groups of grasses have hindered paleoecological studies of grass-dominated ecosystems. We recently developed a technique to analyze the stable carbon isotope composition of individual grass-pollen grains using a spooling- wire microcombustion device interfaced with an isotope-ratio mass spectrometer (Nelson et al. 2007). This technique holds promise for improving C3 and C4 grass reconstructions. It requires ~90% fewer grains than typical methods and avoids assumptions associated with mixing models. However, our previous work was based on known C3 and C4 grasses from herbarium specimens and field collections and the technique had not been test using geological samples. To test the ability of this technique to reproduce the abundance of C3 and C4 grasses on the landscape, we measured δ13C values of >1500 individual grains of grass pollen isolated from the surface sediments of 10 North American lakes that span a large gradient of C3 and C4 grass abundance. Results indicate a strong positive correlation (r=0.94) between % C4-grass pollen (derived from classifying δ13C values from single grains as C3 and C4) and the literature-reported abundance of C4 grasses on the landscape. However, the measured % C4-grass pollen shows some deviation from the actual abundance at sites with high proportions of C4 grasses. This is likely caused by uncertainty in the magnitude, composition, and variability of the analytical blank associated with these measurements. Correcting for this deviation using regression analysis improves the estimation of the abundance of C4 grasses on the landscape. Comparison of the % C4-grass pollen with C/N and δ13C measurements of total organic matter in the same lake-sediment samples illustrates the distinct advantage of grass-pollen δ13C as a proxy for

  1. Cyanoacetylene and its /sup 13/C species: Evidence against relative isotope fractionation and improved /sup 12/C//sup 13/C abundance ratios

    Wannier, P.G.; Linke, R.A.

    1978-12-15

    We use the J=9..-->..8 transitions of HCCCN and its /sup 13/C substituted species to obtain several results in Sgr B2 and Ori A. In Sgr B2 we test for relative isotope fractionation among the three carbon sites in HCCCN and find none to a level of +- 5%. We verify that HCCCN has low opacity in both sources and derive /sup 12/C//sup 13/C isotope ratios of 50 (Ori A) and 22 (Sgr B2), an indication of galactic evolution of this important ratio. That the Orion ''plateau'' feature is especially prominent in HCCCN indicates a surprisingly large polyatomic molecule abundance for this energetic source. Our spectra also yield information about other chemical species, including a new transition of NH/sub 2/CN, an improved frequency of U81505, and a new unidentified line U79220. In addition, sensitive upper limits for NH/sub 2/CN, CH/sub 2/CO, and HNO in the Orion ''spike'' source imply that this cloud is relatively deficient in these species.

  2. Volatile abundances and oxygen isotopes in basaltic to dacitic lavas on mid-ocean ridges: The role of assimilation at spreading centers

    Wanless, V.D.; Perfit, M.R.; Ridley, W.I.; Wallace, P.J.; Grimes, Craig B.; Klein, E.M.

    2011-01-01

    Most geochemical variability in MOR basalts is consistent with low- to moderate-pressure fractional crystallization of various mantle-derived parental melts. However, our geochemical data from MOR high-silica glasses, including new volatile and oxygen isotope data, suggest that assimilation of altered crustal material plays a significant role in the petrogenesis of dacites and may be important in the formation of basaltic lavas at MOR in general. MOR high-silica andesites and dacites from diverse areas show remarkably similar major element trends, incompatible trace element enrichments, and isotopic signatures suggesting similar processes control their chemistry. In particular, very high Cl and elevated H2O concentrations and relatively light oxygen isotope ratios (~ 5.8‰ vs. expected values of ~ 6.8‰) in fresh dacite glasses can be explained by contamination of magmas from a component of ocean crust altered by hydrothermal fluids. Crystallization of silicate phases and Fe-oxides causes an increase in δ18O in residual magma, but assimilation of material initially altered at high temperatures results in lower δ18O values. The observed geochemical signatures can be explained by extreme fractional crystallization of a MOR basalt parent combined with partial melting and assimilation (AFC) of amphibole-bearing altered oceanic crust. The MOR dacitic lavas do not appear to be simply the extrusive equivalent of oceanic plagiogranites. The combination of partial melting and assimilation produces a distinct geochemical signature that includes higher incompatible trace element abundances and distinct trace element ratios relative to those observed in plagiogranites.

  3. Earthworm eco-physiological characteristics and quantification of earthworm feeding in vermifiltration system for sewage sludge stabilization using stable isotopic natural abundance

    Li, Xiaowei; Xing, Meiyan, E-mail: lixiaowei419@163.com; Yang, Jian; Dai, Xiaohu

    2014-07-15

    Highlights: • Earthworm growth biomass and activity decreased with the VF depth. • Earthworm gut microbial communities were dominated by Gammaproteobacteria. • δ{sup 15}N and δ{sup 13}C in earthworms decreased with time, and increased with the VF depth. • Effect of earthworm feeding in enhanced VSS reduction was analyzed quantitatively. • Earthworm feeding had low contribution to the enhanced VSS reduction. - Abstract: Previous studies showed that the presence of earthworm improves treatment performance of vermifilter (VF) for sewage sludge stabilization, but earthworm eco-physiological characteristics and effects in VF were not fully investigated. In this study, earthworm population, enzymatic activity, gut microbial community and stable isotopic abundance were investigated in the VF. Results showed that biomass, average weight, number and alkaline phosphatase activity of the earthworms tended to decrease, while protein content and activities of peroxidase and catalase had an increasing tendency as the VF depth. Earthworm gut microbial communities were dominated by Gammaproteobacteria, and the percentages arrived to 76–92% of the microbial species detected. {sup 15}N and {sup 13}C natural abundance of the earthworms decreased with operation time, and increased as the VF depth. Quantitative analysis using δ{sup 15}N showed that earthworm feeding and earthworm–microorganism interaction were responsible for approximately 21% and 79%, respectively, of the enhanced volatile suspended solid reduction due to the presence of earthworm. The finding provides a quantitative insight into how earthworms influence on sewage sludge stabilization in vermifiltration system.

  4. Validation of a high-resolution gamma-ray spectrometry method for determination of 235U isotopic abundance

    The development of advanced computational algorithms for analysis of complex gamma and X-ray spectra has stimulated new investigations involving the use of nondestructive assay (NDA) based methodologies for measuring isotopic composition of nuclear materials. These new techniques provide an improved performance compared to the older analysis methodologies. Although in most cases, destructive assay (DA) techniques are the only way to achieve the desired accuracy, NDA is becoming a more frequently used alternative technique. NDA analysis can be a more simple and desirable solution for several measurement problems whenever its performance meets the imposed requirements. Since 2004 the Nuclear Energy Commission of Brazil (CNEN), in cooperation with the United States Department of Energy (US-DOE), through the Safeguards Laboratory (LASAL) and Oak Ridge National Laboratory (ORNL), respectively, has conducted several joint research activities. One of those projects is aimed to develop and implement a powerful and reliable NDA technique for isotopic and quantitative verification of uranium inventories in Brazilian bulk facilities. In Safeguards applications, desired performance for the applied measurement techniques depends on several factors (i.e. material characteristics, plant throughput, etc). In many cases use of complex DA techniques (i.e. mass spectrometry) requires substantial resources and, when applicable, an NDA option could be a more cost- and time-effective solution. Recently completed first phase of the project included hardware and software upgrades: new high-purity germanium (HPGe) detector, multi-channel analyzer (MCA), and an updated version of the multi-group analysis code - MGAU [1]. Current work includes investigation and validation of the new methodology for measuring powders and pellets enriched from 0.5 to 5% of 235U. The effects of several parameter variations (i.e. counting statistics, geometry, background level, temperature, humidity, etc.) were

  5. Distribution, abundance and carbon isotopic composition of gaseous hydrocarbons in Big Soda Lake, Nevada: an alkaline, meromictic lake

    Distribution and isotopic composition (delta13C) of low molecular weight hydrocarbon gases were studied in Big Soda Lake, an alkaline, meromictic lake with permanently anoxic bottom waters. Methane increased with depth in the anoxic mixolimnion, reached uniform concentrations in the monimolimnion and again increased with depth in monimolimnion bottom sediments. The delta13C[CH4] values in bottom sediment below 1 m sub-bottom depth increased with vertical distance up the core. Monimolimnion delta13C[CH4] values were greater than most delta13C[CH4] values found in the anoxic mixolimnion. No significant concentrations of ethylene or propylene were found in the lake. However ethane, propane, isobutane and n-butane concentrations all increased with water column depth, with respective maximum concentrations of 260, 80, 23 and 22 nM/l encountered between 50 to 60 m depth. Concentrations of ethane, propane and butanes decreased with depth in the bottom sediments. Ratios of CH4/[C2H6 + C3H8] were high in the anoxic mixolimnion, decreased in the monimolimnion and increased with depth in the sediment. We concluded that methane has a biogenic origin in both the sediments and the anoxic water column and that C2-C4 alkanes have biogenic origins in the monimolimnion water and shallow sediments. (author)

  6. Micron-scale coupled carbon isotope and nitrogen abundance variations in diamonds: Evidence for episodic diamond formation beneath the Siberian Craton

    Wiggers de Vries, D. F.; Bulanova, G. P.; De Corte, K.; Pearson, D. G.; Craven, J. A.; Davies, G. R.

    2013-01-01

    The internal structure and growth history of six macro-diamonds from kimberlite pipes in Yakutia (Russia) were investigated with cathodoluminescence imaging and coupled carbon isotope and nitrogen abundance analyses along detailed core to rim traverses. The diamonds are characterised by octahedral zonation with layer-by-layer growth. High spatial resolution SIMS profiles establish that there is no exchange of the carbon isotope composition across growth boundaries at the μm scale and that isotopic variations observed between (sub)zones within the diamonds are primary. The macro-diamonds have δ13C values that vary within 2‰ of -5.3‰ and their nitrogen contents range between 0-1334 at. ppm. There are markedly different nitrogen aggregation states between major growth zones within individual diamonds that demonstrate Yakutian diamonds grew in multiple growth events. Growth intervals were punctuated by stages of dissolution now associated with <10 μm wide zones of nitrogen absent type II diamond. Across these resorption interfaces carbon isotope ratios and nitrogen contents record shifts between 0.5-2.3‰ and up to 407 at. ppm, respectively. Co-variation in δ13C value-nitrogen content suggests that parts of individual diamonds precipitated in a Rayleigh process from either oxidised or reduced fluids/melts, with two single diamonds showing evidence of both fluid types. Modelling the co-variation establishes that nitrogen is a compatible element in diamond relative to its growth medium and that the nitrogen partition coefficient is different between oxidised (3-4.1) and reduced (3) sources. The reduced sources have δ13C values between -7.3‰ and -4.6‰, while the oxidised sources have higher δ13C values between -5.8‰ and -1.8‰ (if grown from carbonatitic media) or between -3.8‰ and +0.2‰ (if grown from CO2-rich media). It is therefore concluded that individual Yakutian diamonds originate from distinct fluids/melts of variable compositions. The

  7. Evaluation of relative isotopic abundance measurements in a quadrupole time-of-flight mass spectrometer for elemental composition determination of natural products in traditional Chinese medicine.

    Wu, Zhi-Jun; Huo, Jia-Li; Chen, Jian-Zhong; Li, Na; Fang, Dong-Mei; Chen, Xiao-Zhen; Zhang, Guo-Lin; Wang, Jian-Hua; Xu, Xiao-Ying

    2013-01-01

    The relative isotopic abundance (RIA) measurement errors of a quadrupole time-of-flight (Q-ToF) instrument incorporating analog-to-digital converter detectors were systemically evaluated by stochastically collecting about 200 data in positive ion mass spectrometry (MS) mode. Errors varied with peak intensities at definite spectral acquisition rates but were very close, even if peak intensities changed sharply at different spectral acquisition rates with the same concentration. Intensity thresholds were systematically defined at 1 Hz of spectral acquisition rates. RIA measurement errors were also evaluated using peak area. It seemed that peak area was better adapted for the high-intensity ions while peak intensity was suited for very low-intensity ions. Several known compounds were selected for RIA measurements for product ions in tandem mass spectropmetry (MS/MS) mode. An extract of a representative traditional Chinese medicinal, Paederia scandens was analyzed with high-performance liquid chromatography-electrospray ionization-QToF-MS/MS. The unique elemental compositions of some compounds could not be identified even with exact masses and MS/MS spectra of measured and reference compounds. RIA errors, especially of (M+2)M(-1), provided vital information for determining the elemental composition. PMID:24261081

  8. Non-constant relative atomic masses due to varying isotopic abundance of polynuclidic elements and their effect on the accuracy of analytical results

    Alterations of actual relative atomic masses occur in natural samples by natural isotope ratio shifts of polynuclidic elements. Therefore, using nuclear properties for gaining a measuring signal, isotopic shifts of certain elements may lead to significant measuring errors

  9. Climate as the dominant control on C3 and C4 plant abundance in the Loess Plateau: Organic carbon isotope evidence from the last glacial-interglacial loess-soil sequences

    2003-01-01

    Abundance of C3 and C4 photosynthesis plants can be inferred relatively from stable carbon isotopic composition of organic matter in soils. The samples from five sequences of the last glacial-interglacial loess-soil in the Chinese Loess Plateau have been measured for organic carbon isotopic ratios (? 13Corg). The organic carbon isotope data show that relative abundance (or biomass) of C4 plants was increased ca. 40% for each sampling site from the last glacial maximum (LGM) to Holocene optimum, and increased southeastward on the Loess Plateau during both periods of LGM and Holocene. Statistic analyses on the steady maximumδ 13Corg values of Holocene soils and modern climatic data from the Loess Plateau and Inner Mongolia indicate that the C4 plant abundance increases with increasing temperature and decreasing precipitation. The C4 plant abundance is related much closer with mean April temperature and precipitation than annual. These results lead us to deduce following conclusions. First, temperature is the major factor for control on variations in C4 plant abundance in the Loess Plateau from the last glacial to interglacial. In the absence of favorable temperature condition, both of low moisture and low atmospheric CO2 concentration are insufficient to drive an expansion of the C4 plants in the plateau. Second, ? 13Corg in the loess-paleosol sequences, as a proxy of the relative abundance of C4 plants in the Loess Plateau, could not be used as an indicator of changes in the summer monsoon intensity unless the temperature had changed without great amplitude. Since all C4 plants are grasses, finally, the increase of the C4 plants supports that forest has not been dominant in the ecosystem on the Loess Plateau during Holocene although precipitation and atmospheric CO2 were largely increased relative to those during LGM.

  10. Nicotine, acetanilide and urea multi-level2H-,13C- and15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry

    Schimmelmann, A.; Albertino, A.; Sauer, P.E.; Qi, H.; Molinie, R.; Mesnard, F.

    2009-01-01

    Accurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the S values of these reference materials should bracket the isotopic range of samples with unknown S values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW-SLAP) and carbonates (NBS 19 and L-SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA-IRMS). At present only L-glutamic acids USGS40 and USGS41 satisfy these requirements for ??13C and ??13N, with the limitation that L-glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i.e. continuous flow) hydrogen reductive gas chromatography-isotope ratio mass-spectrometry (GC-IRMS), (ii) five nicotines for oxidative C, N gas chromatography-combustion-isotope ratio mass-spectrometry (GC-C-IRMS, or GC-IRMS), and (iii) also three acetanilide and three urea reference materials for on-line oxidative EA-IRMS for C and N. Isotopic off-line calibration against international stable isotope measurement standards at Indiana University adhered to the 'principle of identical treatment'. The new reference materials cover the following isotopic ranges: ??2Hnicotine -162 to -45%o, ??13Cnicotine -30.05 to +7.72%, ?? 15Nnicotine -6.03 to +33.62%; ??15N acetanilide +1-18 to +40.57%; ??13Curea -34.13 to +11.71%, ??15Nurea +0.26 to +40.61% (recommended ?? values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as the first organic nitrogen stable isotope reference materials for GC-IRMS that are available with different ??13N

  11. Study of the Role of Terrestrial Processes in the Carbon Cycle Based on Measurements of the Abundance and Isotopic Composition of Atmospheric CO2

    Piper, Stephen C; Keeling, Ralph F

    2012-01-03

    The main objective of this project was to continue research to develop carbon cycle relationships related to the land biosphere based on remote measurements of atmospheric CO2 concentration and its isotopic ratios 13C/12C, 18O/16O, and 14C/12C. The project continued time-series observations of atmospheric carbon dioxide and isotopic composition begun by Charles D. Keeling at remote sites, including Mauna Loa, the South Pole, and eight other sites. Using models of varying complexity, the concentration and isotopic measurements were used to study long-term change in the interhemispheric gradients in CO2 and 13C/12C to assess the magnitude and evolution of the northern terrestrial carbon sink, to study the increase in amplitude of the seasonal cycle of CO2, to use isotopic data to refine constraints on large scale changes in isotopic fractionation which may be related to changes in stomatal conductance, and to motivate improvements in terrestrial carbon cycle models. The original proposal called for a continuation of the new time series of 14C measurements but subsequent descoping to meet budgetary constraints required termination of measurements in 2007.

  12. The 13C-Pocket Structure in AGB Models: Constraints from Zirconium Isotope Abundances in Single Mainstream SiC Grains

    Liu, Nan; Bisterzo, Sara; Davis, Andrew M; Savina, Michael R; Pellin, Michael J

    2014-01-01

    We present postprocess AGB nucleosynthesis models with different $^{13}$C-pocket internal structures to better explain zirconium isotope measurements in mainstream presolar SiC grains by Nicolussi et al. (1997) and Barzyk et al. (2007). We show that higher-than-solar $^{92}$Zr/$^{94}$Zr ratios can be predicted by adopting a $^{13}$C-pocket with a flat $^{13}$C profile, instead of the previous decreasing-with-depth $^{13}$C profile. The improved agreement between grain data for zirconium isotopes and AGB models provides additional support for a recent proposal of a flat $^{13}$C profile based on barium isotopes in mainstream SiC grains by Liu et al. (2014).

  13. Principles of stable isotope distribution

    Criss, Robert E

    1999-01-01

    1. Abundance and Measurement of Stable Isotopes 1.1. Discovery of Isotopes 1.2. Nuclide Types, Abundances, and Atomic Weights 1.3. Properties and Fractionation of Isotopic Molecules 1.4. Material Balance Relationships 1.5. Mass Spectrometers 1.6. Notation and Standards 1.7. Summary 1.8. Problems References 2. Isotopic Exchange and Equilibrium Fractionation 2.1. Isotopic Exchange Reactions 2.2. Basic Equations 2.3. Molecular Models 2.4. Theory of Isotopic Fractionation 2.5. Temperature Dependence of Isotopic Fractionation Factors 2.6. Rule of the Mean 2.7. Isotopic Thermometers

  14. Assessment of marine-derived nutrients in the Copper River Delta, Alaska, using natural abundance of the stable isotopes of nitrogen, sulfur, and carbon

    Kline, Thomas C.; Woody, Carol Ann; Bishop, Mary Anne; Powers, Sean P.; Knudsen, E. Eric

    2007-01-01

    We performed nitrogen, sulfur, and carbon stable isotope analysis (SIA) on maturing and juvenile anadromous sockeye and coho salmon, and periphyton in two Copper River delta watersheds of Alaska to trace salmonderived nutrients during 2003–2004. Maturing salmon were isotopically enriched relative to alternate freshwater N, S, and C sources as expected, with differences consistent with species trophic level differences, and minor system, sex, and year-to-year differences, enabling use of SIA to trace these salmon-derived nutrients. Periphyton naturally colonized, incubated, and collected using Wildco Periphtyon Samplers in and near spawning sites was 34S- and 15N-enriched, as expected, and at all freshwater sites was 13C-depleted. At nonspawning and coho-only sites, periphyton 34S and 15N was generally low. However, 34S was low enough at some sites to be suggestive of sulfate reduction, complicating the use of S isotopes. Juvenile salmon SIA ranged in values consistent with using production derived from re-mineralization as well as direct utilization, but only by a minority fraction of coho salmon. Dependency on salmon-derived nutrients ranged from relatively high to relatively low, suggesting a space-limited system. No one particular isotope was found to be superior for determining the relative importance of salmon-derived nutrients.

  15. Carbon-13 isotopic abundance and concentration of atmospheric methane for background air in the Southern and Northern Hemispheres from 1978 to 1989

    Atmospheric methane (CH4) may become an increasingly important contributor to global warming in future years. Its atmospheric concentration has risen, doubling over the past several hundred years, and additional methane is thought to have a much greater effect on climate, on a per molecule basis, than additional C02 at present day concentrations (Shine et al. 1990). The causes of the increase of atmospheric CH4 have been difficult to ascertain because of a lack of quantitative knowledge of the fluxes (i.e., net emissions) from the numerous anthropogenic and natural sources. The goal of CH4 isotopic studies is to provide a constraint (and so reduce the uncertainties) in estimating the relative fluxes from the various isotopically distinct sources, whose combined fluxes must result in the measured atmospheric isotopic composition, after the fractionating effect of the atmospheric removal process is considered. In addition, knowledge of the spatial and temporal changes in the isotopic composition of atmospheric CH4, along with estimates of the fluxes from some of the major sources, makes it possible to calculate growth rates for sources whose temporal emissions trends would be difficult to measure directly

  16. Determining the Local Abundance of Martian Methane and its 13-C/l2-C and D/H Isotopic Ratios for Comparison with Related Gas and Soil Analysis on the 2011 Mars Science Laboratory (MSL) Mission

    Webster, Christopher R.; Mahaffy, Paul R.

    2011-01-01

    Understanding the origin of Martian methane will require numerous complementary measurements from both in situ and remote sensing investigations and laboratory work to correlate planetary surface geophysics with atmospheric dynamics and chemistry. Three instruments (Quadrupole Mass Spectrometer (QMS), Gas Chromatograph (GC) and Tunable Laser Spectrometer (TLS)) with sophisticated sample handling and processing capability make up the Sample Analysis at Mars (SAM) analytical chemistry suite on NASA s 2011 Mars Science Laboratory (MSL) Mission. Leveraging off the SAM sample and gas processing capability that includes methane enrichment, TLS has unprecedented sensitivity for measuring absolute methane (parts-per-trillion), water, and carbon dioxide abundances in both the Martian atmosphere and evolved from heated soil samples. In concert with a wide variety of associated trace gases (e.g. SO2, H2S, NH3, higher hydrocarbons, organics, etc.) and other isotope ratios measured by SAM, TLS will focus on determining the absolute abundances of methane, water and carbon dioxide, and their isotope ratios: 13C/12C and D/H in methane; 13C/12C and 18O/17O/16O in carbon dioxide; and 18O/17O/16O and D/H in water. Measurements near the MSL landing site will be correlated with satellite (Mars Express, Mars 2016) and ground-based observations.

  17. Method for the Purification of Inorganic Phosphate in Soil- and Sediment Samples Prior to Analysis of the δ18O Isotopic Abundance in Phosphate

    The ratio of stable oxygen isotopes in phosphate has been used successfully to study the biological cycling of phosphorus in seawater and marine sediments, and now this approach is being applied to study phosphorus cycling in agricultural soils. As an important major element, phosphorus can limit agricultural production and on the other hand excess of phosphorus can lead to water pollution. A better understanding of phosphorus cycling is essential to improve agricultural and environmental management

  18. Developing Model Constraints on Northern Extra-Tropical Carbon Cycling Based on measurements of the Abundance and Isotopic Composition of Atmospheric CO2

    Keeling, Ralph [UCSD-SIO

    2014-12-12

    The objective of this project was to perform CO2 data syntheses and modeling activities to address two central questions: 1) how much has the seasonal cycle in atmospheric CO2 at northern high latitudes changed since the 1960s, and 2) how well do prognostic biospheric models represent these changes. This project also supported the continuation of the Scripps time series of CO2 isotopes and concentration at ten baseline stations distributed globally.

  19. Carbon isotopes: variations of their natural abundance. Application to correction of radiocarbon dates, to the study of plant metabolism and to paleoclimate

    The radiocarbon activity of contemporaneous samples shows: i) variations in the specific activity of the atmospheric C14, which varies with time and locality. ii) variations due to isotope discrimination, or fractionation, of the carbon isotope ratio during the fixation of carbon by organic or inorganic matter. The variation in the atmospheric concentration of carbon 14 as observed in tree rings are synchronous and of the same amplitude for both hemispheres (southern and northern). A curve for correction of radiocarbon dates of the southern hemisphere is given for the last 500 years. The activity of atmospheric radiocarbon as measured in tree rings varies with latitude, showing a difference of (4.5+-1) per mille between the northern and southern hemispheres, the latter having lower concentration of radiocarbon, equivalent to an age difference of about 35 years. This variation can be explained by a larger exchange of carbon 14 between the atmosphere and the sea in the southern hemisphere to a larger free ocean surface (40%) and a higher agitation by winds. The main differences of the isotope fractionation by different types of plants are correlated to their photosynthetic pathways and thus to the enzyme which effects the primary fixation of carbon. The delta C13 values can be used as basis of a paleoclimate indicator

  20. Origin of the eclogitic clasts with graphite-bearing and graphite-free lithologies in the Northwest Africa 801 (CR2) chondrite: Possible origin from a Moon-sized planetary body inferred from chemistry, oxygen isotopes and REE abundances

    Hiyagon, H.; Sugiura, N.; Kita, N. T.; Kimura, M.; Morishita, Y.; Takehana, Y.

    2016-08-01

    In order to clarify the origin of the eclogitic clasts found in the NWA801 (CR2) chondrite (Kimura et al., 2013), especially, that of the high pressure and temperature (P-T) condition (∼3 GPa and ∼1000 °C), we conducted ion microprobe analyses of oxygen isotopes and rare earth element (REE) abundances in the clasts. Oxygen isotopic compositions of the graphite-bearing lithology (GBL) and graphite-free lithology (GFL) show a slope ∼0.6 correlation slightly below the CR-CH-CB chondrites field in the O three-isotope-diagram, with a large variation for the former and almost homogeneous composition for the latter. The average REE abundances of the two lithologies show almost unfractionated patterns. Based on these newly obtained data, as well as mineralogical observations, bulk chemistry, and considerations about diffusion timescales for various elements, we discuss in detail the formation history of the clasts. Consistency of the geothermobarometers used by Kimura et al. (2013), suggesting equilibration of various elements among different mineral pairs, provides a strong constraint for the duration of the high P-T condition. We suggest that the high P-T condition lasted 102-103 years. This clearly precludes a shock high pressure (HP) model, and hence, strongly supports a static HP model. A static HP model requires a Moon-sized planetary body of ∼1500 km in radius. Furthermore, it implies two successive violent collisions, first at the formation of the large planetary body, when the clasts were placed its deep interior, and second, at the disruption of the large planetary body, when the clasts were expelled out of the parent body and later on transported to the accretion region of the CR chondrites. We also discuss possible origin of O isotopic variations in GBL, and presence/absence of graphite in GBL/GFL, respectively, in relation to smelting possibly occurred during the igneous process(es) which formed the two lithologies. Finally we present a possible

  1. Estimation of the contribution of soil carbon to paddy rice and soil to rice carbon transfer factor using natural abundances of stable carbon isotopes

    To obtain the soil-to-rice transfer factor (TF) of carbon-14 (14C), TF of stable carbon was estimated by measuring stable carbon isotope ratios (13C/12C) and total C concentrations in rice grain and associated soil samples collected throughout Japan. Carbon isotope ratios were reported in terms of a δ13C value. By comparing δ13C values for brown rice, white rice and bran, we concluded that white rice was the most suitable part to be used for this estimation because it reflects products from photosynthesis. The δ13C values for white rice and soil showed a weak correlation which may indicate a potential carbon supply from soil to rice. Thus we took a statistical approach to estimate the percent of soil-origin carbon in rice plants. We found that a maximum 1.6% of total carbon in rice plants was from soil under the reasonable assumptions that the carbon fractionation by paddy rice was -19 per mille and δ13C of atmospheric CO2 was -8 per mille. Maximum TF value ranged from 0.05 to 0.5 for stable carbon and the value would also be applicable for 14C because the carbon fractionation effect for 14C would be negligible in carbon transfer. (author)

  2. Measurement of 13CO2/12CO2 abundance by nondispersive infrared heterodyne ratiometry as an alternative to gas isotope ratio mass spectrometry

    The authors report the performance of a prototype nondispersive infrared heterodyne ratiometer in the analysis of seven reference gas samples containing 3.0% CO2 in air, and isotopic enrichments from -85 to +329 δ per thousand vs. PDB as measured by gas isotope ratio mass spectrometry. The instrument response in volts-1 (V-1) varied from -0.51 to 1.22 over the range of -85 to +329 per thousand. A mean instrument response with a 0.0015 standard deviation (0.375 per thousand) required 110 s of signal averaging at a 1-s sampling rate. The calibration curve of instrument response vs. δ per thousand was linear over the entire range and had a slope of 0.003 89 +/- 0.000 03 (SD), an intercept of -0.168 +/- 0.005, and a standard error of 0.009. With this curve, 45 s of data acquisition at a mean instrument response of -0.280 V-1 attained a standard deviation of +/- 1.3 per thousand at -28.7 per thousand. Nondispersive infrared heterodyne ratiometry can analyze the 13C content of respiratory gas samples with acceptable accuracy and sensitivity for clinical studies

  3. Abundance Anomaly of the $^{13}$C Isotopic Species of c-C$_3$H$_2$ in the Low-Mass Star Formation Region L1527

    Yoshida, Kento; Tokudome, Tomoya; Lopez-Sepulcre, Ana; Watanabe, Yoshimasa; Takano, Shuro; Lefloch, Bertrand; Ceccarelli, Cecilia; Bachiller, Rafael; Caux, Emmanuel; Vastel, Charlotte; Yamamoto, Satoshi

    2015-01-01

    The rotational spectral lines of c-C$_3$H$_2$ and two kinds of the $^{13}$C isotopic species, c-$^{13}$CCCH$_2$ ($C_{2v}$ symmetry) and c-CC$^{13}$CH$_2$ ($C_s$ symmetry) have been observed in the 1-3 mm band toward the low-mass star-forming region L1527. We have detected 7, 3, and 6 lines of c-C$_3$H$_2$, c-$^{13}$CCCH$_2$ , and c-CC$^{13}$CH$_2$, respectively, with the Nobeyama 45 m telescope, and 34, 6, and 13 lines, respectively, with the IRAM 30 m telescope, where 7, 2, and 2 transitions, respectively, are observed with the both telescopes. With these data, we have evaluated the column densities of the normal and $^{13}$C isotopic species. The [c-C$_3$H$_2$]/[c-$^{13}$CCCH$_2$] ratio is determined to be $310\\pm80$, while the [c-C$_3$H$_2$]/[c-CC$^{13}$CH$_2$] ratio is determined to be $61\\pm11$. The [c-C$_3$H$_2$]/[c-$^{13}$CCCH$_2$] and [c-C$_3$H$_2$]/[c-CC$^{13}$CH$_2$] ratios expected from the elemental $^{12}$C/$^{13}$C ratio are 60-70 and 30-35, respectively, where the latter takes into account the ...

  4. Application of Natural Isotopic Abundance ¹H-¹³C- and ¹H-¹⁵N-Correlated Two-Dimensional NMR for Evaluation of the Structure of Protein Therapeutics.

    Arbogast, Luke W; Brinson, Robert G; Marino, John P

    2016-01-01

    Methods for characterizing the higher-order structure of protein therapeutics are in great demand for establishing consistency in drug manufacturing, for detecting drug product variations resulting from modifications in the manufacturing process, and for comparing a biosimilar to an innovator reference product. In principle, solution NMR can provide a robust approach for characterization of the conformation(s) of protein therapeutics in formulation at atomic resolution. However, molecular weight limitations and the perceived need for stable isotope labeling have to date limited its practical applications in the biopharmaceutical industry. Advances in NMR magnet and console technologies, cryogenically cooled probes, and new rapid acquisition methodologies, particularly selective optimized flip-angle short transient pulse schemes and nonuniform sampling, have greatly ameliorated these limitations. Here, we describe experimental methods for the collection and analysis of 2D (1)H(N)-(15)N-amide- and (1)H-(13)C-methyl-correlated spectra applied to protein drug products at natural isotopic abundance, including representatives from the rapidly growing class of monoclonal antibody (mAb) therapeutics. Practical aspects of experimental setup and data acquisition for both standard and rapid acquisition NMR techniques are described. Furthermore, strategies for the statistical comparison of 2D (1)H(N)-(15)N-amide- and (1)H-(13)C-methyl-correlated spectra are detailed. PMID:26791974

  5. Recent advances in the analysis of the site-specific isotopic fractionation of metabolites such as fatty acids using anisotropic natural-abundance 2H NMR spectroscopy: application to conjugated linolenic methyl esters.

    Lesot, Philippe; Serhan, Zeinab; Billault, Isabelle

    2011-01-01

    The full elucidation of the enzymatic mechanisms leading to polyunsaturated ω-3 to ω-5 fatty acids (PUFAs) occurring in plants or microorganisms by analyzing their site-specific isotopic fractionation profiles is a challenging task. Isotropic SNIF-NMR® method is an historical, powerful tool for the determination of ((2)H/(1)H) ratios. However, the absence of accessible isotopic data on the enantiotopic hydrogen sites (CH(2) groups) prevents the study of the enzymatic reaction stereoselectivity. Natural-abundance deuterium (NAD) 2D NMR experiment using chiral liquid crystals (CLC) as solvent is a new tool in this field, overcoming this limitation. In this work, we have explored various possibilities for optimizing the enantio-discrimination properties of CLC by changing the nature of the polypeptide and/or increasing the polarity of the organic co-solvents. We report also the first applications of TMU as co-solvent for preparing enantio-discriminating, homogenous polypeptide mesophases. The various experimental NAD NMR results recorded at an optimal sample temperature are discussed and compared in terms of number of discriminated (2)H sites and magnitude of spectral separation for different PUFAs such as the linoleic and linolenic acids. The comparison of all NMR results shows that optimal results are obtained when CLC mixtures made of poly-γ-benzyl-L-glutamate (PBLG) and high polarity co-solvents are used. As new challenging examples of applications, we report the preliminary analytical results obtained from two ω-5 conjugated linolenic acids: the α-eleostearic acid (9Z, 11E, 13E) and the punicic acid (9Z, 11E, 13Z). NMR data are discussed in terms of molecular orientational ordering parameters and isotopic distribution. PMID:21107978

  6. Relationship of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran levels to stable-nitrogen isotope abundance in marine birds and mammals in coastal California

    Jarman, W.M. [Univ. of California, Santa Cruz, CA (United States). Inst. of Marine Sciences; Sydeman, W.J. [International Biological Research, Stinson Beach, CA (United States). Point Reyes Bird Observatory; Hobson, K.A. [Canadian Wildlife Service, Saskatoon, Saskatchewan (Canada). Prairie and Northern Wildlife Research Centre; Bergqvist, P.A. [Univ. of Umeaa (Sweden). Inst. of Environmental Chemistry

    1997-05-01

    Levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in common murre (Uria aalge), Brandt`s cormorant (Phalacrocorax penicillatus), rhinoceros auklet (Cerorhinca monocerata), and pigeon guillemot (Cepphus columba) eggs, and Steller sea lion (Eumetopias jubatus) blubber collected from the Gulf of the Farallones National Marine Sanctuary in 1993. In addition, the samples were analyzed for stable-nitrogen isotopes ({delta}{sup 15}N). Of the PCDDs and PCDFs, the 2,3,7,8-TCDD (TCDD) and 2,3,7,8-TCDF (TCDF) congeners were the most prominent in the birds. The levels of TCDD in the eggs ranged from 0.2 to 6.6 ng/wet kg in the pigeon guillemot and Brandt`s cormorant, respectively. The TCDF ranged from 0.30 to 2.25 ng/kg in the pigeon guillemot and Brandt`s cormorant eggs, respectively. Other prominent PCDD and PCDF congeners detected in all bird species were 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, 1,2,3,7,8-PeCDD and 1,2,3,4,6,7,8-HpCDD. In the Steller sea lion the most prominent congeners were 1,2,3,7,8-PeCDD at 3.2 ng/kg, 2,3,7,8-TCDD at 2.9 ng/kg, OCDF at 2.2 ng/kg, 1,2,3,6,7,8-HxCDD at 1.92 ng/kg, and 1,2,3,4,7,8-HxCDF at 1.3 ng/kg. Stable-nitrogen values ranged from 16.9% in the pigeon guillemot and rhinoceros auklet to 19.8% in the Steller sea lion.

  7. 238U series isotopes and 232Th in carbonates and black shales from the Lesser Himalaya: implications to dissolved uranium abundances in Ganga-Indus source waters

    238U and 232Th concentrations and the extent of 238U-234U-230Th radioactive equilibrium have been measured in a suite of Precambrian carbonates and black shales from the Lesser Himalaya. These measurements were made to determine their abundances in these deposits, their contributions to dissolved uranium budget of the headwaters of the Ganga and the Indus in the Himalaya and to assess the impact of weathering on 238U-234U-230Th radioactive equilibrium in them. 238U concentrations in Precambrian carbonates range from 0.06 to 2.07 μg g-1. The 'mean' U/Ca in these carbonates is 2.9 ng U mg-1 Ca. This ratio, coupled with the assumption that all Ca in the Ganga-Indus headwaters is of carbonate origin and that U and Ca behave conservatively in rivers after their release from carbonates, provides an upper limit on the U contribution from these carbonates, to be a few percent of dissolved uranium in rivers. There are, however, a few streams with low uranium concentrations, for which the carbonate contribution could be much higher. These results suggest that Precambrian carbonates make only minor contributions to the uranium budget of the Ganga-Indus headwaters in the Himalaya on a basin wide scale, however, they could be important for particular streams. Similar estimates of silicate contribution to uranium budget of these rivers using U/Na in silicates and Na* (Na corrected for cyclic and halite contributions) in river waters show that silicates can contribute significantly (∼40% on average) to their U balance. If, however, much of the uranium in these silicates is associated with weathering resistant minerals, then the estimated silicate uranium component would be upper limits. Uranium concentration in black shales averages about 37 μg g-1. Based on this concentration, supply of U from at least ∼50 mg of black shales per liter of river water is needed to balance the average river water U concentration, 1.7 μg L-1 in the Ganga-Indus headwaters. Data on the

  8. Natural isotopes abundance of sup 1 sup 5 N and sup 1 sup 3 C in leaves of some N sub 2 -fixing and non N sub 2 -fixing trees and shrubs in Syria

    Varability in the natural abundance isotopes of sup 1 sup 5 N and sup 1 sup 3 C in leaves of several legume and non-legume plant species grown at different sites of two areas in semi-arid regions of Syria was determined. In the first area (non-saline soil), the sup 1 sup 5 N values of a number of fixing and non-fixing reference plants ranged from -2.09 to +9.46, depending on plant species and studied site. sup 1 sup 5 N in a number of legume species including Acacia cyanopylla (-1.73), Acacia farnesiana (-0.55), Prosopis juliflora (-1.64) and Medicago arborea (+1.6) were close to the atmospheric value pointing to a major contribution of N sub 2 fixing in these species; whereas, those of reference plants were highly positive (between +3.6 and +9.46%). In the actinorhizal tree, Elaeagnus angustifolia, the sup 1 sup 5 N abundance was far lower (-0.46 to -2.1%) strongly suggesting that the plant obtained large proportional contribution from BNF. In contrast, delta sup 1 sup 5 N values in some other legumes and actinorhizal plants were relatively similar to those of reference plants, suggesting that the contribution of fixed N sub 2 is negligible. On the other hand, delta sup 1 sup 3 C% values in leaves of C3 plants were affected by plant species, ranging from a minimum of -28.67% to a maximum of -23%. However, they were the same within each plant species although they were grown at different sites. Moreover, dual stable isotope analysis in leaves of Prosopis juliflora and other non- legumes grown on a salt affected soil (second area) was also conducted. Results showed that salinity did not affect C assimilation in this woody legume since a higher carbon discrimination was obtained indicating that this plant is a salt tolerant species; whereas, N2-fixation was drastically affected (delta sup 1 sup 5 N= +7.03). (Author)

  9. Isotope Spectroscopy

    Caffau, E; Bonifacio, P; Ludwig, H -G; Monaco, L; Curto, G Lo; Kamp, I

    2013-01-01

    The measurement of isotopic ratios provides a privileged insight both into nucleosynthesis and into the mechanisms operating in stellar envelopes, such as gravitational settling. In this article, we give a few examples of how isotopic ratios can be determined from high-resolution, high-quality stellar spectra. We consider examples of the lightest elements, H and He, for which the isotopic shifts are very large and easily measurable, and examples of heavier elements for which the determination of isotopic ratios is more difficult. The presence of 6Li in the stellar atmospheres causes a subtle extra depression in the red wing of the 7Li 670.7 nm doublet which can only be detected in spectra of the highest quality. But even with the best spectra, the derived $^6$Li abundance can only be as good as the synthetic spectra used for their interpretation. It is now known that 3D non-LTE modelling of the lithium spectral line profiles is necessary to account properly for the intrinsic line asymmetry, which is produced ...

  10. Mass independent isotope separations

    Mass independent separations between isotopes of an element were first observed by Clayton on 17 O and 18 O from the Allende meteorite and attributed then to nucleosynthesis. Anomalous ratios of isotope abundance known at that time were due to nuclear processes. Later, atmospheric ozone and stratospheric CO2 were shown to exhibit mass independent isotope composition of oxygen. Several formation mechanisms of these 'anomalous' molecules have been proposed, none being completely satisfactory. In the laboratory, these mass independent chemical separation effects were eventually reproduced. Anomalous separations were also obtained between isotopes of uranium, and even of light elements such as magnesium. These were first connected with irregularities in atomic nucleus volumes. Such effects are not recorded on natural terrestrial samples. Two main reasons prevent such observations from having been made. Firstly, laboratories investigating isotope compositions of elements, publish almost exclusively deltas of one isotope only. But, to look for possible anomalies, one needs to compare each isotope abundance in a sample similar to that in the standard used as origin of deltas. An example of such calculation will be given. Secondly, deltas of isotopes published by different laboratories are usually not comparable to better than a few per mil. The reason is that, to calculate deltas, most laboratories use working standards whose absolute values may not be exactly established as they are not crucial to their work. Several per mil differences will be shown to be implied between the 'absolute' isotope abundance of 13 C of standards, reputedly the same, used by different laboratories. Laboratories making surveys of natural samples should be encouraged, e.g. by IUPAC, to cover every isotope of multiple isotope elements, and to make, at not infrequent intervals, a close comparison of their working standards with internationally distributed ones. (author)

  11. Isotopic investigation of an Australian island environment

    Collagen has been extracted from fossil bones of mega-fauna herbivores from Kangaroo Island, South Australia (Australia). Carbon and nitrogen stable isotope analyses of collagen have provided an insight into the palaeo-ecology of these late Pleistocene herbivores. In comparison with continental fossil localities in South Australia, the island herbivores have elevated nitrogen isotopic abundances. Carbon isotopic abundances suggest that browsing species had a mixed diet of grasses and leaves on the island, in contrast to the specimens from mainland Australia. Possible causes regarding elevated nitrogen isotope abundances and dietary shifts in this palaeo-ecology are discussed. (authors). 24 refs., 2 figs., 1 tab

  12. Study of the primordial lithium abundance

    2011-01-01

    Lithium isotopes have attracted an intense interest because the abundance of both 6Li and 6Li from big bang nucleosynthesis (BBN) is one of the puzzles in nuclear astrophysics. Many investigations of both astrophysical observation and nucleosynthesis calculation have been carried out to solve the puzzle, but it is not solved yet. Several nuclear reactions involving lithium have been indirectly measured at China Institute of Atomic Energy, Beijing. The Standard BBN (SBBN) network calculations are then performed to investigate the primordial Lithium abundance. The result shows that these nuclear reactions have minimal effect on the SBBN abundances of 6Li and 7Li.

  13. Analysis of Isotopic Abundance of Plutonium by Multicollector-Inductively Coupled Plasma Mass Spectrometry%多接收电感耦合等离子体质谱法测量痕量钚同位素

    张继龙; 王同兴; 李力力; 常志远; 赵永刚; 刘俊岭

    2005-01-01

    The isotopic analysis of 232Pu plutonium in 5×10-12 g/g samples using a multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) is described. IRMM-290b and uranium (UTB750) were used to correct the metrical data, and the analytical precision is about 0.5%.

  14. Isotopic compositions of boron in sediments and their implications

    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...

  15. Isotopic Biogeochemistry

    Hayes, J. M.

    1985-01-01

    An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

  16. Accurate Determination of 13 C Isotopic Abundances of Free Intracellular Amino acids with Low Concentration by GC-MS-Selective Ion Monitoring Method%气相色谱-质谱联用选择离子监测方法定量分析低浓度胞内游离氨基酸的13 C同位素丰度

    李敏超; 黄明志; 刘玉伟; 储炬; 庄英萍; 张嗣良

    2014-01-01

    13 C isotopic abundance of intracellular free amino acid with a characteristic of fast- turnover can quickly reflect changes in intracellular metabolic state. But the concentration of intracellular free amino acid is low, the existed 13 C isotope detection method based on GC-MS can not satisfy the requirement with full scan mode. In this study, the selected ion monitoring method was used to detect accuracy higher likelihood of analysis of 13 C isotopic abundance of free intracellular amino acid. First, in the full scan mode we analyzed of the fracture law of different amino acids, found the feature corresponding to each amino acid fragments, and established 16 kinds of free intracellular amino acids characteristic fragment library. Then using this characteristic fragment library, only specific m/z signal was detected in sample analysis, which realized the selected ion monitoring and improved the quality of signal. The results of amino acid standards showed that the signal-to-noise ratio, measurement precision and accuracy were improved by 17, 2. 0 and 3. 8 times compared with the full scan mode. In the analysis of coenzyme Q10 producing strains of samples, this method was successfully used to detect isotopic abundance of 8 kinds of free intracellular amino acids. This method plays an important role in the detection of 13 C isotopic abundance of the intracellular free amino acid in cell metabolism research.%胞内游离氨基酸具有周转快的特点,其13 C同位素丰度能快速反映胞内代谢状态的变化。但胞内游离氨基酸的浓度很低,现有的基于气相色谱-质谱联用全扫描模式的13 C同位素丰度检测方法不能满足要求。本研究考察理论上检测精度更高的选择离子监测方法在胞内游离氨基酸13 C同位素丰度分析中应用的可能性。首先在全扫描模式下分析了不同氨基酸的断裂规律,找出与每种氨基酸对应的特征碎片,建立起包含有16种胞内游离氨基

  17. New method of the 17 O + p reaction rate determination by means of the measurement of the partial widths of 18 F levels. Consequences on the oxygen isotopes abundance ratio of red giant stars

    The 17 O destruction by the CNO cycle in the 17 O (p, α) 14 N and 17 O(p, γ) 18 F reactions is studied. The consequences on the isotropic abundance ratio at the surface of some red giants and supergiants, with mass values about 2 and 15 of the solar mass, are discussed. The results of the energy measurements of the first level and above the threshold value of 17 O + p are reported, as well as the tranfer reaction formulation. The utilization of the new reaction ratio in the evolution and stellar nucleosynthesis is explained. The results are in good agreement with the most part of the observations performed

  18. Actinide isotopic analysis systems

    This manual provides instructions and procedures for using the Lawrence Livermore National Laboratory's two-detector actinide isotope analysis system to measure plutonium samples with other possible actinides (including uranium, americium, and neptunium) by gamma-ray spectrometry. The computer program that controls the system and analyzes the gamma-ray spectral data is driven by a menu of one-, two-, or three-letter options chosen by the operator. Provided in this manual are descriptions of these options and their functions, plus detailed instructions (operator dialog) for choosing among the options. Also provided are general instructions for calibrating the actinide isotropic analysis system and for monitoring its performance. The inventory measurement of a sample's total plutonium and other actinides content is determined by two nondestructive measurements. One is a calorimetry measurement of the sample's heat or power output, and the other is a gamma-ray spectrometry measurement of its relative isotopic abundances. The isotopic measurements needed to interpret the observed calorimetric power measurement are the relative abundances of various plutonium and uranium isotopes and americium-241. The actinide analysis system carries out these measurements. 8 figs

  19. 2. Workshop 'Isotopes in Nature'. 1

    The workshop was aimed at discussing in detail the following problems: (1) distribution of stable and radioactive isotopes in nature, (2) theoretical and experimental studies of isotopic effects in natural processes, (3) problems of sample preparation and sample measurement in determining the relative abundance of stable isotopes or radioactive isotopes in nature, (4) age estimations of samples from different areas of the geosphere, (5) contributions to the specification of global and regional substance cycles in nature with the aid of isotopic and geochemical studies. 75 summaries are included

  20. Isotopic geology

    Born from the application to geology of nuclear physics techniques, the isotopic geology has revolutionized the Earth's sciences. Beyond the dating of rocks, the tracer techniques have permitted to reconstruct the Earth's dynamics, to measure the temperatures of the past (giving birth to paleoclimatology) and to understand the history of chemical elements thanks to the analysis of meteorites. Today, all domains of Earth sciences appeal more or less to the methods of isotopic geology. In this book, the author explains the principles, methods and recent advances of this science: 1 - isotopes and radioactivity; 2 - principles of isotope dating; 3 - radio-chronological methods; 4 - cosmogenic isotope chronologies; 5 - uncertainties and radio-chronological results; 6 - geochemistry of radiogenic isotopes; 7 - geochemistry of stable isotopes; 8 - isotopic geology and dynamical analysis of reservoirs. (J.S.)

  1. Isotopic clusters

    Spectra of isotopically mixed clusters (dimers of SF6) are calculated as well as transition frequencies. The result leads to speculations about the suitability of the laser-cluster fragmentation process for isotope separation. (Auth.)

  2. New approaches to the Moon's isotopic crisis

    Melosh, H. J.

    2014-01-01

    Recent comparisons of the isotopic compositions of the Earth and the Moon show that, unlike nearly every other body known in the Solar System, our satellite's isotopic ratios are nearly identical to the Earth's for nearly every isotopic system. The Moon's chemical make-up, however, differs from the Earth's in its low volatile content and perhaps in the elevated abundance of oxidized iron. This surprising situation is not readily explained by current impact models of the Moon's origin and offe...

  3. Precision Chemical Abundance Measurements

    Yong, David; Grundahl, Frank; Meléndez, Jorge;

    2012-01-01

    This talk covers preliminary work in which we apply a strictly differential line-by-line chemical abundance analysis to high quality UVES spectra of the globular cluster NGC 6752. We achieve extremely high precision in the measurement of relative abundance ratios. Our results indicate that the ob...

  4. Abrupt sea surface pH change at the end of the Younger Dryas in the central sub-equatorial Pacific inferred from boron isotope abundance in corals (Porites

    A. Juillet-Leclerc

    2010-08-01

    Full Text Available The "δ11B-pH" technique was applied to modern and ancient corals Porites from the sub-equatorial Pacific areas (Tahiti and Marquesas spanning a time interval from 0 to 20.720 calendar years to determine the amplitude of pH changes between the Last Glacial Period and the Holocene. Boron isotopes were measured by Multi-Collector – Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS with an external reproducibility of 0.25‰, allowing a precision of about ±0.03 pH-units for pH values between 8 and 8.3. The boron concentration [B] and isotopic composition of modern samples indicate that the temperature strongly controls the partition coefficient KD for different aragonite species. Modern coral δ11B values and the reconstructed sea surface pH values for different Pacific areas match the measured pH expressed on the seawater scale and confirm the calculation parameters that were previously determined by laboratory calibration exercises. Most ancient sea surface pH reconstructions near Marquesas are higher than modern values. These values range between 8.19 and 8.27 for the Holocene and reached 8.30 at the end of the last glacial period (20.7 kyr BP. At the end of the Younger Dryas (11.50±0.1 kyr BP, the central sub-equatorial Pacific experienced a dramatic drop of up to 0.2 pH-units from the average pH of 8.2 before and after this short event. Using the marine carbonate algorithms, we recalculated the aqueous pCO2 to be 440±25 ppmV at around 11.5 kyr BP for corals at Marquesas and ~500 ppmV near Tahiti where it was assumed that pCO2 in the atmosphere was 250 ppmV. Throughout the Holocene, the difference in pCO2 between the ocean and the atmosphere at Marquesas (ΔpCO2 indicates that the surface waters behave as a moderate CO2 sink or source (−53 to 20 ppmV during El Niño-like conditions. By contrast, during the last glacial/interglacial transition, this area was a marked source of CO2 (21 to 92 ppmV for the atmosphere, highlighting

  5. Experiences in Uranium Abundance Analysis Using the MTE Methodology

    BLACK CLAUDIE KATE; Zuleger, Evelyn; HORTA DOMENECH Joan; VARGAS ZUNIGA Martin

    2012-01-01

    The ITU in Karlsruhe routinely analyses a multitude of samples from a wide range of internal and external customers for safeguards. High through-put analysis techniques are employed using meticulous care to ensure accurate, precise and timely results are provided. Thermal ionisation mass spectrometry (TIMS) is used for isotopic analysis of Uranium to determine abundance and concentration information. At ITU we employ the modified total evaporation (MTE) methodology[1] for minor isotope an...

  6. Isotope separation of gadolinium using optical pumping

    The gadolinium atoms in the 533 cm-1 metastable level were photoionized by pulsed laser beams after the population of 160Gd in the 533 cm-1 metastable level had been reduced by optical pumping using a continuous wave ring dye laser. Mass spectra of the ionized gadolinium atoms showed that an abundance ratio of 160Gd decreased from natural isotope abundance of 21.8 % to 1 %. This result demonstrates the isotope separation by photoionization of the atoms after decreasing of the photoionized level population of selected isotope using optical pumping. (author)

  7. Developing a Clinically Useful Calcium Isotope Biomarker

    Romaniello, Stephen J.; Anbar, Ariel D.; Gordon, Gwyneth W.; Skulan, Joseph L.; Smith, Scott M.; Zwart, Sara R.; Monge, Jorge; Fonseca, Rafael

    2016-01-01

    Naturally-occurring Ca is mixture of six isotopes Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48). Biological reaction rates and equilibrium constants depend slightly, but measurably, on atomic mass, causing the relative abundances of Ca isotopes to vary between different tissues. During bone formation, light isotopes of Ca are preferentially incorporated into bone, leaving soft tissue depleted in light isotopes. In contrast, bone resorption exhibits no isotopic preference, and thus transfers the light isotope signature of bone back to soft tissue. This balance makes the Ca isotope composition of soft tissue (e.g. serum, urine) a highly sensitive, quantitative tracer for whole-body bone mineral balance (BMB).

  8. Isotopic fingerprints in surficial waters : Stable isotope methods applied in hydrogeological studies

    Kortelainen, Nina

    2007-01-01

    The driving force behind this study has been the need to develop and apply methods for investigating the hydrogeochemical processes of significance to water management and artificial groundwater recharge. Isotope partitioning of elements in the course of physicochemical processes produces isotopic variations to their natural reservoirs. Tracer property of the stable isotope abundances of oxygen, hydrogen and carbon has been applied to investigate hydrogeological processes in Finland. The work...

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

    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.

  10. Ultrasensitive laser isotope analysis of krypton in an ion storage ring

    A new instrument is being developed for ultrasensitive isotope analysis that combines magnetic mass selection, resonant charge exchange, and laser reionization. For krypton, this technique is expected to achieve isotope abundance sensitivities better than 10-12. (author)

  11. Orion A helium abundance

    The 22.4-GHz (H,He)66-alpha and 36.5-GHz (H,He)56-alpha radio recombination lines have been observed at several Jaffe-Pankonin positions in the central part of the Orion A source. The measured relative abundance of ionized helium increases with distance, averaging 11.6 percent at peripheral points. The observed behavior is interpreted by a blister-type model nebula, which implies that Orion A has a true He abundance of 12 percent, is moving with a radial velocity of 5 km/sec, and is expanding. 18 references

  12. Calculation of isotope shifts and relativistic shifts in CI, CII, CIII and CIV

    Berengut, J. C.; Flambaum, V. V.; Kozlov, M. G.

    2005-01-01

    We present an accurate ab initio method of calculating isotope shifts and relativistic shifts in atomic spectra. We test the method on neutral carbon and three carbon ions. The relativistic shift of carbon lines may allow them to be included in analyses of quasar absorption spectra that seek to measure possible variations in the fine structure constant, alpha, over the lifetime of the Universe. Carbon isotope shifts can be used to measure isotope abundances in gas clouds: isotope abundances a...

  13. Abundant Solar Nebula Solids in Comets

    Messenger, S.; Keller, L. P.; Nakamura-Messenger, K.; Nguyen, A. N.; Clemett, S.

    2016-01-01

    Comets have been proposed to consist of unprocessed interstellar materials together with a variable amount of thermally annealed interstellar grains. Recent studies of cometary solids in the laboratory have shown that comets instead consist of a wide range of materials from across the protoplanetary disk, in addition to a minor complement of interstellar materials. These advances were made possible by the return of direct samples of comet 81P/Wild 2 coma dust by the NASA Stardust mission and recent advances in microscale analytical techniques. Isotopic studies of 'cometary' chondritic porous interplanetary dust particles (CP-IDPs) and comet 81P/Wild 2 Stardust samples show that preserved interstellar materials are more abundant in comets than in any class of meteorite. Identified interstellar materials include sub-micron-sized presolar silicates, oxides, and SiC dust grains and some fraction of the organic material that binds the samples together. Presolar grain abundances reach 1 weight percentage in the most stardust-rich CP-IDPs, 50 times greater than in meteorites. Yet, order of magnitude variations in presolar grain abundances among CP-IDPs suggest cometary solids experienced significant variations in the degree of processing in the solar nebula. Comets contain a surprisingly high abundance of nebular solids formed or altered at high temperatures. Comet 81P/Wild 2 samples include 10-40 micron-sized, refractory Ca- Al-rich inclusion (CAI)-, chondrule-, and ameboid olivine aggregate (AOA)-like materials. The O isotopic compositions of these refractory materials are remarkably similar to their meteoritic counterparts, ranging from 5 percent enrichments in (sup 16) O to near-terrestrial values. Comet 81P/Wild 2 and CP-IDPs also contain abundant Mg-Fe crystalline and amorphous silicates whose O isotopic compositions are also consistent with Solar System origins. Unlike meteorites, that are dominated by locally-produced materials, comets appear to be composed of

  14. Natural fractionation of uranium isotopes

    The topic of this thesis was the investigation of U (n(238U) / n(235U)) 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(238U) and n(235U), on Earth.

  15. Leatherback Isotopes

    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...

  16. Applications of abundance data and requirements for cosmochemical modeling

    Busemann, H.; Binns, W. R.; Chiappini, C.; Gloeckler, G.; Hoppe, P.; Kirilova, Donka; Leske, R. A.; Manuel, O. K.; Wiens, R. C. (Roger C.)

    2001-01-01

    Understanding the evolution of the universe from Big Bang to its present state requires an understanding of the evolution of the abundances of the elements and isotopes in galaxies, stars, the interstellar medium, the Sun and the heliosphere, planets and meteorites. Processes that change the state of the universe include Big Bang nucleosynthesis, star formation and stellar nucleosynthesis, galactic chemical evolution, propagation of cosmic rays, spallation, ionization and particle transport of interstellar material, formation of the solar system, solar wind emission and its fractionation (FIP/FIT effect), mixing processes in stellar interiors, condensation of material and subsequent geochemical fractionation. Here, we attempt to compile some major issues in cosmochemistry that can be addressed with a better knowledge of the respective element or isotope abundances. Present and future missions such as Genesis, Stardust, Interstellar Pathfinder, and Interstellar Probe, improvements of remote sensing instrumentation and experiments on extraterrestrial material such as meteorites, presolar grains, and lunar or returned planetary or cometary samples will result in an improved database of elemental and isotopic abundances. This includes the primordial abundances of D, 3He, 4He, and 7Li, abundances of the heavier elements in stars and galaxies, the composition of the interstellar medium, solar wind and comets as well as the (highly) volatile elements in the solar system such as helium, nitrogen, oxygen or xenon.

  17. Isotopic chirality

    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.

  18. A pedagogy of abundance

    Weller, Martin

    2011-01-01

    The digitisation of content combined with a global network for delivery and an open system for sharing has seen radical changes in many industries. The economic model which has underpinned many content based industries has been based on an assumption of scarcity. With a digital, open, networked approach we are witnessing a shift to abundance of content, and subsequently new economic models are being developed which have this as an assumption. In this article the role of scarcity in developing...

  19. Interstellar Atomic Abundances

    Jenkins, E B

    2003-01-01

    A broad array of interstellar absorption features that appear in the ultraviolet spectra of bright sources allows us to measure the abundances and ionization states of many important heavy elements that exist as free atoms in the interstellar medium. By comparing these abundances with reference values in the Sun, we find that some elements have abundances relative to hydrogen that are approximately consistent with their respective solar values, while others are depleted by factors that range from a few up to around 1000. These depletions are caused by the atoms condensing into solid form onto dust grains. Their strengths are governed by the volatility of compounds that are produced, together with the densities and velocities of the gas clouds. We may characterize the depletion trends in terms of a limited set of parameters; ones derived here are based on measurements of 15 elements toward 144 stars with known values of N(H I) and N(H2). In turn, these parameters may be applied to studies of the production, de...

  20. Abundances in galaxies

    Standard (or mildly inhomogeneous) Big Bang nucleosynthesis theory is well confirmed by abundance measurements of light elements up to 7Li and the resulting upper limit to the number of neutrino families confirmed in accelerator experiments. Extreme inhomogeneous models with a closure density in form of baryons seem to be ruled out and there is no evidence for a cosmic 'floor' to 9Be or heavier elements predicted in some versions of those models. Galaxies show a correlation between luminous mass and abundance of carbon and heavier elements, usually attributed to escape of hot gas from shallow potential wells. Uncertainties include the role of dark matter and biparametric behaviour of ellipticals. Spirals have radial gradients which may arise from a variety of causes. In our own Galaxy one can distinguish three stellar populations - disk, halo and bulge - characterised by differing metallicity distribution functions. Differential abundance effects are found among different elements in stars as a function of metallicity and presumably age, notably in the ratio of oxygen and α-particle elements to iron. These may eventually be exploitable to set a time scale for the formation of the halo, bulge and disk. (orig.)

  1. Isotope ratio in stellar atmospheres and nucleosynthesis

    The determination of isotopic ratios in stellar atmospheres is studied. The isotopic shift of atomic and molecular lines of different species of a certain element is examined. CH and MgH lines are observed in order to obtain the 12C: 13C and 24Mg: 25Mg: 26Mg isotpic ratios. The formation of lines in stellar atmospheres is computed and the resulting synthetic spectra are employed to determine the isotopic abundances. The results obtained for the isotopic ratios are compared to predictions of nucleosynthesis theories. Finally, the concept of primary and secondary element is discussed, and these definitions are applied to the observed variations in the abundance of elements as a function of metallicity. (author)

  2. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems

    Lepoint, Gilles; Dauby, Patrick; Gobert, Sylvie

    2004-01-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure o...

  3. Laser Ablation Molecular Isotopic Spectrometry: Parameter influence on boron isotope measurements

    Laser Ablation Molecular Isotopic Spectrometry (LAMIS) was recently reported for optical isotopic analysis of condensed samples in ambient air and at ambient pressure. LAMIS utilizes molecular emissions which exhibit larger isotopic spectral shits than in atomic transitions. For boron monoxide 10BO and 11BO, the isotopic shifts extend from 114 cm-1 (0.74 nm) to 145-238 cm-1 (5-8 nm) at the B2Σ+ (v = 0) → X2Σ+ (v = 2) and A2Πi (v = 0) → X2Σ+ (v = 3) transitions, respectively. These molecular isotopic shifts are over two orders of magnitude larger than the maximum isotopic shift of approximately 0.6 cm-1 in atomic boron. This paper describes how boron isotope abundance can be quantitatively determined using LAMIS and how atomic, ionic, and molecular optical emission develops in a plasma emanating from laser ablation of solid samples with various boron isotopic composition. We demonstrate that requirements for spectral resolution of the measurement system can be significantly relaxed when the isotopic abundance ratio is determined using chemometric analysis of spectra. Sensitivity can be improved by using a second slightly delayed laser pulse arriving into an expanding plume created by the first ablation pulse.

  4. The isotope correlation experiment

    The ESARDA working group on Isotopic Correlation Techniques, ICT and Reprocessing Input Analysis performed an Isotope Correlation Experiment, ICE with the aim to check the feasibility of the new technique. Ten input batches of the reprocessing of the KWO fuel at the WAK plant were analysed by 4 laboratories. All information to compare ICT with the gravimetric and volumetric methods was available. ICT combined with simplified reactor physics calculation was included. The main objectives of the statistical data evaluation were detection of outliers, the estimation of random errors and of systematic errors of the measurements performed by the 4 laboratories. Different methods for outlier detection, analysis of variances, Grubbs' analysis for the constant-bias model and Jaech's non-constant-bias model were applied. Some of the results of the statistical analysis may seem inconsistent which is due to the following reasons. For the statistical evaluations isotope abundance data (weight percent) as well as nuclear concentration data (atoms/initial metal atoms) were subjected to different outlier criteria before being used for further statistical evaluations. None of the four data evaluation groups performed a complete statistical data analysis which would render possible a comparison of the different methods applied since no commonly agreed statistical evaluation procedure existed. The results prove that ICT is as accurate as conventional techniques which have to rely on costly mass spectrometric isotope dilution analysis. The potential of outlier detection by ICT on the basis of the results from a single laboratory is as good as outlier detection by costly interlaboratory comparison. The application of fission product or Cm-244 correlations would be more timely than remeasurements at safeguards laboratories

  5. Absolute Quantification of Endogenous Ras Isoform Abundance.

    Craig J Mageean

    Full Text Available Ras proteins are important signalling hubs situated near the top of networks controlling cell proliferation, differentiation and survival. Three almost identical isoforms, HRAS, KRAS and NRAS, are ubiquitously expressed yet have differing biological and oncogenic properties. In order to help understand the relative biological contributions of each isoform we have optimised a quantitative proteomics method for accurately measuring Ras isoform protein copy number per cell. The use of isotopic protein standards together with selected reaction monitoring for diagnostic peptides is sensitive, robust and suitable for application to sub-milligram quantities of lysates. We find that in a panel of isogenic SW48 colorectal cancer cells, endogenous Ras proteins are highly abundant with ≥260,000 total Ras protein copies per cell and the rank order of isoform abundance is KRAS>NRAS≥HRAS. A subset of oncogenic KRAS mutants exhibit increased total cellular Ras abundance and altered the ratio of mutant versus wild type KRAS protein. These data and methodology are significant because Ras protein copy number is required to parameterise models of signalling networks and informs interpretation of isoform-specific Ras functional data.

  6. Deconstructing nitrate isotope dynamics in aquifers

    Granger, J.

    2012-12-01

    The natural abundance N and O stable isotope ratios of nitrate provide an invaluable tool to differentiate N sources to the environment, track their dispersal, and monitor their attenuation by biological transformations. The interpretation of patterns in isotope abundances relies on knowledge of the isotope ratios of the source end-members, as well as on constraints on the isotope discrimination imposed on nitrate by respective biological processes. Emergent observations from mono-culture experiments of denitrifying bacteria reveal nitrate fractionation trends that appear at odds with trends ascribed to denitrification in soils and aquifers. This discrepancy raises the possibility that additional biological N transformations may be acting in tandem with denitrification. Here, the N and O isotope enrichments associated with nitrate removal by denitrification in aquifers are posited to bear evidence of coincident biological nitrate production - from nitrification and/or from anammox. Simulations are presented from a simple time-dependent one-box model of a groundwater mass ageing that is subject to net nitrate loss by denitrification with coincident nitrate production by nitrification or anammox. Within boundary conditions characteristic of freshwater aquifers, the apparent slope of the parallel enrichments in nitrate N and O isotopes associated with net N loss to denitrification can vary in proportion to the nitrate added simultaneous by oxidative processes. Pertinent observations from nitrate plumes in suboxic to anoxic aquifers are examined to validate this premise. In this perspective, nitrate isotope distributions suggest that we may be missing important N fluxes inherent to most aquifers.

  7. Abundance, Excess, Waste

    Rox De Luca

    2016-02-01

    Her recent work focuses on the concepts of abundance, excess and waste. These concerns translate directly into vibrant and colourful garlands that she constructs from discarded plastics collected on Bondi Beach where she lives. The process of collecting is fastidious, as is the process of sorting and grading the plastics by colour and size. This initial gathering and sorting process is followed by threading the components onto strings of wire. When completed, these assemblages stand in stark contrast to the ease of disposability associated with the materials that arrive on the shoreline as evidence of our collective human neglect and destruction of the environment around us. The contrast is heightened by the fact that the constructed garlands embody the paradoxical beauty of our plastic waste byproducts, while also evoking the ways by which those byproducts similarly accumulate in randomly assorted patterns across the oceans and beaches of the planet.

  8. Atlas of isotope hydrology - Africa

    Although there are abundant water resources in Africa - about 17 large rivers and 160 lakes greater than 27 km2 - most of these resources are located in the humid and sub-humid regions around the equator. The surface runoff in Africa, on average, is much lower than average precipitation as a result of high evaporation and evapotranspiration, resulting in endemic drought in parts of the continent. Consequently, groundwater is a very important resource for Africa, providing nearly two-thirds of drinking water on the continent, and an even greater proportion in northern Africa. Despite the importance of groundwater for many societies, there is a lack of corresponding public concern about its protection, perhaps because the extent and availability of groundwater are not easily measured. The impact of increasing degrees of temporal and spatial climatic variability on water resources is also an important consideration, and groundwater to some extent provides an opportunity to mitigate the impacts of climate change. Applications of isotopes in hydrology are based on the general concept of 'tracing', in which naturally occurring or environmental isotopes (either radioactive or stable) are used to study hydrological processes on large temporal and spatial scales through their natural distribution in a hydrological system. Thus, environmental isotope methodologies are unique in regional studies of water resources to obtain integrated characteristics of groundwater systems. The most frequently used environmental isotopes include those of the water molecule, hydrogen (2H or D, also called deuterium, and 3H, also called tritium) and oxygen (18O), as well as of carbon (13C and 14C, also called radiocarbon or carbon-14) occurring in water as constituents of dissolved inorganic and organic carbon compounds. 2H, 13C and 18O are stable isotopes of the respective elements, whereas 3H and 14C are radioactive isotopes. Among the most important areas where isotopes are useful in

  9. Primordial Deuterium Abundance Measurements

    Levshakov, S A; Takahara, F; Levshakov, Sergei A.; Kegel, Wilhelm H.; Takahara, Fumio

    1997-01-01

    Deuterium abundances measured recently from QSO absorption-line systems lie in the range from 3 10^{-5} to 3 10^{-4}, which shed some questions on standard big bang theory. We show that this discordance may simply be an artifact caused by inadequate analysis ignoring spatial correlations in the velocity field in turbulent media. The generalized procedure (accounting for such correlations) is suggested to reconcile the D/H measurements. An example is presented based on two high-resolution observations of Q1009+2956 (low D/H) [1,2] and Q1718+4807 (high D/H) [8,9]. We show that both observations are compatible with D/H = 4.1 - 4.6 10^{-5}, and thus support SBBN. The estimated mean value = 4.4 10^{-5} corresponds to the baryon-to-photon ratio during SBBN eta = 4.4 10^{-10} which yields the present-day baryon density Omega_b h^2 = 0.015.

  10. Principles of isotopic analysis by mass spectrometry

    The use of magnetic sector field mass spectrometers in isotopic analysis, especially for nitrogen gas, is outlined. Two measuring methods are pointed out: the scanning mode for significantly enriched samples and the double collector method for samples near the natural abundance of 15N. The calculation formulas are derived and advice is given for corrections. (author)

  11. Environmental and biomedical applications of natural metal stable isotope variations

    Bullen, T.D.; Walczyk, T.

    2009-01-01

    etal stable isotopes are now being used to trace metal contaminants in the environment and as indicators of human systemic function where metals play a role. Stable isotope abundance variations provide information about metal sources and the processes affecting metals in complex natural systems, complementing information gained from surrogate tracers, such as metal abundance ratios or biochemical markers of metal metabolism. The science is still in its infancy, but the results of initial studies confirm that metal stable isotopes can provide a powerful tool for forensic and biomedical investigations.

  12. Isotopic analysis of bullet lead samples

    The possibility of using the isotopic composition of lead for the identification of bullet lead is investigated. Lead from several spent bullets were converted to lead sulphide and analysed for the isotopic abundances using an MS-7 mass spectrometer. The abundances are measured relative to that for Pb204 was too small to permit differentiation, while the range of variation of Pb206 and Pb207 and the better precision in their analyses permitted differentiating samples from one another. The correlation among the samples examined has been pointed out. The method is complementary to characterisation of bullet leads by the trace element composition. The possibility of using isotopically enriched lead for tagging bullet lead is pointed out. (author)

  13. Abundance and Impact of Doubly Charged Polyatomic Argon Interferences in ICPMS Spectra.

    Hattendorf, Bodo; Gusmini, Bianca; Dorta, Ladina; Houk, Robert S; Günther, Detlef

    2016-07-19

    Doubly charged molecular ions of alkaline earth metals and argon could be identified as spectral interferences in an inductively coupled plasma mass spectrometer. These molecular ions were found to occur at abundances reaching about 10(-4) relative to the alkaline earth atomic ion abundances. They can thus substantially affect ultratrace analyses and, when present at similar concentration as the analyte elements, also isotope ratio measurements. For the case of Cu and Zn isotope ratio analyses, the same mass concentration of Sr was found to alter the measured (63)Cu/(65)Cu and (64)Zn/(66)Zn isotope ratios by -0.036‰ to -0.95‰ due to SrAr(2+), appearing at m/Q 63 and 64. BaAr(2+) can affect Sr isotope analyses, MgAr(2+) may impair S isotope ratio measurements, while CaAr(2+) may cause interference to Ca(+) isotopes. The abundances of the doubly charged molecular ions were higher than those of the corresponding singly charged species, which is in accordance with their generally higher bond dissociation energies. The relative abundances were found to depend significantly on the inductively coupled plasma (ICP) operating conditions and generally increase with increasing carrier gas flow rates or lower gas temperature of the ICP. They also increase by about an order of magnitude when a desolvated aerosol is introduced to the ICP. PMID:27306032

  14. Carbon isotopic fractionation in heterotrophic microbial metabolism

    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.

  15. Solar System Abundances of the Elements

    Lodders, Katharina

    2010-01-01

    Representative abundances of the chemical elements for use as a solar abundance standard in astronomical and planetary studies are summarized. Updated abundance tables for solar system abundances based on meteorites and photospheric measurements are presented.

  16. Nuclides and isotopes. Twelfth edition

    This explanatory booklet was designed to be used with the Chart of the Nuclides. It contains a brief history of the atomic theory of matter: ancient speculations, periodic properties of elements (Mendeleev table), radioactivity, early models of atomic structure, the Bohr atom, quantum numbers, nature of isotopes, artificial radioactivity, and neutron fission. Information on the pre-Fermi (natural) nuclear reactor at Oklo and the search for superheavy elements is given. The booklet also discusses information presented on the Chart and its coding: stable nuclides, metastable states, data display and color, isotopic abundances, neutron cross sections, spins and parities, fission yields, half-life variability, radioisotope power and production data, radioactive decay chains, and elements without names. The Periodic Table of the Elements is appended. 3 figures, 3 tables

  17. An attempt for the precise isotope analysis

    A compact virtual image double focusing mass spectrometer was adopted for the precise isotope analysis with surface ionization ion source. A interface with 16-bit DA converter was set into the computer for automatic control of magnetic field. This new system enabled to measure isotopic ratios by peak hopping method. To obtain high precision, the digital voltmeter under computer control was introduced for collecting data and processing them successively. The flatness of the peak top and the stability of the magnetic field during the single run were checked and found to be satisfactory. For the test of the measuring system, the isotopic ratios of K, Rb and Sr were measured using shelf reagents. It was concluded that (1) by the Faraday collector, the isotopic ratio could be measured with the precision better than 0.01 % when the ion currents for both isotopes were higher than 10-11 A, (2) for the isotope less abundant than 10-4, the precision achieved a few percent by Faraday collector with ion current of 10-15 A, while the precision was within 1 % by SEM collector with ion current of 10-17 A. The performance of the mass spectrometer was found to be satisfactory to measure isotopic ratios with a high precision. (author)

  18. Ultratrace Uranium Fingerprinting with Isotope Selective Laser Ionization Spectrometry

    Uranium isotope ratios can provide source information for tracking uranium contamination in a variety of fields, ranging from occupational bioassay to monitoring aftereffects of nuclear accidents. We describe the development of Isotope Selective Laser Ionization Spectrometry (ISLIS) for ultratrace measurement of the minor isotopes 234U, 235U, and 236U with respect to 238U. Optical isotopic selectivity in three-step excitation with single-mode continuous wave lasers is capable of measuring the minor isotopes at relative abundances below 1 ppm, and is not limited by isobaric interferences such as 235UH+ during measurement of 236U. This relative abundance limit approaches the threshold for measurement of uranium minor isotopes with conventional mass spectrometry, typically 10-7, but without mass spectrometric analysis of the laser-created ions. Uranyl nitrate standards from an international blind comparison were used to test analytical performance for different isotopic compositions and with quantities ranging from 11 ng to 10 (micro)g total uranium. Isotopic ratio determination was demonstrated over a linear dynamic range of 7 orders of magnitude with a few percent relative precision and detection limits below 500 fg for the minor isotopes

  19. Combinatorial effects on clumped isotopes and their significance in biogeochemistry

    Yeung, Laurence Y.

    2016-01-01

    The arrangement of isotopes within a collection of molecules records their physical and chemical histories. Clumped-isotope analysis interrogates these arrangements, i.e., how often rare isotopes are bound together, which in many cases can be explained by equilibrium and/or kinetic isotope fractionation. However, purely combinatorial effects, rooted in the statistics of pairing atoms in a closed system, are also relevant, and not well understood. Here, I show that combinatorial isotope effects are most important when two identical atoms are neighbors on the same molecule (e.g., O2, N2, and D-D clumping in CH4). When the two halves of an atom pair are either assembled with different isotopic preferences or drawn from different reservoirs, combinatorial effects cause depletions in clumped-isotope abundance that are most likely between zero and -1‰, although they could potentially be -10‰ or larger for D-D pairs. These depletions are of similar magnitude, but of opposite sign, to low-temperature equilibrium clumped-isotope effects for many small molecules. Enzymatic isotope-pairing reactions, which can have site-specific isotopic fractionation factors and atom reservoirs, should express this class of combinatorial isotope effect, although it is not limited to biological reactions. Chemical-kinetic isotope effects, which are related to a bond-forming transition state, arise independently and express second-order combinatorial effects related to the abundance of the rare isotope. Heteronuclear moeties (e.g., Csbnd O and Csbnd H), are insensitive to direct combinatorial influences, but secondary combinatorial influences are evident. In general, both combinatorial and chemical-kinetic factors are important for calculating and interpreting clumped-isotope signatures of kinetically controlled reactions. I apply this analytical framework to isotope-pairing reactions relevant to geochemical oxygen, carbon, and nitrogen cycling that may be influenced by combinatorial

  20. The chlorine isotope fingerprint of the lunar magma ocean.

    Boyce, Jeremy W; Treiman, Allan H; Guan, Yunbin; Ma, Chi; Eiler, John M; Gross, Juliane; Greenwood, James P; Stolper, Edward M

    2015-09-01

    The Moon contains chlorine that is isotopically unlike that of any other body yet studied in the Solar System, an observation that has been interpreted to support traditional models of the formation of a nominally hydrogen-free ("dry") Moon. We have analyzed abundances and isotopic compositions of Cl and H in lunar mare basalts, and find little evidence that anhydrous lava outgassing was important in generating chlorine isotope anomalies, because (37)Cl/(35)Cl ratios are not related to Cl abundance, H abundance, or D/H ratios in a manner consistent with the lava-outgassing hypothesis. Instead, (37)Cl/(35)Cl correlates positively with Cl abundance in apatite, as well as with whole-rock Th abundances and La/Lu ratios, suggesting that the high (37)Cl/(35)Cl in lunar basalts is inherited from urKREEP, the last dregs of the lunar magma ocean. These new data suggest that the high chlorine isotope ratios of lunar basalts result not from the degassing of their lavas but from degassing of the lunar magma ocean early in the Moon's history. Chlorine isotope variability is therefore an indicator of planetary magma ocean degassing, an important stage in the formation of terrestrial planets. PMID:26601265

  1. Estimating Animal Abundance: Review III

    Schwarz, Carl J; Seber, George A. F.

    1999-01-01

    The literature describing methods for estimating animal abundance and related parameters continues to grow. This paper reviews recent developments in the subject over the past seven years and updates two previous reviews.

  2. Stable isotope studies

    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.

  3. Stable isotope studies

    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

  4. Method for separating isotopes

    Jepson, B.E.

    1975-10-21

    Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether.

  5. Developing isotopic functions

    Isotopic functions, or ratios of two isotopic variables, are used to verify Pu and U measurements of spent fuels in reprocessing plants. Systematic methods have been developed for forming and evaluating isotopic functions. This paper describes the method used at Battelle to form and evaluate isotopic functions. The data base at Battelle contains measurements and calculations for the fuel from 35 reactors

  6. The isotopic contamination in electromagnetic isotope separators

    In the early years of isotope separation, and in particular electromagnetic isotope separation, needs for rapid results have conducted to empiric research. This paper describes fundamental research on the electromagnetic isotope separation to a better understanding of isotope separators as well as improving the performances. Focus has been made on the study of the principle of isotope contamination and the remedial action on the separator to improve the isotope separation ratio. In a first part, the author come back to the functioning of an electromagnetic separator and generalities on isotope contamination. Secondly, it describes the two stages separation method with two dispersive apparatus, an electromagnetic separation stage followed by an electrostatic separation stage, both separated by a diaphragm. The specifications of the electrostatic stage are given and its different settings and their consequences on isotope separation are investigated. In a third part, mechanisms and contamination factors in the isotope separation are discussed: natural isotope contamination, contamination by rebounding on the collector, contamination because of a low resolution, contamination by chromatism and diffusion effect, breakdown of condenser voltage. Analysis of experimental results shows the diffusion as the most important contamination factor in electromagnetic isotope separation. As contamination factors are dependent on geometric parameters, sector angle, radius of curvature in the magnetic field and clearance height are discussed in a fourth part. The better understanding of the mechanism of the different contamination factors and the study of influential parameters as pressure and geometric parameters lead to define a global scheme of isotope contamination and determinate optima separator design and experimental parameters. Finally, the global scheme of isotope contamination and hypothesis on optima specifications and experimental parameters has been checked during a

  7. Clumped-isotope geochemistry of carbonates: A new tool for the reconstruction of temperature and oxygen isotope composition of seawater

    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.

  8. Isotope studies of dolomite formation under sedimentary conditions

    Clayton, R.N.; Jones, B.F.

    1968-01-01

    Measurements of stable isotope abundances of the carbonate portion of the sediment in Deep Springs Lake, California, indicate the presence of at least three phases: a magnesian calcite, a primary sedimentary dolomite, and a detrital dolomite. The former two have isotopic compositions consistent with precipitation at isotopic equilibrium from waters of the lake area. The measured isotopic fractionation factor between sedimentary dolomite and its interstitial water is 1.0351, which is outside the range possible for calcite-water. This indicates that the dolomite has formed by direct crystallization from solution and not from a caloite precursor without further isotope exchange. Isotopic and X-ray evidence does not support the contention of Peterson et al. (1966) that Deep Springs Lake dolomite crystals grow by means of a calcite-like surface layer. ?? 1968.

  9. Chlorine Abundances in Cool Stars

    Maas, Z G; Hinkle, K

    2016-01-01

    Chlorine abundances are reported in 15 evolved giants and one M dwarf in the solar neighborhood. The Cl abundance was measured using the vibration-rotation 1-0 P8 line of H$^{35}$Cl at 3.69851 $\\mu$m. The high resolution L-band spectra were observed using the Phoenix infrared spectrometer on the Kitt Peak Mayall 4m telescope. The average [$^{35}$Cl/Fe] abundance in stars with --0.72$<$[Fe/H]$<$0.20 is [$^{35}$Cl/Fe]=(--0.10$\\pm$0.15) dex. The mean difference between the [$^{35}$Cl/Fe] ratios measured in our stars and chemical evolution model values is (0.16$\\pm$0.15) dex. The [$^{35}$Cl/Ca] ratio has an offset of $\\sim$0.35 dex above model predictions suggesting chemical evolution models are under producing Cl at the high metallicity range. Abundances of C, N, O, Si, and Ca were also measured in our spectral region and are consistent with F and G dwarfs. The Cl versus O abundances from our sample match Cl abundances measured in planetary nebula and \\ion{H}{2} regions. In one star where both H$^{35}$Cl a...

  10. Isotopic fractionation of zinc in tektites

    Moynier, Frederic; Beck, Pierre; Jourdan, Fred; Yin, Qing-Zhu; Reimold, Uwe; Koeberl, Christian

    2009-01-01

    Tektites are terrestrial natural glasses produced during a hypervelocity impact of an extraterrestrial projectile onto the Earth's surface. The similarity between the chemical and isotopic compositions of tektites and terrestrial upper continental crust implies that the tektites formed by fusion of such target rock. Tektites are among the driest rocks on Earth. Although volatilization at high temperature may have caused this extreme dryness, the exact mechanism of the water loss and the behavior of other volatile species during tektite formation are still debated. Volatilization can fractionate isotopes, therefore, comparing the isotope composition of volatile elements in tektites with that of their source rocks may help to understand the physical conditions during tektite formation. For this study, we have measured the Zn isotopic composition of 20 tektites from four different strewn fields. Almost all samples are enriched in heavy isotopes of Zn compared to the upper continental crust. On average, the different groups of tektites are isotopically distinct (listed from the isotopically lightest to the heaviest): Muong-Nong type indochinites ( δ66/64Zn = 0.61 ± 0.30‰); North American bediasites ( δ66/64Zn = 1.61 ± 0.49‰); Ivory Coast tektites ( δ66/64Zn = 1.66 ± 0.18‰); the Australasian tektites (others than the Muong Nong-type indochinites) ( δ66/64Zn = 1.84 ± 0.42‰); and Central European moldavites ( δ66/64Zn = 2.04 ± 0.19‰). These results are contrasted with a narrow range of δ66/64Zn = 0-0.7‰ for a diverse spectrum of upper continental crust materials. The elemental abundance of Zn is negatively correlated with δ66/64Zn, which may reflect that isotopic fractionation occurred by evaporation during the heating event upon tektite formation. Simple Rayleigh distillation predicts isotopic fractionations much larger than what is actually observed, therefore, such a model cannot account for the observed Zn isotope fractionation in tektites. We

  11. Chlorine Isotopes: As a Possible Tracer of Fluid/Bio-Activities on Mars and a Progress Report on Chlorine Isotope Analysis by TIMs

    Nakamura, N.; Nyquist, L.E.; Reese, Y.; Shih, C-Y.; Numata, M.; Fujitani, T.; Okano, O.

    2009-01-01

    Significantly large mass fractionations between chlorine isotopes (Cl-35, Cl-37) have been reported for terrestrial materials including both geological samples and laboratory materials. Also, the chlorine isotopic composition can be used as a tracer for early solar system processes. Moreover, chlorine is ubiquitous on the Martian surface. Typical chlorine abundances in Gusev soils are approx.0.5 %. The global surface average chlorine abundance also is approx.0.5 %. Striking variations among outcrop rocks at Meridiani were reported with some chlorine abundances as high as approx.2%. Characterizing conditions under which chlorine isotopic fractionation may occur is clearly of interest to planetary science. Thus, we have initiated development of a chlorine isotopic analysis technique using TIMS at NASA-JSC. We present here a progress report on the current status of development at JSC and discuss the possible application of chlorine isotopic analysis to Martian meteorites in a search for fluid- and possibly biological activity on Mars.

  12. Separation of uranium isotopes

    This invention provides a method for separating uranium isotopes comprising the steps of selectively irradiating a photochemically-reactive uranyl source material at a wavelength selective to a desired isotope of uranium at an effective temperature for isotope spectral line splitting below about 77 K, further irradiating the source material within the fluorescent lifetime of the selectively irradiated source material to selectively photochemically reduce the selectively excited isotopic species, and chemically separating the reduced isotope species from the remaining uranyl salt compound

  13. A mass spectrometric strategy for absolute quantification of Plasmodium falciparum proteins of low abundance

    Hyde John E

    2011-10-01

    Full Text Available Abstract Selected reaction monitoring mass spectrometry has been combined with the use of an isotopically labelled synthetic protein, made up of proteotypic tryptic peptides selected from parasite proteins of interest. This allows, for the first time, absolute quantification of proteins from Plasmodium falciparum. This methodology is demonstrated to be of sufficient sensitivity to quantify, even within whole cell extracts, proteins of low abundance from the folate pathway as well as more abundant "housekeeping" proteins.

  14. On the abundances of carbon dioxide isotopologues in the atmospheres of mars and earth

    Shved, G. M.

    2016-03-01

    The isotopic composition of carbon dioxide in the Martian atmosphere from the measurements of Mars Science Laboratory have been used to estimate the relative abundances of CO2 isotopologues in the Martian atmosphere. Concurrently, this study has revealed long-standing errors in the amounts of some of low-abundance CO2 isotopologues in the Earth's atmosphere in the databases of spectroscopic parameters of gases (HITRAN, etc.).

  15. Stable Vanadium Isotope Fractionation at High Temperatures

    Prytulak, J.; Parkinson, I. J.; Savage, P. S.; Nielsen, S. G.; Halliday, A. N.

    2011-12-01

    Vanadium is a redox sensitive transition metal existing in multiple valence states at terrestrial conditions. Stable vanadium isotopes (reported as δ51V in % relative to an Alfa Aesar standard [1]) are a potentially powerful tracer of oxidation-reduction processes. However, the determination of δ51V is analytically challenging, primarily due to the extreme abundance ratio between the only two stable isotopes (51V/50V ~ 400) and, also, significant isobaric interferences of 50Ti and 50Cr on the minor 50V isotope. We have developed the first method able to determine δ51V to a precision (2 s.d. ~ 0.15%, [1,2]) that enables application of this isotope system to geological processes. To usefully investigate high temperature processes using vanadium isotopes, knowledge of the isotope composition and range of values present in the ambient mantle is required. Here we discuss the first δ51V measured in igneous materials encompassing peridotites, MORB, and primitive mantle-derived melts such as picrites. This first dataset provides a preliminary reconnaissance of the magnitude of natural fractionation. We find little isotope fractionation in suites of peridotites and MORB (vanadium isotope fractionation that may be expected at high temperatures. The presence of significant isotope variation outside of analytical precision in these materials bodes well for the use of δ51V to address a variety of broad scale questions in high temperature planetary processes. [1] Nielsen, S.G., Prytulak, J., Halliday, A.N. 2011. Geost. Geoanal. Res., in press. [2] Prytulak, J., Nielsen, S.G., Halliday, A.N. 2011. Geost. Geoanal. Res., in press. [3] Parkinson and Pearce, 1998. Journal of Petrology, 39, 1577-1618. [4] Lee et al., 2005. Journal of Petrology, 46, 2313-2336. [5] Cottrell and Kelley, 2011. Earth and Planetary Sciences Letters, 305, 270-282.

  16. Abundance anomaly of the 13C species of CCH

    Sakai, N.; Saruwatari, O.; Sakai, T.; Takano, S.; Yamamoto, S.

    2010-03-01

    Aims: We have observed the N = 1-0 lines of CCH and its 13C isotopic species toward a cold dark cloud, TMC-1 and a star-forming region, L1527, to investigate the 13C abundances and formation pathways of CCH. Methods: The observations have been carried out with the IRAM 30 m telescope. Results: We have successfully detected the lines of 13CCH and C13CH toward the both sources and found a significant intensity difference between the two 13C isotopic species. The [C13CH] /[13CCH] abundance ratios are 1.6 ± 0.4 (3σ) and 1.6 ± 0.1 (3σ) for TMC-1 and L1527, respectively. The abundance difference between C13CH and 13CCH means that the two carbon atoms of CCH are not equivalent in the formation pathway. On the other hand, the [CCH]/[C13CH] and [CCH]/[13CCH] ratios are evaluated to be larger than 170 and 250 toward TMC-1, and to be larger than 80 and 135 toward L1527, respectively. Therefore, both of the 13C species are significantly diluted in comparison with the interstellar 12C/13C ratio of 60. The dilution is discussed in terms of a behavior of 13C in molecular clouds.

  17. Stable isotopes: Natural and anthropogenic sulphur in the environment

    This synthesis draws on the results of a major international scientific workshop held in Pushchino (Moscow Region) in summer 1983, organised jointly by the United Nations Environment Programme (UNEP) and SCOPE, with major financial support from UNEP. Variations in the abundances of stable isotopes provide a more universal label for monitoring the global cycling of sulphur. By measuring isotope abundances of a natural sample, information can be gained about its past geochemistry. In controlled laboratory studies, isotope fractionation can be measured and the data used to interpret natural isotope variations. There are two extremes in stable isotope investigations. Isotopic selectivity provides information about a process, but The isotopic composition of an element can be used to follow its fate in the environment, if isotope fractionation is either possible to evaluate. Fortunately, there are a number of processes in which sulphur isotope selectivity is small or non-existent. These include certain high-temperature industrial processes, oxidation of H2S, SO2, etc. in the atmosphere, solid phase reactions proceeding layer by layer, and assimilation of SO42- by bacteria and plants. The current volume strives to show how stable isotope abundances may be used to differentiate between natural and anthropogenic sulphur in the environment. It is intended to serve as a handbook. To this end, basic principles and analytical techniques are included as well as documentation of relevant research in different parts of the world. Case studies which range from situations where the expertise is well developed to the identification of potential research areas are presented. Refs., figs. and tabs

  18. Carbon Isotope Chemistry in Molecular Clouds

    Robertson, Amy N.; Willacy, Karen

    2012-01-01

    Few details of carbon isotope chemistry are known, especially the chemical processes that occur in astronomical environments like molecular clouds. Observational evidence shows that the C-12/C-13 abundance ratios vary due to the location of the C-13 atom within the molecular structure. The different abundances are a result of the diverse formation pathways that can occur. Modeling can be used to explore the production pathways of carbon molecules in an effort to understand and explain the chemical evolution of molecular clouds.

  19. Nitrogen 15 abundance in protein fractions of beans fertilized with (15NH42SO4

    Chaud Saula Goulart

    2002-01-01

    Full Text Available Studies evaluating the protein nutritive value of beans labelled with 15N, ussing nitrogen balance and the quantitation of faecal and urinary endogenous nitrogen, determined by isotopic dilution, have been extensively used. The objective of this research was to verify if the isotopic labelling of raw, freeze dried beans (Phaseolus vulgaris L., cultivar Piratã 1 with 1.394 atoms%15N, resulted in the same abundance of the whole flour and of the protein fractions extracted from the beans with 0.5 mol L-1 NaCl. The isotopic abundance found in the whole bean flour, in the protein extract, in the globulin and albumin fractions were respectively: 1.394 ± 0.011; 1.403 ± 0.012; 1.399 ± 0.007 and 1.399 ± 0.028 atoms % of 15N, presenting no difference (P > 0.05. However, a difference was found (P < 0.05 between the above mentioned abundances and the isotopic abundance found in the nitrogen of the proteins in the extraction residue, which was 0.969 ± 0.084. Since the abundances did not differ, the protein nutritive indexes, such as digestibility and biological value, determined from the nitrogen balance and corrected for isotopic dilution, would not be affected by extracting the proteins from the beans with 0.5 mol L¹ NaCl. If working with the nitrogen balance of the residual proteins after extraction and even with the whole flours, these indexes could present incorrect values, since the isotopic labelling of the residual proteins was less than that of the protein fractions.

  20. Ultratrace uranium fingerprinting with isotope selective laser ionization spectrometry.

    Ziegler, Summer L; Bushaw, Bruce A

    2008-08-01

    Uranium isotope ratios can provide source information for tracking uranium contamination in a variety of fields, ranging from occupational bioassay to monitoring aftereffects of nuclear accidents. We describe the development of isotope selective laser ionization spectrometry for ultratrace measurement of the minor isotopes (234)U, (235)U, and (236)U with respect to (238)U. The inherent isotopic selectivity of three-step excitation with single-mode continuous wave lasers results in measurement of the minor isotopes at relative abundances below 1 ppm and is not limited by isobaric interferences such as (235)UH(+) during measurement of (236)U. This relative abundance limit is attained without mass spectrometric analysis of the laser-created ions. Uranyl nitrate standards from an international blind comparison were used to test analytical performance for different isotopic compositions and with quantities ranging from 11 ng to 10 microg total uranium. Isotopic ratio determination was demonstrated over a linear dynamic range of 7 orders of magnitude with a few percent relative precision and detection limits below 500 fg for the minor isotopes. PMID:18613650

  1. Light Element Production in Solar Flares and Present Solar System Abundance of Li, Be, and B

    Bransford, M. A.; Willson, L. A.

    1998-12-01

    If production in stellar flares can be ruled out as a significant source of the Li, Be, and B isotopes observed in stellar atmospheres, then observed abundances provide very stringent constraints on stellar mass loss before and during the main sequence phase. Also, stellar surface abundances of these isotopes are often invoked as constraints on Big Bang nucleosynthesis calculations. Thus, it is important to establish reliable limits on the importance of in situ (flare) production of these isotopes. Indeed, the need for reliable limits is becoming increasingly important in light of several recent observational papers suggesting significant flare production of Li, Be, and B. The question of the possible importance of flare production of these light isotopes may be separated into two specific questions. First, can (or do) solar flares produce Li, Be, and B isotopes in the same ratios as found in the solar photosphere, taking account those slower processes that may modify the abundances ratios after they are formed? Second, are stellar flares energetically capable of producing enough Li, Be, and B to account for the observed abundances? We will present the results of calculations exploring the flare production of these light isotopes, and which address these crucial questions. How do our calculations differ from those in other investigations? The most significant difference is the choice of the mathematical form for the energy spectrum of flare accelerated particles. Calculations have previously employed a power law form, however, it has been shown that the more appropriate form is a modified Bessel function of order 2. One can derive the Bessel function solution from a Fokker-Planck equation for stochastic Fermi acceleration. The Bessel function is our adopted form for the particle energy spectrum. In order to contrast the flare production of Li, Be, B, and the ratios of the isotopes, based on the choice of the particle energy spectrum, we present calculations

  2. Organic chemistry of Murchison meteorite: Carbon isotopic fractionation

    Yuen, G. U.; Blair, N. E.; Desmarais, D. J.; Cronin, J. R.; Chang, S.

    1986-01-01

    The carbon isotopic composition of individual organic compounds of meteoritic origin remains unknown, as most reported carbon isotopic ratios are for bulk carbon or solvent extractable fractions. The researchers managed to determine the carbon isotopic ratios for individual hydrocarbons and monocarboxylic acids isolated from a Murchison sample by a freeze-thaw-ultrasonication technique. The abundances of monocarboxylic acids and saturated hydrocarbons decreased with increasing carbon number and the acids are more abundant than the hydrocarbon with the same carbon number. For both classes of compounds, the C-13 to C-12 ratios decreased with increasing carbon number in a roughly parallel manner, and each carboxylic acid exhibits a higher isotopic number than the hydrocarbon containing the same number of carbon atoms. These trends are consistent with a kinetically controlled synthesis of higher homologues for lower ones.

  3. Application of transition metal isotope tracers in global change research

    SONG Jinming; Thomas F. Pedersen

    2005-01-01

    High-precision isotope composition determinations using multicollector, magnetic-sector inductively coupled plasma mass spectrometry (MC-ICPMS) have recently revealed that some transition metal isotopes such as those of Mo, Fe, Cu, Zn etc. can be used as biogeochemical tracers in global change research.The Mo isotope system may be useful in paleoredox investigations indicating that δ 97/95Mo in seawater may co-vary with changes in the relative proportions of anoxic and oxic sedimentation in the ocean, and that this variation may be recorded in δ 97/95Mo of anoxic sediments. The Mo continental flux into the oceans and the global Mo isotope budget can be estimated fromδ 97/95MO values. The Fe isotope composition in seawater is an important issue because Fe plays a controlling role in biological productivity in the oceans and its abundance in seawater may have substantial effect on climate changes. Iron isotope fractionations could result from bio- and abio-processes and have about 0.1% variation (δ 56/54Fe), so Fe isotopes considered alone cannot be used to distinguish the products of abiotic and biotic Fe processing in geological records. Cu and Zn isotopes are also used as biogeochemical tracers, but the researches are relatively less. This review mainly focuses on the methods for preparation, purification and determination of new isotope tracer samples, and on isotope applications in marine environmental changes.

  4. Solar and Stellar Photospheric Abundances

    Prieto, Carlos Allende

    2016-01-01

    The determination of photospheric abundances in late-type stars from spectroscopic observations is a well-established field, built on solid theoretical foundations. Improving those foundations to refine the accuracy of the inferred abundances has proven challenging, but progress has been made. In parallel, developments on instrumentation, chiefly regarding multi-object spectroscopy, have been spectacular, and a number of projects are collecting large numbers of observations for stars across the Milky Way and nearby galaxies, promising important advances in our understanding of galaxy formation and evolution. After providing a brief description of the basic physics and input data involved in the analysis of stellar spectra, a review is made of the analysis steps, and the available tools to cope with large observational efforts. The paper closes with a quick overview of relevant ongoing and planned spectroscopic surveys, and highlights of recent research on photospheric abundances.

  5. Solar and stellar photospheric abundances

    Allende Prieto, Carlos

    2016-07-01

    The determination of photospheric abundances in late-type stars from spectroscopic observations is a well-established field, built on solid theoretical foundations. Improving those foundations to refine the accuracy of the inferred abundances has proven challenging, but progress has been made. In parallel, developments on instrumentation, chiefly regarding multi-object spectroscopy, have been spectacular, and a number of projects are collecting large numbers of observations for stars across the Milky Way and nearby galaxies, promising important advances in our understanding of galaxy formation and evolution. After providing a brief description of the basic physics and input data involved in the analysis of stellar spectra, a review is made of the analysis steps, and the available tools to cope with large observational efforts. The paper closes with a quick overview of relevant ongoing and planned spectroscopic surveys, and highlights of recent research on photospheric abundances.

  6. Perchlorate in The Great Lakes: Isotopic Composition and Origin

    Poghosyan, Armen; Sturchio, Neil C.; Morrison, Candice G.; Beloso, Abelardo D., Jr.; Guan, Yunbin; Eiler, John M.; Jackson, W. Andrew; Hatzinger, Paul B.

    2014-01-01

    Perchlorate is a persistent and mobile contaminant in the environment with both natural and anthropogenic sources. Stable isotope ratios of oxygen (δ^(18)O, Δ^(17)O) and chlorine (δ^(37)Cl) along with the abundance of the radioactive isotope ^(36)Cl were used to trace perchlorate sources and behavior in the Laurentian Great Lakes. These lakes were selected for study as a likely repository of recent atmospheric perchlorate deposition. Perchlorate concentrations in the Great Lakes range from 0....

  7. Isotopic Anomalies in CP Stars: Helium, Mercury, Platinum, and Calcium

    Cowley, C R; Castelli, F

    2007-01-01

    We review the classical observational results for isotopic abundance variations for several elements in CP stars. We concentrate on the "newest" anomaly, in calcium. The cosmically very rare isotope, Ca-48 can rival and even dominate the more common, alpha nuclide, Ca-40. Relevant examples are found in the hot, non-magnetic HgMn stars, and the field horizontal-branch star, Feige 86. The calcium anomaly is also present in cool, magnetic stars, including the notorious HD 101065, Przybylski's star.

  8. Determination of zinc stable isotopes in biological materials using isotope dilution inductively coupled plasma mass spectrometry

    A method is described for using isotope dilution to determine both the amount of natural zinc and enriched isotopes of zinc in biological samples. Isotope dilution inductively coupled plasma mass spectrometry offers a way to quantify not only the natural zinc found in a sample but also the enriched isotope tracers of zinc. Accurate values for the enriched isotopes and natural zinc are obtained by adjusting the mass count rate data for measurable instrumental biases. Analytical interferences from the matrix are avoided by extracting the zinc from the sample matrix using diethylammonium diethyldithiocarbamate. The extraction technique separates the zinc from elements which form interfering molecular ions at the same nominal masses as the zinc isotopes. Accuracy of the method is verified using standard reference materials. The detection limit is 0.06 μg Zn per sample. Precision of the abundance ratios range from 0.3-0.8%. R.S.D. for natural zinc concentrations is about 200-600 μg g-1. The accuracy and precision of the measurements make it possible to follow enriched isotopic tracers of zinc in biological samples in metabolic tracer studies. (author). 19 refs.; 1 fig., 4 tabs

  9. Boron-isotope fractionation in plants

    Naturally-occurring variations in the abundance of stable isotopes of carbon, nitrogen, oxygen, and other elements in plants have been reported and are now used to understand various physiological processes in plants. Boron (B) isotopic variation in several plant species have been documented, but no determination as to whether plants fractionate the stable isotopes of boron, 11B and 10B, has been made. Here, we report that plants with differing B requirements (wheat, corn and broccoli) fractionated boron. The whole plant was enriched in 11B relative to the nutrient solution, and the leaves were enriched in 10B and the stem in 11B relative to the xylem sap. Although at present, a mechanistic role for boron in plants is uncertain, potential fractionating mechanisms are discussed. (author)

  10. Steelhead Abundance - Point Features [ds184

    California Department of Resources — The CalFish Abundance Database contains a comprehensive collection of anadromous fisheries abundance information. Beginning in 1998, the Pacific States Marine...

  11. Coho Abundance - Point Features [ds182

    California Department of Resources — The CalFish Abundance Database contains a comprehensive collection of anadromous fisheries abundance information. Beginning in 1998, the Pacific States Marine...

  12. Coho Abundance - Linear Features [ds183

    California Department of Resources — The CalFish Abundance Database contains a comprehensive collection of anadromous fisheries abundance information. Beginning in 1998, the Pacific States Marine...

  13. Chinook Abundance - Point Features [ds180

    California Department of Resources — The CalFish Abundance Database contains a comprehensive collection of anadromous fisheries abundance information. Beginning in 1998, the Pacific States Marine...

  14. Steelhead Abundance - Linear Features [ds185

    California Department of Resources — The CalFish Abundance Database contains a comprehensive collection of anadromous fisheries abundance information. Beginning in 1998, the Pacific States Marine...

  15. Hf Transition Probabilities and Abundances

    Lawler, J E; Labby, Z E; Sneden, C; Cowan, J J; Ivans, I I

    2006-01-01

    Radiative lifetimes from laser-induced fluorescence measurements, accurate to about +/- 5 percent, are reported for 41 odd-parity levels of Hf II. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 150 lines of Hf II. Approximately half of these new transition probabilities overlap with recent independent measurements using a similar approach. The two sets of measurements are found to be in good agreement for measurements in common. Our new laboratory data are applied to refine the hafnium photospheric solar abundance and to determine hafnium abundances in 10 metal-poor giant stars with enhanced r-process abundances. For the Sun we derive log epsilon (Hf) = 0.88 +/- 0.08 from four lines; the uncertainty is dominated by the weakness of the lines and their blending by other spectral features. Within the uncertainties of our analysis, the r-process-rich stars possess constant Hf/La and Hf/Eu abundance ratios, log epsilon (Hf...

  16. Gd Transition Probabilities and Abundances

    Den Hartog, E A; Sneden, C; Cowan, J J

    2006-01-01

    Radiative lifetimes, accurate to +/- 5%, have been measured for 49 even-parity and 14 odd-parity levels of Gd II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 611 lines of Gd II. This work is the largest-scale laboratory study to date of Gd II transition probabilities and the first using a high performance Fourier transform spectrometer. This improved data set has been used to determine a new solar photospheric Gd abundance, log epsilon = 1.11 +/- 0.03. Revised Gd abundances have also been derived for the r-process-rich metal-poor giant stars CS 22892-052, BD+17 3248, and HD 115444. The resulting Gd/Eu abundance ratios are in very good agreement with the solar-system r-process ratio. We have employed the increasingly accurate stellar abundance determinations, resulting in large part from the more precise laboratory atomic data, to predict directly the Solar System r-process elemental...

  17. Isotopic geology; Geologie isotopique

    Allegre, C. [Paris-7 Univ. Denis Diderot, 75 (France); Institut de physique du globe de Paris, 75 - Paris (France)

    2005-07-01

    Born from the application to geology of nuclear physics techniques, the isotopic geology has revolutionized the Earth's sciences. Beyond the dating of rocks, the tracer techniques have permitted to reconstruct the Earth's dynamics, to measure the temperatures of the past (giving birth to paleoclimatology) and to understand the history of chemical elements thanks to the analysis of meteorites. Today, all domains of Earth sciences appeal more or less to the methods of isotopic geology. In this book, the author explains the principles, methods and recent advances of this science: 1 - isotopes and radioactivity; 2 - principles of isotope dating; 3 - radio-chronological methods; 4 - cosmogenic isotope chronologies; 5 - uncertainties and radio-chronological results; 6 - geochemistry of radiogenic isotopes; 7 - geochemistry of stable isotopes; 8 - isotopic geology and dynamical analysis of reservoirs. (J.S.)

  18. Abundance estimation and Conservation Biology

    Nichols, J. D.

    2004-06-01

    Full Text Available Abundance is the state variable of interest in most population–level ecological research and in most programs involving management and conservation of animal populations. Abundance is the single parameter of interest in capture–recapture models for closed populations (e.g., Darroch, 1958; Otis et al., 1978; Chao, 2001. The initial capture–recapture models developed for partially (Darroch, 1959 and completely (Jolly, 1965; Seber, 1965 open populations represented efforts to relax the restrictive assumption of population closure for the purpose of estimating abundance. Subsequent emphases in capture–recapture work were on survival rate estimation in the 1970’s and 1980’s (e.g., Burnham et al., 1987; Lebreton et al.,1992, and on movement estimation in the 1990’s (Brownie et al., 1993; Schwarz et al., 1993. However, from the mid–1990’s until the present time, capture–recapture investigators have expressed a renewed interest in abundance and related parameters (Pradel, 1996; Schwarz & Arnason, 1996; Schwarz, 2001. The focus of this session was abundance, and presentations covered topics ranging from estimation of abundance and rate of change in abundance, to inferences about the demographic processes underlying changes in abundance, to occupancy as a surrogate of abundance. The plenary paper by Link & Barker (2004 is provocative and very interesting, and it contains a number of important messages and suggestions. Link & Barker (2004 emphasize that the increasing complexity of capture–recapture models has resulted in large numbers of parameters and that a challenge to ecologists is to extract ecological signals from this complexity. They offer hierarchical models as a natural approach to inference in which traditional parameters are viewed as realizations of stochastic processes. These processes are governed by hyperparameters, and the inferential approach focuses on these hyperparameters. Link & Barker (2004 also suggest that

  19. Optical isotope shifts for unstable samarium isotopes

    Using a tunable dye laser beam intersecting a thermal atomic beam, optical isotope shifts and hyperfine splittings have been measured for the four unstable samarium isotopes between 144Sm and 154Sm, covering the well known transition region from spherical to deformed shapes. (orig.)

  20. Rapid photochemical equilibration of isotope bond ordering in O2

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

    2014-09-01

    The abundances of 18O18O and 17O18O in the atmosphere were recently found to be enriched relative to the stochastic distribution of isotopes in O2. The enrichment is believed to arise from O(3P) + O2 isotope exchange reactions, which reorder the isotopes in O2 to a distribution that favors bonds between heavy isotopes. Theoretical predictions and laboratory experiments suggest that the reordered distribution of isotopes should reflect internal isotopic equilibrium, but a laboratory test of this hypothesis for the complete O2 isotopologue system has not yet been realized. Here we use a simple photochemical experiment that reorders the isotopes in O2 at temperatures between 200 K and 350 K. Using simultaneous measurements of five O2 isotopologues, we show that O(3P) + O2 reorders the isotopes in O2 to isotopic equilibrium. Furthermore, we use this scheme to calibrate measurements of isotopic ordering in samples of O2, obtaining Δ36 and Δ35 values within ±0.1‰. Measurements of atmospheric O2 sampled at the University of California, Los Angeles, from 2012 to 2014 have mean values of Δ36 = 1.97 ± 0.07‰ and Δ35 = 1.0 ± 0.1‰ (2 SE; n = 23), with no detectable long-term trend. These measurements are consistent with values for air reported earlier, but with a threefold to fourfold improvement in precision. Together, the experiments and observations support the case that isotopic ordering in tropospheric O2 is altered by O(3P) + O2; however, they also suggest that tropospheric Δ36 and Δ35 values do not reflect complete isotopic equilibration in the troposphere. Isotopic ordering in atmospheric O2 likely reflects the decadal-scale balance of stratospheric and tropospheric air masses modulated by variations in tropospheric photochemistry and convection.

  1. Generating potassium abundance variations in the Solar Nebula

    Hubbard, Alexander

    2016-04-01

    An intriguing aspect of chondritic meteorites is that they are complementary: while their separate components have wildly varying abundances, bulk chondrites have nearly solar composition. This implies that the nearly-solar reservoirs in which chondrites were born were in turn assembled from sub-reservoirs of differing compositions that birthed the different components. We focus on explaining the potassium abundance variations between chondrules even within a single chondrite, while maintaining the observed CI 41K to 39K ratios. This requires physically separating potassium and chondrules while the temperature is high enough for K to be in the gas phase. We examine several mechanisms which could drive the dust through gas and show that to do so locally would have required long (sub-orbital to many orbits) time scales; with shortest potassium depletion time scales occurring in a scenario where chondrules formed high above the midplane and settled out of the evaporated potassium. While orbital time scales are at odds with laboratory chondrule cooling rate estimates, any other model for the origin for the potassium abundance variation has to wrestle with the severe logistical difficulty of generating a plethora of correlated reservoirs which varied strongly in their potassium abundances, but not in their potassium isotope ratios.

  2. Generating potassium abundance variations in the Solar Nebula

    Hubbard, Alexander

    2016-08-01

    An intriguing aspect of chondritic meteorites is that they are complementary: while their separate components have wildly varying abundances, bulk chondrites have nearly solar composition. This implies that the nearly solar reservoirs in which chondrites were born were in turn assembled from sub-reservoirs of differing compositions that birthed the different components. We focus on explaining the potassium abundance variations between chondrules even within a single chondrite, while maintaining the observed CI 41K to 39K ratios. This requires physically separating potassium and chondrules while the temperature is high enough for K to be in the gas phase. We examine several mechanisms which could drive the dust through gas and show that to do so locally would have required long (sub-orbital to many orbits) time scales; with shortest potassium depletion time-scales occurring in a scenario where chondrules formed high above the mid-plane and settled out of the evaporated potassium. While orbital time-scales are at odds with laboratory chondrule cooling rate estimates, any other model for the origin for the potassium abundance variation has to wrestle with the severe logistical difficulty of generating a plethora of correlated reservoirs which varied strongly in their potassium abundances, but not in their potassium isotope ratios.

  3. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems.

    Lepoint, Gilles; Dauby, Patrick; Gobert, Sylvie

    2004-12-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure of trophic webs in temperate, Mediterranean and tropical seagrass ecosystems. As environmental tracers, stable isotopes have proven their utility in sewage impact measuring and mapping. However, to make such environmental studies more comprehensible, future works on understanding of basic reasons for variations of N and C stable isotopes in seagrasses should be encouraged. At least, as experimental tracers, stable isotopes allow the study of many aspects of N and C cycles at the scale of a plant or at the scale of the seagrass ecosystem. PMID:15556172

  4. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems

    Lepoint, Gilles [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium)]. E-mail: g.lepoint@ulg.ac.be; Dauby, Patrick [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium); Institut Royal des Sciences Naturelles de Belgique, rue Vautier, B1000 Brussels (Belgium); Gobert, Sylvie [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium)

    2004-12-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure of trophic webs in temperate, Mediterranean and tropical seagrass ecosystems. As environmental tracers, stable isotopes have proven their utility in sewage impact measuring and mapping. However, to make such environmental studies more comprehensible, future works on understanding of basic reasons for variations of N and C stable isotopes in seagrasses should be encouraged. At least, as experimental tracers, stable isotopes allow the study of many aspects of N and C cycles at the scale of a plant or at the scale of the seagrass ecosystem.

  5. The chlorine isotope fingerprint of the lunar magma ocean

    Boyce, Jeremy W.; Treiman, Allan H.; Guan, Yunbin; Ma, Chi; Eiler, John M.; Gross, Juliane; Greenwood, James P.; Stolper, Edward M.

    2015-01-01

    The Moon contains chlorine that is isotopically unlike that of any other body yet studied in the Solar System, an observation that has been interpreted to support traditional models of the formation of a nominally hydrogen-free (“dry”) Moon. We have analyzed abundances and isotopic compositions of Cl and H in lunar mare basalts, and find little evidence that anhydrous lava outgassing was important in generating chlorine isotope anomalies, because ^(37)Cl/^(35)Cl ratios are not related to Cl a...

  6. Statistical clumped isotope signatures.

    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 molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  7. Sm Transition Probabilities and Abundances

    Lawler, J E; Sneden, C; Cowan, J J

    2005-01-01

    Radiative lifetimes, accurate to +/- 5%, have been measured for 212 odd-parity levels of Sm II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier-transform spectrometry to determine transition probabilities for more than 900 lines of Sm II. This work is the largest-scale laboratory study to date of Sm II transition probabilities using modern methods. This improved data set has been used to determine a new solar photospheric Sm abundance, log epsilon = 1.00 +/- 0.03, from 26 lines. The spectra of three very metal-poor, neutron-capture-rich stars also have been analyzed, employing between 55 and 72 Sm II lines per star. The abundance ratios of Sm relative to other rare earth elements in these stars are in agreement, and are consistent with ratios expected from rapid neutron-capture nucleosynthesis (the r-process).

  8. Molecular Paleohydrology: Interpreting the Hydrogen- Isotopic Composition of Lipid Biomarkers from Photosynthesizing Organisms

    Sachse, D.; Billault, I.; Bowen, G.J.; Chikaraishi, Y.; Dawson, T.E.; Feakins, S.J.; Freeman, Katherine; Magill, C.R.; McInerney, F.A.; van der Meer, M.T.J.; Polissar, P.; Robins, R.J.; Sachs, J.P.; Schmidt, H.L.; Sessions, A.L.; White, J.W.C.; West, J.B.; Kahmen, A.

    2012-01-01

    Hydrogen-isotopic abundances of lipid biomarkers are emerging as important proxies in the study of ancient environments and ecosystems. A decade ago, pioneering studies made use of new analytical methods and demonstrated that the hydrogen-isotopic composition of individual lipids from aquatic and te

  9. Static, Mixed-Array Total Evaporation for Improved Quantitation of Plutonium Minor Isotopes in Small Samples

    Stanley, F. E.; Byerly, Benjamin L.; Thomas, Mariam R.; Spencer, Khalil J.

    2016-03-01

    Actinide isotope measurements are a critical signature capability in the modern nuclear forensics "toolbox", especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (CRM-126a, and compared with traditional total evaporation methods.

  10. Static, Mixed-Array Total Evaporation for Improved Quantitation of Plutonium Minor Isotopes in Small Samples

    Stanley, F. E.; Byerly, Benjamin L.; Thomas, Mariam R.; Spencer, Khalil J.

    2016-06-01

    Actinide isotope measurements are a critical signature capability in the modern nuclear forensics "toolbox", especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (CRM-126a, and compared with traditional total evaporation methods.

  11. Environmental isotope investigation of groundwater flow in the Honey Lake Basin, California and Nevada

    Rose, T.P.; Davisson, M.L.; Hudson, G.B.; Varian, A.R.

    1997-07-01

    The hydrology of Honey Lake Basin was studied using environmental isotope measurements of approximately 130 water samples collected during 1995 and 1996. The principal analytical methods included hydrogen, oxygen and carbon stable isotope ratio measurements, radiocarbon and tritium dating, and measurements of dissolved noble gas abundances.

  12. Isotope fractionation of selenium by biomethylation in microcosm incubations of soil

    Schilling, K.; Johnson, T.M.; Wilcke, W.

    2013-01-01

    The natural abundance of stable Se isotopes in methylselenides reflects sources and formation conditions of methylselenides. We tested the effects of (i) different inorganic Se species spiked to soils and (ii) different soil samples on the extent of fungal biomethylation of Se and the Se isotope rat

  13. Abundances in stars with exoplanets

    Israelian, Garik

    2003-01-01

    Extensive spectroscopic studies of stars with and without planets have concluded that stars hosting planets are significantly more metal-rich than those without planets. More subtle trends of different chemical elements begin to appear as the number of detected extrasolar planetary systems continues to grow. I review our current knowledge concerning the observed abundance trends of various chemical elements in stars with exoplanets and their possible implications.

  14. Isotopes in heterogeneous catalysis

    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. Oxygen Gas Phase Abundance Revisited

    André, M K; Howk, J C; Ferlet, R; Désert, J M; Hébrard, G; Lacour, S; Lecavelier-des-Etangs, A; Vidal-Madjar, A; Moos, H W

    2003-01-01

    We present new measurements of the interstellar gas-phase oxygen abundance along the sight lines towards 19 early-type galactic stars at an average distance of 2.6 kpc. We derive O {\\small I} column densities from {\\it HST}/STIS observations of the weak 1355 \\AA intersystem transition. We derive total hydrogen column densities [N(H {\\small I})+2N(H$_2$)] using {\\it HST}/STIS observations of \\lya and {\\it FUSE} observations of molecular hydrogen. The molecular hydrogen content of these sight lines ranges from f(H$_2$) = 2N(H$_2$)/[N(H {\\small I})+2N(H$_2$)] = 0.03 to 0.47. The average $$ of 6.3$\\times10^{21}$ cm$^{-2}$ mag$^{-1}$ with a standard deviation of 15% is consistent with previous surveys. The mean oxygen abundance along these sight lines, which probe a wide range of galactic environments in the distant ISM, is 10$^6$ \\oh = $408 \\pm 13$ (1 $\\sigma$ in the mean). %$({\\rm O/H})_{gas} = 408 \\pm 14$(1 $\\sigma$). We see no evidence for decreasing gas-phase oxygen abundance with increasing molecular hydroge...

  16. On the isotope ratio of hydrogen, oxygen, carbon, nitrogen, and sulfur in man

    Experimental investigations of the isotope ratio of hydrogen, oxygen, carbon, nitrogen and sulfur in urine of persons living at different locations show considerable variations. A distinct relation to the isotope ratio of the local drinking water has only been observed in the case of hydrogen. The variations are far from being within the experimental limits of error. Therefore, they are decisive in selecting the relative abundance of the labelling isotope in tracer experiments on human metabolism. (author)

  17. Planetary nebulae abundances and stellar evolution

    Pottasch, S. R.; Bernard-Salas, J.

    2006-01-01

    A summary is given of planetary nebulae abundances from ISO measurements. It is shown that these nebulae show abundance gradients (with galactocentric distance), which in the case of neon, argon, sulfur and oxygen (with four exceptions) are the same as HII regions and early type star abundance gradients. The abundance of these elements predicted from these gradients at the distance of the Sun from the center are exactly the solar abundance. Sulfur is the exception to this; the reason for this...

  18. Stable isotope applications

    The following domains of stable isotope applications are presented: - isotope dilution analyses as in trace analyses or volume and mass determinations; - stable isotopes as tracers as applied in environmental studies, agricultural research, products and objects authentification, transport phenomena, reaction mechanisms, determinations of structure and complex biological function, metabolism studies, diagnostic respiration tests, positron emission tomography; - equilibrium isotopic effects as investigated in measurements of effects, studies of equilibrium conditions, the mechanism of drug action, study of natural processes, water circuit, temperature measurements; - kinetic isotopic effects, as, for instance, reaction rates and mechanisms, solvent isotopic effects; - stable isotopes for advanced nuclear reactors as, for instance, uranium nitride with 15 N as nuclear fuel or 157 Gd for reactivity control. In spite of the difficulties regarding stable isotope use and first of all, of the difficult and costly analytical techniques, a continuous growth of the number of stable isotope applications in different fields is registered. The number of works and scientific meetings on the subject, as organized by the International Society of Isotopes and IAEA-Vienna, Gordon Conferences, regional meetings in Germany, France, etc. increase continuously. Development of the stable isotope application on a larger scale requires improving both their production technologies as well as those of labelled substances and, at the same time, the analytical methods

  19. Chromium isotope variations

    D'Arcy, Joan Mary

    Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. For this reason the Cr isotope system is being developed as a potential tool for paleo-redox reconstruction. Dissolved Cr in seawater...... 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......, 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...

  20. Enrichment of Gadolinium isotope: column chromatography study

    Naturally occurring Gadolinium consists of 7 stable isotopes. 152Gd, 154 Gd, 155Gd 156Gd, 157Gd, 158Gd and 160Gd of which abundance ratios are 0.20, 2.18, 14.80, 20.47, 15.65, 24.84 and 21.86% respectively. Gd has the highest cross section for the capture of thermal neutrons of any element due to the high cross section of 157Gd (254,000 barn) and 155Gd (60,900 barn). All the remaining isotopes are having lower values (1.4-735 barn). Gd is used as a burnable poison in nuclear fuel, but the use of 155/157Gd would create an even more effective burnable poison. Gd isotope separation by displacement chromatography was performed in cation exchange resin. Column experiments were performed using 3 jacketed glass columns in series (10 mm dia and 1m length) packed with Dowex 50X8 of bed height of 90 cm. Initially the bed was converted to Cu2+ form. Then 50 cm Gd3+ band was formed using Gd (NO3)3 solution. The band was displaced using (NH4)4-EDTA +NH4NO3 ) solution. The sample was eluted after different migration length of Gd band. The mass spectrometric analysis using TIMS and ICP-MS was performed to measure the enrichment of Gd isotope and the results are found to be encouraging. In the case of natural Gd, the 157/160Gd ratio was found to be 0.7396. The isotopic ratio in the front end was gone down to 0.7077 and in the rear end the value was gone up to 0.7446 which indicates that the front end band is enriched with heavier isotope and rear end is enriched with lighter isotope. Further computational and experimental studies are underway

  1. Performance of isotope correlations for the estimate of 242Pu

    The lack of a gamma-ray signature from 242 Pu represents an Achilles heel for many plutonium isotope abundance measurements made by high-resolution gamma spectrometry (HRGS). This holds in particular for plutonium materials containing a significant fraction of this isotope. The problem is partially solved through the application of isotope correlations estimating the relative abundance of 242 Pu from relations to ratios of other plutonium isotopes measurable by HRGS. In the mid of the nineties a new type of isotope correlation had been proposed for LWR plutonium with the recommended coefficients for PWR and BWR fuels. This type of correlation was adopted for the routine analysis of safeguards samples in the Euratom On-Site Laboratories and in the Institute for Transuranium Elements. In order to cover the full range of plutonium materials received for analysis, the application of the above correlation has been also extended to AGR and Magnox-type of plutonium with different sets of coefficients approximating best the correlation for the additional types of materials were determined from a set of reference isotopic data. Since in many instances the origin and the type of the plutonium are not known a priori, criteria for categorization were established helping to select the appropriate isotope correlation. Parametric plots of the ratios 238 Pu/239 Pu versus 240 Pu/239 Pu generally allow to discern unambiguously Magnox, AGR and LWR plutonium, and to some extent also BWR and PWR plutonium, as long as a mixing of the respective plutonium materials has not occurred. With this kind of categorization implemented in the routine analysis the performance of the 242 Pu estimate is substantially improving in most cases. Performance data for 242 Pu in particular, and for plutonium isotope abundance measurements by HRGS in general, as derived from a larger set of measurement data are presented and discussed in terms of their impact on the interpretation of passive neutron

  2. Lead abundance in the uranium star CS 31082-001

    Plez, B.; Hill, V.; Cayrel, R.; Spite, M.; Barbuy, B.; Beers, T.C.; Bonifacio, P.; Primas, F.; Nordström, B.

    2004-01-01

    stars:abundances- physical data and processes: nuclear reactions, nucleosynthesis, abundances- atomic data......stars:abundances- physical data and processes: nuclear reactions, nucleosynthesis, abundances- atomic data...

  3. Isotopic contamination in electromagnetic isotope separators

    The mechanisms producing isotopic contamination in the electromagnetic separation of isotopes are studied with the aid of the Separator of Saclay and an electrostatic analyzer in cascade. After a separate investigation the result of which is that no contamination comes from the spreading of initial energies of ions, two principal mechanisms are emphasized; scattering and instability of the regime of the sources. The characters of each type of contamination arising from both mechanisms are described in some detail. An unique scheme of isotopic contamination is then derived from the partial ones. This scheme is successfully verified in several experimental separations. The applications concern principally the performances of magnetic cascades and more complex apparatus. It is found that the isotopic purities that such machines can deliver are extremely high. (author)

  4. Selenium speciation and isotope composition in 77Se-enriched yeast using gradient elution HPLC separation and ICP-dynamic reaction cell-MS

    Larsen, Erik Huusfeldt; Sloth, Jens Jørgen; Hansen, M.;

    2003-01-01

    A batch of Se-77-labelled and enriched yeast was characterised with regard to isotopic composition and content of selenium species for later use in a human absorption study based on the method of enriched stable isotopes. The abundance of the six stable selenium isotopes was determined by ICP- MS...... equipped with a dynamic reaction cell (DRC). The results showed that the Se-77 isotope was enriched to 98.5 atom-%, whereas the remaining selenium was present as the other five isotopes at low abundance. The low-molecular Se-77 containing species, which were biosynthesised by the yeast during fermentation...

  5. Mass spectrometric study of the mercury isotopes in the Allende meteorite

    Nier, A. O.; Schlutter, D. J.

    1986-01-01

    Isotopic abundance ratios for mercury were determined by mass spectrometry in six samples of bulk material and in one sample of chondrules from the Allende meteorite. A primary purpose of the work was to attempt to verify the anomalous ratios reported for Hg-196/Hg-202 by neutron activation. Measurements were made on the mercury released at temperatures of 250, 450, 600 C, and in some cases, higher temperatures. The precision of the measurements was such that if an anomaly of the magnitude reported exists, it should have been seen. The isotopic abundance ratios for the other mercury isotopes were also measured. Within the errors of measurement these agreed with normal terrestrial values.

  6. MULTIPLE ORIGINS OF NITROGEN ISOTOPIC ANOMALIES IN METEORITES AND COMETS

    Isotopic fractionation and mixing calculations compared with coupled hydrogen and nitrogen isotopic composition of organic molecules from primitive chondrites, interplanetary dust particles (IDPs), and comets C/1995 O1 (Hale-Bopp) and 81P/Wild2 reveal that meteoritic and cometary organic matter contains three different isotopic components of different origins. (1) A major component of carbonaceous chondrites, IDPs, and comets Hale-Bopp and Wild2 shows correlated H and N isotopic compositions attributable to isotope exchange between an organic matter of solar composition and a reservoir formed by ion-molecule reactions at T 15N-rich component having identical 15N and D enrichments relative to the protosolar gas. Temperatures > 100 K deduced from the low D/H ratio and an anti-correlation between the abundance of this component and meteoritic age indicate a late origin in the solar protoplanetary disk. N2 self-shielding and the non-thermal nucleosynthesis of 15N upon irradiation are possible but unlikely sources of this component, and a chemical origin is preferred. (3) An interstellar component with highly fractionated hydrogen isotopes and unfractionated nitrogen isotopes is present in ordinary chondrites. A dominantly solar origin of D and 15N excesses in primitive solar system bodies shows that isotopic anomalies do not necessarily fingerprint an interstellar origin and implies that only a very small fraction of volatile interstellar matter survived the events of solar system formation.

  7. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeolimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteroic waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author). 56 refs., 11 figs., 2 tabs.

  8. Stable isotope geochemistry: definitions, terminology, measurement and some applications

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeoclimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteoric waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author).

  9. Isotope enrichment systems

    This invention provides a system in which both phases of the countercurrent contact isotope exchange concentration process are recycled continuously and an isotope depleted liquid phase substance thereof has its prior content of the desired isotope of hydrogen and/or oxygen replenished in an isotope regenerator by direct contact isotope exchange with a flow of steam from a source external to the concentrating process, whereby such replenished liquid serves as the feed liquid for the concentration process. As the supply of steam is gaseous, all problems incident to mineral solids in solution in liquid water are eliminated. As the elevated temperature corresponds to that of the steam, the isotope replenishment of the process feed liquid may be conducted without materially altering the characteristics of the steam for use as an energy source in any system

  10. Uses of stable isotopes

    The most important fields of stable isotope use with examples are presented. In isotope dilution analysis the stable isotopes are used in trace analysis, measurements of volumes and masses. In the field of stable isotope use as tracers the following applications are encountered: transport phenomena, environmental studies, agricultural research, authentication of products and objects, archaeometry, studies of reaction mechanisms, structure and function determination of complex biological entities, studies of metabolism, breath test for diagnostic. In the domain of isotope equilibrium effects applications in the study of mechanism of drug action, study of natural processes, investigation of equilibrium conditions and water cycle as well as in temperature measurements are encountered. Stable isotopes are also used in advanced nuclear reactors, particularly, the uranium nitride with 15 N as nuclear fuel and 157 Gd for reactor control. In spite of some difficulties of stable isotope use, especially related to analytical techniques, which are slow and expensive, the number of papers reporting this subject is steadily growing as well the number of scientific meetings organized by International Isotope Society and IAEA, Gordon Conferences, and regional meetings in Germany, France, etc. Stable isotope application development on large scale is ensured by improving their production technologies, as well as by development of new labelled compounds and of analytical techniques. (author)

  11. Isotopes in hydrogeology

    Questions of the application of radioactive isotopes in hydrogeology and seismology are considered, as well as their physico-chemical and geochemical properties and the regularities of their occurrence and migration in natural waters. The possibility of application of these isotopes in calculating the age of waters and in solving paleohydrogeological problems is studied. Elucidated are questions of utilization of helium and uranium isotope content in determining the effect of faults on the hydrogeological conditions of regions and in selecting burial sites for industrial wastes. Utilization of changes in the isotopic and gas composition of underground waters during the activization of tectonic movements for earthquake forecasts is considered

  12. PRINCIPAL ISOTOPE SELECTION REPORT

    Utilizing nuclear fuel to produce power in commercial reactors results in the production of hundreds of fission product and transuranic isotopes in the spent nuclear fuel (SNF). When the SNF is disposed of in a repository, the criticality analyses could consider all of the isotopes, some principal isotopes affecting criticality, or none of the isotopes, other than the initial loading. The selected set of principal isotopes will be the ones used in criticality analyses of the SNF to evaluate the reactivity of the fuel/waste package composition and configuration. This technical document discusses the process used to select the principal isotopes and the possible affect that these isotopes could have on criticality in the SNF. The objective of this technical document is to discuss the process used to select the principal isotopes for disposal criticality evaluations with commercial SNF. The principal isotopes will be used as supporting information in the ''Disposal Criticality Analysis Methodology Topical Report'' which will be presented to the United States Nuclear Regulatory Commission (NRC) when approved by the United States Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM)

  13. The isotope breathe test

    The foundations of the breath diagnostic test, based on application of the carbon compounds, labeled with the stable (13C) or radioactive isotope are presented. The methodology for conducting the breath isotope test and the apparatuses, making it possible to determine under clinical conditions the isotope composition of the carbon, contained in the expired air, depending on the introduced tracer type, is briefly described. The safety of the method and prospects of its application are discussed. The examples of the breath isotope test practical application are presented

  14. Krypton isotope analysis using near-resonant stimulated Raman spectroscopy

    A method for measuring low relative abundances of 85Kr in one liter or less samples of air has been under development here at Pacific Northwest Laboratory. The goal of the Krypton Isotope Laser Analysis (KILA) method is to measure ratios of 10-10 or less of 85Kr to more abundant stable krypton. Mass spectrometry and beta counting are the main competing technologies used in rare-gas trace analysis and are limited in application by such factors as sample size, counting times, and selectivity. The use of high-resolution lasers to probe hyperfine levels to determine isotopic abundance has received much attention recently. In this study, we report our progress on identifying and implementing techniques for trace 85Kr analysis on small gas samples in a static cell as well as limitations on sensitivity and selectivity for the technique. High-resolution pulsed and cw lasers are employed in a laser-induced fluorescence technique that preserves the original sample. This technique, is based on resonant isotopic depletion spectroscopy (RIDS) in which one isotope is optically depleted while preserving the population of a less abundant isotope. The KILA method consists of three steps. In the first step, the 1s5 metastable level of krypton is populated via radiative cascade following two-photon excitation of the 2p6 energy level. Next, using RBDS, the stable krypton isotopes are optically depleted to the ground state through the 1s4 level with the bulk of the 85Kr population being preserved. Finally, the remaining metastable population is probed to determine 85Kr concentration. The experimental requirements for each of these steps are outlined below

  15. A note on the abundance conjecture

    Dorsch, Tobias; Lazić, Vladimir

    2014-01-01

    We prove that the abundance conjecture for non-uniruled klt pairs in dimension $n$ implies the abundance conjecture for uniruled klt pairs in dimension $n$, assuming the Minimal Model Program in lower dimensions.

  16. Making an honest measurement scale out of the oxygen isotope delta-values.

    Gat, Joel R; DeBievre, Paul

    2002-01-01

    The differential measurement of the abundance of oxygen isotopes based on reference materials, such as VSMOW for the case of water, was used because the precision of the absolute mass-spectrometric determination of the abundance fell short of the differences to be measured. Since then these measurements have been much improved, so that a calibration scheme of the oxygen isotope abundance in water, carbonates, silica, phosphates, sulfates, nitrates and organic materials is suggested, based on an accredited primary standard of oxygen in air and using standard fluorination and O(2) to CO(2) conversion techniques. PMID:12442297

  17. Solar System chemical abundances corrected for systematics

    Gonzalez, Guillermo

    2014-01-01

    The relative chemical abundances between CI meteorites and the solar photosphere exhibit a significant trend with condensation temperature. A trend with condensation temperature is also seen when the solar photospheric abundances are compared to those of nearby solar twins. We use both these trends to determine the alteration of the elemental abundances of the meteorties and the photosphere by fractionation and calculate a new set of primordial Solar System abundances.

  18. Isotope analysis by infrared laser absorption spectroscopy

    The feasibility of IR laser spectroscopy as a technique for the measurement of small abundances of stable and radioactive isotopes has been examined. Theoretical considerations and first experimental results with two laser systems are presented: 1) Coincidences between emission lines of a CO2-laser and absorption lines of 13C-subsituted ethylene can be used to determine the 13C-concentration of C2H4. 2) A tunable PbS-diode laser emitting in the 4.3 μm-spectral region of the rotation-vibration bands of CO2 can be used to determine abundances of 12C, 13C, 16O, 17O and 18O in small samples of CO2. With optimized performance, sensitivities up to 10-9-10-10 seem possible, and for higher abundances an accuracy of 10-3. This should allow geophysical isotope studies to be performed and it is hoped that the technique will eventually be applicable to measuring the activity of long-lived radioisotopes. (orig.)

  19. The Relic Abundance of Massive Colored Particles after a Late Hadronic Annihilation Stage

    Jacoby, Chen

    2007-01-01

    We discuss the relic abundance of massive long lived colored particles with mass of the order of 1 TeV. We first examine the case where the massive colored particles have the standard color only. Next we consider the "Quirk Model" suggested by M. Luty, in which the colored particles transform under an additional non-abelian gauge group with a scale much smaller than the particles' mass. In both cases, the relic abundance is reduced via a "late" hadronic annihilation stage. In the second case the relic Quirks bind to ordinary quarks forming fractional charged objects and also anomalous heavy isotopes, and the bounds on the relic abundance become extremely severe. The force between Quirks, however, has a new confining part that manifests via macroscopic strings and the resulting efficient "very late" annihilations reduce the relic abundance to acceptable levels. The prospects of creating and detecting such particles at LHC and the fate of the particles created are discussed.

  20. Intracellular Cadmium Isotope Fractionation

    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.

  1. Isotope pattern deconvolution as a tool to study iron metabolism in plants

    Rodriguez-Castrillon, Jose A.; Moldovan, Mariella; Garcia Alonso, J.I. [University of Oviedo, Department of Physical and Analytical Chemistry, Oviedo (Spain); Lucena, Juan J.; Garcia-Tome, Maria L.; Hernandez-Apaolaza, Lourdes [Autonoma University of Madrid, Department of Agricultural Chemistry, Madrid (Spain)

    2008-01-15

    Isotope pattern deconvolution is a mathematical technique for isolating distinct isotope signatures from mixtures of natural abundance and enriched tracers. In iron metabolism studies measurement of all four isotopes of the element by high-resolution multicollector or collision cell ICP-MS allows the determination of the tracer/tracee ratio with simultaneous internal mass bias correction and lower uncertainties. This technique was applied here for the first time to study iron uptake by cucumber plants using {sup 57}Fe-enriched iron chelates of the o,o and o,p isomers of ethylenediaminedi(o-hydroxyphenylacetic) acid (EDDHA) and ethylenediamine tetraacetic acid (EDTA). Samples of root, stem, leaves, and xylem sap, after exposure of the cucumber plants to the mentioned {sup 57}Fe chelates, were collected, dried, and digested using nitric acid. The isotopic composition of iron in the samples was measured by ICP-MS using a high-resolution multicollector instrument. Mass bias correction was computed using both a natural abundance iron standard and by internal correction using isotope pattern deconvolution. It was observed that, for plants with low {sup 57}Fe enrichment, isotope pattern deconvolution provided lower tracer/tracee ratio uncertainties than the traditional method applying external mass bias correction. The total amount of the element in the plants was determined by isotope dilution analysis, using a collision cell quadrupole ICP-MS instrument, after addition of {sup 57}Fe or natural abundance Fe in a known amount which depended on the isotopic composition of the sample. (orig.)

  2. Discovery of the Mercury Isotopes

    Meierfrankenfeld, D

    2009-01-01

    Forty mercury 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. Discovery of the Einsteinium Isotopes

    Bury, A.; Fritsch, A; Ginepro, J. Q.; Heim, M; Schuh, A.; Shore, A.; Thoennessen, M.

    2009-01-01

    Seventeen einsteinium 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.

  4. Discovery of the Titanium Isotopes

    Meierfrankenfeld, D.; Thoennessen, M.

    2009-01-01

    Twentyfive titanium 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.

  5. Discovery of the Scandium Isotopes

    Meierfrankenfeld, D

    2010-01-01

    Twenty-three scandium 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.

  6. Discovery of the Tungsten Isotopes

    A. Fritsch; Ginepro, J. Q.; Heim, M.; Schuh, A.; SHORE, A.; Thoennessen, M

    2009-01-01

    Thirty-five tungsten 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.

  7. Discovery of the Vanadium Isotopes

    SHORE, A.; A. Fritsch; Heim, M.; Schuh, A.; Thoennessen, M

    2009-01-01

    Twenty-four vanadium 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.

  8. Discovery of the Arsenic Isotopes

    SHORE, A.; A. Fritsch; 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.

  9. Discovery of the Barium Isotopes

    SHORE, A.; A. Fritsch; Ginepro, J. Q.; Heim, M.; Schuh, A.; Thoennessen, M

    2009-01-01

    Thirty-eight barium 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 the Silver Isotopes

    Schuh, A.; A. Fritsch; Ginepro, J. Q.; Heim, M.; SHORE, A.; Thoennessen, M

    2009-01-01

    Thirty-eight silver 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.

  11. Discovery of the Cadmium Isotopes

    Amos, S.; Thoennessen, M

    2009-01-01

    Thirty-seven cadmium 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.

  12. Discovery of the Krypton Isotopes

    Heim, M.; A. Fritsch; Schuh, A.; SHORE, A.; Thoennessen, M

    2009-01-01

    Thirty-two krypton isotopes have been observed so far; 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.

  13. Discovery of the Iron Isotopes

    Schuh, A.; A. Fritsch; Heim, M.; SHORE, A.; Thoennessen, M

    2009-01-01

    Twenty-eight iron 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.

  14. Discovery of the Gold Isotopes

    Schuh, A.; A. Fritsch; Ginepro, J. Q.; Heim, M.; SHORE, A.; Thoennessen, M

    2009-01-01

    Thirty-six gold 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.

  15. Discovery of the Cobalt Isotopes

    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.

  16. BIPAL - a data library for computing the burnup of fissionable isotopes and products of their decay

    The BIPAL databank contains data on 100 heavy metal isotopes starting with 206Tl and finishing with 253Es. Four are stable, the others are unstable. The following data are currently stored in the databank: the serial number and name of isotopes, decay modes and, for stable isotopes, the isotopic abundance (%), numbers of P decays and Q captures, numbers of corresponding final products, branching ratios, half-lives and their units, decay constants, thermal neutron captures, and fission cross sections, and other data (mainly alpha, beta and gamma intensities). The description of data and a printout of the BIPAL library are presented. (J.B.)

  17. Single atom detection of calcium isotopes by atom trap trace analysis

    Hoekstra, S; Morgenstern, R; Wilschut, H W; Hoekstra, R

    2005-01-01

    We demonstrate a combination of an isotopically purified atom beam and a magneto-optical trap which enables the single atom detection of all stable isotopes of calcium (40, 42, 43, 44, 46 and 48). These isotopes range in abundance from 96.9 % (40Ca) to 0.004 (46Ca). The trap is loaded from an atomic beam which is decelerated in a Zeeman slower and subsequently deflected over an angle of 30 degrees by optical molasses. The isotope selectivity of the Zeeman slower and the deflection stage is investigated experimentally and compared with Monte Carlo simulations.

  18. Nitrogen 15 abundance in protein fractions of beans fertilized with (15NH4)2SO4

    Studies evaluating the protein nutritive value of beans labelled with 15 N, using nitrogen balance and the quantitation of faecal and urinary endogenous nitrogen, determined by isotopic dilution, have been extensively used. The objective of this research was to verify if the isotopic labelling of raw, freeze dried beans (Phaseolus vulgaris L., cultivar Pirata 1) with 1.394 atoms % 15 N, resulted in the same abundance of the whole flour and of the protein fractions extracted from the beans with 0.5 mol L-1 NaCl. The isotopic abundance found in the whole bean flour, in the protein extract, in the globulin and albumin fractions were respectively: 1.394 +- 0.011; 1.403 +- 0.012; 1.399 +- 0.007 and 1.399 +- 0.028 atoms % of 15 N, presenting no difference (P > 0.05). However, a difference was found (P < 0.05) between the above mentioned abundances and the isotopic abundance found in the nitrogen of the proteins in the extraction residue, which was 0.969 +- 0.084. Since the abundances did not differ, the protein nutritive indexes, such as digestibility and biological value, determined from the nitrogen balance and corrected for isotopic dilution, would not be affected by extracting the proteins from the beans with 0.5 mol L 1 NaCl. If working with the nitrogen balance of the residual proteins after extraction and even with the whole flours, these indexes could present incorrect values, since the isotopic labelling of the residual proteins was less than that of the protein fractions. (author)

  19. Stable isotopes labelled compounds

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  20. (Carbon isotope fractionation inplants)

    O' Leary, M.H.

    1990-01-01

    The objectives of this research are: To develop a theoretical and experimental framework for understanding isotope fractionations in plants; and to develop methods for using this isotope fractionation for understanding the dynamics of CO{sub 2} fixation in plants. Progress is described.

  1. Detecting isotopic ratio outliers

    An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers. 6 refs., 3 figs., 3 tabs

  2. The primordial and evolutionary abundance variations in globular-cluster stars: a problem with two unknowns

    Denissenkov, Pavel; Hartwick, David; Herwig, Falk; Weiss, Achim; Paxton, Bill

    2014-01-01

    Abundances of the proton-capture elements and their isotopes in globular-cluster stars correlate with each other in such a manner as if their variations were produced in high-temperature hydrogen burning at the same time in the past. In addition to these primordial abundance variations, the RGB stars in globular clusters, like their field counterparts, show the evolutionary variations of the C and N abundances and 12C/13C isotopic ratio. The latter are caused by extra mixing operating in the RGB star's radiative zone that separates the H-burning shell from the bottom of its convective envelope. We demonstrate that among the potential sources of the primordial abundance variations in globular-cluster stars proposed so far, such as the hot-bottom burning in massive AGB stars and H burning in the convective cores of supermassive and fast-rotating massive MS stars, only the supermassive MS stars with M > 10,000 Msun can explain all the abundance correlations without any fine-tuning of free parameters. We use our ...

  3. Using cosmogenic isotopes to measure basin-scale rates of erosion

    The authors present a new and different approach to interpreting the abundance of in situ-produced cosmogenic nuclides such as 36Cl, 26Al, and 10Be. Unlike most existing models, which are appropriate for evaluating isotope concentrations on bedrock surfaces, this model can be used to interpret isotope concentration in fluvial sediment. Because sediment is a mixture of material derived from the entire drainage basin, measured isotope abundances can be used to estimate spatially-averaged rates of erosion and sediment transport. Their approach has the potential to provide geomorphologists with a relatively simple but powerful means by which to constrain rates of landscape evolution. The model considers the flux of cosmogenic isotopes into and out of various reservoirs. Implicit in model development are the assumptions that a geomorphic steady-state has been reached and that sampled sediment is spatially and temporally representative of all sediment leaving the basin. Each year, the impinging cosmic-ray flux produces a certain quantity of cosmogenic isotopes in the rock and soil of a drainage basin. For a basin in steady state, the outgoing isotope flux is also constant. They solve for the rate of mass loss as a function of isotope abundance in the sediment, the cosmic ray attenuation length, the isotope half life, and the effective isotope production rate. There are only a few published measurements of cosmogenic isotope abundance in sediment. They calculated model denudation rates for sediment samples from Zaire and central Texas. The denudation rates they calculated appear reasonable and are similar to those they have measured directly on granite landforms in Georgia and southeastern California and those calculated for the Appalachian Piedmont

  4. Isotopes in Greenland Precipitation

    Faber, Anne-Katrine

    Greenland ice cores offer a unique opportunity to investigate the climate system behaviour. The objective of this PhD project is to investigate isotope modelling of present- day conditions and conduct model-data comparison using Greenland ice cores. Thus this thesis investigates how the integration...... 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...

  5. Surface abundances of ON stars

    Martins, F.; Simón-Díaz, S.; Palacios, A.; Howarth, I.; Georgy, C.; Walborn, N. R.; Bouret, J.-C.; Barbá, R.

    2015-06-01

    Context. Massive stars burn hydrogen through the CNO cycle during most of their evolution. When mixing is efficient or when mass transfer in binary systems occurs, chemically processed material is observed at the surface of O and B stars. Aims: ON stars show stronger lines of nitrogen than morphologically normal counterparts. Whether this corresponds to the presence of material processed through the CNO cycle is not known. Our goal is to answer this question. Methods: We performed a spectroscopic analysis of a sample of ON stars with atmosphere models. We determined the fundamental parameters as well as the He, C, N, and O surface abundances. We also measured the projected rotational velocities. We compared the properties of the ON stars to those of normal O stars. Results: We show that ON stars are usually rich in helium. Their CNO surface abundances are fully consistent with predictions of nucleosynthesis. ON stars are more chemically evolved and rotate - on average - faster than normal O stars. Evolutionary models including rotation cannot account for the extreme enrichment observed among ON main sequence stars. Some ON stars are members of binary systems, but others are single stars as indicated by stable radial velocities. Mass transfer is therefore not a simple explanation for the observed chemical properties. Conclusions: We conclude that ON stars show extreme chemical enrichment at their surface, consistent with nucleosynthesis through the CNO cycle. Its origin is not clear at present. Based on observations obtained 1) at the Anglo-Australian Telescope; 2) at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii; 3) at the ESO/La Silla Observatory under programs 081.D-2008, 083.D-0589, 086.D-0997; 4) the Nordic Optical Telescope, operated on the island of La

  6. Isotopic approach to the provenance study of artifacts

    Isotopic abundance ratios, which are proved to be generally constant, are known to vary, for certain elements, from one place to another. Light elements, such as hydrogen, lithium, boron, carbon, nitrogen, oxygen and sulfur, show measurable variations of their isotope ratios due to isotopic fractionation which takes place during geochemical or biochemical processes. Isotope ratios of strontium and lead vary due to the decay of long-lived radioactive nuclides 87Rb and 238U-235U-232Th, respectively. Such isotopic anomalies can be applicable to provenance studies of archaeological objects. Thus, 13C/12C, 18O/16O, or 87Sr/86Sr were used to examine the authenticity of Greek marble statues. Also, lead isotope ratios have been used since mid-1960s extensively for provenance studies of glasses and bronzes of different civilizations. As an example, the author presents a series of his own works on lead isotope ratios applied to ancient Japanese bronzes, which are summarized as follows. 1) It was generally observed that lead isotope ratios reflect difference in culture to which bronzes belong. 2) Mirrors in the Western Han period (206 B.C. - A.D.8) are clearly distinguished by lead isotope ratios from those made after the mid-Eastern Han period (ca.A.D.150 - 300). 3) Korean mirrors and weapons excavated from the Yayoi sites contain lead of easily recognizable Mississippi Valley type. 4) Bronze objects made in Japan (imitative Han style mirrors, Dotaku, imitative weapons, arrowheads etc.) in the Yayoi and Kofun periods are classified by lead isotope ratios in the following order: the Korean mirror type to the Western Han mirror type in the Yayoi period and the mid- to post- Han mirror type in the Kofun period. 5) Indigenous Japanese lead seems to have been used after the mid-7th century. (J.P.N.)

  7. Origin of Cosmic Chemical Abundances

    Maio, Umberto

    2015-01-01

    Cosmological N-body hydrodynamic computations following atomic and molecular chemistry (e$^-$, H, H$^+$, H$^-$, He, He$^+$, He$^{++}$, D, D$^+$, H$_2$, H$_2^+$, HD, HeH$^+$), gas cooling, star formation and production of heavy elements (C, N, O, Ne, Mg, Si, S, Ca, Fe, etc.) from stars covering a range of mass and metallicity are used to explore the origin of several chemical abundance patterns and to study both the metal and molecular content during simulated galaxy assembly. The resulting trends show a remarkable similarity to up-to-date observations of the most metal-poor damped Lyman-$\\alpha$ absorbers at redshift $z\\gtrsim 2$. These exhibit a transient nature and represent collapsing gaseous structures captured while cooling is becoming effective in lowering the temperature below $\\sim 10^4\\,\\rm K$, before they are disrupted by episodes of star formation or tidal effects. Our theoretical results agree with the available data for typical elemental ratios, such as [C/O], [Si/Fe], [O/Fe], [Si/O], [Fe/H], [O/...

  8. Significant biases affecting abundance determinations

    Wesson, Roger

    2015-08-01

    I have developed two highly efficient codes to automate analyses of emission line nebulae. The tools place particular emphasis on the propagation of uncertainties. The first tool, ALFA, uses a genetic algorithm to rapidly optimise the parameters of gaussian fits to line profiles. It can fit emission line spectra of arbitrary resolution, wavelength range and depth, with no user input at all. It is well suited to highly multiplexed spectroscopy such as that now being carried out with instruments such as MUSE at the VLT. The second tool, NEAT, carries out a full analysis of emission line fluxes, robustly propagating uncertainties using a Monte Carlo technique.Using these tools, I have found that considerable biases can be introduced into abundance determinations if the uncertainty distribution of emission lines is not well characterised. For weak lines, normally distributed uncertainties are generally assumed, though it is incorrect to do so, and significant biases can result. I discuss observational evidence of these biases. The two new codes contain routines to correctly characterise the probability distributions, giving more reliable results in analyses of emission line nebulae.

  9. A mass spectrometric strategy for absolute quantification of Plasmodium falciparum proteins of low abundance

    Hyde John E; Southworth Paul M; Sims Paul FG

    2011-01-01

    Abstract Selected reaction monitoring mass spectrometry has been combined with the use of an isotopically labelled synthetic protein, made up of proteotypic tryptic peptides selected from parasite proteins of interest. This allows, for the first time, absolute quantification of proteins from Plasmodium falciparum. This methodology is demonstrated to be of sufficient sensitivity to quantify, even within whole cell extracts, proteins of low abundance from the folate pathway as well as more abun...

  10. Trophodynamics and functional feeding groups of North Sea fauna: a combined stable isotope and fatty acid approach

    Kürten, B.; Frutos, I.; Struck, U.; Painting, S.J.; Polunin, N.V.C.; Middelburg, J.J.

    2012-01-01

    The trophodynamics of pelagic and benthic animals of the North Sea, North Atlantic shelf, were assessed using stable isotope analysis (SIA) of natural abundance carbon and nitrogen isotopes, lipid fingerprinting and compound-specific SIA (CSIA) of phospholipid-derived fatty acids (PLFAs). Zooplankto

  11. Rotational-isotopic symmetries

    In this note we submit a nonlocal (integral) generalization of the rotational-isotopic symmetries O-circumflex(3) introduced in preceding works for nonlinear and nonhamiltonian systems in local approximation. By recalling that the Lie-isotopic theory naturally admits nonlocal terms when all embedded in the isounit, while the conventional symplectic geometry is strictly local-differential, we introduce the notion of symplectic-isotopic two-forms, which are exact symplectic two-forms admitting a factorization into the Kronecker product of a canonical two-form time the isotopic element of an underlying Euclidean-isotopic space. Topological consistency is then achieved by embedding all nonlocal terms in the isounit of the iso-cotangent bundle, while keeping the local topology for the canonical part. In this way, we identify the symplectic-isotopic geometry as being the natural geometrical counterpart of the Lie-isotopic theory. The results are used for the introduction of the notion of Birkhoffian angular momentum, that is, the generalization of the conventional canonical angular momentum which is applicable to Birkhoffian systems with generally nonlinear, nonlocal and nonhamiltonian internal forces. The generators J (and the parameters θ) coincide with the conventional quantities. Nevertheless, the quantity J is defined on the underlying Euclidean-isotopic space, by therefore acquiring a generalized magnitude. The isocommutation rules and isoexponentiation of the Birkhoffian angular momentum are explicitly computed and shown to characterize the most general known nonlinear and nonlocal realization of the isorotational symmetry. The local isomorphisms between the infinitely possible isotopes O-circumflex(3) and the conventional symmetry O(3) is proved. Finally the isosymmetries O-circumflex(3) are used to characterize the conserved, total, Birkhoffian angular momentum of closed nonselfadjoint systems. (author). 4 refs

  12. Isotopically controlled semiconductors

    Haller, Eugene E.

    2006-06-19

    The following article is an edited transcript based on the Turnbull Lecture given by Eugene E. Haller at the 2005 Materials Research Society Fall Meeting in Boston on November 29, 2005. The David Turnbull Lectureship is awarded to recognize the career of a scientist who has made outstanding contributions to understanding materials phenomena and properties through research, writing, and lecturing, as exemplified by the life work of David Turnbull. Haller was named the 2005 David Turnbull Lecturer for his 'pioneering achievements and leadership in establishing the field of isotopically engineered semiconductors; for outstanding contributions to materials growth, doping and diffusion; and for excellence in lecturing, writing, and fostering international collaborations'. The scientific interest, increased availability, and technological promise of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled semiconductor crystals. This article reviews results obtained with isotopically controlled semiconductor bulk and thin-film heterostructures. Isotopic composition affects several properties such as phonon energies, band structure, and lattice constant in subtle, but, for their physical understanding, significant ways. Large isotope-related effects are observed for thermal conductivity in local vibrational modes of impurities and after neutron transmutation doping. Spectacularly sharp photoluminescence lines have been observed in ultrapure, isotopically enriched silicon crystals. Isotope multilayer structures are especially well suited for simultaneous self- and dopant-diffusion studies. The absence of any chemical, mechanical, or electrical driving forces makes possible the study of an ideal random-walk problem. Isotopically controlled semiconductors may find applications in quantum computing, nanoscience, and spintronics.

  13. Application of high-precision isotope ratio monitoring mass spectrometry to identify the biosynthetic origins of proteins

    Apostol, Izydor; Brooks, Paul D.; Mathews, Antony J.

    2001-01-01

    Isotope ratio monitoring (IRM) mass spectrometry was used to measure the relative abundance of stable isotopes in several samples of adult human hemoglobin expressed in E. coli, yeast, and human blood. The results showed significant differences in the distribution of 15N and 13C isotopes among hemoglobin samples produced in these organisms. This indicates that IRM mass spectrometry can be used in forensic protein chemistry to identify the origin of protein expression.

  14. Stable carbon isotope analysis of nucleic acids to trace sources of dissolved substrates used by estuarine bacteria.

    Coffin, R B; Velinsky, D J; R. Devereux; Price, W A; Cifuentes, L A

    1990-01-01

    The natural abundance of stable carbon isotopes measured in bacterial nucleic acids extracted from estuarine bacterial concentrates was used to trace sources of organic matter for bacteria in aquatic environments. The stable carbon isotope ratios of Pseudomonas aeruginosa and nucleic acids extracted from cultures resembled those of the carbon source on which bacteria were grown. The carbon isotope discrimination between the substrate and total cell carbon from bacterial cultures averaged 2.3%...

  15. Oxygen isotopic ratios toward molecular clouds in the Galactic disk

    We present our observations of the J = 1 − 0 rotation transitions in molecular isotopes C18O and C17O toward a sample of molecular clouds with different galactocentric distances, using the Delingha 13.7m (DLH 13.7 m) telescope, administered by Purple Mountain Observatory, and its 9-beam SIS receiver. Complementary observations toward several sources with large galactocentric distance are obtained with the IRAM 30m and Mopra 22m telescopes. C18O/C17O abundance ratios reflecting the 18O/17O isotope ratios are obtained from integrated intensity ratios of C18O and C17O. We derived the ratio value for 13 sources covering a galactocentric distance range of 3kpc to 16kpc. In combination with our mapping results that provide a ratio value of 3.01±0.14 in the Galactic center region, it shows that the abundance ratio tends to increase with galactocentric distance, i.e., it supports a radial gradient along the Galactic disk for the abundance ratio. This is consistent with the inside-out formation scenario of our Galaxy. However, our results may suffer from small samples with large galactocentric distance. Combining our data with multi-transition lines of C18O and C17O will be helpful for constraining opacities and abundances and further confirming the Galactic radial gradient shown by the isotope ratio 18O/17O. (paper)

  16. Hydrocarbon Reserves: Abundance or Scarcity

    IFP and the OAPEC jointly organize a regular international seminar dealing with world oil-related problems appearing in the news. For the first time, this seminar has been opened to oil and gas company specialists, service companies, research centers and independents. This year's theme concerns oil and gas reserves: are they abundant or are we headed towards the shortages announced by some experts? This theme is especially topical in that: oil and gas currently meet two thirds of world energy needs and almost completely dominate the transport sector; the reserves declared by the OAPEC countries account for nearly half of world reserves; the price of a barrel of oil went through the roof in 2004; world energy demand is growing fast and alternative sources of energy are far from ready to take over from oil and gas in the next few decades. Since the reserves correspond to the volume it is technically and economically viable to produce, the seminar has, of course, dealt with the technical and economic questions that arise in connection with exploration and production, but it has also considered changes in the geopolitical context. Presentations by the leading companies of the OAPEC countries and by the IFP group were completed by presentation from the International Energy Agency (IEA), the United States Geological Survey (USGS), the IHS Energy Group, Total and Gaz de France. This document gathers the transparencies of the following presentations: Hydrocarbon reserves in OAPEC members countries: current and future (M. Al-Lababidi); Non OAPEC liquid reserves and production forecasts (Y. Mathieu); World oil and gas resources and production outlook (K. Chew); Global investments in the upstream (F. Birol); Total's policy in the oil and gas sector (C. de Margerie); Gaz de France's policy in the oil and gas sector (J. Abiteboul); NOC/IOC's opportunities in OPEC countries (I. Sandrea); Relationships between companies, countries and investors: How they may impact on the growth

  17. Hydrocarbon Reserves: Abundance or Scarcity

    NONE

    2005-07-01

    IFP and the OAPEC jointly organize a regular international seminar dealing with world oil-related problems appearing in the news. For the first time, this seminar has been opened to oil and gas company specialists, service companies, research centers and independents. This year's theme concerns oil and gas reserves: are they abundant or are we headed towards the shortages announced by some experts? This theme is especially topical in that: oil and gas currently meet two thirds of world energy needs and almost completely dominate the transport sector; the reserves declared by the OAPEC countries account for nearly half of world reserves; the price of a barrel of oil went through the roof in 2004; world energy demand is growing fast and alternative sources of energy are far from ready to take over from oil and gas in the next few decades. Since the reserves correspond to the volume it is technically and economically viable to produce, the seminar has, of course, dealt with the technical and economic questions that arise in connection with exploration and production, but it has also considered changes in the geopolitical context. Presentations by the leading companies of the OAPEC countries and by the IFP group were completed by presentation from the International Energy Agency (IEA), the United States Geological Survey (USGS), the IHS Energy Group, Total and Gaz de France. This document gathers the transparencies of the following presentations: Hydrocarbon reserves in OAPEC members countries: current and future (M. Al-Lababidi); Non OAPEC liquid reserves and production forecasts (Y. Mathieu); World oil and gas resources and production outlook (K. Chew); Global investments in the upstream (F. Birol); Total's policy in the oil and gas sector (C. de Margerie); Gaz de France's policy in the oil and gas sector (J. Abiteboul); NOC/IOC's opportunities in OPEC countries (I. Sandrea); Relationships between companies, countries and investors: How they may

  18. CALCIUM ISOTOPE COMPOSITION OF METEORITES, EARTH, AND MARS

    The relative abundances of calcium isotopes in the mass range 40-44 were measured in primitive and differentiated meteorites and igneous rocks from Earth and Mars in search of non-mass-dependent variations that could provide clues about early solar system processes. Most bulk samples of planetary materials have calcium isotopic compositions identical with Earth's within the current resolution of about 0.01% in 40Ca/44Ca. Possible exceptions include carbonaceous chondrites, some ordinary chondrites, and two samples of calcium-aluminum-rich inclusions, which have small excesses of 40Ca. The samples with 40Ca excesses are also known to have 50Ti and 135Ba excesses and 142Nd and 144Sm deficits. Collectively these data from refractory elements suggest that the planetary embryos represented by chondrites preserve isotopic heterogeneity that reflects different nucleosynthetic sources. No late admixture from a single nucleosynthetic source can explain all observations. The results are most compatible with variable proportions of material derived from Type II supernovae. The initial calcium isotope compositions of Earth and Mars are indistinguishable and similar to the 40Ca abundance found in some chondrites and all differentiated meteorites studied. It appears that isotopic heterogeneity in calcium was still present at the completion of disk formation but was homogenized during planetary accretion.

  19. High precision isotopic ratio analysis of volatile metal chelates

    High precision isotope ratio measurements have been made for a series of volatile alkaline earth and transition metal chelates using conventional GC/MS instrumentation. Electron ionization was used for alkaline earth chelates, whereas isobutane chemical ionization was used for transition metal studies. Natural isotopic abundances were determined for a series of Mg, Ca, Cr, Fe, Ni, Cu, Cd, and Zn chelates. Absolute accuracy ranged between 0.01 and 1.19 at. %. Absolute precision ranged between +-0.01-0.27 at. % (RSD +- 0.07-10.26%) for elements that contained as many as eight natural isotopes. Calibration curves were prepared using natural abundance metals and their enriched 50Cr, 60Ni, and 65Cu isotopes covering the range 0.1-1010.7 at. % excess. A separate multiple isotope calibration curve was similarly prepared using enriched 60Ni (0.02-2.15 at. % excess) and 62Ni (0.23-18.5 at. % excess). The samples were analyzed by GC/CI/MS. Human plasma, containing enriched 26Mg and 44Ca, was analyzed by EI/MS. 1 figure, 5 tables

  20. Oxygen isotopes and lakes

    Leng, Melanie; Dean, Jonathan

    2014-01-01

    Isotopes are variations of a particular chemical element. It is all to do with the number of neutrons. Oxygen has two main isotopes: 18O which has 10 neutrons and 8 protons; and 16O which has 8 neutrons and 8 protons. Although these variants have a different number of neutrons (and therefore a different atomic mass), the number of protons remains the same, and they are still classed as the same element. Isotopes are analysed in terms of ratios such as 18O/16O which is shortened to δ18O (δ...

  1. Carbon isotope techniques

    This book is a hands-on introduction to using carbon isotope tracers in experimental biology and ecology. It is a bench-top reference with protocols for the study of plants, animals, and soils. The 11C, 12C, 13C, and 14C carbon isotopes are considered and standard techniques are described by established authors. The compilation includes the following features: specific, well-established, user-oriented techniques; carbon cycles in plants, animals, soils, air, and water; isotopes in ecological research; examples and sample calculations

  2. Isotopes in Australian environmental analysis

    Full text: ANSTO Environment is playing a pioneering role in developing new methods for monitoring adherence to the Nuclear Non-proliferation Treaty. Working with the IAEA Department of Safeguards, new analytical procedures have been developed to assist with their environmental monitoring programme. Signatures of nuclear activities, in the form of trace amounts of radioisotopes in environmental samples, can be used to identify undeclared nuclear facilities or undeclared activities at declared facilities. At ANSTO we have developed the use of Accelerator Mass Spectrometry (AMS) for analysis of 236U in environmental samples. 236U is a sensitive indicator of irradiated uranium. AMS is also used to detect the long- lived fission product 129I at extremely low levels. The presence of 129I can be a signature of reprocessing. ANSTO performs analyses of these radioisotopes as an accredited member of the IAEA Safeguards network of analytical laboratories. Australian soldiers on duty in the Gulf risk possible exposure to depleted uranium. Depleted uranium is the uranium that is left after most of the radioactive isotopes are removed for nuclear fuel. Due to its high density, it is the ideal material for use in armour-piercing ammunition and in armour for fighting vehicles. However, like any heavy metal, it is toxic in high doses. Depleted uranium enters the body through inhalation of the dust- like particles, ingestion of contaminated food or through wounds. At ANSTO, a sensitive analytical technique based on isotope dilution and inductively coupled plasma mass spectrometry (ICP-MS) was used to detect depleted uranium in urine samples. By addition of known quantities of 236U (isotope dilution) to the urine samples and measuring the relative abundances of different isotopes (236U, 235U and 238U) of uranium by ICP-MS, we are able to quantify (quantification limit of 20 ng/L) and distinguish between natural and depleted uranium. In Australia, there are legislative limits on the

  3. The Sulfur Abundance Anomaly in Planetary Nebulae

    Henry, R B C; Kwitter, K B; Milingo, M B

    2006-01-01

    The failure of S and O abundances in most planetary nebulae to display the same strong direct correlation that is observed in extragalactic H II regions represents one of the most perplexing problems in the area of PN abundances today. Galactic chemical evolution models as well as large amounts of observational evidence from H II region studies support the contention that cosmic abundances of alpha elements such as O, Ne, S, Cl, and Ar increase together in lockstep. Yet abundance results from the Henry, Kwitter, & Balick (2004) database show a strong tendency for most PNe to have S abundances that are significantly less than expected from the observed level of O. One reasonable hypothesis for the sulfur anomaly is the past failure to properly measure the abundances of unseen ionization stages above S^+2. Future observations with Spitzer will allow us to test this hypothesis.

  4. Oxygen abundances in nearby dwarf irregular galaxies

    Oxygen abundances are obtained by optical spectrophotometry of H II regions in seven nearby dwarf irregular galaxies. All of these yield oxygen abundances of less than 1/10 of the solar value, and most are in the range of 3-5 percent of the solar value. This suggests that observations of nearby dwarf galaxies may provide an effective means for studying the chemical evolution of low-mass galaxies and, possibly, the primordial helium abundance. A strong correlation is found between the oxygen abundances and absolute magnitudes for nearby irregular galaxies. This correlation will be useful for estimating abundances of irregular galaxies without observable H II regions, and possibly as a distance indicator for irregular galaxies with known abundances. It is inferred from this relationship that infall is no more important in irregular galaxies with extremely large H I halos than in typical irregular galaxies. 72 refs

  5. Stellar abundances of beryllium and CUBES

    Smiljanic, R

    2014-01-01

    Stellar abundances of beryllium are useful in different areas of astrophysics, including studies of the Galactic chemical evolution, of stellar evolution, and of the formation of globular clusters. Determining Be abundances in stars is, however, a challenging endeavor. The two Be II resonance lines useful for abundance analyses are in the near UV, a region strongly affected by atmospheric extinction. CUBES is a new spectrograph planned for the VLT that will be more sensitive than current instruments in the near UV spectral region. It will allow the observation of fainter stars, expanding the number of targets where Be abundances can be determined. Here, a brief review of stellar abundances of Be is presented together with a discussion of science cases for CUBES. In particular, preliminary simulations of CUBES spectra are presented, highlighting its possible impact in investigations of Be abundances of extremely metal-poor stars and of stars in globular clusters.

  6. Climate and local abundance in freshwater fishes

    Knouft, Jason H; Anthony, Melissa M.

    2016-01-01

    Identifying factors regulating variation in numbers of individuals among populations across a species' distribution is a fundamental goal in ecology. A common prediction, often referred to as the abundant-centre hypothesis, suggests that abundance is highest near the centre of a species' range. However, because of the primary focus on the geographical position of a population, this framework provides little insight into the environmental factors regulating local abundance. While range-wide va...

  7. Monitoring Butterfly Abundance: Beyond Pollard Walks

    Pellet, Jérôme; Bried, Jason T.; Parietti, David; Gander, Antoine; Heer, Patrick O.; Cherix, Daniel; Arlettaz, Raphaël

    2012-01-01

    Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly...

  8. Oxygen isotope composition of trinitite postdetonation materials.

    Koeman, Elizabeth C; Simonetti, Antonio; Chen, Wei; Burns, Peter C

    2013-12-17

    Trinitite is the melt glass produced subsequent the first nuclear bomb test conducted on July 16, 1945, at White Sands Range (Alamagordo, NM). The geological background of the latter consists of arkosic sand that was fused with radioactive debris and anthropogenic materials at ground zero subsequent detonation of the device. Postdetonation materials from historic nuclear weapon test sites provide ideal samples for development of novel forensic methods for attribution and studying the chemical/isotopic effects of the explosion on the natural geological environment. In particular, the latter effects can be evaluated relative to their spatial distribution from ground zero. We report here δ(18)O(‰) values for nonmelted, precursor minerals phases (quartz, feldspar, calcite), "feldspathic-rich" glass, "average" melt glass, and bulk (natural) unmelted sand from the Trinity site. Prior to oxygen isotope analysis, grains/crystals were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to determine their corresponding major element composition. δ(18)O values for bulk trinitite samples exhibit a large range (11.2-15.5‰) and do not correlate with activity levels for activation product (152)Eu; the latter levels are a function of their spatial distribution relative to ground zero. Therefore, the slow neutron flux associated with the nuclear explosion did not perturb the (18)O/(16)O isotope systematics. The oxygen isotope values do correlate with the abundances of major elements derived from precursor minerals present within the arkosic sand. Hence, the O isotope ratios documented here for trinitite melt glass can be attributed to a mixture of the respective signatures for precursor minerals at the Trinity site prior to the nuclear explosion. PMID:24304329

  9. Investigating uranium isotopic distributions in environmental samples using AMS and MC-ICPMS

    Major, minor and trace uranium isotopes were measured at Lawrence Livermore National Laboratory in environmentally acquired samples using different instruments to span large variations in concentrations. Multi-collector inductively-coupled plasma mass spectrometry (MC-ICPMS) can be used to measure major and minor isotopes: 238U, 235U, 234U and 236U. Accelerator mass spectrometry (AMS) can be used to measure minor and trace isotopes: 234U, 236U and 233U. The main limit of quantification for minor or trace uranium isotopes is the abundance sensitivity of the measurement technique; i.e. the ability to measure a minor or trace isotope of mass M in the presence of a major isotope at M ± 1 mass units. The abundance sensitivity for 236U/235U isotope ratio measurements using MC-ICPMS is around ∼2 x 10-6. This compares with a 236U/235U abundance sensitivity of ∼1 x 10-7 for the current AMS system, with the expectation of 2-3 orders of magnitude improvement in sensitivity with the addition of another high energy filter. Comparing 236U/234U from MC-ICPMS and AMS produced agreement within ∼10% for samples at 236U levels high enough to be measurable by both techniques

  10. The chemical composition of red giants in 47 Tucanae. II. Magnesium isotopes and pollution scenarios

    Thygesen, A O; Ludwig, H -G; Ventura, P; Yong, D; Collet, R; Christlieb, N; Melendez, J; Zaggia, S

    2016-01-01

    The phenomenon of multiple populations in globular clusters is still far from understood, with several proposed mechanisms to explain the observed behaviour. The study of elemental and isotopic abundance patterns are crucial for investigating the differences among candidate pollution mechanisms. We derive magnesium isotopic ratios for 13 stars in the globular cluster 47 Tucanae (NGC 104) to provide new, detailed information about the nucleosynthesis that has occurred within the cluster. For the first time, the impact of 3D model stellar atmospheres on the derived Mg isotopic ratios is investigated. Using both tailored 1D atmospheric models and 3D hydrodynamical models, we derive magnesium isotopic ratios from four features of MgH near 5135{\\AA} in 13 giants near the tip of the RGB, using high signal-to-noise, high-resolution spectra. We derive the magnesium isotopic ratios for all stars and find no significant offset of the isotopic distribution between the pristine and the polluted populations. Furthermore, ...

  11. Abundance of introduced species at home predicts abundance away in herbaceous communities

    Firn, Jennifer; Moore, Joslin L.; MacDougall, Andrew S.; Borer, Elizabeth T.; Seabloom, Eric W.; HilleRisLambers, Janneke; Harpole, W. Stanley; Cleland, Elsa E.; Brown, Cynthia S.; Knops, Johannes M.H.; Prober, Suzanne M.; Pyke, David A.; Farrell, Kelly A.; Bakker, John D.; O'Halloran, Lydia R.; Adler, Peter B.; Collins, Scott L.; D'Antonio, Carla M.; Crawley, Michael J.; Wolkovich, Elizabeth M.; La Pierre, Kimberly J.; Melbourne, Brett A.; Hautier, Yann; Morgan, John W.; Leakey, Andrew D.B.; Kay, Adam; McCulley, Rebecca; Davies, Kendi F.; Stevens, Carly J.; Chu, Cheng-Jin; Holl, Karen D.; Klein, Julia A.; Fay, Phillip A.; Hagenah, Nicole; Kirkman, Kevin P.; Buckley, Yvonne M.

    2011-01-01

    Many ecosystems worldwide are dominated by introduced plant species, leading to loss of biodiversity and ecosystem function. A common but rarely tested assumption is that these plants are more abundant in introduced vs. native communities, because ecological or evolutionary-based shifts in populations underlie invasion success. Here, data for 26 herbaceous species at 39 sites, within eight countries, revealed that species abundances were similar at native (home) and introduced (away) sites - grass species were generally abundant home and away, while forbs were low in abundance, but more abundant at home. Sites with six or more of these species had similar community abundance hierarchies, suggesting that suites of introduced species are assembling similarly on different continents. Overall, we found that substantial changes to populations are not necessarily a pre-condition for invasion success and that increases in species abundance are unusual. Instead, abundance at home predicts abundance away, a potentially useful additional criterion for biosecurity programmes.

  12. Isotopically controlled semiconductors

    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.

  13. Method for isotope separation

    The inventor proposes a method for separating isotopes from gaseous compounds by selective excitation by means of laser beams for such cases where the reaction partners each consist of several isotopes. For example, separation of 235U and 238U in the form of UCl6 is mentioned with 35Cl and 37Cl existing in the natural composition of 76:24. According to the invention, after isolating the reaction product obtained in a way already known, the remaining fraction of the compound mixture is brought together with the reaction partner present in the natural isotope composition, in a heated flow path. Thereby by isotope exchange of the latter regeneration will take place, and the mixture can pass again through the separation plant in initial composition. (orig./PW)

  14. Isotope Production Facility (IPF)

    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...

  15. Calcium stable isotope geochemistry

    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.

  16. Clumped Isotopes Applied to Carbonate Diagenesis and High Temperature Systems

    John, C. M.; Jourdan, A.; Kluge, T.; Dale, A.; Davis, S.; Vandeginste, V.

    2012-12-01

    The field of clumped isotopes is concerned with the state of ordering of natural substances and aims at constraining the abundance of 18O-13C bonds (i.e. a 'clump') within the lattice of carbonate minerals. Measuring the difference between the abundance of 18O-13C bonds in a sample relative to a stochastic distribution of isotopologues offers a single-phase paleothermometer applicable to all carbonate phases. Most of the applications of clumped isotopes to date have been in the field of paleoclimate, but applications to diagenetic systems are becoming more common. The independence of clumped isotopes from the isotopic composition of the diagenetic fluid reduces ambiguities when interpreting paragenesis, fluid flow history, and thermal history of basins. This presentation will synthesize the results of several projects within our group that collectively aim at understanding and applying clumped isotopes to diagenetic systems. One example of project including diagenesis and clumped isotope is a study of low-temperature diagenetic calcite in a salt dome in Oman (Jebel Madar). Jebel Madar is an ideal case study as large fracture-related crystals can be sampled for both clumped isotopes and fluid inclusions. Results show a good match between single-phase fluid inclusions suggesting temperature of precipitations below 90-50°C, and clumped isotope data measured on the same crystals. The low-temperature study reveals the history of gradual cooling and progressive mixing between two sources of diagenetic fluids in the fracture of Jebel Madar, and highlights the potential of clumped isotope for diagenetic studies. However, applications at high-temperatures are currently more challenging because of the lack of empirical calibrations above 50°C. A second project is thus focused on a series of high-temperature lab precipitation experiments for calibrations at high temperature, while a third project explores applicability of clumped isotopes to cemented siliciclastic units

  17. Isotopes in everyday life

    Isotopes represent a tool which can do certain jobs better, easier, quicker, more simply and cheaper than competitive methods. Some measurements could not be done at all without the use of isotopes as there are no alternative methods available. A short review of these tools of science in their different fields is given: food and agriculture, human health applications, industry, hydrology, geology, geochemistry, geophysics and dating, environment, basic scientific research

  18. Canada's medical isotope strategy

    This paper details Canada's medical isotope strategy and the role of the Canadian Government in the security of the isotope supply chain. The government's role is to promote health and safety of Canadians, establish appropriate regulatory framework, allow the markets to work, facilitate international collaboration, fund high-risk early stage research and development, encourage private sector investment in innovation and support and respect environmental and non-proliferation goals.

  19. Separating isotopes by laser

    Isotope separation by laser radiation is proving a very promising method for obtaining large scale isotope production at low cost and is particularly relevant to the enrichment of 235U for the nuclear power industry. Various methods for laser separation, differing mainly in the way the selectively excited atoms or molecules are extracted, are discussed. The efficiency of the various methods, which is the controlling factor in determining their practical viability and some of the problems encountered are examined. (UK)

  20. Isotope toolbox turns 10

    Wenander, Fredrik; Riisager, Karsten

    2012-01-01

    REX-ISOLDE, one of CERN’s most compact accelerators, has just celebrated its 10th anniversary. The machine’s versatility provides radioactive ion beams across the range of nuclear isotopes.......REX-ISOLDE, one of CERN’s most compact accelerators, has just celebrated its 10th anniversary. The machine’s versatility provides radioactive ion beams across the range of nuclear isotopes....

  1. Isotopes in environmental research

    Radioactive and stable isotopes have long been considered a very efficient tool for studying physical and biological aspects of how the global ecosystem functions. Their applications in environmental research are numerous, embracing research at all levels. This article looks at only a few of the approaches to environmental problems that involve the use of isotopes. Special attention is given to studies of the Amazon Basin. Environmental isotopes are very efficient tools in water cycle studies. Tritium, a radioactive tracer, is especially useful in studying dynamics of water movement in different compartments of the hydrosphere, both on the local and global scales. Heavy stable isotopes of hydrogen and oxygen (deuterium and oxygen-18) provide information about steady-state characteristics of the water cycle. Isotope methods, some relatively new, have a major role in site-specific studies. Some indicative examples include: Studying turnover of organic matter. Changes in the carbon-13/carbon-12 isotopic ratio of organic matter were used to determine the respective contributions of organic carbon derived from forest and pasture. Studying biological nitrogen fixation. One of the ways nitrogen levels in soil can be maintained for productivity is by biological nitrogen fixation. Studying nitrogen availability and losses. The experimental use of nitrogen-15 is invaluable for defining losses of soil nitrogen to the atmosphere and to groundwater. Studies can similarly be done with stable and radioactive sulphur isotopes. This article indicates some potential uses of isotopes in environmental research. While the major problem of global climate change has not been specifically addressed here, the clearing of the Amazon forest, one focus of the IAEA's environmental programme, may have serious consequences for the global climate. These include substantial reduction of the amount of latent heat transported to the regions outside the tropics and acceleration of the greenhouse

  2. Experience with a General Gamma-Ray Isotopic Analysis Approach

    Ruhter, W D

    2003-06-18

    The gamma-ray data analysis methodology originally developed for the MGA code to determine the relative detection efficiency curve may also be used to determine the relative amounts of the isotopes being measured. This analysis approach is based on the fact that the intensity of any given gamma ray from a sample is determined by the amount of the emitting isotope present in the sample, the emission probability for the gamma ray being measured, the sample self attenuation, the attenuation due to absorbers between the sample and detector, and the detector efficiency. An equation can be written that describes a measured gamma-ray peak intensity in terms of these parameters. By selecting appropriate gamma-ray peaks from the isotopes of interest, we can solve a set of equations for the values of the parameters in any particular measurement including the relative amounts of the selected isotopes. The equations representing the peak intensities are very nonlinear and require an iterative least squares method to solve. We have developed software to ensure that during the iterative process the parameters stay within their appropriate ranges and converge properly in solving the set of equations under various measurement conditions. We have utilized and reported on this approach for determining the plutonium isotopic abundances in samples enriched in Pu-238 and to determine the U-235 enrichment of uranium samples in thick-walled containers. Recently, we have used this approach to determine the plutonium isotopic abundances of plutonium samples in thick-walled containers. We will report on this most recent application, and how this general approach can be adapted quickly to any isotopic analysis problem.

  3. Isotope heated thermal batteries

    A deferred action thermal battery is described that includes a quantity of radioactive isotope normally positioned so that only a small part of the thermal energy generated by the isotope is received by the battery, but adapted, when the battery is rendered active, to be moved automatically to a position where a large part of the thermal energy is received. The battery may comprise a chamber containing its cells and a second chamber part of which is remote from the cells for normal storage of the isotope and part of which is adjacent to the cells; the isotope is moved to the latter part when the battery is activated. The cell chamber is preferably toroidal and surrounds the second portion of the isotope chamber. The isotope may be contained in a carriage held by a retaining means adapted for release when the battery is activated, resilient means then moving the carriage to the active position. The retaining means may be a wire that disintegrates on the passage of electric current, the current also igniting a combustible composition to activate the battery. The object is to provide thermal batteries having an extended life. (U.K.)

  4. The isotopic distribution conundrum.

    Valkenborg, Dirk; Mertens, Inge; Lemière, Filip; Witters, Erwin; Burzykowski, Tomasz

    2012-01-01

    Although access to high-resolution mass spectrometry (MS), especially in the field of biomolecular MS, is becoming readily available due to recent advances in MS technology, the accompanied information on isotopic distribution in high-resolution spectra is not used at its full potential, mainly because of lack of knowledge and/or awareness. In this review, we give an insight into the practical problems related to calculating the isotopic distribution for large biomolecules, and present an overview of methods for the calculation of the isotopic distribution. We discuss the key events that triggered the development of various algorithms and explain the rationale of how and why the various isotopic-distribution calculations were performed. The review is focused around the developmental stages as briefly outlined below, starting with the first observation of an isotopic distribution. The observations of Beynon in the field of organic MS that chlorine appeared in a mass spectrum as two variants with odds 3:1 lie at the basis of the first wave of algorithms for the calculation of the isotopic distribution, based on the atomic composition of a molecule. From here on, we explain why more complex biomolecules such as peptides exhibit a highly complex isotope pattern when assayed by MS, and we discuss how combinatorial difficulties complicate the calculation of the isotopic distribution on computers. For this purpose, we highlight three methods, which were introduced in the 1980s. These are the stepwise procedure introduced by Kubinyi, the polynomial expansion from Brownawell and Fillippo, and the multinomial expansion from Yergey. The next development was instigated by Rockwood, who suggested to decompose the isotopic distribution in terms of their nucleon count instead of the exact mass. In this respect, we could claim that the term "aggregated" isotopic distribution is more appropriate. Due to the simplification of the isotopic distribution to its aggregated counterpart

  5. Cosmic rays interactions and the abundances of the chemical elements

    Our Galaxy is the largest nuclear interaction experiment which we know, because of the interaction between cosmic ray particles and the interstellar material. Cosmic rays are particles, which have been accelerated in the Galaxy or in extragalactic space. Cosmic rays come as protons, electrons, heavier nuclei, and their antiparticles. Up to energies up to some tens of TeV of particle energy it is possible to derive chemical abundances of cosmic rays. It has been proposed that cosmic ray particles can be attributed to three main sites of origin and acceleration, a) supernova shocks in the interstellar medium, b) supernova shocks in a stellar wind of the predecessor star, and c) powerful radio galaxies. This proposal leads to quantitative tests, which are encouraging so far. Quantitative models for transport and interaction appear to be consistent with the data. Li, Be, B are secondary in cosmic rays, as are many of the odd-Z elements, as well as the sub-Fe elements. At very low energies, cosmic ray particles are subject to ionization losses, which produce a steep low energy cutoff; all particles below the cutoff are moved into the thermal material population, and the particles above it remain as cosmic rays. This then changes the chemical abundances in the interstellar medium, and is a dominant process for many isotopes of Li, Be, B. With a quantitative theory for the origin of cosmic rays proposed, it appears worthwhile to search for yet better spallation cross sections, especially near threshold. With such an improved set of cross sections, the theory of the interstellar medium and its chemical abundances, both in thermal and in energetic particles, could be taken a large step forward. (author)

  6. Temporal evolution of 36Cl abundances in the Great Lakes

    The observed 36Cl isotopic abundance in Great Lakes water decreases from west to east, with the highest 36Cl/Cl ratio of 1332 × 10−15 in Lake Superior and the lowest 36Cl/Cl ratio of 151 × 10−15 in Lake Erie, whereas the 36Cl concentration (36Cl atoms/L) is lowest in Lake Superior and higher in the other Great Lakes. The 36Cl concentration in Lake Superior is much higher than expected from normal atmospheric deposition over the basin, consistent with deposition of nuclear bomb-produced 36Cl during 1952–1964. A conservative mass-balance model constrained by hydrological parameters and available 36Cl fluence measurements predicts the 36Cl abundances in the Great Lakes from 1945 to 2015, in excellent agreement with available data for Lakes Superior, Michigan, and Huron, but the model underestimates 36Cl abundances for Lakes Erie and Ontario. However, assuming that 36Cl demonstrates non-conservative behavior and is significantly retained in the drainage basins, a model incorporating a delayed input parameter successfully predicts observed 36Cl concentrations in all of the Great Lakes. - Highlights: • 36Cl/Cl ratios are the highest in Lake Superior and the lowest in Lake Erie. • 36Cl concentrations in the Great Lakes are much higher than expected natural values. • Conservative 36Cl model underestimates observed values in Lakes Erie and Ontario. • Large fraction of 36Cl atoms deposited on the watersheds are retained for decades

  7. Achievements in testing of the MGA and FRAM isotopic software codes under the DOE/NNSA-IRSN cooperation of gamma-ray isotopic measurement systems

    Vo, Duc [Los Alamos National Laboratory; Wang, Tzu - Fang [LLNL; Funk, Pierre [IRSN; Weber, Anne - Laure [IRSN; Pepin, Nicolas [IRSN; Karcher, Anna [IRSN

    2009-01-01

    DOE/NNSA and IRSN collaborated on a study of gamma-ray instruments and analysis methods used to perform isotopic measurements of special nuclear materials. The two agencies agreed to collaborate on the project in response to inconsistencies that were found in the various versions of software and hardware used to determine the isotopic abundances of uranium and plutonium. IRSN used software developed internally to test the MGA and FRAM isotopic analysis codes for criteria used to stop data acquisition. The stop-criterion test revealed several unusual behaviors in both the MGA and FRAM software codes.

  8. Earth and space science of noble gas isotopes

    This review described earth and space science concerning environments of formation and evolution of earth and meteorites by analyzing the elemental and isotopic abundance of noble gasses. The component and names of noble gasses were defined as to cosmic (solar system) abundance, trapped (primordial) component, nucleogenic component and atmospheric component. The nucleogenic component was originated from nuclear reaction and was thus radiogenic, fissiogenic and spallogenic. The abundance of those gasses was classified to be solar, planetary and atmospheric. Origins and abundance were described for He, Ne, Ar, Kr and Xe. Noble gasses have been important as the absolute, cosmic ray and solar chronometers in the chronology. As for earth science, He-Ar and He-Ne systematics, importance of Xe in the mantle and isotopic abundance of the gasses in the past mantle were described together with the relationships between the release of the gasses from the dislocation and earthquake and between the unusual concentration of Ne and origin of tektite. Space science: ''Q'' was measured by treatment of meteorites with acids and showing mainly their content of heavy noble gasses. Q studies suggested the presence of out-solar meteorites. The relations of Xe-HL, Xe-S and Kr-S with out-solar materials were described. The origin of meteorite diamond was discussed based on author's experiments. (K.H.). 53 refs

  9. Climate and local abundance in freshwater fishes.

    Knouft, Jason H; Anthony, Melissa M

    2016-06-01

    Identifying factors regulating variation in numbers of individuals among populations across a species' distribution is a fundamental goal in ecology. A common prediction, often referred to as the abundant-centre hypothesis, suggests that abundance is highest near the centre of a species' range. However, because of the primary focus on the geographical position of a population, this framework provides little insight into the environmental factors regulating local abundance. While range-wide variation in population abundance associated with environmental conditions has been investigated in terrestrial species, the relationship between climate and local abundance in freshwater taxa across species' distributions is not well understood. We used GIS-based temperature and precipitation data to determine the relationships between climatic conditions and range-wide variation in local abundance for 19 species of North American freshwater fishes. Climate predicted a portion of the variation in local abundance among populations for 18 species. In addition, the relationship between climatic conditions and local abundance varied among species, which is expected as lineages partition the environment across geographical space. The influence of local habitat quality on species persistence is well documented; however, our results also indicate the importance of climate in regulating population sizes across a species geographical range, even in aquatic taxa. PMID:27429769

  10. Taking species abundance distributions beyond individuals

    Morlon, Helene; White, Ethan P.; Etienne, Rampal S.; Green, Jessica L.; Ostling, Annette; Alonso, David; Enquist, Brian J.; He, Fangliang; Hurlbert, Allen; Magurran, Anne E.; Maurer, Brian A.; McGill, Brian J.; Olff, Han; Storch, David; Zillio, Tommaso; Chave, Jérôme

    2009-01-01

    The species abundance distribution (SAD) is one of the few universal patterns in ecology. Research on this fundamental distribution has primarily focused on the study of numerical counts, irrespective of the traits of individuals. Here we show that considering a set of Generalized Species Abundance

  11. Methanol abundance in low mass protostars

    Maret, S

    2004-01-01

    Methanol lines observations of a sample of low mass Class 0 protostars are presented. Using a 1D radiative transfer model, I show that several protostars have large abundance jumps in the inner hot and dense region of envelopes, probably because of thermal grain mantle evaporation. These abundances are compared with a grain surface chemistry model.

  12. Analysis of the site-specific carbon isotope composition of propane by gas source isotope ratio mass spectrometer

    Piasecki, Alison; Sessions, Alex; Lawson, Michael; Ferreira, A. A.; Neto, E. V. Santos; Eiler, John M.

    2016-09-01

    Site-specific isotope ratio measurements potentially provide valuable information about the formation and degradation of complex molecules-information that is lost in conventional bulk isotopic measurements. Here we discuss the background and possible applications of such measurements, and present a technique for studying the site-specific carbon isotope composition of propane at natural abundance based on mass spectrometric analysis of the intact propane molecule and its fragment ions. We demonstrate the feasibility of this approach through measurements of mixtures of natural propane and propane synthesized with site-specific 13C enrichment, and we document the limits of precision of our technique. We show that mass balance calculations of the bulk δ13C of propane based on our site-specific measurements is generally consistent with independent constraints on bulk δ13C. We further demonstrate the accuracy of the technique, and illustrate one of its simpler applications by documenting the site-specific carbon isotope signature associated with gas phase diffusion of propane, confirming that our measurements conform to the predictions of the kinetic theory of gases. This method can be applied to propane samples of moderate size (tens of micromoles) isolated from natural gases. Thus, it provides a means of studying the site-specific stable isotope systematics of propane at natural isotope abundances on sample sizes that are readily recovered from many natural environments. This method may also serve as a model for future techniques that apply high-resolution mass spectrometry to study the site-specific isotopic distributions of larger organic molecules, with potential applications to biosynthesis, forensics and other geochemical subjects.

  13. Bimodal abundances in the energetic particles of solar and interplanetary origin

    Reames, Donald V.

    1988-01-01

    This letter reports the first results from an examination of the daily-averaged abundances of the elements from H through Fe as well as electrons and isotopes of He in energetic particles observed in interplanetary space by the ISEE 3 spacecraft over an 8.5 yr period. The abundances of heavy elements such as Fe/O show, for the first time, clear evidence of the presence of two distinct populations of particles. Earlier observations could be interpreted as extreme variations within a single population. The population with enhanced Fe/O shows correlated enhancements in He-3/He-4, p/e, and He/H. This population is consistent with material that has been processed to high temperatures in the impulsively heated regions of solar flares. The second population, with more normal abundances, is probably accelerated from ambient material by coronal and interplanetary shocks.

  14. Ion-molecule calculation of the abundance ratio of CCD to CCH in dense interstellar clouds

    Laboratory measurements and calculations have been performed to determine the abundance ratio of the deuterated ethynyl radical (CCD) to the normal radical (CCH) which can be achieved in dense interstellar clouds via isotopic fractionation in the C2H2(+) (HD)=C2HD(+)(H2) system of reactions. According to this limited treatment, the CCD/CCH abundance ratio which can be attained is in the range 0.02-0.03 for the Orion molecular cloud and 0.0l-0.02 for TMC-1. These ranges of numbers are in reasonable agreement with the observed values in Orion and TMC-1. However, the analysis of the CCD/CCH abundance ratio is complicated via the presence of competing fractionation mechanisms, especially in the low-temperature source TMC-1. 28 references

  15. Solar Energetic Particles: Sampling Coronal Abundances

    Reames, Donald V.

    1998-05-01

    In the large solar energetic particle (SEP) events, coronal mass ejections (CMEs) drive shock waves out through the corona that accelerate elements of the ambient material to MeV energies in a fairly democratic, temperature-independent manner. These events provide the most complete source of information on element abundances in the corona. Relative abundances of 22 elements from H through Zn display the well-known dependence on the first ionization potential (FIP) that distinguishes coronal and photospheric material. For most elements, the main abundance variations depend upon the gyrofrequency, and hence on the charge-to-mass ratio, Q/A, of the ion. Abundance variations in the dominant species, H and He, are not Q/A dependent, presumably because of non-linear wave-particle interactions of H and He during acceleration. Impulsive flares provide a different sample of material that confirms the Ne:Mg:Si and He/C abundances in the corona.

  16. Biological isotopy. Introduction to the isotopic effects and to their applications in biology

    Since their discovery in the beginning of the 20. century, the study of stable isotopes has considerably developed. This domain, which remained limited in its applications until the 1990's, has become particularly important thereafter thanks to its practical applications and in particular to its economical impacts. Many techniques used in fraud control, in drugs use control, in selection of high-yield plants etc are based on isotopic abundance measurements. This reference book gives a synthesis of our actual knowledge on the use of stable isotopes and of isotope fractionation in biology. It presents the basic notions of isotopic biochemistry and explains the origin of the isotopic effects. The application principles of these effects to metabolism, to organisms physiology, to environmental biology etc are explained and detailed using examples and exercises. The first chapters present the basic knowledge which defines, from a mathematical point-of-view, the isotopic effects of chemical reactions or of physical processes taking place in biology. The measurements principle of natural isotopes abundance is then synthesised. Finally, all these notions are applied at different scales: enzymes, physiology, metabolism, environment, ecosystems and fraud crackdown. (J.S.)

  17. Operational models of the cryogenic distillation column for 13C isotope

    Full text: There are many domains of life, techniques, industry, environmental analysis and protection, where the heavier isotopes are useful. The predominant isotope of the carbon is (12C), with the natural abundance of 98.9%, but as tracer in many application is required the 13C isotope, initially with the concentration of 1.1%. For industrial output and higher concentration, the method of the cryogenic distillation is a proper solution. This method is a special application, with particular features in distillation and isotope separation. Unlike the air or natural gas cryogenic distillation, the inflow of the material with natural abundance in a heavy isotope has a minor influence on the concentration evolution, but there are many other significant factors. The evolution of the isotope enrichment in time and space may be known only using mathematical models. Practically, no samples in various points of the distillation plant are possible. With these aspects in mind, the necessity of mathematical models is justified. In order to validate the described mathematical model of the cryogenic distillation column structure, the authors use the data from literature, referring to a similar equipment used for 13C and 18O isotope separation. The simulation strategy is to represent the time-evolution of the 13C isotope ratio in three 'points', namely: the top side of the column (stripping section, 'waste'-zone), the middle of the rectifying zone and the bottom side of the column (z=Zc) and to determine the steady-state values. (author)

  18. THE NITROGEN ISOTOPIC COMPOSITION OF METEORITIC HCN

    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.

  19. Separation of uranium isotopes by gas centrifugation

    The uranium isotope enrichment is studied by means of the countercurrent gas centrifuge driven by thermal convection. A description is given of (a) the transfer and purification of the uranium hexafluoride used as process gas in the present investigation; (b) the countercurrent centrifuge ZG3; (c) the system designed for the introduction and extraction of the process gas from the centrifuge; (d) the measurement of the process gas flow rate through the centrifuge; (e) the determination of the uranium isotopic abundance by mass spectrometry; (f) the operation and mechanical behavior of the centrifuge and (g) the isotope separation experiments, performed, respectively, at total reflux and with production of enriched material. The results from the separation experiments at total reflux are discussed in terms of the enrichment factor variation with the magnitude and flow profile of the countercurrent given by the temperature difference between the rotor covers. As far as the separation experiments with production are concerned, the discussion of their results is presented through the variation of the enrichment factor as a function of the flow rate, the observed asymmetry of the process and the calculated separative power of the centrifuge. (Author)

  20. Matrix effects in laser ablation molecular isotopic spectrometry

    Recently, it has been shown that laser-induced breakdown spectroscopy (LIBS) can be used for the detection of isotopes of elements via isotopic shifts in diatomic species in a technique known as laser ablation molecular isotopic spectrometry (LAMIS). While LAMIS works quite well for isotopic analysis of pure compounds under optimal conditions, it is desirable for it to be applicable for a variety of compounds and matrices. However, the LIBS plasma emission associated with LAMIS depends on several parameters, including the applied electric field of the laser pulse, the physical properties of the material being investigated, and the presence of additional elements other than the element of interest. In this paper, we address some of the pitfalls arising from these dependencies when using LAMIS for the determination of the relative isotopic abundance of boron-containing materials with varying chemical matrices. - Highlights: • LAMIS usually determines isotopic composition of boron compounds within 3 percent. • LaBO3 and some boron-containing mixtures yield inaccurate LAMIS results. • Higher laser energy reduces variability but does not remedy poor LAMIS outcomes

  1. Stable isotopes in leaf water of terrestrial plants.

    Cernusak, Lucas A; Barbour, Margaret M; Arndt, Stefan K; Cheesman, Alexander W; English, Nathan B; Feild, Taylor S; Helliker, Brent R; Holloway-Phillips, Meisha M; Holtum, Joseph A M; Kahmen, Ansgar; McInerney, Francesca A; Munksgaard, Niels C; Simonin, Kevin A; Song, Xin; Stuart-Williams, Hilary; West, Jason B; Farquhar, Graham D

    2016-05-01

    Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ(18) O and δ(2) H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water. PMID:26715126

  2. Aberrant water homeostasis detected by stable isotope analysis.

    Shannon P O'Grady

    Full Text Available While isotopes are frequently used as tracers in investigations of disease physiology (i.e., 14C labeled glucose, few studies have examined the impact that disease, and disease-related alterations in metabolism, may have on stable isotope ratios at natural abundance levels. The isotopic composition of body water is heavily influenced by water metabolism and dietary patterns and may provide a platform for disease detection. By utilizing a model of streptozotocin (STZ-induced diabetes as an index case of aberrant water homeostasis, we demonstrate that untreated diabetes mellitus results in distinct combinations, or signatures, of the hydrogen (delta2H and oxygen (delta18O isotope ratios in body water. Additionally, we show that the delta2H and delta18O values of body water are correlated with increased water flux, suggesting altered blood osmolality, due to hyperglycemia, as the mechanism behind this correlation. Further, we present a mathematical model describing the impact of water flux on the isotopic composition of body water and compare model predicted values with actual values. These data highlight the importance of factors such as water flux and energy expenditure on predictive models of body water and additionally provide a framework for using naturally occurring stable isotope ratios to monitor diseases that impact water homeostasis.

  3. Stable isotope techniques in plant water sources:a review

    2010-01-01

    The stable hydrogen and oxygen isotopes widely exist in various kinds of natural water.Plants have to cope with various water sources:rainwater,soil water,groundwater,sea water,and mixtures.These are usually characterized by different isotopic signatures (18O/16O and D/H ratios).Because there are relative abundance variations in water,and plant roots do not discriminate against specific water isotopes during water uptake,hydrogen and oxygen stable isotope ratios of water within plants provide new information on water sources,interactions between plant species and water use patterns under natural conditions.At present,the measurement of δD,δ18O composition of various potential water sources and stem water has become significant means to identify plant water sources.Based on previous studies,this review highlights recent advances such as theory basis,methodology,as well as different spatial and temporal scales,and existed questions and prospects.Stable isotope techniques for estimating plant water sources have provided valuable tools for conducting basic and applied research.Future studies emphasize the modification of preparing methods,isotope technique combined with other measurements,and aerial organs of plant water source should be en-couraged.

  4. Isotope determination of sulfur by mass spectrometry in soil samples

    Alexssandra Luiza Rodrigues Molina Rossete

    2012-12-01

    Full Text Available Sulphur plays an essential role in plants and is one of the main nutrients in several metabolic processes. It has four stable isotopes (32S, 33S, 34S, and 36S with a natural abundance of 95.00, 0.76, 4.22, and 0.014 in atom %, respectively. A method for isotopic determination of S by isotope-ratio mass spectrometry (IRMS in soil samples is proposed. The procedure involves the oxidation of organic S to sulphate (S-SO4(2-, which was determined by dry combustion with alkaline oxidizing agents. The total S-SO4(2- concentration was determined by turbidimetry and the results showed that the conversion process was adequate. To produce gaseous SO2 gas, BaSO4 was thermally decomposed in a vacuum system at 900 ºC in the presence of NaPO3. The isotope determination of S (atom % 34S atoms was carried out by isotope ratio mass spectrometry (IRMS. In this work, the labeled material (K2(34SO4 was used to validate the method of isotopic determination of S; the results were precise and accurate, showing the viability of the proposed method.

  5. Matrix effects in laser ablation molecular isotopic spectrometry

    Brown, Staci, E-mail: staci.brown@cepast.famu.edu [Department of Physics, Florida A and M University, 2077 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); Ford, Alan, E-mail: alan.ford@alakaidefense.com [Alakai Defense Systems, 197 Replacement Ave, Suite 102, Fort Leonard Wood, MO 65473 (United States); Akpovo, Charlemagne C., E-mail: charlemagne.akpovo@cepast.famu.edu [Department of Physics, Florida A and M University, 2077 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); Martinez, Jorge, E-mail: jmartinez@cepast.famu.edu [Department of Physics, Florida A and M University, 2077 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); Johnson, Lewis, E-mail: lewis@cepast.famu.edu [Department of Physics, Florida A and M University, 2077 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States)

    2014-11-01

    Recently, it has been shown that laser-induced breakdown spectroscopy (LIBS) can be used for the detection of isotopes of elements via isotopic shifts in diatomic species in a technique known as laser ablation molecular isotopic spectrometry (LAMIS). While LAMIS works quite well for isotopic analysis of pure compounds under optimal conditions, it is desirable for it to be applicable for a variety of compounds and matrices. However, the LIBS plasma emission associated with LAMIS depends on several parameters, including the applied electric field of the laser pulse, the physical properties of the material being investigated, and the presence of additional elements other than the element of interest. In this paper, we address some of the pitfalls arising from these dependencies when using LAMIS for the determination of the relative isotopic abundance of boron-containing materials with varying chemical matrices. - Highlights: • LAMIS usually determines isotopic composition of boron compounds within 3 percent. • LaBO{sub 3} and some boron-containing mixtures yield inaccurate LAMIS results. • Higher laser energy reduces variability but does not remedy poor LAMIS outcomes.

  6. Evidence from carbon isotope measurements for diverse origins of sedimentary hydrocarbons

    Freeman, K. H.; Hayes, J. M.; Trendel, J. M.; Albrecht, P.

    1990-01-01

    The organic matter found in sedimentary rocks must derive from many sources; not only from ancient primary producers but also from consumers and secondary producers. In all of these organisms, isotope effects can affect the abundance and distribution of 13C in metabolites. Here, by using an improved form of a previously described technique in which the effluent of a gas chromatograph is continuously analysed isotopically, we report evidence of the diverse origins of sedimentary organic matter. The record of 13C abundances in sedimentary carbonate and total organic carbon can be interpreted in terms of variations in the global carbon cycle. Our results demonstrate, however, that isotope variations within sedimentary organic mixtures substantially exceed those observed between samples of total organic carbon. Resolution of isotope variations at the molecular level offers a new and convenient means of refining views both of localized palaeoenvironments and of control mechanisms within the global carbon cycle.

  7. Distribution and carbon isotope patterns of diterpenoids and triterpenoids in modern temperate C3 trees and their geochemical significance

    Diefendorf, Aaron F.; Freeman, Katherine H.; Wing, Scott L.

    2012-05-01

    Tricyclic diterpenoids and pentacyclic triterpenoids are nearly exclusively produced by gymnosperms and angiosperms, respectively. Even though both classes of terpenoids have long been recognized as plant biomarkers, their potential use as phylogenetically specific δ13C proxies remains largely unexplored. Little is known of how terpenoid abundance and carbon isotope composition vary either with plant phylogenetic position, functional group, or during synthesis. Here, we report terpenoid abundances and isotopic data for 44 tree species in 21 families, representing both angiosperms and gymnosperms, and both deciduous and evergreen leaf habits. Di- and triterpenoid abundances are significantly higher in evergreens compared to deciduous species, reflecting differences in growth strategies and increased chemical investment in longer-lived leaves. Carbon isotope abundances of terpenoid lipids are similar to leaf tissues, indicating biosynthetic isotope effects are small for both the MVA (-0.4‰) and MEP (-0.6‰) pathways. Leaf and molecular isotopic patterns for modern plants are consistent with observations of amber, resins and plant biomarkers in ancient sediments. The δ13C values of ancient diterpenoids are higher than triterpenoids by 2-5‰, consistent with observed isotopic differences between gymnosperms and angiosperms leaves, and support the relatively small lipid biosynthetic effects reported here. All other factors being equal, evergreen plants will dominate the abundance of terpenoids contributed to soils, sediments and ancient archives, with similar inputs estimated for angiosperm and gymnosperm trees when scaled by litter flux.

  8. Transportation of medical isotopes

    A Draft Technical Information Document (HNF-1855) is being prepared to evaluate proposed interim tritium and medical isotope production at the Fast Flux Test Facility (FFTF). This assessment examines the potential health and safety impacts of transportation operations associated with the production of medical isotopes. Incident-free and accidental impacts are assessed using bounding source terms for the shipment of nonradiological target materials to the Hanford Site, the shipment of irradiated targets from the FFTF to the 325 Building, and the shipment of medical isotope products from the 325 Building to medical distributors. The health and safety consequences to workers and the public from the incident-free transportation of targets and isotope products would be within acceptable levels. For transportation accidents, risks to works and the public also would be within acceptable levels. This assessment is based on best information available at this time. As the medical isotope program matures, this analysis will be revised, if necessary, to support development of a final revision to the Technical Information Document

  9. Separation of sulfur isotopes

    DeWitt, Robert; Jepson, Bernhart E.; Schwind, Roger A.

    1976-06-22

    Sulfur isotopes are continuously separated and enriched using a closed loop reflux system wherein sulfur dioxide (SO.sub.2) is reacted with sodium hydroxide (NaOH) or the like to form sodium hydrogen sulfite (NaHSO.sub.3). Heavier sulfur isotopes are preferentially attracted to the NaHSO.sub.3, and subsequently reacted with sulfuric acid (H.sub.2 SO.sub.4) forming sodium hydrogen sulfate (NaHSO.sub.4) and SO.sub.2 gas which contains increased concentrations of the heavier sulfur isotopes. This heavy isotope enriched SO.sub.2 gas is subsequently separated and the NaHSO.sub.4 is reacted with NaOH to form sodium sulfate (Na.sub.2 SO.sub.4) which is subsequently decomposed in an electrodialysis unit to form the NaOH and H.sub.2 SO.sub.4 components which are used in the aforesaid reactions thereby effecting sulfur isotope separation and enrichment without objectionable loss of feed materials.

  10. Silicon abundances in population I giants

    Boehm-Vitense, Erika

    1992-01-01

    Silicon to carbon abundance ratios for population I giants were determined from emission lines originating in the transition layers between stellar chromospheres and coronae. For effective temperatures larger than 6200 K we find a group of stars with increased silicon to carbon but normal nitrogen to carbon abundance ratios. These stars are presumably descendents from Ap stars with increased surface silicon to carbon abundance ratios. For G stars this anomaly disappears as is to be expected due to the increased depth of the convection zone and therefore deeper mixing which dilutes the surface overabundances. The disappearance of the abundance anomalies proves that the anomalous abundances observed for the F giants are indeed only a surface phenomenon. It also proves that the same holds for their progenitors, the Ap and Am stars, as has been generally believed. Unexplained is the increased silicon to carbon abundance ratio observed for several stars cooler than 5100 L. RS CVn and related stars do not show this increased abundance ratio. There are also some giants which appear to be enriched in carbon, perhaps due to a helium flash with some mixing if the star is a clump star.

  11. Molecular Paleohydrology: Interpreting the Hydrogen- Isotopic Composition of Lipid Biomarkers from Photosynthesizing Organisms

    D. Sachse; Billault, I.; G. J. Bowen; CHIKARAISHI, Y.; Dawson, T E; Feakins, S.J.; Freeman, Katherine; Magill, C.R.; McInerney, F.A.; Meer, M.T.J. van der; Polissar, P.; Robins, R.J.; Sachs, J.P.; Schmidt, H.L.; Sessions, A.L.

    2012-01-01

    Hydrogen-isotopic abundances of lipid biomarkers are emerging as important proxies in the study of ancient environments and ecosystems. A decade ago, pioneering studies made use of new analytical methods and demonstrated that the hydrogen-isotopic composition of individual lipids from aquatic and terrestrial organisms can be related to the composition of their growth (i.e., environmental) water. Subsequently, compound-specific deuterium/hydrogen (D/H) ratios of sedimentary biomarkers have bee...

  12. Si isotopes in tropical rivers as a proxy of the continental silicon cycle

    Hughes, Harold

    2011-01-01

    Silicon (Si) is one of the most abundant elements in the dissolved phase in rivers and is a key nu-trient in riverine and marine ecosystems. The continental cycle of Si is complex and involves interactions with many secondary reservoirs such as clay minerals and biogenic silica (BSi), making the Si fluxes hard to constrain. Stable isotopes provide a way to trace and describe element cycling. The natural isotopic fractionations that accompany the transfer of the element from one reservoir to a...

  13. Water enriched in the rare stable isotopes: Preparation, measurement and applications

    Faghihi, Vahideh

    2016-01-01

    The subject of this thesis is water with increased abundances of the rare stable isotopes 2H and 18O (and to some extent also 17O). Such artificially enriched (or "labelled") waters are often used in biomedicine, for establishing the total amount of body water (and thus body composition) of humans and animals and also for measuring their energy expenditure. These non-evasive totally harmless techniques offer great advantages, however they require accurate and precise "isotope ratio" measureme...

  14. Perchlorate in the Great Lakes: isotopic composition and origin.

    Poghosyan, Armen; Sturchio, Neil C; Morrison, Candice G; Beloso, Abelardo D; Guan, Yunbin; Eiler, John M; Jackson, W Andrew; Hatzinger, Paul B

    2014-10-01

    Perchlorate is a persistent and mobile contaminant in the environment with both natural and anthropogenic sources. Stable isotope ratios of oxygen (δ(18)O, Δ(17)O) and chlorine (δ(37)Cl) along with the abundance of the radioactive isotope (36)Cl were used to trace perchlorate sources and behavior in the Laurentian Great Lakes. These lakes were selected for study as a likely repository of recent atmospheric perchlorate deposition. Perchlorate concentrations in the Great Lakes range from 0.05 to 0.13 μg per liter. δ(37)Cl values of perchlorate from the Great Lakes range from +3.0‰ (Lake Ontario) to +4.0‰ (Lake Superior), whereas δ(18)O values range from -4.1‰ (Lake Superior) to +4.0‰ (Lake Erie). Great Lakes perchlorate has mass-independent oxygen isotopic variations with positive Δ(17)O values (+1.6‰ to +2.7‰) divided into two distinct groups: Lake Superior (+2.7‰) and the other four lakes (∼+1.7‰). The stable isotopic results indicate that perchlorate in the Great Lakes is dominantly of natural origin, having isotopic composition resembling that measured for indigenous perchlorate from preindustrial groundwaters of the western USA. The (36)Cl/Cl ratio of perchlorate varies widely from 7.4 × 10(-12) (Lake Ontario) to 6.7 × 10(-11) (Lake Superior). These (36)ClO4(-) abundances are consistent with an atmospheric origin of perchlorate in the Great Lakes. The relatively high (36)ClO4(-) abundances in the larger lakes (Lakes Superior and Michigan) could be explained by the presence of (36)Cl-enriched perchlorate deposited during the period of elevated atmospheric (36)Cl activity following thermonuclear bomb tests in the Pacific Ocean. PMID:25171443

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

    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.

  16. Predicting the dynamics of protein abundance.

    Mehdi, Ahmed M; Patrick, Ralph; Bailey, Timothy L; Bodén, Mikael

    2014-05-01

    Protein synthesis is finely regulated across all organisms, from bacteria to humans, and its integrity underpins many important processes. Emerging evidence suggests that the dynamic range of protein abundance is greater than that observed at the transcript level. Technological breakthroughs now mean that sequencing-based measurement of mRNA levels is routine, but protocols for measuring protein abundance remain both complex and expensive. This paper introduces a Bayesian network that integrates transcriptomic and proteomic data to predict protein abundance and to model the effects of its determinants. We aim to use this model to follow a molecular response over time, from condition-specific data, in order to understand adaptation during processes such as the cell cycle. With microarray data now available for many conditions, the general utility of a protein abundance predictor is broad. Whereas most quantitative proteomics studies have focused on higher organisms, we developed a predictive model of protein abundance for both Saccharomyces cerevisiae and Schizosaccharomyces pombe to explore the latitude at the protein level. Our predictor primarily relies on mRNA level, mRNA-protein interaction, mRNA folding energy and half-life, and tRNA adaptation. The combination of key features, allowing for the low certainty and uneven coverage of experimental observations, gives comparatively minor but robust prediction accuracy. The model substantially improved the analysis of protein regulation during the cell cycle: predicted protein abundance identified twice as many cell-cycle-associated proteins as experimental mRNA levels. Predicted protein abundance was more dynamic than observed mRNA expression, agreeing with experimental protein abundance from a human cell line. We illustrate how the same model can be used to predict the folding energy of mRNA when protein abundance is available, lending credence to the emerging view that mRNA folding affects translation efficiency

  17. CUMULATIVE OXYGEN ABUNDANCES OF SPIRAL GALAXIES

    Studying the global evolution of spiral galaxies requires determining their overall chemical compositions. However, since spirals tend to possess gradients in their chemical compositions, determining their overall chemical abundances poses a challenge. In this study, the framework for a newly proposed method for determining the overall oxygen abundance of a disk is established. By separately integrating the absolute amounts of hydrogen and oxygen out to large radii, the cumulative oxygen abundance is shown to approach an asymptotic value. In this manner, a reliable account of the overall chemical state of a disk is revealed.

  18. Lithium Abundance of Metal-poor Stars

    Hua-Wei Zhang; Gang Zhao

    2003-01-01

    High-resolution, high signal-to-noise ratio spectra have been obtained for 32 metal-poor stars. The equivalent widths of Li λ6708A were measured and the lithium abundances were derived. The average lithium abundance of 21 stars on the lithium plateau is 2.33±0.02 dex. The Lithium plateau exhibits a marginal trend along metallicity, dA(Li)/d[Fe/H] = 0.12±0.06, and no clear trend with the effective temperature. The trend indicates that the abundance of lithium plateau may not be primordial and that a part of the lithium was produced in Galactic Chemical Evolution (GCE).

  19. Abundance analysis of HD 22920 spectra

    Khalack, Viktor

    2015-01-01

    The new spectropolarimetric observations of HD 22920 with ESPaDOnS at CFHT reveal a strong variability of its spectral line profiles with the phase of stellar rotation. We have obtained Teff = 13640 K, logg=3.72 for this star from the best fit of its nine Balmer line profiles. The respective model of stellar atmosphere was calculated to perform abundance analysis of HD 22920 using the spectra obtained for three different phases of stellar rotation. We have found that silicon and chromium abundances appear to be vertically stratified in the atmosphere of HD 22920. Meanwhile, silicon shows hints for a possible variability of vertical abundance stratification with rotational phase.

  20. Interlaboratory comparison for boron isotope ratio measurement with inductively coupled plasma-quadrupole mass spectrometer

    Boron isotope ratios were analyzed in seven domestic analytical labs for boric acid solutions with various compositions of boron isotope abundances, using an Inductively Coupled Plasma-Quadrupole Mass Spectrometer (ICP-QMS). Five sample solutions with different isotope abundances of 10B were prepared in the range of 10 to 20 % by mixing two boric acid solutions containing natural B and enriched 11B, respectively. Then, the 10B isotope abundances of each sample were certified by analyzing with thermal ionization mass spectrometry (TI-MS) according to ASTM-C791-04. Results obtained from each lab have indicated good coincidences with TI-MS results. Also, the relative standard deviations of results with ICP-QMS of seven analytical labs were 0.11 to 0.81 %. The measurement precision for ICP-QMS would be sufficient in terms of practical use, while taking into consideration a valid requirement required for verifying a depletion of the 10B isotope abundance in the PWR coolant, while this is greater than a nominal analytical error (relative value : 0.22 %) for TI-MS shown in ASTM-C791-04. (author)

  1. Laser isotope separation of {sup 176}Yb for medical applications

    Park, Hyunmin; Kwon, Duckhee; Cha, Yongho; Nam, Sungmo; Kim, Taksoo; Han, Jaemin; Rhee, Yongjoo; Jeong, Doyoung; Kim, Cheoljung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2006-07-15

    The radioisotope, {sup 177}Lu, is emerging as a promising isotope for a variety of medical applications such as cancer treatment. Enriched {sup 176}Yb can be used as a source material for the production of {sup 177}Lu in an atomic reactor. For these applications, we have developed a laser separation technology based on isotopic selective photoionization to enrich the stable {sup 176}Yb isotope. Our separation system consists of three dye lasers, a Yb vaporizer, and an ion-extraction system. Especially, we use a compact diode-pumped solid-state laser as the pumping source of the dye lasers. With the developed system, we succeeded in producing enriched {sup 176}Yb with an abundance of more than 97 %.

  2. Performance of isotope correlations for the estimate of 242Pu

    Full text: The lack of a gamma-ray signature from 242Pu represents an Achilles heel for many plutonium isotope abundance measurements made by high-resolution gamma spectrometry (HRGS). This holds in particular for plutonium materials containing a significant fraction of this isotope. The problem is partially solved through the application of isotope correlations estimating the relative abundance of 242Pu from relations to ratios of other plutonium isotopes measurable by HRGS. In the mid of the nineties a new type of isotope correlation had been proposed for LWR plutonium based on the following relation: 242Pu/239Pu = C0·[238Pu/239Pu]c1 · [240Pu/239Pu]c2 with recommended coefficients C0, C1 and C2 for PWR and BWR fuels, respectively. We have adopted this type of correlation for the routine analysis of safeguards samples in the Euratom On-Site Laboratories and in the Institute for Transuranium Elements. In order to cover the full range of plutonium materials received for analysis, the application of the above correlation has been also extended to AGR and Magnox-type of plutonium. The differing sets of coefficients C0, C1 and C2 approximating best the correlation for the additional types of materials were determined from a set of reference isotopic data. Since in many instances the origin and the type of the plutonium are not known a priori, criteria for categorization were established helping to select the appropriate isotope correlation. Parametric plots of the ratios 238Pu/239Pu versus 240Pu/239Pu generally allow to discern unambiguously Magnox, AGR and LWR plutonium, and to some extent also BWR and PWR plutonium, as long as a mixing of the respective plutonium materials has not occurred. With this kind of categorization implemented in the routine analysis the performance of the 242Pu estimate is substantially improving in most cases. Performance data for 242Pu in particular, and for plutonium isotope abundance measurements by HRGS in general, as derived from a

  3. Laser isotope separation techniques

    Having examined the high cost and low efficiency of existing processes for separating uranium isotopes in comparison with the encouraging assessed figures for laser separation processes and having considered the high potential separation factors which make possibly very low 235U concentrations in the depleted tailings from laser separation processes, the design of such a system is considered. There are two essential features. Firstly, only one isotope must absorb laser radiation, and secondly that absorption must lead to a successful physical or chemical separation of that species which has been optically excited. Such a scheme is illustrated and discussed. The important aspect of loss mechanisms which can depopulate the selectively excited levels and the ways in which isotopes may exhibit differences in optical absorption frequencies are considered. Examples are given to illustrate techniques used in the separation stage. Finally a summary is presented of those elements in which some enrichment has been achieved by optical techniques. (U.K.)

  4. Lithium isotope separation

    Published methods for 6Li-7Li lithium isotope separation have been reviewed. Future demand for 6Li, whose main use will be as a tritium breeder in blankets surrounding the core of DT fusion power reactors, is likely to exceed 5 Mg/a in the next century. The applicability of the various available methods to such a large scale production rate has been assessed. Research on improving the effectiveness of current lithium isotope separation processes has been carried out worldwide in several major areas during the past decade; these include two-phase chemical exchange systems, ion exchange resin chromatography, highly isotope-selective techniques like laser photoactivation and radiofrequency spectroscopy. Chemical exchange systems appear to offer good potential in the near term for 6Li enrichment

  5. Isotopic biogeochemistry of carbon in recent and fossil mammal bones and teeth from cold temperate areas

    The difference between 13C isotopic abundances in bone organic matter (collagen) and the mineral phase (carbonate hydroxylapatite) is used for the determination of the trophic level of the animal, especially on fossil samples. This difference is greater for herbivore mammals from cold and temperate areas than for South African herbivore mammals studied previously (0.84 ± 0.14% versus 0.68 ± 0.14% respectively). This larger value should be used in the interpretation of isotopic abundances of 13C in fossil mammals from temperate and arctic areas

  6. Abundances of presolar silicon carbide grains in primitive meteorites determined by NanoSIMS

    Davidson, Jemma; Busemann, Henner; Nittler, Larry R.; Alexander, Conel M. O.'D.; Orthous-Daunay, François-Régis; Franchi, Ian A.; Hoppe, Peter

    2014-08-01

    It has been suggested that the matrices of all chondrites are dominated by a common material with Ivuna-like (CI) abundances of volatiles, presolar grains and insoluble organic matter (IOM) (e.g., Alexander, 2005). However, matrix-normalized abundances of presolar silicon carbide (SiC) grains estimated from their noble gas components show significant variations in even the most primitive chondrites (Huss and Lewis, 1995; Huss et al., 2003), in contradiction to there being a common chondrite matrix material. Here we report presolar SiC abundances determined by NanoSIMS raster ion imaging of IOM extracted from primitive members of different meteorite groups. We show that presolar SiC abundance determinations are comparable between NanoSIMS instruments located at three different institutes, between residues prepared by different demineralization techniques, and between microtomed and non-microtomed samples. Our derived SiC abundances in CR chondrites are comparable to those found in the CI chondrites (∼30 ppm) and are much higher than previously determined by noble gas analyses. The revised higher CR SiC abundances are consistent with the CRs being amongst the most primitive chondrites in terms of the isotopic compositions and disordered nature of their organic matter. Similar abundances between CR1, CR2, and CR3 chondrites indicate aqueous alteration on the CR chondrite parent body has not progressively destroyed SiC grains in them. A low SiC abundance for the reduced CV3 RBT 04133 can be explained by parent body thermal metamorphism at an estimated temperature of ∼440 °C. Minor differences between primitive members of other meteorite classes, which did not experience such high temperatures, may be explained by prolonged oxidation at lower temperatures under which SiC grains formed outer layers of SiO2 that were not thermodynamically stable, leading to progressive degassing/destruction of SiC.

  7. High-precision mass spectrometric hydrogen isotope ratio measurements

    The analytical capabilities of mass spectrometric ion-current measurement systems are described on both a theoretical and a practical basis. From the theoretical standpoint, a signal-to-noise ratio (S/N) model that evaluated the fundamental sources of noise present in ion-current measurement systems was developed. Use of this model accurately predicted the performance (precision) for ion-current ratio measurements made by two isotope ratio mass spectrometers, one designed for carbon isotopic measurements, and the other designed for hydrogen isotopic measurements. Isotope ratio measurements differ from current-ratio measurements in that the observed ion-current ratio must be corrected to reflect the ratio of the ion currents due to the isotopic species of interest, which, for hydrogen isotope ratio mass spectrometry, are HD+ and H2+. Interfaces to these two ion currents are described in detail. To compensate for H3+ three measurement procedures, the two-standard calibration, the one-standard differential measurement with electronic H3+ compensation, and the two-standard differential measurement, are described. The one- and two-standard differential measurements were successfully used for measurement of isotopic abundances. Results of a collaborative investigation to validate the use of 18O in place of D as an isotopic label for total body water measurements are presented. In this research both 18O and D were administered simultaneously to several subjects. The weight of total body water of these subjects as measured by the dilution of D into the body water was in good agreement with the results of the 18O measurements. A brief description of the laboratory computer system is also given

  8. Cadmium isotope fractionation during adsorption to Mn-oxyhydroxide

    Wasylenki, L. E.; Swihart, J. W.

    2013-12-01

    The heavy metal cadmium is of interest both as a toxic contaminant in groundwater and as a critical nutrient for some marine diatoms [1], yet little is known about the biogeochemistry of this element. Horner et al. [2] suggested that Cd stable isotopes could potentially enable reconstruction of biological use of Cd in the marine realm: since cultured diatoms fractionate Cd isotopes [3], and ferromanganese crusts appear to incorporate a faithful record of deepwater Cd isotopes [2], depth profiles in such crusts may yield information about the extent of Cd assimilation of isotopically light Cd by diatoms over time. Although no work has yet been published regarding the use of stable isotopes to track reactive transport of Cd in contaminated aquifers, others have recently demonstrated the potential of isotopes to track reactions affecting the mobility of other toxic metals (e.g., [4]). With both of these potential applications in mind, we conducted two sets of experiments, at low and high ionic strength, in which Cd partially adsorbed to potassium birnessite. Our goals are to quantify the fractionations and to constrain the mechanisms governing Cd isotope behavior during adsorption to an environmentally abundant scavenger of Cd. Suspensions of synthetic birnessite were doped with various amounts of dissolved Cd2+ at pH ~8.3. Following reaction, the dissolved and adsorbed pools of Cd were separated by filtration, purified by anion exchange chromatography, and analyzed by multicollector ICP-MS using a double-spike routine. In all cases, lighter isotopes preferentially adsorbed to the birnessite particles. At low ionic strength (ILacan et al. (2006) Geochim. Cosmochim. Acta. 70, 5104. [4] Berna et al. (2010) Env. Sci. & Tech. 44, 1043.

  9. Isotopes in condensed matter

    Plekhanov, Vladimir G. [Computer Science College, Tallinn (Estonia). Mathematics and Physics Dept.

    2013-07-01

    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.

  10. Isotopes in Condensed Matter

    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. Environmental isotope survey

    Work was initiated on the 1st of September 1971 with the objective of finding out how best to use environmental isotopes in the interpretation of the hydrology, particularly subsurface hydrology, of Cyprus through a sparse reconnaissance sampling of all the major aquifers and springs covering the whole island. The distribution of sampling was such that the survey in itself could assist in clarifying particular hydrogeologic problems, provide a better understanding of the water systems of the island, establish a general environmental isotope - framework of the hydrologic regimen of Cyprus as well as to provide the basis for specific, more detailed, studies to be undertaken subsequently

  12. Climate and isotopic tracers

    The applications of natural radioactivity and isotopic measurements in the sciences concerning Earth and its atmosphere, are numerous: carbon 14 dating with the Tandetron apparatus at the Cea, measurement of oxygen 18 in coral or sediment limestone for the determination of ocean temperature and salinity, carbon 14 dating of corals for the determination of sea level variations, deuterium content in polar ice-cap leads to temperature variations determination; isotopic measurements also enable the determination of present climate features such as global warming, oceanic general circulation

  13. Zinc isotope anomalies

    The Zn isotope composition in refractory-element-rich inclusions of the Allende meteorite are determined. Typical inclusions contain normal Zn. A unique inclusion of the Allende meteorite shows an excess for Zn-66 of 16.7 + or - 3.7 eu (1 eu = 0.01 percent) and a deficit for Zn-70 of 21 + or - 13 eu. These results indicate the preservation of exotic components even for volatile elements in this inclusion. The observed excess Zn-66 correlates with excesses for the neutron-rich isotopes of Ca-48, Ti-50, Cr-54, and Fe-58 in the same inclusion. 32 refs

  14. Stable Isotope Group 1983 progress report

    The work of the Stable Isotope Group of the Institute of Nuclear Sciences in the fields of isotope geology, isotope hydrology, geochronology, isotope biology and related fields, and mass spectrometer instrumentation, during 1983, is described

  15. Stable Isotope Group 1982 progress report

    The work of the Stable Isotope Group of the Institute of Nuclear Sciences during 1982, in the fields of isotope geology, isotope hydrology, geochronology, isotope biology and mass spectrometer instrumentation, is described

  16. Iron abundance in the atmosphere of Arcturus

    Sheminova, V A

    2015-01-01

    Abundance of iron in the atmosphere of Arcturus has been determined from the profiles or regions of the profiles of the weak lines sensitive to iron abundance. The selected lines of Fe I and Fe II were synthesized with the MARCS theoretical models of the atmosphere. From the observed profiles of lines available with a high spectral resolution in the atlas by Hinkle and Wallace (2005), the values of the iron abundance $A = 6.95 \\pm 0.03$ and the radial-tangential macroturbulent velocity $5.6 \\pm 0.2$ km/s were obtained for Arcturus. The same physical quantities were found for the Sun as a star; they are $7.42 \\pm 0.02$ and $3.4 \\pm 0.3$ km/s, respectively. For Arcturus, the iron abundance relative to the solar one was determined with the differential method as [Fe/H] $=-0.48 \\pm 0.02$.

  17. Chemical abundance analysis of 19 barium stars

    Yang, G C; Spite, M; Chen, Y Q; Zhao, G; Zhang, B; Liu, G Q; Liu, Y J; Liu, N; Deng, L C; Spite, F; Hill, V; Zhang, C X

    2016-01-01

    We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. The chemical abundances of the sample stars were obtained from an LTE, plane-parallel and line-blanketed atmospheric model by inputting the atmospheric parameters (effective temperatures, surface gravities, metallicity and microturbulent velocity) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their light elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn and Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-ca...

  18. SWFSC/MMTD: Vaquita Abundance Survey 1997

    National Oceanic and Atmospheric Administration, Department of Commerce — In 1997, the Southwest Fisheries Science Center (SWFSC) conducted a survey designed to estimate the abundance of vaquita, the Gulf of California harbor porpoise...

  19. Chinook Abundance - Linear Features [ds181

    California Department of Resources — The dataset 'ds181_Chinook_ln' is a product of the CalFish Adult Salmonid Abundance Database. Data in this shapefile are collected from stream sections or reaches...

  20. Testing Relationships between Energy and Vertebrate Abundance

    Understanding what drives variation in the abundance of organisms is fundamental to evolutionary ecology and wildlife management. Yet despite its importance, there is still great uncertainty about the main factors influencing variation in vertebrate abundance across taxa. We believe valuable knowledge and increased predictive power could be gained by taking into account both the intrinsic factors of species and the extrinsic factors related to environmental surroundings in the commonly cited RQ model, which provides a simple conceptual framework valid at both the interspecific and the intraspecific scales. Approaches comparing studies undertaken at different spatial and taxonomic scales could be key to our ability to better predict abundance, and thanks to the increased availability of population size data, global geographic datasets, and improved comparative methods, there might be unprecedented opportunities to (1) gain a greater understanding of vertebrate abundance patterns and (2) test existing theories on free-ranging animals.

  1. Primordial Deuterium Abundance and Cosmic Baryon Density

    Hogan, Craig J.

    1994-01-01

    The comparison of cosmic abundances of the light elements with the density of baryonic stars and gas in the universe today provides a critical test of big bang theory and a powerful probe of the nature of dark matter. A new technique allows determination of cosmic deuterium abundances in quasar absorption clouds at large redshift, allowing a new test of big bang homogeneity in diverse, very distant systems. The first results of these studies are summarized, along with their implications. The ...

  2. Unprecedented accurate abundances: signatures of other Earths?

    Melendez, J.; Asplund, M.; Gustafsson, B.; Yong, D.; Ramirez, I.

    2009-01-01

    For more than 140 years the chemical composition of our Sun has been considered typical of solar-type stars. Our highly differential elemental abundance analysis of unprecedented accuracy (~0.01 dex) of the Sun relative to solar twins, shows that the Sun has a peculiar chemical composition with a ~20% depletion of refractory elements relative to the volatile elements in comparison with solar twins. The abundance differences correlate strongly with the condensation temperatures of the elements...

  3. Estimating whale abundance using sparse hydrophone arrays

    Harris, Danielle Veronica

    2012-01-01

    Passive acoustic monitoring has been used to investigate many aspects of marine mammal ecology, although methods to estimate absolute abundance and density using acoustic data have only been developed in recent years. The instrument configuration in an acoustic survey determines which abundance estimation methods can be used. Sparsely distributed arrays of instruments are useful because wide geographic areas can be covered. However, instrument spacing in sparse arrays is such that the same...

  4. Spatial scaling of species abundance distributions

    Borda-de-Água, Luís; Borges, Paulo A. V.; Hubbell, Stephen P.; Pereira, Henrique M

    2012-01-01

    Copyright © 2012 The Authors. Ecography © 2012 Nordic Society Oikos. Species abundance distributions are an essential tool in describing the biodiversity of ecological communities. We now know that their shape changes as a function of the size of area sampled. Here we analyze the scaling properties of species abundance distributions by using the moments of the logarithmically transformed number of individuals. We find that the moments as a function of area size are well fitted by power law...

  5. How selection structures species abundance distributions

    Magurran, A.E; Henderson, P. A.

    2012-01-01

    How do species divide resources to produce the characteristic species abundance distributions seen in nature? One way to resolve this problem is to examine how the biomass (or capacity) of the spatial guilds that combine to produce an abundance distribution is allocated among species. Here we argue that selection on body size varies across guilds occupying spatially distinct habitats. Using an exceptionally well-characterized estuarine fish community, we show that biomass is concentrated in l...

  6. Solar Models with New Low Metal Abundances

    Yang, Wuming

    2016-04-01

    In the past decade, the photospheric abundances of the Sun had been revised several times by many observers. The standard solar models constructed with the new low-metal abundances disagree with helioseismic results and detected neutrino fluxes. The solar model problem has puzzled some stellar physicists for more than 10 years. Rotation, enhanced diffusion, convection overshoot, and magnetic fields are used to reconcile the new abundances with helioseismology. The too low helium subsurface abundance in enhanced diffusion models can be improved by the mixing caused by rotation and magnetic fields. The problem of the depth of the convective zone in rotating models can be resolved by convection overshoot. Consequently, the Asplund–Grevesse–Sauval rotation model including overshooting (AGSR) reproduces the seismically inferred sound-speed and density profiles and the convection zone depth as well as the Grevesse & Sauval model computed before. But this model fails to reproduce the surface helium abundance, which is 0.2393 (2.6σ away from the seismic value), and neutrino fluxes. The magnetic model called AGSM keeps the agreement of the AGSR and improves the prediction of the surface helium abundance. The observed separation ratios r02 and r13 are reasonably reproduced by AGSM. Moreover, neutrino fluxes calculated by this model are not far from the detected neutrino fluxes and the predictions of previous works.

  7. Report on carbon and nitrogen abundance studies

    Boehm-Vitense, Erika

    1991-01-01

    The aim of the proposal was to determine the nitrogen to carbon abundance ratios from transition layer lines in stars with different T(sub eff) and luminosities. The equations which give the surface emission line fluxes and the measured ratio of the NV to CIV emission line fluxes are presented and explained. The abundance results are compared with those of photospheric abundance studies for stars in common with the photospheric investigations. The results show that the analyses are at least as accurate as the photospheric determinations. These studies can be extended to F and early G stars for which photospheric abundance determinations for giants are hard to do because molecular bands become too weak. The abundance determination in the context of stellar evolution is addressed. The N/C abundance ratio increases steeply at the point of evolution for which the convection zone reaches deepest. Looking at the evolution of the rotation velocities v sin i, a steep decrease in v sin i is related to the increasing depth of the convection zone. It is concluded that the decrease in v sin i for T(sub eff) less than or approximately = 5800 K is most probably due to the rearrangement of the angular momentum in the stars due to deep convective mixing. It appears that the convection zone is rotating with nearly depth independent angular momentum. Other research results and ongoing projects are discussed.

  8. TEA: A Code Calculating Thermochemical Equilibrium Abundances

    Blecic, Jasmina; Harrington, Joseph; Bowman, M. Oliver

    2016-07-01

    We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. and Eriksson. It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature–pressure pairs. We tested the code against the method of Burrows & Sharp, the free thermochemical equilibrium code Chemical Equilibrium with Applications (CEA), and the example given by Burrows & Sharp. Using their thermodynamic data, TEA reproduces their final abundances, but with higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is available under a reproducible-research, open-source license via https://github.com/dzesmin/TEA.

  9. Modelling Void Abundance in Modified Gravity

    Voivodic, Rodrigo; Llinares, Claudio; Mota, David F

    2016-01-01

    We use a spherical model and an extended excursion set formalism with drifting diffusive barriers to predict the abundance of cosmic voids in the context of general relativity as well as f(R) and symmetron models of modified gravity. We detect spherical voids from a suite of N-body simulations of these gravity theories and compare the measured void abundance to theory predictions. We find that our model correctly describes the abundance of both dark matter and galaxy voids, providing a better fit than previous proposals in the literature based on static barriers. We use the simulation abundance results to fit for the abundance model free parameters as a function of modified gravity parameters, and show that counts of dark matter voids can provide interesting constraints on modified gravity. For galaxy voids, more closely related to optical observations, we find that constraining modified gravity from void abundance alone may be significantly more challenging. In the context of current and upcoming galaxy surv...

  10. Liquid and gas chromatography coupled to isotope ratio mass spectrometry for the determination of 13C-valine isotopic ratios in complex biological samples.

    Godin, Jean-Philippe; Breuillé, Denis; Obled, Christiane; Papet, Isabelle; Schierbeek, Henk; Hopfgartner, Gérard; Fay, Laurent-Bernard

    2008-10-01

    On-line gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is commonly used to measure isotopic ratios at natural abundance as well as for tracer studies in nutritional and medical research. However, high-precision (13)C isotopic enrichment can also be measured by liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Indeed, LC-IRMS can be used, as shown by the new method reported here, to obtain a baseline separation and to measure (13)C isotopic enrichment of underivatised amino acids (Asp, Thr-Ser, Glu, Pro, Gly, Ala, Cys and Val). In case of Val, at natural abundance, the SD(delta(13)C) reported with this method was found to be below 1 per thousand . Another key feature of the new LC-IRMS method reported in this paper is the comparison of the LC-IRMS approach with the conventional GC-C-IRMS determination. To perform this comparative study, isotopic enrichments were measured from underivatised Val and its N(O, S)-ethoxycarbonyl ethyl ester derivative. Between 0.0 and 1.0 molar percent excess (MPE) (delta(13)C= -12.3 to 150.8 per thousand), the calculated root-mean-square (rms) of SD was 0.38 and 0.46 per thousand and the calculated rms of accuracy was 0.023 and 0.005 MPE, respectively, for GC-C-IRMS and LC-IRMS. Both systems measured accurately low isotopic enrichments (0.002 atom percent excess (APE)) with an SD (APE) of 0.0004. To correlate the relative (delta(13)C) and absolute (atom%, APE and MPE) isotopic enrichment of Val measured by the GC-C-IRMS and LC-IRMS devices, mathematical equations showing the slope and intercept of the curves were established and validated with experimental data between 0.0 to 2.3 MPE. Finally, both GC-C-IRMS and LC-IRMS instruments were also used to assess isotopic enrichment of protein-bound (13)C-Val in tibial epiphysis in a tracer study performed in rats. Isotopic enrichments measured by LC-IRMS and GC-C-IRMS were not statistically different (p>0.05). The results of this work indicate that

  11. Isotopes in the interstellar medium and circumstellar envelopes

    Measurements of the present-day abundances of elements and isotopes, combined with model calculations, allow us to trace the history of nucleosynthesis in the universe. Throughout this review, emphasis will be placed on descriptions of the measurement processes and the interpretations needed to obtain actual isotope and element abundances from measurements. Comparisons of the abundances of isotopomers of a given element are less affected by systematic effects than are comparisons of the abundances of different elements. Thus ratios of isotopomers should be given a greater weight when data and models are compared. As is generally accepted, the universe began with an explosive event, the Big Bang. The nucleosynthesis associated with this event produced 'primordial' abundances of the 'light elements', deuterium, 3He, 4He, and 7Li. Subsequent stellar processing of the light elements has altered the relative abundances, and also produced heavier elements such as carbon, nitrogen and oxygen. Stellar nucleosynthesis products from solar and larger mass stars are expelled into the interstellar medium (ISM). The goal of studies of the abundances of the light elements is to estimate the primordial abundances, that is, the abundances produced in the Big Bang. It is believed that D is always net destroyed in stars; 3He and 7Li may be net produced, 4He is certainly net produced. In the Solar System itself, results are obtained from in situ measurements with space probes to Jupiter, measurements of solar wind constituents, the analysis of the content of meteorites, and spectral line measurements of the solar photosphere. For sources outside the Solar System, these data are based on spectral line measurements of gas-phase species. The ratio of gas-phase abundances of elements, such as carbon to lithium may be affected by differing amounts of condensation onto dust grains; however such a process will not affect the ratio of isotopes such as 6Li/7Li. The most reliable measurements

  12. Extreme lithium isotopic fractionation in three zircon standards (Plešovice, Qinghu and Temora)

    Yu-Ya Gao; Xian-Hua Li; Griffin, William L.; Yan-Jie Tang; Norman J. Pearson; Yu Liu; Mei-Fei Chu; Qiu-Li Li; Guo-Qiang Tang; O’Reilly, Suzanne Y.

    2015-01-01

    To understand the behavior of Li in zircon, we have analyzed the abundance and isotopic composition of Li in three zircon standards (Plešovice, Qinghu and Temora) widely used for microbeam analysis of U-Pb ages and O-Hf isotopes. We have mapped Li concentration ([Li]) on large grains, using a Cameca 1280HR Secondary Ion Mass Spectrometer (SIMS). All zircons have a rim 5–20 μm wide in which [Li] is 5 to 20 times higher than in the core. Up to ~20‰ isotopic fractionation is observed on a small ...

  13. Direct U isotope analysis in μm-sized particles by LA-MC-ICPMS

    Full text: The knowledge of the isotopic composition of individual μm-sized hot particles is of great interest especially for strengthened nuclear safeguards in order to identify undeclared nuclear activities. We present the potential of a 'Nu Plasma HR' MC-ICPMS coupled to a New Wave 'UP 193' laser ablation (LA) system for the direct analysis of U isotope abundance ratios in individual μm-sized particles. The ability to determine 234U/238U and 235U/238U isotope ratios was successfully demonstrated in the NUSIMEP-6 interlaboratory comparison, which was organized by the IRMM (Geel, Belgium). (author)

  14. Migration dynamics of clupeoids in the Schelde estuary: a stable isotope approach

    Guelinckx, J.; Maes, J.; De Brabandere, Loreto;

    2006-01-01

    movement in the Schelde estuary. Seasonal movements of clupeoids in the Schelde estuary were analyzed by separating the temporal abundance patterns into migration groups based on their muscle isotopic composition. Immigration and emigration seem to occur continuously throughout the year. Most exchange...... occurred in November. During winter, immigration remained high but gradually decreased. Although the herring and sprat abundance further declined in the estuary during February and March, large seaward emigration was not fully demonstrated. As temporal overlap between immigration and emigration is...

  15. High-precision measurements of heavy p-process isotopes in early solar system materials

    Peters, Stefan Theodorus Maria

    2014-01-01

    This work investigates the abundances of rare, neutron poor isotopes of some heavy elements in meteorites. The elements in the solar system that are heavier than H and He were predominantly produced in stars. The Sun cannot have produced these elements during its lifetime as a small main sequence star, and their abundances must therefore have been inherited from interstellar matter that was produced by pre-existing massive stars. The elements lighter than iron were produced by nuclear fusion,...

  16. Discoveries of isotopes by fission

    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.

  17. Isotope hydrology experiments

    From the concentrations of H2 and O18 in the examined ground waters in the Lower Muschelkalk of the SW flank of the Asse mine it can be inferred that the flow field of the ground water with the isotopic composition of the recent precipitations has an effect down to a depth of only 611 to 744 m. (DG)

  18. GEOCHRONOMETRY & ISOTOPE GEOLOGY

    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.)

  19. Isotopes in aquaculture research

    The applications of isotopes in aquaculture research include areas like aquatic production process, nutrient cycles and food chain dynamics, fish nutrition, fish physiology, genetics and immunology. The radioisotopes commonly used are beta emitters. The use of different radioisotopes in aquaculture research are presented. 2 tabs

  20. Forensic Stable Isotope Biogeochemistry

    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.

  1. Isotopic geochemistry of calcretes

    Sr, C, O, U and Th isotopes have been studied in calcium carbonates accumulated in soils of semi-arid regions (calcretes). We have investigated 1) the role of in-situ weathering and climatic conditions in the genesis of calcretes from Central Spain (Toledo) and Atlantic Morocco (Sidi Ifni), 2) the origin of Ca, and 3) the age of these accumulations. Our results show that calcium carbonates replace the parent rock (granite) and preserve the bulk-volume. Sr isotopic data suggest that 90 % of Ca in the spanish calcretes is allochthonous and related to atmospheric input. O and C isotopic compositions of the carbonates are compatible with soil temperatures and respiration rates during the beginning of the summer season. U-series disequilibrium in the carbonates suggests ages ranging between 40 to 270 ky, commensurate with the climatic cycle. The Sr isotopic signatures of spanish and moroccan calcretes are similar to those of the Quaternary marine carbonates. Assuming that only Ca-rich aerosols have been the source for calcretes of the studied regions, we propose that the wide continental plateaus exposed during glacial periods (low sea level) provided a major part of the calcic input to the soils. Semi-arid conditions of Spain and Morocco allowed the percolation and precipitation in the soil profiles to form calcretes. (author)

  2. Natural abundance of /sup 15/N in soil organic matter with special reference to paddy soils in Japan. Biogeochemical implications on the nitrogen cycle

    Wada, Eitaro; Imaizumi, Reiko (Mitsubishi Chemical Industries Ltd., Tokyo (Japan)); Takai, Yasuo

    1984-01-01

    In order to explain the general principle which controls the /sup 15/N content of soil organic nitrogen, experimental rice fields which were fertilized for long term were investigated. The /sup 15/N abundance values of rice plants vary according to the kinds of fertilizer, e.g., chemical fertilizer and green manure. The significant difference of /sup 15/N abundance was recognized between rice plants and fertilizers. Nitrification and denitrification seemed to be responsible for the difference. But these have minor effect on the variation of /sup 15/N abundance of soil because rice plants assimilate all available nitrogen and are removed from paddy fields by harvest. Consequently, the effects of nitrification-denitrification and ammonia volatilization are observed only in biological process such as the growth of rice plants and hydrophytes. A long term addition of fertilizers clearly increased the amount of soil organic nitrogen in paddy fields. Based on isotope mass balance, nitrogen isotope fractionation factor of 0.9942 was estimated in the process of epidiagenesis which indicates the selective decomposition of heavy isotopic species. An addition of ammonium sulfate with low /sup 15/N abundance decreased the /sup 15/N content of soil nitrogen in the paddy fields with the depletion of soil organic nitrogen. OrgC/clay ratio was demonstrated as an important factor which controls the /sup 15/N abundance value in paddy soil. The relation between the /sup 15/N abundance value in soil organic nitrogen and OrgC/clay ratio was able to be presented by hyperbola for the paddy soild so far examined. The /sup 15/N abundance of source and plant nitrogen two isotopic fractionation associated with the epidiagenesis of soil organic matter and the adsorption of ammonia by clay minerals are the three major factors determining the /sup 15/N abundance of soil organic nitrogen.

  3. DANCEing with the Stars: Measuring Neutron Capture on Unstable Isotopes with DANCE

    Isotopes heavier than iron are known to be produced in stars through neutron capture processes. Two major processes, the slow (s) and rapid (r) processes are each responsible for 50% of the abundances of the heavy isotopes. The neutron capture cross sections of the isotopes on the s process path reveal information about the expected abundances of the elements as well as stellar conditions and dynamics. Until recently, measurements on unstable isotopes, which are most important for determining stellar temperatures and reaction flow, have not been experimentally feasible. The Detector for Advance Neutron Capture Experiments (DANCE) located at the Los Alamos Neutron Science Center (LANSCE) was designed to perform time-of-flight neutron capture measurements on unstable isotopes for nuclear astrophysics, stockpile stewardship, and reactor development. DANCE is a 4-πBaF2 scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

  4. Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

    Brand, Willi A.; Coplen, Tyler B.; Vogl, Jochen; Rosner, Martin; Prohaska, Thomas

    2014-01-01

    Since the early 1950s, the number of international measurement standards for anchoring stable isotope delta scales has mushroomed from 3 to more than 30, expanding to more than 25 chemical elements. With the development of new instrumentation, along with new and improved measurement procedures for studying naturally occurring isotopic abundance variations in natural and technical samples, the number of internationally distributed, secondary isotopic reference materials with a specified delta value has blossomed in the last six decades to more than 150 materials. More than half of these isotopic reference materials were produced for isotope-delta measurements of seven elements: H, Li, B, C, N, O, and S. The number of isotopic reference materials for other, heavier elements has grown considerably over the last decade. Nevertheless, even primary international measurement standards for isotope-delta measurements are still needed for some elements, including Mg, Fe, Te, Sb, Mo, and Ge. It is recommended that authors publish the delta values of internationally distributed, secondary isotopic reference materials that were used for anchoring their measurement results to the respective primary stable isotope scale.

  5. Modelling of mercury isotope separation in CP stellar atmospheres: results and problems

    Sapar, A; Sapar, L; Poolamäe, R; 10.1016/j.newar.2009.08.010

    2009-01-01

    Formation of anomalous isotope abundances in the atmospheres of chemically peculiar (CP) stars can be explained by light-induced drift (LID). This effect is additional to the radiative acceleration and appears due to systematic asymmetry of radiative flux in partly overlapping isotopic spectral line profiles. LID causes levitation of an isotope with a red-shifted spectral line and sinking of an isotope with a blue-shifted line, generating thus diffusive separation of isotopes. We have studied diffusion of mercury as a typical well-studied isotope-rich heavy metal. Our model computations show that in mercury-rich quiescent atmospheres of CP stars LID causes levitation of the heavier mercury isotopes and sinking of the lighter ones. Precise quantitative modelling of the process of isotope separation demands very high-resolution computations and the high-precision input data, including data on hyperfine and isotopic splitting of spectral lines, adequate line profiles and impact cross-sections. Presence of microt...

  6. Models for Water Isotopes Constrained with Data from Crystal Face

    Toon, Owen B.

    2005-01-01

    During the year covered by this proposal we conducted work on several different topics, as reflected by our publications listed below. One major activity was to work with a group of about 10 scientists from around the country to prepare a science-planning document (Tropical Composition, Cloud and Climate Coupling Experiment (TC4)) that outlined the rationale, locations, strategy to accomplish the goals, and possible payloads for a set of three tropical missions. We also prepared background materials for various NRAs being prepared at NASA Headquarters for missions in Costa Rica, Darwin and Guam. Unfortunately budgetary constraints prevented these missions from moving forward. In conjunction with the group NASA Ames we built a new numerical model for deep convection and have applied that model to simulate the CRYSTAL isotope data. Our goal in particular has been to better understanding how convection distributes water vapor isotopes. CRYSTAL observations of water isotopes are very different from those suggested by previous workers who assumed the isotopes would obey Rayleigh fractionation. The water isotope study has several implications. First it is a check on the realism of the deep convection model. Second, the isotopes are a measure of the precipitation removal in the atmosphere. Hence they provide a constraint on a parameter that is difficult to otherwise measure. Finally it has been suggested that isotopes may be the key to unraveling the water transport into the stratosphere and upper troposphere. Such transport is critical both for the radiation balance and for stratospheric chemistry. Ours is the first model that is able to treat this transport. Our initial results are now in press in Geophys. Res. Lett. Essentially we are able to explain the vertical profiles of isotopes in the tropical tropopause transition layer. We are also able to account for stratospheric humidity ana isotope abundances with this model. The data suggest that isotopes do not provide a

  7. Clonal growth and plant species abundance

    Herben, Tomáš; Nováková, Zuzana; Klimešová, Jitka

    2014-01-01

    Background and Aims Both regional and local plant abundances are driven by species' dispersal capacities and their abilities to exploit new habitats and persist there. These processes are affected by clonal growth, which is difficult to evaluate and compare across large numbers of species. This study assessed the influence of clonal reproduction on local and regional abundances of a large set of species and compared the predictive power of morphologically defined traits of clonal growth with data on actual clonal growth from a botanical garden. The role of clonal growth was compared with the effects of seed reproduction, habitat requirements and growth, proxied both by LHS (leaf–height–seed) traits and by actual performance in the botanical garden. Methods Morphological parameters of clonal growth, actual clonal reproduction in the garden and LHS traits (leaf-specific area – height – seed mass) were used as predictors of species abundance, both regional (number of species records in the Czech Republic) and local (mean species cover in vegetation records) for 836 perennial herbaceous species. Species differences in habitat requirements were accounted for by classifying the dataset by habitat type and also by using Ellenberg indicator values as covariates. Key Results After habitat differences were accounted for, clonal growth parameters explained an important part of variation in species abundance, both at regional and at local levels. At both levels, both greater vegetative growth in cultivation and greater lateral expansion trait values were correlated with higher abundance. Seed reproduction had weaker effects, being positive at the regional level and negative at the local level. Conclusions Morphologically defined traits are predictive of species abundance, and it is concluded that simultaneous investigation of several such traits can help develop hypotheses on specific processes (e.g. avoidance of self-competition, support of offspring) potentially

  8. Obtaining and separation of isotopically pure {sup 88}Y as component of calibration multisources; Otrzymywanie czystego nuklidowo itru {sup 88}Y jako skladnika wieloizotopowych zrodel kalibracyjnych

    Misiak, R.; Ochab, E. [The H. Niewodniczanski Inst. of Nuclear Physics, Cracow (Poland)

    1997-12-01

    Strontium chloride of natural isotopic abundance was bombarded with 13 MeV deuterons and then processed chemically. The thick target yields of {sup 88}Y and other yttrium isotopes were determined. The yield of chemical preparation was found to be 91,2%. Optimum conditions for obtaining and separation of {sup 88}Y were discussed. (author) 3 refs, 5 figs

  9. Linking species abundance distributions in numerical abundance and biomass through simple assumptions about community structure

    Henderson, Peter A.; Magurran, Anne E

    2010-01-01

    Species abundance distributions (SADs) are widely used as a tool for summarizing ecological communities but may have different shapes, depending on the currency used to measure species importance. We develop a simple plotting method that links SADs in the alternative currencies of numerical abundance and biomass and is underpinned by testable predictions about how organisms occupy physical space. When log numerical abundance is plotted against log biomass, the species lie within an approximat...

  10. Zinc isotopic evidence for the origin of the Moon.

    Paniello, Randal C; Day, James M D; Moynier, Frédéric

    2012-10-18

    Volatile elements have a fundamental role in the evolution of planets. But how budgets of volatiles were set in planets, and the nature and extent of volatile-depletion of planetary bodies during the earliest stages of Solar System formation remain poorly understood. The Moon is considered to be volatile-depleted and so it has been predicted that volatile loss should have fractionated stable isotopes of moderately volatile elements. One such element, zinc, exhibits strong isotopic fractionation during volatilization in planetary rocks, but is hardly fractionated during terrestrial igneous processes, making it a powerful tracer of the volatile histories of planets. Here we present high-precision zinc isotopic and abundance data which show that lunar magmatic rocks are enriched in the heavy isotopes of zinc and have lower zinc concentrations than terrestrial or Martian igneous rocks. Conversely, Earth and Mars have broadly chondritic zinc isotopic compositions. We show that these variations represent large-scale evaporation of zinc, most probably in the aftermath of the Moon-forming event, rather than small-scale evaporation processes during volcanism. Our results therefore represent evidence for volatile depletion of the Moon through evaporation, and are consistent with a giant impact origin for the Earth and Moon. PMID:23075987

  11. Isotopically engineered Si and Ge for spintronics and quantum computation

    Si, Ge as well as SiGe structures are the promising materials for spintronics and quantum computation due to the fact that in both crystals only one isotope (29Si and 73Ge) has nuclear spin. As a result, isotope engineering of Si and Ge permits to control the density of nuclear spins and vary the spin coherence time, a crucial parameter in spintronics. In the first part we discuss the NMR study of nuclear spin decoherence in Ge single crystals with different abundance of the 73Ge isotope. It was observed that the slow component of the dephasing process is elongated with depletion of Ge crystal with isotope 73Ge. The second part is devoted to the development of the Kane's model of nuclear spin-based quantum computer, which uses the nuclear spin of 31P impurity atoms in a 28Si matrix as quantum bits (qubits). We discuss a new method of placing 31P atoms in a 28Si based on neutron-transmutation-doping of isotopically engineered Si and Ge. In the proposed structure, interqubit coupling is due to indirect hyperfine interaction of 31P nuclear spins with electrons localized in a 28Si quasi-one-dimensional nanowire, which allows one to control the coupling between distant qubits

  12. Isotope techniques in the study of environmental change

    The International Atomic Energy Agency, among its efforts to promote the wider use of isotope techniques in hydrology and related environmental disciplines, organized an International Symposium on Applications of Isotope Techniques in Studying Past and Current Environmental Changes in the Hydrosphere and the Atmosphere, held in 1993 in Vienna. The broad scientific interest and abundant participation in the symposium, as well as the rapid progress seen in this field since then, encouraged the IAEA to organize a second symposium of this kind. It was held from 14 to 18 April 1997 in Vienna and brought together 177 scientists representing 46 Member States, UNESCO, FAO, WMO, the World Climate Research Programme (WCRP) and the International Geosphere-Biosphere Programme (IGBP). The symposium was structured in five sessions of oral presentations, a poster session and a round table discussion that focused on trends and future requirements in isotope hydrology and on applications in climate and environmental research. The major themes covered by the presentations included the use of isotopic tracers in studies of atmospheric and hydrospheric changes and of the human impact on water and the environment. Special emphasis was placed on isotopic archives of climatic and environmental change. Some contributions addressed new technical approaches

  13. Nitrogen 15 abundance in protein fractions of beans fertilized with ({sup 15}NH{sub 4}){sub 2}SO{sub 4}

    Chaud, Saula Goulart; Oliveira, Admar Costa de [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Estudos Agricolas. Dept. de Planejamento Alimentar e Nutricao; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis]. E-mail: admarco@fea.unicamp.br

    2002-12-01

    Studies evaluating the protein nutritive value of beans labelled with 15 N, using nitrogen balance and the quantitation of faecal and urinary endogenous nitrogen, determined by isotopic dilution, have been extensively used. The objective of this research was to verify if the isotopic labelling of raw, freeze dried beans (Phaseolus vulgaris L., cultivar Pirata 1) with 1.394 atoms % 15 N, resulted in the same abundance of the whole flour and of the protein fractions extracted from the beans with 0.5 mol L{sup -1} NaCl. The isotopic abundance found in the whole bean flour, in the protein extract, in the globulin and albumin fractions were respectively: 1.394 +- 0.011; 1.403 +- 0.012; 1.399 +- 0.007 and 1.399 +- 0.028 atoms % of 15 N, presenting no difference (P > 0.05). However, a difference was found (P < 0.05) between the above mentioned abundances and the isotopic abundance found in the nitrogen of the proteins in the extraction residue, which was 0.969 +- 0.084. Since the abundances did not differ, the protein nutritive indexes, such as digestibility and biological value, determined from the nitrogen balance and corrected for isotopic dilution, would not be affected by extracting the proteins from the beans with 0.5 mol L 1 NaCl. If working with the nitrogen balance of the residual proteins after extraction and even with the whole flours, these indexes could present incorrect values, since the isotopic labelling of the residual proteins was less than that of the protein fractions. (author)

  14. Mercury stable isotope biogeochemistry

    Full text: Methods for high precision measurement of natural Hg isotope ratios by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) have been developed recently by our group and allow the use of Hg isotopes to trace the biogeochemistry of Hg. Mercury has seven stable isotopes ranging from 196 to 204 amu.We have found that the isotopic composition of Hg varies by both mass dependent fractionation (MDF) and mass independent fractionation (MIF). Even and odd isotopes of Hg are fractionated by mass-dependent processes, whereas odd isotopes are also fractionated in a mass-independent way by photochemical reactions. Isotope ratios are measured relative to the NIST 3133 Hg standard reference material. MDF is reported as δ202Hg (± 0.08 %o, 2 SD) which is the difference in 202Hg/198Hg between a sample and NIST 3133 in permil (%o). MIF is reported as Δ 201Hg (± 0.05 %o, 2 SD), which is the difference in 201Hg/198Hg ratio in permil from what the 201Hg/198Hg ratio would be if the fractionation were entirely mass dependent. In this presentation we summarize the range of Hg isotopic compositions of a variety of environmental and geological materials. In previous work we described biotic and abiotic laboratory fractionation experiments demonstrating the range of mass dependent and mass independent fractionation caused by mercury redox transformations in the surface environment. Thus far we have found that MIF occurs during photochemical reduction of methyl-Hg and Hg2+ following a Rayleigh-like fractionation. Bacterial reduction causes Rayleigh-like MDF but no MIF. Coastal-marine and freshwater fish from North America have positive Δ 201Hg values (0.2 to > 3 %o) reflecting transfer of methyl-Hg into the food web after partial reduction by photochemical reactions. Most coals and the organic horizons of soils from North America have negative Δ 201Hg values (-0.1 to -0.4 %o), possibly reflecting the influence of Hg that was photochemically reduced in

  15. Radio observations of carbon monoxide toward Zeta Ophiuchi - Velocity structure, isotopic abundances, and physical properties

    Langer, William D.; Glassgold, Alfred E.; Wilson, Robert W.

    1987-01-01

    This paper presents a small-scale map of the molecular gas around the line of sight toward Zeta Oph made with measurements of the (C-12)O (1-0) emission obtained at high signal-to-noise ratio and high velocity resolution. In addition, a measurement of the (C-12)O (2-1) line emission and a detection of (C-13)O along the line of sight to the star are reported. The results show that the CO emission toward the star is composed from at least four components with peak velocities at -2.0, -0.7, 0.0, and +0.6 km/s. The radio observations yield a total CO column density of 1.4 x 10 to the 15th/sq cm, with about one-half of the total CO column density being in the main component at -0.7 km/s. The main cmponent is uniform over the map, but the other components are variable, suggesting that the cloud is clumpy. The data on the two CO transitions imply that the excitation temperature and the density of the main component are about 7 K and 800/cu cm, respectively.

  16. An instrument for elemental and isotopic abundance characterization of extra-terrestrial materials

    Veryovkin, I. V.; Calaway, W. F.; Moore, J. F.; Pellin, M. J.; Savina, M. R.; King, B. V.; Petravić, M.; Burnett, D. S.

    2002-12-01

    Samples returned from the Genesis and Stardust missions of NASA's Discovery Program require quantitative analysis at sensitivities unobtainable with present instruments. This has driven development of a new generation of instruments for laser-post-ionization secondary neutral mass spectrometry (laser-SNMS). Construction of a prototype time-of-flight (TOF) SNMS instrument has been completed recently at Argonne National Laboratory (ANL) and testing began in August 2002. This instrument is optimized for laser post-ionization of sputtered neutrals and is capable of locating and analyzing individual sub-micrometer interstellar particles on a sample stage for Stardust or determining elemental concentrations in shallow implants at ultra-trace levels for Genesis. Post-ionization can be accomplished with a variety of laser sources. These include high repetition rate tunable Ti-sapphire lasers for ultra-trace analysis of a single element and two vacuum ultraviolet (VUV) light sources for simultaneous ionization of most atomic and molecular species in the sample. The two VUV lasers are an F2 laser with a fixed wavelength of 157 nm and the self-amplified spontaneous emission free-electron laser (SASE FEL) capable of generating tunable VUV at wavelengths down to 60 nm. Fundamental physical theory of ion sputtering forms the scientific basis of the approach used to design the instrument. An ion optics design for the instrument was perfected through extensive three-dimensional computer simulations using SIMION software. Realistic sets of photo-ions were calculated using formalisms derived from sputtering theory. Their trajectories in various instrument designs were then traced by SIMION. Finally, results of the simulations were processed to estimate instrument capabilities including resolution and useful yield. This same approach proved accurate and quantitative during tests of an existing TOF SNMS instrument demonstrating the reliability of the simulation method. The completed prototype instrument and results of recent tests will be presented. This work is supported by the U. S. Department of Energy, BES-Materials Sciences, under Contract W-31-109-ENG-38 and in part by a contract from NASA's Office of Space Science's Cosmochemistry Program.

  17. Peptides and proteins in a confined environment: NMR spectra at natural isotopic abundance.

    Pastore, Annalisa; Salvadori, Severo; Temussi, Piero Andrea

    2007-05-01

    Confinement of proteins and peptides in a small inert space mimics the natural environment of the cell, allowing structural studies in conditions that stabilize folded conformations. We have previously shown that confinement in polyacrylamide gels (PAGs) is sufficient to induce a change in the viscosity of the aqueous solution without changing the composition and temperature of the solvent. The main limitation of a PAG to run NMR experiments in a confined environment is the need for labelling the peptides. Here we report the use of the agarose gel to run the NMR spectra of proteins and peptides. We show that agarose gels are completely transparent in NMR experiments, relieving the need for labelling. Although it is necessary to expose biomolecules to fairly high temperatures during sample preparation, we believe that this is not generally an obstacle to the study of peptides, and found that the method is also compatible with temperature-resistant proteins. The mesh of agarose gels is too wide for direct effects of confinement on the stability of proteins but confinement can be easily exploited to interact the proteins with other reagents, including crowding macromolecules that can eventually lead to fold stabilization. The use of these gels is ideally suited for low-temperature studies; we show that a very flexible peptide at subzero temperatures is stabilized into a well-folded conformation. PMID:17436341

  18. Silicon isotopic abundance toward evolved stars and its application for presolar grains

    Peng, T -C; Testi, L; Baudry, A; Wittkowski, M; Rawlings, M G; de Gregorio-Monsalvo, I; Vlemmings, W; Nyman, L -A; Gray, M D; de Breuck, C

    2013-01-01

    Galactic chemical evolution (GCE) is important for understanding the composition of the present-day interstellar medium (ISM) and of our solar system. In this paper, we aim to track the GCE by using the 29Si/30Si ratios in evolved stars and tentatively relate this to presolar grain composition. We used the APEX telescope to detect thermal SiO isotopologue emission toward four oxygen-rich M-type stars. Together with the data retrieved from the Herschel science archive and from the literature, we were able to obtain the 29Si/30Si ratios for a total of 15 evolved stars inferred from their optically thin 29SiO and 30SiO emission. These stars cover a range of masses and ages, and because they do not significantly alter 29Si/30Si during their lifetimes, they provide excellent probes of the ISM metallicity (or 29Si/30Si ratio) as a function of time. The 29Si/30Si ratios inferred from the thermal SiO emission tend to be lower toward low-mass oxygen-rich stars (e.g., down to about unity for W Hya), and close to an int...

  19. Relationship between the natural abundance of soil nitrogen isotopes and condition in North Dakota wetlands

    A statewide condition assessment of North Dakota wetlands in the summer of 2011 was conducted as part of the U.S. Environmental Protection Agency’s National Wetland Condition Assessment (NWCA). Two other wetland condition assessments, the Index of Plant Community Integrity (IPCI...

  20. Separating soil respiration components with stable isotopes: natural abundance and labelling approaches

    Braig E; Tupek B

    2010-01-01

    Due to the potential of forest ecosystems contributing to CO2 increase as well as to climate change mitigation, forest-atmosphere CO2 exchange has been intensively studied over last decades. However, the contribution of individual components of belowground carbon pools is still poorly known. In particular, there is no unequivocal means to separate root respiration (autotrophic) from heterotrophic respiration by soil microflora and fauna. Most studies investigating soil respiration disturbed t...

  1. Good abundances from bad spectra; 1, techniques

    Bryn, J; Wyse, R F G; Gilmore, Gerard; Wyse, Rosemary F G

    1995-01-01

    We have developed techniques to extract true iron abundances and surface gravities from spectra of the type provided by the multiple-object fibre-fed spectroscopic radial-velocity surveys underway with 2dF, HYDRA, NESSIE, and the forthcoming Sloan survey. Our method is optimised for low S/N, intermediate resolution blue spectra of G stars. Spectroscopic indices sensitive to iron abundance and gravity are defined from a set of narrow (few Angstrom) wavelength intervals, and calibrated using synthetic spectra. We have also defined a single abundance indicator which is able to provide useful iron abundance information from spectra having S/N ratios as low as 10 per Angstrom. The theoretical basis and calibration using synthetic spectra are described in this paper. The empirical calibration of these techniques by application to observational data is described in Jones, Wyse and Gilmore (PASP July 1995). The technique provides precise iron abundances, with zero-point correct to \\sim 0.1 dex, and is reliable, with ...

  2. Oxygen abundance maps of CALIFA galaxies

    Zinchenko, I A; Grebel, E K; Sanchez, S F; Vilchez, J M

    2016-01-01

    We construct maps of the oxygen abundance distribution across the disks of 88 galaxies using CALIFA data release 2 (DR2) spectra. The position of the center of a galaxy (coordinates on the plate) were also taken from the CALIFA DR2. The galaxy inclination, the position angle of the major axis, and the optical radius were determined from the analysis of the surface brightnesses in the SDSS $g$ and $r$ bands of the photometric maps of SDSS data release 9. We explore the global azimuthal abundance asymmetry in the disks of the CALIFA galaxies and the presence of a break in the radial oxygen abundance distribution. We found that there is no significant global azimuthal asymmetry for our sample of galaxies, i.e., the asymmetry is small, usually lower than 0.05 dex. The scatter in oxygen abundances around the abundance gradient has a comparable value, $\\lesssim 0.05$ dex. A significant (possibly dominant) fraction of the asymmetry can be attributed to the uncertainties in the geometrical parameters of these galaxie...

  3. Abundances of Molecular Species in Barnard 68

    Francesco, J D; Welch, W J; Bergin, E A; Francesco, James Di; Hogerheijde, Michiel R.; Welch, William J.; Bergin, Edwin A.

    2002-01-01

    Abundances for 5 molecules (C18O, CS, NH3, H2CO, and C3H2) and 1 molecular ion (N2H+) and upper limits for the abundances of 1 molecule (13CO) and 1 molecular ion (HCO+) are derived for gas within the Bok globule Barnard 68 (B68). The abundances were determined using our own BIMA millimeter interferometer data and single-dish data gathered from the literature, in conjunction with a Monte Carlo radiative transfer model. Since B68 is the only starless core to have its density structure strongly constrained via extinction mapping, a major uncertainty has been removed from these determinations. All abundances for B68 are lower than those derived for translucent and cold dense clouds, but perhaps only significantly for N2H+, NH3, and C3H2. Depletion of CS toward the extinction peak of B68 is hinted at by the large offset between the extinction peak and the position of maximum CS line brightness. Abundances derived here for C18O and N2H+ are consistent with other, recently determined values at positions observed in...

  4. Ensuring reliable medical isotope supply

    This paper describes the role of MDS Nordion and AECL in ensuring a reliable global supply of medical isotopes. The First part of the paper discusses the uses of medical isotopes, their importance to the medical community, and the benefits to patients of a secure supply of medical isotopes. The second part describes the role of the NRU reactor and the future role of the MAPLE reactors and New Processing Facility being commissioned at AECL's Chalk River Laboratories for production of medical isotopes to meet the world market demand for the next 40 years. MDS Nordion is the world's leading supplier of medical isotopes. These isotopes are used to conduct some 34,000 nuclear medicine procedures performed every day around the world, such as determining the severity of heart disease, the spread of cancer, and diagnosing brain disorders. These medical isotopes are currently produced primarily by AECL in the NRU reactor at Chalk River, Ontario, Canada. (author)

  5. Chromium isotope uptake in carbonates

    Rodler, Alexandra

    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....... Processes that potentially fractionate Cr isotopes, perhaps during deposition, burial and alteration need to be constrained.Previous studies have shown that Cr isotopes are fractionated during oxidative weathering on land, where heavy Cr isotopes are preferentially removed with Cr(VI) while residual soils...... retain an isotopically light Cr signature. Cr(VI) enriched in heavy Cr isotopes is then transported via river waters to the oceans and sequestered into marine sediments. Marine chemical sediments such asbanded iron formations and modern marine carbonates have proven useful in recording the Cr isotope...

  6. Isotope geochemistry of the Amazon Basin: A reconnaissance

    Longinelli, A.; Edmond, J. M.

    1983-04-01

    On the transects of the Amazon River made by the Alpha Helix in 1976 and 1977, an extensive suite of samples was collected for isotopic analyses. The water isotopes (18O/16O, D/H) were determined in atmospheric water vapour and in river, rain, and leaf waters. 13C/12C ratios were measured in the dissolved and atmospheric CO2. Determinations were made of 34S/32S and oxygen isotopes in dissolved sulphate. The effect of `continentality' on the water isotopes is minor reflecting the large scale recycling by evapotranspiration from the huge area of forest within the basin. Variations in the isotopic abundances between 1976 (June-July, dry season) and 1977 (May-June, end of wet season) are consistent with the changes in meteorological conditions. The isotopic composition of the CO2, both atmospheric and dissolved, is dominated by biological effects. In 1976 the dissolved CO2 showed downstream variations from -14‰ at Iquitos in Peru to -22‰ in the lower reaches. In 1977, no systematic trend was apparent, the data ranging around -19‰. The values for atmospheric CO2 decrease inland from marine values at the mouth to around -15‰ at Manaus. During the dry season (1976) the values in the interior, western basin were homogeneous at -20‰. In the wet season there were considerable variations reflecting atmospheric instabilities with the average value being about -13‰. The sulphur isotopic composition of the dissolved sulphate is remarkably uniform at around 7‰. In 1977 the 18O values in the sulphate decreased systematically downstream from 8‰ in Peru to 3‰ at the mouth, consistent with a progressive, redox-mediated exchange with water and dissolved oxygen. In 1977 the values increased to over 11‰, apparently indicating exchange with a highly fractionated reservoir of dissolved oxygen perhaps in the semireducing environment of the flood plain lakes.

  7. Production of stable isotopes utilizing the plasma separation process

    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 TheragenicsTM 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. TheragenicsTM 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, TheragenicsTM has utilized the PSP to separate isotopes of several elements including: dysprosium, erbium, gadolinium, molybdenum and nickel. Currently, TheragenicsTM 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

  8. Isotope geochemistry of the Amazon Basin: A reconnaissance

    On the transects of the Amazon River made by the Alpha Helix in 1976 and 1977, an extensive suite of samples was collected for isotopic analyses. The water isotopes (18O/16O, D/H) were determined in atmospheric water vapour and in river, rain, and leaf waters. 13C/12C ratios were measured in the dissolved and atmospheric CO2. Determinations were made of 34S/32S and oxygen isotopes in dissolved sulphate. The effect of 'continentality' on the water isotopes is minor reflecting the large scale recycling by evapotranspiration from the huge area of forest within the basin. Variations in the isotopic abundances between 1976 (June--July, dry season) and 1977 (May--June, end of wet season) are consistent with the changes in meteorological conditions. The isotopic composition of the CO2, both atmospheric and dissolved, is dominated by biological effects. In 1976 the dissolved CO2 showed downstream variations from -14X at Iquitos in Peru to -22X in the lower reaches. In 1977, no systematic trend was apparent, the data ranging around -19X. The values for atmospheric CO2 decrease inland from marine values at the mouth to around -15X at Manaus. During the dry season (1976) the values in the interior, western basin were homogeneous at -20X. In the wet season there were considerable variations reflecting atmospheric instabilities with the average value being about -13X. The sulphur isotopic composition of the dissolved sulphate is remarkably uniform at around 7X. In 1977 the 18O values in the sulphate decreased systematically downstream from 8X in Peru to 3X at the mouth, consistent with a progressive redox-mediated exchange with water and dissolved oxygen. In 1977 the values increased to over 11X, apparently indicating exchange with a highly fractionated reservoir of dissolved oxygen perhaps in the semireducing environment of the flood plain lakes

  9. Stable isotope ratio mass spectrometry of nanogram quantities of boron and sulfur

    Wieser, Michael Eugene

    1998-09-01

    Instrumentation and analytical techniques were developed to measure isotope abundances from nanograms of sulfur and boron. Sulfur isotope compositions were determined employing continuous flow isotope ratio mass spectroscopy (CF-IRMS) procedures and AsS+ thermal ionization mass spectrometry techniques (AsS+-TIMS). Boron isotope abundances were determined by BO2/sp--TIMS. CF-IRMS measurements realized δ34S values from 10 μg sulfur with precisions of ±0.3/perthous. To extend sulfur isotope measurements to much smaller samples, a TIMS procedure was developed to measure 75As32S+ and 75As34S+ at masses 108 and 109 from 200 ng S on a Finnigan MAT 262 with an ion counter. This is possibly the smallest amount of sulfur which has been successfully analyzed isotopically. The internal precision of 32S/34S ratios measured by AsS+-TIMS was better than ±0.15 percent. δ34S-values calculated relative to the measured 32S/34S value of an IAEA AG2S standard (S-1) agreed with those determined by CF-IRMS to within ±3/perthous. The increasing sensitivity of S-isotope analyses permits hiterto impossible investigations e.g. sulfur in tree rings and ice cores. Boron isotope abundances were measured as BO2/sp- from 50 ng B using an older thermal ionization mass spectrometer which had been extensively upgraded including the addition of computer control electronics, sensitive ion current amplification and fiber optic data bus. The internal precisions of the measured 11B/10B ratios were ±0.15 percent and the precisions of δ11B values calculated relative to the accepted international standard (SRM-951) were ±3/perthous. Two applications of boron isotope abundance variations were initiated (1) ground waters of Northern Alberta and (2) coffee beans in different regions of the world. In the first it was demonstrated that boron isotopes could be used to trace boron released during steam injection of oil sands into the surrounding environment. Data from the second study suggest that boron

  10. Isotope Fractionation During N Mineralization and the N Isotope Composition of Terrestrial Ecosystem N Pools

    Dijkstra, P.; Schwartz, E.; Hungate, B. A.; Hart, S. C.

    2008-12-01

    It has been an open question for several decades whether N mineralization is a fractionating process. This question is important for N cycling in terrestrial ecosystems because even a small fractionation during N mineralization could potentially have a large influence on the N isotope composition of other ecosystem N pools. Fractionation during N mineralization should result in a difference between the N isotope composition of the soil microorganisms, that of its substrates, and products. We analyzed the N isotope composition of the soil microbial biomass in a variety of ecosystems, and found that it was 15N enriched compared to that of other soil N pools, such as soil soluble, organic and inorganic N (Dijkstra et al. 2006a,b). We observed a negative correlation between the 15N enrichment of the microorganisms and the relative C and N availability for soil from ecosystems in Hawaii and Arizona, across a broad range of climates, grasslands and forests, and more than four million years of ecosystem development. This suggests that during N dissimilation (and associated transaminations) and N export, the lighter 14N N isotope is preferentially removed in a manner similar to that proposed for animals and ectomycorrhizae. This was further confirmed by the positive correlation between microbial 15N enrichment and net N mineralization rate (Dijkstra et al. 2008, Ecology Letters 11: 389-397) and by culture experiments with Escherichia coli (Collins et al. 2008). Since mineralization is the largest flux of N in ecosystems, fractionation during N mineralization has the potential to influence the N isotope composition of other N pools, such as inorganic N, plant N and soil organic matter N. We demonstrate that the N isotope compositions of these ecosystem N pools exhibit differences that are consistent with fractionation during N mineralization. Our results show that the N isotope composition can be used as a measure to trace N mineralization and decomposition in ecosystems

  11. Age-abundance relationships for neutral communities

    Danino, Matan; Shnerb, Nadav M.

    2015-10-01

    Neutral models for the dynamics of a system of competing species are often used to describe a wide variety of empirical communities. These models are used in many situations, ranging from population genetics and ecological biodiversity to macroevolution and cancer tumors. One of the main issues discussed within this framework is the relationships between the abundance of a species and its age. Here we provide a comprehensive analysis of the age-abundance relationships for fixed-size and growing communities. Explicit formulas for the average and the most likely age of a species with abundance n are given, together with the full probability distribution function. We further discuss the universality of these results and their applicability to the tropical forest community.

  12. Estimating the relationship between abundance and distribution

    Rindorf, Anna; Lewy, Peter

    2012-01-01

    Numerous studies investigate the relationship between abundance and distribution using indices reflecting one of the three aspects of distribution: proportion of area occupied, aggregation, and geographical range. Using simulations and analytical derivations, we examine whether these indices...... based on Euclidean distance to the centre of gravity of the spatial distribution. Only the proportion of structurally empty areas, Lloyds index, and indices of the distance to the centre of gravity of the spatial distribution are unbiased at all levels of abundance. The remaining indices generate...... relationships between abundance and distribution even in cases where no underlying relationships exists, although the problem decreases for measures derived from Lorenz curves when samples contain more than four individuals on average. To illustrate the problem, the indices are applied to juvenile North Sea cod...

  13. Unprecedented accurate abundances: signatures of other Earths?

    Melendez, J; Gustafsson, B; Yong, D; Ramírez, I

    2009-01-01

    For more than 140 years the chemical composition of our Sun has been considered typical of solar-type stars. Our highly differential elemental abundance analysis of unprecedented accuracy (~0.01 dex) of the Sun relative to solar twins, shows that the Sun has a peculiar chemical composition with a ~20% depletion of refractory elements relative to the volatile elements in comparison with solar twins. The abundance differences correlate strongly with the condensation temperatures of the elements. A similar study of solar analogs from planet surveys shows that this peculiarity also holds in comparisons with solar analogs known to have close-in giant planets while the majority of solar analogs without detected giant planets show the solar abundance pattern. The peculiarities in the solar chemical composition can be explained as signatures of the formation of terrestrial planets like our own Earth.

  14. 15N and 13C abundances in marine environments with emphasis on biogeochemical structure of food networks

    Distributions of δ15N and δ13C for biogenic substances in the Antarctic Ocean and in the Otsuchi River estuary in Japan were investigated to construct isotope biogeochemical framework for assessing marine ecosystems. The isotopic compositions of phytoplankton were particularly low in the Antarctic Ocean. High nitrate and CO2 concentrations in the surface sea waters, and the low light intensity seem to enhance the kinetic isotope fractionations that preferred the depletion of 15N and 13C in the algal body. A clear-cut linear relationship between animal δ15N and its trophic level was obtained in the Antarctic system. In the estuary, the variation of isotope ratios were principally governed by the mixing of land-derived organic matter, marine phytoplankton, and seagrasses. A food-chain effect of 15N enrichment was also confirmed. An isotopically ordered structure was presented for a marine estuarine ecosystem. The isotopic abundances in a food network vary mainly because of the variation in 15N and 13C contents of primary producers grown under different environmental conditions and because of the enrichment of 15N along food chains. (author)

  15. Beryllium Abundances in Solar Mass Stars

    Krugler, J. A.; Boesgaard, A. M.

    2008-08-01

    Light element abundance analysis allows for a deeper understanding of the chemical composition of a star beneath its surface. Beryllium provides a probe down to 3.5×106 K, where it fuses with protons. In this study, Be abundances were determined for 52 F and G dwarfs selected from a sample of local thin disc stars. These stars were selected by mass to range from 0.9 to 1.1 M⊙. They have effective temperatures from 5600 to 6400 K, and their metallicities [Fe/H]=-0.65 to +0.11. The data were taken with the Keck HIRES instrument and the Gecko spectrograph on the Canada France Hawaii Telescope. The abundances were calculated via spectral synthesis and were analyzed to investigate the Be abundance as a function of age, temperature, metallicity, and its relation to the lithium abundance for this narrow mass range. Be is found to decrease linearly with metallicity down to [Fe/H]˜-4.0 with slope 0.86 ± 0.02. The relation of the Be abundance to effective temperature is dependent upon metallicity, but when metallicity effects are taken into account, there is a spread ˜1.2 dex. We find a 1.5 dex spread in A(Be) when plotted against age, with the largest spread occurring from 6-8 Gyr. The relation with Li is found to be linear with slope 0.36 ± 0.06 for the temperature regime of 5900-6300 K.

  16. Laser Spectroscopic Measurement of Helium Isotope Ratios

    Wang, L B; Holt, R J; Lu, Z T; O'Connor, T P; Sano, Y; Sturchio, N C

    2003-01-01

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of 3He/4He = 10^-7 - 10^-5. The resonant absorption of 1083 nm laser light by the metastable 3He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of 4He was measured by a direct absorption technique. The results on three different samples extracted from the atmosphere and commercial helium gas were in good agreement with values obtained with mass spectrometry. The achieved 3-sigma detection limit of 3He in helium is 4 x 10^-9. This demonstration required a 200 micro-L STP sample of He. The sensitivity can be further improved, and the required sample size reduced, by several orders of magnitude with the addition of cavity enhanced spectroscopy.

  17. Laser spectroscopic measurement of helium isotope ratios

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of 3He/4He = 10-7--10-5. The resonant absorption of 1083 nm laser light by the metastable 3He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of 4He was measured by a direct absorption technique. The results on three different samples extracted from the atmosphere and commercial helium gas were in good agreement with values obtained with mass spectrometry. The achieved 3σ detection limit of 3He in helium is 4 x 10-9. This demonstration required a 200 μL STP sample of He. The sensitivity can be further improved, and the required sample size reduced, by several orders of magnitude with the addition of cavity enhanced spectroscopy.

  18. Metal Abundances in Hot DO White Dwarfs

    Werner, K; Ringat, E; Kruk, J W

    2012-01-01

    The relatively high abundance of carbon in the hot DO white dwarf RE0503-289 indicates that it is a descendant of a PG1159 star. This is corroborated by the recent detection of the extremely high abundances of trans-Fe elements which stem from s-process nucleosynthesis in the precursor AGB star, dredged up by a late He-shell flash and possibly amplified by radiative levitation. On the other hand, the hottest known DO white dwarf, KPD0005+5106, cannot have evolved from a PG1159 star but represents a distinct He-rich evolutionary sequence that possibly originates from a binary white dwarf merger.

  19. New isotope 265Bh

    A new isotope 265Bh was produced and identified at the Sector Focus Cyclotron of the Heavy Ion Research Facility in Lanzhou. This experiment was performed via the reaction of an 243Am target with 168 MeV 26Mg ions. Identification was made by observation of correlated α -particle decays between the new isotope 265Bh and its 261Db and 257Lr daughter nuclei using a set of rotating-wheels system. A total of 8 correlated decay events of 265Bh and 4 decay events of 264Bh were observed. 265Bh decays with a 0.94 -0.31+0.70 s half-life by emission of α-particles with an average energy of 9.24 ±0.05 MeV. The half-life and α decay energy of 265Bh from this experiment are in agreement with theoretical predictions. (orig.)

  20. Cyclotrons for isotope production

    Cyclotrons continue to be efficient accelerators for radioisotope production. In recent years, developments in the accelerator technology have greatly increased the practical beam current in these machines while also improving the overall system reliability. These developments combined with the development of new isotopes for medicine and industry, and a retiring of older machines indicates a strong future for commercial cyclotrons. In this paper we will survey recent developments in the areas of cyclotron technology, and isotope production, as they relate to the new generation of commercial cyclotrons. We will also discuss the possibility of systems capable of extracted energies up to 100 MeV and extracted beam currents of up to 2.0 mA. (author). 6 refs., 2 tabs., 3 figs

  1. Isotope enrichment systems

    This patent provides a process for concentrating the heavy isotope of at least one element of the class consisting of hydrogen and oxygen by the dual temperature exchange of the heavy and light isotopes of the element between two separable fluids containing said element. One of the fluids is in the gaseous phase and the other in the liquid phase. The liquid phase is provided as a solution consisting essentially in minor molar proportion, of water and in major molar proportion, of material selected from the class consisting of the water miscible organic hydroxy and/or carboxy compounds which have a ratio of carbon atoms to their alcoholic and acidic hydroxyl groups not greater than 2

  2. Daily Variation of Isotope Ratios in Mars Atmospheric Carbon Dioxide

    Livengood, Timothy A.; Kostiuk, Theodor; Kolasinski, John R.; Hewagama, Tilak; Henning, Wade G.; Sornig, Manuela; Stangier, Tobias; Krause, Pia; Sonnabend, Guido; Mahaffy, Paul R.

    2014-11-01

    The atmosphere of Mars has been shown by ground based high-resolution infrared spectroscopy and in situ measurements with the Phoenix lander and Mars Science Laboratory Curiosity rover to be enriched in C and O heavy isotopes, consistent with preferential loss of light isotopes in eroding Mars’ primordial atmosphere. The relative abundance of heavy isotopes, combined with contemporary measurements of loss rates to be obtained with MAVEN, will enable estimating the primordial atmospheric inventory on Mars. IR spectroscopy of Mars collected in May 2012 as well as in March and May of 2014 from the NASA IRTF has resolved transitions of all three singly-substituted minor isotopologues of carbon dioxide in addition to the normal isotope, enabling remote measurements of all the carbon and oxygen isotope ratios as a function of latitude, longitude, and time of day. Earlier measurements obtained in October 2007 demonstrated that the relative abundance of O-18 increased linearly with increasing surface temperature over a relatively warm early-afternoon temperature range, but did not extend far enough to inspect the effect of late-afternoon cooling. These results imply that isotopically enriched gas is sequestered overnight when surface temperature is minimum and desorbs through the course of the day as temperature increases. Current spectroscopic constants indicate that the peak isotopic enrichment could be significantly greater than what has been measured in situ, apparently due to sampling the atmosphere at different time of day and surface temperature. The observing runs in 2012 and 2014 measured O-18 enrichment at several local times in both morning and afternoon sectors as well as at the subsolar, equatorial, and anti-subsolar latitudes. The two runs in 2014 have additionally observed O-17 and C-13 transitions in the morning sector, from local dawn to noon. These observations include a limited sampling of measurements over Gale Crater, which can be compared with

  3. Mars and earth - Origin and abundance of volatiles

    Anders, E.; Owen, T.

    1977-01-01

    An investigation is conducted concerning the factors which are responsible for the tenuous nature of the Martian atmosphere in comparison to the terrestrial atmosphere, taking into account new data obtained in connection with the Viking missions. It is found that Mars was poor in volatiles from the start and fell further behind earth by less complete outgassing, by extensive retrapping, and by the partial loss of lighter gases. Attention is given to noble gases on earth and Mars, the condensation of noble gases and other volatiles, the sources of earth's volatiles, the bulk composition of earth, the release of volatiles from earth, clues to the volatile endowment of Mars, an abundance table for Mars, a comparison of terrestrial and Martian conditions, isotopic data on noble gases, xenon-129 on Mars and earth, possibilities concerning the loss of an early Martian atmosphere, the evolution of the atmosphere of Mars, conditions in the case of planet Venus, and the reasons for the poorness of small planets in volatiles.

  4. Scale-dependent linkages between nitrate isotopes and denitrification in surface soils: implications for isotope measurements and models.

    Hall, Steven J; Weintraub, Samantha R; Bowling, David R

    2016-08-01

    Natural abundance nitrate (NO3 (-)) isotopes represent a powerful tool for assessing denitrification, yet the scale and context dependence of relationships between isotopes and denitrification have received little attention, especially in surface soils. We measured the NO3 (-) isotope compositions in soil extractions and lysimeter water from a semi-arid meadow and lawn during snowmelt, along with the denitrification potential, bulk O2, and a proxy for anaerobic microsites. Denitrification potential varied by three orders of magnitude and the slope of δ(18)O/δ(15)N in soil-extracted NO3 (-) from all samples measured 1.04 ± 0.12 (R (2) = 0.64, p nitrification that was partially overprinted by denitrification. Mean NO3 (-) isotopes in lysimeter water differed from soil extractions by up to 19 ‰ in δ(18)O and 12 ‰ in δ(15)N, indicating distinct biogeochemical processing in relatively mobile water versus soil microsites. This implies that NO3 (-) isotopes in streams, which are predominantly fed by mobile water, do not fully reflect terrestrial soil N cycling. Relationships between potential denitrification and δ(15)N of extracted NO3 (-) showed a strong threshold effect culminating in a null relationship at high denitrification rates. Our observations of (1) competing fractionation from nitrification and denitrification in redox-heterogeneous surface soils, (2) large NO3 (-) isotopic differences between relatively immobile and mobile water pools, (3) and the spatial dependence of δ(18)O/δ(15)N relationships suggest caution in using NO3 (-) isotopes to infer site or watershed-scale patterns in denitrification. PMID:27102809

  5. Dual isotope assays

    Dual isotope assays for thyroid function are performed by carrying out a radio-immunoassay for two of thyroxine (T4), tri-iodothyronine (T3), thyroid stimulating hormone (TSH), and thyroxine binding globulin (TBG), by a method wherein a version of one of the thyroid components, preferably T4 or T3 is labelled with Selenium-75 and the version of the other thyroid component is labelled with a different radionuclide, preferably Iodine-125. (author)

  6. Carbon isotopes in photosynthesis

    The efficiency of photosynthesis continues to interest biochemists, biologists, and plant physiologists. Scientists interested in CO2 uptake are concerned about the extent to which the uptake rate is limited by such factors as stomatal diffusion and the chemistry of the CO2 absorption process. The fractionation of carbon isotopes that occurs during photosynthesis is one of the most useful techniques for investigating the efficiency of CO2 uptake

  7. Photochemical separation of isotopes

    A process for the photochemical separation of carbon 13 and oxygen 18 uses 123.54 nm resonance radiation from a gaseous discharge containing Kr and an inert gas to excite selectively 13C16O, 12C18O, or both with no significant excitation of 12C16O. The excited molecules react with ground state CO to yield CO2 and C3O2. The isotopically-enriched products are removed from the reactants by condensation

  8. Isotopes and agriculture

    The agriculture is defined as the art of desturbing the ecosystems in economical terms with the minimum of irreversible damage. Man survival in the biosphere will depend on its ability of using four technologies - mechanization, fertilizers, irrigation and pest disease control. The isotopes are usefull to establish means of producing more food and to preserve it; and clains of unbearable damages to the ecosystems caused by fertilizers and pesticides are not true, are presented. (author)

  9. Stable isotope laser spectroscopy

    Becker, J. F.; Yaldaei, Ramil; Mckay, Christopher P.

    1989-01-01

    Recent advances in semiconductor laser technology have produced a reliable lightweight device ideally suited for a spacecraft high resolution molecular spectrometer. Lead-salt tunable diode lasers (TDL) emit in several spectral modes, each with a very narrow linewidth of -0.0003/cm. This spectral resolution is much narrower than typical Doppler broadened molecular linewidths in the mid-IR range. Thus it is possible to detect individual rotational lines within the vibrational band and measure their intensity, which can be used to determine gas concentration. The narrow spectral lines of any impurity gas tend to lie between the narrow lines of the gas of interest. This represents a major advantage over the accepted gas chromatograph mass spectrometer (GCMS) technique for measuring gas concentrations and isotope ratios. The careful and extensive gas purification procedures required to remove impurities for reliable GCMS measurements will not be required for an IR laser gas analysis. The infrared laser gas analysis technique is being developed to measure stable isotopic ratios of gases such as CO2, CH4, N2O, and NH3. This will eventually lead to development of instruments capable of in situ istopic measurements on planets such as Mars. The carbon (C-12, C-13) isotope ratio is indicative of the type of carbon fixation mechanisms (e.g., photosynthesis, respiration) in operation on a planet, while the nitrogen (N-14, N-15) isotope ratio can probably be used to date nitrogen-bearing Martian samples. The absorbance ratio of two adjacent lines of CO2 in the 2300/cm (4.3 micron) region of the spectrum was measured. The precision of the measurement is presently better than 1 percent and significant improvement is anticipated as rapid sweep-integration techniques and computer controlled data acquistion capabilities are incorporated.

  10. The Chlorine Isotopic Composition Of Lunar UrKREEP

    Barnes, J. J.; Tartese, R.; Anand, M.; McCubbin, F. M.; Neal, C. R.; Franchi, I. A.

    2016-01-01

    Since the long standing paradigm of an anhydrous Moon was challenged there has been a renewed focus on investigating volatiles in a variety of lunar samples. Numerous studies have examined the abundances and isotopic compositions of volatiles in lunar apatite, Ca5(PO4)3(F,Cl,OH). In particular, apatite has been used as a tool for assessing the sources of H2O in the lunar interior. However, current models for the Moon's formation have yet to fully account for its thermal evolution in the presence of H2O and other volatiles. For ex-ample, in the context of the lunar magma ocean (LMO) model, it is anticipated that chlorine (and other volatiles) should have been concentrated in the late-stage LMO residual melts (i.e., the dregs enriched in incompatible elements such as K, REEs (Rare Earth Elements), and P, collectively called KREEP, and in its primitive form - urKREEP, given its incompatibility in mafic minerals like olivine and pyroxene, which were the dominant phases that crystallized early in the cumulate pile of the LMO. When compared to chondritic meteorites and terrestrial rocks, lunar samples have exotic chlorine isotope compositions, which are difficult to explain in light of the abundance and isotopic composition of other volatile species, especially H, and the current estimates for chlorine and H2O in the bulk silicate Moon (BSM). In order to better understand the processes involved in giving rise to the heavy chlorine isotope compositions of lunar samples, we have performed a comprehensive in situ high precision study of chlorine isotopes in lunar apatite from a suite of Apollo samples covering a range of geochemical characteristics and petrologic types.

  11. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    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. Trace Element Abundances in an Unusual Hibonite-Perovskite Refractory Inclusion from Allende

    Mane, Prajkta; Wadhwa, M.; Keller, L. P.

    2013-01-01

    Calcium-aluminum-rich refractory inclusions (CAIs) are thought to be the first-formed solids in the Solar protoplanetary disk and can provide information about the earliest Solar System processes (e.g., [1]). A hibonite-perovskitebearing CAI from the Allende CV3 chondrite (SHAL, [2]) contains a single of 500 micrometers hibonite grain and coarse-grained perovskite. The mineralogy and oxygen isotopic composition of this CAI shows similarities with FUN inclusions, especially HAL [2]. Here we present trace element abundances in SHAL.

  13. HETEROGENEITY in 12CO/13CO ABUNDANCE RATIOS TOWARD SOLAR-TYPE YOUNG STELLAR OBJECTS

    Smith, RL; Pontoppidan, KM; Young, ED; Morris,, Andrew P

    2015-01-01

    © 2015. The American Astronomical Society. All rights reserved.. This study reports an unusual heterogeneity in [12C16O]/[13C16O] abundance ratios of carbon monoxide observed in the gas phase toward seven ∼solar-mass young stellar objects (YSOs) and three dense foreground clouds in the nearby star-forming regions, Ophiuchus, Corona Australis, Orion, and Vela, and an isolated core, L43. Robust isotope ratios were derived using infrared absorption spectroscopy of the 4.7 μm fundamental and 2.3 ...

  14. Stable isotopes' as trophic tracers: combining field sampling and manipulative labelling of food resources for macrobenthos

    Herman, P.M.J.; Middelburg, J.J.; Widdows, J.; Lucas, C.M.; Heip, C.H.R.

    2000-01-01

    We combined 3 different approaches to determine the relative importance of microphytobenthos production as food for intertidal macrobenthic animals: (1) the natural abundance of stable-isotope ratios of carbon and nitrogen, (2) an in situ deliberate tracer addition of C-13-bicarbonate, which was tra

  15. Light induced drift: a possible mechanism of separation of isotopes by laser excitation

    A comprehensive review of the literature on the effect of light induced drift and its exploitation in the separation of isotopes, both in atomic and molecular forms, is presented. An experimental scheme based on this effect to separate S33, with a natural abundance of ∼0.76%, from SF6 has also been worked out. (author)

  16. Constraints on the creation of a HIMU-Like isotopic reservoir beneath New Zealand

    van der Meer, Quinten; Waight, Tod Earle; Scott, James

    2013-01-01

    intrusion of mafic dikes (~88 to 68 Ma). Subsequently, Zealandia has been punctuated by volumetrically minor, intermittent yet widespread intraplate magmatism from ~100 Ma through to recent times. This magmatism has typical OIB-like trace element abundances and radiogenic isotope compositions that trend...

  17. Cosmic Ray Helium Isotopes From 0.2 to 3.6 GeV/nucleon

    Reimer, O.; Hof, M.; Menn, W.;

    1996-01-01

    The abundances of cosmic ray helium isotopes were measured by the IMAX balloon-borne magnet spectrometer during a flight in July, 1992. A high-resolution time-of-flight system and two silica aerogel Cherenkov counters were used in conjunction with a drift-chamber/MWPC-tracking system to determine...

  18. Water enriched in the rare stable isotopes : Preparation, measurement and applications

    Faghihi, Vahideh

    2016-01-01

    The subject of this thesis is water with increased abundances of the rare stable isotopes 2H and 18O (and to some extent also 17O). Such artificially enriched (or "labelled") waters are often used in biomedicine, for establishing the total amount of body water (and thus body composition) of humans a

  19. Non-Salmonid Abundance - Line Features [ds186

    California Department of Resources — The CalFish Abundance Database contains a comprehensive collection of anadromous fisheries abundance information. The "Other Fish" category contains data collected...

  20. A Comparison of ACE Measurements of Galactic Cosmic-Ray Abundances and Energy Spectra for Two Successive Solar Minima

    J. Lavé; Binns, W. R.; Cummings, A. C.; de Nolfo, G. A.; Israel, M. H.; Leske, R. A.; Mewaldt, R.A; Stone, E. C.; von Rosenvinge, T. T.; Wiedenbeck, M. E.

    2009-01-01

    Using current solar minimum measurements from the Cosmic Ray Isotope Spectrometer (CRIS) onboard the Advanced Composition Explorer (ACE), we report the observed elemental abundances and energy spectra for C, O, Si, and Fe in the energy range of ~50-500MeV/nucleon. These measurements are compared to prior CRIS observations for the 1997-98 solar minimum period, when the solar magnetic field was of the opposite polarity. By April 2009, the current solar minimum intensities for each of the ...

  1. Morphology Composition Isotopes: Recent Results from Observations

    Schulz, R.

    2008-07-01

    This article presents some recent imaging and spectroscopic observations that led to results which are significant for understanding the properties of comet nuclei. The coma morphology and/or composition were investigated for 12 comets belonging to different dynamical classes. The data analysis showed that the coma morphology of three non-periodic comets is not consistent with the general assumption that dynamically new comets still have a relatively uniform nucleus surface and therefore do not exhibit gas and/or dust jets in their coma. The determination of carbon and nitrogen isotopic ratios revealed the same values for all comets investigated at various heliocentric distances. However, the relative abundance of the rare nitrogen isotope 15N is about twice as high as in the Earth’s atmosphere. Observations of comets at splitting events and during outbursts led to indications for differences between material from the nucleus surface and the interior. The monitoring of the induced outburst of 9P/Temple revealed that under non-steady state conditions the fast disintegration of species is detectable.

  2. Nickel isotopes and methanogens

    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

  3. Nitrogen balance and 15N abundance in a long-term organic matter experiment

    In along-term field experiment on a clay loam soil at Uppsala, Sweden, changes of nitrogen contents and the natural abundance of 15N in the topsoils receiving various organic amendments at the rate of 2000 kg C ha-1 y-1 and different rates of nitrogen were studied. Cropping resulted in clearly lower N-losses from the topsoil (0-20 cm) compared to the bare fallow plots. Green manure, animal manure and sewage sludge increased the Nt-inventory significantly and 15N abundances were clearly affected by N-input differing in isotopic signature through the amendments. A N-balance and half-lives of the introduced nitrogen were calculated. Refs. 7 (author)

  4. Amendment of the Measurement of Low Abundance 236U by Mass Spectrometry

    The low abundance isotope 236U is easily disturbed by strong peak tails in the measurement of Mass Spectrometry. So, the measurement of 236U is amended with the Background Amendment (BGA) tail calibration method and the dynamic background method. BGA method was used to measure the signal at 235.5 and 236.5 mass number, these signal could be regarded as strong peak tails which was eliminated in the measurement data. When 236U abundance was low, BGA calibration method had good effect, the emendation to measurement reached 2.24%, the amended value was more close to nominal value, and the effect of dynamic background amendment method is not significant. (authors)

  5. Low temperature Rosseland opacities with varied abundances of carbon and nitrogen

    Lederer, Michael T

    2008-01-01

    We provide low temperature opacity data that incorporate varied abundances of the elements carbon and nitrogen. In the temperature range that we focus at, molecules are the dominant opacity source. Our dataset spans a large metallicity range and shall deliver the necessary input data for stellar evolution models as well as other applications. We conduct chemical equilibrium calculations in order to evaluate the partial pressures of neutral atoms, ions and molecules. Based on a large dataset containing atomic line and continuum data, and, most importantly, a plethora of molecular lines, we subsequently calculate Rosseland mean opacity coefficients. This is done not only for a number of different metallicities, but also for varied abundances of the isotopes 12C and 14N at each metallicity. The molecular data comprise the main opacity sources at either an oxygen-rich or carbon-rich chemistry. We tabulate the opacity coefficients as a function of temperature and, basically, density. Already within a certain chemi...

  6. North Sea Elasmobranchs: distribution, abundance and biodiversity

    Daan, N.; Heessen, H.J.L.; Hofstede, ter R.

    2005-01-01

    Based on data from various international and national surveys, an overview is given of the fine-scale distribution (resolution of 20¿longitude * 10¿ latitude; ¿ 10*10 nm) and trends in abundance of elasmobranch species reported from the North Sea. Presence-absence maps are produced based on 4 survey

  7. Heavy element abundances and massive star formation

    Wang, Boqi; Silk, Joseph

    1993-01-01

    The determination of the stellar initial mass function (IMF) remains a great challenge in astronomy. In the solar neighborhood, the IMF is reasonable well determined for stellar masses from about 0.1 to 60 solar mass. However, outside the solar neighborhood, the IMF is poorly known. Among those frequently discussed arguments favoring a different IMF outside the solar neighborhood are the estimated time to consume the remaining gas in spiral galaxies, and the high rate of forming massive stars in starburst galaxies. An interesting question then is whether there may be an independent way of testing possible variations in the IMF. Indeed, the heavy elements in the interstellar medium are mostly synthesized in massive stars, so increasing, or decreasing, the fraction of massive stars naturally leads to a variation in the heavy element yield, and thus, the metallicity. The observed abundance should severely constrain any deviations of the IMF from the locally determined IMF. We focus on element oxygen, which is the most abundant heavy element in the interstellar medium. Oxygen is ejected only by massive stars that can become Type 1 supernovae, and the oxygen abundance is, therefore, a sensitive function of the fraction of massive stars in the IMF. Adopting oxygen enables us to avoid uncertainties in Type 1 supernovae. We use the nucleosynthesis results to calculate the oxygen yield for given IMF. We then calculate the oxygen abundance in the interstellar medium assuming instantaneous recycling of oxygen.

  8. The Galactic Thick Disk Stellar Abundances

    Prochaska, J X; Carney, B W; McWilliam, A; Wolfe, A M; Prochaska, Jason X.; Naumov, Sergei O.; Carney, Bruce W.; William, Andrew Mc; Wolfe, Arthur M.

    2000-01-01

    We present first results from a program to measure the chemical abundances of a large (N>30) sample of thick disk stars with the principal goal of investigating the formation history of the Galactic thick disk. Our analysis confirms previous studies of O and Mg in the thick disk stars which reported enhancements in excess of the thin disk population. Furthermore, the observations of Si, Ca, Ti, Mn, Co, V, Zn, Al, and Eu all argue that the thick disk population has a distinct chemical history from the thin disk. With the exception of V and Co, the thick disk abundance patterns match or tend towards the values observed for halo stars with [Fe/H]~-1. This suggests that the thick disk stars had a chemical enrichment history similar to the metal-rich halo stars. With the possible exception of Si, the thick disk abundance patterns are in excellent agreement with the chemical abundances observed in the metal-poor bulge stars suggesting the two populations formed from the same gas reservoir at a common epoch. We disc...

  9. The Abundance of Large Arcs From CLASH

    Xu, Bingxiao; Postman, Marc; Meneghetti, Massimo; Coe, Dan A.; Clash Team

    2015-01-01

    We have developed an automated arc-finding algorithm to perform a rigorous comparison of the observed and simulated abundance of large lensed background galaxies (a.k.a arcs). We use images from the CLASH program to derive our observed arc abundance. Simulated CLASH images are created by performing ray tracing through mock clusters generated by the N-body simulation calibrated tool -- MOKA, and N-body/hydrodynamic simulations -- MUSIC, over the same mass and redshift range as the CLASH X-ray selected sample. We derive a lensing efficiency of 15 ± 3 arcs per cluster for the X-ray selected CLASH sample and 4 ± 2 arcs per cluster for the simulated sample. The marginally significant difference (3.0 σ) between the results for the observations and the simulations can be explained by the systematically smaller area with magnification larger than 3 (by a factor of ˜4) in both MOKA and MUSIC mass models relative to those derived from the CLASH data. Accounting for this difference brings the observed and simulated arc statistics into full agreement. We find that the source redshift distribution does not have big impact on the arc abundance but the arc abundance is very sensitive to the concentration of the dark matter halos. Our results suggest that the solution to the "arc statistics problem" lies primarily in matching the cluster dark matter distribution.

  10. Will Abundant Natural Gas Solve Climate Change?

    McJeon, H. C.; Edmonds, J.; Bauer, N.; Leon, C.; Fisher, B.; Flannery, B.; Hilaire, J.; Krey, V.; Marangoni, G.; Mi, R.; Riahi, K.; Rogner, H.; Tavoni, M.

    2015-12-01

    The rapid deployment of hydraulic fracturing and horizontal drilling technologies enabled the production of previously uneconomic shale gas resources in North America. Global deployment of these advanced gas production technologies could bring large influx of economically competitive unconventional gas resources to the energy system. It has been hoped that abundant natural gas substituting for coal could reduce carbon dioxide (CO2) emissions, which in turn could reduce climate forcing. Other researchers countered that the non-CO2 greenhouse gas (GHG) emissions associated with shale gas production make its lifecycle emissions higher than those of coal. In this study, we employ five state-of-the-art integrated assessment models (IAMs) of energy-economy-climate systems to assess the full impact of abundant gas on climate change. The models show large additional natural gas consumption up to +170% by 2050. The impact on CO2 emissions, however, is found to be much smaller (from -2% to +11%), and a majority of the models reported a small increase in climate forcing (from -0.3% to +7%) associated with the increased use of abundant gas. Our results show that while globally abundant gas may substantially change the future energy market equilibrium, it will not significantly mitigate climate change on its own in the absence of climate policies.

  11. Abundance of Terrestrial Planets by Microlensing

    Yock, Philip

    2000-01-01

    Terrestrial planets may be detected using the gravitational microlensing technique. This was demonstrated in the high magnification event MACHO-98-BLG-35. Observing strategies aimed at measuring the abundance of terrestrial planets are discussed, using both existing telescopes and planned telescopes.

  12. Quasar Elemental Abundances at High Redshifts

    Dietrich, M.; Hamann, F.; Shields, J. C.; Constantin, A.; Heidt, J.; Jaeger, K.; Vestergaard, Marianne; Wagner, S. J.

    2003-01-01

    framework of the most recent photoionization models to estimate the metallicity of the gas associated with the high-z quasars. Standard photoionization parameters and the assumption of secondary nitrogen enrichment indicate an average abundance of Z/Z_sol = 4 to 5 in the line emitting gas. Assuming a time...

  13. Actinide isotopic analysis system for Los Alamos Plutonium-Handling Facility

    This paper reports that inventory measurement of a sample's total plutonium and other actinides content by non-destructive assay is an important component of safeguarding special nuclear material. Gamma-ray spectromety measurements of relative isotopic abundances, coupled with a calorimetry measurement, can determine sample SNM content for inventory measurement. The Actinide Isotopic Analysis System (AIAS) is a newly developed two-detector gamma-ray spectrometry-based system that will determine isotopic ratios of Pu and U, Np, and Am abundances relative to plutonium for the Nuclear Material Storage Facility at Los Alamos National Laboratory. spectral analysis is performed using Multiple Group analysis (MGA) program or a customized version of the Group Analysis (GRPANL) computer program. The system can measure samples containing reactor grade plutonium, weapons grade plutonium, and plutonium enriched in either 238Pu or 242Pu (>50%). Software that controls the system is driven by a user-friendly menu of options

  14. Innovations in isotope techniques to enhance the evaluation and management of nutrient sources

    The increasing world population and the need to produce more food is putting increasing pressures on soil and water resources. Increasingly, studies of interactions between nutrients rather than single nutrient studies are becoming important as systems intensify and a wider range of nutrients is added. The incorporation of isotopes into these studies will greatly assist in understanding the driving forces that determine system productivity and sustainability. Studies of N dynamics have been greatly assisted by the use of the stable 15N, and studies of water, other nutrients, and C have also been assisted by the use of radioactive isotopes such as 3H, 14C, 32P, 35S and 86Rb. However, increasing restrictions on the use of radioactive substances are beginning to severely limit their availability for such studies. Stable isotopes such as 13C, 15N and 34S offer the prospect of replacing radioactive isotopes, or of their being used in combination with radioactive isotopes, to minimize the perceived risks and/or to allow the tracing of two components in the system. The innovative use of isotopes in plant-nutrient studies utilizing direct labelling with stable isotopes, multiple direct labelling with stable and/or radioactive isotopes and/or utilizing natural abundance, reverse dilution, or a combination of direct labelling and reverse dilution, are presented. (author)

  15. Chemical abundances and kinematics of barium stars

    de Castro, D. B.; Pereira, C. B.; Roig, F.; Jilinski, E.; Drake, N. A.; Chavero, C.; Silva, J. V. Sales

    2016-04-01

    In this paper we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scale height, radial velocities, abundances of the Na, Al, alpha-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. We found that the metallicities, the temperatures and the surface gravities for barium stars can not be represented by a single gaussian distribution. The abundances of alpha-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heavy-element abundance pattern as given by the ratio [s/Fe], we found that the barium stars present several degrees of enrichment. We also obtained the [hs/ls] ratio by measuring the photospheric abundances of the Ba-peak and the Zr-peak elements. Our results indicated that the [s/Fe] and the [hs/ls] ratios are strongly anti-correlated with the metallicity. Our kinematical analysis showed that 90% of the barium stars belong to the thin disk population. Based on their luminosities, none of the barium stars are luminous enough to be an AGB star, nor to become self-enriched in the s-process elements. Finally, we determined that the barium stars also follow an age-metallicity relation.

  16. Chemical abundances and kinematics of barium stars

    de Castro, D. B.; Pereira, C. B.; Roig, F.; Jilinski, E.; Drake, N. A.; Chavero, C.; Sales Silva, J. V.

    2016-07-01

    In this paper, we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scaleheight, radial velocities, abundances of the Na, Al, α-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. We found that the metallicities, the temperatures and the surface gravities for barium stars cannot be represented by a single Gaussian distribution. The abundances of α-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heavy-element abundance pattern as given by the ratio [s/Fe], we found that the barium stars present several degrees of enrichment. We also obtained the [hs/ls] ratio by measuring the photospheric abundances of the Ba-peak and the Zr-peak elements. Our results indicated that the [s/Fe] and the [hs/ls] ratios are strongly anticorrelated with the metallicity. Our kinematical analysis showed that 90 per cent of the barium stars belong to the thin disc population. Based on their luminosities, none of the barium stars are luminous enough to be an asymptotic giant branch star, nor to become self-enriched in the s-process elements. Finally, we determined that the barium stars also follow an age-metallicity relation.

  17. Therapeutic use of radioactive isotopes

    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...

  18. Laser Ablation Molecular Isotopic Spectrometry

    Russo, Richard E., E-mail: rerusso@lbl.gov [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Applied Spectra, Inc., 46661 Fremont Boulevard, Fremont, CA 94538 (United States); Bol' shakov, Alexander A. [Applied Spectra, Inc., 46661 Fremont Boulevard, Fremont, CA 94538 (United States); Mao Xianglei [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); McKay, Christopher P. [NASA-Ames Research Center, Moffett Field, CA 94035 (United States); Perry, Dale L.; Sorkhabi, Osman [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)

    2011-02-15

    A new method of performing optical isotopic analysis of condensed samples in ambient air and at ambient pressure has been developed: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). The technique uses radiative transitions from molecular species either directly vaporized from a sample or formed by associative mechanisms of atoms or ions in a laser ablation plume. This method is an advanced modification of a known atomic emission technique called laser-induced breakdown spectroscopy (LIBS). The new method - LAMIS - can determine not only chemical composition but also isotopic ratios of elements in the sample. Isotopic measurements are enabled by significantly larger isotopic shifts found in molecular spectra relative to atomic spectra. Analysis can be performed from a distance and in real time. No sample preparation or pre-treatment is required. Detection of the isotopes of hydrogen, boron, carbon, and oxygen are discussed to illustrate the technique.

  19. Laser Ablation Molecular Isotopic Spectrometry

    Russo, Richard E.; Bol'shakov, Alexander A.; Mao, Xianglei; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman

    2011-02-01

    A new method of performing optical isotopic analysis of condensed samples in ambient air and at ambient pressure has been developed: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). The technique uses radiative transitions from molecular species either directly vaporized from a sample or formed by associative mechanisms of atoms or ions in a laser ablation plume. This method is an advanced modification of a known atomic emission technique called laser-induced breakdown spectroscopy (LIBS). The new method — LAMIS — can determine not only chemical composition but also isotopic ratios of elements in the sample. Isotopic measurements are enabled by significantly larger isotopic shifts found in molecular spectra relative to atomic spectra. Analysis can be performed from a distance and in real time. No sample preparation or pre-treatment is required. Detection of the isotopes of hydrogen, boron, carbon, and oxygen are discussed to illustrate the technique.

  20. Isotope effects in lattice dynamics

    The large number of available stable isotopes and well developed isotope separation technology have enabled growing crystals of C, LiH, ZnO, CuCl, CuBr, Cu2O, CdS, α-Sn, Ge, Si, etc. with a controlled isotope composition. Experimental and theoretical studies provide evidence that the isotope effect has an influence on the thermal, elastic, and vibrational properties of crystals. In this paper it is shown that in Ge and C crystals isotope effect causes only weak phonon scattering whereas in LiH the scattering potential changes are so strong that they lead to experimentally observable phonon localization. It is emphasized that a systematic description of isotope effects requires that anharmonicity be taken into account. (reviews of topical problems)