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Sample records for level isotope ratio

  1. Zinc Isotope Ratios as Indicators of Diet and Trophic Level in Arctic Marine Mammals.

    PubMed

    Jaouen, Klervia; Szpak, Paul; Richards, Michael P

    2016-01-01

    Carbon and nitrogen stable isotope ratios of bone collagen are an established method for dietary reconstruction, but this method is limited by the protein preservation. Zinc (Zn) is found in bioapatite and the isotopic compositions of this element constitute a very promising dietary indicator. The extent of fractionation of Zn isotopes in marine environments, however, remains unknown. We report here on the measurement of zinc, carbon and nitrogen isotopes in 47 marine mammals from the archaeological site of Arvik in the Canadian Arctic. We undertook this study to test and demonstrate the utility of Zn isotopes in recent mammal bone minerals as a dietary indicator by comparing them to other isotopic dietary tracers. We found a correlation between δ66Zn values and trophic level for most species, with the exception of walruses, which may be caused by their large seasonal movements. δ6Zn values can therefore be used as a dietary indicator in marine ecosystems for both modern and recent mammals.

  2. SPATIAL VARIABILITY IN MUSSELS USED TO ASSESS BASE LEVEL NITROGEN ISOTOPE RATIO IN FRESHWATER ECOSYSTEMS

    EPA Science Inventory

    Freshwater mussels have been used to establish base level nitrogen isotope ratio values ( 15N) used in trophic position and food web studies in freshwater ecosystems. In this study, we assess the variability introduced when using unionid mussels in this manner by investigating th...

  3. Fast Scanning Single Collector ICP-MS for Low Level Isotope Ratio Measurements

    NASA Astrophysics Data System (ADS)

    Newman, K.; Georg, B.

    2010-12-01

    Multiple collector (MC)-ICP-MS is recognized as a workhorse in the field of isotope ratio measurements. With its unrivalled precision, high sample throughput and multi-element coverage, MC-ICPMS has opened up new areas of study in earth, environmental and biological sciences. However, SC-ICP-MS is fit for purpose for many applications where sample amount is limited and fractionations are relatively large. To compensate for the inherent ion beam instability associated with the ICP ion source, fast scanning magnetic sector instruments are used. Here, we describe and discuss the use of the Nu Attom SC-ICP-MS for low level isotope ratio measurements. The Nu Attom is a double focusing magnetic sector mass spectrometer with unique fast scanning capabilities. Deflectors located at the entrance and exit of the flight tube are used to alter the effective magnet radius by changing the ion trajectory. This enables a fast electrostatic scan over a mass range of approximately 40%. In contrast to other fast scanning magnetic sector instruments, there is no change in the ion energy which may introduce additional mass bias effects. The Nu Attom also has fully adjustable source and collector slits. This facilitates measurements in medium mass resolution (R=1500-2500), whilst maintaining a flat topped peak necessary for precise isotope ratio measurements. The potential applications of the Nu Attom in isotope ratio measurements will be explored.

  4. Zinc Isotope Ratios as Indicators of Diet and Trophic Level in Arctic Marine Mammals

    PubMed Central

    Jaouen, Klervia; Szpak, Paul; Richards, Michael P.

    2016-01-01

    Carbon and nitrogen stable isotope ratios of bone collagen are an established method for dietary reconstruction, but this method is limited by the protein preservation. Zinc (Zn) is found in bioapatite and the isotopic compositions of this element constitute a very promising dietary indicator. The extent of fractionation of Zn isotopes in marine environments, however, remains unknown. We report here on the measurement of zinc, carbon and nitrogen isotopes in 47 marine mammals from the archaeological site of Arvik in the Canadian Arctic. We undertook this study to test and demonstrate the utility of Zn isotopes in recent mammal bone minerals as a dietary indicator by comparing them to other isotopic dietary tracers. We found a correlation between δ66Zn values and trophic level for most species, with the exception of walruses, which may be caused by their large seasonal movements. δ6Zn values can therefore be used as a dietary indicator in marine ecosystems for both modern and recent mammals. PMID:27010907

  5. Perfluorinated chemicals infiltrate ocean waters: link between exposure levels and stable isotope ratios in marine mammals.

    PubMed

    Van de Vijver, Kristin Inneke; Hoff, Philippe Tony; Das, Krishna; Van Dongen, Walter; Esmans, Eddy Louis; Jauniaux, Thierry; Bouquegneau, Jean-Marie; Blust, Ronny; de Coen, Wim

    2003-12-15

    This is the first study to report on concentrations of perfluorinated organochemicals (FOCs) in marine mammals stranded along the southern North Sea coast in relation to stable nitrogen and carbon isotope ratios (delta15N and delta13C). The presence of FOCs in top predators such as marine mammals would indicate a potential biomagnification of these compounds and their widespread occurrence. Liver and kidney tissues of nine marine mammal species have been sampled. Among all the measured FOCs compounds, PFOS (perfluorooctane sulfonate) was predominant in terms of concentration. The highest PFOS concentrations were found in the liver of harbor seal compared to white-beaked dolphin, harbor porpoise, gray seal, sperm whale, white-sided dolphin, striped dolphin, fin whale, and hooded seal. PFOS concentrations differed significantly between sexes and age classes in harbor porpoises. Stable isotope measurements (delta13C and delta15N) were used in this study to describe the behavior of contaminants in food webs. We found a significant (p < 0.05) linear relationship between PFOS concentrations in livers of harbor porpoises and both muscle delta13C and delta15N measurements. Harbor and gray seals and white-beaked dolphin, which displayed the highest trophic position, contained the highest PFOS levels, while offshore feeders such as sperm whales, fin whales, striped dolphin, and white-sided dolphin showed lower PFOS concentrations than inshore species.

  6. Determination of Plutonium Isotope Ratios at Very Low Levels by ICP-MS using On-Line Electrochemically Modulated Separations

    SciTech Connect

    Liezers, Martin; Lehn, Scott A; Olsen, Khris B; Farmer, Orville T; Duckworth, Douglas C

    2009-10-01

    Electrochemically modulated separations (EMS) are shown to be a rapid and selective means of extracting and concentrating Pu from complex solutions prior to isotopic analysis by inductively coupled plasma mass spectrometry (ICP-MS). This separation is performed in a flow injection mode, on-line with the ICP-MS. A three-electrode, flow-by electrochemical cell is used to accumulate Pu at an anodized glassy carbon electrode by redox conversion of Pu(III) to Pu (IV&VI). The entire process takes place in 2% v/v (0.46M) HNO3. No redox chemicals or acid concentration changes are required. Plutonium accumulation and release is redox dependent and controlled by the applied cell potential. Thus large transient volumetric concentration enhancements can be achieved. Based on more negative U(IV) potentials relative to Pu(IV), separation of Pu from uranium is efficient, thereby eliminating uranium hydride interferences. EMS-ICP-MS isotope ratio measurement performance will be presented for femtogram to attogram level plutonium concentrations.

  7. Stable isotope ratios in swale sequences of Lake Superior as indicators of climate and lake level fluctuations during the Late Holocene

    USGS Publications Warehouse

    Sharma, Shruti; Mora, G.; Johnston, J.W.; Thompson, T.A.

    2005-01-01

    Beach ridges along the coastline of Lake Superior provide a long-term and detailed record of lake level fluctuations for the past 4000 cal BP. Although climate change has been invoked to explain these fluctuations, its role is still in debate. Here, we reconstruct water balance by employing peat samples collected from swale deposits present between beach ridge sequences at two locations along the coastline of Lake Superior. Carbon isotope ratios for Sphagnum remains from these peat deposits are used as a proxy for water balance because the presence or absence of water films on Sphagnum controls the overall isotope discrimination effects. Consequently, increased average water content in Sphagnum produces elevated ??13C values. Two maxima of Sphagnum ??13C values interpreted to reflect wetter conditions prevailed from 3400 to 2400 cal BP and from about 1900 to 1400 cal BP. There are two relatively short drier periods as inferred from low Sphagnum ??13C values: one is centered at about 2300 cal BP, and one begins at 1400 cal BP. A good covariance was found between Sphagnum ??13C values and reconstructed lake-levels for Lake Michigan in which elevated carbon isotope values correlate well with higher lake levels. Based on this covariance, we conclude that climate exerts a strong influence on lake levels in Lake Superior for the past 4000 cal BP. ?? 2005 Elsevier Ltd. All rights reserved.

  8. Isotope ratio determination in boron analysis.

    PubMed

    Sah, R N; Brown, P H

    1998-01-01

    Traditionally, boron (B) isotope ratios have been determined using thermal ionization mass spectrometry (TIMS) and, to some extent, secondary ion mass spectrometry (SIMS). Both TIMS and SIMS use a high-resolution mass analyzer, but differ in analyte ionization methods. TIMS uses electrons from a hot filament, whereas SIMS employs an energetic primary ion beam of Ga+, Cs+, or O- for analyte ionization. TIMS can be used in negative or positive ion modes with high sensitivity and precision of B isotope ratio determination. However, isobaric interferences may be a problem, if the sample is not well purified and/or memory of the previous sample is not removed. Time-consuming sample preparation, analyte (B) purification, and sample determination processes limit the applications of TIMS for routine analyses. SIMS can determine B and its isotope ratio in intact solid samples without destroying them, but has poorer resolution and sensitivity than TIMS, and is difficult to standardize for biological samples. Development of plasma-source mass spectrometry (MS) enabled the determination of B concentration and isotope ratio without requiring sample purification. Commonly used plasma-source MS uses an Ar inductively coupled plasma (ICP) as an ionization device interfaced to a low-resolution quadrupole mass analyzer. The quadrupole ICP-MS is less precise than TIMS and SIMS, but is a popular method for B isotope ratio determination because of its speed and convenience. B determination by ICP-MS suffers no spectroscopic interferences. However, sample matrices, memory effects, and some instrument parameters may affect the accuracy and precision of B isotope ratio determination if adequate precautions are not taken. New generations of plasma-source MS instruments using high-resolution mass analyzers provide better sensitivity and precision than the currently used quadrupole ICP-MS. Because of the convenience and high sample throughput, the high-resolution ICP-MS is expected to be the

  9. Laser spectroscopic measurement of helium isotope ratios.

    SciTech Connect

    Wang, L.-B.; Mueller, P.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Sano, Y.; Sturchio, N.; Univ. of Illinois; Univ. of Tokyo; Univ. of Illinois at Chicago

    2003-06-13

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of {sup 3}He/{sup 4}He = 10{sup -7}--10{sup -5}. The resonant absorption of 1083 nm laser light by the metastable {sup 3}He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of {sup 4}He 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 {sup 3}He in helium is 4 x 10{sup -9}. This demonstration required a 200 {mu}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.

  10. Nicotine, acetanilide and urea multi-level 2H-, 13C- and 15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry.

    PubMed

    Schimmelmann, Arndt; Albertino, Andrea; Sauer, Peter E; Qi, Haiping; Molinie, Roland; Mesnard, François

    2009-11-01

    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 delta values of these reference materials should bracket the isotopic range of samples with unknown delta 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 delta13C and delta15N, 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: delta2H(nicotine) -162 to -45 per thousand, delta13C(nicotine) -30.05 to +7.72 per thousand, delta15N(nicotine) -6.03 to +33.62 per thousand; delta15N(acetanilide) +1.18 to +40.57 per thousand; delta13C(urea) -34.13 to +11.71 per thousand, delta15N(urea) +0.26 to +40.61 per thousand (recommended delta values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as

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

    USGS Publications Warehouse

    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

  12. Helium isotope ratios in Easter microplate basalts

    NASA Astrophysics Data System (ADS)

    Poreda, R. J.; Schilling, J. G.; Craig, H.

    1993-09-01

    He-3/He-4 ratios in Easter Microplate basalt glasses show clear evidence of the effects of a mantle plume. The East Rift of the microplate between 26 and 28 deg S, identified by La/Sm, Sr and Pb isotopes and ridge crest elevation as the region of maximum plume influence, has He-3/He-4 ratios spanning the entire range from 7.5 to 11.7 R(sub A). The Easter Microplate is the only section of the entire East Pacific Rise that is associated with a known `hotspot' track (mantle plume) and has elevated He-3/He-4 ratios. Although most of the West Rift basalts contain MORB helium (8.0 - 8.7 (R sub A)), the basalt closest to the East Rift has an elevated He-3/He-4 ratio (11.3 R(sub A)), consistent with a significant plume component. The diversity in isotopic signatures also indicates that homogenization of isotopic anomalies does not occur, even in this region of `super-fast' spreading. The overall He-3/He-4-Pb-206/Pb-204 and He-3/He-4-Sr-87/Sr-86 trends have positive correlations, although the high between the He and Sr isotope distribution is modeled in the context of a plume source-migrating ridge sink. During channeling of the plume toward the ridge, helium if preferentially lost from the center of the channeled plume, resulting in lower He/Pb and He/Sr concentration ratios in the high He-3/He-4 component. Mixing trajectories in He-Sr isotopic space between a LILE depleted asthenosphere and a variably degassed plume component provide a reasonably good fit to the data and may explain the isotope systematics of plume-ridge interactions in the context of modern theories of plume dynamics.

  13. Feasibility of Isotopic Measurements: Graphite Isotopic Ratio Method

    SciTech Connect

    Wood, Thomas W.; Gerlach, David C.; Reid, Bruce D.; Morgan, W. C.

    2001-04-30

    This report addresses the feasibility of the laboratory measurements of isotopic ratios for selected trace constituents in irradiated nuclear-grade graphite, based on the results of a proof-of-principal experiment completed at Pacific Northwest National Laboratory (PNNL) in 1994. The estimation of graphite fluence through measurement of isotopic ratio changes in the impurity elements in the nuclear-grade graphite is referred to as the Graphite Isotope Ratio Method (GIRM). Combined with reactor core and fuel information, GIRM measurements can be employed to estimate cumulative materials production in graphite moderated reactors. This report documents the laboratory procedures and results from the initial measurements of irradiated graphite samples. The irradiated graphite samples were obtained from the C Reactor (one of several production reactors at Hanford) and from the French G-2 Reactor located at Marcoule. Analysis of the irradiated graphite samples indicated that replicable measurements of isotope ratios could be obtained from the fluence sensitive elements of Ti, Ca, Sr, and Ba. While these impurity elements are present in the nuclear-grade graphite in very low concentrations, measurement precision was typically on the order of a few tenths of a percent to just over 1 percent. Replicability of the measurements was also very good with measured values differing by less than 0.5 percent. The overall results of this initial proof-of-principal experiment are sufficiently encouraging that a demonstration of GIRM on a reactor scale basis is planned for FY-95.

  14. Helium isotope ratios in Ethiopian Rift basalts

    NASA Astrophysics Data System (ADS)

    Scarsi, P.; Craig, H.

    1996-11-01

    Helium isotope ratios were measured in olivine and pyroxene phenocrysts from basalts of the Ethiopian Rift Valley and Afar Depression between 6° and 15°N and 37° and 43°E. 3He/4He ratios range from 6 to 17 times the atmospheric value (RA = 1.4 × 10-6), that is, from ratios less than typical MORB (depleted mantle) helium (R/RA= 8 ± 1) to ratios similar to high-3He hotspots and to the Yellowstone hotspot (R/RA= 16.5). The high 3He/4He ratios occur all along the Ethiopian Rift and well up into the Afar Depression, with a maximum value of 17.0 RA at 8°N in the Rift Axis and a high value of 14.2 RA in the central Tat'Ali sector of the Afar Depression. The ratios decrease to MORB-like values near the edge of the Red Sea, and to sub-MORB ratios (5-6 RA) at the northern end of the Rift (Zula Peninsula) and at the southern end, at lakes Abaya and Chamo. The Ethiopian Rift provides the only continental hotspot terrain in which helium isotope ratios can be compared in detail between volcanic lavas and associated geothermal and volcanic gases, a primary motivation for this work. Comparison with our previously measured ratios in fluids and gases (range 2-15 RA) shows excellent agreement in the areas sampled for both lavas and fluids, and indicates that high-temperature volcanic fluids can be used for establishing helium isotope signatures in such terrains. The high-3He values in both fluids and basalts show that a Primitive Mantle (PM) component is required and that a Lower Mantle High-3He plume is strongly involved as a driving force in the rifting process of the East African Rift System.

  15. Isotopic ratio measurements with ICP-MS

    SciTech Connect

    Russ, G.P. III; Bazan, J.M.

    1986-06-03

    An inductively-coupled-plasma source mass spectrometer (ICP-MS) has been used to measure the isotopic composition of U, Pb, Os, and B standards. Particular emphasis has been placed on uranium because of its nuclear and environmental interest and because of the availability of a well-characterized set of standards with a wide range of isotopic compositions. The precision and accuracy obtainable in isotope ratio measurements by ICP-MS depend on many factors including background, interferences, dead time, mass fractionation (bias), abundance sensitivity, and counting statistics. Which, if any, of these factors controls accuracy and precision depends on the type of sample being analyzed and the characteristics of the mass spectrometer. These issues are discussed in detail.

  16. Measuring Isotope Ratios Across the Solar System

    NASA Technical Reports Server (NTRS)

    Webster, Chris R.; Mahaffy, Paul R.

    2012-01-01

    Stable isotope ratios in C, H, N, O and S are powerful indicators of a wide variety of planetary geophysical processes that can identify origin, transport, temperature history, radiation exposure, atmospheric escape, environmental habitability and biology [1]. For the Allan Hills 84001 meteorite, for example, the (sup 1)(sup 3)C/(sup 1)(sup 2)C ratio identifies it as a Mars (SNC) meteorite; the ??K/??Ar ratio tells us the last time the rock cooled to solid, namely 4 Gya; isotope ratios in (sup 3)He, (sup 2)(sup 1)Ne and (sup 3)?Ar show it was in space (cosmic ray exposure) for 10-20 million years; (sup 1)?C dating that it sat in Antarctica for 13,000 years before discovery; and clumped isotope analysis of (sup 1)?O(sup 1)(sup 3)C(sup 1)?O in its carbonate that it was formed at 18+/-4 ?C in a near-surface aqueous environment [2]. Solar System Formation

  17. Calcium isotope ratios in animal and human bone

    NASA Astrophysics Data System (ADS)

    Reynard, L. M.; Henderson, G. M.; Hedges, R. E. M.

    2010-07-01

    Calcium isotopes in tissues are thought to be influenced by an individual's diet, reflecting parameters such as trophic level and dairy consumption, but this has not been carefully assessed. We report the calcium isotope ratios (δ 44/42Ca) of modern and archaeological animal and human bone ( n = 216). Modern sheep raised at the same location show 0.14 ± 0.08‰ higher δ 44/42Ca in females than in males, which we attribute to lactation by the ewes. In the archaeological bone samples the calcium isotope ratios of the herbivorous fauna vary by location. At a single site, the archaeological fauna do not show a trophic level effect. Humans have lower δ 44/42Ca than the mean site fauna by 0.22 ± 0.22‰, and the humans have a greater δ 44/42Ca range than the animals. No effect of sex or age on the calcium isotope ratios was found, and intra-individual skeletal δ 44/42Ca variability is negligible. We rule out dairy consumption as the main cause of the lower human δ 44/42Ca, based on results from sites pre-dating animal domestication and dairy availability, and suggest instead that individual physiology and calcium intake may be important in determining bone calcium isotope ratios.

  18. Raman scattering method and apparatus for measuring isotope ratios and isotopic abundances

    DOEpatents

    Harney, Robert C.; Bloom, Stewart D.

    1978-01-01

    Raman scattering is used to measure isotope ratios and/or isotopic abundances. A beam of quasi-monochromatic photons is directed onto the sample to be analyzed, and the resulting Raman-scattered photons are detected and counted for each isotopic species of interest. These photon counts are treated mathematically to yield the desired isotope ratios or isotopic abundances.

  19. Final Report on Isotope Ratio Techniques for Light Water Reactors

    SciTech Connect

    Gerlach, David C.; Gesh, Christopher J.; Hurley, David E.; Mitchell, Mark R.; Meriwether, George H.; Reid, Bruce D.

    2009-07-01

    The Isotope Ratio Method (IRM) is a technique for estimating the energy or plutonium production in a fission reactor by measuring isotope ratios in non-fuel reactor components. The isotope ratios in these components can then be directly related to the cumulative energy production with standard reactor modeling methods.

  20. How the oxygen isotope ratio of rain water influences the isotope ratio of chicken eggshell carbonate

    NASA Astrophysics Data System (ADS)

    Price, Gregory; Grimes, Stephen

    2015-04-01

    The stable oxygen isotope ratio of chicken eggshell carbonate was analysed from chicken eggs laid under free range, and organic farming regimes from across the UK. The eggshell carbonate oxygen isotope data shows a clear depletion in delta18O distribution from the southwest to the northeast. Although consistently offset by around 1 permil, the same isotopic distribution as that seen in eggshell carbonate is observed in the delta18O ratio of rainfall and groundwater from across the UK. This distribution is related to the Rayleigh distillation of rainfall driven by westerly winds across the UK landmass. The clear relationship observed between eggshell delta18O values and that of rainwater presumably reflects the nature of free range chickens which must be drinking locally derived rainwater and supplementing their diet and water intake with locally derived food. These results suggest that the oxygen isotope value of chicken eggshells can be used as a forensic tool to identify the locality that free range and organic eggs were laid within the UK. Furthermore, if suitable material is preserved in the archaeological and geological record then such a relationship can potentially be used to establish the oxygen isotope value of rainwater from which ancient and / or ancestral birds lived.

  1. Extreme oxygen isotope ratios in the early Solar System.

    PubMed

    Aléon, Jérôme; Robert, François; Duprat, Jean; Derenne, Sylvie

    2005-09-15

    The origins of the building blocks of the Solar System can be studied using the isotopic composition of early planetary and meteoritic material. Oxygen isotopes in planetary materials show variations at the per cent level that are not related to the mass of the isotopes; rather, they result from the mixture of components having different nucleosynthetic or chemical origins. Isotopic variations reaching orders of magnitude in minute meteoritic grains are usually attributed to stellar nucleosynthesis before the birth of the Solar System, whereby different grains were contributed by different stars. Here we report the discovery of abundant silica-rich grains embedded in meteoritic organic matter, having the most extreme 18O/16O and 17O/16O ratios observed (both approximately 10(-1)) together with a solar silicon isotopic composition. Both O and Si isotopes indicate a single nucleosynthetic process. These compositions can be accounted for by one of two processes: a single exotic evolved star seeding the young Solar System, or irradiation of the circumsolar gas by high energy particles accelerated during an active phase of the young Sun. We favour the latter interpretation, because the observed compositions are usually not expected from nucleosynthetic processes in evolved stars, whereas they are predicted by the selective trapping of irradiation products.

  2. ICP-MS for isotope ratio measurement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of stable isotopes in mineral nutrition research has become a fundamental aspect of conducting this research. A gradual transition has occurred, now virtually complete, from radioactive isotope studies to those using stable isotopes. Although primarily used in human research, mineral stable ...

  3. System and method for high precision isotope ratio destructive analysis

    DOEpatents

    Bushaw, Bruce A; Anheier, Norman C; Phillips, Jon R

    2013-07-02

    A system and process are disclosed that provide high accuracy and high precision destructive analysis measurements for isotope ratio determination of relative isotope abundance distributions in liquids, solids, and particulate samples. The invention utilizes a collinear probe beam to interrogate a laser ablated plume. This invention provides enhanced single-shot detection sensitivity approaching the femtogram range, and isotope ratios that can be determined at approximately 1% or better precision and accuracy (relative standard deviation).

  4. Flame ionization mass spectrometry--Isotope ratio determinations for potassium

    USGS Publications Warehouse

    Taylor, Howard E.; Garbarino, John R.; Koirtyohann, S.R.

    1991-01-01

    The air/acetylene flame provides a convenient ion source for the determination of potassium isotopic ratios by mass spectrometry. Unlike the argon inductively coupled plasma (ICP), the flame provides low background in the mass region of interest. Ion production is quite satisfactory for isotope ratio measurements at the micrograms per milliliter (μg/mL) level and slightly below, with 1 μg/mL potassium giving about 105counts/second at a nominal mass-to-charge ratio of 39. The detection limit for potassium was 2-3 nanograms per milliliter (ng/mL). The ratio of 41K/39K was measured with 0.5-1% relative standard deviation, and a 41K spike representing 0.2% of the total potassium was readily detected. Both signal levels and signal stability were improved by adding a second easily ionized element such as cesium to samples and standards. Alternatively, a cesium solution could be aspirated for about 1 minute between sample measurements to ensure signal stability.

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

    SciTech Connect

    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).

  6. Isotope ratios in Geochemistry - highest sensitivity and scan speed

    NASA Astrophysics Data System (ADS)

    Chemnitzer, Rene; Hamester, Meike

    2013-04-01

    The applications for trace elemental analysis are steadily increasing: beside the classical fields such as environmental and semiconductor analysis more and more interest for trace elemental analysis in food, geochemical analysis and material characterization can be observed, not to forget hot topics such as analysis of isotope ratios and nanoparticles. At the same time the requirements for lower detection limits, sample throughput, matrix robustness, and easy to use instruments are increasing. An important performance characteristic for ICP-MS is the sensitivity. The Bruker aurora Elite achieves a sensitivity of 1.5 GHz/ppm, which directly translates to smaller spot sizes when doing laser ablation in geochemical analyses, and with that avoiding counting statistical limitations in the single digit µm spot size range. In combination with shortest integration times of 0.1ms it comes close to an almost simultaneous measurement with a single-collector ICP-MS. At the same time, other important parameters such as low oxide ratios and abundance sensitivity are maintained, at the typical low levels of a quadrupole ICP-MS. The presentation will describe the layout of an ICP-MS designed for highest sensitivity and show by means of application examples like laser ablation ICP-MS and liquid analysis the performance for isotope ratio analyses.

  7. Cesium isotope ratios as indicators of nuclear power plant operations.

    PubMed

    Delmore, James E; Snyder, Darin C; Tranter, Troy; Mann, Nick R

    2011-11-01

    There are multiple paths by which radioactive cesium can reach the effluent from reactor operations. The radioactive (135)Cs/(137)Cs ratios are controlled by these paths. In an effort to better understand the origin of this radiation, these (135)Cs/(137)Cs ratios in effluents from three power reactor sites have been measured in offsite samples. These ratios are different from global fallout by up to six fold and as such cannot have a significant component from this source. A cesium ratio for a sample collected outside of the plant boundary provides integration over the operating life of the reactor. A sample collected inside the plant at any given time can be much different from this lifetime ratio. The measured cesium ratios vary significantly for the three reactors and indicate that the multiple paths have widely varying levels of contributions. There are too many ways these isotopes can fractionate to be useful for quantitative evaluations of operating parameters in an offsite sample, although it may be possible to obtain limited qualitative information for an onsite sample.

  8. Cesium Isotope Ratios as Indicators of Nuclear Power Plant Operations

    SciTech Connect

    Darin Snyder; James Delmore; Troy Tranter; Nick Mann; Michael Abbott; John Olson

    2011-11-01

    There are multiple paths by which radioactive cesium can reach the effluent from reactor operations. The radioactive 135Cs/137Cs ratios are controlled by these paths. In an effort to better understand the origin of this radiation, these 135Cs/137Cs ratios in effluents from three power reactor sites have been measured in offsite samples. These ratios are different from global fallout by up to six fold and as such cannot have a significant component from this source. A cesium ratio for a sample collected outside of the plant boundary provides integration over the operating life of the reactor. A sample collected inside the plant at any given time can be much different from this lifetime ratio. The measured cesium ratios vary significantly for the three reactors and indicate that the multiple paths have widely varying levels of contributions. There are too many ways these isotopes can fractionate to be useful for quantitative evaluations of operating parameters in an offsite sample, although it may be possible to obtain limited qualitative information for an onsite sample.

  9. Utilizing Isotopic Uranium Ratios in Groundwater Evaluations at NFSS

    SciTech Connect

    Rhodes, M.C.; Keil, K.G.; Frederick, W.T.; Papura, T.R.; Leithner, J.S.; Peterson, J.M.; MacDonell, M.M.

    2006-07-01

    The U.S. Army Corps of Engineers (USACE) Buffalo District is currently evaluating environmental contamination at the Niagara Falls Storage Site (NFSS) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) as part of its Formerly Utilized Sites Remedial Action Program (FUSRAP). The NFSS is located in the Town of Lewiston in western New York and has been used to store uranium-contaminated materials since 1944. Most of the radioactive materials are currently contained in an on-site structure, but past contamination remains in soil and groundwater. As a naturally occurring radionuclide, uranium is present in all groundwater. Because contamination levels at the site are quite low, it can be difficult to distinguish zones that have been impacted by the past releases from those at the high end of the natural background range. The differences in the isotopic ratio of uranium-234 (U-234) to uranium-238 (U-238) between natural groundwater systems and affected areas are being used in an innovative way to better define the nature and extent of groundwater contamination at NFSS. In natural groundwater, the ratio of U-234 to U-238 exceeds 1 due to the alpha particle recoil effect, in which U-234 is preferentially mobilized to groundwater from adjacent rock or soil. This process is very slow, and it can be hundreds to thousands of years before a measurable impact is seen in the isotopic ratio. Thus, as a result of the recoil effect, the ratio of U-234 to U-238 will be higher in natural groundwater than in contaminated groundwater. This means that if site releases were the source of the uranium being measured in groundwater at NFSS, the ratio of U-234 to U-238 would be expected to be very close to 1 (the same ratio that exists in wastes and soil at the site), because not enough time has elapsed for the alpha particle recoil effect to have significantly altered that ratio. From an evaluation of site and regional groundwater data, an isotopic ratio

  10. Stable carbon isotope ratios of ambient aromatic volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Kornilova, Anna; Huang, Lin; Saccon, Marina; Rudolph, Jochen

    2016-09-01

    Measurements of mixing ratios and stable carbon isotope ratios of aromatic volatile organic compounds (VOC) in the atmosphere were made in Toronto (Canada) in 2009 and 2010. Consistent with the kinetic isotope effect for reactions of aromatic VOC with the OH radical the observed stable carbon isotope ratios are on average significantly heavier than the isotope ratios of their emissions. The change of carbon isotope ratio between emission and observation is used to determine the extent of photochemical processing (photochemical age, [OH]dt) of the different VOC. It is found that [OH]dt of different VOC depends strongly on the VOC reactivity. This demonstrates that for this set of observations the assumption of a uniform [OH]dt for VOC with different reactivity is not justified and that the observed values for [OH]dt are the result of mixing of VOC from air masses with different values for [OH]dt. Based on comparison between carbon isotope ratios and VOC concentration ratios it is also found that the varying influence of sources with different VOC emission ratios has a larger impact on VOC concentration ratios than photochemical processing. It is concluded that for this data set the use of VOC concentration ratios to determine [OH]dt would result in values for [OH]dt inconsistent with carbon isotope ratios and that the concept of a uniform [OH]dt for an air mass has to be replaced by the concept of individual values of an average [OH]dt for VOC with different reactivity.

  11. Temperature Dependence of Isotope Ratios in Tree Rings

    PubMed Central

    Libby, L. M.; Pandolfi, L. J.

    1974-01-01

    The stable isotope ratios of carbon, oxygen, and hydrogen have been measured for a German oak in wood samples of roughly three years each, for the years 1712-1954 A.D., and correlated with the existing weather records from England, Basel, and Geneva to evaluate the empirical temperature coefficients. Isotope ratios in a second official oak, measured for the years 1530-1800 A.D., show the cold temperatures of the Little Ice Age interspersed with warm intervals. PMID:16592163

  12. Oxygen isotope ratios in eclogites from kimberlites.

    PubMed

    Garlick, G D; Macgregor, I D; Vogel, D E

    1971-06-04

    The oxygen isotope compositions (delta(18)O) of eclogitic xenoliths from the Roberts Victor kimberlite range from 2 to 8 per mil relative to SMOW (standard mean ocean water). This surprising variation appears to be due to fractional crystallization: the eclogites rich in oxygen-18 represent early crystal accumulates; the eclogites poor in oxygen-18 represent residual liquids. Crystal-melt partitioning probably exceeded 3 per mil and is interpreted to be pressure-dependent. Anomalous enrichment of oxygen-18 in cumulate eclogites relative to ultramafic xenoliths suggests that crystal-melt partitioning increased after melt-formation but prior to crystallization.

  13. Plutonium isotope ratio variations in North America

    SciTech Connect

    Steiner, Robert E; La Mont, Stephen P; Eisele, William F; Fresquez, Philip R; Mc Naughton, Michael; Whicker, Jeffrey J

    2010-12-14

    Historically, approximately 12,000 TBq of plutonium was distributed throughout the global biosphere by thermo nuclear weapons testing. The resultant global plutonium fallout is a complex mixture whose {sup 240}Pu/{sup 239}Pu atom ratio is a function of the design and yield of the devices tested. The average {sup 240}Pu/{sup 239}Pu atom ratio in global fallout is 0.176 + 014. However, the {sup 240}Pu/{sup 239}Pu atom ratio at any location may differ significantly from 0.176. Plutonium has also been released by discharges and accidents associated with the commercial and weapons related nuclear industries. At many locations contributions from this plutonium significantly alters the {sup 240}Pu/{sup 239}Pu atom ratios from those observed in global fallout. We have measured the {sup 240}Pu/{sup 239}Pu atom ratios in environmental samples collected from many locations in North America. This presentation will summarize the analytical results from these measurements. Special emphasis will be placed on interpretation of the significance of the {sup 240}Pu/{sup 239}Pu atom ratios measured in environmental samples collected in the Arctic and in the western portions of the United States.

  14. Advances in laser-based isotope ratio measurements: selected applications

    NASA Astrophysics Data System (ADS)

    Kerstel, E.; Gianfrani, L.

    2008-09-01

    Small molecules exhibit characteristic ro-vibrational transitions in the near- and mid-infrared spectral regions, which are strongly influenced by isotopic substitution. This gift of nature has made it possible to use laser spectroscopy for the accurate analysis of the isotopic composition of gaseous samples. Nowadays, laser spectroscopy is clearly recognized as a valid alternative to isotope ratio mass spectrometry. Laser-based instruments are leaving the research laboratory stage and are being used by a growing number of isotope researchers for significant advances in their own field of research. In this review article, we discuss the current status and new frontiers of research on high-sensitivity and high-precision laser spectroscopy for isotope ratio analyses. Although many of our comments will be generally applicable to laser isotope ratio analyses in molecules of environmental importance, this paper concerns itself primarily with water and carbon dioxide, two molecules that were studied extensively in our respective laboratories. A complete coverage of the field is practically not feasible in the space constraints of this issue, and in any case doomed to fail, considering the large body of work that has appeared ever since the review by Kerstel in 2004 ( Handbook of Stable Isotope Analytical Techniques, Chapt. 34, pp. 759-787).

  15. LITERATURE SURVEY ON ISOTOPIC ABUNDANCE RATIO MEASUREMENTS - 2001-2005

    SciTech Connect

    HOLDEN, N.E.

    2005-08-13

    Along with my usual weekly review of the published literature for new nuclear data, I also search for new candidates for best measurements of isotopic abundances from a single source. Most of the published articles, that I previously had found in the Research Library at the Brookhaven Lab, have already been sent to the members of the Atomic Weights Commission, by either Michael Berglund or Thomas Walczyk. In the last few days, I checked the published literature for any other articles in the areas of natural variations in isotopic abundance ratios, measurements of isotopic abundance ratios on samples of extra-terrestrial material and isotopic abundance ratio measurements performed using ICPMS instruments. Hopefully this information will be of interest to members of the Commission, the sub-committee on isotopic abundance measurements (SIAM), members of the former sub-committee on natural isotopic fractionation (SNIF), the sub-committee on extra-terrestrial isotope ratios (SETIR), the RTCE Task Group and the Guidelines Task Group, who are dealing with ICPMS and TIMS comparisons. In the following report, I categorize the publications in one of four areas. Measurements performed using either positive or negative ions with Thermal Ionization Mass Spectrometer, TIMS, instruments; measurements performed on Inductively Coupled Plasma Mass Spectrometer, ICPMS, instruments; measurements of natural variations of the isotopic abundance ratios; and finally measurements on extra-terrestrial samples with instrumentation of either type. There is overlap in these areas. I selected out variations and ET results first and then categorized the rest of the papers by TIMS and ICPMS.

  16. Understanding radioxenon isotopical ratios originating from radiopharmaceutical facilities

    NASA Astrophysics Data System (ADS)

    Saey, P. R. J.; Ringbom, A.; Bowyer, T. W.; Becker, A.; de Geer, L.-E.; Nikkinen, M.; Payne, R. F.

    2009-04-01

    It was recently shown that radiopharmaceutical facilities (RPF) are major contributors to the general background of 133Xe and other xenon isotopes both in the northern and southern hemisphere. To distinguish a nuclear explosion signal from releases from civil nuclear facilities, not only the activity concentrations but also the ratios of the four different CTBT relevant radioxenon isotopes (131mXe, 133mXe, 133Xe and 135Xe) have to be well understood. First measurements taken recently in and around two of the world's largest RPF's: NTP at Pelindaba, South Africa and IRE at Fleurus, Belgium have been presented. At both sites, also stack samples were taken in close cooperation with the facility operators. The radioxenon in Belgium could be classified in four classes: the normal European background (133Xe activity between 0 - 5 mBq/m3) on one hand and then the samples where all four isotopes were detected with 133mXe/131mXe > 1. In northern South Africa the Pelindaba RPF is in practice the sole source of radioxenon. It generated a background of 133Xe at the measurement site some 230 km to the west of the RPF of 0 - 5 mBq/m3. In the cases where the air from the Pelindaba facility reached the measurement site directly and in a short time period, the 133Xe was higher, also 135Xe was present and in some samples 133mXe as well. The ratios of the activity concentrations of 135Xe/133Xe vs. 133mXe/131mXe (Multiple Isotope Ratio Plot - MIRC) have been analysed. For both facilities, the possible theoretical ratio's for different scenarios were calculated with the information available and compared with the measurements. It was found that there is an excess of 131mXe present in the European samples compared to theoretical calculations. A similar excess has also been seen in samples measured in northern America. In South Africa, neither the environmental samples nor the stack ones contained 131mXe at measurable levels. This can probably be explained by different processes and

  17. Stable Isotope Ratios as Biomarkers of Diet for Health Research.

    PubMed

    O'Brien, Diane M

    2015-01-01

    Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment. Consequently, there is a pressing need for more objective biomarkers of diet for use in health research. The stable isotope ratios of light elements are a promising set of candidate biomarkers because they vary naturally and reproducibly among foods, and those variations are captured in molecules and tissues with high fidelity. Recent studies have identified valid isotopic measures of short- and long-term sugar intake, meat intake, and fish intake in specific populations. These studies provide a strong foundation for validating stable isotopic biomarkers in the general US population. Approaches to improve specificity for specific foods are needed; for example, by modeling intake using multiple stable isotope ratios or by isolating and measuring specific molecules linked to foods of interest.

  18. Stable Isotope Ratios as Biomarkers of Diet for Health Research

    PubMed Central

    O’Brien, Diane M.

    2016-01-01

    Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment. Consequently there is a pressing need for more objective biomarkers of diet for use in health research. The stable isotope ratios of light elements are a promising set of candidate biomarkers because they vary naturally and reproducibly among foods, and those variations are captured in molecules and tissues with high fidelity. Recent studies have identified valid isotopic measures of short and long-term sugar intake, meat intake, and fish intake in specific populations. These studies provide a strong foundation for validating stable isotopic biomarkers in the general United States population. Approaches to improve specificity for specific foods are needed, for example, by modeling intake using multiple stable isotope ratios, or by isolating and measuring specific molecules linked to foods of interest. PMID:26048703

  19. Stable Isotope Ratios and the Forensic Analysis of Microorganisms

    SciTech Connect

    Kreuzer-Martin, Helen W.; Jarman, Kristin H.

    2007-06-01

    In the aftermath of the anthrax letters of 2001, researchers have been exploring various analytical signatures for the purpose of characterizing the production environment of microorganisms. One such signature is stable isotope ratios, which in heterotrophs are a function of nutrient and water sources. Here we discuss the use of stable isotope ratios in microbe forensics, using as a database the carbon, nitrogen, oxygen and hydrogen stable isotope ratios of 247 separate cultures of B. subtilis 6051 spores produced on a total of 32 different culture media. In the context of using stable isotope ratios as a signature for sample matching, we present an analysis of variation between individual samples, between cultures produced in tandem, and between cultures produced in the same medium but at different times. Additionally, we correlate the stable isotope ratios of carbon, nitrogen, oxygen, and hydrogen for growth medium nutrients or water with those of spores and show examples of how these relationships can be used to exclude nutrient or water samples as possible growth substrates for specific cultures.

  20. Isotope Ratio Monitoring Gas Chromatography Mass Spectrometry (IRM-GCMS)

    NASA Technical Reports Server (NTRS)

    Freeman, K. H.; Ricci, S. A.; Studley, A.; Hayes, J. M.

    1989-01-01

    On Earth, the C-13 content of organic compounds is depleted by roughly 13 to 23 permil from atmospheric carbon dioxide. This difference is largely due to isotope effects associated with the fixation of inorganic carbon by photosynthetic organisms. If life once existed on Mars, then it is reasonable to expect to observe a similar fractionation. Although the strongly oxidizing conditions on the surface of Mars make preservation of ancient organic material unlikely, carbon-isotope evidence for the existence of life on Mars may still be preserved. Carbon depleted in C-13 could be preserved either in organic compounds within buried sediments, or in carbonate minerals produced by the oxidation of organic material. A technique is introduced for rapid and precise measurement of the C-13 contents of individual organic compounds. A gas chromatograph is coupled to an isotope-ratio mass spectrometer through a combustion interface, enabling on-line isotopic analysis of isolated compounds. The isotope ratios are determined by integration of ion currents over the course of each chromatographic peak. Software incorporates automatic peak determination, corrections for background, and deconvolution of overlapped peaks. Overall performance of the instrument was evaluated by the analysis of a mixture of high purity n-alkanes of know isotopic composition. Isotopic values measured via IRM-GCMS averaged withing 0.55 permil of their conventionally measured values.

  1. High Resolution Double-Focusing Isotope Ratio Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Radke, J.; Deerberg, M.; Hilkert, A.; Schlüter, H.-J.; Schwieters, J.

    2012-04-01

    In recent years isotope ratio mass spectrometry has extended to the capability of quantifying very small isotope signatures related with low abundances and simultaneously detecting molecular masses such as isotopomers and isotopologues containing clumped isotopes. Some of those applications are limited by molecular interferences like different gas molecules with the same nominal mass, e.g. Ar/O2, adducts of the same molecule or of different molecules, and very small isotope abundances. The Thermo Scientific MAT 253 ULTRA is the next generation of high precision gas isotope ratio mass spectrometry, which combines a 10 KV gas ionization source (Thermo Scientific MAT 253) with a double focusing multi-collector mass analyzer (Thermo Scientific Neptune) and reduces those limitations by measuring isotope ratios on a larger dynamic range with high precision. Small ion beam requirements and high sensitivity are achieved by signal-to-noise improvements through enhanced ion beam amplification in faraday cups and ion counters. Interfering backgrounds, e.g. interfering isotopologues or isobaric ions of contaminants, are dramatically decreased by a dynamic range increase combined with high evacuation leading to undisturbed ion transmission through the double-focusing analyser. Furthermore, automated gain calibration for mathematical baseline corrections, switchable detector arrays, ion source control, analyser focusing and full data export is controlled under Isodat data control. New reference/sample strategies are under investigation besides incorporation of the continuous-flow technique and its versatile inlet devices. We are presenting first results and applications of the MAT 253 Ultra.

  2. Nitrogen isotopic analyses by isotope-ratio-monitoring gas chromatography/mass spectrometry

    NASA Technical Reports Server (NTRS)

    Merritt, D. A.; Hayes, J. M.

    1994-01-01

    Amino acids containing natural-abundance levels of 15N were derivatized and analyzed isotopically using a technique in which individual compounds are separated by gas chromatography, combusted on-line, and the product stream sent directly to an isotope-ratio mass spectrometer. For samples of N2 gas, standard deviations of ratio measurement were better than 0.1% (Units for delta are parts per thousand or per million (%).) for samples larger than 400 pmol and better than 0.5% for samples larger than 25 pmol (0.1% 15N is equivalent to 0.00004 atom % 15N). Results duplicated those of conventional, batchwise analyses to within 0.05%. For combustion of organic compounds yielding CO2/N2 ratios between 14 and 28, in particular for N-acetyl n-propyl derivatives of amino acids, delta values were within 0.25% of results obtained using conventional techniques and standard deviations were better than 0.35%. Pooled data for measurements of all amino acids produced an accuracy and precision of 0.04 and 0.23%, respectively, when 2 nmol of each amino acid was injected on column and 20% of the stream of combustion products was delivered to the mass spectrometer.

  3. Radioactive halos and ion microprobe measurement of Pb isotope ratios

    NASA Technical Reports Server (NTRS)

    Gentry, R. V.

    1974-01-01

    This investigation was to obtain, if possible, the Pb isotope ratios of both lunar and meteoritic troilite grains by utilizing ion microprobe techniques. Such direct in situ measurement of Pb isotope ratios would eliminate contamination problems inherent in wet chemistry separation procedures, and conceivably determine whether lunar troilite grains were of meteoritic origin. For comparison purposes two samples of meteoritic troilite were selected (one from Canyon Diablo) for analysis along with two very small lunar troilite grains (approximately 50-100 microns). It was concluded that the ion microprobe as presently operating, does not permit the in situ measurement of Pb isotope ratios in lunar or meteoritic troilite. On the basis of these experiments no conclusions could be drawn as to the origin of the lunar troilite grains.

  4. Thermohaline Mixing and Isotopic Ratios in AGB Stars

    NASA Astrophysics Data System (ADS)

    Stancliffe, R. J.

    2015-08-01

    I investigate the effects of thermohaline mixing on the isotopic ratios of asymptotic giant branch (AGB) stars. While thermohaline mixing has been shown to be an effective means of changing the surface composition of low-mass stars while they ascend the upper part of the giant branch, the effect of this mechanism on the AGB is almost negligible. The carbon isotopic ratio is barely affected during the earliest pulses, and as the 12C content increases due to third dredge-up this effect becomes seriously curtailed. This is because structural changes affect the relative locations of 3He-burning and the CNO cycle. While the isotopic ratios are barely affected by thermohaline mixing on the AGB, there is a substantial increase in the surface lithium abundance due to the action of this mechanism.

  5. Using isotopic ratios for discrimination of environmental anthropogenic radioactivity.

    PubMed

    Hayes, Robert B; Akbarzadeh, Mansour

    2014-10-01

    When air is pulled into the WIPP repository for ventilation purposes, this air is unfiltered and contains all the components of ubiquitous anthropogenic radionuclides from global nuclear fallout (including Cs and Pu isotopes). Although the NORM in aeolian sand and dust contribute to the gross alpha beta activity on effluent air filters, there remains a need to discriminate effluent TRU generated in the disposal process at WIPP from TRU being pulled into the repository with the unfiltered surface air. This is only evaluated using ratios of Cs and Pu activity found through radioassay of air filters taken from the mine effluent. By characterizing both the credible range of Cs/Pu ratios from the environment and those known to exist in the waste, a rigorous test criteria is attained. The use of HPGE to assay Cs in the intake dust plated out in the mine allowed a gross assay of total TRU radioactivity pulled into the mine over time from global fallout. Radiochemistry of samples from deposition in the mine's air intake shaft was also carried out. The use of net activity ratios at background levels is also shown to follow a Cauchy distribution in terms of their expected statistical distributions.

  6. Detection of adulterated honey produced by honeybee (Apis mellifera L.) colonies fed with different levels of commercial industrial sugar (C₃ and C₄ plants) syrups by the carbon isotope ratio analysis.

    PubMed

    Guler, Ahmet; Kocaokutgen, Hasan; Garipoglu, Ali V; Onder, Hasan; Ekinci, Deniz; Biyik, Selim

    2014-07-15

    In the present study, one hundred pure and adulterated honey samples obtained from feeding honeybee colonies with different levels (5, 20 and 100 L/colony) of various commercial sugar syrups including High Fructose Corn Syrup 85 (HFCS-85), High Fructose Corn Syrup 55 (HFCS-55), Bee Feeding Syrup (BFS), Glucose Monohydrate Sugar (GMS) and Sucrose Sugar (SS) were evaluated in terms of the δ(13)C value of honey and its protein, difference between the δ(13)C value of protein and honey (Δδ(13)C), and C4% sugar ratio. Sugar type, sugar level and the sugar type*sugar level interaction were found to be significant (P<0.001) regarding the evaluated characteristics. Adulterations could not be detected in the 5L/colony syrup level of all sugar types when the δ(13)C value of honey, Δδ(13)C (protein-honey), and C4% sugar ratio were used as criteria according to the AOAC standards. However, it was possible to detect the adulteration by using the same criteria in the honeys taken from the 20 and 100 L/colony of HFCS-85 and the 100L/colony of HFCS-55. Adulteration at low syrup level (20 L/colony) was more easily detected when the fructose content of HFCS syrup increased. As a result, the official methods (AOAC, 978.17, 1995; AOAC, 991.41, 1995; AOAC 998.12, 2005) and Internal Standard Carbon Isotope Ratio Analysis could not efficiently detect the indirect adulteration of honey obtained by feeding the bee colonies with the syrups produced from C3 plants such as sugar beet (Beta vulgaris) and wheat (Triticium vulgare). For this reason, it is strongly needed to develop novel methods and standards that can detect the presence and the level of indirect adulterations.

  7. Seawater calcium isotopic ratios across the Eocene-Oligocene Transition

    NASA Astrophysics Data System (ADS)

    Griffith, E. M.; Paytan, A.

    2009-12-01

    We reconstructed the evolution of the seawater calcium (Ca) isotopic ratio from marine (pelagic) barite and bulk calcium carbonate over the Eocene-Oligocene Transition (EOT), a period of extreme and rapid change in the global calcite compensation depth (CCD) (Lyle et al., 2008). The CCD is controlled by the balance between calcium carbonate deposition and dissolution in deep sea sediments. Large fluctuations in the CCD may cause changes in the concentration of dissolved Ca in seawater and its isotopic composition if accompanied by imbalances in marine Ca sources and sinks (De La Rocha and DePaolo, 2000). Our results show that the permanent deepening of the CCD during the EOT, which coincided with the major Cenozoic glaciation around 34 million years ago (Zachos et al., 2001), was not accompanied by a significant long-term change in the isotopic ratio of Ca in seawater or its sink (calcium carbonate). A simple isotopic mass balance model is constructed to compare predicted and observed isotopic fluctuations. References: Lyle, M. et al. Pacific Ocean and Cenozoic evolution of climate. Rev. Geophys. 46, 1-47 (2008). De La Rocha, C. L. & DePaolo, D. J. Isotopic evidence for variations in the marine calcium cycle over the Cenozoic. Science 289, 1176-1178 (2000). Zachos, J., Pagani, M., Sloan, L., Thomas, E. & Billups, K. Trends, rhythms, and aberrations in global climate 65 ma to present. Science 292, 686-693 (2001).

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

    PubMed

    Tanimizu, Masaharu; Sohrin, Yoshiki; Hirata, Takafumi

    2013-03-01

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

  9. The use of carbon stable isotope ratios in drugs characterization

    SciTech Connect

    Magdas, D. A. Cristea, G. Bot, A. Mirel, V.

    2013-11-13

    Isotopic Ratio Mass Spectrometry (IRMS) is an effective toll to be used for drug product authentication. The isotopic composition could be used to assist in the differentiation between batches of drugs and assist in the identification of counterfeit materials on the market. Only two factors affect the isotopic ratios in pharmaceutical components: the isotopic composition of the raw materials and the synthetic processes performed upon them. Counterfeiting of pharmaceutical drugs threatens consumer confidence in drug products companies' economical well-being. In this preliminary study, the analyzed samples consist in two types of commercially available analgesics, which were purchases from Romanian pharmacies. Differences in δ{sup 13}C between batches from −29.7 to −31.6% were observed, demonstrating that this method can be used to differentiate among individual drug batches and subsequently identify counterfeits on the market. On the other hand, carbon isotopic ratios differences among producers were recorded, the variations being between −31.3 to −34.9% for the same type of analgesic, but from different manufactures.

  10. The use of carbon stable isotope ratios in drugs characterization

    NASA Astrophysics Data System (ADS)

    Magdas, D. A.; Cristea, G.; Bot, A.; Mirel, V.

    2013-11-01

    Isotopic Ratio Mass Spectrometry (IRMS) is an effective toll to be used for drug product authentication. The isotopic composition could be used to assist in the differentiation between batches of drugs and assist in the identification of counterfeit materials on the market. Only two factors affect the isotopic ratios in pharmaceutical components: the isotopic composition of the raw materials and the synthetic processes performed upon them. Counterfeiting of pharmaceutical drugs threatens consumer confidence in drug products companies' economical well-being. In this preliminary study, the analyzed samples consist in two types of commercially available analgesics, which were purchases from Romanian pharmacies. Differences in δ13C between batches from -29.7 to -31.6% were observed, demonstrating that this method can be used to differentiate among individual drug batches and subsequently identify counterfeits on the market. On the other hand, carbon isotopic ratios differences among producers were recorded, the variations being between -31.3 to -34.9% for the same type of analgesic, but from different manufactures.

  11. Stable isotope ratio method for the characterisation of the poultry house environment.

    PubMed

    Skipitytė, Raminta; Mašalaitė, Agnė; Garbaras, Andrius; Mickienė, Rūta; Ragažinskienė, Ona; Baliukonienė, Violeta; Bakutis, Bronius; Šiugždaitė, Jūratė; Petkevičius, Saulius; Maruška, Audrius Sigitas; Remeikis, Vidmantas

    2017-06-01

    Stable isotope analysis was applied to describe the poultry house environment. The poultry house indoor environment was selected for this study due to the relevant health problems in animals and their caretakers. Air quality parameters including temperature, relative humidity, airflow rate, NH3, CO2 and total suspended particles, as well as mean levels of total airborne bacteria and fungi count, were measured. Carbon isotope ratios ((13)C/(12)C) were obtained in size-segregated aerosol particles. The carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) isotope ratios were measured in feed, litter, scrapings from the ventilation system, feathers and eggs. Additionally, the distribution of δ(13)C and δ(15)N values in different tissues of the chicken was examined. The airborne bacteria and fungi extracted from the air filters collected from poultry farms were grown in the laboratory in media with known isotope values and measured for stable isotope ratios. Analysis of isotope fractionation between microorganisms and their media indicated the applicability of stable isotope analysis in bulk samples for the identification of source material. The analysed examples imply that stable isotope analysis can be used to examine the indoor environment along with its biology and ecology, and serve as an informative bioanalytical tool.

  12. Isotope Ratios Reveal Trickery in the Produce Aisle

    ERIC Educational Resources Information Center

    Journal of Chemical Education, 2007

    2007-01-01

    A new technique for the proper checking and banning of organic food items is proposed. The analysis of the nitrogen isotope ratio present in the food is found to be a perfect standard for the organic checking of the food products.

  13. Uranium Isotope Ratios in Modern and Precambrian Soils

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  14. Stable isotope ratios in hair and teeth reflect biologic rhythms.

    PubMed

    Appenzeller, Otto; Qualls, Clifford; Barbic, Franca; Furlan, Raffaello; Porta, Alberto

    2007-07-25

    Biologic rhythms give insight into normal physiology and disease. They can be used as biomarkers for neuronal degenerations. We present a diverse data set to show that hair and teeth contain an extended record of biologic rhythms, and that analysis of these tissues could yield signals of neurodegenerations. We examined hair from mummified humans from South America, extinct mammals and modern animals and people, both healthy and diseased, and teeth of hominins. We also monitored heart-rate variability, a measure of a biologic rhythm, in some living subjects and analyzed it using power spectra. The samples were examined to determine variations in stable isotope ratios along the length of the hair and across growth-lines of the enamel in teeth. We found recurring circa-annual periods of slow and fast rhythms in hydrogen isotope ratios in hair and carbon and oxygen isotope ratios in teeth. The power spectra contained slow and fast frequency power, matching, in terms of normalized frequency, the spectra of heart rate variability found in our living subjects. Analysis of the power spectra of hydrogen isotope ratios in hair from a patient with neurodegeneration revealed the same spectral features seen in the patient's heart-rate variability. Our study shows that spectral analysis of stable isotope ratios in readily available tissues such as hair could become a powerful diagnostic tool when effective treatments and neuroprotective drugs for neurodegenerative diseases become available. It also suggests that similar analyses of archaeological specimens could give insight into the physiology of ancient people and animals.

  15. Seawater calcium isotope ratios across the Eocene-Oligocene transition

    USGS Publications Warehouse

    Griffith, E.M.; Paytan, A.; Eisenhauer, A.; Bullen, T.D.; Thomas, E.

    2011-01-01

    During the Eocene-Oligocene transition (EOT, ca. 34 Ma), Earth's climate cooled significantly from a greenhouse to an icehouse climate, while the calcite (CaCO3) compensation depth (CCD) in the Pacific Ocean increased rapidly. Fluctuations in the CCD could result from various processes that create an imbalance between calcium (Ca) sources to, and sinks from, the ocean (e.g., weathering and CaCO3 deposition), with different effects on the isotopic composition of dissolved Ca in the oceans due to differences in the Ca isotopic composition of various inputs and outputs. We used Ca isotope ratios (??44/40Ca) of coeval pelagic marine barite and bulk carbonate to evaluate changes in the marine Ca cycle across the EOT. We show that the permanent deepening of the CCD was not accompanied by a pronounced change in seawater ??44/40Ca, whereas time intervals in the Neogene with smaller carbonate depositional changes are characterized by seawater ??44/40Ca shifts. This suggests that the response of seawater ??44/40Ca to changes in weathering fluxes and to imbalances in the oceanic alkalinity budget depends on the chemical composition of seawater. A minor and transient fluctuation in the Ca isotope ratio of bulk carbonate may reflect a change in isotopic fractionation associated with CaCO3 precipitation from seawater due to a combination of factors, including changes in temperature and/or in the assemblages of calcifying organisms. ?? 2011 Geological Society of America.

  16. Finite mixture models for the computation of isotope ratios in mixed isotopic samples

    NASA Astrophysics Data System (ADS)

    Koffler, Daniel; Laaha, Gregor; Leisch, Friedrich; Kappel, Stefanie; Prohaska, Thomas

    2013-04-01

    Finite mixture models have been used for more than 100 years, but have seen a real boost in popularity over the last two decades due to the tremendous increase in available computing power. The areas of application of mixture models range from biology and medicine to physics, economics and marketing. These models can be applied to data where observations originate from various groups and where group affiliations are not known, as is the case for multiple isotope ratios present in mixed isotopic samples. Recently, the potential of finite mixture models for the computation of 235U/238U isotope ratios from transient signals measured in individual (sub-)µm-sized particles by laser ablation - multi-collector - inductively coupled plasma mass spectrometry (LA-MC-ICPMS) was demonstrated by Kappel et al. [1]. The particles, which were deposited on the same substrate, were certified with respect to their isotopic compositions. Here, we focus on the statistical model and its application to isotope data in ecogeochemistry. Commonly applied evaluation approaches for mixed isotopic samples are time-consuming and are dependent on the judgement of the analyst. Thus, isotopic compositions may be overlooked due to the presence of more dominant constituents. Evaluation using finite mixture models can be accomplished unsupervised and automatically. The models try to fit several linear models (regression lines) to subgroups of data taking the respective slope as estimation for the isotope ratio. The finite mixture models are parameterised by: • The number of different ratios. • Number of points belonging to each ratio-group. • The ratios (i.e. slopes) of each group. Fitting of the parameters is done by maximising the log-likelihood function using an iterative expectation-maximisation (EM) algorithm. In each iteration step, groups of size smaller than a control parameter are dropped; thereby the number of different ratios is determined. The analyst only influences some control

  17. High Precision Low-blank Lithium Isotope Ratios in Forams.

    NASA Astrophysics Data System (ADS)

    Misra, S.; Froelich, P. N.

    2007-12-01

    We present a high precision (±1‰, 2σ) low blank (<500 fg/ml) method for Li isotope measurements of forams using <2 ng of Li by single collector Quad ICP-MS (Agilent 7500cs). The Li isotope ratio of seawater (δ7Li) recorded in planktonic forams has the potential to constrain the evolution of seawater chemistry and elucidate the factors driving variations of oceanic mass balances linked to the continental and sea floor/hydrothermal silica cycles. In addition a δ7Li record of seawater will complement other long-term recorders of seawater chemistry such as Sr, Os and S isotopes. Li isotope measurements of forams are limited by several factors: low Li concentrations in forams (1-2 ppm), instrument-induced fractionation and mass bias effects, matrix effects, high Li blanks and incomplete recovery of Li during column separation. Modest concentrations of alkali and alkaline earth elements in the matrix result in variable mass bias in measured Li isotope ratios. Even worse, Li strongly fractionates during chromatographic clean-up to remove Na+, Ca2+ and Mg2+, from +100‰ in the leading edge to - 100‰ in the trailing edge of elution peaks (Urey 1938). Consequently, miniscule incomplete recoveries of Li during chromatographic separations can result in large unrecognized isotope fractionation of eluents. Large mass-dependent fractionation caused by a difference of 17% in mass between 6Li and 7Li, makes Li a powerful tracer of geochemical processes, but also promotes large and difficult-to-fix isotope fractionations during laboratory chemical processing. Matrix effects of Na & Ca and of column chromatography on Li isotope ratios were investigated using artificial Li solutions representative of foram compositions (matrix matching). Li/Ca and Li/Na ratios in cleaned forams are 10 μmol/mol and 3 mmol/mol respectively. An ICP-MS tolerance limit of 20 ppb for Na and 20 μM for Ca was established, much higher tolerances than by TIMS. A single step chromatographic method to

  18. Oxygen isotopic ratios in intermediate-mass red giants

    NASA Astrophysics Data System (ADS)

    Lebzelter, T.; Straniero, O.; Hinkle, K. H.; Nowotny, W.; Aringer, B.

    2015-06-01

    Context. The abundances of the three main isotopes of oxygen are altered in the course of the CNO-cycle. When the first dredge-up mixes the burning products to the surface, the nucleosynthesis processes can be probed by measuring oxygen isotopic ratios. Aims: By measuring 16O/17O and 16O/18O in red giants of known mass we compare the isotope ratios with predictions from stellar and galactic evolution modelling. Methods: Oxygen isotopic ratios were derived from the K-band spectra of six red giants. The sample red giants are open cluster members with known masses of between 1.8 and 4.5 M⊙. The abundance determination employs synthetic spectra calculated with the COMARCS code. The effect of uncertainties in the nuclear reaction rates, the mixing length, and of a change in the initial abundance of the oxygen isotopes was determined by a set of nucleosynthesis and mixing models using the FUNS code. Results: The observed 16O/17O ratios are in good agreement with the model results, even if the measured values do not present clear evidence of a variation with the stellar mass. The observed 16O/18O ratios are clearly lower than the predictions from our reference model. Variations in nuclear reaction rates and mixing length parameter both have only a very weak effect on the predicted values. The 12C/13C ratios of the K giants studied implies the absence of extra-mixing in these objects. Conclusions: A comparison with galactic chemical evolution models indicates that the 16O/18O abundance ratio underwent a faster decrease than predicted. To explain the observed ratios, the most likely scenario is a higher initial 18O abundance combined with a lower initial 16O abundance. Comparing the measured 18O/17O ratio with the corresponding value for the interstellar medium points towards an initial enhancement of 17O as well. Limitations imposed by the observations prevent this from being a conclusive result.

  19. Lignin methoxyl hydrogen isotope ratios in a coastal ecosystem

    NASA Astrophysics Data System (ADS)

    Feakins, Sarah J.; Ellsworth, Patricia V.; Sternberg, Leonel da Silveira Lobo

    2013-11-01

    Stable hydrogen isotope ratios of plant lignin methoxyl groups have recently been shown to record the hydrogen isotopic composition of meteoric water. Here we extend this technique towards tracing water source variations across a saltwater to freshwater gradient in a coastal, subtropical forest ecosystem. We measure the hydrogen isotopic composition of xylem water (δDxw) and methoxyl hydrogen (δDmethoxyl) to calculate fractionations for coastal mangrove, buttonwood and hammock tree species in Sugarloaf Key, as well as buttonwoods from Miami, both in Florida, USA. Prior studies of the isotopic composition of cellulose and plant leaf waxes in coastal ecosystems have yielded only a weak correlation to source waters, attributed to leaf water effects. Here we find δDmethoxyl values range from -230‰ to -130‰, across a 40‰ range in δDxw with a regression equation of δDmethoxyl ‰ = 1.8 * δDxw - 178‰ (R2 = 0.48, p < 0.0001, n = 74). This is comparable within error to the earlier published relationship for terrestrial trees which was defined across a much larger 125‰ isotopic range in precipitation. Analytical precision for measurements of δD values of pure CH3I by gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-P-IRMS) is σ = 6‰ (n = 31), which is considerably better than for CH3I liberated through cleavage with HI from lignin with σ = 18‰ (n = 26). Our results establish that δDmethoxyl can record water sources and salinity incursion in coastal ecosystems, where variations sufficiently exceed method uncertainties (i.e., applications with δD excursions >50‰). For the first time, we also report yields of propyl iodide, which may indicate lignin synthesis of propoxyl groups under salt-stress.

  20. MAGNESIUM ISOTOPE RATIOS IN {omega} CENTAURI RED GIANTS

    SciTech Connect

    Da Costa, G. S.; Norris, John E.; Yong, David

    2013-05-20

    We have used the high-resolution observations obtained at the Anglo-Australian Telescope with Ultra-High Resolution Facility (R {approx} 100,000) and at Gemini-S with b-HROS (R {approx} 150,000) to determine magnesium isotope ratios for seven {omega} Cen red giants that cover a range in iron abundance from [Fe/H] = -1.78 to -0.78 dex, and for two red giants in M4 (NGC 6121). The {omega} Cen stars sample both the ''primordial'' (i.e., O-rich, Na- and Al-poor) and the ''extreme'' (O-depleted, Na- and Al-rich) populations in the cluster. The primordial population stars in both {omega} Cen and M4 show ({sup 25}Mg, {sup 26}Mg)/{sup 24}Mg isotopic ratios that are consistent with those found for the primordial population in other globular clusters with similar [Fe/H] values. The isotopic ratios for the {omega} Cen extreme stars are also consistent with those for extreme population stars in other clusters. The results for the extreme population stars studied indicate that the {sup 26}Mg/{sup 24}Mg ratio is highest at intermediate metallicities ([Fe/H] < -1.4 dex), and for the highest [Al/Fe] values. Further, the relative abundance of {sup 26}Mg in the extreme population stars is notably higher than that of {sup 25}Mg, in contrast to model predictions. The {sup 25}Mg/{sup 24}Mg isotopic ratio in fact does not show any obvious dependence on either [Fe/H] or [Al/Fe] nor, intriguingly, any obvious difference between the primordial and extreme population stars.

  1. ISOTOPIC RATIOS IN TITAN's METHANE: MEASUREMENTS AND MODELING

    SciTech Connect

    Nixon, C. A.; Achterberg, R. K.; Temelso, B.; Vinatier, S.; Bezard, B.; Coustenis, A.; Teanby, N. A.; Mandt, K. E.; Sherrill, C. D.; Irwin, P. G. J.; Jennings, D. E.; Romani, P. N.; Flasar, F. M.

    2012-04-20

    The existence of methane in Titan's atmosphere ({approx}6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of {approx}20 Myr. In this paper, we examine the clues available from isotopic ratios ({sup 12}C/{sup 13}C and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH{sub 4} collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: {sup 13}CH{sub 4}, {sup 12}CH{sub 3}D, and {sup 13}CH{sub 3}D. From these we compute estimates of {sup 12}C/{sup 13}C = 86.5 {+-} 8.2 and D/H = (1.59 {+-} 0.33) Multiplication-Sign 10{sup -4}, in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH{sub 4} + C{sub 2}H {yields} CH{sub 3} + C{sub 2}H{sub 2}. Using these new measurements and predictions we proceed to model the time evolution of {sup 12}C/{sup 13}C and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model 1 (no resupply of CH{sub 4}), we find that the present-day {sup 12}C/{sup 13}C implies that the CH{sub 4} entered the atmosphere 60-1600 Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently-most likely less than 10 Myr ago-if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing. We conclude by discussing how these findings may be combined with other evidence to constrain the overall history of the atmospheric

  2. Isotopic Ratios in Titan's Methane: Measurements and Modeling

    NASA Technical Reports Server (NTRS)

    Nixon, C. A.; Temelso, B.; Vinatier, S.; Teanby, N. A.; Bezard, B.; Achterberg, R. K.; Mandt, K. E.; Sherrill, C. D.; Irwin, P. G.; Jennings, D. E.; Romani, P. N.; Coustenis, A.; Flasar, F. M.

    2012-01-01

    The existence of methane in Titan's atmosphere (approx. 6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of approx 20 Myr. In this paper, we examine the clues available from isotopic ratios (C-12/C-13 and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH4 collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: (13)CH4, (12)CH3D, and (13)CH3D. From these we compute estimates of C-12/C-13 = 86.5 +/- 8.2 and D/H = (1.59 +/- 0.33) x 10(exp -4) , in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH4 + C2H yields CH3 + C2H2. Using these new measurements and predictions we proceed to model the time evolution of C-12/C-13 and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model 1 (no resupply of CH4), we find that the present-day C-12/C-13 implies that the CH4 entered the atmosphere 60-1600 Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently-most likely less than 10 Myr ago-if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing, We conclude by discussing how these findings may be combined with other evidence to constrain the overall history of the atmospheric methane.

  3. Accurate and precise zinc isotope ratio measurements in urban aerosols.

    PubMed

    Gioia, Simone; Weiss, Dominik; Coles, Barry; Arnold, Tim; Babinski, Marly

    2008-12-15

    We developed an analytical method and constrained procedural boundary conditions that enable accurate and precise Zn isotope ratio measurements in urban aerosols. We also demonstrate the potential of this new isotope system for air pollutant source tracing. The procedural blank is around 5 ng and significantly lower than published methods due to a tailored ion chromatographic separation. Accurate mass bias correction using external correction with Cu is limited to Zn sample content of approximately 50 ng due to the combined effect of blank contribution of Cu and Zn from the ion exchange procedure and the need to maintain a Cu/Zn ratio of approximately 1. Mass bias is corrected for by applying the common analyte internal standardization method approach. Comparison with other mass bias correction methods demonstrates the accuracy of the method. The average precision of delta(66)Zn determinations in aerosols is around 0.05 per thousand per atomic mass unit. The method was tested on aerosols collected in Sao Paulo City, Brazil. The measurements reveal significant variations in delta(66)Zn(Imperial) ranging between -0.96 and -0.37 per thousand in coarse and between -1.04 and 0.02 per thousand in fine particular matter. This variability suggests that Zn isotopic compositions distinguish atmospheric sources. The isotopic light signature suggests traffic as the main source. We present further delta(66)Zn(Imperial) data for the standard reference material NIST SRM 2783 (delta(66)Zn(Imperial) = 0.26 +/- 0.10 per thousand).

  4. Carbon isotopic analysis of atmospheric methane by isotope-ratio-monitoring gas chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Merritt, Dawn A.; Hayes, J. M.; Marais, David J. Des

    1995-01-01

    Less than 15 min are required for the determination of δ13CPDB with a precision of 0.2‰ (1σ, single measurement) in 5-mL samples of air containing CH4 at natural levels (1.7 ppm). An analytical system including a sample-introduction unit incorporating a preparative gas chromatograph (GC) column for separation of CH4 from N2, O2, and Ar is described. The 15-min procedure includes time for operation of that system, high-resolution chromatographic separation of the CH4, on-line combustion and purification of the products, and isotopic calibration. Analyses of standards demonstrate that systematic errors are absent and that there is no dependence of observed values of δ on sample size. For samples containing 100 ppm or more CH4, preconcentration is not required and the analysis time is less than 5 min. The system utilizes a commercially available, high-sensitivity isotope-ratio mass spectrometer. For optimal conditions of sample handling and combustion, performance of the system is within a factor of 2 of the shot-noise limit. The potential exists therefore for analysis of samples as small as 15 pmol CH4 with a standard deviation of <1‰.

  5. Carbon isotopic analysis of atmospheric methane by isotope-ratio-monitoring gas chromatography-mass spectrometry

    NASA Technical Reports Server (NTRS)

    Merritt, Dawn A.; Hayes, J. M.; Des Marais, David J.

    1995-01-01

    Less than 15 min are required for the determination of delta C(sub PDB)-13 with a precision of 0.2 ppt(1 sigma, single measurement) in 5-mL samples of air containing CH4 at natural levels (1.7 ppm). An analytical system including a sample-introduction unit incorporating a preparative gas chromatograph (GC) column for separation of CH4 from N2, O2, and Ar is described. The 15-min procedure includes time for operation of that system, high-resolution chromatographic separation of the CH4, on-line combustion and purification of the products, and isotopic calibration. Analyses of standards demonstrate that systematic errors are absent and that there is no dependence of observed values of delta on sample size. For samples containing 100 ppm or more CH4, preconcentration is not required and the analysis time is less than 5 min. The system utilizes a commercially available, high-sensitivity isotope-ratio mass spectrometer. For optimal conditions of smaple handling and combustion, performance of the system is within a factor of 2 of the shot-noise limit. The potential exists therefore for analysis of samples as small as 15 pmol CH4 with a standard deviation of less than 1 ppt.

  6. Utilizing Isotopic Uranium Ratios in Groundwater Evaluations at FUSRAP Sites

    SciTech Connect

    Frederick, W.T.; Keil, K.G.; Rhodes, M.C.; Peterson, J.M.; MacDonell, M.M.

    2007-07-01

    The U.S. Army Corps of Engineers Buffalo District is evaluating environmental radioactive contamination at several Formerly Utilized Sites Remedial Action Program (FUSRAP) sites throughout New York, Pennsylvania, Ohio, and Indiana. The investigations follow the process defined in the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Groundwater data from the Niagara Falls Storage Site (NFSS) in Lewiston, New York were evaluated for isotopic uranium ratios, specifically uranium-234 versus uranium-238 (U- 234 and U-238, respectively), and the results were presented at Waste Management 2006. Since uranium naturally occurs in all groundwater, it can be difficult to distinguish where low-concentration impacts from past releases differ from the high end of a site-specific natural background range. In natural groundwater, the ratio of U-234 to U-238 exceeds 1 (unity) due to the alpha particle recoil effect, in which U-234 is preferentially mobilized to groundwater from adjacent rock or soil. This process is very slow and may take hundreds to thousands of years before a measurable increase is seen in the natural isotopic ratio. If site releases are the source of uranium being measured in groundwater, the U-234 to U-238 ratio is commonly closer to 1, which normally reflects FUSRAP-related, uranium-contaminated wastes and soils. This lower ratio occurs because not enough residence time has elapsed since the 1940's and 1950's for the alpha particle recoil effect to have significantly altered the contamination-derived ratio. An evaluation of NFSS-specific and regional groundwater data indicate that an isotopic ratio of 1.2 has been identified as a signature value to help distinguish natural groundwater, which may have a broad background range, from zones impacted by past releases. (authors)

  7. Invited review article: Recent developments in isotope-ratio mass spectrometry for geochemistry and cosmochemistry.

    PubMed

    Ireland, Trevor R

    2013-01-01

    Mass spectrometry is fundamental to measurements of isotope ratios for applications in isotope geochemistry, geochronology, and cosmochemistry. Magnetic-sector mass spectrometers are most common because these provide the best precision in isotope ratio measurements. Where the highest precision is desired, chemical separation followed by mass spectrometric analysis is carried out with gas (noble gas and stable isotope mass spectrometry), liquid (inductively coupled plasma mass spectrometry), or solid (thermal ionization mass spectrometry) samples. Developments in in situ analysis, including ion microprobes and laser ablation inductively coupled plasma mass spectrometry, have opened up issues concerning homogeneity according to domain size, and allow ever smaller amounts of material to be analyzed. While mass spectrometry is built solidly on developments in the 20th century, there are new technologies that will push the limits in terms of precision, accuracy, and sample efficiency. Developments of new instruments based on time-of-flight mass spectrometers could open up the ultimate levels of sensitivity per sample atom.

  8. High-level direct-dynamics variational transition state theory calculations including multidimensional tunneling of the thermal rate constants, branching ratios, and kinetic isotope effects of the hydrogen abstraction reactions from methanol by atomic hydrogen.

    PubMed

    Meana-Pañeda, Rubén; Truhlar, Donald G; Fernández-Ramos, Antonio

    2011-03-07

    We report a detailed theoretical study of the hydrogen abstraction reaction from methanol by atomic hydrogen. The study includes the analysis of thermal rate constants, branching ratios, and kinetic isotope effects. Specifically, we have performed high-level computations at the MC3BB level together with direct dynamics calculations by canonical variational transition state theory (CVT) with the microcanonically optimized multidimensional tunneling (μOMT) transmission coefficient (CVT/μOMT) to study both the CH(3)OH+H→CH(2)OH+H(2) (R1) reaction and the CH(3)OH+H→CH(3)O+H(2) (R2) reaction. The CVT/μOMT calculations show that reaction R1 dominates in the whole range 298≤T (K)≤2500 and that anharmonic effects on the torsional mode about the C-O bond are important, mainly at high temperatures. The activation energy for the total reaction sum of R1 and R2 reactions changes substantially with temperature and, therefore, the use of straight-line Arrhenius plots is not valid. We recommend the use of new expressions for the total R1 + R2 reaction and for the R1 and R2 individual reactions.

  9. CCQM-K140: carbon stable isotope ratio delta values in honey

    NASA Astrophysics Data System (ADS)

    Dunn, P. J. H.; Goenaga-Infante, H.; Goren, A. C.; Şimşek, A.; Bilsel, M.; Ogrinc, N.; Armishaw, P.; Hai, L.

    2017-01-01

    As there can be small but measureable differences in isotope ratios between different sources of the same element/compound/material, isotope ratio measurements are applied in a number of different fields including archaeology, environmental science, geochemistry, forensic science and ecology. Isotope ratios for the light elements (H, C, N, O and S) are typically reported as δ-values which are isotope ratios expressed relative to an internationally agreed standard (this standard is the zero-point on the scale), although absolute isotope ratios which are traceable to the SI have also been reported. The IAWG has been granted a traceability exception for the use of arbitrary delta scales until SI traceability can be established at the required level of uncertainty but this goal is some years away. While the CCQM IAWG has previously organised several pilot studies on isotope ratio determination (CCQM-P75: Stable isotope delta values in methionine, 2006; CCQM-P105: Sr isotope ratios in wine, 2008; CCQM-K98: Pb isotope ratios in bronze with additional delta values in CCQM-P134, 2011), it has been a number of years since delta values of light elements have been considered and there has been no key comparison (KC). Therefore, the IAWG has included the need for a KC (CCQM-K140) based on an arbitrary delta scale in its program to support ongoing requirements to demonstrate core capabilities as well as specific claims of measurement capability (CMCs) in this area. The performance of all five of the CCQM-K140 participants was very good, illustrating their ability to obtain accurate results for carbon isotope ratios, within the calibration range afforded by internationally agreed reference materials (δ13CVPDB-LSVEC between ‑47.32 % and +535.3 %) with measurement uncertainties of between 0.08 and 0.28 %. This was despite the fact that no two participants used exactly the same approach in terms of instrumentation or data treatment. Main text To reach the main text of this

  10. Isotopic ratio of nitrogen on Titan: Photochemical interpretation

    NASA Astrophysics Data System (ADS)

    Krasnopolsky, Vladimir A.

    2016-12-01

    Nitrogen isotope fractionation in predissociation of N2 (Liang et al., 2007) is combined with production of N(4S), N(2D), and N+ in dissociation and dissociative ionization by the solar EUV photons, photoelectrons, magnetospheric electrons and protons, and cosmic rays from the photochemical model. The calculated 14N/15N ratio in nitriles is 57, in excellent agreement with the observed ratio in HCN. Loss of nitrogen in condensation and polymerization of nitriles is 392 g cm-2 Byr-1 with nitrogen isotope fractionation factor of 2.8. Loss of nitrogen by sputtering is 57 g cm-2 Byr-1 (De La Haye et al., 2007) with fractionation factor of 0.73 (Mandt et al., 2014). If the current loss was constant throughout the age of the Solar System, then the initial 14N/15N ratio on Titan is 129, similar to 127±32 for ammonia in comets (Rousselot et al., 2014). However, the solar EUV and wind were stronger from the young Sun, and this tends to further reduce the initial 14N/15N ratio. Nevertheless uncertainties of the problem and of the ratio in comets support the idea that nitrogen on Titan appeared as ammonia ice with 14N/15N similar to that in comets.

  11. Carbon isotopic ratio analysis by gas chromatography/combustion/isotope ratio mass spectrometry for the detection of gamma-hydroxybutyric acid (GHB) administration to humans.

    PubMed

    Saudan, Christophe; Augsburger, Marc; Mangin, Patrice; Saugy, Martial

    2007-01-01

    Since GHB (gamma-hydroxybutyric acid) is naturally produced in the human body, clinical and forensic toxicologists must be able to discriminate between endogenous levels and a concentration resulting from exposure. To suggest an alternative to the use of interpretative concentration cut-offs, the detection of exogenous GHB in urine specimens was investigated by means of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). GHB was isolated from urinary matrix by successive purification on Oasis MCX and Bond Elute SAX solid-phase extraction (SPE) cartridges prior to high-performance liquid chromatography (HPLC) fractioning using an Atlantis dC18 column eluted with a mixture of formic acid and methanol. Subsequent intramolecular esterification of GHB leading to the formation of gamma-butyrolactone (GBL) was carried out to avoid introduction of additional carbon atoms for carbon isotopic ratio analysis. A precision of 0.3 per thousand was determined using this IRMS method for samples at GHB concentrations of 10 mg/L. The (13)C/(12)C ratios of GHB in samples of subjects exposed to the drug ranged from -32.1 to -42.1 per thousand, whereas the results obtained for samples containing GHB of endogenous origin at concentration levels less than 10 mg/L were in the range -23.5 to -27.0 per thousand. Therefore, these preliminary results show that a possible discrimination between endogenous and exogenous GHB can be made using carbon isotopic ratio analyses.

  12. Measurement of stable carbon isotope ratios of non-methane hydrocarbons and halocarbons

    NASA Astrophysics Data System (ADS)

    Zuiderweg, A. T.

    2012-09-01

    Within the realm of volatile organic compounds, hydrocarbons and halocarbons form a sizable proportion of carbon input to the atmosphere. Within these compound categories, the light non-methane hydrocarbons (NMHC, two to seven carbon atoms) and monocarbon halocarbons have a special place as these have strong, if not exclusive, anthropogenic (human-caused) sources. With common atmospheric molar mixing ratios in the parts-per-trillion (10-12 mole/mole) to parts-per-billion (10-9 mole/mole) range, these trace gases, though decidedly minor constituants of the atmosphere, have diverse consequences due to their atmospheric presence and their removal processes. Effects range from causing ground level air pollution and resulting hazards to health, to contributing to anthropogenic climate change and the destruction of the ozone layer in the stratosphere, among many others. The existance of stable isotopes (otherwise identical atoms with varying amounts of neutrons that do not spontaneously disintegrate) in several elements relevant to atmospheric chemistry and physics is a boon to research. Their presence in molecules is detectable by mass and cause small intra- and intermolecular property changes. These changes range from the physical (e.g. boiling point variation) to the chemical (reaction rate variation) and can influence external interactions as well. The measurement of the ratio of a minor stable isotope of an element to the major one (the stable isotope ratio) can be used to establish source fingerprints, trace the interaction dynamics, and refine the understanding of the relative contribution of sources and sinks to the atmosphere as a whole. The stable minor stable isotope of carbon, 13C, has a natural abundance of approximately 1.1 %. It has a sufficient fractional mass difference from its major isotope as to cause significant effects, making it ideal for measuring the ratios and properties of hydro- and halocarbons. In order to enable a better understanding of the

  13. USE OF FATTY ACID STABLE CARBON ISOTOPE RATIO TO INDICATE MICROBIAL CARBON SOURCE IN TROPICAL SOILS

    EPA Science Inventory


    We use measurements of the concentration and stable carbon isotope ratio of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels, broad microbial community structure, and microbial carbon source. For studies of soil o...

  14. TOWARD A UNIQUE NITROGEN ISOTOPIC RATIO IN COMETARY ICES

    SciTech Connect

    Rousselot, Philippe; Cordier, Daniel; Mousis, Olivier; Pirali, Olivier; Vervloet, Michel; Martin-Drumel, Marie-Aline; Gruet, Sébastien; Jehin, Emmanuël; Hutsemékers, Damien; Manfroid, Jean; Arpigny, Claude; Decock, Alice

    2014-01-10

    Determination of the nitrogen isotopic ratios in different bodies of the solar system provides important information regarding the solar system's origin. We unambiguously identified emission lines in comets due to the {sup 15}NH{sub 2} radical produced by the photodissociation of {sup 15}NH{sub 3}. Analysis of our data has permitted us to measure the {sup 14}N/{sup 15}N isotopic ratio in comets for a molecule carrying the amine (-NH) functional group. This ratio, within the error, appears similar to that measured in comets in the HCN molecule and the CN radical, and lower than the protosolar value, suggesting that N{sub 2} and NH{sub 3} result from the separation of nitrogen into two distinct reservoirs in the solar nebula. This ratio also appears similar to that measured in Titan's atmospheric N{sub 2}, supporting the hypothesis that, if the latter is representative of its primordial value in NH{sub 3}, these bodies were assembled from building blocks sharing a common formation location.

  15. Determination of the sulfur isotope ratio in carbonyl sulfide using gas chromatography/isotope ratio mass spectrometry on fragment ions 32S+, 33S+, and 34S+.

    PubMed

    Hattori, Shohei; Toyoda, Akari; Toyoda, Sakae; Ishino, Sakiko; Ueno, Yuichiro; Yoshida, Naohiro

    2015-01-06

    Little is known about the sulfur isotopic composition of carbonyl sulfide (OCS), the most abundant atmospheric sulfur species. We present a promising new analytical method for measuring the stable sulfur isotopic compositions (δ(33)S, δ(34)S, and Δ(33)S) of OCS using nanomole level samples. The direct isotopic analytical technique consists of two parts: a concentration line and online gas chromatography-isotope ratio mass spectrometry (GC-IRMS) using fragmentation ions (32)S(+), (33)S(+), and (34)S(+). The current levels of measurement precision for OCS samples greater than 8 nmol are 0.42‰, 0.62‰, and 0.23‰ for δ(33)S, δ(34)S, and Δ(33)S, respectively. These δ and Δ values show a slight dependence on the amount of injected OCS for volumes smaller than 8 nmol. The isotope values obtained from the GC-IRMS method were calibrated against those measured by a conventional SF6 method. We report the first measurement of the sulfur isotopic composition of OCS in air collected at Kawasaki, Kanagawa, Japan. The δ(34)S value obtained for OCS (4.9 ± 0.3‰) was lower than the previous estimate of 11‰. When the δ(34)S value for OCS from the atmospheric sample is postulated as the global signal, this finding, coupled with isotopic fractionation for OCS sink reactions in the stratosphere, explains the reported δ(34)S for background stratospheric sulfate. This suggests that OCS is a potentially important source for background (nonepisodic or nonvolcanic) stratospheric sulfate aerosols.

  16. Variation in strontium isotope ratios of archaeological fauna in the Midwestern United States: a preliminary study

    USGS Publications Warehouse

    Hedman, Kristin M.; Curry, B. Brandon; Johnson, Thomas M.; Fullagar, Paul D.; Emerson, Thomas E.

    2009-01-01

    Strontium isotope values (87Sr/86Sr) in bone and tooth enamel have been used increasingly to identify non-local individuals within prehistoric human populations worldwide. Archaeological research in the Midwestern United States has increasingly highlighted the role of population movement in affecting interregional cultural change. However, the comparatively low level of geologic variation in the Midwestern United States might suggest a corresponding low level of strontium variation, and calls into question the sensitivity of strontium isotopes to identify non-local individuals in this region. Using strontium isotopes of archaeological fauna, we explore the degree of variability in strontium ratios across this region. Our results demonstrate measurable variation in strontium ratios and indicate the potential of strontium analysis for addressing questions of origin and population movement in the Midwestern United States.

  17. Isotope ratio monitoring gas chromatography/Mass spectrometry of D/H by high temperature conversion isotope ratio mass spectrometry.

    PubMed

    Hilkert; Douthitt; Schlüter; Brand

    1999-07-01

    Of all the elements, hydrogen has the largest naturally occurring variations in the ratio of its stable isotopes (D/H). It is for this reason that there has been a strong desire to add hydrogen to the list of elements amenable to isotope ratio monitoring gas chromatography/mass spectrometry (irm-GC/MS). In irm-GC/MS the sample is entrained in helium as the carrier gas, which is also ionized and separated in the isotope ratio mass spectrometer (IRMS). Because of the low abundance of deuterium in nature, precise and accurate on-line monitoring of D/H ratios with an IRMS requires that low energy helium ions be kept out of the m/z 3 collector, which requires the use of an energy filter. A clean mass 3 (HD(+.)) signal which is independent of a large helium load in the electron impact ion source is essential in order to reach the sensitivity required for D/H analysis of capillary GC peaks. A new IRMS system, the DELTA(plus)XL(trade mark), has been designed for high precision, high accuracy measurements of transient signals of hydrogen gas. It incorporates a retardation lens integrated into the m/z 3 Faraday cup collector. Following GC separation, the hydrogen bound in organic compounds must be quantitatively converted into H(2) gas prior to analysis in the IRMS. Quantitative conversion is achieved by high temperature conversion (TC) at temperatures >1400 degrees C. Measurements of D/H ratios of individual organic compounds in complicated natural mixtures can now be made to a precision of 2 per thousand (delta notation) or, better, with typical sample amounts of approximately 200 ng per compound. Initial applications have focused on compounds of interest to petroleum research (biomarkers and natural gas components), food and flavor control (vanillin and ethanol), and metabolic studies (fatty acids and steroids). Copyright 1999 John Wiley & Sons, Ltd.

  18. Carbon isotope ratios and isotopic correlations between components in fruit juices

    NASA Astrophysics Data System (ADS)

    Wierzchnicki, Ryszard

    2013-04-01

    Nowadays food products are defined by geographical origin, method of production and by some regulations concerning terms of their authenticity. Important data for confirm the authenticity of product are providing by isotopic methods of food control. The method checks crucial criteria which characterize the authenticity of inspected product. The European Union Regulations clearly show the tendency for application of the isotopic methods for food authenticity control (wine, honey, juice). The aim of the legislation steps is the protection of European market from possibility of the commercial frauds. Method of isotope ratio mass spectrometry is very effective tool for the use distinguishably the food products of various geographical origin. The basic problem for identification of the sample origin is the lack of databases of isotopic composition of components and information about the correlations of the data. The subject of the work was study the isotopic correlations existing between components of fruits. The chemical and instrumental methods of separation: water, sugars, organic acids and pulp from fruit were implemented. IRMS technique was used to measure isotopic composition of samples. The final results for original samples of fruits (apple, strawberry etc.) will be presented and discussed. Acknowledgement: This work was supported by the Polish Ministry of Science and Higher Education under grant NR12-0043-10/2010.

  19. Progress in AMS measurement of U isotope ratios in nanogram U samples

    NASA Astrophysics Data System (ADS)

    Dong, Kejun; He, Ming; Wang, Chen; Zhao, Xinhong; Li, Lili; Zhao, Yonggang; Wang, Xianggao; Shen, Hongtao; Wang, Xiaoming; Pang, Fangfang; Xu, Yongning; Zhao, Qingzhang; Dou, Liang; Yang, Xuran; Wu, Shaoyong; Lin, Deyu; Li, Kangning; You, Qubo; Bao, Yiwen; Hu, Yueming; Xia, Qingliang; Yin, Xinyi; Jiang, Shan

    2015-10-01

    The determination of uranium isotopic composition in ultra-trace U samples is very important in different fields, especially for the nuclear forensics. A new Accelerator Mass Spectrometry (AMS) technique has been developed for the measurement of uranium isotopic ratios in ng level uranium samples at China Institute of Atomic Energy (CIAE). Recently, the method was further optimized and developed by using a series of blank and standard samples. The results show that the 236U at the femtogram level can be determined in nanogram U samples by the newly developed AMS technique at CIAE. The experimental setup, performances and results will be detailed in this contribution.

  20. Isotopic ratio outlier analysis global metabolomics of Caenorhabditis elegans.

    PubMed

    Stupp, Gregory S; Clendinen, Chaevien S; Ajredini, Ramadan; Szewc, Mark A; Garrett, Timothy; Menger, Robert F; Yost, Richard A; Beecher, Chris; Edison, Arthur S

    2013-12-17

    We demonstrate the global metabolic analysis of Caenorhabditis elegans stress responses using a mass-spectrometry-based technique called isotopic ratio outlier analysis (IROA). In an IROA protocol, control and experimental samples are isotopically labeled with 95 and 5% (13)C, and the two sample populations are mixed together for uniform extraction, sample preparation, and LC-MS analysis. This labeling strategy provides several advantages over conventional approaches: (1) compounds arising from biosynthesis are easily distinguished from artifacts, (2) errors from sample extraction and preparation are minimized because the control and experiment are combined into a single sample, (3) measurement of both the molecular weight and the exact number of carbon atoms in each molecule provides extremely accurate molecular formulas, and (4) relative concentrations of all metabolites are easily determined. A heat-shock perturbation was conducted on C. elegans to demonstrate this approach. We identified many compounds that significantly changed upon heat shock, including several from the purine metabolism pathway. The metabolomic response information by IROA may be interpreted in the context of a wealth of genetic and proteomic information available for C. elegans . Furthermore, the IROA protocol can be applied to any organism that can be isotopically labeled, making it a powerful new tool in a global metabolomics pipeline.

  1. Isotopic Ratio Outlier Analysis Global Metabolomics of Caenorhabditis elegans

    PubMed Central

    Szewc, Mark A.; Garrett, Timothy; Menger, Robert F.; Yost, Richard A.; Beecher, Chris; Edison, Arthur S.

    2014-01-01

    We demonstrate the global metabolic analysis of Caenorhabditis elegans stress responses using a mass spectrometry-based technique called Isotopic Ratio Outlier Analysis (IROA). In an IROA protocol, control and experimental samples are isotopically labeled with 95% and 5% 13C, and the two sample populations are mixed together for uniform extraction, sample preparation, and LC-MS analysis. This labeling strategy provides several advantages over conventional approaches: 1) compounds arising from biosynthesis are easily distinguished from artifacts, 2) errors from sample extraction and preparation are minimized because the control and experiment are combined into a single sample, 3) measurement of both the molecular weight and the exact number of carbon atoms in each molecule provides extremely accurate molecular formulae, and 4) relative concentrations of all metabolites are easily determined. A heat shock perturbation was conducted on C. elegans to demonstrate this approach. We identified many compounds that significantly changed upon heat shock, including several from the purine metabolism pathway, which we use to demonstrate the approach. The metabolomic response information by IROA may be interpreted in the context of a wealth of genetic and proteomic information available for C. elegans. Furthermore, the IROA protocol can be applied to any organism that can be isotopically labeled, making it a powerful new tool in a global metabolomics pipeline. PMID:24274725

  2. Carbon isotope ratios and impurities in diamonds from Southern Africa

    NASA Astrophysics Data System (ADS)

    Kidane, Abiel; Koch-Müller, Monika; Morales, Luiz; Wiedenbeck, Michael; De Wit, Maarten

    2015-04-01

    We are investigating the sources of diamonds from southern Africa by studying both their carbon isotopic composition and chemical impurities. Our samples include macro-sized diamonds from River Ranch kimberlite in Zimbabwe and the Helam and Klipspringer kimberlitic deposits from South Africa, as well as micro-sized diamonds from Klipspringer and Premier kimberlites in South Africa. We have characterized the samples for their structurally bounded nitrogen, hydrogen and platelets defect using a Fourier Transmission Infrared Spectroscopy (FTIR). Using the DiaMap routine, open source software (Howell et al., 2012), IR spectra were deconvulated and quantified for their nitrogen (A, B and D components) and hydrogen contents. High to moderate nitrogen concentrations (1810 to 400 µg/g; 400 to 50 µg/g respectively) were found in diamonds from Klipspringer and Helam. Moderate to low (<50 µg/g) nitrogen concentrations were observed in diamonds from Premier and River Ranch. Type II diamonds, i.e. diamonds with no N impurities, which are presumed to have been derived from ultramafic sources, are found in the River Ranch deposit. The macro- and micro-size diamonds from the Klipspringer deposit display similar nitrogen defects, with higher nitrogen concentration and more frequent D components found in the macro-size diamonds. One of the first steps towards reliable carbon isotope studies is the development of calibration materials for SIMS carbon isotopic analyses. We have investigated candidate materials both from a polycrystalline synthetic diamond sheet and two natural gem quality diamonds from Juina (Brazil). Electron-based images of the synthetic diamond sheet, obtained using GFZ Potsdam's dual beam FIB instrument, show many diamond grains with diameters greater than 35 µm. SIMS testing of the isotopic homogeneity of the back and front sides of the synthetic sheets reveal similar 13C/12C ratio within a RSD of <1 ‰ . SIMS isotopic analyses of the two natural diamond RMs

  3. The lithium isotopic ratio in very metal-poor stars

    NASA Astrophysics Data System (ADS)

    Lind, K.; Melendez, J.; Asplund, M.; Collet, R.; Magic, Z.

    2013-06-01

    Context. Un-evolved, very metal-poor stars are the most important tracers of the cosmic abundance of lithium in the early universe. Combining the standard Big Bang nucleosynthesis model with Galactic production through cosmic ray spallation, these stars at [Fe / H] < - 2 are expected to show an undetectably small 6Li / 7Li isotopic signature. Evidence to the contrary may necessitate an additional pre-galactic production source or a revision of the standard model of Big Bang nucleosynthesis. It would also cast doubts on Li depletion from stellar atmospheres as an explanation for the factor 3-5 discrepancy between the predicted primordial 7Li from the Big Bang and the observed value in metal-poor dwarf/turn-off stars. Aims: We revisit the isotopic analysis of four halo stars, two with claimed 6Li-detections in the literature, to investigate the influence of improved model atmospheres and line formation treatment. Methods: For the first time, a combined 3D, non-local thermodynamic equilibrium (NLTE) modelling technique for Li, Na, and Ca lines is utilised to constrain the intrinsic line-broadening and to determine the Li isotopic ratio. We discuss the influence of 3D NLTE effects on line profile shapes and assess the realism of our modelling using the Ca excitation and ionisation balance. Results: By accounting for NLTE line formation in realistic 3D hydrodynamical model atmospheres, we can model the Li resonance line and other neutral lines with a consistency that is superior to LTE, with no need for additional line asymmetry caused by the presence of 6Li. Contrary to the results from 1D and 3D LTE modelling, no star in our sample has a significant (2σ) detection of the lighter isotope in NLTE. Over a large parameter space, NLTE modelling systematically reduces the best-fit Li isotopic ratios by up to five percentage points. As a bi-product, we also present the first ever 3D NLTE Ca and Na abundances of halo stars, which reveal significant departures from LTE

  4. Last Glacial Maximum and deglacial abyssal seawater oxygen isotopic ratios

    NASA Astrophysics Data System (ADS)

    Wunsch, Carl

    2016-06-01

    An earlier analysis of pore-water salinity (chlorinity) in two deep-sea cores, using terminal constraint methods of control theory, concluded that although a salinity amplification in the abyss was possible during the LGM, it was not required by the data. Here the same methodology is applied to δ18Ow in the upper 100 m of four deep-sea cores. An ice volume amplification to the isotopic ratio is, again, consistent with the data but not required by it. In particular, results are very sensitive, with conventional diffusion values, to the assumed initial conditions at -100 ky and a long list of noise (uncertainty) assumptions. If the calcite values of δ18O are fully reliable, then published enriched values of the ratio in seawater are necessary to preclude sub-freezing temperatures, but the seawater δ18O in pore fluids does not independently require the conclusion.

  5. Childhood lead exposure in an industrial town in China: coupling stable isotope ratios with bioaccessible lead.

    PubMed

    Li, Hong-Bo; Chen, Kai; Juhasz, Albert L; Huang, Lei; Ma, Lena Q

    2015-04-21

    Fingerprinting based on stable isotopes of lead (Pb) in blood and environmental media helps to identify Pb exposure pathways in children. However, previous studies used stable isotopes of total Pb in media. In this study, a wire rope production town in China (Zhuhang) was selected for investigating the effectiveness of using isotope ratios in bioaccessible Pb to identify childhood Pb exposure pathways. Blood Pb levels of 115 children in Zhuhang were 1.7-20.4 μg dL(-1), averaging 6.1 ± 3.2 μg dL(-1) (mean ± standard deviation), and were ∼1.6 times the national average in China (3.9 ± 1.8 μg dL(-1)). Among different environmental media (housedust, soil, PM10, vegetables, rice, and drinking water), housedust (695 ± 495 mg kg(-1)) and vegetables [0.36 ± 0.40 mg (kg of fresh weight)(-1)] contained elevated Pb concentrations. The isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) of total Pb were the highest in housedust (0.8587 ± 0.0039 and 2.1049 ± 0.0087) but lower than blood Pb ratios (0.8634 ± 0.0027 and 2.1244 ± 0.0061). When using bioaccessible Pb in housedust (0.8639 ± 0.0018 and 2.1171 ± 0.0036), the isotope ratios overlapped with blood Pb ratios, suggesting that incidental ingestion of housedust was the predominant contributor to children's blood Pb. Coupling the stable isotope technique with bioaccessible Pb is more reliable for identifying Pb exposure pathways than total Pb determinations.

  6. Activities of Pu and Am isotopes and isotopic ratios in a soil contaminated by weapons-grade plutonium.

    PubMed

    Lee, M H; Clark, S B

    2005-08-01

    An accident and fire at the former McGuire Air Force Base and Boeing Michigan Aeronautical Research Center (BOMARC) site in New Jersey resulted in dispersion of weapons-grade plutonium in particulate form to the local environment. Soil samples collected at the BOMARC site were measured for their activities and isotopic ratios of Pu and Am isotopes by radioanalytical techniques. The activities of the Pu and Am isotopes in the BOMARC soil were markedly higher than fallout levels, and they decreased nearly exponentially with increasing particle size of the soil. The measured (241)Am activity was compared to calculated values based on decay of (241)Pu. The activity ratios of (238)Pu/(239,240)Pu, (241)Pu/(239,240)Pu, and (241)Am/(239,240)Pu observed in the BOMARC soil were much lower than those attributed to nuclear reprocessing plants and Chernobyl fallout. From the activity ratios of (241)Pu/(239,240)Pu and (241)Am/(239,240)Pu, the origin of the Pu isotopes was identified as weapons-grade and the time since production of the material was estimated. Furthermore, the atomic ratio of (240)Pu/(239)Pu in the BOMARC soil was remarkably lower than the fallout value influenced by nuclear weapons testing and the Chernobyl accident. The atomic ratio of (240)Pu/(239)Pu was very close to the value of the weapons-grade Pu detected from the Thule accident in Greenland. This work demonstrates the utility of radioanalytical measurements and decay calculations for defining characteristics of the source term and discriminating multiple processes that contribute to a source. Such an approach would also be needed to respond to a terrorist event involving an improvised nuclear device or radiological dispersal device.

  7. Stable isotope analysis of white paints and likelihood ratios.

    PubMed

    Farmer, N; Meier-Augenstein, W; Lucy, D

    2009-06-01

    Architectural paints are commonly found as trace evidence at scenes of crime. Currently the most widely used technique for the analysis of architectural paints is Fourier Transformed Infra-Red Spectroscopy (FTIR). There are, however, limitations to the forensic analysis of white paints, and the ability to discriminate between samples. Isotope ratio mass spectrometry (IRMS) has been investigated as a potential tool for the analysis of architectural white paints, where no preparation of samples prior to analysis is required. When stable isotope profiles (SIPs) are compared, there appears to be no relationship between paints from the same manufacturer, or between paints of the same type. Unlike existing techniques, IRMS does not differentiate resin samples solely on the basis of modifier or oil-type, but exploits additional factors linked to samples such as geo-location where oils added to alkyd formulations were grown. In combination with the use of likelihood ratios, IRMS shows potential, with a false positive rate of 2.6% from a total of 1275 comparisons.

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

    NASA Astrophysics Data System (ADS)

    Annewandter, R.

    2013-12-01

    The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced soil gas sampling during On-Site inspections. Gas transport has been widely studied with different numerical codes. However, gas transport of all radioxenons in the post-detonation regime and their possible fractionation is still neglected in the open literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radioxenons, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different diffusivities due to mass differences between the radioxenons. A previous study showed surface arrival time of a chemically inert gaseous tracer is affected by its diffusivity. They observed detectable amount for SF6 50 days after detonation and 375 days for He-3. They predict 50 and 80 days for Xe-133 and Ar-37 respectively. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations , fracture propagation in fractured, porous media, Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic

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

    PubMed

    Fekiacova, Z; Cornu, S; Pichat, S

    2015-06-01

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

  10. Isotopic ratio correlation for the isotopic composition analysis of plutonium in Am-Pu mixed samples having high americium content.

    PubMed

    Patra, Sabyasachi; Agarwal, Chhavi; Chaudhury, Sanhita; Newton Nathaniel, T; Gathibandhe, M; Goswami, A

    2013-08-01

    Interference of high amount of americium in the plutonium isotopic composition analysis has been studied by simulating gamma-ray spectra for Am-Pu samples over a wide composition range (5-97% (241)Am) for both power and research reactor grade plutonium. An alternate way for isotopic composition analysis has been proposed by correlating the isotopic ratios available in our old database with the experimentally obtained (241)Pu/(239)Pu isotopic ratio. The proposed method has been validated using simulated spectra of known isotopic compositions.

  11. Forensic applications of light-element stable isotope ratios of Ricinus communis seeds and ricin preparations.

    PubMed

    Kreuzer, Helen W; West, Jason B; Ehleringer, James R

    2013-01-01

    Seeds of the castor plant Ricinus communis are of forensic interest because they are the source of the poison ricin. We tested whether stable isotope ratios of castor seeds and ricin preparations can be used as a forensic signature. We collected over 300 castor seed samples worldwide and measured the C, N, O, and H isotope ratios of the whole seeds and oil. We prepared ricin by three different procedures, acetone extraction, salt precipitation, and affinity chromatography, and compared their isotope ratios to those of the source seeds. The N isotope ratios of the ricin samples and source seeds were virtually identical. Therefore, N isotope ratios can be used to correlate ricin prepared by any of these methods to source seeds. Further, stable isotope ratios distinguished >99% of crude and purified ricin protein samples in pairwise comparison tests. Stable isotope ratios therefore constitute a valuable forensic signature for ricin preparations.

  12. Mathematical modeling of stable carbon isotope ratios in natural gases^@?

    NASA Astrophysics Data System (ADS)

    Tang, Y.; Perry, J. K.; Jenden, P. D.; Schoell, M.

    2000-08-01

    A new approach is presented for mathematical modeling of stable carbon isotope ratios in hydrocarbon gases based on both theoretical and experimental data. The kinetic model uses a set of parallel first-order gas generation reactions in which the relative cracking rates of isotopically substituted (k∗) and unsubstituted (k) bonds are represented by the equation k∗/k=(Af∗/Af) exp(-ΔEa/RT), where R is the gas constant and T is temperature. Quantum chemistry calculations have been used to estimate the entropic (A f∗/A f) and enthalpic (ΔEa) terms for homolytic bond cleavage in a variety of simple molecules. For loss of a methyl group from a short-chain n-alkane (≤ C 6), for example, we obtain an average ΔEa of 42.0 cal/mol and an average A f∗/A f of 1.021. Expressed differently, 13C-methane generation is predicted to be 2.4% (24‰) slower than 12C-methane generation (from a short-chain n-alkane) in a sedimentary basin at 200°C but only 0.7% (7‰) slower in a laboratory heating experiment at 500°C. Similar calculations carried out for homolytic bond cleavage in other molecules show that with few exceptions, ΔEa varies between 0 and 60 cal/mol and A f∗/A f between 1.00 and 1.04. Examination of this larger data set reveals: (1) a weak sigmoid relationship between ΔEa and bond dissociation energy; and (2) a strong positive correlation between ΔEa and A f∗/A f. The significance of these findings is illustrated by fitting a kinetic model to chemical and isotopic data for the generation of methane from n-octadecane under isothermal closed-system conditions. For a specific temperature history, the fitted model provides quantitative relationships among methane carbon isotope composition, total methane yield and methane generation rate which may have relevance to the cracking of oil-prone kerogens and crude oil. The observed variability of the kinetic reactivity of various methane source rocks highlights the need to apply and adequately calibrate such

  13. Stable lead isotope ratios in Alaskan arctic aerosols

    NASA Astrophysics Data System (ADS)

    Sturges, W. T.; Hopper, J. F.; Barrie, L. A.; Schnell, R. C.

    Aerosol samples collected at Barrow, Alaska, during February and March 1990 were found to have uniform stable lead isotope compositions. The mean 208Pb/ 207Pb ratio was 2.423±0.009 and the mean 206Pb/ 207Pb ratio was 1.161±0.014. The latter ratio is essentially the same as that obtained from an earlier study of aerosols at two Canadian stations in the High Arctic and is typical of, but not unique to, Eurasian sources of atmospheric lead. Further discriminating power was available in this study through the inclusion of 208Pb/ 207Pb ratios, which provided additional evidence that the former Soviet Union and eastern Europe are major contributors to atmospheric particulate lead in the Alaskan Arctic, accounting for around two-thirds of the particulate lead measured at Barrow. The remaining third of the lead is attributed to west European sources. There was no evidence for a substantial North American component, other than local contamination.

  14. Towards a better understanding of magnesium-isotope ratios from marine skeletal carbonates

    NASA Astrophysics Data System (ADS)

    Hippler, Dorothee; Buhl, Dieter; Witbaard, Rob; Richter, Detlev K.; Immenhauser, Adrian

    2009-10-01

    This study presents magnesium stable-isotope compositions of various biogenic carbonates of several marine calcifying organisms and an algae species, seawater samples collected from the western Dutch Wadden Sea, and reference materials. The aim of this study is to explore the influence of mineralogy, taxonomy and environmental factors (e.g., seawater isotopic composition, temperature, salinity) on magnesium-isotopic (δ 26Mg) ratios of skeletal carbonates. Using high-precision multi-collector inductively coupled plasma mass spectrometry, we observed that the magnesium-isotopic composition of seawater from the semi-enclosed Dutch Wadden Sea is identical to that of open marine seawater. We further found that a considerable component of the observed variability in δ 26Mg values of marine skeletal carbonates can be attributed to differences in mineralogy. Furthermore, magnesium-isotope fractionation is species-dependent, with all skeletal carbonates being isotopically lighter than seawater. While δ 26Mg values of skeletal aragonite and high-magnesium calcite of coralline red algae indicate the absence or negligibility of metabolic influences, the δ 26Mg values of echinoids, brachiopods and bivalves likely result from a taxon-specific level of control on Mg-isotope incorporation during biocalcification. Moreover, no resolvable salinity and temperature effect were observed for coralline red algae and echinoids. In contrast, Mg-isotope data of bivalves yield ambiguous results, which require further validation. The data presented here, point to a limited use of Mg isotopes as temperature proxy, but highlight the method's potential as tracer of seawater chemistry through Earth's history.

  15. Tunable Diode Laser Measurements of Leaf-scale Carbon Isotope Discrimination and Ecosystem Respired Carbon and Oxygen Isotope Ratios in a Semi-arid Woodland

    NASA Astrophysics Data System (ADS)

    McDowell, N.; Chris, B.; Hanson, D.; Kern, S.; Meyer, C.; Pockman, W.; Powers, H.

    2005-12-01

    We present results and speculative interpretation of leaf-level carbon isotope discrimination and ecosystem respired carbon and oxygen isotope ratios from a semi-arid, C3/C4 woodland located in northern New Mexico, USA. Overstory leaf area index (LAI) is dominated by live juniper (Juniperus monosperma) trees with an LAI value of approximately 1.0 m2 per m2 ground area, and has a seasonally dynamic understory of mixed C3 forbs and C4 grasses and cacti, with a maximum LAI of 0.30 m2 per m2 ground area. Ecosystem respired carbon isotope ratios showed values characteristic of C3 dominated photosynthesis (Keeling plot intercepts of -35 to -22 per mil). Seasonal variation was typical of that found in wetter, C3 dominated forests, as was the dependence on climate (e.g. relationships with vapor pressure deficit, soil water content, and canopy conductance). Leaf-level carbon isotope discrimination of the junipers, measured by coupling a Li-Cor 6400 photosynthesis system to the TDL, provided discrimination-Ci and discrimination-vpd relationships consistent with measured ecosystem respired carbon isotope ratios. The oxygen isotope ratio of ecosystem respiration was dependent on rain water isotope composition, but was correlated with soil water content during rain-free periods. The cumulative effect of vapor pressure deficit after a rain event was tightly correlated with the oxygen isotope ratio of ecosystem respiration, suggesting the primary drivers are evaporative enrichment of soil water and perhaps nocturnal leaf enrichment. Instrument precision for carbon and oxygen isotope ratios of carbon dioxide is 0.06 to 0.18 per mil; however, overall precision is somewhat lower due to pressure and sampling effects.

  16. Investigation of mass dependence effects for the accurate determination of molybdenum isotope amount ratios by MC-ICP-MS using synthetic isotope mixtures.

    PubMed

    Malinovsky, Dmitry; Dunn, Philip J H; Petrov, Panayot; Goenaga-Infante, Heidi

    2015-01-01

    Methodology for absolute Mo isotope amount ratio measurements by multicollector inductively coupled plasma-mass spectrometry (MC-ICP-MS) using calibration with synthetic isotope mixtures (SIMs) is presented. For the first time, synthetic isotope mixtures prepared from seven commercially available isotopically enriched molybdenum metal powders ((92)Mo, (94)Mo, (95)Mo, (96)Mo, (97)Mo, (98)Mo, and (100)Mo) are used to investigate whether instrumental mass discrimination of Mo isotopes in MC-ICP-MS is consistent with mass-dependent isotope distribution. The parent materials were dissolved and mixed as solutions to obtain mixtures with accurately known isotope amount ratios. The level of elemental impurities in the isotopically enriched molybdenum metal powders was quantified by ICP-MS by using both high-resolution and reaction cell instruments to completely resolve spectral interferences. The Mo isotope amount ratio values with expanded uncertainty (k = 2), determined by MC-ICP-MS for a high-purity Mo rod from Johnson Matthey, were as follows: (92)Mo/(95)Mo = 0.9235(9), (94)Mo/(95)Mo = 0.5785(8), (96)Mo/(95)Mo = 1.0503(9), (97)Mo/(95)Mo = 0.6033(6), (98)Mo/(95)Mo = 1.5291(20), and (100)Mo/(95)Mo = 0.6130(7). A full uncertainty budget for the measurements is presented which shows that the largest contribution to the uncertainty budget comes from correction for elemental impurities (∼51%), followed by the contribution from weighing operations (∼26 %). The atomic weight of molybdenum was calculated to be 95.947(2); the uncertainty in parentheses is expanded uncertainty with the coverage factor of 2. A particular advantage of the developed method is that calibration factors for all six Mo isotope amount ratios, involving the (95)Mo isotope, were experimentally determined. This allows avoiding any assumption on mass-dependent isotope fractions in MC-ICP-MS, inherent to the method of double spike previously used for Mo isotope amount ratio

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

    NASA Astrophysics Data System (ADS)

    Annewandter, Robert

    2014-05-01

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

  18. Nitrogen isotopic ratios in fecal pellets produced by marine zooplankton

    SciTech Connect

    Altabet, M.A. ); Small, L.F. )

    1990-01-01

    At each site and in every season studied, zooplankton in the upper ocean produced fecal pellets that were 1.3% lower in {delta}{sup 15}N than their body tissue but 2.2% higher than their apparent food source. {sup 14}N-containing molecules are evidently preferentially assimilated in zooplankton intestinal tracts, though other isotopic effects must account for the enrichment in {sup 15}N of these organisms relative to their food. These results also show zooplankton to be important modifiers of nitrogen isotopic ratios for marine particulate matter. {delta}{sup 15}N values for sinking particles and fecal pellets are similar, supporting the perspective that macrozooplankton are important factors in producing and processing particles that sink into the ocean's interior and sediments. In contrast, the relationship in {delta}{sup 15}N between fecal pellets and suspended particles in the euphotic zone is more variable. It appears that zooplankton select food particles of varying {delta}{sup 15}N from the suspended particle pool. These results suggest that both zooplankton feeding behavior and their digestive chemistry are important in determining the composition of sinking particulate matter in the ocean with respect to the suspended particle source in the euphotic zone.

  19. Carbon and Oxygen Isotopic Ratios for Nearby Miras

    NASA Astrophysics Data System (ADS)

    Hinkle, Kenneth H.; Lebzelter, Thomas; Straniero, Oscar

    2016-07-01

    Carbon and oxygen isotopic ratios are reported for a sample of 46 Mira and SRa-type variable asymptotic giant branch (AGB) stars. Vibration-rotation first and second-overtone CO lines in 1.5-2.5 μm spectra were measured to derive isotopic ratios for 12C/13C, 16O/17O, and 16O/18O. Comparisons with previous measurements for individual stars and with various samples of evolved stars, as available in the extant literature, are discussed. Models for solar composition AGB stars of different initial masses are used to interpret our results. We find that the majority of M-stars have main sequence masses ≤2 M ⊙ and have not experienced sizable third dredge-up (TDU) episodes. The progenitors of the four S-type stars in our sample are slightly more massive. Of the six C-stars in the sample three have clear evidence relating their origin to the occurrence of TDU. Comparisons with O-rich presolar grains from AGB stars that lived before the formation of the solar system reveal variations in the interstellar medium chemical composition. The present generation of low-mass AGB stars, as represented by our sample of long period variables (LPVs), shows a large spread of 16O/17O ratios, similar to that of group 1 presolar grains and in agreement with theoretical expectations for the composition of mass 1.2-2 M ⊙ stars after the first dredge-up. In contrast, the 16O/18O ratios of present-day LPVs are definitely smaller than those of group 1 grains. This is most probably a consequence of the the decrease with time of the 16O/18O ratio in the interstellar medium due to the chemical evolution of the Milky Way. One star in our sample has an O composition similar to that of group 2 presolar grains originating in an AGB star undergoing extra-mixing. This may indicate that the extra-mixing process is hampered at high metallicity, or, equivalently, favored at low metallicity. Similarly to O-rich grains, no star in our sample shows evidence of hot bottom burning, which is expected for

  20. High-Precision (MC-ICPMS) Isotope Ratio Analysis Reveals Contrasting Sources of Elevated Blood Lead Levels of an Adult with Retained Bullet Fragments, and of His Child, in Milwaukee, Wisconsin.

    PubMed

    Smith, Kate E; Shafer, Martin M; Weiss, Debora; Anderson, Henry A; Gorski, Patrick R

    2017-05-01

    Exposure to the neurotoxic element lead (Pb) continues to be a major human health concern, particularly for children in US urban settings, and the need for robust tools for assessment of exposure sources has never been greater. The latest generation of multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) instrumentation offers the capability of using Pb isotopic signatures as a tool for environmental source tracking in public health. We present a case where MC-ICPMS was applied to isotopically resolve Pb sources in human clinical samples. An adult male and his child residing in Milwaukee, Wisconsin, presented to care in August 2015 with elevated blood lead levels (BLLs) (>200 μg/dL for the adult and 10 μg/dL for the child). The adult subject is a gunshot victim who had multiple bullet fragments embedded in soft tissue of his thigh for approximately 10 years. This study compared the high-precision isotopic fingerprints (<1 ‰ 2σ external precision) of Pb in the adult's and child's whole blood (WB) to the following possible Pb sources: a surgically extracted bullet fragment, household paint samples and tap water, and a Pb water-distribution pipe removed from servicing a house in the same neighborhood. Pb in the bullet and adult WB were nearly isotopically indistinguishable (matching within 0.05-0.56 ‰), indicating that bullet fragments embedded in soft tissue could be the cause of both acute and chronic elevated blood Pb levels. Among other sources investigated, no single source dominated the child's exposure profile as reflected in the elevated BLL.

  1. Demonstration of compound-specific isotope analysis of hydrogen isotope ratios in chlorinated ethenes.

    PubMed

    Kuder, Tomasz; Philp, Paul

    2013-02-05

    High-temperature pyrolysis conversion of organic analytes to H(2) in hydrogen isotope ratio compound-specific isotope analysis (CSIA) is unsuitable for chlorinated compounds such as trichloroethene (TCE) and cis-1,2-dichloroethene (DCE), due to competition from HCl formation. For this reason, the information potential of hydrogen isotope ratios of chlorinated ethenes remains untapped. We present a demonstration of an alternative approach where chlorinated analytes reacted with chromium metal to form H(2) and minor amounts of HCl. The values of δ(2)H were obtained at satisfactory precision (± 10 to 15 per thousand), however the raw data required daily calibration by TCE and/or DCE standards to correct for analytical bias that varies over time. The chromium reactor has been incorporated into a purge and trap-CSIA method that is suitable for CSIA of aqueous environmental samples. A sample data set was obtained for six specimens of commercial product TCE. The resulting values of δ(2)H were between -184 and +682 ‰, which significantly widened the range of manufactured TCE δ(2)H signatures identified by past work. The implications of this finding to the assessment of TCE contamination are discussed.

  2. Determination of triple oxygen isotopic compositions of nitrate by using continuous-flow isotope ratio MS.

    NASA Astrophysics Data System (ADS)

    Komatsu, D. D.; Ohkubo, S.; Ishimura, T.; Nakagawa, F.; Tsunogai, U.

    2006-12-01

    The triple oxygen isotopic compositions (18O/16O and 17O/16O) of nitrate in natural waters can be a useful tracer to clarify the sources. The triple oxygen isotopic compositions of nitrate have been usually determined by using conventional IRMS system using O2 molecule converted from nitrate through multiple reaction/purification steps. The traditional methods, however, required at least 1-100 μmol quantities of nitrate so that applications of the methods to various environmental nitrate samples were difficult. Thus, we developed a rapid and sensitive analytical system to determine the triple oxygen isotopic compositions of nitrate in nmol quantities using continuous-flow IRMS (CF-IRMS) without the cumbersome and time-consuming pretreatments. Our method is based on the isotopic analysis of N2O quantitatively converted from nitrate based on the simple reactions using spongy cadmium and sodium azide in an acetic acid buffer. However, we cannot determine 17O/16O ratio of N2O directly by measuring the masses 44, 45, and 46 of N2O introduced to IRMS, because the measured output of mass 45 from IRMS consists of 14N15N16O, 15N14N16O, and 14N14N17O. Thus, addition to the N2O isotopic analysis at the masses 44, 45, and 46, the 15N/14N ratio is determined separately for the same sample N2O. To attain this purpose, two instrumental approaches were done. In the first system, the N2+ fragment ion beams of N2O at masses 28 and 29 were used to determine the 15N/14N ratio of N2O. While the analytical precisions better than 0.5 ‰ for 20 nmol N2O injections and better than 1.0 ‰ for 7 nmol N2O injections were obtained for 15N/14N ratio, we found that the accuracy strongly depended on the quantities introduced. In the second system, the N2 molecules, converted from N2O using an on line Cu reduction furnace (720 degree) was used to determine the 15N/14N ratio of N2O. The analytical precisions better than 0.1 ‰ for 5 nmol N2O injections and better than 0.4 ‰ for 1 nmol N2O

  3. Examining Earthquake Scaling Via Event Ratio Levels

    NASA Astrophysics Data System (ADS)

    Walter, W. R.; Yoo, S.; Mayeda, K. M.; Gok, R.

    2013-12-01

    A challenge with using corner frequency to interpret stress parameter scaling is that stress drop and apparent stress are related to the cube of the corner frequency. In practice this leads to high levels of uncertainty in measured stress from since the uncertainty in measuring the corner frequency is cubed to determine uncertainty in the stress parameters. We develop a new approach using the low and high frequency levels of spectral ratios between two closely located events recorded at the same stations. This approach has a number of advantages over more traditional corner frequency fitting, either in spectral ratios or individual spectra. First, if the bandwidth of the spectral ratio is sufficient, the levels can be measured at many individual frequency points and averaged, reducing the measurement error. Second the apparent stress (and stress drop) are related to the high frequency level to the 3/2 power so the measurement uncertainty is not as amplified as when using the corner frequency. Finally, if the bandwidth is sufficiently broad to determine both the spectral ratio low and high frequency levels, the apparent stress (or stress drop) ratio can be determined without the need to use any other measurements (e.g., moment, fault area), which of course have their own measurement uncertainties. We will show a number examples taken from a wide variety of crustal earthquake sequences. Example of the sigmoid formed by a spectral ratio between two hypothetical events for two different cases of stress scaling using the models described in this paper. Event 1 is Mw 6.0 event and event 2 is an Mw 4.0 event. In the self-similar case both have an apparent stress of 3 MPa, in the non-self-similar case the large event apparent stress is 3 MPA and the smaller one is 1 MPa. Note that ratio reaches different constant levels. The low frequency level (LVL) is the ratio of the moments and high frequency level (HFL) depends on the stress parameters. In this paper we derive the

  4. 2H/(1)H and (13)C/(12)C isotope ratios of trans-anethole using gas chromatography-isotope ratio mass spectrometry.

    PubMed

    Bilke, Steffi; Mosandl, Armin

    2002-07-03

    Authenticity assessment of trans-anethole is deduced from (2)H/(1)H and (13)C/(12)C isotope ratios, determined by gas chromatography-isotope ratio mass spectrometry (GC-IRMS). For that purpose, self-prepared anise and fennel oils, and synthetic and "natural" samples of trans-anethole, as well as commercially available anise and fennel oils have been investigated. Authenticity ranges of (2)H/(1)H and (13)C/(12)C isotope ratios of trans-anethole were defined. Scope and limitations of the applied online GC-IRMS techniques are discussed.

  5. On-site isotopic analysis of dissolved inorganic carbon using an isotope ratio infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Stoltmann, Tim; Mandic, Magda; Stöbener, Nils; Wapelhorst, Eric; Aepfler, Rebecca; Hinrichs, Kai-Uwe; Taubner, Heidi; Jost, Hj; Elvert, Marcus

    2016-04-01

    An Isotope Ratio Infrared Spectrometer (IRIS) has been adapted to perform measurements of δ13C of dissolved inorganic carbon (DIC) in marine pore waters. The resulting prototype allowed highly automated analysis of δ13C isotopic ratios and CO2 concentration. We achieved a throughput of up to 70 samples per day with DIC contents as low as 1.7 μmol C. We achieved an internal precision of 0.066 ‰ and an external precision of 0.16 ‰, which is comparable to values given for Isotope Ratio Mass Spectrometers (IRMS). The prototype instrument is field deployable, suitable for shipboard analysis of deep sea core pore waters. However, the validation of the prototype was centered around a field campaign in Eckernförde Bay, NW- Baltic Sea. As a proof of concept, a shallow site within an area of submarine groundwater discharge (SGD) and a site outside this area was investigated. We present profiles of δ13C of DIC over 50 cm exhibiting well understood methane turnover processes (anaerobic oxidation of methane). At the lowest point below the seafloor, microbial reduction of CO2 to CH4 dominates. 12CO2 is reduced preferentially over 13CO2, leading to more positive δ13C values in the remaining DIC pool; in layers closer to the surface, the oxidation of CH4 to CO2 becomes more prominent. Since the CH4 pool is enriched in 12C a shift to more negative δ13C can be observed in the DIC pool. In the upper 15 cm, the pore water DIC mixes with the sea water DIC, increasing δ13C again. Finally, we will present recent developments to further improve performance and future plans for deployments on research cruises.

  6. On-site isotopic analysis of dissolved inorganic carbon using an isotope ratio infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Jost, H. J. H.; Stoltmann, T.; Stöbener, N.; Wapelhorst, E.; Mandic, M.; Aepfler, R.; Hinrichs, K. U.; Taubner, H.; Elvert, M.

    2015-12-01

    An Isotope Ratio Infrared Spectrometer (IRIS) has been adapted to perform measurements of δ13C of dissolved inorganic carbon (DIC) in marine pore waters. The resulting prototype allowed highly automated analysis of δ13C isotopic ratios and CO2 concentration. We achieved a throughput of up to 70 samples per day with DIC contents as low as 1.7 μmol C. We achieved an internal precision of 0.066 ‰ and an external precision of 0.16 ‰, which is comparable to values given for Isotope Ratio Mass Spectrometers (IRMS). The prototype instrument is field deployable, suitable for shipboard analysis of deep sea core pore waters. However, the validation of the prototype was centered around a field campaign in Eckernförde Bay, NW- Baltic Sea. As a proof of concept, a shallow site within an area of submarine groundwater discharge (SGD) and a site outside this area was investigated. We present profiles of δ13C of DIC over 50 cm exhibiting well understood methane turnover processes (anaerobic oxidation of methane). At the lowest point below the seafloor, microbial reduction of CO2 to CH4 dominates. 12CO2 is reduced preferentially over 13CO2, leading to more positive δ13C values in the remaining DIC pool; in layers closer to the surface, the oxidation of CH4 to CO2 becomes more prominent. Since the CH4 pool is enriched in 12C a shift to more negative δ13C can be observed in the DIC pool. In the upper 15 cm, the pore water DIC mixes with the sea water DIC, increasing δ13C again. Finally, we will present recent developments to further improve performance and future plans for deployments on research cruises.

  7. Carbon, Hydrogen, and Oxygen Isotope Ratios of Cellulose from Plants Having Intermediary Photosynthetic Modes 1

    PubMed Central

    Sternberg, Leonel O'Reilly; Deniro, Michael J.; Ting, Irwin P.

    1984-01-01

    Carbon and hydrogen isotope ratios of cellulose nitrate and oxygen isotope ratios of cellulose from species of greenhouse plants having different photosynthetic modes were determined. When hydrogen isotope ratios are plotted against carbon isotope ratios, four clusters of points are discernible, each representing different photosynthetic modes: C3 plants, C4 plants, CAM plants, and C3 plants that can shift to CAM or show the phenomenon referred to as CAM-cycling. The combination of oxygen and carbon isotope ratios does not distinguish among the different photosynthetic modes. Analysis of the carbon and hydrogen isotope ratios of cellulose nitrate should prove useful for screening different photosynthetic modes in field specimens that grew near one another. This method will be particularly useful for detection of plants which show CAM-cycling. PMID:16663360

  8. Frontiers of QC Laser spectroscopy for high precision isotope ratio analysis of greenhouse gases

    NASA Astrophysics Data System (ADS)

    Emmenegger, Lukas; Mohn, Joachim; Harris, Eliza; Eyer, Simon; Ibraim, Erkan; Tuzson, Béla

    2016-04-01

    An important milestone for laser spectroscopy was achieved when isotope ratios of greenhouse gases were reported at precision levels that allow addressing research questions in environmental sciences. Real-time data with high temporal resolution at moderate cost and instrument size make the optical approach highly attractive, complementary to the well-established isotope-ratio mass-spectrometry (IRMS) method. Especially appealing, in comparison to IRMS, is the inherent specificity to structural isomers having the same molecular mass. Direct absorption in the MIR in single or dual QCL configuration has proven highly reliable for the sta-ble isotopes of CO2, N2O and CH4. The longest time series of real-time measurements is currently available for δ13C and δ18O in CO2 at the high-alpine station Jung-fraujoch. At this well-equipped site, QCL based direct absorption spectroscopy (QCLAS) measurements are ongoing since 2008 1,2. Applications of QCLAS for N2O and CH4 stable isotopes are considerably more challenging because of the lower atmospheric mixing ratios, especially for the less abundant species, such as N218O and CH3D. For high precision (< 0.1 ‰) measurements in ambient air, QCLAS may be combined with a fully automated preconcentration unit yielding an up to 500 times concentration increase and the capability to separate the target gas from spectral interferants by se-quential desorption 3. Here, we review our recent developments on high precision isotope ratio analysis of greenhouse gases, with special focus on the isotopic species of N2O and CH4. Furthermore, we show environ-mental applications illustrating the highly valuable information that isotope ratios of atmospheric trace gases can carry. For example, the intramolecular distribution of 15N in N2O gives important information on the geochemical cycle of N2O4-6, while the analysis of δ13C and δ D in CH4 may be applied to disentangle microbial, fossil and landfill sources 7. 1 Sturm, P., Tuzson, B

  9. Late Miocene evolution of the Black Sea: insights from palynology and strontium isotope ratios

    NASA Astrophysics Data System (ADS)

    Grothe, Arjen; van Baak, Christiaan; Vasiliev, Iuliana; Sangiorgi, Francesca; Reichart, Gert-Jan; Stoica, Marius; Krijgsman, Wout

    2016-04-01

    During the late Miocene, the connection(s) between the Mediterranean Basin and the Atlantic Ocean deteriorated, which ultimately culminated in thick evaporite deposits and a water level drop in the Mediterranean Basin during the so-called Messinian Salinity Crisis (MSC, 5.97 - 5.33 Ma). It has been claimed that Black Sea, in response to the MSC, also desiccated but these claims have been proven incorrectly. Here we present palynological (dinoflagellate cysts and pollen) and strontium isotope ratios from two Black Sea records: the Zheleznyi Rog outcrop section and Deep Sea Drilling Project Hole 380A. Organic walled cyst-producing dinoflagellates are highly sensitive to even small changes in surface waters and strontium isotope ratios are excellent recorders of changing connectivity. Our records provide therefore more insights in the sensitivity of the Black Sea to Messinian Salinity Crisis and the general evolution of the late Miocene Black Sea.

  10. Maintaining high precision of isotope ratio analysis over extended periods of time.

    PubMed

    Brand, Willi A

    2009-06-01

    Stable isotope ratios are reliable and long lasting process tracers. In order to compare data from different locations or different sampling times at a high level of precision, a measurement strategy must include reliable traceability to an international stable isotope scale via a reference material (RM). Since these international RMs are available in low quantities only, we have developed our own analysis schemes involving laboratory working RM. In addition, quality assurance RMs are used to control the long-term performance of the delta-value assignments. The analysis schemes allow the construction of quality assurance performance charts over years of operation. In this contribution, the performance of three typical techniques established in IsoLab at the MPI-BGC in Jena is discussed. The techniques are (1) isotope ratio mass spectrometry with an elemental analyser for delta(15)N and delta(13)C analysis of bulk (organic) material, (2) high precision delta(13)C and delta(18)O analysis of CO(2) in clean-air samples, and (3) stable isotope analysis of water samples using a high-temperature reaction with carbon. In addition, reference strategies on a laser ablation system for high spatial resolution delta(13)C analysis in tree rings is exemplified briefly.

  11. Forensic applications of isotope ratio mass spectrometry--a review.

    PubMed

    Benson, Sarah; Lennard, Chris; Maynard, Philip; Roux, Claude

    2006-02-10

    The key role of a forensic scientist is to assist in determining whether a crime has been committed, and if so, assist in the identification of the offender. Many people hold the belief that a particular item can be conclusively linked to a specific person, place or object. Unfortunately, this is often not achievable in forensic science. In performing their role, scientists develop and test hypotheses. The significance of those hypotheses that cannot be rejected upon completion of all available examinations/analyses is then evaluated. Although one can generally identify the substances present using available techniques, it is generally not possible to distinguish one source of the same substance from another. In such circumstances, although a particular hypothesis cannot be rejected, it cannot be conclusively proven, i.e. the samples could still have originated from different sources. This limitation of not being able to distinguish between sources currently extends to the analysis of other forensic samples including, but not limited to, ignitable liquids, paints, adhesives, textile fibres, plastics, and illicit drugs. Stable isotope ratio mass spectrometry (IRMS) is an additional technique that can be utilised to test a given hypothesis. This technique shows the potential to be able to individualise a range of materials of forensic interest. This paper provides a brief description of the technique, followed by a review of the various applications of IRMS in different scientific fields. The focus of this summary is on forensic applications of IRMS, in particular the analysis of explosives, ignitable liquids and illicit drugs.

  12. Effects of carbonate leaching on foraminifer stable isotopes ratios

    NASA Astrophysics Data System (ADS)

    Obrochta, S.; Yokoyama, Y.; Sakai, S.; Ishimura, T.

    2011-12-01

    Stable carbon and oxygen isotope ratios were measured on 125 individual epifaunal and infaunal benthic foraminifers from two discrete Holocene intervals in a shallow-water sediment core (~ 450 m) from the Timor Sea. Methane seeps are common in the area, resulting in significant precipitation of secondary calcite that is confirmed by SEM photomicrographs and has likely resulted in inconsistent downcore results. To assess the degree of removal of contaminants, individual Uvigerina peregrina were subjected to varying degrees of pretreatment prior to analysis. All foraminifers received standard cleaning with ethanol and brief sonication. A subset were further cleaned and sonicated in a dilute HCl solution (~ 0.003 M). Foraminifer tests were photographed using both reflected light and scanning electron microscopes during the course of treatment to monitor the changing degree of contaminant removal as increasingly aggressive cleaning methods were employed. Visible contamination remained on individuals not subjected to HCl treatment. The leached individuals exhibit a lower overall relative standard deviation and consistent results within morphotype groups. Based on these results, a 2% value is expected to be typical of the Holocene, though further downcore analyses are pending restoration of equipment adversely effected by the Eastern Japan 3/11 earthquake.

  13. Environmental controls on stable isotope ratios in New Zealand Podocarpaceae: Implications for palaeoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Brett, Marianne J.; Baldini, James U. L.; Gröcke, Darren R.

    2014-09-01

    Stable isotope ratios of various proxies are widely used for palaeoclimate reconstruction, and it is often assumed that isotope ratios reflect vegetation abundance or type. However, very little research exists on the isotopic equilibration of extant biomes under variable environmental conditions. In this study, carbon and oxygen isotope ratios from leaves of various Podocarpaceae genera, endemic to New Zealand, are linked to environmental parameters from the Land Environments New Zealand model. The dominant influence on stable isotope ratios within the majority of Podocarpaceae studied here is vapour pressure deficit (VPD). A simple latitudinal trend does not exist, and neither temperature nor rainfall (decoupled from VPD) controls the stable isotope ratios. The results suggest that modern spatial heterogeneity in VPD affects the stable isotope values of vegetation, and that historic VPD variability would change the stable isotope ratios of Podocarpaceae without necessitating a change in vegetation type, density, or productivity. This represents an alternative model for temporal isotope change within geochemical proxies and reinforces the need for increased stable isotopic research in modern plant ecosystems to better understand modern, and eventually palaeoclimatic processes affecting the terrestrial biosphere.

  14. Stable carbon and oxygen isotopic analysis of atmospheric carbon monoxide using continuous-flow isotope ratio MS by isotope ratio monitoring of CO.

    PubMed

    Tsunogai, Urumu; Nakagawa, Fumiko; Komatsu, Daisuke D; Gamo, Toshitaka

    2002-11-15

    We have developed a rapid and simple measurement system for both content and stable isotopic compositions (13C and 18O) of atmospheric CO, using continuous-flow isotope ratio mass spectrometry by simultaneously monitoring the CO+ ion currents at masses 28, 29, and 30. The analytical system consisted sequentially of a sample trapping port (liquid nitrogen temperature silica gel and molecular sieve 5A), a gas dryer, a CO purification column (molecular sieve 5A), a cryofocusing unit, and a final purification column using a GC capillary. Analytical precision of 0.2 per thousand for 13C and 0.4 per thousand for 18O can be realized for samples that contain as little as 300 pmol of CO within 40 min for one sample analysis. Analytical blanks associated with the method are less than 1 pmol. The extent of analytical error in delta13C due to mass-independent fractionation of oxygen in natural CO is estimated to be less than 0.3 per thousand. Based on this system, we report herein a kinetic isotopic effect during CO consumption in soil.

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

    PubMed

    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

  16. Heterogeneity of Mg Isotopes and Variable ^26Al/^27Al Ratio in FUN CAIs

    NASA Astrophysics Data System (ADS)

    Park, C.; Nagashima, K.; Hutcheon, I. D.; Wasserburg, G. J.; Papanastassiou, D. A.; Davis, A. M.; Huss, G. R.; Krot, A. N.

    2013-09-01

    We report high-precision Mg-isotope data of individual minerals from the Axtell 2271, BG82DH8, EK1-4-1, C1, TE, and CG14 FUN CAIs, which shows variations in both Mg-isotope ratio and ^26Al/^27Al ratio.

  17. Spatial and Temporal Trends in Stable Carbon and Oxygen Isotope Ratios of Juvenile Winter Flounder

    EPA Science Inventory

    Isotopic ratios of fish otoliths have been used in numerous studies as natural tags or markers to aid the study of connectivity among fish populations. We investigated the use of spatial and temporal changes in the stable carbon and oxygen isotope ratios of otoliths to different...

  18. Forensic Applications of Light-Element Stable Isotope Ratios of Ricinus communis Seeds and Ricin Preparations

    SciTech Connect

    Kreuzer, Helen W.; West, Jason B.; Ehleringer, James

    2013-01-01

    Seeds of the castor plant Ricinus communis, also known as castor beans, are of forensic interest because they are the source of the poison ricin. We have tested whether stable isotope ratios of castor seeds and ricin prepared by various methods can be used as a forensic signature. We collected over 300 castor seed samples from locations around the world and measured the C, N, O, and H stable isotope ratios of the whole seeds, oil, and three types of ricin preparations. Our results demonstrate that N isotope ratios can be used to correlate ricin prepared by any of these methods to source seeds. Further, stable isotope ratios distinguished >99% of crude and purified ricin protein samples in pair-wise comparison tests. Stable isotope ratios therefore constitute a valuable forensic signature for ricin preparations.

  19. MS fragment isotope ratio analysis for evaluation of citrus essential oils by HRGC-MS.

    PubMed

    Satake, Atsushi; Furukawa, Kiyoshi; Ueno, Takao; Ukeda, Hiroyuki; Sawamura, Masayoshi

    2004-02-01

    To evaluate the origin of citrus essential oils, the isotope ratio of fragment peaks on HRGC-MS of the volatile compounds from various citrus oils was measured. The MS fragment ratio was found by the ratio of fragment peak intensity, m+1/m (m/z). This ratio reflects the isotope effect of volatile compounds, that is, it provides information about locality, quality, and species for essential oils. Multivariate analysis based on the MS fragment ratio of monoterpene hydrocarbons clearly distinguished three citrus species, yuzu, lemon, and lime. The carbonyl fractions were also extracted from citrus essential oils by the sodium hydrogensulfite method. The isotope ratio of MS fragments of octanal, nonanal, and decanal was also examined. The results suggest that there was no significant difference in the individual fragment isotope ratios of the three aldehydes.

  20. Stable isotope ratio determination of the origin of vanillin in vanilla extracts and its relationship to vanillin/potassium ratios

    SciTech Connect

    Martin, G.E.; Alfonso, F.C.; Figert, D.M.; Burggraff, J.M.

    1981-09-01

    A method is described for isolating vanillin from vanilla extract, followed by stable isotope ratio analysis to determine the amount of natural vanillin contained in adulterated vanilla extracts. After the potassium content is determined, the percent Madagascar and/or Java vanilla beans incorporated into the extract may then be approximated from the vanillin/potassium ratio.

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

    SciTech Connect

    Bolivar, J. P.; Olias, M.; Gonzalez-Garcia, F.; Garcia-Tenorio, R.

    2008-08-07

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

  2. Zn/Cd ratios and cadmium isotope evidence for the classification of lead-zinc deposits

    PubMed Central

    Wen, Hanjie; Zhu, Chuanwei; Zhang, Yuxu; Cloquet, Christophe; Fan, Haifeng; Fu, Shaohong

    2016-01-01

    Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ114/110Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ114/110Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits. PMID:27121538

  3. Zn/Cd ratios and cadmium isotope evidence for the classification of lead-zinc deposits.

    PubMed

    Wen, Hanjie; Zhu, Chuanwei; Zhang, Yuxu; Cloquet, Christophe; Fan, Haifeng; Fu, Shaohong

    2016-04-28

    Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ(114/110)Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ(114/110)Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits.

  4. Zn/Cd ratios and cadmium isotope evidence for the classification of lead-zinc deposits

    NASA Astrophysics Data System (ADS)

    Wen, Hanjie; Zhu, Chuanwei; Zhang, Yuxu; Cloquet, Christophe; Fan, Haifeng; Fu, Shaohong

    2016-04-01

    Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ114/110Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ114/110Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits.

  5. Equations for Lipid Normalization of Carbon Stable Isotope Ratios in Aquatic Bird Eggs

    PubMed Central

    Elliott, Kyle H.; Davis, Mikaela; Elliott, John E.

    2014-01-01

    Stable isotope ratios are biogeochemical tracers that can be used to determine the source of nutrients and contaminants in avian eggs. However, the interpretation of stable carbon ratios in lipid-rich eggs is complicated because 13C is depleted in lipids. Variation in 13C abundance can therefore be obscured by variation in percent lipids. Past attempts to establish an algebraic equation to correct carbon isotope ratios for lipid content in eggs have been unsuccessful, possibly because they relied partly on data from coastal or migratory species that may obtain egg lipids from different habitats than egg protein. We measured carbon, nitrogen and sulphur stable isotope ratios in 175 eggs from eight species of aquatic birds. Carbon, nitrogen and sulphur isotopes were enriched in lipid-extracted egg samples compared with non extracted egg samples. A logarithmic equation using the C∶N ratio and carbon isotope ratio from the non extracted egg tissue calculated 90% of the lipid-extracted carbon isotope ratios within ±0.5‰. Calculating separate equations for eggs laid by species in different habitats (pelagic, offshore and terrestrial-influenced) improved the fit. A logarithmic equation, rather than a linear equation as often used for muscle, was necessary to accurately correct for lipid content because the relatively high lipid content of eggs compared with muscle meant that a linear relationship did not accurately approximate the relationship between percent lipids and the C∶N ratio. Because lipid extraction alters sulphur and nitrogen isotope ratios (and cannot be corrected algebraically), we suggest that isotopic measurement on bulk tissue followed by algebraic lipid normalization of carbon stable isotope ratio is often a good solution for homogenated eggs, at least when it is not possible to complete separate chemical analyses for each isotope. PMID:24465384

  6. Simulating Stable Isotope Ratios in Plumes of Groundwater Pollutants with BIOSCREEN-AT-ISO.

    PubMed

    Höhener, Patrick; Li, Zhi M; Julien, Maxime; Nun, Pierrick; Robins, Richard J; Remaud, Gérald S

    2017-03-01

    BIOSCREEN is a well-known simple tool for evaluating the transport of dissolved contaminants in groundwater, ideal for rapid screening and teaching. This work extends the BIOSCREEN model for the calculation of stable isotope ratios in contaminants. A three-dimensional exact solution of the reactive transport from a patch source, accounting for fractionation by first-order decay and/or sorption, is used. The results match those from a previously published isotope model but are much simpler to obtain. Two different isotopes may be computed, and dual isotope plots can be viewed. The dual isotope assessment is a rapidly emerging new approach for identifying process mechanisms in aquifers. Furthermore, deviations of isotope ratios at specific reactive positions with respect to "bulk" ratios in the whole compound can be simulated. This model is named BIOSCREEN-AT-ISO and will be downloadable from the journal homepage.

  7. Guidelines and recommended terms for expression of stable-isotope-ratio and gas-ratio measurement results

    USGS Publications Warehouse

    Coplen, Tyler B.

    2011-01-01

    To minimize confusion in the expression of measurement results of stable isotope and gas-ratio measurements, recommendations based on publications of the Commission on Isotopic Abundances and Atomic Weights of the International Union of Pure and Applied Chemistry (IUPAC) are presented. Whenever feasible, entries are consistent with the Système International d'Unités, the SI (known in English as the International System of Units), and the third edition of the International Vocabulary of Basic and General Terms in Metrology (VIM, 3rd edition). The recommendations presented herein are approved by the Commission on Isotopic Abundances and Atomic Weights and are designed to clarify expression of quantities related to measurement of isotope and gas ratios to ensure that quantity equations instead of numerical value equations are used for quantity definitions. Examples of column headings consistent with quantity calculus (also called the algebra of quantities) and examples of various deprecated usages connected with the terms recommended are presented.

  8. Relationship between carbon and nitrogen isotope ratios for lower trophic ecosystem in marine environments

    NASA Astrophysics Data System (ADS)

    Aita, M. N.; Ishii, R.; Tadokoro, K.; Smith, S. L.; Wada, E.

    2012-12-01

    To examine the relationship between carbon and nitrogen stable isotope ratios (δ13C and δ15N) along food chains, we analyzed using the data from the Oyashio waters at the western North Pacific (samples collected from March to October 2009), the warm-core ring 86-B derived from the Kuroshio extension region (preserved samples), and previously published data from the Gulf of Alaska and Antarctic Ocean. The statistical analysis suggested a common slope of δ15N versus δ13C (Δδ15N/Δδ13C) among regions. We attribute this similarity to common physiological aspects of feeding processes (e.g., kinetic isotope effects inherent in the processes of amino acid synthesis). We also compared seasonal differences seasonal in Δδ15N/Δδ13C for the euphotic layers of the Oyashio waters. The Δδ15N/Δδ13C slope of the food chain during the spring bloom differs from its common value in other seasons. If we could better understand both carbon and nitrogen trophic fractionation within ecosystems, the stable isotope ratios may help to elucidate migratory behavior of higher trophic levels such as fishes in marine ecosystems as well as frame work of biogeochemical cycles in question.

  9. The isotope systematics of a juvenile intraplate volcano: Pb, Nd, and Sr isotope ratios of basalts from Loihi Seamount, Hawaii

    USGS Publications Warehouse

    Staudigel, H.; Zindler, A.; Hart, S.R.; Leslie, T.; Chen, C.-Y.; Clague, D.

    1984-01-01

    Sr, Nd, and Pb isotope ratios for a representative suite of 15 basanites, alkali basalts, transitional basalts and tholeiites from Loihi Seamount, Hawaii, display unusually large variations for a single volcano, but lie within known ranges for Hawaiian basalts. Nd isotope ratios in alkali basalts show the largest relative variation (0.51291-0.51305), and include the nearly constant tholeiite value ( ??? 0.51297). Pb isotope ratios show similarly large ranges for tholeiites and alkali basalts and continue Tatsumoto's [31] "Loa" trend towards higher 206Pb 204Pb ratios, resulting in a substantial overlap with the "Kea" trend. 206Pb 204Pb ratios for Loihi and other volcanoes along the Loa and Kea trends [31] are observed to correlate with the age of the underlying lithosphere suggesting lithosphere involvement in the formation of Hawaiian tholeiites. Loihi lavas display no correlation of Nd, Sr, or Pb isotope ratios with major element compositions or eruptive age, in contrast with observations of some other Hawaiian volcanoes [38]. Isotope data for Loihi, as well as average values for Hawaiian volcanoes, are not adequately explained by previously proposed two-end-member models; new models for the origin and the development of Hawaiian volcanoes must include mixing of at least three geochemically distinct source regions and allow for the involvement of heterogeneous oceanic lithosphere. ?? 1984.

  10. The IRHUM (Isotopic Reconstruction of Human Migration) database - bioavailable strontium isotope ratios for geochemical fingerprinting in France

    NASA Astrophysics Data System (ADS)

    Willmes, M.; McMorrow, L.; Kinsley, L.; Armstrong, R.; Aubert, M.; Eggins, S.; Falguères, C.; Maureille, B.; Moffat, I.; Grün, R.

    2014-03-01

    Strontium isotope ratios (87Sr / 86Sr) are a key geochemical tracer used in a wide range of fields including archaeology, ecology, food and forensic sciences. These applications are based on the principle that the Sr isotopic ratios of natural materials reflect the sources of strontium available during their formation. A major constraint for current studies is the lack of robust reference maps to evaluate the source of strontium isotope ratios measured in the samples. Here we provide a new data set of bioavailable Sr isotope ratios for the major geologic units of France, based on plant and soil samples (Pangaea data repository doi:10.1594/PANGAEA.819142). The IRHUM (Isotopic Reconstruction of Human Migration) database is a web platform to access, explore and map our data set. The database provides the spatial context and metadata for each sample, allowing the user to evaluate the suitability of the sample for their specific study. In addition, it allows users to upload and share their own data sets and data products, which will enhance collaboration across the different research fields. This article describes the sampling and analytical methods used to generate the data set and how to use and access the data set through the IRHUM database. Any interpretation of the isotope data set is outside the scope of this publication.

  11. The IRHUM (Isotopic Reconstruction of Human Migration) database - bioavailable strontium isotope ratios for geochemical fingerprinting in France

    NASA Astrophysics Data System (ADS)

    Willmes, M.; McMorrow, L.; Kinsley, L.; Armstrong, R.; Aubert, M.; Eggins, S.; Falguères, C.; Maureille, B.; Moffat, I.; Grün, R.

    2013-11-01

    Strontium isotope ratios (87Sr/86Sr) are a key geochemical tracer used in a wide range of fields including archaeology, ecology, food and forensic sciences. These applications are based on the principle that the Sr isotopic ratios of natural materials reflect the sources of strontium available during their formation. A major constraint for current studies is the lack of robust reference maps to evaluate the source of strontium isotope ratios measured in the samples. Here we provide a new dataset of bioavailable Sr isotope ratios for the major geologic units of France, based on plant and soil samples (Pangaea data repository doi:10.1594/PANGAEA.819142). The IRHUM (Isotopic Reconstruction of Human Migration) database is a web platform to access, explore and map our dataset. The database provides the spatial context and metadata for each sample, allowing the user to evaluate the suitability of the sample for their specific study. In addition, it allows users to upload and share their own datasets and data products, which will enhance collaboration across the different research fields. This article describes the sampling and analytical methods used to generate the dataset and how to use and access of the dataset through the IRHUM database. Any interpretation of the isotope dataset is outside the scope of this publication.

  12. GUM Analysis for SIMS Isotopic Ratios in BEP0 Graphite Qualification Samples, Round 2

    SciTech Connect

    Gerlach, David C.; Heasler, Patrick G.; Reid, Bruce D.

    2009-01-01

    This report describes GUM calculations for TIMS and SIMS isotopic ratio measurements of reactor graphite samples. These isotopic ratios are used to estimate reactor burn-up, and currently consist of various ratios of U, Pu, and Boron impurities in the graphite samples. The GUM calculation is a propagation of error methodology that assigns uncertainties (in the form of standard error and confidence bound) to the final estimates.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  14. Biometrics from the carbon isotope ratio analysis of amino acids in human hair.

    PubMed

    Jackson, Glen P; An, Yan; Konstantynova, Kateryna I; Rashaid, Ayat H B

    2015-01-01

    This study compares and contrasts the ability to classify individuals into different grouping factors through either bulk isotope ratio analysis or amino-acid-specific isotope ratio analysis of human hair. Using LC-IRMS, we measured the isotope ratios of 14 amino acids in hair proteins independently, and leucine/isoleucine as a co-eluting pair, to provide 15 variables for classification. Multivariate analysis confirmed that the essential amino acids and non-essential amino acids were mostly independent variables in the classification rules, thereby enabling the separation of dietary factors of isotope intake from intrinsic or phenotypic factors of isotope fractionation. Multivariate analysis revealed at least two potential sources of non-dietary factors influencing the carbon isotope ratio values of the amino acids in human hair: body mass index (BMI) and age. These results provide evidence that compound-specific isotope ratio analysis has the potential to go beyond region-of-origin or geospatial movements of individuals-obtainable through bulk isotope measurements-to the provision of physical and characteristic traits about the individuals, such as age and BMI. Further development and refinement, for example to genetic, metabolic, disease and hormonal factors could ultimately be of great assistance in forensic and clinical casework.

  15. Strontium isotope ratios and the origin of anorthosites

    SciTech Connect

    Vinogradov, V.I.

    1986-01-01

    Anorthosites are rocks consisting almost completely of calcic plagioclase, usually from andesine to labradorite. They are not widespread, and until recently were of no economic interest. However, with the advance of the new global tectonics, which has excited considerable interest in the structure and composition of upper-mantle rocks, interest in the anorthosites has grown. This has particularly been the case since the discovery of anorthosites on the moon, where they appear to be more widespread than on the earth. Data have recently been obtained on the strontium isotope compositions of anorthosite intrusions in the Dzhugdzhur-Stanovoy zone and in the rocks surrounding them, which have revealed some unexpected features. The paper describes the geological features of anorthosites, initial concepts on strontium isotope geochemistry, strontium isotope compositions of this region, and discusses some genetic consequences from the isotope data. Although the data of this study are insufficient to determine the origin of anorthosites, the data indicate several points which should be considered in following studies. 11 references, 1 figure.

  16. Using Stable Isotope Ratio Analysis to Distinguish Perchlorate Sources

    DTIC Science & Technology

    2011-03-30

    Desert - natural nitrogen fertilizer 2. Mineral deposits – Death Valley, CA 3. Southwest soils and groundwater B. Other Anthropogenic 1. Fireworks 2...Herbicides Gunpowder Fireworks Road Flares Taiwanese Natural (Chile)  3 7 C l ( p e r m i l ) 18O (per mil) Forensic Isotopic Analysis: Chilean vs

  17. Improved isotope ratio measurement performance in liquid chromatography/isotope ratio mass spectrometry by removing excess oxygen.

    PubMed

    Hettmann, Elena; Brand, Willi A; Gleixner, Gerd

    2007-01-01

    A low dead volume oxygen scrubbing system was introduced in a commercially available liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) interface to enhance the analytical capability of the system. In the LC/IRMS interface carbon from organic samples is converted into CO(2) inside the mobile phase by wet chemical oxidation using peroxodisulfate (Na(2)S(2)O(8)). After passing the hot reaction zone, surplus oxygen (O(2)) remains dissolved in the liquid phase. Both CO(2) and O(2) diffuse through a transfer membrane into the helium carrier and are transferred to the mass spectrometer. The presence of O(2) in the ion source may have detrimental effects on measurement accuracy and precision as well as on filament lifetime. As a remedy, a new on-line O(2)-removing device has been incorporated into the system. The new O(2) scrubber consists of two parallel hot copper reduction reactors (0.8 mm i.d., active length 120 mm) and a switch-over valve between them. One reactor is regenerated using He/H(2) while the other is actively scavenging O(2) from the gas stream. The capacity of each reduction reactor, expressed as usage time, is between 40 and 50 min. This is sufficient for a single LC run for sugars and organic acids. A further increase of the reduction capacity is accompanied by a peak broadening of about 100%. After switching to a freshly reduced reactor the oxygen background and the delta(13)C values of the reference gas need up to 500 s to stabilize. For repeated injections the delta(13)C values of sucrose remain constant (+/-0.1 per thousand) for about 3000 s. The long-term stability for measurements of sucrose was 0.11 per thousand without the reduction oven and improved slightly to 0.08 per thousand with the reduction oven. The filament lifetime improved by more than 600%, thereby improving the long-term system stability and analytical efficiency. In addition the costs per analysis were reduced considerably.

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

    NASA Astrophysics Data System (ADS)

    Kluge, Tobias; Haderlein, Astrid; Weißbach, Therese

    2016-04-01

    Oxygen isotope ratios in speleothems (notably stalagmites) have been used since decades to successfully infer paleotemperatures and deduce paleo-environmental information. In addition, recent technical developments allow to increasingly use fluid inclusions as an archive for drip-water and together with the surrounding calcite as paleothermometer. A basic requirement for isotope data interpretation is the complete knowledge of the fractionation between calcite and fluid. Most laboratory and in-situ cave experiments focus on calcite growth and the isotope fractionation between calcite and feed solution. Potential isotope exchange and re-equilibration processes after the initial deposition have mostly been neglected. However, experiments of Oelkers et al. (2015) showed that the isotope exchange between minerals and fluid can proceed rapidly (within days), even at chemical equilibrium. In hydrous Mg carbonates a similar process of continuous isotope exchange between carbonate and fluid was observed after the carbonate precipitation was completed (Mavromatis et al., 2015). These observations suggest that the isotope ratios of speleothem calcite may be affected by this continuous exchange, likely driving the isotope composition continuously towards equilibrium at the respective cave conditions. In addition, fluid inclusions are suspected to be sensitive to an isotope exchange with the surrounding carbonate highlighting the need to precisely understand and quantify this effect. We assessed the oxygen isotope exchange between calcite and solution at chemical equilibrium conditions with theoretical estimates and laboratory experiments over an intermediate time scale (hours-weeks). A large isotope gradient (~20 ‰)) between solution and calcite was prepared in the experiment to investigate the dynamics of this re-equilibration process. We used a theoretical model based on a Rayleigh fractionation approach and the direct comparison with the experiment to determine

  19. USE OF THE COMPOSITION AND STABLE CARBON ISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (Gamma 13C) of individual microbial phospholipid fatty acids (PLFAS) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SO...

  20. Uranium and Calcium Isotope Ratio Measurements using the Modified Total Evaporation Method in TIMS

    NASA Astrophysics Data System (ADS)

    Richter, S.; Kuehn, H.; Berglund, M.; Hennessy, C.

    2010-12-01

    A new version of the "modified total evaporation" (MTE) method for isotopic analysis by multi-collector thermal ionization mass spectrometry (TIMS), with high analytical performance and designed in a more user-friendly and routinely applicable way, is described in detail. It is mainly being used for nuclear safeguards measurements of U and Pu and nuclear metrology, but can readily be applied to other scientific tasks in geochemistry, e.g. for Sr, Nd and Ca, as well. The development of the MTE method was organized in collaboration of several "key nuclear mass spectrometry laboratories", namely the New Brunswick Laboratory (NBL), the Institute for Transuranium Elements (ITU), the Safeguards Analytical Laboratory (now Safeguards Analytical Services, SGAS) of the International Atomic Energy Agency (IAEA) and the Institute for Reference Materials and Measurements (IRMM), with IRMM taking the leading role. The manufacturer of the TRITON TIMS instrument, Thermo Fisher Scientific, integrated this method into the software of the instrument. The development has now reached its goal to become a user-friendly and routinely useable method for uranium isotope ratio measurements with high precision and accuracy. Due to the use of the “total evaporation” (TE) method the measurement of the "major" uranium isotope ratio 235U/238U is routinely being performed with a precision of 0.01% to 0.02%. The use of a (certified) reference material measured under comparable conditions is emphasized to achieve an accuracy at a level of 0.02% - depending on the stated uncertainty of the certified value of the reference material. In contrast to the total evaporation method (TE), in the MTE method the total evaporation sequence is interrupted on a regular basis to allow for correction for background from peak tailing, internal calibration of a secondary electron multiplier (SEM) detector versus the Faraday cups, and ion source re-focusing. Therefore, the most significant improvement using the

  1. Tracing lead pollution sources in abandoned mine areas using stable Pb isotope ratios.

    PubMed

    Yoo, Eun-Jin; Lee, Jung-A; Park, Jae-Seon; Lee, Khanghyun; Lee, Won-Seok; Han, Jin-Seok; Choi, Jong-Woo

    2014-02-01

    This study focused on Pb isotope ratios of sediments in areas around an abandoned mine to determine if the ratios can be used as a source tracer. For pretreatment, sediment samples were dissolved with mixed acids, and a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS, Nu plasma II) was used to investigate the Pb isotopic composition of the samples. The measured isotope ratios were then corrected for instrumental mass fractionation by measuring the (203)Tl/(205)Tl ratio. Repeated measurements with the NIST SRM 981 reference material showed that the precision of all ratios was below 104 ppm (±2σ) for 50 ng/g. The isotope ratios ((207)Pb/(206)Pb) found were 0.85073 ± 0.0004~0.85373 ± 0.0003 for the main stream, while they were 0.83736 ± 0.0010 for the tributary and 0.84393 ± 0.0002 for the confluence. A binary mixing equation for isotope ratios showed that the contributions of mine lead to neighboring areas were up to 60%. Therefore, Pb isotope ratios can be a good source tracer for areas around abandoned mines.

  2. Stable carbon isotope ratios of toluene in the boundary layer and the lower free troposphere

    NASA Astrophysics Data System (ADS)

    Wintel, J.; Hösen, E.; Koppmann, R.; Krebsbach, M.; Hofzumahaus, A.; Rohrer, F.

    2013-11-01

    During the field campaign ZEPTER-2 in autumn 2008 whole air samples were collected on board a Zeppelin NT airship in the planetary boundary layer (PBL) and the lower free troposphere (LFT) over south-west Germany using the ZEppelin Based Isotope Sampler (ZEBIS). These samples were analysed with respect to volatile organic compound (VOC) mixing ratios and stable carbon isotope ratios using a gas chromatograph combustion isotope ratio mass spectrometer (GC-C-IRMS). In this study we present results for toluene, one of the major anthropogenic pollutants, which emphasise the viability of isotope ratio measurements in VOC for atmospheric research, especially to study VOC sources or to track both dynamical and chemical processes. In situ measurements of CO mixing ratios on board the Zeppelin NT were used to allocate the air samples either to the PBL or the LFT. In the PBL we observed rather fresh emissions mixing into the background air. We estimated a toluene source isotope ratio of δ13C = -28.2 ± 0.5‰. Samples from the PBL and the LFT were clearly distinguishable by means of their mixing ratio and isotope ratio signatures. Using the concept of the effective kinetic isotope effect, we were able to separate the effects of dilution processes and photochemical degradation in the free troposphere. We calculated the photochemical age of toluene in the atmosphere in two different ways using isotope ratios and mixing ratios. The results differ strongly in the PBL, probably due to mixing processes, but are compatible with each other in the LFT. Here, they correlate with a slope of 0.90±0.31.

  3. Lead isotope ratios for bullets, forensic evaluation in a Bayesian paradigm.

    PubMed

    Sjåstad, Knut-Endre; Lucy, David; Andersen, Tom

    2016-01-01

    Forensic science is a discipline concerned with collection, examination and evaluation of physical evidence related to criminal cases. The results from the activities of the forensic scientist may ultimately be presented to the court in such a way that the triers of fact understand the implications of the data. Forensic science has been, and still is, driven by development of new technology, and in the last two decades evaluation of evidence based on logical reasoning and Bayesian statistic has reached some level of general acceptance within the forensic community. Tracing of lead fragments of unknown origin to a given source of ammunition is a task that might be of interest for the Court. Use of data from lead isotope ratios analysis interpreted within a Bayesian framework has shown to be suitable method to guide the Court to draw their conclusion for such task. In this work we have used isotopic composition of lead from small arms projectiles (cal. .22) and developed an approach based on Bayesian statistics and likelihood ratio calculation. The likelihood ratio is a single quantity that provides a measure of the value of evidence that can be used in the deliberation of the court.

  4. Selenium isotope ratios as indicators of selenium sources and oxyanion reduction

    USGS Publications Warehouse

    Johnson, T.M.; Herbel, M.J.; Bullen, T.D.; Zawislanski, P.T.

    1999-01-01

    Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. We report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Accordingly, Se isotope ratios should be useful as indicators of oxyanion reduction, which can transform mobile species to forms that are less mobile and less bioavailable. Additional investigations of Se isotope fractionation are needed to confirm this preliminary assessment. We have developed a new method for measurement of natural Se isotope ratio variation which requires less than 500 ng Se per analysis and yields ??0.2??? precision on 80Se/76Se. A double isotope spike technique corrects for isotopic fractionation during sample preparation and mass spectrometry. The small minimum sample size is important, as Se concentrations are often below 1 ppm in solids and 1 ??g/L in fluids. The Se purification process is rapid and compatible with various sample matrices, including acidic rock or sediment digests.

  5. A new isotopic reference material for stable hydrogen and oxygen isotope-ratio measurements of water—USGS50 Lake Kyoga Water

    USGS Publications Warehouse

    Coplen, Tyler B.; Wassenaar, Leonard I; Mukwaya, Christine; Qi, Haiping; Lorenz, Jennifer M.

    2015-01-01

    This isotopic reference material, designated as USGS50, is intended as one of two reference waters for daily normalization of stable hydrogen and oxygen isotopic analysis of water with an isotope-ratio mass spectrometer or a laser absorption spectrometer, of use especially for isotope-hydrology laboratories analyzing freshwater samples from equatorial and tropical regions.

  6. Methods and limitations of 'clumped' CO2 isotope (Delta47) analysis by gas-source isotope ratio mass spectrometry.

    PubMed

    Huntington, K W; Eiler, J M; Affek, H P; Guo, W; Bonifacie, M; Yeung, L Y; Thiagarajan, N; Passey, B; Tripati, A; Daëron, M; Came, R

    2009-09-01

    The geochemistry of multiply substituted isotopologues ('clumped-isotope' geochemistry) examines the abundances in natural materials of molecules, formula units or moieties that contain more than one rare isotope (e.g. (13)C(18)O(16)O, (18)O(18)O, (15)N(2), (13)C(18)O(16)O(2) (2-)). Such species form the basis of carbonate clumped-isotope thermometry and undergo distinctive fractionations during a variety of natural processes, but initial reports have provided few details of their analysis. In this study, we present detailed data and arguments regarding the theoretical and practical limits of precision, methods of standardization, instrument linearity and related issues for clumped-isotope analysis by dual-inlet gas-source isotope ratio mass spectrometry (IRMS). We demonstrate long-term stability and subtenth per mil precision in 47/44 ratios for counting systems consisting of a Faraday cup registered through a 10(12) ohm resistor on three Thermo-Finnigan 253 IRMS systems. Based on the analyses of heated CO(2) gases, which have a stochastic distribution of isotopes among possible isotopologues, we document and correct for (1) isotopic exchange among analyte CO(2) molecules and (2) subtle nonlinearity in the relationship between actual and measured 47/44 ratios. External precisions of approximately 0.01 per thousand are routinely achieved for measurements of the mass-47 anomaly (a measure mostly of the abundance anomaly of (13)C-(18)O bonds) and follow counting statistics. The present technical limit to precision intrinsic to our methods and instrumentation is approximately 5 parts per million (ppm), whereas precisions of measurements of heterogeneous natural materials are more typically approximately 10 ppm (both 1 s.e.). These correspond to errors in carbonate clumped-isotope thermometry of +/-1.2 degrees C and +/-2.4 degrees C, respectively.

  7. Multi-collector Isotope Ratio Mass Spectrometer -- Operational Performance Report

    SciTech Connect

    Appelhans, Anthony D; Olson, John E; Watrous, Matthew G; Ward, Michael B.; Dahl, David A.

    2010-12-01

    This report describes the operational testing of a new magnetic sector mass spectrometer that utilizes seven full-sized discrete dynode electron multipliers operating simultaneously. The instrument includes a newly developed ion dispersion lens that enables the mass dispersed individual isotope beams to be separated sufficiently to allow a full-sized discrete dynode pulse counting multiplier to be used to measure each isotope beam. The performance of the instrument was measured using SRM 996 (244Pu spike) at loadings of 2.4 and 12 fg on resin beads and with SRM 4350B Columbia River Sediment samples. The measured limit of detection (3s) for 240Pu was 3.4 attograms for SRM 996. The limit of quantitation (LOQ), defined as 10 s, was 11.2 attograms. The measured concentration of 239Pu in the CRS standard was 152 ± 6 fg/g.

  8. Factors controlling precision and accuracy in isotope-ratio-monitoring mass spectrometry

    NASA Technical Reports Server (NTRS)

    Merritt, D. A.; Hayes, J. M.

    1994-01-01

    The performance of systems in which picomole quantities of sample are mixed with a carrier gas and passed through an isotope-ratio mass spectrometer system was examined experimentally and theoretically. Two different mass spectrometers were used, both having electron-impact ion sources and Faraday cup collector systems. One had an accelerating potential of 10kV and accepted 0.2 mL of He/min, producing, under those conditions, a maximum efficiency of 1 CO2 molecular ion collected per 700 molecules introduced. Comparable figures for the second instrument were 3 kV, 0.5 mL of He/min, and 14000 molecules/ion. Signal pathways were adjusted so that response times were <200 ms. Sample-related ion currents appeared as peaks with widths of 3-30 s. Isotope ratios were determined by comparison to signals produced by standard gases. In spite of rapid variations in signals, observed levels of performance were within a factor of 2 of shot-noise limits. For the 10-kV instrument, sample requirements for standard deviations of 0.1 and 0.5% were 45 and 1.7 pmol, respectively. Comparable requirements for the 3-kV instrument were 900 and 36 pmol. Drifts in instrumental characteristics were adequately neutralized when standards were observed at 20-min intervals. For the 10-kV instrument, computed isotopic compositions were independent of sample size and signal strength over the ranges examined. Nonlinearities of <0.04%/V were observed for the 3-kV system. Procedures for observation and subtraction of background ion currents were examined experimentally and theoretically. For sample/ background ratios varying from >10 to 0.3, precision is expected and observed to decrease approximately 2-fold and to depend only weakly on the precision with which background ion currents have been measured.

  9. Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.

    SciTech Connect

    Keck, B D; Ognibene, T; Vogel, J S

    2010-02-05

    Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of any separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30 fg

  10. Stable carbon isotope ratios of toluene in the boundary layer and the lower free troposphere

    NASA Astrophysics Data System (ADS)

    Wintel, J.; Hösen, E.; Koppmann, R.; Krebsbach, M.

    2013-04-01

    Measurements of stable carbon isotope ratios in VOC are a powerful tool to identify sources or to track both dynamical and chemical processes. During the field campaign ZEPTER-2 in autumn 2008 whole air samples were collected on board a Zeppelin NT airship in the planetary boundary layer and the lower free troposphere over south-west Germany. These samples were analysed with respect to VOC mixing ratios and stable carbon isotope ratios using a gas chromatograph combustion isotope ratio mass spectrometer. In this study we present the results for toluene, one of the major anthropogenic pollutants. In the boundary layer we observed rather fresh emissions mixing into the background and derived a toluene source isotope ratio of δ13C = -28.2 ± 0.5 ‰. Using the concept of the effective kinetic isotope effect, we were able to separate the effects of dilution processes and photochemical degradation in the free troposphere. We estimated the photochemical age of toluene in the atmosphere in two different ways (using isotope ratios and mixing ratios, respectively). The results differ strongly in the planetary boundary layer, probably due to mixing processes, but are compatible with each other in the free troposphere.

  11. Historical variations of mercury stable isotope ratios in Arctic glacier firn and ice cores

    NASA Astrophysics Data System (ADS)

    Zdanowicz, C. M.; Krümmel, E. M.; Poulain, A. J.; Yumvihoze, E.; Chen, J.; Å trok, M.; Scheer, M.; Hintelmann, H.

    2016-09-01

    The concentration and isotopic composition of mercury (Hg) were determined in glacier core samples from Canadian Arctic ice caps dating from preindustrial to recent time (early 21st century). Mean Hg levels increased from ≤ 0.2 ng L-1 in preindustrial time to ~0.8-1.2 ng L-1 in the modern industrial era (last ~200 years). Hg accumulated on Arctic ice caps has Δ199Hg and Δ201Hg that are higher (~ -1 to 2.9‰) than previously reported for Arctic snow impacted by atmospheric Hg depletion events (mostly < -1‰), suggesting that these events contribute little to Hg accumulation on ice caps. The range of δ202Hg, Δ199Hg, and Δ201Hg in glacier cores overlaps with that of Arctic Hg0(g) and of seawater in Baffin Bay and also with that of midlatitude precipitation and industrial Hg sources, including coal and Hg ores. A core from Agassiz ice cap (80.7°N) shows a ~ +1‰ shift in δ202Hg over the nineteenth to twentieth centuries that could reflect changes in the isotopic composition of the atmospheric Hg pool in the High Arctic in response to growing industrial emissions at lower latitudes. This study is the first ever to report on historical variations of Hg stable isotope ratios in Arctic ice cores. Results could help constrain future modeling efforts of the global Hg biogeochemical cycle and the atmosphere's response to changing Hg emissions, past and future.

  12. Longitudinal profiling of urinary steroids by gas chromatography/combustion/isotope ratio mass spectrometry: diet change may result in carbon isotopic variations.

    PubMed

    Saudan, Christophe; Kamber, Matthias; Barbati, Giulia; Robinson, Neil; Desmarchelier, Aurélien; Mangin, Patrice; Saugy, Martial

    2006-02-02

    Longitudinal profiling of urinary steroids was investigated by using a gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) method. The carbon isotope ratio of three urinary testosterone (T) metabolites: androsterone, etiocholanolone, 5beta-androstane-3alpha,17beta-diol (5beta-androstanediol) together with 16(5alpha)-androsten-3alpha-ol (androstenol) and 5beta-pregnane-3alpha,20alpha-diol (5beta-pregnanediol) were measured in urine samples collected from three top-level athletes over 2 years. Throughout the study, the subjects were living in Switzerland and were residing every year for a month or two in an African country. (13)C-enrichment larger than 2.5 per thousand was observed for one subject after a 2-month stay in Africa. Our findings reveal that (13)C-enrichment caused by a diet change might be reduced if the stay in Africa was shorter or if the urine sample was not collected within the days after return to Switzerland. The steroids of interest in each sample did not show significant isotopic fractionation that could lead to false positive results in anti-doping testing. In contrast to the results obtained with the carbon isotopic ratio, profiling of urinary testosterone/epitestosterone (T/E) ratios was found to be unaffected by a diet change.

  13. Temporal trends in nitrogen isotope ratios of winter flounder collected from Rhode Island coastal systems

    EPA Science Inventory

    Nitrogen isotope ratios (15N) were measured in muscle tissue of juvenile winter flounder, Pseudopleuronectes americanus, collected from several estuarine systems along the coast of Rhode Island, USA, including Narragansett Bay, Narrow River and three coastal lagoons. Fish collect...

  14. The identification of lead ammunition as a source of lead exposure in First Nations: the use of lead isotope ratios.

    PubMed

    Tsuji, Leonard J S; Wainman, Bruce C; Martin, Ian D; Sutherland, Celine; Weber, Jean-Philippe; Dumas, Pierre; Nieboer, Evert

    2008-04-15

    The use of lead shotshell to hunt water birds has been associated with lead-contamination in game meat. However, evidence illustrating that lead shotshell is a source of lead exposure in subsistence hunting groups cannot be deemed definitive. This study seeks to determine whether lead shotshell constitutes a source of lead exposure using lead isotope ratios. We examined stable lead isotope ratios for lichens, lead shotshell and bullets, and blood from residents of Fort Albany and Kashechewan First Nations, and the City of Hamilton, Ontario, Canada. Data were analyzed using ANOVA and regression analyses. ANOVA of isotope ratios for blood revealed significant differences with respect to location, but not sex. Hamilton differed from both Kashechewan and Fort Albany; however, the First Nations did not differ from each other. ANOVA of the isotope ratios for lead ammunition and lichens revealed no significant differences between lichen groups (north and south) and for the lead ammunition sources (pellets and bullets). A plot of (206)Pb/(204)Pb and (206)Pb/(207)Pb values illustrated that lichens and lead ammunition were distinct groupings and only the 95% confidence ellipse of the First Nations group overlapped that of lead ammunition. In addition, partial correlations between blood-lead levels (adjusted for age) and isotope ratios revealed significant (p<0.05) positive correlations for (206)Pb/(204)Pb and (206)Pb/(207)Pb, and a significant negative correlation for (208)Pb/(206)Pb, as predicted if leaded ammunition were the source of lead exposure. In conclusion, lead ammunition was identified as a source of lead exposure for First Nations people; however, the isotope ratios for lead shotshell pellets and bullets were indistinguishable. Thus, lead-contaminated meat from game harvested with lead bullets may also be contributing to the lead body burden.

  15. High precision determination of bromine isotope ratio by GC-MC-ICPMS

    NASA Astrophysics Data System (ADS)

    Gelman, Faina; Halicz, Ludwik

    2010-01-01

    This work presents a new methodology for the precise determination of bromine isotope ratio in individual organic compounds based on the simultaneous introduction of brominated organic compounds and strontium as an external spike into MC-ICPMS. Using the proposed methodology, an external precision (2[sigma]) up to 0.1[per mille sign] has been attained. The new approach for the bromine isotope ratio analysis could be applied for the investigating the fate of the organobromine compounds in the environment.

  16. Isolation of strontium pools and isotope ratios in modern human hair.

    PubMed

    Tipple, Brett J; Chau, Thuan; Chesson, Lesley A; Fernandez, Diego P; Ehleringer, James R

    2013-10-10

    The elements of human hair record specific information about an individual's health, diet, and surrounding environment. Strontium isotope ratios of human hair have attracted interest as they potentially record an individual's environment. Yet, separating the external environmental signals from the internal dietary indicators has remained a challenge. Here, we examined the effects of five different hair-cleaning methodologies to determine the extent that internal and external strontium signals can be isolated from human hair. In the first study of its kind, we employed an in-line strontium purification methodology and a multi-collector inductively coupled plasma mass spectrometer to obtain high-precision strontium isotope ratio of human hair and of leachates of the different washing treatments. We found that the different applications of an individual treatment removed a consistent amount of strontium from hair and that replicate analyses showed each treatment altered the strontium isotope ratios of hair consistently. A mass-balance approach was applied to demonstrate that strontium was quantitatively removed and was accounted for in either the treated hair or the leachate. We observed that strontium isotope ratio varied as a function of treatment aggressiveness so as to suggest that there was a fine-scale structuring of strontium within hair (transverse cross-sectional variations); these variations existed as differences in strontium concentrations and isotope ratios. As a result, the Sr isotope ratio of hair and hair leachates treated with the most aggressive cleaning methods reflected the isotope ratios of the interior and total exterior strontium signatures, respectively. The results of this study indicate that external environmental strontium signals can be distinguished from the internal signals and therefore permit the application of strontium isotope ratios of modern human hair for geospatial applications.

  17. Accuracy of delta 18O isotope ratio measurements on the same sample by continuous-flow isotope-ratio mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The doubly labeled water method is considered the reference method to measure energy expenditure. Conventional mass spectrometry requires a separate aliquot of the same sample to be prepared and analyzed separately. With continuous-flow isotope-ratio mass spectrometry, the same sample could be analy...

  18. Implications of the Nitrogen Isotope Ratio in Titan's Atmosphere for the Nitrogen Ratio in Ammonia in Comets

    NASA Astrophysics Data System (ADS)

    Mandt, K.; Mousis, O.

    2013-12-01

    The D/H ratio of water measured in solar system bodies has been established as a tool for determining the conditions under which bodies such as comets or icy moons formed. This ratio varies significantly and indicates complex thermal and chemical evolution of the solar nebula during solar system and planetary formation. Nitrogen isotope ratios also vary significantly, and in some but not all cases correlate to D/H ratios, but are poorly understood. Nitrogen in the solar nebula was primarily in the form of atomic and molecular nitrogen. The isotope ratio (14N/15N) of this reservoir is expected to be ~435 based on the ratio measured in Jupiter's atmosphere, because the atmosphere of Jupiter is made up of gas captured from the solar nebula (Owen et al., 2001). The terrestrial atmospheric ratio is 272, which is close to the ratio measured in the Earth's mantle. This may be the primordial ratio for nitrogen delivered to Earth depending on the amount of exchange between the atmosphere and the mantle and any atmospheric fractionation processes that may have influenced the ratio over time. Comets are a possible source of nitrogen in the Earth's atmosphere (Hutsmekers et al., 2009), although chondrites have also been suggested as a source (Marty, 2012). In the case of comets, nitrogen would have been essentially retained in the form of ammonia (Mousis et al., 2012), which is the most abundant form of nitrogen in comets. The nitrogen in Titan's atmosphere is expected to have originated as ammonia hydrates and converted to N2 early in Titan's history (Atreya et al., 1978). The nitrogen ratio in Titan's atmosphere is ~170, which is significantly enriched in the heavy isotope compared to the terrestrial value. We will discuss the evolution of the nitrogen ratio in Titan's atmosphere (Mandt et al., 2009), the limits of the primordial ratio in ammonia, and the implications for this ratio for the isotope ratio in ammonia in comets that should be measured by the ROSINA instrument

  19. Measurement of labile Cu in soil using stable isotope dilution and isotope ratio analysis by ICP-MS.

    PubMed

    Nolan, Annette L; Ma, Yibing; Lombi, Enzo; McLaughlin, Mike J

    2004-11-01

    Isotope dilution is a useful technique to measure the labile metal pool, which is the amount of metal in soil in rapid equilibrium (<7 days) with the soil solution. This is normally performed by equilibrating soil with a metal isotope, and sampling the labile metal pool by using an extraction (E value), or by growing plants (L value). For Cu, this procedure is problematic for E values, and impossible for L values, due to the short half-life of the 64Cu radioisotope (12.4 h), which makes access and handling very difficult. We therefore developed a technique using enriched 65Cu stable isotope and measurement of 63Cu/65Cu ratios by quadrupole inductively coupled plasma mass spectrometry (ICP-MS) to measure labile pools of Cu in soils using E value techniques. Mass spectral interferences in detection of 63Cu/65Cu ratios in soil extracts were found to be minimal. Isotope ratios determined by quadrupole ICP-MS compared well to those determined by high-resolution (magnetic sector) ICP-MS. E values determined using the stable isotope technique compared well to those determined using the radioisotope for both uncontaminated and Cu-contaminated soils.

  20. Stable Carbon and Nitrogen Isotope Ratios of Sodium and Potassium Cyanide as a Forensic Signature

    SciTech Connect

    Kruzer, Helen W; Horita, Juske; Moran, James J; Tomkins, Bruce A; Janszen, Derek B; Carman, April

    2012-01-01

    Sodium and potassium cyanide are highly toxic, produced in large amounts by the chemical industry, and linked to numerous high-profile crimes. The U.S. Centers for Disease Control and Prevention has identified cyanide as one of the most probable agents to be used in a future chemical terrorism event. We investigated whether stable C and N isotopic content of sodium and potassium cyanide could serve as a forensic signature for sample matching, using a collection of 65 cyanide samples. A few of these samples displayed non-homogeneous isotopic content associated with degradation to a carbonate salt and loss of hydrogen cyanide. Most samples had highly reproducible isotope content. Of these, >95% could be properly matched based on C and N isotope ratios, with a false match rate <3%. These results suggest that stable C and N isotope ratios are a useful forensic signature for matching cyanide samples.

  1. Stable Carbon and Nitrogen Isotope Ratios of Sodium and Potassium Cyanide as a Forensic Signature

    SciTech Connect

    Kreuzer, Helen W.; Horita, Juske; Moran, James J.; Tomkins, Bruce; Janszen, Derek B.; Carman, April J.

    2012-01-03

    Sodium and potassium cyanide are highly toxic, produced in large amounts by the chemical industry, and linked to numerous high-profile crimes. The U.S. Centers for Disease Control and Prevention has identified cyanide as one of the most probable agents to be used in a future chemical terrorism event. We investigated whether stable C and N isotopic content of sodium and potassium cyanide could serve as a forensic signature for sample matching, using a collection of 65 cyanide samples. A few of these samples displayed non-homogeneous isotopic content associated with degradation to a carbonate salt and loss of hydrogen cyanide. Most samples had highly reproducible isotope content. Of these, >95% could be properly matched based on C and N isotope ratios, with a false match rate <3%. These results suggest that stable C and N isotope ratios are a useful forensic signature for matching cyanide samples.

  2. Mare basalt genesis - Modeling trace elements and isotopic ratios

    NASA Technical Reports Server (NTRS)

    Binder, A. B.

    1985-01-01

    Various types of mare basalt data have been synthesized, leading to the production of an internally consistent model of the mare basalt source region and mare basalt genesis. The model accounts for the mineralogical, major oxide, compatible siderophile trace element, incompatible trace element, and isotopic characteristics of most of the mare basalt units and of all the pyroclastic glass units for which reliable data are available. Initial tests of the model show that it also reproduces the mineralogy and incompatible trace element characteristics of the complementary highland anorthosite suite of rocks and, in a general way, those of the lunar granite suite of rocks.

  3. Intracellular metabolite levels shape sulfur isotope fractionation during microbial sulfate respiration

    PubMed Central

    Wing, Boswell A.; Halevy, Itay

    2014-01-01

    We present a quantitative model for sulfur isotope fractionation accompanying bacterial and archaeal dissimilatory sulfate respiration. By incorporating independently available biochemical data, the model can reproduce a large number of recent experimental fractionation measurements with only three free parameters: (i) the sulfur isotope selectivity of sulfate uptake into the cytoplasm, (ii) the ratio of reduced to oxidized electron carriers supporting the respiration pathway, and (iii) the ratio of in vitro to in vivo levels of respiratory enzyme activity. Fractionation is influenced by all steps in the dissimilatory pathway, which means that environmental sulfate and sulfide levels control sulfur isotope fractionation through the proximate influence of intracellular metabolites. Although sulfur isotope fractionation is a phenotypic trait that appears to be strain specific, we show that it converges on near-thermodynamic behavior, even at micromolar sulfate levels, as long as intracellular sulfate reduction rates are low enough (<<1 fmol H2S⋅cell−1⋅d−1). PMID:25362045

  4. Intracellular metabolite levels shape sulfur isotope fractionation during microbial sulfate respiration

    NASA Astrophysics Data System (ADS)

    Wing, Boswell A.; Halevy, Itay

    2014-12-01

    We present a quantitative model for sulfur isotope fractionation accompanying bacterial and archaeal dissimilatory sulfate respiration. By incorporating independently available biochemical data, the model can reproduce a large number of recent experimental fractionation measurements with only three free parameters: (i) the sulfur isotope selectivity of sulfate uptake into the cytoplasm, (ii) the ratio of reduced to oxidized electron carriers supporting the respiration pathway, and (iii) the ratio of in vitro to in vivo levels of respiratory enzyme activity. Fractionation is influenced by all steps in the dissimilatory pathway, which means that environmental sulfate and sulfide levels control sulfur isotope fractionation through the proximate influence of intracellular metabolites. Although sulfur isotope fractionation is a phenotypic trait that appears to be strain specific, we show that it converges on near-thermodynamic behavior, even at micromolar sulfate levels, as long as intracellular sulfate reduction rates are low enough (<<1 fmol H2Sṡcell-1ṡd-1).

  5. Intracellular metabolite levels shape sulfur isotope fractionation during microbial sulfate respiration.

    PubMed

    Wing, Boswell A; Halevy, Itay

    2014-12-23

    We present a quantitative model for sulfur isotope fractionation accompanying bacterial and archaeal dissimilatory sulfate respiration. By incorporating independently available biochemical data, the model can reproduce a large number of recent experimental fractionation measurements with only three free parameters: (i) the sulfur isotope selectivity of sulfate uptake into the cytoplasm, (ii) the ratio of reduced to oxidized electron carriers supporting the respiration pathway, and (iii) the ratio of in vitro to in vivo levels of respiratory enzyme activity. Fractionation is influenced by all steps in the dissimilatory pathway, which means that environmental sulfate and sulfide levels control sulfur isotope fractionation through the proximate influence of intracellular metabolites. Although sulfur isotope fractionation is a phenotypic trait that appears to be strain specific, we show that it converges on near-thermodynamic behavior, even at micromolar sulfate levels, as long as intracellular sulfate reduction rates are low enough (<1 fmol H2S⋅cell(-1)⋅d(-1)).

  6. Bayesian Integration of Isotope Ratios for Geographic Sourcing of Castor Beans

    SciTech Connect

    Webb-Robertson, Bobbie-Jo M.; Kreuzer, Helen W.; Hart, Garret L.; Ehleringer, James; West, Jason B.; Gill, Gary A.; Duckworth, Douglas C.

    2012-08-15

    Recent years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based on the integrated model with a class accuracy of 6 0 . 9 {+-} 2 . 1 % versus 5 5 . 9 {+-} 2 . 1 % and 4 0 . 2 {+-} 1 . 8 % for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model.

  7. Isotope ratio analysis by HRGC-MS of monoterpene hydrocarbons from citrus essential oils.

    PubMed

    Satake, Atsushi; Une, Akitoshi; Ueno, Takao; Ukeda, Hiroyuki; Sawamura, Masayoshi

    2003-03-01

    The isotope ratio of monoterpene hydrocarbons in citrus essential oils of different origins was measured by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). The isotope ratio (Ir) was determined by the ratio of the isotope peak intensity (m/z 137) to the molecular mass peak intensity (m/z 136) of the monoterpene hydrocarbons. The accuracy of Ir was examined by measuring monoterpene hydrocarbon standards and 13C-labeled compounds. The isotope fingerprints based on the values of monoterpene hydrocarbons from lemon, lime and yuzu essential oils were determined. These citrus essential oils were also discriminated by a principal component analysis of their Ir data. The characteristic vectors showed that alpha-terpinene, beta-pinene and beta-phellandrene were important components for distinguishing between the citrus species. It is suggested that this technique will be applicable to evaluate the quality, genuineness and origin of citrus fruits and their products.

  8. Are sulfur isotope ratios sufficient to determine the antiquity of sulfate reduction. [implications for chemical evolution

    NASA Technical Reports Server (NTRS)

    Ashendorf, D.

    1980-01-01

    Possible limitations on the use of sulfur isotope ratios in sedimentary sulfides to infer the evolution of microbial sulfate reduction are discussed. Current knowledge of the ways in which stable sulfur isotope ratios are altered by chemical and biological processes is examined, with attention given to the marine sulfur cycle involving various microbial populations, and sulfur reduction processes, and it is noted that satisfactory explanations of sulfur isotope ratios observed in live organisms and in sediments are not yet available. It is furthermore pointed out that all members of the same genus of sulfate reducing bacteria do not always fractionate sulfur to the same extent, that the extent of sulfur fractionation by many sulfate-reducing organisms has not yet been determined, and that inorganic processes can also affect sulfur isotope fractionation values. The information currently available is thus concluded to be insufficient to determine the time of initial appearance of biological sulfate reduction.

  9. Do Strontium Isotope Ratios of Animal Bone and Teeth Really Reflect the Isotope Ratios of its birth- and growth-places?

    NASA Astrophysics Data System (ADS)

    Minami, M.; Goto, A.; Suzuki, K.; Kato, T.; Watanabe, K.; Hasegawa, T.

    2007-12-01

    Strontium enters the human body through the food chain as nutrients pass from bedrock through soil and water to plants and animals. Strontium substitutes for calcium in the hydroxyapatite mineral of skeletal tissue, and is stored there. 87Sr/86Sr ratios in an individual's bone and teeth could directly reflect the isotopic ratios found in the plants and animals that she or he consumed, which reflect the isotope ratios found in the soil and bedrock of that geologic region. Therefore, 87Sr/86Sr ratios of human skeletons could be useful tools for assessing human residential mobility in prehistory, and many studies on them have been often made. In this study, to evaluate whether the 87Sr/86Sr ratio of a bone or teeth really reflects the isotopic ratios of its birth and growth places, several bone and teeth samples were measured for 87Sr/86Sr ratios, compared with 87Sr/86Sr ratios of geological samples in their growth-places. Bone and teeth samples were leached with 5% acetic acid. After drying, samples were ashed in a muffle furnace at 825°C for 8h, and then digested in nitric acid, followed by cation exchange chromatography with 2.4M hydrochloric acid. 87Sr/86Sr ratios were measured using a thermal ionization mass Spectrometer (VG Sector 54) or an inductively coupled plasma mass spectrometer (Finnigan ELEMENT2). A modern boar bone collected at Asuke, Toyota City, Aichi prefecture, Japan showed a 87Sr/86Sr of 0.71001±0.00002 (2 σ), while stream sediments in the Asuke area showed around 0.710 (Asahara et al., 2006). The 87Sr/86Sr ratio of a modern black bass bone collected from Lake Biwa, Shiga prefecture, Japan was 0.71215±0.00002, while those of surface water in Lake Biwa was 0.71233±0.00002. The similar 87Sr/86Sr ratios between bone and its provenance geology could indicate that the 87Sr/86Sr ratios of bones reflect the isotopic ratios of the birth- and growth-places. The more results of modern and fossil skeletons will be shown in our presentation.

  10. Evaluation of the 34S/32S ratio of Soufre de Lacq elemental sulfur isotopic reference material by continuous flow isotope-ratio mass spectrometry

    USGS Publications Warehouse

    Qi, H.P.; Coplen, T.B.

    2003-01-01

    Soufre de Lacq elemental sulfur reference material (IAEA-S-4) isotopically is homogeneous in amounts as small as 41 ??g as determined by continuous flow isotope-ratio mass spectrometry. The ??34S value for this reference material is +16.90 ?? 0.12??? (1??) on a scale (Vienna Can??on Diablo troilite, VCDT) where IAEA-S-1 Ag2S is -0.3??? and IAEA-S-2 Ag2S is +22.67???. Published by Elsevier Science B.V.

  11. Application of lead and strontium isotope ratio measurements for the origin assessment of uranium ore concentrates.

    PubMed

    Varga, Zsolt; Wallenius, Maria; Mayer, Klaus; Keegan, Elizabeth; Millet, Sylvain

    2009-10-15

    Lead and strontium isotope ratios were used for the origin assessment of uranium ore concentrates (yellow cakes) for nuclear forensic purposes. A simple and low-background sample preparation method was developed for the simultaneous separation of the analytes followed by the measurement of the isotope ratios by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The lead isotopic composition of the ore concentrates suggests applicability for the verification of the source of the nuclear material and by the use of the radiogenic (207)Pb/(206)Pb ratio the age of the raw ore material can be calculated. However, during data interpretation, the relatively high variation of the lead isotopic composition within the mine site and the generally high contribution of natural lead as technological contamination have to be carefully taken into account. The (87)Sr/(86)Sr isotope ratio is less prone to the variation within one mine site and less affected by the production process, thus it was found to be a more purposeful indicator for the origin assessment and source verification than the lead. The lead and strontium isotope ratios measured and the methodology developed provide information on the initial raw uranium ore used, and thus they can be used for source attribution of the uranium ore concentrates.

  12. Investigating controls on boron isotope ratios in shallow marine carbonates

    NASA Astrophysics Data System (ADS)

    Zhang, Shuang; Henehan, Michael J.; Hull, Pincelli M.; Reid, R. Pamela; Hardisty, Dalton S.; Hood, Ashleigh v. S.; Planavsky, Noah J.

    2017-01-01

    The boron isotope-pH proxy has been widely used to reconstruct past ocean pH values. In both planktic foraminifera and corals, species-specific calibrations are required in order to reconstruct absolute values of pH, due to the prevalence of so-called vital effects - physiological modification of the primary environmental signals by the calcifying organisms. Shallow marine abiotic carbonate (e.g. ooids and cements) could conceivably avoid any such calibration requirement, and therefore provide a potentially useful archive for reconstructions in deep (pre-Cenozoic) time. However, shallow marine abiotic carbonates could also be affected by local shifts in pH caused by microbial photosynthesis and respiration, something that has up to now not been fully tested. In this study, we present boron isotope measurements from shallow modern marine carbonates, from the Bahama Bank and Belize to investigate the potential of using shallow water carbonates as pH archives, and to explore the role of microbial processes in driving nominally 'abiogenic' carbonate deposition. For Bahama bank samples, our boron-based pH estimates derived from a range of carbonate types (i.e. ooids, peloids, hardground cements, carbonate mud, stromatolitic micrite and calcified filament micrite) are higher than the estimated modern mean-annual seawater pH values for this region. Furthermore, the majority (73%) of our marine carbonate-based pH estimates fall out of the range of the estimated pre-industrial seawater pH values for this region. In shallow sediment cores, we did not observe a correlation between measured pore water pH and boron-derived pH estimates, suggesting boron isotope variability is a depositional rather than early diagenetic signal. For Belize reef cements, conversely, the pH estimates are lower than likely in situ seawater pH at the time of cement formation. This study indicates the potential for complications when using shallow marine non-skeletal carbonates as marine pH archives

  13. Atmospheric helium isotope ratio: Possible temporal and spatial variations

    NASA Astrophysics Data System (ADS)

    Sano, Yuji; Furukawa, Yukiko; Takahata, Naoto

    2010-09-01

    The atmospheric 3He/ 4He ratio has been considered to be constant on a global scale, because the residence time of helium is significantly longer than the mixing time in the atmosphere. However, this ratio may be decreasing with time owing to the anthropogenic release of crustal helium from oil and natural gas wells, although this observation has been disputed. Here, we present the 3He/ 4He ratios of old air trapped in historical slags in Japan and of modern surface air samples collected at various sites around the world, measured with a newly developed analytical system. In air helium extracted from metallurgical slag found at refineries in operation between AD 1603 and 1907 in Japan, we determined a mean 3He/ 4He ratio of (5106 ± 108) × 10 -5 R HESJ (where R HESJ is the 3He/ 4He ratio of the Helium Standard of Japan), which is consistent with the previously reported value of (5077 ± 59) × 10 -5 R HESJ for historical slags in France and United Arab Emirates and about 4% higher than that of average modern air, (4901 ± 4) × 10 -5 R HESJ. This result implies that the air 3He/ 4He ratio has decreased with time as expected by anthropogenic causes. Our modern surface air samples revealed that the 3He/ 4He ratio increases from north to south at a rate of (0.16 ± 0.08) × 10 -5 R HESJ/degree of latitude, suggesting that the low 3He/ 4He ratio originates in high-latitude regions of the northern hemisphere, which is consistent with the fact that most fossil fuel is extracted and consumed in the northern hemisphere.

  14. Hydrogen and Oxygen Isotope Ratios in Body Water and Hair: Modeling Isotope Dynamics in Nonhuman Primates

    PubMed Central

    O’Grady, Shannon P.; Valenzuela, Luciano O.; Remien, Christopher H.; Enright, Lindsey E.; Jorgensen, Matthew J.; Kaplan, Jay R.; Wagner, Janice D.; Cerling, Thure E.; Ehleringer, James R.

    2012-01-01

    The stable isotopic composition of drinking water, diet, and atmospheric oxygen influence the isotopic composition of body water (2H/1H, 18O/16O expressed as δ2H and δ18O). In turn, body water influences the isotopic composition of organic matter in tissues, such as hair and teeth, which are often used to reconstruct historical dietary and movement patterns of animals and humans. Here, we used a nonhuman primate system (Macaca fascicularis) to test the robustness of two different mechanistic stable isotope models: a model to predict the δ2H and δ18O values of body water and a second model to predict the δ2H and δ18O values of hair. In contrast to previous human-based studies, use of nonhuman primates fed controlled diets allowed us to further constrain model parameter values and evaluate model predictions. Both models reliably predicted the δ2H and δ18O values of body water and of hair. Moreover, the isotope data allowed us to better quantify values for two critical variables in the models: the δ2H and δ18O values of gut water and the 18O isotope fractionation associated with a carbonyl oxygen-water interaction in the gut (αow). Our modeling efforts indicated that better predictions for body water and hair isotope values were achieved by making the isotopic composition of gut water approached that of body water. Additionally, the value of αow was 1.0164, in close agreement with the only other previously measured observation (microbial spore cell walls), suggesting robustness of this fractionation factor across different biological systems. PMID:22553163

  15. Hydrogen and oxygen isotope ratios in body water and hair: modeling isotope dynamics in nonhuman primates.

    PubMed

    O'Grady, Shannon P; Valenzuela, Luciano O; Remien, Christopher H; Enright, Lindsey E; Jorgensen, Matthew J; Kaplan, Jay R; Wagner, Janice D; Cerling, Thure E; Ehleringer, James R

    2012-07-01

    The stable isotopic composition of drinking water, diet, and atmospheric oxygen influence the isotopic composition of body water ((2)H/(1)H, (18)O/(16)O expressed as δ(2) H and δ(18)O). In turn, body water influences the isotopic composition of organic matter in tissues, such as hair and teeth, which are often used to reconstruct historical dietary and movement patterns of animals and humans. Here, we used a nonhuman primate system (Macaca fascicularis) to test the robustness of two different mechanistic stable isotope models: a model to predict the δ(2)H and δ(18)O values of body water and a second model to predict the δ(2)H and δ(18)O values of hair. In contrast to previous human-based studies, use of nonhuman primates fed controlled diets allowed us to further constrain model parameter values and evaluate model predictions. Both models reliably predicted the δ(2)H and δ(18)O values of body water and of hair. Moreover, the isotope data allowed us to better quantify values for two critical variables in the models: the δ(2)H and δ(18)O values of gut water and the (18)O isotope fractionation associated with a carbonyl oxygen-water interaction in the gut (α(ow)). Our modeling efforts indicated that better predictions for body water and hair isotope values were achieved by making the isotopic composition of gut water approached that of body water. Additionally, the value of α(ow) was 1.0164, in close agreement with the only other previously measured observation (microbial spore cell walls), suggesting robustness of this fractionation factor across different biological systems.

  16. D/H Isotope Ratio Measurements of Atmospheric Volatile Organic Compounds

    NASA Astrophysics Data System (ADS)

    Meisehen, Thomas; Bühler, Fred; Koppmann, Ralf; Krebsbach, Marc

    2015-04-01

    Analysis of isotope ratios in atmospheric volatile organic compounds (VOC) is a reliable method to allocate their sources, to estimate atmospheric residence times and investigate physical and chemical processes on various temporal and spatial scales. Most investigations yet focus on carbon isotope ratios. Certainly more detailed information can be gained by the ratio of deuterium (D) to hydrogen (H) in VOC, especially due to the high mass ratio. Combining measurements of carbon and hydrogen isotopes could lead to considerable improvement in our understanding of atmospheric processes. For this purpose we set up and thoroughly characterised a gas chromatograph pyrolysis isotope ratio mass spectrometer to measure the D/H ratio in atmospheric VOC. From a custom-made gas standard mixture VOC were adsorbed on Tenax®TA which has the advantage that CO2 is not preconcentrated when measuring ambient air samples. Our results show that the pyrolysis method has significant impact on the D/H ratios. A pyrolysis temperature of at least 1723 K and conditioning of the ceramic tube on a regular basis is essential to obtain reproducible D/H isotope ratios. For an independent comparison D/H ratios of the pure VOC used in the gas standard were determined using elemental analysis by Agroisolab (Jülich, Germany). Comparisons of 10 VOC show perfect agreement within the standard deviations of our measurements and the errors given by Agroisolab, e.g. for n-pentane, toluene, 4-methyl-2-pentanone and n-octane. A slight mean difference of 5.1 o was obtained for n-heptane while significant mean differences of 15.5 o and 20.3 o arose for 1,2,4-trimethylbenzene and isoprene, respectively. We further demonstrate the stability of our system and show that the sample preparation does not affect the isotope ratios. Moreover the applicability of our system to ambient air samples is demonstrated.

  17. Seven Channel Multi-collector Isotope Ratio Mass Spectrometer

    SciTech Connect

    Anthony D. Appelhans

    2008-07-01

    A new magnetic sector mass spectrometer that utilizes seven full-sized discrete dynode electron multipliers operating simultaneously has been designed, constructed and is in preliminary testing. The instrument utilizes a newly developed ion dispersion lens that enables the mass dispersed individual isotope beams to be separated sufficiently (35 mm) to allow a full-sized discrete dynode pulse counting multiplier to be used for each beam. The ion dispersion lens is a two element electrostatic 90 degree sector device that causes the beam-to-beam dispersion to increase faster than the intra-beam dispersion. Each multiplier is contained in an isolated case with a deflector/condenser lens at the entrance. A 9-sample filament cartridge is mounted on a micro-manipulator two-axis stage that enables adjustment of the filament position with 10 micron resolution within the ion lens. Results of initial testing with actinides will be presented.

  18. Hydrogen and oxygen isotope ratios in human hair are related to geography

    PubMed Central

    Ehleringer, James R.; Bowen, Gabriel J.; Chesson, Lesley A.; West, Adam G.; Podlesak, David W.; Cerling, Thure E.

    2008-01-01

    We develop and test a model to predict the geographic region-of-origin of humans based on the stable isotope composition of their scalp hair. This model incorporates exchangeable and nonexchangeable hydrogen and oxygen atoms in amino acids to predict the δ2H and δ18O values of scalp hair (primarily keratin). We evaluated model predictions with stable isotope analyses of human hair from 65 cities across the United States. The model, which predicts hair isotopic composition as a function of drinking water, bulk diet, and dietary protein isotope ratios, explains >85% of the observed variation and reproduces the observed slopes relating the isotopic composition of hair samples to that of local drinking water. Based on the geographical distributions of the isotope ratios of tap waters and the assumption of a “continental supermarket” dietary input, we constructed maps of the expected average H and O isotope ratios in human hair across the contiguous 48 states. Applications of this model and these observations are extensive and include detection of dietary information, reconstruction of historic movements of individuals, and provision of region-of-origin information for unidentified human remains. PMID:18299562

  19. Hydrogen and oxygen isotope ratios in human hair are related to geography.

    PubMed

    Ehleringer, James R; Bowen, Gabriel J; Chesson, Lesley A; West, Adam G; Podlesak, David W; Cerling, Thure E

    2008-02-26

    We develop and test a model to predict the geographic region-of-origin of humans based on the stable isotope composition of their scalp hair. This model incorporates exchangeable and nonexchangeable hydrogen and oxygen atoms in amino acids to predict the delta(2)H and delta(18)O values of scalp hair (primarily keratin). We evaluated model predictions with stable isotope analyses of human hair from 65 cities across the United States. The model, which predicts hair isotopic composition as a function of drinking water, bulk diet, and dietary protein isotope ratios, explains >85% of the observed variation and reproduces the observed slopes relating the isotopic composition of hair samples to that of local drinking water. Based on the geographical distributions of the isotope ratios of tap waters and the assumption of a "continental supermarket" dietary input, we constructed maps of the expected average H and O isotope ratios in human hair across the contiguous 48 states. Applications of this model and these observations are extensive and include detection of dietary information, reconstruction of historic movements of individuals, and provision of region-of-origin information for unidentified human remains.

  20. Silicon isotope ratio measurements by inductively coupled plasma tandem mass spectrometry for alteration studies of nuclear waste glasses.

    PubMed

    Gourgiotis, Alkiviadis; Ducasse, Thomas; Barker, Evelyne; Jollivet, Patrick; Gin, Stéphane; Bassot, Sylvain; Cazala, Charlotte

    2017-02-15

    High-level, long-lived nuclear waste arising from spent fuel reprocessing is vitrified in silicate glasses for final disposal in deep geologic formations. In order to better understand the mechanisms driving glass dissolution, glass alteration studies, based on silicon isotope ratio monitoring of (29)Si-doped aqueous solutions, were carried out in laboratories. This work explores the capabilities of the new type of quadrupole-based ICP-MS, the Agilent 8800 tandem quadrupole ICP-MS/MS, for accurate silicon isotope ratio determination for alteration studies of nuclear waste glasses. In order to avoid silicon polyatomic interferences, a new analytical method was developed using O2 as the reaction gas in the Octopole Reaction System (ORS), and silicon isotopes were measured in mass-shift mode. A careful analysis of the potential polyatomic interferences on SiO(+) and SiO2(+) ion species was performed, and we found that SiO(+) ion species suffer from important polyatomic interferences coming from the matrix of sample and standard solutions (0.5M HNO3). For SiO2(+), no interferences were detected, and thus, these ion species were chosen for silicon isotope ratio determination. A number of key settings for accurate isotope ratio analysis like, detector dead time, integration time, number of sweeps, wait time offset, memory blank and instrumental mass fractionation, were considered and optimized. Particular attention was paid to the optimization of abundance sensitivity of the quadrupole mass filter before the ORS. We showed that poor abundance sensitivity leads to a significant shift of the data away from the Exponential Mass Fractionation Law (EMFL) due to the spectral overlaps of silicon isotopes combined with different oxygen isotopes (i.e. (28)Si(16)O(18)O(+), (30)Si(16)O(16)O(+)). The developed method was validated by measuring a series of reference solutions with different (29)Si enrichment. Isotope ratio trueness, uncertainty and repeatability were found to be <0

  1. Direct uranium isotope ratio analysis of single micrometer-sized glass particles

    PubMed Central

    Kappel, Stefanie; Boulyga, Sergei F.; Prohaska, Thomas

    2012-01-01

    We present the application of nanosecond laser ablation (LA) coupled to a ‘Nu Plasma HR’ multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) for the direct analysis of U isotope ratios in single, 10–20 μm-sized, U-doped glass particles. Method development included studies with respect to (1) external correction of the measured U isotope ratios in glass particles, (2) the applied laser ablation carrier gas (i.e. Ar versus He) and (3) the accurate determination of lower abundant 236U/238U isotope ratios (i.e. 10−5). In addition, a data processing procedure was developed for evaluation of transient signals, which is of potential use for routine application of the developed method. We demonstrate that the developed method is reliable and well suited for determining U isotope ratios of individual particles. Analyses of twenty-eight S1 glass particles, measured under optimized conditions, yielded average biases of less than 0.6% from the certified values for 234U/238U and 235U/238U ratios. Experimental results obtained for 236U/238U isotope ratios deviated by less than −2.5% from the certified values. Expanded relative total combined standard uncertainties Uc (k = 2) of 2.6%, 1.4% and 5.8% were calculated for 234U/238U, 235U/238U and 236U/238U, respectively. PMID:22595724

  2. Isotopic ratios at z = 0.68 from molecular absorption lines toward B 0218+357

    NASA Astrophysics Data System (ADS)

    Wallström, S. H. J.; Muller, S.; Guélin, M.

    2016-11-01

    Isotopic ratios of heavy elements are a key signature of the nucleosynthesis processes in stellar interiors. The contribution of successive generations of stars to the metal enrichment of the Universe is imprinted on the evolution of isotopic ratios over time. We investigate the isotopic ratios of carbon, nitrogen, oxygen, and sulfur through millimeter molecular absorption lines arising in the z = 0.68 absorber toward the blazar B 0218+357. We find that these ratios differ from those observed in the Galactic interstellar medium, but are remarkably close to those in the only other source at intermediate redshift for which isotopic ratios have been measured to date, the z = 0.89 absorber in front of PKS 1830-211. The isotopic ratios in these two absorbers should reflect enrichment mostly from massive stars, and they are indeed close to the values observed toward local starburst galaxies. Our measurements set constraints on nucleosynthesis and chemical evolution models. The reduced spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A96

  3. Final report of the key comparison CCQM-K98: Pb isotope amount ratios in bronze

    NASA Astrophysics Data System (ADS)

    Vogl, Jochen; Yim, Yong-Hyeon; Lee, Kyoung-Seok; Goenaga-Infante, Heidi; Malinowskiy, Dmitriy; Ren, Tongxiang; Wang, Jun; Vocke, Robert D., Jr.; Murphy, Karen; Nonose, Naoko; Rienitz, Olaf; Noordmann, Janine; Näykki, Teemu; Sara-Aho, Timo; Ari, Betül; Cankur, Oktay

    2014-01-01

    Isotope amount ratios are proving useful in an ever increasing array of applications that range from studies unravelling transport processes, to pinpointing the provenance of specific samples as well as trace element quantification by using isotope dilution mass spectrometry (IDMS). These expanding applications encompass fields as diverse as archaeology, food chemistry, forensic science, geochemistry, medicine and metrology. However, to be effective tools, the isotope ratio data must be reliable and traceable to enable the comparability of measurement results. The importance of traceability and comparability in isotope ratio analysis has already been recognized by the Inorganic Analysis Working Group (IAWG) within the CCQM. While the requirements for isotope ratio accuracy and precision in the case of IDMS are generally quite modest, 'absolute' Pb isotope ratio measurements for geochemical applications as well as forensic provenance studies require Pb isotope ratio measurements of the highest quality. To support present and future CMCs on isotope ratio determinations, a key comparison was urgently needed and therefore initiated at the IAWG meeting in Paris in April 2011. The analytical task within such a comparison was decided to be the measurement of Pb isotope amount ratios in water and bronze. Measuring Pb isotope amount ratios in an aqueous Pb solution tested the ability of analysts to correct for any instrumental effects on the measured ratios, while the measurement of Pb isotope amount ratios in a metal matrix sample provided a real world test of the whole chemical and instrumental procedure. A suitable bronze material with a Pb mass fraction between 10 and 100 mg•kg-1 and a high purity solution of Pb with a mass fraction of approximately 100 mg•kg-1 was available at the pilot laboratory (BAM), both offering a natural-like Pb isotopic composition. The mandatory measurands, the isotope amount ratios n(206Pb)/n(204Pb), n(207Pb)/n(204Pb) and n(208Pb)/n(204Pb

  4. A Plant-Based Proxy for the Oxygen Isotope Ratio of Atmospheric Water Vapor

    NASA Astrophysics Data System (ADS)

    Helliker, B.

    2007-12-01

    Atmospheric water vapor is a major component of the global hydrological cycle, but the isotopic balance of vapor is largely unknown. It is shown here that the oxygen isotope ratio of leaf water in the epiphytic Crassulacean acid metabolism (CAM) plant Tillandsia usneoides (Spanish Moss) is controlled by the oxygen isotope ratio of atmospheric water vapor in both field and lab studies. Assuming that the leaf-water isotopic signature (and hence the atmospheric water vapor signature) is recorded in plant organic material, the atmospheric water vapor oxygen isotope ratios for Miami, Florida (USA) were reconstructed for several years from 1878 to 2005 using contemporary and herbarium specimens. T. usneoides ranges from Virginia, USA southwards through the tropics to Argentina, and the CAM epiphytic lifeform is widespread in other species. Therefore, epiphytes may be used to reconstruct the isotope ratio of atmospheric water for spatial scales that span over 60° of latitude and temporal scales that cover the last century of global temperature increase.

  5. Analysis of the hydrogen and oxygen stable isotope ratios of beverage waters without prior water extraction using isotope ratio infrared spectroscopy.

    PubMed

    Chesson, Lesley A; Bowen, Gabriel J; Ehleringer, James R

    2010-11-15

    Hydrogen (δ(2)H) and oxygen (δ(18)O) stable isotope analysis is useful when tracing the origin of water in beverages, but traditional analytical techniques are limited to pure or extracted waters. We measured the isotopic composition of extracted beverage water using both isotope ratio infrared spectroscopy (IRIS; specifically, wavelength-scanned cavity ring-down spectroscopy) and isotope ratio mass spectrometry (IRMS). We also analyzed beer, sodas, juices, and milk 'as is' using IRIS. For IRIS analysis, four sequential injections of each sample were measured and data were corrected for sample-to-sample memory using injections (a) 1-4, (b) 2-4, and (c) 3-4. The variation between δ(2)H and δ(18)O values calculated using the three correction methods was larger for unextracted (i.e., complex) beverages than for waters. The memory correction was smallest when using injections 3-4. Beverage water δ(2)H and δ(18)O values generally fit the Global Meteoric Water Line, with the exception of water from fruit juices. The beverage water stable isotope ratios measured using IRIS agreed well with the IRMS data and fit 1:1 lines, with the exception of sodas and juices (δ(2)H values) and beers (δ(18)O values). The δ(2)H and δ(18)O values of waters extracted from beer, soda, juice, and milk were correlated with complex beverage δ(2)H and δ(18)O values (r = 0.998 and 0.997, respectively) and generally fit 1:1 lines. We conclude that it is possible to analyze complex beverages, without water extraction, using IRIS although caution is needed when analyzing beverages containing sugars, which can clog the syringe and increase memory, or alcohol, a known spectral interference.

  6. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to ...

  7. Relation between hydrogen isotopic ratios of bone collagen and rain

    SciTech Connect

    Cormie, A.B.; Schwarcz, H.P. ); Gray, J. )

    1994-01-01

    The hydrogen isotopic value ([delta]D) of deer bone collagen is related to both [delta]D of rain during the growing season and growing season relative humidity (RH). With correction for the effects of RH, bone [delta]D is related to growing season rain [delta]D in a simple manner with a slope of 1.0. This indicates that, with RH correction, there are no additional sources of bias in the [delta]D of bone due to unaccounted for biologic or climatic effects. Due to a low sensitivity of bone [delta]D to RH effects, both yearly and growing season rain [delta]D can be estimated with considerable accuracy (R = 0.97 and R = 0.96) from bone collagen [delta]D and [delta][sup 15]N. Here, [delta][sup 15]N is used to correct bone [delta]D for the effects of RH. From these estimates of rain [delta]D, it may then be possible to evaluate temperature since the [delta]D of rain primarily reflects local temperature. Therefore, the measurement of bone collagen [delta]D has good potential for evaluating paleoclimates.

  8. Calculation of equilibrium stable isotope partition function ratios for aqueous zinc complexes and metallic zinc

    NASA Astrophysics Data System (ADS)

    Black, Jay R.; Kavner, Abby; Schauble, Edwin A.

    2011-02-01

    The goal of this study is to determine reduced partition function ratios for a variety of species of zinc, both as a metal and in aqueous solutions in order to calculate equilibrium stable isotope partitioning. We present calculations of the magnitude of Zn stable-isotope fractionation ( 66,67,68Zn/ 64Zn) between aqueous species and metallic zinc using measured vibrational spectra (fit from neutron scattering studies of metallic zinc) and a variety of electronic structure models. The results show that the reduced metal, Zn(0), will be light in equilibrium with oxidized Zn(II) aqueous species, with the best estimates for the Zn(II)-Zn(0) fractionation between hexaquo species and metallic zinc being Δ 66/64Zn aq-metal ˜ 1.6‰ at 25 °C, and Δ 66/64Zn aq-metal ˜ 0.8‰ between the tetrachloro zinc complex and metallic zinc at 25 °C using B3LYP/aug-cc-pVDZ level of theory and basis set. To examine the behavior of zinc in various aqueous solution chemistries, models for Zn(II) complex speciation were used to determine which species are thermodynamically favorable and abundant under a variety of different conditions relevant to natural waters, experimental and industrial solutions. The optimal molecular geometries for [Zn(H 2O) 6] 2+, [Zn(H 2O) 6]·SO 4, [ZnCl 4] 2- and [Zn(H 2O) 3(C 3H 5O(COO) 3)] - complexes in various states of solvation, protonation and coordination were calculated at various levels of electronic structure theory and basis set size. Isotopic reduced partition function ratios were calculated from frequency analyses of these optimized structures. Increasing the basis set size typically led to a decrease in the calculated reduced partition function ratios of ˜0.5‰ with values approaching a plateau using the aug-cc-pVDZ basis set or larger. The widest range of species were studied at the B3LYP/LAN2DZ/6-31G ∗ level of theory and basis-set size for comparison. Aqueous zinc complexes where oxygen is bound to the metal center tended to have the

  9. Isotope ratio analysis of individual sub-micrometer plutonium particles with inductively coupled plasma mass spectrometry.

    PubMed

    Esaka, Fumitaka; Magara, Masaaki; Suzuki, Daisuke; Miyamoto, Yutaka; Lee, Chi-Gyu; Kimura, Takaumi

    2010-12-15

    Information on plutonium isotope ratios in individual particles is of great importance for nuclear safeguards, nuclear forensics and so on. Although secondary ion mass spectrometry (SIMS) is successfully utilized for the analysis of individual uranium particles, the isobaric interference of americium-241 to plutonium-241 makes difficult to obtain accurate isotope ratios in individual plutonium particles. In the present work, an analytical technique by a combination of chemical separation and inductively coupled plasma mass spectrometry (ICP-MS) is developed and applied to isotope ratio analysis of individual sub-micrometer plutonium particles. The ICP-MS results for individual plutonium particles prepared from a standard reference material (NBL SRM-947) indicate that the use of a desolvation system for sample introduction improves the precision of isotope ratios. In addition, the accuracy of the (241)Pu/(239)Pu isotope ratio is much improved, owing to the chemical separation of plutonium and americium. In conclusion, the performance of the proposed ICP-MS technique is sufficient for the analysis of individual plutonium particles.

  10. Elemental concentrations and inorganic isotopic ratios in surface snow along the route to Dome Fuji, Antarctica

    NASA Astrophysics Data System (ADS)

    Hirabayashi, M.; Nakazawa, F.; Azuma, K. G.; Motoyama, H.

    2015-12-01

    Snow ice sample in Antarctica contains particulate matter. Particulates originate from continent, volcano, sea, space, and organism. The particulate matter of continental origin contains many elements from minerals and rocks. The isotopic ratio of an element reflects the origin and the history of the particle. Since the isotopic ratio of inorganic species depends on the source, the information about the source contribution of particulate matter can be estimated by analyzing the isotopic ratios of inorganic species. In this research, concentrations of inorganic species and isotopic ratios of inorganic species (Ca, Sr, Nd) in snow collected on the route form coastal area to Dome Fuji station in Antarctica were analyzed. The snow samples were collected along ca. 1000 km traverse route from Mikaeridai (S16; 69°01'S, 40°03'E, 590 m) to Dome Fuji station (77°19'S, 39°42'E, 3810 m) by the Japan Antarctica research expedition. Those samples were collected in the 2007/2008 and 2009/2010 austral summer. The samples were transported to Japan without thawing. The quantitative analyses of inorganic species were measured using ICP quadrupole type mass spectrometer. The isotopic ratios of isolated inorganic species were measured using ICP magnetic field type mass spectrometer. Further results and discussion about the behavior and origin of sulfur species in snow will be presented.

  11. Diffusion as a Rate Limiting Factor on the Evolution of Strontium Isotope Ratios in Fractured Rock

    NASA Astrophysics Data System (ADS)

    Johnson, E. G.; Holt, R. M.; McLing, T. L.

    2002-12-01

    In recent years, several approaches have been developed to model the evolution of strontium isotope ratios (87Sr/86Sr) in porous media. In fractured rock, however, diffusion limits the rates of reaction between mobile water and mineral surfaces inside fracture-bounded blocks. Diffusion can limit transfer of fluids with differing isotopic ratios between the mobile and immobile zones leading to longer equilibration times. We develop a diffusion-based mathematical approach for modeling the evolution of ratios that includes sorption, ion exchange, and dissolution in fracture bounded blocks of multiple sizes. Traditional models employing isotopic ratios with the advection-dispersion equation are unable to incorporate diffusion because they are limited by the structure of their equation. Modeling the individual isotopic species separately accounts for the effects of diffusion. The general governing equation is robust in that it does not assume chemical equilibrium reactions. Special cases show the importance of diffusion-limited mass transfer on the evolution of isotopes ratios in fractured rock.

  12. Determination of carbon isotopic measurement conditions for ceramide in skin using gas chromatography-combustion-isotope ratio mass spectrometry.

    PubMed

    Haraguchi, Hiroyuki; Yamada, Keita; Miyashita, Rumiko; Aida, Kazuhiko; Ohnishi, Masao; Gilbert, Alexis; Yoshida, Naohiro

    2014-01-01

    The ceramide (Cer) content of skin and glucosylceramide (GlcCer) intake affect skin moisture conditions, but their mutual relation in skin remains unclear. For clarification of that mutual relation, carbon stable isotopes ((12)C and (13)C) are useful as a tracer. However, carbon isotopic measurement has not been applied to the study of clarifying their skin moisturizing effects. Therefore, we used gas chromatography / combustion / isotope ratio mass spectrometry (GC-C-IRMS) to ascertain the appropriate conditions for carbon isotopic measurements using synthesized Cer (SCer) in substitution for very low concentrations of Cer in skin. SCer was derivatized to trimethylsilylated SCer (TMS-SCer) quantitatively using N-trimethylsilylimidazole (TMSI) depending on the amount of SCer. The derivatization rates were 75-85%. Excess TMSI was removed using three cycles of hexane-water distribution. Under these conditions, carbon isotopic measurements of TMS-SCer conducted using GC-C-IRMS showed high repeatability and good inter-day variation (S.D. < 0.3‰). The carbon stable isotope ratio value (δ(13)C) of SCer calculated using a mass balance equation was compared with δ(13)C of underivatized SCer, which was regarded as the actual δ(13)C of SCer obtained using sealed tube combustion method. The difference between the calculated δ(13)C of SCer and δ(13)C of the underivatized SCer depended on the TMSI reagent supplier and on the number of hydroxyl groups to be derivatized in SCer. For accurate δ(13)C of Cer in skin using GC-C-IRMS, the measured δ(13)C of a target TMS-Cer must be calculated using a correction factor representing the difference in δ(13)C of underivatized standard SCer from that of TMS-standard SCer having a structure resembling that of the target Cer in skin. In addition, we show that the same lot of TMSI reagent from a specific supplier must be used throughout the experiments.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Helium Isotopic Ratios of Core Samples from IODP Exp. 319 (NanTroSEIZE Stage 2)

    NASA Astrophysics Data System (ADS)

    Horiguchi, K.; Matsuda, J.; Wiersberg, T.; Shimo, Y.; Tamura, H.; Kumagai, H.; Suzuki, K.; Saito, S.; Kinoshita, M.; Araki, E.; Byrne, T.; McNeill, L. C.; Saffer, D.; Takahashi, K.; Eguchi, N. O.; Toczko, S.

    2009-12-01

    IODP Exp.319 of Nankai Trough Seismogenic Zone Drilling Program Stage 2 started at May 2009. Various advanced technologies including first riser-based scientific ocean drilling were carried out at this cruise. The Hole C0009A (Site C0009/ Hole A) recovered cutting and partly core samples from 703.9-1604 mbsf by riser-drilling. The core samples were collected between the depth of 1510.5 and 1593.9 mbsf. Here we report preliminary helium isotopic ratios of these cores. We collected three types of samples for our study: (1) gas of cores, (2) whole round cores (100 cc) and (3) small whole round cores (10 cc). The gas samples were taken immediately after the core recovery. The gas samples were collected from each core section by using a syringe, and it was transferred to the glass bottle using the water displacement method. The glass bottle was made by Pyrex glass with vacuum valve at each end. We collected two sizes of whole round core samples (100 cc and 10 cc) The 100 cc cores were collected from the bottom and top sections of coring. The 10 cc cores were taken from the other sections. The outer parts of these samples were carefully removed to avoid contaminations from drilling fluid. After the removal of contamination, we immediately stored the 100 cc samples into vacuum container and 10 cc samples into plastic bag under a dry condition, respectively. The gas samples were measured for helium isotopic ratios. The noble gas measurement was carried out at Osaka University by using VG5400 mass spectrometer. We measured helium isotopic ratio and 4He/20Ne ratio. The latter is useful for making correction of the air contamination. The obtained result of helium isotopic ratios shows that the radiogenic helium is prominent in all samples. In addition, the helium isotope ratios show a trend that the ratio at shallower part is slightly higher than that at deeper part. It is conceivable that this trend is due to the larger radiogenic ingrowths at the deeper part. However, the

  15. Line shift, line asymmetry, and the ^6Li/^7Li isotopic ratio determination

    NASA Astrophysics Data System (ADS)

    Cayrel, R.; Steffen, M.; Chand, H.; Bonifacio, P.; Spite, M.; Spite, F.; Petitjean, P.; Ludwig, H.-G.; Caffau, E.

    2007-10-01

    Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such asymmetries are usually neglected in abundance analyses. The determination of the ^6Li/^7Li isotopic ratio is prone to suffering from such asymmetries, as the contribution of ^6Li is a slight blending reinforcement of the red wing of each component of the corresponding ^7Li line, with respect to its blue wing. Aims: The present paper studies the halo star HD 74000 and estimates the impact of convection-related asymmetries on the Li isotopic ratio determination. Methods: Two methods are used to meet this aim. The first, which is purely empirical, consists in deriving a template profile from another element that can be assumed to originate in the same stellar atmospheric layers as Li I, producing absorption lines of approximately the same equivalent width as individual components of the ^7Li I resonance line. The second method consists in conducting the abundance analysis based on NLTE line formation in a 3D hydrodynamical model atmosphere, taking into account the effects of photospheric convection. Results: The results of the first method show that the convective asymmetry generates an excess absorption in the red wing of the ^7Li absorption feature that mimics the presence of ^6Li at a level comparable to the hitherto published values. This opens the possibility that only an upper limit on ^6Li/^7Li has thus far been derived. The second method confirms these findings. Conclusions: From this work, it appears that a systematic reappraisal of former determinations of ^6Li abundances in halo stars is warranted. Based on observations carried out at the European Southern Observatory (ESO), under prog. ID 75.D-0600. Tables 1-3, and additional references are only available in electronic form at http://www.aanda.org

  16. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry

    USGS Publications Warehouse

    Coplen, T.B.; Qi, H.

    2010-01-01

    An anomalous stable hydrogen isotopic fractionation of 4 ??? in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) ??2H reproducibility (1?? standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1 ??? to 0.58 ???. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen. ?? This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society.

  17. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry

    USGS Publications Warehouse

    Coplen, Tyler B.; Qi, Haiping

    2010-01-01

    An anomalous stable hydrogen isotopic fractionation of 4 ‰ in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) δ2H reproducibility (1& sigma; standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1‰ to 0.58 ‰. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen

  18. Carbon Isotope Measurements of Experimentally-Derived Hydrothermal Mineral-Catalyzed Organic Products by Pyrolysis-Isotope Ratio Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.

    2011-01-01

    We report results of experiments to measure the C isotope composition of mineral catalyzed organic compounds derived from high temperature and high pressure synthesis. These experiments make use of an innovative pyrolysis technique designed to extract and measure C isotopes. To date, our experiments have focused on the pyrolysis and C isotope ratio measurements of low-molecular weight intermediary hydrocarbons (organic acids and alcohols) and serve as a proof of concept for making C and H isotope measurements on more complicated mixtures of solid-phase hydrocarbons and intermediary products produced during high temperature and high pressure synthesis on mineral-catalyzed surfaces. The impetus for this work stems from recently reported observations of methane detected within the Martian atmosphere [1-4], coupled with evidence showing extensive water-rock interaction during Martian history [5-7]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization reactions [8,9]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [10-12]. Further, recent experiments by Fu et al. [13] focus on examining detailed C isotope measurements of hydrocarbons produced by surface-catalyzed mineral reactions. Work described in this paper details the experimental techniques used to measure intermediary organic reaction products (alcohols and organic acids).

  19. Tracing sewage and natural freshwater input in a northwest Mediterranean Bay: evidence obtained from isotopic ratios in marine organisms.

    PubMed

    Lassauque, J; Lepoint, G; Thibaut, T; Francour, P; Meinesz, A

    2010-06-01

    Elemental carbon and nitrogen levels and isotope ratios were assessed in different biological compartments of a Northwest (NW) Mediterranean bay to trace the various sources of nutrient input from natural (river runoffs) and anthropogenic (harbor outflows, fish farms and urban sewage outfall) sources. Samples from transplanted mussels and natural sea grass communities (Posidonia oceanica leaves and epiphytes) were harvested from different locations throughout the bay during the touristic summer and rainy seasons. The results from the nitrogen analysis revealed that sewage and harbor outflow promote higher nitrogen levels, enrichment of (15)N in the tissues, and a higher seasonal variability in sea grass and epiphytes. In mussel tissues, the delta(15)N was also influenced by sewage and harbor outflow, whereas delta(13)C was influenced by terrestrial inputs. These results suggest that natural and anthropogenic nutrient inputs have a temporary and localized influence and affect the sensitivity of natural isotopic ratios to changes in hydrologic conditions, especially to rain and tourism.

  20. A 40-year record of Northern Hemisphere atmospheric carbon monoxide concentration and isotope ratios from the firn at Greenland Summit.

    NASA Astrophysics Data System (ADS)

    Place, P., Jr.; Petrenko, V. V.; Vimont, I.; Buizert, C.; Lang, P. M.; Edwards, J.; Harth, C. M.; Hmiel, B.; Mak, J. E.; Novelli, P. C.; Brook, E.; Weiss, R. F.; Vaughn, B. H.; White, J. W. C.

    2014-12-01

    Carbon Monoxide (CO) is an important atmospheric trace gas that affects the oxidative capacity of the atmosphere and contributes indirectly to climate forcing by being a major sink of tropospheric OH. A good understanding of the past atmospheric CO budget is therefore important for climate models attempting to characterize recent changes in the atmosphere. Previous work at NEEM, Greenland provided the first reconstructions of Arctic atmospheric history of CO concentration and stable isotope ratios (δC18O and δ13CO) from firn air, dating to the 1950s. In this new study, firn air was sampled from eighteen depth levels through the firn column at Summit, Greenland (in May 2013), yielding a second, independent record of Arctic CO concentration and isotopic ratios. Carbon monoxide stable isotope ratios were analyzed on replicate samples and using a newly developed system with improved precision allowing for a more robust reconstruction. The new CO concentration and stable isotope results overall confirm the earlier findings from NEEM, with a CO concentration peak around the 1970s and higher δC18O and δ13CO values associated with peak CO. Modeling and interpretation of the data are in progress.

  1. The interstellar Li-7/Li-6 isotope ratio toward Zeta Ophiuchi and Zeta Persei

    NASA Technical Reports Server (NTRS)

    Meyer, David M.; Hawkins, Isabel; Wright, Edward L.

    1993-01-01

    High S/N, high-resolution observations of the interstellar Li absorption lines toward the stars Zeta Ophiuchi and Zeta Persei are reported. Li I line profiles indicate the presence of both the Li-7 and Li-6 doublets in these two sightlines. Best-fit values for the interstellar Li-7/Li-6 isotope ratio are 6.8 (+1.4/-1.7) towards Zeta Ophiuchi and 5.5 (+ 1.3/-1.1) toward Zeta Persei. Measurement of 6.8 (+1.4/-1.7) for the interstellar Li-7/Li-6 isotope ratio towards Zeta Ophiuchi does not support the lower limit of 25 determined by Ferlet and Dennefeld (1984). The current value of the interstellar Li-7/Li-6 isotope ratio is the result of various lithium production and destruction processes involving stars, cosmic rays, and the big bang.

  2. The puzzle of the CNO isotope ratios in asymptotic giant branch carbon stars

    NASA Astrophysics Data System (ADS)

    Abia, C.; Hedrosa, R. P.; Domínguez, I.; Straniero, O.

    2017-02-01

    Context. The abundance ratios of the main isotopes of carbon, nitrogen and oxygen are modified by the CNO-cycle in the stellar interiors. When the different dredge-up events mix the burning material with the envelope, valuable information on the nucleosynthesis and mixing processes can be extracted by measuring these isotope ratios. Aims: Previous determinations of the oxygen isotopic ratios in asymptotic giant branch (AGB) carbon stars were at odds with the existing theoretical predictions. We aim to redetermine the oxygen ratios in these stars using new spectral analysis tools and further develop discussions on the carbon and nitrogen isotopic ratios in order to elucidate this problem. Methods: Oxygen isotopic ratios were derived from spectra in the K-band in a sample of galactic AGB carbon stars of different spectral types and near solar metallicity. Synthetic spectra calculated in local thermodynamic equillibrium (LTE) with spherical carbon-rich atmosphere models and updated molecular line lists were used. The CNO isotope ratios derived in a homogeneous way, were compared with theoretical predictions for low-mass (1.5-3 M⊙) AGB stars computed with the FUNS code assuming extra mixing both during the RGB and AGB phases. Results: For most of the stars the 16O/17O/18O ratios derived are in good agreement with theoretical predictions confirming that, for AGB stars, are established using the values reached after the first dredge-up (FDU) according to the initial stellar mass. This fact, as far as the oxygen isotopic ratios are concerned, leaves little space for the operation of any extra mixing mechanism during the AGB phase. Nevertheless, for a few stars with large 16O/17O/18O, the operation of such a mechanism might be required, although their observed 12C/13C and 14N/15N ratios would be difficult to reconcile within this scenario. Furthermore, J-type stars tend to have lower 16O/17O ratios than the normal carbon stars, as already indicated in previous studies

  3. Application of neodymium isotope ratio measurements for the origin assessment of uranium ore concentrates.

    PubMed

    Krajkó, Judit; Varga, Zsolt; Yalcintas, Ezgi; Wallenius, Maria; Mayer, Klaus

    2014-11-01

    A novel procedure has been developed for the measurement of (143)Nd/(144)Nd isotope ratio in various uranium-bearing materials, such as uranium ores and ore concentrates (UOC) in order to evaluate the usefulness and applicability of variations of (143)Nd/(144)Nd isotope ratio for provenance assessment in nuclear forensics. Neodymium was separated and pre-concentrated by extraction chromatography and then the isotope ratios were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The method was validated by the measurement of standard reference materials (La Jolla, JB-2 and BCR-2) and the applicability of the procedure was demonstrated by the analysis of uranium samples of world-wide origin. The investigated samples show distinct (143)Nd/(144)Nd ratio depending on the ore type, deposit age and Sm/Nd ratio. Together with other characteristics of the material in question, the Nd isotope ratio is a promising signature for nuclear forensics and suggests being indicative of the source material, the uranium ore.

  4. On the cross-sensitivity between water vapor mixing ratio and stable isotope measurements of in-situ analyzers

    NASA Astrophysics Data System (ADS)

    Parkes, Stephen; Wang, Lixin; McCabe, Matthew

    2015-04-01

    In recent years there has been an increasing amount of water vapor stable isotope data collected using in-situ instrumentation. A number of papers have characterized the performance of these in-situ analyzers and suggested methods for calibrating raw measurements. The cross-sensitivity of the isotopic measurements on the mixing ratio has been shown to be a major uncertainty and a variety of techniques have been suggested to characterize this inaccuracy. However, most of these are based on relating isotopic ratios to water vapor mixing ratios from in-situ analyzers when the mixing ratio is varied and the isotopic composition kept constant. An additional correction for the span of the isotopic ratio scale is then applied by measuring different isotopic standards. Here we argue that the water vapor cross-sensitivity arises from different instrument responses (span and offset) of the parent H2O isotope and the heavier isotopes, rather than spectral overlap that could cause a true variation in the isotopic ratio with mixing ratio. This is especially relevant for commercial laser optical instruments where absorption lines are well resolved. Thus, the cross-sensitivity determined using more conventional techniques is dependent on the isotopic ratio of the standard used for the characterization, although errors are expected to be small. Consequently, the cross-sensitivity should be determined by characterizing the span and zero offset of each isotope mixing ratio. In fact, this technique makes the span correction for the isotopic ratio redundant. In this work we model the impact of changes in the span and offset of the heavy and light isotopes and illustrate the impact on the cross-sensitivity of the isotopic ratios on water vapor. This clearly shows the importance of determining the zero offset for the two isotopes. The cross-sensitivity of the isotopic ratios on water vapor is then characterized by determining the instrument response for the individual isotopes for a

  5. Correlation between multielement stable isotope ratio and geographical origin in Peretta cows' milk cheese.

    PubMed

    Manca, G; Franco, M A; Versini, G; Camin, F; Rossmann, A; Tola, A

    2006-03-01

    The aim of this study was to characterize the isotopic composition and protect "Peretta" cows' milk cheese, a typical product of Sardinia, against other cheeses of the same appearance sold under the same name, but made of raw materials from northern Europe. The study was concerned with 3 types of cheese: those produced in local dairies from milk from free-grazing or pasture-grazing cows in Sardinia (local dairy product), cheeses made on an industrial scale from milk produced by intensive farming in Sardinia (factory cheese), and cheeses made with raw materials imported from other countries (imported product). To distinguish the Sardinian cheeses from the imported product, the stable isotope ratios 13C/12C, 15N/14N, D/H, 34S/32S, and (18)O/(16)O were used. Determination of the isotopic data delta13C, delta15N, delta2H, and delta34S was performed in the casein fraction, whereas delta(18)O and delta13C were determined in the glycerol fraction. Measurements were performed by isotope ratio mass spectrometry. A comparison between mean values of the isotope ratios by statistical analysis (ANOVA and Tukey's test) showed that the greatest difference between the 3 types of cheese (local dairy, factory, and imported products) was in the 13C/12C, 34S/32S, and (18)O/(16)O isotope ratios. In the other parameters, either no differences (delta15N) or minimal differences (delta2H) were found. Evaluation of the data by multivariate statistical analysis (principal component analysis and hierarchical cluster analysis) revealed that the isotope characteristics of the factory products were similar to those of the cheeses produced from imported raw materials, whereas a difference was found between the local dairy-produced cheeses and the products in the other 2 categories.

  6. Carbon Isotopic Ratios of Amino Acids in Stardust-Returned Samples

    NASA Technical Reports Server (NTRS)

    Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.

    2009-01-01

    NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here. we present the carbon isotopic ratios of glycine and E-aminocaproic acid (EACH), the two most abundant amino acids observed, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio crass spectrometry coupled with quadrupole mass spectrometry (GC-QMS/IRMS).

  7. Spectral analysis software improves confidence in plant and soil water stable isotope analyses performed by isotope ratio infrared spectroscopy (IRIS).

    PubMed

    West, A G; Goldsmith, G R; Matimati, I; Dawson, T E

    2011-08-30

    Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isotope analysis. Here we report two independent tests of this post-processing spectral analysis software on two IRIS systems, OA-ICOS (Los Gatos Research Inc.) and WS-CRDS (Picarro Inc.). Following a similar methodology to a previous study, we cryogenically extracted plant leaf water and soil water and measured the δ(2)H and δ(18)O values of identical samples by isotope ratio mass spectrometry (IRMS) and IRIS. As an additional test, we analyzed plant stem waters and tap waters by IRMS and IRIS in an independent laboratory. For all tests we assumed that the IRMS value represented the "true" value against which we could compare the stable isotope results from the IRIS methods. Samples showing significant deviations from the IRMS value (>2σ) were considered to be contaminated and representative of spectral interference in the IRIS measurement. Over the two studies, 83% of plant species were considered contaminated on OA-ICOS and 58% on WS-CRDS. Post-analysis, spectra were analyzed using the manufacturer's spectral analysis software, in order to see if the software correctly identified contaminated samples. In our tests the software performed well, identifying all the samples with major errors. However, some false negatives indicate that user evaluation and testing of the software are necessary. Repeat sampling of plants showed considerable variation in the discrepancies between IRIS and IRMS. As such, we recommend that spectral analysis of IRIS data must be incorporated into standard post-processing routines. Furthermore, we suggest that the results from spectral analysis be

  8. Measurement of the stable carbon isotope ratio of atmospheric volatile organic compounds using chromatography, combustion, and isotope ratio mass spectrometry coupled with thermal desorption

    NASA Astrophysics Data System (ADS)

    Kawashima, Hiroto; Murakami, Mai

    2014-06-01

    The isotopic analysis of atmospheric volatile organic compounds (VOCs), and in particular of their stable carbon isotope ratio (δ13C), could potentially be used as an effective tool for identifying the sources of VOCs. However, to date, there have been very few such analyses. In this work, we analyze the δ13C values of VOCs using thermal desorption coupled with chromatography, combustion, and isotope ratio mass spectrometry (TD-GC/C/IRMS). The measured peak shapes were of high quality and 36 compounds in a standard gas containing 58 VOCs (C5-C11) were detected. The measured δ13C varied widely, from -49.7‰ to -22.9‰, while the standard deviation of the δ13C values varied from 0.07‰ to 0.85‰ (n = 5). We then measured samples from two passenger cars in hot and cold modes, three gas stations, roadside air, and ambient air. In comparison with existing studies, the analytical precision for the 36 compounds in this study was reasonable. By comparing the δ13C values obtained from the cars and gas stations, we could identify some degree of the sources of VOCs in the roadside and ambient air samples.

  9. Absolute Isotopic Abundance Ratios and Atomic Weight of a Reference Sample of Nickel

    PubMed Central

    Gramlich, J. W.; Machlan, L. A.; Barnes, I. L.; Paulsen, P. J.

    1989-01-01

    Absolute values have been obtained for the isotopic abundance ratios of a reference sample of nickel (Standard Reference Material 986), using thermal ionization mass spectrometry. Samples of known isotopic composition, prepared from nearly isotopically pure separated nickel isotopes, were used to calibrate the mass spectrometers. The resulting absolute isotopic ratios are: 58Ni/60Ni=2.596061±0.000728, 61Ni/60Ni=0.043469±0.000015,62Ni/60Ni=0.138600±0.000045, and 64Ni/60Ni=0.035295±0.000024, which yield atom percents of 58Ni=68.076886 ±0.005919, 60Ni = 26.223146±0.005144,61Ni=1.139894±0.000433, 62Ni =3.634528±0.001142, and 64Ni =0.925546±0.000599. The atomic weight calculated from this isotopic composition is 58.693353 ±0.000147. The indicated uncertainties are overall limits of error based on two standard deviations of the mean and allowances for the effects of known sources of possible systematic error. PMID:28053421

  10. Worldwide isotope ratios of the Fukushima release and early-phase external dose reconstruction

    PubMed Central

    Chaisan, Kittisak; Smith, Jim T.; Bossew, Peter; Kirchner, Gerald; Laptev, Gennady V.

    2013-01-01

    Measurements of radionuclides (RNs) in air made worldwide following the Fukushima accident are quantitatively compared with air and soil measurements made in Japan. Isotopic ratios RN:137Cs of 131I, 132Te, 134,136Cs, are correlated with distance from release. It is shown, for the first time, that both within Japan and globally, ratios RN:137Cs in air were relatively constant for primarily particle associated radionuclides (134,136Cs; 132Te) but that 131I shows much lower local (<80 km) isotope ratios in soils relative to 137Cs. Derived isotope ratios are used to reconstruct external dose rate during the early phase post-accident. Model “blind” tests show more than 95% of predictions within a factor of two of measurements from 15 sites to the north, northwest and west of the power station. It is demonstrated that generic isotope ratios provide a sound basis for reconstruction of early-phase external dose rates in these most contaminated areas. PMID:24018776

  11. Stable isotope ratio mass spectrometry of nanogram quantities of boron and sulfur

    NASA Astrophysics Data System (ADS)

    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

  12. Novel Apparatus for the Real-Time Quantification of Dissolved Gas Concentrations and Isotope Ratios

    NASA Astrophysics Data System (ADS)

    Gupta, M.; Leen, J.; Baer, D. S.; Owano, T. G.; Liem, J.

    2013-12-01

    Measurements of dissolved gases and their isotopic composition are critical in studying a variety of phenomena, including underwater greenhouse gas generation, air-surface exchange, and pollution migration. These studies typically involve obtaining water samples from streams, lakes, or ocean water and transporting them to a laboratory, where they are degased. The gases obtained are then generally measured using gas chromatography and isotope ratio mass spectrometry for concentrations and isotope ratios, respectively. This conventional, off-line methodology is time consuming, significantly limits the number of the samples that can be measured and thus severely inhibits detailed spatial and temporal mapping of gas concentrations and isotope ratios. In this work, we describe the development of a new membrane-based degassing device that interfaces directly to Los Gatos Research (cavity enhanced laser absorption or Off-Axis ICOS) gas analyzers (cavity enhanced laser absorption or Off-Axis ICOS analyzers) to create an autonomous system that can continuously and quickly measure concentrations and isotope ratios of dissolved gases in real time in the field. By accurately controlling the water flow rate through the membrane degasser, gas pressure on the outside of the membrane, and water pressure on the inside of the membrane, the system is able to generate precise and highly reproducible results. Moreover, by accurately measuring the gas flow rates in and out of the degasser, the gas-phase concentrations (ppm) could be converted into dissolved gas concentrations (nM). We will present detailed laboratory test data that quantifies the linearity, precision, and dynamic range of the system for the concentrations and isotope ratios of dissolved methane, carbon dioxide, and nitrous oxide. By interfacing the degassing device to a novel cavity-enhanced spectrometer (developed by LGR), preliminary data will also be presented for dissolved volatile organics (VOC) and other

  13. Disentangling effects of growth and nutritional status on seabird stable isotope ratios

    USGS Publications Warehouse

    Sears, J.; Hatch, Shyla A.; O'Brien, D. M.

    2009-01-01

    A growing number of studies suggest that an individual's physiology affects its carbon and nitrogen stable isotope signatures, obscuring a signal often assumed to be only a reflection of diet and foraging location. We examined effects of growth and moderate food restriction on red blood cell (RBC) and feather ??15N and ??13C in rhinoceros auklet chicks (Cerorhinca monocerata), a piscivorous seabird. Chicks were reared in captivity and fed either control (75 g/day; n = 7) or ~40% restricted (40 g/day; n = 6) amounts of high quality forage fish. We quantified effects of growth on isotopic fractionation by comparing ??15N and ??13C in control chicks to those of captive, non-growing subadult auklets (n = 11) fed the same diet. To estimate natural levels of isotopic variation, we also collected blood from a random sample of free-living rhinoceros auklet adults and chicks in the Gulf of Alaska (n = 15 for each), as well as adult feather samples (n = 13). In the captive experiment, moderate food restriction caused significant depletion in ??15N of both RBCs and feathers in treatment chicks compared to control chicks. Growth also induced depletion in RBC ??15N, with chicks exhibiting lower ??15N when they were growing the fastest. As growth slowed, ??15N increased, resulting in an overall pattern of enrichment over the course of the nestling period. Combined effects of growth and restriction depleted ??15N in chick RBCs by 0.92???. We propose that increased nitrogen-use efficiency is responsible for 15N depletion in both growing and food-restricted chicks. ??15N values in RBCs of free-ranging auklets fell within a range of only 1.03???, while feather ??15N varied widely. Together, our captive and field results suggest that both growth and moderate food restriction can affect stable isotope ratios in an ecologically meaningful way in RBCs although not feathers due to greater natural variability in this tissue. ?? 2008 Springer-Verlag.

  14. Stable lead isotopic ratios trace thermohaline circulation in the subarctic North Atlantic

    NASA Astrophysics Data System (ADS)

    Véron, A. J.; Church, T. M.; Rivera-Duarte, I.; Flegal, A. R.

    Vertical profiles of lead concentrations in the subarctic North Atlantic attest to the predominance of anthropogenic lead inputs to those waters, while variations in their lead isotopic ratios ( 204Pb : 206Pb : 207Pb : 208Pb) show the multiplicity of those industrial lead inputs. Spatial gradients in the isotopic ratios are consistent with the thermohaline circulation of different water masses, which seemingly have relatively discrete isotopic signatures. These include characteristic 206Pb/ 207Pb ratios of the North Atlantic Drift (1.183-1.187), Iceland-Scotland Overflow Water (1.173-1.176), Denmark Straits Overflow Water (1.179-1.182), and Labrador Sea Water (1.190-1.120). Based on parallels between these initial isotopic data and T- S measurements, it is proposed that stable lead isotopic compositions may be employed as complementary tracers of the mixing of source waters in the Nordic seas, as they overflow the Iceland-Scotland Ridge and Denmark Strait, mixing into the Labrador Sea to form North Atlantic Deep Water.

  15. Uranium Isotopic Ratio Measurements of U3O8 Reference Materials by Atom Probe Tomography

    SciTech Connect

    Fahey, Albert J.; Perea, Daniel E.; Bartrand, Jonah AG; Arey, Bruce W.; Thevuthasan, Suntharampillai

    2016-01-01

    We report results of measurements of isotopic ratios obtained with atom probe tomography on U3O8 reference materials certified for their isotopic abundances of uranium. The results show good agreement with the certified values. High backgrounds due to tails from adjacent peaks complicate the measurement of the integrated peak areas as well as the fact that only oxides of uranium appear in the spectrum, the most intense of which is doubly charged. In addition, lack of knowledge of other instrumental parameters, such as the dead time, may bias the results. Isotopic ratio measurements can be performed at the nanometer-scale with the expectation of sensible results. The abundance sensitivity and mass resolving power of the mass spectrometer are not sufficient to compete with magnetic-sector instruments but are not far from measurements made by ToF-SIMS of other isotopic systems. The agreement of the major isotope ratios is more than sufficient to distinguish most anthropogenic compositions from natural.

  16. Isotope ratio mass spectrometry as a tool for source inference in forensic science: A critical review.

    PubMed

    Gentile, Natacha; Siegwolf, Rolf T W; Esseiva, Pierre; Doyle, Sean; Zollinger, Kurt; Delémont, Olivier

    2015-06-01

    Isotope ratio mass spectrometry (IRMS) has been used in numerous fields of forensic science in a source inference perspective. This review compiles the studies published on the application of isotope ratio mass spectrometry (IRMS) to the traditional fields of forensic science so far. It completes the review of Benson et al. [1] and synthesises the extent of knowledge already gathered in the following fields: illicit drugs, flammable liquids, human provenancing, microtraces, explosives and other specific materials (packaging tapes, safety matches, plastics, etc.). For each field, a discussion assesses the state of science and highlights the relevance of the information in a forensic context. Through the different discussions which mark out the review, the potential and limitations of IRMS, as well as the needs and challenges of future studies are emphasized. The paper elicits the various dimensions of the source which can be obtained from the isotope information and demonstrates the transversal nature of IRMS as a tool for source inference.

  17. Improved precision and accuracy in quantifying plutonium isotope ratios by RIMS

    SciTech Connect

    Isselhardt, B. H.; Savina, M. R.; Kucher, A.; Gates, S. D.; Knight, K. B.; Hutcheon, I. D.

    2015-09-01

    Resonance ionization mass spectrometry (RIMS) holds the promise of rapid, isobar-free quantification of actinide isotope ratios in as-received materials (i.e. not chemically purified). Recent progress in achieving this potential using two Pu test materials is presented. RIMS measurements were conducted multiple times over a period of two months on two different Pu solutions deposited on metal surfaces. Measurements were bracketed with a Pu isotopic standard, and yielded absolute accuracies of the measured 240Pu/239Pu ratios of 0.7% and 0.58%, with precisions (95% confidence intervals) of 1.49% and 0.91%. In conclusion, the minor isotope 238Pu was also quantified despite the presence of a significant quantity of 238U in the samples.

  18. Improved precision and accuracy in quantifying plutonium isotope ratios by RIMS

    DOE PAGES

    Isselhardt, B. H.; Savina, M. R.; Kucher, A.; ...

    2015-09-01

    Resonance ionization mass spectrometry (RIMS) holds the promise of rapid, isobar-free quantification of actinide isotope ratios in as-received materials (i.e. not chemically purified). Recent progress in achieving this potential using two Pu test materials is presented. RIMS measurements were conducted multiple times over a period of two months on two different Pu solutions deposited on metal surfaces. Measurements were bracketed with a Pu isotopic standard, and yielded absolute accuracies of the measured 240Pu/239Pu ratios of 0.7% and 0.58%, with precisions (95% confidence intervals) of 1.49% and 0.91%. In conclusion, the minor isotope 238Pu was also quantified despite the presence ofmore » a significant quantity of 238U in the samples.« less

  19. Assessing connectivity of estuarine fishes based on stable isotope ratio analysis

    NASA Astrophysics Data System (ADS)

    Herzka, Sharon Z.

    2005-07-01

    Assessing connectivity is fundamental to understanding the population dynamics of fishes. I propose that isotopic analyses can greatly contribute to studies of connectivity in estuarine fishes due to the high diversity of isotopic signatures found among estuarine habitats and the fact that variations in isotopic composition at the base of a food web are reflected in the tissues of consumers. Isotopic analysis can be used for identifying nursery habitats and estimating their contribution to adult populations. If movement to a new habitat is accompanied by a shift to foods of distinct isotopic composition, recent immigrants and residents can be distinguished based on their isotopic ratios. Movement patterns thus can be reconstructed based on information obtained from individuals. A key consideration is the rate of isotopic turnover, which determines the length of time that an immigrant to a given habitat will be distinguishable from a longtime resident. A literature survey indicated that few studies have measured turnover rates in fishes and that these have focused on larvae and juveniles. These studies reveal that biomass gain is the primary process driving turnover rates, while metabolic turnover is either minimal or undetectable. Using a simple dilution model and biomass-specific growth rates, I estimated that young fishes with fast growth rates will reflect the isotopic composition of a new diet within days or weeks. Older or slower-growing individuals may take years or never fully equilibrate. Future studies should evaluate the factors that influence turnover rates in fishes during various stages of the life cycle and in different tissues, as well as explore the potential for combining stable isotope and otolith microstructure analyses to examine the relationship between demographic parameters, movement and connectivity.

  20. Homogeneous diet of contemporary Japanese inferred from stable isotope ratios of hair

    NASA Astrophysics Data System (ADS)

    Kusaka, Soichiro; Ishimaru, Eriko; Hyodo, Fujio; Gakuhari, Takashi; Yoneda, Minoru; Yumoto, Takakazu; Tayasu, Ichiro

    2016-09-01

    The globalization of food production and distribution has homogenized human dietary patterns irrespective of geography, but it is uncertain how far this homogenization has progressed. This study investigated the carbon and nitrogen isotope ratios in the scalp hair of 1305 contemporary Japanese and found values of ‑19.4 ± 0.6‰ and 9.4 ± 0.6‰ (mean ± SD), respectively. Within Japan, the inter-regional differences for both isotope ratios was less than 1‰, which indicates low dietary heterogeneity among prefectural divisions. The carbon and nitrogen isotope ratios of the hair showed a significant correlation with the results of questionnaires on self-reported dietary habits. The carbon isotope ratios from Japan were lower than those in samples from the USA but higher than those in samples from Europe. These differences stem from the varying dietary proportions of food products originally derived from C3 and C4 plants. The dietary variation of Japan is as small as those of Europe and USA and smaller than those of some Asian countries. These results indicate that dietary homogeneity has progressed in Japan, which may indicate the influence from the spread of the Western-style diet and food globalization, although dietary heterogeneity among countries is still preserved.

  1. Carbon and nitrogen isotope ratios of juvenile winter flounder as indicators of inputs to estuarine systems

    EPA Science Inventory

    Stable carbon and nitrogen isotope ratios were measured in the muscle tissues of young-of-the-year (YOY) winter flounder, Pseudopleuronectes americanus, collected from several estuarine systems along the coast of Rhode Island, USA. These systems included three coastal lagoons (Ni...

  2. Stabel Carbon and Oxygen Isotope Ratios of Otoliths from Juvenile and Adult Winter Flounder

    EPA Science Inventory

    This study was designed to determine if stable carbon (13C) and oxygen (18O) isotope ratios in otoliths could be used to differentiate the locations that serve as important nursery areas for winter flounder along the Rhode Island, USA coastline. In recent years the populations ...

  3. Stable Carbon and Oxygen Isotope Ratios of Otoliths Differentiate Winter Flounder (Pseudopleuonectes americanus) Habitats

    EPA Science Inventory

    Stable carbon (13C) and oxygen (18O) isotope ratios were measured in otoliths of juvenile winter flounder (Pseudopleuronectes americanus) collected from 18 nursery areas along the coast of Rhode Island, USA. Samples were obtained during June and July of 2002 from locations tha...

  4. Correlation of carbon isotope ratios in the cellulose and wood extractives of Douglas-fir

    EPA Science Inventory

    Cellulose is usually isolated from the other components of plant material for analysis of carbon stable isotope ratios (δ13C). However, many studies have shown a strong correlation between whole-wood and cellulose δ13C values, prompting debate about the necessity of cellulose ext...

  5. Homogeneous diet of contemporary Japanese inferred from stable isotope ratios of hair

    PubMed Central

    Kusaka, Soichiro; Ishimaru, Eriko; Hyodo, Fujio; Gakuhari, Takashi; Yoneda, Minoru; Yumoto, Takakazu; Tayasu, Ichiro

    2016-01-01

    The globalization of food production and distribution has homogenized human dietary patterns irrespective of geography, but it is uncertain how far this homogenization has progressed. This study investigated the carbon and nitrogen isotope ratios in the scalp hair of 1305 contemporary Japanese and found values of −19.4 ± 0.6‰ and 9.4 ± 0.6‰ (mean ± SD), respectively. Within Japan, the inter-regional differences for both isotope ratios was less than 1‰, which indicates low dietary heterogeneity among prefectural divisions. The carbon and nitrogen isotope ratios of the hair showed a significant correlation with the results of questionnaires on self-reported dietary habits. The carbon isotope ratios from Japan were lower than those in samples from the USA but higher than those in samples from Europe. These differences stem from the varying dietary proportions of food products originally derived from C3 and C4 plants. The dietary variation of Japan is as small as those of Europe and USA and smaller than those of some Asian countries. These results indicate that dietary homogeneity has progressed in Japan, which may indicate the influence from the spread of the Western-style diet and food globalization, although dietary heterogeneity among countries is still preserved. PMID:27616586

  6. Breath carbon stable isotope ratios identify changes in energy balance and substrate utilization in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rapid detection of shifts in substrate utilization and energy balance would provide a compelling biofeedback tool to enable individuals to lose weight. In a pilot study, we tested whether the natural abundance of exhaled carbon stable isotope ratios (breath d13C values) reflects shifts between negat...

  7. Stable nitrogen isotope ratios and accumulation of various HOCs in northern Baltic aquatic food chains

    SciTech Connect

    Broman, D.; Axelman, J.; Bergqvist, P.A.; Naef, C.; Rolff, C.; Zebuehr, Y.

    1995-12-31

    Ratios of naturally occurring stable isotopes of nitrogen ({delta}{sup 15}N) can be used to numerically classify trophic levels of organisms in food chains. By combining analyses results of various HOCs (e.g. PCDD/Fs, PCBs, DDTs, HCHs and some other pesticides) the biomagnification of these substances can be quantitatively estimated. In this paper different pelagic and benthic northern Baltic food chains were studied. The {delta}{sup 15}N-data gave food chain descriptions qualitatively consistent with previous conceptions of trophic arrangements in the food chains. The different HOCs concentrations were plotted versus the {delta}{sup 15}N-values for the different trophic levels and an exponential model of the form e{sup (A+B*{delta}N)} was fitted to the data. The estimates of the constant B in the model allows for an estimation of a biomagnification power (B) of different singular, or groups of, contaminants. A B-value around zero indicates that a substance is flowing through the food chain without being magnified, whereas a value > 0 indicates that a substance is biomagnified. Negative B-values indicate that a substance is not taken up or is metabolized. The A-term of the expression is only a scaling factor depending on the background level of the contaminant.

  8. The IRHUM database - bioavailable strontium isotope ratios of France for geochemical fingerprinting

    NASA Astrophysics Data System (ADS)

    Willmes, Malte; Moffat, Ian; Grün, Rainer; Armstrong, Richard; Kinsley, Les; McMorrow, Linda

    2013-04-01

    Strontium isotope ratios (87Sr/86Sr) are used as a geochemical tracer in a wide range of fields including archaeology, ecology, soil, food and forensic sciences. These applications are based on the principle that strontium isotopic ratios of materials reflect the geological sources of the strontium, which were available during its formation. Geologic regions with distinct strontium isotope ranges, which depend on their age and composition, can be differentiated. A major constraint for current studies is the lack of robust reference maps to evaluate the strontium isotope ratios measured in the samples. The aim of the IRHUM (isotopic reconstruction of human migration) database is to provide a reference map of bioavailable strontium isotope ratios for continental France. The current dataset contains 400 sample locations covering the major geologic units of the Paris and Aquitaine Basin, the Massif Central, and the Pyrenees. At each site soil and plant samples have been collected to cover the whole range of strontium ratios at a specific location. The database is available online at www.rses.anu.edu.au/research-areas/archaeogeochemistry and contains the bioavailable strontium isotope data as well as major and trace element concentrations for soil and plant samples. Strontium isotopes were analysed using a Neptune multi-collector inductively-coupled plasma mass spectrometer (MC-ICP-MS) and elemental concentrations with a Varian Vista Pro Axial ICP-AES (inductively-coupled plasma atomic emission spectrometer). In addition, IRHUM provides spatial context for each sample, including background geology, field observations and soil descriptions. This metadata allows users to evaluate the suitability of a specific data point for their study. The IRHUM database fills an important gap between high resolution studies from specific sites (e.g. archaeological sites), to the very broad geochemical mapping of Europe. Thus it provides an excellent tool to evaluate the regional context

  9. Coupling groundwater residence time and 234U/238U isotopic ratios in a granitic catchment (Vosges, Eastern France)

    NASA Astrophysics Data System (ADS)

    Viville, Daniel; Aquilina, Luc; Ackerer, Julien; Chatton, Eliot; Labasque, Thierry; Pierret, Marie-Claire; Granet, Mathieu; Perrone, Thierry; Chabaux, François

    2016-04-01

    Weathering processes are active in surface waters but groundwater also represents no neglectable chemical fluxes. As residence-time in groundwater are high, silicate weathering might take place and control Si, Ca and C fluxes. Weathering processes can be deduced from U isotopic ratios but the kinetics of these processes remain relatively poorly constrained. In order to better characterize these processes, we have coupled residence-times deduced from anthropogenic gases (CFC and SF6) analysis and 234U/238U isotopic ratios determination. Samples were collected in the Strengbach catchment (Hydro-geochemical Observatory OHGE, Vosges, eastern France). Two campaigns were carried out in May and August 2015 during two highly contrasted hydro-climatic periods. Both springs and boreholes down to 80 m depth have been sampled. A very clear geochemical distinction is observed between groundwater from surface springs and deeper groundwater from boreholes. Springs show much lower residence-time (few years) and specific chemical composition. Deeper groundwater have residence-time of several decades and different geochemical composition. A clear SF6 production is observed with increasing SF6 concentrations with residence-time. The campaign of May is characterized by highly groundwater levels and spring fluxes. All groundwater show very low residence time, except in the boreholes at depth greater than 40 m. Conversely, during low groundwater-level period in August, the residence times are much higher and CFC concentrations indicate a large mixing process between surface groundwater and deeper levels. The 234U/238U isotopic ratios confirm this vertical zonation in the boreholes, with much higher activity ratios in the deep ground-waters from borehole than in the surface and spring waters; Such high U activity ratios are indicative of long water-rock interactions, which is consistent with the long residence times deducted from the CFC and SF6 data.

  10. On-line determination of oxygen isotope ratios of water or ice by mass spectrometry.

    PubMed

    Leuenberger, M; Huber, C

    2002-09-15

    Oxygen isotope ratio determination on any of the water phases (water vapor, water, ice) is of great relevance in different research fields such as climate and paleoclimate studies, geological surveys, and hydrological studies. The conventional technique for oxygen isotope measurement involves equilibration with carbon dioxide gas for a given time with a subsequent isotope determination. The equilibration technique is available in different layouts, but all of them are rather time-consuming. Here we report a new on-line technique that processes water samples as well as ice samples. The same principal, CO2 hydration, is used but speeded up by (i) a direct injection and full dissolution of CO2 in the water, (ii) an increased isotope exchange temperature at 50 degrees C, and (iii) a rapid gas extraction by means of an air-permeable membrane into a continuous helium flux supplying the isotope ratio mass spectrometer with the sample gas. The precision is better than 0.1/1000 which is only slightly larger than with the conventional equilibration technique. This on-line technique allows analysis of 1 m of ice with a resolution of 1-3 cm, depending on the meltwater flux, within 1 h. Similarly, continuous and fast analysis can be performed for aqueous samples for hydrological, geological, and perhaps medical applications.

  11. Simulating stable carbon and chlorine isotope ratios in dissolved chlorinated groundwater pollutants with BIOCHLOR-ISO.

    PubMed

    Höhener, Patrick

    2016-12-01

    BIOCHLOR is a well-known simple tool for evaluating the transport of dissolved chlorinated solvents in groundwater, ideal for rapid screening and teaching. This work extends the BIOCHLOR model for the calculation of stable isotope ratios of carbon and chlorine isotopes in chloroethenes. An exact solution for the three-dimensional reactive transport of a chain of degrading compounds including sorption is provided in a spreadsheet and applied for modeling the transport of individual isotopes (12)C, (13)C, (35)Cl, (37)Cl from a constant source. The model can consider secondary isotope effects that can occur in the breaking of CCl bonds. The model is correctly reproducing results for δ(13)C and δ(37)Cl modeled by a previously published 1-D numerical model without secondary isotope effects, and is also reproducing results from a microcosm experiment with secondary chlorine isotope effects. Two applications of the model using field data from literature are further given and discussed. The new BIOCHLOR-ISO model is distributed as a spreadsheet (MS EXCEL) along with this publication.

  12. Simulating oxygen isotope ratios in tree ring cellulose using a dynamic global vegetation model

    NASA Astrophysics Data System (ADS)

    Keel, Sonja G.; Joos, Fortunat; Spahni, Renato; Saurer, Matthias; Weigt, Rosemarie B.; Klesse, Stefan

    2016-07-01

    Records of stable oxygen isotope ratios in tree rings are valuable tools to reconstruct past climatic conditions and investigate the response of trees to those conditions. So far the use of stable oxygen isotope signatures of tree rings has not been systematically evaluated in dynamic global vegetation models (DGVMs). DGVMs integrate many hydrological and physiological processes and their application could improve proxy-model comparisons and the interpretation of oxygen isotope records. Here we present an approach to simulate leaf water and stem cellulose δ18O of trees using the LPX-Bern DGVM (LPX-Bern). Our results lie within a few per mil of measured tree ring δ18O of 31 different forest stands mainly located in Europe. Temporal means over the last 5 decades as well as interannual variations for a subset of sites in Switzerland are captured. A sensitivity analysis reveals that relative humidity, temperature, and the water isotope boundary conditions have the largest influence on simulated stem cellulose δ18O, followed by all climatic factors combined, whereas increasing atmospheric CO2 and nitrogen deposition exert no impact. We conclude that simulations with LPX-Bern are useful for investigating large-scale oxygen isotope patterns of tree ring cellulose to elucidate the importance of different environmental factors on isotope variations and therefore help to reduce uncertainties in the interpretation of δ18O of tree rings.

  13. Simulating stable carbon and chlorine isotope ratios in dissolved chlorinated groundwater pollutants with BIOCHLOR-ISO

    NASA Astrophysics Data System (ADS)

    Höhener, Patrick

    2016-12-01

    BIOCHLOR is a well-known simple tool for evaluating the transport of dissolved chlorinated solvents in groundwater, ideal for rapid screening and teaching. This work extends the BIOCHLOR model for the calculation of stable isotope ratios of carbon and chlorine isotopes in chloroethenes. An exact solution for the three-dimensional reactive transport of a chain of degrading compounds including sorption is provided in a spreadsheet and applied for modeling the transport of individual isotopes 12C, 13C, 35Cl, 37Cl from a constant source. The model can consider secondary isotope effects that can occur in the breaking of Csbnd Cl bonds. The model is correctly reproducing results for δ13C and δ37Cl modeled by a previously published 1-D numerical model without secondary isotope effects, and is also reproducing results from a microcosm experiment with secondary chlorine isotope effects. Two applications of the model using field data from literature are further given and discussed. The new BIOCHLOR-ISO model is distributed as a spreadsheet (MS EXCEL) along with this publication.

  14. Forensic utility of the carbon isotope ratio of PVC tape backings

    NASA Astrophysics Data System (ADS)

    Stern, L. A.; Thompson, A. H.; Mehltretter, A. H.; McLaskey, V.; Parish, A.; Aranda, R.

    2008-12-01

    Forensic interest in adhesive tapes with PVC-backings (polyvinyl chloride, electrical tapes) derives from their use in construction of improvised explosive devices, drug packaging and in a variety of other illicit activities. Due to the range of physical characteristics and chemical compositions of such tapes, traditional microscopic and chemical analysis of the tape backings and adhesives offer a high degree of discrimination between tapes from different manufacturers and products. To evaluate whether carbon isotope ratios may be able to increase discrimination of electrical tapes, particularly with regards to different tapes of the same product, we assessed the PVC-backings of 87 rolls of black electrical tape for their δ13C values. The adhesive on these tapes was physically removed with hexane, and plasticizers within the PVC tape backings were removed by three-20 minute extractions with chloroform. The δ13C values of the PVC tape backings ranged between -23.8 and -41.5 (‰ V-PDB). The carbon isotopic variation within a product (identical brand and product identification) is significant, based on five products with at least 3 rolls (ranges of 7.4‰ (n=3), 10.0‰ (n=6), 4.2‰ (n=16), 3.8‰ (n=6), and 11.5‰ (n=8), respectively). There was no measurable carbon isotope variation in regards to the following: a) along the length of a roll (4 samples from 1 roll); b) between the center and edge of a strip of tape (1 pair); c) between rolls assumed to be from the same lot of tape (2 pairs); d) between different rolls from the same batch of tape (same product purchased at the same time and place; 5 pairs); and e) between samples of a tape at room temperature, heated to 50° C and 80° C for 1 week. For each sample within the population of 87 tapes, carbon isotopes alone exclude 80 to 100% of the tapes as a potential match, with an average exclusion power of 92.5%, using a window of ± 0.4‰. Carbon isotope variations originate from variations in starting

  15. Dietary Heterogeneity among Western Industrialized Countries Reflected in the Stable Isotope Ratios of Human Hair

    PubMed Central

    Valenzuela, Luciano O.; Chesson, Lesley A.; Bowen, Gabriel J.; Cerling, Thure E.; Ehleringer, James R.

    2012-01-01

    Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization). Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ13C values (−22.7 to −18.3‰), and significantly higher δ15N (7.8 to 10.3‰) and δ34S (4.8 to 8.3‰) values than samples from the USA (δ13C: −21.9 to −15.0‰, δ15N: 6.7 to 9.9‰, δ34S: −1.2 to 9.9‰). Within Europe, we detected differences in hair δ13C and δ34S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments. PMID:22479574

  16. Identifying the change in atmospheric sulfur sources in China using isotopic ratios in mosses

    NASA Astrophysics Data System (ADS)

    Xiao, Hua-Yun; Tang, Cong-Guo; Xiao, Hong-Wei; Liu, Xue-Yan; Liu, Cong-Qiang

    2009-08-01

    A considerable number of studies on rainwater sulfur isotopic ratios (δ34Srain) have been conducted to trace sulfur sources at a large number of sites in the past. If longitudinal studies on the isotope composition of precipitation sulfate were conducted, it is possible to relate that to changes in sulfur emissions. But direct measurement needs considerable labor and time. So, in this study, sulfur isotopic ratios in rainwater and mosses were analyzed at Guiyang and Nanchang to evaluate the possibility of using mosses as a substitute for rainwater. We found that present moss sulfur isotopic ratios were comparable to those of present rainwater. Additionally, we investigated the changes of atmospheric sulfur sources and sulfur concentrations using an isotopic graphic analysis at five industrial cities, two forested areas, and two remote areas in China. Mosses in industrial cities show a wide range of δ34S values, with the highest occurring at Chongqing (+3.9‰) and the lowest at Guiyang (-3.1‰). But as compared to those in forested and remote areas, δ34S values of mosses in all the five industrial cities are lower. On the basis of isotopic comparisons between past rainwater (reported in the literature) and present mosses, in the plot of δ34Smoss versus δ34Srain, six zones indicating different atmospheric sulfur change are separated by the 1:1 line and δ34S values of potential sulfur sources. Our results indicate that atmospheric sulfur pollution in most of the industrial cities decreased, while at the two forested areas, no significant changes were observed, and a new anxiousness coming from new energy sources (e.g., oil) appeared in some cities. Studies on the change of ambient SO2 concentrations support these results.

  17. Selenium stable isotope ratios in California agricultural drainage water management systems

    USGS Publications Warehouse

    Herbel, M.J.; Johnson, T.M.; Tanji, K.K.; Gao, S.; Bullen, T.D.

    2002-01-01

    Selenium stable isotope ratios are known to shift in predictable ways during various microbial, chemical, and biological processes, and can be used to better understand Se cycling in contaminated environments. In this study we used Se stable isotopes to discern the mechanisms controlling the transformation of oxidized, aqueous forms of Se to reduced, insoluble forms in sediments of Se-affected environments. We measured 80Se/76Se in surface waters, shallow ground waters, evaporites, digested plants and sediments, and sequential extracts from several sites where agricultural drainage water is processed in the San Joaquin Valley of California. Selenium isotope analyses of samples obtained from the Tulare Lake Drainage District flow-through wetland reveal small isotopic contrasts (mean difference 0.7%o) between surface water and reduced Se species in the underlying sediments. Selenium in aquatic macrophytes was very similar isotopically to the NaOH and Na2SO3 sediment extracts designed to recover soluble organic Se and Se(O), respectively. For the integrated on-farm drainage management sites, evaporite salts were slightly (approximately 0.6%o) enriched in the heavier isotope relative to the inferred parent waters, whereas surface soils were slightly (approximately 1.4%o) depleted. Bacterial or chemical reduction of Se(VI) or Se(IV) may be occurring at these sites, but the small isotopic contrasts suggest that other, less isotopically fractionating mechanisms are responsible for accumulation of reduced forms in the sediments. These findings provide evidence that Se assimilation by plants and algae followed by deposition and mineralization is the dominant transformation pathway responsible for accumulation of reduced forms of Se in the wetland sediments.

  18. Selenium stable isotope ratios in California agricultural drainage water management systems.

    PubMed

    Herbel, Mitchell J; Johnson, Thomas M; Tanji, Kenneth K; Gao, Suduan; Bullen, Thomas D

    2002-01-01

    Selenium stable isotope ratios are known to shift in predictable ways during various microbial, chemical, and biological processes, and can be used to better understand Se cycling in contaminated environments. In this study we used Se stable isotopes to discern the mechanisms controlling the transformation of oxidized, aqueous forms of Se to reduced, insoluble forms in sediments of Se-affected environments. We measured 80Se/76Se in surface waters, shallow ground waters, evaporites, digested plants and sediments, and sequential extracts from several sites where agricultural drainage water is processed in the San Joaquin Valley of California. Selenium isotope analyses of samples obtained from the Tulare Lake Drainage District flow-through wetland reveal small isotopic contrasts (mean difference 0.7%) between surface water and reduced Se species in the underlying sediments. Selenium in aquatic macrophytes was very similar isotopically to the NaOH and Na2SO3 sediment extracts designed to recover soluble organic Se and Se(0), respectively. For the integrated on-farm drainage management sites, evaporite salts were slightly (approximately 0.6%) enriched in the heavier isotope relative to the inferred parent waters, whereas surface soils were slightly (approximately 1.4%) depleted. Bacterial or chemical reduction of Se(VI) or Se(IV) may be occurring at these sites, but the small isotopic contrasts suggest that other, less isotopically fractionating mechanisms are responsible for accumulation of reduced forms in the sediments. These findings provide evidence that Se assimilation by plants and algae followed by deposition and mineralization is the dominant transformation pathway responsible for accumulation of reduced forms of Se in the wetland sediments.

  19. Isotope Ratio Mass Spectrometry and Shale Gas - What Is Possible with Current Technology?

    NASA Astrophysics Data System (ADS)

    Barrie, C. D.; Kasson, A.

    2014-12-01

    With ever increasing exploration and exploitation of 'unconventional' hydrocarbon resources, the drive to understand the origins, history and importance of these resources and their effects on the surrounding environment (i.e. ground waters) has never been more important. High-throughput, high-precision isotopic measurements are therefore a key tool in this industry to both understand the gas generated and monitor the development and stability of wells through time. With the advent of cavity ringdown spectroscopy (CRDS) instrumentation, there has been a push in some applications - environmental & atmospheric - to gather more and more data directly at the location of collection or at dedicated field stations. Furthermore, CRDS has resulted in users seeking greater autonomy of instrumentation and so-called black box technology. Traditionally IRMS technology has not met any of these demands, requiring very specific and extensive footprint, power and environmental requirements. This has meant that the 'Oil & Gas' sector, which for natural gases measurements requires GC-IRMS technology - not possible via CRDS - loses time, money and manpower as samples get sent to central facility or contract labs with potentially long lee times. However, recent developments in technology mean that IRMS systems exist which are benchtop, have much lower power requirements, standard power connections and as long as housed in a temperature controlled field stations can be deployed anywhere. Furthermore, with advances in electronics and software IRMS systems are approaching the black box level of newer instrumentation while maintaining the flexibility and abilities of isotope ratio mass spectrometry. This presentation will outline changes in IRMS technology applicable to the Oil & Gas industry, discuss the feasibility of true 'field' deployability and present results from a range of Oil & Gas samples.

  20. Secular variation in carbon isotope ratios from Upper Proterozoic successions of Svalbard and East Greenland.

    PubMed

    Knoll, A H; Hayes, J M; Kaufman, A J; Swett, K; Lambert, I B

    1986-06-26

    Analyses of stratigraphically continuous suites of samples from Upper Proterozoic sedimentary successions of East Greenland, Spitsbergen and Nordaustlandet (Svalbard) provide an approximation to the secular variation in carbon isotope ratios during a geologically and biologically important period of change from around 900 million years ago to the beginning of the Cambrian period. Late Riphean carbonates and organic material show a stratigraphically useful pattern of enrichment in 13C relative to Phanerozoic or earlier Proterozoic samples. Isotopic compositions of isolated samples from other localities are consistent with a worldwide extended interval of enhanced organic burial and consequent net survival of oxidized material, probably O2, just before the initial radiation of metazoans.

  1. Bayesian Integration of Isotope Ratio for Geographic Sourcing of Castor Beans

    PubMed Central

    Webb-Robertson, Bobbie-Jo; Kreuzer, Helen; Hart, Garret; Ehleringer, James; West, Jason; Gill, Gary; Duckworth, Douglas

    2012-01-01

    Recent years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based on the integrated model with a class accuracy of 60.9 ± 2.1% versus 55.9 ± 2.1% and 40.2 ± 1.8% for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model. PMID:22919270

  2. Bayesian integration of isotope ratio for geographic sourcing of castor beans.

    PubMed

    Webb-Robertson, Bobbie-Jo; Kreuzer, Helen; Hart, Garret; Ehleringer, James; West, Jason; Gill, Gary; Duckworth, Douglas

    2012-01-01

    Recent years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based on the integrated model with a class accuracy of 60.9 ± 2.1% versus 55.9 ± 2.1% and 40.2 ± 1.8% for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model.

  3. Bayesian Integration of Isotope Ratio for Geographic Sourcing of Castor Beans

    DOE PAGES

    Webb-Robertson, Bobbie-Jo; Kreuzer, Helen; Hart, Garret; ...

    2012-01-01

    Recenmore » t years have seen an increase in the forensic interest associated with the poison ricin, which is extracted from the seeds of the Ricinus communis plant. Both light element (C, N, O, and H) and strontium (Sr) isotope ratios have previously been used to associate organic material with geographic regions of origin. We present a Bayesian integration methodology that can more accurately predict the region of origin for a castor bean than individual models developed independently for light element stable isotopes or Sr isotope ratios. Our results demonstrate a clear improvement in the ability to correctly classify regions based on the integrated model with a class accuracy of 60.9 ± 2.1 % versus 55.9 ± 2.1 % and 40.2 ± 1.8 % for the light element and strontium (Sr) isotope ratios, respectively. In addition, we show graphically the strengths and weaknesses of each dataset in respect to class prediction and how the integration of these datasets strengthens the overall model.« less

  4. Canopy photosynthesis estimated from sapflux and stable carbon isotope ratios in northern Idaho

    NASA Astrophysics Data System (ADS)

    Marshall, J. D.; Ubierna, N.; Kavanagh, K.; Pangle, R.; Powers, E.

    2008-12-01

    Canopy-scale estimates of photosynthesis have traditionally required either scaling up from a sample of leaf measurements or scaling down from eddy flux measurements contaminated by opposing carbon dioxide fluxes. We propose an alternative based on transpiration estimates using the well established Granier sapflux sensor and scaled by modifications of standard measurements of forest structure. The resulting sapflux estimates are converted to carbon uptake measurements by first estimating canopy conductance and then using stable carbon isotope ratios to estimate the ratio of carbon to water exchange. Carbon isotope ratios were measured on leaf bulk material, phloem contents, and the highly concentrated stem CO2 pool. As found elsewhere, leaves were highly depleted and did not provide adequate estimates. We used transfer conductances estimated in other work to adjust the carbon isotope ratios prior to estimating carbon-water exchange ratios. The resulting estimates were 11 Mg C ha-1 yr-1, well within the range to be expected based on net primar production (3.6 Mg C ha-1 yr-1) in these stands. We observed seasonal variation caused by both canopy conductance and changes in \\d13C. This method of estimating canopy photosynthesis provides an important test of one of the key, and hitherto poorly constrained, components of carbon budget analyses.

  5. Simultaneous measurement of CO2 concentration and isotopic ratios in gas samples using IRMS

    NASA Astrophysics Data System (ADS)

    Yu, Eun-Ji; Lee, Dongho; Bong, Yeon-Sik; Lee, Kwang-Sik

    2014-05-01

    Isotopic methods are indispensable tools for studies on atmosphere-biosphere exchanges of CO2 and environmental monitoring such as CO2 leakage detection from subsurface carbon storages. CO2 concentration is an important variable in interpreting isotopic composition of CO2 especially in atmospheric applications (e.g., 'Keeling plot'). Optical methods such as CRDS (Cavity Ring Down Spectroscopy) are gaining attention recently because of its capability to simultaneously measure CO2 concentration and isotopic ratios with a short measurement interval (up to 1 sec.). On the other hand, IRMS (Isotope Ratio Mass Spectrometer) has been used only for isotopic measurements. In this study, we propose a method to measure CO2 concentration from gas samples along with isotopic ratios using conventional IRMS system. The system consists of Delta V Plus IRMS interfaced with GasBench II (Thermo Scientific, Germany). 12-mL vials with open top screw cap and rubber septum were used for both gas sampling and analysis. For isotopic analysis, gases in the vials were transferred into GasBench II by He carrier flow and CO2 was trapped by a single cryotrap (-180 ºC) after passing a water trap (Mg(ClO4)2). Upon release of the cryotrap, liberated CO2 was separated from N2O using gas chromatography column inside the GasBench II and introduced online into the IRMS. Isotopic ratios were measured for the masses of 44, 45 and 46, and the peak intensity (mV of mass 44 and peak area) was recorded for the concentration calculation. For the determination of CO2 concentration, a calibration curve relating the peak intensity with molar concentration of CO2 was constructed. By dissolving NaHCO3 in de-ionized water, solutions containing 0.05, 0.1, 0.25 and 0.5 µmol of inorganic carbon were prepared in 12 mL vials. Phosphoric acid was injected through rubber septum of the vials to acidify the solution and released CO2 was analyzed for the isotopic ratios and the corresponding peak intensity was recorded

  6. Isotope-ratio-monitoring gas chromatography-mass spectrometry: methods for isotopic calibration

    NASA Technical Reports Server (NTRS)

    Merritt, D. A.; Brand, W. A.; Hayes, J. M.

    1994-01-01

    In trial analyses of a series of n-alkanes, precise determinations of 13C contents were based on isotopic standards introduced by five different techniques and results were compared. Specifically, organic-compound standards were coinjected with the analytes and carried through chromatography and combustion with them; or CO2 was supplied from a conventional inlet and mixed with the analyte in the ion source, or CO2 was supplied from an auxiliary mixing volume and transmitted to the source without interruption of the analyte stream. Additionally, two techniques were investigated in which the analyte stream was diverted and CO2 standards were placed on a near-zero background. All methods provided accurate results. Where applicable, methods not involving interruption of the analyte stream provided the highest performance (sigma = 0.00006 at.% 13C or 0.06% for 250 pmol C as CO2 reaching the ion source), but great care was required. Techniques involving diversion of the analyte stream were immune to interference from coeluting sample components and still provided high precision (0.0001 < or = sigma < or = 0.0002 at.% or 0.1 < or = sigma < or = 0.2%).

  7. Geospatial modeling of plant stable isotope ratios - the development of isoscapes

    NASA Astrophysics Data System (ADS)

    West, J. B.; Ehleringer, J. R.; Hurley, J. M.; Cerling, T. E.

    2007-12-01

    Large-scale spatial variation in stable isotope ratios can yield critical insights into the spatio-temporal dynamics of biogeochemical cycles, animal movements, and shifts in climate, as well as anthropogenic activities such as commerce, resource utilization, and forensic investigation. Interpreting these signals requires that we understand and model the variation. We report progress in our development of plant stable isotope ratio landscapes (isoscapes). Our approach utilizes a GIS, gridded datasets, a range of modeling approaches, and spatially distributed observations. We synthesize findings from four studies to illustrate the general utility of the approach, its ability to represent observed spatio-temporal variability in plant stable isotope ratios, and also outline some specific areas of uncertainty. We also address two basic, but critical questions central to our ability to model plant stable isotope ratios using this approach: 1. Do the continuous precipitation isotope ratio grids represent reasonable proxies for plant source water?, and 2. Do continuous climate grids (as is or modified) represent a reasonable proxy for the climate experienced by plants? Plant components modeled include leaf water, grape water (extracted from wine), bulk leaf material ( Cannabis sativa; marijuana), and seed oil ( Ricinus communis; castor bean). Our approaches to modeling the isotope ratios of these components varied from highly sophisticated process models to simple one-step fractionation models to regression approaches. The leaf water isosocapes were produced using steady-state models of enrichment and continuous grids of annual average precipitation isotope ratios and climate. These were compared to other modeling efforts, as well as a relatively sparse, but geographically distributed dataset from the literature. The latitudinal distributions and global averages compared favorably to other modeling efforts and the observational data compared well to model predictions

  8. Osmium-isotope ratios of platinum-group minerals associated with ultramafic intrusions: Os-isotopic evolution of the oceanic mantle

    NASA Astrophysics Data System (ADS)

    Hattori, Keiko; Hart, Stanley R.

    1991-12-01

    Osmium-isotope ratios were determined by an ion microprobe on the individual platinum-group minerals (PGM) from placers, which are associated with ultramafic intrusions of late Precambrian to Tertiary age. Unlike Os-isotope ratios in large layered mafic intrusions, these 187Os/ 186Os ratios are low, and within a narrow range from 0.99 to 1.12, which is attributed to the occurrences of the intrusions. There was no opportunity to incorporate old crustal Os because of the small sizes of the intrusions and the mode of emplacement into the upper crustal level. In addition, the interaction with the host volcanic rocks of similar age, if any, would not have seriously affected the 187Os/ 86Os ratios of the peridotites. While different phases of PGM in one grain have similar 187Os/ 186Os ratios, there is a significant variation in a given district. The variation is attributed to a long-term heterogeneity in Re/Os ratios of the oceanic upper mantle. The lowest value in each area is lower than the value expected from the evolution of bulk Earth composition. The lowering may be due to primordially low Re/Os ratios in the mantle or preferential removal of Re by partial melting to form the continental crust. The former model is rejected because most chondrites have higher Re/Os ratios than type C1 and the core-mantle separation would not have lowered Re/Os ratios. The low 187Os/ 186Os ratios are, therefore attributed to the extraction of continental crust by preferential removal of Re from the mantle through partial melting. The model is consistent with the depleted nature of oceanic peridotites (positive ɛ Nd, negative ɛ Sr, and low Re/Os ratios). Calculations of 187Os/ 186Os ratios of the mantle residue suggest that the observed data are in accordance with a model involving the extraction of ˜ 2% melt by fractional fusion from the mantle of C1 chondritic composition at ˜ 2.0 Ga. If the bulk Earth has higher Re/Os ratios, as proposed by Martin [1], then the observed data

  9. Along-strike magma mixing beneath mid-ocean ridges - Effects on isotopic ratios

    NASA Technical Reports Server (NTRS)

    Kenyon, P. M.; Turcotte, D. L.

    1987-01-01

    The effects of mixing processes on the isotopic variability of midocean ridge basalts are studied. The processes considered are porous flow dispersion and convective mixing in magma chambers. Porous flow dispersion is capable of mixing magmas over distances of only a few tens of meters. Convective mixing, on the other hand, is found to produce continuous magma chambers, where mixing is limited by convective processes, and for discontinuous chambers, where mixing is limited by chamber size. Preliminary comparison of the calculations with observations along the midocean ridges shows that the calculations are consistent with the existence of a correlation between bathymetry and isotopic ratio at long, but not at short, wavelengths. They are also capable of explaining a decrease in isotopic variability with increasing spreading rate.

  10. Performance and limits of liquid chromatography isotope ratio mass spectrometry system for halogenated compounds

    NASA Astrophysics Data System (ADS)

    Gilevska, Tetyana; Gehre, Matthias; Richnow, Hans

    2014-05-01

    Compound Specific Isotope Analysis (CSIA) has been an important step for the assessment of the origin and fate of compounds in environmental science.[1] Biologically or pharmaceutically important compounds often are not amenable for gas chromatographic separation because of high polarity and lacking volatility, thermostability. In 2004 liquid chromatography isotope ratio mass spectrometry (LC-IRMS) became commercially available. LC-IRMS system intent a quantitative conversion of analytes separation into CO2 via wet oxidation with sodium persulfate in the presence of phosphoric acid while analytes are still dissolved in the aqueous liquid phase.[2] The aim of this study is to analyze the oxidation capacity of the interface of the LC-IRMS system and determine which parameters could improve oxidation of compounds which are resistant to persulfate oxidation. Oxidation capacity of the liquid chromatography isotope ratio mass spectrometry system was tested with halogenated acetic acid and a set of aromatic compounds with different substitutes. Acetic acid (AA) was taken as a model compound for complete oxidation and compared to the oxidation of other analytes on a molar basis. Correct values were obtained for di- and mono chlorinated and fluorinated and also for tribrominated acetic acid and for all studied aromatic compounds. Incomplete oxidation for trichloroacetic (TCAA) and trifluoroacetic (TFAA) acid was revealed with lower recovery compared to acetic acid and isotope fractionation leading to depleted carbon isotope composition compared to values obtained with an elementary analyzer connected to an isotope mass spectrometer Several optimization steps were tried in order to improve the oxidation of TCAA and TFAA: (i) increasing the concentration of the oxidizing agent, (ii) variation of flow rate of the oxidizing and acid solution, (iii) variation of flow rate of liquid chromatography pump (iv) addition of a catalyzer. These modifications lead to longer reaction time

  11. The Effect of Aerosol Formation on Stable Isotopes Ratio in Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Gautier, Thomas; Trainer, Melissa G.; Sebree, Joshua; Wold, Allison; Stern, Jennifer

    2016-10-01

    The formation of large amounts of aerosol in Titan atmosphere induces a significant sink for carbon and nitrogen in the atmosphere. Due to the high complexity of the chemistry leading to aerosol formation, there may be isotopic fractionation along the formation pathways of the aerosol. So far several stable isotopes have been measured in Titan atmosphere including the 13C/12C, 15N/14N and D/H ratios for different gaseous species. However, the fractionation effect of the aerosol formation and its impact on atmospheric stable isotope ratios has yet to be fully understood. Two experimental studies were recently published on the stable carbon [1] and nitrogen [1,2] isotope fractionation during aerosol formation in N2-CH4 reactant mixture. To better constrain the fractionation effect of aerosol formation on the Titan atmosphere we have measured the isotopic fractionation induced in laboratory aerosol analogues produced exploring the space of parameters that are expected to have an effect on fractionation processes. Parameters studied include pressure and temperature of aerosol formation and the reactant gas phase composition, including the standard "Titan" mixture of CH4/N2 as well as other trace species such as benzene (C6H6).[1] Sebree, J.A., Stern, J.C., Mandt, K.E., Domagal-Goldman, S.D., and Trainer, M.G.: C and N Fractionation of CH /N Mixtures during Photochemical Aerosol Formation: Relevance to Titan, (2016) Icarus 270:421-428[2] Kuga, M., Carrasco, N., Marty, B., Marrochi, Y., Bernard, S., Rigaudier, T., Fleury, B., Tissandier, L.: Nitrogen isotopic fractionation during abiotic synthesis of organic solid particles, (2014) EPSL 393:2-13

  12. Advances in Instrumentation for Quantification of Isotopic Nitrous Oxide from ppb levels to 100%

    NASA Astrophysics Data System (ADS)

    Dong, F.; Gupta, M.; Leen, J.; Provencal, R. A.; Owano, T. G.; Baer, D. S.

    2013-12-01

    The isotopic composition of trace gases provides information of their origin and fate that cannot be determined from their concentration measurements alone. Biological source and loss processes, like bacterial production of nitrous oxide, are typically accompanied by isotopic selectivity associated with the kinetics of bond formation and destruction. Of the three important biologically mediated greenhouse gases (CO2, CH4 and N2O), the understanding of nitrous oxide isotopic budget in air lags behind the other two gases primarily due to the relatively low concentration of N2O in ambient air (~320 ppb). Furthermore, the origin of nitrates in rivers, lakes, ocean and other water supplies may be determined from analyses of isotopic nitrous oxide produced via chemical reduction or biological conversion. These processes can produce nitrous oxide at levels considerably greater than those present in ambient air. To date, analyses of isotopic nitrous oxide requires either pre-concentration of samples containing low concentrations or dilution of samples with high concentrations. We report significant advances of instrumentation for real-time measurements of site-specific isotopic nitrogen (δ15Nα, δ15Nβ, δ15N, δ18O) and mixing ratio [N2O] of nitrous oxide over a very wide range of mole fractions in air. Specifically, LGR's Isotopic N2O Analyzer can report site-specific isotopic nitrogen and isotopic oxygen continuously in flows ranging from 0.2 to over 20 ppm (parts per million) nitrous oxide in air (with preconcentration or dilution). Furthermore, for samples of limited volume, a batch technique may be used for similar isotopic measurements in discrete samples containing 0.2 ppm to 100% nitrous oxide (e.g., sample volumes from bacterial digestion can be as little as 1-10 mL). This novel technology, which employs cavity enhanced absorption spectroscopy (Off-Axis ICOS) and a mid-infrared laser (4.56 microns) and does not require any cryogenic components, has been

  13. Nitrogen-isotope ratios of nitrate in ground water under fertilized fields, Long Island, New York

    USGS Publications Warehouse

    Flipse, W.J.; Bonner, F.T.

    1985-01-01

    Ground-water samples from two heavily fertilized sites in Suffolk County, New York, were collected through the 1978 growing season and analyzed for nitrate-N concentrations and nitrogen-isotope ratios. Six wells were at a potato farm; six were on a golf course. The purpose of this study was to determine whether the 15N/14N ratios (??15N values) of fertilizer are increased during transit from land surface to ground water to an extent which would preclude use of this ratio to distinguish agricultural from animal sources of nitrate in ground water. Ground water at both sites contained a greater proportion of 15N than the fertilizers being applied. At the potato farm, the average ??15N value of the fertilizers was 0.2???; the average ??15N value of the ground-water nitrate was 6.2???. At the golf course, the average ??15N value of the fertilizers was -5.9???, and that of ground-water nitrate was 6.5???. The higher ??15N values of ground-water nitrate are probably caused by isotopic fractionation during the volatile loss of ammonia from nitrogen applied in reduced forms (NH4+ and organic-N). The ??15N values of most ground-water samples from both areas were less than 10???, the upper limit of the range characteristic of agricultural sources of nitrate; these sources include both fertilizer nitrate and nitrate derived from increased mineralization of soil nitrogen through cultivation. Previous studies have shown that the ??15N values of nitrate derived from human or animal waste generally exceed 10???. The nitrogen-isotope ratios of fertilizer-derived nitrate were not altered to an extent that would make them indistinguishable from animal-waste-derived nitrates in ground water.Ground-water samples from two heavily fertilized sites in Suffolk County, New York, were collected through the 1978 growing season and analyzed for nitrate-N concentrations and nitrogen-isotope ratios. Six wells were at a potato farm; six were on a golf course. The purpose of this study was to

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

    NASA Astrophysics Data System (ADS)

    Fujiya, Wataru; Hoppe, Peter; Ott, Ulrich

    2016-09-01

    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.

  15. The fractionation factors of stable carbon and hydrogen isotope ratios for VOCs

    NASA Astrophysics Data System (ADS)

    Kawashima, H.

    2014-12-01

    Volatile organic compounds (VOCs) are important precursors of ozone and secondary organic aerosols in the atmosphere, some of which are carcinogenic, teratogenic, or mutagenic. VOCs in ambient air originate from many sources, including vehicle exhausts, gasoline evaporation, solvent use, natural gas emissions, and industrial processes, and undergo intricate chemical reactions in the atmosphere. To develop efficient air pollution remediation strategies, it is important to clearly identify the emission sources and elucidate the reaction mechanisms in the atmosphere. Recently, stable carbon isotope ratios (δ13C) of VOCs in some sources and ambient air have been measured by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). In this study, we measured δ13C and stable hydrogen isotope ratios (δD) of atmospheric VOCs by using the gas chromatography/thermal conversion/isotope ratio mass spectrometry coupled with a thermal desorption instrument (TD-GC/TC/IRMS). The wider δD differences between sources were found in comparison with the δ13C studies. Therefore, determining δD values of VOCs in ambient air is potentially useful in identifying VOC sources and their reactive behavior in the atmosphere. However, to elucidate the sources and behavior of atmospheric VOCs more accurately, isotopic fractionation during atmospheric reaction must be considered. In this study, we determined isotopic fractionation of the δ13C and δD values for the atmospheric some VOCs under irradiation conditions. As the results, δ13C for target all VOCs and δD for most VOCs were increasing after irradiation. But, the δD values for both benzene and toluene tended to decrease as irradiation time increased. We also estimated the fractionation factors for benzene and toluene, 1.27 and 1.05, respectively, which differed from values determined in previous studies. In summary, we were able to identify an inverse isotope effect for the δD values of benzene and toluene

  16. Forensic utility of carbon isotope ratio variations in PVC tape backings.

    PubMed

    Dietz, Marianne E; Stern, Libby A; Mehltretter, Andria Hobbs; Parish, Ashley; McLasky, Velvet; Aranda, Roman

    2012-03-01

    Forensic interest in adhesive tapes with polyvinyl chloride (PVC) backings (electrical tape) derives from their use in a variety of illicit activities. Due to the range of physical characteristics, chemical compositions, and homogeneity within a single roll of tape, traditional microscopic and chemical analyses can offer a high degree of discrimination between tapes, permitting the assessment of potential associations between evidentiary tape samples. The carbon isotope ratios of tapes could provide additional discrimination among tape samples. To evaluate whether carbon isotope ratios may be able to increase discrimination of electrical tapes, particularly with regards to different rolls of tape of the same product, we assessed the δ(13)C values of backings from 87 rolls of PVC-based black electrical tape (~20 brands, >60 products) Prior to analysis, adhesives were removed to prevent contamination by adhering debris, and plasticizers were extracted because of concern over their potential mobility. This result is consistent with each of these tapes having approximately the same plasticizer δ(13)C value and proportion of carbon in these plasticizers. The δ(13)C values of the 87 PVC tape backings ranged between -23.5 and -41.3 (‰, V-PDB), with negligible carbon isotopic variation within single rolls of tape, yet large variations among tape brands and tape products. Within this tape population, carbon isotope ratios permitted an average exclusion power of 93.7%, using a window of +/-0.3‰; the combination of carbon isotope ratio measurement with additional chemical and physical analyses raises the discrimination power to over 98.9%, with only 41 out of a possible 3741 pairs of tape samples being indistinguishable. There was a linear relationship between the δ(13)C value of tape backings and the change in δ(13)C value with the extraction of plasticizers. Analyses of pre- and post-blast tape sample pairs show that carbon isotope signatures are within 0.3‰ of

  17. S Isotope Ratios of Central Italy Waters to Assess Their Origin

    NASA Astrophysics Data System (ADS)

    Castorina, Francesca; Masi, Umberto

    2010-05-01

    Sr isotopes have so far applied only occasionally to the study of the waters from central Italy. Therefore, we have analyzed more than 30 water samples from thermal and cold springs, and from the lakes located in the Quaternary K-alkaline volcanic districts of Latium, aimed at providing significant information on the sources of Sr and the hydrologic circulation. The 87Sr/86Sr composition of the waters shows a general correlation with the aquifer rocks, resulting in the waters from older carbonatic rocks having a less radiogenic signature than those from younger K-alkaline volcanic rocks. The Sr-isotope ratios of most thermal waters range narrowly by 0.708, indicating a common source of Sr, likely represented by the Upper Triassic Burano Anhydrites, i.e. the lowermost permeable formation in the study area. Moreover, the positive correlation between Sr and Ca suggests that bulk Ca was also supplied from that source. A minor number of thermal waters as well as all the waters from the lakes and cold springs display a larger Sr isotopic range (0.7085-0.7115), suggesting a relative large spectrum of sources for Sr. In particular, some waters derive their Sr from a singular source, but the most show isotopic signatures suggestive of mixed contributions from different aquifers. As a whole, the results from this study confirm that Sr isotopes are a useful tool contributing to explain the geochemical characteristics of surficial and groundwaters.

  18. Measurement of Sulfur Isotope Ratios in Micrometer-Sized Aerosol Samples by NanoSIMS

    NASA Astrophysics Data System (ADS)

    Winterholler, B.; Hoppe, P.; Foley, S.; Andreae, M. O.

    2005-12-01

    The isotopic composition of sulfur in the atmosphere is highly variable and source dependent. Sulfur isotopic ratios are a well established tool for identifying sources of sulfur in the environment, estimating emission factors, and tracing the spread of sulfur from anthropogenic point sources in terrestrial ecosystems. Conventional mass spectrometry needs a minimum of 1 micromol of sulfur to perform one analysis. In the case of atmospheric aerosol particles the results of such an analysis averages the isotopic compositions of millions of aerosol particles, and thus normally includes several different types of sulfur aerosol. The new Cameca NanoSIMS 50 ion microprobe technique permits analysis of individual aerosol particles with volumes down to 0.3 cubic micron and a precision for delta34S of 3-10 (2 sigma). As a result, this technique is able to introduce a new scale into the study of the atmospheric sulfur cycle. Linking the chemical, mineralogical, morphological and isotopic information of individual particles will allow a better understanding of external and internal mixing states by analyzing more than one spot on coarse mode particles. Moreover it will improve source identification by complementing the chemical and isotopic information. First samples have been collected from the Sahara desert, an urban site in central Europe, and a costal site in Western Ireland and show the potentials of this new technique.

  19. Stable isotope ratios as indicators of trophic status: Uncertainties imposed by geographic effects

    SciTech Connect

    Schell, D.M.

    1995-12-31

    Isotope ratios of carbon and nitrogen are often suggested as indicators to determine trophic status and carbon sources of marine organisms in explaining relative concentrations of pollutants. Whereas this technique is effective with organisms resident in ecosystems having homogeneous primary productivity regimes and uniform isotope ratios in the productivity base, it often is confounded by migratory movements by larger organisms across isotopic gradients. Tissues containing a temporal record such as baleen plates or whiskers show these effects clearly. Bowhead whales in Alaskan waters seasonally move across carbon isotope gradients of 5{per_thousand} in zooplankton and reflect these differences in the keratin of baleen plates and in overall body composition. However, no significant differences in {delta}{sup 15}N are evident regionally in northern Alaskan zooplankton. In contrast, the Southern Ocean is characterized by extreme latitudinal gradients in both {delta}{sup 13}C and {delta}{sup 15}N with the most pronounced effects occurring at the subtropical convergence. Prey taken by marine mammals south of this zone are depleted in both {sup 15}N and {sup 13}C by up to 8{per_thousand}. Data on southern right whales (Eubalaena glacialis), Bryde`s whale (Balaenoptera edenl), pygmy right whales (Caperea marginate) and antarctic fur seal (Arctocephalos gazella) show the effects of migratory movements across the gradient in both carbon and nitrogen isotope ratios. Similar patterns in marine mammal tissues from Australia, South Africa and South America indicate that the observed patterns are circumpolar. Within a given region, trophic effects shift {delta}{sup 15}N values consistent with observed feeding habits.

  20. Flow injection analysis-isotope ratio mass spectrometry for bulk carbon stable isotope analysis of alcoholic beverages.

    PubMed

    Jochmann, Maik A; Steinmann, Dirk; Stephan, Manuel; Schmidt, Torsten C

    2009-11-25

    A new method for bulk carbon isotope ratio determination of water-soluble samples is presented that is based on flow injection analysis-isotope ratio mass spectrometry (FIA-IRMS) using an LC IsoLink interface. Advantages of the method are that (i) only very small amounts of sample are required (2-5 microL of the sample for up to 200 possible injections), (ii) it avoids complex sample preparation procedures such as needed for EA-IRMS analysis (only sample dilution and injection,) and (iii) high throughput due to short analysis times is possible (approximately 15 min for five replicates). The method was first tested and evaluated as a fast screening method with industrially produced ethanol samples, and additionally the applicability was tested by the measurement of 81 alcoholic beverages, for example, whiskey, brandy, vodka, tequila, and others. The minimal sample concentration required for precise and reproducible measurements was around 50 microL L(-1) ethanol/water (1.71 mM carbon). The limit of repeatability was determined to be r=0.49%. FIA-IRMS represents a fast screening method for beverage authenticity control. Due to this, samples can be prescreened as a decisive criterion for more detailed investigations by HPLC-IRMS or multielement GC-IRMS measurements for a verification of adulteration.

  1. Concentrations of iodine isotopes ((129)I and (127)I) and their isotopic ratios in aerosol samples from Northern Germany.

    PubMed

    Daraoui, A; Riebe, B; Walther, C; Wershofen, H; Schlosser, C; Vockenhuber, C; Synal, H-A

    2016-04-01

    New data about (129)I, (127)I concentrations and their isotopic ratios in aerosol samples from the trace survey station of the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Northern Germany, are presented and discussed in this paper. The investigated samples were collected on a weekly basis during the years 2011 to 2013. Iodine was extracted from aerosol filters using a strong basic solution and was separated from the matrix elements with chloroform and was analysed by accelerator mass spectrometry (AMS) for (129)I and by inductively coupled plasma mass spectrometry (ICP-MS) for (127)I. The concentrations of (127)I and (129)I in aerosol filters ranged from 0.31 to 3.71 ng m(-3) and from 0.06 to 0.75 fg m(-3), respectively. The results of (129)I/(127)I isotopic ratios were in the order 10(-8) to 10(-7). The (129)I originated directly from gaseous emissions and indirectly from liquid emissions (via sea spray) from the reprocessing plants in Sellafield and La Hague. In comparison with the results of (131)I after the Fukushima accident, no contribution of (129)I from this accident was detectable in Central Europe due to the high background originating from the (129)I releases of the European reprocessing plants. (129)I atmospheric activity concentrations were compared with those of an anthropogenic radionuclide ((85)Kr). We did not find any correlation between (129)I and (85)Kr, both having nuclear reprocessing plant as the main source.

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  3. Carbon isotope ratio monitoring-gas chromatography mass spectrometric measurements in the marine environment: biomarker sources and paleoclimate applications.

    PubMed

    Tolosa, I; Lopez, J F; Bentaleb, I; Fontugne, M; Grimalt, J O

    1999-09-30

    Some applications in the use of compound-specific isotopic analyses (CSIA) for biomarker source elucidation in the marine environment and its potential applications to paleoclimatology are evaluated in the present study. The potential use of the carbon isotope ratios of marine biomarkers as recorders of CO2 levels has been considered. A significant correlation between delta 13C cholesterol of suspended particulates and seawater CO2 concentrations from the south Indian Ocean has been found. delta 13C composition in biomarkers of different functionalities from three photosynthetic organisms has been examined. Small variations within and between biosynthetically related compound classes have been observed in cyanobacteria. In algae, e.g. diatoms and dinoflagellates, significant differences between the average delta 13C composition of fatty acids and sterols were observed (7.5/1000 and 2/1000, respectively). These differences can be attributed to diverse isotope effects associated with different biosynthetic reactions. Isotopic variations among homologues of the same lipid class have also been observed. In diatoms, variations were up to 5/1000 within each class of fatty acids and sterols and in the dinoflagellate species, these variations were lower than 3/1000. These differences, and particularly the intra-specific shifts in delta 13C lipid composition, must be considered for the correct interpretation of changes in delta 13C molecular signatures in the marine environment.

  4. Potential uses of stable isotope ratios of Sr, Nd, and Pb in geological materials for environmental studies.

    PubMed

    Nakano, Takanori

    2016-01-01

    The ratios of stable isotopes of certain elements in rocks and minerals have strong regional characteristics that are reflected in atmospheric components, in water, and in the living organisms that form Earth's surface environment as well as in agricultural and fishery products. Geologically derived stable isotope ratios can be used as a tracer for the source of many kinds of substances, with current geochemical techniques allowing the precise determination of numerous stable isotope ratios in both natural and manmade objects. This review presents examples of the use of stable isotopes as tracers within diverse dynamic ecosystems, focusing on Sr isotopes but also including examples of Nd and Pb isotopic analysis, and reviewing the potential of this technique for a wide range of environmental research, including determining the geographic origin of food and archeological materials.

  5. Potential uses of stable isotope ratios of Sr, Nd, and Pb in geological materials for environmental studies

    PubMed Central

    NAKANO, Takanori

    2016-01-01

    The ratios of stable isotopes of certain elements in rocks and minerals have strong regional characteristics that are reflected in atmospheric components, in water, and in the living organisms that form Earth’s surface environment as well as in agricultural and fishery products. Geologically derived stable isotope ratios can be used as a tracer for the source of many kinds of substances, with current geochemical techniques allowing the precise determination of numerous stable isotope ratios in both natural and manmade objects. This review presents examples of the use of stable isotopes as tracers within diverse dynamic ecosystems, focusing on Sr isotopes but also including examples of Nd and Pb isotopic analysis, and reviewing the potential of this technique for a wide range of environmental research, including determining the geographic origin of food and archeological materials. PMID:27302069

  6. Laser ablation inductively coupled plasma mass spectrometry measurement of isotope ratios in depleted uranium contaminated soils.

    PubMed

    Seltzer, Michael D

    2003-09-01

    Laser ablation of pressed soil pellets was examined as a means of direct sample introduction to enable inductively coupled plasma mass spectrometry (ICP-MS) screening of soils for residual depleted uranium (DU) contamination. Differentiation between depleted uranium, an anthropogenic contaminant, and naturally occurring uranium was accomplished on the basis of measured 235U/238U isotope ratios. The amount of sample preparation required for laser ablation is considerably less than that typically required for aqueous sample introduction. The amount of hazardous laboratory waste generated is diminished accordingly. During the present investigation, 235U/238U isotope ratios measured for field samples were in good agreement with those derived from gamma spectrometry measurements. However, substantial compensation was required to mitigate the effects of impaired pulse counting attributed to sample inhomogeneity and sporadic introduction of uranium analyte into the plasma.

  7. Determination of tin isotope ratios in cassiterite by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schulze, Marie; Ziegerick, Marco; Horn, Ingo; Weyer, Stefan; Vogt, Carla

    2017-04-01

    In comparison to isotope analysis of dissolved samples femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS) enables precise isotope ratio analyses consuming much less sample material and with a minimum effort in sample preparation. This is especially important for the investigation of valuable historical objects for which visual traces of sampling are unwanted. The present study provides a basis for tin isotope ratio measurements using LA-MC-ICP-MS technique. For this, in house isotope standards had to be defined. Investigations on interferences and matrix effects illustrate that beside Sb only high Te contents (with values above those to be expected in cassiterite) result in a significant shift of the measured tin isotope ratios. This effect can partly be corrected for using natural isotope abundances. However, a natural isotope fractionation of Te cannot be excluded. Tin beads reduced from cassiterite were analysed by laser ablation and after dissolution. It was shown that tin isotope ratios can be determined accurately by using fs-LA-MC-ICP-MS. Furthermore the homogeneity of tin isotope ratios in cassiterite was proven.

  8. Advancement and application of gas chromatography isotope ratio mass spectrometry techniques for atmospheric trace gas analysis

    NASA Astrophysics Data System (ADS)

    Giebel, Brian M.

    2011-12-01

    The use of gas chromatography isotope ratio mass spectrometry (GC-IRMS) for compound specific stable isotope analysis is an underutilized technique because of the complexity of the instrumentation and high analytical costs. However stable isotopic data, when coupled with concentration measurements, can provide additional information on a compounds production, transformation, loss, and cycling within the biosphere and atmosphere. A GC-IRMS system was developed to accurately and precisely measure delta13C values for numerous oxygenated volatile organic compounds having natural and anthropogenic sources. The OVOCs include methanol, ethanol, acetone, methyl ethyl ketone, 2-pentanone, and 3-pentanone. Guided by the requirements for analysis of trace components in air, the GC-IRMS system was developed with the goals of increasing sensitivity, reducing dead-volume and peak band broadening, optimizing combustion and water removal, and decreasing the split ratio to the IRMS. The technique relied on a two-stage preconcentration system, a low-volume capillary reactor and water trap, and a balanced reference gas delivery system. Measurements were performed on samples collected from two distinct sources (i.e. biogenic and vehicle emissions) and ambient air collected from downtown Miami and Everglades National Park. However, the instrumentation and the method have the capability to analyze a variety of source and ambient samples. The measured isotopic signatures that were obtained from source and ambient samples provide a new isotopic constraint for atmospheric chemists and can serve as a new way to evaluate their models and budgets for many OVOCs. In almost all cases, OVOCs emitted from fuel combustion were enriched in 13C when compared to the natural emissions of plants. This was particularly true for ethanol gas emitted in vehicle exhaust, which was observed to have a uniquely enriched isotopic signature that was attributed to ethanol's corn origin and use as an alternative

  9. Mixing ratio and carbon isotopic composition investigation of atmospheric CO2 in Beijing, China.

    PubMed

    Pang, Jiaping; Wen, Xuefa; Sun, Xiaomin

    2016-01-01

    The stable isotope composition of atmospheric CO2 can be used as a tracer in the study of urban carbon cycles, which are affected by anthropogenic and biogenic CO2 components. Continuous measurements of the mixing ratio and δ(13)C of atmospheric CO2 were conducted in Beijing from Nov. 15, 2012 to Mar. 8, 2014 including two heating seasons and a vegetative season. Both δ(13)C and the isotopic composition of source CO2 (δ(13)CS) were depleted in the heating seasons and enriched in the vegetative season. The diurnal variations in the CO2 mixing ratio and δ(13)C contained two peaks in the heating season, which are due to the effects of morning rush hour traffic. Seasonal and diurnal patterns of the CO2 mixing ratio and δ(13)C were affected by anthropogenic emissions and biogenic activity. Assuming that the primary CO2 sources at night (22:00-04:00) were coal and natural gas combustion during heating seasons I and II, an isotopic mass balance analysis indicated that coal combustion had average contributions of 83.83±14.11% and 86.84±12.27% and that natural gas had average contributions of 16.17±14.11% and 13.16±12.27%, respectively. The δ(13)C of background CO2 in air was the main error source in the isotopic mass balance model. Both the mixing ratio and δ(13)C of atmospheric CO2 had significant linear relationships with the air quality index (AQI) and can be used to indicate local air pollution conditions. Energy structure optimization, for example, reducing coal consumption, will improve the local air conditions in Beijing.

  10. Isotope ratio measurements by secondary ion mass spectrometry (SIMS) and glow discharge mass spectrometry (GDMS)

    NASA Astrophysics Data System (ADS)

    Betti, Maria

    2005-04-01

    The basic principles of secondary ion mass spectrometry and glow discharge mass spectrometry have been shortly revisited. The applications of both techniques as exploited for the isotope ratio measurements in several matrices have been reviewed. Emphasis has been given to research fields in expansions such as solar system studies, medicine, biology, environment and nuclear forensic. The characteristics of the two techniques are discussed in terms of sensitivity and methodology of quantification. Considerations on the different detection possibilities in SIMS are also presented.

  11. Accurate and precise determination of isotopic ratios by MC-ICP-MS: a review.

    PubMed

    Yang, Lu

    2009-01-01

    For many decades the accurate and precise determination of isotope ratios has remained a very strong interest to many researchers due to its important applications in earth, environmental, biological, archeological, and medical sciences. Traditionally, thermal ionization mass spectrometry (TIMS) has been the technique of choice for achieving the highest accuracy and precision. However, recent developments in multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) have brought a new dimension to this field. In addition to its simple and robust sample introduction, high sample throughput, and high mass resolution, the flat-topped peaks generated by this technique provide for accurate and precise determination of isotope ratios with precision reaching 0.001%, comparable to that achieved with TIMS. These features, in combination with the ability of the ICP source to ionize nearly all elements in the periodic table, have resulted in an increased use of MC-ICP-MS for such measurements in various sample matrices. To determine accurate and precise isotope ratios with MC-ICP-MS, utmost care must be exercised during sample preparation, optimization of the instrument, and mass bias corrections. Unfortunately, there are inconsistencies and errors evident in many MC-ICP-MS publications, including errors in mass bias correction models. This review examines "state-of-the-art" methodologies presented in the literature for achievement of precise and accurate determinations of isotope ratios by MC-ICP-MS. Some general rules for such accurate and precise measurements are suggested, and calculations of combined uncertainty of the data using a few common mass bias correction models are outlined.

  12. Variations in Sr and Nd isotopic ratios of mineral particles in cryoconite in western Greenland

    NASA Astrophysics Data System (ADS)

    Nagatsuka, Naoko; Takeuchi, Nozomu; Uetake, Jun; Shimada, Rigen; Onuma, Yukihiko; Tanaka, Sota; Nakano, Takanori

    2016-11-01

    In order to better understand the source of minerals on the dark-colored ice, located in the Greenland ice sheet ablation zone, we analyzed the Sr and Nd isotopic ratios of minerals in cryoconite, which were collected from glaciers in northwest and southwest Greenland. We focused on the following: (i) comparison of the isotopes of minerals in cyroconite with those in sediments from local and distant areas, (ii) regional variations in western Greenland, and (iii) spatial variations across an individual a glacier. The mineral components of the cryoconite showed variable Sr and Nd isotopic ratios (87Sr/86Sr: 0.711335 to 0.742406, ɛNd (0): -33.1 to -22.9), which corresponded to those of the englacial dust and moraine on and around the glaciers but were significantly different from those of the distant deserts that have been considered to be primary sources of mineral dust on the Greenland Ice Sheet. This suggests that the minerals within the cryoconites were mainly derived from local sediments, rather than from distant areas. The Sr ratios in the northwestern region were significantly higher than those in the southwestern region. This is probably due to geological differences in the source areas, such as the surrounding glaciers in each region. The isotopic ratios further varied spatially within a glacier (Qaanaaq and Kangerlussuaq areas), indicating that the silicate minerals on the glaciers were derived not from a single source but from multiple sources, such as englacial dust and wind-blown minerals from the moraine surrounding the glaciers.

  13. Evaluating the deep-ocean circulation of a global ocean model using carbon isotopic ratios

    NASA Astrophysics Data System (ADS)

    Paul, André; Dutkiewicz, Stephanie; Gebbie, Jake; Losch, Martin; Marchal, Olivier

    2016-04-01

    We study the sensitivity of a global three-dimensional biotic ocean carbon-cycle model to the parameterizations of gas exchange and biological productivity as well as to deep-ocean circulation strength, and we employ the carbon isotopic ratios δ13C and Δ14C of dissolved inorganic carbon for a systematic evaluation against observations. Radiocarbon (Δ14C) in particular offers the means to assess the model skill on a time scale of 100 to 1000 years relevant to the deep-ocean circulation. The carbon isotope ratios are included as tracers in the MIT general circulation model (MITgcm). The implementation involves the fractionation processes during photosynthesis and air-sea gas exchange. We present the results of sixteen simulations combining two different parameterizations of the piston velocity, two different parameterizations of biological productivity (including the effect of iron fertilization) and four different overturning rates. These simulations were first spun up to equilibrium (more than 10,000 years of model simulation) and then continued from AD 1765 to AD 2002. For the model evaluation, we followed the OCMIP-2 (Ocean Carbon-Cycle Model Intercomparision Project phase two) protocol, comparing the results to GEOSECS (Geochemical Ocean Sections Survey) and WOCE (World Ocean Circulation Experiment) δ13C and natural Δ14C data in the world ocean. The range of deep natural Δ14C (below 1000 m) for our single model (MITgcm) was smaller than for the group of different OCMIP-2 models. Furthermore, differences between different model parameterizations were smaller than for different overturning rates. We conclude that carbon isotope ratios are a useful tool to evaluate the deep-ocean circulation. Since they are also available from deep-sea sediment records, we postulate that the simulation of carbon isotope ratios in a global ocean model will aid in estimating the deep-ocean circulation and climate during present and past.

  14. A capillary absorption spectrometer for stable carbon isotope ratio (13C/12C) analysis in very small samples

    NASA Astrophysics Data System (ADS)

    Kelly, J. F.; Sams, R. L.; Blake, T. A.; Newburn, M.; Moran, J.; Alexander, M. L.; Kreuzer, H.

    2012-02-01

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO2 samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO2 near 2307 cm-1 (4.34 μm). This initial CAS system can achieve relative isotopic precision of about 10 ppm 13C, or ˜1‰ (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO2 concentrations ˜400-750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to ˜2 Torr. Overall 13C/12C ratios can be calibrated to ˜2‰ accuracy with diluted CO2 standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1000 scans are co-added in ˜10 s. The CAS is meant to work directly with converted CO2 samples from a laser ablation-catalytic combustion micro-sampler to provide 13C/12C ratios of small biological isolates currently operating with spatial resolutions ˜50 μm.

  15. Isotope 18 O 16 O Ratio Measurements of Water Vapor by use of Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Matsumi, Yutaka; Kishigami, Masahiro; Tanaka, Noriyuki; Kawasaki, Masahiro; Inoue, Gen

    1998-09-01

    We applied a photoacoustic spectroscopy technique to isotope ratio measurements of 16 O and 18 O in water-vapor samples, using a pulsed tunable dye laser pumped by a Nd:YAG laser. The fourth overtone bands (4 OH ) of water molecules near 720 nm were investigated. We identified the absorption lines of H 2 16 O and H 2 18 O in the photoacoustic spectra that we measured by using an 18 O-enriched water sample and the HITRAN database. We measured the difference in the 18 O 16 O isotope ratios for normal distilled water and Antarctic ice, using the photoacoustic method. The value obtained for the difference between the two samples is 18 O 32 16 , where the indicated deviation was a 1 value among 240-s measurements, whereas the value measured with a conventional isotope mass spectrometer was 18 O 28 2 . This method is demonstrated to have the potential of a transportable system for in situ and quick measurements of the H 2 18 O H 2 16 O ratio in the environment.

  16. Stable carbon isotope ratios in atmospheric methane and some of its sources

    NASA Technical Reports Server (NTRS)

    Tyler, Stanley C.

    1986-01-01

    Ratios of C-13/C-12 have been measured in atmospheric methane and in methane collected from sites and biota that represent potentially large sources of atmospheric methane. These include temperate marshes (about -48 percent to about -54 percent), landfills (about -51 percent to about -55 percent), and the first reported values for any species of termite (-72.8 + or - 3.1 percent for Reticulitermes tibialis and -57.3 + or - 1.6 percent for Zootermopsis angusticollis). Numbers in parentheses are delta C-13 values with respect to PDB (Peedee belemnite) carbonate. Most methane sources reported thus far are depleted in C-13 with respect to atmospheric methane (-47.0 + or - 0.3 percent). Individual sources of methane should have C-13/C-12 ratios characteristic of mechanisms of CH4 formation and consumption prior to release to the atmosphere. The mass-weighted average isotopic composition of all sources should equal the mean C-13 of atmospheric methane, corrected for a kinetic isotope effect in the OH attack of CH4. Assuming the kinetic isotope effect to be small (about -3.0 percent correction to -47.0), as in the literature, the new values given here for termite methane do not help to explain the apparent discrepancy between C-13/C-12 ratios of the known CH4 sources and that of atmospheric CH4.

  17. DoE optimization of a mercury isotope ratio determination method for environmental studies.

    PubMed

    Berni, Alex; Baschieri, Carlo; Covelli, Stefano; Emili, Andrea; Marchetti, Andrea; Manzini, Daniela; Berto, Daniela; Rampazzo, Federico

    2016-05-15

    By using the experimental design (DoE) technique, we optimized an analytical method for the determination of mercury isotope ratios by means of cold-vapor multicollector ICP-MS (CV-MC-ICP-MS) to provide absolute Hg isotopic ratio measurements with a suitable internal precision. By running 32 experiments, the influence of mercury and thallium internal standard concentrations, total measuring time and sample flow rate was evaluated. Method was optimized varying Hg concentration between 2 and 20 ng g(-1). The model finds out some correlations within the parameters affect the measurements precision and predicts suitable sample measurement precisions for Hg concentrations from 5 ng g(-1) Hg upwards. The method was successfully applied to samples of Manila clams (Ruditapes philippinarum) coming from the Marano and Grado lagoon (NE Italy), a coastal environment affected by long term mercury contamination mainly due to mining activity. Results show different extents of both mass dependent fractionation (MDF) and mass independent fractionation (MIF) phenomena in clams according to their size and sampling sites in the lagoon. The method is fit for determinations on real samples, allowing for the use of Hg isotopic ratios to study mercury biogeochemical cycles in complex ecosystems.

  18. The stability and calibration of water vapor isotope ratio measurements during long-term deployments

    NASA Astrophysics Data System (ADS)

    Bailey, A.; Noone, D.; Berkelhammer, M.; Steen-Larsen, H. C.; Sato, P.

    2015-10-01

    With the recent advent of commercial laser absorption spectrometers, field studies measuring stable isotope ratios of hydrogen and oxygen in water vapor have proliferated. These pioneering analyses have provided invaluable feedback about best strategies for optimizing instrumental accuracy, yet questions still remain about instrument performance and calibration approaches for multi-year field deployments. With clear scientific potential for using these instruments to carry out monitoring of the hydrological cycle, this study examines the long-term stability of the isotopic biases associated with three cavity-enhanced laser absorption spectrometers - calibrated with different systems and approaches - at two remote field sites: Mauna Loa Observatory, Hawaii, USA, and Greenland Environmental Observatory, Summit, Greenland. The analysis pays particular attention to the stability of measurement dependencies on water vapor concentration and also evaluates whether these so-called concentration dependences are sensitive to statistical curve-fitting choices or measurement hysteresis. The results suggest evidence of monthly-to-seasonal concentration-dependence variability - which likely stems from low signal-to-noise at the humidity-range extremes - but no long-term directional drift. At Mauna Loa, where the isotopic analyzer is calibrated by injection of liquid water standards into a vaporizer, the largest source of inaccuracy in characterizing the concentration dependence stems from an insufficient density of calibration points at low water vapor volume mixing ratios. In comparison, at Summit, the largest source of inaccuracy is measurement hysteresis associated with interactions between the reference vapor, generated by a custom dew point generator, and the sample tubing. Nevertheless, prediction errors associated with correcting the concentration dependence are small compared to total measurement uncertainty. At both sites, changes in measurement repeatability that are

  19. Fukushima Daiichi reactor source term attribution using cesium isotope ratios from contaminated environmental samples

    DOE PAGES

    Snow, Mathew S.; Snyder, Darin C.; Delmore, James E.

    2016-01-18

    Source term attribution of environmental contamination following the Fukushima Daiichi Nuclear Power Plant (FDNPP) disaster is complicated by a large number of possible similar emission source terms (e.g. FDNPP reactor cores 1–3 and spent fuel ponds 1–4). Cesium isotopic analyses can be utilized to discriminate between environmental contamination from different FDNPP source terms and, if samples are sufficiently temporally resolved, potentially provide insights into the extent of reactor core damage at a given time. Rice, soil, mushroom, and soybean samples taken 100–250 km from the FDNPP site were dissolved using microwave digestion. Radiocesium was extracted and purified using two sequentialmore » ammonium molybdophosphate-polyacrylonitrile columns, following which 135Cs/137Cs isotope ratios were measured using thermal ionization mass spectrometry (TIMS). Results were compared with data reported previously from locations to the northwest of FDNPP and 30 km to the south of FDNPP. 135Cs/137Cs isotope ratios from samples 100–250 km to the southwest of the FDNPP site show a consistent value of 0.376 ± 0.008. 135Cs/137Cs versus 134Cs/137Cs correlation plots suggest that radiocesium to the southwest is derived from a mixture of FDNPP reactor cores 1, 2, and 3. Conclusions from the cesium isotopic data are in agreement with those derived independently based upon the event chronology combined with meteorological conditions at the time of the disaster. In conclusion, cesium isotopic analyses provide a powerful tool for source term discrimination of environmental radiocesium contamination at the FDNPP site. For higher precision source term attribution and forensic determination of the FDNPP core conditions based upon cesium, analyses of a larger number of samples from locations to the north and south of the FDNPP site (particularly time-resolved air filter samples) are needed. Published in 2016. This article is a U.S. Government work and is in the public domain

  20. Variation in trophic shift for stable isotope ratios of carbon, nitrogen, and sulfur

    USGS Publications Warehouse

    McCutchan, J.H.; Lewis, W.M.; Kendall, C.; McGrath, C.C.

    2003-01-01

    Use of stable isotope ratios to trace pathways of organic matter among consumers requires knowledge of the isotopic shift between diet and consumer. Variation in trophic shift among consumers can be substantial. For data from the published literature and supplementary original data (excluding fluid-feeding consumers), the mean isotopic shift for C was +0.5 ?? 0.13??? rather than 0.0???, as commonly assumed. The shift for C was higher for consumers analyzed as muscle (+1.3 ?? 0.30???) than for consumers analyzed whole (+0.3 ?? 0.14???). Among consumers analyzed whole, the trophic shift for C was lower for consumers acidified prior to analysis (-0.2 ?? 0.21???) than for unacidified samples (+0.5 ?? 0.17???). For N, trophic shift was lower for consumers raised on invertebrate diets (+1.4 ?? 0.21???) than for consumers raised on other high-protein diets (+3.3 ?? 0.26???) and was intermediate for consumers raised on plant and algal diets (+2.2 ?? 0.30???). The trophic shift for S differed between high-protein (+2.0 ?? 0.65???) and low-protein diets (-0.5 ?? 0.56???). Thus, methods of analysis and dietary differences can affect trophic shift for consumers; the utility of stable isotope methods can be improved if this information is incorporated into studies of trophic relationships. Although few studies of stable isotope ratios have considered variation in the trophic shift, such variation is important because small errors in estimates of trophic shift can result in large errors in estimates of the contribution of sources to consumers or in estimates of trophic position.

  1. Source Attribution of Cyanides Using Anionic Impurity Profiling, Stable Isotope Ratios, Trace Elemental Analysis and Chemometrics.

    PubMed

    Mirjankar, Nikhil S; Fraga, Carlos G; Carman, April J; Moran, James J

    2016-02-02

    Chemical attribution signatures (CAS) for chemical threat agents (CTAs), such as cyanides, are being investigated to provide an evidentiary link between CTAs and specific sources to support criminal investigations and prosecutions. Herein, stocks of KCN and NaCN were analyzed for trace anions by high performance ion chromatography (HPIC), carbon stable isotope ratio (δ(13)C) by isotope ratio mass spectrometry (IRMS), and trace elements by inductively coupled plasma optical emission spectroscopy (ICP-OES). The collected analytical data were evaluated using hierarchical cluster analysis (HCA), Fisher-ratio (F-ratio), interval partial least-squares (iPLS), genetic algorithm-based partial least-squares (GAPLS), partial least-squares discriminant analysis (PLSDA), K nearest neighbors (KNN), and support vector machines discriminant analysis (SVMDA). HCA of anion impurity profiles from multiple cyanide stocks from six reported countries of origin resulted in cyanide samples clustering into three groups, independent of the associated alkali metal (K or Na). The three groups were independently corroborated by HCA of cyanide elemental profiles and corresponded to countries each having one known solid cyanide factory: Czech Republic, Germany, and United States. Carbon stable isotope measurements resulted in two clusters: Germany and United States (the single Czech stock grouped with United States stocks). Classification errors for two validation studies using anion impurity profiles collected over five years on different instruments were as low as zero for KNN and SVMDA, demonstrating the excellent reliability associated with using anion impurities for matching a cyanide sample to its factory using our current cyanide stocks. Variable selection methods reduced errors for those classification methods having errors greater than zero; iPLS-forward selection and F-ratio typically provided the lowest errors. Finally, using anion profiles to classify cyanides to a specific stock

  2. [Sulfur isotopic ratios indicating sulfur cycling in slope soils of karst areas].

    PubMed

    Zhang, Wei; Liu, Cong-qiang; Li, Xiao-dong; Liu, Tao-ze; Zhang, Li-li

    2010-02-01

    Sequential extraction methods for soil sulfur were used to determine delta34 S ratios and sulfur contents of total sulfur, organic sulfur, SO4(21) and FeS2 in slope soils of karst areas. In general, FeS2 has the lowest delta34 S ratios, ranging from -6.86% per hundred to -4.229% per hundred, followed in ascending order by SO4(2-) (-2.64% per hundred - -1.34% per hundred), total sulfur (-3.25% per hundred - -1.03% per hundred) and organic sulfur (-1.63% per hundred -0.50% per hundred) in surface soils of profiles, and delta34 S ratios in different sulfur forms all show increasing trend with profiles deepening. Covariations of delta34 S ratios of SO4(2-) and FeS2 with increasing depth are related to SO4(2-) dissimilatory reduction, while the increase in parallel of delta34 S ratios of total sulfur and organic sulfur could be resulted from organic sulfur cycling. delta34 S ratios have been extensively used to indicate sulfur sources, moreover, SO4(2-) dissimilatory reduction and organic sulfur mineralization result in significant sulfur isotopic fractionation, and sulfides oxidation and SO4(2-) assimilation have no isotopic fractionation occurred, the vertical variations of delta34 S ratios in different sulfur forms can therefore be good records for depth-dependant sulfur cycling processes. Furthermore, by comparing depth distributions of sulfur contents and delta34 S ratios in different sulfur forms, it is easily to discuss the migration of SO4(-1) and organic sulfur fractions in soil profiles.

  3. Tap water isotope ratios reflect urban water system structure and dynamics across a semiarid metropolitan area

    NASA Astrophysics Data System (ADS)

    Jameel, Yusuf; Brewer, Simon; Good, Stephen P.; Tipple, Brett J.; Ehleringer, James R.; Bowen, Gabriel J.

    2016-08-01

    Water extraction for anthropogenic use has become a major flux in the hydrological cycle. With increasing demand for water and challenges supplying it in the face of climate change, there is a pressing need to better understand connections between human populations, climate, water extraction, water use, and its impacts. To understand these connections, we collected and analyzed stable isotopic ratios of more than 800 urban tap water samples in a series of semiannual water surveys (spring and fall, 2013-2015) across the Salt Lake Valley (SLV) of northern Utah. Consistent with previous work, we found that mean tap water had a lower 2H and 18O concentration than local precipitation, highlighting the importance of nearby montane winter precipitation as source water for the region. However, we observed strong and structured spatiotemporal variation in tap water isotopic compositions across the region which we attribute to complex distribution systems, varying water management practices and multiple sources used across the valley. Water from different sources was not used uniformly throughout the area and we identified significant correlation between water source and demographic parameters including population and income. Isotopic mass balance indicated significant interannual and intra-annual variability in water losses within the distribution network due to evaporation from surface water resources supplying the SLV. Our results demonstrate the effectiveness of isotopes as an indicator of water management strategies and climate impacts within regional urban water systems, with potential utility for monitoring, regulation, forensic, and a range of water resource research.

  4. The oxygen isotope partition function ratio of water and the structure of liquid water

    USGS Publications Warehouse

    O'Neil, J.R.; Adami, L.H.

    1969-01-01

    By means of the CO2-equilibration technique, the temperature dependence and absolute values of the oxygen isotope partition function ratio of liquid water have been determined, often at 1?? intervals, from -2 to 85??. A linear relationship between In (Q2/Q1) (H2O) and T-1 was obtained that is explicable in terms of the Bigeleisen-Mayer theory of isotopic fractionation. The data are incompatible with conventional, multicomponent mixture models of water because liquid water behaves isotopically as a singly structured homogeneous substance over the entire temperature range studied. A two-species model of water is proposed in which approximately 30% of the hydrogen bonds in ice are broken on melting at 0?? and in which this per cent of monomer changes by only a small amount over the entire liquid range. Because of the high precision and the fundamental property determined, the isotopic fractionation technique is particularly well suited to the detection of thermal anomalies. No anomalies were observed and those previously reported are ascribed to under-estimates of experimental error.

  5. Variation in oxygen isotope ratio of dissolved orthophosphate induced by uptake process in natural coral holobionts

    NASA Astrophysics Data System (ADS)

    Ferrera, Charissa M.; Miyajima, Toshihiro; Watanabe, Atsushi; Umezawa, Yu; Morimoto, Naoko; San Diego-McGlone, Maria Lourdes; Nadaoka, Kazuo

    2016-06-01

    A model incubation experiment using natural zooxanthellate corals was conducted to evaluate the influence of phosphate uptake by coral holobionts on oxygen isotope ratio of dissolved PO4 3- (δ18Op). Live coral samples of Acropora digitifera, Porites cylindrica, and Heliopora coerulea were collected from coral reefs around Ishigaki Island (Okinawa, Japan) and Bolinao (northern Luzon, Philippines) and incubated for 3-5 d after acclimatization under natural light conditions with elevated concentrations of PO4 3-. Phosphate uptake by corals behaved linearly with incubation time, with uptake rate depending on temperature. δ18Op usually increased with time toward the equilibrium value with respect to oxygen isotope exchange with ambient seawater, but sometimes became higher than equilibrium value at the end of incubation. The magnitude of the isotope effect associated with uptake depended on coral species; the greatest effect was in A. digitifera and the smallest in H. coerulea. However, it varied even within samples of a single coral species, which suggests multiple uptake processes with different isotope effects operating simultaneously with varying relative contributions in the coral holobionts used. In natural environments where concentrations of PO4 3- are much lower than those used during incubation, PO4 3- is presumably turned over much faster and the δ18Op easily altered by corals and other major primary producers. This should be taken into consideration when using δ18Op as an indicator of external PO4 3- sources in coastal ecosystems.

  6. Level structures of neutron-rich Xe isotopes

    SciTech Connect

    Ahmad, I.; Lister, C.J.; Morss, L.R.

    1995-08-01

    The level structures of neutron-rich Xe isotopes were determined by observing prompt gamma-ray coincidences in {sup 248}Cm fission fragments. A 5-mg {sup 248}Cm, in the form of {sup 248}Cm-KCl pellet, was placed inside Eurogam array which consisted of 45 Compton-suppressed Ge detectors and 5 Low-Energy Photon Spectrometers. Transitions in Xe isotopes were identified by the appearance of new peaks in the {gamma}-ray spectra obtained by gating on the gamma peaks of the complementary Mo fragments.

  7. Carbon isotope ratio (13C/12C) of pine honey and detection of HFCS adulteration.

    PubMed

    Çinar, Serap B; Ekşi, Aziz; Coşkun, İlknur

    2014-08-15

    Carbon isotope ratio ((13)C/(12)C=δ(13)C) of 100 pine honey samples collected from 9 different localities by Mugla region (Turkey) in years 2006, 2007 and 2008 were investigated. The δ(13)Cprotein value of honey samples ranged between -23.7 and -26.6‰, while the δ(13)Choney value varied between -22.7 and -27‰. For 90% of the samples, the difference in the C isotope ratio of protein and honey fraction (δ(13)Cpro-δ(13)Chon) was -1.0‰ and/or higher. Therefore, it can be said that the generally anticipated minimum value of C isotope difference (-1.0‰) for honey is also valid for pine honey. On the other hand, C4 sugar value (%), which was calculated from the δ(13)Cpro-δ(13)Chon difference, was found to be linearly correlated with the amount of adulterant (HFCS) in pine honey. These results indicate that C4 sugar value is a powerful criteria for detecting HFCS adulteration in pine honey. The δ(13)Choney and δ(13)Cprotein-δ(13)Choney values of the samples did not show any significant differences in terms of both year and locality (P>0.05), while the δ(13)Cprotein values showed significant differences due to year (P<0.05) but not due to locality (P>0.05).

  8. Development and Airborne Operation of a Compact Water Isotope Ratio Infrared Spectrometer

    NASA Technical Reports Server (NTRS)

    Iannone, Rosario Q.; Kassi, Samir; Jost, Hans-Juerg; Chenevier, Marc; Romanini, Daniele; Meijer, Harro A. J.; Dhaniyala, Suresh; Snels, Marcel; Kerstel, Erik R. T.

    2009-01-01

    A sensitive laser spectrometer, named IRIS (water isotope ratio infrared spectrometer), was developed for the in situ detection of the isotopic composition of water vapour in the upper troposphere and the lower stratosphere. Isotope ratio measurements can be used to quantify troposphere stratosphere exchange, and to study the water chemistry in the stratosphere. IRIS is based on the technique of optical feedback cavity-enhanced absorption spectroscopy. It uses a room temperature near-infrared laser, and does not require cryogenic cooling of laser or detectors. The instrument weighs 51 kg including its support structure. Airborne operation was demonstrated during three flights aboard the European M55-Geophysica stratospheric research aircraft, as part of the AMMA/SCOUT-03 (African Monsoon Multidisciplinary Analysis/Stratospheric Climate links with emphasis on the Upper Troposphere and lower stratosphere) campaign in Burkina Faso in August 2006. The data are discussed with reference to a Rayleigh distillation model. As expected, there is no indication of non-mass-dependent fractionation (also known as mass-independent fractionation) in the troposphere. Furthermore, improvements to the thermal management system and a move to a (cryogen-free) longer-wavelength laser source are discussed, which together should result in approximately two orders of magnitude improvement of the sensitivity

  9. Development and airborne operation of a compact water isotope ratio infrared spectrometer.

    PubMed

    Iannone, Rosario Q; Kassi, Samir; Jost, Hans-Jürg; Chenevier, Marc; Romanini, Daniele; Meijer, Harro A J; Dhaniyala, Suresh; Snels, Marcel; Kerstel, Erik R T

    2009-12-01

    A sensitive laser spectrometer, named IRIS (water isotope ratio infrared spectrometer), was developed for the in situ detection of the isotopic composition of water vapour in the upper troposphere and the lower stratosphere. Isotope ratio measurements can be used to quantify troposphere-stratosphere exchange, and to study the water chemistry in the stratosphere. IRIS is based on the technique of optical feedback cavity-enhanced absorption spectroscopy. It uses a room temperature near-infrared laser, and does not require cryogenic cooling of laser or detectors. The instrument weighs 51 kg including its support structure. Airborne operation was demonstrated during three flights aboard the European M55-Geophysica stratospheric research aircraft, as part of the AMMA/SCOUT-03 (African Monsoon Multidisciplinary Analysis/Stratospheric Climate links with emphasis on the Upper Troposphere and lower stratosphere) campaign in Burkina Faso in August 2006. One-second averaged, vertical profiles of delta(2)H, delta(17)O and delta(18)O in the upper troposphere are shown, as are the delta(17)O-delta(18)O and delta(2)H-delta(18)O relations. The data are discussed with reference to a Rayleigh distillation model. As expected, there is no indication of non-mass-dependent fractionation (also known as mass-independent fractionation) in the troposphere. Furthermore, improvements to the thermal management system and a move to a (cryogen-free) longer-wavelength laser source are discussed, which together should result in approximately two orders of magnitude improvement of the sensitivity.

  10. Validation of Chlorine and Oxygen Isotope Ratio Analysis to Differentiate Perchlorate Sources and to Document Perchlorate Biodegradation

    DTIC Science & Technology

    2011-12-01

    Guidance Document Validation of Chlorine and Oxygen Isotope Ratio Analysis To Differentiate Perchlorate Sources and to Document Perchlorate...Manual for Forensic Analysis of Perchlorate in Grotmdwater using W912-HQ-0 5-C-0022 Chlorine and Oxygen Isotopic Analyses 5b. GRANT NUMBER NA 5c...natural. Chlorine and oxygen isotopic analyses of perchlorate provide the primaty direct approach whereby different sources of perchlorate can be

  11. Chemistry and isotope ratios of sulfur in basalts and volcanic gases at Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Sakai, H.; Casadevall, T.J.; Moore, J.G.

    1982-01-01

    Eighteen basalts and some volcanic gases from the submarine and subaerial parts of Kilauea volcano were analyzed for the concentration and isotope ratios of sulfur. By means of a newly developed technique, sulfide and sulfate sulfur in the basalts were separately but simultaneously determined. The submarine basalt has 700 ?? 100 ppm total sulfur with ??34S??s of 0.7 ?? 0.1 ???. The sulfate/sulfide molar ratio ranges from 0.15 to 0.56 and the fractionation factor between sulfate and sulfide is +7.5 ?? 1.5???. On the other hand, the concentration and ??34S??s values of the total sulfur in the subaerial basalt are reduced to 150 ?? 50 ppm and -0.8 ?? 0.2???, respectively. The sulfate to sulfide ratio and the fractionation factor between them are also smaller, 0.01 to 0.25 and +3.0???, respectively. Chemical and isotopic evidence strongly suggests that sulfate and sulfide in the submarine basalt are in chemical and isotopic equilibria with each other at magmatic conditions. Their relative abundance and the isotope fractionation factors may be used to estimate the f{hook}o2 and temperature of these basalts at the time of their extrusion onto the sea floor. The observed change in sulfur chemistry and isotopic ratios from the submarine to subaerial basalts can be interpreted as degassing of the SO2 from basalt thereby depleting sulfate and 34S in basalt. The volcanic sulfur gases, predominantly SO2, from the 1971 and 1974 fissures in Kilauea Crater have ??34S values of 0.8 to 0.9%., slightly heavier than the total sulfur in the submarine basalts and definitely heavier than the subaerial basalts, in accord with the above model. However, the ??34S value of sulfur gases (largely SO2) from Sulfur Bank is 8.0%., implying a secondary origin of the sulfur. The ??34S values of native sulfur deposits at various sites of Kilauea and Mauna Loa volcanos, sulfate ions of four deep wells and hydrogen sulfide from a geothermal well along the east rift zone are also reported. The high

  12. Hydrogen isotope ratios of leaf wax n-alkanes in grasses are insensitive to transpiration

    NASA Astrophysics Data System (ADS)

    McInerney, Francesca A.; Helliker, Brent R.; Freeman, Katherine H.

    2011-01-01

    We analyzed hydrogen isotope ratios of high-molecular weight n-alkanes ( δD l) and oxygen isotope ratios of α-cellulose ( δ18O C) for C 3 and C 4 grasses grown in the field and in controlled-environment growth chambers. The relatively firm understanding of 18O-enrichment in leaf water and α-cellulose was used to elucidate fractionation patterns of δD l signatures. In the different relative humidity environments of the growth chambers, we observed clear and predictable effects of leaf-water enrichment on δ18O C values. Using a Craig-Gordon model, we demonstrate that leaf water in the growth chamber grasses should have experienced significant D-enriched due to transpiration. Nonetheless, we found no effect of transpirational D-enrichment on the δD l values. In field samples, we saw clear evidence of enrichment (correlating with relative humidity of the field sites) in both δ18O C and δD l. These seemingly contrasting results could be explained if leaf waxes are synthesized in an environment that is isotopically similar to water entering plant roots due to either temporal or spatial isolation from evaporatively enriched leaf waters. For grasses in the controlled environment, there was no enrichment of source water, whereas enrichment of grass source water via evaporation from soils and/or stems was likely for grass samples grown in the field. Based on these results, evaporation from soils and/or stems appears to affect δD l, but transpiration from leaves does not. Further evidence for this conclusion is found in modeling expected net evapotranspirational enrichment. A Craig-Gordon model applied to each of the field sites yields leaf water oxygen isotope ratios that can be used to accurately predict the observed δ18O C values. In contrast, the calculated leaf water hydrogen isotope ratios are more enriched than what is required to predict observed δD l values. These calculations lend support to the conclusion that while δ18O C reflects both soil

  13. Method for ultra-trace cesium isotope ratio measurements from environmental samples using thermal ionization mass spectrometry

    SciTech Connect

    Snow, Mathew S.; Snyder, Darin C.; Mann, Nick R.; White, Byron M.

    2015-05-01

    135Cs/137Cs isotope ratios can provide the age, origin and history of environmental Cs contamination. Relatively high precision 135Cs/137Cs isotope ratio measurements from samples containing femtogram quantities of 137Cs are needed to accurately track contamination resuspension and redistribution following environmental 137Cs releases; however, mass spectrometric analyses of environmental samples are limited by the large quantities of ionization inhibitors and isobaric interferences which are present at relatively high concentrations in the environment. We report a new approach for Cs purification from environmental samples. An initial ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) column provides a robust method for extracting Cs under a wide variety of sample matrices and mass loads. Cation exchange separations using a second AMP-PAN column result in more than two orders of magnitude greater Cs/Rb separation factors than commercially available strong cation exchangers. Coupling an AMP-PAN cation exchanging step to a microcation column (AG50W resin) enables consistent 2-4% (2σ) measurement errors for samples containing 3-6,000 fg 137Cs, representing the highest precision 135Cs/137Cs ratio measurements currently reported for soil samples at the femtogram level.

  14. Stable-isotope ratios of hydrogen and oxygen in precipitation at Norman, Oklahoma, 1996-2008

    USGS Publications Warehouse

    Jaeschke, Jeanne B.; Scholl, Martha A.; Cozzarelli, Isabelle M.; Masoner, Jason R.; Christenson, Scott; Qi, Haiping

    2011-01-01

    Precipitation samples for measurement of stable-isotope ratios of hydrogen (delta2H) and oxygen (delta18O) were collected at the Norman Landfill Research Site in Norman, Oklahoma, from May 1996 to October 2008. Rainfall amounts also were measured at the site (U.S. Geological Survey gaging station 07229053) during the collection period. The delta2H of precipitation samples ranged from -121.9 to +8.3 per mil, and the delta18O of precipitation ranged from -16.96 to +0.50 per mil. The volume-weighted average values for delta2H and delta18O of precipitation over the 12-year measurement period were -31.13 per mil for delta2H and -5.57 per mil for delta18O. Average summer-season delta2H and delta18O values of precipitation usually were more positive (enriched in the heavier isotopes) than winter values.

  15. Sedimentary nitrogen isotopic ratio as a recorder for surface ocean nitrate utilization

    SciTech Connect

    Altabet, M.A.; Francois, R. )

    1994-03-01

    The availability of nutrients in the near surface ocean is an important control on primary production, whose variability over geologic time may have altered major biogeochemical cycles. Ocean models have suggested a specific link between glacial/interglacial variations in atmospheric CO2 concentrations and changes in nutrient concentration at the surface of high latitude seas. Isotope ratios have been used to evaluate nutrients in the ocean surface. To test the fidelity with which surface generated isotopic signals are recorded in deep-sea sediments, this study focused on equatorial Pacific ocean and the southern ocean. In both regions large gradients in near surface NO3 concentration and depletion dominate any local temporal variation. Corresponding gradients were found in Nitrogen 15 and compared to sedimentary values. Results indicate that strong near surface N15 gradients are indeed recorded in underlying surface sediments. 55 refs., 10 figs., 1 tab.

  16. The stable carbon isotope ratios in benthic food webs of the gulf of Calvi, Corsica

    NASA Astrophysics Data System (ADS)

    Dauby, Patrick

    1989-02-01

    The Gulf of Calvi, Corsica, presents a wide diversity of biocoenoses, amongst which the seagrass Posidonia meadow is prevalent. More than 100 plant, animal and sediment samples from various biotopes were analysed for their stable carbon isotope ratios, to assess carbon flows within the food chains. Marine plants display a wide range of δ 13C values, from -6 to -32‰ but with three relatively well distinct peaks for Posidonia, brown algae and phytoplankton (-9, -19 and -23‰, respectively), which are the main carbon sources. The range of isotopic values of animals is narrower, from -14 to -24‰, suggesting that they feed mainly on algae and plankton. Computations based on simple equations show the proportion of each carbon source in the diet of the animals. Posidonia, notwithstanding their important biomass, appear to be a minor food source; this is possibly because of the transfer of their dead leaves, towards the shorelines, in winter.

  17. New developments in high-resolution gas source isotope ratio mass spectrometers

    NASA Astrophysics Data System (ADS)

    Clog, M. D.; Ellam, R. M.; Hilkert, A.; Schwieters, J. B.; Hamilton, D.

    2015-12-01

    Gas source isotope ratio mass spectrometry (IRMS) is one of the main tools for the study of the isotopic compositions of light elements, extended in the last 10 years to the measurements of molecules bearing several rare isotopes (e.g., clumped isotopes of CO2) as well as position-specific isotopic substitutions in a few choice analytes (e.g., in N2O). Measuring those low-abundance species creates several technical challenges, with the main one being the presence of numerous isobaric interferences. Those can come either from contaminants (background gases present in the source of the instrument or impurities introduced with the analyte), or unwanted beams created by the analyte itself during the ionization process (for example adducts and fragments). In order to avoid those isobaric species, new high-resolution, double-focusing IRMS have been developed. We present here the capabilities of the production series version of the ThermoFisher Scientific 253 Ultra, which was installed at SUERC in July 2015. The instrument is capable of reaching high mass resolving power (above 40,000) and is similar in design to the Caltech 253 Ultra prototype. The collector array has 9 detector positions, 8 of which are movable. Faraday cups at each detector can be linked to amplifiers with gains ranging from 3.108 to 1012 Ohm (and 1013 Ohm amplifiers being currently developped). There are also 4 ion counters, one of which located behind a retardation lens (RPQ) to limit background noise and improve abundance sensitivity. Additionally, one of the Faraday cup in the new instrument has a very narrow entrance slit, allowing high mass resolving power and high resolution, with a complete separation of the ion beams instead of complex peak shapes corresponding to overlapping ion beams. This will potentially remove the need for adduct lines or peak stripping schemes for analytes like CH4.

  18. Microbial activities and phosphorus cycling: An application of oxygen isotope ratios in phosphate

    NASA Astrophysics Data System (ADS)

    Stout, Lisa M.; Joshi, Sunendra R.; Kana, Todd M.; Jaisi, Deb P.

    2014-08-01

    Microorganisms carry out biochemical transformations of nutrients that make up their cells. Therefore, understanding how these nutrients are transformed or cycled in natural environments requires knowledge of microbial activity. Commonly used indicators for microbial activity typically include determining microbial respiration by O2/CO2 measurements, cell counts, and measurement of enzyme activities. However, coupled studies on nutrient cycling and microbial activity are not given enough emphasis. Here we apply phosphate oxygen isotope ratios (δ18OP) as a tool for measurement of microbial activity and compare the rate of isotope exchange with methods of measuring microbial activities that are more commonly applied in environmental studies including respiration, dehydrogenase activity, alkaline phosphatase activity, and cell counts. Our results show that different bacteria may have different strategies for P uptake, storage and release, their respiration and consequently expression of DHA and APase activities, but in general the trend of their enzyme activities are comparable. Phosphate δ18OP values correlated well with these other parameters used to measure microbial activity with the strongest linear relationships between δ18OP and CO2 evolution (r = -0.99). Even though the rate of isotope exchange for each microorganism used in this study is different, the rate per unit CO2 respiration showed one general trend, where δ18OP values move towards equilibrium while CO2 is generated. While this suggests that P cycling among microorganisms used in this study can be generalized, further research is needed to determine whether the microorganism-specific isotope exchange trend may occur in natural environments. In summary, phosphate oxygen isotope measurements may offer an alternative for use as a tracer to measure microbial activity in soils, sediments, and many other natural environments.

  19. Oxygen and carbon isotope ratios of hydrothermal minerals from Yellowstone drill cores

    USGS Publications Warehouse

    Sturchio, N.C.; Keith, T.E.C.; Muehlenbachs, K.

    1990-01-01

    Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface (in situ temperatures ranging from 81 to 199??C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The ??18O values of the thirty-two analyzed silica samples (quartz, chalcedony, ??-cristobalite, and ??-cristobalite) range from -7.5 to +2.8???. About one third of the silica 7samples have ??18O values that are consistent with isotopic equilibrium with present thermal waters; most of the other silica samples appear to have precipitated from water enriched in 18O (up to 4.7???) relative to present thermal water, assuming precipitation at present in situ temperatures. Available data on fluid-inclusion homogenization temperatures in hydrothermal quartz indicate that silica precipitation occurred mostly at temperatures above those measured during drilling and imply that 15O enrichments in water during silica precipitation were generally larger than those estimated from present conditions. Similarly, clay minerals (celadonite and smectite) have ??18O values higher (by 3.5 to 7.9???) than equilibrium values under present conditions. In contrast, all eight analyzed calcite samples are close to isotopic equilibrium with present thermal waters. The frequent incidence of apparent 18O enrichment in thermal water from which the hydrothermal minerals precipitated may indicate that a higher proportion of strongly 18O-enriched deep hydrothermal fluid once circulated through shallow portions of the Yellowstone system, or that a recurring transient 18O-enrichment effect occurs at shallow depths and is caused either by sudden decompressional boiling or by isotopic exchange at low water/rock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are consistent with deposition

  20. Silicon isotope ratios affected by sodium-induced broadband interference in high resolution multicollector-ICPMS.

    PubMed

    Pramann, Axel; Rienitz, Olaf; Schiel, Detlef

    2012-12-04

    The measurement of isotope ratios of silicon highly enriched in (28)Si ("Si28", x((28)Si) > 99.99%) is influenced by a significant interference (20%) on the (30)Si(+) signal when using a cup configuration of C ((29)Si(+)) and H3 ((30)Si(+)) on a Neptune MC-ICPMS. This interference was observed in silicon solutions with aqueous NaOH (w(NaOH) > 0.001 g/g) and in highly concentrated aqueous NaOH blank solutions (e.g., w(NaOH) = 0.25 g/g) but never in KOH solutions. By redirecting the ions, the interference was detected with all other Faraday cups except the center cup. The interference can be explained by ion scattering induced by the presence of large amounts of sodium. Due to its shielded location, these stray ions were not detected in the center cup. This effect explains an anomalous increase of the abundance of the (30)Si(+) signal in (30)Si/(29)Si isotope ratio measurements made using aqueous NaOH blank solutions with w(NaOH) ≥ 0.001 g/g. For silicon isotopic measurements, it is recommended to use alkaline solutions for sample dissolution and dilution that do not contain sodium. The effects of this interference are extremely important for the experimental determination of the Avogadro constant N(A) using the "silicon sphere approach". It can also have a significant effect on Si isotope analyses in matrices with a naturally high concentration of sodium (e.g., seawater).

  1. Ptolemy an Instrument to Measure Stable Isotopic Ratios of Key Volatiles on a Cometary Nucleus

    NASA Astrophysics Data System (ADS)

    Wright, I. P.; Barber, S. J.; Morgan, G. H.; Morse, A. D.; Sheridan, S.; Andrews, D. J.; Maynard, J.; Yau, D.; Evans, S. T.; Leese, M. R.; Zarnecki, J. C.; Kent, B. J.; Waltham, N. R.; Whalley, M. S.; Heys, S.; Drummond, D. L.; Edeson, R. L.; Sawyer, E. C.; Turner, R. F.; Pillinger, C. T.

    2007-02-01

    A fundamental goal of cometary studies is to determine the exact relationship between these bodies and the Solar System the question(s) can be summarised as follows: did comets originate during the same events that spawned the Sun and planets, are they more primitive bodies that record a pre-solar history, or are they interstellar materials collected in relatively more recent times? Now, whatever the origin of comets, it is entirely possible that they could, in part, contain interstellar or pre-solar components indeed, it seems rather likely in light of the fact that primitive meteorites contain such entities. These particular components are likely to be refractory (dust, macromolecular organic complexes, etc.). Of more relevance to the issues above are the volatile constituents, which make up the bulk of a comet's mass. Since these materials, by their very nature, volatilise during perihelion passage of a comet they can, in some instances, be detected and measured spectroscopically. Perhaps the most useful species for isotopic investigations are C2, HCN and CN. Unfortunately, spectroscopic measurements can only currently be made with accuracies of ±10 to ±20%. As such it is very often not practical to conclude anything further than the fact that isotopic measurements are compatible with ‘`solar’' values, which tends to imply an origin from the margins of the solar accretion disk. But there is another problem with the spectroscopic measurements since these are made on gaseous species in the coma (and relatively minor species at that) it is impossible to be certain that these represent the true nuclear values. In other words, if the processes of sublimation, active jetting, and photochemistry in the coma impart isotopic fractionation, the spectroscopic measurements could give a false impression of the true isotope ratios. What is required is an experiment capable of measuring isotopic ratios at the very surface of a comet. Herein we describe the Ptolemy

  2. Lead isotope ratio measurements as indicators for the source of lead poisoning in Mute swans (Cygnus olor) wintering in Puck Bay (northern Poland).

    PubMed

    Binkowski, Łukasz J; Meissner, Włodzimierz; Trzeciak, Marta; Izevbekhai, Kelvin; Barker, James

    2016-12-01

    Lead (Pb) poisoning is most commonly linked amongst anthropogenically-caused deaths in waterfowl and this is often associated with hunting and fishing activities. However, the exact identification of the source may be difficult with commonly-used techniques. We have studied isotope ratios using Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) to investigate the source of Pb in the blood of Mute swans (n = 49) wintering in northern Poland. We compared the values of isotopic ratios from blood and ammunition pellets available on the Polish market. The mean Pb concentrations found was 0.241 μg/g (w/w) and nearly half of the blood specimens had elevated Pb levels (higher than the cited 0.23 μg/g w/w threshold of poisoning). Only the mean 208/206 Pb isotope ratio was similar in blood and pellet samples. Mean ratios of isotopes 206/204, 206/207 and 208/207 in swans' blood and in pellets differed significantly. Moreover, coefficients of variation were higher in blood samples than in pellets. These discrepancies and significant differences in abundance of (204)Pb and (207)Pb isotopes in both materials indicated that pellets available today on the Polish market were not the source of Pb in the blood of Mute swans wintering in northern Poland.

  3. Assimilation of benzene carbon through multiple trophic levels traced by different stable isotope probing methodologies.

    PubMed

    Bastida, Felipe; Jechalke, Sven; Bombach, Petra; Franchini, Alessandro G; Seifert, Jana; von Bergen, Martin; Vogt, Carsten; Richnow, Hans H

    2011-08-01

    The flow of benzene carbon along a food chain consisting of bacteria and eukaryotes, including larvae (Diptera: Chironomidae), was evaluated by total lipid fatty acids (TLFAs)-, amino acid- and protein-stable isotope probing (SIP). A coconut-fibre textile, colonized by a benzene-degrading biofilm, was sampled in a system established for the remediation of benzene, toluene, ethylbenzene and xylenes (BTEX)-polluted groundwater and incubated with (12)C- and [(13)C(6)]-benzene (>99 at.%) in a batch-scale experiment for 2-8 days. After 8 days, Chironomus sp. larvae were added to study carbon flow to higher trophic levels. Gas chromatography-combustion-isotope ratio monitoring mass spectrometry of TLFA showed increased isotope ratios in the (13)C-benzene-incubated biofilm. A higher (13)C-enrichment was observed in TLFAs, indicative of Gram-negative bacteria than for Gram-positive. Fatty acid indicators of eukaryotes showed significant (13)C-incorporation, but to a lower extent than bacterial indicators. Fatty acids extracted from larvae feeding on (13)C-biofilm reached an isotopic ratio of 1.55 at.%, illustrating that the larvae feed, to some extent, on labelled biomass. No (13)C-incorporation was detectable in larval proteins after their separation by sodium-dodecyl sulphate-polyacrylamide gel electrophoresis and analysis by nano-liquid-chromatography-mass spectrometry. The flow of benzene-derived carbon could be traced in a food web consisting of bacteria and eukaryotes.

  4. Does transpiration matter to the hydrogen isotope ratios of leaf wax n-alkanes? (Invited)

    NASA Astrophysics Data System (ADS)

    McInerney, F. A.; Helliker, B. R.; Freeman, K. H.

    2010-12-01

    Transpiration and evaporation from soils both affect he hydrogen isotope composition of leaf water, but the extent to which they effect the hydrogen isotope ratio of leaf wax lipids is still under debate. To address this question, we analyzed hydrogen isotope ratios of high-molecular weight n-alkanes (δDl) and oxygen isotope ratios of α-cellulose (δ18OC) for C3 and C4 grasses grown in the field and in controlled-environment growth chambers. The relatively firm understanding of 18O-enrichment in leaf water and α-cellulose was used to elucidate fractionation patterns of δDl signatures. In the different relative humidity environments of the growth chambers, we observed clear and predictable effects of leaf-water enrichment on δ18OC values. Using a Craig-Gordon model, we demonstrate that leaf water in the growth chamber grasses should have experienced significant D-enriched due to transpiration. Nonetheless, we found no effect of transpirational D-enrichment on the δDl values. In field samples, we saw clear evidence of enrichment (correlating with relative humidity of the field sites) in both δ18OC and δDl. These seemingly contrasting results can be explained if leaf waxes are synthesized in an environment that is isotopically similar to water entering plant roots due to either temporal or spatial isolation from evaporatively enriched leaf waters. For grasses in the controlled environment, there was no enrichment of source water, whereas enrichment of grass source water via evaporation from soils and/or stems was likely for grass samples grown in the field. Based on these results, evaporation from soils and/or stems appears to affect δDl, but transpiration from leaves does not. Further evidence for this conclusion is found in modeling expected net evapotranspirational enrichment. A Craig-Gordon model applied to each of the field sites yields leaf water oxygen isotope ratios that can be used to accurately predict the observed δ18OC values. In contrast, the

  5. Stable carbon isotope ratios of intact GDGTs indicate heterogeneous sources to marine sediments

    NASA Astrophysics Data System (ADS)

    Pearson, Ann; Hurley, Sarah J.; Walter, Sunita R. Shah; Kusch, Stephanie; Lichtin, Samantha; Zhang, Yi Ge

    2016-05-01

    Thaumarchaeota, the major sources of marine glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), are believed to fix the majority of their carbon directly from dissolved inorganic carbon (DIC). The δ13C values of GDGTs (δ13CGDGT) may be powerful tools for reconstructing variations in the ocean carbon cycle, including paleoproductivity and water mass circulation, if they can be related to values of δ13CDIC. To date, isotope measurements primarily are made on the C40 biphytane skeletons of GDGTs, rather than on complete tetraether structures. This approach erases information revealed by the isotopic heterogeneity of GDGTs within a sample and may impart an isotopic fractionation associated with the ether cleavage. To circumvent these issues, we present δ13C values for GDGTs from twelve recent sediments representing ten continental margin locations. Samples are purified by orthogonal dimensions of HPLC, followed by measurement of δ13C values by Spooling Wire Microcombustion (SWiM)-isotope ratio mass spectrometry (IRMS) with 1σ precision and accuracy of ±0.25‰. Using this approach, we confirm that GDGTs, generally around -19‰, are isotopically "heavy" compared to other marine lipids. However, measured δ13CGDGT values are inconsistent with predicted values based on the 13C content of DIC in the overlying water column and the previously-published biosynthetic isotope fractionation for a pure culture of an autotrophic marine thaumarchaeon. In some sediments, the isotopic composition of individual GDGTs differs, indicating multiple source inputs. The data appear to confirm that crenarchaeol primarily is a biomarker for Thaumarchaeota, but its δ13C values still cannot be explained solely by autotrophic carbon fixation. Overall the complexity of the results suggests that both organic carbon assimilation (ca. 25% of total carbon) and multiple source(s) of exogenous GDGTs (contributing generally <30% of input to sediments) are necessary to explain the observed

  6. Acidification processes and soil leaching influenced by agricultural practices revealed by strontium isotopic ratios

    NASA Astrophysics Data System (ADS)

    Pierson-Wickmann, Anne-Catherine; Aquilina, Luc; Weyer, Christina; Molénat, Jérôme; Lischeid, Gunnar

    2009-08-01

    In natural river systems, the chemical and isotopic composition of stream- and ground waters are mainly controlled by the geology and water-rock interactions. The leaching of major cations from soils has been recognized as a possible consequence of acidic deposition from atmosphere for over 30 years. Moreover, in agricultural areas, the application of physiological acid fertilizers and nitrogen fertilizers in the ammonia form may enhance the cation leaching through the soil profile into ground- and surface waters. This origin of leached cations has been studied on two small and adjacent agricultural catchments in Brittany, western France. The study catchments are drained by two first-order streams, and mainly covered with cambisoils, issued from the alteration and weathering of a granodiorite basement. Precipitations, soil water- and NH 4 acetate-leachates, separated minerals, and stream waters have been investigated. Chemical element ratios, such as Ba/Sr, Na/Sr and Ca/Sr ratios, as well as Sr isotopic ratios are used to constrain the relative contribution from potential sources of stream water elements. Based on Sr isotopic ratio and element concentration, soil water- and NH 4 acetate leaching indicates (1) a dominant manure/slurry contribution in the top soil, representing a cation concentrated pool, with low 87Sr/ 86Sr ratios; (2) in subsoils, mineral dissolution is enhanced by fertilizer application, becoming the unique source of cations in the saprolite. The relatively high weathering rates encountered implies significant sources of cations which are not accessory minerals, but rather plagioclase and biotite dissolution. Stream water has a very different isotopic and chemical composition compared to soil water leaching suggesting that stream water chemistry is dominated by elements issued from mineral and rock weathering. Agriculture, by applications of chemical and organic fertilizers, can influence the export of major base cations, such as Na +. Plagioclase

  7. Metrology for laser spectroscopic concentration and isotope ratio measurements of atmospheric greenhouse gases

    NASA Astrophysics Data System (ADS)

    Nwaboh, Javis; Manninen, Albert; Mohn, Joachim; Petersen, Jan C.; Werhahn, Olav; Ebert, Volker

    2015-04-01

    Continuous, accurate and precise measurements of greenhouse gases (GHG) and their isotopic composition are required to understand the global cycle as well as source and sink processes of these environmentally harmful substances. Part of the EMRP project HIGHGAS (Metrology for high-impact greenhouse gases) [1] focuses on spectroscopic methods for GHG isotopic composition measurements and optical transfer standards. Harmonization of terminologies and concepts used in the GHG measurement communities and the metrology community are in focus, especially for isotope ratio measurements by laser spectroscopy, where gas metrology is still at an early stage. The focus of the HIGHGAS project here is on 13C/12C and 18O/16O ratios in CO2, 15N/14N ratios in N2O and 13C/12C and 2H/1H ratios in CH4. As an alternative and complement of gas mixture standards, optical spectroscopic transfer standards for CO2 and CO shall be developed providing concentration results that are directly traceable to the international system of units (SI). Optical transfer standards offer an alternative in situ calibration route for other GHG measurement devices operating in the field. An optical transfer standard becomes particularly interesting when measuring sticky or reactive gases where cylinder-based reference gas mixtures may not be feasible. We present an approach to perform IR-spectrometry on gases with results directly traceable to the SI. This is crucial for the development of optical spectroscopic transfer standards providing SI-traceability to field measurements. Ideas for spectroscopic isotope ratio measurements aiming at SI-traceability will be discussed. Finally, we demonstrate the current performance and limitations of our measurement approaches and project possible solutions. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS (Metrology for high-impact greenhouse gases). The EMRP is jointly funded by the

  8. Use of stable carbon and nitrogen isotope ratios in size segregated aerosol particles for the O/I penetration evaluation

    NASA Astrophysics Data System (ADS)

    Garbaras, Andrius; Garbariene, Inga; Masalaite, Agne; Ceburnis, Darius; Krugly, Edvinas; Kvietkus, Kestutis; Remeikis, Vidmantas; Martuzevicius, Dainius

    2015-04-01

    Stable carbon and nitrogen isotope ratio are successfully used in the atmospheric aerosol particle source identification [1, 2], transformation, pollution [3] research. The main purpose of this study was to evaluate the penetration of atmospheric aerosol particles from outdoor to indoor using stable carbon and nitrogen isotope ratios. Six houses in Kaunas (Lithuania) were investigated during February and March 2013. Electrical low pressure impactor was used to measure in real time concentration and size distribution of outdoor aerosol particles. ELPI+ includes 15 channels covering the size range from 0.017 to 10.0 µm. The 25 mm diameter aluminium foils were used to collect aerosol particles. Gravimetric analysis of samples was made using microbalance. In parallel, indoor aerosol samples were collected with a micro-orifice uniform deposition impactor (MOUDI model 110), where the aerosol particles were separated with the nominal D50 cut-off sizes of 0.056, 0.1, 0.18,0.32,0.56, 1.0, 1.8, 3.2, 5.6, 10, 18 μm for impactor stages 1-11, respectively. The impactor was run at a flow rate of 30 L/min. Air quality meters were used to record meteorological conditions (temperature, relative humidity) during the investigated period. All aerosol samples were analyzed for total carbon (TC) and total nitrogen (TN) contents and their isotopic compositions using elemental analyzer (EA) connected to the stable isotope ratio mass spectrometer (IRMS). TC concentration in indoors ranged from 1.5 to 247.5 µg/m3. During the sampling period outdoors TN levels ranged from 0.1 to 10.9 µg/m3. The obtained outdoor δ13C(PM2.5) values varied from -24.21 to -26.3‰, while the δ15N values varied from 2.4 to 11.1 ‰ (average 7.2±2.5 ‰). Indoors carbonaceous aerosol particles were depleted in 13C compared to outdoors in all sampling sites. This depletion in δ13C varied from 0.1 to 3.2 ‰. We think that this depletion occurs due ongoing chemical reactions (oxidation) when aerosol

  9. Sr-Nd-Hf-Pb Isotope Ratios in Recent NE Lau Lavas

    NASA Astrophysics Data System (ADS)

    Todd, E.; Gill, J. B.; Freymuth, H.

    2009-12-01

    Sr-Nd-Hf-Pb isotope ratios in recently erupted NE Lau lavas are being measured and results will be presented. The recent W. Mata boninites lie slightly west of the northern termination of the Tongan volcanic front in an area where previously dredged boninites are enriched in LREE and HFSE. They are interpreted as containing an OIB-type mantle source component fluxed by slab-derived fluids (Falloon et al., 2007; Pearce et al., 2007). However, their Sr-Nd-Pb isotope ratios do not match any known component from the Samoan plume, pelagic sediment, or Louisville Ridge-derived volcaniclastic sediment. Their most distinctive isotopic characteristics are low 87Sr/86Sr and high 206Pb/204Pb relative to Nd-Hf isotope ratios. They are displaced toward HIMU-type basalts from the Cook-Austral islands (e.g., Tubuai) and have been interpreted as derived from diverse HIMU, EMI, and EMII mantle source components that are carried southward from beneath the Pacific Plate into the NE Lau Basin. Basalts from the NE Lau Spreading Center have more of a Indian-MORB source than do the boninites, and are similar to the <3 Ma OIB-type basalts from Fiji (Gill, 1984 and unpub.). If so, then some diverse enriched “plums” melt out of southward-advecting MORB-source “pudding” over as little as 100 km, whereas others persist for ~500 km to Fiji. Data for the recently erupted samples will test these interpretations, and will be compared to characteristics of the earliest (7.4 Ma) boninitic lavas in the region that have less of the OIB component. References: T. J. Falloon, L. Danyushevsky, A. J. Crawford, R. Maas, J. D. Woodhead, S. Eggins, S. Bloomer, D. J. Wright, S. K. Zlobin, and A. R. Stacey. Multiple mantle plume components involved in the petrogenesis of subduction-related lavas from the northern termination of the Tonga Arc and northern Lau Basin: Evidence from the geochemistry of arc and backarc submarine volcanics. Geochemistry, Geophysics, Geosystems, 8(Q09003):45, 2007. J. B. Gill

  10. PHOTOCHEMICALLY-INDUCED ALTERATION OF STABLE CARBON ISOTOPE RATIOS (DELTA C-13) IN TERRIGENOUS DISSOLVED ORGANIC CARBON

    EPA Science Inventory

    Exposure of riverine waters to natural sunlight initiated alterations in stable carbon isotope ratios (delta C-13) of the associated dissolved organic carbon (DOC). Water samples were collected from two compositionally distinct coastal river systems in the southeastern United Sta...

  11. Independent Verification of Research Reactor Operation (Analysis of the Georgian IRT-M Reactor by the Isotope Ratio Method)

    SciTech Connect

    Cliff, John B.; Frank, Douglas P.; Gerlach, David C.; Gesh, Christopher J.; Little, Winston W.; Reid, Bruce D.; Tsiklauri, Georgi V.; Abramidze, Sh; Rostomashvili, Z.; Kiknadze, G.; Dzhavakhishvily, O.; Nabakhtiani, G.

    2010-08-11

    The U.S. Department of Energy’s Office of Nonproliferation and International Security (NA-24) develops technologies to aid in implementing international nuclear safeguards. The Isotope Ratio Method (IRM) was successfully developed in 2005 – 2007 by Pacific Northwest National Laboratory (PNNL) and the Republic of Georgia’s Andronikashvili Institute of Physics as a generic technology to verify the declared operation of water-moderated research reactors, independent of spent fuel inventory. IRM estimates the energy produced over the operating lifetime of a fission reactor by measuring the ratios of the isotopes of trace impurity elements in non-fuel reactor components.The Isotope Ratio Method is a technique for estimating the energy produced over the operating lifetime of a fission reactor by measuring the ratios of the isotopes of impurity elements in non-fuel reactor components.

  12. Determining Sources and Transport of Nuclear Contamination in Hudson River Sediments with Plutonium, Neptunium, and Cesium isotope ratios

    NASA Astrophysics Data System (ADS)

    Kenna, T. C.; Chillrud, S. N.; Chaky, D. A.; Simpson, H. J.; McHugh, C. M.; Shuster, E. L.; Bopp, R. F.

    2004-12-01

    Different sources of radioactive contamination contain characteristic and identifiable isotopic signatures, which can be used to study sediment transport. We focus on Pu-239, Pu-240, Np-237 and Cs-137, which are strongly bound to fine grained sediments. The Hudson River drainage basin has received contamination from at least three separate sources: 1) global fallout from atmospheric testing of nuclear weapons, which contributed Pu, Np and Cs; 2) contamination resulting from reactor releases at the Indian Point Nuclear Power Plant (IPNPP) located on the Hudson River Estuary ˜70km north of New York Harbor, where records document releases of Cs-137; 3) contamination resulting from activities at the Knolls Atomic Power Laboratory (KAPL) located on the Mohawk River, where incomplete records document releases of Cs-137 but no mention is made of Pu or Np. Here we report measurements of Pu isotopes, Np-237 and Cs-137 for a series of sediment cores collected from various locations within the drainage basin: 1) Mohawk River downstream of KAPL, 2) Hudson River upstream of its confluence with the Mohawk River, and 3) lower Hudson River at a location in close proximity to IPNPP. In addition, we present data from selected samples from two other lower Hudson River locations: One site located ˜30km downstream of IPNPP and another ˜30km upstream of IPNPP. By comparing the isotopic ratios Pu-240/Pu-239, Np-237/Pu-239, and Cs-137/Pu-239, measured in fluvial sediments to mean global fallout values, it is possible to identify and resolve different sources of non-fallout contamination. To date, isotopic data for sediments indicate non-fallout sources of Pu-239, Pu-240, and Cs-137; Np-237, however, appears to originate from global fallout only. Mohawk River sediments downstream of KAPL exhibit enrichments in Pu-239, Pu-240, and Cs-137 that are 7 to 20 times higher than levels expected from global fallout as indicated from Np-237. The elevated levels, non-fallout isotopic signatures

  13. Measurement of Uranium Isotope Ratios in Keratinous Materials: A Noninvasive Bioassay for Special Nuclear Material.

    PubMed

    Brockman, John D; Brown, John W N; Morrell, Jonathan S; Robertson, J David

    2016-09-06

    Hair, toenail, and fingernail are noninvasive, integrative biological monitors routinely used to assess mineral intake.1-4 In this study, we demonstrate the feasibility of distinguishing between exposure to natural, depleted, and enriched U by measuring the (235)U/(238)U, (234)U/(238)U, and (236)U/(238)U ratios in the hair, fingernails, and toenails of occupationally exposed workers and control volunteers. The exposure history of cases and controls to non-natural U was assessed through voluntary self-reporting using a simple questionnaire. The measured U isotope ratios and U concentration in the hair, toenail, and fingernail of cases were compared to a nonexposed control group. No difference was observed in the uranium concentration between the two groups. Significant differences between the cases and the control group were observed in the (235)U/(238)U and (236)U/(238)U isotope ratios but not the (234)U/(238)U. This is the first time that hair, fingernail, and toenail have been demonstrated to be sensitive to occupational exposure to enriched and depleted U, a result with significant implications for proliferation compliance monitoring.

  14. Isomer residual ratio of odd-odd isotope {sup 180}Ta in supernova nucleosynthsis

    SciTech Connect

    Hayakawa, Takehito; Kajino, Toshitaka; Chiba, Satoshi; Mathews, Grant

    2010-06-01

    The nucleosynthesis of {sup 180}Ta has remained an unsolved problem and as its origin many nucleosynthesis mechanisms have been proposed. This isotope has the unique feature that the naturally occurring abundance of {sup 180}Ta is actually a meta-stable isomer (half-life of >=10{sup 15} yr), while the ground state is a 1{sup +} unstable state which beta-decays with a half-life of only 8.15 hr. We have made a new time-dependent calculation of {sup 180}Ta meta-stable isomer residual ratio after supernova neutrino-induced reactions. This residual isomer ratio is crucial for understanding the production and survival of this naturally occurring rare isotope. We have constructed a new model under temperature evolution after type II supernova explosion. We include the explicit linking between the isomer and all known excited states and found that the residual ratio is insensitive to astrophysical parameters such as neutrino energy spectrum, explosion energy, decay time constant. We find that the explicit time evolution of the synthesis of {sup 180}Ta avoids the overproduction relative to {sup 138}La for a neutrino process neutrino temperature of 4 MeV.

  15. Isotopic Ratios of Carbon and Oxygen in Titan's CO Using Alma

    NASA Technical Reports Server (NTRS)

    Serigano, Joseph; Nixon, C. A.; Cordiner, M. A.; Irwin, P. G. J.; Teanby, N. A.; Charnley, S. B.; Lindberg, J. E.

    2016-01-01

    We report interferometric observations of carbon monoxide (CO) and its isotopologues in Titan's atmosphere using the Atacama Large Millimeter/submillimeter Array (ALMA). The following transitions were detected: CO (J = 1-0, 2-1, 3-2, 6-5), C-13 O (J = 2-1, 3-2, 6-5), C-18 O (J = 2-1, 3-2), and C-17 O (J = 3-2). Molecular abundances and the vertical atmospheric temperature profile were derived by modeling the observed emission line profiles using NEMESIS, a line-by-line radiative transfer code. We present the first spectroscopic detection of O-17 in the outer solar system with C-17 O detected at greater than 8 sigma confidence. The abundance of CO was determined to be 49.6 +/- 1.8 ppm, assumed to be constant with altitude, with isotopic ratios C-12/C-13 = 89.9 +/- 3.4, O-16/O-18 = 486 +/- 22, and O-16/O-17 = 2917 +/- 359. The measurements of C-12/C-13 and O-16/O-18 ratios are the most precise values obtained in Titan's atmospheric CO to date. Our results are in good agreement with previous studies and suggest no significant deviations from standard terrestrial isotopic ratios.

  16. Rapid Method for the Determination of the Stable Oxygen Isotope Ratio of Water in Alcoholic Beverages.

    PubMed

    Wang, Daobing; Zhong, Qiding; Li, Guohui; Huang, Zhanbin

    2015-10-28

    This paper demonstrates the first successful application of an online pyrolysis technique for the direct determination of oxygen isotope ratios (δ(18)O) of water in alcoholic beverages. Similar water concentrations in each sample were achieved by adjustment with absolute ethyl alcohol, and then a fixed GC split ratio can be used. All of the organic ingredients were successfully separated from the analyte on a CP-PoraBond Q column and subsequently vented out, whereas water molecules were transferred into the reaction furnace and converted to CO. With the system presented, 15-30 μL of raw sample was diluted and can be analyzed repeatedly; the analytical precision was better than 0.4‰ (n = 5) in all cases, and more than 50 injections can be made per day. No apparent memory effect was observed even if water samples were injected using the same syringe; a strong correlation (R(2) = 0.9998) was found between the water δ(18)O of measured sample and that of working standards. There was no significant difference (p > 0.05) between the mean δ(18)O value and that obtained by the traditional method (CO2-water equilibration/isotope ratio mass spectrometry) and the newly developed method in this study. The advantages of this new method are its rapidity and straightforwardness, and less test portion is required.

  17. Direct isotope ratio analysis of individual uranium-plutonium mixed particles with various U/Pu ratios by thermal ionization mass spectrometry.

    PubMed

    Suzuki, Daisuke; Esaka, Fumitaka; Miyamoto, Yutaka; Magara, Masaaki

    2015-02-01

    Uranium and plutonium isotope ratios in individual uranium-plutonium (U-Pu) mixed particles with various U/Pu atomic ratios were analyzed without prior chemical separation by thermal ionization mass spectrometry (TIMS). Prior to measurement, micron-sized particles with U/Pu ratios of 1, 5, 10, 18, and 70 were produced from uranium and plutonium certified reference materials. In the TIMS analysis, the peaks of americium, plutonium, and uranium ion signals were successfully separated by continuously increasing the evaporation filament current. Consequently, the uranium and plutonium isotope ratios, except the (238)Pu/(239)Pu ratio, were successfully determined for the particles at all U/Pu ratios. This indicates that TIMS direct analysis allows for the measurement of individual U-Pu mixed particles without prior chemical separation.

  18. Mapping and defining sources of variability in bioavailable strontium isotope ratios in the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Hartman, Gideon; Richards, Mike

    2014-02-01

    The relative contributions of bedrock and atmospheric sources to bioavailable strontium (Sr) pools in local soils was studied in Northern Israel and the Golan regions through intensive systematic sampling of modern plants and invertebrates, to produce a map of modern bioavailable strontium isotope ratios (87Sr/86Sr) for regional reconstructions of human and animal mobility patterns. The study investigates sources of variability in bioavailable 87Sr/86Sr ratios, in particular the intra-and inter-site range of variation in plant 87Sr/86Sr ratios, the range of 87Sr/86Sr ratios of plants growing on marine sedimentary versus volcanic geologies, the differences between ligneous and non-ligneous plants with varying growth and water utilization strategies, and the relative contribution of atmospheric Sr sources from different soil and vegetation types and climatic zones. Results indicate predictable variation in 87Sr/86Sr ratios. Inter- and intra-site differences in bioavailable 87Sr/86Sr ratios average of 0.00025, while the range of 87Sr/86Sr ratios measured regionally in plants and invertebrates is 0.7090 in Pleistocene calcareous sandstone and 0.7074 in mid-Pleistocene volcanic pyroclast. The 87Sr/86Sr ratios measured in plants growing on volcanic bedrock show time dependent increases in atmospheric deposition relative to bedrock weathering. The 87Sr/86Sr ratios measured in plants growing on renzina soils depends on precipitation. The spacing between bedrock 87Sr/86Sr ratios and plants is highest in wet conditions and decreases in dry conditions. The 87Sr/86Sr ratios measured in plants growing on terra rossa soils is relatively constant (0.7085) regardless of precipitation. Ligneous plants are typically closer to bedrock 87Sr/86Sr ratios than non-ligneous plants. Since the bioavailable 87Sr/86Sr ratios currently measured in the region reflect a mix of both exogenous and endogenous sources, changes in the relative contribution of exogenous sources can cause variation

  19. Stable isotope ratios as a tool in microbial forensics--part 3. Effect of culturing on agar-containing growth media.

    PubMed

    Kreuzer-Martin, Helen W; Chesson, Lesley A; Lott, Michael J; Ehleringer, James R

    2005-11-01

    Stable isotope ratios of hydrogen and oxygen in microbes have been shown to be functions of the corresponding isotope ratios of the water with which the culture medium was prepared, and thus to contain a potential geographic signal. Water can evaporate from agar (solid) media during culturing, changing its isotope ratios. Here we describe the effect of drying on the isotope ratios of water extracted from agar media and the H and O stable isotope ratios ratios of Bacillus subtilis spores cultured on agar. The delta2H vs delta18O relationship of water in Petri dish agar was surprisingly constant during evaporation regardless of the ambient relative humidity, making it possible to calculate the approximate isotope ratios of the original water, even in significantly evaporated agar. The H stable isotope ratios of spores cultured on agar remained relatively unchanged as the agar dried, but the O ratio became significantly enriched.

  20. Determining the geochemical structure of the mantle from surface isotope distribution patterns? Insights from Ne and He isotopes and abundance ratios

    NASA Astrophysics Data System (ADS)

    Stroncik, N.; Niedermann, S.; Schnabel, E.; Erzinger, J.

    2011-12-01

    It is a common procedure among geochemists to use surface distribution patterns of e.g. Sr, Nd, Pb or He isotopes of lavas erupted at oceanic islands to map the geochemical structure of the Earth's mantle. Advances in noble gas mass spectrometry within the last decade resulting in an increasing availability of Ne isotope data sets allow us to test the strength of this approach. 4He and 21Ne are coupled through the same parent nuclides and therefore should show analogous isotope distribution patterns. Here we present He and Ne fusion data of fresh olivines derived from Big Island, Hawaii, together with He and Ne fusion data of fresh glasses from the Easter Seamount Chain (ESC), indicating that the observed isotope distribution patterns are mainly controlled by melting and shallow mixing processes. He isotopic ratios of the investigated olivines vary from MORB-like (8 ± 1 RA) to ratios more typical for a primitive mantle source (up to 20 and 26 RA for Hawaii and the ESC, respectively; RA = atmospheric 3He/4He ratio of 1.39 x 10-6). In contrast, all Ne isotope data plot within error limits along the Loihi-Kilauea line in a Ne three-isotope diagram. The Loihi-Kilauea line is regarded to be typical for a primitive mantle source. Thus, the Ne isotope data are inconsistent with any kind of zoned plume model or even a heterogeneous mantle source. The combined He and Ne data show that these He and Ne isotope systematics are produced by a pre-degassing fractionation process and subsequent melt mixing. Basically, this process causes a He deficit in melts generated by the plume, as shown by 3He/22NeS below current estimates of solar or planetary composition and 4He/21Ne* lower than the production ratio, making the He isotopic composition more susceptible to changes than the Ne isotopic composition. This can best be explained by a model in which He is fractionated from Ne during formation of melts from a plume (or enriched parts of a plume) at low melting degrees, which

  1. Performance Of A Laser Based CO2 Isotope Ratio Infrared Spectrometer To Study Biosphere-Atmosphere Exchange

    NASA Astrophysics Data System (ADS)

    Jost, Hans-Juerg; Wapelhorst, Eric; Schlueter, Hans-Juergen; Kracht, Oliver; Radke, Jens; Hilkert, Andreas; Gangi, Laura; Bol, Roland; Brueggemann, Nicolas; Van Leeuwen, Charlotte; Meijer, Harro

    2014-05-01

    We are presenting results from a mid-infrared laser-based Isotope Ratio Infrared Spectrometers (IRIS) that is capable of simultaneously determining both δ18O and δ13C isotope ratios of carbon dioxide utilizing a simple, direct absorption approach with a robust multi pass cell and a cryogen free setup. A simulation of ambient measurement conditions with a 75 ppm per hour change in CO2 concentration from 350-650 ppm showed a precision of

  2. Effects of several variable factors on the isotope ratio by HRGC-MS.

    PubMed

    Sawamura, Masayoshi; Satake, Atsushi; Ueno, Takao; Une, Akitoshi; Ukeda, Hiroyuki

    2004-01-01

    In the isotope ratio (Ir) analysis using GC-MS, several variable factors in sampling incidental to any food analysis were investigated for yuzu fruit. The Irs of ten monoterpene hydrocarbons in yuzu essential oils from each of six fruiting positions of three trees were measured. The sign test following t-test of all the Ir values demonstrated that there was no significant difference between both sampling years of 2001 and 2002. There was also no significant variation in the Ir values among the three trees and six fruiting positions in the individual two years.

  3. Unusual stable isotope ratios in amino acid and carboxylic acid extracts from the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Epstein, S.; Krishnamurthy, R. V.; Cronin, J. R.; Pizzarello, S.; Yuen, G. U.

    1987-01-01

    The isotopic composition of hydrogen, nitrogen, and carbon in amino acid and monocarboxylic acid extracts from the Murchison meteorite has been determined. The unusually high D/H and N-15/N-14 ratios in the amino acid fraction are uniquely characteristic of known interstellar organic materials. The delta D value of the monocarboxylic acid fraction is lower but still consistent with an interstellar origin. These results confirm the extraterrestrial origin of both classes of compound and provide the first evidence suggesting a direct relationship between the massive organosynthesis occurring in interstellar clouds and the presence of prebiotic compounds in primitive planetary bodies.

  4. Stable nitrogen isotope ratios of bone collagen reflect marine and terrestrial components of prehistoric human diet

    SciTech Connect

    Schoeninger, M.J.; DeNiro, M.J.; Tauber, H.

    1983-06-24

    delta/sup 15/N values of bone collagen from Eskimos and from Northwst Coast Indians dependent on salmon fishing are about 10 per mil more positive than those from agriculturalists in historic times. Among prehistoric humans, two groups dependent on marine food sources show bone collagen delta/sup 15/N values that are 4 to 6 per mil more positive than those from two agricultural groups. The nitrogen isotope ratios of bone collagen from prehistoric inhabitants of Bahamas are anomalously low for reasons that relate to the biogeochemical cycle of nitrogen in coral reefs.

  5. Source Attribution of Cyanides using Anionic Impurity Profiling, Stable Isotope Ratios, Trace Elemental Analysis and Chemometrics

    SciTech Connect

    Mirjankar, Nikhil S.; Fraga, Carlos G.; Carman, April J.; Moran, James J.

    2016-01-08

    Chemical attribution signatures (CAS) for chemical threat agents (CTAs) are being investigated to provide an evidentiary link between CTAs and specific sources to support criminal investigations and prosecutions. In a previous study, anionic impurity profiles developed using high performance ion chromatography (HPIC) were demonstrated as CAS for matching samples from eight potassium cyanide (KCN) stocks to their reported countries of origin. Herein, a larger number of solid KCN stocks (n = 13) and, for the first time, solid sodium cyanide (NaCN) stocks (n = 15) were examined to determine what additional sourcing information can be obtained through anion, carbon stable isotope, and elemental analyses of cyanide stocks by HPIC, isotope ratio mass spectrometry (IRMS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), respectively. The HPIC anion data was evaluated using the variable selection methods of Fisher-ratio (F-ratio), interval partial least squares (iPLS), and genetic algorithm-based partial least squares (GAPLS) and the classification methods of partial least squares discriminate analysis (PLSDA), K nearest neighbors (KNN), and support vector machines discriminate analysis (SVMDA). In summary, hierarchical cluster analysis (HCA) of anion impurity profiles from multiple cyanide stocks from six reported country of origins resulted in cyanide samples clustering into three groups: Czech Republic, Germany, and United States, independent of the associated alkali metal (K or Na). The three country groups were independently corroborated by HCA of cyanide elemental profiles and corresponded to countries with known solid cyanide factories. Both the anion and elemental CAS are believed to originate from the aqueous alkali hydroxides used in cyanide manufacture. Carbon stable isotope measurements resulted in two clusters: Germany and United States (the single Czech stock grouped with United States stocks). The carbon isotope CAS is believed to

  6. Investigation of the isotopic ratio 129I/I in petrified wood.

    PubMed

    Jabbar, Tania; Steier, Peter; Wallner, Gabriele; Cichocki, Otto; Sterba, Johannes H

    2013-06-01

    In fossil specimens, measurements of the natural isotopic ratio (129)I/I may provide a method to estimate the age of sample. The motivation for measuring the isotopic composition ((129)I/I) of petrified wood samples collected from Austria was to check this feasibility. Alkaline fusion together with anion exchange was used to extract iodine from the sample. Typical sample size for this study was 10-90 g. An atomic ratio as low as 10(-14) was determined using accelerator mass spectrometry (AMS). Uranium concentrations measured by instrumental neutron activation analysis (INAA) and α-spectrometry were found to be less than 3 mg kg(-1), therefore the contribution from fissiogenic (129)I was small and an estimation of ages was based on the decrease of the initial ratio (due to decay of the cosmogenic (129)I in a closed system) after subtraction of the fissiogenic (129)I. The value of the prenuclear ratio is crucial for the use of the (129)I system for dating purposes in the terrestrial environment. From the preanthropogenic (initial) ratio of 1.5 × 10(-12) of the hydrosphere and the results of the present study for the samples from Altenburg (1.05 × 10(-12)) and Fuerwald (6.16 × 10(-13)), respective ages of 8 ± 2.2 and 20.2 ± 2.2 million years were derived. Since samples were collected from a stratum deposited in the Upper Oligocene/Ergerien period (~25-30 million years ago), it can be concluded that these isotopic ratios do not show ages but an elapsed time since fossil wood was isolated from mineral rich water. Paleontological investigation shows that samples from Altenburg had mixed characteristics of old and modern Tertiary plants, thus an origin from a younger stratum re-sedimented with Oligocene cannot be excluded. However, the sample from Drasenhofen reflects that the (129)I/I system might not always be suitable for the dating of petrified wood sample due to fixation of anthropogenic (129)I into surface fractures.

  7. A fast switching electrostatic deflector system for actinide isotopic ratio measurements

    NASA Astrophysics Data System (ADS)

    Zorko, Benjamin; Child, D. P.; Hotchkis, M. A. C.

    2010-04-01

    We have implemented a fast switching electrostatic system on the actinides beamline on the ANTARES accelerator at ANSTO, to improve the precision of analyses by accelerator mass spectrometry. This high-energy bouncing system is based on a pair of deflector plates, deflecting in the orbit plane, set at the entrance and exit of the analysing magnet. The design of deflector plates is unique, and it was modelled by SIMION in order to minimize field inhomogenity and fringe field effects. The pair of deflector plates are supplied by a high-voltage amplifier driven by an EPICS-enabled control unit, with two 4 W power supplies providing up to ±10 kV modulation. The high-energy bouncing system is synchronized with the existing low-energy bouncing system. To measure the isotopic ratio with the new system, the magnetic fields of the injector and analysing magnets are set to transmit selected isotopes along the beam line with zero voltage applied. The other isotopes of interest are transmitted by keeping the magnetic fields constant and modulating the voltages on the injector magnet chamber and on the high-energy deflector plates.

  8. Intra-Shell boron isotope ratios in benthic foraminifera: Implications for paleo-pH reconstructions

    NASA Astrophysics Data System (ADS)

    Rollion-Bard, C.; Erez, J.

    2009-12-01

    The boron isotope composition of marine carbonates is considered to be a seawater pH proxy. Nevertheless, the use of δ11B has some limitations: 1) the knowledge of fractionation factor (α4-3) between the two boron dissolved species (boric acid and borate ion), 2) the δ11B of seawater may have varied with time and 3) the amplitude of the "vital effects" of this proxy. Using secondary ion mass spectrometry (SIMS), we looked at the internal variability in the boron isotope ratio of the shallow water, symbionts bearing foraminiferan Amphistegina lobifera. Specimens were cultured at constant temperature (24±0.1 °C) in seawater with pH ranging between 7.90 and 8.45. We performed 6 to 8 measurements of δ11B in each foraminifera. Intra-shell boron isotopes show large variability with an upper threshold value of pH ~ 9. The ranges of the skeletal calculated pH values in different cultured foraminifera, show strong correlation with the culture pH values and may thus serve as proxy for pH in the past ocean.

  9. Drought and flood signals in subtropical estuaries recorded by stable isotope ratios in bivalve shells

    NASA Astrophysics Data System (ADS)

    Walther, B. D.; Rowley, J. L.

    2013-11-01

    Isotope ratios of carbon and oxygen recorded in biogenic carbonates can be effective proxies for ambient conditions in estuaries including salinity and temperature. Together, they have the potential to allow periods of drought and flooding to be identified in subtropical estuaries that receive stochastic and aperiodic delivery of freshwater inflow. We investigated the ability of δ13C and δ18O values in shell increments from the eastern oyster Crassostrea virginica sampled from subtropical estuaries in the western Gulf of Mexico to indicate differences in temperature and salinity dynamics at fine spatial scales. Oyster shells at locations that experienced both hypersalinity during droughts and dramatic decreases in salinity during floods showed distinct variations in shell δ13C and δ18O values that reflected local salinity conditions. In contrast, oysters at sites where no major salinity fluctuation occurred showed only seasonal fluctuations in isotopes reflecting temperature and possibly feeding patterns. Further, similar isotopic patterns were observed across multiple individuals from each site. Our results show that δ13C and δ18O values in shells measured together provide a powerful method to identify droughts and floods in subtropical estuaries and therefore extend records of dynamic inflow to these stressed ecosystems.

  10. Effects of volatilization on carbon and hydrogen isotope ratios of MTBE.

    PubMed

    Kuder, Tomasz; Philp, Paul; Allen, Jon

    2009-03-15

    Contaminant attenuation studies utilizing CSIA (compound-specific isotope analysis) routinely assume that isotope effects (IEs) result only from degradation. Experimental results on MTBE behavior in diffusive volatilization and dynamic vapor extraction show measurable changes in the isotope ratios of the MTBE remaining in the aqueous or nonaqueous phase liquid (NAPL) matrix. A conceptual model for interpretation of those IEs is proposed, based on the physics of liquid-air partitioning. Normal or inverse IEs were observed for different volatilization scenarios. The range of carbon enrichment factors (epsilon) was from +0.7 per thousand (gasoline vapor extraction) to -1 per thousand (diffusive volatilization of MTBE from gasoline), the range of hydrogen epsilon was from +7 per thousand (gasoline vapor extraction) to -12 per thousand (air sparging of aqueous MTBE). The observed IEs are lower than those associated with MTBE degradation. However, under a realistic scenario for MTBE vapor removal, their magnitude is within the detection limits of CSIA. The potential for interference of those IEs is primarily in confusing the interpretation of samples with a small extent of fractionation and where only carbon CSIA data are available. The IEs resulting from volatilization and biodegradation, respectively, can be separated by combined carbon and hydrogen 2D-CSIA.

  11. Spatial and temporal evolution of lead isotope ratios in the North Atlantic Ocean between 1981 and 1989

    NASA Astrophysics Data System (ADS)

    Weiss, Dominik; Boyle, Edward A.; Wu, Jingfeng; Chavagnac, ValéRie; Michel, Anna; Reuer, Matthew K.

    2003-10-01

    Lead concentrations and isotope ratios were measured in North Atlantic surface water samples collected in 1981 (29°-79°N, 6°E-49°W) and in 1989 (23°-39°N, 29°-68°W). In the early 1980s, 206Pb/207Pb ratios in the North African Basin averaged 1.193 ± 0.005 (1 σ). Similar radiogenic ratios within the level of analytical precision (average 0.29%) were found in the Labrador and Iceland Basins (1.198 ± 0.006) and in the Norwegian Sea (1.196 ± 0.008). These radiogenic mixed layer signatures along with atmospheric global lead emission patterns suggest that most North Atlantic lead in the early 1980s was derived from North American leaded gasoline. Samples in the East Iberian Basin near Portugal and France showed lower 206Pb/207Pb ratios, between 1.167 and 1.182, indicating a significant influence of less radiogenic atmospheric lead transported from Europe and possibly the influence of the Rio Tinto acid mine drainage very close to shore in the Gulf of Cadiz. [Pb] across the entire North Atlantic Basin ranged between 54 and 145 pmol/kg, with the lowest values (54-74 pmol/kg) found at high latitudes (>65°N). In the late 1980s, surface waters in the western subtropical North Atlantic (North American Basin/Sargasso Sea, >47°W) and in the eastern subtropical North Atlantic (North African Basin/Central Iberian Basin, <45°W) showed very similar 206Pb/207Pb signatures with little zonal variation, ranging from 1.177 to 1.192. Lead concentrations ranged between 47 and 137 pmol/kg, increasing slightly from west to east. South of 25°N in the equatorial North Atlantic, crossing the subtropical/tropical surface water boundary, the 206Pb/207Pb seawater signatures were significantly less radiogenic (1.170-1.175) and concentrations were lower (≤51 pmol/kg). This difference suggests a relative increase in the atmospheric lead supply from the western Mediterranean/North African continent via Trade Easterlies and illustrates the effective barrier between the subtropical

  12. Converting isotope ratios to diet composition - the use of mixing models - June 2010

    EPA Science Inventory

    One application of stable isotope analysis is to reconstruct diet composition based on isotopic mass balance. The isotopic value of a consumer’s tissue reflects the isotopic values of its food sources proportional to their dietary contributions. Isotopic mixing models are used ...

  13. Atmospheric Trace Gas Abundances and Stable Isotope Ratios via IR-LIF

    NASA Technical Reports Server (NTRS)

    Blake, Geoffrey A.

    2004-01-01

    We propose to develop new technologies with support provided by PIDDP that will enable the in situ measurements of abundances and stable isotope ratios in important radiatively and biogenically active gases such as carbon dioxide, carbon monoxide, water, methane, nitrous oxide, and hydrogen sulfide to very high precision (0.1 per mil or better for the isotopic ratios, for example). Such measurements, impossible at present, could provide pivotal new constraints on the global (bio)geochemical budgets of these critical species, and could also be used to examine the dynamics of atmospheric transport on Mars, Titan, and other solar system bodies. We believe the combination of solid state light sources with imaging of the IR laser induced fluorescence (IR-LIF) via newly available detector arrays will make such in situ measurements possible for the first time. Even under ambient terrestrial conditions, the LIF yield from vibrational excitation of species such as water and carbon dioxide should produce emission measures well in excess of ten billion photons/sec from samples volumes of order 1 c.c. These count rates can, in principle, yield detection limits into the sub-ppt range that are required for the in situ isotopic study of atmospheric trace gases. While promising, such technologies are relatively immature, but developing rapidly, and there are a great many uncertainties regarding their applicability to in situ IR-LIF planetary studies. We therefore feel PIDDP support will be critical to developing these new tools, and propose a three-year program to combine microchip near-IR lasers with low background detection axes and state-of-the-art HgCdTe detectors developed for astronomical spectroscopy to investigate the sensitivity of IR-LIF under realistic planetary conditions, to optimize the optical pumping and filtering schemes for important species, and to apply the spectrometer to the non-destructive measurement of stable isotopes in a variety of test samples. These

  14. Fukushima Daiichi reactor source term attribution using cesium isotope ratios from contaminated environmental samples

    SciTech Connect

    Snow, Mathew S.; Snyder, Darin C.; Delmore, James E.

    2016-01-18

    Source term attribution of environmental contamination following the Fukushima Daiichi Nuclear Power Plant (FDNPP) disaster is complicated by a large number of possible similar emission source terms (e.g. FDNPP reactor cores 1–3 and spent fuel ponds 1–4). Cesium isotopic analyses can be utilized to discriminate between environmental contamination from different FDNPP source terms and, if samples are sufficiently temporally resolved, potentially provide insights into the extent of reactor core damage at a given time. Rice, soil, mushroom, and soybean samples taken 100–250 km from the FDNPP site were dissolved using microwave digestion. Radiocesium was extracted and purified using two sequential ammonium molybdophosphate-polyacrylonitrile columns, following which 135Cs/137Cs isotope ratios were measured using thermal ionization mass spectrometry (TIMS). Results were compared with data reported previously from locations to the northwest of FDNPP and 30 km to the south of FDNPP. 135Cs/137Cs isotope ratios from samples 100–250 km to the southwest of the FDNPP site show a consistent value of 0.376 ± 0.008. 135Cs/137Cs versus 134Cs/137Cs correlation plots suggest that radiocesium to the southwest is derived from a mixture of FDNPP reactor cores 1, 2, and 3. Conclusions from the cesium isotopic data are in agreement with those derived independently based upon the event chronology combined with meteorological conditions at the time of the disaster. In conclusion, cesium isotopic analyses provide a powerful tool for source term discrimination of environmental radiocesium contamination at the FDNPP site. For higher precision source term attribution and forensic determination of the FDNPP core conditions based upon cesium, analyses of a larger number of samples from locations to the north and south of the FDNPP site (particularly time-resolved air filter samples) are needed

  15. The relationship between needle sugar carbon isotope ratios and tree rings of larch in Siberia.

    PubMed

    Rinne, K T; Saurer, M; Kirdyanov, A V; Loader, N J; Bryukhanova, M V; Werner, R A; Siegwolf, R T W

    2015-11-01

    Significant gaps still exist in our knowledge about post-photosynthetic leaf level and downstream metabolic processes and isotopic fractionations. This includes their impact on the isotopic climate signal stored in the carbon isotope composition (δ(13)C) of leaf assimilates and tree rings. For the first time, we compared the seasonal δ(13)C variability of leaf sucrose with intra-annual, high-resolution δ(13)C signature of tree rings from larch (Larix gmelinii Rupr.). The trees were growing at two sites in the continuous permafrost zone of Siberia with different growth conditions. Our results indicate very similar low-frequency intra-seasonal trends of the sucrose and tree ring δ(13)C records with little or no indication for the use of 'old' photosynthates formed during the previous year(s). The comparison of leaf sucrose δ(13)C values with that in other leaf sugars and in tree rings elucidates the cause for the reported (13)C-enrichment of sink organs compared with leaves. We observed that while the average δ(13)C of all needle sugars was 1.2‰ more negative than δ(13)C value of wood, the δ(13)C value of the transport sugar sucrose was on an average 1.0‰ more positive than that of wood. Our study shows a high potential of the combined use of compound-specific isotope analysis of sugars (leaf and phloem) with intra-annual tree ring δ(13)C measurements for deepening our understanding about the mechanisms controlling the isotope variability in tree rings under different environmental conditions.

  16. The stability and calibration of water vapor isotope ratio measurements during long-term deployments

    NASA Astrophysics Data System (ADS)

    Bailey, A.; Noone, D.; Berkelhammer, M.; Steen-Larsen, H. C.; Sato, P.

    2015-05-01

    With the recent advent of commercial laser absorption spectrometers, field studies measuring stable isotope ratios of hydrogen and oxygen in water vapor have proliferated. These pioneering analyses have provided invaluable feedback about best strategies for optimizing instrumental accuracy, yet questions still remain about instrument performance and calibration approaches for multi-year field deployments. With clear scientific potential for using these instruments to carry out long-term monitoring of the hydrological cycle, this study examines the long-term stability of the isotopic biases associated with three cavity-enhanced laser absorption spectrometers - calibrated with different systems and approaches - at two remote field sites: Mauna Loa Observatory, Hawaii, USA, and Greenland Environmental Observatory, Summit, Greenland. The analysis pays particular attention to the stability of measurement dependencies on water vapor concentration and also evaluates whether these so-called concentration-dependences are sensitive to statistical curve-fitting choices or measurement hysteresis. The results suggest evidence of monthly-to-seasonal concentration-dependence variability - which likely stems from low signal-to-noise at the humidity-range extremes - but no long-term directional drift. At Mauna Loa, where the isotopic analyzer is calibrated by injection of liquid water standards into a vaporizer, the largest source of inaccuracy in characterizing the concentration-dependence stems from an insufficient density of calibration points at low humidity. In comparison, at Greenland, the largest source of inaccuracy is measurement hysteresis associated with interactions between the reference vapor, generated by a custom dew point generator (DPG), and the sample tubing. Nevertheless, prediction errors associated with correcting the concentration-dependence are small compared to total measurement uncertainty. At both sites, a dominant source of uncertainty is instrumental

  17. Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry.

    PubMed

    Merritt, D A; Freeman, K H; Ricci, M P; Studley, S A; Hayes, J M

    1995-07-15

    Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T < 1050 degrees C if gas-phase O2 is not added. For all compounds tested except CH4, equivalent isotopic results are provided by CuO at 850 degrees C, NiO + O2 (gas-phase mole fraction, 10(-3)) at 1050 degrees C and NiO at 1150 degrees C. The combustion interface did not contribute additional analytical uncertainty, thus observed standard deviations of 13C/12C ratios were within a factor of 2 of shot-noise limits. For combustion and isotopic analyses of CH4, in which quantitative combustion required T approximately 950 degrees C, NiO-based systems are preferred, and precision is approximately 2 times lower than that observed for other analytes. Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer.

  18. Amino acid compositions in heated carbonaceous chondrites and their compound-specific nitrogen isotopic ratios

    NASA Astrophysics Data System (ADS)

    Chan, Queenie Hoi Shan; Chikaraishi, Yoshito; Takano, Yoshinori; Ogawa, Nanako O.; Ohkouchi, Naohiko

    2016-01-01

    A novel method has been developed for compound-specific nitrogen isotope compositions with an achiral column which was previously shown to offer high precision for nitrogen isotopic analysis. We applied the method to determine the amino acid contents and stable nitrogen isotopic compositions of individual amino acids from the thermally metamorphosed (above 500 °C) Antarctic carbonaceous chondrites Ivuna-like (CI)1 (or CI-like) Yamato (Y) 980115 and Ornans-like (CO)3.5 Allan Hills (ALH) A77003 with the use of gas chromatography/combustion/isotope ratio mass spectrometry. ALHA77003 was deprived of amino acids due to its extended thermal alteration history. Amino acids were unambiguously identified in Y-980115, and the δ15N values of selected amino acids (glycine +144.8 ‰; α-alanine +121.2 ‰) are clearly extraterrestrial. Y-980115 has experienced an extended period of aqueous alteration as indicated by the presence of hydrous mineral phases. It has also been exposed to at least one post-hydration short-lived thermal metamorphism. Glycine and alanine were possibly produced shortly after the accretion event of the asteroid parent body during the course of an extensive aqueous alteration event and have abstained from the short-term post-aqueous alteration heating due to the heterogeneity of the parent body composition and porosity. These carbonaceous chondrite samples are good analogs that offer important insights into the target asteroid Ryugu of the Hayabusa-2 mission, which is a C-type asteroid likely composed of heterogeneous materials including hydrated and dehydrated minerals.

  19. Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry

    NASA Technical Reports Server (NTRS)

    Merritt, D. A.; Freeman, K. H.; Ricci, M. P.; Studley, S. A.; Hayes, J. M.

    1995-01-01

    Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T < 1050 degrees C if gas-phase O2 is not added. For all compounds tested except CH4, equivalent isotopic results are provided by CuO at 850 degrees C, NiO + O2 (gas-phase mole fraction, 10(-3)) at 1050 degrees C and NiO at 1150 degrees C. The combustion interface did not contribute additional analytical uncertainty, thus observed standard deviations of 13C/12C ratios were within a factor of 2 of shot-noise limits. For combustion and isotopic analyses of CH4, in which quantitative combustion required T approximately 950 degrees C, NiO-based systems are preferred, and precision is approximately 2 times lower than that observed for other analytes. Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer.

  20. On-line systems for continuous water and gas isotope ratio measurements.

    PubMed

    Huber, Christof; Leuenberger, Markus

    2005-09-01

    New continuous on-line techniques for water and air extracted from ice cores are developed. Water isotope ratio determination on any of the water phases (water vapour, water, ice) is of great relevance in different research fields, such as climate and paleoclimate studies, geological surveys, and hydrological studies. The conventional techniques for water isotopes are available in different layouts but all of them are rather time-consuming. Here we report new fast on-line techniques that process water as well as ice samples. The analysis time is only approximately 5 min per sample which includes equilibration and processing. Measurement precision and accuracy are better than 0.1 per thousand and 1 per thousand for delta18O and deltaD, respectively, comparable to conventional techniques. The new on-line techniques are able to analyze a wide range of aqueous samples. This allows, for the first time, to make continuous isotope measurements on ice cores. Similarly, continuous and fast analysis of aqueous samples can be of great value for hydrological, geological and perhaps medical applications.Furthermore, a new technique for the on-line analysis of air isotopes extracted from ice cores is developed. This technique allows rapid analyses with high resolution of the main air components nitrogen, oxygen, and argon. Measurement precision is comparable to precisions obtained by conventional techniques. It is now possible to measure delta15N and delta18O(atm) over entire ice cores helping to synchronize chronologies, to assess gas age-ice age differences, and to calibrate the paleothermometry for rapid temperature changes. This new on-line air extraction and analyzing technique complements the water methods in an ideal way as it separates the air from the melt-water of an ice sample. The remaining water waste flux can directly be analyzed by the water methods.

  1. Stable Nitrogen and Carbon Isotope Ratios Indicate Traditional and Market Food Intake in an Indigenous Circumpolar Population123

    PubMed Central

    Nash, Sarah H.; Bersamin, Andrea; Kristal, Alan R.; Hopkins, Scarlett E.; Church, Rebecca S.; Pasker, Renee L.; Luick, Bret R.; Mohatt, Gerald V.; Boyer, Bert B.; O’Brien, Diane M.

    2012-01-01

    The transition of a society from traditional to market-based diets (termed the nutrition transition) has been associated with profound changes in culture and health. We are developing biomarkers to track the nutrition transition in the Yup’ik Eskimo population of Southwest Alaska based on naturally occurring variations in the relative abundances of carbon and nitrogen stable isotopes (δ15N and δ13C values). Here, we provide three pieces of evidence toward the validation of these biomarkers. First, we analyzed the δ15N and δ13C values of a comprehensive sample of Yup’ik foods. We found that δ15N values were elevated in fish and marine mammals and that δ13C values were elevated in market foods containing corn or sugar cane carbon. Second, we evaluated the associations between RBC δ15N and δ13C values and self-reported measures of traditional and market food intake (n = 230). RBC δ15N values were correlated with intake of fish and marine mammals (r = 0.52; P < 0.0001). RBC δ13C values were correlated with intake of market foods made from corn and sugar cane (r = 0.46; P < 0.0001) and total market food intake (r = 0.46; P < 0.0001). Finally, we assessed whether stable isotope ratios captured population-level patterns of traditional and market intake (n = 1003). Isotopic biomarkers of traditional and market intake were associated with age, community location, sex, and cultural identity. Self-report methods showed variations by age and cultural identity only. Thus, stable isotopes show potential as biomarkers for monitoring dietary change in indigenous circumpolar populations. PMID:22157543

  2. Progress in quantifying rates and product ratios of microbial denitrification using stable isotope approaches

    NASA Astrophysics Data System (ADS)

    Well, Reinhard; Buchen, Caroline; Giesemann, Anette; Lewicka-Szczebak, Dominika; Rohe, Lena; Flessa, Heinz

    2015-04-01

    Although it is known since long that microbial denitrification plays a central role in N cycling in soils due to loss of nutrient N, emissions of N2O and lowering of N leaching, few data at the field scale are available due to the difficulty in measurement. In recent years, stable isotope signatures of N2O such as δ18O, average δ15N (δ15Nbulk) and 15N site preference (SP = difference in δ15N between the central and peripheral N positions of the asymmetric N2O molecule) have been used to constrain the atmospheric N2O budget and to characterize N2O turnover processes including N2O production and reduction by microbial denitrification. However, the use of this approach to study N2O dynamics in soils requires knowledge of isotope fractionation factors for the various partial processes involved, e.g. N2O production by nitrification or fungal/bacterial denitrification, and N2O reduction by bacterial denitrification. Here we present recent progress on the principles of isotope fractionation modeling to estimate N2O reduction and on the role of microbial groups and their specific impact on isotope values. Moreover, we report and discuss approaches to determine isotope values of produced N2O prior to its reduction as well as enrichment factors of N2O reduction. Finally, a variety of results from lab and field studies will be shown were N2O reduction estimates by isotope fractionation modeling are validated by independent measurements using 15N tracing or He/O2 incubations. Methodical improvements to increase sensitivity of the 15N tracing approach will be briefly addressed. We conclude that up to now SP of soil-emitted N2O proved to be suitable to constrain the product ratio of denitrification if N2O fluxes are dominated by bacterial denitrification. Although this approach is not yet precise enough for robust quantification of N2 fluxes, improved precision can be obtained in future, if further progress in understanding the control of fractionation factors of production

  3. Stable isotope ratios of atmospheric CO_{2} and CH_{4} over Siberia measured at ZOTTO

    NASA Astrophysics Data System (ADS)

    Timokhina, Anastasiya; Prokushkin, Anatily; Lavric, Jost; Heimann, Martin

    2016-04-01

    The boreal and arctic zones of Siberia housing the large amounts of carbon stored in the living biomass of forests and wetlands, as well as in soils and specifically permafrost, play a crucial role in earth's global carbon cycle. The long-term studies of greenhouse gases (GHG) concentrations are important instruments to analyze the response of these systems to climate warming. In parallel to GHG observations, the measurements of their stable isotopic composition can provide useful information for distinguishing contribution of individual GHG source to their atmospheric variations, since each source has its own isotopic signature. In this study we report first results of laboratory analyses of the CO2 and CH4 concentrations, the stable isotope ratio of δ13C-CO2, δ18O-CO2, δ13C-CH4, δD-CH4 measured in one-liter glass flasks which were obtained from 301 height of ZOTTO (Zotino Tall Tower Observatory, near 60° N, 90° E, about 20 km west of the Yenisei River) during 2008 - 2013 and 2010 - 2013 for stable isotope composition of CO2 and CH4. The magnitudes of δ13C-CO2 and δ18O-CO2 in a seasonal cycle are -1.4±0.1‰ (-7.6 - -9.0‰) and -2.2±0.2‰ (-0.1 - -2.3‰), respectively. The δ13C-CO2 seasonal pattern opposes the CO2 concentrations, with a gradual enrichment in heavy isotope occurring during May - July, reflecting its discrimination in photosynthesis, and further depletion in August - September as photosynthetic activity decreases comparatively to ecosystem respiration. Relationship between the CO2 concentrations and respective δ13C-CO2 (Keeling plot) reveals isotopic source signature for growing season (May - September) -27.3±1.4‰ and -30.4±2.5‰ for winter (January - March). The behavior of δ18O-CO2 associated with both high photosynthetic rate in the June (enrichment of atmospheric CO2 by 18O as consequence of CO2 equilibrium with "heavy" leaf water) and respiratory activity of forest floor in June - October (depletion of respired CO2 by 18O

  4. Water isotope ratio (δ2H and δ18O) measurements in atmospheric moisture using an optical feedback cavity enhanced absorption laser spectrometer

    NASA Astrophysics Data System (ADS)

    Iannone, Rosario Q.; Romanini, Daniele; Cattani, Olivier; Meijer, Harro A. J.; Kerstel, Erik R. Th.

    2010-05-01

    Water vapor isotopes represent an innovative and excellent tool for understanding complex mechanisms in the atmospheric water cycle over different time scales, and they can be used for a variety of applications in the fields of paleoclimatology, hydrology, oceanography, and ecology. We use an ultrasensitive near-infrared spectrometer, originally designed for use on airborne platforms in the upper troposphere and lower stratosphere, to measure the water deuterium and oxygen-18 isotope ratios in situ, in ground-level tropospheric moisture, with a high temporal resolution (from 300 s down to less than 1 s). We present some examples of continuous monitoring of near-surface atmospheric moisture, demonstrating that our infrared laser spectrometer could be used successfully to record high-concentration atmospheric water vapor mixing ratios in continuous time series, with a data coverage of ˜90%, interrupted only for daily calibration to two isotope ratio mass spectrometry-calibrated local water standards. The atmospheric data show that the water vapor isotopic composition exhibits a high variability that can be related to weather conditions, especially to changes in relative humidity. Besides, the results suggest that observed spatial and temporal variations of the stable isotope content of atmospheric water vapor are strongly related to water vapor transport in the atmosphere.

  5. Detection of exogenous GHB in blood by gas chromatography-combustion-isotope ratio mass spectrometry: implications in postmortem toxicology.

    PubMed

    Saudan, Christophe; Augsburger, Marc; Kintz, Pascal; Saugy, Martial; Mangin, Patrice

    2005-01-01

    Because GHB (gamma-hydroxybutyrate) is present in both blood and urine of the general population, toxicologists must be able to discriminate between endogenous levels and a concentration resulting from exposure. In this paper, we propose a procedure for the detection of exogenous GHB in blood by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Following liquid-liquid and solid-phase extractions, GHB is derivatized to GHB di-TMS before analysis by GC-C-IRMS. Significant differences in the carbon isotopic ratio (delta(13)C-values > 13.5 per thousand) were found between endogenous and synthetic GHB. Indeed, for postmortem blood samples with different GHB concentrations (range: 13.8-86.3 mg/L), we have obtained GHB delta(13)C-values ranging from -20.6 to -24.7 per thousand, whereas delta(13)C-values for the GHB from police seizure were in the range -38.2 to -50.2 per thousand. In contrast to the use of cut-off concentrations for positive postmortem blood GHB concentrations, this method should provide an unambiguous indication of the drug origin.

  6. Stable isotope ratios in atmospheric CH4: Implications for seasonal sources and sinks

    NASA Astrophysics Data System (ADS)

    Tyler, Stanley C.; Rice, Andrew L.; Ajie, Henry O.

    2007-02-01

    We report δD and δ13C measurements of atmospheric CH4 from air samples collected from two locations in the United States. They are the mid continental site Niwot Ridge, Colorado (40°N, 105°W), and a Pacific coastal site receiving strong westerlies, Montaña de Oro, California (35°N, 121°W). Data from multiyear approximately bimonthly sampling provide information relating seasonal cycling of CH4 sources and sinks in background air, record long-term trends in CH4 mixing and isotope ratio related to the atmospheric CH4 loading, and may indicate regional CH4 sources. At Niwot Ridge, δD-CH4 averaged -93.1 ± 3.0‰ from 1999 to 2001, while δ13C-CH4 averaged -47.22 ± 0.13‰ from 1995 to 2001 with distinct seasonal cycles in both isotope ratios. At Montaña de Oro, atmospheric CH4 was observed to be more depleted in 13C and D: Measured δD-CH4 averaged -97.3 ± 3.7‰ from 2000 to 2001, while δ13C-CH4 averaged -47.26 ± 0.17‰ from 1996 to 2001, and seasonal cycles were larger than those observed at Niwot Ridge. Mixing ratios observed at Montaña de Oro were higher on average than at Niwot Ridge. At both sites, δ13C-CH4 was found to correlate poorly with mixing ratio, an indication that varying CH4 sources are partly responsible for the δ13C-CH4 seasonal signal. In contrast, a strong anticorrelation exists between δD-CH4 and mixing ratio, with maxima and minima approximately 6 months out of phase, indicating a sensitivity of δD to sink processes. The dual isotopic constraint to atmospheric CH4 seasonality implies that these midlatitude sites are annually influenced by a 13C-enriched CH4 source(s) seasonally increasing in late spring and a 13C-depleted CH4 source(s) seasonally increasing in late summer or early fall.

  7. Predictions of oxygen isotope ratios in stars and of oxygen-rich interstellar grains in meteorites

    NASA Astrophysics Data System (ADS)

    Boothroyd, Arnold I.; Sackmann, I.-Juliana; Wasserburg, G. J.

    1994-07-01

    We carried out detailed, self-consistent calculations for stars from 1 to 9 solar mass over a wide range of metallicities, following the evolution and nucleosynthesis from the pre-main sequence to the asymptotic giant branch (AGB), in order to provide a self-consistent grid for evaluating stellar oxygen isotopic variations. These were calculated for first and second dredge-up, and for some masses also for third dredge-up and 'hot bottom' convective envelope burning on the AGB. We demonstrate that 0-16/0-17 in red giant envelopes is primarily a function of the star's mass, while 0-16/0-18 is primarily a function of the initial composition. Uncertainties in the 0-17-destruction rate have no effect on the 0-16/0-17 ratio for stars from 1 to 2.5 solar mass, but do affect the ratios for higher masses: the stellar 0-16/0-17 observations are consistent with the Landre et al. (1990) rates using f = 0.2 for 0-17(p,gamma) F-18 and -17(p. alpha) N-14, and with the Caughlan & Fowler (1988) rates using f approximately equals 1. The stellar 0-16/0-18 observations require f approximately equals 0 in the Caughlan & Fowler 0-18(p, alpha) N-15 rate. First dredge-up has the largest effect on the oxygen isotope ratios, decreasing 0-16/0-17 significantly from the initial value and increasing 0-16/0-18 slightly. Second and third dredge-up have only minor effects for solar metallicity stars. The absence of very low observed 0-16/0-18 ratios is consistent with a major increase in the 0-18(alpha, gamma) Ne-22 rate over the Caughlan & Fowler (1988) value. Hot bottom burning in stars above about 5 solar mass can cause a huge increase in 0-16/0-18 to approximately greater than 106, and possibly a significant decrease in 0-16/0-17; these are accompanied by a huge increase in Li-7 and a value of C-12/C-13 approximately = 3. The oxygen isotope ratios in the Al203 grains (Orgueil grain B, the Murchison 83-5 grain, and the new Bishunpur B39 grain) can be accounted for if they originated in stars

  8. Precise determination of atomic g-factor ratios from a dual isotope magneto-optical trap

    SciTech Connect

    Chan, I.; Barrett, B.; Kumarakrishnan, A.

    2011-09-15

    We demonstrate a technique, for carrying out precise measurements of atomic g-factor ratios, which relies on measurements of Larmor oscillations from coherences between magnetic sublevels in the ground states of {sup 85}Rb and {sup 87}Rb atoms confined in a dual isotope magneto-optical trap. We show that a measurement of g{sub F}{sup (87)}/g{sub F}{sup (85)} with a resolution of 0.69 parts per 10{sup 6} is possible by recording the ratio of Larmor frequencies in the presence of a constant magnetic field. This represents the most precise single measurement of g{sub F}{sup (87)}/g{sub F}{sup (85)} without correcting for systematic effects.

  9. Fractionation in position-specific isotope composition during vaporization of environmental pollutants measured with isotope ratio monitoring by ¹³C nuclear magnetic resonance spectrometry.

    PubMed

    Julien, Maxime; Parinet, Julien; Nun, Pierrick; Bayle, Kevin; Höhener, Patrick; Robins, Richard J; Remaud, Gérald S

    2015-10-01

    Isotopic fractionation of pollutants in terrestrial or aqueous environments is a well-recognized means by which to track different processes during remediation. As a complement to the common practice of measuring the change in isotope ratio for the whole molecule using isotope ratio monitoring by mass spectrometry (irm-MS), position-specific isotope analysis (PSIA) can provide further information that can be exploited to investigate source and remediation of soil and water pollutants. Position-specific fractionation originates from either degradative or partitioning processes. We show that isotope ratio monitoring by (13)C NMR (irm-(13)C NMR) spectrometry can be effectively applied to methyl tert-butylether, toluene, ethanol and trichloroethene to obtain this position-specific data for partitioning. It is found that each compound exhibits characteristic position-specific isotope fractionation patterns, and that these are modulated by the type of evaporative process occurring. Such data should help refine models of how remediation is taking place, hence back-tracking to identify pollutant sources.

  10. Effects of shock and Martian alteration on Tissint hydrogen isotope ratios and water content

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.; Huss, G. R.; Nagashima, K.; Taylor, G. J.; Stöffler, D.; Smith, C. L.; Lee, M. R.

    2017-03-01

    The Tissint meteorite, a picritic shergottite, fell to Earth in Morocco on the 18th of July 2011, and is only the fifth Martian meteorite witnessed to fall. Hydrogen isotope ratios and water contents are variable within different minerals in Tissint. Ringwoodite and shock melt pockets contain elevated D/H ratios relative to terrestrial values (δD = 761-4224‰). These high ratios in recrystallized phases indicate significant implantation of hydrogen from the D-rich Martian atmosphere during shock. In contrast, although olivine has detectable water abundances (230-485 ppm), it exhibits much lower D/H ratios (δD = +88 to -150‰), suggesting this water was not implanted from the Martian atmosphere. The minimal terrestrial weathering experienced by Tissint gives confidence that the olivine-hosted water has a Martian origin, but its high concentration indicates direct inheritance from the parental melt is improbable, especially given the low pressure of olivine crystallisation. Incorporation of a low δD crustal fluid, or deuteric alteration during crystallisation, could explain the relatively high water contents and low D/H ratios in Tissint olivine.

  11. Ammonia 15N/14N Isotope Ratio in the Jovian Atmosphere

    NASA Technical Reports Server (NTRS)

    Mahaffy, P.R.; Niemann, H. B.; Atreya, S. K.; Wong, M. H.; Owen, T. C; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Data from the Galileo Probe Mass Spectrometer has been used to derive the N-15/N-14 isotope ratio in ammonia at Jupiter. Although the mass spectral interference from the water contribution to 18 amu makes an accurate derivation of the (N-15)H3/(N-14)H3 ratio difficult from measurements of the singly ionized signals at 18 and 17 amu, this interference is not present in the doubly charged 8.5 and 9.0 amu signals from (N-14)H3++ and (N-15)H3++ respectively. Although the count rate from the 9 amu signal is low during the direct sampling of the atmosphere, the ammonia signal was considerably enhanced during the first enrichment cell (EC1) experiment that measured gas sampled between 0.8 and 2.8 bar. Count rates at 9 amu in the EC1 experiment reach 60/second and measure ammonia sampled from 0.88 to 2.8 bar. In the EC1 measurements the 8.5 amu signal is not measured directly, but can be calculated from the ammonia contribution to 17 amu and the ratio of NH3 ions of a double to single charged observed during a high resolution mass scan taken near the end of the descent. The high resolution scan gives this ratio from ammonia sampled much deeper in the atmosphere. These results are described and compared with Infrared Space Observatory-Short Wavelength Spectrometer (ISO-SWS) observations that give this ratio at 400 mbar.

  12. Authenticity of carbon dioxide bubbles in French ciders through multiflow-isotope ratio mass spectrometry measurements.

    PubMed

    Gaillard, Laetitia; Guyon, Francois; Salagoïty, Marie-Hélène; Médina, Bernard

    2013-12-01

    A procedure to detect whether carbon dioxide was added to French ciders has been developed. For this purpose, an optimised and simplified method is proposed to determine (13)C/(12)C isotope ratio of carbon dioxide (δ(13)C) in ciders. Three critical steps were checked: (1) influence of atmospheric CO2 remaining in the loaded vial, (2) impact of helium flush, (3) sampling speed. This study showed that atmospheric CO2 does not impact the measurement, that helium flush can lead to isotopic fractionation and finally, that a fractionation occurs only 5h after bottle opening. The method, without any other preparation, consists in sampling 0.2 mL of cold (4 °C) cider in a vial that is passed in an ultrasonic bath for 10 min at room temperature to enhance cider de-carbonation. The headspace CO2 is then analysed using the link Multiflow®-isotope ratio mass spectrometer. Each year, a data bank is developed by fermenting authentic apples juices in order to control cider authenticity. Over a four year span (2008-2011), the CO2 produced during the fermentation step was studied. This set of 61 authentic ciders, from various French production areas, was used to determine a δ(13)C value range of -22.59±0.92‰ for authentic ciders CO2 bubbles. 75 commercial ciders were analysed with this method. Most of the samples analysed present a gas δ(13)C value in the expected range. Nevertheless, some ciders have δ(13)C values outside the 3σ limit, revealing carbonation by technical CO2. This practice is not allowed for organic, "Controlled Appellation of Origin" ciders and ciders specifying natural carbonation on the label.

  13. The global methane cycle: isotopes and mixing ratios, sources and sinks.

    PubMed

    Bréas, O; Guillou, C; Reniero, F; Wada, E

    2001-01-01

    A review of the global cycle of methane is presented with emphasis on its isotopic composition. The history of methane mixing ratios, reconstructed from measurements of air trapped in ice-cores is described. The methane record now extends back to 420 kyr ago in the case of the Vostok ice cores from Antarctica. The trends in mixing ratios and in delta13C values are reported for the two Hemispheres. The increase of the atmospheric methane concentration over the past 200 years, and by 1% per year since 1978, reaching 1.7 ppmv in 1990 is underlined. The various methane sources are presented. Indeed the authors describe the methane emissions by bacterial activity under anaerobic conditions in wet environments (wetlands, bogs, tundra, rice paddies), in ruminant stomachs and termite guts, and that originating from fossil carbon sources, such as biomass burning, coal mining, industrial losses, automobile exhaust, sea floor vent, and volcanic emissions. Furthermore, the main sinks of methane in the troposphere, soils or waters via oxidation are also reported, and the corresponding kinetic isotope effects.

  14. Concentrations and isotope ratios of carbon, nitrogen and sulfur in ocean-floor basalts.

    PubMed

    Sakai, H; Des Marais, D J; Ueda, A; Moore, J G

    1984-01-01

    Fresh submarine basalt glasses from Galapagos Ridge, FAMOUS area, Cayman Trough and Kilauea east rift contain 22 to 160 ppm carbon and 0.3 to 2.8 ppm nitrogen, respectively, as the sums of dissolved species and vesicle-filling gases (CO2 and N2). The large range of variation in carbon content is due to combined effect of depth-dependency of the solubility of carbon in basalt melt and varying extents of vapour loss during magma emplacement as well as in sample crushing. The isotopic ratios of indigenous carbon and nitrogen are in very narrow ranges, -6.2 +/- 0.2% relative to PDB and +0.2 +/- 0.6% relative to atmospheric nitrogen, respectively. In basalt samples from Juan de Fuca Ridge, however, isotopically light carbon (delta 13 C = around -24%) predominates over the indigenous carbon; no indigenous heavy carbon was found. Except for Galapagos Ridge samples, these ocean-floor basalts contain 670 to 1100 ppm sulfur, averaging 810 ppm in the form of both sulfide and sulfate, whereas basalts from Galapagos Ridge are higher in both sulfur (1490 and 1570 ppm) and iron (11.08% total iron as FeO). the delta 34S values average +0.3 +/- 0.5% with average fractionation factor between sulfate and sulfide of +7.4 +/- 1.6%. The sulfate/sulfide ratios tend to increase with increasing water content of basalt, probably because the oxygen fugacity increases with increasing water content in basalt melt.

  15. Determining the geographical origin of Chinese cabbages using multielement composition and strontium isotope ratio analyses

    NASA Astrophysics Data System (ADS)

    BONG, Y.; Shin, W.; Gautam, M. K.; Jeong, Y.; Lee, A.; Jang, C.; Lim, Y.; Chung, G.; Lee, K.

    2012-12-01

    Recently, the Korean market has seen many cases of Chinese cabbage (Brassica rapa ssp. pekinensis) that have been imported from China, yet are sold as a Korean product to illegally benefit from the price difference between the two products. This study aims to establish a method of distinguishing the geographical origin of Chinese cabbage. One hundred Chinese cabbage heads from Korea and 60 cabbage heads from China were subjected to multielement composition and strontium isotope ratio (87Sr/86Sr) analyses. The 87Sr/86Sr ratio differed, based on the geological characteristics of their district of production. In addition, the content of many elements differed between cabbages from Korea and China. In particular, the difference in the content of Sr and Ti alone and the combination of Sr, Ca, and Mg allowed us to distinguish relatively well between Korea and China as the country of origin. The present study demonstrates that the chemical and Sr isotopic analyses exactly reflect the geology of the production areas of Chinese cabbage. Also, multivariate statistical analyses of multiple elements were found to be very effective in distinguishing the geographical origin of Chinese cabbages.

  16. Concentrations and isotope ratios of carbon, nitrogen and sulfur in ocean-floor basalts

    USGS Publications Warehouse

    Sakai, H.; Marais, D.J.D.; Ueda, A.; Moore, J.G.

    1984-01-01

    Fresh submarine basalt glasses from Galapagos Ridge, FAMOUS area, Cayman Trough and Kilauea east rift contain 22 to 160 ppm carbon and 0.3 to 2.8 ppm nitrogen, respectively, as the sums of dissolved species and vesicle-filling gases (CO2 and N2). The large range of variation in carbon content is due to combined effect of depth-dependency of the solubility of carbon in basalt melt and varying extents of vapour loss during magma emplacement as well as in sample crushing. The isotopic ratios of indigenous carbon and nitrogen are in very narrow ranges,-6.2 ?? 0.2% relative to PDB and +0.2 ?? 0.6 %. relative to atmospheric nitrogen, respectively. In basalt samples from Juan de Fuca Ridge, however, isotopically light carbon (??13C = around -24%.) predominates over the indigenous carbon; no indigenous heavy carbon was found. Except for Galapagos Ridge samples, these ocean-floor basalts contain 670 to 1100 ppm sulfur, averaging 810 ppm, in the form of both sulfide and sulfate, whereas basalts from Galapagos Ridge are higher in both sulfur (1490 and 1570 ppm) and iron (11.08% total iron as FeO). The ??34S values average +0.3 ?? 0.5%. with average fractionation factor between sulfate and sulfide of +7.4 ?? 1.6%.. The sulfate/sulfide ratios tend to increase with increasing water content of basalt, probably because the oxygen fugacity increases with increasing water content in basalt melt. ?? 1984.

  17. High-temperature pyrolysis/gas chromatography/isotope ratio mass spectrometry: simultaneous measurement of the stable isotopes of oxygen and carbon in cellulose.

    PubMed

    Woodley, Ewan J; Loader, Neil J; McCarroll, Danny; Young, Giles H F; Robertson, Iain; Heaton, Timothy H E; Gagen, Mary H; Warham, Joseph O

    2012-01-30

    Stable isotope analysis of cellulose is an increasingly important aspect of ecological and palaeoenvironmental research. Since these techniques are very costly, any methodological development which can provide simultaneous measurement of stable carbon and oxygen isotope ratios in cellulose deserves further exploration. A large number (3074) of tree-ring α-cellulose samples are used to compare the stable carbon isotope ratios (δ(13)C) produced by high-temperature (1400°C) pyrolysis/gas chromatography (GC)/isotope ratio mass spectrometry (IRMS) with those produced by combustion GC/IRMS. Although the two data sets are very strongly correlated, the pyrolysis results display reduced variance and are strongly biased towards the mean. The low carbon isotope ratios of tree-ring cellulose during the last century, reflecting anthropogenic disturbance of atmospheric carbon dioxide, are thus overestimated. The likely explanation is that a proportion of the oxygen atoms are bonding with residual carbon in the reaction chamber to form carbon monoxide. The 'pyrolysis adjustment', proposed here, is based on combusting a stratified sub-sample of the pyrolysis results, across the full range of carbon isotope ratios, and using the paired results to define a regression equation that can be used to adjust all the pyrolysis measurements. In this study, subsamples of 30 combustion measurements produced adjusted chronologies statistically indistinguishable from those produced by combusting every sample. This methodology allows simultaneous measurement of the stable isotopes of carbon and oxygen using high-temperature pyrolysis, reducing the amount of sample required and the analytical costs of measuring them separately.

  18. Chitin: 'Forgotten' Source of Nitrogen: From Modern Chitin to Thermally Mature Kerogen: Lessons from Nitrogen Isotope Ratios

    USGS Publications Warehouse

    Schimmelmann, A.; Wintsch, R.P.; Lewan, M.D.; DeNiro, M.J.

    1998-01-01

    Chitinous biomass represents a major pool of organic nitrogen in living biota and is likely to have contributed some of the fossil organic nitrogen in kerogen. We review the nitrogen isotope biogeochemistry of chitin and present preliminary results suggesting interaction between kerogen and ammonium during thermal maturation. Modern arthropod chitin may shift its nitrogen isotope ratio by a few per mil depending on the chemical method of chitin preparation, mostly because N-containing non-amino-sugar components in chemically complex chitin cannot be removed quantitatively. Acid hydrolysis of chemically complex chitin and subsequent ion-chromatographic purification of the "deacetylated chitin-monomer" D-glucosamine (in hydrochloride form) provides a chemically well-defined, pure amino-sugar substrate for reproducible, high-precision determination of ??15N values in chitin. ??15N values of chitin exhibited a variability of about one per mil within an individual's exoskeleton. The nitrogen isotope ratio differed between old and new exoskeletons by up to 4 per mil. A strong dietary influence on the ??15N value of chitin is indicated by the observation of increasing ??15N values of chitin from marine crustaceans with increasing trophic level. Partial biodegradation of exoskeletons does not significantly influence ??15N values of remaining, chemically preserved amino sugar in chitin. Diagenesis and increasing thermal maturity of sedimentary organic matter, including chitin-derived nitrogen-rich moieties, result in humic compounds much different from chitin and may significantly change bulk ??15N values. Hydrous pyrolysis of immature source rocks at 330??C in contact with 15N-enriched NH4Cl, under conditions of artificial oil generation, demonstrates the abiogenic incorporation of inorganic nitrogen into carbon-bound nitrogen in kerogen. Not all organic nitrogen in natural, thermally mature kerogen is therefore necessarily derived from original organic matter, but may

  19. Precise Zn isotopic ratio measurements of human red blood cell and hair samples by multiple collector-ICP-mass spectrometry.

    PubMed

    Ohno, Takeshi; Shinohara, Atsuko; Chiba, Momoko; Hirata, Takafumi

    2005-04-01

    Precise 66Zn/64Zn and 68Zn/64Zn isotopic ratios of biochemical samples have been measured using multiple collector-ICP-mass spectrometry (MC-ICPMS). In order to eliminate the mass spectrometric interferences on Zn isotopes (e.g., 64Ni+ and 136Ba2+), we chemically purified the analyte using an ion chromatographic technique. The resulting precisions of the 66Zn/64Zn and 68Zn/64Zn ratio measurements were 0.05/1000 and 0.10/1000 (2SD), respectively, which were enough to detect the isotopic variation of Zn in nature. Red blood cell (RBC) samples were collected from five volunteers (four males and one female), including a series of 12 RBC samples from one person through monthly-based sampling over a year. These were analyzed to test possible seasonal changes and variations in 66Zn/64Zn and 68Zn/64Zn ratios among the individuals. The 66Zn/64Zn and 68Zn/64Zn ratios for a series of 12 RBC samples collected over a year were 0.43/1000 and 0.83/1000 higher than the values of highly purified Zn metal (JMC Zn), and no seasonal change could be found. The 66Zn/64Zn and 68Zn/64Zn ratios for RBC samples collected from five volunteers did not vary significantly. In order to investigate Zn isotopic heterogeneity in a human body, Zn isotopic ratios of a hair sample collected from one of the volunteers was also analyzed. The 66Zn/64Zn and 68Zn/64Zn ratios for the hair sample were 0.59/1000 and 1.14/1000 lower than the mean value of RBC samples. This result demonstrates that detectable isotopic fractionation occurs in the human body. The data obtained here suggest that the isotopic ratios of trace metals could provide new information about transportation of metal elements in vivo.

  20. Innovations in Mass Spectrometry for Precise and Accurate Isotope Ratio Determination from Very Small Analyte Quantities (Invited)

    NASA Astrophysics Data System (ADS)

    Lloyd, N. S.; Bouman, C.; Horstwood, M. S.; Parrish, R. R.; Schwieters, J. B.

    2010-12-01

    This presentation describes progress in mass spectrometry for analysing very small analyte quantities, illustrated by example applications from nuclear forensics. In this challenging application, precise and accurate (‰) uranium isotope ratios are required from 1 - 2 µm diameter uranium oxide particles, which comprise less than 40 pg of uranium. Traditionally these are analysed using thermal ionisation mass spectrometry (TIMS), and more recently using secondary ionisation mass spectrometry (SIMS). Multicollector inductively-coupled plasma mass spectrometry (MC-ICP-MS) can offer higher productivity compared to these techniques, but is traditionally limited by low efficiency of analyte utilisation (sample through to ion detection). Samples can either be introduced as a solution, or sampled directly from solid using laser ablation. Large multi-isotope ratio datasets can help identify provenance and intended use of anthropogenic uranium and other nuclear materials [1]. The Thermo Scientific NEPTUNE Plus (Bremen, Germany) with ‘Jet Interface’ option offers unparalleled MC-ICP-MS sensitivity. An analyte utilisation of c. 4% has previously been reported for uranium [2]. This high-sensitivity configuration utilises a dry high-capacity (100 m3/h) interface pump, special skimmer and sampler cones and a desolvating nebuliser system. Coupled with new acquisition methodologies, this sensitivity enhancement makes possible the analysis of micro-particles and small sample volumes at higher precision levels than previously achieved. New, high-performance, full-size and compact discrete dynode secondary electron multipliers (SEM) exhibit excellent stability and linearity over a large dynamic range and can be configured to simultaneously measure all of the uranium isotopes. Options for high abundance-sensitivity filters on two ion beams are also available, e.g. for 236U and 234U. Additionally, amplifiers with high ohm (1012 - 1013) feedback resistors have been developed to

  1. What climate information is recorded in stable isotope ratios of wood lignin methoxyl groups?

    NASA Astrophysics Data System (ADS)

    Greule, Markus; Keppler, Frank

    2010-05-01

    The stable isotope composition of the bioelements C, O, H and N in plant organic matter is known to be a very powerful for various environmental impacts. Particularly tree rings are suitable for this analysis because they exhibit a "climate archive" with a yearly or even biannual resolution. One of the most determined wood compounds is cellulose which amongst others is used to reconstruct the temperature due to measurement of stable hydrogen and oxygen isotopes. Therefore cellulose is converted into cellulose nitrate to eliminate the exchangeable hydroxyl hydrogen or equilibration methods are used. However, a general problem associated with the determination of the stable hydrogen values of marker compounds for the study of climate and environmental conditions is the isolation of the pure compound for analysis by isotope ratio mass spectrometry. Exploitation of components of wood as markers, in particular, has been restricted by the very labour intensive and time consuming preparation of samples (e.g. cellulose nitrate). An alternative way to record climate information from tree rings was recently proposed by Keppler et al. (2007) who measured the stable hydrogen values of methoxyl groups in wood. Lignin methoxyl groups are considered to be stable, i.e. the hydrogen atoms of the methoxyl moiety do not exchange with those of plant water during ongoing metabolic reactions in the plant. Thus the initial deuterium content of the methoxyl groups of lignin in woody tissue at formation is retained throughout the lifetime of the tree and in preserved tissue. The methoxyl content of lignin in wood is usually determined by the Zeisel method (Zeisel, 1885) - the reaction between methyl ethers and hydroiodic acid to form methyl iodide. Exploiting this reaction for the measurement of stable hydrogen values of lignin methoxyl groups ensures that during the entire analytical procedure the isotope signal is preserved since no isotopic exchange occurs between the methyl groups and

  2. Strontium isotope ratio variations in plagioclase phenocrysts from the Imnaha basalt

    NASA Astrophysics Data System (ADS)

    Eckberg, A. E.; Wolff, J. A.; Ramos, F. C.; Hart, G. L.

    2006-12-01

    Of all the Columbia River flood basalt formations, the Imnaha Basalt best captures the isotopic signature of the mantle plume source (see abstract by Wolff, Ramos and Patterson). It is of interest, therefore, to understand the extent to which the plume signature is compromised by magma-lithosphere interaction during transport to the surface. Whole rock 87Sr/86Sr ratios of Imnaha lavas span a narrow range of 0.7038 - 0.7042, and convey a false impression of relative isotopic uniformity. Plagioclase phenocrysts analyzed by LA-MC- ICPMS exhibit much greater variations of 0.7038 - 0.7061 for the whole formation as represented by 8 flows that we have studied. Individual plagioclase phenocrysts in the Imnaha lavas typically fall into two Sr isotope ratio populations: 0.7038 - 0.7044, and 0.7045 - 0.7051. The former population, which encompasses the range of 87Sr/86Sr in whole rocks, is more abundant among a subgroup of flows that have long been recognized as more primitive (Hooper et al., 1984), and is dominated by tabular phenocrysts, some of which are zoned with less radiogenic cores and more radiogenic rims. The less radiogenic end of this range is considered to be representative of the mantle source for the Imnaha Basalt. The latter more radiogenic group of plagioclase grains is texturally more diverse, and is more abundant in flows with relatively evolved bulk compositions. Relatively radiogenic Sr (87Sr/86Sr >0.7044) among Columbia River basalts (whole rocks) is characteristic of post-Imnaha formations, including the very voluminous Grande Ronde flows, and is thought to reflect the involvement of lithospheric components derived from crust and/or mantle. Four of the 8 Imnaha flows so far investigated contain both populations of plagioclase. These results are consistent with a model where magmas residing in crustal magma chambers experience interaction with high- 87Sr/86Sr host rock before and/or during crystallization of plagioclase and are recharged by mantle

  3. Oxygen and carbon isotope ratios of hydrothermal minerals from Yellowstone drill cores

    NASA Astrophysics Data System (ADS)

    Sturchio, N. C.; Keith, T. E. C.; Muehlenbachs, K.

    1990-01-01

    Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface ( in situ temperatures ranging from 81 to 199°C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The δ 18O values of the thirty-two analyzed silica samples (quartz, chalcedony, α-cristobalite, and β-cristobalite) range from -7.5 to +2.8‰ . About one third of the silica 7samples have δ 18O values that are consistent with isotopic equilibrium with present thermal waters; most of the other silica samples appear to have precipitated from water enriched in 18O (up to 4.7‰) relative to present thermal water, assuming precipitation at present in situ temperatures. Available data on fluid-inclusion homogenization temperatures in hydrothermal quartz indicate that silica precipitation occurred mostly at temperatures above those measured during drilling and imply that 15O enrichments in water during silica precipitation were generally larger than those estimated from present conditions. Similarly, clay minerals (celadonite and smectite) have δ 18O values higher (by 3.5 to 7.9‰) than equilibrium values under present conditions. In contrast, all eight analyzed calcite samples are close to isotopic equilibrium with present thermal waters. The frequent incidence of apparent 18O enrichment in thermal water from which the hydrothermal minerals precipitated may indicate that a higher proportion of strongly 18O-enriched deep hydrothermal fluid once circulated through shallow portions of the Yellowstone system, or that a recurring transient 18O-enrichment effect occurs at shallow depths and is caused either by sudden decompressional boiling or by isotopic exchange at low water/rock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are consistent with

  4. The Stable Carbon Isotope Ratio Analysis of Atmospheric Non-Methane Hydrocarbons in Los Angeles, California

    NASA Astrophysics Data System (ADS)

    Gotoh, A. A.; Tyler, S. C.; Meinardi, S.; Gervais, K.; Blake, D. R.

    2003-12-01

    Los Angeles type photochemical air pollution is caused by non-methane hydrocarbons (NMHCs) reacting with hydroxyl radicals and nitrous oxides in the presence of light. To create more effective control strategies in reducing such air pollution, it is essential to have both a better understanding of the complex photochemical processes of NMHCs and the sources of these compounds. From the past successful studies of other atmospheric trace gases such as methane and carbon monoxide, we expect that the stable carbon ratio (13C/12C, reported as a δ 13C value) of each of these hydrocarbons will also reflect the δ 13C value of the source material and/or provide formation on chemical loss processes that fractionate C isotopes. We have developed a NMHC preconcentrator system which enables us to measure δ 13C values using a continuous-flow gas chromatography combustion isotope ratio mass spectrometer (cf-GC/C/IRMS). Our system is similar to the successful design pioneered in Rudolph et al. (1997), but is custom designed by our laboratory. Stable carbon isotope measurements of any of the C2-C5 NMHCs in field and/or lab studies are scarce to date. Our system allows us to report on δ 13C measurements of ethane, ethene, ethyne, propane, propene, n-butane, i-butane, 1-butene, n-pentane, i-pentane, and methyl chloride. To see if we can learn the specific sources contributing to the emissions of a given NMHC within a region by comparing isotopic signatures of its potential sources to δ 13C measurements of it within the local air mass, urban air samples were collected in 3 different cities of Los Angeles County, California, USA, during the summer of 2003 and analyzed for the concentrations and δ 13C values of NMHCs. To our knowledge, this is the first δ 13C analysis of ambient NMHCs conducted in the United States. We report the results of the δ 13C analyses and concentration measurements for selected NMHC species from the urban air samples, and their implications for the local

  5. Application of Inductively Coupled Plasma Mass Spectrometry to the determination of uranium isotope ratios in individual particles for nuclear safeguards

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao Zhi; Esaka, Fumitaka; Esaka, Konomi T.; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu; Watanabe, Kazuo

    2007-10-01

    The capability of inductively coupled plasma mass spectrometry (ICP-MS) for the determination of uranium isotope ratios in individual particles was determined. For this purpose, we developed an experimental procedure including single particle transfer with a manipulator, chemical dissolution and isotope ratio analysis, and applied to the analysis of individual uranium particles in certified reference materials (NBL CRM U050 and U350). As the result, the 235U/ 238U isotope ratio for the particle with the diameter between 0.5 and 3.9 μm was successfully determined with the deviation from the certified ratio within 1.8%. The relative standard deviation (R.S.D.) of the 235U/ 238U isotope ratio was within 4.2%. Although the analysis of 234U/ 238U and 236U/ 238U isotope ratios gave the results with inferior precision, the R.S.D. within 20% was possible for the measurement of the particle with the diameter more than 2.1 μm. The developed procedure was successfully applied to the analysis of a simulated environmental sample prepared from a mixture of indoor dust (NIST SRM 2583) and uranium particles (NBL CRM U050, U350 and U950a). From the results, the proposed procedure was found to be an alternative analytical tool for nuclear safeguards.

  6. 13C/12C isotope ratio MS analysis of testosterone, in chemicals and pharmaceutical preparations.

    PubMed

    de la Torre, X; González, J C; Pichini, S; Pascual, J A; Segura, J

    2001-02-01

    The 13C/12C ratio can be used to detect testosterone misuse in sport because (semi)-synthetic testosterone is supposed to have a 13C abundance different from that of endogenous natural human testosterone. In this study, gas chromatography/combustion isotope ratio mass spectrometry (GC/C/IRMS) analysis for the measurement of the delta 13C/1000 value of testosterone from esterified forms of 13 pharmaceutical preparations, six reagent grade chemicals and three bulk materials (raw materials used in pharmaceutical proarations) obtained world-wide was investigated after applying a strong acidic solvolytic procedure. Mean delta 13C/1000 values of non esterified (free) testosterone from chemicals and bulk materials of several testosterone esters were in the range: -25.91/-32.82/1000 while the value obtained for a (semi)-synthetic, reagent grade, free testosterone was -27.36/1000. The delta 13C/1000 results obtained for testosterone from the pharmaceuticals investigated containing testosterone esters were quite homogeneous (mean and S.D. of delta 13C/1000 values of free testosterone: 27.43 +/- 0.76/1000), being the range between -26.18 and -30.04/1000. Values described above were clearly different from those reported by several authors for endogenous natural human testosterone and its main metabolites excreted into the urine in non-consumers of testosterone (delta 13C/1000 range: from -21.3 to -24.4/1000), while they were similar to those of urinary testosterone and metabolites from individuals treated with testosterone esters and testosterone precursors. This finding justifies the fact that administration of these pharmaceutical formulations led to a statistical decrease of carbon isotope ratio of urinary testosterone and its main metabolites in treated subjects.

  7. Anomalous plutonium isotopic ratios in sediments of Lake Qinghai from the Qinghai-Tibetan Plateau, China.

    PubMed

    Wu, Fengchang; Zheng, Jian; Liao, Haiqing; Yamada, Masatoshi; Wan, Guojiang

    2011-11-01

    The vertical profiles of (239+240)Pu and (137)Cs activities and (240)Pu/(239)Pu isotopic ratios are determined for three sediment cores of Lake Qinghai from the Qinghai-Tibetan Plateau, China, and compared with those in sediments of another three lakes (Lakes Bosten, Sugan, and Shuangta), the only existing ones closest to Lop Nor area, China's nuclear weapons test site in the northwestern part of the country. The mean inventory of 47.7 ± 18.7 MBq km(-2) for (239+240)Pu activity in Lake Qinghai is comparable to the average value of global fallout expected at the same latitude, yet the mean inventory of 1112.0 ± 78.0 MBq km(-2) for (137)Cs is slightly lower than that of global fallout. Anomalously low (240)Pu/(239)Pu isotopic ratios (0.038-0.125) were found in the 3-6.5 cm deep sediment layers, indicating the trace Pu input from early nuclear weapons research activities at Atomic City in the lake's watershed during the 1950-60s. Model calculation indicated that the Pu input accounted for approximately 5-16% of the total Pu inventory. The observation of low (240)Pu/(239)Pu ratio in the deep sediment layer provided a new time marker for recent sediment dating in the lake and around the area. The results are of great significance to the further understanding of sources, records, and environmental impacts of global and regional nuclear activities in the environment and provide important chronological information for further studies on the water eutrophication process and climatic change, and reconstruction of pollution history of organic contaminants and heavy metals in the watershed of Lake Qinghai.

  8. Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability

    SciTech Connect

    Isselhardt, Brett H.

    2011-09-01

    Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of 235U/238U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

  9. Hydrogen and carbon isotopic ratios of polycyclic aromatic compounds in two CM2 carbonaceous chondrites and implications for prebiotic organic synthesis

    NASA Astrophysics Data System (ADS)

    Huang, Yongsong; Aponte, José C.; Zhao, Jiaju; Tarozo, Rafael; Hallmann, Christian

    2015-09-01

    Study of meteoritic organic compounds offers a unique opportunity to understand the origins of the organic matter in the early Solar System. Meteoritic polycyclic aromatic hydrocarbons (PAHs) and heteropolycyclic aromatic compounds (HACs) have been studied for over fifty years, however; their hydrogen stable isotopic ratios (δD) have never been reported. Compound-specific δD measurements of PAHs and HACs are important, in part because the carbon isotopic ratios (δ13C) of various meteoritic PAHs cannot be readily distinguished from their terrestrial counterparts and it is difficult to rule out terrestrial contamination based on carbon isotopic ratios alone. In this study, we have extracted and identified more than sixty PAHs and HACs present in two CM2 carbonaceous chondrites Murchison and LON 94101. Their carbon and hydrogen stable isotopic ratios (δ13C and δD) were measured and used to discuss about their synthetic environments and formation mechanisms. The concentration of aromatic compounds is ∼30% higher in Murchison than in the Antarctic meteorite LON 94101, but both samples contained similar suites of PAHs and HACs. All PAHs and HACs found exhibited positive δD values (up to 1100‰) consistent with an extraterrestrial origin, indicating the relatively low δ13C values are indeed an inherent feature of the meteoritic aromatic compounds. The hydrogen isotopic data suggest aromatic compounds in carbonaceous chondrites were mainly formed in the cold interstellar environments. Molecular level variations in hydrogen and carbon isotopic values offer new insights to the formation pathways for the aromatic compounds in carbonaceous chondrites.

  10. Microanalyses of O isotopes and elemental ratios of reef building coral (Montastrea annularis) by ion microprobe

    NASA Astrophysics Data System (ADS)

    Gabitov, R. I.; Carricart Ganivet, J. P.; Prieto, R. I.

    2012-12-01

    Our understanding of climate change and oceanographic variability through time is largely derived from knowledge of oxygen isotopes (δ18O) and elemental ratios (X/Ca) signatures in coral reefs. However, the existence of inconsistencies in isotopic composition between different coral specimens suggests that factors other than temperature and seawater composition affect isotopic and chemical records. We conducted in situ Secondary Ion Mass Spectrometry (SIMS) analyses on the reef building coral (Montastraea annularis) from Veracuz Reef in the southern Gulf of Mexico. Coral specimen was sliced in perpendicular and parallel directions of its growth. Therefore, one of the sections exposed simultaneously grown skeletal material; another section represents a time series of continuously extended skeleton. The complex microstructure of the coral yields a few morphologically different zones (architectural elements). There are theca-wall (Th), septa (S), costa (C), exothecal (ExD) and endothecal dissepiments (EnD). Dissepiments formation in Montastraea annularis is linked to moon cycles and there are 12 or 13 ExD formed per year; meanwhile, there are 24 or 26 EnD per year (Dávalos-Dehullu et al. 2008). SIMS analyses were performed on Th, S, C, ExD, and EnD at lateral spatial resolution of ~20 μm. SIMS spot profiles with 100 and 500 μm steps were conducted on Th wall in the direction of coral growth. SIMS analyses demontrate that δ18O in Th, S, C, and ExD that grown at the same time are similar to each other within 1 sigma error. However, δ18O in EnD is isotopically heavier by 1 ‰ than those of simultaneously grown T,S, and ExD. The reverse dependence of δ18O on growth rate of corals and inorganically precipitated aragonite was reported by previous works and potentially could explain the δ18O enrichment in EnD, which grow by 35% slower than ExD (McConnaughey 1989; Dávalos-Dehullu et al. 2008; Gabitov 2012). SIMS spot profiles in the coral growth direction yielded

  11. Nitrogen Isotopic Ratios in Cometary NH2: Implication for 15N-fractionation in Ammonia

    NASA Astrophysics Data System (ADS)

    Shinnaka, Yoshiharu; Kawakita, Hideyo; Jehin, Emmanuël; Decock, Alice; Hutsemékers, Damien; Manfroid, Jean; Arai, Akira

    2015-11-01

    Isotopic ratios in cometary molecules are diagnostic for the physico-chemical conditions where molecules formed and are processed, from the interstellar medium to the solar nebula. Usually temperatures at the molecular formation control the fractionation of the heavier element in molecular species, e.g., D-fractionation in water.In cometary volatiles, the 14N/15N ratios in CN have been well observed (Manfroid et al. 2009, A&A, 503, 613, and reference therein) and is consistent with the ratio in HCN (a most probable parent of CN) measured in few comets (Bockelée-Morvan et al. 2008, ApJ, 679, L49). Those ratios are enriched compared to the proto-solar value by a factor of ~3. In contrast to those Nitriles, there are only few reports on 14N/15N ratios in Ammonia (as Amine) (Rousselot et al. 2014, ApJ, 780, L17; Shinnaka et al. 2014, ApJ, 782, L16). Ammonia (NH3) is usually the most abundant and HCN is the second most abundant N-bearing volatiles in cometary ice. Especially, recent observations of 15NH2 revealed the 14N/15N ratios in NH3 are comparable to those of CN. However, from the viewpoint of theoretical work, the enrichment of 15N in cometary NH3 cannot be reproduced by current chemical network models. Information about the diversity of the 14N/15N ratios in NH3 of individual comets is needed to understand the formation mechanisms/environments of NH3 in the early solar system.To clarify the diversity of the 14N/15N ratios in cometary NH3, we determine the 14N/15N ratios in NH3 for more than ten comets individually which include not only Oort cloud comets but also short period comets by using the high-resolution optical spectra of NH2. These spectra were obtained with both the UVES mounted on the VLT in Chile and the HDS on the Subaru Telescope in Hawaii.The derived 14N/15N ratios in NH3 for more than ten comets show high 15N-enrichment compared with the elemental abundances of nitrogen in the Sun by about factor of ~3 and has no large diversity depending on

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

    SciTech Connect

    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.

  13. Measurement of Ground Level Muon Charge Ratio Using ECRS Simulation

    NASA Astrophysics Data System (ADS)

    Sanjeewa, Hakmana; He, Xiaochun; Cleven, Christopher

    2006-11-01

    The Muon charge ratio at the Earth's surface has been studied with a Geant4 based simulation for two different geomagnetic locations: Atlanta and Lynn Lake. The simulation results are shown in excellent agreement with the data from NMSU-WIZARD/CAPRICE and BESS experiments at Lynn Lake, At low momentum, ground level muon charge ratios show latitude dependent geomagnetic effects for both Atlanta and Lynn Lake from the simulation. The simulated charge ratio is 1.20 ± 0.05 (without geomagnetic field), 1.12 ± 0.05 (with geomagnetic field) for Atlanta and 1.22 ± 0.04 (with geomagnetic field) for Lynn Lake. These types of studies are very important for analyzing secondary cosmic ray muon flux distribution at Earth's surface and can be used to evaluate the parameter of atmospheric neutrino oscillations.

  14. Heavy with child? Pregnancy status and stable isotope ratios as determined from biopsies of humpback whales

    PubMed Central

    Clark, Casey T.; Fleming, Alyson H.; Calambokidis, John; Kellar, Nicholas M.; Allen, Camryn D.; Catelani, Krista N.; Robbins, Michelle; Beaulieu, Nicole E.; Steel, Debbie; Harvey, James T.

    2016-01-01

    Understanding reproductive rates of wild animal populations is crucially important for management and conservation. Assessing pregnancy status of free-ranging cetaceans has historically been difficult; however, recent advances in analytical techniques have allowed the diagnosis of pregnancy from small samples of blubber tissue. The primary objectives of this study were as follows: (i) to test the efficacy of blubber progesterone assays as a tool for diagnosing pregnancy in humpback whales (Megaptera novaeangliae); (ii) to estimate the pregnancy rate of humpback whales in Monterey Bay, California; and (iii) to investigate the relationship between stable isotopes and reproductive status of these whales. Progesterone concentrations of female whales fell into two distinct groups, allowing for diagnostic separation of pregnant and non-pregnant individuals. Pregnancy rate varied between years of the study (48.4%% in 2011 and 18.5% in 2012), but fell within the range of other estimates of reproductive success for this population. Stable carbon and nitrogen isotope ratios were examined to investigate the impacts of pregnancy on these values. Neither δ15N nor δ13C varied in a consistent way among animals of different sex or reproductive status. The relationship between δ15N and δ13C was strongly positive for male and non-pregnant female humpbacks; however, no relationship existed for pregnant whales. This difference may be indicative of the effects of pregnancy on δ15N, resulting from tissue synthesis and reduced excretion of nitrogenous waste, as well as on δ13C through increased mobilization of lipid stores to meet the energetic demands of pregnancy. Ultimately, our results support the use of blubber progesterone assays for diagnosing pregnancy in humpback whales and indicate that, when paired with other approaches (e.g. stable isotope analysis), pregnancy status can be an informative tool for addressing questions about animal physiology, ecology and population

  15. Tracing the geographical origin of early potato tubers using stable hydrogen isotope ratios of methoxyl groups.

    PubMed

    Keppler, Frank; Hamilton, John T G

    2008-12-01

    The application of stable isotope ratio measurements has become an extremely useful tool for tracing the provenance of food products, thus ensuring that consumers receive products which comply with their labelled specifications. Recently, it has been shown that relative stable hydrogen isotope abundances (delta(2)H values) of wood lignin methoxyl groups have a distinct range that reflects the delta(2)H values of their meteoric source water. Furthermore, it has been suggested that the isotope information stored in methoxyl groups in plant matter generally might assist with determining the place of origin of plant material. We now have measured delta(2)H values of methoxyl groups from natural compounds in tubers of early potatoes (Solanum tuberosum) grown in different geographical locations. Tubers of early potatoes were collected from across Europe and regions close to the Mediterranean Sea between April and July 2004. The methoxyl groups from the potatoes were found to be highly depleted in (2)H, relative to both their meteoric water and bulk biomass, and a systematic shift of the delta(2)H values between methoxyl groups and meteoric water was observed. A constant fractionation of-161+/-11 per thousand. between methoxyl groups and modelled meteoric water is shown over a transaction covering the delta(2)H values of meteoric water from-95 per thousand in Northern Sweden to+25 per thousand in Egypt. From this information, early potato tubers from Middle Europe can be clearly distinguished from those of Mediterranean regions and from Northern Europe. Thus, we suggest that delta(2)H values of methoxyl groups have the potential to become an effective tool in assisting with the constraint of the geographical origin of potato tubers and other food stuffs.

  16. Detecting animal by-product intake using stable isotope ratio mass spectrometry (IRMS).

    PubMed

    da Silva, D A F; Biscola, N P; Dos Santos, L D; Sartori, M M P; Denadai, J C; da Silva, E T; Ducatti, C; Bicudo, S D; Barraviera, B; Ferreira, R S

    2016-11-01

    Sheep are used in many countries as food and for manufacturing bioproducts. However, when these animals consume animal by-products (ABP), which is widely prohibited, there is a risk of transmitting scrapie - a fatal prion disease in human beings. Therefore, it is essential to develop sensitive methods to detect previous ABP intake to select safe animals for producing biopharmaceuticals. We used stable isotope ratio mass spectrometry (IRMS) for (13)C and (15)N to trace animal proteins in the serum of three groups of sheep: 1 - received only vegetable protein (VP) for 89 days; 2 - received animal and vegetable protein (AVP); and 3 - received animal and vegetable protein with animal protein subsequently removed (AVPR). Groups 2 and 3 received diets with 30% bovine meat and bone meal (MBM) added to a vegetable diet (from days 16-89 in the AVP group and until day 49 in the AVPR group, when MBM was removed). The AVPR group showed (15)N equilibrium 5 days after MBM removal (54th day). Conversely, (15)N equilibrium in the AVP group occurred 22 days later (76th day). The half-life differed between these groups by 3.55 days. In the AVPR group, (15)N elimination required 53 days, which was similar to this isotope's incorporation time. Turnover was determined based on natural (15)N signatures. IRMS followed by turnover calculations was used to evaluate the time period for the incorporation and elimination of animal protein in sheep serum. The δ(13)C and δ(15)N values were used to track animal protein in the diet. This method is biologically and economically relevant for the veterinary field because it can track protein over time or make a point assessment of animal feed with high sensitivity and resolution, providing a low-cost analysis coupled with fast detection. Isotopic profiles could be measured throughout the experimental period, demonstrating the potential to use the method for traceability and certification assessments.

  17. Pedogenic Formation of Perylene in a Terrestrial Soil Profile: Evidence From Carbon Isotopic Ratios

    NASA Astrophysics Data System (ADS)

    Gocht, T.; Jochmann, M. A.; Blessing, M.; Barth, J.; Schmidt, T. C.; Grathwohl, P.

    2005-12-01

    Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants (POP), which are introduced into the environment mainly due to combustion of fossil fuel. Perylene is one compound of the PAHs that consists of 5 condensed rings like the well known carcinogenic benzo(a)pyrene. Apart from the pyrogenic formation, there are strong indications that it is produced biologically and/or diagenetically under anaerobic conditions. This conclusion was derived from the presence of perylene in deeper parts of marine and lacustrine sediment profiles, where the combustion-derived PAHs are almost absent ( Lima et al., 2003). 13C/12C compound-specific stable isotopic ratios were successfully applied for the differentiation of probably biologically generated perylene in tropical termite nests and pyrolytic perylene from surface soils of temperate regions ( Wilcke et al., 2002). Our study is the first aiming on the determination of the different processes of perylene formation at one location using carbon isotopic ratios such as 13C/12C. We determined PAHs in natural soils of southern Germany. At one location in the Black Forest we found for the first time evidence for natural perylene production in the subsoil of terrestrial environments. Apart from the combustion derived PAHs that accumulate at the top of all soil profiles, the depth distribution of perylene shows the highest peak in the subsoil about 1 m below the surface. Due to its very low solubility (0.4 μg l-1 at 25 °C) vertical transport of perylene with seepage water is very unlikely. Thus, we suggest atmospheric deposition of pyrogenic perylene at the top of the profile and in-situ generation in the subsoil, probably due to microbial activities. In order to distinguish between the pyrogenic and natural generation we employed 13C/12C compound-specific stable isotope analysis of perylene in soil samples from the top of the profile as well as from the subsoil. Preliminary measurements with soil extracts show strong

  18. Hydrogen Isotope Ratios of Leaf Waxes in C3 and C4 Grasses Record Meteoric Water and Aridity Signatures

    NASA Astrophysics Data System (ADS)

    Smith, F. A.; Freeman, K. H.; Ehleringer, J. R.; Helliker, B.

    2004-12-01

    Hydrogen isotope ratios of sedimentary n-alkanes (C27-C33) from vascular plants potentially provide a valuable record of past hydrologic conditions. To explore this, we analyzed grasses grown in a greenhouse and calculated fractionation factors (epsilon) between source water and n-alkane for each sample. An average difference of 21 permil is observed between C3 and C4 grasses, which is comparable to that determined for grasses collected from the Great Plains. The more positive isotope values in C4 grasses likely reflects smaller interveinal distance compared to C3 grass leaves, allowing greater back-diffusion of transpirationally enriched water from stomata, as documented with the oxygen isotope ratios of grass leaf water and cellulose by Helliker and Ehleringer (2000). The oxygen isotope difference is magnified at low relative humidity, when transpiration rates are higher. A similar effect is expected in hydrogen isotope ratios of leaf water and plant compounds. However, preliminary results from grasses grown hydroponically at different relative humidities suggest that there may be a decoupling of the hydrogen isotope ratio of leaf-wax n-alkanes and the oxygen isotope ratio of leaf water and cellulose. To examine the effects of source water delta D and climate on n-alkane delta D values, we analyzed grasses collected from the Great Plains. We use river water delta D values as a proxy for source water and the epsilon values determined in the greenhouse experiments, to predict expected values for C3 and C4 grass lipids. Measured values compare well to predicted values, with the exception of two semi-arid sites where evapotranspiration may have led to leaf-waters that are enriched in deuterium. Residual delta D values (measured-expected) correspond strongly with measures of aridity, such as annual precipitation and recipitation/evaporation ratios.

  19. An instrumental and numerical method to determine the hydrogenic ratio in isotopic experiments in the TJ-II stellarator

    SciTech Connect

    Baciero, A. Zurro, B.; Martínez, M.

    2014-11-15

    The isotope effect is an important topic that is relevant for future D-T fusion reactors, where the use of deuterium, rather than hydrogen, may lean to improved plasma confinement. An evaluation of the ratio of hydrogen/deuterium is needed for isotope effect studies in current isotopic experiments. Here, the spectral range around H{sub α} and D{sub α} lines, obtained with an intensified multi-channel detector mounted to a 1-m focal length spectrometer, is analyzed using a fit function that includes several Gaussian components. The isotopic ratio evolution for a single operational day of the TJ-II stellarator is presented. The role of injected hydrogen by Neutral Beam Injection heating is also studied.

  20. Stable hydrogen-isotope ratios in beetle chitin: preliminary European data and re-interpretation of North American data

    NASA Astrophysics Data System (ADS)

    Gröcke, Darren R.; Schimmelmann, Arndt; Elias, Scott; Miller, Randall F.

    2006-08-01

    Beetle exoskeletons contain chitin, a poly amino-sugar that is biosynthesized incorporating hydrogen isotopes from diet and water. As the stable isotope ratios D/H (or 2H/ 1H, expressed as δ D values) of precipitation and diet are jointly influenced by climate, the biochemically recorded hydrogen-isotope ratio in fossil beetle exoskeleton has the potential to be used for paleoclimatic reconstruction. New δ D data from modern beetles are presented as a preliminary database for Europe, with a re-evaluation of earlier North American data. We present correlated matrices of δ D values in modern beetle chitin and modern precipitation to demonstrate the concept. We review the pertinent literature to highlight the history, utility, and likely future research directions for the use of chitin's stable isotopes in entomological paleoclimatology.

  1. Stable isotope physiology of stem succulents across a broad range of volume-to-surface area ratio.

    PubMed

    Hultine, Kevin R; Williams, David G; Dettman, David L; Butterfield, Bradley J; Puente-Martinez, Raul

    2016-11-01

    Volume-to-surface area ratio (V:S) across stem succulent taxa varies by almost two orders of magnitude. The broad range in V:S of cacti and other succulent species likely has considerable importance for adaptation since stem volume determines the storage capacity of water, carbon and nutrients and stem surface area is directly related to whole-stem photosynthetic capacity. We examined the intrinsic physiological tradeoffs across diverse stem morphologies in three divergent evolutionary groups where stem succulence is common: Cactoideae, Opuntioideae (Cactaceae) and Euphorbiaceae. We predicted that variation in physiological response to environmental conditions would be (1) constrained by stem V:S, and (2) detectable in the stable isotope ratios of plant tissues. Stable isotope ratios were measured in the spines/prickles of 62 stem-succulent species occurring in a common garden setting in Phoenix, AZ, USA. Biomass δ(13)C, δ(2)H and δ(18)O increased with V:S in Cactoideae only, possibly reflecting various levels of Crassulacean acid metabolism (CAM) strength in the other lineages. Within Cactoideae-group with the highest CAM strength and largest range in V:S-δ(13)C and δ(18)O increased 2.2 and 11.5 ‰, respectively, with a 22-fold increase in V:S. Both δ(13)C and V:S decreased with species climate-niche estimates of precipitation, indicating that stem morphology and physiology in Cactoideae may be constrained by available moisture. Taken together, these data suggest that physiological tradeoffs associated with stem V:S are detectable across broad evolutionary groups despite differences in CAM strength.

  2. Forest Canopy Respiration Determined by Real Time Fourier Transform Spectroscopy of CO2 Isotope Ratios

    NASA Astrophysics Data System (ADS)

    Montecastro, D.; Mount, G. H.; Lamb, B.; Westberg, H.

    2002-12-01

    Exchange of gases between the biosphere and the atmosphere is a major pathway in many biogeochemical cycles. Biosphere/atmosphere exchange of CO2 is a focal point for understanding feedback mechanisms. We have developed a tower-based disjunct eddy covariance sampling system coupled to a low resolution [~1 cm-1] Fourier Transform infrared spectrometer to determine forest canopy respiration. The instrument measures the stable carbon isotope ratio of CO2 (13:12) in near real time in the spectral range 2250-2550 cm-1. Measurement shows ~0.2 δ13C precision when tested with a carbon isotope standard. The disjunct system operates on 1-minute time centers. The gas sample is collected in a temperature-controlled 1-meter path length cell at ambient pressure. This new instrument will be field tested this summer at the University of Michigan PROPHET site as part of the Biocomplexity project in collaboration with measurements by groups from NCAR, Purdue University, and UMBS.

  3. Stable Carbon Isotope Ratios and Biodegradation Rates of BTEX Compounds at the Tranguch Gasoline Site, Hazelton, Pennsylvania

    DTIC Science & Technology

    2005-03-03

    Absence of Stable Carbon Isotope Fractionation of Satu- rated and Polycyclic Aromatic Hydrocarbons During Aerobic Bacterial Biodegradation ,” Org... biodegradation ; measure the overall metabolic activity and state of the on-site bacterial consortia; and determine fuel hydrocarbon stable isotope ratios...Hazleton, Pennsylvania. The goal of this study was to determine the rates and efficacy of on-site bacterial fuel hydrocarbon biodegradation ; measure

  4. Assessment of Non-traditional Isotopic Ratios by Mass Spectrometry for Analysis of Nuclear Activities. Annual Report 2011

    SciTech Connect

    Biegalski, Steven R.; Buchholz, Bruce A.

    2011-08-24

    The objective of this work is to identify isotopic ratios suitable for analysis via mass spectrometry that distinguish between commercial nuclear reactor fuel cycles, fuel cycles for weapons grade plutonium, and products from nuclear weapons explosions. Methods will also be determined to distinguish the above from medical and industrial radionuclide sources. Mass spectrometry systems will be identified that are suitable for field measurement of such isotopes in an expedient manner.

  5. Quantitation and Ratio Determination of Uranium Isotopes in Water and Soil Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

    DTIC Science & Technology

    2012-03-01

    time 10UNCLASSIFIEDD Kurk, 2012 EMDQ, La Jolla CA α Spectroscopy  Measures 235 and 238 isotope ions 235 from the Actinium Decay Series U235→ Th231...Measures 235 and 238 isotope ions 235 from the Actinium Decay Series U235→ Th231 → Pa231 → Ac227 → …..  Sample preparation Count ions Conc. and Ratio: two

  6. Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania

    SciTech Connect

    Magdas, D. A. Cristea, G. Bot, A.; Puscas, R.; Radu, S.; Mirel, V.; Cordea, D. V.; Mihaiu, M.

    2013-11-13

    Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ{sup 18}O and δ{sup 2}H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ{sup 18}O and δ{sup 2}H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

  7. Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania

    NASA Astrophysics Data System (ADS)

    Magdas, D. A.; Cristea, G.; Cordea, D. V.; Bot, A.; Puscas, R.; Radu, S.; Mirel, V.; Mihaiu, M.

    2013-11-01

    Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ18O and δ2H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ18O and δ2H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

  8. Climate controls on forest soil C isotope ratios in the Southern Appalachian Mountains

    SciTech Connect

    Garten, C.T. Jr.; Cooper, L.W.; Post, W.M. III; Hanson, P.J.

    2000-04-01

    A large portion of terrestrial carbon (C) resides in soil organic carbon (SOC). The dynamics of this large reservoir depend on many factors, including climate. Measurements of {sup 13}C:{sup 12}C ratios, C concentrations, and C:N ratios at six forest sites in the Southern Appalachian Mountains (USA) were used to explore several hypotheses concerning the relative importance of factors that control soil organic matter (SOM) decomposition and SOC turnover. Mean {delta}{sup 13}C values increased with soil depth and decreasing C concentrations along a continuum from fresh litter inputs to more decomposed soil constituents. Data from the six forest sites, in combination with data from a literature review, indicate that the extent of change in {delta}{sup 13}C values from forest litter inputs to mineral soil is significantly associated with mean annual temperature. The findings support a conceptual model of vertical changes in forest soil {delta}{sup 13}C values, C concentrations, and C:N ratios that are interrelated through climate controls on decomposition. The authors hypothesize that, if other environmental factors are not limiting, then temperature and litter quality indirectly control the extent of isotopic fractionation during SOM decomposition in temperate forest ecosystems.

  9. Climate controls on forest soil C isotope ratios in the southern Appalachian Mountains

    SciTech Connect

    Garten Jr, Charles T; Cooper, Lee W; Post, Wilfred M; Hanson, Paul J

    2000-04-01

    A large portion of terrestrial carbon (C) resides in soil organic carbon (SOC). The dynamics of this large reservoir depend on many factors, including climate. Measurements of {sup 13}C:{sup 12}C ratios, C concentrations, and C:N ratios at six forest sites in the Southern Appalachian Mountains (USA) were used to explore several hypotheses concerning the relative importance of factors that control soil organic matter (SOM) decomposition and SOC turnover. Mean {delta}{sup 13}C values increased with soil depth and decreasing C concentrations along a continuum from fresh litter inputs to more decomposed soil constituents. Data from the six forest sites, in combination with data from a literature review, indicate that the extent of change in {delta}{sup 13}C values from forest litter inputs to mineral soil (20 cm deep) is significantly associated with mean annual temperature. The findings support a conceptual model of vertical changes in forest soil {delta}{sup 13}C values, C concentrations, and C:N ratios that are interrelated through climate controls on decomposition. We hypothesize that, if other environmental factors (like soil moisture) are not limiting, then temperature and litter quality indirectly control the extent of isotopic fractionation during SOM decomposition in temperate forest ecosystems.

  10. Oxygen isotope ratios in trees reflect mean annual temperature and humidity.

    PubMed

    Burk, R L; Stuiver, M

    1981-03-27

    Values of the oxygen isotope ratios (delta(18)O) in tree-ring cellulose closely reflect the delta(18)O values in atmospheric precipitation and hence mean annual temperature. The change in delta(18)O in cellulose is 0.41 per mil per degree Celsius for selected near-coastal stations. The values of delta(18)O in precipitation and cellulose also change with altitude, as demonstrated for Mount Rainier, Washington. A temperature lapse rate of 5.2 degrees +/- 0.5 degrees C per 1000 meters calculated from cellulose delta(18)O values agrees with the accepted mean annual lapse rate of 5 degrees C per 1000 meters for this region. Cellulose delta(18)O values and delta(18)O values of carbon dioxide equilibrated with leaf water differ by a fixed 16 per mil.

  11. Oxygen isotope ratios in trees reflect mean annual temperature and humidity

    SciTech Connect

    Burk, R.L.; Stuiver, M.

    1981-03-27

    Values of the oxygen isotope ratios (delta/sup 18/O) in tree-ring cellulose closely reflect the delta/sup 18/O values in atmospheric precipitation and hence mean annual temperature. The change in delta/sup 18/O in cellulose is 0.41 per mil per degree Celsius for selected near-coastal stations. The values of delta/sup 18/O in precipitation and cellulose also change with altitude, as demonstrated for Mount Rainier, Washington. A temperature lapse rate of 5.2/sup 0/ +/- 0.5/sup 0/C per 1000 meters calculated from cellulose delta/sup 18/O values agrees with the accepted mean annual lapse rate of 5/sup 0/C per 1000 meters for this region. Cellulose delta/sup 18/O values and delta/sup 18/O values of carbon dioxide equilibrated with leaf water differ by a fixed 16 per mil.

  12. Oxygen isotope ratios in trees reflect mean annual temperature and humidity

    SciTech Connect

    Burk, R.L.; Stuiver, M.

    1981-03-27

    Values of the oxygen isotope ratios (delta/sup 18/O) in tree-ring cellulose closely reflect the delta/sup 18/O values in atmospheric precipitation and hence mean annual temperature. The change in delta/sup 18/O in cellulose is 0.41 per mil per degree Celsius for selected near-coastal stations. The values of delta/sup 18/O in precipitation and cellulose also change with altitude, as demonstrated for Mount Rainier, Washington. A temperature lapse rate of 5.2/sup 0/ per 1000 meters calculated from cellulose delta/sup 18/O values agrees with the accepted mean annual lapse rate of 5/sup 0/C per 1000 meters for this region.

  13. Development and Deployment of Retrofit PolarisQ Ion Trap Mass Spectrometer for Isotope Ratio Measurements

    SciTech Connect

    Thompson, Cyril V.; Whitten, William B.

    2015-11-01

    This report describes Oak Ridge National Laboratory’s (ORNL) FY15 progress in support of National Nuclear Security Administration’s (NNSA) Portable Mass Spectrometer project. A retrofit PolarisQ ion trap mass spectrometer (RPMS) has been assembled from components of two PolarisQ ion trap mass spectrometers used in previous isotope ratio programs. The retrofit mass spectrometer includes a custom Hastelloy vacuum chamber which is about ¼ the size of the standard aluminum vacuum chamber and reduces the instrument weight from the original by nine pounds. In addition, the new vacuum chamber can be independently heated to reduce impurities such as water, which reacts with UF6 to produce HF in the vacuum chamber. The analyzer and all components requiring service are mounted on the chamber lid, facilitating quick and easy replacement of consumable components such as the filament and electron multiplier.

  14. Complementary stable carbon isotope ratio and amount of substance measurements in sports anti-doping.

    PubMed

    Cawley, Adam T; George, Adrian V

    2012-12-01

    The detection of steroids originating from synthetic precursors against a background of their chemically identical natural analogues has proven to be a significant challenge for doping control laboratories accredited by the World Anti-Doping Agency (WADA). The complementary application of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) has been demonstrated to provide specific detection of endogenous steroid misuse for improved anti-doping analysis. Markers of synthetically derived steroids are reviewed on the basis of abnormal urinary excretions and low (13)C content. A combinatorial approach is presented for the interpretation of GC-MS and GC-C-IRMS data in the anti-doping context. This methodology can allow all relevant information concerning an individual's metabolism to be assessed in order to make an informed decision with respect to a doping violation.

  15. Selected isotope ratio measurements of light metallic elements (Li, Mg, Ca, and Cu) by multiple collector ICP-MS

    PubMed Central

    Platzner, Thomas I.; Segal, Irina

    2007-01-01

    The unique capabilities of multiple collector inductively coupled mass spectrometry (MC-ICP-MS) for high precision isotope ratio measurements in light elements as Li, Mg, Ca, and Cu are reviewed in this paper. These elements have been intensively studied at the Geological Survey of Israel (GSI) and other laboratories over the past few years, and the methods used to obtain high precision isotope analyses are discussed in detail. The scientific study of isotopic fractionation of these elements is significant for achieving a better understanding of geochemical and biochemical processes in nature and the environment. PMID:17962922

  16. Carbon isotope ratio mass spectrometry for detection of endogenous steroid use: a testing strategy.

    PubMed

    Ahrens, Brian D; Butch, Anthony W

    2013-07-01

    Isotope ratio mass spectrometry (IRMS) testing is performed to determine if an atypical steroid profile is due to administration of an endogenous steroid. Androsterone (Andro) and etiocholanolone (Etio), and/or the androstanediols (5α- and 5β-androstane-3α,17β-diol) are typically analyzed by IRMS to determine the (13) C/(12) C ratio. The ratios of these target compounds are compared to the (13) C/(12) C ratio of an endogenous reference compound (ERC) such as 5β-pregnane-3α,20α-diol (Pdiol). Concentrations of Andro and Etio are high so (13) C/(12) C ratios can easily be measured in most urine samples. Despite the potentially improved sensitivity of the androstanediols for detecting the use of some testosterone formulations, additional processing steps are often required that increase labour costs and turnaround times. Since this can be problematic when performing large numbers of IRMS measurements, we established thresholds for Andro and Etio that can be used to determine the need for additional androstanediol testing. Using these criteria, 105 out of 2639 urine samples exceeded the Andro and/or Etio thresholds, with 52 of these samples being positive based on Andro and Etio IRMS testing alone. The remaining 53 urine samples had androstanediol IRMS testing performed and 3 samples were positive based on the androstanediol results. A similar strategy was used to establish a threshold for Pdiol to identify athletes with relatively (13) C-depleted values so that an alternative ERC can be used to confirm or establish a true endogenous reference value. Adoption of a similar strategy by other laboratories can significantly reduce IRMS sample processing and analysis times, thereby increasing testing capacity.

  17. Long-term stability of hydrogen isotope ratios in hydrated volcanic glass

    NASA Astrophysics Data System (ADS)

    Cassel, Elizabeth J.; Breecker, Daniel O.

    2017-03-01

    The advancement of conceptual and numerical geodynamic models necessitates quantitative, orogen-scale paleoelevation data. Felsic volcanic glasses, which record the hydrogen isotope compositions (δD) of meteoric water shortly after deposition, provide several advantages as a paleoelevation proxy. Questions remain, however, about the reliability of this relatively new proxy, including the effect of hydrofluoric (HF) acid abrasion in the preparation of glass shards for hydrogen isotope analysis and the stability of hydrogen isotope ratios in hydrated glass shards over geologic time (106-107 years). HF acid abrasion of natural ancient glass shards results in systematic shifts in glass δD values away from modern water δD values. To evaluate the effectiveness of HF acid abrasion, we treated 70-150 μm glass shards separated from various natural tephras with deuterium-labeled water (DLW; δD = +18,205‰) for up to 400 days. For all glasses, this treatment resulted in elevated δD values in comparison to untreated samples. HF acid abrasion after DLW exposure, however, removed this effect and restored glass shards to their original untreated δD values in samples older than 104 years. HF acid abrasion removes hydrous alteration precipitates at the glass surface without measurably changing the δD values of the underlying hydrated glass, regardless of abrasion duration or glass composition. Additionally, 45-34 Ma glasses record δD values that directly reflect their depositional environments as determined by stratigraphy: glasses from tuffs deposited in demonstrably evaporative lacustrine environments have relatively high δD values compared to glasses from contemporaneous tuffs deposited in nearby fluvial environments, which have much lower δD values. The preservation of δD values that systematically vary with original depositional environment, despite >30 Myr of post-hydration exposure to the same meteoric water, indicates that these volcanic glasses resisted

  18. Influences of β-HCG administration on carbon isotope ratios of endogenous urinary steroids.

    PubMed

    Piper, Thomas; Baume, Norbert; Strahm, Emanuel; Emery, Caroline; Saugy, Martial

    2012-05-01

    Several factors influencing the carbon isotope ratios (CIR) of endogenous urinary steroids have been identified in recent years. One of these should be the metabolism of steroids inside the body involving numerous different enzymes. A detailed look at this metabolism taking into account differences found between steroids excreted as glucuronides or as sulphates and hydrogen isotope ratios of different steroids pointed out possibility of unequal CIR at the main production sites inside the male body - the testes and the adrenal glands. By administration of β-HCG it is possible to strongly stimulate the steroid production within the testes without influencing the production at the adrenal glands. Therefore, this treatment should result in changed CIR of urinary androgens in contrast to the undisturbed pre-treatment values. Four male volunteers received three injections of β-HCG over a time course of 5 days and collected their urine samples at defined intervals after the last administration. Those samples showing the largest response in contrast to the pre-administration urines were identified by steroid profile measurements and subsequent analysed by GC/C/IRMS. CIR of androsterone, etiocholanolone, testosterone, 5α- and 5β-androstanediol and pregnanediol were compared. While pregnanediol was not influenced, most of the investigated androgens showed depleted values after treatment. The majority of differences were found to be statistically significant and nearly all showed the expected trend towards more depleted δ(13)C-values. These results support the hypothesis of different CIR at different production sites inside the human body. The impact of these findings on doping control analysis will be discussed.

  19. Transhydrogenase and Growth Substrate Influence Lipid Hydrogen Isotope Ratios in Desulfovibrio alaskensis G20

    PubMed Central

    Leavitt, William D.; Flynn, Theodore M.; Suess, Melanie K.; Bradley, Alexander S.

    2016-01-01

    Microbial fatty acids preserve metabolic and environmental information in their hydrogen isotope ratios (2H/1H). This ratio is influenced by parameters that include the 2H/1H of water in the microbial growth environment, and biosynthetic fractionations between water and lipid. In some microbes, this biosynthetic fractionation has been shown to vary systematically with central energy metabolism, and controls on fatty acid 2H/1H may be linked to the intracellular production of NADPH. We examined the apparent fractionation between media water and the fatty acids produced by Desulfovibrio alaskensis G20. Growth was in batch culture with malate as an electron donor for sulfate respiration, and with pyruvate and fumarate as substrates for fermentation and for sulfate respiration. A larger fractionation was observed as a consequence of respiratory or fermentative growth on pyruvate than growth on fumarate or malate. This difference correlates with opposite apparent flows of electrons through the electron bifurcating/confurcating transhydrogenase NfnAB. When grown on malate or fumarate, mutant strains of D. alaskensis G20 containing transposon disruptions in a copy of nfnAB show different fractionations than the wild type strain. This phenotype is muted during fermentative growth on pyruvate, and it is absent when pyruvate is a substrate for sulfate reduction. All strains and conditions produced similar fatty acid profiles, and the 2H/1H of individual lipids changed in concert with the mass-weighted average. Unsaturated fatty acids were generally depleted in 2H relative to their saturated homologs, and anteiso-branched fatty acids were generally depleted in 2H relative to straight-chain fatty acids. Fractionation correlated with growth rate, a pattern that has also been observed in the fractionation of sulfur isotopes during dissimilatory sulfate reduction by sulfate-reducing bacteria. PMID:27445998

  20. An interlaboratory study to test instrument performance of hydrogen dual-inlet isotope-ratio mass spectrometers

    USGS Publications Warehouse

    Brand, Willi A.; Coplen, T.B.

    2001-01-01

    An interlaboratory comparison of forty isotope-ratio mass spectrometers of different ages from several vendors has been performed to test 2H/1H performance with hydrogen gases of three different isotopic compositions. The isotope-ratio results (unsufficiently corrected for H3+ contribution to the m/z = 3 collector, uncorrected for valve leakage in the change-over valves, etc.) expressed relative to one of these three gases covered a wide range of values: -630??? to -790??? for the second gas and -368??? to -462??? for the third gas. After normalizing the isotopic abundances of these test gases (linearly adjusting the ?? values so that the gases with the lowest and highest 2H content were identical for all laboratories), the standard deviation of the 40 measurements of the intermediate gas was a remarkably low 0.85???. It is concluded that the use of scaling factors is mandatory for providing accurate internationally comparable isotope-abundance values. Linear scaling for the isotope-ratio scales of gaseous hydrogen mass spectrometers is completely adequate. ?? Springer-Verlag 2001.

  1. Novel proxies for reconstructing paleohydrology from ombrotrophic peatlands: biomarker and compound-specific H and C stable isotope ratios

    NASA Astrophysics Data System (ADS)

    Wang, J.; Nichols, J. E.; Huang, Y.

    2008-12-01

    Ombrotrophic peatlands are excellent archives for paleohydrologic information because they are hydrologically isolated from their surroundings. However, quantitative proxies for deciphering peatland archives are lacking. Here, we present development and application of novel organic geochemical methods for quantitative reconstruction of paleohydrology from the ombrotrophic sediments, and comparison of organic geochemical data with conventional paleoecological proxies. Application of these methods to the sediments of several North American and European peatlands has revealed significant changes in the hydroclimate throughout the Holocene. The plant assemblage living at the surface of the peatland is tightly controlled by surface moisture. Under wet conditions, Sphagnum mosses, with no active mechanism for drawing water from below the surface of the peatland, are dominant. During dry conditions, vascular plants are more productive relative to Sphagnum. A ratio of the abundance of two biomarkers representing Sphagnum and vascular plants sensitively records changes in hydrologic balance (Nichols et al., 2006, Org. Geochem. 37, 1505-1513). We have further developed stable isotope models to compute climate parameters from compound-specific H and C isotope ratios of biomarkers to create a more comprehensive climate reconstruction. Vascular plant leaf waxes carry the D/H ratio signature of precipitation that is little affected by evaporation, whereas the Sphagnum biomarker records isotopic ratios of the water at the peatland surface, which is strongly enriched by evaporation. Evaporation amount can be calculated using the differences between D/H ratios of the two types of biomarkers. C isotope ratios of Sphagnum biomarkers can also be used to quantify surface wetness. Methanotrophic bacteria live symbiotically with Sphagnum, providing isotopically light carbon for photosynthesis. These bacteria are more active when the Sphagnum is wet, thus providing more 13C-depleted CO2

  2. Preliminary study to characterize plastic polymers using elemental analyser/isotope ratio mass spectrometry (EA/IRMS).

    PubMed

    Berto, Daniela; Rampazzo, Federico; Gion, Claudia; Noventa, Seta; Ronchi, Francesca; Traldi, Umberto; Giorgi, Giordano; Cicero, Anna Maria; Giovanardi, Otello

    2017-06-01

    Plastic waste is a growing global environmental problem, particularly in the marine ecosystems, in consideration of its persistence. The monitoring of the plastic waste has become a global issue, as reported by several surveillance guidelines proposed by Regional Sea Conventions (OSPAR, UNEP) and appointed by the EU Marine Strategy Framework Directive. Policy responses to plastic waste vary at many levels, ranging from beach clean-up to bans on the commercialization of plastic bags and to Regional Plans for waste management and recycling. Moreover, in recent years, the production of plant-derived biodegradable plastic polymers has assumed increasing importance. This study reports the first preliminary characterization of carbon stable isotopes (δ(13)C) of different plastic polymers (petroleum- and plant-derived) in order to increase the dataset of isotopic values as a tool for further investigation in different fields of polymers research as well as in the marine environment surveillance. The δ(13)C values determined in different packaging for food uses reflect the plant origin of "BIO" materials, whereas the recycled plastic materials displayed a δ(13)C signatures between plant- and petroleum-derived polymers source. In a preliminary estimation, the different colours of plastic did not affect the variability of δ(13)C values, whereas the abiotic and biotic degradation processes that occurred in the plastic materials collected on beaches and in seawater, showed less negative δ(13)C values. A preliminary experimental field test confirmed these results. The advantages offered by isotope ratio mass spectrometry with respect to other analytical methods used to characterize the composition of plastic polymers are: high sensitivity, small amount of material required, rapidity of analysis, low cost and no limitation in black/dark samples compared with spectroscopic analysis.

  3. Investigating surface water-well interaction using stable isotope ratios of water

    USGS Publications Warehouse

    Hunt, R.J.; Coplen, T.B.; Haas, N.L.; Saad, D.A.; Borchardt, M. A.

    2005-01-01

    Because surface water can be a source of undesirable water quality in a drinking water well, an understanding of the amount of surface water and its travel time to the well is needed to assess a well's vulnerability. Stable isotope ratios of oxygen in river water at the City of La Crosse, Wisconsin, show peak-to-peak seasonal variation greater than 4??? in 2001 and 2002. This seasonal signal was identified in 7 of 13 city municipal wells, indicating that these 7 wells have appreciable surface water contributions and are potentially vulnerable to contaminants in the surface water. When looking at wells with more than 6 sampling events, a larger variation in ??18O compositions correlated with a larger fraction of surface water, suggesting that samples collected for oxygen isotopic composition over time may be useful for identifying the vulnerability to surface water influence even if a local meteoric water line is not available. A time series of ??18O from one of the municipal wells and from a piezometer located between the river and the municipal well showed that the travel time of flood water to the municipal well was approximately 2 months; non-flood arrival times were on the order of 9 months. Four independent methods were also used to assess time of travel. Three methods (groundwater temperature arrival times at the intermediate piezometer, virus-culture results, and particle tracking using a numerical groundwater-flow model) yielded flood and non-flood travel times of less than 1 year for this site. Age dating of one groundwater sample using 3H-3He methods estimated an age longer than 1 year, but was likely confounded by deviations from piston flow as noted by others. Chlorofluorocarbons and SF6 analyses were not useful at this site due to degradation and contamination, respectively. This work illustrates the utility of stable hydrogen and oxygen isotope ratios of water to determine the contribution and travel time of surface water in groundwater, and

  4. Stable isotope analysis reveals community-level variation in fish trophodynamics across a fringing coral reef

    NASA Astrophysics Data System (ADS)

    Wyatt, A. S. J.; Waite, A. M.; Humphries, S.

    2012-12-01

    In contrast to trophodynamic variations, the marked zonation in physical and biological processes across coral reefs and the concomitant changes in habitat and community structure are well documented. In this study, we demonstrate consistent spatial changes in the community-level trophodynamics of 46 species of fish across the fringing Ningaloo Reef, Western Australia, using tissue stable isotope and fatty acid analyses. Increasing nitrogen (δ15N) and decreasing carbon (δ13C) isotope ratios in the tissues of herbivores, planktivores and carnivores with increasing proximity to the ocean were indicative of increased reliance on oceanic productivity. In contrast, detritivores and corallivores displayed no spatial change in δ15N or δ13C, indicative of the dependence on reef-derived material across the reef. Higher δ13C, as well as increased benthic- and bacterial-specific fatty acids, suggested reliance on reef-derived production increased in back-reef habitats. Genus-level analyses supported community- and trophic group-level trends, with isotope modelling of species from five genera ( Abudefduf sexfasciatus, Chromis viridis, Dascyllus spp., Pomacentrus spp. and Stegastes spp.), demonstrating declining access to oceanic zooplankton and, in the case of Pomacentrus spp. and Stegastes spp., a switch to herbivory in the back-reef. The spatial changes in fish trophodynamics suggest that the relative roles of oceanic and reef-derived nutrients warrant more detailed consideration in reef-level community ecology.

  5. Level densities and thermodynamical properties of Pt and Au isotopes

    NASA Astrophysics Data System (ADS)

    Giacoppo, F.; Bello Garrote, F. L.; Bernstein, L. A.; Bleuel, D. L.; Eriksen, T. K.; Firestone, R. B.; Görgen, A.; Guttormsen, M.; Hagen, T. W.; Kheswa, B. V.; Klintefjord, M.; Koehler, P. E.; Larsen, A. C.; Nyhus, H. T.; Renstrøm, T.; Sahin, E.; Siem, S.; Tornyi, T.

    2014-11-01

    The nuclear level densities of Pt-196194 and Au,198197 below the neutron separation energy have been measured using transfer and scattering reactions. All the level density distributions follow the constant-temperature description. Each group of isotopes is characterized by the same temperature above the energy threshold corresponding to the breaking of the first Cooper pair. A constant entropy excess Δ S =1.9 kB and 1.1 kB is observed in 195Pt and 198Au with respect to 196Pt and 197Au, respectively, giving information on the available single-particle level space for the last unpaired valence neutron. The breaking of nucleon Cooper pairs is revealed by sequential peaks in the microcanonical caloric curve.

  6. VizieR Online Data Catalog: C and O isotopic ratios in Arcturus and Aldebaran (Abia+ 2012)

    NASA Astrophysics Data System (ADS)

    Abia, C.; Palmerini, S.; Busso, M.; Cristallo, S.

    2012-10-01

    CNO abundances, C and O isotopic ratios and equivalent diffusive coefficients (D) are given for the calculated extra-mixing models. For Arcturus we used the electronic version of the Infrared Atlas Spectrum by Hinkle et al. (1995, Cat. J/PASP/107/1042; resolution 0.01cm-1), and for Aldebaran we used a spectrum obtained on February 6, 1980 at the KPNO 4m Coude telescope using a Fourier transform spectrometer, kindly provided by K. Hinkle (resolution 0.016cm-1) The first 2 rows of table4 report the CNO abundances and isotopic ratios resulting from the observations. The other rows give the CNO abundances and isotopic ratios accounted for by the FDU in the three stellar models considered of 1.3Mo, 1.2Mo and 1.08Mo (see the paper for more details). (1 data file).

  7. Zinc isotope ratios of bones and teeth as new dietary indicators: results from a modern food web (Koobi Fora, Kenya)

    PubMed Central

    Jaouen, Klervia; Beasley, Melanie; Schoeninger, Margaret; Hublin, Jean-Jacques; Richards, Michael P.

    2016-01-01

    In order to explore the possibilities of using zinc (Zn) stable isotope ratios as dietary indicators, we report here on the measurements of the ratio of stable isotopes of zinc (66Zn/64Zn, expressed here as δ66Zn) in bioapatite (bone and dental enamel) of animals from a modern food web in the Koobi Fora region of the Turkana Basin in Kenya. We demonstrate that δ66Zn values in both bone and enamel allow a clear distinction between carnivores and herbivores from this food web. Differences were also observed between browsers and grazers as well as between carnivores that consumed bone (i.e. hyenas) compared to those that largely consume flesh (i.e. lions). We conclude that Zn isotope ratio measurements of bone and teeth are a new and promising dietary indicator. PMID:27189145

  8. Zinc isotope ratios of bones and teeth as new dietary indicators: results from a modern food web (Koobi Fora, Kenya)

    NASA Astrophysics Data System (ADS)

    Jaouen, Klervia; Beasley, Melanie; Schoeninger, Margaret; Hublin, Jean-Jacques; Richards, Michael P.

    2016-05-01

    In order to explore the possibilities of using zinc (Zn) stable isotope ratios as dietary indicators, we report here on the measurements of the ratio of stable isotopes of zinc (66Zn/64Zn, expressed here as δ66Zn) in bioapatite (bone and dental enamel) of animals from a modern food web in the Koobi Fora region of the Turkana Basin in Kenya. We demonstrate that δ66Zn values in both bone and enamel allow a clear distinction between carnivores and herbivores from this food web. Differences were also observed between browsers and grazers as well as between carnivores that consumed bone (i.e. hyenas) compared to those that largely consume flesh (i.e. lions). We conclude that Zn isotope ratio measurements of bone and teeth are a new and promising dietary indicator.

  9. Isotopic ratio analysis of cattle tail hair: A potential tool in building the database for cow milk geographical traceability.

    PubMed

    Behkami, Shima; Zain, Sharifuddin Md; Gholami, Mehrdad; Bakirdere, Sezgin

    2017-02-15

    The potential for the isotopic ratio analysis of cattle tail hair in determining the geographical origin of raw cow milk in Peninsular Malaysia had been investigated in this research using exploratory visualization. A significant positive correlation (p<0.0001) (n=54) was noticed between δ(13)C and δ(15)N in milk with that of hair which indicated that these matrices could be used in tracing the geographical origin of animal produce and tissues, and there is a possibility that hair could be used as a substitute in building the database for the geographical traceability of milk. It was also observed that both hair and milk isotopic ratio correlations exhibited separation between the northern and southern regions. The accuracy of using isotopic ratio in determining geographical discrimination had been clearly demonstrated when several commercial milk samples from the same regions under the study were correctly assigned to the appropriate geographical clusters.

  10. Measurement of 13C/12C of chloroacetic acids by gas chromatography/combustion/isotope ratio mass spectrometry.

    PubMed

    Wong, Charles S; Muir, Derek C G; Mabury, Scott A

    2003-02-01

    This paper describes a novel analytical methodology using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to measure the 13C/12C ratios of chloroacetic acids (CAAs). CAAs are a major class of environmental pollutants that are widely distributed throughout the world, often at relatively high concentrations, and are of concern due to their toxic effects, particularly on plants. The 13C/12C of CAA reagents was measured by IRMS subsequent to offline combustion. Aqueous solutions of these CAAs were derivatized to the corresponding methyl chloroacetates (MCAAs) with acidic methanol with a known isotopic composition, extracted into pentane, and analyzed by GC/C/IRMS. Measured 13C/12C ratios of derivatized MCAAs were in agreement with calculated values within 1 per thousand for monochloroacetic acid and trichloroacetic acid and within 2 per thousand for dichloroacetic acid, suggesting that methylation and other analytical methodology steps do not isotopically fractionate derivatized MCAAs. 13C/12C ratios of reagent CAAs from different sources had varying isotopic signatures suggesting differences in source carbon and/or production methods. Our results underscore the potential of stable isotopes to serve as tracers of environmental sources of CAAs.

  11. Rate equation model of laser induced bias in uranium isotope ratios measured by resonance ionization mass spectrometry

    DOE PAGES

    Isselhardt, B. H.; Prussin, S. G.; Savina, M. R.; ...

    2015-12-07

    Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process between uranium atoms and potential isobars without the aid of chemical purification and separation. The use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of the 235U/238U ratio to decrease laser-induced isotopic fractionation. In application, isotope standards are used to identify and correct bias in measured isotope ratios, but understanding laser-induced bias from first-principles can improve the precision and accuracy of experimental measurements. A rate equationmore » model for predicting the relative ionization probability has been developed to study the effect of variations in laser parameters on the measured isotope ratio. The model uses atomic data and empirical descriptions of laser performance to estimate the laser-induced bias expected in experimental measurements of the 235U/238U ratio. Empirical corrections are also included to account for ionization processes that are difficult to calculate from first principles with the available atomic data. As a result, development of this model has highlighted several important considerations for properly interpreting experimental results.« less

  12. Rate equation model of laser induced bias in uranium isotope ratios measured by resonance ionization mass spectrometry

    SciTech Connect

    Isselhardt, B. H.; Prussin, S. G.; Savina, M. R.; Willingham, D. G.; Knight, K. B.; Hutcheon, I. D.

    2015-12-07

    Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process between uranium atoms and potential isobars without the aid of chemical purification and separation. The use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of the 235U/238U ratio to decrease laser-induced isotopic fractionation. In application, isotope standards are used to identify and correct bias in measured isotope ratios, but understanding laser-induced bias from first-principles can improve the precision and accuracy of experimental measurements. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variations in laser parameters on the measured isotope ratio. The model uses atomic data and empirical descriptions of laser performance to estimate the laser-induced bias expected in experimental measurements of the 235U/238U ratio. Empirical corrections are also included to account for ionization processes that are difficult to calculate from first principles with the available atomic data. As a result, development of this model has highlighted several important considerations for properly interpreting experimental results.

  13. Isotopic niche variation in a higher trophic level ectotherm: highlighting the role of succulent plants in desert food webs.

    PubMed

    Delibes, Miguel; Blazquez, Ma Carmen; Fedriani, Jose Maria; Granados, Arsenio; Soriano, Laura; Delgado, Antonio

    2015-01-01

    Stable isotope analysis of animal tissues allows description of isotopic niches, whose axes in an n-dimensional space are the isotopic ratios, compared to a standard, of different isotope systems (e.g. δ(13)C, δ(15)N). Isotopic niches are informative about where an animal, population or species lives and about what it consumes. Here we describe inter- and intrapopulation isotopic niche (bidimensional δ(13)C-δ(15)N space) of the Orange-throated whiptail (Aspidoscelis hyperythra), an arthropodivorous small lizard, in ten localities of Baja California Sur (Mexico). These localities range from extreme arid to subtropical conditions. Between 13 and 20 individuals were sampled at each locality and 1 cm of tail-tip was collected for isotope analysis. As expected, interpopulation niche width variation was much larger than intrapopulation one. Besides, isotopic variation was not related to age, sex or individual size of lizards. This suggests geographic variation of the isotopic niche was related to changes in the basal resources that fuel the trophic web at each locality. The position of Bayesian isotope ellipses in the δ-space indicated that whiptails in more arid localities were enriched in 13C, suggesting most of the carbon they ingested came from CAM succulent plants (cacti, agaves) and in minor degree in C4 grasses. Contrarily, whiptails in subtropical areas were depleted in 13C, as they received more carbon from C3 scrubs and trees. Localities closer to sea-level tended to be enriched in 15N, but a clear influence of marine subsidies was detected only at individual level. The study contributes to identify the origin and pathways through which energy flows across the trophic webs of North American deserts.

  14. Isotopic Niche Variation in a Higher Trophic Level Ectotherm: Highlighting the Role of Succulent Plants in Desert Food Webs

    PubMed Central

    Delibes, Miguel; Blazquez, Ma Carmen; Fedriani, Jose Maria; Granados, Arsenio; Soriano, Laura; Delgado, Antonio

    2015-01-01

    Stable isotope analysis of animal tissues allows description of isotopic niches, whose axes in an n-dimensional space are the isotopic ratios, compared to a standard, of different isotope systems (e.g. δ13C, δ15N). Isotopic niches are informative about where an animal, population or species lives and about what it consumes. Here we describe inter- and intrapopulation isotopic niche (bidimensional δ13C-δ15N space) of the Orange-throated whiptail (Aspidoscelis hyperythra), an arthropodivorous small lizard, in ten localities of Baja California Sur (Mexico). These localities range from extreme arid to subtropical conditions. Between 13 and 20 individuals were sampled at each locality and 1 cm of tail-tip was collected for isotope analysis. As expected, interpopulation niche width variation was much larger than intrapopulation one. Besides, isotopic variation was not related to age, sex or individual size of lizards. This suggests geographic variation of the isotopic niche was related to changes in the basal resources that fuel the trophic web at each locality. The position of Bayesian isotope ellipses in the δ-space indicated that whiptails in more arid localities were enriched in 13C, suggesting most of the carbon they ingested came from CAM succulent plants (cacti, agaves) and in minor degree in C4 grasses. Contrarily, whiptails in subtropical areas were depleted in 13C, as they received more carbon from C3 scrubs and trees. Localities closer to sea-level tended to be enriched in 15N, but a clear influence of marine subsidies was detected only at individual level. The study contributes to identify the origin and pathways through which energy flows across the trophic webs of North American deserts. PMID:25973609

  15. Study on strontium isotope abundance-ratio measurements by using a 13-MeV proton beam

    NASA Astrophysics Data System (ADS)

    Jeong, Cheol-Ki; Jang, Han; Lee, Goung-Jin

    2016-09-01

    The Rb-Sr dating method is used in dating Paleozoic and Precambrian rocks. This method measures the 87Rb and the 87Sr concentrations by using thermal ionization mass spectrometry (TIMS) [J. Hefne et al., Inter. J. Phys. Sci. 3(1), 28 (2008)]. In addition, it calculates the initial 87Sr/86Sr ratio to increase the reliability of Rb-Sr dating. In this study, the 87Sr/86Sr ratio was measured by using a 13-MeV proton accelerator. Proton kinetic energies are in the range of tens of megaelectronvolts, and protons have large absorption cross-sections for ( p, n) reactions with most substances. After absorbing a proton with such a high kinetic energy, an element is converted into a nuclide with its atomic number increased by one via nuclear transmutation. These nuclides usually have short half-lives and return to the original state through radioactive decay. When a strontium sample is irradiated with protons, nuclear transmutation occurs; thus, the strontium isotope present in the sample changes to a yttrium isotope, which is an activated radioisotope. Based on this, the 87Sr/86Sr ratio was calculated by analyzing the gamma-rays emitted by each yttrium isotope. The KIRAMS-13 cyclotron at the Cyclotron Center of Chosun University, where 13-MeV protons can be extracted, was utilized in our experiment. The 87Sr/86Sr isotope ratio was computed for samples irradiated with these protons, and the result was similar to the isotope ratio for the Standard Reference Material, i.e., 98.2 ± 3.4%. As part of the analysis, proton activation analyses were performed using 13-MeV protons, and the experimental results of this research suggest a possible approach for measuring the strontium-isotope abundance ratio of samples.

  16. δ13C and δ18O isotopic composition of CaCO3 measured by continuous flow isotope ratio mass spectrometry: statistical evaluation and verification by application to Devils Hole core DH-11 calcite

    USGS Publications Warehouse

    Revesz, Kinga M.; Landwehr, Jurate M.

    2002-01-01

    A new method was developed to analyze the stable carbon and oxygen isotope ratios of small samples (400 ± 20 µg) of calcium carbonate. This new method streamlines the classical phosphoric acid/calcium carbonate (H3PO4/CaCO3) reaction method by making use of a recently available Thermoquest-Finnigan GasBench II preparation device and a Delta Plus XL continuous flow isotope ratio mass spectrometer. Conditions for which the H3PO4/CaCO3 reaction produced reproducible and accurate results with minimal error had to be determined. When the acid/carbonate reaction temperature was kept at 26 °C and the reaction time was between 24 and 54 h, the precision of the carbon and oxygen isotope ratios for pooled samples from three reference standard materials was ≤0.1 and ≤0.2 per mill or ‰, respectively, although later analysis showed that materials from one specific standard required reaction time between 34 and 54 h for δ18O to achieve this level of precision. Aliquot screening methods were shown to further minimize the total error. The accuracy and precision of the new method were analyzed and confirmed by statistical analysis. The utility of the method was verified by analyzing calcite from Devils Hole, Nevada, for which isotope-ratio values had previously been obtained by the classical method. Devils Hole core DH-11 recently had been re-cut and re-sampled, and isotope-ratio values were obtained using the new method. The results were comparable with those obtained by the classical method with correlation = +0.96 for both isotope ratios. The consistency of the isotopic results is such that an alignment offset could be identified in the re-sampled core material, and two cutting errors that occurred during re-sampling then were confirmed independently. This result indicates that the new method is a viable alternative to the classical reaction method. In particular, the new method requires less sample material permitting finer resolution and allows

  17. Using stable isotope ratios to estimate atmospheric nitrogen fixed by cyanobacteria at the ecosystem scale.

    PubMed

    Woodland, Ryan J; Cook, Perran L M

    2014-04-01

    Diazotrophic cyanobacteria are capable of fixing atmospheric N2 to satisfy their physiological nitrogen requirements. This process can result in the transfer of substantial amounts of "new" diazotrophic nitrogen (ND) to aquatic ecosystems during blooms of these taxa. Using in situ measurements of plankton natural abundance stable isotope composition and a combination of underway and fixed site survey data, the total N(D) flux into the Gippsland Lakes estuary (Australia) was estimated during a summer bloom of the diazotrophic cyanobacterium Nodularia spumigena. Over the course of the bloom, N(D) increased in the upper water column of the estuary from 33% +/- 17% (mean +/- SD) to 73% +/- 13% of the standing pool of total particulate N. A conservative estimate of total N(D) flux (146 Mg) equates to an estimated 177% of the summer total N load and 22% of the annual total N load to the estuary. Combining natural abundance stable isotope measurements with relatively simple fixed and underway survey designs can provide a cost-effective approach for monitoring the N(D) flux into estuary or lacustrine environments. This approach relies on an isotopic differential between the diazotrophic and the non-diazotrophic components of the plankton community; it may not be appropriate in ecosystems that experience low-level blooms or blooms of intermittent N-fixing cyanobacteria. Large-scale blooms of diazotrophic cyanobacteria are considered uncommon in estuaries, yet it is clear that these blooms can represent major sources of new N to estuarine ecosystems when and where they occur.

  18. Oxygen isotope ratios in the shell of Mytilus edulis: archives of glacier meltwater in Greenland?

    NASA Astrophysics Data System (ADS)

    Versteegh, E. A. A.; Blicher, M. E.; Mortensen, J.; Rysgaard, S.; Als, T. D.; Wanamaker, A. D., Jr.

    2012-09-01

    Melting of the Greenland Ice Sheet (GrIS) is accelerating and will contribute significantly to global sea level rise during the 21st century. Instrumental data on GrIS melting only cover the last few decades, and proxy data extending our knowledge into the past are vital for validating models predicting the influence of ongoing climate change. We investigated a potential meltwater proxy in Godthåbsfjord (West Greenland), where glacier meltwater causes seasonal excursions with lower oxygen isotope water (δ18Ow) values and salinity. The blue mussel (Mytilus edulis) potentially records these variations, because it precipitates its shell calcite in oxygen isotopic equilibrium with ambient seawater. As M. edulis shells are known to occur in raised shorelines and kitchen middens from previous Holocene warm periods, this species may be ideal in reconstructing past meltwater dynamics. We investigate its potential as a palaeo-meltwater proxy. First, we confirmed that M. edulis shell calcite oxygen isotope (δ18Oc) values are in equilibrium with ambient water and generally reflect meltwater conditions. Subsequently we investigated if this species recorded the full range of δ18Ow values occurring during the years 2007 to 2010. Results show that δ18Ow values were not recorded at very low salinities (< ~19), because the mussels appear to cease growing. This implies that M. edulis δ18Oc values are suitable in reconstructing past meltwater amounts in most cases, but care has to be taken that shells are collected not too close to a glacier, but rather in the mid region or mouth of the fjord. The focus of future research will expand on the geographical and temporal range of the shell measurements by sampling mussels in other fjords in Greenland along a south-north gradient, and by sampling shells from raised shorelines and kitchen middens from prehistoric settlements in Greenland.

  19. Simulation of stable isotopic pools and fluxes by a land-surface scheme forced with observed isotopic ratios in precipitation and atmospheric water vapour.

    NASA Astrophysics Data System (ADS)

    Henderson-Sellers, A.; Griffith, D.; Irannejad, P.; Williams, A.; Stone, D.

    2004-12-01

    Stable isotopes provide independent tools for evaluating key components of the hydrological and carbon cycles as simulated by land-surface schemes (LSS). The Project for Intercomparison of Land-surface Parameterisation Schemes (PILPS http://www.pilps.mq.edu.au) is initiating a new type of experiment (IPILPS) to assess the ability of LSSs to reproduce isotopic components of water and mass (carbon) budgets. The project aims to intercompare LSS simulations of diurnal and annual cycles of isotopic pools and fluxes, and to evaluate the performance of isotope-enabled LSSs under varying environmental conditions. The need for evaluation data is driving a new experimental effort concentrating on the measurement of stable water isotopes (SWI), in precipitation, atmospheric and canopy water vapour, soil water and leaf/stem water, on annual and diurnal time scales at three sites in the GEWEX CSE Amazon, Murray-Darling and Baltic Sea basins. We present diurnal and annual cycles of stable isotopes in the ecosystem as simulated by an isotope enabled LSS (ISOLSM)1 over an agricultural pasture in Wagga Wagga (SE Australia). Climatological values of SWI in precipitation and water vapour, as well as continuous in situ D/H ratios of atmospheric water vapour obtained during a three-week field campaign, are used to force the LSS. The D/H ratio was measured using a fully automated and mobile Fourier Transform Infrared (FTIR)2 spectrometer. The sensitivity of simulated isotopes (in soil water, plants and canopy air space, as well as isotopic exchanges between the land surface and the atmosphere) to the atmospheric forcing is analysed. The results highlight the importance of intensive field campaigns for measuring SWI in the environment as both forcing and evaluation data for land surface simulations. 1. A. Henderson-Sellers et al., 2004, Using stable water isotopes to evaluate basin-scale simulations of surface water budgets, in press, J. Hydrometeorol. 2. D.W.T. Griffith et al., 2002

  20. Estimating distributions of endogenous and exogenous Pb in soils by using Pb isotopic ratios.

    PubMed

    Semlali, R M; van Oort, F; Denaix, L; Loubet, M

    2001-11-01

    Metal contamination of soils by diffuse atmospheric deposition is a worldwide phenomenon. The assessment of incorporation of exogenous metal contaminants in soils is of major environmental importance. Once entering in the soil's biogeochemical cycling, specific pedogenetic soil processes govern metal distribution patterns with depth. In this paper, we attempt to estimate the distribution of endogenous and exogenous Pb in two soils with contrasting pedogenesis, both representative of undisturbed ecosystems. Pb isotope analyses were performed using high-precision thermal ionization mass spectrometry. Endogenous and exogenous Pb concentrations and exogenous 206Pb/207Pb ratios of the samples were calculated using bulk Pb and Sc concentrations and bulk 206Pb/207Pb ratios. Endogenous Pb distribution was in agreementwith dominant soil characteristics, almost constant in the young Andosol and with a clear minimum and maximum in the eluvial and illuvial horizons of the Podzol. The distribution of exogenous Pb was closely related to that of organic C in both soils. Exogenous Pb was evidenced in significant amounts at depth. Using moderate dispersive particle-size fractionation allowed us to evidence the presence of exogenous Pb in functional soil compartments and to highlight preferential distributions of Pb, according to pedology.

  1. Isotopic Ratios in Nitriles from Submillimeter Spectroscopy Using SMA and ALMA

    NASA Astrophysics Data System (ADS)

    Gurwell, Mark A.; Moreno, Raphael; Vinatier, Sandrine; Lellouch, Emmanuel; Butler, Bryan J.; Moullet, Arielle; Lara, Luisa; Hidayat, Taufiq

    2016-10-01

    We present submillimeter spectroscopic observations of Titan obtained using the Submillimeter Array (SMA) in 2011, and the Atacama Large Millimeter/Submillimeter Array (ALMA) in 2012, some of which have previously been presented but not fully analyzed (1, 2, 3). The SMA observations were obtained at low spatial resolution, providing disk average spectra, but the ALMA observations provide low resolution mapping of Titan (~0.4"-0.6" when Titan was 0.77" surface diameter). We will present detailed radiative transfer analysis of detected spectral lines to derive isotopic ratios in two nitriles: HCN (D/H, 13C/12C, 15N/14N) and HC3N (15N/14N). The analysis makes use of nearly concurrent CIRS temperature profiles as important constraints for the vertical profiles of these species, allowing high precision measurements of the ratios. Finally, we will highlight current and future ALMA observations that will allow monitoring of non-symmetric molecular species in Titan's upper atmosphere from Earth, beyond the end of the Cassini mission.(1) Gurwell et al (2011) EPSC-DPS Joint Meeting 2011, p270. (2) Moreno et al (2014) EPSC 2014 Abstracts, Vol. 9, id. EPSC2014-438. (3) Moreno etal (2014), DPS meeting #46, id.211.19

  2. Stable mercury isotope ratios as tracers for Hg cycling at the inoperative New Idria Hg mine, California

    NASA Astrophysics Data System (ADS)

    Wiederhold, J. G.; Jew, A. D.; Brown, G. E.; Bourdon, B.; Kretzschmar, R.

    2010-12-01

    The seven stable isotopes of Hg are fractionated in the environment as a result of mass-dependent (MDF) and mass-independent (MIF) fractionation processes that can be studied in parallel by analyzing the ratios of even and odd mass Hg isotopes. MDF and MIF Hg isotope signatures of natural samples may provide a new tool to trace sources and transformations in environmental Hg cycling. However, the mechanisms controlling the extent of kinetic and equilibrium Hg isotope fractionations are still only partially understood. Thus, development of this promising tracer requires experimental calibration of relevant fractionation factors as well as assessment of natural variations of Hg isotope ratios under different environmental conditions. The inoperative Hg mine in New Idria (California, USA) represents an ideal case study to explore Hg isotope fractionation during Hg transformation and transport processes. More than a century of Hg mining and on-site thermal refining to obtain elemental Hg until 1972 produced large volumes of contaminated mine wastes which now represent sources of Hg pollution for the surrounding ecosystems. Here, we present Hg isotope data from various materials collected at New Idria using Cold-Vapor-MC-ICPMS with a long-term δ202Hg reproducibility of ±0.1‰ (2SD). Uncalcined mine waste samples were isotopically similar to NIST-3133 and did not exhibit any MIF signatures. In contrast, calcine samples, which represent the residue of the thermal ore processing at 700°C, had significantly heavier δ202Hg values of up to +1.5‰. In addition, we observed small negative MIF anomalies of the odd-mass Hg isotopes in the calcine samples, which could be caused either by nuclear volume fractionation or a magnetic isotope effect during or after the roasting process. The mass-dependent enrichment of heavy Hg isotopes in the calcine materials indicates that light Hg isotopes were preferentially removed during the roasting process, in agreement with a previous

  3. Oxygen stable isotope ratios from British oak tree-rings provide a strong and consistent record of past changes in summer rainfall

    NASA Astrophysics Data System (ADS)

    Young, Giles H. F.; Loader, Neil J.; McCarroll, Danny; Bale, Roderick J.; Demmler, Joanne C.; Miles, Daniel; Nayling, Nigel T.; Rinne, Katja T.; Robertson, Iain; Watts, Camilla; Whitney, Matthew

    2015-12-01

    United Kingdom (UK) summers dominated by anti-cyclonic circulation patterns are characterised by clear skies, warm temperatures, low precipitation totals, low air humidity and more enriched oxygen isotope ratios (δ18O) in precipitation. Such conditions usually result in relatively more positive (enriched) oxygen isotope ratios in tree leaf sugars and ultimately in the tree-ring cellulose formed in that year, the converse being true in cooler, wet summers dominated by westerly air flow and cyclonic conditions. There should therefore be a strong link between tree-ring δ18O and the amount of summer precipitation. Stable oxygen isotope ratios from the latewood cellulose of 40 oak trees sampled at eight locations across Great Britain produce a mean δ18O chronology that correlates strongly and significantly with summer indices of total shear vorticity, surface air pressure, and the amount of summer precipitation across the England and Wales region of the United Kingdom. The isotope-based rainfall signal is stronger and much more stable over time than reconstructions based upon oak ring widths. Using recently developed methods that are precise, efficient and highly cost-effective it is possible to measure both carbon (δ13C) and oxygen (δ18O) isotope ratios simultaneously from the same tree-ring cellulose. In our study region, these two measurements from multiple trees can be used to reconstruct summer temperature (δ13C) and summer precipitation (δ18O) with sufficient independence to allow the evolution of these climate parameters to be reconstructed with high levels of confidence. The existence of long, well-replicated oak tree-ring chronologies across the British Isles mean that it should now be possible to reconstruct both summer temperature and precipitation over many centuries and potentially millennia.

  4. Performance of isotope ratio infrared spectroscopy (IRIS) for analyzing waters containing organic contaminants: Problems and solutions (Invited)

    NASA Astrophysics Data System (ADS)

    West, A. G.; Goldsmith, G. R.; Dawson, T. E.

    2010-12-01

    The development of isotope ratio infrared spectroscopy (IRIS) for simultaneous δ2H and δ18O analysis of liquid water samples shows much potential for affordable, simple and potentially portable isotopic analyses. IRIS has been shown to be comparable in precision and accuracy to isotope ratio mass spectrometry (IRMS) when analyzing pure water samples. However, recent studies have shown that organic contaminants in analyzed water samples may interfere with the spectroscopy leading to errors of considerable magnitude in the reported stable isotope data. Many environmental, biological and forensic studies require analyses of water containing organic contaminants in some form, yet our current methods of removing organic contaminants prior to analysis appear inadequate for IRIS. Treated plant water extracts analyzed by IRIS showed deviations as large as 35‰ (δ2H) and 11.8‰ (δ18O) from the IRMS value, indicating that trace amounts of contaminants were sufficient to disrupt IRIS analyses. However, not all organic contaminants negatively influence IRIS. For such samples, IRIS presents a labour saving method relative to IRMS. Prior to widespread use in the environmental, biological and forensic sciences, a means of obtaining reliable data from IRIS needs to be demonstrated. One approach is to use instrument-based software to flag potentially problematic spectra and output a corrected isotope value based on analysis of the spectra. We evaluate this approach on two IRIS systems and discuss the way forward for ensuring accurate stable isotope data using IRIS.

  5. Probing the metabolic water contribution to intracellular water using oxygen isotope ratios of PO4

    PubMed Central

    Li, Hui; Yu, Chan; Wang, Fei; Chang, Sae Jung; Yao, Jun; Blake, Ruth E.

    2016-01-01

    Knowledge of the relative contributions of different water sources to intracellular fluids and body water is important for many fields of study, ranging from animal physiology to paleoclimate. The intracellular fluid environment of cells is challenging to study due to the difficulties of accessing and sampling the contents of intact cells. Previous studies of multicelled organisms, mostly mammals, have estimated body water composition—including metabolic water produced as a byproduct of metabolism—based on indirect measurements of fluids averaged over the whole organism (e.g., blood) combined with modeling calculations. In microbial cells and aquatic organisms, metabolic water is not generally considered to be a significant component of intracellular water, due to the assumed unimpeded diffusion of water across cell membranes. Here we show that the 18O/16O ratio of PO4 in intracellular biomolecules (e.g., DNA) directly reflects the O isotopic composition of intracellular water and thus may serve as a probe allowing direct sampling of the intracellular environment. We present two independent lines of evidence showing a significant contribution of metabolic water to the intracellular water of three environmentally diverse strains of bacteria. Our results indicate that ∼30–40% of O in PO4 comprising DNA/biomass in early stationary phase cells is derived from metabolic water, which bolsters previous results and also further suggests a constant metabolic water value for cells grown under similar conditions. These results suggest that previous studies assuming identical isotopic compositions for intracellular/extracellular water may need to be reconsidered. PMID:27170190

  6. Probing the metabolic water contribution to intracellular water using oxygen isotope ratios of PO4

    NASA Astrophysics Data System (ADS)

    Li, Hui; Yu, Chan; Wang, Fei; Chang, Sae Jung; Yao, Jun; Blake, Ruth E.

    2016-05-01

    Knowledge of the relative contributions of different water sources to intracellular fluids and body water is important for many fields of study, ranging from animal physiology to paleoclimate. The intracellular fluid environment of cells is challenging to study due to the difficulties of accessing and sampling the contents of intact cells. Previous studies of multicelled organisms, mostly mammals, have estimated body water composition—including metabolic water produced as a byproduct of metabolism—based on indirect measurements of fluids averaged over the whole organism (e.g., blood) combined with modeling calculations. In microbial cells and aquatic organisms, metabolic water is not generally considered to be a significant component of intracellular water, due to the assumed unimpeded diffusion of water across cell membranes. Here we show that the 18O/16O ratio of PO4 in intracellular biomolecules (e.g., DNA) directly reflects the O isotopic composition of intracellular water and thus may serve as a probe allowing direct sampling of the intracellular environment. We present two independent lines of evidence showing a significant contribution of metabolic water to the intracellular water of three environmentally diverse strains of bacteria. Our results indicate that ˜30-40% of O in PO4 comprising DNA/biomass in early stationary phase cells is derived from metabolic water, which bolsters previous results and also further suggests a constant metabolic water value for cells grown under similar conditions. These results suggest that previous studies assuming identical isotopic compositions for intracellular/extracellular water may need to be reconsidered.

  7. Phosphate oxygen isotope ratio proxy for specific microbial activity in marine sediments (Peru Margin)

    NASA Astrophysics Data System (ADS)

    Liang, Y.; Blake, R. E.

    2005-12-01

    Oxygen (O) isotope ratios of biogenic apatites have been widely used as paleotemperature and environmental geochemical proxies. With improved knowledge of the phosphate O isotope effects of different P cycling pathways, the δ18O value of inorganic phosphate (δ18OP) has been proposed as a useful proxy and tracer of biological reactions and P cycling in natural environments[1,2,3,4]. Being the only way of removing P from oceanic water, sedimentary P burial is one of the most important processes during biogeochemical cycling of P. The high concentrations of organic matter and pronounced microbial activity at ODP Site 1230 along the Peru Margin result in unusually high interstitial water phosphate concentrations, which provides a unique opportunity to use δ18OP to investigate inorganic phosphate (Pi) regeneration and P cycling pathways in marine sediments. The isotopic measurements of both dissolved inorganic phosphate (DIP) and bulk sediment Pi show that DIP δ18OP values are affected by three different processes, which are all induced by specific microbial activities present in the sediments. In sediments at ~ 65 to 120 mbsf, porewater DIP is derived from dissolved organophosphorus compounds (DOP) through enzymatic degradation pathways, evidenced by both DIP δ18OP values and interstitial water chemistry. Measured porewater DIP δ18OP values also suggest that 4 to 8% of interstitial water DIP reflects regeneration of Pi from Porg by microbially-synthesized enzymes. Throughout the sediment column and especially at ~ 120 to 150 mbsf, DIP is released from the sediments by microbially-induced reductive dissolution of Fe-oxides, which contributes to the overall high DIP concentrations at Site 1230. The third and dominant process controlling measured DIP δ18OP values is microbial turnover of regenerated Pi. The presence of high microbial activities in organic-rich Site 1230 sediments promotes the remobilization of P and affects marine P cycling by potentially enhancing

  8. Role of Wind and Sea Surface Temperature Over Moisture Source Region in Determining the Stable Isotopic Ratios in Rainwater

    NASA Astrophysics Data System (ADS)

    Rahul, P.; Ghosh, P.

    2012-12-01

    Rainwater stable isotope ratio is controlled by several factors such as distance from the coast, latitudinal location, altitudes, temperature and amount of rainfall (Dansgard 1964;Rozanski 1993). Amount of rainfall plays a significant role in controlling the distribution of stable isotopes especially in the tropics experiencing seasonal precipitation from monsoonal wind circulation. In recent years with more observations on rainfall stable isotopes being documented from tropical regions, the effect of parameters like wind, sea surface temperature, drop size distribution on stable isotopic composition of rainwater are better understood (Wright et al 2001;Vochon et al 2009; Rao et al 2006; Srivastava et al 2012). The isotopic compositions of 2010 ISMR (Indian Summer Monsoon Rainfall) from Bangalore, India along with a few other observations of similar kind retrieved from the literatures are studied for amount effect relationship. Bangalore region provide nice opportunity to understand the different monsoonal influence due to its location ( ~300 km ) from coastal boundaries in east and west. The air parcel back trajectories obtained from NOAA HYSPLIT shows Arabian Sea region as the prominent source of moisture for the rainfall occurring during Southwest Monsoon (SWM). In this study we investigated the role of Sea Surface temperature (SST) and wind conditions over the moisture source and its effect on the intra seasonal variability of rainfall isotopic composition recorded at Bangalore region. The isotope analysis of δ18O in rainwater during the Indian summer monsoon rainfall shows a range of values from 2.77‰ to -9.07‰ over a period covering June to September. The observations fail to establish any relationship between stable isotope ratio and rainfall amount. We observed that the temporal variability of SST and wind over Arabian Sea region having strong role in driving the isotopic composition of rainwater. The relationship between SST and isotope ratio is found

  9. Addressing the current bottlenecks of metabolomics: Isotopic Ratio Outlier Analysis™, an isotopic-labeling technique for accurate biochemical profiling.

    PubMed

    de Jong, Felice A; Beecher, Chris

    2012-09-01

    Metabolomics or biochemical profiling is a fast emerging science; however, there are still many associated bottlenecks to overcome before measurements will be considered robust. Advances in MS resolution and sensitivity, ultra pressure LC-MS, ESI, and isotopic approaches such as flux analysis and stable-isotope dilution, have made it easier to quantitate biochemicals. The digitization of mass spectrometers has simplified informatic aspects. However, issues of analytical variability, ion suppression and metabolite identification still plague metabolomics investigators. These hurdles need to be overcome for accurate metabolite quantitation not only for in vitro systems, but for complex matrices such as biofluids and tissues, before it is possible to routinely identify biomarkers that are associated with the early prediction and diagnosis of diseases. In this report, we describe a novel isotopic-labeling method that uses the creation of distinct biochemical signatures to eliminate current bottlenecks and enable accurate metabolic profiling.

  10. Analyzing Nuclear Fuel Cycles from Isotopic Ratios of Waste Products Applicable to Measurement by Accelerator Mass Spectrometry

    SciTech Connect

    Biegalski, S R; Whitney, S M; Buchholz, B

    2005-08-24

    An extensive study was conducted to determine isotopic ratios of nuclides in spent fuel that may be utilized to reveal historical characteristics of a nuclear reactor cycle. This forensic information is important to determine the origin of unknown nuclear waste. The distribution of isotopes in waste products provides information about a nuclear fuel cycle, even when the isotopes of uranium and plutonium are removed through chemical processing. Several different reactor cycles of the PWR, BWR, CANDU, and LMFBR were simulated for this work with the ORIGEN-ARP and ORIGEN 2.2 codes. The spent fuel nuclide concentrations of these reactors were analyzed to find the most informative isotopic ratios indicative of irradiation cycle length and reactor design. Special focus was given to long-lived and stable fission products that would be present many years after their creation. For such nuclides, mass spectrometry analysis methods often have better detection limits than classic gamma-ray spectroscopy. The isotopic ratios {sup 151}Sm/{sup 146}Sm, {sup 149}Sm/{sup 146}Sm, and {sup 244}Cm/{sup 246}Cm were found to be good indicators of fuel cycle length and are well suited for analysis by accelerator mass spectroscopy.

  11. Assessment of Non-traditional Isotopic Ratios by Mass Spectrometry for Analysis of Nuclear Activities: Annual Report Year 2

    SciTech Connect

    Biegalski, S; Buchholz, B

    2009-08-26

    The objective of this work is to identify isotopic ratios suitable for analysis via mass spectrometry that distinguish between commercial nuclear reactor fuel cycles, fuel cycles for weapons grade plutonium, and products from nuclear weapons explosions. Methods will also be determined to distinguish the above from medical and industrial radionuclide sources. Mass spectrometry systems will be identified that are suitable for field measurement of such isotopes in an expedient manner. Significant progress has been made with this project within the past year: (1) Isotope production from commercial nuclear fuel cycles and nuclear weapons fuel cycles have been modeled with the ORIGEN and MCNPX codes. (2) MCNPX has been utilized to calculate isotopic inventories produced in a short burst fast bare sphere reactor (to approximate the signature of a nuclear weapon). (3) Isotopic ratios have been identified that are good for distinguishing between commercial and military fuel cycles as well as between nuclear weapons and commercial nuclear fuel cycles. (4) Mass spectrometry systems have been assessed for analysis of the fission products of interest. (5) A short-list of forensic ratios have been identified that are well suited for use in portable mass spectrometry systems.

  12. Review: Current applications and challenges for liquid chromatography coupled to isotope ratio mass spectrometry (LC/IRMS).

    PubMed

    Godin, Jean-Philippe; McCullagh, James S O

    2011-10-30

    High-precision isotope analysis is recognized as an essential research tool in many fields of study. Until recently, continuous flow isotope ratio mass spectrometry (CF-IRMS) was available via an elemental analyzer or a gas chromatography inlet system for compound-specific analysis of light stable isotopes. In 2004, however, an interface that coupled liquid chromatography with IRMS (LC/IRMS) became commercially available for the first time. This brought the capability for new areas of application, in particular enabling compound-specific δ(13)C analysis of non-volatile, aqueous soluble, compounds from complex mixtures. The interface design brought with it several analytical constraints, however, in particular a lack of compatibility with certain types of chromatography as well as limited flow rates and mobile phase compositions. Routine LC/IRMS methods have, however, been established for measuring the δ(13)C isotopic ratios of underivatized individual compounds for application in archeology, nutrition and physiology, geochemistry, hydrology, soil science and food authenticity. Seven years after its introduction, we review the technical advances and constraints, methodological developments and new applications of liquid chromatography coupled to isotope ratio mass spectrometry.

  13. Standardless determination of Nd and Sr isotope ratios in geological samples using LA-MC-ICP-MS with a low-oxide molecular yield interface setup

    NASA Astrophysics Data System (ADS)

    Kimura, J.; Chang, Q.; Takahashi, T.; Kawabata, H.

    2013-12-01

    We investigated an appropriate instrumental setup for a laser-ablation multiple-collector inductively coupled plasma mass spectrometer (LA-MC-ICP-MS) and found that a reduced oxide setting allowed accurate and precise analyses of Sr and Nd isotope ratios in geological samples with concomitant interfering elements (Kr and Rb on Sr and Sm on Nd). We used an Aridus II solution-excimer laser dual-intake system. The ICP interface used normal sample and skimmer cones with torch shield switched-OFF and an additional large interface rotary pump. The setting accomplished reduced oxide levels NdO+/Nd+ <0.01%, without significant sacrifice of the instrumental sensitivity (c.a. 70%). Oxide molecular ions for the lighter elements were negligible and accurate internal mass bias corrections were achieved for Sr, Sm, and Nd using isotopic ratios derived from thermal ionization mass spectrometry measurements. However, elemental fractionation between Rb and Sr and Nd and Sm still exists due perhaps to elemental fractionation in the ICP preventing standardless determination of parent-daughter ratios. For Sr isotope measurement, a new analytical protocol was developed for correcting Kr baseline-induced biases. Residual analytical biases of 84Sr/86Sr and 87Sr/86Sr were observed after applying on-peak background subtractions and mass-fractionation corrections using internal normalization. The residual biases occurred only for samples analysed with LA and not for solution analyses using Aridus II with the same instrumental setup. We concluded that this was due to suppression and enhancement of the Kr baseline by loading of the LA sample aerosols and by the introduction of Kr from the samples, respectively. We found that both the 84Sr/86Sr and 87Sr/86Sr isotope ratios were affected proportionally by the baseline biases of the LA analyses of an isotopically homogeneous anorthite plagioclase, and similar result were seen in theoretical calculations. A theoretical bias correction for the 87