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Sample records for boron isotope ratios

  1. 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

  2. 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

  3. 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

  4. A review on the determination of isotope ratios of boron with mass spectrometry.

    PubMed

    Aggarwal, Suresh Kumar; You, Chen-Feng

    2017-07-01

    The present review discusses different mass spectrometric techniques-viz, thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (ICPMS), and secondary ion mass spectrometry (SIMS)-used to determine (11) B/(10) B isotope ratio, and concentration of boron required for various applications in earth sciences, marine geochemistry, nuclear technology, environmental, and agriculture sciences, etc. The details of the techniques-P-TIMS, which uses Cs2 BO2(+) , N-TIMS, which uses BO2(-) , and MC-ICPMS, which uses B(+) ions for bulk analysis or B(-) and B(+) ions for in situ micro-analysis with SIMS-are highlighted. The capabilities, advantages, limitations, and problems in each mass spectrometric technique are summarized. The results of international interlaboratory comparison experiments conducted at different times are summarized. The certified isotopic reference materials available for boron are also listed. Recent developments in laser ablation (LA) ICPMS and QQQ-ICPMS for solids analysis and MS/MS analysis, respectively, are included. The different aspects of sample preparation and analytical chemistry of boron are summarized. Finally, the future requirements of boron isotope ratios for future applications are also given. Presently, MC-ICPMS provides the best precision and accuracy (0.2-0.4‰) on isotope ratio measurements, whereas N-TIMS holds the potential to analyze smallest amount of boron, but has the issue of bias (+2‰ to 4‰) which needs further investigations. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:499-519, 2017. © 2016 Wiley Periodicals, Inc.

  5. 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.

  6. Determination of boron isotope ratios by high-resolution continuum source molecular absorption spectrometry using graphite furnace vaporizers

    NASA Astrophysics Data System (ADS)

    Abad, Carlos; Florek, Stefan; Becker-Ross, Helmut; Huang, Mao-Dong; Heinrich, Hans-Joachim; Recknagel, Sebastian; Vogl, Jochen; Jakubowski, Norbert; Panne, Ulrich

    2017-10-01

    Boron isotope amount ratios n(10B)/n(11B) have been determined by monitoring the absorption spectrum of boron monohydride (BH) in a graphite furnace using high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS). Bands (0 → 0) and (1 → 1) for the electronic transition X1Σ+ → A1Π were evaluated around wavelengths 433.1 nm and 437.1 nm respectively. Clean and free of memory effect molecular spectra of BH were recorded. In order to eliminate the memory effect of boron, a combination of 2% (v/v) hydrogen gas in argon and 1% trifluoromethane in argon, an acid solution of calcium chloride and mannitol as chemical modifiers was used. Partial least square regression (PLS) for analysis of samples and reference materials were applied. For this, a spectral library with different isotopes ratios for PLS regression was built. Results obtained around the 433.1 nm and 437.1 nm spectral regions are metrologically compatible with those reported by mass spectrometric methods. Moreover, for the evaluated region of 437 nm, an accuracy of 0.15‰ is obtained as the average deviation from the isotope reference materials. Expanded uncertainties with a coverage factor of k = 2 range between 0.15 and 0.44‰. This accuracy and precision are compatible with those obtained by mass spectrometry for boron isotope ratio measurements.

  7. Method for separating boron isotopes

    DOEpatents

    Rockwood, Stephen D.

    1978-01-01

    A method of separating boron isotopes .sup.10 B and .sup.11 B by laser-induced selective excitation and photodissociation of BCl.sub.3 molecules containing a particular boron isotope. The photodissociation products react with an appropriate chemical scavenger and the reaction products may readily be separated from undissociated BCl.sub.3, thus effecting the desired separation of the boron isotopes.

  8. Primitive boron isotope composition of the mantle.

    PubMed

    Chaussidon, M; Marty, B

    1995-07-21

    Boron isotope ratios are homogeneous in volcanic glasses of oceanic island basalts [-9.9 +/- 1.3 per mil, relative to standard NBS 951 (defined by the National Bureau of Standards)], whereas mid-oceanic ridge basalts (MORBs) and back-arc basin basalts (BABBs) show generally higher and more variable ratios. Melts that have assimilated even small amounts of altered basaltic crust show significant variations in the boron isotope ratios. Assimilation may thus account for the higher boron ratios of MORBs and BABBs. A budget of boron between mantle and crust implies that the primitive mantle had a boron isotope ratio of -10 +/- 2 per mil and that this ratio was not fractionated significantly during the differentiation of the mantle.

  9. 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.

  10. Boron isotopic compositions of some boron minerals

    SciTech Connect

    Oi, Takao; Musashi, Masaaki; Ossaka, Tomoko; Kakihana, Hidetake ); Nomura, Masao; Okamoto, Makoto )

    1989-12-01

    Boron minerals that have different structural formulae but are supposed to have the same geologic origin have been collected and analyzed for the {sup 11}B/{sup 10}B isotopic ratio. It has been reconfirmed that minerals of marine origin have higher {sup 11}B/{sup 10}B ratios than those of nonmarine origin. It has been found that the sequence of decreasing {sup 11}B/{sup 10}B values among the minerals with the same geologic origin is; borax, tincal, kernite (Na borates) > ulexite (Na/Ca borate) > colemanite, iyoite, meyerhofferite (Ca borates). This sequence is explainable on the basis of the difference in crystal structure among the minerals. That is, minerals with high BO{sub 3}/BO{sub 4} ratios, (the ratio of the number of the BO{sub 3} triangle units to the number of the BO{sub 4} tetrahedron units in the structural formula of a mineral) have higher {sup 11}B/{sup 10}B ratios.

  11. The Role of Boron-Chloride and Noble Gas Isotope Ratios in TVZ Geothermal Systems

    SciTech Connect

    Hulston, J.R.

    1995-01-01

    The model of the geothermal system in which deep circulating groundwater containing noble gases, at air saturated water concentrations, mixes with hot fluids of mantle origin at depth, is extended to include the effect of interaction of the ascending fluid with both solid and gaseous phases of basement (or other) rocks en route to the surface. It is demonstrated that this interaction is responsible for most of the CO{sub 2} in the Taupo Volcanic Zone (TVZ) geothermal systems. It is proposed that the modeling of this interaction might be accomplished by techniques similar to those used for the understanding of the oxygen isotope shift found in geothermal systems. The water rock interaction experiments of Ellis and Mahon (1964, 1967) provides some data on the kinetic rates for B and Cl dissolution from rocks likely to be encountered in the geothermal system, but further information on the behavior of B may be needed. If these problems can be overcome this modeling technique has promise for the estimation of the recharge of geothermal systems and hence the sustainability of these systems.

  12. Method of separating boron isotopes

    DOEpatents

    Jensen, R.J.; Thorne, J.M.; Cluff, C.L.

    1981-01-23

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)-dichloroborane as the feed material. The photolysis can readily by achieved with CO/sub 2/ laser radiation and using fluences significantly below those required to dissociate BCl/sub 3/.

  13. Method of separating boron isotopes

    DOEpatents

    Jensen, Reed J.; Thorne, James M.; Cluff, Coran L.; Hayes, John K.

    1984-01-01

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO.sub.2 laser radiation and using fluences significantly below those required to dissociate BCl.sub.3.

  14. Method of separating boron isotopes

    SciTech Connect

    Jensen, R.J.; Cluff, C.L.; Hayes, J.K.; Thorne, J.M.

    1984-05-08

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO/sub 2/ laser radiation and using fluences significantly below those required to dissociate BCl/sub 3/.

  15. (10)B/(11)B isotopic ratio and atomic composition of boron carbide: Determination by proton induced γ-ray emission and proton elastic backscattering spectrometry.

    PubMed

    Sunitha, Y; Kumar, Sanjiv

    2017-10-01

    The (10)B/(11)B isotopic ratio and the atomic composition of boron carbide, an important non-metallic ceramic, have been determined non-destructively by the particle induced γ-ray emission (PIGE) and elastic backscattering spectrometry (EBS) techniques with proton beams. The analysis has been performed on powder as well as sintered ceramics containing boron in natural or (10)B enriched composition. The PIGE technique, performed at a 4.0-4.2MeV proton energy, utilizes the (10)B(p,αγ)(7)Be, (10)B(p,p'γ)(10)B and (11)B(p, p'γ)(11)B nuclear reactions for (a) the isotopic analysis of boron and (b) the determination of total boron, and the (13)C(p,p'γ)(13)C nuclear reaction for the determination of carbon. The irradiation conditions were optimized by determining the thick targets yields of prompt γ-rays, characteristic of these reactions, in the 3.0-4.2MeV proton energy range. The quantitative analysis was performed by comparison with standards taking into account the attenuation of γ-rays in the specimens. The uncertainty in the determination of the (10)B/(11)B isotopic ratio and the B/C atomic ratio is about 2% and about 5% respectively. The analysis by EBS, on the other hand, involves the (10)B(p,p)(10)B, (11)B(p,p)(11)B and (12)C(p,p)(12)C elastic scatterings at the 2.0MeV proton energy. This method too yields satisfactory results. Between the two, PIGE is the method of choice for bulk analysis while EBS is useful in discerning compositional variations in surface regions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Fractionation of Boron Isotopes in Icelandic Hydrothermal Systems

    SciTech Connect

    Aggarwal, J.K.; Palmer, M.R.

    1995-01-01

    Boron isotope ratios have been determined in a variety of different geothermal waters from hydrothermal systems across Iceland. Isotope ratios from the high temperature meteoric water recharged systems reflect the isotope ratio of the host rocks without any apparent fractionation. Seawater recharged geothermal systems exhibit more positive {delta}{sup 11}B values than the meteoric water recharged geothermal systems. Water/rock ratios can be assessed from boron isotope ratios in the saline hydrothermal systems. Low temperature hydrothermal systems also exhibit more positive {delta}{sup 11}B than the high temperature systems, indicating fractionation of boron due to adsorption of the lighter isotope onto secondary minerals. Fractionation of boron in carbonate deposits may indicate the level of equilibrium attained within the systems.

  17. Evaluation of Ground-Water and Boron Sources by Use of Boron Stable-Isotope Ratios, Tritium, and Selected Water-Chemistry Constituents near Beverly Shores, Northwestern Indiana, 2004

    USGS Publications Warehouse

    Buszka, Paul M.; Fitzpatrick, John A.; Watson, Lee R.; Kay, Robert T.

    2007-01-01

    Concentrations of boron greater than the U.S. Environmental Protection Agency (USEPA) 900 ?g/L removal action level (RAL) standard were detected in water sampled by the USEPA in 2004 from three domestic wells near Beverly Shores, Indiana. The RAL regulates only human-affected concentrations of a constituent. A lack of well logs and screened depth information precluded identification of whether water from sampled wells, and their boron sources, were from human-affected or natural sources in the surficial aquifer, or associated with a previously defined natural, confined aquifer source of boron from the subtill or basal sand aquifers. A geochemically-based classification of the source of boron in ground water could potentially determine the similarity of boron to known sources or mixtures between known sources, or classify whether the relative age of the ground water predated the potential sources of contamination. The U.S. Geological Survey (USGS), in cooperation with the USEPA, investigated the use of a geochemical method that applied boron stable isotopes, and concentrations of boron, tritium, and other constituents to distinguish between natural and human-affected sources of boron in ground water and thereby determine if the RAL was applicable to the situation. Boron stable-isotope ratios and concentrations of boron in 17 ground-water samples and tritium concentrations in 9 ground-water samples collected in 2004 were used to identify geochemical differences between potential sources of boron in ground water near Beverly Shores, Indiana. Boron and d11B analyses for this investigation were made on unacidified samples to assure consistency of the result with unacidified analyses of d11B values from other investigations. Potential sources of boron included surficial-aquifer water affected by coal-combustion products (CCP) or domestic-wastewater, upward discharge of ground water from confined aquifers, and unaffected water from the surficial aquifer that was distant

  18. Intra-shell boron isotope ratios in the symbiont-bearing benthic foraminiferan Amphistegina lobifera: Implications for δ 11B vital effects and paleo-pH reconstructions

    NASA Astrophysics Data System (ADS)

    Rollion-Bard, C.; Erez, J.

    2010-03-01

    The boron isotope composition of marine carbonates is considered to be a seawater pH proxy. Nevertheless, the use of δ 11B has some limitations such as the knowledge of the fractionation factor ( α4-3) between boric acid and the borate ion and the amplitude of "vital effects" on this proxy that are not well constrained. Using secondary ion mass spectrometry (SIMS) we have examined the internal variability of the boron isotope ratio in 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. Intra-shell boron isotopes showed large variability with an upper limit value of ≈30‰. Our results suggest that the fractionation factor α4-3 of 0.97352 ( Klochko et al., 2006) is in better agreement with our experiments and with direct pH measurements in seawater vacuoles associated with the biomineralization process in these foraminifera. Despite the large variability of the skeletal pH values in each cultured specimen, it is possible to link the lowest calculated pH values to the experimental culture pH values while the upper pH limit is slightly below 9. This variability can be interpreted as follows: foraminifera variably increase the pH at the biomineralization site to about 9. This increase above ambient seawater pH leads to a range in δ 11B (Δ 11B) for each seawater pH. This Δ 11B is linearly correlated with the culture seawater pH with a slope of -13.1 per pH unit, and is independent of the fractionation factor α4-3, or the δ 11B sw through time. It may also be independent of the p KB (the dissociation constant of boric acid) value. Therefore, Δ 11B in foraminifera can potentially reconstruct paleo-pH of seawater.

  19. Boron isotope systematics of hydrothermal fluids from submarine hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Yamaoka, K.; Hong, E.; Ishikawa, T.; Gamo, T.; Kawahata, H.

    2013-12-01

    Boron is highly mobile in submarine hydrothermal systems and useful to trace the process of water-rock reaction. In this study, we measured the boron content and isotopic composition of vent fluids collected from arc-backarc hydrothermal systems in the western Pacific. In sediment-starved hydrothermal systems (Manus Basin, Suiyo Seamount, and Mariana Trough), the boron content and isotopic composition of vent fluids are dependent on type of host rock. The end member fluids from MORB-like basalt-hosted Vienna Woods in the Manus Basin showed low boron content and high δ11B value (0.53 mM, 29.8‰), while dacite-hosted PACMANUS and the Suiyo Seamount showed high boron contents and low δ11B values (1.45 and 1.52 mM, 13.6 and 18.5‰, respectively). The Alice Springs and Forecast Vent field in the Mariana Trough showed values intermediate between them (0.72 and 0.63 mM, 19.9 and 24.0‰, respectively), reflecting reaction of seawater and basalt influenced by slab material. In phase separated hydrothermal systems (North Fiji Basin), boron content and isotopic composition of vent fluids (0.44-0.56 mM, 34.5-35.9‰) were similar to those in the Vienna Woods. Considering little fractionation of boron and boron isotope during phase separation demonstrated by the previous experimental studies, it is suggested that the host rock in the North Fiji Basin is MORB-like basalt. In sediment-hosted hydrothermal system (Okinawa Trough), the reaction with boron-enriched sediment following seawater-rock reaction resulted in significantly high boron contents and low δ11B values of vent fluids (4.4-5.9 mM, 1.5-2.6‰). The water-sediment ratio was estimated to be ~2. In spite of the different geological settings, the end member fuids from all vent fields are enriched in B relative to seawater (0.41 mM, 39.6‰) and the δ11B values are inversely propotional to the boron concentrations. It suggests that boron isotopic composition of vent fluid predominantly depends on the amount of

  20. Separation and Analysis of Boron Isotope in High Plant by Thermal Ionization Mass Spectrometry

    PubMed Central

    Xu, Qingcai; Dong, Yuliang; Zhu, Huayu; Sun, Aide

    2015-01-01

    Knowledge of boron and its isotope in plants is useful to better understand the transposition and translocation of boron within plant, the geochemical behavior in the interface between soil and plant, and the biogeochemical cycle of boron. It is critical to develop a useful method to separate boron from the plant for the geochemical application of boron and its isotope. A method was developed for the extraction of boron in plant sample, whose isotope was determined by thermal ionization mass spectrometry. The results indicated that this method of dry ashing coupled with two-step ion-exchange chromatography is powerful for the separation of boron in plant sample with large amounts of organic matters completely. The ratios of boron isotope composition in those plant tissue samples ranged from −19.45‰ to +28.13‰ (total range: 47.58‰) with a mean value of 2.61 ± 11.76‰ SD. The stem and root isotopic compositions were lower than those in flower and leaf. The molecular mechanism of boron isotope may be responsible for the observed variation of boron isotopic composition and are considered as a useful tool for the better understanding of boron cycling process in the environment and for the signature of living systems. PMID:26819618

  1. New Carbonate Standard Reference Materials for Boron Isotope Geochemistry

    NASA Astrophysics Data System (ADS)

    Stewart, J.; Christopher, S. J.; Day, R. D.

    2015-12-01

    The isotopic composition of boron (δ11B) in marine carbonates is well established as a proxy for past ocean pH. Yet, before palaeoceanographic interpretation can be made, rigorous assessment of analytical uncertainty of δ11B data is required; particularly in light of recent interlaboratory comparison studies that reported significant measurement disagreement between laboratories [1]. Well characterised boron standard reference materials (SRMs) in a carbonate matrix are needed to assess the accuracy and precision of carbonate δ11B measurements throughout the entire procedural chemistry; from sample cleaning, to ionic separation of boron from the carbonate matrix, and final δ11B measurement by multi-collector inductively coupled plasma mass spectrometry. To date only two carbonate reference materials exist that have been value-assigned by the boron isotope measurement community [2]; JCp-1 (porites coral) and JCt-1 (Giant Clam) [3]. The National Institute of Standards and Technology (NIST) will supplement these existing standards with new solution based inorganic carbonate boron SRMs that replicate typical foraminiferal and coral B/Ca ratios and δ11B values. These new SRMs will not only ensure quality control of full procedural chemistry between laboratories, but have the added benefits of being both in abundant supply and free from any restrictions associated with shipment of biogenic samples derived from protected species. Here we present in-house δ11B measurements of these new boron carbonate SRM solutions. These preliminary data will feed into an interlaboratory comparison study to establish certified values for these new NIST SRMs. 1. Foster, G.L., et al., Chemical Geology, 2013. 358(0): p. 1-14. 2. Gutjahr, M., et al., Boron Isotope Intercomparison Project (BIIP): Development of a new carbonate standard for stable isotopic analyses. Geophysical Research Abstracts, EGU General Assembly 2014, 2014. 16(EGU2014-5028-1). 3. Inoue, M., et al., Geostandards and

  2. The geochemical cycle of boron: Constraints from boron isotope partitioning experiments between mica and fluid

    NASA Astrophysics Data System (ADS)

    Wunder, Bernd; Meixner, Anette; Romer, Rolf L.; Wirth, Richard; Heinrich, Wilhelm

    2005-10-01

    The fractionation of boron isotopes between synthetic boromuscovite and fluid was experimentally determined at 3.0 GPa/500 °C and 3.0 GPa/700 °C. For near-neutral fluids Δ 11B (mica-fluid) = δ 11B (mica) - δ 11B (fluid) is - 10.9 ± 1.3‰ at 500 °C, and - 6.5 ± 0.4‰ at 700 °C. This supports earlier assumptions that the main fractionation effect is due to the change from trigonal coordination of boron in neutral fluids to tetrahedrally coordinated boron in micas, clays and melts. The T-dependence of this effect is approximated by the equation Δ 11B (mica,clay,melt-neutral fluid) = - 10.69 · (1000/ T [K]) + 3.88; R2 = 0.992, valid from 25 °C for fluid-clay up to about 1000 °C for fluid-silicate melt. Experiments at 0.4 GPa that used strongly basic fluids produced significantly lower fractionations with Δ 11B (mica-fluid) of - 7.4 ± 1.0‰ at 400 °C, and - 4.8 ± 1.0‰ at 500 °C, showing the reduced fractionation effect when large amounts of boron in basic fluids are tetrahedrally coordinated. Field studies have shown that boron concentrations and 11B/ 10B-ratios in volcanic arcs systematically decrease across the arc with increasing distance from the trench, thus reflecting the thermal structure of the subducting slab. Our experiments show that the boron isotopic signature in volcanic arcs probably results from continuous dehydration of micas along a distinct P- T range. Continuous slab dehydration and boron transport via fluid into the mantle wedge is responsible for the boron isotopic signature in volcanic arcs.

  3. Boron isotope fractionation in magma via crustal carbonate dissolution

    PubMed Central

    Deegan, Frances M.; Troll, Valentin R.; Whitehouse, Martin J.; Jolis, Ester M.; Freda, Carmela

    2016-01-01

    Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to −41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle. PMID:27488228

  4. Boron isotope fractionation in magma via crustal carbonate dissolution.

    PubMed

    Deegan, Frances M; Troll, Valentin R; Whitehouse, Martin J; Jolis, Ester M; Freda, Carmela

    2016-08-04

    Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ(11)B values down to -41.5‰, reflecting preferential partitioning of (10)B into the assimilating melt. Loss of (11)B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports (11)B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ(11)B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

  5. Hydrochemistry and boron isotopes as natural tracers in the study of groundwaters from North Chianan Plain, Taiwan.

    PubMed

    Lu, Hsueh-Yu

    2014-01-01

    In this paper, hydrochemistry and boron isotopes are successfully applied to elucidate hydrogeological processes by the use of natural tracers. The hydrochemical analysis identifies four end-members in the hydrochemical evolution of groundwater from the North Chianan plain groundwater district. A few groundwater contain extraordinary chlorine concentrations of up to 48,000 mg l(-1). However, the hydrochemistry of groundwater only reveals that high saline water is a dominant factor in groundwater hydrochemistry. It is thought that these groundwater experienced precipitation of carbonates during seawater evaporation that did not involve the precipitation of gypsum. Boron isotopes are very efficient tracers in determining the source of salinisation. The boron isotopes reveal the results of mixing of evaporated seawater and water-sediment interaction. In general, the boron isotope ratio of the groundwater is controlled by a two-end-member mixing system, which is composed of evaporated seawater (isotopically heavy) and fresh surface water (isotopically light). Due to a long lagoonal period in the coastal plain, the groundwaters in the downstream area generally have high Cl/B ratios and relatively heavy boron isotope ratios while those in the upstream area are composed of low Cl/B and light boron isotopes. However, there is not a resolvable mixing trend between the Cl/B ratio and the isotopic composition of boron. It is probably obscured by a highly variable boron isotope ratio in fresh surface water and through fractionation associated with water-rock interaction. Both factors would decrease the boron isotope ratio but one effect cannot be distinguished from the other.

  6. Boron and strontium isotope ratios and major/trace elements concentrations in tea leaves at four major tea growing gardens in Taiwan.

    PubMed

    Chang, Cheng-Ta; You, Chen-Feng; Aggarwal, Suresh Kumar; Chung, Chuan-Hsiung; Chao, Hung-Chun; Liu, Hou-Chun

    2016-06-01

    Isotopic compositions of B and Sr in rocks and sediments can be used as tracers for plant provincial sources. This study aims to test whether tea leaf origin can be discriminated using (10)B/(11)B and Sr isotopic composition data, along with concentrations of major/trace elements, in tea specimens collected from major plantation gardens in Taiwan. The tea leaves were digested by microwave and analyzed by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). The data showed significant variations in (87)Sr/(86)Sr ratios (from 0.70482 to 0.71462), which reflect changes in soil, groundwater or irrigation conditions. The most radiogenic tea leaves were found at the Taitung garden and the least radiogenic ones were from the Hualien garden. The δ (11)B was found to change appreciably (δ (11)B = 0.38-23.73 ‰) which could be due to fertilizers. The maximum δ (11)B was also observed in tea samples from the Hualien garden. Principal component analysis combining (87)Sr/(86)Sr, δ (11)B and major/trace elements results successfully discriminated different sources of major tea gardens in Taiwan, except the Hualien gardens, and this may be due to rather complicated local geological settings.

  7. Boron Isotopes in Modern and Cenozoic Scleractinian Fossil Corals

    NASA Astrophysics Data System (ADS)

    Gothmann, A.; Bender, M. L.; Adkins, J. F.

    2016-12-01

    Recent measurements of boron isotopes in modern coral support the hypothesis that coral biologically up-regulate the pH of the fluid from which they calcify to facilitate skeletal mineralization [1]. While this evidence of biological pH adjustment provides important insight into the mechanism by which coral make their skeletons, it also complicates the use of coral boron isotopes as a paleoseawater pH proxy. We measured boron isotopes in 11 modern and well preserved fossil corals using Secondary Ion Mass Spectrometry to characterize fine-scale ( 30 µm) patterns of δ11B variability. In addition to δ11B, we measured B/Ca, Mg/Ca, Sr/Ca, and Mn/Ca ratios in order to compare isotopes with element/Ca variability and monitor for diagenetic alteration. We find that in different species of modern and well preserved fossil coral, the measured range of δ11B varies from 5 to 15 ‰. Also, while corals of similar geologic age have similar average δ11B compositions, at the scale of our measurements they do not appear to share a consistent pattern of minimum δ11B, maximum δ11B, or range in δ11B. The δ11B of fossil corals increases by 7 ‰ between the Early Cenozoic and today. While the general pattern of coral δ11B change is similar to the pattern found in foraminifera-based δ11B records [e.g., 2], the magnitude of the coral change is approximately 2-3 times as large as changes inferred from foraminifera. Although it is not possible to separate the influence of changing seawater pH and changing δ11Bseawater on fossil coral boron isotope compositions, the record can be explained by a combination of lower seawater pH and lower seawater δ11B during the the Early Cenozoic. Our coral results suggest an Early Cenozoic δ11Bseawater composition that is much lower than inferred from other approaches, and similar to Early Cenozoic δ11Bseawater as inferred from brine inclusions in halite [3]. [1.] McCulloch, M.T., Trotter, J., Montagna, P., Falter, J., Dunbar, R., Freiwald

  8. Isotopic ratios in planetary atmospheres.

    PubMed

    de Bergh, C

    1995-03-01

    Recent progress on measurements of isotopic ratios in planetary or satellite atmospheres include measurements of the D/H ratio in the methane of Uranus, Neptune and Titan and in the water of Mars and Venus. Implications of these measurements on our understanding of the formation and evolution of the planets and satellite are discussed. Our current knowledge of the carbon, nitrogen and oxygen isotopic ratios in the atmospheres of these planets, as well as on Jupiter and Saturn, is also reviewed. We finally show what progress can be expected in the very near future due to some new ground-based instrumentation particularly well suited to such studies, and to forthcoming space missions.

  9. Outside the pH box: Boron isotopes in synthetic calcite precipitated under varying solution chemistry

    NASA Astrophysics Data System (ADS)

    Farmer, J. R.; Uchikawa, J.; Penman, D. E.; Hoenisch, B.; Zeebe, R. E.

    2015-12-01

    Boron isotopic measurements (δ11B) in marine carbonates are a powerful tool for reconstructing past ocean carbon chemistry and the carbon cycle. Boron systematics in marine carbonates are rooted in the equilibrium dissociation of dissolved boron in seawater, but existing evidence from biogenic carbonates (corals, planktic and benthic foraminifers) suggests somewhat variable controls on boron concentration and δ11B. Synthetic precipitation experiments provide an opportunity to study boron systematics without biological interference, and recent studies (e.g., Uchikawa et al., 2015, GCA v150, 171-191) suggest that boron incorporation (measured as B/Ca ratios) into synthetic carbonates varies both with the elemental composition of experimental seawater and precipitation rate. Here we extend the geochemical characterization of synthetic calcite by investigating the influences of changing solution chemistry (pH, [Ca2+], [DIC] and [B]) and precipitation rate on their boron isotopic composition. Our results will be evaluated in the context of carbonate precipitation rates, modes of boron incorporation, and changing seawater chemistry through geologic time.

  10. A reconnaissance of the boron isotopic composition of tourmaline

    SciTech Connect

    Swihart, G.H.; Moore, P.B. )

    1989-04-01

    A preliminary investigation of the boron isotopic composition of tourmaline from some boron-rich associations has been made. The results for tourmaline from metasedimentary paragneisses (n = 12) range from {delta}{sup 11}B = {minus}22 to +22 per mil. These data mainly fall between the boron isotopic compositions of normal marine sediments with {delta}{sup 11}B = {minus}2 to +5 per mil and seawater with {delta}{sup 11}B = +39.5 per mil. Tourmaline samples from granitic pegmatites (n = 6), on the other hand, range from {delta}{sup 11}B = {minus}12 to {minus}5 per mil. The data provide a rudimentary indication of the range of boron isotopic variation in tourmaline, some of the processes leading to this range, and some possible geochemical tracer applications.

  11. Boron isotopic composition of tourmaline from massive sulfide deposits and tourmalinites

    USGS Publications Warehouse

    Palmer, M.R.; Slack, J.F.

    1989-01-01

    Boron isotope ratios (11B/10B) have been measured on 60 tourmaline separates from over 40 massive sulfide deposits and tourmalinites from a variety of geologic and tectonic settings. The coverage of these localities is global (5 continents) and includes the giant ore bodies at Kidd Creek and Sullivan (Canada), Broken Hill (Australia), and Ducktown (USA). Overall, the tourmalines display a wide range in ??11B values from -22.8 to +18.3??? Possible controls over the boron isotopic composition of the tourmalines include: 1) composition of the boron source, 2) regional metamorphism, 3) water/rock ratios, 4) seawater entrainment, 5) temperature of formation, and 6) secular variations in seawater ??11B. The most significant control appears to be the composition of the boron source, particularly the nature of footwall lithologies; variations in water/ rock ratios and seawater entrainment are of secondary importance. The boron isotope values seem especially sensitive to the presence of evaporites (marine and non-marine) and carbonates in source rocks to the massive sulfide deposits and tourmalinites. ?? 1989 Springer-Verlag.

  12. Boron, Thorium and Oxygen Isotopes in Icelandic Tephra

    NASA Astrophysics Data System (ADS)

    Rose-Koga, E. F.; Sigmarsson, O.

    2006-12-01

    Important Th-isotope variations in silicic rocks from Iceland have been interpreted in terms of partial melting of a metabasic crust. This hypothesis was tested by boron systematics, since both the B-isotope ratios and their concentration are significantly different in the altered oceanic crust and the underlying mantle. Here we present new boron isotope compositions and concentrations measured by ion microprobe (3f, Nancy, France) on Holocene tephra samples from 6 Icelandic volcanoes. The B concentrations vary by more than a factor 20, from 1.48±0.03 to 36.38±4.46 ppm in basaltic tholeiite and trachytes, respectively. A large range is also observed for B isotope compositions, between - 9.8±2.0 in a trachyte to +7.6±2.6‰ in a subalkaline rhyolite from Askja volcano. Furthermore, the δ^{11}B correlates positively with Th/B (0.26 < Th/B < 2.90) and negatively with 230Th/232Th (0.940 < (230Th/232Th) < 1.067) and with δ18O (-0.2 to +5.3‰). The variations of B isotope compositions in the Icelandic tephra and the correlations with both δ18O and (230Th/232Th) strongly support the crustal melting model for most Icelandic rhyolites. In fact, the co-variation is interpreted as a mixing between mantle derived basalts and crustal melts derived from the anatexis of hydrothermally altered basaltic crust. The highest δ^{11}B (+7.6±2.6 and +7.1±2.1‰) measured in rhyolites from the rift-related Askja and Krafla volcanoes represent the B-isotope composition for the altered Icelandic crust. These values are indeed well within the range of values proposed for altered oceanic crust (between +0.1 and +9.2‰, Spivack and Edmond, 1987 ; +3.4±1.1‰, Smith et al., 1995). In contrast, the lowest δ^{11}B values (-9.8 to -5.7‰) are observed in samples with the highest δ18O (+4.95 to +5.30‰) and (230Th/232Th; 0.990 to 1.067) corresponding to a "normal-mantle" signature (δ^{11}B =- 9.9±1.3‰; Chaussidon and Marty, 1995).

  13. Isotopic Enrichment of Boron in the Sputtering of Boron Nitride with Xenon Ions

    NASA Technical Reports Server (NTRS)

    Ray, P. K.; Shutthanandan, V.

    1998-01-01

    An experimental study is described to measure the isotopic enrichment of boron. Xenon ions from 100 eV to 1.5 keV were used to sputter a boron nitride target. An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 microA/sq cm. Xenon ions impinged on the target surface at 50 deg angle to the surface normal. Since boron nitride is an insulator, a flood electron gun was used in our experiments to neutralize the positive charge buildup on the target surface. The sputtered secondary ions of boron were detected by a quadrupole mass spectrometer. The spectrometer entrance aperture was located perpendicular to the ion beam direction and 10 mm away from the target surface. The secondary ion flux was observed to be enriched in the heavy isotopes at lower ion energies. The proportion of heavy isotopes in the sputtered secondary ion flux was found to decrease with increasing primary ion energy from 100 to 350 eV. Beyond 350 eV, light isotopes were sputtered preferentially. The light isotope enrichment factor was observed to reach an asymptotic value of 1.27 at 1.5 keV. This trend is similar to that of the isotopic enrichment observed earlier when copper was sputtered with xenon ions in the same energy range.

  14. Isotopic Enrichment of Boron in the Sputtering of Boron Nitride with Xenon Ions

    NASA Technical Reports Server (NTRS)

    Ray, P. K.; Shutthanandan, V.

    1998-01-01

    An experimental study is described to measure the isotopic enrichment of boron. Xenon ions from 100 eV to 1.5 keV were used to sputter a boron nitride target. An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 microA/sq cm. Xenon ions impinged on the target surface at 50 deg angle to the surface normal. Since boron nitride is an insulator, a flood electron gun was used in our experiments to neutralize the positive charge buildup on the target surface. The sputtered secondary ions of boron were detected by a quadrupole mass spectrometer. The spectrometer entrance aperture was located perpendicular to the ion beam direction and 10 mm away from the target surface. The secondary ion flux was observed to be enriched in the heavy isotopes at lower ion energies. The proportion of heavy isotopes in the sputtered secondary ion flux was found to decrease with increasing primary ion energy from 100 to 350 eV. Beyond 350 eV, light isotopes were sputtered preferentially. The light isotope enrichment factor was observed to reach an asymptotic value of 1.27 at 1.5 keV. This trend is similar to that of the isotopic enrichment observed earlier when copper was sputtered with xenon ions in the same energy range.

  15. Re-calculating the pH record from boron isotopic composition of biogenic carbonates

    NASA Astrophysics Data System (ADS)

    Paris, G.; Gaillardet, J.; Louvat, P.

    2010-12-01

    paleo-pH reconstruction over the Cenozoic: Chemical Geology, v. 190, p. 123-140. Paris, G., Gaillardet, J., and Louvat, P. (2010), Geological record of boron isotopes in marine evaporites: Geology, v. in press. Pearson, P., N., and Palmer, M., R. (2000), Atmospheric carbon dioxide concentrations over the past 60 million years: Nature, v. 406, p. 695-699. Pearson, P.N., Foster, G.L., and Wade, B.S. (2009), Atmospheric carbon dioxide through the Eocene-Oligocene climate transition: Nature, v. 461, p. 1110-1113. Seki, O., et al. (2010), Alkenone and boron-based Pliocene pCO2 records: Earth and Planetary Science Letters, v. 292, p. 201-211. Spivack, A.J., You, C.F., and Smith, J., (1993), Foraminiferal boron isotope ratios as a proxy for surface ocean pH over the past 21 Myr: Nature, v. 363, p. 149-151. Vengosh, A., et al. 1991, Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates: Geochimica et Cosmochimica Acta, v. 55, p. 2901-2910.

  16. Short-term coral bleaching is not recorded by skeletal boron isotopes.

    PubMed

    Schoepf, Verena; McCulloch, Malcolm T; Warner, Mark E; Levas, Stephen J; Matsui, Yohei; Aschaffenburg, Matthew D; Grottoli, Andréa G

    2014-01-01

    Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of

  17. Short-Term Coral Bleaching Is Not Recorded by Skeletal Boron Isotopes

    PubMed Central

    Schoepf, Verena; McCulloch, Malcolm T.; Warner, Mark E.; Levas, Stephen J.; Matsui, Yohei; Aschaffenburg, Matthew D.; Grottoli, Andréa G.

    2014-01-01

    Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of

  18. Separation of the isotopes of boron by chemical exchange reactions

    DOEpatents

    McCandless, Frank P.; Herbst, Ronald S.

    1995-01-01

    The isotopes of boron, .sup.10 B and .sup.11 B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF.sub.3 and a liquid BF.sub.3 . donor molecular addition complex formed between BF.sub.3 gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone.

  19. Separation of the isotopes of boron by chemical exchange reactions

    DOEpatents

    McCandless, F.P.; Herbst, R.S.

    1995-05-30

    The isotopes of boron, {sup 10}B and {sup 11}B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF{sub 3} and a liquid BF{sub 3} donor molecular addition complex formed between BF{sub 3} gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone. 1 Fig.

  20. Reconstructing Ocean pH with Boron Isotopes in Foraminifera

    NASA Astrophysics Data System (ADS)

    Foster, Gavin L.; Rae, James W. B.

    2016-06-01

    In order to better understand the effect of CO2 on the Earth system in the future, geologists may look to CO2-induced environmental change in Earth's past. Here we describe how CO2 can be reconstructed using the boron isotopic composition (δ11B) of marine calcium carbonate. We review the chemical principles that underlie the proxy, summarize the available calibration data, and detail how boron isotopes can be used to estimate ocean pH and ultimately atmospheric CO2 in the past. δ11B in a variety of marine carbonates shows a coherent relationship with seawater pH, in broad agreement with simple models for this proxy. Offsets between measured and predicted δ11B may in part be explained by physiological influences, though the exact mechanisms of boron incorporation into carbonate remain unknown. Despite these uncertainties, we demonstrate that δ11B may provide crucial constraints on past ocean acidification and atmospheric CO2.

  1. Experimental measurement of boron isotope fractionation in seawater

    NASA Astrophysics Data System (ADS)

    Klochko, Kateryna; Kaufman, Alan J.; Yao, Wengsheng; Byrne, Robert H.; Tossell, John A.

    2006-08-01

    The boron isotopic composition of marine carbonates is considered to be a tracer of seawater pH. Use of this proxy benefits from an intimate understanding of chemical kinetics and thermodynamic isotope exchange reactions between the two dominant boron-bearing species in seawater: boric acid B(OH) 3 and borate ion B(OH) 4-. However, because of our inability to quantitatively separate these species in solution, the degree of boron isotope exchange has only been known through theoretical estimates. In this study, we present results of a spectrophotometric procedure wherein the boron isotope equilibrium constant ( 11-10KB) is determined empirically from the difference in the dissociation constants of 11B(OH) 3 and 10B(OH) 3 in pure water, 0.6 mol kg - 1 H 2O KCl and artificial seawater. Within experimental uncertainty, our results show no dependence of 11-10KB on temperature, but 11-10KB at 25 °C in pure water was statistically different than results obtained in solutions at high ionic strength. 11-10KB of the seawater ( S = 35, B T = 0.01 mol kg - 1 H 2O) at 25 °C is 1.0272 ± 0.0006. This result is significantly larger than the theoretical value used in numerous paleo-pH studies ( 11-10KB = 1.0194).

  2. Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates

    SciTech Connect

    Vengosh, A. Hebrew Univ., Jerusalem ); Chivas, A.R.; McCulloch, M.T. ); Kolodny, Y.; Starinsky, A. )

    1991-10-01

    The abundances and isotopic composition of boron in modern, biogenic calcareous skeletons from the Gulf of Elat, Israel, the Great Barrier Reef, Australia, and in deep-sea sediments have been examined by negative thermal-ionization mass spectrometry. The selected species (Foraminifera, Pteropoda, corals, Gastropoda, and Pelecypoda) yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80 ppm in corals. The variations of {delta}{sup 11}B may be controlled by isotopic exchange of boron species in which {sup 10}B is preferentially partitioned into the tetrahedral species, and coprecipitation of different proportions of trigonal and tetrahedral species in the calcium carbonates. The B content and {delta}{sup 11}B values of deep-sea sediments, Foraminifera tests, and corals are used to estimate the global oceanic sink of elemental boron by calcium carbonate deposition. As a result of enrichment of B in corals, a substantially higher biogenic sink of 6.4 {plus minus} 0.9 {times} 10{sup 10} g/yr is calculated for carbonates. This is only slightly lower than the sink for desorbable B in marine sediments (10 {times} 10{sup 10} g/yr) and approximately half that of altered oceanic crust (14 {times} 10{sup 10} g/yr). Thus, carbonates are an important sink for B in the oceans being {approximately}20% of the total sinks. The preferential incorporation of {sup 10}B into calcium carbonate results in oceanic {sup 11}B-enrichment, estimated as 1.2 {plus minus} 0.3 {times} 10{sup 12} per mil {center dot} g/yr. The boron-isotope composition of authigenic, well-preserved carbonate skeletons may provide a useful tool to record secular boron-isotope variations in seawater at various times in the geological record.

  3. Boron isotope exchange in a heterogeneous boron-boron fluoride system

    SciTech Connect

    Begak, O.Yu.; Fedorov, V.V.

    1988-11-01

    Studies have been made on exchange between /sup 10/B and /sup 11/B in heterogeneous systems containing finely divided amorphous boron and BF/sub 3/ gas. The kinetic and thermodynamic parameters have been examined. The self-diffusion coefficient for boron in amorphous boron has been determined at 973-1273 K.

  4. Boron isotopes at the Shale Hills Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Gaillardet, J.; Noireaux, J.; Sullivan, P. L.; Steinhoefel, G.; Louvat, P.; Brantley, S. L.

    2015-12-01

    The Shale Hills Critical Zone Observatory is a Northern Appalachian catchment site where a series of geochemical tracers have been applied in order to build a multi-isotope integrative model (referred to as "CZ-tope"). The catchment is small (8ha) and relief is about 30 m. It receives about 107 cm of precipitation per year. Mean annual temperature is 10°C. Shales Hills observatory has a relatively simple lithology consisting of organic-poor shales rich in illite and relatively infrequent interbedded carbonates and sandstones. Vegetation consists mainly of deciduous trees. Soil thickness ranges from 0.3 m at the ridgetop to 3 m in the valley floor. Following the CZ-tope concept, boron isotopes were analysed in the main geochemical reservoirs of the SH catchment (stream, vegetation, soil pore waters, solid phases, groundwaters). Measurements were conducted using MC-ICPMS and a direct injection system after a chemical procedure aiming at isolating boron from geological matrix. Results are expressed as δ11B. Error bars are better than 0.5‰ Boron isotopes in Shale Hills catchment show a large range of variation. While bedrock values are within a narrow range around -5‰, stream waters range between 10‰ and 15‰, and exhibit temporal variations. This very strong 11B enrichment is also observed in the vegetation, groundwater and rainwater reservoirs but with a much larger range of variation. The input of 11B-enriched water by precipitation is contributing to the B budget at the catchment outlet but cannot explain all the 11B enrichment with respect to parent bedrock. The solid phases collected along two different soil profiles and as suspended sediments in the stream are close to the bedrock value or slightly 10B-enriched. The most important conclusion from boron isotope investigation at Shale Hills CZO is that a simple mass budget is not able to reconcile the strong 11B-enrichment measured in the water phases and vegetation with the isotopic signature of the

  5. 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.

  6. Boron isotope determinations in waters and other geological materials: analytical techniques and inter-calibration of measurements.

    PubMed

    Tonarini, Sonia; Pennisi, Maddalena; Gonfiantini, Roberto

    2009-06-01

    The (11)B/(10)B ratio exhibits wide variations in nature; thus, boron isotopes have found numerous applications in geochemistry, hydrology, and environmental studies. The main analytical techniques used are as follows: positive thermal ionisation mass spectrometry is the most precise (about 0.2 per thousand of the boron isotope ratio), but requires complex and laborious sample preparation; negative thermal ionisation mass spectrometry is less precise (about 0.5 per thousand), but rapid and suitable for water samples, whereas total evaporation-NTIMS allows for identification of the precise boron isotope composition of marine carbonates. It is expected that multi-collection system inductively coupled plasma mass spectrometry (MC-ICPMS) will eventually combine high precision with simple analytical procedures. Secondary ion mass spectrometry and laser ablation (LA)-MC-ICPMS allow in situ determinations on solid samples, but require the availability of calibration materials which are chemically and mineralogically similar to samples. These features of boron isotope measurement techniques were confirmed by the results of the first inter-laboratory comparison of measurements, organised by the Istituto di Geoscienze e Georisorse in Pisa. Finally, two examples of boron isotope applications in groundwater investigations are reported.

  7. Boron Isotopes in Diatoms: a Proxy for pH?

    NASA Astrophysics Data System (ADS)

    Donald, H.; Foster, G. L.; Poulton, A. J.; Moore, C. M.; Swann, G. E. A.; Hendry, K. R.

    2016-12-01

    High latitudes are important regions to consider in terms of ocean acidification, as they are climatically sensitive regions where the greenhouse gas CO2 is exchanged between the ocean and atmosphere. In theory, an improved understanding of these regions could be achieved using the boron isotope palaeo-pH proxy, in which CaCO3-based organisms including foraminifera are traditionally measured. The Southern Ocean is of particular interest in the global carbon cycle, however, foraminifera are scarce in sediments from this region. In contrast, siliceous diatoms are a dominant group of microfossils found within sediments, but as yet, the boron isotope-pH proxy has not been extended to opal. This is the major goal of the current study. Diatoms construct their frustules from biogenic silica by polymerising Si(OH)4, and boron content of these frustules, previously investigated by LA-ICP-MS (Mejía et al. 2013), is around 5-10 ppm. Here, current solution MC-ICP-MS methods used to measure boron isotopes in calcifying organisms have been adapted and developed for use with diatom opal. Preliminary results for sediment diatoms from the onset of major Northern Hemisphere glaciation will be presented (subarctic Northwest Pacific ODP site 882), as well as results for the cultured diatom species Thalassiosira weissflogii grown at varied pCO2. In light of these results, we will speculate on the nature of boron incorporation into diatom opal and its potential as an archive for palaeo-pH reconstructions.

  8. Development of particle induced gamma-ray emission methods for nondestructive determination of isotopic composition of boron and its total concentration in natural and enriched samples.

    PubMed

    Chhillar, Sumit; Acharya, Raghunath; Sodaye, Suparna; Pujari, Pradeep K

    2014-11-18

    We report simple particle induced gamma-ray emission (PIGE) methods using a 4 MeV proton beam for simultaneous and nondestructive determination of the isotopic composition of boron ((10)B/(11)B atom ratio) and total boron concentrations in various solid samples with natural isotopic composition and enriched with (10)B. It involves measurement of prompt gamma-rays at 429, 718, and 2125 keV from (10)B(p,αγ)(7)Be, (10)B(p, p'γ)(10)B, and (11)B(p, p'γ)(11)B reactions, respectively. The isotopic composition of boron in natural and enriched samples was determined by comparing peak area ratios corresponding to (10)B and (11)B of samples to natural boric acid standard. An in situ current normalized PIGE method, using F or Al, was standardized for total B concentration determination. The methods were validated by analyzing stoichiometric boron compounds and applied to samples such as boron carbide, boric acid, carborane, and borosilicate glass. Isotopic compositions of boron in the range of 0.247-2.0 corresponding to (10)B in the range of 19.8-67.0 atom % and total B concentrations in the range of 5-78 wt % were determined. It has been demonstrated that PIGE offers a simple and alternate method for total boron as well as isotopic composition determination in boron based solid samples, including neutron absorbers that are important in nuclear technology.

  9. Boron and strontium isotopic characterization of coal combustion residuals: validation of new environmental tracers.

    PubMed

    Ruhl, Laura S; Dwyer, Gary S; Hsu-Kim, Heileen; Hower, James C; Vengosh, Avner

    2014-12-16

    In the U.S., coal fired power plants produce over 136 million tons of coal combustion residuals (CCRs) annually. CCRs are enriched in toxic elements, and their leachates can have significant impacts on water quality. Here we report the boron and strontium isotopic ratios of leaching experiments on CCRs from a variety of coal sources (Appalachian, Illinois, and Powder River Basins). CCR leachates had a mostly negative δ(11)B, ranging from -17.6 to +6.3‰, and (87)Sr/(86)Sr ranging from 0.70975 to 0.71251. Additionally, we utilized these isotopic ratios for tracing CCR contaminants in different environments: (1) the 2008 Tennessee Valley Authority (TVA) coal ash spill affected waters; (2) CCR effluents from power plants in Tennessee and North Carolina; (3) lakes and rivers affected by CCR effluents in North Carolina; and (4) porewater extracted from sediments in lakes affected by CCRs. The boron isotopes measured in these environments had a distinctive negative δ(11)B signature relative to background waters. In contrast (87)Sr/(86)Sr ratios in CCRs were not always exclusively different from background, limiting their use as a CCR tracer. This investigation demonstrates the validity of the combined geochemical and isotopic approach as a unique and practical identification method for delineating and evaluating the environmental impact of CCRs.

  10. The boron isotope geochemistry of the neogene borate deposits of western Turkey

    NASA Astrophysics Data System (ADS)

    Palmer, M. R.; Helvaci, C.

    1997-08-01

    We have analyzed the boron isotope composition of 80 borate minerals (major minerals: borax, colemanite, and ulexite; minor minerals: veatchite-A, tunellite, kernite, terrugite, probertite, meyer-hofferite, inderite, inyoite, hydroboracite, howlite, and pandermite) from the main deposits (Kirka, Bigadiç, and Emet) and two smaller deposits (Kestelek and Sultançayir) in the western Turkish borate deposits. Forty-three samples were also analysed for their Sr isotope composition. The data span a wide range in δ11B values from -1.6%o to -25.3%o. The δ 11B values of the main borate minerals are largely controlled by their mineralogy and the pH of the brines from which they precipitated. An inverse correlation between the average δ 11B and 87Sr/86Sr ratios of colemanite in the different deposits suggests there is some variation in the sources of boron and Sr to the deposits. Emet has the highest contribution from aluminosilicates and Kirka the highest contribution from Eocene carbonates, with Bigadiç occupying an intermediate position. The δ11B values of the minor borate minerals distinguish between those which are primary precipitates from the original brines (or formed from primary borates without boron loss from the system) and those which formed from alteration of preexisting borate minerals with substantial loss of boron from the system.

  11. Boron and strontium isotope compositions of groundwater from the La Paz arid coastal aquifer, Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Mahlknecht, Jürgen; Rosner, Martin; Meixner, Anette

    2016-04-01

    In groundwater studies boron and strontium isotopic compositions can be used to identify natural and anthropogenic sources as well as processes related to groundwater recharge, flow and mixing. The La Paz arid costal aquifer in Baja California Sur, Mexico, is the most important source of drinking and irrigation water for La Paz area and suffers from anthropogenic contamination and intensive exploitation of the aquifer causing seawater intrusion and general groundwater abatement. The relatively un-radiogenic 87Sr/86Sr isotope ratios of the La Paz groundwater range in a narrow field between 0.7054 and 0.7062. In contrast to strontium the boron isotope composition displays a large variability between +27 and +55 permil d11B. The relatively low 87Sr/86Sr ratios of the La Paz groundwater highlight a significant contribution of strontium derived from local terrestrial sediments and igneous rocks with known 87Sr/86Sr ratios between 0.705 and 0.7035. The large variability of d11B values indicate that multiple sources and processes determine the boron isotope composition of La Paz groundwater. Rainwater (high d11B), seawater (~+40 permil) due to seawater intrusions, wastewater (low to medium d11B) and boron derived from the local geology (low to medium d11B) explain most of the observed groundwater d11B variability. However, d11B values higher than modern seawater point to significant boron isotope fractionation by preferential absorption of 10B onto clay minerals during the evolution of some groundwater samples. Due to low boron concentrations in rainwater a significant contribution of 11B-rich rainwater (>+40 permil) on the La Paz groundwater is unlikely.

  12. Boron isotope geochemistry during diagenesis. Part II. Applications to organic-rich sediments

    NASA Astrophysics Data System (ADS)

    Williams, Lynda B.; Hervig, Richard L.; Hutcheon, Ian

    2001-06-01

    The measured clay-water isotope fractionation for boron was applied to natural organic-rich sediments undergoing illitization. Two field areas were chosen that show illitization occurring over a range of temperatures (80-500°C). Samples representing diagenetic temperatures of illitization (80-200°C) are from the Gulf of Mexico sedimentary basin at 4 to 6-km depth in the Eocene Wilcox Fm and Jurassic Norphlet Fm. The higher temperatures of illitization (200-500°C) occur in a contact metamorphic aureole of the Cretaceous Pierre shale near Walsenburg, Colorado. Here the kinetics of the illitization reaction are more rapid than in a slowly subsiding sedimentary basin, but the chemical and mineralogical variations are minimized as complete illitization occurs over a small lateral distance in a single bentonite layer. These studies indicate that B-isotopes provide a more sensitive indicator of fluid variations in sedimentary basins than O-isotopes, and that B-isotope analyses of authigenic illite can be a valuable geochemical tracer of fluid/rock interactions. Boron isotope ratios in authigenic illite (pore filling) and muscovite (stylolites) from reservoir sandstones in the Gulf of Mexico are distinct from adjacent illitic mudstones, whereas the oxygen isotopic ratios show little variation. Fluids in equilibrium with the mudstones cannot precipitate the authigenic clays with higher δ 11B values measured in the hydrocarbon reservoirs. This suggests that the reservoir fluids were not in communication with the adjacent mudstone pore fluids but were introduced from another source area, perhaps carrying a B-isotopic label derived from the hydrocarbon source region. Authigenic illite formed in the Pierre shale meta-bentonite shows large isotopic fractionations of boron (20‰) during illitization at high temperatures. Incorporation of 500 ppm B in illite formed at 500°C shows that illite is a host for B even at metamorphic temperatures. By using the experimentally

  13. Determination of Geochemical Characteristics of Glass Alteration Environments Using Boron Isotopes

    NASA Astrophysics Data System (ADS)

    Pauly, B. D.; Williams, L. B.; Hervig, R.; Zierenberg, R. A.; Schiffman, P.

    2012-12-01

    Palagonite (palagonitized sideromelane) is the initial, low-temperature alteration product of basaltic glass in the presence of water and/or water vapor. High-resolution transmission electron microscopy shows that palagonite is a mineraloid consisting of sheeted, smectite-like areas and amorphous areas. The presence of clay-like material raises the possibility for environmentally-controlled boron isotope fractionation during palagonitization, potentially similar to that observed due to formation of authigenic clay in bentonites. We measured boron isotope ratios in thin-sectioned palagonite samples using secondary-ion mass spectrometry (SIMS), and devised a procedure for in-situ removal of surface contaminants of boron as well as boron within the interlayers of this authigenic material, permitting determination of both bulk and tetrahedral boron isotopic ratios. The samples were basaltic hyaloclastites from submarine volcaniclastic, submarine volcanic, and marine phreatomagmatic environments. Measured tetrahedral boron isotopic ratios (δ11B) ranged from -7.7 (±2.2) to 43.6 (±0.9)‰. All samples with relatively heavy δ11B values also had relatively low initial porosities (determined by point counting), whereas all but one of the samples with relatively light δ11B values also had relatively high initial porosities. In previous clay mineralization studies, boron isotope fractionation has been shown to depend not only on temperature but also on the proportions of aqueous B(OH)3 and B(OH)4-, which is controlled by pH. At high pH, tetrahedral B(OH)4- is the dominant aqueous species, so relatively less B-isotope fractionation occurs than at low pH, where trigonal B(OH)3 is the dominant aqueous species. During palagonitization at high pH, the measured tetrahedral δ11B would be closer to δ11B of the water (less fractionation), whereas at low pH, the measured tetrahedral δ11B would be significantly lighter than δ11B of the water (more fractionation). Geochemical

  14. Tracing recycled volatiles in a heterogeneous mantle with boron isotopes

    NASA Astrophysics Data System (ADS)

    Walowski, Kristina; Kirstein, Linda; de Hoog, Cees-Jan; Elliot, Tim; Savov, Ivan; Devey, Colin

    2016-04-01

    Recycling of oceanic lithosphere drives the chemical evolution of the Earth's mantle supplying both solids and volatiles to the Earth's interior. Yet, how subducted material influences mantle composition remains unclear. A perfect tracer for slab recycling should be only fractionated at the Earth's surface, have a strong influence on mantle compositions but be resistant to perturbations en route back to the surface. Current understanding suggests that boron concentrations linked to B isotope determinations fulfil all these requirements and should be an excellent tracer of heterogeneity in the deep mantle. Here, we present the trace element, volatile and the B isotope composition of basaltic glasses and melt inclusions in olivine from distinct end-member ocean island basalts (OIB) to track the fate of recycled lithosphere and ultimately document how recycling contributes to mantle heterogeneity. The chosen samples represent the different end member OIB compositions and include: EMI (Pitcairn), EMII (MacDonald), HIMU (St. Helena), and FOZO (Cape Verde & Reunion). The data is derived from both submarine and subaerial deposits, with B isotope determination of both basaltic glass and melt inclusions from each locality. Preliminary results suggest OIB have B isotopic compositions that overlap the MORB array (-7.5‰±0.7; Marschall et al., 2015) but extend to both lighter and heavier values. These results suggest that B isotopes will be useful for resolving mantle source heterogeneity at different ocean islands and contribute to our understanding of the volatile budget of the deep mantle.

  15. Isotope ratio mass spectrometry in nutrition research

    SciTech Connect

    Luke, A.H.

    1994-12-31

    Many of the biochemical pathways and processes that form the foundation of modern nutrition research was elucidated using stable isotopes as physiological tracers. Since the discovery of stable isotopes, improvements and innovations in mass spectrometry and chromatography have led to greatly expanded applications. This research project was designed to evaluate gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) as a tool for isotopic tracer studies and to delineate the operational parameters for the analysis of {sup 13}C-labeled cholesterol, leucine and {alpha}-ketoisocaproate. The same isotope ratio mass spectrometer was then used as the base instrument for the ratio mass spectrometer was then used as the base instrument for the development of two additional inlet systems: a continuous-flow inlet for the analyses of {sup 13}C and {sup 18}O as CO{sub 2} and a filament inlet for on-line combustion and isotopic analysis of non-volatile organic compounds. Each of these three inlets was evaluated and their utility in nutrition research illustrated. GC/C/IRMS was used to analyze cholesterol, leucine and {alpha}-ketoisocaproate with good accuracy, precision and little isotopic memory. For all three compounds the detection limits achieved well surpassed currently used technologies. For compounds that can be well separated by GC, GC/C/IRMS is a valuable analytical tool. The continuous-flow inlet provided good accuracy and precision for measurements of {sup 13}CO{sub 2} from breath tests and {sup 18}O as CO{sub 2} from total energy expenditure tests. Most importantly, the continuous-flow inlet increased sample throughput by at least a factor of three over conventional analytical techniques. The filament inlet provided accurate and precise {sup 13}C ratio measurements of both natural abundance and enriched standards of non-volatile organic compounds of physiological interest.

  16. 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.

  17. Structure and superconductivity of isotope-enriched boron-doped diamond

    PubMed Central

    Ekimov, Evgeny A; Sidorov, Vladimir A; Zoteev, Andrey V; Lebed, Julia B; Thompson, Joe D; Stishov, Sergey M

    2008-01-01

    Superconducting boron-doped diamond samples were synthesized with isotopes of 10B, 11B, 13C and 12C. We claim the presence of a carbon isotope effect on the superconducting transition temperature, which supports the ‘diamond-carbon’-related nature of superconductivity and the importance of the electron–phonon interaction as the mechanism of superconductivity in diamond. Isotope substitution permits us to relate almost all bands in the Raman spectra of heavily boron-doped diamond to the vibrations of carbon atoms. The 500 cm−1 Raman band shifts with either carbon or boron isotope substitution and may be associated with vibrations of paired or clustered boron. The absence of a superconducting transition (down to 1.6 K) in diamonds synthesized in the Co–C–B system at 1900 K correlates with the small boron concentration deduced from lattice parameters. PMID:27878027

  18. 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.

  19. 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.

  20. Isotope Ratios of Cellulose from Plants Having Different Photosynthetic Pathways

    PubMed Central

    Sternberg, Leonel O.; Deniro, Michael J.; Johnson, Hyrum B.

    1984-01-01

    Hydrogen and carbon isotope ratios of cellulose nitrate and oxygen isotope ratios of cellulose from C3, C4, and Crassulacean acid metabolism (CAM) plants were determined for plants growing within a small area in Val Verde County, Texas. Plants having CAM had distinctly higher deuterium/hydrogen (D/H) ratios than plants having C3 and C4 metabolism. When hydrogen isotope ratios are plotted against carbon isotope ratios, each photosynthetic mode separates into a distinct cluster of points. C4 plants had many D/H ratios similar to those of C3 plants, so that hydrogen isotope ratios cannot be used to distinguish between these two photosynthetic modes. Portulaca mundula, which may have a modified photosynthetic mode between C4 and CAM, had a hydrogen isotope ratio between those of the C4 and CAM plants. When oxygen isotope ratios are plotted against carbon isotope ratios, no distinct clustering of the C4 and CAM plants occurs. Thus, oxygen isotope ratios are not useful in distinguishing between these metabolic modes. A plot of hydrogen isotope ratios versus oxygen isotope ratios for this sample set shows considerable overlap between oxygen isotope ratios of the different photosynthetic modes without a concomitant overlap in the hydrogen isotope ratios of CAM and the other two photosynthetic modes. This observation is consistent with the hypothesis that higher D/H ratios in CAM plants relative to C3 and C4 plants are due to isotopic fractionations occurring during biochemical reactions. PMID:16663460

  1. 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.

  2. 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

  3. 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

  4. Boron Isotopes in Benthic Foraminifera by MC-ICPMS: Unlocking the Ocean's Carbon Cycle

    NASA Astrophysics Data System (ADS)

    Rae, J. W.; Foster, G. L.; Schmidt, D. N.; Elliott, T. R.

    2008-12-01

    The cause of glacial-interglacial CO2 cycles has been described as the "holy grail" of climate science. All models currently proposed invoke changes in deep ocean carbon storage, but the mechanisms by which this took place remain unclear. Proxies for two components of the ocean carbonate system would allow us to fully reconstruct ocean carbonate equilibria and trace the spatial and temporal pattern of glacial carbon storage, providing valuable constraints on the causal mechanisms of atmospheric CO2 change. The theory behind the boron isotope pH proxy is well understood, but its reliability has been questioned, primarily due to uncertainty in the fractionation factor between boron species in seawater, and analytical difficulties associated with negative thermal ionisation (NTIMS) measurements. We have developed a new technique for boron isotopic analysis by multicollector inductively coupled plasma mass spectrometry (MC- ICPMS), which overcomes many of the problems associated with NTIMS measurements. Our method is precise (better than 0.25%, or ~0.02 pH units, on full procedural replicates at 95% confidence), rapid (allowing duplicate measurement of 10-20 samples per analytical session), and has small sample size requirements of ~10 ng boron (~0.5 mg foraminiferal tests). As MC-ICPMS analysis requires separation of boron prior to measurement, any bias between samples and standards with different matrices is also removed. Recent experimental work has also improved uncertainty in the isotopic fractionation factor (now measured at 1.0272 ±0.0006 [1]), providing a powerful independent means to test the behaviour of the foram-based δ11B proxy, and its ability to provide absolute pH values. We have measured δ11B in several species of benthic foraminifera from a range of core-top samples. In contrast to previous studies, we find a very close match between foraminiferal δ11B values and the δ11B of seawater B(OH)4- - predicted using the recently determined fractionation

  5. The boron and lithium isotopic composition of mid-ocean ridge basalts and the mantle

    NASA Astrophysics Data System (ADS)

    Marschall, Horst R.; Wanless, V. Dorsey; Shimizu, Nobumichi; Pogge von Strandmann, Philip A. E.; Elliott, Tim; Monteleone, Brian D.

    2017-06-01

    A global selection of 56 mid-ocean ridge basalt (MORB) glasses were analysed for Li and B abundances and isotopic compositions. Analytical accuracy and precision of analyses constitute an improvement over previously published MORB data and allow a more detailed discussion of the Li and B systematics of the crust-mantle system. Refined estimates for primitive mantle abundances ([ Li ] = 1.39 ± 0.10 μg/g and [ B ] = 0.19 ± 0.02 μg/g) and depleted mantle abundances ([ Li ] = 1.20 ± 0.10 μg/g and [ B ] = 0.077 ± 0.010 μg/g) are presented based on mass balance and on partial melting models that utilise observed element ratios in MORB. Assimilation of seawater (or brine) or seawater-altered material beneath the ridge, identified by high Cl / K , causes significant elevation of MORB δ11 B and variable elevation in δ7 Li . The B isotope ratio is, hence, identified as a reliable indicator of assimilation in MORB and values higher than -6‰ are strongly indicative of shallow contamination of the magma. The global set of samples investigated here were produced at various degrees of partial melting and include depleted and enriched MORB from slow and fast-spreading ridge segments with a range of radiogenic isotope signatures and trace element compositions. Uncontaminated (low- Cl / K) MORB show no significant boron isotope variation at the current level of analytical precision, and hence a homogenous B isotopic composition of δ11 B = - 7.1 ± 0.9 ‰ (mean of six ridge segments; 2SD). Boron isotope fractionation during mantle melting and basalt fractionation likely is small, and this δ11 B value reflects the B isotopic composition of the depleted mantle and the bulk silicate Earth, probably within ±0.4‰. Our sample set shows a mean δ7 Li = + 3.5 ± 1.0 ‰ (mean of five ridge segments; 2SD), excluding high- Cl / K samples. A significant variation of 1.0-1.5‰ exists among various ridge segments and among samples within individual ridge segments, but this

  6. Source of boron in the Palokas gold deposit, northern Finland: evidence from boron isotopes and major element composition of tourmaline

    NASA Astrophysics Data System (ADS)

    Ranta, Jukka-Pekka; Hanski, Eero; Cook, Nick; Lahaye, Yann

    2017-06-01

    The recently discovered Palokas gold deposit is part of the larger Rompas-Rajapalot gold-mineralized system located in the Paleoproterozoic Peräpohja Belt, northern Finland. Tourmaline is an important gangue mineral in the Palokas gold mineralization. It occurs as tourmalinite veins and as tourmaline crystals in sulfide-rich metasomatized gold-bearing rocks. In order to understand the origin of tourmaline in the gold-mineralized rocks, we have investigated the major element chemistry and boron isotope composition of tourmaline from three areas: (1) the Palokas gold mineralization, (2) a pegmatitic tourmaline granite, and (3) the evaporitic Petäjäskoski Formation. Based on textural evidence, tourmaline in gold mineralization is divided into two different types. Type 1 is located within the host rock and is cut by rock-forming anthophyllite crystals. Type 2 occurs in late veins and/or breccia zones consisting of approximately 80% tourmaline and 20% sulfides, commonly adjacent to quartz veins. All the studied tourmaline samples belong to the alkali-group tourmaline and can be classified as dravite and schorl. The δ11B values of the three localities lie in the same range, from 0 to -4‰. Tourmaline from the Au mineralization and from the Petäjäskoski Formation has similar compositional trends. Mg is the major substituent for Al; inferred low Fe3+/Fe2+ ratios and Na values (<0.8 atoms per formula unit (apfu)) of all tourmaline samples suggest that they precipitated from reduced, low-salinity fluids. Based on the similar chemical and boron isotope composition and the Re-Os age of molybdenite related to the tourmaline-sulfide-quartz veins, we propose that the tourmaline-forming process is a result of a single magmatic-hydrothermal event related to the extensive granite magmatism at around 1.79-1.77 Ga. Tourmaline was crystallized throughout the hydrothermal process, which resulted in the paragenetic variation between type 1 and type 2. The close association of

  7. Source of boron in the Palokas gold deposit, northern Finland: evidence from boron isotopes and major element composition of tourmaline

    NASA Astrophysics Data System (ADS)

    Ranta, Jukka-Pekka; Hanski, Eero; Cook, Nick; Lahaye, Yann

    2016-11-01

    The recently discovered Palokas gold deposit is part of the larger Rompas-Rajapalot gold-mineralized system located in the Paleoproterozoic Peräpohja Belt, northern Finland. Tourmaline is an important gangue mineral in the Palokas gold mineralization. It occurs as tourmalinite veins and as tourmaline crystals in sulfide-rich metasomatized gold-bearing rocks. In order to understand the origin of tourmaline in the gold-mineralized rocks, we have investigated the major element chemistry and boron isotope composition of tourmaline from three areas: (1) the Palokas gold mineralization, (2) a pegmatitic tourmaline granite, and (3) the evaporitic Petäjäskoski Formation. Based on textural evidence, tourmaline in gold mineralization is divided into two different types. Type 1 is located within the host rock and is cut by rock-forming anthophyllite crystals. Type 2 occurs in late veins and/or breccia zones consisting of approximately 80% tourmaline and 20% sulfides, commonly adjacent to quartz veins. All the studied tourmaline samples belong to the alkali-group tourmaline and can be classified as dravite and schorl. The δ11B values of the three localities lie in the same range, from 0 to -4‰. Tourmaline from the Au mineralization and from the Petäjäskoski Formation has similar compositional trends. Mg is the major substituent for Al; inferred low Fe3+/Fe2+ ratios and Na values (<0.8 atoms per formula unit (apfu)) of all tourmaline samples suggest that they precipitated from reduced, low-salinity fluids. Based on the similar chemical and boron isotope composition and the Re-Os age of molybdenite related to the tourmaline-sulfide-quartz veins, we propose that the tourmaline-forming process is a result of a single magmatic-hydrothermal event related to the extensive granite magmatism at around 1.79-1.77 Ga. Tourmaline was crystallized throughout the hydrothermal process, which resulted in the paragenetic variation between type 1 and type 2. The close association of

  8. Boron-cycling by subducted lithosphere; insights from boron-isotope compositions of the Kokchetav tourmalines

    NASA Astrophysics Data System (ADS)

    Ota, T.; Kobayashi, K.; Moriguti, T.; Nakamura, E.

    2007-12-01

    For understanding the Earth's chemical evolution, the role of subducting plates has long been focused on. Stable isotopes can provide critical evidence to identify materials experienced geological processes near the surface. In this study, we examined B-isotope compositions of tourmalines from the Kokchetav diamondiferous UHP metamorphic belt, particularly a recently discovered high-K tourmaline from Kumdy-kol[1]. The high-K tourmaline occurs in Qtz-Kfs layers, alternating with Grt-Cpx-Bt-Qtz rocks. It has microdiamond- bearing and K-rich (K2O=~2.38 wt.%) cores, which yield heavy B-isotope ratios (δ11B=+3.2~+7.7, analyzed by SIMS). Our results suggest that the high-K tourmaline would be crystallized under high-pressure within the diamond stability from fluids or melts with the surficial B-isotope signature, which is clearly different from that of ordinary tourmalines (δ11B=-16.6~-2.3) experienced the isotope fractionation through subduction-related dehydration reactions. Tourmalines with heavy B-isotope ratios have been described from marine evaporites and carbonates[2]. The presence of silicate-carbonate melt inclusions with microdiamonds in metacarbonate rocks from Kumdy- kol[3] implies that the heavy B-isotope in the high-K tourmaline might have derived from the melt preserved in the metacarbonate rocks. However, recrystallized carbonates can yield light B-isotope ratios (δ11B=~-5[4]), and it is doubtful that carbonates could have retained the heavy B-isotope signature during subduction to the depths. The alternative source of the heavy B-isotope is serpentinite in hydrated lithospheric mantle, because serpentinized peridotites are enriched in heavy B-isotope (δ11B=+5.4~+25[5]). Serpentinization of subducting lithospheric mantle, with enrichment of heavy B-isotope, can be realized by transform faulting near oceanic ridges and normal faulting at trench-outer rise regions, followed by penetration of seawater into the lithospheric mantle prior to subduction[6

  9. Lithium and Boron Isotope Systematics of Igneous and Metamorphic Rocks

    NASA Astrophysics Data System (ADS)

    Nakamura, E.; Moriguti, T.; Kobayashi, K.; Tanaka, R.; Watanabe, M.

    2006-05-01

    Stable isotope systems, which strongly fractionate under low-temperature near surface conditions (<~600°C) and in the subduction environment, have a potential to identify the existence of 'recycled material' in the mantle source of oceanic basalt. In particular, lithium (Li) and boron (B) isotopes could be powerful geochemical tracers of tracing this geochemical pathway. Li and B are fluid-mobile elements; therefore, the mass fractionation is enhanced by fluid-rock interactions on the ocean floor and during metamorphic dehydration through the material recycling. Studies, focused on Li and B systematics in high- pressure metamorphic systems, suggested that the isotopic composition of both these isotopes in the oceanic crust subducted into the deep mantle are lighter than surrounding mantle materials, thus producing mantle heterogeneity. Li and B isotopes with "near-surface" signature, therefore, might be detectable in ocean island basalt samples, which are considered to include recycled materials. Given the constraints on the physicochemical behavior of Li and B in the subduction cycle, isotope systematics of these elements in the ocean island basalts may be the key in understanding crust-mantle recycling. In this talk, we will focus on the recent studies carried out on Li and B isotopic variation in Hawaiian volcanoes and also introduce the topic on the behavior of Li and B through subduction zone metamorphism. A recent study employing HR-SIMS revealed significant Li and B isotopic variation of olivine glass (melt) inclusions from Hawaiian lavas (Kobayashi et al., 2004). While our studies on olivine inclusions show large variations ranging between -10.2 and +8.4 ‰ for δ7Li and from -10.5 to +5.2 ‰ for δ11B, the whole rock samples are limited to be ranging from +2.2 to +5.7 ‰ for δ7Li (Chen and Frey, 2003) and between 5.4 and -3.0 ‰ for δ11B (Tanaka and Nakamura, 2005). These results suggest that the glass inclusions preserve better information

  10. 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.

  11. The Boron Isotopic Composition of Elephant Dung: Inputs to the Global Boron Budget

    NASA Astrophysics Data System (ADS)

    Williams, L. B.; Hervig, R. L.

    2011-12-01

    A survey of boron in kerogen showed isotopically light δ11B values (0 to -50%) that are distinctly different from most mineral and natural water B reservoirs. Diagenesis releases this isotopically light B into pore fluids when hydrocarbons are generated, thus enriching oilfield brines in 10B. This observation suggests that borated biomolecules (BM) are primarily tetrahedral favoring 10B, whereas 11B is preferred in trigonal coordination. Plants, with optimal concentrations up to 100ppm, contribute more B than animal remains to sediment. Elephants are one of the largest herbivores on earth, consuming 200 - 250 kg of plant material/day and producing 50 kg of manure/day. They are inefficient at digestion, thus the manure contains >50% undigested plant material. Dung samples are therefore ideal for studying the δ11B of both the food input and digested output of a significant B supply to sedimentary systems. Horse and rabbit manure were studied for comparison to evaluate B isotope variations in the food supply and potential vital effects on the output. B-content and isotopic composition of dung plant material and digested fractions were measured in the solid state by secondary ion mass spectrometry. The digests were rinsed in 1.8% mannitol, a B-complexing agent, to remove surface adsorbed-B, then air dried and Au-coated for charge compensation. Results showed that the elephant diet contains 3-13 ppm B, with an average δ11B of -20 ± 0.8% (1σ), while rabbit food had 88 ppm B with a δ11B of -50 ± 1.3 %. The digested fraction of the elephant dung contains 4-10ppm B with average δ11B values of -12 ± 1.2%. In comparison, horse manure with 11-21 ppm B has a δ11B of -10.7 ± 0.5% and rabbit manure contains 2-3 ppm B with a δ11B of -8.8 ± 1%. Boron isotope compositions of these manures are indistinguishable (within error). Clearly plant material is a major contributor of isotopically light B to sediments. The herbivores studied fractionate their total B intake in

  12. Authentication of bell peppers using boron and strontium isotope compositions

    NASA Astrophysics Data System (ADS)

    Rosner, Martin; Pritzkow, Wolfgang; Vogl, Jochen; Voerkelius, Susanne

    2010-05-01

    The wrong declaration of food in terms of geographical origin and production method is a major problem for the individual consumer and public regulatory authorities. The authentication of food matrices using H-C-N-O-S isotopic compositions is already well established. However, specific questions require additional isotopic systems, which are more diagonstic for the source reservoires involved or production methods used. Here we present B and Sr isotopic compositions of bell peppers from Europe (Germany, Austria, Netherlands, Spain) and Israel to verfiy their origin. The bell peppers' B isotopic compositions between different locations are highly variable (d11BNISTSRM951 -8 to +35 ‰), whereas the 87Sr/86Sr ratios are all close to modern seawater Sr isotopic composition of about 0.7092 (0.7078 to 0.7107), but still can reliably be distinguished. Distinct isotopically heavy and light B isotopic fingerprints are obtained for bell peppers from Israel and the Netherlands. Samples from Germany, Austria, and Spain display overlapping d11B values between 0 and +12 ‰. Bell peppers from Israel show high d11B values (+28 to +35 ‰) combined with 87Sr/86Sr ratios slightly more unradiogenic than modern seawater (ca 0.7079). Bell peppers from the Netherlands, however, show low d11B values (-8 ‰) combinded with 87Sr/86Sr ratios of modern seawater (approx. 0.7085). Mainly based on diagnostic B isotopic compositions bell peppers from Israel and the Netherlands can be related to a specific geographical growing environment (Israel) or production method (Netherlands). The isotope fingerprints of bell peppers from the Netherlands are consistent with growing conditions in greenhouses typical for the Netherlands vegetable farming. Using optimized production methods crops in greenhouses were supplied with nutritients by liquid fertilizers on artificial substrates. As most fertilizers derive from non-marine salt deposits, fertilization typically imprints invariant d11B values close

  13. Determination of boron content and isotopic composition in gypsum by inductively coupled plasma optical emission spectroscopy and positive thermal ionization mass spectrometry using phase transformation.

    PubMed

    Ma, Yun-Qi; Peng, Zhang-Kuang; Yang, Jian; Xiao, Ying-Kai; Zhang, Yan-Ling

    2017-12-01

    As a stable isotope, boron plays an important role in hydrogeology, environmental geochemistry, ore deposit geochemistry and marine paleoclimatology. However, there is no report of boron isotopic composition in gypsum. This is mainly confined to complete dissolution of Gypsum by water or acid. In this study, gypsum was converted to calcium carbonate (CaCO3) with ammonium bicarbonate(NH4HCO3) by two steps at 50°C. In every step, the mass ratio of NH4HCO3/CaSO4·2H2O was twice, and conversion rate reached more than 98%. Converted CaCO3 was totally dissolved with hydrochloric acid (the dissolution rate was over 99%). In order to overcome the difficulties of the matrix interference and the detection limit of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), we use Amberlite IRA 743 resin to purify and enrichment the boron at first, then eluting boron from the resin with 10mL 0.1mol/L hydrochloric acid at 75°C. The boron isotopic composition of natural gypsum samples was determined using positive thermal ionization mass spectrometry (P-TIMS). The boron isotopic composition of gypsum may be an excellent indicator for the formation environment. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. 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.

  15. Isotopic ratio method for determining uranium contamination

    SciTech Connect

    Miles, R.E.; Sieben, A.K.

    1994-02-03

    The presence of high concentrations of uranium in the subsurface can be attributed either to contamination from uranium processing activities or to naturally occurring uranium. A mathematical method has been employed to evaluate the isotope ratios from subsurface soils at the Rocky Flats Nuclear Weapons Plant (RFP) and demonstrates conclusively that the soil contains uranium from a natural source and has not been contaminated with enriched uranium resulting from RFP releases. This paper describes the method used in this determination which has widespread application in site characterizations and can be adapted to other radioisotopes used in manufacturing industries. The determination of radioisotope source can lead to a reduction of the remediation effort.

  16. Boron isotopes in Fiji corals and precise ocean acidification reconstruction

    NASA Astrophysics Data System (ADS)

    Douville, E.; Juillet-Leclerc, A.; Cabioch, G.; Louvat, P.; Gaillardet, J.; Gehlen, M.; Bopp, L.; Paterne, M.

    2009-12-01

    Within the framework of EPOCA (European Project on OCean Acidification ) and the French INSU project PHARE, we are adapting the boron isotope technique to ancient corals with the scope to reconstruct “past” ocean pH changes. In this study, we applied the technique to surface seawater pH reconstructions based on tropical 20th century corals from Fiji. Models estimated a pH drop close to 0.07 pH units in the South Western Equatorial Pacific since the onset of the industrial era (Sabine et al., 2004). To reconstruct such a change in pH, the isotopic composition of boron (δ11B) in coral material has to be determined with a precision better than ±0.2‰. This analytical criteria was meet on a Multi-Collector ICPMS Neptune. We selected a Porites coral for the reconstruction of the time dependent evolution of pH. Our results show a progressive decrease of seawater pH between 1900 and 2000 of 0.08 +/- 0.02 pH units. This decrease in pH agrees with projections of surface ocean pH for the Fiji area obtained with the biogeochemical ocean circulation model NEMO-PISCES. Our results further reveal that seawater pH changes in the Fiji area are strongly affected by regional processes such as the South Pacific Convergence Zone (SPCZ) tightly linked the Pacific Decadal Oscillation (PDO). This last observation highlights the potential of the δ11B-pH technique for studying past changes of ocean dynamics. Hönisch, B., Hemming, N. G., Grottoli, A. G., Amat, A., Hanson, G. N. & Bijma, J. (2004). Assessing scleractinian corals as recoders for paleo-pH: Empirical calibration and vital effects. Geochimica et Cosmochimica Acta, 68(18), 3675-3685. Sabine, C. L., Feely, R. A., Gruber, N., Key, R. M., Lee, K., Bullister, J. L., Wanninkhof, R., Wong, C. S., Wallace, D. W. R., Tilbrook, B., Millero, F. J., Peng, T. H., Kozyr, A., Ono, T. & Rios, A. F. (2004). The Oceanic Sink for Anthropogenic CO2. Science, 305, 367-371.

  17. Glacial-interglacial Changes in Ocean Carbon Chemistry constrained by Boron Isotopes, Trace Elements, and Modelling

    NASA Astrophysics Data System (ADS)

    Rae, J. W. B.; Adkins, J. F.; Foreman, A. D.; Charles, C.

    2014-12-01

    Deep ocean carbon storage and release is commonly invoked to explain glacial-interglacial CO2 cycles, but records of the carbonate chemistry of the glacial ocean have, until recently, been scarce. Here we present new boron isotope (δ11B) and trace metal data from benthic foraminifera from a suite of 15 cores from the South Atlantic from depths ranging from 1500 to 4000 m. These records show distinct changes in the water column depth structure of these tracers between the last glacial maximum (LGM) and late Holocene. Comparison of these paired trace element and isotope ratios reveals new insights to the shared and individual controls on tracers including Li/Ca, Sr/Ca, U/Ca, Mg/Li and δ11B. We further examine these data using a recently developed tracer fields modelling approach (Lund et al. 2011). This has previously been applied to δ18O data to investigate changes in circulation at the LGM. Here we extend this method to non-conservative isotopic and trace elemental tracers, allowing us to constrain the roles of circulation, the biological pump of organic carbon and CaCO3, and carbonate compensation, in setting deep ocean carbon storage at the LGM. Lund, D. C., J. F. Adkins, and R. Ferrari (2011), Abyssal Atlantic circulation during the Last Glacial Maximum: Constraining the ratio between transport and vertical mixing, Paleoceanography, 26, PA1213, doi:10.1029/2010PA001938.

  18. Isotope ratio analysis by Orbitrap mass spectrometry

    NASA Astrophysics Data System (ADS)

    Eiler, J. M.; Chimiak, L. M.; Dallas, B.; Griep-Raming, J.; Juchelka, D.; Makarov, A.; Schwieters, J. B.

    2016-12-01

    Several technologies are being developed to examine the intramolecular isotopic structures of molecules (i.e., site-specific and multiple substitution), but various limitations in sample size and type or (for IRMS) resolution have so far prevented the creation of a truly general technique. We will discuss the initial findings of a technique based on Fourier transform mass spectrometry, using the Thermo Scientific Q Exactive GC — an instrument that contains an Orbitrap mass analyzer. Fourier transform mass spectrometry is marked by exceptionally high mass resolutions (the Orbitrap reaches M/∆M in the range 250,000-1M in the mass range of greatest interest, 50-200 amu). This allows for resolution of a large range of nearly isobaric interferences for isotopologues of volatile and semi-volatile compounds (i.e., involving isotopes of H, C, N, O and S). It also provides potential to solve very challenging mass resolution problems for isotopic analysis of other, heavier elements. Both internal and external experimental reproducibilities of isotope ratio analyses using the Orbitrap typically conform to shot-noise limits down to levels of 0.2 ‰ (1SE), and routinely in the range 0.5-1.0 ‰, with similar accuracy when standardized to concurrently run reference materials. Such measurements can be made without modifications to the ion optics of the Q Exactive GC, but do require specially designed sample introduction devices to permit sample/standard comparison and long integration times. The sensitivity of the Q Exactive GC permits analysis of sub-nanomolar samples and quantification of multiply-substituted species. The site-specific capability of this instrument arises from the fact that mass spectra of molecular analytes commonly contain diverse fragment ion species, each of which samples a specific sub-set of molecular sites. We will present applications of this technique to the biological and abiological chemistry of amino acids, forensic identification of

  19. 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.

  20. The boron isotope systematics of the Yellowstone National Park (Wyoming) hydrothermal system: A reconnaissance

    SciTech Connect

    Palmer, M.R. ); Sturchio, N.C. )

    1990-10-01

    Boron concentrations and isotope compositions have been measured in fourteen hot spring waters, two drill hole waters, an unaltered rhyolite flow, and hydrothermally altered rhyolite from the geothermal system in Yellowstone National Park, Wyoming. The samples are representative of the major thermal areas within the park and span the range of fluid types. For the fluids, the B concentrations range from 0.043-2.69 mM/kg, and the {delta}{sup 11}B values range from {minus}9.3 to +4.4{per thousand}. There is no relationship between the dissolved B concentrations or isotope compositions with the concentration of any major element (other than Cl) or physical property. Each basin is characterized by a restricted range in B/Cl ratios and {delta}{sup 11}B values. Hot spring waters from the Norris Basin, Upper Geyser Basin, Calcite Springs, and Clearwater have {delta}{sup 11}B values close to that of unaltered rhyolite ({minus}5.2{per thousand}) and are interpreted to have derived their B from this source. Waters from Mammoth Hot Springs, Sheepeater, and Rainbow Springs have lower {delta}{sup 11}B values close to {minus}8{per thousand}. These lower values may reflect leaching of B from sedimentary rocks outside the Yellowstone caldera, but they are similar to the {delta}{sup 11}B value of hydrothermally altered rhyolite ({minus}9.7{per thousand}). Hence, the light boron isotope compositions recorded in these hot spring waters may reflect leaching of previously deposited hydrothermal minerals. Cooler springs along the Yellowstone River just outside the park boundary have lower B concentrations and higher {delta}{sup 11}B values that may reflect mixing with shallow meteoric water.

  1. The boron isotope systematics of the Yellowstone National Park (Wyoming) hydrothermal system: A reconnaissance

    NASA Astrophysics Data System (ADS)

    Palmer, M. R.; Sturchio, N. C.

    1990-10-01

    Boron concentrations and isotope compositions have been measured in fourteen hot spring waters, two drill hole waters, an unaltered rhyolite flow, and hydrothermally altered rhyolite from the geothermal system in Yellowstone National Park, Wyoming. The samples are representative of the major thermal areas within the park and span the range of fluid types. For the fluids, the B concentrations range from 0.043-2.69 mM/kg, and the δ11B values range from -9.3 to +4.4%.. There is no relationship between the dissolved B concentrations or isotope compositions with the concentration of any major element (other than Cl) or physical property. Each basin is characterized by a restricted range in B/Cl ratios and δ11B values. Hot spring waters from the Morris Basin, Upper Geyser Basin, Calcite Springs, and Clearwater have δ11B values close to that of unaltered rhyolite (-5.2%.) and are interpreted to have derived their B from this source. Waters from Mammoth Hot Springs, Sheepeater, and Rainbow Springs have lower δ11B values close to -8%.. These lower values may reflect leaching of B from sedimentary rocks outside the Yellowstone caldera, but they are similar to the δ11B value of hydrothermally altered rhyolite (-9.7%.). Hence, the light boron isotope compositions recorded in these hot spring waters may reflect leaching of previously deposited hydrothermal minerals. Cooler springs along the Yellowstone River just outside the park boundary have lower B concentrations and higher δ11B values that may reflect mixing with shallow meteoric water.

  2. Use of Sulphur and Boron Isotopes to Identify Natural Gas Processing Emissions Sources

    NASA Astrophysics Data System (ADS)

    Bradley, C. E.; Norman, A.; Wieser, M. E.

    2003-12-01

    Natural gas processing results in the emission of large amounts of gaseous pollutants as a result of planned and / or emergency flaring, sulphur incineration, and in the course of normal operation. Since many gas plants often contribute to the same air shed, it is not possible to conclusively determine the sources, amounts, and characteristics of pollution from a particular processing facility using traditional methods. However, sulphur isotopes have proven useful in the apportionment of sources of atmospheric sulphate (Norman et al., 1999), and boron isotopes have been shown to be of use in tracing coal contamination through groundwater (Davidson and Bassett, 1993). In this study, both sulphur and boron isotopes have been measured at source, receptor, and control sites, and, if emissions prove to be sufficiently distinct isotopically, they will be used to identify and apportion emissions downwind. Sulphur is present in natural gas as hydrogen sulphide (H2S), which is combusted to sulphur dioxide (SO2) prior to its release to the atmosphere, while boron is present both in hydrocarbon deposits as well as in any water used in the process. Little is known about the isotopic abundance variations of boron in hydrocarbon reservoirs, but Krouse (1991) has shown that the sulphur isotope composition of H2S in reservoirs varies according to both the concentration and the method of formation of H2S. As a result, gas plants processing gas from different reservoirs are expected to produce emissions with unique isotopic compositions. Samples were collected using a high-volume air sampler placed directly downwind of several gas plants, as well as at a receptor site and a control site. Aerosol sulphate and boron were collected on quartz fibre filters, while SO2 was collected on potassium hydroxide-impregnated cellulose filters. Solid sulphur samples were taken from those plants that process sulphur in order to compare the isotopic composition with atmospheric measurements. A

  3. Boron isotope geochemistry of the oceanic crust from DSDP/ODP Hole 504B

    SciTech Connect

    Ishikawa, Tsuyoshi; Nakamura, Eizo )

    1992-04-01

    Boron contents and boron isotopic compositions were determined for the uppermost 1.3 km section of typical 6.2 Ma oceanic crust from DSDP/ODP Hole 504B, Costa Rica Rift, Galapagos Spreading Center. Both the boron content and the {delta}{sup 11}B value in the oceanic crust are controlled by two types of alteration: (1) low-temperature alteration (0 to 60C; Zones 1 and 2) and (2) high-temperature hydrothermal alteration (200 to 400C; Zones 3 and 4). Basalts subjected to the low-temperature alteration are characterized by their relatively high boron contents (0.69 to 19.3 ppm) and high {delta}{sup 11}B values (+2.2 to +10.6{per thousand}), indicating uptake of boron into secondary phases in equilibrium with seawater or evolved seawater. Hydrothermally altered basalts contain less abundant boron (0.17 to 0.52 ppm) and relatively constant {delta}{sup 11}B values ({minus}0.1 to +1.0{per thousand}). Although basalts from the upper part of these hydrothermal zones (< 1,300 mbsf) show equilibrated boron content and {delta}{sup 11}B value with aqueous fluid, effective leaching of boron from basalt is predominant in the lower part (> 1,300 mbsf). Original boron content and {delta}{sup 11}B value of the Hole 504B MORB were 0.35 ppm and +0.2{per thousand}, respectively. The present data provide fundamental information in understanding of the distribution of boron and boron isotopes in the oceanic crust.

  4. 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.

  5. A new boron isotope-pH calibration for Orbulina universa, with implications for understanding and accounting for 'vital effects'

    NASA Astrophysics Data System (ADS)

    Henehan, Michael J.; Foster, Gavin L.; Bostock, Helen C.; Greenop, Rosanna; Marshall, Brittney J.; Wilson, Paul A.

    2016-11-01

    Boron isotope ratios, as measured in planktic foraminifera, can be a useful tracer of past ocean pH, and hence help to discern the concentration of CO2 in the ancient atmosphere. However, different species of planktic foraminifera demonstrate different patterns of boron isotope variation with ambient seawater pH. Therefore when applying the proxy to questions in the geological past, species-specific calibrations are preferable. Beyond the evolutionary history of a calibrated species, we must rely on our understanding of the causes of the observed "vital effects" in the modern ocean, and the applicability of that understanding to extinct species. Here we present a new open-ocean calibration of the planktic foraminifera Orbulina universa, measured via Multi-Collector Inductively Coupled Mass Spectrometry (MC-ICPMS). Unlike other symbiont-bearing foraminifera, O. universa record a δ11 B (and hence pH) that is lower than its surrounding seawater, but with a pH-sensitivity roughly equal to that of aqueous borate ion. We discuss the significance of this for application of the boron isotope proxy in deep time, with recommendations for best practice and future research directions.

  6. Development of laser ablation multi-collector inductively coupled plasma mass spectrometry for boron isotopic measurement in marine biocarbonates: new improvements and application to a modern Porites coral.

    PubMed

    Thil, François; Blamart, Dominique; Assailly, Caroline; Lazareth, Claire E; Leblanc, Thierry; Butsher, John; Douville, Eric

    2016-02-15

    Laser Ablation coupled to Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICPMS) is a powerful tool for the high-precision measurement of the isotopic ratios of many elements in geological samples, with the isotope ratio ((11) B/(10) B) of boron being used as an indicator of the pH of oceanic waters. Most geological samples or standards are polished and ablation occurs on flat surfaces. However, the shape and the irregularities of marine biocarbonates (e.g., corals, foraminifera) can make precise isotopic measurements of boron difficult. Even after polishing, the porosity properties and the presence of holes or micro-fractures affect the signal and the isotopic ratio when ablating the material, especially in raster mode. The effect of porosity and of the crater itself on the (11) B signal and the isotopic ratio acquired by LA-MC-ICPMS in both raster and spot mode was studied. Characterization of the craters was then performed with an optical profilometer to determine their shapes and depths. Surface state effects were examined by analyzing the isotopic fractionation of boron in silicate (NIST-SRM 612 and 610 standards) and in carbonate (corals). Surface irregularities led to a considerable loss of signal when the crater depth exceeded 20 µm. The stability and precision were degraded when ablation occurred in a deep cavity. The effect of laser focusing and of blank correction was also highlighted and our observations indicate that the accuracy of the boron isotopic ratio does not depend on the shape of the surface. After validation of the analytical protocol for boron isotopes, a raster application on a Porites coral, which grew for 18 months in an aquarium after field sampling, was carried out. This original LA-MC-ICPMS study revealed a well-marked boron isotope ratio temporal variability, probably related to growth rate and density changes, irrespective of the pH of the surrounding seawater. Copyright © 2015 John Wiley & Sons, Ltd. Copyright

  7. Boron isotope evidence for the involvement of non-marine evaporites in the origin of the Broken Hill ore deposits

    USGS Publications Warehouse

    Slack, J.F.; Palmer, M.R.; Stevens, B.P.J.

    1989-01-01

    IDENTIFYING the palaeogeographic setting and mode of origin of stratabound ore deposits can be difficult in high-grade metamorphic terranes, where the effects of metamorphism may obscure the nature of the protoliths. Here we report boron isotope data for tourmalines from the early Proterozoic Broken Hill block, in Australia, which hosts giant lead-zinc-silver sulphide deposits. With one exception the 11B/10B ratios are lower than those for all other tourmalines from massive sulphide deposits and tour-malinites elsewhere in the world. We propose that these low ratios reflect leaching of boron from non-marine evaporitic borates by convecting hydrothermal fluids associated with early Proterozoic continental rifting. A possible modern analogue is the Salton Sea geothermal field in California. ?? 1989 Nature Publishing Group.

  8. Uniform Silicon Isotope Ratios Across the Milky Way Galaxy

    NASA Astrophysics Data System (ADS)

    Monson, Nathaniel N.; Morris, Mark R.; Young, Edward D.

    2017-04-01

    We report the relative abundances of the three stable isotopes of silicon, 28Si, 29Si, and 30Si, across the Galaxy using the v=0,J=1\\to 0 transition of silicon monoxide. The chosen sources represent a range in Galactocentric radii ({R}{GC}) from 0 to 9.8 kpc. The high spectral resolution and sensitivity afforded by the Green Bank Telescope permit isotope ratios to be corrected for optical depths. The optical-depth-corrected data indicate that the secondary-to-primary silicon isotope ratios {}29{Si}{/}28{Si} and {}30{Si}{/}28{Si} vary much less than predicted on the basis of other stable isotope ratio gradients across the Galaxy. Indeed, there is no detectable variation in Si isotope ratios with {R}{GC}. This lack of an isotope ratio gradient stands in stark contrast to the monotonically decreasing trend with {R}{GC} exhibited by published secondary-to-primary oxygen isotope ratios. These results, when considered in the context of the expectations for chemical evolution, suggest that the reported oxygen isotope ratio trends, and perhaps those for carbon as well, require further investigation. The methods developed in this study for SiO isotopologue ratio measurements are equally applicable to Galactic oxygen, carbon, and nitrogen isotope ratio measurements, and should prove useful for future observations of these isotope systems.

  9. ICP-MS for isotope ratio measurement

    USDA-ARS?s Scientific Manuscript database

    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 ...

  10. Boron's Isotopes Help Trace Water in New Zealand

    NASA Astrophysics Data System (ADS)

    Slade, A.; Whitehead, B.

    2010-12-01

    Using boron isotopic composition (δ11B) values from different bodies of water (surface and ground) in New Zealand to trace the water as it moves through a portion of the hydrologic system. This research focuses on two major rivers, the Tarawera and the Rangitaiki, as they cross the Rangitaiki plains in the Bay of Plenty region of the North Island. The Tarawera River is 59 km (37 miles) long, from the mouth of Lake Tarawera, west of the Rangitaiki plains, to the ocean outlet. The lower reaches (42 km or 26 miles) of the 155 km (94 miles) Rangitaiki River travels a similar course across the plains south of, and running parallel to, the Tarawera River. Geothermal activity, plantation forests, municipal activities, wood processing industries, a pulp and paper mill, and agricultural practices all contribute to the chemical makeup of the Tarawera River. The two main industries that influence the lower reaches of the Rangitaiki River, after the dam at Lake Matahina, are a dairy milk processing plant and farming, both dairy and horticultural. Currently, more data has been collected on the Tarawera River because of the greater number of influences on it. The results of this research have revealed distinctly different δ11B signatures for the two rivers. In addition, along the Tarawera River there are significant differences in the δ11B values between the sampling sites that appear to correlate well with different inputs into the river. The added benefit of the spatial representation of the δ11B data, obtained from all the sampling sites on the Rangitaiki plains, aids in visualizing how this information can help trace the water in the hydrologic system of this area.

  11. Boron Isotopic Fractionation During the First ~50 km of Sediment Subduction in the Nankai Trough, Japan

    NASA Astrophysics Data System (ADS)

    Feineman, M. D.; Hudak, M. R.; Saffer, D. M.; Agostini, S.

    2015-12-01

    Subduction zones are the primary locus for recycling of crustal material into the Earth's mantle, with important implications for mantle and crustal evolution. Subducted sediments contribute volatiles, trace elements, and unique isotopic signatures to arc magmas and some mantle domains. While some elements appear to be conservative during sediment subduction, others may be mobilized and isotopically fractionated during the first several tens of kilometers of subduction - well before reaching sub-arc depths. Characterization of the geochemical processes occurring in this early stage of subduction is relatively limited and largely based on the compositions of fluids expelled from the accretionary prism. In order to better understand the life cycle of boron as it is processed through the subduction system, B concentrations and isotope ratios were measured in a suite of shales from the Shimanto Belt, Shikoku Island, Japan. These shales represent pelagic and neritic sediments from the Nankai Trough that have been partially subducted, underplated, and exhumed. As a counterpoint to the mobile and potentially fractionated boron, Pb isotopes (which are not expected to be fractionated by shallow subduction processes) were used to ensure that the sediments studied were derived from a homogeneous source. Peak temperatures of 140-280˚C are constrained by offshore vitrinite reflectance studies. We find that δ11B in the subducted sediment ranges from -6.6 to -9.9‰, with a negative correlation between δ11B and temperature. In contrast, B concentrations show no systematic relationship with temperature. Measured δ11B of -9.7 in the Sanbagawa schist, possibly a high-pressure-temperature analog of the Shimanto shale, is consistent with previous studies. However, 208Pb/204Pb and 207Pb/204Pb ratios indicate that the pelitic schist analyzed in this study was not derived from the same source rock as the Shimanto shale. Further work is needed to determine if there exists an

  12. Boron isotopes and B/Ca in benthic foraminifera: Proxies for the deep ocean carbonate system

    NASA Astrophysics Data System (ADS)

    Rae, James W. B.; Foster, Gavin L.; Schmidt, Daniela N.; Elliott, Tim

    2011-02-01

    Accurate records of the state of the ocean carbonate system are critical for understanding past changes in pCO 2, ocean acidification and climate. The chemical principles underlying the proxy of oceanic pH provided by the boron isotope ratio of foraminiferal carbonate are relatively well understood, but the proxy's reliability has been questioned. We present 76 new Multi-Collector Inductively-Coupled Plasma Mass Spectrometry (MC-ICPMS) δ11B measurements on a range of benthic foraminifera from 23 late-Holocene samples from the Atlantic that reaffirm the utility of the δ11B-pH proxy. Our boron isotope measurements on ~ 10 benthic foraminifera tests typically yield a precision of ~ ± 0.25‰ at 2 s.d. (equivalent to ~ ± 0.03 pH units). δ11B values of epifaunal species are within analytical uncertainty of those predicted from a simple model assuming sole incorporation of B(OH) 4- from seawater and no vital effects, using the independently determined fractionation factor of 1.0272 between 11B/ 10B of aqueous boron species. Infaunal foraminifera are consistent with this model, but record the combined effects of lower pore-water δ11B and pH. No influence of partial dissolution or shell size on δ11B is observed. We have also measured the B/Ca ratios of the same samples. For individual Cibicidoides species, B/Ca shows a good correlation with Δ[CO 32-], but the B/Ca of different co-occurring species morphotypes varies considerably. These effects are not seen in δ11B, which may therefore provide a more robust proxy of the ocean carbonate system. Whilst in theory δ11B and B/Ca can be combined to provide a quantitative reconstruction of alkalinity and dissolved inorganic carbonate (DIC), in practice this is precluded by propagated uncertainties. δ11B data give significant constraints on foraminifera calcification mechanisms, and seem most simply explained by incorporation of B(OH) 4- into a HCO 3- pool, which is then completely incorporated in foraminiferal CaCO 3

  13. Boron isotope composition of secondary smectite in suevites at the Ries crater, Germany: Boron fractionation in weathering and hydrothermal processes

    NASA Astrophysics Data System (ADS)

    Muttik, Nele; Kirsimäe, Kalle; Newsom, Horton E.; Williams, Lynda B.

    2011-10-01

    The 24-km diameter Ries crater, in Germany, is one of the best-preserved terrestrial complex impact structure and clay minerals in the groundmass of the Ries suevites have been recognized for several decades. It is generally accepted that these clays were formed by post-impact aqueous alteration of impact-generated glasses and/or finely comminuted crystalline basement material at temperatures above ambient conditions. The Ries impact structure provides a good opportunity to study the evolution of post-impact development of impact craters. Here we present a study of boron isotopic compositions (δ 11B) and B concentrations of the secondary smectite clay fraction in fall-out and crater suevites from the Ries crater (Germany). These data were used to study the boron fractionation in clay mineral precipitation processes and to model, using B-isotope fractionation, the characteristics (pH, temperature, and salinity) of fluids during fluid-rock interaction at different positions within the crater. The results of this study show that the boron isotopic composition of smectite in fall-out suevites sampled from 4 different locations (average - 24.5 ± 1.8‰) was significantly different from that of the smectite in crater suevites sampled from the Nördlingen 1973 drill core at different depth intervals, from 370 m to 525 m (average - 4.07‰). Similarly, the δ 11B composition of the fluids responsible for the alteration calculated from smectite isotopic composition in the fall-out suevites (+ 7.5 ± 1.6‰), differed from the alteration fluid composition in crater suevites (+ 17.6 ± 10.8‰); indicating a different origin of the fluids responsible for the alteration of the fall-out and crater suevites in the Ries crater. Our results suggest that the alteration in fall-out suevites occurred at lower temperatures than the crater suevites and at a lower pH, which is consistent with the smectite precipitation in equilibrium with meteoritic fluids. The boron isotopic

  14. Boron Isotopes Analyses of Carbonates, Phosphates and Silicates by Laser Ablation MC-ICP-MS: the Influence of Sample Matrix

    NASA Astrophysics Data System (ADS)

    Gerdes, A.

    2013-12-01

    Methods for in-situ analyses of boron isotopes by laser ablation MC-ICP-MS, although presented by 3 labs over the last years, are still not routinely applied despite of the growing interest in B isotopes, e.g. in palaeoclimate research. This study evaluates the ability to analyse boron isotopes by laser ablation at levels down to 0.2 ppm in biogenic carbonates as well as in various minerals (e.g., calcit, garnet, cpx, apatite, hematite, quartz, diamond ...) and natural and synthetic glass (NIST, USGS, and MPI-DING). Mounted and polished samples were ablated in a two-volume Helix cell using a RESOlution 193nm Excimer laser coupled to a Thermo-Finnigan Neptune (No. 1, build in 2000). Due to high sensitivity isotope signals were detected using Faraday collectors (1011 Ohm resistors). Analyses were performed as static spots over 25s with diameters of 235 to 7 μm depending on boron concentration, which yield typical 11B signals of about 0.04 (≤ 1ppm; e.g., cherts) to >0.6 V (3wt.%; tourmaline). Therefore, sample amount consumed during analyses range from 1 nanogram to 10 microgram with total analysed B content in the range of 5 to 1000 picogram. For correction of drift and mass fractionation soda-lime glass NIST-612 or NIST-610 were analysed every 30min. The applied method yields for various materials a typical analytical precision and reproducibility (1σ) of the 11B/10B of about 0.5‰ or better at boron concentration of more than 2 ppm. The effect of various parameters such as gas background, surface contamination, cross contamination, spot size, laser energy, and depth drilling will be discussed briefly. However, crucial for in-situ analyse is the evaluation of the accuracy and the influence of the sample matrix on it. Approaches to test this are still hampered by the lack of well-characterized low-B (e.g. <20ppm) reference materiel of different sample matrix. Nevertheless, in contrast to previous studies an effect of sample matrix on the boron isotope ratio was

  15. Possible roles of pH, temperature, and partial dissolution in determining boron concentration and isotopic composition in planktonic foraminifera

    USGS Publications Warehouse

    Wara, M.W.; Delaney, M.L.; Bullen, T.D.; Ravelo, A.C.

    2003-01-01

    We present the first continuous records from 0 to 5 Ma (in 0.333 m.y. integrated time steps) of paired boron/calcium (B/Ca) ratios and boron isotopes (??11B) in the planktonic foraminifera Globogerinoides sacculifer (without sacc) from a site in the western equatorial Pacific Ocean (Ocean Drilling Program Site 806). These measurements, the first made in conjunction with calcification temperature (magnesium/calcium ratios) and average shell mass measurements, indicate that pH is not the sole environmental variable controlling B in planktonic foraminiferal calcite. Our data are consistent with calcification temperature exerting a primary control on B concentration and isotopic composition in planktonic foraminifera. If so, calcification temperature must be taken into account if pH for past oceans and atmospheric pCO2 are to be estimated from B isotope measurements in foraminiferal calcite. Doing so will substantially increase the uncertainty of PH estimates. Although this work was designed as a temporal study, its results define new aspects of calibrating the ??11B paleo-pH tracer. Copyright 2003 by the American Geophysical Union.

  16. 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).

  17. Studies on the isotopic analysis of boron by thermal ionisation mass spectrometry using NaCl for the formation of Na2BO2+ species

    NASA Astrophysics Data System (ADS)

    Rao, R. M.; Parab, A. R.; Sasibhushan, K.; Aggarwal, S. K.

    2008-06-01

    Studies were carried out on the use of NaCl instead of sodium carbonate or sodium hydroxide for the formation of Na2BO2+ ion used for the determination of isotopic composition of boron by TIMS. The addition of mannitol which forms an anionic complex with boron was found to be essential when using NaCl. The investigations show that when NaCl is used, B/Na molar concentration ratio need not be critically adjusted to 1 as required in case of sodium carbonate or sodium hydroxide. The 10B/11B ratio was found to be independent of B/Na molar concentration ratio in the range of 25-0.05. This aspect is extremely useful in carrying out isotopic analysis of B in unknown samples solutions. NIST boron isotopic standard SRM-951 having 10B/11B isotopic ratio of 0.2473 ± 0.0002 was used in these studies and a value of 0.24742 ± 0.00006 (1[sigma]) was obtained.

  18. The atomic weight and isotopic composition of boron and their variation in nature

    SciTech Connect

    Holden, N.E.

    1993-08-01

    The boron isotopic composition and atomic weight value and their variation in nature are reviewed. Questions are raised about the previously recommended value and the uncertainty for the atomic weight. The problem of what constitutes an acceptable range for normal material and what should then be considered geologically exceptional is discussed. Recent measurements make some previous decisions in need of re-evaluation.

  19. Towards absolute laser spectroscopic CO2 isotope ratio measurements

    NASA Astrophysics Data System (ADS)

    Anyangwe Nwaboh, Javis; Werhahn, Olav; Ebert, Volker

    2017-04-01

    Knowledge of isotope composition of carbon dioxide (CO2) in the atmosphere is necessary to identify sources and sinks of this key greenhouse gas. In the last years, laser spectroscopic techniques such as cavity ring-down spectroscopy (CRDS) and tunable diode laser absorption spectroscopy (TDLAS) have been shown to perform accurate isotope ratio measurements for CO2 and other gases like water vapour (H2O) [1,2]. Typically, isotope ratios are reported in literature referring to reference materials provided by e.g. the International Atomic Energy Agency (IAEA). However, there could be some benefit if field deployable absolute isotope ratio measurement methods were developed to address issues such as exhausted reference material like the Pee Dee Belemnite (PDB) standard. Absolute isotope ratio measurements would be particularly important for situations where reference materials do not even exist. Here, we present CRDS and TDLAS-based absolute isotope ratios (13C/12C ) in atmospheric CO2. We demonstrate the capabilities of the used methods by measuring CO2 isotope ratios in gas standards. We compare our results to values reported for the isotope certified gas standards. Guide to the expression of uncertainty in measurement (GUM) compliant uncertainty budgets on the CRDS and TDLAS absolute isotope ratio measurements are presented, and traceability is addressed. We outline the current impediments in realizing high accuracy absolute isotope ratio measurements using laser spectroscopic methods, propose solutions and the way forward. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] B. Kühnreich, S. Wagner, J. C. Habig,·O. Möhler, H. Saathoff, V. Ebert, Appl. Phys. B 119:177-187 (2015). [2] E. Kerstel, L. Gianfrani, Appl. Phys. B 92, 439-449 (2008).

  20. Boron

    USDA-ARS?s Scientific Manuscript database

    Boron is an essential micronutrient element required for plant growth. Boron deficiency is wide-spread in crop plants throughout the world especially in coarse-textured soils in humid areas. Boron toxicity can also occur, especially in arid regions under irrigation. Plants respond directly to the...

  1. Evidence of Northeastern Atlantic Ocean Acidification Recorded by Boron Isotopes on Deep-sea Coral Madrepora oculata

    NASA Astrophysics Data System (ADS)

    Gonzalez-Roubaud, C.; Douville, E.; Bordier, L.; Louvat, P.; Gaillardet, J.; Hall-Spencer, J. M.; Juillet-Leclerc, A.

    2011-12-01

    Ocean acidification is caused by the rising levels of CO2 in the atmosphere since the industrial era. Seawater pH has already decreased 0.1 units in surface waters and will continue to drop as atmospheric CO2 levels increase. Assessing the pH variability during the last decades is essential as survival of calcifying organisms strongly depends on seawater pH. Several studies have shown the potential of boron isotopic composition in tropical corals for reconstructing for sea-surface paleo-pH at low latitudes. For highest latitudes and deeper waters (50-4500 m), cold-water corals are interesting and unique as natural archives not only because they live between 4°C and 12°C under strong currents, recording the parameters of sub-surface or intermediate currents, but also because they build their aragonite skeleton without the photosynthesis process. In order to assess if the seawater acidification has already reached the North Atlantic Ocean at high latitudes, pH reconstruction has been performed on a deep-sea coral Madrepora oculata sample from Rost Reef (67°N, 9°E, 350 m of depth). Boron isotopes have been measured on the Neptune Multi-Collector Inductively Coupled Plasma Mass Spectrometer (MCICP-MS) with direct injection system (d-DIHEN). External reproducibility obtained here for seawater reference NASS-2 was 0.1%. The model age estimates its life-span to 40±3 years (2σ) and the Li/Mg ratio estimates a relative constant seawater temperature during the whole period of growth of the coral (7.0±0.5°C). A drop tendency is observed on boron isotopes, reflecting a potential decrease of seawater pH of approximately 0.06±0.02 pH units during the last 40 years, depending on the isotopic fractionation coefficient employed for calculations. Similarly, seawater acidification rate is 0.0012±0.00015 pH units per year. pH and temperature reconstructions revealed an influence of thermohaline circulation and surface winds on the skeleton geochemistry. Supplementary

  2. 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).

  3. Matrix Effects on Boron Containing Materials due to Laser Ablation Molecular Isotopic Spectrometry (LAMIS)

    NASA Astrophysics Data System (ADS)

    Brown, Staci R.; Akpovo, Charlemagne A.; Martinez, Jorge; Ford, Alan; Herbert, Kenley; Johnson, Lewis

    2014-03-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a spectroscopic technique that is used for the qualitative and quantitative analysis of materials in the liquid, solid, or gas phase. LIBS can also be used for the detection of isotopic shifts in atomic and diatomic species via Laser-Ablation Molecular Isotopic Spectroscopy (LAMIS). However, any additional elements that are entrained into the plasma other than the element of interest, can affect the extent of ablation and quality of spectra and hence, potentially obscure or aid in the relative abundance assessment for a given element. To address the importance of matrix effects, the isotopic analysis of boron obtained from boron oxide (BO) emission originating from different boron-containing compounds, such as boron nitride (BN), boric acid (H3BO3) , and borax (Na2B4O710H2O), via LIBS has been performed here. Each of these materials has different physical properties and elemental composition in order to illustrate possible challenges for the LAMIS method. A calibration-free model similar to that for the original LAMIS work is used to determine properties of the plasma as the matrix is changed. DTRA

  4. Boron isotopes reveal multiple metasomatic events in the mantle beneath the eastern North China Craton

    NASA Astrophysics Data System (ADS)

    Li, Hong-Yan; Zhou, Zhou; Ryan, Jeffrey G.; Wei, Gang-Jian; Xu, Yi-Gang

    2016-12-01

    Linkages inferred between the geochemical heterogeneity of the mantle beneath eastern Eurasia and the stagnant Pacific slab documented geophysically in its mantle transition zone are as yet not clearly characterized. In this paper we report new elemental and isotopic data for boron (B) on a suite of well-characterized Cenozoic basalts (alkali basalts, basanites and nephelinites), with ocean island basalt (OIB)-like trace element signatures from western Shandong of the eastern North China Craton (NCC). Correlations between major elements (e.g., FeOT versus SiO2), trace elements (e.g., CeN/PbN versus BaN/ThN) and radiogenic isotopes (e.g., 206Pb/204Pb versus 87Sr/86Sr) suggest these basalts are derived via the mixing of melts from two mantle components: a fluid mobile element (FME; such as Ba, K, Pb and Sr) enriched component, which is most evident in the alkali basalts, and a FME depleted mantle component that is more evident in the basanites and nephelinites. The alkali basalts in this study have lower B concentrations (1.4-2.2 μg/g) but higher δ11B (-4.9 to -1.4) values than the basanites and nephelinites (B = 2.1-5.0 μg/g; δ11B = -6.9 to -3.9), and all the samples have nearly constant B/Nb ratios between 0.03 and 0.07, similar to the observed range in B/Nb for intraplate lavas. Our high-SiO2 samples have higher δ11B than that of our low SiO2 samples, indicating that the B isotopic differences among our samples do not result from the addition of a continental crustal component in the mantle source, or direct crustal assimilation during the eruption process. The positive B versus Nb correlation suggests the B isotopic compositions of the western Shandong basalts primarily reflect the pre-eruptive compositions of their mantle sources. Correlations among B, Nd and Sr isotope signatures of the western Shandong basalts differ from those among basalts from plume settings (e.g., Azores and Hawaii), and are inconsistent with models suggesting single-step metasomatic

  5. Symbiodinium Clade Affects Coral Skeletal Isotopic Ratio

    NASA Astrophysics Data System (ADS)

    Carilli, J.; Charles, C. D.; Garren, M.; McField, M.; Norris, R. D.

    2011-12-01

    The influence of different physiologies of Symbiodinium dinoflagellate symbiont clades on the skeletal chemistry of associated coral hosts has not previously been investigated. This is an important issue because coral skeletons are routinely used for tropical paleoclimatic reconstructions. We analyzed coral skeletal samples collected simultaneously from neighboring colonies off Belize and found that those harboring different clades of Symbiodinium displayed significantly different skeletal oxygen isotopic compositions. We also found evidence for mean shifts in skeletal oxygen isotopic composition after coral bleaching (the loss and potential exchange of symbionts) in two of four longer coral cores from the Mesoamerican Reef, though all experienced similar climatic conditions. Thus, we suggest that symbiont clade identity leaves a signature in the coral skeletal archive and that this influence must be considered for quantitative environmental reconstruction. In addition, we suggest that the skeletal isotopic signature may be used to identify changes in the dominant symbiont clade that have occurred in the past, to identify how common and widespread this phenomenon is--a potential adaptation to climate change.

  6. MIR hollow waveguide (HWG) isotope ratio analyzer for environmental applications

    NASA Astrophysics Data System (ADS)

    Wang, Zhenyou; Zhuang, Yan; Deev, Andrei; Wu, Sheng

    2017-05-01

    An advanced commercial Mid-InfraRed Isotope Ratio (IR2) analyzer was developed in Arrow Grand Technologies based on hollow waveguide (HWG) as the sample tube. The stable carbon isotope ratio, i.e. δ13C, was obtained by measuring the selected CO2 absorption peaks in the MIR. Combined with a GC and a combustor, it has been successfully employed to measure compound specific δ13C isotope ratios in the field. By using both the 1- pass HWG and 5-path HWG, we are able to measure δ13C isotope ratio at a broad CO2 concentration of 300 ppm-37,500 ppm. Here, we demonstrate its applications in environmental studies. The δ13C isotope ratio and concentration of CO2 exhaled by soil samples was measured in real time with the isotope analyzer. The concentration was found to change with the time. We also convert the Dissolved Inorganic Carbon (DIC) into CO2, and then measure the δ13C isotope ratio with an accuracy of better than 0.3 ‰ (1 σ) with a 6 min test time and 1 ml sample usage. Tap water, NaHCO3 solvent, coca, and even beer were tested. Lastly, the 13C isotope ratio of CO2 exhaled by human beings was obtained <10 seconds after simply blowing the exhaled CO2 into a tube with an accuracy of 0.5‰ (1 σ) without sample preconditioning. In summary, a commercial HWG isotope analyzer was demonstrated to be able to perform environmental and health studies with a high accuracy ( 0.3 ‰/Hz1/2 1 σ), fast sampling rate (up to 10 Hz), low sample consumption ( 1 ml), and broad CO2 concentration range (300 ppm-37,500 ppm).

  7. 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.

  8. Recycling of subducted crustal components into carbonatite melts revealed by boron isotopes

    NASA Astrophysics Data System (ADS)

    Hulett, Samuel R. W.; Simonetti, Antonio; Rasbury, E. Troy; Hemming, N. Gary

    2016-12-01

    The global boron geochemical cycle is closely linked to recycling of geologic material via subduction processes that have occurred over billions of years of Earth’s history. The origin of carbonatites, unique melts derived from carbon-rich and carbonate-rich regions of the upper mantle, has been linked to a variety of mantle-related processes, including subduction and plume-lithosphere interaction. Here we present boron isotope (δ11B) compositions for carbonatites from locations worldwide that span a wide range of emplacement ages (between ~40 and ~2,600 Ma). Hence, they provide insight into the temporal evolution of their mantle sources for ~2.6 billion years of Earth’s history. Boron isotope values are highly variable and range between -8.6‰ and +5.5‰, with all of the young (<300 Ma) carbonatites characterized by more positive δ11B values (>-4.0‰), whereas most of the older carbonatite samples record lower B isotope values. Given the δ11B value for asthenospheric mantle of -7 +/- 1‰, the B isotope compositions for young carbonatites require the involvement of an enriched (crustal) component. Recycled crustal components may be sampled by carbonatite melts associated with mantle plume activity coincident with major tectonic events, and linked to past episodes of significant subduction associated with supercontinent formation.

  9. 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

  10. 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.

  11. Synthetic isotope mixtures for the calibration of isotope amount ratio measurements of carbon

    NASA Astrophysics Data System (ADS)

    Russe, K.; Valkiers, S.; Taylor, P. D. P.

    2004-07-01

    Synthetic isotope mixtures for the calibration of carbon isotope amount ratio measurements have been prepared by mixing carbon tetrafluoride highly enriched in 13C with carbon tetrafluoride depleted in 13C. Mixing procedures based on volumetry and gravimetry are described. The mixtures served as primary measurement standards for the calibration of isotope amount ratio measurements of the Isotopic Reference Materials PEF1, NBS22 and USGS24. Thus SI-traceable measurements of absolute carbon isotope amount ratios have been performed for the first time without any hypothesis needed for a correction of oxygen isotope abundances, such as is the case for measurements on carbon dioxide. As a result, "absolute" carbon isotope amount ratios determined via carbon tetrafluoride have smaller uncertainties than those published for carbon dioxide. From the measurements of the Reference Materials concerned, the absolute carbon isotope amount ratio of Vienna Pee Dee Belemnite (VPDB)--the hypothetical material upon which the scale for relative carbon isotope ratio measurements is based--was calculated to be R13(VPDB) = (11 101 +/- 16) × 10-6.

  12. 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.

  13. Copper and zinc isotope ratios in human bone and enamel.

    PubMed

    Jaouen, Klervia; Herrscher, Estelle; Balter, Vincent

    2017-03-01

    Here, we report Cu and Zn isotope ratios of bones and teeth of French people from various historical periods with the aim to understand how Cu and Zn isotope ratios of bone, a tissue that is continuously remodeled throughout life but that is prone to post-mortem diagenesis, compare with that of tooth enamel, a tissue that forms once during childhood but that is more resistant to diagenesis. Specifically, we examine (1) the potential existence of sex-related differences in the Cu isotope ratios (represented as δ(65) Cu) in the tooth enamel of identified men and women, and (2) a decrease of Zn isotope delta ratios (represented as δ(66) Zn) related to the increase of meat and fish consumption during the 20(th) century. Four series of material were studied: the archeological population of Saint-Laurent de Grenoble (17(th) -18(th) centuries AD), an anatomical collection of skulls (19(th) century AD), a contemporary anatomical collection of bones never buried, and contemporary teeth samples. The metals were purified by liquid chromatography and their isotopic ratios measured by means of multicollector inductively coupled plasma mass spectrometry. We describe a clear offset between bone and tooth enamel for Zn isotope ratios, as previously observed in animals. There is a similar offset for Cu isotope ratios. We did not observe any difference between the δ(65) Cu values of men and women when looking at dental enamel. For the contemporary samples, the δ(66) Zn values of bioapatite decreased, which might be explained by the increase of animal product consumption among the French people during this period, notably when the access to seafood became widespread. Our study demonstrates that the Cu and Zn isotope compositions of dental enamel are promising tools for childhood diet reconstruction. Meanwhile, the Cu isotope ratio of tooth enamel is unlikely to be useful for the identification of biological sex, even in the case of populations with early menarche. Further works

  14. Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals

    NASA Astrophysics Data System (ADS)

    Farmer, Jesse R.; Hönisch, Bärbel; Robinson, Laura F.; Hill, Tessa M.

    2015-04-01

    The ocean is currently absorbing excess carbon from anthropogenic emissions, leading to reduced seawater-pH (termed 'ocean acidification'). Instrumental records of ocean acidification are unavailable from well-ventilated areas of the deep ocean, necessitating proxy records to improve spatio-temporal understanding on the rate and magnitude of deep ocean acidification. Here we investigate boron, carbon, and oxygen isotopes on live-collected deep-sea bamboo corals (genus Keratoisis) from a pHtot range of 7.5-8.1. These analyses are used to explore the potential for using bamboo coral skeletons as archives of past deep-sea pH and to trace anthropogenic acidification in the subsurface North Atlantic Ocean (850-2000 m water depth). Boron isotope ratios of the most recently secreted calcite of bamboo coral skeletons are close to the calculated isotopic composition of borate anion in seawater (δ11Bborate) for North Atlantic corals, and 1-2‰ higher than δ11Bborate for Pacific corals. Within individual coral skeletons, carbon and oxygen isotopes correlate positively and linearly, a feature associated with vital effects during coral calcification. δ11B variability of 0.5-2‰ is observed within single specimens, which exceeds the expected anthropogenic trend in modern North Atlantic corals. δ11B values are generally elevated in Pacific corals relative to δ11Bborate, which may reflect pH-driven physiological processes aiding coral calcification in environments unfavorable for calcite precipitation. Elevated δ11B values are also observed proximal to the central axis in multiple Atlantic and Pacific specimens, relative to δ11Bborate, which might reflect ontogenetic variability in calcification rates. Although the observed boron isotope variability is too large to resolve the present anthropogenic ocean acidification signal at the studied depths in the North Atlantic (∼0.03-0.07 pH units), pH changes ⩾0.1 units might still be reconstructed using δ11B measurements in

  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. Boron isotope composition of geothermal fluids and borate minerals from salar deposits (central Andes/NW Argentina)

    NASA Astrophysics Data System (ADS)

    Kasemann, Simone A.; Meixner, Anette; Erzinger, Jörg; Viramonte, José G.; Alonso, Ricardo N.; Franz, Gerhard

    2004-06-01

    We have measured the boron concentration and isotope composition of regionally expansive borate deposits and geothermal fluids from the Cenozoic geothermal system of the Argentine Puna Plateau in the central Andes. The borate minerals borax, colemanite, hydroboracite, inderite, inyoite, kernite, teruggite, tincalconite, and ulexite span a wide range of δ11B values from -29.5 to -0.3‰, whereas fluids cover a range from -18.3 to 0.7‰. The data from recent coexisting borate minerals and fluids allow for the calculation of the isotope composition of the ancient mineralizing fluids and thus for the constraint of the isotope composition of the source rocks sampled by the fluids. The boron isotope composition of ancient mineralizing fluids appears uniform throughout the section of precipitates at a given locality and similar to values obtained from recent thermal fluids. These findings support models that suggest uniform and stable climatic, magmatic, and tectonic conditions during the past 8 million years in this part of the central Andes. Boron in fluids is derived from different sources, depending on the drainage system and local country rocks. One significant boron source is the Paleozoic basement, which has a whole-rock isotopic composition of δ11B=-8.9±2.2‰ (1 SD); another important boron contribution comes from Neogene-Pleistocene ignimbrites ( δ11B=-3.8±2.8‰, 1 SD). Cenozoic andesites and Mesozoic limestones ( δ11B≤+8‰) provide a potential third boron source.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Stable Isotope Ratios and Forensic Analysis of Microorganisms▿

    PubMed Central

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

    2007-01-01

    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 microbial forensics, using as a database the carbon, nitrogen, oxygen, and hydrogen stable isotope ratios of 247 separate cultures of Bacillus 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 variations 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. PMID:17468274

  2. 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.

  3. Influence of magmatic volatiles on boron isotope compositions in vent fluids from the Eastern Manus Basin, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Wilckens, F. K.; Kasemann, S.; Bach, W.; Reeves, E. P.; Meixner, A.; Seewald, J.

    2016-12-01

    In this study we present boron (B), lithium (Li) and strontium (Sr) concentrations and isotopic composition of submarine hydrothermal fluids collected in 2006 and 2011 from PACMANUS, DESMOS and SuSu Knolls vent fields located in the Eastern Manus Basin [1,2]. Hydrothermal vent fluids within the Eastern Manus Basin range from high-temperature black smoker fluids to low-temperature diffuse fluids and acid-sulfate fluids. In general, the different fluid types show variable water-rock ratios during water-rock interaction and different inputs of magmatic volatiles. End-member black smoker fluids, which have in general high temperatures (mostly higher than 280°C) and pH values higher than 2 (measured at 25°C) are characterized by low δ7Li values (3.9 to 5.9‰) and 87Sr/86Sr ratios (0.704 to 0.705) similar to the values for island arc basalts. These results suggest low water-rock ratios during hydrothermal circulation. B concentrations and isotopic compositions in these fluids range from 1.0 to 2.6μM and 13 to 20‰, respectively. These data match with other vent fluids from island arc settings in the Western Pacific and plot in a B versus δ11B diagram on a two-component mixing line between seawater and island arc basalts [3]. Sr and Li isotopic composition of white smoker and acid-sulfate fluids overlap generally with the isotopic ratios for the black smoker fluids. However, in some fluids Sr isotope ratios are up to 0.709 near seawater composition suggesting higher water-rock ratios during water-rock interaction. B concentrations and isotope ratios in the white smoker and acid-sulfate fluids range from 0.6 to 2.2μM and 9 to 16‰, respectively which are lower compared with the values of black smoker fluids. In addition, these fluids do not fit on the mixing line between seawater and island arc basalt, and define another mixing trend in a B versus δ11B diagram. To explain this contradictory trend, a third mixing endmember is required that shifts B concentrations

  4. Boron contents and isotopic compositions of the hydrothermally altered oceanic crust from the Troodos ophiolite, Cyprus

    NASA Astrophysics Data System (ADS)

    Matsukura, S.; Yamaoka, K.; Ishikawa, T.; Kawahata, H.

    2010-12-01

    The boron contents and isotopic compositions were determined for the hydrothermally altered oceanic crust through the Troodos ophiolite. The samples were represented by the International Crustal Research Drilling Group (ICRDG) drill-Holes CY1 (479m), CY2A (689m), CY4 (2263m), and selected outcrops along the Akaki river. Hole CY1 was composed upper and lower pillow lava, CY4 constituted sheeted dike complex and gabbro section, and the samples along Akaki river formed from pillow lava to sheeted dike complex. Hole CY2A was composed pillow lava and sheeted dike, drilled near Agrokipia ‘B’ deposit a stockwork type which completely enclosed within the lower pillow lava. The goal of this study is to understand the Boron geochemistry during hydrothermal alteration of the oceanic crust including hydrothermal ore deposit as Agrokipia ‘B’. The average boron contents of each sequence from Troodos ophiolite were pillow lava (63.2ppm), sheeted dike complex (4.5ppm), gabbro section (1.6ppm). But then, those of Oman ophiolite were 7.9ppm, 5.3ppm, 1.7ppm (Yamaoka et al., 2010 submitted). Thus, both of these ophiolites, the vertical profile of boron content decreased with depth, also the boron contents were much richer than fresh-MORB (0.5ppm) (Spivack and Edmond, 1987; Chaussidon and Jambon, 1994). This indicates boron rich of the altered oceanic crust were derived from seawater. And sheeted dike complex and gabbro section were similar value relatively, but pillow lava differed widely. These results may represent the difference of length being submarine, because these ophiolites were generated in deep water of the Tethys sea about 90Ma (Late Cretaceous) (Tilton et al., 1981; Mukasa and Ludden, 1987), and Oman ophiolite was obducted about 70Ma (Lanphere, 1981) but Troodos ophiolite uplifted about 10Ma (Middle Miocene) (Robertson and Woodcock, 1979).

  5. 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.

  6. 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.

  7. Crystallographic control on the boron isotope paleo-pH proxy

    NASA Astrophysics Data System (ADS)

    Noireaux, J.; Mavromatis, V.; Gaillardet, J.; Schott, J.; Montouillout, V.; Louvat, P.; Rollion-Bard, C.; Neuville, D. R.

    2015-11-01

    When using the boron isotopic composition (δ11B) of marine carbonates as a seawater pH proxy, it is assumed that only the tetrahedral borate ion is incorporated into the growing carbonate crystals and that no boron isotope fractionation occurs during uptake. However, the δ11B of the calcium carbonate from most modern foraminifera shells or corals skeletons is not the same as the δ11B of seawater borate, which depends on pH, an observation commonly attributed to vital effects. In this study, we combined previously published high-field 11B MAS NMR and new δ11B measurements on the same synthetic calcite and aragonite samples precipitated inorganically under controlled environments to avoid vital effects. Our results indicate that the main controlling factors of δ11B are the solution pH and the mineralogy of the precipitated carbonate mineral, whereas the aqueous boron concentration of the solution, CaCO3 precipitation rate and the presence or absence of growth seeds all appear to have negligible influence. In aragonite, the NMR data show that boron coordination is tetrahedral (BO4), in addition, its δ11B is equal to that of aqueous borate, thus confirming the paleo-pH hypothesis. In contrast, both trigonal BO3 and tetrahedral BO4 are present in calcite, and its δ11B values are higher than that of aqueous borate and are less sensitive to solution pH variations compared to δ11B in aragonite. These observations are interpreted in calcite as a reflection of the incorporation of decreasing amounts of boric acid with increasing pH. Moreover, the fraction of BO3 measured by NMR in calcite is higher than that inferred from δ11B which indicates a coordination change from BO4 to BO3 upon boron incorporation in the solid. Overall, this study shows that although the observed differences in δ11B between inorganic and biological aragonite are compatible with a pH increase at calcification sites, the B speciation and isotope composition of biological calcites call for a

  8. Boron

    MedlinePlus

    ... body handles other minerals such as magnesium and phosphorus. It also seems to increase estrogen levels in ... happens in men.PhosphorusSupplemental boron might reduce blood phosphorus levels in some people.

  9. 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.

  10. 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).

  11. 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.

  12. 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.

  13. Boron isotope variations in geothermal systems on Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Purnomo, Budi Joko; Pichler, Thomas; You, Chen-Feng

    2016-02-01

    This paper presents δ11B data for hot springs, hot acid crater lakes, geothermal brines and a steam vent from Java, Indonesia. The processes that produce a large range of the δ11B values were investigated, including the possible input of seawater as well as the contrast δ11B compositions of acid sulfate and acid chloride crater lakes. The δ11B values of hot springs ranged from - 2.4 to + 28.7‰ and acid crater lakes ranged from + 0.6 to + 34.9‰. The δ11B and Cl/B values in waters from the Parangtritis and Krakal geothermal systems confirmed seawater input. The δ11B values of acid sulfate crater lakes ranged from + 5.5 to + 34.9‰ and were higher than the δ11B of + 0.6‰ of the acid chloride crater lake. The heavier δ11B in the acid sulfate crater lakes was caused by a combination of vapor phase addition and further enrichment due to evaporation and B adsorption onto clay minerals. In contrast, the light δ11B of the acid chloride crater lake was a result of acid water-rocks interaction. The correlations of δ11B composition with δ18O and δ2H indicated that the B isotope corresponded to their groundwater mixing sources, but not for J21 (Segaran) and J48 (Cikundul) that underwent 11B isotope enrichment by B adsorption into minerals.

  14. Boron isotopes in deep-sea bamboo corals: pH, vital effects and environmental factors

    NASA Astrophysics Data System (ADS)

    Farmer, J. R.; Hoenisch, B.; Hill, T. M.; LaVigne, M.; Robinson, L. F.

    2011-12-01

    Deep-sea corals are an intriguing archive for reconstructing deep-ocean environmental conditions, in particular with regard to anthropogenic climate change and ocean acidification. However, previous research in deep-sea aragonitic scleractinian corals observed heterogeneity in their geochemical composition that greatly exceeded the magnitude of variability expected from environmental conditions. Here we investigate the boron isotopic composition (δ11B) and B/Ca ratios of the calcitic gorgonian bamboo coral Keratoisis sp. (family Isididae) as potential indicators of seawater-pH at depth. Initial results from a specimen collected alive on Little Joe Seamount, CA (2136m depth) show that the δ11B of surface calcite is within the expected range of aqueous borate-δ11B, based on seawater pH, temperature, pressure and salinity. A radial cross section through an ~5 cm thick internode reveals largely homogeneous δ11B. However, in the centermost 0.5 cm of calcite growth adjacent to the axial core of the coral, a ~2% increase in δ11B corresponds with disequilibrium depletions in δ13C and δ18O, consistent with hypotheses for different growth modes of central calcite perhaps as a result of active calcite deposition along the axial core. Aside from this central region, the geochemical homogeneity and good agreement between coral surface δ11B and seawater borate δ11B suggests that bamboo corals may record deep-ocean carbon chemistry and thus pH. The cosmopolitan distribution of Keratoisis sp. in both living and fossil deep-sea coral communities thus potentially presents the opportunity to reconstruct recent and Holocene deep-water pH at high resolution.

  15. 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.

  16. 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.

  17. An Alternative Explanation of the Varying Boron-to-carbon Ratio in Galactic Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Eichler, David

    2017-06-01

    It is suggested that the decline with energy of the boron-to-carbon abundance ratio in Galactic cosmic rays is due, in part, to a correlation between the maximum energy attainable by shock acceleration in a given region of the Galactic disk and the grammage traversed before escape. In this case the energy dependence of the escape rate from the Galaxy may be less than previously thought and the spectrum of antiprotons becomes easier to understand.

  18. Application of 10(13) ohm Faraday cup current amplifiers for boron isotopic analyses by solution mode and laser ablation MC-ICP-MS.

    PubMed

    Lloyd, Nicholas S; Sadekov, Aleksey Yu; Misra, Sambuddha

    2017-10-09

    Boron isotope ratios (δ(11) B values) are used as a proxy for seawater paleo-pH, amongst several other applications. The analytical precision can be limited by the detection of low intensity ion beams from limited sample amounts. High-gain amplifiers offer improvements in signal/noise ratio and can be used to increase measurement precision and reduce sample amounts. 10(13) ohm amplifier technology has previously been applied to several radiogenic systems, but has thus far not been applied to non-traditional stable isotopes. Here we apply 10(13) ohm amplifier technology for the measurement of boron isotope ratios using solution mode MC-ICP-MS and laser ablation mode (LA-) MC-ICP-MS techniques. Precision is shown for reference materials as well as for low-volume foraminifera samples. The baseline uncertainty for a 0.1 pA (10) B ion beam is reduced to < 0.1 ‰ for a typical measurement period. The external precision is better than 0.2 ‰ (2SD) for δ(11) B measurements for solution samples containing as little as 0.8 ng total boron. For in-situ microanalyses with LA-MC-ICP-MS, the external precision of (11) B/(10) B from an in-house calcite standard was 1 ‰ (2SD) for individual spot analyses, and 0.3 ‰ for the mean of ≥ 10 replicate spot analyses. 10(13) ohm amplifier technology is demonstrated to offer advantages for the determination of δ(11) B values by both MC-ICP-MS and LA-MC-ICP-MS for small samples of biogenic carbonates, such as foraminifera shells. 10(13) ohm amplifier technology will also be of benefit to other non-traditional stable isotope measurements. This article is protected by copyright. All rights reserved.

  19. 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.

  20. 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.

  1. 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.

  2. Boron isotope study of high-pressure metamorphic rocks from Syros (Greece) by secondary ion mass spectrometry (SIMS)

    NASA Astrophysics Data System (ADS)

    Marschall, H.; Altherr, R.; Ludwig, T.; Kalt, A.

    2003-04-01

    The Heidelberg Cameca ims-3f ion probe has been modified in order to measure δ11B values with a precision of ±1 ppm (2σ) in tourmaline, ±2 ppm in phengite (≈100 μg/g B), and ±4 ppm in other minerals (2--10 μg/g B). Three tourmaline standards (98144 elbaite, 112566 schorl and 108796 dravite; [1]) of different chemical compositions were used to correct for instrumental mass fractionation. This newly established equipment has been used to determine the isotopic ratios of boron (11B/10B) in minerals of Eocene high-pressure rocks from the island of Syros, Greece, for which metamorphic peak conditions of ˜470^oC and 1.5 GPa have been estimated [e.g. 2]. The rocks examined represent different parts of former oceanic crust and occur as eclogites, mafic blueschists, metagabbros, talc-chlorite-actinolite schists or serpentinites. Two types of tourmaline were recognized within the rocks [3]. Type I are small grains (100 μm) with dravite cores and schorl rims, forming inclusions in garnet, glaucophane or phengite. Type II are large grains (10 mm) with very weak zonations occurring within reaction zones between eclogites and serpentinites. Type I shows strong isotopic zonations with light cores of δ11B = -4 ppm and heavy rims of δ11B = +8 ppm. Despite their large grain size, Type II tourmalines show very homogenous isotopic compositions, varying randomly by ±1 ppm over whole grains. Isotopic composition of type II tourmalines were found to be extremely heavy and range from +19 ppm to +22 ppm among different samples. Preliminary results on coexisting phengite, chlorite and glaucophane show significant fractionation between tourmaline and other silicates, with the latter being more than 10 ppm lighter. The heavy isotopic composition of type II tourmaline, formed at depth of approx. 50 km, reflects boron-rich fluids that migrated through the rocks during subduction and early exhumation. They are direct evidence for very high d11B values (>+20 ppm) of subduction

  3. Isotope shifts in beryllium-, boron-, carbon-, and nitrogen-like ions from relativistic configuration interaction calculations

    SciTech Connect

    Nazé, C.; Verdebout, S.; Godefroid, M.

    2014-09-15

    Energy levels, normal and specific mass shift parameters as well as electronic densities at the nucleus are reported for numerous states along the beryllium, boron, carbon, and nitrogen isoelectronic sequences. Combined with nuclear data, these electronic parameters can be used to determine values of level and transition isotope shifts. The calculation of the electronic parameters is done using first-order perturbation theory with relativistic configuration interaction wavefunctions that account for valence, core–valence, and core–core correlation effects as zero-order functions. Results are compared with experimental and other theoretical values, when available.

  4. Boron-isotope systematics of Halmahera arc (Indonesia) lava: Evidence for involvement of the subducted slab

    SciTech Connect

    Palmer, M.R. )

    1991-03-01

    Dehydration of sediments and oceanic crust within the subducting slab at convergent plate margins is probably a ubiquitous feature. This leads to fractionation of elements between fluids and solids so that the slab-derived component of island-arc lavas is modified from the originally subducted material. Sediments and altered oceanic crust are enriched in boron and cesium relative to uncontaminated mantle products, and these elements are highly mobile during fluid-rock interaction. The combination of B-isotope systematics and Cs concentrations in lavas from the Halmahera arc (Indonesia) suggests that they have been influenced by fluids derived from dehydration and/or melting of the subducted slab.

  5. Boron-isotope systematics of Halmahera arc (Indonesia) lavas: Evidence for involvement of the subducted slab

    NASA Astrophysics Data System (ADS)

    Palmer, M. R.

    1991-03-01

    Dehydration of sediments and oceanic crust within the subducting slab at convergent plate margins is probably a ubiquitous feature. This leads to fractionation of elements between fluids and solids so that the slab-derived component of island-arc lavas is modified from the originally subducted material. Sediments and altered oceanic crust are enriched in boron and cesium relative to uncontaminated mantle products, and these elements are highly mobile during fluid-rock interaction. The combination of B-isotope systematics and Cs concentrations in lavas from the Halmahera arc (Indonesia) suggests that they have been influenced by fluids derived from dehydration and/or melting of the subducted slab.

  6. 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

  7. Sample matrix effects on measured carbon and oxygen isotope ratios during continuous-flow isotope-ratio mass spectrometry.

    PubMed

    Levitt, Nicholas Paul

    2014-11-15

    Continuous-flow isotope-ratio mass spectrometry (CF-IRMS) is frequently used to analyze CO2 found in media such as air, breath, and soil pore space gas with the aid of a sample preparation and transfer device such as a Gasbench II. This study investigated the effect that matrices other than helium (He) have on the measured δ(13)C and δ(18)O isotope ratios of CO2. Identical CO2 was added to sample vials with matrices of pure He, pure N2, or a 21:79 mixture of O2/N2 and analyzed by a ThermoFinnigan Delta(Plus) XP isotope-ratio mass spectrometer coupled to a ThermoFinnigan Gasbench II. Variables such as CO2 concentration, sample analysis sequence, and sample matrix removal ('blanking') through manipulation of an injection and dilution open split were tested to identify systematic isotope ratio offsets between the different matrix types. The process of blanking induced a δ(13)C and δ(18)O offset of ≤0.2‰ between otherwise identical populations of CO2 samples in He. The (13)C/(12)C and (18)O/(16)O isotope ratios of CO2 sampled from pure N2 or a mixture of O2/N2 were found to be within 0.1 to 0.2‰ of those of an identical CO2 sampled from a He matrix when N2 or O2/N2 was removed prior to transport to the mass spectrometer. The measured oxygen isotope ratios of CO2 sampled from N2 and O2/N2 varied by as much as 0.6‰ and 4‰, respectively, if matrix gas was not removed prior to ionization. Sampling CO2 from matrices similar to air does not significantly affect the measured (13)C/(12)C and (18)O/(16)O isotope ratios of CO2 when a gas-handling procedure that includes the removal of matrix gas is utilized. This procedure is much preferable to introducing matrix gas and potentially isobaric interference to the ion source. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Environmental controls on the boron and strontium isotopic composition of aragonite shell material of cultured Arctica islandica

    NASA Astrophysics Data System (ADS)

    Liu, Y.-W.; Aciego, S. M.; Wanamaker, A. D., Jr.

    2015-06-01

    Ocean acidification, the decrease in ocean pH associated with increasing atmospheric CO2, is likely to impact marine organisms, particularly those that produce carbonate skeletons or shells. Therefore, it is important to investigate how environmental factors (seawater pH, temperature and salinity) influence the chemical compositions in biogenic carbonates. In this study we report the first high-resolution strontium (87Sr / 86Sr and δ88 / 86Sr) and boron (δ11B) isotopic values in the aragonite shell of cultured Arctica islandica (A. islandica). The 87Sr / 86Sr ratios from both tank water and shell samples show ratios nearly identical to the open ocean, which suggests that the shell material reflects ambient ocean chemistry without terrestrial influence. The 84Sr-87Sr double-spike-resolved shell δ88 / 86Sr and Sr concentration data show no resolvable change throughout the culture period and reflect no theoretical kinetic mass fractionation throughout the experiment despite a temperature change of more than 15 °C. The δ11B records from the experiment show at least a 5‰ increase through the 29-week culture season (January 2010-August 2010), with low values from the beginning to week 19 and higher values thereafter. The larger range in δ11B in this experiment compared to predictions based on other carbonate organisms (2-3‰) suggests that a species-specific fractionation factor may be required. A significant correlation between the ΔpH (pHshell - pHsw) and seawater pH (pHsw) was observed (R2 = 0.35), where the pHshell is the calcification pH of the shell calculated from boron isotopic composition. This negative correlation suggests that A. islandica partly regulates the pH of the extrapallial fluid. However, this proposed mechanism only explains approximately 35% of the variance in the δ11B data. Instead, a rapid rise in δ11B of the shell material after week 19, during the summer, suggests that the boron uptake changes when a thermal threshold of > 13 °C is

  9. 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.

  10. On Poisson's ratio for metal matrix composite laminates. [aluminum boron composites

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.; Shuart, M. J.

    1978-01-01

    The definition of Poisson's ratio for nonlinear behavior of metal matrix composite laminates is discussed and experimental results for tensile and compressive loading of five different boron-aluminum laminates are presented. It is shown that there may be considerable difference in the value of Poisson's ratio as defined by a total strain or an incremental strain definition. It is argued that the incremental definition is more appropriate for nonlinear material behavior. Results from a (0) laminate indicate that the incremental definition provides a precursor to failure which is not evident if the total strain definition is used.

  11. NUSIMEP-7: uranium isotope amount ratios in uranium particles.

    PubMed

    Truyens, J; Stefaniak, E A; Aregbe, Y

    2013-11-01

    The Institute for Reference Materials and Measurements (IRMM) has extensive experience in the development of isotopic reference materials and the organization of interlaboratory comparisons (ILC) for nuclear measurements in compliance with the respective international guidelines (ISO Guide 34:2009 and ISO/IEC 17043:2010). The IRMM Nuclear Signatures Interlaboratory Measurement Evaluation Program (NUSIMEP) is an external quality control program with the objective of providing materials for measurements of trace amounts of nuclear materials in environmental matrices. Measurements of the isotopic ratios of the elements uranium and plutonium in small amounts, typical of those found in environmental samples, are required for nuclear safeguards and security, for the control of environmental contamination and for the detection of nuclear proliferation. The measurement results of participants in NUSIMEP are evaluated according to international guidelines in comparison to independent external certified reference values with demonstrated metrological traceability and uncertainty. NUSIMEP-7 focused on measurements of uranium isotope amount ratios in uranium particles aiming to support European Safeguards Directorate General for Energy (DG ENER), the International Atomic Energy Agency's (IAEA) network of analytical laboratories for environmental sampling (NWAL) and laboratories in the field of particle analysis. Each participant was provided two certified test samples: one with single and one with double isotopic enrichment. These NUSIMEP test samples were prepared by controlled hydrolysis of certified uranium hexafluoride in a specially designed aerosol deposition chamber at IRMM. Laboratories participating in NUSIMEP-7 received the test samples of uranium particles on two graphite disks with undisclosed isotopic ratio values n((234)U)/n((238)U), n((235)U)/n((238)U) and n((236)U)/n((238)U). The uranium isotope ratios had to be measured using their routine analytical

  12. Si Isotopic Ratios in Mainstream Presolar SIC Grains Revisited

    NASA Astrophysics Data System (ADS)

    Lugaro, Maria; Zinner, Ernst; Gallino, Roberto; Amari, Sachiko

    1999-12-01

    Although mainstream SiC grains, the major group of presolar SiC grains found in meteorites, are believed to have originated in the expanding envelope of asymptotic giant branch (AGB) stars during their late carbon-rich phases, their Si isotopic ratios show a distribution that cannot be explained by nucleosynthesis in this kind of star. Previously, this distribution has been interpreted to be the result of contributions from many AGB stars of different ages whose initial Si isotopic ratios vary owing to the Galactic chemical evolution of the Si isotopes. This paper presents a new interpretation based on local heterogeneities of the Si isotopes in the interstellar medium at the time the parent stars of the mainstream grains were born. Recently, several authors have presented inhomogeneous chemical evolution models of the Galactic disk in order to account for the well-known evidence that F and G dwarfs of similar age show an intrinsic scatter in their elemental abundances. First we report new calculations of the s-process nucleosynthesis of the Si and Ti isotopes in four AGB models (1.5, 3, and 5 Msolar with Z=0.02; 3 Msolar with Z=0.006). These calculations are based on the release of neutrons in the He intershell by the 13C source during the interpulse periods followed by a second small burst of neutrons released in the convective thermal pulse by the marginal activation of the 22Ne source. In the 1.5 and 3 Msolar models with solar metallicity the predicted shifts of the Si isotopic ratios in the stars' envelope are much smaller (<30‰ for the 29Si/28Si ratio and <40‰ for the 30Si/28Si ratio; the two ratios are normalized to solar) than the range observed in the mainstream grains (up to 180‰). Isotopic shifts are of the same order as in the SiC grains for the 5 Msolar and Z=0.006 models, but the slope of the 29Si/28Si versus 30Si/28Si correlation line is much smaller than that of the grains. We also show that none of the models can reproduce the correlations

  13. 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.

  14. Direct measurement of the boron isotope fractionation factor: Reducing the uncertainty in reconstructing ocean paleo-pH

    NASA Astrophysics Data System (ADS)

    Nir, Oded; Vengosh, Avner; Harkness, Jennifer S.; Dwyer, Gary S.; Lahav, Ori

    2015-03-01

    The boron isotopic composition of calcium carbonate skeletons is a promising proxy method for reconstructing paleo-ocean pH and atmospheric CO2 from the geological record. Although the boron isotope methodology has been used extensively over the past two decades to determine ancient ocean-pH, the actual value of the boron isotope fractionation factor (εB) between the two main dissolved boron species, 11B(OH)3 and 10B(OH)-4, has remained uncertain. Initially, εB values were theoretically computed from vibrational frequencies of boron species, resulting in a value of ∼ 19 ‰. Later, spectrophotometric pH measurements on artificial seawater suggested a higher value of ∼ 27 ‰. A few independent theoretical models also pointed to a higher εB value. Here we provide, for the first time, an independent empirical fractionation factor (εB = 26.0 ± 1.0 ‰ ; 25 °C), determined by direct measurements of B(OH)3 in seawater and other solutions. Boric acid was isolated by preferential passage through a reverse osmosis membrane under controlled pH conditions. We further demonstrate that applying the Pitzer ion-interaction approach, combined with ion-pairing calculations, results in a more accurate determination of species distribution in aquatic solutions of different chemical composition, relative to the traditional two-species boron-system approach. We show that using the revised approach reduces both the error in simulating ancient atmospheric CO2 (by up to 21%) and the overall uncertainty of applying boron isotopes for paleo-pH reconstruction. Combined, this revised methodology lays the foundation for a more accurate determination of ocean paleo-pH through time.

  15. 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).

  16. 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)

  17. Investigating Carbonate System Perturbations across the Cretaceous-Palaeogene Transition using Boron Isotopes in Planktonic Foraminifera.

    NASA Astrophysics Data System (ADS)

    Henehan, M. J.; Hull, P. M.; Planavsky, N. J.; Huber, B. T.; Thomas, E.

    2014-12-01

    The interval spanning the latest Maastrichtian to the early Palaeocene has great potential in helping to elucidate the stabilising mechanisms on the Earth's carbonate system on both long and very short geological timescales, from the geologically-instantaneous production of sulphate-rich aerosols and nitrogen oxides from the K-Pg bolide impact to the relatively more gradual degassing from Deccan volcanism in the latest Maastrichtian. The extent to which ocean pH (and atmospheric CO2 concentrations) changed in response to these contrasting acidification pressures, and the timescales of their recovery, may provide unique insight into the efficiency of the Earth's oceans in buffering greenhouse gas increases (through carbonate dissolution, weathering-derived alkalinity flux, and biological carbon cycling). The boron isotope palaeo-pH proxy in planktic foraminifera is well suited to such investigations, but its application over this interval has been problematic, not least due to a scarcity of sample material and a near-complete turnover of planktonic foraminiferal species across the K-Pg boundary. To attempt to circumvent these issues, we investigate the biological influences on boron isotope signals in Maastrichtian and Danian planktonic foraminifera, with the goal of producing more accurate palaeo-pH reconstructions. With these findings in mind, we present preliminary constraints on ocean pH and carbonate system dynamics across this critical interval of geological time.

  18. ICP-MS with hexapole collision cell for isotope ratio measurements of Ca, Fe, and Se.

    PubMed

    Boulyga, S F; Becker, J S

    2001-07-01

    To avoid mass interferences on analyte ions caused by argon ions and argon molecular ions via reactions with collision gases, an rf hexapole filled with helium and hydrogen has been used in inductively coupled plasma mass spectrometry (ICP-MS), and its performance has been studied. Up to tenfold improvement in sensitivity was observed for heavy elements (m > 100 u), because of better ion transmission through the hexapole ion guide. A reduction of argon ions Ar+ and the molecular ions of argon ArX+ (X = O, Ar) by up to three orders of magnitude was achieved in a hexapole collision cell of an ICP-MS ("Platform ICP", Micromass, Manchester, UK) as a result of gas-phase reactions with hydrogen when the hexapole bias (HB) was set to 0 V; at an HB of 1.6 V argon, and argon-based ions of masses 40 u, 56 u, and 80 u, were reduced by approximately four, two, and five orders of magnitude, respectively. The signal-to-noise ratio 80Se/ 40Ar2+ was improved by more than five orders of magnitude under optimized experimental conditions. Dependence of mass discrimination on collision-cell properties was studied in the mass range 10 u (boron) to 238 u (uranium). Isotopic analysis of the elements affected by mass-spectrometric interference, Ca, Fe, and Se, was performed using a Meinhard nebulizer and an ultrasonic nebulizer (USN). The measured isotope ratios were comparable with tabulated values from IUPAC. Precision of 0.26%, 0.19%, and 0.12%, respectively, and accuracy of 0.13% 0.25%, and 0.92%, respectively, was achieved for isotope ratios 44Ca/ 40Ca and 56Fe/57Fe in 10 microg L(-1) solution nebulized by means of a USN and for 78Se/80Se in 100 microg L(-1) solution nebulized by means of a Meinhard nebulizer.

  19. 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.

  20. Extending the Boundaries of Isotope Ratio MS - Latest Technological Improvements

    NASA Astrophysics Data System (ADS)

    Hilkert, A.

    2016-12-01

    Isotope ratio mass spectrometry has a long history, which started with the analysis of the isotopes of CO2. Over several decades a broad range of IRMS techniques has been derived like multi-collector high resolution ICP-MS, TIMS, noble gas static MS and gas IRMS. These different flavors of IRMS are now building a technology tool box, which allows to derive new applications build on new capabilities by combination of specific features of these sister technologies. In the 90's inductive coupled plasma ionization was added for the high precision analysis of rare elements. In 2000 extended multicollection opened the way into clumped isotopes. In 2008 the concept of a high resolution gas source IRMS was layed out to revolutionize stable gas IRMS recently followed by the combination of this static multicollection mode with fast mass scans of the single collector double focusing high resolution GCMS. Recently new technologies were created, like the mid infrared analyzers (IRIS) based on difference frequency generation lasers, the combination of a collision cell with HR MC ICPMS as well as the use of a high resolution electrostatic ion trap for extended stable isotope analysis on individual compounds. All these building blocks for IRMS address selected requirements of sample preparation, sample introduction, referencing, ionization, mass separation, ion detection or signal amplification. Along these lines new technological improvements and applications will be shown and discussed.

  1. Boron and boron isotope systematics in the peralkaline Ilímaussaq intrusion (South Greenland) and its granitic country rocks: A record of magmatic and hydrothermal processes

    NASA Astrophysics Data System (ADS)

    Kaliwoda, Melanie; Marschall, Horst R.; Marks, Michael A. W.; Ludwig, Thomas; Altherr, Rainer; Markl, Gregor

    2011-07-01

    Concentrations of boron in whole rocks and minerals of the peralkaline, 1.16 Ga Ilímaussaq intrusion and its granitic country rocks (South Greenland) were analysed using secondary ion mass spectrometry (SIMS) and prompt gamma neutron activation (PGNAA) analysis. The intrusion consists of an early augite-syenite shell, a later alkali-granite sheet and still later nepheline syenites, which dominate the Complex. Boron concentrations are high (250-280 μg/g) in all rocks containing fresh sodalite, whereas boron is constantly low in the sodalite-free augite syenites (4-6 μg/g) and in the alkali granites (7-22 μg/g). Rocks with sodalite altered to analcime contain only low amounts of boron (2-7 μg/g), which records boron extraction by late-magmatic fluids. Concentration profiles of B in the analysed minerals (olivine, amphibole, clinopyroxene, aenigmatite, eudialyte, biotite, feldspar, nepheline and sodalite) record magmatic fractionation to various extents, late-magmatic to hydrothermal fluid/rock interaction, and sub-solidus diffusion. Whole-rock concentration data cannot be directly translated into the geochemical evolution of the peralkaline melts, since they are largely affected by cumulate fractionation of sodalite and amphibole and furthermore by late-stage hydrothermal alteration processes resulting in B loss. However, trace-element concentrations of mineral zones representing equilibrium fractionation from magmatic liquids can be used in combination with mineral-melt partition coefficients to unravel the enrichment processes of elements in the melt. Boron isotope values of minerals from the intrusion and the country rocks resemble the trend observed for Li isotopes in an earlier study. Amphibole and feldspar display a clear trend from light boron in the inner nepheline syenitic part of the intrusion (δ11B = -20‰ and -17‰ for amphibole and feldspar, respectively) through intermediate values in the outer augite syenites (δ11B = -10‰ and -6‰ for

  2. Environmental controls on the boron and strontium isotopic composition of aragonite shell material of cultured Arctica islandica

    NASA Astrophysics Data System (ADS)

    Liu, Y.-W.; Aciego, S. M.; Wanamaker, A. D., Jr.

    2015-02-01

    Ocean acidification, the decrease in ocean pH associated with increasing atmospheric CO2, is likely to impact marine organisms, particularly those that produce carbonate skeletons or shells. Therefore it is important to investigate how environmental factors (seawater pH, temperature and salinity) influence the chemical compositions in biogenic carbonates. In this study we report the first high-resolution strontium (87Sr / 86Sr and δ88 / 86Sr) and boron (δ11B) isotopic values in the aragonite shell of cultured Arctica islandica (A. islandica). The 87Sr / 86Sr ratios from both tank water and shell samples show ratios nearly identical to the open ocean, which suggests that the shell material reflects ambient ocean chemistry without terrestrial influence. The 84Sr-87Sr double spike resolved shell δ 88 / 86Sr and Sr concentration data show no resolvable change throughout the culture period and reflect no theoretical kinetic mass fractionation throughout the experiment despite a temperature change of more than 15 °C. The δ11B records from the experiment show at least a 5‰ increase through the culture season (January 2010-August 2010), with low values from beginning to week 19 and higher values hereafter. The larger range in δ11B in this experiment compared to predictions based on other carbonate organisms (2-3‰) suggests that a species-specific fractionation factor may be required. A relatively strong correlation between the Δ pH (pHshell-pHsw) and seawater pH (pHsw) was observed (R2 = 0.34), which suggests that A. islandica partly regulates the pH of the extrapallial fluid. However, this proposed mechanism only explains approximately 34% of the variance in the δ11B data. Instead, a rapid rise in δ11B after week 19 suggests that the boron uptake of the shell changes when a temperature threshold of 13 °C is reached.

  3. Boron isotope systematics of tourmaline formation in the Sullivan Pb-Zn-Ag deposit, British Columbia, Canada

    USGS Publications Warehouse

    Jiang, S.-Y.; Palmer, M.R.; Slack, J.F.; Shaw, D.R.

    1999-01-01

    We report here the results of 54 boron isotope analyses of tourmaline associated with the giant Sullivan Pb-Zn-Ag deposit in southeastern British Columbia, Canada. The ??11B values range from -11.1 to -2.9???, which is almost as great as the range found worldwide in tourmalines from 33 massive sulfide deposits and tourmalinites in dominantly clastic metasedimentary terranes. The major control on the overall ??11B values of the Sullivan tourmalinites is the boron source. Potential controls over the large range of the data also include: (1) differences in formation temperatures of the tourmalinites, (2) different stages of tourmaline formation, (3) variations in the proportions of dissolved boron incorporated into the tourmaline (Rayleigh fractionation), (4) seawater entrainment, and (5) post-depositional metamorphism. The boron isotope data at Sullivan are consistent with boron derivation from leaching of footwall clastic sediments. However, the great abundance of tourmaline in the Sullivan deposit suggests that the local clastic sediments were not the sole source of boron, and we argue that non-marine evaporites, buried deep below the orebody, are the most viable source of this additional boron. It is likely that some of the variation in tourmaline ??11B values reflect mixing of boron from these two sources. Comparison of the potential effects of these controls with geologic and other geochemical evidence suggests that major causes for the wide range of ??11B values measured at Sullivan are seawater entrainment and Rayleigh fractionation, although in places, post-depositional alteration and thermal metamorphism were important in determining ??11B values of some of the recrystallized tourmalinites.

  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. 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.

  6. Isotope Flows and Flux Ratios in Biological Membranes

    PubMed Central

    Kedem, Ora; Essig, Alvin

    1965-01-01

    Precise evaluation of permeability of biological tissues is often prevented by imprecise knowledge of operative forces. This problem has been approached by analysis of fluxes of isotopic species applied to opposite surfaces of a membrane. A simple and rather general flux ratio equation has been derived which may permit evaluation of membrane permeability, even without knowledge of forces, or of the nature of active transport processes. Permeability as thus defined should be insensitive to coupled flows, either of other species or of metabolism. In appropriate circumstances application of the equation may permit evaluation of the contributions of the various processes to the transport of the examined species. Composite series membranes would be expected to obey the unmodified general equation. Heterogeneous parallel pathways would alter the relation in a predictable manner. The effect of isotope interaction is specifically incorporated. The formulation is applied to consideration of energetics of active transport. PMID:5855508

  7. 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.

  8. 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.

  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. Quadrupole mass spectrometer for a mobile laboratory to measure isotope ratios

    SciTech Connect

    Walton, J.R.; Smith, D.H.; McKown, H.S.; Carter, J.A.

    1981-01-01

    A mobile laboratory has been assembled for on-site inspection of plant operations handlng special nuclear materials. The isotopic composition of U, Pu, and other elements can be analyzed using a quadrupole mass spectrometer. Some results of analysis of uranium and boron standards are given. (DLC)

  11. 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.

  12. Isotopic Ratios in Nitrile Species on Titan using ALMA

    NASA Astrophysics Data System (ADS)

    Molter, Edward; Nixon, Conor; Cordiner, Martin; Serigano, Joseph; Irwin, Patrick; Teanby, Nicholas; Charnley, Steven; Lindeberg, Johan

    2016-06-01

    The atmosphere of Titan is primarily composed of molecular nitrogen (N2, ˜98%) and methane (CH4, ˜2%), but also hosts a myriad of trace organic species. Two of the simplest and most abundant of these are hydrogen cyanide (HCN) and cyanoacetylene (HC3N). The advent of ALMA provides the opportunity to observe rotational transitions in these molecules and their isotopologues with unprecendented sensitivity and spatial resolution. We searched through the ALMA archive for publicly available high-resolution observations of Titan as a flux calibrator source taken between April and July 2014; each integration lasted around 160 seconds. Using spectra of HCN and HC3N isotopologues found in these data, we derive vertical abundance profiles and determine the isotopic ratios 14N/15N and 12C/13C in these molecules. We also report the detection of a new HCN isotopologue on Titan, H13C6 15N, and use a high signal-to-noise spectrum of DCN to determine the D/H ratio in HCN on Titan for the first time. These isotopic ratios are leveraged to constrain the physical and chemical processes occurring in Titan's atmosphere.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Oxygen-18 Carbon Dioxide Isotope Ratio in Mars Atmosphere

    NASA Astrophysics Data System (ADS)

    Kostiuk, T.; Livengood, T. A.; Hewagama, T.; Smith, R.; Fast, K. E.; Annen, J.; Sonnabend, G.; Sornig, M.

    2012-09-01

    The determination of isotopic ratios on Mars is important to the study of atmospheric evolution [1]. The relative abundance of isotopes of CO2 provides insight into the loss of Mars' primordial atmosphere. Isotopic ratios also provide markers in the study of geochemistry of Mars meteorites and future returned samples formed in equilibrium with ambient atmosphere, and are probes of biogenic and abiotic chemistry, which differ in isotope fractionation. Due to its lesser gravity and relatively thin residual atmosphere, Mars' atmosphere should be enriched in heavy isotopes [1]. However Viking [2] results indicated an Earth-like singly substituted oxygen-18 CO2 isotopic ratio, 18OCO/OCO, with δ18O = 0±50‰ relative to Vienna Standard Mean Ocean Water (VSMOW). By comparison, isotopic ratios in Earth atmospheric CO2 are not uniquely defined due to seasonal and biotic variability, but have a range 0-41‰ relative to VSMOW [3, 4]. Phoenix lander TEGA [3] measurements found a modest enrichment of δ18O = 31.0±5.7‰. Only the Viking and Phoenix landers have carried a mass spectrometer to Mars, so far, until the arrival of Mars Science Laboratory in August 2012. Using ground-based spectroscopic techniques Krasnopolsky et al. [5] also found modest enrichment δ18O = 18±18‰. We present results from fully resolved spectroscopic measurements near 10.6 μm of both the normal and singly substituted oxygen- 18 CO2 lines, taken with the Goddard Space Flight Center Heterodyne Instrument for Planetary Winds And Composition (HIPWAC) at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii. Measurements with spectral resolving power λ/Δλ=107 were obtained in October 2007 with an instantaneous field-of-view on the planet of ~1 arcsec, at the locations shown in Fig. 1 as open squares. The solid and broken line tracks show Mars SPICAM measurements of ozone corresponding to ozone measurements also obtained with HIPWAC and shown as hatched and solid regions [6]. Figure 1

  18. Constraining the CO_{2} system of the early Cenozoic Greenhouse with boron isotopes

    NASA Astrophysics Data System (ADS)

    Kaminski, Matthew A.; Rae, James W. B.; Sexton, Philip F.; Anagnostou, Eleni; Foster, Gavin L.; Greene, Sarah; Greenop, Rosanna; Kirtland-Turner, Sandra; Ridgwell, Andy

    2017-04-01

    The CO2 dynamics of the early Cenozoic Greenhouse remain poorly understood: estimates of past atmospheric CO2 concentrations over this time are high but variable, and discussion remains on the driving mechanisms of long term changes in carbon cycling. This climatic state also provides the backdrop for numerous hyperthermal events, including the PETM, which may provide crucial insights to the current carbon cycle perturbation. This research aims to shed light on the state of the ocean carbonate system in the Paleocene and Early Eocene. We present new boron isotope data from benthic foraminifera, which can be used to reconstruct relative changes in ocean pH. These are coupled with modelling experiments performed with cGenie Earth system model runs to give new constraints on the carbon cycle and carbonate system of the early Cenozoic.

  19. 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

  20. 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

  1. 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.

  2. Carbon and nitrogen isotope ratios of juvenile winter flounder ...

    EPA Pesticide Factsheets

    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 (Ninigret Pond, Green Hill Pond and Point Judith Pond), an estuarine river (Narrow River) and Narragansett Bay. Results from sampling over a three-year period showed some year-to-year variability for 13C within waterbodies; however, 15N values were not significantly different (P > 0.05) within systems among the three years studied. he 13C trends observed along transects in Narrow River and Narragansett Bay showed isotopically depleted terrestrial signals in the upper reaches of the estuaries and more positive values indicative of marine organic material in the lower regions of these systems. Significant differences (P < 0.05) in 15N were observed among estuarine systems. Fish from the coastal lagoons had the lowest 15N values followed by those from Narrow River and then Narragansett Bay. Some unexpected trends in 15N were observed within Narragansett Bay. The Bay has a strong north-south gradient in nutrient concentrations due to large sewage inputs in the upper Bay which was not reflected in flounder 15N values. As expected, YOY flounder from stations in the lower-Bay had depleted 15N values compared to those from the other locations. However, the 15N ratios o

  3. 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.

  4. 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

  5. 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

  6. Measurement of isotope ratio of Ca{sup +} ions in a linear Paul Trap

    SciTech Connect

    Hashimoto, Y.; Minamino, K.; Nagamoto, D.; Hasegawa, S.

    2009-03-17

    Measurement of isotope ratios of Calcium is very useful in many fields. So we demonstrated the measurement of isotope ratios of {sup 40}Ca{sup +}(abundance 96.4%) to {sup 44}Ca{sup +}(2.09%) ions in a linear Paul trap with several laser lights tuning to the isotope shifts. And we found that the experimental parameters had large influences on the measurement of the isotope ratios.

  7. Boron Isotope Evidence for Shallow Fluid Transfer Across Subduction Zones by Serpentinized Mantle

    NASA Astrophysics Data System (ADS)

    Scambelluri, M.; Tonarini, S.; Agostini, S.; Cannaò, E.

    2012-12-01

    Boron Isotope Evidence for Shallow Fluid Transfer Across Subduction Zones by Serpentinized Mantle M. Scambelluri (1), S. Tonarini (2), S. Agostini (2), E. Cannaò (1) (1) Dipartimento di Scienze della Terra, Ambiente e vita, University of Genova, Italy (2) Istituto di Geoscienze e Georisorse-CNR, Pisa, Italy In subduction zones, fluid-mediated chemical exchange between slabs and mantle dictates volatile and incompatible element cycles and influences arc magmatism. Outstanding issues concern the sources of water for arc magmas and its slab-to-mantle wedge transport. Does it occur by slab dehydration beneath arc fronts, or by hydration of fore-arc mantle and subsequent subduction of the hydrated mantle? So far, the deep slab dehydration hypothesis had strong support, but the hydrated mantle wedge idea is advancing supported by studies of fluid-mobile elements in serpentinized wedge peridotites and their subducted high-pressure (HP) equivalents. Serpentinites are volatile and fluid-mobile element reservoirs for subduction: their dehydration causes large fluid and element flux to the mantle.However, direct evidence for their key role in arc magmatism and identification of dehydration environments has been elusive and boron isotopes can trace the process. Until recently, the altered oceanic crust (AOC) was considered the 11B reservoir for arcs, which largely display positive δ11B. However, shallow slab dehydration transfers 11B to the fore-arc mantle and leaves the residual AOC very depleted in 11B below arcs. Here we present high positive δ11B of HP serpentinized peridotites from Erro Tobbio (Ligurian Alps), recording subduction metamorphism from hydration at low-grade to eclogite-facies dehydration. We show a connection among serpentinite dehydration, release of 11B-rich fluids and arc magmatism. The dataset is completed by B isotope data on other HP Alpine serpentinites from Liguria and Lanzo Massif. In general, the δ11B of these rocks is heavy (16 to + 30 permil

  8. 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.

  9. Temporal variations in the influence of the subducting slab on Central Andean arc magmas: Evidence from boron isotope systematics

    NASA Astrophysics Data System (ADS)

    Jones, Rosemary E.; De Hoog, Jan C. M.; Kirstein, Linda A.; Kasemann, Simone A.; Hinton, Richard; Elliott, Tim; Litvak, Vanesa D.

    2014-12-01

    The Pampean flat-slab segment in the southern Central Andes represents an ideal setting at which to investigate how changes in the tectonic configuration of a subduction zone (convergence angles and rates, seamount subduction and shallowing slab angle) affects the recycling of subducted components to arc magmas. To constrain sources, particularly of slab-derived fluids and their contribution to arc magmatism, boron isotope and select major and trace element compositions were determined for pyroxene- and zircon-hosted melt inclusions obtained from a suite of Paleocene to Miocene arc magmatic rocks, from the southern Central Andes. Considerable changes in δ11B values and boron concentrations are observed with time. Significantly lower δ11B values (average = - 1.9 ± 2.2 ‰ (1 σ)) and B/Nb ratios (average = 3.3 ± 1.3 (1 σ)) were obtained for melt inclusions from Oligocene arc rocks (∼24 Ma) compared to those from the Paleocene (∼61 Ma) (averages = + 1.6 ± 0.8 ‰ and 17.8 ± 1.4 (1 σ), respectively) and the Miocene (∼18 Ma) (averages = + 4.7 ± 1.9 ‰ and 11.9 ± 5.5 (1σ), respectively). A slab-derived fluid with a δ11B composition of + 1.5 ‰, primarily derived from altered oceanic crust on the down-going slab, affected the source of the Paleocene arc magma. The source of the Oligocene arc magmas received less boron derived from the subducting slab (≲1% fluid addition) than the Paleocene and Miocene arc magmas (up to 3.5% fluid addition). This is consistent with a greater depth to the slab-mantle interface and is potentially related to the widening of the volcanic arc and more distal position of these samples relative to the trench during this time period. The higher δ11B values (up to ∼ 9 ‰) obtained for the Miocene melt inclusions record an increase in the influence of serpentinite-derived fluids on the source of arc magmas after ∼19.5 Ma. This is approximately coeval with the subduction of the Juan Fernandez Ridge (JFR), suggesting that

  10. Theoretical uncertainties in extracting cosmic-ray diffusion parameters: the boron-to-carbon ratio

    NASA Astrophysics Data System (ADS)

    Genolini, Yoann

    2016-05-01

    PAMELA and, more recently, AMS-02, are ushering us into a new era of greatly reduced statistical uncertainties in experimental measurements of cosmic ray fluxes. In particular, new determinations of traditional diagnostic tools such as the boron to carbon ratio (B/C) are expected to significantly reduce errors on cosmic-ray diffusion parameters, with important implications for astroparticle physics, ranging from inferring primary source spectra to indirect dark matter searches. It is timely to stress, however, that the conclusions inferred crucially depend on the framework in which the data are interpreted as well as on some nuclear input parameters. We aim at assessing the theoretical uncertainties affecting the outcome, with models as simple as possible while still retaining the key dependences. We compare different semi-analytical, two-zone model descriptions of cosmic ray transport in the Galaxy: infinite slab(lD), cylindrical symmetry (2D) with homogeneous sources, cylindrical symmetry (2D) with inhomogeneous source distribution. We tested for the effect of a primary source contamination in the boron flux by parametrically altering its flux. We also tested for nuclear cross-section uncertainties.

  11. 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

  12. Stable isotope methods: The effect of gut contents on isotopic ratios of zooplankton

    NASA Astrophysics Data System (ADS)

    Hill, J. M.; McQuaid, C. D.

    2011-05-01

    In the past decade there has been an increased awareness of the potential for methodological bias resulting from multiple pre-analytical procedures in foodweb interpretations based on stable isotope techniques. In the case of small organisms, this includes the effect of gut contents on whole body signatures. Although gut contents may not reflect actual assimilation, their carbon and nitrogen values will be isotopically lighter than after the same material has been assimilated. The potential skewing of isotopic ratios in whole organism samples is especially important for aquatic environments as many studies involve trophic relationships among small zooplankton. This is particularly important in pelagic waters, where herbivorous zooplankton comprise small taxa. Hence this study investigated the effect of gut contents on the δ13C and δ15N ratios of three size classes of zooplankton (1.0-2.0, 2.0-4.0 and >4.0 mm) collected using bongo net tows in the tropical waters of the south-west Indian Ocean. Animals were collected at night, when they were likely to be feeding, sieved into size classes and separated into genera. We focused on Euphausia spp which dominated zooplankton biomass. Three treatment types were processed: bulk animals, bulk animals without guts and tail muscle from each size class at 10 bongo stations. The δ15N ratios were influenced by zooplankton size class, presumably reflecting ontogenetic changes in diet. ANOVA post hoc results and correlations in δ15N signatures among treatments suggest that gut contents may not affect overall nitrogen signatures of Euphausia spp., but that δ13C signatures may be significantly altered by their presence. Carbon interpretations however, were complicated by potential effects of variation in chitin, lipids and metabolism among tissues and the possibility of opportunistic omnivory. Consequently we advocate gut evacuation before sacrifice in euphausiids if specific tissue dissection is impractical and recommend

  13. Determination of nitrogen-15 isotope fractionation in tropine: evaluation of extraction protocols for isotope ratio measurement by isotope ratio mass spectrometry.

    PubMed

    Molinié, Roland; Kwiecień, Renata A; Silvestre, Virginie; Robins, Richard J

    2009-12-01

    N-Demethylation of tropine is an important step in the degradation of this compound and related metabolites. With the purpose of understanding the reaction mechanism(s) involved, it is desirable to measure the 15N kinetic isotope effects (KIEs), which can be accessed through the 15N isotope shift (Deltadelta15N) during the reaction. To measure the isotope fractionation in 15N during tropine degradation necessitates the extraction of the residual substrate from dilute aqueous solution without introducing artefactual isotope fractionation. Three protocols have been compared for the extraction and measurement of the 15N/14N ratio of tropine from aqueous medium, involving liquid-liquid phase partitioning or silica-C18 solid-phase extraction. Quantification was by gas chromatography (GC) on the recovered organic phase and delta15N values were obtained by isotope ratio measurement mass spectrometry (irm-MS). Although all the protocols used can provide satisfactory data and both irm-EA-MS and irm-GC-MS can be used to obtain the delta15N values, the most convenient method is liquid-liquid extraction from a reduced aqueous volume combined with irm-GC-MS. The protocols are applied to the measurement of 15N isotope shifts during growth of a Pseudomonas strain that uses tropane alkaloids as sole source of carbon and nitrogen. The accuracy of the determination of the 15N/14N ratio is sufficient to be used for the determination of 15N-KIEs. Copyright 2009 John Wiley & Sons, Ltd.

  14. 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. © 2012 American Academy of Forensic Sciences.

  15. Sulfur isotopic ratio of DMS and DMSP from Lake Kinneret

    NASA Astrophysics Data System (ADS)

    Sela-Adler, Michal; Said-Ahmad, Ward; Eckert, Werner; Kamyshny, Alexey; Sivan, Orit; Amrani, Alon

    2014-05-01

    Volatile Organic sulfur compounds (VOSC) such as dimethylsulfide (DMS) are an important source of biogenic sulfur to the atmosphere. The main precursor of DMS is dimethylsulfoniopropionate (DMSP), a common osmolyte in marine algae. Atmospheric release of VOS compounds contributes to the formation of sulfate aerosols. The latter are of global importance due to their role as cloud-condensation nuclei. VOSC are abundant in terrestrial environments as well and may be involved in important biogeochemical cycles. In lake sediments, another mechanism for the formation of DMS by H2S methylation may be important. The 34S/32S ratio (d34S values) of DMSP of marine surface water around the globe is very homogeneous ranging between +18.9 o to +20.3 o and the fractionation between DMSP and DMS is < +1 o (Amrani et al. 2013). The δ34S values of DMS and other VOSC in sediments should be 34S depleted, similar to its H2S precursor (Oduro et al., 2011). Our goal was to quantify the benthic DMS and DMSP emissions from the sediments of warm monomictic Lake Kinneret relative to their formation by surface water algae by using sulfur isotope ratios. Water column samples and sediment samples from Lake Kinneret were purged and trap in order to extract the VOSC and then introduced to a GC/MC-ICPMS for isotopic measurements (Amrani et al. 2013). The δ34S of DMSP in the water and sediment columns of Lake Kinneret a mesotrophic monomictic lake were measured. Our preliminary results show δ34S values for DMSP ranged between +10.3 o and +13.4 o in the water column. The sulfate δ34S values ranged between +12.6 o to +14.9 o. δ34S -DMSP in the sediment column showed similar values between +9.4 o and +13.0 o, indicating a similar sulfur source. Similar δ34S values obtain for other VOSC such as ethanethiol that contributes significantly to the VOSC of Lake Kinneret sediments. Amrani, A., W. Said-Ahmad,Y. Shaked, and R. P. Kiene. 2013. Sulfur isotopes homogeneity of oceanic DMSP and DMS. PNAS 110

  16. 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.

  17. Boron isotopes in brachiopods during the end-Permian mass extinction: constraints on pH evolution and seawater chemistry

    NASA Astrophysics Data System (ADS)

    Jurikova, Hana; Gutjahr, Marcus; Liebetrau, Volker; Brand, Uwe; Posenato, Renato; Garbelli, Claudio; Angiolini, Lucia; Eisenhauer, Anton

    2017-04-01

    The global biogeochemical cycling of carbon is fundamental for life on Earth with the ocean playing a key role as the largest and dynamically evolving CO2 reservoir. The boron isotope composition (commonly expressed in δ11B) of marine calcium carbonate is considered to be one of the most reliable paleo-pH proxies, potentially enabling us to reconstruct past ocean pH changes and understand carbon cycle perturbations along Earth's geological record (e.g. Foster et al., 2008; Clarkson et al., 2015). Brachiopods present an advantageous and largely underutilised archive for Phanerozoic carbon cycle reconstructions considering their high abundance in the geological record and its origin dating back to the early Cambrian. Moreover, their shell made of low-magnesium calcite makes these marine calcifiers more resistant to post-depositional diagenetic alteration of primary chemical signals. We have investigated the δ11B using MC-ICP-MS (Neptune Plus) and B/Ca and other elemental ratios (Mg/Ca, Sr/Ca, Al/Ca, Li/Ca, Ba/Ca, Na/Ca and Fe/Ca) using ICP-MS-Quadrupole (Agilent 7500cx) from the same specimens in pristine brachiopod shells from two sections from northern Italy during the Late Permian. These sections cover the δ13C excursion in excess of ˜4 ‰ (Brand et al., 2012) and are associated with major climate and environmental perturbations that lead to the mass extinction event at the Permian-Triassic boundary. Particular emphasis will be placed on the implications of our new paleo-pH estimates on the seawater chemistry during the Late Permian. Brand, U., Posenato, R., Came, R., Affek, H., Angiolini, L., Azmy, K. and Farabegoli, E.: The end-Permian mass extinction: A rapid volcanic CO2 and CH4-climatic catastrophe, Chemical Geology 323, 121-144, doi:10.1016/j.chemgeo.2012.06.015, 2012. Clarkson, M.O., Kasemann, S.A., Wood, R.A., Lenton, T.M., Daines, S.J., Richoz, S., Ohnemueller, F., Meixner, A., Poulton, S.W. and Tipper, E.T.: Ocean acidification and the Permo

  18. Effectiveness of sulfur and boron isotopes in aerosols as tracers of emissions from coal burning in Asian continent

    NASA Astrophysics Data System (ADS)

    Sakata, Masahiro; Ishikawa, Tomomi; Mitsunobu, Satoshi

    2013-03-01

    The atmospheric concentrations and isotopic compositions of sulfur and boron were measured for aerosol samples (water soluble fraction) collected from April 2004 to March 2006 at two sites on the Japan Sea coast. SO42- originating from sea salts in the aerosols was negligible (only 1-2% of the total SO42-). The atmospheric concentrations of nonsea-salt SO42- (Snss) and total B (BT) were scattered widely, but the concentration ratio BT/Snss was relatively high during winter and relatively low during summer. Moreover, aerosols during winter were characterized by a high δ34S (δ34Snss) of nonsea-salt SO42- and a low δ11B (δ11BT) of total B, whereas aerosols during summer were characterized by a low δ34Snss and a high δ11BT. A negative correlation (r2 = 0.34, p < 0.001) was observed between δ34Snss and δ11BT in aerosols from the two sites, suggesting that those values are governed primarily by a mixing of two end-members. On the basis of air trajectory analysis, the first end-member is the air mass from "Northern China (>30°N)", whereas the second end-member is the air mass from "Japan and the Pacific Ocean". It is likely that SO42- and B in the air mass from northern China are strongly affected by coal burning, which satisfactorily reflects the characteristics of δ34S and δ11B (i.e., high δ34S and low δ11B) of coals formed in this region. Thus, both sulfur and boron isotopes in aerosols are effective as tracers of emissions from coal burning in northern China mainly during winter when the air mass from this region is dominant. On the other hand, the results of source identification suggested that the major sources of SO42- and B in the air mass from Japan and the Pacific Ocean are oil combustion in Japan and ocean sea salts, respectively.

  19. Boron contents and isotopic compositions of hog manure, selected fertilizers, and water in Minnesota

    USGS Publications Warehouse

    Komor, S.C.

    1997-01-01

    Boron-isotope (δ11B) values may be useful as surrogate tracers of contaminants and indicators of water mixing in agricultural settings. This paper characterizes the B contents and isotopic compositions of hog manure and selected fertilizers, and presents δ11B data for ground and surface water from two agricultural areas. Boron concentrations in dry hog manure averaged 61 mg/kg and in commercial fertilizers ranged from below detection limits in some brands of ammonium nitrate and urea to 382 mg/kg in magnesium sulfate. Values of δ11B of untreated hog manure ranged from 7.2 to 11.2o/oo and of N fertilizers were −2.0 to 0.7o/oo. In 22 groundwater samples from a sand-plain aquifer in east-central Minnesota, B concentrations averaged 0.04 mg/L and δ11B values ranged from 2.3 to 41.5o/oo. Groundwater beneath a hog feedlot and a cultivated field where hog manure was applied had B-isotope compositions consistent with the water containing hog-manure leachate. In a 775-km2 watershed with silty-loam soils in southcentral Minnesota: 18 samples of subsurface drainage from corn (Zea mays L.) and soybean (Glycine max L. Merr.) fields had average B concentrations of 0.06 mg/L and δ11B values of 5.3 to 15.1o/oo; 27 stream samples had average B concentrations of 0.05 mg/L and δ11B values of 1.0 to 19.0o/oo; and eight groundwater samples had average B concentrations of 0.09 mg/L and δ11B values of −0.3 to 23.0o/oo. Values of δ11B and B concentrations, when plotted against one another, define a curved mixing trend that suggests subsurface drainage and stream water contain mixtures of B from shallow and deep groundwater.

  20. 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

  1. 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.

  2. A new method for calibrating a boron isotope paleo-pH proxy using massive Porites corals

    NASA Astrophysics Data System (ADS)

    Kubota, Kaoru; Yokoyama, Yusuke; Ishikawa, Tsuyoshi; Suzuki, Atsushi

    2015-09-01

    The boron isotope ratio (δ11B) of marine biogenic carbonates can reconstruct pH and pCO2 of seawater, and potentially CO2 concentration in the atmosphere. To date, δ11B-pHSW calibration has been proposed via culturing experiments, where calcifying organisms are cultured under artificially acidified seawater. However, in scleractinian corals, reconstructed pH values using culture-based calibrations do not agree well with actual observations of seawater CO2 chemistry. Thus, another approach is needed to establish a more reliable calibration method. In this study, we established field-based calibrations for Chichijima and Tahiti, both located in subtropical gyres where surface seawater is close to CO2 equilibrium. We suggest a new approach to calibration of δ11B-pH in which the long-term δ11B variation of massive Porites corals is compared with the decreasing pH trend (i.e., ocean acidification) that has occurred since the Industrial Revolution. This calibration will offer a new avenue for studying seawater CO2 chemistry using coral δ11B in diverse settings, such as upwelling regions, coral reefs, and coastal areas.

  3. 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

  4. Variations in atmospheric concentrations and isotopic compositions of gaseous and particulate boron in Shizuoka City, Japan

    NASA Astrophysics Data System (ADS)

    Sakata, Masahiro; Phan, Hang Giang; Mitsunobu, Satoshi

    2017-01-01

    To clarify the partitioning and isotopic fractionation of boron (B) into the gas and particle phases in the atmosphere, the concentrations and isotopic compositions of gaseous and particulate B were measured concurrently for more than one year at a site in Shizuoka City, Japan. This area has few anthropogenic sources of B, such as coal combustion facilities. Gaseous B concentration showed clearly a seasonal variation, increasing during summer and decreasing during winter. Conversely, particulate B concentration tended to decrease during the warm season and increase during winter. The increase in gaseous B concentration during summer is attributable to the enhanced emissions of B from sea-salt degassing owing to higher temperatures and the predominance of winds from the Pacific Ocean. Moreover, the decrease in gaseous B concentration and the increase in particulate B concentration during winter is probably due to the enhanced condensation of gaseous B on atmospheric particles. The δ11B values of gaseous and particulate B varied largely, and did not indicate a distinctive seasonal variation. A positive correlation was observed between the δ11B values of gaseous and particulate B (R2 = 0.518, P < 0.001). Moreover, the δ11B values of particulate B were approximately 0-20‰ lower than those of gaseous B. There is an isotopic fractionation (ΔB(OH)4- -B(OH)3) of about -20‰ between B(OH)3 and B(OH)4- species in solution (Kakihana et al., 1977). This tends to support the hypotheses that gaseous B is transformed to particulate B through the reaction of condensed B(OH)3 with chemical constituents on particles to precipitate borates, and that the condensed B(OH)3 remaining on particles is unstable and evaporates.

  5. Water isotopic ratios from a continuously melted ice core sample

    NASA Astrophysics Data System (ADS)

    Gkinis, V.; Popp, T. J.; Blunier, T.; Bigler, M.; Schüpbach, S.; Kettner, E.; Johnsen, S. J.

    2011-11-01

    A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We built an interface between a Wavelength Scanned Cavity Ring Down Spectrometer (WS-CRDS) purchased from Picarro Inc. and a Continuous Flow Analysis (CFA) system. The system offers the possibility to perform simultaneuous water isotopic analysis of δ18O and δD on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub μl amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100% efficiency in a~home made oven at a temperature of 170 °C. A calibration procedure allows for proper reporting of the data on the VSMOW-SLAP scale. We apply the necessary corrections based on the assessed performance of the system regarding instrumental drifts and dependance on the water concentration in the optical cavity. The melt rates are monitored in order to assign a depth scale to the measured isotopic profiles. Application of spectral methods yields the combined uncertainty of the system at below 0.1‰ and 0.5‰ for δ18O and δD, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sample in the transfer lines limits the temporal resolution of the technique. In this work we investigate and assess these dispersion effects. By using an optimal filtering method we show how the measured profiles can be corrected for the smoothing effects resulting from the sample dispersion. Considering the significant advantages the technique offers, i.e. simultaneuous measurement of δ18O and δD, potentially in combination with chemical components that are traditionally measured on CFA systems, notable reduction on analysis time and power consumption, we consider it as an alternative to traditional isotope ratio mass spectrometry with the possibility to be deployed for field ice core studies. We present

  6. Water isotopic ratios from a continuously melted ice core sample

    NASA Astrophysics Data System (ADS)

    Gkinis, V.; Popp, T. J.; Blunier, T.; Bigler, M.; Schüpbach, S.; Johnsen, S. J.

    2011-06-01

    A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We build an interface between an Infra Red Cavity Ring Down Spectrometer (IR-CRDS) and a Continuous Flow Analysis (CFA) system. The system offers the possibility to perform simultaneuous water isotopic analysis of δ18O and δD on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub μl amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100 % efficiency in a home made oven at a temperature of 170 °C. A calibration procedure allows for proper reporting of the data on the VSMOW scale. We apply the necessary corrections based on the assessed performance of the system regarding instrumental drifts and dependance on humidity levels. The melt rates are monitored in order to assign a depth scale to the measured isotopic profiles. Application of spectral methods yields the combined uncertainty of the system at below 0.1 ‰ and 0.5 ‰ for δ18O and δD, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sample in the transfer lines limits the resolution of the technique. In this work we investigate and assess these dispersion effects. By using an optimal filtering method we show how the measured profiles can be corrected for the smoothing effects resulting from the sample dispersion. Considering the significant advantages the technique offers, i.e. simultaneuous measurement of δ18O and δD, potentially in combination with chemical components that are traditionally measured on CFA systems, notable reduction on analysis time and power consumption, we consider it as an alternative to traditional isotope ratio mass spectrometry with the possibility to be deployed for field ice core studies. We present data acquired in the framework of the NEEM deep ice core drilling project in

  7. 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.

  8. 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.

  9. A study of galactic cosmic ray propagation models based on the isotopic composition of the elements lithium, beryllium and boron

    NASA Technical Reports Server (NTRS)

    Hinshaw, G. F.; Wiedenbeck, M. E.; Greiner, D. E.

    1982-01-01

    A good test for a cosmic ray propagation model is its ability to predict the abundances of the light secondary nuclei lithium, beryllium, and boron. By using measured isotopic abundances of lithium, beryllium, and boron, Garcia-Munoz et al. (1979) were able to place limits on three important parameters of a leaky box propagation model. The considered parameters include the source spectral parameter, the leakage mean free path, and the characteristic adiabatic energy loss due to solar modulation. The present investigation is concerned with a critical evaluation of the information which can be deduced about these parameters from isotopic composition alone, taking into account the effects of uncertainties in the spallation cross section data.

  10. A study of galactic cosmic ray propagation models based on the isotopic composition of the elements lithium, beryllium and boron

    NASA Technical Reports Server (NTRS)

    Hinshaw, G. F.; Wiedenbeck, M. E.; Greiner, D. E.

    1982-01-01

    A good test for a cosmic ray propagation model is its ability to predict the abundances of the light secondary nuclei lithium, beryllium, and boron. By using measured isotopic abundances of lithium, beryllium, and boron, Garcia-Munoz et al. (1979) were able to place limits on three important parameters of a leaky box propagation model. The considered parameters include the source spectral parameter, the leakage mean free path, and the characteristic adiabatic energy loss due to solar modulation. The present investigation is concerned with a critical evaluation of the information which can be deduced about these parameters from isotopic composition alone, taking into account the effects of uncertainties in the spallation cross section data.

  11. Study of the boron levels in serum after implantation of different ratios nano-hexagonal boron nitride-hydroxy apatite in rat femurs.

    PubMed

    Atila, Alptug; Halici, Zekai; Cadirci, Elif; Karakus, Emre; Palabiyik, Saziye Sezin; Ay, Nuran; Bakan, Feray; Yilmaz, Sahin

    2016-01-01

    Boron and its derivatives are effective in bone recovery and osteointegration. However, increasing the boron levels in body liquids may cause toxicity. The aim of our study is to investigate serum boron levels using ICP-MS after implantation of different ratios of nano-hBN-HA composites in rat femurs. All rats were (n=126) divided into five experimental groups (n=24) and one healthy group (6 rats); healthy (Group1), femoral defect + %100 HA (Group2), femoral defect + %2.5 hBN + %97.5 HA (Group3), femoral defect + %5 hBN + %95 HA (Group4), femoral defect + %10 hBN + %90 HA (Group5), femoral defect + %100 hBN (Group6). The femoral defect was created in the distal femur (3mm drill-bit). Each implant group was divided into four different groups (n=24) also 6 rats sacrificed for each groups in one week intervals during four weeks. In our results; at 1, 2, 3, and 4 weeks after implantation near bone tissue, serum levels of boron were evaluated using ICP-MS. We demonstrated that neither short-term nor long-term implantation of hBN-HA composite resulted in statistically increased serum boron levels in experimental groups compared to healthy group. In conclusion, this study investigated the implant material produced form hBN-HA for the first time. Our data suggest that hBN is a new promising target for biomaterial and implant bioengineers. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Isotopic Composition of Boron Secondary Ions as a Function of Ion-Beam Fluence.

    NASA Astrophysics Data System (ADS)

    Baumel, Laurie Michelle

    The experiment performed in this work isolates and examines the effects of mass on the composition of the sputtered flux from a multi-component target. Chemical complexities are minimized by measuring sputtered ions from a target consisting only of two isotopes of one element. In this case, chemical effects as well as inter-atomic potentials are assumed to be identical for all constituents moving within the target, thus simplifying the target kinematics. Since any non-stoichiometry in the sputtered material should be caused only by the effects of mass on the kinetics in the target, measuring the sputtered material and comparing various analytical predictions with the experimental results leads to a better understanding of mass effects in these targets. 100-keV argon and neon were used to sputter an elemental target comprising the two naturally occurring isotopes of boron. The resulting secondary ions were examined with an electrostatic quadrupole mass analyzer. At low beam fluences (~1 times 20^{15} ions/cm ^2) a light-isotope secondary ion enhancement is observed relative to the steady-state secondary ion yields collected at higher beam fluences ( ~5 times 10 ^{17} ions/cm^2 ). The steady-state ion yields are representative of the bulk composition of the target. The enhancement (46.1perthous for Ne^+ irradiation and 51.8perthous for Ar^+ irradiation) is large compared to the predictions of analytical theories and is determined to be independent of variations in surface potential, chemical effects, and surface impurities. This effect is consistent with an explanation based on an energy and momentum asymmetry in the collision cascade. The asymmetry was caused by an extra collision mechanism which allowed light particles to backscatter 180^circ (towards the target surface) from underlying heavier target particles whereas the reverse process can not occur. When irradiated with projectiles heavier than the target constituents, the heavier target particles had a higher

  13. 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

  14. Processes for the "vital effect" of Porites corals as revealed by microanalysis of oxygen, carbon and boron isotopic compositions

    NASA Astrophysics Data System (ADS)

    Rollion-Bard, C.; Chaussidon, M.; France-Lanord, C.

    2003-04-01

    Since the discovery by Knutson et al. (1972) of annual banding in massive corals, they have intensively been used to provide paleoclimate reconstructions. The oxygen isotopic composition (18O) of coral aragonite skeletons is a function of sea surface temperature (SST) and salinity (SSS) through the 18O of the seawater in which the carbonate precipitates and pH of the calcifying fluid. Carbon cycle in hermatypic corals is relatively complex because of the interaction between symbiotic algae (zooxanthellae) and coral (Goreau, 19777). Coral 13C seems to be under influence of the ratio between algae photosynthesis and algae and coral respiration (Swart, 1983). The carbonate deposited by some foraminifera and scleractinian corals is depleted 13C and 18O relative to isotope equilibrium with ambient seawater. This deviation of the biogenic carbonate - water fractionation from the inorganic fractionation is called the "vital effect" (Urey et al., 1951). Different explanations for the vital effect are proposed: (1) McConnaughey (1989) attributes the coral disequilibria to kinetic effects. (2) Spero et al. (1997) and Zeebe (1999) consider that the carbonate depletion in 18O is due to [CO32-] or pH variations. The carbon isotopic disequilibrium would be due, in this case, to 13C depleted metabolic DIC incorporation coming from the respiration. The micrometer scale analysis by ion microprobe of B, C and O isotopic compositions can allow to better understand responsible process(es) of the vital effect and the existence of a great diversity in 18O - SST calibrations for differents colonies of the same species. These analyses show that 11B and 18O of coral skeleton have a great variability at micrometer scale (10 and 12 , respectively), whereas 13C have no so important variations and that all the values are in the range of 13C measured by "classical" method (acid digestion and mass spectrometry). Thus the in

  15. Boron and Strontium isotope systematics in deeply subducted alpine-serpentinites: evidence of high-11B fluid flow

    NASA Astrophysics Data System (ADS)

    Tonarini, Sonia; Scambelluri, Marco

    2010-05-01

    Boron and strontium isotope systematics are widely applied tracers to understand recycling processes during subduction. However, very few studies are addressed to the geochemical behaviour of these isotope ratios in high (HP) to ultrahigh-pressure (UHP) serpentinites that experienced pressure-temperature conditions similar to those of modern subduction zones. Here we present delta-11B and 87Sr/86Sr ratios of the Erro-Tobbio peridotite (Ligurian Alps) a slice of serpentinized mantle involved in subduction and high-pressure recrystallization during the Alpine orogeny. The analyzed sample set includes serpentinized peridotite samples recrystallized at increasing P-T conditions: from relatively low P-T (chrysotile and lizardite are the dominant serpentine minerals) to eclogite-facies conditions (antigorite + olivine + Ti clinohumite form the stable paragenesis). During subduction, ductile deformation under HP conditions was focused in serpentinite mylonite shear zones (high-strain domains) surrounding volumes of HP serpentinized peridotite unaffected by plastic deformation (low-strain domains). The latter diffusely preserve serpentinized mantle peridotites with low P-T overprint retaining pristine mantle textures and assemblages. In general, the delta-11B in these products is heavy, with the majority of samples exceeding delta-11B of 16 permil and reaching extreme values of + 24 permil. The 87Sr/86Sr ratios range between 0.7044 and 0.7065, significantly lower than the values of serpentinites formed during interaction with seawater-dominated fluids and close to the seawater 87Sr/86Sr. In more detail, the low P-T serpentinized peridotites are characterized by the wider range of delta-11B variability (+3.8 to +24 permil). The low-strain HP peridotites show a comparably wide range in delta-11B (+6.8 to +20 permil). More homogeneous and generally higher delta-11B were measured in HP mylonitic serpentinites (delta-11B between +16.7 and +24 permil): these rocks also display

  16. HIGHLY VARIABLE HELIUM ISOTOPE RATIOS IN THE VANUATU VOLCANIC ARC

    NASA Astrophysics Data System (ADS)

    Jean-Baptiste, P.; Allard, P.; Bani, P.; Garaebiti, E.; Pelletier, B.; Fourré, E.; Metrich, N.

    2009-12-01

    The Vanuatu (former New Hebrides) island arc results from the eastward subduction of the Australian plate beneath the North Fiji back-arc basin. Whereas its southern part is characterized by a single chain of volcanic islands parallel to a well-defined trench, the structure of its central part is strongly modified by the collision-subduction of the d’Entrecasteaux Zone, lacking a deep trench and consisting of three N-S chains of volcanic islands. In order to get further insight into the source of volcanism in this complex tectonic setting, we have analysed helium isotopes in groundwaters and hot springs (37°-90°C) from both the southern (Tanna and Efate) and central (Ambrym, Ambae and Pentecost) volcanic islands. Additional data were also acquired on bubbling gases and olivine phenocrysts from the islands of Ambrym and Ambae, respectively. Most waters show substantial helium enrichment (between 1.3 and 24.3 times the atmospheric solubility). 3He/4He ratios vary over a wide range, going from low (crustal He-influenced) 4.4 - 4.6 Ra and 4.8 -5.6 Ra in Efate and Pentecost respectively, to 6.3 - 7.0 Ra in Tanna, 6.8 - 8.2 Ra in Ambae, and up to 10.05 Ra in Ambrym (measured in both waters and bubbling gases). This latter value is similar to those measured in the nearby north Fiji basin (9-10 Ra - Ishibashi et al., EPSL, 1994) and approaches those, further north, of Manus basin glasses (12.2±1 Ra - Macpherson et al., Geology, 1998), suggesting a possible plume (or hotspot) influence. In Ambrym, this influence is confined to the north of the central rift zone - coincident with a major volcano-tectonic fault structure, since fluids in the southwest part of the island (a few kilometres apart) display typical arc-type ratios of 7 Ra. Interestingly, the analysis of tremor activity from the two large active cones located at the centre of the island, the Marum and Benbow volcanos, also suggest two distinct magmatic sources beneath Ambrym (Legrand et al., GRL 2005). Clearly

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Theoretical uncertainties in extracting cosmic-ray diffusion parameters: the boron-to-carbon ratio

    NASA Astrophysics Data System (ADS)

    Genolini, Y.; Putze, A.; Salati, P.; Serpico, P. D.

    2015-08-01

    Context. PAMELA and, more recently, AMS-02, are ushering us into a new era of greatly reduced statistical uncertainties in experimental measurements of cosmic-ray fluxes. In particular, new determinations of traditional diagnostic tools such as the boron-to-carbon ratio (B/C) are expected to significantly reduce errors on cosmic-ray diffusion parameters, with important implications for astroparticle physics, ranging from inferring primary source spectra to indirect dark matter searches. Aims: It is timely to stress, however, that the conclusions obtained crucially depend on the framework in which the data are interpreted as well as on some nuclear input parameters. We aim at assessing the theoretical uncertainties affecting the outcome, with models as simple as possible while still retaining the key dependencies. Methods: We compared different semi-analytical, two-zone model descriptions of cosmic-ray transport in the Galaxy: infinite slab(1D), cylindrical symmetry (2D) with homogeneous sources, cylindrical symmetry (2D) with inhomogeneous source distribution. We tested for the effect of a primary source contamination in the boron flux by parametrically altering its flux. We also tested for nuclear cross-section uncertainties. All hypotheses were compared by χ2 minimisation techniques to preliminary results from AMS-02. Results: We find that the main theoretical bias on the determination of the diffusion coefficient index δ (up to a factor two) is represented by the assumption that no injection of boron takes place at the source. The next most important uncertainty is represented by cross-section uncertainties, which reach ± 20% in δ. As a comparison, nuclear uncertainties are more important than the shift in the best-fit when introducing a convective wind of velocity ≲30 km s-1, with respect to a pure diffusive baseline model. Perhaps surprisingly, homogeneous 1D vs. 2D performances are similar in determining diffusion parameters. An inhomogeneous source

  3. 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.; hide

    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.

  4. 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

  5. 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.

  6. High Acidification Rate of Norwegian Sea Revealed by Boron Isotopes in the Deep-Sea Coral Madrepora Oculata

    NASA Astrophysics Data System (ADS)

    Gonzalez, C.; Douville, E.; Hall-Spencer, J.; Montagna, P.; Louvat, P.; Gaillardet, J.; Frank, N.; Bordier, L.; Juillet-Leclerc, A.

    2012-12-01

    Ocean acidification and global warming due to the increase of anthropogenic CO2 are major threats for marine calcifying organisms, such as deep-sea corals, particularly in high-latitude regions. In order to evaluate the current anthropogenic perturbation and to properly assess the impacts and responses of calcifiers to previous changes in pH it is critical to investigate past changes of the seawater carbonate system. Unfortunately, current instrumental records of oceanic pH are limited, covering only a few decades. Scleractinian coral skeletons record chemical parameters of the seawater in which they grow. However, pH variability over multidecadal timescales remains largely unknown in intermediate and deep seawater masses. Here we present a study that highlights the potential of deep-sea-corals to overcome the lack of long-term pH records and that emphasizes a rapid acidification of high latitude subsurface waters of Norwegian Sea during the past decades. We have reconstructed seawater pH and temperature from a well dated deep-sea coral specimen Madrepora oculata collected alive from Røst reef in Norwegian Sea (67°N, 9°E, 340 m depth). This large branching framework forming coral species grew its skeleton over more than four decades determined using AMS 14C and 210Pb dating (Sabatier et al. 2012). B-isotopes and Li/Mg ratios yield an acidification rate of about -0.0030±0.0008 pH-unit.year-1 and a warming of 0.3°C during the past four decades (1967-2007). Overall our reconstruction technique agrees well with previous pH calculations (Hönisch et al., 2007 vs. Trotter et al., 2011 and McCulloch et al., 2012, i.e. the iterative method), but additional corrections are here applied using stable isotope correlations (O, C, B) to properly address kinetic fractionation of boron isotopes used for pH reconstruction. The resulting pH curve strongly anti-correlates with the annual NAO index, which further strengthens our evidence for the ocean acidification rate

  7. Development and validation of a single collector ICPMS procedure to determine boron isotopeic compositions of water and food samples

    NASA Astrophysics Data System (ADS)

    Vogl, Jochen; Rosner, Martin; Pritzkow, Wolfgang

    2010-05-01

    Authenticity and provenance studies as well as issues in environmental- and geo-sciences are hot topics in nowadays isotope research. Elements being known for their natural isotopic variation, such as lead and strontium, are being used to assign the provenance of artefacts, food and other products. A recent study revealed the potential of boron (B) isotopes for delivering information on the provenance of crop plants. To offer alternative analytical instrumentations beside the classical TIMS procedures a single collector ICPMS procedure for B isotope analyses has been developed and validated. This procedure should enable more B isotope studies, as single collector ICPMS intruments are more widepread in the relevant laboratories compared to TIMS. The developed procedures for the determination of B isotopic compositions use a magnetic sector ICPMS and consist of one low resolution (LR) and one medium resolution (MR) procedure. The absolute standard deviation for the δ11B determination in three independently measured samples lies between 0.2 and 0.8 ‰ for the LR and between 0.3 and 1.5 ‰ for the MR. The expanded uncertainties with a coverage factor of k=2 range between 1.4 and 1.6 ‰ for the LR and between 2.9 and 3.2 ‰ for the MR. The trueness, expressed as average deviation from the reference values, is less than 1.1 ‰ for LR and 0.8 ‰ for MR. To test the practicability of the procedure the matrix tolerance has been investigated. Using a measurement solution containing 100 µg/kg boron a matrix of 2 mg/kg of alkaline and earth alkaline elements was found as a limit for stable instrumental mass discrimination. Thus a highly efficient matrix separation is required, similar to TIMS. The developed procedure is well suited for the for B isotope studies of various matrices and especially the LR procedure offers relatively small uncertainties combined with high sample throughput.

  8. Chemical and boron isotopic composition of tourmaline from the Mariinsky emerald deposit, Central Urals, Russia

    NASA Astrophysics Data System (ADS)

    Baksheev, Ivan A.; Trumbull, Robert B.; Popov, Mikhail P.; Erokhin, Yuri V.; Kudryavtseva, Olesya E.; Yapaskurt, Vasily O.; Khiller, Vera V.; Vovna, Galina M.; Kiselev, Vladimir I.

    2017-07-01

    Tourmaline is abundant at the Mariinsky schist-hosted emerald deposit in the Central Urals, Russia, both in emerald-bearing phlogopite veins (type 1) and later, emerald-free pockets, lenses, and veinlets cutting the phlogopite veins (type 2). The Ca content in tourmaline is influenced by the host rocks (ultramafic and mafic rocks), associated minerals, and minerals crystallized before tourmaline (amphibole, fluorite, margarite). The Na concentration in tourmaline depends on the presence or absence of paragonite, and the association with micas also strongly influences the contents of Li, Zn, Ni, and Co in tourmaline. Type 1 tourmalines associated with phlogopite are relatively depleted in these elements, whereas type 2 tourmalines associated with margarite or paragonite are enriched. Some differences in isomorphic substitutions along with the trace element composition (Zn, V, Sr, Co, REE) may have value in exploration of emerald-bearing and emerald-free veins in schist-hosted emerald deposits. The δ11B values in tourmaline of all types fall in a narrow total range from -11.3 to -8.4‰. These values, combined with a mineralization temperature of 420-360 °C, yield an estimated δ11B fluid composition of -7.4 to -6.8‰ suggesting a mixed source of boron, likely dominated from the granitic rocks surrounding the emerald belt. The narrow range of B-isotope compositions in tourmaline from throughout the Mariinsky deposit suggests a well-mixed hydrothermal system.

  9. Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures

    SciTech Connect

    Sharp, Ian D.; Bracht, Hartmut A.; Silvestri, Hughes H.; Nicols, Samuel P.; Beeman, Jeffrey W.; Hansen, John L.; Nylandsted Larsen, Arne; Haller, Eugene E.

    2002-04-01

    Isotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. {sup 30}Si was used as a tracer through a multilayer structure of alternating natural Si and enriched {sup 28}Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850 C and 1100 C. A specially designed ion- implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

  10. Boron isotopes in tourmaline from the ca. 3.7-3.8 Ga Isua supracrustal belt, Greenland: Sources for boron in Eoarchean continental crust and seawater

    NASA Astrophysics Data System (ADS)

    Grew, Edward S.; Dymek, Robert F.; De Hoog, Jan C. M.; Harley, Simon L.; Boak, Jeremy; Hazen, Robert M.; Yates, Martin G.

    2015-08-01

    Boron is highly concentrated in Earth's crust relative to primitive mantle. However, when present-day crustal concentrations were achieved remains debatable. It has been proposed that seawater boron δ11B was lower than at present, consistent with a model relating increase in sea-water δ11B to the proportion of B extracted from Earth's mantle into the oceans and crust. Our in situ ion microprobe analyses of tourmaline in 17 samples from the Eoarchean Isua supracrustal belt, Southwest Greenland, gave the following average δ11B with uncertainties ranging from ±0.4 to ±1.9‰: δ11B = -7.1 to -11.5‰ in amphibolite; δ11B = -10.5 to -25.3‰ in mica schist; δ11B = -19.2‰ in metachert (one sample), and δ11B = -21.9‰ in metaconglomerate (one sample). Tourmaline is largely schorl-dravite, rarely uvite-feruvite, and shows color and compositional zoning. δ11B varies from grain to grain in most samples; grains in a kyanite-staurolite schist are isotopically zoned, possibly because the rims incorporated B released by muscovite breakdown. The patterns in color-zoned tourmaline grains in our samples are not consistent with detrital origin of the cores, which rules out the possibility of there being tourmaline detritus from pre-existing continental crust in the studied samples. The tourmaline-bearing rocks are found in both the ca. 3700 Ma northern and ca. 3800 Ma southern terranes in the Isua supracrustal belt. Following an approach suggested by Chaussidon and Appel, we estimated Eoarchean seawater δ11B by calculating back from δ11B of tourmaline in metasedimentary rocks using fractionation of boron isotopes between clays and muscovite, tourmaline and aqueous fluid. This calculation gave an estimated δ11B ≈ +14 ± 15‰ for Eoarchean seawater, 25‰ lower than present-day seawater (δ11B = +39.5‰). For comparison, an estimate obtained simply by direct comparison of δ11B for Eoarchean and Phanerozoic tourmaline presumed to have crystallized in similar

  11. Compilation of minimum and maximum isotope ratios of selected elements in naturally occurring terrestrial materials and reagents

    USGS Publications Warehouse

    Coplen, T.B.; Hopple, J.A.; Böhlke, J.K.; Peiser, H.S.; Rieder, S.E.; Krouse, H.R.; Rosman, K.J.R.; Ding, T.; Vocke, R.D.; Revesz, K.M.; Lamberty, A.; Taylor, P.; De Bievre, P.

    2002-01-01

    Documented variations in the isotopic compositions of some chemical elements are responsible for expanded uncertainties in the standard atomic weights published by the Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry. This report summarizes reported variations in the isotopic compositions of 20 elements that are due to physical and chemical fractionation processes (not due to radioactive decay) and their effects on the standard atomic weight uncertainties. For 11 of those elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine, copper, and selenium), standard atomic weight uncertainties have been assigned values that are substantially larger than analytical uncertainties because of common isotope abundance variations in materials of natural terrestrial origin. For 2 elements (chromium and thallium), recently reported isotope abundance variations potentially are large enough to result in future expansion of their atomic weight uncertainties. For 7 elements (magnesium, calcium, iron, zinc, molybdenum, palladium, and tellurium), documented isotope-abundance variations in materials of natural terrestrial origin are too small to have a significant effect on their standard atomic weight uncertainties. This compilation indicates the extent to which the atomic weight of an element in a given material may differ from the standard atomic weight of the element. For most elements given above, data are graphically illustrated by a diagram in which the materials are specified in the ordinate and the compositional ranges are plotted along the abscissa in scales of (1) atomic weight, (2) mole fraction of a selected isotope, and (3) delta value of a selected isotope ratio. There are no internationally distributed isotopic reference materials for the elements zinc, selenium, molybdenum, palladium, and tellurium. Preparation of such materials will help to make isotope ratio measurements among

  12. 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.

  13. 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.

  14. LITHIUM-BERYLLIUM-BORON ISOTOPIC COMPOSITIONS IN METEORITIC HIBONITE: IMPLICATIONS FOR ORIGIN OF {sup 10}Be AND EARLY SOLAR SYSTEM IRRADIATION

    SciTech Connect

    Liu, Ming-Chang; Nittler, Larry R.; Alexander, Conel M. O'D.; Lee, Typhoon

    2010-08-10

    NanoSIMS isotopic measurements of Li, Be, and B in individual hibonite grains extracted from the Murchison meteorite revealed that {sup 10}B excesses correlate with the {sup 9}Be/{sup 11}B ratios in {sup 26}Al-free PLAty hibonite Crystals. From these data, an initial {sup 10}Be/{sup 9}Be = (5.5 {+-} 1.6) x 10{sup -4} (2{sigma}) and {sup 10}B/{sup 11}B = 0.2508 {+-} 0.0015 can be inferred. On the other hand, chondritic boron isotopic compositions were found in {sup 26}Al-bearing Spinel-HIBonite spherules, most likely due to contamination with normal boron. No {sup 7}Li excesses due to {sup 7}Be decay were observed. When combined with previously reported data, the new data yield the best defined {sup 10}Be/{sup 9}Be = (5.3 {+-} 1.0) x 10{sup -4} (2{sigma}) and {sup 10}B/{sup 11}B = 0.2513 {+-} 0.0012 for PLACs. A comparison of this value and the best constrained {sup 10}Be/{sup 9}Be = (8.8 {+-} 0.6) x 10{sup -4} in CV Ca-Al-rich inclusions supports a heterogeneous distribution of {sup 10}Be and its protosolar irradiation origin. We consider two possible irradiation scenarios that could potentially lead to the observed Li-Be-B isotopic compositions in PLACs. Although in situ irradiation of solids with hibonite chemistry seems to provide the simplest explanation, more high quality data will be needed for quantitatively constraining the irradiation history.

  15. 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.

  16. How strange was the Strangelove Ocean? New insights from Boron Isotopes.

    NASA Astrophysics Data System (ADS)

    Henehan, M. J.; Ridgwell, A.; Thomas, E.; Zhang, S.; Planavsky, N.; Alegret, L.; Schmidt, D. N.; Rae, J. W. B.; Foster, G. L.; Huber, B. T.; Hull, P. M.

    2016-12-01

    The idea of the `Strangelove Ocean'1 has captured the imagination of palaeoceanographers (and the public) since it was posited to explain the collapse or reverse in surface-deep ocean δ13C gradients after the Cretaceous-Palaeogene (K-Pg) boundary1. It describes a post-extinction ocean where primary productivity was drastically reduced, eliminating the surface-to-deep carbon isotope gradient produced by the biological pump. Survival of benthic foraminifera across the K-Pg (suggesting a persistent supply of organic matter to the deep) is difficult to reconcile with this ideae.g. 2. Geochemical proxies also suggest that severe export productivity reductions were at most regional3. This mismatch between patterns in δ13C and other indicators has thus been interpreted as a signal of changing vital effects in post-extinction pelagic calcifiers, toward lighter δ13C e.g. 2. However, it may be that vital effects in earliest Palaeocene foraminiferal survivors can account for only part of the convergence in δ13C between surface and deep ocean.4 In addition, analysis of carbonate preservation after the K-Pg boundary indicates large-scale carbonate system/ocean pH shifts at this time5, which could have produced secular changes in carbon isotope signals. Here we present new paired benthic and planktic boron isotope measurements that allow us to examine surface to deep ocean pH gradients (which in today's ocean are driven largely by biological activity) across the K-Pg boundary interval and into the early Palaeocene. We then couple these to model simulations to untangle the carbon cycle drivers, both physical and biological, that could have caused these changes in ocean pH gradients. We discuss implications for our understanding of this important interval in Earth history, with reference to the mechanisms of Earth system recovery following mass extinction. References:1. Hsü, K. J. & McKenzie, J. A., 1985. AGU Geophysical Monograph Series 32. doi:10.1029/GM032p0487 2. Alegret

  17. A sorghum (Sorghum bicolor) mutant with altered carbon isotope ratio.

    PubMed

    Rizal, Govinda; Karki, Shanta; Thakur, Vivek; Wanchana, Samart; Alonso-Cantabrana, Hugo; Dionora, Jacque; Sheehy, John E; Furbank, Robert; von Caemmerer, Susanne; Quick, William Paul

    2017-01-01

    Recent efforts to engineer C4 photosynthetic traits into C3 plants such as rice demand an understanding of the genetic elements that enable C4 plants to outperform C3 plants. As a part of the C4 Rice Consortium's efforts to identify genes needed to support C4 photosynthesis, EMS mutagenized sorghum populations were generated and screened to identify genes that cause a loss of C4 function. Stable carbon isotope ratio (δ13C) of leaf dry matter has been used to distinguishspecies with C3 and C4 photosynthetic pathways. Here, we report the identification of a sorghum (Sorghum bicolor) mutant with a low δ13C characteristic. A mutant (named Mut33) with a pale phenotype and stunted growth was identified from an EMS treated sorghum M2 population. The stable carbon isotope analysis of the mutants showed a decrease of 13C uptake capacity. The noise of random mutation was reduced by crossing the mutant and its wildtype (WT). The back-cross (BC1F1) progenies were like the WT parent in terms of 13C values and plant phenotypes. All the BC1F2 plants with low δ13C died before they produced their 6th leaf. Gas exchange measurements of the low δ13C sorghum mutants showed a higher CO2 compensation point (25.24 μmol CO2.mol-1air) and the maximum rate of photosynthesis was less than 5μmol.m-2.s-1. To identify the genetic determinant of this trait, four DNA pools were isolated; two each from normal and low δ13C BC1F2 mutant plants. These were sequenced using an Illumina platform. Comparison of allele frequency of the single nucleotide polymorphisms (SNPs) between the pools with contrasting phenotype showed that a locus in Chromosome 10 between 57,941,104 and 59,985,708 bps had an allele frequency of 1. There were 211 mutations and 37 genes in the locus, out of which mutations in 9 genes showed non-synonymous changes. This finding is expected to contribute to future research on the identification of the causal factor differentiating C4 from C3 species that can be used in the

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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‰.

  3. 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...

  4. 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.

  5. 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...

  6. 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.

  7. Calibration strategies for the determination of stable carbon absolute isotope ratios in a glycine candidate reference material by elemental analyser-isotope ratio mass spectrometry.

    PubMed

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

    2015-04-01

    We report a methodology for the determination of the stable carbon absolute isotope ratio of a glycine candidate reference material with natural carbon isotopic composition using EA-IRMS. For the first time, stable carbon absolute isotope ratios have been reported using continuous flow rather than dual inlet isotope ratio mass spectrometry. Also for the first time, a calibration strategy based on the use of synthetic mixtures gravimetrically prepared from well characterised, highly (13)C-enriched and (13)C-depleted glycines was developed for EA-IRMS calibration and generation of absolute carbon isotope ratio values traceable to the SI through calibration standards of known purity. A second calibration strategy based on converting the more typically determined delta values on the Vienna PeeDee Belemnite (VPDB) scale using literature values for the absolute carbon isotope ratio of VPDB itself was used for comparison. Both calibration approaches provided results consistent with those previously reported for the same natural glycine using MC-ICP-MS; absolute carbon ratios of 10,649 × 10(-6) with an expanded uncertainty (k = 2) of 24 × 10(-6) and 10,646 × 10(-6) with an expanded uncertainty (k = 2) of 88 × 10(-6) were obtained, respectively. The absolute carbon isotope ratio of the VPDB standard was found to be 11,115 × 10(-6) with an expanded uncertainty (k = 2) of 27 × 10(-6), which is in excellent agreement with previously published values.

  8. Stable Isotope Ratios as a Biomarker on Mars

    NASA Astrophysics Data System (ADS)

    van Zuilen, Mark

    2008-03-01

    As both Earth and Mars have had similar environmental conditions at least for some extended time early in their history (Jakosky and Phillips in Nature 412:237-244, 2001), the intriguing question arises whether life originated and evolved on Mars as it did on Earth (McKay and Stoker in Rev. Geophys. 27:189-214, 1989). Conceivably, early autotrophic life on Mars, like early life on Earth, used irreversible enzymatically enhanced metabolic processes that would have fractionated stable isotopes of the elements C, N, S, and Fe. Several important assumptions are made when such isotope fractionations are used as a biomarker. The purpose of this article is two-fold: (1) to discuss these assumptions for the case of carbon and to summarize new insights in abiologic reactions, and (2) to discuss the use of other stable isotope systems as a potential biomarker. It is concluded that isotopic biomarker studies on Mars will encounter several important obstacles. In the case of carbon isotopes, the most important obstacle is the absence of a contemporary abiologic carbon reservoir (such as carbonate deposits on Earth) to act as isotopic standard. The presence of a contemporary abiologic sulfate reservoir (evaporite deposits) suggests that sulfur isotopes can be used as a potential biomarker for sulfate-reducing bacteria. The best approach for tracing ancient life on Mars will be to combine several biomarker approaches; to search for complexity, and to combine small-scale isotopic variations with chemical, mineralogical, and morphological observations. An example of such a study can be a layer-specific correlation between δ 13C and δ 34S within an ancient Martian evaporite, which morphologically resembles the typical setting of a shallow marine microbial mat.

  9. Stable Isotope Ratios as a Biomarker on Mars

    NASA Astrophysics Data System (ADS)

    van Zuilen, Mark

    As both Earth and Mars have had similar environmental conditions at least for some extended time early in their history (Jakosky and Phillips in Nature 412:237-244, 2001), the intriguing question arises whether life originated and evolved on Mars as it did on Earth (McKay and Stoker in Rev. Geophys. 27:189-214, 1989). Conceivably, early autotrophic life on Mars, like early life on Earth, used irreversible enzymatically enhanced metabolic processes that would have fractionated stable isotopes of the elements C, N, S, and Fe. Several important assumptions are made when such isotope fractionations are used as a biomarker. The purpose of this article is two-fold: (1) to discuss these assumptions for the case of carbon and to summarize new insights in abiologic reactions, and (2) to discuss the use of other stable isotope systems as a potential biomarker. It is concluded that isotopic biomarker studies on Mars will encounter several important obstacles. In the case of carbon isotopes, the most important obstacle is the absence of a contemporary abiologic carbon reservoir (such as carbonate deposits on Earth) to act as isotopic standard. The presence of a contemporary abiologic sulfate reservoir (evaporite deposits) suggests that sulfur isotopes can be used as a potential biomarker for sulfate-reducing bacteria. The best approach for tracing ancient life on Mars will be to combine several biomarker approaches; to search for complexity, and to combine small-scale isotopic variations with chemical, mineralogical, and morphological observations. An example of such a study can be a layer-specific correlation between δ 13C and δ 34S within an ancient Martian evaporite, which morphologically resembles the typical setting of a shallow marine microbial mat.

  10. Boron isotope evidence for oceanic carbon dioxide leakage during the last deglaciation.

    PubMed

    Martínez-Botí, M A; Marino, G; Foster, G L; Ziveri, P; Henehan, M J; Rae, J W B; Mortyn, P G; Vance, D

    2015-02-12

    Atmospheric CO2 fluctuations over glacial-interglacial cycles remain a major challenge to our understanding of the carbon cycle and the climate system. Leading hypotheses put forward to explain glacial-interglacial atmospheric CO2 variations invoke changes in deep-ocean carbon storage, probably modulated by processes in the Southern Ocean, where much of the deep ocean is ventilated. A central aspect of such models is that, during deglaciations, an isolated glacial deep-ocean carbon reservoir is reconnected with the atmosphere, driving the atmospheric CO2 rise observed in ice-core records. However, direct documentation of changes in surface ocean carbon content and the associated transfer of carbon to the atmosphere during deglaciations has been hindered by the lack of proxy reconstructions that unambiguously reflect the oceanic carbonate system. Radiocarbon activity tracks changes in ocean ventilation, but not in ocean carbon content, whereas proxies that record increased deglacial upwelling do not constrain the proportion of upwelled carbon that is degassed relative to that which is taken up by the biological pump. Here we apply the boron isotope pH proxy in planktic foraminifera to two sediment cores from the sub-Antarctic Atlantic and the eastern equatorial Pacific as a more direct tracer of oceanic CO2 outgassing. We show that surface waters at both locations, which partly derive from deep water upwelled in the Southern Ocean, became a significant source of carbon to the atmosphere during the last deglaciation, when the concentration of atmospheric CO2 was increasing. This oceanic CO2 outgassing supports the view that the ventilation of a deep-ocean carbon reservoir in the Southern Ocean had a key role in the deglacial CO2 rise, although our results allow for the possibility that processes operating in other regions may also have been important for the glacial-interglacial ocean-atmosphere exchange of carbon.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. A 10-fold improvement in the precision of boron isotopic analysis by negative thermal ionization mass spectrometry.

    PubMed

    Shen, Jason Jiun-San; You, Chen-Feng

    2003-05-01

    Boron isotopes are potentially very important to cosmochemistry, geochemistry, and paleoceanography. However, the application has been hampered by the large sample required for positive thermal ionization mass spectrometry (PTIMS), and high mass fractionation for negative-TIMS (NTIMS). Running as BO(2)(-), NTIMS is very sensitive and requires only nanogram sized samples, but it has rather poor precision (approximately 0.7-2.0 per thousand) as a result of the larger mass fractionation associated with the relatively light ion. In contrast, running as the much heavier molecule of Cs(2)BO(2)(+), PTIMS usually achieves better precision around 0.1-0.4 per thousand. Moreover, there is a consistent 10 per thousand offset in the (11)B/(10)B ratio for NIST SRM 951 standard boric acid between the NTIMS and the certified value, but the cause of this offset is unclear. In this paper, we have adapted a technique we developed earlier to measure the (138)La/(139)La using LaO(+) (1) to improve the NTIMS technique for BO(2). We were able to correct for instrumental fractionation by measuring BO(2)(-) species not only at masses of 42 and 43, but also at 45, which enabled us to normalize (45)BO(2)/(43)BO(2) to an empirical (18)O/(16)O value. We found that both I(45)/I(42) = ((11)B(16)O(18)O/(10)B(16)O(16)O) and (I(43)/I(42))(C) = ((11)B(16)O(16)O/(10)B(16)O(16)O) vary linearly with (I(45)/I(43))(C) x 0.5 = ((11)B(16)O(18)O/(11)B(16)O(16)O) x 0.5 = (18)O/(16)O. In addition, different activators and different chemical forms of B yield different slopes for the fractionation lines. After normalizing (11)B(16)O(18)O/(11)B(16)O(16)O x 0.5 to a fixed (18)O/(16)O value, we obtained a mean (11)B/(10)B value of NIST SRM 951 that matches the NIST certified value at 4.0430 +/- 0.0015 (+/-0.36 per thousand, n = 11). As a result, our technique can achieve precision and accuracy comparable to that of PTIMS with only 1 per thousand of the sample required. This new NTIMS technique for B isotopes is

  16. 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.

  17. Broadband non-selective excitation of plutonium isotopes for isotope ratio measurements in resonance ionization mass spectrometry: a theoretical study.

    PubMed

    Sankari, M

    2012-10-15

    Making isotope ratio measurements with minimum isotope bias has always been a challenging task to mass spectrometrists, especially for the specific case of plutonium, owing to the strategic importance of the element. In order to use resonance ionization mass spectrometry (RIMS) as a tool for isotope ratio measurements, optimization of the various laser parameters and other atomic and system parameters is critical to minimize isotopic biases. Broadband simultaneous non-selective excitation of the isotopes of plutonium in the triple resonance excitation scheme with λ(1) = 420.77 nm, λ(2) = 847.28 nm, and λ(3) = 767.53 nm based on density matrix formalism has been theoretically computed for the determination of isotope ratios. The effects of the various laser parameters and other factors such as the atomization temperature and the dimensions of the atomic beam on the estimation of isotope ratios were studied. The effects of Doppler broadening, and time-dependent excitation parameters such as Rabi frequencies, ionization rate and the effect of non-Lorenztian lineshape have all been incorporated. The average laser powers and bandwidths for the three-excitation steps were evaluated for non-selective excitation. The laser intensity required to saturate the three-excitation steps were studied. The two-dimensional lineshape contour and its features were investigated, while the reversal of peak asymmetry of two-step and two-photon excitation peaks under these conditions is discussed. Optimized powers for the non-selective ionization of the three transitions were calculated as 545 mW, 150 mW and 545 mW and the laser bandwidth for all the three steps was ~20 GHz. The isotopic bias between the resonant and off-resonant isotope under the optimized conditions was no more than 9%, which is better than an earlier reported value. These optimized laser power and bandwidth conditions are better than in the earlier experimental work since these comprehensive calculations yield

  18. 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.

  19. Comparison of gas chromatography/isotope ratio mass spectrometry and liquid chromatography/isotope ratio mass spectrometry for carbon stable-isotope analysis of carbohydrates.

    PubMed

    Moerdijk-Poortvliet, Tanja C W; Schierbeek, Henk; Houtekamer, Marco; van Engeland, Tom; Derrien, Delphine; Stal, Lucas J; Boschker, Henricus T S

    2015-07-15

    We compared gas chromatography/isotope ratio mass spectrometry (GC/IRMS) and liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) for the measurement of δ(13)C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported. GC/IRMS with the aldonitrile penta-acetate (ANPA) derivatisation method was compared with LC/IRMS without derivatisation. A large number of glucose standards and a variety of natural samples were analysed for five neutral carbohydrates at natural abundance as well as at (13)C-enriched levels. Gas chromatography/chemical ionisation mass spectrometry (GC/CIMS) was applied to check for incomplete derivatisation of the carbohydrate, which would impair the accuracy of the GC/IRMS method. The LC/IRMS technique provided excellent precision (±0.08‰ and ±3.1‰ at natural abundance and enrichment levels, respectively) for the glucose standards and this technique proved to be superior to GC/IRMS (±0.62‰ and ±19.8‰ at natural abundance and enrichment levels, respectively). For GC/IRMS measurements the derivatisation correction and the conversion of carbohydrates into CO2 had a considerable effect on the measured δ(13)C values. However, we did not find any significant differences in the accuracy of the two techniques over the full range of natural δ(13)C abundances and (13)C-labelled glucose. The difference in the performance of GC/IRMS and LC/IRMS diminished when the δ(13)C values were measured in natural samples, because the chromatographic performance and background correction became critical factors, particularly for LC/IRMS. The derivatisation of carbohydrates for the GC/IRMS method was complete. Although both LC/IRMS and GC/IRMS are reliable techniques for compound-specific stable carbon isotope analysis of carbohydrates (provided that derivatisation is complete and the

  20. 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.

  1. 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.

  2. 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.

  3. Stable hydrogen and oxygen isotope ratios of bottled waters of the world.

    PubMed

    Bowen, Gabriel J; Winter, David A; Spero, Howard J; Zierenberg, Robert A; Reeder, Mathew D; Cerling, Thure E; Ehleringer, James R

    2005-01-01

    Bottled and packaged waters are an increasingly significant component of the human diet. These products are regulated at the regional, national, and international levels, and determining the authenticity of marketing and labeling claims represents a challenge to regulatory agencies. Here, we present a dataset of stable isotope ratios for bottled waters sampled worldwide, and consider potential applications of such data for regulatory, forensic and geochemical standardization applications. The hydrogen and oxygen isotope ratios of 234 samples of bottled water range from -147 per thousand to +15 per thousand and from -19.1 per thousand to +3.0 per thousand, respectively. These values fall within and span most of the normal range for meteoric waters, indicating that these commercially available products represent a source of waters for use as laboratory working standards in applications requiring standardization over a large range of isotope ratios. The measured values of bottled water samples cluster along the global meteoric water line, suggesting that bottled water isotope ratios preserve information about the water sources from which they were derived. Using the dataset, we demonstrate how bottled water isotope ratios provide evidence for substantial evaporative enrichment of water sources prior to bottling and for the marketing of waters derived from mountain and lowland sources under the same name. Comparison of bottled water isotope ratios with natural environmental water isotope ratios demonstrates that on average the isotopic composition of bottled water tends to be similar to the composition of naturally available local water sources, suggesting that in many cases bottled water need not be considered as an isotopically distinct component of the human diet. Our findings suggest that stable isotope ratios of bottled water have the power to distinguish ultimate (e.g., recharge) and proximal (e.g., reservoir) sources of bottled water and constitute a potential

  4. Non-chondritic iron isotope ratios in planetary mantles as a result of core formation

    NASA Astrophysics Data System (ADS)

    Elardo, Stephen M.; Shahar, Anat

    2017-02-01

    Information about the materials and conditions involved in planetary formation and differentiation in the early Solar System is recorded in iron isotope ratios. Samples from Earth, the Moon, Mars and the asteroid Vesta reveal significant variations in iron isotope ratios, but the sources of these variations remain uncertain. Here we present experiments that demonstrate that under the conditions of planetary core formation expected for the Moon, Mars and Vesta, iron isotopes fractionate between metal and silicate due to the presence of nickel, and enrich the bodies' mantles in isotopically light iron. However, the effect of nickel diminishes at higher temperatures: under conditions expected for Earth's core formation, we infer little fractionation of iron isotopes. From our experimental results and existing conceptual models of magma ocean crystallization and mantle partial melting, we find that nickel-induced fractionation can explain iron isotope variability found in planetary samples without invoking nebular or accretionary processes. We suggest that near-chondritic iron isotope ratios of basalts from Mars and Vesta, as well as the most primitive lunar basalts, were achieved by melting of isotopically light mantles, whereas the heavy iron isotope ratios of terrestrial ocean floor basalts are the result of melting of near-chondritic Earth mantle.

  5. 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).

  6. Reply to the comment on 'Boron content and isotopic composition of oceanic basalts: Geochemical and cosmochemical implications'

    NASA Astrophysics Data System (ADS)

    Chaussidon, Marc; Jambon, Albert

    1994-12-01

    Chen-Feng You questions some of our interpretations of the B contents and delta B-11 values of oceanic basalts. His comments can be summarized in three points: (1) He emphasizes the importance of sediments as a B carrier, which should be taken into account in any budget calculation. He suggests that our estimated amount of boron subducted into the mantle is incorrect. (2) He quotes unpublished experimental results indicating that sedimentary boron is partly leached from a hemi-pelagic sediment at moderate temperatures (T less than or = 150 C) leaving a B-depleted residue isotopically fractionated to low delta B-11 values. (3) He further argues that Boron abundance and delta B-11 values at both Hawaii and the Halmahera arc could be explained by the incorporation of such fluids (i.e., released during subduction). Although we do think that the type of experiment described by You is effectively lacking at the moment and is of great potential for the understanding of B geochemical cycle, we also think that: (1) the experiments of You are insufficient to elucidate the behavior of B during subduction; and (2) two points of our work were misunderstood. We discuss successively the three points raised by You.

  7. 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.

  8. 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

  9. 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.

  10. In-Vivo Zinc Metabolism by Isotope Ratio Mass Spectrometry

    USDA-ARS?s Scientific Manuscript database

    The purpose of this chapter is to highlight some of the methodological and technical issues surrounding the in vivo use of stable isotopes and to provide examples of how such studies have advanced our knowledge of human zinc metabolism. The advantages and disadvantages of the currently available in...

  11. 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.

  12. 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.

  13. A balloon measurement of the isotopic composition of galactic cosmic ray boron, carbon and nitrogen. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Zumberge, J. F.

    1981-01-01

    The isotopic compositions of galactic cosmic ray boron, carbon, and nitrogen were measured at energies near 300 MeV amu, using a balloon-borne instrument at an atmospheric depth of approximately 5 g/sq cm. The calibrations of the detectors comprising the instrument are described. The saturation properties of the cesium iodide scintillators used for measurement of particle energy are studied in the context of analyzing the data for mass. The achieved rms mass resolution varies from approximately 0.3 amu at boron to approximately 0.5 amu at nitrogen, consistent with a theoretical analysis of the contributing factors. Corrected for detector interactions and the effects of the residual atmosphere the results are B-10/B=0.33 (+0.17, -0.11), C-13/C=0.06 (+0.13, -0.11), and N-15/N=0.42 (+0.19, -0.17). A model of galactic propagation and solar modulation is described. Assuming a cosmic ray source composition of solar-like isotopic abundances, the model predicts abundances near Earth consistent with the measurements.

  14. 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.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    Compositional changes, dehydration reactions and fluid flow in subducted sediments influence seismogenesis and arc magmatism in subduction zones. To identify fluid flow and water-rock interaction processes in the western Nankai Trough subduction zone (SW Japan) we analyzed boron concentration and boron isotope composition (δ11B) of pore fluids sampled across the subduction zone forearc from depths of up to ∼922 m below seafloor during four Integrated Ocean Drilling Program (IODP) Expeditions. The major structural regimes that were sampled by coring include: (1) sedimentary inputs, (2) the frontal thrust zone, (3) the megasplay fault zone, and (4) the forearc basin. From mass balance consideration we find that consumption of boron (B) by ash alteration and desorption of B from the solid phase, mediated by organic matter degradation, produces a net decrease in B concentrations with depth down to ∼120 μM and variable δ11B values in the range of ∼+20‰ and +49‰. Interstitial water in sediments on the incoming oceanic plate are influenced by more efficient mobilization of exchangeable B from the solid phase due to higher temperatures and alteration of the oceanic crust that acts as a sink for 10B. At the tip of the megasplay fault zone, elevated B concentration and B isotopic composition suggest that underthrust coarse-grained slope sediments provide a pathway for fluids out of the upper (<2 km) accretionary prism. Silt and sand layers in the underthrust section of the downgoing plate favor fluid escape in seaward direction from depths equivalent to the temperature range of 60-150 °C. At both locations the δ11B signature evolves during updip migration through re-adsorption. Mass balance considerations suggest a shallower fluid source depth compared to pore fluids sampled previously near the décollement zone along the central portion of the Nankai margin.

  17. 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.

  18. Stable isotope ratios and reforestation potential in Acacia koa populations on Hawai'i

    Treesearch

    Shaneka Lawson; Carrie Pike

    2017-01-01

    Stable carbon and nitrogen isotopes can be influenced by a multitude of factors including elevation, precipitation rate, season, and temperature. This work examined variability in foliar stable carbon (δ13C) and nitrogen (δ15N) isotope ratios of koa (Acacia koa) across 17 sites on Hawai'i Island, delineated by elevation and precipitation...

  19. USING MUSSEL ISOTOPE RATIOS TO ASSESS ANTHROPOGEN NITROGEN INPUTS TO COASTAL ECOSYSTEMS

    EPA Science Inventory

    The stable nitrogen isotope ratio in ribbed mussel (Geukensia demissus) tissue was investigated as an indicator of the source of nitrogen inputs to coastal salt marshes. Mussels fed a diet of 15N enriched algae in the laboratory showed an increase in tissue nitrogen isotope rati...

  20. Insights into Wilson's Warbler migration from analyses of hydrogen stable-isotope ratios

    Treesearch

    Jeffrey F. Kelly; Viorel Atudorei; Zachary D. Sharp; Deborah M. Finch

    2002-01-01

    Our ability to link the breeding locations of individual passerines to migration stopover sites and wintering locations is limited. Stable isotopes of hydrogen contained in bird feathers have recently shown potential in this regard. We measured hydrogen stable-isotope ratios (deltaD) of feathers from breeding, migrating, and wintering Wilson's Warblers. Analyses...

  1. 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. 2009 John Wiley & Sons, Ltd.

  2. On-line measurement of intramolecular carbon isotope distribution of acetic acid by continuous-flow isotope ratio mass spectrometry.

    PubMed

    Yamada, Keita; Tanaka, Misato; Nakagawa, Fumiko; Yoshida, Naohiro

    2002-01-01

    Molecular and intramolecular carbon isotope measurements of acetic acid present in natural environments have been performed by off-line procedures. The off-line method is complicated and time-consuming and requires micromolar to millimolar amounts of sample. This limits geochemical isotopic studies, especially at the intramolecular level, on acetic acid present in natural samples. Here, we examine an on-line measurement of intramolecular carbon isotope distribution of acetic acid using continuous-flow isotope ratio mass spectrometry (CF-IRMS) coupled with an on-line pyrolysis system. This is achieved by measurement of the respective carbon isotope ratios of CH4 and CO2 produced by on-line pyrolysis of acetic acid. Results for authentic standards of pure acetic acid demonstrated the practicality of this on-line method, although the carbon isotope ratio of the methyl group could not be determined directly. The precision of the carbon isotope measurements was 0.4 per thousand (1sigma). The carbon isotope distribution determined by the on-line method was identical to that determined by the conventional off-line method within analytical error. The advantages of the on-line method compared with the conventional off-line method are that it is less laborious, requires less analytical time (less than one hour per sample) and, most importantly, uses smaller sample sizes (ca. 10 nanomole). An application of this on-line method to natural geochemical samples will provide an insight into the geochemical cycle of acetic acid. Copyright 2002 John Wiley & Sons, Ltd.

  3. 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.

  4. Chemical and boron isotopic compositions of tourmaline from the Paleoproterozoic Houxianyu borate deposit, NE China: Implications for the origin of borate deposit

    NASA Astrophysics Data System (ADS)

    Yan, Xue-long; Chen, Bin

    2014-11-01

    The Houxianyu borate deposit in northeastern China is one of the largest boron sources of China, hosted mainly in the Paleoproterozoic meta-volcanic and sedimentary rocks (known as the Liaohe Group) that are characterized by high boron concentrations. The borate ore-body has intimate spatial relationship with the Mg-rich carbonates/silicates of the Group, with fine-grained gneisses (meta-felsic volcanic rocks) as main country rocks. The presence of abundant tourmalinites and tourmaline-rich quartz veins in the borate orebody provides an opportunity to study the origin of boron, the nature of ore-forming fluids, and possible mineralization mechanism. We report the chemical and boron isotopic compositions of tourmalines from the tourmaline-rich rocks in the borate deposit and from the tourmaline-bearing fine-grained gneisses. Tourmalines from the fine-grained gneisses are chemically homogeneous, showing relatively high Fe and Na and low Mg, with δ11B values in a narrow range from +1.22‰ to +2.63‰. Tourmalines from the tourmaline-rich rocks, however, commonly show compositional zoning, with an irregular detrital core and a euhedral overgrowth, and have significantly higher Mg, REE (and more pronounced positive Eu anomalies), V (229-1852 ppm) and Sr (208-1191 ppm) than those from the fine-grained gneisses. They show varied B isotope values ranging from +4.51‰ to +12.43‰, which plot intermediate between those of the terrigenous sediments and arc rocks with low boron isotope values (as represented by the δ11B = +1.22‰ to +2.63‰ of the fine-grained gneisses of this study) and those of marine carbonates and evaporates with high boron isotope values. In addition, the rim of the zoned tourmaline shows notably higher Mg, Ti, V, Sn, and Pb, and REE (particularly LREEs), but lower Fe, Co, Cr, Ni, Zn, Mn, and lower δ11B values than the core. These data suggest that (1) the sources of boron of the borate ore-body are mainly the Paleoproterozoic meta-volcanic and

  5. 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.

  6. 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...

  7. 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...

  8. Classification of nine malathion emulsion samples by using carbon isotope ratios and the ratio of organic solvents.

    PubMed

    Suto, Nana; Kawashima, Hiroto

    2017-01-01

    The compound specific isotope analysis is nowadays an important and powerful tool in geochemical, environmental and forensics field. On November 2013, Aqli Foods Corporation in Japan dealt with complaints about stench from frozen foods produced. Subsequently, very high concentrations of organophosphorus pesticide as malathion, ethylbenzene and xylene were detected in recovered frozen foods. In particular case, we present the method to measure the stable carbon isotope ratio (δ(13)C) of nine malathion emulsion pesticides using gas chromatography/isotope ratio mass spectrometry (GC/IRMS) to identify the source. The δ(13)C values of malathion ranged from -30.6‰ to -29.5‰. Because malathion used in all malathion emulsions sold in Japan is imported from the same overseas company, Cheminova, Denmark. The δ(13)C values of ethylbenzene ranged from -28.2‰ to -20.8‰ and those of m,p-xylene from -28.7‰ to -25.2‰. The differences in the δ(13)C values may be because of the material itself and chemical processing. We also determined the ratio of ethylbenzene to m,p-xylene and finally categorized the nine malathion samples into five groups on the basis of this ratio and the δ(13)C values of ethylbenzene and m,p-xylene. The results of isotopic fractionation during volatilization (refrigerate, room temperature and incubator) was negligible small. Copyright © 2016 The Chartered Society of Forensic Sciences. Published by Elsevier Ireland Ltd. All rights reserved.

  9. Graphite Isotope Ratio Method Development Report: Irradiation Test Demonstration of Uranium as a Low Fluence Indicator

    SciTech Connect

    Reid, B.D.; Gerlach, D.C.; Love, E.F.; McNeece, J.P.; Livingston, J.V.; Greenwood, L.R.; Petersen, S.L.; Morgan, W.C.

    1999-10-20

    This report describes an irradiation test designed to investigate the suitability of uranium as a graphite isotope ratio method (GIRM) low fluence indicator. GIRM is a demonstrated concept that gives a graphite-moderated reactor's lifetime production based on measuring changes in the isotopic ratio of elements known to exist in trace quantities within reactor-grade graphite. Appendix I of this report provides a tutorial on the GIRM concept.

  10. 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.

  11. 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.

  12. Preliminary results of oxygen isotope ratio measurement with a particle-gamma coincidence method

    NASA Astrophysics Data System (ADS)

    Borysiuk, Maciek; Kristiansson, Per; Ros, Linus; Abdel, Nassem S.; Elfman, Mikael; Nilsson, Charlotta; Pallon, Jan

    2015-04-01

    The possibility to study variations in the oxygen isotopic ratio with photon tagged nuclear reaction analysis (pNRA) is evaluated in the current work. The experiment described in the article was performed at Lund Ion Beam Analysis Facility (LIBAF) with a 2 MeV deuteron beam. Isotopic fractionation of light elements such as carbon, oxygen and nitrogen is the basis of many analytical tools in hydrology, geology, paleobiology and paleogeology. IBA methods provide one possible tool for measurement of isotopic content. During this experimental run we focused on measurement of the oxygen isotopic ratio. The measurement of stable isotopes of oxygen has a number of applications; the particular one driving the current investigation belongs to the field of astrogeology and specifically evaluation of fossil extraterrestrial material. There are three stable isotopes of oxygen: 16O, 17O and 18O. We procured samples highly enriched with all three isotopes. Isotopes 16O and 18O were easily detected in the enriched samples, but no significant signal from 17O was detected in the same samples. The measured yield was too low to detect 18O in a sample with natural abundances of oxygen isotopes, at least in the current experimental setup, but the spectral line from the reaction with 16O was clearly visible.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  14. 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.

  15. Observations and sources of carbon and nitrogen isotope ratio variation of pentaerythritol tetranitrate (PETN).

    PubMed

    Howa, John D; Lott, Michael J; Ehleringer, James R

    2014-11-01

    Isotope ratio analysis allows forensic investigators to discriminate materials that are chemically identical but differ in their isotope ratios. Here we focused on the discrimination of pentaerythritol tetranitrate (PETN), an explosive with military and civilian applications, using carbon (δ(13)C) and nitrogen (δ(15)N) isotope ratios. Our goal was to understand some of the factors influencing the isotope ratios of commercially manufactured PETN. PETN was isolated from bulk explosives using preparative HPLC, which reduced chemical and isotopic within-sample variability. We observed isotope ratio variation in a survey of 175 PETN samples from 22 manufacturing facilities, with δ(13)C values ranging from -49.7‰ to -28.0‰ and δ(15)N values ranging from -48.6‰ to +6.2‰. Both within-sample variability and variation of PETN within an explosive block were much smaller than between-sample variations. Isotopic ratios of PETN were shown to discriminate explosive blocks from the same manufacturer, whereas explosive component composition measurements by HPLC were not able to do so. Using samples collected from three industrial PETN manufacturers, we investigated the isotopic relationship between PETN and its reactants, pentaerythritol (PE) and nitric acid. Our observations showed that δ(13)C values of PETN were indistinguishable from that of the reactant pentaerythritol. Isotopic separation between nitric acid and PETN was consistent within each sampled manufacturer but differed among manufacturers, and was likely dependent upon reaction conditions. These data indicate that δ(13)C variation in PETN is dependent on δ(13)C variation of PE supplies, while δ(15)N variation in PETN is due to both nitric acid δ(15)N and reaction conditions. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Ratios for light-element isotopes standardized for better interlaboratory comparison

    NASA Astrophysics Data System (ADS)

    Coplen, T. B.; De Bièvre, P.; Krouse, H. R.; Vocke, R. D., Jr.; Gröning, M.; Rozanski, K.

    Stable isotope-ratio measurements of the light elements have been used in increasingly important ways to understand processes in geochemistry, hydrology, oceanography, atmospheric sciences, environmental studies, and many other fields. Progress in these fields requires better precision and reproducibility of stable isotope-ratio measurements. Some laboratories are claiming accuracies of 0.02‰ or better for δ13C and δ180. However, δ13C and δ180 analyses of the same sample by different laboratories can differ by more than 0.3‰. Recognizing that isotopic analyses of the same homogeneous material reported from different credible laboratories should yield the same isotopic composition within the uncertainty of the measurements, the International Atomic Energy Agency (IAEA) held an Advisory Group Meeting on stable isotope reference and intercomparison materials for light elements in Vienna from December 11 to 14, 1995.

  1. 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.

  2. 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

  3. When other separation techniques fail: compound-specific carbon isotope ratio analysis of sulfonamide containing pharmaceuticals by high-temperature-liquid chromatography-isotope ratio mass spectrometry.

    PubMed

    Kujawinski, Dorothea M; Zhang, Lijun; Schmidt, Torsten C; Jochmann, Maik A

    2012-09-18

    Compound-specific isotope analysis (CISA) of nonvolatile analytes has been enabled by the introduction of the first commercial interface to hyphenate liquid chromatography with an isotope ratio mass spectrometer (LC-IRMS) in 2004, yet carbon isotope analysis of unpolar and moderately polar compounds is still a challenging task since only water as the eluent and no organic modifiers can be used to drive the separation in LC. The only way to increase the elution strength of aqueous eluents in reversed phase LC is the application of high temperatures to the mobile and stationary phases (HT-LC-IRMS). In this context we present the first method to determine carbon isotope ratios of pharmaceuticals that cannot be separated by already existing separation techniques for LC-IRMS, such as reversed phase chromatography at normal temperatures, ion-chromatography, and mixed mode chomatography. The pharmaceutical group of sulfonamides, which is generally mixed with trimethoprim in pharmaceutical products, has been chosen as probe compounds. Substance amounts as low as 0.3 μg are sufficient to perform a precise analysis. The successful applicability and reproducibility of this method is shown by the analysis of real pharmaceutical samples. The method provides the first tool to study the pharmaceutical authenticity as well as degradation and mobility of such substances in the environment by using the stable isotopic signature of these compounds.

  4. Model studies directed toward the application of boron neutron capture therapy to rheumatoid arthritis: Boron delivery by liposomes in rat collagen-induced arthritis

    PubMed Central

    Watson-Clark, Rachel A.; Banquerigo, Mona Lisa; Shelly, Kenneth; Hawthorne, M. Frederick; Brahn, Ernest

    1998-01-01

    The application of boron neutron capture therapy to rheumatoid arthritis requires the selective delivery of the boron-10 isotope to the synovitic tissue. The use of liposomes as a boron delivery method has been explored through the measurement of the time course biodistribution of boron in rats with collagen-induced arthritis (CIA). Small unilamellar vesicles were composed of a 1:1 mixture of distearoylphosphatidylcholine and cholesterol, incorporated K[nido-7-CH3(CH2)15-7,8-C2B9H11] as an addend in the lipid bilayer and encapsulated Na3[a2-B20H17NH2CH2CH2NH2] in the aqueous core. The tissue concentration of boron delivered by liposomes was determined by inductively coupled plasma–atomic emission spectroscopy after intravenous injection of liposome suspensions into Louvain rats with CIA. With the low injected doses of boron used [13–18 mg of boron per kg (body weight)], the peak boron concentration observed in arthritic synovium was 29 μg of boron per g of tissue. The highest synovium/blood boron ratio observed was 3.0, when the synovial boron concentration was 22 μg of boron per g of tissue. In an attempt to increase the synovium/blood boron ratio by lowering the blood boron concentration, a liposomal formulation characterized by a shorter blood clearance time was examined. Thus, the biodistribution of liposomes with additional K[nido-7-CH3(CH2)15-7,8-C2B9H11] incorporated in the vesicle membrane not only demonstrated more rapid blood clearance and slightly higher synovium/blood boron ratios but also exhibited reduced boron uptake in synovial tissue. These studies with boron neutron capture therapy for CIA suggest that this form of therapy may be feasible in the treatment of rheumatoid arthritis. PMID:9482920

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Sulphur isotope ratios in the Canyon Diablo metallic spheroids

    NASA Astrophysics Data System (ADS)

    McEwing, C. E.; Rees, C. E.; Thode, H. G.

    1983-09-01

    Nininger (1956) has discovered metallic spheroids in the soil surrounding Meteor Crater in Arizona. Nininger suggested that the spheroids condensed from the center of a homogeneous explosion-produced metallic vapor cloud. The present investigation is concerned with measurements of sulfur contents and delta S-34 values of metallic spheroids from the vicinity of Meteor Crater. It is found that the small metallic spheroids have lower sulfur contents and higher delta S-34 values than do the large spheroids. It is concluded that the observed isotopic patterns are unlikely to have arisen during desulfurization of the metallic liquid from which the spheroids were formed or during high temperature oxidation or the spheroids. The most likely process for the production of the observed delta S-34 values and sulfur contents is low temperature oxidation reactions experienced by the spheroids during their surface exposure following formation.

  16. Site-specific carbon isotope analysis of aromatic carboxylic acids by elemental analysis/pyrolysis/isotope ratio mass spectrometry.

    PubMed

    Oba, Yasuhiro; Naraoka, Hiroshi

    2006-01-01

    Site-specific carbon isotope composition of organic compounds can provide useful information on their origin and history in natural environments. Site-specific isotope analyses of small amounts of organic compounds (sub-nanomolar level), such as short-chain carboxylic acids and amino acid analogues, have been performed using gas chromatography/pyrolysis/isotope ratio mass spectrometry (GC/pyrolysis/IRMS). These analyses were previously limited to volatile compounds. In this study, site-specific carbon isotope analysis has been developed for non-volatile aromatic carboxylic acids at sub-micromolar level by decarboxylation using a continuous flow elemental analysis (EA)/pyrolysis/IRMS technique. Benzoic acid, 2-naphthylacetic acid and 1-pyrenecarboxylic acid were pyrolyzed at 500-1000 degrees C by EA/pyrolysis/IRMS to produce CO2 for delta13C measurement of the carboxyl group. These three aromatic acids were most efficiently pyrolyzed at 750 degrees C. Conventional sealed-tube pyrolysis was also conducted for comparison. The delta13C values of CO2 generated by the continuous flow technique were within 1.0 per thousand of those performed by the conventional technique, indicating that the new continuous flow technique can accurately analyze the carbon isotopic composition of the carboxyl group in aromatic carboxylic acids. The new continuous flow technique is simple, rapid and uses small sample sizes, so this technique will be useful for characterizing the isotopic signature of carboxyl groups in organic compounds. Copyright 2006 John Wiley & Sons, Ltd.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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 paper

  2. Boron isotope and geochemical evidence for the origin of Urania and Bannock brines at the eastern Mediterranean: effect of water-rock interactions

    NASA Astrophysics Data System (ADS)

    Vengosh, Avner; De Lange, Gert J.; Starinsky, Abraham

    1998-10-01

    The origin of hypersaline brines from Urania and Bannock deep anoxic basins in the eastern Mediterranean Sea has been investigated by integrating geochemical data and boron isotopic ratios. Bottom brines from Urania basin have chloride contents up to 4200 mmole/kg H 2O and a marine Na/Cl ratio (0.87). All the other ionic ratios are different from the marine ratios and show a relative enrichment in Ca, K, Br, and B and depletion in Mg and SO 4, as normalized to the chloride ion. The δ 11B values of the Urania brines (δ 11B = 29.8 ± 2.9‰; n = 7) are lower than that of Mediterranean seawater (39‰). The concentrations of Cl and Na, which make up 95% of the total dissolved ions (in molal units), suggest that the Urania brines were derived from eightfold evaporated seawater. The relative enrichment of Ca and depletion of Mg and SO 4 reflect dolomitization, gypsum precipitation, and sulfate reduction processes which modified the original evaporated seawater while the brines were entrapped as interstitial waters in the sedimentary section of the Mediterranean. The relative enrichments of Br, B, and K, and the low δ 11B value of the Urania brines suggest high-temperatures interactions of the evaporated sea water with sediments. Mass-balance calculations suggest that desorption of exchangeable B from the sediments (δ 11B ˜ 20‰) modified the marine B isotopic composition of the original eightfold evaporated seawater. Potassium was also leached from clay minerals whereas Br was contributed from degradation of organic matter in the sediments. This is consistent with a thermal anomaly (up to 45°C) recorded at depth in the region of Urania basin. In contrast, bottom brines and shallow interstitial fluids from Bannock basin with low temperatures (15°C) show marine δ 11B (δ 11B = 39.6 ± 2.8‰; n = 5; 38.5 ± 2.2‰; n = 5, respectively) and B/Cl ratios (7 × 10 -4). The B isotope data confirm that the Bannock brines were derived from twelvefold evaporated seawater

  3. Boron isotope fractionation in groundwaters as an indicator of past permafrost conditions in the fractured crystalline bedrock of the fennoscandian shield.

    PubMed

    Casanova, Joël; Négrel, Philippe; Blomqvist, Runar

    2005-01-01

    The Fennoscandian Shield has been subjected to several glaciations over the past million years, the last of which (Weichselian Ice Age) ended only at about 10Ka. Here we used boron isotopes and B contents to (a) establish the degree of water-rock interaction (WRI) and (b) clarify freezing processes within groundwaters from the Aspo site in Sweden and from various sites in Finland. The high delta(11)B values recorded by all groundwaters (up to 51.9 per thousand) including diluted, boron-poor, inland groundwaters suggest selective uptake of (10)B into ice related to freezing processes under permafrost conditions. According to co-existing ice and residual brines in a Canadian frozen mine, this fractionation process, enhanced by Rayleigh fractionation, can generate a natural field of isotopic variation around 60 per thousand and provides a new application of B isotope that makes possible to easily characterise groundwaters that underwent past permafrost conditions.

  4. 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.

  5. 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

  6. 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

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

    PubMed

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

    2012-11-01

    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 (236)U/(238)U 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 (234)U/(238)U and (235)U/(238)U ratios. Experimental results obtained for (236)U/(238)U isotope ratios deviated by less than -2.5% from the certified values. Expanded relative total combined standard uncertainties U(c) (k = 2) of 2.6%, 1.4% and 5.8% were calculated for (234)U/(238)U, (235)U/(238)U and (236)U/(238)U, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. 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

  9. 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.

  10. Boron Isotopic Composition Correlates with Ultra-Structure in a - Sea Coral Lophelia Pertusa: Implications for Biomineralization and - PH

    NASA Astrophysics Data System (ADS)

    Blamart, D.; Rollion-Bard, C.; Meibom, A.; Cuif, J.; Juillet-Leclerc, A.; Dauphin, Y.; Douarin, M.

    2007-12-01

    The geochemistry (stable isotopes and trace elements) of biogenic carbonates has been widely used for more than fifty years to reconstruct past climatic variability. During this time, the studies were mainly based on bulk sampling limiting sometimes the interpretations of the geochemical data as paleoclimatic proxies. Recently, high spatial resolution sampling techniques, such as micro-mill and SIMS, have been employed in the study of C, O and B isotopic compositions and trace elements (Mg, Sr) in the skeletons of a variety of (deep-sea) coral species. These studies have documented dramatic 'vital effects' and uncovered a systematic relationship between skeletal ultra-structure and stable isotopic composition. The formation of skeleton corals follows a universal two-step growth process. At the tips of the skeletal structures, the mineralizing cell layer produces centers of calcification (COC) or, equivalently, Early Mineralization Zone (EMZ). These EMZ are subsequently overgrown by fibrous aragonite(FA) consisting of cyclically added layers. The EMZ are characterized by systematically lighter C and O isotopic compositions compared with the adjacent FA. A number of geochemical models have been proposed, in which this systematic stable isotopic difference between EMZ and FA is ascribed to a biologically induced variation in the pH of a proposed Extra-cytoplasmic Calcifying Fluid (ECF) reservoir. In these models, relatively high pH conditions during the formation of EMZ result in relatively light C and O isotopic compositions compared with FA, which form under generally lower pH conditions. A direct test of such models would be possible if the Boron isotopic composition, which is pH sensitive, of EMZ and FA could be measured. We performed ion microprobe d11B measurements for EMZ and FA in Lophelia pertusa, a deep-sea coral common in the North-East Atlantic Ocean. We observe a systematic difference in B isotopic composition between the EMZ and FA skeleton. In EMZ, the

  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. Global spatial distributions of nitrogen and carbon stable isotope ratios of modern human hair.

    PubMed

    Hülsemann, Frank; Lehn, Christine; Schneider, Sabine; Jackson, Glen; Hill, Sarah; Rossmann, Andreas; Scheid, Nicole; Dunn, Philip J H; Flenker, Ulrich; Schänzer, Wilhelm

    2015-11-30

    Natural stable carbon (δ(13)C) and nitrogen isotope ratios (δ(15)N) of humans are related to individual dietary habits and environmental and physiological factors. In forensic science the stable isotope ratios of human remains such as hair and nail are used for geographical allocation. Thus, knowledge of the global spatial distribution of human δ(13)C and δ(15)N values is an essential component in the interpretation of stable isotope analytical results. No substantial global datasets of human stable isotope ratios are currently available, although the amount of available (published) data has increased within recent years. We have herein summarised the published data on human global δ(13)C andδ(15)N values (around 3600 samples) and added experimental values of more than 400 additional worldwide human hair and nail samples. In order to summarise isotope ratios for hair and nail samples correction factors were determined. The current available dataset of human stable isotope ratios is biased towards Europe and North America with only limited data for countries in Africa, Central and South America and Southeast Asia. The global spatial distribution of carbon isotopes is related to latitude and supports the fact that human δ(13)C values are dominated by the amount of C4 plants in the diet, either due to direct ingestion as plant food, or by its use as animal feed. In contrast, the global spatial distribution of human δ(15)N values is apparently not exclusively related to the amount of fish or meat ingested, but also to environmental factors that influence agricultural production. There are still a large proportion of countries, especially in Africa, where there are no available data for human carbon and nitrogen isotope ratios. Although the interpretation of modern human carbon isotope ratios at the global scale is quite possible, and correlates with the latitude, the potential influences of extrinsic and/or intrinsic factors on human nitrogen isotope ratios

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

    PubMed

    Coplen, Tyler B

    2011-09-15

    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. Published in 2011 by John Wiley & Sons, Ltd.

  14. 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.

  15. 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. Copyright © 2010 John Wiley & Sons, Ltd.

  16. Application of stable isotope ratio analysis for biodegradation monitoring in groundwater

    USGS Publications Warehouse

    Hatzinger, Paul B.; Böhlke, John Karl; Sturchio, Neil C.

    2013-01-01

    Stable isotope ratio analysis is increasingly being applied as a tool to detect, understand, and quantify biodegradation of organic and inorganic contaminants in groundwater. An important feature of this approach is that it allows degradative losses of contaminants to be distinguished from those caused by non-destructive processes such as dilution, dispersion, and sorption. Recent advances in analytical techniques, and new approaches for interpreting stable isotope data, have expanded the utility of this method while also exposing complications and ambiguities that must be considered in data interpretations. Isotopic analyses of multiple elements in a compound, and multiple compounds in the environment, are being used to distinguish biodegradative pathways by their characteristic isotope effects. Numerical models of contaminant transport, degradation pathways, and isotopic composition are improving quantitative estimates of in situ contaminant degradation rates under realistic environmental conditions.

  17. STABLE ISOTOPE RATIOS IN ARCHIVED STRIPED BASS SCALES

    EPA Science Inventory

    In recent years fishermen and scientists have noted that striped bass caught along the East Coast of the United States have reduced weight to length ratios with many of the fish caught in Chesapeake Bay exhibiting skin lesions. Several theories have been suggested to explain thes...

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

    USDA-ARS?s Scientific Manuscript database

    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 ...

  19. Insights into Ocean Acidification During the Middle Eocene Climatic Optimum from Boron Isotopes at Southern Ocean Site 738

    NASA Astrophysics Data System (ADS)

    Moebius, I.; Hoenisch, B.; Friedrich, O.

    2015-12-01

    The Middle Eocene Climatic Optimum (MECO) is a ~650-kyr interval of global warming, with a brief ~50 ky long peak warming interval, and an abrupt termination. Deep sea and surface ocean temperature evolution across this interval are fairly well constrained, but thus far we have little understanding of the mechanisms responsible for the gradual warming and rapid recovery. Carbonate mass accumulation rates suggest a shoaling of the carbonate compensation depth, and studies on alkenones indicate increasing atmospheric CO2 levels during the MECO. This suggests an increase in surface ocean CO2, and consequently ocean acidification. However, the severity and timing of the proposed ocean acidification with respect to the onset, peak warming and the termination are currently not well resolved. The boron isotopic composition (δ11B) recorded in planktic foraminifer shells offers an opportunity to infer oceanic pH across this interval. We are working on a boron isotope reconstruction from Southern Ocean IODP site 738 and South Atlantic IODP site 1263, covering 42.0 to 38.5 Ma. These sites are characterized by good carbonate preservation and well-defined age models have been established. Additionally, ecology, nutrient content and bottom-water oxygenation have been shown to change significantly across the event towards a more eutrophic, periodically oxygen-depleted environment supporting different biological communities. We selected the planktic foraminifera species Acarinina spinuloinflata for this study because it is symbiont-bearing, suggesting a near-surface habitat and little vertical migration in the water column, and because of its abundance in the samples. δ11B data will be translated to surface ocean pH and atmospheric pCO2 will be approximated to refine knowledge about the carbon cycle during this time. Parallel analysis of two core sites will help to evaluate the tenacity of the data.

  20. 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.

  1. 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

  2. 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.

  3. The influence of mixing on stable isotope ratios in porous media: A revised Rayleigh model

    NASA Astrophysics Data System (ADS)

    Druhan, Jennifer L.; Maher, Kate

    2017-02-01

    For an irreversible reaction, the Rayleigh or distillation-type relationship between stable isotope enrichment and reactant concentration is compromised if fluid samples are characterized by a range of water ages or different extents of reaction progress. Such mixed samples are rarely avoided in the standard methods of sampling fluid from natural porous media. As a result, application of a Rayleigh model to stable isotope ratios measured in aquifers commonly requires a diminished or effective fractionation factor relative to the intrinsic value obtained in the absence of transport effects. Thus, quantitative application of intrinsic parameter values to a fractionating reaction occurring in porous media flow requires revision to the functional form of the relationship between reactant concentration and isotope fractionation. Here we derive a series of analytical solutions for the relationship between fractionation and flow subject to nonuniform fluid travel time distributions. These solutions are unique from previous approaches in that they avoid the use of a dispersion coefficient. The results are demonstrated against multicomponent reactive transport simulations of stable isotope fractionation in homogeneous and spatially correlated heterogeneous flow fields, and applied to a data set of stable chromium (Cr) isotope enrichment obtained from a contaminated aquifer. We show that the flux-weighted isotope ratio of a solute is more sensitive to the effects of physical heterogeneity than solute concentrations. Our results support an updated functional form of the traditional Rayleigh model that describes the relationship between reactant concentration and isotope fractionation and is valid for a mixed-fluid sample.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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).

  9. 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.

  10. 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

  11. 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.

  12. Improved analysis of micro- and nanomole-scale sulfur multi-isotope compositions by gas source isotope ratio mass spectrometry.

    PubMed

    Au Yang, David; Landais, Guillaume; Assayag, Nelly; Widory, David; Cartigny, Pierre

    2016-04-15

    Multiple sulfur isotope compositions are usually measured on relatively large samples (in the range of micromoles); however, sometimes only small amounts are available and thus it is necessary to analyze small (sub-micromole) samples. We report an improved method to measure multiple sulfur isotope compositions: δ(33) S, δ(34) S and δ(36) S values on the SF6 molecule (m/z 127, 128, 129, 131) for quantities down to 0.1 micromole, and δ(33) S and δ(34) S values for quantities down to 20 nanomoles. Multiple sulfur isotope analyses including fluorination and purification of two international Ag2 S standards, IAEA-S1 and IAEA-S3, were carried out at various low concentrations on a dual-inlet isotope ratio mass spectrometer using a microvolume and modified resistor capacities. The analyses yielded a narrow range of δ(34) S values vs CDT (the international standard), with an overall standard deviation of ±0.2 ‰, which was within the range of certified values. This demonstrates the feasibility of determining both Δ(33) S and Δ(36) S values on the sub-micromole scale, and Δ(33) S values on the nanomole scale with similar accuracy to conventional dual-inlet analyses. The analysis of the three S-isotope ratios on the SF6 molecule using the so-called conventional fluorination method and dual-inlet ion ratio mass spectrometry is reliable for sample sizes down to ~20 nanomoles. Despite being close to the theoretical limits for maintaining the viscous flow regime of gas in the capillary, errors were not limited by counting statistics, but probably relate to sample gas purification. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  13. 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

  14. Determination of the geographical origin of Chinese teas based on stable carbon and nitrogen isotope ratios*

    PubMed Central

    Zhang, Long; Pan, Jia-rong; Zhu, Cheng

    2012-01-01

    The objective of this study was to investigate the geographical origin of Chinese teas using carbon and nitrogen stable isotope ratio technology. The results showed that inter-provincial dispersion of teas in Guangdong (GD), Guangxi (GX), Hainan (HA), Fujian (FJ), Shandong (SD), Sichuan (SC), Chongqing (CQ), and Henan (HN) provinces was high, while in Zhejiang (ZJ), Hubei (HB), Yunnan (YN), and Anhui (AH) provinces, it was low. Tea samples from GD, GX, HA, and FJ provinces were clustered in one group and separated from those from AH and HB provinces. Thus, carbon and nitrogen stable isotope ratio technology could discriminate teas from among some provinces of China, but not from among others. Better separation might be obtained with a combination of isotopic ratios and other indexes, such as elemental data and organic components. PMID:23024049

  15. 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.

  16. Boron and Lithium Isotope Determinations in Minerals from Subduction-Related Rocks by LA-MC-ICPMS

    NASA Astrophysics Data System (ADS)

    Martin, C.; Harlow, G. E.; Ponzevera, E.; Marschall, H.

    2014-12-01

    Lithium (Li) and boron (B) are incompatible light elements that preferentially partition into the fluid phase, whether melt or aqueous liquid, and thus are useful for tracking fluid-related processes in rocks. Currently, most of the Li isotopic data available on subduction-related rocks are whole-rock analysis; and the few B isotopic analyses on subduction material have been carried out on whole-rock or in-situ in accessory phase (tourmaline). The new method presented here couples an ESI New Wave UP-193-FX ArF* (193 nm) excimer laser ablation microscope with a Neptune Plus (Thermo Scientific) MC-ICP-MS. In situ B and Li isotopic analyses were carried out on mica and pyroxenes from jadeitites and albite mica-rocks from a subduction-related mélange. These results have been compared with SIMS analyses for B on the same mineral samples and with MC-ICP-MS analyses for Li on whole-rock or a mineral separate from the same sample. The results show that for B concentrations above 15 μg/g, the data obtained by LA-MC-ICPMS and by SIMS are similar within error, for both mica and pyroxene. The significant improvement of LA-MC-ICPMS compared to SIMS is the duration of measurements: one analysis takes 3 minutes by LA-MC-ICPMS, and 32 minutes by SIMS. Such a method therefore permits multiplying the number of isotopic analyses, providing a better interpretation of the studied samples, with a lateral resolution and an error on each measurement similar to those obtained with SIMS. The results show that for Li concentrations above 10μg/g, the data obtained by LA-MC-ICPMS and by MC-ICP-MS are also similar within error, for both mica and pyroxene. The significant improvement of LA-MC-ICPMS compared to MC-ICP-MS is better spatial resolution. Indeed, many of the mineral phases encountered in subduction-related rocks display a strong chemical zoning, and the analyses carried out by wet chemistry and MC-ICP-MS average the isotopic values of the different zones. This newly developed

  17. 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.

    2017-03-01

    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

  18. 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.

  19. Isotope ratios of lead in Japanese women's hair of the twentieth century.

    PubMed

    Matsumoto, Megumi; Yoshinaga, Jun

    2010-03-01

    Isotope ratios of lead ((207)Pb/(206)Pb and (208)Pb/(206)Pb) in Japanese women's hair of the twentieth century were measured to evaluate lead contamination of human proximate environment of those days. The historic hair samples (n = 40) were collected in 1980s by staffs of Department of Human Ecology, University of Tokyo, from Japanese women who cut their hair in 1910s to 1968 by themselves for hair piece or needle pad and who had stored it by the time of collection. Additional five contemporary hair samples (one from male and four from females) were also included. The hair samples were digested with HNO(3), diluted with water to Pb concentration of 10 microg/kg, and isotope ratios were measured by inductively coupled plasma mass spectrometry. Isotope ratios as well as Pb concentration in the hair samples of the twentieth century varied to a considerable extent depending on the period of hair cut. The oldest hair samples (1910-1920s) had the highest concentration and the most distinct isotope ratios from those of Japanese domestic Pb indicating serious contamination of proximate environment of people of those days with Pb originated from mines in other regions of the world, probably through the usage of Pb-containing face powder. The concentration and isotope ratios of Pb decreased thereafter indicating less serious contamination of proximate environment of Japanese which, in turn, should have affected by environmental contamination of mid-twentieth century due to industrial activities and leaded gasoline. Contemporary Pb level was quite low (<1 mg/kg); however, isotope ratios were close to those in 1960s when hair concentration was assumed to be strongly affected by leaded gasoline.

  20. 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

  1. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    NASA Astrophysics Data System (ADS)

    Dishon, G.; Fisch, J.; Horn, I.; Kaczmarek, K.; Bijma, J.; Gruber, D. F.; Nir, O.; Popovich, Y.; Tchernov, D.

    2015-06-01

    Coral reefs occupy only ~0.1% of the oceans habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced significant global declines due to a variety of causes, one of the major being widespread coral bleaching events. During bleaching the coral expels its symbiotic algae losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) to demonstrate a distinct biologically-induced decline of boron (B) isotopic composition (δ11B) as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published δ11B data and our recorded "vital effect" of coral bleaching on the δ11B signal, we also describe at least two possible coral bleaching events since the Last Glacial Maximum. The implementation of this bleaching proxy holds the potential of identifying occurrences of coral bleaching throughout the geological record. A deeper temporal view of coral bleaching will enable scientists to determine if it occurred in the past during times of environmental change and what outcome it may have had on coral population structure.

  2. 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.

  3. Evaluation strategies for isotope ratio measurements of single particles by LA-MC-ICPMS.

    PubMed

    Kappel, S; Boulyga, S F; Dorta, L; Günther, D; Hattendorf, B; Koffler, D; Laaha, G; Leisch, F; Prohaska, T

    2013-03-01

    Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multi-collector-inductively coupled plasma mass spectrometry (MC-ICPMS) coupled to, for example, laser ablation (LA). In the present study, the applicability of different data evaluation strategies (i.e. 'point-by-point', 'integration' and 'linear regression slope' method) for the computation of (235)U/(238)U isotope ratios measured in single particles by LA-MC-ICPMS was investigated. The analyzed uranium oxide particles (i.e. 9073-01-B, CRM U010 and NUSIMEP-7 test samples), having sizes down to the sub-micrometre range, are certified with respect to their (235)U/(238)U isotopic signature, which enabled evaluation of the applied strategies with respect to precision and accuracy. The different strategies were also compared with respect to their expanded uncertainties. Even though the 'point-by-point' method proved to be superior, the other methods are advantageous, as they take weighted signal intensities into account. For the first time, the use of a 'finite mixture model' is presented for the determination of an unknown number of different U isotopic compositions of single particles present on the same planchet. The model uses an algorithm that determines the number of isotopic signatures by attributing individual data points to computed clusters. The (235)U/(238)U isotope ratios are then determined by means of the slopes of linear regressions estimated for each cluster. The model was successfully applied for the accurate determination of different (235)U/(238)U isotope ratios of particles deposited on the NUSIMEP-7 test samples.

  4. Boron isotope systematics during magma-carbonate interaction: an experimental study from Merapi (Indonesia) and Vesuvius (Italy)

    NASA Astrophysics Data System (ADS)

    Deegan, F. M.; Jolis, E. M.; Troll, V. R.; Freda, C.; Whitehouse, M.

    2011-12-01

    Carbonate assimilation is increasingly recognized as an important process affecting the compositional evolution of magma and its inherent ability to erupt explosively due to release of carbonate-derived CO2 [e.g., 1, 2, 3]. In order to gain insights into this process, we performed short time-scale carbonate dissolution experiments in silicate melt using natural starting materials from Merapi and Vesuvius volcanoes at magmatic pressure and temperature [2, 4]. The experiments enable us to resolve in detail the timescales, textures and chemical features of carbonate assimilation. Three compositionally distinct glass domains have been defined: i) Ca-normal glass, similar in composition to the starting material; ii) Ca-rich, contaminated glass; and iii) a diffusional glass interface between the Ca-normal and Ca-rich glass, characterized by steady interchange between SiO2 and CaO. Here we present new boron isotope data for the experimental products obtained by SIMS. The glasses show distinct and systematic variation in their δ11B (%) values. The contaminated glasses generally show extremely negative δ11B values (down to -41 %) relative to both the uncontaminated experimental glass and fresh arc volcanics (-7 to +7 % [5]). Considering that carbonates have δ11B values of +9 to +26 [6], the data cannot be explained by simple mixing processes between the end-members alone. This implies that the δ11B of the original contaminant was drastically modified before being incorporated into the melt, which can be explained by B isotope fractionation during breakdown and degassing of the carbonate. Our data represents the first B isotope analyses of experimental products of carbonate assimilation. They provide novel and well constrained insights into the behavior of boron upon degassing of carbonate. This, in turn, has implications for both i) late stage contamination and volatile addition to hazardous volcanic systems located over carbonate basement (cf. [7]) and ii) studies of

  5. 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).

  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. Stable hydrogen and carbon isotope ratios of extractable hydrocarbons in the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, R. V.; Epstein, S.; Pizzarello, S.; Cronin, J. R.; Yuen, G. U.

    1991-01-01

    A fairly fool-proof method to ensure that the compounds isolated from meteorites are truly part of the meteorites and not an artifact introduced by exposure to the terrestrial environment, storage, or handling is presented. The stable carbon and hydrogen isotope ratios in several of the chemical compounds extracted from the Murchison meteorite were measured. The results obtained by studying the amino acids in this meteorite gave very unusual hydrogen and carbon isotope ratios. The technique was extended to the different classes of hydrocarbons and the hydrocarbons were isolated using a variety of separation techniques. The results and methods used in this investigation are described in this two page paper.

  8. 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

  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. Mechanistic studies of sesquiterpene cyclases based on their carbon isotope ratios at natural abundance.

    PubMed

    Tan, Wenhua; Bartram, Stefan; Boland, Wilhelm

    2017-01-03

    During the process of terpene biosynthesis, C-C bond breaking and forming steps are subjected to kinetic carbon isotope effects, leading to distinct carbon isotopic signatures of the products. Accordingly, carbon isotopic signatures could be used to reveal the 'biosynthetic history' of the produced terpenoids. Five known sesquiterpene cyclases, regulating three different pathways, representing simple to complex biosynthetic sequences, were heterologously expressed and used for in vitro assays with farnesyl diphosphate as substrate. Compound specific isotope ratio mass spectrometry measurements of the enzyme substrate farnesyl diphosphate (FDP) and the products of all the five cyclases were performed. The calculated δ(13) C value for FDP, based on δ(13) C values and relative amounts of the products, was identical with its measured δ(13) C value, confirming the reliability of the approach and the precision of measurements. The different carbon isotope ratios of the products reflect the complexity of their structure and are correlated with the frequency of carbon-carbon bond forming and breaking steps on their individual biosynthetic pathways. Thus, the analysis of carbon isotopic signatures of terpenes at natural abundance can be used as a powerful tool in elucidation of associated biosynthetic mechanisms of terpene synthases and in future in vivo studies even without 'touching' the plant. © 2017 John Wiley & Sons Ltd.

  11. 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.

  12. Absolute Isotopic Abundance Ratios and the Accuracy of Δ47 Measurements

    NASA Astrophysics Data System (ADS)

    Daeron, M.; Blamart, D.; Peral, M.; Affek, H. P.

    2016-12-01

    Conversion from raw IRMS data to clumped isotope anomalies in CO2 (Δ47) relies on four external parameters: the (13C/12C) ratio of VPDB, the (17O/16O) and (18O/16O) ratios of VSMOW (or VPDB-CO2), and the slope of the triple oxygen isotope line (λ). Here we investigate the influence that these isotopic parameters exert on measured Δ47 values, using real-world data corresponding to 7 months of measurements; simulations based on randomly generated data; precise comparisons between water-equilibrated CO2 samples and between carbonate standards believed to share quasi-identical Δ47 values; reprocessing of two carbonate calibration data sets with different slopes of Δ47 versus T. Using different sets of isotopic parameters generally produces systematic offsets as large as 0.04 ‰ in final Δ47 values. What's more, even using a single set of isotopic parameters can produce intra- and inter-laboratory discrepancies in final Δ47 values, if some of these parameters are inaccurate. Depending on the isotopic compositions of the standards used for conversion to "absolute" values, these errors should correlate strongly with either δ13C or δ18O, or more weakly with both. Based on measurements of samples expected to display identical Δ47 values, such as 25°C water-equilibrated CO2 with different carbon and oxygen isotope compositions, or high-temperature standards ETH-1 and ETH-2, we conclude that the isotopic parameters used so far in most clumped isotope studies produces large, systematic errors controlled by the relative bulk isotopic compositions of samples and standards, which should be one of the key factors responsible for current inter-laboratory discrepancies. By contrast, the isotopic parameters of Brand et al. [2010] appear to yield accurate Δ47 values regardless of bulk isotopic composition. References:Brand, Assonov and Coplen [2010] http://dx.doi.org/10.1351/PAC-REP-09-01-05

  13. 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

  14. 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.

  15. 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

  16. The CN/C15N isotopic ratio towards dark clouds

    NASA Astrophysics Data System (ADS)

    Hily-Blant, P.; Pineau des Forêts, G.; Faure, A.; Le Gal, R.; Padovani, M.

    2013-09-01

    Understanding the origin of the composition of solar system cosmomaterials is a central question, not only in the cosmochemistry and astrochemistry fields, and requires various approaches to be combined. Measurements of isotopic ratios in cometary materials provide strong constraints on the content of the protosolar nebula. Their relation with the composition of the parental dark clouds is, however, still very elusive. In this paper, we bring new constraints based on the isotopic composition of nitrogen in dark clouds, with the aim of understanding the chemical processes that are responsible for the observed isotopic ratios. We have observed and detected the fundamental rotational transition of C15N towards two starless dark clouds, L1544 and L1498. We were able to derive the column density ratio of C15N over 13CN towards the same clouds and obtain the CN/C15N isotopic ratios, which were found to be 500 ± 75 for both L1544 and L1498. These values are therefore marginally consistent with the protosolar value of 441. Moreover, this ratio is larger than the isotopic ratio of nitrogen measured in HCN. In addition, we present model calculations of the chemical fractionation of nitrogen in dark clouds, which make it possible to understand how CN can be deprived of 15N and HCN can simultaneously be enriched in heavy nitrogen. The non-fractionation of N2H+, however, remains an open issue, and we propose some chemical way of alleviating the discrepancy between model predictions and the observed ratios. Appendices are available in electronic form at http://www.aanda.orgThe reduced spectra (in FITS format) are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/557/A65

  17. 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.

  18. 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.

  19. Deuterium stable isotope ratios as tracers of water resource use: an experimental test with rock doves.

    PubMed

    McKechnie, Andrew E; Wolf, Blair O; Martínez del Rio, Carlos

    2004-07-01

    Naturally-occurring deuterium stable isotope ratios can potentially be used to trace water resource use by animals, but estimating the contribution of isotopically distinct water sources requires the accurate prediction of isotopic discrimination factors between water inputs and an animal's body water pool. We examined the feasibility of using estimates of water fluxes between a bird and its environment with a mass-balance model for the deuterium stable isotope ratio of avian body water (deltaDbody) to predict isotopic discrimination factors. Apparent fractionation and thus discrimination factors were predicted to vary with the proportion of an animal's total water losses than could be attributed to evaporative processes. To test our ability to predict isotopic discrimination, we manipulated water intake and evaporative water loss in rock doves (Columba livia) by providing them with fresh water or 0.15 M NaCl solution in thermoneutral or hot environments. After we switched the birds from drinking water with deltaD=-95 per thousand VSMOW (Vienna Standard Mean Ocean Water) to enriched drinking water with deltaD=+52 per thousand VSMOW, steady-state deltaDbody was approached asymptotically. The equilibrium deltaDbody was enriched by 10-50 per thousand relative to water inputs. After isotopic equilibrium was reached, the degree of enrichment was positively related (r2=0.34) to the fraction of total water loss that occurred by evaporation (revap/rH2O)supporting the major prediction of the model. The variation we observed in discrimination factors suggests that the apparent fractionation of deuterium will be difficult to predict accurately under natural conditions. Our results show that accurate estimates of the contribution of different water sources to a bird's body water pool require large deuterium isotopic differences between the sources.

  20. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Intercolony variability of skeletal oxygen and carbon isotope ratios of corals: temperature-controlled tank experiment and field observation

    NASA Astrophysics Data System (ADS)

    Suzuki, A.; Omata, T.; Kawahata, H.

    2005-12-01

    We conducted tank experiments in which we grew Porites spp. colonies in thermostated seawater at five temperature settings under moderate light intensity. A skeletal isotope microprofiling technique applied along the major growth axis of each colony revealed that the oxygen isotope ratios of newly deposited skeleton in most colonies remained almost constant during tank incubation. However, the oxygen isotope ratios displayed a surprisingly large intercolony variability (~1‰ at each temperature setting) although the mean slope obtained for the temperature - skeletal oxygen isotope ratio relationship was close to previous results. The variations in the oxygen isotope ratios were apparently caused by kinetic isotope effects related to variations in the skeletal growth rate rather than by species-specific variability or genetic differences within species. Carbon isotope ratios showed significantly inverse correlation with linear growth rates, suggesting a kinetic isotope control at low growth rates. We also examined oxygen and carbon isotope ratios of Porites corals collected from coral reefs of southern Ryukyu Islands, Japan. In shallow faster-growing corals, oxygen and carbon isotope ratios showed out-of-phase annual fluctuations. In contrast, in deep slower growing corals (mean annual linear extension < 4.8 mm yr1), oxygen and carbon isotope fluctuations were in phase, which has been identified as a pattern influenced by kinetic isotope effects. The slower growing corals were strongly influenced, and the faster growing corals weakly influenced, by kinetic isotope effects over metabolic isotope effects. Growth-rate-related kinetic isotope effects found in both the cultured corals and the deep slower-growing corals may be, at least partly, attributed to low light condition.

  2. Boron nitride nanotube-mediated stimulation modulates F/G-actin ratio and mechanical properties of human dermal fibroblasts

    NASA Astrophysics Data System (ADS)

    Ricotti, Leonardo; das Neves, Ricardo Pires; Ciofani, Gianni; Canale, Claudio; Nitti, Simone; Mattoli, Virgilio; Mazzolai, Barbara; Ferreira, Lino; Menciassi, Arianna

    2014-02-01

    F/G-actin ratio modulation is known to have an important role in many cell functions and in the regulation of specific cell behaviors. Several attempts have been made in the latest decades to finely control actin production and polymerization, in order to promote certain cell responses. In this paper we demonstrate the possibility of modulating F/G-actin ratio and mechanical properties of normal human dermal fibroblasts by using boron nitride nanotubes dispersed in the culture medium and by stimulating them with ultrasound transducers. Increasing concentrations of nanotubes were tested with the cells, without any evidence of cytotoxicity up to 10 μg/ml concentration of nanoparticles. Cells treated with nanoparticles and ultrasound stimulation showed a significantly higher F/G-actin ratio in comparison with the controls, as well as a higher Young's modulus. Assessment of Cdc42 activity revealed that actin nucleation/polymerization pathways, involving Rho GTPases, are probably influenced by nanotube-mediated stimulation, but they do not play a primary role in the significant increase of F/G-actin ratio of treated cells, such effect being mainly due to actin overexpression.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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 Pu-240/Pu-239 ratios of 0.7 and 0.58 %, with precisions (95 % confidence intervals) of 1.49 and 0.91 %. The minor isotope Pu-238 was also quantified despite the presence of a significant quantity of U-238 in the samples.

  9. Locally Grown, Natural Ingredients? The Isotope Ratio Can Reveal a Lot!

    PubMed

    Rossier, Joël S; Maury, Valérie; Pfammatter, Elmar

    2016-01-01

    This communication gives an overview of selected isotope analyses applied to food authenticity assessment. Different isotope ratio detection technologies such as isotope ratio mass spectrometry (IRMS) and cavity ring down spectroscopy (CRDS) are briefly described. It will be explained how δ(18)O of water contained in fruits and vegetables can be used to assess their country of production. It will be explained why asparagus grown in Valais, in the centre of the Alps carries much less heavy water than asparagus grown closer to the sea coast. On the other hand, the use of δ(13)C can reveal whether a product is natural or adulterated. Applications including honey or sparkling wine adulteration detection will be briefly presented.

  10. Stable Cl And O Isotope Ratios Of Anthropogenic And Natural Perchlorates

    NASA Astrophysics Data System (ADS)

    Beloso, A.; Sturchio, N. C.; Böhlke, J.; Gu, B.; Horita, J.; Brown, G.; Hatzinger, P.

    2004-12-01

    Perchlorate (ClO4-) in aqueous systems, even in low concentrations, is recognized to have potential human health risks. The drinking and irrigation water supplies of millions of people in the U.S. have recently been found to be contaminated with perchlorate, and this problem continues to become even more widespread. Perchlorate, as a highly soluble and relatively inert anion, tends to persist over long time periods and its removal by conventional water treatment technologies is difficult and expensive. Many known sources of perchlorate contamination are anthropogenic, resulting from its extensive use as an oxidizer component in solid propellants for missiles, rockets, and fireworks. However, certain fertilizers derived from Chilean nitrate evaporate deposits are known to contain a low percentage of perchlorate (<0.5%) that may contaminate groundwater. New isotopic evidence provides insights on the possible natural sources of perchlorate in surface and ground waters. Stable isotope ratios of Cl and O can now be used to determine whether the source of perchlorates in a given area is natural or anthropogenic. Microbial perchlorate reduction has a large (˜15 per mil) kinetic isotope effect, and this may be used to identify whether natural attenuation of perchlorate is occurring. Anthropogenic perchlorate salts in milligram amounts are readily analyzed for 37Cl and 18O isotopes. Extracting an isotopically measurable amount of perchlorate from natural waters, which are usually within ppb range of concentrations, is a challenge. But with the use of a new class of highly-selective bifunctional anion exchange resins, recovery of trace amounts of perchlorate for accurate isotopic analysis has been demonstrated. Isotopic characterization is being conducted on anthropogenic perchlorate reagents, natural perchlorate-bearing salt deposits, and perchlorate-bearing groundwaters. Significant and consistent isotopic differences in both the Cl and O isotope ratios between

  11. Detecting shifts in tropical moisture imbalances with satellite-derived isotope ratios in water vapor

    NASA Astrophysics Data System (ADS)

    Bailey, A.; Blossey, P. N.; Noone, D.; Nusbaumer, J.; Wood, R.

    2017-06-01

    As global temperatures rise, regional differences in evaporation (E) and precipitation (P) are likely to become more disparate, causing the drier E-dominated regions of the tropics to become drier and the wetter P-dominated regions to become wetter. Models suggest that such intensification of the water cycle should already be taking place; however, quantitatively verifying these changes is complicated by inherent difficulties in measuring E and P with sufficient spatial coverage and resolution. This paper presents a new metric for tracking changes in regional moisture imbalances (e.g., E-P) by defining δDq—the isotope ratio normalized to a reference water vapor concentration of 4 mmol mol-1—and evaluates its efficacy using both remote sensing retrievals and climate model simulations in the tropics. By normalizing the isotope ratio with respect to water vapor concentration, δDq isolates the portion of isotopic variability most closely associated with shifts between E- and P-dominated regimes. Composite differences in δDq between cold and warm phases of El Niño-Southern Oscillation (ENSO) verify that δDq effectively tracks changes in the hydrological cycle when large-scale convective reorganization takes place. Simulated δDq also demonstrates sensitivity to shorter-term variability in E-P at most tropical locations. Since the isotopic signal of E-P in free tropospheric water vapor transfers to the isotope ratios of precipitation, multidecadal observations of both water vapor and precipitation isotope ratios should provide key evidence of changes in regional moisture imbalances now and in the future.

  12. Effects of caloric restriction on nitrogen and carbon stable isotope ratios in adult rat bone.

    PubMed

    Robertson, Kimberly L; Rowland, Neil E; Krigbaum, John

    2014-10-15

    Stable isotope analysis is a valuable technique for dietary estimation in ecological and archaeological research, yet many variables can potentially affect tissue stable isotope signatures. Controlled feeding studies across a range of species have consistently demonstrated impacts of caloric restriction on tissue stable isotope ratios, but most have focused on juvenile, fasting, and/or starving individuals, and most have utilized soft tissues despite the importance of bone for paleodietary analyses. The goal of this study was to determine whether temporally defined, moderate food restriction could affect stable carbon and/or nitrogen isotope ratios in adult mammalian bone - a tissue that arguably reflects long-term dietary signals. Adult rats fed a standard laboratory diet were restricted to 45% of ad libitum intakes for 3 or 6 months. Relevant anatomical and physiological parameters were measured to confirm that the restriction protocol resulted in significant nutritional stress and to provide independent data to facilitate interpretation of stable isotope ratios. Femoral bone δ(13)Ccollagen, δ(15)Ncollagen, and δ(13)Capatite values were determined by isotope ratio mass spectrometry. Calorie-restricted animals exhibited a small, yet significant enrichment in (15)Ncollagen compared with control animals, reflecting protein-calorie stress. While the δ(13)Ccollagen values did not differ, the δ(13)Capatite values revealed less enrichment in (13)C than in controls, reflecting catabolism of body fat. Independent anatomical and physiological data from these same individuals support these interpretations. Results indicate that moderate caloric restriction does not appreciably undermine broad interpretations of dietary signals in adult mammalian bone. Significant variability among individuals or groups, however, is best explained by marked differences in energy intake over variable timescales. An inverse relationship between the δ(13)Capatite and δ(15)Ncollagen

  13. Nitrate input/output budget and nitrate isotope ratio in forest ecosystems.

    NASA Astrophysics Data System (ADS)

    Tobari, Y.; Koba, K.; Fukushima, K.; Tokuchi, N.; Tateno, R.; Ohte, N.; Suzuki, N.; Toyoda, S.; Yoshida, N.

    2006-12-01

    Recent years nitrogen input to forest has been increased by industrial development and increase use of fossil fuel, so elucidating the fate of nitrate added to forest ecosystems is quite important issue for revealing its potential of nitrogen-removing from environment, and better management of forests. Forest ecosystems in mountains region, typically in Japan, vary in many respects from Europe or United States, therefore, It is not possible to make the research result of Europe and America simply adjust to Japan as it is. In this study, measurement of nitrogen and oxygen isotopic ratios of nitrate give us integrated information of nitrate dynamics in Japanese forest ecosystems. There are cedar/ cypress plantations in Japan, about 40 percent of the total forest area is, need to maintain, therefore forest disturbance by human activity (e.g. clearcutting or thinning) is large proportion of total forest ecosystems. Forest disturbance is considered to affect nitrate discharge in many ways (Aber et al. 1998), and contribution of atmospheric nitrate to total nitrate discharge is dramatically increased after disturbance (e.g. forest decline by acid rain: Durka et al. 1994). In our study site with different application (logging) history, nitrate concentrations in streamwater showed clear trend. Atmospheric nitrate has high oxygen isotope ratio (over 10 per-mill vs. VSMOW), while its nitrogen isotopic ratio is about 0 per-mill vs. Atmosphere N2 and nitrate undergone denitrification in soil has high nitrogen isotope ratio (Kendall 1998). Nitrate discharge from forest ecosystems is mainly regulated by plant/microbe uptake, nitrification (NH4 toNO3) and denitrification (NO3 to N2). If clear cut of plantation affects the ratio of atmospheric versus microbial (nitrified) nitrate in streamwater, together with high concentrations in younger forest, we can assume several signal of isotopic ratios of nitrate with the hypothesis below; 1) Streamwater from young forests has high oxygen

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

    USDA-ARS?s Scientific Manuscript database

    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...

  15. 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.

  16. 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...

  17. 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.

  18. 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...

  19. 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...

  20. 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 ...

  1. 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 ...

  2. 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...

  3. PHYLOGENETIC AND ENVIRONMENTAL INFLUENCES ON NITROGEN STABLE ISOTOPE RATIOS IN SPOROCARPS OF ECTOMYCORRHIZAL FUNGI

    EPA Science Inventory

    It has been suggested that nitrogen stable isotope ratios (expressed as d15N) of fungus sporocarps, in conjunction with d15N data from other ecosystem compartments, can be used to elucidate key processes in forest N-cycling. Although results of previous studies generally support ...

  4. Influence of forest disturbance on stable nitrogen isotope ratios in soil and vegetation profiles

    Treesearch

    Jennifer D. Knoepp; Scott R. Taylor; Lindsay R. Boring; Chelcy F. Miniat

    2015-01-01

    Soil and plant stable nitrogen isotope ratios (15 N) are influenced by atmospheric nitrogen (N) inputs and processes that regulate organic matter (OM) transformation and N cycling. The resulting 15N patterns may be useful for discerning ecosystem differences in N cycling. We studied two ecosystems; longleaf pine wiregrass (...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. Isotopic-ratio mass spectrometers for the analysis of uranium hexafluoride

    SciTech Connect

    Sulfridge, C.; Jones, H.C.

    1981-05-06

    Descriptions, including photographs, are presented of the two isotopic-ratio mass spectrometers which have been developed for the analysis of uranium hexafluoride. The objectives were to have these spectrometers meet the sensitivity and precision requirements of development and improvement programs at uranium enrichment facilities, and for universal application to on-stream monitoring of UF/sub 4/ in enrichment facilities.

  11. 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

  12. 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...

  13. The isotopic composition of galactic cosmic-ray lithium, beryllium, and boron

    NASA Technical Reports Server (NTRS)

    Garcia-Munoz, M.; Mason, G. M.; Simpson, J. A.

    1975-01-01

    The isotopes of cosmic-ray Li, Be, and B near 100 MeV per nucleon have been measured with cosmic-ray telescopes on board the IMP-7 and IMP-8 satellites during 1973 and 1974. The measured isotopic abundances provide a stringent test for models of interstellar propagation and solar modulation. It is found that the isotopic abundances can be explained using a steady-state interstellar propagation model with a 5-g/sq cm leakage mean free path. These results, taken along with Be-10 abundance measurements, indicate a longer lifetime for cosmic rays than that predicted by the usual assumption of an average interstellar density of 1 to 3 atoms per cu cm.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Boron isotopic composition of olivine-hosted melt inclusions from Gorgona komatiites, Colombia: New evidence supporting wet komatiite origin

    NASA Astrophysics Data System (ADS)

    Gurenko, Andrey A.; Kamenetsky, Vadim S.

    2011-12-01

    A fundamental question in the genesis of komatiites is whether these rocks originate from partial melting of dry and hot mantle, 400-500 °C hotter than typical sources of MORB and OIB magmas, or if they were produced by hydrous melting of the source at much lower temperatures, similar or only moderately higher than those known today. Gorgona Island, Colombia, is a unique place where Phanerozoic komatiites occur and whose origin is directly connected to the formation of the Caribbean Large Igneous Province. The genesis of Gorgona komatiites remains controversial, mostly because of the uncertain origin of volatile components which they appear to contain. These volatiles could equally result from shallow level magma contamination, melting of a "damp" mantle or fluid-induced partial melting of the source due to devolatilization of the ancient subducting plate. We have analyzed boron isotopes of olivine-hosted melt inclusions from the Gorgona komatiites. These inclusions are characterized by relatively high contents of volatile components and boron (0.2-1.0 wt.% H 2O, 0.05-0.08 wt.% S, 0.02-0.03 wt.% Cl, 0.6-2.0 μg/g B), displaying positive anomalies in the overall depleted, primitive mantle (PM) normalized trace element and REE spectra ([La/Sm] n = 0.16-0.35; [H 2O/Nb] n = 8-44; [Cl/Nb] n = 27-68; [B/Nb] n = 9-30, assuming 300 μg/g H 2O, 8 μg/g Cl and 0.1 μg/g B in PM; Kamenetsky et al., 2010. Composition and temperature of komatiite melts from Gorgona Island constrained from olivine-hosted melt inclusions. Geology 38, 1003-1006). The inclusions range in δ11B values from - 11.5 to + 15.6 ± 2.2‰ (1 SE), forming two distinct trends in a δ11B vs. B-concentration diagram. Direct assimilation of seawater, seawater-derived components, altered oceanic crust or marine sediments by ascending komatiite magma cannot readily account for the volatile contents and B isotope variations. Alternatively, injection of < 3wt.% of a 11B enriched fluid to the mantle source could

  20. 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.

  1. Traceability of different apple varieties by multivariate analysis of isotope ratio mass spectrometry data.

    PubMed

    Mimmo, Tanja; Camin, Federica; Bontempo, Luana; Capici, Calogero; Tagliavini, Massimo; Cesco, Stefano; Scampicchio, Matteo

    2015-11-15

    The awareness of customers of the origin of foods has become an important issue. The growing demand for foods that are healthy, safe and of high quality has increased the need for traceability and clear labelling. Thus, this study investigates the capability of C and N stable isotope ratios to determine the geographical origin of several apple varieties grown in northern Italy. Four apple varieties (Cripps Pink, Gala, Golden Delicious, Granny Smith) have been sampled in orchards located in the Districts of Bolzano, Ferrara, Verona and Udine (northern Italy). Carbon (δ(13) C) and nitrogen (δ(15) N) isotope values of the whole apple fruits and three sub-fractions (peel, pulp and seed) have been determined simultaneously by isotope ratio mass spectrometry. The δ(13) C and δ(15) N values of apples and apple sub-fractions, such as peel, seed and pulp, were significantly affected by the geographical origin and the fruit variety. The four varieties could be distinguished to a certain extent only within each district. A 99% correct identification of the samples according to their origin was, however, achieved by cross validation with the 'leave-one-out' method. This study proves the potential of stable isotopes to discriminate the geographical origin of apples grown in orchards located only a few hundreds of kilometres apart. Stable isotopes were also able to discriminate different apple varieties, although only within small geographical areas. Copyright © 2015 John Wiley & Sons, Ltd.

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Argon, oxygen, and boron isotopic evidence documenting 40ArE accumulation in phengite during water-rich high-pressure subduction metasomatism of continental crust

    NASA Astrophysics Data System (ADS)

    Menold, Carrie A.; Grove, Marty; Sievers, Natalie E.; Manning, Craig E.; Yin, An; Young, Edward D.; Ziegler, Karen

    2016-07-01

    The Luliang Shan area of the North Qaidam high pressure (HP) to ultrahigh pressure (UHP) metamorphic terrane in northwestern China features thick, garnet- and phengite-rich metasomatic selvages that formed around gneiss-hosted mafic eclogite blocks during HP conditions. Here we present new 40Ar/39Ar, δ18 O, and δ11 B results from a previously studied 30 m, 18 sample traverse that extends from the host gneiss into a representative eclogite block. Previous thermobarometry and new mica-quartz oxygen isotope thermometry from the traverse reveal that the phengite-rich selvage formed at temperatures similar to those recorded by the eclogites at peak pressure. Quartz and white mica δ18 O data from the selvage cannot be explained by simple mixing of gneiss and eclogite, and indicate a fluid/rock ratio >1 during regional-scale infiltration of high δ18 O (ca. 14‰) fluids. Heavy δ18 O overgrowths of metamorphic zircon over lighter δ18 O detrital grains indicate that the gneiss was similarly affected. Starkly contrasting boron content and δ11 B compositions for the host gneiss and the selvage also cannot be explained by local-scale devolatilization of the gneiss to form the selvage. Instead, the boron systematics are best attributed to two distinct phases of fluid infiltration: (1) low-boron selvage phengite with δ11 B from -10 to -30‰ grew under HP conditions; and (2) tourmaline and boron-rich muscovite with generally positive δ11 B crystallized in the host gneiss under subsequent lower pressure epidote-amphibolite facies conditions as the Luliang Shan gneiss terrane was exhumed past shallower portions of the subduction channel. Consistent with observations made worldwide, we were able to identify uptake of excess argon (40ArE) in phengite as a high pressure phenomenon. Phengite 40Ar/39Ar ages from massive eclogite exceed the ca. 490 Ma zircon U-Pb age of eclogite metamorphism by a factor of 1.5. However, phengite ages from the more permeable schistose selvage

  8. 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.

  9. 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.

  10. Improving precision in resonance ionization mass spectrometry : influence of laser bandwidth in uranium isotope ratio measurements.

    SciTech Connect

    Isselhardt, B. H.; Savina, M. R.; Knight, K. B.; Pellin, M. J.; Hutcheon, I. D.; Prussin, S. G.

    2011-03-01

    The use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of {sup 235}U/{sup 238}U ratios by resonance ionization mass spectrometry (RIMS) to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a three-color, three-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.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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%).

  16. Determination of the Galaxy age by the method of uranium-thorium-plutonium isotopic ratios

    NASA Astrophysics Data System (ADS)

    Panov, I. V.; Lutostansky, Yu. S.; Eichler, M.; Thielemann, F.-K.

    2017-07-01

    The dependence of the Galaxy age ( T G), as determined by the method of uranium-thorium isotopic ratios, on the parameters of the nucleosynthesis model is studied within the theory of galactic nucleosynthesis. It is shown that TG depends strongly both on the scenario of the production of nuclei in the r-process and those features of neutron-rich nuclei that are used in the respective analysis and on galactic-nucleosynthesis parameters. The effect of a sudden nucleosynthesis spike before the formation of a solar system on the Galaxy age is evaluated. The region of admissible values of the parameters of galacticnucleosynthesis theory is discussed. The method of uranium-thorium isotopic ratios is supplemented with the 244Pu/238U ratio for yet another cosmochronometer pair, and the Galaxy age is estimated on the basis of the model modified in this way.

  17. 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.

  18. Measurement of oxygen isotope ratios ((18)O/(16)O) of aqueous O2 in small samples by gas chromatography/isotope ratio mass spectrometry.

    PubMed

    Pati, Sarah G; Bolotin, Jakov; Brennwald, Matthias S; Kohler, Hans-Peter E; Werner, Roland A; Hofstetter, Thomas B

    2016-03-30

    Oxygen isotope fractionation of molecular O2 is an important process for the study of aerobic metabolism, photosynthesis, and formation of reactive oxygen species. The latter is of particular interest for investigating the mechanism of enzyme-catalyzed reactions, such as the oxygenation of organic pollutants, which is an important detoxification mechanism. We developed a simple method to measure the δ(18) O values of dissolved O2 in small samples using automated split injection for gas chromatography coupled to isotope ratio mass spectrometry (GC/IRMS). After creating a N2 headspace, the dissolved O2 partitions from aqueous solution to the headspace, from which it can be injected into the gas chromatograph. In aqueous samples of 10 mL and in diluted air samples, we quantified the δ(18) O values at O2 concentrations of 16 μM and 86 μM, respectively. The chromatographic separation of O2 and N2 with a molecular sieve column made it possible to use N2 as the headspace gas for the extraction of dissolved O2 from water. We were therefore able to apply a rigorous δ(18) O blank correction for the quantification of (18) O/(16) O ratios in 20 nmol of injected O2 . The successful quantification of (18) O-kinetic isotope effects associated with enzymatic and chemical reduction of dissolved O2 illustrates how the proposed method can be applied for studying enzymatic O2 activation mechanisms in a variety of (bio)chemical processes. Copyright © 2016 John Wiley & Sons, Ltd.

  19. 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

  20. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    NASA Astrophysics Data System (ADS)

    Dishon, G.; Fisch, J.; Horn, I.; Kaczmarek, K.; Bijma, J.; Gruber, D. F.; Nir, O.; Popovich, Y.; Tchernov, D.

    2015-10-01

    Coral reefs occupy only ~ 0.1 percent of the ocean's habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced a significant global decline due to a variety of causes, one of the major causes being widespread coral bleaching events. During bleaching, the coral expels its symbiotic algae, thereby losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) to demonstrate a distinct biologically induced decline of boron (B) isotopic composition (δ11B) as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published δ11B data and our recorded vital effect of coral bleaching on the δ11B signal, we also des