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Sample records for 18o 24mg 44ca

  1. Isospin mixing in 24Mg

    International Nuclear Information System (INIS)

    We have used the #betta#-#betta# circular polarization (CP) correlation technique to measure the isospin-forbidden Fermi matrix element for the #betta#+ decay of 24Al to the 4+ T=1 state in 24Mg at E/sub x/=8.437 MeV. The 24Al activity was produced by bombarding a natural Mg target with 18 MeV protons. The #betta#-#betta# CP correlation was measured using a novel apparatus which featured good energy resolution in both the #betta# and #betta# arms. The CP sensitive #betta#-ray detector utilized a transmission-mode Compton polarimeter and a 12.7 cm x 15.2 cm NaI detector. The #betta# detector was a telescope with a 700 μm surface barrier detector and a 5.1 cm x 12.7 cm plastic scintillator. The #betta#-#betta# CP asymmetry A [defined by W(theta, t tilde) = 1 + t tilde v/c A tilde cos theta where t tilde is the photon helicity] was found to be A tilde = -0.145 +- 0.030. After applying a correction for feeding of the 8.437 MeV state from the analog state this value of A tilde corresponds to a charge dependent matrix element between the 9.5 MeV 4+T=1 and 8.4 MeV T=O levels of [+;O[H/sub CD/]4+;1>] = 106 +- 40 keV which is the largest matrix element of H/sub CD/ ever observed in #betta# decay. For comparison the charge dependent matrix element between the 9.5 MeV state and the 4.1 MeV 4+ state, previously measured in 24Na decays is only 5.4 +- 2.2 keV. Our exceptionally large value occurs because the 9.5 MeV T=1 and 8.4 MeV T=O states have very similar space and spin wavefunctions. This matrix element is consistent with predictions which ascribe the entire effect to Coulomb forces

  2. Clustering effects in 48Cr composite nuclei produced via the 24Mg+24Mg reaction

    Science.gov (United States)

    Di Nitto, A.; Vardaci, E.; Brondi, A.; La Rana, G.; Cinausero, M.; Gelli, N.; Moro, R.; Nadtochy, P. N.; Prete, G.; Vanzanella, A.

    2016-04-01

    The nuclear properties of 48Cr composite α -like nuclei produced at 60 MeV of excitation energy via the 24Mg+24Mg reaction were investigated. This excitation energy corresponds to a resonance with a narrow width (170 keV) observed in the elastic and inelastic channels, which was interpreted as a highly deformed state. To gain insight on the deformation of this state exclusive measurements of light charged particles were carried out with 8 π LP apparatus at Laboratori Nazionali di Legnaro and compared to statistical model predictions. The measured of α -particle energy spectra, α -evaporation residues, α -α , and α -α -α correlations indicate the limitation of the rotating liquid drop model in describing the nuclear shape of the compound nucleus along the decay cascade. To reproduce the full set of experimental data very elongated nuclear shapes had to be considered, with an axis ratio 3 :1 at the resonance angular momentum. This large deformation is consistent with previous findings for α -like nuclei and with the predictions of the cranked cluster model.

  3. Flashing coherently rotating carbon sticks in $^{24}$Mg+$^{24}$Mg collision

    CERN Document Server

    Zhao, M H; Merlo, O; Huang, M R; Li, Y; Wang, J S

    2013-01-01

    We analyze quasi-periodic oscillations in the angle-averaged ($\\Delta\\theta_{cm}\\simeq 90^\\circ\\pm 25^\\circ $)excitation functions for the $^{24}Mg+^{24}Mg$ elastic-inelastic scattering and $\\alpha$-transfer channels on the energy interval $E_{cm}=44.86-47.76$ MeV.The period of the energy structures, $\\simeq$0.81 MeV, is interpreted as inverse half-period ($\\simeq 5\\times 10^{-21}$ sec.) of coherent rotation of highly excited short-lived ($\\simeq 3.6\\times 10^{-21}$ sec.) chain of a length $\\simeq 30$ fm. The rotational wave packet coherence survives (i) the energy relaxation (fully mixing ergodic dynamics) for the strongly overlapping states with fixed total spins and (ii) the strong distortion of the motion upon a change of the total spin.The present discussion leads us to the question: Is rotational coherence of large molecules necessarily destroyed in the conventionally statistical limit of structureless (non-selective) continuum under the conditions of complete intramolecular energy redistribution and vi...

  4. 16O+8Be cluster structure in 24Mg

    International Nuclear Information System (INIS)

    16O + 8Be cluster structure in 24Mg has been identified by observing the breakup into ground state 160 and 8Be fragments following inelastic scattering of 24Mg projectiles. The spectrum of states observed is compared to that previously measured in the 12C + 12C breakup channel to obtain information on the partial decay widths. (author)

  5. Preparation of 24Mg-Fe-Cu Target

    Institute of Scientific and Technical Information of China (English)

    FAN; Qi-wen; DU; Ying-hui; ZHANG; Rong

    2012-01-01

    <正>The three-layer-sandwich targets of 24Mg-Fe-Cu needed to be prepared in the physics experiment. The middle layers are thin ferromagnetic Fe layers of about 3.2 mg/cm2. The recoil stopper layers are thick crystallized and defect-free Cu layers of about 15 mg/cm2. The thickness of the 24Mg target layers is about 300 μg/cm2, and the uniformity should be better than 90%.

  6. Molecular resonances and the Jacobi shape transition: the case of 24Mg+24Mg and 48Cr

    International Nuclear Information System (INIS)

    A fast rotating 48Cr is predicted to be highly prolate and deformed after a Jacobi shape transition and just before fission. In this article, it is proposed that an arrow and high spin 24Mg+24Mg resonance corresponds to the formation of this exotic 48Cr. Moreover the 24Mg+24Mg reaction has been studied at the Legnaro Tandem at a CM bombarding energy of 45.7 MeV, where a narrow and high spin resonance has been reported previously. To establish the connection between the resonance and a molecular state of 48Cr, the decay of the resonance into the inelastic and fusion-evaporation channels has been investigated. The ON and OFF resonance decay yields have been measured using, for the inelastic channels, the fragment spectrometer PRISMA and the gamma array CLARA, and, for the fusion-evaporation channels, the Si array EUCLIDES and the gamma array GASP. Strong resonant effects have been observed in the inelastic channels involving the 2+ and 4+ states of the 24Mg ground state (g.s.) band. Weaker effects are also seen in certain fusion-evaporation channels. Both results will be discussed here. (authors)

  7. Alpha-particle decays from excited states in 24Mg

    Institute of Scientific and Technical Information of China (English)

    LIOTTA; R; J

    2011-01-01

    Using a cluster model based on the Woods-Saxon potential, alpha-particle decays from excited states in 24Mg have been system atically investigated. Calculations can in general reproduce experimental data, noticing the fact that the preformation factor P of alpha particle in alpha-decaying nuclei is of order from 100 to 10?2. This can be the evidence for the α+20Ne structure in 24Mg. Meanwhile, the results also show the existence of other configurations, such as 16O+2α. Since the calculated decay widths are very sensitive to the angular momentum carried by the outgoing cluster (α particle), our results could serve as a guide to experimental spin assignments.

  8. Neutron inelastic cross section measurements for 24Mg

    OpenAIRE

    OLACEL A.; Borcea, C.; DESSAGNE Philippe; Kerveno, M.; NEGRET A.; PLOMPEN Arjan

    2014-01-01

    The gamma production cross sections from the neutron inelastic scattering on 24Mg were measured for neutron energies up to 18 MeV at GELINA (Geel Linear Accelerator), the neutron source operated by EC-JRC-IRMM, Belgium. The level cross section and the total inelastic cross section were determined. We used the GAINS (Gamma Array for Inelastic Neutron Scattering) spectrometer with 7 large volume HPGe detectors placed at 110◦ and 150◦ with respect to the beam direction. The neutron flux was dete...

  9. $^{24}$Mg($p$, $\\alpha$)$^{21}$Na reaction study for spectroscopy of $^{21}$Na

    CERN Document Server

    Cha, S M; Kim, A; Lee, E J; Ahn, S; Bardayan, D W; Chipps, K A; Cizewski, J A; Howard, M E; Manning, B; O'Malley, P D; Ratkiewicz, A; Strauss, S; Kozub, R L; Matos, M; Pain, S D; Pittman, S T; Smith, M S; Peters, W A

    2015-01-01

    The $^{24}$Mg($p$, $\\alpha$)$^{21}$Na reaction was measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to better constrain spins and parities of energy levels in $^{21}$Na for the astrophysically important $^{17}$F($\\alpha, p$)$^{20}$Ne reaction rate calculation. 31 MeV proton beams from the 25-MV tandem accelerator and enriched $^{24}$Mg solid targets were used. Recoiling $^{4}$He particles from the $^{24}$Mg($p$, $\\alpha$)$^{21}$Na reaction were detected by a highly segmented silicon detector array which measured the yields of $^{4}$He particles over a range of angles simultaneously. A new level at 6661 $\\pm$ 5 keV was observed in the present work. The extracted angular distributions for the first four levels of $^{21}$Na and Distorted Wave Born Approximation (DWBA) calculations were compared to verify and extract angular momentum transfer.

  10. Reaction mechanism for the symmetric breakup of 24Mg following an interaction with 12C

    International Nuclear Information System (INIS)

    Data on the yield of the symmetric breakup of 24Mg as a function of beam energy are presented and compared with detailed calculations of the energy dependence. The 24Mg states seen in symmetric breakup agree with previously observed breakup states having spin and parities Jπ=4+,(6+),8+. The data allow the variations of yield for indivual states to be judged, as the beam energy is varied. The variation in the yield of the 4+ states is compared in detail with calculations assuming several possible compound nuclear or direct reaction mechanisms. It is concluded that a massive (12C) transfer or a simple statistical compound process are unlikely mechanisms, but that each of several other mechanisms is consistent with the data. ((orig.))

  11. Entrance channel dependence of back angle yields: orbiting in 24Mg+16O reaction

    International Nuclear Information System (INIS)

    The back-angle yields of the oxygen and carbon particles from the 24Mg+16O reaction have been measured at E/sub Lab/(24Mg) = 79.5 MeV by using reverse kinematics. Comparison with data for the 28Si+12C reaction forming the same compound nucleus at the same excitation energy and with very similar spin distribution, demonstrates a strong entrance channel effect which is favoring the break-up into the entrance channel with large excitation energy. This result qualitatively supports the picture of the formation of a long-lived orbiting complex whose structure and decay are dependent on the entrance channel. The compound nucleus contribution has been inferred to be less than 15% of the measured oxygen cross-section. 9 references

  12. A Study of 16O +24Mg Reaction Using a Coupled Channel Approach

    Institute of Scientific and Technical Information of China (English)

    A.A.Farra

    2003-01-01

    Different interpretations are introduced to describe the uprising oscillatory structures of 16O +24Mg re-action. The gross resonant structures to the ground- and first-excited states have been studied successfully in termsof both the DWBA and coupled channel calculations. The DWBA results introduce a reasonable description of theangular distributions and excitation function data. The coupled channel calculations provide a better agreement withthe experimental forward and backward angle data than the DWBA calculations.

  13. Study and realization of heavy ion detectors. Application to the reaction 12C+24Mg

    International Nuclear Information System (INIS)

    The present study deals with elastic and inelastic scattering of 24 to 44 MeV center of mass 24Mg ions by 12C. The Strasbourg Q3D magnetic spectrograph has been used to measure the 1800 c.m. scattering cross-sections in detecting the corresponding recoiling ions at THETAsub(Lab) = 00. Statistical fluctuations are probably present. The 1,5 m long position sensitive focal plan hybride counter is described

  14. Experimental study of the fast neutron scattering from 24Mg, 28Si and 32S

    International Nuclear Information System (INIS)

    Differential cross section measurements for neutron scattering from 24Mg, 28Si and 32S at 9.76 and 14.83 MeV incident neutron energies have been undertaken. The experimental technique is based on the time-of-flight method with a pulsed neutron beam. Scattered neutrons have been detected by a spectrometer composed of five detectors. Elastic and inelastic scattering cross sections for levels of up to 6 MeV excitation energy have been obtained for the angular range from 15 to 1600 in 50 steps. These measurements will be used in a coupled-channel analysis to extract potential and deformation parameters

  15. Clustering aspects in N = Z nucleus 24Mg studied by antisymmetized molecular dynamics

    International Nuclear Information System (INIS)

    Cluster structure of highly excited states of 24Mg has been investigated by the antisymmetrized molecular dynamics. Imposing the constraints on the expectation values of harmonic oscillator quanta, α+20Ne, 12C+12C and 6α cluster wave functions were generated without any a priori assumption. The isoscalar monopole excitation function is also calculated and reasonably agrees with the observation. It is found that α+20Ne, 12C+12C and 6α clusters appear as the prominent peaks in the strength function

  16. Study of the elastic scattering of {sup 32}S by {sup 24}Mg at low energies

    Energy Technology Data Exchange (ETDEWEB)

    Hassanain, Mahmoud A., E-mail: mho1959@yahoo.com [Department of Physics, King Khalid University, Abha (Saudi Arabia); Ibraheem, Awad A. [Department of Physics, King Khalid University Physics Department, Al-Azhar University (Egypt)

    2015-12-15

    The elastic scattering angular distribution of {sup 32}S on {sup 24}Mg at energies ranging from 65 to 110 MeV has been analyzed in the framework of the double folding (DF) model, using different effective nucleon-nucleon (NN) interactions based on the M3Y-Reid interaction. The Pauli correlation, zero-range, and finite-range exchange parts of the NN interactions are considered in the folding procedure to treat the single nucleon knock-on exchange term (SNKE) in the optical model. Successful reproduction of the data has been obtained with all the potentials considered in the present study. It is clear that the effect of Pauli correlation increases as the energy increases. Our calculations are insensitive to the strength of the imaginary potential used in the fit of the experimental data. We find also that the threshold anomaly is less pronounced in the {sup 32}S + {sup 24}Mg system. Our reaction cross sections are compared with the data, and the consistency between the real and imaginary volume integrals are checked by the dispersion relation. (author)

  17. An Analysis of the $^{12}$C+$^{24}$Mg Reaction Using A New Coupling Potential

    CERN Document Server

    Boztosun, I

    2001-01-01

    We introduce a new coupling potential to explain the experimental data for the $^{12}$C+$^{24}$Mg system at numerous energies in the laboratory system from 16.0 MeV to 24.0 MeV. This new coupled-channels based approach involves replacing the usual first derivative coupling potential by a new, second-derivative coupling potential. This paper first shows and discusses the limitation of the standard coupled-channels theory in the case where one of the nuclei in the reaction is strongly deformed. Then, this new approach is shown to improve consistently the agreement with the experimental data and has made major improvement on all the previous coupled-channels calculations for this system.

  18. Nuclear transparency and the onset of strong absorption regime in the 12C+24Mg system

    Science.gov (United States)

    Lichtenthäler, R.; Lépine-Szily, A.; Hussein, M. S.

    1999-10-01

    The elastic scattering of 12C+24Mg has been studied by means of a phase-shift analysis of 21 angular distributions ranging from Elab=16 MeV up to Elab=40 MeV. A tridimensional plot of the reflection coefficient of the S matrix as a function of the angular momentum and energy shows a well-defined region of energy, which separates two regimes: strong absorption for higher energies and the so-called ``anomalous transparency regime,'' recently observed in this system at low energies. The Argand diagrams of the S matrix in angular momentum space also present very contrasting behaviors in the two regions with very rapidly varying phases in the low energy region, which we associate with a parity dependent term in the S matrix directly related to significant coupling to the elastic transfer of a 12C nucleus.

  19. Nuclear transparency and the onset of strong absorption regime in the $^{12}C + ^{24}Mg$ system

    CERN Document Server

    Lichtenthäler, R; Hussein, M S

    1999-01-01

    The elastic scattering of 12C+24Mg has been studied by means of a phase-shift analysis of 21 angular distributions ranging from Elab=16MeV up to Elab=40MeV. A tri-dimensional plot of the reflection coefficient of the S-matrix as a function of the angular momentum and the energy shows a well defined region of energy which separates two regimes: strong absorption for higher energies and the so called "anomalous transparency regime", recently observed in this system at low energies. The Argand diagrams of the S-matrix in angular momentum space also present very contrasting behaviours in the two regions with very rapidly varying phases in the low energy region, which we associate with a parity dependent term in the S-matrix directly related to significant coupling to the elastic transfer of a 12C nucleus.

  20. Splitting of ISGMR strength in the light-mass nucleus $^{24}$Mg due to ground-state deformation

    CERN Document Server

    Gupta, Y K; Matta, J T; Patel, D; Peach, T; Hoffman, J; Yoshida, K; Itoh, M; Fujiwara, M; Hara, K; Hashimoto, H; Nakanishi, K; Yosoi, M; Sakaguchi, H; Terashima, S; Kishi, S; Murakami, T; Uchida, M; Yasuda, Y; Akimune, H; Kawabata, T; Harakeh, M N

    2015-01-01

    The isoscalar giant monopole resonance (ISGMR) strength distribution in $^{24}$Mg has been determined from background-free inelastic scattering of 386-MeV $\\alpha$ particles at extreme forward angles, including 0$^{\\circ}$. The ISGMR strength distribution has been observed for the first time to have a two-peak structure in a light-mass nucleus. This splitting of ISGMR strength is explained well by microscopic theory in terms of the prolate deformation of the ground state of $^{24}$Mg.

  1. Two-neutron transfer analysis of the 16O(18O,16O)18O reaction

    Science.gov (United States)

    Ermamatov, M. J.; Cappuzzello, F.; Lubian, J.; Cubero, M.; Agodi, C.; Carbone, D.; Cavallaro, M.; Ferreira, J. L.; Foti, A.; Garcia, V. N.; Gargano, A.; Lay, J. A.; Lenzi, S. M.; Linares, R.; Santagati, G.; Vitturi, A.

    2016-08-01

    Recently a quantitative description of the two-neutron transfer reaction 12C(18O,16O)14C was performed and the measured cross sections were successfully reproduced [M. Cavallaro et al., Phys. Rev. C 88, 054601 (2013), 10.1103/PhysRevC.88.054601]. This task was accomplished by combining nuclear structure calculations of spectroscopic amplitudes and a full quantum description of the reaction mechanism. Verification of such a theoretical approach to other heavy nuclear systems is mandatory in order to use (18O,16O ) reactions to assess pair configurations in nuclear states. In this work we apply this methodology to the 16O(18O,16O)18O reaction at 84 MeV. Experimental angular distributions for the two-neutron transfer to the ground state and 21+ state of 18O were obtained using the MAGNEX spectrometer at INFN-LNS. The roles of one- and two-step processes are analyzed under the exact finite range coupled reaction channel and the second order distorted wave Born approximation. We conclude that the one-step transfer mechanism is dominant in this system.

  2. Decay of the excited compound system {sup 48}Cr{sup *} formed through {sup 24}Mg + {sup 24}Mg, {sup 36}Ar + {sup 12}C and {sup 20}Ne + {sup 28}Si reactions

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh, K.P.; Subha, P.V.; Priyanka, B. [Kannur University, School of Pure and Applied Physics, Payyanur, Kerala (India)

    2016-05-15

    The total cross section, the intermediate mass fragment (IMF) production cross section, and the cross section for the formation of light particle (LP) for the decay of {sup 48}Cr{sup *} formed through the entrance channel {sup 24}Mg+{sup 24}Mg, have been evaluated using the barrier penetration model, taking the scattering potential as the sum of the Coulomb and nuclear proximity potential, for various E{sub CM} values. The computed results have been compared with the available experimental data of the total cross section corresponding to E{sub CM}=44.4 MeV for the entrance channel {sup 24}Mg+{sup 24}Mg, and were found to be in good agreement. The experimental values for the LP production cross section for the channel {sup 24}Mg+{sup 24}Mg were also seen to be agreeing with our calculations. Hence we have extended our studies and have thus computed the total cross section, IMF cross section and LP cross section for the decay of {sup 48}Cr{sup *} formed through the other two entrance channels {sup 36}Ar+{sup 12}C, and {sup 20}Ne+{sup 28}Si with different E{sub CM} values. It was found that the computed total cross sections for the entrance channel {sup 36}Ar+{sup 12}C with E{sub CM}=47 MeV agree well with the corresponding experimental values. Hence, we hope that our predictions on the evaluations of the IMF cross sections and the light charged particle cross sections for the decay of {sup 48}Cr{sup *}, formed through the two entrance channels {sup 36}Ar+{sup 12}C, and {sup 20}Ne+{sup 28}Si, can be used for further experimental studies. (orig.)

  3. Migration history of North Sea houting (Coregonus oxyrinchus L.) caught in Lake IJsselmeer (The Netherlands) inferred from scale transects of 88SR:44 Ca ratios

    NARCIS (Netherlands)

    Borcherding, J.; Pickhardt, C.; Winter, H.V.; Becker, J.S.

    2008-01-01

    North Sea houting, Coregonus oxyrinchus, became extinct in the River Rhine in the 1940 s and was reintroduced in the 1990 s. To study the migration history of individuals, the 88Sr:44Ca ratio of scales of 39 houting (10¿44 cm TL) caught in Lake IJsselmeer was analysed using laser ablation inductivel

  4. The intermediate energy elastic scattering of protons by α-cluster 20Ne and 24Mg nuclei

    International Nuclear Information System (INIS)

    The multiple diffraction scattering theory and the α-cluster model with dispersion have been applied for calculations of the observables for the elastic scattering of intermediate energy protons by 20Ne and 24Mg nuclei. The target nuclei are considered as composed of the core (16O nucleus) and additional α-clusters (one α-cluster for 20Ne nucleus and a dumb-bell α-cluster configuration for 24Mg nucleus). Taking into account the α-cluster configuration of the core, it was supposed that the additional α-cluster or center of mass of the dumb-bell are arranged with the most probability inside or outside of the core. The calculated observables for the elastic p–20Ne and p–24Mg scattering are in agreement with the existing experimental data. The influence of the deformed core contribution on the behavior of the calculated observables also is tested. (author)

  5. Production of neutral pions below the nucleon-nucleon threshold in the reactions 24Mg(16O,π0)X and 24Mg(4He,π0)X

    International Nuclear Information System (INIS)

    In the present thesis the production of neutral pions in the reaction 24Mg(16O,π0)X at 24 and 33 MeV/u as well as in the reaction 24Mg(4He,π0)X at a projectile energy of 43 MeV/u was studied by means of a lead-glass Cherenkov detector. The measured energy spectra can be well described by a parametrization by means of 1/E e sup(- E/E0) analogously to the bremsstrahlung model. The decrease parameters extracted from this indicate a stopping time in the order of magnitude of 10-24s, which confirms the assumption that the pions are produced in the early phase of the reaction before the onset of the equilibration of the fused system. (orig./HSI)

  6. Ion microscopic imaging of calcium transport in the intestinal tissue of vitamin D-deficient and vitamin D-replete chickens: A 44Ca stable isotope study

    International Nuclear Information System (INIS)

    The intestinal absorption of calcium includes at least three definable steps; transfer across the microvillar membrane, movement through the cytosolic compartment, and energy-dependent extrusion into the lamina propria, Tracing the movement of calcium through the epithelium has been hampered by lack of suitable techniques and, in this study, advantage was taken of ion microscopy in conjunction with cryosectioning and use of the stable isotope 44Ca to visualize calcium in transit during the absorptive process. The effect of vitamin D, required for optimal calcium absorption, was investigated. Twenty millimolar 44Ca was injected into the duodenal lumen in situ of vitamin D-deficient and vitamin D-replete chickens. At 2.5, 5.0, and 20.0 min after injection, duodenal tissue was obtained and processed for ion microscopic imaging. At 2.5 min. 44Ca was seen to be concentrated in the region subjacent to the microvillar membrane in tissue from both groups. At 5.0 and 20.0 min, a similar pattern of localization was evident in D-deficient tissues. In D-replete tissues, the distribution of 44Ca became more homogenous, indicating that vitamin D increased the rate of transfer of Ca2+ from the apical to the basolateral membrane, a function previously ascribed to the vitamin D-induced calcium-binding protein (28-kDa calbindin-D). Quantitative aspects of the calcium absorptive process were determined in parallel experiments with the radionuclide 47Ca. Complementary information on the localization of the naturally occurring isotopes of calcium (40Ca) and potassium (39K) is also described

  7. 18O enrichment in phosphorus pools extracted from soybean leaves.

    Science.gov (United States)

    Pfahler, Verena; Dürr-Auster, Thilo; Tamburini, Federica; Bernasconi, M Stefano; Frossard, Emmanuel

    2013-01-01

    The objective of this study was to investigate the isotopic composition of oxygen bound to phosphate (δ(18)O-PO(4)) in different phosphorus (P) pools in plant leaves. As a model plant we used soybean (Glycine max cv Toliman) grown in the presence of ample P in hydroponic cultures. The leaf blades were extracted with 0.3 M trichloroacetic acid (TCA) and with 10 M nitric acid. These extractions allowed measurement of the TCA-soluble reactive P (TCA P) that is rapidly cycled within the cell and the total leaf P. The difference between total leaf P and TCA P yielded the structural P which includes organic P compounds not extractable by TCA. P uptake and its translocation and transformation within the soybean plants lead to an (18)O enrichment of TCA P (δ(18)O-PO(4) between 16.9 and 27.5‰) and structural P (δ(18)O-PO(4) between 42.6 and 68.0 ‰) compared with 12.4‰ in the phosphate in the nutrient solution. δ(18)O values of phosphate extracted from soybean leaves grown under optimal conditions are greater than the δ(18)O-PO(4) values of the provided P source. Furthermore, the δ(18)O-PO(4) of TCA P seems to be controlled by the δ(18)O of leaf water and the activity of inorganic pyrophosphatase or other pyrophosphatases. PMID:23106517

  8. A comparison of spectroscopic models of low excitation 2+ states in 24Mg and 28Si using inelastic proton scattering

    International Nuclear Information System (INIS)

    Distorted Wave approximation analyses of the inelastic scattering of 49.5 MeV protons from 24Mg and 28Si are used to compare 2+ transition densities that were obtained from a standard shell model, deformed potential models and an SU(3) model of the low excitation spectroscopy of these nuclei. Analyzing power predictions do not reproduce the data adequately; the discrepancies indicating a deficiency in the transition mechanism prescription

  9. Galactic interstellar 18O/17O ratios - a radial gradient?

    CERN Document Server

    Wouterloot, J G A; Brand, J; Davis, G R

    2008-01-01

    (Abridged) Our aim is to determine 18O/17O abundance ratios across the entire Galaxy. These provide a measure of the amount of enrichment by high-mass versus intermediate-mass stars. Such ratios, derived from the C18O and C17O J=1-0 lines alone, may be affected by systematic errors. Therefore, the C18O and C17O (1-0), (2-1), and (3-2), as well as the 13CO (1-0) and (2-1) lines, were observed towards 18 prominent galactic targets (a total of 25 positions). The combined dataset was analysed with an LVG model, accounting for optical depth effects. The data cover galactocentric radii R between 0.1 and 16.9 kpc (solar circle at 8.5 kpc). Near the centre of the Galaxy, 18O/17O = 2.88 +/- 0.11. For the galactic disc out to an R of ca. 10 kpc, 18O/17O = 4.16 +/- 0.09. At ca. R = 16.5 kpc, 18O/17O = 5.03 +/- 0.46. Assuming that 18O is synthesised predominantly in high-mass stars (M > 8 Msun), while C17O is mainly a product of lower-mass stars, the ratio from the inner Galaxy indicates a dominance of CNO-hydrogen burni...

  10. Direct Synthesis of ESBO Derivatives-18O Labelled with Dioxirane

    Directory of Open Access Journals (Sweden)

    Stefano La Tegola

    2013-01-01

    Full Text Available This work addresses a new approach developed in our laboratory, consisting in the application of isolated dimethyldioxirane (DDO, 1a labelled with 18O for synthesis of epoxidized glyceryl linoleate (Gly-LLL, 2. We expect that this work could contribute in improving analytical methods for the determination of epoxidized soybean oil (ESBO in complex food matrices by adopting an 18O-labelled-epoxidized triacylglycerol as an internal standard.

  11. Separation of reaction mechanisms at low energy. Study of the reactions: 27Al(d,p) 28Al, 24Mg(d,p) 25Mg, and 24Mg(d, α) 22Na

    International Nuclear Information System (INIS)

    The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction 24Mg(d, α) 22Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of 22Na. The angular distribution of the wide resonance at 15.9 MeV in 26Al has been obtained. (author)

  12. Nuclear molecules and their deexcitation channels, case of Cr{sup 48} generated by the Mg{sup 24} + Mg{sup 24} resonant reaction; Molecules nucleaires et leurs modes de desexcitation: le cas du {sup 48}Cr et de la reaction resonante {sup 24}Mg + {sup 24}Mg

    Energy Technology Data Exchange (ETDEWEB)

    Salsac, M.D

    2006-12-15

    This work is dedicated to the study of the resonance (E = 45,7 MeV, J{sup {pi}} = 36{sup +}, {gamma} = 170 keV) of the Mg{sup 24} + Mg{sup 24} composite nucleus. The PRISMA fragment spectrometer combined with the CLARA gamma detector have been used to study the deexcitation through inelastic channels of the composite system. It is showed that the resonant flux is mainly observed in the inelastic channels involving the contributions 0{sup +}, 2{sup +} and 4{sup +} of the band based on the fundamental state of Mg{sup 24}. This is in good agreement with the theoretical predictions of the molecular model of Uegaki and Abe. Only 30% of the resonant flux has been observed in the inelastic channels and in the transfer channels. The missing flux has been investigated in the fusion/evaporation deexcitation channels with the GASP gamma multi-detector. A weak resonant effect has been highlighted in some residual nuclei such as Ti{sup 45}, Ca{sup 42} and K{sup 39}. A link between the prolate di-nucleus Ca{sup 48} generated in Mg{sup 24} + Mg{sup 24} reaction and a Cr{sup 48} nucleus that has just undergone a Jacobi transition from oblate to prolate, has been discovered. To explain a part of the missing flux it is suggested that the dipolar giant resonance might feed very deformed nuclei through particle emission.

  13. Configuration mixing of mean-field wave-functions projected on angular momentum and particle number; application to 24Mg

    CERN Document Server

    Valor, A; Bonche, P

    2000-01-01

    We present in this paper the general framework of a method which permits to restore the rotational and particle number symmetries of wave functions obtained in Skyrme HF+BCS calculations. This restoration is nothing but a projection of mean-field intrinsic wave functions onto good particle number and good angular momentum. The method allows also to mix projected wave functions. Such a configuration mixing is discussed for sets of HF+BCS intrinsic states generated in constrained calculations with suitable collective variables. This procedure gives collective states which are eigenstates of the particle number and the angular momentum operators and between which transition probabilities are calculated. An application to 24Mg is presented, with mean-field wave functions generated by axial quadrupole constraints. Theoretical spectra and transition probabilities are compared to the experiment.

  14. The 12C* Hoyle state in the inelastic 12C + 12C reaction and in 24Mg* decay

    Science.gov (United States)

    Morelli, L.; Bruno, M.; D'Agostino, M.; Baiocco, G.; Gulminelli, F.; Abbondanno, U.; Barlini, S.; Bini, M.; Casini, G.; Cinausero, M.; Degerlier, M.; Fabris, D.; Gramegna, F.; Mabiala, J.; Marchi, T.; Olmi, A.; Pasquali, G.; Piantelli, S.; Valdré, S.

    2016-08-01

    The reaction 12C + 12C at 95 MeV has been studied at the Legnaro Laboratories of INFN with the GARFIELD + RCo apparatus. Data have been analyzed in order to investigate the decay of the Hoyle state of 12C*. Two different data selections have been made. The first one corresponds to peripheral binary collisions where the quasi-projectile is excited to the Hoyle state and the target has been left in the ground state. The second selection allows for studying central events with the formation of a 24Mg* and the Hoyle state is obtained as a step of the decay chain. The characteristics of the Hoyle state decay are very similar in the two samples and point to a mainly sequential decay through the population of an intermediate 8Begs, with a small contribution (˜1.1%) from simultaneous three α-particle processes.

  15. Separation of reaction mechanisms at low energy. Study of the reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, and {sup 24}Mg(d, {alpha}) {sup 22}Na; Sur la separation des mecanismes de reaction a basse energie. Etude des reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, et {sup 24}Mg(d, {alpha}) {sup 22}Na

    Energy Technology Data Exchange (ETDEWEB)

    Mermaz, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction {sup 24}Mg(d, {alpha}) {sup 22}Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of {sup 22}Na. The angular distribution of the wide resonance at 15.9 MeV in {sup 26}Al has been obtained. (author) [French] Les deux ensembles de distributions angulaires des reactions (d,p) sur Al et Mg, mesures entre 2 et 6 MeV, nous ont permis, en analysant les fluctuations statistiques de sections efficaces, de verifier la possibilite de la separation de leurs valeurs moyennes en deux composantes: l'une 'directe', l'autre due au mecanisme statistique. Avec la meme methode d'analyse nous avons etudie les fonctions d'excitation des premiers groupes alpha de la reaction {sup 24}Mg(d,{alpha}) {sup 22}Na et mis en evidence une structure intermediaire pour la voie de reaction aboutissant au 3eme niveau de {sup 22}Na. Nous avons obtenu la distribution angulaire de la resonance large situee a une energie d'excitation de 15,9 MeV dans {sup 26}Al. (auteur)

  16. Production of scandium-43 and -47 from a powdery calcium oxide target via the (nat/44)Ca(α,x)-channel.

    Science.gov (United States)

    Minegishi, Katsuyuki; Nagatsu, Kotaro; Fukada, Masami; Suzuki, Hisashi; Ohya, Tomoyuki; Zhang, Ming-Rong

    2016-10-01

    We produced (43)Sc and (47)Sc via the (nat/44)Ca(α,x)-channel using a vertical beam coupled with a ceramic target box. After activation, the powdery CaO target material was dissolved in HCl in the target box in situ and remotely recovered as a radio-Sc solution. The respective yields of (43)Sc and (47)Sc following isolation via a precipitation method with a typical 0.22µm sterile filter were 54.8MBq/µAh (1.48mCi/µAh) and 780kBq/µAh (21.1µCi/µAh) at the end of separation (approximately 1.5h from the EOB). In addition, we discuss the recycling of target Ca.

  17. Production of scandium-43 and -47 from a powdery calcium oxide target via the (nat/44)Ca(α,x)-channel.

    Science.gov (United States)

    Minegishi, Katsuyuki; Nagatsu, Kotaro; Fukada, Masami; Suzuki, Hisashi; Ohya, Tomoyuki; Zhang, Ming-Rong

    2016-10-01

    We produced (43)Sc and (47)Sc via the (nat/44)Ca(α,x)-channel using a vertical beam coupled with a ceramic target box. After activation, the powdery CaO target material was dissolved in HCl in the target box in situ and remotely recovered as a radio-Sc solution. The respective yields of (43)Sc and (47)Sc following isolation via a precipitation method with a typical 0.22µm sterile filter were 54.8MBq/µAh (1.48mCi/µAh) and 780kBq/µAh (21.1µCi/µAh) at the end of separation (approximately 1.5h from the EOB). In addition, we discuss the recycling of target Ca. PMID:27472825

  18. The Importance Of Atmospheric {delta} {sup 18}O In Determining Leaf {delta} {sup 18}O In Oak And Pine

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, C.E.; Saurer, M.; Siegwolf, R.T.W.

    2005-03-01

    Strongly {delta} {sup 18}O depleted water vapour was used to study leaf isotopic enrichment and gas exchange properties in a climate-controlled cuvette under a range of environmental conditions. Results show that water vapour strongly influences leaf isotopic composition. This technique was successfully introduced as a novel tool for studying leaf water enrichment. (author)

  19. Elastic and inelastic scattering of 400 MeV polarised deuterons on 12C, 24Mg, 40Ca nuclei

    International Nuclear Information System (INIS)

    This research thesis is based on an experiment of scattering of polarised 400 MeV deuterons on 12C, 24Mg, 40Ca nuclei, performed on the Saturne accelerator. The measured observables are the non-polarised cross section, and the powers of vector and tensor analysis. The author describes the experiment running and the installation, presents the various devices from source to detection and acquisition by the computer system. He reports the experiment compilation: reading of magnetic tapes, assessment and taking into account of the different experimental parameters. The calculation of scattering observables (cross section and powers of analysis) is performed by using experimental data. Spectra of these observables are represented for the different excited states of nuclei, after, should the occasion arise, Gaussian decomposition or background subtraction. The author reports the analysis of the obtained results. Results obtained for the three nuclei are compared between each other, and with scattering data for protons at similar energies which have already been measured. An analysis with a microscopic model is performed and the predictions of this model are compared with the obtained results

  20. Decay studies of 59Cu* formed in the 35Cl + 24Mg reaction using the dynamical cluster-decay model

    Science.gov (United States)

    Karthikraj, C.; Balasubramaniam, M.

    2013-02-01

    The reformulated dynamical cluster-decay model (DCM) is applied to study the decay of odd-A and non-α structured 59Cu* formed in the 35Cl+24Mg reaction at Elab=275 MeV. Here, the temperature (T)-dependent binding energies due to Krappe are used. The roles of Wigner and pairing energies in the fragmentation potential are explicitly shown in this work. For the temperature T=4.1898 MeV corresponding to Elab=275 MeV, the contribution of pairing vanishes and the resulting structure of the fragmentation potential due to Wigner term is shown. In addition to this, we have studied the role of factor α appearing in the inertia part of the equation of motion dictating the mass-transfer process. It is shown that this factor has significant effect in the structure of preformation probability values and hence in turn we see significant changes in the cross sections. We compare the cross sections of the measured charge distributions of the fission fragments for two limiting values of the parameter α with the experimental data. In order to fit the total cross-section values, a linear relation is obtained between the free parameter of the model ▵R and the factor α appearing in the hydrodynamical mass.

  1. Stellar neutrino energy loss rates due to $^{24}$Mg suitable for O+Ne+Mg core simulations

    CERN Document Server

    Nabi, Jameel-Un

    2011-01-01

    Neutrino losses from proto-neutron stars play a pivotal role to decide if these stars would be crushed into black holes or explode as supernovae. Recent observations of subluminous Type II-P supernovae (e.g., 2005cs, 2003gd, 1999br, 1997D) were able to rejuvenate the interest in 8-10 M$_{\\odot}$ stars which develop O+Ne+Mg cores. Simulation results of O+Ne+Mg cores show varying results in converting the collapse into an explosion. The neutrino energy loss rates are important input parameters in core collapse simulations. Proton-neutron quasi-particle random phase approximation (pn-QRPA) theory has been used for calculation of neutrino energy loss rates due to $^{24}$Mg in stellar matter. The rates are presented on a detailed density-temperature grid suitable for simulation purposes. The calculated neutrino energy loss rates are enhanced up to more than one order of magnitude compared to the shell model calculations and favor a lower entropy for the core of these massive stars.

  2. Detailed microscopic calculation of stellar electron and positron capture rates on $^{24}$Mg for O+Ne+Mg core simulations

    CERN Document Server

    Nabi, Jameel-Un

    2014-01-01

    Few white dwarfs, located in binary systems, may acquire sufficiently high mass accretion rates resulting in the burning of carbon and oxygen under nondegenerate conditions forming a O+Ne+Mg core. These O+Ne+Mg cores are gravitationally less bound than more massive progenitor stars and can release more energy due to the nuclear burning. They are also amongst the probable candidates for low entropy r-process sites. Recent observations of subluminous Type II-P supernovae (e.g., 2005cs, 2003gd, 1999br, 1997D) were able to rekindle the interest in 8 -- 10 M$_{\\odot}$ which develop O+Ne+Mg cores. Microscopic calculations of capture rates on $^{24}$Mg, which may contribute significantly to the collapse of O+Ne+Mg cores, using shell model and proton-neutron quasiparticle random phase approximation (pn-QRPA) theory, were performed earlier and comparisons made. Simulators, however, may require these capture rates on a fine scale. For the first time a detailed microscopic calculation of the electron and positron captur...

  3. Modeling mountainous fens water regime using 18-O.

    Science.gov (United States)

    Anda, Martin Å.; Ípová, Dora Å.; Dohnal, Michal; Císlerová, Milena

    2010-05-01

    Mountainous fens are important hydrological component of the headwater catchments in Jizera Mountains, The Czech Republic. Experimental catchment Uhlířská (1.78 km2) is formed by paleozolic crystalline bedrock overlaid by shallow highly permeable Cambisol on the hillslopes, whereas the thick saturated glacial deposits in the valley are overlaid by Histosols. Standard meteorological and hydrological monitoring is supplemented by measurements of the soil moisture, soil pore water suction, water table fluctuation in the saturated riparian zone of Černá Nisa creek. Water sampling for the 18O and 2H isotopes is performed throughout the catchment. Numerical simulation was performed with S1D code for the period May 2007-September 2008. The model is based on Richards' equation for vertical soil water flow and the advection-dispersion equation for transport of stable oxygen isotope 18O. Hourly rainfall or daily snowmelt intensities are introduced as an upper boundary condition, the measured groundwater table fluctuation serves as a time variable prescribed head at the bottom boundary. The intensity of the root water uptake due to transpiration is assumed as a zone sink term. Daily values of δ18O in the rain and weekly δ18O values of the melting snow, together with the hourly interpolated monthly values of δ18O in the groundwater, serve as the transport boundary conditions. Measured soil hydraulic parameters were adjusted based on suction heads and δ18O variations in observation points representing the soil tensiometers and suction cups. Results of the model demonstrate a strong mixing of water in the root zone of the peat profile, where evapotranspiration takes place. Process of deeper percolation is limited by the high degree of saturation of the peat in combination with its low hydraulic conductivity. The seasonal water percolation is estimated according to the results of the isotope transport down to 70 cm below the surface. The S1D model with the use of

  4. C18O Depletion in Starless Cores in Taurus

    CERN Document Server

    Ford, Amanda Brady

    2011-01-01

    We present here findings for C18O depletion in eight starless cores in Taurus: TMC-2, L1498, L1512, L1489, L1517B, L1521E, L1495A-S, and L1544. We compare observations of the C18O J=2-1 transition taken with the ALMA prototype receiver on the Heinrich Hertz Submillimeter Telescope to results of radiative transfer modeling using RATRAN. We use temperature and density profiles calculated from dust continuum radiative transfer models to model the C18O emission. We present modeling of three cores, TMC-2, L1489, and L1495A-S, which have not been modeled before and compare our results for the five cores with published models. We find that all of the cores but one, L1521E, are substantially depleted. We also find that varying the temperature profiles of these model cores has a discernable effect, and varying the central density has an even larger effect. We find no trends with depletion radius or depletion fraction with the density or temperature of these cores, suggesting that the physical structure alone is insuff...

  5. Synthesis of 8-[[sup 18]O]hydroxy-2'-deoxyguanosine

    Energy Technology Data Exchange (ETDEWEB)

    Hermanns, R.C.A.; Zomer, G.; Jacquemijns, M.; Stavenuiter, J.F.C.; Teixeira, A.J.R.; Werken, G. van de (National Inst. of Public Health and Environmental Protection, Bilthoven (Netherlands)); Westra, J.G. (Nederlands Kanker Inst. ' Antoni van Leeuwenhoekhuis' , Amsterdam (Netherlands))

    1994-02-01

    8-[[sup 18]O]Hydroxy-2'-deoxyguanosine was synthesized starting from 8-bromo-2'-deoxyguanosine and the sodium salt of [[sup 18]O]benzyl alcohol, resulting in the intermediate 8-[[sup 18]O]benzyloxy-2'-deoxyguanosine. Subsequent reduction by catalytic transfer hydrogenation, yielded the desired product 8-[[sup 18]O]hydroxy-2'-deoxyguanosine. (author).

  6. Investigating the past and recent δ18O-accumulation relationship seen in Greenland ice cores

    OpenAIRE

    Buchardt, S. L.; Clausen, H. B.; Vinther, B. M.; Dahl-Jensen, D.

    2012-01-01

    Decadal means of δ18O and accumulation rates from 52 ice core locations in Greenland are presented. The accumulation rates are derived from annual layers determined in the δ18O curve. Investigation of the δ18O-accumulation relationship across the ice divide reveals a significant Foehn effect with anticorrelation of δ18O and accumulation rate on the lee side of the divide in Southern Greenland, while no effect is seen in Central Greenl...

  7. Temporal variations of δ18O of atmospheric water vapor at Delingha

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Oxygen stable isotope of atmospheric water vapor is widely used to study the modern process of cli- mate. Atmospheric water vapor samples were collected at Dlingha, northeast of Tibetan Plateau during the period from July 2005 to February 2006. The variation of δ18O and the relationships between δ18O and both the temperature and specific humidity are analyzed in this paper. Results show that the sea- sonal variation of δ18O of atmospheric water vapor at Delingha is remarkable with higher δ18O in summer and lower δ18O in winter. The temporal variation of vapor δ18O shows obvious fluctuations, with magnitude of over 37‰. The daily variation of the δ18O is highly correlated with air temperature. The relationship between δ18O and atmospheric water vapor content is complex. Study shows that δ18O of atmospheric water vapor is positively correlated with specific humidity in winter in seasonal scale and inversely correlated with specific humidity in summer rainy period. The δ18O values of at- mospheric water vapor are lower than those of precipitation at Delingha, and the average difference is 10.7‰. Variations of δ18O of atmospheric water vapor is also found to be affected by precipitation events, The model results show that the precipitation effect could have caused the vapor δ18O in the raining season to lower by 7% in average in July and August.

  8. Espiritu Santo, Vanuatu Stable Isotope (delta 18O, delta 13C) Data for 1806 to 1979

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Site: Espiritu Santo Island, Vanuatu, 15S, 167E. 173 year record of d18O and d13C. Variable names: QSR Age, QSR 13C, QSR 18O, GRL Age, GRL Qtrly 13C, GRL Qtrly 18O,...

  9. Semi empirical formula for electronic stopping power determination of 24Mg, 27Al and 28Si ions crossing Formvar foil in the ion energy domain of LSS theory

    Science.gov (United States)

    Guesmia, A.; Ammi, H.; Mammeri, S.; Dib, A.; Pineda-Vargas, C. A.; Msimanga, M.; Hedibel, M.

    2014-03-01

    We have determined continuous stopping power of heavy ions in thin Formvar foil for 28Si, 27Al and 24Mg ions over an energy range of (0.1-0.5) MeV/nucleon. Heavy Ions Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with time of flight (ToF) spectrometer has been used to measure energy loss of charged particles in this thin absorber. Lindhard, Scharff and Schiott (LSS) theory compared with the corresponding determined stopping values in Formvar, shows significantly large deviations. However, a novel semi empirical expression has been proposed here and tested for better stopping power calculations at low velocity in the ion energy domain of LSS theory for 28Si, 27Al and 24Mg ions crossing thin Formvar foil. The results were compared to the obtained experimental stopping power data, predictions of LSS theory and also to those generated by SRIM-2010 computer code. The obtained results exhibit good agreement with experimental data.

  10. Extreme alpha-clustering in the 18O nucleus

    CERN Document Server

    Johnson, E D; Goldberg, V Z; Brown, S; Robson, D; Crisp, A M; Cottle, P D; Fu, C; Giles, J; Green, B W; Kemper, K W; Lee, K; Roeder, B T; Tribble, R E

    2009-01-01

    The structure of the 18O nucleus at excitation energies above the alpha decay threshold was studied using 14C+alpha resonance elastic scattering. A number of states with large alpha reduced widths have been observed, indicating that the alpha-cluster degree of freedom plays an important role in this N not equal Z nucleus. However, the alpha-cluster structure of this nucleus is very different from the relatively simple pattern of strong alpha-cluster quasi-rotational bands in the neighboring 16O and 20Ne nuclei. A 0+ state with an alpha reduced width exceeding the single particle limit was identified at an excitation energy of 9.9+/-0.3 MeV. We discuss evidence that states of this kind are common in light nuclei and give possible explanations of this feature.

  11. Terahertz spectroscopy of ground state HD18O

    Science.gov (United States)

    Yu, Shanshan; Pearson, John C.; Drouin, Brian J.; Miller, Charles E.; Kobayashi, Kaori; Matsushima, Fusakazu

    2016-10-01

    Terahertz absorption spectroscopy was employed to measure the ground state pure rotational transitions of the water isotopologue HD18O . A total of 105 pure rotational transitions were observed in the 0.5-5.0 THz region with ∼ 100 kHz accuracy for the first time. The observed positions were fit to experimental accuracy using the Euler series expansion of the asymmetric-top Hamiltonian together with the literature Microwave, Far-IR and IR data in the ground state and ν2 . The new measurements and predictions reported here support the analysis of astronomical observations by high-resolution spectroscopic telescopes such as SOFIA and ALMA where laboratory rest frequencies with uncertainties of 1 MHz or less are required for proper analysis of velocity resolved astrophysical data.

  12. An attempt of application of short lived 44K activity induced in the 44Ca(n,p)44K reaction using 14 MeV neutrons for total body calcium assessment in human subject

    International Nuclear Information System (INIS)

    The status of in vivo neutron activation analysis techniques for the measurement of total body calcium in human subject is reviewed. Relevant data on the nuclear characteristics of calcium isotopes during interaction with neutrons ranging from slow up to 14 MeV neutrons are presented. Physical aspects of the measurement of in vivo total body calcium (TBCa) using 44K activity induced in the 44Ca(n,p)44K(T1/2=22.3 min) reaction by 14 MeV neutrons are discussed. The measurement of delayed γ-ray emitted during decay of activities induced in enriched 44Ca, natCa, phantom filled with water solution of natural calcium and skeletal arm are considered. Results of measurements on the phantom and skeletal arm indicate a possibility to measure the TBCa using the 44K activity. (author)

  13. 2H and 18O Freshwater Isoscapes of Scotland

    Science.gov (United States)

    Meier-Augenstein, Wolfram; Hoogewerff, Jurian; Kemp, Helen; Frew, Danny

    2013-04-01

    Scotland's freshwater lochs and reservoirs provide a vital resource for sustaining biodiversity, agriculture, food production as well as for human consumption. Regular monitoring of freshwaters by the Scottish Environment Protection Agency (SEPA) fulfils legislative requirements with regards to water quality but new scientific methods involving stable isotope analysis present an opportunity combining these mandatory monitoring schemes with fundamental research to inform and deliver on current and nascent government policies [1] through gaining a greater understanding of Scottish waters and their importance in the context of climate change, environmental sustainability and food security. For example, 2H and 18O isoscapes of Scottish freshwater could be used to underpin research and its applications in: • Climate change - Using longitudinal changes in the characteristic isotope composition of freshwater lochs and reservoirs as proxy, isoscapes will provide a means to assess if and how changes in temperature and weather patterns might impact on precipitation patterns and amount. • Scottish branding - Location specific stable isotope signatures of Scottish freshwater have the potential to be used as a tool for provenancing and thus protecting premium Scottish produce such as Scottish beef, Scottish soft fruit and Scottish Whisky. During 2011 and 2012, with the support of SEPA more than 110 samples from freshwater lochs and reservoirs were collected from 127 different locations across Scotland including the Highlands and Islands. Here we present the results of this sampling and analysis exercise isotope analyses in form of 2H and 18O isoscapes with an unprecedented grid resolution of 26.5 × 26.5 km (or 16.4 × 16.4 miles). [1] Adaptation Framework - Adapting Our Ways: Managing Scotland's Climate Risk (2009): Scotland's Biodiversity: It's in Your Hands - A strategy for the conservation and enhancement of biodiversity in Scotland (2005); Recipe For Success - Scotland

  14. Semi empirical formula for electronic stopping power determination of 24Mg, 27Al and 28Si ions crossing Formvar foil in the ion energy domain of LSS theory

    International Nuclear Information System (INIS)

    We have determined continuous stopping power of heavy ions in thin Formvar foil for 28Si, 27Al and 24Mg ions over an energy range of (0.1–0.5) MeV/nucleon. Heavy Ions Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with time of flight (ToF) spectrometer has been used to measure energy loss of charged particles in this thin absorber. Lindhard, Scharff and Schiott (LSS) theory compared with the corresponding determined stopping values in Formvar, shows significantly large deviations. However, a novel semi empirical expression has been proposed here and tested for better stopping power calculations at low velocity in the ion energy domain of LSS theory for 28Si, 27Al and 24Mg ions crossing thin Formvar foil. The results were compared to the obtained experimental stopping power data, predictions of LSS theory and also to those generated by SRIM-2010 computer code. The obtained results exhibit good agreement with experimental data. - Highlights: • Experimental stopping data has been obtained by using Heavy Ions Elastic Recoil Detection Analysis technique with Time of Flight spectrometer. • A new semi-empirical stopping formula based on LSS theory has been proposed for 28Si, 27Al and 24 Mg ions in Formvar foil. • This expression well fit the experimental stopping data at low energy in LSS domain

  15. Monsoon influence on planktic δ18O records from the South China Sea

    Science.gov (United States)

    Wang, Pinxian; Li, Qianyu; Tian, Jun; He, Juan; Jian, Zhimin; Ma, Wentao; Dang, Haowen

    2016-06-01

    While the benthic δ18O records from many South China Sea sites mimic the SPECMAP/LR04 standard, their paired planktic δ18O curves differ by comparable values at negative peaks corresponding to interstadials, especially between MIS 5.1, 5.3, 5.5, 6.5, and 7.3. Similar planktic δ18O records also occur in some other low-latitude oceans under monsoon influence. Because neither temperature nor salinity effects can fully account for the variations of such δ18O records after derivation from the SPECMAP/LR04 standard, variations in the rain water δ18O affected by regional hydroclimate changes are considered to have played an important role. In contrast to the SPECMAP/LR04 standard δ18O curve prevailed by 100-kyr cycles, these regional planktic δ18O curves are distinguished by 20-kyr precession signal, showing partial similarity to the δ18O records of atmospheric oxygen in polar ice-core bubbles and in stalagmite calcite. We speculate that the common features of these three independent δ18O records are indicative of the effect of evolving hydrological cycling driven by monsoon circulation in low latitudes.

  16. Dirac Coupled-channel Analyses of Polarized Proton Scatterings to the 2$^+$ Gamma Vibrational Band in $^{24}$Mg and $^{26}$Mg

    CERN Document Server

    Shim, Sugie

    2016-01-01

    Dirac coupled channel calculations are performed phenomenologically for the high-lying excited states that belong to the 2$^+$ gamma vibrational band at the 800-MeV polarized proton inelastic scatterings from the s-d shell nuclei, $^{24}$Mg and $^{26}$Mg. Optical potential model is used and scalar and time-like vector potentials are considered as direct potentials. First-order vibrational collective models are used to obtain the transition optical potentials in order to accommodate the high-lying excited vibrational collective states. The complicated Dirac coupled channel equations are solved phenomenologically to reproduce the differential cross section and analyzing power data by varying the optical potential and deformation parameters. It is found that the relativistic Dirac coupled channel calculation could describe the high-lying excited states of the 2$^+$ gamma vibrational band at the 800-MeV polarized proton inelastic scatterings from s-d shell nuclei $^{24}$Mg and $^{26}$Mg reasonably well, showing b...

  17. 24Mg(α,γ)28Si reaction at alpha-particle energies from 3.2 to 6.2 MeV

    International Nuclear Information System (INIS)

    The 24Mg(α,γ)28Si reaction has been used to study excited states in 28Si. Targets of enriched 24Mg on a tantalum backing were bombarded by an α-particle beam from the CN Van de Graaff accelerator of The Pennsylvania State University. A large NaI(Tl) detector was placed immediately adjacent to the target in order to increase the probability of summing of the signals from different members of a cascade; windows were set for transitions to the ground state and the first few excited states. The energy of the α-particles was increased in steps of 2 to 5 keV from 3.2 to 6.2 MeV. Thirty-two resonances were located by sharp increases in the number of events recorded. At each resonance a spectrum was taken using a 55 cm3 Ge(Li) detector placed 5 cm from the target at an angle of 550 to the beam axis, the data being recorded on a PDP-15 on-line computer. The spectra were analyzed off-line using the program SAMPO of the Lawrence Berkeley Laboratory. (Diss. Abstr. Int., B)

  18. γ-ray production by proton and α-particle induced reactions on 12C, 16O, 24Mg, and Fe

    International Nuclear Information System (INIS)

    γ-ray production cross sections for proton and α-particle interactions with 12C, 16O, 24Mg, and Fe have been measured in the energy range 5-25 MeV with proton beams and 5-40 MeV with α-particle beams. Isotopically pure foils of 24Mg and foils of natural isotopical composition of C, MgO, and Fe have been used. γ-ray angular distributions were obtained with five high-purity Ge detectors with bismuth germanate Compton shields placed at angles of 45 deg. to 157.5 deg. Cross sections for more than 50 different γ-ray transitions were extracted, and for many of them no data have been published before. Comparison of present data with data available in the literature shows mostly good to excellent agreement. In addition to the production cross sections, high-statistics, low-background line shapes of the 4.438 MeV 12C γ ray from inelastic scattering off 12C and spallation of 16O were obtained. Comparison with nuclear reaction calculations shows that these data place interesting constraints on nuclear reaction models

  19. Study of two- and multi-particle correlations in 12C+24Mg and 12C+208Pb reactions at E=35 AMeV

    Directory of Open Access Journals (Sweden)

    Quattrocchi L.

    2016-01-01

    Full Text Available Two and multi particle correlations from the decay of sources produced in 12C+24Mg and 12C+208Pb collisions at E=35 AMeV have been studied by using the forward part (1° < θlab < 30° of the CHIMERA multi-detector. Correlations and invariant mass spectroscopy are used to explore simultaneous and sequential decays of resonances in light isotopes with Z∼3-6, produced in peripheral collisions via the break-up of excited quasi-projectiles. Among them we mention 5Li, 6Li, 6Be, 8Be and the astrophysically important state in 12C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.

  20. $^{8}$Be, $^{12}$C, $^{16}$O, $^{20}$Ne, $^{24}$Mg, and $^{32}$S nuclei and alpha clustering within a generalized liquid drop model

    CERN Document Server

    Royer, G; Eudes, P

    2015-01-01

    The potential energy governing the shape and the entrance and decay channels of the 12 C, 16 O, 20 Ne, 24 Mg, and 32 S 4n-nuclei has been determined within a generalized liquid drop model. Different three-dimensional and planar shapes have been investigated: linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octogon and cube. The rms radii of the linear chains are higher than the experimental rms radii of the ground states. The binding energies of the planar shapes at the contact point are lower than the ones of the three-dimensional configurations. The a particle plus A-4 daughter configuration leads always to the lowest potential barrier relatively to the sphere configuration.

  1. Clustering effects in fusion evaporation reactions with light even-even N = Z nuclei. The 24Mg and 28Si cases

    International Nuclear Information System (INIS)

    In the recent years, cluster structures have been evidenced in many ground and excited states of light nuclei [1, 2]. Within the currently ongoing experimental campaign by the NUCL-EX collaboration we have measured the 12C+12C and 14N+10B reactions at 95 MeV and 80 MeV respectively, and compared experimental data corresponding to complete fusion of target and projectile into an excited 24Mg nucleus to the results of a pure statistical model[3, 4]. We found clear deviations from the statstical model in the decay pattern: emission channels involving multiple α particles are more probable than expected from a purely statistical behavior. To continue the investigation on light systems, we have recentely measured the 16O+12C reaction at three different beam energies, namely Ebeam = 90, 110 and 130 MeV

  2. Clustering effects in fusion evaporation reactions with light even-even N = Z nuclei. The {sup 24}Mg and {sup 28}Si cases

    Energy Technology Data Exchange (ETDEWEB)

    Morelli, L., E-mail: luca.morelli@bo.infn.it; D’Agostino, M.; Bruno, M. [Dipartimento di Fisica e Astronomia dell’Università and INFN, Bologna (Italy); Baiocco, G. [Dipartimento di Fisica dell’Università and INFN, Pavia (Italy); Gulminelli, F. [CNRS, LPC, Caen, France and ENSICAEN, Caen (France); Cinausero, M.; Gramegna, F.; Marchi, T. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Padova) (Italy); Degerlier, M. [University of Nevsehir, Physics Department, Nevsehir (Turkey); Fabris, D. [INFN, Sezione di Padova, Padova (Italy); Barlini, S.; Bini, M.; Casini, G.; Gelli, N.; Olmi, A.; Pasquali, G.; Piantelli, S. [Dipartimento di Fisica e Astronomia dell’Università and INFN, Firenze (Italy)

    2015-10-15

    In the recent years, cluster structures have been evidenced in many ground and excited states of light nuclei [1, 2]. Within the currently ongoing experimental campaign by the NUCL-EX collaboration we have measured the {sup 12}C+{sup 12}C and {sup 14}N+{sup 10}B reactions at 95 MeV and 80 MeV respectively, and compared experimental data corresponding to complete fusion of target and projectile into an excited {sup 24}Mg nucleus to the results of a pure statistical model[3, 4]. We found clear deviations from the statstical model in the decay pattern: emission channels involving multiple α particles are more probable than expected from a purely statistical behavior. To continue the investigation on light systems, we have recentely measured the {sup 16}O+{sup 12}C reaction at three different beam energies, namely E{sub beam} = 90, 110 and 130 MeV.

  3. Geography and vintage predicted by a novel GIS model of wine delta18O.

    Science.gov (United States)

    West, Jason B; Ehleringer, James R; Cerling, Thure E

    2007-08-22

    Wine hydrogen and oxygen stable isotopes record the climatic conditions experienced by the grape vine and the isotopic composition of the vine's source water during berry development. As such, stable isotopes have been explored extensively for use in detecting wine adulteration or for independently verifying claims of origin. We present the results of a study designed to evaluate the relationships between wine water delta18O and spatial climate and precipitation delta18O patterns across the winegrape-growing regions of Washington, Oregon, and California. Retail wines produced from typically small vineyards across these regions were obtained from the 2002 vintage, and the delta18O of wine water was analyzed using a CO2 equilibration method. Significant correlations were observed between the measured wine water delta18O from 2002 and the long-term average precipitation delta18O and late season 2002 climate, based on a spatial join with continuous geographic information system (GIS) maps of these drivers. We then developed a regression model that was implemented spatially in a GIS. The GIS model is the first of its kind and allows spatially explicit predictions of wine delta18O across the region. Because high spatial resolution monthly climate layers are now available for many years, wine delta18O could be modeled for previous years. We therefore tested the model by executing it for specific years and comparing the model predictions with previously published results for wine delta18O from seven vintages from Napa and Livermore Valleys, California. With the exception of one year, an anomaly potentially related to the effects of El Niño on precipitation isotopic composition, the model predicted well the wine delta18O for both locations for all vintages and generally reflected the consistent enrichment of wine from Napa relative to Livermore. Our results suggest that wine water delta18O records both source water delta18O and climate during the late stages of winegrape

  4. Body composition among Sri Lankan infants by 18*O dilution method and the validity of anthropometric equations to predict body fat against 18*O dilution

    Science.gov (United States)

    Body composition indicators provide a better guidance for growth and nutritional status of the infants. This study was designed to (1) measure the body composition of the Sri Lankan infants using a reference method, the 18*O dilution method; (2) calculate the body fat content of the infants using pu...

  5. Barbados Oxygen Isotope Data (delta 18O) for the Late Pleistocene

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Coral-based delta18O time-series derived from measurements made on submerged or drowned coral reef sequence. The core samples used have been described elsewhere...

  6. Mahe, Seychelles Stable Isotope (delta 18O) Data for 1846 to 1995

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seychelles coral oxygen-18 time series, data are monthly values of d18O from July 1846 to February 1995 from a 3-m Porites lutea coral colony collected from Beau...

  7. Malindi, Kenya Stable Isotope Data (delta 18O, delta 13C) for 1801-1994

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Malindi annual oxygen isotopic composition, 1801-1994. Notes on the data: File includes columns for Year AD, Coral d18O, and SST (degrees C). The SST data are...

  8. Enhancing the Accuracy of Carbonate δ18O and δ13C Measurements by SIMS

    Science.gov (United States)

    Orland, I. J.; Kozdon, R.; Linzmeier, B.; Wycech, J.; Sliwinski, M.; Kitajima, K.; Kita, N.; Valley, J. W.

    2015-12-01

    The precision and accuracy of carbonate δ18O & δ13C analysis by multicollector SIMS is well established if standards match samples in structure and major/minor element chemistry. However, low-T- and bio-carbonates used to construct paleoclimate archives can include complex internal structures and some samples analyzed at WiscSIMS (and other SIMS labs) have a consistent, sample-dependent offset between average SIMS δ18O measurements and bulk δ18O analyses by phosphoric-acid digestion. The offset is typically hydrogen peroxide), for which there is no agreed procedure in conventional bulk analyses. For SIMS analyses, pre-treatments had varied influence on the δ18O value, [16O1H], the concentration of "organic markers" like 12C14N and 31P, and mineralogy (of aragonite samples).

  9. Ras Umm Sidd Oxygen Isotope (delta 18O) Data for 1750 to 1995

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ras Umm Sidd bimonthly coral oxygen isotope data (coral core RUS-95). Notes on the data: File (Ras Umm Sidd d18O.txt.) includes columns for Year AD (bimonthly...

  10. Dentine oxygen isotopes (δ (18)O) as a proxy for odontocete distributions and movements.

    Science.gov (United States)

    Matthews, Cory J D; Longstaffe, Fred J; Ferguson, Steven H

    2016-07-01

    Spatial variation in marine oxygen isotope ratios (δ (18)O) resulting from differential evaporation rates and precipitation inputs is potentially useful for characterizing marine mammal distributions and tracking movements across δ (18)O gradients. Dentine hydroxyapatite contains carbonate and phosphate that precipitate in oxygen isotopic equilibrium with body water, which in odontocetes closely tracks the isotopic composition of ambient water. To test whether dentine oxygen isotope composition reliably records that of ambient water and can therefore serve as a proxy for odontocete distribution and movement patterns, we measured δ (18)O values of dentine structural carbonate (δ (18) OSC) and phosphate (δ (18) OP) of seven odontocete species (n = 55 individuals) from regional marine water bodies spanning a surface water δ (18)O range of several per mil. Mean dentine δ (18) OSC (range +21.2 to +25.5‰ VSMOW) and δ (18) OP (+16.7 to +20.3‰) values were strongly correlated with marine surface water δ (18)O values, with lower dentine δ (18) OSC and δ (18) OP values in high-latitude regions (Arctic and Eastern North Pacific) and higher values in the Gulf of California, Gulf of Mexico, and Mediterranean Sea. Correlations between dentine δ (18) OSC and δ (18) OP values with marine surface water δ (18)O values indicate that sequential δ (18)O measurements along dentine, which grows incrementally and archives intra- and interannual isotopic composition over the lifetime of the animal, would be useful for characterizing residency within and movements among water bodies with strong δ (18)O gradients, particularly between polar and lower latitudes, or between oceans and marginal basins.

  11. Climatic significance of δ18O records from precipitation on the western Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    YU WuSheng; MA YaoMing; SUN WeiZhen; WANG Yu

    2009-01-01

    Analysis of daily precipitation samples for stable oxygen isotopes (δ18O) collected at the Shiquanhe and Gêrzê (Gaize,Gertse) stations in the Ngari (Ali) region on the western Tibetan Plateau indicates that air temperature affects the δ18O variations in precipitation at these stations,in summer,Shiquanhe and Gêrzê show strongly similar trends in precipitation δ18O,especially in simultaneous precipitation events.Moreover,both stations experienced low δ18O values in precipitation during the active monsoon period,resulting from the southwest monsoon (the summer phase of the Indian monsoon).However,during the break monsoon period (during the summer rainy season,when the monsoon circulation is disrupted),δ18O values in summer precipitation remain relatively high and local moisture recycling generally controls the moisture sources.Air temperature correlations with δ18O strengthen during the non-monsoon period (January-June,and October-December) due to continental air masses and the westerlies.In addition,evaporation also influences the δ18O variations in precipitation.The observed temporal and spatial variations of δ18O in precipitation on the western Tibetan Plateau and adjacent regions show that the late May and early June-the late August and early September time frame provides an important period for the transportation of moisture from various sources on the Tibetan Plateau,and that the region of the West Kunlun-Tanggula Ranges acts as a significant climatic divide on the Plateau,perhaps for all of western China.

  12. Pulmonary NO and C18O2 uptake during pressure-induced lung expansion in rabbits.

    Science.gov (United States)

    Heller, Hartmut; Schuster, Klaus-Dieter

    2007-01-01

    In artificially ventilated animals we investigated the dependence of the pulmonary diffusing capacities of nitric oxide (NO) and doubly 18O-labeled carbon dioxide (DLNO, DLC18O2) on lung expansion with respect to ventilator-driven increases in intrapulmonary pressure. For this purpose we applied computerized single-breath experiments to 11 anesthetized paralyzed rabbits (weight 2.8-3.8 kg) at various alveolar volumes (45-72 ml) by studying the almost entire inspiratory limb of the respective pressure/volume curves (intrapulmonary pressure: 6-27 cmH2O). The animals were ventilated with room air, employing a computerized ventilatory servo-system that we designed to maintain mechanical ventilation and to execute the particular lung function tests automatically. Each single-breath maneuver was started from residual volume (13.5+/-2 ml, mean+/-SD) by inflating the rabbit lungs with 35-55 ml indicator gas mixture containing 0.05% NO in N2 or 0.9% C18O2 in N2. Alveolar partial pressures of NO and C18O2 were measured by respiratory mass spectrometry. Values of DLNO and DLC18O2 ranged between 1.55 and 2.49 ml/(mmHg min) and 11.7 and 16.6 ml/(mmHg min), respectively. Linear regression analyses yielded a significant increase in DLNO with simultaneous increase in alveolar volume (P<0.005) and intrapulmonary pressure (P<0.023) whereas DLC18O2 was not improved. Our results suggest that the ventilator-driven lung expansion impaired the C18O2 blood uptake conductance, finally compensating for the beneficial effect of the increase in alveolar volume on DLC18O2 values.

  13. Synthesis of oxygen-18 enriched phenol and naphthol from /sup 18/O/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Walker, T.E.; Goldblatt, M.

    1984-01-01

    Phenols enriched with oxygen-18 can be synthesized using an acid exchange reaction in H/sub 2//sup 18/O at elevated temperature, however, to obtain highly enriched products very large quantities of water must be used and recycled. Grignard reagents will react readily with oxygen gas with almost no isotopic dilution to produce the /sup 18/O enriched alcohol or phenol. Aromatic Grignards do not produce as high a yield as the aliphatic Grignards, however, both provide convenient routes to labeled products. The yield of naphthol from an aryl halide can be improved by the addition of an aliphatic halide (which produces the alcohol as a by product), however, the yield of naphthol from /sup 18/O/sub 2/ gas is not improved by this approach. Either 1-bromonaphthalene or bromobenzene was converted into the Grignard reagent and reacted with oxygen-18 enriched gas at 0/sup 0/ in a sealed reaction system. The reaction was worked up in the conventional manner and the yields from /sup 18/O/sub 2/ were 34% for (/sup 18/O) phenol and 23% for 1-(/sup 18/O)naphthol. 15 references, 1 figure, 1 table.

  14. Late-Pleistocene precipitation δ18O interpolated across the global landmass

    Science.gov (United States)

    Jasechko, Scott

    2016-08-01

    Global water cycles, ecosystem assemblages, and weathering rates were impacted by the ˜4°C of global warming that took place over the course of the last glacial termination. Fossil groundwaters can be useful indicators of late-Pleistocene precipitation isotope compositions, which, in turn, can help to test hypotheses about the drivers and impacts of glacial-interglacial climate changes. Here, a global catalog of 126 fossil groundwater records is used to interpolate late-Pleistocene precipitation δ18O across the global landmass. The interpolated data show that extratropical late-Pleistocene terrestrial precipitation was near uniformly depleted in 18O relative to the late Holocene. By contrast, tropical δ18O responses to deglacial warming diverged; late-Pleistocene δ18O was higher-than-modern across India and South China but lower-than-modern throughout much of northern and southern Africa. Groundwaters that recharged beneath large northern hemisphere ice sheets have different Holocene-Pleistocene δ18O relationships than paleowaters that recharged subaerially, potentially aiding reconstructions of englacial transport in paleo ice sheets. Global terrestrial late-Pleistocene precipitation δ18O maps may help to determine 3-D groundwater age distributions, constrain Pleistocene mammal movements, and better understand glacial climate dynamics.

  15. Regional scale high resolution δ18O prediction in precipitation using MODIS EVI.

    Directory of Open Access Journals (Sweden)

    Wei-Ping Chan

    Full Text Available The natural variation in stable water isotope ratio data, also known as water isoscape, is a spatiotemporal fingerprint and a powerful natural tracer that has been widely applied in disciplines as diverse as hydrology, paleoclimatology, ecology and forensic investigation. Although much effort has been devoted to developing a predictive water isoscape model, it remains a central challenge for scientists to generate high accuracy, fine scale spatiotemporal water isoscape prediction. Here we develop a novel approach of using the MODIS-EVI (the Moderate Resolution Imagining Spectroradiometer-Enhanced Vegetation Index, to predict δ(18O in precipitation at the regional scale. Using a structural equation model, we show that the EVI and precipitated δ(18O are highly correlated and thus the EVI is a good predictor of precipitated δ(18O. We then test the predictability of our EVI-δ(18O model and demonstrate that our approach can provide high accuracy with fine spatial (250×250 m and temporal (16 days scale δ(18O predictions (annual and monthly predictabilities [r] are 0.96 and 0.80, respectively. We conclude the merging of the EVI and δ(18O in precipitation can greatly extend the spatial and temporal data availability and thus enhance the applicability for both the EVI and water isoscape.

  16. Indicators of δ13C and δ18O of gas hydrate-associated sediments

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The analyses of δ13C and δ18O of gas hydrate-associated sediments from two cores on Hydrate Ridge in Cascadia convergent margin offshore Oregon, eastern North Pacific show the values of d 13C from -29.81‰ to -48.28‰ (PDB) and d 18O from 2.56‰ to 4.28‰ (PDB), which could be plotted into a group called typical carbonate minerals influenced by the methane in cold venting. Moreover, the values of d 13C and d 18O show a consistent trend in both cores from top to bottom with increasing of d 13C and decreasing of d 18O. This trend could be explained as an effect caused by the anaerobic oxidation of methane (AOM) in depth and the oxygen fraction during the formation of gas hydrate in depth together. These characteristics of d 13C and d 18O indicate that the gas hydrate-associated sediments are significantly different from the normal marine carbonates, and they are deeply influenced by the formation and evolution of gas hydrate. So, the distinct characteristics of d 13C and d 18O of gas hydrate-associated sediments could be undoubtedly believed as one of parameters to determine the presence of gas hydrates in other unknown marine sediment cores.

  17. The MMCO-EOT conundrum: same benthic δ18O, different CO2

    Science.gov (United States)

    Stap, Lennert; van de Wal, Roderik; de Boer, Bas; Bintanja, Richard; Lourens, Lucas

    2016-04-01

    Knowledge on temporal variations of Earth's climate over the past 38 Myr largely stems from benthic δ18O records. These records are difficult to interpret, however, since they document combined effects of deep-sea temperature and ice volume variations. Information on CO2 is expanding, but remains highly uncertain and intermittent. Attempts to determine the long-term relations between δ18O, sea level and CO2 from proxy data suffer from paucity of data and apparent inconsistency among different records. One outstanding issue is the difference recorded in proxy CO2 data between the Eocene-Oligocene boundary (EOT) and the Middle-Miocene Climatic Optimum (MMCO), while similar levels of benthic δ18O are shown during these time periods. Here, we take a model-based approach to deconvolute the benthic δ18O signal, and reconcile knowledge on benthic δ18O, sea level, CO2 and temperature. We obtain continuous and mutually consistent 38-Myr-long simulations of these variables, by forcing a coupled ice sheet-climate model inversely with benthic δ18O observations. We investigate the factors influencing Arctic and Antarctic polar amplification, and the relation between sea level and CO2. Furthermore, we show that different CO2 between the EOT and MMCO, as indicated by proxy data, can only be obtained if we impose erosion or tectonic movement of the Antarctic continent over time.

  18. The use of a 18 O tracer and Rutherford backscattering spectrometry to study the oxidation mechanism of NiAl.

    NARCIS (Netherlands)

    Young, E.W.A.; Wit, J.H.W. De

    1985-01-01

    The oxidation mechanism of NiAl was investigated in the temperature range between 1170 K and 1420 K. Oxidation was performed by alternating exposure of the samples to natural oxygen and oxygen gas enriched with 18O. The 18O tracer was profiled by using the reaction with 800 keV protons, 18O(p,α)15N.

  19. Gamow-Teller transitions from 24Mg and its impact on the electron capture rates in the O + Ne + Mg cores of stars

    CERN Document Server

    Nabi, Jameel-Un; 10.1103/PhysRevC.75.035803

    2011-01-01

    Electron captures on nuclei play an important role in the collapse of stellar core in the stages leading to a type-II supernova. Recent observations of subluminous Type II-P supernovae (e.g. 2005cs, 2003gd, 1999br) were able to rekindle the interest in 8 - 10 which develop O+Ne+Mg cores. We used the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory to calculate the B(GT) strength for 24Mg \\rightarrow 24Na and its associated electron capture rates for incorporation in simulation calculations. The calculated rates, in this letter, have differences with the earlier reported shell model and Fuller, Fowler, Newman (hereafter F2N) rates. We compared Gamow-Teller strength distribution functions and found fairly good agreement with experiment and shell model. However, the GT centroid and the total GT strength, which are useful in the calculation of electron capture rates in the core of massive pre-supernova stars, lead to the enhancement of our rate up to a factor of four compared to the shell ...

  20. Clustering effects in fusion evaporation reactions with light even-even N=Z nuclei. The 24Mg and 28Si cases

    Science.gov (United States)

    Morelli, L.; Bruno, M.; D'Agostino, M.; Baiocco, G.; Gulminelli, F.; Cinausero, M.; Degerlier, M.; Fabris, D.; Gramegna, F.; Marchi, T.; Barlini, S.; Bini, M.; Casini, G.; Gelli, N.; Pasquali, G.; Piantelli, S.; Valdrè, S.

    2016-06-01

    In the recent years, cluster structures have been evidenced in many ground and excited states of light nuclei [1, 2]. The decay of highly excited states of 24Mg is studied in fusion evaporation events completely detected in charge in the reactions 12C+12C and 14N+10B at 95 and 80 MeV incident energy, respectively, and compared to the results of a pure statistical model [3, 4]. Inclusive variables are in general well reproduced by the model. We found clear deviations from the statistical model if we select emission channels involving multiple α particles which are more probable than expected from a purely statistical behavior. Data from 12C+12C reaction have been analyzed in order to study the decay of the Hoyle state of 12C* with two different selections: peripheral binary collisions and 6α decay channel in central events. To continue the investigation on light systems, we have recently measured the 16O+12C reaction at three different beam energies, namely Ebeam = 90, 110 and 130 MeV. Preliminary results are presented.

  1. Calibration of speleothem δ18O records against hydroclimate instrumental records in Central Brazil

    Science.gov (United States)

    Moquet, J. S.; Cruz, F. W.; Novello, V. F.; Stríkis, N. M.; Deininger, M.; Karmann, I.; Santos, R. Ventura; Millo, C.; Apaestegui, J.; Guyot, J.-L.; Siffedine, A.; Vuille, M.; Cheng, H.; Edwards, R. L.; Santini, W.

    2016-04-01

    δ18O in speleothems is a powerful proxy for reconstruction of precipitation patterns in tropical and sub-tropical regions. The aim of this study is to calibrate the δ18O record of speleothems against historical precipitation and river discharge data in central Brazil, a region directly influenced by the Southern Atlantic Convergence Zone (SACZ), a major feature of the South American Monsoon System (SAMS). The present work is based on a sub-annual resolution speleothem record covering the last 141 years (the period between the years 1870 and 2011) from a cave in central Brazil. The comparison of this record with instrumental hydroclimate records since 1921 allows defining a strong relationship between precipitation variability and stable oxygen isotope ratios from speleothems. The results from a monitoring program of climatic parameters and isotopic composition of rainfall and cave seepage waters performed in the same cave, show that the rain δ18O variability is dominated by the amount effect in this region, while δ18O drip water remains almost constant over the monitored period (1.5 years). The δ18O of modern calcite, on the other hand, shows clear seasonal variations, with more negative values observed during the rainy season, which implies that other factors also influence the isotopic composition of carbonate. However, the relationship between δ18O of carbonate deposits and rainwater is supported by the results from the comparison between speleothem δ18O records and historical hydroclimate records. A significant correlation between speleothem δ18O and monsoon rainfall variability is observed on sub-decadal time scales, especially for the monsoon period (DJFM and NDJFM), once the rainfall record have been smoothed with a 7-9 years running mean. This study confirms that speleothem δ18O is directly associated with monsoon rainfall variability in central Brazil. The relationship between speleothem δ18O records and hydroclimatic historical records allows

  2. Coherency of late Holocene European speleothem δ18O records linked to North Atlantic Ocean circulation

    Science.gov (United States)

    Deininger, Michael; McDermott, Frank; Mudelsee, Manfred; Werner, Martin; Frank, Norbert; Mangini, Augusto

    2016-09-01

    Speleothem δ18O records provide valuable information about past continental environmental and climatic conditions, although their interpretation is often not straightforward. Here we evaluate a compilation of late Holocene speleothem δ18O records using a Monte Carlo based Principal Component Analysis (MC-PCA) method that accounts for uncertainties in individual speleothem age models and for the variable temporal resolution of each δ18O record. The MC-PCA approach permits not only the identification of temporally coherent changes in speleothem δ18O; it also facilitates their graphical depiction and evaluation of their spatial coherency. The MC-PCA method was applied to 11 Holocene speleothem δ18O records that span most of the European continent (apart from the circum-Mediterranean region). We observe a common (shared) mode of speleothem δ18O variability that suggests millennial-scale coherency and cyclicity during the last 4.5 ka. These changes are likely caused by variability in atmospheric circulation akin to that associated with the North Atlantic Oscillation, reflecting meridionally shifted westerlies. We argue that these common large-scale variations in European speleothem δ18O records are in phase with changes in the North Atlantic Ocean circulation indicated by the vigour of the Iceland Scotland Overflow Water (ISOW), the strength of the subpolar gyre (SPG) and an ocean stacked North Atlantic ice rafted debris (IRD) index. Based on a recent modelling study, we conclude that these changes in the North Atlantic circulation history may be caused by wind stress on the ocean surface driven by shifted westerlies. However, the mechanisms that ultimately force the westerlies remain unclear.

  3. The "Flood of the Century" as Isotopic Fingerprint in Canopy d18O Signatures

    Science.gov (United States)

    Seibt, U.; Wingate, L.; Berry, J. A.

    2006-12-01

    The d18O composition of water and CO2 exchange at smaller scales (leaf and ecosystem) can be affected by changes in environmental conditions at larger (regional) scales. During a sampling campaign in a beech forest in Germany in August 2002, we encountered such a large scale change when dry sunny weather was followed by a large storm system with heavy rains leading to floods across Europe. During the first, sunny period, bulk leaf water d18O was -1 permil at night and 7 permil at mid-day. Foliage CO2 exchange had positive values of 18O discrimination during photosynthesis (10-30 permil) and nocturnal respiration (11 permil). The second period had frequent rains and mostly diffuse light, with reduced foliage water fluxes but similar carbon fluxes. Canopy vapour d18O decreased at least 2 permil, and leaf water then reflected isotopic exchange with this depleted vapour due to the high humidity. Hence, bulk leaf water was substantially more depleted at night (-8 permil) and showed virtually no evaporative enrichment during the day (-5 permil). Values of 18O discrimination during CO2 exchange were small or even negative for photosynthesis (-2 to 6 permil) but larger for nocturnal respiration (23-39 permil). Model simulations indicated that the small positive foliage isoflux during the day was offset by the negative isoflux at night. As a consequence, the d18O of CO2 in canopy air decreased from -0.3 permil during the sunny period to -3 permil during the wet period. The d18O signatures of canopy water and CO2 thus reflected the transition from local water to the regional regime of depleted water deposited across the area by the storm.

  4. Variational features of precipitation δ18O in Northeast Qinghai-Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    章新平; 施雅风; 姚檀栋

    1995-01-01

    There is a marked positive correlation between δ18O in atmospheric precipitation andtemperature in the Northeast Qinghai-Tihet Plateau.The amount effect in Tuotuohe station is notable as thetemperature is greater than or equal to 7.3℃,so is in Xining as 8.3℃.The analytic results show that thesynoptic and climatic significance of different time scales is different,and their degrees are also different.Moreover,the relations between the weather systems in the Northeast Qinghai-Tibet Plateau and δ18O inprecipitation are analyzed.Under the influence of continental air mass the δ18O change in the Plateau issynchronous with that of temperature and under the oceanic air mass originated from the Bengal Bay and theArabian Sea there is a marked negative correlation between δ18O and precipitation amount or temperature in themonsoon region of the Plateau and also positive one between δ18O and temperature in the non-monsoon region.

  5. Experimental study of the 18O(d, p)19O reaction and the ANC Method

    International Nuclear Information System (INIS)

    The neutron capture rate 18O(n, γ)19O is important for analysis of nucleosynthesis in inhomogeneous Big Bang models and also for models of helium burning in massive red giant stars and AGB stars. Angular distributions of the 18O(d, p)19O reaction were measured at a deuteron energy of 16.3 MeV in NPI in Rez, Czech Republic, with the aim to determine Asymptotic Normalization Coefficients which can then be used for indirect determination of the direct contribution to the 18O(n, γ)19O process. In the experiment, the gas target with 18O isotope of high purity 99.9% was used thus eliminating any contaminating reactions. Reaction products were measured by the set of 8 ΔE-E telescopes consisting of thin and thick silicon surface-barrier detectors. Angular distributions of proton transfers corresponding to 6 levels of 19O up to the 4.1093 MeV excitation energy were determined. The analysis of angular distributions in the angular range from 6 to 64 degree including also the angular distribution of elastically scattered deuterons was carried out by means of ECIS and DWUCK codes. From the determined ANCs the direct contribution to the radiative capture 18O(n, γ)19O was deduced.

  6. Leaching studies of soda-lime-silica glass using deuterium- and 18O-enriched solutions

    International Nuclear Information System (INIS)

    With a glass of composition (in mol%) 74 SiO2,16 NaO, 10 CaO, various leaching experiments were conducted, in which besides solutions of normal isotopic composition deuterium- and 18O-enriched solutions were used. The concentration profiles of deuterium, hydrogen, and 18O in the sample were measured with nuclear analyzing techniques. A distinct H/D isotope effect was observed, showing that hydrogen takes part in the rate-determining step of leaching. The measured ratio of 18O uptake to hydrogen uptake during leaching gives evidence for exchange of oxygen between the glas network and water molecules contained in the leached layer. From measurements on the exchange of hydrogen and oxygen between solution and leached layer, a high mobility of water molecules in the leached layer and evidence for condensation of silanol groups was found. (orig.)

  7. Variations of δ18O in Precipitation along Vapor Transport Paths

    Institute of Scientific and Technical Information of China (English)

    章新平; 刘晶淼; 田立德; 何元庆; 姚檀栋

    2004-01-01

    Three sampling cross sections along the south path starting from the Tropics through the vapor passage in the Yunnan-Guizhou Plateau to the middle-low reaches of the Yangtze River, the north path from West China, via North China, to Japan under the westerlies, and the plateau path from South Asia over the Himalayas to the northern Tibetan Plateau, are set up, based on the IAEA (International Atomic Energy Agency)/WMO global survey network and sampling sites on the Tibetan Plateau. The variations, and the relationship with precipitation and temperature, of the δ18O in precipitation along the three cross sections are analyzed and compared. Along the south path, the seasonal differences of mean δ18O in precipitation are small at the stations located in the Tropics, but increase markedly from Bangkok towards the north, with the δ18O in the rainy season smaller than inthe dry season. The δ18O values in precipitation fluctuate on the whole, which shows that there are different vapor sources. Along the north path, the seasonal differences of the mean δ18O in precipitation for the stations in the west of Zhengzhou are all greater than in the east of Zhengzhou. During the cold half of the year, the mean δ18O in precipitation reaches its minimum at Urumqi with the lowest temperature due to the wide, cold high pressure over Mongolia, then increases gradually with longitude, and remains at roughly the same level at the stations eastward from Zhengzhou. During the warm half of the year, the δ18O values in precipitation are lower in the east than in the west, markedly influenced by the summer monsoon over East Asia. Along the plateau path, the mean δ18O values in precipitation in the rainy season are correspondingly high in the southern parts of the Indian subcontinent, and then decrease gradually with latitude. A sharp depletion of the stable isotopic compositions in precipitation takes place due to the very strong rainout of the stable isotopic compositions in vapor in

  8. French summer droughts since 1326 AD: a reconstruction based on tree ring cellulose δ18O

    Directory of Open Access Journals (Sweden)

    I. Labuhn

    2015-11-01

    Full Text Available The reconstruction of droughts is essential for the understanding of past drought dynamics, and can help evaluate future drought scenarios in a changing climate. This article presents a reconstruction of summer droughts in France based on annually resolved, absolutely dated chronologies of oxygen isotope ratios (δ18O in tree ring cellulose from Quercus spp. Samples were taken from living trees and timber wood from historic buildings at two sites: Fontainebleau (48° 23' N, 2° 40' E; 1326–2000 AD and Angoulême (45° 44' N, 0° 18' E; 1360–2004 AD. Cellulose δ18O from these sites proved to be a good proxy of summer climate, as the trees were sensitive to temperature and moisture availability. However, offsets in average δ18O values between tree cohorts necessitated a correction before joining them to the final chronologies. Using the corrected δ18O chronologies, we developed models based on linear regression to reconstruct drought, expressed by the standardized precipitation evapotranspiration index (SPEI. The significant correlations between the SPEI and cellulose δ18O (r ≈ −0.70, as well as the verification of the models by independent data support the validity of these reconstructions. At both sites, recent decades are characterized by increasing drought. Fontainebleau displays dominantly wetter conditions during earlier centuries, whereas the current drought intensity is not unprecedented in the Angoulême record. While the δ18O chronologies at the two studied sites are highly correlated during the 19th and 20th century, there is a significant decrease in the correlation coefficient between 1550 and 1800 AD, which indicates either a weaker climate sensitivity of the tree ring proxies during this period, or a more heterogeneous climate in the north and the south of France. Future studies of tree ring isotope networks might reveal if the seasonality and spatial patterns of past droughts can explain this decoupling.

  9. French summer droughts since 1326 AD: a reconstruction based on tree ring cellulose δ18O

    Science.gov (United States)

    Labuhn, I.; Daux, V.; Girardclos, O.; Stievenard, M.; Pierre, M.; Masson-Delmotte, V.

    2015-11-01

    The reconstruction of droughts is essential for the understanding of past drought dynamics, and can help evaluate future drought scenarios in a changing climate. This article presents a reconstruction of summer droughts in France based on annually resolved, absolutely dated chronologies of oxygen isotope ratios (δ18O) in tree ring cellulose from Quercus spp. Samples were taken from living trees and timber wood from historic buildings at two sites: Fontainebleau (48° 23' N, 2° 40' E; 1326-2000 AD) and Angoulême (45° 44' N, 0° 18' E; 1360-2004 AD). Cellulose δ18O from these sites proved to be a good proxy of summer climate, as the trees were sensitive to temperature and moisture availability. However, offsets in average δ18O values between tree cohorts necessitated a correction before joining them to the final chronologies. Using the corrected δ18O chronologies, we developed models based on linear regression to reconstruct drought, expressed by the standardized precipitation evapotranspiration index (SPEI). The significant correlations between the SPEI and cellulose δ18O (r ≈ -0.70), as well as the verification of the models by independent data support the validity of these reconstructions. At both sites, recent decades are characterized by increasing drought. Fontainebleau displays dominantly wetter conditions during earlier centuries, whereas the current drought intensity is not unprecedented in the Angoulême record. While the δ18O chronologies at the two studied sites are highly correlated during the 19th and 20th century, there is a significant decrease in the correlation coefficient between 1550 and 1800 AD, which indicates either a weaker climate sensitivity of the tree ring proxies during this period, or a more heterogeneous climate in the north and the south of France. Future studies of tree ring isotope networks might reveal if the seasonality and spatial patterns of past droughts can explain this decoupling.

  10. Separating Long-Lived Metal Ions from 18F During H2 18O Recovery

    International Nuclear Information System (INIS)

    Cyclotron targets for the production of [18F]fluoride usually use a thin metal window to contain the 18O enriched water during irradiation. This window is activated by the proton beam, and undesired radioisotopes can enter the target water. A pre-packaged strong anion exchange resin is commonly used for [18O]-water recovery. A two-column method has been developed which delivers >95% of the [18F]fluoride for radiosynthesis while rejecting >99.9% of the contaminants. (author)

  11. Generalized hyperspheric function method and the pion scattering by nucleus of 18O

    International Nuclear Information System (INIS)

    In the framework of the known multiple scattering theory the differential cross section of the 18Q(PI, PI) reaction for the energies 29, 164, 180 and 230 MeV is calculated. The wave functions of the ground state and excited states of the nucleus 18O are found in the minimum approach of generalized hyperspheric function method. The pion-nucleus t sub(PIA) matrix is constructed by solving the Lippman-Schwinger equation on-energy-shell and taken into account the phases of PIN - scattering. Theoretical values of oifferential cross section of the (PI+- - 18O)-reaction under consideration adequately describe experimental data

  12. ({sup 18}O,{sup 18}Ne) double charge-exchange with MAGNEX

    Energy Technology Data Exchange (ETDEWEB)

    Bondí, M.; Cappuzzello, F.; Nicolosi, D.; Tropea, S. [Dipartimento di Fisica e Astrofisica, Universitá degli studi di Catania, Catania, 95100, Italy and Istituto di Fisica Nucleare - Laboratori Nazionali del Sud, Catania, 95100 (Italy); Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A. [Istituto di Fisica Nucleare - Laboratori Nazionali del Sud, Catania, 95100 (Italy); De Napoli, M.; Foti, A. [Istituto di Fisica Nucleare - Sezione di Catania, Catania, 95100 (Italy)

    2014-05-09

    An experimental study concerning Double Gamow-Teller (DGT) modes in ({sup 18}O,{sup 18}Ne) Double Charge-Exchange reactions has been very recently performed at INFN-LNS laboratory in Catania. The experiment was performed using a {sup 40}Ca solid target and a {sup 18}O Cyclotron beam at 270 MeV incident energy. Charged ejectiles produced in the reaction were momentum analyzed and identified by MAGNEX spectrometer at very forward angles. Preliminary results are presented in the present paper.

  13. Evidence of Suess solar-cycle bursts in Holocene speleothem d18O records

    DEFF Research Database (Denmark)

    Knudsen, Mads Faurschou; Jacobsen, B. H.; Riisager, Peter;

    2012-01-01

    subtropical speleothem δ18O records, which allows a strong test of the link between solar activity, monsoon activity (or intensity), and the hydrological cycle. This is possible because the speleothem δ18O records mainly reflect changes in local rainfall composition, which is controlled by changes in total...... driving centennial-scale changes in the hydrological cycle in the subtropics during the Holocene.......Several studies indicate that changes in solar activity may have driven Holocene subtropical monsoon variability on decadal and centennial timescales, but the strength and nature of this link remains debated. In this study, we combine a recent mapping of the Holocene solar-cycle activity with four...

  14. Excitation Function for the 74Se(18O,p3n) Reaction

    OpenAIRE

    Gates, Jacklyn

    2009-01-01

    The 74Se(18O,p3n)88gNb excitation function was measured and a maximum cross section of 495+-5 mb was observed at and 18O energy of 74.0 MeV. Experimental cross sections were compared to theoretical calculations using the computer code ALICE-91 and the values were found to be in good agreement. The half life of 88gNb was determined to be around 14.56+-0.11 min.

  15. Millennial-length forward models and pseudoproxies of stalagmite δ18O: an example from NW Scotland

    Directory of Open Access Journals (Sweden)

    C. Spötl

    2012-07-01

    Full Text Available The stable oxygen isotope parameter δ18O remains the most widely utilised speleothem proxy for past climate reconstructions. Uncertainty can be introduced into stalagmite δ18O from a number of factors, one of which is the heterogeneity of groundwater flow in karstified aquifers. Here, we present a lumped parameter hydrological model, KarstFor, which is capable of generating monthly simulations of surface water – ground water – stalagmite δ18O for more than thousand-year time periods. Using a variety of climate input series, we use this model for the first time to compare observational with modelled (pseudoproxy stalagmite δ18O series for a site at Assynt, NW Scotland, where our knowledge of δ18O systematics is relatively well understood. The use of forward modelling allows us to quantify the relative contributions of climate, peat and karst hydrology, and disequilibrium effects in stalagmite δ18O, from which we can identify potential stalagmite δ18O responses to climate variability. Comparison of the modelled and actual stalagmite δ18O for two stalagmites from the site demonstrates that, for the period of overlapping growth, the two series do not correlate with one another, but forward modelling demonstrates that this falls within the range explicable by differences in flow routing to the stalagmites. Pseudoproxy δ18O stalagmite series highlight the potential significance of peat hydrology in controlling stalagmite δ18O over the last 1000 yr at this site.

  16. Millennial-length forward models and pseudoproxies of stalagmite δ18O: an example from NW Scotland

    Directory of Open Access Journals (Sweden)

    C. Spötl

    2012-03-01

    Full Text Available The stable oxygen isotope parameter δ18O remains the most widely utilised speleothem proxy for past climate reconstructions. Uncertainty can be introduced into stalagmite δ18O from a number of factors, one of which is the heterogeneity of groundwater flow in karstified aquifers. Here, we present a lumped parameter hydrological model, KarstFor, which is capable of generating monthly simulations of surface water – ground water – stalagmite δ18O for more than thousand year time periods. Using a variety of climate input series, we use this model for the first time to compare observational with modelled (pseudoproxy stalagmite δ18O series for a site at Assynt, NW Scotland, where our knowledge of δ18O systematics is relatively well understood. The use of forward modelling allows us to quantify the relative contributions of climate, peat and karst hydrology, and disequilibrium effects in stalagmite δ18O, from which we can identify potential stalagmite δ18O responses to climate variability. Comparison of the modelled and actual stalagmite δ18O for two stalagmites from the site demonstrates that for the period of overlapping growth, the two series do not correlate with one another, but forward modelling demonstrates that this falls within the range explicable by differences in flow routing to the stalagmites. Pseudoproxy δ18O stalagmite series highlight the potential significance of peat hydrology in controlling stalagmite δ18O over the last 1000 years at this site.

  17. Fusion Reactions of ~(16)O+~(76)Ge and ~(18)O+~(74)Ge Near Coulomb Barrier

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The fusion excitation functions of 16O+76Ge and 18O+74Ge at near-barrier region are measured, to research the positive Q-2n effect on the fusion reaction. The properties of the lower excited states are similar for the two targets. For neutron transfer channels,

  18. Reef coral δ18O thermometer in Hainan island waters, south China sea

    International Nuclear Information System (INIS)

    An 18-year-long (1981-1998) study was conducted in Hainan Island waters (22 degree 22'N, 110 degree 39'E) to determine the relationship between δ18O in skeletal aragonite carbonate and sea surface temperature (SST) in porites lutea of reef-building corals. δ18O values in skeletal aragonite carbonate were measured by means of mass spectrometry. Coral samples grew at 5 m depth at Longwan Bay. Monthly measurements of the SST from 1960 to 1998 were taken at Qinglan Bay adjacent to the place of the collected samples. The thermometer shows that SST = -4.16 δ18OPDB + 4.9 (r = 0.80) and dδ18O/dT = -0.24 per mil/degree C. The δ18O thermometer is strongly influenced by the rainfall and runoff. Using the thermometer, the SST in the past hundred years with monthly resolution will be reconstructed and the climatic change in the northern area of South China Sea will be hind cast

  19. Holocene record of precipitation seasonality from lake calcite δ18O in the central Rocky Mountains, United States

    Science.gov (United States)

    Anderson, Lesleigh

    2011-01-01

    A context for recent hydroclimatic extremes and variability is provided by a ~10 k.y. sediment carbonate oxygen isotope (??18O) record at 5-100 yr resolution from Bison Lake, 3255 m above sea level, in northwestern Colorado (United States). Winter precipitation is the primary water source for the alpine headwater lake in the Upper Colorado River Basin and lake water ??18O measurements reflect seasonal variations in precipitation ??18O. Holocene lake water ??18O variations are inferred from endogenic sedimentary calcite ??18O based on comparisons with historic watershed discharge records and tree-ring reconstructions. Drought periods (i.e., drier winters and/or a more rain-dominated seasonal precipitation balance) generally correspond with higher calcite ??18O values, and vice-versa. Early to middle Holocene ??18O values are higher, implying a rain-dominated seasonal precipitation balance. Lower, more variable ??18O values after ca. 3500 yr ago indicate a snow-dominated but more seasonally variable precipitation balance. The middle to late Holocene ??18O record corresponds with records of El Ni??o Southern Oscillation intensification that supports a teleconnection between Rocky Mountain climate and North Pacific sea-surface temperatures at decade to century time scales. ?? 2011 Geological Society of America.

  20. Evidence for a universal pathway of abscisic acid biosynthesis in higher plants from sup 18 O incorporation patterns

    Energy Technology Data Exchange (ETDEWEB)

    Zeevaart, J.A.D.; Heath, T.G.; Gage, D.A. (Michigan State University, East Lansing (USA))

    1989-12-01

    Previous labeling studies of abscisic acid (ABA) with {sup 18}O{sub 2} have been mainly conducted with water-stressed leaves. In this study, {sup 18}O incorporation into ABA of stressed leaves of various species was compared with {sup 18}O labeling of ABA of turgid leaves and of fruit tissue in different stages of ripening. In stressed leaves of all six species investigated, avocado (Persea americana), barley (Hordeum vulgare), bean (Phaseolus vulgaris), cocklebur (Xanthium strumarium), spinach (Spinacia oleracea), and tobacco (Nicotiana tabacum), {sup 18}O was most abundant in the carboxyl group, whereas incorporation of a second and third {sup 18}O in the oxygen atoms on the ring of ABA was much less prominent after 24 h in {sup 18}O{sub 2}. ABA from turgid bean leaves showed significant {sup 18}O incorporation, again with highest {sup 18}O enrichment in the carboxyl group. On the basis of {sup 18}O-labeling patterns observed in ABA from different tissues it is concluded that, despite variations in precusor pool sizes and intermediate turnover rates, there is a universal pathway of ABA biosynthesis in higher plants which involves cleavage of a larger precursor molecule, presumably an oxygenated carotenoid.

  1. Evidence for a universal pathway of abscisic acid biosynthesis in higher plants from 18O incorporation patterns

    International Nuclear Information System (INIS)

    Previous labeling studies of abscisic acid (ABA) with 18O2 have been mainly conducted with water-stressed leaves. In this study, 18O incorporation into ABA of stressed leaves of various species was compared with 18O labeling of ABA of turgid leaves and of fruit tissue in different stages of ripening. In stressed leaves of all six species investigated, avocado (Persea americana), barley (Hordeum vulgare), bean (Phaseolus vulgaris), cocklebur (Xanthium strumarium), spinach (Spinacia oleracea), and tobacco (Nicotiana tabacum), 18O was most abundant in the carboxyl group, whereas incorporation of a second and third 18O in the oxygen atoms on the ring of ABA was much less prominent after 24 h in 18O2. ABA from turgid bean leaves showed significant 18O incorporation, again with highest 18O enrichment in the carboxyl group. On the basis of 18O-labeling patterns observed in ABA from different tissues it is concluded that, despite variations in precusor pool sizes and intermediate turnover rates, there is a universal pathway of ABA biosynthesis in higher plants which involves cleavage of a larger precursor molecule, presumably an oxygenated carotenoid

  2. Late Holocene hydroclimate change inferred from δ18O of lake sediments, Lost River Range, Idaho

    Science.gov (United States)

    Krueger, C. R.; Finney, B. P.; Shapley, M.

    2012-12-01

    High-resolution paleohydrological records are needed to assess the frequency and magnitude of past droughts in Idaho and the northern Rocky Mountain region, but are scarce in this semi-arid region. Sediments from Lost Keys Pond (LKP) can be used to reconstruct hydroclimate. LKP is closed to surface outflow and is therefore sensitive to precipitation minus evaporation; surface water is enriched in δ18O compared to the local meteoric waters. In summer 2011 several sediment cores were collected from LKP using a square rod piston corer; the focus of this analysis is an 82-cm Bolivia core. This core contains thinly banded to laminated, authigenic carbonate mud, a recorder of lake δ18O at the time of deposition. This core was sampled for δ18O and /δ13C at 0.5 cm intervals, and the <20 um fraction was isolated to avoid any detrital carbonate. Based on the current age model, sampling at this interval records sub-decadal (5-10 year) hydroclimate variability. The δ18O signal recovered has 5‰ variability over the length of the record, including several major fluctuations in last 1,000 years. During this period, several major dry and wet periods have been recorded occurring over multidecadal timescales, with a trend toward increasing aridity. The δ18O and δ13C records in the lowest decimeter are divergent and mirror each other, above this interval isotopic records have strong covariance. This pattern may be indicative of a change from surface outflow to no surface outflow conditions. The age model is being refined to better assess how this record correlates with other regional records, and ultimately improve our understanding of past atmospheric circulation.

  3. 13C-18O bonding (Δ47) in deep-sea corals: a calibration study

    Science.gov (United States)

    Kimball, J. B.; Tripati, A.; Dunbar, R. B.; Eagle, R.

    2013-12-01

    Deep-sea corals are a potentially valuable archive of temperature in intermediate and deep waters, regions for which a paucity of temperature data exists. These archives could give valuable insight into the natural variability of areas of the ocean that play an active role in large-scale climate dynamics. Due to significant 'vital effects' (i.e., non-equilibrium mineral compositions) in δ18O, however, deep-sea coral have been challenging to develop as a paleotemperature proxy. Clumped-isotope paleothermometry is a new method that may circumvent some of the known complications with δ18O paleotemperature analysis in deep-sea coral. This geothermometer is based on the ordering of heavy 13C-18O ';clumps' in carbonate minerals. Initial calibration studies have shown that the method is independent from the solution chemistry of the precipitating fluids as well as 'vital effects' in deep-sea corals and other types of carbonates. Some kinetic effects have been observed in tropical corals and speleothems. Here we report new data in order to further develop clumped isotopes as a paleothermometer in deep-sea corals as well as to investigate taxon-specific effects. 13C-18O bond ordering was analyzed in live-collected scleractinian (Enallopsammia sp.) and gorgonian (Isididae and Coralliidae) deep-sea corals. We determined mass 47 anomalies in samples (Δ47), which refers to the parts per thousand excess of 13C-18O-16O in CO2 produced on acid digestion of a sample, relative to the amount predicted to be present if isotopes were randomly distributed amongst all CO2 isotopologues. Measured Δ47 values were compared to in situ temperatures and the relationship between Δ47 and temperature was determined for each group to investigate taxon-specific effects.

  4. Modeling the climatic implications of the Guliya δ18O record during the past 130 ka

    Directory of Open Access Journals (Sweden)

    X. Zhou

    2012-05-01

    Full Text Available Using an intermediate-complexity UVic Earth System Climate Model (UVic Model, the geographical and seasonal implications and an indicative sense of the historical climate found in the δ18O record of the Guliya ice core (hereinafter, the Guliya δ18O are investigated under time-dependent orbital forcing with an acceleration factor of 100 over the past 130 ka. The results reveal that the simulated late-summer (August–September Guliya surface air temperature (SAT reproduces the 23-ka precession and 43-ka obliquity cycles in the Guliya δ18O. Furthermore, the Guliya δ18O is significantly correlated with the SAT over the Northern Hemisphere (NH, which suggests the Guliya δ18O is an indicator of the late-summer SAT in the NH. Corresponding to the warm and cold phases of the precession cycle in the Guliya temperature, there are two anomalous patterns in the SAT and sea surface temperature (SST fields. The first anomalous pattern shows an increase in the SAT (SST toward the Arctic, possibly associated with the joint effect of the precession and obliquity cycles, and the second anomalous pattern shows an increase in the SAT (SST toward the equator, possibly due to the influence of the precession cycle. Additionally, the summer (winter Guliya and NH temperatures are higher (lower in the warm phases of Guliya late-summer SAT than in the cold phases. Furthermore, the Guliya SAT is closely related to the North Atlantic SST, in which the Guliya precipitation may act as a "bridge" linking the Guliya SAT and the North Atlantic SST.

  5. Coherency of European speleothem δ18O records linked to North Atlantic ocean circulation

    Science.gov (United States)

    Deininger, Michael; McDermott, Frank

    2016-04-01

    Speleothem δ18O records can provide valuable information about past continental environmental and climatic conditions. In recent decades a European speleothem network has been assembled that allows us to reconstruct past climate variability in both space and time. In particular climate variability during the Holocene was investigated by these studies. The Holocene is thus an ideal period to apply sophisticated statistical methods to derive spatio-temporal pattern of common climate variability in the European speleothem record. Here we evaluate a compilation of 10 speleothem δ18O records covering the last 4.5 ka for their shared variability. The selected speleothem δ18O records must satisfy certain quality criteria to be included: (i) a robust age model; (ii) a temporal intra-sampling resolution of smaller than 30 years; and (iii) the record should be published. A Monte Carlo based Principal Component Analysis (MC-PCA) that accounts for uncertainties in individual speleothem age models and for the different and varying temporal resolutions of each speleothem δ18O record was used for this purpose. Our MC-PCA approach allows not only the identification of temporally coherent changes in δ18O records, but it also facilitates their depiction and evaluation spatially. The compiled speleothem δ18O records span almost the entire European continent (with the exception of the circum-Mediterranean region) ranging from the western Margin of the European continent (stalagmite CC-3, Ireland) to Northern Turkey (SO-1) and from Northern Italy (CC-26) to Norway (FM-3). For the MC-PCA analysis, the 4.5 ka period was sub-divided into eight 1 ka long time windows that overlap the subsequent time window by 500 years to allow a comparison of the temporal evolution of the common signal. In this study we only interpreted the 1st principal component (PC) that depict the spatio-temporal pattern with the highest explained variability of all speleothem δ18O records. Our MC-PCA results

  6. Study of the angular correlations of light charged particles for the reaction {sup 35}CI (260 MeV) + {sup 24}Mg; Etude des correlations angulaires de particules legeres chargees dans la reaction {sup 35}CI (260 MeV) + {sup 24}Mg

    Energy Technology Data Exchange (ETDEWEB)

    Mahboub, D.

    1996-10-30

    This work is focussed on the investigation of deformed nuclei. The asymmetric fusion-fission of light heavy-ions (A {<=}60) with a high excitation energy (T {approx} 4 MeV) had lead to a large deformation of the compound nucleus at the scission point. The angular correlations between light particles (LP) and their emitting fragments has been used to probe the deformation of nucleus. Exclusive measurements were performed for the {sup 35}Cl (260 MeV) + {sup 24}Mg system leading to the {sup 59}Cu compound nucleus (CN). The comparison between the energy spectra of LP`s and a statistical calculation carried out by a Monte-Carlo code CASCADE has suggested a deformation of 1.3 (for an oblate shape) of the CN within the frame work of fusion-evaporation process. The source velocity spectrum of {alpha} particles and angular correlations of LP`s have showed that pre-scission and pre-equilibrium emissions are negligible in the present reaction. Finally the confrontation of the data with the statistical code GEMINI has pointed out the sequential emission character of the LP`s from the fission fragments. (author). 175 refs.

  7. French summer droughts since 1326 CE: a reconstruction based on tree ring cellulose δ18O

    Science.gov (United States)

    Labuhn, Inga; Daux, Valérie; Girardclos, Olivier; Stievenard, Michel; Pierre, Monique; Masson-Delmotte, Valérie

    2016-05-01

    The reconstruction of droughts is essential for the understanding of past drought dynamics and can help evaluate future drought scenarios in a changing climate. This article presents a reconstruction of summer droughts in France based on annually resolved, absolutely dated chronologies of oxygen isotope ratios (δ18O) in tree ring cellulose from Quercus spp. Samples were taken from living trees and timber wood from historic buildings at two sites: Fontainebleau (48°23' N, 2°40' E; 1326-2000 CE) and Angoulême (45°44' N, 0°18' E; 1360-2004 CE). Cellulose δ18O from these sites proved to be a good proxy of summer climate, as the trees were sensitive to temperature and moisture availability. However, offsets in average δ18O values between tree cohorts necessitated a correction before joining them to the final chronologies. Using the corrected δ18O chronologies, we developed models based on linear regression to reconstruct drought, expressed by the standardized precipitation evapotranspiration index (SPEI). The significant correlations between the SPEI and cellulose δ18O (r ≈ -0.70), as well as the verification of the models by independent data support the validity of these reconstructions. At both sites, recent decades are characterized by increasing drought. Fontainebleau displays dominantly wetter conditions during earlier centuries, whereas the current drought intensity is not unprecedented in the Angoulême record. While the δ18O chronologies at the two studied sites are highly correlated during the 19th and 20th centuries, there is a significant decrease in the correlation coefficient between 1600 and 1800 CE, which indicates either a weaker climate sensitivity of the tree ring proxies during this period, or a more heterogeneous climate in the north and the south of France. Future studies of tree ring isotope networks might reveal if the seasonality and spatial patterns of past droughts can explain this decoupling. A regional drought reconstruction

  8. Intraseasonal Variability of δ18O of Precipitation in The Indonesia Maritime Continent

    Science.gov (United States)

    Belgaman, H. A.; Ichiyanagi, K.; Tanoue, M.; Suwarman, R.; Yoshimura, K.; Mori, S.; Yamanaka, M. D.; Kurita, N.; Syamsudin, F.

    2014-12-01

    The Indonesian maritime continent (IMC) consists of many islands in a warm pool of sea water and is located between two great oceans—the Pacific Ocean and Indian Ocean, and two major continents—the Asian and Australian continents. This tropical region also influenced by many regional and local climate and weather phenomenon which causes high spatial and temporal rainfall variability. These factors may produce unique variability of isotopic precipitation. The isotopic content (d18O and dD) in precipitation have been known to have important role for reconstructing the atmospheric circulation, hydrological cycle, and paleoclimate. Using daily data from six observation station across the IMC (Bukit tinggi, Jambi, Denpasar, Makasar, Manado, and Palau Island), the variability of δ18O was explored. Observation times for each station were different. Bukit Tinggi (GAW) was from Jan. 2001 - Mar. 2010, Jambi (JMB) was from Apr. 2001 - Dec. 2005, Denpasar (DPS), Makassar (MKS), Manado (MND) were from Nov. 2002 - Mar. 2010, and Palau Island (PLL) was from Dec. 2001 - May 2007. Daily average value of δ18O were -7.57‰, -5.41‰, -3.15‰, -6.12‰, -5.49‰ and -4.26‰ for GAW, JMB, DPS, MKS, MND and PLL respectively. Daily value of δ18O in GAW has the lowest value compare with the other station was because the location of GAW station located at high altitude. High correlation of variability of δ18O and Madden-Julian Oscillation (MJO) was observed at western part of the IMC (GAW and JMB), and northern part of the IMC (MKS, MND, and PLL), meanwhile δ18O variability at DPS was less correlated with MJO compare with other stations. Preliminary result from Color Moisture Analysis (CMA) model revealed that precipitable water at GAW and JMB stations was mostly occupied by water vapor evaporated from the Indian Ocean. However, precipitable water at other stations was mostly composed of water vapor evaporated from the Java Sea and the Pacific Ocean. These findings indicate

  9. 18O/16O studies of fossil fissure fumaroles from the Valley of Ten Thousand Smokes, Alaska

    Science.gov (United States)

    Holt, Elizabeth Warner; Taylor, Hugh P.

    2001-06-01

    At three sample sites where there are good exposures of the upper 15 m of the 1912 ash-flow sheet in the Valley of Ten Thousand Smokes (VTTS), Alaska, 18O/16O studies indicate that fumarolic activity produced a very wide range of δ18O values (-0.1 to +12.6; n=32) in the groundmass adjacent to fossil fissure fumaroles. This contrasts sharply with the uniformity of δ18O in the groundmass away from fumarolic conduits (δ18O=+5.9 to +7.1; n=7) and in all of the feldspar phenocrysts (δ18O=+6.11 to +7.5 1 for 11 samples from this study and Hildreth 1987), independent of whether these were collected from fossil fumaroles or from unaltered tuff. Only one sample contained feldspars that were even slightly 18O-enriched relative to the others (cloudy plagioclase δ18O=+8.45). and this sample also contained the most 180-enriched groundmass of any of those analyzed (δ18O=+12.6). This preservation of primary magmatic δ18O values in the VTTS feldspar phenocrysts is clearly a consequence of the extremely short time span (i.e., 1912 to ≈1923) of vigorous, high-temperature, fumarolic activity in the 1912 ash-flow sheet. These 18O/l6O systematica are strikingly similar to those discovered in the 2.8-Ma intracaldera Chegem Tuff (Gazis et al. 1996) and in the fossil fumaroles in the outflow sheet of the 0.76 Ma Bishop Tuff (Holt and Taylor 1998), thus confirming that a similar type of fumarolic meteoric-hydro-thermal activity occurred above the zone of intense welding in all three of these ash-flow tuffs. This is particularly important, because it provides a direct linkage between the older tuffs and the actual observations at the VTTS of steam chemistry, water/rock interaction, circulation geometry, flow velocities, and fumarolic temperatures (up to 645°C). The 18O/l6O effects in the VTTS can all be explained in terms of a two-stage history: (a) an early, 10- to 15-year-long, high-temperature (τ;450°C), fumarolic 18O-depletion event (groundmass δ18O=-0.1 to +4.8); and (b) a

  10. Neutron distribution and yield produced by 50 MeV/u 18O-ion on thick targets

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Neutron energy, fluence rate, angular distributions anddose equivalent rate distributions around the thick Be, Cu,Au targets bombarded by 50 MeV/u 18O-ion were measured usinga threshold detector activation method. At the same time, theneutron yields of 18O-ion and the neutron emission rates inthe forward direction were obtained approximately.

  11. ENSO flavors in a tree-ring δ18O record of Tectona grandis from Indonesia

    Directory of Open Access Journals (Sweden)

    K. Schollaen

    2014-10-01

    Full Text Available Indonesia's climate is dominated by the equatorial monsoon system, and has been linked to El Niño–Southern Oscillation (ENSO events that often result in extensive droughts and floods over the Indonesian archipelago. In this study we investigate ENSO-related signals in a tree-ring δ18O record (1900–2007 of Javanese teak. Our results reveal a clear influence of Warm Pool (central Pacific El Niño events on Javanese tree-ring δ18O, and no clear signal of Cold Tongue (eastern Pacific El Niño events. These results are consistent with the distinct impacts of the two ENSO flavors on Javanese precipitation, and illustrate the importance of considering ENSO flavors when interpreting palaeoclimate proxy records in the tropics.

  12. Analysis of a run-off hydrograph by means of natural 18O

    International Nuclear Information System (INIS)

    A deviation of the oxygen isotopic composition in precipitation from the average 18O/l6O in groundwater can be considered to indicate the presence of some 18O tracer. In this way the precipitation component in the discharge of a catchment area can be established. In a small drainage basin (650 ha) the direct peak run-off in the stream channels from a rain storm is shown to consist of rainwater above a slowly increasing base flow. The fast run-off contains two components: (1) overland flow with a time constant of 1 h; (2) a moderately declining component (time constant of 12 h) probably caused by the release of bank storage. From a complex storm it is shown that 87% infiltrates into the soil and the remaining 13% is drained within a few days. (author)

  13. Influence of Carbonic Anhydrase Activity in Terrestrial Vegetation on the 18O Content of Atmospheric CO2

    Science.gov (United States)

    Gillon, Jim; Yakir, Dan

    2001-03-01

    The oxygen-18 (18O) content of atmospheric carbon dioxide (CO2) is an important indicator of CO2 uptake on land. It has generally been assumed that during photosynthesis, oxygen in CO2 reaches isotopic equilibrium with oxygen in 18O-enriched water in leaves. We show, however, large differences in the activity of carbonic anhydrase (which catalyzes CO2 hydration and 18O exchange in leaves) among major plant groups that cause variations in the extent of 18O equilibrium (θeq). A clear distinction in θeq between C3 trees and shrubs, and C4 grasses makes atmospheric C18OO a potentially sensitive indicator to changes in C3 and C4 productivity. We estimate a global mean θeq value of ~0.8, which reasonably reconciles inconsistencies between 18O budgets of atmospheric O2 (Dole effect) and CO2.

  14. Temporal and spatial distributions of δ18O and δ2H in precipitation in Romania

    Science.gov (United States)

    Nagavciuc, Viorica; Bădăluță, Carmen-Andreea; Perșoiu, Aurel

    2015-04-01

    Stable isotope ratios of meteoric water have an important role in climatic, paleoclimatic, hydrological and meteorological studies. While such data are available from most of Europe, so far, in Romania (East Central Europe), no systematic study of the stable isotopic composition of precipitation exists. In this context, the aim of this study is to analyze the isotopic composition of rainwater, its temporal and spatial distribution, the identification of the main factors influencing these variations and the creation of the first map of spatial distribution of stable isotopes in precipitation in Romania. Between March 2012 and March 2014 we have collected monthly samples from 22 stations in Romania, which were subsequently analyzed for their δ18O and δ2H at the Stable Isotopes Laboratory, Stefan cel Mare University, Suceava, Romania. Precipitation in W and NW Romania plot along the GMWL, while those in the East are slightly below it, on an evaporative trend. The LMWL for Romania is defined as δ2H=7,27*δ18O + 6,92. The W-E gradient in the distribution of δ18O and δ2H are less marked than the N-S ones, with local influences dominating in areas of strong evaporation (intramountain basins, rain-shadow areas etc). In SW, and especially in autumn and winter, Meditteranean cyclones carry moisture from the Eastern Mediterranean, the δ18O and δ2H values in precipitation in the area plotting between the GMWL and the Eastern Mediterranean Meteoric Water Line. The isotopic composition of rainwater in Romania correlates well with air temperature, and is influenced to a lesser extent by other factors such as the amount of precipitation, topography configuration, the effect of continentalism and season of the year.

  15. Regional groundwater flow in the Atikokan Research Area : simulation of 18O and 3H distributions

    International Nuclear Information System (INIS)

    AECL is investigating a concept for disposing of nuclear fuel waste deep in plutonic rock of the Canadian Shield. As part of this investigation, we have performed a model simulation of regional groundwater flow in the Atikokan Research Area, a fractured plutonic rock environment of the Canadian Shield, and used the distribution of oxygen-18 (18O) and tritium (3H) in groundwater to test the model. At the first stage of model calibration, groundwater flow was simulated using a three-dimensional finite-element code, MOTIF, in conjunction with a conceptual framework model derived from field geological, geophysical and hydrogeological data. Hydraulic parameters (permeability and porosity) were systematically varied until simulated recharge rates to the water table compared favourably with estimated recharge rates based on stream flow analysis. At the second stage, vertical average linear groundwater velocities from the first stage of the calibration process were combined with conceptualized one-dimensional models of the system to generate depth concentration profiles of 18O and 3H. Recharge-, midline-and discharge area models of both the fracture zones and the rock mass were employed. The simulated profiles formed 'envelopes' around all field 18O and 3H data, indicating that the calibrated velocities used in the model are reasonable. The models demonstrate that the scatter of δ18O and 3H field data from the Atikokan Research Area is consistent with the groundwater flow model predictions and can be explained by the complexity arising from different hydraulic regimes (recharge, midline, discharge) and hydrogeologic environments (fracture zones, rock mass) of the regional flow system. 50 refs., 14 figs., 3 tabs

  16. Degradation of DNA by iron-bleomycin: mechanistic implications of product 18O incorporation

    International Nuclear Information System (INIS)

    Interaction of d(CGCGCG) with Bleomycin (BLM), activated either with Fe(III) and H2O2 or Fe(II), O2 and one electron, results in production of cytosine and a modified oligonucleotide strand (1). Reduction of 1 with NaBD4 followed by enzymatic digestion, derivatization, and GC-MS permits the identification of 2-deoxypentitols-1,4-d2 as their tetra-trimethylsilyl (TMS) derivatives. Similar products have also been isolated from calf thymus DNA and poly(dG-dC). These results provide unequivocal evidence for the intermediacy of a 4' ketone, 1' aldehyde modified carbohydrate. An alternate mode of DNA degradation requires additional O2 and leads to formation of 3' phosphoglycolate termini and base propenals. Glycolate (GA), released from calf thymus DNA, poly(dA-dT) or d(CGCGCG) by enzymatic digestion, can be isolated by chromatography on DEAE Sephadex, silylated and analyzed by GC-MS. This analysis, after incubation with Fe(II) x 18O2 x BLM or Fe(III) x H216O2 x BLM plus 18O2, reveals the incorporation of a single atom of 18O at the C-1 position. Pulse-chase experiments demonstrate that it is the excess molecular oxygen and not the O2 required for drug activation that is incorporated into the carboxylate group of 3' phosphoglycolate and provide evidence for the proposed addition of O2 to a C4' carbon radical. Isotopic enrichments of the other products of DNA oxidation, formed in the presence of 18O2 are also being determined

  17. Interference effects between direct and sequential processes in the (18O, 16O reaction

    Directory of Open Access Journals (Sweden)

    Cavallaro M.

    2014-03-01

    Full Text Available The 12C(18O, 16O14C reaction at 84 MeV has been studied at INFN-LNS laboratory using the MAGNEX magnetic spectrometer. High resolution energy spectra and cross-section angular distributions have been measured. DWBA calculations of both direct and sequential transfer to the 14C ground state show the important role of the interference between the two processes to describe the experimental data.

  18. Interference effects between direct and sequential processes in the (18O, 16O) reaction

    OpenAIRE

    Cavallaro M.; Cappuzzello F.; Bondì M.; Carbone D.; Garcia V. N.; Gargano A.; Lenzi S.M.; Lubian J.; Agodi C.; Azaiez F.; De Napoli M.; Foti A.; Franchoo S.; Linares R.; Nicolosi D.

    2014-01-01

    The 12C(18O, 16O)14C reaction at 84 MeV has been studied at INFN-LNS laboratory using the MAGNEX magnetic spectrometer. High resolution energy spectra and cross-section angular distributions have been measured. DWBA calculations of both direct and sequential transfer to the 14C ground state show the important role of the interference between the two processes to describe the experimental data.

  19. Clustering in non-self-conjugate nuclei 10Be and 18O

    International Nuclear Information System (INIS)

    Clustering phenomena in 10Be and 18O were studied by means of resonance elastic scattering of α-particles on 6He and 14C. Excitation functions for α+6He and α+14C were measured and detailed R-matrix analyses of the excitation functions was performed. We compare the experimental results with the predictions of modern theoretical approaches and discuss properties of cluster rotational bands

  20. Determination of the delta(18O/16O)of Water: RSIL Lab Code 489

    Science.gov (United States)

    Revesz, Kinga; Coplen, Tyler

    2008-01-01

    The purpose of the technique described by the Reston Stable Isotope Laboratory (RSIL) lab code 489 is to present a method to determine the delta(180/160), abbreviated as delta-180, of water. This delta-18O measurement of water also is a component of National Water Quality Laboratory (NWQL in USGS) schedules 1142 and 1172. Water samples are loaded into glass sample containers on a vacuum manifold to equilibrate gaseous CO2 at constant temperature (25 deg C) with water samples. After loading water samples on the vacuum manifold, air is evacuated through capillary to avoid evaporation, and CO2 is added. The samples are shaken to increase the equilibration rate of water and CO2. When isotopic equilibrium has been attained, an aliquot of CO2 is extracted sequentially from each sample container, separated from water vapor by means of a dry ice trap, and introduced into a dual-inlet isotope-ratio mass spectrometer (DI-IRMS) for determination of the delta-18O value. There is oxygen isotopic fractionation between water and CO2, but it is constant at constant temperature. The DI-IRMS is a DuPont double-focusing mass spectrometer. It has a double collector. One ion beam passes through a slit in a forward collector and is collected in the rear collector. The other ion beams are collected in the front collector. The instrument is capable of measuring mass/charge (m/z) 44 and 45 or 44 and 46 by changing the ion-accelerating voltage under computer control. The ion beams from these m/z values are as follows: m/z 44=CO2=12C16O16O, m/z 45=CO2=13C16O16O primarily, and m/z 46 = CO2=12C16O18O primarily. The data acquisition and control software calculates delta-18O values.

  1. Factors determining δ13C and δ18O fractionation in aragonitic otoliths of marine fish

    Science.gov (United States)

    Thorrold, Simon R.; Campana, Steven E.; Jones, Cynthia M.; Swart, Peter K.

    1997-07-01

    Fish otoliths are aragonitic accretions located within the inner ear of teleost fish. The acellular nature of otoliths, along with taxon-specific shapes, chronological growth increments, and abundance in the fossil record suggest that the stable isotope chemistry of these structures may be unique recorders of environmental conditions experienced by fish in both modern and ancient water masses. To assess the factors determining δ 13C and δ 18O fractionation in fish otoliths, we reared Atlantic croaker ( Micropogonias undulatus) larvae under controlled environmental conditions. Metabolic effects apparently generated large isotopic disequilibria in the δ 13C values of M. undulatus otoliths. We found evidence of a negative regression between δ 13C- carbonate-δ 13C water (δ 13C) and temperature: δ 13C = -1.78 - 0.18 T °C However, this relationship was aliased to a degree by a positive correlation between δ 13C and somatic growth and otolith precipitation rates. Oxygen isotopes were deposited close to equilibrium with the ambient water. The relationship between temperature and the 18O/ 16O fractionation factor (α) was determined empirically to be: 1000 ln α = 18.56(10 3T K -1) - 32.54 The fractionation factor was not affected by either otolith precipitation or fish growth rates. Reconstruction of water temperature histories should, therefore, be possible from the δ 18O values of M. undulatus otoliths with a precision of 1°C, providing the δ 18O of the ambient water can be estimated.

  2. Delta(18)O characteristics of lichens and their effects on evaporative processes of the subjacent soil.

    Science.gov (United States)

    Hartard, Britta; Máguas, C; Lakatos, M

    2008-03-01

    The study presents first data on the delta(18)O performance of poikilohydrous lichen ground cover, and its potential impact on the isotopic composition of water fluxes arising from subjacent soil layers. As a model organism, the globally distributed lichen Cladina arbuscula was studied under laboratory conditions as well as in the field. During a desiccation experiment, delta(18)O of the lichen's thallus water and of its respired CO(2) became enriched by approximately 7 per thousand and followed a similar enrichment pattern to that expected from homoiohydrous, vascular plants. However, the observed degree of enrichment was lower in comparison to vascular plants due to (i) the lichen's inherent lower evaporative resistances; and (ii) a stronger effect of the more depleted surrounding water vapour. In lichens growing in their natural habitat, this specific pattern may show substantial variations depending on prevailing microclimatic conditions. Within a field study, thallus water delta(18)O of lichens principally proved to become more depleted when close to equilibration with the surroundings. It thereby strongly depended on the absorption of surrounding water vapour. Moreover, the results indicate that lichen mats substantially reduce evaporation rates arising from subjacent soil layers, and may alter the isotopic signal of vapour diffusing away from these layers into more depleted values. PMID:18320432

  3. Finding of Neoproterozoic low-18O igneous rocks in the northern margin of the Dabie orogen

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yongfei; WU Yuanbao; ZHAO Zifu; GONG Bing

    2004-01-01

    @@ It has been one of the most intriguing questions in the earth sciences whether the snowball Earth event is genetically associated with mantle superwelling, supercontinent assemblage and breakup, and rift magmatism during the Neoproterozoic[1-4]. In order to demonstrate the occurrence of significant interaction in energy and matter between the earth's interior and exterior in this period, it is critical to find coeval igneous rocks that contain the signature of surface water and thus form low-18O magma.Several investigations of U-Pb dating and O isotope analysis were carried out for zircons from ultrahigh pressure (UHP) metamorphic rocks in the Dabie-Sulu orogen,east-central China[5-8]. The results indicate that low δ18O zircons have U-Pb ages of 700-800 Ma as dated by either TIMS discordia upper-intercept or SIMS in-situ magmatic core, and the origin of low δ18O water is related to cold paleoclimate during the Sturtian ice age.

  4. Terahertz spectroscopy of N$^{18}$O and isotopic invariant fit of several nitric oxide isotopologs

    CERN Document Server

    Müller, Holger S P; Takahashi, Kazumasa; Tomaru, Kazuko; Matsushima, Fusakazu

    2014-01-01

    A tunable far-infrared laser sideband spectrometer was used to investigate a nitric oxide sample enriched in 18O between 0.99 and 4.75 THz. Regular, electric dipole transitions were recorded between 0.99 and 2.52 THz, while magnetic dipole transitions between the 2Pi(1/2) and 2Pi(3/2) spin-ladders were recorded between 3.71 and 4.75 THz. These data were combined with lower frequency data of N(18)$O (unlabeled atoms refer to (14)N and (16)O, respectively), with rotational data of NO, (15)NO, N(17)O, and (15)N(18)O, and with heterodyne infrared data of NO to be subjected to one isotopic invariant fit. Rotational, fine and hyperfine structure parameters were determined along with vibrational, rotational, and Born-Oppenheimer breakdown corrections. The resulting spectroscopic parameters permit prediction of rotational spectra suitable for the identification of various nitric oxide isotopologs especially in the interstellar medium by means of rotational spectroscopy.

  5. Comparisons on seasonal and annual variations of δ18O in precipitation

    Institute of Scientific and Technical Information of China (English)

    ZHANGXinping; YAOTandong

    2004-01-01

    The spatial and temporal variations of stable oxygen isotope in precipitation on different time scales are analyzed according to the data from the IAEA/WMO stations with long survey series in the Northern Hemisphere. Temperature effect is mainly distributed in mid-high latitudes on seasonal scale except for Bamako and Addisababa stations. The δ18O /temperature slope displays the positive correlation against altitude for most of the statistical stations. Amount effect appears primarily in the region south of 30°N and coastal areas. The δ18O/precipitation slope is indirectly proportional to precipitation amount. For some of the sampling stations at mid-high latitudes where their seasonal distribution of precipitation is contrary to that of temperature, coupled with temperature effect, the amount effect appears synchronistically. Either the temperature effect or the amount effect on seasonal scale, there are positive correlations to a certain extent between the annual weighted mean δ18O and the annual mean temperature for almost all the stations. The correlation between composite δ18O and temperature on spatial scale is much more marked, compared with that of individual station. There is a good agreement between 10-year moving average temperature curves Ⅰ and Ⅱ, with the values of the former all markedly smaller than corresponding ones of the latter, calculated by the monthly mean series group Ⅰ and the annual mean series group Ⅱ, respectively. However, two calculated dδ18O/dT curves display the distinct difference: the variation amplitude of slope series Ⅱ is larger than that of slope series Ⅰ. Both curves had similar ascending trend from the 1960s to the 1970s, and then, their variations display the anti-phase. Moreover, the analyses show that there is negative correlation between slope series Ⅱ and temperature series Ⅱ. However, the status is different for slope series Ⅰ and temperature series Ⅰ. Both series have contrary trend from the

  6. ({sup 18}O,{sup 16}O) Two-neutron transfer reactions for spectroscopic studies

    Energy Technology Data Exchange (ETDEWEB)

    Cavallaro, Manuela; Agodi, Clementina; Bondi, Mariangela; Cappuzzello, Francesco; Carbone, Diana; Cunsolo, Angelo; Foti, Antonino; Napoli, Marzio de; Nicolosi, Dario; Tropea, Stefania [University of Catania, INFN-LNS and INFN-Sez., Catania (Italy); Lubian, Jesus; Garcia, Vantelfo; Paes, Barbara [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Fisica

    2012-07-01

    Full text: The {sup 12}C({sup 18}O,{sup 16}O){sup 14}C and {sup 13}C({sup 18}O,{sup 17}O){sup 14}C transfer reactions have been studied at 84 MeV incident energy at the INFN-LNS laboratory in Catania (Italy). The {sup 16}O and {sup 17}O ejectiles were detected at forward angles by the MAGNEX large acceptance magnetic spectrometer. Q-value spectra up to about 20 MeV and angular distributions were obtained with resolution of about 150 keV in energy and 0.2 deg in angle. In particular, excited states with relevant 1p-3h configuration with respect to the {sup 16}O core are mainly populated by the ({sup 18}O,{sup 17}O) reaction while states with known 2p-4h configuration are excited by the ({sup 18}O,{sup 16}O). This demonstrates the clear selectivity of such reactions. The shape of the measured angular distributions is found to be sensibly dependent on the transferred angular momentum. A theoretical description based on exact finite range coupled reaction channel calculations using the double folding Sao Paulo potential is used for the first time to analyze the data. The good agreement with the experimental cross section demonstrates that, despite the heavy ions involved, the one-step transfer of a two-neutron pair is dominant in the ({sup 18}O,{sup 16}O) reaction. A comparison with Distorted Wave Born Approximation calculations using the same potential shows that effects of channel couplings is visible but small. Supplementary two-neutron sequential transfer calculation are performed within the two-step DWBA formalism, introducing the intermediate partition {sup 13}C + {sup 17}O. This accounts only for a negligible contribution to the absolute cross section. As a consequence, the possibility to extract two-particle spectroscopic factor and, more in general, information on nuclear structure is demonstrated. (author)

  7. Relationships between δ18O in summer precipitation and temperature and moisture trajectories at Muztagata, western China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on summer observations of stable isotope of precipitation at Muztagata, western China, during 2002―2003, this paper presents the relationship between δ18O in precipitation and air temperature, and discusses the effect of moisture transport on δ18O in precipitation. Results show that air temperature correlates positively with δ18O in precipitation, and the temperature effect controls the δ18O of precipitation in this area. The Muztagata region exhibits high δ18O values in summer precipitation, similar to those shown at stations in adjacent regions. According to the results of our model set up to trace the moisture trajectories, the westerlies and local moisture circulation contribute to variations of oxygen isotopes in precipitation. In addition, the impacts of the moisture transport distance, the moisture transport level, and the incursion of the polar air mass also influence the variations of δ18O in precipitation. The moisture origins and transport mechanisms also contribute to the variation of δ18O in precipitation at Muztagata.

  8. An investigation of the controls on Irish precipitation {delta}{sup 18}O values on monthly and event timescales

    Energy Technology Data Exchange (ETDEWEB)

    Baldini, Lisa M.; Baldini, James U.L. [Durham University, Department of Earth Sciences, Durham (United Kingdom); McDermott, Frank; Moellhoff, Martin [University College Dublin, UCD School of Geological Sciences, Dublin 4 (Ireland); Fischer, Matthew J. [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Menai, NSW (Australia)

    2010-11-15

    This two-year study investigates the relative influence of meteorological variables (precipitation amount and temperature), atmospheric circulation, air mass history, and moisture source region on Irish precipitation oxygen isotopes ({delta}{sup 18}O{sub p}) on event and monthly timescales. Single predictor correlations reveal that on the event scale, 20% of {delta}{sup 18}O{sub p} variability is attributable to the amount effect and 7% to the temperature effect while on the monthly timescale the North Atlantic Oscillation accounts for up to 20% of {delta}{sup 18}O{sub p} variability and the amount and temperature effects are not significant. In comparison, multivariate linear regression reveals that the interaction of temperature and precipitation amount explains up to 40% of {delta}{sup 18}O{sub p} variance at event and monthly timescales. Five-day kinematic back trajectories suggest that the amount-weighted mean {delta}{sup 18}O{sub p} value of southerly- and northerly-derived events are lower by 2 permille relative to events derived from the west. Because air mass history and atmospheric circulation appear to influence {delta}{sup 18}O{sub p} in Ireland, Irish paleo-{delta}{sup 18}O{sub p} proxy records are best interpreted as reflecting a combination of parameters, not just paleotemperature or paleorainfall. (orig.)

  9. Thermal neutron capture cross sections for 16,171,18O and 2H

    Science.gov (United States)

    Firestone, R. B.; Revay, Zs.

    2016-04-01

    Thermal neutron capture γ -ray spectra for 16,17,18O and 2H have been measured with guided cold neutron beams from the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) reactor and the Budapest Research Reactor (BRR) on natural and O,1817 enriched D2O targets. Complete neutron capture γ -ray decay schemes for the 16,17,18O(n ,γ ) reactions were measured. Absolute transition probabilities were determined for each reaction by a least-squares fit of the γ -ray intensities to the decay schemes after accounting for the contribution from internal conversion. The transition probability for the 870.76-keV γ ray from 16O(n ,γ ) was measured as Pγ(871 )=96.6 ±0.5 % and the thermal neutron cross section for this γ ray was determined as 0.164 ±0.003 mb by internal standardization with multiple targets containing oxygen and stoichiometric quantities of hydrogen, nitrogen, and carbon whose γ -ray cross sections were previously standardized. The γ -ray cross sections for the O,1817(n ,γ ) and 2H(n ,γ ) reactions were then determined relative to the 870.76-keV γ -ray cross section after accounting for the isotopic abundances in the targets. We determined the following total radiative thermal neutron cross sections for each isotope from the γ -ray cross sections and transition probabilities; σ0(16O )=0.170 ±0.003 mb; σ0(17O )=0.67 ±0.07 mb; σ0(18O )=0.141 ±0.006 mb; and σ0(2H )=0.489 ±0.006 mb.

  10. Nuclear and astrophysical aspects of 18O(p,γ)19F

    International Nuclear Information System (INIS)

    The capture reaction 18O(p,γ)19F has been investigated in the energy range Esub(p) = 80-2200 keV. The seven known resonances have been studied in detail and twelve new resonances have been found. The resonances at Esub(R) = 680, 977 and 1670 keV correspond to new states in 19F. The known resonance at Esub(R) = 631 keV is observed to consist of a doublet (ΔEsub(p) = 7 keV). Information on resonance energies, total and partial widths, branching and mixing ratios and ωγ values is reported. Transition strength arguments as well as analyses of γ-ray angular distribution data combined with results from previous work resulted in Jsup(π) assignments for some of the resonances and low-lying states in 19F. The assignment of several states in 19F as T = 3/2 analogue states of 19O is discussed. A direct capture process to several final states in 19F up to Esub(x) = 8.8 MeV has been observed revealing information on the orbital momenta of the captured protons in the final states, their spectroscopic factors and Jsup(π) assignments for interfering resonances. Special efforts were made to detect this process to states near the proton threshold, which are of importance to stellar hydrogen burning of 18O. The results are compared with corresponding information from other reactions. The investigated energy range of the 18O(p,γ)19F reaction corresponds to the important stellar temperature range of T = 0.01 to 5 X 109 K. The energy-averaged astrophysical reaction rates determined from the present data are compared with previous estimates for this reaction. The data permit reliable conclusions to be drawn concerning the final termination of the CNO tri-cycle. (orig.)

  11. High-frequency observations of δ2H and δ18O in storm rainfall

    Science.gov (United States)

    Stoecker, F.; Klaus, J.; Pangle, L. A.; Garland, C.; McDonnell, J. J.

    2012-12-01

    Stable isotopes ratios of hydrogen (2H/1H) and oxygen (18O/16O) are indispensable tools for investigation of the hydrologic cycle. Recent technological advances with laser spectroscopy now enable high-frequency measurement of key water cycle components. While the controls on rainfall isotope composition have been known generally for some time, our understanding of the effect of inter- and intra-storm processes on fine scale rainfall isotope composition is poorly understood. Here we present a new approach to observe inter- and intra-storm isotope variability in precipitation in high-frequency. We investigate the temporal development of δ2H and δ18O within and between discrete rainstorm. δ2H and δ18O in precipitation was measured from November 2011 to February 2012 in Corvallis, OR using a flow-cell combined with a Liquid Water Isotope Analyzer (LWIA-24d, Los Gatos Research, Inc.). The average sample frequency was 15 samples per hour, resulting in more than 3100 samples during the observation period. 27 separate rainstorms were identified in the dataset based on minimum inter-event time, minimum precipitation depth, and minimum number of isotope measurements. Event meteoric water lines were developed for each event. We observed short-term isotopic patterns (e.g., V-shaped trends), high-rate changes (5.3‰/h) and large absolute changes in isotopic composition (20‰) on intra-event scale. V-shaped trends appeared to be related to individual storm fronts detected by air temperature, cloud heights (NEXRAD radar echo tops) and cloud trajectories (Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT)). Despite this, we could detect no linear correlation between event-based isotopic variables (slope, δ2H-intercept, δ2H, δ18O) and the event meteoric water line. Furthermore, the composite event meteoric water line (i.e. the local meteoric water line) showed a wider spread for heavy isotopes than for light isotopes, caused presumably by different

  12. Microbial, Physical and Chemical Drivers of COS and 18O-CO2 Exchange in Soils

    Science.gov (United States)

    Meredith, L. K.; Boye, K.; Whelan, M.; Pang, E.; von Sperber, C.; Brueggemann, N.; Berry, J. A.; Welander, P. V.

    2015-12-01

    Carbonyl sulfide (COS) and the oxygen isotope composition (δ18O) of CO2 are potential tools for differentiating the contributions of photosynthesis and respiration to the balance of global carbon cycling. These processes are coupled at the leaf level via the enzyme carbonic anhydrase (CA), which hydrolyzes CO2 in the first biochemical step of the photosynthetic pathway (CO2 + H2O ⇌ HCO3- + H+) and correspondingly structural analogue COS (COS + H2O → CO2 + H2S). CA also accelerates the exchange of oxygen isotopes between CO2 and H2O leading to a distinct isotopic imprint [1]. The biogeochemical cycles of these tracers include significant, yet poorly characterized soil processes that challenge their utility for probing the carbon cycle. In soils, microbial CA also hydrolyze COS and accelerate O isotope exchange between CO2 and soil water. Soils have been observed to emit COS by undetermined processes. To account for these soil processes, measurements are needed to identify the key microbial, chemical, and physical factors. In this study, we survey COS and δ18O exchange in twenty different soils spanning a variety of biomes and soil properties. By comparing COS fluxes and δ18O-CO2 values emitted from moist soils we investigate whether the same types of CA catalyze these two processes. Additionally, we seek to identify the potential chemical drivers of COS emissions by measuring COS fluxes in dry soils. These data are compared with soil physical (bulk density, volumetric water content, texture), chemical (pH, elemental analysis, sulfate, sulfur K-edge XANES), and microbial measurements (biomass and phylogeny). Furthermore, we determine the abundance and diversity of CA-encoding genes to directly link CA with measured soil function. This work will define the best predictors for COS fluxes and δ18O-CO2 values from our suite of biogeochemical measurements. The suitability of identified predictor variables can be tested in follow-up studies and applied for modeling

  13. {sup 18}O/{sup 16}O determination in organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Saurer, M.; Siegwolf, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The oxygen isotope ratio in plant material can be used to deduce information about the climate and the environment. We present a simple and fast continuous-flow technique for the determination of the {sup 18}O/{sup 16}O ratio in organic matter. In this method the samples are thermally decomposed in the presence of glassy carbon and the evolving monoxide is used to determine the oxygen ratio. Not only cellulose but also nitrogen-containing materials can be processed when interfering gases (mainly N{sub 2}) are separated from CO by gas chromatography. (author) 2 figs., 2 refs.

  14. Temperature variations in the past 6000 years inferred from δ18O of peat cellulose from Hongyuan, China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Trends of the temperature variations recorded in δ18O in Hongyuan peat cellulose are similar to those recorded in δ 18O of Jinchuan peat cellulose and inδ18O of Dunde ice core. Climate events have been identified to be globallyhomogeneous. Two notable climate transition periods have been detected in the past 6000 years, namely 4000 aBP with climate shifting from cold to warm and 1500aBP with climate shifting from warm to relatively cold. Power spectrum analysiswas performed to investigate the periodical signals in the δ18O time series. Typical periodicities of 1200-1087 a, 752 a, 444 a, 325 a, 213 a, 127-123 a, 88a, 79 a were discovered, indicating an integrated influence on Hongyuan climatefrom solar, monsoon and ocean activities. Solar forcing has been addressed to be the main driving forcing of Hongyuan climate.

  15. A culture-based calibration of benthic foraminiferal paleotemperature proxies: δ18O and Mg/Ca results

    Directory of Open Access Journals (Sweden)

    D. C. McCorkle

    2010-01-01

    Full Text Available Benthic foraminifera were cultured for five months at four temperatures (4, 7, 14 and 21 °C to establish the temperature dependence of foraminiferal δ18O and Mg/Ca. Two Bulimina species (B. aculeata and B. marginata were most successful, adding chambers at all four temperatures and reproducing at 7 and 14 °C. Foraminiferal δ18O values displayed ontogenetic variations, with lower values in younger individuals. The δ18O values of adult specimens decreased with increasing temperature in all but the 4 °C treatment, exhibiting a relationship consistent with previous δ18O paleotemperature calibration studies. Foraminiferal Mg/Ca values, determined by laser ablation inductively coupled plasma mass spectrometry, were broadly consistent with previous Mg/Ca calibration studies, but extremely high values in the 4 °C treatment and higher than expected values at two of the other three temperatures make it challenging to interpret these results.

  16. Establishing a grassland signature in veins: 18O in the leaf water of C3 and C4 grasses

    OpenAIRE

    Helliker, Brent R.; Ehleringer, James R.

    2000-01-01

    We show that 18O evaporative enrichment of bulk leaf water in grass species can be significantly more enriched than predicted by the Craig–Gordon model, with C4 grasses considerably more enriched than C3 grasses. Our results suggest that the unanticipated 18O leaf water enrichment of grasses is attributable to the progressive evaporative enrichment along parallel veins (a function of both leaf length and interveinal distance), a pattern that does not occur in Dicotyledonous species. We propos...

  17. Inferring heterogeneity in aquitards using high-resolution deltaD and delta18O profiles.

    Science.gov (United States)

    Hendry, M Jim; Wassenaar, L I

    2009-01-01

    Vertical depth profiles of pore water isotopes (deltaD and delta18O) in clay-rich aquitards have been used to show that solute transport is dominated by molecular diffusion, to define the timing of geologic events, and to estimate vertical hydraulic conductivity. The interpretation of the isotopic profiles in these studies was based on pore water samples collected from piezometers installed in nests (typically 4 to 15 piezometers) over depths of 10 to 80 m. Data from piezometer nests generally have poor vertical resolution (meters), raising questions about their capacity to reveal the impact of finer scale heterogeneities such as permeable sand bodies or fractured till zones on solute transport. Here, we used high-resolution (30-cm) depth profiles of deltaD and delta18O from two continuously cored boreholes in a till aquitard to provide new insights into the effects of sand bodies on solute transport. High-resolution core-derived profiles indicate that such heterogeneities can cause major deviations from one-dimensional diffusion profiles. Further, comparison of piezometer-measured values with best-fit diffusion trends shows subtle deviations, suggesting the presence of heterogeneities that should not be ignored. High-resolution profiles also more clearly defined the contact between the highly fractured oxidized zone and the underlying unoxidized zone than the piezometers. PMID:19735307

  18. Impacts of Tibetan Plateau uplift on atmospheric dynamics and associated precipitation δ18O

    Science.gov (United States)

    Botsyun, Svetlana; Sepulchre, Pierre; Risi, Camille; Donnadieu, Yannick

    2016-06-01

    Palaeoelevation reconstructions of mountain belts have become a focus of modern science since surface elevation provides crucial information for understanding both geodynamic mechanisms of Earth's interior and the influence of mountain growth on climate. Stable oxygen isotopes palaeoaltimetry is one of the most popular techniques nowadays, and relies on the difference between δ18O of palaeo-precipitation reconstructed using the natural archives, and modern measured values for the point of interest. Our goal is to understand where and how complex climatic changes linked with the growth of mountains affect δ18O in precipitation. For this purpose, we develop a theoretical expression for the precipitation composition based on the Rayleigh distillation and the isotope-equipped atmospheric general circulation model LMDZ-iso outputs. Experiments with reduced height over the Tibetan Plateau and the Himalayas have been designed. Our results show that the isotopic composition of precipitation is very sensitive to climate changes related to the growth of the Himalayas and Tibetan Plateau. Specifically our simulations suggest that only 40 % of sampled sites for palaeoaltimetry depict a full topographic signal, and that uplift-related changes in relative humidity (northern region) and precipitation amount (southern region) could explain absolute deviations of up to 2.5 ‰ of the isotopic signal, thereby creating biases in palaeoelevation reconstructions.

  19. Millennial-scale features in ?18O from a stalagmite in the eastern United States

    Science.gov (United States)

    Hardt, B. F.; Doctor, D. H.; Gao, Y.; Rowe, H. D.; Cheng, H.; Edwards, R.

    2013-12-01

    The oxygen isotope record of calcite from a stalagmite collected from Grand Caverns in Virginia, USA shows evidence of millennial-scale variability that appears to be coherent with Dansgaard/Oeschger events observed in Greenland ice. Sample GC-S02 grew from 82 - 13 ka BP and ranges in δ18O composition from -8 to -4 ‰ (VPDB) with multiple instances of millennial-scale changes in excess of 1‰. As δ18O in GC-S02 is more positive during MIS 2 than MIS 3, change in mean annual temperature is not a likely explanation for the observed variability. The carbon and oxygen isotopic records of calcite are independent and show no evidence of covaration (r = -0.1). Changes in the seasonal timing of precipitation provides an alternate explanation for the data, particularly given the potential for warm- and cool-season precipitation to come from different sources (Gulf of Mexico versus the Atlantic ocean). Grand Caverns is located in the Shenandoah River watershed within the Appalachian Great Valley, suggesting a meaningful role for Atlantic moisture. The age model is based on high-precision U-Th ages, making this record a potential benchmark for the region.

  20. 18O depletion in monsoon rain relates to large scale organized convection rather than the amount of rainfall.

    Science.gov (United States)

    Lekshmy, P R; Midhun, M; Ramesh, R; Jani, R A

    2014-07-11

    Oxygen isotopic variations in rainfall proxies such as tree rings and cave calcites from South and East Asia have been used to reconstruct past monsoon variability, mainly through the amount effect: the observed (18)O depletion of rain with increasing amount, manifested as a negative correlation of the monthly amount of tropical rain with its δ(18)O, both measured at the same station. This relation exhibits a significant spatial variability, and at some sites (especially North-East and peninsular India), the rainfall proxies are not interpretable by this effect. We show here that relatively higher (18)O-depletion in monsoon rain is not related necessarily to its amount, but rather, to large scale organized convection. Presenting δ(18)O analyses of ~654 samples of daily rain collected during summer 2012 across 9 stations in Kerala, southern India, we demonstrate that although the cross correlations between the amounts of rainfall in different stations is insignificant, the δ(18)O values of rain exhibit highly coherent variations (significant at P = 0.05). Significantly more (18)O-depletion in the rain is caused by clouds only during events with a large spatial extent of clouds observable over in the south eastern Arabian Sea.

  1. Mechanisms linking metabolism of Helicobacter pylori to (18)O and (13)C-isotopes of human breath CO2.

    Science.gov (United States)

    Som, Suman; De, Anulekha; Banik, Gourab Dutta; Maity, Abhijit; Ghosh, Chiranjit; Pal, Mithun; Daschakraborty, Sunil B; Chaudhuri, Sujit; Jana, Subhra; Pradhan, Manik

    2015-06-03

    The gastric pathogen Helicobacter pylori utilize glucose during metabolism, but the underlying mechanisms linking to oxygen-18 ((18)O) and carbon-13 ((13)C)-isotopic fractionations of breath CO2 during glucose metabolism are poorly understood. Using the excretion dynamics of (18)O/(16)O and (13)C/(12)C-isotope ratios of breath CO2, we found that individuals with Helicobacter pylori infections exhibited significantly higher isotopic enrichments of (18)O in breath CO2 during the 2h-glucose metabolism regardless of the isotopic nature of the substrate, while no significant enrichments of (18)O in breath CO2 were manifested in individuals without the infections. In contrast, the (13)C-isotopic enrichments of breath CO2 were significantly higher in individuals with Helicobacter pylori compared to individuals without infections in response to (13)C-enriched glucose uptake, whereas a distinguishable change of breath (13)C/(12)C-isotope ratios was also evident when Helicobacter pylori utilize natural glucose. Moreover, monitoring the (18)O and (13)C-isotopic exchange in breath CO2 successfully diagnosed the eradications of Helicobacter pylori infections following a standard therapy. Our findings suggest that breath (12)C(18)O(16)O and (13)C(16)O(16)O can be used as potential molecular biomarkers to distinctively track the pathogenesis of Helicobacter pylori and also for eradication purposes and thus may open new perspectives into the pathogen's physiology along with isotope-specific non-invasive diagnosis of the infection.

  2. An isotope mass balance model for the correlation of freshwater bivalve shell (Unio pictorum carbonate δ18O to climatic conditions and water δ18O in Lake Balaton (Hungary

    Directory of Open Access Journals (Sweden)

    Gabriella SCHÖLL-BARNA

    2011-08-01

    Full Text Available The oxygen isotope composition of bivalve shells (δ18Oshell can potentially record environmental variability of shallow lakes and therefore it has been extensively used as a proxy in the reconstruction of past climate and environmental conditions. As δ18Oshell reflects - besides the water temperature - the oxygen isotope composition of lake water (δ18OL, it is required to interpret the quality and impact of parameters influencing the δ18OL. Using the isotope mass balance model, I tested the hypothesis that Balaton lake water δ18O variability can be described as a result of the combined effects of three main climatic parameters such as river runoff, precipitation and evaporation. I calculated δ18OL time series for the period 1999-2008 for the whole water body at Siófok (eastern part of Lake Balaton, Hungary based on measured precipitation, inflow and evaporation amount and measured inflow, precipitation δ18O and calculated vapour δ18O data. The comparison of the modelled δ18OL time series to measured surface δ18OL data revealed that δ18O of Balaton water is sensitive for variation of climatic parameters. This variability is most striking at the surface, while according to the results of the model, the whole water body itself is less sensitive. Monthly differences suggest that generally during summer the whole water body is mixed up, while moderate isotope stratification (0.3-0.7‰ difference between surface and whole water body can be assumed in early spring and autumn. Predictions of shell δ18O values were made using the measured surface water δ18O data and the modelled δ18O values for the whole water body. High-resolution sampling was conducted on two Unio pictorum shells covering the period of 2001-2008, and both predictions were compared to measured shell δ18O records. The results showed that the prediction for the whole water body gives a better fit to the measured shell δ18O, suggesting that the whole water body better

  3. Isolating relative humidity: dual isotopes d18O and dD as deuterium deviations from the global meteoric water line

    Science.gov (United States)

    Cellulose d18O and dD can provide insights on climates and hydrological cycling in the distant past and how these factors differ spatially. However, most studies of plant cellulose have used only one isotope, most commonly d18O, resulting in difficulties partitioning variation in d18O of precipitati...

  4. First results from a novel methodological approach for δ18O analyses of sugars using GC-Py-IRMS

    Science.gov (United States)

    Zech, Michael; Saurer, Matthias; Tuthorn, Mario; Rinne, Katja; Werner, Roland; Juchelka, Dieter; Siegwolf, Rolf; Glaser, Bruno

    2013-04-01

    Although the instrumental coupling of gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-Py-IRMS) for compound-specific δ18O analyses is commercially available for more than 10 years, this method is hardly applied by isotope researchers so far. Using GC-Py-IRMS, Zech and Glaser (2009) and Zech et al. (2013; 2012) developed and applied a method, which allows determining δ18O of hemicellulose-derived sugar biomarkers extracted from soils and sediments. However, the used methylboronic acid (MBA) derivatization is suitable only for pentoses and deoxyhexoses, not for hexoses. Here we present first GC-Py-IRMS results for TMS-(trimethylsilyl)-derivatives of plant sap-relevant sugars (glucose, fucose, sucrose, raffinose) and a polyalkohol (pinitol) produced using BSTFA (N,O-Bis(trimethylsilyl)trifluoroacetamide) as the derivatization reagent. Particularly, we focus on sucrose, which is the most important transport sugar in plants and hence of utmost relevance in plant physiology and in tree-ring studies. Replicate analyses of sucrose standards with known δ18O values suggest that the δ18O measurements are not stable over several days. A calibration (including a drift correction) against an external sucrose standard is hence essential when measuring sample batches. Furthermore, we observed a large dependence of the δ18O values on the analyte amount (area), which needs to be considered by a respective correction procedure. Tests with 18O-enriched water do not provide any evidence for oxygen exchange reactions between water and sucrose, glucose and raffinose. Finally we present the first application of compound-specific δ18O analyses from natural samples, namely from seven needle extracts (soluble carbohydrates) from a Siberian study area. Both the δ18O amplitude and values of sucrose are considerably higher (32.1‰ to 40.1‰) compared to the δ18O amplitude and values of bulk needle extract (24.6‰ to 27.2‰). We found positive correlation (although

  5. High- & Low-δ18O magma: Comparative study of crustal and mantle plagiogranites from the Oman ophiolite

    Science.gov (United States)

    Alberts, R. C.; Grimes, C. B.; Koepke, J.; Erdmann, M.; Kitajima, K.; Spicuzza, M. J.; Valley, J. W.

    2015-12-01

    Plagiogranite (PLGT) from the crust and mantle sections of the Oman ophiolite preserve widely varied δ18O values that monitor different processes occurring during ophiolite construction. Mantle-like δ18O values are expected if MORB fractionation played a dominant role in PLGT genesis. Magmatic values (monitored here by zircon) shifted away from the mantle-like range indicate open system processes which include partial melting of hydrothermally-altered crust or influx of subduction-related, sediment-derived melt. Zircon (zrn) and quartz (qtz) from twenty-four new samples of PLGT from the crustal and mantle sections of the Oman ophiolite were analyzed for δ18O. Rock-averaged δ18O from the sheeted dikes (zrn: 4.3-4.5‰, qtz: 6.7-6.9‰) and dike-gabbro transition (zrn: 3.9-4.8‰, qtz: 4.7-7.7‰) are mostly below values in magmatic equilibrium with MORB (zrn = 5.2±0.5‰, qtz = 7.0-7.5‰). δ18O for PLGT in the gabbro section (zrn: 4.8-5.1‰, qtz: 7.7-8.3‰) are mostly mantle-like. Quartz is generally found to be more variable than coexisting zrn and likely experienced some sub-solidus exchange. When organized into a relative structural position, δ18Ozrn values typically increase with depth. The lowest δ18Ozrn are observed near the dike-gabbro transition and are consistent with petrogenesis involving hydrous partial melting of mafic crust previously hydrothermally-altered at high-T. The return to nominally mantle-equilibrated δ18Ozrn deeper in the gabbro section may reflect decreasing seawater-signatures of fluids penetrating to depth, lower water/rock ratios, or extreme fractional crystallization. Crustal PLGT thus predate the development of high δ18O signatures in the upper oceanic crust as it cools and experiences low temperature hydrothermal alteration. Mantle PLGT intrusions (1-3 m thick) from the Haylayn block extend to considerably higher rock-averaged δ18O values (zrn: 5.1-15.4‰, qtz: 7.0-18.5‰). Individual rocks (5 samples) were uniform in

  6. Tracking Cats: Problems with Placing Feline Carnivores on δ18O, δD Isoscapes

    Science.gov (United States)

    Pietsch, Stephanie J.; Hobson, Keith A.; Wassenaar, Leonard I.; Tütken, Thomas

    2011-01-01

    Background Several felids are endangered and threatened by the illegal wildlife trade. Establishing geographic origin of tissues of endangered species is thus crucial for wildlife crime investigations and effective conservation strategies. As shown in other species, stable isotope analysis of hydrogen and oxygen in hair (δDh, δ18Oh) can be used as a tool for provenance determination. However, reliably predicting the spatial distribution of δDh and δ18Oh requires confirmation from animal tissues of known origin and a detailed understanding of the isotopic routing of dietary nutrients into felid hair. Methodology/Findings We used coupled δDh and δ18Oh measurements from the North American bobcat (Lynx rufus) and puma (Puma concolor) with precipitation-based assignment isoscapes to test the feasibility of isotopic geo-location of felidae. Hairs of felid and rabbit museum specimens from 75 sites across the United States and Canada were analyzed. Bobcat and puma lacked a significant correlation between H/O isotopes in hair and local waters, and also exhibited an isotopic decoupling of δ18Oh and δDh. Conversely, strong δD and δ18O coupling was found for key prey, eastern cottontail rabbit (Sylvilagus floridanus; hair) and white-tailed deer (Odocoileus virginianus; collagen, bone phosphate). Conclusions/Significance Puma and bobcat hairs do not adhere to expected pattern of H and O isotopic variation predicted by precipitation isoscapes for North America. Thus, using bulk hair, felids cannot be placed on δ18O and δD isoscapes for use in forensic investigations. The effective application of isotopes to trace the provenance of feline carnivores is likely compromised by major controls of their diet, physiology and metabolism on hair δ18O and δD related to body water budgets. Controlled feeding experiments, combined with single amino acid isotope analysis of diets and hair, are needed to reveal mechanisms and physiological traits explaining why felid hair does

  7. Cold air incursions, δ18O variability, and monsoon dynamics associated with snow days at Quelccaya Ice Cap, Peru

    Science.gov (United States)

    Hurley, John V.; Vuille, Mathias; Hardy, Douglas R.; Burns, Stephen J.; Thompson, Lonnie G.

    2015-08-01

    Quelccaya Ice Cap in the Andes of Peru contains an annually resolved δ18O record covering the past 1800 years; yet atmospheric dynamics associated with snow deposition and δ18O variability at this site are poorly understood. Here we make use of 10 years of snow pit and short core δ18O data and hourly snow-height measurements obtained by an automated weather station deployed at the ice cap's summit to analyze linkages between snowfall, δ18O, and the South American summer monsoon (SASM). Snow accumulation peaks in December and is negative May-September. Snow δ18O values decrease gradually through austral summer from about -17 to -24‰. Surface snow δ18O is altered after deposition during austral winter from about -24 to -15‰. More than 70% of the total snow accumulation is tied to convection along the leading edge of cold air incursions of midlatitude air advected equatorward from southern South America. Snowfall amplitude at Quelccaya Ice Cap varies systematically with regional precipitation, atmospheric dynamics, midtroposphere humidity, and water vapor δD. Strongest snowfall gains correspond with positive precipitation anomalies over the western Amazon Basin, increased humidity, and lowered water vapor δD values, consistent with the "amount effect." We discuss ventilation of the monsoon, modulated by midlatitude cold air advection, as potentially diagnostic of the relationship between SASM dynamics and Quelccaya snowfall. Results will serve as a basis for development of a comprehensive isotopic forward model to reconstruct past monsoon dynamics using the ice core δ18O record.

  8. LED-based Fourier transform spectroscopy of 16O12C18O and 12C18O2 in the 11,260-11,430 cm-1 range

    Science.gov (United States)

    Serdyukov, V. I.; Sinitsa, L. N.; Lugovskoi, A. A.; Borkov, Yu. G.; Tashkun, S. A.; Perevalov, V. I.

    2016-07-01

    The absorption spectrum of the 16O12C18O and 12C18O2 carbon dioxide isotopologues has been recorded in the 11,260- 11,430 cm-1 spectral range using Bruker IFS 125 HR Fourier transform spectrometer with resolution 0.05 cm-1 at temperature 297 K and path length 24 m. The 18O enriched sample of carbon dioxide at total pressure 96.5 mbar was used for these purposes. The spectrometer used LED emitter as a light source. This gave possibility to reach the minimal detectable absorption coefficient αmin~1.4×10-7 cm-1 using 23,328 scans. In the recorded spectrum we have assigned the 00051-00001 band for both 16O12C18O and 12C18O2 isotopologues using the predictions performed within the framework of the method of effective operators. The line positions and intensities of the observed bands are found. The comparison of the observed and predicted line positions and intensities is performed confirming good accuracy of the predictions. The spectroscopic parameters for the observed bands are determined.

  9. Rapid uplift of the Altiplano revealed through 13C-18O bonds in paleosol carbonates.

    Science.gov (United States)

    Ghosh, Prosenjit; Garzione, Carmala N; Eiler, John M

    2006-01-27

    The elevation of Earth's surface is among the most difficult environmental variables to reconstruct from the geological record. Here we describe an approach to paleoaltimetry based on independent and simultaneous determinations of soil temperatures and the oxygen isotope compositions of soil waters, constrained by measurements of abundances of 13C-18O bonds in soil carbonates. We use this approach to show that the Altiplano plateau in the Bolivian Andes rose at an average rate of 1.03 +/- 0.12 millimeters per year between approximately 10.3 and approximately 6.7 million years ago. This rate is consistent with the removal of dense lower crust and/or lithospheric mantle as the cause of elevation gain.

  10. Effect of (2)H and (18)O water isotopes in kinesin-1 gliding assay.

    Science.gov (United States)

    Maloney, Andy; Herskowitz, Lawrence J; Koch, Steven J

    2014-01-01

    We show for the first time the effects of heavy-hydrogen water ((2)H2O) and heavy-oxygen water (H2 (18)O) on the gliding speed of microtubules on kinesin-1 coated surfaces. Increased fractions of isotopic waters used in the motility solution decreased the gliding speed of microtubules by a maximum of 21% for heavy-hydrogen and 5% for heavy-oxygen water. We also show that gliding microtubule speed returns to its original speed after being treated with heavy-hydrogen water. We discuss possible interpretations of these results and the importance for future studies of water effects on kinesin and microtubules. We also discuss the implication for using heavy waters in biomolecular devices incorporating molecular motors. PMID:24711961

  11. Two-neutron stripping in ({sup 18}O, {sup 16}O) and (t,p) reactions

    Energy Technology Data Exchange (ETDEWEB)

    Cavallaro, M.; Agodi, A.; Carbone, D.; Cunsolo, A. [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, I-95125 Catania (Italy); Bondì, M.; Cappuzzello, F.; Nicolosi, D.; Tropea, S. [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, I-95125 Catania, Italy and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95125 Catania (Italy); Borello-Lewin, T.; Rodrigues, M. R. D. [Instituto de Física - Universidade de São Paulo, Rua do Matão Travessa R Nr.187 CEP 05508-090 Cidade Universitária, São Paulo (Brazil); De Napoli, M. [INFN - Sezione di Catania, Via S. Sofia 64, I-95125 Catania (Italy); Garcia, V. N. [Instituto de Física, Universidade Federal Fluminense, Avenida Litoranea s/n, Gragoata, 24210-340, Niteroi, RJ (Brazil); Linares, R.; Lubian, J.; Paes, B. [Instituto de Física, Universidade Federal Fluminense, Avenida Litoranea s/n, Gragoata , 24210-340, Niteroi, RJ (Brazil); Foti, A. [Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95125 Catania, Italy and INFN - Sezione di Catania, Via S. Sofia 64, I-95125 Catania (Italy)

    2014-11-11

    The {sup 12}C({sup 18}O,{sup 16}O){sup 14}C reactions has been investigated at 84 MeV incident energy. The charged ejectiles produced in the reaction have been momentum analyzed and identified by the MAGNEX magnetic spectrometer. Q-value spectra have been extracted with an energy resolution of 160 keV (Full Width at Half Maximum) and several known bound and resonant states of {sup 14}C have been identified up to 15 MeV. In particular, excited states with dominant 2p - 4h configuration are the most populated. The absolute values of the cross sections have been extracted showing a striking similarity with those measured for the same transitions by (t,p) reactions. This indicates that the effect of the {sup 16}O core is negligible in the reaction mechanism.

  12. Evidence for solar forcing of climate variation from δ18O of peat cellulose

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    There have been a number of investigations for examining the possible link between long-term climate variability and solar activity.A continuous δ18O record of peat cellulose covering the past 6000 years and the response of climate variation inferred from the proxy record to solar forcing are reported.Results show that during the past 5000 years the abrupt climate variations,including 17 warming and 17 cooling,and a serious of periodicities,such as 86,101,110,127,132,140,155,207,245,311,820 and 1050 years,are strikingly correlative to the changes of solar irradiation and periodicity.These observations are considered as further evidence for a close relationship between solar activity and climate variations on time scales of decades to centuries.

  13. Evidence for solar forcing of climate variation from δ18O of peat cellulose

    Institute of Scientific and Technical Information of China (English)

    洪业汤; 刘东生; 姜洪波; 周立平; 洪冰; 朱泳煊; 李汉鼎; 冷雪天; 秦小光; 王羽; 林庆华; 曾毅强

    2000-01-01

    There have been a number of investigations for examining the possible link between long-term climate variability and solar activity. A continuous δ18O record of peat cellulose covering the past 6 000 years and the response of climate variation inferred from the proxy record to solar forcing are reported. Results show that during the past 5 000 years the abrupt climate variations, including 17 warming and 17 cooling, and a serious of periodicities, such as 86, 101, 110,127, 132, 140, 155, 207, 245, 311, 820 and 1 050 years, are strikingly correlative to the changes of solar irradiation and periodicity. These observations are considered as further evidence for a close relationship between solar activity and climate variations on time scales of decades to centuries.

  14. δ18O isotope map-generation of European mineral waters, applications and limits

    International Nuclear Information System (INIS)

    There is an increasing demand for independent analytical methods which can control the geographical origin of food. The EU project TRACE was started with the aim to develop a general understanding of the relation of the geo-bio-climatic environment and the isotope and elemental signature in food commodities. Besides mineral water, the agricultural products wheat, honey, olive oil and lamb meat are investigated. As one part of the study a detailed δ18O map for groundwater will be generated by the isotope results of 600 samples of European mineral waters. These groundwater isotope maps provide a multitude of applications not only for authenticity of food, but for groundwater recharge and climate studies, criminal forensics as well as archaeology too. (author)

  15. Origin of summer monsoon rainfall identified by δ18O in precipitation

    Institute of Scientific and Technical Information of China (English)

    PANG Hongxi; HE Yuanqing; ZHANG Zhonglin; LU Aigang; GU Juan; ZHAO Jingdong

    2005-01-01

    A negative correlation between δ18O in monsoon precipitation and f, the ratio of precipitable water in monsoon region to that in water source area, is hypothesized.Using the Rayleigh model, a new method for identifying origin of summer monsoon rainfall is developed based on the hypothesis. In order to validate the method, the isotopic data at New Delhi, a typical station in the southwest monsoon region, and Hong Kong, a typical station in the southeast monsoon region, were collected and analyzed for case studies.The case studies indicate that the water source areas of the monsoon rainfall at the two stations identified by the method are accordant with the general atmosphere circulation patterns. The method developed in this paper is significantly important for tracing the origin of summer monsoon precipitation.

  16. The First Detailed 2H and 18O Isoscapes of Freshwater in Scotland

    Science.gov (United States)

    Meier-Augenstein, W.; Hoogewerff, J.; Kemp, H. F.; Frew, D.

    2012-04-01

    Scotland's freshwater lochs and reservoirs provide a vital resource for sustaining biodiversity, agriculture, food production as well as for human consumption. Regular monitoring of freshwater quality by the Scottish Environmental Protection Agency (SEPA) fulfils the legislative requirements but new scientific methods involving stable isotope analysis present an opportunity for delivering on current and nascent government policies [1] and gaining a greater understanding of Scottish waters and their importance in the context of climate change, environmental sustainability and the aforementioned functions. In brief, 2H and 18O isoscapes of Scottish freshwater could be used to support fundamental and applied research in: • Climate change - These first ever isoscapes will provide a baseline against which future environmental impact can be assessed due to changes in the characteristic isotope composition of freshwater lochs and reservoirs. • Scottish branding - Location specific stable isotope signatures of Scottish freshwater have the potential to be used as a tool for provenancing and thus protecting premium Scottish produce such as Scottish beef, Scottish berries and Scottish Whisky. During 2011, freshwater samples were collected with the support of SEPA from more than 80 freshwater lochs and reservoirs across Scotland. Here we present the result of the 2H and 18O stable isotope analyses of these water samples together with the first isoscapes generated based on these data. [1] Adaptation Framework - Adapting Our Ways: Managing Scotland's Climate Risk (2009): Scotland's Biodiversity: It's in Your Hands - A strategy for the conservation and enhancement of biodiversity in Scotland (2005); Recipe For Success - Scotland's National Food and Drink Policy (2009); Scottish Planning Policy Environmental Report (2009); Scottish Planning Policy (SPP) 15 Planning for Rural Development (2005); National Planning Policy Guideline (NPPG) 14: Natural Heritage (1999).

  17. An explanation for the 18O excess in Noelaerhabdaceae coccolith calcite

    Science.gov (United States)

    Hermoso, M.; Minoletti, F.; Aloisi, G.; Bonifacie, M.; McClelland, H. L. O.; Labourdette, N.; Renforth, P.; Chaduteau, C.; Rickaby, R. E. M.

    2016-09-01

    Coccoliths have dominated the sedimentary archive in the pelagic environment since the Jurassic. The biominerals produced by the coccolithophores are ideally placed to infer sea surface temperatures from their oxygen isotopic composition, as calcification in this photosynthetic algal group only occurs in the sunlit surface waters. In the present study, we dissect the isotopic mechanisms contributing to the "vital effect", which overprints the oceanic temperatures recorded in coccolith calcite. Applying the passive diffusion model of carbon acquisition by the marine phytoplankton widely used in biogeochemical and palaeoceanographic studies, our results suggest that the oxygen isotope offsets from inorganic calcite in fast dividing species Emiliania huxleyi and Gephyrocapsa oceanica originates from the legacy of assimilated 18O-rich CO2 that induces transient isotopic disequilibrium to the internal dissolved inorganic carbon (DIC) pool. The extent to which this intracellular isotopic disequilibrium is recorded in coccolith calcite (1.5 to +3‰ over a 10 to 25 °C temperature range) is set by the degree of isotopic re-equilibration between CO2 and water molecules before intracellular mineralisation. We show that the extent of re-equilibration is, in turn, set by temperature through both physiological (dynamics of the utilisation of the DIC pool) and thermodynamic (completeness of the re-equilibration of the relative 18O-rich CO2 influx) processes. At the highest temperature, less ambient aqueous CO2 is present for algal growth, and the consequence of carbon limitation is exacerbation of the oxygen isotope vital effect, obliterating the temperature signal. This culture dataset further demonstrates that the vital effect is variable for a given species/morphotype, and depends on the intricate relationship between the environment and the physiology of biomineralising algae.

  18. Historical droughts in northern Vietnam captured by variability in speleothem δ18O

    Science.gov (United States)

    Hardt, B. F.; McGee, D.; Burns, S. J.; Hieu, N.; Hieu, D. T.

    2015-12-01

    Speleothem records overlapping with the historical period offer valuable comparisons of documentary evidence with speleothem proxy data. These records provide opportunities to 'ground-truth' the paleo-record, fill in gaps in the historical record, and more confidently extent the paleo-record into deeper time. Here we present isotopic results from a stalagmite collected in northern Vietnam spanning 1200 to 1950 CE, a period with a rich historical record in Vietnam. This sample adds significantly to the relatively sparse paleoclimate record from Southeast Asia. The record includes several multi-decadal positive excursions of ≥1 per mille in calcite δ18O. A preliminary age model, based on six U/Th ages, suggests possible correspondence to noted droughts from the historical record, including the Angkor Droughts, the Ming Dynasty Drought, the Strange Parallels Drought, and the Victorian Holocaust Drought. As modeling studies indicate a strong correlation between rainfall δ18O and both the intensity of summer monsoon winds and summer rainfall over northern Vietnam (e.g., Liu et al., 2014), these excursions are consistent with a decrease in regional precipitation. The Vietnam record shows an overall negative trend during the Little Ice Age. The study site is located well south of the westerly wind belt, ruling out a shift between monsoonal and mid-latitude circulation systems as a likely explanation for the northern Vietnam record. We explore the correspondence between our record and other proxy data from Southeast Asia and suggest possible implications of the differences between Vietnamese and Chinese speleothem records during the Little Ice Age. References cited: Liu Z., Wen X., Brady E. C., Otto-Bliesner B., Yu G., Lu H., Cheng H., Wang Y., Zheng W., Ding Y., Edwards R. L., Cheng J., Liu W. and Yang H. (2014) Chinese cave records and the East Asia Summer Monsoon. Quaternary Science Reviews 83, 115-128.

  19. Preferential formation of 13C- 18O bonds in carbonate minerals, estimated using first-principles lattice dynamics

    Science.gov (United States)

    Schauble, Edwin A.; Ghosh, Prosenjit; Eiler, John M.

    2006-05-01

    Equilibrium constants for internal isotopic exchange reactions of the type: Ca12C18O16O2+Ca13C16O3↔Ca13C18O16O2+Ca12C16O3 for individual CO 32- groups in the carbonate minerals calcite (CaCO 3), aragonite (CaCO 3), dolomite (CaMg(CO 3) 2), magnesite (MgCO 3), witherite (BaCO 3), and nahcolite (NaHCO 3) are calculated using first-principles lattice dynamics. Calculations rely on density functional perturbation theory (DFPT) with norm-conserving planewave pseudopotentials to determine the vibrational frequencies of isotopically substituted crystals. Our results predict an ˜0.4‰ excess of 13C18O16O22- groups in all studied carbonate minerals at room-temperature equilibrium, relative to what would be expected in a stochastic mixture of carbonate isotopologues with the same bulk 13C/ 12C, 18O/ 16O, and 17O/ 16O ratios. The amount of excess 13C18O16O22- decreases with increasing temperature of equilibration, from 0.5‰ at 0 °C to <0.1‰ at 300 °C, suggesting that measurements of multiply substituted isotopologues of carbonate could be used to infer temperatures of ancient carbonate mineral precipitation and alteration events, even where the δ 18O of coexisting fluids is uncertain. The predicted temperature sensitivity of the equilibrium constant is ˜0.003‰/°C at 25 °C. Estimated equilibrium constants for the formation of 13C18O16O22- are remarkably uniform for the variety of minerals studied, suggesting that temperature calibrations will also be applicable to carbonate minerals not studied here without greatly compromising accuracy. A related equilibrium constant for the reaction: Ca12C18O16O2+Ca12C17O16O2↔Ca12C18O17O16O+Ca12C16O3 in calcite indicates formation of 0.1‰ excess 12C 18O 17O 16O 2- at 25 °C. In a conventional phosphoric acid reaction of carbonate to form CO 2 for mass-spectrometric analysis, molecules derived from 13C18O16O22- dominate (˜96%) the mass 47 signal, and 12C 18O 17O 16O 2- contributes most of the remainder (3%). This suggests

  20. δ18O and δ13C Analysis in Tree Rings of Pterocarpus angolensis Growing in Zimbabwe

    Science.gov (United States)

    McLeran, K.; Schoof, J. T.; Lefticariu, L.; Therrell, M.

    2015-12-01

    Instrumental weather records in southern Africa are largely limited to the last 100 years and documentary weather-related data are rare prior to the 1800s, hindering our understanding of the natural and/or anthropogenic factors that influence climate variability over this region. Measuring stable isotopes ratios (commonly 13C/12C and 18O/16O) in tree rings can provide a good proxy for extending climate data beyond the instrumental record. The objective of this study is to characterize historical variations in the climatology underlying extreme climatic events in Zimbabwe using instrumental climate records (precipitation and temperature) and a multi-proxy approach (ring width, δ18O, and δ13C) for dendroclimatic proxy reconstructions. A 90-year (1900-1990) δ18O and δ13C tree ring record using four Pterocarpus angolensis samples is being developed and compared to tree ring width, monthly, seasonal, and annual precipitation totals, meteoric water δ18O values, and mean monthly and seasonal temperature. Preliminary results indicate significant correlations between the average δ18O record and the previous year December precipitation totals (r=0.41, pZimbabwe.

  1. The high-resolution climaterecorded in the δ18O of Porites lutea from the Nansha Islands of China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A Porites lutea core from Yongshu Reef of Nansha Islands covering 50 years growth history was analyzed for oxygen isotopic composition with monthly and seasonally resolution. The calibration of the δ18O with the instrumental temperature indicated that the coral δ18O is a good indicator for sea surface temperature (SST) and air temperature ( t ). It can be used to reconstruct the SST and air temperature of the Yongshu Reef sea area. In addition, the coral δ18O provides signatures for the intensity of the East Asia monsoon and it is a record for the activities of El Ni(n~)o events. With the calibrated SST and air temperature formulas, the most recent fifty years SST and air temperature were reconstructed based on the coral δ18O, thus back up the understanding of the climate of Nansha Islands to 1950, far beyond the limit of the instrumental recording since September 1988. It was found that, in general, increasing 1℃ air temperature results in 0.24‰ decrease in skeletal δ18O.

  2. The interstellar C18O/C17O ratio in the solar neighbourhood: The rho Oph cloud

    CERN Document Server

    Wouterloot, J G A; Henkel, C

    2004-01-01

    Observations of up to ten carbon monoxide (CO and isotopomers) transitions are presented to study the interstellar C18O/C17O ratio towards 21 positions in the nearby (d~140pc) low-mass star forming cloud rho Oph. A map of the C18O J=1-0 distribution of parts of the cloud is also shown. An average 12C18O/12C17O isotopomeric ratio of 4.11 +/- 0.14, reflecting the 18O/17O isotope ratio, is derived from Large Velocity Gradient (LVG) calculations. From LTE column densities we derive a ratio of 4.17 +/-0.26. These calculations also show that the kinetic temperature decreases from about 30 K in the cloud envelope to about 10 K in the cloud cores. This decrease is accompanied by an increase of the average molecular hydrogen density from 10^4 cm-3 to >10^5 cm-3. Towards some lines of sight C18O optical depths reach values of order unity.

  3. Aplicaciones de los marcadores biogeoquímicos δ13C y δ18O en Mazama temama Aplications of biogeochemical markers δ13C and δ18O in Mazama temama

    Directory of Open Access Journals (Sweden)

    Víctor Adrián Pérez-Crespo

    2012-06-01

    Full Text Available Se presentan los valores isotópicos de δ13C y δ18O obtenidos del esmalte dental de un temazate procedente de un sitio arqueológico. Dichos valores indican que este cérvido tenía una dieta ramoneadora y habitaba en una zona de vegetación cerrada.We present isotopic values of δ13C and δ18O obtained from dental enamel in a brocket deer individual found in an archeological site. Those values show that the individual had a browser in an area of closed vegetation.

  4. Aplicaciones de los marcadores biogeoquímicos δ13C y δ18O en Mazama temama Aplications of biogeochemical markers δ13C and δ18O in Mazama temama

    OpenAIRE

    Víctor Adrián Pérez-Crespo; Ximena Ulloa-Montemayor; Guillermo Acosta-Ochoa; Joaquín Arroyo-Cabrales; Luis M. Alva-Valdivia; Pedro Morales-Puente; Edith Cienfuegos-Alvarado

    2012-01-01

    Se presentan los valores isotópicos de δ13C y δ18O obtenidos del esmalte dental de un temazate procedente de un sitio arqueológico. Dichos valores indican que este cérvido tenía una dieta ramoneadora y habitaba en una zona de vegetación cerrada.We present isotopic values of δ13C and δ18O obtained from dental enamel in a brocket deer individual found in an archeological site. Those values show that the individual had a browser in an area of closed vegetation.

  5. H_2^{16}O and H_2^{18}O Maser Emission from Gas-Dust Clouds

    CERN Document Server

    Nesterenok, Aleksandr; 10.1134/S1063773711070036

    2011-01-01

    The collisional pumping of H_2^{16}O and H_2^{18}O masers in hot dense gas-dust clouds has been simulated numerically. New data on the rate coefficients for collisional transitions from Faure et al. (2007) were used in the calculations. The possibility of detecting H_2^{18}O emission in 22.2-GHz H_2^{16}O maser sources is investigated. The medium is shown to become optically thick in the H_2^{16}O lines for which an inverted level population is observed at H_2O column densities of ~10^{19}-10^{20} cm^{-2}. A simultaneous observation of H_2^{18}O emission and H_2^{16}O maser emission in the same source will allow the physical conditions in the gas-dust cloud to be refined.

  6. Holocene East Asian summer monsoon records in northern China and their inconsistency with Chinese stalagmite δ18O records

    Science.gov (United States)

    Liu, Jianbao; Chen, Jianhui; Zhang, Xiaojian; Chen, Fahu

    2016-04-01

    Monsoon precipitation over China exhibits large spatial differences. It has been found that a significantly enhanced East Asian summer monsoon (EASM) is characterized by increased rainfall in northern China and by reduced rainfall in southern China, and this relationship occurs on different time scales during the Holocene. This study presents results from a diverse range of proxy paleoclimatic records from northern China where precipitation variability is traditionally considered as an EASM proxy. Our aim is to evaluate the evolution of the EASM during the Holocene and to compare it with all of the published stalagmite δ18O records from the Asian Monsoon region in order to explore the potential mechanism(s) controlling the Chinese stalagmite δ18O. We found that the intensity of the EASM during the Holocene recorded by the traditional EASM proxy of moisture (or precipitation) records from northern China are significantly different from the Chinese stalagmite δ18O records. The EASM maximum occurred during the mid-Holocene, challenging the prevailing view of an early Holocene EASM maximum mainly inferred from stalagmite δ18O records in eastern China. In addition, all of the well-dated Holocene stalagmite δ18O records, covering a broad geographical region, exhibit a remarkably similar trend of variation and are statistically well-correlated on different time scales, thus indicating a common signal. However, in contrast with the clear consistency in the δ18O values in all of the cave records, both instrumental and paleoclimatic records exhibit significant spatial variations in rainfall on decadal-to- centennial time scales over eastern China. In addition, both paleoclimatic records and modeling results suggest that Holocene East Asian summer monsoon precipitation reached a maximum at different periods in different regions of China. Thus the stalagmite δ18O records from the EASM region should not be regarded as a reliable indicator of the strength of the East

  7. δ13c-δ18O Covariance:An Effective Indicator of Hydrological Closure for Lakes?

    Institute of Scientific and Technical Information of China (English)

    CHEN Jing'an; WANG Fushun; WAN Guojiang; TANG Degui; David Dian ZHANG; HUNAG Ronggui; LI Jian; XIAO Tangfu

    2008-01-01

    The correlation between the Δ13c and 18O in primary carbonates is affected by several factors such as hydrological balance, total CO2 concentrations, climatic condition and lake productivity.The influence of these factors on the Δ13c-δ18 correlation may be different on different time scales. In this paper, two different-type lakes in southwestern China, Lake Erhal and Lake Chenghai, are selected to investigate the influence of climatic pattern on the Δ13c-Δ18o correlation and to evaluate the reliability of the Δ13c-Δ18o covariance as an indicator of hydrological closure. The results show that there exists good correlation between the Δ13c and Δ18o in Lake Erhai (overflowing open lake) and inLake Chenghal (closed lake). This suggests that the Δ13c-Δ18o covariance may be not an effective indicator of hydrological closure for lakes, especially on short time scales. On the one hand, a hydrologically open lake may display covariant Δ13c and δ18 as a result of climatic influence. The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of the Δ13c-δ18 covariance in Lake Erhai and Lake Chenghal. On the other hand, a hydrologically closed lake unnecessarily displays covariant trends between Δ13c and δ18 because of the buffering effect of high CO2 concentration on the Δ13c shift in hyper-alkaline lakes. We should be the buffering feeect of high CO2 concentration on the 13Cshift in hyper-alkaline lakes.We should be prudent when we use the covariance between 13C and 18O to judge the hydrological closure of lake.

  8. A new interpretation of the two-step δ18O signal at the Eocene-Oligocene boundary

    Directory of Open Access Journals (Sweden)

    H. A. Dijkstra

    2010-07-01

    Full Text Available The most marked step in the global climate transition from "Greenhouse" to "Icehouse" Earth occurred at the Eocene-Oligocene (E–O boundary, 33.7 Ma. Evidence for climatic changes comes from many sources, including the marine benthic δ18O record, showing an increase by 1.2–1.5‰ at this time. This positive excursion is characterised by two steps, separated by a plateau. The increase in δ18O values has been attributed to rapid glaciation of the Antarctic continent, previously ice-free. Simultaneous changes in the δ13C record are indicative of a greenhouse gas control on climate. Previous studies show that a decline in pCO2 beyond a certain threshold value may have initiated the growth of a Southern Hemispheric ice sheet. These studies were not able to conclusively explain the remarkable two-step profile in δ18O. Furthermore, they did not address the potential role of changes in ocean circulation in the E–O transition. Here a new interpretation of the δ18O signal is presented, based on model simulations using a simple coupled 8-box-ocean, 4-box-atmosphere model with an added land ice component. The model was forced with a slowly decreasing atmospheric carbon dioxide concentration. It is argued that the first step in the δ18O represents a shift in meridional overturning circulation from a Southern Ocean to a bipolar source of deep-water formation, which is associated with a cooling of the deep sea. This shift can be initiated by a small density perturbation in the model, although there is also a parameter regime for which the shift occurs spontaneously. The second step in the δ18O profile occurs due to a rapid glaciation of the Antarctic continent. This new interpretation is a robust outcome of our model and is in good agreement with proxy data.

  9. The 18O/16O Ratio of 2-Billion-Year-Old Seawater Inferred from Ancient Oceanic Crust.

    Science.gov (United States)

    Holmden, C; Muehlenbachs, K

    1993-03-19

    An oxygen isotope profile of the 2-billion-year-old Purtuniq ophiolite overlaps with similar profiles of younger ophiolites and the modern oceanic crust. This overlap implies (i) that there was a similar style of seawater-ocean crust interaction during the past 2 billion years; (ii) that the oxygen isotope composition of early Proterozoic seawater was similar to the modern value; (iii) that early Proterozoic sea-floor spreading rates were similar to, or greater than, average modern rates; and (iv) that early Proterozoic carbonate rocks and cherts with low (18)O/(16)O ratios do not reflect global-scale (18)O depletion of early Proterozoic oceans. PMID:17816892

  10. Latest miocene benthic delta/sup 18/O changes, global ice volume, sea level and the Messinian salinity crisis

    Energy Technology Data Exchange (ETDEWEB)

    Hodell, D.A.; Elmstrom, K.M.; Kennett, J.P.

    1986-04-03

    Oxygen isotope evidence indicates high but variable delta/sup 18/O values in benthic foraminiferal calcite during the latest Miocene and earliest Pliocene. These high values may represent increases in global ice volume and associated sea-level fall. The delta/sup 18/O record resembles glacial/interglacial cycles, but with only one-third the amplitude of the late Pleistocene signal. This variability may reflect instability in the Antarctic ice sheet, and palaeomagnetic correlation points to an isotopic event coinciding with the isolation and desiccation of the Mediterranean basin during the latest Messinian.

  11. Sub-barrier enhancement of fusion as compared to a microscopic method in 18O+12C

    OpenAIRE

    Steinbach, T. K.; Vadas, J.; Schmidt, J.; Haycraft, C.; Hudan, S.; deSouza, R. T.; Baby, L. T.; Kuvin, S. A.; Wiedenhöver, I.; Umar, A. S.; Oberacker, V. E.

    2014-01-01

    Measurement of the energy dependence of the fusion cross-sec on at sub-barrier energies provides an important test for theoretical models of fusion. To extend the measurement of fusion cross-sections in the sub-barrier domain for the 18O+12C system. Use the new experimental data to confront microscopic calculations of fusion. Evaporation residues produced in fusion of 18O ions with 12C target nuclei were detected with good geometric efficiency and identified by measuring their energy and time...

  12. Planktic δ18O records in the northern South China Sea: MIS 5.5 vs MIS 1

    Science.gov (United States)

    Sarnthein, M.; Sadatzki, H.

    2012-04-01

    Benthic δ18O records show peak and average levels for Marine Isotope Stage (MIS) 5.5, which are 0.1-0.2 ‰ lighter than during MIS 1, a shift that largely results from changes in global ice volume. In planktic δ18O records of the northern South China Sea this trend may grow by 0.1-0.2 ‰ due to both a rise in sea surface temperatures (SST) during MIS 5.5 and enhanced freshwater input. On the other hand, dominant sources of atmospheric humidity may alter from the far distant equatorial Indian (18O depleted) to the nearby West Pacific Ocean (18O enriched), thus significantly influencing the δ18O value of the monsoon-controlled freshwater discharge to the South China Sea (Pausata et al., 2011), and accordingly, the local planktic δ18O signal of surface waters. We tested the role of these possibly opposed factors by means of planktic δ18O records with centennial-scale resolution at ODP Site 1144 (2040 m w.d.; Bühring et al., 2004) and MD05-2904 (2070 m w.d.; Ge et al., 2010). In contrast to an expected 18O depletion for MIS 5.5 of 0.3 ‰, the pertinent core sections were 18O enriched by 0.4 ‰ as compared to MIS 1. This positive shift may either suggest a major and dominant switch in atmosph¬eric water supply from Indian to nearby West Pacific sources or exhibit a loss of the sediment section crucial for MIS 5.5, that is a distinct stratigraphic gap. Highly resolved δ18O records obtained for comparison from three sediment cores retrieved nearby at much greater water depths (ODP Sites 1145, 1146; Core 17924) clearly show for MIS-5.5 the expected δ18O level that is slightly lighter than that of MIS 1, in harmony with increased SST (He et al., 2008), and thus support the hiatus model. It is also corroborated by large fields of (modern) erosional furrows which are generated by a vigorous inflow of Upper Pacific Deepwater passing along the continental slope off Hong Kong near 2350 m w.d. During interglacial MIS 5.5, this current had probably moved upslope by

  13. The Impact of Clouds on Ecosystem-Atmosphere CO18O Exchanges in the U.S. Great Plains

    Science.gov (United States)

    Still, C. J.; Riley, W. J.; Biraud, S. C.; Noone, D. C.; Berry, J. A.

    2005-12-01

    The downward excursion in δ18O of atmospheric CO2 observed during the 1990s and the large interannnual variability characteristic of this isotopologue are not understood. We hypothesize that these variations in δ18O of atmospheric CO2 may be linked to global-scale variations in cloud cover and its influence on biosphere-atmosphere CO18O exchanges. Recent work has demonstrated the influence of clouds on canopy photosynthesis through increases in the diffuse radiation fraction and relative humidity, combined with decreases in leaf temperature. In concert, these alterations tend to increase canopy photosynthesis, which should also increase CO18O fluxes. However, photosynthetic CO18O fluxes also depend on the δ18O of leafwater, and enhanced cloudiness should decrease the δ18O of leafwater by enhancing relative humidity. Thus, the net impact of differing cloud cover on biosphere-atmosphere CO18O exchanges is difficult to predict. To capture these contrasting effects, we employed a comprehensive ecosystem isotope model (ISOLSM) in the southern great plains region of Oklahoma and Kansas. This region is particularly amenable for such a study because of the density of cloud property and radiation measurements. The region contains natural and agricultural ecosystems representing a variety of photosynthetic pathways and growth forms, including tallgrass prairie pastures, broadleaf forests, and crops. To drive the model across the entire region, we used Mesonet meteorological data collected at 120 stations in 2004, as well as precipitation δ18O values from the National Atmospheric Deposition Program network. LAI profiles from 2004 were derived from MODIS data. Our results suggest a large impact of clouds on photosynthetic CO2 and CO18O fluxes across this region. In an unstressed broadleaf deciduous forest (LAI=6.3), three sequential midsummer days with contrasting cloud cover illustrate this impact. Julian Day 222 is sunny, JD 223 is partly cloudy, and JD 224 is very

  14. Initial isotopic geochemistry ({delta} 18 O, {delta} D) of fluids from wells of the Los Humeros, Pue., geothermal field; Geoquimica isotopica ({delta} 18 O, {delta} D) inicial de fluidos de pozos del campo geotermico de Los Humeros, Pue.

    Energy Technology Data Exchange (ETDEWEB)

    Barragan Reyes, Rosa Maria; Arellano Gomez, Victor Manuel [Instituto de Investigaciones Electricas, Gerencia de Geotermia, Cuernavaca, Morelos (Mexico)]. E-mail: rmb@iie.org.mx; Ramirez Montes, Miguel; Tovar Aguado, Rigoberto [Comision Federal de Electricidad, Gerencia de Proyectos Geotermoelectricos, Morelia, Michoacan (Mexico)

    2010-01-15

    Isotopic data ({delta} 18 O, {delta} D) from fluids from production wells at the Los Humeros, Pue., geothermal field were analyzed to investigate the possible origin of these fluids and the dominant processes of the reservoir at its initial state. According to pre-exploitation data, it is suggested the Los Humeros reservoir fluids are made of a mixture of meteoric water of very light isotopic composition (paleo-fluids) and andesitic water. The relationship {delta} D vs {delta} 18 O from pre-exploitation data indicates the produced fluids are composed of a mixture of (at least) two fluids with distinct isotopic compositions. At the more enriched end of the mixing relationship are the isotopic compositions of the wells H-23 and H-18 (located in the southern area of the field), while the lighter fluids were found in well H-16 (originally) and then in well H-16 (repaired). It was found that the liquid phases of deep wells are more enriched in {delta} 18 O while the shallow wells present lower values, suggesting a convection process at the initial state. Based on this isotopic profile, it is considered that even the production depths of the wells H-1, H-12 and H-16 (repaired) are just about the same, but their respective isotopic compositions are quite different. The {delta} 18 O value for well H-16 (repaired) seems to be that of condensate steam, while the corresponding values for wells H-1 and H-12 fall within the value interval of the deep wells (H-23). This suggests wells H-1 and H-12 are collecting very deep fluids enriched in {delta} 18 O. These results could be useful in creating a conceptual model of the reservoir. [Spanish] Se analizaron datos isotopicos ({delta}18 O, {delta}D) de los fluidos de pozos productores del campo geotermico de Los Humeros, Pue., para investigar el posible origen de los fluidos asi como los procesos dominantes del yacimiento en su estado inicial. De acuerdo con datos previos a la explotacion, se plantea que los fluidos del yacimiento

  15. Oxygen determination in materials by 18O(p,αγ)15N nuclear reaction

    Science.gov (United States)

    Kumar, Sanjiv; Sunitha, Y.; Reddy, G. L. N.; Sukumar, A. A.; Ramana, J. V.; Sarkar, A.; Verma, Rakesh

    2016-07-01

    The paper presents a proton induced γ-ray emission method based on 18O(p,αγ)15N nuclear reaction to determine bulk oxygen in materials. The determination involves the measurement of 5.27 MeV γ-rays emitted following the de-excitation of 15N nuclei. A description of the energetics of the reaction is given to provide an insight into the origin of 5.27 MeV γ-rays. In addition, thick target γ-ray yields and the limits of detection are measured to ascertain the analytical potential of the reaction. The thick-target γ-ray yields are measured with a high purity germanium detector and a bismuth germanate detector at 0° as well as 90° angles in 3.0-4.2 MeV proton energy region. The best limit of detection of about 1.3 at.% is achieved at 4.2 MeV proton energy for measurements at 0° as well 90° angles with the bismuth germanate detector while the uncertainty in quantitative analysis is methodology is demonstrated by determining oxygen in several oxide as well as non-oxide materials.

  16. Freshwater budget of the Canada Basin, Arctic Ocean, from salinity, δ18O, and nutrients

    Science.gov (United States)

    Yamamoto-Kawai, M.; McLaughlin, F. A.; Carmack, E. C.; Nishino, S.; Shimada, K.

    2008-01-01

    The contribution of freshwater components (e.g., meteoric, sea ice, and Pacific water) in the Canada Basin is quantified using salinity, δ18O, and nutrient data collected in 2003 and 2004. The penetration depth of sea ice meltwater is limited to the upper 30 m, and brine, rejected during sea ice formation, is observed from 30 to 250 m depth. The fraction of meteoric water is high in the upper 50 m and decreases with depth. Pacific water entering via Bering Strait is the main source of freshwater below 50 m depth. Bering Strait throughflow, which transports Pacific water with salinity 32.5 together with meteoric water supplied upstream of the Bering Strait, contributes up to 75% of freshwater input (>3200 km3 a-1) to the Canada Basin. The mean residence time of Pacific water in the Canada Basin is estimated to be 11 years. Precipitation and river runoff from both North American and Eurasian continents add >800 km3 a-1 and sea ice formation removes export of ice and liquid fresh water from the Canada Basin contributes ˜40% of the freshwater flux from the Arctic Ocean to the North Atlantic Ocean.

  17. States of 15C via the (18O,16O) reaction

    CERN Document Server

    Cappuzzello, F; Cunsolo, A; Foti, A; Orrigo, S E A; Rodrigues, M R D; Borello-Lewin, T; Carbone, D; Schillaci, C

    2010-01-01

    A study of the 15C states was pursued in 2008 at the Catania INFN-LNS laboratory by the 13C(18O,16O)15C reaction at 84 MeV incident energy. The 16O ejectiles were detected at forward angles by the MAGNEX magnetic spectrometer. Thanks to an innovative technique the ejectiles were identified without the need of time of flight measurements. Exploiting the large momentum acceptance (25%) and solid angle (50 msr) of the spectrometer, the 15C energy spectra were obtained with a quite relevant yield up to about 20 MeV excitation energy. The application of the powerful technique of the trajectory reconstruction did allow to get an energy resolution of about 250 keV FWHM, limited mainly by straggling effects. The spectra show several known low lying states up to about 7 MeV excitation energy as well as two unknown resonant structures at about 11.4 and 13.5 MeV. The strong excitation of these latter together with the measured width of about 2 MeV FWHM could indicate the presence of collective modes of excitation connec...

  18. The ({sup 18}O, {sup 16}O) reaction as a probe for nuclear spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cappuzzello, F.; Bondì, M.; Nicolosi, D.; Tropea, S. [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, I-95125 Catania, Italy and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95125 Catania (Italy); Agodi, A.; Carbone, D.; Cavallaro, M.; Cunsolo, A. [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, I-95125 Catania (Italy); Borello-Lewin, T.; Rodrigues, M. R. D. [Instituto de Física - Universidade de São Paulo, Rua do Matão Travessa R Nr.187, 05508-090 Cidade Universitária, São Paulo (Brazil); De Napoli, M. [INFN - Sezione di Catania, Via S. Sofia 64, I-95125 Catania (Italy); Linares, R. [Instituto de Física, Universidade Federal Fluminense, Avenida Litoranea s/n, Gragoata, 24210-340, Niteroi, RJ (Brazil); Foti, A. [Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95125 Catania, Italy and INFN - Sezione di Catania, Via S. Sofia 64, I-95125 Catania (Italy)

    2014-11-11

    The response of nuclei to the ({sup 18}O, {sup 16}O) two-neutron transfer reaction at 84 MeV incident energy has been systematically studied at the Catania INFN-LNS laboratory. The experiments were performed using several solid targets from light ({sup 9}Be, {sup 11}B, {sup 12,13}C, {sup 16}O, {sup 28}Si) to heavy ones ({sup 58,64}Ni, {sup 120}Sn, {sup 208}Pb). The {sup 16}O ejectiles were detected at forward angles by the MAGNEX magnetic spectrometer. Exploiting the large momentum acceptance (−10%, +14%) and solid angle (50 msr) of the spectrometer, energy spectra were obtained with a relevant yield up to about 20 MeV excitation energy. The application of the powerful trajectory reconstruction technique did allow to get energy spectra with energy resolution of about 150 keV and angular distributions with angular resolution better than 0.3°. A common feature observed with light nuclei is the appearance of unknown resonant structures at high excitation energy. The strong population of these latter together with the measured width can reveal the excitation of a collective mode connected with the transfer of a pair.

  19. Incorporation and disappearance of oxygen-18 in lung from mice exposed to 1 ppm (18)O sub 3 (1)

    Energy Technology Data Exchange (ETDEWEB)

    Santrock, J.; Hatch, G.E.; Slade, R.; Hayes, J.M.

    1989-01-01

    In the study, (18)O(3) was used as a tracer for inhaled ozone in mice. The amount of ozone-derived oxygen (ODO) in the lungs was determined by measuring the amount of oxygen-18 in excess of the natural abundance level which remained covalently bound to organic constituents of lung tissue following exposure to 1 ppm (18)O(3). The rate of disappearance of ODO from the lungs was determined by quantifying the rate of decrease of oxygen-18 in excess of the natural abundance level in lung tissue from mice exposed to 1 ppm (18)O(3) for 45 min. With exposure to 1 ppm (18)O(3), ozone-derived oxygen accumulated in lung tissue at a rate of 4.38 pmoles of ODO/mg/min. ODO had a half-life in lung tissue of approximately 6 h. It was impossible to determine accurately the dose of ozone to tissue from these data. However, it was estimated that in each animal a minimum of 44 pmoles of O(3) reacted with molecular constituents of lung tissue every minute of exposure to 1 ppm O(3).

  20. Incorporation and disappearance of oxygen-18 in lung from mice exposed to 1 ppm 18O3.

    Science.gov (United States)

    Santrock, J; Hatch, G E; Slade, R; Hayes, J M

    1989-03-15

    In this study, 18O3 was used as a tracer for inhaled ozone in mice. The amount of ozone-derived oxygen (ODO) in the lungs was determined by measuring the amount of oxygen-18 in excess of the natural abundance level which remained covalently bound to organic constituents of lung following exposure to 1 ppm 18O3 for less than or equal to 60 min. The rate of disappearance of ODO from the lungs was determined by quantifying the rate of decrease of oxygen-18 in excess of the natural abundance level in lung from mice exposed to 1 ppm 18O3 for 45 min. With exposure to 1 ppm 18O3. ODO accumulated in lung at a rate of 4.38 pmol/mg dry weight/min. Ozone-derived oxygen had a half-life in lung of approximately 6 hr. We estimate that a minimum of 44 pmol of O3 reacted with lung every minute of exposure to 1 ppm O3. PMID:2929022

  1. Incorporation and disappearance of oxygen-18 in lung from mice exposed to 1 ppm /sup 18/O/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Santrock, J.; Hatch, G.E.; Slade, R.; Hayes, J.M.

    1989-03-15

    In this study, /sup 18/O/sub 3/ was used as a tracer for inhaled ozone in mice. The amount of ozone-derived oxygen (ODO) in the lungs was determined by measuring the amount of oxygen-18 in excess of the natural abundance level which remained covalently bound to organic constituents of lung following exposure to 1 ppm /sup 18/O/sub 3/ for less than or equal to 60 min. The rate of disappearance of ODO from the lungs was determined by quantifying the rate of decrease of oxygen-18 in excess of the natural abundance level in lung from mice exposed to 1 ppm /sup 18/O/sub 3/ for 45 min. With exposure to 1 ppm /sup 18/O/sub 3/. ODO accumulated in lung at a rate of 4.38 pmol/mg dry weight/min. Ozone-derived oxygen had a half-life in lung of approximately 6 hr. We estimate that a minimum of 44 pmol of O3 reacted with lung every minute of exposure to 1 ppm O3.

  2. A model of the 4000-year paleohydrology (δ18O) record from Lake Salpetén, Guatemala

    Science.gov (United States)

    Rosenmeier, Michael F.; Brenner, Mark; Hodell, David A.; Martin, Jonathan B.; Curtis, Jason H.; Binford, Michael W.

    2016-03-01

    A simple mass-balance model provides insights into the influence of catchment vegetation changes and climate variability on the hydrologic and stable oxygen isotope (δ18O) evolution of Lake Salpetén, in the Maya Lowlands of northern Guatemala. Model simulations for the last 4000 years incorporate pollen-inferred changes in vegetation cover and account for 75% of the variance observed in the biogenic carbonate δ18O record from a long lake sediment core. Vegetation-driven hydrologic changes, however, failed to capture the full range of late Holocene sediment core δ18O variability. The model requires incorporation of additional shifts in catchment vegetation cover, inclusion of regional precipitation changes, or likely both, to explain the fluctuations observed in the lake core oxygen isotope record. Climatic interpretation of the model results suggests that there was relatively greater moisture availability between about 2400 and 1800 years ago, but increased δ18O values centered at ~ 3300, 2900, 500, and 200 calendar years before present (cal yr BP) indicate abrupt precipitation decreases. There is evidence for protracted aridity between 1500 and 800 cal yr BP.

  3. A coral δ18O record of ENSO driven sea surface salinity variability in Fiji (south -western tropical Pacific)

    Science.gov (United States)

    Le Bec, Nolwenn; Julliet-Leclerc, Anne; Corrège, Thierry; Blamart, Dominique; Delcroix, Thierry

    2000-12-01

    The role of salinity in the dynamics and thermodynamics of El Niño - Southern Oscillation (ENSO) events is increasingly being investigated. However, instrumental records of salinity are scarce and short in the tropical Pacific, and there is a clear need for a reliable salinity proxy to extend our knowledge of ENSO through time. Here, we present 40 years of δ18O data from a Fiji coral (16°48‧S-177°27‧E). The coral δ18O signal integrates both sea surface temperature (SST) and sea surface salinity (SSS) variations. On a seasonal timescale, δ18O is mainly driven by SST changes whereas on an interannual ENSO timescale, it is almost exclusively affected by SSS variability. Since interannual fluctuations of SSS are rather well correlated to the Southern Oscillation Index in Fiji, coral δ18O can be used to reconstruct paleo-salinity data with some level of confidence. This may help for tracking ENSO influences back in time.

  4. Abraham Reef Stable Isotope Data (delta 13C, delta 18O, delta 14C) for 1635-1957

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Site: Abraham Reef, 22ó 06'S, 153ó 00'E, Porites australiensus, Radiocarbon (delta 14C) and Stable Isotope (del 18O and del 13C) results from bi-annual samples from...

  5. Efficient Total Chemical Synthesis of (13) C=(18) O Isotopomers of Human Insulin for Isotope-Edited FTIR.

    Science.gov (United States)

    Dhayalan, Balamurugan; Fitzpatrick, Ann; Mandal, Kalyaneswar; Whittaker, Jonathan; Weiss, Michael A; Tokmakoff, Andrei; Kent, Stephen B H

    2016-03-01

    Isotope-edited two-dimensional Fourier transform infrared spectroscopy (2 D FTIR) can potentially provide a unique probe of protein structure and dynamics. However, general methods for the site-specific incorporation of stable (13) C=(18) O labels into the polypeptide backbone of the protein molecule have not yet been established. Here we describe, as a prototype for the incorporation of specific arrays of isotope labels, the total chemical synthesis-via a key ester insulin intermediate-of 97 % enriched [(1-(13) C=(18) O)Phe(B24) ] human insulin: stable-isotope labeled at a single backbone amide carbonyl. The amino acid sequence as well as the positions of the disulfide bonds and the correctly folded structure were unambiguously confirmed by the X-ray crystal structure of the synthetic protein molecule. In vitro assays of the isotope labeled [(1-(13) C=(18) O)Phe(B24) ] human insulin showed that it had full insulin receptor binding activity. Linear and 2 D IR spectra revealed a distinct red-shifted amide I carbonyl band peak at 1595 cm(-1) resulting from the (1-(13) C=(18) O)Phe(B24) backbone label. This work illustrates the utility of chemical synthesis to enable the application of advanced physical methods for the elucidation of the molecular basis of protein function. PMID:26715336

  6. δ18O record and temperature change over the past 100 years in ice cores on the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    YAO; Tandong; GUO; Xuejun; Lonnie; Thompson; DUAN; Keqin; WANG; Ninglian; PU; Jianchen; XU; Baiqing; YANG; Xiaoxin; SUN; Weizhen

    2006-01-01

    The 213 m ice core from the Puruogangri Ice Field on the Tibetan Plateau facilitates the study of the regional temperature changes with its δ18O record of the past 100 years. Here we combine information from this core with that from the Dasuopu ice core (from the southern Tibetan Plateau), the Guliya ice core (from the northwestern Plateau) and the Dunde ice core (from the northeastern Plateau) to learn about the regional differences in temperature change across the Tibetan Plateau. The δ18O changes vary with region on the Plateau, the variations being especially large between South and North and between East and West. Moreover, these four ice cores present increasing δ18O trends, indicating warming on the Tibetan Plateau over the past 100 years. A comparative study of Northern Hemisphere (NH) temperature changes, the δ18O-reflected temperature changes on the Plateau, and available meteorological records show consistent trends in overall warming during the past 100 years.

  7. Improved online δ18O measurements of nitrogen- and sulfur-bearing organic materials and a proposed analytical protocol

    Science.gov (United States)

    Qi, H.; Coplen, T.B.; Wassenaar, L.I.

    2011-01-01

    It is well known that N2 in the ion source of a mass spectrometer interferes with the CO background during the δ18O measurement of carbon monoxide. A similar problem arises with the high-temperature conversion (HTC) analysis of nitrogenous O-bearing samples (e.g. nitrates and keratins) to CO for δ18O measurement, where the sample introduces a significant N2 peak before the CO peak, making determination of accurate oxygen isotope ratios difficult. Although using a gas chromatography (GC) column longer than that commonly provided by manufacturers (0.6 m) can improve the efficiency of separation of CO and N2 and using a valve to divert nitrogen and prevent it from entering the ion source of a mass spectrometer improved measurement results, biased δ18O values could still be obtained. A careful evaluation of the performance of the GC separation column was carried out. With optimal GC columns, the δ18O reproducibility of human hair keratins and other keratin materials was better than ±0.15 ‰ (n = 5; for the internal analytical reproducibility), and better than ±0.10 ‰ (n = 4; for the external analytical reproducibility).

  8. Influence of Changing Atmospheric Circulation on Precipitation δ 18O-Temperature Relations in Canada during the Holocene

    Science.gov (United States)

    Edwards, Thomas W. D.; Wolfe, Brent B.; Macdonald, Glen M.

    1996-11-01

    Postglacial precipitation δ 18O history has been reconstructed for two regions of Canada. Long-term shifts in the oxygen-isotope composition of annual precipitation (δ 18O p) in southern Ontario appear to have occurred with a consistent isotope-temperature relation throughout the past 11,500 14C yr. The modern isotope-temperature relation in central Canada near present boreal treeline evidently became established between 5000 and 4000 years ago, although the relation during the last glacial maximum and deglaciation may also have been similar to present. In the early Holocene, however, unusually high δ 18O papparently persisted, in spite of low temperature locally, probably associated with high zonal index. A rudimentary sensitivity analysis suggests that a small reduction in distillation of moisture in Pacific air masses traversing the western Cordillera, perhaps accompanied by a higher summer:winter precipitation ratio, could have been responsible for the observed effect. Equivalent isotope-temperature "anomalies" apparently occurred elsewhere in western North America in response to changing early-Holocene atmospheric circulation patterns, suggesting that a time-slice map of δ 18O pfor North America during this period might provide a useful target for testing and validation of atmospheric general circulation model simulations using isotopic water tracers.

  9. The evolution of Phanerozoic seawater - Isotope paleothermometry finds consensus on Early Paleozoic warmth and constant seawater δ18O

    Science.gov (United States)

    Grossman, E. L.; Henkes, G. A.; Passey, B. H.; Shenton, B.; Yancey, T. E.; Perez-Huerta, A.

    2015-12-01

    Evolution of metazoan life is closely linked to the Phanerozoic evolution of ocean temperatures and chemistry. Oxygen isotopic evidence for early Phanerozoic paleotemperatures has been equivocal, with decreasing δ18O values with age being interpreted as warmer early oceans, decreasing seawater δ18O with age, or increasing diagenetic alteration in older samples. Here we compare an updated compilation of oxygen isotope data for carbonate and phosphate fossils and microfossils (Grossman, 2012, Geol. Time Scale, Elsevier, 195-220) with a compilation of new and existing clumped isotope data. Importantly, these data are curated based on sample preservation with special consideration given to screening techniques, and tectonic and burial history. Burial history is critical in the preservation of carbonate clumped isotope temperatures in particular, which can undergo reordering in the solid state. We use a model derived for reordering kinetics (Henkes et al., 2014, Geochim. Cosmochim. Acta 139:362-382) to screen clumped isotope data for the effects of solid-state burial alteration. With minor but significant exceptions (Late Cretaceous, Early Triassic), average δ18O values (4 m.y. window, 2 m.y. steps) for post-Devonian brachiopods, belemnites, and foraminifera, representing tropical-subtropical surface ocean conditions, yield average isotopic temperatures below 30°C (assuming a seawater δ18O value [ -1‰ VSMOW] of an "ice-free" world). In contrast, Ordovician to Devonian data show sustained temperatures of 35-40°C. Likewise, isotopic paleotemperatures from conodont apatite, known to be resistant to isotopic exchange, follow the same pattern. Clumped isotope data derived from Paleozoic brachiopod shells that experienced minimal burial (< 100 °C) and <1% reordering according to the taxon-specific clumped isotope reordering model yield typical temperatures of 25-30°C for the Carboniferous, and 35-40°C for the Ordovician-Silurian. Inserting clumped temperatures and

  10. Convenient recycling and reuse of bombarded [18O]H2O for the production and the application of [18F]F−

    International Nuclear Information System (INIS)

    The limited availability and the increasing demands of [18O]H2O force the reuse of bombarded [18O]H2O for the production of [18F]F− at least for the purposes of research. Therefore, inorganic and organic contaminants have to be removed from the [18O]H2O after bombardment. We present a simple, effective, easy-handling and reliable method of [18O]H2O purification including oxidation and distillation. The obtained recycled [18O]H2O had comparable quality to commercially distributed [18O]water. This was confirmed by a detailed comparison of produced radionuclides and their activities and the application of [18F]F− for the automated synthesis of [18F]fluspidine. - Highlights: • A reliable recycling procedure of irradiated (bombarded) enriched [18O]H2O is described. • Two methods for the oxidation of organic contaminants followed by low temperature distillation are presented. • The characterisation revealed [18O]H2O with high purity, and the production of [18F]F− and its use in radiosyntheses confirm a high quality of the [18O]H2O for the purposes of research

  11. Clumped Isotope Verification of δ18O-Based Freshwater Mussel Shell Growth Chronology for a High-Resolution Climate and River Discharge Record

    Science.gov (United States)

    VanPlantinga, A.; Grossman, E. L.; Passey, B. H.; Randklev, C.

    2015-12-01

    Isotope profiles in freshwater mussel shells can be used to reconstruct climate, water source, and river discharge, but problems arise from variable water temperature and δ18O. To resolve this complexity and expand the application of isotope sclerochronology to the study of past river systems, we measured δ18O and Δ47 in two common freshwater mussel species from the Brazos River in Texas. To compare the environmental record with the shell record and develop a sclerochronology, weekly water temperature and δ18O data were collected from the Brazos River near College Station from January 2012 to August 2013. The river data reveal complex, irregular patterns for predicted aragonite δ18O. Comparing δ18O profiles from micromilled transects (70-200 µm increments) of coeval shell growth within and between shells yielded consistent patterns. Shell δ18O can be accurately matched to predicted δ18O, providing a chronology of shell growth. However, without a water temperature and δ18O record, interpreting a sclerochronology would be impossible. Shell Δ47 can potentially provide a seasonal chronology to verify the δ18O sclerochronology, which would be invaluable for the use of δ18O sclerochronology in historical and ancient shells. For Δ47 analyses, samples were taken at 0.5 mm resolution in presumed seasonal dark and light growth bands. Clumped temperatures range between 21 and 35 ± 4˚C (Henkes et al., 2013) and track the river temperature record, supporting the interpreted shell δ18O chronology. Shell Δ47-calculated water δ18O values range from -1.2 to 1.5 ± 0.9‰ and match river δ18O. High-resolution shell δ18O profiles combined with Δ47 temperatures can reconstruct a weekly history of water δ18O, and with the observed river discharge vs. water δ18O relation, produce a qualitative record of river discharge. These analytical techniques applied to a historical Brazos River mussel shell collected prior to dam construction reveal weekly records of

  12. A new derivatization method for δ18O analysis of individual carbohydrates with GC-Pyrolysis-IRMS

    Science.gov (United States)

    Lehmann, M. M.; Siegwolf, R. T.; Saurer, M.; Blees, J.; Fischer, M.; Zech, M.

    2015-12-01

    Compound specific isotope analysis (CSIA) with gas chromatography coupled to an isotope ratio mass spectrometer (GC-Pyr-IRMS) is nowadays a powerful tool that is widely used by a broad spectrum of research fields to investigate the isotopic signature of diverse metabolites. While many CSIA methods for carbon, hydrogen, and nitrogen isotopes are known, CSIA methods for the analysis of oxygen isotopes (δ18O) are still not widely established. Especially, reliable and precise methods for the δ18O analyses of individual carbohydrates are scarce, which is caused by the highly sensitive nature of the sugars. However, carbohydrates are important components of living organisms, source for many biochemical reactions, and can be found in all organisms, in soils, sediments, and in air. Thus, a method, allowing the investigation of the 18O/16O ratio in carbohydrates will enhance the scope of research using isotopes. We developed a new and easy to handle derivatization method to determine δ18O in carbohydrates with GC-Pyr-IRMS that consists of a catalyzed one-pot reaction in acetonitrile, resulting in complete methylation of all sugar hydroxyl groups within 24 hours, with silver oxide as the proton acceptor and methyl iodide as the methyl group carrier. Results derived from standard material show unrivalled δ18O precision ranging from about 0.2 to 1.1 ‰ for different individual carbohydrates of different classes and a generally very good accuracy, with a narrow range of 0.2 ‰ around the reference value, despite of high area variations. We applied this method on real samples, demonstrating that the method can commonly be used for analyzing honey samples, and for the analyses of more complex carbohydrate mixtures from plant leaves, including glucose, fructose, pinitol, and sucrose. Our new method may be used for food, beverage, and medical applications, as well as for biogeochemical and paleoclimatic sciences.

  13. Diagenetic overprinting of the sphaerosiderite palaeoclimate proxy: are records of pedogenic groundwater δ18O values preserved?

    Science.gov (United States)

    Ufnar, David F.; Gonzalez, Luis A.; Ludvigson, Greg A.; Brenner, Richard L.; Witzkes, Brian J.

    2004-01-01

    Meteoric sphaerosiderite lines (MSLs), defined by invariant ??18O and variable ??13C values, are obtained from ancient wetland palaeosol sphaerosiderites (millimetre-scale FeCO3 nodules), and are a stable isotope proxy record of terrestrial meteoric isotopic compositions. The palaeoclimatic utility of sphaerosiderite has been well tested; however, diagenetically altered horizons that do not yield simple MSLs have been encountered. Well-preserved sphaerosiderites typically exhibit smooth exteriors, spherulitic crystalline microstructures and relatively pure (> 95 mol% FeCO3) compositions. Diagenetically altered sphaerosiderites typically exhibit corroded margins, replacement textures and increased crystal lattice substitution of Ca2+, Mg2+ and Mn2+ for Fe2+. Examples of diagenetically altered Cretaceous sphaerosiderite-bearing palaeosols from the Dakota Formation (Kansas), the Swan River Formation (Saskatchewan) and the Success S2 Formation (Saskatchewan) were examined in this study to determine the extent to which original, early diagenetic ??18O and ??13C values are preserved. All three units contain poikilotopic calcite cements with significantly different ??18O and ??13C values from the co-occurring sphaerosiderites. The complete isolation of all carbonate phases is necessary to ensure that inadvertent physical mixing does not affect the isotopic analyses. The Dakota and Swan River samples ultimately yield distinct MSLs for the sphaerosiderites, and MCLs (meteoric calcite lines) for the calcite cements. The Success S2 sample yields a covariant ??18O vs. ??13C trend resulting from precipitation in pore fluids that were mixtures between meteoric and modified marine phreatic waters. The calcite cements in the Success S2 Formation yield meteoric ??18O and ??13C values. A stable isotope mass balance model was used to produce hyperbolic fluid mixing trends between meteoric and modified marine end-member compositions. Modelled hyperbolic fluid mixing curves for the

  14. Effect of Cr2O3 on the 18O Tracer Incorporation in SOFC Materials

    Energy Technology Data Exchange (ETDEWEB)

    Finsterbusch, M.; Lussier, A; Negusse, E; Zhu, Z; Smith, R; Schaefer, J; Idzerda, Y

    2010-01-01

    Investigations of the impact of Cr{sub 2}O{sub 3} overlayers on the oxygen self diffusion in two SOFC materials were conducted to gain insight into the Cr poisoning mechanism at the cathode side of solid oxide fuel cells (SOFCs) with stainless steel interconnects. High density Y{sub 0.15}Zr{sub 0.85}O{sub 2} (YSZ) and La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF) sintered pellets were covered with 3 to 30 nm Cr overlayers that were subsequently oxidized, forming Cr{sub 2}O{sub 3}. Standard {sup 18}O tracer diffusion experiments at 800 C were performed and ToF-SIMS profiling revealed that the oxygen ion diffusion coefficients were unaffected by the thin Cr{sub 2}O{sub 3} overlayers, which is predictable since they are a bulk property, but the extracted effective surface exchange coefficients varied with Cr{sub 2}O{sub 3} overlayer thickness. Solid-state reaction measurements and electronic structure considerations concerning the surface exchange, led to the conclusion that the observed oxygen uptake hindrance for Cr{sub 2}O{sub 3} capped LSCF and the slight increase of the surface exchange coefficient for Cr{sub 2}O{sub 3} capped YSZ can be attributed to the electronic properties of Cr{sub 2}O{sub 3}. A critical thickness for Cr{sub 2}O{sub 3} was determined to be 12 nm where the transition from decreasing cathode-performance to a Cr{sub 2}O{sub 3}-property-governed regime occurs.

  15. The 1996 thaw as a {sup 18}O tracer experiment at the lysimeter plant in Wagna; Die Schneeschmelze 1996 als {sup 18}O-Tracerversuch an der Lysimeteranlage in Wagna

    Energy Technology Data Exchange (ETDEWEB)

    Fank, J.; Zojer, H. [Forschungsgesellschaft Joanneum, Graz (Austria). Inst. fuer Geothermie und Hydrogeologie; Stichler, W. [GSF - Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany). Inst. fuer Hydrologie

    1999-02-01

    In the year 1991 a research site was set up in Wagna in the western Leibnitz Field (Styria) which permits an examination of seepage water movement and of material transport as a function of the permeability of the uppermost soil layers and the underlying more coarsly clastic sediments under locale-specific natural management systems. Research at this site is largely based on hydrochemical and isotope-hydrological analysis. The {sup 18}O isotope is an ideal natural tracer of water movement. Infiltration water from the thaw following a snowy winter was displaced downward into the unsaturated zone as a result of a major precipitation event of 85.5 mm from April 2 to 5, 1996. This displacement is evident in the {sup 18}O concentrations of the seepage water at various measuring depths. The displacement is associated with recharge events, thaw processes tending to produce dispersive flows and precipitation events leading to ``piston flow effects. Winter precipitation water reaches a depth of 60 to 70 cm by mid-April. The attenuated {sup 18}O concentration reveals the predominant flow characteristics in the different compartments of the unsaturated zone (finely clastic soils, gravels, and sands). [Deutsch] Im Jahre 1991 wurde in Wagna, im westlichen Leibnitzer Feld (Steiermark), eine Forschungsstation errichtet, die es erlaubt, unter ortsueblichen, natuerlichen Bewirtschaftungssystemen die Sickerwasserbewegung und den Transport von Stoffen in Abhaengigkeit von der Durchlaessigkeit der obersten Bodenschichten und der darunter folgenden groeberklastischen Sedimente vor allem auf Grundlage der hydrochemischen und isotopenhydrologischen Analytik zu untesuchen. Die Verwendung des {sup 18}O-Isotops als natuerlicher Tracer repraesentiert in idealer Weise die Bewegung des Wassers. Infiltrationswasser aus der Schneeschmelze nach einem schneereichen Winter wurde durch ein starkes Niederschlagsereignis von 85.6 mm zwischen 2. und 5. April 1996 in der ungesaettigten Zone

  16. Listening in on the past: what can otolith δ18O values really tell us about the environmental history of fishes?

    Science.gov (United States)

    Darnaude, Audrey M; Sturrock, Anna; Trueman, Clive N; Mouillot, David; Campana, Steven E; Hunter, Ewan

    2014-01-01

    Oxygen isotope ratios from fish otoliths are used to discriminate marine stocks and reconstruct past climate, assuming that variations in otolith δ18O values closely reflect differences in temperature history of fish when accounting for salinity induced variability in water δ18O. To investigate this, we exploited the environmental and migratory data gathered from a decade using archival tags to study the behaviour of adult plaice (Pleuronectes platessa L.) in the North Sea. Based on the tag-derived monthly distributions of the fish and corresponding temperature and salinity estimates modelled across three consecutive years, we first predicted annual otolith δ18O values for three geographically discrete offshore sub-stocks, using three alternative plausible scenarios for otolith growth. Comparison of predicted vs. measured annual δ18O values demonstrated >96% correct prediction of sub-stock membership, irrespective of the otolith growth scenario. Pronounced inter-stock differences in δ18O values, notably in summer, provide a robust marker for reconstructing broad-scale plaice distribution in the North Sea. However, although largely congruent, measured and predicted annual δ18O values did not fully match [ corrected]. Small, but consistent, offsets were also observed between individual high-resolution otolith δ18O values measured during tag recording time and corresponding δ18O predictions using concomitant tag-recorded temperatures and location-specific salinity estimates. The nature of the shifts differed among sub-stocks, suggesting specific vital effects linked to variation in physiological response to temperature. Therefore, although otolith δ18O in free-ranging fish largely reflects environmental temperature and salinity, we counsel prudence when interpreting otolith δ18O data for stock discrimination or temperature reconstruction until the mechanisms underpinning otolith δ18O signature acquisition, and associated variation, are clarified.

  17. Listening in on the past: what can otolith δ18O values really tell us about the environmental history of fishes?

    Directory of Open Access Journals (Sweden)

    Audrey M Darnaude

    Full Text Available Oxygen isotope ratios from fish otoliths are used to discriminate marine stocks and reconstruct past climate, assuming that variations in otolith δ18O values closely reflect differences in temperature history of fish when accounting for salinity induced variability in water δ18O. To investigate this, we exploited the environmental and migratory data gathered from a decade using archival tags to study the behaviour of adult plaice (Pleuronectes platessa L. in the North Sea. Based on the tag-derived monthly distributions of the fish and corresponding temperature and salinity estimates modelled across three consecutive years, we first predicted annual otolith δ18O values for three geographically discrete offshore sub-stocks, using three alternative plausible scenarios for otolith growth. Comparison of predicted vs. measured annual δ18O values demonstrated >96% correct prediction of sub-stock membership, irrespective of the otolith growth scenario. Pronounced inter-stock differences in δ18O values, notably in summer, provide a robust marker for reconstructing broad-scale plaice distribution in the North Sea. However, although largely congruent, measured and predicted annual δ18O values did not fully match [ corrected]. Small, but consistent, offsets were also observed between individual high-resolution otolith δ18O values measured during tag recording time and corresponding δ18O predictions using concomitant tag-recorded temperatures and location-specific salinity estimates. The nature of the shifts differed among sub-stocks, suggesting specific vital effects linked to variation in physiological response to temperature. Therefore, although otolith δ18O in free-ranging fish largely reflects environmental temperature and salinity, we counsel prudence when interpreting otolith δ18O data for stock discrimination or temperature reconstruction until the mechanisms underpinning otolith δ18O signature acquisition, and associated variation, are

  18. Differential cross section measurements of 27Al(p,p/γ)27Al and 27Al(p,αγ)24Mg reactions in the energy range of 1.6-3.0 MeV

    Science.gov (United States)

    Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.; Sharifzadeh, N.; Fathollahi, V.

    2015-11-01

    In this work measurement of differential cross sections of 27Al(p,p/γ)27Al (Eγ = 844, 1014 keV) and 27Al(p,αγ)24Mg (Eγ = 1369 keV) nuclear reactions in the proton energy range of 1.6-3.0 MeV are described and the measured values are presented. Thin Al target was prepared by evaporating a 26 μg/cm2 Al onto a 129 μg/cm2 self-supporting Ag film. The gamma-rays and backscattered protons were detected simultaneously. The gamma-rays and protons were collected by an HPGe detector placed at an angle of 90° with respect to beam direction and an ion implanted Si detector placed at a scattering angle of 165°, respectively. In this experimental setup the great advantage is that differential cross sections could be independent on absolute values of the collected beam charge. The overall systematic uncertainty of cross sections was estimated to be ±9% while statistical errors were less than ±5%.

  19. Sensing Seasonality in the Arabian Sea: a coupled δ18O-Mg/Ca approach

    Directory of Open Access Journals (Sweden)

    W. Feldmeijer

    2014-09-01

    Full Text Available Millennial scale climate variability punctuates the record of Northern Hemisphere glacials in the form of Dansgaard–Oeschger cycles. The coldest episodes within these cycles have a marked impact on the location of the Inter-tropical Convergence Zone and thereby the intensity and extent of the Asian monsoon system. Arabian Sea oceanography is closely linked to the monsoon cycle and responds rapidly to changes therein. Seasonally varying upwelling intensity, adhesive mixing and the resulting variability on sea surface temperature and salinity, however, make it challenging to precisely reconstruct the behaviour of the Indian monsoon system through the Dansgaard–Oeschger cycles. To reconstruct impact of millennial-scale changes in the monsoon on the Arabian Sea, paired single-specimen Mg/Ca and stable oxygen isotope analyses were performed on three species of planktonic foraminifera from the northern as well as the western Arabian Sea. Mismatches between Mg/Ca- and δ18O-derived temperatures reflect changes in salinity caused by regional variability in the hydrological cycle. Comparison of Mg/Ca-derived temperatures from Globigerinoides ruber, Globigerina bulloides and Neogloboquadrina dutertrei over Heinrich Event 4 and Interstadial 8 allows for reconstructing the seasonal range in temperatures (minima and maxima and vertical stratification of the water column during these intervals. Results show that Arabian Sea surface water temperatures were lower during the North Atlantic Heinrich Event 4, and that temperatures in the northern and western Arabian Sea differed relatively much. This implies that the north east monsoon (i.e. boreal winter was enhanced during this interval. In contrast, the summer upwelling related species G. bulloides reveals lower temperatures during Interstadial 8 in the western Arabian Sea, showing an enhanced summer monsoon during the warmers stages of millennial-scale climate variability. Together, these results show that

  20. Reconstructing relative humidity from plant δ18O and δD as deuterium deviations from the global meteoric water line.

    Science.gov (United States)

    Cellulose δ18O and δD in preserved plant material can provide insights on climates and hydrological cycling in the distant past. However, most studies of plant cellulose have used only one isotope, most commonly δ18O, resulting in difficulties partitioning variation between chang...

  1. Re—Examination on the Climatological Significance of the Ice Core δ18O Records from No.1 Glacier at the Head of Urumqi River

    Institute of Scientific and Technical Information of China (English)

    侯书贵

    2000-01-01

    Ice core δ18O recorde from the No.a glacier at the head of the Urumqi River were used o characterize the relationship between δ18O and contemporaneous surface air temperature(Ta) nearby the Daxigou Meteorological Station(3539 m above sea level,-2km away from the ice core drilling site),Although the ice core records of annually averaged δ18O are positively correlated with conemporaneous surface air temperature,especially summer air temperature,the correlation is less significant than that for the precipitation samples due to depositional and post-depositional modification processes,However,the Climatological significance of the ice corδ18O records can be still preserved to a certain degree,which moght extend the application of high altitude and sub-tropical ice core δ18O records to paleoclimate reconstruction.

  2. Climatic significance of δ18O records from an 80.36 m ice core in the East Rongbuk Glacier, Mount Qomolangma (Everest)

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Dongqi; QIN; Dahe; HOU; Shugui; KANG; Shichang; REN

    2005-01-01

    The δ18O variations in an 80.36 m ice core retrieved in the accumulation zone of the East Rongbuk Glacier, Mount Qomolangma (Everest), is not consistent with changes of air temperature from both southern and northern slopes of Himalayas, as well as these of the temperature anomalies over the Northern Hemisphere. The negative relationship between the δ18O and the net accumulation records of the ice core suggests the "amount effect" of summer precipitation on the δ18O values in the region. Therefore, the δ18O records of the East Rongbuk ice core should be a proxy of Indian Summer Monsoon intensity, which shows lower δ18O values during strong monsoon phases and higher values during weak phases.

  3. Integrated platform with a combination of online digestion and (18)O labeling for proteome quantification via an immobilized trypsin microreactor.

    Science.gov (United States)

    Zhang, Shen; Yuan, Huiming; Zhao, Baofeng; Zhou, Yuan; Jiang, Hao; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2015-08-01

    A novel automated integrated platform for quantitative proteome analysis was established with a combination of online digestion of proteins and in situ(18)O labeling by an immobilized enzyme reactor (IMER); digests were captured and desalted by a C18 trap column, and peptides were analyzed by nanoRPLC-ESI-MS/MS. Bovine serum albumin (BSA) was used to evaluate the performance of the developed platform. Compared with traditional offline methods, not only the digestion and labeling time was shortened from 36 h to just 1 h, but also the labeling efficiency was improved from 95% to 99%. Furthermore, the back-exchange from (18)O to (16)O could also be efficiently avoided by the use of IMER. The platform was further evaluated by the quantitative analysis of 100 ng (18)O and (16)O online labeled yeast sample with a mixing ratio of 1 : 1, and the results showed significantly improved sensitivity and reproducibility, as well as improved quantitative accuracy than offline method. With these advantages, the integrated platform was finally applied to the quantitative profiling of 100 ng proteins extracted from two mouse hepatocarcinoma ascites syngeneic cell lines with high and low lymph node metastases rates, and ten differentially expressed proteins were successfully found, most of which were related to tumorigenesis and tumor metastasis. All these results demonstrate that the developed integrated platform can provide a new way for high efficiency (18)O labeling and the quantitative analysis of trace amounts of sample with high accuracy and high reproducibility. PMID:26063120

  4. Oxygen isotopes in tree rings record variation in precipitation δ18O and amount effects in the south of Mexico

    Science.gov (United States)

    Brienen, Roel J W; Hietz, Peter; Wanek, Wolfgang; Gloor, Manuel

    2013-01-01

    [1] Natural archives of oxygen isotopes in precipitation may be used to study changes in the hydrological cycle in the tropics, but their interpretation is not straightforward. We studied to which degree tree rings of Mimosa acantholoba from southern Mexico record variation in isotopic composition of precipitation and which climatic processes influence oxygen isotopes in tree rings (δ18Otr). Interannual variation in δ18Otr was highly synchronized between trees and closely related to isotopic composition of rain measured at San Salvador, 710 km to the southwest. Correlations with δ13C, growth, or local climate variables (temperature, cloud cover, vapor pressure deficit (VPD)) were relatively low, indicating weak plant physiological influences. Interannual variation in δ18Otr correlated negatively with local rainfall amount and intensity. Correlations with the amount of precipitation extended along a 1000 km long stretch of the Pacific Central American coast, probably as a result of organized storm systems uniformly affecting rainfall in the region and its isotope signal; episodic heavy precipitation events, of which some are related to cyclones, deposit strongly 18O-depleted rain in the region and seem to have affected the δ18Otr signal. Large-scale controls on the isotope signature include variation in sea surface temperatures of tropical north Atlantic and Pacific Ocean. In conclusion, we show that δ18Otr of M. acantholoba can be used as a proxy for source water δ18O and that interannual variation in δ18Oprec is caused by a regional amount effect. This contrasts with δ18O signatures at continental sites where cumulative rainout processes dominate and thus provide a proxy for precipitation integrated over a much larger scale. Our results confirm that processes influencing climate-isotope relations differ between sites located, e.g., in the western Amazon versus coastal Mexico, and that tree ring isotope records can help in disentangling the processes

  5. Temperature evolution from the δ18O record of Hani peat, Northeast China, in the last 14000 years

    Institute of Scientific and Technical Information of China (English)

    HONG Bing; LIU CongQiang; LIN QingHua; Shibata YASUYUKI; LENG XueTian; WANG Yu; ZHU YongXuan; HONG YeTang

    2009-01-01

    From the last deglaclation to the Holocene, the Greenland Ice Core (GISP2) δ18O records as well as the records of ice-rafted debris on the surface of the North Atlantic have revealed a succession of sudden cooling events on the centennial to millennial scales. However, the temperature proxy records are rarely studied systematically and directly to ensure that this air temperature cooling pattern simulta- neously existed in the East Asian Region, in addition to the repeated pattern occurring in the Greater Atlantic Region. A peat cellulose δ18O temperature proxy record proximately existing for 14000 years was picked up from the Hani peat in Jilin Province, China. It suggests by comparison that the sudden cooling events, such as the Older Dryas, Inter-Aller(o)d, Younger Dryas, and nine ice-rafted debris events of the North Atlantic, are almost entirely reiterated in the temperature signals of Hani peat cellulose δ18O. These cooling events show that the repeatedly occurring temperature cooling pattern not only appeared in the North Atlantic Region in the high latitudes, but also in the Northwest Pacific Region in the middle latitudes. The climate change events marking the start of the Holocene Epoch, the Holocene Megathermal, the "8.2 kyr" event, the "4.2 kyr" event, the Medieval Warm Period, and the Little Ice Age are further discussed. The sensitivity response of Hani peat cellulose δ18O to the land surface tem- perature and the reason for the age accuracy of peat cellulose 14C are also discussed based on the characteristics of the peat bog environment.

  6. Temperature evolution from the δ 18O record of Hani peat, Northeast China, in the last 14000 years

    Institute of Scientific and Technical Information of China (English)

    Shibata; YASUYUKI

    2009-01-01

    From the last deglaciation to the Holocene, the Greenland Ice Core (GISP2) δ 18O records as well as the records of ice-rafted debris on the surface of the North Atlantic have revealed a succession of sudden cooling events on the centennial to millennial scales. However, the temperature proxy records are rarely studied systematically and directly to ensure that this air temperature cooling pattern simultaneously existed in the East Asian Region, in addition to the repeated pattern occurring in the Greater Atlantic Region. A peat cellulose δ 18O temperature proxy record proximately existing for 14000 years was picked up from the Hani peat in Jilin Province, China. It suggests by comparison that the sudden cooling events, such as the Older Dryas, Inter-Allerφd, Younger Dryas, and nine ice-rafted debris events of the North Atlantic, are almost entirely reiterated in the temperature signals of Hani peat cellulose δ 18O. These cooling events show that the repeatedly occurring temperature cooling pattern not only appeared in the North Atlantic Region in the high latitudes, but also in the Northwest Pacific Region in the middle latitudes. The climate change events marking the start of the Holocene Epoch, the Holocene Megathermal, the "8.2 kyr" event, the "4.2 kyr" event, the Medieval Warm Period, and the Little Ice Age are further discussed. The sensitivity response of Hani peat cellulose δ 18O to the land surface temperature and the reason for the age accuracy of peat cellulose 14C are also discussed based on the characteristics of the peat bog environment.

  7. The effect of the East Atlantic pattern on the precipitation δ18O-NAO relationship in Europe

    Science.gov (United States)

    Comas-Bru, L.; McDermott, F.; Werner, M.

    2016-10-01

    The North Atlantic Oscillation (NAO) is known to influence precipitation δ18O (δ18Op) through its control on air temperature and on the trajectory of the westerly winds that carry moisture onto Europe during boreal winters. Hence, paleoclimate studies seeking to reconstruct the NAO can exploit the δ18O signal that is commonly preserved in natural archives such as stalagmites, ice cores, tree rings and lake sediments. However, such reconstructions should consider the uncertainties that arise from non-stationarities in the δ18Op-NAO relationship. Here, new insights into the causes of these temporal non-stationarities are presented for the European region using both observations (GNIP database) and the output of an isotope-enabled general circulation model (ECHAM5-wiso). The results show that, although the East Atlantic (EA) pattern is generally uncorrelated to δ18Op during the instrumental period, its polarity affects the δ18Op-NAO relationship. Non-stationarities in this relationship result from spatial shifts of the δ18Op-NAO correlated areas as a consequence of different NAO/EA combinations. These shifts are consistent with those reported previously for NAO-winter climate variables and the resulting non-stationarities mean that δ18O-based NAO reconstructions could be compromised if the balance of positive and negative NAO/EA states differs substantially in a calibration period compared with the period of interest in the past. The same approach has been followed to assess the relationships between δ18Op and both winter total precipitation and winter mean surface air temperature, with similar results. Crucially, this study also identifies regions within Europe where temporal changes in the NAO, air temperature and precipitation can be more robustly reconstructed using δ18O time series from natural archives, irrespective of concomitant changes in the EA.

  8. Multipolarity analysis for 14C high-energy resonance populated by (18O,16O) two-neutron transfer reaction

    International Nuclear Information System (INIS)

    The 12C(18O,16O)14C reaction at 84 MeV incident energy has been explored up to high excitation energy of the residual nucleus thanks to the use of the MAGNEX spectrometer to detect the ejectiles. In the region above the two-neutron separation energy, a resonance has been observed at 16.9 MeV. A multipolarity analysis of the cross section angular distribution indicates an L = 0 character for such a transition

  9. Advances in processes for PET radiotracer synthesis: Separation of [18F]fluoride from enriched [18O]water

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a powerful scientific and clinical tool for the study and visualization of human physiology that can provide important information about metabolism and diseases such as cancer. At present, [18F]fluorodeoxyglucose ([18F]FDG) is the most frequently used radiotracer for the routine clinical evaluation of malignant tumors in a range of body tissues. FDG synthesis is continuously being developed to improve and simplify the synthetic procedure including the isolation of [18F]fluoride from [18O]water. There are many methods reported in literature for the isolation of [18F]fluoride, including evaporation, coat-capture–elution, the use of cation-exchange resin and electrode trapping. This review article gives an overview of some of the most common methods for the separation of [18F]fluoride ions from [18O]water, highlighting the potential strength of the methods and also problems and weaknesses for synthesis of 18F PET tracers. - Highlights: • New developments in processing of [18F]fluoride from [18O]water are detailed. • Efficient separation is required for dose-on-demand radiopharmaceuticals. • Electrode trapping of [18F]fluoride offers significant advantages for solvent exchange. • Microfluidic devices complement novel technologies for isotope separation and synthesis

  10. 12CO, 13CO and C18O observations along the major axes of nearby bright infrared galaxies

    CERN Document Server

    Tan, Qinghua; Zhang, Zhiyu; Xia, Xiaoyang

    2011-01-01

    We present simultaneous observations of CO,13CO and C18O J=1-0 emission in 11 nearby (cz<1000 km/s) bright infrared galaxies. Both 12CO and 13CO are detected in the centers of all galaxies, except for 13CO in NGC 3031. We have also detected C18O, CS J=2-1, and HCO+ J=1-0 emission in the nuclear regions of M82 and M51. These are the first systematical extragalactic detections of 12CO and its isotopes from the PMO 14m telescope. We have conducted half-beam spacing mapping of M82 over an area of 4'*2.5' and major axis mapping of NGC 3627, NGC 3628, NGC 4631, and M51. The radial distributions of 12CO and 13CO in NGC 3627, NGC 3628, and M51 can be well fitted by an exponential profile. The 12CO/13CO intensity ratio,R,decreases monotonically with galactocentric radius in all mapped sources. The average R in the center and disk of the galaxies are 9.9+/-3.0 and 5.6+/-1.9 respectively, much lower than the peculiar R(~24) found in the center of M82. The intensity ratios of 13CO/C18O, 13CO/HCO+ and 13CO/CS (either o...

  11. Determination of δ2H and δ18O in mineral water based on Cavity Ring-Down Spectrometry

    Science.gov (United States)

    Tonietto, G.; Godoy, J.; Godoy, M. L.

    2013-12-01

    Stable isotopes of water are proven indicators, tracers and recorders of processes that affect the hydrologic cycle. Measurements of the stable isotope ratios (δ2H, δ18O and δ17O) of both liquid water and water vapor are widely used in hydrology, atmospheric sciences, and biogeochemistry to determine the migration of water through an ecosystem. Application of the method to Brazilian bottled mineral water has shown that it is possible to trace the origin of the water to at least the state level within Brazilian geographical regions. National and regional meteoric water lines were constructed with substantial differences between geographical regions, in particular for the central region of the country, with a slope coefficient of approximately seven and no deuterium excess. The repeatability, reproducibility and accuracy of the direct measurement of δ2H and δ18O isotopes in water samples were evaluated using Cavity Ring-Down Spectrometry, and values comparable with the Isotopic Ratio Mass Spectrometry were obtained. Memory effect correction was negligible after five successive injections, and the time for each sample analysis was approximately 7 minutes. The new high throughput method measures isotopologues of water with a typical precision of better than 0.15‰ for δ18O and better than 0.6‰ for δ2H.

  12. Compound-specific delta18O analyses of neutral sugars in soils using GC-Py-IRMS

    Science.gov (United States)

    Zech, Michael; Glaser, Bruno; Werner, Roland; Juchelka, Dieter

    2010-05-01

    Stable oxygen isotopes (delta18O) are a valuable (paleo-)climate proxy applied to ice cores, deep sea sediments, speleothems and lake sediments. For instance, there has been made much effort to assess delta18O of cellulose from lake sediments. However, purity grade of the extracted cellulose and hygroscopy are analytical problems. In order to overcome these problems, we tested compound-specific delta18O analyses of neutral sugars using gas chromatography - pyrolysis - isotope ratio mass spectrometry (GC-Py-IRMS). Although this technique is available for about the last ten years, it is hardly applied so far. We ensured quantitative conversion of organically bound oxygen to CO in the pyrolysis reactor by monitoring not only mass 28 but also mass 44 (CO2) and excluded oxygen contamination in our system by co-analysing oxygen-free compounds (alkanes). Neutral sugars from litter and topsoils were extracted hydrolytically and measured after derivatization with methylboronic acid (MBA) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). Corrections were made using sugar standards measured in alternation with the samples to ensure the ‘principle of identical treatment' and for the hydrolytically introduced and exchangeable carbonyl-oxygen bound to C1 in the alditose sugar molecules. First results are promising for the hemicellulose-derived sugars arabinose and xylose as well as for the microbial-derived sugars fucose and rhamnose. Ongoing work focuses on assessing also cellulose-derived glucose and on the analytical elimination of the carbonyl-oxygen of the sugars.

  13. Directly Measured Clumped Isotope Temperatures From Known And Proposed Paleozoic Glacial Intervals Suggest That Oceans Were Depleted in 18O

    Science.gov (United States)

    Petrizzo, D. A.; Runnegar, B.; Ivany, L.; Young, E. D.

    2011-12-01

    Oceans enriched in 13C are thought to result from atmospheric CO2 drawdown and concomitant global cooling resulting from increased burial of organic matter. We investigated ocean temperatures during two times when the oceans were exceptionally heavy in 13C, the Lau Event of the late Silurian and the Late Paleozoic Ice Age (LPIA), using both δ18O and "directly measured" clumped isotope (Δ47) temperatures. We report a tropical ocean temperature of 16 ± 3°C at the peak of the Lau Event, confirm seasonality at a high-latitude LPIA site, and raise the possibility that some degradation of 13C-18O bonds may be widespread in apparently unaltered carbonates that have seen temperatures higher than 100-150°C. Silurian conodonts from Gotland, Sweden, are almost unaltered (CAI ~ 0) indicating burial temperatures of level requires ocean water to have been depleted in 18O by up to 3-4% (Ivany and Runnegar, 2010). This is consistent with the oxygen isotope composition of the Silurian ocean obtained from clumped isotope temperatures during the Lau Event (-4 to -5%).

  14. Isotopic analyses (18O, 13C, 14C) of two meromictic lakes in the Canadian Arctic Archipelago

    International Nuclear Information System (INIS)

    Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their water by isotopic studies. 18O values reflect the permanent stratification of the water in both lakes. The mixolimnia contain waters with an isotopic signal between -13.16 and -21.98%, coherent with the values for precipitation in these high latitudes. In the chemoclines, the delta18O values increase to -10% concomitantly with a rise in chloride content to 42 g.liter-1. In the monimolimnia, hypersaline waters (up to 2.5 times the salinity of seawater) show negative delta18O values (ca. -.08%). These waters result from brine production during permafrost growth in the watershed, according to a Rayleigh process. 14C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2580 +/- 260 years BP. In Lake Sophia, the deep waters exhibit recent 14C activity that suggests recent infiltration of seawater into the lake basin

  15. Water vapor δ2H and δ18O measurements using off-axis integrated cavity output spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Knohl

    2009-08-01

    Full Text Available We present a detailed assessment of a commercially available water vapor isotope analyzer (WVIA, Los Gatos Research, Inc. for simultaneous in-situ measurements of δ2H and δ18O in water vapor. This method, based on off-axis integrated cavity output spectroscopy, is an alternative to the conventional water trap/isotope ratio mass spectrometry (IRMS techniques. We evaluate the analyzer in terms of precision, memory effects, concentration dependence, temperature sensitivity and long-term stability. A calibration system based on ink jet technology is used to characterize the performance and to calibrate the analyzer. Our results show that the precision at an averaging time of 15 s is 0.16‰ for δ2H and 0.08‰ for δ18O. The isotope ratios are strongly dependent on the water mixing ratio of the air. Taking into account this concentration dependence as well as the temperature sensitivity of the instrument we obtained a long-term stability of the water isotope measurements of 0.38‰ for δ2H and 0.25‰ for δ18O. The accuracy of the WVIA was further assessed by comparative measurements using IRMS and a dew point generator indicating a linear response in isotopic composition and H2O concentrations. The WVIA combined with a calibration system provides accurate high resolution water vapor isotope measurements and opens new possibilities for hydrological and ecological applications.

  16. Factors Influencing the Stable Oxygen and Hydrogen Isotopic Composition (δ 18O and δ D) of a Subarctic Freshwater Lake Ecosystem

    Science.gov (United States)

    Wang, Y.; Wooller, M. J.

    2005-12-01

    Previous studies have shown that the stable oxygen and hydrogen isotopic compositions (δ 18O and δD) in various animal tissues can be used to examine past climates and animal migration pattern. Little attention has been paid to the relative roles of diet and water influencing the overall δ 18O and δD of animal tissues in freshwater ecosystems. It is unclear whether different trophic levels in a freshwater lake ecosystem have an identical relationship to the water that surrounds them. The δ18O and δD values of animal tissues may be controlled by numerous different factors, including metabolic and biosynthetic isotopic fractionation and variations of δ 18O and δD in the food available. We began to examine these issues by analyzing the δ 18O and δD throughout a freshwater aquatic ecosystem at Smith Lake in Alaska. We collected samples representing primary producers and consumers (primary and secondary). Samples included green algae, various aquatic plants, such as Nuphar variegatum (water lily), Polygonum amphibium (water smartweed), Carex utriculata (sedge), Utricularia vulgaris (common bladderwort), Typha latifolia (common cattail), and a range of aquatic invertebrates, including Chironomus. sp (midge), Zygoptera (damselfly), Anisoptera (dragonfly), Dytiscidae (diving beetle) and Euhirudinea (leeches). The δ 18O and δD of Smith Lake water were ~-13.5e and -129.0e, respectively, and we present the δ 18O and δD of the rest of the ecosystem relative to these data. For instance, the δ 18O of chironomus sp. was ~12.1, which is greater than the of the lake water. Preliminary results suggest the extent of the fractionation between δ 18O of chironomids vs. lake water δ 18O is consistent with previous studies. Our data provide an insight into the range of variations that could be expected within a single freshwater ecosystem.

  17. Toward accurate thermochemistry of the {sup 24}MgH, {sup 25}MgH, and {sup 26}MgH molecules at elevated temperatures: Corrections due to unbound states

    Energy Technology Data Exchange (ETDEWEB)

    Szidarovszky, Tamás [MTA-ELTE Research Group on Complex Chemical Systems, P.O. Box 32, H-1518 Budapest 112 (Hungary); Császár, Attila G., E-mail: csaszar@chem.elte.hu [MTA-ELTE Research Group on Complex Chemical Systems, P.O. Box 32, H-1518 Budapest 112 (Hungary); Laboratory on Molecular Structure and Dynamics, Institute of Chemistry, Eötvös University, Pázmány Péter sétány 1/A, H-1117 Budapest (Hungary)

    2015-01-07

    The total partition functions Q(T) and their first two moments Q{sup ′}(T) and Q{sup ″}(T), together with the isobaric heat capacities C{sub p}(T), are computed a priori for three major MgH isotopologues on the temperature range of T = 100–3000 K using the recent highly accurate potential energy curve, spin-rotation, and non-adiabatic correction functions of Henderson et al. [J. Phys. Chem. A 117, 13373 (2013)]. Nuclear motion computations are carried out on the ground electronic state to determine the (ro)vibrational energy levels and the scattering phase shifts. The effect of resonance states is found to be significant above about 1000 K and it increases with temperature. Even very short-lived states, due to their relatively large number, have significant contributions to Q(T) at elevated temperatures. The contribution of scattering states is around one fourth of that of resonance states but opposite in sign. Uncertainty estimates are given for the possible error sources, suggesting that all computed thermochemical properties have an accuracy better than 0.005% up to 1200 K. Between 1200 and 2500 K, the uncertainties can rise to around 0.1%, while between 2500 K and 3000 K, a further increase to 0.5% might be observed for Q{sup ″}(T) and C{sub p}(T), principally due to the neglect of excited electronic states. The accurate thermochemical data determined are presented in the supplementary material for the three isotopologues of {sup 24}MgH, {sup 25}MgH, and {sup 26}MgH at 1 K increments. These data, which differ significantly from older standard data, should prove useful for astronomical models incorporating thermodynamic properties of these species.

  18. Changes in the δ18O and δ30Si values of partially dissolved phytoliths: implications for environmental reconstruction

    Science.gov (United States)

    Prentice, A. J.; Jabeen, I.; Webb, E. A.

    2014-12-01

    The oxygen and silicon isotope compositions of phytolith silica preserved in soils can be used to examine past climate and biogeochemical cycles. The δ18O values of phytoliths vary with temperature and the δ18O values of formation water while the δ30Si values of phytoliths depend on silicon availability and weathering rates. However, further investigation into the stability of opal-A phytoliths in soils is necessary, as post-depositional alteration of biogenic silica may alter the isotopic composition and affect paleoenvironmental reconstruction. The effects of partial dissolution on the oxygen- and silicon-isotope composition of phytoliths was assessed through dissolution experiments in silicic acid-free water at a range of temperature (4-44°C) and pH conditions (4-10). After 3-30% dissolution, concurrent oxygen and silicon isotope analyses were obtained for the remaining opal-A. Over the course of the experiments oxygen and silicon isotope values of solid silica changed by up to +4.4 ‰ and +0.55 ‰, respectively. Under most conditions δ30Si values increased during early dissolution, followed by a decrease as dissolution progressed until δ30Si values were similar to, or in extreme cases, lower than the original unaltered phytoliths. This might indicate that both dissolution and re-precipitation contribute to the isotopic composition of the altered phytoliths. Changes in δ18O values of the phytoliths follow a similar pattern. We propose that the outer, reactive surface of a fresh phytolith is depleted of 30Si and 18O relative to the rest of the sample. A decrease in surface area suggests that removal of this layer accounts for the initial increase in δ30Si and δ18O values during early dissolution. Extended reaction times result in lower isotopic values and an unexpected decease in aqueous Si suggesting precipitation or exchange occurs. This study improves our understanding of the role of terrestrial biogenic silica in global Si cycle. Post

  19. Quantitative Proteomic Analysis of Bromotetrandrine and Tetrandrine in K562 Cell Line Using 18O-labeling Method

    Institute of Scientific and Technical Information of China (English)

    TAN Ying; GE Zhi-qiang; LIU Chang-xiao

    2012-01-01

    Objective To compare quantitative proteomic analysis of bromotetrandrine (W198) which was a Class Ⅰ new antitumor drug in China and tetrandrine (Tet) in K562 cell line using 18O-labeling method.Methods To illustrate its mechanism,a shotgun quantitative proteomic strategy employing 2D LC-MS-MS and trypsin catalyzed 18O-labeling quantification was carried out in this study.Compared to normal chronic leukemia cell line K562 and K562 induced by Tet,the proteomic changes of K562 induced by W198 were investigated.In order to validate the quantitation by the 18O-labeling,the analysis was done on an equivalent sample composed of the same amount of labeled and unlabeled proteins from normally cultured cells to act as a reference to the comparative sample.Results A threshold of ± 2-fold change for deciding whether a protein concentration was changed was settled for the following experiments.Comparing the 105 identified soluble proteins' expression levels of the apoptosis starting up K562 cells after W198 induction with the normally cultured cells,16 proteins were found with significantly altered expression levels after W198 treatment.Eight proteins were up-expressed including HMGB2,peroxiredoxin-2,and eIF4A-I,etc.Eight proteins were down-expressed including TCP-1,GRP94,GST-π,and SFGHs,etc.Compared to K562 induced by Tet,eight proteins of K562 were found with significantly altered expression levels after W198 treatment.Five proteins were up-expressed including HSP 90-β and 40S ribosomal protein S15a,etc.Three proteins were down-expressed including phosphoglycerate kinase 1,isoform 5 of interleukin enhancer-binding factor 3,etc.Conclusion The 18O-labeling MS-MS-based method is ideal as a discovery tool,but it is not suitable for validation using a large number of samples.Other more effective methods,such as Western blotting should be used for further validation of candidate cancer proteins discovered from 18O-labeling samples.In total,105 soluble proteins were discovered

  20. Southwest U.S. Paleoclimate Over the Past 30,000 Years: Insights from Speleothem δ18O and Growth Rate Time Series

    Science.gov (United States)

    Meyer, K. J.; FENG, W.; Banner, J. L.; James, E.; Musgrove, M.

    2011-12-01

    A 30 ky growth rate and high-resolution δ18O time series from a central Texas (TX) speleothem provides new insights when integrated with recently published speleothem δ18O and growth rate records from New Mexico (NM) and Arizona (AZ), along with Gulf of Mexico (GOM) foraminifera δ18O records. This comparison enables a regional assessment of factors which may control temporal variations in rainfall amount and moisture sources in the Southwestern U.S. The three speleothem locations (TX, NM, AZ) span ~ 1,200 km. A regional east-to-west decrease in speleothem δ18O values of up to 9 % is observed throughout the record. This is the same direction of regional decrease as in modern rainfall. This suggests 1) mixing of moisture from two sources, Pacific moisture (low δ18O), and GOM moisture (high δ18O), and 2) that these two sources have contributed moisture to the region for most of the last 30 ky. Prior to 15 ka, relatively large magnitude, millennial-scale oscillations (up to ~3 %) occur in the NM δ18O record while the TX and AZ records show smaller variations (~1 %). Starting at ~ 15 ka, both AZ and NM records show a rapid increase in δ18O values, whereas TX shows a decrease prior to a rapid increase. This dip in the TX δ18O record approximately corresponds with δ18O shifts in the GOM that have been attributed to glacial melt water inputs. All three records show peaks in growth rate between 15 and 12 ka, and significant decreases in growth rate in the Holocene. The speleothem δ18O time series appear to reflect changes in rainfall amount and composition. The correspondence of the TX and GOM records implicates GOM moisture composition as the major control on Late Pleistocene to Holocene TX precipitation δ18O values. NM and AZ, by contrast, apparently received varying proportions of Pacific and GOM sources over this time period. Periods of high δ18O values in the NM and AZ records, when combined with relative high growth rates, may suggest increased overall

  1. Water - Isotope - Map (δ 18O, δ 2H, 3H) of Austria: Applications, Extremes and Trends

    Science.gov (United States)

    Wyhlidal, Stefan; Kralik, Martin; Benischke, Ralf; Leis, Albrecht; Philippitsch, Rudolf

    2016-04-01

    The isotopic ratios of oxygen and hydrogen in water (2H/1H and 18O/16O) are important tools to characterise waters and their cycles. This starts in the atmosphere as rain or snow and continues in surface water and ends in shallow groundwater as well as in deep groundwater. Tritium formed by natural cosmic radiation in the upper atmosphere and in the last century by tests of thermonuclear bombs in the atmosphere, is characterised by its radioactive decay with a half-life of 12.32 years and is an ideal age-marker during the last 60 years. To determine the origin and mean age of waters in many projects concerning water supply, engineering and scientific projects in the last 45 years on more than 1,350 sites, more than 40,000 isotope measurements were performed in Austria. The median value of all sites of oxygen-18 is δ 18O -10.7 ‰ and for hydrogen-2 δ 2H -75 ‰. As the fractionation is mainly temperature dependent the lowest negative values are observed in winter precipitation (oxygen-18 as low as δ 18O -23 ‰) and in springs in the mountain regions (δ 18O -15.1 ‰). In contrast the highest values were observed in summer precipitation (up to δ 18O - 0.5 ‰) and in shallow lakes in the Seewinkel (up to δ 18O + 5 ‰). The isotopic ratios of the Austrian waters are also influenced by the origin of the evaporated water masses. Therefore the precipitation in the region south of the main Alpine crest (East-Tyrol, Carinthia and South-East Styria) is approximately 1 ‰ higher in δ 18O-values than sites at the same altitude in the northern part. This is most probably caused by the stronger influence of precipitation from the mediterranean area. The median value of all 1,120 sampling sites of decay corrected (2015) tritium measurements is 6.2 tritium units (TU). This is somewhat smaller than the median value of all precipitation stations with 7.2 TU. This can be explained by the fact that in most cases in groundwater the median value has been reduced by decay

  2. Warm Tropical Sea Surface Temperatures During the Pliocene: a New Record from Mg/Ca and δ18O In Situ Techniques

    Science.gov (United States)

    Wycech, J.; Kelly, D.; Kozdon, R.; Fournelle, J.; Valley, J. W.

    2013-12-01

    The Pliocene Warm Period (PWP) was a global warming event that punctuated Earth's climate history ~3 Ma, and study of its geologic record is providing important constraints for models predicting future climate change. Many sea surface temperature (SST) reconstructions for the PWP indicate amplified polar warmth with minimal or absent warming in the tropics - a phenomenon termed the cool tropics paradox. Key pieces of evidence for the lack of tropical warmth are oxygen isotope (δ18O) and Mg/Ca ratios in planktic foraminiferal shells. However, the δ18O data used to reconstruct surface-ocean conditions are derived from whole foraminiferal shells with the assumption that their geochemical compositions are well preserved and homogeneous. To the contrary, most planktic foraminiferal shells found in deep-sea sediments are an aggregate mixture of three carbonate phases (18O-depleted pre-gametogenic calcite, 18O-rich gametogenic calcite added during reproduction, and very 18O-rich diagenetic calcite) that formed under different physiological and/or environmental conditions. Here we report preliminary results of an ongoing study that uses secondary ion mass spectrometry (SIMS) and electron probe microanalysis (EPMA) to acquire in situ δ18O and Mg/Ca data, respectively, from 3-10 μm domains within individual planktic foraminiferal shells (Globigerinoides sacculifer) preserved in a PWP record recovered at ODP Site 806 in the West Pacific Warm Pool. SIMS analyses show that the δ18O of gametogenic calcite is 1-2‰ higher than in the pre-gametogenic calcite of Gs. sacculifer. Mass-balance calculations using the mean δ18O of gametogenic and pre-gametogenic calcites predict a whole-shell δ18O that is ~1.9‰ lower than the published whole-shell δ18O for Gs. sacculifer in this same deep-sea section. Removal of 18O-depleted, pre-gametogenic calcite via dissolution cannot fully account for this isotopic offset since the mean δ18O of whole shells (-1.3‰) is higher than that

  3. Statistical Model to Analyze Quantitative Proteomics Data Obtained by 18O/16O Labeling and Linear Ion Trap Mass Spectrometry

    Science.gov (United States)

    Jorge, Inmaculada; Navarro, Pedro; Martínez-Acedo, Pablo; Núñez, Estefanía; Serrano, Horacio; Alfranca, Arántzazu; Redondo, Juan Miguel; Vázquez, Jesús

    2009-01-01

    Statistical models for the analysis of protein expression changes by stable isotope labeling are still poorly developed, particularly for data obtained by 16O/18O labeling. Besides large scale test experiments to validate the null hypothesis are lacking. Although the study of mechanisms underlying biological actions promoted by vascular endothelial growth factor (VEGF) on endothelial cells is of considerable interest, quantitative proteomics studies on this subject are scarce and have been performed after exposing cells to the factor for long periods of time. In this work we present the largest quantitative proteomics study to date on the short term effects of VEGF on human umbilical vein endothelial cells by 18O/16O labeling. Current statistical models based on normality and variance homogeneity were found unsuitable to describe the null hypothesis in a large scale test experiment performed on these cells, producing false expression changes. A random effects model was developed including four different sources of variance at the spectrum-fitting, scan, peptide, and protein levels. With the new model the number of outliers at scan and peptide levels was negligible in three large scale experiments, and only one false protein expression change was observed in the test experiment among more than 1000 proteins. The new model allowed the detection of significant protein expression changes upon VEGF stimulation for 4 and 8 h. The consistency of the changes observed at 4 h was confirmed by a replica at a smaller scale and further validated by Western blot analysis of some proteins. Most of the observed changes have not been described previously and are consistent with a pattern of protein expression that dynamically changes over time following the evolution of the angiogenic response. With this statistical model the 18O labeling approach emerges as a very promising and robust alternative to perform quantitative proteomics studies at a depth of several thousand proteins

  4. Holocene changes in monsoon precipitation in the Andes of NE Peru based on δ18O speleothem records

    Science.gov (United States)

    Bustamante, M. G.; Cruz, F. W.; Vuille, M.; Apaéstegui, J.; Strikis, N.; Panizo, G.; Novello, F. V.; Deininger, M.; Sifeddine, A.; Cheng, H.; Moquet, J. S.; Guyot, J. L.; Santos, R. V.; Segura, H.; Edwards, R. L.

    2016-08-01

    Two well-dated δ18O-speleothem records from Shatuca cave, situated on the northeastern flank of the Peruvian Andes (1960 m asl) were used to reconstruct high-resolution changes in precipitation during the Holocene in the South American Summer Monsoon region (SASM). The records show that precipitation increased gradually throughout the Holocene in parallel with the austral summer insolation trend modulated by the precession cycle. Additionally the Shatuca speleothem record shows several hydroclimatic changes on both longer- and shorter-term time scales, some of which have not been described in previous paleoclimatic reconstructions from the Andean region. Such climate episodes, marked by negative excursions in the Shatuca δ18O record were logged at 9.7-9.5, 9.2, 8.4, 8.1, 5.0, 4.1, 3.5, 3.0, 2.5, 2.1 and 1.5 ka b2k, and related to abrupt multi-decadal events in the SASM. Some of these events were likely associated with changes in sea surface temperatures (SST) during Bond events in the North Atlantic region. On longer time scales, the low δ18O values reported between 5.1-5.0, 3.5-3.0 and 1.5 ka b2k were contemporaneous with periods of increased sediment influx at Lake Pallcacocha in the Andes of Ecuador, suggesting that the late Holocene intensification of the monsoon recorded at Shatuca site may also have affected high altitudes of the equatorial Andes further north. Numerous episodes of low SASM intensity (dry events) were recorded by the Shatuca record during the Holocene, in particular at 10.2, 9.8, 9.3, 6.5, 5.1, 4.9, 2.5 and 2.3 ka b2k, some of them were synchronous with dry periods in previous Andean records.

  5. Temporal variations of the 18O/16O signal of the whole-canopy transpiration in a temperate forest

    Science.gov (United States)

    Lee, Xuhui; Kim, Kyounghee; Smith, Ronald

    2007-09-01

    Biosphere-atmosphere exchange of water vapor isotopes plays an important role in the global atmospheric 18O-CO2 and 18O-O2 budgets. In this paper, we report the results of the first continuous measurements of isotope ratios of water vapor and the evapotranspiration flux in a temperate forest over one full growing season. We found that the 18O/16O isotopic signal of the whole-canopy transpiration (δT) was not in steady state with respect to plant source water. The departure from steady state was greatest at night and on days of low transpiration rates. Relative humidity was an important driver on timescales shorter than a few hours; on the diurnal timescale, the nonsteady state behavior was driven by relative humidity and the covarying transpiration rate. On average, δT was lowest in midmorning and highest at midnight, with an average peak-to-peak variation on the order of 15‰ over the growing season. A diurnal variation of 60‰ or more was observed on some days. On the seasonal timescale, δT was tightly coupled with the precipitation isotope ratio in the early growing season and fluctuated around the isotope ratio of the stem water of overstory trees in the late growing season. The temporal shift suggests that the forest switched its water source from the shallow to the deep soil pool and that the overstory trees dominated the whole stand transpiration in the late growing season. Using isotopic partitioning, we estimated that the overstory trees contributed roughly 70% to the whole-stand transpiration water loss during the growing season.

  6. Comparison of coral δ18O with pseudocorals derived from in situ sea surface salinity and temperature measurements

    Science.gov (United States)

    DeLong, K. L.; Chaichi, N.; Maupin, C. R.; Richey, J. N.; Quinn, T. M.; Poore, R. Z.

    2015-12-01

    Paleoclimatologists use pseudocorals and forward modeling of coral oxygen isotopes (δ18O) to assess δ18O variations for comparison with climate model output in order to understand past tropical oceanic-atmospheric variability. Oxygen isotopic (δ18Ocoral) variability in shallow water coral skeletons is dependent on sea surface temperature (SST) and δ18O of seawater (δ18Osw), which varies with sea surface salinity (SSS). However, measurements of δ18Osw and SSS are sparse; therefore, simulated SSS (e.g., SODA) is typically used in pseudocoral investigations. Our study site is the Dry Tortugas National Park (DRTO; 24º42'N, 82º48'W) in the southeastern Gulf of Mexico (GOM) where hourly SST and SSS measurements are available from NOAA buoys (1992-2002) and the Florida Keys National Marine Sanctuary (FKNMS; 2011-2014). Here we use bivariate forward modeling of monthly average buoy SSS and SST to develop a time series of pseudocoral δ18O (δ18Op = -0.22(‰/ºC)SST + 0.11(‰/psu)SSS) for DRTO that are compared with δ18Ocoral variations from three Siderastrea siderea coral colonies growing in close proximity within the park. We use the relationship for δ18Osw and SSS determined for Flower Garden Banks coral reef in the northern GOM (27º52'N, 93º49'W) since no measurements of δ18Osw are currently available for DRTO. δ18Op co-varies with δ18Ocoral (r2 = 0.59) with a root mean square error (RMSE = 0.32‰) greater than the intercolony δ18Ocoral variability (r2 = 0.80; RSME = 0.07‰). Discrepancies between δ18Op and δ18Ocoral may be related to the lack of a local SSS-δ18Osw relationship for DRTO or uncertainties in subannual time assignment for δ18Ocoral. A new source of SSS is the NASA satellite Aquarius (2012-2014), which may be useful in future pseudocoral studies, that is evaluated along with high resolution simulated SSS (Global Ocean Physics Reanalysis GLORYS2V3; 1993-2012). We find similar correlation between Aquarius-derived SSS and FKNMS SSS (r2

  7. Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

    Science.gov (United States)

    Horton, Travis W.; Defliese, William F.; Tripati, Aradhna K.; Oze, Christopher

    2016-01-01

    Growing pressure on sustainable water resource allocation in the context of global development and rapid environmental change demands rigorous knowledge of how regional water cycles change through time. One of the most attractive and widely utilized approaches for gaining this knowledge is the analysis of lake carbonate stable isotopic compositions. However, endogenic carbonate archives are sensitive to a variety of natural processes and conditions leaving isotopic datasets largely underdetermined. As a consequence, isotopic researchers are often required to assume values for multiple parameters, including temperature of carbonate formation or lake water δ18O, in order to interpret changes in hydrologic conditions. Here, we review and analyze a global compilation of 57 lacustrine dual carbon and oxygen stable isotope records with a topical focus on the effects of shifting hydrologic balance on endogenic carbonate isotopic compositions. Through integration of multiple large datasets we show that lake carbonate δ18O values and the lake waters from which they are derived are often shifted by >+10‰ relative to source waters discharging into the lake. The global pattern of δ18O and δ13C covariation observed in >70% of the records studied and in several evaporation experiments demonstrates that isotopic fractionations associated with lake water evaporation cause the heavy carbon and oxygen isotope enrichments observed in most lakes and lake carbonate records. Modeled endogenic calcite compositions in isotopic equilibrium with lake source waters further demonstrate that evaporation effects can be extreme even in lake records where δ18O and δ13C covariation is absent. Aridisol pedogenic carbonates show similar isotopic responses to evaporation, and the relevance of evaporative modification to paleoclimatic and paleotopographic research using endogenic carbonate proxies are discussed. Recent advances in stable isotope research techniques present unprecedented

  8. 18O isotopic characterisation of non-point source contributed heavy metals (Zn and Cu) contamination of groundwater

    International Nuclear Information System (INIS)

    In many urbanised areas, fast depletion and severe degradation of the of groundwater resource with contaminants such as nitrate, fluoride, and heavy metals is a common phenomenon, resulting in zonal disparity in fresh water availability. Therefore, for protection of groundwater from pollution and depletion, it is a matter of concern for the planners and decision makers to clearly characterise the sources of contamination and to search for an alternative approach for groundwater development and management. In this context, a new approach is presented here, based on monitoring of 18O stable isotopic and heavy metals composition of groundwater, to clearly characterise non-point source contributed heavy metals pollution of groundwater in northern parts of Delhi area. In the investigated area, the Cu content in the groundwater ranges from 3-41 μg/l and Zn content ranges from 5-182 μg/l, showing considerable variation from location to location as well as within the small parts of a location. Wide variation in the 18O stable isotope content of groundwater (δ value of -5.7 per mille to -8.5 per mille) is due to significant variation in the δ18O-contents of rainfall with space and time, as well as intensity and distribution of rainfall. Enrichment in 18O composition with increasing Cu and Zn levels in groundwater suggest that infiltration of rain water, irrigation water and surface run-off water from the surrounding farm lands, along with agrochemicals and other salts present in the soil, to be the main processes causing groundwater contamination. The concentration of Cu and Zn in groundwater vary spatially, due to different degrees of evaporation/recharge, amounts of fertiliser applied and wastes disposed, adsorption/dispersion of species in the soils and lateral mixing of groundwater. Two opposite mechanisms adsorption and redistribution of infiltrating water along with Zn and Cu species in the soil zone are likely to affect the movement of the Zn and Cu species

  9. VizieR Online Data Catalog: C18O/C17O ratios in the Galactic center

    Science.gov (United States)

    Zhang, J. S.; Sun, L. L.; Riquelme, D.; Henkel, C.; Lu, D. R.; Zhang, Y.; Wang, J. Z.; Wang, M.; Li, J.

    2015-09-01

    Our mapping observations of the J=1-0 lines of 12CO, 13 and C17O were carried out with the DLH 13.7m telescope of the Purple Mountain Observatory (PMO) at Delingha in 2011 January and 2012 May and November. The C18O and C17O lines were also observed in single-point mode toward Sgr B2 with the IRAM 30m telescope in 2011 September, and toward Sgr C and Sgr D with the Mopra 22m in 2014 June. (2 data files).

  10. Spatial and temporal characteristics of 2H and 18O in the basin of Dongting Lake. Impact of monsoon precipitation

    International Nuclear Information System (INIS)

    Two water sampling campaigns were carried out in April and August 2012 to investigate the spatial and temporal characteristics of 2H and 18O in the basin of Dongting Lake and to further understand the interactions between precipitation, river water, lake water, and groundwater. Influenced by different monsoons, precipitation, river water, and lake water are enriched in isotopes in April but depleted in August. Stable isotopes of river water and lake water also have great spatial variations. Unlike river and lake water, groundwater has little seasonal isotopic variation, indicating that the transformation between surface water and groundwater is very slow. (author)

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

    OpenAIRE

    Mahendra Kumar Trivedi

    2015-01-01

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

  12. Relationship between δ D and δ18O in precipitation on northand south of the Tibetan Plateau and moisture recycling

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The local meteoric water line (MWL) has been established from north to south of theTibetan Plateau based on the measured results of δD and δ18O in precipitation and river water, andthe relationship between MWL and moisture origins discussed. The spatial and seasonal variationsof d in precipitation and river water on the Tibetan Plateau have been studied. Results show thatthe spatial and seasonal variations of d between north and south of the Tanggula Mountains arerelated to different moisture origins and water recycling

  13. First measurement of the {sup 18}O(p,{alpha}){sup 15}N cross section at astrophysical energies

    Energy Technology Data Exchange (ETDEWEB)

    Cognata, M La; Spitaleri, C; Cherubini, S; Gulino, M; Lamia, L; Pizzone, R G; Puglia, S M R; Rapisarda, G G; Romano, S; Sergi, M L [INFN Laboratori Nazionali del Sud, Catania (Italy); Mukhamedzhanov, A; Tribble, R E; Al-Abdullah, T; Banu, A; Goldberg, V [Cyclotron Institute, Texas A and M University, College Station, TX (United States); Coc, A [CSNSM, CNRS/IN2P3, Universite Paris Sud, Orsay (France); Irgaziev, B [GIK Institute of Engineering Sciences and Technology, Topi, District Swabi, N. W. F. P. (Pakistan); Kiss, G G [ATOMKI, Debrecen (Hungary); Mrazek, J [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Crucilla, V, E-mail: LaCognata@lns.infn.i

    2010-01-01

    The {sup 18}O(p,{alpha}){sup 15}N reaction rate has been deduced by means of the Trojan horse method. For the first time the contribution of the 20 keV resonance has been directly evaluated, giving a value about 35% larger than the one in the literature. Moreover, the present approach has allowed to improve the accuracy by a factor 8.5, as it is based on the measured strength instead of spectroscopic measurements. The contribution of the 90 keV resonance has been also determined, which turned out to be of negligible importance to astrophysics.

  14. Separation of Radium in Reaction of 60 MeV/u ~(18)O with ThO_2

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to obserVe the β-delalyed fission from~(230)Ac~[1],experiments were performed.The 60 MeV/u~(18)O beam with an intensity of about 40 enA was used to irradiate a“radium free”ThO_2 powder target(1.5g/cm~2).The~(230)Ac isotope was produced via the reaction~(232)Th-2P→~(230)Ra[?]~(230)Ac.It is difficult to separate~(230)Ac directly from the reaction products and observe its β-delayed fission in the experiment.We solved the problem

  15. A 6-yr record of stable isotope ratios of hydrogen and oxygen and temperature correlation of δ18O in precipitation from Eastern Hungary

    International Nuclear Information System (INIS)

    Complete text of publication follows. Investigation of past environmental changes might be possible only if we understand the isotopic systematic of modern precipitation using precipitation-linked stable isotope proxies or models. The apparent temperature coefficient Δδ18O/ΔT is important because it is used to calculate some paleotemperature changes, and because it is a basis for validating the accuracy of GCMs. In principle, three relationships can be observed between the isotopic composition of precipitation and local surface air temperature: (1) a spatial relation between the long-term averages of δ18O (δ2H) of precipitation and the local air temperature for different stations; (2) a temporal relation between short-term (seasonal) changes of δ18O (δ2H) and temperature for a single station or group of stations and (3) a temporal relation between long-term changes in δ18O (δ2H) and temperature at a certain location. The isotopic composition of hydrogen and oxygen of the monthly precipitation from Eastern Hungary was analyzed in samples collected during a monitoring period from the beginning of 2001 to the end of 2006. At the same time an event-based sample collection and data analysis were also performed. During the studied period, the δ18O values varied from 3.9 to -21.3 per mille and the δ2H values from 2.0 to -176.3 per mille. The composite monthly isotopic ratios of oxygen and hydrogen yield a regression line δ2H = 6.9δ18O - 4.1 per mille with a correlation coefficient of 0.92, while the LMWL calculated on event-based sample δ2H and δ18O values gives a regression line δ2H = 6.6δ18O - 9.1 per mille with a correlation coefficient of 0.90. Both lines are close to the GMWL but show the effect of secondary evaporation. The highest δ2H and δ18O values were obtained during the summer months, whereas the lowest δ2H and δ18O values were recorded during autumn and winter. Time series of δ2H and δ18O values for individual samples, amount

  16. Mean proloculus size, delta super(13) C and delta super(18) O variations in recent benthic foraminifera from the west coast of India and their climatic implications

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Sarkar, A.

    variabilities in delta super(18) O and delta super(13) C are rather high which may be due to disequilibrium isotopic fractionation or probably partial selection of specimens. Climatic implications of the results are discussed and few recommendations are also...

  17. Large-Scale Multiplexed Quantitative Discovery Proteomics Enabled by the Use of an 18O-Labeled “Universal” Reference Sample

    OpenAIRE

    Qian, Wei-Jun; Liu, Tao; Petyuk, Vladislav A; Gritsenko, Marina A.; Petritis, Brianne O.; Polpitiya, Ashoka D.; Kaushal, Amit; Xiao, Wenzhong; Finnerty, Celeste C.; Jeschke, Marc G.; Jaitly, Navdeep; Monroe, Matthew E.; Moore, Ronald J.; Moldawer, Lyle L; Davis, Ronald W

    2009-01-01

    The quantitative comparison of protein abundances across a large number of biological or patient samples represents an important proteomics challenge that needs to be addressed for proteomics discovery applications. Herein, we describe a strategy that incorporates a stable isotope 18O-labeled ″universal″ reference sample as a comprehensive set of internal standards for analyzing large sample sets quantitatively. As a pooled sample, the 18O-labeled ″universal″ reference sample is spiked into e...

  18. Dense Cores of Dark Clouds. XII. 13CO and C18O in Lupus, Corona Australis, Vela, and Scorpius

    Science.gov (United States)

    Vilas-Boas, J. W. S.; Myers, P. C.; Fuller, G. A.

    2000-04-01

    More than 110 dense condensations of the dark clouds in Lupus, Corona Australis, Norma, Vela, and Scorpius were observed in the 13CO and C18O (J=1-0) transitions. The condensations of dark clouds with high star formation activity like the Ophiuchus, Taurus, and Cepheus have average C18O and H2 column densities of 1.8x1015 and 1.1x1022 cm-2. If we take the average size of the condensations to be 0.2 pc, a condensation must have average H2 volumetric densities >=2x104 cm-3 in order to be a good candidate to form stars. The four Lupus filaments have similar radial velocities and velocity dispersions, suggesting that they originated from the same parental cloud. Among these filaments, Lupus 1 is unique in having recent star formation activity, despite the high number of T Tauri stars observed toward the others. Lupus 1 also shows a complex velocity gradient along its main axis. The distribution of radial velocities of the condensations observed toward Scorpius are in good agreement with the hypothesis that they are in a region with expansion velocity smaller than or equal to 18 km s-1. The Corona Australis cloud has velocity gradients ranging from -0.5 km s-1 pc-1 at one extreme to 0.1 km s-1 pc-1 at the other.

  19. Quantitative Proteomic Analysis of Mouse Embryonic Fibroblasts and Induced Pluripotent Stem Cells Using 16O /18O labeling

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xin; Tian, Changhai; Liu, Miao; Wang, Yongxiang; Tolmachev, Aleksey V.; Sharma, Seema; Yu, Fang; Fu, Kai; Zheng, Jialin; Ding, Shi-Jian

    2012-04-06

    Induced pluripotent stem cells (iPSC) hold great promise for regenerative medicine as well as for investigations into the pathogenesis and treatment of various diseases. Understanding of key intracellular signaling pathways and protein targets that control development of iPSC from somatic cells is essential for designing new approaches to improve reprogramming efficiency. Here we report the development and application of an integrated quantitative proteomics platform for investigating differences in protein expressions between mouse embryonic fibroblasts (MEF) and MEF-derived iPSC. This platform consists of 16O/18O labeling, multidimensional peptide separation coupled with tandem mass spectrometry, and data analysis with UNiquant software. Using this platform a total of 2,481 proteins were identified and quantified from the 16O/18O-labeled MEF-iPSC proteome mixtures with a false discovery rate of 0.01. Among them, 218 proteins were significantly upregulated, while 247 proteins were significantly downregulated in iPSC compared to MEF. Many nuclear proteins, including Hdac1, Dnmt1, Pcna, Ccnd1, Smarcc1, and subunits in DNA replication and RNA polymerase II complex were found to be enhanced in iPSC. Protein network analysis revealed that Pcna functions as a hub orchestrating complicated mechanisms including DNA replication, epigenetic inheritance (Dnmt1) and chromatin remodeling (Smarcc1) to reprogram MEF and maintain stemness of iPSC.

  20. Quantitative analysis of cell surface membrane proteins using membrane-impermeable chemical probe coupled with 18O labeling

    Science.gov (United States)

    Zhang, Haizhen; Brown, Roslyn N.; Qian, Wei-Jun; Monroe, Matthew E.; Purvine, Samuel O.; Moore, Ronald J.; Gritsenko, Marina A.; Shi, Liang; Romine, Margaret F; Fredrickson, James K.; Paša-Tolić, Ljiljana; Smith, Richard D.; Lipton, Mary S.

    2010-01-01

    We report a mass spectrometry-based strategy for quantitative analysis of cell surface membrane proteome changes. The strategy includes enrichment of surface membrane proteins using a membrane-impermeable chemical probe followed by stable isotope 18O labeling and LC-MS analysis. We applied this strategy for enriching membrane proteins expressed by Shewanella oneidensis MR-1, a gram-negative bacterium with known metal-reduction capability via extracellular electron transfer between outer membrane proteins and extracellular electron receptors. LC/MS/MS analysis resulted in the identification of about 400 proteins with 79% of them being predicted to be membrane localized. Quantitative aspects of the membrane enrichment were shown by peptide level 16O and 18O labeling of proteins from wild-type and mutant cells (generated from deletion of a type II secretion protein, GspD) prior to LC-MS analysis. Using a chemical probe labeled pure protein as an internal standard for normalization, the quantitative data revealed reduced abundances in ΔgspD mutant cells of many outer membrane proteins including the outer membrane c-cype cytochromes OmcA and MtrC, in agreement with previously investigation demonstrating that these proteins are substrates of the type II secretion system. PMID:20380418

  1. Global isoscapes for δ18O and δ2H in precipitation: improved prediction using regionalized climatic regression models

    Science.gov (United States)

    Terzer, S.; Wassenaar, L. I.; Araguás-Araguás, L. J.; Aggarwal, P. K.

    2013-11-01

    A regionalized cluster-based water isotope prediction (RCWIP) approach, based on the Global Network of Isotopes in Precipitation (GNIP), was demonstrated for the purposes of predicting point- and large-scale spatio-temporal patterns of the stable isotope composition (δ2H, δ18O) of precipitation around the world. Unlike earlier global domain and fixed regressor models, RCWIP predefined 36 climatic cluster domains and tested all model combinations from an array of climatic and spatial regressor variables to obtain the best predictive approach to each cluster domain, as indicated by root-mean-squared error (RMSE) and variogram analysis. Fuzzy membership fractions were thereafter used as the weights to seamlessly amalgamate results of the optimized climatic zone prediction models into a single predictive mapping product, such as global or regional amount-weighted mean annual, mean monthly, or growing-season δ18O/δ2H in precipitation. Comparative tests revealed the RCWIP approach outperformed classical global-fixed regression-interpolation-based models more than 67% of the time, and clearly improved upon predictive accuracy and precision. All RCWIP isotope mapping products are available as gridded GeoTIFF files from the IAEA website (www.iaea.org/water) and are for use in hydrology, climatology, food authenticity, ecology, and forensics.

  2. Global isoscapes for δ18O and δ2H in precipitation: improved prediction using regionalized climatic regression models

    Directory of Open Access Journals (Sweden)

    S. Terzer

    2013-06-01

    Full Text Available A Regionalized Climatic Water Isotope Prediction (RCWIP approach, based on the Global Network for Isotopes in Precipitation (GNIP, was demonstrated for the purposes of predicting point- and large-scale spatiotemporal patterns of the stable isotope compositions of water (δ2H, δ18O in precipitation around the world. Unlike earlier global domain and fixed regressor models, RCWIP pre-defined thirty-six climatic cluster domains, and tested all model combinations from an array of climatic and spatial regressor variables to obtain the best predictive approach to each cluster domain, as indicated by RMSE and variogram analysis. Fuzzy membership fractions were thereafter used as the weights to seamlessly amalgamate results of the optimized climatic zone prediction models into a single predictive mapping product, such as global or regional amount-weighted mean annual, mean monthly or growing-season δ18O/δ2H in precipitation. Comparative tests revealed the RCWIP approach outperformed classical global-fixed regression-interpolation based models more than 67% of the time, and significantly improved upon predictive accuracy and precision. All RCWIP isotope mapping products are available as gridded GeoTIFF files from the IAEA website (www.iaea.org/water and are for use in hydrology, climatology, food authenticity, ecology, and forensics.

  3. Continuous Arctic Ocean Water Vapor Isotope Ratio (δ18O and δ2H) Measurements During a Summer Icebreaker Expedition

    Science.gov (United States)

    Klein, E. S.; Welker, J. M.

    2015-12-01

    Warming in the Arctic is reducing sea ice, which may result in changes to the water cycle through increased atmospheric humidity. Here we present the first continuous record of water vapor isotope ratio (δ18O, δ2H, d-excess) measurements from the sub-Arctic and Arctic Ocean during ship transit through both open water and sea ice. As water vapor isotopes were collected across a spectrum of sea ice conditions, the influence of sea ice and availability of open water moisture sources on Arctic Ocean water vapor isotope values (particularly d-excess) is examined. Isotope values reveal characteristics about water availability at vapor sources, as influenced by presence of sea ice (e.g., ice covered arid or open water humid sources), and air parcel trajectory. Higher d-excess values were generally associated with more northern Arctic, ice covered, and arid vapor sources. Conversely, lower d-excess values were related to more southern, open water, and humid vapor sources. Additionally, water vapor isotopes while sea ice was present were generally characterized by more depleted δ18O and δ2H and higher d-excess values, relative to open water values. These water vapor isotope values also present information about potential shifts in moisture sources in an increasingly ice free Arctic Ocean. Understanding these shifts is important to learning about both modern and past patterns of Arctic atmospheric water movement and distribution.

  4. Conodont apatite δ18O signatures indicate climatic cooling as a trigger of the Late Devonian mass extinction

    Science.gov (United States)

    Joachimski, Michael M.; Buggisch, Werner

    2002-08-01

    The oxygen isotopic composition of conodont apatite from two Frasnian-Famennian boundary sections was measured in order to reconstruct variations in marine paleotemperatures during the late Frasnian mass-extinction event. The measured conodont apatite δ18O values reveal two positive excursions with maximum amplitudes of +1‰ to +1.5‰ that parallel positive excursions in the carbonate carbon isotopic composition. The +3‰ excursions in carbonate δ13C have been interpreted as consequences of enhanced organic carbon burial rate resulting in a decrease in atmospheric CO2 concentration. Climatic cooling as a potential consequence of lower atmospheric CO2 concentration is confirmed by the conodont apatite δ18O records, which translate into cooling of low-latitude surface waters by 5 7 °C. Repeated cooling of the low latitudes during the late Frasnian had a severe impact on the tropical shallow-water faunas that were probably adapted to warm surface-water temperatures and severely affected during the late Frasnian crisis. These prominent variations in ocean-water temperature were stressful to the tropical shallow-water fauna and potentially culminated in low origination rates of new species, one of the major factors of the decline in diversity during the latest Frasnian.

  5. Protostellar accretion traced with chemistry: Comparing synthetic C18O maps of embedded protostars to real observations

    CERN Document Server

    Frimann, Søren; Padoan, Paolo; Haugbølle, Troels

    2015-01-01

    Context: Understanding how protostars accrete their mass is a central question of star formation. One aspect of this is to try and understand if the time evolution of accretion rates in deeply embedded objects is best characterised by a smooth decline from early to late stages, or by intermittent bursts of high accretion. Aims: We create synthetic observations of deeply embedded protostars in a large numerical simulation of a molecular cloud, which are compared directly to real observations. The goal is to compare episodic accretion events in the simulation to observations, and to test the methodology used for analysing the observations. Methods: Simple freeze-out and sublimation chemistry is added to the simulation, and synthetic C18O line cubes are created for a large number of simulated protostars. The spatial extent of C18O is measured for the simulated protostars, and compared directly to a sample of 16 deeply embedded protostars observed with the Submillimeter Array. If CO is distributed over a larger a...

  6. Isotopic analyses (18O, 13C, 14C) of two meromictic lakes in the Canadian Arctic Archipelago

    International Nuclear Information System (INIS)

    Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their waters by isotopic studies. The sigma/sub SMOW/18O values reflect the permanent stratification of the waters in both lakes. The mixolimnia contain waters with an isotopic signal between -13.16 and -2.198%, coherent with the values of precipitation in these high latitudes. The short residence time of the water in this layer makes it possible to record episodic variations of the freshwater inputs to the lakes. In the chemoclines, the sigma18O values increase to -10% concomitantly with a rise in chloride content to 42 g liter-1. This corresponds to a conservative mixing of surficial and deep waters. In the monimolimnia, hypersaline waters from brine production during permafrost growth in the watershed, according to a Rayleigh process. The brines drained toward the deepest part of each lake, after postglacial uplift, and became isolated. 14C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2580 +/- 260 years B.P. In Lake Sophia, the deep waters exhibit recent 14C activity (121.4% modern carbon) that suggests recent infiltration of seawater into the lake basin

  7. Study of some excited states in 21Ne-21Na, 18O-18F and 15N-15O nuclei

    International Nuclear Information System (INIS)

    The study of 21Ne-21Na, 18O-18F and 15N-15O nuclei was performed through proton capture and transfer reactions and allows to determine the spins and parities of some excited states, give the gamma deexcitation schemes of these levels, compute the neutron and proton reduced width γ2sub(n) and γ2sub(p). The levels studied are: in 21Na 4.1520Ne(p,p), (p,p'), (p,p'γ) and (pγ) reactions) and in 21Ne: E(exc)=4.73, 5.69 and 5.78 MeV (20Ne (p,p) reaction); in 18O: E(exc)17O(d,p) reaction); in 15O: 8.92 MeV doublet and 8.98 MeV level (angular correlation 14N(p,γγ) and in 15N: 9.0514N(d,p) reaction). A comparison with theoretical results is discussed and analog states are pointed out

  8. The comparison of H$_2$CO (1$_{10}$--1$_{11}$), C$^{18}$O (1--0) and continuum towards molecular clouds

    CERN Document Server

    Di Tang, Xin; Zhou, Jian Jun; Wu, Gang; Okoh, Daniel

    2014-01-01

    We present large scale observations of C$^{18}$O (1--0) towards four massive star forming regions for MON R2, S156, DR17/L906 and M17/M18. The transitions of H$_2$CO (1$_{10}$--1$_{11}$), C$^{18}$O (1--0) and 6 cm continuum were compared towards the four regions. Analysis of observation and Non--LTE model results shows that the brightness temperature of the formaldehyde absorption line is strongest in background continuum temperature range of about 3 -- 8 K. The excitation of the H$_2$CO absorption line is affected by strong background continuum emission. From the comparison of H$_2$CO and C$^{18}$O maps, we found that the extent of H$_2$CO absorption is broader than that of C$^{18}$O emission in the four regions. Except for the DR17 region, the H$_2$CO absorption maximum is located at the same position with the C$^{18}$O peak. The good correlation between intensities and widths of H$_2$CO absorption and C$^{18}$O emission lines indicate that the H$_2$CO absorption line can trace dense and warm regions of the...

  9. Strong coupling of centennial-scale changes of Asian monsoon and soil processes derived from stalagmite δ18O and δ13C records, southern China

    Science.gov (United States)

    Liu, Dianbing; Wang, Yongjin; Cheng, Hai; Edwards, R. Lawrence; Kong, Xinggong; Li, Ting-Yong

    2016-05-01

    The paleoclimate application of speleothem δ13C is influenced by site-specific processes. Here we present four stalagmite δ13C records from two caves in southern China, covering early and late Marine Isotope Stage (MIS) 3 and the Holocene, to investigate the spatio-temporal pattern of calcite δ13C changes and the relationship with Asian monsoon (AM) variability. In each growth period, precessional- to millennial-scale changes are clear in the δ18O record. In contrast, millennial variability is absent in the δ13C record, which characterizes persistent centennial oscillations. However, centennial-scale δ18O variations agree well with those of δ13C, with a larger amplitude in δ13C changes (about twice that of δ18O). This suggests that soil humidity balance associated with regional hydrological circulations is important for these centennial δ13C changes, although evaporation-related kinetic fractionation can induce concurrent enrichments in δ18O and δ13C. In frequency, the detrended δ18O and δ13C records are coupled at a periodicity of about 300 yr during the last glacial period and 150 yr during the Holocene. Those centennial-scale δ13C variations are generally consistent with Greenland temperature variability, indicating a climate response over broad regions. Thus, strong co-variation of δ18O and δ13C records should have a climatic origin, even if it is amplified by kinetic effects.

  10. 13CO and C18O emission from a dense gas disk at z=2.3: abundance variations, cosmic rays and the initial conditions for star formation

    CERN Document Server

    Danielson, A L R; Smail, Ian; Bayet, E; van der Werf, Paul P; Cox, P; Edge, A C; Henkel, C; Ivison, R J

    2013-01-01

    We analyse the SLEDs of 13CO and C18O for the J=1-0 up to J=7-6 transitions in the gravitationally lensed ultraluminous infrared galaxy SMMJ2135-0102 at z=2.3. This is the first detection of 13CO and C18O in a high-redshift star-forming galaxy. These data comprise observations of six transitions taken with PdBI and we combine these with 33GHz JVLA data and our previous 12CO and continuum emission information to better constrain the properties of the ISM within this system. We study both the velocity-integrated and kinematically decomposed properties of the galaxy and coupled with an LVG model we find that the star-forming regions in the system vary in their cold gas properties. We find strong C18O emission both in the velocity-integrated emission and in the two kinematic components at the periphery of the system, where the C18O line flux is equivalent to or higher than the 13CO. We derive an average velocity-integrated flux ratio of 13CO/C18O~1 suggesting a [13CO]/[C18O] abundance ratio at least 7x lower than...

  11. Laser-based, in situ measurements of fine-scale variations in the [delta][sup 18]O values of hydrothermal quartz

    Energy Technology Data Exchange (ETDEWEB)

    Conrad, M.E.; Chamberlain, C.P. (Dartmouth College, Hanover, NH (United States))

    1992-09-01

    Recently developed laser-based techniques have been used to make in situ measurements of the [delta][sup 18]O values of hydrothermal vein quartz from the Tayoltita and Guanajuato mining districts of Mexico. The [delta][sup 18]O[sub qtz] values within a single 2 [times] 5 cm sample of banded quartz from Guanajuato varied from 12.6[per thousand] to 17.3[per thousand]. Similarly, [delta][sup 18]O[sub qtz] values measured in a 2 [times] 3 cm sample from Tayoltita ranged from 5.7[per thousand] to 9.5[per thousand]. In both cases, the spread of [delta][sup 18]O values measured within individual samples is comparable to the total ranges of [delta][sup 18]O values previously reported for vein samples from the respective districts. Fluid-inclusion homogenization temperatures measured for these samples rule out the possibility that the changes in the [delta][sup 18]O values observed could have been caused by temperature fluctuations; therefore, they must be the result of large shifts in the isotopic composition of the vein fluids.

  12. Contributions of evaporation, isotopic non-steady state transpiration and atmospheric mixing on the delta18O of water vapour in Pacific Northwest coniferous forests.

    Science.gov (United States)

    Lai, Chun-Ta; Ehleringer, James R; Bond, Barbara J; Paw U, Kyaw Tha

    2006-01-01

    Changes in the 2H and 18O of atmospheric water vapour provide information for integrating aspects of gas exchange within forest canopies. In this study, we show that diurnal fluctuations in the oxygen isotope ratio (delta 18O) as high as 4% per hundred were observed for water vapour (delta (18)Ovp) above and within an old-growth coniferous forest in the Pacific Northwest region of the United States. Values of delta 18Ovp decreased in the morning, reached a minimum at midday, and recovered to early-morning values in the late afternoon, creating a nearly symmetrical diurnal pattern for two consecutive summer days. A mass balance budget was derived and assessed for the 18O of canopy water vapour over a 2-d period by considering the 18O-isoflux of canopy transpiration, soil evaporation and the air entering the canopy column. The budget was used to address two questions: (1) do delta 18O values of canopy water vapour reflect the biospheric influence, or are such signals swamped by atmospheric mixing? and (2) what mechanisms drive temporal variations of delta 18Ovp? Model calculations show that the entry of air into the canopy column resulted in an isotopically depleted 18O-isoflux in the morning of day 1, causing values of delta 18Ovp, to decrease. An isotopically enriched 18O-isoflux resulting from transpiration then offset this decreased delta 18Ovp later during the day. Contributions of 18O-isoflux from soil evaporation were relatively small on day 1 but were more significant on day 2, despite the small H2(16)O fluxes. From measurements of leaf water volume and sapflux, we determined the turnover time of leaf water in the needles of Douglas-fir trees as approximately 11 h at midday. Such an extended turnover time suggests that transpiration may not have occurred at the commonly assumed isotopic steady state. We tested a non-steady state model for predicting delta 18O of leaf water. Our model calculations show that assuming isotopic steady state increased isoflux of

  13. How the Pyrenees influence the δ18O and δD compositions of rain and rivers?

    Science.gov (United States)

    Huyghe, Damien; Mouthereau, Frederic; Sebilo, Mathieu; Segalen, Loic

    2016-04-01

    Documenting Earth surface past elevation is critical to understand the dynamics of collisional domains and to investigate tectonics vs. climate interactions and their relative influence on erosion and sedimentation. Topography exerts a direct control on precipitation and it is possible to determine the paleoelevation of a mountain range from analyses of minerals created from paleorainfall, because the isotopic composition of rain (δ18O & δD) decreases with elevation. Topography modifies the patterns of atmospheric circulation and thus the local isotopic lapse rate and the resulting isotope-in-precipitation patterns at high elevation. Thus, before reconstructing paleoelevation, the local modern isotope lapse rate has to be documented to quantify the amount of orographic effect on precipitation and get a first-order understanding of the interactions of topography and rainfall in the study area. Here, we characterize the modern isotope lapse rate in the Pyrenees, a well-know collisional orogen, which is a privileged area for paleotopographic investigations. It presents the advantage to be a small orogen, with mean maximum elevation of ~3000 m, which allows for a reliable and large sampling. We sampled streams and creeks from small catchments that integrate near-surface runoff (i.e., precipitation) over months to years and hence provide a time-averaged signal of elevation. We collected 100 samples in 9 different valleys from N and S Pyrenees during the dry season (August and July), because it is the period during which groundwater, which is comprised by a mixture of rainfall of the annual cycle, dominates the stream water budget. Results reveal a good correlation of δ18O vs. δD values and mean δ18O and δD altitudinal gradients of -3.6‰ and -29‰ /km respectively. Distinct areas can be distinguished over the range according to their isotopic features. In particular, the southern Pyrenees exhibit lowers ratios than the north, suggesting an orographic effect of

  14. Determination of the δ15N and δ18O of nitrate in water; RSIL lab code 2900

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

    2007-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2900 is to determine the δ15N and δ18O of nitrate (NO3-) in water. The δ15N and δ18O of the dissolved NO3- are analyzed by converting the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of the NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

  15. {sup 18}O, {sup 2}H and {sup 3}H isotopic composition of precipitation and shallow groundwater in Olkiluoto

    Energy Technology Data Exchange (ETDEWEB)

    Hendriksson, N. [Geological Survey of Finland, Espoo (Finland); Karhu, J.; Niinikoski, P. [Univ. of Helsinki (Finland)

    2014-12-15

    The isotopic composition of oxygen and hydrogen in local precipitation is a key parameter in the modelling of local water circulation. This study was initiated in order to provide systematic monthly records of the isotope content of atmospheric precipitation in the Olkiluoto area and to establish the relation between local rainfall and newly formed groundwater. During January 2005 - December 2012, a total of 85 cumulative monthly rainfall samples and 68 shallow groundwater samples were collected and the isotopic composition of oxygen and hydrogen was recorded for all those samples. Tritium values are available for 79 precipitation and 65 groundwater samples. Based on the 8-year monitoring, the long-term weighted annual mean isotope values of precipitation and the mean values of shallow groundwater are -11.59 per mille and -11.27 per mille for δ{sup 18}O, - 82.3 per mille and -80.3 per mille for δ{sup 2}H and 9.8 and 9.1 TU for tritium, respectively. Based on these data, the mean stable isotope ratios of groundwater represent the long-term mean annual isotopic composition of local precipitation. The precipitation data were used to establish the local meteoric water line (LMWL) for the Olkiluoto area. The line is formulated as: δ{sup 2}H = 7.45 star δ{sup 18}O + 3.82. The isotope time series reveal a change in time. The increasing trend for the δ{sup 18}O and δ{sup 2}H values may be related to climatic variability while the gradual decline observed in the {sup 3}H data is attributed to the still continuing decrease in atmospheric {sup 3}H activity in the northern hemisphere. The systematic seasonal and long-term tritium trends suggest that any potential ground-level tritium release from the Olkiluoto nuclear power plants is insignificant. The d-excess values of Olkiluoto precipitation during the summer period indicated that a notable amount of re-cycled Baltic Sea water may have contributed to precipitation in the Finnish southern coast. Preliminary estimates

  16. Spring response to precipitation events using δ(18)O and δ(2)H in the Tanour catchment, NW Jordan.

    Science.gov (United States)

    Hamdan, Ibraheem; Wiegand, Bettina; Toll, Mathias; Sauter, Martin

    2016-12-01

    The Tanour spring is one of the several karst springs located in the northern part of Jordan. Water samples from the Tanour spring and precipitation were collected in the area of Ajloun in NW Jordan for the analysis of stable oxygen and hydrogen isotopes to evaluate the spring response to precipitation events. Rainwater and snow samples were collected from different elevations during winters of 2013-2014 and 2014-2015. In addition, spring samples were collected between December 2014 and March 2015. δ(18)O values in rainwater vary from -3.26 to -17.34 ‰ (average: -7.84 ± 3.23 ‰), while δ(2)H values range between -4.4 and -110.4 ‰ (average: -35.7 ± 25.0 ‰). Deuterium excess ranges from 17.8 to 34.1 ‰ (average: 27.1 ± 4.0 ‰). The Local Meteoric Water Line for the study area was calculated to be δ(2)H = 7.66*δ(18)O + 24.43 (R(2) = 0.98). Pre-event spring discharge showed variation in δ(18)O (range -6.29 to -7.17 ‰; average -6.58 ± 0.19 ‰) and δ(2)H values (range -28.8 to -32.7 ‰; average: -30.5 ± 1.0 ‰). In contrast, δ(18)O and δ(2)H rapidly changed to more negative values during rainfall and snowmelt events and persisted for several days before returning to background values. Spring water temperature, spring discharge, and turbidity followed the trend in isotopic composition during and after the precipitation events. The rapid change in the isotopic composition, spring discharge, water temperature, and turbidity in response to recharge events is related to fast water travel times and low storage capacity in the conduit system of the karst aquifer. Based on the changes in the isotopic composition of spring water after the precipitation events, the water travel time in the aquifer is in the order of 5-11 days.

  17. Determination of the δ15N and δ18O of nitrate in solids; RSIL lab code 2897

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

    2007-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2897 is to determine the δ15N and δ18O of nitrate (NO3-) in solids. The NO3- fraction of the nitrogen species is dissolved by water (called leaching) and can be analyzed by the bacterial method covered in RSIL lab code 2900. After leaching, the δ15N and δ18O of the dissolved NO3- is analyzed by conversion of the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

  18. The δ2H and δ18O of tap water from 349 sites in the United States and selected territories

    Science.gov (United States)

    Coplen, Tyler B.; Landwehr, Jurate M.; Qi, Haiping; Lorenz, Jennifer M.

    2013-01-01

    Because the stable isotopic compositions of hydrogen (δ2H) and oxygen (δ18O) of animal (including human) tissues, such as hair, nail, and urine, reflect the δ2H and δ18O of water and food ingested by an animal or a human and because the δ2H and δ18O of environmental waters vary geographically, δ2H and δ18O values of tap water samples collected in 2007-2008 from 349 sites in the United States and three selected U.S. territories have been measured in support of forensic science applications, creating one of the largest databases of tap water δ2H and δ18O values to date. The results of replicate isotopic measurements for these tap water samples confirm that the expanded uncertainties (U = 2μc) obtained over a period of years by the Reston Stable Isotope Laboratory from δ2H and δ18O dual-inlet mass spectrometric measurements are conservative, at ±2‰ and ±0.2 ‰, respectively. These uncertainties are important because U.S. Geological Survey data may be needed for forensic science applications, including providing evidence in court cases. Half way through the investigation, an isotope-laser spectrometer was acquired, enabling comparison of dual-inlet isotope-ratio mass spectrometric results with isotope-laser spectrometric results. The uncertainty of the laser-based δ2H measurement results for these tap water samples is comparable to the uncertainty of the mass spectrometric method, with the laser-based method having a slightly lower uncertainty. However, the δ18O uncertainty of the laser-based method is more than a factor of ten higher than that of the dual-inlet isotoperatio mass spectrometric method.

  19. Formation of low-δ18O magmas of the Kangerlussuaq Intrusion by addition of water derived from dehydration of foundered basaltic roof rocks

    Science.gov (United States)

    Riishuus, Morten S.; Harris, Chris; Peate, David W.; Tegner, Christian; Wilson, J. Richard; Brooks, C. Kent

    2015-05-01

    The Kangerlussuaq Intrusion in East Greenland is concentrically zoned from quartz nordmarkite (quartz syenite) at the margin, through pulaskite, to foyaite (nepheline syenite) in the centre, with no apparent intrusive contacts. The δ18O values of coexisting minerals are consistent with oxygen isotope equilibrium at magmatic temperatures. Most of the intrusion formed from low-δ18O magma; magma δ18O values generally increased upwards from about 3.3 ‰ in the quartz nordmarkites to 5.6 ‰ in the foyaites. The lowest magma δ18O value of about -1.0 ‰ is from the upper part of the nordmarkites, where there is a high concentration of foundered basaltic xenoliths (stoped from the roof of the intrusion). The amphiboles in the syenites have δD values that range from those typical of hydrous mantle-derived minerals to much lower values (-86 to -157 ‰), as do whole-rock samples of xenolith and country rock (-125 to -148 ‰). The low magma δ18O and δD values are consistent with continuous incorporation, exchange and upward escape of low-δ18O and δD fluids released from stoped basaltic roof material. Mass balance suggests that the integrated amount of water involved was 7 wt% of the volume of the magma, but locally reached 30 wt% water. The requirement for large amounts of water with low δ18O value is satisfied only if the foundered basalt contained most of its water in cavities as opposed to hydrous minerals. Even with this requirement, the volume of stoped basalt would have been equal to the volume of the magma. Repeated recharge of the residual magma with progressively less contaminated silica undersaturated melt resulted in a gradual shift across the low-pressure thermal divide. Crystallisation was suppressed by the depression of the liquidus due to water saturation of the residual magma (pH2O ~1 kbar).

  20. Calibration of δ13C and δ18O measurements in CO2 using Off-axis Integrated Cavity Output Spectrometer (ICOS)

    Science.gov (United States)

    Joseph, Jobin; Külls, Christoph

    2014-05-01

    The δ13C and δ18O of CO2 has enormous potential as tracers to study and quantify the interaction between the water and carbon cycles. Isotope ratio mass spectrometry (IRMS) being the conventional method for stable isotopic measurements, has many limitations making it impossible for deploying them in remote areas for online or in-situ sampling. New laser based absorption spectroscopy approaches like Cavity Ring Down Spectroscopy (CRDS) and Integrated Cavity Output Spectroscopy (ICOS) have been developed for online measurements of stable isotopes at an expense of considerably less power requirement but with precision comparable to IRMS. In this research project, we introduce a new calibration system for an Off- Axis ICOS (Los Gatos Research CCIA-36d) for a wide range of varying concentrations of CO2 (800ppm - 25,000ppm), a typical CO2 flux range at the plant-soil continuum. The calibration compensates for the concentration dependency of δ13C and δ18O measurements, and was performed using various CO2 standards with known CO2 concentration and δC13 and δO18 values. A mathematical model was developed after the calibration procedure as a correction factor for the concentration dependency of δ13C and δ18O measurements. Temperature dependency of δ13C and δ18O measurements were investigated and no significant influence was found. Simultaneous calibration of δ13C and δ18O is achieved using this calibration system with an overall accuracy of (~ 0.75±0.24 ‰ for δ13C, ~ 0.81 ±0.26‰ for δ18O). This calibration procedure is found to be appropriate for making Off-Axis ICOS suitable for measuring CO2 concentration and δ13C and δ18O measurements at atmosphere-plant-soil continuum.

  1. Ontogeny and habitat change in Mesozoic cephalopods revealed by stable isotopes ( δ18O, δ13C)

    Science.gov (United States)

    Lukeneder, Alexander; Harzhauser, Mathias; Müllegger, Stefan; Piller, Werner E.

    2010-07-01

    Stable isotope ( δ18O and δ13C) ratios were measured in successive aragonitic shell sequences of ammonoids (class Cephalopoda) to determine whether their depth distributions changed within ontogeny and whether stable isotope values differ in various morphological groups (e.g. Leiostraca vs. Trachyostraca). We concentrate mainly on δ18O for temperature results and added δ13C data to obtain information on the ontogenetic history, for which full spiral measurements were undertaken for the first time. To obtain valid stable isotope data from ammonoid shells, we measured ontogenetic sequences (full shell) within different genera. Data sets from the Jurassic ( Cadoceras) and Cretaceous ( Hypacanthoplites, Nowakites) were chosen due to the pure primary aragonitic shell preservation. The study was designed to extract better information on the habitat and life cycle of fossil cephalopods (e.g. ammonoids) in comparison with recent cephalopods (e.g. Nautilus, Spirula, Sepia) possessing equivalent or comparable hard parts. The data from three genera suggest different modes of life in at least two morphological groups. We detected and established two main groups with different ontogenetic strategies based on the δ18O data. The wcw-type (warm-cool-warm type) of Cadoceras resembles strategies in Nautilus and Sepia, which migrate from shallow into deeper environments and back in ontogeny ( wc-type, warm-cool-type), and the cw-type (cool-warm type) of Hypacanthoplites resembling the first two migration phases of Spirula ( cwc-type), which migrates from deeper into shallower and back again into deeper habitats. The main (three) phases revealed by both δ18O and δ13C data sets most probably reflect diet changes in juvenile to mid-aged individuals, followed by a habitat change for spawning adults. In Cadoceras the temperatures range from 21.2 °C for juveniles down to 12.1 °C for mid-aged individuals and back up 16.9 °C in adults. The cw- type strategy of Hypacanthoplites

  2. Structural and Electronic Properties of Polyoxovanadoborates Containing the [V12B18O60] Core in Different Mixed Valence States

    Directory of Open Access Journals (Sweden)

    Patricio Hermosilla-Ibáñez

    2015-07-01

    Full Text Available This review summarizes all published data until April 2015 related to crystalline lattices formed by the [V12B18O60] core, which generates polyanionic clusters with different degrees of protonation and mixed-valence ratios. The negative charge of this cluster is counterbalanced by different cations such as protonated amines, hydronium, and alkaline, and transition metal ions. The cluster is shown to form extended 1D, 2D, or 3D frameworks by forming covalent bonds or presenting hydrogen bond interactions with the present secondary cations. These cations have little influence on the solid state reflectance UV-visible spectra of the polyanionic cluster, but are shown to modify the FT-IR spectra and the magnetic behavior of the different reported species.

  3. An assessment of the isotopic (2H/18O) integrity of water samples collected and stored by unattended precipitation totalizers

    Science.gov (United States)

    Terzer, Stefan; Wassenaar, Leonard I.; Douence, Cedric; Araguas-Araguas, Luis

    2016-04-01

    The IAEA-WMO Global Network of Isotopes in Precipitation (GNIP) provides worldwide δ18O and δ2H data for numerous hydrological and climatological studies. The traditional GNIP sample collection method relies on weather station operators to accumulate precipitation obtained from manual rain gauges. Over the past decades, widespread weather station automatization resulted in the increased use of unattended precipitation totalizers that accumulate and store the rainwater in the field for up to one month. Several low-tech measures were adopted to prevent in situ secondary evaporative isotopic enrichment (SEE) of totalized water samples (i.e. disequilibrium isotopic fractionation after precipitation is stored in the collection device). These include: (a) adding a 0.5-1 cm floating layer of paraffin oil to the totalizer bottle, (b) using an intake tube leading from the collection funnel and submerged to the bottom of the totalizer bottle, or (c) placing a table tennis ball in the funnel aiming to reduce evaporation of the collected water from the receiving bottle to the atmosphere. We assessed the isotopic integrity of stored rainwater samples for three totalizers under controlled settings: each aforementioned totalizer was filled with a 100 or 500 mL of isotopically known water and installed in the field with the intake funnels sheltered to prevent rainwater collection. Potential evapotranspiration (PET) was obtained from on-site meteorological recordings. Stored evaporative loss from each totalizer was evaluated on a monthly basis; gravimetrically and by analysing δ18O and δ2H of the stored water, for a period of 6 months and a cumulative PET of ˜500 mm. The gravimetric and isotope results revealed that for smaller water volumes (100 ml, corresponding to ca. 5 mm of monthly precipitation), negligible isotope enrichment (δ18O) was observed in the paraffin-oil based totalizer, whereas unacceptable evaporative isotope effects were observed for the ball

  4. Study of 2H and 18O in the Kouris catchment (Cyprus) for the description of the regional groundwater balance

    International Nuclear Information System (INIS)

    The Kouris catchment covers 300 km2 on the southern side of the Troodos Massif of Cyprus and bounded on the South by the Mediterranean Sea. Elevations range from 2000 m to sea level within a distance of 30 km. The basin consists of an ophiolitic complex in the North (ultramafic rocks, gabbros, sheeted dykes and pillow lavas) and an overlying sedimentary complex in the South (chalks, marls, calcarenites and limestones). The ophiolites highly heterogeneous and contain the major groundwater resources in Cyprus. While the geology of the Troodos Massif is very well documented, the hydrogeology of the area is much less known. The aim of this study is to apply 144 new and 72 published analysis of δD and δ18 in groundwater as well as as new and reported in IAEA database analysis of rainfall samples for better understanding of main mechanisms of ground water flow and for checking the assumptions of the groundwater model, developed at the previous stage. 2H and 18O in Precipitation. 2H and 18O contents in rainfall over the Kouris catchment samples are linearly related by the equation of the local meteoric water line: δD = 6.5*δ18 + 10.6 that differs from the equation of the Global Meteoric Water Line by a smaller slope, indicating partial evaporation of rain drops prior to infiltration. Seasonal variations might be extremely high (-36 per mille for δD and -5.5 per mille for δ18 in 2000/2001). Averaged monthly mixed rainfall samples for October-February 2000/2001 at the two meteostations and some data from springs at the highest altitudes suggest the regression equation for δD(per mille) and the altitude(m): δD = -0.012H(m) - 24,86 (1), where H(m) - the altitude of the rainfall 2H and 18O in groundwater. Almost all points at the 2H versus 18O diagram (except some in the ophiolites) are displaced from the local meteoric water line due to evaporation. Samples taken from the sedimentary rocks seem to be more affected by evaporation than those in ophiolites. Seasonal

  5. 22 years cycle in the planktonic {delta}{sup 18} O of a shallow-water Ionian sea area

    Energy Technology Data Exchange (ETDEWEB)

    Cini Castagnoli, G.; Bonino, G.; Taricco, C. [Turin Univ., Turin (Italy). Dipt. di Fisica Generale; Consiglio Nazionale delle Ricerche, Turin (Italy). Ist. di Cosmogeofisica

    2000-08-01

    The {delta}{sup 18} O profile of Globigerinoides ruber was measured in the GT90/3 Ionian sea core between 1205 and 1898 AD. The high temporal resolution of 3.87 years allowed to determine the presence in the time series of an 11 years component with an amplitude of 0.07%, at significance level of 99% (by Monte Carlo singular spectrum analysis, MC-SSA). The paper focuses attention on 22 years periodicity in the time series and shows the Hale solar cycle, obtained by inverting the odd cycles of the sunspot number series. This result shows that the even and odd Schwabe cycles do not have the same influence on this climatic record.

  6. Investigation on the interactions between soil water, irrigation and transpiration in the soil-plant-atmosphere continuum with 18O

    International Nuclear Information System (INIS)

    Full text: The complex interaction between plant and soil water during the cropping season requires further investigation. How does the plant react in terms of transpiration to water stress during its growth? How is the interaction between the plant, the soil water and irrigation at different levels of water stress? These are the questions to be answered by a pot experiment conducted in a glasshouse at Seibersdorf laboratories involving 18O. Oxygen 18 is a rare (natural abundance of 0.2 %), natural and stable isotope of water and therefore very useful for tracking water pathways from irrigation or precipitation within the soil-plant-atmosphere continuum. One of the noteworthy properties of 18O is the temperature dependency of its fractionation factor between the liquid phase and the vapour during evaporation, while the plant water uptake does not change the isotopic signature of soil water. These two properties can be exploited to investigate not only soil evaporation and plant transpiration but also the irrigation water pathway within the soil-plant-atmosphere continuum. Thirty six large pots (diam. 50 cm) were filled with a 1:1 Seibersdorf soil (diam. 0.5 cm)/quartz sand mixture in a randomised block experiment, consisting of 3 treatments: (i) field capacity + crop, (ii) 60% of field capacity + crop and (iii) 60% of field capacity + bare soil. The crop used for the experiment is corn (Zea Mays). Climatic data and soil humidity will be monitored during the cropping season. Oxygen 18 in irrigation, soil and plant water (sap and dry organic matter) at different stages of plant growth will be analysed. Soil water and plant sap will need to be extracted before isotopic analyses with the mass-spectrometer can be conducted, involving the construction of a cryodistillation line in the laboratory. (author)

  7. The influence of temperature and seawater carbonate saturation state on 13C–18O bond ordering in bivalve mollusks

    Directory of Open Access Journals (Sweden)

    R. A. Eagle

    2013-07-01

    Full Text Available The shells of marine mollusks are widely used archives of past climate and ocean chemistry. Whilst the measurement of mollusk δ18O to develop records of past climate change is a commonly used approach, it has proven challenging to develop reliable independent paleothermometers that can be used to deconvolve the contributions of temperature and fluid composition on molluscan oxygen isotope compositions. Here we investigate the temperature dependence of 13C–18O bond abundance, denoted by the measured parameter Δ47, in shell carbonates of bivalve mollusks and assess its potential to be a useful paleothermometer. We report measurements on cultured specimens spanning a range in water temperatures of 5 to 25 °C, and field collected specimens spanning a range of −1 to 29 °C. In addition we investigate the potential influence of carbonate saturation state on bivalve stable isotope compositions by making measurements on both calcitic and aragonitic specimens that have been cultured in seawater that is either supersaturated or undersaturated with respect to aragonite. We find a robust relationship between Δ47 and growth temperature. We also find that the slope of a linear regression through all the Δ47 data for bivalves plotted against seawater temperature is significantly shallower than previously published inorganic and biogenic carbonate calibration studies produced in our laboratory and go on to discuss the possible sources of this difference. We find that changing seawater saturation state does not have significant effect on the Δ47 of bivalve shell carbonate in two taxa that we examined, and we do not observe significant differences between Δ47-temperature relationships between calcitic and aragonitic taxa.

  8. A STUDY OF THE DYNAMICAL STABILITY OF THE C18O(J = 1-0) CLUMPS IN CEPHEUS OB3 MOLECULAR CLOUD%Cepheus OB3分子云中C18O(J=1-0)团块的稳定性研究

    Institute of Scientific and Technical Information of China (English)

    俞志尧

    2001-01-01

    银河系中的巨分子复合体,例如Cep OB3分子云,在其星际分子的射电谱线成图时表现出成团块的现象.利用它们的物理参数以及维里理论研究了Cep OB3分子云C18O(J=1-0)团块的动力学稳定性.计算结果表明:除L1211的C18O(J=1-0)团块外,其它所有的C18O(J=1-0)团块都存在关系式Pext≤ Pmax和Rmin≤ R.也就是说除L1211的C18O(J=1-0)团块外,其它所有的C18O(J=1-0)团块均是动力学稳定的.由此可信在L1211的C18O(J=1-0)团块中存在恒星形成过程.%The dynamical stability of the C18O(J = 1-0) clumps in the Cep OB3 with the virial theorem using their physical parameters is studied. The results indicate that there are Pext < Pmax and Rmin ≤ R in all of the C18O(J= 1-0) clumps except the L1211 C18O(J = 1-0) clump, i.e. all of the C18O(J = 1-0) clumps except the L1211 C18O(J = 1-0) clump are found to be dynamically stable, and there may be a star forming process in the L1211 C18O(J = 1-0) clump.

  9. 低δ18O岩浆岩的成因%On the origin of low δ18O magmatic rocks

    Institute of Scientific and Technical Information of China (English)

    张少兵; 郑永飞

    2011-01-01

    silicate rocks. Decades of geochemical studies on two classical cases of low δ18O magmas, Yellowstone rhyolites and Iceland basalts, have demonstrated that the mechanism to form the low δ18O magmas is through the partial melting of low δ18O rocks or the assimilation of normal δ18O magmas by low δ18O rocks during magma emplacement In either case, there are preexisting low δ18O rocks prior to the low δ18O magmatism. The low δ18O rocks can be generated by high-T hydrothermal alteration of surface water (seawater or meteoric water). The low δ18O magmatism usually takes place in rifting tectonic zones, with development of caldera collapse and subsequent remelting of low δ18O rocks. The granites at Seychelles in Indian Ocean and Nianzhishan in Northeast China represent two examples of low δ18O granites crystallized from low δ18O magmas. Their formation calls for the involvement of l8O-depleted materials in the magma source. The extent of l8O-depletion in the Dabie-Sulu metamorphic rocks and their extensive occurrences is very remarkable. The most negative δ18O rock-forming minerals were found in granite in the Dabie orogen, but with positive δ18O values for zircons of Neoproterozoic U-Pb ages. It is inferred that the low δ18O granite would have experienced two-stage water-rock interaction at high temperatures. The first leads to the formation of low δ18O magma and thus the crystallization of low δ18O zircons, and the second is characterized by the high-T meteoric-hydrothermal alteration and thus the further decrease of δ18O values for rock-forming minerals. More studies on the low δ18O granites, particularly microscale in-situ oxygen isotope analyses, will be helpful to the understanding of the mechanism of low δ18O magmatism. This can place basic geochemical constraints on the elements and isotopes behavior in the proceses of water-rock interaction.

  10. Comprehensive inter-laboratory calibration of reference materials for δ18O versus VSMOW using various on-line high-temperature conversion techniques

    Science.gov (United States)

    Brand, Willi A.; Coplen, Tyler B.; Aerts-Bijma, Anita T.; Böhlke, J.K.; Gehre, Matthias; Geilmann, Heike; Groning, Manfred; Jansen, Henk G.; Meijer, Harro A. J.; Mroczkowski, Stanley J.; Qi, Haiping; Soergel, Karin; Stuart-Williams, Hilary; Weise, Stephan M.; Werner, Roland A.

    2009-01-01

    Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC)a in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125‰, an artificially enriched reference water (δ18O of +78.91‰) and two barium sulfates (one depleted and one enriched in 18O) were prepared and calibrated relative to VSMOW2b and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study, which yielded: Reference materialδ18O and estimated combined uncertainty c IAEA-602 benzoic acid

  11. Monthly sea surface temperature records reconstructed by δ18O of reef-building coral in the east of Hainan Island,South China Sea

    Institute of Scientific and Technical Information of China (English)

    HE; Xuexian(何学贤); LIU; Dunyi(刘敦一); PENG; Zicheng(彭子成); LIU; Weiguo(刘卫国)

    2002-01-01

    Stable oxygen isotopic compositions of a coral colony of Porites lutea obtained on a core allowed the reconstruction of a 56-a (1943-1998) proxy record of the sea surface temperatures. This coral δ18O data are from the east of Hainan Island water (22°20′N, 110°39′E), South China Sea. The relationship between δ18O in the skeletal aragonite carbonate and the sea surface temperature (SST) is SST = -5.36 δ18OPDB-3.51 (r = 0.73, n = 470), dδ18O/d(SST) = -0.187‰/ ℃; and the thermometer was set at monthly resolution. The 56-a (1943-1998) proxy record of the sea surface temperatures reflected the same change trend in the northern part of South China Sea as the air temperature change trend in China.

  12. Comprehensive inter-laboratory calibration of reference materials for d18O versus VSMOW using various on-line high-temperature conversion techniques

    Science.gov (United States)

    Coplen, Tyler B.; Bohlke, Johnkarl F.; Mroczkowski, Stanley J.; Qi, Haiping; Brand, Willi A.; Aerts-Bijma, Anita T.; Gehre, Matthias; Geilmann, Heike; Groning, Manfred

    2009-01-01

    "Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC) in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125‰, an artificially enriched reference water (d18O of +78.91‰) and two barium sulfates (one depleted and one enriched in 18O) were prepared and calibrated relative to VSMOW2 and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study, which yielded: Reference material d18O and estimated combined uncertainty

  13. An early Pleistocene Mg/Ca-δ18O record from the Gulf of Mexico: Evaluating ice sheet size and pacing in the 41-kyr world

    Science.gov (United States)

    Shakun, Jeremy D.; Raymo, Maureen E.; Lea, David W.

    2016-07-01

    Early Pleistocene glacial cycles in marine δ18O exhibit strong obliquity pacing, but there is a perplexing lack of precession variability despite its important influence on summer insolation intensity - the presumed forcing of ice sheet growth and decay according to the Milankovitch hypothesis. This puzzle has been explained in two ways: Northern Hemisphere ice sheets instead respond to insolation integrated over the summer, which is mostly controlled by obliquity, or anti-phased precession-driven variability in ice volume between the hemispheres cancels out in global δ18O, leaving the in-phase obliquity signal to dominate. We evaluated these ideas by reconstructing Laurentide Ice Sheet (LIS) meltwater discharge to the Gulf of Mexico from 2.55-1.70 Ma using foraminiferal Mg/Ca and δ18O. Our δ18Osw record displays six prominent anomalies, which likely reflect meltwater pulses, and they have several remarkable characteristics: (1) their presence suggests that the LIS expanded into the mid-latitudes numerous times; (2) they tend to occur or extend into interglacials in benthic δ18O; (3) they generally correlate with summer insolation intensity better than integrated insolation forcing; and (4) they are perhaps smaller in amplitude but longer in duration than their late Pleistocene counterparts, suggesting comparable total meltwater fluxes. Overall, these observations suggest that the LIS was large, sensitive to precession, and decoupled from marine δ18O numerous times during the early Pleistocene - observations difficult to reconcile with a straightforward interpretation of the early Pleistocene marine δ18O record as a proxy for Northern Hemisphere ice sheet size driven by obliquity forcing at high latitudes.

  14. Report on the supply and demand of 18O enriched water. Ad hoc committee of the North American Society for the Study of Obesity, 21 January 1999

    International Nuclear Information System (INIS)

    Oxygen-18 is a stable isotope that is used as a tracer for several biomedical applications. The two primary applications are the study of organismal energy expenditure and organ specific utilization of glucose. The former uses 18O along with deuterium to measure carbon dioxide production of free-living animals and humans. Total energy expenditure is calculated from carbon dioxide production using the standard equations of indirect calorimetry. The later uses 18O as a precursor for the production of 18F, a radionuclide that is incorporated into glucose homologues and injected into the circulating blood. When the glucose homologues are taken up by an organ (usually brain), the organ can be imaged using positron emission tomography (PET). Both of these techniques have become major research and, in the case of PET, diagnostic tools during the last decade. This growth in the use of these tools has increased the world-wide demand for 18O in the form of water. In 1998, this demand could not be met by suppliers and significant delivery delays have been encountered by many investigators and clinicians. Some suppliers are quoting delivery delays of a year. These delays have disrupted on-going research and delayed the start of new projects. The shortage has resulted in a price increase of nearly 50% in 18O water. The disruption of 18O supply in 1998 is the second such disruption in the past decade. Commercial suppliers could not provide sufficient product in late 1990 following the forced closure of the US government production facility at Los Alamos Laboratory. Delivery delays lasted throughout 1991. In August of 1998, the council of the North American Association for the Study of Obesity formed an ad hoc committee to gather information regarding the supply and demand for 18O and to investigate potential solutions to the problem

  15. Oxygen isotope ratios (18O/16O) of hemicellulose-derived sugar biomarkers in plants, soils and sediments as paleoclimate proxy I: Insight from a climate chamber experiment

    Science.gov (United States)

    Zech, Michael; Mayr, Christoph; Tuthorn, Mario; Leiber-Sauheitl, Katharina; Glaser, Bruno

    2014-02-01

    The oxygen isotopic composition of cellulose is a valuable proxy in paleoclimate research. However, its application to sedimentary archives is challenging due to extraction and purification of cellulose. Here we present compound-specific δ18O results of hemicellulose-derived sugar biomarkers determined using gas chromatography-pyrolysis-isotope ratio mass spectrometry, which is a method that overcomes the above-mentioned analytical challenges. The biomarkers were extracted from stem material of different plants (Eucalyptus globulus, Vicia faba and Brassica oleracea) grown in climate chamber experiments under different climatic conditions. The δ18O values of arabinose and xylose range from 31.4‰ to 45.9‰ and from 28.7‰ to 40.8‰, respectively, and correlate highly significantly with each other (R = 0.91, p hemicellulose-derived sugar biomarkers, like cellulose, reflect the oxygen isotopic composition of plant source water altered by climatically controlled evapotranspirative 18O enrichment of leaf water. While relative air humidity controls most rigorously the evapotranspirative 18O enrichment, the direct temperature effect is less important. However, temperature can indirectly exert influence via plant physiological reactions, namely by influencing the transpiration rate which affects δ18Oleaf water due to the Péclet effect. In a companion paper (Tuthorn et al., this issue) we demonstrate the applicability of the hemicellulose-derived sugar biomarker δ18O method to soils and provide evidence from a climate transect study confirming that relative air humidity exerts the dominant control on evapotranspirative 18O enrichment of leaf water. Finally, we present a conceptual model for the interpretation of δ18Ohemicellulose records and propose that a combined δ18Ohemicellulose and δ2Hn-alkane biomarker approach is promising for disentangling δ18Oprecipitation variability from evapotranspirative 18O enrichment variability in future paleoclimate studies

  16. Effect of photosynthesis on the abundance of 18O13C16O in atmospheric CO2

    Science.gov (United States)

    Hofmann, Magdalena E. G.; Pons, Thijs L.; Ziegler, Martin; Lourens, Lucas J.; Röckmann, Thomas

    2016-04-01

    The abundance of the isotopologue 18O13C16O (Δ47) in atmospheric air is a promising new tracer for the atmospheric carbon cycle (Eiler and Schauble, 2004; Affek and Eiler, 2006; Affek et al., 2007). The large gross fluxes in CO2 between the atmosphere and biosphere are supposed to play a major role in controlling its abundance. Eiler and Schauble (2004) set up a box model describing the effect of air-leaf interaction on the abundance of 18O13C16O in atmospheric air. The main assumption is that the exchange between CO2 and water within the mesophyll cells will imprint a Δ47 value on the back-diffusing CO2 that reflects the leaf temperature. Additionally, kinetic effects due to CO2 diffusion into and out of the stomata are thought to play a role. We investigated the effect of photosynthesis on the residual CO2 under controlled conditions using a leaf chamber set-up to quantitatively test the model assumptions suggested by Eiler and Schauble (2004). We studied the effect of photosynthesis on the residual CO2 using two C3 and one C4 plant species: (i) sunflower (Helianthus annuus), a C3 species with a high leaf conductance for CO2 diffusion, (ii) ivy (Hedera hibernica), a C3 species with a low conductance, and (iii), maize (Zea mays), a species with the C4 photosynthetic pathway. We also investigated the effect of different light intensities (photosynthetic photon flux density of 200, 700 and 1800 μmol m2s‑1), and thus, photosynthetic rate in sunflower and maize. A leaf was mounted in a cuvette with a transparent window and an adjustable light source. The air inside was thoroughly mixed, making the composition of the outgoing air equal to the air inside. A gas-mixing unit was attached at the entrance of the cuvette that mixed air with a high concentration of scrambled CO2 with a Δ47 value of 0 to 0.1‰ with CO2 free air to set the CO2 concentration of ingoing air at 500 ppm. The flow rate through the cuvette was adjusted to the photosynthetic activity of the

  17. Quantitation of peptides and proteins by matrix-assisted laser desorption/ionization mass spectrometry using (18)O-labeled internal standards

    DEFF Research Database (Denmark)

    Mirgorodskaya, O A; Kozmin, Y P; Titov, M I;

    2000-01-01

    A method for quantitating proteins and peptides in the low picomole and sub-picomole range has been developed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with internal (18)O-labeled standards. A simple procedure is proposed to produce such internal standards...... for the tested sample by enzymatic hydrolysis of the same sample (with known concentration) in (18)O-water. A mathematical algorithm was developed which uses the isotopic patterns of the substance, the internal standard, and the substance/internal standard mixture for accurate quantitation of the substance...

  18. Syn-volcanic cannibalisation of juvenile felsic crust: Superimposed giant 18O-depleted rhyolite systems in the hot and thinned crust of Mesoproterozoic central Australia

    Science.gov (United States)

    Smithies, R. H.; Kirkland, C. L.; Cliff, J. B.; Howard, H. M.; Quentin de Gromard, R.

    2015-08-01

    Eruptions of voluminous 18O-depleted rhyolite provide the best evidence that the extreme conditions required to produce and accumulate huge volumes of felsic magma can occur in the upper 10 km of the crust. Mesoproterozoic bimodal volcanic sequences from the Talbot Sub-basin in central Australia contain possibly the world's most voluminous accumulation of 18O-depleted rhyolite. This volcanic system differs from the better known, but geochemically similar, Miocene Snake River Plain - Yellowstone Plateau of North America. Both systems witnessed 'super' sized eruptions from shallow crustal chambers, and produced 18O-depleted rhyolite. The Talbot system, however, accumulated over a much longer period (>30 Ma), at a single depositional centre, and from a magma with mantle-like isotopic compositions that contrast strongly with the isotopically evolved basement and country-rock compositions. Nevertheless, although the Talbot rhyolites are exclusively 18O-depleted, the unavoidable inference of an 18O-undepleted precursor requires high-temperature rejuvenation of crust in an upper-crustal chamber, and in this respect the evolution of the Talbot rhyolites and 18O-depleted rhyolites of the Snake River Plain - Yellowstone Plateau is very similar. However, instead of older crustal material, the primary upper-crustal source recycled into Talbot rhyolites was comagmatic (or nearly so) felsic rock itself derived from a contemporaneous juvenile basement hot-zone. Whereas giant low δ18O volcanic systems show that voluminous melting of upper crust can occur, our studies indicate that felsic magmas generated at lower crustal depths can also contribute significantly to the thermal and material budget of these systems. The requirement that very high-temperatures be achieved and sustained in the upper crust means that voluminous low δ18O magmatism is rare, primarily restricted to bimodal tholeiitic, high-K rhyolite (A-type) magmatic associations in highly attenuated lithosphere. In the

  19. Millennial δ18O oscillations from a replicated Holocene speleothem record from Iberian Peninsula and hemispherical teleconecctions affecting the water cycle

    Science.gov (United States)

    Domínguez-Villar, David; Wang, Xianfeng; Krklec, Kristina; Cheng, Hai; Edwards, R. Lawrence

    2016-04-01

    We present a speleothem δ18O record from Kaite Cave in northern Iberian Peninsula covering the last 9.7 ka BP. The record is constructed from four different stalagmites that replicate each other. The age model is based on 63 U-Th dates and over 4500 laminae providing a robust time frame for the record. The δ18O record has characteristic millennial oscillations through the Holocene with periodicity around 2 ka during the Late Holocene and around 1 ka during the Early Holocene. Causes of the millennial δ18O variability are not dominated by the amount of rainfall or atmospheric temperature and other controls of the water cycle are more relevant. The aquifer at this site filters any seasonal bias and speleothems records the inter-annual δ18O variability in precipitation. On the other hand, moisture source analysis at this site shows that significant amount of precipitation is from recycled moisture (continental origin). A variable proportion of this parameter is capable to impact significantly past values of δ18O in precipitation. Thus, we interpret the millennial oscillations of the δ18O record as changes in the hydrological cycle resulting from variable percentages of the recycled precipitation over the Iberian Peninsula. We found that variable amount of recycled precipitation in Iberian Peninsula is related to the location of the Iceland Low pressure cell, although does not correlate with NAO index. Correlation of Kaite δ18O record during the Holocene with other representative records suggests that millennial oscillations are caused by variability of the Gulf Stream/North Atlantic Current that affects atmospheric pressure fields in the North Atlantic. Further correlation of Kaite δ18O record along the world supports that the recorded millennial oscillations of the water cycle are related to persistent variability on the tropical North Atlantic. Only during periods of major sea-ice variability in high-latitudes of the North Atlantic, the later region replaces

  20. Cave Monitoring to Determine the Controls on δ18O From a Modern Speleothem Record in Semi-arid SE Australia.

    Science.gov (United States)

    Markowska, M.; Baker, A.; Andersen, M. S.; Jex, C.; Cuthbert, M. O.; Rau, G. C.; Graham, P. W.; Rutlidge, H.; Marjo, C.; Treble, P. C.

    2015-12-01

    Cave monitoring provides a crucial link between hydrological and climate processes and how they may in turn effect speleothem δ18O calcite composition. This is particularly important in arid environments where potential evapotranspiration (PET) exceeds precipitation (P) and may dominate the δ18O signature. In this study we investigate climate-karst-cave interactions driving the δ18O variability in modern drip water samples from Cathedral Cave in semi-arid SE Australia and use this information to interpret a modern sub-annually resolved speleothem record. Over a two-year monitoring campaign we established that mean composition of δ18O in modern drip waters was enriched by up to 2.9‰, relative to the weighted mean annual rainfall. Furthermore, fluctuations in δ18O over time were controlled by two processes (1) evaporation in the unsaturated zone, resulting in heavier values, and (2) recharge during infiltration events, resulting in isotopically lighter values. Large soil moisture deficits in the soil zone must therefore be surpassed to initiate infiltration, resulting in relatively infrequent (0-3 per year) infiltration events. A series of infiltration experiments were conducted to elucidate water flow delivery mechanisms and water residence times. We found that the hydrological pathways and resulting mixing processes that occurred in the unsaturated zone determined the isotopic variability in the drip water δ18O between individual drip sites, and that potential storage in the unsaturated zone is generally greater than 6 months. We establish that the δ18O record in speleothems from this cave do not exclusively record rainfall composition or amount but are overlaid with an evaporative signal that is strongly affected by the time since the last infiltration event, local hydrogeology, cave climate and disequilibrium during calcite deposition. This hypothesis was tested by reconstructing the δ18O proxy record in a speleothem growing for ~50 years in the

  1. High latitude meteoric δ18O compositions: Paleosol siderite in the Middle Cretaceous Nanushuk Formation, North Slope, Alaska

    Science.gov (United States)

    Ufnar, David F.; Ludvigson, Greg A.; Gonzalez, Luis A.; Brenner, Richard L.; Witzke, Brian J.

    2004-01-01

    Siderite-bearing pedogenic horizons of the Nanushuk Formation of the North Slope, Alaska, provide a critical high paleolatitude oxygen isotopic proxy record of paleoprecipitation, supplying important empirical data needed for paleoclimatic reconstructions and models of "greenhouse-world" precipitation rates. Siderite ??18O values were determined from four paleosol horizons in the National Petroleum Reserve Alaska (NPR-A) Grandstand # 1 Core, and the values range between -17.6??? and -14.3??? Peedee belemnite (PDB) with standard deviations generally less than 0.6??? within individual horizons. The ??13C values are much more variable, ranging from -4.6??? to +10.8??? PDB. A covariant ??18O versus ??13C trend in one horizon probably resulted from mixing between modified marine and meteoric phreatic fluids during siderite precipitation. Groundwater values calculated from siderite oxygen isotopic values and paleobotanical temperature estimates range from -23.0??? to -19.5??? standard mean ocean water (SMOW). Minor element analyses show that the siderites are impure, having enrichments in Ca, Mg, Mn, and Sr. Minor element substitutions and Mg/Fe and Mg/ (Ca + Mg) ratios also suggest the influence of marine fluids upon siderite precipitation. The pedogenic horizons are characterized by gleyed colors, rare root traces, abundant siderite, abundant organic matter, rare clay and silty clay coatings and infillings, some preservation of primary sedimentary stratification, and a lack of ferruginous oxides and mottles. The pedogenic features suggest that these were poorly drained, reducing, hydromorphic soils that developed in coal-bearing delta plain facies and are similar to modern Inceptisols. Model-derived estimates of precipitation rates for the Late Albian of the North Slope, Alaska (485-626 mm/yr), are consistent with precipitation rates necessary to maintain modern peat-forming environments. This information reinforces the mutual consistency between empirical

  2. Down Core Oxygen Isotopic Measurements Of Diatom δ18O From The Guaymas Basin, Gulf Of California

    Science.gov (United States)

    Menicucci, A. J.; Spero, H. J.; Thunell, R.

    2015-12-01

    The Guaymas Basin (GB), Gulf of California (27º53'N, 111º40'W ), is an evaporative basin, with sea surface temperatures (SST) varying between ~30oC (summer) and ~15oC (winter). Productivity is controlled mostly by seasonal upwelling starting in fall (early November) and extending into spring. We are currently analyzing δ18Odiatom from a boxcore (BC-43) using microfluorination (Menicucci, et al. 2013). This boxcore was previously analyzed for UK '37 alkenones and 210Pb activity (Goni, et al. 2001). Residual BC-43 material was sampled at ~2cm intervals. Samples were cleaned to isolate diatoms from other sediments, then equilibrated in water with δ18Owater = +85‰ for 70 hours at 21oC prior to vacuum dehydroxylation and microfluorination. The latter equilibration was done to account for fractionation between covalently bound O and OH- groups during vacuum dehydroxylation, preserving the original δ18Odiatom value. We present δ18Odiatom data from BC-43 samples covering 27cm, equivalent to >225 years of sediment accumulation. δ18O data are converted to temperature (T) based on an existing calibration (Leclerc and Labeyrie 1987). Our data suggest δ18Odiatom values record a T range of 22-18oC, corresponding to the mixed layer depth and the chlorophyll maximum during the fall bloom. These T values are offset from SST data by a mean of 5oC for the same sample intervals. However, δ18Odiatom values from the most recent samples suggest a ~2oC increase in diatom T relative to SST during the last 35 years. This subsurface warming may be due to decreased fall upwelling, increased mixed layer and chlorophyll maximum depths, and/or the timing of the peak diatom bloom. Such correlations are being investigated and the latest results will be presented. Goni, M. A., et al. (2001). Oceanographic considerations for the application of the alkenone-based paleotemperature U-37(K ') index in the Gulf of California. Geochimica Et Cosmochimica Acta 65: 545-557. Leclerc, A. J. and L

  3. Linking water and carbon fluxes in a Mediterranean oak woodland using a combined flux and ?18O partitioning approach

    Science.gov (United States)

    Dubbert, M.; Piayda, A.; Costa e Silva, F.; Correia, A.; Pereira, J. S.; Cuntz, M.; Werner, C.

    2013-12-01

    Water is one of the key factors driving ecosystem productivity, especially in water-limited ecosystems, where global climate change is expected to intensify drought and alter precipitation patterns. One such ecosystem is the ';Montado', where two vegetation layers respond differently to drought: oak trees avoid drought due to their access to deeper soil layers and ground water while herbaceous plants, surviving the summer in the form of seeds. We aimed at 1) quantifying the impact of the understory herbaceous vegetation on ecosystem carbon and water fluxes throughout the year, 2) determining the driving environmental factors for evapotranspiration (ET) and net ecosystem exchange (NEE) and 3) disentangling how ET components of the ecosystem relate to carbon dioxide exchange. We present one year data set comparing modeled and measured stable oxygen isotope signatures (δ18O) of soil evaporation, confirming that the Craig and Gordon equation leads to good agreement with measured δ18O of evaporation (Dubbert et al. 2013). Partitioning ecosystem ET and NEE into its three sources revealed a strong contribution of soil evaporation (E) and herbaceous transpiration (T) to ecosystem ET during spring and fall. In contrast, soil respiration (R) and herbaceous net carbon gain contributed to a lesser amount to ecosystem NEE during spring and fall, leading to consistently smaller water use efficiencies (WUE) of the herbaceous understory compared to the cork-oaks. Here, we demonstrate that the ability to assess ET, NEE and WUE independent of soil evaporation dynamics enables the understanding of the mechanisms of the coupling between water and carbon fluxes and their responses to drought. Dubbert, M., Cuntz, M., Piayda, A., Maguas, C., Werner, C., 2013: Partitioning evapotranspiration - Testing the Craig and Gordon model with field measurements of oxygen isotope ratios of evaporative fluxes. J Hydrol. a) Oxygen isotope signatures of soil evaporation on bare soil plots calculated

  4. The effect of skeletal mass accumulation in Porites on coral Sr/Ca and δ18O paleothermometry

    Science.gov (United States)

    Gagan, Michael K.; Dunbar, Gavin B.; Suzuki, Atsushi

    2012-03-01

    Paleotemperature estimates based on coral Sr/Ca have not been widely accepted because the reconstructed glacial-Holocene shift in tropical sea-surface temperature (˜4-6°C) is larger than that indicated by foraminiferal Mg/Ca (˜2-4°C). We show that corals over-estimate changes in sea-surface temperature (SST) because their records are attenuated during skeletogenesis within the living tissue layer. To quantify this process, we microprofiled skeletal mass accumulation within the tissue layer of Porites from Australasian coral reefs and laboratory culturing experiments. The results show that the sensitivity of the Sr/Ca and δ18O thermometers in Porites will be suppressed, variable, and dependent on the relationship between skeletal growth rate and mass accumulation within the tissue layer. Our findings help explain why δ18O-SST sensitivities for Porites range from -0.08‰/°C to -0.22‰/°C and are always less than the value of -0.23‰/°C established for biogenic aragonite. Based on this observation, we recalibrated the coral Sr/Ca thermometer to determine a revised sensitivity of -0.084 mmol/mol/°C. After rescaling, most of the published Sr/Ca-SST estimates for the Indo-Pacific region for the last ˜14,000 years (-7°C to +2°C relative to modern) fall within the 95% confidence envelope of the foraminiferal Mg/Ca-SST records. We conclude that two types of calibration scales are required for coral paleothermometry; an attenuated Porites-specific thermometer sensitivity for studies of seasonal to interannual change in SST and, importantly, the rescaled -0.084 mmol/mol/°C Sr/Ca sensitivity for studies of 20th-century trends and millennial-scale changes in mean SST. The calibration-scaling concept will apply to the development of transfer functions for all geochemical tracers in corals.

  5. Diagnosing Atmospheric Influences on the Interannual 18O/16O Variations in Western U.S. Precipitation

    Directory of Open Access Journals (Sweden)

    Kei Yoshimura

    2013-07-01

    Full Text Available Many climate proxies in geological archives are dependent on the isotopic content of precipitation (δ18Op, which over sub-annual timescales has been linked to temperature, condensation height, atmospheric circulation, and post-condensation exchanges in the western U.S. However, many proxies do not resolve temporal changes finer than interannual-scales. This study explores causes of the interannual variations in δ18Op within the western U.S. Simulations with the Isotope-incorporated Global Spectral Model (IsoGSM revealed an amplifying influence of post-condensation exchanges (i.e., raindrop evaporation and vapor equilibration on interannual δ18Op variations throughout the western U.S. Mid-latitude and subtropical vapor tagging simulations showed that the influence of moisture advection on δ18Op was relatively strong in the Pacific Northwest, but weak over the rest of the western U.S. The vapor tags correlated well with interannual variations in the 18O/16O composition of vapor, an indication that isotopes in vapor trace atmospheric circulation. However, vertical-tagging simulations revealed a strong influence of condensation height on δ18Op in California. In the interior of the western U.S., a strong temperature effect was found only after annual mean temperatures were weighted by monthly precipitation totals. These multiple influences on δ18Op complicate interpretations of western U.S. climate proxies that are derived from isotopes in precipitation.

  6. Model reconstruction of nitrate pollution of riverbank filtration using 15N and 18O data, Karany, Czech Republic

    International Nuclear Information System (INIS)

    Stable isotopes of O (δ18O) in water and N (δ15N) in NO3- have been used as natural indigenous groundwater tracers for sources of water and of NO3- at two riverbank filtration (RBF) water supply systems. Both RBF systems (Skorkov and Sojovice) have wells in unconsolidated Quaternary sediments close to the Jizera River (Czech Republic) that have been affected by increasing NO3- concentrations. The area is underlain by Turonian sandstones and marls that form a deeper bedrock aquifer. Sources of NO3- are local sewerage systems and landfills (point sources) and seasonal application of manure and inorganic fertilizers (diffuse sources). At RBF Skorkov recharge to wells can be modelled using a two-component model with 60% river water contribution and 40% of very shallow groundwater with an average residence time of one month. During periods of abundant precipitation, groundwater originates entirely from the unsaturated zone of the Quaternary aquifer; extensive pumping for over 40a has created new, bypassing flow paths that preferentially drain the contaminated unsaturated zone. During dry periods, wells are recharged by longer residence time groundwater from the Quaternary aquifer. At RBF Sojovice there is an additional recharge component of groundwater from the Turonian aquifer, which is sandier at this locality; this contains denitrified NO3- with highly positive δ15N values

  7. Palaeotemperature reconstruction during the Last Glacial from δ18O of earthworm calcite granules from Nussloch loess sequence, Germany

    Science.gov (United States)

    Prud'homme, Charlotte; Lécuyer, Christophe; Antoine, Pierre; Moine, Olivier; Hatté, Christine; Fourel, François; Martineau, François; Rousseau, Denis-Didier

    2016-05-01

    The Nussloch loess-palaeosol sequence (Rhine Valley, Germany) is considered to be one of the most complete records of the last glacial period in Western Europe due to its very high sedimentation rate and its good chronological control. This sequence is therefore a good framework in which to develop new proxies for palaeoenvironmental reconstructions. In this study, we explore, for the first time, the potential of earthworm calcite granules as a new bio-indicator and climatic proxy of absolute air and soil temperature in the context of Last Glacial loess. These granules are composed of rhomboedric calcite crystals, organized in a radial crystalline structure. As these granules are individually generated by earthworms at a relative fast rate, they are expected to record intra-annual variations in the available sources of oxygen: percolating waters of meteoric origin. We extracted thirty earthworm calcite granules from 11 of 5 cm layers thick from tundra gley and brown soil horizons previously, dated at 45 to 23 ka. Oxygen isotope ratios were measured on each individual granule. The δ18O of calcite granules and interlinked transfer functions between water cycle, air and soil temperatures allowed us to estimate air temperatures ranging from 10 to 12 ± 4°C, which most likely reflect the warm periods of the year when earthworms were the most active.

  8. A coupled D/18O approach to reconstruct the paleohumidity during the Younger Dryas in the Eifel, Germany

    Science.gov (United States)

    Wüthrich, Lorenz; Hepp, Johannes; Bromm, Tobias; Kathrin Schäfer, Imke; Zech, Jana; Sirocko, Frank; Zech, Michael; Zech, Roland

    2016-04-01

    Leaf waxes, such as long-chain n-alkanes and n-alkanoic acids, and their D/H isotopic composition, are increasingly used in lake, marine and eolian sediments to reconstruct past changes in vegetation, as well as the isotopic composition of precipitation. However, evaporative enrichment of leaf water might compromise such reconstructions, and it remains difficult to quantitatively reconstruct past climate changes. For the present study, we have analyzed samples from the Gemündener Maar, a lake situated in the western Eifel, Germany, for their isotopic composition of n-alkanes (D) and sugars (18O). Combination of both isotopes allows calculating not only the isotopic composition of paleo-precipitation, but also relative humidity (rh), based on reconstructed d-excess of leaf water. Our results suggest that the Younger Dryas was not particularly dry compared to the Alleröd. The onset of the Holocene, on the other hand, seems to have been very dry, except for one humid spell. Only with the transition Preboreal/Boreal, rh increased again.

  9. The JCMT Legacy Survey of the Gould Belt: mapping 13CO and C18O in Orion A

    CERN Document Server

    Buckle, J V; Di Francesco, J; Graves, S F; Nutter, D; Richer, J S; Roberts, J F; Ward-Thompson, D; White, G J; Brunt, C; Butner, H M; Cavanagh, B; Chrysostomou, A; Curtis, E I; Duarte-Cabral, A; Etxaluze, M; Fich, M; Friberg, P; Friesen, R; Fuller, G A; Greaves, J S; Hatchell, J; Hogerheijde, M R; Johnstone, D; Matthews, B; Matthews, H; Rawlings, J M C; Sadavoy, S; Simpson, R J; Tothill, N F H; Tsamis, Y G; Viti, S; Wouterloot, J G A; Yates, J

    2012-01-01

    The Gould Belt Legacy Survey will map star-forming regions within 500 pc, using HARP (Heterodyne Array Receiver Programme), SCUBA-2 (Submillimetre Common-User Bolometer Array 2) and POL-2 (Polarimeter 2) on the James Clerk Maxwell Telescope (JCMT). This paper describes HARP observations of the J = 3-2 transitions of 13CO and C18O towards Orion A. The 1500-resolution observations cover 5 pc of the Orion filament, including OMC1 (inc. BN-KL and Orion Bar), OMC 2/3 and OMC 4, and allow a comparative study of the molecular gas properties throughout the star-forming cloud. The filament shows a velocity gradient of ~1 km/s /pc between OMC 1, 2 and 3, and high velocity emission is detected in both isotopologues. The Orion Nebula and Bar have the largest masses and line widths, and dominate the mass and energetics of the high velocity material. Compact, spatially resolved emission from CH3CN, 13CH3OH, SO, HCOOCH3, C2H5OH, CH3CHO and CH3OCHO is detected towards the Orion Hot Core. The cloud is warm, with a median exci...

  10. Water vapour {sup 18}O/{sup 16}O isotope ratio in surface air in New England, USA

    Energy Technology Data Exchange (ETDEWEB)

    Xuhui Lee [Yale Univ., New Haven, CT (United States). School of Forestry and Environmental Studies; Smith, Ronald; Williams, John [Yale Univ., New Haven, CT (United States). Dept. of Geology and Geophysics

    2006-09-15

    In this paper, we report the results of the analysis of two high-resolution time-series of water vapour {sup 18}O/{sup 16}O ratio {delta}{sub v} in surface air observed in Connecticut, USA. On an annual time-scale, {delta}{sub v} is a linear function of ln w, where w is water vapour mixing ratio, and is approximated by a Rayleigh distillation model with partial (80%) rainout. On time scales a few days, {delta}{sub v} shows considerable variations, often exceeding 20 per mil, and is higher in the wetting phase than in the drying phase of a weather cycle. In precipitation events, the vapour in the surface layer is in general brought to state of equilibrium with falling raindrops but not with snowflakes. On a diurnal time-scale, a peak-to-peak variation of 1-2 per mil is observed at a coastal site. At an interior site, evidence of a diurnal pattern is present only on days of low humidity. Our results suggest that the intercept parameter of the Keeling plot is an ambiguous quantity and should not be interpreted as being equivalent to the isotopic signature of evapotranspiration.

  11. Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O + 232Th reaction

    Science.gov (United States)

    Léguillon, R.; Nishio, K.; Hirose, K.; Makii, H.; Nishinaka, I.; Orlandi, R.; Tsukada, K.; Smallcombe, J.; Chiba, S.; Aritomo, Y.; Ohtsuki, T.; Tatsuzawa, R.; Takaki, N.; Tamura, N.; Goto, S.; Tsekhanovich, I.; Petrache, C. M.; Andreyev, A. N.

    2016-10-01

    It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O + 232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation-dissipation model.

  12. Effect of N/Z in pre-scission neutron multiplicity for 16,18O+198Pt systems

    International Nuclear Information System (INIS)

    This paper reports the summary of the experimental results of pre-scission neutron multiplicities from four compound nuclei, namely 210,212,214,216Rn, and statistical model analysis of the corresponding data. The compound nuclei 210,212,214,216Rn having N/Z values as 1.441, 1.465, 1.488, 1.511 respectively are populated through the 16,18O+194,198Pt reactions at excitation energies of 50, 61, 71.7 and 79 MeV. The measured neutron multiplicities are further analyzed with the statistical model of nuclear decay where fission hindrance due to nuclear dissipation is considered. The N/Z dependence of the dissipation strength at lowest excitation energy of the compound nuclei suggests shell closure effects. However, such effects are not observed at higher excitations where the variation of the dissipation strength with N/Z does not show any specific trend. The variation of N/Z in fission time scale is also shown. (authors)

  13. Evaluation of the effects of microscale chemical and isotopic heterogeneity of coral skeleton on conventional Sr/Ca and 18O paleothermometers

    Indian Academy of Sciences (India)

    Takehiro Mitsuguchi

    2013-10-01

    Recent studies using secondary ion mass spectrometry revealed microscale heterogeneity of Sr/Ca and 18O in shallow-water coral skeletons, i.e., Sr/Ca and 18O differ significantly between two basic microfeatures of the skeleton: the center of calcification (COC) and surrounding fibrous skeleton (SFS). The COC, in contrast with the SFS, consists of highly irregular crystals intermingled with significant amount of organic matter; therefore, analyzing the SFS only would probably be favourable for paleotemperature reconstruction. Conventional Sr/Ca and 18O paleothermometers are, however, based on the analysis of the mixture of the COC and SFS, and thus may be significantly affected by the above-mentioned heterogeneity. In this study, I have evaluated the heterogeneity-induced effects on the conventional paleothermometers of Porites skeletons using published Sr/Ca, 18O and volume-fraction data of the COC and SFS and published observations of seasonal variability of bulk skeletal density. Results indicate that the effects may yield significant or serious errors in paleotemperature reconstruction.

  14. The effect of acid rain and altitude on concentration, δ34S, and δ18O of sulfate in the water from Sudety Mountains, Poland

    Science.gov (United States)

    Szynkiewicz, Anna; Modelska, Magdalena; Jedrysek, Mariusz Orion; Mastalerz, Maria

    2008-01-01

    The analyses of sulfate content, δ34S and δ18O of dissolved sulfate, and δ18O of water were carried out in a 14 km2 crystalline massif located in the Sudety Mountains (SW Poland) to 1) assess the amount of the sulfate delivered to the surface and groundwater systems by modern atmospheric precipitation, 2) determine the effect of altitude on these parameters, and 3) investigate their seasonal variations. In April and November of 2002, August 2003, and March and September of 2005, samples of water were collected from springs and streams of the massif. During these seasons, sulfate contents and δ18O(SO42−) values varied from 5.80 to 18.00 mg/l and from 3.96 to 8.23‰, respectively, showing distinctively higher values ofδ18O(SO42−) in wet seasons. The δ34S(SO42−) values had a relatively narrow range from 4.09 to 5.28‰ and were similar to those reported for organic matter in soil and the canopy throughfall in the Sudety Mountains.

  15. Punta Pitt Stable Isotope and Ion Data (delta 18O, delta 13C, Cd/Ca, Mn/Ca) for 1936 to 1982.5

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File contains data presented by Shen et al. (1992a). Table includes d18O, d13C, Cd/Ca, Mn/Ca, and Ba/Ca data from a 2m coral head and, for comparison, SST records...

  16. Past 100 Ky surface salinity-gradient response in the eastern Arabian Sea to the summer monsoon variation recorded by delta super(18)O of G. sacculifer

    Digital Repository Service at National Institute of Oceanography (India)

    Chodankar, A.R.; Banakar, V.K.; Oba, T.

    difference of 1 psu and serves as a calibration for past variations. The residual delta sup(18) O sub(G. sacculifer) contrast varies between approx. 0.2 ppt at approx. 75 ky B.P. (i.e., late-Marine Isotope Stage 5) and approx. 0.7 ppt at approx. 20 ky B.P. (i.e...

  17. Nucleosynthesis in AGB stars traced by isotopic ratios. I - Determining the stellar initial mass by means of the $^{17}$O/$^{18}$O ratio

    CERN Document Server

    De Nutte, R; Olofsson, H; Lombaert, R; de Koter, A; Karakas, A; Milam, S; Ramstedt, S; Stancliffe, R J; Homan, W; Van de Sande, M

    2016-01-01

    The aim of this paper is to investigate the $^{17}$O/$^{18}$O ratio for a sample of AGB stars, containing M-, S- and C-type stars. These ratios are evaluated in relation to fundamental stellar evolution parameters: the stellar initial mass and pulsation period. This study is the first to explore these oxygen ratios for a sample covering the three spectral types. Circumstellar $^{13}$C$^{16}$O, $^{12}$C$^{17}$O and $^{12}$C$^{18}$O line observations were obtained for a sample of nine stars with various single-dish long-wavelength facilities. These data have been fully reduced and analyzed. The line intensity ratios obtained from these observations are then related directly to the surface $^{17}$O/$^{18}$O abundance ratio. Stellar evolution models predict the $^{17}$O/$^{18}$O ratio to be a sensitive function of initial mass and to remain constant throughout the entire TP-AGB phase for stars less massive than 5 M$_{\\odot}$. This allows the measured ratio to function as an effective method of determining the ini...

  18. Identifying residence times and streamflow generation processes using δ18O and δ2H in meso-scale catchments in the Abay/Upper Blue Nile, Ethiopia

    NARCIS (Netherlands)

    Teklaeb, S.; Wenninger, J.W.; Uhlenbrook, S.

    2013-01-01

    Measurements of the stable isotopes oxygen-18 (18O) and deuterium (2H) were carried out in two meso-scale catchments, Chemoga (358 km2) and Jedeb (296 km2) south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin. Stabl

  19. Variations in air temperature during the last 100 years revealed by δ18 O in the Malan ice core from the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    WANG Ninglian; YAO Tandong; PU Jianchen; ZHANG Yongliang; SUN Weizhen; WANG Youqing

    2003-01-01

    By comprehensive analyses, it was found that the variations in δ18O recorded in Malan ice core from the Kekexili Region on the Tibetan Plateau could represent the changes in air temperature during the summer half year (from May to October) over the Kekexili Region and the northern margin of the Tibetan Plateau. The general increase trend in δ18O in this ice core during the past century indicated climate warming, and it was estimated that air temperature during the summer half-year rose about 1.2℃over there then. However, this ice core record documented that the study area has been cooling while most of the world has been dramatically warming since the late 1970s. A teleconnection was found between the variations in δ18O in the Malan ice core and the North Atlantic Oscillation. Moreover,the variations in δ18O in this ice core were similar to that in the summer half-year air temperature over the southern Tibetan Plateau on the centurial time scale, but opposite on the multidecadal time scale.

  20. Two new inorganic-organic hybrid materials based on inorganic cluster, [X2Mo18O62]6− (X=P, As)

    Indian Academy of Sciences (India)

    Fatma Hmida; Meriem Ayed; Brahim Ayed; Amor Haddad

    2015-09-01

    Two new inorganic-organic hybrid materials based on heteropolyoxometalates, (C4H10N)6 (P2 Mo18O62).4H2O I, and (C4H10N)6 (As2Mo18O62).4H2O II, where C4H10N is protonated pyrrolidine have been synthesized and structurally characterized by physic-chemical methods. Single-crystal X-ray diffraction method, infrared, ultraviolet spectroscopy, Thermogravimetricanalysis andcyclic voltammetry measurements of the title hybrid materials indicate that there are hydrogen bond interaction between O atoms of the hetero-polyoxometalates and water molecules as well as the N and O atoms of the organic compound. The molecular structures of synthesized hybrid materials contain discrete entities of pyrrolidinumion and water molecules surround every [X2Mo18O62]6− anion over the extended crystalline network that the [X2Mo18O62]6− anion retains its ``Dawson structure". Crystal data: I monoclinic, space group P21/a, a = 13,453(1) Å, b = 24,046 (1) Å, c = 24,119(1) = 97, 99(1)°, V = 7726,30(5) Å3 and Z = 4; II monoclinic, space group P21/a, a = 13.4900(1) Å, 24.0900(1) Å, 24.2740(1) Å, = 98.320(1)°, V = 7805.40(7) Å3 and Z = 4.

  1. Simultaneous Determination of the 2H/1H, 17O/16O, and 18O/16O Isotope Abundance Ratios in Water by Means of Laser Spectrometry

    NARCIS (Netherlands)

    Kerstel, E.R.Th.; Trigt, R. van; Dam, N.J.; Reuss, J.; Meijer, H.A.J.

    1999-01-01

    We demonstrate the first successful application of infrared laser spectrometry to the accurate, simultaneous determination of the relative H-2/H-1, O-17/O-16, and O-18/O-16 isotope abundance ratios in water. The method uses a narrow Line width color center laser to record the direct absorption spect

  2. Quasiclassical trajectory studies of 18O(3P) + NO2 isotope exchange and reaction to O2 + NO on D0 and D1 potentials

    Science.gov (United States)

    Fu, Bina; Zhang, Dong H.; Bowman, Joel M.

    2013-07-01

    We report quasiclassical trajectory calculations for the bimolecular reaction 18O(3P) + NO2 on the recent potential energy surfaces of the ground (D0) and first excited (D1) states of NO3 [B. Fu, J. M. Bowman, H. Xiao, S. Maeda, and K. Morokuma, J. Chem. Theory. Comput. 9, 893 (2013)], 10.1021/ct3009792. The branching ratio of isotope exchange versus O2 + NO formation, as well as the product angular distributions and energy and rovibrational state distributions are presented. The calculations are done at the collision energy of relevance to recent crossed beam experiments [K. A. Mar, A. L. Van Wyngarden, C.-W. Liang, Y. T. Lee, J. J. Lin, and K. A. Boering, J. Chem. Phys. 137, 044302 (2012)], 10.1063/1.4736567. Very good agreement is achieved between the current calculations and these experiments for the branching ratio and final translational energy and angular distributions of isotope exchange products 16O(3P) + NO2 and O2 + NO formation products. The reactant 18O atom results in 18O16O but not N18O for the O2 + NO formation product channel, consistent with the experiment. In addition, the detailed vibrational and rotational state information of diatomic molecules calculated currently for the 34O2 + NO formation channel on D0 and D1 states are in qualitative agreement with the previous experimental and theoretical results of the photodissociation of NO3 and are consistent with older thermal bimolecular kinetics measurements.

  3. The distribution of radioactive ( 3H, 14C) and stable ( 2H, 18O) isotopes in precipitation, surface and groundwaters of NW Yugoslavia

    Science.gov (United States)

    Horvatinčić, Nada; Krajcar-Bronić, Ines; Pezdič, Jože; Srdoč, Dušan; Obelić, Bogomil

    1986-11-01

    The isotopic measurements ( 2H, 3H, 18O) of precipitiation in Zagreb (since 1976) and Ljubljana (since 1981) in NW Yugoslavia show seasonal variations typical of the Northern hemisphere. Continuous measurements of tritium concentration in the Sava River ca 10 km upstream from Zagreb have been performed since 1976. Data show a smooth line without periodical changes, but a steady decrease is obvious. The sampling place is situated ca 30 km downstream from the Kr\\vsko Nuclear Power Plant. No change in tritium concentration due to the operation of the power plant has been observed. A comprehensive program of monitoring of the 14C activity in air CO 2 as well as in vegetables, cereals and tree-rings in the surroundings of the Nuclear Power Plant Kr\\vsko has been carried out since 1984. The measurement of 2H and 18O in karst springs of the Korana River catchmet area (Plitvice National Park) gave a meteoric water line equal to δ2H = 7.9 δ18O + 8.5, which is typical of the NW part of Yugoslavia. A fairly constant concentration of 2H and 18O in spring water indicates a thorough mixing of water in the karst aquifers. The mean residence time (MRT) of karst water was determined by measuring monthly tritium activity of spring water. The MRT is very short, ranging between 1 and 4 years on average.

  4. Can tree-ring isotopes (δ18O and δ13C) improve our understanding of hydroclimate variability in the Columbia River Basin?

    Science.gov (United States)

    Csank, A. Z.; Wise, E.; McAfee, S. A.

    2015-12-01

    The trajectory of incoming storms from the Pacific Ocean has a strong impact on hydroclimate in the Pacific Northwest. Shifts between zonal and meridional flow are a key influence on drought and pluvial regimes in both the PNW and the western United States as a whole. Circulation-dependent variability in the isotopic composition of precipitation can be recorded and potentially reconstructed using δ18O records derived from tree-rings. Here we present isotopic records of δ18O and δ13C from ponderosa pine (Pinus ponderosa) for the period 1950-2013 from six sites located in the lee of the Cascades in eastern Washington. Because of the orientation of the Cascades, zonal flow will result in an intensified rain shadow whereas meridional flow allows moisture to penetrate at a lower elevation leading to a lower rainout effect. This means zonal flow results in drier conditions in eastern Washington and the converse for meridional flow. We hypothesized that more depleted precipitation δ18O values will occur with periods of more zonal flow across the PNW and will be recorded by trees at our sites. Results show a strong relationship between our δ18O chronologies and winter precipitation (R = -0.50; p<0.001). δ13C chronologies from the same trees showed a relationship to prior fall/winter (pOct-pDec) precipitation (R = -0.46; p<0.005) suggesting a possible link to antecedent moisture conditions. With a focus on years with clear zonal and meridional flow regimes, we regressed the tree-ring δ18O anomaly against the instrumental record of total precipitation and compared the residual series to records of storm track for the period 1978-2008, and we found a detectable signal where the most depleted δ18O was generally associated with zonal flow and the most enriched δ18O with meridional flow. However, there are still some years where the relationship is unclear. Further work is aimed at understanding these anomalous years and extending our record beyond the instrumental

  5. Reconciling single chamber Mg/Ca with whole test δ18O in surface to deep dwelling planktonic foraminifera from the Mozambique Channel

    Directory of Open Access Journals (Sweden)

    J. Steinhardt

    2014-12-01

    Full Text Available Most planktonic foraminifera migrate vertically through the water column during life, meeting a range of depth-related conditions as they grow and calcify. For reconstructing past ocean conditions from geochemical signals recorded in their shells it is therefore necessary to know vertical habitat preferences. Species with a shallow habitat and limited vertical migration will reflect conditions of the surface mixed layer and short- and meso-scale (i.e. seasonal perturbations therein. Species spanning a wider range of depth habitats, however, will contain a more heterogeneous, intra-specimen variability (i.g. Mg/Ca and δ18O, which is less for species calcifying below the seasonal mixed layer (SML. Here we present results on single-chamber Mg/Ca combined with single shell δ18O and δ13C of surface water Globigerinoides ruber, the thermocline-dwelling Neogloboquadrina dutertrei and Pulleniatina obliquiloculata and the deep dweller Globorotalia scitula from the Mozambique Channel. Species-specific Mg/Ca, δ13C and δ18O data combined with a depth-resolved mass balance model confirm distinctive migration and calcification patterns for each species as a function of hydrography. Whereas single specimen δ18O not always reveal changes in depth habitat related to hydrography (i.g. temperature, measured Mg/Ca of the last chambers can only be explained by active migration in response to changes in temperature stratification. Since species show different responses to changes in hydrography, their shell chemistry can be used to reconstruct different components of the past ocean climate system such as seasonality and depth stratification. Here we present combined single-specimen δ18O and single-chamber Mg/Ca measurements for different species, providing a composite of thermocline and sub-thermocline conditions. These results allow for species-specific reconstruction of calcification depths, using a mass balance model, of four species of planktonic

  6. Maintaining consistent traceability in high-precision isotope measurements of CO2: a way to verify atmospheric trends of δ13C and δ18O

    Directory of Open Access Journals (Sweden)

    L. Huang

    2013-07-01

    Full Text Available Maintaining consistent traceability of high-precision measurements of CO2 isotopes is critical in order to obtain accurate atmospheric trends of δ13C and δ18O (in CO2. Although a number of laboratories/organizations around the world have been conducting baseline measurements of atmospheric CO2 isotopes for several decades, reports on the traceability and maintenance are rare. In this paper, a principle and an approach for maintaining consistent traceability in high-precision isotope measurements (δ13C and δ18O of atmospheric CO2 are described. The concept of Big Delta is introduced and its role in maintaining traceability of the isotope measurements is described and discussed extensively. The uncertainties of the traceability have been estimated based on annual calibration records over the last 10 yr. The overall uncertainties of CO2 isotope measurements for individual ambient samples analyzed by the program at Environment Canada have been estimated (excluding these associated with the sampling. The values are 0.02 and 0.05‰ in δ13C and δ18O, respectively, which are close to the World Meteorological Organization (WMO targets for data compatibility. The annual rates of change in δ13C and δ18O of the primary anchor (which links the flask measurements back to the VPDB-CO2 scale are close to zero (−0.0016 ± 0.0012‰, and −0.006 ± 0.003‰ per year, respectively over a period of 10 yr (2001–2011. The average annual changes of δ13C and δ18O in air CO2 at Alert GAW station over the period from 1999 to 2010 have been evaluated and confirmed; they are −0.025 ± 0.003‰ and 0.000 ± 0.010‰, respectively. The results are consistent with a continuous contribution of fossil fuel CO2 to the atmosphere, having a trend toward more negative in δ13C, whereas the lack of change in δ18O likely reflects the influence from the global hydrologic cycle. The total change of δ13C and δ18O during this period is ~0.27‰ and ~0.00

  7. High-resolution climate variability of southwest China during 57―70 ka reflected in a stalagmite δ18O record from Xinya Cave

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A 26-cm-long stalagmite (XY2) from Xinya Cave in northeastern Chongqing of China has been ICP-MS 230Th/U dated, showing a depositional hiatus at 2.3 cm depth from the top. The growth of the 2.3―26 cm interval determined by four dates was between 57 ka and 70 ka, with a linear growth rate of 0.023 mm/a. We have analyzed 190 samples for δ 18O and δ 13C, mostly in the 2.3―26 cm part. The δ 18O and δ 13C values between 57 ka and 70 ka reveal decadal-to-centennial climatic variability during the glacial in-terval of Marine Isotope Stage 4 (MIS4), exhibiting much higher resolution than that of the published Hulu and Dongge records during this interval. Speleothem δ 18O in eastern China, including our study area can be used as a proxy of summer monsoon strength, with lighter values pointing to stronger summer monsoon and higher precipitation, and vice versa. Two decreases in the δ 18O signature of XY2 record around 59.5 and 64.5 Ka are argued to correspond to the Dansgaard-Oeschger (D-O) events 17 and 18 respectively. The Heinrich event 6 (H6) can be identified in the record as a heavy δ 18O peak around 60 ka, indicating significant weakening of the monsoon in Chongqing during the cold period. The XY2 δ 18O record shows very rapid change toward to the interstadial condition of the D-O event, but more gradual change toward to the cold stadial condition. This phenomenon found in the Greenland ice core records is rarely observed so clearly in previously published speleothem records. According to SPECMAP δ 18O record, the glacial maximum of MIS 4 was around 64.5 ka with the boundary of MIS 3/4 around 60 ka. Unlike the marine record, the speleothem record of XY2, China, exhibits much high fre-quency variations without an apparent glacial maximum during MIS 4. However, the timing of MIS 3/4 boundary seems to be around 60 ka when the H6 terminated, in agreement with the marine chronology. The growth period of sample XY2 during glacial times probably reflects a local

  8. High-resolution climate variability of southwest China during 57-70 ka reflected in a stalagmite δ18O record from Xinya Cave

    Institute of Scientific and Technical Information of China (English)

    LI TingYong; LIN YuShi; YUAN DaoXian; LI HongChun; YANG Yan; WANG JianLi; WANG XinYa; LI JunYun; QIN JiaMing; ZHANG MeiLiang

    2007-01-01

    A 26-cm-long stalagmite (XY2) from Xinya Cave in northeastern Chongqing of China has been ICP-MS 230Th/U dated, showing a depositional hiatus at 2.3 cm depth from the top. The growth of the 2.3-26 cm interval determined by four dates was between 57 ka and 70 ka, with a linear growth rate of 0.023 mm/a.We have analyzed 190 samples for δ18O and δ13C, mostly in the 2.3-26 cm part. The δ18O and δ13C values between 57 ka and 70 ka reveal decadal-to-centennial climatic variability during the glacial interval of Marine Isotope Stage 4 (MIS4), exhibiting much higher resolution than that of the published Hulu and Dongge records during this interval. Speleothem δ18O in eastern China, including our study area can be used as a proxy of summer monsoon strength, with lighter values pointing to stronger summer monsoon and higher precipitation, and vice versa. Two decreases in the δ18O signature of XY2 record around 59.5 and 64.5 Ka are argued to correspond to the Dansgaard-Oeschger (D-O) events 17 and 18 respectively. The Heinrich event 6 (H6) can be identified in the record as a heavy δ18O peak around 60 ka, indicating significant weakening of the monsoon in Chongqing during the cold period.The XY2 δ18O record shows very rapid change toward to the interstadial condition of the D-O event, but more gradual change toward to the cold stadial condition. This phenomenon found in the Greenland ice core records is rarely observed so clearly in previously published speleothem records. According to SPECMAP δ18O record, the glacial maximum of MIS 4 was around 64.5 ka with the boundary of MIS 3/4 around 60 ka. Unlike the marine record, the speleothem record of XY2, China, exhibits much high frequency variations without an apparent glacial maximum during MIS 4. However, the timing of MIS 3/4 boundary seems to be around 60 ka when the H6 terminated, in agreement with the marine chronology.The growth period of sample XY2 during glacial times probably reflects a local karstic routing

  9. Temporal and spatial variations of δ15N and δ18O for atmospheric N2O above the oceanic surface from Shanghai to Antarctica

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    During the 22nd Chinese Antarctic Research Expedition (CHINARE-22), the atmospheric gas samples above the oceanic surface and near the surface were collected on the track for the scientific ship "Xuelong" and on Millor Peninsula of eastern Antarctica, respectively, using the Tedlar gas bags. Every day the sampling times were 10:00 and 22:00 (local time), respectively. In the laboratory, high-precision measurement of the isotopic compositions for N2O in these gas samples was conducted using Thermo Finnigan MAT-253 Isotopic Mass Spectrometer with a fully automated interface for the pre-GC concen-tration (PreCon) of trace gases. The temporal and spatial variations of δ 15N and δ 18O in atmospheric N2O were analyzed. The mean δ 15N and δ 18O-N2O values above the oceanic surface were (7.21±0.50)‰ and (44.52±0.52)‰, respectively. From 30°N to Antarctica, the δ 15N (6.05‰―7.88‰) linearly increased with the rate of about 0.01‰ with the latitude while the δ 18O (43.05‰―48.78‰) showed a large fluctua-tion. The δ 15N negatively correlated with air temperature and N2O concentration, and slightly positively correlated with δ 18O. The summertime variations of δ 15N and δ 18O-N2O appeared the same trend on Millor Peninsula of eastern Antarctica. They significantly positively correlated with each other and negatively with N2O concentration. The δ 15N and δ 18O-N2O at different sites averaged (7.42±0.35)‰ and (44.69±0.49)‰, respectively, slightly higher than those above the oceanic surface, significantly higher than those of atmospheric N2O in the low-latitude regions of Northern Hemisphere. The predominant factors affecting the spatial variations of δ 15N and δ 18O values were also discussed. The isotopic data given in this study can help to investigate the global and regional N2O budgets.

  10. Archaean fluid-assisted crustal cannibalism recorded by low δ18O and negative ɛHf(T) isotopic signatures of West Greenland granite zircon

    Science.gov (United States)

    Hiess, Joe; Bennett, Vickie C.; Nutman, Allen P.; Williams, Ian S.

    2011-06-01

    The role of fluids during Archaean intra-crustal magmatism has been investigated via integrated SHRIMP U-Pb, δ18O and LA-MC-ICPMS 176Hf isotopic zircon analysis. Six rock samples studied are all from the Nuuk region (southern West Greenland) including two ~3.69 Ga granitic and trondhjemitic gneisses, a 3.64 Ga granitic augen gneiss, a 2.82 Ga granodioritic Ikkattoq gneiss, a migmatite with late Neoarchaean neosome and a homogeneous granite of the 2.56 Ga Qôrqut Granite Complex (QGC). All zircon grains were thoroughly imaged to facilitate analysis of magmatic growth domains. Within the zircon analysed, there is no evidence for metamictization. Initial ɛHf zircon values ( n = 63) are largely sub-chondritic, indicating the granitic host magmas were generated by the remelting of older, un-radiogenic crustal components. Zircon from some granite samples displays more than one 207Pb/206Pb age, and correlated with 176Hf/177Hf compositions can trace multiple phases of remelting or recrystallization during the Archaean. Model ages calculated using Lu/Hf arrays for each sample indicate that the crustal parental rocks to the granites, granodiorites and trondhjemites segregated from a chondrite-like reservoir at an earlier time during the Archaean, corresponding to known formation periods of more primitive tonalite-trondhjemite-granodiorite (TTG) gneisses. Zircon from the ~3.69 Ga granite, the migmatite and QGC granite contains Eoarchaean cores with chondritic 176Hf/177Hf and mantle-like δ18O compositions. The age and geochemical signatures from these inherited components are identical to those of surrounding tonalitic gneisses, further suggesting genesis of these granites by remelting of broadly tonalitic protoliths. Zircon oxygen isotopic compositions ( n = 62) over nine age populations (six igneous and three inherited) have weighted mean or mean δ18O values ranging from 5.8 ± 0.6 to 3.7 ± 0.5‰. The 3.64 Ga granitic augen gneiss sample displays the highest δ18O with

  11. Mesures conjointes des rapports Sr/Ca et δ 18O effectuées sur Acropora nobilis et Pontes lutea: le paléothermomètre Sr/Ca est-il toujours fiable?

    Science.gov (United States)

    Boiseau, Muriel; Cornu, Hélène; Turpin, Laurent; Juillet-Leclerc, Anne

    1997-11-01

    We measured the Sr/Ca and 18O/ 16O ratios in Acropora nobilis and Porites lutea, from the Mayotte lagoon. As the variations of δ 18O seawater are negligible, coral δ 18O aragonite reflects only seasonal temperature variations. While there is a good agreement between the Sr/Ca ratio and δ 18O for Acropora nobilis, it is not the case for Porites lutea. Coral biological and environmental parameters cannot explain the discrepancies between Sr/Ca ratios and isotopic measurements. However, transport mechanisms of Sr 2+ and Ca 2+ and the presence of two mineralogical structures of strontium may affect the Sr/Ca ratio.

  12. Synthesis of porous LiFe0.2Mn1.8O4 with high performance for lithium-ion battery

    International Nuclear Information System (INIS)

    Highlights: • Porous LiFe0.2Mn1.8O4 was fabricated with P123 as a template through a nitrate decomposition method • A high rate capacity and cycling stability were demonstrated when used as cathode in LIBs • This strategy is expected to fabricate other multiple metal oxides with porous structures - Abstract: A facile and effective route was developed for the fabrication of LiFe0.2Mn1.8O4 with porous structures by using Pluronic P-123 as a soft template, based on a nitrate decomposition method. The resultant LiFe0.2Mn1.8O4 was characterized by XRD, SEM, as well as N2 adsorption/desorption measurements which showed a porous structure with a pore size centered at 20 nm. When used as cathode materials in lithium battery, the as-synthesized LiFe0.2Mn1.8O4 exhibited a discharge capacity of 122 mAh g−1 at 1 C and 102 mAh g−1 at 5 C. Moreover, after 500 cycles, the capacity retention (108 mAh g−1) reached 88% of the initial capacity at 1 C. As compared with conventional cathode LiMn2O4, the high performance is believed to originate from the combined effects of porous structure, iron doping and highly crystalline nature of the obtained LiFe0.2Mn1.8O4. This strategy is expected to allow the fabrication of other multiple metal oxides with porous structures for high performance cathode materials

  13. Prediction of plant vulnerability to salinity increase in a coastal ecosystem by stable isotopic composition (δ18O) of plant stem water: a model study

    Science.gov (United States)

    Zhai, Lu; Jiang, Jiang; DeAngelis, Don; Sternberg, Leonel d.S.L

    2016-01-01

    Sea level rise and the subsequent intrusion of saline seawater can result in an increase in soil salinity, and potentially cause coastal salinity-intolerant vegetation (for example, hardwood hammocks or pines) to be replaced by salinity-tolerant vegetation (for example, mangroves or salt marshes). Although the vegetation shifts can be easily monitored by satellite imagery, it is hard to predict a particular area or even a particular tree that is vulnerable to such a shift. To find an appropriate indicator for the potential vegetation shift, we incorporated stable isotope 18O abundance as a tracer in various hydrologic components (for example, vadose zone, water table) in a previously published model describing ecosystem shifts between hammock and mangrove communities in southern Florida. Our simulations showed that (1) there was a linear relationship between salinity and the δ18O value in the water table, whereas this relationship was curvilinear in the vadose zone; (2) hammock trees with higher probability of being replaced by mangroves had higher δ18O values of plant stem water, and this difference could be detected 2 years before the trees reached a tipping point, beyond which future replacement became certain; and (3) individuals that were eventually replaced by mangroves from the hammock tree population with a 50% replacement probability had higher stem water δ18O values 3 years before their replacement became certain compared to those from the same population which were not replaced. Overall, these simulation results suggest that it is promising to track the yearly δ18O values of plant stem water in hammock forests to predict impending salinity stress and mortality.

  14. Impact of source region on the δ18O signal in snow: A case study from Mount Wrangell Alaska

    Science.gov (United States)

    Moore, Kent; Field, Robert; Benson, Carl

    2016-04-01

    The stable isotopic composition of water in ice cores is an important source of information on past climate variability. At its simplest level, the underlying assumption is that there is an empirical relationship between the normalized difference in the concentration for these stable isotopes and a specified local temperature at the ice core site. There are however non-local processes, such as a change in source region or a change in the atmospheric pathway, that can impact the stable isotope signal thereby complicating its use as a proxy for temperature. Here we investigate the importance of these non-local processes through the analysis of the synoptic-scale circulation during a snowfall event at the summit of Mount Wrangell, in south-central Alaska just to the east of the Gulf of Alaska. During this event there was, over a one-day period in which the local temperature was approximately constant, a change in δ18O that exceeded half that normally seen to occur between summer and winter in the region. As we shall show, this arose from a change in the source region, from the sub-tropical eastern Pacific to northeastern Asia for the snow that fell on Mount Wrangell during the event. The recognition that non-local processes play a role in the stable isotope record from the Gulf of Alaska region suggests that these records, in addition to a local temperature signal, also contain signals of large-scale modes of climate variability that impact the North Pacific region such as the Pacific North America teleconnection and the El-Nino Southern Oscillation.

  15. The chronology for the d18O record from Devils Hole, Nevada, extended into the Mid-Holocene

    Science.gov (United States)

    Landwehr, J.M.; Sharp, W.D.; Coplen, T.B.; Ludwig, K. R.; Winograd, I.J.

    2011-01-01

    This report presents the numeric values for the chronology of the paleoclimatically relevant mid-to-late Pleistocene record of the ratios of stable oxygen isotope (delta18O) in vein calcite from Devils Hole, Nev., which recently had been extended into the mid-Holocene. Dating was obtained using 230Th-234U-238U thermal ionization mass spectrometry. Devils Hole is a subaqueous cave of tectonic origin, which developed in the discharge zone of a regional aquifer in south-central Nevada. The primary groundwater recharge source area is the Spring Mountains, the highest mountain range in southern Nevada [altitude 3,630 meters (m)], approximately 80 kilometers to the east of the cavern. The walls of the open fault zone comprising the cave system are coated with dense vein calcite precipitated from the through-flowing groundwater. The calcite, up to 40 centimeters (cm) thick, contains a continuous record of the sequential variation of the composition of stable oxygen isotopes in the ground water over time. The vein calcite has also proven to be a suitable material for precise uranium-series dating via thermal ionization mass spectrometry utilizing the 230Th-234U-238U decay clock. Earlier work has presented data from the Devils Hole core DH-11, a 36-cm-long core of vein calcite recovered from a depth of about 30 m below the water table (about 45 m beneath the ground surface). The DH-11 core provided a continuous record of isotopic oxygen variation from 567,700 to 59,800 years before present. Recent work has extended this record up to 4,500 years before present, into the mid-Holocene epoch.

  16. The influence of clouds and diffuse radiation on ecosystem-atmosphere CO2 and CO18O exhanges

    Energy Technology Data Exchange (ETDEWEB)

    Still, C.J.; Riley, W.J.; Biraud, S.C.; Noone, D.C.; Buenning, N.H.; Randerson, J.T.; Torn, M.S.; Welker, J.; White, J.W.C.; Vachon, R.; Farquhar, G.D.; Berry, J.A.

    2009-05-01

    This study evaluates the potential impact of clouds on ecosystem CO{sub 2} and CO{sub 2} isotope fluxes ('isofluxes') in two contrasting ecosystems (a broadleaf deciduous forest and a C{sub 4} grassland), in a region for which cloud cover, meteorological, and isotope data are available for driving the isotope-enabled land surface model, ISOLSM. Our model results indicate a large impact of clouds on ecosystem CO{sub 2} fluxes and isofluxes. Despite lower irradiance on partly cloudy and cloudy days, predicted forest canopy photosynthesis was substantially higher than on clear, sunny days, and the highest carbon uptake was achieved on the cloudiest day. This effect was driven by a large increase in light-limited shade leaf photosynthesis following an increase in the diffuse fraction of irradiance. Photosynthetic isofluxes, by contrast, were largest on partly cloudy days, as leaf water isotopic composition was only slightly depleted and photosynthesis was enhanced, as compared to adjacent clear sky days. On the cloudiest day, the forest exhibited intermediate isofluxes: although photosynthesis was highest on this day, leaf-to-atmosphere isofluxes were reduced from a feedback of transpiration on canopy relative humidity and leaf water. Photosynthesis and isofluxes were both reduced in the C{sub 4} grass canopy with increasing cloud cover and diffuse fraction as a result of near-constant light limitation of photosynthesis. These results suggest that some of the unexplained variation in global mean {delta}{sup 18}O of CO{sub 2} may be driven by large-scale changes in clouds and aerosols and their impacts on diffuse radiation, photosynthesis, and relative humidity.

  17. Rock Deformation, Component Migration and 18O/16O Variations during Mylonitization in the Southern Tan-Lu Fault Belt

    Institute of Scientific and Technical Information of China (English)

    YANG Xiaoyong; LIU Deliang; FENG Min; YU Qingni; WANG Kuiren

    2007-01-01

    This paper discusses the relationship between the volume loss, fluid flow and component variations in the ductile shear zone of the southern Tan-Lu fault belt. The results show that there is a large amount of fluids flowing through the shear zone during mylonitization, accompanied with the loss of volume of rocks and variations of elements and oxygen isotopes. The calculated temperature for mylonitization in different mylonites ranges from 446 to 484℃, corresponding to that of 475 to 500℃for the wall rocks. The condition of differential stress during mylonization has been obtained between 99 and 210 MPa, whereas the differential stress in the wall rock gneiss is 70-78 MPa. The mylonites are enriched by factors of 1.32-1.87 in elements such as TiO2, P2O5, MnO, Y, Zr and V and depleted in SiO2, Na2O, K2O, Al2O3, Sr, Rb and light REEs compared to their protolith gneiss. The immobile element enrichments are attributed to enrichments in residual phases such as ilmentite, zircon, apatite and epidote in mylonites and are interpreted as due to volume losses from 15% to 60% in the ductile shear zone. The largest amount of SiO2 loss is 35.76 g/100 g in the ductile shear zone, which shows the fluid infiltration. Modeling calculated results of the fluid/rock ratio for the ductile shear zone range from 196 to 1192 by assuming different degrees of fluid saturation. Oxygen isotope changes of quartz and feldspar and the calculated fluid are corresponding to the variations of differential flow stress in the ductile shear zone. With increasing differential flow stress, the mylonites show a slight decrease of δ18O in quartz, K-feldspar and fluid.

  18. Plasma proteome response to severe burn injury revealed by 18O-labeled "universal" reference-based quantitative proteomics.

    Science.gov (United States)

    Qian, Wei-Jun; Petritis, Brianne O; Kaushal, Amit; Finnerty, Celeste C; Jeschke, Marc G; Monroe, Matthew E; Moore, Ronald J; Schepmoes, Athena A; Xiao, Wenzhong; Moldawer, Lyle L; Davis, Ronald W; Tompkins, Ronald G; Herndon, David N; Camp, David G; Smith, Richard D

    2010-09-01

    A burn injury represents one of the most severe forms of human trauma and is responsible for significant mortality worldwide. Here, we present the first quantitative proteomics investigation of the blood plasma proteome response to severe burn injury by comparing the plasma protein concentrations of 10 healthy control subjects with those of 15 severe burn patients at two time-points following the injury. The overall analytical strategy for this work integrated immunoaffinity depletion of the 12 most abundant plasma proteins with cysteinyl-peptide enrichment-based fractionation prior to LC-MS analyses of individual patient samples. Incorporation of an 18O-labeled "universal" reference among the sample sets enabled precise relative quantification across samples. In total, 313 plasma proteins confidently identified with two or more unique peptides were quantified. Following statistical analysis, 110 proteins exhibited significant abundance changes in response to the burn injury. The observed changes in protein concentrations suggest significant inflammatory and hypermetabolic response to the injury, which is supported by the fact that many of the identified proteins are associated with acute phase response signaling, the complement system, and coagulation system pathways. The regulation of approximately 35 proteins observed in this study is in agreement with previous results reported for inflammatory or burn response, but approximately 50 potentially novel proteins previously not known to be associated with burn response or inflammation are also found. Elucidating proteins involved in the response to severe burn injury may reveal novel targets for therapeutic interventions as well as potential predictive biomarkers for patient outcomes such as multiple organ failure.

  19. Temporal and spatial variations of δ15N and δ18O for atmospheric N2O above the oceanic surface from Shanghai to Antarctica

    Institute of Scientific and Technical Information of China (English)

    ZHU RenBin; LIU YaShu; XU Hua; MA Jing; SUN LiGuang

    2008-01-01

    During the 22nd Chinese Antarctic Research Expedition (CHINARE-22), the atmospheric gas samples above the oceanic surface and near the surface were collected on the track for the scientific ship "Xuelong" and on Millor Peninsula of eastern Antarctica, respectively, using the Tedlar gas bags. Every day the sampling times were 10:00 and 22:00 (local time), respectively. In the laboratory, high-precision measurement of the isotopic compositions for N2O in these gas samples was conducted using Thermo Finnigan MAT-253 Isotopic Mass Spectrometer with a fully automated interface for the pre-GC concen-tration (PreCon) of trace gases. The temporal and spatial variations of δ15N and δ18O in atmospheric N2O were analyzed. The mean δ15N and δ18O-N2O values above the oceanic surface were (7.21±0.50)‰ and (44.52±0.52)‰, respectively. From 30°N to Antarctica, the δ15N (6.05%o-7.88‰) linearly increased with the rate of about 0.01‰ with the latitude while the δ18o (43.05‰-48.78‰) showed a large fluctua-tion. The δ15N negatively correlated with air temperature and N2O concentration, and slightly positively correlated with δ18O. The summertime variations of δ15N and δ18O-N2O appeared the same trend on Millor Peninsula of eastern Antarctica. They significantly positively correlated with each other and negatively with N2O concentration. The δ15N and δ18O-N2O at different sites averaged (7.42±0.35)‰ and (44.69±0.49)‰, respectively, slightly higher than those above the oceanic surface, significantly higher than those of atmospheric N2O in the low-latitude regions of Northern Hemisphere. The predominant factors affecting the spatial variations of δ15N and δ180 values were also discussed. The isotopic data given in this study can help to investigate the global and regional N2O budgets.

  20. Using δ15 N- and δ18 O-NO to Evaluate Mechanisms of Nitric Oxide Production Following the Wetting of Dry Soil

    Science.gov (United States)

    Homyak, P. M.; Schimel, J.; Sickman, J. O.

    2014-12-01

    In xeric environments, where soils can remain dry for more than 6 months, abrupt transitions from dry-to-wet conditions produce NO pulses within seconds after soils wet up. During these periods of intense gaseous N production, biological processes (nitrification and denitrification) are known to control NO fluxes, but it is not clear how soil microbes can recover from drought-induced stress within seconds after soils wet up. Are NO pulses immediately following rewetting more so controlled by abiotic NO-producing reactions? Because biotic and abiotic mechanisms can occur simultaneously, distinguishing between these processes can be problematic. To understand the contribution of biotic and abiotic processes to NO pulses, and to better inform biogeochemical models, we measured the δ15N- and δ18O-NO following a field soil rewetting experiment in a California annual grassland. In October, during the end of the dry season, we artificially watered soils and captured NO emissions for up to 15 minutes, 1 hour, 1 day, and 3 days after wet-up. Pulses of NO following the wetting of dry soil were explained by a two-component mixing model, where two distinct sources or processes produced NO. Within 15 minutes after soil wet-up, the isotopic composition of soil NO (δ15N =-8.95 ‰, δ18O=14.28 ‰) was similar to that of atmospheric samples (δ15N =-4.45 ‰, δ18O=15.20 ‰), but became increasingly depleted after 1 hour (δ15N =-21.08 ‰, δ18O=0.53 ‰), and more so after 1 day (δ15N =-37.44 ‰, δ18O=-9.45 ‰). After 3 days, the isotopic composition of NO (δ15N =-28.31 ‰, δ18O=-2.07 ‰) began to return to pre-wet-up conditions closely following the two-component mixing line. We conclude that NO-producing reactions immediately after the wetting of dry soil (up to 15 min) are different than those occurring after 1 hour post-wetting. We hypothesize that abiotic processes control the initial response to wetting, but that biological processes, which discriminate

  1. Identification and correction of spectral contamination in 2H/1H and 18O/16O measured in leaf, stem, and soil water.

    Science.gov (United States)

    Schultz, Natalie M; Griffis, Timothy J; Lee, Xuhui; Baker, John M

    2011-11-15

    Plant water extracts typically contain organic materials that may cause spectral interference when using isotope ratio infrared spectroscopy (IRIS), resulting in errors in the measured isotope ratios. Manufacturers of IRIS instruments have developed post-processing software to identify the degree of contamination in water samples, and potentially correct the isotope ratios of water with known contaminants. Here, the correction method proposed by an IRIS manufacturer, Los Gatos Research, Inc., was employed and the results were compared with those obtained from isotope ratio mass spectrometry (IRMS). Deionized water was spiked with methanol and ethanol to create correction curves for δ(18)O and δ(2)H. The contamination effects of different sample types (leaf, stem, soil) and different species from agricultural fields, grasslands, and forests were compared. The average corrections in leaf samples ranged from 0.35 to 15.73‰ for δ(2)H and 0.28 to 9.27‰ for δ(18)O. The average corrections in stem samples ranged from 1.17 to 13.70‰ for δ(2)H and 0.47 to 7.97‰ for δ(18)O. There was no contamination observed in soil water. Cleaning plant samples with activated charcoal had minimal effects on the degree of spectral contamination, reducing the corrections, by on average, 0.44‰ for δ(2)H and 0.25‰ for δ(18)O. The correction method eliminated the discrepancies between IRMS and IRIS for δ(18)O, and greatly reduced the discrepancies for δ(2)H. The mean differences in isotope ratios between IRMS and the corrected IRIS method were 0.18‰ for δ(18)O, and -3.39‰ for δ(2)H. The inability to create an ethanol correction curve for δ(2)H probably caused the larger discrepancies. We conclude that ethanol and methanol are the primary compounds causing interference in IRIS analyzers, and that each individual analyzer will probably require customized correction curves. PMID:22006400

  2. Energy loss straggling data of 28Si, 27Al, 24Mg, 19F, 16O, and 12C heavy ions in thin polymeric Formvar foil over a range of energies 0.1–0.6 MeV/u by time-of-flight spectrometry

    International Nuclear Information System (INIS)

    The energy-loss straggling of 28Si, 27Al, 24Mg, 19F, 16O and 12C partially stripped heavy ions has been determined in Formvar polymeric thin foil over a continuous range of energies 0.1–0.6 MeV/u, by using a powerful method based on the combination of Heavy Ion-Elastic Recoil Detection Analysis (HI-ERDA) technique and Time of Flight (ToF) spectrometer. The obtained energy loss straggling values have been analyzed and compared with the corresponding computed values adopting some widely used energy loss straggling formulations such as, Bohr, Bethe–Livingston and Yang formulas. The aim of such a comparison is to check the reliability and accuracy of the existing energy loss straggling formulations. The experimental results of energy loss straggling of all ions are found to be significantly greater than those predicted by the theories. These differences can be attributed to the charge exchange straggling. This effect has to be taken into account in order to explain the obtained results. - Highlights: • Measurement of energy loss straggling data of 28Si, 27Al, 24Mg, 19F, 16O, and 12C heavy ions in thin polymeric Formvar foil. • The heavy ion elastic recoil detection analysis (HIERDA) technique coupled with time of flight (ToF) spectrometer was used. • The aim of such a study is to check the reliability and accuracy of the existing energy loss straggling formulations

  3. Kinetics of oxygen-18 exchange between inorganic phosphate and water catalyzed by myosin subfragment 1, using the 18O shift in 31P NMR.

    Science.gov (United States)

    Webb, M R; McDonald, G G; Trentham, D R

    1978-05-10

    The time course of oxygen-18 exchange between [18O]Pi and normal water, catalyzed by myosin subfragment 1 in the presence of MgADP, was followed using the shift in 31P NMR caused by the presence of oxygen-18 bound to the phosphorus. Essentially all molecules of [18O]Pi that bind to the enzyme undergo complete exchange and are released as [16O4]Pi. Exchange probably occurs by formation of myosin.ATP from a myosin.ADP.Pi complex and is rapid relative to release of Pi from this complex. The kinetics of exchange give a value for the rate constant for binding Pi to myosin.ADP of 0.23 M-1 S-1 (pH 8.0, 22 degrees C). This value is consistent with exchange occurring by reversal of the ATP-ase reaction back to the myosin.ATP complex. PMID:641045

  4. Relationship between isotopic composition (Δ18O and Δ13C and plaktonic foraminifera test size in core tops from the Brazilian Continental Margin

    Directory of Open Access Journals (Sweden)

    Paula Franco-Fraguas

    2011-12-01

    Full Text Available Stable oxygen (δ18O and carbon (δ13C isotopic signature registered in fossil planktonic foraminifera tests are widely used to reconstruct ancient oceanographic conditions. Test size is a major source of stable isotope variability in planktonic foraminifera found in sediment samples and thus can compromise paleoceanographic interpretations. Test size/stable isotope (δ18O and δ13C relationships were evaluated in two planktonic foraminifer species (Globigerinoides ruber (white and Globorotalia truncatulinoides (right in two core tops from the Brazilian Continental Margin. δ18 Omeasurements were used to predict the depth of calcification of each test size fraction. δ13C offsets for each test size fraction were then estimated. No systematic δ18O changes with size were observed in G. ruber (white suggesting a similar calcification depth range (c.a. 100 m during ontogeny. For G. truncatulinoides (right δ18O values increased with size indicating ontogenetic migration along thermocline waters (250-400 m. δ13C measurements and δ13C offsets increased with size for both species reflecting well known physiological induced ontogenetic-related variability. In G. ruber (white the largest test size fractions (300µm and >355µm more closely reflect δ13C DIC indicating they are best suited for paleoceanographic studies.O tamanho de testa dos foraminíferos é uma importante fonte de variabilidade isotópica (δ18O e δ13C em amostras de sedimento marinho comprometendo as interpretações paloeceanograficas. No presente estudo, avaliou-se a relação entre o sinal isotópico medido em diferentes frações de tamanho de testa das espécies planctônicas, Globigerinoides ruber (branca e Globorotalia truncatulinoides (dextral em amostras de topo de dois testemunhos localizados na Margem Continental Brasileira. Os valores de δ18O foram utilizados para estimar a profundidade de calcificação de cada fração de tamanho. Os desequilíbrios nos valores de

  5. The impact of Carbonic Anhydrase on the partitioning of leaf and soil CO18O and COS gas exchange across scales

    Science.gov (United States)

    Wingate, L.; Wehr, R. A.; Commane, R.; Ogee, J.; Sauze, J.; Jones, S.; Launois, T.; Wohl, S.; Whelan, M.; Meredith, L. K.; Genty, B.; Gimeno, T.; Kesselmeier, J.; Bosc, A.; Cuntz, M.; Munger, J. W.; Nelson, D. D.; Saleska, S. R.; Wofsy, S. C.; Zahniser, M. S.

    2015-12-01

    Photosynthesis (GPP), the largest CO2 flux to the land surface, is currently estimated with considerable uncertainty at between 100-175 Pg C yr-1. More robust estimates of global GPP could be obtained from the atmospheric budgets of other valuable tracers, such as carbonyl sulfide (COS) or the oxygen isotopic composition (δ18O) of atmospheric CO2. However, quantifying GPP using these tracers hinges on a better understanding of how soil micro-organisms modify the atmospheric concentrations of CO18O and COS at large scales. In particular, understanding better the role and activity of the enzyme Carbonic Anhydrase (CA) in soil micro-organisms is critical. We present novel datasets and model simulations demonstrating the progress in the collection of multi-tracer field datasets and how a new generation of multi-tracer land surface models can provide valuable constraints on photosynthesis and respiration across scales.

  6. Eocene-Oligocene proto-Cascades topography revealed by clumped (Δ47) and oxygen isotope (δ18O) geochemistry (Chumstick Basin, WA, USA)

    Science.gov (United States)

    Methner, Katharina; Fiebig, Jens; Wacker, Ulrike; Umhoefer, Paul; Chamberlain, C. Page; Mulch, Andreas

    2016-03-01

    The topography of the present-day Washington Cascades impacts atmospheric circulation and precipitation patterns in the Pacific Northwest, introducing a pronounced orographic rain shadow in the lee of the mountain range. The temporal development of Cascade topography, however, remains largely unconstrained for the early Cenozoic. Based on coupled carbonate clumped isotope (Δ47) and oxygen isotope (δ18O) measurements we reconstruct δ18O values of Eocene groundwater (δ18Owater) in the Chumstick basin (central Washington), today located in the Cascade rain shadow. Δ47 (paleo)thermometry indicates a systematic change in basin burial temperatures from 110°C to 70°C depending on burial depth in the basin. These data are in good agreement with low-T thermochronological and vitrinite reflectance data, and further constrain the basin burial and exhumation history. In concert with field observations, microstructural analysis, and δ18O values of the analyzed carbonates, we suggest that the Δ47 temperatures and δ18O values reflect open-system carbonate cement recrystallization in meteoric-derived groundwaters during early burial diagenesis. Assuming open-system behavior, reconstructed mean δ18Owater values of ~ -7‰ (middle Eocene) to -9‰ (late Eocene/early Oligocene) are consistent with a low-elevation origin of the corresponding meteoric waters that permeated the sandstone/conglomerate members of the Eocene sedimentary units. In light of the paleogeographic setting of the Chumstick basin, the reconstructed δ18Owater values agree well with Pacific-derived moisture that did not experience strong rainout. The absence of a rain shadow effect therefore permits only moderate Eocene/Oligocene elevations at least for the southern part of the Washington proto-Cascades.

  7. Dense cores in dark clouds. 9: Observations of (13)CO and C(18)O in Vela, Chamaeleon, Musca, and the Coalsack

    Science.gov (United States)

    Vilas-Boas, J. W. S.; Myers, P. C.; Fuller, G. A.

    1994-09-01

    One hundred one condensations with average optical size less than 7 min and visual extinction greater than 2.5 mag have been selected from European Southern Observatory (ESO) J plates, extinction maps, and catalogs of southern hemisphere dark clouds for observation in the (13)CO and C(18)O J = 1 goes to 0 transitions. These regions are condensations in the dark molecular clouds Musca, Coalsack, Chamaeleon II, Chamaeleon III, and cometary globules in Vela and Gum nebula. A search for IRAS point sorces having colors of young stellar objects shows that these condensations have at most seven associated young stellar objects-far fewer than in Taurus and Ophiuchus. These 101 condensations generally have lower (13)CO and C(18)O line intensity, C(18)O optical depth, and (13)CO line width than do 90 condensations in Taurus, Ophiuchus, and Cepheus. Similarly, 47 of these southern condensations having star-count estimates of visual extinction generally have less extinction than do the 19 condensations in Taurus having extinction estimated by the same method. The C(18)O to (13)CO line-width ratio for the cometary globules in the Vela ragion is greater than for the other clouds, indicating that the (13)CO line width observed toward dark cloud condensations is related to the more extended and less dense intercondensation gas. Radial velocities suggest that the system of Vela globules has velocity dispersion 4.7 km/s, which is at least 2 times greater than the dispersion determined from formalhyde observations. The Musca filament has velocities which are slightly higher-by approximately 0.5 km/s-in the center than at the ends of the filament. Chamaeleon III has a 0.2 km/s velocity gradient and Chamaeleon II has no indication of velocity gradients. The Chamaeleon clouds and the Musca filament appear close to virial equilibrium.

  8. Tequila authenticity assessment by headspace SPME-HRGC-IRMS analysis of 13C/12C and 18O/16O ratios of ethanol.

    Science.gov (United States)

    Aguilar-Cisneros, Blanca O; López, Mercedes G; Richling, Elke; Heckel, Frank; Schreier, Peter

    2002-12-18

    By use of headspace SPME sampling and a PLOT column, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta(13)C(VPDB) and delta(18)O(VSMOW) values of ethanol in authentic (n = 14) and commercial tequila samples (n = 15) as well as a number of other spirits (n = 23). Whereas with delta(13)C(VPDB) values ranging from -12.1 to -13.2 per thousand and from -12.5 to -14.8 per thousand similar variations were found for 100% agave and mixed tequilas, respectively, the delta(18)O(VSMOW) data differed slightly within these categories: ranges from +22.1 to +22.8 per thousand and +20.8 to +21.7 per thousand were determined for both the authentic 100% agave and mixed products, respectively. The data recorded for commercial tequilas were less homogeneous; delta(13)C(VPDB) data from -10.6 to -13.9 per thousand and delta(18)O(VSMOW) values from +15.5 to +22.7 per thousand were determined in tequilas of both categories. Owing to overlapping data, attempts to differentiate between white, rested, and aged tequilas within each of the two categories failed. In addition, discrimination of tequila samples from other spirits by means of delta(13)C(VPDB) and delta(18)O(VSMOW) data of ethanol was restricted to the products originating from C(3) as well as C(4)/CAM raw materials.

  9. A mechanistic model of H{sub 2}{sup 18}O and C{sup 18}OO fluxes between ecosystems and the atmosphere: Model description and sensitivity analyses

    Energy Technology Data Exchange (ETDEWEB)

    Riley, W.J.; Still, C.J.; Torn, M.S.; Berry, J.A.

    2002-01-01

    The concentration of 18O in atmospheric CO2 and H2O is a potentially powerful tracer of ecosystem carbon and water fluxes. In this paper we describe the development of an isotope model (ISOLSM) that simulates the 18O content of canopy water vapor, leaf water, and vertically resolved soil water; leaf photosynthetic 18OC16O (hereafter C18OO) fluxes; CO2 oxygen isotope exchanges with soil and leaf water; soil CO2 and C18OO diffusive fluxes (including abiotic soil exchange); and ecosystem exchange of H218O and C18OO with the atmosphere. The isotope model is integrated into the land surface model LSM, but coupling with other models should be straightforward. We describe ISOLSM and apply it to evaluate (a) simplified methods of predicting the C18OO soil-surface flux; (b) the impacts on the C18OO soil-surface flux of the soil-gas diffusion coefficient formulation, soil CO2 source distribution, and rooting distribution; (c) the impacts on the C18OO fluxes of carbonic anhydrase (CA) activity in soil and leaves; and (d) the sensitivity of model predictions to the d18O value of atmospheric water vapor and CO2. Previously published simplified models are unable to capture the seasonal and diurnal variations in the C18OO soil-surface fluxes simulated by ISOLSM. Differences in the assumed soil CO2 production and rooting depth profiles, carbonic anhydrase activity in soil and leaves, and the d18O value of atmospheric water vapor have substantial impacts on the ecosystem CO2 flux isotopic composition. We conclude that accurate prediction of C18OO ecosystem fluxes requires careful representation of H218O and C18OO exchanges and transport in soils and plants.

  10. Analysis of stable isotope ratios (δ18O and δ2H) in precipitation of the Verde River watershed, Arizona 2013 through 2014

    Science.gov (United States)

    Beisner, Kimberly R.; Paretti, Nicholas V.; Tucci, Rachel S.

    2016-04-25

    Stable isotope delta values (δ18O and δ2H) of precipitation can vary with elevation, and quantification of the precipitation elevation gradient can be used to predict recharge elevation within a watershed. Precipitation samples were analyzed for stable isotope delta values between 2003 and 2014 from the Verde River watershed of north-central Arizona. Results indicate a significant decrease in summer isotopic values overtime at 3,100-, 4,100-, 6,100-, 7,100-, and 8,100-feet elevation. The updated local meteoric water line for the area is δ2H = 7.11 δ18O + 3.40. Equations to predict stable isotopic values based on elevation were updated from previous publications in Blasch and others (2006), Blasch and Bryson (2007), and Bryson and others (2007). New equations were separated for samples from the Camp Verde to Flagstaff transect and the Prescott to Chino Valley transect. For the Camp Verde to Flagstaff transect, the new equations for winter precipitation are δ18O = -0.0004z − 8.87 and δ2H = -0.0029z − 59.8 (where z represents elevation in feet) and the summer precipitation equations were not statistically significant. For the Prescott to Chino Valley transect, the new equations for summer precipitation are δ18O = -0.0005z − 3.22 and δ2H = -0.0022z − 27.9; the winter precipitation equations were not statistically significant and, notably, stable isotope values were similar across all elevations. Interpretation of elevation of recharge contributing to surface and groundwaters in the Verde River watershed using the updated equations for the Camp Verde to Flagstaff transect will give lower elevation values compared with interpretations presented in the previous studies. For waters in the Prescott and Chino Valley area, more information is needed to understand local controls on stable isotope values related to elevation.

  11. On the calibration of continuous, high-precision delta18O and delta2H measurements using an off-axis integrated cavity output spectrometer.

    Science.gov (United States)

    Wang, Lixin; Caylor, Kelly K; Dragoni, Danilo

    2009-02-01

    The (18)O and (2)H of water vapor serve as powerful tracers of hydrological processes. The typical method for determining water vapor delta(18)O and delta(2)H involves cryogenic trapping and isotope ratio mass spectrometry. Even with recent technical advances, these methods cannot resolve vapor composition at high temporal resolutions. In recent years, a few groups have developed continuous laser absorption spectroscopy (LAS) approaches for measuring delta(18)O and delta(2)H which achieve accuracy levels similar to those of lab-based mass spectrometry methods. Unfortunately, most LAS systems need cryogenic cooling and constant calibration to a reference gas, and have substantial power requirements, making them unsuitable for long-term field deployment at remote field sites. A new method called Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) has been developed which requires extremely low-energy consumption and neither reference gas nor cryogenic cooling. In this report, we develop a relatively simple pumping system coupled to a dew point generator to calibrate an ICOS-based instrument (Los Gatos Research Water Vapor Isotope Analyzer (WVIA) DLT-100) under various pressures using liquid water with known isotopic signatures. Results show that the WVIA can be successfully calibrated using this customized system for different pressure settings, which ensure that this instrument can be combined with other gas-sampling systems. The precisions of this instrument and the associated calibration method can reach approximately 0.08 per thousand for delta(18)O and approximately 0.4 per thousand for delta(2)H. Compared with conventional mass spectrometry and other LAS-based methods, the OA-ICOS technique provides a promising alternative tool for continuous water vapor isotopic measurements in field deployments. PMID:19142848

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

    Science.gov (United States)

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

    2015-12-01

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

  13. Submillimeter spectroscopy of H$_2$C$^{17}$O and a revisit of the rotational spectra of H$_2$C$^{18}$O and H$_2$C$^{16}$O

    CERN Document Server

    Müller, Holger S P

    2016-01-01

    The rotational spectrum of the formaldehyde isotopologue H2C(17)O was investigated between 0.56 and 1.50 THz using a sample of natural isotopic composition. In addition, transition frequencies were determined for H2C(18)O and H2C(16)O between 1.37 and 1.50 THz. The data were combined with critically evaluated literature data to derive improved sets of spectroscopic parameters which include (17)O or H nuclear hyperfine structure parameters.

  14. Follow-up observations of Planck cold clumps in $^{12}$CO/$^{13}$CO/C$^{18}$O (1--0) transitions

    CERN Document Server

    Wu, Yuefang; Meng, Fanyi

    2012-01-01

    The Planck Early Cold Cores Catalog (ECC) provides an unbiased list of Galactic cold clumps, which form an ideal sample for studying the early phases of star formation (\\cite[Planck Collabrators et al. 2011]{Planck_etal11}). To study their properties, we have carried out a molecular line ($^{12}$CO/$^{13}$CO/C$^{18}$O) survey towards 674 Planck cold clumps in the ECC with the PMO 13.7 m telescope.

  15. The effects of assimilation of country rocks by magmas on 18O/16O and 87Sr/86Sr systematics in igneous rocks

    International Nuclear Information System (INIS)

    Examples of positive correlations between intial 87Sr/86Sr and delta18O have now been shown to be very common in igneous rock series. These data in general require some type of mixing of mantle-derived igneous rocks with high-18O, high-87Sr crustal metamorphic rocks that once resided on or near the Earth's surface, such as sedimentary rocks or hydrothermally altered volcanic rocks. Mixing that involves assimilation of country rocks by magmas, however, is not a simple two-end-member process; heat balance requires appreaciable crystallization of cumulates. In such cases, the isotopic compositions may strongly reflect this open-system behavior and indicate the process of assimilation, whereas the major element chemical compositions of the contaminated magmas will be largely controlled by crystal-melt equilibria and crastallization paths fixed by multicomponent cotectics. A variety of oxygen and strontium isotope mixing curves were therefore calculated for this process of combined assimilation-fractional crystallization. The positions and characteristics of the resultant curves on delta18O-87Sr/86Sr diagrams markedly diverge from simple two end-member mixing relationships. Based on the above, model calculation can be crudely fitted to two igneous rock suites (Adamello and Roccamonfina in Italy), but the shapes of the calculated curves appear to rule out magmatic assimilation as an explanation for most delta18O-87Sr/86Sr correlations discovered so far, including all of those involving calc-alkaline granitic batholiths and andesitic volcanic rocks. The isotopic relationshipfs in such magma types must be inherited from their source regions, resumably reflecting patterns that existed in the parent rocks (or magmas) prior to or during melting. (orig.)

  16. Oxygen isotopes in Indian Plate eclogites (Kaghan Valley, Pakistan): Negative δ18O values from a high latitude protolith reset by Himalayan metamorphism

    Science.gov (United States)

    Rehman, Hafiz Ur; Tanaka, Ryoji; O'Brien, Patrick J.; Kobayashi, Katsura; Tsujimori, Tatsuki; Nakamura, Eizo; Yamamoto, Hiroshi; Khan, Tahseenullah; Kaneko, Yoshiyuki

    2014-11-01

    Oxygen isotope compositions are reported for the first time for the Himalayan metabasites of the Kaghan Valley, Pakistan in this study. The highest metamorphic grades are recorded in the north of the valley, near the India-Asia collision boundary, in the form of high-pressure (HP: Group I) and ultrahigh-pressure (UHP: Group II) eclogites. The rocks show a step-wise decrease in grade from the UHP to HP eclogites and amphibolites. The protoliths of these metabasites were the Permian Panjal Trap basalts (ca. 267 ± 2.4 Ma), which were emplaced along the northern margin of India when it was part of Gondwana. After the break-up of Gondwana, India drifted northward, subducted beneath Asia and underwent UHP metamorphism during the Eocene (ca. 45 ± 1.2 Ma). At the regional scale, amphibolites, Group I and II eclogites yielded δ18O values of + 5.84 and + 5.91‰, + 1.66 to + 4.24‰, and - 2.25 to + 0.76‰, respectively, relative to VSMOW. On a more local scale, within a single eclogite body, the δ18O values were the lowest (- 2.25 to- 1.44‰) in the central, the best preserved (least retrograded) parts, and show a systematic increase outward into more retrograded rocks, reaching up to + 0.12‰. These values are significantly lower than the typical mantle values for basalts of + 5.7 ± 0.3‰. The unusually low or negative δ18O values in Group II eclogites potentially resulted from hydrothermal alteration of the protoliths by interactions with meteoric water when the Indian plate was at southern high latitudes (~ 60°S). The stepwise increase in δ18O values, among different eclogite bodies in general and at single outcrop-scales in particular, reflects differing degrees of resetting of the oxygen isotope compositions during exhumation-related retrogression.

  17. Analysis of stable isotope ratios (δ18O and δ2H) in precipitation of the Verde River watershed, Arizona 2013 through 2014

    Science.gov (United States)

    Beisner, Kimberly R.; Paretti, Nicholas V.; Tucci, Rachel S.

    2016-01-01

    Stable isotope delta values (δ18O and δ2H) of precipitation can vary with elevation, and quantification of the precipitation elevation gradient can be used to predict recharge elevation within a watershed. Precipitation samples were analyzed for stable isotope delta values between 2003 and 2014 from the Verde River watershed of north-central Arizona. Results indicate a significant decrease in summer isotopic values overtime at 3,100-, 4,100-, 6,100-, 7,100-, and 8,100-feet elevation. The updated local meteoric water line for the area is δ2H = 7.11 δ18O + 3.40. Equations to predict stable isotopic values based on elevation were updated from previous publications in Blasch and others (2006), Blasch and Bryson (2007), and Bryson and others (2007). New equations were separated for samples from the Camp Verde to Flagstaff transect and the Prescott to Chino Valley transect. For the Camp Verde to Flagstaff transect, the new equations for winter precipitation are δ18O = -0.0004z − 8.87 and δ2H = -0.0029z − 59.8 (where z represents elevation in feet) and the summer precipitation equations were not statistically significant. For the Prescott to Chino Valley transect, the new equations for summer precipitation are δ18O = -0.0005z − 3.22 and δ2H = -0.0022z − 27.9; the winter precipitation equations were not statistically significant and, notably, stable isotope values were similar across all elevations. Interpretation of elevation of recharge contributing to surface and groundwaters in the Verde River watershed using the updated equations for the Camp Verde to Flagstaff transect will give lower elevation values compared with interpretations presented in the previous studies. For waters in the Prescott and Chino Valley area, more information is needed to understand local controls on stable isotope values related to elevation.

  18. Unveiling stomata 24/7: can we use carbonyl sulfide (COS) and oxygen isotopes (18O) to constrain estimates of nocturnal transpiration across different evolutionary plant forms?

    Science.gov (United States)

    Gimeno, Teresa E.; Ogee, Jerome; Bosc, Alexander; Genty, Bernard; Wohl, Steven; Wingate, Lisa

    2015-04-01

    Numerous studies have reported a continued flux of water through plants at night, suggesting that stomata are not fully closed. Growing evidence indicates that this nocturnal flux of transpiration might constitute an important fraction of total ecosystem water use in certain environments. However, because evaporative demand is usually low at night, nocturnal transpiration fluxes are generally an order of magnitude lower than rates measured during the day and perilously close to the measurement error of traditional gas-exchange porometers. Thus estimating rates of stomatal conductance in the dark (gnight) precisely poses a significant methodological challenge. As a result, we lack accurate field estimates of gnight and how it responds to different atmospheric drivers, indicating the need for a different measurement approach. In this presentation we propose a novel method to obtain detectable and robust estimates of gnight. We will demonstrate using mechanistic theory how independent tracers including the oxygen isotope composition of CO2 (δ18O) and carbonyl sulfide (COS) can be combined to obtain robust estimates of gnight. This is because COS and CO18O exchange within leaves are controlled by the light insensitive enzyme carbonic anhydrase. Thus, if plant stomata are open in the dark we will continue to observe COS and CO18O exchange. Using our theoretical model we will demonstrate that the exchange of these tracers can now be measured using advances in laser spectrometry techniques at a precision high enough to determine robust estimates of gnight. We will also present our novel experimental approach designed to measure simultaneously the exchange of CO18O and COS alongside the conventional technique that relies on measuring the total water flux from leaves in the dark. Using our theoretical approach we will additionally explore the feasibility of our proposed experimental design to detect variations in gnight during drought stress and across a variety of plant

  19. Characterization of biodegradation intermediates of nonionic surfactants by MALDI-MS. 2. Oxidative biodegradation profiles of uniform octylphenol polyethoxylate in 18O-labeled water.

    Science.gov (United States)

    Sato, Hiroaki; Shibata, Atsushi; Wang, Yang; Yoshikawa, Hiromichi; Tamura, Hiroto

    2003-01-01

    This paper reports the characterization of the biodegradation intermediates of octylphenol octaethoxylate (OP(8)EO) by means of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The biodegradation test study was carried out in a pure culture (Pseudomonas putida S-5) under aerobic conditions using OP(8)EO as the sole carbon source and (18)O-labeled water as an incubation medium. In the MALDI-MS spectra of biodegraded samples, a series of OP(n)EO molecules with n = 2-8 EO units and their corresponding carboxylic acid products (OP(n)EC) were observed. The use of purified OP(8)EO enabled one to distinguish the shortened OPEO molecules as biodegradation intermediates. Furthermore, the formation of OP(8)EC (the oxidized product of OP(8)EO) supported the notion that terminal oxidation is a step in the biodegradation process. When biodegradation study was carried out in (18)O-labeled water, incorporation of (18)O atoms into the carboxyl group was observed for OPEC, while no incorporation was observed for the shortened OPEO products. These results could provide some rationale to the biodegradation mechanism of alkylphenol polyethoxylates. PMID:12523845

  20. Abrupt climate change of East Asian Monsoon at 130 kaBP inferred from a high resolution stalagmite δ18O record

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiuyang; WANG Yongjin; KONG Xinggong; WU Jiangying; SHAO Xiaohua; XIA Zhifeng; CHENG Hai

    2005-01-01

    230Th ages and oxygen isotope data of a stalagmite from Shanbao Cave in Hubei Province characterize the East Asian Monsoon precipitation from 133 to127 ka. The decadal-scale high-resolution δ18O record reveals a detailed transitional process from the Penultimate Glaciation to the Last Interglaciation. As established with 230Th dates, the age of the Termination II is determined to be 129.5±1.0 kaBP, which supports the Northern Hemisphere insolation as the triggers for the ice-age cycles. In our δ18O record, the glacial/ interglacial fluctuation reaches about 4‰, almost the same level as in other Asian Monsoon cave stalagmite δ18O records. The transition of the glacial/interglacial period in our record can be recognized as four stepwise stages, among which, a rapid rise of monsoon precipitation follows the stage of "Termination II pause". The rapid rise is synchronous with the abrupt change of global methane concentration, which reflects that an increase in both Asian Monsoon precipitation and tropical wetland plays an important role in the global climate changes.

  1. Determination Of Oxygen Isotope Ratio (18O-/16O) and Sulfur (34S-/32S) Value Of BaSO4 Din 5033 For Internal Standard

    International Nuclear Information System (INIS)

    It has been done an experiment to determine of oxygen(18O-/16O) and Sulfur (34S-/32S) ) isotop value of BaSO4 DIN 5033 (merck) for internal standard. The used technique for preparation of CO2 gas to measure oxygen isotop ratio ratio (stated as deltaδ 18O) is based on Rafter on Rafte method using graphite for reduction of BaSO4. Where the used technique for preparation of SO2 gas to measure isotope sulphur ratio (started as δ 34S) is based on Robinson - Kasakabe method using Cupro oxide to oxidize Ag2S. The result of this experiment is 11,48±0,41 0/00 and 5,00 plus minus ±0,33 o/oo for deltaδ 18O and δ 34S value respectively. Based on this experiment. BaSO4 DIN 5033 can be used as internal standard because is values both oxygen and sulphur lie in the middle of range of its variation in nature. The result of interlab comparison shows that the value of this experiment is nearly similar to the value obtained from laboratorium of Pinstech-Pakistan. To acquire the result, it is necessary to carry out more interlab comparison

  2. Characterization of the water chemistry, sediment (13)C and (18)O compositions of Kolleru Lake-a Ramsar wetland in Andhra Pradesh, India.

    Science.gov (United States)

    Das Sharma, Subrata; Sujatha, D

    2016-07-01

    The chemistry of surface water sampled at different locations of the Kolleru Lake in Andhra Pradesh (India) show heterogeneous variability. The concentrations of dissolved sodium and chloride ions, total dissolved solids (TDS) together with high conductivity documented in water samples are indicative of mixing of saline seawater. This interpretation is further corroborated by enriched δ(18)O compositions of the carbonate fraction of the surface sediments collected at the same locations (as that of water) of the lake, and fairly good positive correlations of δ(18)O -Na(+) and δ(18)O-TDS. The saline water intrusion into the lake appears to be resulted due to its near stagnant to dry condition with reduced inflow and outflow. Such dry condition facilitated seawater intrusion into the lake due to several reasons: (i) proximity of lake to the sea (~35 km), (ii) overexploitation of fresh groundwater for agriculture as well as livestock farming, and (iii) incursion of tidal seawater (high sea waves) through Upputeru River, which is directly linked to the sea. We also document highly heterogeneous distribution of certain potentially toxic metal ions like chromium, copper, manganese, and zinc in the lake waters. Indiscriminate disposal of domestic and industrial effluents around the lake appears to be responsible for the presence of potentially toxic heavy metals. Based on these results, we finally suggest some measures for environmental rehabilitation of the lake and its surroundings. PMID:27312252

  3. Ice Core Depth-Age Relation for Vostok delta-D and Dome Fuji delta-18O Records Based on the Devils Hole Paleotemperature Chronology

    Science.gov (United States)

    Landwehr, Jurate Maciunas

    2002-01-01

    This report presents the data for the Vostok - Devils Hole chronology, termed V-DH chronology, for the Antarctic Vostok ice core record. This depth - age relation is based on a join between the Vostok deuterium profile (D) and the stable oxygen isotope ratio (18O) record of paleotemperature from a calcitic core at Devils Hole, Nevada, using the algorithm developed by Landwehr and Winograd (2001). Both the control points defining the V-DH chronology and the numeric values for the chronology are given. In addition, a plausible chronology for a deformed bottom portion of the Vostok core developed with this algorithm is presented. Landwehr and Winograd (2001) demonstrated the broader utility of their algorithm by applying it to another appropriate Antarctic paleotemperature record, the Antarctic Dome Fuji ice core 18O record. Control points for this chronology are also presented in this report but deemed preliminary because, to date, investigators have published only the visual trace and not the numeric values for the Dome Fuji 18O record. The total uncertainty that can be associated with the assigned ages is also given.

  4. Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon

    Science.gov (United States)

    Bacon, C.R.; Adami, L.H.; Lanphere, M.A.

    1989-01-01

    Partially fused granitoid blocks were ejected in the climactic eruption of Mount Mazama, which was accompanied by collapse of Crater Lake caldera. Quartz, plagioclase, and glass in the granitoids have much lower ??18O values (-3.4 to +4.9???) than any fresh lavas of Mount Mazama and the surrounding region (+5.8 to +7.0???). Oxygen isotope fractionation between phases in granitoids is consistent with equilibrium at T ??? 900??C following subsolidus exchange with hydrothermal fluids of meteoric origin. Assimilation of ??? 10-20% of material similar to these granitoids can account for the O and Sr isotopic compositions of lavas and juvenile pyroclasts derived from the climactic magma chamber, many of which have ??18O values ??? 0.5??? or more lower than comparable lavas of Mount Mazama. The O isotope data provide the only clear evidence for such assimilation because the mineralogy and chemical and radiogenic isotopic compositions of the granitoids (dominantly granodiorite) are similar to those of erupted juvenile magmas. The granitoid blocks from Crater Lake serve as direct evidence for the origin of 18O depletion in large, shallow silicic magma bodies. ?? 1989.

  5. Direct evidence for the origin of low-18O silicic magmas: Quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon

    International Nuclear Information System (INIS)

    Partially fused granitoid blocks were ejected in the climactic eruption of Mount Mazama, which was accompanied by collapse of Crater Lake caldera. Quartz, plagioclase, and glass in the granitoids have much lower δ18O values (-3.4 to +4.9per mille) than any fresh lavas of Mount Mazama and the surrounding region (+5.8 to +7.0per mille). Oxygen isotope fractionation between phases in granitoids is consistent with equilibrium at T≥900deg C following subsolidus exchange with hydrothermal fluids of meteoric origin. Assimilation of ≅ 10-20% of material similar to these granitoids can account for the O and Sr isotopic compositions of lavas and juvenile pyroclasts derived from the climactic magma chamber, many of which have δ18O values ≅ 0.5per mille or more lower than comparable lavas of Mount Mazama. The O isotope data provide the only clear evidence for such assimilation because the mineralogy and chemical and radiogenic isotopic compositions of the granitoids (dominantly granodiorite) are similar to those of erupted juvenile magmas. The granitoid blocks from Crater Lake serve as direct evidence for the origin of 18O depletion in large, shallow silicic magma bodies. (orig.)

  6. Large-Scale Multiplexed Quantitative Discovery Proteomics Enabled by the Use of an 18O-Labeled “Universal” Reference Sample

    Science.gov (United States)

    Qian, Wei-Jun; Liu, Tao; Petyuk, Vladislav A.; Gritsenko, Marina A.; Petritis, Brianne O.; Polpitiya, Ashoka D.; Kaushal, Amit; Xiao, Wenzhong; Finnerty, Celeste C.; Jeschke, Marc G.; Jaitly, Navdeep; Monroe, Matthew E.; Moore, Ronald J.; Moldawer, Lyle L.; Davis, Ronald W.; Tompkins, Ronald G.; Herndon, David N.; Camp, David G.; Smith, Richard D.

    2009-01-01

    The quantitative comparison of protein abundances across a large number of biological or patient samples represents an important proteomics challenge that needs to be addressed for proteomics discovery applications. Herein, we describe a strategy that incorporates a stable isotope 18O-labeled ″universal″ reference sample as a comprehensive set of internal standards for analyzing large sample sets quantitatively. As a pooled sample, the 18O-labeled ″universal″ reference sample is spiked into each individually processed unlabeled biological sample and the peptide/protein abundances are quantified based on 16O/18O isotopic peptide pair abundance ratios that compare each unlabeled sample to the identical reference sample. This approach also allows for the direct application of label-free quantitation across the sample set simultaneously along with the labeling-approach (i.e., dual-quantitation) since each biological sample is unlabeled except for the labeled reference sample that is used as internal standards. The effectiveness of this approach for large-scale quantitative proteomics is demonstrated by its application to a set of 18 plasma samples from severe burn patients. When immunoaffinity depletion and cysteinyl-peptide enrichment-based fractionation with high resolution LC-MS measurements were combined, a total of 312 plasma proteins were confidently identified and quantified with a minimum of two unique peptides per protein. The isotope labeling data was directly compared with the label-free 16O-MS intensity data extracted from the same data sets. The results showed that the 18O reference-based labeling approach had significantly better quantitative precision compared to the label-free approach. The relative abundance differences determined by the two approaches also displayed strong correlation, illustrating the complementary nature of the two quantitative methods. The simplicity of including the 18O-reference for accurate quantitation makes this

  7. A Modern Sr/Ca-δ18O-Sea Surface Temperature Calibration for Isopora Corals in the Great Barrier Reef

    Science.gov (United States)

    Brenner, L. D.; Linsley, B. K.; Potts, D. C.

    2014-12-01

    Most coral-based paleoceanographic studies have used massive colonies of Porites or Faviidae, due to their long, continuously accreted skeletal records and sub-annual resolution, but other sub-massive corals provide an untapped resource. The genus Isopora is a dominant reef builder in some high-energy environments in the tropical western Pacific, and was a major component of cores recovered on IODP Leg 325 off the Great Barrier Reef (GBR). Despite its abundance, Isopora remains largely unexplored and hence underutilized in paleoceanographic studies. We present a modern Sr/Ca-δ18O-Sea Surface Temperature (SST) calibration of modern Isopora corals (n=3) collected from inner and outer reef locations ranging from 1-13m depth by Heron Island in the southern GBR in 2012. Pairing the Isopora Sr/Ca record with monthly SST yielded an average relationship of SST=-11.48×(Sr/Ca)+131.1 (r2 = 0.42-0.78). The Sr/Ca sensitivity of -0.087 mmol/mol/°C is similar to the sensitivity for Porites that was corrected for tissue layer smoothing effects determined by Gagan et al. (2012). The similarity between our Sr/Ca-SST sensitivity and the corrected sensitivity for Porites suggests tissue layer effects are minimal in Isopora. The mean annual SST amplitude recorded by the corals from 2008-2011 (full annual cycles) was 5.3°C and the average δ18O annual cycle of 1.1‰ approximates that expected if salinity had little effect on coral δ18O, assuming a previously established conversion of -0.23‰ (δ18O)/°C for biogenic aragonite. The average annual salinity amplitude of 0.3 in gridded data from around Heron Island supports our conclusion that δ18O variability is forced almost completely by SST. This modern Sr/Ca-SST calibration will expand the paleoceanographic utility of Isopora and, by assisting interpretation of Sr/Ca data from fossil corals collected during IODP 325, will better constrain the timing and magnitude of sea level changes and surface conditions since the Last

  8. Isotopic variations ({delta}{sup 13} C and {delta}{sup 18} O) in Siderastrea stellata (Cnidaria-Anthozoa), Itamaraca island, State of Pernambuco, Northeastern Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Valderez P.; Sial, Alcides N. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Geologia. Lab. de Isotopos Estaveis; Mayeal, Elga M.; Exner, Marco Antonio [Pernambuco Univ., Recife, PE (Brazil). Dept. de Zoologia. Lab. de Macro e Megabentos

    1998-12-01

    Isotopic determinations for O and C were performed in coral skeletons collected in beach rocks from two localities (Orange and Catuama), Itamaraca Island, north littoral of the State of pernambuco, northeastern Brazil. Large variations of {delta}{sup 18} O and {delta}{sup 13} C in corals from both localities are found, the largest ones being observed at the Orange locality {delta}{sup 13} C in this locality varies from -0.8 to +1.8% PDB and {delta}{sup 1.8} O from -5.3 to -1.8% PDB, while at the Catuama locality, they vary from -1.8 to 0.1% PDB and -3.8 to -2.7% PDB, respectively. Large variations in {delta}{sup 18} O (up to 2.5%) coupled with weakly defined positive correlation between {delta}{sup 18} O and {delta}{sup 13} C, can be attributed to temperature variations as consequence of climatic perturbations. Temperature estimates, calculated from {delta}{sup 18} O values, assuming isotopic equilibrium with seawater, yield values between 24.9 deg C and 43.1 deg C at Orange, and from 28.4 deg C to 35 deg C at Catuama, all of them (expect one growth band from one sample) are high enough for the full development of the coral colony. Temperature average is 31.4 deg C at Orange, which is a little bit higher than that at Catuama, but both of them indicate thermal stress conditions. In all analyzed specimens, expect for one, at Orange, T increases was accompanied by decreasing in the organic activity, as suggested by corresponding negative {delta}{sup 13} C anomaly. Therefore, the observed bleaching is possibly related to thermal stress and the high T may be related to the El Nino-Southern Oscillation (ENSO) warning event. On the other hand, anthropogenic action at Orange, local of intense tourism throughout the year, coupled with high rate of sedimentation in the region, may contribute to the observed coral bleaching. (author)

  9. Oxygen isotope ratios (18O/16O) of hemicellulose-derived sugar biomarkers in plants, soils and sediments as paleoclimate proxy II: Insight from a climate transect study

    Science.gov (United States)

    Tuthorn, Mario; Zech, Michael; Ruppenthal, Marc; Oelmann, Yvonne; Kahmen, Ansgar; Valle, Héctor Francisco del; Wilcke, Wolfgang; Glaser, Bruno

    2014-02-01

    The oxygen isotopic composition of precipitation (δ18Oprec) is well known to be a valuable (paleo-)climate proxy. Paleosols and sediments and hemicelluloses therein have the potential to serve as archives recording the isotopic composition of paleoprecipitation. In a companion paper (Zech et al., 2014) we investigated δ18Ohemicellulose values of plants grown under different climatic conditions in a climate chamber experiment. Here we present results of compound-specific δ18O analyses of arabinose, fucose and xylose extracted from modern topsoils (n = 56) along a large humid-arid climate transect in Argentina in order to answer the question whether hemicellulose biomarkers in soils reflect δ18Oprec. The results from the field replications indicate that the homogeneity of topsoils with regard to δ18Ohemicellulose is very high for most of the 20 sampling sites. Standard deviations for the field replications are 1.5‰, 2.2‰ and 1.7‰, for arabinose, fucose and xylose, respectively. Furthermore, all three hemicellulose biomarkers reveal systematic and similar trends along the climate gradient. However, the δ18Ohemicellulose values (mean of the three sugars) do not correlate positively with δ18Oprec (r = -0.54, p fucose and xylose do not simply reflect δ18Oprec but rather δ18Oleaf water. The correlation between measured δ18Ohemicellulose and modeled δ18Oleaf water is highly significant (r = 0.81, p < 0.001, n = 20). This finding can be attributed to the evaporative 18O enrichment of leaf water during transpiration. Model sensitivity tests using a Péclet-modified Craig-Gordon (PMCG) model corroborate that relative air humidity is a very rigorous climate parameter influencing δ18Oleaf water, whereas temperature is of minor importance. While oxygen exchange and degradation effects on δ18O values of hemicelluloses sugar biomarkers seem to be negligible (Zech et al., 2012), further effects that need to be considered when interpreting δ18Ohemicellulose

  10. Toward the Inference of Deglacial Ocean Dynamics from the Spatial Pattern of LGM-to-Modern d13C and d18O Change

    Science.gov (United States)

    Gebbie, G.; Peterson, C. D.; Lisiecki, L. E.; Spero, H. J.

    2014-12-01

    Estimates of the whole-ocean d13C change between the Last Glacial Maximum (LGM) and the modern-day are converging to values of about 0.4 per mil, and are of great use in partitioning land versus ocean contributions to the deglacial carbon cycle. To determine which specific oceanic processes are at play, however, knowledge of the spatial pattern of LGM-to-modern d13C and d18O change is critical. Spatial maps have mostly focused on Atlantic d13C, with less progress for d18O and the Pacific and Indian sectors, due to the concentration of sediment-core observations in the Atlantic and the difficulty in making meaningful maps from sparse data. Here, we demonstrate that a state estimation (or data assimilation) method based on recently compiled data and a simple kinematic ocean model simultaneously produces reasonable results for: 1) global maps of d13C and d18O, 2) uncertainty in the estimated properties, and 3) oceanic water-mass geometry. The observations include benthic d13C and d18O data from 493 marine sediment cores that were collected from the scientific literature and NOAA, PANGEA, and Delphi databases. The kinematic model permits each data point to have influence both up- and downstream along a water-mass pathway, typically allowing a larger geographical range than a statistical interpolation method. No assumption regarding the state of the circulation is necessary, and the modern-day circulation need not be assumed to be representative of the LGM. With this method, meridional (or other) sections can be compared between ocean basins. Furthermore, the internally-consistent d18O and d13C maps are used to determine the LGM-to-modern spatial changes that are robust given the uncertainty and sparsity of data. Rather than simply focus on property maps, we suggest that the link between observations and circulation changes (as reflected by the paths that water travels), points the way toward dynamical processes that must be explained. A particular application of our

  11. Constraining the origin of the Messinian gypsum deposits using coupled measurement of δ^{18}O$/δD in gypsum hydration water and salinity of fluid inclusions

    Science.gov (United States)

    Evans, Nicholas P.; Gázquez, Fernando; McKenzie, Judith A.; Chapman, Hazel J.; Hodell, David A.

    2016-04-01

    We used oxygen and hydrogen isotopes of gypsum hydration water (GHW) coupled with salinity deduced from ice melting temperatures of primary fluid inclusions in the same samples (in tandem with 87Sr/86Sr, δ34S and other isotopic measurements) to determine the composition of the mother fluids that formed the gypsum deposits of the Messinian Salinity Crisis from shallow and intermediate-depth basins. Using this method, we constrain the origin of the Messinian Primary Lower Gypsum (PLG) of the Sorbas basin (Betic foreland) and both the Upper Gypsum (UG) and the Lower Gypsum of the Sicilian basin. We then compare these results to measurements made on UG recovered from the deep Ionian and Balearic basins drilled during DSDP Leg 42A. The evolution of GHW δ18O/δD vs. salinity is controlled by mixing processes between fresh and seawater, coupled with the degree of evaporation. Evaporation and subsequent precipitation of gypsum from fluids dominated by freshwater will result in a depressed 87Sr/86Sr values and different trajectory in δ18O/δD vs. salinity space compared to fluids dominated by seawater. The slopes of these regression equations help to define the end-members from which the fluid originated. For example, salinity estimates from PLG cycle 6 in the Sorbas basin range from 18 to 51ppt, and after correction for fractionation factors, estimated δ18O and δD values of the mother water are low (-2.6 salinity) are within error of the average isotope composition of the modern precipitation and groundwater in this region of SE Spain. This indicates there was a significant contribution of meteoric water during gypsum deposition, while 87Sr/86Sr (0.708942 salinities of fluid inclusions are higher averaging ˜100ppt. In contrast to cycle 6, the intercepts of the regression equations of cycle 2 display more positive δ18O/δD values. While the estimated range in δ18O and δD of the mother water and salinities fall below those expected from the evaporation of seawater

  12. The δ15N and δ18O values of N2O produced during the co-oxidation of ammonia by methanotrophic bacteria

    Science.gov (United States)

    Mandernack, Kevin W.; Mills, Christopher T.; Johnson, Craig A.; Rahn, Thomas; Kinney, Chad

    2009-01-01

    In order to determine if the δ15N and δ18O values of N2O produced during co-oxidation of NH4+ by methanotrophic (methane oxidizing) bacteria can be isotopically distinguished from N2O produced either by autotrophic nitrifying or denitrifying bacteria, we conducted laboratory incubation experiments with pure cultures of methanotrophic bacteria that were provided NH4Cl as an oxidation substrate. The N2O produced during NH4+ oxidation by methanotrophic bacteria showed nitrogen isotope fractionation between NH4+ and N2O (εN2O–NH4+) of − 48 and − 55‰ for Methylomonas methanica and Methylosinus trichosporium, OB3b respectively. These large fractionations are similar to those previously measured for autotrophic nitrifying bacteria and consistent with N2O formation by multiple rate limiting steps that include NH4+oxidation by the methane monooxygenase enzyme and reduction of NO2− to N2O. Consequently, N2O formed by NH4+ oxidation via methanotrophic or autotrophic nitrifying bacteria might generally be characterized by lower δ15NN2O values than that formed by denitrificaiton, although this also depends on the variability of δ15N of available nitrogen sources (e.g., NH4+, NO3−, NO2−). Additional incubations with M. trichosporium OB3b at high and low CH4 conditions in waters of different δ18O values revealed that 19–27% of the oxygen in N2O was derived from O2 with the remainder from water. The biochemical mechanisms that could explain this amount of O2 incorporation are discussed. The δ18O of N2O formed under high CH4 conditions was ~ + 15‰ more positive than that formed under lower CH4 conditions. This enrichment resulted in part from the incorporation of O2 into N2O that was enriched in 18O due to an isotope fractionation effect of − 16.1 ± 2.0‰ and − 17.5 ± 5.4‰ associated with O2 consumption during the high and low methane concentration incubations, respectively. Therefore, N2O formed by NH4+

  13. Climatic fluctuations and seasonality during the Late Jurassic (Oxfordian-Early Kimmeridgian) inferred from δ18O of Paris Basin oyster shells

    Science.gov (United States)

    Brigaud, Benjamin; Pucéat, Emmanuelle; Pellenard, Pierre; Vincent, Benoît; Joachimski, Michael M.

    2008-08-01

    Oxygen isotope data from biostratigraphically well-dated oyster shells from the Late Jurassic of the eastern Paris Basin are used to reconstruct the thermal evolution of western Tethyan surface waters during the Early Oxfordian-Early Kimmeridgian interval. Seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy. Isotope analyses were performed on non-luminescent parts of shells (n = 264). Intra-shell δ18O variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell. The sinusoidal distribution of the δ18O values along this transect and the dependence of the amplitude of variations with bathymetry suggest that intra-shell variability reflects seasonal variations of temperature and/or salinity. Average amplitudes of about 5 °C in shallow water environments and of about 2-3 °C in deeper offshore environments are calculated. These amplitudes reflect minimum seasonal temperature variation. Our new data allow to constrain existing paleotemperature trends established from fish tooth and belemnite δ18O data and are in better agreement with paleontological data. More specifically, a warming trend of about 3 °C is reconstructed for oceanic surface waters during the Early to Middle Oxfordian transition, with maximum temperatures reaching 24 °C in the transversarium Zone (late Middle Oxfordian). From the transversarium Zone to the bimmamatum Zone, a cooling of about 7 °C is indicated, whereas from the bimmamatum Zone, temperatures increased again by about 7 °C to reach 24 °C in average during the cymodoce Zone (Early Kimmeridgian).

  14. Study of leachate contamination in Bantar Gebang landfill to its shallow groundwater using natural isotope tracers of 18O, 2H and 3H

    International Nuclear Information System (INIS)

    Leaching from Bantar Gebang landfill, Jakarta’s main municipal landfill, especially from its two waste water treatment plants (plant A in zone-3 and plant B in Sumur Batu) to underlying aquifer has been studied using isotope techniques. The study was based on the abundances of the heavier isotopes in water molecules namely 18O, 2H (deuterium) and 3H (tritium). Because both water in the waste-water treatment plants and groundwater have undergone different independent physical processes, it was assumed that each water source has its own typical finger-print in term of the abundances of 18O, 2H (deuterium) and 3H (tritium). Leachate from the two waste water treatment plants have higher 2H, 3H activities, and physical parameters (EC, TDS, and pH) values than those of groundwater samples. Because of the age and size of the two waste water treatment plants are significantly different, it was also observed that the isotope contents of plant B, younger age and smaller size, was relatively lower in 2H values and 3H activities compared to those of plant A. These phenomena have been used to identify the leaching from waste-water treatment plants of Bantar Gebang landfill to the underlying aquifer. During the dry season, it was observed that 2H values in leachate were generally higher than those in rainy season. This result might be due to the extensive methane production in the treatment plants. Conversely, 18O-shifting in leachate from local meteoric line indicated that the leachate had experienced evaporation. Buried luminescent paints in the landfill were most likely the source of high tritium activity in leachate. Based on the samples collected from the study area (mostly from dug or bore wells), it was found that the underlying aquifer especially shallow groundwater has been contaminated up to as high as 33% with leachate. (author)

  15. Multipolarity analysis for {sup 14}C high-energy resonance populated by ({sup 18}O,{sup 16}O) two-neutron transfer reaction

    Energy Technology Data Exchange (ETDEWEB)

    Carbone, D., E-mail: carboned@lns.infn.it; Cavallaro, M.; Bondì, M.; Agodi, C.; Cunsolo, A. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Cappuzzello, F. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Azaiez, F.; Franchoo, S.; Khan, E. [Institut de Physique Nucleaire, Universitè Paris-Sud, Orsay (France); Bonaccorso, A. [INFN-Sezione di Pisa, Pisa (Italy); Fortunato, L. [Dipartimento di Fisica e Astronomia, Università di Padova, Padova (Italy); INFN-Sezione di Padova, Padova (Italy); Foti, A. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); INFN-Sezione di Catania, Catania (Italy); Linares, R.; Lubian, J. [Instituto de Fisica, Universidade Federal Fluminense, Niteroi (Brazil); Scarpaci, J. A. [Centre de Sciences Nucleaires et de Sciences de Matieres, Universitè Paris-Sud, Orsay (France); Vitturi, A. [INFN-Sezione di Padova, Padova (Italy); INFN-Sezione di Catania, Catania (Italy)

    2015-10-15

    The {sup 12}C({sup 18}O,{sup 16}O){sup 14}C reaction at 84 MeV incident energy has been explored up to high excitation energy of the residual nucleus thanks to the use of the MAGNEX spectrometer to detect the ejectiles. In the region above the two-neutron separation energy, a resonance has been observed at 16.9 MeV. A multipolarity analysis of the cross section angular distribution indicates an L = 0 character for such a transition.

  16. Extracting the cross section angular distributions for 15C high-energy resonance excited via the (18O,16O two-neutron transfer reaction

    Directory of Open Access Journals (Sweden)

    Carbone D.

    2016-01-01

    Full Text Available The 13C(18O,16O15C reaction has been studied at 84 MeV incident energy. The ejectiles have been momentum analized by the MAGNEX spectrometer and 15C excitation energy spectra have been obtained up to about 20 MeV. In the region above the two-neutron separation energy, a bump has been observed at 13.7 MeV. The extracted cross section angular distribution for this structure, obtained by using different models for background, displays a clear oscillating pattern, typical of resonant state of the residual nucleus.

  17. Quantum dynamics of {sup 16}O + {sup 36}O{sub 2} and {sup 18}O + {sup 32}O{sub 2} exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    Rajagopala Rao, T.; Mahapatra, S., E-mail: smsc@uohyd.ernet.in [School of Chemistry, University of Hyderabad, Hyderabad 500 046 (India); Guillon, G. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, CNRS-Université de Bourgogne, 21078 Dijon Cedex (France); Honvault, P., E-mail: pascal.honvault@univ-fcomte.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, CNRS-Université de Bourgogne, 21078 Dijon Cedex (France); UFR Sciences et Techniques, Université de Franche-Comté, 25030 Besançon Cedex (France)

    2015-05-07

    We present quantum dynamical investigations of {sup 16}O + {sup 36}O{sub 2} and {sup 18}O + {sup 32}O{sub 2} exchange reactions using a time-independent quantum mechanical method and an accurate global potential energy surface of ozone [Dawes et al., J. Chem. Phys. 135, 081102 (2011)]. Initial state-selected integral cross sections, rate constants, and Boltzmann averaged thermal rate constants are obtained and compared with earlier experimental and theoretical results. The computed thermal rate constants for the oxygen exchange reactions exhibit a negative temperature dependence, as found experimentally. They are in better agreement with the experiments than the previous studies on the same reactions.

  18. Identifying residence times and streamflow generation processes using δ18O and δ2H in meso-scale catchments in the Abay/Upper Blue Nile, Ethiopia

    OpenAIRE

    Teklaeb, S.; Wenninger, J.W.; Uhlenbrook, S.

    2013-01-01

    Measurements of the stable isotopes oxygen-18 (18O) and deuterium (2H) were carried out in two meso-scale catchments, Chemoga (358 km2) and Jedeb (296 km2) south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin. Stable isotope composition in precipitation, spring water and streamflow were analyzed (i) to characterize the spatial and temporal variations of water fluxes; (ii) to estimate the mean residence time o...

  19. Particle–particle Tamm–Dancoff approximation and particle–particle random phase approximation calculations for 18O and 18F nuclei

    Indian Academy of Sciences (India)

    Alih Taqi Al-Bayati

    2013-02-01

    The nuclear structures of 18O and 18F nuclei are studied using particle–particle Tamm–Dancoff approximation (pp TDA) and particle–particle random phase approximation (pp RPA). All possible single-particle states of the allowed angular momenta are considered in the 0p and 1s–0d shells. The Hamiltonian is diagonalized in the presence of Warburton and Brown interactions. The results containing energy-level schemes and transition strength (2) are compared with the available experimental data.

  20. New High-Precision Measurement of the Reaction Rate of the 18O(p,alpha)15N Reaction via THM

    CERN Document Server

    La Cognata, M; Mukhamedzhanov, A M; Irgaziev, B; Tribble, R E; Banu, A; Cherubini, S; Coc, A; Crucilla, V; Goldberg, V Z; Gulino, M; Kiss, G G; Lamia, L; Chengbo, L; Mrazek, J; Pizzone, R G; Puglia, S M R; Rapisarda, G G; Romano, S; Sergi, M L; Tabacaru, G; Trache, L; Trzaska, W; Tumino, A

    2009-01-01

    The 18O(p,alpha)15N reaction rate has been extracted by means of the Trojan-Horse method. For the first time the contribution of the 20-keV peak has been directly evaluated, giving a value about 35% larger than previously estimated. The present approach has allowed to improve the accuracy of a factor 8.5, as it is based on the measured strength instead of educated guesses or spectroscopic measurements. The contribution of the 90-keV resonance has been determined as well, which turned out to be of negligible importance to astrophysics.

  1. Synthesis of LiMn2O4 and LiCr0.2Mn1.8O4 powders by modified Pechini process

    Directory of Open Access Journals (Sweden)

    Alexandre Urbano

    2009-03-01

    Full Text Available LiMn2O4 and LiCr0.2Mn1.8O4 powders were synthesized by Pechini process, modified in order to reduce the number of steps and to work at temperatures below or equal to 400oC. Both phases crystallize in the same spinel structure with lattice constants of 8.21 and 8.22 Å respectively. Although the annealing temperature was low, the cristallinity is good and no residual amounts of organic material were detected.

  2. Anomalous flow below 2700 m in the EPICA Dome C ice core detected using δ18O of atmospheric oxygen measurements

    Directory of Open Access Journals (Sweden)

    M. Leuenberger

    2007-06-01

    Full Text Available While there are no indications of mixing back to 800 000 years in the EPICA Dome C ice core record, comparison with marine sediment records shows significant differences in the timing and duration of events prior to stage 11 (~430 ka, thousands of years before 1950. A relationship between the isotopic composition of atmospheric oxygen (δ18O of O2, noted δ18Oatm and daily northern hemisphere summer insolation has been observed for the youngest four climate cycles. Here we use this relationship with new δ18O of O2 measurements to show that anomalous flow in the bottom 500 m of the core distorts the duration of events by up to a factor of 2. By tuning δ18Oatm to orbital precession we derive a corrected thinning function and present a revised age scale for the interval corresponding to Marine Isotope Stages 11–20 in the EPICA Dome C ice core. Uncertainty in the phasing of δ18Oatm with respect to insolation variations in the precession band limits the accuracy of this new agescale to ±6 kyr (thousand of years. The previously reported ~30 kyr duration of interglacial stage 11 is unchanged. In contrast, the duration of stage 15.1 is reduced by a factor of 2, from 31 to 16 kyr.

  3. Testing coral paleothermometers (B/Ca, Mg/Ca, Sr/Ca, U/Ca andδ18O) under impacts of large riverine runoff

    Institute of Scientific and Technical Information of China (English)

    CHEN Tianran; YU Kefu; ZHAO Jianxin; YAN Hongqiang; SONG Yinxian; FENG Yuexing; CHEN Tegu

    2015-01-01

    Sea surface temperature (SST) proxies including B/Ca, Mg/Ca, Sr/Ca, U/Ca andδ18O were analyzed in the skeleton of aPorites coral collected from the Zhujiang River (Pearl River) Estuary (ZRE). These geochemical proxies are influenced by river runoff and this area of the northern South China Sea is strongly affected by seasonal freshwater floods. We assessed the robustness of each SST proxy through comparison with the local instrumental SST. Coral Sr/Ca shows the highest correlation with SST variations (r2=0.59), suggesting Sr/Ca is the most robust SST proxy. In contrast, coralδ18O (r2=0.46), B/Ca (r2=0.43) and U/Ca (r2=0.41) ratios were only moderately correlated with SST variations, suggesting that they are disturbed by some other factors in addition to SST. The poor correlation (r2=0.27) between SST and Mg/Ca indicates that Mg/Ca in coral skeletons is not a simple function of SST variations. This may ultimately limit the use of Mg/Ca as a coral paleothermometer.

  4. Anomalous flow below 2700 m in the EPICA Dome C ice core detected using δ18O of atmospheric oxygen measurements

    Directory of Open Access Journals (Sweden)

    A. Tisserand

    2007-01-01

    Full Text Available While there are no indications of mixing back to 800 000 years in the EPICA Dome C ice core record, comparison with marine sediment records shows significant differences in the timing and duration of events prior to stage 11 (~430 ka, thousand of years before 1950. A relationship between the isotopic composition of atmospheric oxygen (δ18O of O2, noted δ18Oatm and daily northern hemisphere summer insolation has been observed for the youngest four climate cycles. Here we use this relationship with new δ18O of O2 measurements to show that anomalous flow in the bottom 500 m of the core distorts the duration of events by up to a factor of 2. By tuning δ18Oatm to orbital precession we derive a corrected thinning function and present a revised age scale for the interval corresponding to Marine Isotope Stages 11–20 in the EPICA Dome C ice core. Uncertainty in the phasing of δ18Oatm with respect to insolation variations in the precession band limits the accuracy of this new agescale to ±6 kyr (thousand of years. The previously reported ~30 kyr duration of interglacial stage 11 is unchanged. In contrast, the duration of stage 15.1 is reduced by a factor of 2, from 31 to 16 kyr.

  5. Increasing aridity threats to Himalayan alpine ecosystems? A millenial history of hydroclimate from the Tibetan plateau derived from a δ18O tree-ring network

    Science.gov (United States)

    Griessinger, J.

    2015-12-01

    The Tibetan plateau (TP) plays an important role as an elevated heat source responsible for the establishment of the Asias monsoonal systems. Besides the Indian Summer Monsoon (ISM), also the East Asian Summer Monsoon (EASM) is triggering the regional precipitation regimes during the vegetation period from May to September. Within recent decades, fundamental climate changes on the southeastern part of the TP were detected leading to substantial changes within the regional hydrological budget and affecting local ecosystems. By using a spatial network of multicentennial to 1.5 millenial year old tree-ring δ18O time-series from the southeastern part of the TP, the regional climate history as well as the late Holocene monsoonal variability will be presented. Since the main climatically sensitive periods like the Medieval Warm Period and the Little Ice Age are displayed in all chronologies, their typical hydroclimatological characteristics and impacts will be discussed especially in regard to the recent warming trend on the TP and the responsible climatic triggers. Arising from these results, regional impacts and differences of the proposed hydrological changes will be discussed. In addition, first results of a comparison between proxy-based (δ18O) and model-based (re-analysis datasets) trajectory calculations will be presented, trying to give insights in the origin and impact of air masses for the most striking last three decades on the southeastern part of the TP.

  6. Use of Isotope Ratio Mass Spectrometry (IRMS) Determination ((18)O/(16)O) to Assess the Local Origin of Fish and Asparagus in Western Switzerland.

    Science.gov (United States)

    Rossier, Joël S; Maury, Valérie; de Voogd, Blaise; Pfammatter, Elmar

    2014-10-01

    Here we present the use of isotope ratio mass spectrometry (IRMS) for the detection of mislabelling of food produced in Switzerland. The system is based on the analysis of the oxygen isotope distribution in water (δ(18)O). Depending on the location on the earth, lake or groundwater has a specific isotopic distribution, which can serve as a fingerprint in order to verify whether a product has grown by means of the corresponding water. This report presents specifically the IRMS technique and the results obtained in the origin detection of fish grown in selected Swiss lakes as well as asparagus grown in Valais ground. Strengths and limitations of the method are presented for both cited products; on one hand, the technique is relatively universal for any product which contains significant water but on the other hand, it necessitates a rather heavy workload to build up a database of water δ(18)O values of products of different origins. This analytical tool is part of the concept of combating fraud currently in use in Switzerland. PMID:25437160

  7. Gas emissions in Planck cold dust clumps---A Survey of the J=1-0 Transitions of $^{12}$CO, $^{13}$CO, and C$^{18}$O

    CERN Document Server

    Wu, Yuefang; Meng, Fanyi; Li, Di; Qin, Sheng-Li; Ju, Bing-Gang

    2012-01-01

    A survey toward 674 Planck cold clumps of the Early Cold Core Catalogue (ECC) in the J=1-0 transitions of $^{12}$CO, $^{13}$CO and C$^{18}$O has been carried out using the PMO 13.7 m telescope. 673 clumps were detected with the $^{12}$CO and $^{13}$CO, and 68% of the samples have C$^{18}$O emission. Additional velocity components were also identified.A close consistency of the three line peak velocities was revealed for the first time. Kinematic distances are given out for all the velocity components and half of the clumps are located within 0.5 and 1.5 kpc. Excitation temperatures range from 4 to 27 K, slightly larger than those of $T_d$. Line width analysis shows that the majority of ECC clumps are low mass clumps. Column densities N$_{H_{2}}$ span from 10$^{20}$ to 4.5$\\times10^{22}$ cm$^{-2}$ with an average value of (4.4$\\pm$3.6)$\\times10^{21}$ cm$^{-2}$. N$_{H_{2}}$ cumulative fraction distribution deviates from the lognormal distribution, which is attributed to optical depth. The average abundance rati...

  8. Variability of {sup 10}Be and {delta}{sup 18}O in snow pits from Greenland and a surface traverse from Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Berggren, A.-M. [Dept. of Earth Sciences, Uppsala University, Villav. 16, 752 36 Uppsala (Sweden); Aldahan, A., E-mail: ala.aldahan@geo.uu.se [Dept. of Earth Sciences, Uppsala University, Villav. 16, 752 36 Uppsala (Sweden); Dept. of Geology, United Arab Emirates University, P.O. Box 17551 Al Ain (United Arab Emirates); Possnert, G. [Tandem Laboratory, Uppsala University, P.O. Box 529, 751 20 Uppsala (Sweden); Hansson, M. [Dept. of Physical Geography and Quaternary Geology, Stockholm University, 106 91 Stockholm (Sweden); Steen-Larsen, H.C. [Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej, 30,2100 Copenhagen (Denmark); Sturevik Storm, A. [Dept. of Earth Sciences, Uppsala University, Villav. 16, 752 36 Uppsala (Sweden); Moerth, C.-M. [Dept. of Geology and Geochemistry, Stockholm University, 106 91 Stockholm (Sweden); Murad, A. [Dept. of Geology, United Arab Emirates University, P.O. Box 17551 Al Ain (United Arab Emirates)

    2013-01-15

    To examine temporal variability of {sup 10}Be in glacial ice, we sampled snow to a depth of 160 cm at the NEEM (North Greenland Eemian Ice Drilling) drilling site in Greenland. The samples span three years between the summers of 2006 and 2009. At the same time, spatial variability of {sup 10}Be in glacial ice was explored through collection of the upper {approx}5 cm of surface snow in Antarctica during part of the Swedish-Japanese traverse from Svea to Syowa station during the austral summer in 2007-2008. The results of the Greenlandic {sup 10}Be snow suggested variable concentrations that apparently do not clearly reflect the seasonal change as indicated by the {delta}{sup 18}O data. The {sup 10}Be concentration variability most likely reflects also effects of aerosol loading and deposition pathways, possibly in combination with post-depositional processes. The Antarctic traverse data expose a negative correlation between {sup 10}Be and {delta}{sup 18}O, while there are weaker but still significant correlations to altitude and distance to the coast (approximated by the distance to the 70th latitude). These relationships indicate that geographical factors, mainly the proximity to the coast, may strongly affect {sup 10}Be concentrations in snow in Queen Maud Land, Antarctica.

  9. 18O /16O and 13C /12C in lower Paleozoic articulate brachiopods: Implications for the isotopic composition of seawater

    Science.gov (United States)

    Wadleigh, Moire A.; Veizer, Ján

    1992-01-01

    Three hundred and eleven articulate brachiopods, with extensive geographic coverage, spanning the Cambrian to Silurian stratigraphic interval, were analyzed for oxygen and carbon isotopic composition. Cambrian samples have δ18O ≤ -7%., Ordovician samples ≤ -2.4‰, and Silurian samples ≤ -1.9‰, confirming the previously established trend towards lighter isotopic compositions with increasing age throughout the Lower Paleozoic. Forty-nine "best preserved" Ordovician and Silurian samples were identified based on scanning electron microscopy and trace element analysis. They were found to bracket the isotopic compositions of over 85% of specimens from these stratigraphic intervals supporting widespread preservation of the isotopic signal. Some latest Ordovician and Lower Ludlovian samples associated with shale sequences are apparently "enriched" in 18O. These are interpreted as an environmental phenomenon, perhaps related to water temperature and glaciation. A number of Silurian samples of varying genera and stratigraphic levels are highly enriched in 13C, up to +6‰. Some are shale related, but some are associated with carbonate-bearing basins. These are also thought to represent "near-original" compositions, but a single environmental cause is unknown. The present data show that luminescence is not a decisive criterion for evaluating the degree of brachiopod preservation. Whole-shell values were isotopically similar to their nonluminescent portions for both oxygen and carbon.

  10. Estimating the regional climate signal in a late Pleistocene and early Holocene lake-sediment δ18O record from Vermont, USA.

    Science.gov (United States)

    Mandl, Maximilian Benedict; Shuman, Bryan Nolan; Marsicek, Jeremiah; Grigg, Laurie

    2016-07-01

    We present a new oxygen isotope (δ18O) record from carbonate-rich lake sediments from central Vermont. The record from Twin Ponds spans from 13.5 cal ka BP (1950 AD) to present, but contains a 6 ka long hiatus starting shortly after 7.5 cal ka BP. We compare the record for ca. 13.5-7.5 cal ka BP with published δ18O data from the region after using a Bayesian approach to produce many possible chronologies for each site. Principal component analysis then identified chronologically-robust, multi-site oxygen isotope signals, including negative values during the Younger Dryas, but no significant deviations from the early Holocene mean of the regional records. However, differences among sites indicate significant trends that likely relate to interacting changes in the regional gradients of seasonal temperatures and precipitation as well as moisture sources, moisture pathways, and aridity that were controlled by large-scale climatic controls such as insolation, the progressive decline of the Laurentide Ice Sheet, and changes in oceanic circulation. Centennial shifts punctuate these trends at ca. 9.3 and 8.2 cal ka BP, and reveal that the local character of these short-lived features requires a detailed understanding of lake hydrology and regional isotopic gradients to yield reliable information for regional climate reconstructions.

  11. Precipitation origin and evaporation of lakes in semi-arid Patagonia (Argentina) inferred from stable isotopes ( δ18O, δ2H)

    Science.gov (United States)

    Mayr, Christoph; Lücke, Andreas; Stichler, Willibald; Trimborn, Peter; Ercolano, Bettina; Oliva, Gabriel; Ohlendorf, Christian; Soto, Julio; Fey, Michael; Haberzettl, Torsten; Janssen, Stephanie; Schäbitz, Frank; Schleser, Gerhard H.; Wille, Michael; Zolitschka, Bernd

    2007-02-01

    Stable isotope approaches are often used for estimating water balances of lakes. Such studies require regional background information about hydrogen and oxygen isotope variability of lakes and their potential inflows. Here, a stable isotope database ( δ2H and δ18O) is presented for estimating evaporation to inflow ratios ( E/ I) of lakes in semi-arid southern Patagonia. Water samples of 23 lakes and ponds located in the Patagonian steppe at about 52°S were sampled during three subsequent austral summers. Two deep crater lakes, Laguna Azul and Laguna Potrok Aike, were studied in more detail during a two-years monitoring. Furthermore, precipitation, groundwater and atmospheric water vapor were sampled for isotope analyses. Presented data imply that the isotopic composition of rainfall in southeastern Patagonia is predominantly determined by precipitation amount and moisture source area. For the investigated area, the first meteoric water and evaporation lines in δ2H vs. δ18O space are presented. The database was further used to estimate the water balances of the two crater lakes, Laguna Azul and Laguna Potrok Aike, which are in the focus of recent paleoclimatic investigations. According to that approach about 50% and 60%, respectively, of the water entering Laguna Azul and Laguna Potrok Aike via surface and subsurface inflow evaporates. These results testify a considerable flow of lake waters into the groundwater.

  12. Chemical weathering and the role of sulfuric and nitric acids in carbonate weathering: Isotopes (13C, 15N, 34S, and 18O) and chemical constraints

    Science.gov (United States)

    Li, Cai; Ji, Hongbing

    2016-05-01

    Multiple isotopes (13C-DIC, 34S and 18O-SO42-, 15N and 18O-NO3-) and water chemistry were used to evaluate weathering rates and associated CO2 consumption by carbonic acid and strong acids (H2SO4 and HNO3) in a typical karst watershed (Wujiang River, Southwest China). The dual sulfate isotopes indicate that sulfate is mainly derived from sulfide oxidation in coal stratum and sulfide-containing minerals, and dual nitrate isotopes indicate that nitrate is mainly derived from soil N and nitrification. The correlation between isotopic compositions and water chemistry suggests that sulfuric and nitric acids, in addition to carbonic acid, are involved in carbonate weathering. The silicate and carbonate weathering rates are 7.2 t km-2 yr-1 and 76 t km-2 yr-1, respectively. In comparison with carbonate weathering rates (43 t km-2 yr-1) by carbonic acid alone, the subsequent increase in rates indicates significant enhancement of weathering when combined with sulfuric and nitric acids. Therefore, the role of sulfuric and nitric acids in the rock weathering should be considered in the global carbon cycle.

  13. A megasplice of globally distributed benthic δ18O records exposes the different astronomical rhythms of the last 35 million years.

    Science.gov (United States)

    De Vleeschouwer, David; Vahlenkamp, Maximilian; Crucifix, Michel; Pälike, Heiko

    2016-04-01

    Compilations of worldwide benthic δ18O records (e.g. Cramer et al., 2009; Zachos et al., 2001; Zachos et al., 2008) led to a significant improvement of our understanding of changing ocean circulation characteristics in the Cenozoic. However, in these compilations, different isotopic records are accumulated and individual astronomical cycles are not always clearly recognizable. Here, we present a benthic δ18O megasplice for the last 35 Ma that results from the splicing of a dozen globally distributed high-resolution isotope records (>11000 measurements). We carefully correlated these isotope records in their overlapping parts, and slightly revised the original astronomical age models where necessary. The result is a megasplice in which individual astronomical cycles are clearly delineated throughout the last 35 Ma. Benthic δ18O records from the deep ocean can be regarded as resembling globally averaged temperature and ice-volume conditions. Nevertheless, an important disadvantage of the megasplice consists of the fact that data from single sites do not reflect whole ocean conditions. We account for possible local effects by presenting different versions of the megasplice, each version consisting of a different combination of records. Subsequently, the imprint of astronomical climate forcing in the megasplice is displayed in a novel way. We display the response of benthic δ18O to obliquity and eccentricity-modulated precession for 800-kyr wide time-windows. The δ18O response in function of obliquity and e*sin(ω) allows for an assessment of the relative strength of obliquity and precession. A similar display in function of e*sin(ω) and e*cos(ω) should be read as a polar plot of which the azimuth represents the longitude of the perihelion and the distance from the pole represents eccentricity. The month during which the Earth reaches perihelion is indicated at the corresponding azimuth. This novel way of visualizing the astronomical imprint allows us to

  14. Preparation of Y2P2W18O62·nH2O/4A Zeolite and Its Application for Catalytic Synthesis of Acetylsalicylic Acid%Y2P2W18O62·nH2O/4A-分子筛的制备及催化合成乙酰水杨酸

    Institute of Scientific and Technical Information of China (English)

    曹小华

    2016-01-01

    以4A-分子筛为载体,Dawson结构磷钨酸钇(Y2P2W18O62·nH2O)为活性组分,采用浸渍法制备出负载型40%Y2P2W18 O62· nH2O/4A-分子筛,并通过FT IR、EDS、SEM、NH3-TPD及N2吸附-脱附等方法对催化剂进行表征.将其用于催化水杨酸和乙酸酐反应制备乙酰水杨酸,考察了各因素对反应的影响.结果表明,负载前后磷钨酸钇均保持Dawson结构,Y2P2W18O62·nH2O和40%Y2P2W18O62·nH2O/4A-分子筛均呈球形,负载后催化剂的比表面积增大,酸强度和酸量均明显提高.在优化反应条件(水杨酸与乙酸酐摩尔比为1∶3,反应时间为30min,催化剂用量为反应物质量分数的2.3%)下,乙酰水杨酸收率为95.2%.催化剂重复使用6次,乙酰水杨酸收率仍保持为77.9%.

  15. Effect of temperature on the oxygen isotope composition of carbon dioxide (δ18O) prepared from carbonate minerals by reaction with polyphosphoric acid: An example of the rhombohedral CaCO 3-MgCO 3 group minerals

    Science.gov (United States)

    Crowley, Stephen F.

    2010-11-01

    Measurement of the ratio of 18O to 16O in CO 2(δ18O) produced from rhombohedral carbonate minerals in the compositional range CaCO 3-MgCO 3 by reaction with polyphosphoric acid (PPA), at temperatures of between 25 and 110 °C, shows that values of δ18O are linearly correlated ( r o > 0.99) with the reciprocal of absolute reaction temperature (K/ T). This observation is consistent with earlier studies documenting the effect of temperature on the kinetic fractionation of oxygen isotopes between parent carbonate and product CO 2 and H 2O during acid decomposition. However, analysis of the resultant data reveals: (1) a progressive increase in dδ18O/dT-1 with increasing Mg content, and (2) a significant variation in dδ18O/dT-1 between individual samples of carbonate of identical lattice symmetry and similar chemical composition. The overall increase in gradient with increasing Mg content is assumed to reflect cation radius dependent factors that control the bonding environment at the interface between the metal cation exposed at the surface of the reacting carbonate solid and a H 2CO 3 transitional species during disproportionation of H 2CO 3 to CO 2 and H 2O ("cluster model" of Guo et al., 2009). Phase-specific variations in dδ18O/dT-1 might result from differences in lattice structure variables (e.g., degree of lattice distortion, extent of positional disorder, and non-ideal mixing of substituent cations where carbonates depart from end-member compositions). Lattice structure variables may be dependent on geochemical conditions pertaining at the time of carbonate precipitation (e.g., biosynthetic versus inorganic precipitates) and suggests that dδ18O/dT-1 has the potential to vary, within limits, in response to both the chemical composition and structure of each carbonate sample. Because the oxygen isotope composition of carbonate minerals (δ18O) measured on the VPDB scale is defined by the oxygen isotope composition of CO 2 prepared from NBS19 (calcite) by

  16. Fractionation of Oxygen Isotopes by Thermal Ionization Mass Spectrometry Inferred from Simultaneous Measurement of (17)O/(16)O and (18)O/(16)O Ratios and Implications for the (182)Hf-(182)W Systematics.

    Science.gov (United States)

    Trinquier, Anne

    2016-06-01

    Accurate (182)Hf-(182)W chronology of early planetary differentiation relies on highly precise and accurate tungsten isotope measurements. WO3(-) analysis by negative thermal ionization mass spectrometry requires W(17)O(16)O2(-), W(17)O2(16)O(-), W(18)O(16)O2(-), W(17)O3(-), W(17)O(18)O(16)O(-), and W(18)O2(16)O(-) isotopologue interference corrections on W(16)O3(-) species ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ; Touboul et al. Nature 2015 , 520 , 530 ; Touboul et al. Int. J. Mass Spectrom. 2012 , 309 , 109 ). In addition, low ion beam intensity counting statistics combined with Faraday cup detection noise limit the precision on the determination of (18)O/(16)O and (17)O/(16)O relative abundances. Mass dependent variability of (18)O/(16)O over the course of an analysis and between different analyses calls for oxide interference correction on a per integration basis, based on the in-run monitoring of the (18)O/(16)O ratio ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). Yet, the (17)O/(16)O variation is normally not being monitored and, instead, inferred from the measured (18)O/(16)O variation, assuming a δ(17)O-δ(18)O Terrestrial Fractionation Line ( Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). The purpose of the present study is to verify the validity of this assumption. Using high resistivity amplifiers, (238)U(17)O2 and (238)U(18)O2 ion beams down to 1.6 fA have been monitored simultaneously with (235,238)U(16)O2 species in a uranium certified reference material. This leads to a characterization of O isotope fractionation by thermal ionization mass spectrometry in variable loading and running conditions (additive-to-sample ratio, PO2 pressure, presence of ionized metal and oxide species). Proper determination of O

  17. Fractionation of Oxygen Isotopes by Thermal Ionization Mass Spectrometry Inferred from Simultaneous Measurement of (17)O/(16)O and (18)O/(16)O Ratios and Implications for the (182)Hf-(182)W Systematics.

    Science.gov (United States)

    Trinquier, Anne

    2016-06-01

    Accurate (182)Hf-(182)W chronology of early planetary differentiation relies on highly precise and accurate tungsten isotope measurements. WO3(-) analysis by negative thermal ionization mass spectrometry requires W(17)O(16)O2(-), W(17)O2(16)O(-), W(18)O(16)O2(-), W(17)O3(-), W(17)O(18)O(16)O(-), and W(18)O2(16)O(-) isotopologue interference corrections on W(16)O3(-) species ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ; Touboul et al. Nature 2015 , 520 , 530 ; Touboul et al. Int. J. Mass Spectrom. 2012 , 309 , 109 ). In addition, low ion beam intensity counting statistics combined with Faraday cup detection noise limit the precision on the determination of (18)O/(16)O and (17)O/(16)O relative abundances. Mass dependent variability of (18)O/(16)O over the course of an analysis and between different analyses calls for oxide interference correction on a per integration basis, based on the in-run monitoring of the (18)O/(16)O ratio ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). Yet, the (17)O/(16)O variation is normally not being monitored and, instead, inferred from the measured (18)O/(16)O variation, assuming a δ(17)O-δ(18)O Terrestrial Fractionation Line ( Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). The purpose of the present study is to verify the validity of this assumption. Using high resistivity amplifiers, (238)U(17)O2 and (238)U(18)O2 ion beams down to 1.6 fA have been monitored simultaneously with (235,238)U(16)O2 species in a uranium certified reference material. This leads to a characterization of O isotope fractionation by thermal ionization mass spectrometry in variable loading and running conditions (additive-to-sample ratio, PO2 pressure, presence of ionized metal and oxide species). Proper determination of O

  18. How well do we know VPDB? Variability of delta13C and delta18O in CO2 generated from NBS19-calcite.

    Science.gov (United States)

    Brand, Willi A; Huang, Lin; Mukai, Hitoshi; Chivulescu, Alina; Richter, Jürgen M; Rothe, Michael

    2009-03-01

    In order to generate a local daughter scale from the material defining the international delta13C and delta18O stable isotope ratio scales (NBS19-calcite),1,2 the carbon and oxygen must be liberated to the gas phase, usually as CO2, using acid digestion of the calcite with H3PO4. It is during this conversion step that systematic errors can occur, giving rise to commonly observed discrepancies in isotopic measurements between different stable isotope laboratories. Scale consistency is of particular importance for air-CO2 isotope records where very small differences in isotopic composition have to be reliably compared between different laboratories and quantified over long time periods.3 The information is vital for estimating carbon budgets on regional and global scales and for understanding their variability under the conditions of climate change. Starting from this requirement a number of CO2 preparations from NBS19 were made at Environment Canada (EC) and analyzed in our laboratories together with Narcis II, a set of well-characterized CO2 samples in sealed tubes available from the National Institute for Environmental Studies (NIES).4,5 Narcis II is very homogeneous in delta13C and delta18O with the isotopic composition close to NBS19-CO2. Among our laboratories the results for delta13C agreed to within +/-0.004 per thousand. The same level of agreement in delta13C was obtained when CO2 was generated from NBS19-calcite using different experimental procedures and conditions in the other two laboratories. For delta18O, the corresponding data were +/-0.011 per thousand when using NBS19-CO2 produced at EC, but discrepancies were enhanced by almost one order of magnitude when NBS19-CO2 was prepared by the other laboratories using slightly different reaction conditions (range=0.13 per thousand).In a second series of experiments, larger amounts of CO2 prepared from NBS19 at the Max-Planck-Institut für Biogeochemie (MPI-BGC) were analyzed together with Narcis II and

  19. Application of stable isotopes (δ{sup 34}S-SO{sub 4}, δ{sup 18}O-SO{sub 4,} δ{sup 15}N-NO{sub 3}, δ{sup 18}O-NO{sub 3}) to determine natural background and contamination sources in the Guadalhorce River Basin (southern Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Urresti-Estala, Begoña, E-mail: b.urresti@uma.es [Universidad de Málaga, Facultad de Ciencias, Grupo de Geodinámica Externa, Campus de Teatinos s/n, 29071 Málaga (Spain); Vadillo-Pérez, Iñaki; Jiménez-Gavilán, Pablo [Universidad de Málaga, Facultad de Ciencias, Grupo de Geodinámica Externa, Campus de Teatinos s/n, 29071 Málaga (Spain); Soler, Albert [Grup de Mineralogia Aplicada i Medi Ambient, Fac. Geologia, Universitat de Barcelona, Barcelona (Spain); Sánchez-García, Damián; Carrasco-Cantos, Francisco [Universidad de Málaga, Facultad de Ciencias, Grupo de Geodinámica Externa, Campus de Teatinos s/n, 29071 Málaga (Spain)

    2015-02-15

    The integrated use of isotopes (δ{sup 34}S-SO{sub 4}, δ{sup 18}O-SO{sub 4,} δ{sup 15}N-NO{sub 3}, δ{sup 18}O-NO{sub 3}), taking into account existing hydrogeological knowledge of the study area (mainly hydrochemical), was applied in the Guadalhorce River Basin (southern Spain) to characterise SO{sub 4}{sup 2−} and NO{sub 3}{sup −} sources, and to quantify natural background levels (NBLs) in groundwater bodies. According to Water Framework Directive 2000/60/EC and, more recently, Groundwater Directive 2006/118/EC, it is important to determine NBLs, as their correct assessment is the first, essential step to characterising groundwater bodies, establishing threshold values, assessing chemical status and identifying trends in pollutant concentrations. In many cases, NBLs are high for some parameters and types of groundwater, making it difficult to distinguish clearly between factors of natural or human origin. The main advantages of using stable isotopes in a complex area like the Guadalhorce River Basin that exhibits widely varying hydrogeological and hydrochemical conditions and longstanding anthropogenic influences (mainly agriculture, but also many others) is accurate determination of pollution sources and precise quantification of NBLs. Since chemical analyses only provides the concentration of pollutants in water and not the source, three isotopic sampling campaigns for sulphates (δ{sup 34}S-SO{sub 4}, δ{sup 18}O-SO{sub 4}) were carried out, in 2006, 2007 and 2012, and another one was conducted for nitrates (δ{sup 15}N-NO{sub 3}, δ{sup 18}O-NO{sub 3}), in 2009, in groundwater bodies in order to trace the origins of each pollutant. The present study identified different pollution sources of dissolved NO{sub 3}{sup −} in groundwater using an isotopic composition and quantified the percentage of natural (lithology, chemical and biological processes) and anthropogenic (fertilisers, manure and sewage) SO{sub 4}{sup 2−} and matched a concentration

  20. Preparation and characterization of H6P2W18O62/Kaolin and its activity on the catalytic synthesis of acetylsalicylic acid%H6P2W18O62/高岭土的制备、表征及催化合成乙酰水杨酸

    Institute of Scientific and Technical Information of China (English)

    曹小华; 王原平; 徐常龙; 雷艳虹; 占昌朝

    2014-01-01

    H6P2W18O62/kaolin was fabricated by dipping Kaolin in the mixing solution of phosphotungstic acid with Dawson structure,and characterized by FT-IR,XRD,SEM and EDS. The catalytic synthesis of acetylsalicylic was carried out as a probe reaction to study the acid catalytic performance of the catalyst,under the optimal condition,i.e. the supported quantity of 40%,w (catalyst)=7.2%(relative to the dosage of salicylic acid),reaction temperature of 90℃,and reaction time of 40min. The average yield of acetylsalicylic acid reaches 90.2%. The catalyst shows good reusability. After its five time usage,the yield of acetylsalicylic acid was still above 85.1%. The catalyst is attractive for esterification by its low cost,high activity,simple post-treatment,no corrosion to the equipment and no pollution.%以高岭土为载体,Dawson结构磷钨酸(H6P2W18O62·13H2O)为活性组分制备了负载型催化剂H6P2W18O62/高岭土,并通过FT-IR、XRD、SEM和EDS对催化剂进行表征。以催化合成乙酰水杨酸为探针反应,考察了催化剂的酸催化性能。结果表明,在优化反应条件为H6P2W18O62负载量为40%,w(H6P2W18O62/高岭土)=7.2%(基于水杨酸的质量),反应温度为90℃,反应时间为40min时,乙酰水杨酸收率达90.2%,催化剂重复使用5次,乙酰水杨酸收率仍可达到85.1%。该催化剂具有价廉易得、催化活性高、后处理工艺简单、不腐蚀设备、无环境污染、可重复使用等优点。

  1. Energy loss straggling data of 28Si, 27Al, 24Mg, 19F, 16O, and 12C heavy ions in thin polymeric Formvar foil over a range of energies 0.1-0.6 MeV/u by time-of-flight spectrometry

    Science.gov (United States)

    Guesmia, A.; Ammi, H.; Msimanga, M.; Dib, A.; Mammeri, S.; Pineda-Vargas, C. A.; Hedibel, M.

    2015-02-01

    The energy-loss straggling of 28Si, 27Al, 24Mg, 19F, 16O and 12C partially stripped heavy ions has been determined in Formvar polymeric thin foil over a continuous range of energies 0.1-0.6 MeV/u, by using a powerful method based on the combination of Heavy Ion-Elastic Recoil Detection Analysis (HI-ERDA) technique and Time of Flight (ToF) spectrometer. The obtained energy loss straggling values have been analyzed and compared with the corresponding computed values adopting some widely used energy loss straggling formulations such as, Bohr, Bethe-Livingston and Yang formulas. The aim of such a comparison is to check the reliability and accuracy of the existing energy loss straggling formulations. The experimental results of energy loss straggling of all ions are found to be significantly greater than those predicted by the theories. These differences can be attributed to the charge exchange straggling. This effect has to be taken into account in order to explain the obtained results.

  2. Measurements of the 24Mg(d,p0,1,2,3,4) and natMg(d,d0) reactions cross sections in the energy range of 1.2-2 MeV for NRA and EBS applications

    Science.gov (United States)

    Rafi-kheiri, H.; Kakuee, O.; Lamehi-Rachti, M.

    2016-04-01

    Differential cross sections of the 24Mg(d,p0,1,2,3,4) reactions were obtained in the range Ed,lab = 1.2-2 MeV and at the scattering angles of 90°, 135°, 150° and 165° using a thin Mg target having thickness of 76.7 ± 3.1 μg/cm2. The cross section values were determined with an average energy step of ∼25 keV while the detailed measurements were carried out with an energy step of ∼5 keV around the resonance peaks. Elastic scattering data for three steep backward angles (135°, 150° and 165°) were also studied for the same incident deuteron energy range and steps. The results were compared with those of the previous studies. Moreover, the validity of the measured data has been benchmarked using a thick Mg target at two deuteron beam energies of 1.7 and 2 MeV.

  3. Controls of {delta}{sup 34}S and {delta}{sup 18}O in dissolved sulphate: Learning from a detailed survey in the Llobregat River (Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Otero, Neus [Departament Cristal . lografia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Marti i Franques, s/n, 08028 Barcelona (Spain); Grup d' Hidrogeoquimica, Departament de Geologia Ambiental, Institut de Ciencies de la Terra ' Jaume Almera' , CSIC, Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain)], E-mail: notero@ub.edu; Soler, Albert; Canals, Angels [Departament Cristal . lografia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Marti i Franques, s/n, 08028 Barcelona (Spain)

    2008-05-15

    The S and O isotopic composition of dissolved SO{sub 4}, used as a tracer for SO{sub 4} sources, was applied to the water of the Llobregat River system (NE Spain). The survey was carried out at 30 sites where surface water was sampled on a monthly basis over a period of 2a. The concentration of dissolved SO{sub 4} varied from 20 to 1575 mg L{sup -1}. Sulphur isotopic compositions clustered in two populations: one - 93% of the samples - had positive values with a mode of +9 per mille ; the other had negative values and a mode of -5 per mille . Data for {delta}{sup 18}O{sub SO{sub 4}} showed a mean value of +11 per mille , with no bi-modal distribution, though lower values of {delta}{sup 18}O corresponded to samples with negative {delta}{sup 34}S. These values can not be explained solely by the contribution of bedrock SO{sub 4} sources: that is, sulphide oxidation and the weathering of outcrops of sulphates, though numerous chemical sediments exist in the basin. Even in a river with a high concentration of natural sources of dissolved SO{sub 4}, such as the Llobregat River, the {delta}{sup 34}S values suggest that dissolved SO{sub 4} is controlled by a complex mix of both natural and anthropogenic sources. The main anthropogenic sources in this basin are fertilizers, sewage, potash mine effluent and power plant emissions. Detailed river water sampling, together with the chemical and isotopic characterisation of the main anthropogenic inputs, allowed determination of the influence of redox processes, as well as identification of the contribution of natural and anthropogenic SO{sub 4} sources and detection of spatial variations and seasonal changes among these sources. For instance, in the Llobregat River the input of fertilisers is well marked seasonally. Minimum values of {delta}{sup 34}S are reported during fertilization periods - from January to March - indicating a higher contribution of this source. The dual isotope approach, {delta}{sup 34}S and {delta}{sup 18}O

  4. Stable isotope composition of inorganic carbonates from Lake Abiyata (Ethiopia): Attempt of reconstructing δ18O palaeohydrological changes during the Holocene

    International Nuclear Information System (INIS)

    Due to the sensitivity of its regional climate to the African monsoon seasonal shifting, Ethiopia has been designated as a key site for palaeoenvironmental reconstructions mainly within the IGBP-PAGES-PEPIII programme. Under the French-Ethiopian ERICA project, we focused on Lake Abiyata located in the Ziway-Shala basin (Central Ethiopia) which has experienced several lacustrine highstands during the Late Pleistocene and Holocene. At present, Lake Abiyata is a closed lake with a very flat catchment area, and corresponds to a half, deep graben infilled by 600-m of sedimentary deposits. In 1995, a 12.6-m-long sequence ABII was cored in Lake Abiyata. A reliable 14C-AMS chronology was defined on both organic matter and inorganic carbonates. Both the modern hydrologeological and geochemical balances of the 'groundwater-lake' system indicate that (i) carbonate cristallization mainly occurs at the water-sediment interface via the mixing of lake water and 14C-depleted groundwaters, and that (ii) modern algae form in equilibrium with the atmospheric reservoir. Phytoplankton is thus considered as an authigenic material, and Core ABII has registered 13,500 cal. yr B.P. of environmental history. The evidence of calcite precipitation at the water-sediment interface calls into question the direct palaeoclimatic reconstruction based on inorganic carbonates. Since the evolution of isotopic contents of carbonates might be linked to the variable proportion of the 'lake/groundwater' end-members in the mixing, calculations based on isotopic mass balance models may allow for the reconstruction of δ18O composition of the lake water. Two major changes can be highlighted: (i) the ∼12,000-5500 cal. yr B.P. period is associated to low 18O contents of lake water, and corresponds to an open hydrological system, with a high lacustrine phytoplanktonic productivity, and (ii) from ∼5500 cal. yr B.P. to Present, regressive conditions are suggested by the δ18O enrichment of the lake water

  5. 2H NMR and 13C-IRMS analyses of acetic acid from vinegar, 18O-IRMS analysis of water in vinegar: International collaborative study report

    International Nuclear Information System (INIS)

    An international collaborative study of isotopic methods applied to control the authenticity of vinegar was organized in order to support the recognition of these procedures as official methods. The determination of the 2H/1H ratio of the methyl site of acetic acid by SNIF-NMR (site-specific natural isotopic fractionation-nuclear magnetic resonance) and the determination of the 13C/12C ratio, by IRMS (isotope ratio mass spectrometry) provide complementary information to characterize the botanical origin of acetic acid and to detect adulterations of vinegar using synthetic acetic acid. Both methods use the same initial steps to recover pure acetic acid from vinegar. In the case of wine vinegar, the determination of the 18O/16O ratio of water by IRMS allows to differentiate wine vinegar from vinegars made from dried grapes. The same set of vinegar samples was used to validate these three determinations. The precision parameters of the method for measuring δ13C (carbon isotopic deviation) were found to be similar to the values previously obtained for similar methods applied to wine ethanol or sugars extracted from fruit juices: the average repeatability (r) was 0.45 per mille , and the average reproducibility (R) was 0.91 per mille . As expected from previous in-house study of the uncertainties, the precision parameters of the method for measuring the 2H/1H ratio of the methyl site were found to be slightly higher than the values previously obtained for similar methods applied to wine ethanol or fermentation ethanol in fruit juices: the average repeatability was 1.34 ppm, and the average reproducibility was 1.62 ppm. This precision is still significantly smaller than the differences between various acetic acid sources (δ13C and δ18O) and allows a satisfactory discrimination of vinegar types. The precision parameters of the method for measuring δ18O were found to be similar to the values previously obtained for other methods applied to wine and fruit juices: the

  6. Assessing the relationship between the δ18O signatures of siliceous sponge spicules and water in a~tropical lacustrine environment (Minas Gerais, Brazil

    Directory of Open Access Journals (Sweden)

    M. C. Matteuzzo

    2013-08-01

    Full Text Available Siliceous sponge spicules constitute an important siliceous component of lacustrine sediments, together with widespread diatom frustules. In contrast to diatom frustules, siliceous spicules are formed in sponges in an enzymatic way. Previous attempts to use their oxygen isotopic signature (δ18Osilica as a paleoenvironmental proxy have led to contradictory conclusions. These attempts demonstrated the need to further assess whether sponges form their silica in oxygen isotopic equilibrium with water. For this reason, we measured the δ18O signature of sponge spicules from a single freshwater species (Metania spinata grown on natural and artificial supports over nine months in a small Brazilian pond (Lagoa Verde, northwestern Minas Gerais. The δ18Osilica values were obtained using the infrared (IR laser-heating fluorination technique following a controlled isotopic exchange (CIE. The δ18O values (δ18Owater and temperature of the pond water were periodically measured and reconstructed over the course of the sponge growth. Assuming that silica may form continuously in the spicules, temperature and δ18Owater values over the months of growth were weighted using a sponge growth coefficient previously established for Metania spinata. The δ18Osilica values of sponges grown simultaneously and on similar substrates were scattered. No relationships were observed between the Δ18Osilica-water and water temperature when the reconstructed values were considered. Conversely, a positive correlation was obtained, with a coefficient of 0.3‰ °C–1 (R2 = 0.63, when δ18Owater values and water temperature at the time of sample collection were considered. Such a positive temperature coefficient clearly indicates that the freshwater sponge Metania spinata does not form its siliceous spicules in oxygen isotopic equilibrium with the pond water. Instead, one or several biologically controlled kinetic fractionation mechanisms may be in play during the various steps

  7. GAS EMISSIONS IN PLANCK COLD DUST CLUMPS—A SURVEY OF THE J = 1-0 TRANSITIONS OF 12CO, 13CO, AND C18O

    International Nuclear Information System (INIS)

    A survey toward 674 Planck cold clumps of the Early Cold Core Catalogue (ECC) in the J = 1-0 transitions of 12CO, 13CO, and C18O has been carried out using the Purple Mountain Observatory 13.7 m telescope. Six hundred seventy-three clumps were detected with 12CO and 13CO emission, and 68% of the sample has C18O emission. Additional velocity components were also identified. A close consistency of the three line peak velocities was revealed for the first time. Kinematic distances are given for all the velocity components, and half of the clumps are located within 0.5 and 1.5 kpc. Excitation temperatures range from 4 to 27 K, slightly larger than those of Td . Line width analysis shows that the majority of ECC clumps are low-mass clumps. Column densities NH2 span from 1020 to 4.5 × 1022 cm–2 with an average value of (4.4 ± 3.6) × 1021 cm–2. NH2 cumulative fraction distribution deviates from the lognormal distribution, which is attributed to optical depth. The average abundance ratio of the 13CO to C18O in these clumps is 7.0 ± 3.8, higher than the terrestrial value. Dust and gas are well coupled in 95% of the clumps. Blue profile asymmetry, red profile asymmetry, and total line asymmetry were found in less than 10% of the clumps, generally indicating that star formation is not yet developed. Ten clumps were mapped. Twelve velocity components and 22 cores were obtained. Their morphologies include extended diffuse, dense, isolated, cometary, and filament, of which the last is the majority. Twenty cores are starless, and only seven cores seem to be in a gravitationally bound state. Planck cold clumps are the most quiescent among the samples of weak red IRAS, infrared dark clouds, UC H II candidates, extended green objects, and methanol maser sources, suggesting that Planck cold clumps have expanded the horizon of cold astronomy.

  8. Determination of the δ2H and δ18O of soil water and water in plant matter; RSIL lab code 1700

    Science.gov (United States)

    Revesz, Kinga M.; Buck, Bryan; Coplen, Tyler B.

    2012-01-01

    The purpose of the Reston Stable Isotope Laboratory lab code 1700 is to determine the δ2H/1H), abbreviated as δ2H, and the δ18O/16O), abbreviated as δ18O, of soil water and water in plant matter. This method is based on the observation that water and toluene form an azeotropic mixture at 84.1 °C. This temperature is substantially lower than the boiling points of water (100 °C) and toluene (110 °C), but water and toluene are immiscible at ambient temperature. The water content of a soil or plant is determined by weighing, drying, and reweighing a small amount of sample. Sufficient sample to collect 3 to 5 milliliters of water after distillation is loaded into a distillation flask. Sufficient toluene is added so that the sample is immersed throughout the entire distillation to minimize evaporation of water, which would affect the δ2H and δ18O values. The mixture of sample and toluene is heated in a flask to its boiling point (84.1 °C) so that water from the sample and toluene can distill together into a specially designed collection funnel. The temperature of 84.1 °C is maintained until the water has been quantitatively transferred to the collection funnel, at which time the temperature is raised to the boiling point of the remaining component (toluene, 110 °C). The collection funnel is maintained at ambient temperature so that the sample water and toluene can be separated physically. After separation, the sample water is purified by addition of paraffin wax to the container with the sample water, capping the container, and heating to approximately 60 °C to melt the wax. Trace amounts of toluene will dissolve in the wax, purifying the sample water for isotopic analysis. The isotopic composition of the purified water is then determined by equilibration with gaseous hydrogen or carbon dioxide, followed by dual-inlet isotope-ratio mass spectrometry. Because laser-absorption spectrometry is sensitive to organic compounds, such as trace toluene remaining in

  9. An Experimental Study on What Controls the Ratios of 18O/16O and 17O/16O of O2 During Microbial Respiration

    Science.gov (United States)

    Stolper, D. A.; Ward, B. B.; Fischer, W. W.; Bender, M. L.

    2015-12-01

    18O/16O and 17O/16O ratios of atmospheric and dissolved oceanic O2 are key biogeochemical tracers of total photosynthesis and respiration on global to local length scales and glacial/interglacial time scales (Luz et al., 1999). Critical to the use of these ratios as biogeochemical tracers is knowledge of how they are affected by production, consumption, and transport of O2. We present new measurements of O2 respiration by E. coli and N. oceanus, an ammonia oxidizing bacterium, to test three assumptions of isotopically enabled models of the O2 cycle: (i) laboratory-measured respiratory 18O/16O isotope effects (18α) of microorganisms are constant under all experimental and natural conditions (e.g., temperature and growth rate); (ii) the respiratory 'mass law' relationship between 18O/16O and 17O/16O [17α = (18α)β] is universal; and (iii) 18α and β for aerobic ammonia and organic carbon oxidation are identical. For E. coli, we find that both 18α and β are variable. From 37°C to 15°C, 18α varies linearly with temperature from 17 to 14‰, and β varies linearly from 0.513 to 0.508. 18α and β do not appear to vary with growth rate (as tested using different carbon sources). Both 18α and β are lower than previous observations for bacteria: 18α = 17-20‰ (Kiddon et al., 1993) and β = 0.515 (Luz and Barkan, 2005). We were able to simulate the observed temperature dependence of 18α and β using a model of respiration with two isotopically discriminating steps: O2 binding to cytochrome bo oxidase (the respiratory enzyme) and reduction of O2 to H2O. Finally, initial results on N. oceanus suggest it has similar values for 18α and β as previously studied aerobic bacteria that consume organic carbon, providing the first support for assumption (iii). Based on these results, isotopically constrained biogeochemical models of O2 cycling may need to consider a temperature dependence for 18α and β for microbial respiration. For example, these results may

  10. A Fiji multi-coral δ18O composite approach to obtaining a more accurate reconstruction of the last two-centuries of the ocean-climate variability in the South Pacific Convergence Zone region

    Science.gov (United States)

    Dassié, Emilie P.; Linsley, Braddock K.; Corrège, Thierry; Wu, Henry C.; Lemley, Gavin M.; Howe, Steve; Cabioch, Guy

    2014-12-01

    The limited availability of oceanographic data in the tropical Pacific Ocean prior to the satellite era makes coral-based climate reconstructions a key tool for extending the instrumental record back in time, thereby providing a much needed test for climate models and projections. We have generated a unique regional network consisting of five Porites coral δ18O time series from different locations in the Fijian archipelago. Our results indicate that using a minimum of three Porites coral δ18O records from Fiji is statistically sufficient to obtain a reliable signal for climate reconstruction, and that application of an approach used in tree ring studies is a suitable tool to determine this number. The coral δ18O composite indicates that while sea surface temperature (SST) variability is the primary driver of seasonal δ18O variability in these Fiji corals, annual average coral δ18O is more closely correlated to sea surface salinity (SSS) as previously reported. Our results highlight the importance of water mass advection in controlling Fiji coral δ18O and salinity variability at interannual and decadal time scales despite being located in the heavy rainfall region of the South Pacific Convergence Zone (SPCZ). The Fiji δ18O composite presents a secular freshening and warming trend since the 1850s coupled with changes in both interannual (IA) and decadal/interdecadal (D/I) variance. The changes in IA and D/I variance suggest a re-organization of climatic variability in the SPCZ region beginning in the late 1800s to period of a more dominant interannual variability, which could correspond to a southeast expansion of the SPCZ.

  11. Geochemical tracers of new production: O2, N2, Ar and δ18O-O2 in surface waters of the subarctic Pacific Ocean

    International Nuclear Information System (INIS)

    The goal of this experiment was to test the utility of geochemical tracers for determining the rate of biological processes in surface waters in the Subarctic Pacific Ocean during the summers of 1987 and 1988. Measurements of O2/Ar, O2/N2 and 18O/16O-O2 by mass spectrometry along with oxygen and 222Rn-226Ra determinations were utilized in a mass balance model to derive rates of net oxygen production. Assuming that O2 production is balanced through a stoichiometric ratio be a net carbon export from the euphotic zone, the authors calculated a carbon export rate of 160 ± 40 mgC m-2d-1. This value is in accordance with sediment trap particulate carbon fluxes and mixed layer NO3 decrease measured in the SUPER program during the same period, implying that oxygen carbon and nitrogen mass balances agree, to within the error of the measurements, in this oceanic location

  12. Search for quasifission in 12C + 238U and 18O + 232Th reactions at near and sub-barrier energies

    International Nuclear Information System (INIS)

    The main motivation of this present work is to study the onset of quasifission process in the fissility region > 0.8. It was observed that angular distribution of fission fragments produced in reaction in this fissility region showed anomalously large anisotropies at subbarrier energies as compared to SSPM, implying presence of pre-equilibrium fission. Here, mass-angle correlation studies of 12C + 238U and 18O + 232Th reactions has been reported, forming same compound nucleus 250Cf (Fissility = 0.86), at similar excitation energy and angular momentum. The measurements were carried out in the energy range Ecm /Vb ∼ 0.88 - 1.1, where Ecm is the energy in centre of mass frame and Vb is the Coulomb barrier

  13. Determination of energy expenditure during heavy exercise, normal daily activity, and sleep using the doubly-labelled-water (/sup 2/H/sub 2/ 18O) method

    Energy Technology Data Exchange (ETDEWEB)

    Stein, T.P.; Hoyt, R.W.; Settle, R.G.; O' Toole, M.; Hiller, W.D.

    1987-03-01

    Energy expenditure of four subjects was measured by the doubly-labelled-water (/sup 2/H/sub 2/ 18O) method to determine if energy expenditure could be determined over short periods. Three subjects were studied while they performed 8 h of heavy exercise in a laboratory environment. Urine and blood samples were taken before and after exercise. Estimated energy expended during 8 h of high-intensity exercise for three subjects was 757 +/- 118 kcal/h by the doubly-labelled-water method using urine and a two-point calculation, which compared favorably with 735 +/- 82 kcal/h obtained by respiratory gas exchange. For the fourth subject, daytime, nighttime, and daily energy expenditure was calculated by both the two-pair method and decay-curve analysis of urine and saliva samples collected in the morning and at night. Daytime and nighttime energy expenditures differed significantly (p less than 0.05).

  14. 34S/32S and 18O/16O ratios of dissolved sulfate from interstitial water samples above gas hydrate bearing sediments of IODP Expedition 311, Cascadia

    Science.gov (United States)

    Wortmann, U. G.; Chernyavsky, B. M.; Torres, M. E.; Kastner, M.

    2008-12-01

    Microbially mediated sulfate reduction affects the isotopic composition of dissolved and solid sulfur species in marine sediments. Although several details of the fractionation process remain controversial, the overall process is well understood and can be described as the sum of several mass dependent fractionations during the stepwise reduction of sulfate to sulfide. Experiments and field data show that the 18O/16O of sulfate is also modified in the presence of sulfate-reducing microorganisms. Here we use a reaction transport model to analyze these processes and to constrain the rates of organotrophic versus methanotrophic sulfate reduction. Our results show that even in cases where sulfate concentrations decline in a linear fashion, up to 50% of all sulfate is consumed by organotrophic sulfate reduction.

  15. A study of some (sd)4 shell model states in 20F via the 18O(3He,p) reaction

    International Nuclear Information System (INIS)

    A microscopic two-particle DWBA analysis is carried out on the 18O(3He,p)20F reaction leading to the (sd)4 positive parity levels. The spectroscopic amplitudes were derived from the three single particle energies and sixty-three two-body matrix elements given by the shell model calculations or Halbert et al. based on an inert 16O core with the additional nucleons distributed in an unrestricted 1d5/2-2s1/2-1d3/2 model space. Angular distributions leading to several 1+, 2+, 3+, 4+ and 5+(sd)4 levels in 20F are fairly well reproduced. (author). 21 refs, 4 figs, 3 tabs

  16. Independent cross-sections of alkali isotopes produced in various targets bombarded by $^{12}C$ and $^{18}O$ ions up to 77 MeV/amu

    CERN Document Server

    De Saint-Simon, M; Coc, A; Epherre-Rey-Campagnolle, Marcelle; Guimbal, P; Haan, S; Langevin, M; Müller, A C; Thibault, C; Touchard, F

    1982-01-01

    The authors report on an online mass-spectrometric study of the isotopic distributions of nuclear reaction products. The two purposes of this experiment are the investigation of a particular aspect of reaction-mechanisms and the study of the possibility for exotic-nuclei production. The measurements have been carried out with the 86 MeV/amu /sup 12/C and /sup 18/O beams of the synchrocyclotron SC (CERN). By degradation in different sets of graphite slabs, three different energies: 13, 27 and 77 MeV/amu have been chosen. Due to the chemical selectivity for the alkali elements of the device, the isotopic distributions of Li, Na, K, Rb, Cs and Fr were measured in four targets: C, Nb, Ta and U. The independent yields obtained by direct ion counting are converted in cross-sections using a calibration of T. Lund et al.

  17. Inhibition of α/β-K6P2W18O62· 10H2O on the Activity of Mushroom Tyrosinase and Its Antimicrobial Effects

    Institute of Scientific and Technical Information of China (English)

    HU Xi-yu; CHEN Bing-nian; WANG Li; CHEN Fa-he

    2012-01-01

    Dawson-type phosphotungstic polyoxometalate a/β-K6P2W18O62·10H2O(P2W18) was synthesized and its inhibitory effect on the mushroom tyrosinase was investigated.It could inhibit diphenolase activity of mushroom tyrosinase as an irreversible inhibitor.When the concentration of the enzyme reached 0.0176 mg/mL,the concentration of P2W18 leading to 50% activity lost(IC50) was 0.05 mmol/L for monophenolase and 0.64 mmol/L for diphenolase.In addition,the antimicrobial activity of P2W18 was evaluated by zone of inhibition test.The results show that P2W18 possesses effective antimicrobial ability against Escherichia coli,Bacillus subtilis,yeast,especially Escherichia coli and yeast.

  18. Analysis of metal radioisotope impurities generated in [{sup 18}O]H{sub 2}O during the cyclotron production of fluorine-18

    Energy Technology Data Exchange (ETDEWEB)

    Gillies, J.M. [Cancer Research-UK/UMIST Radiochemical Targeting and Imaging Group, Christie Hospital NHS Trust, Paterson Institute for Cancer Research, Wilmslow Road, Manchester, M20 4BX (United Kingdom)]. E-mail: jgillies@picr.man.ac.uk; Najim, N. [Cancer Research-UK/UMIST Radiochemical Targeting and Imaging Group, Christie Hospital NHS Trust, Paterson Institute for Cancer Research, Wilmslow Road, Manchester, M20 4BX (United Kingdom); School of Chemical Engineering and Analytical Sciences, University of Manchester, P.O. Box 88, Manchester, M60 1QD (United Kingdom); Zweit, J. [Cancer Research-UK/UMIST Radiochemical Targeting and Imaging Group, Christie Hospital NHS Trust, Paterson Institute for Cancer Research, Wilmslow Road, Manchester, M20 4BX (United Kingdom); School of Chemical Engineering and Analytical Sciences, University of Manchester, P.O. Box 88, Manchester, M60 1QD (United Kingdom)

    2006-04-15

    We show the separation of metal radioistope impurities using capillary electrophoresis (CE). The methodology used is an improvement of existent protocols for separation of stable metal ions. Production of fluorine-18 using [{sup 18}O]H{sub 2}O-enriched water encased in a titanium target body results in the production of several metal radioisotope impurities. Optimisation of the conditions for CE separation of the metal radioisotope impurities incorporated the use of 6 mM 18-Crown-6 in combination with 12 mM glycolic acid as complexing agents within the running buffer (10 mM pyridine, pH 4.0). Using this optimised procedure, we were able to separate and detect a number of metal radioisotopes, including chromium, cobalt, manganese, vanadium and berillium, within the fM concentration range.

  19. Study on particle emission in the light-heavy ion fussion reactions: 14N, sup(16,18) O + 12C

    International Nuclear Information System (INIS)

    From the energy spectra of light particles produced in light heavy ion induced reactions, level densities of the final nuclei as well as the critical angular momenta for fussion may be obtained. The 14N, sup(16,18) O + 12C reactions were investigated in the energy range 30 MeV < E sub(LAB) < 60 MeV. Detailed angular distributions of the light particles (p, d, t, α) emitted in the process were obtained. Fits of the magnitude and shape of the spectra, by means of statistical model calculations were used to extract final nuclei level densities. The shape of the spectra and the ratio σ(α) σ(p) are shown to be sensitive to the fussion critical angular momentum (J sub(cr)), offering an alternative method for the total fussion cross-section determination. (Author)

  20. CO/sub 2/ production in animals: analysis of potential errors in the doubly labeled water method. [/sup 3/H and /sup 18/O

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, K.A.

    1979-03-01

    Laboratory validation studies indicate that doubly labeled water (/sup 3/HH/sup 18/O and /sup 2/HH/sup 18/O) measurements of CO/sub 2/ production are accurate to within +-9% in nine species of mammals and reptiles, a bird, and an insect. However, in field studies, errors can be much larger under certain circumstances. Isotopic fraction of labeled water can cause large errors in animals whose evaporative water loss comprises a major proportion of total water efflux. Input of CO/sub 2/ across lungs and skin caused errors exceeding +80% in kangaroo rats exposed to air containing 3.4% unlabeled CO/sub 2/. Analytical errors of +-1% in isotope concentrations can cause calculated rates of CO/sub 2/ production to contain errors exceeding +-70% in some circumstances. These occur: 1) when little decline in isotope concentractions has occured during the measurement period; 2) when final isotope concentrations closely approach background levels; and 3) when the rate of water flux in an animal is high relative to its rate of CO/sub 2/ production. The following sources of error are probably negligible in most situations: 1) use of an inappropriate equation for calculating CO/sub 2/ production, 2) variations in rates of water or CO/sub 2/ flux through time, 3) use of H/sub 2/O-18 dilution space as a measure of body water volume, 4) exchange of 0-18 between water and nonaqueous compounds in animals (including excrement), 5) incomplete mixing of isotopes in the animal, and 6) input of unlabeled water via lungs and skin. Errors in field measurements of CO/sub 2/ production can be reduced to acceptable levels (< 10%) by appropriate selection of study subjects and recapture intervals.

  1. Coordinated Isotopic and Mineral Characterization of Highly Fractionated 18O-Rich Silicates in the Queen Alexandra Range 99177 CR3 Chondrite

    Science.gov (United States)

    Nguyen, A. N.; Keller, L. P.; Messenger, S.; Rahman, Z.

    2016-01-01

    Carbonaceous chondrites contain a mixture of solar system condensates, pre-solar grains, and primitive organic matter. Each of these materials record conditions and processes in different regions of the solar nebula, on the meteorite parent body, and beyond the solar system. Oxygen isotopic studies of meteorite components can trace interactions of distinct oxygen isotopic reservoirs in the early solar system and secondary alteration processes. The O isotopic compositions of the earliest solar system condensates fall along a carbonaceous chondrite anhydrous mineral (CCAM) line of slope approximately 1 in a plot of delta 17O against delta 18O. This trend is attributed to mixing of material from 16O-poor and 16O-rich reservoirs. Secondary processing can induce mass-dependent fractionation of the O isotopes, shifting these compositions along a line of slope approximately 0.52. Substantial mass-dependent fractionation of O isotopes has been observed in secondary minerals in CAIs, calcite, and FUN inclusions. These fractionations were caused by significant thermal or aqueous alteration. We recently reported the identification of four silicate grains with extremely fractionated O isotopic ratios (delta 18O equals 37 - 55 per mille) in the minimally altered CR3 chondrite QUE 99177. TEM analysis of one grain indicates it is a nebular condensate that did not experience substantial alteration. The history of these grains is thus distinct from those of the aforementioned fractionated materials. To constrain the origin of the silicate grains, we conducted further Mg and Fe isotopic studies and TEM analyses of two grains.

  2. Decadal time scale variability recorded in the Quelccaya summit ice core {delta}{sup 18}O isotopic ratio series and its relation with the sea surface temperature

    Energy Technology Data Exchange (ETDEWEB)

    Melice, J.L. [Louvain Univ., Louvain-la-Neuve (Belgium). Inst. d`Astronomie et de Geophysique; Roucou, P. [Centre de Recherches de Climatologie, Universite de Bourgogne, Faculte des Sciences Gabriel, B.P. 138, F-21000 Dijon (France)

    1998-02-01

    The spectral characteristics of the {delta}{sup 18}O isotopic ratio time series of the Quelccaya ice cap summit core are investigated with the multi taper method (MTM), the singular spectrum analysis (SSA) and the wavelet transform (WT) techniques for the 500 y long 1485-1984 period. The most significant (at the 99.8% level) cycle according to the MTM F-test has a period centered at 14.4 y while the largest variance explaining oscillation according to the SSA technique has a period centered at 12.9 y. The stability over time of these periods is investigated by performing evolutive MTM and SSA on the 500 y long {delta}{sup 18}O series with a 100 y wide moving window. It is shown that the cycles with largest amplitude and that the oscillations with largest extracting variance have corresponding periods aggregated around 13.5 y that are very stable over the period between 1485 and 1984. The WT of the same isotopic time series reveals the existence of a main oscillation around 12 y which are also very stable in time. The relation between the isotopic data at Quelccaya and the annual sea surface temperature (SST) field anomalies is then evaluated for the overlapping 1919-1984 period. Significant global correlation and significant coherency at 12.1 y are found between the isotopic series and the annual global sea surface temperature (GSST) series. Moreover, the correlation between the low (over 8 y) frequency component of the isotopic time series and the annual SST field point out significant values in the tropical North Atlantic. This region is characterized by a main SST variability at 12.8 y. (orig.) With 13 figs., 2 tabs., 52 refs.

  3. Reconstruction of drip-water δ18O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave (Germany

    Directory of Open Access Journals (Sweden)

    T. Kluge

    2013-02-01

    Full Text Available The geochemical signature of many speleothems used for reconstruction of past continental climates is affected by kinetic isotope fractionation. This limits quantitative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilibrium effects. The extent of kinetic fractionation co-varies in Δ47 and δ18O so that it can be used to account for disequilibrium in δ18O and to extract the past drip-water composition. Here we apply this approach to stalagmites from Bunker Cave (Germany and calculate drip-water δ18Ow values for the Eemian, MIS3, and the Holocene, relying on independent temperature estimates and accounting for disequilibrium. Applying the co-variation method to modern calcite precipitates yields drip-water δ18Ow values in agreement with modern cave drip-water δ18Ow of −7.9 ± 0.3‰, despite large and variable disequilibrium effects in both calcite δ18Oc and Δ47. Reconstructed paleo-drip-water δ18Ow values are lower during colder periods (e.g., MIS3: −8.6 ± 0.4‰ and the early Holocene at 11 ka: −9.7 ± 0.2‰ and show higher values during warmer climatic periods (e.g., the Eemian: −7.6 ± 0.2‰ and the Holocene Climatic Optimum: −7.2 ± 0.3‰. This new approach offers a unique possibility for quantitative climate reconstruction including the assessment of past hydrological conditions while accounting for disequilibrium effects.

  4. Reconstruction of drip-water δ18O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave (Germany

    Directory of Open Access Journals (Sweden)

    A. Wackerbarth

    2012-07-01

    Full Text Available The geochemical signature of many speleothems used for reconstruction of past continental climates is affected by kinetic isotope fractionation. This limits quantitative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilibrium effects. The extent of kinetic fractionation co-varies in Δ47 and δ18O so that it can be used to account for disequilibrium in δ18O and to extract the past drip-water composition. Here we apply this approach to stalagmites from Bunker Cave (Germany and calculate drip-water δ18Ow values for the Eemian, Marine Isotope Stage (MIS 3, and the Holocene, relying on independent temperature estimates and accounting for disequilibrium. Applying the co-variation method to modern calcite precipitates yields drip-water δ18Ow values in agreement with modern cave drip-water δ18Ow of −7.9 ± 0.3‰, despite large and variable disequilibrium effects in both calcite δ18Oc and Δ47. Reconstructed paleo-drip-water δ18Ow values are lower during colder periods (e.g., MIS 3: −8.5 ± 0.4‰ and the early Holocene at 11 kyr: −9.3 ± 0.1‰ and show higher values during warmer climatic periods (e.g., the Eemian: −7.5 ± 0.2‰ and the Holocene Climatic Optimum: −7.2 ± 0.3‰. This new approach offers a unique possibility for quantitative climate reconstruction including the assessment of past hydrological conditions while accounting for disequilibrium effects.

  5. Twentieth century sea surface temperature and salinity variations at Timor inferred from paired coral δ18O and Sr/Ca measurements

    Science.gov (United States)

    Cahyarini, Sri Yudawati; Pfeiffer, Miriam; Nurhati, Intan Suci; Aldrian, Edvin; Dullo, Wolf-Christian; Hetzinger, Steffen

    2014-07-01

    The Indonesian Throughflow (ITF), which represents the global ocean circulation connecting the Pacific Warm Pool to the Indian Ocean, strongly influences the Indo-Pacific climate. ITF monitoring since the late 1990s using mooring buoys have provided insights on seasonal and interannual time scales. However, the absence of longer records limits our perspective on its evolution over the past century. Here, we present sea surface temperature (SST) and salinity (SSS) proxy records from Timor Island located at the ITF exit passage via paired coral δ18O and Sr/Ca measurements spanning the period 1914-2004. These high-resolution proxy based climate data of the last century highlights improvements and cautions when interpreting paleoclimate records of the Indonesian region. If the seasonality of SST and SSS is not perfectly in phase, the application of coral Sr/Ca thermometry improves SST reconstructions compared to estimates based on coral δ18O only. Our records also underline the importance of ocean advection besides rainfall on local SSS in the region. Although the El Niño/Southern Oscillation (ENSO) causes larger anomalies relative to the Indian Ocean Dipole (IOD), Timor coral-based SST and SSS records robustly correlate with IOD on interannual time scales, whereas ENSO only modifies Timor SST. Similarly, Timor SST and SSS are strongly linked to Indian Ocean decadal-scale variations that appear to lead Timor oceanographic conditions by about 1.6-2 years. Our study sheds new light on the complex signatures of Indo-Pacific climate modes on SST and SSS dynamics of the ITF. This article was corrected on 8 AUG 2014. See the end of the full text for details.

  6. Natural chlorate in the environment: Application of a new IC-ESI/MS/MS method with a Cl18O3- internal standard

    Science.gov (United States)

    Rao, Balaji; Hatzinger, Paul B.; Böhlke, John Karl; Sturchio, Neil C.; Andraski, Brian J.; Eckardt, Frank D.; Jackson, W. Andrew

    2010-01-01

    A new ion chromatography electrospray tandem mass spectrometry (IC-ESI/MS/MS) method has been developed for quantification and confirmation of chlorate (ClO3-) in environmental samples. The method involves the electro-chemical generation of isotopically labeled chlorate internal standard (Cl18O3-) using 18O water (H218O). The standard was added to all samples prior to analysis thereby minimizing the matrix effects that are associated with common ions without the need for expensive sample pretreatments. The method detection limit (MDL) for ClO3- was 2 ng L-1 for a 1 mL volume sample injection. The proposed method was successfully applied to analyze ClO3- in difficult environmental samples including soil and plant leachates. The IC-ESI/MS/MS method described here was also compared to established EPA method 317.0 for ClO3- analysis. Samples collected from a variety of environments previously shown to contain natural perchlorate (ClO 4-) occurrence were analyzed using the proposed method and ClO3- was found to co-occur with ClO4- at concentrations ranging from 500 mg kg-1 in caliche salt deposits from the Atacama Desert in Chile. Relatively low concentrations of ClO3- in some natural groundwater samples (-1) analyzed in this work may indicate lower stability when compared to ClO4- in the subsurface. The high concentrations of ClO3- in caliches and soils (3-6 orders of magnitude greater) as compared to precipitation samples indicate that ClO3-, like ClO4-, may be atmospherically produced and deposited, then concentrated in dry soils, and is possibly a minor component in the biogeochemical cycle of chlorine.

  7. Reconstructing climate processes driving variability in precipitation sources from mid to late Holocene speleothem δ18O records from the Southwest US

    Science.gov (United States)

    Wong, C. I.; Nusbaumer, J. M.; Banner, J.

    2015-12-01

    Independent co-variation of speleothem δ18O values and other moisture-sensitive speleothem proxies (e.g., growth rate, trace element concentrations) in recently published Holocene stalagmite records from Texas and New Mexico suggest a decoupling between precipitation amounts and precipitation sources over the southwest US. There is, however, limited understanding of the relation between precipitation sources and precipitation amounts and the climate processes governing variability in the region's precipitation sources. To address this, we use source water tags to track precipitation derived from Pacific and Atlantic Oceans during a simulation of modern (1975-2013) climate. We find distinct patterns in the spatial distribution of the fraction of Pacific-derived winter precipitation are associated with unique atmospheric states. High pressure ridging reflected by 500 hPa geopotential heights result in weaker zonal winds and stronger northerly winds over the western US. Under these conditions, Pacific-derived moisture propagates further to the east, and Atlantic-derived moisture is suppressed over southern US. Conversely, 500 hPa geopotential heights that are latitudinally streamline result in strong zonal winds across the entire US. Under these conditions, the fraction of West Pacific-derived precipitation is limited to higher latitudes, and the fraction of far East Pacific- and Atlantic-derived precipitation is enhanced across the Southwest and Southern US, respectively. Further analysis of this data set will assess the teleconnections that link the distinct atmospheric conditions over the US with the state of the ocean and atmosphere over the Pacific and Atlantic Oceans. The results will be applied to reconstructing variability in the climate dynamics governing moisture transport to the southwest US during the mid to late Holocene as reflected by speleothem δ18O records in the region.

  8. Cobalt Polyoxometalate Co4V2W18O68(10-): A Critical Investigation of Its Synthesis, Purity, and Observed (51)V Quadrupolar NMR.

    Science.gov (United States)

    Folkman, Scott J; Kirner, Joel T; Finke, Richard G

    2016-06-01

    The vanadium-containing cobalt polyoxometalate (Co-POM) Co4V2W18O68(10-) (hereafter Co4V2W18) has been reported to be a stable, homogeneous water-oxidation catalyst, one with a claimed record turnover frequency that is also reportedly 200-fold faster than its phosphorus congener, Co4P2W18O68(10-). The claimed superior water-oxidation catalysis activity of the vanadium congener, Co4V2W18, rests squarely on the reported synthesis of Co4V2W18, its purity, and its stability in both the solid-state and in solution. Attempts to repeat the preparation of Co4V2W18 by either of two literature syntheses, along with the other studies reported herein, led to the discovery of multiple, convoluted problems in the prior literature of Co4V2W18. The three most serious of those problems proved to be the prior misunderstanding of the quadrupolar (herein (51)V) NMR peak widths in complexes that also contain paramagnetic metals such as Co(II), the incorrect assignment of a -506.8 ppm (51)V NMR to Co4V2W18, and then the use of that -506.8 peak to argue for the stability of Co4V2W18 in solution. The results are reported in a somewhat historical, "story" fashion en route to elucidating and fully supporting the 11 insights and take-home messages listed in the Summary and Conclusions section. PMID:27159211

  9. Microwave-enhanced electrochemical cycling performance of the LiNi0.2Mn1.8O4 spinel cathode material at elevated temperature.

    Science.gov (United States)

    Raju, Kumar; Nkosi, Funeka P; Viswanathan, Elumalai; Mathe, Mkhulu K; Damodaran, Krishnan; Ozoemena, Kenneth I

    2016-05-14

    The well-established poor electrochemical cycling performance of the LiMn2O4 (LMO) spinel cathode material for lithium-ion batteries at elevated temperature stems from the instability of the Mn(3+) concentration. In this work, a microwave-assisted solid-state reaction has been used to dope LMO with a very low amount of nickel (i.e., LiNi0.2Mn1.8O4, herein abbreviated as LMNO) for lithium-ion batteries from Mn3O4 which is prepared from electrolytic manganese oxide (EMD, γ-MnO2). To establish the impact of microwave irradiation on the electrochemical cycling performance at an elevated temperature (60 °C), the Mn(3+) concentration in the pristine and microwave-treated LMNO samples was independently confirmed by XRD, XPS, (6)LiMAS-NMR and electrochemical studies including electrochemical impedance spectroscopy (EIS). The microwave-treated sample (LMNOmic) allowed for the clear exposure of the {111} facets of the spinel, optimized the Mn(3+) content, promoting structural and cycle stability at elevated temperature. At room temperature, both the pristine (LMNO) and microwave-treated (LMNOmic) samples gave comparable cycling performance (>96% capacity retention and ca. 100% coulombic efficiency after 100 consecutive cycling). However, at an elevated temperature (60 °C), the LMNOmic gave an improved cycling stability (>80% capacity retention and ca. 90% coulombic efficiency after 100 consecutive cycling) compared to the LMNO. For the first time, the impact of microwave irradiation on tuning the average manganese redox state of the spinel material to enhance the cycling performance of the LiNi0.2Mn1.8O4 at elevated temperature and lithium-ion diffusion kinetics has been clearly demonstrated. PMID:27113855

  10. Environmental isotopes (18O, 2H, and 87Sr/86Sr) as a tool in groundwater investigations in the Keta Basin, Ghana

    Science.gov (United States)

    Jørgensen, Niels; Banoeng-Yakubo, Bruce

    2001-03-01

    Analyses of environmental isotopes (18O, 2H, and 87Sr/86Sr) are applied to groundwater studies with emphasis on saline groundwater in aquifers in the Keta Basin, Ghana. The 87Sr/86Sr ratios of groundwater and surface water of the Keta Basin primarily reflect the geology and the mineralogical composition of the formations in the catchments and recharge areas. The isotopic compositions of 18O and 2H of deep groundwater have small variations and plot close to the global meteoric water line. Shallow groundwater and surface water have considerably larger variations in isotopic compositions, which reflect evaporation and preservation of seasonal fluctuations. A significant excess of chloride in shallow groundwater in comparison to the calculated evaporation loss is the result of a combination of evaporation and marine sources. Groundwaters from deep wells and dug wells in near-coastal aquifers are characterized by relatively high chloride contents, and the significance of marine influence is evidenced by well-defined mixing lines for strontium isotopes, and hydrogen and oxygen stable isotopes, with isotopic compositions of seawater as one end member. The results derived from environmental isotopes in this study demonstrate that a multi-isotope approach is a useful tool to identify the origin and sources of saline groundwater. Résumé. L'analyse des isotopes du milieu (18O, 2H, et 87Sr/86Sr) a été mise en œuvre pour des études hydrogéologiques portant sur des eaux souterraines salées des aquifères du bassin de Keta (Ghana). Les rapports isotopiques 87Sr/86Sr de l'eau souterraine et de l'eau de surface du bassin de Keta reflètent principalement la géologie et la composition minéralogique des formations des bassins d'alimentation et des zones de recharge. Les compositions isotopiques en 18O et en 2H des eaux souterraines profondes présentent de faibles variations et se placent près de la droite des eaux météoriques mondiales. Les eaux des nappes peu profondes

  11. Environmental isotopes (18O, 2H, and 87Sr/86Sr) as a tool in groundwater investigations in the Keta Basin, Ghana

    Science.gov (United States)

    Jørgensen, Niels; Banoeng-Yakubo, Bruce

    2001-03-01

    Analyses of environmental isotopes (18O, 2H, and 87Sr/86Sr) are applied to groundwater studies with emphasis on saline groundwater in aquifers in the Keta Basin, Ghana. The 87Sr/86Sr ratios of groundwater and surface water of the Keta Basin primarily reflect the geology and the mineralogical composition of the formations in the catchments and recharge areas. The isotopic compositions of 18O and 2H of deep groundwater have small variations and plot close to the global meteoric water line. Shallow groundwater and surface water have considerably larger variations in isotopic compositions, which reflect evaporation and preservation of seasonal fluctuations. A significant excess of chloride in shallow groundwater in comparison to the calculated evaporation loss is the result of a combination of evaporation and marine sources. Groundwaters from deep wells and dug wells in near-coastal aquifers are characterized by relatively high chloride contents, and the significance of marine influence is evidenced by well-defined mixing lines for strontium isotopes, and hydrogen and oxygen stable isotopes, with isotopic compositions of seawater as one end member. The results derived from environmental isotopes in this study demonstrate that a multi-isotope approach is a useful tool to identify the origin and sources of saline groundwater. Résumé. L'analyse des isotopes du milieu (18O, 2H, et 87Sr/86Sr) a été mise en œuvre pour des études hydrogéologiques portant sur des eaux souterraines salées des aquifères du bassin de Keta (Ghana). Les rapports isotopiques 87Sr/86Sr de l'eau souterraine et de l'eau de surface du bassin de Keta reflètent principalement la géologie et la composition minéralogique des formations des bassins d'alimentation et des zones de recharge. Les compositions isotopiques en 18O et en 2H des eaux souterraines profondes présentent de faibles variations et se placent près de la droite des eaux météoriques mondiales. Les eaux des nappes peu profondes

  12. Effects of recharge and discharge on delta2H and delta18O composition and chloride concentration of high arsenic/fluoride groundwater from the Datong Basin, northern China.

    Science.gov (United States)

    Xie, Xianjun; Wang, Yanxin; Su, Chunli; Duan, Mengyu

    2013-02-01

    To better understand the effects of recharge and discharge on the hydrogeochemistry of high levels of arsenic (As) and fluoride (F) in groundwater, environmental isotopic composition (delta2H and delta18O) and chloride (Cl) concentrations were analyzed in 29 groundwater samples collected from the Datong Basin. High arsenic groundwater samples (As > 50 micog/L) were found to be enriched in lighter isotopic composition that ranged from -92 to -78 per thousand for deuterium (delta2H) and from -12.5 to -9.9 per thousand for oxygen-18 (delta18O). High F-containing groundwater (F > 1 mg/L) was relatively enriched in heavier isotopic composition and varied from -90 to -57 per thousand and from -12.2 to -6.7 per thousand for delta2H and delta18O, respectively. High chloride concentrations and delta18O values were primarily measured in groundwater samples from the northern and southwestern portions of the study area, indicating the effect of evaporation on groundwater. The observation of relatively homogenized and low delta18O values and chloride concentrations in groundwater samples from central part of the Datong Basin might be a result of fast recharge by irrigation returns, which suggests that irrigation using arsenic-contaminated groundwater affected the occurrence of high arsenic-containing groundwater in the basin.

  13. Effects of recharge and discharge on delta2H and delta18O composition and chloride concentration of high arsenic/fluoride groundwater from the Datong Basin, northern China.

    Science.gov (United States)

    Xie, Xianjun; Wang, Yanxin; Su, Chunli; Duan, Mengyu

    2013-02-01

    To better understand the effects of recharge and discharge on the hydrogeochemistry of high levels of arsenic (As) and fluoride (F) in groundwater, environmental isotopic composition (delta2H and delta18O) and chloride (Cl) concentrations were analyzed in 29 groundwater samples collected from the Datong Basin. High arsenic groundwater samples (As > 50 micog/L) were found to be enriched in lighter isotopic composition that ranged from -92 to -78 per thousand for deuterium (delta2H) and from -12.5 to -9.9 per thousand for oxygen-18 (delta18O). High F-containing groundwater (F > 1 mg/L) was relatively enriched in heavier isotopic composition and varied from -90 to -57 per thousand and from -12.2 to -6.7 per thousand for delta2H and delta18O, respectively. High chloride concentrations and delta18O values were primarily measured in groundwater samples from the northern and southwestern portions of the study area, indicating the effect of evaporation on groundwater. The observation of relatively homogenized and low delta18O values and chloride concentrations in groundwater samples from central part of the Datong Basin might be a result of fast recharge by irrigation returns, which suggests that irrigation using arsenic-contaminated groundwater affected the occurrence of high arsenic-containing groundwater in the basin. PMID:23472327

  14. Preparation of H6P2W18 O62/TiO2 by different templates and microwave assisted photocatalyse%不同模板剂作用下H6P2W18O62/TiO2的制备与微波辅助光催化

    Institute of Scientific and Technical Information of China (English)

    李莉; 计远; 王瑞卿; 路露

    2011-01-01

    A series of H6P2W18O62/TiO2 photocatalysts were prepared by a one-step sol-gel-hydrothermai technique in the presence of the nonionic surfactant triblock-poly(ethylene oxide)-poly(propylene oxide)-(ethylene oxide)copolymer(P123) ,polyethylene glycol octadecyl ether polyoxyethulene 10 stearyl ether(C18H37(OCH2CH2)l0OH) (Brij-76) ,cation surfactant C21H38C1N ? H2O(CPC) ,C19H42BrN(CTAB)and anion surfactant C12H25NaO4S(SDS). The phase structures,chemical composition,optical absorption properties and surface physicochemical properties were characterized via fourier transform infrared ( FTIR) spectrum, X-ray diffraction(XRD) ,inductively coupled plasma atomic emission spectroscopy (ICP-AES) ,nitrogen adsorption/desorption, transmission electron microscopy(TEM)and scanning electron microscope with energy dispersive spectrometer(SEM-EDS). The results indicated that the basic structure of H6P2W18O62 in the composite H6P2W18O62/TiO2 had been basically maintained. The surface area and the structrue of the composite were different in a large extent The surface area of H6P2W18O62/TiO2(P123) composite was up to 414. 6 m /g. The photocatalytic activities of the as-prepared materials were studied by the microwave assisted photodegradation of methyl orange. The results showed that the photocatalytic activities of H6P2W18O62/TiO2(P123)were the best under the microwaveirradiation,and the degradation rate of methyl orange was over 88%within 60 minutes.%分别采用非离子表面活性剂(C3H6O·C2H4O)x(P123)和C18H37(OCH2CH2)1oOH(Brij-76)、阳离子表面活性剂C21H38CIN·H2O(CPC)和C19H42BrN(CTAB)以及阴离子表面活性剂C12H25 NaO4S(SDS)作为模板剂,通过溶胶-凝胶再结合程序升温溶剂热一步法制备了系列复合光催化材料H6P2W18 O62/TiO2.通过傅立叶-红外光谱(FTIR)、X-射线衍射(XRD)、电感耦合等离子体原子发射光谱(ICP-AES)、氮气吸附-脱附测定、透射电子显微镜(TEM)以及扫描电子显微镜配合X-射线能量

  15. Evolution of Interannual and Decadal/Interdecadal variability of the SPCZ since the late 18th century using a network of Fiji coral δ18O time-series

    Science.gov (United States)

    Dassie, E. P.; Linsley, B. K.; Correge, T.; Wu, H. C.; Lemley, G. M.; Cabioch, G.

    2012-12-01

    The South Pacific Convergence Zone (SPCZ) region is of high interest due to its impact on tropical rainfall and the export of moisture from the tropics. Documenting the amplitude and periodicity of SPCZ displacements on interannual (mainly influenced by El Niño Southern Oscillation (ENSO)) and decadal/interdecadal (D/I) time-scales is of high importance not only for risk management but also for understanding the dynamics of the SPCZ and for improving General Circulation Model climate predictions. We have generated a unique regional coral δ18O network from the Fiji Islands, which are located just south of the main SPCZ rainfall axis. This network consists of five monthly-resolved coral δ18O time-series from different regions of Fiji. Evaluation of interseries correlation coefficients indicates that ENSO-band (2 to 9 years) and D/I-band (10 to 50 years) δ18O variability is highly reproducible. Correlation to instrumental surface salinity (SSS) data indicates that interannual coral δ18O variability in Fiji is the result of interannual changes in SSS that are coupled to ENSO. The composite reconstruction (arithmetic average of the five Fiji δ18O records), extending from 1790 to 2004 AD, was compared to known climatic indices such as the Southern Oscillation and Interdecadal Pacific Oscillation indices over the 20th century. Pearson Product-Moment correlations between the coral δ18O composite and these target indices of the Pacific basin are r= 0.71 and 0.41 for ENSO and D/I timescales respectively, with p-values better than 0.001. These high values indicate that our Fiji composite δ18O record is suitable for reconstructing past ENSO and D/I variability prior to the instrumental record. Our Fiji ENSO-band and D/I-band reconstructions from the Southwest Pacific also share important similarities with other Pacific coral δ18O records such as the δ18O record from Malo-Channel (Vanuatu). The Fiji composite δ18O reconstruction also correlates negatively with

  16. An Unprecedented 1D Zigzag Chain Alkaline Earth Metal Derivative {[Ba(DMF)3(H2O)2][Ba(DMF)4]2(P2W18O62)}n Containing Dawson Heteropolyanion

    Institute of Scientific and Technical Information of China (English)

    Jing Ping WANG; Jian Ru MA; Jing Yang NIU

    2006-01-01

    An unprecedented 1D zigzag chain alkaline earth metal derivative, {[Ba(DMF)3(H2O)2][Ba(DMF)4]2(P2W18O62)}n, (DMF=N, N-dimethyl formamide) containing Dawson heteropolyanion has been successfully synthesized and characterized by X-ray crystallography. Two barium cations bridged by three DMF ligands in parallel combination with the Dawson-type heteropolyanion [P2W18O62]6- and then the resulting subunits {[Ba(DMF)4]2(P2W18O62)}2+ are alternately linked together via another [Ba(DMF)3(H2O)2]2+ ions, constructing a 1D zigzag chain architecture.

  17. Method for determination of .sup.18 O/.sup.16 O and .sup.2 H/.sup.1 H ratios and .sup.3 H (tritium) concentrations of xylem waters and subsurface waters using time series sampling

    Science.gov (United States)

    Smith, Brian; Menchaca, Leticia

    1999-01-01

    A method for determination of .sup.18 O/.sup.16 O and .sup.2 H/.sup.1 H ratios and .sup.3 H concentrations of xylem and subsurface waters using time series sampling, insulating sampling chambers, and combined .sup.18 O/.sup.16 O, .sup.2 H/.sup.1 H and .sup.3 H concentration data on transpired water. The method involves collecting water samples transpired from living plants and correcting the measured isotopic compositions of oxygen (.sup.18 O/.sup.16 O) and hydrogen (.sup.2 H/.sup.1 H and/or .sup.3 H concentrations) to account for evaporative isotopic fractionation in the leafy material of the plant.

  18. FieldSpec: A field portable mass spectrometer prototype for high frequency measurements of δ (2) H and δ (18) O ratios in water

    Science.gov (United States)

    López Días, Veneranda; Quang Hoang, Hung; Martínez-Carreras, Núria; Barnich, François; Wirtz, Tom; Pfister, Laurent; McDonnell, Jeffrey

    2016-04-01

    Hydrological studies relying on stable water isotopes to better understand water sources, flowpaths and transit times are currently limited by the coarse temporal resolution of sampling and analysis protocols. At present, two kinds of lab-based instruments are used : (i) the standard isotope ratio mass spectrometers (IRMS) [1] and (ii) the laser-based instruments [2, 3]. In both cases, samples need to be collected in the field and then transferred to the laboratory for the water isotopic ratio measurements (even further complex sample preparation is required for the IRMS). Hence, past and ongoing research targets the development of field deployable instruments for measuring stable water isotopes at high temporal frequencies. While recent studies have demonstrated that laser-based instruments may be taken to the field [4, 5], their size and power consumption still restrict their use to sites equipped with mains power or generators. Here, we present progress on the development of a field portable mass spectrometer (FieldSpec) for direct high frequency measurements of δ2H and δ18O ratios in water. The FieldSpec instrument is based upon the use of a double focusing magnetic sector mass spectrometer in combination with an electron impact ion source and a membrane dual inlet system. The instrument directly collects liquid water samples in the field, which are then converted into water vapour before being injected into the mass spectrometer for the stable isotope analysis. δ2H and δ18O are derived from the measured mass spectra. All the components are arranged in a vacuum case having a suit case type dimension with portable electronics and battery. Proof-of-concept experiments have been carried out to characterize the instrument. The results show that the FieldSpec instrument has good linearity (R2 = 0.99). The reproducibility of the instrument ranges between 1 and 4 ‰ for δ2H and between 0.1 and 0.4 ‰ for δ18O isotopic ratio measurements. A measurement

  19. Seasonal variations recorded in cave monitoring results and a 10 year monthly resolved speleothem δ18O and δ13C record from the Han-sur-Lesse cave, Belgium

    Science.gov (United States)

    Van Rampelbergh, M.; Verheyden, S.; Allan, M.; Quinif, Y.; Keppens, E.; Claeys, P.

    2014-04-01

    Speleothems provide paleoclimate information on multi-millennial to decadal scales in the Holocene. However seasonal or even monthly resolved records remain scarce. They require fast growing stalagmites and a good understanding of the proxy transfer function on very short time scales. The Proserpine stalagmite from the Han-sur-Less cave (Belgium) displays seasonal layers of 0.5 to 2 mm thickness that reconstruct paleoclimates at a monthly scale. Through a regular cave monitoring, we acquired a good understanding of how δ18O and δ13C signals in modern calcite reflect climate variations on sub-seasonal scale. Cave parameters vary seasonally in response to the activity of the vegetation cover and outside air temperature. From December to June, the cave remains in "winter-mode". Outside temperatures are cold inducing low cave air and water temperatures. Bio-productivity in the soil is limited leading to low pCO2, higher δ13C composition of the CO2 in the cave air and high discharge due to the inactivity of the plant coverage. From June to December, the cave switches to "summer-mode" and the measured factors display an opposite behavior. The δ18O and δ13C signals of fresh calcite precipitated on glass slabs vary seasonally. Lowest δ18O values occur during the summer-mode when the δ13C values are high. The δ18O composition of the calcite is in equilibrium with the drip water δ18O and display seasonal variations due to changes in the cave air and water temperature. In contrast to the δ18O signal, δ13C values of the calcite precipitated on the glass slabs do not reflect equilibrium conditions. Highest δ13C values occur during summer, when discharge rates are low increasing the evaporation effect on the thin water film covering the stalagmite. This same antithetical behavior of the δ18O vs. the δ13C signals is seen in the monthly resolved speleothem record that covers the period between 1976 and 1985 AD. Dark layers are formed during summer, while light layers

  20. Seasonal variations recorded in cave monitoring results and a 10 year monthly resolved speleothem δ18O and δ13C record from the Han-sur-Lesse cave, Belgium

    Directory of Open Access Journals (Sweden)

    M. Van Rampelbergh

    2014-04-01

    Full Text Available Speleothems provide paleoclimate information on multi-millennial to decadal scales in the Holocene. However seasonal or even monthly resolved records remain scarce. They require fast growing stalagmites and a good understanding of the proxy transfer function on very short time scales. The Proserpine stalagmite from the Han-sur-Less cave (Belgium displays seasonal layers of 0.5 to 2 mm thickness that reconstruct paleoclimates at a monthly scale. Through a regular cave monitoring, we acquired a good understanding of how δ18O and δ13C signals in modern calcite reflect climate variations on sub-seasonal scale. Cave parameters vary seasonally in response to the activity of the vegetation cover and outside air temperature. From December to June, the cave remains in "winter-mode". Outside temperatures are cold inducing low cave air and water temperatures. Bio-productivity in the soil is limited leading to low pCO2, higher δ13C composition of the CO2 in the cave air and high discharge due to the inactivity of the plant coverage. From June to December, the cave switches to "summer-mode" and the measured factors display an opposite behavior. The δ18O and δ13C signals of fresh calcite precipitated on glass slabs vary seasonally. Lowest δ18O values occur during the summer-mode when the δ13C values are high. The δ18O composition of the calcite is in equilibrium with the drip water δ18O and display seasonal variations due to changes in the cave air and water temperature. In contrast to the δ18O signal, δ13C values of the calcite precipitated on the glass slabs do not reflect equilibrium conditions. Highest δ13C values occur during summer, when discharge rates are low increasing the evaporation effect on the thin water film covering the stalagmite. This same antithetical behavior of the δ18O vs. the δ13C signals is seen in the monthly resolved speleothem record that covers the period between 1976 and 1985 AD. Dark layers are formed during summer

  1. The climate reconstruction in Shandong Peninsula, northern China, during the last millennium based on stalagmite laminae together with a comparison to δ18O

    Science.gov (United States)

    Wang, Qing; Zhou, Houyun; Cheng, Ke; Chi, Hong; Shen, Chuan-Chou; Wang, Changshan; Ma, Qianqian

    2016-04-01

    Stalagmite ky1, with a length of 75 mm and the upper part (from top to 42.769 mm depth) consisting of 678 laminae, was collected from Kaiyuan Cave in the coastal area of Shandong Peninsula, northern China, located in a warm temperate zone in the East Asia monsoon area. Based on high-precision dating with the U-230Th technique and continuous counting of laminae, the 1st and 678th laminae have been confirmed to be AD 1894 ± 20 and 1217 ± 20 from top to bottom, respectively. By the measurement of laminae thickness and δ18O ratios, we haved obtained the time series data of thickness of laminae and δ18O ratios from AD 1217 ± 20 to 1894 ± 20, analyzed the climatic-environmental meaning of variations in the thickness of laminae, which have a good correspondence with the cumulative departure curve of the drought-waterlog index in the historical period. The results show that, in the ˜ 678 years from AD 1217 ± 20 to 1894 ± 20, both the thickness of the laminae and the degree of fluctuation in the thickness of the laminae of stalagmite ky1 have obvious stages of variation and are completely synchronized with the contemporaneous intensity of the summer monsoons and precipitation as time changed. There is a negative correlation between the thickness of the laminae and the summer monsoon intensity and precipitation. There is a positive correlation between the degree of fluctuation in the thickness of the laminae and both the intensity of the summer monsoons and the precipitation. Therefore, for the Kaiyuan Cave in the coastal area of both the warm temperate zone and the East Asia monsoon area, the variations in the thickness of the laminae are not only related to the change in the climatic factors themselves but also related to the degree of climatic stability. In the coastal area belonging to the warm temperate zone and the East Asia monsoon area, the climate change between the LIA (Little Ice Age) and the MWP (Medieval Warm Period), in addition to less precipitation

  2. Multi-tracer approach (18O, 3H/3He, CFC, SF6, 35S) to find the best emergency drinking water supply, Vorarlberg, Austria

    Science.gov (United States)

    Kralik, Martin; Vergnaud, Virginie; Uriostegui, Stephanie; Esser, Bradley

    2016-04-01

    To provide an emergency drinking water supply in case of catastrophic events (regional chemical accidents, floods, earth quakes etc.), wells and springs should be known which are fed by a large reservoir. Such reservoirs provide a good filtering capacity and long Mean Residence Times (MRTs) of the raw water. Their existence allows to use these resources for longer periods excluding the danger of contamination. This provides the water authorities the necessary time to set measures to protect the general water supply. After preselection of 16 wells and springs all over the territory of the province of Vorarlberg at the western end of Austria by the local water authority, these wells and springs were measured (water temperature, electric conductivity, pH and dissolved oxygen content) and sampled monthly for δ 18O/2H measurements over the winter half-year 2013/14. At the same time the tritium concentrations of the October and March samples were measured as well. Based on the variation of the monthly on-site measurements and the δ 18O/2H results 12 wells and springs were selected for further investigations. On these sites samples for 3H/3He, CFC-11/12/113, SF6 and sulphur-35 measurements were collected in August 2014. As expected from a humid alpine area, non of the selected springs or wells showed really long MRTs. Five out of 16 investigated sites are regarded as well suited to be used as emergency water source with a range of MRTs of 9 - 30 years. Five springs and wells are regarded of limited suitability due to the shorter MRTs of 5 - 9 years. In two springs the 3H/3He method could not be applied due to He-degassing in a karst-system and during sampling. CFC and SF6 excess at some sites with anthropogenic and geogenic sources hampered the utilisation of these gases as dating tool, but they were useful as source tracers. Sulphur-35 was detected in two wells only, indicating contribution of very young water (water supply. In general, the combination of tracers

  3. Hydrochemical and isotopic (2H, 18O and 37Cl) constraints on evolution of geothermal water in coastal plain of Southwestern Guangdong Province, China

    Science.gov (United States)

    Chen, Liuzhu; Ma, Teng; Du, Yao; Xiao, Cong; Chen, Xinming; Liu, Cunfu; Wang, Yanxin

    2016-05-01

    Geothermal energy is abundant in Guangdong Province of China, however, majority of it is still unexploited. To take full advantage of this energy, it is essential to know the information of geothermal system. Here, physical parameters such as pH and temperature, major ion (Na+, Ca2 +, Mg2 +, Cl-, SO42 - and HCO3-), trace elements (Br-, Sr2 +, Li+ and B3 +) and stable isotopes (2H, 18O and 37Cl) in geothermal water, non-geothermal water (river water, cold groundwater) and seawater were used to identify the origin and evolution of geothermal water in coastal plain of Southwest of Guangdong. Two separate groups of geothermal water have been identified in study area. Group A, located in inland of study area, is characterized by Na+ and HCO3-. Group B, located in coastal area, is characterized by Na+ and Cl-. The relationships of components vs. Cl for different water samples clearly suggest the hydrochemical differences caused by mixing with seawater and water-rock interactions. It's evident that water-rock interactions under high temperature make a significant contribution to hydrochemistry of geothermal water for both Group A and Group B. Besides, seawater also plays an important role during geothermal water evolution for Group B. Mixing ratios of seawater with geothermal water for Group B are calculated by Cl and Br binary diagram, the estimated results show that about geothermal water, and seawater might get into the geothermal system by deep faults. Molar Na/Cl ratios also support these two processes. Geothermal and non-geothermal water samples plot around GMWL in the δ2H vs. δ18O diagram, indicating that these samples have a predominant origin from meteoric water. Most of geothermal water samples display δ37Cl values between those of the non-geothermal water and seawater samples, further reveals three sources of elements supply for geothermal water, including atmospheric deposition, bedrocks and seawater, which show a great potential to trace source of

  4. Evaluation of continuous water vapor δD and δ18O measurements by off-axis integrated cavity output spectroscopy

    Science.gov (United States)

    Kurita, N.; Newman, B. D.; Araguas-Araguas, L. J.; Aggarwal, P.

    2012-08-01

    Recent commercially available laser spectroscopy systems enabled us to continuously and reliably measure the δD and δ18O of atmospheric water vapor. The use of this new technology is becoming popular because of its advantages over the conventional approach based on cold trap collection. These advantages include much higher temporal resolution/continuous monitoring and the ability to make direct measurements of both isotopes in the field. Here, we evaluate the accuracy and precision of the laser based water vapor isotope instrument through a comparison of measurements with those found using the conventional cold trap method. A commercially available water vapor isotope analyzer (WVIA) with the vaporization system of a liquid water standard (Water Vapor Isotope Standard Source, WVISS) from Los Gatos Research (LGR) Inc. was used for this study. We found that the WVIA instrument can provide accurate results if (1) correction is applied for time-dependent isotope drift, (2) normalization to the VSMOW/SLAP scale is implemented, and (3) the water vapor concentration dependence of the isotopic ratio is also corrected. In addition, since the isotopic value of water vapor generated by the WVISS is also dependent on the concentration of water vapor, this effect must be considered to determine the true water vapor concentration effect on the resulting isotope measurement. To test our calibration procedure, continuous water vapor isotope measurements using both a laser instrument and a cold trap system were carried out at the IAEA Isotope Hydrology Laboratory in Vienna from August to December 2011. The calibrated isotopic values measured using the WVIA agree well with those obtained via the cold trap method. The standard deviation of the isotopic difference between both methods is about 1.4‰ for δD and 0.28‰ for δ18O. This precision allowed us to obtain reliable values for d-excess. The day-to-day variation of d-excess measured by WVIA also agrees well with that found

  5. Identifying residence times and streamflow generation processes using δ18O and δ2H in meso-scale catchments in the Abay/Upper Blue Nile, Ethiopia

    Directory of Open Access Journals (Sweden)

    S. Tekleab

    2013-08-01

    Full Text Available Measurements of the stable isotopes oxygen-18 (18O and deuterium (2H were carried out in two meso-scale catchments, Chemoga (358 km2 and Jedeb (296 km2 south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin. Stable isotope composition in precipitation, spring water and streamflow were analyzed (i to characterize the spatial and temporal variations of water fluxes; (ii to estimate the mean residence time of water using a sine wave regression approach; and (iii to identify runoff components using classical two component hydrograph separations at a seasonal time scale. The results show that the isotopic composition of precipitation exhibit marked seasonal variations, which suggests different sources of moisture generation for the rainfall in the study area. The Atlantic–Indian ocean, Congo basin, and the Sud swamps are the likely the potential moisture source areas during the main rainy (summer season. While, the Indian–Arabian, and Mediterranean Sea moisture source areas during little rain (spring, and dry (winter seasons. The spatial variation of the isotopic composition is affected by the amount effect and to less extent by altitude and temperature effects. A mean altitude effect of −0.12‰ (100 m−1 for 18O and −0.58‰ (100 m−1 for 2H were discernable in precipitation isotope composition. The seasonal variations of the isotopic signature of the spring water exhibit a damped response as compared to the river waters, which shows that the spring water has longer residence times than the river water. Results from the hydrograph separation at a seasonal time scale indicate the dominance of event water with an average of 71% and 64% of the total runoff during the wet season in the Chemoga and Jedeb catchment, respectively. The stable isotope compositions of streamflow samples were damped compared to the input function of precipitation for both catchments

  6. Using δ15N and δ18O values to identify sources of nitrate in karstic springs in the Paris basin (France)

    International Nuclear Information System (INIS)

    Highlights: • δ15N and δ18O allowed characterizing nitrate sources in two karstic springs. • Respective endmembers contributions were quantified with Bayesian model. • Sp1 is supplied by different endmembers with the same range of proportions. • Sp2 is mainly fed by agriculture and chalk nitrates. - Abstract: In many parts of the world, groundwater quality deterioration is occurring often due to changes in land use along with overexploitation of some aquifers. Some of the drinking water distributed in Paris (France) is collected from a karstic Cretaceous chalk aquifer at two groups of springs located 80 km south of Paris, in the Lunain catchment. Although geographically close to each other, these springs (Sp1 and Sp2) have quite different hydrogeochemical characteristics. In Sp1, an increase in the NO3- concentrations of 18 mg L−1 (from 16 mg L−1 in 1965 to 34 mg L−1 in 2009) has been observed and in Sp2, NO3- concentrations have increased by 26 mg L−1 (from 20 mg L−1 in 1965 to 46 mg L−1 in 2009). The origin of the NO3- was, however, unclear. The stable isotopic composition of NO3- was used to identify the sources causing the increase of NO3- concentrations and to assess seasonal variations. The isotopic composition of two potential sources including agricultural effluents and wastewater was determined. Likewise, two additional NO3- sources, the chalk groundwater and the Lunain River water, were considered, following the hydrogeological context of the Lunain catchment. Determination the concentrations and the δ15N and δ18O values of spring water NO3- and the use of a Bayesian isotopic mixing model SIAR (Stable Isotope Analyses in R) allowed determination of the proportional contribution of respective NO3- sources in the springs. In spring Sp1, all the potential NO3- sources (4) contributed almost equally during the low flow period, but higher NO3- contributions from the agricultural source and the chalk groundwater were observed during the

  7. Evaluation of continuous water vapor δD and δ18O measurements by off-axis integrated cavity output spectroscopy

    Directory of Open Access Journals (Sweden)

    L. J. Araguas-Araguas

    2012-08-01

    Full Text Available Recent commercially available laser spectroscopy systems enabled us to continuously and reliably measure the δD and δ18O of atmospheric water vapor. The use of this new technology is becoming popular because of its advantages over the conventional approach based on cold trap collection. These advantages include much higher temporal resolution/continuous monitoring and the ability to make direct measurements of both isotopes in the field. Here, we evaluate the accuracy and precision of the laser based water vapor isotope instrument through a comparison of measurements with those found using the conventional cold trap method. A commercially available water vapor isotope analyzer (WVIA with the vaporization system of a liquid water standard (Water Vapor Isotope Standard Source, WVISS from Los Gatos Research (LGR Inc. was used for this study. We found that the WVIA instrument can provide accurate results if (1 correction is applied for time-dependent isotope drift, (2 normalization to the VSMOW/SLAP scale is implemented, and (3 the water vapor concentration dependence of the isotopic ratio is also corrected. In addition, since the isotopic value of water vapor generated by the WVISS is also dependent on the concentration of water vapor, this effect must be considered to determine the true water vapor concentration effect on the resulting isotope measurement. To test our calibration procedure, continuous water vapor isotope measurements using both a laser instrument and a cold trap system were carried out at the IAEA Isotope Hydrology Laboratory in Vienna from August to December 2011. The calibrated isotopic values measured using the WVIA agree well with those obtained via the cold trap method. The standard deviation of the isotopic difference between both methods is about 1.4‰ for δD and 0.28‰ for δ18O. This precision allowed us to obtain reliable values for d-excess. The day-to-day variation of d-excess measured by WVIA also agrees well

  8. Evaluation of continuous water vapor δD and δ18O measurements by off-axis integrated cavity output spectroscopy

    Directory of Open Access Journals (Sweden)

    L. J. Araguas-Araguas

    2012-04-01

    Full Text Available Recent commercially available laser spectroscopy systems enabled us to continuously and reliably measure the δD and δ18O of atmospheric water vapor. The use of this new technology is becoming popular because of its advantages over the conventional approach based on cold trap collection. These advantages include much higher temporal resolution/continuous monitoring and the ability to make direct measurements of both isotopes in the field. Here, we evaluate the accuracy and precision of the laser based water vapor isotope instrument through a comparison of measurements with those found using the conventional cold trap method. A commercially available water vapor isotope analyzer (WVIA with the vaporization system of a liquid water standard (Water Vapor Isotope Standard Source, WVISS from Los Gatos Research (LGR Inc. was used for this study. We found that the WVIA instrument can provide accurate results if: (1 correction is applied for time-dependent isotope drift, (2 normalization to the VSMOW/SLAP scale is implemented, and (3 the water vapor concentration dependence of the isotopic ratio is also corrected. In addition, since the isotopic value of water vapor generated by the WVISS is also dependent on the concentration of water vapor, this effect must be considered to determine the true water vapor concentration effect on the resulting isotope measurement. To test our calibration procedure, continuous water vapor isotope measurements using both a laser instrument and a cold trap system were carried out at the IAEA Isotope Hydrology Laboratory in Vienna from August to December 2011. The calibrated isotopic values measured using the WVIA agree well with those obtained via the cold trap method. The standard deviation of the isotopic difference between both methods is about 1.4‰ for δD and 0.28‰ for δ18O. This precision allowed us to obtain reliable values for d-excess. The day-to-day variation of d-excess measured by WVIA also agrees well

  9. Partitioning Net Ecosystem Carbon Exchange Into net Assimilation and Respiration With Canopy-scale Isotopic Measurements: an Error Propagation Analysis With Both 13C and 18O Data

    Science.gov (United States)

    Peylin, P.; Ogee, J.; Cuntz, M.; Bariac, T.; Ciais, P.; Brunet, Y.

    2003-12-01

    Stable CO2 isotope measurements are increasingly used to partition the net CO2 exchange between terrestrial ecosystems and the atmosphere in terms of non-foliar respiration (FR) and gross photosynthesis (FA). However the accuracy of the partitioning strongly depends on the isotopic disequilibrium between these two gross fluxes and a rigorous estimation of the errors on FA and FR is needed. In this study we account and propagate uncertainties on all terms in the mass balance equations for total and "labeled" CO2 in order to get precise estimates of the errors on FA and FR. We applied our method to a maritime pine forest in the Southwest of France. Using the δ 13C-CO2 and CO2 measurements, we show that the resulting uncertainty associated to the gross fluxes can be as large as 4 æmol m-2 s-1. In addition, even if we could get more precise estimates of the isoflux and the isotopic signature of FA we show that this error would not be significantly reduced. This is because the isotopic disequilibrium between FA and FR is around 2-3‰ , i.e. the order of magnitude of the uncertainty on the isotopic signature of FR (δ R). With δ 18O-CO2 and CO2 measurements, the uncertainty associated to the gross fluxes lies also around 4 æmol m-2 s-1. On the other hand, it could be dramatically reduced if we were able to get more precise estimates of the CO18O isoflux and the associated discrimination during photosynthesis. This is because the isotopic disequilibrium between FA and FR is large, of the order of 10-15‰ , i.e. much larger than the uncertainty on δ R. The isotopic disequilibrium between FA and FR or the uncertainty on δ R vary among ecosystems and over the year. Our approach may help to choose the best strategy to study the carbon budget of a given ecosystem using stable isotopes.

  10. Electrical transport properties of CoMn0.2−xGaxFe1.8O4 ferrites using complex impedance spectroscopy

    Directory of Open Access Journals (Sweden)

    Chien-Yie Tsay

    2016-05-01

    Full Text Available In this study, we report the influence of Ga content on the microstructural, magnetic, and AC impedance properties of Co-based ferrites with compositions of CoMn0.2−xGaxFe1.8O4 (x=0, 0.1, and 0.2 prepared by the solid-state reaction method. Experimental results showed that the as-prepared Co-based ferrites had a single-phase spinel structure; the Curie temperature of Co-based ferrites decreased with increasing Ga content. All ferrite samples exhibited a typical hysteresis behavior with good values of saturation magnetization at room temperature. The electrical properties of Co-based ferrites were investigated using complex impedance spectroscopy analysis in the frequency range of 100 kHz-50 MHz at temperatures of 150 to 250 oC. The impedance analysis revealed that the magnitudes of the real part (Z’ and the imaginary part (Z” of complex impedance decreased with increasing temperature. Only one semicircle was observed in each complex impedance plane plot, which revealed that the contribution to conductivity was from the grain boundaries. It was found that the relaxation time for the grain boundary (τgb also decreased with increasing temperature. The values of resistance for the grain boundary (Rgb significantly increased with increasing Ga content, which indicated that the incorporation of Ga into Co-based ferrites enhanced the electrical resistivity.

  11. Electrical transport properties of CoMn0.2-xGaxFe1.8O4 ferrites using complex impedance spectroscopy

    Science.gov (United States)

    Tsay, Chien-Yie; Lin, Yi-Hsiang; Wang, Yao-Ming; Chang, Horng-Yi; Lei, Chien-Ming; Jen, Shien-Uang

    2016-05-01

    In this study, we report the influence of Ga content on the microstructural, magnetic, and AC impedance properties of Co-based ferrites with compositions of CoMn0.2-xGaxFe1.8O4 (x=0, 0.1, and 0.2) prepared by the solid-state reaction method. Experimental results showed that the as-prepared Co-based ferrites had a single-phase spinel structure; the Curie temperature of Co-based ferrites decreased with increasing Ga content. All ferrite samples exhibited a typical hysteresis behavior with good values of saturation magnetization at room temperature. The electrical properties of Co-based ferrites were investigated using complex impedance spectroscopy analysis in the frequency range of 100 kHz-50 MHz at temperatures of 150 to 250 oC. The impedance analysis revealed that the magnitudes of the real part (Z') and the imaginary part (Z") of complex impedance decreased with increasing temperature. Only one semicircle was observed in each complex impedance plane plot, which revealed that the contribution to conductivity was from the grain boundaries. It was found that the relaxation time for the grain boundary (τgb) also decreased with increasing temperature. The values of resistance for the grain boundary (Rgb) significantly increased with increasing Ga content, which indicated that the incorporation of Ga into Co-based ferrites enhanced the electrical resistivity.

  12. Herschel measurements of the D/H and 16O/18O ratios in water in the Oort-cloud comet C/2009 P1 (Garradd)

    CERN Document Server

    Bockelée-Morvan, D; Swinyard, B; de Val-Borro, M; Crovisier, J; Hartogh, P; Lis, D C; Moreno, R; Szutowicz, S; Lellouch, E; Emprechtinger, M; Blake, G A; Courtin, R; Jarchow, C; Kidger, M; Küppers, M; Rengel, M; Davis, G R; Fulton, T; Naylor, D; Sidher, S; Walker, H

    2012-01-01

    The D/H ratio in cometary water is believed to be an important indicator of the conditions under which icy planetesimals formed and can provide clues to the contribution of comets to the delivery of water and other volatiles to Earth. Available measurements suggest that there is isotopic diversity in the comet population. The Herschel Space Observatory revealed an ocean-like ratio in the Jupiter-family comet 103P/Hartley 2, whereas most values measured in Oort-cloud comets are twice as high as the ocean D/H ratio. We present here a new measurement of the D/H ratio in the water of an Oort-cloud comet. HDO, H_2O, and H_2^18O lines were observed with high signal-to-noise ratio in comet C/2009 P1 (Garradd) using the Herschel HIFI instrument. Spectral maps of two water lines were obtained to constrain the water excitation. The D/H ratio derived from the measured H_2^16O and HDO production rates is 2.06+/-0.22 X 10**-4. This result shows that the D/H in the water of Oort-cloud comets is not as high as previously th...

  13. Morphology and kinematics of the gas envelope of protostar L1527 as obtained from ALMA observations of the C$^{18}$O(2-1) line emission

    CERN Document Server

    Tuan-Anh, P; Hoai, D T; Diep, P N; Phuong, N T; Thao, N T; Darriulat, P

    2016-01-01

    Using ALMA observations of the C$^{18}$O(2-1) line emission of the gas envelope of protostar L1527, we have reconstructed in space its morphology and kinematics under the assumption of axisymmetry about the west-east axis. We present evidence for rotation with a power law requiring an index increasing with decreasing distance from the star, as expected from a transition to Keplerian. The total velocity, interpreted as free-fall velocity, corresponds to a protostar mass of 0.2 solar masses. The very strong absorption slightly above systemic velocity prevents a reliable exploration at distances from the protostar smaller than $\\sim$100 AU. The in-fall velocity, evaluated from the kinematics of the envelope without reference to this absorption, is found to be small and its variation over the explored range is poorly constrained. The accretion rate is evaluated at the scale of 2.5$\\pm$1.0 10$^{-7}$ M$_{\\odot}$. Deviations from a simple isothermal, stationary description are quantified. The overall morphology leav...

  14. Niobium sputtered Havar foils for the high-power production of reactive [18F]fluoride by proton irradiation of [18O]H2O targets.

    Science.gov (United States)

    Wilson, J S; Avila-Rodriguez, M A; Johnson, R R; Zyuzin, A; McQuarrie, S A

    2008-05-01

    Niobium sputtered Havar entrance foils were used for the production of reactive [(18)F]fluoride by proton irradiation of [(18)O]H(2)O targets under pressurized conditions. The synthesis yield in the routine production of 2-[(18)F]fluoro-2-deoxy-glucose (FDG) was used as an indicative parameter of the reactivity of (18)F. The yield of FDG obtained with (18)F produced in a target with Havar foil was used as a baseline. No statistically significant difference was found in the saturated yields of (18)F when using Havar or Havar-Nb sputtered entrance foils. However, the amount of long-lived radionuclidic impurities decreased more than 10-fold using the Havar-Nb entrance foil. The average decay corrected synthesis yield of FDG, evaluated over a period of more than 2 years, was found to be approximately 5% higher when using a Havar-Nb entrance foil and a marked improvement on the FDG yield consistency was noted. In addition, the frequency of target rebuilding was greatly diminished when using the Nb sputtered entrance foil. PMID:18242099

  15. Shellfish, seasonality, and sedentism : δ18O analysis of California mussels from early Holocene shell middens on San Miguel Island, California

    International Nuclear Information System (INIS)

    We estimate seasonality of shellfish harvest and site occupation for four Early Holocene shell middens on California's San Miguel Island using a dataset of 449 δ18O measurements from 84 mussel shells (Mytilus californianus). Seasonality was assigned to prehistoric mussels using paleo sea-surface temperature (PSST) estimates from isotopic data obtained across full shell profiles. The results suggest that PSSTs around San Miguel Island were generally cooler between ∼10,000-8600 calBP and that mussels were harvested in a range of water temperatures which suggest a mix of seasonal and year round harvesting at the four sites. Two substantial shell middens dated to ∼10,000 and ∼9000 calBP appear to have been residential basecamps where Paleocoastal peoples harvested shellfish during all four seasons. These data suggest that Early Holocene peoples occupied the Channel Islands year round and highlight the importance of stable isotope analysis of marine shells for helping evaluate human settlement and subsistence strategies along the Pacific Coast. (author)

  16. First high resolution analysis of the ν1 +ν2 and ν2 +ν3 bands of S18O2

    Science.gov (United States)

    Ulenikov, O. N.; Bekhtereva, E. S.; Gromova, O. V.; Zamotaeva, V. A.; Kuznetsov, S. I.; Sydow, C.; Maul, C.; Bauerecker, S.

    2016-08-01

    The Fourier-transformed infrared spectra of the ν1 +ν2 and ν2 +ν3 bands of S18O2 were recorded for the first time in the region 1580-1850 cm-1 and theoretically analyzed. About 940 and 1210 transitions were assigned in the experimental spectra with the maximum values of quantum numbers Jmax. / Kamax. equal to 60/20 and 60/21 to the bands ν1 +ν2 and ν2 +ν3 . The weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account Coriolis resonance interaction between the vibrational states (110) and (011) and Fermi interaction between the states (110) and (030). To make the ro-vibrational analysis physically more suitable, the initial values of main spectroscopic parameters have been estimated from the values of corresponding parameters of the S16O2 species on the basis of the results of the isotopic substitution theory. Finally, the set of 26 spectroscopic parameters obtained from the fit reproduces values of 1229 initial "experimental" ro-vibrational energy levels (about 2150 transitions assigned in the experimental spectra) with the drms = 1.8 ×10-4cm-1 .

  17. Carbon cycling in primary production bottle incubations: inferences from grazing experiments and photosynthetic studies using 14C and 18O in the Arabian Sea

    Science.gov (United States)

    Laws, Edward A.; Landry, Michael R.; Barber, Richard T.; Campbell, Lisa; Dickson, Mary-Lynn; Marra, John

    Estimates of photosynthesis based on the incorporation of 14C-labeled inorganic carbon into particulate carbon were compared to estimates of gross photosynthesis based on net O 2 production and the production of 18O2 from H218O during the US Joint Global Ocean Flux Study (US JGOFS) Arabian Sea process cruises. For samples incubated below the surface and at optical depthsMehler reaction, photorespiration, dark respiration, excretion, and grazing effects on the two estimates of photosynthesis. The 14C uptake : gross photosynthesis ratio was distinctly higher (0.62) for samples incubated at the surface. This result is likely due to UV light effects, since the O 2 and 14C incubations were done in quartz and polysulfone bottles, respectively. The 14C uptake : gross photosynthesis ratio was lower (0.31) for bottles incubated at optical depths>3. This result probably reflects an increase in the ratio of dark respiration to net photosynthesis in the vicinity of the compensation light level.

  18. A quick cooling event of the East Asian monsoon responding to Heinrich Event 1: Evidence from stalagmite δ18O records

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on TIMS U-series dating results and annual band counting method, an annual-resolution time scale from 17450 to 14420 aBP has been established for a stalagmite from the Hulu Cave at Tangshan, Nanjing. A high-resolution oxygen isotopic record reveals decadral-centural oscillations in air temperature in the East Asian monsoon climate area during the last glacial maximum. The most conspicuous feature in the oxygen isotopic record in the period is the particular cold event synchronized with the last Heinrich event (H1) in the northern Atlantic deep-sea records. This particular cold event, beginning at 16140 ( 100 aBP, shows a rapid cooling down with a magnitude of 7-8℃ in air temperature within 36 years. Furthermore, (6)18O record demonstrates that the event lasted 790 years with gradually warming tendency (10 cycles of air temperature oscillations) after the remarkable cooling down. We believed that this unique pattern of event recorded in the stalagmite ? 8O might be controlled by various factors including changes of insolation at mid-latitude Northern Hemisphere, the southern extend of the last ice-rafted event in the North Atlantic and changes of the Equatorial Pacific sea surface temperature.

  19. Long-term trend and abrupt events of the Holocene Asian monsoon inferred from a stalagmite δ18O record from Shennongjia in Central China

    Institute of Scientific and Technical Information of China (English)

    SHAO Xiaohua; WANG Yongjin; CHENG Hai; KONG Xinggong; WU Jiangying; EDWARDS R. Lawrence

    2006-01-01

    A high-resolution oxygen-isotope record from a thorium-uranium-dated stalagmite from Shanbao Cave at Shennongjia reflects variations in the amount of monsoon precipitation for the period from 11.5 to 2.1 ka (1 ka = 1000 cal aBP). Between 11.5 and 9.3 ka, a sharp decrease in δ18O indicates a rapid increase in monsoon precipitation. An interval of generally high monsoon precipitation is observed between 9.3 and 4.4 ka. An arid period has prevailed between 4.4 and 2.1 ka. The long-term trend of Shanbao record appears to follow summer insolation at 33°N latitude. An abrupt decrease in monsoon precipitation around 4.3 ka is synchronous with the collapse of Neolithic culture in central China. This abrupt change could have resulted from the amplification of the gradually decreased summer insolation by the positive vegetation-atmosphere-aerosol feedback. The weakened Asian monsoon events were in concert with decreased Greenland temperature during the early Holocene, centered at 8.2, 8.6, 9.3, 10.2 and 11.0 ka. This correlation suggests that changes in low-latitude monsoon are connected with climate change in high-latitude polar region.

  20. High-precision 13C and 18O measurements by continuous flow-isotope ratio mass spectrometry (CF-IRMS) in Romanian wines characterization

    International Nuclear Information System (INIS)

    Wines characterization is an important problem to which isotopic analysis by continuous flow- IRMS has made a significant contribution. The use of mass spectrometry (MS) to determine the ratios of stable isotopes in bio-molecules now provides the means to prove the botanical and geographical origin of a wide variety of foodstuffs - and therefore, to authenticate and eliminate fraud. There is a strong need for reliable and validated methods to ensure compliance with such regulation and to protect the interests of the consumer. The right to producing wines with an appellation of origin is guaranteed by the Ministry of Agriculture, based on proposals made by the National Office of Vine and Wine (starting with the 1993 vintage year). The Ministry of Agriculture, the National Office for Vine and Wine, and the National Research Institute grants the authentication of the wines with appellation of origin. The present paper emphasize the isotopic analysis for 18O/16O and 13C/12C from wines, using a new generation Isotope Ratio MS, CF-IRMS Delta V Plus, coupled with three flexible continuous flow preparation devices (GasBench II and TC Elemental Analyser). (authors)

  1. (18)O(2) label mechanism of sulfur generation and characterization in properties over mesoporous Sm-based sorbents for hot coal gas desulfurization.

    Science.gov (United States)

    Liu, B S; Wan, Z Y; Wang, F; Zhan, Y P; Tian, M; Cheung, A S C

    2014-02-28

    Using a sol-gel method, SmMeOx/MCM-41 or SBA-15 (Me=Fe, Co and Zn) and corresponding unsupported sorbents were prepared. The desulfurization performance of these sorbents was evaluated over a fixed-bed reactor and the effects of reaction temperature, feed and sorbent composition on desulfurization performance were studied. Samarium-based sorbents used to remove H2S from hot coal gas were reported for the first time. The results of successive sulfidation/regeneration cycles revealed that SmFeO3/SBA-15 sorbent was suitable for desulfurization of hot coal gas in the chemical industry. The formation of elemental sulfur during both sulfidation and regeneration processes depended strongly on the catalytic action of Sm2O2S species, which was confirmed for the first time via high sensitive time of flight mass spectrometer (TOF-MS) using 6%vol(18)O2/Ar regeneration gas and can reduce markedly procedural complexity. The sorbents were characterized using N2-adsorption, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), temperature-programmed reduction of H2 (H2-TPR), thermogravimetry (TG) and time-of-flight mass spectrometry (TOF-MS) techniques. PMID:24462892

  2. Understanding the groundwater dynamics in the Southern Rift Valley Lakes Basin (Ethiopia). Multivariate statistical analysis method, oxygen (δ 18O) and deuterium (δ 2H)

    International Nuclear Information System (INIS)

    Multivariate statistical analysis is very important to classify waters of different hydrochemical groups. Statistical techniques, such as cluster analysis, can provide a powerful tool for analyzing water chemistry data. This method is used to test water quality data and determine if samples can be grouped into distinct populations that may be significant in the geologic context, as well as from a statistical point of view. Multivariate statistical analysis method is applied to the geochemical data in combination with δ 18O and δ 2H isotopes with the objective to understand the dynamics of groundwater using hierarchical clustering and isotope analyses. The geochemical and isotope data of the central and southern rift valley lakes have been collected and analyzed from different works. Isotope analysis shows that most springs and boreholes are recharged by July and August rainfalls. The different hydrochemical groups that resulted from the multivariate analysis are described and correlated with the geology of the area and whether it has any interaction with a system or not. (author)

  3. Inferring surface water equilibrium calcite δ18O during the last deglacial period from benthic foraminiferal records: Implications for ocean circulation

    Science.gov (United States)

    Amrhein, Daniel E.; Gebbie, Geoffrey; Marchal, Olivier; Wunsch, Carl

    2015-11-01

    The ocean circulation modifies mixed layer (ML) tracer signals as they are communicated to the deep ocean by advection and mixing. We develop and apply a procedure for using tracer signals observed "upstream" (by planktonic foraminifera) and "downstream" (by benthic foraminifera) to constrain how tracer signals are modified by the intervening circulation and, by extension, to constrain properties of that circulation. A history of ML equilibrium calcite δ18O (δ18Oc) spanning the last deglaciation is inferred from a least-squares fit of eight benthic foraminiferal δ18Oc records to Green's function estimated for the modern ocean circulation. Disagreements between this history and the ML history implied by planktonic records would indicate deviations from the modern circulation. No deviations are diagnosed because the two estimates of ML δ18Oc agree within their uncertainties, but we suggest data collection and modeling procedures useful for inferring circulation changes in future studies. Uncertainties of benthic-derived ML δ18Oc are lowest in the high-latitude regions chiefly responsible for ventilating the deep ocean; additional high-resolution planktonic records constraining these regions are of particular utility. Benthic records from the Southern Ocean, where data are sparse, appear to have the most power to reduce uncertainties in benthic-derived ML δ18Oc. Understanding the spatiotemporal covariance of deglacial ML δ18Oc will also improve abilities of δ18Oc records to constrain deglacial circulation.

  4. Validation of the doubly-labeled water (H/sup 3/H/sup 18/O) method for measuring water flux and energy metabolism in tenebrionid beetles

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, P.D.

    1981-01-01

    Doubly-labeled water (H/sup 3/H/sup 18/O) has been used to determine water flux and energy metabolism in a variety of vertebrates. This study examines the applicability of this technique to arthropods. The theory of the technique depends upon the assumption that doubly-labeled water introduced into the animal's body water equilibrates with water and carbon dioxide by the action of carbonic anhydrase. Tritium (/sup 3/H) is lost from the animal only with water while oxygen-18 is lost with both water and carbon dioxide. The difference bwtween the rates of loss of the two isotopes is proportional to CO/sub 2/ loss rate. Validation of the use of tritiated water for measuring water flux was accomplished by comparing gravimetric measurements of water gain with flux rates determined by loss of tritiated water. At room humidity, an overestimate for influx calculated from labeled water calculations was found, averaging 12 mg H/sub 2/O (g.d)/sup -1/. Comparison of CO/sub 2/ loss rate determined isotopically with rates of CO/sub 2/ loss determined by standard metabolic rates also yielded overestimates for the isotopic technique, overestimates ranging between 20 and 30%. The relevance of this for studies using labeled water for studying water fluxes and free metabolism of free-ranging arthropods is discussed.

  5. Assessing sources of nitrate contamination in the Shiraz urban aquifer (Iran) using the δ(15)N and δ(18)O dual-isotope approach.

    Science.gov (United States)

    Amiri, Haleh; Zare, Mohammad; Widory, David

    2015-01-01

    Nitrate ([Formula: see text]) is one of the major threats to the quality of the drinking water taken from the Shiraz aquifer. This aquifer undergoes high anthropogenic pressures from multiple local urban (including uncontrolled sewage systems), agricultural and industrial activities, resulting in [Formula: see text] concentrations as high as 149 mg L(-1), well above the 50 mg L(-1) guideline defined by the World Health Organisation. We coupled here classical chemical and dual isotope (δ(15)N and δ(18)O of [Formula: see text]) approaches trying to characterize sources and potential processes controlling the budget of this pollutant. Chemical data indicate that nitrate in this aquifer is explained by distinct end-members: while mineral fertilizers isotopically show to have no impact, our isotope approach identifies natural soil nitrification and organic [Formula: see text] (manure and/or septic waste) as the two main contributors. Isotope data suggest that natural denitrification may occur within the aquifer, but this conclusion is not supported by the study of other chemical parameters. PMID:25941866

  6. Recoil-range studies of heavy products of multinucleon transfer from /sup 18/O to /sup 245/Cm and /sup 249/Cf

    Energy Technology Data Exchange (ETDEWEB)

    McFarland, R.M.

    1982-09-01

    Recoil range distributions were measured for alpha and spontaneous fission activities made in the bombardment of /sup 245/Cm and /sup 249/Cf with /sup 18/O from 6.20 MeV/nucleon down to the interaction barrier. The shape of the distributions indicates tht transfers of up to four protons take place via a combination of quasi-elastic (QET) and deep inelastic (DIT) mechanisms, rather than complete fusion-de-excitation (CF) or massive transfer (MT). Angular distributions constructed from recoil range distributions, assuming QET/DIT, indicate that the QET component contributes more significantly to the heavy product residue cross section than the DIT, even though primary cross sections are expected to be higher for DIT than for QET. This may be explained qualitatively as a result of the high excitation energies associated with DIT; the very negative Q/sub gg/ of projectile stripping for these systems combined with the lower expected optimal Q/sub rxn/ of QET compared to DIT can give QET products comparatively low excitation.

  7. Spatial gradients of temperature, accumulation and δ18O-ice in Greenland over a series of Dansgaard-Oeschger events

    Directory of Open Access Journals (Sweden)

    P. Martinerie

    2012-10-01

    Full Text Available Air and water stable isotope measurements from three Greenland deep ice cores (GISP2, NGRIP and NEEM are investigated over a series of Dansgaard-Oeschger events (DO 8-9-10 which are representative of glacial millennial scale variability. Combined with firn modeling, air isotope data allow to quantify abrupt temperature increases for each drill site. Our data show that the magnitude of stadial-interstadial temperature increase is up to 3 °C larger in Central and North Greenland than in North West Greenland. The temporal water isotope (δ18O – temperature relationship varies between 0.3 and 0.6 ± 0.08‰ °C−1 and is systematically larger at NEEM, possibly due to limited changes in precipitation seasonality compared to GISP2 or NGRIP. The gas age-ice age difference of warming events represented in water and air isotopes can only be modeled when assuming a 26% (NGRIP to 34% (NEEM lower accumulation than derived from a Dansgaard-Johnsen ice flow model.

  8. The use of δ(2)H and δ(18)O isotopic analyses combined with chemometrics as a traceability tool for the geographical origin of bell peppers.

    Science.gov (United States)

    de Rijke, E; Schoorl, J C; Cerli, C; Vonhof, H B; Verdegaal, S J A; Vivó-Truyols, G; Lopatka, M; Dekter, R; Bakker, D; Sjerps, M J; Ebskamp, M; de Koster, C G

    2016-08-01

    Two approaches were investigated to discriminate between bell peppers of different geographic origins. Firstly, δ(18)O fruit water and corresponding source water were analyzed and correlated to the regional GNIP (Global Network of Isotopes in Precipitation) values. The water and GNIP data showed good correlation with the pepper data, with constant isotope fractionation of about -4. Secondly, compound-specific stable hydrogen isotope data was used for classification. Using n-alkane fingerprinting data, both linear discriminant analysis (LDA) and a likelihood-based classification, using the kernel-density smoothed data, were developed to discriminate between peppers from different origins. Both methods were evaluated using the δ(2)H values and n-alkanes relative composition as variables. Misclassification rates were calculated using a Monte-Carlo 5-fold cross-validation procedure. Comparable overall classification performance was achieved, however, the two methods showed sensitivity to different samples. The combined values of δ(2)H IRMS, and complimentary information regarding the relative abundance of four main alkanes in bell pepper fruit water, has proven effective for geographic origin discrimination. Evaluation of the rarity of observing particular ranges for these characteristics could be used to make quantitative assertions regarding geographic origin of bell peppers and, therefore, have a role in verifying compliance with labeling of geographical origin. PMID:26988484

  9. Sauna, sweat and science - quantifying the proportion of condensation water versus sweat using a stable water isotope ((2)H/(1)H and (18)O/(16)O) tracer experiment.

    Science.gov (United States)

    Zech, Michael; Bösel, Stefanie; Tuthorn, Mario; Benesch, Marianne; Dubbert, Maren; Cuntz, Matthias; Glaser, Bruno

    2015-01-01

    Most visitors of a sauna appreciate the heat pulse that is perceived when water is poured on the stones of a sauna stove. However, probably only few bathers are aware that this pleasant heat pulse is caused by latent heat being released onto our skin due to condensation of water vapour. In order to quantify the proportion of condensation water versus sweat to dripping water of test persons we conducted sauna experiments using isotopically labelled (δ(18)O and δ(2)H) thrown water as tracer. This allows differentiating between 'pure sweat' and 'condensation water'. Two ways of isotope mass balance calculations were applied and yielded similar results for both water isotopes. Accordingly, condensation contributed considerably to dripping water with mean proportions of 52 ± 12 and 54 ± 7% in a sauna experiment in winter semester 2011/12 and 30 ± 13 and 33 ± 6% in a sauna experiment in winter semester 2012/13, respectively, depending on the way of calculating the isotope mass balance. It can be concluded from the results of our dual isotope labelling sauna experiment that it is not all about sweat in the sauna.

  10. Preliminary insights into δ15N and δ18O of nitrate in natural mosses: a new application of the denitrifier method.

    Science.gov (United States)

    Liu, Xue-Yan; Koba, Keisuke; Takebayashi, Yu; Liu, Cong-Qiang; Fang, Yun-Ting; Yoh, Muneoki

    2012-03-01

    Natural mosses have been employed as reactive and accumulative indicators of atmospheric pollutants. Using the denitrifier method, the concentration, δ(15)N and δ(18)O of moss nitrate (NO(3)(-)) were measured to elucidate the sources of NO(3)(-) trapped in natural mosses. Oven drying at 55-70 °C, not lyophilization, was recommended to dry mosses for NO(3)(-) analyses. An investigation from urban to mountain sites in western Tokyo suggested that moss [NO(3)(-)] can respond to NO(3)(-) availability in different habitats. NO(3)(-) in terricolous mosses showed isotopic ratios as close to those of soil NO(3)(-), reflecting the utilization of soil NO(3)(-). Isotopic signatures of NO(3)(-) in corticolous and epilithic mosses elucidated atmospheric NO(3)(-) sources and strength from the urban (vehicle NO(x) emission) to mountain area (wet-deposition NO(3)(-)). However, mechanisms and isotopic effects of moss NO(3)(-) utilization must be further verified to enable the application of moss NO(3)(-) isotopes for source identification.

  11. Validation of the doubly-labeled water (H3H18O) method for measuring water flux and energy metabolism in tenebrionid beetles

    International Nuclear Information System (INIS)

    Doubly-labeled water (H3H18O) has been used to determine water flux and energy metabolism in a variety of vertebrates. This study examines the applicability of this technique to arthropods. The theory of the technique depends upon the assumption that doubly-labeled water introduced into the animal's body water equilibrates with water and carbon dioxide by the action of carbonic anhydrase. Tritium (3H) is lost from the animal only with water while oxygen-18 is lost with both water and carbon dioxide. The difference bwtween the rates of loss of the two isotopes is proportional to CO2 loss rate. Validation of the use of tritiated water for measuring water flux was accomplished by comparing gravimetric measurements of water gain with flux rates determined by loss of tritiated water. At room humidity, an overestimate for influx calculated from labeled water calculations was found, averaging 12 mg H2O (g.d)-1. Comparison of CO2 loss rate determined isotopically with rates of CO2 loss determined by standard metabolic rates also yielded overestimates for the isotopic technique, overestimates ranging between 20 and 30%. The relevance of this for studies using labeled water for studying water fluxes and free metabolism of free-ranging arthropods is discussed

  12. 钒掺杂W18O49纳米线的室温p型电导与NO2敏感性能%P-type conductivity and NO2 sensing properties for V-doped W18O49 nanowires at room temperature

    Institute of Scientific and Technical Information of China (English)

    秦玉香; 刘凯轩; 刘长雨; 孙学斌

    2013-01-01

    钨氧化物纳米线在高灵敏度低功耗气体传感器中极具应用潜力,且通过掺杂改性可进一步显著改善其敏感性能。本文以WCl6为钨源, NH4VO3为掺杂剂,采用溶剂热法合成了钒掺杂的W18O49纳米线。利用扫描电镜、透射电镜、X射线衍射、X射线光电子能谱仪表征了纳米线的微结构,并利用静态气敏性能测试系统评价了掺杂纳米线的NO2敏感性能。研究结果表明:五价钒离子受主掺杂进入氧化钨晶格结构,抑制了纳米线沿轴向的生长并导致了纳米线束的二次集聚;室温下,钒掺杂W18O49纳米线接触NO2气体后表现出反常的p型响应特性;随工作温度逐渐升高至约110◦C时,发生从p型到n型的电导特性转变;该掺杂纳米线气敏元件对浓度低至80 ppb (1 ppb=10−9)的NO2气体具有明显的室温敏感响应和良好的响应稳定性。分析并探讨了钒掺杂W18 O49纳米线的高室温敏感特性及其p-n电导转型机理,认为钒掺杂W18 O49纳米线在室温下的良好敏感响应及反常p型导电性与掺杂纳米线表面高密度非稳表面态诱导的低温气体强吸附有关。%Tungsten oxide nanowire has a great potential application to gas sensor with high sensitivity and low power consumption. Its gas-sensing properties can be greatly improved after doping the nanowires. In this paper, vanadium (V)-doped W18O49 nanowires are synthesized by solvothermal method, with WCl6 serving as precursor and NH4VO3 as dopant. The microstructures of the pure and the doped nanowires are characterized by using SEM, TEM, XRD, and XPS techniques, and the NO2-sensing properties are evaluated in a static gas-sensing measurement system. The obtained results indicate that the introduction of V dopant suppresses the growth of one-dimensional nanowires along their axis direction and causes the secondary assembly of nanowires bundles. At room temperature, the V-doped W18O49 nanowires show

  13. Microwave dielectric properties of Ba_(6-3x)La_(8+2x)(Ti_(1-z)Zr_z)_(18)O_(54)(x=2/3) ceramics

    Institute of Scientific and Technical Information of China (English)

    高旭芳; 丘泰

    2010-01-01

    Zr substitution for Ti was investigated to modify the dielectric properties of Ba6-3xLa8+2xTi18O54(x=2/3) ceramics.A single-phase solid solution with tungstenbronze-like structure was formed in the range of 0

  14. Determination of the H-2/H-1, O-17/O-16, and O-18/O-16 isotope ratios in water by means of tunable diode laser spectroscopy at 1.39 mu m

    NARCIS (Netherlands)

    Kerstel, E.R.Th.; Gagliardi, G.; Gianfrani, L.; Meijer, H.A.J.; van Trigt, R.; Ramaker, R.

    2002-01-01

    We demonstrate the feasibility of the accurate and simultaneous measurement of the H-2/H-1, O-17/O-16, and O-18/O-16 isotope ratios in water vapor by means of tunable diode laser spectroscopy. The absorptions are due to the nu(1) + nu(3) combination band, observed using a room temperature, distribut

  15. δ18O water isotope in the iLOVECLIM model (version 1.0 – Part 3: A paleoperspective based on present-day data-model comparison for oxygen stable isotopes in carbonates

    Directory of Open Access Journals (Sweden)

    T. Caley

    2013-03-01

    Full Text Available Oxygen stable isotopes (18O are among the most usual tools in paleoclimatology/paleoceanography. Simulation of oxygen stable isotopes allows testing how the past variability of these isotopes in water can be interpreted. By modelling the proxy directly in the model, the results can also be directly compared with the data. Water isotopes have been implemented in the global three-dimensional model of intermediate complexity iLOVECLIM allowing fully coupled atmosphere-ocean simulations. In this study, we present the validation of the model results for present day climate against global database for oxygen stable isotopes in carbonates. The limitation of the model together with the processes operating in the natural environment reveal the complexity of use the continental calcite 18O signal of speleothems for a data-model comparison exercise. On the contrary, the reconstructed surface ocean calcite δ18O signal in iLOVECLIM does show a very good agreement with late Holocene database (foraminifers at the global and regional scales. Our results indicate that temperature and the isotopic composition of the seawater are the main control on the fossil δ18O signal recorded in foraminifer shells and that depth habitat and seasonality play a role but have secondary importance. We argue that a data-model comparison for surface ocean calcite δ18O in past climate, such as the last glacial maximum (≈21 000 yr, could constitute an interesting tool for mapping the potential shifts of the frontal systems and circulation changes throughout time. Similarly, the potential changes in intermediate oceanic circulation systems in the past could be documented by a data (benthic foraminifers-model comparison exercise whereas future investigations are necessary in order to quantitatively compare the results with data for the deep ocean.

  16. δ18O water isotope in the iLOVECLIM model (version 1.0 – Part 3: A palaeo-perspective based on present-day data–model comparison for oxygen stable isotopes in carbonates

    Directory of Open Access Journals (Sweden)

    T. Caley

    2013-09-01

    Full Text Available Oxygen stable isotopes (δ18O are among the most useful tools in palaeoclimatology/palaeoceanography. Simulation of oxygen stable isotopes allows testing how the past variability of these isotopes in water can be interpreted. By modelling the proxy directly in the model, the results can also be directly compared with the data. Water isotopes have been implemented in the global three-dimensional model of intermediate complexity iLOVECLIM, allowing fully coupled atmosphere–ocean simulations. In this study, we present the validation of the model results for present-day climate against the global database for oxygen stable isotopes in carbonates. The limitation of the model together with the processes operating in the natural environment reveal the complexity of use the continental calcite-δ18O signal of speleothems for a global quantitative data–model comparison exercise. On the contrary, the reconstructed surface ocean calcite-δ18O signal in iLOVECLIM does show a very good agreement with the late Holocene database (foraminifers at the global and regional scales. Our results indicate that temperature and the isotopic composition of the seawater are the main control on the fossil-δ18O signal recorded in foraminifer shells when all species are grouped together. Depth habitat, seasonality and other ecological effects play a more significant role when individual species are considered. We argue that a data–model comparison for surface ocean calcite δ18O in past climates, such as the Last Glacial Maximum (≈ 21 000 yr, could constitute an interesting tool for mapping the potential shifts of the frontal systems and circulation changes throughout time. Similarly, the potential changes in intermediate oceanic circulation systems in the past could be documented by a data (benthic foraminifers-model comparison exercise whereas future investigations are necessary in order to quantitatively compare the results with data for the deep ocean.

  17. Magnetic and Mössbauer spectroscopy studies of NiAl{sub 0.2}Fe{sub 1.8}O{sub 4}/SiO{sub 2} nanocomposites synthesized by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiaming [Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000 (China); School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Wang, Li [Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000 (China); College of Physics, Jilin University, Changchun 130012 (China); Bai, Zhaohui [School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Li, Ji [Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000 (China); Lu, Jingbin [College of Physics, Jilin University, Changchun 130012 (China); Li, Haibo, E-mail: lihaibo@jlnu.edu.cn [Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000 (China)

    2014-03-15

    The structural and magnetic properties of NiAl{sub 0.2}Fe{sub 1.8}O{sub 4}/SiO{sub 2} nanocomposites prepared with the sol–gel method were studied by using X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer, and Mössbauer spectroscopy. The average grain size of NiAl{sub 0.2}Fe{sub 1.8}O{sub 4} in the nanocomposites was found to increase from 5 to 37 nm with increasing the annealing temperature from 800 to 1200 °C while the lattice constant was almost kept a constant of ∼0.833 nm. The saturation magnetization of the nanocomposites was shown to increase with increasing the grain size. The thickness of the dead layer on the surface of the ferrite grain was obtained to about (0.61±0.02) nm. The Mössbauer spectra indicated the evolution of magnetic properties of NiAl{sub 0.2}Fe{sub 1.8}O{sub 4} nanoparticles in the nanocomposites from superparamagnetic to magnetically ordered character with increasing the size of nanoparticles. - Highlights: • The grain size 5–37 nm of NiAl{sub 0.2}Fe{sub 1.8}O{sub 4} in NiAl{sub 0.2}Fe{sub 1.8}O{sub 4}/SiO{sub 2} nanocomposites were prepared. • The thickness of magnetically dead layer on the surface of ferrite grain was calculated. • The amount of Fe{sup 3+} on the surface of grains decreased with increasing annealing temperature.

  18. Modelling (18)O2 and (16)O2 unidirectional fluxes in plants. III: fitting of experimental data by a simple model.

    Science.gov (United States)

    André, Marcel J

    2013-08-01

    Photosynthetic assimilation of CO2 in plants results in the balance between the photochemical energy developed by light in chloroplasts, and the consumption of that energy by the oxygenation processes, mainly the photorespiration in C3 plants. The analysis of classical biological models shows the difficulties to bring to fore the oxygenation rate due to the photorespiration pathway. As for other parameters, the most important key point is the estimation of the electron transport rate (ETR or J), i.e. the flux of biochemical energy, which is shared between the reductive and oxidative cycles of carbon. The only reliable method to quantify the linear electron flux responsible for the production of reductive energy is to directly measure the O2 evolution by (18)O2 labelling and mass spectrometry. The hypothesis that the respective rates of reductive and oxidative cycles of carbon are only determined by the kinetic parameters of Rubisco, the respective concentrations of CO2 and O2 at the Rubisco site and the available electron transport rate, ultimately leads to propose new expressions of biochemical model equations. The modelling of (18)O2 and (16)O2 unidirectional fluxes in plants shows that a simple model can fit the photosynthetic and photorespiration exchanges for a wide range of environmental conditions. Its originality is to express the carboxylation and the oxygenation as a function of external gas concentrations, by the definition of a plant specificity factor Sp that mimics the internal reactions of Rubisco in plants. The difference between the specificity factors of plant (Sp) and of Rubisco (Sr) is directly related to the conductance values to CO2 transfer between the atmosphere and the Rubisco site. This clearly illustrates that the values and the variation of conductance are much more important, in higher C3 plants, than the small variations of the Rubisco specificity factor. The simple model systematically expresses the reciprocal variations of

  19. The effect of drought and interspecific interactions on depth of water uptake in deep- and shallow-rooting grassland species as determined by δ18O natural abundance

    Science.gov (United States)

    Hoekstra, N. J.; Finn, J. A.; Hofer, D.; Lüscher, A.

    2014-08-01

    Increased incidence of drought, as predicted under climate change, has the potential to negatively affect grassland production. Compared to monocultures, vertical belowground niche complementarity between shallow- and deep-rooting species may be an important mechanism resulting in higher yields and higher resistance to drought in grassland mixtures. However, very little is known about the belowground responses in grassland systems and increased insight into these processes may yield important information both to predict the effect of future climate change and better design agricultural systems to cope with this. This study assessed the effect of a 9-week experimental summer drought on the depth of water uptake of two shallow-rooting species (Lolium perenne L. and Trifolium repens L.) and two deep-rooting species (Cichorium intybus L. and Trifolium pratense L.) in grassland monocultures and four-species mixtures by using the natural abundance δ18O isotope method. We tested the following three hypotheses: (1) drought results in a shift of water uptake to deeper soil layers, (2) deep-rooting species take up a higher proportion of water from deeper soil layers relative to shallow-rooting species, and (3) as a result of interspecific interactions in mixtures, the water uptake of shallow-rooting species becomes shallower when grown together with deep-rooting species and vice versa, resulting in reduced niche overlap. The natural abundance δ18O technique provided novel insights into the depth of water uptake of deep- and shallow- rooting grassland species and revealed large shifts in depth of water uptake in response to drought and interspecific interactions. Compared to control conditions, drought reduced the proportional water uptake from 0-10 cm soil depth (PCWU0-10) of L. perenne, T. repens and C. intybus in monocultures by on average 54%. In contrast, the PCWU0-10 of T. pratense in monoculture increased by 44%, and only when grown in mixture did the PCWU0-10 of T

  20. Plasma Proteome Response to Severe Burn Injury Revealed by 18O-Labeled “Universal” Reference-based Quantitative Proteomics

    Science.gov (United States)

    Qian, Wei-Jun; Petritis, Brianne O.; Kaushal, Amit; Finnerty, Celeste C; Jeschke, Marc G; Monroe, Matthew E.; Moore, Ronald J.; Schepmoes, Athena A.; Xiao, Wenzhong; Moldawer, Lyle L.; Davis, Ronald W.; Tompkins, Ronald G.; Herndon, David N.; Camp, David G.; Smith, Richard D.

    2010-01-01

    A burn injury represents one of the most severe forms of human trauma and is responsible for significant mortality worldwide. Here, we present the first quantitative proteomics investigation of the blood plasma proteome response to severe burn injury by comparing the plasma protein concentrations of 10 healthy control subjects with those of 15 severe burn patients at two time-points following the injury. The overall analytical strategy for this work integrated immunoaffinity depletion of the 12 most abundant plasma proteins with cysteinyl-peptide enrichment-based fractionation prior to LC-MS analyses of individual patient samples. Incorporation of an 18O-labeled “universal” reference among the sample sets enabled precise relative quantification across samples. In total, 313 plasma proteins confidently identified with two or more unique peptides were quantified. Following statistical analysis, 110 proteins exhibited significant abundance changes in response to the burn injury. The observed changes in protein concentrations suggest significant inflammatory and hypermetabolic response to the injury, which is supported by the fact that many of the identified proteins are associated with acute phase response signaling, the complement system, and coagulation system pathways. The regulation of ~35 proteins observed in this study is in agreement with previous results reported for inflammatory or burn response, but approximately 50 potentially novel proteins previously not known to be associated with burn response or inflammation are also found. Elucidating proteins involved in the response to severe burn injury may reveal novel targets for therapeutic interventions, as well as potential predictive biomarkers for patient outcomes such as multiple organ failure. PMID:20698492

  1. Morphology and kinematics of the gas envelope of protostar L1527 as obtained from ALMA observations of the C18O(2-1) line emission

    Science.gov (United States)

    Tuan-Anh, P.; Nhung, P. T.; Hoai, D. T.; Diep, P. N.; Phuong, N. T.; Thao, N. T.; Darriulat, P.

    2016-09-01

    Using ALMA observations of the C18O(2-1) line emission of the gas envelope of protostar L1527, we have reconstructed its morphology and kinematics under the assumption of axisymmetry about the west-east axis. The main original contribution to our understanding of the formation process of L1527 is the presentation of a simple 3D parameterisation based solely on regions that are not dominated by absorption. In the explored range (˜0.7 to 5 arcsec from the star) the model reproduces observations better than earlier attempts. The main results include: a measurement of the rotation velocity that confirms its evolution to Keplerian toward short distances; a measurement of the mean in-fall velocity, 0.43±0.10 km s-1, lower than free fall velocity, with no evidence for the significant r-dependence suggested by an earlier analysis; a measurement of the central mass, 0.23±0.06 M⊙ within a distance of 1.5 arcsec from the star, in agreement with earlier estimates obtained from a different range of distances; evidence for a strong disc plane depression of the in-falling flux resulting in an X shaped flow possibly caused by the freeze-out of CO molecules on dust grains; a measurement of the accretion rate, 3.5±1.0 10-7M⊙ yr-1at a distance of 1 arcsec (140 au) from the star; evidence for a 10° tilt of the symmetry plane of the envelope about the line of sight, cancelling below ˜3 arcsec from the star, but matching infrared observations and being also apparent on the sky map of the mean Doppler velocity.

  2. A conifer-friendly high-throughput α-cellulose extraction method for δ13C and δ18O stable isotope ratio analysis

    Science.gov (United States)

    Lin, W.; Noormets, A.; domec, J.; King, J. S.; Sun, G.; McNulty, S.

    2012-12-01

    Wood stable isotope ratios (δ13C and δ18O) offer insight to water source and plant water use efficiency (WUE), which in turn provide a glimpse to potential plant responses to changing climate, particularly rainfall patterns. The synthetic pathways of cell wall deposition in wood rings differ in their discrimination ratios between the light and heavy isotopes, and α-cellulose is broadly seen as the best indicator of plant water status due to its local and temporal fixation and to its high abundance within the wood. To use the effects of recent severe droughts on the WUE of loblolly pine (Pinus taeda) throughout Southeastern USA as a harbinger of future changes, an effort has been undertaken to sample the entire range of the species and to sample the isotopic composition in a consistent manner. To be able to accommodate the large number of samples required by this analysis, we have developed a new high-throughput method for α-cellulose extraction, which is the rate-limiting step in such an endeavor. Although an entire family of methods has been developed and perform well, their throughput in a typical research lab setting is limited to 16-75 samples per week with intensive labor input. The resin exclusion step in conifersis is particularly time-consuming. We have combined the recent advances of α-cellulose extraction in plant ecology and wood science, including a high-throughput extraction device developed in the Potsdam Dendro Lab and a simple chemical-based resin exclusion method. By transferring the entire extraction process to a multiport-based system allows throughputs of up to several hundred samples in two weeks, while minimizing labor requirements to 2-3 days per batch of samples.

  3. Tree ring δ18O's indication of a shift to a wetter climate since the 1880s in the western Tianshan Mountains of northwestern China

    Science.gov (United States)

    Xu, Guobao; Liu, Xiaohong; Wu, Guoju; Chen, Tuo; Wang, Wenzhi; Zhang, Qiong; Zhang, Youfu; Zeng, Xiaomin; Qin, Dahe; Sun, Weizhen; Zhang, Xuanwen

    2015-07-01

    Central Asian droughts have drastically and significantly affected agriculture and water resource management in these arid and semiarid areas. Based on tree ring δ18O from native, dominant Schrenk spruce (Picea schrenkiana Fisch. et Mey.), we developed a 300 year (1710-2010) standard precipitation-evaporation index (SPEI) reconstruction from January to August for China's western Tianshan Mountains. The regression model explained 37.6% of the variation in the SPEI reconstruction during the calibration period from 1950 to 2010. Comparison with previous drought reconstructions confirmed the robustness of our reconstruction. The 20th century has been a relatively wet period during the past 300 years. The SPEI showed quasi 2, 5, and 10 year cycles. Several pluvials and droughts with covariability over large areas were revealed clearly in the reconstruction. The two longest pluvials (lasting for 12 years), separated by 50 years, appeared in the 1900s and the 1960s. The most severe drought occurred from 1739 to 1761 and from 1886 to 1911 was the wettest period since 1710. Compared to previous investigations of hydroclimatic changes in the western Tianshan Mountains, our reconstruction revealed more low-frequency variability and indicated that climate in the western Tianshan Mountains shifted from dry to wet in 1886. This regime shift was generally consistent with other moisture reconstructions for the northeastern Tibetan Plateau and northern Pakistan and may have resulted from a strengthened westerly circulation. The opposite hydrological trends in the western Tianshan Mountains and southeastern Tibetan Plateau reveal a substantial influence of strengthened westerlies and weakening of the Indian summer monsoon.

  4. Measuring fast variations of δ^{18}O and δ^2H in atmospheric water vapour using laser spectroscopy: an instrument inter-comparison and characterisation study

    Science.gov (United States)

    Aemisegger, F.; Sturm, P.; Graf, P.; Sodemann, H.; Pfahl, S.; Knohl, A.; Wernli, H.

    2012-04-01

    Fast variations of stable water isotopes in water vapour have become measurable lately using novel laser spectroscopic techniques. This allows us to perform process-based investigations of the atmospheric water cycle at the time scales of significant weather events. An important prerequisite for such studies implying automatic field measurements lasting for several weeks or even months is a detailed knowledge about sources of uncertainty and instrument properties. We present a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro) and off-axis integrated cavity output spectroscopy (Los Gatos Resarch). The old versions (L1115-i, WVIA) and the new versions (L2130-i, WVIA-EP) of both systems were tested. The uncertainty components of the measurements were assessed in laboratory experiments, focussing on effects of (i) water vapour mixing ratio, (ii) measurement stability, (iii) uncertainties due to calibration and (iv) response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Knowledge from our laboratory experiments was used to s