WorldWideScience

Sample records for 18o 24mg 44ca

  1. High Spin States in ^24Mg

    Science.gov (United States)

    Schwartz, J.; Lister, C. J.; Wuosmaa, A.; Betts, R. R.; Blumenthal, D.; Carpenter, M. P.; Davids, C. N.; Fischer, S. M.; Hackman, G.; Janssens, R. V. F.

    1996-05-01

    The ^12C(^16O,α)^24Mg reaction was used at 51.5MeV to populate high angular momentum states in ^24Mg. Gamma-rays de-exciting high spin states were detected in a 20 detector spectrometer (the AYE-ball) triggered by the ANL Fragment Mass Analyser (FMA). Channel selection, through detection of ^24Mg nuclei with the appropriate time of flight, was excellent. All the known decays from high spin states were seen in a few hours, with the exception of the 5.04 MeV γ-decay of the J^π=9^- state at 16.904 MeV footnote A.E.Smith et al., Phys. Lett. \\underlineB176, (1986)292. which could not be confirmed. The potential of the technique for studying the radiative decay of states with very high spin in light nuclei will be discussed.

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

    Directory of Open Access Journals (Sweden)

    Cinausero M.

    2012-02-01

    Full Text Available In the framework of studying clustering effects in N=Z light nuclei, an experiment was carried out to get information on the properties of the 48Cr composite nuclei produced via the 24Mg +24Mg reaction. In particular, the study regards the 48Cr at 60 MeV of excitation energy where a resonance with a narrow width (170 KeV has been found by measuring the elastic and anelastic channels. To determine the deformation of this state, evaporative Light Charged Particles (LCP are measured and compared to the Statistical Model (SM predictions, which are very sensitive to nuclear deformation. The experiment was performed at LNL using the 8ĒLP apparatus to select LCPs and a Parallel Plate Avalanche Counter (PPAC system to detect the Evaporation Residues (ER. Preliminary results on the measurements of ER – LCP and LCP – LCP angular correlations are presented which indicate the presence of a very large deformation.The analysis will proceed with the extraction of the LCP energy spectra and with the angular correlations for high multiplicity channels to determine the deformation.

  3. 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%.

  4. 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.

  5. Multiplicity characteristics in relativistic 24Mg-nucleus collisions

    Institute of Scientific and Technical Information of China (English)

    A.Abdelsalam; E.A.Shaat; Z.Abou-Moussa; B.M.Badawy; Z.S.Mater

    2013-01-01

    This work is concerned with the analyses of the shower and gray particle production in 4.5 A GeV/c 24Mg collision with emulsion nuclei.The highest particle production occurs in the region of the low impact parameters.While the multiplicity of the shower particles emitted in the forward direction depends on the projectile mass number and energy,the multiplicity of the backward ones shows a limiting behaviour.The source of the emission of the forward shower particles is completely different from that of the backward ones.The target fragments are produced in a thermalized system of emission.

  6. Search for $^{12}$C+$^{12}$C clustering in $^{24}$Mg ground state

    Indian Academy of Sciences (India)

    B N JOSHI; ARUN K JAIN; D C BISWAS; B V JOHN; Y K GUPTA; L S DANU; R P VIND; G K PRAJAPATI; S MUKHOPADHYAY; A SAXENA

    2017-02-01

    In the backdrop of many models, the heavy cluster structure of the ground state of $^{24}$Mg has been probed experimentally for the first time using the heavy cluster knockout reaction $^{24}$Mg($^{12}$C, $^{212}$C)$^{12}$C in thequasifree scattering kinematic domain. In the ($^{12}$C, $^{212}$C) reaction, the direct $^{12}$C-knockout cross-section was found to be very small. Finite-range knockout theory predictions were much larger for ($^{12}$C, 212C) reaction,indicating a very small $^{12}$C−$^{12}$C clustering in $^{24}$Mg(g.s.). Our present results contradict most of the proposed heavy cluster ($^{12}$C+$^{12}$C) structure models for the ground state of $^{24}$Mg.

  7. Spin decomposition of the responses of sup 44 Ca and sup 48 Ca to 300 MeV protons

    Energy Technology Data Exchange (ETDEWEB)

    Baker, F.T.; Bimbot, L.; Fergerson, R.W.; Glashausser, C.; Green, A.; Haeusser, O.; Hicks, K.; Jones, K.; Miller, C.A.; Vetterli, M.; Abegg, R.; Beatty, D.; Bonin, B.; Castel, B.; Chen, X.Y.; Cupps, V.; Djalali, C.; Henderson, R.; Jackson, K.P.; Jeppesen, R.; Nakayama, K.; Nanda, S.K.; Sawafta, R.; Yen, S. (University of Georgia, Athens, Georgia 30602 (US) Institut de Physique Nucleaire, F-91406 Orsay, France Rutgers University, Piscataway, New Jersey 08854 Simon Fraser University, Burnaby, Canada V5A1S6 TRIUMF, 4004 Westbrook Mall, Vancouver, Canada V6T2A3 Los Alamos National Laboratory, Los Alamos, New Mexico 87544 Centre d' Etudes Nucleaires de Saclay, 91191 Gif sur Yvette, CEDEX, France Queen' s University, Kingston, Canada K7L3N6 University of Colorado, Boulder, Colorado 80309 University of South Carolina, Columbia, South Carolina 29208 Continuous Electron Beam Accelerator Facility, 12000 Jefferson Ave., Newport News, Virginia 23606 University of Alberta, Edmonton, Canada T6G2J1)

    1991-07-01

    Angular distributions of the double-differential cross section {ital d}{sup 2}{sigma}/{ital d}{Omega} {ital dE}({sigma}) and the spin-flip probability {ital S}{sub {ital n}{ital n}} have been measured for inclusive proton inelastic scattering from {sup 44}Ca at 290 MeV and from {sup 48}Ca at 318 MeV. Excitation energies up to about 50 MeV for {sup 44}Ca and 40 MeV for {sup 48}Ca have been investigated over the laboratory angular ranges of 3{degree} to 12{degree} for {sup 44}Ca and 3{degree} to 9{degree} for {sup 48}Ca. Multipole decompositions of angular distributions of both the spin-flip cross section {sigma}{ital S}{sub {ital n}{ital n}} and the estimated cross section for {Delta}{ital S}=0 transitions have been performed. Distributions of strengths were deduced for {Delta}{ital L}=1, {Delta}{ital S}=0 (the giant dipole), {Delta}{ital L}=2, {Delta}{ital S}=0 (the giant quadrupole), {Delta}{ital L}=0, {Delta}{ital S}=1 (the magnetic dipole), {Delta}{ital L}=1, {Delta}{ital S}=1 (the spin dipole), and {Delta}{ital L}=2, {Delta}{ital S}=1 (the spin quadrupole). The {Delta}{ital S}=0 summed strengths for {sup 44}Ca are lower than for {sup 40}Ca and {sup 48}Ca. The spin-dipole summed strengths are found to be approximately independent of {ital A}. For {sup 48}Ca, essentially all {ital M}1 strength observed was in the 10.23 MeV 1{sup +} state; for {sup 44}Ca, {ital M}1 strength was observed to be fragmented over a range of 7 to 18 Mev.

  8. $^{24}$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.

  9. δ44Ca in N. pachy (left): A Promising Tool for SST-Reconstruction in High-Latitude Oceans

    Science.gov (United States)

    Hippler, D.; Gussone, N.; Darling, K.; Eisenhauer, A.; Nagler, T. F.

    2002-12-01

    Reconstructions of sea surface temperatures (SSTs) by means of planktonic foraminifera are an essential tool in paleoceanography. Unlike to marine tropical environments where a number of established SST-proxies exist, information on paleo-SST of polar water masses is scarce. In these regions high-resolution records exist mainly for continental environments. Ca isotopes bear a high potential as SST proxies as they are insensitive to changes in global ice volume, evaporation or freshwater input. Here, measurements of the Ca-isotopic composition on calcite shells of Neogloboquadrina pachyderma (left coiling) -a dominant species in subpolar and polar surface waters- are presented. The genotype of individuals tests was determined at the University of Edinburgh. Subsequently the respective calcite shells were analysed for δ44Ca at the University of Bern. The most complete data set is from the polar North Atlantic. All samples are from the same genotype and span a temperature (T) range from 1.9°C to 6.5°C. It was found that T correlates well with δ44Ca. The total δ44Ca-variation results in a δ44Ca-change of 0.2‰ per 1°C defined by a linear regression. In order to test whether the correlation is influenced by hydrographic or genotype differences a second set of a Southern Atlantic genotype of N. pachy (left) has been investigated. Preliminary observations point to T as the main factor controlling δ44Ca variations and a T dependence very similar to that of Arctic specimen. Remarkably, this T dependence (although not the absolute values) is identical within errors to the one of tropical G. sacculifer (Nagler et al., 2000, G3). Thus, even though Ca isotope fractionation is known to be species-dependent, the increase of 0.2‰ δ44Ca per 1°C seems to reflect a particular mode of biocalcification. While more calibration work is needed, it appears that T changes of polar surface waters will be quantitatively resolvable.

  10. 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.

  11. 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.

  12. 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.)

  13. Discovery of a 6/sup -/, T=1 resonance in /sup 24/Mg via high-resolution inelastic electron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Zarek, H.; Pich, B.O.; Drake, T.E.; Rowe, D.J.; Bertozzi, W.; Creswell, C.; Hirsch, A.; Hynes, M.V.; Kowalski, S.; Norum, B.; Rad, F.N.; Sargent, C.P.; Williamson, C.F.; Lindgren, R.A.

    1977-04-04

    The unique high-resolution and high-energy features of the electron-scattering facility at the MIT-Bates Accelerator were used to locate a dominant narrow resonance at 15.045 +- 0.035 MeV in /sup 24/Mg. A spin-parity assignment of 6/sup -/ and an isospin T=1 assignment were made. The M6 form factor was measured and compared to the prediction of a theoretical calculation which uses the open-shell random-phase approximation on a shell-model ground state for /sup 24/Mg.

  14. Splitting of ISGMR strength in the light-mass nucleus 24Mg due to ground-state deformation

    Directory of Open Access Journals (Sweden)

    Y.K. Gupta

    2015-09-01

    Full Text Available The isoscalar giant monopole resonance (ISGMR strength distribution in 24Mg has been determined from background-free inelastic scattering of 386-MeV α particles at extreme forward angles, including 0∘. 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 24Mg.

  15. Elastic and inelastic scattering of 0. 8 GeV polarized protons from /sup 24/Mg and /sup 26/Mg

    Energy Technology Data Exchange (ETDEWEB)

    Blanpied, G.S.; Ritchie, B.G.; Barlett, M.L.; Hoffmann, G.W.; McGill, J.A.; Milner, E.C.; Jones, K.W.; Nanda, S.K.; de Swiniarski, R.

    1988-05-01

    Data on 800 MeV polarized proton scattering on /sup 24/Mg and /sup 26/Mg are presented. Angular distributions and analyzing power data have been extracted from fits to 26 peaks in the spectra for /sup 24/Mg and 23 peaks in /sup 26/Mg. Although there are a variety of shapes for the angular distributions, the analyzing power data for all states are positive and similar in magnitude and seem to be consistent with a two-body operator for the excitation with a spin structure much like that for the free proton-nucleon system. Evidence for a level in /sup 26/Mg at 8.03 MeV with J>4 is presented. Comparison between the observed angular distribution, coupled channels, and distorted wave Born approximation calculations, and the angular distributions of excited states in neighboring nuclei, support the assignment of J/sup ..pi../ = 5/sup -/ or 6/sup +/. Coupled channels calculations for the 0/sup +/, 2/sup +/, 4/sup +/, and 6/sup +/ members of the ground state rotational bands of /sup 24/Mg and /sup 26/Mg are compared to the data. Deformation parameters from distorted wave Born approximation calculations are determined for most of the angular distributions.

  16. Surface absorption in the {sup 32}S+{sup 24}Mg interactions at energies near the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco, J.C.; Sanchez, F.; Diaz, J.; Ferrero, J.L. [Valencia Univ. (Spain); Bilwes, B. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Ruiz, J.A. [Universidad Publica de Navarra, Pamplona (Spain); Kadi-Hanifi, D. [Universite de Blida (Algeria)

    1995-12-31

    Elastic scattering {sup 32} S on {sup 24} Mg has been measured at 65.0, 75.0, 86.3, 95.0 and 110.0 MeV-lab energies, and the data were systematically analysed with semi-phenomenological potentials. Using microscopic potentials we found similar results at the lowest incident energies, for which we have compared both the microscopic and semi-phenomenological potentials. It appears that the absorption takes place in a narrow range at the nuclear surface and is mainly due to the low lying collective surface states. (author). 41 refs., 11 figs., 4 tabs.

  17. THz and Ft-Ir Study of 18-O Isotopologues of Sulfur Dioxide: 32S16O18O and 32S18O_2

    Science.gov (United States)

    Margulès, L.; Motiyenko, R. A.; Demaison, J.; Perrin, Agnes; Kwabia Tchana, F.; Manceron, Laurent

    2016-06-01

    Sulfur dioxide is a molecule that have a great interest in different domains: for atmospheric and planetology chemistry, it is also ubiquitous and abundant in interstellar medium. If the 16O species were extensively studied, this is not the case of the 18O isotopologues. The aim of this study is first to complete the rotational spectra of the ground state with these new measurements up to 1.5 THz, previous measurements are up to 1050 GHz for the 32S16O18O species, and 145 GHz concerning the 32S18O_2 species. The second part is making a global fit of the rotational and vibrational transitions for the excited vibrational states. For the v_2 band, we will complete the recent I.R. analysis. About the triad (v_1, 2v_2, v_3): 32S18O_2 species was studied, but not the 32S16O18O one. and 145 GHz concerning the 32S18O_2 species. The second part is making a global fit of the rotational and vibrational transitions for the excited vibrational states. For the v_2 band, we will complete the recent I.R. analysis. About the triad (v_1, 2v_2, v_3): 32S18O_2 species was studied, but not the 32S16O18O one. The FT-IR spectra were recorded on the AILES Beamline at Synchrotron SOLEIL using the Synchrotron light source, coupled to the Bruker IFS125HR Fourier transform spectrometer. The THz spectra were obtained from 150 to 1500 GHz using the Lille's solid state spectrometer. The analysis is in progress, the latest results will be presented. Support from the French Laboratoire d'Excellence CaPPA (Chemical and Physical Properties of the Atmosphere) through contract ANR-10-LABX-0005 of the Programme d'Investissements d'Avenir is acknowledged Belov, S. P.; et al., 1998, J. Mol. Spectrosc. 191, 17 Lindermayer, J.; et al., 1985, J. Mol. Spectrosc. 110, 357 Gueye, F.; et al. Mol. Phys. in press Ulenikov, O. N.; et al., 2015, JQSRT 166, 13 Brubach, J.; et al., 2010, AIP Conf. Proc. 1214, 81 Zakharenko, O.; et al., 2015, J. Mol. Spectrosc. 317, 41

  18. (/sup 6/Li,d) reactions on /sup 24/Mg and /sup 26/Mg at 73 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Tanabe, T.; Haga, K.; Yasue, M.; Sato, K. (Tokyo Univ., Tanashi (Japan). Inst. for Nuclear Study); Ogino, K.; Kadota, Y.; Tochi, M.; Makino, K. (Kyoto Univ. (Japan). Faculty of Engineering); Kitahara, T. (Yamanashi Medical Coll. (Japan)); Shiba, T. (Kyoto Univ. (Japan). Lab. of Nuclear Reaction)

    1983-05-09

    The sup(24,26)Mg(/sup 6/Li, d)sup(28,30)Si reactions have been studied at 73 MeV bombarding energy. The angular distributions were analyzed with exact finite-range distorted wave Born approximation calculations assuming a direct ..cap alpha..-cluster transfer. Extracted spectroscopic strengths leading to low-lying levels of /sup 28/Si and relative spectroscopic strengths between transitions to /sup 28/Si and /sup 30/Si ground states are consistent with those previously obtained by several ..cap alpha..-transfer reactions. Many strongly populated levels have been observed at Esub(x)> or approx.10 MeV for /sup 28/Si. A marked similarity was found between the deuteron spectrum and the /sup 24/Mg(..cap alpha.., ..cap alpha..)/sup 24/Mg excitation function in this excitation energy region. A brief comparison of the present ..cap alpha..-transfer results with previous two-nucleon transfer data leading to sup(28,30)Si is also presented.

  19. Formation of 24Mg* in the spallation of 28Si nuclei by 1-GeV protons

    Science.gov (United States)

    Vasenko, A. A.; Galanina, N. D.; Gusev, K. E.; Demidov, V. S.; Demidova, E. V.; Kirpichnikov, I. V.; Sokolov, A. Yu.; Starostin, A. S.; Khaldeeva, N. A.

    2006-11-01

    The 28Si(p, p' gamma)24Mg reaction has been studied at the ITEP accelerator by the hadron-gamma coincidence method for a proton energy of 1 GeV. Two reaction products are detected: a 1368.6-keV gamma-ray photon accompanying the transition of the 24Mg* nucleus from the first excited state to the ground state and a proton p' whose momentum is measured in a magnetic spectrometer. The measured distribution in the energy lost by the proton in interaction is attributed to five processes: the direct knockout of a nuclear alpha cluster, the knockout of four nucleons with a total charge number of 2, the formation of the DeltaSi isobaric nucleus, the formation of the Delta isobar in the interaction of the incident proton with a nuclear nucleon, and the production of a pi meson, which is at rest in the nuclear reference frame. The last process likely corresponds to the reaction of the formation of a deeply bound pion state in the 28P nucleus. Such states were previously observed only on heavy nuclei. The cross sections for the listed processes have been estimated.

  20. Formation of 24Mg* in the Splitting of 28Si Nuclei by 1-GeV Protons

    CERN Document Server

    Vasenko, A A; Gusev, K E; Demidov, V S; Demidova, E V; Kirpichnikov, I V; Sokolov, A Yu; Starostin, A S; Khaldeeva, N A

    2006-01-01

    The 28Si(p, p' gamma)24Mg reaction has been studied at the ITEP accelerator by the hadron-gamma coincidence method for a proton energy of 1 GeV. Two reaction products are detected: a 1368.6-keV gamma-ray photon accompanying the transition of the 24Mg* nucleus from the first excited state to the ground state and a proton p' whose momentum is measured in a magnetic spectrometer. The measured distribution in the energy lost by the proton in interaction is attributed to five processes: the direct knockout of a nuclear alpha cluster, the knockout of four nucleons with a total charge number of 2, the formation of the DeltaSi isobaric nucleus, the formation of the Delta isobar in the interaction of the incident proton with a nuclear nucleon, and the production of a pi meson, which is at rest in the nuclear reference frame. The last process likely corresponds to the reaction of the formation of a deeply bound pion state in the 28P nucleus. Such states were previously observed only on heavy nuclei. The cross sections ...

  1. Analysis and theoretical modeling of 18O enriched carbon dioxide spectrum by CRDS near 1.35 μm: (II) 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2 and 17O13C18O

    Science.gov (United States)

    Karlovets, E. V.; Campargue, A.; Kassi, S.; Tashkun, S. A.; Perevalov, V. I.

    2017-04-01

    This contribution is the second part of the analysis of the room temperature absorption spectrum of 18O enriched carbon dioxide by very high sensitivity Cavity Ring Down spectroscopy between 6977 and 7918 cm-1 (1.43-1.26 μm). Overall, more than 8600 lines belonging to 166 bands of eleven carbon dioxide isotopologues were rovibrationnally assigned. In a first part (Kassi et al. J Quant Spectrosc Radiat Transfer 187 (2017) 414-425, http://dx.doi.org/10.1016/j.jqsrt.2016.09.002), the results relative to mono-substituted isotopologues, 16O12C18O, 16O12C17O, 12C16O2 and 13C16O2, were presented. This second contribution is devoted to the multiply-substituted isotopologues or clumped isotopologues of particular importance in geochemistry: 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2 and 17O13C18O. On the basis of the predictions of effective Hamiltonian models, a total of 3195 transitions belonging to 73 bands were rovibrationnally assigned for these seven species. Among the 73 observed bands, 55 are newly reported. All the identified bands correspond to ΔP=10 and 11 series of transitions, where P= 2V1+V2+3V3 is the polyad number (Vi are vibrational quantum numbers). The accurate spectroscopic parameters of 70 bands have been determined from the standard band-by-band analysis. Global fits of the measured line intensities of the ΔP=10 series of transitions of 17O12C18O and 16O13C18O and of the ΔP=11 series of transitions of 12C18O2, 17O12C18O, 16O13C18O and 13C18O2 were performed to determine the corresponding sets of the effective dipole moment parameters.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Three-Dimensional Angular Momentum Projected Relativistic Point-Coupling Approach for Low-Lying Excited States in 24Mg

    Institute of Scientific and Technical Information of China (English)

    Yao Jiang-Ming; Meng Jie; D. Pena Arteaga; P. Ring

    2008-01-01

    A full three-dimensional angular momentum projection on top of a triaxial relativistic mean-field calculation is implemented for the first time. The underlying Lagrangian is a point coupling model and pairing correlations are taken into account by a monopole force. This method is applied for the low-lying excited states in 24Mg. Good agreement with the experimental data is found for the ground state properties. A minimum in the potential energy surface for the 2+ state, with β≈ 0.55, γ≈ 10°, is used as the basis to investigate the rotational energyspectrum as well as the corresponding B(E2) transition probabilities as compared to the available data.

  7. 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)

  8. 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.

  9. The infrared spectrum of the 12C 18O dimer

    Science.gov (United States)

    McKellar, A. R. W.

    2004-08-01

    The infrared spectrum of ( 12C 18O) 2 has been studied for the first time using a tunable diode laser spectrometer in the 2095 cm -1 region to probe a pulsed supersonic jet expansion. Very dilute gas mixtures of CO in He were used, resulting in small consumption of 12C 18O sample gas, as well as cold and simple spectra. The results were analyzed using a term value scheme to obtain model-independent energies for 7 rotational levels belonging to 2 stacks in the lower state, vCO=0, and 22 levels belonging to 7 stacks in the upper state, vCO=1. The two ground state isomers of the CO dimer were found to be separated by only 0.639 cm -1 for ( 12C 18O) 2. These results provide a foundation for future studies of the millimeter wave spectrum.

  10. Preliminary results of the search for exotic nuclei in the $^{18}O+ ^{18}O$ reaction mass of $^{19}$N

    CERN Document Server

    Détraz, C; Langevin, M; Roussel, P; Bernas, M; Pougheon, F; Vernotte, J

    1976-01-01

    A system has been built to identify low-cross section products of nuclear reactions and to accurately measure their energy. It includes a magnetic spectrometer and a detecting system in its focal plane consisting of two resistive-wire proportional counters and a set of four position-sensitive 5 cm-wide detectors. Six parameters are simultaneously determined: three positions, two Delta E-values, and the residual energy. This over-determination of the nature and energy of the detected nucleus is used to discriminate against background effects. In an experiment with a 91 MeV /sup 18/O beam from the Orsay MP-Tandem, /sup 19/N nuclei from the /sup 18/O(/sup 18/O,/sup 19/N) /sup 17/F reaction were observed and the mass excess of /sup 19/N was measured as 15.81+or-0.10 MeV.

  11. 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...

  12. Elastic and inelastic scattering of {sup 6}Li + {sup 18}O versus {sup 7}Li + {sup 18}O and {sup 6}Li + {sup 16}O

    Energy Technology Data Exchange (ETDEWEB)

    Rudchik, Adam T., E-mail: rudchik@kinr.kiev.ua [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Kliczewski, Stanislaw [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland); Chercas, Kostyantyn A. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Kemper, Kirby W. [Physics Department, Florida State University, Tallahassee, FL 32306-4350 (United States); Koshchy, Evgeniy I. [Kharkiv National University, pl. Svobody 4, 61077 Kharkiv (Ukraine); Rusek, Krzysztof [National Centre for Nuclear Research, ul. Hoża 69, PL-00-681 Warsaw (Poland); Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Rudchik, Andryi A.; Mezhevych, Sergyi Yu.; Pirnak, Valeryi M. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Plujko, Volodymyr A. [Taras Shevchenko Kyiv National University, vul. Volodymyrs' ka 64, 01033 Kyiv (Ukraine); Ponkratenko, Oleg A. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Choiński, Jaroslaw [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Czech, Bronislaw; Siudak, Regina; Szczurek, Antoni [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland); Stolarz, Anna [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Zelinskyi, Ruslan M. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine)

    2014-02-15

    Inverse kinematics scattering of {sup 18}O on {sup 6}Li at E{sub lab}({sup 18}O) = 114 MeV was measured to obtain elastic and inelastic scattering cross sections. In this way cross sections for excited states in {sup 6}Li and {sup 18}O were determined. The data were analyzed within the optical model and coupled reaction channel method. The {sup 6}Li + {sup 18}O optical potential as well as the {sup 6}Li and {sup 18}O deformation parameters were deduced. Contributions of different nuclear processes to the {sup 6}Li + {sup 18}O elastic and inelastic scattering were explored. The isotopic differences between the {sup 6,7}Li + {sup 18}O and {sup 6}Li + {sup 16,18}O potential parameters were determined.

  13. Forward modeling of δ18O in Andean ice cores

    Science.gov (United States)

    Hurley, J. V.; Vuille, M.; Hardy, D. R.

    2016-08-01

    Tropical ice core archives are among the best dated and highest resolution from the tropics, but a thorough understanding of processes that shape their isotope signature as well as the simulation of observed variability remain incomplete. To address this, we develop a tropical Andean ice core isotope forward model from in situ hydrologic observations and satellite water vapor isotope measurements. A control simulation of snow δ18O captures the mean and seasonal trend but underestimates the observed intraseasonal variability. The simulation of observed variability is improved by including amount effects associated with South American cold air incursions, linking synoptic-scale disturbances and monsoon dynamics to tropical ice core δ18O. The forward model was calibrated with and run under present-day conditions but can also be driven with past climate forcings to reconstruct paleomonsoon variability. The model is transferable and may be used to render a (paleo)climatic context at other ice core locations.

  14. Laser-based measurements of 18O/16O stable isotope ratios (δ18O in wine samples

    Directory of Open Access Journals (Sweden)

    Gupta M

    2013-09-01

    Full Text Available Manish Gupta,1 J Brian Leen,1 Elena Simone Franklin Berman,1 Aldo Ciambotti2 1Los Gatos Research, Mountain View, CA, USA; 2Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per l'Enologia, Asti, Italy Abstract: Wine counterfeiting is an international, multi-billion dollar issue, with some estimates suggesting that up to 5% of wines sold at auctions or secondary markets are fraudulent. Isotope ratio mass spectrometer (IRMS measurements of the 18O/16O stable isotope ratio (δ18O of water-in-wine have been used for wine authentication; however, these analyses are time-consuming and costly. In this preliminary study, off-axis integrated cavity output spectroscopy (OA-ICOS is used to quantify δ18O in wines. This laser-based method has been extensively used to study water isotopes for hydrological and medical applications. Recently, the development of a spectral contaminant identifier (SCI has extended the application of these OA-ICOS analyzers to contaminated water samples (eg, plant, soil, and leaf waters. Here, we utilize OA-ICOS with the SCI to characterize wine samples (9%–15% ethanol, and show that the laser-based instrument provides a δ18O measurement precision of ±0.07‰ (1σ and agrees with IRMS to within ±0.63‰ (1σ. Moreover, by training the SCI on isotopically-characterized wines, the agreement with IRMS improves to within ±0.30‰ (1σ. The utility of the instrument is demonstrated by measuring watered and mixed wines. The method presented here can be readily extended to address other food authentication applications. Keywords: wine isotopes, wine fraud, counterfeit wines, OA-ICOS

  15. Calculation of vibrational branching ratios and hyperfine structure of 24Mg19F and its suitability for laser cooling and magneto-optical trapping

    Science.gov (United States)

    Xu, Liang; Yin, Yanning; Wei, Bin; Xia, Yong; Yin, Jianping

    2016-01-01

    More recently, laser cooling of the diatomic radical magnesium monofluoride (24Mg19F ) is being experimentally preformed [Appl. Phys. Express 8, 092701 (2015), 10.7567/APEX.8.092701 and Opt. Express 22, 28645 (2014), 10.1364/OE.22.028645] and was also studied theoretically [Phys. Rev. A 91, 042511 (2015), 10.1103/PhysRevA.91.042511]. However, some important problems still remain unsolved, so, in our paper, we perform further theoretical study for the feasibility of laser cooling and trapping the 24Mg19F molecule. At first, the highly diagonal Franck-Condon factors of the main transitions are verified by the closed-form approximation, Morse approximation, and Rydberg-Klein-Rees inversion methods, respectively. Afterwards, we investigate the lower X 2Σ1/2 + hyperfine manifolds using a quantum effective Hamiltonian approach and obtain the zero-field hyperfine spectrum with an accuracy of less than 30 kHz ˜5 μ K compared with the experimental results, and then find out that one cooling beam and one or two repumping beams with their first-order sidebands are enough to implement an efficient laser slowing and cooling of 24Mg19F . Meanwhile, we also calculate the accurate hyperfine structure magnetic g factors of the rotational state (X 2Σ1/2 +,N =1 ) and briefly discuss the influence of the external fields on the hyperfine structure of 24Mg19F as well as its possibility of preparing three-dimensional magneto-optical trapping. Finally we give an explanation for the difference between the Stark and Zeeman effects from the perspective of parity and time reversal symmetry. Our study shows that, besides appropriate excitation wavelengths, the short lifetime for the first excited state A 2Π1 /2 , and lighter mass, the 24Mg19F radical could be a good candidate molecule amenable to laser cooling and magneto-optical trapping.

  16. 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).

  17. 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.

  18. 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,...

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. The in vitro biological activities of synthetic 18-O-methyl mycalamide B, 10-epi-18-O-methyl mycalamide B and pederin.

    Science.gov (United States)

    Richter, A; Kocienski, P; Raubo, P; Davies, D E

    1997-04-01

    Mycalamides A and B, which were originally isolated from a marine sponge, show close structural similarity to the insect toxin pederin, and exhibit potent cytotoxicity and antitumour activity. Detailed investigation of the clinical potential of these compounds has been hampered because they are available in only minute quantities from natural sources. We now describe the biological activities of 18-O-methyl mycalamide B, 10-epi-18-O-methyl mycalamide and pederin, all prepared by total synthesis. The activities of 18-O-methyl mycalamide B and pederin were virtually indistinguishable when evaluated in DNA or protein synthesis assays, and in cytotoxicity assays using human carcinoma cell lines (IC50s 0.2-0.6 nM). In all assays, 10-epi-18-O-methyl mycalamide B was 10(3) times less toxic than its diastereoisomer, demonstrating that the cytotoxicity of 18-O-methyl mycalamide B is inseparable from its ability to inhibit protein synthesis. Short-term exposure of squamous carcinoma cells to 18-O-methyl mycalamide B or pederin caused an irreversible inhibition of cellular proliferation and induced cellular necrosis. In contrast, the antiproliferative effects of the compounds on human fibroblasts were reversible and there was no evidence of necrosis. Demonstration that 18-O-methyl mycalamide B and the synthetically less complex molecule, pederin, show some tumour cell toxicity indicates that this novel class of compounds should be subjected to preclinical evaluation.

  4. Isovector stretched-state excitations in the sup 20 Ne, sup 24 Mg, sup 28 Si, and sup 32 S( p , n ) reactions at 136 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Tamimi, N.; Anderson, B.D.; Baldwin, A.R.; Chittrakarn, T.; Elaasar, M.; Madey, R.; Manley, D.M.; Mostajabodda' vati, M.; Watson, J.W.; Zhang, W. (Department of Physics, Kent State University, Kent, Ohio 44242 (United States)); Carr, J.A. (Supercomputer Computations Research Institute, The Florida State University, Tallahassee, Florida 32306 (United States)); Foster, C.C. (Indiana University Cyclotron Facility, Bloomington, Indiana 47408 (United States))

    1992-03-01

    Isovector stretched-state excitations were studied in the ({ital p},{ital n}) reaction at 136 MeV on the self-conjugate {ital s}-{ital d} shell nuclei {sup 20}Ne, {sup 24}Mg, {sup 28}Si, and {sup 32}S. The measurements were performed in three separate experiments using the beam-swinger neutron time-of-flight facility at the Indiana University Cyclotron Facility. Neutrons were detected in large-volume plastic scintillation detectors located in three detector stations at 0{degree}, 24{degree}, and 45{degree} with respect to the undeflected beam line; the flight paths varied from 75 to 134 m. Overall time resolutions of about 825 ps provided energy resolutions of about 320 keV in the first two stations and about 425 keV in the third station. Both ({ital d}{sub 5/2},{ital d}{sub 5/2}{sup {minus}1})5{sup +} 0{h bar}{omega} and ({ital f}{sub 7/2},{ital d}{sub 5/2}{sup {minus}1})6{sup {minus}} 1{h bar}{omega} stretched-state excitations are observed in the ({ital p},{ital n}) reaction on {sup 20}Ne, {sup 24}Mg, and {sup 28}Si.

  5. 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...

  6. 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.

  7. Actinide production from the interactions of sup 40 Ca and sup 44 Ca with sup 248 Cm and a comparison with the sup 48 Ca+ sup 248 Cm system

    Energy Technology Data Exchange (ETDEWEB)

    Tuerler, A.; von Gunten, H.R. (Laboratorium fuer Radiochemie, Universitaet Bern, 3000 Bern 9 (Switzerland)); Leyba, J.D.; Hoffman, D.C.; Lee, D.M.; Gregorich, K.E.; Bennett, D.A.; Chasteler, R.M.; Gannett, C.M.; Hall, H.L.; Henderson, R.A.; Nurmia, M.J. (Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States))

    1992-10-01

    Excitation functions have been measured for production of isotopes of Th through Fm in bombardments of {sup 248}Cm with 231- to 323-MeV {sup 44}Ca ions and for the production of isotopes of Th through Cm in bombardments of {sup 248}Cm with 230- to 291-MeV {sup 40}Ca ions, respectively, using radiochemical methods. Upper production cross section limits were established for nuclides that were not positively detected. The experimental data were compared with the results of previous reaction studies in the systems {sup 40}Ca+{sup 248}Cm and {sup 48}Ca+{sup 248}Cm. The half-widths of the Gaussian isotopic distributions were about 2.5 mass numbers for above-target elements and 5 to 5.5 mass numbers for below-target elements in all three systems. The majority of the cross section for the production of above-target nuclides was assigned to predominantly quasielastic reactions, whereas below-target nuclides were formed in deeply inelastic and asymmetric quasifission reactions. The maxima of the isotopic distributions were shown by others to closely follow the minimum of the potential energy surface in experiments with {sup 48}Ca, whereas in reactions with {sup 40}Ca and {sup 44}Ca we found that a transfer of 4 to 5 protons in either direction was required to reach the minimum in potential energy.

  8. $^{8}$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.

  9. 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.

  10. 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.

  11. Three-dimensional angular momentum projected relativistic point-coupling approach for the low-lying excited states in $^{24}$Mg

    CERN Document Server

    Yao, J M; Arteaga, D Pena; Ring, P; 10.1088/0256-307X/25/10/024

    2008-01-01

    A full three-dimensional angular momentum projection on top of a triaxial relativistic mean-Geld calculation is implemented for the first time. The underlying Lagrangian is a point coupling model and pairing correlations are taken into account by a monopole force. This method is applied for the low-lying excited states in 24Mg. Good agreement with the experimental data is found for the ground state properties. A minimum in the potential energy surface for the 2+ state, with beta = 0.55, gamma = 10 deg, is used as the basis to investigate the rotational energy spectrum as well as the corresponding B(E2) transition probabilities as compared to the available data.

  12. Gamow-Teller strength in the ( p , n ) reaction at 136 MeV on sup 20 Ne, sup 24 Mg, and sup 28 Si

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, B.D.; Tamimi, N.; Baldwin, A.R.; Elaasar, M.; Madey, R.; Manley, D.M.; Mostajabodda' vati, M.; Watson, J.W.; Zhang, W.M. (Department of Physics, Kent State University, Kent, Ohio 44242 (USA)); Foster, C.C. (Indiana University Cyclotron Facility, Bloomington, Indiana 47408 (USA))

    1991-01-01

    Gamow-Teller (GT) strength distributions were studied in the ({ital p},{ital n}) reaction at 136 MeV on the self-conjugate {ital s}-{ital d} shell nuclei {sup 20}Ne, {sup 24}Mg, and {sup 28}Si. The measurements were performed in two separate experiments with the beam-swinger neutron time-of-flight facility at the Indiana University Cyclotron Facility. The flight paths were 91 and 131 m, respectively, for the two experiments. The neutrons were detected in large-volume plastic-scintillation detectors. The overall time resolutions were about 825 ps; this provided energy resolutions from 300 to 400 keV. GT strength was identified as {Delta}{ital l}=0 contributions in transitions to discrete final states and also in the background and continuum. The 0{degree}, {Delta}l=0 cross sections were converted to {ital B}(GT) units using a universal'' conversion formula calibrated to ({ital p},{ital n}) reactions on other even-even {ital s}-{ital d} shell nuclei. The resulting {ital B}(GT) distributions were compared with full {ital s}-{ital d} shell-model predictions. The distribution for {sup 24}Mg is described well, but the distributions for {sup 20}Ne and {sup 28}Si are described poorly. The total {ital B}(GT) strength observed in discrete states (up to 12 MeV of excitation) for each reaction is 65{plus minus}10 % of that predicted. If one considers {ital B}(GT) strength observed in the continuum above a calculated quasi-free-scattering background, the strength increases to 70--100 % of that predicted. If one considers {ital B}(GT) strength in an analysis of the full continuum (up to {similar to}20 MeV), the entire amount predicted may be observed. These results are consistent with that observed in other light nuclei.

  13. 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

  14. True absorption and scattering of pions on 16O and 18O

    Science.gov (United States)

    Navon, I.; Piasetzky, E.; Ashery, D.; Altman, A.; Azuelos, G.; Schlepütz, F. W.; Walter, H. K.

    1980-10-01

    The inclusive pion inelastic scattering and true absorption cross sections on 16O and 18O were measured at 165 MeV for π± and at 315 MeV for π+. The results show large effects of the two neutrons in 18O on the absorption and inelastic scattering cross sections at the resonance energy. In particular, the inelastic scattering of π+ from 18O is considerably smaller than from 16O and this effect is attributed to the coupling between the reaction channels.

  15. 18O labeling of chlorophyll d in Acaryochloris marina reveals that chlorophyll a and molecular oxygen are precursors.

    Science.gov (United States)

    Schliep, Martin; Crossett, Ben; Willows, Robert D; Chen, Min

    2010-09-10

    The cyanobacterium Acaryochloris marina was cultured in the presence of either H(2)(18)O or (18)O(2), and the newly synthesized chlorophylls (Chl a and Chl d) were isolated using high performance liquid chromatography and analyzed by mass spectroscopy. In the presence of H(2)(18)O, newly synthesized Chl a and d, both incorporated up to four isotopic (18)O atoms. Time course H(2)(18)O labeling experiments showed incorporation of isotopic (18)O atoms originating from H(2)(18)O into Chl a, with over 90% of Chl a (18)O-labeled at 48 h. The incorporation of isotopic (18)O atoms into Chl d upon incubation in H(2)(18)O was slower compared with Chl a with approximately 50% (18)O-labeled Chl d at 115 h. The rapid turnover of newly synthesized Chl a suggested that Chl a is the direct biosynthetic precursor of Chl d. In the presence of (18)O(2) gas, one isotopic (18)O atom was incorporated into Chl a with approximately the same kinetic incorporation rate observed in the H(2)(18)O labeling experiment, reaching over 90% labeling intensity at 48 h. The incorporation of two isotopic (18)O atoms derived from molecular oxygen ((18)O(2)) was observed in the extracted Chl d, and the percentage of double isotopic (18)O-labeled Chl d increased in parallel with the decrease of non-isotopic-labeled Chl d. This clearly indicated that the oxygen atom in the C3(1)-formyl group of Chl d is derived from dioxygen via an oxygenase-type reaction mechanism.

  16. High-Resolution Spectra of the 10B18O and 11B18O: Rotational Analysis of the B-X Bands

    Institute of Scientific and Technical Information of China (English)

    V.Bojovic; A.Anti6-Jovanovi(c); M.Kuzmanovi(c)

    2005-01-01

    @@ Emission spectra of 10B18O and 11 B18O isotopomers in the 230-330 nm region have been investigated by means of conventional high-resolution spectroscopy.The molecules were produced in a low-pressure arc by discharging 8 Torr of mixture containing argon and oxygen 18 in the ratio of 4:1 and the spectra have been recorded using Ebert-type spectrograph.The boron needed to produce BO has been present in the system as amorphous powder with natural abundance of 10B and 11 B.Rotational analysis of the 0, 0 and 0, 1 bands has been performed and spectroscopic constants have been extracted.The results have allowed first determination of the equilibrium rotational constants Be and De for both isotope species 10B18O and 11B18O in their lower electronic state.Assuming a linear dependence of Be on (v + 1/2), the value of equilibrium distance re in the lower state has been derived.

  17. 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...

  18. 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...

  19. 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...

  20. 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 sparse...

  1. Secas Island Stable Isotope Data (delta 18O) for 1707 to 1984

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Secas Island Coral d18O, used to reconstruct seasonal and interannual variability in the Intertropical Convergence Zone. Site Location: Secas Island, Gulf of...

  2. 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 (cf....

  3. 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.

  4. 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.

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

    OpenAIRE

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

    2016-01-01

    Abstract Spatial variation in marine oxygen isotope ratios (δ 18O) resulting from differential evaporation rates and precipitation inputs is potentially useful for characterizing marine mammal distributions and tracking movements across δ 18O 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 comp...

  6. 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.

  7. Regional and global benthic δ18O stacks for the last glacial cycle

    Science.gov (United States)

    Lisiecki, Lorraine E.; Stern, Joseph V.

    2016-10-01

    Although detailed age models exist for some marine sediment records of the last glacial cycle (0-150 ka), age models for many cores rely on the stratigraphic correlation of benthic δ18O, which measures ice volume and deep ocean temperature change. The large amount of data available for the last glacial cycle offers the opportunity to improve upon previous benthic δ18O compilations, such as the "LR04" global stack. Not only are the age constraints for the LR04 stack now outdated but a single global alignment target neglects regional differences of several thousand years in the timing of benthic δ18O change during glacial terminations. Here we present regional stacks that characterize mean benthic δ18O change for 8 ocean regions and a volume-weighted global stack of data from 263 cores. Age models for these stacks are based on radiocarbon data from 0 to 40 ka, correlation to a layer-counted Greenland ice core from 40 to 56 ka, and correlation to radiometrically dated speleothems from 56 to 150 ka. The regional δ18O stacks offer better stratigraphic alignment targets than the LR04 global stack and, furthermore, suggest that the LR04 stack is biased 1-2 kyr too young throughout the Pleistocene. Finally, we compare global and regional benthic δ18O responses with sea level estimates for the last glacial cycle.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. C18O Observations of the Dark Molecular Cloud L134 and Gas Depletion onto Dust

    Institute of Scientific and Technical Information of China (English)

    Xin-Jie Mao; Xiao-Xia Sun

    2005-01-01

    We map the dark molecular cloud core of L134 in the C18O (J =1 -0) emission line using the PMO 13.7m telescope, and present a contour map of integrated intensity of C18O (J = 1 - 0) emission. The C18O cloud is inside the distribution of extinction AB, the visual extinction of blue light, as well as inside the 13CO cloud in the L134 region. The depletion factors in this C18O cloud are generally greater than unity, which means there is gas depletion onto dust. Since only a minimum AB = 9.7 mag is available, and our observations measure both undepleted and depleted regions along the line of sight, the depletion factors could very likely be larger in the central core than the calculated value. So we conclude that depletion does occur in the bulk of the C18O cloud through a comparison between the C18O and blue extinction maps in the L134 region. There is no direct evidence as yet for star formation in L134, and so cores on the verge of collapse will not be visible in CO and other gas molecules.

  13. 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

  14. δ18O analysis of individual carbohydrates - a new method for GC-pyrolysis-IRMS

    Science.gov (United States)

    Lehmann, Marco M.; Fischer, Maria; Zech, Michael; Siegwolf, Rolf T. W.; Saurer, Matthias

    2015-04-01

    Measuring the oxygen isotopic composition (δ18O) of various plant tissues is a widely used tool to investigate biochemical and physiological processes. While we have a good understanding about the hydrological cycle in plants with an evaporative enrichment in 18O in leaf water, we still lack knowledge about the biochemical link between the oxygen atoms in leaf water, leaf assimilates, and stem cellulose and associated isotope fractionations. Especially, the influence of different environmental factors on δ18O of individual carbohydrates (i.e. sugars) and thus on δ18O of cellulose is not fully resolved. A better understanding of these processes may improve climatic reconstructions of tree-ring studies about past environmental conditions. However, further progress in this topic is limited since a precise and reliable method to determine δ18O of individual sugars has not been available yet. With our new approach we attempt to overcome this issue by establishing a new methylation derivatization method suitable for GC-pyrolysis -IRMS. A methyl group (CH3) was thereby added to all hydroxyl groups of a sugar (e.g., glucose, fructose, and sucrose) during a catalyzed one-pot reaction overnight in acetonitrile with methyl iodide (CH3-I) and silver oxide, making them amenable for GC analysis. First results show a very good precision for δ18O of sucrose, but also δ18O of other high-abundant sugars such as glucose and fructose could be measured for the first time. We successfully analyzed a standard mix of all three sugars and determined various other carbohydrates not only related to plant sciences (e.g. mannitol, lactose), showing promising δ18O results. First tests with real plant samples were performed to make this method available for determining δ18O of individual carbohydrates of diverse plant tissues. In future, this new methylation derivatization method should allow us analyzing plant samples of different field sites and of lab experiments to investigate the

  15. 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.

  16. Oxygen isotope evolution of the Lake Owyhee volcanic field, Oregon, and implications for the low-δ18O magmatism of the Snake River Plain-Yellowstone hotspot and other low-δ18O large igneous provinces

    Science.gov (United States)

    Blum, Tyler B.; Kitajima, Kouki; Nakashima, Daisuke; Strickland, Ariel; Spicuzza, Michael J.; Valley, John W.

    2016-11-01

    The Snake River Plain-Yellowstone (SRP-Y) hotspot track represents the largest known low-δ18O igneous province; however, debate persists regarding the timing and distribution of meteoric hydrothermal alteration and subsequent melting/assimilation relative to hotspot magmatism. To further constrain alteration relations for SRP-Y low-δ18O magmatism, we present in situ δ18O and U-Pb analyses of zircon, and laser fluorination δ18O analyses of phenocrysts, from the Lake Owyhee volcanic field (LOVF) of east-central Oregon. U-Pb data place LOVF magmatism between 16.3 and 15.4 Ma, and contain no evidence for xenocrystic zircon. LOVF δ18O(Zrc) values demonstrate (1) both low-δ18O and high-δ18O caldera-forming and pre-/post-caldera magmas, (2) relative increases in δ18O between low-δ18O caldera-forming and post-caldera units, and (3) low-δ18O magmatism associated with extension of the Oregon-Idaho Graben. The new data, along with new compilations of (1) in situ zircon δ18O data for the SRP-Y, and (2) regional δ18O(WR) and δ18O(magma) patterns, further constrain the thermal and structural associations for hydrothermal alteration in the SRP-Y. Models for low-δ18O magmatism must be compatible with (1) δ18O(magma) trends within individual SRP-Y eruptive centers, (2) along axis trends in δ18O(magma), and (3) the high concentration of low-δ18O magmas relative to the surrounding regions. When considered with the structural and thermal evolution of the SRP-Y, these constraints support low-δ18O magma genesis originating from syn-hotspot meteoric hydrothermal alteration, driven by hotspot-derived thermal fluxes superimposed on extensional tectonics. This model is not restricted to continental hotspot settings and may apply to several other low-δ18O igneous provinces with similar thermal and structural associations.

  17. Clay aquitards as archives of holocene paleoclimate: delta18O and thermal profiling.

    Science.gov (United States)

    Hendry, M Jim; Woodbury, A D

    2007-01-01

    Paleoclimatic conditions in the Holocene were reconstructed from a detailed vertical profile of pore water delta(18)O and a series of downhole thermal profiles at a thick, hydrogeologically simple, aquitard research site in the Northern Great Plains of Saskatchewan. Reconstructions were obtained using the theory of one-dimensional diffusive transport and an empirical Bayesian inversion technique. Inversion of the delta(18)O profile shows that input signal consists of a sudden increase of +6 per thousand (corresponding to a temperature increase of about 18 degrees C) at about 12,000 years before present (BP), after which no measurable change in delta(18)O is apparent to present day. This research shows, at this location, that there is no evidence of large amplitude temperature shifts in the Holocene and supports the commonly used assumption in ground water studies of constant atmospheric delta(18)O values throughout the Holocene. Inversion of the temperature profiles suggests the ground surface temperature increased primarily in the last half of the 20th century, with a peak temperature (about 3 degrees C) circa 1990. For both profiles, the ability to resolve historical variability decays rapidly with time. For the temperature profiles, the decay in resolution precluded the development of reliable estimates of climatic conditions prior to about 1950 and, in the case of the delta(18)O profile, it prevented the precise definition of climate changes (e.g., Hypsithermal and Little Ice Age) in the Holocene.

  18. Using 18O as a Tracer of Oxygen in the Photochemical Alteration of Dissolved Organic Matter

    Science.gov (United States)

    Davis, J. A.; Stubbins, A.; Helms, J.; Dias, R. F.; Mopper, K.

    2006-12-01

    The biogeochemical cycling of dissolved organic matter (DOM) in natural waters is affected by numerous processes, including photochemical alteration. Photochemical processes result in the net oxidation and mineralization of DOM concomitant with dissolved oxygen consumption and production of dissolved inorganic carbon (DIC; principally CO2). The photochemical oxygen budget is not well constrained while DIC production accounts for nearly all the dissolved oxygen consumed, conflicting data suggests that more than half of the oxygen consumed is required to account for observed DOM oxidation and hydrogen peroxide production. An alternate source of oxygen is required to balance this budget; water itself may provide the answer. In order to determine the source of oxygen, a number of time series irradiations were performed using Great Dismal Swamp water (southeast Virginia) with 18O enrichments as either dissolved oxygen or water. Early results, upon irradiation in a UV solar simulator, show significant incorporation of 18O-enriched oxygen into high molecular weight (HMW) DOM from both sources. While the majority of the incorporated oxygen originated from the dissolved oxygen, at least 5 percent originated from water. Data will be presented showing the rate and degree of incorporation of 18O-enriched oxygen from both sources as well as the production of 18O-enriched carbon dioxide. The movement of 18O label will be discussed in relation to shifts in spectral qualities, including photobleaching and spectral slope, of the irradiated samples and selective incorporation as detailed by FT-ICRMS.

  19. 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.

  20. Isotope parameters (δD, δ18O) and sources of freshwater input to Kara Sea

    Science.gov (United States)

    Dubinina, E. O.; Kossova, S. A.; Miroshnikov, A. Yu.; Fyaizullina, R. V.

    2017-01-01

    The isotope characteristics (δD, δ18O) of Kara Sea water were studied for quantitative estimation of freshwater runoff at stations located along transect from Yamal Peninsula to Blagopoluchiya Bay (Novaya Zemlya). Freshwater samples were studied for glaciers (Rose, Serp i Molot) and for Yenisei and Ob estuaries. As a whole, δD and δ18O are higher in glaciers than in river waters. isotope composition of estuarial water from Ob River is δD =-131.4 and δ18O =-17.6‰. Estuarial waters of Yenisei River are characterized by compositions close to those of Ob River (-134.4 and-17.7‰), as well as by isotopically "heavier" compositions (-120.7 and-15.8‰). Waters from studied section of Kara Sea can be product of mixing of freshwater (δD =-119.4, δ18O =-15.5) and seawater (S = 34.9, δD = +1.56, δ18O = +0.25) with a composition close to that of Barents Sea water. isotope parameters of water vary significantly with salinity in surface layer, and Kara Sea waters are desalinated along entire studied transect due to river runoff. concentration of freshwater is 5-10% in main part of water column, and 100 m. maximum contribution of freshwater (>65%) was recorded in surface layer of central part of sea.

  1. Pion-induced nucleon knockout reactions on 16O and 18O

    Science.gov (United States)

    Piasetzky, E.; Altman, A.; Lichtenstadt, J.; Yavin, A. I.; Ashery, D.; Bertl, W.; Felawka, L.; Walter, H. K.; Schlepütz, F. W.; Powers, K. J.; Winter, R. G.; Pluym, J. V. D.

    1982-12-01

    The (π+, π+p), (π-, π-p), and (π-, π-n) reactions on 16O and 18O were studied at 165 MeV by coincidence measurements of the outgoing particles. The cross sections for the (π-, π-n) reaction is larger on 18O than on 16O, whereas those for the (π+, π+p) and the (π-, π-p) reactions are smaller, most likely because of the coupling between the absorption and the scattering channels. NUCLEAR REACTIONS (π+/-, π+/-p) (π-, π-n) coin. Measurements on 16O18O E=165 MeV; deduced coupling between the absorption and the scattering channels.

  2. 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

  3. 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.

  4. 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.

  5. Isotopic effects in the ( π±, 2N) reactions on 16O and 18O

    Science.gov (United States)

    Altman, A.; Ashery, D.; Piasetzky, E.; Lichtenstadt, J.; Yavin, A. I.; Bertl, W.; Felawka, L.; Walter, H. K.; Powers, R. J.; Winter, R. G.; v. d. Pluym, J.

    1984-09-01

    The ( π+, 2p), ( π+, pn) and ( π-, pn) reactions on 16O and 18O were studied at 165 MeV. The cross section for the ( π+, 2p) reaction on 18O is larger than that for 16O be only 5% ± 3%, while the total π+ absorption cross section is larger by 17% ± 5%. This supports the assumption that two-nucleon absorption occurs mainly on nucleons in the same shell. It is further concluded that Δ++n → pp is not only absorption mechanism that couples strongly to the nucleon knock out reactions.

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

    OpenAIRE

    K. Schollaen; C. Karamperidou; P. Krusic; Cook, E; Helle, G.

    2015-01-01

    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 ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Gates, Jacklyn; Dragojevic, Irena; Dvorak, Jan; Ellison, Paul; Gregorich, Kenneth; Stavsetra, Liv; Nitsche, Heino

    2009-02-02

    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.

  8. Co-hydrothermal synthesis of LiMn23/24Mg1/24PO4·LiAlO2/C nano-hybrid cathode material with enhanced electrochemical performance for lithium-ion batteries

    Science.gov (United States)

    Zhang, Jun; Luo, Shaohua; Chang, Longjiao; Hao, Aimin; Wang, Zhiyuan; Liu, Yanguo; Xu, Qian; Wang, Qing; Zhang, Yahui

    2017-02-01

    LiMn23/24Mg1/24PO4·LiAlO2/C is synthesized by a co-hydrothermal method in water/PEG system using Li2CO3, AAO and Mn1-xMgxPO4 as raw material. The electronic structure and micromorphology of multi-component compound LiMn1-xMgxPO4/C (x = 0, 1/24, 1/12, 1/6) and nano-hybrid LiMn23/24Mg1/24PO4·LiAlO2/C cathode materials are studied by first-principles calculation and experimental research including XRD, SEM, TEM. The calculated band gap of LiMn23/24Mg1/24PO4/C is 2.296 eV, which is lower than other percentages Mg2+ doping samples. Electrochemical tests exhibit LiMn23/24Mg1/24PO4/C has better cycling performance and rate capability than other contents Mg2+ doping samples with the discharge capacity of 143.5 mAh/g, 141.5 mAh/g, 139.2 mAh/g and 136.3 mAh/g at 0.05C, 0.1C, 0.5C and 1C in order. After compositing and preparation of LiMn23/24Mg1/24PO4·LiAlO2/C composite material by co-hydrothermal route, the initial discharge capacity reaches up to 151.8 mAh/g, which suggests that co-modified with Mg2+ doping and LiAlO2 compositing material can improve the electronic conductivity of LiMnPO4/C by facilitating the lithium ion diffusion rate in the interior of the materials.

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

    Directory of Open Access Journals (Sweden)

    D. Dahl-Jensen

    2012-12-01

    Full Text Available 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 Greenland. Furthermore, the sensitivity of accumulation rate to changes in temperature is found to be smaller in Northern Greenland than in the central and southern parts. Four records in the data set contain sufficient recent data that the period of observed temperature rise from the 1990s and onwards can be investigated. All four records are from locations close to the ice divide in Northern Greenland and while three of them show increased temperatures, no conclusive statement can be made about the accumulation rate from these data.

  10. 18O and 226Ra in the Minjiang River estuary, China and their hydrological implications

    Science.gov (United States)

    Liu, Huatai; Guo, Zhanrong; Gao, Aiguo; Yuan, Xiaojie; Zhang, Bin

    2016-05-01

    In this work, the 2H, 18O and 226Ra values in groundwater and surface water in the Minjiang River estuary were investigated in the dry and wet seasons. The δ18O values in the dry season were always higher than those in the wet season in both groundwater and surface water because of the presence of evaporation in the water cycle process. During the dry season, the δ18O values in groundwater on the southern bank of the Minjiang River are much higher than those on the northern bank because evaporation is more intense in the farmland of the southern bank than in the urbanized northern bank. The δ18O values in the estuarine water exhibit a good positive correlation with salinity, with a coefficient of 0.96 (p = 0.05) in both seasons. The 226Ra activities in the estuarine water increase with increasing salinity because of desorption from riverine suspended particles. The 226Ra activity reaches a peak value at a salinity of 20.5. Based on a three-endmember model, the average proportions of the estuarine water are calculated to be 0.02 for groundwater, 0.39 for river water and 0.59 for seawater. From this mixing ratio, the groundwater discharge into the estuary is estimated to be 9.31 × 106 m3 d-1 in the wet season.

  11. The 18O signature of biogenic nitrous oxide is determined by O exchange with water

    NARCIS (Netherlands)

    Kool, D.M.; Wrage, N.; Oenema, O.; Harris, D.; Groenigen, van J.W.

    2009-01-01

    To effectively mitigate emissions of the greenhouse gas nitrous oxide (N2O) it is essential to understand the biochemical pathways by which it is produced. The 18O signature of N2O is increasingly used to characterize these processes. However, assumptions on the origin of the O atom and resultant is

  12. 13CO/C18O Gradients across the Disks of Nearby Spiral Galaxies

    Science.gov (United States)

    Jiménez-Donaire, María J.; Cormier, Diane; Bigiel, Frank; Leroy, Adam K.; Gallagher, Molly; Krumholz, Mark R.; Usero, Antonio; Hughes, Annie; Kramer, Carsten; Meier, David; Murphy, Eric; Pety, Jérôme; Schinnerer, Eva; Schruba, Andreas; Schuster, Karl; Sliwa, Kazimierz; Tomicic, Neven

    2017-02-01

    We use the IRAM Large Program EMPIRE and new high-resolution ALMA data to measure 13CO(1-0)/C18O(1-0) intensity ratios across nine nearby spiral galaxies. These isotopologues of 12CO are typically optically thin across most of the area in galaxy disks, and this ratio allows us to gauge their relative abundance due to chemistry or stellar nucleosynthesis effects. Resolved 13CO/C18O gradients across normal galaxies have been rare due to the faintness of these lines. We find a mean 13CO/C18O ratio of 6.0 ± 0.9 for the central regions of our galaxies. This agrees well with results in the Milky Way, but differs from results for starburst galaxies (3.4 ± 0.9) and ultraluminous infrared galaxies (1.1 ± 0.4). In our sample, the 13CO/C18O ratio consistently increases with increasing galactocentric radius and decreases with increasing star formation rate surface density. These trends could be explained if the isotopic abundances are altered by fractionation; the sense of the trends also agrees with those expected for carbon and oxygen isotopic abundance variations due to selective enrichment by massive stars.

  13. A foraminiferal δ18O record covering the last 2,200 years

    Science.gov (United States)

    Taricco, Carla; Alessio, Silvia; Rubinetti, Sara; Vivaldo, Gianna; Mancuso, Salvatore

    2016-06-01

    Thanks to the precise core dating and the high sedimentation rate of the drilling site (Gallipoli Terrace, Ionian Sea) we were able to measure a foraminiferal δ18O series covering the last 2,200 years with a time resolution shorter than 4 years. In order to support the quality of this data-set we link the δ18O values measured in the foraminifera shells to temperature and salinity measurements available for the last thirty years covered by the core. Moreover, we describe in detail the dating procedures based on the presence of volcanic markers along the core and on the measurement of 210Pb and 137Cs activity in the most recent sediment layers. The high time resolution allows for detecting a δ18O decennial-scale oscillation, together with centennial and multicentennial components. Due to the dependence of foraminiferal δ18O on environmental conditions, these oscillations can provide information about temperature and salinity variations in past millennia. The strategic location of the drilling area makes this record a unique tool for climate and oceanographic studies of the Central Mediterranean.

  14. 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.

  15. Growth of 18O isotopically enriched ZnO nanorods by two novel VPT methods

    Science.gov (United States)

    Gray, Ciarán; Trefflich, Lukas; Röder, Robert; Ronning, Carsten; Henry, Martin O.; McGlynn, Enda

    2017-02-01

    We have developed two novel vapour phase transport methods to grow ZnO nanorod arrays isotopically enriched with 18O. Firstly, a three-step process used to grow natural and Zn-enriched ZnO nanorods has been further modified, by replacing the atmospheric O2 with enriched 18O2, in order to grow 18O-enriched ZnO nanorods using this vapour-solid method on chemical bath deposited buffer layers. In addition, 18O-enriched ZnO nanorods were successfully grown using 18O isotopically enriched ZnO source powders in a vapour-liquid-solid growth method. Scanning electron microscopy studies confirmed the success of both growth methods in terms of nanorod morphology, although in the case of the vapour-liquid-solid samples, the nanorods' c-axes were not vertically aligned due to the use of a non-epitaxial substrate. Raman and PL studies indicated clearly that O-enrichment was successful in both cases, although the results indicate that the enrichment is at a lower level in our samples compared to previous reports with the same nominal enrichment levels. The results of our studies also allow us to comment on both levels of enrichment achieved and on novel effects of the high temperature growth environment on the nanorod growth, as well as suggesting possible mechanisms for such effects. Very narrow photoluminescence line widths, far narrower than those reported previously in the literature for isotopically enriched bulk ZnO, are seen in both the vapour-solid and vapour-liquid-solid nanorod samples demonstrating their excellent optical quality and their potential for use in detailed optical studies of defects and impurities using low temperature photoluminescence.

  16. 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.

  17. 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.

  18. 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

  19. 18O Labeling of Chlorophyll d in Acaryochloris marina Reveals That Chlorophyll a and Molecular Oxygen Are Precursors*

    Science.gov (United States)

    Schliep, Martin; Crossett, Ben; Willows, Robert D.; Chen, Min

    2010-01-01

    The cyanobacterium Acaryochloris marina was cultured in the presence of either H218O or 18O2, and the newly synthesized chlorophylls (Chl a and Chl d) were isolated using high performance liquid chromatography and analyzed by mass spectroscopy. In the presence of H218O, newly synthesized Chl a and d, both incorporated up to four isotopic 18O atoms. Time course H218O labeling experiments showed incorporation of isotopic 18O atoms originating from H218O into Chl a, with over 90% of Chl a 18O-labeled at 48 h. The incorporation of isotopic 18O atoms into Chl d upon incubation in H218O was slower compared with Chl a with ∼50% 18O-labeled Chl d at 115 h. The rapid turnover of newly synthesized Chl a suggested that Chl a is the direct biosynthetic precursor of Chl d. In the presence of 18O2 gas, one isotopic 18O atom was incorporated into Chl a with approximately the same kinetic incorporation rate observed in the H218O labeling experiment, reaching over 90% labeling intensity at 48 h. The incorporation of two isotopic 18O atoms derived from molecular oxygen (18O2) was observed in the extracted Chl d, and the percentage of double isotopic 18O-labeled Chl d increased in parallel with the decrease of non-isotopic-labeled Chl d. This clearly indicated that the oxygen atom in the C31-formyl group of Chl d is derived from dioxygen via an oxygenase-type reaction mechanism. PMID:20610399

  20. Leaf morphological effects predict effective path length and enrichment of 18O in leaf water of different Eucalyptus species

    Science.gov (United States)

    Kahmen, A.; Merchant, A.; Callister, A.; Dawson, T. E.; Arndt, S. K.

    2006-12-01

    Stable isotopes have been a valuable tool to study water or carbon fluxes of plants and ecosystems. In particular oxygen isotopes (δ18O) in leaf water or plant organic material are now beginning to be established as a simple and integrative measure for plant - water relations. Current δ18O models, however, are still limited in their application to a broad range of different species and ecosystems. It remains for example unclear, if species-specific effects such as different leaf morphologies need to be included in the models for a precise understanding and prediction of δ18O signals. In a common garden experiment (Currency Creek Arboretum, South Australia), where over 900 different Eucalyptus species are cultivated in four replicates, we tested effects of leaf morphology and anatomy on δ18O signals in leaf water of 25 different species. In particular, we determined for all species enrichment in 18O of mean lamina leaf water above source water (Δ18O) as related to leaf physiology as well as leaf thickness, leaf area, specific leaf area and weight and selected anatomical properties. Our data revealed that diurnal Δ18O in leaf water at steady state was significantly different among the investigated species and with differences up to 10% at midday. Fitting factors (effective path length) of leaf water Δ18O models were also significantly different among the investigated species and were highly affected by species-specific morphological parameters. For example, leaf area explained a high percentage of the differences in effective path length observed among the investigated species. Our data suggest that leaf water δ18O can act as powerful tool to estimate plant - water relations in comparative studies but that additional leaf morphological parameters need to be considered in existing δ18O models for a better interpretation of the observed δ18O signals.

  1. 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

  2. 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

  3. 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.

  4. Characterization of surface and ground water δ18O seasonal variation and its use for estimating groundwater residence times

    Science.gov (United States)

    Reddy, Michael M.; Schuster, Paul; Kendall, Carol; Reddy, Micaela B.

    2006-01-01

    18O is an ideal tracer for characterizing hydrological processes because it can be reliably measured in several watershed hydrological compartments. Here, we present multiyear isotopic data, i.e. 18O variations (δ18O), for precipitation inputs, surface water and groundwater in the Shingobee River Headwaters Area (SRHA), a well-instrumented research catchment in north-central Minnesota. SRHA surface waters exhibit δ18O seasonal variations similar to those of groundwaters, and seasonal δ18O variations plotted versus time fit seasonal sine functions. These seasonal δ18O variations were interpreted to estimate surface water and groundwater mean residence times (MRTs) at sampling locations near topographically closed-basin lakes. MRT variations of about 1 to 16 years have been estimated over an area covering about 9 km2 from the basin boundary to the most downgradient well. Estimated MRT error (±0·3 to ±0·7 years) is small for short MRTs and is much larger (±10 years) for a well with an MRT (16 years) near the limit of the method. Groundwater transit time estimates based on Darcy's law, tritium content, and the seasonal δ18O amplitude approach appear to be consistent within the limits of each method. The results from this study suggest that use of the δ18O seasonal variation method to determine MRTs can help assess groundwater recharge areas in small headwaters catchments.

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

    Science.gov (United States)

    Schollaen, K.; Karamperidou, C.; Krusic, P.; Cook, E.; Helle, G.

    2015-10-01

    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, as well as the potential of palaeoclimate proxy records from appropriately selected tropical regions for reconstructing past variability of. ENSO flavors.

  6. 13C-18O isotope signatures and ‘clumped isotope’ thermometry in foraminifera and coccoliths

    Science.gov (United States)

    Tripati, Aradhna K.; Eagle, Robert A.; Thiagarajan, Nivedita; Gagnon, Alexander C.; Bauch, Henning; Halloran, Paul R.; Eiler, John M.

    2010-10-01

    Accurate constraints on past ocean temperatures and compositions are critical for documenting climate change and resolving its causes. Most proxies for temperature are not thermodynamically based, appear to be subject to biological processes, require regional calibrations, and/or are influenced by fluid composition. As a result, their interpretation becomes uncertain when they are applied in settings not necessarily resembling those in which they were empirically calibrated. Independent proxies for past temperature could provide an important means of testing and/or expanding on existing reconstructions. Here we report measurements of abundances of stable isotopologues of calcitic and aragonitic benthic and planktic foraminifera and coccoliths, relate those abundances to independently estimated growth temperatures, and discuss the possible scope of equilibrium and kinetic isotope effects. The proportions of 13C- 18O bonds in these samples exhibits a temperature dependence that is generally similar to that previously been reported for inorganic calcite and other biologically precipitated carbonate-containing minerals (apatite from fish, reptile, and mammal teeth; calcitic brachiopods and molluscs; aragonitic coral and mollusks). Most species that exhibit non-equilibrium 18O/ 16O (δ 18O) and 13C/ 12C (δ 13C) ratios are characterized by 13C- 18O bond abundances that are similar to inorganic calcite and are generally indistinguishable from apparent equilibrium, with possible exceptions among benthic foraminiferal samples from the Arctic Ocean where temperatures are near-freezing. Observed isotope ratios in biogenic carbonates can be explained if carbonate minerals generally preserve a state of ordering that reflects the extent of isotopic equilibration of the dissolved inorganic carbon species.

  7. Letter: Observation of the 16O/18O exchange during electrospray ionization.

    Science.gov (United States)

    Kostyukevich, Yury; Kononikhin, Alexey; Popov, Igor; Nikolaev, Eugene

    2015-01-01

    Isotopic exchange approach coupled to high-resolution mass spectrometry has become the power analytical approach for a wide range of analytical and bioanalyticall applications. Considerable efforts have been dedicated to developing fast exchange techniques directly in the ionization source. But all such methods are limited to the hydrogen/deuterium exchange approaches. In this paper we demonstrate that certain types of oxygen atoms can also be exchanged for (18)O on the time scale of the ionization process. Using HIO(3) and NaIO(4) and by infusing the heavy water H(2)(18)O in the ESI source we have demonstrated that it is possible to obtain a high level of oxygen exchange. It was observed that the rate of this exchange depends to a large extent on the temperature of the desolvating capillary of the mass spectrometer. Several other species, such as peptides, oligonucleotides and low weight organic molecules, were subjected to in-ESI (16)O/(18)O exchange but the exchange was not observed.

  8. NanoSIMS50 analyses of Ar/18O2 plasma-treated Escherichia coli bacteria

    Science.gov (United States)

    Clément, F.; Lecoq, E.; Duday, D.; Belmonte, T.; Audinot, J.-N.; Lentzen, E.; Penny, C.; Cauchie, H.-M.; Choquet, P.

    2011-11-01

    Reactive oxygen species (ROS) can be produced by electrical discharges and can be transported in uncharged regions by gas flows, in the so-called afterglows. These species are well known to have bactericidal effects but interaction mechanisms that occur with living micro-organisms remain misunderstood. In order to better understand these interactions, new analysis approaches are necessary. High-lateral-resolution secondary ion mass spectrometry (NanoSIMS) is one of the most promising ways of retrieving additional information on bacteria plasma inactivation mechanisms by combining isotopic imaging of plasma-treated bacteria and the use of 18O2 as process gas. Indeed, this technology combines a lateral resolution of a few tens of nanometres that is sufficient to image the interior of bacteria, and a high mass resolution allowing detection of isotopes present in low quantities (a few ppm or lower) within the bacteria. The present paper deals with Ar-18O2 (2%) plasma treatment, through low-pressure microwave late afterglows, of Escherichia coli bacteria and their elemental and isotopic imaging by NanoSIMS. E. coli bacteria have been exposed to this reactive medium for varying treatment duration while keeping all other parameters unchanged. Our main goal is to determine whether the quantity of 18O fixed in treated bacteria and the NanoSIMS50 lateral resolution are sufficient to give additional information on E. coli bacteria-plasma interaction.

  9. 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.

  10. 13CO, C18O, and CS Observations toward Massive Dense Cores

    Science.gov (United States)

    Ao, Yiping; Yang, Ji; Sunada, Kazuyoshi

    2004-10-01

    We present results of 13CO J=1-0, C18O J=1-0, and CS J=2-1 map observations toward 10 massive star-forming regions selected from the previous CO line survey of cold IRAS sources along the Galactic plane. CS line emission was detected from 9 out of 10 sources, and 13CO line emission was detected in all sources. C18O J=1-0 line emission was detected in only three sources. Physical parameters are derived for the detected sources. The 13CO and C18O data support the idea that gradual dissipation of the internal turbulence leads to formation of denser cores and subsequent star formation. There is no apparent relationship between the CS abundance and the CO temperature. The ratios of LIR to MLTE vary by no more than a factor of 3 for the CS cores and by nearly 1 order of magnitude for the 13CO cores. This indicates that star formation is determined by the gas with high volume density and does not depend on the mass of the cloud. We find that the star formation rate per unit mass is nearly constant in the dense cores. Divided into two subgroups, ``low'' and ``high,'' by their FIR color indexes, the low sources are in an earlier stage than the high sources, based on the high sources' association with H2O masers.

  11. 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.

  12. 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

  13. δ18O records in water vapor and an ice core from the eastern Pamir Plateau: Implications for paleoclimate reconstructions

    Science.gov (United States)

    Yu, Wusheng; Tian, Lide; Risi, Camille; Yao, Tandong; Ma, Yaoming; Zhao, Huabiao; Zhu, Haifeng; He, You; Xu, Baiqing; Zhang, Hongbo; Qu, Dongmei

    2016-12-01

    This study is the first to examine δ18O in daily water vapor at Taxkorgan on the eastern Pamir Plateau. The results show that changes in observed and simulated δ18O values in water vapor/precipitation at the event scale (using a LMDZ-iso model) were mainly affected by temperature. The influences of humidity, precipitation amount, and different moisture sources, such as the westerlies, local evaporated moisture, and polar air masses, on δ18O values are comparatively weak. The combination of the δ18O record from the Muztagata ice core, 58 km away from the study area, and the LMDZ-iso simulated annual δ18O pattern in precipitation at Taxkorgan also demonstrated that temperature, and particularly the temperature of the regions over which the southern branch of the westerlies flows, is the most important factor controlling δ18O variations. The results from this study area, which is dominated by the westerlies throughout the year, are markedly different from those derived from parts of the Tibetan Plateau that are dominated by the combined influences of the westerlies in winter and the Indian monsoon in summer. The results suggested that the eastern Pamir Plateau is an ideal location to reconstruct past temperature variations and that the δ18O records preserved in ice cores from the region are a suitable and robust proxy for temperature.

  14. East China Sea δ18O Record Detects Millennial-Scale Changes in the East Asian Summer Monsoon

    Science.gov (United States)

    Gleeman, E.; Clemens, S. C.; Lawman, A. E.; Kubota, Y.; Holbourn, A. E.; Martin, A.

    2015-12-01

    The East Asian Summer Monsoon (EASM) brings heavy summer rainfall to some of Asia's most densely-populated areas, impacting agricultural production and water resources. Sediment cores were recovered from International Ocean Drilling Program Site U1429 in the East China Sea (31° 37.04' N, 128° 59.50' E, 732 mbsl). This location receives runoff from the Yangtze River, which serves as a major drainage system for monsoon-induced precipitation. Hence, the δ18O record of planktonic foraminifera at Site U1429 reflects changes in regional, monsoon-driven salinity. The top 100 meters of core at Site U1429 were sampled at a preliminary resolution of 15 cm and processed to isolate the planktonic foraminifer Globigerinoides ruber for δ18O mass spectrometry analyses. Abrupt, millennial-scale regional climate variability in the EASM and its linkage to orbital forcings have been reconstructed using stratigraphic analysis of δ18O. The sub-orbital scale structure of the δ18O record over the past 400 kyr matches the structures of both the composite speleothem δ18O from eastern China (Sanbao and Hulu caves) and the planktonic δ18O record from northern South China Sea Site 1146. The similarities between these δ18O records indicate a strong regional response to monsoon forcing. Removal of the temperature component of the δ18O signal by using Mg/Ca (G. ruber) paleothermometry will provide a record of changes in the δ18O composition of seawater in response to Yangtze River runoff.

  15. A high-resolution late Holocene speleothem record from Kaite Cave, northern Spain: δ18O variability and possible causes

    OpenAIRE

    Domínguez Villar, David; Wang, Xianfeng; Cheng, Hai; Martín Chivelet, Javier; Edwards, R. Lawrence

    2008-01-01

    A high-resolution calcite oxygen stable isotopic (δ18O) record, covering the past 4000 years, was obtained from Kaite Cave, northern Spain. The record has a mean δ18O value of -6.25% VPDB and a range of 2%. Spectral analysis of the d18O data shows significant periodicities of 2400–1900, 600, 150, 27, and 22 years. The amplitudes during these periods range from 0.2% to 2%. Factors controlling the isotopic ratio in the speleothem were evaluated. The calcite is most likely precipitated ...

  16. Probabilistic sequence alignment of Late Pleistocene benthic δ18O data

    Science.gov (United States)

    Lawrence, C.; Lin, L.; Lisiecki, L. E.; Stern, J.

    2013-12-01

    The stratigraphic alignment of ocean sediment cores plays a vital role in paleoceanographic research because it is used to develop mutually consistent age models for climate proxies measured in these cores. The most common proxy used for alignment is the The stratigraphic alignment of ocean sediment cores plays a vital role in paleoceanographic research because it is used to develop mutually consistent age models for climate proxies measured in these cores. The most common proxy used for alignment is the δ18O of calcite from benthic or planktonic foraminifera because a large fraction of δ18O variance derives from the global signal of ice volume. To date, alignment has been performed either by manual, qualitative comparison or by deterministic algorithms (Martinson, Pisias et al. Quat. Res. 27 1987; Lisiecki and Lisiecki Paleoceanography 17, 2002; Huybers and Wunsch, Paleoceanography 19, 2004). Here we present a probabilistic sequence alignment algorithm which provides 95% confidence bands for the alignment of pairs of benthic δ18O records. The probabilistic algorithm presented here is based on a hidden Markov model (HMM) (Levinson, Rabiner et al. Bell Systems Technical Journal, 62,1983) similar to those that have been used extensively to align DNA and protein sequences (Durbin, Eddy et al. Biological Sequence Analysis, Ch. 4, 1998). However, here the need to the alignment of sequences stems from expansion and/or contraction in the records due to changes in sedimentation rates rather than the insertion or deletion of residues. Transition probabilities that are used in this HMM to model changes in sedimentation rates are based on radiocarbon estimates of sedimentation rates. The probabilistic algorithm considers all possible alignments with these predefined sedimentation rates. Exact calculations are completed using dynamic programming recursions. The algorithm yields the probability distributions of the age at each point in the record, which are probabilistically

  17. {sup 6}Li({sup 18}O, {sup 17}O){sup 7}Li reaction and comparison of {sup 6, 7}Li + {sup 16, 17, 18}O potentials

    Energy Technology Data Exchange (ETDEWEB)

    Rudchik, A.T., E-mail: rudchik@kinr.kiev.ua [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Chercas, K.A. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Kemper, K.W. [Physics Department, Florida State University, Tallahassee, FL 32306-4350 (United States); Rudchik, A.A. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Kliczewski, S. [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland); Koshchy, E.I. [Kharkiv National University, pl. Svobody 4, 61077 Kharkiv (Ukraine); Rusek, K. [National Center for Nuclear Reseaches, ul. Hoża 69, PL-00-681 Warsaw (Poland); Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Mezhevych, S.Yu.; Ponkratenko, O.A.; Pirnak, Val.M. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Plujko, V.A. [Taras Shevchenko National University, ul. Volodymyrska 64, 01033 Kyiv (Ukraine); Choiński, J. [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Czech, B.; Siudak, R.; Szczurek, A. [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland)

    2014-07-15

    Angular distributions of the {sup 6}Li({sup 18}O, {sup 17}O){sup 7}Li reaction were measured at E{sub lab}({sup 18}O)=114 MeV for ground and excited states of the exit channel nuclei for the first time. The data were analyzed within the coupled-reaction-channels method (CRC). The {sup 6}Li + {sup 18}O elastic and inelastic scattering channels as well as simplest one- and two-step reactions were included in the coupled-reaction-channels scheme. The {sup 7}Li + {sup 17}O potential was deduced by fitting CRC calculations to the reaction data. The spectroscopic amplitudes for single nucleon and nuclear cluster configurations were calculated within the translationally invariant shell model. Isotopic differences of the {sup 7}Li + {sup 16, 17, 18}O and {sup 7, 8}Li + {sup 17}O potentials and the reaction mechanisms were studied.

  18. {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.

  19. 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

  20. 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

  1. A Review of Climatic Controls on δ18o in Precipitation over the Tibetan Plateau: Observations and Simulations

    Science.gov (United States)

    Yao, T.; Masson-Delmotte, V.; Gao, J.; Risi, C. M.

    2014-12-01

    Located at the convergence of air masses between the westerlies and monsoon, the Tibetan Plateau (TP) undergoes complex water cycle processes, which need to be documented and understood through a combination of variant methodologies. The stable oxygen isotope ratio (δ18O) in precipitation is an integrated tracer of the atmospheric processes and has been used worldwide. Since the 1990s, an intensive effort has been dedicated to studying precipitation isotopic composition at more than 20 stations in the TP. Based on these observations, we establish a database of precipitation δ18O and use different models to evaluate the climatic drivers of present-day precipitation δ18O over the TP. The spatial and temporal patterns of precipitation δ18O and their relationships with temperature and precipitation reveal three distinct domains, respectively associated with the influence of the westerlies (Northern TP), Indian monsoon (Southern TP) and transition in between. The seasonal patterns of precipitation δ18O are diverse in different domains. High-resolution atmospheric models equipped with stable isotopes capture the spatial and temporal patterns of precipitation δ18O and their relationships with moisture transport from the westerlies and Indian monsoon. Only in the westerlies domain are atmospheric models able to represent qualitatively and quantitatively the relationships between climate and precipitation δ18O. More significant temperature effect exists when either the westerlies or Indian monsoon is the sole dominant atmospheric process. The observed and simulated altitude-δ18O relationships strongly depend on the season and the domain (monsoon or westerlies). Our results have crucial implications for the interpretation of the abundant stable isotope information derived from natural climatic archives over the TP such as ice cores, lake sediments or tree rings, and for the application of atmospheric simulations to quantifying paleo-climate and paleo

  2. Mg/Ca and δ18O in the calcite of benthic foraminifera: does size matter?

    Science.gov (United States)

    de Nooijer, Lennart; Bijma, Jelle; -Jan Reichart, Gert; Hathorne, Ed

    2010-05-01

    Mg/Ca and del-18O are popular proxies for past sea water temperatures, ice volume and, together, salinity. The biological control that foraminifera have over calcification results in precipitation of calcium carbonate that has an isotope and element composition that is very different from those of inorganically precipitated calcium carbonates. Indications for an effect of ontogeny (i.e. size of a specimen) on the fractionation of oxygen isotopes are contradictory, while for the incorporation of most (trace) elements, data are lacking. The causes of size-based variability in element incorporation and isotope fractionation need to be understood and quantified in order to reliably use them as paleoproxies. In this study, we present Mg/Ca and oxygen isotope data from cultured specimens of the benthic foraminifer Ammonia tepida. When asexual reproduction takes place in this species, 50-300 genetically identical juveniles (i.e. clones) are produced. These juveniles are cultured at constant temperature, carbonate chemistry, salinity, etc to determine inter- and intra-specimen variability in Mg/Ca, Ba/Ca and Sr/Ca. From the same groups of clones, del-18O was determined from specimens with different sizes. Results show that the variability differs greatly between the analysed elements (e.g. relatively constant for Sr and Ba, variable for Mg) and isotopes, underscoring the need for a biological understanding of foraminiferal calcification pathways.

  3. Optimization of {sup 18}O measurement using NRA for studies of isotopic content in fossil meteorites

    Energy Technology Data Exchange (ETDEWEB)

    Borysiuk, M., E-mail: maciek.borysiuk@pixe.lth.se [Division of Nuclear Physics, Department of Physics, Lund University, Box 118, SE-221 00 Lund (Sweden); Kristiansson, P.; Arteaga-Marrero, N.; Elfman, M.; Golubev, P.; Nilsson, E.J.C.; Nilsson, C.; Pallon, J.; Salim, N. [Division of Nuclear Physics, Department of Physics, Lund University, Box 118, SE-221 00 Lund (Sweden)

    2011-10-15

    In this work, we discuss the possibility of a new approach to measuring oxygen isotope ratios in fossil meteorite samples, specifically one based on nuclear reaction analysis (NRA). Variations of oxygen ratios within meteoritic chromite grains can help to determine the type of meteorite to which the grains originally belonged. In this work, we have evaluated the possibility to use the reaction {sup 18}O(p, {alpha}){sup 15}N just above the 846 keV resonance to estimate the relative oxygen-18 content in a number of test samples. Another technique has to be employed for oxygen-16 measurements. A large area segmented silicon detector is used to detect the produced {alpha} particles. Results of the experimental {sup 18}O measurements for a number of samples including four extraterrestrial chromite grains are presented and compared with SIMNRA simulations. The advantage of a segmented silicon detector in the form of inherent pile-up suppression can be clearly seen in the current work.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Nonstatistical behavior of reactive scattering in the (18)O+(32)O(2) isotope exchange reaction.

    Science.gov (United States)

    Wyngarden, Annalise L Van; Mar, Kathleen A; Boering, Kristie A; Lin, Jim J; Lee, Yuan T; Lin, Shi-Ying; Guo, Hua; Lendvay, Gyorgy

    2007-03-14

    The recombination of oxygen atoms with oxygen molecules to form ozone exhibits several strange chemical characteristics, including unusually large differences in formation rate coefficients when different isotopes of oxygen participate. Purely statistical chemical reaction rate theories cannot describe these isotope effects, suggesting that reaction dynamics must play an important role. We investigated the dynamics of the 18O + 32O2 --> O3(*) --> 16O + 34O2 isotope exchange reaction (which proceeds on the same potential energy surface as ozone formation) using crossed atomic and molecular beams at a collision energy of 7.3 kcal mol(-1), providing the first direct experimental evidence that the dissociation of excited ozone exhibits significant nonstatistical behavior. These results are compared with quantum statistical and quasi-classical trajectory calculations in order to gain insight into the potential energy surface and the dynamics of ozone formation.

  15. 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).

  16. 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.

  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. 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.

  19. 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.

  20. A C$^{18}$O study of the origin of the power-law nature in the IMF

    CERN Document Server

    Ikeda, Norio

    2009-01-01

    We have performed C$^{18}$O ($J$=1--0) mapping observations of a $20'\\times20'$ area of the OMC-1 region in the Orion A cloud. We identified 65 C$^{18}$O cores, which have mean radius, velocity width in FWHM, and LTE mass of 0.18$\\pm$0.03 pc, 0.40$\\pm$0.15 km s$^{-1}$, and 7.2$\\pm$4.5 $M_\\odot$, respectively. All the cores are most likely to be gravitationally bound by considering the uncertainty in the C$^{18}$O abundance. We derived a C$^{18}$O core mass function, which shows a power-law-like behavior above 5 $M_\\odot$. The best-fit power-law index of $-2.3\\pm0.3$ is consistent with those of the dense core mass functions and the stellar initial mass function (IMF) previously derived in the OMC-1 region. This agreement strongly suggests that the power-law form of the IMF has been already determined at the density of $\\sim10^{3}$ cm$^{-3}$, traced by the C$^{18}$O ($J$=1--0) line.

  1. 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.

  2. Stable oxygen isotopes (delta18(O)) in Austrocedrus chilensis tree rings reflect climate variability in northwestern Patagonia, Argentina.

    Science.gov (United States)

    Roig, F A; Siegwolf, R; Boninsegna, J A

    2006-11-01

    The stable oxygen isotope (delta (18)O) composition of Austrocedrus chilensis (D. Don) Endl. (Cupressaceae) tree rings potentially provide retrospective views of changes in environment and climate in the semi-arid lands of Patagonia. We report the development of the first annually resolved delta (18)O tree-ring chronology obtained from natural forests of the foothills of the northwestern Patagonian Andes. The isotope record spans between 1890 and 1994 AD. We explore the probable links between this record and the climate of the region. Air temperatures during summer conditions are significantly, but not strongly, inversely correlated with annual delta (18)O values from Austrocedrus tree rings. The strongest correlations are between the southern oscillation index (SOI) and the tree rings. The existence of millennial-age Austrocedrus trees in northern Patagonia provides interesting possibilities for examining these climate-related isotopic signals over most of the last 1,000 years.

  3. Humidity Effect and Its Influence on the Seasonal Distribution of Precipitation δ18O in Monsoon Regions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xinping; LIU Jingmiao; HE Yuanqing; TIAN Lide; YAO Tandong

    2005-01-01

    The humidity effect, namely the markedly positive correlation between the stable isotopic ratio in precipitation and the dew-point deficit △Td in the atmosphere, is put forward firstly and the relationships between the δ18O in precipitation and △Td are analyzed for the Urumqi and Kunming stations, which have completely different climatic characteristics. Although the seasonal variations in δ18O and △Td exhibit differences between the two stations, their humidity effect is notable. The correlation coefficient and its confidence level of the humidity effect are higher than those of the amount effect at Kunming, showing the marked influence of the humidity conditions in the atmosphere on stable isotopes in precipitation.Using a kinetic model for stable isotopic fractionation, and according to the seasonal distribution of meanmonthly temperature at 500 hPa at Kunming, the variations of the δ18O in condensate in cloud aresimulated. A very good agreement between the seasonal variations of the simulated mean δ18O and themean monthly temperature at 500 hPa is obtained, showing that the oxygen stable isotope in condensateof cloud experiences a temperature effect. Such a result is markedly different from the amount effect atthe ground. Based on the simulations of seasonal variations of δ18O in falling raindrops, it can be foundthat, in the dry season from November to April, the increasing trend with falling distance of δ18O in fallingraindrops corresponds remarkably to the great ATd, showing a strong evaporation enrichment function infalling raindrops; however, in the wet season from May to October, the δ18O in falling raindrops displaysan unapparent increase corresponding to the small ATd, except in May. By comparing the simulated meanδ18O at the ground with the actual monthly δ18O in precipitation, we see distinctly that the two monthlyδ18O variations agree very well. On average, the δ18O values are relatively lower because of the highlymoist air, heavy

  4. 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.

  5. A new mechanism for the two-step δ18O signal at the Eocene-Oligocene boundary

    Directory of Open Access Journals (Sweden)

    A. S. von der Heydt

    2011-03-01

    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 suggestive of a greenhouse gas control on climate. Previous modelling 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 considered changes in the ocean circulation only regionally, or indirectly through the oceanic heat transport. The potential role of global changes in ocean circulation in the E-O transition has not been addressed yet. 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 record reflects 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. The second step in the δ18O profile occurs due to a rapid glaciation of the Antarctic continent. This new mechanism is a robust outcome of our model and is qualitatively in close agreement with proxy data.

  6. Coupled-channels analysis of 800 MeV polarized proton inelastic scattering from /sup 18/O

    Energy Technology Data Exchange (ETDEWEB)

    Glashausser, C.; De Swiniarski, R.; Jones, K.; Nanda, S. (Rutgers - the State Univ., New Brunswick, NJ (USA)); Baker, F.T.; Grimm, M.; Penumetcha, V.; Scott, A. (Georgia Univ., Athens (USA)); Adams, G.; Igo, G. (California Univ., Los Angeles (USA))

    1982-10-14

    Differential cross sections and analyzing powers have been measured for the /sup 18/O(p vector, p')/sup 18/O reaction at 800 MeV. A coupled-channels analysis of the 0/sub 1//sup +/, 2/sub 1//sup +/, and 4/sub 2//sup +/ data yields good agreement with a rotational model description with a large ..beta../sub 4/ deformation. The effects of channel coupling are large. The angular distributions of Asub(y) are reproduced well only with a full Thomas spin-orbit deformation approximately equal to the central deformation.

  7. Surface Oxidation and Fast 18O Implant Diffusion in Nanostructured Layers of Ti-6Al-4V Alloy

    OpenAIRE

    S.M. Duvanov; A.G. Balogh

    2015-01-01

    A formation of the near surface barrier composite oxide film and two-stage 18O implant diffusion in modified layers of Ti-6Al-4V alloy were observed in the present work. Fast and super fast regimes occur during second stage of the diffusion. Sample modification was performed using ion implantation and subsequent thermal annealing in ultra-high vacuum (UHV) atmosphere. Parameters of ion implantation are the following: 18O+ ion energy of 30 keV; fluence of 3 × 1017 ion/cm2; RT. Post-implantatio...

  8. Combining hydrometry observations with 2H and 18O tracers in Molteno formations, South Africa

    Science.gov (United States)

    Lorentz, S.; Gqiba, D.; Verhagen, B.

    2003-04-01

    The definition of flow generation mechanisms at the hillslope and small catchment scale (less than 10 sq. km) is important in quantifying runoff generation, low flow contributions as well as the consequences of land use change. In this paper, a research catchment on a Molteno formation in the northern Eastern Cape Province is described. Flow generation mechanisms on the hillslopes and nested sub-catchments have been studied for the past five years, prior to a change in land use to forestation. Observations of overland flow, soil water, perched saturated groundwater, rainfall and runoff are combined with 2H and 18O tracer signatures from these sources. These combined observations are applied to hillslope and catchment process simulations in order to quantify the residence times and fluxes of the sources of runoff. Analyses of intense rainfall events reveal that the dominant source of streamflow is from near-surface, macro-pore layers during these events. Deeper groundwater sources contribute to runoff during low intensity events.

  9. A New Look at 29Al and 27Mg from the 18O + 14C Reaction

    Science.gov (United States)

    Tabor, Samuel; Dungan, Rutger; Volya, Alexander; Tripathi, Vandana; Abromeit, Brittany; Caussyn, David; Kravvaris, Konstantinos; Lubna, Rebeka; Tai, Pei-Luan

    2016-09-01

    It was possible to compare moderately high-spin states in a nearby pair of odd proton and odd neutron s-d shell nuclei by observing proton-gamma-gamma or alpha-gamma-gamma coincidences, respectively, following the fusion of long-lived radioactive 14C with neutron-rich 18O at a beam energy of 40 MeV using the FSU gamma detector array with digital data acquisition. Eight new states were seen in 29Al, all of which decay directly or indirectly to the 9/2 + level, the highest previously known spin in 29Al. Some of the new states form a very likely yrast M1 decay sequence from (15/2 +) down to the 5/2 + ground state. The new states are relatively well described by pure s-d shell model calculations using the USDA interaction. By contrast the 4 new states found in 27Mg are divided between positive and negative parities reaching up to (13/2 +) and (11/2-). Radiative decays of neutron unbound states in 27Mg will be discussed. Supported in part by NSF Grant No. 1401574.

  10. 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.

  11. 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.

  12. 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.

  13. Clumpy filaments of the Chamaeleon I cloud: C18O mapping with the SEST

    CERN Document Server

    Haikala, L K; Mattila, K; Toriseva, M

    2004-01-01

    The Chamaeleon I dark cloud (Cha I} has been mapped in C18O J=1-0 with an angular resolution of 1 arcmin using the SEST telescope. The large scale structures previously observed with lower spatial resolution in the cloud turn into a network of clumpy filaments. The automatic Clumpfind routine developed by Williams et al. 1994 is used to identify individual clumps in a consistent way. Altogether 71 clumps were found and the total mass of these clumps is 230 Mo. The dense 'cores' detected with the NANTEN telescope (Mizuno et al. 1999) and the very cold cores detected in the ISOPHOT serendipity survey (Toth et al. 2000) form parts of these filaments but decompose into numerous 'clumps' The filaments are preferentially oriented at right angles to the large-scale magnetic field in the region. We discuss the cloud structure, the physical characteristics of the clumps and the distribution of young stars. The observed clump mass spectrum is compared with the predictions of the turbulent fragmentation model of Padoan ...

  14. 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...

  15. 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

  16. 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.

  17. 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...

  18. delta13C and delta18O trends across overstory environments in whole foliage and cellulose of three Pinus species.

    Science.gov (United States)

    Powers, Matthew D; Pregitzer, Kurt S; Palik, Brian J

    2008-09-01

    Stable isotope ratios of carbon (delta(13)C) and oxygen (delta(18)O) are increasingly used to investigate environmental influences on plant physiology. Cellulose is often isolated for isotopic studies, but some authors have questioned the value of this process. We studied trends in delta(13)C and delta(18)O of whole foliage and holocellulose from seedlings of three Pinus species across three overstory environments to evaluate the benefits of holocellulose extraction in the context of a traditional ecological experiment. Both tissue types showed increasing delta(13)C from closed-canopy controls to thinned plots to 0.3 ha canopy gaps, and no change in delta(18)O between overstory environments. delta(13)C of P. resinosa and P. strobus was greater than delta(13)C of P. banksiana in whole foliage and holocellulose samples, and there were no differences in delta(18)O associated with species in either tissue type. Our results suggest whole foliage and holocellulose provide similar information about isotopic trends across broad environmental gradients and between species, but holocellulose may be better suited for studying differences in stable isotope composition between multiple species across several treatments.

  19. 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.

  20. 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

  1. 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

  2. Stable isotope time-series in mammalian teeth: In situ δ18O from the innermost enamel layer

    Science.gov (United States)

    Blumenthal, Scott A.; Cerling, Thure E.; Chritz, Kendra L.; Bromage, Timothy G.; Kozdon, Reinhard; Valley, John W.

    2014-01-01

    Stable carbon and oxygen isotope ratios in mammalian tooth enamel are commonly used to understand the diets and environments of modern and fossil animals. Isotope variation during the period of enamel formation can be recovered by intra-tooth microsampling along the direction of growth. However, conventional sampling of the enamel surface provides highly time-averaged records in part due to amelogenesis. We use backscattered electron imaging in the scanning electron microscope (BSE-SEM) to evaluate enamel mineralization in developing teeth from one rodent and two ungulates. Gray levels from BSE-SEM images suggest that the innermost enamel layer, <20 μm from the enamel-dentine junction, is highly mineralized early in enamel maturation and therefore may record a less attenuated isotopic signal than other layers. We sampled the right maxillary incisor from a woodrat subjected to an experimentally induced water-switch during the period of tooth development, and demonstrate that secondary ion mass spectrometry (SIMS) can be used to obtain δ18O values with 4-5-μm spots from mammalian tooth enamel. We also demonstrate that SIMS can be used to discretely sample the innermost enamel layer, which is too narrow for conventional microdrilling or laser ablation. An abrupt δ18O switch of 16.0‰ was captured in breath CO2, a proxy for body water, while a laser ablation enamel surface intra-tooth profile of the left incisor captured a δ18O range of 12.1‰. The innermost enamel profile captured a δ18O range of 15.7‰, which approaches the full magnitude of δ18O variation in the input signal. This approach will likely be most beneficial in taxa such as large mammalian herbivores, whose teeth are characterized by less rapid mineralization and therefore greater attenuation of the enamel isotope signal.

  3. 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.

  4. 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

  5. Ab initio study on vibrational dipole moments of XH{sup +} molecular ions: X = {sup 24}Mg, {sup 40}Ca, {sup 64}Zn, {sup 88}Sr, {sup 114}Cd, {sup 138}Ba, {sup 174}Yb and {sup 202}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Minori; Hada, Masahiko [Department of Chemistry, Tokyo Metropolitan University, 1-1, Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); Kajita, Masatoshi [National Institute of Information and Communications Technology, Nukui-Kitamachi, Koganei, Tokyo 184-8795 (Japan); Moriwaki, Yoshiki, E-mail: minoria@tmu.ac.j [Department of Physics, University of Toyama, Gofuku, Toyama, 930-8555 (Japan)

    2010-12-28

    The vibrational matrix elements of electric dipole moments were theoretically estimated for the electronic ground state of XH{sup +} molecular ions (X = {sup 24}Mg, {sup 40}Ca, {sup 64}Zn, {sup 88}Sr, {sup 114}Cd, {sup 138}Ba, {sup 174}Yb and {sup 202}Hg) using the complete active space second-order perturbation theory method. Because of the large rotational constant and zero X-nuclear spin, these molecules are advantageous to be localized to a single (v, J, F) state, where v, J, F are quantum numbers of the vibrational, rotational and hyperfine states, respectively. The information of the dipole moments is very useful to discuss the period to localize the molecular ion to the (v, J, F) = (0, 0, 1/2) state and also the period to remain in this state, which is limited by the interaction with the black body radiation. The agreement of experimental and our theoretical spectroscopic constants ensures the accuracy of our results. Vibrational permanent and transition dipole moments were obtained with special care of accuracy in numerical integration. Spontaneous emission rates were calculated from the vibrational dipole moments and transition energies.

  6. 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

  7. 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.

  8. 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

  9. Using the Difference in 18O-enrichment in Pedogenic Carbonates and Freshwater Mollusk Shells as a Paleoaridity Proxy

    Science.gov (United States)

    Snell, K. E.; Koch, P. L.

    2008-12-01

    Aridity is an important climatic attribute, yet few proxies exist to reconstruct this parameter in the past. Here we present initial results from a study using the difference in oxygen isotope value between pedogenic carbonate and freshwater mollusk shells as a proxy for aridity. These carbonates record the oxygen isotope value of the soil water and surface water from which they precipitate, respectively, as well as temperature- dependent isotopic fractionation. Evaporation causes 18O-enrichment of water that may influence the isotopic composition of both reservoirs. Soil water is more susceptible to evaporative enrichment, however, whereas surface waters more closely track the oxygen isotope value of precipitation. If both carbonates are collected from the same region, and if we assume they form at essentially the same temperature, the 18O-enrichment of soil carbonate (soil water) relative to bivalve carbonate (surface water) may reflect aridity. Alternatively, it is possible to determine the temperature of formation of each carbonate independently using the carbonate clumped isotope thermometer (Ghosh, et al., 2006), and then to solve for the oxygen isotope value of soil and surface water. To test the premise that the extent of 18O-enrichment in pedogenic vs. bivalve carbonate will reflect aridity, we collected pedogenic carbonate, freshwater mollusk shells, and stream water samples across an aridity gradient in the midwestern United States (MN, IA, NE, SD). We discovered that while pedogenic carbonates apparently formed from soil waters that are 18O-enriched relative to meteoric water, samples from drier regions are not more strongly 18O-enriched than those from wetter regions. We will extend the study to include samples from even drier regions, such as those in the southwestern US, as 18O enrichment may only become highly pronounced under very arid conditions. While our results have not yet established this approach as a viable tool for reconstructing aridity

  10. Isotopic (18O) characteristics of weekly precipitation collected across the USA: an initial analysis with application to water source studies

    Science.gov (United States)

    Welker, J. M.

    2000-06-01

    A portion of the precipitation samples collected and stored by the National Atmospheric Deposition Program (NADP) are shown to be useful for analysis of isotopes in precipitation. The potential problems with evaporation are small based on deuterium excess analyses and comparisons with the Global Meteroic Water Line. Presented here are the 18O values of precipitation collected from nine NADP sites during 1989, 1990 and 1991. The trends in the isotopic (18O) characteristics of recent precipitation are in agreement with findings from previous International Atomic Energy Agency (IAEA) sites in the USA. The findings are also in agreement with several major isotope-environment relationships, further supporting the use of these samples for a modern global data base on the isotopes in precipitation being developed by IAEA, called GNIP (Global Network for Isotopes in Precipitation) and for use by research groups in the hydrological modelling, palaeoclimate and ecological communities.As expected, the average 18O values of precipitation that is derived from the Gulf of Mexico (-3) and from the Pacific North-west are isotopically distinct (-7). In addition, using the NADP network, isotopic depletion in the 18O values of precipitation in the range of 8 was observed from coastal to inland locations either in the Pacific North-west or along the east side of the Rocky Mountains, from Texas to Eastern Montana. In central USA, especially at high elevation, there is a strong seasonal variation in the 18O values of precipitation, differing by almost 25 between January and August, whereas at coastal locations the seasonal variation in the 18O values of precipitation was minimal. Comparisons between the average 18Colorado) and 046 (Nebraska) that are within the range of those reported earlier (029-07), although they are slightly lower, possibly owing to the large temperature variation between winter and summer in central USA. Further, the seasonal variation in the grasses typically

  11. Late quaternary climate, precipitation δ18O, and Indian monsoon variations over the Tibetan Plateau

    Science.gov (United States)

    Li, Jingmin; Ehlers, Todd A.; Werner, Martin; Mutz, Sebastian G.; Steger, Christian; Paeth, Heiko

    2017-01-01

    The Himalaya-Tibet orogen contains one of the largest modern topographic and climate gradients on Earth. Proxy data from the region provide a basis for understanding Tibetan Plateau paleo climate and paleo elevation reconstructions. Paleo climate model comparisons to proxy data compliment sparsely located data and can improve climate reconstructions. This study investigates temporal changes in precipitation, temperature and precipitation δ18O (δO18p) over the Himalaya-Tibet from the Last Glacial Maximum (LGM) to present. We conduct a series of atmospheric General Circulation Model (GCM, ECHAM5-wiso) experiments at discrete time slices including a Pre-industrial (PI, Pre-1850 AD), Mid Holocene (MH, 6 ka BP) and LGM (21 ka BP) simulations. Model predictions are compared with existing proxy records. Model results show muted climate changes across the plateau during the MH and larger changes occurring during the LGM. During the LGM surface temperatures are ∼ 2.0- 4.0 °C lower across the Himalaya and Tibet, and >5.0 °C lower at the northwest and northeast edge of the Tibetan Plateau. LGM mean annual precipitation is 200-600 mm/yr lower over on the Tibetan Plateau. Model and proxy data comparison shows a good agreement for the LGM, but large differences for the MH. Large differences are also present between MH proxy studies near each other. The precipitation weighted annual mean δ18Op lapse rate at the Himalaya is about 0.4 ‰ /km larger during the MH and 0.2 ‰ /km smaller during the LGM than during the PI. Finally, rainfall associated with the continental Indian monsoon (between 70°E-110°E and 10°N-30°N) is about 44% less in the LGM than during PI times. The LGM monsoon period is about one month shorter than in PI times. Taken together, these results document significant spatial and temporal changes in temperature, precipitation, and δ18Op over the last ∼21 ka. These changes are large enough to impact interpretations of proxy data and the intensity of

  12. Molecule sublimation as a tracer of protostellar accretion: Evidence for accretion bursts from high angular resolution C18O images

    CERN Document Server

    Jorgensen, Jes K; Williams, Jonathan P; Bergin, Edwin A

    2015-01-01

    The accretion histories of embedded protostars are an integral part of descriptions of their physical and chemical evolution. In particular, are the accretion rates smoothly declining from the earlier toward later stages or in fact characterized by variations such as intermittent bursts? We aim to characterize the impact of possible accretion variations in a sample of embedded protostars by measuring the size of the inner regions of their envelopes where CO is sublimated and relate those to their temperature profiles dictated by their current luminosities. Using observations from the Submillimeter Array we measure the extents of the emission from the C18O isotopologue toward 16 deeply embedded protostars. We compare these measurements to the predicted extent of the emission given the current luminosities of the sources through dust and line radiative transfer calculations. Eight out of sixteen sources show more extended C18O emission than predicted by the models. The modeling shows that the likely culprit for...

  13. 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.

  14. Oxygen isotopes in tree rings record variation in precipitation δ(18)O and amount effects in the south of Mexico.

    Science.gov (United States)

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

    2013-12-01

    [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 (δ(18)Otr). Interannual variation in δ(18)Otr was highly synchronized between trees and closely related to isotopic composition of rain measured at San Salvador, 710 km to the southwest. Correlations with δ(13)C, growth, or local climate variables (temperature, cloud cover, vapor pressure deficit (VPD)) were relatively low, indicating weak plant physiological influences. Interannual variation in δ(18)Otr 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 (18)O-depleted rain in the region and seem to have affected the δ(18)Otr 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 δ(18)Otr of M. acantholoba can be used as a proxy for source water δ(18)O and that interannual variation in δ(18)Oprec is caused by a regional amount effect. This contrasts with δ(18)O 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

  15. 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

    2013-12-01

    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

  16. Particle emission in the light heavy-ion fusion reactions: 14N, 16,18O+ 12C

    Science.gov (United States)

    Carlin Filho, N.; Coimbra, M. M.; Acquadro, J. C.; Liguori Neto, R.; Szanto, E. M.; Farrelly-Pessoa, E.; Szanto de Toledo, A.

    1985-01-01

    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 fusion may be obtained. The 14N, 16,18O+ 12C reactions were investigated in the energy range 30 MeVJcr), offering an alternative method for the total fusion cross-section determination.

  17. 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.

  18. 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.

  19. Stable isotope variations (δ18O and δD) in modern waters across the Andean Plateau

    Science.gov (United States)

    Bershaw, John; Saylor, Joel E.; Garzione, Carmala N.; Leier, Andrew; Sundell, Kurt E.

    2016-12-01

    Environmental parameters that influence the isotopic composition of meteoric water (δ18O and δD) are well characterized up the windward side of mountains, where orographic precipitation results in a predictable relationship between the isotopic composition of precipitation and elevation. The topographic and climatic evolution of the Andean Plateau and surrounding regions has been studied extensively by exploiting this relationship through the use of paleowater proxies. However, interpretation on the plateau itself is challenged by a poor understanding of processes that fractionate isotopes during vapor transport and rainout, and by the relative contribution of unique moisture sources. Here, we present an extensive dataset of modern surface water samples for the northern Andean Plateau and surrounding regions to elucidate patterns and causes of isotope fractionation in this continental environment. These data show a progressive increase in δ18O of stream water west of the Eastern Cordillera (∼1‰/70 km), almost identical to the rate observed across the Tibetan Plateau, attributed to a larger fraction of recycled water in precipitation and/or increased evaporative enrichment downwind. This may lead to underestimates of paleoelevation, particularly for sites deep into the rainshadow of the Eastern Cordilleran crest. That said, elevation is a primary control on the isotopic composition of surface waters across the entire Andean Plateau and its flanks when considering the most negative δ18O values, highlighting the need for sufficiently large datasets to distinguish minimally evaporated samples. There is a general increase in δ18O on the plateau from north to south, concomitant with an increase in aridity and decrease in convective moistening (amount effect). Lastly, stable isotope and seasonal precipitation patterns suggest easterlies provide the vast majority of moisture that falls as precipitation across the Andean Plateau and Western Cordillera, from Peru to

  20. 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

  1. Physical properties of the OMC-2 and OMC-3 cores from CS and C(18)O observations

    Science.gov (United States)

    Castets, A.; Langer, W. D.

    1995-01-01

    We have investigated the properties of the OMC-2 and OMC-3 cores in the Orion giant molecular cloud using high spatial spectral resolution observations of several transitions of the (13)CO, C(18)O, C(S-32) and C(S-34) molecules taken with the SEST telescope. The OMC-2 core consists of one clump (22 solar mass) with a radius of 0.11 pc surrounded by a cluster of 11 discrete infrared sources. The H2 column density and volume density in the center of this clump are 2 x 10(exp 22)/sq cm and 9 x 10(exp 5)/cu cm respectively. From a comparison between physical parameters derived from C(18)O and C(S-32) observations we conclude that the molecular envelope around the core has been completely removed by these sources and that only the very dense gas is left. OMC-3 shows a more complex elongated structure in C(18)O and CS than OMC-2. The C(S-32) and C(S-34) maps show that the denser region can be separated into at least sub-cores of roughly equal sizes (radius approximately equals 0.13 pc), with n(H2) = 6 x 10(exp 5)/cu cm, and a mass of 10 solar mass (from C(S-32)). The very different masses obtained for the central core from C(18)O and C(S-32) (55 and 12 solar mass respectively) indicate that a massive envelope is still present around the very dense sub-cores. We report the first detection of several molecular outflows in OMC-3. The presence of an IRAS source and the first detection of these outflows confirm that star formation is going on in OMC-3. Based on the different physical properties of these regions compared with OMC-1, OMC-2 appears to be in an intermediate evolutionary stage between OMC-1 and OMC-3.

  2. 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.

  3. 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.

  4. Multi-century humidity reconstructions from the southeastern Tibetan Plateau inferred from tree-ring δ18O

    Science.gov (United States)

    Wernicke, Jakob; Hochreuther, Philipp; Grießinger, Jussi; Zhu, Haifeng; Wang, Lily; Bräuning, Achim

    2017-02-01

    We present two new multi-century long tree-ring δ18O chronologies from the southeastern Tibetan Plateau. The longer chronology dates back to 1353 CE, representing the longest annually resolved δ18O chronology in the region, covering 660 years (1353-2012 CE). Both chronologies show strong relations to summer season precipitation, relative humidity, and temperature. We applied linear transfer functions and developed a summer season precipitation and a summer season relative humidity reconstruction. Moisture conditions during the past six centuries were characterized by a more humid period during 1700-1850 CE and a drying trend since the mid-19th century. Spatial correlations between the δ18O chronologies and gridded reanalysis data (ERA-20C) revealed strong regional and remote associations to west central Asian, northeastern Europe, and to the western equatorial Pacific. These findings imply a potential influence of (i) atmospheric wave trains emanating from the North Atlantic and (ii) equatorial Pacific sea surface temperatures on the moisture variability over southeastern Tibet.

  5. 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.

  6. 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.

  7. 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%).

  8. 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

  9. 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

  10. 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

  11. Air mass origin signals in δ 18O of tree-ring cellulose revealed by back-trajectory modeling at the monsoonal Tibetan plateau

    Science.gov (United States)

    Wernicke, Jakob; Hochreuther, Philipp; Grießinger, Jussi; Zhu, Haifeng; Wang, Lily; Bräuning, Achim

    2016-12-01

    A profound consideration of stable oxygen isotope source water origins is a precondition for an unambiguous palaeoenvironmental interpretation of terrestrial δ 18O archives. To stress the influence of air mass origins on widely used δ 18O tree-ring chronologies, we conducted correlation analyses between six annually resolved δ 18O tree-ring cellulose ( δ ^{18}O_{TC}) chronologies and mean annual air package origins obtained from backward trajectory modeling. This novel approach has been tested for a transect at the southeastern Tibetan plateau (TP), where air masses with different isotopic composition overlap. Detailed examinations of daily precipitation amounts and monthly precipitation δ 18O values ( δ ^{18}OP) were conducted with the ERA Interim and Laboratoire de Météorologie Dynamique General Circulation Model (LMDZiso) data, respectively. Particularly the southernmost study sites are influenced by a distinct amount effect. Here, air package origin δ ^{18}O_{TC} relations are generally weaker in contrast to our northern located study sites. We found that tree-ring isotope signatures at dry sites with less rain days per year tend to be influenced stronger by air mass origin than tree-ring isotope values at semi-humid sites. That implies that the local hydroclimate history inferred from δ ^{18}O_{TC} archives is better recorded at semi-humid sites.

  12. Similarity between the C18O (J=1-0) core mass function and the IMF in the S 140 region

    CERN Document Server

    Ikeda, Norio

    2011-01-01

    We present the results of C18O(J=1-0) mapping observations of a 20'x18' area in the Lynds 1204 molecular cloud associated with the Sharpless 2-140 (S140) H II region. The C18O cube (alpha-delta-vLSR) data shows that there are three clumps with sizes of \\sim 1 pc in the region. Two of them have peculiar red shifted velocity components at their edges, which can be interpreted as the results of the interaction between the cloud and the Cepheus Bubble. From the C18O cube data, the clumpfind identified 123 C18O cores, which have mean radius, velocity width in FWHM, and LTE mass of 0.36\\pm0.07 pc, 0.37\\pm0.09 km s-1, and 41\\pm29 Msun, respectively. All the cores in S140 are most likely to be gravitationally bound by considering the uncertainty in the C18O abundance. We derived a C18O core mass function (CMF), which shows a power-law-like behavior above a turnover at 30 Msun. The best-fit power-law index of -2.1\\pm0.2 is quite consistent with those of the IMF and the C18O CMF in the OMC-1 region by Ikeda & Kitam...

  13. Wood {delta}13C, {delta}18O and radial growth responses of residual red pine to variable retention harvesting.

    Science.gov (United States)

    Powers, Matthew D; Pregitzer, Kurt S; Palik, Brian J; Webster, Christopher R

    2010-03-01

    Variable retention harvests are used to enhance the development of structural complexity in managed forests by retaining living trees and other structural legacies from the pre-harvest ecosystem. While harvesting should increase resource availability to residual trees, greater crown exposure may also increase environmental stress, which makes it difficult to predict growth in different structural environments. We used stable carbon isotope ratios (delta(13)C) of annual rings from red pine trees (Pinus resinosa Ait.) as an index of intrinsic water use efficiency (iWUE), the ratio of photosynthetic carbon assimilation (A) to stomatal conductance (g(s)), to better understand how differences in physiological performance relate to growth responses following harvests that left residuals dispersed, aggregated between small (0.1 ha) gaps or aggregated between large (0.3 ha) gaps. Stable oxygen isotope ratios (delta(18)O) were used as an index of g(s) to investigate the drivers behind changes in iWUE. Retention harvesting did not appear to affect delta(13)C or delta(18)O at the stand scale when compared to unharvested control stands, but there was a significant, negative correlation between residual tree delta(13)C and plot basal area in the second and third years after harvesting that suggests declining iWUE as overstory competition increases. Residual tree delta(18)O was similar across treatments and basal areas. Trees in variable retention harvests showed small but positive increases in radial growth from the pre-treatment to post-treatment measurement periods, while radial growth declined in unharvested control stands. There were no significant differences in radial growth among retention treatments. Our results suggest residual red pine in relatively open environments benefit from greater A but do not show evidence of changes in g(s) that would indicate altered water relations.

  14. 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

  15. Decade-Scale Trend in Sea Water Salinity Revealed through d18O Analysis of Montastraea Annularis Annual Growth Bands

    Science.gov (United States)

    Halley, Robert B.; Swart, Peter K.; Dodge, Richard E.; Hudson, J. Harold

    1994-01-01

    Stable oxygen isotope ratios (18O) of coral skeletons are influenced by ambient water temperature and by the oxygen isotope ratio in the surrounding sea water, which, in turn, is linked to evaporation (salinity) and precipitation. To investigate this relationship more thoroughly, we collected hourly temperature data from the Hen and Chickens Reef in the Florida Keys between 1975 and 1988 and compared them to the 18O of Montastraea annularis skeleton that grew during the same interval. To ensure that we obtained the correct oxygen isotopic range in the skeleton we typically sampled the coral at a resolution of 20-30 samples in 1 year; in 1 year we sampled the coral at a resolution of 70 samples x year-1. Despite our high-resolution sampling, we were unable to obtain the full temperature-induced 18O range in the skeleton. Our data suggest that, during the summer, evaporation causes isotopic enrichment in the water, partially masking the temperature-induced signal. Our data also show that oxygen isotopic composition of seawater at the reef has increased since 1981. This increase indicates that salinity has increased slightly during the past decade, perhaps as a result of increased evaporation in waters of Florida Bay and the Keys. This phenomenon is probably not caused by a decrease in the outflow of freshwater into Florida Bay from the Everglades but may be related to the measured deficit in precipitation that has occurred over the past decade.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 12CO, 13CO and C18O observations along the major axes of nearby bright infrared galaxies

    Institute of Scientific and Technical Information of China (English)

    Qing-Hua Tan; Yu Gao; Zhi-Yu Zhang; Xiao-Yang Xia

    2011-01-01

    We present simultaneous observations of 12CO, 13CO and C18O J=1-0 emission in 11 nearby (cz < 1000km s-1) bright infrared galaxies. Both 12CO and 13CO are detected in the centers of all the galaxies, except for 13CO in NGC 3031.We have also detected C18O, CSJ=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 14 m telescope. We have conducted half-beam-spaced 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 the 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 our or literature data) show little variation with galactocentric radius, in sharp contrast with the greatly varied R. This supports the notion that the observed gradient in R could be the result of the variations of the physical conditions across the disks. The H2 column density derived from C18O shows that the Galactic standard conversion factor (X-factor) overestimates the amount of the molecular gas in M82 by a factor of ~2.5. These observations suggest that the X-factor in active star-forming regions (i.e., nuclear regions) should be lower than that in normal star-forming disks and the gradient in R can be used to trace the variations of the X-factor.

  1. 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.

    The interrelationship between mean proloculus size (MPS), delta super(18) O and delta super(13) C vatiations in benthic foraminiferal species Rotalidium annectens and their relation with temperature (T) and salinity (S) have been studied in samples...

  2. 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.

  3. 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.

  4. CHIMPS: the $^{13}$CO/C$^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane Survey

    CERN Document Server

    Rigby, A J; Plume, R; Eden, D J; Urquhart, J S; Thompson, M A; Mottram, J C; Brunt, C M; Butner, H M; Dempsey, J T; Gibson, S J; Hatchell, J; Jenness, T; Kuno, N; Longmore, S N; Morgan, L K; Polychroni, D; Thomas, H; White, G J; Zhu, M

    2015-01-01

    We present the $^{13}$CO/C$^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) which has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope (JCMT) in Hawaii. The high-resolution spectral survey currently covers |b| < 0.5 deg and 28 < l < 46 deg, with an angular resolution of 15 arcsec in 0.5 km/s velocity channels. The spectra have a median rms of $\\sim$ 0.6 K at this resolution, and for optically thin gas at an excitation temperature of 10 K, this sensitivity corresponds to column densities of $N_{\\mathrm{H}_{2}} \\sim 3 \\times 10^{20}\\,$cm$^{-2}$ and $N_{\\mathrm{H}_{2}} \\sim 4 \\times 10^{21}\\,$cm$^{-2}$ for $^{13}$CO and C$^{18}$O, respectively. The molecular gas that CHIMPS traces is at higher column densities and is also more optically thin than in other publicly available CO surveys due to its rarer isotopologues, and thus more representative of the three-dimensional structure of the clouds. The critical density of the J=3-2 transit...

  5. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-05-03

    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 environmental electron receptors. LC/MS/MS analysis resulted in the identification of about 79% membrane proteins among all proteins identified from the enriched sample. To illustrate the quantification of membrane proteome changes, enriched membrane protein samples from wild-type and mutant cells (generated from deletion of a type II secretion protein, GspD) were further labeled with 16O and 18O at the peptide level prior to LC-MS analysis. A chemical-probe-labeled pure protein has also been used as an internal standard for normalization purpose. The quantitative data revealed reduced abundances of many outer membrane proteins such as OmcA and MtrC in ΔgspD mutant cells, which agreed well with previously published studies.

  7. 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

  8. 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; Pasa-Tolić, Ljiljana; Smith, Richard D; Lipton, Mary S

    2010-05-07

    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 (18)O 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 (16)O and (18)O 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 Delta gspD mutant cells of many outer membrane proteins including the outer membrane c-type cytochromes OmcA and MtrC, in agreement with a previous report that these proteins are substrates of the type II secretion system.

  9. Synergy of W18O49 and polyaniline for smart supercapacitor electrode integrated with energy level indicating functionality.

    Science.gov (United States)

    Tian, Yuyu; Cong, Shan; Su, Wenming; Chen, Hongyuan; Li, Qingwen; Geng, Fengxia; Zhao, Zhigang

    2014-01-01

    Supercapacitors are important energy storage technologies in fields such as fuel-efficient transport and renewable energy. State-of-the-art supercapacitors are capable of supplanting conventional batteries in real applications, and supercapacitors with novel features and functionalities have been sought for years. Herein, we report the realization of a new concept, a smart supercapacitor, which functions as a normal supercapacitor in energy storage and also communicates the level of stored energy through multiple-stage pattern indications integrated into the device. The metal-oxide W18O49 and polyaniline constitute the pattern and background, respectively. Both materials possess excellent electrochemical and electrochromic behaviors and operate in different potential windows, -0.5-0 V (W18O49) and 0-0.8 V (polyaniline). The intricate cooperation of the two materials enables the supercapacitor to work in a widened, 1.3 V window while displaying variations in color schemes depending on the level of energy storage. We believe that our success in integrating this new functionality into a supercapacitor may open the door to significant opportunities in the development of future supercapacitors with imaginative and humanization features.

  10. 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...

  11. 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...

  12. Scale dependence of environmental and physiological correlates of δ18O and δ13C in the magnesium calcite skeletons of bamboo corals (Gorgonacea; Isididae)

    Science.gov (United States)

    Thresher, Ronald E.; Neil, Helen

    2016-08-01

    We examine in detail δ18O and δ13C in the calcite internodes of bamboo corals as potential proxies of physiological and environmental variability, through (a) a "core top" calibration that includes specimens from a wide range of habitats and environmental conditions and (b) a comparison of high resolution serial point analyses along radial growth axes of a sub-set of specimens with each other, with instrumental temperature and salinity records, with growth rates and with a nominal skeletal proxy for temperature (Mg/Ca) in the same specimens. At the whole-of-specimen level, δ18O and the intercept of the strong within-specimen regression of δ18O against δ13C correlates highly with ambient temperatures at slopes that are identical to those reported for other marine biogenic carbonates (-0.22 per °C). δ13C varies predominantly with apparent specimen-mean growth rate. It also correlates with the slope of the within-specimen covariance between δ18O and δ13C, which in turn is distributed bi-modally among specimens and linked to differences in apparent growth rates. Within-specimens, variability in δ13C, and to a lesser extent δ18O, correlates between specimens collected in the same region and differs between regions, implying an environmental effect, but the factors involved for either isotope ratio are unclear. Correlations between δ18O and temperature (and Mg/Ca) range from positive to negative among specimens and appear to vary over time even within specimens. The mismatch between the consistent temperature-dependence of δ18O at the whole-of-specimen level and the mixed relationship within-specimens can be reconciled by assuming an unknown temperature-dependent factor affecting δ18O during the growth of Isidid calcite. The contrast between the results of the "core top" temperature calibration for δ18O, which are consistent with studies of other carbonates, and the apparently more complex suite of factors affecting both δ13C and δ18O within specimens

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Within-canopy and ozone fumigation effects on delta13C and Delta18O in adult beech (Fagus sylvatica) trees: relation to meteorological and gas exchange parameters.

    Science.gov (United States)

    Gessler, Arthur; Löw, Markus; Heerdt, Christian; de Beeck, Maarten Op; Schumacher, Johannes; Grams, Thorsten E E; Bahnweg, Günther; Ceulemans, Reinhart; Werner, Herbert; Matyssek, Rainer; Rennenberg, Heinz; Haberer, Kristine

    2009-11-01

    In this study, the effects of different light intensities either in direct sunlight or in the shade crown of adult beech (Fagus sylvatica L.) trees on delta13C and Delta18O were determined under ambient (1 x O3) and twice-ambient (2 x O3) atmospheric ozone concentrations during two consecutive years (2003 and 2004). We analysed the isotopic composition in leaf bulk, leaf cellulose, phloem and xylem material and related the results to (a) meteorological data (air temperature, T and relative humidity, RH), (b) leaf gas exchange measurements (stomatal conductance, g(s); transpiration rate, E; and maximum photosynthetic activity, A(max)) and (c) the outcome of a steady-state evaporative enrichment model. Delta13C was significantly lower in the shade than in the sun crown in all plant materials, whilst Delta18O was increased significantly in the shade than in the sun crown in bulk material and cellulose. Elevated ozone had no effect on delta13C, although Delta18O was influenced by ozone to varied degrees during single months. We observed significant seasonal changes for both parameters, especially in 2004, and also significant differences between the study years. Relating the findings to meteorological data and gas exchange parameters, we conclude that the differences in Delta18O between the sun and the shade crown were predominantly caused by the Péclet effect. This assumption was supported by the modelled Delta18O values for leaf cellulose. It was demonstrated that independent of RH, light-dependent reduction of stomatal conductance (and thus transpiration) and of A(max) can drive the pattern of Delta18O increase with the concomitant decrease of delta13C in the shade crown. The effect of doubling ozone levels on time-integrated stomatal conductance and transpiration as indicated by the combined analysis of Delta18O and delta13C was much lower than the influence caused by the light exposure.

  19. 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

  20. 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.

  1. Seawater intrusion into groundwater aquifer through a coastal lake - complex interaction characterised by water isotopes (2)H and (18)O.

    Science.gov (United States)

    Gemitzi, Alexandra; Stefanopoulos, Kyriakos; Schmidt, Marie; Richnow, Hans H

    2014-01-01

    The present study investigates the complex interactions among surface waters, groundwaters and a coastal lake in northeastern Greece, using their stable isotopic composition (δ(18)O, δ(2)H) in combination with hydrogeological and hydrochemical data. Seasonal and spatial trends of water isotopes were studied and revealed that all water bodies in the study area interact. It was also shown that the aquifer's increased salinity is not due to fossil water from past geological periods, but is attributed to brackish lake water intrusion into the aquifer induced by the extensive groundwater pumping for irrigation purposes. Quantification of the contribution of the lake to the aquifer was achieved using the simple dilution formula. The isotopic signatures of the seawater and the groundwaters are considerably different, so there is a very little possibility of direct seawater intrusion into the aquifer.

  2. Oxygen isotope evolution of the Lake Owyhee volcanic field, Oregon, and implications for low-δ18O magmas of the Snake River Plain - Yellowstone hotspot

    Science.gov (United States)

    Blum, T.; Kitajima, K.; Nakashima, D.; Valley, J. W.

    2013-12-01

    The Snake River Plain - Yellowstone (SRP-Y) hotspot trend is one of the largest known low-δ18O magmatic provinces, yet the timing and distribution of hydrothermal alteration relative to hotspot magmatism remains incompletely understood. Existing models for SRP-Y low-δ18O magma genesis differ regarding the timing of protolith alteration (e.g. Eocene vs. present), depth at which alteration occurs (e.g. 15 km vs. Owyhee volcanic field (LOVF) of east central Oregon to further identify magmatic oxygen isotope trends within the field. These data offer insight into the timing of alteration and the extent of the greater SRP-Y low-δ18O province, as well as the conditions that generate large low-δ18O provinces. 16-14 Ma silicic volcanism in the LOVF is linked to the pre-14 Ma SRP-Y hotspot, with volcanism partially overlapping extension in the north-south trending Oregon-Idaho Graben (OIG). Ion microprobe analyses of zircons from 16 LOVF silicic lavas and tuffs reveal homogeneous zircons on both the single grain and hand sample scales: individual samples have 2 S.D. for δ18O ranging from 0.27 to 0.96‰ (SMOW), and sample averages ranging from 1.8 to 6.0‰, excluding texturally chaotic and/or porous zircons which have δ18O values as low as 0.0‰. All low-δ18O LOVF magmas, including the caldera-forming Tuff of Leslie Gulch and Tuff of Spring Creek, are confined to the OIG, although not all zircons from within the OIG have low δ18O values. The presence and sequence of low-δ18O magmas in the LOVF and adjacent central Snake River Plain (CSRP) cannot be explained by existing caldera subsidence or pre-hotspot source models. These data, however, combined with volumetrically limited low-δ18O material in the adjacent Idaho Batholith and Basin and Range, are consistent with low-δ18O magmas generated by the superposition of high hotspot-derived thermal fluxes on active extensional structures (OIG extension in the LOVF, and Basin and Range rifting in the CSRP) thereby

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. Discovery of competing anaerobic and aerobic pathways in umpolung amide synthesis allows for site-selective amide 18O-labeling.

    Science.gov (United States)

    Shackleford, Jessica P; Shen, Bo; Johnston, Jeffrey N

    2012-01-03

    The mechanism of umpolung amide synthesis was probed by interrogating potential sources for the oxygen of the product amide carbonyl that emanates from the α-bromo nitroalkane substrate. Using a series of (18)O-labeled substrates and reagents, evidence is gathered to advance two pathways from the putative tetrahedral intermediate. Under anaerobic conditions, a nitro-nitrite isomerization delivers the amide oxygen from nitro oxygen. The same homolytic nitro-carbon fragmentation can be diverted by capture of the carbon radical intermediate with oxygen gas (O(2)) to deliver the amide oxygen from O(2). This understanding was used to develop a straightforward protocol for the preparation of (18)O-labeled amides in peptides by simply performing the umpolung amide synthesis reaction under an atmosphere of 18O2.

  9. 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.

  10. 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 leaf

  11. Sr/Ca and {delta} {sup 18}O ratios measured from Acropora nobilis and Porites lutea: Is Sr/Ca paleo-thermometry always reliable?; Mesures conjointes des rapports Sr/Ca et {delta} {sup 18}O effectuees sur Acropora nobilis et Porites lutea: le paleothermometre Sr/Ca est-il toujours fiable?

    Energy Technology Data Exchange (ETDEWEB)

    Boiseau, M.; Trupin, L.; Juillet-Leclerc, A. [Centre National de la Recherche Scientifique (CNRS), 91 - Gif-sur-Yvette (France). Centre des Faibles Radioactivites; Cornu, H. [Centre National de la Recherche Scientifique (CNRS), Lab. d' oceanographie dynamique et de climatologie, Unite mixte CNRS-ORSTOM-UPCM, 75 - Paris (France)

    1997-11-01

    We measured the Sr/Ca and {sup 18}O/{sup 16}O ratios in Acropora nobilis and Porites lutea, from the Mayotte lagoon. As the variations of {delta}{sup 18}O{sub seawater} are negligible, coral {delta}{sup 18}O{sub aragonite} reflects only seasonal temperature variations. While there is a good agreement between the Sr/Ca ratio and {delta}{sup 18}O 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{sup 2+} and Ca{sup 2+} and the presence of two mineralogical structures of strontium may affect the Sr/Ca ratio.

  12. 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

  13. 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...

  14. Disequilibrium δ18O values in microbial carbonates as a tracer of metabolic production of dissolved inorganic carbon

    Science.gov (United States)

    Thaler, Caroline; Millo, Christian; Ader, Magali; Chaduteau, Carine; Guyot, François; Ménez, Bénédicte

    2017-02-01

    Carbon and oxygen stable isotope compositions of carbonates are widely used to retrieve paleoenvironmental information. However, bias may exist in such reconstructions as carbonate precipitation is often associated with biological activity. Several skeleton-forming eukaryotes have been shown to precipitate carbonates with significant offsets from isotopic equilibrium with water. Although poorly understood, the origin of these biologically-induced isotopic shifts in biogenic carbonates, commonly referred to as "vital effects", could be related to metabolic effects that may not be restricted to mineralizing eukaryotes. The aim of our study was to determine whether microbially-mediated carbonate precipitation can also produce offsets from equilibrium for oxygen isotopes. We present here δ18O values of calcium carbonates formed by the activity of Sporosarcina pasteurii, a carbonatogenic bacterium whose ureolytic activity produces ammonia (thus increasing pH) and dissolved inorganic carbon (DIC) that precipitates as solid carbonates in the presence of Ca2+. We show that the 1000 lnαCaCO3-H2O values for these bacterially-precipitated carbonates are up to 24.7‰ smaller than those expected for precipitation at isotopic equilibrium. A similar experiment run in the presence of carbonic anhydrase (an enzyme able to accelerate oxygen isotope equilibration between DIC and water) resulted in δ18O values of microbial carbonates in line with values expected at isotopic equilibrium with water. These results demonstrate for the first time that bacteria can induce calcium carbonate precipitation in strong oxygen isotope disequilibrium with water, similarly to what is observed for eukaryotes. This disequilibrium effect can be unambiguously ascribed to oxygen isotope disequilibrium between DIC and water inherited from the oxygen isotope composition of the ureolytically produced CO2, probably combined with a kinetic isotope effect during CO2 hydration/hydroxylation. The fact that

  15. 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

  16. 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

  17. Tooth Enamel δ13C and δ18O Variations in Modern and Archaeological Horses From Northern Kazakhstan as Indicators of Regional Climate

    Science.gov (United States)

    Sikora, M. T.; Rosenmeier, M. F.; Stacy, E. M.; Olsen, S. L.

    2007-12-01

    In this study, the oxygen and carbon isotope values of tooth enamel were measured in forty-one modern and twenty-three Copper Age (3600 - 3100 B.C.) horse specimens from the grassland steppe region of northern Kazakhstan. Modern tooth enamel δ13C and δ18O values were compared with the carbon isotopic compositions of local vegetation and the δ18O values of meteoric waters. Tooth enamel isotope values within the Copper Age specimens (attributed to the so-called Botai culture) were, in turn, compared with modern samples. Average carbon isotopic values within modern bulk tooth enamel samples ranged between -13.7 and -12.0‰ (VPDB). This suggests that the diet of modern northern Kazakhstani horses is comprised almost entirely of C3 plants (considering enamel-diet fractionation factors) consistent with documented grassland compositions within the region. The observed amplitude of δ13C variations within individual teeth (typically less than ~2‰) suggests only minimal seasonal variation in the δ13C of grasses attributed to heat and water stress. Alternatively, the minimal seasonal changes observed within intra-tooth δ13C values may be the direct result of fodder provisioning. Ingested water δ18O values derived from oxygen isotope ratios within bulk tooth enamel samples appear statistically indistinguishable from estimates of regional precipitation, suggesting that Kazakhstani horse tooth enamel δ18O measurements may be used as a direct estimate of the oxygen isotopic composition of meteoric waters. Intra-tooth oxygen isotopic variations therefore reflect the pronounced seasonal variability in precipitation δ18O values tied to temperature changes and amount effects observed annually within Kazakhstan. However, these intra-tooth isotopic variations exhibit slightly reduced amplitudes relative to meteoric water values, suggesting that horses likely consume water from buffered sources such as lakes and wells. Average bulk tooth enamel δ13C values within

  18. 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.

  19. 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.

  20. 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.

  1. Oceanography in northwestern Europe during the last interglacial from intrashell δ 18O ranges in Littorina littorea gastropods

    Science.gov (United States)

    Burman, Johan; Påsse, Tore

    2008-07-01

    Coastal sea-surface temperature (SST) and sea-surface salinity (SSS), including seasonality, in northwest (NW) Europe during the early phase of the Eemian interglacial ca. 125 ka ago were reconstructed from Littorina littorea (common periwinkle) gastropods. The results were based on intra-annual δ 18O analyses in recent and fossil shells, mainly originating from the sea of Kattegat (Sweden) and the English Channel (United Kingdom), and confined to intertidal settings. The Eemian L. littorea shells indicated annual SSTs in the range 8-18°C for the English Channel and 8-26°C for Kattegat. All specimens from the Eemian sites experienced summer SSTs of ca. 1-3°C above recent conditions. The estimated winter SST in the English Channel during the Eemian was comparable to modern measurements of ca. 8°C. However, the Kattegat region displayed Eemian winter SST approximately 8°C warmer than today, and similar to conditions in the western English Channel. The recent-fossil isotope analogue approach indicated high SSS above 35 practical salinity units (psu) for a channel south of England in full contact with the North Atlantic Ocean during the last interglacial. In addition, the Kattegat shells indicated a SSS of ca. 29 psu, which points out a North Sea affinity for this region during the Eemian.

  2. 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...

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

    Directory of Open Access Journals (Sweden)

    R. Léguillon

    2016-10-01

    Full Text Available 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.

  4. 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.

  5. 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.

  6. 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

  7. 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...

  8. Drought history inferred from tree ring δ 13C and δ 18O in the central Tianshan Mountains of China and linkage with the North Atlantic Oscillation

    Science.gov (United States)

    Xu, Guobao; Liu, Xiaohong; Qin, Dahe; Chen, Tuo; Sun, Weizhen; An, Wenling; Wang, Wenzhi; Wu, Guoju; Zeng, Xiaomin; Ren, Jiawen

    2014-05-01

    Annual tree ring δ 18O and δ 13C chronologies from 1790 to 2008 were established using Tianshan spruce ( Picea schrenkiana) in the central Tianshan Mountains of northwestern China. Temperature has a positive effect on tree ring δ 18O and δ 13C in the study area, while precipitation and relative humidity have negative effects. The standardized precipitation-evapotranspiration index (SPEI) considered all of these effects and was significantly negatively correlated with tree ring δ 18O and δ 13C. We combined the tree ring δ 18O and δ 13C series to reconstruct the past 192 years of SPEI, which accounted for about 46 % of the total variance of SPEI from 1950 to 2006. The reconstruction showed good spatial agreement with gridded data in Palmer Drought Severity Index and precipitation and an inverse relationship with temperature. Our SPEI reconstruction reveals several wet and dry periods over the past 192 years and has good agreement with other drought records. Wavelet analysis showed quasi-periodic 10-, 20-, 30-, and 70-year fluctuations in the reconstruction. The 10-, 20-, and 30-year periodicities may reflect the potential influence of North Atlantic Oscillation (NAO). Overall, this study indicates that the SPEI is a potential drought index, and the winter NAO affects regional moisture conditions in the long term.

  9. Spectroscopic strengths for /sup 6/Li-induced alpha-particle transfers on /sup 18/O at 72 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Tanabe, T.; Ogino, K.; Kadota, Y.; Haga, K.; Kitahara, T.; Shiba, T.

    1982-08-01

    The /sup 18/O(/sup 6/Li,d)/sup 22/Ne reaction has been studied at 72-MeV bombarding energy. The angular distributions for transitions to low-lying states in /sup 22/Ne are fitted by exact finite-range distorted-wave Born approximation calculations and yield relative spectroscopic factors in good agreement with theoretical predictions.

  10. 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

  11. 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.

  12. 13CO and C18O J=2-1 mapping of the environment of the Class 0 protostellar core SMM 3 in Orion B9

    CERN Document Server

    Miettinen, Oskari

    2012-01-01

    We attempt to achieve a better understanding of the gas distribution and velocity field around the deeply embedded Class 0 protostar SMM 3 in the Orion B9 star-forming region. Using the APEX 12-m telescope, we mapped the line emission from the J=2-1 rotational transition of two CO isotopologues, 13CO and C18O, over a 4' x 4' region around Orion B9/SMM 3. Both the 13CO and C18O lines exhibit two well separated velocity components at about 1.3 and 8.7 km/s. The emission of both CO isotopologues is more widely distributed than the submillimetre dust continuum emission as probed by LABOCA. The LABOCA 870-micron peak position of SMM 3 is devoid of strong CO isotopologue emission, which is consistent with our earlier detection of strong CO depletion in the source. No signatures of a large-scale outflow were found towards SMM 3. The 13CO and C18O emission seen at ~1.3 km/s is concentrated into a single clump-like feature at the eastern part of the map. The peak H2 column density towards a C18O maximum of the low-vel...

  13. 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.

  14. 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.

  15. Synthesis and Microwave Dielectric Properties of A16V18O61 (A = Ba, Sr and Ca) Ceramics for LTCC Applications

    Science.gov (United States)

    Suresh, E. K.; Prasad, K.; Arun, N. S.; Ratheesh, R.

    2016-06-01

    Low-temperature co-firable A16V18O61 (A = Ba, Sr, Ca) ceramics have been prepared through the solid state ceramic route. The structural features of these ceramics have been studied using the x-ray diffraction (XRD) technique. The existence of the A16V18O61 (A = Ba, Sr, Ca) ceramic phase was confirmed through laser Raman spectroscopic studies. Scanning electron microscopy analysis revealed a dense microstructure for the ceramics with closely packed polygonal grains. Among the samples studied, Ba16V18O61 ceramic was prepared in the ultralow sintering temperature of 620°C for 1 h, which can be co-firable with an aluminium electrode. XRD and electron dispersive spectroscopy analyses showed that the samples under study have excellent compatibility with metal electrodes. The microwave dielectric properties measured using a vector network analyzer revealed that A16V18O61 (A = Ba, Sr, Ca) ceramics have excellent unloaded quality factors.

  16. 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...

  17. 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

  18. A novel isotopic fractionation during dissolved oxygen consumption in mesopelagic waters inferred from observation and model simulation of dissolved oxygen δ18O in open oceanic regions

    Science.gov (United States)

    Nakayama, N.; Oka, A.; Gamo, T.

    2012-12-01

    Oxygen isotopic ratio (δ18O) of dissolved oxygen is a useful for bioactive tracer of the subsurface aphotic (mesopelagic) ocean since it varies nonlinearly related to oxygen consumption via stoichiometry of organic matter decomposition. Therefore, along with global circulation model (GCM), observed δ18O and their vertical/geographical distribution can be effectively used to quantitatively determine how marine biological and ocean physical processes contribute to varying dissolved oxygen (DO) concentration in the ocean, in particular mesopelagic zone where pronounced biological activity alters DO concentration significantly. In the central north Pacific Ocean and Indian Ocean, including Arabian Sea, one of the few regions in the open ocean which has oxygen minimum zone (OMZ, a layer with severely depleted DO), vertical profiles of DO and δ18O were observed. These observed data are compared with a GCM simulation in which a constant isotopic fractionation factor of DO by marine biological respiration and a fixed Redfield molar ratio between P and O are assumed. Even in the Arabian Sea OMZ, relationship between DO and δ18O was found to be similar to those observed in other open oceans, indicating that no specific oxygen consumption process occurred in the OMZ. Using the GCM model, we attempted to reproduce the observed overall relationship between DO and δ18O, but it failed when we adopted the previously reported isotopic fractionation factor: Discrepancy became larger when oxygen saturation level decreased, in particular in thermocline water (at 20% oxygen saturation level, modeled δ18O was heavier than observed values by +7‰). Sensitivity simulations with the GCM model revealed that (1) simply changing the intensity of oxygen consumption by respiration/organic matter decomposition nor physical processes (diffusion and/or advection) could explain the observed relationship between DO and δ18O, (2) applying a smaller isotopic fractionation for deep waters

  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)

    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.

  20. 南极雪的氢氧同位素组成%Deuterium and  18O Contents and Distributions in Antarctic Snow

    Institute of Scientific and Technical Information of China (English)

    刘广山; 黄奕普; 金德秋; 周锡煌

    2001-01-01

    The deuterium and  18O in various Antarctic snow samples including the surface snow, which collected along the track from Station Zhongshan to Dome A, overlying snow on sea-ice, fresh snow and lake water nearby Station Zhongshan, were measured. The results indicate that δD and δ18O in the surface snow of Antarctic inland were negatively correlated with the latitude and the sea-level elevation respectively. In the snow core from the overlying snow on sea-ice, the depth distributions of δD and δ18O appeared the feature of variation with the seasons. The relationship between δD and δ18O in various snow samples were studied. The relation equation for both δD and δ18O for fresh snow was most close to the Craig’s meteoric water line (MWL) and the equation for lake water far from MWL.%测定了南极中山站至Dome A沿线表层雪、中山站附近海冰上覆雪、新降雪和中山站附近湖水的D和18O,对内陆雪δD和δ18O随纬度和海拔高度的变化、海冰上覆雪δD和δ18O随深度的变化,各种雪中δD和δ18O之间的相关性进行了研究.

  1. 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.

  2. Floodplain ecohydrology: Discerning climatic v. anthropogenic controls from tree-ring δ18O, dendrochronology, and instrumental climate records

    Science.gov (United States)

    Singer, M. B.; Piégay, H.; Stella, J. C.; Wilson, R.

    2012-12-01

    Vegetation of lowland riparian zones in temperate climates is largely determined by floodplain water availability during the growth season. Floodplain water reservoirs are replenished seasonally by lateral hyporheic water from streamflow, which primarily contributes to phreatic zone water and by infiltration of precipitation, which typically controls seasonal vadose zone soil moisture. Water availability to species rooted to particular depths in the floodplain is subject to interannual variability in climate (e.g., precipitation magnitude, timing, and phase). Co-occurring tree species in the riparian zone may express differential adaptation to water availability and shifting water sources, especially if they are rooted at contrasting depths. We have developed an ecohydrologic approach to assess how climatic variability impacts water availability at different depths in the floodplain and corresponding tree growth in the Rhône River basin, France. We combine dendrochronology, tree ring isotopes (δ18O), and instrumental climate records to discern relationships between tree growth and water sources for two contrasting, co-occurring riparian species—the shallowly rooting Fraxinus excelsior and the obligate phreatophyte, Populus nigra (poplar). We developed growth time series via basal area increment (BAI) and extracted alpha-cellulose from tree rings to assess relative responses to water stress via δ18O contained in each annual ring, and we analyzed these data alongside streamflow, precipitation, and groundwater data. Our initial work on a tributary of the Rhône showed that F. excelsior generally indicates water availability in the vadose zone, while P. nigra provides a window into the phreatic zone. However, the rooting depths and water sources for these species overlap on particularly low topographic surfaces, where phreatic water is abundant for both. In contrast to prior assumptions, we found that P. nigra exhibits more growth sensitivity to drought stress

  3. 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.

  4. 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.

  5. Investigating human geographic origins using dual-isotope (87Sr/86Sr, δ18O) assignment approaches

    Science.gov (United States)

    Sonnemann, Till F.; Shafie, Termeh; Hofman, Corinne L.; Brandes, Ulrik; Davies, Gareth R.

    2017-01-01

    Substantial progress in the application of multiple isotope analyses has greatly improved the ability to identify nonlocal individuals amongst archaeological populations over the past decades. More recently the development of large scale models of spatial isotopic variation (isoscapes) has contributed to improved geographic assignments of human and animal origins. Persistent challenges remain, however, in the accurate identification of individual geographic origins from skeletal isotope data in studies of human (and animal) migration and provenance. In an attempt to develop and test more standardized and quantitative approaches to geographic assignment of individual origins using isotopic data two methods, combining 87Sr/86Sr and δ18O isoscapes, are examined for the Circum-Caribbean region: 1) an Interval approach using a defined range of fixed isotopic variation per location; and 2) a Likelihood assignment approach using univariate and bivariate probability density functions. These two methods are tested with enamel isotope data from a modern sample of known origin from Caracas, Venezuela and further explored with two archaeological samples of unknown origin recovered from Cuba and Trinidad. The results emphasize both the potential and limitation of the different approaches. Validation tests on the known origin sample exclude most areas of the Circum-Caribbean region and correctly highlight Caracas as a possible place of origin with both approaches. The positive validation results clearly demonstrate the overall efficacy of a dual-isotope approach to geoprovenance. The accuracy and precision of geographic assignments may be further improved by better understanding of the relationships between environmental and biological isotope variation; continued development and refinement of relevant isoscapes; and the eventual incorporation of a broader array of isotope proxy data. PMID:28222163

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

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sanjiv, E-mail: sanjucccm@rediffmail.com [National Centre for Compositional Characterization of Materials, BARC, ECIL Post, Hyderabad 500062 (India); Sunitha, Y.; Reddy, G.L.N.; Sukumar, A.A.; Ramana, J.V.; Sarkar, A. [National Centre for Compositional Characterization of Materials, BARC, ECIL Post, Hyderabad 500062 (India); Verma, Rakesh [Analytical Chemistry Division, BARC, Mumbai 400085 (India)

    2016-07-01

    The paper presents a proton induced γ-ray emission method based on {sup 18}O(p,αγ){sup 15}N 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 {sup 15}N 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 <8%. The reaction has a probing depth of several tens of microns. Interferences can arise from fluorine due to the occurrence of {sup 19}F(p,αγ){sup 16}O reaction that emits 6–7 MeV γ-rays. The analytical potential of the methodology is demonstrated by determining oxygen in several oxide as well as non-oxide materials.

  7. Neotropical eocene coastal floras and [sup 18]O/[sup 16]O-estimated warmer vs. cooler equatorial waters

    Energy Technology Data Exchange (ETDEWEB)

    Graham, A. (Kent State Univ., OH (United States))

    1994-03-01

    The history of the earth's sea-surface temperature (SST) in equatorial regions during the Tertiary is unsettled because of uncertainty as to the presence and extent of glaciers during the Paleogene. The [sup 16]O trapped in glaciers and subsequently released back to the ocean basins as meltwater during interglacials affects the [sup 18]O/[sup 16]O ratio of sea water, one of the variables that must be known for oxygen isotope paleotemperature analysis of calcareous fossils. Estimates of SST range from [approximately]18 to 20 C, assuming an ice-free earth, to [approximately]28 C assuming glaciers were present in the Paleogene. Low latitude SST presently averages 28C, so the former estimate gives a value 8 to 10 C cooler than present, while the latter gives a value as warm or slightly warmer than present. The figures are important for interpreting terrestrial vegetational history because the temperature differential between low and high latitudes is a major factor in determining global climates through the control of poleward transfer of heat. The middle( ) to late Eocene Gatuncillo Formation palynoflora of Panama was deposited at the ocean-continental interface at [approximately]9[degrees]N latitude. The individual components and paleocommunities are distinctly tropical and similar to the present vegetation along the Atlantic coast of southern Central America. This is consistent with data emerging from other recently studied tropical coastal biotas and represents a contribution from paleobiology toward eventually resolving the problem of Eocene equatorial marine environments. Collectively, the evidence is beginning to favor a model of Eocene SST near present values. 50 refs., 1 fig., 2 tabs.

  8. 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.

  9. 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.

  10. 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.

  11. High-Resolution ∂18O record of middle-late Holocene hydrologic variability from the central Peruvian Andes (Invited)

    Science.gov (United States)

    Rodbell, D. T.; Abbott, M.; Bird, B. W.; Stansell, N.

    2009-12-01

    Laguna Yuraicocha in the western cordillera of the central Peruvian Andes (12.53°S; 75.50°W; 4460 masl) is dammed by late glacial moraines and is underlain and surrounded by Jurassic and Cretaceous limestone interbedded with siliciclastic rocks. A 6.9 meter-long sediment core from the distal end of the lake is dominated by authigenic calcite (marl) with a mean concentration of 82 weight percent that has accumulated at a rate of ~ 1 mm yr-1 for the past 6200 years. The age model for the core is based on a combination of 210Pb and AMS 14C ages from charcoal; modern lake water is ~1‰ evaporatively enriched from mean regional precipitation. Marl samples were taken with an average sampling interval of 8 years; samples were treated to remove organic matter, sieved to concentrate the Andes. Subcentennial variance in 18O with an ~2‰ amplitude is persistent throughout the record. Time series analysis reveals strength in the 5-12 year window, which may record the influence of ENSO on the hydrologic balance of the region through its effect on the strength of the South American summer monsoon. Spectral strength is also present in the 40-200 year periodicity and this spectral component appears to weaken in the last millennium. The progressive increase in hydrologic balance during the middle-late Holocene is consistent with glacial geologic evidence for the onset of neoglaciation in the Peruvian Andes, including the dramatic reformation of the Quelccaya Ice Cap ~5100 years ago. This appears to confirm the notion that Andean glaciers, especially those in the southern and western cordillera of Peru and Bolivia, are especially sensitive to changes in regional moisture balance.

  12. Effects of Lu2O3 doping on the performance of Ba4Sm9.33Ti18O54 microwave dielectric ceramics%掺杂Lu2O3对Ba4Sm9.33Ti18O54微波介质陶瓷性能的影响

    Institute of Scientific and Technical Information of China (English)

    皮鑫鑫; 黄宝玉; 王丽熙; 张其土

    2012-01-01

    Doped Lu2O3Ba4Sm9.33Ti18O54 microwave dielectric ceramics were studied in order to improve dielectric performance of the ceramics. The solid solution formula was Ba4(Sin1-yLuy)9.33Ti18O54. The results show that the sintering temperature of BaSm9.33Ti18O54 microwave dielectric ceramics is reduced to 1 260 ℃ effectively by doping Lu2O3. When y=0.05, the major phase BaSm9.33Ti18O54 was similar to tungsten bronze type structure and the dielectric performance of Ba4(Sin1-yLuy)9.33Ti18O54microwave dielectric ceramics is more excellent: at 4.33 GHz, εr=76, Q ·f=2532, τf=-42×10-6 /℃. When y<0.5, there is BaSm2Ti4O12 phase; while y≧0.5, the main phase become pyrochlore phase and it does not behave dielectric properties.%以Ba4Sm9.33Ti18O54微波介质陶瓷为基础,掺杂Lu2O3进行改性,形成固溶式为Ba4(Sm1-yLuy)9.33Ti18O54的结构.结果表明,掺杂Lu2O3能很好地把Ba4Sm9.33Ti18O544微波介质陶瓷的烧结温度降至1 260℃,当y=0.05时Ba4Sm9.33Ti18O54为类钨青铜结构,能得到介电性能较佳的微波介质陶瓷:4.33 GHz时εr约为76,Q·f约为2 532,τf为-42×10-6/℃;y<0.5时生成了类钨青铜结构晶相,y≥0.5主晶相变成烧绿石相,不具备介电性.

  13. 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.

  14. 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

  15. 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.

  16. Organic-Inorganic Hybrid Materials Based on Basket-like {Ca⊂P6Mo18O73} Cages.

    Science.gov (United States)

    Zhang, He; Yu, Kai; Lv, Jing-hua; Gong, Li-hong; Wang, Chun-mei; Wang, Chun-xiao; Sun, Di; Zhou, Bai-Bin

    2015-07-20

    Four basket-like organic-inorganic hybrids, formulated as [{Cu(II)(H2O)2}{Ca4(H2O)4(HO0.5)3(en)2}{Ca⊂P6Mo4(V)Mo14(VI)O73}]·7H2O (1), (H4bth)[{Fe(II)(H2O)}{Ca⊂P6Mo18(VI)O73}]·4H2O (2), (H2bih)3[{Cu(II)(H2O)2}{Ca⊂P6Mo2(V)Mo16(VI)O73}]·2H2O (3), (H2bib)3[{Fe(II)(H2O)2}{Ca⊂P6Mo2(V) Mo16(VI)O73}]·4H2O (4), (bth = 1,6-bis(triazole)hexane; bih = 1,6-bis(imidazol)hexane; bib = 1,4-bis(imidazole)butane) have been hydrothermally synthesized and fully characterized. Compounds 1-4 contain polyoxoanion [Ca⊂P6Mon(V)Mo18-n(VI)O73]((6+n)-) (n = 0, 2, or 4) (abbreviated as {P6Mo18O73}) as a basic building block, which is composed of a "basket body" {P2Mo14} unit and a "handle"-liked {P4Mo4} fragment encasing an alkaline-earth metal Ca(2+) cation in the cage. Compound 1 exhibits an infrequent 2D layer structure linked by the Cu(H2O)2 linker and an uncommon tetranuclear calcium complex, while compound 2 is 8-connected 2-D layers connected by binuclear {Fe2(H2O)3} segaments, which are observed for the first time as 2-D basket-like assemblies. Compounds 3 and 4 are similar 1D Z-typed chains bonded by M(H2O)2 units (M = Cu for 3 and Fe for 4). The optical band gaps of 1-4 reveal their semiconductive natures. They exhibit universal highly efficient degradation ability for typical dyes such as methylene blue, methyl orange, and rhodamine B under UV light. The lifetime and catalysis mechanism of the catalysts have been investigated. The compounds also show good bifunctional electrocatalytic behavior for oxidation of amino acids and reduction of NO2(-).

  17. Stable isotope (δ18O and δ2H) data for precipitation, stream water, and groundwater in Puerto Rico

    Science.gov (United States)

    Scholl, Martha A.; Torres-Sanchez, Angel; Rosario-Torres, Manuel

    2014-01-01

    , hurricanes, and cold fronts, although frequent low-intensity orographic showers occur throughout the year in the mountains. The stable isotope signatures of rainfall (δ2H and δ18O) are broadly correlated with the weather type that produced the rainfall (Scholl and others, 2009; Scholl and Murphy, 2014).

  18. 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

  19. First application of the n - 9Be optical potential to the study of the 10Be continuum via the (18O,17O ) neutron-transfer reaction

    Science.gov (United States)

    Carbone, D.; Bondı, M.; Bonaccorso, A.; Agodi, C.; Cappuzzello, F.; Cavallaro, M.; Charity, R. J.; Cunsolo, A.; De Napoli, M.; Foti, A.

    2014-12-01

    The 9Be(18O,17O ) 10Be reaction has been studied at an incident energy of 84 MeV, and the ejectiles have been detected at forward angles. The 10Be excitation energy spectrum has been obtained up to about 18 MeV, and several known bound and resonant states of 10Be have been identified. Calculations that describe the interaction of the neutron removed from the 18O projectile with the 9Be target by means of an optical potential with a semiclassical approximation for the relative motion account for a significant part of the 10Be continuum. Two parametrizations of the optical-model potential for the system n - 9Be have been used and compared.

  20. 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.

  1. 纳米复合材料H6P2W18O62/TiO2(PS)紫外光催化降解甲基橙%UV photocatalytic activity of nano-composite H6P2W18O62/TiO2 (PS) for methyl orang

    Institute of Scientific and Technical Information of China (English)

    王丽华; 李莉; 王瑞卿; 张文治

    2013-01-01

    采用聚苯乙烯(PS)微球为模板剂,经溶胶-凝胶方法制备了复合材料H6P2W18O62/TiO2(PS)。经傅立叶-红外光谱(FT-IR)、紫外-可见漫反射(UV-Vis/DRS)以及扫描电子显微镜配合X-射线能量色散谱仪(SEM-EDS)等测试手段对上述合成材料的组成、结构及形貌进行了表征。结果显示,经PS微球处理后H6P2W18O62/TiO2(PS)中母体多酸的基本结构未发生明显变化,且该合成产物H6P2W18O62/TiO2(PS)呈单分散和密堆积圆球状结构。在紫外光催化降解甲基橙的实验研究中,纳米复合材料H6P2W18O62/TiO2(PS)表现出较好的光催化性能,其活性明显高于其它体系。%Nano-composite H6P2W18O62/TiO2(PS)was prepared by sol-gel method using polystyrene(PS) latex sphere as template. The phase compositions,structures and morphologies of H6P2W18O62/TiO2(PS)were well-characterized by FT-IR,UV-Vis/DRS and SEM-EDS. The results showed that the basic structure of polyoxometaltesin the nano-composite H6P2W18O62/TiO2(PS)has been basicly matained. Moreover,the composites which were used with PS had monodisperse and close packing of spherical structure. In addition,the results for photocatalytic degradation of methyl orang under UV light irradiaton show that the activity of nano-composite H6P2W18O62/TiO2 (PS)is better than that of other photocatalysts.

  2. 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.

  3. Variation of atmospheric CO, δ13C, and δ18O at high northern latitude during 2004-2009: Observations and model simulations

    Science.gov (United States)

    Park, Keyhong; Wang, Zhihui; Emmons, Louisa K.; Mak, John E.

    2015-10-01

    Atmospheric CO mixing ratios and stable isotope ratios (δ13C and δ18O) were measured at a high northern latitude site (Westman Islands, Iceland) from January 2004 to March 2010 in order to investigate recent multiyear trends of the sources of atmospheric carbon monoxide in the extratropical Northern Hemisphere. During this period, we observed a decrease of about 2% per year in CO mixing ratios with little significant interannual variability. The seasonal cycles for δ13C and δ18O in CO are similar to that in the CO mixing ratio, and there is a pronounced interannual variation in their seasonal extremes occurring in summer and fall, which is driven by changes in the relative contribution of different sources. Some of the sources of CO are anthropogenic in character (e.g., fossil fuel and biofuel combustion and agricultural waste burning), and some are primarily natural (e.g., oxidation atmospheric methane and other hydrocarbons and wildfires), and distinction among the various major sources can, more or less, be distinguished by the stable isotopic composition of CO. We compare our observations with simulations from a 3-D global chemical transport model (MOZART-4, Model for Ozone and Related Chemical Tracers, version 4). Our results indicate the observed trend of anthropogenic CO emissions is mostly responsible for the observed variation in δ13C and δ18O of CO during 2004-2009. Especially, the δ18O enriched sources such as fossil fuel and biofuel sources are controlling the variation. The modeling results indicate decreasing trends in the fossil fuel and biofuel source contributions at Iceland of -0.61 ± 0.26 ppbv/yr and -0.38 ± 0.10 ppbv/yr, respectively, during the observation period.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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. USGS46 Greenland ice core water – A new isotopic reference material for δ2H and δ18O measurements of water

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping; Tarbox, Lauren V.; Lorenz, Jennifer M.; Buck, Bryan

    2015-01-01

    Ice core from Greenland was melted, filtered, homogenised, loaded into glass ampoules, sealed, autoclaved to eliminate biological activity, and calibrated by dual-inlet isotope-ratio mass spectrometry. This isotopic reference material (RM), USGS46, is intended as one of two secondary isotopic reference waters for daily normalisation of stable hydrogen (δ2H) and stable oxygen (δ18O) isotopic analysis of water with a mass spectrometer or a laser absorption spectrometer. The measured δ2H and δ18O values of this reference water were −235.8 ± 0.7‰ and −29.80 ± 0.03‰, respectively, relative to VSMOW on scales normalised such that the δ2H and δ18O values of SLAP reference water are, respectively, −428 and −55.5‰. Each uncertainty is an estimated expanded uncertainty (U = 2uc) about the reference value that provides an interval that has about a 95-percent probability of encompassing the true value. This reference water is available in cases containing 144 glass ampoules that are filled with either 4 ml or 5 ml of water per ampoule.

  10. Application of δ(18)O, δ(13)CDIC, and major ions to evaluate micropollutant sources in the Bay of Vidy, Lake Geneva.

    Science.gov (United States)

    Halder, Janine; Pralong, Charles; Bonvin, Florence; Lambiel, Frederic; Vennemann, Torsten W

    2016-01-01

    Waters were sampled monthly from a profile at the wastewater outlet and a reference point in the Bay of Vidy (Lake Geneva) for a year. The samples were analyzed for (18)O/(16)O of water, (13)C/(12)C of dissolved inorganic carbon (DIC), major ions, and selected micropollutant concentrations. δ(18)O values, combined with the major ion concentrations, allowed discharged waste and storm-drainage water to be traced within the water column. On the basis of δ(18)O values, mole fractions of wastewater (up to 45 %), storm-drainage (up to 16 %), and interflowing Rhône River water (up to 34 %) could be determined. The results suggest that the stormwater fractions do not influence micropollutant concentrations in a measurable way. In contrast, the Rhône River interflow coincides with elevated concentrations of Rhône River-derived micropollutants in some profiles. δ(13)C values of DIC suggest that an increase in micropollutant concentrations at the sediment-water interface could be related to remineralization processes or resuspension.

  11. UV-laser-based microscopic dissection of tree rings - a novel sampling tool for δ(13) C and δ(18) O studies.

    Science.gov (United States)

    Schollaen, Karina; Heinrich, Ingo; Helle, Gerhard

    2014-02-01

    UV-laser-based microscopic systems were utilized to dissect and sample organic tissue for stable isotope measurements from thin wood cross-sections. We tested UV-laser-based microscopic tissue dissection in practice for high-resolution isotopic analyses (δ(13) C/δ(18) O) on thin cross-sections from different tree species. The method allows serial isolation of tissue of any shape and from millimetre down to micrometre scales. On-screen pre-defined areas of interest were automatically dissected and collected for mass spectrometric analysis. Three examples of high-resolution isotopic analyses revealed that: in comparison to δ(13) C of xylem cells, woody ray parenchyma of deciduous trees have the same year-to-year variability, but reveal offsets that are opposite in sign depending on whether wholewood or cellulose is considered; high-resolution tree-ring δ(18) O profiles of Indonesian teak reflect monsoonal rainfall patterns and are sensitive to rainfall extremes caused by ENSO; and seasonal moisture signals in intra-tree-ring δ(18) O of white pine are weighted by nonlinear intra-annual growth dynamics. The applications demonstrate that the use of UV-laser-based microscopic dissection allows for sampling plant tissue at ultrahigh resolution and unprecedented precision. This new technique facilitates sampling for stable isotope analysis of anatomical plant traits like combined tree eco-physiological, wood anatomical and dendroclimatological studies.

  12. 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.

  13. Tree-ring δ18O in African mahogany (Entandrophragma utile) records regional precipitation and can be used for climate reconstructions

    Science.gov (United States)

    van der Sleen, Peter; Groenendijk, Peter; Zuidema, Pieter A.

    2015-04-01

    The availability of instrumental climate data in West and Central Africa is very restricted, both in space and time. This limits the understanding of the regional climate system and the monitoring of climate change and causes a need for proxies that allow the reconstruction of paleoclimatic variability. Here we show that oxygen isotope values (δ18O) in tree rings of Entandrophragma utile from North-western Cameroon correlate to precipitation on a regional to sub-continental scale (1930-2009). All found correlations were negative, following the proposed recording of the 'amount effect' by trees in the tropics. The capacity of E. utile to record the variability of regional precipitation is also confirmed by the significant correlation of tree-ring δ18O with river discharge data (1944-1983), outgoing longwave radiation (a proxy for cloud cover; 1974-2011) and sea surface salinity in the Gulf of Guinea (1950-2011). Furthermore, the high values in the δ18O chronology from 1970 onwards coincide with the Sahel drought period. Given that E. utile presents clear annual growth rings, has a wide-spread distribution in tropical Africa and is long lived (> 250 years), we argue that the analysis of oxygen isotopes in growth rings of this species is a promising tool for the study of paleoclimatic variability during the last centuries in West and Central Africa.

  14. Tracking photosynthetic sulfide oxidation in a meromictic lake using sulfate δ34S and δ18O

    Science.gov (United States)

    Gilhooly, W. P.; Reinhard, C.; Lyons, T. W.; Glass, J. B.

    2012-12-01

    Phototrophic sulfur bacteria oxidize sulfide and fix carbon dioxide in the presence of sunlight without producing oxygen. Environmental conditions in the Paleo- and Mesoproterozoic, when atmospheric oxygen concentrations were at low levels and portions of the oceans were anoxic and sulfidic (euxinic), were conducive to widespread carbon fixation by anoxygenic photosynthesis. This pathway may have helped sustain euxinic conditions in the Proterozoic water column. With limited organic biomarker and geochemical evidence for widespread production of anoxygenic phototrophs, however, additional proxies are needed to fingerprint paleoecological and biogeochemical signals associated with photic zone euxinia. Paired δ34S and δ18O from ancient sulfates (gypsum, barite, or CAS) may offer an added constraint on the history and ecological dominance of photosynthetic S-oxidation. Sulfate-oxygen can fractionate during sulfate reduction, but the extent of isotopic enrichment is controlled either by kinetic isotope effects imparted during intracellular enzymatic steps or equilibrium oxygen exchange with ambient water. An improved understanding of these processes can be gained from modern natural environments. Mahoney Lake is a density-stratified lake located within the White Lake Basin of British Columbia. The euxinic water column supports a dense plate of purple sulfur bacteria (Amoebobacter purpureus) that thrives where free sulfide intercepts the photic zone at ~7 m water depth. We analyzed the isotopic composition of sulfate (δ34SSO4 and δ18OSO4), sulfide (δ34SH2S), and water (δ18OH2O) to track the potentially coupled processes of dissimilatory sulfate reduction and phototrophic sulfide oxidation within this meromictic lake. Large isotopic offsets observed between sulfate and sulfide within the monimolimnion (δ34SSO4-H2S = 51‰) and within pore waters along the oxic margin (δ34SSO4-H2S >50‰) are consistent with sulfate reduction in both the sediments and the anoxic

  15. 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

  16. The evolution of the Dead Sea brine during the last 220 ky as revealed by porewater Cl-, Na+ and δ18O in ICDP deep core

    Science.gov (United States)

    Lazar, Boaz; Levy, Elan J.; Sivan, Orit; Yechieli, Joseph; Antler, Gilad; Gavrieli, Ittai; Stein, Mordechai

    2016-04-01

    The chemical composition of pore brines extracted from 456 m long core drilled by the ICDP during 2011 in the deep basin (water depth of 300 m) of the Dead Sea provides a history of the evolution of the Dead Sea brine during the last 220 ky. The vertical profiles of chloride (Cl-) sodium (Na+) and oxygen isotopes (δ18O) in the core show that during that period the bottom water mass (hypolimnion) of the lake was always hyper-saline and its salinity did not dropped below ~70 % of that of the modern Dead Sea. The lake underwent three major hyper-arid periods that lasted altogether about 30 ky and deposited ~150 m of halite and gypsum. These periods were the last two interglacials and the postglacial till present. During the last glacial and particularly during MIS2 (~31-17 ka BP) the salinity of the lake dropped substantially due to excess input of freshwater as indicated by the decrease in Cl- and Na+ of the hypolimnion. The δ18O at the same period increased to maximum of ~7‰ (3‰ higher than today). The variations in Na+ and Cl- during the "freshening" period suggest that halite dissolution, probably due to the rise of mount Sedom diapir, "buffered" the brine from further drop in salinity. The dilution of the brine was slow and lasted more than 10 ky probably due to continuous turbulent mixing of the hypolimnion with the less saline high δ18O epilimnetic brine that underwent "normal" evaporation. The low δ18O during high salinity -halite deposition- periods is attributed to "reversed" behavior of δ18O during evaporation of high salinity brine. Massive precipitation of halite during the last 10 ky decreased sharply the Na+/Cl- ratio of the Dead Sea from ~0.7 to its present value of ~0.2. A similar low value was reached during the last interglacial, at ~120 ky. Both periods mark the most mature evaporative state of the lake during the last 220 ky.

  17. 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)

  18. 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

  19. A modern Sr/Ca-δ18O-sea surface temperature calibration for Isopora corals on the Great Barrier Reef

    Science.gov (United States)

    Brenner, Logan D.; Linsley, Braddock K.; Potts, Donald C.

    2017-02-01

    Isopora (Acroporidae) is a genus of often encrusting, branching to submassive corals that are common in many shallow habitats on modern and fossil Indo-West Pacific reefs. Although abundant, Isopora is largely absent from paleoceanographic literature. The scarcity of large Porites and the abundance of Isopora retrieved from the Great Barrier Reef (GBR) on Integrated Ocean Drilling Program Expedition 325 focused paleoceanographic attention on Isopora. Here we provide the first independent high-resolution calibration of both Sr/Ca and δ18O for temperature analyses based on Isopora and demonstrate its consistency with Porites records. We developed modern skeletal Sr/Ca- and δ18O-sea surface temperature (SST) calibrations based on five modern Isopora colonies from Heron Island in the southern GBR. Pairing the coral Sr/Ca record with monthly SST data yielded Sr/Ca-SST sensitivities from -0.061 ± 0.004 (centered) to -0.083 ± 0.007 (raw) mmol/mol °C-1 based on reduced major axis regressions. These sensitivities are in the middle of the range of published Porites values and overlap most published values for Isopora, -0.075 ± 0.011 to -0.065 ± 0.011 mmol/mol °C-1. The δ18O-SST sensitivities range from -0.184 ± 0.014 (centered) to -0.185 ± 0.014 (raw) ‰ °C-1, assuming that all seasonal variation in δ18O was due to SST. These δ18O-SST sensitivities are smaller than the widely accepted value of -0.23‰ °C-1 for biogenic aragonite but are at the upper end of high-resolution Porites-defined sensitivities that are consistently less than the aforementioned established value. Our results validate the use of Isopora as an alternative source of paleoceanographic records in habitats where large massive Porites are scarce or absent.

  20. 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

  1. 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

  2. High resolution ion microprobe investigation of the δ18O of carbonate cements (Jurassic, Paris Basin, France): New insights and pending questions

    Science.gov (United States)

    Vincent, Benoit; Brigaud, Benjamin; Emmanuel, Laurent; Loreau, Jean-Paul

    2017-04-01

    The scope of this work is to investigate, at a high resolution, the oxygen isotope composition (δ18Ocarb) of diagenetic products (synsedimentary and burial calcite cements) in shallow-marine carbonates. SIMS (Secondary Ion Mass Spectrometry) microprobe analyses were performed on thin sections from Oxfordian and Kimmeridgian Formations of the eastern Paris Basin and compared to data obtained on the same diagenetic products by conventional mass spectrometry (acid digestion). Hereby obtained, δ18O are similar, but the SIMS dataset displays a larger range of values. The isotopic zonation obtained by SIMS transects through sequences of cements filling pores, reveals an (expected) isotopic depletion from older stage synsedimentary calcites to younger stage blocky calcites and that follows the CL (cathodoluminescence) zonation. SIMS analyses however show that synsedimentary cements precipitated in intra-skeletal pores, have heavier δ18O than their inter-particle counterparts, with an offset of + 4‰V-PDB, despite similar petrographical characteristics. This difference is maintained in the δ18O of the first stages of blocky calcite cements, intra-skeletal blocky calcites showing heavier δ18O than the time equivalent and petrographically identical inter-particle calcites, with an offset of + 5‰V-PDB. These offsets are tentatively explained by the precipitation of cements under non-equilibrium conditions in intra-skeletal pores, where organic matter decay may have played a key role, acting notably on the pH. The occurrence of isolated micro-diagenetic environments, co-existing at the thin section scale, is tentatively proposed as an explanation to these small scale and high amplitude δ18O heterogeneities. These results may question the sampling strategy for future works. Microdrilling may miss the observed range of variation, but averaging the values may not necessarily lead to real misinterpretations if a critical selection of samples is performed, targeting

  3. Analysis and theoretical modeling of the 18O enriched carbon dioxide spectrum by CRDS near 1.35 μm: (I) 16O12C18O, 16O12C17O, 12C16O2 and 13C16O2

    Science.gov (United States)

    Kassi, S.; Karlovets, E. V.; Tashkun, S. A.; Perevalov, V. I.; Campargue, A.

    2017-01-01

    The room temperature absorption spectrum of 18O enriched carbon dioxide has been recorded by very high-sensitivity Cavity Ring Down spectroscopy between 6977 and 7918 cm-1 (1.43-1.26 μm). The achieved sensitivity (noise equivalent absorption αmin 8×10-11 cm-1) has allowed for the detection of more than 8600 lines belonging to 166 bands of eleven carbon dioxide isotopologues. Line intensities of the weakest observed transitions are on the order of 2×10-30 cm/molecule. In this first part, we present the results relative to the 16O12C18O, 16O12C17O, 12C16O2 and 13C16O2 isotopologues. Their absorption lines were rovibrationally assigned on the basis of the predictions of their respective effective Hamiltonian model. Overall 5476 lines were measured and assigned to 93 bands. Forty nine of them, all belonging to 16O12C18O and 16O12C17O, are reported for the first time. The studied spectral region is formed by ΔP=10-12 series of transitions, where P=2V1+V2+3V3 is the polyad number (Vi are vibrational quantum numbers). The spectroscopic parameters of 58 bands of 16O12C18O and 16O12C17O were determined from a fit of the measured line positions. An inter- and an intrapolyad resonance perturbation were identified and analyzed in the 16O12C18O spectrum. The comparison with the line positions and line intensities included in the AMES line list is discussed. Global fits of the line intensities were performed in order to (i) improve the ΔP=10 and 11 sets of the effective dipole moment parameters of 16O12C18O and the ΔP=11 set of parameters of 16O12C17O and (ii) derive for the first time the ΔP=10 and 12 parameters of 16O12C17O and 16O12C18O, respectively.

  4. 三维有序大孔复合材料H6P2W18O62/TiO2制备与多模式光催化%Preparation of three-dimensionally ordered macroporous composite H6P2W18O62/TiO2 and its photocatalytic degradation under multiple modes

    Institute of Scientific and Technical Information of China (English)

    齐云英; 李莉; 张文治; 柳迪; 王双

    2016-01-01

    Three-dimensionally ordered macroporous composite 3DOM H6 P2 W18 O62/TiO2 was prepared by the impregnation method methanol combined with polystyrene(PS)latex sphere templating technique and 3DOM TiO2 synthezed by methanol vacuum method as the canier. The phase structures,chemical composition,optical absorption properties and surface physicochemical properties were well-characterized via Fourier transform infrared spectrum(FT-IR),X-ray diffraction(XRD),UV-vis diffuse reflex spectrum(Uv-vis/DRS),X-ray photoelectron spectroscopy(XPS),Scanning electron microscopy(SEM)and N2 adsorption-desorption tests. The results showed that the primary Dawson structures remained intact in the composites,simultaneously;3DOM H6P2W18O62/TiO2 had anatase crystalline structure. The photocatalytic activities of the synthesized composite 3DOM H6P2W18O62/TiO2 were studied by the methyl orange as model molecule under multi-mode photocatalytic degradation including ultraviolet light,visible light and microwave radio. Results showed that 3DOM H6P2W18O62/TiO2 showed the best photocatalytic performance under the UV irradiation,moreover, which exhibited superior photocatalytic degradation for dyes under microwave-assisted and visible photocatalytic degradation.%采用聚苯乙烯(PS)微球做模板,以甲醇真空法制备的三维有序大孔材料(3DOM)TiO2为载体,通过浸渍法将其与多酸H6 P2 W18 O62复合制备成3DOM H6P2W18O62/TiO2.通过傅立叶-红外光谱(FT-IR)、X射线粉末衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和N2吸附-脱附等表征手段对所合成材料的光吸收性质、结构和晶相进行了表征,结果表明,3DOM H6P2W18O62/TiO2复合材料中多酸仍然保留其Dawson结构,且晶型结构以TiO2锐钛矿结构为主.为考察所合成纳米复合材料3DOM H6P2W18O62/TiO2的光催化活性,选用甲基橙为模型分子,在紫外光、可见光和微波辅射等多模式作

  5. 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+

  6. Competition for water between walnut seedlings (Juglans regia) and rye grass (Lolium perenne) assessed by carbon isotope discrimination and delta18O enrichment.

    Science.gov (United States)

    Picon-Cochard, C; Nsourou-Obame, A; Collet, C; Guehl, J M; Ferhi, A

    2001-02-01

    Container-grown walnut seedlings (Juglans regia L.) were subjected to competition with rye grass (Lolium perenne L.) and to a 2-week soil drying cycle. One and 2 weeks after the beginning of the drought treatment, H2 18O (delta approximately equals +100%) was added to the bottom layer of soil in the plant containers to create a vertical H2 18O gradient. Rye grass competition reduced aboveground and belowground biomass of the walnut seedlings by 60%, whereas drought had no effect. The presence of rye grass reduced the dry weight of walnut roots in the upper soil layer and caused a 50% reduction in lateral root length. Rye grass competition combined with the drought treatment reduced walnut leaf CO2 assimilation rate (A) and leaf conductance (gw) by 20 and 39%, respectively. Transpiration rates in rye grass, both at the leaf level and at the plant or tiller level, were higher than in walnut seedlings. Leaf intrinsic water-use efficiency (A/gw) of walnut seedlings increased in response to drought and no differences were observed between the single-species and mixed-species treatments, as confirmed by leaf carbon isotope discrimination measurements. Measurement of delta18O in soil and in plant xylem sap indicated that the presence of rye grass did not affect the vertical profile of soil water uptake by walnut seedlings. Walnut seedlings and rye grass withdrew water from the top and middle soil layers in well-watered conditions, whereas during the drought treatment, walnut seedlings obtained water from all soil layers, but rye grass took up water from the bottom soil layer only.

  7. 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).

  8. Assessing the fidelity of marine vertebrate microfossil δ18O signatures and their potential for palaeo-ecological and -climatic reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Roelofs, Brett; Barham, Milo; Cliff, John; Joachimski, Michael; Martin, Laure; Trinajstic, Kate

    2017-01-01

    Conodont biogenic apatite has become a preferred analytical target for oxygen isotope studies investigating ocean temperature and palaeoclimate change in the Palaeozoic. Despite the growing application in geochemical based palaeoenvironmental reconstructions, the paucity or absence of conodont fossils in certain facies necessitates greater flexibility in selection of robust oxygen bearing compounds for analysis. Microvertebrates offer a potential substitute for conodonts from the middle Palaeozoic. Microvertebrate bioapatite is particularly advantageous given a fossil record extending to the present with representatives across freshwater to fully marine environments, thus widening the scope of oxygen isotope studies on bioapatite. However, significant tissue heterogeneity within vertebrates and differential susceptibility of these tissues to diagenetic alteration have been raised as potential problems affecting the reliability of the oxygen isotope ratios as palaeoclimate proxies. Pristine microvertebrate and co-occurring conodont fossils from the Late Devonian and Early Carboniferous of the Lennard Shelf, Canning Basin, Western Australia, were analysed using bulk (gas isotope ratio mass spectrometry) and in-situ (secondary ion mass spectrometry) methodologies, with the latter technique allowing investigation of specific tissues within vertebrate elements. The δ18Oconodont results may be interpreted in terms of palaeolatitudinally and environmentally sensible palaeotemperatures and provide a baseline standard for comparison against δ18Omicrovertebrate values. Despite an absence of obvious diagenetic influences, GIRMS of microvertebrate denticles yielded δ18O values depleted by 2-4 ‰ relative to co-occurring conodonts. SIMS analysis of hypermineralised tissues in both scales and teeth produced δ18O values comparable with those of associated conodonts. The susceptibility of porous phosphatic fossil tissues to microbial activity, fluid interaction and

  9. 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.

    of G. sacculifer (without terminal- sacs) from 250–350 Am size-range were hand picked under microscope from 4-cm interval subsections of the cores. The crushed and cleaned tests were reacted with 100% phosphoric acid at 60F1 8C in a reaction vessel..., the fluctuations of ~F0.5 8C occur within each climate period. A 0.5 8C SST variation is equivalent to ~0.1x change in the y 18 O G. sacculifer (Duplessy et al., 1981). Further, the Uk 37 -SST estimates contain certain uncertainty depending upon the calibration...

  10. 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.

  11. 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.

  12. 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.; J. W. Wenninger; S. Uhlenbrook

    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...

  13. 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.

  14. Assessing multi-site δ18O-climate calibrations of the coralline alga Clathromorphum across the high-latitude Northern Hemisphere

    Science.gov (United States)

    Ng, Jessica Y.; Williams, Branwen; Thompson, Diane M.; Mayne, Chloe; Halfar, Jochen; Edinger, Evan; Johnson, Kathleen

    2016-12-01

    An increased number of climate proxy records and more refined interpretation of proxy data are crucial to improve projections of future climate at high latitudes, where internal feedbacks amplify warming and established high-resolution climate archives are especially sparse. Encrusting coralline algae are being developed as a mid- to high-latitude marine climate archive. These long-lived algae form a solid high-Mg calcite skeleton with annual growth bands similar to those of trees and tropical corals. The oxygen isotope ratio of the algal skeleton (δ18Oalg) records local environmental and climatic factors, notably sea surface temperature and seawater δ18O. Here we assess the δ18Oalg-climate relationship in diverse environments across the algal habitat range utilizing two species of coralline algae from the genus Clathromorphum. Clathromorphum is widely distributed from the cold-temperate North Atlantic and Pacific to the Arctic Ocean and has recently yielded numerous climate reconstructions of up to 650 years in length. In this study, we calibrate δ18Oalg of four specimens to gridded temperature and salinity data, the latter a proxy for seawater δ18O. These specimens were collected from a variety of algal growth environments across the high-latitude Northern Hemisphere: two specimens from the Aleutian Archipelago, one from the Canadian Arctic, and one from the Gulf of Maine. Low winter temperatures and insolation restrict the months when algae record local climate in the δ18O of their skeletons; we therefore determine these response seasons by correlating monthly temperature and salinity anomalies with annual δ18Oalg anomalies at each site. We then average gridded data over months that correlate significantly (95% confidence interval) for regression with δ18Oalg. While the timing and nature of the climate signal vary across sites, we find significant relationships between δ18Oalg and either temperature or salinity averaged over the response season at three

  15. Late Pleistocene climatic change in the French Jura (Gigny) recorded in the δ 18O of phosphate from ungulate tooth enamel

    Science.gov (United States)

    Fabre, Magali; Lécuyer, Christophe; Brugal, Jean-Philip; Amiot, Romain; Fourel, François; Martineau, François

    2011-05-01

    Oxygen isotope compositions of phosphate in tooth enamel from large mammals (i.e. horse and red deer) were measured to quantify past mean annual air temperatures and seasonal variations between 145 ka and 33 ka in eastern France. The method is based on interdependent relationships between the δ 18O of apatite phosphate, environmental waters and air temperatures. Horse ( Equus caballus germanicus) and red deer ( Cervus elaphus) remains have δ 18O values that range from 14.2‰ to 17.2‰, indicating mean air temperatures between 7°C and 13°C. Oxygen isotope time series obtained from two of the six horse teeth show a sinusoidal-like signal that could have been forced by temperature variations of seasonal origin. Intra-tooth oxygen isotope variations reveal that at 145 ka, winters were colder (- 7 ± 2°C) than at present (3 ± 1°C) while summer temperatures were similar. Winter temperatures mark a well-developed West-East thermal gradient in France of about - 9°C, much stronger than the -4°C difference recorded presently. Negative winter temperatures were likely responsible for the extent and duration of the snow cover, thus limiting the food resources available for large ungulates with repercussions for Neanderthal predators.

  16. 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.

  17. Quantitative Proteome Analysis of Breast Cancer Cell Lines using 18O-Labeling and an Accurate Mass and Time Tag Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Patwardhan, Anil J.; Strittmatter, Eric F.; Camp, David G.; Smith, Richard D.; Pallavicini, Maria

    2006-05-01

    Proteome comparison of cell lines derived from breast cancer and normal breast epithelium provide opportunities to identify differentially expressed proteins and pathways associated with specific phenotypes. We employed trypsin-catalyzed 16O/18O peptide labeling, FTI-CR mass spectrometry, and the accurate mass and time (AMT) tag strategy to calculate compare the relative protein abundances of hundreds of proteins simultaneously in non-cancer and cancer cell lines derived from breast tissue. A reference panel of cell lines was created to facilitate comparisons of relative protein abundance amongst multiple cell lines and across multiple experiments. A peptide database generated from multidimensional LC separations and MS/MS analysis was used to facilitate subsequent AMT tag-based peptide identifications. This peptide database represented a total of 2,299 proteins, including 514 that were quantified using the AMT tag and 16O/18O strategies. Eighty-six proteins showed at least a 3-fold protein abundance change between cancer and non-cancer cell lines. A comparison of protein expression profiles with previously published gene expression data revealed that 21 of these proteins also had >3-fold differences between the non-cancer and cancer cell lines at the transcriptional level. Clustering of protein abundance ratios revealed that several groups of proteins were differentially expressed between the cancer cell lines

  18. 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.

  19. 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...

  20. 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.

  1. Dual sources of water overprinting on the low zircon δ18O metamorphic country rocks: Disequilibrium constrained through inverse modelling of partial reequilibration

    Science.gov (United States)

    Wei, Chun-Sheng; Zhao, Zi-Fu

    2017-01-01

    Since water is only composed of oxygen and hydrogen, δ18O and δ2H values are thus utilized to trace the origin of water(s) and quantify the water-rock interactions. While Triassic high pressure (HP) and ultrahigh pressure (UHP) metamorphic rocks across the Dabie-Sulu orogen in central-eastern China have been well documented, postcollisional magmatism driven hydrothermal systems are little known. Here we show that two sources of externally derived water interactions were revealed by oxygen isotopes for the gneissic country rocks intruded by the early Cretaceous postcollisional granitoids. Inverse modellings indicate that the degree of disequilibrium (doD) of meteoric water interactions was more evident than that of magmatic one (−65 ± 1o vs. −20 ± 2°); the partial reequilibration between quartz and alkali feldspar oxygen isotopes with magmatic water was achieved at 340 °C with a water/rock (W/R) ratio of about 1.2 for an open-hydrothermal system; two-stage meteoric water interactions were unraveled with reequilibration temperatures less than 300 °C and W/R ratios around 0.4. The lifetime of fossil magmatic hydrothermal system overprinted on the low zircon δ18O orthogneissic country rocks was estimated to maintain up to 50 thousand years (Kyr) through oxygen exchange modellings. Four-stage isotopic evolutions were proposed for the magmatic water interacted gneiss. PMID:28091552

  2. 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.

  3. Ba6-3 x Nd8+2 x Ti18O54 Tungsten Bronze: A New High-Temperature n-Type Oxide Thermoelectric

    Science.gov (United States)

    Azough, Feridoon; Freer, Robert; Yeandel, Stephen R.; Baran, Jakub D.; Molinari, Marco; Parker, Stephen C.; Guilmeau, Emmanuel; Kepaptsoglou, Demie; Ramasse, Quentin; Knox, Andy; Gregory, Duncan; Paul, Douglas; Paul, Manosh; Montecucco, Andrea; Siviter, Jonathan; Mullen, Paul; Li, Wenguan; Han, Guang; Man, Elena A.; Baig, Hasan; Mallick, Tapas; Sellami, Nazmi; Min, Gao; Sweet, Tracy

    2016-03-01

    Semiconducting Ba6-3 x Nd8+2 x Ti18O54 ceramics (with x = 0.00 to 0.85) were synthesized by the mixed oxide route followed by annealing in a reducing atmosphere; their high-temperature thermoelectric properties have been investigated. In conjunction with the experimental observations, atomistic simulations have been performed to investigate the anisotropic behavior of the lattice thermal conductivity. The ceramics show promising n-type thermoelectric properties with relatively high Seebeck coefficient, moderate electrical conductivity, and temperature-stable, low thermal conductivity; For example, the composition with x = 0.27 (i.e., Ba5.19Nd8.54Ti18O54) exhibited a Seebeck coefficient of S 1000K = 210 µV/K, electrical conductivity of σ 1000K = 60 S/cm, and thermal conductivity of k 1000K = 1.45 W/(m K), leading to a ZT value of 0.16 at 1000 K.

  4. A paleothermometer based on abundances of 13C-18O bonds in bioapatite: Calibration and reconstruction of the body temperatures of extinct Cenozoic mammals and Mesozoic dinosaurs

    Science.gov (United States)

    Eagle, R.; Schauble, E. A.; Tripati, A. K.; Fricke, H. C.; Tuetken, T.; Eiler, J. M.

    2009-12-01

    The stable isotope compositions of biologically precipitated apatite in bone, teeth, and scales are widely used to obtain information on the diet, behavior, and physiology of extinct organisms, and to reconstruct past climate in terrestrial and marine settings. Here we report the application of a new type of geochemical measurement to bioapatite, a ‘clumped isotope’ thermometer based on the thermodynamically driven preference for 13C and 18O to bond with each other within carbonate ions in the crystal lattice of apatite. This effect is dependent on temperature but unlike conventional stable isotope paleotemperature proxies, is independent from the isotopic composition of water from which the mineral formed. We show that the abundance of 13C-18O bonds in the carbonate component of apatite from modern teeth is proportional to the body temperature of the organism, with an accuracy of 1-2oC, and that the empirical calibration is supported by a theoretical model of isotopic ordering. We also report initial paleothermometry results from analyses of Cenozoic fossil mammal teeth and Mesozoic dinosaur teeth. Therefore, clumped isotope analysis of bioapatite represents a new approach in the study of the physiology of extinct species by allowing the first relatively assumption-free measurement of their body temperatures. It will also open new avenues in the study of paleoclimate, as the measurements of clumped isotopes in apatite from fossils, such as conodonts and brachiopods, as well as phosphorites, have the potential to record environmental temperatures.

  5. 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.

  6. Dual sources of water overprinting on the low zircon δ18O metamorphic country rocks: Disequilibrium constrained through inverse modelling of partial reequilibration

    Science.gov (United States)

    Wei, Chun-Sheng; Zhao, Zi-Fu

    2017-01-01

    Since water is only composed of oxygen and hydrogen, δ18O and δ2H values are thus utilized to trace the origin of water(s) and quantify the water-rock interactions. While Triassic high pressure (HP) and ultrahigh pressure (UHP) metamorphic rocks across the Dabie-Sulu orogen in central-eastern China have been well documented, postcollisional magmatism driven hydrothermal systems are little known. Here we show that two sources of externally derived water interactions were revealed by oxygen isotopes for the gneissic country rocks intruded by the early Cretaceous postcollisional granitoids. Inverse modellings indicate that the degree of disequilibrium (doD) of meteoric water interactions was more evident than that of magmatic one (-65 ± 1o vs. -20 ± 2°) the partial reequilibration between quartz and alkali feldspar oxygen isotopes with magmatic water was achieved at 340 °C with a water/rock (W/R) ratio of about 1.2 for an open-hydrothermal system; two-stage meteoric water interactions were unraveled with reequilibration temperatures less than 300 °C and W/R ratios around 0.4. The lifetime of fossil magmatic hydrothermal system overprinted on the low zircon δ18O orthogneissic country rocks was estimated to maintain up to 50 thousand years (Kyr) through oxygen exchange modellings. Four-stage isotopic evolutions were proposed for the magmatic water interacted gneiss.

  7. 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.

  8. Synthesis and Characterization of Composite H6 P2 Mo18 O62/Zn(BDC) (Bipy) 0. 5 and Its Adsorption Activity for Methylene Blue%H6 P2 Mo18 O62/Zn(BDC)(Bipy)0.5复合材料的合成、表征及对亚甲基蓝的吸附

    Institute of Scientific and Technical Information of China (English)

    龚文朋; 田超强; 杜晓刚; 杨水金

    2016-01-01

    By employing the H6P2Mo18O62, terephthalic acid(H2BDC), 4,4'-bipyridine(Bipy) to assemble with Zn2+ ion, a three-dimensional ( 3D ) metal organic framework composite, named H6 P2 Mo18 O62/Zn( BDC) ( Bipy) 0. 5 , was synthesized. The composition, structure, morphology, stability and toleration of H6P2Mo18O62/Zn(BDC)(Bipy)0.5 were characterized by X-ray powder diffraction pattern(XRD), Fourier transform infrared(FTIR) spectrum, scanning electron microscopy(SEM), thermogravimetric(TG) analysis and N2 adsorption-desorption analysis. The adsorption of methylene blue ( MB ) onto H6 P2 Mo18 O62/Zn( BDC) ( Bipy) 0. 5 in aqueous solution was studied. The effects of the experimental parameters including the temperature, the initial pH value and initial concentration of methylene blue solution were discussed. The ex-perimental data could be well described by the Langmuir equations and pseudo-second-order kinetic model. The adsorption process of methylene blue on the composite was spontaneous and exothermic. Furthermore, we also explored the adsorption properties of H6 P2 Mo18 O62/Zn( BDC) ( Bipy) 0. 5 to methyl violet, malachite green, rhodamine B, and methyl orange. The results indicated that this new absorbent showed better adsorption per-formance towards cationic dyes.%在溶剂热条件下,以H6P2Mo18O62、对苯二甲酸(H2BDC)、4,4'-联吡啶(Bipy)和硝酸锌为原料构筑了1个三维金属有机骨架复合材料 H6 P2 Mo18 O62/Zn ( BDC )( Bipy )0.5,并采用红外光谱( IR )、 X 射线衍射( XRD)、扫描电子显微镜( SEM)、热重分析( TG)、N2吸附-脱附等手段对产物进行了表征.同时,研究了产物对水溶液中亚甲基蓝( MB)的吸附性能,并探讨了MB初始pH值、初始浓度和温度对吸附量的影响.结果表明,产物的等温吸附模型符合 Langmuir 等温吸附模型,动力学符合拟二级动力学. H6 P2 Mo18 O62/Zn( BDC)( Bipy)0.5对亚甲基蓝的吸附是自发和放热的,此外,产物对甲基紫、罗丹明B

  9. 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%.

  10. Differential cross section measurements of {sup 27}Al(p,p{sup /}γ){sup 27}Al and {sup 27}Al(p,αγ){sup 24}Mg reactions in the energy range of 1.6–3.0 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Jokar, A., E-mail: arezajokar@gmail.com [Physics & Accelerators Research School, NSTRI, PO Box 14395-836, Tehran (Iran, Islamic Republic of); Kakuee, O.; Lamehi-Rachti, M. [Physics & Accelerators Research School, NSTRI, PO Box 14395-836, Tehran (Iran, Islamic Republic of); Sharifzadeh, N. [Payame Noor University, PO Box 19395-13697, Tehran (Iran, Islamic Republic of); Fathollahi, V. [Physics & Accelerators Research School, NSTRI, PO Box 14395-836, Tehran (Iran, Islamic Republic of)

    2015-11-01

    In this work measurement of differential cross sections of {sup 27}Al(p,p{sup /}γ){sup 27}Al (E{sub γ} = 844, 1014 keV) and {sup 27}Al(p,αγ){sup 24}Mg (E{sub γ} = 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/cm{sup 2} Al onto a 129 μg/cm{sup 2} 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%.

  11. 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.

  12. 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

  13. 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

  14. Molecular Radiation of {13CO (J=1-0) and C18O (J=1-0) from OMC--3%OMC--3的13CO(1--0)和C18O(1--0)分子辐射

    Institute of Scientific and Technical Information of China (English)

    孙锦; 宋丽敏; 张燕平; 张海燕

    2000-01-01

    13CO (J=1-0) and C18O (J=1-0)emissions of the OMC--3 in the Orion Amolecular cloud were mapped with the 13.7 m millimeter wave telescopeof Purple Mountain Observatory using a higher spatial resolution. Theoverall structure of the cloud and the average physical parameters of all the 13CO (J=1-0)and C18O (J=1-0) cores are derived. We find that the cores are well associated withthe youngest objects --- class 0 sources: MMS1, MMS4, MMS6 with the 13CO core centers and MMS7, MMS8, MMS9 with the C18O core centers. The velocity structure is also analyzed for the whole OMC--3 region. There is a 1.7 km/s velocity gradient from south tonorth connecting the 13CO (J=1-0) and C18O (J=1-0) cores. And the redshifted clumps are consistently to the north, and the blushifted clumps, to the south of OMC--3. Star formation in the region is also discussed.%利用紫金山天文台青海站的13.7 m毫米波望远镜,对Orion A 分子云中的OMC--3区域, 进行了较高分辨率的13CO(J=1-0)和C18O(J=1-0)分子辐射的成图观测. 给出了该分子云中13CO和 C18O云核分布的整体结构和平均物理参数.观测发现, 该分子云的13CO和 C18O的云核中心分别与最年轻的天体---Class 0类源MMS1, MMS4, MMS6和MMS7, MMS8, MMS9成协. 此外,通过分析OMC--3整个区域的速度场结构,发现沿C18O和13CO云核方向从南到北有一个 1.7 km/s 的速度场梯度,而分子云的红、蓝移团块则分别趋于云的北部和南部. 并对OMC--3区的恒星形成特征进行了讨论.

  15. 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。

  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

    2016-06-07

    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. Integrated in situ U-Pb Age and Hf-O Analyses of Zircon from the Northern Yangtze Block: New Insights into the Neoproterozoic Low-δ18O Magmas in the South China Block

    Science.gov (United States)

    Yang, Y. N.; Wang, X. C.; Li, Q. L.; Li, X. H.

    2015-12-01

    The oxygen isotopic composition of Neoproterozoic magmas from the northern Yangtze Block holds a key for the origin of large-scale 18O depletion in the HP and UHP metamorphic rocks in the Dabie-Sulu orogenic belt, northern margin of the South China Block. We report here the integrated in situ U-Pb dating and O-Hf isotope analyses of zircon grains from sedimentary and volcanic rocks of the late Neoproterozoic Suixian Group (SG) from the northern Yangtze Block. Detrital zircon grains display age peaks of 0.73-0.74 Ga, 0.79 Ga, and 2.0 Ga. Zircon U-Pb ages together with Hf-O isotopic composition indicate provenance of SG dominantly from proximal Neoproterozoic igneous rock and likely hidden Paleoproterozoic basement along the northern margin of the Yangtze Block. The zircon δ18O values from SG range from 10.5‰ to 1.3‰. Zircon grains with negative δ18O value, typical result of magma-ice interaction, were not identified in this study. The major phase of low-δ18O (< 4‰) magmas initiated at ca. 780 Ma, long before the first glaciation event (< 715 Ma) in the South China Block. Thus caution should be taken when using low-δ18O zircon grains to infer cold climate. Low-δ18O zircon grains have large ranges of ɛHf(t) values, varying from -15.5 to 10.7, concentrating on negative ɛHf(t). This strongly argues against the possibility that the low-δ18O magma was produced by partial melting of high-temperature hydrothermally altered oceanic crust because this model predicted MORB-like Hf isotopes for the resultant low-δ18O magmas. This study emphasizes that high-T water-rock interaction and continental rifting tectonic setting are essential to generate abundant low-δ18O magmas. The important application of our study is to confirm that most of negative-δ18O zircons identified in HP and UHP metamorphic rocks may not have been inherited from their Neoproterozoic protoliths.

  18. 2H NMR and 13C-IRMS analyses of acetic acid from vinegar, 18O-IRMS analysis of water in vinegar: international collaborative study report.

    Science.gov (United States)

    Thomas, Freddy; Jamin, Eric

    2009-09-01

    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 delta13C (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 thousand, and the average reproducibility (R) was 0.91 per thousand. 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 (delta13C and delta18O) and allows a satisfactory discrimination of vinegar types. The precision parameters of the method for measuring delta18O were found to be similar to the values previously obtained for other methods applied to wine and

  19. 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

  20. 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

  1. 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

  2. Effect of in-stream physicochemical processes on the seasonal variations in δ13C and δ18O values in laminated travertine deposits in a mountain stream channel

    Science.gov (United States)

    Yan, Hao; Liu, Zaihua; Sun, Hailong

    2017-04-01

    Travertines are potential archives of continental paleoclimate. Records of stable carbon and oxygen isotopic composition (δ13C and δ18O) in laminated travertine deposits from endogene spring waters show regular cyclic patterns which may be due to seasonal change in climate determinants such as temperature and rainfall. In this study, δ13C and δ18O measurements of three travertine specimens that grew naturally over the eight years, 2004-2011, at upstream, middle and downstream sites in a canal at Baishuitai, SW China, are presented. They exhibit clear seasonal variations that generally correlate with biannual laminations. Specifically, δ13C and δ18O values show significant positive correlation with each other for the three travertine specimens, with the correlation coefficients increasing downstream along the canal. To reveal the factors governing the seasonal and spatial variations in δ13C and δ18O values, newly formed travertines precipitated on Plexiglas substrates are also examined. Both δ13C and δ18O of the substrate travertines are low in the summer/rainy season and high in the winter/dry season, showing a great consistency with the patterns in the natural travertines. Spatially, isotope values increase downstream in both seasons, with higher increase rates in winter that are related to removal of larger fractions of dissolved inorganic carbon (DIC) from the solution and stronger kinetic isotopic fractionation in winter. Due to in-stream physicochemical processes, including CaCO3 precipitation and the associated degassing of CO2, seasonal changes in δ13C and δ18O in the travertines are amplified by two times between the upstream and downstream sites: this is opposite to trends for epigene (meteogene) tufas whose seasonal changes in stable isotope compositions are reduced downstream. We suggest in-stream physicochemical processes are a potential reason for underestimation of annual temperature ranges that are inferred from epigene tufa δ18O data.

  3. Synthesis and voltammetry of [bmim]4[alpha-S2W18O62] and related compounds: rapid precipitation and dissolution of reduced surface films.

    Science.gov (United States)

    Mariotti, Andrew W A; Xie, Jingli; Abrahams, Brendan F; Bond, Alan M; Wedd, Anthony G

    2007-04-02

    1-n-Butyl-3-methylimidazolium (bmim) salts of [alpha-SiM12O40]4- and [alpha-S2M18O62]4- (M = Mo, W) were synthesized and characterized. In sharp contrast to the multiple one-electron diffusion-controlled reduction processes expected in solution at a glassy carbon electrode, reduction of these salts beyond the one-electron level in CH3CN (0.1 M [bmim][PF6]) led to rapid precipitation of arrays of microdroplets or microcrystals onto the surface. Upon oxidation these arrays dissolved on the electrochemical time scale, resulting in voltammograms displaying both diffusion-controlled and surface-confined behavior. These novel observations appear to be related to the ability of the [bmim]+ cations and polyoxometalate anions to form ion clusters in solution and to the lower solubilities of the reduced salts.

  4. Proof in climatology for circulation effect of stalagmite δ18O in East Asia: analysis on the ratios among water vapor transport passageway intensities in East Asia

    Science.gov (United States)

    Nan, S.; Tan, M.; Zhao, P.

    2013-07-01

    Further verification about the circulation effect of stalagmite δ18O in East Asian monsoon region needs the quantitative description for the proportion of water vapor transport (WVT) from different source regions. WVT passageway intensities are defined as regionally averaged WVT flux modes in this paper. The ratio between two WVT passageways' intensities represents relative intensity of the two WVT passageways. Using the NCEP-NCAR reanalysis data for 1948-2011, the ratios of the intensities of three WVT passageways from low latitudes (the intensity of WVT from Bay of Bengal (IBOB), the intensity of WVT from South China Sea (ISCS) and the intensity of WVT from western North Pacific (IWNP) in summer are calculated. SB is for the ISCS-IBOB ratio, WB for the IWNP-IBOB ratio, and WS for the IWNP-ISCS ratio. The decadal increase occurs in the time series of WB and WS, with higher values in 1976-1995 and lower values in 1950-1975, probably resulting from the strengthening of WVT from WNP in the midterm of 1970s. East Asian atmospheric circulations, WVTs and previous SST characters corresponding to the ratios are analyzed. The result indicates that SB, WB and WS may properly reflect the relative intensities between ISCS and IBOB, between IWNP and IBOB, and between IWNP and ISCS, respectively. For high SB years, the Asian Low and the western Pacific subtropical high (WPSH) weaken. The southwesterly winds from BOB to the Yangtze River valley by the southeast of the Tibetan Plateau weaken and the WVT from BOB to East Asia weakens. The southwesterly winds from SCS to East Asia strengthen and the WVT from SCS to East Asia strengthens. In high WB years, the Asian Low weakens and the WPSH shifts westwards, enhances and enlarges. The WVT from WNP to East Asia increases because of the strengthening of the easterly winds on the south of the WPSH. The westerly winds from BOB to East Asia by Indo-China Peninsula decrease and the WVT from BOB to East Asia weakens. The atmospheric

  5. Proof in climatology for circulation effect of stalagmite δ18O in East Asia: analysis on the ratios among water vapor transport passageway intensities in East Asia

    Directory of Open Access Journals (Sweden)

    S. Nan

    2013-07-01

    Full Text Available Further verification about the circulation effect of stalagmite δ18O in East Asian monsoon region needs the quantitative description for the proportion of water vapor transport (WVT from different source regions. WVT passageway intensities are defined as regionally averaged WVT flux modes in this paper. The ratio between two WVT passageways' intensities represents relative intensity of the two WVT passageways. Using the NCEP-NCAR reanalysis data for 1948–2011, the ratios of the intensities of three WVT passageways from low latitudes (the intensity of WVT from Bay of Bengal (IBOB, the intensity of WVT from South China Sea (ISCS and the intensity of WVT from western North Pacific (IWNP in summer are calculated. SB is for the ISCS-IBOB ratio, WB for the IWNP-IBOB ratio, and WS for the IWNP-ISCS ratio. The decadal increase occurs in the time series of WB and WS, with higher values in 1976–1995 and lower values in 1950–1975, probably resulting from the strengthening of WVT from WNP in the midterm of 1970s. East Asian atmospheric circulations, WVTs and previous SST characters corresponding to the ratios are analyzed. The result indicates that SB, WB and WS may properly reflect the relative intensities between ISCS and IBOB, between IWNP and IBOB, and between IWNP and ISCS, respectively. For high SB years, the Asian Low and the western Pacific subtropical high (WPSH weaken. The southwesterly winds from BOB to the Yangtze River valley by the southeast of the Tibetan Plateau weaken and the WVT from BOB to East Asia weakens. The southwesterly winds from SCS to East Asia strengthen and the WVT from SCS to East Asia strengthens. In high WB years, the Asian Low weakens and the WPSH shifts westwards, enhances and enlarges. The WVT from WNP to East Asia increases because of the strengthening of the easterly winds on the south of the WPSH. The westerly winds from BOB to East Asia by Indo-China Peninsula decrease and the WVT from BOB to East Asia weakens

  6. 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.

  7. Modélisation du transport des isotopes stables de l'eau (18O et D) dans le cas d'un sol nu en conditions naturelles

    OpenAIRE

    Melayah, A.; Bruckler, L; Bariac, T.

    1996-01-01

    Nous proposons dans ce travail un modèle mécaniste de prévision du comportement des isotopes stables de l'eau (18O et 2H) dans le système sol atmosphère soumis à des conditions climatiques quelconques. Les principales caractéristiques du modèle sont le couplage entre les flux dans le sol et dans l'atmosphère par l'intermédiaire du bilan d'énergie à la surface du sol et de la convection turbulente dans les basses couches atmosphériques, la prise en compte simultanée des flux isotopiques diffus...

  8. 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 depthsphotorespiration, 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.

  9. 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.

  10. 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.

  11. A Survey of \\delta18O and \\delta15N Ratios in Ground Water from an Agricultural Community in the San Joaquin Valley, California

    Science.gov (United States)

    Glowacki, S. D.; Suen, C. J.

    2004-12-01

    We studied ground water samples from domestic and monitoring wells in an agricultural community in the eastern side of the San Joaquin Valley, California. The study area is rich in alluvial soils creating an extremely fertile farmland. Livestock farms and agricultural fields are abundant in the area. Fifty-four ground water samples were analyzed for \\delta18O and \\delta15N in dissolved nitrate, in addition to nutrients and major minerals. Nitrate concentration levels in groundwater are elevated and affected by agricultural and other activities. Possible sources of nutrients include: a municipal waste-water treatment facility, a raisin processing plant, a meat processing plant, a turkey farm, diary operations, and agricultural fields. However, except for the turkey farm and a diary, we found no statistical significant contribution of nitrate from the other facilities as compared to the rest of the area. The \\delta18O versus \\delta15N ratios plot of dissolved ground water nitrate shows most samples clustered around an area consistent with soil organic nitrogen. In addition, the rest of the samples show a trend that is indicative of denitrification process. Generally, high \\delta15N values are associated with low nitrate concentrations. The isotopic signal of denitrification is particularly pronounced in samples in the vicinity of the waste water treatment facility, where the highest values of \\delta15N and the lowest nitrate concentrations are observed. However, these samples also have elevated chloride concentrations indicating a waste-water source. These data suggest that the denitrification in the subsurface may have been enhanced by bacteria species introduced by the effluence of the plant. [This study was performed with the collaboration of Steven R Silva of USGS, Menlo Park, and Iris Yamagata and Holly Jo Ferrin of California Department of Water Resources.

  12. Estimating the glacial melt water contribution to the fresh water budget from salinity and δ18O measurements in Godthåbsfjord

    Science.gov (United States)

    Fitzner, Antje; van As, Dirk; Bendtsen, Jorgen; Dahl-Jensen, Dorthe; Fettweis, Xavier; Mortensen, John; Rysgaard, Soren

    2013-04-01

    The mass loss of the Greenland ice sheet increases due to changes in the surface mass balance and accelerated ice discharge through numerous outlet glaciers at the margins. The melt has global and local consequences. Globally the sea level rises and locally the increased fresh water inflow affects fishery and transportation. In this study we focus on the fjord system near Nuuk in West Greenland, Godthåbsfjord. Godthåbsfjord is a unique fjord with its length of about 300 km and a shallow sill at the fjord entrance that protects the fjord system. There are several tidewater glaciers terminating into the fjord and two land-terminating glaciers along the fjord contributing to the fresh water content in the fjord. The largest tidewater glacier is Kangiata Nunåta Sermia. The freshwater originates primarily from three processes: surface melt, ice berg calving and basal melt. Observations and climate models can give estimates for calving and surface melt. Basal melt, however, cannot be observed directly. Even though mass loss by basal melting is neglected on the global scale, it plays an important role in the small regional environment like fjords and the glaciers itself. Warmer ocean temperatures increase basal melt, and resulting lubrication accelerates tidewater glaciers. Overall, the freshwater content in the fjord increases. Salinity measurements taken in the fjord between 2007 and 2011 show a seasonal variability originating from the variation in fresh water inflow. Based on salinity records only, it is not possible to distinguish between the different fresh water sources like precipitation and melt. Hence, δ18O measurements are used in addition to salinity records to determine the origin of the fresh water because of the different δ18O signatures of run-off and glacial melt water. The resulting fresh water inflow and the glacial melt contribution are compared to independent estimates and regional climate model output.

  13. 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.

  14. 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.

  15. 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.

  16. Properties of Dense Cores Embedded in Musca Derived from Extinction Maps and 13CO, C18O, and NH3 Emission Lines

    Science.gov (United States)

    Machaieie, Dinelsa A.; Vilas-Boas, José W.; Wuensche, Carlos A.; Racca, Germán A.; Myers, Philip C.; Hickel, Gabriel R.

    2017-02-01

    Using near-infrared data from the Two Micron All Sky Survey catalog and the Near Infrared Color Excess method, we studied the extinction distribution in five dense cores of Musca, which show visual extinction greater than 10 mag and are potential sites of star formation. We analyzed the stability in four of them, fitting their radial extinction profiles with Bonnor–Ebert isothermal spheres, and explored their properties using the J = 1–0 transition of 13CO and C18O and the J = K = 1 transition of NH3. One core is not well described by the model. The stability parameter of the fitted cores ranges from 4.5 to 5.7 and suggests that all cores are stable, including Mu13, which harbors one young stellar object (YSO), the IRAS 12322-7023 source. However, the analysis of the physical parameters shows that Mu13 tends to have larger A V, n c, and P ext than the remaining starless cores. The other physical parameters do not show any trend. It is possible that those are the main parameters to explore in active star-forming cores. Mu13 also shows the most intense emission of NH3. Its 13CO and C18O lines have double peaks, whose integrated intensity maps suggest that they are due to the superposition of clouds with different radial velocities seen in the line of sight. It is not possible to state whether these clouds are colliding and inducing star formation or are related to a physical process associated with the formation of the YSO.

  17. 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.

  18. 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.

  19. UV-laser microdissection system - A novel approach for the preparation of high-resolution stable isotope records (δ13C/δ18O) from tree rings

    Science.gov (United States)

    Schollaen, Karina; Helle, Gerhard

    2013-04-01

    Intra-annual stable isotope (δ13C and δ18O) studies of tree rings at various incremental resolutions have been attempting to extract valuable seasonal climatic and environmental information or assessing plant ecophysiological processes. For preparing high-resolution isotope samples normally wood segments or cores are mechanically divided in radial direction or cut in tangential direction. After mechanical dissection, wood samples are ground to a fine powder and either cellulose is extracted or bulk wood samples are analyzed. Here, we present a novel approach for the preparation of high-resolution stable isotope records from tree rings using an UV-laser microdissection system. Firstly, tree-ring cellulose is directly extracted from wholewood cross-sections largely leaving the wood anatomical structure intact and saving time as compared to the classical procedure. Secondly, micro-samples from cellulose cross-sections are dissected with an UV-Laser dissection microscope. Tissues of interest from cellulose cross-sections are identified and marked precisely with a screen-pen and dissected via an UV-laser beam. Dissected cellulose segments were automatically collected in capsules and are prepared for stable isotope (δ13C and δ18O) analysis. The new techniques facilitate inter- and intra-annual isotope analysis on tree-ring and open various possibilities for comparisons with wood anatomy in plant eco-physiological studies. We describe the design and the handling of this novel methodology and discuss advantages and constraints given by the example of intra-annual oxygen isotope analysis on tropical trees.

  20. 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

  1. 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.

  2. Assessment of enzymatic methods in the δ18O value determination of the L-tyrosine p-hydroxy group for proof of illegal meat and bone meal feeding to cattle.

    Science.gov (United States)

    Tanz, Nicole; Werner, Roland A; Eisenreich, Wolfgang; Schmidt, Hanns-Ludwig

    2011-09-14

    The δ(18)O value of the p-hydroxy group of L-tyrosine depends on the biosynthesis by plants or animals, respectively. In animal proteins it reflects the diet and is therefore an absolute indicator for illegal feeding with meat and bone meal. The aim of this investigation was to perform the positional (18)O determination on L-tyrosine via a one-step enzymatic degradation. Proteins from plants, herbivores, omnivores, and carnivores were characterized by their δ(13)C, δ(15)N, and δ(18)O values, the latter for normalizing the positional δ(18)O values. Their L-tyrosine was degraded by tyrosine phenol lyase to phenol, analyzed as (2,4,6)-tribromophenol. Degradation by tyrosine decarboxylase yielded tyramine. The δ(18)O values of both analytes corresponded to the trophic levels of their sources but were not identical, probably due to an isotope effect on the tyrosine phenol lyase reaction. Availability of the enzyme, easy control of the reaction, and isolation of the analyte are in favor of tyrosine decarboxylase degradation as a routine method.

  3. Environmental inferences by stable isotopes ({sup 13} C and {sup 18} O) and ages of amazon forest natural trees; Inferencias ambientais a partir dos isotopos estaveis ({sup 13} C e {sup 18} O) e idades de arvores naturais da floresta amazonica

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Marcelo Z.

    1988-09-01

    Qualitative interpretations of recent past climate ({+-} 500 years) in the Amazon basin - a region were no instrumental records for the main climate parameters exits over the last 70 years - were surveyed based on the isotopic variation of the C-13 and O-18 contents in cellulose isolated from natural trees. Trees from terra firme and low and flat land alongside water course environments had their ages estimated using radiocarbon method extrapolated from growth rates obtained from atmospheric CO{sub 2} activities. Tree ages from 60 to 600 years were found. Analysis of the cellulose material {sup 18} O content was performed by mass spectrometry. (author). 96 refs., 20 figs., 5 tabs.

  4. 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.

  5. 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

  6. High Resolution δ18O and δ13C Records of AMS 14C Dated Stalagmites From Jinlun and Yilingyan Caves in Guangxi, China: Climate Variability and Controlling Factors in the Monsoonal Region During the Past 2300 Years

    Science.gov (United States)

    Li, H. C.; Lien, W. Y.; Mii, H. S.; Jiang, G. H.; Chou, C. Y.; Chou, P. J.

    2015-12-01

    Jinlun Cave in Mashan County and Yilingyan Cave in Wuming County are ~120km and ~60km north of Nanning in Guangxi Province under influence of both Indian Monsoon and North Western Pacific Monsoon. Several stalagmites have been dated by AMS 14C dating method since 230Th/U is not applicable due to very low U contents. Twenty (20) AMS 14C dates on Stalagmite JL20131005-10 (10-cm long) show "Bomb carbon curve", spanning the past 60 years. Lamination counting further confirms the chronology. Thirty nine (39) AMS 14C dates on Stalagmite JL20131005-12 (33-cm long) reveal 2300-year continuous growth. Stalagmite YLY20130727-12 (10-cm long) from Yilingyan Cave covers a continuous record of past 2300 years. All studied stalagmites in the caves contain low dead carbon fractions. The annual resolution δ18O and δ13C records obtained from the stalagmites allow us to compare the stalagmite δ18O records with the instrumental rainfall and temperature records, Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI), and Sunspot variation, etc. The δ18O and δ13C records exhibit relatively good correlation throughout the time, indicating climatic control on vegetation change. Based on the high-resolution δ18O and δ13C records, we interpret that dry climatic conditions and poor vegetation coverage during periods of AD1880~1850, 1700~1600, 1460~1320, 1210~1280, 860~750, 540~420, 300~220, and AD100~0 shown by increased δ18O and δ13C. The δ18O and δ13C were strongly depleted during the Medieval Warm Period (MWP between AD900 and AD1100) and Current Warm Period (CWP, since AD1900), reflecting strongly increased East Asian Summer Monsoon. After AD1900, the δ13C decreased about 6‰, perhaps indicating human impact on surface vegetation. The δ18O records from the study area are comparable to the published WX42B δ18O record of Wanxiang Cave (Zhang et al., 2008) except for the period of AD1400~1850. Our study suggests that AMS 14C dating is an alternative method for

  7. GC-ECNICI-MS/MS of eicosanoids as pentafluorobenzyl-trimethylsilyl (TMS) derivatives: Evidence of CAD-induced intramolecular TMS ether-to-ester rearrangement using carboxy-(18)O-labelled eicosanoids and possible implications in quantitative analysis.

    Science.gov (United States)

    Tsikas, Dimitrios

    2017-03-15

    GC-MS and GC-MS/MS of pentafluorobenzyl (PFB) ester trimethylsilyl (TMS) ether (PFB-TMS) derivatives of hydroxylated long-chain fatty acids including arachidonic acid metabolites, the eicosanoids, in the electron-capture negative-ion chemical ionization (ECNICI) mode are the most sensitive and accurate approaches to quantify carboxyl groups-containing compounds in complex biological fluids such as plasma and urine. Under ECNICI conditions, PFB-TMS derivatives of eicosanoids ionize to form very few ions, with the carboxylates [M-PFB](-) being typically the most intense. Less intense ions may be additionally formed by consecutive neutral loss (NL) of trimethylsilanol (TMSOH, 90Da) groups ([M-PFB-(TMSOH)n](-)). By using [1,1-(18)O2]- and [1,ω-(18)O2]-eicosanoids, we studied ion processes following collisionally activated dissociation (CAD) of the precursor ions [M-PFB](-). We found that CAD resulted in formation of product ions due to NL of a TMS(18)OH (92Da) group in monocarboxylic and of a PFB(18)OH (200Da) group in dicarboxylic eicosanoids. TMS(18)OH NL implies an intra-molecular transfer of the TMS group from hydroxyl groups to their carboxylate anions [M-PFB](-). From a mechanistic point of view, this rearrangement may explain formation of unique product ions in GC-MS/MS of eicosanoids under ECNICI conditions. From the quantitative point of view, quantification by GC-MS/MS of product ions due to [M-PFB-(TMSOH)n](-) and [M-PFB-TMS(18)OH-(TMSOH)n-1](-)would reveal incorrect data, if [1,1-(18)O2]-eicosanoids are used as internal standards and if no correction for the (18)O-loss is performed. In (18)O-labelled dicarboxylic eicosanoids, such as the major urinary metabolite (MUM) of E prostaglandins, i.e., [1,ω-(18)O2]-PGE-MUM), no TMS ester/TMS ether rearrangement was observed. Yet, (18)O-loss occurred upon CAD of [M-PFB](-) due to NL of PFB(18)OH (200Da). In both cases the extent of (18)O-loss needs to be determined and considered for accurate quantification of

  8. Assessing the impact of diagenesis on δ11B, δ13C, δ18O, Sr/Ca and B/Ca values in fossil planktic foraminiferal calcite

    Science.gov (United States)

    Edgar, Kirsty M.; Anagnostou, Eleni; Pearson, Paul N.; Foster, Gavin L.

    2015-10-01

    The geochemical composition of foraminiferal tests is a valuable archive for the reconstruction of paleo-climatic, -oceanographic and -ecological changes. However, dissolution of biogenic calcite and precipitation of inorganic calcite (overgrowth and recrystallization) at the seafloor and in the sediment column can potentially alter the original geochemical composition of the foraminiferal test, biasing any resulting paleoenvironmental reconstruction. The δ11B of planktic foraminiferal calcite is a promising ocean pH-proxy but the effect of diagenesis is still poorly known. Here we present new δ11B, δ13C, δ18O, Sr/Ca and B/Ca data from multiple species of planktic foraminifera from time-equivalent samples for two low latitude sites: clay-rich Tanzanian Drilling Project (TDP) Site 18 from the Indian Ocean containing well-preserved ('glassy') foraminifera and carbonate-rich Ocean Drilling Program (ODP) Site 865 from the central Pacific Ocean hosting recrystallized ('frosty') foraminifera. Our approach makes the assumption that environmental conditions were initially similar at both sites so most chemical differences are attributable to diagenesis. Planktic foraminiferal δ18O and δ13C records show offsets in both relative and absolute values between the two sites consistent with earlier findings that these isotopic ratios are strongly influenced by diagenetic alteration. Sr/Ca and B/Ca ratios in planktic foraminiferal calcite are also offset between the two sites but there is little change in the relative difference between surface and deep dwelling taxa. In contrast, δ11B values indicate no large differences between well-preserved and recrystallized foraminifera suggesting that despite extensive diagenetic alteration the δ11B of biogenic calcite appears robust, potentially indicative of a lack of free exchange of boron between pore fluids and the recrystallizing CaCO3. Our finding may remove one potential source of uncertainty in δ11B based p

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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 (tracers, otherwise would have supported the suitability of

  14. 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

  15. 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

  16. High precision measurement by mass spectrometry of isotopic ratios {delta} {sup 13}C and {delta}{sup 18}O of carbon dioxide; Mesure haute precision par spectrometrie de masse des rapports isotopiques {delta} {sup 13}C et {delta}{sup 18}O du dioxyde de carbone

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, Chr.; Ciais, Ph.

    1998-02-01

    Carbon dioxide (CO{sub 2}) is the second natural greenhouse gas in the Earth's atmosphere, after vapor water. Its concentration levels have been increasing by 25% due to human activities over the past 200 years, thus increasing the radiative forcing at the surface and potentially including major climate change for the next centuries. It is of primary importance to better quantify the role of carbon contained into the oceans and the land biota in moderating the anthropic perturbation. To do so, {sup 13}C and {sup 18}O isotopes are unique tools which allow to estimate indirectly the terrestrial CO{sub 2} fluxes based on atmospheric measurements. The present reports describes the experimental set-up used at the CFR-LMCE laboratory to measure the {sup 13}C and {sup 18}O natural abundance in atmospheric carbon dioxide. This technique requires high levels of both precision and accuracy because the geochemical signal nevertheless consists of very small changes in isotopic composition (on the order of 0.01 permits). Also, given the large number of samples to analyses routinely, it must be run in an automatic mode. Our experiment design consists of 'extraction line' where CO{sub 2} is separated cryogenically from the air, which is coupled to a (Finnigan MAT 252) mass spectrometer. (authors)

  17. 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.

  18. 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.

  19. 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.

  20. Modeling precipitation δ18O variability in East Asia since the Last Glacial Maximum: temperature and amount effects across different timescales

    Science.gov (United States)

    Wen, Xinyu; Liu, Zhengyu; Chen, Zhongxiao; Brady, Esther; Noone, David; Zhu, Qingzhao; Guan, Jian

    2016-11-01

    Water isotopes in precipitation have played a key role in the reconstruction of past climate on millennial timescales and longer. However, for midlatitude regions like East Asia with complex terrain, the reliability behind the basic assumptions of the temperature effect and amount effect is based on modern observational data and still remains unclear for past climate. In the present work, we reexamine the two basic effects on seasonal, interannual, and millennial timescales in a set of time slice experiments for the period 22-0 ka using an isotope-enabled atmospheric general circulation model (AGCM). Our study confirms the robustness of the temperature and amount effects on the seasonal cycle over China in the present climatic conditions, with the temperature effect dominating in northern China and the amount effect dominating in the far south of China but no distinct effect in the transition region of central China. However, our analysis shows that neither temperature nor amount effect is significantly dominant over China on millennial and interannual timescales, which is a challenge to those classic assumptions in past climate reconstruction. Our work helps shed light on the interpretation of the proxy record of δ18O from a modeling point of view.

  1. 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...

  2. Nitrate sources and dynamics in the salinized rivers and estuaries – a δ15N- and δ18O-NO3– isotope approach

    Directory of Open Access Journals (Sweden)

    D. Xue

    2014-03-01

    Full Text Available To trace NO3– sources and assess NO3– dynamics in the salinized rivers and estuaries, three rivers (HH River, CB River and JY River and two estuaries (HH Estuary and CJ Estuary along the Bohai Bay (China have been selected to determine DIN and δ15N and δ18O-NO3–. Upstream of the HH River NO3– was removed 30.9 ± 22.1% by aerobic denitrification, resulting from effects of the floodgate: limiting water exchange with downstream and prolonging water residence time to remove NO3–. Downstream of the HH River NO3– was removed 2.5 ± 13.3% by NO3– turnover processes. Conversely, NO3– was increased 36.6 ± 25.2% by external N source addition in the CB River and 34.6 ± 35.1% by in-stream nitrification in the JY River, respectively. The HH and CY Estuaries behaved mostly conservative excluding the sewage input in the CJ Estuary. Hydrodynamics in estuaries have been changed by the ongoing reclamation projects, aggravating the estuaries losing the attenuation function of NO3–.

  3. A C2-symmetric antimonato polyoxovanadate cluster [V16Sb4O42(H2O)](8-) derived from the {V18O42} archetype.

    Science.gov (United States)

    Antonova, Elena; Näther, Christian; Kögerler, Paul; Bensch, Wolfgang

    2012-06-21

    The new antimonato polyoxovanadate [V(IV)(16)Sb(III)(4)O(42)(H(2)O)](8-) cluster (1a) is the main structural motif of the solvothermally obtained compound {(trenH(2))Zn(tren)}(2)[V(16)Sb(4)O(42)(H(2)O)]·xH(2)O (x = 6-10) (1) (tren = tris(2-aminoethyl)amine). The C(2)-symmetric cluster structure is closely related to the {V(18)O(42)} archetype. 1 crystallizes in the monoclinic space group C2/c with a = 30.7070(19) Å, b = 13.9512(5) Å, c = 23.1435(14) Å, β = 128.076(6)°, and V = 7804.8(7) Å(3). The orientation of the [Sb(III)(2)O(5)](4-) groups in each cluster leads to intermolecular Sb···O contacts and the formation of channels between the clusters. [Zn(tren)(trenH(2))] complexes with trigonal bipyramidal coordination environments are located between the [V(16)Sb(4)O(42)(H(2)O)](8-) anions, and form a three dimensional network with them via strong N-H···O hydrogen bonds. Up to 250 °C crystal water molecules are emitted, which are reversibly incorporated in humid air.

  4. Stretched-state excitations with the (p,n) reaction at 135 MeV on [sup 14]C, [sup 18]O and [sup 30]Si

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, L.A.

    1992-01-01

    Neutron time-of-flight spectra were obtained for the [sup 14]C(p,n)[sup 14]N, [sup 18]O(p,n)[sup 18]F, and [sup 30]Si(p,n)[sup 30]P reactions at 135 MeV with the beam-swinger system at the Indiana University Cyclotron Facility. Excitation-energy spectra and the differential cross sections for the observed excitations in these reactions were extracted over the momentum transfer range from 0 to 2.7 fm[sup [minus]1]. The goal of this work was to obtain the strengths and distributions for the stretched states. The identification of these states was based on comparisons of the theoretical differential cross sections, performed in a DWIA formalism, with the experimental cross sections. Isospin assignments were based on comparison of the measured (p,n) and (e,e[prime]) spectroscopic strengths. Candidate ([pi]d[sub 5/2],[nu]p[sub 3/2][sup [minus]1]), J[sup pi] = 4[sup [minus

  5. 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.

  6. Improvement of thermoelectric properties of Bi{sub 2}Sr{sub 2}Co{sub 1}.8O{sub x} through solution synthetic methods

    Energy Technology Data Exchange (ETDEWEB)

    Torres, M. A.; Sotelo, A.; Raskeh, S. H.; Serrano, I.; Constantinescu, C.; Madre, M. A.; Diez, J. C.

    2012-07-01

    Several solution synthetic methods, sol-gel and a polymeric route, have been studied in order to obtain Bi{sub 2}Sr{sub 2}Co{sub 1}.8O{sub x} ceramics with improved thermoelectric properties, compared to the classical solid state reaction. The products obtained by these different methods have been compared using DTA-TGA, powder X-ray diffraction, scanning electron microscopy, and thermoelectric characterizations. All the samples obtained by solution synthesis show higher homogeneity and lower content of secondary phases. The main differences in thermo electrical properties are due to the decrease of electrical resistivity in samples obtained by solution methods, compared with the solid state obtained samples. Between them, the decrease is especially high for those samples prepared by the polymer solution method. Therefore, the polymeric solution synthesis route is shown to yield a power factor four times higher than the obtained for the solid state and sol-gel methods at room temperature. (Author) 17 refs.

  7. Demonstration of the applicability of 3D Slicer to Astronomical Data Using 13CO and C18O Observations of IC348

    CERN Document Server

    Borkin, M A; Goodman, A A; Halle, M; Borkin, Michelle A.; Ridge, Naomi A.; Goodman, Alyssa A.; Halle, Michael

    2005-01-01

    3D Slicer, a brain imaging and visualization computer application developed at Brigham and Women's Hospital's Surgical Planning Lab, was used to visualize the IC 348 star-forming complex in Perseus in RA-DEC-Velocity space. This project is part of a collaboration between Harvard University's Astronomy Department and Medical School, and serves as a proof-of-concept technology demonstration for Harvard's Institute for Innovative Computing (IIC). 3D Slicer is capable of displaying volumes (data cubes), slices in any direction through the volume, 3D models generated from the volume, and 3D models of label maps. The 3D spectral line maps of IC 348 were created using 13CO and C18O data collected at the FCRAO (Five College Radio Astronomy Observatory). The 3D visualization makes the identification of the cloud's inner dense cores and velocity structure components easier than current conventional astronomical methods. It is planned for 3D Slicer to be enhanced with astrophysics-specific features resulting in an astro...

  8. 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.

  9. 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.

  10. Line parameters for the 01111-00001 band of {sup 12}C{sup 16}O{sup 18}O from SOIR measurements of the Venus atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Wilquet, V. [Belgian Institute for Space Aeronomy, 3 av. Circulaire, B-1180 Brussels (Belgium)], E-mail: valerie.wilquet@aeronomie.be; Mahieux, A.; Vandaele, A.C. [Belgian Institute for Space Aeronomy, 3 av. Circulaire, B-1180 Brussels (Belgium); Perevalov, V.I.; Tashkun, S.A. [Institute of Atmospheric Optics, Akademitcheskii av., 1, 634055 Tomsk (Russian Federation); Fedorova, A.; Korablev, O. [Space Research Institute (IKI), 84/32 Profsoyuznaya, 117810 Moscow (Russian Federation); Montmessin, F.; Dahoo, R.; Bertaux, J.-L. [Service d' Aeronomie du CNRS, BP3, 91371, Verrieres-le-Buisson (France); Universite Pierre et Marie Curie, Paris (France); Institut Pierre Simon Laplace, Universite de Versailles-Saint-Quentin, 78 Saint Quentin en Yvelines (France)

    2008-04-15

    CO{sub 2} is the major constituent of the atmosphere of Venus. Absorption lines due to its {sup 12}C{sup 16}O{sup 18}O isotopologue have been observed for the first time in Venus spectra in the 2930-3015 cm{sup -1} spectral region, where the HITRAN database does not contain any line from this isotopologue. The measurements were performed by the SOIR instrument, which is part of the SPICAV/SOIR instrument on board the Venus Express mission of ESA. SOIR measured the atmospheric transmission of the upper atmosphere of Venus (z>70 km) by performing a solar occultation experiment using the atmosphere as a gigantic absorption cell. The identification of this newly observed band was first made recently from Mars atmosphere observations by US colleagues. We have made independent theoretical calculations of the positions of the lines of this new 01111-00001 absorption band, which coincide perfectly with the positions of the observed lines. Assuming an oxygen isotopic ratio similar to the one measured previously in the lower atmosphere of Venus, the line strengths of each observed line are deduced and listed.

  11. 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.

  12. 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.

  13. Prospects of heavy and superheavy element production via inelastic nucleus-nucleus collisions - from 238U+238U to18O+254Es

    Science.gov (United States)

    Schädel, Matthias

    2016-12-01

    Multi-nucleon transfer reactions, frequently termed deep-inelastic, between heavy-ion projectiles and actinide targets provide prospects to synthesize unknown isotopes of heavy actinides and superheavy elements with neutron numbers beyond present limits. The 238U on 238U reaction, which revealed essential aspects of those nuclear reactions leading to surviving heavy nuclides, mainly produced in 3n and 4n evaporation channels, is discussed in detail. Positions and widths of isotope distributions are compared. It is shown, as a general rule, that cross sections peak at irradiation energies about 10% above the Coulomb barrier. Heavy target nuclei are essential for maximizing cross sections. Experimental results from the 238U on 248Cm reaction, including empirical extrapolations, are compared with theoretical model calculations predicting relatively high cross sections for neutron-rich nuclei. Experiments to test the validity of such predictions are proposed. Comparisons between rather symmetric heavy-ion reactions like 238U on 248Cm (or heavier targets up to 254Es) with very asymmetric ones like 18O on 254Es reveal that the ones with 238U as a projectile have the highest potential in the superheavy element region while the latter ones can be advantageous for the synthesis of heavy actinide isotopes. Concepts for highly efficient recoil separators designed for transfer products are presented.

  14. 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.

  15. First high resolution analysis of the 2ν1, 2ν3, and ν1 + ν3 bands of S18O2

    Science.gov (United States)

    Ulenikov, O. N.; Bekhtereva, E. S.; Gromova, O. V.; Zamotaeva, V. A.; Sklyarova, E. A.; Sydow, C.; Maul, C.; Bauerecker, S.

    2016-12-01

    We report the results of a highly accurate, (1-3)×10-4 cm-1, ro-vibrational analysis of the S18O2 molecule in the spectral region of 2100-2700 cm-1. More than 2910, 2130, and 1390 transitions belonging to the 2ν1, ν1 +ν3, and 2ν3 bands were assigned for the first time with the values of quantum numbers Jmax. /Kamax . equal to 67/26, 81/25 and 53/16, respectively. The weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account Coriolis resonance interactions between the vibrational states (v1v2v3) and (v1 ∓ 1v2v3 ± 1) and Fermi interactions between the states (v1v2v3) and (v1 ∓ 1v2 ± 2v3). To make the ro-vibrational analysis physically more suitable, the initial values of main spectroscopic parameters have been estimated theoretically. Finally, the set of 43 spectroscopic parameters obtained from the fit reproduces values of 2384 initial "experimental" ro-vibrational energy levels (more than 6430 transitions assigned in the experimental spectra) with the rms = 1.74 ×10-4cm-1.

  16. Consistently dated records from the Greenland GRIP, GISP2 and NGRIP ice cores for the past 104 ka reveal regional millennial-scale δ18O gradients with possible Heinrich event imprint

    DEFF Research Database (Denmark)

    Seierstad, Inger Kathrine; Abbott, Peter M.; Bigler, Matthias

    2014-01-01

    NGRIP, GRIP, and GISP2 are generally very similar and display synchronous behaviour at climate transitions. The δ18O differences between Summit and NGRIP, however, changed slowly over the Last Glacial–Interglacial cycle and also underwent abrupt millennial-to-centennial-scale variations. We suggest...

  17. The δ(18) O and δ(2) H of water in the leaf growth-and-differentiation zone of grasses is close to source water in both humid and dry atmospheres.

    Science.gov (United States)

    Liu, Hai Tao; Schäufele, Rudi; Gong, Xiao Ying; Schnyder, Hans

    2017-04-03

    The oxygen and hydrogen isotope composition of water in the leaf growth-and-differentiation zone, LGDZ, (δ(18) OLGDZ , δ(2) HLGDZ ) of grasses influences the isotopic composition of leaf cellulose (oxygen) and wax (hydrogen) - important for understanding (paleo)environmental and physiological information contained in these biological archives - but is presently unknown. This work determined δ(18) OLGDZ and δ(2) HLGDZ , (18) O- and (2) H-enrichment of LGDZ (∆(18) OLGDZ and ∆(2) HLGDZ ), and the (18) O- and (2) H-enrichment of leaf blade water (∆(18) OLW, ∆(2) HLW ) in two C3 and three C4 grasses grown at high and low vapor pressure deficit (VPD). The proportion of unenriched water (px ) in the LGDZ ranged from 0.9 to 1.0 for (18) O and 1.0 to 1.2 for (2) H. VPD had no effect on the proportion of (18) O- and (2) H-enriched water in the LGDZ, and species effects were small or nonsignificant. Deuterium discrimination caused depletion of (2) H in LGDZ water, increasing (apparent) px -values > 1.0 in some cases. The isotopic composition of water in the LGDZ was close to that of source water, independent of VPD and much less enriched than previously supposed, but similar to reported xylem water in trees. The well-constrained px will be useful in future investigations of oxygen and hydrogen isotopic fractionation during cellulose and wax synthesis, respectively.

  18. Hydrothermal alteration and melting of the crust during the Columbia River Basalt-Snake River Plain transition and the origin of low-δ18O rhyolites of the central Snake River Plain

    Science.gov (United States)

    Colón, Dylan P.; Bindeman, Ilya N.; Ellis, Ben S.; Schmitt, Axel K.; Fisher, Christopher M.

    2015-05-01

    We present compelling isotopic evidence from ~15 Ma rhyolites that erupted coeval with the Columbia River Basalts in southwest Idaho's J-P Desert and the Jarbidge Mountains of northern Nevada at that suggests that the Yellowstone mantle plume caused hydrothermal alteration and remelting of diverse compositions of shallow crust in the area where they erupted. These rhyolites also constitute the earliest known Miocene volcanism in the vicinity of the Bruneau-Jarbidge and Twin Falls (BJTF) volcanic complexes, a major center of voluminous (103-104 km3) low-δ18O rhyolitic volcanism that was previously defined as being active from 13 to 6 Ma. The Jarbidge Rhyolite has above-mantle δ18O18O of +7.9‰ SMOW) and extremely unradiogenic εHf (- 34.7) and εNd (- 24.0). By contrast, the J-P Desert units are lower in δ18O (+4.5 to 5.8‰), and have more moderately unradiogenic whole-rock εHf (- 20.3 to - 8.9) and εNd (- 13.4 to - 7.7). The J-P Desert rhyolites are geochemically and petrologically similar to the younger rhyolites of the BJTF center (the one exception being their high δ18O values), suggesting a common origin for J-P Desert and BJTF rhyolites. The presence of low-δ18O values and unradiogenic Nd and Hf isotopic compositions, both of which differ greatly from the composition of a mantle differentiate, indicate that some of these melts may be 50% or more melted crust by volume. Individual J-P Desert units have isotopically diverse zircons, with one lava containing zircons ranging from - 0.6‰ to + 6.5‰ in δ18O and from - 29.5 to - 2.8 in εHf. Despite this diversity, zircons all have Miocene U/Pb ages. The range of zircon compositions fingerprints the diversity of their source melts, which in turn allow us to determine the compositions of two crustal end-members which melted to form these rhyolites. These end-members are: 1) Archean basement with normal to high-δ18O and unradiogenic εHf and 2) hydrothermally altered, shallow, young crust with low

  19. 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.

  20. The Investigation of Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54) Microwave Dielectric Ceramics%Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)系微波介电陶瓷的研究

    Institute of Scientific and Technical Information of China (English)

    王爽

    2009-01-01

    研究了Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)(x=0~1)陶瓷微波性能,并对其微观机理和晶体结构进行分析.随Bi_2O_3含量的增加,系统介电常数(ε)迅速增大,品质因数与频率的乘积(Q·f)逐渐减小.掺入Bi_2O_3后,系统中出现具有高ε的Bi_4Ti_3O_(12)晶相,并形成了类填满型钨青铜结构,阳离子极化增强,因此ε随Bi_2O_3含量的增加而增大.实验表明,当y=0.25~0.3时,Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)(x =0~1) 陶瓷具有优良的微波介电性能,其主要工艺条件和性能参数为烧结温度1 200 ℃保温4 h,ε≈102~107,Q·f≈20 000~22 000 GHz(1 GHz测量), 容量温度系数|α_c|<10×10~(-6)/℃.%The microwave properties of Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)(x =0~1)system were investigated,and the micro-mechanism and the crystal structure were analyzed.The results indicated that the dielectric constant increased greatly while the Q·f value decreased with the increase of Bi_2O_3 content.These phenomena were related to the appearance of a new phase Bi_4Ti_3O_(12),which has high dielectric constant. Besides, full-filled tungsten bronze-like structure should be formed,the polarization of positive ions were enhanced.So,the samples doped with Bi_2O_3 presented higher dielectric constant.The experimental results showed that Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54) ceramics exhibited excellent microwave dielectric properties at y=0.25~0.3.The main technological conditions and the parameters were as follows: the sintering temperature of 1 200 ℃,the holding time of 4 h,ε≈102~107,Q·f≈20 000~22 000 GHz(Measured at 1 GHz) and the capacity-temperature coefficient of |α_c|<10×10~(-6)/℃.

  1. 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

  2. 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.

  3. {sup 18}O{sub 2} label mechanism of sulfur generation and characterization in properties over mesoporous Sm-based sorbents for hot coal gas desulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B.S., E-mail: bingsiliu@tju.edu.cn [Department of Chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Wan, Z.Y.; Wang, F.; Zhan, Y.P. [Department of Chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Tian, M.; Cheung, A.S.C. [Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (China)

    2014-02-01

    Graphical abstract: - Highlights: • Formation of sulfur originated from catalytic action of samarium oxysulfide. • Mechanism of sulfur desorption was first confirmed via time of flight MS. • Utilization of mesoporous Sm-based sorbents was favorable for diffusion of H{sub 2}S. • Stability of Sm-based sorbent correlated with reasonable regeneration procedure. - Abstract: Using a sol–gel method, SmMeO{sub x}/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 H{sub 2}S from hot coal gas were reported for the first time. The results of successive sulfidation/regeneration cycles revealed that SmFeO{sub 3}/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 Sm{sub 2}O{sub 2}S species, which was confirmed for the first time via high sensitive time of flight mass spectrometer (TOF-MS) using 6%vol{sup 18}O{sub 2}/Ar regeneration gas and can reduce markedly procedural complexity. The sorbents were characterized using N{sub 2}-adsorption, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), temperature-programmed reduction of H{sub 2} (H{sub 2}-TPR), thermogravimetry (TG) and time-of-flight mass spectrometry (TOF-MS) techniques.

  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 setup a one-week field campaign for comparing measurements of the ambient isotope signals from the L1115-i and WVIA systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. Using this field measurement data we address the question of how well the deuterium excess (d=δ2H-8δ18O) of atmospheric water vapour can be determined with laser spectroscopy. The deuterium excess is an interesting parameter for process-based atmospheric water cycle studies, which depends on humidity and temperature conditions at source location of water vapour. Up to now only very few high-time-resolution measurements of deuterium excess exist. Our concurrent measurements of atmospheric isotopes in water vapour

  5. Measuring variations of δ18O and δ2H in atmospheric water vapour using two commercial laser-based spectrometers: an instrument characterisation study

    Science.gov (United States)

    Aemisegger, F.; Sturm, P.; Graf, P.; Sodemann, H.; Pfahl, S.; Knohl, A.; Wernli, H.

    2012-07-01

    Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic and mesoscale meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here 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 Research). The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the 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. Based on the experience from our laboratory experiments, we set up a one-week field campaign for comparing measurements of the ambient isotope signals from the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3‰ for δ2H, 0.5‰ for δ18O and 3.1‰ for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric water cycle and

  6. Growth decline and divergent tree ring isotopic composition (δ(13) C and δ(18) O) contradict predictions of CO2 stimulation in high altitudinal forests.

    Science.gov (United States)

    Gómez-Guerrero, Armando; Silva, Lucas C R; Barrera-Reyes, Miguel; Kishchuk, Barbara; Velázquez-Martínez, Alejandro; Martínez-Trinidad, Tomás; Plascencia-Escalante, Francisca Ofelia; Horwath, William R

    2013-06-01

    Human-induced changes in atmospheric composition are expected to affect primary productivity across terrestrial biomes. Recent changes in productivity have been observed in many forest ecosystems, but low-latitude upper tree line forests remain to be investigated. Here, we use dendrochronological methods and isotopic analysis to examine changes in productivity, and their physiological basis, in Abies religiosa (Ar) and Pinus hartwegii (Ph) trees growing in high-elevation forests of central Mexico. Six sites were selected across a longitudinal transect (Transverse Volcanic Axis), from the Pacific Ocean toward the Gulf of Mexico, where mature dominant trees were sampled at altitudes ranging from 3200 to 4000 m asl. A total of 60 Ar and 84 Ph trees were analyzed to describe changes in growth (annual-resolution) and isotopic composition (decadal-resolution) since the early 1900s. Our results show an initial widespread increase in basal area increment (BAI) during the first half of the past century. However, BAI has decreased significantly since the 1950s with accentuated decline after the 1980s in both species and across sites. We found a consistent reduction in atmosphere to wood (13) C discrimination, resulting from increasing water use efficiency (20-60%), coinciding with rising atmospheric CO2 . Changes in (13) C discrimination were not followed, however, by shifts in tree ring δ(18) O, indicating site- and species-specific differences in water source or uptake strategy. Our results indicate that CO2 stimulation has not been enough to counteract warming-induced drought stress, but other stressors, such as progressive nutrient limitation, could also have contributed to growth decline. Future studies should explore the distinct role of resource limitation (water vs. nutrients) in modulating the response of high-elevation ecosystems to atmospheric change.

  7. 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.

    2016-12-01

    Using Atacama Large Millimeter/submillimeter Array 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 parametrization 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 towards 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 10-7 M⊙ 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.

  8. Measuring variations of δ18O and δ2H in atmospheric water vapour using laser spectroscopy: an instrument characterisation study

    Directory of Open Access Journals (Sweden)

    S. Pfahl

    2012-02-01

    Full Text Available Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here 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 Research. The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the 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. Based on the experience from our laboratory experiments we set up a one-week field campaign for comparing measurements of the ambient isotope signals of the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3‰ for δ2H, 0.5‰ for δ18O and 3.1‰ for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric water cycle and the

  9. Measuring variations of δ18O and δ2H in atmospheric water vapour using two commercial laser-based spectrometers: an instrument characterisation study

    Directory of Open Access Journals (Sweden)

    S. Pfahl

    2012-07-01

    Full Text Available Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic and mesoscale meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here 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 Research. The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the 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. Based on the experience from our laboratory experiments, we set up a one-week field campaign for comparing measurements of the ambient isotope signals from the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3‰ for δ2H, 0.5‰ for δ18O and 3.1‰ for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric

  10. Impact of traffic on δ15N, δ13C and δ18O of needles and annual tree rings of Norway spruce (Picea abies L.

    Directory of Open Access Journals (Sweden)

    Guerrieri MR

    2006-01-01

    Full Text Available Increase of nitrogen depositions, as oxidized (NOx and reduced (NHx compounds, has important implications on ecosystem nitrogen cycle. NOx comes predominantly from fossil fuel combustion in car engines and industrial processes, while agricultural activities (cattle farming, fertilizations are the main sources for NHx emissions. Such fertilisations could stimulate growth and, therefore, productivity of forests, especially in temperate forests, where nitrogen is a limiting factor. On the other hand an excess of nitrogen can lead to an acidification of the soil and have a negative impact on the microbial fauna and structure of plants. NOx and NHx depositions can be separated with the help of stable isotopes with different 15N-values reported for NOx originating from combustion sources. Consequently it was observed that the nitrogen isotopic composition of the vegetation reflects the isotopic signature of nitrogen sources. Our preliminary results on needles of Norway spruce trees exposed to NOx emissions along a transect perpendicular to a highway close to Faido and Brittnau show a clear isotopic enrichment in 15N in trees growing closer to traffic pollution, indicating an uptake of atmospheric nitrogen by stomatal pathway. Carbon and oxygen isotopic composition measured in tree rings reveals the physiological response in plants. Trees more exposed to air pollution from traffic show an increase in δ13C and δ18O in tree rings, since mid sixties next to Erstfeld. This could mean a higher photosynthetic activity, enhanced by NOx traffic emissions, under low or not changed stomatal conductance. Our results confirm that stable isotopes of carbon, oxygen and nitrogen measured in needles and tree rings represent an important tool to monitor the impact of NOx load on tree physiology.

  11. Application of a newly identified and characterized 18-o-acyltransferase in chemoenzymatic synthesis of selected natural and nonnatural bioactive derivatives of phoslactomycins.

    Science.gov (United States)

    Ghatge, Mohini S; Palaniappan, Nadaraj; Alhamadsheh, Ma'moun M; DiBari, Jessica; Reynolds, Kevin A

    2009-06-01

    Phoslactomycins (PLMs) and related leustroducsins (LSNs) have been isolated from a variety of bacteria based on antifungal, anticancer, and other biological assays. Streptomyces sp. strain HK 803 produces five PLM analogs (PLM A and PLMs C to F) in which the C-18 hydroxyl substituent is esterified with a range of branched, short-alkyl-chain carboxylic acids. The proposed pathway intermediate, PLM G, in which the hydroxyl residue is not esterified has not been observed at any significant level in fermentation, and the only route to this potentially useful intermediate has been an enzymatic deacylation of other PLMs and LSNs. We report that deletion of plmS(3) from the PLM biosynthetic cluster gives rise to a mutant which accumulates the PLM G intermediate. The 921-bp plmS(3) open reading frame was cloned and expressed as an N-terminally polyhistidine-tagged protein in Escherichia coli and shown to be an 18-O acyltransferase, catalyzing conversion of PLM G to PLM A, PLM C, and PLM E using isobutyryl coenzyme A (CoA), 3-methylbutyryl-CoA, and cyclohexylcarbonyl-CoA, respectively. The efficiency of this process (k(cat) of 28 +/- 3 min(-1) and K(m) of 88 +/- 16 microM) represents a one-step chemoenzymatic alternative to a multistep synthetic process for selective chemical esterification of the C-18 hydroxy residue of PLM G. PlmS(3) was shown to catalyze esterification of PLM G with CoA and N-acetylcysteamine thioesters of various saturated, unsaturated, and aromatic carboxylic acids and thus also to provide an efficient chemoenzymatic route to new PLM analogs.

  12. Evidence of the chemical reaction of (18)O-labelled nitrite with CO2 in aqueous buffer of neutral pH and the formation of (18)OCO by isotope ratio mass spectrometry.

    Science.gov (United States)

    Tsikas, Dimitrios; Böhmer, Anke; Gros, Gerolf; Endeward, Volker

    2016-05-01

    Inorganic nitrite (NO2(-), ON-O(-) ←→ (-)O-NO) is the autoxidation product of nitric oxide (NO). Nitrite can also be formed from inorganic nitrate (ONO2(-)), the major oxidation product of NO in erythrocytes, by the catalytic action of bacterial nitrate reductase in gut and oral microflora. Nitrite can be reduced to NO by certain cellular proteins and enzymes, as well as in the gastric juice under acidic conditions. Hemoglobin, xanthine oxidoreductase and carbonic anhydrase (CA) have been reported to convert nitrite to NO. Renal CA isoforms are involved in the reabsorption of nitrite and may, therefore, play an important role in NO homeostasis. Yet, the mechanisms underlying the action of CA on nitrite are incompletely understood. The nitrate/nitrite system is regarded as a reservoir of NO. We have recently shown that nitrite reacts chemically with carbon dioxide (CO2), the regular substrate of CA. The present communication reports a stable isotope ratio mass spectrometry (IRMS) study on the reaction of NO2(-) and CO2 performed in 50 mM HEPES buffer of pH 7.4 at 37 °C. By using (18)O-labelled nitrite ((18)ON-O(-)/(-18)O-NO) and CO2 we observed formation of (18)O-labelled CO2. This finding is an unequivocal evidence of the chemical reaction of (18)ON-O(-)/(-18)O-NO with CO2. The reaction is rapid and involves nucleophilic attack of the negatively charged nitrite via one of its oxygen atoms on the partially positively charged CO2 molecule to form the putative intermediate (18)ON-O-CO2(-)/(-)O2C-(18)O-NO. The by far largest fraction of this intermediate decomposes back to (18)ON-O(-)/(-18)O-NO and CO2. A very small fraction of the intermediate, however, rearranges and finally decomposes to form (18)OCO and nitrite. This reaction is slower in the presence of an isolated erythrocytic CA isoform II. In summary, NO2(-), CO2 and CA are ubiquitous. The chemical reaction of NO2(-) with CO2 and its modulation by CA isoforms may play important roles in the transport of

  13. Variation of δ18O and δD in precipitation and stream waters across the Kashmir Himalaya (India) to distinguish and estimate the seasonal sources of stream flow

    Science.gov (United States)

    Jeelani, Gh.; Saravana Kumar, U.; Kumar, Bhishm

    2013-02-01

    SummaryThe spatial and temporal distribution of δ18O and δD measurements of precipitation and stream waters were used to distinguish various sources and components of stream flow and to estimate their residence times in snow dominated mountainous catchments of Kashmir Himalaya. A marked spatial and seasonal variability of stable isotopes of oxygen and hydrogen was observed in precipitation with δ18O and δD varied from -12.98‰ to -0.58‰ and -74.5‰ to -11.1‰, respectively during the period from November 2007 to January 2009. The seasonal changes in stable isotopes of precipitation with depleted and enriched 18O and 2H in January/March/May and July/September/November, respectively at each site are attributed to the seasonal changes in ambient temperature, precipitation, source of moisture and airmass trajectory. The mean altitude effect of -0.23‰ and -1.2‰ per 100 m change in elevation for δ18O and δD, respectively, was observed based on amount weighted mean precipitation isotopic composition data. Unlike precipitation, less variability of stable isotopes of streams was found with δ18O and δD ranging from -11.56‰ to -6.26‰ and -65.4‰ to -36.4‰, respectively, the depleted values being observed in the headwaters of the streams/tributaries and enriched values at lower elevations of the watersheds. The LMWL established for the Kashmir Himalayas, based on amount weighted monthly samples is δD = 7.59 (± 0.32) × δ18O + 11.79 (± 2.07) (r2 = 0.96) with lower slope and intercept than GMWL, is very close to the LMWL for the western Himalayas. The seasonal regression lines suggest the effect of evaporation with lower slopes and intercepts except in winter. The results suggest that the winter precipitation (snow) dominantly contributes the annual stream flow with average snowmelt contribution of about 29% in early spring, 66% in late spring, 61% in summer while the baseflow contribution is found in the order of 40% in autumn season. The mean stream

  14. A dynamic soil chamber system coupled with a tunable diode laser for online measurements of delta-13C, delta-18O, and efflux rate of soil respired CO2

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Heath H [Los Alamos National Laboratory; Mcdowell, Nate [Los Alamos National Laboratory; Hanson, David [UNM; Hunt, John [LANDCARE RESEARCH

    2009-01-01

    High frequency observations of the stable isotopic composition of CO(2) effluxes from soil have been sparse due in part to measurement challenges. We have developed an open-system method that utilizes a flow-through chamber coupled to a tunable diode laser (TDL) to quantify the rate of soil CO(2) efflux and its delta(13)C and delta(18)O values (delta(13)C(R) and delta(18)O(R), respectively). We tested the method first in the laboratory using an artificial soil test column and then in a semi-arid woodland. We found that the CO(2) efflux rates of 1.2 to 7.3 micromol m(-2) s(-1) measured by the chamber-TDL system were similar to measurements made using the chamber and an infrared gas analyzer (IRGA) (R(2) = 0.99) and compared well with efflux rates generated from the soil test column (R(2) = 0.94). Measured delta(13)C and delta(18)O values of CO(2) efflux using the chamber-TDL system at 2 min intervals were not significantly different from source air values across all efflux rates after accounting for diffusive enrichment. Field measurements during drought demonstrated a strong dependency of CO(2) efflux and isotopic composition on soil water content. Addition of water to the soil beneath the chamber resulted in average changes of +6.9 micromol m(-2) s(-1), -5.0 per thousand, and -55.0 per thousand for soil CO(2) efflux, delta(13)C(R) and delta(18)O(R), respectively. All three variables initiated responses within 2 min of water addition, with peak responses observed within 10 min for isotopes and 20 min for efflux. The observed delta(18)O(R) was more enriched than predicted from temperature-dependent H(2)O-CO(2) equilibration theory, similar to other recent observations of delta(18)O(R) from dry soils (Wingate L, Seibt U, Maseyk K, Ogee J, Almeida P, Yakir D, Pereira JS, Mencuccini M. Global Change Biol. 2008; 14: 2178). The soil chamber coupled with the TDL was found to be an effective method for capturing soil CO(2) efflux and its stable isotope composition at high

  15. Discerning the interactions between environmental parameters reflected in δ13C and δ18O of recent fluvial tufas: Lessons from a Mediterranean climate region

    Science.gov (United States)

    Osácar, M. Cinta; Arenas, Concha; Auqué, Luis; Sancho, Carlos; Pardo, Gonzalo; Vázquez-Urbez, Marta

    2016-11-01

    δ13C and δ18O of recent, continuous tufa records, obtained during a monitoring period spanning 3 to 13 years, are compared with the corresponding, known environmental conditions. Three rivers in NE Iberia (located along a 200-km N-S transect) are used for this comparison. The isotopic variations through space and time are discussed in terms of the environmental and geological parameters that operate on different scales, focusing on discerning the interactions between these parameters and providing examples of possible misinterpretation of climatic conditions, which is important to past climate studies based on isotopic data. The calculation of the actual isotopic fractionation coefficients, and the comparison with the literature-derived coefficients, demonstrates that the studied tufa formation was close to isotopic equilibrium to reflect the water temperature. The difference between mean measured water temperature (Tw) and mean calculated Tw (based on δ18Ocalcite and measured δ18Owater) is less than 2.7 °C. Tendencies of these calculated Tw are similar to the regional air temperature (Tair) tendencies through time, in particular in the case of the 13-year record, although certain deviations exist over shorter time spans. The best agreement between measured and calculated Tw and between δ18Ocalcite-based Tw tendencies and Tair tendencies corresponds to the tufa stromatolite facies. Differences between the δ18Ocalcite records of the three rivers cannot be attributed to temperature changes, but to the varying influences of groundwater inputs and isotopic rainfall composition in each river. Without considering these parameters, δ18Ocalcite-based Tw calculations yield inaccurate results when comparing the study sites. δ13Ccalcite values do not exhibit distinct patterns over time, and δ13Ccalcite variations are likely caused by local processes that do not reflect general environmental changes. These findings underscore the significance of accounting for both

  16. Stable isotopes (δ 18O and δ 13C), trace and minor element compositions of Recent scleractinians and Last Glacial bivalves at the Santa Maria di Leuca deep-water coral province, Ionian Sea

    Science.gov (United States)

    Correa, Matthias López; Montagna, Paolo; Vendrell-Simón, Begoña; McCulloch, Malcolm; Taviani, Marco

    2010-03-01

    The aragonitic skeletons of bathyal cold-water corals have a high potential as geochemical in situ archives for paleoceanography. Oxygen isotopes and stable carbon isotopes (δ 18O and δ 13C) have been analyzed, as well as trace and minor element compositions (e.g. Mg/Ca, Sr/Ca, U/Ca, B/Ca and P/Ca) in Lophelia pertusa, one of the most important frame-builders at the Santa Maria di Leuca (SML) deep-water coral hotspot in the Central Mediterranean. The Apulian Bank is swept by strong currents of the Adriatic Deep Water Outflow. The temperature of 13.9 °C is the highest temperature recorded for L. pertusa and provides an important end-member of environmental conditions for geochemical analyses on living Atlantic and Mediterranean cold-water corals. Temperature and salinity (38.77 PSU) are stable throughout the year, and thus virtually no changes should be observed in the stable oxygen isotope signal—if the coral precipitates its skeleton in equilibrium with seawater. We measured various marine properties, such as the seawater oxygen isotope composition (δ 18O sw), stable carbon isotope composition (δ 13C DIC) of dissolved inorganic carbon (DIC), and dissolved inorganic nutrient concentrations (PO 4, NO 3, NO 2, NH 3 and SiO 2). Bottom water at the coral sites shows a mean oxygen isotope composition of 1.47‰ δ 18O sw-VSMOW, and δ 13C DIC showed a mean of 1.1‰ VPDB. A section of a living L. pertusa with a thick theca calcification was probed with a Merchantek MicroMill at a high spatial sampling resolution with 10 samples per 1 mm. This reduced the signal-smoothing inherent to conventional sampling. The δ 18O ag of coral aragonite ranges between -2.0‰ and +2.8‰ VPDB and the δ 13C ag ranges between -7.77‰ and +1.47‰ VPDB. The Gaussian data distribution for both parameters, including heavy equilibrium values, suggests the completeness of the captured isotopic variability. The strict linear correlation of δ 13C and δ 18O displays a strong 'kinetic

  17. Radiogenic and stable isotopes of mid-Miocene silicic volcanism in eastern Oregon: Evidence for variable and high Sr / low δ18O domains west of the terrane-cratonic lithosphere transition

    Science.gov (United States)

    Jenkins, E. N.; Streck, M. J.; Ramos, F. C.; Bindeman, I. N.

    2013-12-01

    Widespread mid-Miocene rhyolite volcanism of eastern Oregon mostly coeval with flood basalts of the Columbia River Basalt Province allows for mapping crustal domains using radiogenic and stable isotopes. Rhyolites are thought to be derived in large part by partial melting of the crust and thus yield direct information on the composition of the crust. Silicic volcanism is expressed in the form of numerous domes and tuffs exposed over a wide area (~300 km in N-S dimension and ~100 km in E-W dimension) west of the craton boundary, which runs parallel but mostly east of the Oregon-Idaho state border as delineated by geophysical characteristics and isotopic transitions. Here, we mainly focus on initial 87Sr/86Sr ratios and δ18O obtained from mid-Miocene silicic volcanic centers in eastern Oregon. Our data, in combination with data from the literature, indicate variable 87Sr/86Sr mostly along longitudinal sections, yet more similar ratios in latitudinal directions. Except for rare examples on the west side, dispersion of 87Sr/86Sr ratios among both silicic and basaltic rocks occurs eastward of 118.6°W. For example, rhyolites in the Owyhee region between 117.10°W and 117.25°W retain 87Sr/86Sr ratios ranging from 0.70413 to 0.70566. The most radiogenic Sri ratio of 0.70787 in our study is obtained on a plagioclase separate from Buchanan Dome complex located near the western boundary of our study area. Feldspar separates and fresh groundmass of samples from adjacent centers yield similar 87Sr/86Sr ratios. δ18O values for feldspars range from below 2‰ to above 9‰. In addition, there is a crude trend of rhyolites having lower δ18O and more radiogenic 87Sr/86Sr ratios. With one exception, all samples with 87Sr/86Sr above 0.7050 are depleted in 18O18O 6‰). The most depleted oxygen ratios (<2‰) come from rhyolites ~80 km west of the cratonic margin reflecting remelting or assimilation of hydrothermally altered crust. Yet, some compositionally similar rhyolites

  18. Positron annihilation characterization of free volume in micro- and macro-modified Cu0.4Co0.4Ni0.4Mn1.8O4 ceramics

    Science.gov (United States)

    Klym, H.; Ingram, A.; Shpotyuk, O.; Hadzaman, I.; Solntsev, V.; Hotra, O.; Popov, A. I.

    2016-07-01

    Free volume and pore size distribution size in functional micro and macro-micro-modified Cu0.4Co0.4Ni0.4Mn1.8O4 ceramics are characterized by positron annihilation lifetime spectroscopy in comparison with Hg-porosimetry and scanning electron microscopy technique. Positron annihilation results are interpreted in terms of model implication positron trapping and ortho-positronium decaying. It is shown that free volume of positron traps are the same type for macro and micro modified Cu0.4Co0.4Ni0.4Mn1.8O4 ceramics. Classic Tao-Eldrup model in spherical approximation is used to calculation of the size of nanopores smaller than 2 nm using the ortho-positronium lifetime.

  19. Dielectric, magnetic and electrical properties of Bi0.5Na0.5TiO3 - CoMn0.2Fe1.8O4 composites

    Science.gov (United States)

    Kumar, Yogesh; Yadav, K. L.

    2016-05-01

    The magnetoelectric composites of inverse spinel ferrite CoMn0.2Fe1.8O4 (CMFO) and Bi0.5Na0.5TiO3 (BNT) with general formula (x) Bi0.5Na0.5TiO3 - (1-x) CoMn0.2Fe1.8O4 have been prepared through hybrid processing route. X-ray diffraction pattern reveal that CFMO crystallizes in inverse cubic spinel phase and BNT in rhombohedral perovskite phase. Dielectric constant and dielectric loss were reported with frequency at room temperature. The magnetic properties of the composites were calculated from the Magnetization - Magnetic field (M-H) hysteresis loops obtained at room temperature. Ferroelectric properties of the composites were also investigated using Polarization -Electric field (P-E) hysteresis loops.

  20. Water-Isotopes (2H, 3H, 18O) to trace the source and timing of recharge in a fractured granite aquifer in Western Kenya, Africa

    Science.gov (United States)

    Kralik, Martin; Whylidal, Stefan; Asunah, Francis; Sültenfuß, Jürgen

    2014-05-01

    The Vihiga District in West Kenya North-West of Lake Victoria is one of the most densely populated areas in Kenya with 1033 person per square kilometer. To find the most suitable location of an own well for a Primary School in this district, springs, school wells and creeks were sampled in the surroundings to get information about the hydrological cycle in the area. The Waluka Primary school (0.02134°N, 34.64311°E) is situated on the northern slope of the Maragoli Hills 20 km to the North-West of the Nyanzan provincial capital of Kisumu at the eastern shore of Lake Victoria. The hilly relief varies between 1535 - 1675m. The yearly precipitation is between 1200-1600 mm/a (23°C mean temperature) with biannual rainy seasons in which the long rains are generally from March to May as the Inter-Tropical Convergence Zone (ITCZ) moves northwards, and the short rains are typically from October to December as the ITCZ retreats southwards. A lateritic soil covers a thin alteration zone above the Precambrian Maragoli-Granite (Saggerson, 1952). Water circulates either in the thin alteration zone or in fault zones cutting through the Precambrian granite. From discharge measurements of two springs and a creek at the end of the dry season (February 2012) a minimum discharge of ca. 10-20 L/s km2 (300-600 mm) can be estimated. The water is of the alkaline sulfate-nitrate type with low mineralization (70-150 μ S/cm, 25°C) and a low pH of about 5 to 6. The delta oxygen-18 and deuterium value ranges between -2.84 to -1.98 oand -8.5 to - 3.9 o(VSMOW). The deuterium excess ranges from 11.7-14.2 oThe water of one spring and well close to the school have a tritium content of 1.42 - 1.62 TU. All groundwater has a low arsenium, fluorine and uranium content, which had only a short soil passage. The relatively elevated, but not problematic content in nitrate (10 - 16 mg/L) probaly reflects the intensive agricultural activities in this area. As the mean δ 18O values during the rainy

  1. Processes affecting δ34S and δ18O values of dissolved sulfate in alluvium along the Canadian River, central Oklahoma, USA

    Science.gov (United States)

    Tuttle, Michele L.W.; Breit, George N.; Cozzarelli, Isabelle M.

    2009-01-01

    The δ34S and δ18O values for dissolved sulfate in groundwater are commonly used in aquifer studies to identify sulfate reservoirs and describe biogeochemical processes. The utility of these data, however, often is compromised by mixing of sulfate sources within reservoirs and isotope fractionation during sulfur redox cycling. Our study shows that, after all potential sulfate sources are identified and isotopically characterized, the δ34SSO4 and δ18OSO4 values differentiate processes such as sulfate-source mixing, sulfide oxidation, barite dissolution, and organosulfur decomposition. During bacterial reduction of sulfate, the values reflect kinetic sulfur isotope fractionation and exchange of oxygen isotopes between sulfate and water. Detailed analysis of the chemistry (Cl and SO4 concentrations) and isotopic composition (δ2HH2Oand δ18OH2O) of groundwater in an alluvial aquifer in Central Oklahoma, USA allowed the identification of five distinct end members that supply water to the aquifer (regional groundwater flowing into the study area, river water, leachate from a closed landfill that operated within the site, rain, and surface runoff). The δ34SSO4 and δ18OSO4 values in each end member differentiated three sources of sulfate: sulfate dissolved from Early to Late Permian rocks within the drainage basin (δ34SSO4 = 8–12‰ and δ18OSO4 = 10‰), iron sulfides oxidized by molecular oxygen during low water-table levels (δ34SSO4 = − 16‰ and δ18OSO4 = 10‰), and organosulfur compounds (predominately ester sulfates) from decomposition of vegetation on the surface and from landfill trash buried in the alluvium (δ34SSO4 = 8‰ and δ18OSO4 = 6‰). During bacterial reduction of these sulfate sources, similar isotope fractionation processes are recorded in the parallel trends of increasing δ34SSO4 and δ18OSO4 values. When extensive reduction occurs, the kinetic sulfur isotope fractionation (estimated by εH2S–SO4 = − 23

  2. 减压精馏分离稳定同位素18O的模拟优化研究%Simulation and Optimization of Stable Isotope 18O Separation by Water Vacuum Distillation

    Institute of Scientific and Technical Information of China (English)

    陈玉岩; 秦川江; 肖斌; 徐静安

    2012-01-01

    研究建立了1座采用蒸馏水减压精馏分离稳定同位素18O的实验装置,其填料层高20 m,塔径为0.1m,塔内装填自主开发的PAC-18O专用填料.首先利用Aspen Plus建立模型并验证其可靠性,然后利用此模型得出1组模拟数据,并利用人工神经网络(ANN)及Statistica软件对这组模拟数据进行优化设计.综合分析了塔顶压力及产品采出量对18O产品丰度的影响.结果表明,产品18O的丰度随塔顶压力和产品采出量的降低而升高,并得出最优化的塔压及18O丰度与产品采出量间的数学关联式.本研究采用的模拟优化方法可应用到18O的产业化设计及推广至传统精馏过程的优化设计中.%In the research, a stable isotope 18O separation column was set up by water vacuum distillation with 20 m packing height and 0. 1 m diameter of the column. The self-developed special packing named PAC-18O was packed inside the column. Firstly, a model was created by using the Aspen Plus software, and then the simulation results were validated by test results. Secondly, a group of simulation results were created by Aspen Plus, and the optimal operation conditions were gotten by using the artificial neural network (ANN) and Statistica software. Considering comprehensive factors drawn from column pressure and from withdrawing velocity, conclusions were reached on the study of the impact on the abundance of the isotope I8O. The final results show that the abundance of the isotope 18O increases as column pressure dropping and withdrawing velocity decreasing. Besides, the optimal column pressure and the incidence formula between the abundance of the isotope 18O and withdrawing velocity were gotten. The conclusion is that the method of simulation and optimization can be applied to 18O industrial design and will be popular in traditional distillation process to realize optimization design.

  3. Evidence from sup 18 O exchange measurements for steps involving a weak acid and a slow chemical transformation in the mechanism of phosphorylation of the gastric H sup + ,K sup + -ATPase by inorganic phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Faller, L.D.; Diaz, R.A. (Univ. of California School of Medicine and Veterans Administration Hospital Center, Los Angeles (USA))

    1989-08-22

    Phosphorylation of the gastric H,K-ATPase by P{sub i} has been studied by measuring the P{sup 18}O{sub j}{sup 16}O{sub 4-j} distribution as a function of time at different H{sup +}, K{sup +}, and ({sup 18}O)P{sub i} concentrations. The advantage of isotope exchange measurements is that the P{sup 18}O{sub j}{sup 16}O{sub 4-j} distribution depends on the relative rates of HOH loss to form the phosphoenzyme intermediate and P{sub i} dissociation from the enzyme. Therefore, {sup 18}O exchange is a sensitive probe of mechanism. K{sup +} increases the exchange rate ({nu}{sub ex}) but does not affect the partition coefficient (P{sub c}) that determines the P{sup 18}O{sub j}{sup 16}O{sub 4-j} distribution. Conversely, H{sup +} inhibits exchange. A single P{sub c} describes the data at every pH, but the value increases from 0.04 to pH 8 to 0.64 at pH 5.5. {nu}{sub ex} depends hyperbolically on (P{sub i}){sub 0}. K{sub m} for P{sub i} does not depend on pH, and P{sub c} does not depend on (P{sub i}){sub 0}. Individual rate constants in the phosphorylation mechanism are estimated. Formation of the E{center dot}P{sub i} complex that looses HOH is 1-2 orders of magnitude slower at pH 5.5 than at pH 8 and is not diffusion controlled. The observed change in P{sub c} with pH is compatible with catalysis occurring by a different mechanism when a group with pK{sub a} = 7.2 is protonated. Slower than diffusion-controlled formation of the E{center dot}P{sub i} complex that splits out HOH is evidence for a relatively slow, unimolecular chemical transformation involving an additional intermediate in the phosphorylation mechanism, such as a protein conformational change.

  4. Complete Measurement of Stable Isotopes in N2O (δ15N, δ15Nα, δ15Nβ, δ18O, δ17O) Using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS)

    Science.gov (United States)

    Leen, J. B.; Gupta, M.

    2014-12-01

    Nitrate contamination in water is a worldwide environmental problem and source apportionment is critical to managing nitrate pollution. Fractionation caused by physical, chemical and biological processes alters the isotope ratios of nitrates (15N/14N, 18O/16O and 17O/16O) and biochemical nitrification and denitrification impart different intramolecular site preference (15N14NO vs. 14N15NO). Additionally, atmospheric nitrate is anomalously enriched in 17O compared to other nitrate sources. The anomaly (Δ17O) is conserved during fractionation processes, providing a tracer of atmospheric nitrate. All of these effects can be used to apportion nitrate in soil. Current technology for measuring nitrate isotopes is complicated and costly - it involves conversion of nitrate to nitrous oxide (N2O), purification, preconcentration and measurement by isotope ratio mass spectrometer (IRMS). Site specific measurements require a custom IRMS. There is a pressing need to make this measurement simpler and more accessible. Los Gatos Research has developed a next generation mid-infrared Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) analyzer to quantify all stable isotope ratios of N2O (δ15N, δ15Nα, δ15Nβ, δ18O, δ17O). We present the latest performance data demonstrating the precision and accuracy of the OA-ICOS based measurement. At an N2O concentration of 322 ppb, the analyzer quantifies [N2O], δ15N, δ15Na, δ15Nb, and δ18O with a precision of ±0.05 ppb, ±0.4 ‰, ±0.45 ‰, and ±0.6 ‰, and ±0.8 ‰ respectively (1σ, 100s; 1σ, 1000s for δ18O). Measurements of gas standards demonstrate accuracy better than ±1 ‰ for isotope ratios over a wide dynamic range (200 - 100,000 ppb). The measurement of δ17O requires a higher concentration (1 - 50 ppm), easily obtainable through conversion of nitrates in water. For 10 ppm of N2O, the instrument achieves a δ17O precision of ±0.05 ‰ (1σ, 1000s). This performance is sufficient to quantify atmospheric

  5. Comparisons on seasonal and annual variations of δ18O in precipitation%不同时间尺度下降水中氧稳定同位素的时空变化

    Institute of Scientific and Technical Information of China (English)

    章新平; 姚檀栋

    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 1960s to the

  6. Isotope tracing ({sup 29}Si and {sup 18}O) of the alteration mechanisms of the French glass 'SON68' used for the storage of nuclear waste; Tracage isotopique ({sup 29}Si and {sup 18}O) des mecanismes de l'alteration du verre de confinement des dechets nucleaires: 'SON68'

    Energy Technology Data Exchange (ETDEWEB)

    Valle, N

    2001-07-01

    This study aims to enhance our understanding of the mechanisms of aqueous corrosion of the glasses used for the storage of nuclear waste. Glass samples 'SON68', doped with a different rare earth element (La, Ce or Nd), were altered simultaneously with water enriched in {sup 29}Si and {sup 18}O, throughout a period of 20 months. The aim of such isotope tracing was (i) to follow the 'real' exchanges between glass and solution and (ii) to understand the reactions involving Si-O bonds in the leached layer during alteration. Leachates were analyzed by ICP-MS and -AES, and elemental and isotopic variations in the altered glass layer were measured by ion-probe, using a depth profiling technique. Elemental analyses enabled the distribution of the elements in the two layers of altered glass (phyllosilicates and gel) to be established, and the results reveal a selective partitioning of elements between the two layers. Isotopic analyses of altered layers and leachates allowed phyllosilicates to be distinguished from gel, and suggest two different mechanisms of formation. Whilst phyllosilicates grow on the surface of the glass by a mechanism of precipitation, gel is formed by a succession of hydrolysis / condensation reactions taking place mainly at the gel / pristine glass interface. This gel is formed by the in situ rearrangement of hydrated species, without reaching equilibrium with the solution. Moreover, an experimental technique has been developed enabling one to trace the transport of silicon from the solution into the altered glasses, under an isotopic gradient. Diffusion profiles, obtained by ion-probe, have been modeled and have allowed the determination of the apparent silicon diffusion coefficient (DSi) in gels. Therefore, our experiments have permitted the quantification of the influence of both the alteration conditions (dynamic or static tests) and the solution composition on the value of DSi. (author)

  7. H6P2W18O62/MCM-41催化剂的制备、表征及其催化合成乙酰水杨酸%Preparation and Characterization of H6P2W18O62/MCM-41 Catalyst for Acetylsalicylic Acid Synthesis

    Institute of Scientific and Technical Information of China (English)

    曹小华; 王原平; 雷艳虹; 徐常龙; 占昌朝

    2014-01-01

    采用浸渍法将Dawson结构的磷钨酸H6P2W 18O62(简写为P2W18)负载在MCM-41分子筛上,制备出新型P2W18/MCM-41催化剂;采用FTIR,XRD,SEM,EDS等方法对催化剂进行了表征.表征结果显示,P2W18/MCM-41催化剂既保持了MCM-41分子筛的孔道结构,又保持了P2W18的Dawson结构.同时研究了P2W18/MCM-41催化剂对乙酰水杨酸合成反应的活性,通过正交实验确定了优化工艺条件:n(水杨酸)∶n(乙酸酐)=1.0∶1.5、P2W18/MCM-41催化剂用量2.7%(基于反应物的质量)、反应温度80℃、反应时间10 min.在此优化条件下,乙酰水杨酸收率为88.1%.P2W18/MCM-41催化剂重复使用5次,乙酰水杨酸收率仍可达76.7%.

  8. Multivariate analysis of calcareous nanno fossils and stable isotopic ({delta}{sup 18}O and {delta}{sup 13}C) in the upper Campanian - lower Maastrichtian of the Campos Basin, Brazil; Analise multivariada em nanofosseis calcarios e isotopos estaveis ({delta}{sup 18}O e {delta}{sup 13}C) do Campaniano superior - Maastrichtiano inferior na Bacia de Campos

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Luiz Carlos Veiga de [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas. Gerencia de Bioestratigrafia e Paleoecologia]. E-mail: lcveiga@petrobras.com.br; Rodrigues, Rene; Lemos, Valesca Brasil

    2005-05-01

    Qualitative analysis in calcareous nanno fossils is a powerful tool for bio stratigraphic uses, principally in identification of bio zones and determination of relative age. But quantitative studies must be applied for pale oceanographic applications and high resolution bio stratigraphy. In order to better understand the relationships between the different species of nanno fossils, new methodologies and non-traditional correlation tools were tested on a 18 m upper Campanian - lower Maastrichtian core from Campos Basin. Multiple regression helped to determine the best counting method. Watznaueria barnesae and Micula decussata dominate the fossil assemblage and have inverse abundances to each other. Both were opportunist species in competition for nutrients. Q mode factorial analysis (57 samples, 19 variables) was applied to the same core and shows that two factors explain 99.2% of the total variance of the micro fossil assemblage. The first factor represents 83.6% and the second factor only 15.6% of the total variance. The former is associated with Watznaueria barnesae, Cribrosphaerella ehrenbergii and Stradneria crenulata, which represent the original population of nano plankton. The latter factor is associated with Micula decussata, which is believed to represent the effect of solution at the sediment water interface. Both factors were used to develop a dissolution-sea level curve for nanno fossils. When combined with oxygen and carbon isotopes, this curve clearly shows that higher dissolution occurred during the late Campanian - early Maastrichtian time when {delta}{sup 18}O, {delta}{sup 13} C and TOC all had lower values. These correlations indicate a strong link between high sea levels, high temperatures and lower amount of continental organic debris. (author)

  9. A 500 year seasonally resolved δ18O and δ13C, layer thickness and calcite fabric record from a speleothem deposited in equilibrium of the Han-sur-Lesse cave, Belgium

    Directory of Open Access Journals (Sweden)

    M. Van Rampelbergh

    2014-10-01

    Full Text Available Speleothem δ18O and δ13C signals have already proven to enable climate reconstructions at high resolution. However, seasonally resolved speleothem records are still scarce and often difficult to interpret in terms of climate due to the multitude of factors that can affect the proxy signals. In this paper, a fast growing (up to 2 mm yr−1 seasonally laminated speleothem from the Han-sur-Lesse cave (Belgium is analyzed for its δ18O and δ13C values, layer thickness and changes in calcite fabric. The studied part of the speleothem covers the most recent 500 years as indicated by layer counting and confirmed by 20 U/Th-ages. Epikarst recharge occurs mainly in winter and lesser during spring and fall. a good correlation can be established between lower winter temperatures and lower winter precipitation (DJF based on the measured data by the Belgian meteorological institute since 1833 indicating that a dry winter is also a cold winter. Colder and dryer winters cause lower winter recharge and generally drier conditions in the cave. Lower winter recharge decreases the amount of isotopically light (δ18O winter precipitation added to the epikarst in comparison to the heavier spring and fall waters, which leads to a net increase in δ18O value of the water in the epikarst. Increased δ18O values in the Proserpine are consequently interpreted to reflect colder and dryer winters. Higher δ13C signals are interpreted to reflect increased prior calcite precipitation (PCP due to colder and dryer winters, when recharge is lower. Thinner layers and darker calcite relate to slower growth and occur when drip rates are low and when the drip water calcium ion concentration is low due to increased PCP, both caused by lower recharge during periods with colder and dryer winters. Exceptionally cold and dry winters cause the drip discharge to decrease under a certain threshold value inducing anomalies in the measured proxy records. Such anomalies occur from 1565 to

  10. Life history of the individuals buried in the St. Benedict Cemetery (Prague, 15th-18th centuries): insights from (14)C dating and stable isotope (δ(13)C, δ(15)N, δ(18)O) analysis.

    Science.gov (United States)

    Salesse, Kevin; Dufour, Élise; Castex, Dominique; Velemínský, Petr; Santos, Frédéric; Kuchařová, Hedvika; Jun, Libor; Brůžek, Jaroslav

    2013-06-01

    Funerary practices and bioarchaeological (sex and age) data suggest that a mortality crisis linked to an epidemic episode occurred during the fifth phase of the St. Benedict cemetery in Prague (Czech Republic). To identify this mass mortality episode, we reconstructed individual life histories (dietary and mobility factors), assessed the population's biological homogeneity, and proposed a new chronology through stable isotope analysis (δ(13)C, δ(18)O and δ(15)N) and direct radiocarbon dating. Stable isotope analysis was conducted on the bone and tooth enamel (collagen and carbonate) of 19 individuals from three multiple graves (MG) and 12 individuals from individual graves (IG). The δ(15)N values of collagen and the difference between the δ(13)C values of collagen and bone carbonate could indicate that the IG individuals had a richer protein diet than the MG individuals or different food resources. The human bone and enamel carbonate and δ(18)O values suggest that the majority of individuals from MG and all individuals from IG spent most of their lives outside of the Bohemian region. Variations in δ(18)O values also indicate that all individuals experienced residential mobility during their lives. The stable isotope results, biological (age and sex) data and eight (14)C dates clearly differentiate the MG and IG groups. The present work provides evidence for the reuse of the St. Benedict cemetery to bury soldiers despite the funeral protest ban (1635 AD). The Siege of Prague (1742 AD) by French-Bavarian-Saxon armies is identified as the cause of the St. Benedict mass mortality event.

  11. Monte Carlo simulation and radiometric characterization of proton irradiated [{sup 18}O]H{sub 2}O for the treatment of the waste streams originated from [{sup 18}F]FDG synthesis process

    Energy Technology Data Exchange (ETDEWEB)

    Remetti, Romolo, E-mail: romolo.remetti@uniroma1.i [' Sapienza' University of Rome, Department of Energetics, via A.Scarpa 14, 00161 Rome (Italy); Burgio, Nunzio T. [ENEA, Casaccia Research Centre, Via Anguillarese, 301, 00060 S. Maria Di Galeria, Rome (Italy); Maciocco, Luca; Arcese, Manuele; Filannino, M. Azzurra [Advanced Accelerator Applications (AAA), 20 rue du Diesel, 01630, Saint-Genis Pouilly (France)

    2011-07-15

    The aim of this work is quantifying the radionuclidic impurities of the irradiated [{sup 18}O]water originated by the [{sup 18}F]FDG synthesis process, and characterizing, from a radioprotection point of view, the waste streams produced. Two samples o