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Sample records for rhenium-osmium isotope systematics

  1. Methods for the separation of rhenium, osmium and molybdenum applicable to isotope geochemistry

    Science.gov (United States)

    Morgan, J.W.; Golightly, D.W.; Dorrzapf, A.F.

    1991-01-01

    Effective methods are described for the chemical separation of rhenium, osmium and molybdenum. The methods are based on distillation and anion-exchange chromatography, and have been the basis for rhenium-osmium isotope studies of ore deposits and meteorites. Successful anion-exchange separation of osmium requires both recognition and careful control of the osmium species in solution; thus, distillation of osmium tetroxide from a mixture of sulfuric acid and hydrogen peroxide is preferred to anion-exchange. Distribution coefficients measured for perrhenate in sulfuric acid media are sufficiently high (Kd > 500) for rhenium to be directly loaded onto an ion-exchange column from a distillation residue and subsequently eluted with nitric acid. Polymerization of molybdenum species during elution is prevented by use of a solution that is 1M in hydrochloric acid and 1M in sodium chloride. ?? 1991.

  2. Rhenium-osmium isotopes and highly siderophile elements in ultramafic rocks from the Eoarchean Saglek Block, northern Labrador, Canada: implications for Archean mantle evolution

    Science.gov (United States)

    Ishikawa, Akira; Suzuki, Katsuhiko; Collerson, Kenneth D.; Liu, Jingao; Pearson, D. Graham; Komiya, Tsuyoshi

    2017-11-01

    We determined highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, and Re) concentrations and 187Os/188Os ratios for ultramafic rocks distributed over the Eoarchean gneiss complex of the Saglek-Hebron area in northern Labrador, Canada in order to constrain to what extent variations in HSE abundances are recorded in Early Archean mantle that have well-resolved 182W isotope anomalies relative to the present-day mantle (∼+11 ppm: Liu et al., 2016). The samples analysed here have been previously classified into two suites: mantle-derived peridotites occurring as tectonically-emplaced slivers of lithospheric mantle, and metakomatiites comprising mostly pyroxenitic layers in supracrustal units dominated by amphibolites. Although previous Sm-Nd and Pb-Pb isotope studies provided whole-rock isochrons indicative of ∼3.8 Ga protolith formation for both suites, our whole-rock Re-Os isotope data on a similar set of samples yield considerably younger errorchrons with ages of 3612 ± 130 Ma (MSWD = 40) and 3096 ± 170 Ma (MSWD = 10.2) for the metakomatiite and lithospheric mantle suites, respectively. The respective initial 187Os/188Os = 0.10200 ± 18 for metakomatiites and 0.1041 ± 18 for lithospheric mantle rocks are within the range of chondrites. Re-depletion Os model ages for unradiogenic samples from the two suites are consistent with the respective Re-Os errorchrons (metakomatiite TRD = 3.4-3.6 Ga; lithospheric mantle TRD = 2.8-3.3 Ga). These observations suggest that the two ultramafic suites are not coeval. However, the estimated mantle sources for the two ultramafics suites are similar in terms of their broadly chondritic evolution of 187Os/188Os and their relative HSE patterns. In detail, both mantle sources show a small excess of Ru/Ir similar to that in modern primitive mantle, but a ∼20% deficit in absolute HSE abundances relative to that in modern primitive mantle (metakomatiite 74 ± 18% of PUM; lithospheric mantle 82 ± 10% of PUM), consistent with the

  3. Rhenium-osmium evidence for regional mineralization in southwestern north america.

    Science.gov (United States)

    McCandless, T E; Ruiz, J

    1993-09-03

    More than 40 base metal porphyry ore deposits in southwestern North America are associated with the Laramide orogeny (about 90 million to 50 million years ago). Rhenium-osmium dates on molybdenite, a rhenium-enriched sulfide common in many of the deposits, reveal that in individual deposits mineralization occurs near the final stages of magmatic activity irrespective of the time of inception, magnitude, or duration of magmatism. Deposits that differ widely in location and in the extent and timing of magmatism have nearly identical ages for mineralization. Rhenium-osmium-ages suggest that mineralization occurred during two distinct intervals from about 74 million to 70 million years ago and from 60 million to 55 million years ago. Most deposits that formed in the oldest interval are within the older Precambrian basement of northwestern Arizona, whereas the younger deposits are restricted to the younger Precambrian basement in southern Arizona and northern Mexico. Synchronous, widespread mineralization indicates that similar crust-mantle interaction occurred on a regional scale for ore deposits once thought to be the product of localized processes.

  4. Physical Foundations of Rhenium-Osmium Method - A Review

    National Research Council Canada - National Science Library

    Dąbek, Józef; Halas, Stanislaw

    2007-01-01

    A newly acquired mass spectrometer MI 1201 by the Mass Spectrometry Laboratory will be adapted to determine rhenium and osmium isotope concentrations using negative thermal ionization mass spectrometry (NTIMS...

  5. Evaluation of the rhenium-osmium geochronometer in the Phosphoria petroleum system, Bighorn Basin of Wyoming and Montana, USA

    Science.gov (United States)

    Lillis, Paul G.; Selby, David

    2013-01-01

    Rhenium-osmium (Re-Os) geochronometry is applied to crude oils derived from the Permian Phosphoria Formation of the Bighorn Basin in Wyoming and Montana to determine whether the radiogenic age reflects the timing of petroleum generation, timing of migration, age of the source rock, or the timing of thermochemical sulfate reduction (TSR). The oils selected for this study are interpreted to be derived from the Meade Peak Phosphatic Shale and Retort Phosphatic Shale Members of the Phosphoria Formation based on oil-oil and oil-source rock correlations utilizing bulk properties, elemental composition, δ13C and δ34S values, and biomarker distributions. The δ34S values of the oils range from -6.2‰ to +5.7‰, with oils heavier than -2‰ interpreted to be indicative of TSR. The Re and Os isotope data of the Phosphoria oils plot in two general trends: (1) the main trend (n = 15 oils) yielding a Triassic age (239 ± 43 Ma) with an initial 187Os/188Os value of 0.85 ± 0.42 and a mean square weighted deviation (MSWD) of 1596, and (2) the Torchlight trend (n = 4 oils) yielding a Miocene age (9.24 ± 0.39 Ma) with an initial 187Os/188Os value of 1.88 ± 0.01 and a MSWD of 0.05. The scatter (high MSWD) in the main-trend regression is due, in part, to TSR in reservoirs along the eastern margin of the basin. Excluding oils that have experienced TSR, the regression is significantly improved, yielding an age of 211 ± 21 Ma with a MSWD of 148. This revised age is consistent with some studies that have proposed Late Triassic as the beginning of Phosphoria oil generation and migration, and does not seem to reflect the source rock age (Permian) or the timing of re-migration (Late Cretaceous to Eocene) associated with the Laramide orogeny. The low precision of the revised regression (±21 Ma) is not unexpected for this oil family given the long duration of generation from a large geographic area of mature Phosphoria source rock, and the possible range in the initial 187Os/188Os

  6. Evaluation of the rhenium-osmium geochronometer in the Phosphoria petroleum system, Bighorn Basin of Wyoming and Montana, USA

    Science.gov (United States)

    Lillis, Paul G.; Selby, David

    2013-10-01

    Rhenium-osmium (Re-Os) geochronometry is applied to crude oils derived from the Permian Phosphoria Formation of the Bighorn Basin in Wyoming and Montana to determine whether the radiogenic age reflects the timing of petroleum generation, timing of migration, age of the source rock, or the timing of thermochemical sulfate reduction (TSR). The oils selected for this study are interpreted to be derived from the Meade Peak Phosphatic Shale and Retort Phosphatic Shale Members of the Phosphoria Formation based on oil-oil and oil-source rock correlations utilizing bulk properties, elemental composition, δ13C and δ34S values, and biomarker distributions. The δ34S values of the oils range from -6.2‰ to +5.7‰, with oils heavier than -2‰ interpreted to be indicative of TSR. The Re and Os isotope data of the Phosphoria oils plot in two general trends: (1) the main trend (n = 15 oils) yielding a Triassic age (239 ± 43 Ma) with an initial 187Os/188Os value of 0.85 ± 0.42 and a mean square weighted deviation (MSWD) of 1596, and (2) the Torchlight trend (n = 4 oils) yielding a Miocene age (9.24 ± 0.39 Ma) with an initial 187Os/188Os value of 1.88 ± 0.01 and a MSWD of 0.05. The scatter (high MSWD) in the main-trend regression is due, in part, to TSR in reservoirs along the eastern margin of the basin. Excluding oils that have experienced TSR, the regression is significantly improved, yielding an age of 211 ± 21 Ma with a MSWD of 148. This revised age is consistent with some studies that have proposed Late Triassic as the beginning of Phosphoria oil generation and migration, and does not seem to reflect the source rock age (Permian) or the timing of re-migration (Late Cretaceous to Eocene) associated with the Laramide orogeny. The low precision of the revised regression (±21 Ma) is not unexpected for this oil family given the long duration of generation from a large geographic area of mature Phosphoria source rock, and the possible range in the initial 187Os/188Os

  7. Age dating of mineralization and brittle deformation using rhenium-osmium (Re-Os) geochronology in pyrite-bitumen bearing fracture systems

    Science.gov (United States)

    Holdsworth, Robert; Dempsey, Eddie; Selby, David; Dichiarante, Anna; Finlay, Alex; Ogilvie, Steven

    2013-04-01

    The relative ages of different fault rocks are generally established using cross-cutting relationships seen in the field and thin section. However, the absolute dating of fault rock formation events remains a problematic issue. In many Phanerozoic basins, hydrocarbon (mainly bitumen)-bearing fault and fracture systems also carry sulphide minerals such as pyrite. The bitumen and pyrite are commonly enriched with rhenium (Re) so that the 187Re-187Os geochronometer can be used to date mineralization and better constrain the timing of brittle deformation. Furthermore, the determined 187Os/188Os composition of the sulphide minerals at the time of formation can yield insights into the origins of the fracture-hosted fluids. We report 3 cases of Re-Os sulphide geochronology from fracture-hosted hydrocarbon-pyrite systems offshore West of Shetland (UK) and in the nearby onshore Orcadian Basin, N Scotland. Hydrocarbon Re-Os data from the Faroe-Shetland Basin (FSB) show that there are four pulses of increased oil generation at 72 ± 5 Ma, 64 ± 4 Ma, 53 ± 14 Ma and 42 ± 6 Ma. These dates remove the need for large scale oil collection within fractured basement and Late Cretaceous reservoirs before re-migration into later Cenozoic reservoirs and agree with more recent models in which oil generation has been retarded by over pressure and that multiple pulses of generation are associated with regional inversion events that occurred during the Late Cretaceous, Paleocene and Oligocene/Miocene. The Clair oil field lies on the SE side of the FSB and a major part of the reservoir lies in Lewisian basement where hosting fractures are infilled with pyrite, calcite and bitumen. The pyrite contains low abundances of Re and Os, with Re-Os isotope compositions that are too similar to yield an isochron, whilst the associated bitumen is enriched in both Re and Os. Regression of the Re-Os data from other parts of the Clair field with the new pyrite Re-Os data obtained here yields a more

  8. Water isotope systematics: Improving our palaeoclimate interpretations

    Science.gov (United States)

    Jones, M. D.; Dee, S.; Anderson, L.; Baker, A.; Bowen, G.; Noone, D.

    2016-01-01

    The stable isotopes of oxygen and hydrogen, measured in a variety of archives, are widely used proxies in Quaternary Science. Understanding the processes that control δ18O change have long been a focus of research (e.g. Shackleton and Opdyke, 1973; Talbot, 1990 ; Leng, 2006). Both the dynamics of water isotope cycling and the appropriate interpretation of geological water-isotope proxy time series remain subjects of active research and debate. It is clear that achieving a complete understanding of the isotope systematics for any given archive type, and ideally each individual archive, is vital if these palaeo-data are to be used to their full potential, including comparison with climate model experiments of the past. Combining information from modern monitoring and process studies, climate models, and proxy data is crucial for improving our statistical constraints on reconstructions of past climate variability.As climate models increasingly incorporate stable water isotope physics, this common language should aid quantitative comparisons between proxy data and climate model output. Water-isotope palaeoclimate data provide crucial metrics for validating GCMs, whereas GCMs provide a tool for exploring the climate variability dominating signals in the proxy data. Several of the studies in this set of papers highlight how collaborations between palaeoclimate experimentalists and modelers may serve to expand the usefulness of palaeoclimate data for climate prediction in future work.This collection of papers follows the session on Water Isotope Systematics held at the 2013 AGU Fall Meeting in San Francisco. Papers in that session, the breadth of which are represented here, discussed such issues as; understanding sub-GNIP scale (Global Network for Isotopes in Precipitation, (IAEA/WMO, 2006)) variability in isotopes in precipitation from different regions, detailed examination of the transfer of isotope signals from precipitation to geological archives, and the

  9. Isotope systematics of Icelandic thermal fluids

    Science.gov (United States)

    Stefánsson, Andri; Hilton, David R.; Sveinbjörnsdóttir, Árný E.; Torssander, Peter; Heinemeier, Jan; Barnes, Jaime D.; Ono, Shuhei; Halldórsson, Sæmundur Ari; Fiebig, Jens; Arnórsson, Stefán

    2017-05-01

    Thermal fluids in Iceland range in temperature from 440 °C and are dominated by water (> 97 mol%) with a chloride concentration from 20,000 ppm. The isotope systematics of the fluids reveal many important features of the source(s) and transport properties of volatiles at this divergent plate boundary. Studies spanning over four decades have revealed a large range of values for δD (- 131 to + 3.3‰), tritium (- 0.4 to + 13.8 TU), δ18O (- 20.8 to + 2.3‰), 3He/4He (3.1 to 30.4 RA), δ11B (- 6.7 to + 25.0‰), δ13C∑ CO2 (- 27.4 to + 4.6‰), 14C∑ CO2 (+ 0.6 to + 118 pMC), δ13CCH4 (- 52.3 to - 17.8‰), δ15N (- 10.5 to + 3.0‰), δ34S∑ S- II (- 10.9 to + 3.4‰), δ34SSO4 (- 2.0 to + 21.2‰) and δ37Cl (- 1.0 to + 2.1‰) in both liquid and vapor phases. Based on this isotopic dataset, the thermal waters originate from meteoric inputs and/or seawater. For other volatiles, degassing of mantle-derived melts contributes to He, CO2 and possibly also to Cl in the fluids. Water-basalt interaction also contributes to CO2 and is the major source of H2S, SO4, Cl and B in the fluids. Redox reactions additionally influence the composition of the fluids, for example, oxidation of H2S to SO4 and reduction of CO2 to CH4. Air-water interaction mainly controls N2, Ar and Ne concentrations. The large range of many non-reactive volatile isotope ratios, such as δ37Cl and 3He/4He, indicate heterogeneity of the mantle and mantle-derived melts beneath Iceland. In contrast, the large range of many reactive isotopes, such as δ13C∑ CO2 and δ34S∑ S- II, are heavily affected by processes occurring within the geothermal systems, including fluid-rock interaction, depressurization boiling, and isotopic fractionation between secondary minerals and the aqueous and vapor species. Variations due to these geothermal processes may exceed differences observed among various crust and mantle sources, highlighting the importance and effects of chemical reactions on the isotope

  10. Volatile element isotope systematics of volcanic geothermal fluids, Krafla Iceland

    Science.gov (United States)

    Stefansson, A.; Gunnarsson Robin, J.; Keller, N. S.; Ono, S.; Barnes, J.

    2015-12-01

    Among the major goals of geothermal geochemistry is to identify the source of the geothermal fluids and the processes influencing their chemical composition. Such can be difficult given that geothermal systems are characterized by many phases (vapor, liquid and solid) and components. Here we report data on volatile element stable isotope systematics (H2O, CO2, Cl, H2S and SO4) in volcanic geothermal fluids at Krafla, NE Iceland. Fluid temperatures ranged from 192 to 437°C. The sources and reactions of these volatile elements is commonly based on identifying the variable end-member components in the system and their respective mixing ratios, or alternatively, comparing temperature dependence of isotope fractionation of given reactions with the measured isotope systematics. Isotopes of a given element fractionates upon reactions with key reactions in geothermal systems being aqueous speciation, vapor-water partitioning and water-rock interactions, these depending on solution composition, temperature and pressure. In order to study the effects of various reactions and processes affecting isotope systematics of geothermal fluids and to reconstruct reservoir isotope systematics, isotope geochemical models were developed by combining aqueous speciation, gas-water partitioning and water-rock modelling together with isotope fractionation and isotope mass action equations. Based on these models and data collected at Krafla it is concluded that the key factors controlling, reactive volatile element isotope systematics (S and C) are two, the isotope composition of the source material and isotope fractionation associated with aqueous and vapor speciation and how these changes as a function of processes occurring in the system including boiling and fluid-rock interaction, whereas the non-reactive element isotope systematics (Cl) is controlled their various end-member components in the system and their respective mixing ratios. Based on these data and models, the reservoir C, S

  11. Iron isotope systematics of the Skaergaard intrusion

    DEFF Research Database (Denmark)

    Lesher, Charles; Lundstrom, C.C.; Barfod, Gry

    crystallization on non-traditional stable isotope systems, particularly iron. FeTi oxide minerals (titanomagnetite and ilmenite) appear after ~60% of the magma had solidified. This was a significant event affecting the liquid line of descent and potentially accompanied by iron isotope fractionation. Here we...... report the results of a broad study of the iron isotope compositions of gabbros within the layered and upper border series of the Skaergaard intrusion, pegmatite and granophyre associated with these gabbroic rocks, and the sandwich horizon thought to represent the product of extreme differentiation and....... Forward modeling of closed system fractional crystallization constrained by cumulate volumes, whole rock and mineral compositions, mineral modes and independent constraints on Fe isotope fractionation factors account for the stratigraphic relations, except during the final stages of differentiation...

  12. Magnesium isotope systematics in Martian meteorites

    Science.gov (United States)

    Magna, Tomáš; Hu, Yan; Teng, Fang-Zhen; Mezger, Klaus

    2017-09-01

    Magnesium isotope compositions are reported for a suite of Martian meteorites that span the range of petrological and geochemical types recognized to date for Mars, including crustal breccia Northwest Africa (NWA) 7034. The δ26Mg values (per mil units relative to DSM-3 reference material) range from -0.32 to -0.11‰; basaltic shergottites and nakhlites lie to the heavier end of the Mg isotope range whereas olivine-phyric, olivine-orthopyroxene-phyric and lherzolitic shergottites, and chassignites have slightly lighter Mg isotope compositions, attesting to modest correlation of Mg isotopes and petrology of the samples. Slightly heavier Mg isotope compositions found for surface-related materials (NWA 7034, black glass fraction of the Tissint shergottite fall; δ26Mg > -0.17‰) indicate measurable Mg isotope difference between the Martian mantle and crust but the true extent of Mg isotope fractionation for Martian surface materials remains unconstrained. The range of δ26Mg values from -0.19 to -0.11‰ in nakhlites is most likely due to accumulation of clinopyroxene during petrogenesis rather than garnet fractionation in the source or assimilation of surface material modified at low temperatures. The rather restricted range in Mg isotope compositions between spatially and temporally distinct mantle-derived samples supports the idea of inefficient/absent major tectonic cycles on Mars, which would include plate tectonics and large-scale recycling of isotopically fractionated surface materials back into the Martian mantle. The cumulative δ26Mg value of Martian samples, which are not influenced by late-stage alteration processes and/or crust-mantle interactions, is - 0.271 ± 0.040 ‰ (2SD) and is considered to reflect δ26Mg value of the Bulk Silicate Mars. This value is robust taking into account the range of lithologies involved in this estimate. It also attests to the lack of the Mg isotope variability reported for the inner Solar System bodies at current

  13. Iron isotope systematics in planetary reservoirs

    Science.gov (United States)

    Sossi, Paolo A.; Nebel, Oliver; Foden, John

    2016-10-01

    Iron is the only polyvalent major element, and controls reduction-oxidation (redox) reactions in a host of geologic processes and reservoirs, from the mineral- to planetary-scale, on Earth and in space. Mass transfer of Fe is often accompanied by changes in bonding environment, meaning the resultant variation in bond-strength in crystals, liquids and gases induces stable isotope fractionation, even at high temperatures. In the absence of iron exchange, electron transfer can also affect iron's valence state and calculated oxygen fugacity (fO2), however its isotope composition remains unchanged. Thus, iron isotopes are a powerful tool to investigate processes that involve mass transfer, redox reactions and changes in bonding environment in planetary systems. Primitive chondritic meteorites show remarkable isotopic homogeneity, δ57 Fe = - 0.01 ± 0.01 ‰ (2SE), over a wide range of Fe/Mg vs Ni/Mg, a proxy for fO2 in the solar nebula. In chondrites, there are iron isotope differences between metal and silicates that become more pronounced at higher metamorphic grades. However, on a planetary scale, Mars and Vesta overlap with chondrites, preserving no trace of core formation or volatile depletion on these bodies. Upon assessment of pristine lherzolites, the Bulk Silicate Earth is heavier than chondrites (δ57 Fe = + 0.05 ± 0.01 ‰; 2SE), and similar to or slightly lighter than the Moon. That the mantles of some differentiated inner solar system bodies extend to heavier compositions (+ 0.2 ‰) than chondrites may principally result from volatile depletion either at a nebular or late accretion stage. Within terrestrial silicate reservoirs, iron isotopes provide insight into petrogenetic and geodynamic processes. Partial melting of the upper mantle produces basalts that are heavier than their sources, scaling with degree of melting and driving the increasingly refractory peridotite to lighter compositions. Mid-Ocean Ridge Basalts (MORBs) are homogeneous to δ57 Fe

  14. Uranium Isotope Systematic in Saanich Inlet

    Science.gov (United States)

    Amini, M.; Holmden, C.; Francois, R.

    2008-12-01

    As a redox-sensitive element Uranium has become the focus of stable isotope studies. Based on the nuclear field shift effect [1], U isotope fractionation was predicted as a function of U(IV)-U(VI) exchange reactions with the insoluble reduced U(IV) species being heavier than the soluble oxidized U(VI) species. Recently, variations in 238U/235U were reported in low temperature aqueous and sedimentary environments [2,3] indicating that U deposited in well-oxygenated environments is characterized by light isotopic composition, whereas suboxic and anoxic deposits tend towards a heavy isotopic signature. U isotope fractionation has been hence proposed as a promising new paleo-redox proxy. In order to test the efficacy of U isotope fractionation to record oxidation states in marine systems, we are investigating sediment samples deposited over a range of redox conditions in the seasonally anoxic Saanich Inlet, on the east coast of Vancouver Island. We have also made δ238U measurements for water samples from above and below the redoxcline. The measurements were carried out by MC-ICPMS using 233U/236U-double spike technique. The data are reported as δ238U relative to NBL 112a with a 238U/235U ratio of 137.88 (2sd). External precision is better than 0.10 permil (2sd). Eleven analyses of seawater performed over the course of this work yielded δ238U of -0.41±0.07 permil (2sd). No clear difference in δ238U values has been found, thus far, in water samples collected at 10m (O2~380μM) and 200m (O2~1μM) depths from a single location in the middle of the inlet. The mean of two measurements of the deepwater sample yielded -0.43±0.01 permil (2sd). Two measurements of the shallow water sample yielded a mean value of -0.38±0.03 permil (2sd). The δ238U values for HF-HNO3 digestions of the organic rich sediments, one taken in the middle of the basin (3.11% organic carbon) below seasonally anoxic bottom waters (-0.22±0.01 permil, n=2), and the other taken from the sill (1

  15. Oxygen Isotope Systematics of Almahata Sitta

    Science.gov (United States)

    Kita, N. T.; Goodrich, C. A.; Herrin, J. S.; Shaddad, M. H.; Jenniskens, P.

    2011-01-01

    The Almahata Sitta (hereafter "AHS") meteorite was derived from an impact of asteroid 2008TC3 on Earth and is classified as an anomalous polymict ureilite. More than 600 meteorite fragments have been recovered from the strewnfield. Previous reports indicate that these fragments consist mainly of ureilitic materials with textures and compositions, while some fragments are found to be chondrites of a wide range of chemical classes. Bulk oxygen three isotope analyses of ureilitic fragments from AHS fall close to the CCAM (Carbonaceous Chondrite Anhydrous Mineral) line similar to ureilites. In order to further compare AHS with known ureilites, we performed high precision SIMS (Secondary Ion Mass Spectrometer) oxygen isotope analyses of some AHS samples

  16. Extreme heterogeneity in Sr isotope systematic in the Himalayan ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 110; Issue 2. Extreme heterogeneity in Sr isotope systematic in the Himalayan leucogranites: A possible mechanism of partial melting based on thermal modeling. Dilip K Mukhopadhyay. Volume 110 Issue 2 June 2001 pp 161-169 ...

  17. Hydrogen isotope systematics of submarine basalts

    Science.gov (United States)

    Kyser, T.K.; O'Neil, J.R.

    1984-01-01

    The D/H ratios and water contents in fresh submarine basalts from the Mid-Atlantic Ridge, the East Pacific Rise, and Hawaii indicate that the primary D/H ratios of many submarine lavas have been altered by processes including (1) outgassing, (2) addition of seawater at magmatic temperature, and (3) low-temperature hydration of glass. Decreases in ??D and H2O+ from exteriors to interiors of pillows are explained by outgassing of water whereas inverse relations between ??D and H2O+ in basalts from the Galapagos Rise and the FAMOUS Area are attributed to outgassing of CH4 and H2. A good correlation between ??D values and H2O is observed in a suite of submarine tholeiites dredged from the Kilauea East Rift Zone where seawater (added directly to the magma), affected only the isotopic compositions of hydrogen and argon. Analyses of some glassy rims indicate that the outer millimeter of the glass can undergo lowtemperature hydration by hydroxyl groups having ??D values as low as -100. ??D values vary with H2O contents of subaerial transitional basalts from Molokai, Hawaii, and subaerial alkali basalts from the Society Islands, indicating that the primary ??D values were similar to those of submarine lavas. Extrapolations to possible unaltered ??D values and H2O contents indicate that the primary ??D values of most thoteiite and alkali basalts are near -80 ?? 5: the weight percentages of water are variable, 0.15-0.35 for MOR tholeiites, about 0.25 for Hawaiian tholeiites, and up to 1.1 for alkali basalts. The primary ??D values of -80 for most basalts are comparable to those measured for deep-seated phlogopites. These results indicate that hydrogen, in marked contrast to other elements such as Sr, Nd, Pb, and O, has a uniform isotopic composition in the mantle. This uniformity is best explained by the presence of a homogeneous reservoir of hydrogen that has existed in the mantle since the very early history of the Earth. ?? 1984.

  18. Stable Isotope Systematics of Coalbed Gas during Desorption and Production

    Directory of Open Access Journals (Sweden)

    Martin Niemann

    2017-06-01

    Full Text Available The stable carbon isotope ratios of coalbed methane (CBM demonstrate diagnostic changes that systematically vary with production and desorption times. These shifts can provide decisive, predictive information on the behaviour and potential performance of CBM operations. Samples from producing CBM wells show a general depletion in 13C-methane with increasing production times and corresponding shifts in δ13C-CH4 up to 35.8‰. Samples from canister desorption experiments show mostly enrichment in 13C for methane with increasing desorption time and isotope shifts of up to 43.4‰. Also, 13C-depletion was observed in some samples with isotope shifts of up to 32.1‰. Overall, the magnitudes of the observed isotope shifts vary considerably between different sample sets, but also within samples from the same source. The δ13C-CH4 values do not have the anticipated signature of methane generated from coal. This indicates that secondary processes, including desorption and diffusion, can influence the values. It is also challenging to deconvolute these various secondary processes because their molecular and isotope effects can have similar directions and/or magnitudes. In some instances, significant alteration of CBM gases has to be considered as a combination of secondary alteration effects.

  19. Isotope systematic of contaminant leads in Monterey Bay

    Energy Technology Data Exchange (ETDEWEB)

    Flegal, A.R.; Rosman, K.J.R.; Stephenson, M.D.

    1987-11-01

    Isotopic compositions of stable lead (/sup 204/Pb, /sup 206/Pb, /sup 207/Pb, and /sup 208/Pb) were utilized to identify a lead slag deposit as the principal source of contaminant lead in Monterey Bay. This point source had been indicated by anomalously high lead concentrations in native mussels (Mytilus californianus) near that deposit, which were orders of magnitude above the base-line concentration of the species (0.5 ..mu..g/g). Subsequent analyses revealed that the lead concentrations of both transplanted mussels and intertidal sediments were positively correlated with their proximity to the slag deposit. Complementary lead isotopic compositions substantiated those empirical correlations by demonstrating that the slag was the predominant source of contaminant lead in both the mussels and the sediments. Analyses of the digestive tracts of mussels from the slag deposit indicated that ingested slag particulates accounted for their elevated lead concentrations, while analyses of their gonads indicated that dissolved lead from other industrial sources was also being bioaccumulated by passive adsorption on exposed surfaces. Therefore, this study has demonstrated the potential of lead isotope systematics both to identify sources of lead contamination in marine organisms and to trace its biogeochemical cycle in the marine environment. 26 references, 3 figures, 5 tables.

  20. Iron and lithium isotope systematics of the Hekla volcano, Iceland - Evidence for Fe isotope fractionation during magma differentiation

    OpenAIRE

    J. A. Schuessler; R. Schönberg; O. Sigmarsson; [Amhurst, Nicholas] 

    2009-01-01

    In this study potential iron isotope fractionation by magmatic processes in the Earth's crust was systematically investigated. High precision iron isotope analyses by MC-ICP-MS were performed on a suite of rock samples representative for the volcanic evolution of the Hekla volcano, Iceland. The whole series of Hekla's rocks results from several processes. (i) Basaltic magmas rise and induce partial melting of metabasalts in the lower part of the Icelandic crust. The resulting dacitic magma ev...

  1. New systematic features in the neutron-deficient Au isotopes

    Science.gov (United States)

    Venhart, M.; Wood, J. L.; Sedlák, M.; Balogh, M.; Bírová, M.; Boston, A. J.; Cocolios, T. E.; Harkness-Brennan, L. J.; Herzberg, R.-D.; Holub, L.; Joss, D. T.; Judson, D. S.; Kliman, J.; Klimo, J.; Krupa, L.; Lušnák, J.; Makhathini, L.; Matoušek, V.; Motyčák, Š.; Page, R. D.; Patel, A.; Petrík, K.; Podshibyakin, A. V.; Prajapati, P. M.; Rodin, A. M.; Špaček, A.; Urban, R.; Unsworth, C.; Veselský, M.

    2017-07-01

    A recently developed portable, on-line capability for γ-ray and conversion-electron spectroscopy, HIGH-TATRA is demonstrated with its application to the study of 183Hg \\to 183Au at ISOLDE. Key details of the low-energy level scheme of the neutron-deficient nuclide 183Au populated in this decay are presented. A broad energy germanium detector is employed to achieve this (the first-ever use of such a device in decay-scheme spectroscopy), by way of a combination of high-gain γ-ray singles spectroscopy and γ-γ coincidence spectroscopy. Further, by combining the γ-ray detectors with a liquid-nitrogen-cooled Si(Li) detector operated under high vacuum, conversion-electron singles and e-γ coincidences are obtained. These data lead to the determination of transition multipolarities and the location of a highly converted (E0 + M1 + E2) transition in the 183Au decay scheme, suggesting a possible new shape coexisting structure in this nucleus. Identification of new intruder and normal states fixes their relative energies in 183Au for the first time. New systematic features in the odd-Au isotopes are presented.

  2. LU-HF Age and Isotope Systematics of ALH84001

    Science.gov (United States)

    Righter, M.; Lapen, T. J.; Brandon, A. D.; Beard, B. L.; Shafer, J. T.; Peslier, A. H.

    2009-01-01

    Allan Hills (ALH) 84001 is an orthopyroxenite that is unique among the Martian meteorites in having the oldest inferred crystallization age (approx..4.5 to 4.0 Gyr) [e.g., 1-6 and references therein 7]. Its ancient origin makes this stone a critical constraint on early history of Mars, in particular the evolution of different planetary crust and mantle reservoirs. However, because there is significant variability in reported crystallization ages, determination of initial isotope compositions is imprecise making assessment of planetary reservoirs difficult. Here we report a new Lu-Hf mineral isochron age, initial Hf-176/Hf-177 isotope composition, and inferred Martian mantle source compositions for ALH84001 that place constraints on longlived source reservoirs for the enriched shergottite suite of Martian meteorites including Shergotty, Zagami, NWA4468, NWA856, RBT04262, LAR06319, and Los Angeles. Sm-Nd isotope analyses are under way for the same mineral aliquots analyzed for Lu-Hf. The Lu-Hf system was utilized because Lu and Hf are both lithophile and refractory and are not easily redistributed during short-lived thermal pulses associated with shock metamorphism. Moreover, chromite has relatively modest Hf concentrations with very low Lu/Hf ratios [9] yielding tight constraints on initial Hf-176/Hf-177 isotope compositions

  3. Stable isotope systematics of surface water bodies in the Himalayan ...

    Indian Academy of Sciences (India)

    Stable hydrogen (D) and oxygen (18O) isotope ratios of the headwaters of the Indus and its tributaries, surface ice in glaciers, saline and fresh water lakes and thermal springs in the Himalayan and Trans- Himalayan (Kashmir) region are reported. The D-18O relationship for the river samples shows a slope of 9.12 ...

  4. INTERACTION OF INTERSTITIAL CLUSTERS WITH RHENIUM, OSMIUM, AND TANTALUM IN TUNGSTEN

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Wahyu; Nandipati, Giridhar; Kurtz, Richard J.

    2016-09-01

    In the previous semi annual report, we explored the stability of interstitial clusters in W up to size seven. In this report, we study the binding of those clusters to Re, Os, and Ta atoms. For each cluster size, the three most stable configurations are considered to average the binding property. The average binding energy to a Re decreases from 0.79 eV for a size-1 cluster (a [111] dumbbell) to 0.65 eV for a size-7 cluster. For Os, the binding decreases from 1.61 eV for a [111] dumbbell to 1.34 eV for a size-7 cluster. Tantalum is repulsive to interstitial clusters with binding energy ranges from -0.61 eV for a [111] dumbbell to -0.5 eV for a size-7 cluster.

  5. Triple oxygen isotope systematics of structurally bonded water in gypsum

    Science.gov (United States)

    Herwartz, Daniel; Surma, Jakub; Voigt, Claudia; Assonov, Sergey; Staubwasser, Michael

    2017-07-01

    The triple oxygen isotopic composition of gypsum mother water (gmw) is recorded in structurally bonded water in gypsum (gsbw). Respective fractionation factors have been determined experimentally for 18O/16O and 17O/16O. By taking previous experiments into account we suggest using 18αgsbw-gmw = 1.0037; 17αgsbw-gmw = 1.00195 and θgsbw-gmw = 0.5285 as fractionation factors in triple oxygen isotope space. Recent gypsum was sampled from a series of 10 ponds located in the Salar de Llamara in the Atacama Desert, Chile. Total dissolved solids (TDS) in these ponds show a gradual increase from 23 g/l to 182 g/l that is accompanied by an increase in pond water 18O/16O. Gsbw falls on a parallel curve to the ambient water from the saline ponds. The offset is mainly due to the equilibrium fractionation between gsbw and gmw. However, gsbw represents a time integrated signal biased towards times of strong evaporation, hence the estimated gmw comprises elevated 18O/16O compositions when compared to pond water samples taken on site. Gypsum precipitation is associated with algae mats in the ponds with lower salinity. No evidence for respective vital effects on the triple oxygen isotopic composition of gypsum hydration water is observed, nor are such effects expected. In principle, the array of δ18Ogsbw vs. 17Oexcess can be used to: (1) provide information on the degree of evaporation during gypsum formation; (2) estimate pristine meteoric water compositions; and (3) estimate local relative humidity which is the controlling parameter of the slope of the array for simple hydrological situations. In our case study, local mining activities may have decreased deep groundwater recharge, causing a recent change of the local hydrology.

  6. Systematic measurement of beta-decay half-lives of short-lived isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, T.; Yamamoto, H.; Kawade, K. [Nagoya Univ. (Japan); Iida, T.; Takahashi, A.; Kasugai, Y.; Ikeda, Y.

    1997-03-01

    We have measured the half-lives of short-lived isotopes for past decade and deduced the half-lives of 6 isotopes further. These results demonstrated that most of the literature values shorter than 10 min systematically deviated from our measurement ones. The cause seems to be that a large number of the previous half-life studies were performed with scintillation counters before 1970 and they had a difficulty in distinguishing the interest {gamma}-ray from the contamination and correcting for pile-up and dead-time losses. Moreover, the deviated data found to be quoted for evaluation. (author)

  7. Oxygen isotope systematics of chondrules in the Allende CV3 chondrite: High precision ion microprobe studies

    Digital Repository Service at National Institute of Oceanography (India)

    Rudraswami, N.G.; Ushikubo, T.; Nakashima, D.; Kita, N.T.

    . (2000) Clarity and confusion: the history of Allende chondrules as evinced by oxygen isotopes. Lunar Planet. Sci. 31 (Abstract #1881). Ash R. D., Young E. D., Rumble III, D., Alexander C. M. O’D. and MacPherson G. J. (1999) Oxygen isotope systematics... in Allende chondrules. Lunar Planet. Sci. 30 (Abstract #1836). Brearley A. J. (1997) Disordered biopyriboles, amphibole, and talc in the Allende meteorite: Products of nebular or parent body aqueous alteration? Science 276, 1103–1105. Bridges J.C., Franchi...

  8. New constraints on the Paleoarchean meteorite bombardment of the Earth - Geochemistry and Re-Os isotope signatures of spherule layers in the BARB5 ICDP drill core from the Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Schulz, Toni; Koeberl, Christian; Luguet, Ambre; van Acken, David; Mohr-Westheide, Tanja; Ozdemir, Seda; Reimold, Wolf Uwe

    2017-08-01

    Archean spherule layers, resulting from impacts by large extraterrestrial objects, to date represent the only remnants of the early meteorite, asteroid, and comet bombardment of the Earth. Only few Archean impact debris layers have been documented, all of them embedded in the 3.23-3.47 billion year old successions of the Barberton Greenstone Belt (BGB) in South Africa and the Pilbara Craton in Western Australia. Some of them might be correlated with each other. Given the scarcity of Archean spherule deposits, four spherule layer intersections from the recently recovered BARB5 drill core from the central Barberton Greenstone Belt, analyzed in this study, provide an opportunity to gain new insight into the early terrestrial impact bombardment. Despite being hydrothermally overprinted, siderophile element abundance signatures of spherule-rich samples from the BARB5 drill core, at least in part, retained a meteoritic fingerprint. The impact hypothesis for the generation of the BARB5 spherule layers is supported by correlations between the abundances of moderately (Cr, Co, Ni) and highly siderophile (Re, Os, Ir, Pt, Ru and Pd) elements, whose peak concentrations and interelement ratios are within the range of those for chondrites. Rhenium-Osmium isotope evidence further support the impact hypothesis. Collectively, this study provides evidence for extraterrestrial admixtures ranging between ∼40 and up to 100% to three of the four analyzed BARB5 spherule layers, and a scenario for their genesis involving (i) impact of a chondritic bolide into a sedimentary target, (ii) varying admixtures of meteoritic components to target materials, (iii) spherule formation via condensation in an impact vapor plume, (iv) transportation of the spherules and sedimentation under submarine conditions, followed by (v) moderate post-impact remobilization of transition metals and highly siderophile elements.

  9. Accretion timescale and impact history of Mars deduced from the isotopic systematics of martian meteorites

    Science.gov (United States)

    Borg, Lars E.; Brennecka, Gregory A.; Symes, Steven J. K.

    2016-02-01

    High precision Sm-Nd isotopic analyses have been completed on a suite of 11 martian basaltic meteorites in order to better constrain the age of silicate differentiation on Mars associated with the formation of their mantle sources. These data are used to evaluate the merits and disadvantages of various mathematical approaches that have been employed in previous work on this topic. Ages determined from the Sm-Nd isotopic systematics of individual samples are strongly dependent on the assumed Nd isotopic composition of the bulk planet. This assumption is problematic given differences observed between the Nd isotopic composition of Earth and chondritic meteorites and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of 146Sm-142Nd whole rock isochrons are not dependent on the assumed 142Nd/144Nd ratio of the planet, but require the sample suite to be derived from complementary, contemporaneously-formed reservoirs. In this work, we present a mathematical expression that defines the age of formation of the source regions of such a suite of samples that is based solely on the slope of a 143Nd-142Nd whole rock isochron and is also independent of any a priori assumptions regarding the bulk isotopic composition of the planet. This expression is also applicable to mineral isochrons and has been used to successfully calculate 143Nd-142Nd model crystallization ages of early refractory solids as well as lunar samples. This permits ages to be obtained using only Nd isotopic measurements without the need for 147Sm/144Nd isotope dilution determinations. When used in conjunction with high-precision Nd isotopic measurements completed on martian meteorites this expression yields an age of formation of the martian basaltic meteorite source regions of 4504 ± 6 Ma. Because the Sm-Nd model ages for the formation of martian source regions are commonly interpreted to record the age at which large scale

  10. A systematic regional trend in helium isotopes across the northernbasin and range province, Western North America

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, B. Mack; van Soest, Matthijs C.

    2006-05-01

    An extensive study of helium isotopes in fluids collectedfrom surface springs, fumaroles and wells across the northern Basin andRange Province reveals a systematic trend of decreasing 3He/4He ratiosfrom west to east. The western margin of the Basin and Range ischaracterized by mantle-like ratios (6-8 Ra) associated with active orrecently active crustal magma systems (e.g., Coso, Long Valley,Steamboat, and the Cascade volcanic complex). Moving towards the east,the ratios decline systematically to a background value of ~;0.1 Ra. Theregional trend is consistent with extensive mantle melting concentratedalong the western margin and is coincident with an east-to-west increasein the magnitude of northwest strain. The increase in shear strainenhances crustal permeability resulting in high vertical fluid flow ratesthat preserve the high helium isotope ratios at the surface. Superimposedon the regional trend are "helium spikes," local anomalies in the heliumisotope composition. These "spikes" reflect either local zones of mantlemelting or locally enhanced crustal permeability. In the case of theDixie Valley hydrothermal system, it appears to be a combination ofboth.

  11. Preliminary Report on U-Th-Pb Isotope Systematics of the Olivine-Phyric Shergottite Tissint

    Science.gov (United States)

    Moriwaki, R.; Usui, T.; Yokoyama, T.; Simon, J. I.; Jones, J. H.

    2014-01-01

    Geochemical studies of shergottites suggest that their parental magmas reflect mixtures between at least two distinct geochemical source reservoirs, producing correlations between radiogenic isotope compositions, and trace element abundances.. These correlations have been interpreted as indicating the presence of a reduced, incompatible-element- depleted reservoir and an oxidized, incompatible-element-rich reservoir. The former is clearly a depleted mantle source, but there has been a long debate regarding the origin of the enriched reservoir. Two contrasting models have been proposed regarding the location and mixing process of the two geochemical source reservoirs: (1) assimilation of oxidized crust by mantle derived, reduced magmas, or (2) mixing of two distinct mantle reservoirs during melting. The former clearly requires the ancient martian crust to be the enriched source (crustal assimilation), whereas the latter requires a long-lived enriched mantle domain that probably originated from residual melts formed during solidification of a magma ocean (heterogeneous mantle model). This study conducts Pb isotope and U-Th-Pb concentration analyses of the olivine-phyric shergottite Tissint because U-Th-Pb isotope systematics have been intensively used as a powerful radiogenic tracer to characterize old crust/sediment components in mantle- derived, terrestrial oceanic island basalts. The U-Th-Pb analyses are applied to sequential acid leaching fractions obtained from Tissint whole-rock powder in order to search for Pb isotopic source components in Tissint magma. Here we report preliminary results of the U-Th-Pb analyses of acid leachates and a residue, and propose the possibility that Tissint would have experienced minor assimilation of old martian crust.

  12. Proton elastic scattering from tin isotopes at 295 MeV and systematic change of neutron density distributions

    CERN Document Server

    Terashima, S; Takeda, H; Ishikawa, T; Itoh, M; Kawabata, T; Murakami, T; Uchida, M; Yasuda, Y; Yosoi, M; Zenihiro, J; Yoshida, H P; Noro, T; Ishida, T; Asaji, S; Yonemura, T

    2008-01-01

    Cross sections and analyzing powers for proton elastic scattering from $^{116,118,120,122,124}$Sn at 295 MeV have been measured for a momentum transfer of up to about 3.5 fm$^{-1}$ to deduce systematic changes of the neutron density distribution. We tuned the relativistic Love-Franey interaction to explain the proton elastic scattering of a nucleus whose density distribution is well known. Then, we applied this interaction to deduce the neutron density distributions of tin isotopes. The result of our analysis shows the clear systematic behavior of a gradual increase in the neutron skin thickness of tin isotopes with mass number.

  13. Correlations Among Microstructure, Morphology, Chemistry, and Isotopic Systematics of Hibonite in CM Chondrites

    Science.gov (United States)

    Han, J.; Liu, M.-C..; Keller, L. P.; Davis, A. M.

    2017-01-01

    Introduction: Hibonite is a primary refractory phase occurring in many CAIs, typically with spinel and perovskite. Our microstructural studies of CAIs from carbonaceous chondrites reveal a range of stacking defect densities and correlated non-stoichiometry in hibonite. We also conducted a series of annealing experiments, demonstrating that the Mg-Al substitution stabilized the formation of defect-structured hibonite. Here, we continue a detailed TEM analysis of hibonite-bearing inclusions from CM chondrites that have been well-characterized isotopically. We examine possible correlations of microstructure, morphology, mineralogy, and chemical and isotopic systematics of CM hibonites in order to better understand the formation history of hibonite in the early solar nebula. Methods: Fifteen hibonite-bearing inclusions from the Paris CM chondrite were analyzed using a JEOL 7600F SEM and a JEOL 8530F electron microprobe. In addition to three hibonite-bearing inclusions from the Murchison CM chondrite previously reported, we selected three inclusions from Paris, Pmt1-6, 1-9, and 1-10, representing a range of 26Al/27Al ratios and minor element concentrations for a detailed TEM study. We extracted TEM sections from hibonite grains using a FEI Quanta 3D field emission gun SEM/FIB. The sections were then examined using a JEOL 2500SE field-emission scanning TEM equipped with a Thermo-Noran thin window EDX spectrometer. Results and Discussion: A total of six hibonite-bearing inclusions, including two platy hibonite crystals (PLACs) and four spinel-hibonite inclusions (SHIBs), were studied. There are notable differences in chemical and isotopic compositions between the inclusions (Table 1), indicative of their different formation environment or timing. Our TEM observations show perfectly-ordered, stoichiometric hibonite crystals without stacking defects in two PLACs, 2-7-1 and 2-8-2, and in three SHIBs, Pmt1-6, 1-9, and 1-10. In contrast, SHIB 1-9-5 hibonite grains contain a

  14. Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

    Science.gov (United States)

    Thies, R.; Heinz, A.; Adachi, T.; Aksyutina, Y.; Alcantara-Núñes, J.; Altstadt, S.; Alvarez-Pol, H.; Ashwood, N.; Aumann, T.; Avdeichikov, V.; Barr, M.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boretzky, K.; Borge, M. J. G.; Burgunder, G.; Camaño, M.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkäll, J.; Chakraborty, S.; Chartier, M.; Chulkov, L. V.; Cortina-Gil, D.; Crespo, R.; Datta, U.; Díaz Fernández, P.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estradé, A.; Farinon, F.; Fraile, L. M.; Freer, M.; Freudenberger, M.; Fynbo, H. O. U.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Göbel, K.; Golubev, P.; Gonzalez Diaz, D.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Henriques, A.; Holl, M.; Ickert, G.; Ignatov, A.; Jakobsson, B.; Johansson, H. T.; Jonson, B.; Kalantar-Nayestanaki, N.; Kanungo, R.; Knöbel, R.; Kröll, T.; Krücken, R.; Kurcewicz, J.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lepyoshkina, O.; Lindberg, S.; Machado, J.; Marganiec, J.; Maroussov, V.; Mostazo, M.; Movsesyan, A.; Najafi, A.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Perea, A.; Petri, M.; Pietri, S.; Plag, R.; Prochazka, A.; Rahaman, A.; Rastrepina, G.; Reifarth, R.; Ribeiro, G.; Ricciardi, M. V.; Rigollet, C.; Riisager, K.; Röder, M.; Rossi, D.; Sanchez del Rio, J.; Savran, D.; Scheit, H.; Simon, H.; Sorlin, O.; Stoica, V.; Streicher, B.; Taylor, J. T.; Tengblad, O.; Terashima, S.; Togano, Y.; Uberseder, E.; Van de Walle, J.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Weigand, M.; Wheldon, C.; Wilson, G.; Wimmer, C.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M. V.; Zilges, A.; Zuber, K.; R3B Collaboration

    2016-05-01

    Background: Models describing nuclear fragmentation and fragmentation fission deliver important input for planning nuclear physics experiments and future radioactive ion beam facilities. These models are usually benchmarked against data from stable beam experiments. In the future, two-step fragmentation reactions with exotic nuclei as stepping stones are a promising tool for reaching the most neutron-rich nuclei, creating a need for models to describe also these reactions. Purpose: We want to extend the presently available data on fragmentation reactions towards the light exotic region on the nuclear chart. Furthermore, we want to improve the understanding of projectile fragmentation especially for unstable isotopes. Method: We have measured projectile fragments from 10,12 -18C and B-1510 isotopes colliding with a carbon target. These measurements were all performed within one experiment, which gives rise to a very consistent data set. We compare our data to model calculations. Results: One-proton removal cross sections with different final neutron numbers (1 p x n ) for relativistic 10,12 -18C and B-1510 isotopes impinging on a carbon target. Comparing model calculations to the data, we find that the epax code is not able to describe the data satisfactorily. Using abrabla07 on the other hand, we find that the average excitation energy per abraded nucleon needs to be decreased from 27 MeV to 8.1 MeV. With that decrease abrabla07 describes the data surprisingly well. Conclusions: Extending the available data towards light unstable nuclei with a consistent set of new data has allowed a systematic investigation of the role of the excitation energy induced in projectile fragmentation. Most striking is the apparent mass dependence of the average excitation energy per abraded nucleon. Nevertheless, this parameter, which has been related to final-state interactions, requires further study.

  15. Systematic analysis of hot Yb{sup *} isotopes using the energy density formalism

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Deepika; Sharma, Manoj K.; Rajni [Thapar University, School of Physics and Materials Science, Patiala (India); Kumar, Raj [University of Padova, Department of Physics and Astronomy, Padova (Italy); Gupta, Raj K. [Panjab University, Department of Physics, Chandigarh (India)

    2014-10-15

    A systematic study of the spin-orbit density interaction potential is carried out, with spherical as well as deformed choices of nuclei, for a variety of near-symmetric and asymmetric colliding nuclei leading to various isotopes of the compound nucleus Yb{sup *}, using the semiclassical extended Thomas-Fermi formulation (ETF) of the Skyrme energy density formalism (SEDF). We observe that the spin-orbit density interaction barrier height (V{sub JB}) and barrier position (R{sub JB}) increase systematically with the increase in number of neutrons in both the projectile and target, for spherical systems. On allowing deformation effects with optimum orientations, the barrier-height increases by a large order of magnitude, as compared to the spherical case, in going from {sup 156}Yb{sup *} to {sup 172}Yb{sup *} nuclear systems formed via near-symmetric Ni+Mo or asymmetric O+Sm colliding nuclei, except that for the oblate-shaped nuclei, the V{sub JB} is the highest and R{sub JB} shifts towards a smaller (compact) interaction radius. The temperature does not change the behavior of spin-orbit density dependent (V{sub J}) and independent (V{sub P}) interaction potentials, except for some minor changes in the magnitude. The orientation degree of freedom also plays an important role in modifying the barrier characteristics and hence produces a large effect on the fusion cross section. The fusion excitation function of the compound nuclei {sup 160,} {sup 164}Yb{sup *} formed in different incoming channels, show clearly that the new forces GSkI and KDE0v1 respond better than the old SIII force. Among the first two, KDE0v1 seems to perform better. The fusion cross-sections are also predicted for a few other isotopes of Yb{sup *}. (orig.)

  16. Re-187-Os-187, Pt-190-Os-186 Isotopic and Highly Siderophile Element Systematics of Group IVA Irons

    Science.gov (United States)

    Walker, R. J.; McCoy, T. J.; Schulte, R. F.; McDonough, W. F.; Ash, R. D.

    2005-01-01

    We have recently completed Re-187-Os-187 and Pt-190-Os-186 isotopic and elemental studies of the two largest magmatic iron meteorite groups, IIAB and IIIAB [1]. These studies revealed closed-system behavior of both isotopic systems, but complex trace element behavior for Re, Pt and Os in group IIIAB. Here we examine isotopic and trace elemental systematics of group IVA irons. The IVA irons are not as extensively fractionated as IIAB and IIIAB and their apparently less complex crystallization history may make for more robust interpretation of the relative partitioning behavior of Re, Pt and Os, as well as the other highly siderophile elements (HSE) measured here; Pd, Ru and Ir [e.g. 2]. An additional goal of our continuing research plan for iron meteorites is to assess the possibility of relating certain ungrouped irons with major groups via trace element modeling. Here, the isotopic and trace element systematics of the ungrouped irons Nedagolla and EET 83230 are compared with the IVA irons.

  17. Applications of UThPb isotope systematics to the problems of radioactive waste disposal

    Science.gov (United States)

    Stuckless, J.S.

    1986-01-01

    mobility can be obtained through the use of isotopic studies. Such information can be extremely important in the search for favorable hosts for containment of radioactive waste. Rocks such as the Go??temar Granite have undergone considerable rock-water interaction, most of which occurred ??? 400 Myr. ago and little in recent times. Thus a search for zones that have experienced only a little interaction with water may provide a misleading prediction as to the ability of such zones to shield radioactive wastes from the modern biosphere. From an isotopic point of view, an ideal candidate for evaluation as a host rock for radioactive wastes would have the following characteristics: (1) a high ratio (> 2) of radiogenic to common Pb in order to optimize precision of the results; (2) a simple two-stage geologic history so that results could be interpreted without multiple working hypotheses; and (3) an originally high percentage (> 50%) of labile U so that the results would be highly sensitive to even small amount of rock-water interaction. These characteristics should produce rocks with marked radioactive disequilibrium in surface samples. The disequilibrium should grade to radioactive equilibrium with increasing depth until zones in which water has not circulated are found. Extensive regions of such zones must exist because UThPb systematics of most analyzed granitoids demonstrate closed-system behavior for almost all of their history except for their recent history in the near-surface environment. ?? 1986.

  18. Rb–Sr and Sm–Nd isotope systematics and geochemical studies on ...

    Indian Academy of Sciences (India)

    Magmas representing BBA group of samples do not show evidence for crustal contamination while magmas representing type-II rhyolites had undergone variable extents of assimilation of Mesoarchean continental crust (< 3.3 Ga) as evident from their initial Nd isotope values. Trace element and Nd isotope characteristics ...

  19. Lu-Hf isotope systematics of fossil biogenic apatite and their effects on geochronology

    Science.gov (United States)

    Herwartz, Daniel; Münker, Carsten; Tütken, Thomas; Hoffmann, J. Elis; Wittke, Andreas; Barbier, Bruno

    2013-01-01

    Reliable methods for direct dating of biogenic apatite from pre-Pleistocene fossils are currently not available, and recent attempts using the Lu-Hf decay system yielded highly inaccurate ages for both bones and teeth. The geological processes accounting for this poor accuracy of Lu-Hf chronometry are not yet understood. Here we explore Lu-Hf systematics in fossil bones and teeth in detail, by applying five different sample digestion techniques that are tested on bones and composites of bone and sediment. Our current dataset implies that dissolution methods only slightly affect the resulting Lu-Hf ages, while clear differences between the individual digestion techniques became apparent for element concentrations. By analysing the insoluble leftovers from incomplete sample dissolution, four main reservoirs of Hf in fossil bones were identified: (1) a radiogenic end-member associated with apatite; (2) an unradiogenic end-member represented by the authigenic minerals or the embedding sediment; (3) a highly unradiogenic end-member that can be attributed to detrital zircon; and (4) a moderately soluble phase (probably a Zr(Hf)-phosphate) that yielded very low Lu/Hf but a highly radiogenic Hf isotope composition at the same time. This Zr(Hf)-phase must have been precipitated within the fossil bone sample at a late stage of burial history, thereby incorporating radiogenic 176Hf released from apatite surfaces over geological timescales. A second focus of our study is the effect of different sediment matrices and of crystal size on the preservation of pristine Lu-Hf isotope compositions in bioapatite. Because near-depositional Lu-Hf ages of phosphate fossils have previously been reported for the London Clay (England) and a calcareous marl from Tendaguru (Tanzania), we herein investigate specimens fossilised in carbonate matrices (calcareous marl from Oker, Germany; carbonate concretions from the Santana Formation, Brazil; carbonate from the Eifel, Germany) and argillaceous

  20. Spectroscopy of 54Ti and the systematic behavior of low-energy octupole states in Ca and Ti isotopes

    Science.gov (United States)

    Riley, L. A.; Agiorgousis, M. L.; Baugher, T. R.; Bazin, D.; Blanchard, R. L.; Bowry, M.; Cottle, P. D.; DeVone, F. G.; Gade, A.; Glowacki, M. T.; Kemper, K. W.; Kustina, J. S.; Lunderberg, E.; McPherson, D. M.; Noji, S.; Piekarewicz, J.; Recchia, F.; Sadler, B. V.; Scott, M.; Weisshaar, D.; Zegers, R. G. T.

    2017-12-01

    Excited states of the N =32 nucleus 54Ti have been studied, via both inverse-kinematics proton scattering and one-neutron knockout from 55Ti by a liquid hydrogen target, using the GRETINA γ -ray tracking array. Inelastic proton-scattering cross sections and deformation lengths have been determined. A low-lying octupole state has been tentatively identified in 54Ti for the first time. A comparison of (p ,p') results on low-energy octupole states in the neutron-rich Ca and Ti isotopes with the results of random phase approximation calculations demonstrates that the observed systematic behavior of these states is unexpected.

  1. Rapid Communication: Δ v=2 seniority changing transitions in yrast 3^- states and B(it{E}3) systematics of Sn isotopes

    Science.gov (United States)

    Maheshwari, Bhoomika; Garg, Swati; Jain, Ashok Kumar

    2017-11-01

    We show for the first time that the generalized seniority scheme explains reasonably well the B( E3) systematics for the (0^+ → 3_1^-) transitions in the Sn isotopes, which are odd-tensor E3 transitions connecting different seniority states (Δ v = 2). Additionally, we also present large scale shell model (LSSM) calculations to support our interpretation. The generalized seniority scheme points to the octupole character of these 3^- states in Sn isotopes.

  2. A Systematic Regional Trend in Helium Isotopes Across the NorthernBasin and Range Province, Western North America

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, B. Mack; van Soest, Matthijs C.

    2005-03-22

    An extensive study of helium isotopes in fluids collectedfrom surface springs, fumaroles and wells across the northern Basin andRange Province reveals a systematic trend of decreasing 3He/4He ratiosfrom west to east. The western margin of the Basin and Range ischaracterized by mantle-like ratios (6-8 Ra) associated with active orrecently active crustal magma systems (e.g. Coso, Long Valley, Steamboat,and the Cascade volcanic complex). Moving towards the east, the ratiosdecline systematically to a background value of ~;0.1 Ra. The regionaltrend is consistent with extensive mantle melting concentrated along thewestern margin and is coincident with an east-to-west increase in themagnitude of northwest strain. The increase in shear strain enhancescrustal permeability resulting in high vertical fluid flow rates thatpreserve the high helium isotope ratios at the surface. Superimposed onthe regional trend are "helium spikes", local anomalies in the heliumisotope composition. These "spikes" reflect either local zones of mantlemelting or locally enhanced crustal permeability. In the case of theDixie Valley hydrothermal system, it appears to be a combination ofboth.

  3. Experiments for a systematic comparison between stable-isotope-(deuterium) labeling and radio-((14)C) labeling for the elucidation of the in vitro metabolic pattern of pharmaceutical drugs.

    Science.gov (United States)

    Grunwald, Helge; Hargreaves, Patrick; Gebhardt, Klaus; Klauer, Dominique; Serafyn, Arnaud; Schmitt-Hoffmann, Anne; Schleimer, Michael; Schlotterbeck, Goetz; Wind, Mathias

    2013-11-01

    A systematic comparison between two labeling approaches for the investigation of the in vitro metabolic pattern of pharmaceutical drugs was performed by examining the use of (i) radiolabeled drugs analyzed with LC-MS-offline radiodetection and (ii) stable-isotope labeled drugs, used in a defined mixture with the unlabeled drug and analyzed by LC-MS with recognition of the specific isotopic pattern. (14)C was used for the radioisotope-approach and deuterium for the stable-isotope approach. Olanzapine, diclofenac and ketoconazole were chosen as model drugs, as they are commercially available in their non-, radio- and stable-isotope labeled forms. For all three model drugs, liver microsome- and hepatocyte-incubations (both from rat) were performed with various concentrations and incubation times for both, the radio- and the stable-isotope approaches. The metabolic pattern, including structure elucidation of all detected metabolites, was performed independently for all individual compounds and incubations. Subsequently, the metabolic patterns of the radio-, and the stable-isotope approaches were compared. In conclusion, all metabolites found with the radioisotope approach could also be found with the stable-isotope approach. Although the stable-isotope approach does not provide a quantitative result, it can be considered to be a highly suited analytical alternative for early in vitro metabolism investigations, especially when radiolabeled drug analogues are not yet available and quantitative results are not yet necessary. © 2013 Elsevier B.V. All rights reserved.

  4. Highly Siderophile Elements and Osmium Isotope Systematics in Ureilites: Are the Carbonaceous Veins Primary Components?

    Science.gov (United States)

    Rankenburg, K.; Brandon, A. D.; Humayun, M.

    2005-03-01

    An unsolved problem of ureilite research is the question of whether their carbon and associated metal are primary phases. We present Os isotope data for 18 bulk ureilites and compare HSE patterns to unravel the history of the ureilite parent body.

  5. Tracking seasonal subglacial drainage evolution of alpine glaciers using radiogenic Nd and Sr isotope systematics: Lemon Creek Glacier, Alaska

    Science.gov (United States)

    Clinger, A. E.; Aciego, S.; Stevenson, E. I.; Arendt, C. A.

    2014-12-01

    The transport pathways of water beneath a glacier are subject to change as melt seasons progress due to variability in the balance between basal water pressure and water flux. Subglacial hydrology has been well studied, but the understanding of spatial distribution is less well constrained. Whereas radiogenic isotopic tracers have been traditionally used as proxies to track spatial variability and weathering rates in fluvial and riverine systems, these techniques have yet to be applied extensively to the subglacial environment and may help resolve ambiguity in subglacial hydrology. Research has shown the 143Nd/144Nd values can reflect variation in source provenance processes due to variations in the age of the continental crust. Correlating the 143Nd/144Nd with other radiogenic isotope systematics such as strontium (87Sr/86Sr) provides important constraints on the role of congruent and incongruent weathering processes. Our study presents the application of Nd and Sr systematics using isotopic ratios to the suspended load of subglacial meltwater collected over a single melt season at Lemon Creek Glacier, USA (LCG). The time-series data show an average ɛNd ~ -6.83, indicating a young bedrock (~60 MYA). Isotopic variation helps track the seasonal expansion of the subglacial meltwater channels and subsequent return to early season conditions due to the parabolic trend towards less radiogenic Nd in June and towards more radiogenic Nd beginning in mid-August. However, the high variability in July and early August may reflect a mixture of source as the channels diverge and derive sediment from differently aged lithologies. We find a poor correlation between 143Nd/144Nd and 87Sr/86Sr (R2= 0.38) along with a slight trend towards more radiogenic 87Sr/86Sr values with time ((R2= 0.49). This may indicate that, even as the residence time decreases over the melt season, the LCG subglacial system is relatively stable and that the bedrock is congruently weathered. Our study

  6. Radial mixing and Ru-Mo isotope systematics under different accretion scenarios

    Science.gov (United States)

    Fischer, Rebecca A.; Nimmo, Francis; O'Brien, David P.

    2018-01-01

    The Ru-Mo isotopic compositions of inner Solar System bodies may reflect the provenance of accreted material and how it evolved with time, both of which are controlled by the accretion scenario these bodies experienced. Here we use a total of 116 N-body simulations of terrestrial planet accretion, run in the Eccentric Jupiter and Saturn (EJS), Circular Jupiter and Saturn (CJS), and Grand Tack scenarios, to model the Ru-Mo anomalies of Earth, Mars, and Theia analogues. This model starts by applying an initial step function in Ru-Mo isotopic composition, with compositions reflecting those in meteorites, and traces compositional evolution as planets accrete. The mass-weighted provenance of the resulting planets reveals more radial mixing in Grand Tack simulations than in EJS/CJS simulations, and more efficient mixing among late-accreted material than during the main phase of accretion in EJS/CJS simulations. We find that an extensive homogeneous inner disk region is required to reproduce Earth's observed Ru-Mo composition. EJS/CJS simulations require a homogeneous reservoir in the inner disk extending to ≥3-4 AU (≥74-98% of initial mass) to reproduce Earth's composition, while Grand Tack simulations require a homogeneous reservoir extending to ≥3-10 AU (≥97-99% of initial mass), and likely to ≥6-10 AU. In the Grand Tack model, Jupiter's initial location (the most likely location for a discontinuity in isotopic composition) is ∼3.5 AU; however, this step location has only a 33% likelihood of producing an Earth with the correct Ru-Mo isotopic signature for the most plausible model conditions. Our results give the testable predictions that Mars has zero Ru anomaly and small or zero Mo anomaly, and the Moon has zero Mo anomaly. These predictions are insensitive to wide variations in parameter choices.

  7. Disturbance of isotope systematics in meteorites during shock and thermal metamorphism and implications for shergottite chronology

    Energy Technology Data Exchange (ETDEWEB)

    Gaffney, A M; Borg, L E; Asmerom, Y

    2008-12-10

    Shock and thermal metamorphism of meteorites from differentiated bodies such as the Moon and Mars have the potential to disturb chronometric information contained in these meteorites. In order to understand the impact-related mechanisms and extent of disturbance to isochrons, we undertook experiments to shock and heat samples of 10017, a 3.6 billion year old lunar basalt. One sub-sample was shocked to 55 GPa, a second subsample was heated to 1000 C for one week, and a third sub-sample was maintained as a control sample. Of the isotope systems analyzed, the Sm-Nd system was the least disturbed by shock or heat, followed by the Rb-Sr system. Ages represented by the {sup 238}U-{sup 206}Pb isotope system were degraded by shock and destroyed with heating. In no case did either shock or heating alone result in rotated or reset isochrons that represent a spurious age. In some cases the true crystallization age of the sample was preserved, and in other cases age information was degraded or destroyed. Although our results show that neither shock nor thermal metamorphism alone can account for the discordant ages represented by different isotope systems in martian meteorites, we postulate that shock metamorphism may render a meteorite more susceptible than unshocked material to subsequent disturbance during impact-related heating or aqueous alteration on Mars or Earth. The combination of these processes may result in the disparate chronometric information preserved in some meteorites.

  8. SM-ND isotopic studies of proterozoic anorthosites Systematics and implications

    Science.gov (United States)

    Ashwal, L. D.; Wooden, J. L.

    1985-01-01

    Sm-Nd isotopic studies of anorthosites can be used to provide information on their ages of crystallization and metamorphism, contamination history, and mantle sources. Proterozoic anorthosites in the Grenville and Nain Provinces of eastern North America crystallized between about 1100 and 1600 Ma, and some were metamorphosed at about 1000 Ma. Grenville Province anorthosite massifs were derived from depleted mantle. It is not clear whether massifs and related mafic intrusions throughout the Nain Province of Labrador were derived from enriched mantle, or were contaminated by early Archean (greater than 3500 Ma) silicic crustal materials, heretofore thought to be restricted to coastal Labrador.

  9. Oxygen isotope systematics in an evolving geothermal system: Coso Hot Springs, California

    Science.gov (United States)

    Etzel, Thomas M.; Bowman, John R.; Moore, Joseph N.; Valley, John W.; Spicuzza, Michael J.; McCulloch, Jesse M.

    2017-01-01

    Oxygen isotope and clay mineralogy studies have been made on whole rock samples and feldspar separates from three wells along the high temperature West Flank of the Coso geothermal system, California. The reservoir rocks have experienced variable 18O/16O depletion, with δ18O values ranging from primary values of + 7.5‰ down to - 4.6‰. Spatial patterns of clay mineral distributions in the three wells are not closely correlated with the distributions expected from measured, pre-production temperature profiles, but do correlate with spatial patterns of 18O/16O depletion, indicating that the stability of clay minerals in the three wells is a function of fluid-rock interaction in addition to temperature. Detailed δ18O measurements in the three wells identify a limited number of localized intervals of extensive 18O/16O depletion. These intervals document localized zones of higher permeability in the geothermal system that have experienced significant fluid infiltration, water-rock interaction and oxygen isotopic exchange with the geothermal fluids. The local zones of maximum 18O/16O depletion in each well correspond closely with current hot water production zones. Most feldspar separates have measured δ18O values too high to have completely attained oxygen isotope exchange equilibrium with the reservoir fluid at pre-production temperatures. In general, the lower the δ18O value of the feldspar, the closer the feldspar approaches exchange equilibrium with the geothermal fluid. This correlation suggests that fracture-induced increases in permeability increase both fluid infiltration and the surface area of the host rock exposed to geothermal fluid, promoting fluid-rock interaction and oxygen isotope exchange. The two most 18O/16O-depleted feldspar samples have δ18O values too low to be in exchange equilibrium with the pre-production reservoir fluid at pre-production temperatures. These discrepancies suggest that the reservoir fluid in the West Flank of the Coso

  10. Systematic study of proton capture rates for Mo and Cd isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Bajpeyi, Awanish; Shukla, A. [Rajiv Gandhi Institute of Petroleum Technology, Department of Physics, Raebareli (India); Koning, A.J. [Nuclear Research and Consultancy Group NRG, Petten (Netherlands); Aaberg, Sven [Lund University, Mathematical Physics, P.O. Box 118, Lund (Sweden)

    2015-12-15

    Proton capture reactions play a very important role in the understanding of nucleosynthesis. In the present work, p-capture reactions have been studied coherently with nuclear structure for the nuclei under consideration. We have calculated proton capture cross sections and S-factor for relevant isotopes of molybdenum and cadmium in the energy range 2.0 to 4.5 Mev. Calculated results for nuclear structure as well reaction rates are compared with the available experimental and theoretical results and are found to be in good agreement. (orig.)

  11. Systematic study of proton capture rates for Mo and Cd isotopes

    Science.gov (United States)

    Bajpeyi, Awanish; Koning, A. J.; Shukla, A.; Åberg, Sven

    2015-12-01

    Proton capture reactions play a very important role in the understanding of nucleosynthesis. In the present work, p-capture reactions have been studied coherently with nuclear structure for the nuclei under consideration. We have calculated proton capture cross sections and S-factor for relevant isotopes of molybdenum and cadmium in the energy range 2.0 to 4.5 Mev. Calculated results for nuclear structure as well reaction rates are compared with the available experimental and theoretical results and are found to be in good agreement.

  12. Carbon Isotope Systematics in Mineral-Catalyzed Hydrothermal Organic Synthesis Processes at High Temperature and Pressures

    Science.gov (United States)

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

    2011-01-01

    Observation of methane in the Martian atmosphere has been reported by different detection techniques. Reduction of CO2 and/or CO during serpentization by mineral surface catalyzed Fischer-Tropsch Type (FTT) synthesis may be one possible process responsible for methane generation on Mars. With the evidence a recent study has discovered for serpentinization in deeply buried carbon rich sediments, and more showing extensive water-rock interaction in Martian history, it seems likely that abiotic methane generation via serpentinization reactions may have been common on Mars. Experiments involving mineral-catalyzed hydrothermal organic synthesis processes were conducted at 750 C and 5.5 Kbars. Alkanes, alcohols and carboxylic acids were identified as organic compounds. No "isotopic reversal" of delta C-13 values was observed for alkanes or carboxylic acids, suggesting a different reaction pathway than polymerization. Alcohols were proposed as intermediaries formed on mineral surfaces at experimental conditions. Carbon isotope data were used in this study to unravel the reaction pathways of abiotic formation of organic compounds in hydrothermal systems at high temperatures and pressures. They are instrumental in constraining the origin and evolution history of organic compounds on Mars and other planets.

  13. Using stable isotope systematics and trace metals to constrain the dispersion of fish farm pollution

    Science.gov (United States)

    Torchinsky, A.; Shiel, A. E.; Price, M.; Weis, D. A.

    2010-12-01

    Fish farming is a growing industry of great economic importance to coastal communities. Unfortunately, open-net fish farming is associated with the release of organic and metal pollution, which has the potential to adversely affect the coastal marine environment. The dispersion of fish farm pollution and its environmental impact are not well understood/quantified. Pollutants released by fish farms include organic products such as uneaten feed pellets and fish feces, as well as chemicals and pharmaceuticals, all of which may enter marine ecosystems. In this study, we took advantage of bioaccumulation in passive suspension feeding Manila Clams collected at varying distances from an open-net salmon farm located in the Discovery Islands of British Columbia. Measurements of stable C and N isotopes, as well as trace metal concentrations, in the clams were used to investigate the spread of pollutants by detecting the presence of fish farm waste in the clams’ diet. Lead isotopic measurements were used to identify other significant anthropogenic pollution sources, which may impact the study area. Clams located within the areal extent of waste discharged by a fish farm are expected to exhibit anomalous light stable isotope ratios and metal concentrations, reflecting the presence of pollutants accumulated directly from seawater and from their diet. Clams were collected in the Discovery Islands from three sites in the Octopus Islands, located 850 m, 2100 m and 3000 m north of the Cyrus Rocks salmon farm (near Quadra Island) and from a reference site on Penn Island. Light stable isotope ratios (δN = ~10‰, with little variation between sites, and δC from -14.5 to -17.3‰) of the clams suggest that the most distal site (i.e., 3000 m away) is most impacted by organic fish farm waste (i.e., food pellets and feces) and that contributions of organic waste actually decrease closer to the farm. Not surprisingly, the smallest contribution of organic waste was detected in clams

  14. Uranium-lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

    Energy Technology Data Exchange (ETDEWEB)

    Gaffney, A M; Borg, L E; Connelly, J N

    2006-12-22

    Uranium-lead ratios (commonly represented as {sup 238}U/{sup 204}Pb = {mu}) calculated for the sources of martian basalts preserve a record of petrogenetic processes that operated during early planetary differentiation and formation of martian geochemical reservoirs. To better define the range of {mu} values represented by the source regions of martian basalts, we completed U-Pb elemental and isotopic analyses on whole rock, mineral and leachate fractions from the martian meteorite Queen Alexandra Range 94201 (QUE 94201). The whole rock and silicate mineral fractions have unradiogenic Pb isotopic compositions that define a narrow range ({sup 206}Pb/{sup 204}Pb = 11.16-11.61). In contrast, the Pb isotopic compositions of weak HCl leachates are more variable and radiogenic. The intersection of the QUE 94201 data array with terrestrial Pb in {sup 206}Pb/{sup 204}Pb-{sup 207}Pb/{sup 204}Pb-{sup 208}Pb/{sup 204}Pb compositional space is consistent with varying amounts of terrestrial contamination in these fractions. We calculate that only 1-7% contamination is present in the purified silicate mineral and whole rock fractions, whereas the HCl leachates contain up to 86% terrestrial contamination. Despite the contamination, we are able to use the U-Pb data to determine the initial {sup 206}Pb/{sup 204}Pb of QUE 94201 (11.086 {+-} 0.008) and calculate the {mu} value of the QUE 94201 mantle source to be 1.823 {+-} 0.008. This is the lowest {mu} value calculated for any martian basalt source, and, when compared to the highest values determined for martian basalt sources, indicates that {mu} values in martian source reservoirs vary by at least 100%. The range of source {mu} values further indicates that the {mu} value of bulk silicate Mars is approximately three. The amount of variation in the {mu} values of the mantle sources ({mu} {approx} 2-4) is greater than can be explained by igneous processes involving silicate phases alone. We suggest the possibility that a small

  15. Hydrogen, Oxygen and Silicon Isotope Systematics of Groundwater-Magma Interaction in Icelandic Hydrothermal Systems

    Science.gov (United States)

    Kleine, B. I.; Stefansson, A.; Halldorsson, S. A.; Martin, W.; Barnes, J.; Jónasson, K.; Franzson, H.

    2016-12-01

    Magma often encounters groundwater (meteoric or seawater derived) when intruded into the crust. Magma-groundwater interactions result in the formation of hydrothermal fluids which can lead to contact metamorphism and elemental transport in the country rock. In fact, magma-hydrothermal fluid interaction (rather than magma-magmatic fluid interaction) may lead to classic contact metamorphic reactions. In order to explore the importance of hydrothermal fluid during contact metamorphism we use stable isotopes (δD, δ18O, δ30Si) from both active and extinct magma chambers and hydrothermal systems from across Iceland. Quartz grains from various hydrothermal systems, from crustal xenoliths from the Askja central volcano and from the Hafnarfjall pluton, as well as quartz grains associated with low-T zeolites were analysed for δ18O and δ30Si in-situ using SIMS. Whole rock material of these samples was analysed for δD values using a TCEA coupled to an IRMS. Our results indicate that low-T quartz (300°C). Combining the results from the analyses of δ18O and δD allows further division of samples into (i) seawater and/or rock dominated and (ii) meteoric water dominated hydrothermal systems. In order to isolate the effects of fluid-rock interaction, fluid source and formation temperature at the magma-groundwater contact, δD, δ18O and δ30Si values of rocks and fluids were modeled using the PHREEQC software. Comparison of analytical and model results shows that the isotopic compositions are influenced by multiple processes. In some cases, groundwater penetrates the contact zone and causes alteration at >400°C by groundwater-magma heat interaction. Other cases document "baked" contact zones without groundwater. Our analyses and modeling demonstrates that groundwater flow and permeability are crucial in setting the style of contact metamorphism around high T intrusions.

  16. Shock Recovery and Heating Experiments on Baddeleyite: Implications for U-Pb Isotopic Systematics of Martian Meteorites

    Science.gov (United States)

    Misawa, K.; Niihara, T.; Kaiden, H.; Sekine, T.; Mikouchi, T.

    2009-12-01

    Introduction: Radiometric ages of Martian meteorites, shergottites are generally young (i.e., ~165-475 Ma), and are in the late Amazonian chronostratigraphic unit [1]. Bouvier et al. [2-4] reported ~4.1-4.3 Ga old Pb-Pb ages for shergottites, and suggested that young Rb-Sr, Sm-Nd, and Lu-Hf ages so far obtained were affected by alteration of phosphates, interaction with Martian subsurface fluids, or intense shock metamorphism. Baddeleyite (ZrO2) with apparently primary igneous morphology is an important phase in shergottites for U-Pb age determination. In order to investigate shock effects on U-Pb isotopic systematics of baddeleyite, we undertook shock recovery and heating experiments on baddeleyite. Experimental: We used coarse-grained baddeleyite from Phalaborwa for a starting material. The baddeleyite was mixed with a coarse-grained terrestrial basalt with a weight ratio of 1:2. Shock-recovery experiments were performed using a propellant gun at NIMS [5]. The run products were placed in a vertical gas-mixing furnace and heated for 1-3 h at 1000-1300oC under log fO2 of IW+2.5 at 105 Pa. Textures were observed by a scanning electron microprobe and Raman spectra of shocked baddeleyite were obtained. In situ U-Th-Pb isotopic analysis was carried out with the SHRIMP II at NIPR [6]. Results and Discussion: We observed Raman peak shifts of 2-4 cm-1 in the 34-57 GPa samples. Lead loss from baddeleyite was not observed for the experimentally shocked samples. In addition, the U-Pb and Pb-Pb ages of shocked and heated baddeleyites are indistinguishable from those of unshocked baddeleyite within errors except minor lead loss from the baddeleyite shocked at 57 GPa and heated for 1 h at 1300oC. Although duration of peak shock-pressure and grain size of baddeleyite are different from the nature of basaltic shergottites, our experimental results suggest that it is hard to completely reset U-Pb isotopic systematics of baddeleyite in Martian meteorite by shock events below ~60

  17. Cd Isotopic Composition Measured by Plasma Source Mass Spectrometry on Natural and Anthropogenic Materials. A Preliminary Outline of Cd Isotope Systematics

    Science.gov (United States)

    Innocent, C.

    2004-05-01

    Cadmium is a trace metal that is used as a geochemical tracer of natural processes, like biological productivity and paleoproductivity, and also of anthropogenic pollution, as Cd is known to be a toxic heavy metal that has become a major environmental and health concern. For these purposes, an outstanding issue is to determine whether Cd, like a number of metallic elements (e.g. Fe, Cu, Zn, Mo, Tl), may display variable isotopic compositions in natural and/or industrial compounds. It is known that Cd may display variable isotopic composition. Indeed, isotopic fractionation processes have been documented in some meteorites and in lunar soils. Consequently, due to its relatively low boiling point (767\\deg C) and also to the large mass range covered by its isotopes (10 mass units), Cd might fractionate isotopically, for example during the outpouring of acidic volcanic magmas and/or the emplacement of granitoids. On another hand, isotopic fractionation could also occur during human activities like refuse incineration or industrial manufacturing, for instance. Finally, biologically-induced isotopic fractionation should not be ruled out, as it is clearly evidenced for other metals, like Fe. A high precision method has been developed for determining the isotopic composition of Cd by plasma source mass spectrometry (Neptune). This method holds on the standard-bracketing technique, owing to the availability of Cd solutions of known isotopic composition provided by the University of M\\H{u}nster. This allows to correct precisely for mass fractionation that occurs in the plasma source mass spectrometer. It is also critical for the analysis to be possible to work with Cd solutions of very high purity. Chemical isolation of Cd involves 3 steps, and may be also suitable for Cd isotopic measurements using solid source mass spectrometry. Preliminary results suggest that Cd is likely to fractionate during smelting activities, as indicated by measurements on mining waste. The

  18. Osmium isotope and highly siderophile element systematics of the lunar crust

    Science.gov (United States)

    Day, J.M.D.; Walker, R.J.; James, O.B.; Puchtel, I.S.

    2010-01-01

    Coupled 187Os/188Os and highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundance data are reported for pristine lunar crustal rocks 60025, 62255, 65315 (ferroan anorthosites, FAN) and 76535, 78235, 77215 and a norite clast in 15455 (magnesian-suite rocks, MGS). Osmium isotopes permit more refined discrimination than previously possible of samples that have been contaminated by meteoritic additions and the new results show that some rocks, previously identified as pristine, contain meteorite-derived HSE. Low HSE abundances in FAN and MGS rocks are consistent with derivation from a strongly HSE-depleted lunar mantle. At the time of formation, the lunar floatation crust, represented by FAN, had 1.4 ?? 0.3 pg g- 1 Os, 1.5 ?? 0.6 pg g- 1 Ir, 6.8 ?? 2.7 pg g- 1 Ru, 16 ?? 15 pg g- 1 Pt, 33 ?? 30 pg g- 1 Pd and 0.29 ?? 0.10 pg g- 1 Re (??? 0.00002 ?? CI) and Re/Os ratios that were modestly elevated (187Re/188Os = 0.6 to 1.7) relative to CI chondrites. MGS samples are, on average, characterised by more elevated HSE abundances (??? 0.00007 ?? CI) compared with FAN. This either reflects contrasting mantle-source HSE characteristics of FAN and MGS rocks, or different mantle-crust HSE fractionation behaviour during production of these lithologies. Previous studies of lunar impact-melt rocks have identified possible elevated Ru and Pd in lunar crustal target rocks. The new results provide no supporting evidence for such enrichments. If maximum estimates for HSE in the lunar mantle are compared with FAN and MGS averages, crust-mantle concentration ratios (D-values) must be ??? 0.3. Such D-values are broadly similar to those estimated for partitioning between the terrestrial crust and upper mantle, with the notable exception of Re. Given the presumably completely different mode of origin for the primary lunar floatation crust and tertiary terrestrial continental crust, the potential similarities in crust-mantle HSE partitioning for the Earth and Moon are somewhat

  19. Multiple sulfur isotope systematics of Icelandic geothermal fluids and the source and reactions of sulfur in volcanic geothermal systems at divergent plate boundaries

    Science.gov (United States)

    Stefánsson, Andri; Keller, Nicole S.; Robin, Jóhann Gunnarsson; Ono, Shuhei

    2015-09-01

    Multiple sulfur isotope systematics of geothermal fluids at Krafla, Northeast Iceland, were studied in order to determine the source and reactions of sulfur in this system, as an example of a geothermal system hosted on a divergent plate boundary. Fluid temperatures ranged from 192 to 437 °C, and the fluids have low Cl concentration between ∼10 and ∼150 ppm, with liquid water and vapor being present in the reservoir. Dissolved sulfide (S-II) and sulfate (SVI) predominated in the water phase with trace concentrations of thiosulfate (S2O32-) whereas sulfide (S-II) was the only species observed in the vapor phase. The reconstructed sulfur isotope ratios of the reservoir fluids based on samples collected at surface from two-phase and vapor only well discharges indicated that δ34S and Δ33S of sulfide in the reservoir fluid ranged from -1.5 to +1.1‰ and -0.001 to -0.017‰, respectively, whereas δ34S and Δ33S of sulfate were significantly different and ranged from +3.4 to +13.4‰ and 0.000 to -0.036‰, respectively. Depressurization boiling upon fluid ascent coupled with progressive fluid-rock interaction and sulfide mineral (pyrite) formation results in the liquid phase becoming progressively isotopically lighter with respect to both δ34S and Δ33S. In contrast, H2S in the vapor phase and pyrite become isotopically heavier. The observed Δ33S and δ34S systematics for geothermal fluids at Krafla suggest that the source of sulfide in the reservoir fluids is the basaltic magma, either through degassing or upon dissolution of unaltered basalts. At high temperatures, insignificant SO4 was observed in the fluids but below ∼230 °C significant concentrations of SO4 were observed, the source inferred to be H2S oxidation. The two key factors controlling the multiple sulfur isotope systematics of geothermal fluids are: (1) the isotopic composition of the source material and (2) the isotope fractionation associated with aqueous and vapor speciation and how these

  20. Nanoscale variations in 187Os isotopic composition and HSE systematics in a Bultfontein peridotite

    Science.gov (United States)

    Wainwright, A. N.; Luguet, A.; Schreiber, A.; Fonseca, R. O. C.; Nowell, G. M.; Lorand, J.-P.; Wirth, R.; Janney, P. E.

    2016-08-01

    Understanding the mineralogical controls on radiogenic chronometers is a fundamental aspect of all geochronological tools. As with other common dating tools, it has become increasingly clear that the Re-Os system can be impacted by multiple mineral formation events. The accessory and micrometric nature of the Re-Os-bearing minerals has made assessing this influence complex. This is especially evident in cratonic peridotites, where long residence times and multiple metasomatic events have created a complex melting and re-enrichment history. Here we investigate a harzburgitic peridotite from the Bultfontein kimberlite (South Africa) which contains sub-micron Pt-Fe-alloy inclusions within base metal sulphides (BMS). Through the combination of the focused ion beam lift-out technique and low blank mass spectrometry we were able to remove and analyse the Pt-Fe-alloy inclusions for their Re-Os composition and highly siderophile element (HSE) systematics. Six repeats of the whole-rock yield 187Os/188Os compositions of 0.10893-0.10965, which correspond to Re depletion model ages (TRD) of 2.69-2.79 Ga. The Os, Ir and Pt concentrations are slightly variable across the different digestions, whilst Pd and Re remain constant. The resulting HSE pattern is typical of cratonic peridotites displaying depleted Pt and Pd. The Pt-Fe-alloys have PUM-like 187Os/188Os compositions of 0.1294 ± 24 (2-s.d.) and 0.1342 ± 38, and exhibit a saw-tooth HSE pattern with enriched Re and Pt. In contrast, their BMS hosts have unradiogenic 187Os/188Os of 0.1084 ± 6 and 0.1066 ± 3, with TRD ages of 2.86 and 3.09 Ga, similar to the whole-rock systematics. The metasomatic origin of the BMS is supported by (i) the highly depleted nature of the mantle peridotite and (ii) their Ni-rich sulphide assemblage. Occurrence of Pt-Fe-alloys as inclusions within BMS grains demonstrates the genetic link between the BMS and Pt-Fe-alloys and argues for formation during a single but continuous event of silicate melt

  1. Thermal equilibration of iron meteorite and pallasite parent bodies recorded at the mineral scale by Fe and Ni isotope systematics

    Science.gov (United States)

    Chernonozhkin, Stepan M.; Weyrauch, Mona; Goderis, Steven; Oeser, Martin; McKibbin, Seann J.; Horn, Ingo; Hecht, Lutz; Weyer, Stefan; Claeys, Philippe; Vanhaecke, Frank

    2017-11-01

    In this work, a femtosecond laser ablation (LA) system coupled to a multi-collector inductively coupled plasma-mass spectrometer (fs-LA-MC-ICP-MS) was used to obtain laterally resolved (30-80 μm), high-precision combined Ni and Fe stable isotope ratio data for a variety of mineral phases (olivine, kamacite, taenite, schreibersite and troilite) composing main group pallasites (PMG) and iron meteorites. The stable isotopic signatures of Fe and Ni at the mineral scale, in combination with the factors governing the kinetic or equilibrium isotope fractionation processes, are used to interpret the thermal histories of small differentiated asteroidal bodies. As Fe isotopic zoning is only barely resolvable within the internal precision level of the isotope ratio measurements within a single olivine in Esquel PMG, the isotopically lighter olivine core relative to the rim (Δ56/54Ferim-core = 0.059‰) suggests that the olivines were largely thermally equilibrated. The observed hint of an isotopic and concentration gradient for Fe of crudely similar width is interpreted here to reflect Fe loss from olivine in the process of partial reduction of the olivine rim. The ranges of the determined Fe and Ni isotopic signatures of troilite (δ56/54Fe of -0.66 to -0.09‰) and schreibersite (δ56/54Fe of -0.48 to -0.09‰, and δ62/60Ni of -0.64 to +0.29‰) may result from thermal equilibration. Schreibersite and troilite likely remained in equilibrium with their enclosing metal to temperatures significantly below their point of crystallization. The Ni isotopic signatures of bulk metal and schreibersite correlate negatively, with isotopically lighter Ni in the metal of PMGs and isotopically heavier Ni in the metal of the iron meteorites analyzed. As such, the light Ni isotopic signatures previously observed in PMG metal relative to chondrites may not result from heterogeneity in the Solar Nebula, but rather reflect fractionation in the metal-schreibersite system. Comparison between

  2. Hydrogen Sulfide Sequestration and Storage in Geothermal System: New Mitigation Strategy to Reduce H2S from the Atmosphere and Detect its Mineralization with Multiple Sulfur Isotopic Systematics

    Science.gov (United States)

    Marieni, C.; Stefansson, A.; Gudbrandsson, S.; Gunnarsson, I.; Aradottir, E. S.; Gunnarsson Robin, J.; Ono, S.

    2015-12-01

    Hydrogen sulfide (H2S) is one of the major components in geothermal fluids and is commonly emitted into the atmosphere from geothermal power plants causing potential environmental problems. Among several mitigation methods proposed to reduce the H2S emissions, is H2S sequestration into geothermal systems. Reykjavík Energy is undertaking a pilot project at Hellisheidi geothermal system (SW Iceland) called Sulfix project where H2S is being injected into the geothermal reservoir for permanent sequestration into pyrite. The SulFix project started its operation in June 2014: the soluble geothermal gases are dissolved in geothermal waste water, and injected at 8 bars into the high temperature reservoir (>200˚C) at 750 m below the wellhead. The reactions involving sulfur in the geothermal reservoir may be traced using sulfur fluid chemistry and multiple sulfur isotope systematics (32S, 33S, 34S and 36S), including mixing between the reservoir geothermal fluid and the injection fluid, sulfide mineralization and oxidation of sulfide to sulfate. In this study we investigated the multiple sulfur isotope systematics upon sulfide mineralization under geothermal conditions. High temperature flow through experiments were carried out in basaltic glass at 200-250°C and ~5 mmol/kg H2S to study the fluid-rock interaction. The results indicate that the sulfide mineralization occurs rapidly under geothermal conditions, highlighting the leaching rate of iron from the basaltic glass as the mineralization rate determining factor. Moreover, the formation of sulfide may be traced using the δ34S-Δ33S relationship in the fluids and pyrite formation - for example to determine if non-reactive mixing between the injection fluids and reservoir fluids occurs at Hellisheidi. The experimental results have been further supported by geochemical modeling involving multiple sulfur isotope fractionation between aqueous sulfide species and rocks upon basalt dissolution and secondary pyrite formation.

  3. Copper and zinc isotope systematics of altered oceanic crust at IODP Site 1256 in the eastern equatorial Pacific

    Science.gov (United States)

    Huang, Jian; Liu, Sheng-Ao; Gao, Yongjun; Xiao, Yilin; Chen, Sha

    2016-10-01

    This paper presents the first combined Cu and Zn isotopic study of altered oceanic crust at Integrated Ocean Drilling Program (IODP) Hole 1256D that penetrates a volcanic section, a lava-dyke transition zone, a sheeted dyke complex, and a plutonic complex. In the volcanic section, all but one rocks have Cu and Zn isotopic compositions similar to fresh mid-ocean ridge basalt (MORB), reflecting restricted seawater circulation and low oxygen fugacity. Rocks in the transition zone have MORB-like δ65Cu and δ66Zn, indicating the dominant influence of basalt-derived Cu and Zn during alteration. Rocks in the dyke complex have more variable δ65Cu (-0.50-0.90‰) and δ66Zn (0.19-0.55‰) and those in the plutonic complex have δ65Cu of -0.43 to 0.20‰ and δ66Zn of 0.21 to 0.41‰. The rocks with heavier δ66Zn and heavier or lighter δ65Cu relative to MORB are characterized by Cu-Zn depletions, low Li/Yb (<1.0) and low δ18O (<5‰), suggesting that hydrothermal extraction during high temperature alteration of oceanic crust can result in significant Cu and Zn isotope fractionation. Such large Cu and Zn isotopic variations are the results of redox transformation of Cu as well as Cu and Zn isotope fractionation between altered basaltic rocks and dissolved Cu and Zn species in hydrothermal fluids (e.g., [CuCl3]1-, Zn(HS)42-). This work is the first to define the distribution of Cu and Zn isotopes in an intact oceanic crust with concentration-weighted averages of δ65Cu (0.05 ± 0.03‰) and δ66Zn (0.27 ± 0.01‰). The potential implications of these new observations are discussed.

  4. Rb-Sr Isotopic Systematics of Alkali-Rich Fragments in the Yamato-74442 LL-Chondritic Breccia

    Science.gov (United States)

    Yokoyama, T.; Misawa, K.; Okano, O.; Shih, C.-Y.; Nyquist, L. E.; Simo, J. I.; Tappa, M. J.; Yoneda, S.

    2012-01-01

    Alkali-rich igneous fragments were identified in the brecciated LL-chondrites, Kr henberg (LL5)], Bhola (LL3-6) and Yamato (Y)-74442 (LL4), and show characteristic fractionation patterns of alkaline elements. The K-Rb-Cs-rich fragments in Kr henberg, Bhola, and Y-74442 are very similar in mineralogy and petrography (olivine + pyroxene + glass), suggesting that they could have come from related precursor materials. We have undertaken Rb-Sr isotopic studies on alkali-rich fragments in Y-74442 to precisely determine their crystallization ages and the isotopic signatures of their precursor material(s).

  5. Strontium isotope systematics of scheelite and apatite from the Felbertal tungsten deposit, Austria - results of in-situ LA-MC-ICP-MS analysis

    Science.gov (United States)

    Kozlik, Michael; Gerdes, Axel; Raith, Johann G.

    2016-02-01

    The in-situ Sr isotopic systematics of scheelite and apatite from the Felbertal W deposit and a few regional Variscan orthogneisses ("Zentralgneise") have been determined by LA-MC-ICP-MS. The 87Sr/86Sr ratios of scheelite and apatite from the deposit are highly radiogenic and remarkably scattering. In the early magmatic-hydrothermal scheelite generations (Scheelite 1 and 2) the 87Sr/86Sr ratios range from 0.72078 to 0.76417 and from 0.70724 to 0.76832, respectively. Metamorphic Scheelite 3, formed by recrystallisation and local mobilisation of older scheelite, is characterised by even higher 87Sr/86Sr values between 0.74331 and 0.80689. Statistics allows discriminating the three scheelite generations although there is considerable overlap between Scheelite 1 and 2; they could be mixtures of the same isotopic reservoirs. The heterogeneous and scattering 87Sr/86Sr ratios of the two primary scheelite generations suggest modification of the Sr isotope system due to fluid-rock interaction and isotopic disequilibrium. Incongruent release of 87Sr from micas in the Early Palaeozoic host rocks of the Habach Complex contributed to the solute budget of the hydrothermal fluids and may explain the radiogenic Sr isotope signature of scheelite. Spatially resolved analyses revealed isotopic disequilibrium even on a sub-mm scale within zoned Scheelite 2 crystals indicating scheelite growth in an isotopic dynamical hydrothermal system. Zoned apatite from the W mineralised Early Carboniferous K1-K3 orthogneiss in the western ore field yielded 87Sr/86Sr of 0.72044-0.74514 for the cores and 0.74535-0.77937 for the rims. Values of magmatic apatite cores from the K1-K3 orthogneiss are comparable to those of primary Scheelite 1; they are too radiogenic to be magmatic. The Sr isotopic composition of apatite cores was therefore equally modified during the hydrothermal mineralisation processes, therefore supporting the single-stage genetic model in which W mineralisation is associated with

  6. Diamond growth beneath Letlhakane established by Re-Os and Sm-Nd systematics of individual eclogitic sulphide, garnet and clinopyroxene inclusions

    Science.gov (United States)

    Gress, Michael U.; Pearson, D. Graham; Timmerman, Suzette; Chinn, Ingrid L.; Koornneef, Janne M.; Davies, Gareth R.

    2017-04-01

    The diamondiferous Letlhakane kimberlites are part of the Orapa kimberlite cluster (˜ 93.1 Ma) in north-eastern Botswana, located on the edge of the Zimbabwe Craton, close to the Proterozoic Magondi Mobile Belt. Here we report the first Re-Os ages of six individual eclogitic sulphide inclusions (3.0 to 35.7μg) from Letlhakane diamonds along with their rhenium, osmium, iridium and platinum concentrations, and carbon isotope, nitrogen content and N-aggregation data from the corresponding growth zones of the host diamonds. For the first time, Re-Os data will be compared to Sm-Nd ages of individual eclogitic silicate inclusions recovered from the same diamonds using a Triton Plus equipped with four 1013Ω amplifiers. The analysed inclusion set currently encompasses pairs of individual sulphides from two diamonds (LK040 sf4 & 5, LK113 sf1 & 2) and two sulphide inclusions from separate diamonds (LK048, LK362). Ongoing work will determine the Sm-Nd ages and element composition of multiple individual eclogitic garnets (LK113/LK362, n=4) and an eclogitic clinopyroxene (LK040) inclusion. TMA ages of the six sulphides range from 1.06 to 2.38 Ga (± 0.1 to 0.54 Ga) with Re and Os contents between 7 and 68 ppb and 0.03 and 0.3 ppb, respectively. The host diamond growth zones have low nitrogen abundances (21 to 43 ppm N) and high N-aggregation (53 to 90% IaB). Carbon isotope data suggests the involvement of crustal carbon (δ13C between -19.3 to -22.7 ± 0.2 per mill) during diamond precipitation. Cathodoluminescence imaging of central plates from LK040 and LK113 displays homogenous internal structure with no distinct zonation. The two sulphide inclusions from LK040 define an 'isochron' of 0.92 ± 0.23 Ga (2SD) with initial 187Os/188Os = 1.31 ± 0.24. Sulphides from LK113 have clear imposed diamond morphology and indicate diamond formation at 0.93 ± 0.36 Ga (2SD) with initial 187Os/188Os = 0.69 ± 0.44. The variation in the initial 187Os/188Os does not justify including these

  7. U-Pb and Rb-Sr isotopic systematics of fluids associated with mineralization of the Dartmoor granite, southwest England

    Science.gov (United States)

    Wayne, David M.; Miller, Martin F.; Scrivener, Richard C.; Banks, David A.

    1996-02-01

    Quartz veins from early hydrothermal mineralization within the 280 Ma Dartmoor granite contain abundant fluid inclusions, which were sampled using crush-leach techniques and analyzed for Rb, Sr, U, and Pb content and isotopic ratios. The present-day lead isotopic signature of some of the crushleach fluids is similar to that of granitic alkali feldspars from Dartmoor and other localities in southwest England, although some fluid samples contain a more radiogenic Pb component. The more radiogenic fluids fell into, or near, the granitic K-feldspar field upon correction of the present-day fluid Pb ratios for in situ U decay over ca. 280 Ma, but the lead isotope ratios of the less-radiogenic fluids became significantly lower than that of the granitic K-feldspars. The apparent overcorrection may be real, or may reflect either fluid mixing due to leaching of secondary fluid inclusions, differential leaching of U and Pb, the presence of an undetermined U-rich included phase (or fracture-filling) within the quartz, or a combination of the above. The variation of fluid U/Pb ratios also suggests some complications regarding either the selective retention of U and Pb on quartz surfaces, or the presence of submicroscopic U-rich inclusions. Therefore, we suggest that in situ decay corrections to lead isotopic data obtained using crush-leach techniques be applied with great caution. The fluid 87Rb/ 86Sr values vary little (1.40-1.74), as do their present-day strontium isotope signatures ( 87Rb/ 86Sr = 0.71814-0.71968). When corrected for in situ 87Rb decay over 280 Ma, the fluids contain significant excess radiogenic Sr (Sr i = 0.7118-0.7141), relative to the Dartmoor granite S i (=0.7101). If the Sr in the fluids is derived exclusively from the granite, or some granite-related source, and closedsystem evolution of the Rb-Sr isotopic system is assumed, the amount of excess 87Sr is a function of the time difference between Sr closure in the granite and Sr closure in the vein. Age

  8. Halogen and Cl isotopic systematics in Martian phosphates: Implications for the Cl cycle and surface halogen reservoirs on Mars

    Science.gov (United States)

    Bellucci, J. J.; Whitehouse, M. J.; John, T.; Nemchin, A. A.; Snape, J. F.; Bland, P. A.; Benedix, G. K.

    2017-01-01

    The Cl isotopic compositions and halogen (Cl, F, Br, and I) abundances in phosphates from eight Martian meteorites, spanning most rock types and ages currently available, have been measured in situ by Secondary Ion Mass Spectrometry (SIMS). Likewise, the distribution of halogens has been documented by x-ray mapping. Halogen concentrations range over several orders of magnitude up to some of the largest concentrations yet measured in Martian samples or on the Martian surface, and the inter-element ratios are highly variable. Similarly, Cl isotope compositions exhibit a larger range than all pristine terrestrial igneous rocks. Phosphates in ancient (>4 Ga) meteorites (orthopyroxenite ALH 84001 and breccia NWA 7533) have positive δ37Cl anomalies (+1.1 to + 2.5 ‰). These samples also exhibit explicit whole rock and grain scale evidence for hydrothermal or aqueous activity. In contrast, the phosphates in the younger basaltic Shergottite meteorites (Phosphates with the largest negative δ37Cl anomalies display zonation in which the rims of the grains are enriched in all halogens and have significantly more negative δ37Cl anomalies suggestive of interaction with the surface of Mars during the latest stages of basalt crystallization. The phosphates with no textural, major element, or halogen enrichment evidence for mixing with this surface reservoir have an average δ37Cl of - 0.6 ‰, supporting a similar initial Cl isotope composition for Mars, the Earth, and the Moon. Oxidation and reduction of chlorine are the only processes known to strongly fractionate Cl isotopes, both positively and negatively, and perchlorate has been detected in weight percent concentrations on the Martian surface. The age range and obvious mixing history of the phosphates studied here suggest perchlorate formation and halogen cycling via brines, which have been documented on the Martian surface, has been active throughout Martian history.

  9. Sm-Nd and Initial Sr-87/Sr-86 Isotopic Systematics of Asuka 881394 and Cumulate Eucrites Yamato 980318/433 Compared

    Science.gov (United States)

    Nyquist, L. E.; Shih, C-Y; Young, Y. D.; Takeda, H.

    2011-01-01

    The Asuka 881394 achondrite contains fossil Al-26 and Mn-53 and has a Pb-206/Pb-207 age of 4566.5 +/- 0.2 Ma, the oldest for an achondrite. Recent re-investigation of A881394 yielded revised initial Sm-146/Sm-144 = (9.1 +/- 1.4) x 10(exp -3), a Sm-147-Nd-143 age of 4525 +/- 58 Ma, a Rb-87-Sr-87 age of 4490 +/- 130 Ma, and initial Sr-87/Sr-86 = 0.698991 +/- 19, respectively. The relatively large uncertainties in the Sm-Nd and Rb-Sr ages are due to disturbances of the isotopic systematics of tridymite and other minor phases. A preliminary value for the Sm-147-Nd-143 age of the Yamato 980318 cumulate eucrite of 4560 +/- 150 Ma was refined in later work to 4567 +/- 24 Ma as reported orally at LPSC 35. Similarly, a preliminary value for Sm-146/Sm-144 = (7.7 +/- 1.2) x 10 (exp -3) was refined to (6.0 +/- 0.3) x 10(exp -3). For Yamato 980433, a Sm-147-Nd-143 age of 4542 +/-42 Ma and Sm-146/Sm-144 = (5.7 +/- 0.5) x 10(exp -3) has been reported. Because these two cumulate eucrites are paired, we consider them to represent one igneous rock and present their combined isotopic data here.

  10. Strontium isotope systematics of mixing groundwater and oil-field brine at Goose Lake in northeastern Montana, USA

    Science.gov (United States)

    Peterman, Zell E.; Thamke, Joanna N.; Futa, Kiyoto; Preston, Todd

    2012-01-01

    Groundwater, surface water, and soil in the Goose Lake oil field in northeastern Montana have been affected by Cl−-rich oil-field brines during long-term petroleum production. Ongoing multidisciplinary geochemical and geophysical studies have identified the degree and local extent of interaction between brine and groundwater. Fourteen samples representing groundwater, surface water, and brine were collected for Sr isotope analyses to evaluate the usefulness of 87Sr/86Sr in detecting small amounts of brine. Differences in Sr concentrations and 87Sr/86Sr are optimal at this site for the experiment. Strontium concentrations range from 0.13 to 36.9 mg/L, and corresponding 87Sr/86Sr values range from 0.71097 to 0.70828. The local brine has 168 mg/L Sr and a 87Sr/86Sr value of 0.70802. Mixing relationships are evident in the data set and illustrate the sensitivity of Sr in detecting small amounts of brine in groundwater. The location of data points on a Sr isotope-concentration plot is readily explained by an evaporation-mixing model. The model is supported by the variation in concentrations of most of the other solutes.

  11. Simultaneous spectroscopy of $\\gamma$- rays and conversion electrons: Systematic study of EO transitions and intruder states in close vicinity of mid-shell point in odd-Au isotopes

    CERN Multimedia

    Venhart, M; Grant, A F; Petrik, K

    This proposal focuses on detailed systematic studies of the $\\beta$ /EC-decays of $^{179,181,183,185}$Hg leading to excited states in the neutron-deficient Au isotopes in the vicinity of the N=104 midshell. $\\gamma$-ray, X-ray and conversion electron de-excitations of odd-A Au isotopes will be studied simultaneously. These studies will address important structural questions such as the excitation energies of coexisting states, properties of multiple intruder states (i.e. intruder particles coupled to intruder cores) and mixing of coexisting structures. The unique combination of Hg beam purity and yields make ISOLDE a unique facility for these experiments.

  12. A systematic study of proton, alpha and cluster decays in Rhenium isotopes using the effective liquid drop model

    Science.gov (United States)

    Joseph, Deepthy Maria; Ashok, Nithu; Joseph, Antony

    2016-01-01

    Employing the effective liquid drop model (ELDM), half-lives of proton and alpha decays and probable cluster decays are computed and analyzed for different proton-rich and neutron-rich isotopes of Rhenium. The investigation fortifies the phenomenon of cluster radioactivity (CR) in rare earth nuclei and also affirms the pivotal role played by neutron magicity in cluster decays. ELDM data is compared with that of universal decay law (UDL) model and found to be more efficient than the latter one. Apparently, cluster emissions slacken as the neutron number of daughter nucleus goes up and the linear nature of Geiger-Nuttall (G-N) plots stays unaltered even if the surface potential is incorporated.

  13. Oxygen and sulfur isotope systematics of sulfate produced during abiotic and bacterial oxidation of sphalerite and elemental sulfur

    Science.gov (United States)

    Balci, N.; Mayer, B.; Shanks, Wayne C.; Mandernack, K.W.

    2012-01-01

    Studies of metal sulfide oxidation in acid mine drainage (AMD) systems have primarily focused on pyrite oxidation, although acid soluble sulfides (e.g., ZnS) are predominantly responsible for the release of toxic metals. We conducted a series of biological and abiotic laboratory oxidation experiments with pure and Fe-bearing sphalerite (ZnS & Zn 0.88Fe 0.12S), respectively, in order to better understand the effects of sulfide mineralogy and associated biogeochemical controls of oxidation on the resultant ?? 34S and ?? 18O values of the sulfate produced. The minerals were incubated in the presence and absence of Acidithiobacillus ferrooxidans at an initial solution pH of 3 and with water of varying ?? 18O values to determine the relative contributions of H 2O-derived and O 2-derived oxygen in the newly formed sulfate. Experiments were conducted under aerobic and anaerobic conditions using O 2 and Fe(III) aq as the oxidants, respectively. Aerobic incubations with A. ferrooxidans, and S o as the sole energy source were also conducted. The ??34SSO4 values from both the biological and abiotic oxidation of ZnS and ZnS Fe by Fe(III) aq produced sulfur isotope fractionations (??34SSO4-ZnS) of up to -2.6???, suggesting the accumulation of sulfur intermediates during incomplete oxidation of the sulfide. No significant sulfur isotope fractionation was observed from any of the aerobic experiments. Negative sulfur isotope enrichment factors (??34SSO4-ZnS) in AMD systems could reflect anaerobic, rather than aerobic pathways of oxidation. During the biological and abiotic oxidation of ZnS and ZnS Fe by Fe(III) aq all of the sulfate oxygen was derived from water, with measured ?? 18OSO 4-H 2O values of 8.2??0.2??? and 7.5??0.1???, respectively. Also, during the aerobic oxidation of ZnS Fe and S o by A. ferrooxidans, all of the sulfate oxygen was derived from water with similar measured ?? 18OSO 4-H 2O values of 8.1??0.1??? and 8.3??0.3???, respectively. During biological oxidation

  14. Systematic regional variations in diamond carbon isotopic composition and inclusion chemistry beneath the Orapa kimberlite cluster, in Botswana

    Science.gov (United States)

    Deines, Peter; Stachel, Thomas; Harris, Jeff W.

    2009-11-01

    The carbon isotopic composition, nitrogen content and aggregation state of 95 inclusion bearing diamonds, collected from the production of Damtshaa kimberlites, were investigated. The Damtshaa kimberlites belong to the group of southern African kimberlites showing 12C enrichment in eclogitic compared to peridotitic diamonds. The results were compared with similar studies of the nearby Orapa and Letlhakane kimberlites, providing the opportunity to examine variations in mantle composition on the kilometer scale. While Orapa, Letlhakane and Damtshaa diamonds may share some overall similarities in their δ 13C distribution, there are significant differences among them. These differences support the concept that diamonds from different kimberlite pipes have distinctive features in their δ 13C distribution and that this is true for kimberlite occurrences which are spatially separated by only a few tens of km. Compared to Orapa, peridotitic garnet inclusions from Damtshaa and Letlhakane are derived, in part, from highly depleted dunitic-harzburgitic reservoirs extending to greater depth. In all three kimberlites diamonds with eclogitic garnet inclusions displaying comparatively low Al 2O 3/Cr 2O 3 ratios, characteristic for mantle compositions, show a wide range in carbon isotopic composition from about - 4 to - 18 ‰ vs. PDB. The observed relationship between δ 13C and Al 2O 3/Cr 2O 3 ratios indicates the presence of 13C depleted mantle sources that cannot be explained by subduction. Estimates of possible pressure/temperature conditions, based on the Fe/Mg distribution coefficients of coexisting eclogitic garnets and clinopyroxenes and the Ca mole fraction in garnets, lead to the conclusion that beneath the Orapa, Letlhakane, and Damtshaa kimberlites there is a mantle zone depleted in 13C, approximately 20-30 km thick and extending over an area of at least 200 km 2.

  15. Search for a meteoritic component in impact-melt rocks from the Lonar crater, India - Evidence from osmium isotope systematics

    Science.gov (United States)

    Schulz, T.; Luguet, A.; Koeberl, C.

    2013-12-01

    Introduction: The Lonar crater in western India (Maharashtra) is a bowl-shaped simple impact structure of 1830 m diameter and a depth of 120 m below the rim crest. The crater formed 0.656 × 0.081 Ma ago on the 65 Ma old basaltic lava flows of the Deccan Traps (Jourdan et al. 2010) and is one of the few terrestrial impact structures to have formed in basaltic host-rocks. In the absence of actual meteorite fragments, the impact origin of this structure was supported by the identification of a variety of shock metamorphic features (e.g. Fredriksson et al. 1973). However, clear indications of an extraterrestrial component in impactites based on geochemical studies are absent or remained ambiguous so far (e.g. Osae et al. 2005). As the Os isotope tool has the potential to provide firm constraints on the presence or absence of even very small (g. Koeberl et al. 2002), we conduct a detailed Os isotope study of a variety of unshocked host-basalts (target rocks) and impactites (impact-melt rocks) from the Lonar crater. Samples and Method: All samples analyzed in this study were collected in 2000 and 2001 and were geochemically characterized by Osae et al. (2005). Osmium (and additional PGE) analyses were performed on about 2 g whole rock powders, which were spiked with a mixed 190Os,185Re,191Ir,194Pt tracer, and digested via high pressure Asher using inverse aqua regia. Osmium solvent extraction and microdistillation were performed as described by Cohen and Waters (1996). Osmium isotopic compositions were measured using a TRITON N-TIMS at the Department of Lithospheric Research in Vienna. Results and Discussion: Osmium data on seven target and nine impact melt rocks reveal 187Os/188Os ratios ranging from ~0.38 to ~2.23 for the target rocks and from ~0.22 to ~0.59 for the nine analyzed impact melt rocks, whereas Os concentrations range from ~7.1 to ~31.6 ppt and ~7.2 to ~134 ppt, respectively. Although in the typical range for basalts from the Deccan Traps (e.g., Allegre et

  16. U-Pb isotopic systematics of zircons from prograde and retrograde transition zones in high-grade orthogneisses, Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    Baur, N.; Liew, T.C.; Todt, W.; Hofmann, A.W. (Max-Planck-Institut fuer Chemie, Mainz (West Germany)); Kroener, A. (Univ. Mainz (West Germany)); Williams, I.S. (Australian National Univ., Canberra (Australia))

    1991-07-01

    The authors present U-Pb zircon isotopic data from locally restricted prograde (arrested in situ charnockitization) and retrograde metamorphic transition zones, which are well exposed in Proterozoic orthogneisses tectonically interbanded with granulite facies supracrustal rocks of the Highland Group in Sri Lanka. These granitoid rocks yield apparent ages of 1942 {plus minus} 22 Ma, {approximately} 770 Ma, {approximately} 660 Ma, and {approximately} 560 Ma. All samples show severe Pb-loss some 550-560 Ma ago. The main phase of granulite-formation could not be dated unambiguously but is bracketed between {approximately} 660 Ma and {approximately} 550 Ma. The pervasive Pb-loss event around 550-560 Ma reflects the end of this period of high-grade metamorphism and was associated with widespread igneous activity and retrogression. This is constrained by the 550 {plus minus} 3 Ma intrusion age for a post-tectonic granite. They relate this late phase of thermal activity to crustal uplift of the Sri Lankan granulites. This data unambiguously prove the high-grade history of the Sri Lanka gneisses to be a late Precambrian event that may be related to the Pan-African evolution along the eastern part of Africa.

  17. Oxygen isotope systematics in the aragonite-CO2-H2O-NaCl system up to 0.7 mol/kg ionic strength at 25 °C

    Science.gov (United States)

    Kim, Sang-Tae; Gebbinck, Christa Klein; Mucci, Alfonso; Coplen, Tyler B.

    2014-01-01

    To investigate the oxygen isotope systematics in the aragonite-CO2-H2O-NaCl system, witherite (BaCO3) was precipitated quasi-instantaneously and quantitatively from Na-Cl-Ba-CO2 solutions of seawater-like ionic strength (I = 0.7 mol/kg) at two pH values (~7.9 and ~10.6) at 25 °C. The oxygen isotope composition of the witherite and the dissolved inorganic carbon speciation in the starting solution were used to estimate the oxygen isotope fractionations between HCO3¯ and H2O as well as between CO3 2 and H2O. Given the analytical error on the oxygen isotope composition of the witherite and uncertainties of the parent solution pH and speciation, oxygen isotope fractionation between NaHCO3° and HCO3¯, as well as between NaCO3¯ and CO3 2, is negligible under the experimental conditions investigated. The influence of dissolved NaCl concentration on the oxygen isotope fractionation in the aragonite-CO2-H2O-NaCl system also was investigated at 25 °C. Aragonite was precipitated from Na-Cl-Ca-Mg-(B)-CO2 solutions of seawater-like ionic strength using passive CO2 degassing or constant addition methods. Based upon our new experimental observations and published experimental data from lower ionic strength solutions by Kim et al. (2007b), the equilibrium aragonite-water oxygen isotope fractionation factor is independent of the ionic strength of the parent solution up to 0.7 mol/kg. Hence, our study also suggests that the aragonite precipitation mechanism is not affected by the presence of sodium and chloride ions in the parent solution over the range of concentrations investigated.

  18. Termination of a continent-margin upwelling system at the Permian-Triassic boundary (Opal Creek, Alberta, Canada)

    Science.gov (United States)

    Schoepfer, Shane D.; Henderson, Charles M.; Garrison, Geoffrey H.; Foriel, Julien; Ward, Peter D.; Selby, David; Hower, James C.; Algeo, Thomas J.; Shen, Yanan

    2013-06-01

    Models of mass extinctions caused by greenhouse warming depend on the ability of warming to affect the oxygenation of the ocean, either through slowing circulation or changes in biological productivity and the organic carbon budget. Opal Creek, Alberta, Canada is a biostratigraphically continuous Permian-Triassic Boundary (PTB) section deposited in deep water on an outer shelf setting in the vast and understudied Panthalassic Ocean, along the western margin of Pangaea. The latest-Permian extinction is here represented as the disappearance of the previously dominant benthic fauna (siliceous sponges). On the basis of nitrogen and reduced sulfur isotopes as well as productivity-sensitive trace elements, the Middle Permian at Opal Creek is interpreted as a highly productive coastal upwelling zone where vigorous denitrification and sulfate reduction occurred in a mid-water oxygen minimum. Similar conditions appear to have continued into the latest Permian until the onset of a euxinic episode represented by a discrete pyrite bed and several trace element indicators of high productivity. This euxinic pulse is followed by the extinction of benthic fauna and a shift in nitrogen and sulfur isotopes to more normal marine values, suggesting the cessation of coastal upwelling and the consequent weakening of the mid-water oxygen minimum. The Lower Triassic appears to be a dysoxic, relatively unproductive environment with a bottom water oxygen minimum. Rhenium-osmium isotope systematics show a minimum of radiogenic Os near the main extinction event, which may be due to volcanic input, and increasingly radiogenic values approaching the PTB, possibly due to increased continental erosion. The Opal Creek system demonstrates that, while the biogeochemical crisis in the latest Permian was capable of impacting the coastal upwelling modality of ocean circulation, a transient increase in productivity likely drove the system toward euxinia and, ultimately, extinction.

  19. The estuarine chemistry and isotope systematics of 234,238U in the Amazon and Fly Rivers

    Science.gov (United States)

    Swarzenski, P.; Campbell, P.; Porcelli, D.; McKee, B.

    2004-01-01

    Natural concentrations of 238U and ??234U values were determined in estuarine surface waters and pore waters of the Amazon and Fly (Papua New Guinea) Rivers to investigate U transport phenomena across river-dominated land-sea margins. Discharge from large, tropical rivers is a major source of dissolved and solid materials transported to the oceans, and are important in defining not only oceanic mass budgets, but also terrestrial weathering rates. On the Amazon shelf, salinity-property plots of dissolved organic carbon, pH and total suspended matter revealed two vastly contrasting water masses that were energetically mixed. In this mixing zone, the distribution of uranium was highly non-conservative and exhibited extensive removal from the water column. Uranium removal was most pronounced within a salinity range of 0-16.6, and likely the result of scavenging and flocculation reactions with inorganic (i.e., Fe/Mn oxides) and organic colloids/particles. Removal of uranium may also be closely coupled to exchange and resuspension processes at the sediment/water interface. An inner-shelf pore water profile indicated the following diagenetic processes: extensive (???1 m) zones of Fe(III) - and, to a lesser degree, Mn(IV) - reduction in the absence of significant S(II) concentrations appeared to facilitate the formation of various authigenic minerals (e.g., siderite, rhodocrosite and uraninite). The pore water dissolved 238U profile co-varied closely with Mn(II). Isotopic variations as evidenced in ??234U pore waters values from this site revealed information on the origin and history of particulate uranium. Only after a depth of about 1 m did the ??234U value approach unity (secular equilibrium), denoting a residual lattice bound uranium complex that is likely an upper-drainage basin weathering product. This suggests that the enriched ??234U values represent a riverine surface complexation product that is actively involved in Mn-Fe diagenetic cycles and surface

  20. APPLICATION OF O-H-B-Sr ISOTOPE SYSTEMATICS TO THE EXPLORATION OF SALINIZATION AND FLUSHING IN COASTAL AQUIFERS : PRELIMINARY DATA FROM THE PIALASSA BAIONA ECOSYSTEM (ADRIATIC SEA

    Directory of Open Access Journals (Sweden)

    Riccardo Petrini

    2009-07-01

    Full Text Available O, H, B and Sr isotopes were identified from surface-waters, ground-waters and waters percolating in soils at the Pialassa Baiona lagoon and nearby inland areas. The preliminary data demonstrate the occurrence of both conservative mixtures between seawater and freshwaters and cation exchange at the salt/fresh water interface during the intrusion. The O and H isotopes indicate that the freshwater component in the binary mixing had the isotopic features of the rainwater from Apennine catchments. Coupled O-H-B isotopes also show that the major contribution of the moving seawater was confined to the deeper aquifers and some of the soil waters. The Sr isotopes highlight the role of cation exchanges when seawater flushes freshwater aquifers, and allow the recognition of the different components of the solute. Deviations from these processes as revealed by B isotopes are interpreted as the evidence of possible anthropogenic inputs.

  1. Petrogenesis of Tertiary continental intra-plate lavas between Siebengebirge and Westerwald, Germany: Constraints from trace element systematics and Nd, Sr and Pb isotopes

    Science.gov (United States)

    Schubert, S.; Jung, S.; Pfänder, J. A.; Hauff, F.; Garbe-Schönberg, D.

    2015-10-01

    New 39Ar/40Ar ages and major- and trace-element and radiogenic isotope data are presented for basanites and alkali basalts from the transition area between the Westerwald and Siebengebirge volcanic fields (Germany) that belongs to the Central European Volcanic Province (CEVP). The 39Ar/40Ar ages indicate ages of c. 24 and c. 5 Ma which are fully compatible with previous K/Ar ages indicating that the evolution of this volcanic field belongs to the Westerwald area (28-22 Ma and 5 Ma) rather than to the Siebengebirge area (26-23 Ma). Based on the occurrence of > 30 isolated volcanic plugs with a simple igneous history, this volcanic field can be viewed as a monogenetic volcanic field. Compositions of some basanites are primitive, whereas others and the alkali basalts show decreasing Cr and Ni contents and CaO/Al2O3 ratios. However, increasing TiO2, Al2O3 and incompatible elements (Sr, Zr, Y, Hf, Ta) concentrations with decreasing MgO indicating fractionation of mainly olivine with minor amounts of clinopyroxene and spinel can be noticed. Rare earth element systematics suggest that most of the alkaline rocks are generated by different degrees of melting (5%-10%) of a garnet-bearing peridotite containing some residual amphibole. Negative anomalies of Rb and K in primitive mantle-normalized diagrams and a lack of Ba/Rb fractionation suggest that amphibole was the major OH-bearing mineral phase in the mantle. The alkaline rocks have a restricted range in 87Sr/86Sr and 143Nd/144Nd ratios ranging from 0.7033 to 0.7044 and from 0.51275 to 0.51285, respectively. Lead isotope compositions (206Pb/204Pb: 19.21-19.65; 207Pb/204Pb: 15.62-15.67; 208Pb/204Pb: 39.10-39.46) of the alkaline rocks are within the range of most OIB in which the higher values approach the composition of the European Asthenospheric Reservoir (EAR). The correlation between Sr and Nd isotopes and trace element constraints (Ce/Pb; Nb/U) indicates that for some samples interaction with crustal rocks during

  2. Constraining the role of iron in environmental nitrogen transformations. Dual stable isotope systematics of abiotic NO2- reduction by Fe(II) and its production of N2O

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, David [Harvard Univ., Cambridge, MA (United States); Wankel, Scott David [Woods Hole Oceanographic Inst., MA (United States); Buchwald, Carolyn [Woods Hole Oceanographic Inst., MA (United States); Hansel, Colleen [Woods Hole Oceanographic Inst., MA (United States)

    2015-09-16

    Redox reactions involving nitrogen and iron have been shown to have important implications for mobilization of priority contaminants. Thus, an understanding of the linkages between their biogeochemical cycling is critical for predicting subsurface mobilization of radionuclides such as uranium. Despite mounting evidence for biogeochemical interactions between iron and nitrogen, our understanding of their environmental importance remains limited. Here we present an investigation of abiotic nitrite (NO2-) reduction by Fe(II) or ‘chemodenitrification,’ and its relevance to the production of nitrous oxide (N2O), specifically focusing on dual (N and O) isotope systematics under a variety of environmentally relevant conditions. We observe a range of kinetic isotope effects that are regulated by reaction rates, with faster rates at higher pH (~8), higher concentrations of Fe(II) and in the presence of mineral surfaces. A clear non-linear relationship between rate constant and kinetic isotope effects of NO2- reduction was evident (with larger isotope effects at slower rates) and is interpreted as reflecting the dynamics of Fe(II)-N reaction intermediates. N and O isotopic composition of product N2O also suggests a complex network of parallel and/or competing pathways. Our findings suggest that NO2- reduction by Fe(II) may represent an important abiotic source of environmental N2O, especially in iron-rich environments experiencing dynamic redox variations. This study provides a multi-compound, multi-isotope framework for evaluating the environmental occurrence of abiotic NO2- reduction and N2O formation, helping future studies constrain the relative roles of abiotic and biological N2O production pathways.

  3. Chlorine isotopes potential as geo-chemical tracers

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Pradhan, U.K.; Banerjee, R.

    The potential of chlorine isotopes as tracers of geo-chemical processes of earth and the oceans is highlighted based on systematic studies carried out in understanding the chlorine isotope fractionation mechanism, its constancy in seawater and its...

  4. PETROCHEMISTRY, Pb ISOTOPE SYSTEMATICS, AND ...

    African Journals Online (AJOL)

    ... to 1.35, respectively) and normal Pb content (30-47 ppm) show that the common Pb component of these gneisses have not been contaminated with radiogenic Pb. Common Pb model ages obtained for the granite gneisses indicate that they were probably emplaced around 2640 Ma and deformed during the Proterozoic.

  5. Isotope separation

    Science.gov (United States)

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  6. Evaluating crustal contributions to enriched shergottites from the petrology, trace elements, and Rb-Sr and Sm-Nd isotope systematics of Northwest Africa 856

    Science.gov (United States)

    Ferdous, J.; Brandon, A. D.; Peslier, A. H.; Pirotte, Z.

    2017-08-01

    The origin of the incompatible trace element (ITE) characteristics of enriched shergottites has been critical for examining two contradicting scenarios to explain how these Martian meteorites form. The first scenario is that it reflects ITE enrichment in an early-formed mantle reservoir whereas the second scenario attributes it to assimilation of ancient Martian crust (∼4-4.5 Ga) by ITE-depleted magmas. Strongly differentiated shergottite magmas may yield added constraints for determining which scenario can best explain this signature in enriched shergottites. The meteorite Northwest Africa (NWA) 856 is a basaltic shergottite that, unlike many enriched shergottites, lacks olivine and has undergone extensive differentiation from more primitive parent magma. In similarity to other basaltic shergottites, NWA 856 is comprised primarily of compositionally zoned clinopyroxenes (45% pigeonite and 23% augite), maskelynite (23%) and accessory minerals such as ulvöspinel, merrillite, Cl-apatite, ilmenite, pyrrhotite, baddeleyite and silica polymorph. The CI-chondrite normalized rare earth element (REE) abundance patterns for its maskelynite, phosphates, and its whole rock are flat with corresponding light-REE depletions in clinopyroxenes. The 87Rb-87Sr and 147Sm-143Nd internal isochron ages are 162 ± 14 (all errors are ±2σ) Ma and 162.7 ± 5.5 Ma, respectively, with an initial εNdI = -6.6 ± 0.2. The Rb-Sr isotope systematics are affected by terrestrial alteration resulting in larger scatter and a less precise internal isochron age. The whole rock composition is used in MELTS simulations to model equilibrium and fractional crystallization sequences to compare with the crystallization sequence from textural observations and to the mineral compositions. These models constrain the depth of initial crystallization to a pressure range of 0.4-0.5 GPa (equivalent to 34-42 km) in anhydrous conditions at the Fayalite-Magnetite-Quartz buffer, and consistently reproduce the

  7. Calcium isotope systematics in small upland catchments affected by spruce dieback in the period of extreme acid rain (1970-1990)

    Science.gov (United States)

    Novak, Martin; Farkas, Juraj; Holmden, Chris; Hruska, Jakub; Curik, Jan; Stepanova, Marketa; Prechova, Eva; Veselovsky, Frantisek; Komarek, Arnost

    2017-04-01

    Recently, new isotope tools have become available to study the behavior of nutrients in stressed ecosystems. In this study, we focus on changes in the abundance ratio of calcium (Ca) isotopes accompanying biogeochemical processes in small forested catchments. We monitored del44Ca values in ecosystem pools and fluxes in four upland sites situated in the Czech Republic, Central Europe. A heavily acidified site in the Eagle Mts. (northern Czech Republic) experienced 13 times higher atmospheric Ca inputs, compared to the other three sites, which were less affected by forest decline. Industrial dust was responsible for the elevated Ca input. Del44Ca values of individual poos/fluxes were used to identify Ca sources for the bioavailable Ca soil reservoir and for runoff. The bedrock of the study sites differed (leucogranite, orthogneiss vs. serpentinite and amphibolite). Across the sites, mean del44Ca values increased in the order: spruce bark Plant preferentially took up isotopically light Ca, while residual isotopically heavy Ca was sorbed to soil particles or exported via runoff. Even at sites with a low del44Ca values of bedrock, runoff had a high del44Ca value. At the base-poor site, most runoff came from atmospheric deposition and residual Ca following plant uptake. It appeared that bedrock weathering did not supply enough Ca to replenish the bioavailable Ca pool in the soil. Currently, we are analyzing Ca isotope composition of individual rock-forming minerals to better assess the effect of different weathering rates of minerals with low/high radiogenic 40Ca contents on runoff del44Ca.

  8. Speculations on nature and extent of Archean basement in Labrador as indicated by SR, ND and PB isotopic systematics of proterozoic intrusives

    Science.gov (United States)

    Ashwal, L. D.; Wooden, J. L.; Emslie, R. F.

    1986-01-01

    The Sm-Nd and Rb-Sr isotopic compositions of mid to late Proterozoic (approximately 1.6 to 1.1 Ga) massif-type anorthosites and mafic intrusives in the eastern Canadian shield are correlated with geographic location. Complexes in the Grenville province have positive epsilon sub Nd values and initial Sr-87/Sr-86 (I sub Sr) generally less than 0.703, suggesting derivation from depleted mantle. In Labrador, similar complexes close to or northwest of a line roughly corresponding to the Grenville Front have negative epsilon sub Nd values and I sub Sr 0.703. This contrast was intrepreted as reflecting either enriched mantle under the Nain Province, or contamination of the Nain intrusives with older crustal components. Lead isotopic compositions, however, favor the latter. The possibility of using these Proterozoic intrusives as tracers to characterize the nature and extent of older basement types in Labrador is discussed.

  9. Leatherback Isotopes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC is currently working on a project identifying global marine isotopes using leatherback turtles (Dermochelys coriacea) as the indicator species. We currently...

  10. Isotope Identification

    Energy Technology Data Exchange (ETDEWEB)

    Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-18

    The objective of this training modules is to examine the process of using gamma spectroscopy for radionuclide identification; apply pattern recognition to gamma spectra; identify methods of verifying energy calibration; and discuss potential causes of isotope misidentification.

  11. PGE, Re-Os, and Mo isotope systematics in Archean and early Proterozoic sedimentary systems as proxies for redox conditions of the early Earth

    Science.gov (United States)

    Siebert, C.; Kramers, J. D.; Meisel, Th.; Morel, Ph.; Nägler, Th. F.

    2005-04-01

    Re-Os data and PGE concentrations as well as Mo concentrations and isotope data are reported for suites of fine clastic sediments and black shales from the Barberton Greenstone Belt, South Africa (Fig Tree and Moodies Groups, 3.25-3.15 Ga), the Belingwe Greenstone Belt, Zimbabwe (Manjeri Formation, ca. 2.7 Ga) and shales from the Witwatersrand, Ventersdorp and Transvaal Supergroups, South Africa ranging from 2.95 to 2.2 Ga. Moderately oxidizing conditions are required to mobilize Re and Mo in the environment, Mo fractionation only occurs in solution, and these parameters thus have potential use as paleoredox proxies for the early Earth. PGE + Re abundance patterns of Barberton Greenstone Belt sediments are uniform and very similar in shape to those of komatiites. This indicates (1) that the PGE came from a source of predominantly ultramafic composition and, (2) that PGE were transported and deposited essentially in particulate form. Sediments from the younger Belingwe Greenstone Belt show more fractionated PGE + Re patterns and have Re/Os ratios 10 to 100× higher than those of Barberton sediments. Their PGE abundance patterns and Re/Os ratios are intermediate between those of the mid-Archean shales and Neoproterozoic to Recent black shales. They reflect scavenging of Re from solution in the sedimentary environment. δ 98/95Mo values of black shales of all ages correlate with their concentrations. The Barberton Greenstone Belt samples have ˜1-3 ppm Mo, similar to a granitoid-basaltic source. This Mo has δ 98/95Mo between -1.9 and -2.4‰ relative to present day mean ocean water molybdenum, MOMO and is thus not isotopically fractionated relative to such a source. Similar to the PGE this indicates transport in solid form. Sediments from the Belingwe Greenstone Belt show in part enhanced Mo concentrations (up to 6 ppm) and Mo isotope fractionation (δ 98/95Mo up to -1.4‰ relative to MOMO). The combined PGE + Re and Mo data show mainly reducing conditions in the

  12. The reliability of ∼2.9 Ga old Witwatersrand banded iron formations (South Africa) as archives for Mesoarchean seawater: Evidence from REE and Nd isotope systematics

    Science.gov (United States)

    Viehmann, Sebastian; Bau, Michael; Smith, Albertus J. B.; Beukes, Nicolas J.; Dantas, Elton L.; Bühn, Bernhard

    2015-11-01

    Pure marine chemical sediments, such as (Banded) Iron Formations, (B)IFs, are archives of geochemical proxies for the composition of Precambrian seawater and may provide information about the ancient hydrosphere-atmosphere system. We here present rare earths and yttrium (REY) and high precision Sm-Nd isotope data of ∼2.90 Ga old Superior-type BIFs from the Witwatersrand Supergroup, South Africa, and compare those with data for near-contemporaneous BIFs from the correlative Pongola Supergroup (Superior-type BIF) and from the Pietersburg Greenstone Belt (Algoma-type IF), respectively. All Witwatersrand samples studied display the typical general REY distribution of Archean seawater, but their REY anomalies are less pronounced and their immobile element concentrations are higher than those of other pure (B)IFs. These observations indicate the presence of significant amounts of detrital aluminosilicates in the Witwatersrand BIFs and question the reliability of the Contorted Bed and Water Tower BIFs (Parktown Formation, West Rand Group) as archives of Mesoarchean seawater. Significant post-depositional alteration of the REY budget and the Sm-Nd isotope system is not observed. The Nd isotopic compositions of the purest BIF samples, i.e. the most reliable archives for Witwatersrand seawater, show initial εNd values between -3.95 and -2.25. This range is more negative than what is observed in ambient shales, indicating a decoupling of suspended and dissolved loads in the "near-shore" Witwatersrand Basin seawater. However, εNd range overlaps with that of the correlative Pongola BIF (Alexander et al., 2008). The deeper-water Algoma-type Pietersburg BIF shows more positive (i.e. more mantle-like) εNd2.9Ga values, supporting the hypothesis that a significant amount of its REY inventory was derived from black smoker-style, high-temperature hydrothermal fluids that had altered seafloor basalts. In marked contrast, the dissolved REY budgets (including the Nd isotopic

  13. ISOTOPE SEPARATORS

    Science.gov (United States)

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  14. Sm-Nd and Rb-Sr Isotopic Systematics of a Heavily Shocked Martian Meteorite Tissint and Petrogenesis of Depleted Shergottites

    Science.gov (United States)

    Shih, C.-Y.; Nyquist, L. E.; Park, J.; Agee, Carl B.

    2014-01-01

    Tissint is a very fresh Martian meteorite that fell near the town of Tissint in Morocco on July 18, 2011. It contains abundant olivine megacrysts (23%) in a fine-grained matrix of pyroxene (55%), maskelynitized plagioclase (15%), opaques (4%) and melt pockets (3%) and is petrographically similar to lithologies A and C of picritic shergottite EETA 79001 [1,2]. The presence of 2 types of shock-induced glasses and all 7 high-pressure mineral phases that were ever found in melt pockets of Martian meteorites suggests it underwent an intensive shock metamorphism of 25 GPa and 2000 C localized in melt pockets [2]. Mineral textures suggest that olivines, pyroxenes and plagioclases probably did not experience such hightemperature. Earlier determinations of its age yielded 596+/-23 Ma [3] and 616+/-67 Ma [4], respectively, for the Sm-Nd system and 583+/-86 Ma for the Lu-Hf system [4], in agreement with the 575+/-18 Ma age of the oldest olivine-phyric depleted shergottite Dho 019 [5]. However, the exposure ages of Tissint (1 Ma [1, 6, 7]) and Dho 019 (20 Ma [8]) are very different requiring two separate ejection events. These previously determined Sm-Nd and Lu-Hf ages are older than the Ar-Ar maskelynite plateau age of 524+/-15 Ma [9], reversing the pattern usually observed for Martian meteorites. In order to clarify these age issues and place models for Tissint's petrogenesis on a firm basis, we present new Rb-Sr and Sm- Nd isotopic results for Tissint, and discuss (a) the shock effects on them and the Ar-Ar chronometer, (b) correlation of the determined ages with those of other depleted shergottites, and (c) the petrogenesis of depleted shergottites. Since the meteorite is a recent fall, terrestrial contamination is expected to be minimal, but, the strong shock metamorphism might be expected to compromise the equilibrium of the isotopic systems.

  15. Sm-Nd and Sr isotope systematics of scheelite from the giant Au(-W) deposit Muruntau (Uzbekistan): implications for the age and sources of Au mineralization

    Science.gov (United States)

    Kempe, U.; Belyatsky, B.; Krymsky, R.; Kremenetsky, A.; Ivanov, P.

    2001-08-01

    The application of the Sm-Nd isotope system of scheelite to dating of low-sulfide, quartz-vein hosted Au mineralization is still under discussion. In the present work, new Sm-Nd and Rb-Sr data for scheelite from the giant Muruntau/Myutenbai Au deposit (Kyzylkum, Western Uzbekistan) are discussed. Based on the geological relationship, mineralogical properties, and trace element characteristics, two types of scheelite can be distinguished within the deposit. The first one is represented by early bluish luminescent and weakly coloured scheelite (generation 1) found within strongly deformed flat quartz veins. The apparent isochron defined by this scheelite (351±22 Ma) is interpreted as a mixing line. Typically brownish to orange and yellowish luminescent scheelite from steeply dipping veins (generation 2) defines a Sm-Nd isochron age of 279±18 Ma (ɛNd=-9.5±0.3; MSWD: 1.5). No evidence for mixing or disturbance by late alteration were found for these scheelites. This Sm-Nd isochron age agrees with the Rb-Sr and K-Ar age range for wall rock alteration in this deposit reported previously. The age of 280 Ma is interpreted to date the high-grade ore formation in the Muruntau deposit. There are currently no reliable age data available on the magmatic events in the Muruntau region. Probably, there is some overlap in time of the Hercynian gold deposition with the intrusion of lamprophyric dykes. The Nd and Sr isotopic signatures of scheelite define the wall rocks (mainly metasiltstones and metasandstones) as the most probable sources for these elements in scheelite.

  16. Stable isotope

    African Journals Online (AJOL)

    Results of the study suggest that there are two main carbon pathways for plankton and nekton in the Kariega estuary, carbon derived from the eelgrass and its associated epiphytes and carbon which has its origins in the salt marsh riparian vegetation and zooplankton. Keywords: stable isotope analysis; temperate estuary; ...

  17. Chromium isotope signature during continental crust subduction recorded in metamorphic rocks

    National Research Council Canada - National Science Library

    Shen, Ji; Liu, Jia; Qin, Liping; Wang, Shui‐Jiong; Li, Shuguang; Xia, Jiuxing; Ke, Shan; Yang, Jingsui

    2015-01-01

    The chromium isotope compositions of 27 metamorphic mafic rocks with varying metamorphic degrees from eastern China were systematically measured to investigate the Cr isotope behavior during continental crust subduction...

  18. Exploring the isotopic niche: isotopic variance, physiological incorporation, and the temporal dynamics of foraging

    Directory of Open Access Journals (Sweden)

    Justin Douglas Yeakel

    2016-01-01

    Full Text Available Consumer foraging behaviors are dynamic, changing in response to prey availability, seasonality, competition, and even the consumer's physiological state. The isotopic composition of a consumer is a product of these factors as well as the isotopic `landscape' of its prey, i.e. the isotopic mixing space. Stable isotope mixing models are used to back-calculate the most likely proportional contribution of a set of prey to a consumer's diet based on their respective isotopic distributions, however they are disconnected from ecological process. Here we build a mechanistic framework that links the ecological and physiological processes of an individual consumer to the isotopic distribution that describes its diet, and ultimately to the isotopic composition of its own tissues, defined as its `isotopic niche’. By coupling these processes, we systematically investigate under what conditions the isotopic niche of a consumer changes as a function of both the geometric properties of its mixing space and foraging strategies that may be static or dynamic over time. Results of our derivations reveal general insight into the conditions impacting isotopic niche width as a function of consumer specialization on prey, as well as the consumer's ability to transition between diets over time. We show analytically that moderate specialization on isotopically unique prey can serve to maximize a consumer's isotopic niche width, while temporally dynamic diets will tend to result in peak isotopic variance during dietary transitions. We demonstrate the relevance of our theoretical findings by examining a marine system composed of nine invertebrate species commonly consumed by sea otters. In general, our analytical framework highlights the complex interplay of mixing space geometry and consumer dietary behavior in driving expansion and contraction of the isotopic niche. Because this approach is established on ecological mechanism, it is well-suited for enhancing the

  19. Systematic sulfur stable isotope and fluid inclusion studies on veinlet groups in the Sarcheshmeh porphyry copper deposit: based on new data

    Directory of Open Access Journals (Sweden)

    Mohammad Maanijou

    2012-10-01

    Full Text Available Mineralization occurred by intrusion of granodioritic stock of middle Miocene in volcano–sedimenrary rocks in Sarcheshmeh of early Tertiary age. This research is based on samples of new drilled boreholes and benches of 2500m elevation. Based on mineralogy and crosscutting relationships, at least four groups of veinlets pertaining to four stages of mineralization were recognized. Sulfur isotope studies in the Sarcheshmeh porphyry copper deposit were conducted on pyrite, chalcopyrite, molybdenite and anhydrites of four groups of veinlets. The δ34S values in the sulfides and sulfates range from -2.2 to 1.27‰ and from 10.2 to 14.5 ‰, respectively. The average δ34S value in the sulfides is 1‰ and that for the sulfates is about 13‰. Considering these results, it can be concluded that the sulfides made up of a fluid that its sulfur has a magmatic origin. Also, fluid inclusions of different veinlet groups were studied, showing high temperature, high salinity and the occurrence of boiling in the mineralizing fluids. Moreover, these studies indicate presence of three types of fluids including magmatic, meteoritic and mixture of these two fluids in alteration and mineralizion processes.

  20. Multiconfiguration calculations of electronic isotope shift factors in Al I

    CERN Document Server

    Filippin, Livio; Ekman, Jörgen; Fritzsche, Stephan; Godefroid, Michel; Jönsson, Per

    2016-01-01

    The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of electronic isotope shift factors for a set of transitions between low-lying states in neutral aluminium. These electronic quantities together with observed isotope shifts between different pairs of isotopes provide the changes in mean-square charge radii of the atomic nuclei. Two computational approaches are adopted for the estimation of the mass- and field shift factors. Within these approaches, different models for electron correlation are explored in a systematic way to determine a reliable computational strategy and estimate theoretical uncertainties of the isotope shift factors.

  1. Stable isotope analysis in primatology: a critical review.

    Science.gov (United States)

    Sandberg, Paul A; Loudon, James E; Sponheimer, Matt

    2012-11-01

    Stable isotope analysis has become an important tool in ecology over the last 25 years. A wealth of ecological information is stored in animal tissues in the relative abundances of the stable isotopes of several elements, particularly carbon and nitrogen, because these isotopes navigate through ecological processes in predictable ways. Stable carbon and nitrogen isotopes have been measured in most primate taxonomic groups and have yielded information about dietary content, dietary variability, and habitat use. Stable isotopes have recently proven useful for addressing more fine-grained questions about niche dynamics and anthropogenic effects on feeding ecology. Here, we discuss stable carbon and nitrogen isotope systematics and critically review the published stable carbon and nitrogen isotope data for modern primates with a focus on the problems and prospects for future stable isotope applications in primatology. © 2012 Wiley Periodicals, Inc.

  2. Sr, Nd and Pb Isotope Systematics of the Cenozoic Volcanism in the Algerian Tell Belt: a Key Constraint on the Geodynamic Evolution of the Westernmost Mediterranean

    Science.gov (United States)

    Meddi, Yassamina; Garrido, Carlos J.; Marchesi, Claudio; Louni-Hacini, Amina; Azzouni-Sekkal, Abla; Varas Reus, María Isabel; Harvey, Jason; Hidas, Károly

    2017-04-01

    The geodynamic evolution of the Western Mediterranean is closely linked to the spatio-temporal evolution of the Cenozoic magmatism in this region. Here, we present a detailed Sr-Nd-Pb study of Cenozoic volcanism from the external and the internal zones of the Algerian Tell belt, a segment of paramount importance to unravel the Alpine geodynamic evolution of the westernmost Mediterranean. The age of the studied volcanics rocks ranges from 17 to 3 Ma, and covers the temporal and spatial evolution of magmatism from calc-alkaline rocks with a clear signature of subduction (commonly referred as to orogenic magmatism), followed by progressively younger sub-alkaline and alkaline volcanism. On the basis of their major and trace element composition, the Tell Cenozoic volcanic rocks can be classified into three main groups: (1) a Si-poor group that is composed of basalt, trachybasalt and basaltic trachyandesite; (2) a Si-intermediate group —raging in silica from 56 to 66 wt. %— that is composed of andesite, dacite, trachyandesite et trachydacite; and a (3) Si-rich group —with silica contents generally greater than 66 wt.%— that is constituted by trachydacite, dacite and rhyolite. The Si-poor group occurs only in the External zone and it is characterized by non-radiogenic 87Sr/86Sr ratios, high initial 144Nd/143Nd ratios, significant variation of 206Pb/204Pb and 207Pb/204Pb ratios, and relatively constant 208Pb/204Pb ratios. The Si-intermediate and Si-rich groups from the Internal and External zones show substantial differences. The 206Pb/204Pb ratios of External zone volcanism are relatively constants [18.68-18.86], while they vary significantly in the Internal zone volcanism [18.55-18.92]. On the other hand, the initial 207Pb/204Pb and 208Pb/204Pb ratios in Internal zone volcanism [38.81-38.95] are significantly higher than those of the External zone [38.68-38.84]. These differing isotopic signatures reflect variable source contamination by subducted sediments

  3. Application of heavy stable isotopes in forensic isotope geochemistry: A review

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Jugdeep [W.M. Keck Isotope Laboratory, Department of Earth Sciences, University of California, Santa Cruz, CA 95064 (United States)], E-mail: jaggarwal@pmc.ucsc.edu; Habicht-Mauche, Judith; Juarez, Chelsey [Department of Anthropology, University of California, Santa Cruz, CA 95064 (United States)

    2008-09-15

    Light stable isotopes have been used for many years to characterize the source and transport of materials. More recently heavy isotope systems such as Sr, Nd and Pb have been added to this list in order to aid source identification. With the advent of multiple collector ICP-MS, the range of isotopic tools now available has increased considerably, however, until the isotope systematics of these new non-traditional isotope systems have become better understood, they will not be as useful in characterizing material source and transportation. Applications using heavy metal stable isotopes (mostly traditional heavy isotopes) have reached most avenues in science, including earth sciences, archaeology, anthropology, animal physiology, ecology and toxicology. This field will continue to grow as new applications are developed and techniques become simpler and quicker. This paper provides a review of how this field has grown and presents two new applications using Pb and Sr isotopes in glazes to determine the source of ore used in glazes, and using Sr isotopes to determine the origin of undocumented deceased Mexican border crossers.

  4. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  5. Neutron Capture Cross Sections of Tellurium Isotopes

    Science.gov (United States)

    Eastman, Micah; Krane, Kenneth

    2006-05-01

    Neutron capture by the stable even-mass Te isotopes (A = 120 to 130) produces in the neighboring odd-neutron isotopes a low-spin ground state (1/2 or 3/2) and a high-spin (11/2) isomeric state. By irradiating samples of natural isotopic Te in our reactor, we have measured the neutron capture cross sections for all of the odd-mass radioactive ground states and isomers produced in the capture process. By using Cd-shielded and unshielded irradiations, we have been able to obtain both the effective thermal cross sections and the resonance integrals. Comparison with similar neutron capture processes in Sn isotopes leads to interesting systematic effects, especially among the thermal cross sections of the low-spin and high-spin states.

  6. Organic carbon isotope systematics of coastal marshes

    NARCIS (Netherlands)

    Middelburg, J.J.; Nieuwenhuize, J.; Lubberts, R.K.; Van de Plassche, O.

    1997-01-01

    Measurements of nitrogen, organic carbon and delta(13)C are presented for Spartina-dominated marsh sediments from a mineral marsh in SW Netherlands and from a peaty marsh in Massachusetts, U.S.A. delta(13)C Of organic carbon in the peaty marsh sediments is similar to that of Spartina material,

  7. METHOD OF ISOTOPE CONCENTRATION

    Science.gov (United States)

    Spevack, J.S.

    1957-04-01

    An isotope concentration process is described which consists of exchanging, at two or more different temperature stages, two isotopes of an element between substances that are physically separate from each other and each of which is capable of containing either of the isotopes, and withdrawing from a point between at least two of the temperatare stages one of the substances containing an increased concentration of the desired isotope.

  8. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.; Popa, M.E.; Krol, M.C.; Hofmann, M.E.G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of

  9. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.|info:eu-repo/dai/nl/304838233; Popa, M. E.|info:eu-repo/dai/nl/375806407; Krol, M. C.|info:eu-repo/dai/nl/078760410; Hofmann, M. E. G.|info:eu-repo/dai/nl/374642907

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a

  10. Statistical clumped isotope signatures

    Science.gov (United States)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  11. Silicon isotope and trace element constraints on the origin of similar to 3.5 Ga cherts: Implications for Early Archaean marine environments

    NARCIS (Netherlands)

    van den Boorn, S.; van Bergen, M.J.; Vroon, P.Z.; de Vries, S.T.; Nijman, W.

    2010-01-01

    Silicon (Si) isotope variability in Precambrian chert deposits is significant, but proposed explanations for the observed heterogeneity are incomplete in terms of silica provenance and fractionation mechanisms involved. To address these issues we investigated Si isotope systematics, in conjunction

  12. Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles

    Science.gov (United States)

    Münch, Thomas; Kipfstuhl, Sepp; Freitag, Johannes; Meyer, Hanno; Laepple, Thomas

    2017-09-01

    The isotopic composition of water in ice sheets is extensively used to infer past climate changes. In low-accumulation regions their interpretation is, however, challenged by poorly constrained effects that may influence the initial isotope signal during and after deposition of the snow. This is reflected in snow-pit isotope data from Kohnen Station, Antarctica, which exhibit a seasonal cycle but also strong interannual variations that contradict local temperature observations. These inconsistencies persist even after averaging many profiles and are thus not explained by local stratigraphic noise. Previous studies have suggested that post-depositional processes may significantly influence the isotopic composition of East Antarctic firn. Here, we investigate the importance of post-depositional processes within the open-porous firn (≳ 10 cm depth) at Kohnen Station by separating spatial from temporal variability. To this end, we analyse 22 isotope profiles obtained from two snow trenches and examine the temporal isotope modifications by comparing the new data with published trench data extracted 2 years earlier. The initial isotope profiles undergo changes over time due to downward advection, firn diffusion and densification in magnitudes consistent with independent estimates. Beyond that, we find further modifications of the original isotope record to be unlikely or small in magnitude (≪ 1 ‰ RMSD). These results show that the discrepancy between local temperatures and isotopes most likely originates from spatially coherent processes prior to or during deposition, such as precipitation intermittency or systematic isotope modifications acting on drifting or loose surface snow.

  13. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  14. Stable C, O and clumped isotope systematics and 14C geochronology of carbonates from the Quaternary Chewaucan closed-basin lake system, Great Basin, USA: Implications for paleoenvironmental reconstructions using carbonates

    Science.gov (United States)

    Hudson, Adam M.; Quade, Jay; Ali, Guleed; Boyle, Douglas; Bassett, Scott; Huntington, Katharine W.; De los Santos, Marie G.; Cohen, Andrew S.; Lin, Ke; Wang, Xiangfeng

    2017-09-01

    Isotopic compositions of lacustrine carbonates are commonly used for dating and paleoenvironmental reconstructions. Here we use carbonate δ13C and δ18O, clumped (Δ47), and 14C compositions to better understand the carbonate isotope system in closed-basin lakes and trace the paleohydrologic and temperature evolution in the Chewaucan closed-basin lake system, northern Great Basin, USA, over the Last Glacial/Holocene transition. We focus on shorezone tufas to establish that they form in isotopic equilibrium with lake water and DIC, they can be dated reliably using 14C, and their clumped isotope composition can be used to reconstruct past lake temperature. Calculations of the DIC budget and reservoir age for the lake indicate residence time is short, and dominated by exchange with atmospheric CO2 at all past lake levels. Modern lake DIC and shorezone tufas yield δ13C and 14C values consistent with isotopic equilibrium with recent fossil fuel and bomb-influenced atmospheric CO2, supporting these calculations. δ13C values of fossil tufas are also consistent with isotopic equilibrium with pre-industrial atmospheric CO2 at all shoreline elevations. This indicates that the 14C reservoir effect for this material is negligible. Clumped isotope (Δ47) results indicate shorezone tufas record mean annual lake temperature. Modern (average 13 ± 2 °C) and 18 ka BP-age tufas (average 6 ± 2 °C) have significantly different temperatures consistent with mean annual temperature lowering of 7 ± 3 °C (1 SE) under full glacial conditions. For shorezone tufas and other lake carbonates, including spring mounds, mollusk shells, and ostracod tests, overall δ13C and δ18O values co-vary according to the relative contribution of spring and lacustrine end member DIC and water compositions in the drainage system, but specific isotope values depend strongly upon sample context and are not well correlated with past lake depth. This contrasts with the interpretation that carbonate

  15. Stable C, O and clumped isotope systematics and 14C geochronology of carbonates from the Quaternary Chewaucan closed-basin lake system, Great Basin, USA: Implications for paleoenvironmental reconstructions using carbonates

    Science.gov (United States)

    Hudson, Adam; Quade, Jay; Ali, Guleed; Boyle, Douglas P.; Bassett, Scott; Huntington, Katharine W.; De los Santos, Marie G.; Cohen, Andrew S.; Lin, Ke; Wang, Xiangfeng

    2017-01-01

    Isotopic compositions of lacustrine carbonates are commonly used for dating and paleoenvironmental reconstructions. Here we use carbonate δ13C and δ18O, clumped (Δ47), and 14C compositions to better understand the carbonate isotope system in closed-basin lakes and trace the paleohydrologic and temperature evolution in the Chewaucan closed-basin lake system, northern Great Basin, USA, over the Last Glacial/Holocene transition. We focus on shorezone tufas to establish that they form in isotopic equilibrium with lake water and DIC, they can be dated reliably using 14C, and their clumped isotope composition can be used to reconstruct past lake temperature. Calculations of the DIC budget and reservoir age for the lake indicate residence time is short, and dominated by exchange with atmospheric CO2 at all past lake levels. Modern lake DIC and shorezone tufas yield δ13C and 14C values consistent with isotopic equilibrium with recent fossil fuel and bomb-influenced atmospheric CO2, supporting these calculations. δ13C values of fossil tufas are also consistent with isotopic equilibrium with pre-industrial atmospheric CO2 at all shoreline elevations. This indicates that the 14C reservoir effect for this material is negligible. Clumped isotope (Δ47) results indicate shorezone tufas record mean annual lake temperature. Modern (average 13 ± 2 °C) and 18 ka BP-age tufas (average 6 ± 2 °C) have significantly different temperatures consistent with mean annual temperature lowering of 7 ± 3 °C (1 SE) under full glacial conditions. For shorezone tufas and other lake carbonates, including spring mounds, mollusk shells, and ostracod tests, overall δ13C and δ18O values co-vary according to the relative contribution of spring and lacustrine end member DIC and water compositions in the drainage system, but specific isotope values depend strongly upon sample context and are not well correlated with past lake depth. This contrasts with the interpretation that carbonate

  16. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. For this reason the Cr isotope system is being developed as a potential tool for paleo-redox reconstruction. Dissolved Cr in seawater...... is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river water and to quantify...

  17. Multiconfiguration calculations of electronic isotope-shift factors in Zn i

    Science.gov (United States)

    Filippin, Livio; Bieroń, Jacek; Gaigalas, Gediminas; Godefroid, Michel; Jönsson, Per

    2017-10-01

    The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of electronic isotope-shift factors for a set of transitions between low-lying states in neutral zinc. These electronic quantities, together with observed isotope shifts between different pairs of isotopes, provide the changes in mean-square charge radii of the atomic nuclei. Within this computational approach, different models for electron correlation are explored in a systematic way to determine a reliable computational strategy and to estimate theoretical error bars of the isotope-shift factors.

  18. Sourcing explosives: a multi-isotope approach.

    Science.gov (United States)

    Widory, David; Minet, Jean-Jacques; Barbe-Leborgne, Martine

    2009-06-01

    Although explosives are easily identified with current instrumental techniques, it is generally impossible to distinguish between sources of the same substance. To alleviate this difficulty, we present a multi-stable isotope (delta13C, delta15N, delta18O, deltaD) approach for appraising the possibility of discriminating explosives. The results from 30 distinct PETN, TNT and ANFO samples show that the different families of explosives are clearly differentiated by both their specific isotope signatures and their combination with corresponding element concentrations. Coupling two or more of the studied isotope systematics yields an even more precise differentiation on the basis of their raw-material origin and/or manufacturing process.

  19. Stable water isotope patterns in a climate change hotspot: the isotope hydrology framework of Corsica (western Mediterranean).

    Science.gov (United States)

    van Geldern, Robert; Kuhlemann, Joachim; Schiebel, Ralf; Taubald, Heinrich; Barth, Johannes A C

    2014-06-01

    The Mediterranean is regarded as a region of intense climate change. To better understand future climate change, this area has been the target of several palaeoclimate studies which also studied stable isotope proxies that are directly linked to the stable isotope composition of water, such as tree rings, tooth enamel or speleothems. For such work, it is also essential to establish an isotope hydrology framework of the region of interest. Surface waters from streams and lakes as well as groundwater from springs on the island of Corsica were sampled between 2003 and 2009 for their oxygen and hydrogen isotope compositions. Isotope values from lake waters were enriched in heavier isotopes and define a local evaporation line (LEL). On the other hand, stream and spring waters reflect the isotope composition of local precipitation in the catchment. The intersection of the LEL and the linear fit of the spring and stream waters reflect the mean isotope composition of the annual precipitation (δP) with values of-8.6(± 0.2) ‰ for δ(18)O and-58(± 2) ‰ for δ(2)H. This value is also a good indicator of the average isotope composition of the local groundwater in the island. Surface water samples reflect the altitude isotope effect with a value of-0.17(± 0.02) ‰ per 100 m elevation for oxygen isotopes. At Vizzavona Pass in central Corsica, water samples from two catchments within a lateral distance of only a few hundred metres showed unexpected but systematic differences in their stable isotope composition. At this specific location, the direction of exposure seems to be an important factor. The differences were likely caused by isotopic enrichment during recharge in warm weather conditions in south-exposed valley flanks compared to the opposite, north-exposed valley flanks.

  20. Diffusive Fractionation of Lithium Isotopes in Olivine

    Science.gov (United States)

    Homolova, V.; Richter, F. M.; Watson, E. B.; Chaussidon, M.

    2014-12-01

    Systematic lithium isotope variations along concentration gradients found in olivine and pyroxene grains from terrestrial, lunar and martian rocks have been attributed to diffusive isotopic fractionation [Beck et al., 2006; Tang et al., 2007]. In some cases, these isotopic excursions are so large that a single grain may display isotopic variability that spans almost the entire range of documented terrestrial values [Jeffcoate et al., 2007]. In this study, we present the results of experiments to examine diffusive isotopic fractionation of lithium in olivine. The experiments comprised crystallographically oriented slabs of San Carlos olivine juxtaposed with either spodumene powder or a lithium rich pyroxene crystal. Experiments were conducted at 1 GPa and 0.1MPa over a temperature range of 1000 to 1125⁰C. Oxygen fugacity in the 0.1MPa experiments was controlled using the wustite-magnetite and nickel-nickel oxide solid buffer assemblages. Lithium concentrations generally decrease smoothly away from the edges of the grains; however, experiments involving diffusion parallel to the a-axis consistently show peculiar wavy or segmented concentration profiles. Lithium diffusivity parallel to the c-axis is on the order of 1E-14m2/s at 1100⁰C. The diffusivity parallel to the c-axis is more than an order of magnitude faster than diffusion parallel to the b-axis and correlates positively with oxygen fugacity. The lithium isotopic composition, δ7Li = 1000‰ * ((δ7Lisample- δ7Ligrain center)/ δ7Ligrain center), shows a decrease away from the edge of the grain to a minimum value (up to 70‰ lighter) and then an abrupt increase back to the initial isotopic composition of the olivine grain. This isotopic profile is similar to those found in natural grains and an experimental study on diffusive fractionation of lithium isotopes in pyroxene [Richter et al., 2014]. Results from the present study are modeled using the approach of Dohmen et al. [2010], which assumes lithium

  1. What can Fe stable isotopes tell us about magmas?

    DEFF Research Database (Denmark)

    Stausberg, Niklas

    in magmas, Fe. Fe isotope compositions of magmatic rocks exhibit systematic differences, where the heaviest compositions are found in rhyolites and granites. Understanding of these systematics is complicated by a lack of constraints on Fe isotope fractionation among minerals and liquids under magmatic...... the differentiation of magmas from the perspective of Fe stable isotopes, integrated with petrology, by studying igneous rocks and their constituent phases (minerals and glasses) from the Bushveld Complex, South Africa, Thingmuli, Iceland, Pantelleria, Italy, and the Bishop Tuff, USA. The findings are interpreted...... in terms of available theory, experiments and forward modeling incorporating petrologic constraints. Mafic cumulate rocks from the Bushveld Complex exhibit resolvable whole rock Fe isotopic variation with modal mineralogy and mineral composition, to a 1st order reflecting partitioning of Fe3+ and Fe2...

  2. Palaeoproterozoic continental arc magmatism, and Neoproterozoic metamorphism in the Aravalli-Delhi orogenic belt, NW India: New constraints from in situ zircon U-Pb-Hf isotope systematics, monazite dating and whole-rock geochemistry

    Science.gov (United States)

    Kaur, Parampreet; Zeh, Armin; Chaudhri, Naveen

    2017-04-01

    Presently, the extent, origin and petrogenesis of late Palaeoproterozoic (ca. 1.85 Ga) magmatism in the north-central Aravalli-Delhi orogenic belt, NW India and subsequent metamorphic overprints are poorly constrained. Results of new in situ zircon U-Pb-Hf isotope analyses in combination with whole-rock elemental and isotopic data provide the first hard evidence that granitoid magmatism occurred in a continental magmatic arc setting between 1.86 and 1.81 Ga. The Hf-Nd model ages of 3.0-2.6 Ga and inherited zircon grains of 3.3-2.5 Ga indicate abundant reworking of Archaean crust. Flat HREE patterns with negative Eu anomalies furthermore reveal that the granitoids were generated from garnet-free and plagioclase-rich sources at shallow depths. Significant isotope variation among granitoid samples (εHft = -3.7 to -9.0; εNdt = -4.8 to -7.9) indicate that the reworked Archaean crust was not completely homogenised during the Palaeoproterozoic. This is best reflected by zircon Hf-isotope variation of ca. 9.5 epsilon units within the oldest granitoid sample. Zircon grains from this sample define three discrete Hf-isotope groups at εHf1.86Ga = -8.9, -4.8 and -1.6. These are interpreted to result from mixing of zircon-saturated magmas derived from three distinct sources within the crust prior to solidification. A monazite U-Pb isochron age of 868 ± 4 Ma from one of the granitoid samples furthermore indicates that the Aravalli fold belt was affected by an important post-magmatic overprint, perhaps related to the widespread metasomatic, granulite metamorphic and/or magmatic events during the same time span.

  3. Oxygen isotope fractionation in double carbonates.

    Science.gov (United States)

    Zheng, Yong-Fei; Böttcher, Michael E

    2016-01-01

    Oxygen isotope fractionations in double carbonates of different crystal structures were calculated by the increment method. Synthesis experiments were performed at 60 °C and 100 °C to determine oxygen and carbon isotope fractionations involving PbMg[CO3]2. The calculations suggest that the double carbonates of calcite structure are systematically enriched in (18)O relative to those of aragonite and mixture structures. Internally consistent oxygen isotope fractionation factors are obtained for these minerals with respect to quartz, calcite and water at a temperature range of 0-1200 °C. The calculated fractionation factors for double carbonate-water systems are generally consistent with the data available from laboratory experiments. The experimentally determined fractionation factors for PbMg[CO3]2, BaMg[CO3]2 and CaMg[CO3]2 against H2O not only fall between fractionation factors involving pure carbonate end-members but are also close to the calculated fractionation factors. In contrast, experimentally determined carbon isotope fractionation factors between PbMg[CO3]2 and CO2 are much closer to theoretical predictions for the cerussite-CO2 system than for the magnesite-CO2 system, similar to the fractionation behavior for BaMg[CO3]2. Therefore, the combined theoretical and experimental results provide insights into the effects of crystal structure and exchange kinetics on oxygen isotope partitioning in double carbonates.

  4. Zn Isotope Fractionation during Sorption onto Kaolinite.

    Science.gov (United States)

    Guinoiseau, Damien; Gélabert, Alexandre; Moureau, Julien; Louvat, Pascale; Benedetti, Marc F

    2016-02-16

    In this study, we quantify zinc isotope fractionation during its sorption onto kaolinite, by performing experiments under various pH, ionic strength, and total Zn concentrations. A systematic enrichment in heavy Zn isotopes on the surface of kaolinite was measured, with Δ(66)Znadsorbed-solution ranging from 0.11‰ at low pH and low ionic strength to 0.49‰ at high pH and high ionic strength. Both the measured Zn concentration and its isotopic ratio are correctly described using a thermodynamic sorption model that considers two binding sites: external basal surfaces and edge sites. Based on this modeling approach, two distinct Zn isotopic fractionation factors were calculated: Δ(66)Znadsorbed-solution = 0.18 ± 0.06‰ for ion exchange onto basal sites, and Δ(66)Znadsorbed-solution = 0.49 ± 0.06‰ for specific complexation onto edge sites. These two distinct factors indicate that Zn isotope fractionation is dominantly controlled by the chemical composition of the solution (pH, ionic strength).

  5. Tracing source pollution in soils using cadmium and lead isotopes.

    Science.gov (United States)

    Cloquet, C; Carignan, J; Libourel, G; Sterckeman, T; Perdrix, E

    2006-04-15

    Tracing the source of heavy metals in the environment is of key importance for our understanding of their pollution and natural cycles in the surface Earth reservoirs. Up to now, most exclusively Pb isotopes were used to effectively trace metal pollution sources in the environment. Here we report systematic variations of Cd isotope ratios measured in polluted topsoils surrounding a Pb-Zn refinery plant in northern France. Fractionated Cd was measured in soil samples surrounding the refinery, and this fractionation can be attributed to the refining processes. Despite the Cd isotopic ratios being precisely measured, the obtained uncertainties are still large compared to the total isotopic variation. Nevertheless, for the first time, Cd isotopically fractionated by industrial processes may be traced in the environment. On the same samples, Pb isotope systematics suggested that materials actually used by the refinery were not the major source of Pb in soils, probably because refined ore origins changed over the 100 years of operation. On the other hand, Cd isotopes and concentrations measured in topsoils allowed identification of three main origins (industrial dust and slag and agriculture), assuming that all Cd ores are not fractionated, as suggested by terrestrial rocks so far analyzed, and calculation of their relative contributions for each sampling point. Understanding that this refinery context was an ideal situation for such a study, our results lead to the possibility of tracing sources of anthropogenic Cd and better constrain mixing processes, fluxes, transport, and phasing out of industrial input in nature.

  6. Discovery of the Indium Isotopes

    CERN Document Server

    Amos, S

    2010-01-01

    Thirty-eight indium isotopes (A = 98-135) have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  7. Paired Sr isotope (87Sr/86Sr, δ88/86Sr) systematic of pore water profiles: A new perspective in marine weathering and seepage studies

    OpenAIRE

    Liebetrau, Volker; Haeckel, Matthias; Eisenhauer, Anton; Scholz, Florian; Hensen, Christian; Reitz, Anja

    2011-01-01

    The simultaneous and independent determination of the radiogenic (87Sr/86Sr) and the fractionation reflecting stable (!88/86Sr) Sr isotope ratio on pore waters, sediments and precipitates (e.g. carbonates and sulfates) opens a new perspective in the field of submarine weathering and Sr contribution to the ocean chemistry. Four initial case studies covering (1.) CO2 seeps of the Okinawa Trough (OT), (2.) mud volcanoes (MV) and mounds in the Gulf of Cadiz (GoC) and the (...

  8. Systematic of dipole excitations in the stable sup 1 sup 3 sup 4 sup , sup 1 sup 3 sup 5 sup , sup 1 sup 3 sup 6 sup , sup 1 sup 3 sup 7 sup , sup 1 sup 3 sup 8 Ba isotopes

    CERN Document Server

    Scheck, M; Brentano, P V

    2002-01-01

    In this contribution the focus is on the systematic study of [2 sup + x3 sup -] sub 1 -two-phonon excitations around the Z = 50 and N = 82 shell closures. The results for the Sn and Ba isotope chains will be shown in a general framework of all available data obtained by nuclear resonance fluorescence experiments. The photon scattering experiments referred to in this work were performed at the Bremsstrahlung facility of the 4.3 MV Stuttgart Dynamitron accelerator. NRF experiments are suitable for the determination of excitation energies, spins, lifetimes and transition strengths of low-spin states. The even-even isotopes show strong 1 sup - excitations close to the sum energy of the 2 sup + and 3 sup - phonons, interpreted as [2 sup + x3 sup -] sub 1 -two phonon excitations. The behaviour of these [2 sup + x 3 sup -] sub 1 -states in even-even nuclei can be explained by the so-called DCP effect. Furthermore, the coupling of a single nucleon to this collective excitation in the neighbouring odd-mass nuclei is i...

  9. SHELL ISOTOPE GEOCHEMISTRY

    African Journals Online (AJOL)

    Valley. Although fossil specimens of this subspecies have been used in palaeoclimatic reconstruction, there have been no previous reports of living examples. Here We describe the local habitat, climate and some aspects of ecology and isotopic variation within the snail shell. If isotope data can be obtained for fossil shells, ...

  10. ICT: isotope correction toolbox.

    Science.gov (United States)

    Jungreuthmayer, Christian; Neubauer, Stefan; Mairinger, Teresa; Zanghellini, Jürgen; Hann, Stephan

    2016-01-01

    Isotope tracer experiments are an invaluable technique to analyze and study the metabolism of biological systems. However, isotope labeling experiments are often affected by naturally abundant isotopes especially in cases where mass spectrometric methods make use of derivatization. The correction of these additive interferences--in particular for complex isotopic systems--is numerically challenging and still an emerging field of research. When positional information is generated via collision-induced dissociation, even more complex calculations for isotopic interference correction are necessary. So far, no freely available tools can handle tandem mass spectrometry data. We present isotope correction toolbox, a program that corrects tandem mass isotopomer data from tandem mass spectrometry experiments. Isotope correction toolbox is written in the multi-platform programming language Perl and, therefore, can be used on all commonly available computer platforms. Source code and documentation can be freely obtained under the Artistic License or the GNU General Public License from: https://github.com/jungreuc/isotope_correction_toolbox/ {christian.jungreuthmayer@boku.ac.at,juergen.zanghellini@boku.ac.at} Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  11. Methodology for the Validation of Isotopic Analyses by Mass Spectrometry in Stable-Isotope Labeling Experiments.

    Science.gov (United States)

    Heuillet, Maud; Bellvert, Floriant; Cahoreau, Edern; Letisse, Fabien; Millard, Pierre; Portais, Jean-Charles

    2018-02-06

    Stable-isotope labeling experiments (ILEs) are widely used to investigate the topology and operation of metabolic networks. The quality of isotopic data collected in ILEs is of utmost importance to ensure reliable biological interpretations, but current evaluation approaches are limited due to a lack of suitable reference material and relevant evaluation criteria. In this work, we present a complete methodology to evaluate mass spectrometry (MS) methods used for quantitative isotopic studies of metabolic systems. This methodology, based on a biological sample containing metabolites with controlled labeling patterns, exploits different quality metrics specific to isotopic analyses (accuracy and precision of isotopologue masses, abundances, and mass shifts and isotopic working range). We applied this methodology to evaluate a novel LC-MS method for the analysis of amino acids, which was tested on high resolution (Orbitrap operating in full scan mode) and low resolution (triple quadrupole operating in multiple reaction monitoring mode) mass spectrometers. Results show excellent accuracy and precision over a large working range and revealed matrix-specific as well as mode-specific characteristics. The proposed methodology can identify reliable (and unreliable) isotopic data in an easy and straightforward way and efficiently supports the identification of sources of systematic biases as well as of the main factors that influence the overall accuracy and precision of measurements. This approach is generic and can be used to validate isotopic analyses on different matrices, analytical platforms, labeled elements, or classes of metabolites. It is expected to strengthen the reliability of isotopic measurements and thereby the biological value of ILEs.

  12. Chlorine and Bromine Isotope Fractionation of Halogenated Organic Pollutants on Gas Chromatography Columns

    OpenAIRE

    Tang, Caiming; Tan, Jianhua; Xiong, Songsong; Liu, Jun; Fan, Yujuan; Peng, Xianzhi

    2017-01-01

    Compound-specific chlorine/bromine isotope analysis (CSIA-Cl/Br) has become a useful approach for degradation pathway investigation and source appointment of halogenated organic pollutants (HOPs). CSIA-Cl/Br is usually conducted by gas chromatography-mass spectrometry (GC-MS), which could be negatively impacted by chlorine and bromine isotope fractionation of HOPs on GC columns. In this study, 31 organochlorines and 4 organobromines were systematically investigated in terms of Cl/Br isotope f...

  13. Isotope Fractionation Associated with the Photochemical Dechlorination of Chloroanilines.

    Science.gov (United States)

    Ratti, Marco; Canonica, Silvio; McNeill, Kristopher; Bolotin, Jakov; Hofstetter, Thomas B

    2015-08-18

    Isotope fractionation associated with the photochemical transformation of organic contaminants is not well understood and can arise not only from bond cleavage reactions but also from photophysical processes. In this work, we investigated the photolytic dechlorination of 2-Cl- and 3-Cl-aniline to aminophenols to obtain insights into the impact of the substituent position on the apparent (13)C and (15)N kinetic isotope effects (AKIEs). Laboratory experiments were performed in aerated aqueous solutions at an irradiation wavelength of 254 nm over the pH range 2.0 to 7.0 in the absence and presence of Cs(+) used as an excited singlet state quencher. Photolysis of 2-Cl-anilinium cations exhibits normal C and inverse N isotope fractionation, while neutral 2-Cl-aniline species shows inverse C and normal N isotope fractionation. In contrast, the photolysis of 3-Cl-aniline was almost insensitive to C isotope composition and the moderate N isotope fractionation points to rate-limiting photophysical processes. (13)C- and (15)N-AKIE-values of 2-Cl-aniline decreased in the presence of Cs(+), whereas those for 3-Cl-aniline were not systematically affected by Cs(+). Our current and previous work illustrates that photolytic dechlorinations of 2-Cl-, 3-Cl-, and 4-Cl-aniline isomers are each accompanied by distinctly different and highly variable C and N isotope fractionation due to spin selective isotope effects.

  14. Resetting of Mg isotopes between calcite and dolomite during burial metamorphism: Outlook of Mg isotopes as geothermometer and seawater proxy

    Science.gov (United States)

    Hu, Zhongya; Hu, Wenxuan; Wang, Xiaomin; Lu, Yizhou; Wang, Lichao; Liao, Zhiwei; Li, Weiqiang

    2017-07-01

    Magnesium isotopes are an emerging tool to study the geological processes recorded in carbonates. Calcite, due to its ubiquitous occurrence and the large Mg isotope fractionation associated with the mineral, has attracted great interests in applications of Mg isotope geochemistry. However, the fidelity of Mg isotopes in geological records of carbonate minerals (e.g., calcite and dolomite) against burial metamorphism remains poorly constrained. Here we report our investigation on the Mg isotope systematics of a dolomitized Middle Triassic Geshan carbonate section in eastern China. Magnesium isotope analysis was complemented by analyses of Sr-C-O isotopic compositions, major and trace element concentrations, and petrographic and mineralogical features. Multiple lines of evidence consistently indicated that post-depositional diagenesis of carbonate minerals occurred to the carbonate rocks. Magnesium isotope compositions of the carbonate rocks closely follow a mixing trend between a high δ26Mg dolomite end member and a low δ26Mg calcite end member, irrespective of sample positions in the section and calcite/dolomite ratio in the samples. By fitting the measured Mg isotope data using a two-end member mixing model, an inter-mineral Δ26Mgdolomite-calcite fractionation of 0.72‰ was obtained. Based on the experimentally derived Mg isotope fractionation factors for dolomite and calcite, a temperature of 150-190 °C was calculated to correspond to the 0.72‰ Δ26Mgdolomite-calcite fractionation. Such temperature range matches with the burial-thermal history of the local strata, making a successful case of Mg isotope geothermometry. Our results indicate that both calcite and dolomite had been re-equilibrated during burial metamorphism, and based on isotope mass balance of Mg, the system was buffered by dolomite in the section. Therefore, burial metamorphism may reset Mg isotope signature of calcite, and Mg isotope compositions in calcite should be dealt with caution in

  15. U-Pb isochron age and Pb isotope systematics of the Golden Fleece vein - implications for the relationship of mineralization to the Lake City caldera, western San Juan Mountains, Colorado.

    Science.gov (United States)

    Hon, K.; Ludwig, K. R.; Simmons, K.R.; Slack, J.F.; Grauch, R.I.

    1985-01-01

    A U/Pb isochron age of 27.5 + or - 0.5 m.y. is determined for the Golden Fleece vein, an age which is identical with the age of the quartz latite lavas that the vein cuts. Within the Lake City area, only the Golden Fleece vein contains pitchblende and Au-Ag tellurides and has Pb isotope ratios that together define it as unique within the area. The 27.5 m.y. age relates this vein to the waning stages of the Uncompahgre caldera (27-29) rather than to the Lake City caldera (23.1 m.y.). -G.J.N.

  16. Iron Isotope Fractionation in Artic Weathering Environments

    Science.gov (United States)

    Rouxel, O. J.; Escoube, R.; Pokrovsky, O. S.; Wisch, M.; Miller, C.

    2008-12-01

    While our current knowledge of Fe isotope systematics in rivers is still limited, Fe isotopes provide a new approach to important questions concerning Fe sources, Fe speciation and its bioavailability in the hydrological cycles. Here, we investigated several Arctic rivers for elemental and Fe-isotopic composition with specific emphasis on silicate weathering and organic C content in order to provide new insights into the delivery of trace nutrients, such as Fe, that are important for the biological productivity of the Arctic Ocean. Without such characterization of the present state of the system, future changes in the response of these river systems to global change cannot be properly evaluated. Our Fe isotope systematics results in Siberian rivers, include (1) a time-series of water samples from large rivers (Ob and Lena) focusing on the peak flow that has not yet been investigated despite its critical importance for annual budgets; (2) the colloidal fractions (1 kDa to 0.45 μm) of rivers and their estuaries in the White Sea, including the Severnaya Dvina River to assess the influence of Fe-rich colloids flocculation on the Fe isotopic composition of the estuarine waters. Dissolved iron fractions (ice break-up on the rivers. In contrast, dissolved iron fractions in the Severnaya Dvina River and its tributaries yield more positive δ56Fe values, with values ranging from -0.09 to up to 0.64‰, averaging 0.2‰ (n=19). Small swamp rivers from the South White Sea coast reveal an even higher spread of dissolved δ56Fe values, from -1.1 to +0.8‰ with some clear variations among the various colloidal fractions (1 kDa-10 kDa - 100 kDa). These results, together with the high Fe and DOC concentrations in the water samples, suggest that Fe-redox cycling in soil aquifer, as well as the formation of organic-rich colloids, may impart specific Fe-isotope signatures in dissolved Fe reaching the Artic Ocean. Recent studies (e.g. Fantle and De Paolo, 2004 and Bergquist and

  17. Geochemistry of the stable isotopes of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Douthitt, C.B. (California Inst. of Tech., Pasadena (USA). Div. of Geological and Planetary Sciences)

    1982-08-01

    One hundred thirty two new measurements of the relative abundances of the stable isotopes of silicon in terrestrial materials are presented. The total variation of delta/sup 30/Si found is 6.2 parts per thousand, centered on the mean of terrestrial mafic and ultramafic igneous rocks, delta/sup 30/Si = -0.4 parts per thousand. Igneous rocks show limited variation; coexisting minerals exhibit small, systematic silicon isotopic fractionations that are roughly 1/3 the magnitude of concomitant oxygen isotopic fractionations at 1150/sup 0/C. In both igneous minerals and rocks, delta/sup 30/Si shows a positive correlation with silicon content, as does delta/sup 18/O. Opal from both sponge spicules and sinters is light, with delta/sup 30/Si = -2.3 and -1.4 parts per thousand respectively. Large delta/sup 30/Si values of both positive and negative sign are reported for the first time from clay minerals, opaline phytoliths, and authigenic quartz. All highly fractionated samples were precipitated from solution at low temperatures; however, aqueous silicon is not measurably fractionated relative to quartz at equilibrium. A kinetic isotope fractionation of approximately 3.5 parts per thousand is postulated to occur during the low temperature precipitation of opal and, possibly, poorly ordered phyllosilicates, with the silicate phase being enriched in /sup 28/Si. This fractionation, coupled with a Rayleigh precipitation model, is capable of explaining most non-magmatic delta/sup 30/Si variations.

  18. Measurement system analysis (MSA) of the isotopic ratio for uranium isotope enrichment process control

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, Josue C. de; Barbosa, Rodrigo A.; Carnaval, Joao Paulo R., E-mail: josue@inb.gov.br, E-mail: rodrigobarbosa@inb.gov.br, E-mail: joaocarnaval@inb.gov.br [Industrias Nucleares do Brasil (INB), Rezende, RJ (Brazil)

    2013-07-01

    Currently, one of the stages in nuclear fuel cycle development is the process of uranium isotope enrichment, which will provide the amount of low enriched uranium for the nuclear fuel production to supply 100% Angra 1 and 20% Angra 2 demands. Determination of isotopic ration n({sup 235}U)/n({sup 238}U) in uranium hexafluoride (UF{sub 6} - used as process gas) is essential in order to control of enrichment process of isotopic separation by gaseous centrifugation cascades. The uranium hexafluoride process is performed by gas continuous feeding in separation unit which uses the centrifuge force principle, establishing a density gradient in a gas containing components of different molecular weights. The elemental separation effect occurs in a single ultracentrifuge that results in a partial separation of the feed in two fractions: an enriched on (product) and another depleted (waste) in the desired isotope ({sup 235}UF{sub 6}). Industrias Nucleares do Brasil (INB) has used quadrupole mass spectrometry (QMS) by electron impact (EI) to perform isotopic ratio n({sup 235}U)/n({sup 238}U) analysis in the process. The decision of adjustments and change te input variables are based on the results presented in these analysis. A study of stability, bias and linearity determination has been performed in order to evaluate the applied method, variations and systematic errors in the measurement system. The software used to analyze the techniques above was the Minitab 15. (author)

  19. Isotopes through the looking glass

    Science.gov (United States)

    Mårtensson Pendrill, Ann Marie

    2000-08-01

    Nuclear distributions affect many aspects of atomic spectra. As an example, recent experimental results for the hyperfine anomaly in Fr isotopes are considered. These depend on nuclear charge and magnetization distributions. The variations in charge radii for these isotopes were studied earlier by measuring optical isotope shifts. The hyperfine anomalies for the odd-odd isotopes involve the neutron distributions, of interest for studies of parity nonconserving effects along a chain of isotopes.

  20. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  1. Isotope Production Facility (IPF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Los Alamos National Laboratory has produced radioactive isotopes for medicine and research since the mid 1970s, when targets were first irradiated using the 800...

  2. Isotopes in Greenland Precipitation

    DEFF Research Database (Denmark)

    Faber, Anne-Katrine

    ) Constructing a new Greenland database of observations and present-day ice core measurements, and (3) Performance test of isotope-enabled CAM5 for Greenland. The recent decades of rapid Arctic sea ice decline are used as a basis for an observational-based model experiment using the isotope-enabled CAM model 3....... The simulation of Greenland isotopes is tested for the isotope-enabled model CAM5. Here the importance of model resolution is investigated. A positive bias of 6-10 ‰ is found for the annual mean δ18O on the central part of the Greenland Ice Sheet. The amplitude of the seasonal cycle of Greenland δ18O is highly...

  3. Isotope toolbox turns 10

    DEFF Research Database (Denmark)

    Wenander, Fredrik; Riisager, Karsten

    2012-01-01

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

  4. Isotope research materials

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, M. K.; Young, Jr, F. W.

    1977-10-01

    Preparation of research isotope materials is described. Topics covered include: separation of tritium from aqueous effluents by bipolar electrolysis; stable isotope targets and research materials; radioisotope targets and research materials; preparation of an 241Am metallurgical specimen; reactor dosimeters; ceramic and cermet development; fission-fragment-generating targets of 235UO2; and wire dosimeters for Westinghouse--Bettis. (GHT)

  5. Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles

    Directory of Open Access Journals (Sweden)

    T. Münch

    2017-09-01

    Full Text Available The isotopic composition of water in ice sheets is extensively used to infer past climate changes. In low-accumulation regions their interpretation is, however, challenged by poorly constrained effects that may influence the initial isotope signal during and after deposition of the snow. This is reflected in snow-pit isotope data from Kohnen Station, Antarctica, which exhibit a seasonal cycle but also strong interannual variations that contradict local temperature observations. These inconsistencies persist even after averaging many profiles and are thus not explained by local stratigraphic noise. Previous studies have suggested that post-depositional processes may significantly influence the isotopic composition of East Antarctic firn. Here, we investigate the importance of post-depositional processes within the open-porous firn (≳ 10 cm depth at Kohnen Station by separating spatial from temporal variability. To this end, we analyse 22 isotope profiles obtained from two snow trenches and examine the temporal isotope modifications by comparing the new data with published trench data extracted 2 years earlier. The initial isotope profiles undergo changes over time due to downward advection, firn diffusion and densification in magnitudes consistent with independent estimates. Beyond that, we find further modifications of the original isotope record to be unlikely or small in magnitude (≪ 1 ‰ RMSD. These results show that the discrepancy between local temperatures and isotopes most likely originates from spatially coherent processes prior to or during deposition, such as precipitation intermittency or systematic isotope modifications acting on drifting or loose surface snow.

  6. Age and isotopic systematics of Cretaceous borehole and surface samples from the greater Los Angeles Basin region: Implications for the types of crust that might underlie Los Angeles and their distribution along late Cenozoic fault systems

    Science.gov (United States)

    Premo, Wayne R.; Morton, Douglas M.; Kistler, Ronald W.

    2014-01-01

    Nine U-Pb zircon ages were determined on plutonic rocks sampled from surface outcrops and rock chips of drill core from boreholes within the greater Los Angeles Basin region. In addition, lead-strontium-neodymium (Pb-Sr-Nd) whole-rock isotopic data were obtained for eight of these samples. These results help to characterize the crystalline basement rocks hidden in the subsurface and provide information that bears on the tectonic history of the myriad of fault systems that have dissected the Los Angeles region over the past 15 m.y. Seven of the nine samples have U-Pb ages ranging from 115 to 103 Ma and whole-rock Pb-Sr-Nd isotopic characteristics that indicate the crystalline basement underneath the greater Los Angeles Basin region is mostly part of the Peninsular Ranges batholith. Furthermore, these data are interpreted as evidence for (1) the juxtaposition of mid-Cretaceous, northern Peninsular Ranges batholith plutonic rocks against Late Cretaceous plutonic rocks of the Transverse Ranges in the San Fernando Valley, probably along the Verdugo fault; (2) the juxtaposition of older northwestern Peninsular Ranges batholith rocks against younger northeastern Peninsular Ranges batholith rocks in the northern Puente Hills, implying transposition of northeastern Peninsular Ranges batholith rocks to the west along unrecognized faults beneath the Chino Basin; and (3) juxtaposition of northern Peninsular Ranges batholith plutonic rocks against Late Cretaceous plutonic rocks of the Transverse Ranges along the San Jose fault in the northern San Jose Hills at Ganesha Park. These mainly left-lateral strike-slip faults of the eastern part of the greater Los Angeles Basin region could be the result of block rotation within the adjacent orthogonal, right-lateral, Elsinore-Whittier fault zone to the west and the subparallel San Jacinto fault zone to the east. The San Andreas fault system is the larger, subparallel, driving force further to the east.

  7. Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation.

    Science.gov (United States)

    Carlson, Richard W; Borg, Lars E; Gaffney, Amy M; Boyet, Maud

    2014-09-13

    New Rb-Sr, (146,147)Sm-(142,143)Nd and Lu-Hf isotopic analyses of Mg-suite lunar crustal rocks 67667, 76335, 77215 and 78238, including an internal isochron for norite 77215, were undertaken to better define the time and duration of lunar crust formation and the history of the source materials of the Mg-suite. Isochron ages determined in this study for 77215 are: Rb-Sr=4450±270 Ma, (147)Sm-(143)Nd=4283±23 Ma and Lu-Hf=4421±68 Ma. The data define an initial (146)Sm/(144)Sm ratio of 0.00193±0.00092 corresponding to ages between 4348 and 4413 Ma depending on the half-life and initial abundance used for (146)Sm. The initial Nd and Hf isotopic compositions of all samples indicate a source region with slight enrichment in the incompatible elements in accord with previous suggestions that the Mg-suite crustal rocks contain a component of KREEP. The Sm/Nd-(142)Nd/(144)Nd correlation shown by both ferroan anorthosite and Mg-suite rocks is coincident with the trend defined by mare and KREEP basalts, the slope of which corresponds to ages between 4.35 and 4.45 Ga. These data, along with similar ages for various early Earth differentiation events, are in accord with the model of lunar formation via giant impact into Earth at ca 4.4 Ga. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  8. Optimizing isotope substitution in graphene for thermal conductivity minimization by genetic algorithm driven molecular simulations

    Science.gov (United States)

    Davies, Michael; Ganapathysubramanian, Baskar; Balasubramanian, Ganesh

    2017-03-01

    We present results from a computational framework integrating genetic algorithm and molecular dynamics simulations to systematically design isotope engineered graphene structures for reduced thermal conductivity. In addition to the effect of mass disorder, our results reveal the importance of atomic distribution on thermal conductivity for the same isotopic concentration. Distinct groups of isotope-substituted graphene sheets are identified based on the atomic composition and distribution. Our results show that in structures with equiatomic compositions, the enhanced scattering by lattice vibrations results in lower thermal conductivities due to the absence of isotopic clusters.

  9. Zircon Lu-Hf isotope systematics and U-Pb geochronology, whole-rock Sr-Nd isotopes and geochemistry of the early Jurassic Gokcedere pluton, Sakarya Zone-NE Turkey: a magmatic response to roll-back of the Paleo-Tethyan oceanic lithosphere

    Science.gov (United States)

    Karsli, Orhan; Dokuz, Abdurrahman; Kandemir, Raif

    2017-05-01

    The early Mesozoic was a critical era for the geodynamic evolution of the Sakarya Zone as transition from accretion to collision events in the region. However, its complex evolutionary history is still debated. To address this issue, we present new in situ zircon U-Pb ages and Lu-Hf isotope data, whole-rock Sr-Nd isotopes, and mineral chemistry and geochemistry data of plutonic rocks to better understand the magmatic processes. The Gokcedere pluton is mainly composed of gabbro and gabbroic diorite. LA-ICP-MS zircon U-Pb dating reveals that the pluton was emplaced in the early Jurassic (177 Ma). These gabbros and gabbroic diorites are characterized by relatively low SiO2 content of 47.09 to 57.15 wt% and high Mg# values varying from 46 to 75. The samples belong to the calc-alkaline series and exhibit a metaluminous I-type character. Moreover, they are slightly enriched in large ion lithophile elements (Rb, Ba, Th and K) and light rare earth elements and depleted in high field strength elements (Nb and Ti). Gabbroic rocks of the pluton have a depleted Sr-Nd isotopic composition, including low initial 87Sr/86Sr ranging from 0.705124 to 0.705599, relatively high ɛ Nd ( t) values varying from 0.1 to 3.5 and single-stage Nd model ages ( T DM1 = 0.65-0.95 Ga). In situ zircon analyses show that the rocks have variable and positive ɛ Hf ( t) values (4.6 to 13.5) and single-stage Hf model ages ( T DM1 = 0.30 to 0.65 Ga). Both the geochemical signature and Sr-Nd-Hf isotopic composition of the gabbroic rocks reveal that the magma of the studied rocks was formed by the partial melting of a depleted mantle wedge metasomatized by slab-derived fluids. The influence of slab fluids is mirrored by their trace-element characteristics. Trace-element modeling suggests that the primary magma was generated by a low and variable degree of partial melting ( 5-15%) of a depleted and young lithospheric mantle wedge consisting of phlogopite- and spinel-bearing lherzolite. Heat to melt the

  10. Transportation of medical isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, D.L.

    1997-11-19

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

  11. Isotope geochemistry. Biological signatures in clumped isotopes of O₂.

    Science.gov (United States)

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

    2015-04-24

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of "clumped" isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in (18)O(18)O and (17)O(18)O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling. Copyright © 2015, American Association for the Advancement of Science.

  12. Petrology, 40Ar/39Ar age, Sr-Nd isotope systematics, and geodynamic significance of an ultrapotassic (lamproitic) dyke with affinities to kamafugite from the easternmost margin of the Bastar Craton, India

    Science.gov (United States)

    Rao, N. V. Chalapathi; Atiullah; Burgess, R.; Nanda, Purnendu; Choudhary, A. K.; Sahoo, Samarendra; Lehmann, B.; Chahong, Ngazipmi

    2016-04-01

    We report the mineralogy, bulk-rock geochemistry, 40Ar/39Ar (whole-rock) age and radiogenic (Sr and Nd) isotope composition of an ultrapotassic dyke from Sakri (Nuapada lamproite field) located at the tectonic contact between the easternmost margin of the Bastar craton and Eastern Ghats Mobile Belt, India. The Sakri dyke has a mineralogy which strongly resembles a lamproite sensu stricto (viz.,Ti-rich phlogopite, Na-poor diopside, Fe-rich sanidine, ulvospinel trend and Sr-rich apatite). However, its bulk-rock major element geochemical characteristics (viz., extreme silica-undersaturated nature) resemble sensu lato kamafugite from Toro Ankole, Uganda, East African Rift, and Alto Paranaiba Province, Brazil. The Sakri dyke also displays certain compositional peculiarities (viz., high degree of evolution of mica composition from phlogopite to biotite, elevated titanium and aluminum in clinopyroxene and significantly lower bulk Mg#) when compared to the ultrapotassic rocks from various Indian cratons. 40Ar/39Ar dating gave a plateau age of 1045 ± 9 Ma which is broadly similar to that of other Mesoproterozoic (i) lamproites from the Bastar and Bundelkhand cratons, and (ii) kimberlites from the Eastern Dharwar craton. Initial bulk-rock Sr (0.705865-0.709024) and Nd (0.511063-0.511154) isotopic ratios reveal involvement of an `enriched' source region with long-term incompatible element enrichment and a depleted mantle (TDM) Nd model age of 2.56 Ga straddling the Archaean-Proterozoic chronostratigraphic boundary. The bulk-rock incompatible trace element ratios (Ta/Yb, Th/Yb, Rb/Ba and Ce/Y) of the Sakri ultrapotassic dyke negate any significant influence of crustal contamination. Small-degree melting (1 to 1.5 %) of a mixed garnet-facies and spinel-facies phlogopite lherzolite can account for its observed REE concentrations. Whereas the emplacement of the Sakri ultrapotassic dyke is related to the amalgamation of the supercontinent of Rodinia, its overlapping geochemical

  13. Cadmium Isotope Fractionation in Soil-Wheat Systems.

    Science.gov (United States)

    Wiggenhauser, Matthias; Bigalke, Moritz; Imseng, Martin; Müller, Michael; Keller, Armin; Murphy, Katy; Kreissig, Katharina; Rehkämper, Mark; Wilcke, Wolfgang; Frossard, Emmanuel

    2016-09-06

    Analyses of stable metal isotope ratios constitute a novel tool in order to improve our understanding of biogeochemical processes in soil-plant systems. In this study, we used such measurements to assess Cd uptake and transport in wheat grown on three agricultural soils under controlled conditions. Isotope ratios of Cd were determined in the bulk C and A horizons, in the Ca(NO3)2-extractable Cd soil pool, and in roots, straw, and grains. The Ca(NO3)2-extractable Cd was isotopically heavier than the Cd in the bulk A horizon (Δ(114/110)Cdextract-Ahorizon = 0.16 to 0.45‰). The wheat plants were slightly enriched in light isotopes relative to the Ca(NO3)2-extractable Cd or showed no significant difference (Δ(114/110)Cdwheat-extract = -0.21 to 0.03‰). Among the plant parts, Cd isotopes were markedly fractionated: straw was isotopically heavier than roots (Δ(114/110)Cdstraw-root = 0.21 to 0.41‰), and grains were heavier than straw (Δ(114/110)Cdgrain-straw = 0.10 to 0.51‰). We suggest that the enrichment of heavy isotopes in the wheat grains was caused by mechanisms avoiding the accumulation of Cd in grains, such as the chelation of light Cd isotopes by thiol-containing peptides in roots and straw. These results demonstrate that Cd isotopes are significantly and systematically fractionated in soil-wheat systems, and the fractionation patterns provide information on the biogeochemical processes in these systems.

  14. Stable isotope analysis of Dacryoconarid carbonate microfossils: a new tool for Devonian oxygen and carbon isotope stratigraphy.

    Science.gov (United States)

    Frappier, Amy Benoit; Lindemann, Richard H; Frappier, Brian R

    2015-04-30

    Dacryoconarids are extinct marine zooplankton known from abundant, globally distributed calcite microfossils in the Devonian, but their shell stable isotope composition has not been previously explored. Devonian stable isotope stratigraphy is currently limited to less common invertebrates or bulk rock analyses of uncertain provenance. As with Cenozoic planktonic foraminifera, isotopic analysis of dacryoconarid shells could facilitate higher-resolution, geographically widespread stable isotope records of paleoenvironmental change, including marine hypoxia events, climate changes, and biocrises. We explored the use of Dacryoconarid isotope stratigraphy as a viable method in interpreting paleoenvironments. We applied an established method for determining stable isotope ratios (δ(13) C, δ(18) O values) of small carbonate microfossils to very well-preserved dacryoconarid shells. We analyzed individual calcite shells representing five common genera using a Kiel carbonate device coupled to a MAT 253 isotope ratio mass spectrometer. Calcite shell δ(13) C and δ(18) O values were compared by taxonomic group, rock unit, and locality. Single dacryoconarid calcite shells are suitable for stable isotope analysis using a Kiel-IRMS setup. The dacryoconarid shell δ(13) C values (-4.7 to 2.3‰) and δ(18) O values (-10.3 to -4.8‰) were consistent across taxa, independent of shell size or part, but varied systematically through time. Lower fossil δ(18) O values were associated with warmer water temperature and more variable δ(13) C values were associated with major bioevents. Dacryoconarid δ(13) C and δ(18) O values differed from bulk rock carbonate values. Dacryoconarid individual microfossil δ(13) C and δ(18) O values are highly sensitive to paleoenvironmental changes, thus providing a promising avenue for stable isotope chemostratigraphy to better resolve regional to global paleoceanographic changes throughout the upper Silurian to the upper Devonian. Our results

  15. Isotopes in Condensed Matter

    CERN Document Server

    G Plekhanov, Vladimir

    2013-01-01

    This book provides a concise introduction to the newly created sub-discipline of solid state physics isotopetronics. The role of isotopes in materials and their properties are describe  in this book. The problem of the enigma of the atomic mass in microphysics is briefly discussed.  The range of the applications of isotopes is wide: from biochemical process in living organisms to modern technical applications in quantum information. Isotopetronics promises to improve nanoelectronic and optoelectronic devices. With numerous illustrations this book is useful to researchers, engineers and graduate students.

  16. Discoveries of isotopes by fission

    Indian Academy of Sciences (India)

    About 3000 different isotopes have been discovered until now. A recent compilation sum- marized details of the discovery of all isotopes [1–4] including the year, laboratory and country of discovery as well as the production mechanism used to produce the isotopes. Fission, one of the largest contributing production ...

  17. Hydrogen isotope systematics in C3 and C4 saltmarsh plants: the importance of biochemical processes in controlling interspecies variation in n-alkane 2H/1H composition

    Science.gov (United States)

    Eley, Y.; Pedentchouk, N.

    2013-12-01

    Palaeohydrological studies have increasingly utilised the 2H/1H composition of leaf wax n-alkyl lipids to extract information from the geological record. Interpretation of the sedimentary biomarker δ2H signal, however, requires detailed understanding of the mechanisms controlling hydrogen isotope fractionation between source water and n-alkyl lipids (ɛl/w). The existence of large ranges in published n-alkyl δ2H and ɛl/w among modern plant species growing at a single location suggests that the lipid signal incorporated into the sedimentary record could be sensitive to relatively small-scale changes in vegetation assemblages. The mechanisms responsible for these interspecies differences are currently poorly constrained. Previous research has had limited success explaining n-alkyl δ2H by reference to physical processes controlling the movement of water inside/outside and within the leaf, while the relative importance of biochemical processes remains largely unexplored. This project aims to identify the mechanisms controlling interspecies variation in n-alkane 2H/1H among a range of C3 and C4 plants from a Norfolk saltmarsh in the UK. To distinguish between environmental, physical and biochemical controls, we conducted 2H/1H analysis of soil, xylem, and leaf waters and n-alkanes (i) across multiple sampling sites within the marsh, (ii) throughout the 2012 growth season, and (iii) at different times of the day. We also measured the 2H/1H of chloroplast phytol in 7 samples collected at the end of 2012. Leaf wax n-alkane δ2H varied among the sampled species by over 100‰ throughout the 2012 growth season. Environmental processes that could influence control source water 2H/1H did not fully account for this interspecies variation - soil water 2H/1H varied by only 35‰ with marsh sub-environment and exhibited site-specific seasonal shifts by no more than 31‰. Maximum interspecies variation in xylem water was 38‰, while leaf waters differed by only 29‰. We

  18. An extremely low U Pb source in the Moon: UThPb, SmNd, RbSr, and 40Ar 39Ar isotopic systematics and age of lunar meteorite Asuka 881757

    Science.gov (United States)

    Misawa, K.; Tatsumoto, M.; Dalrymple, G.B.; Yanai, K.

    1993-01-01

    We have undertaken UThPb, SmNd, RbSr, and 40Ar 39Ar isotopic studies on Asuka 881757, a coarse-grained basaltic lunar meteorite whose chemical composition is close to low-Ti and very low-Ti (VLT) mare basalts. The PbPb internal isochron obtained for acid leached residues of separated mineral fractions yields an age of 3940 ?? 28 Ma, which is similar to the U-Pb (3850 ?? 150 Ma) and Th-Pb (3820 ?? 290 Ma) internal isochron ages. The Sm-Nd data for the mineral separates yield an internal isochron age of 3871 ?? 57 Ma and an initial 143Nd 144Nd value of 0.50797 ?? 10. The Rb-Sr data yield an internal isochron age of 3840 ?? 32 Ma (??(87Rb) = 1.42 ?? 10-11 yr-1) and a low initial 87Sr 86Sr ratio of 0.69910 ?? 2. The 40Ar 39Ar age spectra for a glass fragment and a maskelynitized plagioclase are relatively flat and give a weighted mean plateau age of 3798 ?? 12 Ma. We interpret these ages to indicate that the basalt crystallized from a melt 3.87 Ga ago (the Sm-Nd age) and an impact event disturbed the Rb-Sr system and completely reset the K-Ar system at 3.80 Ga. The slightly higher Pb-Pb age compared to the Sm-Nd age could be due to the secondary Pb (from terrestrial and/or lunar surface Pb contamination) that remained in the residues after acid leaching. Alternatively, the following interpretation is also possible; the meteorite crystallized at 3.94 Ga (the Pb-Pb age) and the Sm-Nd, Rb-Sr, and K-Ar systems were disturbed by an impact event at 3.80 Ga. The crystallization age obtained here is older than those reported for low-Ti basalts (3.2-3.5 Ga) and for VLT basalts (3.4 Ga), but similar to ages of some mare basalts, indicating that the basalt may have formed from a magma related to a basin-forming event (Imbrium?). The age span for VLT basalts from different sampling sites suggest that they were erupted over a wide area during an interval of at least ~500 million years. The impact event that thermally reset the K-Ar system of Asuka 881757 must have been post

  19. Hydrothermal alteration, fluid inclusions and stable isotope systematics of the Alvo 118 iron oxide-copper-gold deposit, Carajás Mineral Province (Brazil): Implications for ore genesis

    Science.gov (United States)

    Torresi, Ignacio; Xavier, Roberto Perez; Bortholoto, Diego F. A.; Monteiro, Lena V. S.

    2012-03-01

    ), together with available boron isotope and Cl/Br-Na/Cl data provide evidence for a significant component of residual evaporative fluids (e.g., bittern fluids generated by seawater evaporation) in this scenario that, together with magma-derived brines, would be the main sources of the highly saline fluids involved in the formation Alvo 118 IOCG deposit. The restricted high temperature sodic alteration, the pervasive overprinting of the potassic alteration minerals by chlorite proximal to the ore zones, ore breccias with open-space filling textures in brittle structures, microthermometric and stable isotope data indicate, collectively, that the Alvo 118 IOCG system developed at structurally high levels and may be considered the shallower representative of the IOCG systems of the CMP.

  20. Re-partitioning of Cu and Zn isotopes by modified protein expression

    Directory of Open Access Journals (Sweden)

    Ragnarsdottir K Vala

    2008-10-01

    Full Text Available Abstract Cu and Zn have naturally occurring non radioactive isotopes, and their isotopic systematics in a biological context are poorly understood. In this study we used double focussing mass spectroscopy to determine the ratios for these isotopes for the first time in mouse brain. The Cu and Zn isotope ratios for four strains of wild-type mice showed no significant difference (δ65Cu -0.12 to -0.78 permil; δ66Zn -0.23 to -0.48 permil. We also looked at how altering the expression of a single copper binding protein, the prion protein (PrP, alters the isotope ratios. Both knockout and overexpression of PrP had no significant effect on the ratio of Cu isotopes. Mice brains expressing mutant PrP lacking the known metal binding domain have δ65Cu isotope values of on average 0.57 permil higher than wild-type mouse brains. This implies that loss of the copper binding domain of PrP increases the level of 65Cu in the brain. δ66Zn isotope values of the transgenic mouse brains are enriched for 66Zn to the wild-type mouse brains. Here we show for the first time that the expression of a single protein can alter the partitioning of metal isotopes in mouse brains. The results imply that the expression of the prion protein can alter cellular Cu isotope content.

  1. PGE abundance and Re-Os isotope Systematics of Native-Fe-Bearing Basaltic Rocks and Their Carbonaceous Crustal Contaminants: Insights into magma plumbing-system dynamics in LIPs

    Science.gov (United States)

    Howarth, G. H.; Day, J. M.; Goodrich, C. A.; Pernet-Fisher, J.; Pearson, D. G.; Taylor, L. A.

    2014-12-01

    Native-Fe grains form in basaltic melts at highly reducing conditions (Igneous Province (LIP). The reducing conditions recorded are the direct result of assimilation of carbonaceous crustal material during emplacement of the basaltic magmas at or near the surface. Native Fe-bearing basalts are useful natural analogues for studying PGE pre-concentration mechanisms, and the potential for PGE additions to magmas from crustal sources. Here, we present PGE LA-ICP-MS data for Fe-alloy, cohenite, and sulfide for a suite of Siberian and Disko Island native-Fe basalts, in combination with whole-rock PGE data for all known occurrences. The Siberian native-Fe alloys are characterized by highly variable PGE concentrations (1-30 ppm total PGEs), distinct low Os abundances, and PGE profiles similar to those of the nearby Noril'sk sulfide ores. In contrast, the Disko Island alloys are characterized by total PGE concentrations of 1-10 ppm and distinct positive Os and Re anomalies in extended PGE profiles. The Bühl basalts contain low PGE concentrations (~20 ppb). In order to understand contamination contributions, Os-isotopes analyses have been performed. Preliminary whole-rock 187Os/188Os data for high metal content samples from Siberia (0.33606 ± 37) and Disko (0.15402 ± 15) indicate high-time integrated Re/Os. The Re anomalies observed in extended PGE profiles of the Disko Island samples may reflect a potential crustal contribution to the overall PGE budget, through the addition of carbonaceous material. Whereas the Siberian samples contain abundant carbonaceous xenoliths, there is no apparent PGE contribution from crustal materials. Therefore, the role of crustal contamination is important in forming the native-Fe alloys, but the interaction of concomitant contamination, fractional crystallization, and native-Fe segregation varies according to location and style of crust-melt interactions within a LIP; e.g., lavas (Disko) versus intrusions (Siberia).

  2. Isotopic composition of Pb and Th in interplinian volcanics from Somma-Vesuvius volcano, Italy

    Science.gov (United States)

    Cortini, M.; Ayuso, R.A.; de Vivo, B.; Holden, P.; Somma, R.

    2004-01-01

    We present a detailed isotopic study of volcanic rocks emitted from Somma-Vesuvius volcano during three periods of interplinian activity: "Protohistoric" (3550 y B.P. to 79 A.D.), "Ancient Historic" (79 to 472 A.D.) and "Medieval" (472 to 1631 A.D.). Pb isotopic compositions of two acid leached fractions and whole rock residues of 37 whole rock samples (determined by Somma et al., 2001) show that each of the three interplinian periods is distinguished by small, systematic, and unique uranogenic and thorogenic Pb isotopic trends. This key and novel feature is compatible with the notion that the Pb isotopic data reflect small-scale source heterogeneity operating over relatively short periods of time. From this representative group of samples, a selected set of nine whole rocks were analysed for Th isotopes. 232Th/238U ratios in the source can be obtained independently from Pb and from Th isotopes. Those obtained from Pb isotopes represent source ratios, time-integrated over the whole age of the Earth; they range from 3.9 to 4.1. 232Th/238U obtained from Th isotopes are those of the present source. They are lower, and cluster around 3.5; this difference probably indicates recent U enrichment of the present source. The behaviour of Pb, as inferred by its isotopic ratios, is quite distinct from that of Sr and Nd isotopes: Pb isotope variations are not correlated to Sr or Nd isotope variations. The isotopic contrast is compatible with the idea that the isotopes were decoupled during magmatic production, evolution, and ascent through the crust. Thus, the Pb isotopes do not reflect the effects of the same processes as in the case of the Sr and Nd isotopes, or, as we also favor, they do not necessarily reflect the same source contributions into the magmas. Moreover, the Pb isotopic evolution of the interplinian rocks chiefly reflects mixing, driven by processes that are superimposed on, and independent of, other source contributions that determine the isotopic compositions

  3. Expanding the isotopic toolbox: Applications of hydrogen and oxygen stable isotope ratios to food web studies

    Directory of Open Access Journals (Sweden)

    Hannah B Vander Zanden

    2016-03-01

    Full Text Available The measurement of stable carbon (δ13C and nitrogen (δ15N isotopes in tissues of organisms has formed the foundation of isotopic food web reconstructions, as these values directly reflect assimilated diet. In contrast, stable hydrogen (δ2H and oxygen (δ18O isotope measurements have typically been reserved for studies of migratory origin and paleoclimate reconstruction based on systematic relationships between organismal tissue and local environmental water. Recently, innovative applications using δ2H and, to a lesser extent, δ18O values have demonstrated potential for these elements to provide novel insights in modern food web studies. We explore the advantages and challenges associated with three applications of δ2H and δ18O values in food web studies. First, large δ2H differences between aquatic and terrestrial ecosystem end members can permit the quantification of energy inputs and nutrient fluxes between these two sources, with potential applications for determining allochthonous vs. autochthonous nutrient sources in freshwater systems and relative aquatic habitat utilization by terrestrial organisms. Next, some studies have identified a relationship between δ2H values and trophic position, which suggests that this marker may serve as a trophic indicator, in addition to the more commonly used δ15N values. Finally, coupled measurements of δ2H and δ18O values are increasing as a result of reduced analytical challenges to measure both simultaneously and may provide additional ecological information over single element measurements. In some organisms, the isotopic ratios of these two elements are tightly coupled, whereas the isotopic disequilibrium in other organisms may offer insight into the diet and physiology of individuals. Although a coherent framework for interpreting δ2H and δ18O data in the context of food web studies is emerging, many fundamental uncertainties remain. We highlight directions for targeted research that

  4. Diversity of sulfur isotope fractionations by sulfate-reducing prokaryotes

    DEFF Research Database (Denmark)

    Detmers, Jan; Brüchert, Volker; Habicht, K S

    2001-01-01

    Batch culture experiments were performed with 32 different sulfate-reducing prokaryotes to explore the diversity in sulfur isotope fractionation during dissimilatory sulfate reduction by pure cultures. The selected strains reflect the phylogenetic and physiologic diversity of presently known...... sulfate reducers and cover a broad range of natural marine and freshwater habitats. Experimental conditions were designed to achieve optimum growth conditions with respect to electron donors, salinity, temperature, and pH. Under these optimized conditions, experimental fractionation factors ranged from 2.......0 to 42.0 per thousand. Salinity, incubation temperature, pH, and phylogeny had no systematic effect on the sulfur isotope fractionation. There was no correlation between isotope fractionation and sulfate reduction rate. The type of dissimilatory bisulfite reductase also had no effect on fractionation...

  5. Zircon ages, geochemistry and Nd isotopic systematics for the Palaeoproterozoic 2.3-1.8 Ga Kuilyu Complex, East Kyrgyzstan - The oldest continental basement fragment in the Tianshan orogenic belt

    Science.gov (United States)

    Kröner, A.; Alexeiev, D. V.; Kovach, V. P.; Rojas-Agramonte, Y.; Tretyakov, A. A.; Mikolaichuk, A. V.; Xie, H.; Sobel, E. R.

    2017-03-01

    Precambrian microcontinents represent key tectonic units in the accretionary collages of the western Central Asian Orogenic Belt (CAOB), and their geological history is reasonably well established since the Mesoproterozoic but remains weakly constrained for older epochs due to a scarcity of exposed Palaeoproterozoic and Archaean rocks. Early Precambrian rocks were previously reported from several metamorphic complexes in the Kyrgyz Tianshan orogenic belt, mainly based on multigrain conventional zircon dating, but the present study only confirmed such rocks at one site, namely in the Kuilyu Complex of eastern Kyrgyzstan. New single grain SHRIMP II zircon ages, geochemical data, and whole-rock Nd isotopic compositions for granitoid gneisses of the Kuilyu Complex elucidate the age, origin and tectonic settings of this oldest continental fragment in the Tianshan. The Kuilyu Complex is part of the basement in the Ishim - Middle Tianshan microcontinent. It consist of a strongly deformed and metamorphosed supracrustal assemblage of paragneisses and schists which are tectonically interlayered with amphibolites, migmatites and granitoid gneisses. Our zircon dating indicates that the Kuilyu Complex contains two suites of Palaeoproterozoic granitoid gneisses with magmatic protolith ages of ca. 2.32-2.33 Ga and 1.85 Ga. Granitoid magmatism at 1.85 Ga was almost immediately followed by amphibolite-facies metamorphism at ca 1.83 Ga, evidenced by growth of metamorphic zircon rims. The older, ca 2.3 Ga granitoid gneisses chemically correspond to calc-alkaline, metaluminous, I-type magnesian quartz diorite and granodiorite. The protolith of the younger, ca. 1.85 Ga granite-gneiss is an alkalic-calcic, metaluminous to peraluminous, ferroan medium-grained porphyric granite with chemical features resembling A-type granites. The 2.3 Ga and 1.85 Ga granitoid gneisses have slightly to distinctly negative initial εNd values of -1.2 and -6.6, and similar depleted mantle Nd model ages of 2

  6. New Isotope 263Hs

    Energy Technology Data Exchange (ETDEWEB)

    Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Dvorak, J.; Ellison, P.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Nitsche, H.

    2010-03-16

    A new isotope of Hs was produced in the reaction 208Pb(56Fe, n)263Hs at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope 263Hs. The measured cross section was 21+13-8.4 pb at 276.4 MeV lab-frame center-of-target beam energy. 263Hs decays with a half-life of 0.74 ms by alpha-decay and the measured alpha-particle energies are 10.57 +- 0.06, 10.72 +- 0.06, and 10.89 +- 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. Swiatecki et al., Phys. Rev. C 71, 014602 (2005)].

  7. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  8. Laboratory and field methods for stable isotope analysis in human biology.

    Science.gov (United States)

    Reitsema, Laurie J

    2015-01-01

    Stable isotope analysis (SIA; carbon, hydrogen, nitrogen, sulfur, and oxygen) of human tissues offers a means for assessing diet among living humans. Stable isotope ratios of broad categories of food and drink food vary systematically, and stable isotope ratios in consumer tissues represent a composite of the isotopic ratios of food and drink consumed during an individual's life. Isotopic evidence for diet is independent of errors in informant recall, and accrues during time periods when researchers are absent. Beyond diet reconstruction, tissue stable isotope ratios are sensitive to excursions from homeostasis, such as starvation and rapid growth. Because of their relationship to diet, geographic location, hydration, and nutritional status, stable isotope signatures in human tissues offer a window into human biocultural adaptations, past and present. This article describes methods for SIA that may be usefully applied in studies of living humans, with emphasis placed on carbon and nitrogen. Some of the ecological, physiological, and evolutionary applications of stable isotope data among living humans are discussed. By incorporating SIA in research, human biologists facilitate a productive dialog with bioarchaeologists, who routinely use stable isotope evidence, mingling different perspectives on human biology and behavior. © 2015 Wiley Periodicals, Inc.

  9. Rb-Sr and Sm-Nd Ages of Zagami DML and SR Isotopic Heterogeneity in Zagami

    Science.gov (United States)

    Nyquist, L.aurenceE.; Shih, C.-Y.; Reese, Y. D.

    2010-01-01

    Zagami contains lithologic heterogeneity suggesting that it did not form in a homogeneous, thick lava flow [1]. We have previously investigated the Sr and Nd isotopic systematics of Coarse-Grained (CG) and Fine-Grained (FG) lithologies described by [2]. Both appear to belong to Normal Zagami (NZ) [1,3], but their initial Sr-isotopic compositions differ [4,5]. Here we report new analyses of the Dark Mottled Lithology (DML, [3]) that show its age and initial Sr and Nd isotopic compositions to be identical within error limits with those of CG, but Sr initial isotopic compositions differ from those of FG.

  10. Therapeutic use of radioactive isotopes

    CERN Multimedia

    Caroline Duc

    2013-01-01

    In December, researchers from ISOLDE-CERN, the Paul Scherrer Institute (PSI) and the Institut Laue-Langevin (ILL) published the results of an in vivo study which successfully proved the effectiveness of four terbium isotopes for diagnosing and treating cancerous tumours.   Four terbium isotopes suitable for clinical purposes. “ISOLDE is the only installation capable of supplying terbium isotopes of such purity and intensity in the case of three out of the four types used in this study,” explains Karl Johnson, a physicist at ISOLDE.  “Producing over a thousand different isotopes, our equipment offers the widest choice of isotopes in the world!” Initially intended for fundamental physics research, ISOLDE has diversified its activities over time to invest in various projects in the materials science, biochemistry and nuclear medicine fields. The proof-of-concept study has confirmed that the four terbium isotopes 149Tb, 152Tb, 155Tb produ...

  11. Water isotope tracers of tropical hydroclimate in a warming world

    Science.gov (United States)

    Konecky, B. L.; Noone, D.; Nusbaumer, J. M.; Cobb, K. M.; Di Nezio, P. N.; Otto-Bliesner, B. L.

    2016-12-01

    The tropical water cycle is projected to undergo substantial changes under a warming climate, but direct meteorological observations to contextualize these changes are rare prior to the 20th century. Stable oxygen and hydrogen isotope ratios (δ18O, δD) of environmental waters preserved in geologic archives are increasingly being used to reconstruct terrestrial rainfall over many decades to millions of years. However, a rising number of new, modern-day observations and model simulations have challenged previous interpretations of these isotopic signatures. This presentation systematically evaluates the three main influences on the δ18O and δD of modern precipitation - rainfall amount, cloud type, and moisture transport - from terrestrial stations throughout the tropics, and uses this interpretive framework to understand past changes in terrestrial tropical rainfall. Results indicate that cloud type and moisture transport have a larger influence on modern δ18O and δD of tropical precipitation than previously believed, indicating that isotope records track changes in cloud characteristics and circulation that accompany warmer and cooler climate states. We use our framework to investigate isotopic records of the land-based tropical rain belt during the Last Glacial Maximum, the period of warming following the Little Ice Age, and the 21st century. Proxy and observational data are compared with water isotope-enabled simulations with the Community Earth System Model in order to discuss how global warming and cooling may influence tropical terrestrial hydroclimate.

  12. IUPAC Periodic Table of Isotopes for the Educational Community

    Energy Technology Data Exchange (ETDEWEB)

    Holden N. E.; Holden,N.E.; Coplen,T.B.

    2012-07-15

    John Dalton first proposed the concept of atomic weights of the elements in the first decade of the nineteenth century. These atomic weights of the chemical elements were thought of as constants of nature, similar to the speed of light. Dmitri Mendeleev arranged the atomic weights of the elements in ascending order of value and used the systematic variation of their chemical properties to produce his Periodic Table of the Elements in 1869. Measurement of atomic weight values became an important chemical activity for a century and a half. Theodore Richards received a Noble Prize for his work in this area. In 1913, Fredrick Soddy found a species of radium, which had an atomic weight value of 228, compared to the familiar radium gas value of 226. Soddy coined the term 'isotope' (Greek for 'in the same place') to account for this second atomic weight value in the radium position of the Periodic Table. Both of these isotopes of radium are radioactive. Radioactive isotopes are energetically unstable and will decay (disintegrate) over time. The time it takes for one half of a sample of a given radioactive isotope to decay is the half-life of that isotope. In addition to having different atomic weight values, radium-226 and radium-228 also have different half-life values. Around the same time as Soddy's work, J.J. Thomson (discoverer of the electron) identified two stable (non-radioactive) isotopes of the same element, neon. Over the next 40 years, the majority of the known chemical elements were found to have two or more stable (or long-lived radioactive isotopes that contribute significantly to the determination of the atomic weights of the elements).

  13. The Schwartzwalder uranium deposit, II: Age of uranium mineralization and lead isotope constraints on genesis.

    Science.gov (United States)

    Ludwig, K. R.; Wallace, A.R.; Simmons, K.R.

    1985-01-01

    Schwartzwalder ores have high amounts of initial (common) Pb that was both variable and relatively radiogenic in its isotope ratios. Assuming the common Pb in these ores to have sources of similar age and similar Th/U, samples with initial Pb isotope ratios are identified - and others with variable initial ratios are normalized - to obtain U-Pb isochrons yielding an early Laramide age of 69.3 + or - 1.1 m.y. for the ores. The initial Pb-isotope systematics indicate local sources of U, dispersed in concentrations <100 ppm, in rocks of 1730 + or - 130 m.y. age. -G.J.N.

  14. Chlorine and Bromine Isotope Fractionation of Halogenated Organic Compounds in Electron Ionization Mass Spectrometry

    OpenAIRE

    Tang, Caiming; Tan, Jianhua; Shi, Zhiqiang; Tang, Caixing; Xiong, Songsong; Liu, Jun; Fan, Yujuan; Peng, Xianzhi

    2017-01-01

    Revelation of chlorine and bromine isotope fractionation of halogenated organic compounds (HOCs) in electron ionization mass spectrometry (EI-MS) is crucial for compound-specific chlorine/bromine isotope analysis (CSIA-Cl/Br) using gas chromatography EI-MS (GC-EI-MS). This study systematically investigated chlorine/bromine isotope fractionation in EI-MS of HOCs including 12 organochlorines and 5 organobromines using GC-double focus magnetic-sector high resolution MS (GC-DFS-HRMS). Chlorine/br...

  15. In-situ formation, thermal decomposition, and adsorption studies of transition metal carbonyl complexes with short-lived radioisotopes

    Energy Technology Data Exchange (ETDEWEB)

    Even, Julia [Helmholtz-Institut Mainz (Germany); Mainz Univ. (Germany); Duellmann, Emanuel [Mainz Univ. (Germany); Helmholtz-Institut Mainz (Germany); GSI Helmholzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Yakushev, Alexander [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); and others

    2014-07-01

    We report on the in-situ synthesis of metal carbonyl complexes with short-lived isotopes of transition metals. Complexes of molybdenum, technetium, ruthenium and rhodium were synthesized by thermalisation of products of neutron-induced fission of {sup 249}Cf in a carbon monoxide-nitrogen mixture. Complexes of tungsten, rhenium, osmium, and iridium were synthesized by thermalizing short-lived isotopes produced in {sup 24}Mg-induced fusion evaporation reactions in a carbon monoxide containing atmosphere. The chemical reactions took place at ambient temperature and pressure conditions. The complexes were rapidly transported in a gas stream to collection setups or gas phase chromatography devices. The physisorption of the complexes on Au and SiO{sub 2} surfaces was studied. We also studied the stability of some of the complexes, showing that these start to decompose at temperatures above 300 C in contact with a quartz surface. Our studies lay a basis for the investigation of such complexes with transactinides.

  16. Systematic review

    DEFF Research Database (Denmark)

    Enggaard, Helle

    2016-01-01

    I have taken a Comprehensive Systematic Review Training course provide by Center of Clinical Guidelines in Denmark and Jonna Briggs Institute (JBI) and practice in developing a systematic review on how patients with ischemic heart disease experiences peer support. This insight and experience...... with systematic review is used to develop didactic practice end evidence based teaching in different part of the education. Findings: The poster will present how teacher’s training and experiences with systematic review contribute to the nursing education in relation to didactic, research methodology and patient...

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

    Science.gov (United States)

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

    2016-09-01

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

  18. Chromatographic hydrogen isotope separation

    Science.gov (United States)

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  19. Cold regions isotope applications

    Energy Technology Data Exchange (ETDEWEB)

    Perrigo, L.D.; Divine, T.E.

    1976-04-01

    Pacific Northwest Laboratories (PNL) started the Cold Regions Isotope Applications Program in FY-1975 to identify special conditions in the Arctic and similar geographic areas (Cold Regions) where radioisotope power, heater, or sterilization systems would be desirable and economically viable. Significant progress was made in the first year of this program and all objectives for this initial 12-month period were achieved. The major conclusions and recommendations resulting for this effort are described below. The areas of interest covered include: radiosterilization of sewage; heating of septic tanks; and radioisotope thermoelectric generators as power sources for meteorological instruments and navigational aids. (TFD)

  20. ISOTOPE FRACTIONATION PROCESS

    Science.gov (United States)

    Clewett, G.H.; Lee, DeW.A.

    1958-05-20

    A new method is described for isotopic enrichment of uranium. It has been found that when an aqueous acidic solution of ionic tetravalent uraniunn is contacted with chelate complexed tetravalent uranium, the U/sup 238/ preferentially concentrates in the complexed phase while U/sup 235/ concentrates in the ionic phase. The effect is enhanced when the chelate compound is water insoluble and is dissolved in a water-immiscible organic solvent. Cupferron is one of a number of sultable complexing agents, and chloroform is a suitable organic solvent.

  1. Systematic measurements of the Bohr-Weisskopf effect at ISOLDE

    CERN Multimedia

    Nojiri, Y; Matsuki, S; Ragnarsson, I; Neugart, R; Redi, O; Stroke, H H; Duong, H T; Marescaux, D; Pinard, J; Juncar, P; Ekstrom, C; Pellarin, M; Vialle, J-L; Inamura, T

    2002-01-01

    The " Bohr-Weisskopf " effect, or " hyperfine structure (hfs) anomaly ", which results from the effect of the distribution of nuclear magnetization on the electro-nuclear interaction, will be measured systematically at the PS Booster ISOLDE, first for a long chain of radioactive cesium isotopes, analogously to previous isotope shift and hfs studies. In addition to the direct measurement of magnetic moment values, the results are expected to provide independent data for testing nuclear wavefunctions, these will be of importance for interpreting systematic parity non-conservation experiments, complementary to the single isotope study which requires a high precision knowledge of the electron wavefunction. Substantial progress in these calculations has been achieved recently. Precision measurements of the hfs splittings and nuclear magnetic moments are required, with sensitivity adequate for the radioactive isotopes produced. A triple resonance atomic beam magnetic resonance apparatus with optical pumping state s...

  2. Do foraminifera accurately record seawater neodymium isotope composition?

    Science.gov (United States)

    Scrivner, Adam; Skinner, Luke; Vance, Derek

    2010-05-01

    Palaeoclimate studies involving the reconstruction of past Atlantic meridional overturning circulation increasingly employ isotopes of neodymium (Nd), measured on a variety of sample media (Frank, 2002). In the open ocean, Nd isotopes are a conservative tracer of water mass mixing and are unaffected by biological and low-temperature fractionation processes (Piepgras and Wasserburg, 1987; Lacan and Jeandel, 2005). For decades, benthic foraminifera have been widely utilised in stable isotope and geochemical studies, but have only recently begun to be exploited as a widely distributed, high-resolution Nd isotope archive (Klevenz et al., 2008), potentially circumventing the difficulties associated with other methods used to recover past deep-water Nd isotopes (Klevenz et al., 2008; Rutberg et al., 2000; Tachikawa et al., 2004). Thus far, a single pilot study (Klevenz et al., 2008) has indicated that core-top sedimentary benthic foraminifera record a Nd isotope composition in agreement with the nearest available bottom seawater data, and has suggested that this archive is potentially useful on both millennial and million-year timescales. Here we present seawater and proximal core-top foraminifer Nd isotope data for samples recovered during the 2008 "RETRO" cruise of the Marion Dufresne. The foraminifer samples comprise a depth-transect spanning 3000m of the water column in the Angola Basin and permit a direct comparison between high-resolution water column and core-top foraminiferal Nd isotope data. We use these data to assess the reliability of both planktonic and benthic foraminifera as recorders of water column neodymium isotope composition. Frank, M., 2002. Radiogenic isotopes: Tracers of past ocean circulation and erosional input, Rev. Geophys., 40 (1), 1001, doi:10.1029/2000RG000094. Klevenz, V., Vance, D., Schmidt, D.N., and Mezger, K., 2008. Neodymium isotopes in benthic foraminifera: Core-top systematics and a down-core record from the Neogene south Atlantic

  3. Method of separating boron isotopes

    Science.gov (United States)

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

    1984-01-01

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

  4. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    retain an isotopically light Cr signature. Cr(VI) enriched in heavy Cr isotopes is then transported via river waters to the oceans and sequestered into marine sediments. Marine chemical sediments such asbanded iron formations and modern marine carbonates have proven useful in recording the Cr isotope...... with calcium carbonate in order to test the reliability of the Cr carbonate compositions. Several experimental approaches have been employed to elucidate the fractionation behavior of Cr isotopes when Cr(VI) is incorporated into calcium carbonate phases. These results indicate that at lower Cr concentrations......Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past...

  5. Isotopic disproportionation during hydrogen isotopic analysis of nitrogen-bearing organic compounds

    Science.gov (United States)

    Nair, Sreejesh; Geilmann, Heike; Coplen, Tyler B.; Qi, Haiping; Gehre, Matthias; Schimmelmann, Arndt; Brand, Willi A.

    2015-01-01

    Rationale High-precision hydrogen isotope ratio analysis of nitrogen-bearing organic materials using high-temperature conversion (HTC) techniques has proven troublesome in the past. Formation of reaction products other than molecular hydrogen (H2) has been suspected as a possible cause of incomplete H2 yield and hydrogen isotopic fractionation. Methods The classical HTC reactor setup and a modified version including elemental chromium, both operated at temperatures in excess of 1400 °C, have been compared using a selection of nitrogen-bearing organic compounds, including caffeine. A focus of the experiments was to avoid or suppress hydrogen cyanide (HCN) formation and to reach quantitative H2 yields. The technique also was optimized to provide acceptable sample throughput. Results The classical HTC reaction of a number of selected compounds exhibited H2 yields from 60 to 90 %. Yields close to 100 % were measured for the experiments with the chromium-enhanced reactor. The δ2H values also were substantially different between the two types of experiments. For the majority of the compounds studied, a highly significant relationship was observed between the amount of missing H2and the number of nitrogen atoms in the molecules, suggesting the pyrolytic formation of HCN as a byproduct. A similar linear relationship was found between the amount of missing H2 and the observed hydrogen isotopic result, reflecting isotopic fractionation. Conclusions The classical HTC technique to produce H2 from organic materials using high temperatures in the presence of glassy carbon is not suitable for nitrogen-bearing compounds. Adding chromium to the reaction zone improves the yield to 100 % in most cases. The initial formation of HCN is accompanied by a strong hydrogen isotope effect, with the observed hydrogen isotope results on H2 being substantially shifted to more negative δ2H values. The reaction can be understood as an initial disproportionation leading to H2 and HCN

  6. Oxygen Isotope Measurements of a Rare Murchison Type A CAI and Its Rim

    Science.gov (United States)

    Matzel, J. E. P.; Simon, J. I.; Hutcheon, I. D.; Jacobsen, B.; Simon, S. B.; Grossman, L.

    2013-01-01

    Ca-, Al-rich inclusions (CAIs) from CV chondrites commonly show oxygen isotope heterogeneity among different mineral phases within individual inclusions reflecting the complex history of CAIs in both the solar nebula and/or parent bodies. The degree of isotopic exchange is typically mineral-specific, yielding O-16-rich spinel, hibonite and pyroxene and O-16-depleted melilite and anorthite. Recent work demonstrated large and systematic variations in oxygen isotope composition within the margin and Wark-Lovering rim of an Allende Type A CAI. These variations suggest that some CV CAIs formed from several oxygen reservoirs and may reflect transport between distinct regions of the solar nebula or varying gas composition near the proto-Sun. Oxygen isotope compositions of CAIs from other, less-altered chondrites show less intra-CAI variability and 16O-rich compositions. The record of intra-CAI oxygen isotope variability in CM chondrites, which commonly show evidence for low-temperature aqueous alteration, is less clear, in part because the most common CAIs found in CM chondrites are mineralogically simple (hibonite +/- spinel or spinel +/- pyroxene) and are composed of minerals less susceptible to O-isotopic exchange. No measurements of the oxygen isotope compositions of rims on CAIs in CM chondrites have been reported. Here, we present oxygen isotope data from a rare, Type A CAI from the Murchison meteorite, MUM-1. The data were collected from melilite, hibonite, perovskite and spinel in a traverse into the interior of the CAI and from pyroxene, melilite, anorthite, and spinel in the Wark-Lovering rim. Our objectives were to (1) document any evidence for intra-CAI oxygen isotope variability; (2) determine the isotopic composition of the rim minerals and compare their composition(s) to the CAI interior; and (3) compare the MUM-1 data to oxygen isotope zoning profiles measured from CAIs in other chondrites.

  7. Titanium stable isotopic variations in chondrites, achondrites and lunar rocks

    Science.gov (United States)

    Greber, Nicolas D.; Dauphas, Nicolas; Puchtel, Igor S.; Hofmann, Beda A.; Arndt, Nicholas T.

    2017-09-01

    Titanium isotopes are potential tracers of processes of evaporation/condensation in the solar nebula and magmatic differentiation in planetary bodies. To gain new insights into the processes that control Ti isotopic variations in planetary materials, 25 komatiites, 15 chondrites, 11 HED-clan meteorites, 5 angrites, 6 aubrites, a martian shergottite, and a KREEP-rich impact melt breccia have been analyzed for their mass-dependent Ti isotopic compositions, presented using the δ49Ti notation (deviation in permil of the 49Ti/47Ti ratio relative to the OL-Ti standard). No significant variation in δ49Ti is found among ordinary, enstatite, and carbonaceous chondrites, and the average chondritic δ49Ti value of +0.004 ± 0.010‰ is in excellent agreement with the published estimate for the bulk silicate Earth, the Moon, Mars, and the HED and angrite parent-bodies. The average δ49Ti value of komatiites of -0.001 ± 0.019‰ is also identical to that of the bulk silicate Earth and chondrites. OL-Ti has a Ti isotopic composition that is indistinguishable from chondrites and is therefore a suitable material for reporting δ49Ti values. Previously published isotope data on another highly refractory element, Ca, show measurable variations among chondrites. The decoupling between Ca and Ti isotope systematics most likely occurred during condensation in the solar nebula. Aubrites exhibit significant variations in δ49Ti, from -0.07 to +0.24‰. This is likely due to the uniquely reducing conditions under which the aubrite parent-body differentiated, allowing chalcophile Ti3+ and lithophile Ti4+ to co-exist. Consequently, the observed negative correlation between δ49Ti values and MgO concentrations among aubrites is interpreted to be the result of isotope fractionation driven by the different oxidation states of Ti in this environment, such that isotopically heavy Ti4+ was concentrated in the residual liquid during magmatic differentiation. Finally, KREEPy impact melt breccia

  8. Competition from Isotopic Modelling

    Directory of Open Access Journals (Sweden)

    Virginie Fabre

    2011-01-01

    Full Text Available During later MOIS3, in Europe two populations were present, autochthonous Neanderthals and modern humans. Ecological competition between these two populations has often been evoked but never demonstrated. Our aim is to establish whether resource competition occurred. In this paper, in order to examine the possibility of ecological competition between these two populations, 599 isotopic data were subjected to rigorous statistical treatment and analysis through mixing models. The aim of this paper was to compare dietary strategies of Neanderthals and modern humans over time. Our conclusions suggest that Neanderthals and modern humans shared dietary habits in the particular environmental context of MOIS3 characterised in Europe by climatic deterioration. In this environmental context, the resource competition between Neanderthals and modern humans may have accelerated the disappearance of the Neanderthal population.

  9. Application of helium isotopes to studies of ocean circulation

    Science.gov (United States)

    Schlosser, P.; Newton, R.; Winckler, G.; Lupton, J.; Jenkins, W.; Top, Z.; Roether, W.; Jean-Baptiste, P.

    2004-12-01

    Since the discovery of excess He-3 in the ocean by Clarke and Craig in the 1960's helium isotopes have been used in local, regional and global studies of circulation patterns and water mass transformation in the world ocean. From initial pilot studies through systematic exploration of these tracers during the GEOSECS (Geochemical Ocean Sections) program to the recent global survey as part of the WOCE (World Ocean Circulation Experiment) hydrographic program (WHP) we obtained more detailed information on the distribution of helium isotopes, as well as their sources and sinks in the ocean. This information can now be applied to construct global fields of helium isotopes and to extract unique information on the circulation patterns at different depth levels in the ocean, as well as on local and regional processes such as ventilation of water masses in deep water formation regions. Additionally, the data sets are now sufficiently large to be useful for validation of Ocean General Circulation Models (OGCM's). In this contribution we present examples of global helium isotope fields constructed from major programs such as GEOCECS, TTO (Transient Tracers in the Ocean), SAVE (South Atlantic Ventilation Experiment) and WOCE, as well as from individual ocean sections. We use the data to delineate circulation patterns in the major ocean basins at several depth levels, especially mid-depth waters. Additionally, we outline the use of helium isotopes in studies of ocean ventilation. Finally, we compare observed and simulated helium isotope fields to highlight OGCM capabilities and deficiencies to reproduce internal He-3 excesses in the ocean and the related ventilation processes.

  10. Microbes: Agents of Isotopic Change

    Science.gov (United States)

    Fogel, M. L.

    2012-12-01

    Microbes drive many of the important oxidation and reduction reactions on Earth; digest almost all forms of organic matter; and can serve as both primary and secondary producers. Because of their versatile biochemistry and physiology, they impart unique isotopic signatures to organic and inorganic materials, which have proven to be key measurements for understanding elemental cycling now and throughout Earth's history. Understanding microbial isotope fractionations in laboratory experiments has been important for interpreting isotopic patterns measured in natural settings. In fact, the pairing of simple experiment with natural observation has been the pathway for interpreting the fingerprint of microbial processes in ancient sediments and rocks. Examples of how key experiments have explained stable isotope fractionations by microbes and advanced the field of microbial ecology will be presented. Learning the isotopic signatures of Earth's microbes is a valuable exercise for predicting what isotopic signatures could be displayed by possible extant or extinct extraterrestrial life. Given the potential for discovery on Mars, Enceladus, and other solar system bodies, new methods and techniques for pinpointing what is unique about microbial isotope signatures is particularly relevant.

  11. Compelling Research Opportunities using Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-04-23

    Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies and diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1

  12. Systematic review

    DEFF Research Database (Denmark)

    Enggaard, Helle

    Title: Systematic review a method to promote nursing students skills in Evidence Based Practice Background: Department of nursing educate students to practice Evidence Based Practice (EBP), where clinical decisions is based on the best available evidence, patient preference, clinical experience...... and resources available. In order to incorporate evidence in clinical decisions, nursing students need to learn how to transfer knowledge in order to utilize evidence in clinical decisions. The method of systematic review can be one approach to achieve this in nursing education. Method: As an associate lecturer...... I have taken a Comprehensive Systematic Review Training course provide by Center of Clinical Guidelines in Denmark and Jonna Briggs Institute (JBI) and practice in developing a systematic review on how patients with ischemic heart disease experiences peer support. This insight and experience...

  13. Isotope evidence for N2-fixation in Sphagnum peat bogs

    Science.gov (United States)

    Novak, Martin; Jackova, Ivana; Buzek, Frantisek; Stepanova, Marketa; Veselovsky, Frantisek; Curik, Jan; Prechova, Eva

    2016-04-01

    Waterlogged organic soils store as much as 30 % of the world's soil carbon (C), and 15 % of the world's soil nitrogen (N). In the era of climate change, wetlands are vulnerable to increasing temperatures and prolonged periods of low rainfall. Higher rates of microbial processes and/or changing availability of oxygen may lead to peat thinning and elevated emissions of greenhouse gases (mostly CO2, but also CH4 and N2O). Biogeochemical cycling of C and N in peat bogs is coupled. Under low levels of pollution by reactive nitrogen (NO3-, NH4+), increasing N inputs may positively affect C storage in peat. Recent studies in North America and Scandinavia have suggested that pristine bogs are characterized by significant rates of microbial N2 fixation that augments C storage in the peat substrate. We present a nitrogen isotope study aimed at corroborating these findings. We conducted an isotope inventory of N fluxes and pools at two Sphagnum-dominated ombrotrophic peat bogs in the Czech Republic (Central Europe). For the first time, we present a time-series of del15N values of atmospheric input at the same locations as del15N values of living Sphagnum and peat. The mean del15N values systematically increased in the order: input NH4+ (-10.0 ‰) NO3- (-7.9 ‰) < peat porewater (-5.6 ‰) < Sphagnum (-5.0 ‰) < shallow peat (-4.2 ‰) < deep peat (-2.2 ‰) < runoff (-1.4 ‰) < porewater N2O (1.4 ‰). Importantly, N of Sphagnum was isotopically heavier than N of the atmospheric input (p < 0.001). If partial incorporation of reactive N from the atmosphere into Sphagnum was isotopically selective, the residual N would have to be isotopically extremely light. Such N, however, was not identified anywhere in the ecosystem. Alternatively, Sphagnum may have contained an admixture of isotopically heavier N from atmospheric N2 (del15N N2 = 0 ‰). We conlude that the N isotope systematics at the two Czech sites is consistent with the concept of significant N2 fixation rates in

  14. Extreme heterogeneity in Sr isotope systematic in the Himalayan ...

    Indian Academy of Sciences (India)

    R. Narasimhan, Krishtel eMaging Solutions

    This depends on the geothermal gradient which in the present case is not in steady state. The relationships between some of the possi- ble solidus/melting curves together with transient geotherms (taken from figure 5(b)) are shown in figure 6. Let us first consider the relation between. H2O-saturated solidus curve for granite ...

  15. Early Disk dynamics Inferred from Isotope Systematics of Individual Chrondules

    DEFF Research Database (Denmark)

    Bollard, Jean Francois André

    indicates that chondrule formation started contemporaneously with CAIs and lasted ~3 Myr. However, this result is based on the analyses of only five individual chondrules and, thus, does not statistically evaluate the transient heating events. The principal goal of this project is to define a set...

  16. The early bird gets the shrimp: Confronting assumptions of isotopic equilibrium and homogeneity in a wild bird population

    Science.gov (United States)

    Wunder, Michael B.; Jehl, Joseph R.; Stricker, Craig A.

    2012-01-01

    1. Because stable isotope distributions in organic material vary systematically across energy gradients that exist in ecosystems, community and population structures, and in individual physiological systems, isotope values in animal tissues have helped address a broad range of questions in animal ecology. It follows that every tissue sample provides an isotopic profile that can be used to study dietary or movement histories of individual animals. Interpretations of these profiles depend on the assumption that metabolic pools are isotopically well mixed and in equilibrium with dietary resources prior to tissue synthesis, and they extend to the population level by assuming isotope profiles are identically distributed for animals using the same proximal dietary resource. As these assumptions are never fully met, studying structure in the variance of tissue isotope values from wild populations is informative. 2. We studied variation in δ13C, δ15N, δ2H and δ18O data for feathers from a population of eared grebes (Podiceps nigricollis) that migrate to Great Salt Lake each fall to moult feathers. During this time, they cannot fly and feed almost exclusively on superabundant brine shrimp (Artemia franciscana). The ecological simplicity of this situation minimized the usual spatial and trophic complexities often present in natural studies of feather isotope values. 3. Ranges and variances of isotope values for the feathers were larger than those from previously published studies that report feather isotopic variance, but they were bimodally distributed in all isotope dimensions. Isotope values for proximal dietary resources and local surface water show that some of the feathers we assumed to have been grown locally must have been grown before birds reached isotopic equilibrium with local diet or immediately prior to arrival at Great Salt Lake. 4. Our study provides novel insights about resource use strategies in eared grebes during migration. More generally, it

  17. The Molybdenum Isotope System as a Tracer of Slab Input in Subduction Zones: An Example From Martinique, Lesser Antilles Arc

    Science.gov (United States)

    Gaschnig, Richard M.; Reinhard, Christopher T.; Planavsky, Noah J.; Wang, Xiangli; Asael, Dan; Chauvel, Catherine

    2017-12-01

    Molybdenum isotopes are fractionated by Earth-surface processes and may provide a tracer for the recycling of crustal material into the mantle. Here, we examined the Mo isotope composition of arc lavas from Martinique in the Lesser Antilles arc, along with Cretaceous and Cenozoic Deep Sea Drilling Project sediments representing potential sedimentary inputs into the subduction zone. Mo stable isotope composition (defined as δ98Mo in ‰ deviation from the NIST 3134 standard) in lavas older than ˜7 million years (Ma) exhibits a narrow range similar to and slightly higher than MORB, whereas those younger than ˜7 Ma show a much greater range and extend to unusually low δ98Mo values. Sediments from DSDP Leg 78A, Site 543 have uniformly low δ98Mo values whereas Leg 14, Site 144 contains both sediments with isotopically light Mo and Mo-enriched black shales with isotopically heavy Mo. When coupled with published radiogenic isotope data, Mo isotope systematics of the lavas can be explained through binary mixing between a MORB-like end-member and different sedimentary compositions identified in the DSDP cores. The lavas older than ˜7 Ma were influenced by incorporation of isotopically heavy black shales into the mantle wedge. The younger lavas are the product of mixing isotopically light sedimentary material into the mantle wedge. The change in Mo isotope composition of the lavas at ˜7 Ma is interpreted to reflect the removal of the Cretaceous black shale component due to the arrival of younger ocean crust where the age-equivalent Cretaceous sediments were deposited in shallower oxic waters. Isotopic fractionation of Mo during its removal from the slab is not required to explain the observed systematics in this system.

  18. Isotope-based quantum information

    CERN Document Server

    G Plekhanov, Vladimir

    2012-01-01

    The present book provides to the main ideas and techniques of the rapid progressing field of quantum information and quantum computation using isotope - mixed materials. It starts with an introduction to the isotope physics and then describes of the isotope - based quantum information and quantum computation. The ability to manipulate and control electron and/or nucleus spin in semiconductor devices provides a new route to expand the capabilities of inorganic semiconductor-based electronics and to design innovative devices with potential application in quantum computing. One of the major challenges towards these objectives is to develop semiconductor-based systems and architectures in which the spatial distribution of spins and their properties can be controlled. For instance, to eliminate electron spin decoherence resulting from hyperfine interaction due to nuclear spin background, isotopically controlled devices are needed (i.e., nuclear spin-depleted). In other emerging concepts, the control of the spatial...

  19. Isotope Geochronology: Models Versus Reality

    National Research Council Canada - National Science Library

    Jan Burchart

    2015-01-01

    Majority of the papers on isotopic dating of minerals and rocks have been devoted to some new geochronological data important for geology or to developments of apparatus and improvements of laboratory...

  20. Radii and Binding Energies in Oxygen Isotopes: A Challenge for Nuclear Forces.

    Science.gov (United States)

    Lapoux, V; Somà, V; Barbieri, C; Hergert, H; Holt, J D; Stroberg, S R

    2016-07-29

    We present a systematic study of both nuclear radii and binding energies in (even) oxygen isotopes from the valley of stability to the neutron drip line. Both charge and matter radii are compared to state-of-the-art ab initio calculations along with binding energy systematics. Experimental matter radii are obtained through a complete evaluation of the available elastic proton scattering data of oxygen isotopes. We show that, in spite of a good reproduction of binding energies, ab initio calculations with conventional nuclear interactions derived within chiral effective field theory fail to provide a realistic description of charge and matter radii. A novel version of two- and three-nucleon forces leads to considerable improvement of the simultaneous description of the three observables for stable isotopes but shows deficiencies for the most neutron-rich systems. Thus, crucial challenges related to the development of nuclear interactions remain.

  1. Stable Chlorine Isotope Fractionation

    Science.gov (United States)

    Sharp, Z.

    2006-12-01

    Chlorine isotope partitioning between different phases is not well understood. Pore fluids can have δ37Cl values as low as -8‰, with neoform sediments having strongly positive values. Most strikingly, volcanic gases have δ37Cl values that cover a range in excess of 14‰ (Barnes et al., this meeting). The large range is difficult to explain in terms of equilibrium fractionation, which, although calculated to be very large for Cl in different oxidation states, should be less than 2‰ between chloride species (Schauble et al., 2003, GCA). To address the discrepancy between Nature and theory, we have measured Cl isotope fractionation for selected equilibrium and disequilibrium experiments in order to identify mechanisms that might lead to large fractionations. 1) NaCl (s,l) NaCl (v): NaCl was sealed in an evacuated silica tube and heated at one end, causing vaporization and reprecipitation of NaCl (v) at the cool end of the tube. The fractionation is 0.2‰ at 700°C (halite-vapor) and 0.7‰ at 800°C (liquid-vapor), respectively. The larger fractionation at higher temperature may be related to equilibrium fractionation between liquid and gas vs. `stripping' of the solid in the lower T experiments. 2) Sodalite NaCl(l): Nepheline and excess NaCl were sealed in a Pt crucible at 825°C for 48 hrs producing sodalite. The measured newly-formed sodalite-NaCl fractionation is -0.2‰. 3) Volatilization of HCl: Dry inert gas was bubbled through HCl solutions and the vapor was collected in a downstream water trap. There was no fractionation for 12.4M HCl (HCl fuming) vapor at 25°C. For a 1 M boiling HCl solution, the HCl-vapor fractionation was ~9‰. The difference is probably related to the degree of dissociation in the acid, with HCl dissolved in water for the highly acidic solutions, and dissociated H3O+ and Cl- for lower concentrations. The HCl volatilization experiments are in contrast to earlier vapor-liquid experiments in NaCl-H2O system, where fractionation was

  2. Single-molecule fluorescence autocorrelation experiments on pentacene : The dependence of intersystem crossing on isotopic composition

    NARCIS (Netherlands)

    Brouwer, A.C.J.; Köhler, J.; Oijen, A.M. van; Groenen, E.J.J.; Schmidt, J.

    1999-01-01

    Single pentacene molecules containing 13C or 1H in a pentacene-d14 doped p-terphenyl crystal have been studied by fluorescence autocorrelation. The triplet dynamics has been analyzed and a systematic dependence of the S1→T1 intersystem crossing rate on isotopic composition was found. This variation

  3. Ar isotope analysis for K-Ar dating using two modified-VG5400 mass spectrometers. 1. Isotope dilution method

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Keisuke; Ogata, Atsumi; Miura, Y.N.; Yamaguchi, Kenji [Okayama Univ., Misasa, Tottori (Japan). Inst. for Study of the Earth`s Interior

    1996-02-01

    Two noble gas mass spectrometry systems (MS-I and MS-II) have been installed in 1989, one of which was designed in our laboratory for Ar isotope analysis to measure K-Ar age by isotope dilution method using {sup 38}Ar-spike. The whole system was modified and improved to obtain high quality Ar data. The improved system composed of an Ar extraction and purification line and a Modified-VG5400 mass spectrometer enables us to determine precise Ar isotope composition easily and speedily irrespective to operator`s skillfulness. Formulas calculating radiogenic {sup 40}Ar abundance, which takes account of correction for Ar isotopes of both spike and blank, are presented. For samples with young K-Ar age, formulas to estimate the radiogenic {sup 40}Ar abundance based on {sup 40}Ar/{sup 36}Ar ratio are also proposed. Replicate analyses on many K-Ar standard samples show that the system can be applicable to samples with ages ranging 0.01 to 1500 Ma without any systematic analytical errors. (author).

  4. Study of polonium isotopes ground state properties by simultaneous atomic- and nuclear-spectroscopy

    CERN Multimedia

    Koester, U H; Kalaninova, Z; Imai, N

    2007-01-01

    We propose to systematically study the ground state properties of neutron deficient $^{192-200}$Po isotopes by means of in-source laser spectroscopy using the ISOLDE laser ion source coupled with nuclear spectroscopy at the detection setup as successfully done before by this collaboration with neutron deficient lead isotopes. The study of the change in mean square charge radii along the polonium isotope chain will give an insight into shape coexistence above the mid-shell N = 104 and above the closed shell Z = 82. The hyperfine structure of the odd isotopes will also allow determination of the nuclear spin and the magnetic moment of the ground state and of any identifiable isomer state. For this study, a standard UC$_{x}$ target with the ISOLDE RILIS is required for 38 shifts.

  5. Measurements of interaction cross sections for 22–35Na isotopes

    Directory of Open Access Journals (Sweden)

    Suzuki S.

    2014-03-01

    Full Text Available Interaction cross sections (σI for 22−35Na isotopes from the stability line to the vicinity of the neutron drip line have been measured at around 240 MeV/nucleon. The σI for 33−35Na were measured for the first time. Enhancement in cross sections is clearly observed from the systematics for stable nuclei, for isotopes with large mass numbers. From the known values of the nuclear-deformation parameters β2 of 22−31Na, these enhancement can be mainly ascribed to the nuclear deformation. Large enhancement in heavier isotopes suggest that these nuclei are strongly deformed. The root-mean-square (RMS nuclear matter radii were deduced from the σI by using Glauber-type calculation. Furthermore, a monotonic growth of the neutron-skin thickness has been deduced with increasing neutron number for Na isotopes.

  6. Laser fluorescence on radio-active isotopes produced in very low yield

    Science.gov (United States)

    Dancy, M. P.; Billowes, J.; Grant, I. S.; Evans, D. E.; Griffith, J. A. R.; Wells, S. A.; Eastham, D. A.; Groves, J.; Smith, J. R. H.; Tolfree, D. W. L.; Walker, P. M.

    1990-08-01

    East particle-photon coincidence techniques, developed at Daresbury with strontium isotopes, allow ultrasensitive laser fluorescence spectroscopy of beams of radio-active isotopes which can only be produced in very low yields. The technique has now been applied to neutron-deficient barium isotopes down to120Ba. From measured hyperfine splittings and isotope shifts, nuclear moments and changes in mean square radii have been determined. The work has revealed an abrupt increase in the mean square radius for121Ba large enough to disrupt the systematic staggering of nuclear size seen for the series. In a recent experiment an isomeric state of127Ba with a half-life of about 2 seconds has been produced in a very low yield; nevertheless we have succeeded in obtaining a fluorescence spectrum.

  7. Cu Isotopic Composition in Surface Environments and in Biological Systems: A Critical Review

    Directory of Open Access Journals (Sweden)

    Zhuhong Wang

    2017-05-01

    Full Text Available Copper (Cu is a transition metal and an essential micronutrient for organisms, but also one of the most widespread toxic inorganic contaminants at very high content. The research on Cu isotopes has grown rapidly in the last decade. Hitherto, a large number of studies have been published on the theoretical fractionation mechanisms, experimental data and natural variations of Cu isotopes in variable environments and ecosystems. These studies reported a large variation of δ65Cu (−16.49 to +20.04‰ in terrestrial samples and showed that Cu isotopes could be fractionated by various biogeochemical processes to different extent. Several papers have previously reviewed the coupling of Cu and Zn isotope systematics, and we give here a tentative review of the recent publications only on Cu isotopesin variable surface repositories, animals and human beings, with a goal to attract much attention to research on Cu (and other metals behaviors in the environment and biological systems.

  8. Cu Isotopic Composition in Surface Environments and in Biological Systems: A Critical Review.

    Science.gov (United States)

    Wang, Zhuhong; Chen, Jiubin; Zhang, Ting

    2017-05-18

    Copper (Cu) is a transition metal and an essential micronutrient for organisms, but also one of the most widespread toxic inorganic contaminants at very high content. The research on Cu isotopes has grown rapidly in the last decade. Hitherto, a large number of studies have been published on the theoretical fractionation mechanisms, experimental data and natural variations of Cu isotopes in variable environments and ecosystems. These studies reported a large variation of δ(65)Cu (-16.49 to +20.04‰) in terrestrial samples and showed that Cu isotopes could be fractionated by various biogeochemical processes to different extent. Several papers have previously reviewed the coupling of Cu and Zn isotope systematics, and we give here a tentative review of the recent publications only on Cu isotopesin variable surface repositories, animals and human beings, with a goal to attract much attention to research on Cu (and other metals) behaviors in the environment and biological systems.

  9. Isotope and ion selectivity in reverse osmosis desalination: geochemical tracers for man-made freshwater.

    Science.gov (United States)

    Kloppmann, Wolfram; Vengosh, Avner; Guerrot, Catherine; Millot, Romain; Pankratov, Irena

    2008-07-01

    A systematic measurement of ions and 2H/1H, 7Li/6Li, 11B/10B, 18O/ 16O, and 87Sr/86Sr isotopes in feed-waters, permeates, and brines from commercial reverse osmosis (RO) desalination plants in Israel (Ashkelon, Eilat, and Nitzana) and Cyprus (Larnaca) reveals distinctive geochemical and isotopic fingerprints of fresh water generated from desalination of seawater (SWRO) and brackish water (BWRO). The degree of isotope fractionation during the passage of water and solutes through the RO membranes depends on the medium (solvent-water vs. solutes), chemical speciation of the solutes, their charge, and their mass difference. O, H, and Sr isotopes are not fractionated during the RO process. 7Li is preferentially rejected in low pH RO, and B isotope fractionation depends on the pH conditions. Under low pH conditions, B isotopes are not significantly fractionated, whereas at high pH, RO permeates are enriched by 20 per thousand in 11B due to selective rejection of borate ion and preferential permeation of 11B-enriched boric acid through the membrane. The specific geochemical and isotopic fingerprints of SWRO provide a unique tool for tracing "man-made" fresh water as an emerging recharge component of natural water resources.

  10. The structural and decay properties of Francium isotopes

    Science.gov (United States)

    Bhuyan, M.; Mahapatro, S.; Singh, S. K.; Patra, S. K.

    2015-04-01

    We study the bulk properties such as binding energy (BE), root-mean-square (RMS) charge radius, quadrupole deformation etc. for Francium (Fr) isotopes having mass number A = 180-240 within the framework of relativistic mean field (RMF) theory. Systematic comparisons are made between the calculated results from RMF theory, Finite Range Droplet Model (FRDM) and the experimental data. Most of the nuclei in the isotopic chain shows prolate configuration in their ground state. The α-decay properties like α-decay energy and the decay half-life are also estimated for three different chains of 198Fr, 199Fr and 200Fr. The calculation for the decay half-life are carried out by taking two different empirical formulae and the results are compared with the experimental data.

  11. Iron isotope fractionation and the oxygen fugacity of the mantle.

    Science.gov (United States)

    Williams, Helen M; McCammon, Catherine A; Peslier, Anne H; Halliday, Alex N; Teutsch, Nadya; Levasseur, Sylvain; Burg, Jean-Pierre

    2004-06-11

    The oxygen fugacity of the mantle exerts a fundamental influence on mantle melting, volatile speciation, and the development of the atmosphere. However, its evolution through time is poorly understood. Changes in mantle oxidation state should be reflected in the Fe3+/Fe2+ of mantle minerals, and hence in stable iron isotope fractionation. Here it is shown that there are substantial (1.7 per mil) systematic variations in the iron isotope compositions (delta57/54Fe) of mantle spinels. Spinel delta57/54Fe values correlate with relative oxygen fugacity, Fe3+/sigmaFe, and chromium number, and provide a proxy of changes in mantle oxidation state, melting, and volatile recycling.

  12. Electron linac for medical isotope production with improved energy efficiency and isotope recovery

    Science.gov (United States)

    Noonan, John; Walters, Dean; Virgo, Matt; Lewellen, John

    2015-09-08

    A method and isotope linac system are provided for producing radio-isotopes and for recovering isotopes. The isotope linac is an energy recovery linac (ERL) with an electron beam being transmitted through an isotope-producing target. The electron beam energy is recollected and re-injected into an accelerating structure. The ERL provides improved efficiency with reduced power requirements and provides improved thermal management of an isotope target and an electron-to-x-ray converter.

  13. C-isotope composition of fossil sedges and grasses

    Science.gov (United States)

    Kurschner, Wolfram M.

    2010-05-01

    C4 plants differ from C3 plants regarding their anatomy and their C-isotope composition. Both features can be used in the geological record to determine the presence of C4 plants. Yet, the evolution of the C4 pathway in the fossil record is enigmatic as palaeobotanical and geological evidence for C4 plants is sparse. The oldest structural evidence for Kranz anatomy has been found in Late Miocene permineralized grass leaf remains. But studies on the C-isotope composition of sedimentary organic matter indicate that abundant C4 biomass was present in N-America and Asia throughout the Miocene in expanding savannahs and grasslands. The success of C4 plants appears to be related also to an increasing seasonal aridity in the tropical climate belts and the co-evolution of grazers. However, C- isotope composition of palaeosols or vertebrate teeth only allows to estimate the abundance of C4 plant biomass in the vegetation or in the diet without further taxonomical specification which plant groups would have had C4 metabolism. In this contribution the first extensive C-isotope analysis of fossil seeds of sedges and a few grasses are presented. The age of the carpological material ranges from Late Eocene to Pliocene and was collected from several central European brown coal deposits. The 52 different taxa studied include several species of Carex, Cladiocarya, Eriopherum, Eleocharis, Scirpus, Sparganium. Most of them representing herbaceous elements of a (sub)tropical vegetation growing near the edge of a lake. The C-isotope composition of the fossil seeds varies between -30 and -23 o/oo indicating C3 photosynthesis. This first systematic inventory shows that C4 plants were absent in the European (sub)tropical brown coal forming wetland vegetation during the Tertiary. These preliminary data are in agreement with phylogenetic studies which predict the origin of C4 plants outside the European realm.

  14. Chromium isotopic fractionation in aquatic systems and foraminiferal calcite

    Science.gov (United States)

    Wang, X.; Wu, W.; Reinhard, C. T.; Planavsky, N.

    2016-12-01

    The stable chromium (Cr) isotope system is an emerging proxy for studying the reduction/oxidation (redox) state of the early earth. However, the distribution and isotopic composition of Cr in many modern environments is still poorly known. For this reason, Cr isotope fractionation during biological processes, in rivers, estuaries, seawaters, and modern sediments need to be constrained to calibrate this potentially very useful paleoredox proxy. Here we report concentrations and isotope systematics of dissolved and suspended Cr in the Connecticut River system, and from core-top planktonic foraminiferal calcite from the global ocean. In the Connecticut River system, soil profile samples are unfractionated from bulk silicate Earth (BSE) values. River waters range from -0.2‰ to 0.9‰ (δ53Cr expressed as 53Cr/52Cr relative to NIST SRM 979 standard), with some, but not all tributaries showing seasonal differences. Suspended particulate samples range from -0.1 to 0‰ in autumn and from 0 to 0.1‰ in spring. Modern planktonic foraminifera show a wide range of δ53Cr values, from 0.2‰ to 2.2‰. Such variability seems to be controlled by both seawater heterogeneity and biological fractionation. In summary, weathering environments studied so far suggest wide variability of δ53Cr in rivers and weathered rocks, but with indiscernible correlation with climate types (temperate vs. tropical). In addition, large spatial variability has been detected in the modern seawater and large biological fractionation has been observed during marine biological calcification. These observations provide important guidelines for interpreting the ancient Cr isotope record.

  15. Isotope fractionation associated with the direct photolysis of 4-chloroaniline.

    Science.gov (United States)

    Ratti, Marco; Canonica, Silvio; McNeill, Kristopher; Erickson, Paul R; Bolotin, Jakov; Hofstetter, Thomas B

    2015-04-07

    Compound-specific isotope analysis is a useful approach to track transformations of many organic soil and water pollutants. Applications of CSIA to characterize photochemical processes, however, have hardly been explored. In this work, we systematically studied C and N isotope fractionation associated with the direct photolysis of 4-Cl-aniline used as a model compound for organic micropollutants that are known to degrade via photochemical processes. Laboratory experiments were carried out at an irradiation wavelength of 254 nm over the pH range 2.0 to 9.0 as well as in the presence of Cs(+) as a quencher of excited singlet 4-Cl-aniline at pH 7.0 and 9.0. We observed considerable variation of C and N isotope enrichment factors, ϵC and ϵN, between -1.2 ± 0.2‰ to -2.7 ± 0.2‰ for C and -0.6 ± 0.2‰ to -9.1 ± 1.6‰ for N, respectively, which could not be explained by the speciation of 4-Cl-aniline alone. In the presence of 1 M Cs(+), we found a marked increase of apparent (13)C-kinetic isotope effects ((13)C-AKIE) and decrease of 4-Cl-aniline fluorescence lifetimes. Our data suggest that variations of C and N isotope fractionation originate from heterolytic dechlorination of excited triplet and singlet states of 4-Cl-aniline. Linear correlations of (13)C-AKIE vs (15)N-AKIE were distinctly different for these two reaction pathways and may be explored further for the identification of photolytic aromatic dechlorination reactions.

  16. Isotope shifts in francium isotopes Fr-213206 and 221Fr

    Science.gov (United States)

    Collister, R.; Gwinner, G.; Tandecki, M.; Behr, J. A.; Pearson, M. R.; Zhang, J.; Orozco, L. A.; Aubin, S.; Gomez, E.; FrPNC Collaboration

    2014-11-01

    We present the isotope shifts of the 7 s1 /2 to 7 p1 /2 transition for francium isotopes 206 -213Fr with reference to 221Fr collected from two experimental periods. The shifts are measured on a sample of atoms prepared within a magneto-optical trap by a fast sweep of radio-frequency sidebands applied to a carrier laser. King plot analysis, which includes literature values for 7 s1 /2 to 7 p3 /2 isotope shifts, provides a field shift constant ratio of 1.0520(10) and a difference between the specific mass shift constants of 170(100) GHz amu between the D1 and D2 transitions, of sufficient precision to differentiate between ab initio calculations.

  17. Systematic review

    DEFF Research Database (Denmark)

    Lødrup, Anders Bergh; Reimer, Christina; Bytzer, Peter

    2013-01-01

    in getting off acid-suppressive medication and partly explain the increase in long-term use of PPI. A number of studies addressing this issue have been published recently. The authors aimed to systematically review the existing evidence of clinically relevant symptoms caused by acid rebound following PPI...

  18. Systematic review

    DEFF Research Database (Denmark)

    Bager, Palle; Chauhan, Usha; Greveson, Kay

    2017-01-01

    OBJECTIVE: Advice lines for patients with inflammatory bowel diseases (IBD) have been introduced internationally. However, only a few publications have described the advice line service and evaluated the efficiency of it with many results presented as conference posters. A systematic synthesis of...

  19. Can stable isotopes ride out the storms? The role of convection for water isotopes in models, records, and paleoaltimetry studies in the central Andes

    Science.gov (United States)

    Rohrmann, Alexander; Strecker, Manfred R.; Bookhagen, Bodo; Mulch, Andreas; Sachse, Dirk; Pingel, Heiko; Alonso, Ricardo N.; Schilgen, Taylor F.; Montero, Carolina

    2015-04-01

    Globally, changes in stable isotope ratios of oxygen and hydrogen (δ18O and δD) in the meteoric water cycle result from distillation and evaporation processes. Isotope fractionation occurs when air masses rise in elevation, cool, and reduce their water-vapor holding capacity with decreasing temperature. As such, d18O and dD values from a variety of sedimentary archives are often used to reconstruct changes in continental paleohydrology as well as paleoaltimetry of mountain ranges. Based on 234 stream-water samples, we demonstrate that areas experiencing deep convective storms in the eastern south-central Andes (22 - 28° S) do not show the commonly observed relationship between δ18O and δD with elevation. These convective storms arise from intermontane basins, where diurnal heating forces warm air masses upward, resulting in cloudbursts and raindrop evaporation. Especially at the boundary between the tropical and extra-tropical atmospheric circulation regimes where deep-convective storms are very common (~ 26° to 32° N and S), the impact of such storms may yield non-systematic stable isotope-elevation relationships as convection dominates over adiabatic lifting of air masses. Because convective storms can reduce or mask the depletion of heavy isotopes in precipitation as a function of elevation, linking modern or past topography to patterns of stable isotope proxy records can be compromised in mountainous regions, and atmospheric circulation models attempting to predict stable isotope patterns must have sufficiently high spatial resolution to capture the fractionation dynamics of convective cells. Rohrmann, A. et al. Can stable isotopes ride out the storms? The role of convection for water isotopes in models, records, and paleoaltimetry studies in the central Andes. Earth Planet. Sci. Lett. 407, 187-195 (2014).

  20. Systematic Measurements of the Bohr-Weisskopf Effect at ISOLDE

    CERN Multimedia

    2002-01-01

    Nuclear electric and magnetic structure properties are measurable by high-resolution atomic spectroscopy through isotope shifts and the Bohr-Weisskopf effect (hyperfine structure anomalies). \\\\ \\\\ The greatest value of these measurements is when made systematically over a large number of isotopes. This has been done in the case of isotopes shifts most extensively by the experiment at ISOLDE. To date the magnetic distribution studies are few and isolated. Here we propose to intitiate a program at ISOLDE to measure hfs anomalies systematically. The experiments, requiring high-precision data on magnetic dipole constants as well as on nuclear g-factors, will be done by atomic-beam magnetic resonance with the use of laser excitation for polarization of the beam and a sixpole magnet acting as an analyser. \\\\ \\\\ The heavy alkali elements are the most promising candidates for hfs anomaly studies because of the large effect expected, the high production yields at ISOLDE and most importantly, the interesting variations...

  1. Isotopes a very short introduction

    CERN Document Server

    Ellam, Rob

    2016-01-01

    An isotope is a variant form of a chemical element, containing a different number of neutrons in its nucleus. Most elements exist as several isotopes. Many are stable while others are radioactive, and some may only exist fleetingly before decaying into other elements. In this Very Short Introduction, Rob Ellam explains how isotopes have proved enormously important across all the sciences and in archaeology. Radioactive isotopes may be familiar from their use in nuclear weapons, nuclear power, and in medicine, as well as in carbon dating. They have been central to establishing the age of the Earth and the origins of the solar system. Combining previous and new research, Ellam provides an overview of the nature of stable and radioactive isotopes, and considers their wide range of modern applications. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subjec...

  2. Geochemical and iron isotopic insights into hydrothermal iron oxyhydroxide deposit formation at Loihi Seamount

    Science.gov (United States)

    Rouxel, Olivier; Toner, Brandy; Germain, Yoan; Glazer, Brian

    2018-01-01

    Low-temperature hydrothermal vents, such as those encountered at Loihi Seamount, harbor abundant microbial communities and provide ideal systems to test hypotheses on biotic versus abiotic formation of hydrous ferric oxide (FeOx) deposits at the seafloor. Hydrothermal activity at Loihi Seamount produces abundant microbial mats associated with rust-colored FeOx deposits and variably encrusted with Mn-oxyhydroxides. Here, we applied Fe isotope systematics together with major and trace element geochemistry to study the formation mechanisms and preservation of such mineralized microbial mats. Iron isotope composition of warm (aged or less active deposits. These results are consistent with Fe(II) oxidation mediated by microbial processes considering the expected slow kinetics of abiotic Fe oxidation in low oxygen bottom water at Loihi Seamount. In contrast, FeOx deposits recovered at extinct sites have distinctly negative Fe-isotope values down to -1.77‰ together with significant enrichment in Mn and occurrence of negative Ce anomalies. These results are best explained by the near-complete oxidation of an isotopically light Fe(II) source produced during the waning stage of hydrothermal activity under more oxidizing conditions. Light Fe isotope values of FeOx are therefore generated by subsurface precipitation of isotopically heavy Fe-oxides rather than by the activity of dissimilatory Fe reduction in the subsurface. Overall, Fe-isotope compositions of microbial mats at Loihi Seamount display a remarkable range between -1.2‰ and +1.6‰ which indicate that Fe isotope compositions of hydrothermal Fe-oxide precipitates are particularly sensitive to local environmental conditions where they form, and are less sensitive to abiotic versus biotic origins. It follows that FeOx deposits at Loihi Seamount provides important modern analogues for ancient seafloor Fe-rich deposits allowing for testing hypotheses about the biogeochemical cycling of Fe isotopes on early Earth.

  3. Gross Properties and Isotopic Phenomena in Spectator Fragmentation

    Science.gov (United States)

    Sfienti, C.; De Napoli, M.; Adrich, P.; Aumann, T.; Bacri, C. O.; Barczyk, T.; Bassini, R.; Bianchin, S.; Boiano, C.; Botvina, A. S.; Boudard, A.; Brzychczyk, J.; Chbihi, A.; Cibor, J.; Czech, B.; Ducret, J.-E.; Emling, H.; Frankland, J.; Hellström, M.; Henzlova, D.; Kezzar, K.; Immé, G.; Iori, I.; Johansson, H.; Lafriakh, A.; Le Fèvre, A.; Le Gentil, E.; Leifels, Y.; Lynch, W. G.; Lühning, J.; Łukasik, J.; Lynen, U.; Majka, Z.; Mocko, M.; Müller, W. F. J.; Mykulyak, A.; Orth, H.; Otte, A. N.; Palit, R.; Pawlowski, P.; Pullia, A.; Raciti, G.; Rapisarda, E.; Sann, H.; Schwarz, C.; Simon, H.; Sümmerer, K.; Trautmann, W.; Volant, C.; Wallace, M.; Weick, H.; Wiechula, J.; Wieloch, A.; Zwieglinski, B.

    2007-05-01

    A systematic study of isotopic effects in the break-up of projectile spectators at relativistic energies has been performed with the ALADiN spectrometer at the GSI laboratory. Searching for signals of criticality in the fragment production we have applied the model-independent universal fluctuations theory already proposed to track criticality signals in multifragmentation to our data. The fluctuation of the largest fragment charge and of the asymmetry of the two and three largest fragments and their bimodal distribution have also been analysed.

  4. Non-linear Isotope Effects

    DEFF Research Database (Denmark)

    Schmidt, Johan Albrecht

    The isotopic fractionation associated with photodissociation of N2O, OCS and CO2, at different altitudes in Earth’s atmosphere, is investigated theoretically using constructed quantum mechanical models of the dissociation processes (i.e. potential energy surfaces and relevant coupling elements......’s stratosphere is nearly mass dependent, and only a small fraction of the observed anomalous oxygen-17 excess can be attributed to N2O photolysis. In contrast, stratospheric photolysis produces a significant inverse clumped isotope effect.(ii) Stratospheric OCS photolysis significantly enrich the remaining OCS...... in heavy carbon. The sulfur fractionation is weak and photolysis of OCS in the stratosphere produces only a small and mass dependent enrichment of heavy sulfur isotopes in the remaining OCS. Sulfur fractionation from the two remaining chemical sinks (oxidation by O(3P) and OH, respectively) is weak...

  5. Isotope specific arbitrary material sorter

    Science.gov (United States)

    Barty, Christopher P.J.

    2015-12-08

    A laser-based mono-energetic gamma-ray source is used to provide a rapid and unique, isotope specific method for sorting materials. The objects to be sorted are passed on a conveyor in front of a MEGa-ray beam which has been tuned to the nuclear resonance fluorescence transition of the desired material. As the material containing the desired isotope traverses the beam, a reduction in the transmitted MEGa-ray beam occurs. Alternately, the laser-based mono-energetic gamma-ray source is used to provide non-destructive and non-intrusive, quantitative determination of the absolute amount of a specific isotope contained within pipe as part of a moving fluid or quasi-fluid material stream.

  6. Excitation functions and isotopic effects in (n, p) reactions for stable nickel isotopes from reaction threshold to 20 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Lalremruata, B. [Department of Physics, University of Pune, Ganeshkhind, Pune-411007, Maharashtra (India)], E-mail: marema@physics.unipune.ernet.in; Ganesan, S. [Reactor Physics Design Division, BARC, Mumbai 58 (India); Bhoraskar, V.N. [Department of Physics, University of Pune, Ganeshkhind, Pune-411007, Maharashtra (India)], E-mail: vnb@physics.unipune.ernet; Dhole, S.D. [Department of Physics, University of Pune, Ganeshkhind, Pune-411007, Maharashtra (India)], E-mail: sanjay@physics.unipune.ernet.in

    2009-05-01

    The excitation function for (n, p) reactions from reaction threshold to 20 MeV on five nickel isotopes viz; {sup 58}Ni, {sup 60}Ni, {sup 61}Ni, {sup 62}Ni and {sup 64}Ni were calculated using Talys-1.0 nuclear model code involving the fixed set of global parameters. A good agreement between the calculated and measured data is obtained with minimum effort on parameter fitting and only one free parameter called 'Shell damping factor'. This is of importance to the validation of nuclear model approaches with increased predictive power. The systematic decrease in (n, p) cross-sections with increasing neutron number in reactions induced by neutrons on isotopes of nickel is explained in terms of the proton separation energy and the pre-equilibrium model. The compound nucleus and pre-equilibrium reaction mechanism as well as the isotopic effects were also studied.

  7. Cosmology: Rare isotopic insight into the Universe

    Science.gov (United States)

    Prantzos, Nikos

    2016-01-01

    Light isotopes of hydrogen and helium formed minutes after the Big Bang. The study of one of these primordial isotopes, helium-3, has now been proposed as a useful strategy for constraining the physics of the standard cosmological model.

  8. Systematic Avocating

    Directory of Open Access Journals (Sweden)

    Jan Green

    2014-12-01

    Full Text Available Feeling obliged to undertake complex research tasks outside core working hours is a common occurrence in academia. Detailed and timely research projects are expected; the creation and defence of sufficient intervals within a crowded working schedule is one concern explored in this short version paper. Merely working longer hours fails to provide a satisfactory solution for individuals experiencing concerns of this nature. Personal effort and drive are utilised and requires the application of mental mustering and systematic procedures. The attitude to research work is treating the task as a hobby conceptualised as avocating. Whilst this provides a personal solution through immersion in the task, this approach should raise concerns for employers. The flexibility of grounded theory is evident and the freedom to draw on various bodies of knowledge provides fresh insight into a problem that occurs in organizations in many sectors experiencing multiple priorities. The application of the core category, systematic avocating, may prove beneficial.

  9. Evaluating the utility of hydrocarbons for Re-Os geochronology : establishing the timing of processes in petroleum ore systems

    Energy Technology Data Exchange (ETDEWEB)

    Selby, D.; Creaser, R.A. [Alberta Univ., Edmonton, AB (Canada). Dept. of Earth and Atmospheric Sciences

    2005-07-01

    Oil from 6 Alberta oil sands deposits were analyzed with a rhenium-osmium (Re-Os) isotope chronometer, an emerging tool for determining valuable age information on the timing of petroleum generation and migration. The tool uses molybdenite and other sulphide minerals to establish the timing and duration of mineralization. However, establishing the timing events of petroleum systems can be problematic because viable sulphides for the Re-Os chronometer are often not available. Therefore, the known presence of Re and Os associated with organic matter in black shale, a common source of hydrocarbons, may suggest that bitumen and petroleum common to petroleum systems may be utilised for Re-Os geochronology. This study evaluated the potential of the Re-Os isotopic system for geochronology and as an isotopic tracer for hydrocarbon systems. The evaluation was based on Re-Os isotopic analyses of bitumen and oil sands. Hydrocarbons formed from migrated oil in both Alberta oil sand deposits and a Paleozoic Mississippi Valley-type lead-zinc deposit contain significant Re and Os contents with high {sup 187}Re/{sup 188}Os and radiogenic {sup 187}Os/{sup 188}Os ratios suitable for geochronology. The oil from the 6 Alberta oil sand deposits yields Re-Os analyses with very high Re/{sup 188}Os ratios, and radiogenic Os isotopic compositions. Regression of the Re-Os data yields a date of 116 {+-} 27 Ma. This date plausibly represents the period of in situ radiogenic growth of {sup 187}Os following hydrocarbon migration and reservoir filling. Therefore, directly dating these processes, and this formation age corresponds with recent burial history models for parts of the Western Canada Sedimentary Basin. The very high initial {sup 187}Os/{sup 188}Os for this regression requires rocks much older than Cretaceous for the hydrocarbon source.

  10. Developmentand Application of Accelerator Isotopes in China

    OpenAIRE

    YANG Yuan-you; LI Fei-ze; LIAO Jia-li; Liu, Ning

    2015-01-01

    Compared with the isotopes generated by nuclear reactor, the isotopes prepared by accelerator always show high specific activity and short half-life period. And most of such isotopes always were neutron-deficient nuclides, giving β+ or single energy γ ray. As one of the most important methods preparing radionuclides, the preparation of isotopes by accelerator has attracted more and more attention from the beginning of 21th century. The development of the preparation and application of the acc...

  11. Coupled Mo-U abundances and isotopes in a small marine euxinic basin: Constraints on processes in euxinic basins

    Science.gov (United States)

    Bura-Nakić, Elvira; Andersen, Morten B.; Archer, Corey; de Souza, Gregory F.; Marguš, Marija; Vance, Derek

    2018-02-01

    Sedimentary molybdenum (Mo) and uranium (U) abundances, as well as their isotope systematics, are used to reconstruct the evolution of the oxygenation state of the surface Earth from the geological record. Their utility in this endeavour must be underpinned by a thorough understanding of their behaviour in modern settings. In this study, Mo-U concentrations and their isotope compositions were measured in the water column, sinking particles, sediments and pore waters of the marine euxinic Lake Rogoznica (Adriatic Sea, Croatia) over a two year period, with the aim of shedding light on the specific processes that control Mo-U accumulation and isotope fractionations in anoxic sediment. Lake Rogoznica is a 15 m deep stratified sea-lake that is anoxic and euxinic at depth. The deep euxinic part of the lake generally shows Mo depletions consistent with near-quantitative Mo removal and uptake into sediments, with Mo isotope compositions close to the oceanic composition. The data also, however, show evidence for periodic additions of isotopically light Mo to the lake waters, possibly released from authigenic precipitates formed in the upper oxic layer and subsequently processed through the euxinic layer. The data also show evidence for a small isotopic offset (∼0.3‰ on 98Mo/95Mo) between particulate and dissolved Mo, even at highest sulfide concentrations, suggesting minor Mo isotope fractionation during uptake into euxinic sediments. Uranium concentrations decrease towards the bottom of the lake, where it also becomes isotopically lighter. The U systematics in the lake show clear evidence for a dominant U removal mechanism via diffusion into, and precipitation in, euxinic sediments, though the diffusion profile is mixed away under conditions of increased density stratification between an upper oxic and lower anoxic layer. The U diffusion-driven precipitation is best described with an effective 238U/235U fractionation of +0.6‰, in line with other studied euxinic

  12. Stable isotopes and biomarkers in microbial ecology

    NARCIS (Netherlands)

    Boschker, H.T.S.; Middelburg, J.J.

    2002-01-01

    The use of biomarkers in combination with stable isotope analysis is a new approach in microbial ecology and a number of papers on a variety of subjects have appeared. We will first discuss the techniques for analysing stable isotopes in biomarkers, primarily gas chromatography-combustion-isotope

  13. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    In the first part of this series, we discussed how isotopes can be used as markers to determine the nature of intermediates in chemical reactions. The second part covered the effect of isotopes on equilibria and reactions, in processes where the bond to the isotopic a tom is broken. We showed with specific examples how.

  14. Systematic comparison of δ13C measurements of testosterone and derivative steroids in a freeze-dried urine candidate reference material for sports drug testing by gas chromatography/combustion/isotope ratio mass spectrometry and uncertainty evaluation using four different metrological approaches.

    Science.gov (United States)

    Munton, Ellaine; Murby, John; Hibbert, D Brynn; Santamaria-Fernandez, Rebeca

    2011-06-15

    An alternative calibration procedure for use when performing carbon isotope ratio measurements by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) has been developed. This calibration procedure does not rely on the corrections in-built in the instrument software, as the carbon isotope ratios of a sample are calculated from the measured raw peak areas. The method was developed for the certification of a urine reference material for sports drug testing, as the estimation of measurement uncertainty is greatly simplified. To ensure that the method is free from bias arising from the choice of calibration material and instrument, the carbon isotope ratios of steroids in urine extracts were measured using two different instruments in different laboratories, and three different reference materials (CU/USADA steroid standards from Brenna Laboratory, Cornell University; NIST RM8539 mineral oil; methane calibrated against NIST RM8560 natural gas). The measurements were performed at LGC and the Australian National Measurement Institute (NMI). It was found that there was no significant difference in measurement results when different instruments and reference materials were used to measure the carbon isotope ratio of the major testosterone metabolites androsterone and etiocholanolone, or the endogenous reference compounds pregnanediol, 11- ketoetiocholanolone and 11β-hydroxyandrosterone. Expanded measurement uncertainties at the 95% coverage probability ranged from 0.21‰ to 1.4‰, depending on analyte, instrument and reference material. The measurement results of this comparison were used to estimate a measurement uncertainty of δ(13)C for the certification of the urine reference material being performed on a single instrument using a single reference material at NMI. Copyright © 2011 John Wiley & Sons, Ltd.

  15. Alpha decay studies of new neutron-deficient francium isotopes and their daughters

    CERN Document Server

    Ewan, G T; Jonson, B; Mattsson, M; Tidemand-Petersson, P

    1980-01-01

    Neutron-deficient francium isotopes were produced by proton-induced spallation reactions and investigated by alpha spectroscopy following on-line mass separation. The new isotopes /sup 202,202/Fr were identified and their half-lives measured. An improved value for the half-life of /sup 203/Fr was obtained. Alpha branching ratios were determined for /sup 198m, g,199/At. The derivation of the mass excess of /sup 202/Fr and the systematics of alpha energies and reduced widths are discussed. (17 refs).

  16. First measurement of beta decay half-lives in neutron-rich Tl and Bi isotopes

    Science.gov (United States)

    Benzoni, G.; Morales, A. I.; Valiente-Dobón, J. J.; Gottardo, A.; Bracco, A.; Camera, F.; Crespi, F. C. L.; Corsi, A. M.; Leoni, S.; Million, B.; Nicolini, R.; Wieland, O.; Gadea, A.; Lunardi, S.; Boutachkov, P.; Bruce, A. M.; Górska, M.; Grebosz, J.; Pietri, S.; Podolyak, Zs.; Pfützner, M.; Regan, P. H.; Weick, H.; Alcántara Núñez, J.; Algora, A.; Al-Dahan, N.; de Angelis, G.; Ayyad, Y.; Alkhomashi, N.; Allegro, P. R. P.; Bazzacco, D.; Benlliure, J.; Bowry, M.; Bunce, M.; Casarejos, E.; Cortes, M. L.; Denis Bacelar, A. M.; Deo, A. Y.; Domingo-Pardo, C.; Doncel, M.; Dombradi, Zs.; Engert, T.; Eppinger, K.; Farrelly, G. F.; Farinon, F.; Farnea, E.; Geissel, H.; Gerl, J.; Goel, N.; Gregor, E.; Habermann, T.; Hoischen, R.; Janik, R.; Klupp, S.; Kojouharov, I.; Kurz, N.; Mandal, S.; Menegazzo, R.; Mengoni, D.; Napoli, D. R.; Naqvi, F.; Nociforo, C.; Prochazka, A.; Prokopowicz, W.; Recchia, F.; Ribas, R. V.; Reed, M. W.; Rudolph, D.; Sahin, E.; Schaffner, H.; Sharma, A.; Sitar, B.; Siwal, D.; Steiger, K.; Strmen, P.; Swan, T. P. D.; Szarka, I.; Ur, C. A.; Walker, P. M.; Wollersheim, H.-J.

    2012-09-01

    Neutron-rich isotopes around lead, beyond N = 126, have been studied exploiting the fragmentation of an uranium primary beam at the FRS-RISING setup at GSI. For the first time β-decay half-lives of 219Bi and 211,212,213Tl isotopes have been derived. The half-lives have been extracted using a numerical simulation developed for experiments in high-background conditions. Comparison with state of the art models used in r-process calculations is given, showing a systematic underestimation of the experimental values, at variance from close-lying nuclei.

  17. Development of a new method for hydrogen isotope analysis of trace hydrocarbons in natural gas samples

    Directory of Open Access Journals (Sweden)

    Xibin Wang

    2016-12-01

    Full Text Available A new method had been developed for the analysis of hydrogen isotopic composition of trace hydrocarbons in natural gas samples by using solid phase microextraction (SPME combined with gas chromatography-isotope ratio mass spectrometry (GC/IRMS. In this study, the SPME technique had been initially introduced to achieve the enrichment of trace content of hydrocarbons with low abundance and coupled to GC/IRMS for hydrogen isotopic analysis. The main parameters, including the equilibration time, extraction temperature, and the fiber type, were systematically optimized. The results not only demonstrated that high extraction yield was true but also shows that the hydrogen isotopic fractionation was not observed during the extraction process, when the SPME device fitted with polydimethylsiloxane/divinylbenzene/carbon molecular sieve (PDMS/DVB/CAR fiber. The applications of SPME-GC/IRMS method were evaluated by using natural gas samples collected from different sedimentary basins; the standard deviation (SD was better than 4‰ for reproducible measurements; and also, the hydrogen isotope values from C1 to C9 can be obtained with satisfying repeatability. The SPME-GC/IRMS method fitted with PDMS/DVB/CAR fiber is well suited for the preconcentration of trace hydrocarbons, and provides a reliable hydrogen isotopic analysis for trace hydrocarbons in natural gas samples.

  18. Sr isotopes and U series radionuclides in the Sangemini area (Central Italy: Hydrogeology implications

    Directory of Open Access Journals (Sweden)

    Maurizio Barbieri

    2014-06-01

    Full Text Available The strontium isotopic ratio (expressed as 87Sr/86Sr of groundwater represents a useful method for studying and understanding the groundwater circulations, also, the U and Ra isotopic compositions can vary as function of the groundwater residence time. This paper reports an evaluation of the probable recharge area of the Sangemini mineral water springs (Terni-Umbria Central Italy and an estimate of the residence time of the aquifer by coupling Sr and U series isotopic systematics. For this study have been analyzed four water sample for the isotope ratio of 87Sr/86Sr, and eleven samples, shallow waters and groundwaters, for U and Ra, furthermore were determined the values of isotopic ratio for sample of typical rocks of the area. The results of this study allow to identify: a recharge area in a restricted sector of the Meso-Cenozoic carbonates a longer and more effective water/rock interaction in the Quaternary series. U and Ra recoil models allow to estimate a groundwater residence time of about 350 years and a total water volume whose value (64*106 m3 agrees with the limited extension of the aquifer. The extension of the aquifer was constrained by comparing Sr isotopic composition of waters and local geological formations. Groundwaters seem mainly to circulate in clayey sandy Quaternary series characterized by low redox conditions.

  19. Fragmentation of exotic oxygen isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Leistenschneider, A.; Elze, Th.W.; Gruenschloss, A.; Palit, R. [Johann Wolfgang Goethe-Univ., Frankfurt (Germany). Inst. fuer Kernphysik; Aumann, T.; Cortina, D.; Datta Pramanik, U.; Emling, H.; Geissel, H.; Helariutta, K.; Hellstroem, M.; Ilievski, S.; Jones, K.; Muenzenberg, G.; Scheidenberger, C.; Schmidt, K.-H.; Suemmerer, K. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Boretzky, K.; Kratz, J.V.; Le Hong, Khiem [Johannes Gutenberg-Univ., Mainz (Germany). Inst. fue Kernchemie; Canto, L.F. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Carlson, B.V. [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil). Inst. Tecnologico de Aeronautica (ITA). Dept. de Fisica; Hussein, M.S. [Sao Paulo Univ. (USP), SP (Brazil). Inst. de Fisica; Kulessa, R.; Lubkiewicz, E.; Wajda, E.; Walus, W. [Uniwersytet Jagellonski, Krakow (Poland). Instytut Fizyki; Reiter, P. [Ludwig-Maximilians-Univ., Garching (Germany). Sektion Physik; Simon, H. [Technische Univ., Darmstadt (Germany). Inst. fuer Kernphysik

    2003-06-01

    Abrasion-ablation models and the empirical EPAX parametrization of projectile fragmentation are described. Their cross section predictions are compared to recent data of the fragmentation of secondary beams of neutron-rich, unstable {sup 19,20,21} O isotopes at beam energies near 600 MeV/nucleon as well as data for stable {sup 17,18} O beams. (author)

  20. Isotope Harvesting Opportunities at FRIB

    Science.gov (United States)

    Morrissey, David

    2017-01-01

    The fragmentation of fast heavy ion beams now at the National Superconducting Cyclotron Laboratory (NSCL) and in the future at the Facility for Rare Isotope Beams (FRIB) under construction produce an unprecedentedly broad spectrum of radionuclides but only a small fraction are used in the on-line rare-isotope program. Projectile fragmentation facilities provide an electromagnetically purified beam of a single projectile fragment for nuclear physics experiments ranging from low energy astrophysics, through nuclear structure studies, to probing fundamental symmetries. By augmenting the NSCL and FRIB production facilities with complimentary collection and purification of discarded ions, called isotope harvesting with chemical purification, many other nuclides will become available for off-line experiments in parallel with the primary experiment. A growing user community has established a list of key target isotopes and is working with the FRIB design team to allow inclusion of necessary equipment in the future. An overview of the possibilities and the techniques will be presented in this talk. Supported by Office of Science, US DOE and Michigan State University.

  1. Charge radii of radium isotopes

    NARCIS (Netherlands)

    Wansbeek, L. W.; Schlesser, S.; Sahoo, B. K.; Dieperink, A. E. L.; Onderwater, C. J. G.; Timmermans, R. G. E.

    2012-01-01

    We present a combined analysis of the available isotope-shift data from the optical spectra of Ra atoms and Ra+ ions. Atomic structure calculations of the field-shift and specific mass-shift constants of the low-lying levels in Ra+ are used. The nuclear radial differences delta for the radium

  2. Prospects for improved understanding of isotopic reactor antineutrino fluxes

    Science.gov (United States)

    Gebre, Y.; Littlejohn, B. R.; Surukuchi, P. T.

    2018-01-01

    Predictions of antineutrino fluxes produced by fission isotopes in a nuclear reactor have recently received increased scrutiny due to observed differences in predicted and measured inverse beta decay (IBD) yields, referred to as the "reactor antineutrino flux anomaly." In this paper, global fits are applied to existing IBD yield measurements to produce constraints on antineutrino production by individual plutonium and uranium fission isotopes. We find that fits including measurements from highly U 235 -enriched cores and fits including Daya Bay's new fuel evolution result produce discrepant best-fit IBD yields for U 235 and Pu 239 . This discrepancy can be alleviated in a global analysis of all data sets through simultaneous fitting of Pu 239 , U 235 , and U 238 yields. The measured IBD yield of U 238 in this analysis is (7.02 ±1.65 )×10-43 cm2/fission , nearly two standard deviations below existing predictions. Future hypothetical IBD yield measurements by short-baseline reactor experiments are examined to determine their possible impact on the global understanding of isotopic IBD yields. It is found that future improved short-baseline IBD yield measurements at both high-enriched and low-enriched cores can significantly improve constraints for U 235 , U 238 , and Pu 239 , providing comparable or superior precision to existing conversion- and summation-based antineutrino flux predictions. Systematic and experimental requirements for these future measurements are also investigated.

  3. Modeling equilibrium Fe isotope fractionation

    Science.gov (United States)

    Anbar, A.; Jarzecki, A.; Spiro, T.

    2003-04-01

    Research into the stable isotope biogeochemistry of Fe and other transition metals has been driven primarily by analytical innovations which have revealed significant isotope effects in nature and the laboratory. Further development of these new isotope systems requires complementary theoretical research to guide analytical efforts. The results of the first such studies show some discrepancies with experiments. For example, Johnson et al. (2002) report an experimentally-determined 56Fe/54Fe equilibrium fractionation factor between Fe(II) and Fe(III) aquo complexes of ˜1.0025. This effect is ˜50% smaller than predicted theoretically by Schauble et al. (2001). It is important to resolve such discrepancies. Equilibrium isotope fractionation factors can be predicted from vibrational spectroscopic data of isotopically-substituted complexes, or from theoretical predictions of some or all of these frequencies obtained using force field models. The pioneering work of Schauble et al. (2001) utilized a modified Urey-Bradley force field (MUBFF) model. This approach is limiting in at least three ways: First, it is not ab initio, requiring as input some measured vibrational frequencies. Such data are not always available, or may have significant uncertainties. Second, the MUBFF does not include potentially important effects of solvent interaction. Third, because it makes certain assumptions about molecular symmetry, the MUBFF-based approach is not able to model the spectra of mixed-ligand complexes. To address these limitations, we are evaluating the use of density functional theory (DFT) as an ab initio method to predict vibrational frequencies of isotopically-substituted complexes and, hence, equilibrium fractionation factors. In a preliminary examination of the frequency shift upon isotope substitution of the bending and asymmetric stretching modes of the tetrahedral FeCl_42- complex, we find substantial differences between MUBFF and DFT predictions. Results for other Fe

  4. The isotopic contamination in electromagnetic isotope separators; La contagion isotopique dans les separateurs electromagnetiques d'isotopes

    Energy Technology Data Exchange (ETDEWEB)

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

    1959-07-01

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

  5. Isotopic Compositions of the Elements 1989

    Science.gov (United States)

    De Laeter, J. R.; Heumann, K. G.; Rosman, K. J. R.

    1991-11-01

    The Subcommittee for Isotopic Abundance Measurements (SIAM) of the IUPAC Commission on Atomic Weights and Isotopic Abundances has carried out its biennial review of isotopic compositions, as determined by mass spectrometry and other relevant methods. The Subcommittee's critical evaluation of the published literature element by element forms the basis of the Table of Isotopic Compositions of the Elements as Determined by Mass Spectrometry 1989, which is presented in this Report. Atomic Weights calculated from the tabulated isotopic abundances are consistent with Ar(E) values listed in the Table of Standard Atomic Weights 1989.

  6. Stable isotope compounds - production, detection, and application.

    Science.gov (United States)

    Zachleder, Vilém; Vítová, Milada; Hlavová, Monika; Moudříková, Šárka; Mojzeš, Peter; Heumann, Hermann; Becher, Johannes R; Bišová, Kateřina

    2018-01-19

    Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies. Copyright © 2018. Published by Elsevier Inc.

  7. Modelling stable water isotopes: Status and perspectives

    Directory of Open Access Journals (Sweden)

    Werner M.

    2010-12-01

    Full Text Available Modelling of stable water isotopes H2 18O and HDO within various parts of the Earth’s hydrological cycle has clearly improved our understanding of the interplay between climatic variations and related isotope fractionation processes. In this article key principles and major research results of stable water isotope modelling studies are described. Emphasis is put on research work using explicit isotope diagnostics within general circulation models as this highly complex model setup bears many resemblances with studies using simpler isotope modelling approaches.

  8. Isotope record of environmental changes at the Skaliska Basin during the Late Glacial and Holocene

    Directory of Open Access Journals (Sweden)

    Mirosław-Grabowska Joanna

    2013-06-01

    Full Text Available The results of isotopic investigations of the Skaliska Basin sediments are presented. Stable isotope analyses were done for authigenic carbonates from three profiles: W1 - Piotrowo-Ławniki, W2 - Sąkieły Małe, and W4 - Budzewo. The profiles contain carbonate silts at the bottom, then calcareous detritus gyttja and organic silts and peat at the top. Palynological data indicate that sediment were accumulated in the Skaliska Basin from the final phase of the Younger Dryas to the Subboreal period. The values δ18O change from ca −9.4 to −4.5‰, and δ13C values varies from −5.1 to +0.1‰. Such a large range of isotopic data reflects changing conditions in the basin during accumulation of deposits (different water levels, water temperatures, and bioproduction. Based on the results of stable isotope analyses of the carbonates, isotopic zones (Is were defined and characterized for each profile. The results of isotopic analysis enabled reconstruction of varying environmental conditions connected with lake deepening and/or influx of water enriched in light isotopes, climatic warming, and increase of biological activity. The Late Glacial deposits are characterized by δ18O values of ca −6.5-6‰ and δ13C of ca −1‰. In the transitional time between the Late Glacial and the Holocene, δ18O systematically falls below −8‰, reflecting a substantial change in the isotopic composition of the lake water, likely caused by to inflow of melt water. During the Preboreal period the δ18O as well as the δ13C values systematically decrease and reach minima (−8.4-9.4‰ for δ18O and ca −3.5-4.7‰ for δ13C. At the beginning of the Boreal period, an increase of ca 2‰ in δ18O is noted and is associated with climatic warming. During the Atlantic period the varying trends in the δ18O record are likely connected with changing precipitation/evaporation ratios, causing changes in the isotope composition of the water. The fluctuations of the

  9. Kinetics in the critical zone : insights from Mg & Sr isotopes in landslides

    Science.gov (United States)

    Galy, Albert; Emberson, Robert; Bedja, Imene; Hovius, Niels

    2017-04-01

    The critical zone is characterized by a wide range of characteristic time, from s to Myr. When the water/rock interaction is considered, the kinetic of the chemical reaction can be slow enough to become the driver of the geochemical imprint of the water (rather than the hydrological residence time). This led the idea that the changes in isotopic ratios in terrestrial surface waters should correspond to changes in the overall dissolution. When chemical elements or isotopic signatures are characteristic to one lithology, namely silicate, this implies that the silicate mineral phases that act as sources of a given isotope dissolve at a rate that is proportional to the overall silicate weathering. However, bedrock landsliding exhumes large quantities of fresh rock that get weathered in transient storage (the bottom of the landslide's scar), and rapid weathering in these deposits is controlled primarily by dissolution of the most reactive phases. In this study, we test the hypothesis that preferential weathering of labile minerals can decouple the dissolution of strontium and magnesium sources from the actual silicate weathering rates in the rapidly eroding Western Southern Alps (WSA) of New Zealand. We find that rapid dissolution of calcite enriched in radiogenic strontium during regional metamorphism and biotite (minerals always characterised by elevated 87Sr/86Sr) in landslides leads to high local fluxes in strontium with isotopic ratios that offer no clear discrimination between sources. These higher fluxes of radiogenic strontium are in contrast to silicate weathering rates in landslides that are not systematically elevated. On the contrary, the magnesium isotopes are barely affected by the preferential weathering of these 2 labile minerals. This could be related that biotite hosts the majority of the magnesium in the Alpine Schist and its dissolution buffer the isotopic signature. However the values are different from the signature of pure biotite. Magnesium

  10. Spectroscopy of transfermium isotopes at SHIP

    Energy Technology Data Exchange (ETDEWEB)

    Antalic, Stanislav; Saro, Stefan; Venhart, Martin [Comenius University, Bratislava (Slovakia); Hessberger, Fritz Peter; Ackermann, Dieter; Heinz, Sophia; Kindler, Birgit; Kojouharov, Ivan; Lommel, Bettina; Mann, Rido; Streicher, Branislav [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Hofmann, Sigurd [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Goethe-Universitaet, Frankfurt am Main (Germany); Sulignano, Barbara [CEA-Saclay, DAPNIA/SPhN, Gif-sur-Yvette (France)

    2009-07-01

    Recent developments of experimental techniques suited for {alpha}-, {gamma}- and CE spectroscopy now allow to study nuclear structure in the region of trans-fermium nuclei. This opened the door to investigate nuclear structure under extreme conditions of heaviest nuclei (Z>100,A>250). Most interesting examples are studies of K-isomers. Experiments aimed to investigate such phenomena provide important information on the nuclear structure of the heaviest elements and are stringent tests for the quality of nuclear models. In this contribution the results from studies of multi-quasi-particle isomeric states in {sup 253}No and {sup 255}Lr performed at SHIP are presented in detail. Both nuclei are first odd-mass isotopes in the trans-fermium region for which high K-isomers were observed. By decay of the high K-isomer in {sup 253}No a rotational band was populated, which was not seen in previous in-beam studies. Additionally, also the recent results on the single particle level systematics for the N=149, 151 and 153 isotones are presented.

  11. Crystal chemical constraints on inter-mineral Fe isotope fractionation and implications for Fe isotope disequilibrium in San Carlos mantle xenoliths

    Science.gov (United States)

    Macris, Catherine A.; Manning, Craig E.; Young, Edward D.

    2015-04-01

    The origin of variations in iron isotope compositions of mantle minerals is uncertain, and predictions of equilibrium inter-mineral iron isotope fractionation conflict. This hinders interpretation of the petrologic and geochemical implications of Fe isotope data from mantle lithologies. To address this, we present a revised ionic model for predicting equilibrium iron isotope fractionation between mantle minerals and use it to interpret measured inter-mineral iron isotopic fractionation from five distinct mantle xenolith lithologies from San Carlos, Arizona. The samples represent a broad range of modal abundances and include lherzolite, harzburgite, dunite, clinopyroxenite, and websterite. The xenoliths exhibit Fe-isotopic variation between minerals in a single sample, and between samples. In all cases where spinel and olivine coexist, the 57Fe/54Fe of spinel is greater than that of the corresponding olivine, agreeing with expectations for equilibrium fractionation from theory (ionic model), but disagreeing with predictions based on Mössbauer data. The 57Fe/54Fe values of clinopyroxenes from the xenoliths show no clear systematic differences. We interpret this to be a result of varying degrees of metasomatism, perhaps involving interaction with a melt. The spinel peridotite samples (lherzolite, harzburgite, and dunite) are partially melted residual mantle that exhibit a decrease in whole-rock 57Fe/54Fe with increasing olivine abundance. This is consistent with progressive extraction of a 57Fe-rich partial melt. The clinopyroxenite has the highest whole-rock 57Fe/54Fe, consistent with its origin as a cumulate from an unrelated magma possessing elevated 57Fe/54Fe. The websterite sample is transitional to Group II type xenoliths, has the lowest whole-rock 57Fe/54Fe of the investigated samples, and likely experienced a more complex metasomatic history. This study demonstrates that the Fe isotope compositions of San Carlos xenoliths and their component minerals record

  12. Microscopic study of neutron-rich dysprosium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Carlos E. [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico); Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Velazquez, Victor [Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Lerma, Sergio [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico)

    2013-01-15

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, {gamma} and {beta} bands, and their B(E2) transition strengths in {sup 160-168}Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of {gamma} and {beta} bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus {sup 170}Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  13. Stable iron isotopes and microbial mediation in red pigmentation of the Rosso Ammonitico (mid-late Jurassic, Verona area, Italy).

    Science.gov (United States)

    Préat, Alain R; de Jong, Jeroen T M; Mamet, Bernard L; Mattielli, Nadine

    2008-08-01

    The iron (Fe) isotopic composition of 17 Jurassic limestones from the Rosso Ammonitico of Verona (Italy) have been analyzed by Multiple-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Such analysis allowed for the recognition of a clear iron isotopic fractionation (mean -0.8 per thousand, ranging between -1.52 to -0.06 per thousand) on a millimeter-centimeter scale between the red and grey facies of the studied formation. After gentle acid leaching, measurements of the Fe isotopic compositions gave delta(56)Fe values that were systematically lower in the red facies residues (median: -0.84 per thousand, range: -1.46 to +0.26 per thousand) compared to the grey facies residues (median: -0.08 per thousand, range: -0.34 to +0.23 per thousand). In addition, the red facies residues were characterized by a lighter delta(56)Fe signal relative to their corresponding leachates. These Fe isotopic fractionations could be a sensitive fingerprint of a biotic process; systematic isotopic differences between the red and grey facies residues, which consist of hematite and X-ray amorphous iron hydroxides, respectively, are hypothesized to have resulted from the oxidizing activity of iron bacteria and fungi in the red facies. The grey Fe isotopic data match the Fe isotopic signature of the terrestrial baseline established for igneous rocks and low-C(org) clastic sedimentary rocks. The Fe isotopic compositions of the grey laminations are consistent with the influx of detrital iron minerals and lack of microbial redox processes at the water-interface during deposition. Total Fe concentration measurements were performed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) (confirmed by concentration estimations obtained by MC-ICP-MS analyses of microdrilled samples) on five samples, and resultant values range between 0.30% (mean) in the grey facies and 1.31% (mean) in the red facies. No correlation was observed between bulk Fe content and pigmentation

  14. Using multiple isotopes to understand the source of ingredients used in golden beverages

    Science.gov (United States)

    Wynn, J. G.

    2011-12-01

    Traditionally, beer contains 4 simple ingredients: water, barley, hops and yeast. Each of these ingredients used in the brewing process contributes some combination of a number of "traditional" stable isotopes (i.e., isotopes of H, C, O, N and S) to the final product. As an educational exercise in an "Analytical Techniques in Geology" course, a group of students analyzed the isotopic composition of the gas, liquid and solid phases of a variety of beer samples collected from throughout the world (including other beverages). The hydrogen and oxygen isotopic composition of the water followed closely the isotopic composition of local meteoric water at the source of the brewery, although there is a systematic offset from the global meteoric water line that may be due to the effects of CO2-H2O equilibration. The carbon isotopic composition of the CO2 reflected that of the solid residue (the source of carbon used as a fermentation substrate), but may potentially be modified by addition of gas-phase CO2 from an inorganic source. The carbon isotopic composition of the solid residue similarly tracks that of the fermentation substrate, and may indicate some alcohol fermented from added sugars in some cases. The nitrogen isotopic composition of the solid residue was relatively constant, and may track the source of nitrogen in the barley, hops and yeast. Each of the analytical methods used is a relatively standard technique used in geological applications, making this a "fun" exercise for those involved, and gives the students hands-on experience with a variety of analytes from a non-traditional sample material.

  15. Zinc isotopic compositions of breast cancer tissue.

    Science.gov (United States)

    Larner, Fiona; Woodley, Laura N; Shousha, Sami; Moyes, Ashley; Humphreys-Williams, Emma; Strekopytov, Stanislav; Halliday, Alex N; Rehkämper, Mark; Coombes, R Charles

    2015-01-01

    An early diagnostic biomarker for breast cancer is essential to improve outcome. High precision isotopic analysis, originating in Earth sciences, can detect very small shifts in metal pathways. For the first time, the natural intrinsic Zn isotopic compositions of various tissues in breast cancer patients and controls were determined. Breast cancer tumours were found to have a significantly lighter Zn isotopic composition than the blood, serum and healthy breast tissue in both groups. The Zn isotopic lightness in tumours suggests that sulphur rich metallothionein dominates the isotopic selectivity of a breast tissue cell, rather than Zn-specific proteins. This reveals a possible mechanism of Zn delivery to Zn-sequestering vesicles by metallothionein, and is supported by a similar signature observed in the copper isotopic compositions of one breast cancer patient. This change in intrinsic isotopic compositions due to cancer has the potential to provide a novel early biomarker for breast cancer.

  16. Measuring SNM Isotopic Distributions using FRAM

    Energy Technology Data Exchange (ETDEWEB)

    Geist, William H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-02

    The first group of slides provides background information on the isotopic composition of plutonium. It is shown that 240Pu is the critical isotope in neutron coincidence/multiplicity counting. Next, response function analysis to determine isotopic composition is discussed. The isotopic composition can be determined by measuring the net peak counts from each isotope and then taking the ratio of the counts for each isotope relative to the total counts for the element. Then FRAM (Fixed energy Response function Analysis with Multiple efficiencies) is explained. FRAM can control data acquisition, automatically analyze newly acquired data, analyze previously acquired data, provide information on the quality of the analysis, and facilitate analysis in unusual situations (non-standard energy calibrations, gamma rays from non-SNM isotopes, poor spectra (within limits)).

  17. Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems

    Energy Technology Data Exchange (ETDEWEB)

    Nimz, G. J., LLNL

    1998-06-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water. Many solutes in natural waters are derived from the interaction between the water and the rock and/or soil within the system - these are termed `lithogenic` solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both within and outside of the catchment - i.e., in addition to being derived from catchment rock and soil, they are solutes that are also transported into the catchment. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing `cosmogenic` nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing `thermonuclear` nuclides), or radioactive and fission decay of naturally-occurring elements, principally {sup 238}U (producing `in-situ` lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading `cosmogenic nuclides`, and for simplicity we will often follow that usage here, although always indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute concentrations in catchment waters, and how the isotopic compositions of the solutes can be used in integrative ways to identify these processes, thereby revealing the physical history of the water within a catchment system. The concept of a `system` is important in catchment hydrology. A catchment is the smallest landscape unit that can both participate in all of the aspects of the hydrologic cycle and

  18. Quantification of Calcium Isotope Fractionation in Ectomycorrhizal Trees

    Science.gov (United States)

    Hoff, C. J.; Bryce, J. G.; Hobbie, E. A.; Colpaert, J. V.; Bullen, T. D.

    2005-12-01

    Calcium plays a significant role in many forest ecosystem processes and is required for plant growth. Within plants, calcium is a critical component of cell walls and membranes, signaling processes, and charge balances (1). Current efforts to quantify Ca cycling in ecosystems rely on large-scale ecosystem manipulations (e.g., 2) or mass balances (e.g., 3) and indirect chemical proxies, Ca/Sr or Sr isotopic systems (e.g., 4). The measurement of Ca isotopes may provide more direct information about the calcium sources and fluxes within and between the geological (mineral and soil) and biological (fungi and plants) components of terrestrial ecosystems. To examine calcium isotopic variability systematically, we measured the fractionation between roots and needles in cultured Scots pine ( Pinus sylvestris) seedlings. Our samples include roots and needles from trees grown at low or high nutrient supply rates (3% or 5% per day). Because mycorrhizal fungi are intimately involved in plant nutrient supply, we also tested whether mycorrhizal colonization by Suillus bovinus affected calcium isotopic fractionation. Initial results demonstrate that at a low nutrient supply rate there is a small but measurable fractionation (averaging 0.58 ‰) between the roots and needles of individual trees; the needles are enriched in 40Ca compared to the roots. The root-needle fractionation is unaffected by mycorrhizal colonization. Ongoing analyses will address both the consistency of the root-needle fractionation and the impacts of nutrient supply rate on fractionation. Preliminary results suggest that higher nutrient supply rates lead to decreased root-needle fractionation. Analyses underway will also address whether different fungal species ( Thelephora terrestris) affect the documented root-needle fractionation. Isotope signatures of calcium source materials will complete our sample suite and will be used to assess fractionation during uptake. Ultimately, the results of this study will

  19. Unexpected hydrogen isotope variation in oceanic pelagic seabirds

    Science.gov (United States)

    Ostrom, Peggy H.; Wiley, Anne E.; Rossman, Sam; Stricker, Craig A.; James, Helen F.

    2014-01-01

    Hydrogen isotopes have significantly enhanced our understanding of the biogeography of migratory animals. The basis for this methodology lies in predictable, continental patterns of precipitation δD values that are often reflected in an organism's tissues. δD variation is not expected for oceanic pelagic organisms whose dietary hydrogen (water and organic hydrogen in prey) is transferred up the food web from an isotopically homogeneous water source. We report a 142% range in the δD values of flight feathers from the Hawaiian petrel (Pterodroma sandwichensis), an oceanic pelagic North Pacific species, and inquire about the source of that variation. We show δD variation between and within four other oceanic pelagic species: Newell's shearwater (Puffinus auricularis newellii), Black-footed albatross (Phoebastria nigripes), Laysan albatross (Phoebastria immutabilis) and Buller's shearwater (Puffinus bulleri). The similarity between muscle δD values of hatch-year Hawaiian petrels and their prey suggests that trophic fractionation does not influence δD values of muscle. We hypothesize that isotopic discrimination is associated with water loss during salt excretion through salt glands. Salt load differs between seabirds that consume isosmotic squid and crustaceans and those that feed on hyposmotic teleost fish. In support of the salt gland hypothesis, we show an inverse relationship between δD and percent teleost fish in diet for three seabird species. Our results demonstrate the utility of δD in the study of oceanic consumers, while also contributing to a better understanding of δD systematics, the basis for one of the most commonly utilized isotope tools in avian ecology.

  20. Isotopic evidence of pollutant lead sources in Northwestern France

    Science.gov (United States)

    Véron, Alain; Flament, Pascal; Bertho, Marie Laure; Alleman, Laurent; Flegal, Russell; Hamelin, Bruno

    Ratios of stable lead isotopes ( 204Pb, 206Pb, 207Pb, 208Pb) are used to characterize both spatial and temporal variations in anthropogenic emissions of industrial lead aerosols to the atmosphere of northwestern France. Differences in isotopic compositions of aerosols collected from a rural area (Wimereux) in the Nord-Pas de Calais region along the English Channel in 1982-1983 ( 206Pb/ 207Pb=1.108±0.005) and 1994 ( 206Pb/ 207Pb=1.148±0.003) are paralleled by similar variations in urban aerosols within France during the same period (e.g., 206Pb/ 207Pb=1.115±0.008 from 1981-1989 and 1.143±0.006 from 1992-1995). These results correlate well with recent findings in the Mediterranean basin (Alleman, 1997) where this radiogenicity increase is clearly associated with industrial sources other than leaded gasoline that has remained relatively constant during its phasing out ( 206Pb/ 207Pb=1.08-1.11). Here we used archived data, air mass trajectories and aerosol diameters combined with isotopic signatures to confirm this trend at a regional scale. Indeed, the main industrial signatures from lead smelting ( 206Pb/ 207Pb=1.133±0.001) and steel metallurgy ( 206Pb/ 207Pb=1.196±0.015) in northwestern France appear more radiogenic than that of leaded gasoline. The shift in isotopic compositions also conform with the systematic change in the mean size (diameter) of aerosols at Wimereux, which ranged from 0.30 to 0.61 μm in 1982-1984 and from 0.70 to 0.89 μm in 1994.

  1. Methane clumped isotopes: Progress and potential for a new isotopic tracer

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, Peter M. J.; Stolper, Daniel A.; Eiler, John M.; Sessions, Alex L.; Lawson, Michael; Shuai, Yanhua; Bishop, Andrew; Podlaha, Olaf G.; Ferreira, Alexandre A.; Santos Neto, Eugenio V.; Niemann, Martin; Steen, Arne S.; Huang, Ling; Chimiak, Laura; Valentine, David L.; Fiebig, Jens; Luhmann, Andrew J.; Seyfried, William E.; Etiope, Giuseppe; Schoell, Martin; Inskeep, William P.; Moran, James J.; Kitchen, Nami

    2017-11-01

    The isotopic composition of methane is of longstanding geochemical interest, with important implications for understanding hydrocarbon systems, atmospheric greenhouse gas concentrations, the global carbon cycle, and life in extreme environments. Recent analytical developments focusing on multiply substituted isotopologues (‘clumped isotopes’) are opening a potentially valuable new window into methane geochemistry. When methane forms in internal isotopic equilibrium, clumped isotopes can provide a direct record of formation temperature, making this property particularly valuable for identifying different methane origins. However, it has also become clear that in certain settings methane clumped isotope measurements record kinetic rather than equilibrium isotope effects. Here we present a substantially expanded dataset of methane clumped isotope analyses, and provide a synthesis of the current interpretive framework for this parameter. We review different processes affecting methane clumped isotope compositions, describe the relationships between conventional isotope and clumped isotope data, and summarize the types of information that this measurement can provide in different Earth and planetary environments.

  2. Core correlation effects in multiconfiguration calculations of isotope shifts in Mg I

    CERN Document Server

    Filippin, Livio; Ekman, Jörgen; Jönsson, Per

    2016-01-01

    The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of isotope shifts for several well-known transitions in neutral magnesium. Relativistic normal and specific mass shift factors as well as the electronic probability density at the origin are calculated. Combining these electronic quantities with available nuclear data, energy and transition level shifts are determined for the $^{26}$Mg$-^{24}$Mg pair of isotopes. Different models for electron correlation are adopted. It is shown that although valence and core-valence models provide accurate values for the isotope shifts, the inclusion of core-core excitations in the computational strategy significantly improves the accuracy of the transition energies and normal mass shift factors.

  3. Nuclear radii of thorium isotopes from laser spectroscopy of stored ions

    Energy Technology Data Exchange (ETDEWEB)

    Kaelber, W.; Rink, J.; Bekk, K.; Goering, S.; Meisel, G.; Rebel, H.; Faubel, W.; Thompson, R.C.

    1989-09-01

    Isotope shifts and hyperfine splittings in optical transitions for atomic ions of the thorium isotopes /sup 227/Th to /sup 230/Th and /sup 232/Th have been measured by laser spectroscopy on stored ions. From the isotope shift data, changes of the mean square charge radii are determined. A continuous increase of the charge radius with mass number A is observed, in agreement with droplet model calculations. The results indicate that the odd-even staggering for Th is different from that one of the neighbouring isotones of Fr and Ra. There is some empirical evidence from systematics for an inversion of the staggering and the appearance of an octupole deformation at N/le/137. The hyperfine splitting for /sup 229/Th for 3 electronic levels is given. (orig.).

  4. Anthropogenic lead isotopes in Antarctica

    Science.gov (United States)

    Rosman, K. J. R.; Chisholm, W.; Boutron, C. F.; Candelone, J.-P.; Patterson, C. C.

    1994-12-01

    We report the first measurements of Pb isotopes in Antarctic snow, which show that even recent snow containing 2.3 pg/g is highly polluted with anthropogenic Pb. This follows from a comparison of isotope abundances of Pb in surface snow and terrestrial dust extracted from ancient Antarctic ice (Dome C, depth 308 m, approximate age 7,500 a BP), the latter being distinctly more radiogenic. This result is dependent of geochemical arguments based on measurements of Al, Na and SO4. South America is suggested as a likely source of this anthropogenic Pb. The presence of significantly less radiogenic Pb in the snow adjacent to two Antarctic base stations indicates that there is contamination from station emissions, although emission from Australia is an alternative explanation for a site 33 km from Dumont d'Urville.

  5. Lead isotope studies of the Guerrero composite terrane, west-central Mexico: implications for ore genesis

    Science.gov (United States)

    Potra, Adriana; Macfarlane, Andrew W.

    2014-01-01

    New thermal ionization mass spectrometry and multi-collector inductively coupled plasma mass spectrometry Pb isotope analyses of three Cenozoic ores from the La Verde porphyry copper deposit located in the Zihuatanejo-Huetamo subterrane of the Guerrero composite terrane are presented and the metal sources are evaluated. Lead isotope ratios of 3 Cenozoic ores from the El Malacate and La Esmeralda porphyry copper deposits located in the Zihuatanejo-Huetamo subterrane and of 14 ores from the Zimapan and La Negra skarn deposits from the adjoining Sierra Madre terrane are also presented to look for systematic differences in the lead isotope trends and ore metal sources among the proposed exotic tectonostratigraphic terranes of southern Mexico. Comparison among the isotopic signatures of ores from the Sierra Madre terrane and distinct subterranes of the Guerrero terrane supports the idea that there is no direct correlation between the distinct suspect terranes of Mexico and the isotopic signatures of the associated Cenozoic ores. Rather, these Pb isotope patterns are interpreted to reflect increasing crustal contribution to mantle-derived magmas as the arc advanced eastward onto a progressively thicker continental crust. The lead isotope trend observed in Cenozoic ores is not recognized in the ores from Mesozoic volcanogenic massive sulfide and sedimentary exhalative deposits. The Mesozoic ores formed prior to the amalgamation of the Guerrero composite terrane to the continental margin, which took place during the Late Cretaceous, in intraoceanic island arc and intracontinental marginal basin settings, while the Tertiary deposits formed after this event in a continental arc setting. Lead isotope ratios of the Mesozoic and Cenozoic ores appear to reflect these differences in tectonic setting of ore formation. Most Pb isotope values of ores from the La Verde deposit (206Pb/204Pb = 18.674-18.719) are less radiogenic than those of the host igneous rocks, but plot within the

  6. One year observation of water vapour isotopic composition at Ivittuut, Southern Greenland

    Science.gov (United States)

    Bonne, Jean-Louis; Masson-Delmotte, Valérie; Delmotte, Marc; Cattani, Olivier; Sodemann, Harald; Risi, Camille

    2013-04-01

    ). Simulations of humidity transport based on an adapted version of the Lagrangian dispersion model Flexpart allows to diagnose Ivittuut moisture sources, to retrieve the evaporation conditions, and to distinguish the influence of local and remote processes on our measurements. This site is strongly influenced by large scale humidity transport from distant sources such as seas surrounding Greenland and western to eastern North Atlantic ocean. The consistency of Flexpart calculations with isotopic distillation will be investigated. Our observations are finally compared to daily outputs of a nudged simulation conducted with the LMDZiso AGCM nudged to atmospheric analyses. This comparison will be performed at synoptic to seasonal scales allowing to assess the spatial representativeness of our station and to identify systematic model biases. The added value of water vapour isotopic data to constrain moisture sources and assess the realism of their simulation will be discussed.

  7. Isotope fractionation of cadmium in lunar material

    Science.gov (United States)

    Schediwy, S.; Rosman, K. J. R.; de Laeter, J. R.

    2006-03-01

    The double spike technique has been used to measure the isotope fractionation and elemental abundance of Cd in nine lunar samples, the Brownfield meteorite and the Columbia River Basalt BCR-1, by thermal ionisation mass spectrometry. Lunar soil samples give a tightly grouped set of positive isotope fractionation values of between + 0.42% and + 0.50% per mass unit. Positive isotope fractionation implies that the heavy isotopes are enhanced with respect to those of the Laboratory Standard. A vesicular mare basalt gave zero isotope fractionation, indicating that the Cd isotopic composition of the Moon is identical to that of the Earth. A sample of orange glass from the Taurus-Littrow region gave a negative isotope fractionation of - 0.23 ± 0.06% per mass unit, presumably as a result of redeposition of Cd from the Cd-rich vapour cloud associated with volcanism. Cadmium is by far the heaviest element to show isotope fractionation effects in lunar samples. The volatile nature of Cd is of importance in explaining these isotope fractionation results. Although a number of mechanisms have been postulated to be the cause of isotope fractionation of certain elements in lunar soils, we believe that the most likely mechanisms are ion and particle bombardment of the lunar surface.

  8. Anthropogenic lead isotopes in Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, K.J.R.; Chisholm, W. [Curtin Univ. of Technology, Bentley (Australia); Boutron, C.F. [Laboratoire de Glaciologie et Geophysique de l`Environnement du CNRS, St. Martin d`Heres (France)]|[Domaine Universitaire, Grenoble (France); Candelone, J.P. [Laboratoire de Glaciologie et Geophysique de l`Environnement du CNRS, St. Martin d`Heres (France); Patterson, C.C. [California Institute of Technology, Pasadena, CA (United States)

    1994-12-01

    The authors present results from the first Pb isotopic study of the sources of lead in snow samples from the Antarctic. Samples of recent snow fields were compared with measurements of samples taken from deep cores, and they reveal that recent snows show pronounced influence of anthropogenic sources. These results are independent of geochemical arguments based on influences of Al, Na, or SO{sub 4}.

  9. Comparative isotope ecology of African great apes.

    Science.gov (United States)

    Oelze, Vicky M; Fahy, Geraldine; Hohmann, Gottfried; Robbins, Martha M; Leinert, Vera; Lee, Kevin; Eshuis, Henk; Seiler, Nicole; Wessling, Erin G; Head, Josephine; Boesch, Christophe; Kühl, Hjalmar S

    2016-12-01

    The isotope ecology of great apes is a useful reference for palaeodietary reconstructions in fossil hominins. As extant apes live in C3-dominated habitats, variation in isotope signatures is assumed to be low compared to hominoids exploiting C4-plant resources. However, isotopic differences between sites and between and within individuals are poorly understood due to the lack of vegetation baseline data. In this comparative study, we included all species of free-ranging African great apes (Pan troglodytes, Pan paniscus, Gorilla sp.). First, we explore differences in isotope baselines across different habitats and whether isotopic signatures in apes can be related to feeding niches (faunivory and folivory). Secondly, we illustrate how stable isotopic variations within African ape populations compare to other extant and extinct primates and discuss possible implications for dietary flexibility. Using 701 carbon and nitrogen isotope data points resulting from 148 sectioned hair samples and an additional collection of 189 fruit samples, we compare six different great ape sites. We investigate the relationship between vegetation baselines and climatic variables, and subsequently correct great ape isotope data to a standardized plant baseline from the respective sites. We obtained temporal isotopic profiles of individual animals by sectioning hair along its growth trajectory. Isotopic signatures of great apes differed between sites, mainly as vegetation isotope baselines were correlated with site-specific climatic conditions. We show that controlling for plant isotopic characteristics at a given site is essential for faunal data interpretation. While accounting for plant baseline effects, we found distinct isotopic profiles for each great ape population. Based on evidence from habituated groups and sympatric great ape species, these differences could possibly be related to faunivory and folivory. Dietary flexibility in apes varied, but temporal variation was overall

  10. WWW Table of Radioactive Isotopes

    Science.gov (United States)

    Firestone, R. B.; Ekstrom, L. P.; Chu, S. Y. F.

    1999-10-01

    An electronic sequel to the Table of Radioactive Isotopes (John Wiley, 1986) is being developed for use on the WWW. Updated adopted and decay data from the Evaluated Nuclear Structure Decay File (ENSDF) and other sources have been combined and edited. Decay scheme normalizations are revised when necessary. Gamma-ray and alpha-particle energies can be searched interactively by energy or parent half-life, mass, and atomic or neutron number. Summary data including half-lives, Q-values, production mode(s), genetic feedings, and a list of references published since the last full evaluation are available. Users can display energy or intensity ordered tables of gamma-rays, K and L x-rays, alpha-particles, and beta endpoints. Spectra of betas and bremsstrahlung, and Auger/conversion electrons can be viewed with an interactive JAVA applet. Decay schemes can be displayed with the JAVA version of Isotope Explorer 3.0. The URL for the Table of Radioactive Isotopes is http://nucleardata.nuclear.lu.se/nucleardata/toi/.

  11. The Yellowstone hotspot in space and time: Nd and Hf isotopes in silicic magmas

    Science.gov (United States)

    Nash, Barbara P.; Perkins, Michael E.; Christensen, John N.; Lee, Der-Chuen; Halliday, A. N.

    2006-07-01

    Over the course of its 16 m.y. history, the Yellowstone hotspot has produced silicic magmas exhibiting systematic, and often sympathetic, variations in isotopic and chemical composition, temperature and frequency of eruption. Nd and Hf isotopic ratios vary systematically from initial eruptions at ˜ 16 Ma, contemporaneous with basaltic volcanism in eastern Oregon and Washington, to the present day Yellowstone Volcanic Plateau. Nd and Hf isotopic ratios co-vary and span the range of most terrestrial samples, reflecting mixing of mantle and crustal sources. Earliest erupted silicic magmas were hot (in excess of 1050 °C), relatively less evolved and have isotopic ratios within the range of contemporaneous Columbia River flood basalts. The transit of the hotspot across the lithospheric boundary between the western accreted oceanic terrain and the Precambrian craton at 15 Ma is marked by shifts in ɛNd from + 4 to - 11 and in ɛHf from + 10 to - 10. The duration of the transit yields a crustal magma source diameter of ˜ 70 km. In the interval from 14 to 9 Ma, ɛNd systematically increases from - 11 to - 7, recording a minimum increase in the mantle component from 5% to 30%. The mantle component could be twice as great, depending upon the isotopic composition of crust and mantle reservoirs. In this same interval, peak temperatures of ˜ 1000 °C occurred at 9 Ma. The last 8 m.y. are characterized by less frequent eruption of lower temperature (830-900 °C) and more compositionally evolved magmas.

  12. The Yellowstone hotspot in space and time: Nd and Hf isotopes insilici magmas

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Barbara P.; Perkins, Michael E.; Christensen, John N.; Lee,Den-Chuen; Halliday, A.N.

    2006-04-19

    Over the course of its 16 m.y. history, the Yellowstonehotspot has produced silicic magmas exhibiting systematic, and oftensympathetic, variations in isotopic and chemical composition, temperatureand frequency of eruption. Nd and Hf isotopic ratios vary systematicallyfrom initial eruptions at ~;16 Ma, contemporaneous with basalticvolcanism in eastern Oregon and Washington, to the present dayYellowstone Volcanic Plateau. Nd and Hf isotopic ratios co-vary and spanthe range of most terrestrial samples, reflecting mixing of mantle andcrustal sources. Earliest erupted silicic magmas were hot (in excess of1050oC), relatively less evolved and have isotopic ratios within therange of contemporaneous Columbia River flood basalts. The transit of thehotspot across the lithospheric boundary between the western accretedoceanic terrain and the Precambrian craton at 15 Ma is marked by shiftsin eNd from +4 to -11 and in ?Hf from +10 to -10. The duration of thetransit yields a crustal magma source diameter of ~;70 km. In theinterval from 14 to 9 Ma, ?Nd systematically increases from -11 to -7,recording a minimum increase in the mantle component from 5 percent to 30percent. The mantle component could be twice as great, depending upon theisotopic composition of crust and mantle reservoirs. In this sameinterval, peak temperatures of ~;1000oC occurred at 9 Ma. The last 8 m.y.are characterized by less frequent eruption of lower temperature(830-900oC) and more compositionally evolved magmas.

  13. Evaluating Young Volcanism at Baitoushan Volcano: Insights From Single Mineral Crystal Sr and Pb Isotope Analyses

    Science.gov (United States)

    Rodgers, S. L.; Ramos, F. C.; Gill, J. B.

    2008-12-01

    Baitoushan volcano, located along the North-Korea/China border, generated one of the largest caldera- forming rhyolitic eruptions in the northern hemisphere in the last 2000 years. In addition to a large ~1000AD comendite eruption, a pantellerite eruption occurred at ~0AD which left a small pumice deposit. We have evaluated the isotopic signatures of single mineral crystals and pumice fragments from this pantellerite to evaluate the sources, petrogenetic history, timing, and residence of highly alkaline rhyolitic magma at Baitoushan. Single mineral isotope characteristics of this pantellerite are complex. Rb/Sr analyses of whole pumice fragments suggest a pantellerite residence age of ~348ky, similar to residence ages determined for Long Valley Caldera and Valles Caldera. Individual potassium feldspar and clinopyroxene crystals have similarly variable and overlapping 87Sr/86Sr signatures that are different than those of host pumice fragments but similar to crystals erupted in the ~1000AD comendite. These same crystals define a linear trend in 207Pb/204Pb vs 206Pb/204Pb that suggests mixing between host pumice and a second currently unidentified endmember. Results, however, unequivocally demonstrate mixing and undermine any residence age associated with Rb/Sr isotope systematics of pumice fragments. Overall Sr and Pb isotope systematics reflect variable signatures as compared to all other recent eruptive products at Baitoushan and suggest highly variable processes involved in melt production and that select minerals may be shared between different eruptions spanning a 2000 to 4000 year time period.

  14. Li-Zn-Pb multi isotopic characterization of the Loire River Basin, France

    Science.gov (United States)

    Millot, R.; Desaulty, A.; Widory, D.; Bourrain, X.

    2013-12-01

    The Loire River in France is approximately 1010 km long and drains an area of 117 800 km2. Upstream, the Loire River flows following a south to north direction from the Massif Central down to the city of Orléans, 650 km from its source. The Loire River is one of the main European riverine inputs to the Atlantic Ocean. Over time, its basin has been exposed to numerous sources of anthropogenic metal pollutions, such as metal mining, industry, agriculture and domestic inputs. The Loire River basin is thus an excellent study site to develop new isotope systematics for tracking anthropogenic sources of metal pollutions (Zn and Pb) and also to investigate Li isotope tracing that can provide key information on the nature of weathering processes at the Loire River Basin scale. Preliminary data show that Li-Zn-Pb concentrations and isotopic compositions span a wide range in river waters of the Loire River main stream and the main tributaries. There is a clear contrast between the headwaters upstream and rivers located downstream in the lowlands. In addition, one of the major tributaries within the Massif Central (the Allier River) is clearly influenced by inputs resulting from mineralizations and thermomineral waters. The results showed that, on their own, each of these isotope systematics reveals important information about the geogenic or anthropogenic origin Li-Zn-Pb. Considered together, they are however providing a more integrated understanding of the overall budgets of these elements at the scale of the Loire River Basin.

  15. Redox reactions and the influence of natural Mn oxides on Cr oxidation in a contaminated site in northern Italy: evidence from Cr stable-isotopes and EPR spectroscopy

    OpenAIRE

    Marafatto F. F.; Petrini R.; Pinzino C.; Pezzetta E.; Slejko F.; Lutman A.

    2013-01-01

    Hexavalent chromium-contaminated groundwaters and sediments in northern Italy have been studied using the Cr stable-isotope systematics and electron spin resonance spectroscopy (ESR), in order to explore redox changes and soil-groundwater interactions. The isotopic data indicate a possible Cr(VI) source released into the environment from an industrial plant. EPR spectra on the sediments which constitute the aquifers show a broad asymmetric absorption due to coupled Fe(III) and coupled Cr(III)...

  16. Isotope Geochemistry for Comparative Planetology of Exoplanets

    Science.gov (United States)

    Mandt, K. E.; Atreya, S.; Luspay-Kuti, A.; Mousis, O.; Simon, A.; Hofstadter, M. D.

    2017-01-01

    Isotope geochemistry has played a critical role in understanding processes at work in and the history of solar system bodies. Application of these techniques to exoplanets would be revolutionary and would allow comparative planetology with the formation and evolution of exoplanet systems. The roadmap for comparative planetology of the origins and workings of exoplanets involves isotopic geochemistry efforts in three areas: (1) technology development to expand observations of the isotopic composition of solar system bodies and expand observations to isotopic composition of exoplanet atmospheres; (2) theoretical modeling of how isotopes fractionate and the role they play in evolution of exoplanetary systems, atmospheres, surfaces and interiors; and (3) laboratory studies to constrain isotopic fractionation due to processes at work throughout the solar system.

  17. Deformation properties of lead isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Tolokonnikov, S. V.; Borzov, I. N.; Lutostansky, Yu. S.; Saperstein, E. E., E-mail: saper43-7@mail.ru [National Research Center Kurchatov Institute (Russian Federation)

    2016-01-15

    The deformation properties of a long lead isotopic chain up to the neutron drip line are analyzed on the basis of the energy density functional (EDF) in the FaNDF{sup 0} Fayans form. The question of whether the ground state of neutron-deficient lead isotopes can have a stable deformation is studied in detail. The prediction of this deformation is contained in the results obtained on the basis of the HFB-17 and HFB-27 Skyrme EDF versions and reported on Internet. The present analysis reveals that this is at odds with experimental data on charge radii and magnetic moments of odd lead isotopes. The Fayans EDF version predicts a spherical ground state for all light lead isotopes, but some of them (for example, {sup 180}Pb and {sup 184}Pb) prove to be very soft—that is, close to the point of a phase transition to a deformed state. Also, the results obtained in our present study are compared with the predictions of some other Skyrme EDF versions, including SKM*, SLy4, SLy6, and UNE1. By and large, their predictions are closer to the results arising upon the application of the Fayans functional. For example, the SLy4 functional predicts, in just the same way as the FaNDF{sup 0} functional, a spherical shape for all nuclei of this region. The remaining three Skyrme EDF versions lead to a deformation of some light lead isotopes, but their number is substantially smaller than that in the case of the HFB-17 and HFB-27 functionals. Moreover, the respective deformation energy is substantially lower, which gives grounds to hope for the restoration of a spherical shape upon going beyond the mean-field approximation, which we use here. Also, the deformation properties of neutron-rich lead isotopes are studied up to the neutron drip line. Here, the results obtained with the FaNDF{sup 0} functional are compared with the predictions of the HFB-17, HFB-27, SKM*, and SLy4 Skyrme EDF versions. All of the EDF versions considered here predict the existence of a region where neutron

  18. α decay of the very neutron-deficient isotopes 197-199Fr

    Science.gov (United States)

    Kalaninová, Z.; Andreyev, A. N.; Antalic, S.; Heßberger, F. P.; Ackermann, D.; Andel, B.; Drummond, M. C.; Hofmann, S.; Huyse, M.; Kindler, B.; Lane, J. F. W.; Liberati, V.; Lommel, B.; Page, R. D.; Rapisarda, E.; Sandhu, K.; Šáro, Š.; Thornthwaite, A.; Van Duppen, P.

    2013-04-01

    Decay properties of the very neutron-deficient isotopes 197-199Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the 2n-4n evaporation channels of the fusion-evaporation reaction 60Ni+141Pr → 201Fr*. Improved α-decay properties of 199Fr were determined and the possible existence of two α-decaying states in this nucleus is discussed. For the isotope 198Fr a broad α-decay energy distribution was detected in the range of (7470-7930) keV and two α-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope 197Fr was identified based on the observation of one α-decay chain yielding Eα=7728(15) keV and T1/2=0.6-0.3+3.0 ms. The systematics of reduced α-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes.

  19. Magmatic recharge buffers the isotopic compositions against crustal contamination in formation of continental flood basalts

    Science.gov (United States)

    Yu, Xun; Chen, Li-Hui; Zeng, Gang

    2017-07-01

    Isotopic compositions of continental flood basalts are essential to understand their genesis and to constrain the character of their mantle sources. Because of potential crustal contamination, it needs to be evaluated if and to which degree these basalts record original isotopic signals of their mantle sources and/or crustal signatures. This study examines the Sr, Nd, Hf, and Pb isotopic compositions of the late Cenozoic Xinchang-Shengzhou (XS) flood basalts, a small-scale continental flood basalt field in eastern China. The basalts show positive correlations between 87Sr/86Sr and 143Nd/144Nd, and negative correlations between 143Nd/144Nd and 176Hf/177Hf, which deviate from compositional arrays of crustal contamination and instead highlight variations in magmatic recharge intensity and mantle source compositions. The lava samples formed by high-volume magmatic recharge recorded signals of recycled sediments in the mantle source, which are characterized by moderate Ba/Th (91.9-106.5), excess 208Pb/204Pb relative to 206Pb/204Pb, and excess 176Hf/177Hf relative to 143Nd/144Nd. Thus, we propose that magmatic recharge buffers the original isotopic compositions of magmas against crustal contamination. Identifying and utilizing the isotope systematics of continental flood basalts generated by high volumes of magmatic recharge are thus crucial to trace their mantle sources.

  20. Does Oxygen Isotopic Heterogeneity in Refractory Inclusions and Their Wark-Lovering Rims Record Nebular Repressing?

    Science.gov (United States)

    Simon, J. I.; Matzel, J. E. P.; Simon, S. B.; Weber, P. K.; Grossman, L.; Ross, D. K.; Hutcheon, I. D.

    2013-01-01

    Large systematic variations in O-isotopic compositions found within individual mineral layers of rims surrounding Ca-, Al-rich inclusions (CAIs) and at the margins of some CAIs imply formation from distinct environments [e.g., 1-3]. The O-isotope compositions of many CAIs preserve a record of the Solar nebula gas believed to initially be O-16-rich (delta O-17 less than or equal to -25%0) [4-5]. Data from a recent study of the compact Type A Allende CAI, A37, preserve a diffusion profile in the outermost 70 micrometers of the inclusion and show greater than 25%0 variations in delta O-17 within its 100 micrometer-thick Wark-Lovering rim (WL-rim) [3]. This and comparable heterogeneity measured in several other CAIs have been explained by isotopic mixing between the O-16-rich Solar reservoir and a second O-16-poor reservoir (probably nebular gas) with a planetary-like isotopic composition, e.g., [1,2,3,6]. However, there is mineralogical and isotopic evidence from the interiors of CAIs, in particular those from Allende, for parent body alteration. At issue is how to distinguish the record of secondary reprocessing in the nebula from that which occurred on the parent body. We have undertaken the task to study a range of CAI types with varying mineralogies, in part, to address this problem.

  1. Isotopic Studies of Contaminant Transport at the Hanford Site,WA

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, J.N.; Conrad, M.E.; DePaolo, D.J.; Dresel, P.E.

    2006-11-01

    Processes of fluid flow and chemical transport through thevadose zone can be characterized through the isotopic systematics ofnatural soils, minerals, pore fluids and groundwater. In thiscontribution, we first review our research using measured isotopicvariations, due both to natural and site related processes, of theelements H, O, N, Sr and U, to study the interconnection between vadosezone and groundwater contamination at the Hanford Site in south-centralWashington. We follow this brief review with a presentation of new datapertaining to vadose zone and groundwater contamination in the WMAT-TX-TY vicinity. Uranium (U) isotopic data for the C3832 core (WMA TX)indicates the involvement of processed natural U fuel, and links theobserved U contamination to the nearby single shelled tank TX-104. Thedata also precludes contamination from an early 1970 s TX-107 leak. Inthe case of the C4104 core (WMA T), the U isotopic data indicates amixture of processed natural and enriched U fuels consistent with themajor leak from T-106 in 1973. Uranium and Strontium isotopic data forthe cores also provides direct evidence for chemical interaction betweenhigh-pH waste fluid and sediment. Isotopic data for groundwater nitratecontamination in the vicinity of WMA-T strongly suggests high-level tankwaste (most likely from T-106) as the source of very high 99Tcconcentrations recently observed at the NE corner of WMAT.

  2. Tracking mobility using human hair: What can we learn from lead and strontium isotopes?

    Science.gov (United States)

    Vautour, Geneviève; Poirier, André; Widory, David

    2015-01-01

    The isotope ratios of strontium (Sr) and lead (Pb) in water derive from local geology and their isotopic signature can be linked to the age and type of underlying bedrocks and soils (if applicable), and are transferred up the food-chain. Both elements are transferred to human blood through diet and water, and some of it will ultimately be incorporated into the hair structure, making Sr and Pb isotopes interesting tools for tracing human mobility. In this study, we analyzed both the elemental concentration and isotope ratios of Sr and Pb from four different women of different ages to monitor their permanent relocation from central France to Eastern Canada during the summer 2012. For comparison, we also characterized bulk hair samples of sedentary individuals and local tap waters from their regions of origin and of settlement. Our results indicate that the 87Sr/86Sr and 206Pb/204Pb ratios are significantly modified by the change of environment, but also confirm that human hair compositions are impacted by other external factors (such as dust). Sr and Pb isotope systematics demonstrate their added value for detecting human mobility, but require further studies to better constrain the main sources and processes controlling their respective budgets in human hair for provenancing purposes. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

  3. Isotopic Compositions of the Elements 1997

    Science.gov (United States)

    Rosman, K. J. R.; Taylor, P. D. P.

    1998-11-01

    The Commission's Subcommittee for the Isotopic Composition of the Elements has carried out its biennial review of isotopic compositions, as determined by mass spectrometry and other relevant methods. This involves a critical evaluation of the published literature, element by element, and forms the basis of the Table of Isotopic Compositions of the Elements as Determined by Mass Spectrometry presented here. New guidelines have been used to arrive at the uncertainties on the isotopic abundances and there are numerous changes to the table since it was last published in 1991. Atomic Weights calculated from this table are consistent with Ar(E) values listed in the Table of Standard Atomic Weights 1997.

  4. Stable isotope labeling methods for DNA.

    Science.gov (United States)

    Nelissen, Frank H T; Tessari, Marco; Wijmenga, Sybren S; Heus, Hans A

    2016-08-01

    NMR is a powerful method for studying proteins and nucleic acids in solution. The study of nucleic acids by NMR is far more challenging than for proteins, which is mainly due to the limited number of building blocks and unfavorable spectral properties. For NMR studies of DNA molecules, (site specific) isotope enrichment is required to facilitate specific NMR experiments and applications. Here, we provide a comprehensive review of isotope-labeling strategies for obtaining stable isotope labeled DNA as well as specifically stable isotope labeled building blocks required for enzymatic DNA synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Isotopic investigation of an Australian island environment

    Energy Technology Data Exchange (ETDEWEB)

    Groecke, D.R. [Australian National Univ., Canberra, ACT (Australia). Research School of Earth Sciences; Bocherens, H. [Paris-6 Univ., 75 (France)

    1996-12-31

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

  6. N and O isotope effects during nitrate assimilation by unicellular prokaryotic and eukaryotic plankton cultures

    Science.gov (United States)

    Granger, J.; Sigman, D. M.; Rohde, M. M.; Maldonado, M. T.; Tortell, P. D.

    2010-02-01

    In order to provide biological systematics from which to interpret nitrogen (N) and oxygen (O) isotope ratios of nitrate ( 15N/ 14N, 18O/ 16O, respectively) in the environment, we previously investigated the isotopic fractionation of nitrate during its assimilation by mono-cultures of eukaryotic algae ( Granger et al., 2004). In this study, we extended our analysis to investigate nitrate assimilation by strains of prokaryotic plankton. We measured the N and O isotope effects, 15ɛ and 18ɛ, during nitrate consumption by cultures of prokaryotic strains and by additional eukaryotic phytoplankton strains (where ɛ is the ratio of reaction rate constants of the light vs. heavy isotopologues, lightk and heavyk; ɛ = lightk/ heavyk - 1 × 1000, expressed in per mil). The observed 15ɛ ranged from 5‰ to 8‰ among eukaryotes, whereas it did not exceed 5‰ for three cyanobacterial strains, and was as low as 0.4‰ for a heterotrophic α-protoeobacterium. Eukaryotic phytoplankton fractionated the N and O isotopes of nitrate to the same extent (i.e., 18ɛ ˜ 15ɛ). The 18ɛ: 15ɛ among the cyanobacteria was also ˜1, whereas the heterotrophic α-proteobacterial strain, which showed the lowest 15ɛ, between 0.4‰ and 1‰, had a distinct 18ɛ: 15ɛ of ˜2, unlike any plankton strain observed previously. Equivalent N vs. O isotope discrimination is thought to occur during internal nitrate reduction by nitrate reductase, such that the cellular efflux of the fractionated nitrate into the medium drives the typically observed 18ɛ: 15ɛ of ˜1. We hypothesize that the higher in the 18ɛ: 15ɛ of the α-proteobacterium may result from isotope discrimination by nitrate transport, which is evident only at low amplitude of ɛ. These observations warrant investigating whether heterotrophic bacterial assimilation of nitrate decreases the community isotope effects at the surface ocean.

  7. Cu-Zn-Pb multi isotopic characterization of a small watershed (Loire river basin, France)

    Science.gov (United States)

    Desaulty, A. M.; Millot, R.; Perret, S.; Bourrain, X.

    2015-12-01

    Combating metal pollution in surface water is a major environmental, public health and economic issue. Knowledge of the behavior of metals, such as copper (Cu), zinc (Zn) and lead (Pb) in sediments and dissolved load, is a key factor to improve the management of rivers. Recent advances in mass spectrometry related to the development of MC-ICPMS allow to analyze the isotopic composition of these elements, and previous studies show the effectiveness of isotopic analyses to determine the anthropogenic sources of pollution in environment. The goal of this study is to use the Cu-Zn-Pb multi-isotopic signature to track the pollutions in surface water, and to understand the complex processes causing the metals mobilization and transport in environment. More particularly we investigate the mechanisms of distribution between the dissolved load and particulate load, known to play an important role in the transport of metals through river systems. As case study, we chose a small watershed, poorly urbanized in the Loire river basin. Its spring is in a pristine area, while it is only impacted some kilometers further by the releases rich in metals coming from a hospital water treatment plant. First a sampling of these liquid effluents as well as dissolved load and sediment from upstream to downstream was realized and their concentrations and isotopic data were determined. Then to simulate a lot of potential natural and anthropogenic modifications of environmental conditions, we made sequential extraction protocol using various reagents on the sediments. Isotopic analyzes were performed also on the various extracting solutions. Isotopic ratios were measured using a Neptune MC-ICPMS at the BRGM, after a protocol of purification for Zn and Cu. The results showed that, these isotopic systematics reveal important informations about the mechanists of mobilization and transport of metals through river systems. However experiments performed under laboratory conditions will be necessary

  8. Building materials as intrinsic sources of sulphate: A hidden face of salt weathering of historical monuments investigated through multi-isotope tracing (B, O, S)

    Energy Technology Data Exchange (ETDEWEB)

    Kloppmann, W., E-mail: w.kloppmann@brgm.fr [BRGM, BP 6009, F-45060 Orleans cedex 2 (France); Bromblet, P.; Vallet, J.M. [CICRP, 21, rue Guibal, F-13003 Marseille (France); Verges-Belmin, V. [LRMH, 29, rue de Paris, F-77420 Champs sur Marne (France); Rolland, O. [Independent restorer, 3, rue du Gue, 37270 Montlouis s/Loire (France); Guerrot, C. [BRGM, BP 6009, F-45060 Orleans cedex 2 (France); Gosselin, C. [BRGM, BP 6009, F-45060 Orleans cedex 2 (France); LRMH, 29, rue de Paris, F-77420 Champs sur Marne (France)

    2011-04-01

    Sulphate neoformation is a major factor of degradation of stone monuments. Boron, sulphur and oxygen isotope signatures were investigated for five French historical monuments (Bourges, Chartres and Marseille cathedrals, Chenonceau castle, and Versailles garden statues) to investigate the role of intrinsic sulphate sources (gypsum plasters and mortars) in stone degradation, compared to the influence of extrinsic sources such as atmospheric pollution. Gypsum plasters and gypsum-containing mortars fall systematically in the {delta}{sup 34}S and {delta}{sup 18}O range of Paris Basin Eocene evaporites indicating the origin of the raw materials (so-called 'Paris plaster'). Black crusts show the typical S and O isotope signatures observed elsewhere in Europe that can be attributed to atmospheric pollution, together with a marine component for Marseille. Boron isotopes for black crusts indicate coal combustion as principal boron source. Mortar isotope compositions discriminate three types, one similar to gypsum plasters, one strongly depleted in {sup 34}S, attributed to pyrite oxidation, and a third one close to atmospheric sulphates. The isotopic composition of sulphates and boron of most degraded building stones of the different monuments is well explained by the identified sulphate sources. In several cases (in particular for Chenonceau and Bourges, to some extent for Chartres), the impact of gypsum plaster as building and restoration material on the degradation of the stones in its vicinity was clearly demonstrated. The study illustrates the usefulness of multi-isotope studies to investigate stone degradation factors, as the combination of several isotope systematics increases the discriminatory power of isotope studies with respect to contaminant sources. - Research Highlights: {yields} Insight in stone weathering mechanisms by multi-isotope fingerprinting (B, S, O). {yields} Intrinsic sulphate sources (gypsum plaster, mortar) contribute to stone degradation

  9. Tracking along-arc sediment inputs to the Aleutian arc using thallium isotopes

    Science.gov (United States)

    Nielsen, Sune G.; Yogodzinski, Gene; Prytulak, Julie; Plank, Terry; Kay, Suzanne M.; Kay, Robert W.; Blusztajn, Jerzy; Owens, Jeremy D.; Auro, Maureen; Kading, Tristan

    2016-05-01

    Sediment transport from the subducted slab to the mantle wedge is an important process in understanding the chemical and physical conditions of arc magma generation. The Aleutian arc offers an excellent opportunity to study sediment transport processes because the subducted sediment flux varies systematically along strike (Kelemen et al., 2003) and many lavas exhibit unambiguous signatures of sediment addition to the sub-arc mantle (Morris et al., 1990). However, the exact sediment contribution to Aleutian lavas and how these sediments are transported from the slab to the surface are still debated. Thallium (Tl) isotope ratios have great potential to distinguish sediment fluxes in subduction zones because pelagic sediments and low-temperature altered oceanic crust are highly enriched in Tl and display heavy and light Tl isotope compositions, respectively, compared with the upper mantle and continental crust. Here, we investigate the Tl isotope composition of lavas covering almost the entire Aleutian arc a well as sediments outboard of both the eastern (DSDP Sites 178 and 183) and central (ODP Hole 886C) portions of the arc. Sediment Tl isotope compositions change systematically from lighter in the Eastern to heavier in the Central Aleutians reflecting a larger proportion of pelagic sediments when distal from the North American continent. Lavas in the Eastern and Central Aleutians mirror this systematic change to heavier Tl isotope compositions to the west, which shows that the subducted sediment composition is directly translated to the arc east of Kanaga Island. Moreover, quantitative mixing models of Tl and Pb, Sr and Nd isotopes reveal that bulk sediment transfer of ∼0.6-1.0% by weight in the Eastern Aleutians and ∼0.2-0.6% by weight in the Central Aleutians can account for all four isotope systems. Bulk mixing models, however, require that fractionation of trace element ratios like Ce/Pb, Cs/Tl, and Sr/Nd in the Central and Eastern Aleutians occurs after

  10. Tungsten isotopes and the origin of the Moon

    Energy Technology Data Exchange (ETDEWEB)

    Kruijer, Thomas S.; Kleine, Thorsten

    2017-10-01

    The giant impact model of lunar origin predicts that the Moon mainly consists of impactor material. As a result, the Moon is expected to be isotopically distinct from the Earth, but it is not. To account for this unexpected isotopic similarity of the Earth and Moon, several solutions have been proposed, including (i) post-giant impact Earth–Moon equilibration, (ii) alternative models that make the Moon predominantly out of proto-Earth mantle, and (iii) formation of the Earth and Moon from an isotopically homogeneous disk reservoir. Here we use W isotope systematics of lunar samples to distinguish between these scenarios. We report high-precision 182W data for several low-Ti and high-Ti mare basalts, as well as for Mg-suite sample 77215, and lunar meteorite Kalahari 009, which complement data previously obtained for KREEP-rich samples. In addition, we utilize high-precision Hf isotope and Ta/W ratio measurements to empirically quantify the superimposed effects of secondary neutron capture on measured 182W compositions. Our results demonstrate that there are no resolvable radiogenic 182W variations within the Moon, implying that the Moon differentiated later than 70 Ma after Solar System formation. In addition, we find that samples derived from different lunar sources have indistinguishable 182W excesses, confirming that the Moon is characterized by a small, uniform ~+26 parts-per-million excess in 182W over the present-day bulk silicate Earth. This 182W excess is most likely caused by disproportional late accretion to the Earth and Moon, and after considering this effect, the pre-late veneer bulk silicate Earth and the Moon have indistinguishable 182W compositions. Mixing calculations demonstrate that this Earth–Moon 182W similarity is an unlikely outcome of the giant impact, which regardless of the amount of impactor material incorporated into the Moon should have generated a significant 182W excess in the Moon. Consequently, our results imply that post

  11. Nitrate dynamics in natural plants: Insights based on the concentration and natural isotope abundances of tissue nitrate

    Directory of Open Access Journals (Sweden)

    Xue Yan Liu

    2014-07-01

    Full Text Available The dynamics of nitrate (NO3-, a major nitrogen (N source for natural plants, has been studied mostly through experimental N addition, enzymatic assay, isotope labeling, and genetic expression. However, artificial N supply may not reasonably reflect the N strategies in natural plants because NO3- uptake and reduction may vary with external N availability. Abrupt application and short operation times, field N addition, and isotopic labeling hinder the elucidation of in situ NO3--use mechanisms. The concentration and natural isotopes of tissue NO3- can offer insights into the plant NO3- sources and dynamics in a natural context. Furthermore, they facilitate the exploration of plant NO3- utilization and its interaction with N pollution and ecosystem N cycles without disturbing the N pools. The present study was conducted to review the application of the denitrifier method for concentration and isotope analyses of NO3- in plants. Moreover, this study highlights the utility and benefits of these parameters in interpreting NO3- sources and dynamics in natural plants. We summarize the major sources and reduction processes of NO3- in plants, and discuss the implications of NO3- concentration in plant tissues based on existing data. Particular emphasis was laid on the regulation of soil NO3 - and plant ecophysiological functions in interspecific and intra-plant NO3- variations. We introduce N and O isotope systematics of NO3- in plants and discusse the principles and feasibilities of using isotopic enrichment and fractionation factors; the correlation between concentration and isotopes (N and O isotopes: δ18O and ∆17O; and isotope mass-balance calculations to constrain sources and reduction of NO3- in possible scenarios for natural plants are deliberated. Finally, we construct a preliminary framework of intraplant δ18O-NO3- variation, and summarize the uncertainties in using tissue NO3- parameters to interpret plant NO3- utilization.

  12. Multi isotopic characterization (Li-Cu-Zn-Pb) of waste waters pollution in a small watershed (Loire River basin, France)

    Science.gov (United States)

    Millot, R.; Desaulty, A. M.; Perret, S.; Bourrain, X.

    2016-12-01

    The goal of this study is to use multi-isotopic signature to track the pollution in surface waters, and to understand the complex processes causing the metals mobilization and transport in the environment. In the present study, we investigate waste water releases from a hospital water treatment plant and its potential impact in a small river basin near Orléans in France (Egoutier watershed: 15 km²and 5 km long). We decided to monitor this small watershed which is poorly urbanized in the Loire river basin. Its spring is located in a pristine area (forested area), while it is only impacted some kilometers further by the releases rich in metals coming from a hospital water treatment plant. A sampling of these liquid effluents as well as dissolved load and sediment from upstream to downstream was realized and their concentrations and isotopic data were determined. Isotopic ratios were measured using a MC-ICP-MS at BRGM, after a specific protocol of purification for each isotopic systematics. Lithium isotopic compositions are rather homogeneous in river waters along the main course of the stream. The waste water signal is very different from the natural background with significant heavy lithium contribution (high δ7Li). Lead isotopic compositions are rather homogenous in river waters and sediments with values close to geologic background. For Zn, the sediments with high concentrations and depleted isotopic compositions (low δ66Zn), typical of an anthropic pollution, are strongly impacted. The analyses of Cu isotopes in sediments show the impact of waster waters, but also isotopic fractionations due to redox processes in the watershed. To better understand these processes controlling the release of metals in water, sequential extractions on sediments are in progress under laboratory conditions and will provide important constraints for metal distribution in this river basin.

  13. SWING - The Stable Water Isotope Intercomparison Group

    Science.gov (United States)

    Werner, M.; Barras, V.; Brown, J.; Gourcy, L.; Henderson-Sellers, A.; Hoffmann, G.; Ichiyanagi, K.; Kelley, M.; Noone, D.; Roads, J.; Schmidt, G.; Sturm, K.; Tindall, J.; Valdes, P.; Yoshimura, K.; Zakharov, V.

    2004-12-01

    For more than four decades the isotopic composition of water stored in various archives (e.g. ice cores, ground water) has been used to study changes in the hydrological cycle on timescales from glacial-interglacial to short term variations. However, the interpretation of isotopic variations in terms of climate change is often handicapped by a lack of other relevant observational climate parameters (e.g. temperature, relative humidity, precipitation) both in space and time. Modeling the isotopic composition of water within the hydrological cycle of general circulation models (GCM) may help to overcome this deficit on available climate data. Isotope GCMs simulate the 18O/16O (and/or 2H/1H) relation as an independent quantity within a closed "model world" where all other relevant climate parameters are known, too. This enables an improved analysis of (simulated) isotope variability in terms of climate change and during the last decade several state-of-the-art GCM models (GISS, ECHAM, LMD, GENESIS and others) have been enhanced by the capability to simulate the atmospheric and/or ocean cycle of H218O and 1H2H16O. To ensure isotope GCM reliability, any isotope GCM simulation must pass a rigorous comparison of simulated versus observed isotope data (model-data-intercomparison). In addition, artifacts in isotope simulations based on a specific GCM model parameterization or set-up have to be identified by comparing simulation results of several different isotope GCMs (model-model intercomparison). In our presentation we will give an overview and first results of the SWING project, founded in 2004. This initiative serves as a community platform for experts from the various isotope research groups and has the following objectives: (1) enable an overview about ongoing isotope GCM modeling capabilities; (2) define and perform future common GCM isotope simulation experiments of the various research groups; (3) identify the most important need of new observational isotope data

  14. Investigations of the Hydrologic Cycle in the Arctic Climate System Using Water Isotopes

    Science.gov (United States)

    Kopec, Ben Gordon

    Warming has caused widespread changes to the Arctic hydrologic cycle, indicated by sea ice reductions, the Greenland Ice Sheet (GIS) mass loss, and permafrost degradation. Understanding Arctic hydrologic processes is essential for quantifying hydrological responses to climate change. A valuable tool to study these responses is the hydrogen and oxygen isotope ratios of water. Studies presented here aim to both innovatively apply water isotopes with existing understanding, and gain new knowledge in isotope systematics. I present several studies here. First, I show that Arctic precipitation increases with enhanced evaporation due to sea ice reduction; each 100,000 km2 loss in sea ice area increases the fraction of Arctic sourced moisture in total precipitation by 11 to 18%. Second, I argue that vapor sublimated from the GIS significantly contributes to summer precipitation at Summit, Greenland. This conclusion is first supported by isotopic variations in the daily precipitation collected at Summit for three years, and then further verified by 30 annual isotopic cycles in a shallow ice core. The result is not only important for quantifying the current ice sheet mass balance, but also for inferences of paleoclimate from ice cores. Third, I demonstrate that local scale atmospheric circulation in the glacier-free strip of West Greenland is dominated by convergence of dry glacial air masses from the east and moist marine air masses from the west. The dynamics of this convergence are affected by both regional radiation balance differences and broader circulation patterns such as the North Atlantic Oscillation. Humidity variations associated with these air masses control local precipitation and lake evaporation. Finally, along the east-west moisture gradient in West Greenland, lake evaporation also exhibits systematic changes in rate and isotopic enrichment, a result that is important for lake sediment core research. I have made advances in understanding water isotope

  15. POLONIUM-194 and the Onset of Collectivity in the Polonium Isotopes.

    Science.gov (United States)

    Younes, Walid

    This dissertation presents the results of the experimental measurement of ^{194}Po , the lightest Polonium isotope studied to date. The systematical behavior of even-A Polonium isotopes down to A = 194 is interpreted within both phenomenological and theoretical frameworks. The heavy-ion reaction ^{28 }Si + ^{170}Yb, was used to form ^{194}Po. The experiment was carried out at the Argonne Tandem-Linac System (ATLAS), which provided a 142 MeV ^ {28}Si ion beam. The Fragment Mass Analyzer (FMA) was used to identify A = 194 recoils. An array of ten Compton-suppressed Ge detectors was used to measure the prompt, in-beam gamma rays. Drawing on a combination of FMA-gamma and FMA-gamma-gamma coincidence data, eight gamma rays were assigned to ^{194}Po and placed in a decay scheme consisting of a six-transition yrast cascade and two non-yrast states. Spin and parity assignments were made based on the systematics of heavier Polonium isotopes. Comparison with the systematics of other nuclei with two valence protons suggests that the onset of collective behavior in these isotopes occurs when both types of valence nucleons occupy high-j orbitals. The underlying mechanism which favors high-j orbitals was explained using naive semiclassical angular overlap arguments. The Particle -Core Model (PCM) was then applied to the Polonium isotopes to isolate the single-particle and vibrational degrees of freedom, and provide a quantitative description of the transition between these extremes. The PCM wavefunctions of low-lying states were found to be pure for A > 198, and increasingly mixed between states with different number of phonons for the lighter isotopes. The Quasiparticle Random Phase Approximation (QRPA) was used to extract the neutron configuration of the PCM phonons. The rapid onset of collectivity for A < 200 could then be explained in terms of the opening of the neutron i_{13/2} orbital and the resulting enhanced overlap with the proton (h _{9/2})^2 configuration. The

  16. The early bird gets the shrimp: confronting assumptions of isotopic equilibrium and homogeneity in a wild bird population.

    Science.gov (United States)

    Wunder, Michael B; Jehl, Joseph R; Stricker, Craig A

    2012-11-01

    1. Because stable isotope distributions in organic material vary systematically across energy gradients that exist in ecosystems, community and population structures, and in individual physiological systems, isotope values in animal tissues have helped address a broad range of questions in animal ecology. It follows that every tissue sample provides an isotopic profile that can be used to study dietary or movement histories of individual animals. Interpretations of these profiles depend on the assumption that metabolic pools are isotopically well mixed and in equilibrium with dietary resources prior to tissue synthesis, and they extend to the population level by assuming isotope profiles are identically distributed for animals using the same proximal dietary resource. As these assumptions are never fully met, studying structure in the variance of tissue isotope values from wild populations is informative. 2. We studied variation in δ(13) C, δ(15) N, δ(2) H and δ(18) O data for feathers from a population of eared grebes (Podiceps nigricollis) that migrate to Great Salt Lake each fall to moult feathers. During this time, they cannot fly and feed almost exclusively on superabundant brine shrimp (Artemia franciscana). The ecological simplicity of this situation minimized the usual spatial and trophic complexities often present in natural studies of feather isotope values. 3. Ranges and variances of isotope values for the feathers were larger than those from previously published studies that report feather isotopic variance, but they were bimodally distributed in all isotope dimensions. Isotope values for proximal dietary resources and local surface water show that some of the feathers we assumed to have been grown locally must have been grown before birds reached isotopic equilibrium with local diet or immediately prior to arrival at Great Salt Lake. 4. Our study provides novel insights about resource use strategies in eared grebes during migration. More generally

  17. Selected scientific topics of the 11th International Isotope Symposium on the Synthesis and Applications of Isotopes and Isotopically Labeled Compounds.

    Science.gov (United States)

    Atzrodt, Jens; Derdau, Volker

    2013-01-01

    This micro-review describes hot topics and new trends in isotope science discussed at the 11th International Isotope Symposium on the Synthesis and Applications of Isotopes and Isotopically Labeled Compounds from a personal perspective. Copyright © 2013 John Wiley & Sons, Ltd.

  18. physico-chemical and stable isotopes

    African Journals Online (AJOL)

    This paper details the mineralogical, chemical and stable isotope abundances of calcrete in the Letlhakeng fossil valley. The stable isotope abundances (O and C) of calcretes yielded some values which were tested against the nature of the calcretes – pedogenic or groundwater type. The Kgalagadi (Kalahari) is a vast ...

  19. Advanced Mass Spectrometers for Hydrogen Isotope Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Chastagner, P.

    2001-08-01

    This report is a summary of the results of a joint Savannah River Laboratory (SRL) - Savannah River Plant (SRP) ''Hydrogen Isotope Mass Spectrometer Evaluation Program''. The program was undertaken to evaluate two prototype hydrogen isotope mass spectrometers and obtain sufficient data to permit SRP personnel to specify the mass spectrometers to replace obsolete instruments.

  20. Dual Carbon and Nitrogen Isotope Analysis

    African Journals Online (AJOL)

    According to Hemminga & Mateo. (1996), values of carbon and nitrogen isotope ratios vary considerably between seagrass species. It might also be expected that the remaining seagrass species could have some influence on the shrimp carbon signal. Isotopic evidence for mangroves being a carbon source for shrimps ...

  1. Isotopic niches support the resource breadth hypothesis.

    Science.gov (United States)

    Rader, Jonathan A; Newsome, Seth D; Sabat, Pablo; Chesser, R Terry; Dillon, Michael E; Martínez Del Rio, Carlos

    2017-03-01

    Because a broad spectrum of resource use allows species to persist in a wide range of habitat types, and thus permits them to occupy large geographical areas, and because broadly distributed species have access to more diverse resource bases, the resource breadth hypothesis posits that the diversity of resources used by organisms should be positively related with the extent of their geographic ranges. We investigated isotopic niche width in a small radiation of South American birds in the genus Cinclodes. We analysed feathers of 12 species of Cinclodes to test the isotopic version of the resource breadth hypothesis and to examine the correlation between isotopic niche breadth and morphology. We found a positive correlation between the widths of hydrogen and oxygen isotopic niches (which estimate breadth of elevational range) and widths of the carbon and nitrogen isotopic niches (which estimates the diversity of resources consumed, and hence of habitats used). We also found a positive correlation between broad isotopic niches and wing morphology. Our study not only supports the resource breadth hypothesis but it also highlights the usefulness of stable isotope analyses as tools in the exploration of ecological niches. It is an example of a macroecological application of stable isotopes. It also illustrates the importance of scientific collections in ecological studies. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

  2. Isotopic niches support the resource breadth hypothesis

    Science.gov (United States)

    Rader, Jonathan A.; Newsome, Seth D.; Sabat, Pablo; Chesser, R. Terry; Dillon, Michael E.; Martinez del Rio, Carlos

    2017-01-01

    Because a broad spectrum of resource use allows species to persist in a wide range of habitat types, and thus permits them to occupy large geographical areas, and because broadly distributed species have access to more diverse resource bases, the resource breadth hypothesis posits that the diversity of resources used by organisms should be positively related with the extent of their geographic ranges.We investigated isotopic niche width in a small radiation of South American birds in the genus Cinclodes. We analysed feathers of 12 species of Cinclodes to test the isotopic version of the resource breadth hypothesis and to examine the correlation between isotopic niche breadth and morphology.We found a positive correlation between the widths of hydrogen and oxygen isotopic niches (which estimate breadth of elevational range) and widths of the carbon and nitrogen isotopic niches (which estimates the diversity of resources consumed, and hence of habitats used). We also found a positive correlation between broad isotopic niches and wing morphology.Our study not only supports the resource breadth hypothesis but it also highlights the usefulness of stable isotope analyses as tools in the exploration of ecological niches. It is an example of a macroecological application of stable isotopes. It also illustrates the importance of scientific collections in ecological studies.

  3. Atomic lithium vapor laser isotope separation

    CERN Document Server

    Olivares, I E

    2002-01-01

    An atomic vapor laser isotope separation in lithium was performed using tunable diode lasers. The method permits also the separation of the isotopes between the sup 6 LiD sub 2 and the sup 7 LiD sub 1 lines using a self-made mass separator which includes a magnetic sector and an ion beam designed for lithium. (Author)

  4. The isotopic dipole moment of HDO

    Energy Technology Data Exchange (ETDEWEB)

    Assafrao, Denise; Mohallem, Jose R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, CP 702, 30123-970, Belo Horizonte, MG (Brazil)

    2007-03-14

    An adiabatic variational approximation is used to study the monodeuterated water molecule, HDO, accounting for the isotopic effect. The isotopic dipole moment, pointing from D to H, is then calculated for the first time, yielding (1.5 {+-} 0.1) x 10{sup -3} Debye, being helpful in the interpretation of experiments. (fast track communication)

  5. Environmental isotopes investigation in groundwater of Challaghatta ...

    African Journals Online (AJOL)

    Radiogenic isotopes (3H and 14C) and stable isotope (18O) together with TDS, EC and salinity of water were used to discriminate qualitative and quantitative groundwater age, probable recharge time, flow respectively in groundwater of Challaghatta valley, Bangalore. The variations between TDS and EC values of sewage ...

  6. Isotope Program Report June FY2016

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Jr, Benjamin E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Egle, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-01

    Isotope Program Monthly Highlights are briefly described. These include data on isotopes shipped, updates on equipment fabrication and testing, a potential new approach for nondestructive measurement of the amount of Cf-252 deposited on a surface, and efforts to recover and purify uranium-234 obtained from old PuBe sources.

  7. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 8. Use of Isotopes for Studying Reaction Mechanisms-Secondary Kinetic Isotope Effect. Uday Maitra J Chandrasekhar. Series Article Volume 2 Issue 8 August 1997 pp 18-25 ...

  8. Tracing thallium contamination in soils using isotopes

    Science.gov (United States)

    Vaněk, Aleš; Grösslová, Zuzana; Mihaljevič, Martin; Ettler, Vojtěch; Trubač, Jakub; Teper, Leslaw; Cabala, Jerzy; Rohovec, Jan; Penížek, Vít; Zádorová, Tereza; Pavlů, Lenka; Holubík, Ondřej; Drábek, Ondřej; Němeček, Karel; Houška, Jakub; Ash, Christopher

    2017-04-01

    We report the thallium (Tl) isotope record in moderately contaminated soils, which have been historically affected by emissions from coal-fired power plants. Our findings clearly demonstrate that Tl of anthropogenic (high-temperature) origin with light isotope composition was deposited onto the studied soils, where heavier Tl (ɛ205Tl -1) naturally occurs. The results show a positive linear relationship (R2 = 0.71) between 1/Tl and the isotope record, as determined for all the soils and bedrocks, also indicative of binary Tl mixing between two dominant reservoirs. We also identified significant Tl isotope variations within the products from coal combustion and thermo-desorption experiments with local Tl-rich coal pyrite. Bottom ash exhibited the heaviest Tl isotope composition (ɛ205Tl 0), followed by fly ash (ɛ205Tl between -2.5 and -2.8) and volatile Tl fractions (ɛ205Tl between -6.2 and -10.3), suggesting partial Tl isotope fractionations. Despite the evident role of soil processes in the isotope redistribution, we demonstrate that Tl contamination can be traced in soils, and propose that the isotope data represent a possible tool to aid our understanding of post-depositional Tl dynamics in surface environments for the future. This research was supported by the Czech Science Foundation (grant no. 14-01866S and 17-03211S).

  9. Correction of MS data for naturally occurring isotopes in isotope labelling experiments.

    Science.gov (United States)

    Millard, Pierre; Letisse, Fabien; Sokol, Serguei; Portais, Jean-Charles

    2014-01-01

    Mass spectrometry (MS) in combination with isotope labelling experiments is widely used for investigations of metabolism and other biological processes. Quantitative applications-e.g., (13)C metabolic flux analysis-require correction of raw MS data (isotopic clusters) for the contribution of all naturally abundant isotopes. This chapter describes how to perform such correction using the software IsoCor. This flexible, user-friendly software can be used to exploit any isotopic tracer, from well-known ((13)C, (15)N, (18)O, etc.) to unusual ((57)Fe, (77)Se, etc.) isotopes. It also provides options-e.g., correction for the isotopic purity of the tracer-to improve the accuracy of quantitative isotopic studies, and allows automated correction of large datasets that can be collected with modern MS methods.

  10. Nitrogen isotope composition of organically and conventionally grown crops.

    Science.gov (United States)

    Bateman, Alison S; Kelly, Simon D; Woolfe, Mark

    2007-04-04

    Authentic samples of commercially produced organic and conventionally grown tomatoes, lettuces, and carrots were collected and analyzed for their delta15N composition in order to assemble datasets to establish if there are any systematic differences in nitrogen isotope composition due to the method of production. The tomato and lettuce datasets suggest that the different types of fertilizer commonly used in organic and conventional systems result in differences in the nitrogen isotope composition of these crops. A mean delta15N value of 8.1 per thousand was found for the organically grown tomatoes compared with a mean value of -0.1 per thousand for those grown conventionally. The organically grown lettuces had a mean value of 7.6 per thousand compared with a mean value of 2.9 per thousand for the conventionally grown lettuces. The mean value for organic carrots was not significantly different from the mean value for those grown conventionally. Overlap between the delta15N values of the organic and conventional datasets (for both tomatoes and lettuces) means that it is necessary to employ a statistical methodology to try and classify a randomly analyzed "off the shelf" sample as organic/conventional, and such an approach is demonstrated. Overall, the study suggests that nitrogen isotope analysis could be used to provide useful "intelligence" to help detect the substitution of certain organic crop types with their conventional counterparts. However, delta15N analysis of a "test sample" will not provide unequivocal evidence as to whether synthetic fertilizers have been used on the crop but could, for example, in a situation when there is suspicion that mislabeling of conventionally grown crops as "organic" is occurring, be used to provide supporting evidence.

  11. Second international conference on isotopes. Conference proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, C.J. [ed.

    1997-10-01

    The Second International Conference on Isotopes (2ICI) was hosted by the Australian Nuclear Association in Sydney, NSW, Australia. The Theme of the Second Conference: Isotopes for Industry, Health and a Better Environment recognizes that isotopes have been used in these fields successfully for many years and offer prospects for increasing use in the future. The worldwide interest in the use of research reactors and accelerators and in applications of stable and radioactive isotopes, isotopic techniques and radiation in industry, agriculture, medicine, environmental studies and research in general, was considered. Other radiation issues including radiation protection and safety were also addressed. International and national overviews and subject reviews invited from leading experts were included to introduce the program of technical sessions. The invited papers were supported by contributions accepted from participants for oral and poster presentation. A Technical Exhibition was held in association with the Conference. This volume contains the full text or extended abstracts of papers number 61- to number 114

  12. Selected Isotopes for Optimized Fuel Assembly Tags

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-10-01

    In support of our ongoing signatures project we present information on 3 isotopes selected for possible application in optimized tags that could be applied to fuel assemblies to provide an objective measure of burnup. 1. Important factors for an optimized tag are compatibility with the reactor environment (corrosion resistance), low radioactive activation, at least 2 stable isotopes, moderate neutron absorption cross-section, which gives significant changes in isotope ratios over typical fuel assembly irradiation levels, and ease of measurement in the SIMS machine 2. From the candidate isotopes presented in the 3rd FY 08 Quarterly Report, the most promising appear to be Titanium, Hafnium, and Platinum. The other candidate isotopes (Iron, Tungsten, exhibited inadequate corrosion resistance and/or had neutron capture cross-sections either too high or too low for the burnup range of interest.

  13. Oxygen isotope fractionation in stratospheric CO2

    Science.gov (United States)

    Thiemens, M. H.; Jackson, T.; Mauersberger, K.; Schueler, B.; Morton, J.

    1991-01-01

    A new cryogenic collection system has been flown on board a balloon gondola to obtain separate samples of ozone and carbon dioxide without entrapping major atmospheric gases. Precision laboratory isotopic analysis of CO2 samples collected between 26 and 35.5 km show a mass-independent enrichment in both O-17 and O-18 of about 11 per mil above tropospheric values. Ozone enrichment in its heavy isotopes was 9 to 16 percent in O3-50 and 8 to 11 percent in O3-49, respectively (Schueler et al., 1990). A mechanism to explain the isotope enrichment in CO2 has been recently proposed by Yung et al. (1991). The model is based on the isotope exchange between CO2 and O3 via O(1D), resulting in a transfer of the ozone isotope enrichment to carbon dioxide. Predicted enrichment and measured values agree well.

  14. Nitrogen and carbon isotope variability in the green-algal lichen Xanthoria parietina and their implications on mycobiont–photobiont interactions

    Science.gov (United States)

    Beck, Andreas; Mayr, Christoph

    2012-01-01

    Stable isotope patterns in lichens are known to vary largely, but effects of substrate on carbon and nitrogen stable isotope signatures of lichens were previously not investigated systematically. N and C contents and stable isotope (δ15N, δ13C) patterns have been measured in 92 lichen specimens of Xanthoria parietina from southern Bavaria growing on different substrates (bark and stone). Photobiont and mycobiont were isolated from selected populations and isotopically analyzed. Molecular investigations of the internal transcribed spacer of the nuclear ribosomal DNA (ITS nrDNA) region have been conducted on a subset of the specimens of X. parietina. Phylogenetic analysis showed no correlation between the symbionts X. parietina and Trebouxia decolorans and the substrate, isotope composition, or geographic origin. Instead specimens grown on organic substrate significantly differ in isotope values from those on minerogenic substrate. This study documents that the lichens growing on bark use additional or different N sources than the lichens growing on stone. δ15N variation of X. parietina apparently is controlled predominantly by the mass fraction of the mycobiont and its nitrogen isotope composition. In contrast with mycobionts, photobionts of X. parietina are much more 15N-depleted and show less isotopic variability than mycobionts, probably indicating a mycobiont-independent nitrogen acquisition by uptake of atmospheric ammonia. PMID:23301178

  15. Manus Water Isotope Investigation Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Conroy, Jessica L [University of Illinois, Urbana-Champaign; Cobb, Kim M [Georgia Institute of Technology; Noone, David [University of Colorado, Boulder

    2016-03-01

    The objective of this field campaign was to investigate climatic controls on the stable isotopic composition of water vapor, precipitation, and seawater in the western tropical Pacific. Simultaneous measurements of the stable isotopic composition of vapor and precipitation from April 28 to May 8, 2013, at the Manus Tropical Western Pacific Atmospheric Radiation Measurement site, provided several key insights into the nature of the climate signal archived in precipitation and vapor isotope ratios. We observed a large shift from lower to higher isotopic values in vapor and precipitation because of the passage of a mesoscale convective system west of the site and a transition from a regional stormy period into a more quiescent period. During the quiescent period, the stable isotopic composition of vapor and precipitation indicated the predominance of oceanic evaporation in determining the isotopic composition of boundary-layer vapor and local precipitation. There was not a consistent relationship between intra-event precipitation amount at the site and the stable isotopic composition of precipitation, thus challenging simplified assumptions about the isotopic “amount effect” in the tropics on the time scale of individual storms. However, some storms did show an amount effect, and deuterium excess values in precipitation had a significant relationship with several meteorological variables, including precipitation, temperature, relative humidity, and cloud base height across all measured storms. The direction of these relationships points to condensation controls on precipitation deuterium excess values on intra-event time scales. The relationship between simultaneous measurements of vapor and precipitation isotope ratios during precipitation events indicates the ratio of precipitation-to-vapor isotope ratios can diagnose precipitation originating from a vapor source unique from boundary-layer vapor and rain re-evaporation.

  16. Delayed Particle Study of Neutron Rich Lithium Isotopes

    CERN Multimedia

    Marechal, F; Perrot, F

    2002-01-01

    We propose to make a systematic complete coincidence study of $\\beta$-delayed particles from the decay of neutron-rich lithium isotopes. The lithium isotopes with A=9,10,11 have proven to contain a vast information on nuclear structure and especially on the formation of halo nuclei. A mapping of the $\\beta$-strength at high energies in the daughter nucleus will make possible a detailed test of our understanding of their structure. An essential step is the comparison of $\\beta$-strength patterns in $^{11}$Li and the core nucleus $^{9}$Li, another is the full characterization of the break-up processes following the $\\beta$-decay. To enable such a measurement of the full decay process we will use a highly segmented detection system where energy and emission angles of both charged and neutral particles are detected in coincidence and with high efficiency and accuracy. We ask for a total of 30 shifts (21 shifts for $^{11}$Li, 9 shifts $^{9}$Li adding 5 shifts for setting up with stable beam) using a Ta-foil target...

  17. Nuclear structure of light Ca and heavy Cr isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Buerger, A.

    2007-07-01

    -energy Coulomb excitation of radioactive beams. Prior to this experiment, the assumption of a sub-shell closure was based only on systematics of excitation energies of the first 2{sup +} states in Cr, Ti, and Ca isotopes. The small B(E2) value for {sup 56}Cr is in agreement with these indications. Further evidence for a N=32 shell gap has meanwhile been found in the development of B(E2) values in Ti isotopes and the evolution of E(4{sup +})/E(2{sup +}) ratios for Cr and Ti. While the experimental evidence has firmly established a sub-shell closure at N=32, calculations are, at present, not able to reproduce the behavior of the B(E2) values, whereas the evolution of excitation energies is well described. Both results touch the limits of present nuclear structure models: in the Cr isotopes, the B(E2) evolution cannot yet be reproduced, and in the Ca isotopes, a consistent picture of mirror energy differences as well as a successful calculation of cross sections are missing. As a result of this work, new experimental data are available for future improvements of such calculations. (orig.)

  18. Ca isotope fingerprints of early crust-mantle evolution

    Science.gov (United States)

    Kreissig, K.; Elliott, T.

    2005-01-01

    isotope ratios in some mafic samples reflect anomalous K/Ca ratios as a result of intense K-metasomatism ˜3.6 Ga. Thus Ca isotope measurements are not a robust tracer of crustal growth in the presence of intense tectono-metamorphic processes. Coupled with other isotope data, however, the degree of overprint can be estimated and the 40Ca/ 44Ca ratio of a little disturbed sample hints at a small contribution of Hadean protocrust in the coastal part of the Godthåbsfjord area (Southwest Greenland). In the majority of Zimbabwe TTG samples, unradiogenic initial Ca isotope ratios point to very little prior crustal history and minor subsequent disturbance. We thus infer that the modest initial ɛ Nd ˜0.8 of the Zimbabwean samples is representative of the depleted mantle at ˜3.6 Ga. Furthermore, Ca isotope systematics provide little support for a "steady state" model of crustal growth.

  19. Dynamics of the Galapagos hotspot from helium isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, M.D.; Geist, D.

    1999-12-01

    The authors have measured the isotopes of He, Sr, Nd and Pb in a number of lava flows from the Galapagos Archipelago; the main goal is to use magmatic helium as a tracer of plume influence in the western volcanoes. Because the Galapagos lava flows are so well preserved, it is also possible to measure surface exposure ages using in situ cosmic-ray-produced {sup 3}He. The exposure ages range from {lt}0.1 to 580 Ka, are consistent with other chronological constrains, and provide the first direct dating of these lava flows. The new age data demonstrate the utility of the technique in this important age range and show that the western Galapagos volcanoes have been erupting distance compositions simultaneously for the last {approximately}10 Ka. The magmatic {sup 3}He/{sup 4}He ratios range from 6.0 to 27 times atmospheric (R{sub a}), with the highest values found on the islands of Isabella (16.8 R{sub a} for Vulcan Sierra Negra) and Fernandina (23 to 27 R{sub a}). Values from Santa Cruz are close to typical mid-ocean ridge basalt values (MORB, of {approximately}9 R{sub 2}) and Pinta has a {sup 3}He/{sup 4}He ratio lower than MORB (6.9 R{sub a}). These data confirm that the plume is centered beneath Fernandina which is the most active volcano in the archipelago and is at the leading edge of plate motion. The data are consistent with previous isotopic studies, confirming extensive contributions from depleted asthenospheric or lithospheric mantle sources, especially to the central islands. The most striking aspect of the helium isotopic data is that the {sup 3}He/{sup 4}He ratios decrease systematically in all directions from Fernandina. This spatial variability is assumed to reflect the contribution of the purest plume component to Fernandina magmatism, and shows that helium is a sensitive indicator of plume influence. The highest {sup 3}He/{sup 4}He ratios are found in volcanoes with lowest Na{sub 2}O(8) and FeO(8), which may relate to source composition as well as degree

  20. A carbon isotope mass balance for an anoxic marine sediment: Isotopic signatures of diagenesis

    Science.gov (United States)

    Boehme, Susan E.

    1993-01-01

    A carbon isotope mass balance was determined for the sediments of Cape Lookout Bight, NC to constrain the carbon budgets published previously. The diffusive, ebullitive and burial fluxes of sigma CO2 and CH4, as well as the carbon isotope signatures of these fluxes, were measured. The flux-weighted isotopic signature of the remineralized carbon (-18.9 plus or minus 2.7 per mil) agreed with the isotopic composition of the remineralized organic carbon determined from the particulate organic carbon (POC) delta(C-13) profiles (-19.2 plus or minus 0.2), verifying the flux and isotopic signature estimates. The measured delta(C-13) values of the sigma CO2 and CH4 diffusive fluxes were significantly different from those calculated from porewater gradients. The differences appear to be influenced by methane oxidation at the sediment-water interface, although other potential processes cannot be excluded. The isotope mass balance provides important information concerning the locations of potential diagenetic isotope effects. Specifically, the absence of downcore change in the delta(C-13) value of the POC fraction and the identical isotopic composition of the POC and the products of remineralization indicate that no isotopic fractionation is expressed during the initial breakdown of the POC, despite its isotopically heterogeneous composition.

  1. Measurement of isotope abundance variations in nature by gravimetric spiking isotope dilution analysis (GS-IDA).

    Science.gov (United States)

    Chew, Gina; Walczyk, Thomas

    2013-04-02

    Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

  2. Nitrogen isotope fractionation during archaeal ammonia oxidation: Coupled estimates from isotopic measurements of ammonium and nitrite

    Science.gov (United States)

    Mooshammer, Maria; Stieglmeier, Michaela; Bayer, Barbara; Jochum, Lara; Melcher, Michael; Wanek, Wolfgang

    2014-05-01

    Ammonia-oxidizing archaea (AOA) are ubiquitous in marine and terrestrial environments and knowledge about the nitrogen (N) isotope effect associated with their ammonia oxidation activity will allow a better understanding of natural abundance isotope ratios, and therefore N transformation processes, in the environment. Here we examine the kinetic isotope effect for ammonia oxidation in a pure soil AOA culture (Ca. Nitrososphaera viennensis) and a marine AOA enrichment culture. We estimated the isotope effect from both isotopic signatures of ammonium and nitrite over the course of ammonia oxidation. Estimates of the isotope effect based on the change in the isotopic signature of ammonium give valuable insight, because these estimates are not subject to the same concerns (e.g., accumulation of an intermediate) as estimates based on isotopic measurements of nitrite. Our results show that both the pure soil AOA culture and a marine AOA enrichment culture have similar but substantial isotope effect during ammonia consumption (31-34 per mill; based on ammonium) and nitrite production (43-45 per mill; based on nitrite). The 15N fractionation factors of both cultures tested fell in the upper range of the reported isotope effects for archaeal and bacterial ammonia oxidation (10-41 per mill) or were even higher than those. The isotope fractionation for nitrite production was significantly larger than for ammonium consumption, indicating that (1) some intermediate (e.g., hydroxylamine) of ammonia oxidation accumulates, allowing for a second 15N fractionation step to be expressed, (2) a fraction of ammonia oxidized is lost via gaseous N forms (e.g., NO or N2O), which is 15N-enriched or (3) a fraction of ammonium is assimilated into AOA biomass, biomass becoming 15N-enriched. The significance of these mechanisms will be explored in more detail for the soil AOA culture, based on isotope modeling and isotopic measurements of biomass and N2O.

  3. Isotopic geochemistry of Panama rivers

    Science.gov (United States)

    Harmon, Russell S.; Worner, Gerhard; Pribil, Michael; Kern, Zoltan; Forizs, Istvan; Lyons, W. Berry; Gardner, Christopher B.; Goldsmith, Steven T.

    2015-01-01

    River water samples collected from 78 watersheds rivers along a 500-km transect across a Late Cretaceous-Tertiary andesitic volcanic arc terrane in west-central Panama provide a synoptic overview of riverine geochemistry, chemical denudation, and CO2 consumption in the tropics. D/H and 18O/16O relationships indicate that bedrock dissolution of andesitic arc crust in Panama is driven by water-rock interaction with meteoric precipitation as it passes through the critical zone, with no evidence of a geothermal or hydrothermal input. Sr-isotope relationships suggest a geochemical evolution for Panama riverine waters that involves mixing of bedrock pore water with water having 87Sr/86Sr ratios between 0.7037-0.7043 and relatively high Sr-contents with waters of low Sr content that enriched in radiogenic Sr that are diluted by infiltrating rainfall to variable extents.

  4. Sulfur isotopic zoning in apatite crystals: A new record of dynamic sulfur behavior in magmas

    Science.gov (United States)

    Economos, Rita; Boehnke, Patrick; Burgisser, Alain

    2017-10-01

    The mobility and geochemical behavior of sulfur in magmas is complex due to its multi-phase (solid, immiscible liquid, gaseous, dissolved ions) and multi-valent (from S2- to S6+) nature. Sulfur behavior is closely linked with the evolution of oxygen fugacity (fO2) in magmas; the record of fO2 evolution is often enigmatic to extract from rock records, particularly for intrusive systems. We apply a novel method of measuring S isotopic ratios in zoned apatite crystals that we interpret as a record of open-system magmatic processes. We interrogate the S concentration and isotopic variations preserved in multiple apatite crystals from single hand specimens from the Cadiz Valley Batholith, CA via electron microprobe and ion microprobe. Isotopic variations in single apatite crystals ranged from 0 to 3.8‰ δ34S and total variation within a single hand sample was 6.1‰ δ34S. High S concentration cores yielded high isotopic ratios while low S concentration rims yielded low isotopic ratios. We discuss a range of possible natural scenarios and favor an explanation of a combination of magma mixing and open-system, ascent-driven degassing under moderately reduced conditions: fO2 at or below NNO+1, although the synchronous crystallization of apatite and anhydrite is also a viable scenario. Our conclusions have implications for the coupled S and fO2 evolution of granitic plutons and suggest that in-situ apatite S isotopic measurements could be a powerful new tool for evaluating redox and S systematics in magmatic systems.

  5. Studies of control materials of isotope transformation

    Energy Technology Data Exchange (ETDEWEB)

    Noda, Tetsuji; Suzuki, Hiroshi; Araki, Hiroshi; Fujita, Mitsutane; Hirano, Toshiyuki; Abe, Fujio; Numazawa, Takenori [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)

    1999-02-01

    To control wavelength of laser, the physical properties of control materials of molecular excitation and isotope should be studied. We carried out isotopic enrichment, Si thin film growth, and preparation of boron isotope crystal and to make a calculation code of nuclear transmutation simulation. A gas circulation system for developing isotope laser was produced in order to control of molecular vibration excitation. We developed a single straight system of silicon isotope enrichment and silicon thin film preparation by infrared laser. When laser irradiated Si{sub 2}F{sub 6}, unreacted Si{sub 2}F{sub 6} contained 99.72% of {sup 28}Si at about 956 cm{sup -1} wavelength. When SiF{sub 4} or Si{sub 2}F{sub 6} with enriched isotope were directly decomposed by the plasma CVD method at about from 350 to 450degC, the yield of silicon crystal was about 28%. A homogeneous crystal with 10 mm diameter was obtained as the control material of boron isotope. The computer code for simulation of nuclear transmutation was improved to calculate the displacement damage, change of composition, induced radioactivity and decay heat. (S.Y.)

  6. Si isotope homogeneity of the solar nebula

    Energy Technology Data Exchange (ETDEWEB)

    Pringle, Emily A.; Savage, Paul S.; Moynier, Frédéric [Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130 (United States); Jackson, Matthew G. [Department of Earth Science, University of California, Santa Barbara, CA 93109 (United States); Barrat, Jean-Alix, E-mail: eapringle@wustl.edu, E-mail: savage@levee.wustl.edu, E-mail: pringle@ipgp.fr, E-mail: moynier@ipgp.fr, E-mail: jackson@geol.ucsb.edu, E-mail: Jean-Alix.Barrat@univ-brest.fr [Université Européenne de Bretagne, Université de Brest, CNRS UMR 6538 (Domaines Océaniques), I.U.E.M., Place Nicolas Copernic, F-29280 Plouzané Cedex (France)

    2013-12-20

    The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in {sup 29}Si/{sup 28}Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of {sup 29}Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the calcium-aluminum-rich inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

  7. Seafloor alteration, oxygen isotopes and climate

    Science.gov (United States)

    Kanzaki, Y.; Kump, L. R.; Kasting, J. F.

    2016-12-01

    Seafloor alteration can be related to climate in two ways: through storage of carbon dioxide as carbonates and indirectly through its influence on the oxygen isotopic composition of seawater. Low temperature alteration of the seafloor, or seafloor weathering, can store carbon dioxide as carbonates formed as the result of dissolution of cations from silicate rocks, and since this process is temperature dependent, can serve as a climate regulator. On the other hand, the oxygen isotopic composition of seawater is determined by the balance between low temperature crustal alteration (including continental weathering) and high temperature seafloor alteration, because the heavy isotope is depleted from and added to seawater in low and high temperature alteration, respectively. The oxygen isotopic composition of seawater is a parameter necessary to estimate surface temperature of the Earth from the oxygen isotopic composition of authigenic sedimentary rocks. Thus seafloor alteration is related to reconstruction of Earth's climate. We have developed a comprehensive model of seafloor alteration that captures both seafloor weathering and oxygen isotope exchange, and use it to reconcile observations of long-term stability in both climate and altered ocean crust δ18O with secular changes in the oxygen isotopic composition of marine sediments.

  8. Fe-isotope fractionation during partial melting on Earth and the current view on the Fe-isotope budgets of the planets (reply to the comment of F. Poitrasson and to the comment of B.L. Beard and C.M. Johnson on “Iron isotope fractionation during planetary differentiation” by S. Weyer, A.D. Anbar, G.P. Brey, C. Münker, K. Mezger and A.B. Woodland)

    Science.gov (United States)

    Weyer, S.; Anbar, A. D.; Brey, G. P.; Münker, C.; Mezger, K.; Woodland, A. B.

    2007-04-01

    In their comments on our recent paper [S. Weyer, A.D. Anbar, G.P. Brey, C. Müncker, K. Mezger, A.B. Woodland, Iron isotope fractionation during planetary differentiation. Earth Planet. Sci. Lett. 240 (2005) 251-264], Poitrasson [F. Poitrasson, Does planetary differentiation really fractionate iron isotopes? A comment on "Iron isotope fractionation during planetary differentiation" by S. Weyer, A.D. Anbar, G.P. Brey, C. Münker, K. Mezger, A.B. Woodland, EPSL, vol. 240: 251-264., Earth Planet. Sci. Lett. this issue (2007)] and Beard and Johnson [B.L. Beard, C.M. Johnson, Comment on "Iron isotope fractionation during planetary differentiation" by S. Weyer et al., Earth Planet. Sci. Letts. V240, pages 251-264., Earth Planet. Sci. Lett. this issue (2007)] argued that there is currently no evidence that the Fe-isotope composition fractionates during silicate differentiation on planets. Based on the investigation of crustal materials they claim that differences in the Fe-isotope compositions of planets can be best explained by their different accretion histories. However, based on a compilation of Fe-isotope analyses from recent studies, we show that there is increasing evidence for a systematically lighter Fe-isotope composition of the terrestrial upper mantle compared to basalts, and that Fe-isotope fractionation during partial melting is the most likely process responsible for this isotopic difference. Additionally, we show that the average value and also the observed range of Fe-isotope compositions of basalts and other differentiated rocks from the Earth and the Moon are very similar. Thus, there is currently little evidence that the Moon is isotopically heavier than the Earth, as earlier proposed by Poitrasson et al. [F. Poitrasson, A. Halliday, D. Lee, S. Levasseur, N. Teutsch, Iron isotope differences between Earth, Moon, Mars and Vesta as possible records of contrasted accretion mechanisms. Earth Planet. Sci. Lett. 223 (2004) 253-266]. However, most likely the

  9. Isotopic tracing of perchlorate in the environment

    Science.gov (United States)

    Sturchio, Neil C.; Böhlke, John Karl; Gu, Baohua; Hatzinger, Paul B.; Jackson, W. Andrew; Baskaran, Mark

    2012-01-01

    Isotopic measurements can be used for tracing the sources and behavior of environmental contaminants. Perchlorate (ClO 4 − ) has been detected widely in groundwater, soils, fertilizers, plants, milk, and human urine since 1997, when improved analytical methods for analyzing ClO 4 −concentration became available for routine use. Perchlorate ingestion poses a risk to human health because of its interference with thyroidal hormone production. Consequently, methods for isotopic analysis of ClO 4 − have been developed and applied to assist evaluation of the origin and migration of this common contaminant. Isotopic data are now available for stable isotopes of oxygen and chlorine, as well as 36Cl isotopic abundances, in ClO 4 − samples from a variety of natural and synthetic sources. These isotopic data provide a basis for distinguishing sources of ClO 4 − found in the environment, and for understanding the origin of natural ClO 4 − . In addition, the isotope effects of microbial ClO 4 − reduction have been measured in laboratory and field experiments, providing a tool for assessing ClO 4 − attenuation in the environment. Isotopic data have been used successfully in some areas for identifying major sources of ClO 4 − contamination in drinking water supplies. Questions about the origin and global biogeochemical cycle of natural ClO 4 − remain to be addressed; such work would benefit from the development of methods for preparation and isotopic analysis of ClO 4 − in samples with low concentrations and complex matrices.

  10. Intramolecular Isotopic Studies: Chemical Enhancements and Alternatives

    Science.gov (United States)

    Hayes, J. M.

    2016-12-01

    As mass spectroscopic and NMR-based methods now appropriately flourish, chemical techniques should not be forgotten. First, the methods developed by pioneering intramolecular analysts can be reapplied to new samples. Second, they can be extended. The synthesis of intramolecular isotopic standards is particularly important and straightforward. It requires only that a chemical reaction has no secondary products. An example is provided by the addition of carbon dioxide to a Grignard reagent. The reaction proceeds with an isotope effect. The isotopic composition of the carboxyl group in the acid which is produced is thus not equal to that of the starting carbon dioxide but the unconsumed CO2 can be recovered and analyzed. A simple titration can show that all the rest of the CO2 is in the product acid. The isotopic composition of the carboxyl group can then be calculated by difference. The product is an intramolecular isotopic standard, an organic molecule in which the isotopic composition of a specific carbon position is known accurately. Both analysts and reviewers can thus gain invaluable confidence in the accuracy of instrumental results. A second example: the haloform reaction quantitatively degrades methyl ketones, producing a carboxylic acid which can be decarboxylated to determine the isotopic composition of the parent carbonyl and a haloform (CHI3, for example) that can be combusted to determine the isotopic composition of the methyl group. Ketones thus analyzed can be combined with Grignard reagents to yield carbon skeletons in which the isotopic compositions of internal and terminal -CH2- and -CH3 groups are known accurately. In general, analysts accustomed to demanding quantitative reactions should remember the power of mass balances and recognize that many organic-chemical reactions, while not quantitative, lack side products and can be driven to the total consumption of at least one reactant.

  11. Heavy Stable Isotopes: From Exceptional to Expected

    Science.gov (United States)

    Anbar, A.

    2006-12-01

    Less than a decade ago, the stable isotope geochemistry of transition metals and other "heavy" elements was a highly specialized niche confined to a few seemingly exceptional elements. This situation was transformed by the development and refinement of MC-ICP-MS techniques, particularly in the last five years. Measurable stable isotope variations turn out to be ubiquitous across the periodic table, from Li to Hg. It is now safe to assume that the isotopic composition of any element with two or more stable isotopes is measurably variable. What was once exceptional is now expected. Among the first of these new systems to be explored were Fe and Mo isotopes. A number of lessons emerging from this work can be applied to the development of other isotope systems. Most important is that initial expectations are often wrong. For example, based on their environmental chemistries it was expected that redox reactions should produce some of the largest isotope effects for both elements. In the case of Fe, theoretical and experimental studies converge to convincingly indicate that a fractionation of ~ 1.5 ‰/amu occurs between Fe(III) and Fe(II) aquo complexes at equilibrium (e.g., Welch et al., 2003; Anbar et al., 2005). Consistent with these findings, most natural variations of are < 1.5 ‰/amu (e.g., Johnson et al., 2004). This redox-related fractionation is at the heart of emerging interpretations of variations in the isotopic composition of Fe and their application to understanding ancient ocean redox (e.g., Dauphas et al., 2004; Rouxel et al., 2005). In contrast, Mo isotope variations turn out to be controlled only indirectly by redox conditions. Instead, one of the most important Mo isotope effects in the environment appears to be a fractionation of ~ 1 ‰/amu during adsorption of Mo to Mn-oxides (Barling et al., 2001; Siebert et al., 2003). This fractionation has been reproduced in the laboratory (Barling and Anbar, 2004) and appears to be an equilibrium isotope

  12. Hafnium isotope stratigraphy of ferromanganese crusts

    Science.gov (United States)

    Lee, D.-C.; Halliday, A.N.; Hein, J.R.; Burton, K.W.; Christensen, J.N.; Gunther, D.

    1999-01-01

    A Cenozoic record of hafnium isotopic compositions of central Pacific deep water has been obtained from two ferromanganese crusts. The crusts are separated by more than 3000 kilometers but display similar secular variations. Significant fluctuations in hafnium isotopic composition occurred in the Eocene and Oligocene, possibly related to direct advection from the Indian and Atlantic oceans. Hafnium isotopic compositions have remained approximately uniform for the past 20 million years, probably reflecting increased isolation of the central Pacific. The mechanisms responsible for the increase in 87Sr/86Sr in seawater through the Cenozoic apparently had no effect on central Pacific deep-water hafnium.

  13. The Facility for Rare Isotope Beams

    Directory of Open Access Journals (Sweden)

    Wrede C.

    2015-01-01

    Full Text Available The Facility for Rare Isotope Beams (FRIB is a United States Department of Energy user facility currently under construction on the campus of Michigan State University. Based on a 400 kW, 200 MeV/u heavy-ion driver linac, FRIB will deliver high-quality fast, thermalized, and re-accelerated beams of rare isotopes with unprecedented intensities to a variety of experimental areas and equipment. New science opportunities at the frontiers of nuclear structure, nuclear astrophysics, fundamental symmetries, and societal applications will be enabled by this future world-leading rare-isotope beam facility.

  14. The Facility for Rare Isotope Beams

    Science.gov (United States)

    Wrede, C.

    2015-05-01

    The Facility for Rare Isotope Beams (FRIB) is a United States Department of Energy user facility currently under construction on the campus of Michigan State University. Based on a 400 kW, 200 MeV/u heavy-ion driver linac, FRIB will deliver high-quality fast, thermalized, and re-accelerated beams of rare isotopes with unprecedented intensities to a variety of experimental areas and equipment. New science opportunities at the frontiers of nuclear structure, nuclear astrophysics, fundamental symmetries, and societal applications will be enabled by this future world-leading rare-isotope beam facility.

  15. Titanium Isotopes Provide Clues to Lunar Origin

    Science.gov (United States)

    Taylor, G. J.

    2012-05-01

    The idea that the Moon formed as the result of the giant impact of a Mars-sized impactor with the still-growing Earth explains two central facts about the Earth-Moon system: its total angular momentum (Earth's spin and the Moon's orbital motion), and the sizes of the metallic cores of the Earth (large) and Moon (tiny). This gives cosmochemists some confidence in the hypothesis, but they would greatly appreciate additional compositional tests. One undisputed point is the identical abundance of the three oxygen isotopes in Earth and Moon. Junjun Zhang and colleagues at the University of Chicago (USA) and the University of Bern (Switzerland) have added another isotopic system to the cosmochemical testing tool kit, titanium isotopes. They find that the ratio of titanium-50 to titanium-47 is identical in Earth and Moon to within four parts per million. In contrast, other solar system materials, such as carbonaceous chondrites, vary by considerably more than this-- up to 150 times as much. The identical oxygen and titanium isotopic compositions in Earth and Moon are surprising in light of what we think we know about planet formation and formation of the Moon after a giant impact. The variations in oxygen and titanium isotopes among meteorite types suggest that it is unlikely that the Moon-forming giant impactor would have had the same isotopic composition as the Earth. Simulations show that the Moon ends up constructed mostly (40-75%) from the impactor materials. Thus, the Moon ought to have different isotopic composition than does Earth. The isotopes might have exchanged in the complicated, messy proto-lunar disk (as has been suggested for oxygen isotopes), making them the same. However, Zhang and colleagues suggest that this exchange is unlikely for a refractory element like titanium. Could the impact simulations be greatly overestimating the contributions from the impactor? Was the mixing of building-block materials throughout the inner solar system much less than

  16. Beneficial uses and production of isotopes

    CERN Document Server

    2001-01-01

    Isotopes, radioactive and stable, are used worldwide in various applications related to medical diagnosis or care, industry and scientific research. More than fifty countries have isotope production or separation facilities operated for domestic supply, and sometimes for international markets. This publication provides up-to-date information on the current status of, and trends in, isotope uses and production. It also presents key issues, conclusions and recommendations, which will be of interest to policy makers in governmental bodies, scientists and industrial actors in the field.

  17. Hafnium isotope stratigraphy of ferromanganese crusts

    Science.gov (United States)

    Lee; Halliday; Hein; Burton; Christensen; Gunther

    1999-08-13

    A Cenozoic record of hafnium isotopic compositions of central Pacific deep water has been obtained from two ferromanganese crusts. The crusts are separated by more than 3000 kilometers but display similar secular variations. Significant fluctuations in hafnium isotopic composition occurred in the Eocene and Oligocene, possibly related to direct advection from the Indian and Atlantic oceans. Hafnium isotopic compositions have remained approximately uniform for the past 20 million years, probably reflecting increased isolation of the central Pacific. The mechanisms responsible for the increase in (87)Sr/(86)Sr in seawater through the Cenozoic apparently had no effect on central Pacific deep-water hafnium.

  18. Systematic reviews in context: highlighting systematic reviews ...

    African Journals Online (AJOL)

    For example, in the 18th century James Lind conducted a clinical trial followed by a systematic review of contemporary treatments for scurvy; which showed fruits to be an effective treatment for the disease. However, surveys of the peerreviewed literature continue to provide empirical evidence that systematic reviews are ...

  19. New Isotopic Tracers for Shale Gas and Hydraulic Fracturing Fluids

    Science.gov (United States)

    The combined application of geochemistry, stable isotopes (δ18O, δ2H), strontium isotopes (87Sr/86Sr), boron isotopes (δ11B), and radium isotopes (228Ra/226Ra) provides a unique methodology for tracing and monitoring shale gas and fracking fluids in the environment.

  20. A microscopic study of deformation systematics in 154−166Dy ...

    Indian Academy of Sciences (India)

    A microscopic study of deformation systematics in 154−166Dy isotopes. AMITA DUA, ARUN BHARTI. ∗ and S K KHOSA. Department of Physics, University of Jammu, Jammu & Kashmir 180 006, India. ∗. Corresponding Author. E-mail: arunbharti 2003@yahoo.co.in. MS received 30 March 2006; revised 9 March 2007; ...

  1. Quasi-free Proton Knockout Reactions on the Oxygen Isotopic Chain

    Science.gov (United States)

    Atar, Leyla; Aumann, Thomas; Bertulani, Carlos; Paschalis, Stefanos; R3B Collaboration

    2017-09-01

    It is well known from electron-induced knockout data that the single-particle (SP) strength is reduced to about 60-70% for stable nuclei in comparison to the independent particle model due to the presence of short- and long-range correlations. This finding has been confirmed by nuclear knockout reactions using stable and exotic beams, however, with a strong dependency on the proton-neutron asymmetry. The observed strong reduction of SP cross sections for the deeply bound valence nucleons in asymmetric nuclei is theoretically not understood. To understand this dependency quantitatively a complementary approach, quasi-free (QF) knockout reactions in inverse kinematics, is introduced. We have performed a systematic study of spectroscopic strength of oxygen isotopes using QF (p,2p) knockout reactions in complete kinematics at the R3B/LAND setup at GSI with secondary beams containing 13-24O. The oxygen isotopic chain covers a large variation of separ ation energies, which allow a systematic study of SF with respect to isospin asymmetry. We will present results on the (p,2p) cross sections for the entire oxygen isotopic chain obtained from a single experiment. By comparison with the Eikonal reaction theory the SF and reduction factors will be presented. The work is supported by GSI-TU Darmstadt cooperation and BMBF project 05P15RDFN1.

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

    Energy Technology Data Exchange (ETDEWEB)

    Miller, P.

    1998-01-05

    This short course includes information on these topics and subtopics: (I) Nuclear Properties: (A) Historic roots; (B) Nomenclature; (C) Nuclear Stability and abundance; (D) Uses of isotopic techniques; (II) Instrumentation: (A) Sources; (B) Mass resolving elements; (C) Detectors; (III) Making Isotopic Measurements by ICP-MS: (A) Deadtime Correction; (B) Mass Discrimination; (C) Signal /Noise considerations; (IV) Applications and examples: (A) Isotope dilution; (B) Double Spike; (C) Biological Application; (D) Environmental Application; (E) Geological.

  3. Alpha decay of neutron-deficient isotopes with 52isotopes /sup 106/Te (T/sub 1/2/=60 mu s) and /sup 110/Xe

    CERN Document Server

    Schardt, D; Kirchner, R; Klepper, O; Kurcewicz, W; Roeckl, E; Tidemand-Petersson, P

    1981-01-01

    Using /sup 58/Ni(/sup 58/Ni, xpyn) reactions and on-line mass separation, the alpha -decays of very neutron-deficient isotopes of tellurium, iodine, xenon and cesium were studied. The new isotopes /sup 106/Te (T/sub 1/2/=60/sub -10//sup +30/ mu s) and /sup 110/Xe were identified by their alpha -lines of 4160+or-30 keV and 3737+or-30 keV energy, respectively, with the genetic relationship between the two successive alpha -decays being verified experimentally, while for several other alpha -decaying isotopes more precise data were obtained. The observed alpha -decay properties are discussed within the systematics of energy and reduced width. (19 refs).

  4. Fingerprints of environmental stressors in three selected Slovenian gravel-bed rivers: geochemical and isotopic approach

    Science.gov (United States)

    Kanduč, Tjaša; Kocman, David; Debeljak, Barbara; Mori, Nataša

    2016-04-01

    Rivers are severely impacted by a range of simultaneous processes including water pollution, flow and channel alteration, over-fishing, invasive species and climate change. Systematic studies of river water geochemistry provide important information on chemical weathering of bedrock/soil and natural anthropogenic processes that may control the dissolved chemical loads, while the isotopic studies of biological components of river systems (macrophytes, periphyton, heterotrophic biofilm, invertebrates, fish) contribute to the understanding how the system response to human impacts by means of functional response. In this contribution, insights in the fingerprints of various environmental stressors in three gravel-bed rivers (River Kamni\\vska Bistrica, River Idrijca and River Sava) in Slovenia, using geochemical and stable isotope approach are discussed. Gravel bed of all three rivers investigated is composed of carbonates and clastic rocks. The Sava and Kamni\\vska Bistrica Rivers have alpine high mountain snow-rain regime. The Idrijca River is a boundary river between the Adriatic and Black Sea catchments and has rain-snow discharge regime with torrential character. Geochemical methods (ICP-OES, IC, total alkalinity after Gran) and isotope mass - spectrometric methods (isotopic composition of dissolved inorganic carbon, particulate organic carbon and isotopic composition of carbon in carbonates) were used to evaluate biogeochemical processes in rivers. Isotopic composition of carbon and nitrogen of the moss Fontinalis antipyretica (the whole vegetative shoot) and isotopic composition of carbon of heterotrophic biofilm was also analyzed in order to better understand the fluxes and fractionation of carbon and nitrogen across trophic levels. Geochemical composition of all investigated rivers is HCO3--Ca2+-Mg2+ with different Mg2+/Ca2+ ratios as follows: around 0.33 for Kamni\\vska Bistrica and River Sava in Slovenia and above 0.75 for River Idrijca. In the Kamni

  5. Influence of liquid structure on diffusive isotope separation in molten silicates and aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, J.M.; DePaolo, D.J.; Ryerson, F.J.; Peterson, B.

    2011-03-01

    Molecular diffusion in natural volcanic liquids discriminates between isotopes of major ions (e.g., Fe, Mg, Ca, and Li). Although isotope separation by diffusion is expected on theoretical grounds, the dependence on mass is highly variable for different elements and in different media. Silicate liquid diffusion experiments using simple liquid compositions were carried out to further probe the compositional dependence of diffusive isotopic discrimination and its relationship to liquid structure. Two diffusion couples consisting of the mineral constituents anorthite (CaAl{sub 2}Si{sub 2}O{sub 8}; denoted AN), albite (NaAlSi{sub 3}O{sub 8}; denoted AB), and diopside (CaMgSi{sub 2}O{sub 6}; denoted DI) were held at 1450°C for 2 h and then quenched to ambient pressure and temperature. Major-element as well as Ca and Mg isotope profiles were measured on the recovered quenched glasses. In both experiments, Ca diffuses rapidly with respect to Si. In the AB–AN experiment, D{sub Ca}/D{sub Si} ~ 20 and the efficiency of isotope separation for Ca is much greater than in natural liquid experiments where D{sub Ca}/D{sub Si} ~ 1. In the AB–DI experiment, D{sub Ca}/D{sub Si} ~ 6 and the efficiency of isotope separation is between that of the natural liquid experiments and the AB–AN experiment. In the AB–DI experiment, D{sub Mg}/D{sub Si} ~ 1 and the efficiency of isotope separation for Mg is smaller than it is for Ca yet similar to that observed for Mg in natural liquids. The results from the experiments reported here, in combination with results from natural volcanic liquids, show clearly that the efficiency of diffusive separation of Ca isotopes is systematically related to the solvent-normalized diffusivity—the ratio of the diffusivity of the cation (D{sub Ca}) to the diffusivity of silicon (D{sub Si}). The results on Ca isotopes are consistent with available data on Fe, Li, and Mg isotopes in silicate liquids, when considered in terms of the parameter D{sub cation

  6. Copper and iron isotope fractionation during weathering and pedogenesis: Insights from saprolite profiles

    Science.gov (United States)

    Liu, Sheng-Ao; Teng, Fang-Zhen; Li, Shuguang; Wei, Gang-Jian; Ma, Jing-Long; Li, Dandan

    2014-12-01

    Iron and copper isotopes are useful tools to track redox transformation and biogeochemical cycling in natural environment. To study the relationships of stable Fe and Cu isotopic variations with redox regime and biological processes during weathering and pedogenesis, we carried out Fe and Cu isotope analyses for two sets of basalt weathering profiles (South Carolina, USA and Hainan Island, China), which formed under different climatic conditions (subtropical vs. tropical). Unaltered parent rocks from both profiles have uniform δ56Fe and δ65Cu values close to the average of global basalts. In the South Carolina profile, δ56Fe values of saprolites vary from -0.01‰ to 0.92‰ in the lower (reduced) part and positively correlate with Fe3+/ΣFe (R2 = 0.90), whereas δ65Cu values are almost constant. By contrast, δ56Fe values are less variable and negatively correlate with Fe3+/ΣFe (R2 = 0.88) in the upper (oxidized) part, where large (4.85‰) δ65Cu variation is observed with most samples enriched in heavy isotopes. In the Hainan profile formed by extreme weathering under oxidized condition, δ56Fe values vary little (0.05-0.14‰), whereas δ65Cu values successively decrease from 0.32‰ to -0.12‰ with depth below 3 m and increase from -0.17‰ to 0.02‰ with depth above 3 m. Throughout the whole profile, δ65Cu positively correlate with Cu concentration and negatively correlate with the content of total organic carbon (TOC). Overall, the contrasting Fe isotopic patterns under different redox conditions suggest redox states play the key controls on Fe mobility and isotope fractionation. The negative correlation between δ56Fe and Fe3+/ΣFe in the oxidized part of the South Carolina profile may reflect addition of isotopically light Fe. This is demonstrated by leaching experiments, which show that Fe mineral pools extracted by 0.5 N HCl, representing poorly-crystalline Fe (hydr)-oxides, are enriched in light Fe isotopes. The systematic Cu isotopic variation

  7. Strontium isotope geochemistry of alluvial groundwater: a tracer for groundwater resources characterisation

    Directory of Open Access Journals (Sweden)

    P. Négrel

    2004-01-01

    Full Text Available This study presents strontium isotope and major ion data of shallow groundwater and river water from the Ile du Chambon catchment, located on the Allier river in the Massif Central (France. There are large variations in the major-element contents in the surface- and groundwater. Plotting of Na vs. Cl contents and Ca, Mg, NO3, K, SO4, HCO3, Sr concentrations reflect water–rock interaction (carbonate dissolution for Ca, Mg, HCO3 and Sr because the bedrock contains marly limestones, agricultural input (farming and fertilising and sewage effluents (for NO3, K, SO4, although some water samples are unpolluted. Sr contents and isotope ratios (87Sr/86Sr vary from 0.70892 to 0.71180 along the hydrological cycle in the groundwater agree with previous work on groundwater in alluvial aquifers in the Loire catchment. The data plot along three directions in a 87Sr/86Sr v. 1/Sr diagram as a result of mixing, involving at least three geochemical signatures–Allier river water, and two distinct signatures that might be related to different water-rock interactions in the catchment. Mixing proportions are calculated and discussed. The alluvial aquifer of the Ile du Chambon catchment is considered, within the Sr isotope systematic, in a larger scheme that includes several alluvial aquifers of the Loire Allier catchment. Keywords: : Loire river, major and trace elements, Sr isotopic ratio, alluvial aquifer, hydrology

  8. Dietary resilience among hunter-gatherers of Tierra del Fuego: Isotopic evidence in a diachronic perspective.

    Science.gov (United States)

    Tafuri, Mary Anne; Zangrando, Atilio Francisco Javier; Tessone, Augusto; Kochi, Sayuri; Moggi Cecchi, Jacopo; Di Vincenzo, Fabio; Profico, Antonio; Manzi, Giorgio

    2017-01-01

    The native groups of Patagonia have relied on a hunter-gatherer economy well after the first Europeans and North Americans reached this part of the world. The large exploitation of marine mammals (i.e., seals) by such allochthonous groups has had a strong impact on the local ecology in a way that might have forced the natives to adjust their subsistence strategies. Similarly, the introduction of new foods might have changed local diet. These are the premises of our isotopic-based analysis. There is a large set of paleonutritional investigations through isotopic analysis on Fuegians groups, however a systematic exploration of food practices across time in relation to possible pre- and post-contact changes is still lacking. In this paper we investigate dietary variation in hunter-gatherer groups of Tierra del Fuego in a diachronic perspective, through measuring the isotopic ratio of carbon (∂13C) and nitrogen (∂15N) in the bone collagen of human and a selection of terrestrial and marine animal samples. The data obtained reveal an unexpected isotopic uniformity across prehistoric and recent groups, with little variation in both carbon and nitrogen mean values, which we interpret as the possible evidence of resilience among these groups and persistence of subsistence strategies, allowing inferences on the dramatic contraction (and extinction) of Fuegian populations.

  9. The systematization of practice

    DEFF Research Database (Denmark)

    Vidal, Rene Victor Valqui

    2002-01-01

    this paper presents an approach for the systematization of practical experiences whitin Operations Research, Community work, Systems Sciences, Action Research, etc. A case study is presented: the systematization of the activities of a development center in Denmark.......this paper presents an approach for the systematization of practical experiences whitin Operations Research, Community work, Systems Sciences, Action Research, etc. A case study is presented: the systematization of the activities of a development center in Denmark....

  10. Evaluating chlorine isotope effects from isotope ratios and mass spectra of polychlorinated molecules.

    Science.gov (United States)

    Elsner, Martin; Hunkeler, Daniel

    2008-06-15

    Compound-specific chlorine isotope analysis receives much interest to assess the fate of chlorinated hydrocarbons in contaminated environments. This paper provides a theoretical basis to calculate isotope ratios and quantify isotope fractionation from ion-current ratios of molecular- and fragment-ion multiplets. Because both (35)Cl and (37)Cl are of high abundance, polychlorinated hydrocarbons consist of molecules containing different numbers of (37)Cl denoted as isotopologues. We show that, during reactions, the changes in isotopologue ratios are proportional to changes in the isotope ratio assuming a nonselective isotope distribution in the initial compound. This proportionality extents even to fragments formed in the ion source of a mass spectrometer such as C 2Cl 2 (double dechlorinated fragment of perchloroethylene, PCE). Fractionation factors and kinetic isotope effects (KIE) may, therefore, be evaluated from isotope, isotopologue or even fragment ratios according to conventional simple equations. The proportionality is exact with symmetric molecules such as dichloroethylene (DCE) and PCE, whereas it is approximately true with molecules containing nonreactive positions such as trichloroethylene (TCE). If in the latter case isotope ratios are derived from dechlorinated fragments, e.g., C 2HCl 2, it is important that fragmentation in the ion source affect all molecular positions alike, as otherwise isotopic changes in reactive positions may be underrepresented.

  11. Quantification of isotopic turnover in agricultural systems

    Science.gov (United States)

    Braun, A.; Auerswald, K.; Schnyder, H.

    2012-04-01

    The isotopic turnover, which is a proxy for the metabolic rate, is gaining scientific importance. It is quantified for an increasing range of organisms, from microorganisms over plants to animals including agricultural livestock. Additionally, the isotopic turnover is analyzed on different scales, from organs to organisms to ecosystems and even to the biosphere. In particular, the quantification of the isotopic turnover of specific tissues within the same organism, e.g. organs like liver and muscle and products like milk and faeces, has brought new insights to improve understanding of nutrient cycles and fluxes, respectively. Thus, the knowledge of isotopic turnover is important in many areas, including physiology, e.g. milk synthesis, ecology, e.g. soil retention time of water, and medical science, e.g. cancer diagnosis. So far, the isotopic turnover is quantified by applying time, cost and expertise intensive tracer experiments. Usually, this comprises two isotopic equilibration periods. A first equilibration period with a constant isotopic input signal is followed by a second equilibration period with a distinct constant isotopic input signal. This yields a smooth signal change from the first to the second signal in the object under consideration. This approach reveals at least three major problems. (i) The input signals must be controlled isotopically, which is almost impossible in many realistic cases like free ranging animals. (ii) Both equilibration periods may be very long, especially when the turnover rate of the object under consideration is very slow, which aggravates the first problem. (iii) The detection of small or slow pools is improved by large isotopic signal changes, but large isotopic changes also involve a considerable change in the input material; e.g. animal studies are usually carried out as diet-switch experiments, where the diet is switched between C3 and C4 plants, since C3 and C4 plants differ strongly in their isotopic signal. The

  12. The Most Useful Actinide Isotope: Americium-241.

    Science.gov (United States)

    Navratil, James D.; And Others

    1990-01-01

    Reviewed is the discovery, nuclear and chemical properties, and uses of an isotope of Americium (Am-241). Production and separation techniques used in industry are emphasized. Processes are illustrated in flow sheets. (CW)

  13. Barium Isotopes in Single Presolar Grains

    Science.gov (United States)

    Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2001-01-01

    Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

  14. The production of stable isotopes in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Urgel, M.; Iglesias, J.; Casas, J.; Saviron, J. M.; Quintanilla, M.

    1965-07-01

    The activities developed in the field of the production of stable isotopes by means of ion-exchange chromatography and thermal diffusion techniques are reported. The first method was used to study the separation of the nitrogen and boron isotopes, whereby the separation factor was determined by the break through method. Values ranging from 1,028 to 1,022 were obtained for the separation factor of nitrogen by using ammonium hydroxide solutions while the corresponding values as obtained for boron amounted to 1,035-1,027 using boric acid solutions. Using ammonium chloride or acetate and sodium borate, respectively, resulted in the obtention of values for the separation factor approaching unity. The isotopic separation has been carried out according to the method of development by displacement. The separation of the isotopes of the noble gases, oxygen, nitrogen and carbon has been accomplished resorting to the method of thermal diffusion. (Author) 16 refs.

  15. Robust optical carbon dioxide isotope analyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Isotopic analysis of carbon dioxide is an important tool for characterization of the exchange and transformation of carbon between the biosphere and the atmosphere....

  16. Benchmarking stable isotope labeling based quantitative proteomics

    NARCIS (Netherlands)

    Altelaar, A.F.M.|info:eu-repo/dai/nl/304833517; Frese, C.K.; Preisinger, C.|info:eu-repo/dai/nl/325801703; Hennrich, M.L.|info:eu-repo/dai/nl/314406778; Schram, A.W.; Timmers, H.T.M.; Heck, A.J.R.|info:eu-repo/dai/nl/105189332; Mohammed, S.|info:eu-repo/dai/nl/30483632X

    Several quantitative mass spectrometry based technologies have recently evolved to interrogate the complexity, interconnectivity and dynamic nature of proteomes. Currently, the most popular methods use either metabolic or chemical isotope labeling with MS based quantification or chemical labeling

  17. Allan Hills Stable Water Isotopes, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes stable water isotope values at 10 m resolution along an approximately 5 km transect through the main icefield of the Allan Hills Blue Ice...

  18. The magnesium isotope (δ26Mg) signature of dolomites

    Science.gov (United States)

    Geske, A.; Goldstein, R. H.; Mavromatis, V.; Richter, D. K.; Buhl, D.; Kluge, T.; John, C. M.; Immenhauser, A.

    2015-01-01

    Dolomite precipitation models and kinetics are debated and complicated due to the complex and temporally fluctuating fluid chemistry and different diagenetic environments. Using well-established isotope systems (δ18O, δ13C, 87Sr/86Sr), fluid inclusions and elemental data, as well as a detailed sedimentological and petrographic data set, we established the precipitation environment and subsequent diagenetic pathways of a series of Proterozoic to Pleistocene syn-depositional marine evaporative (sabkha) dolomites, syn-depositional non-marine evaporative (lacustrine and palustrine) dolomites, altered marine ("mixing zone") dolomites and late diagenetic hydrothermal dolomites. These data form the prerequisite for a systematic investigation of dolomite magnesium isotope ratios (δ26Mgdol). Dolomite δ26Mg ratios documented here range, from -2.49‰ to -0.45‰ (δ26Mgmean = -1.75 ± 1.08‰, n = 42). The isotopically most depleted end member is represented by earliest diagenetic marine evaporative sabkha dolomites (-2.11 ± 0.54‰ 2σ, n = 14). In comparing ancient compositions to modern ones, some of the variation is probably due to alteration. Altered marine (-1.41 ± 0.64‰ 2σ, n = 4), and earliest diagenetic lacustrine and palustrine dolomites (-1.25 ± 0.86‰ 2σ, n = 14) are less negative than sabkha dolomites but not distinct in composition. Various hydrothermal dolomites are characterized by a comparatively wide range of δ26Mg ratios, with values of -1.44 ± 1.33‰ (2σ, n = 10). By using fluid inclusion data and clumped isotope thermometry (Δ47) to represent temperature of precipitation for hydrothermal dolomites, there is no correlation between fluid temperature (∼100 to 180 °C) and dolomite Mg isotope signature (R2 = 0.14); nor is there a correlation between δ26Mgdol and δ18Odol. Magnesium-isotope values of different dolomite types are affected by a complex array of different Mg sources and sinks, dissolution/precipitation and non

  19. Sulfur Isotope Effects of Dissimilatory Sulfite Reductase

    Directory of Open Access Journals (Sweden)

    William D. Leavitt

    2015-12-01

    Full Text Available The precise interpretation of environmental sulfur isotope records requires a quantitative understanding of the biochemical controls on sulfur isotope fractionation by the principle isotope-fractionating process within the S cycle, microbial sulfate reduction (MSR. Here we provide the only direct observation of the major (34S/32S and minor (33S/32S, 36S/32S sulfur isotope fractionations imparted by a central enzyme in the energy metabolism of sulfate reducers, dissimilatory sulfite reductase (DsrAB. Results from in vitro sulfite reduction experiments allow us to calculate the in vitro DsrAB isotope effect in 34S/32S (hereafter, 34εDsrAB to be 15.3±2‰, 2σ. The accompanying minor isotope effect in 33S, described as 33λDsrAB, is calculated to be 0.5150±0.0012, 2σ. These observations facilitate a rigorous evaluation of the isotopic fractionation associated with the dissimilatory MSR pathway, as well as of the environmental variables that govern the overall magnitude of fractionation by natural communities of sulfate reducers. The isotope effect induced by DsrAB upon sulfite reduction is a factor of 0.3 to 0.6 times prior indirect estimates, which have ranged from 25 to 53‰ in 34εDsrAB. The minor isotope fractionation observed from DsrAB is consistent with a kinetic or equilibrium effect. Our in vitro constraints on the magnitude of 34εDsrAB is similar to the median value of experimental observations compiled from all known published work, where 34εr-p = 16.1‰ (r – p indicates reactant versus product, n = 648. This value closely matches those of MSR operating at high sulfate reduction rates in both laboratory chemostat experiments (34εSO4-H2S = 17.3±1.5‰ and in modern marine sediments (34εSO4-H2S = 17.3±3.8‰. Targeting the direct isotopic consequences of a specific enzymatic processes is a fundamental step toward a biochemical foundation for reinterpreting the biogeochemical and geobiological sulfur isotope records in modern

  20. Isotope analysis in the transmission electron microscope

    OpenAIRE

    Susi, Toma; Hofer, Christoph; Argentero, Giacomo; Leuthner, Gregor T.; Pennycook, Timothy J.; Mangler, Clemens; Meyer, Jannik C.; Kotakoski, Jani

    2016-01-01

    The {\\AA}ngstr\\"om-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either $^{12}$C or $^{13}$C and describe the proc...

  1. Nickel isotopic composition of the mantle

    Science.gov (United States)

    Gall, Louise; Williams, Helen M.; Halliday, Alex N.; Kerr, Andrew C.

    2017-02-01

    This paper presents a detailed high-precision study of Ni isotope variations in mantle peridotites and their minerals, komatiites as well as chondritic and iron meteorites. Ultramafic rocks display a relatively large range in δ60 Ni (permil deviation in 60 Ni /58 Ni relative to the NIST SRM 986 Ni isotope standard) for this environment, from 0.15 ± 0.07‰ to 0.36 ± 0.08‰, with olivine-rich rocks such as dunite and olivine cumulates showing lighter isotope compositions than komatiite, lherzolite and pyroxenite samples. The data for the mineral separates shed light on the origin of these variations. Olivine and orthopyroxene display light δ60 Ni whereas clinopyroxene and garnet are isotopically heavy. This indicates that peridotite whole-rock δ60 Ni may be controlled by variations in modal mineralogy, with the prediction that mantle melts will display variable δ60 Ni values due to variations in residual mantle and cumulate mineralogy. Based on fertile peridotite xenoliths and Phanerozoic komatiite samples it is concluded that the upper mantle has a relatively homogeneous Ni isotope composition, with the best estimate of δ60Nimantle being 0.23 ± 0.06‰ (2 s.d.). Given that >99% of the Ni in the silicate Earth is located in the mantle, this also defines the Ni isotope composition of the Bulk Silicate Earth (BSE). This value is nearly identical to the results obtained for a suite of chondrites and iron meteorites (mean δ60 Ni 0.26 ± 0.12‰ and 0.29 ± 0.10‰, respectively) showing that the BSE is chondritic with respect to its Ni isotope composition, with little to no Ni mass-dependent isotope fractionation resulting from core formation.

  2. Metastasic bone pain management with radioactive isotopes

    OpenAIRE

    Juan Coya Viña

    2005-01-01

    Pain is the commonest clinical manifestation of bone metastases. Its treatment is palliative in nature, and consists of chemotherapy, radiotherapy, hormonotherapy, diphosphonates, and drug therapy (i. e., opiates). Radioactive isotopes represent an appealing alternative to conventional treatment modalities. Among the different types of isotopes, wide clinical experience with 153Sm has been obtained in this laboratory. In the present study, 94 patients (mean age = 65 years), who had been diagn...

  3. IUPAC Periodic Table of the Isotopes

    Science.gov (United States)

    Holden, N.E.; Coplen, T.B.; Böhlke, J.K.; Wieser, M.E.; Singleton, G.; Walczyk, T.; Yoneda, S.; Mahaffy, P.G.; Tarbox, L.V.

    2011-01-01

    For almost 150 years, the Periodic Table of the Elements has served as a guide to the world of elements by highlighting similarities and differences in atomic structure and chemical properties. To introduce students, teachers, and society to the existence and importance of isotopes of the chemical elements, an IUPAC Periodic Table of the Isotopes (IPTI) has been prepared and can be found as a supplement to this issue.

  4. Isotope separation in a "seeded beam%".

    Science.gov (United States)

    Anderson, J B; Davidovits, P

    1975-02-21

    A new method of separating isotopes in a gaseous mixture is described. The method takes advantage of the differences in velocities of isotopic species in a molecular beam formed by expansion of the mixture with a light gas from a nozzle source. For the separation of the hexafluorides of uranium-235 and uranium-238 the technique has an estimated separative work factor about 500 times higher than the gaseous diffusion process and 100 times higher than the curved-jet method.

  5. The origin of volatile element depletion in early solar system material: Clues from Zn isotopes in chondrules

    Science.gov (United States)

    Pringle, Emily A.; Moynier, Frédéric; Beck, Pierre; Paniello, Randal; Hezel, Dominik C.

    2017-06-01

    Volatile lithophile elements are depleted in the different planetary materials to various degrees, but the origin of these depletions is still debated. Stable isotopes of moderately volatile elements such as Zn can be used to understand the origin of volatile element depletions. Samples with significant volatile element depletions, including the Moon and terrestrial tektites, display heavy Zn isotope compositions (i.e. enrichment of 66Zn vs. 64Zn), consistent with kinetic Zn isotope fractionation during evaporation. However, Luck et al. (2005) found a negative correlation between δ66Zn and 1/[Zn] between CI, CM, CO, and CV chondrites, opposite to what would be expected if evaporation caused the Zn abundance variations among chondrite groups. We have analyzed the Zn isotope composition of multiple samples of the major carbonaceous chondrite classes: CI (1), CM (4), CV (2), CO (4), CB (2), CH (2), CK (4), and CK/CR (1). The bulk chondrites define a negative correlation in a plot of δ66Zn vs 1/[Zn], confirming earlier results that Zn abundance variations among carbonaceous chondrites cannot be explained by evaporation. Exceptions are CB and CH chondrites, which display Zn systematics consistent with a collisional formation mechanism that created enrichment in heavy Zn isotopes relative to the trend defined by CI-CK. We further report Zn isotope analyses of chondrite components, including chondrules from Allende (CV3) and Mokoia (CV3), as well as an aliquot of Allende matrix. All chondrules are enriched in light Zn isotopes (∼500 ppm on 66Zn/64Zn) relative to the bulk, contrary to what would be expected if Zn were depleted during evaporation, on the other hand the matrix has a complementary heavy isotope composition. We report sequential leaching experiments in un-equilibrated ordinary chondrites, which show sulfides are isotopically heavy compared to silicates and the bulk meteorite by ca. +0.65 per mil on 66Zn/64Zn. We suggest isotopically heavy sulfides were

  6. Geochemical and isotopic data for restricting seawater intrusion and groundwater circulation in a series of typical volcanic islands in the South China Sea.

    Science.gov (United States)

    Zhang, Wenjie; Chen, Xi; Tan, Hongbing; Zhang, Yanfei; Cao, Jifu

    2015-04-15

    The decline of groundwater table and deterioration of water quality related to seawater have long been regarded as a crucial problem in coastal regions. In this work, a hydrogeologic investigation using combined hydrochemical and isotopic approaches was conducted in the coastal region of the South China Sea near the Leizhou peninsular to provide primary insight into seawater intrusion and groundwater circulation. Hydrochemical and isotopic data show that local groundwater is subjected to anthropogenic activities and geochemical processes, such as evaporation, water-rock interaction, and ion exchange. However, seawater intrusion driven by the over-exploitation of groundwater and insufficient recharge is the predominant factor controlling groundwater salinization. Systematic and homologic isotopic characteristics of most samples suggest that groundwater in volcanic area is locally recharged and likely caused by modern precipitation. However, very depleted stable isotopes and extremely low tritium of groundwater in some isolated aquifers imply a dominant role of palaeowater. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. The discovery of isotopes a complete compilation

    CERN Document Server

    Thoennessen, Michael

    2016-01-01

    This book describes the exciting discovery of every isotope observed on earth to date, which currently numbers some 3000. For each isotope a short essay highlights the authors of the first publication for the isotope, the laboratory and year where and when the isotope was discovered, as well as details about the production and detection methods used. In controversial cases previously claims are also discussed. At the end a comprehensive table lists all isotopes sorted by elements and a complete list of references. Preliminary versions of these paragraphs have been published over the last few years as separate articles in the journal "Atomic Data and Nuclear Data Tables". The work re-evaluates all assignments judging them with a uniform set of criteria. In addition, the author includes over 100 new isotopes which have been discovered since the articles published. This book is a source of information for researchers as well as enthusiastic laymen alike. From the prepublication review: “The explanations focus ...

  8. Stable water isotopes in the MITgcm

    Science.gov (United States)

    Völpel, Rike; Paul, André; Krandick, Annegret; Mulitza, Stefan; Schulz, Michael

    2017-08-01

    We present the first results of the implementation of stable water isotopes in the Massachusetts Institute of Technology general circulation model (MITgcm). The model is forced with the isotopic content of precipitation and water vapor from an atmospheric general circulation model (NCAR IsoCAM), while the fractionation during evaporation is treated explicitly in the MITgcm. Results of the equilibrium simulation under pre-industrial conditions are compared to observational data and measurements of plankton tow records (the oxygen isotopic composition of planktic foraminiferal calcite). The broad patterns and magnitude of the stable water isotopes in annual mean seawater are well captured in the model, both at the sea surface as well as in the deep ocean. However, the surface water in the Arctic Ocean is not depleted enough, due to the absence of highly depleted precipitation and snowfall. A model-data mismatch is also recognizable in the isotopic composition of the seawater-salinity relationship in midlatitudes that is mainly caused by the coarse grid resolution. Deep-ocean characteristics of the vertical water mass distribution in the Atlantic Ocean closely resemble observational data. The reconstructed δ18Oc at the sea surface shows a good agreement with measurements. However, the model-data fit is weaker when individual species are considered and deviations are most likely attributable to the habitat depth of the foraminifera. Overall, the newly developed stable water isotope package opens wide prospects for long-term simulations in a paleoclimatic context.

  9. Stable water isotopes in the MITgcm

    Directory of Open Access Journals (Sweden)

    R. Völpel

    2017-08-01

    Full Text Available We present the first results of the implementation of stable water isotopes in the Massachusetts Institute of Technology general circulation model (MITgcm. The model is forced with the isotopic content of precipitation and water vapor from an atmospheric general circulation model (NCAR IsoCAM, while the fractionation during evaporation is treated explicitly in the MITgcm. Results of the equilibrium simulation under pre-industrial conditions are compared to observational data and measurements of plankton tow records (the oxygen isotopic composition of planktic foraminiferal calcite. The broad patterns and magnitude of the stable water isotopes in annual mean seawater are well captured in the model, both at the sea surface as well as in the deep ocean. However, the surface water in the Arctic Ocean is not depleted enough, due to the absence of highly depleted precipitation and snowfall. A model–data mismatch is also recognizable in the isotopic composition of the seawater–salinity relationship in midlatitudes that is mainly caused by the coarse grid resolution. Deep-ocean characteristics of the vertical water mass distribution in the Atlantic Ocean closely resemble observational data. The reconstructed δ18Oc at the sea surface shows a good agreement with measurements. However, the model–data fit is weaker when individual species are considered and deviations are most likely attributable to the habitat depth of the foraminifera. Overall, the newly developed stable water isotope package opens wide prospects for long-term simulations in a paleoclimatic context.

  10. Iron isotopic fractionation during continental weathering

    Energy Technology Data Exchange (ETDEWEB)

    Fantle, Matthew S.; DePaolo, Donald J.

    2003-10-01

    The biological activity on continents and the oxygen content of the atmosphere determine the chemical pathways through which Fe is processed at the Earth's surface. Experiments have shown that the relevant chemical pathways fractionate Fe isotopes. Measurements of soils, streams, and deep-sea clay indicate that the {sup 56}Fe/{sup 54}Fe ratio ({delta}{sup 56}Fe relative to igneous rocks) varies from +1{per_thousand} for weathering residues like soils and clays, to -3{per_thousand} for dissolved Fe in streams. These measurements confirm that weathering processes produce substantial fractionation of Fe isotopes in the modern oxidizing Earth surface environment. The results imply that biologically-mediated processes, which preferentially mobilize light Fe isotopes, are critical to Fe chemistry in weathering environments, and that the {delta}{sup 56}Fe of marine dissolved Fe should be variable and negative. Diagenetic reduction of Fe in marine sediments may also be a significant component of the global Fe isotope cycle. Iron isotopes provide a tracer for the influence of biological activity and oxygen in weathering processes through Earth history. Iron isotopic fractionation during weathering may have been smaller or absent in an oxygen-poor environment such as that of the early Precambrian Earth.

  11. Identification of isotopically primitive interplanetary dust particles: A NanoSIMS isotopic imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Floss, C; Stadermann, F J; Bradley, J P; Dai, Z R; Bajt, S; Graham, G; Lea, A S

    2005-09-02

    We have carried out a comprehensive survey of the isotopic compositions (H, B, C, N, O, S) of a suite of interplanetary dust particles (IDPs), including both cluster and individual particles. Isotopic imaging with the NanoSIMS shows the presence of numerous discrete hotspots that are strongly enriched in {sup 15}N, including the largest {sup 15}N enrichments ({approx}1300 {per_thousand}) observed in IDPs to date. A number of the IDPs also contain larger regions with more modest enrichments in {sup 15}N, leading to average bulk N isotopic compositions that are {sup 15}N-enriched in these IDPs. Although C isotopic compositions are normal in most of the IDPs, two {sup 15}N-rich N-hotspots have correlated {sup 13}C anomalies. CN{sup -}/C{sup -} ratios suggest that most of the {sup 15}N-rich hotspots are associated with relatively N-poor carbonaceous matter, although specific carriers have not been determined. H isotopic distributions are similar to those of N: D anomalies are present both as distinct very D-rich hotspots and as larger regions with more modest enrichments. Nevertheless, H and N isotopic anomalies are not directly correlated, consistent with results from previous studies. Oxygen isotopic imaging shows the presence of abundant presolar silicate grains in the IDPs. The O isotopic compositions of the grains are similar to those found in presolar oxide and silicate grains from primitive meteorites. Most of the silicate grains in the IDPs have isotopic ratios consistent with meteoritic Group 1 oxide grains, indicating origins in oxygen-rich red giant and asymptotic giant branch stars, but several presolar silicates exhibit the {sup 17}O and {sup 18}O enrichments of Group 4 oxide grains, whose origin is less well understood. Based on their N isotopic compositions, the IDPs studied here can be divided into two groups. One group is characterized as being ''isotopically primitive'' and consists of those IDPs that have anomalous bulk N isotopic

  12. Relationships between Lu-Hf and Sm-Nd isotopic systems in the global sedimentary system

    Science.gov (United States)

    Vervoort, Jeff D.; Patchett, P. Jonathan; Blichert-Toft, Janne; Albarède, Francis

    1999-04-01

    We report new Hf (and Nd) data for more than 100 sedimentary samples, recent to Archean in age, from a wide range of depositional environments. These data document the behavior of Lu-Hf and Sm-Nd isotopic systems in the global sedimentary system. In conjunction with existing data for mantle-derived rocks, we now have reasonable constraints on coupled Hf-Nd isotopic behavior in the crust and mantle. Lu/Hf and Hf isotopic compositions are strongly fractionated between muds and sands in passive margin sediments due to concentration of low Lu/Hf, low 176Hf/177Hf, Hf-rich zircons in mature sands. In active margin settings, Lu-Hf fractionation due to the `zircon effect' is minor due to the less weathered and more juvenile character of the sediments. Nd isotopic compositions are not highly fractionated by sedimentary sorting because heavy minerals, also rich in REEs, do not fractionate Sm-Nd efficiently. The lack of a large and systematic fractionation at active margins means that no significant Hf-Nd decoupling occurs here. This is important because sediments at active margins are the most likely to be recycled to the mantle. Hf-Nd isotopic data for all terrestrial samples fall along a single coherent trend (ɛHf=1.36ɛNd+2.95) which we call the `terrestrial array'. This array is composed of two complementary components: a mantle array (ɛHf=1.33ɛNd+3.19, defined by all oceanic basalts; and a crustal array (ɛHf=1.34ɛNd+2.82), defined by sediments, continental basalts, granitoids, and juvenile crustal rocks. The similarity of the crustal and mantle arrays indicates that no large-scale Hf-Nd decoupling occurs between the crust and mantle. The coherency of the terrestrial Hf-Nd array implies mixing within the mantle, due to stirring processes, and also within the crust, due to homogenization by collective sedimentary processes. In addition, tight Hf-Nd covariation may also imply that efficient crust to mantle recycling has modulated isotopic correlation in the silicate

  13. Storage-discharge hysteresis and its impact on stream flow O-18 and D isotope signatures

    Science.gov (United States)

    Pfister, Laurent; Klaus, Julian; Carrer, Gwenael; Hissler, Christophe; Martínez-Carreras, Núria; Rodriguez, Nicolas; McDonnell, Jeffrey J.

    2017-04-01

    Catchment storage-discharge relationships are known to be non-linear and to exhibit hysteretic patterns. Antecedent storage and catchment scale largely control the degree of the hysteresis - as a translation of differences in velocities and celerities differently in each individual catchment. Following up on recent calls in the literature for a more systematic combination of hydrograph and stable isotope investigations, here we focus on catchment storage dynamics and how these may be correlated with isotopic signatures of O-18 and D in stream flow. Our study area is located in the Alzette River basin and consists of 12 nested catchments, covering a wide range of physiographic settings with clean and mixed bedrock geology, landuse, soil types, and topography. First, we used daily water balance calculations over an 8-year period (2006-2014) to estimate daily storage deficits. The daily storage deficit-discharge pairs were found to evolve along an envelope line that is tangential to hysteretic loops of these same variables. Each catchment's envelope line was found to have a distinct slope - the variety of slopes being controlled by bedrock type and its subsequent permeability. Next, we investigated the dynamics of isotopic signatures of O-18 and D in stream flow along the complete range of observed daily discharge and storage deficit values. A common feature in most (but not all) of our study catchments is that isotopic signals became more and more depleted as storage deficits tended to zero (i.e. saturation). Likewise, isotopic depletion in streamflow O-18 and D was highest when storage deficits were smallest and discharge values highest. Our investigation of isotopic signatures in stream flow across 12 catchments through multiple wetting-up and drying cycles has revealed relationships between catchment bedrock geology, storage and isotopic signatures of O-18 and D in stream flow. These signatures are largely (but not exclusively) controlled by storage dynamics on a

  14. Fractionation of silver isotopes in native silver explained by redox reactions

    Science.gov (United States)

    Mathur, Ryan; Arribas, Antonio; Megaw, Peter; Wilson, Marc; Stroup, Steven; Meyer-Arrivillaga, Danilo; Arribas, Isabel

    2018-03-01

    Scant data exist on the silver isotope composition of native silver specimens because of the relative newness of the technique. This study increases the published dataset by an order of magnitude and presents 80 silver new isotope analyses from native silver originating from a diverse set of worldwide deposits (8 deposit types, 33 mining districts in five continents). The measured isotopic range (defined as δ109Ag/107Ag in per mil units compared to NIST 978 Ag isotope standard) is +2.1 to -0.86‰ (2σ errors less than 0.015); with no apparent systematic correlations to date with deposit type or even within districts. Importantly, the data centering on 0‰ all come from high temperature hypogene/primary deposits whereas flanking and overlapping data represent secondary supergene deposits. To investigate the causes for the more fractionated values, several laboratory experiments involving oxidation of silver from natural specimens of Ag-rich sulfides and precipitation and adsorption of silver onto reagent grade MnO2 and FeOOH were conducted. Simple leach experiments demonstrate little Ag isotope fractionation occurred through oxidation of Ag from native Ag (Δsolution-native109Ag = 0.12‰). In contrast, significant fractionation occurred through precipitation of native Ag onto MnO2 (up to Δsolution-MnO2109Ag = 0.68‰, or 0.3amu). Adsorption of silver onto the MnO2 and FeOOH did not produce as large fractionation as precipitation (mean value of Δsolution-MnO2109Ag = 0.10‰). The most likely cause for the isotopic variations seen relates to redox effects such as the reduction of silver from Ag (I) to Ag° that occurs during precipitation onto the mineral surface. Since many Ag deposits have halos dominated by MnO2 and FeOOH phases, potential may exist for the silver isotope composition of ores and surrounding geochemical haloes to be used to better understand ore genesis and potential exploration applications. Aside from the Mn oxides, surface fluid silver

  15. What Hf isotopes in zircon tell us about crust-mantle evolution

    Science.gov (United States)

    Iizuka, Tsuyoshi; Yamaguchi, Takao; Itano, Keita; Hibiya, Yuki; Suzuki, Kazue

    2017-03-01

    The 176Lu-176Hf radioactive decay system has been widely used to study planetary crust-mantle differentiation. Of considerable utility in this regard is zircon, a resistant mineral that can be precisely dated by the U-Pb chronometer and record its initial Hf isotope composition due to having low Lu/Hf. Here we review zircon U-Pb age and Hf isotopic data mainly obtained over the last two decades and discuss their contributions to our current understanding of crust-mantle evolution, with emphasis on the Lu-Hf isotope composition of the bulk silicate Earth (BSE), early differentiation of the silicate Earth, and the evolution of the continental crust over geologic history. Meteorite zircon encapsulates the most primitive Hf isotope composition of our solar system, which was used to identify chondritic meteorites best representative of the BSE (176Hf/177Hf = 0.282793 ± 0.000011; 176Lu/177Hf = 0.0338 ± 0.0001). Hadean-Eoarchean detrital zircons yield highly unradiogenic Hf isotope compositions relative to the BSE, providing evidence for the development of a geochemically enriched silicate reservoir as early as 4.5 Ga. By combining the Hf and O isotope systematics, we propose that the early enriched silicate reservoir has resided at depth within the Earth rather than near the surface and may represent a fractionated residuum of a magma ocean underlying the proto-crust, like urKREEP beneath the anorthositic crust on the Moon. Detrital zircons from world major rivers potentially provide the most robust Hf isotope record of the preserved granitoid crust on a continental scale, whereas mafic rocks with various emplacement ages offer an opportunity to trace the Hf isotope evolution of juvenile continental crust (from εHf[4.5 Ga] = 0 to εHf[present] = + 13). The river zircon data as compared to the juvenile crust composition highlight that the supercontinent cycle has controlled the evolution of the continental crust by regulating the rates of crustal generation and intra

  16. Petrographic and C & O isotopic characteristics of the earliest stages of aqueous alteration of CM chondrites

    Science.gov (United States)

    Vacher, Lionel G.; Marrocchi, Yves; Villeneuve, Johan; Verdier-Paoletti, Maximilien J.; Gounelle, Matthieu

    2017-09-01

    CM chondrites form the largest group of hydrated meteorites and span a wide range of alteration states, with the Paris meteorite being the least altered CM described to date. Ca-Carbonates are powerful proxies for the alteration conditions of CMs because they are direct snapshots of the chemical and isotopic compositions of the parent fluids. Here, we report a petrographic and a C isotope and O isotope survey of Ca-carbonates in Paris in order to better characterize the earliest stages of aqueous alteration. Petrographic observations show that Paris contains two distinct populations of Ca-carbonates: Type 1a Ca-carbonates, which are surrounded by rims of tochilinite/cronstedtite intergrowths (TCIs), and new Type 0 Ca-carbonates, which do not exhibit the TCI rims. The TCI rims of Type 1a Ca-carbonates commonly outline euhedral crystal faces, demonstrating that these Ca-carbonates were (i) partially or totally pseudomorphosed by TCI and (ii) precipitated at the earliest stages of aqueous alteration, before Type 0 Ca-carbonates. Isotopic measurements show that Paris' Ca-carbonates have δ13C values that range from 19 to 80‰ (PDB), δ18O values that range from 29 to 41%, and δ17O values that range from 13 to 24‰ (SMOW). According to the δ13C-δ18O values of Paris' Ca-carbonates, we developed a new alteration model that involves (i) the equilibration of a primordial 17,18O-rich water (PW) with 16O-rich anhydrous silicates and (ii) varying contribution of 12C- and 13C-rich soluble organic matter (SOMs). It also suggests that many parameters control the C and O isotopic composition of Ca-carbonates, the principles being the degree of isotopic equilibration between the PW and the anhydrous silicates, the respective contribution of 12C and 13C-rich SOMs as well as the thermal evolution of CM parent bodies. Consequently, we suggest that CM Ca-carbonates could record both positive and negative δ13C-δ18O relationships, but a systematic correspondence is probably absent

  17. Geochemical evidence of an extraterrestrial component in impact melt breccia from the Paleoproterozoic Dhala impact structure, India

    Science.gov (United States)

    Pati, Jayanta Kumar; Qu, Wen Jun; Koeberl, Christian; Reimold, Wolf Uwe; Chakarvorty, Munmun; Schmitt, Ralf Thomas

    2017-04-01

    The Paleoproterozoic Dhala structure with an estimated diameter of 11 km is a confirmed complex impact structure located in the central Indian state of Madhya Pradesh in predominantly granitic basement (2.65 Ga), in the northwestern part of the Archean Bundelkhand craton. The target lithology is granitic in composition but includes a variety of meta-supracrustal rock types. The impactites and target rocks are overlain by 1.7 Ga sediments of the Dhala Group and the Vindhyan Supergroup. The area was cored in more than 70 locations and the subsurface lithology shows pseudotachylitic breccia, impact melt breccia, suevite, lithic breccias, and postimpact sediments. Despite extensive erosion, the Dhala structure is well preserved and displays nearly all the diagnostic microscopic shock metamorphic features. This study is aimed at identifying the presence of an impactor component in impact melt rock by analyzing the siderophile element concentrations and rhenium-osmium isotopic compositions of four samples of impactites (three melt breccias and one lithic breccia) and two samples of target rock (a biotite granite and a mafic intrusive rock). The impact melt breccias are of granitic composition. In some samples, the siderophile elements and HREE enrichment observed are comparable to the target rock abundances. The Cr versus Ir concentrations indicate the probable admixture of approximately 0.3 wt.% of an extraterrestrial component to the impact melt breccia. The Re and Os abundances and the 187Os/188Os ratio of 0.133 of one melt breccia specimen confirm the presence of an extraterrestrial component, although the impactor type characterization still remains inconclusive.

  18. In-situ Nd isotope measurements on accessory minerals: Insights into isotope equilibration during metamorphism

    Science.gov (United States)

    Hammerli, Johannes; Spandler, Carl; Kemp, Tony; Pirard, Cassian

    2015-04-01

    Understanding isotope equilibration processes during metamorphism has huge implications for a range of geoscience applications, ranging from provenance studies of sedimentary units to the origin of magmas and ore bodies. Furthermore, recent claims of isotope disequilibrium situations during the melting of continental crust have questioned the reliability of using certain isotope systems to track magma sources. Our recent work investigated a prograde sequence of high-temperature, low-pressure (350-650 ˚C, ~3-5 kbar) metasedimentary rocks from the Mt. Lofty Ranges, South Australia that underwent widespread pervasive fluid flow at peak metamorphism. In situ Nd-isotope analyses by LA-MC-ICP-MS found that the detrital signature of apatite survives temperatures of 500 °C. However, the observed isotope equilibration of REE-bearing accessory minerals at ~600 °C, before the onset of partial melting, suggests that isotope disequilibrium is unlikely during high-grade metamorphism of upper crustal rocks where fluid induced melting takes place. Here, we extend our research to metasedimentary rocks from (ultra)-high pressure metamorphic terrains from northern New Caledonia, and Dabieshan, China that represent pressure and temperature conditions found in subduction zones. Our study helps to understand isotope equilibration processes from heterogeneous protoliths as well as the impact of retrogression and the resetting of isotope systems over a pressure-temperature range from ~350 °C to 700 °C and ~15 kbar to 40 kbar. Nd isotope analyses of apatite, allanite, titanite, xenotime, monazite, lawsonite and epidote in pelitic and psammitic samples allow the investigation of isotope equilibration on a mineral and sub-mineral scale, as well as comparison with traditional bulk rock isotope analyses. Our preliminary results show that under high-pressure conditions (~20 to 30 kbar) and temperatures to ~650 °C, REE-bearing phases show variable ɛNd values in some cases. These

  19. Substrate hydrophobicity and cell composition influence the extent of rate limitation and masking of isotope fractionation during microbial reductive dehalogenation of chlorinated ethenes.

    Science.gov (United States)

    Renpenning, Julian; Rapp, Insa; Nijenhuis, Ivonne

    2015-04-07

    This study investigated the effect of intracellular microscale mass transfer on microbial carbon isotope fractionation of tetrachloroethene (PCE) and trichloroethene (TCE). Significantly stronger isotope fractionation was observed for crude extracts vs intact cells of Sulfurospirillum multivorans, Geobacter lovleyi, Desulfuromonas michiganensis, Desulfitobacterium hafniense strain PCE-S, and Dehalobacter restrictus. Furthermore, carbon stable isotope fractionation was stronger for microorganisms with a Gram-positive cell envelope compared to those with a Gram-negative cell envelope. Significant differences were observed between model organisms in cellular sorption capacity for PCE (S. multivorans-K(d-PCE) = 0.42-0.51 L g(-1); D. hafniense-K(d-PCE) = 0.13 L g(-1)), as well as in envelope hydrophobicity (S. multivorans 33.0° to 72.2°; D. hafniense 59.1° to 60.8°) when previously cultivated with fumarate or PCE as electron acceptor, but not for TCE. Cell envelope properties and the tetrachloroethene reductive dehalogenase (PceA-RDase) localization did not result in significant effects on observed isotope fractionation of TCE. For PCE, however, systematic masking of isotope effects as a result of microscale mass transfer limitation at microbial membranes was observed, with carbon isotope enrichment factors of -2.2‰, -1.5 to -1.6‰, and -1.0‰ (CI95% isotope fractionation is determined by (1) hydrophobicity of the degraded compound, (2) properties of the cell envelope, and (3) the localization of the reacting enzyme.

  20. KIPS kilowatt isotope power system

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    This Control System topical report covers basic control requirements, selection of control system and a recent review of an electromechanical approach to the flow control valve. Section I covers the basic control requirements for Organic Rankine cycle systems, particular requirements for an isotope fueled space power system, and special requirements imposed by launch, Shuttle deployment and spacecraft requirements. Various control devices which can be used to meet system requirements are discussed. In Section II, various combinations of control functions and devices are presented with comments as to the suitability of each for the intended application. This is essentially a review of the selection process used to pick the present KIPS control system. The formal trade-off matrix, component description, and system selection, as prepared for Design Reviews 2 and 3, is included as Appendix A to the report. Section 3 covers the recently completed design of an electronic-electromechanical flow control valve and compares this approach to the thermal bulb-hydro-mechanical flow control valve baseline. The results of this comparative study indicate that the present configuration is preferable to an electrical valve.

  1. Evidence of a warm early instrumental period found in temperature related water isotope records from high elevation Alpine ice cores

    Science.gov (United States)

    Bohleber, Pascal; Schöner, Wolfgang; Wagenbach, Dietmar

    2015-04-01

    The variability of water isotopes (delta-O18 or delta-D) preserved in Alpine glacier ice may provide mid-latitude temperature proxy records supplementing respective information from other archives. In order to archive long term records (i.e. exceeding 100 years) the limited glacier depth at suitable Alpine drill sites requires a relatively low net accumulation rate. In this respect, the cold glacier saddle Colle Gnifetti (CG) is the unique drilling site in the European Alps offering ice core records substantially exceeding the instrumental period. However, the unique low net accumulation at CG is characterised by strong spatio-temporal variability causing depositional noise that strongly challenges the interpretation of the ice core isotope records in terms of net temperature change. Here we present our findings from comparing stable water isotope records of the CG multi core array to a site-specific temperature time series. The latter is synthesized from high elevation stations of the instrumental HISTALP network considering among others the temperature shift from the accumulation bias towards growing seasons. Within the last century dedicated time series analysis reveals a common signal in the (supra-) decadal components of the instrumental temperature and isotope records. Extending the comparison over the entire 250 years instrumental period, systematic discrepancies are found within the early instrumental period (EIP). The delta-O18 record shows an overall decreasing trend from 1760 to 1890 AD, which is not reflected in the temperature record. However, using high Alpine summer temperature lacking the latest EIP adjustment, the long-term trends between isotope and instrumental data are in better agreement. The overall mean of the isotope based temperature in the EIP indicates substantially warmer levels than the EIP-corrected instrumental temperature. It differs, however, not significantly with respect to the non-EIP-corrected temperature mean. Although the main

  2. Production cross sections of neutron rich isotopes from a 82Se beam

    Science.gov (United States)

    Tarasov, O. B.; Morrissey, D. J.; Amthor, A. M.; Bandura, L.; Baumann, T.; Bazin, D.; Berryman, J. S.; Chubarian, G.; Fukuda, N.; Gade, A.; Ginter, T. N.; Hausmann, M.; Inabe, N.; Kubo, T.; Pereira, J.; Portillo, M.; Sherrill, B. M.; Stolz, A.; Sumithrarachchi, C.; Thoennessen, M.; Weisshaar, D.

    2013-03-01

    Production cross sections for neutron-rich nuclei from the fragmentation of a 82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions of 122 neutron-rich isotopes of elements 11 <= Z <= 32 were determined by varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including several isotopes first observed in this work. These are the most neutron-rich nuclides of the elements 22 <= Z <= 25 (64Ti, 67V, 69Cr, 72Mn). One event was registered consistent with 70Cr, and another one with 75Fe. A one-body Qg systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. The current results confirm those of our previous experiment with a 76Ge beam: enhanced production cross sections for neutron-rich fragments near Z = 20.

  3. Production cross sections of neutron rich isotopes from a 82Se beam

    CERN Document Server

    Tarasov, O B; Amthor, A M; Bandura, L; Baumann, T; Bazin, D; Berryman, J S; Chubarian, G; Fukuda, N; Gade, A; Ginter, T N; Hausmann, M; Inabe, N; Kubo, T; Pereira, J; Portillo, M; Sherrill, B M; Stolz, A; Sumithrarachchi, C; Thoennessen, M; Weisshaar, D

    2012-01-01

    Production cross sections for neutron-rich nuclei from the fragmentation of a 82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions of 122 neutron-rich isotopes of elements $11 \\le Z \\le 32$ were determined by varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including several isotopes first observed in this work. These are the most neutron-rich nuclides of the elements $22 \\le Z \\le 25$ (64Ti, 67V, 69Cr, 72Mn). One event was registered consistent with 70Cr, and another one with 75Fe. A one-body Qg systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. The current results confirm those of our previous experiment with a 76Ge beam: enhanced production cross sections for neutron-rich fragments near Z=20.

  4. Oxygen isotope variations at the margin of a CAI records circulation within the solar nebula.

    Science.gov (United States)

    Simon, Justin I; Hutcheon, Ian D; Simon, Steven B; Matzel, Jennifer E P; Ramon, Erick C; Weber, Peter K; Grossman, Lawrence; DePaolo, Donald J

    2011-03-04

    Micrometer-scale analyses of a calcium-, aluminum-rich inclusion (CAI) and the characteristic mineral bands mantling the CAI reveal that the outer parts of this primitive object have a large range of oxygen isotope compositions. The variations are systematic; the relative abundance of (16)O first decreases toward the CAI margin, approaching a planetary-like isotopic composition, then shifts to extremely (16)O-rich compositions through the surrounding rim. The variability implies that CAIs probably formed from several oxygen reservoirs. The observations support early and short-lived fluctuations of the environment in which CAIs formed, either because of transport of the CAIs themselves to distinct regions of the solar nebula or because of varying gas composition near the proto-Sun.

  5. Chemical investigations of isotope separation on line target units for carbon and nitrogen beams

    CERN Document Server

    Franberg, H; Gäggeler, H W; Köster, U

    2006-01-01

    Radioactive ion beams (RIBs) are of significant interest in a number of applications. Isotope separation on line (ISOL) facilities provide RIB with high beam intensities and good beam quality. An atom that is produced within the ISOL target will first diffuse out from the target material. During the effusion towards the transfer line and into the ion source the many contacts with the surrounding surfaces may cause unacceptable delays in the transport and, hence, losses of the shorter-lived isotopes. We performed systematic chemical investigations of adsorption in a temperature and concentration regime relevant for ISOL targets and ion source units, with regard to CO/sub x/ and NOmaterials are potential construction materials for the above-mentioned areas. Off-line and on-line tests have been performed using a gas thermochromatography setup with radioactive tracers. The experiments were performed at the production of tracers for atmospheric chemistry (PROTRAC) facility at the Paul Schener Institute in Villigen...

  6. Pb isotope evidence for crust-mantle interactions at late Archean convergent continental margins

    Science.gov (United States)

    Halla, Jaana

    2017-04-01

    The global Pb isotope systematics and geochemical diversification of late Archean granitoids indicate a change in a tectonic regime towards the Archean - Proterozoic boundary. After a long-term episodic formation of sodic TTGs of oceanic origin, convergent continental margins with abundant batholiths of potassic granitoids emerged between 3.0-2.5 Ga. The Pb isotope compositions of granitoids reflect a presence of crustal segments of different ages and demonstrate, together with geochemical features, that the batholiths involve both mantle- and crust-derived material. It seems that the increase in crust-mantle interactions, probably as a consequence of frequent slab breakoffs or delamination at convergent continental margins, caused multisource magmatism by triggering melting, metasomatism and hydrothermal activity in the mantle and crust, possibly reflecting an assembling supercontinent towards the end of the Archean.

  7. Detection of exogenous citric acid in fruit juices by stable isotope ratio analysis.

    Science.gov (United States)

    Jamin, Eric; Martin, Frédérique; Santamaria-Fernandez, Rebeca; Lees, Michèle

    2005-06-29

    A new method has been developed for measuring the D/H ratio of the nonexchangeable sites of citric acid by isotope ratio mass spectrometry (IRMS). Pure citric acid is transformed into its calcium salt and subsequently analyzed by pyrolysis-IRMS. The citric acid isolated from authentic fruit juices (citrus, pineapple, and red fruits) systematically shows higher D/H values than its nonfruit counterpart produced by fermentation of various sugar sources. The discrimination obtained with this simplified method is similar to that obtained previously by applying site specific isotopic fractionation-nuclear magnetic resonance (SNIF-NMR) to an ester derivative of citric acid. The combination of carbon 13 and deuterium measurements of extracted citric acid is proposed as a routine method for an optimum detection of exogenous citric acid in all kinds of fruit juices.

  8. Production of the PET isotope (11)C in hadron therapy via neutron knockout.

    Science.gov (United States)

    Simpson, E C

    2016-12-01

    Positron emitting isotopes such as (11)C and (10)C can be used for vital dose verification in hadron therapy. These isotopes are produced when the high energy (12)C primary beam particles undergo nuclear reactions within the patient. We discuss a model for calculating cross sections for the production (11)C in (12)C+(12)C collisions, applicable at hadron therapy energies. Good agreement with the available cross section measurements is found for (12)C(-1n), though more detailed, systematic measurements would be very valuable. Nuclear structure plays a crucial role in the reactions of light nuclei, particularly when those reactions are peripheral and involve only a few nucleons. For such reactions, nuclear structure has a strong influence on the energy and angular distribution of the cross section, and is an important consideration for reliable dose verification using (11)C in hadron therapy. Copyright © 2016. Published by Elsevier Ltd.

  9. Chemical stability of levoglucosan: an isotopic perspective

    Science.gov (United States)

    Sang, Xuefang; Gensch, Iulia; Schlag, Patrick; Wildt, Juergen; Laumer, Werner; Kammer, Beatrix; Tillmann, Ralf; Chitwan, Ojha; Heinichen, Gesa; Kiendler-scharr, Astrid

    2014-05-01

    Levoglucosan, used in receptor models as a specific tracer of biomass burning aerosols, has long been considered chemically stable in the atmosphere. Recent laboratory investigations found significant chemical degradation of levoglucosan when exposed to OH radicals (Hennigan et al., 2010). Stable carbon isotopic analyses, complementarily to concentration measurements, can provide additional evidence for physical and chemical processing in the atmosphere, since chemical processing causes changes in the relative abundance between heavy and light isotopes due to kinetic isotope effect (KIE). In this study, the chemical stability of levoglucosan was studied by exploring the isotopic fractionation of the reactant during the oxidation by OH. Mixed particles with levoglucosan and ammonium sulfate were generated in a continuous-stirred flow reactor and exposed to different levels of OH. Levoglucosan chemical degradation as function of OH exposure was derived from the decrease of levoglucosan/(NH4)2SO4 concentration ratios using aerosol mass spectrometry (AMS). Filter samples were collected for off-line isotopic analyses. Liquid extraction - Gas Chromatography - Isotope Ratio Mass Spectrometry (LE-GC-IRMS) was applied to measure stable carbon isotope ratios of levoglucosan. The observed d13C became more positive with increasing OH exposure, showing isotopic fractionations up to 3 ‰ at a reactant conversion of 45%. From the dependence of levoglucosan d13C on the OH exposure, a KIE of 1.00451 was derived, being within the range of predicted values for alkanes and alkenes with the same number of carbon atoms. With known source isotopic composition of levoglucosan in biomass burning aerosol (Sang et al., 2012), ambient measurements of levoglucosan d13C composition can therefore be used to determine the extent of chemical processing at the observation site. Reference: Hennigan, C. J., et al. 2010. Levoglucosan stability in biomass burning particles exposed to hydroxyl radicals

  10. Chromium isotope heterogeneity in the mantle

    Science.gov (United States)

    Xia, Jiuxing; Qin, Liping; Shen, Ji; Carlson, Richard W.; Ionov, Dmitri A.; Mock, Timothy D.

    2017-04-01

    To better constrain the Cr isotopic composition of the silicate Earth and to investigate potential Cr isotopic fractionation during high temperature geological processes, we analyzed the Cr isotopic composition of different types of mantle xenoliths from diverse geologic settings: fertile to refractory off-craton spinel and garnet peridotites, pyroxenite veins, metasomatised spinel lherzolites and associated basalts from central Mongolia, spinel lherzolites and harzburgites from North China, as well as cratonic spinel and garnet peridotites from Siberia and southern Africa. The δ53CrNIST 979 values of the peridotites range from - 0.51 ± 0.04 ‰ (2SD) to + 0.75 ± 0.05 ‰ (2SD). The results show a slight negative correlation between δ53Cr and Al2O3 and CaO contents for most mantle peridotites, which may imply Cr isotopic fractionation during partial melting of mantle peridotites. However, highly variable Cr isotopic compositions measured in Mongolian peridotites cannot be caused by partial melting alone. Instead, the wide range in Cr isotopic composition of these samples most likely reflects kinetic fractionation during melt percolation. Chemical diffusion during melt percolation resulted in light Cr isotopes preferably entering into the melt. Two spinel websterite veins from Mongolia have extremely light δ53Cr values of - 1.36 ± 0.04 ‰ and - 0.77 ± 0.06 ‰, respectively, which are the most negative Cr isotopic compositions yet reported for mantle-derived rocks. These two websterite veins may represent crystallization products from the isotopically light melt that may also metasomatize some peridotites in the area. The δ53Cr values of highly altered garnet peridotites from southern Africa vary from - 0.35 ± 0.04 ‰ (2SD) to + 0.12 ± 0.04 ‰ (2SD) and increase with increasing LOI (Loss on Ignition), reflecting a shift of δ53Cr to more positive values by secondary alteration. The Cr isotopic composition of the pristine, fertile upper mantle is

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

    Science.gov (United States)

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

    2017-06-01

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

  12. The isotope composition of inorganic germanium in seawater and deep sea sponges

    Science.gov (United States)

    Guillermic, Maxence; Lalonde, Stefan V.; Hendry, Katharine R.; Rouxel, Olivier J.

    2017-09-01

    Although dissolved concentrations of germanium (Ge) and silicon (Si) in modern seawater are tightly correlated, uncertainties still exist in the modern marine Ge cycle. Germanium stable isotope systematics in marine systems should provide additional constraints on marine Ge sources and sinks, however the low concentration of Ge in seawater presents an analytical challenge for isotopic measurement. Here, we present a new method of pre-concentration of inorganic Ge from seawater which was applied to measure three Ge isotope profiles in the Southern Ocean and deep seawater from the Atlantic and Pacific Oceans. Germanium isotopic measurements were performed on Ge amounts as low as 2.6 ng using a double-spike approach and a hydride generation system coupled to a MC-ICP-MS. Germanium was co-precipitated with iron hydroxide and then purified through anion-exchange chromatography. Results for the deep (i.e. >1000 m depth) Pacific Ocean off Hawaii (nearby Loihi Seamount) and the deep Atlantic off Bermuda (BATS station) showed nearly identical δ74/70Ge values at 3.19 ± 0.31‰ (2SD, n = 9) and 2.93 ± 0.10‰ (2SD, n = 2), respectively. Vertical distributions of Ge concentration and isotope composition in the deep Southern Ocean for water depth > 1300 m yielded an average δ74/70Ge = 3.13 ± 0.25‰ (2SD, n = 14) and Ge/Si = 0.80 ± 0.09 μmol/mol (2SD, n = 12). Significant variations in δ74/70Ge, from 2.62 to 3.71‰, were measured in the first 1000 m in one station of the Southern Ocean near Sars Seamount in the Drake Passage, with the heaviest values measured in surface waters. Isotope fractionation by diatoms during opal biomineralization may explain the enrichment in heavy isotopes for both Ge and Si in surface seawater. However, examination of both oceanographic parameters and δ74/70Ge values suggest also that water mass mixing and potential contribution of shelf-derived Ge also could contribute to the variations. Combining these results with new Ge isotope data

  13. Isotopic inferences of ancient biochemistries - Carbon, sulfur, hydrogen, and nitrogen

    Science.gov (United States)

    Schidlowski, M.; Hayes, J. M.; Kaplan, I. R.

    1983-01-01

    In processes of biological incorporation and subsequent biochemical processing sizable isotope effects occur as a result of both thermodynamic and kinetic fractionations which take place during metabolic and biosynthetic reactions. In this chapter a review is provided of earlier work and recent studies on isotope fractionations in the biogeochemical cycles of carbon, sulfur, hydrogen, and nitrogen. Attention is given to the biochemistry of carbon isotope fractionation, carbon isotope fractionation in extant plants and microorganisms, isotope fractionation in the terrestrial carbon cycle, the effects of diagenesis and metamorphism on the isotopic composition of sedimentary carbon, the isotopic composition of sedimentary carbon through time, implications of the sedimentary carbon isotope record, the biochemistry of sulfur isotope fractionation, pathways of the biogeochemical cycle of nitrogen, and the D/H ratio in naturally occurring materials.

  14. Site-Specific Carbon Isotopes in Organics

    Science.gov (United States)

    Piasecki, A.; Eiler, J. M.

    2012-12-01

    Natural organic molecules exhibit a wide range of internal site-specific isotope variation (i.e., molecules with same isotopic substitution type but different site). Such variations are generally unconstrained by bulk isotopic measurements. If known, site-specific variations might constrain temperatures of equilibrium, mechanisms of formation or consumption reactions, and possibly other details. For example, lipids can exhibit carbon isotope differences of up to 30‰ between adjacent carbon sites as a result of fractionations arising during decarboxylation of pyruvate and other steps in lipid biosynthesis(1). We present a method for site-specific carbon isotope analysis of propane, based on high-resolution, multi-collector gas source mass spectrometry, using a novel prototype instrument - the Thermo MAT 253 Ultra. This machine has an inlet system and electron bombardment ion source resembling those in conventional stable isotope gas source mass spectrometers, and the energy filter, magnet, and detector array resembling those in multi-collector ICPMS and TIMS. The detector array has 7 detector positions, 6 of which are movable, and each of which can collect ions with either a faraday cup (read through amplifiers ranging from 107-1012 ohms) or an SEM. High mass resolving power (up to 27,000, MRP = M/dM definition) is achieved through a narrow entrance slit, adjustable from 250 to 5 μm. Such resolution can cleanly separate isobaric interferences between isotopologues of organic molecules having the same cardinal mass (e.g., 13CH3 and 12CH2D). We use this technology to analyze the isotopologues and fragments of propane, and use such data to solve for the site-specific carbon isotope fractionation. By measuring isotopologues of both the one-carbon (13CH3) and the two-carbon (13C12CH4) fragment ion, we can solve for both bulk δ13C and the difference in δ13C between the terminal and central carbon position. We tested this method by analyzing mixtures between natural

  15. Spatial isotopic heterogeneity during the Guttenberg isotopic carbon excursion: Mechanisms and implications for craton-wide isotope gradients

    Science.gov (United States)

    Metzger, J. G.; Fike, D. A.

    2012-12-01

    The carbon isotopic compositions of carbonate carbon (δ13Ccarb) and organic carbon (δ13Corg) in marine limestones are frequently used as paleoenvironmental proxies and as chemostratigraphic tools for aligning strata. These functions are predicated upon the assumption that isotopic variability in these strata reflects the secular variation in the marine reservoir of dissolved inorganic carbon (DIC). As such, the utility of these isotopic systems largely depends on the assumed spatial homogeneity of marine δ13CDIC. While other isotope systems such as sulfate and strontium have been shown to be extremely well mixed in the modern ocean, a 1-2‰ range in δ13CDIC exists over the entire depth and latitude range of the ocean. This variability in δ13CDIC is largely the result of differences in the local balance of organic carbon fixation and export (increasing δ13CDIC) and/or organic carbon oxidation (decreasing δ13CDIC). The preservation of such isotopic variability in the geologic record has been advocated on several occasions. In particular, previous workers have argued for an ocean-to-interior seaway isotopic gradient in δ13Ccarb, δ13Corg, and ɛNd across Laurentia during the Late Ordovician across the interval that spans the Guttenberg Isotopic Carbon Excursion (GICE). Here we examine two Late Ordovician-aged sections from Missouri, USA that contain the GICE. At first glace, our data showed high degree of stratigraphic and lateral variability. Detailed petrographic and geochemical (e.g., trace element abundance) screening reveals that the majority of the isotopic heterogeneity in our sections is the result of local syndepositional/diagenetic alteration - and not the result of primary gradients in δ13CDIC between the localities examined. Our 'least-altered' δ13Ccarb profile matches closely with previously published records from Iowa; however, sections adjacent both to our locations in Missouri and to the similar δ13Ccarb profile in Iowa are characterized by

  16. Modeling nuclear volume isotope effects in crystals

    Science.gov (United States)

    Schauble, Edwin A.

    2013-01-01

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac–Hartree–Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor–crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium

  17. Modeling nuclear volume isotope effects in crystals.

    Science.gov (United States)

    Schauble, Edwin A

    2013-10-29

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from (119)Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium.

  18. U-Pb ages and Hf isotope compositions of zircons in plutonic rocks from the central Famatinian arc, Argentina

    Science.gov (United States)

    Otamendi, Juan E.; Ducea, Mihai N.; Cristofolini, Eber A.; Tibaldi, Alina M.; Camilletti, Giuliano C.; Bergantz, George W.

    2017-07-01

    The Famatinian arc formed around the South Iapetus rim during the Ordovician, when oceanic lithosphere subducted beneath the West Gondwana margin. We present combined in situ U-Th-Pb and Lu-Hf isotope analyses for zircon to gain insights into the origin and evolution of Famatinian magmatism. Zircon crystals sampled from four intermediate and silicic plutonic rocks confirm previous observations showing that voluminous magmatism took place during a relatively short pulse between the Early and Middle Ordovician (472-465 Ma). The entire zircon population for the four plutonic rocks yields coherent εHf negative values and spreads over several ranges of initial εHf(t) units (-0.3 to -8.0). The range of εHf units in detrital zircons of Famatinian metasedimentary rocks reflects a prolonged history of the cratonic sources during the Proterozoic to the earliest Phanerozoic. Typical tonalites and granodiorites that contain zircons with evolved Hf isotopic compositions formed upon incorporating (meta)sedimentary materials into calc-alkaline metaluminous magmas. The evolved Hf isotope ratios of zircons in the subduction related plutonic rocks strongly reflect the Hf isotopic character of the metasedimentary contaminant, even though the linked differentiation and growth of the Famatinian arc crust was driven by ascending and evolving mantle magmas. Geochronology and Hf isotope systematics in plutonic zircons allow us understanding the petrogenesis of igneous series and the provenance of magma sources. However, these data could be inadequate for computing model ages and supporting models of crustal evolution.

  19. Systematic review automation technologies

    Science.gov (United States)

    2014-01-01

    Systematic reviews, a cornerstone of evidence-based medicine, are not produced quickly enough to support clinical practice. The cost of production, availability of the requisite expertise and timeliness are often quoted as major contributors for the delay. This detailed survey of the state of the art of information systems designed to support or automate individual tasks in the systematic review, and in particular systematic reviews of randomized controlled clinical trials, reveals trends that see the convergence of several parallel research projects. We surveyed literature describing informatics systems that support or automate the processes of systematic review or each of the tasks of the systematic review. Several projects focus on automating, simplifying and/or streamlining specific tasks of the systematic review. Some tasks are already fully automated while others are still largely manual. In this review, we describe each task and the effect that its automation would have on the entire systematic review process, summarize the existing information system support for each task, and highlight where further research is needed for realizing automation for the task. Integration of the systems that automate systematic review tasks may lead to a revised systematic review workflow. We envisage the optimized workflow will lead to system in which each systematic review is described as a computer program that automatically retrieves relevant trials, appraises them, extracts and synthesizes data, evaluates the risk of bias, performs meta-analysis calculations, and produces a report in real time. PMID:25005128

  20. Geochemical and stable isotopic constraints on the generation and passive treatment of acidic, Fe-SO4 rich waters.

    Science.gov (United States)

    Matthies, Romy; Aplin, Andrew C; Boyce, Adrian J; Jarvis, Adam P

    2012-03-15

    Reducing and Alkalinity Producing Systems (RAPS) remediate net-acidic metalliferous mine drainage by creating anoxic conditions in which bacterial sulfate reduction (BSR) raises alkalinity and drives the precipitation of iron and other chalcophilic elements as sulfides. We report chemical and stable isotopic data from a study monitoring the biogeochemical processes involved in the generation of mine waters and their remediation by two RAPS. Sulfur isotopes show that sulfate in all mine waters has a common source (pyrite oxidation), whilst oxygen isotopes show that oxidation of pyritic sulfur is mediated by Fe(III)(aq). The isotopic composition of dissolved sulfide, combined with the sulfur and oxygen isotopic composition of sulfate in RAPS effluents, proves BSR and details its dual isotope systematics. The occurrence and isotopic composition of solid phase iron sulfides indicate the removal of reduced sulfur within the RAPS, with significant amounts of elemental sulfur indicating reoxidation steps. However, only 0 to 9% of solid phase iron occurs as Fe sulfides, with approximately 70% of the removed iron occurs as Fe(III) (hydr)oxides. Some of the (hydr)oxide is supplied to the wetland as solids and is simply filtered by the wetland substrate, playing no role in alkalinity generation or proton removal. However, the majority of iron is supplied as dissolved Fe(II), indicating that acid generating oxidation and hydrolysis reactions dominate iron removal. The overall contribution of BSR to the sulfur geochemistry in the RAPS is limited and sulfate retention is dominated by sulfate precipitation, comparable to aerobic treatment systems, and show that the proton acidity resulting from iron oxidation and hydrolysis must be subsequently neutralised by calcite dissolution and/or BSR deeper in the RAPS sediments. BSR is not as important as previously thought for metal removal in RAPS. The results have practical consequences for the design, treatment performance and long

  1. Cd isotope fractionation during sulfide mineral weathering in the Fule Zn-Pb-Cd deposit, Yunnan Province, Southwest China.

    Science.gov (United States)

    Zhu, Chuanwei; Wen, Hanjie; Zhang, Yuxu; Yin, Runsheng; Cloquet, Christophe

    2017-11-03

    Zinc (Zn)-Lead (Pb) deposits are generally rich in cadmium (Cd), and the weathering of sulfide minerals in such deposits results in large releases of Cd into the environment. From an environmental and public health standpoint, understanding Cd sources and cycling is critical to identifying potential hazards to humans. In this study, the Cd isotope compositions (expressed as δ114/110Cd) of secondary minerals such as anglesite (-0.57±0.03‰; 2S.D.), granular smithsonite (0.04±0.14‰; 2S.D.), layered smithsonite (0.15±0.40‰; 2S.D.), hydrozincite (0.26±0.01‰; 2S.D.) and clay minerals (-0.01±0.06‰; 2S.D.) from the Fule Zn-Pb-Cd deposit, Southwest China, are investigated to better understand the Cd sources and cycling in this area. Combined with our previous study (Zhu et al., 2017), the work herein elucidates the patterns of Cd isotopic fractionation during the formation processes of such secondary minerals and traces the weathering of these minerals into the ecosystem. The δ114/110Cd values of secondary minerals exhibit the following decreasing trend: hydrozincite>large granular smithsonite>small granular smithsonite>anglesite. Although different amounts of Cd were lost during the formation of equally sized samples, no or minor variations in Cd isotopic composition were observed. However, significant isotopic differences were observed between different size fractions. These results demonstrate that the particle size of secondary minerals and weathering products of sulfide significantly influence Cd isotope composition and fractionation during natural weathering. This systematic fractionation provides an initial foundation for the use of Cd isotopes as environmental tracers in ecosystems and in the global Cd isotope budget. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Spatially controlled Fe and Si isotope variations: an alternative view on the formation of the Torres del Paine pluton

    Science.gov (United States)

    Gajos, Norbert A.; Lundstrom, Craig C.; Taylor, Alexander H.

    2016-11-01

    We present new Fe and Si isotope ratio data for the Torres del Paine igneous complex in southern Chile. The multi-composition pluton consists of an approximately 1 km vertical exposure of homogenous granite overlying a contemporaneous 250-m-thick mafic gabbro suite. This first-of-its-kind spatially dependent Fe and Si isotope investigation of a convergent margin-related pluton aims to understand the nature of granite and silicic igneous rock formation. Results collected by MC-ICP-MS show a trend of increasing δ56Fe and δ30Si with increasing silica content as well as a systematic increase in δ56Fe away from the mafic base of the pluton. The marginal Torres del Paine granites have heavier Fe isotope signatures (δ56Fe = +0.25 ± 0.02 2se) compared to granites found in the interior pluton (δ56Fe = +0.17 ± 0.02 2se). Cerro Toro country rock values are isotopically light in both Fe and Si isotopic systems (δ56Fe = +0.05 ± 0.02 ‰; δ30Si = -0.38 ± 0.07 ‰). The variations in the Fe and Si isotopic data cannot be accounted for by local assimilation of the wall rocks, in situ fractional crystallization, late-stage fluid exsolution or some combination of these processes. Instead, we conclude that thermal diffusion or source magma variation is the most likely process producing Fe isotope ratio variations in the Torres del Paine pluton.

  3. Scale of human mobility in the southern Andes (Argentina and Chile): A new framework based on strontium isotopes.

    Science.gov (United States)

    Barberena, Ramiro; Durán, Víctor A; Novellino, Paula; Winocur, Diego; Benítez, Anahí; Tessone, Augusto; Quiroga, María N; Marsh, Erik J; Gasco, Alejandra; Cortegoso, Valeria; Lucero, Gustavo; Llano, Carina; Knudson, Kelly J

    2017-10-01

    The goal of this article is to assess the scale of human paleomobility and ecological complementarity between the lowlands and highlands in the southern Andes during the last 2,300 years. By providing isotope results for human bone and teeth samples, we assess a hypothesis of "high residential mobility" suggested on the basis of oxygen isotopes from human remains. We develop an isotopic assessment of human mobility in a mountain landscape combining strontium and oxygen isotopes. We analyze bone and teeth samples as an approach to life-history changes in spatial residence. Human samples from the main geological units and periods within the last two millennia are selected. We present a framework for the analysis of bioavailable strontium based on the combination of the geological data with isotope results for rodent samples. The 87 Sr/ 86 Sr values from human samples indicate residential stability within geological regions along life history. When comparing strontium and oxygen values for the same human samples, we record a divergent pattern: while δ 18 O values for samples from distant regions overlap widely, there are important differences in 87 Sr/ 86 Sr values. Despite the large socio-economic changes recorded, 87 Sr/ 86 Sr values indicate a persisting scenario of low systematic mobility between the different geological regions. Our results suggest that strontium isotope values provide the most germane means to track patterns of human occupation of distinct regions in complex geological landscapes, offering a much higher spatial resolution than oxygen isotopes in the southern Andes. © 2017 Wiley Periodicals, Inc.

  4. Nitrogen isotopes in bulk marine sediment: linking seafloor observations with subseafloor records

    Directory of Open Access Journals (Sweden)

    J.-E. Tesdal

    2013-01-01

    Full Text Available The stable isotopes of nitrogen offer a unique perspective on changes in the nitrogen cycle, past and present. However, the presence of multiple forms of nitrogen in marine sediments can complicate the interpretation of bulk nitrogen isotope measurements. Although the large-scale global patterns of seafloor δ15N have been shown to match process-based expectations, small-scale heterogeneity on the seafloor, or alterations of isotopic signals during translation into the subseafloor record, could obscure the primary signals. Here, a public database of nitrogen isotope measurements is described, including both seafloor and subseafloor sediment samples ranging in age from modern to the Pliocene, and used to assess these uncertainties. In general, good agreement is observed between neighbouring seafloor sites within a 100 km radius, with 85% showing differences of < 1‰. There is also a good correlation between the δ15N of the shallowest (< 5 ka subseafloor sediments and neighbouring seafloor sites within a 100 km radius (R2 = 0.83, which suggests a reliable translation of sediments into the buried sediment record. Meanwhile, gradual δ15N decreases over multiple glacial–interglacial cycles appear to reflect post-depositional alteration in records from the deep sea (below 2000 m. We suggest a simple conceptual model to explain these 100-kyr-timescale changes in well-oxygenated, slowly accumulating sediments, which calls on differential loss rates for pools of organic N with different δ15N. We conclude that bulk sedimentary nitrogen isotope records are reliable monitors of past changes in the marine nitrogen cycle at most locations, and could be further improved with a better understanding of systematic post-depositional alteration. Furthermore, geochemical or environmental criteria should be developed in order to effectively identify problematic locations and to account for

  5. The impact of the intruder orbitals on the structure of neutron-rich Ag isotopes

    Directory of Open Access Journals (Sweden)

    Y.H. Kim

    2017-09-01

    Full Text Available The low-lying high-spin yrast band structure of neutron-rich 113,118–121Ag has been established for the first time using prompt γ-ray spectroscopy of isotopically identified fission fragments produced in the 9Be(238U, fγ fusion- and transfer-induced fission processes. The newly obtained level energies follow the systematics of the neighboring isotopes. The sequences of levels exhibit an energy inheritance from states in the corresponding Cd core. A striking constancy of a large signature splitting in odd-A Ag throughout the long chain of isotopes with 50isotopes, which are indications of triaxiality, were evidenced. These observed features were reproduced by large-scale shell-model calculations with a spherical basis for the first time in the Ag isotopic chain, revealing microscopically their complex nature with severely broken seniority ordering. The essential features of the observed signature splitting were further examined in the light of simplified, two-orbital shell-model calculations including only two intruder orbitals πg9/2 and νh11/2 from two consecutive shells above Z=50 and N=82 for protons and neutrons respectively, resulting in the πg9/2−3×νh11/2m configurations. The newly established bands were understood as fairly pure, built mainly on unique-parity intruder configurations and coupled to the basic states of the Cd core.

  6. Stable isotope composition of atmospheric carbon monoxide. A modelling study

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, Sergey S.

    2014-11-01

    This study aims at an improved understanding of the stable carbon and oxygen isotope composition of the carbon monoxide (CO) in the global atmosphere by means of numerical simulations. At first, a new kinetic chemistry tagging technique for the most complete parameterisation of isotope effects has been introduced into the Modular Earth Submodel System (MESSy) framework. Incorporated into the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model, an explicit treatment of the isotope effects on the global scale is now possible. The expanded model system has been applied to simulate the chemical system containing up to five isotopologues of all carbon- and oxygen-bearing species, which ultimately determine the δ{sup 13}C, δ{sup 18}O and Δ{sup 17}O isotopic signatures of atmospheric CO. As model input, a new stable isotope-inclusive emission inventory for the relevant trace gases has been compiled. The uncertainties of the emission estimates and of the resulting simulated mixing and isotope ratios have been analysed. The simulated CO mixing and stable isotope ratios have been compared to in-situ measurements from ground-based observatories and from the civil-aircraft-mounted CARIBIC-1 measurement platform. The systematically underestimated {sup 13}CO/{sup 12}CO ratios of earlier, simplified modelling studies can now be partly explained. The EMAC simulations do not support the inferences of those studies, which suggest for CO a reduced input of the highly depleted in {sup 13}C methane oxidation source. In particular, a high average yield of 0.94 CO per reacted methane (CH{sub 4}) molecule is simulated in the troposphere, to a large extent due to the competition between the deposition and convective transport processes affecting the CH{sub 4} to CO reaction chain intermediates. None of the other factors, assumed or disregarded in previous studies, however hypothesised to have the potential in enriching tropospheric CO in {sup 13}C, were found significant

  7. Matching isotopic distributions from metabolically labeled samples.

    Science.gov (United States)

    McIlwain, Sean; Page, David; Huttlin, Edward L; Sussman, Michael R

    2008-07-01

    In recent years stable isotopic labeling has become a standard approach for quantitative proteomic analyses. Among the many available isotopic labeling strategies, metabolic labeling is attractive for the excellent internal control it provides. However, analysis of data from metabolic labeling experiments can be complicated because the spacing between labeled and unlabeled forms of each peptide depends on its sequence, and is thus variable from analyte to analyte. As a result, one generally needs to know the sequence of a peptide to identify its matching isotopic distributions in an automated fashion. In some experimental situations it would be necessary or desirable to match pairs of labeled and unlabeled peaks from peptides of unknown sequence. This article addresses this largely overlooked problem in the analysis of quantitative mass spectrometry data by presenting an algorithm that not only identifies isotopic distributions within a mass spectrum, but also annotates matches between natural abundance light isotopic distributions and their metabolically labeled counterparts. This algorithm is designed in two stages: first we annotate the isotopic peaks using a modified version of the IDM algorithm described last year; then we use a probabilistic classifier that is supplemented by dynamic programming to find the metabolically labeled matched isotopic pairs. Such a method is needed for high-throughput quantitative proteomic metabolomic experiments measured via mass spectrometry. The primary result of this article is that the dynamic programming approach performs well given perfect isotopic distribution annotations. Our algorithm achieves a true positive rate of 99% and a false positive rate of 1% using perfect isotopic distribution annotations. When the isotopic distributions are annotated given 'expert' selected peaks, the same algorithm gets a true positive rate of 77% and a false positive rate of 1%. Finally, when annotating using machine selected peaks, which

  8. Iron isotope biogeochemistry of Neoproterozoic marine shales

    Science.gov (United States)

    Kunzmann, Marcus; Gibson, Timothy M.; Halverson, Galen P.; Hodgskiss, Malcolm S. W.; Bui, Thi Hao; Carozza, David A.; Sperling, Erik A.; Poirier, André; Cox, Grant M.; Wing, Boswell A.

    2017-07-01

    Iron isotopes have been widely applied to investigate the redox evolution of Earth's surface environments. However, it is still unclear whether iron cycling in the water column or during diagenesis represents the major control on the iron isotope composition of sediments and sedimentary rocks. Interpretation of isotopic data in terms of oceanic redox conditions is only possible if water column processes dominate the isotopic composition, whereas redox interpretations are less straightforward if diagenetic iron cycling controls the isotopic composition. In the latter scenario, iron isotope data is more directly related to microbial processes such as dissimilatory iron reduction. Here we present bulk rock iron isotope data from late Proterozoic marine shales from Svalbard, northwestern Canada, and Siberia, to better understand the controls on iron isotope fractionation in late Proterozoic marine environments. Bulk shales span a δ 56Fe range from -0.45 ‰ to +1.04 ‰ . Although δ 56Fe values show significant variation within individual stratigraphic units, their mean value is closer to that of bulk crust and hydrothermal iron in samples post-dating the ca. 717-660 Ma Sturtian glaciation compared to older samples. After correcting for the highly reactive iron content in our samples based on iron speciation data, more than 90% of the calculated δ 56Fe compositions of highly reactive iron falls in the range from ca. -0.8 ‰ to +3 ‰ . An isotope mass-balance model indicates that diagenetic iron cycling can only change the isotopic composition of highly reactive iron by water column processes, namely the degree of oxidation of the ferrous seawater iron reservoir, control the isotopic composition of highly reactive iron. Considering a long-term decrease in the isotopic composition of the iron source to the dissolved seawater Fe(II) reservoir to be unlikely, we offer two possible explanations for the Neoproterozoic δ 56Fe trend. First, a decreasing supply of Fe

  9. Stable isotopes in Lithuanian bioarcheological material

    Science.gov (United States)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

    Investigation of bioarcheological material of ancient human populations allows us to understand the subsistence behavior associated with various adaptations to the environment. Feeding habits are essential to the survival and growth of ancient populations. Stable isotope analysis is accepted tool in paleodiet (Schutkowski et al, 1999) and paleoenvironmental (Zernitskaya et al, 2014) studies. However, stable isotopes can be useful not only in investigating human feeding habits but also in describing social and cultural structure of the past populations (Le Huray and Schutkowski, 2005). Only few stable isotope investigations have been performed before in Lithuanian region suggesting a quite uniform diet between males and females and protein intake from freshwater fish and animal protein. Previously, stable isotope analysis has only been used to study a Stone Age population however, more recently studies have been conducted on Iron Age and Late medieval samples (Jacobs et al, 2009). Anyway, there was a need for more precise examination. Stable isotope analysis were performed on human bone collagen and apatite samples in this study. Data represented various ages (from 5-7th cent. to 18th cent.). Stable carbon and nitrogen isotope analysis on medieval populations indicated that individuals in studied sites in Lithuania were almost exclusively consuming C3 plants, C3 fed terrestrial animals, and some freshwater resources. Current investigation demonstrated social differences between elites and country people and is promising in paleodietary and daily life reconstruction. Acknowledgement I thank prof. dr. G. Grupe, Director of the Anthropological and Palaeoanatomical State Collection in Munich for providing the opportunity to work in her laboratory. The part of this work was funded by DAAD. Antanaitis-Jacobs, Indre, et al. "Diet in early Lithuanian prehistory and the new stable isotope evidence." Archaeologia Baltica 12 (2009): 12-30. Le Huray, Jonathan D., and Holger

  10. Carbon Isotopes in an Earth System Model

    Science.gov (United States)

    Cuntz, M.; Reick, C. H.; Maier-Reimer, E.; Heimann, M.; Scholze, M.; Naegler, T.

    2009-04-01

    We present first calculations of the carbon isotopic composition of carbon dioxide in the Earth System Model (ESM) COSMOS. Earth System models consist of coupled models of the ocean, the atmosphere, the land surface, the biosphere (marine and terrestrial, plants and soils), and the cryosphere (snow and ice). In COSMOS from the Max Planck Institute for Meteorology, Hamburg, Germany, these components are the model of the atmospheric circulation ECHAM, the physical ocean model MPI-OM, the land surface parameterisation JSBACH and the oceanic carbon cycle model HAMOCC. The ESM COSMOS therefore calculates its own climate and CO2 concentrations during the diel course with a few degrees resolution, driven only by solar activity and human perturbations. The new model version now computes the multiple fractionation processes occurring during uptake of CO2 from the atmosphere by the terrestrial and marine biosphere. The model then redistributes the isotopic compositions in the land and ocean biospheres, including respiration, phenology, fire, land-use change and carbon export. This means that it includes a full isotopic carbon cycle, in the atmosphere, the ocean and on land. The model calculates not only the stable carbon isotope signatures but also radiocarbon activities in the Earth System. It will include in future the radiocarbon perturbation due to nuclear bomb tests. We compare first results of the ESM with other global estimates of terrestrial discrimination. We also compare predicted zonal and seasonal variations of isotope ratios in atmospheric CO2 with measurements from the GLOBALVIEW flask network. The stable and radioactive carbon isotopes are excellent tests for the overall model performance but also for individual model components. For example radiocarbon will be used to test stratosphere-troposphere exchange, ocean circulation and air-sea gas exchange. The isotope-enabled model can be used in future for example to predict carbon isotope ratios of terrestrial

  11. Tungsten Stable Isotope Compositions of Ferromanganese Crusts

    Science.gov (United States)

    Abraham, K.; Barling, J.; Hein, J. R.; Schauble, E. A.; Halliday, A. N.

    2014-12-01

    We report the first accurate and precise data for mass-dependent fractionation of tungsten (W) stable isotopes, using a double spike technique and MC-ICPMS. Results are expressed relative to the NIST 3136 W isotope standard as per mil deviations in 186W/184W (δ186W). Although heavy element mass-dependent fractionations are expected to be small, Tl and U both display significant low temperature isotopic fractionations. Theoretical calculations indicate that W nuclear volume isotopic effects should be smaller than mass-dependent fractionations at low temperatures. Hydrogenetic ferromanganese (Fe-Mn) crusts precipitate directly from seawater and have been used as paleoceanographic recorders of temporal changes in seawater chemistry. Crusts are strongly enriched in W and other metals, and are a promising medium for exploring W isotopic variability. Tungsten has a relatively long residence time in seawater of ~61,000 years, mainly as the tungstate ion (WO42-). Water depth profiles show conservative behaviour. During adsorption on Fe-Mn crusts, W species form inner-sphere complexes in the hexavalent (W6+) state. The major host phase is thought to be Mn oxides and the lighter W isotope is expected to be absorbed preferentially. Surface scrapings of 13 globally distributed hydrogenetic Fe-Mn crusts display δ186W from -0.08 to -0.22‰ (±0.03‰, 2sd). A trend toward lighter W isotope composition exists with increasing water depth (~1500 to ~5200m) and W concentration. One hydrothermal Mn-oxide sample is anomalously light and Mn nodules are both heavy and light relative to Fe-Mn crusts. Tungsten speciation depends on concentration, pH, and time in solution and is not well understood because of the extremely slow kinetics of the reactions. In addition, speciation of aqueous and/or adsorbed species might be sensitive to pressure, showing similar thermodynamic stability but different effective volumes. Thus, W stable isotopes might be used as a water-depth barometer in

  12. Iron Isotope Constraints on Planetesimal Core Formation

    Science.gov (United States)

    Jordan, M.; Young, E. D.

    2016-12-01

    The prevalence of iron in both planetary cores and silicate mantles renders the element a valuable tool for understanding core formation. Magmatic iron meteorites exhibit an enrichment in 57Fe/54Fe relative to chondrites and HED meteorites. This is suggestive of heavy Fe partitioning into the cores of differentiated bodies. If iron isotope fractionation accompanies core formation, we can elucidate details about the history of accretion for planetary bodies as well as their compositions and relative core sizes. The equilibrium 57Fe/54Fe between metal and silicate is necessary for understanding observed iron isotope compositions and placing constraints on core formation. We measure this fractionation in two Aubrite meteorites, Norton County and Mount Egerton, which have known temperatures of equilibration and equilibrated silicon isotopes. Iron was purified using ion-exchange chromatography. Data were collected on a ThermoFinnigan NeptuneTM multiple-collector inductively coupled plasma-source mass spectrometer (MC-ICP-MS) run in wet plasma mode. The measured fractionation Δ57Femetal-silicate is 0.08‰ ± 0.039 (2 SE) for Norton County and 0.09‰ ± 0.019 (2 SE) for Mount Egerton, indicating that the heavy isotopes of Fe partition into the metallic phase. These rocks are in isotopic equilibrium at a temperature of 1130 K and 1200 K ± 80 K, respectively. The concentration of the heavy isotopes of iron in the metallic phase is consistent with recent experimental studies. Using our measured metal-silicate Fe isotope fractionation and the resulting temperature calibration, while taking into account impurities in the metallic phase and temperatures of equilibration, determine that core formation could explain the observed difference between magmatic iron meteorites and chondrites if parent bodies have small cores. In order to verify that Rayleigh distillation during fractional crystallization was not a cause of iron isotope fractionation in iron meteorites, we measured

  13. CERN to start producing medical isotopes

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    A promising project that was hailed at the ICTR-PHE 2012 medical conference (see Bulletin issues 10-11/2012 and 12-13/2012) has seen the light of day at CERN. The project, known by the name of MEDICIS, will make it possible to produce a large variety of radioactive isotopes for medical research.   This image of a brain, superimposed on a drawing by Leonardo da Vinci, was taken by a PET scanner after injecting a molecule containing a positron-emitting isotope. CERN-MEDICIS will produce new isotopes for imaging which will be able to show up cancerous tissues and destroy them by emitting local radiation as the isotopes decay. In the United States, a new radium-based drug which targets bone metastases is about to go on the market. Radium, which can be brought to bear at the cell level, is a potent weapon in the fight against certain types of cancer, and is opening the way to a new form of medicine. This is the direction that CERN has decided to follow through the CERN-MEDICIS* (Medical Isotopes...

  14. Tin isotope fractionation in terrestrial cassiterites

    Energy Technology Data Exchange (ETDEWEB)

    McNaughton, N.J. (Univ. of Western Australia, Nedlands (Australia)); Rosman, K.J.R. (Curtin Univ. of Technology, Bentley (Australia))

    1991-02-01

    The isotopic composition of tin has been measured in a range of cassiterites and pure reagents to assess the extent to which this element is isotopically fractionated in natural processes. Only two samples showed evidence of isotopic fractionation, and it is concluded that natural Sn isotope fractionation is small and uncommon. This feature reflects the world dominance of Sn-oxide ores Sn-sulfide ores, and the highly efficient processes of Sn dissolution and precipitation which negate equilibrium and kinetic fractionation of Sn isotopes, respectively. The two samples which show slight fractionation are a highly purified and cassiterite from the Archaean Greenbushes pegmatite, Western Australia. The latter Sn is 0.15{per thousand} per mass unit heavier than the authors laboratory standard, whereas the former is 0.12{per thousand} per mass unit lighter. Although the cassiterite fractionation is considered to result from natural geological processes, the fractionation of purified Sn may be either natural or relate to the purification process, the fractionation of this magnitude has a negligible effect on the current best estimate of the atomic weight of Sn, but it does place a lower limit on its associated accuracy.

  15. Stable isotope analysis of dynamic lipidomics.

    Science.gov (United States)

    Brandsma, Joost; Bailey, Andrew P; Koster, Grielof; Gould, Alex P; Postle, Anthony D

    2017-08-01

    Metabolic pathway flux is a fundamental element of biological activity, which can be quantified using a variety of mass spectrometric techniques to monitor incorporation of stable isotope-labelled substrates into metabolic products. This article contrasts developments in electrospray ionisation mass spectrometry (ESI-MS) for the measurement of lipid metabolism with more established gas chromatography mass spectrometry and isotope ratio mass spectrometry methodologies. ESI-MS combined with diagnostic tandem MS/MS scans permits the sensitive and specific analysis of stable isotope-labelled substrates into intact lipid molecular species without the requirement for lipid hydrolysis and derivatisation. Such dynamic lipidomic methodologies using non-toxic stable isotopes can be readily applied to quantify lipid metabolic fluxes in clinical and metabolic studies in vivo. However, a significant current limitation is the absence of appropriate software to generate kinetic models of substrate incorporation into multiple products in the time domain. Finally, we discuss the future potential of stable isotope-mass spectrometry imaging to quantify the location as well as the extent of lipid synthesis. This article is part of a Special Issue entitled: BBALIP_Lipidomics Opinion Articles edited by Sepp Kohlwein. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Second international conference on isotopes. Conference proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, C.J. [ed.

    1997-10-01

    The Second International Conference on Isotopes (2ICI) was hosted by the Australian Nuclear Association in Sydney, NSW, Australia. The Theme of the Second Conference: Isotopes for Industry, Health and a Better Environment recognizes that isotopes have been used in these fields successfully for many years and offer prospects for increasing use in the future. The worldwide interest in the use of research reactors and accelerators and in applications of stable and radioactive isotopes, isotopic techniques and radiation in industry, agriculture, medicine, environmental studies and research in general, was considered. Other radiation issues including radiation protection and safety were also addressed. International and national overviews and subject reviews invited from leading experts were included to introduce the program of technical sessions. The invited papers were supported by contributions accepted from participants for oral and poster presentation. A Technical Exhibition was held in association with the Conference. This volume contains the foreword, technical program, the author index and of the papers (1-60) presented at the conference.

  17. Stable Isotope Spectroscopy for Diagnostic Medicine

    Science.gov (United States)

    Murnick, D. E.

    2000-06-01

    Isotopic tracers have been used in medical research for more than fifty years. Radioactive isotopes have been most used because of the high detection efficiencies possible. With increased awareness of the effects of low level radiation and radioactive waste management problems, the need for safe non radioactive tracers has become apparent. Rare stable isotopes of biologically active elements can be used for metabolic and pharmacokinetic studies provided that both sufficient detection sensitivity can be achieved and reliable cost effective instruments can be developed. High resolution optical spectroscopic methods which can determine isotopic ratios with high precision and accuracy are viable for research and clinical use. The study of 13C/12C ratios in CO2 for breath test diagnostics will be described in detail. Using the laser optogalvonic effect with isotopic lasers a specific medical diagnostic for h-pylori infection, has recently received FDA approval. Opportunities exist to study D/H ratios in water and 18O/16O ratios in CO2 and water for basic metabolism diagnostics and 15N/14N ratios in urine for liver function and related studies.

  18. Carbon isotopes in mollusk shell carbonates

    Science.gov (United States)

    McConnaughey, Ted A.; Gillikin, David Paul

    2008-10-01

    Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod shell carbonates. Land snails construct their shells mainly from respired CO2, and shell δ13C reflects the local mix of C3 and C4 plants consumed. Shell δ13C is typically >10‰ heavier than diet, probably because respiratory gas exchange discards CO2, and retains the isotopically heavier HCO3 -. Respired CO2 contributes less to the shells of aquatic mollusks, because CO2/O2 ratios are usually higher in water than in air, leading to more replacement of respired CO2 by environmental CO2. Fluid exchange with the environment also brings additional dissolved inorganic carbon (DIC) into the calcification site. Shell δ13C is typically a few ‰ lower than ambient DIC, and often decreases with age. Shell δ13C retains clues about processes such as ecosystem metabolism and estuarine mixing. Ca2+ ATPase-based models of calcification physiology developed for corals and algae likely apply to mollusks, too, but lower pH and carbonic anhydrase at the calcification site probably suppress kinetic isotope effects. Carbon isotopes in biogenic carbonates are clearly complex, but cautious interpretation can provide a wealth of information, especially after vital effects are better understood.

  19. Fusion and the Discovery of Isotopes

    Science.gov (United States)

    Thoennessen, M.

    2017-11-01

    Heavy-ion fusion-evaporation has been the most productive method to form and identify new isotopes. Of the presently known over 3200 isotopes, almost 25% were discovered with heavy-ion induced reactions. Since the development of the first heavy-ion beam at Berkeley in 1950 most of the nuclides on the neutron-deficient side of the line of stability and all isotopes of the superheavy elements were discovered utilizing fusion reactions. In addition, some isotopes were first produced in heavy-ion transfer, charge-exchange, incomplete fusion or deep inelastic reactions. The discovery of isotopes relies on new advances in accelerator and detector technology. The continuous development of pioneering and innovative separation and detection techniques have pushed the limit towards ‒ and in many cases beyond ‒ the proton-dripline. A review of the discovery of neutron-deficient and super-heavy nuclides in heavy-ion induced reactions as well as an outlook for the discovery potential in the future is presented.

  20. A Hydrogen and He Isotope Nanoprobe

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, Barney L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Van Deusen, Stuart B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Materials that incorporate hydrogen and helium isotopes are of great interest at Sandia and throughout the NNSA and DOE. The Ion Beam Lab at SNL-NM has invented techniques using micron to mm-size MeV ion beams to recoil these light isotopes (Elastic Recoil Detection or ERD) that can very accurately make such measurements. However, there are many measurements that would benefit NW and DOE that require much better resolution, such as the distribution of H isotopes (and 3He) in individual grains of materials relevant to TPBARs, H and He-embrittlement of weapon components important to Tritium Sustainment Programs, issues with GTSs, batteries… Higher resolution would also benefit the field of materials science in general. To address these and many other issues, nm-scale lateral resolution is required. This LDRD demonstrated that neutral H atoms could be recoiled through a thin film by 70 keV electrons and detected with a Channeltron electron multiplier (CEM). The electrons were steered away from the CEM by strong permanent magnets. This proved the feasibility that the high energy electrons from a transmissionelectron- microscope-TEM can potentially be used to recoil and subsequently detect (e-ERD), quantify and map the concentration of H and He isotopes with nm resolution. This discovery could lead to a TEM-based H/He-isotope nanoprobe with 1000x higher resolution than currently available.

  1. Perspectives on land snails - sampling strategies for isotopic analyses

    Science.gov (United States)

    Kwiecien, Ola; Kalinowski, Annika; Kamp, Jessica; Pellmann, Anna

    2017-04-01

    ) produces replicable results. This reproducibility enables not only sequential testing of isotopic changes in shells exposed to artificially elevated temperatures, but also systematic assessment of different cleaning methods. Goodfriend, 1992. The use of land snail shells in paleoenvironmental reconstruction, EPSL 11, 655-685

  2. Combining Solvent Isotope Effects with Substrate Isotope Effects in Mechanistic Studies of Alcohol and Amine Oxidation by Enzymes*

    Science.gov (United States)

    Fitzpatrick, Paul F.

    2014-01-01

    Oxidation of alcohols and amines is catalyzed by multiple families of flavin-and pyridine nucleotide-dependent enzymes. Measurement of solvent isotope effects provides a unique mechanistic probe of the timing of the cleavage of the OH and NH bonds, necessary information for a complete description of the catalytic mechanism. The inherent ambiguities in interpretation of solvent isotope effects can be significantly decreased if isotope effects arising from isotopically labeled substrates are measured in combination with solvent isotope effects. The application of combined solvent and substrate (mainly deuterium) isotope effects to multiple enzymes is described here to illustrate the range of mechanistic insights that such an approach can provide. PMID:25448013

  3. Water Metabolism of Walruses by Isotope Dilution

    DEFF Research Database (Denmark)

    Acquarone, M.; Born, E. W.; Chwalibog, A.

    In August 2000, the hydrogen isotope dilution method was used on 7 adult male Atlantic walruses (Odobenus rosmarus rosmarus) (weight: 1197±148 kg, mean±SD, range 1013-1508 kg) at a terrestrial haul-out in Northeastern Greenland to determine their body water pool sizes and body water turnover rates....... During immobilization by use of etorphine HCl (reversed with diprenorphine HCl), a first blood sample was taken to measure background isotope levels. The animals were then enriched with deuterium oxide by infusion into the epidural vein. During recovery, while the animals were still on the beach, blood...... was sampled via an epidural catheter, at regular intervals, for up to seven hours after the initial enrichment to assess isotope equilibration in the body water pools. Five individuals returned to the haul-out after feeding trips of varying duration (158±86 hr, 44-287 hr) where they were immobilized again...

  4. Laser spectroscopy of neutron deficient Sn isotopes

    CERN Multimedia

    We propose to study the ground state properties of neutron-deficient Sn isotopes towards the doubly-magic nucleus $^{100}$Sn. Nuclear spins, changes in the rms charge radii and electromagnetic moments of $^{101-121}$Sn will be measured by laser spectroscopy using the CRIS experimental beam line. These ground-state properties will help to clarify the evolution of nuclear structure properties approaching the $\\textit{N = Z =}$ 50 shell closures. The Sn isotopic chain is currently the frontier for the application of state-of-the-art ab-initio calculations. Our knowledge of the nuclear structure of the Sn isotopes will set a benchmark for the advances of many-body methods, and will provide an important test for modern descriptions of the nuclear force.

  5. Stable isotope dilution assays in mycotoxin analysis.

    Science.gov (United States)

    Rychlik, Michael; Asam, Stefan

    2008-01-01

    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis.

  6. Strontium isotope stratigraphy of the Pelotas Basin

    Energy Technology Data Exchange (ETDEWEB)

    Zerfass, Geise de Santana dos Anjos, E-mail: geise.zerfass@petrobras.com.br [Petroleo Brasileiro S.A. (PETROBRAS/CENPES/PDGEO/BPA), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas e Desenvolvimento Leopoldo Americo Miguez de Mello; Chemale Junior, Farid, E-mail: fchemale@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Instituto de Geociencias; Moura, Candido Augusto Veloso, E-mail: candido@ufpa.br [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Centro de Geociencias. Dept. de Geoquimica e Petrologia; Costa, Karen Badaraco, E-mail: karen.costa@usp.br [Instituto Oceanografico, Sao Paulo, SP (Brazil); Kawashita, Koji, E-mail: koji@usp.br [Unversidade de Sao Paulo (USP), SP (Brazil). Centro de Pesquisas Geocronologicas

    2014-07-01

    Strontium isotope data were obtained from foraminifera shells of the Pelotas Basin Tertiary deposits to facilitate the refinement of the chronostratigraphic framework of this section. This represents the first approach to the acquisition of numerical ages for these strata. Strontium isotope stratigraphy allowed the identification of eight depositional hiatuses in the Eocene-Pliocene section, here classified as disconformities and a condensed section. The reconnaissance of depositional gaps based on confident age assignments represents an important advance considering the remarkably low chronostratigraphic resolution in the Cenozoic section of the Pelotas Basin. The recognition of hiatuses that match hiatuses is based on biostratigraphic data, as well as on global events. Furthermore, a substantial increase in the sedimentation rate of the upper Miocene section was identified. Paleotemperature and productivity trends were identified based on oxygen and carbon isotope data from the Oligocene-Miocene section, which are coherent with worldwide events, indicating the environmental conditions during sedimentation. (author)

  7. Stable Oxygen-18 and Deuterium Isotopes

    DEFF Research Database (Denmark)

    Müller, Sascha

    link the observed seasonal regression/transgression pattern to the inland recharge cycle, which is expressed in hydraulic head configuration and submarine groundwater discharge rates at the fieldsite. Nonetheless, those observed dynamics could not be simulated due to numerical limitations. By the use...... the Skjern River catchment, Denmark. The presented applications focused on studying the isotopic 'input signal' to the hydrosphere in the form of precipitation, the isotopic 'output signal' with its related dynamic processes at a coastal saltwater-freshwater interface (groundwater isotopes) and the temporal...... young age. Those results are in contrast to earlier age estimations from groundwater samples just beneath the stream. We therefore suggest the conceptualization of the hydrological conditions at this headwater catchment to be revised....

  8. Isotope analysis in the transmission electron microscope

    Science.gov (United States)

    Susi, Toma; Hofer, Christoph; Argentero, Giacomo; Leuthner, Gregor T.; Pennycook, Timothy J.; Mangler, Clemens; Meyer, Jannik C.; Kotakoski, Jani

    2016-10-01

    The Ångström-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either 12C or 13C and describe the process using a quantum mechanical model of lattice vibrations coupled with density functional theory simulations. We then test our spatial resolution in a mixed sample by ejecting individual atoms from nanoscale areas spanning an interface region that is far from atomically sharp, mapping the isotope concentration with a precision better than 20%. Although we use a scanning instrument, our method may be applicable to any atomic resolution transmission electron microscope and to other low-dimensional materials.

  9. Stable isotope dilution assays in mycotoxin analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rychlik, Michael; Asam, Stefan [Universitaet Muenchen, Lehrstuhl fuer Lebensmittelchemie der Technischen, Garching (Germany)

    2008-01-15

    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis. (orig.)

  10. Chromium isotope fractionation in ferruginous sediments

    Science.gov (United States)

    Bauer, Kohen W.; Gueguen, Bleuenn; Cole, Devon B.; Francois, Roger; Kallmeyer, Jens; Planavsky, Noah; Crowe, Sean A.

    2018-02-01

    Ferrous Fe is a potent reductant of Cr(VI), and while a number of laboratory studies have characterized Cr isotope fractionation associated with Cr(VI) reduction by ferrous iron, the expression of this fractionation in real-world ferrous Fe-rich environments remains unconstrained. Here we determine the isotope fractionation associated with Cr(VI) reduction in modern ferrous Fe-rich sediments obtained from the previously well studied Lake Matano, Indonesia. Whole core incubations demonstrate that reduction of Cr(VI) within ferruginous sediments provides a sink for Cr(VI) leading to Cr(VI) concentration gradients and diffusive Cr(VI) fluxes across the sediment water interface. As reduction proceeded, Cr(VI) remaining in the overlying lake water became progressively enriched in the heavy isotope (53Cr), increasing δ53Cr by 2.0 ± 0.1‰ at the end of the incubation. Rayleigh distillation modelling of the evolution of Cr isotope ratios and Cr(VI) concentrations in the overlying water yields an effective isotope fractionation of εeff = 1.1 ± 0.2‰ (53Cr/52Cr), whereas more detailed diagenetic modelling implies an intrinsic isotope fractionation of εint = 1.80 ± 0.04‰. Parallel slurry experiments performed using anoxic ferruginous sediment yield an intrinsic isotope fractionation of εint = 2.2 ± 0.1‰. These modelled isotope fractionations are corroborated by direct measurement of the δ53Cr composition on the upper 0.5 cm of Lake Matano sediment, revealing an isotopic offset from the lake water of Δ53Cr = 0.21-1.81‰. The data and models reveal that effective isotope fractionations depend on the depth at which Cr(VI) reduction takes place below the sediment water interface-the deeper the oxic non-reactive zone, the smaller the effective fractionation relative to the intrinsic fractionation. Based on the geochemistry of the sediment we suggest the electron donors responsible for reduction are a combination of dissolved Fe(II) and 0.5 M HCl extractable (solid

  11. Ca isotope fractionation on the moon

    Science.gov (United States)

    Russell, W. A.; Papanastassiou, D. A.; Tombrello, T. A.; Epstein, S.

    1977-01-01

    Ca has been measured in a lunar soil in order to establish the presence of isotopically mass-fractionated components. Ca was extracted by a series of water leaches after the soils were 'activated' by brief exposures to fluorine gas. The O2 obtained by this fluorination is found to have delta (O-18) of +21 per mil and to be, therefore, significantly mass-fractionated. Ca obtained in the leaches was analyzed using the double-spike technique. Very small Ca isotope fractionation is found in the leaches of this soil of up to 1 per mil per mass unit difference. The small Ca effects are in marked contrast to the measured delta (O-18) for the same sample and to large effects observed in many soils for oxygen, silicon, sulfur, and potassium. The data on Ca provide stringent constraints on models which attempt to explain the isotope mass-fractionation effects in lunar soils.

  12. Guideline on Isotope Dilution Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Gaffney, Amy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-05-19

    Isotope dilution mass spectrometry is used to determine the concentration of an element of interest in a bulk sample. It is a destructive analysis technique that is applicable to a wide range of analytes and bulk sample types. With this method, a known amount of a rare isotope, or ‘spike’, of the element of interest is added to a known amount of sample. The element of interest is chemically purified from the bulk sample, the isotope ratio of the spiked sample is measured by mass spectrometry, and the concentration of the element of interest is calculated from this result. This method is widely used, although a mass spectrometer required for this analysis may be fairly expensive.

  13. Isotope shift measurements on the D1 line in francium isotopes at TRIUMF

    Science.gov (United States)

    Collister, R.; Tandecki, M.; Gwinner, G.; Behr, J. A.; Pearson, M. R.; Gomez, E.; Aubin, S.; Zhang, J.; Orozco, L. A.

    2013-05-01

    Francium is the heaviest alkali and has no stable isotopes. The longest-lived among them, with half-lives from seconds to a few minutes, are now available in the new Francium Trapping Facility at TRIUMF, Canada, for future weak interaction studies. We present isotope shift measurements on the 7S1 / 2 --> 7P1 / 2 (D 1) transition on three isotopes, 206, 207 and 213 in a magneto-optical trap. The shifts are measured using a c.w. Ti:sapphire laser locked to a stabilized cavity at the mid-point between two hyperfine transitions of the reference isotope 209Fr. Scanning tunable microwave sidebands locate transitions in the other isotopes. In combination with the D 2 isotope shifts, analysis can provide a separation of the field shift, due to a changing nuclear charge radius, and specific mass shift, due to changing electron correlations, in these isotopes. Work supported by NSERC and NRC from Canada, NSF and DOE from USA, CONYACT from Mexico.

  14. Zinc isotope fractionation during magmatic differentiation and the isotopic composition of the bulk Earth

    Science.gov (United States)

    Chen, Heng; Savage, Paul S.; Teng, Fang-Zehn; Helz, Rosalind T.; Moynier, Frédéric

    2013-01-01

    he zinc stable isotope system has been successfully applied to many and varied fields in geochemistry, but to date it is still not completely clear how this isotope system is affected by igneous processes. In order to evaluate the potential application of Zn isotopes as a proxy for planetary differentiation and volatile history, it is important to constrain the magnitude of Zn isotopic fractionation induced by magmatic differentiation. In this study we present high-precision Zn isotope analyses of two sets of chemically diverse, cogenetic samples from Kilauea Iki lava lake, Hawaii, and Hekla volcano, Iceland, which both show clear evidence of having undergone variable and significant degrees of magmatic differentiation. The Kilauea Iki samples display small but resolvable variations in Zn isotope composition (0.26‰66Zn66Zn defined as the per mille deviation of a sample's 66Zn/64Zn compositional ratio from the JMC-Lyon standard), with the most differentiated lithologies exhibiting more positive δ66Zn values. This fractionation is likely a result of the crystallization of olivine and/or Fe–Ti oxides, which can both host Zn in their crystal structures. Samples from Hekla have a similar range of isotopic variation (0.22‰66Zn66Zn=0.28±0.05‰ (2s.d.).

  15. Tracing subducted sediment inputs to the Ryukyu arc-Okinawa Trough system: Evidence from thallium isotopes

    Science.gov (United States)

    Shu, Yunchao; Nielsen, Sune G.; Zeng, Zhigang; Shinjo, Ryuichi; Blusztajn, Jerzy; Wang, Xiaoyuan; Chen, Shuai

    2017-11-01

    Sediments are actively subducted in virtually every arc worldwide. However, quantifying their contributions to arc lavas and thereby establishing budgets of how sediments participate in slab-mantle interaction is challenging. In this contribution we use thallium (Tl) abundances and isotopic compositions of lavas from the Ryukyu arc (including south Kyushu) and its back-arc basin, Okinawa Trough, to investigate the influence of sediments from arc to back-arc. We also present extensive geochemical data for sediments and altered oceanic crust (AOC) outboard of the northern (DSDP Sites 296, 442B, 443 and 444) and central (DSDP Sites 294 and 295) part of the Ryukyu arc. The Tl isotopic compositions of sediments change systematically from lighter outboard of northern Ryukyu arc to heavier outboard of central Ryukyu arc. The feature reflects the dominance of terrigenous material and pelagic sedimentation outboard of the northern and central Ryukyu arc, respectively. Central and northern sections of Ryukyu arc and Okinawa Trough display larger range of Tl isotopic variation than southern section, which is consistent with more pelagic provenance for sediments outboard of central and northern Ryukyu arcs than that of expected sediments outboard of southern Ryukyu arc. Identical Tl, Sr, Nd and Pb isotope variations are found when comparing arc and back arc lavas, which indicates that sediments fluxes also account for the Tl isotopic variations in the Okinawa Trough lavas. Two-end-member mixing models of Tl with Pb, Sr and Nd isotopes require sediment inputs ofsediment end members predict very similar sediment fluxes when using Tl, Sr, Nd and Pb isotopes, which indicates that fractionation of these elements must have happened after mixing between mantle and sediments. This conclusion is corroborated by model calculations of mixing between sediment melts with fractionated Sr/Nd ratios and mantle wedge, which show that no arc lava plot on such mixing lines. Thus bulk sediment

  16. In-situ observations of the isotopic composition of methane at the Cabauw tall tower site

    Science.gov (United States)

    Röckmann, Thomas; Eyer, Simon; van der Veen, Carina; E Popa, Maria; Tuzson, Béla; Monteil, Guillaume; Houweling, Sander; Harris, Eliza; Brunner, Dominik; Fischer, Hubertus; Zazzeri, Giulia; Lowry, David; Nisbet, Euan G.; Brand, Willi A.; Necki, Jaroslav M.; Emmenegger, Lukas; Mohn, Joachim

    2017-04-01

    High precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS) based technique for in-situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw experimental site for atmospheric research (CESAR) in the Netherlands and performed in-situ, high-frequency (approx. hourly) measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of +0.05 ± 0.03 ‰ for δ13C-CH4 and -3.6 ± 0.4 ‰ for δD-CH4. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high precision and temporal resolution dataset does not only reveal the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site, but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget, when they are performed at multiple sites that are representative for the entire European

  17. In situ observations of the isotopic composition of methane at the Cabauw tall tower site

    Directory of Open Access Journals (Sweden)

    T. Röckmann

    2016-08-01

    Full Text Available High-precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS and a quantum cascade laser absorption spectroscopy (QCLAS-based technique for in situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw Experimental Site for Atmospheric Research (CESAR in the Netherlands and performed in situ, high-frequency (approx. hourly measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of (+0.25 ± 0.04 ‰ for δ13C and (−4.3 ± 0.4 ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high-precision and high-temporal-resolution dataset not only reveals the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget when they are performed at multiple sites that are representative for

  18. The molybdenum isotopic compositions of I-, S- and A-type granitic suites

    Science.gov (United States)

    Yang, Jie; Barling, Jane; Siebert, Christopher; Fietzke, Jan; Stephens, Ed; Halliday, Alex N.

    2017-05-01

    This study reports Mo isotopic compositions for fifty-two Palaeozoic granitic rocks with contrasting source affinities (A-, I- and S-type) from the Lachlan Fold Belt (LFB) and the New England Batholith (NEB), both in SE Australia, and three compositionally zoned plutons (Loch Doon, Criffell, and Fleet) located in the Southern Uplands of Scotland. The results show relatively large variations in δ98Mo for igneous rocks ranging from -1.73‰ to 0.59‰ with significant overlaps between different types. No relationships between δ98Mo and δ18O or ASI (Alumina Saturation Index) are observed, indicating that Mo isotopes do not clearly distinguish igneous vs. sedimentary source types. Instead, effects of igneous processes, source mixing, regional geology, as well as hydrothermal activity control the Mo isotope compositions in these granites. It is found that Mo is mainly accommodated in biotite and to a lesser extent in hornblende. Hornblende and Fe3+-rich minerals may preferentially incorporate light isotopes, as reflected by negative correlations between δ98Mo and K/Rb and [Fe2O3]. There is a positive correlation between initial 87Sr/86Sr and δ98Mo in I-type granitic rocks, reflecting the admixing of material from isotopically distinct sources. Granitic rocks from Scotland and Australia display strikingly similar curvilinear trends in δ98Mo vs. initial 87Sr/86Sr despite the differing regional geology. Localized hydrothermal effects can result in low δ98Mo in granite, as seen in three samples from Loch Doon and Criffell which have anomalously light δ98Mo of <-1‰. Based on this study, an estimate of δ98Mo = 0.14 ± 0.07‰ (95% s.e.) for the Phanerozoic upper crust is proposed. This is slightly heavier than basalts indicating an isotopically light lower crust and/or a systematic change to the crust resulting from subduction of isotopically light dehydrated slab and/or pelagic sediment over time.

  19. Technical note: Consistent calculation of aquatic gross production from oxygen triple isotope measurements

    Directory of Open Access Journals (Sweden)

    J. Kaiser

    2011-07-01

    Full Text Available Oxygen triple isotope measurements can be used to calculate aquatic gross oxygen production rates. Past studies have emphasised the appropriate definition of the 17O excess and often used an approximation to derive production rates from the 17O excess. Here, I show that the calculation can be phrased more consistently and without any approximations using the relative 17O/16O and 18O/16O isotope ratio differences (delta values directly. I call this the "dual delta method". The 17O excess is merely a mathematical construct and the derived production rate is independent of its definition, provided all calculations are performed with a consistent definition. I focus on the mixed layer, but also show how time series of triple isotope measurements below the mixed layer can be used to derive gross production.

    In the calculation of mixed layer productivity, I explicitly include isotopic fractionation during gas invasion and evasion, which requires the oxygen supersaturation s to be measured as well. I also suggest how bubble injection could be considered in the same mathematical framework. I distinguish between concentration steady state and isotopic steady state and show that only the latter needs to be assumed in the calculation. It is even possible to derive an estimate of the net production rate in the mixed layer that is independent of the assumption of concentration steady state.

    I review measurements of the parameters required for the calculation of gross production rates and show how their systematic uncertainties as well as the use of different published calculation methods can cause large variations in the production rates for the same underlying isotope ratios. In particular, the 17O excess of dissolved O2 in equilibrium with atmospheric O2 and the 17O excess of photosynthetic O2 need to

  20. Diffusion in silicon isotope heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Silvestri, Hughes Howland [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    The simultaneous diffusion of Si and the dopants B, P, and As has been studied by the use of a multilayer structure of isotopically enriched Si. This structure, consisting of 5 pairs of 120 nm thick natural Si and 28Si enriched layers, enables the observation of 30Si self-diffusion from the natural layers into the 28Si enriched layers, as well as dopant diffusion from an implanted source in an amorphous Si cap layer, via Secondary Ion Mass Spectrometry (SIMS). The dopant diffusion created regions of the multilayer structure that were extrinsic at the diffusion temperatures. In these regions, the Fermi level shift due to the extrinsic condition altered the concentration and charge state of the native defects involved in the diffusion process, which affected the dopant and self-diffusion. The simultaneously recorded diffusion profiles enabled the modeling of the coupled dopant and self-diffusion. From the modeling of the simultaneous diffusion, the dopant diffusion mechanisms, the native defect charge states, and the self- and dopant diffusion coefficients can be determined. This information is necessary to enhance the physical modeling of dopant diffusion in Si. It is of particular interest to the modeling of future electronic Si devices, where the nanometer-scale features have created the need for precise physical models of atomic diffusion in Si. The modeling of the experimental profiles of simultaneous diffusion of B and Si under p-type extrinsic conditions revealed that both species are mediated by neutral and singly, positively charged Si self-interstitials. The diffusion of As and Si under extrinsic n-type conditions yielded a model consisting of the interstitialcy and vacancy mechanisms of diffusion via singly negatively charged self-interstitials and neutral vacancies. The simultaneous diffusion of P and Si has been modeled on the basis of neutral and singly negatively charged self-interstitials and neutral and singly

  1. Modeling chlorine isotope trends during sequential transformation of chlorinated ethenes

    NARCIS (Netherlands)

    Hunkeler, D.; van Breukelen, B.M.; Elsner, M.

    2009-01-01

    There is increasing interest in combined carbon-chlorine compound-specific isotope analysis (CSIA) to differentiate between contaminant sources and to assess transformation processes. However, the significant abundance of polychlorinated molecules with several heavy chlorine isotopes complicates the

  2. The Mt Logan Holocene-late Wisconsinan isotope record

    DEFF Research Database (Denmark)

    Dahl-Jensen, Dorthe; Fisher, David; Osterberg, Erich

    2008-01-01

    Mt Logan • stable isotopes • Holocene • ENSO • peat • N Pacific • sudden change Udgivelsesdato: August......Mt Logan • stable isotopes • Holocene • ENSO • peat • N Pacific • sudden change Udgivelsesdato: August...

  3. Isotopic compositions of boron in sediments and their implications

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Yingkai, X.

    The abundance and isotopic compositions of boron in sediments from the salt lakes of Qaidam Basin, China have been determined by thermal ionization mass spectrometry of cesium borate. The results show large variations in the isotopic compositions...

  4. Production of medical 99 m Tc isotope via photonuclear reaction

    Science.gov (United States)

    Fujiwara, M.; Nakai, K.; Takahashi, N.; Hayakawa, T.; Shizuma, T.; Miyamoto, S.; Fan, G. T.; Takemoto, A.; Yamaguchi, M.; Nishimura, M.

    2017-01-01

    99 m Tc with a 6 hour half-life is one of the most important medical isotopes used for the Single-Photon Emission Computed Tomography (SPECT) inspection in hospitals of US, Canada, Europe and Japan. 99 m Tc isotopes are extracted by the milking method from parent 99Mo isotopes with a 66 hour half-life. The supply of 99Mo isotopes now encounters a serious crisis. Hospitals may not suitably receive 99Mo medical isotopes in near future, due to difficulties in production by research nuclear reactors. Many countries are now looking for alternative ways to generate 99Mo isotopes other than those with research reactors. We discuss a sustained availability of 99 m Tc isotopes via the nat Mo(γ, n) photonuclear reaction, and discuss to solve technical problems for extracting pure 99 m Tc isotopes from other output materials of photonuclear reactions.

  5. Biological signatures in clumped isotopes of O2

    Science.gov (United States)

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

    2015-04-01

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of “clumped” isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in 18O18O and 17O18O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling.

  6. Isotopic dependence of the caloric curve

    Science.gov (United States)

    Trautmann, W.; Adrich, P.; Aumann, T.; Bacri, C. O.; Barczyk, T.; Bassini, R.; Bianchin, S.; Boiano, C.; Botvina, A. S.; Boudard, A.; Brzychczyk, J.; Chbihi, A.; Cibor, J.; Czech, B.; De Napoli, M.; Ducret, J.-É.; Emling, H.; Frankland, J. D.; Hellström, M.; Henzlova, D.; Immè, G.; Iori, I.; Johansson, H.; Kezzar, K.; Lafriakh, A.; Le Fèvre, A.; Le Gentil, E.; Leifels, Y.; Lühning, J.; Łukasik, J.; Lynch, W. G.; Lynen, U.; Majka, Z.; Mocko, M.; Müller, W. F. J.; Mykulyak, A.; Orth, H.; Otte, A. N.; Palit, R.; Pawłowski, P.; Pullia, A.; Raciti, G.; Rapisarda, E.; Sann, H.; Schwarz, C.; Sfienti, C.; Simon, H.; Sümmerer, K.; Tsang, M. B.; Verde, G.; Volant, C.; Wallace, M.; Weick, H.; Wiechula, J.; Wieloch, A.; Zwiegliński, B.

    2009-04-01

    Isotopic effects in projectile fragmentation at relativistic energies have been studied with the ALADIN forward spectrometer at SIS. Stable and radioactive Sn and La beams with an incident energy of 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z ratio of the produced spectator sources, consistent with predictions for expanded systems. Consequences for the proposed interpretation of chemical breakup temperatures as representing the limiting temperatures predicted by microscopic models are discussed.

  7. Isotopic abundance in atom trap trace analysis

    Science.gov (United States)

    Lu, Zheng-Tian; Hu, Shiu-Ming; Jiang, Wei; Mueller, Peter

    2014-03-18

    A method and system for detecting ratios and amounts of isotopes of noble gases. The method and system is constructed to be able to measure noble gas isotopes in water and ice, which helps reveal the geological age of the samples and understand their movements. The method and system uses a combination of a cooled discharge source, a beam collimator, a beam slower and magneto-optic trap with a laser to apply resonance frequency energy to the noble gas to be quenched and detected.

  8. Precision Mass Measurement of Argon Isotopes

    CERN Multimedia

    Lunney, D

    2002-01-01

    % IS388\\\\ \\\\ A precision mass measurement of the neutron-deficient isotopes $^{32,33,34}$Ar is proposed. Mass values of these isotopes are of importance for: a) a stringent test of the Isobaric-Multiplet- Mass-Equation, b) a verification of the correctness of calculated charge-dependent corrections as used in super-allowed $\\beta$- decay studies aiming at a test of the CVC hypothesis, and c) the determination of the kinematics in electron-neutrino correlation experiments searching for scalar currents in weak interaction. The measurements will be carried out with the ISOLTRAP Penning trap mass spectrometer.

  9. Iron isotopes in an Archean ocean analogue

    Science.gov (United States)

    Busigny, Vincent; Planavsky, Noah J.; Jézéquel, Didier; Crowe, Sean; Louvat, Pascale; Moureau, Julien; Viollier, Eric; Lyons, Timothy W.

    2014-05-01

    Iron isotopes have been extensively used to trace the history of microbial metabolisms and the redox evolution of the oceans. Archean sedimentary rocks display greater variability in iron isotope ratios and more markedly negative values than those deposited in the Proterozoic and Phanerozoic. This increased variability has been linked to changes in either water column iron cycling or the extent of benthic microbial iron reduction through time. We tested these contrasting scenarios through a detailed study of anoxic and ferruginous Lac Pavin (France), which can serve as a modern analogue of the Archean ocean. A depth-profile in the water column of Lac Pavin shows a remarkable increase in dissolved Fe concentration (0.1-1200 μM) and δ56Fe values (-2.14‰ to +0.31‰) across the oxic-anoxic boundary to the lake bottom. The largest Fe isotope variability is found at the redox boundary and is related to partial oxidation of dissolved ferrous iron, leaving the residual Fe enriched in light isotopes. The analysis of four sediment cores collected along a lateral profile (one in the oxic layer, one at the redox boundary, one in the anoxic zone, and one at the bottom of the lake) indicates that bulk sediments, porewaters, and reactive Fe mostly have δ56Fe values near 0.0 ± 0.2‰, similar to detrital iron. In contrast, pyrite δ56Fe values in sub-chemocline cores (60, 65, and 92 m) are highly variable and show significant deviations from the detrital iron isotope composition (δ56Fepyrite between -1.51‰ and +0.09‰; average -0.93‰). Importantly, the pyrite δ56Fe values mirror the δ56Fe of dissolved iron at the redox boundary—where near quantitative sulfate and sulfide drawdown occurs—suggesting limited iron isotope fractionation during iron sulfide formation. This finding has important implications for the Archean environment. Specifically, this work suggests that in a ferruginous system, most of the Fe isotope variability observed in sedimentary pyrites can

  10. Iron isotope fractionation in planetary crusts

    OpenAIRE

    Wang, Kun; Moynier, Frédéric; Dauphas, Nicolas; Barrat, Jean-Alix,; Craddock, Paul; Sio, Corliss,

    2012-01-01

    International audience; We present new high precision iron isotope data (δ56Fe vs. IRMM-014 in per mil) for four groups of achondrites: one lunar meteorite, 11 martian meteorites, 32 howardite-eucrite-diogenite meteorites (HEDs), and eight angrites. Angrite meteorites are the only planetary materials, other than Earth/Moon system, significantly enriched in the heavy isotopes of Fe compared to chondrites (by an average of +0.12‰ in δ56Fe). While the reason for such fractionation is not complet...

  11. Isotope separation and advanced manufacturing technology

    Science.gov (United States)

    Carpenter, J.; Kan, T.

    This is the fourth issue of a semiannual report for the Isotope Separation and Advanced Materials Manufacturing (ISAM) Technology Program at Lawrence Livermore National Laboratory. Primary objectives include: (1) the Uranium Atomic Vapor Laser Isotope Separation (UAVLIS) process, which is being developed and prepared for deployment as an advanced uranium enrichment capability; (2) Advanced manufacturing technologies, which include industrial laser and E-beam material processing and new manufacturing technologies for uranium, plutonium, and other strategically important materials in support of DOE and other national applications. This report features progress in the ISAM Program from October 1993 through March 1994.

  12. Novel PEFC Application for Deuterium Isotope Separation

    Directory of Open Access Journals (Sweden)

    Hisayoshi Matsushima

    2017-03-01

    Full Text Available The use of a polymer electrolyte fuel cell (PEFC with a Nafion membrane for isotopic separation of deuterium (D was investigated. Mass analysis at the cathode side indicated that D diffused through the membrane and participated in an isotope exchange reaction. The exchange of D with protium (H in H2O was facilitated by a Pt catalyst. The anodic data showed that the separation efficiency was dependent on the D concentration in the source gas, whereby the water produced during the operation of the PEFC was more enriched in D as the D concentration of the source gas was increased.

  13. Isotopic effect on thermal physical properties of isotopically modified boron single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Quanli [Japan Science and Technology Corporation, Kawaguchi, Saitama (Japan); Noda, Tetsuji; Suzuki, Hiroshi; Araki, Hiroshi; Numazawa, Takenori; Hirano, Toshiyuki [National Institute for Materials Science, Tsukuba, Ibaraki (Japan); Nogi, Naoyuki; Tanaka, Satoru [University of Tokyo, Department of Quantum Engineering and Systems Science, Tokyo (Japan)

    2002-04-01

    The measurement of specific heat and thermal conductivity at low temperature for isotopically modified boron single crystals was performed between 0.5 and 100K using relaxation method and steady heat flow method, respectively. The results indicate that the specific heat has obvious divergences at T<5K. At 40K, the thermal conductivity of {sup 10}B-enriched crystal is about 570 W/m{center_dot}K, which is 40% larger than that of natural boron crystal. The influence of lattice vibration modes and the isotopic effect on specific heat and thermal conductivity for isotopically modified boron are discussed. (author)

  14. Determination of fission gas yields from isotope ratios

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg

    1983-01-01

    This paper describes a method of calculating the actual fission yield of Kr and Xe in nuclear fuel including the effect of neutron capture reactions and decay. The bases for this calculation are the cumulative yields (ref. 1) of Kr and Xe isotopes (or pairs of isotopes) which are unaffected...... by neutron capture reactions, and measured Kr and Xe isotope ratios. Also the burnup contribution from the different fissile heavy isotopes must be known in order to get accurate fission gas yields....

  15. Stable isotope deltas: Tiny, yet robust signatures in nature

    Science.gov (United States)

    Brand, Willi A.; Coplen, Tyler B.

    2012-01-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including 14C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. 13C, 2H, and 18O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as−25 per mil can be written as−25 mUr (or−2.5 cUr or−0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg ‘units’ are easily included (e.g. either+0.015 ‰ or+15 per meg

  16. Stable isotope deltas: tiny, yet robust signatures in nature.

    Science.gov (United States)

    Brand, Willi A; Coplen, Tyler B

    2012-09-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg

  17. Theoretical Evaluation of Intermolecular and Intramolecular Isotope Fractionations in Fragmentation

    OpenAIRE

    Tang, Caiming; Peng, Xianzhi

    2017-01-01

    Revelation of the effects of isotope fractionation during fragmentation in electron ionization mass spectrometry (EI-MS) on compound-specific isotope analysis of chlorine and bromine (CSIA-Cl/Br) may be of crucial significance, yet a theoretical basis for elucidating the effects is absent. This study provides a solid theoretical deduction regarding the isotope fractionation taking place during fragmentation in EI-MS. Both intermolecular and intramolecular isotope fractionations present in deh...

  18. Systematic text condensation

    DEFF Research Database (Denmark)

    Malterud, Kirsti

    2012-01-01

    To present background, principles, and procedures for a strategy for qualitative analysis called systematic text condensation and discuss this approach compared with related strategies.......To present background, principles, and procedures for a strategy for qualitative analysis called systematic text condensation and discuss this approach compared with related strategies....

  19. The Importance of Systematics

    Indian Academy of Sciences (India)

    1999-02-18

    Feb 18, 1999 ... T C Narendran has specialised in Systematic. Entomology with particu- lar reference to parasitic. Hymenoptera. He is at the Department of. Zoology, University of. Calicut. He has done research at the Systematic. Entomology Laboratory of the US National Musuem of Natural History,. Washington D.C. and at.

  20. Lead Isotopes in Olivine-Phyric Shergottite Tissint: Implications for the Geochemical Evolution of the Shergottite Source Mantle

    Science.gov (United States)

    Moriwaki, R.; Usui, T.; Simon, J. I.; Jones, J. H.; Yokoyama, T.

    2015-01-01

    Geochemically-depleted shergottites are basaltic rocks derived from a martian mantle source reservoir. Geochemical evolution of the martian mantle has been investigated mainly based on the Rb-Sr, Sm-Nd, and Lu-Hf isotope systematics of the shergottites [1]. Although potentially informative, U-Th- Pb isotope systematics have been limited because of difficulties in interpreting the analyses of depleted meteorite samples that are more susceptible to the effects of near-surface processes and terrestrial contamination. This study conducts a 5-step sequential acid leaching experiment of the first witnessed fall of the geochemically-depleted olivinephyric shergottite Tissint to minimize the effect of low temperature distrubence. Trace element analyses of the Tissint acid residue (mostly pyroxene) indicate that Pb isotope compositions of the residue do not contain either a martian surface or terrestrial component, but represent the Tissint magma source [2]. The residue has relatively unradiogenic initial Pb isotopic compositions (e.g., 206Pb/204Pb = 10.8136) that fall within the Pb isotope space of other geochemically-depleted shergottites. An initial µ-value (238U/204Pb = 1.5) of Tissint at the time of crystallization (472 Ma [3]) is similar to a time-integrated mu- value (1.72 at 472 Ma) of the Tissint source mantle calculated based on the two-stage mantle evolution model [1]. On the other hand, the other geochemically-depleted shergottites (e.g., QUE 94201 [4]) have initial µ-values of their parental magmas distinctly lower than those of their modeled source mantle. These results suggest that only Tissint potentially reflects the geochemical signature of the shergottite mantle source that originated from cumulates of the martian magma ocean

  1. Use of dual isotope tracers in biomedical research

    NARCIS (Netherlands)

    Stellaard, F

    Biomedical stable isotope studies involve administration of tracer and measurement of isotope enrichment in blood, urine, feces or breath. The aim of the studies is to gather quantitative information about a specific metabolic function. However, the measured isotope enrichment may be affected by

  2. Discovery of palladium, antimony, tellurium, iodine, and xenon isotopes

    CERN Document Server

    Kathawa, J; Thoennessen, M

    2012-01-01

    Currently, thirty-eight palladium, thirty-eight antimony, thirty-nine tellurium, thirty-eight iodine, and forty xenon isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  3. Discovery of the astatine, radon, francium, and radium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Fry, C.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

    2013-09-15

    Thirty-nine astatine, thirty-nine radon, thirty-five francium, and thirty-four radium isotopes have so far been observed; the discovery of these isotopes is described. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  4. Discovery of the astatine, radon, francium, and radium isotopes

    CERN Document Server

    Fry, C

    2012-01-01

    Currently, thirty-nine astatine, thirty-nine radon, thirty-five francium, and thirty-four radium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  5. Discovery of the astatine, radon, francium, and radium isotopes

    Science.gov (United States)

    Fry, C.; Thoennessen, M.

    2013-09-01

    Thirty-nine astatine, thirty-nine radon, thirty-five francium, and thirty-four radium isotopes have so far been observed; the discovery of these isotopes is described. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  6. Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes

    CERN Document Server

    Gross, J L

    2011-01-01

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  7. Towards a "perfect" Penning trap mass spectrometer for unstable isotopes

    Science.gov (United States)

    Bollen, G.; Hartmann, H.; Kluge, H.-J.; König, M.; Otto, T.; Savard, G.; Stolzenberg, H.; ISOLDE Collaboration

    1992-12-01

    A Penning trap mass spectrometer has been set up at the on-line isotope separator ISOLDE/CERN for the mass determination of unstable heavy isotopes. The spectrometer should fulfil the following requirements: capture of external ions in high efficiency, high resolving power and accuracy, general applicability to all elements and isotopes available at the on-line facility.

  8. 21 CFR 886.1670 - Ophthalmic isotope uptake probe.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic isotope uptake probe. 886.1670 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1670 Ophthalmic isotope uptake probe. (a) Identification. An ophthalmic isotope uptake probe is an AC-powered device intended to measure...

  9. Production and application of stable enriched isotopes in the USSR

    Energy Technology Data Exchange (ETDEWEB)

    Kudziev, A.G. (Institute of Stable Isotopes, Tbilisi (USSR))

    1989-10-01

    At present stable enriched isotopes are contributing essentially to the progress in many fields of sciences and national economy. The application of isotopically modified compounds and materials allowed to obtain a number of remarkable scientific results and initiated developments of great applied significance. This presentation will survey status and development activities involving enriched stable isotopes in the USSR. (orig.).

  10. Recent results on neutron rich tin isotopes by laser spectroscopy

    CERN Document Server

    Roussière, B; Crawford, J E; Essabaa, S; Fedosseev, V; Geithner, W; Genevey, J; Girod, M; Huber, G; Horn, R; Kappertz, S; Lassen, J; Le Blanc, F; Lee, J K P; Le Scornet, G; Lettry, Jacques; Mishin, V I; Neugart, R; Obert, J; Oms, J; Ouchrif, A; Peru, S; Pinard, J; Ravn, H L; Sauvage, J; Verney, D

    2001-01-01

    Laser spectroscopy measurements have been performed on neutron rich tin isotopes using the COMPLIS experimental setup. The nuclear charge radii of the even-even isotopes from A=108 to 132 are compared to the results of macroscopic and microscopic calculations. The improvements and optimizations needed to perform the isotope shift measurement on $^{134}$Sn are presented.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  12. Stable Isotope Characteristics of Akiri Vein Copper Mineralization ...

    African Journals Online (AJOL)

    The Akiri vein copper mineralization was investigated for its carbon and oxygen isotopic composition to determine the characteristics of the mineralizing fluid. Carbon and oxygen isotope analyses of Akiri siderite range between δ13C values (-1.05 to -1.71‰) and δ13O values (-14.94 to -15.18) respectively. δ 13C isotopic ...

  13. Atmospheric Argon Isotope Evolution Informed by MAVEN Results

    Science.gov (United States)

    Slipski, M.; Jakosky, B. M.; Benna, M.; Mahaffy, P.; Elrod, M. K.

    2017-10-01

    Mars' atmosphere is enriched in heavy isotopes of its major species. We have modeled the evolution of Ar isotopes of 4 Gyr due to volcanic outgassing and loss to space, using MAVEN results to constrain how sputtering loss fractionates Ar isotopes.

  14. The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile - Marine sources and diagenetic effects.

    Science.gov (United States)

    Lucassen, Friedrich; Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A

    2017-01-01

    Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very

  15. The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile - Marine sources and diagenetic effects.

    Directory of Open Access Journals (Sweden)

    Friedrich Lucassen

    Full Text Available Seabird excrements (guano have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic

  16. The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile – Marine sources and diagenetic effects

    Science.gov (United States)

    Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A.

    2017-01-01

    Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very

  17. Platinum isotopes in iron meteorites: Galactic cosmic ray effects and nucleosynthetic homogeneity in the p-process isotope 190Pt and the other platinum isotopes

    Science.gov (United States)

    Hunt, Alison C.; Ek, Mattias; Schönbächler, Maria

    2017-11-01

    Platinum isotopes are sensitive to the effects of galactic cosmic rays (GCR), which can alter isotope ratios and mask nucleosynthetic isotope variations. Platinum also features one p-process isotope, 190Pt, which is very low abundance and therefore challenging to analyse. Platinum-190 is relevant for early solar-system chronology because of its decay to 186Os. Here, we present new Pt isotope data for five iron meteorite groups (IAB, IIAB, IID, IIIAB and IVA), including high-precision measurements of 190Pt for the IAB, IIAB and IIIAB irons, determined by multi-collector ICPMS. New data are in good agreement with previous studies and display correlations between different Pt isotopes. The slopes of these correlations are well-reproduced by the available GCR models. We report Pt isotope ratios for the IID meteorite Carbo that are consistently higher than the predicted effects from the GCR model. This suggests that the model predictions do not fully account for all the GCR effects on Pt isotopes, but also that the pre-atmospheric radii and exposure times calculated for Carbo may be incorrect. Despite this, the good agreement of relative effects in Pt isotopes with the predicted GCR trends confirms that Pt isotopes are a useful in-situ neutron dosimeter. Once GCR effects are accounted for, our new dataset reveals s- and r-process homogeneity between the iron meteorite groups studied here and the Earth. New 190Pt data for the IAB, IIAB and IIIAB iron meteorites indicate the absence of GCR effects and homogeneity in the p-process isotope between these groups and the Earth. This corresponds well with results from other heavy p-process isotopes and suggests their homogenous distribution in the inner solar system, although it does not exclude that potential p-process isotope variations are too diluted to be currently detectable.

  18. Isotope fingerprinting of precipitation associated with western ...

    Indian Academy of Sciences (India)

    Ghulam Jeelani

    2017-11-22

    Nov 22, 2017 ... by geographic factors such as altitude, latitude, moisture source, and transport process (e.g., Craig. 1961; Siegenthaler and Oeschger 1980; Gat 1996; ..... cel over the continent, its isotopic composition is expected to change from its initial value due to various processes like picking up of locally recycled.

  19. Isotope specific arbitrary material flow meter

    Science.gov (United States)

    Barty, Christopher P. J.; Post, John C.; Jones, Edwin

    2016-10-25

    A laser-based mono-energetic gamma-ray source is used to provide non-destructive and non-intrusive, quantitative determination of the absolute amount of a specific isotope contained within pipe as part of a moving fluid or quasi-fluid material stream.

  20. Isotope effects on the crotonase reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bahnson, B.J.; Anderson, V.E. (Brown Univ., Providence, RI (USA))

    1989-05-16

    The primary, alpha-secondary, beta-secondary, and beta'-secondary deuterium and primary 18O kinetic isotope effects on V/K for the dehydration of ((3S)-3-hydroxybutyryl)pantetheine by bovine liver crotonase (enoyl-CoA hydratase, EC 4.2.1.17) have been determined by the equilibrium perturbation method. The primary deuterium and 18O kinetic isotope effects are 1.61 and 1.051, respectively. The secondary deuterium effects at C-2, C-3, and C-4 are 1.12, 1.13, and 1.00 per H, respectively. The large 18O isotope effect suggests C-O bond cleavage is largely rate determining but is consistent with either an E1cb or E2 mechanism with a large amount of carbanion character. The beta-secondary effect is a factor of 1.05 greater than the equilibrium isotope effect, indicating that this C-H bond is less stiff in the affected transition state or that its motion is coupled to the reaction coordinate motion. Analytical solutions to the differential equations describing uni-uni equilibrium perturbations are presented.

  1. Seabird modulations of isotopic nitrogen on islands.

    Directory of Open Access Journals (Sweden)

    Stéphane Caut

    Full Text Available The transport of nutrients by migratory animals across ecosystem boundaries can significantly enrich recipient food webs, thereby shaping the ecosystems' structure and function. To illustrate the potential role of islands in enabling the transfer of matter across ecosystem boundaries to be gauged, we investigated the influence of seabirds on nitrogen input on islands. Basing our study on four widely differing islands in terms of their biogeography and ecological characteristics, sampled at different spatial and temporal intervals, we analyzed the nitrogen isotopic values of the main terrestrial ecosystem compartments (vascular plants, arthropods, lizards and rodents and their relationship to seabird values. For each island, the isotopic values of the ecosystem were driven by those of seabirds, which ultimately corresponded to changes in their marine prey. First, terrestrial compartments sampled within seabird colonies were the most enriched in δ(15N compared with those collected at various distances outside colonies. Second, isotopic values of the whole terrestrial ecosystems changed over time, reflecting the values of seabirds and their prey, showing a fast turnover throughout the ecosystems. Our results demonstrate that seabird-derived nutrients not only spread across the terrestrial ecosystems and trophic webs, but also modulate their isotopic values locally and temporally on these islands. The wealth of experimental possibilities in insular ecosystems justifies greater use of these model systems to further our understanding of the modalities of trans-boundary nutrient transfers.

  2. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    titative measurements of equilibrium and kinetic isotope effects. In this part, we describe an ingenious way of studying ... is whether the structure obtained is the preferred one or just the superposition of some other equilibrating structures. ... Ammonia is a pyramidal molecule, but it undergoes rapid umbrella inversion. On the ...

  3. Function and application of isotope controlled materials

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, Koichi; Suzuki, Hiroshi; Araki, Hiroshi; Fujita, Mitsutane; Hirano, Toshiyuki; Numazawa, Takenori; Noda, Tetsuji [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)

    2000-02-01

    As large amounts of silicone isotopes were separated in previous research, we tried to develop function of isotope controlled materials. Molecular vibration excitation control to control laser wavelength, physical properties of isotope control materials and nuclear transformation function were studied. A gas circulation system for isotope laser development was manufactured. When a part of {sup 16}O in CO{sub 2} were changed by {sup 18}O, the stretching mode of CO{sub 2} became unsymmetrical mode. P17 and P19 of laser oscillation were observed. They are odd lines that have never been observed. SiF{sub 4} and Si{sub 2}F{sub 6} were decomposed by plasma CVD method. About 28% Si crystal was obtained by controlling the reaction temperature at about 350 to 450degC. Homogeneous P single crystal(100) with 10 mm diameter was obtained. Thermal conductivity of B single crystal with {sup 10}B showed 1.5 times as much as that of natural components. Calculation of displacement damages, change of components, induced radioactivity and decay heat were improved by arrangement of simulation code. (S.Y.)

  4. Tomographic, hydrochemical and isotopic investigations of the ...

    Indian Academy of Sciences (India)

    An electrical imaging tomography survey was carried out to identify the lateral and vertical salinity distribution in the oasis shallow aquifers of the Nefzaoua region located in southwestern Tunisia. In addition, hydrochemical and isotopic data were examined to determine the main factors and mechanisms controlling the ...

  5. Stable carbon isotope analysis of coprocessing materials

    Energy Technology Data Exchange (ETDEWEB)

    Burke, F. P.; Winschel, R. A.; Lancet, M. S.

    1989-06-01

    The program is designed to address a substantial, demonstrated need of the coprocessing community (both exploratory and development) for a technique to quantitatively distinguish the contributions of the individual coprocessing feedstocks to the various products. The carbon isotope technique is currently in routine use for other applications. Results achieved this quarter include: Feed and product fractions from a Kentucky 9 coal/Kentucky tar sand bitumen coprocessing bench unit run at the Kentucky Center for Applied Energy Research (CAER) were analyzed for carbon isotope ratios. Corrections were made to the coal carbon recoveries and selectivities from the products of HRI Run 227-53. Feeds (Westerholt coal/Cold Lake VSB) and products from two periods of HRI coprocessing Run 238-1 were analyzed. Three petroleum samples and three coal samples were pyro