WorldWideScience

Sample records for isotopic record contributions

  1. Paleogene Seawater Osmium Isotope Records

    Science.gov (United States)

    Rolewicz, Z.; Thomas, D. J.; Marcantonio, F.

    2012-12-01

    Paleoceanographic reconstructions of the Late Cretaceous and early Cenozoic require enhanced geographic coverage, particularly in the Pacific, in order to better constrain meridional variations in environmental conditions. The challenge with the existing inventory of Pacific deep-sea cores is that they consist almost exclusively of pelagic clay with little existing age control. Pelagic clay sequences are useful for reconstructions of dust accumulation and water mass composition, but accurate correlation of these records to other sites requires improved age control. Recent work indicates that seawater Os isotope analyses provide useful age control for red clay sequences. The residence time of Os in seawater is relatively long compared to oceanic mixing, therefore the global seawater 187Os/188Os composition is practically homogeneous. A growing body of Late Cretaceous and Cenozoic data has constrained the evolution of the seawater Os isotopic composition and this curve is now a viable stratigraphic tool, employed in dating layers of Fe-Mn crusts (e.g., Klemm et al., 2005). Ravizza (2007) also demonstrated that the seawater Os isotopic composition can be extracted reliably from pelagic red clay sediments by analyzing the leached oxide minerals. The drawback to using seawater Os isotope stratigraphy to date Paleogene age sediments is that the compilation of existing data has some significant temporal gaps, notably between ~38 and 55 Ma. To improve the temporal resolution of the seawater Os isotope curve, we present new data from Ocean Drilling Program (ODP) Site 865 in the equatorial Pacific. Site 865 has excellent biostratigraphic age control over the interval ~38-55Ma. Preliminary data indicate an increase in the seawater composition from 0.427 at 53.4 Ma to 0.499 by 43 Ma, consistent with the apparent trend in the few existing data points. We also analyzed the Os isotopic composition recorded by oxide minerals at Integrated Ocean Drilling Program (IODP) Site U1370

  2. Major events in Neogene oxygen isotopic records

    International Nuclear Information System (INIS)

    Kennett, J.P.; Hodell, D.A.

    1986-01-01

    Changes in oxygen isotopic ratios of foraminiferal calcite during the cainozoic have been one of the primary tools for investigating the history of Arctic and Antarctic glaciation, although interpretations of the oxygen isotopic record differ markedly. The ambiguity in interpretation results mainly from the partitioning of temperature from ice volume effects in delta 18 O changes. Oxygen isotopic records for the Cainozoic show an increase in delta 18 O values towards the present, reflecting gradual cooling and increased glaciation of the Earth's climate since the late Cretaceous. A variety of core material from the South Atlantic and South-west Pacific oceans are investigated. This composite data represents one of the most complete available with which to evaluate the evolution of glaciation during the Neogene. Expansion of ice shelves in Antarctica undoubtedly accompanied the increased glaciation of the northern hemisphere, since eustatic sea-level lowering would positively reinforce ice growth on Antarctica

  3. Biomineralization and the carbon isotope record

    International Nuclear Information System (INIS)

    Degens, E.T.; Ittekkot, V.; Kazmierczak, J.

    1986-01-01

    The advent of biomineralization at the turn of the Precambrian/Cambrian boundary has been a major event in the Earth's evolutionary history. With this there has been a major shift from abiotic to biotic formation of minerals such as phosphates and carbonates and, subsequently, silica. The dominant factor which effected this shift is a change in ocean's chemistry with respect to its Ca 2+ and mineral nutrient contents. Mechanism controlling the biotic mineral formation is different from that controlling the abiotic one in that the former is enzymically controlled. It is suggested that this difference is also manifested in the stable carbon isotope fractionation between the two processes and has implication for the interpretation of stable carbon isotope record. (Author)

  4. Argon isotopes as recorders of magmatic processes

    Science.gov (United States)

    Layer, P. W.; Gardner, J. E.; Mora Chaparro, J. C.; Arce, J. L.

    2003-12-01

    Argon isotopic ratios vary enough between different reservoirs (atmosphere, crust, mantle) and diffuse fast enough through most minerals at magmatic temperatures (700-1200 C) to make them ideal for looking at magma chamber dynamics. Indeed, diffusion is sufficiently fast to allow short time scales to be deciphered, setting argon apart from many other isotopic methods. A mineral's ability to retain "excess" argon (40Ar/36Ar ratios greater than the atmospheric value and apparent ages older than the known eruption age) during post-eruption cooling is key to Ar studies. Previous work shows that both phenocrysts (crystallizing in the magma chamber; e.g. Mt St. Helens; Layer and Gardner, 2001) and xenocrysts (introduced into the magma chamber; e.g Toba; Gardner et al., 2002) preserve excess argon, which enables magma chamber processes to be deciphered through the variable diffusion rates between crystal phases. Single crystal 40Ar/39Ar step-heating of biotite from the 10.5 ka eruption of Nevado de Toluca volcano, Mexico indicates that they are xenocrystic and resided for only a short (< 1 year) time in the magma before it erupted. The biotite has reaction rims of hornblende, orthopyroxene and plagioclase, and failed to grow experimentally at pressure-temperature conditions of the magma, confirming the xenocrystic nature of this phase. Single-step fusion of plagioclase phenocrysts from eruptions of El Chichon volcano, Mexico, shows evidence of excess (mantle) argon, whereas hornblende from the same eruptions contains little or none. In this case, faster diffusion of Ar in plagioclase than in hornblende allow plagioclase to incorporate excess argon during magma recharge; hornblende does not. Combining such results with other isotopic systems may in fact better determine magma chamber processes. At El Chichon, Sr isotopes suggest magma recharges ocurred (Tepley et al., 2000), whereas the argon isotopes suggest such pulses occurred just before each eruption. The fast and

  5. Age of underground waters: isotopes contribution

    International Nuclear Information System (INIS)

    Chery, L.; Olive, Ph.

    2006-01-01

    Does water has an age? The age of underground waters can be the duration of their underground travel between their infiltration inside the ground and their captation at a spring or a drilled well. The isotopic geochemistry comes to the support of classical geochemistry to estimate these residence times. Radio-isotopes, like tritium for young waters or carbon 14 for old waters, are used as chronometers to interpret the recharge ways, the flow mechanisms and the residence times of underground waters. Their use is presented in this article with some theoretical recalls and some examples of application. (J.S.)

  6. Climate variability from isotope records in precipitation

    International Nuclear Information System (INIS)

    Grassl, H.; Latif, M.; Schotterer, U.; Gourcy, L.

    2002-01-01

    Selected time series from the Global Network for Isotopes in Precipitation (GNIP) revealed a close relationship to climate variability phenomena like El Nino - Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO) although the precipitation anomaly in the case studies of Manaus (Brazil) and Groningen (The Netherlands) is rather weak. For a sound understanding of this relationship especially in the case of Manaus, the data should include major events like the 1997/98 El Nino, however, the time series are interrupted frequently or important stations are even closed. Improvements are only possible if existing key stations and new ones (placed at 'hot spots' derived from model experiments) are supported continuously. A close link of GNIP to important scientific programmes like CLIVAR, the Climate Variability and Predictability Programme seems to be indispensable for a successful continuation. (author)

  7. Kinetic control on Zn isotope signatures recorded in marine diatoms

    Science.gov (United States)

    Köbberich, Michael; Vance, Derek

    2017-08-01

    Marine diatoms dominate the oceanic cycle of the essential micronutrient zinc (Zn). The stable isotopes of zinc and other metals are increasingly used to understand trace metal micronutrient cycling in the oceans. One clear feature of the early isotope data is the heavy Zn isotope signature of the average oceanic dissolved pool relative to the inputs, potentially driven by uptake of light isotopes into phytoplankton cells and export to sediments. However, despite the fact that diatoms strip Zn from surface waters across the Antarctic polar front in the Southern Ocean, the local upper ocean is not isotopically heavy. Here we use culturing experiments to quantify the extent of Zn isotope fractionation by diatoms and to elucidate the mechanisms driving it. We have cultured two different open-ocean diatom species (T. oceanica and Chaetoceros sp.) in a series of experiments at constant medium Zn concentration but at bioavailable medium Fe ranging from limiting to replete. We find that T. oceanica can maintain high growth rates and Zn uptake rates over the full range of bioavailable iron (Fe) investigated, and that the Zn taken up has a δ66Zn that is unfractionated relative to that of the bioavailable free Zn in the medium. The studied representative of the genus Chaetoceros, on the other hand, shows more significantly reduced Zn uptake rates at low Fe and records more variable biomass δ66Zn signatures, of up to 0.85‰ heavier than the medium. We interpret the preferential uptake of heavy isotopes at extremely low Zn uptake rates as potentially due to either of the following two mechanisms. First, the release of extracellular polymeric substances (EPS), at low Fe levels, may preferentially scavenge heavy Zn isotopes. Second, the Zn uptake rate may be slow enough to establish pseudo-equilibrium conditions at the transporter site, with heavy Zn isotopes forming more stable surface complexes. Thus we find that, in our experiments, Fe-limitation exerts a key control that

  8. Preservation of Fe Isotope Proxies in the Rock Record

    Science.gov (United States)

    Johnson, C.; Beard, B.; Valley, J.; Valaas, E.

    2005-12-01

    Iron isotope variations provide powerful constraints on redox conditions and pathways involved during biogeochemical cycling of Fe in surface and near-surface environments. The relative isotopic homogeneity of igneous rocks and most bulk weathering products contrasts with the significant isotopic variations (4 per mil in 56Fe/54Fe) that accompany oxidation of Fe(II)aq, precipitation of sulfides, and reduction by bacteria. These isotopic variations often reflect intrinsic (equilibrium) Fe isotope fractionations between minerals and aqueous species whose interactions may be directly or indirectly catalyzed by bacteria. In addition, Fe isotope exchange may be limited between reactive Fe pools in low-temperature aqueous-sediment environments, fundamentally reflecting disequilibrium effects. In the absence of significant sulfide, dissimilatory Fe(III) reduction by bacteria produces relatively low 56Fe/54Fe ratios for Fe(II)aq and associated biogenic minerals such as magnetite and siderite. In contrast, Fe(II)aq that exchanges with Fe sulfides (FeS and pyrite) is relatively enriched in 56Fe/54Fe ratios. In modern and ancient environments, anoxic diagenesis tends to produce products that have low 56Fe/54Fe ratios, whereas oxidation of Fe(II)aq from hydrothermal sources tends to produce ferric Fe products that have high 56Fe/54Fe ratios. Redox cycling by bacteria tends to produce reactive ferric Fe reservoirs that have low 56Fe/54Fe ratios. Application of Fe isotopes as a proxy for redox conditions in the ancient rock record depends upon the preservation potential during metamorphism, given the fact that most Archean sedimentary sequences have been subjected to regional greenschist- to granulite-facies metamorphism. The 1.9 Ga banded iron formations (BIFs) of the Lake Superior region that are intruded by large ~1 Ga intrusions (e.g., Duluth gabbro) provide a test of the preservation potential for primary, low-temperature Fe isotope variations in sedimentary rocks. 56Fe/54

  9. Isotopic Recorders of Pollution in Heterogeneous Urban Areas

    Science.gov (United States)

    Pataki, D. E.; Cobley, L.; Smith, R. M.; Ehleringer, J. R.; Chritz, K.

    2017-12-01

    A significant difficulty in quantifying urban pollution lies in the extreme spatial and temporal heterogeneity of cities. Dense sources of both point and non-point source pollution as well as the dynamic role of human activities, which vary over very short time scales and small spatial scales, complicate efforts to establish long-term urban monitoring networks that are relevant at neighborhood, municipal, and regional scales. Fortunately, the natural abundance of isotopes of carbon, nitrogen, and other elements provides a wealth of information about the sources and fate of urban atmospheric pollution. In particular, soils and plant material integrate pollution sources and cycling over space and time, and have the potential to provide long-term records of pollution dynamics that extend back before atmospheric monitoring data are available. Similarly, sampling organic material at high spatial resolution can provide "isoscapes" that shed light on the spatial heterogeneity of pollutants in different urban parcels and neighborhoods, along roads of varying traffic density, and across neighborhoods of varying affluence and sociodemographic composition. We have compiled numerous datasets of the isotopic composition of urban organic matter that illustrate the potential for isotopic monitoring of urban areas as a means of understanding hot spots and hot moments in urban atmospheric biogeochemistry. Findings to date already reveal the critical role of affluence, economic activity, demographic change, and land management practices in influencing urban pollution sources and sinks, and suggest an important role of stable isotope and radioisotope measurements in urban atmospheric and biogeochemical monitoring.

  10. Reassessing the stable water isotope record in understanding past climate

    International Nuclear Information System (INIS)

    Noone, D.; Simmonds, I.

    1999-01-01

    Full text: The impact of atmospheric circulation on the stable water isotope record has been examined using an atmospheric general circulation model to reassess the validity of using isotopes to reconstruct Earth's climate history. Global temperature changes are classically estimated from the variations in (polar) isotopic values assuming a simple linear relationship. Such a relationship can be justified from first order theoretical considerations given that the isotopic fractionation at the deposition (ice core) site is temperature dependent. However, it is found that the history of a given air mass is more important that local processes because of the net effect of condensation events active along the transport pathway from the source region. Modulations in the hemispheric flow are seen to be crucial to Antarctic precipitation and the isotopic signal. Similarly, both transient and stationary disturbances influence the pathways of the air masses associated with Antarctic precipitation. During different climate regimes, such as that of the Last Glacial Maximum, the properties of these types of disturbances may not be assumed to be the same. As such, we may not assume that the condensation histories are the same as under different climate conditions. Therefore, the veracity of the linear climate reconstructions becomes questionable. Notwithstanding this result, the types of changes to the circulation regime that are expected generally correspond to changes in the global temperature. This fortunate result does not disallow the use of regressional reconstruction, however, the uncertainties associated with these circulation changes are of the same magnitude as the differences suggested by conventional linear regression in climate reconstruction. This indicates that interpretation of ice core data must be accompanied by detailed examination of the atmospheric processes and quantification of the impacts of their changes. Copyright (1999) Geological Society of Australia

  11. A small-scale computerized isotope record monitoring system

    International Nuclear Information System (INIS)

    Richards, L.

    1979-01-01

    A system in use at Queen Elizabeth College for monitoring the isotopes used by radiation workers and the precautionary medical screening of the workers is described. It consists of a PDP-11 minicomputer and flexible disk storage system. The machine is run under a single-user, real-time operating system and is linked on-line to a teleprinter and a VDU. Data is stored as a series of files, each relating to an individual worker, which can be updated individually from the VDU. The files contain information on the worker's project and medical screening records, and his holdings of isotopes and their use and disposal. A warning is printed automatically if a worker's holding exceeds the allowed maximum. The total quantity of isotopes held and their distribution in an institution such as a university can easily be monitored so that legal limits can be adhered to. The system is inexpensive and can be used by personnel not familiar with computer systems. (author)

  12. Small-scale computerized isotope record monitoring system

    Energy Technology Data Exchange (ETDEWEB)

    Richards, L [Queen Elizabeth Coll., London (UK)

    1979-05-01

    A system in use at Queen Elizabeth College for monitoring the isotopes used by radiation workers and the precautionary medical screening of the workers is described. It consists of a PDP-11 minicomputer and flexible disk storage system. The machine is run under a single-user, real-time operating system and is linked on-line to a teleprinter and a VDU. Data is stored as a series of files, each relating to an individual worker, which can be updated individually from the VDU. The files contain information on the worker's project and medical screening records, and his holdings of isotopes and their use and disposal. A warning is printed automatically if a worker's holding exceeds the allowed maximum. The total quantity of isotopes held and their distribution in an institution such as a university can easily be monitored so that legal limits can be adhered to. The system is inexpensive and can be used by personnel not familiar with computer systems.

  13. Modeling the isotopic composition of Antarctic snow using backward trajectories: simulation of snow pit records

    NARCIS (Netherlands)

    Helsen, M.M.; van de Wal, R.S.W.; van den Broeke, M.R.; Masson-Delmotte, V.; Meijer, H.A.J.; Scheele, M.P.; Werner, M.

    2006-01-01

    The quantitative interpretation of isotope records (d18O, dD, and d excess) in ice cores can benefit from a comparison of observed meteorology with associated isotope variability. For this reason we studied four isotope records from snow pits in western Dronning Maud Land (DML), Antarctica, covering

  14. The magnesium isotope record of cave carbonate archives

    Science.gov (United States)

    Riechelmann, S.; Buhl, D.; Schröder-Ritzrau, A.; Riechelmann, D. F. C.; Richter, D. K.; Vonhof, H. B.; Wassenburg, J. A.; Geske, A.; Spötl, C.; Immenhauser, A.

    2012-11-01

    Here we explore the potential of magnesium (δ26Mg) isotope time-series data as continental climate proxies in speleothem calcite archives. For this purpose, a total of six Pleistocene and Holocene stalagmites from caves in Germany, Morocco and Peru and two flowstones from a cave in Austria were investigated. These caves represent the semi-arid to arid (Morocco), the warm-temperate (Germany), the equatorial-humid (Peru) and the cold-humid (Austria) climate zones. Changes in the calcite magnesium isotope signature with time are compared against carbon and oxygen isotope records from these speleothems. Similar to other proxies, the non-trivial interaction of a number of environmental, equilibrium and disequilibrium processes governs the δ26Mg fractionation in continental settings. These include the different sources of magnesium isotopes such as rainwater or snow as well as soil and host rock, soil zone biogenic activity, shifts in silicate versus carbonate weathering ratios and residence time of water in the soil and karst zone. Pleistocene stalagmites from Morocco show the lowest mean δ26Mg values (GDA: -4.26 ± 0.07‰ and HK3: -4.17 ± 0.15‰), and the data are well explained in terms of changes in aridity over time. The Pleistocene to Holocene stalagmites from Peru show the highest mean value of all stalagmites (NC-A and NC-B δ26Mg: -3.96 ± 0.04‰) but only minor variations in Mg-isotope composition, which is consistent with the rather stable equatorial climate at this site. Holocene stalagmites from Germany (AH-1 mean δ26Mg: -4.01 ± 0.07‰; BU 4 mean δ26Mg: -4.20 ± 0.10‰) suggest changes in outside air temperature was the principal driver rather than rainfall amount. The alpine Pleistocene flowstones from Austria (SPA 52: -3.00 ± 0.73‰; SPA 59: -3.70 ± 0.43‰) are affected by glacial versus interglacial climate change with outside air temperature affecting soil zone activity and weathering balance. Several δ26Mg values of the Austrian and two

  15. The magnesium isotope record of cave carbonate archives

    Directory of Open Access Journals (Sweden)

    S. Riechelmann

    2012-11-01

    Full Text Available Here we explore the potential of magnesium (δ26Mg isotope time-series data as continental climate proxies in speleothem calcite archives. For this purpose, a total of six Pleistocene and Holocene stalagmites from caves in Germany, Morocco and Peru and two flowstones from a cave in Austria were investigated. These caves represent the semi-arid to arid (Morocco, the warm-temperate (Germany, the equatorial-humid (Peru and the cold-humid (Austria climate zones. Changes in the calcite magnesium isotope signature with time are compared against carbon and oxygen isotope records from these speleothems. Similar to other proxies, the non-trivial interaction of a number of environmental, equilibrium and disequilibrium processes governs the δ26Mg fractionation in continental settings. These include the different sources of magnesium isotopes such as rainwater or snow as well as soil and host rock, soil zone biogenic activity, shifts in silicate versus carbonate weathering ratios and residence time of water in the soil and karst zone. Pleistocene stalagmites from Morocco show the lowest mean δ26Mg values (GDA: −4.26 ± 0.07‰ and HK3: −4.17 ± 0.15‰, and the data are well explained in terms of changes in aridity over time. The Pleistocene to Holocene stalagmites from Peru show the highest mean value of all stalagmites (NC-A and NC-B δ26Mg: −3.96 ± 0.04‰ but only minor variations in Mg-isotope composition, which is consistent with the rather stable equatorial climate at this site. Holocene stalagmites from Germany (AH-1 mean δ26Mg: −4.01 ± 0.07‰; BU 4 mean δ26Mg: −4.20 ± 0.10‰ suggest changes in outside air temperature was the principal driver rather than rainfall amount. The alpine Pleistocene flowstones from Austria (SPA 52: −3.00 ± 0.73‰; SPA 59: −3.70 ± 0.43‰ are affected by glacial versus interglacial climate change with outside air temperature

  16. Decoding mass-independent fractionation of sulfur isotopes in modern atmosphere using cosmogenic 35S: A five-isotope approach and possible implications for Archean sulfur isotope records

    Science.gov (United States)

    Lin, M.; Thiemens, M. H.; Shen, Y.; Zhang, X.; Huang, X.; Chen, K.; Zhang, Z.; Tao, J.

    2017-12-01

    The signature of sulfur isotopic mass-independent fractionation (S-MIF) observed in Archean sediments have been interpreted as a proxy of the origins and evolution of atmospheric oxygen and early life on Earth [1]. Photochemistry of SOx in the short (negative Δ36S. After eliminating combustion impacts, the obtained Δ36S/Δ33S slope of -4.0 in the modern atmosphere is close to the Δ36S/Δ33S slope (-3.6) in some records from Paleoarchean [4], an era probably with active volcanism [5]. The significant role of volcanic OCS in the Archean atmosphere has been called for in terms of its ability to provide a continual SO2 high altitude source for photolysis [2]. The strong but previously underappreciated stratospheric signature of S-MIF in tropospheric sulfates suggests that a more careful investigation of wavelength-dependent sulfur isotopic fractionation at different altitudes are required. The combustion-induced negative Δ36S may be linked to recombination reactions of elemental sulfur [6], and relevant experiments are being conducted to test the isotope effect. Although combustion is unlikely in Archean, recombination reactions may occur in other previously unappreciated processes such as volcanism and may contribute in part to the heavily depleted 36S in some Paleoarchean records [5,7]. The roles of both photochemical and non-photochemical reactions in the variability of Archean S-MIF records require further analysis in the future. Refs: [1] Farquhar et al., Science 2000; [2] Shaheen et al., PNAS 2014; [3] Lin et al., PNAS 2016; [4] Wacey et al., Precambrian Res 2015; [5] Muller et al., PNAS 2016; [6] Babikov, PNAS 2017; [7] Shen et al., EPSL, 2009.

  17. The Strontium Isotope Record of Zavkhan Terrane Carbonates: Strontium Isotope Stability Through the Ediacaran-Cambrian Transition

    OpenAIRE

    Petach, Tanya N.

    2015-01-01

    First order trends in the strontium isotopic (87Sr/86Sr) composition of seawater are controlled by radiogenic inputs from the continent and non-radiogenic inputs from exchange at mid-ocean ridges. Carbonates precipitated in seawater preserve trace amounts of strontium that record this isotope ratio and therefore record the relative importance of mid-ocean ridge and weathering chemical inputs to sea water composition. It has been proposed that environmental changes during the Ediacaran-Cambria...

  18. 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...

  19. Lake Baikal isotope records of Holocene Central Asian precipitation

    Science.gov (United States)

    Swann, George E. A.; Mackay, Anson W.; Vologina, Elena; Jones, Matthew D.; Panizzo, Virginia N.; Leng, Melanie J.; Sloane, Hilary J.; Snelling, Andrea M.; Sturm, Michael

    2018-06-01

    Climate models currently provide conflicting predictions of future climate change across Central Asia. With concern over the potential for a change in water availability to impact communities and ecosystems across the region, an understanding of historical trends in precipitation is required to aid model development and assess the vulnerability of the region to future changes in the hydroclimate. Here we present a record from Lake Baikal, located in the southern Siberian region of central Asia close to the Mongolian border, which demonstrates a relationship between the oxygen isotope composition of diatom silica (δ18Odiatom) and precipitation to the region over the 20th and 21st Century. From this, we suggest that annual rates of precipitation in recent times are at their lowest for the past 10,000 years and identify significant long-term variations in precipitation throughout the early to late Holocene interval. Based on comparisons to other regional records, these trends are suggested to reflect conditions across the wider Central Asian region around Lake Baikal and highlight the potential for further changes in precipitation with future climate change.

  20. Evaluating the use of strontium isotopes in tree rings to record the isotopic signal of dust deposited on the Wasatch Mountains

    International Nuclear Information System (INIS)

    Miller, Olivia L.; Solomon, Douglas Kip; Fernandez, Diego P.; Cerling, Thure E.; Bowling, David R.

    2014-01-01

    Highlights: • Dust was a major contributor of Sr to soil and tree rings over Sr poor bedrocks. • Tree rings were evaluated for their use as a record of dust strontium isotope history. • The isotopic signal of dust deposited on the Wasatch Mountains changed over the past ∼75 years. - Abstract: Dust cycling from the Great Basin to the Rocky Mountains is an important component of ecological and hydrological processes. We investigated the use of strontium (Sr) concentrations and isotope ratios ( 87 Sr/ 86 Sr) in tree rings as a proxy for dust deposition. We report Sr concentrations and isotope ratios ( 87 Sr/ 86 Sr) from atmospherically deposited dust, soil, bedrock, and tree rings from the Wasatch Mountains to investigate provenance of dust landing on the Wasatch Mountains and to determine if a dust Sr record is preserved in tree rings. Trees obtained a majority of their Sr from dust, making them a useful record of dust source and deposition. Dust contributions of Sr to soils were more than 94% over quartzite, 63% over granodiorite, and 50% over limestone. Dust contributions of Sr to trees were more than 85% in trees growing over quartzite, 55% over granodiorite, and between 0% and 92% over limestone. These findings demonstrate that a dust signal was preserved in some tree rings and reflects how Sr from dust and bedrock mixes within the soil. Trees growing over quartzite were most sensitive to dust. Changes in Sr isotope ratios for a tree growing over quartzite were interpreted as changes in dust source over time. This work has laid the foundation for using tree rings as a proxy for dust deposition over time

  1. Isotopic evidence for multiple contributions to felsic magma chambers

    DEFF Research Database (Denmark)

    Waight, Tod Earle; Wiebe, R.A.; Krogstad, E.J.

    2007-01-01

    The Gouldsboro Granite forms part of the Coastal Maine Magmatic Province, a region characterized by granitic plutons that are intimately linked temporally and petrogenetically with abundant co-existing mafic magmas. The pluton is complex and preserves a felsic magma chamber underlain...... with identical isotopic compositions to more mafic dikes suggest that closed system fractionation may be occurring in deeper level chambers prior to injection to shallower levels. The granitic portion of the pluton has the highest Nd isotopic composition (eNd=+3.0) of plutons in the region whereas the mafic...

  2. Interrogating trees for isotopic archives of atmospheric sulphur deposition and comparison to speleothem records

    International Nuclear Information System (INIS)

    Wynn, P.M.; Loader, N.J.; Fairchild, I.J.

    2014-01-01

    Palaeorecords which depict changes in sulphur dynamics form an invaluable resource for recording atmospheric pollution. Tree rings constitute an archive that are ubiquitously available and can be absolutely dated, providing the potential to explore local- to regional-scale trends in sulphur availability. Rapid isotopic analysis by a novel “on-line” method using elemental analyser isotope ratio mass spectrometry (EA-IRMS) is developed, achieving sample precision of <0.4‰ using sample sizes of 40 mg wood powder. Tree cores from NE Italy show trends in pollution, evidenced through increasing concentrations of sulphur towards the youngest growth, and inverse trends in sulphur isotopes differentiating modern growth with light sulphur isotopes (+0.7‰) from pre-industrial growth (+7.5‰) influenced by bedrock composition. Comparison with speleothem records from the same location demonstrate replication, albeit offset in isotopic value due to groundwater storage. Using EA-IRMS, tree ring archives form a valuable resource for understanding local- to regional-scale sulphur pollution dynamics. - Highlights: • Sulphur isotopes from tree rings are analysed using ‘on-line’ EA combustion. • Isotopes differentiate modern growth influenced by pollution from pre-industrial growth. • Biogeochemical cycling imparts minimal delay in sulphur incorporation into tree rings. • Trends in pollution are replicated between speleothems and trees from the same location. - Sulphur isotopes extracted from tree ring records are used to identify twentieth century pollution dynamics at the local- to regional-scale

  3. Contribution of Isotopic Tools to the Numerical Simulation of the Mar del Plata Coastal Aquifer, Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Bocanegra, E.; Martinez, D. E. [Instituto de Geologia de Costas y del Cuaternario, UNMDP (Argentina); Pool, M.; Carrera, J. [Instituto de Diagnostico Ambiental y Estudios del Agua, CSIC (Spain)

    2013-07-15

    Over-exploitation in the coastal aquifer in Mar del Plata, Argentina, led to a seawater intrusion process affecting groundwater by salinization. The aim of this paper is to show the contribution of isotopic techniques to generate the numerical flow and transport model of the Mar del Plata aquifer. On the basis of the hydrogeological conceptual model, a numerical model was constructed. It consists of a multilayer aquifer in the urban area with 2 layers separated by an aquitard and a monolayer aquifer in the rest of the basin. The isotopic difference recorded in groundwaters allow the identification of the origin of the recharge and the confirmation of the presence of the hydrogeological environments incorporated in the numerical model. Flow simulation reflects the evolution of piezometric heads. Chloride transport simulation represents the salinization process due to seawater intrusion and the subsequent backward movement of the interface due to the abandonment of salinized wells. The results of numerical simulation confirm the conceptual model and reproduce the impact of the adopted management strategies. (author)

  4. Contribution of isotopic data in cerebrospinal fluid (CSF) studies

    International Nuclear Information System (INIS)

    Askienazy, S.; Ducassou, D.

    The growing interest in isotopic CSF studies is explained by the fact that the mechanism and classification of hydrocephalus cases are based not only on anatomoclinical data but also on physiological information inaccessible by static image methods. This article shows the full importance of dynamic CSF research (ideal tracer: 111 In-DTPA); the possibilities of myeloscintigraphy to study the permeability of the medullary sub-arachnoid spaces (tracers used: sup(99m)Tc-DTPA in the liquid phase or xenon bubble technique in the gas phase); ventricular morphology; existence of meningeal gaps [fr

  5. Stable and strontium isotopic records of molluscan shells, lower jurassic, Cuenca Neuquina, southwestern Mendoza, Argentina

    International Nuclear Information System (INIS)

    Cagnoni, M.C.; Valencio, S.A.; Ramos, A.M; Riccardi, A.C; Panarello, H.O

    2001-01-01

    The strontium, carbon and oxygen isotopic signal of the past oceans is accurately recorded by authigenic marine minerals such as carbonates, sulfates and phosphates. The variation of these isotope ratios through the geological time is used as a tool in correlating and dating marine sedimentary rocks. Many works have been done concerning to the changes in carbon, oxygen and strontium isotope ratios of different marine successions in the world. These allow the construction of curves of secular variations of the isotope signals with geological time (Jones et al., 1994a, 1994b; Veizer et al., 1999; Jacobsen and Kaufman, 1999). This work presents strontium, carbon and oxygen isotope ratios of Early Jurassic biogenic marine carbonates of Cuenca Neuquina in southwestern Mendoza (au)

  6. Historical record of lead accumulation and source in the tidal flat of Haizhou Bay, Yellow Sea: Insights from lead isotopes

    International Nuclear Information System (INIS)

    Zhang, Rui; Guan, Minglei; Shu, Yujie; Shen, Liya; Chen, Xixi; Zhang, Fan; Li, Tiegang

    2016-01-01

    In order to investigate the historical records of lead contamination and source in coastal region of Haizhou Bay, Yellow Sea, a sediment core was collected from tidal flat, dated by 210 Pb and 137 Cs. Lead and its stable isotopic ratios were determined. The profiles of enrichment factor (EF) and Pb isotope ratios showed increasing trend upward throughout the core, correlating closely with the experience of a rapid economic and industrial development of the catchment. According to Pb isotopic ratios, coal combustion emission mainly contributed to the Pb burden in sediments. Based on end-member model, coal combustion emission dominated anthropogenic Pb sources in recent decades contributing from 48% to 67% in sediment. And the contribution of leaded gasoline was lower than 20%. A stable increase of coal combustion source was found in sediment core, while the contribution of leaded gasoline had declined recently, with the phase-out of leaded gasoline in China. - Highlights: •Pb contamination in tidal flat of Haizhou Bay was chronicled by a sediment core. •The coal combustion source dominated Pb contamination of Haizhou Bay. •Coal combustion source showed an increasing trend in four decades in Haizhou Bay.

  7. Oxygen Isotope Records in Modern Oyster Shells from Chi Ku, Tainan and Their Implication of Seasonality

    Science.gov (United States)

    Chen, Y. C.; Mii, H. S.; Li, K. T.

    2015-12-01

    To exam whether oxygen isotope records of Crassostrea gigasoysters can be used as proxies of environment, 133 cultivated oysters and 21 water samples were collected from Chi Ku area, Tainan City, southern Taiwan in December of 2012, and from March, 2013 to July, 2014. Instrumental air and water temperatures and precipitation records were obtained from a nearest Central Weather Bureau (CWB) station roughly 16 km north of Chi Ku. The oxygen and carbon isotope values of the ligamental area of the modern oyster shells are from -6.92‰ to -0.08‰ (-3.05 ± 1.17‰, N = 2280; 1σ; VPDB) and from -5.57‰ to 0.63‰ (-1.88 ± 0.81‰), respectively. Oxygen isotope values of the water samples are mainly between -0.28‰ and 0.74‰ (0.18 ± 0.29‰, N = 20; 1σ; VSMOW). However, water oxygen isotope value of -2.75‰ was observed for the water sample collected immediately after a typhoon heavy rainfall. Seasonal temperature fluctuation pattern of estimated oxygen isotope temperatures from modern shells is similar to that of CWB instrumental records. However, the oxygen isotope temperatures are respectively about 3 °C and 10°C higher than those of instrumental records for winter and summer. Higher estimated oxygen isotope temperatures are most likely caused by underestimated fraction of freshwater. We analyzed 5 archaeological oyster shells of Siraya culture (500~250B.P.) collected from Wu Chien Tuso North (WCTN) archaeological site of Tainan branch of Southern Taiwan Science Park to infer the harvest season of mollusks. Oxygen isotope values of the ligamental area of the archaeological oyster shells are between -5.98‰ and -1.26‰ (-3.34 ± 1.37‰, N = 60; 1σ), and carbon isotope values are between -3.21‰ and 0.60‰ (-2.04‰ ± 0.55‰). The oxygen isotope records of archaeological oyster shells also showed clear seasonality. Most of the oysters were collected in autumn and winter. Oxygen isotope values of archaeological oyster shells was 1‰ greater than that

  8. Stable isotopes and their relationship to temperature and precipitation as recorded in low latitude ice cores

    International Nuclear Information System (INIS)

    Thompson, L.G.; Davis, M.E.; Pin-Nan, Lin

    2002-01-01

    The potential of stable isotopic ratios ( 18 O/ 16 O and 2 H/ 1 H) in mid to low latitude glaciers as modern tools for paleoclimate reconstruction is reviewed. The isotopic composition of precipitation should be viewed not only as a powerful proxy indicator of climate, but also as an additional parameter for understanding climate-induced changes in the water cycle, on both regional and global scales. To interpret quantitatively the ice core isotopic records, the response of the isotopic composition of precipitation to long-term fluctuations of key climatic parameters (temperature, precipitation amount, relative humidity) over a given area should be known. Furthermore, it is important to establish the transfer functions that relate the climate-induced changes of the isotopic composition of precipitation to the isotope record preserved in the glacier. The factors that govern the values of stable isotopes in snowfall are enigmatic and as yet no satisfactory model has been developed to link them directly with any one meteorological or oceanographic factor. This is particularly problematic in the high altitude glaciers in the tropics, where complications are present due not only to continental effects, but also to altitude effects and convective air mass instability, particularly in the monsoon climates of the tropics. This paper presents long and short-term perspectives of isotopic composition variations in ice cores spanning the last 25,000 years from the mid- to low-latitude glaciers. The isotopic records will also be examined as a function of the altitude of the individual coring sites which ranges from 5325 meters to 7200 meters. On the short, term isotopic records from ice cores from the Andes of South America, the Tibetan Plateau and Kilimanjaro in Africa through the year 2000 will be presented. All the tropical glaciers for which data exist are disappearing, and these sites show isotopic enrichment in the 20th century that suggests that large scale low latitude

  9. Contribution to optimisation of Environmental Isotopes tracing in Hydrogeology. Case study of Madagascar

    International Nuclear Information System (INIS)

    RAJAOBELISON, J.

    2003-01-01

    The aim of this work is to suggest some improvements on the theory of interpretation and on the methodological approach for the optimum use of environmental isotopes tracing applied to hydrogeological investigation. A review of the theory of environmental isotopes used in hydrogeology has been made. The main constraints have been highlighted and led to some comments and proposals of improvement, in particular with regard to the continental effect on stable isotopes, to the seasonal variation of groundwater 1 4C content, and to the appropriate model for fractured crystalline aquifers. A literature survey on ten specific scientific papers, dealing with isotopic hydrology in miscellaneous types of aquifers and catchments, allowed to draw a synthesis of the hydrogeological, geochemical and isotopic constraints. A proposal of optimum methodological approach, taking into account the above mentioned constraints, have been inferred. The results of an on-going hydrogeological investigation carried out in the Southern crystalline basement and coastal sedimentary aquifers of Madagascar highlights an unusual methodological approach based on the lack of initial basic hydrogeological data. Besides, it shows to what extent the experience of the above mentioned research works can apply in the specific case of the complex aquifers of Madagascar. The lessons gained from this study contribute to enrich the synthesis of environmental isotopes constraints in hydrogeology and lead to a more realistic methodological approach proposal wich is likely to better make profitable the isotope hydrology technology

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

    Science.gov (United States)

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

    2014-12-01

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

  11. Eocene to Oligocene benthic foraminiferal isotopic record in the Bay of Biscay

    International Nuclear Information System (INIS)

    Miller, K.G.; Curry, W.B.

    1982-01-01

    Oxygen and carbon isotopic records of Eocene to Oligocene benthic foraminifera from two Bay of Biscay Deep Sea Drilling Project sites are presented. The delta 18 O figures for benthic foraminifera are significantly higher than those previously reported from deeper North Atlantic sites, the differences arising it is believed from diagenetic alteration of the sediments in the deeper-buried sites. (U.K.)

  12. U-series dating and stable isotope records of speleothem records from the Scladina Cave (Belgium)

    Science.gov (United States)

    van der Lubbe, Jeroen; Bonjean, Dominique; Hellstrom, John; Verheyden, Sophie; Vonhof, Hubert

    2015-04-01

    The Scladina cave, situated in the village of Sclayn (Ardennes, Belgium) at the southern bank of the Meuse, is famous for its Neanderthal fossils and artefacts. The infilling of the cave consists of a succession of flowstone layers interbedded with reworked loess sediment from outside the cave. The younger flowstone layers correspond to interglacials MIS 5 and the Holocene, while the reworked loess sediments represent cooler conditions. By careful diagenetic screening, well-preserved speleothem material was selected for U-series dating and stable isotope analysis of calcite and fluid inclusions. The results provide important new constraints on the age of Neanderthal fossils and artefacts, and bracket the time periods with a hydroclimate favorable for speleothem growth. The combination of fluid inclusion and calcite isotope analysis documents climate variability in the interglacials at high temporal resolution.

  13. Chromium isotope record of the Otavi Group, Namibia

    DEFF Research Database (Denmark)

    Rodler, Alexandra; Frei, Robert; Gaucher, Claudio

    2013-01-01

    -Triassic (~252 Ma) boundaries, which coincide with Central Atlantic Magmatic Province (CAMP) and Siberian Trap volcanism, respectively. The Triassic-Jurassic mass extinction is often contributed to carbon release driven ocean acidification while the Permian-Triassic mass extinction is suggested to be related...... to widespread ocean anoxia. We compare Permian-Triassic and Triassic-Jurassic ocean redox change along continental margins in different geographic regions (Permian-Triassic: Greenland, Svalbard, Iran; Triassic-Jurassic: UK, Austria) and discuss its role in marine mass extinction. Speciation of iron [(FeHR/ Fe...... extinctions however shows 2 phases of euxinia along continental margins, with an initial short peak at the onset of volcanism followed by a shift to ferruginous conditions, possibly due to a strongly diminished ocean sulphate reservoir because of massive initial pyrite burial. D34Spyrite suggests...

  14. Decade to centennial resolution hydrogen isotopic record of climate change from southern New England for the past 16 kyr: proxy validation and multi-proxy comparisons

    Science.gov (United States)

    Huang, Y.; Gao, L.; Hou, J.; Shuman, B. N.; Oswald, W.; Foster, D.

    2009-12-01

    Open system lakes in New England offer excellent archives of precipitation isotopic ratios that yield quantitative paleoclimate information. We have demonstrated previously from a lake sediment transect that hydrogen isotopic ratios of a middle-chain length fatty acid, behenic acid (BA), faithfully record precipitation isotopic ratios. We hypothesized that mid-chain n-alkyl lipids in these small lakes were primarily derived from aquatic plants that record lake water isotopic ratios. To test this hypothesis, we conducted systematic and extensive sampling of both terrestrial and aquatic plants over the past two years at two typical kettle hole lakes, Blood Pond and Rocky Pond, MA, and used a linear algebra approach to delineate percentage inputs of aquatic and terrestrial plant contributions to mid-chain n-alkyl lipids. Our results demonstrate that >92 % of the mid-chain n-alkyl lipids is derived from submerged and floating aquatic macrophytes. Our new data provide a solid basis for the application of behenic hydrogen isotopic ratios as a paleoclimate proxy from small lakes. We will present a decadal to centennial scale 16 kyr record of BA hydrogen isotopic ratios from Blood Pond, and will discuss the results in light of published pollen and lake level data. Overall, our hydrogen isotopic record is fully consistent with regional climate scenarios, including the distinctive warming at B-A events, abrupt cooling at YD event, and transition from glacial to Holcoene climate conditions. However, our high-solution isotopic data provides important new insights concerning abrupt regional climate variability. We demonstrate that the New England climate is exceptionally senstive to AMOC changes and solar forcing and that many of the abrupt climate fluctuations exert major impacts on terrestrial ecosystems, hydrology and lake levels.

  15. Coordinated Oxygen Isotopic and Petrologic Studies of CAIS Record Varying Composition of Protosolar

    Science.gov (United States)

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

    2012-01-01

    Ca-, Al-rich inclusions (CAIs) record the O-isotope composition of Solar nebular gas from which they grew [1]. High spatial resolution O-isotope measurements afforded by ion microprobe analysis across the rims and margin of CAIs reveal systematic variations in (Delta)O-17 and suggest formation from a diversity of nebular environments [2-4]. This heterogeneity has been explained by isotopic mixing between the O-16-rich Solar reservoir [6] and a second O-16-poor reservoir (probably nebular gas) with a "planetary-like" isotopic composition [e.g., 1, 6-7], but the mechanism and location(s) where these events occur within the protoplanetary disk remain uncertain. The orientation of large and systematic variations in (Delta)O-17 reported by [3] for a compact Type A CAI from the Efremovka reduced CV3 chondrite differs dramatically from reports by [4] of a similar CAI, A37 from the Allende oxidized CV3 chondrite. Both studies conclude that CAIs were exposed to distinct, nebular O-isotope reservoirs, implying the transfer of CAIs among different settings within the protoplanetary disk [4]. To test this hypothesis further and the extent of intra-CAI O-isotopic variation, a pristine compact Type A CAI, Ef-1 from Efremovka, and a Type B2 CAI, TS4 from Allende were studied. Our new results are equally intriguing because, collectively, O-isotopic zoning patterns in the CAIs indicate a progressive and cyclic record. The results imply that CAIs were commonly exposed to multiple environments of distinct gas during their formation. Numerical models help constrain conditions and duration of these events.

  16. Reconstruction of three centuries of annual accumulation rates based on the record of stable isotopes of water from Lomonosovfonna, Svalbard

    NARCIS (Netherlands)

    Pohjola, V.; Martma, T.; Meijer, H.A.J.; Moore, J.; Isaksson, E.; Vaikmae, R.; van de Wal, R.S.W.

    2002-01-01

    We use the upper 81 in of the record of stable isotopes of water from a 122 in long ice core from Lomonosovfonna, central Spitsbergen, Svalbard, to construct an ice-core chronology and the annual accumulation rates over the icefield. The isotope cycles are counted in the ice-core record using a

  17. Estimation of pollutant source contribution to the Pampanga River Basin using carbon and nitrogen isotopes

    International Nuclear Information System (INIS)

    Castaneda, Solidad S.; Sta Maria, Efren J.; Ramirez, Jennyvi D.; Collado, Mario B.; Samar, Edna D.

    2013-01-01

    This study assessed and estimated the percentage contribution of potential pollution sources in Pampanga River Basin using carbon and nitrogen isotopes as environmental tracers. The δ 13 C and δ 15 N values were determined in particulate organic matter, surface sediment, and plant tissue samples from point and non-point sources from several land use areas, namely domestic, croplands, livestock, fishery and forestry. Investigations were conducted in the wet and dry seasons (2012 and 2013). Some N sources do not have unique δ 15 N and there is overlapping among different N- sources type. δ 13 C data from the N sources provided an additional dimension which distinguished animal manure, human waste (septic and sewage), leaf litter, and synthetic fertilizer. Characterization of the non-point N-sources based on the isotopic fingerprints obtained from the point sources revealed that domestic, cropland, livestock, and fishery, influenced the isotopic composition of the materials but domestic and cropland land use provided the most significant influence. Livestock also contributed to a lesser extent. Isotope mixing model revealed that cropland sources generally contributed the most to pollutant loading during the wet season, from 22% to 98%, while domestic waste contributed higher in the dry season, from 55% to 65%. (author)

  18. Assessment of diffusive isotopic fractionation in polar firn, and application to ice core trace gas records

    DEFF Research Database (Denmark)

    Buizert, C.; Sowers, T.; Blunier, T.

    2013-01-01

    During rapid variations of the atmospheric mixing ratio of a trace gas, diffusive transport in the porous firn layer atop ice sheets and glaciers alters the isotopic composition of that gas relative to the overlying atmosphere. Records of past atmospheric trace gas isotopic composition from ice...... cores and firn need to be corrected for this diffusive fractionation artifact. We present a novel, semi-empirical method to accurately estimate the magnitude of the diffusive fractionation in the ice core record. Our method (1) consists of a relatively simple analytical calculation; (2) requires only...... commonly available ice core data; (3) is not subject to the uncertainties inherent to estimating the accumulation rate, temperature, close-off depth and depth-diffusivity relationship back in time; (4) does not require knowledge of the true atmospheric variations, but uses the smoothed records obtained...

  19. 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

  20. Late Glacial Tropical Savannas in Sundaland Inferred From Stable Carbon Isotope Records of Cave Guano

    Science.gov (United States)

    Wurster, C. M.; Bird, M. I.; Bull, I.; Dungait, J.; Bryant, C. L.; Ertunç, T.; Hunt, C.; Lewis, H. A.; Paz, V.

    2008-12-01

    During the Last Glacial Period (LGP), reduced global sea level exposed the continental shelf south of Thailand to Sumatra, Java, and Borneo to form the contiguous continent of Sundaland. However, the type and extent of vegetation that existed on much of this exposed landmass during the LGP remains speculative. Extensive bird and bat guano deposits in caves throughout this region span beyond 40,000 yr BP, and contain a wealth of untapped stratigraphic palaeoenvironmental information. Stable carbon isotope ratios of insectivorous bird and bat guano contain a reliable record of the animal's diet and, through non-specific insect predation, reflect the relative abundance of major physiological pathways in plants. Various physiological pathways of carbon fixation in plants yield differing stable carbon isotope ratios. Stable carbon isotope values of C3 plants are lower than C4 vegetation due to different enzymatic discriminations of the heavy isotope through the carbon fixing pathways. In tropical locales, grasses nearly always follow the C4 photosynthetic pathway, whereas tropical rainforest uses C3 photosynthesis, providing a proxy for vegetation and therefore climate change in the past. Here we discuss four guano stable-isotope records, based on insect cuticle and n-alkane analysis, supplemented by pollen analysis. All sites suggest a C3 dominated ecosystem for the Holocene, consistent with the wet tropical forest vegetation present at all locations. Two sites from Palawan Island, Philippines, record stable carbon isotope values of guano that document a drastic change from C3 (forest) to C4 (savanna) dominated ecosystems during the Last Glacial Maximum (LGM). A third location, at Niah Great Cave, Malaysia, indicates C3-dominant vegetation throughout the record, but does display variation in stable carbon isotope values likely linked to humidity changes. A fourth location, Batu Caves in Peninsular Malaysia, also indicates open vegetation during the LGM. Vegetation

  1. The Pb isotopic record of historical to modern human lead exposure

    International Nuclear Information System (INIS)

    Kamenov, George D.; Gulson, Brian L.

    2014-01-01

    Human teeth and bones incorporate trace amounts of lead (Pb) from the local environment during growth and remodeling. Anthropogenic activities have caused changes in the natural Pb isotopic background since historical times and this is reflected in the Pb isotopes of historical European teeth. Lead mining and use increased exponentially during the last century and the isotopic compositions of modern human teeth reflect the modern anthropogenic Pb. USA teeth show the most radiogenic Pb and Australian teeth show the least radiogenic Pb, a result of different Pb ores used in the two regions. During the last century the Australian Pb was exported to Europe, Asia, South America, and Africa, resulting in swamping of the local environmental Pb signal by the imported Pb. As a result, the modern human teeth in Europe show a significant drop to lower isotopic values compared with historical times. Similarly, modern human teeth in other regions of the world show similar Pb isotopic ratios to modern European teeth reflecting the Pb imports. The specific pattern of human Pb exposure allows us to use the Pb isotopic signal recorded in the skeleton as a geo-referencing tool. As historical European teeth show a distinct Pb signal, we can identify early European skeletal remains in the New World and likely elsewhere. In modern forensic investigations we can discriminate to some extent Eastern Europeans from Western and Northern Europeans. Australians can be identified to some extent in any region in the world, although there is some overlap with Western European individuals. Lead isotopes can be used to easily identify foreigners in the USA, as modern USA teeth are distinct from any other region of the world. By analogy, USA individuals can be identified virtually in any other region of the world. - Highlights: • We present high-precision Pb isotope data for historical and modern human teeth. • Human teeth reflect human Pb exposure since historical times. • Modern teeth show

  2. The Pb isotopic record of historical to modern human lead exposure

    Energy Technology Data Exchange (ETDEWEB)

    Kamenov, George D., E-mail: kamenov@ufl.edu [Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL 32611 (United States); Gulson, Brian L. [Graduate School of the Environment, Faculty of Science, Macquarie University, Sydney, NSW 2109 (Australia)

    2014-08-15

    Human teeth and bones incorporate trace amounts of lead (Pb) from the local environment during growth and remodeling. Anthropogenic activities have caused changes in the natural Pb isotopic background since historical times and this is reflected in the Pb isotopes of historical European teeth. Lead mining and use increased exponentially during the last century and the isotopic compositions of modern human teeth reflect the modern anthropogenic Pb. USA teeth show the most radiogenic Pb and Australian teeth show the least radiogenic Pb, a result of different Pb ores used in the two regions. During the last century the Australian Pb was exported to Europe, Asia, South America, and Africa, resulting in swamping of the local environmental Pb signal by the imported Pb. As a result, the modern human teeth in Europe show a significant drop to lower isotopic values compared with historical times. Similarly, modern human teeth in other regions of the world show similar Pb isotopic ratios to modern European teeth reflecting the Pb imports. The specific pattern of human Pb exposure allows us to use the Pb isotopic signal recorded in the skeleton as a geo-referencing tool. As historical European teeth show a distinct Pb signal, we can identify early European skeletal remains in the New World and likely elsewhere. In modern forensic investigations we can discriminate to some extent Eastern Europeans from Western and Northern Europeans. Australians can be identified to some extent in any region in the world, although there is some overlap with Western European individuals. Lead isotopes can be used to easily identify foreigners in the USA, as modern USA teeth are distinct from any other region of the world. By analogy, USA individuals can be identified virtually in any other region of the world. - Highlights: • We present high-precision Pb isotope data for historical and modern human teeth. • Human teeth reflect human Pb exposure since historical times. • Modern teeth show

  3. Foraminifera isotopic records... with special attention to high northern latitudes and the impact of sea-ice distillation processes

    Energy Technology Data Exchange (ETDEWEB)

    Hillaire-Marcel, Claude, E-mail: hillaire-marcel.claude@uqam.ca [GEOTOP, Universite du Quebec a Montreal, PO Box 8888, succursale ' centre ville' Montreal, Qc, H3C 3P8 (Canada)

    2011-05-15

    Since the reassessment of oxygen isotope paleotemperatures by N. Shackleton in the late 60s, most papers using isotopic records from planktic or benthic foraminifers imply a direct relationship between oxygen isotopes in seawater and the ice/ocean volume, thus some linkage with salinity, sea level, etc. Such assumptions are also made when incorporating 'isotopic modules' in coupled models. Here, we will further examine the linkages between salinity and oxygen isotope ratios of sea-water recorded by foraminifers, and their potential temporal and spatial variability, especially in the northern North Atlantic and the Arctic oceans. If temporal and spatial changes in the isotopic composition of precipitations and ice meltwaters tune the isotopic properties of the fresh water end-member that dilutes the ocean, rates of sea-ice formation and evaporation at the ocean surface play a further role on the salt and oxygen isotope contents of water masses. Thus, the oxygen 18-salinity relationship carries a specific isotopic signature for any given water mass. At the ocean scale, residence time and mixing of these water masses, as well as the time dependent-achievement of proxy-tracer equilibrium, will also result in variable recordings of mass transfers into the hydrosphere, notable between ice-sheets and ocean. Since these records in water mass may vary in both amplitude and time, direct correlations of isotopic records will potentially be misleading. Implications of such issues on the interpretation of oxygen isotope records from the sub-arctic seas will be discussed, as well as the inherent flaws of such records due to sedimentological and or ecological parameters.

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

    Science.gov (United States)

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

    2014-01-01

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

  5. Contributions of isotopic bio-geochemistry to the analysis of water - soil - root interactions

    International Nuclear Information System (INIS)

    Cayet, S.

    2001-07-01

    The aim of this work is to study the origin of the isotopic signal of the water produced by plants transpiration. It stresses more particularly on the water movements between the soil and the plant in a context of heterogenous water availability for the root system. The use of water isotopes ( 18 O and 2 H) should allow to precise the water extraction depth of the roots and the plant strategy in front of a hydric stress of edaphic origin. The first chapter presents the place of water in the soil-plant-atmosphere continuum, the different potential sources of water accessible to the plant, the principles of water absorption and the hydric transfer in the plant in relation with the variations of water absorption and of the evaporative conditions. The isotopic method is introduced with the natural variability of the isotopic composition of the atmospheric and soil waters. Finally, the reaction of the plant in front of a hydric stress is described. The second chapter presents a series of experiments carried out in the natural environment and shows the problems encountered during the determination of water origin in heterogenous hydric availability conditions. The third chapter describes the experiments performed in controlled environment. One series of experiments is performed in homogenous hydric availability condition. The aim is to analyze the isotopic signal emitted by the plant and its significance with respect to the feeding water. The second series of experiments is performed in heterogenous hydric availability conditions and in stable or variable climatic conditions. In the last chapter, the different experiments performed in natural environment are presented, first in optimum hydric availability conditions, and second in variable hydric conditions. These experiments allow to reconstruct the isotopic signal of the soil water which is recorded by the plant and to precise the preferential areas of water extraction by the roots, and the competitive behaviour of

  6. Links between meteorological conditions and spatial/temporal variations in long-term isotope records from the Austrian precipitation network

    International Nuclear Information System (INIS)

    Kaiser, A.; Scheifinger, H.; Kralik, M.; Papesch, W.; Rank, D.; Stichler, W.

    2002-01-01

    The isotope records from the Austrian Network for Isotopes in Precipitation (ANIP) show significant but not uniform long-term trends. While the 10-year running means of some mountain stations exhibit a pronounced increase in δ 18 O of about 1 per mille since 1975, the change of δ 18 O at the valley stations is much lower. There are also differences in the time behaviour. The differences in the δ 18 O-values of sampling stations at similar altitudes can be explained by different origins of the air moisture (Atlantic or Mediterranean influence). Furthermore, a significant difference in the behaviour of the deuterium excess at neighbouring mountain and valley stations has been observed. There is a slight increase of the yearly mean of the deuterium excess with increasing altitude of the sampling station. But moreover, the seasonal pattern of the deuterium excess is quite different. While the valley stations exhibit the expected minimum in summer, the mountain stations show a distinct maximum between June and October. As a first step into a comprehensive analysis of the meteorological effects on the isotope patterns, the role of advection of different air masses is studied by trajectory statistics. Back trajectories, based on the three dimensional wind fields of the ECMWF model, are calculated for each hour within each precipitation event. Thus, the frequency of the origin of air masses and their contribution to the isotope patterns of the monthly precipitation samples are studied for two selected mountain stations north and south of the main ridge of the Alps. (author)

  7. Climatic correlations in the stable isotope records of silver fir (Abies pindrow) trees from Kashmir, India

    International Nuclear Information System (INIS)

    Ramesh, R.; Bhattacharya, S.K.; Gopalan, K.

    1986-01-01

    A high degree of coherence in the annual stable isotopic records along different radial directions of a silver fir tree and between two members of this species from the Kashmir Valley has recently been reported by us. Since such a common pattern of isotopic variability is most likely due to the climatic fluctuations in the site, we have compared the mean δD, δ 13 C and δ 18 O records of these trees with instrumentally measured climatic parameters recorded in a nearby weather station to identify the climatic parameters predominantly influencing the isotopic record. A multiple regression analysis of the two records for the period 1903-1932 yields the following: δD is most sensitive to the amount of growing season precipitation, followed by mean maximum temperature. Tree cellulose shows an amount effect analogous to precipitation samples. The temperature coefficient for δD is in good agreement with earlier estimates based on spatial correlations. δ 13 C is significantly related to humidity and cloud amount. The signs of the regression coefficients are consistent with the recent model of Francey and Farquhar for 13 C/ 12 C fractionation in C 3 plants. δ 18 O of cellulose appears to be controlled significantly by relative humidity. δ 18 O shows less overall correlation with climatic parameters than δD and δ 13 C. δD of carbon bound hydrogen and δ 18 O of tree cellulose are linearly related with a slope of 7.9±0.3, suggesting evaporative enrichment in leaf water. (orig.)

  8. Multiple Nebular Gas Reservoirs Recorded by Oxygen Isotope Variation in a Spinel-Rich CAI in CO3 MIL 090019

    Science.gov (United States)

    Simon, J. I.; Simon, S. B.; Nguyen, A. N.; Ross, D. K.; Messenger, S.

    2017-07-01

    We conducted NanoSIMS ion imaging studies of a primitive spinel-rich CAI from the MIL 090019 CO3 chondrite. It records radial O-isotopic heterogeneity among multiple occurrences of the same mineral, reflecting distinct nebular O-isotopic reservoirs.

  9. A biomarker stable isotope record of late Quaternary climate and organic matter export in Southwestern Taiwan

    Science.gov (United States)

    Chang, Q.; Hren, M. T.; Lin, A. T.; Eley, Y.; Yu, S. W.; Harris, G.

    2017-12-01

    We present new leaf wax n-alkane hydrogen (δD) and carbon (δ13C) isotopic data from a 36-m-long core from off-shore southwestern Taiwan to evaluate late Quaternary changes in climate and the source of organic matter exported from the landscape. The core (MD178-3291) is located on the flank of the Gaoping Submarine Canyon that connects with the Gaoping river catchment in southwestern Taiwan. The sediment deposition in this core spans the last 26 kyr, providing a unique record of glacial-interglacial changes in organic matter export from the Taiwan orogen. The δD and δ13C both show a shift in isotopic compositions at 15 kyr, that coincides with the shift in planktonic foraminifera δ18O record from the same core as well as the global sea level. We therefore interpret this dominant shift as affected by the global glacial to interglacial transition. Following by this transition and through the interglacial period, both biomarker δD and δ13C data record fluctuations that we suggest result from short timescale changes in the distribution of organic inputs to the offshore site. This change in source is most likely caused by increases in storm and landslide frequency or intensity during warmer intervals. This interpretation is supported by terrestrial records that show an increase in landslides in the Gaoping catchment and evidence for enhanced rainfall intensity and a corresponding increase in the frequency of turbidity currents.

  10. Biosynthetic effects on the stable carbon isotopic compositions of agal lipids: Implications for deciphering the carbon isotopic biomarker record

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Schouten, S.; Klein Breteler, W.C.M.; Blokker, P.; Schogt, N.; Rijpstra, W.I.C.; Grice, K.; Baas, M.

    1998-01-01

    Thirteen species of algae covering an extensive range of classes were cultured and stable carbon isotopic compositions of their lipids were analysed in order to assess carbon isotopic fractionation effects during their biosynthesis. The fatty acids were found to have similar stable carbon isotopic

  11. Stable isotopes in fish eye lenses as potential recorders of trophic and geographic history.

    Directory of Open Access Journals (Sweden)

    Amy A Wallace

    Full Text Available We evaluated eye lenses as potential recorders of stable isotope histories in fish because they consist of metabolically inert optical proteins that are deposited in successive, concentric circles (laminae much like otolith circuli and tree rings. We conducted four different tests on lenses from red snapper, red grouper, gag, and white grunt. The first test was a low-resolution screening of multiple individuals (4-5 radial groups of laminae per lens, all species except white grunt. Along the radial axis, all individuals exhibited substantial isotopic variability. Red snapper individuals separated into two groups based on δ15N and gag separated into two groups based on δ13C. Two gag with the greatest variation were chosen for high-resolution temporal analysis using individual laminae from their second eye lenses. The first-order patterns from the high-resolution analysis generally mimicked patterns from the low-resolution screening of grouped laminae, yet the high-resolution plots revealed early-life details that were not apparent in the low-resolution screenings. For the third test, left- versus right-eye variation was compared using high-resolution methods. White grunt left- and right-eye radial isotopic patterns were almost identical for both δ13C and δ15N, suggesting the variations observed among individual fish were not artifacts. The final test evaluated intra-laminar variation; multiple samples were analyzed from different parts of the same lamina. Seven laminae from three individuals of two species were analyzed in this manner; variations among laminae were found to be much higher than variations within laminae. However, nominal intra-laminar variations were comparable to nominal differences between left and right lenses, suggesting intra-laminar variation established measurement precision. Eye lens isotopes appear to be useful for reconstructing the isotopic histories of individual fish; these histories can be compared with spatially

  12. Stable isotope ratios in freshwater mussel shells as high resolution recorders of riverine environmental variation

    Science.gov (United States)

    Kukolich, S.; Kendall, C.; Dettman, D. L.

    2017-12-01

    The geochemical record stored in growth increments of freshwater mussel shells reveals annual to sub-annual changes in environmental conditions during the lifetime of the organism. The carbon, nitrogen, and oxygen stable isotope composition of aragonite shells responds to changes in water chemistry, temperature, streamflow, turbidity, growth rate, size, age, and reproduction. The goals of this study are to determine how stable isotopes can be used to reconstruct the conditions in which the mussels lived and to illuminate any vital effects that might obscure the isotopic record of those conditions. Previous research has suggested that annual δ13C values decrease in older freshwater mussel shells due to lower growth rates and greater incorporation of dietary carbon into the shell with increasing age. However, a high-resolution, seasonal investigation of δ13C, δ15N, and δ18O as they relate to organism age has not yet been attempted in freshwater mussels. A total of 28 Unionid mussels of three different species were collected live in 2011 in the Tennessee River near Paducah, Kentucky, USA. In this study, we analyzed the shell nacre and external organic layers for stable carbon, nitrogen, and oxygen isotope ratios, focusing on growth bands formed between 2006 and 2011. We present a time series of shell δ13C, δ18O, and δ15N values with monthly resolution. We also compare the shell-derived geochemical time series to a time series of the δ13C and δ15N of particulate organic matter, δ13C of DIC, δ18OWater, and water temperature in which the mussels lived. Results show that environmental factors such as water temperature and primary productivity dominate shell chemistry while animal age has little or no effect.

  13. High-frequency paleoclimatic variability: a spectral analysis of the Vostok ice-core isotopic record

    Energy Technology Data Exchange (ETDEWEB)

    Yiou, P.; Genthon, C.; Jouzel, J.; Le Treut, H.; Lorius, C.; Ghil, M.; Korotkevich, Y.S.

    1988-01-01

    This paper uses a recently analysed isotopic record from an ice core drilled at the Soviet Antartic Station VOSTOK, representing a total time span of about 160,000 years. Results obtained show the existence of a significative climatic variability at the time scale of 10,000 years and below. The many spectral peaks appear to be approximate linear combination of a little number among them, a clear indication of the non linear nature of climate fluctuations at these ''short'' time scales.

  14. Multidecadal climate variability in Brazil's Nordeste during the last 3000 years based on speleothem isotope records

    Science.gov (United States)

    Novello, Valdir F.; Cruz, Francisco W.; Karmann, Ivo; Burns, Stephen J.; Stríkis, Nicolás M.; Vuille, Mathias; Cheng, Hai; Lawrence Edwards, R.; Santos, Roberto V.; Frigo, Everton; Barreto, Eline A. S.

    2012-12-01

    We present the first high resolution, approximately ∼4 years sample spacing, precipitation record from northeastern Brazil (hereafter referred to as ‘Nordeste’) covering the last ∼3000 yrs from 230Th-dated stalagmites oxygen isotope records. Our record shows abrupt fluctuations in rainfall tied to variations in the intensity of the South American summer monsoon (SASM), including the periods corresponding to the Little Ice Age (LIA), the Medieval Climate Anomaly (MCA) and an event around 2800 yr B.P. Unlike other monsoon records in southern tropical South America, dry conditions prevailed during the LIA in the Nordeste. Our record suggests that the region is currently undergoing drought conditions that are unprecedented over the past 3 millennia, rivaled only by the LIA period. Using spectral, wavelet and cross-wavelet analyses we show that changes in SASM activity in the region are mainly associated with variations of the Atlantic Multidecadal Oscillation (AMO) and to a lesser degree caused by fluctuations in tropical Pacific SST. Our record also shows a distinct periodicity around 210 years, which has been linked to solar variability.

  15. Compiled records of carbon isotopes in atmospheric CO2 for historical simulations in CMIP6

    Directory of Open Access Journals (Sweden)

    H. Graven

    2017-12-01

    Full Text Available The isotopic composition of carbon (Δ14C and δ13C in atmospheric CO2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14C and 13C in the ocean and terrestrial components of Earth system models (ESMs present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs' component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of Δ14C and δ13C in atmospheric CO2 for the historical period 1850–2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6 for models simulating carbon isotopes in the ocean or terrestrial biosphere. The data may also be useful for other carbon cycle modelling activities.

  16. Modern Deep-sea Sponges as Recorders of Bottom Water Silicon Isotopes

    Science.gov (United States)

    Hendry, K. R.; Georg, R. B.; Rickaby, R. E.; Robinson, L. F.; Halliday, A. N.

    2008-12-01

    Major zones of opal accumulation in the world oceans have experienced geographical shifts during the Cenozoic coincident with times of transition in oceanic circulation and climate. The global marine silica cycle is likely to respond to various large-scale changes including the distillation of Si and other nutrients in ocean basins; weathering and continental inputs; and biological productivity in surface waters. These processes could potentially be distinguished by their impact on the isotopic composition of dissolved silica in the world oceans. Although diatoms dominate uptake of silica in surface waters, box-modelling (de la Rocha and Bickle, 2005) suggests that sponges spicules have a greater potential to reflect whole ocean changes in the silica cycle, by recording deep-water silicon isotopes. Here, we introduce a new calibration study of modern deep- sea sponges collected on a transect cruise across the Drake Passage, in the Southern Ocean, from a range of depths and seawater silicic acid concentrations. Sponges were collected by benthic trawling, and dried immediately. The spicules were later isolated from cellular material and cleaned for surface contaminants, before dissolution and analysis by NuPlasma HR MC-ICP-MS in medium resolution mode. We discuss our preliminary data, the extent to which inter and intraspecies variations reflect environmental conditions, and the implications for palaeoreconstructions of the marine silicon cycle. de la Rocha, C. and M. Bickle (2005). Sensitivity of silicon isotopes to whole-ocean changes in the silica cycle. Marine Geology 217, 267-282.

  17. Compiled records of carbon isotopes in atmospheric CO2 for historical simulations in CMIP6

    Science.gov (United States)

    Graven, Heather; Allison, Colin E.; Etheridge, David M.; Hammer, Samuel; Keeling, Ralph F.; Levin, Ingeborg; Meijer, Harro A. J.; Rubino, Mauro; Tans, Pieter P.; Trudinger, Cathy M.; Vaughn, Bruce H.; White, James W. C.

    2017-12-01

    The isotopic composition of carbon (Δ14C and δ13C) in atmospheric CO2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14C and 13C in the ocean and terrestrial components of Earth system models (ESMs) present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs' component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of Δ14C and δ13C in atmospheric CO2 for the historical period 1850-2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6) for models simulating carbon isotopes in the ocean or terrestrial biosphere. The data may also be useful for other carbon cycle modelling activities.

  18. The isotopic record of Northern Hemisphere atmospheric carbon monoxide since 1950: implications for the CO budget

    Directory of Open Access Journals (Sweden)

    Z. Wang

    2012-05-01

    Full Text Available We present a 60-year record of the stable isotopes of atmospheric carbon monoxide (CO from firn air samples collected under the framework of the North Greenland Eemian Ice Drilling (NEEM project. CO concentration, δ13C, and δ18O of CO were measured by gas chromatography/isotope ratio mass spectrometry (gc-IRMS from trapped gases in the firn. We applied LGGE-GIPSA firn air models (Witrant et al., 2011 to correlate gas age with firn air depth and then reconstructed the trend of atmospheric CO and its stable isotopic composition at high northern latitudes since 1950. The most probable firn air model scenarios show that δ13C decreased slightly from −25.8‰ in 1950 to −26.4‰ in 2000, then decreased more significantly to −27.2‰ in 2008. δ18O decreased more regularly from 9.8‰ in 1950 to 7.1‰ in 2008. Those same scenarios show CO concentration increased gradually from 1950 and peaked in the late 1970s, followed by a gradual decrease to present day values (Petrenko et al., 2012. Results from an isotope mass balance model indicate that a slight increase, followed by a large reduction, in CO derived from fossil fuel combustion has occurred since 1950. The reduction of CO emission from fossil fuel combustion after the mid-1970s is the most plausible mechanism for the drop of CO concentration during this time. Fossil fuel CO emissions decreased as a result of the implementation of catalytic converters and the relative growth of diesel engines, in spite of the global vehicle fleet size having grown several fold over the same time period.

  19. Diet in pottery-making societies from Central Chile: The contribution of stable isotope analyses

    International Nuclear Information System (INIS)

    Falabella, Fernanda; Planella, M.Teresa; Aspillaga, Eugenio; Sanhueza, Lorena; Tykot, Robert H

    2007-01-01

    This is the first time that stable carbon, nitrogen and oxygen isotope analyses of human bones and teeth have been used to reconstruct subsistence and settlement patterns of prehispanic ceramic societies from Central Chile. Isotope analyses, unlike the evidence from botanical, faunal and artifactual remains from archaeological sites, and from dental and skeletal pathologies, gave information of which resources were really eaten by each individual during the last years of their life. The human data were evaluated against isotopic values of marine and terrestrial resources from central Chile. These results were interpreted taking into consideration different lines of paleodiet evidence. The main contributions are: empirical evidence of dietary differences according to cultural groups; low dependence on marine foods for most people living on the coast; indirect evidence of mobility strategies that show differences between Early and Late Intermediate societies; increased dependence on maize with time, especially among the Aconcagua people; gender differences in maize consumption for the same Aconcagua groups, men showing the greatest levels of maize intake. The results support some hypotheses, such as the difference in dietary patterns between contemporary Bato and Lolleo groups, contradict others, such as the supposed importance of marine diet for coastal inhabitants, and open new research questions for the future [es

  20. A contribution to the future prospect of uranium laser-isotope separation

    International Nuclear Information System (INIS)

    Becker, F.S.

    1981-01-01

    The two-frequency multiphoton-dissociation of UF 6 seems promising, using a high-power laser, which is tunable in the 16 μm spectral region due to the frequency shift of the 10 μm CO 2 -laser radiation, induced by the stimulated rotational Raman effect of para-hydrogen. In the present experiments the isotope selectivity of the multiphoton-dissociation process is studied in order to contribute to the solution of some questions, as for example the influence of high fluorine concentrations on the optical dissociation of UF 6 . (DG) [de

  1. Lithospheric Contributions to Arc Magmatism: Isotope Variations Along Strike in Volcanoes of Honshu, Japan

    Science.gov (United States)

    Kersting; Arculus; Gust

    1996-06-07

    Major chemical exchange between the crust and mantle occurs in subduction zone environments, profoundly affecting the chemical evolution of Earth. The relative contributions of the subducting slab, mantle wedge, and arc lithosphere to the generation of island arc magmas, and ultimately new continental crust, are controversial. Isotopic data for lavas from a transect of volcanoes in a single arc segment of northern Honshu, Japan, have distinct variations coincident with changes in crustal lithology. These data imply that the relatively thin crustal lithosphere is an active geochemical filter for all traversing magmas and is responsible for significant modification of primary mantle melts.

  2. Temporal diet changes recorded by stable isotopes in Asiatic black bear (Ursus thibetanus) hair.

    Science.gov (United States)

    Mizukami, R N; Goto, M; Izumiyama, S; Yoh, M; Ogura, N; Hayashi, H

    2005-03-01

    Carbon and nitrogen stable isotope ratios were measured in hair samples of the Asiatic black bear (Ursus thibetanus) inhabiting the Northern Japanese Alps (NJA) (n = 20) and the periphery of Nagano City (NC) (n = 6), in Nagano Prefecture, Japan. The hair of NJA bears, which did not have access to anthropogenic foods, showed lower values of d13C and d15N than that of NC bears which had access to garbage and corn fields, especially during the summer. These results reflect somewhat differing diets between the NJA and NC bears. We attempted to assess the feeding history during the hair growth cycle using the growth section analysis method. Each hair sample had been cut into 3?mm lengths from root to tip, labeled, and analyzed along the hair growth. We measured the carbon and nitrogen stable isotope ratios of each 3?mm length of hair sample from one NC bear which had been killed while raiding a corn field. The sections showed wide ranges of isotope ratios, from -23.2% to -14.6% for delta13C, and from 0.3% to 4.6% for delta15N. It was shown that the diet of this bear shifted dramatically from principally C3 plants to more C4 plants and to foods of animal origin. An analysis of the whole hair reflects just the average feeding habit during hair growth, but the present method can trace its diet history. This method can contribute to obtain precise ecological information of wildlife.

  3. Trace gases and CO sub(2) isotope records from Cabo de Rama, India

    Digital Repository Service at National Institute of Oceanography (India)

    Bhattacharya, S.K.; Borole, D.V.; Francey, R.J.; Allison, C.E.; Steele, L.P.; Krummel, P.; Langenfelds, R.; Masarie, K.A.; Tiwari, Y.K.; Patra, P.K.

    to avoid dan- gerous climate change due to GHG forced warming. Con- centrations of CO 2 , CH 4 and N 2 O have increased at alarming rates, from preindustrial values of 280 ppm, 715 ppb and 270 ppb (circa. 1750) to 379 ppm, 1732 ppb and 319 ppb... an important effect on the con- centration and isotopic composition of atmospheric CO 2 , and the concentrations of other trace gases. Air sampling at CRI contributes to the global atmospheric composition study 10,11 . Given the potential for global impacts...

  4. Holocene elemental, lead isotope and charcoal record from peat in southern Poland

    Directory of Open Access Journals (Sweden)

    K. Tudyka

    2017-03-01

    Full Text Available This article presents a mid-resolution elemental, isotopic and charcoal record from 10700 BC to AD 500 in a peat core located in Żyglin (southern Poland. The objective is to give insight into the proxies with emphasis on lead (Pb sources in this minerogenic peat deposit. During the Early Holocene (10700–7550 BC the average 206Pb/207Pb quotient was around 1.196. This isotopic signature is consistent with natural dust derived from long-distance soil and rock weathering. The Mid-Holocene period (7550–3200 BC shows a significant change in the peat accumulation conditions. The growth rate is approximately 0.04 mm yr-1 and the 206Pb/207Pb quotients are shifted toward values that are found in local galena ores. This is simultaneous with a significantly increased lead flux which further confirms local sources of material in this peat deposit. In the Late Holocene period (3200 BC–AD 500 a large quantity of charcoal particles with diameters ranging from 2 mm up to 3 cm is found; also, Pb, Zn and Cu fluxes reach their highest values. This period corresponds to the Eneolithic, Bronze and Iron Ages, and human impact is recorded as charcoal.

  5. Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz.

    Science.gov (United States)

    Budd, David A; Troll, Valentin R; Deegan, Frances M; Jolis, Ester M; Smith, Victoria C; Whitehouse, Martin J; Harris, Chris; Freda, Carmela; Hilton, David R; Halldórsson, Sæmundur A; Bindeman, Ilya N

    2017-01-25

    Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ 18 O values. Overall, Toba quartz crystals exhibit comparatively high δ 18 O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ 18 O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆ core-rim  = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ 18 O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ 18 O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

  6. An oxygen isotope record from Lake Xiarinur in Inner Mongolia since the last deglaciation and its implication for tropical monsoon change

    Science.gov (United States)

    Sun, Qing; Chu, Guoqiang; Xie, Manman; Zhu, Qingzeng; Su, Youliang; Wang, Xisheng

    2018-04-01

    We present a high-resolution oxygen isotope record from authigenic carbonate (δ18Ocarb) from Lake Xiarinur (Inner Mongolia) since the last deglaciation. The lake is located at the modern northern limit of the monsoon, and is therefore sensitive to the extension of the East Asian summer monsoon. Based on calibration against the instrumental record, the δ18Ocar variation has been interpreted as changes in atmospheric circulation pattern on decadal time scales. On longer time scales, the δ18Ocarb in lake sediments could be mainly regulated by the relative contribution of nearby (remote) water-vapor sources associated with subtropical (tropical) monsoon through changes in the distance from sources to the site of precipitation. Increased remote water vapors from tropical monsoon would lead to lighter isotope value in our study site. Through time the δ18Ocarb record in Lake Xiarinur indicate a notable weak tropical monsoon during the Younger Dryas, a gradual increasing monsoon from the early Holocene and weakening monsoon after the middle Holocene. Oxygen isotope records from lakes and stalagmite in the Asian monsoon region across different localities show a general similar temporal pattern since the last deglaciation, and highlight a fundamental role of the tropical monsoon.

  7. Oxygen-isotope wiggle maching as a tol for synchronising ice-cor and terrestrial records over Termination !

    NARCIS (Netherlands)

    Hoek, W.Z.; Bohncke, S.J.P.

    2001-01-01

    In NW Europe, the large number of terrestrial records that are now available from Termination 1 (15-10kcal yr BP) form the basis for a highly detailed picture of Lateglacial environmental change. Nevertheless, the Greenland oxygen-isotope records (GRIP/GISP2) are still regarded as the best

  8. What climate information is recorded in stable isotope ratios of wood lignin methoxyl groups?

    Science.gov (United States)

    Greule, Markus; Keppler, Frank

    2010-05-01

    The stable isotope composition of the bioelements C, O, H and N in plant organic matter is known to be a very powerful for various environmental impacts. Particularly tree rings are suitable for this analysis because they exhibit a "climate archive" with a yearly or even biannual resolution. One of the most determined wood compounds is cellulose which amongst others is used to reconstruct the temperature due to measurement of stable hydrogen and oxygen isotopes. Therefore cellulose is converted into cellulose nitrate to eliminate the exchangeable hydroxyl hydrogen or equilibration methods are used. However, a general problem associated with the determination of the stable hydrogen values of marker compounds for the study of climate and environmental conditions is the isolation of the pure compound for analysis by isotope ratio mass spectrometry. Exploitation of components of wood as markers, in particular, has been restricted by the very labour intensive and time consuming preparation of samples (e.g. cellulose nitrate). An alternative way to record climate information from tree rings was recently proposed by Keppler et al. (2007) who measured the stable hydrogen values of methoxyl groups in wood. Lignin methoxyl groups are considered to be stable, i.e. the hydrogen atoms of the methoxyl moiety do not exchange with those of plant water during ongoing metabolic reactions in the plant. Thus the initial deuterium content of the methoxyl groups of lignin in woody tissue at formation is retained throughout the lifetime of the tree and in preserved tissue. The methoxyl content of lignin in wood is usually determined by the Zeisel method (Zeisel, 1885) - the reaction between methyl ethers and hydroiodic acid to form methyl iodide. Exploiting this reaction for the measurement of stable hydrogen values of lignin methoxyl groups ensures that during the entire analytical procedure the isotope signal is preserved since no isotopic exchange occurs between the methyl groups and

  9. Multiple Nebular Gas Reservoirs Recorded by Oxygen Isotope Variation in a Spinel-rich CAI in CO3 MIL 090019

    Science.gov (United States)

    Simon, J. I.; Simon, S. B.; Nguyen, A. N.; Ross, D. K.; Messenger, S.

    2017-01-01

    We conducted NanoSIMS O-isotopic imaging of a primitive spinel-rich CAI spherule (27-2) from the MIL 090019 CO3 chondrite. Inclusions such as 27-2 are proposed to record inner nebula processes during an epoch of rapid solar nebula evolution. Mineralogical and textural analyses suggest that this CAI formed by high temperature reactions, partial melting, and condensation. This CAI exhibits radial O-isotopic heterogeneity among multiple occurrences of the same mineral, reflecting interactions with distinct nebular O-isotopic reservoirs.

  10. Use of a Bayesian isotope mixing model to estimate proportional contributions of multiple nitrate sources in surface water

    International Nuclear Information System (INIS)

    Xue Dongmei; De Baets, Bernard; Van Cleemput, Oswald; Hennessy, Carmel; Berglund, Michael; Boeckx, Pascal

    2012-01-01

    To identify different NO 3 − sources in surface water and to estimate their proportional contribution to the nitrate mixture in surface water, a dual isotope and a Bayesian isotope mixing model have been applied for six different surface waters affected by agriculture, greenhouses in an agricultural area, and households. Annual mean δ 15 N–NO 3 − were between 8.0 and 19.4‰, while annual mean δ 18 O–NO 3 − were given by 4.5–30.7‰. SIAR was used to estimate the proportional contribution of five potential NO 3 − sources (NO 3 − in precipitation, NO 3 − fertilizer, NH 4 + in fertilizer and rain, soil N, and manure and sewage). SIAR showed that “manure and sewage” contributed highest, “soil N”, “NO 3 − fertilizer” and “NH 4 + in fertilizer and rain” contributed middle, and “NO 3 − in precipitation” contributed least. The SIAR output can be considered as a “fingerprint” for the NO 3 − source contributions. However, the wide range of isotope values observed in surface water and of the NO 3 − sources limit its applicability. - Highlights: ► The dual isotope approach (δ 15 N- and δ 18 O–NO 3 − ) identify dominant nitrate sources in 6 surface waters. ► The SIAR model estimate proportional contributions for 5 nitrate sources. ► SIAR is a reliable approach to assess temporal and spatial variations of different NO 3 − sources. ► The wide range of isotope values observed in surface water and of the nitrate sources limit its applicability. - This paper successfully applied a dual isotope approach and Bayesian isotopic mixing model to identify and quantify 5 potential nitrate sources in surface water.

  11. Triple nitrate isotopes indicate differing nitrate source contributions to streams across a nitrogen saturation gradient

    Science.gov (United States)

    Lucy A. Rose; Emily M. Elliott; Mary Beth. Adams

    2015-01-01

    Nitrogen (N) deposition affects forest biogeochemical cycles worldwide, often contributing to N saturation. Using long-term (>30-year) records of stream nitrate (NO3-) concentrations at Fernow Experimental Forest (West Virginia, USA), we classified four watersheds into N saturation stages ranging from Stage 0 (N-...

  12. The geochemical record of the ancient nitrogen cycle, nitrogen isotopes, and metal cofactors.

    Science.gov (United States)

    Godfrey, Linda V; Glass, Jennifer B

    2011-01-01

    The nitrogen (N) cycle is the only global biogeochemical cycle that is driven by biological functions involving the interaction of many microorganisms. The N cycle has evolved over geological time and its interaction with the oxygen cycle has had profound effects on the evolution and timing of Earth's atmosphere oxygenation (Falkowski and Godfrey, 2008). Almost every enzyme that microorganisms use to manipulate N contains redox-sensitive metals. Bioavailability of these metals has changed through time as a function of varying redox conditions, and likely influenced the biological underpinnings of the N cycle. It is possible to construct a record through geological time using N isotopes and metal concentrations in sediments to determine when the different stages of the N cycle evolved and the role metal availability played in the development of key enzymes. The same techniques are applicable to understanding the operation and changes in the N cycle through geological time. However, N and many of the redox-sensitive metals in some of their oxidation states are mobile and the isotopic composition or distribution can be altered by subsequent processes leading to erroneous conclusions. This chapter reviews the enzymology and metal cofactors of the N cycle and describes proper utilization of methods used to reconstruct evolution of the N cycle through time. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Carbon 13 and oxygen 18 isotope record of the early eocene nammal formation, salt range, pakistan

    International Nuclear Information System (INIS)

    Ghazi, S.; Sajid, Z.

    2014-01-01

    The Nammal Formation is the lowermost unit of the Early Eocene succession in the Salt Range, Pakistan. It is well exposed throughout the Salt Range. The Nammal Formation having 30 to 35 meters thickness is predominantly composed of nodular limestone interbedded with marl and shale. The present study was focussed on stable carbon 13 and oxygen 18 isotopic analysis based on data from two stratigraphically important sections. The samples from the Nilawahan section provided with the delta 13C values varied between 1.34 to -1.56 (VPDB) and values of delta 18O fluctuated between -4.47 to -6.59 (VPDB). Likewise the sample analysis of BadshahPur section exhibited that the delta 13C values changes from 1.09 to -1.65 (VPDB) and delta 18O values range from -4.17 to -6.85 (VPDB). The isotopic records of carbon 13 and oxygen 18 indicated the shallow marine deposition of the Nammal Formation under tropical conditions. It highlighted the palaeo climatic and diagenetic conditions of the Nammal Formation at the time of deposition in the Salt Range region. (author)

  14. Carbon and nitrogen isotopic signatures of bat guanos as record of past environments

    International Nuclear Information System (INIS)

    Mizutani, Hiroshi; Kabaya, Yuko; McFarlane, D.A.

    1992-01-01

    Carbon and nitrogen isotope ratios were measured for various ecogeochemical samples relevant to bat guano ecosystems. In particular, ca. 800-year-old subfossil guano from Jackson's Bay Cave Compex, Jamaica, yielded ratios similar to the modern guano from other Jamaican bat caves but quite different from modern guano of the same area. Diagenetic change and differences in bat food habits were unlikely explanations for the observation. Instead, insects that feed on C 4 and CAM plants were the main prey for the bats in present Jackson's Bay area, while the ultimate source of organic matter for bats in other Jamaican caves and for the bats that deposited guano in Jackson's Bay Great Cave ca. 800 years ago were C 3 photosynthesis. We suggests that the isotopic data indicate that the surrounding environment experienced a significant mesic episode in the recent past. This mesic climate would have supported a large population of bats, which in turn would have accumulated significant quantities of guano. The subsequent return to the more xeric conditions prevailing today would have caused a drastic reduction in bat population size and effectively ended significant guano accumulation. Fossil guano from Carlsbad Caverns, New Mexico, U.S.A., suggested that native C 3 plants might have been more abundant in Wisconsinan than today. Isotope analyses of old guanos from Bat Cave in Grand Canyon National Park, Arizona, U.S.A., found a possible implication that C 4 photosynthesis might have had contributed a little more to the bats' diet in the cave before the construction of Glen Canyon Dam. (author)

  15. Hydrogen isotopic messages in sulfate reducer lipids: a recorder of metabolic state?

    Science.gov (United States)

    Bradley, A. S.; Leavitt, W.; Zhou, A.; Cobban, A.; Suess, M.

    2017-12-01

    A significant range in microbial lipid 2H/1H ratios is observed in modern marine sediments. The magnitude of hydrogen isotope fractionation between microbial lipids and growth water (2ɛlipid-H2O) is hypothesized to relate to the central carbon and energy metabolism. These observations raise the possibility for culture independent identification of the dominant metabolic pathways operating in a given environment [Zhang et al. 2009]. One such metabolism we aim to track is microbial sulfate reduction. To-date, sulfate reducing bacteria have been observed to produce lipids that are depleted in fatty acid H-isotope composition, relative to growth water (2ɛlipid-H2O -50 to -175 ‰) [Campbell et al. 2009; Dawson et al. 2015; Osburn et al.], with recent work demonstrating a systematic relationship between lipid/water fractionation and growth rate when the electron-bifurcating NAD(P)(H) transhydrogenase (ebTH) activity was disrupted and the available electron requires the ebTH [Leavitt et al. 2016. Front Microbio]. Recent work in aerobic methylotrophs [Bradley et al. 2014. AGU] implicates non-bifurcating NAD(P)(H) transhydrogenase activity is a critical control on 2ɛlipid-H2O. This suggests a specific mechanism to control the range in fractionation is the ratio of intracellular NADPH/NADH/NADP/NAD in aerobes and perhaps the same in anaerobes with some consideration for FADH/FAD. Fundamentally this implies 2ɛlipid-H2O records intracellular redox state. In our sulfate reducer model system Desulfovibrio alaskensis strain G20 a key component of energy metabolism is the activity of ebTH. Nonetheless, this strain contains two independent copies of the genes, only one of which generates a distinctive isotopic phenotype [Leavitt et al. 2016. Front Microbio]. In this study we extend the recent work in G20 to continuous culture experiments comparing WT to nfnAB-2 transposon interruptions, where both organisms are cultivated continuously, at the rate of the slower growing mutant

  16. Sulfur isotope variability of oceanic DMSP generation and its contributions to marine biogenic sulfur emissions.

    Science.gov (United States)

    Oduro, Harry; Van Alstyne, Kathryn L; Farquhar, James

    2012-06-05

    Oceanic dimethylsulfoniopropionate (DMSP) is the precursor to dimethylsulfide (DMS), which plays a role in climate regulation through transformation to methanesulfonic acid (MSA) and non-seasalt sulfate (NSS-SO(4)(2-)) aerosols. Here, we report measurements of the abundance and sulfur isotope compositions of DMSP from one phytoplankton species (Prorocentrum minimum) and five intertidal macroalgal species (Ulva lactuca, Ulva linza, Ulvaria obscura, Ulva prolifera, and Polysiphonia hendryi) in marine waters. We show that the sulfur isotope compositions (δ(34)S) of DMSP are depleted in (34)S relative to the source seawater sulfate by ∼1-3‰ and are correlated with the observed intracellular content of methionine, suggesting a link to metabolic pathways of methionine production. We suggest that this variability of δ(34)S is transferred to atmospheric geochemical products of DMSP degradation (DMS, MSA, and NSS-SO(4)(2-)), carrying implications for the interpretation of variability in δ(34)S of MSA and NSS-SO(4)(2-) that links them to changes in growth conditions and populations of DMSP producers rather than to the contributions of DMS and non-DMS sources.

  17. Sources and Contributions of Oxygen During Microbial Pyrite Oxidation: the Triple Oxygen Isotopes of Sulfate

    Science.gov (United States)

    Ziegler, K.; Coleman, M. L.; Mielke, R. E.; Young, E. D.

    2008-12-01

    The triple isotopes of oxygen (Δ17O' = δ17O'-0.528 × δ18O' using logarithmic deltas) can trace the oxygen sources of sulfate produced during sulfide oxidation, an important biogeochemical process on Earth's surface and possibly also on Mars [1]. δ18OSO4 compositions are determined by the isotopic selectivity of the mechanism(s) responsible for their changes, and the δ18O value of the reactants (O2 vs. H2O). The relative proportional importance and contribution of each of those sources and mechanisms, as well as their associated isotopic fractionations, are not well understood. We are investigating the use of Δ 17O as a quantitative and qualitative tracer for the different processes and oxygen sources involved in sulfate production. Δ17O signatures are distinct fingerprints of these reservoirs, independent of fractionation factors that can be ambiguous. We conducted controlled abiotic and biotic (Acidithiobacillus ferrooxidans, A.f.) laboratory experiments in which water was spiked with 18O, allowing us to quantify the sources of sulfate oxygen and therefore the processes attending sulfate formation. Results of this Δ17O tracer study show that A.f. microbes initiate pyrite S-oxidation within hours of exposure, and that sulfate is produced from ~90% atmospheric oxygen. This initial lag-phase (behavior in the initial lag-phase will aid in the understanding of the ecological conditions required for microbial populations to establish and survive. An exponential phase of growth, facilitated by microbial Fe2+-oxidation, follows. The source of sulfate rapidly switches to abiotic sulfide oxidation during exponential growth and the source of oxygen switches from atmospheric O2 to nearly ~100% water. Pending acquisition of complimentary chemistry data (in progress), we interpret our isotope data to indicate that the biotic fractionation factor ɛ18OSO4-O2 of at least ~ -25 to - 35‰ is augmented by microbially induced kinetic fractionation; it is larger than

  18. Patterns of contribution to citizen science biodiversity projects increase understanding of volunteers' recording behaviour.

    Science.gov (United States)

    Boakes, Elizabeth H; Gliozzo, Gianfranco; Seymour, Valentine; Harvey, Martin; Smith, Chloë; Roy, David B; Haklay, Muki

    2016-09-13

    The often opportunistic nature of biological recording via citizen science leads to taxonomic, spatial and temporal biases which add uncertainty to biodiversity estimates. However, such biases may also give valuable insight into volunteers' recording behaviour. Using Greater London as a case-study we examined the composition of three citizen science datasets - from Greenspace Information for Greater London CIC, iSpot and iRecord - with respect to recorder contribution and spatial and taxonomic biases, i.e. when, where and what volunteers record. We found most volunteers contributed few records and were active for just one day. Each dataset had its own taxonomic and spatial signature suggesting that volunteers' personal recording preferences may attract them towards particular schemes. There were also patterns across datasets: species' abundance and ease of identification were positively associated with number of records, as was plant height. We found clear hotspots of recording activity, the 10 most popular sites containing open water. We note that biases are accrued as part of the recording process (e.g. species' detectability) as well as from volunteer preferences. An increased understanding of volunteer behaviour gained from analysing the composition of records could thus enhance the fit between volunteers' interests and the needs of scientific projects.

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

    Science.gov (United States)

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

    2013-12-01

    [1] Natural archives of oxygen isotopes in precipitation may be used to study changes in the hydrological cycle in the tropics, but their interpretation is not straightforward. We studied to which degree tree rings of Mimosa acantholoba from southern Mexico record variation in isotopic composition of precipitation and which climatic processes influence oxygen isotopes in tree rings ( δ 18 O tr ). Interannual variation in δ 18 O tr was highly synchronized between trees and closely related to isotopic composition of rain measured at San Salvador, 710 km to the southwest. Correlations with δ 13 C, growth, or local climate variables (temperature, cloud cover, vapor pressure deficit (VPD)) were relatively low, indicating weak plant physiological influences. Interannual variation in δ 18 O tr correlated negatively with local rainfall amount and intensity. Correlations with the amount of precipitation extended along a 1000 km long stretch of the Pacific Central American coast, probably as a result of organized storm systems uniformly affecting rainfall in the region and its isotope signal; episodic heavy precipitation events, of which some are related to cyclones, deposit strongly 18 O-depleted rain in the region and seem to have affected the δ 18 O tr signal. Large-scale controls on the isotope signature include variation in sea surface temperatures of tropical north Atlantic and Pacific Ocean. In conclusion, we show that δ 18 O tr of M . acantholoba can be used as a proxy for source water δ 18 O and that interannual variation in δ 18 O prec is caused by a regional amount effect. This contrasts with δ 18 O signatures at continental sites where cumulative rainout processes dominate and thus provide a proxy for precipitation integrated over a much larger scale. Our results confirm that processes influencing climate-isotope relations differ between sites located, e.g., in the western Amazon versus coastal Mexico, and that tree ring isotope records can help in

  20. Dual temperature effects on oxygen isotopic ratio of shallow-water coral skeleton: Consequences on seasonal and interannual records

    Science.gov (United States)

    Juillet-Leclerc, A.; Reynaud, S.

    2009-04-01

    Oxygen isotopic ratio from coral skeleton is regarded for a long time as promising climate archives at seasonal scale. Although in isotopic disequilibrium relative to seawater, it is supposed to obey to the isotope thermometer. Indeed, coral oxygen isotopic records are strongly temperature dependent, but d18O-temperature calibrations derived from different corals are highly variable. The isotope thermometer assumption does not take into account vital effects due to biogenic origin of the mineral. Corals are animals living in symbiosis with algae (zooxanthellae). Interactions between symbiont photosynthesis and coral skeleton carbonation have been abundantly observed but they remain poorly understood and the effects of photosynthesis on coral growth and skeleton oxygen ratio are ignored. Coral cultured under two light conditions enabled to relate metabolic parameters and oxygen isotopic variability with photosynthetic activity. By examining responses provided by each colony they revealed that photosynthesis significantly affected d18O, by an opposite sense compared with the sole temperature influence. Since temperature and light changes are associated during seasonal variations, this complicates the interpretation of seasonal record. Additionally, this complexity is amplified because photosynthetic activity is also directly impacted by temperature variability. Thus, the annual isotopic amplitude due to the "physical" temperature influence is partly compensated through photosynthesis. Similar opposite effect is also shown by extension rate of the cultured colonies. First, we will examine and quantify consequences of photosynthesis on growth rate and oxygen isotopic signature, from cultured corals. Second, we will consider the consequences of this vital effect on data series, at seasonal and interannual time scales.

  1. Geomorphic Drainage Capture Recorded by Oxygen Isotopes of Green River Formation Lacustrine Mudstone, Eocene, Wyoming

    Science.gov (United States)

    Doebbert, A. C.; Booth, A. L.; Carroll, A.; Chamberlain, C.; Rhodes, M.

    2005-12-01

    The isotopic composition of cement and other meteoric precipitates are increasingly being used to interpret orogenic uplift histories, based on the relationship between altitude and rainwater δ18O. However, other variables such as changing regional drainage patterns may also affect the downstream composition of surface waters, especially when multiple drainages commingle in a lake. The Green River Formation contains some of the best documented lacustrine deposits in the world, making it ideal for examining such issues. Carbonate mudstone in balanced-fill facies of the lower LaClede Bed averages 3.41‰ (PDB), and records a deep, saline to brackish lake that fluctuated near its sill. In contrast, overfilled facies of the upper LaClede Bed record a freshwater lake, and δ18O reaches values as low as -9.72‰. This transition occurred shortly after deposition of the Analcite Tuff at 48.94 ± 0.12 Ma (Smith et al., 2003), and was geologically abrupt. Based on 40Ar/39Ar-calibrated sediment accumulation rates it required no more than 200-300 ky. An almost identical transition occurs in two cores separated by about 30 km, making local diagenesis an unlikely cause. The magnitude of δ18O change is similar to that in some uplift studies, but its rapidity virtually excludes uplift as a controlling mechanism. Instead, we propose that both the change in sedimentation and the sharp decrease in δ18O are the result of a drainage capture event. The addition of a new drainage to the basin may have adjusted isotopic values in two ways: by introducing runoff with relatively low δ18O, and by decreasing residence time (and therefore evaporation) of lake water. Decreasing 87Sr/86Sr across the same transition suggests that the newly added waters may have been sourced from rising volcanic topography to the north in the Absaroka province. Although this rising topography allows for the possibility of some uplift component, the rate of change in lacustrine δ18O is consistent with

  2. Spanish Network for Isotopes in Precipitation: Isotope Spatial distribution and contribution to the knowledge of the hydrological cycle

    International Nuclear Information System (INIS)

    Diaz-Teijeiro, M. F.; Rodriguez-Arevalo, J.; Castano, S.

    2009-01-01

    The results of seven years of operation of the Spanish Network for Isotopes ( 2 H, 1 8O y 3 H) in Precipitation (REVIP) are shown. this Network is managed since 2000 by the Centro de Estudios de Tecnicas Aplicadas of the Centro de Estudios y Experimentacion de Obras Publicas (CEDEX) in collaboration with the Agencia Estatal de Meteorologia (AEMET). The results of REVIP are sent to the International Atomic Energy Agency (IAEA) in order to be integrated in the Global Network for Isotopes in Precipitation (GNIP). The spatial distribution of stable isotopes ( 1 8O h 2 H) in precipitation in Spain follows a multiple regression model, based on two geographic factors: latitude and elevation, which is strongly correlated with temperature, an important factor controlling isotope fractionation. This information on 1 8O and 2 H is useful to trace surface and ground waters and, combined with the information, about the spatial and temporal distribution of the Tritium ( 3 H) concentration in precipitation, allows to date these waters in order to estimate flow directions and velocities, and to evaluate the residence time of water resources and aquifer vulnerability. (Author)

  3. Climatic signals in multiple highly resolved stable isotope records from Greenland

    DEFF Research Database (Denmark)

    Vinther, Bo Møllesøe; Dahl-Jensen, Dorthe; Johnsen, Sigfus Johann

    2010-01-01

    are found to correspond better with winter stable isotope data than with summer or annual average stable isotope data it is suggested that a strong local Greenland temperature signal can be extracted from the winter stable isotope data even on centennial to millennial time scales. Udgivelsesdato: Feb....

  4. Limnological controls on stable isotope records of late-holocene palaeoenvironment change in sw greenland: A paired lake study

    DEFF Research Database (Denmark)

    Olsen, Jesper; John Anderson, N.; Leng, M.J.

    2013-01-01

    Stable isotope records are increasingly being used in palaeoenvironmental studies of Arctic lakes. Here we compare stable isotope and elemental records (δ13C, δ15N, C/N) with high resolution XRF-derived geochemical and colour data from low Arctic lakes (SS1220 and SS85) in southwest Greenland. Lake...... SS1220 sediments are laminated gyttja whereas SS85 consist of homogeneous gyttja, both records cover the last c. 5000 years. d13C and carbon content suggest that organic matter in both lakes is predominantly autochthonous. The C/N variability, ranging between 11 and 15, is interpreted...... composition of lake sediments when there is a reasonable understanding of limnological processes, and records may be lake specific....

  5. Isotopic chemical weathering behaviour of Pb derived from a high-Alpine Holocene lake-sediment record

    Science.gov (United States)

    Gutjahr, Marcus; Süfke, Finn; Gilli, Adrian; Anselmetti, Flavio; Glur, Lukas; Eisenhauer, Anton

    2017-04-01

    Several studies assessing the chemical weathering systematics of Pb isotopes provided evidence for the incongruent release of Pb from source rocks during early stages of chemical weathering, resulting in runoff compositions more radiogenic (higher) than the bulk source-rock composition [e.g. 1]. Deep NW Atlantic seawater Pb isotope records covering the last glacial-interglacial transition further support these findings. Clear excursions towards highly radiogenic Pb isotopic input in the deep NW Atlantic seen during the early Holocene, hence after the large-scale retreat of the Laurentide Ice Sheet in North America, are interpreted to be controlled by preferential release of radiogenic Pb from U- and Th-rich mineral phases during early stages of chemical weathering that are less resistant to chemical dissolution than other rock-forming mineral phases [2-4]. To date, however, no terrestrial Pb isotope record exists that could corroborate the evidence from deep marine sites for efficient late deglacial weathering and washout of radiogenic Pb. We present a high-resolution adsorbed Pb isotope record from a sediment core retrieved from Alpine Lake Grimsel (1908 m.a.s.l.) in Switzerland, consisting of 117 Pb compositions over the past 10 kyr. This high-Alpine study area is ideally located for incipient and prolonged chemical weathering studies. The method used to extract the adsorbed lake Pb isotope signal is identical to previous marine approaches targeting the authigenic Fe-Mn oxyhydroxides fraction within the lake sediments [5, 6]. The Pb isotope compositions are further accompanied by various elemental ratios derived from the same samples that equally trace climatic boundary conditions in the Grimsel Lake area. The Pb isotopic composition recorded in Lake Grimsel is remarkably constant throughout the majority of the Holocene until ˜2.5 ka BP, despite variable sediment composition and -age, and isotopically relatively close to the signature of the granitic source rock

  6. Ca and Sr isotope records support ocean acidification during end-Permian mass extinction

    Science.gov (United States)

    Wang, J.; Jacobson, A. D.; Zhang, H.; Ramezani, J.; Sageman, B. B.; Hurtgen, M.; Bowring, S. A.; Shen, S.

    2017-12-01

    The end-Permian mass extinction represents the most devastating loss of biodiversity during the Phanerozoic. A negative carbon isotope (δ13C) excursion that accompanies the event suggests a significant perturbation to the global carbon cycle, likely induced by CO2 emissions during eruption of the Siberian Traps large igneous province. The carbon cycle is linked with the Ca and Sr cycles through chemical weathering and carbonate precipitation. Therefore, analyses of Ca (δ44/40Ca), radiogenic Sr (87Sr/86Sr), and stable Sr (δ88/86Sr) isotope abundance variations in marine carbonate rocks spanning the Permian-Triassic Boundary (PTB) can reveal key information about biogeochemical changes that occurred during this time. We report δ44/40Ca, 87Sr/86Sr, and δ88/86Sr records analyzed by TIMS for the Meishan and Dajiang sections in China. δ44/40Ca values exhibit similar patterns in both sections. The values remain unchanged across the extinction event layer (EXT) and then decrease by 0.20‰ before increasing by 0.20‰ to 0.40‰ around the PTB. In the Meishan section, 87Sr/86Sr ratios increase after the EXT and return to pre-excursion levels by the PTB. Simultaneously, δ88/86Sr values decrease by 0.12‰ across the EXT and increase by 0.08‰ by the PTB. The patterns of our data support the hypothesis that elevated atmospheric CO2 levels enhanced chemical weathering inputs and might have caused transient ocean acidification, with an "alkalinity overshoot" and increased carbonate deposition occurring after the extinction. Additional measurements and model calculations are underway to help refine and improve these preliminary interpretations.

  7. Direct dating of the oxygen-isotope record of the last deglaciation by 14C accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Duplessy, J.C.; Arnold, Maurice; Maurice, Pierre; Bard, Edouard; Duprat, Josette; Moyes, Jean

    1986-01-01

    The authors have measured 14 C for various species of foraminifera to produce a reliable timescale for the oxygen-isotope record. The results show that, at the end of the last ice age, continental ice sheets began to melt more than 4,000 yr before the Northern Hemisphere maximum of summer calorific radiation. (author)

  8. Contrasting Cu-Au and Sn-W Granite Metallogeny through the Zircon Geochemical and Isotopic Record

    Science.gov (United States)

    Gardiner, Nicholas; Hawkesworth, Chris; Robb, Laurence; Whitehouse, Martin; Roberts, Nick; Kirkland, Chris

    2017-04-01

    Magmatic genesis and evolution - mediated by geodynamic setting - exert a primary control on the propensity of granites to be metal fertile. A revolution in our understanding of these petrogenetic processes has been made through a range of mineral-based tools, most notably the common accessory mineral zircon. There is consequently considerable interest in whether the geochemical and isotopic compositions of zircon can be applied to metallogenic problems. The paired magmatic belts of Myanmar have broadly contrasting metallogenic affinities (Sn-W versus Cu-Au), and are interpreted to have formed on the accretionary margin of the subducting Neo-Tethys Ocean. They therefore present the opportunity to geochemically compare and contrast the zircon compositions in two end-member types of granite-hosted mineral deposits generated in collisional settings. We present an integrated zircon isotope (U-Pb, Lu-Hf, O) and trace element dataset that fingerprint: (a) source; (b) redox conditions; and (c) degree of fractionation. These variables all impact on magma fertility, and our key question to address is whether they can be reliably traced and calibrated within the Myanmar zircon record. Granitoid-hosted zircons from the I-type copper arc have juvenile ɛHf (+7 to +12) and mantle-like δ18O (5.3 ‰), whereas zircons from the S-type tin belt have low ɛHf (-7 to -13) and heavier δ18O (6.2-7.7 ‰). Plotting Hf versus U/Yb reaffirms that the tin belt magmas contain greater crustal contributions than the copper arc rocks. Links between whole rock Rb/Sr and zircon Eu/Eu* highlights that the latter can be used to monitor magma fractionation in systems that crystallize plagioclase (low Sr/Y). Ce/Ce* and Eu/Eu* in zircon are thus sensitive to redox and fractionation respectively, and can be used to evaluate the sensitivity of zircons to the metallogenic affinity of their host rocks. Tin contents that exceed the solubility limit are required in order to make a magmatic

  9. Glacial/interglacial wetland, biomass burning, and geologic methane emissions constrained by dual stable isotopic CH4 ice core records

    Science.gov (United States)

    Bock, Michael; Schmitt, Jochen; Beck, Jonas; Seth, Barbara; Chappellaz, Jérôme; Fischer, Hubertus

    2017-07-01

    Atmospheric methane (CH4) records reconstructed from polar ice cores represent an integrated view on processes predominantly taking place in the terrestrial biogeosphere. Here, we present dual stable isotopic methane records [δ13CH4 and δD(CH4)] from four Antarctic ice cores, which provide improved constraints on past changes in natural methane sources. Our isotope data show that tropical wetlands and seasonally inundated floodplains are most likely the controlling sources of atmospheric methane variations for the current and two older interglacials and their preceding glacial maxima. The changes in these sources are steered by variations in temperature, precipitation, and the water table as modulated by insolation, (local) sea level, and monsoon intensity. Based on our δD(CH4) constraint, it seems that geologic emissions of methane may play a steady but only minor role in atmospheric CH4 changes and that the glacial budget is not dominated by these sources. Superimposed on the glacial/interglacial variations is a marked difference in both isotope records, with systematically higher values during the last 25,000 y compared with older time periods. This shift cannot be explained by climatic changes. Rather, our isotopic methane budget points to a marked increase in fire activity, possibly caused by biome changes and accumulation of fuel related to the late Pleistocene megafauna extinction, which took place in the course of the last glacial.

  10. Subduction Contributions in the Trans-Mexican Volcanic Belt: Implications from Lava Chemistry and Hf-Nd-Pb Isotopes

    Science.gov (United States)

    Cai, Y.; Goldstein, S. L.; Langmuir, C. H.; Gómez-Tuena, A.; Lagatta, A.; Straub, S. M.; Martín Del Pozzo, A.

    2007-05-01

    Despite thick continental crust, near primitive lavas erupt throughout the Trans-Mexican Volcanic Belt (TMVB). In order to distinguish and better constrain subduction contributions and effects of crustal contamination, we analyzed samples representing subducting sediments from DSDP Site 487, and Quaternary lavas from stratovolcanoes and cinder cones, including alkaline "high-Nb" lavas from the Sierra Chichinautzin Volcanic Field (SCVF) showing negligible subduction signature in its trace element chemistry and representing melts of the mantle wedge. Our primary observations and implications are: (1) The high-Nb SCVF `intraplate' lavas define a linear trend along the "Nd-Hf mantle-crust array", defining the composition of the mantle wedge. (2) Popocatepetl and Nevado de Toluca stratovolcanoes show the highest Nd and Hf isotope ratios, higher than the `intraplate' lavas, indicating their sources are more "depleted mantle-like" than the regional mantle wedge. (3) The Popo and Toluca chemical and isotopic trends sharply contrast with Pico de Orizaba, which shows classic indications of crustal contamination (e.g. high 207Pb/204Pb, low Nd-Hf isotope ratios), consistent with contamination by local Precambrian crust. (4) Higher Nd-Hf isotopes in Popo and Toluca lavas also correlate with lower Pb isotope ratios, and lower Lu/Hf and Zr/Hf. Together, these data indicate contributions from subducted Pacific oceanic crust and hydrothermal sediment. (5) Popo and Toluca are also enriched in Th/LREE compared with `intraplate' lavas, reflecting subducted sediment contributions. (6) Nd-Hf isotope ratios of hydrothermal sediment from DSDP Site 487 lie on the "seawater array", with high Hf isotope ratios compared to the "mantle-crust array". Popo and Toluca Nd-Hf isotopes display a shallower slope than the "intraplate lava Nd-Hf array", reflecting contributions from hydrothermal sediment. Popocatepetl and Toluca lavas therefore avoid substantial crustal contamination of mantle wedge

  11. Biomarker and stable carbon isotopic signatures for 100–200 year sediment record in the Chaihe catchment in southwest China

    International Nuclear Information System (INIS)

    Wang, Yanhua; Yang, Hao; Zhang, Jixiang; Xu, Meina; Wu, Changbin

    2015-01-01

    Natural inputs and anthropogenic influences on lakes and their catchments are reflected in the sediment record. In the present study, the extractable organic compounds from sediments in the Chaihe catchment of the Dianchi watershed were analyzed to characterize source inputs. Results show that the sediments are dominated by odd numbered n-alkanes (n-C 16 –n-C 33 ), maximizing at n-C 17 , n-C 29 and n-C 31 . Aliphatic hydrocarbon may be composed of terrestrial plants and bacteria. The values of δ 13 C 27 , δ 13 C 29 and δ 13 C 31 of n-alkanes exhibit a range from − 33.27‰ to − 25.46‰, from − 35.76‰ to − 28.47‰ and from − 33.67‰ to − 27.42‰, respectively and three records strongly covary with depth, falling within the range of C 3 plants in the study area. An isotopic model revealed C 3 plant contribution to sedimentary organic matter (OM) ranging from 40.75% to 97.22%. The values of ACL 27–33 , CPI 27–33 , OEP, Paq, Pr/Ph, (C 27 + C 29 )/2C 31 , (C 21 + C 23 + C 25 )/3C 17 and nC 26 − /nC 27 + are consistent with the C 3 plant predominance. A constant CRS model gave the accumulation rates ranging from 2.69 to 8.46 mm a −1 spanning 1885–2010. It was concluded that OM transport in the Chaihe catchment was influenced strongly by human activities resulting in enhanced eutrophication. - Highlights: • Strong predominance of odd-numbered n-alkanes maximized at n-C 17 , n-C 29 and n-C 31 • Sedimentary OM in the Chaihe catchment was deduced mainly from C 3 plants. • Human activities enhanced OM transport, resulting in worse ecosystem

  12. Oxygen isotopes of marine mollusc shells record Eocene elevation change in the Pyrenees

    Science.gov (United States)

    Huyghe, Damien; Mouthereau, Frédéric; Emmanuel, Laurent

    2012-09-01

    Constraining paleoaltimetry of collisional orogens is critical to understand the dynamics of topographic evolution and climate/tectonics retroactions. Here, we use oxygen stable-isotope record on oyster shells, preserved in marine foreland deposits, to examine the past elevation of the Pyrenees during the Eocene. Our approach is based on the comparison with the Paris basin, an intracratonic basin not influenced by orogenic growth. The finding of a shift of 1.5‰ between 49 and 41 Ma, indicating more negative δ18Oc in the south Pyrenean foreland, is interpreted to reflect the inflow of river water sourced from higher elevation in the Pyrenees. To test this and provide paleoelevation estimate, we adopt a morphologic-hydrological model accounting for the hypsometry of drainage basin. Our best fitting model shows that the Pyrenees rose up to 2000 m. This indicates that the Pyrenees reached high elevation in the Eocene, thus providing new critical constraints on their long-term orogenic development. δ18O of marine mollusc shells are proved potentially attractive for paleoelevation studies, especially for mountain belts where elevated continental surfaces have not been preserved.

  13. Isotopic abundance of 13 C and contribution of eucalyptus biomass to soil organic matter conversion

    Directory of Open Access Journals (Sweden)

    Fabiane Figueiredo Severo

    Full Text Available ABSTRACT: It has become possible to evaluate the conversion of soil organic matter (SOM in pastures and arboreal crops due to the difference between the photosynthetic cycles of Eucalyptus (C3 and most grasses (C4. The auto analyzer method coupled to the IRMS (Isotope Ratio Mass Spectrometer in the present study evaluated the 13C content in soil profiles of Eucalyptus plantations of different ages (2, 10 and 21 years, in natural regeneration areas and natural grazing fields, and estimated the SOM conversion of each crop type of. The initial management of all sampled areas was natural pasture. The following profile layers were evaluated: 0-5, 5-10, 10-20, 20-30, 30-40, 40-50, 50-70 and 70-90cm, and the contribution of Eucalyptus biomass over the years of farming was estimated in the SOM conversion process. After 2 years of planting Eucalyptus, the beginning of pasture carbon conversion process occurred in the surface layer (0-5cm. Ten years after planting, the process of converting organic matter by arboreal crops reached the layers up to 20cm. After 21 years of planting and in natural regeneration areas, the entire profile has already been changed by planting Eucalyptus and native tree species.

  14. Sulfur Isotope Trends in Archean Microbialite Facies Record Early Oxygen Production and Consumption

    Science.gov (United States)

    Zerkle, A.; Meyer, N.; Izon, G.; Poulton, S.; Farquhar, J.; Claire, M.

    2014-12-01

    The major and minor sulfur isotope composition (δ34S and Δ33S) of pyrites preserved in ~2.65-2.5 billion-year-old (Ga) microbialites record localized oxygen production and consumption near the mat surface. These trends are preserved in two separate drill cores (GKF01 and BH1-Sacha) transecting the Campbellrand-Malmani carbonate platform (Ghaap Group, Transvaal Supergroup, South Africa; Zerkle et al., 2012; Izon et al., in review). Microbialite pyrites possess positive Δ33S values, plotting parallel to typical Archean trends (with a Δ33S/δ34S slope of ~0.9) but enriched in 34S by ~3 to 7‰. We propose that these 34S-enriched pyrites were formed from a residual pool of sulfide that was partially oxidized via molecular oxygen produced by surface mat-dwelling cyanobacteria. Sulfide, carrying the range of Archean Δ33S values, could have been produced deeper within the microbial mat by the reduction of sulfate and elemental sulfur, then fractionated upon reaction with O2 produced by oxygenic photosynthesis. Preservation of this positive 34S offset requires that: 1) sulfide was only partially (50­­-80%) consumed by oxidation, meaning H2S was locally more abundant (or more rapidly produced) than O2, and 2) the majority of the sulfate produced via oxidation was not immediately reduced to sulfide, implying either that the sulfate pool was much larger than the sulfide pool, or that the sulfate formed near the mat surface was transported and reduced in another part of the system. Contrastingly, older microbialite facies (> 2.7 Ga; Thomazo et al., 2013) appear to lack these observed 34S enrichments. Consequently, the onset of 34S enrichments could mark a shift in mat ecology, from communities dominated by anoxygenic photosynthesizers to cyanobacteria. Here, we test these hypotheses with new spatially resolved mm-scale trends in sulfur isotope measurements from pyritized stromatolites of the Vryburg Formation, sampled in the lower part of the BH1-Sacha core. Millimeter

  15. A Two-year Record of Daily Rainfall Isotopes from Fiji: Implications for Reconstructing Precipitation from Speleothem δ18O

    Science.gov (United States)

    Brett, M.; Mattey, D.; Stephens, M.

    2015-12-01

    Oxygen isotopes in speleothem provide opportunities to construct precisely dated records of palaeoclimate variability, underpinned by an understanding of both the regional climate and local controls on isotopes in rainfall and groundwater. For tropical islands, a potential means to reconstruct past rainfall variability is to exploit the generally high correlation between rainfall amount and δ18O: the 'amount effect'. The GNIP program provides δ18O data at monthly resolution for several tropical Pacific islands but there are few data for precipitation isotopes at daily resolution, for investigating the amount effect over different timescales in a tropical maritime setting. Timescales are important since meteoric water feeding a speleothem has undergone storage and mixing in the aquifer system and understanding how the isotope amount effect is preserved in aquifer recharge has fundamental implications on the interpretation of speleothem δ18O in terms of palaeo-precipitation. The islands of Fiji host speleothem caves. Seasonal precipitation is related to the movement of the South Pacific Convergence Zone, and interannual variations in rainfall are coupled to ENSO behaviour. Individual rainfall events are stratiform or convective, with proximal moisture sources. We have daily resolution isotope data for rainfall collected at the University of the South Pacific in Suva, covering every rain event in 2012 and 2013. δ18O varies between -18‰ and +3‰ with the annual weighted averages at -7.6‰ and -6.8‰ respectively, while total recorded rainfall amount is similar in both years. We shall present analysis of our data compared with GNIP, meteorological data and back trajectory analyses to demonstrate the nature of the relationship between rainfall amount and isotopic signatures over this short timescale. Comparison with GNIP data for 2012-13 will shed light on the origin of the amount effect at monthly and seasonal timescales in convective, maritime, tropical

  16. Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts

    International Nuclear Information System (INIS)

    Benech, H.

    1999-01-01

    The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, 25 Mg and 26 Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

  17. History of Animals using Isotope Records (HAIR): a 6-year dietary history of one family of African elephants.

    Science.gov (United States)

    Cerling, Thure E; Wittemyer, George; Ehleringer, James R; Remien, Christopher H; Douglas-Hamilton, Iain

    2009-05-19

    The dietary and movement history of individual animals can be studied using stable isotope records in animal tissues, providing insight into long-term ecological dynamics and a species niche. We provide a 6-year history of elephant diet by examining tail hair collected from 4 elephants in the same social family unit in northern Kenya. Sequential measurements of carbon, nitrogen, and hydrogen isotope rations in hair provide a weekly record of diet and water resources. Carbon isotope ratios were well correlated with satellite-based measurements of the normalized difference vegetation index (NDVI) of the region occupied by the elephants as recorded by the global positioning system (GPS) movement record; the absolute amount of C(4) grass consumption is well correlated with the maximum value of NDVI during individual wet seasons. Changes in hydrogen isotope ratios coincided very closely in time with seasonal fluctuations in rainfall and NDVI whereas diet shifts to relatively high proportions of grass lagged seasonal increases in NDVI by approximately 2 weeks. The peak probability of conception in the population occurred approximately 3 weeks after peak grazing. Spatial and temporal patterns of resource use show that the only period of pure browsing by the focal elephants was located in an over-grazed, communally managed region outside the protected area. The ability to extract time-specific longitudinal records on animal diets, and therefore the ecological history of an organism and its environment, provides an avenue for understanding the impact of climate dynamics and land-use change on animal foraging behavior and habitat relations.

  18. Chemical and oxygen isotope zonings in garnet from subducted continental crust record mineral replacement and metasomatism

    Science.gov (United States)

    Vho, Alice; Rubatto, Daniela; Regis, Daniele; Baumgartner, Lukas; Bouvier, Anne-Sophie

    2017-04-01

    , and variations up to 6.5‰ in Cima Bonze garnets suggest significant metasomatic replacement from external fluids. The combination of oxygen isotopes, trace element geochemistry and P-T modelling allows reconstructing the major stages of metasomatism, as well as identifying the nature of the fluid interacting with the rock at each metamorphic stage. REFERENCES Lardeaux, J. M., & Spalla, M. I. (1991). From granulites to eclogites in the Sesia zone (Italian Western Alps): A record of the opening and closure of the Piedmont ocean. Journal of Metamorphic Geology, 9, 35-59. Regis, D., Rubatto, D., Darling, J., Cenki-Tok, B., Zucali, M., & Engi, M. (2014). Multiple metamorphic stages within an eclogite-facies terrane (Sesia Zone, Western Alps) revealed by Th-U-Pb petrochronology. Journal of Petrology, 55(7), 1429-1456. Robyr, M., Darbellay, B., & Baumgartner, L. P. (2014). Matrix-dependent garnet growth in polymetamorphic rocks of the Sesia zone, Italian Alps. Journal of Metamorphic Geology, 32(1), 3-24.

  19. Lessons learned from oxygen isotopes in modern precipitation applied to interpretation of speleothem records of paleoclimate from eastern Asia

    Science.gov (United States)

    Dayem, Katherine E.; Molnar, Peter; Battisti, David S.; Roe, Gerard H.

    2010-06-01

    Variability in oxygen isotope ratios collected from speleothems in Chinese caves is often interpreted as a proxy for variability of precipitation, summer precipitation, seasonality of precipitation, and/or the proportion of 18O to 16O of annual total rainfall that is related to a strengthening or weakening of the East Asian monsoon and, in some cases, to the Indian monsoon. We use modern reanalysis and station data to test whether precipitation and temperature variability over China can be related to changes in climate in these distant locales. We find that annual and rainy season precipitation totals in each of central China, south China, and east India have correlation length scales of ∼ 500 km, shorter than the distance between many speleothem records that share similar long-term time variations in δ18O values. Thus the short distances of correlation do not support, though by themselves cannot refute, the idea that apparently synchronous variations in δ18O values at widely spaced (> 500 km) caves in China are due to variations in annual precipitation amounts. We also evaluate connections between climate variables and δ18O values using available instrumental measurements of δ18O values in precipitation. These data, from stations in the Global Network of Isotopes in Precipitation (GNIP), show that monthly δ18O values generally do not correlate well with either local precipitation amount or local temperature, and the degree to which monthly δ18O values do correlate with them varies from station to station. For the few locations that do show significant correlations between δ18O values and precipitation amount, we estimate the differences in precipitation amount that would be required to account for peak-to-peak differences in δ18O values in the speleothems from Hulu and Dongge caves, assuming that δ18O scales with the monthly amount of precipitation or with seasonal differences in precipitation. Insofar as the present-day relationship between δ18O

  20. Lead isotopes in deep-sea coral skeletons: Ground-truthing and a first deglacial Southern Ocean record

    Science.gov (United States)

    Wilson, David J.; van de Flierdt, Tina; Adkins, Jess F.

    2017-05-01

    Past changes in seawater lead (Pb) isotopes record the temporal evolution of anthropogenic pollution, continental weathering inputs, and ocean current transport. To advance our ability to reconstruct this signature, we present methodological developments that allow us to make precise and accurate Pb isotope measurements on deep-sea coral aragonite, and apply our approach to generate the first Pb isotope record for the glacial to deglacial mid-depth Southern Ocean. Our refined methodology includes a two-step anion exchange chemistry procedure and measurement using a 207Pb-204Pb double spike on a Thermo Finnigan Triton TIMS instrument. By employing a 1012 Ω resistor (in place of a 1011 Ω resistor) to measure the low-abundance 204Pb ion beam, we improve the internal precision on 206,207,208Pb/204Pb for a 2 ng load of NIST-SRM-981 Pb from typically ∼420 ppm to ∼230 ppm (2 s.e.), and the long term external reproducibility from ∼950 ppm to ∼550 ppm (2 s.d.). Furthermore, for a typical 500 mg coral sample with low Pb concentrations (∼6-10 ppb yielding ∼3-5 ng Pb for analysis), we obtain a comparable internal precision of ∼150-250 ppm for 206,207,208Pb/204Pb, indicating a good sensitivity for tracing natural Pb sources to the oceans. Successful extraction of a seawater signal from deep-sea coral aragonite further relies on careful physical and chemical cleaning steps, which are necessary to remove anthropogenic Pb contaminants and obtain results that are consistent with ferromanganese crusts. Applying our approach to a collection of late glacial and deglacial corals (∼12-40 ka BP) from south of Tasmania at ∼1.4-1.7 km water depth, we generated the first intermediate water Pb isotope record from the Southern Ocean. That record reveals millennial timescale variability, controlled by binary mixing between two Pb sources, but no distinct glacial-interglacial Pb isotope shift. Mixing between natural endmembers is fully consistent with our data and points to

  1. High-resolution conodont oxygen isotope record of Ordovician climate change

    Science.gov (United States)

    Chen, J.; Chen, Z.; Algeo, T. J.

    2013-12-01

    The Ordovician Period was characterized by several major events, including a prolonged 'super greenhouse' during the Early Ordovician, the 'Great Ordovician Biodiversification Event (GOBE)' of the Middle and early Late Ordovician, and the Hirnantian ice age and mass extinction of the latest Ordovician (Webby et al., 2004, The Great Ordovician Biodiversification Event, Columbia University Press). The cause of the rapid diversification of marine invertebrates during the GOBE is not clear, however, and several scenarios have been proposed including widespread development of shallow cratonic seas, strong magmatic and tectonic activity, and climate moderation. In order to investigate relationships between climate change and marine ecosystem evolution during the Ordovician, we measured the oxygen isotopic composition of single coniform conodonts using a Cameca secondary ion mass spectrometer. Our δ18O profile shows a shift at the Early/Middle Ordovician transition that is indicative of a rapid 6 to 8 °C cooling. This cooling event marks the termination of the Early Ordovician 'super greenhouse' and may have established cooler tropical seawater temperatures that were more favorable for invertebrate animals, setting the stage for the GOBE. Additional cooling episodes occurred during the early Sandbian, early Katian, and Hirnantian, the last culminating in a short-lived (extinction. Our results differ from those of Trotter et al. (2008, 'Did cooling oceans trigger Ordovician biodiversification? Evidence from conodont thermometry,' Science 321:550-554). Instead of a slow, protracted cooling through the Early and Middle Ordovician, our high-resolution record shows that cooling occurred in several discrete steps, with the largest step being at the Early/Middle Ordovician transition.

  2. Lateglacial and Holocene climatic changes in south-eastern Patagonia inferred from carbonate isotope records of Laguna Potrok Aike (Argentina)

    Science.gov (United States)

    Oehlerich, M.; Mayr, C.; Gussone, N.; Hahn, A.; Hölzl, S.; Lücke, A.; Ohlendorf, C.; Rummel, S.; Teichert, B. M. A.; Zolitschka, B.

    2015-04-01

    First results of strontium, calcium, carbon and oxygen isotope analyses of bulk carbonates from a 106 m long sediment record of Laguna Potrok Aike, located in southern Patagonia are presented. Morphological and isotopic investigations of μm-sized carbonate crystals in the sediment reveal an endogenic origin for the entire Holocene. During this time period the calcium carbonate record of Laguna Potrok Aike turned out to be most likely ikaite-derived. As ikaite precipitation in nature has only been observed in a narrow temperature window between 0 and 7 °C, the respective carbonate oxygen isotope ratios serve as a proxy of hydrological variations rather than of palaeotemperatures. We suggest that oxygen isotope ratios are sensitive to changes of the lake water balance induced by intensity variations of the Southern Hemisphere Westerlies and discuss the role of this wind belt as a driver for climate change in southern South America. In combination with other proxy records the evolution of westerly wind intensities is reconstructed. Our data suggest that weak SHW prevailed during the Lateglacial and the early Holocene, interrupted by an interval with strengthened Westerlies between 13.4 and 11.3 ka cal BP. Wind strength increased at 9.2 ka cal BP and significantly intensified until 7.0 ka cal BP. Subsequently, the wind intensity diminished and stabilised to conditions similar to present day after a period of reduced evaporation during the "Little Ice Age". Strontium isotopes (87Sr/86Sr ratio) were identified as a potential lake-level indicator and point to a lowering from overflow conditions during the Glacial (∼17 ka cal BP) to lowest lake levels around 8 ka cal BP. Thereafter the strontium isotope curve resembles the lake-level curve which is stepwise rising until the "Little Ice Age". The variability of the Ca isotope composition of the sediment reflects changes in the Ca budget of the lake, indicating higher degrees of Ca utilisation during the period with

  3. Paired carbon stable-isotope records for the Cenomanian Stage (100.5 -93.9 Ma): correlation tool and Late Cretaceous pCO2 record?

    Science.gov (United States)

    Jarvis, Ian; Gröcke, Darren; Laurin, Jiří; Selby, David; Roest-Ellis, Sascha; Miles, Andrew; Lignum, John; Gale, Andrew; Kennedy, Jim

    2016-04-01

    Carbon stable-isotope stratigraphy of marine carbonates (δ13Ccarb) provides remarkable insights into past variation in the global carbon cycle, and has become firmly established as a powerful global correlation tool. Continuous δ13Ccarb time series are becoming increasingly available for much of the geological record, including the Upper Cretaceous. However, our knowledge of stratigraphic variation in the carbon isotopic composition of sedimentary organic matter (δ13Corg) is much poorer, and is generally restricted to organic-rich sedimentary successions and/or key boundary intervals. Close coupling exists between the global isotopic composition of the reduced and oxidised carbon reservoirs on geological time scales, but the stratigraphic resolution of most long-term δ13Corg Mesozoic records is inadequate to identify leads and lags in the responses of the two reservoirs to carbon cycle perturbations. Cenomanian times (100.5-93.9 Ma) represent perhaps the best documented episode of eustatic rise in sea level in Earth history and the beginning of the Late Mesozoic thermal maximum, driving global expansion of epicontinental seas and the onset of widespread pelagic and hemipelagic carbonate deposition. Significant changes occurred in global stable-isotope records, including two prominent perturbations of the carbon cycle - the Mid-Cenomanian Event I (MCEI; ~96.5-96.2 Ma) and Oceanic Anoxic Event 2 (OAE2; ~94.5-93.8 Ma). OAE2, one of two truly global Cretaceous OAEs, was marked by the widespread deposition of black shales, and a global positive carbon stable-isotope excursion of 2.0 - 2.5‰ δ13Ccarb, and up to 7‰ in the sulphur-bound phytane biomarker. MCEI, by contrast, shows a English Chalk reference section at Folkestone, and correlate the carbon-isotope events between England, France, Germany and Italy. Comparison of the Vergons δ13Ccarb vs. δ13Corg profiles demonstrates similar medium-term stratigraphic variation, but significant differences in both short

  4. Tertiary climate records from arid areas as indicated by isotopic signature of alunite

    International Nuclear Information System (INIS)

    Arehart, G.B.

    1997-01-01

    Alunite (ideally KAl 3 (SO 4 ) 2 (OH) 6 ] is a relatively common mineral in some hydrothermal systems as well as in the weathering environment in arid regions. Because of its composition, alunite is an ideal mineral for use in stable isotopic studies of all types. In particular, there is little or no hydrogen isotope fractionation between alunite formed at surficial temperatures and water from which it forms. Therefore, the isotopic composition (delta D) of this mineral reflect the isotopic composition of meteoric waters at the time of deposition, which can in turn be utilised to infer paleoclimatic information. In addition, the presence of K (and its decay products) allows simple and accurate determination of absolute ages for mineral deposition making alunite one of very few paleoclimate indicators that is directly datable. (author)

  5. An eclogitic diamond from Mir pipe (Yakutia), recording two growth events from different isotopic sources

    NARCIS (Netherlands)

    Bulanova, G.P.; Wiggers de Vries, D.F.; Pearson, D.G.; Beard, A.; Mikhail, S.; Smelov, A.P.; Davies, G.R.

    2014-01-01

    An eclogitic octahedral macrodiamond from the Mir kimberlite (Yakutia) has a complex growth structure with distinctive core, intermediate and rim zones. Carbon isotope ratios change abruptly from depleted δ

  6. The origin and evolution of chondrites recorded in the elemental and isotopic compositions of their macromolecular organic matter

    Science.gov (United States)

    Alexander, C. M. O.'D.; Fogel, M.; Yabuta, H.; Cody, G. D.

    2007-09-01

    Extraterrestrial organic matter in meteorites potentially retains a unique record of synthesis and chemical/thermal modification by parent body, nebular and even presolar processes. In a survey of the elemental and isotopic compositions of insoluble organic matter (IOM) from 75 carbonaceous, ordinary and enstatite chondrites, we find dramatic variations within and between chondrite classes. There is no evidence that these variations correlate with the time and/or location of chondrite formation, or with any primary petrologic or bulk compositional features that are associated with nebular processes (e.g., chondrule and volatile trace element abundances). Nor is there evidence for the formation of the IOM by Fischer-Tropsch-Type synthesis in the nebula or in the parent bodies. The elemental variations are consistent with thermal maturation and/or oxidation of a common precursor. For reasons that are unclear, there are large variations in isotopic composition within and between chondrite classes that do not correlate in a simple way with elemental composition or petrologic type. Nevertheless, because of the pattern of elemental variations with petrologic type and the lack of any correlation with the primary features of the chondrite classes, at present the most likely explanation is that all IOM compositional variations are the result of parent body processing of a common precursor. If correct, the range of isotopic compositions within and between chondrite classes implies that the IOM is composed of several isotopically distinct components whose relative stability varied with parent body conditions. The most primitive IOM is found in the CR chondrites and Bells (CM2). Isotopically, the IOM from these meteorites resembles the IOM in interplanetary dust particles. Chemically, their IOM resembles the CHON particles of comet Halley. Despite the large isotopic anomalies in the IOM from these meteorites, it is uncertain whether the IOM formed in the interstellar medium or

  7. Geochemistry contribution of Pb isotopes on basalts origin study from Parana basin, Brazil

    International Nuclear Information System (INIS)

    Marques, L.S.; Dupre, B.; Allegre, C.J.

    1990-01-01

    This paper presents thirty new Pb-isotope and concentration data for low- and high-tiO sub(2) continental flood basalts of the Parana Basin. The results obtained from representative samples show significant differences with respect to type and location of these basic rocks. The low- and high-TiO sub(2) basalts from the northern region of the Parana Basin exhibit very similar Pb-isotope compositions. On the other hand, the low-TiO sub(2) basalts of central and southern areas, which exhibit low Sr initial isotope ratios (less than 0,7060), show very small variation in Pb isotope compositions which are highly enriched in radiogenic Pb in comparison with the analogues of northern region. The high-TiO sub(2) basic rocks analysed from northern and central regions have the same values for Pb isotope ratios, which are slightly more radiogenic compared with high-TiO sub(2) basalts from southern region. The data obtained, combined with other geochemical (major and trace elements, including rare earths) and isotope (Sr and Nd) results support the view that the basalts from northern and southern areas of the Parana Basin originated in lithospheric mantle reservoirs with different geochemical characteristics. (author)

  8. Estimation of snow and glacier melt contribution to Liddar stream in a mountainous catchment, western Himalaya: an isotopic approach.

    Science.gov (United States)

    Jeelani, Gh; Shah, Rouf A; Jacob, Noble; Deshpande, Rajendrakumar D

    2017-03-01

    Snow- and glacier-dominated catchments in the Himalayas are important sources of fresh water to more than one billion people. However, the contribution of snowmelt and glacier melt to stream flow remains largely unquantified in most parts of the Himalayas. We used environmental isotopes and geochemical tracers to determine the source water and flow paths of stream flow draining the snow- and glacier-dominated mountainous catchment of the western Himalaya. The study suggested that the stream flow in the spring season is dominated by the snowmelt released from low altitudes and becomes isotopically depleted as the melt season progressed. The tracer-based mixing models suggested that snowmelt contributed a significant proportion (5-66 %) to stream flow throughout the year with the maximum contribution in spring and summer seasons (from March to July). In 2013 a large and persistent snowpack contributed significantly (∼51 %) to stream flow in autumn (September and October) as well. The average annual contribution of glacier melt to stream flow is little (5 %). However, the monthly contribution of glacier melt to stream flow reaches up to 19 % in September during years of less persistent snow pack.

  9. Constraining the cause of the end-Guadalupian extinction with coupled records of carbon and calcium isotopes

    Science.gov (United States)

    Jost, A. B.; Mundil, R.; He, B.; Brown, S. T.; Altiner, D.; Sun, Y.; DePaolo, D. J.; Payne, J.

    2013-12-01

    A negative δ13C excursion in carbonate sediments from Guadalupian (Middle Permian) and Lopingian (Late Permian) stratigraphic sections has been interpreted to result from a large carbon cycle disturbance during end-Guadalupian extinction event (ca. 260 Ma). However, the carbon isotope data alone are insufficient to uniquely determine the type and magnitude of perturbations to the global carbon cycle. The carbon and calcium cycles are coupled via CaCO3 burial, so changes in calcium isotopes can be used to constrain the cause of a carbon isotope excursion. In this study, we present coupled carbon and calcium isotope records from three Guadalupian-Lopingian (G/L) sections in China and Turkey. Isotope records among our studied sections are inconsistent in both their δ13C and δ44/40Ca records. Similar inconsistencies in δ13C among sections occur across previously published datasets. Sections with large (>3‰) changes in δ13C either show evidence for diagenetic alteration or do not show δ13C and δ44/40Ca changes consistent with severe volcanic degassing from Emeishan or methane clathrate destabilization. We conclude that the large isotopic changes are more likely the result of local burial conditions or diagenetic effects, rather than a large carbon cycle disturbance. Perturbations to the global carbon and calcium cycles appear to have been much smaller across the G/L transition than across the subsequent Permian-Triassic boundary. This finding is consistent with recent paleobiological data showing that the end-Guadalupian extinction was much less severe than previously believed, and was indistinguishable in magnitude from background intervals. However, selective extinction of marine animals with passive respiratory physiology indicates that the G/L extinction cannot simply be due to background extinction or sampling failure, and that it was triggered by some environmental event. Therefore, any environmental event must have been small enough to not generate large

  10. Spatial and temporal variation in tree-ring α-cellulose oxygen and hydrogen isotope values as a record of water availability in the Atacama Desert

    Science.gov (United States)

    Olson, E. J.; Dodd, J. P.

    2015-12-01

    Previous studies have documented that tree ring oxygen and hydrogen isotopes primarily reflect source water; however, biosynthetic fractionation processes modify this signal and can have a varied response to environmental conditions. The degree to which source water contributes to δ2H and δ18O values of plant α-cellulose is species-specific and modern calibration studies are necessary. Here we present a calibration data set of P. tamarugo α-cellulose δ2H and δ18O values from the Atacama Desert in Northern Chile. P. tamarugo trees are endemic to the region and have adapted to the extremely arid environment where average annual precipitation is 2 ‰ over the past 20 years associated with a ~1.1 m lowering of the local groundwater table throughout the area. The correlation between a-cellulose isotope values and hydrologic conditions in modern times provides a baseline for interpretation of tree-ring isotope chronologies from the past 9.5 kya. A high-resolution Holocene (1.8-9.1 kya) age record of Prosopis sp. tree ring α-cellulose δ18O values provides a proxy for climatic and hydrologic conditions. During the early Holocene δ18O values range from 31 to 35‰ (2σ=0.58‰), while during the late Holocene values are much more variable (27.4 to 41‰; 2σ=2.64‰). Anthropogenic demand on local water sources is the most significant environmental factor affecting the variation in modern α-cellulose δ18O values; however, climate induced changes in regional water availability are the dominant driver of variability in the paleo-record. Increased variability in α-cellulose δ18O values in the late Holocene most likely indicates a reduction in annual recharge and an increase in episodic flood events driven by ENSO and other modes of atmospheric variability.

  11. Biomarker and stable carbon isotopic signatures for 100–200 year sediment record in the Chaihe catchment in southwest China

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yanhua, E-mail: wangyanhua@njnu.edu.cn [School of Geography Science, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023 (China); Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application (China); Yang, Hao [School of Geography Science, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023 (China); Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control (China); Zhang, Jixiang [College of Economics and Management, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Baixia, Nanjing 210016 (China); Xu, Meina; Wu, Changbin [School of Geography Science, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023 (China)

    2015-01-01

    Natural inputs and anthropogenic influences on lakes and their catchments are reflected in the sediment record. In the present study, the extractable organic compounds from sediments in the Chaihe catchment of the Dianchi watershed were analyzed to characterize source inputs. Results show that the sediments are dominated by odd numbered n-alkanes (n-C{sub 16}–n-C{sub 33}), maximizing at n-C{sub 17}, n-C{sub 29} and n-C{sub 31}. Aliphatic hydrocarbon may be composed of terrestrial plants and bacteria. The values of δ{sup 13}C{sub 27}, δ{sup 13}C{sub 29} and δ{sup 13}C{sub 31} of n-alkanes exhibit a range from − 33.27‰ to − 25.46‰, from − 35.76‰ to − 28.47‰ and from − 33.67‰ to − 27.42‰, respectively and three records strongly covary with depth, falling within the range of C{sub 3} plants in the study area. An isotopic model revealed C{sub 3} plant contribution to sedimentary organic matter (OM) ranging from 40.75% to 97.22%. The values of ACL{sub 27–33}, CPI{sub 27–33}, OEP, Paq, Pr/Ph, (C{sub 27} + C{sub 29})/2C{sub 31}, (C{sub 21} + C{sub 23} + C{sub 25})/3C{sub 17} and nC{sub 26}{sup −}/nC{sub 27}{sup +} are consistent with the C{sub 3} plant predominance. A constant CRS model gave the accumulation rates ranging from 2.69 to 8.46 mm a{sup −1} spanning 1885–2010. It was concluded that OM transport in the Chaihe catchment was influenced strongly by human activities resulting in enhanced eutrophication. - Highlights: • Strong predominance of odd-numbered n-alkanes maximized at n-C{sub 17}, n-C{sub 29} and n-C{sub 31} • Sedimentary OM in the Chaihe catchment was deduced mainly from C{sub 3} plants. • Human activities enhanced OM transport, resulting in worse ecosystem.

  12. Hf Isotope Evidence for Subducted Basalt and Sediment Contributions to the Eastern Trans-Mexican Volcanic Belt

    Science.gov (United States)

    Cai, Y.; Tuena, A. G.; Capra, L.; Straub, S. M.; Goldstein, S. L.; Langmuir, C. H.

    2005-12-01

    Magmas generated at thick crust continental arcs often have enriched continental crust-like trace element patterns and Pb-Sr-Nd isotope ratios that are intermediate to both upper mantle and crustal compositions. Thus it is difficult to distinguish between contributions from (a) the subducted basalt and the upper mantle wedge, and (b) subducted sediment and the continental crust. These issues have been the focus of major controversy. Here we show evidence for subduction contributions to lavas in a classic thick crust environment. In Eastern Trans-Mexican Volcanic Belt, the upper continental crust is 30 km to 45 km thick. However, primitive mafic lavas erupt on many sites across the arc. We have analyzed the subducting sediments as represented by DSDP 487, located seaward of the trench, where the lower third of the sediment column has strongly hydrothermal pelagic features and the upper two-thirds is composed of terrigenous sediments. The pelagic sediments have distinctive features that could be used to identify a subduction component in the volcanics, including high REE/Hf, negative Ce anomalies, and Nd-Hf isotopes that lie on the "seawater array" and offset from the "mantle-crust" array. We have focused on a unique series of lavas from volcano Nevado de Toluca, located southwest of Mexico City. These lavas show negative Ce anomalies coupled with low REE/Hf and Zr/Nd ratios. Hf-Nd isotope ratios show a shallow trend compared to the mantle-crust array, consistent with a pelagic component. In addition, Hf isotopes show a striking positive correlation with Ce anomalies that trend toward the pelagic sediment compositions. These and other observations provide clear evidence for a component from subducted sediment in the lavas. In addition, there is a negative correlation of Lu/Hf and Hf isotopes that requires a mixing endmember with MORB-like Hf isotope ratios but with lower than MORB Lu/Hf. This indicates a melt from eclogitic subducted basalt. Compared to other

  13. Contribution of records management to audit opinions and accountability in government

    Directory of Open Access Journals (Sweden)

    Rodreck David

    2017-05-01

    Full Text Available Background: Auditing can support national democratic processes, national development and government good will. Supreme Audit Institutions (SAI, such as offices of Auditor General, publish consolidated reports on audit outcomes for local authorities, government departments, parastatals and related public entities. These reports identify broad areas analysed during audit exercises that often include financial management, governance, asset management, risk management, revenue collection and debt recovery. They highlight trends that were detected during audit exercises at the end of a financial year. The reports further show how records and records management affect audit exercises as well as financial management within the audited institutions. Objectives: The intention of the research was to ascertain the contribution of records management to audit opinions and accountability in financial management in Zimbabwean government entities. Method: A document analysis of Comptroller and Auditor General of Zimbabwe (CAGZ’s reports was used to identify the types of decisions and recommendations (audit opinions issued, in juxtaposition to the records management issues raised. Results and Conclusion: This study shows that there is a strong correlation between records management concerns and audit opinions raised by the CAGZ’s narrative audit reports. Inadequate records management within government entities was associated with adverse and qualified opinions and, in some cases, unqualified opinions that had emphases of matter. There was a causal loop in which lack of documentary evidence of financial activities was the source cause of poor accounting and poor audit reports. Errors resulting from incomplete or inaccurate records meant that government entities were not showing a true picture of their financial status and their financial statements could be materially misstated. As an important monitoring and control system, records management should be

  14. Contribution of Electronic Medical Records to the Management of Rare Diseases

    Directory of Open Access Journals (Sweden)

    Dominique Bremond-Gignac

    2015-01-01

    Full Text Available Purpose. Electronic health record systems provide great opportunity to study most diseases. Objective of this study was to determine whether electronic medical records (EMR in ophthalmology contribute to management of rare eye diseases, isolated or in syndromes. Study was designed to identify and collect patients’ data with ophthalmology-specific EMR. Methods. Ophthalmology-specific EMR software (Softalmo software Corilus was used to acquire ophthalmological ocular consultation data from patients with five rare eye diseases. The rare eye diseases and data were selected and collected regarding expertise of eye center. Results. A total of 135,206 outpatient consultations were performed between 2011 and 2014 in our medical center specialized in rare eye diseases. The search software identified 29 congenital aniridia, 6 Axenfeld/Rieger syndrome, 11 BEPS, 3 Nanophthalmos, and 3 Rubinstein-Taybi syndrome. Discussion. EMR provides advantages for medical care. The use of ophthalmology-specific EMR is reliable and can contribute to a comprehensive ocular visual phenotype useful for clinical research. Conclusion. Routinely EMR acquired with specific software dedicated to ophthalmology provides sufficient detail for rare diseases. These software-collected data appear useful for creating patient cohorts and recording ocular examination, avoiding the time-consuming analysis of paper records and investigation, in a University Hospital linked to a National Reference Rare Center Disease.

  15. Contribution of Electronic Medical Records to the Management of Rare Diseases.

    Science.gov (United States)

    Bremond-Gignac, Dominique; Lewandowski, Elisabeth; Copin, Henri

    2015-01-01

    Electronic health record systems provide great opportunity to study most diseases. Objective of this study was to determine whether electronic medical records (EMR) in ophthalmology contribute to management of rare eye diseases, isolated or in syndromes. Study was designed to identify and collect patients' data with ophthalmology-specific EMR. Ophthalmology-specific EMR software (Softalmo software Corilus) was used to acquire ophthalmological ocular consultation data from patients with five rare eye diseases. The rare eye diseases and data were selected and collected regarding expertise of eye center. A total of 135,206 outpatient consultations were performed between 2011 and 2014 in our medical center specialized in rare eye diseases. The search software identified 29 congenital aniridia, 6 Axenfeld/Rieger syndrome, 11 BEPS, 3 Nanophthalmos, and 3 Rubinstein-Taybi syndrome. EMR provides advantages for medical care. The use of ophthalmology-specific EMR is reliable and can contribute to a comprehensive ocular visual phenotype useful for clinical research. Routinely EMR acquired with specific software dedicated to ophthalmology provides sufficient detail for rare diseases. These software-collected data appear useful for creating patient cohorts and recording ocular examination, avoiding the time-consuming analysis of paper records and investigation, in a University Hospital linked to a National Reference Rare Center Disease.

  16. McCall Glacier record of Arctic climate change: Interpreting a northern Alaska ice core with regional water isotopes

    Science.gov (United States)

    Klein, E. S.; Nolan, M.; McConnell, J.; Sigl, M.; Cherry, J.; Young, J.; Welker, J. M.

    2016-01-01

    We explored modern precipitation and ice core isotope ratios to better understand both modern and paleo climate in the Arctic. Paleoclimate reconstructions require an understanding of how modern synoptic climate influences proxies used in those reconstructions, such as water isotopes. Therefore we measured periodic precipitation samples at Toolik Lake Field Station (Toolik) in the northern foothills of the Brooks Range in the Alaskan Arctic to determine δ18O and δ2H. We applied this multi-decadal local precipitation δ18O/temperature regression to ∼65 years of McCall Glacier (also in the Brooks Range) ice core isotope measurements and found an increase in reconstructed temperatures over the late-20th and early-21st centuries. We also show that the McCall Glacier δ18O isotope record is negatively correlated with the winter bidecadal North Pacific Index (NPI) climate oscillation. McCall Glacier deuterium excess (d-excess, δ2H - 8*δ18O) values display a bidecadal periodicity coherent with the NPI and suggest shifts from more southwestern Bering Sea moisture sources with less sea ice (lower d-excess values) to more northern Arctic Ocean moisture sources with more sea ice (higher d-excess values). Northern ice covered Arctic Ocean McCall Glacier moisture sources are associated with weak Aleutian Low (AL) circulation patterns and the southern moisture sources with strong AL patterns. Ice core d-excess values significantly decrease over the record, coincident with warmer temperatures and a significant reduction in Alaska sea ice concentration, which suggests that ice free northern ocean waters are increasingly serving as terrestrial precipitation moisture sources; a concept recently proposed by modeling studies and also present in Greenland ice core d-excess values during previous transitions to warm periods. This study also shows the efficacy and importance of using ice cores from Arctic valley glaciers in paleoclimate reconstructions.

  17. Isotope dilution mass spectrometry: What can it contribute to accuracy in trace analysis?

    International Nuclear Information System (INIS)

    Bievre, P. de

    1990-01-01

    IDMS uses the fact that the isotopes are much better 'representatives' of an element than the average chemical atom and their numbers can be measured better in a more physical measurement than in a classicial chemical measurement where atoms are involved. (orig./EF)

  18. Contribution of isotope techniques to evaluate water resources in the Peruvian Altiplano

    International Nuclear Information System (INIS)

    Araguas, L.; Arroyo, C.; Palza, G.; Rojas, R.; Romero, J.; Silar, J.

    1999-01-01

    Environmental isotopes H , 18 O, 13 C, 3 H, and 14 C were regularly measured in precipitation, surface, and ground water to investigate a series of problems linked with the management of water resources in the Peruvian Altiplano, a plateau located in Southern Peru

  19. Estimation and calibration of the water isotope differential diffusion length in ice core records

    NARCIS (Netherlands)

    van der Wel, G.; Fischer, H.; Oerter, H.; Meyer, H.; Meijer, H. A. J.

    2015-01-01

    Palaeoclimatic information can be retrieved from the diffusion of the stable water isotope signal during firnification of snow. The diffusion length, a measure for the amount of diffusion a layer has experienced, depends on the firn temperature and the accumulation rate. We show that the estimation

  20. An isotopic approach to study the recharge mechanism in Haripur plain contribution to the area from Tarbela and Khanpur lakes

    International Nuclear Information System (INIS)

    Sajjad, M.I.; Tasneem, M.A.; Khan, I.H.; Ahmad, M.; Akram, W.

    1992-01-01

    Environmental isotopic investigation were carried out in Haripur plain to determine the recharge mechanism in the area. The Haripur plain is bounded by river Doar (that falls in Tarbela lake) in the north mountain ranges in the east and west, while the river Haro flows on the south eastern boundary upon which Khanpur dam has been built. Effort were made to identify the different sources which recharge the aquifer in the area. Isotopic data reveals that the major source of recharge is the rainfall on adjoining hills There is no contribution of Tarbela and Khanpur lakes. The residence time varies from a few years to more than fifty years depending upon the geology of the area. 14 figs. (author)

  1. Sr-Pb-Nd isotopic evidence that both MORB and OIB sources contribute to oceanic island arc magmas in Fiji

    International Nuclear Information System (INIS)

    Gill, J.B.

    1984-01-01

    Twenty-eight new Pb, 20 Sr, and 9 Nd isotopic compositions are presented for 32 rocks and one galena from Fiji and the South Fiji (back-arc) Basin. The Fijian rocks range in age from 35 to 143 Nd/ 144 Nd and low 206 Pb/ 204 Pb). Nearly constant 207 Pb/ 204 Pb, and an OIB source component lying within the conventional Sr-Nd-Pb mantle array. In later calc-alkaline and shoshonitic series rocks, these same trace element and isotopic ratios are more like those of OIB. The change was not accompanied by an increase in 207 Pb/ 204 Pb or Cs/K, indeed, 207 Pb/ 204 Pb is closer to the mantle array in these later series. Consequently, the change indicates a greater contribution from OIB sources, rather than from recycled ocean crust. These interpretations require that both MORB and OIB sources coexist in the uppermost mantle above subducted lithosphere. (orig./WB)

  2. The isotopic record of atmospheric lead fall-out on an Icelandic salt marsh since AD 50

    International Nuclear Information System (INIS)

    Marshall, William A.; Clough, Robert; Gehrels, W. Roland

    2009-01-01

    We report a record of atmospheric Pb deposition at a coastal site in western Iceland that spans the last two millennia. The elemental concentrations of Pb, Al, Li and Ti are determined using ICP-MS from a sediment monolith collected from a salt marsh. Multicollector (MC) ICP-MS analysis is used to obtain isotopic ratios of stable Pb. The Pb/Ti and Pb/Li ratios are used to separate natural Pb background concentrations from Pb derived from remote anthropogenic sources. The pollution record in western Iceland is subdued in comparison with Pb records from the European mainland, but the isotopic character, profile and timing of Pb deposition show good agreement with the atmospheric Pb fall-out reported from sites in Scandinavia and northwestern Europe. At the bottom of the sequence we isolate a low-level (0.1-0.4 mg kg -1 ) Pb enrichment signal dated to AD 50-150. The isotopic signature and timing of this signal suggest Roman metal working industries as the source. In the subsequent millennium there was no significant or very low (i.e. elemental concentrations -1 ) anthropogenic Pb deposition at the site up to, and including, the early Medieval period. Above a pumice layer, dated to AD 1226-1227, a small increase in Pb deposition is found. This trend is maintained until a more substantive and progressive increase is signalled during the late 1700s and early 1800s. This is followed by a substantial enrichment signal in the sediments (> 3.0 mg kg -1 ) that is interpreted as derived from industrial coal burning and metal working during the 19th and 20th centuries in northern Europe. During the late 20th century, significant fall-out from European fuel additives reached Iceland

  3. Effects of ocean acidification on the marine calcium isotope record at the Paleocene-Eocene Thermal Maximum

    Science.gov (United States)

    Griffith, Elizabeth M.; Fantle, Matthew S.; Eisenhauer, Anton; Paytan, Adina; Bullen, Thomas D.

    2015-06-01

    Carbonates are used extensively to reconstruct paleoclimate and paleoceanographic conditions over geologic time scales. However, these archives are susceptible to diagenetic alteration via dissolution, recrystallization and secondary precipitation, particularly during ocean acidification events when intense dissolution can occur. Despite the possible effects of diagenesis on proxy fidelity, the impacts of diagenesis on the calcium isotopic composition (δ44Ca) of carbonates are unclear. To shed light on this issue, bulk carbonate δ44Ca was measured at high resolution in two Pacific deep sea sediment cores (ODP Sites 1212 and 1221) with considerably different dissolution histories over the Paleocene-Eocene Thermal Maximum (PETM, ∼ 55 Ma). The δ44Ca of marine barite was also measured at the deeper Site 1221, which experienced severe carbonate dissolution during the PETM. Large variations (∼ 0.8 ‰) in bulk carbonate δ44Ca occur in the deeper of the two sites at depths corresponding to the peak carbon isotope excursion, which correlate with a large drop in carbonate weight percent. Such an effect is not observed in either the 1221 barite record or the bulk carbonate record at the shallower Site 1212, which is also less affected by dissolution. We contend that ocean chemical changes associated with abrupt and massive carbon release into the ocean-atmosphere system and subsequent ocean acidification at the PETM affected the bulk carbonate δ44Ca record via diagenesis in the sedimentary column. Such effects are considerable, and need to be taken into account when interpreting Ca isotope data and, potentially, other geochemical proxies over extreme climatic events that drive sediment dissolution.

  4. Oxygen isotope records of Globigerina bulloides across a north-south transect in the south-western Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Khare, N.; Chaturvedi, S.K.; Saraswat, R

    , Washington, D.C). Lutjeharms, J.R.E., N.M. Walters and B.R. Allanson. 1985. Oceanic frontal systems and biologicalenhancement. p.11-21. In: Antarctic Nutrient Cycles and Food Webs. ed. by W.R. Siegfried et al., Springer-Verlag, NewYork. Matsumoto, K., J...: Ocean Sci. J.: 44(2); 2009; 117-123 OXYGEN ISOTOPE RECORDS OF GLOBIGERINA BULLOIDES ACROSS A NORTH-SOUTH TRANSECT IN THE SOUTH-WESTERN INDIAN OCEAN N. Khare 1* , S. K. Chaturvedi 2 and R. Saraswat 3 1. Ministry of Earth Sciences, Block...

  5. Speleothem stable isotope records for east-central Europe: resampling sedimentary proxy records to obtain evenly spaced time series with spectral guidance

    Science.gov (United States)

    Gábor Hatvani, István; Kern, Zoltán; Leél-Őssy, Szabolcs; Demény, Attila

    2018-01-01

    Uneven spacing is a common feature of sedimentary paleoclimate records, in many cases causing difficulties in the application of classical statistical and time series methods. Although special statistical tools do exist to assess unevenly spaced data directly, the transformation of such data into a temporally equidistant time series which may then be examined using commonly employed statistical tools remains, however, an unachieved goal. The present paper, therefore, introduces an approach to obtain evenly spaced time series (using cubic spline fitting) from unevenly spaced speleothem records with the application of a spectral guidance to avoid the spectral bias caused by interpolation and retain the original spectral characteristics of the data. The methodology was applied to stable carbon and oxygen isotope records derived from two stalagmites from the Baradla Cave (NE Hungary) dating back to the late 18th century. To show the benefit of the equally spaced records to climate studies, their coherence with climate parameters is explored using wavelet transform coherence and discussed. The obtained equally spaced time series are available at PANGAEA.875917" target="_blank">https://doi.org/10.1594/PANGAEA.875917.

  6. Carbon and nitrogen isotope variations in tree-rings as records of perturbations in regional carbon and nitrogen cycles.

    Science.gov (United States)

    Bukata, Andrew R; Kyser, T Kurtis

    2007-02-15

    Increasing anthropogenic pollution from urban centers and fossil fuel combustion can impact the carbon and nitrogen cycles in forests. To assess the impact of twentieth century anthropogenic pollution on forested system carbon and nitrogen cycles, variations in the carbon and nitrogen isotopic compositions of tree-rings were measured. Individual annual growth rings in trees from six sites across Ontario and one in New Brunswick, Canada were used to develop site chronologies of tree-ring delta 15N and delta 13C values. Tree-ring 615N values were approximately 0.5% per hundred higher and correlated with contemporaneous foliar samples from the same tree, but not with delta 15N values of soil samples. Temporal trends in carbon and nitrogen isotopic compositions of these tree-rings are consistent with increasing anthropogenic influence on both the carbon and nitrogen cycles since 1945. Tree-ring delta 13C values and delta 15N values are correlated at both remote and urban-proximal sites, with delta 15N values decreasing since 1945 and converging on 1% per hundred at urban-proximal sites and decreasing but not converging on a single delta 15N value in remote sites. These results indicate that temporal trends in tree-ring nitrogen and carbon isotopic compositions record the regional extent of pollution.

  7. Pb isotope evidence for contributions from different Iceland mantle components to Palaeogene East Greenland flood basalts

    DEFF Research Database (Denmark)

    Peate, David; Stecher, Ole

    2003-01-01

    We present new Pb isotope data on 21 samples of break-up-related flood basalts (56–54 Ma) from the Blosseville Kyst region of East Greenland. These samples show a considerable range in isotopic composition (206Pb/204Pb 17.6 to 19.3) that broadly correlates with compositional type. The ‘low-Ti’ type...... in the selected samples. Uncontaminated Palaeogene East Greenland flood basalts appear to have sampled the same broad range in mantle compositions seen in Recent Iceland basalts. In contrast to the peripheral lava suites from the British Isles and Southeast Greenland, where the inferred uncontaminated magmas have...... to the most radiogenic values found in recent Icelandic basalts. Furthermore, the main volume of lavas in East Greenland is displaced away from the NAEM towards this radiogenic Pb component. Thus, this ‘Iceland radiogenic Pb end-member’ component was a significant contributor to the break-up-related magmatism...

  8. Contribution to the structure study of mercury isotopes with the (p,d) reaction

    International Nuclear Information System (INIS)

    Grafeuille, S.

    1985-10-01

    The mercury isotopes were studied by means of the two pick-up reactions (p,d) and (p,t). Enriched targets of 204 Hg, 202 Hg, 201 Hg, 200 Hg, 199 Hg, 198 Hg and 196 Hg were bombarded by a 25 MeV proton beam from the Orsay MP tandem accelerator. Emitted particles were analyzed by a split-pole magnetic spectrometer. We present all the results (nearly 150 states) of the analysis of the (p,d) reactions. Our (p,d) and (p,t) study show new discontinuities around 200 Hg in systematics of mercury isotopes. Part of the results are compared to the U(5) limits of Interacting Bosons (and Fermions) Models. The light nuclei can be considered reasonably described but this could be somewhat fortuitous. (71 refs) [fr

  9. Contribution to the future prospects of laser separation of uranium isotopes

    International Nuclear Information System (INIS)

    Becker, F.S.

    1981-04-01

    In the past several years, the selective absorption of laser light has been considered as an alternative to the large-scale technical uranium isotope separation schemes based on the mass-dependence of the diffusion velocity or the centrifugal force. An analysis of the published results appears to show that two-frequency multiphoton dissociation is especially attractive for a technical process. To clarify the prospects of such a scheme, studies of the isotope selectivity of the multiphoton dissociation of statically cooled UF 6 with two infrared frequencies, one of which is tunable in the region of the UF 6 ν(3) band at 16 μm, are proposed. The construction and testing of a high-power laser, tunable in the 16 μm region, based on the frequency conversion of 10 μm CO 2 radiation by means of stimulated rotational Raman scattering in para-hydrogen, is described. Pulse-widths of about 80 nsec and pulse energies of about one half J are obtained which ought to permit, in combination with a CO 2 laser, the multiphoton dissociation of UF 6 without focussing. By means of UV-light experiments it is shown that optical dissociation of UF 6 can be obtained even in the presence of high F-concentrations, thus permitting a high dissociation yield without a F-scavenger which could negatively affect the isotope selectivity. (orig./HP) [de

  10. 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.

  11. Constraining the redox landscape of the mid-Proterozoic oceans: new insights from the carbonate uranium isotope record

    Science.gov (United States)

    Gilleaudeau, G. J.; Kaufman, A. J.; Luo, G.; Romaniello, S. J.; Zhang, F.; Kah, L. C.; Azmy, K.; Bartley, J. K.; Sahoo, S. K.; Knoll, A. H.; Anbar, A. D.

    2017-12-01

    The redox landscape of the global oceans during the prolonged period between the Great Oxidation Event (GOE) and the Neoproterozoic Oxygenation Event (NOE) is a topic of considerable debate. Data from local redox proxies such as iron speciation suggest largely ferruginous conditions in the subsurface oceans (with the exception of one report of oxic subsurface waters) and a variable degree of euxinia in shallow shelf and epeiric sea environments. There is general consensus that anoxia was more widespread than in the modern ocean, but quantifying the degree of seafloor anoxia is challenging given that most redox proxies are inherently local and/or based on the relatively sparse black shale record. Here, we present new uranium (U) isotope data from carbonate rocks than span the mid-Proterozoic Eon. U-isotopes operate as a proxy for seafloor anoxia because the δ238U value of seawater is largely controlled by the size of the anoxic/euxinic U sink, which preferentially removes isotopically heavy 238U, leaving the oceans enriched in 235U. Our compilation of data from mid-Proterozoic successions reveals δ238U values similar to modern seawater (-0.39 ± 0.19 ‰ [1 s.d.] for the Gaoyuzhuang, Angmaat, El Mreiti, Vazante, and Turukhansk successions spanning 1.5 to 0.9 Ga). Given the potential for an isotopic offset between carbonate minerals and seawater of up to 0.3 ‰, we suggest that mid-Proterozoic seawater had a δ238U value generally between -0.4 and -0.7 ‰, which is lower than modern seawater, but higher than has been inferred for intervals of expanded anoxia elsewhere in Earth history. These results are consistent with recently published U-isotope data from the 1.36 Ga Velkerri Formation, and suggest that large portions of the seafloor may have been covered by at least weakly oxygenated waters during the mid-Proterozoic Eon. Uncertainty remains, however, because the isotopic effects of the non-euxinic anoxic sink are poorly constrained. Nonetheless, our data

  12. Fossil isotope records of seasonal climate and ecology: Straight from the horse's mouth

    Science.gov (United States)

    Sharp, Z. D.; Cerling, T. E.

    1998-03-01

    Isotope analysis of a bulk fossil tooth gives a “snapshot” impression of paleoclimatic conditions—a single point in time. However, hypsodont teeth grow over a period of a year or more, so that stable carbon and oxygen isotope variations along their length are a “tape recorder” of short-term seasonal variations from the distant past. We have used a new in situ micro-laser sampling method to determine submillimeter carbon and oxygen isotope variations in the enamel of individual fossil horse teeth to assess ancient annual meteoric water variations and feeding patterns. The δ18O values from a 6.8 Ma fossil horse tooth (Astrohippus ansae) from Texas vary cyclically along the 6 cm length of the tooth with a smoothed amplitude of >4‰, similar to the monthly averaged amplitude measured in modern meteoric waters from the region. The seasonal δ18O values are ˜3‰ to 4‰ higher than those calculated from modern meteoric water data, suggesting either a higher local meteoric water value in the Miocene of Texas, or that the animal received a high proportion of its dietary water from plants or highly evaporated water. A Holocene horse tooth from the shores of Glacial Lake Agassiz, North Dakota (Equus sp.), also has isotopic variations with the same 35 mm periodicity, but a smoothed amplitude of only 2‰. This horse most likely had a buffered drinking supply. The calculated δ18O of the water in equilibrium with this tooth is the same as the modern measured annual average. The variations within a single tooth can be as large as those generally observed in entire stratigraphic sections of fossil teeth analyzed by bulk methods. The new method provides an important technique for evaluating fossil diagenesis; conventional bulk analyses of teeth fragments may not be representative of the whole tooth, thus explaining analytical scatter that has been previously attributed to diagenesis.

  13. Hydrogen Isotopes Record the History of the Martian Hydrosphere and Atmosphere

    Science.gov (United States)

    Usui, T.; Simon, J. I.; Jones, J. H.; Kurokawa, H.; Sato, M.; Alexander, C. M. O'D; Wang, J.

    2015-01-01

    The surface geology and geomorphology of Mars indicates that it was once warm enough to maintain a large body of liquid water on its surface, though such a warm environment might have been transient. The transition to the present cold and dry Mars is closely linked to the history of surface water, yet the evolution of surficial water is poorly constrained. This study presents insights from hydrogen isotopes for the origin and evolution of Martian water reservoirs.

  14. A new record of the Paleocene Carbon Isotope Maximum from the Mississippi Embayment

    Science.gov (United States)

    Platt, B. F.; Gerweck, E. D.

    2017-12-01

    The Paleocene-Eocene interval is well known as a time of climatic transitions, especially hyperthermals associated with disturbances in the carbon cycle that are used as proxies for impacts of projected anthropogenic global climate change. A recent roadcut in Benton County, Mississippi exposes a disconformity between the Paleocene Naheola Formation and the Eocene Meridian Sand. The disconformity is developed on a thick, kaolinitic paleosol, which we interpret as a mature Oxisol that supported tropical rainforest vegetation (as evidenced by associated well preserved leaf fossils). The nature of the paleosol at the disconformity led us to hypothesize that the strata might contain evidence of the Paleocene Eocene Thermal Maximum (PETM). We sampled two Mississippi Mineral Resources Institute (MMRI) cores from the equivalent stratigraphic interval from Benton and Tippah Counties, Mississippi, for bulk organic carbon stable isotopes at 25-cm intervals. Results showed no evidence of the negative excursion characteristic of the PETM. Instead, we found a gradual upsection enrichment that we interpret as the positive trend characteristic of the lower Paleocene Carbon Isotope Maximum (PCIM). This is reasonable based on published biostratigraphy and absolute ages from elsewhere in the Naheola Formation. Further analyses will be performed to determine whether the PCIM trend continues throughout the remainder of the core. The identification of the PCIM in Mississippi Embayment (ME) sediments is important because stable carbon isotope data may be useful for improving chronostratigraphy in the ME. Also, the PCIM is associated with a gradual warming trend as indicated by previously published stable oxygen isotopes from benthic foraminifera. Studying successive ME paleosols throughout the PCIM may yield information about the impacts of gradual atmospheric warming on soils and associated terrestrial systems.

  15. Contribution to the knowledge of pathogenic fungi of spiders in Argentina. Southernmost record in the world.

    Science.gov (United States)

    Manfrino, Romina G; González, Alda; Barneche, Jorge; Tornesello Galván, Julieta; Hywell-Jones, Nigel; López Lastra, Claudia C

    The aim of this study was to identify entomopathogenic fungi infecting spiders (Araneae) in a protected area of Buenos Aires province, Argentina. The Araneae species identified was Stenoterommata platensis. The pathogens identified were Lecanicillium aphanocladii Zare & W. Gams, Purpureocillium lilacinum (Thom) Luangsa-ard, Houbraken, Hywel Jones & Samson and Ophiocordyceps caloceroides (Berk & M.A. Curtis). This study constitutes the southernmost records in the world and contributes to expanding the knowledge of the biodiversity of pathogenic fungi of spiders in Argentina. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. An Ontology for Musical Phonographic Records: Contributing with a Representation Model

    Science.gov (United States)

    de Oliveira Albuquerque, Marcelo; Siqueira, Sean Wolfgand M.; de Saldanha da G. Lanzelotte, Rosana; Braz, Maria Helena L. B.

    Music is a complex domain with some interesting specificities that makes it difficult to be modeled. If different types of music are considered, then the difficulties are even bigger. This paper presents some of the characteristics that makes music such a hard domain to model and proposes an ontology for representing musical phonographic records. This ontology will provide a global representation that can be used to support systems interoperability and data integration, which provides disseminating music worldwide, contributing to culture in the knowledge society.

  17. Stable isotope records for the last 10 000 years from Okshola cave (Fauske, northern Norway and regional comparisons

    Directory of Open Access Journals (Sweden)

    H. Linge

    2009-11-01

    Full Text Available The sensitivity of terrestrial environments to past changes in heat transport is expected to be manifested in Holocene climate proxy records on millennial to seasonal timescales. Stalagmite formation in the Okshola cave near Fauske (northern Norway began at about 10.4 ka, soon after the valley was deglaciated. Past monitoring of the cave and surface has revealed stable modern conditions with uniform drip rates, relative humidity and temperature. Stable isotope records from two stalagmites provide time-series spanning from c. 10 380 yr to AD 1997; a banded, multi-coloured stalagmite (Oks82 was formed between 10 380 yr and 5050 yr, whereas a pristine, white stalagmite (FM3 covers the period from ~7500 yr to the present. The stable oxygen isotope18Oc, stable carbon isotope13Cc, and growth rate records are interpreted as showing i a negative correlation between cave/surface temperature and δ18Oc, ii a positive correlation between wetness and δ13Cc, and iii a positive correlation between temperature and growth rate. Following this, the data from Okshola show that the Holocene was characterised by high-variability climate in the early part, low-variability climate in the middle part, and high-variability climate and shifts between two distinct modes in the late part.

    A total of nine Scandinavian stalagmite δ18Oc records of comparable dating precision are now available for parts or most of the Holocene. None of them show a clear Holocene thermal optimum, suggesting that they are influenced by annual mean temperature (cave temperature rather than seasonal temperature. For the last 1000 years, δ18Oc values display a depletion-enrichment-depletion pattern commonly interpreted as reflecting the conventional view on climate development for the last millennium. Although the δ18

  18. Stable Isotopic signatures of Adélie penguin remains provide long-term paleodietary records in Northern Victoria Land (Ross Sea, Antarctica)

    Science.gov (United States)

    Lorenzini, Sandra; Baroni, Carlo; Fallick, Anthony Edward; Baneschi, Ilaria; Salvatore, Maria Cristina; Zanchetta, Giovanni; Dallai, Luigi

    2010-05-01

    The stable isotopes geochemistry of carbon and nitrogen provides a powerful tools for investigating in animal dietary patterns and shifts during the past. The signature of C and N isotopes provide direct information about the diet of an individual and its dietary patterns, especially when the dietary sources consist of prey from different trophic levels (i.e. different C and N isotopic composition) (DeNiro and Epstein 1978, Minawaga and Wada 1984, Koch et al. 1994, Hobson 1995). By analyzing the isotopic composition of penguin remains, we present a new detailed Adélie penguin (Pygoscelis adeliae) paleodietary record for the area of Terra Nova Bay (Victoria Land, Ross Sea). Adélie penguins primarily feed on fish (mainly the silverfish Pleuragramma antarcticum) and krill (Euphausia superba, Euphausia cristallorophias) (Ainley 2002, Lorenzini et al. 2009) that belonging to two different trophic levels. Consequently, they are characterized by different isotopic signatures. Specifically, we analyzed 13C/12C and 15N/14N ratios of more than one thousand of modern and fossil Adélie penguin eggshell and guano samples collected from ornithogenic soils (penguin guano-formed) dated back to ≈7,200 years BP (Baroni and Orombelli 1994, Lambert et al. 2002, Baroni and Hall 2004, Hall et al. 2006). The expanded database of stable isotope values obtained from Adélie penguin remains define a detailed paleodietary record with an excellent temporal continuity over all the investigated time period. Our data indicate a significant dietary shift between fish and krill, with a gradual decrease from past to present time in the proportion of fish compared to krill in Adélie penguin diet. From 7200 yrs BP to 2000 yrs BP, δ13C and δ15N values indicate fish as the most eaten prey. The dietary contribution of lower-trophic prey in penguin diet started becoming evident not earlier than 2000 yrs BP, when the δ13C values reveal a mixed diet based on fish and krill consumption. Modern

  19. Carbon isotopic record from Upper Devonian carbonates at Dongcun in Guilin, southern China, supporting the world-wide pattern of carbon isotope excursions during Frasnian-Famennian transition

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Two positive δ13C excursions are presented in records from the Frasnian-Famennian (F-F) marine carbonate sediments in Europe, America, Africa, and Australia, having been considered as a worldwide pattern, and attributed to enhanced organic carbon burial during the F-F biological mass extinction. However, this worldwide pattern has not been revealed from the well-deposited Late Devonian sequences in southern China. In this paper, a detailed investigation has been made on the Late Devonian section at Dongcun, Guilin, southern China to constrain perturbations in δ13C of carbonates in the F-F deposited sequence. The result from this section also indicates two positive δ13C excursions during the F-F transition. The first excursion with an amplitude of 1.5‰ occurred at the bottom of linguiformis Zone, later than the early excursion existing in the Late rhenana Zone of the Late Devonian profiles in other continents, especially, in central Europe. This difference has been expected to be a result as conodont Palmatolepis linguiformis occurred earlier in southern China than other sites. The second excursion with an amplitude of 2.1‰ is located at the F-F boundary, same as the records from other continents. This result strongly supports the view that two carbon isotope positive excursions during the F-F transition are common in carbonate sediments, resulting from worldwide increases of organic carbon burial intensity.

  20. Hydrogen Isotopic Composition of Apatite in Northwest Africa 7034: A Record of the "Intermediate" H-Isotopic Reservoir in the Martian Crust?

    Science.gov (United States)

    McCubbin, F. M.; Barnes, J. J.; Santos, A. R.; Boyce, J. W.; Anand, M.; Franchi, I. A.; Agee, C. B.

    2016-01-01

    Northwest Africa (NWA) 7034 and its pairings comprise a regolith breccia with a basaltic bulk composition [1] that yields a better match than any other martian meteorite to visible-infrared reflectance spectra of the martian surface measured from orbit [2]. The composition of the fine-grained matrix within NWA 7034 bears a striking resemblance to the major element composition estimated for the martian crust, with several exceptions. The NWA 7034 matrix is depleted in Fe, Ti, and Cr and enriched in Al, Na, and P [3]. The differences in Al and Fe are the most substantial, but the Fe content of NWA 7034 matrix falls within the range reported for the southern highlands crust [6]. It was previously suggested by [4] that NWA 7034 was sourced from the southern highlands based on the ancient 4.4 Ga ages recorded in NWA 7034/7533 zircons [4, 5]. In addition, the NWA 7034 matrix material is enriched in incompatible trace elements by a factor of 1.2-1.5 [7] relative to estimates of the bulk martian crust. The La/Yb ratio of the bulk martian crust is estimated to be approximately 3 [7], and the La/Yb of the NWA 7034 matrix materials ranges from approximately 3.9 to 4.4 [3, 8], indicating a higher degree of LREE enrichment in the NWA 7034 matrix materials. This elevated La/Yb ratio and enrichment in incompatible lithophile trace elements is consistent with NWA 7034 representing a more geochemically enriched crustal terrain than is represented by the bulk martian crust, which would be expected if NWA 7034 represents the bulk crust from the southern highlands. Given the similarities between NWA 7034 and the martian crust, NWA 7034 may represent an important sample for constraining the composition of the martian crust, particularly the ancient highlands. In the present study, we seek to constrain the H isotopic composition of the martian crust using Cl-rich apatite in NWA 7034. Usui et al., [9] recently proposed that a H isotopic reservoir exists within the martian crust that has

  1. Contribution of isotopic and geochemical tracers to the administration of water resources: the strontium case

    International Nuclear Information System (INIS)

    Verdoux, P.; Lancelot, J.; Faillat, J.P.

    1995-01-01

    A better understanding of groundwater origin(s) and a quantitative and qualitative evaluation of exploited resources is a preliminary condition for rational administration and preventive actions. The determination of Sr contents and isotopic compositions associated or not to other elements is a new method applied in underground domains which has proven to be effective for example in Languedoc-Rousillon, particularly in areas where classical natural and even artificial tracers are unreliable. The use of 87 Sr/ 86 Sr tracer is based on the condition that each analysed rock-system is defined by a typical isotopic composition. In the Cevennes and Lozere, sedimentary carbonate rocks display 87 Sr/ 86 Sr ratios ranging from 0.707 to 0.709, similar to those of seawater,while silicate rocks exhibit values from 0.710 to 0.750, depending on Rb/Sr ratios, ages and resistance of the different minerals to weathering processes. Sr data obtained in the Lozere suggest important binary mixing of water between an homogeneous end member representing the composition of water flowing on the crystalline basement and a second component corresponding to water from karstic springs and to captive waters of the lower aquifer reached at 200 m in depth by borehole. Calculated mixing curves between the basement and the karstic water end members would allow to define the nature and volumetric importance of storage and to evaluate pollution risks. (J.S.). 17 refs., 9 figs., 3 tabs

  2. STRONTIUM ISOTOPE STRATIGRAPHY AS A CONTRIBUTION FOR DATING MIOCENE SHELF CARBONATES (S. MARINO FM., NORTHERN APENNINES

    Directory of Open Access Journals (Sweden)

    CLAUDIO ARGENTINO

    2017-01-01

    Full Text Available This paper provides new data on strontium isotope stratigraphy applied to the Miocene heterozoan shelfal carbonates of the S. Marino Fm. (Marecchia Valley, northern Apennines. Sr isotopic analyses were carried out on oyster shells, bryozoans and bulk-rocks from the lower-middle carbonate portion of the section. In the upper part of the succession that shows evidence of detrital influx,87Sr/86Sr analyses were performed on foraminifera tests, separating planktonic and benthic forms. Results were compared with calcareous nannofossil biostratigraphic data from the same levels, in order to test the reliability of Sr dating in mixed carbonate-siliciclastic sediments. Mean ages obtained from oysters range between 16.9 Ma and 16.3 Ma. Very similar results are obtained using bryozoans (16.5 Ma to 16.1 Ma and bulk-rocks (16.8 Ma to 16.2 Ma. These results allow to better constrain the age of the massive carbonate shelf, referable to the upper Burdigalian. In the upper carbonate-siliciclastic portion of the shelf, numerical ages obtained from planktonic and benthic foraminifera are in good agreement with nannofossil biozones (mean ages respectively around 15.3 Ma and 14.5 Ma although they display wide confidence intervals. These wide age uncertainties depend on the slow rate of change of marine 87Sr/86Sr through time that characterizes the interval between ~15 and ~13.5 Ma.

  3. Contribution of environmental isotopes to the study of large aquifers in Morocco

    International Nuclear Information System (INIS)

    Kabbaj, A.; Zeryouhi, I.; Carlier, P.

    1978-01-01

    The geochemistry of environmental isotopes has been applied to several aquifers in Maroc, some of them quite large: Charf el Akab in the Tanger region, the Oum er Rbia basin and the Tadla aquifer, the free nappe of limnic limes tone in the Sais plane, and the lias limestone aquifer. The isotopic investigations on the basis of hydrogeochemical data have given more precise information on the supply conditions of these aquifers. The types of water of different origin from the Atlas or the phosphate plateau in the Sais plane and the Tadla basin have been distinguished, the supply from one aquifer to another Lias nappe which, via the flexures of the Sais plane, supplies the nappe of limic limestone has been assessed, the homogeneity or heterogeneity of these aquifers has been investigated as well as their impermeability, the Tadla aquifer and the special case of Charf el Akab compared with the marine region. The findings have proved the usefulness of these techniques and permitted a specification of the general conditions for their application. (orig.) [de

  4. The contribution of environmental isotopes to studies of large aquifers in Morocco

    International Nuclear Information System (INIS)

    Kabbaj, A.; Zeryouhi, I.; Carlier, Ph.

    1979-01-01

    The geochemistry of environmental isotopes has been used for the study of various aquifers in Morocco, some of which are large, such as the Charf el Akab in the Tangiers area, the Oum er Rbia basin and the Turonian aquifer of the Tadla, the free groundwater of the Quaternary lacustrine limestones of the Sais Plain and the Lias limestone aquifer. These isotope studies take hydrogeochemical data into account and have made it possible to determine the conditions of recharge of the aquifers, to distinguish waters of different origin from the Atlas Mountains or from the Phosphate Plateau in the Tadla Basin and the Sais plain, to estimate the recharge of one aquifer by another - for example groundwater of the Lias limestones passing via the folds of the Sais Plain into the lacustrine limestone aquifer - and to test the homogeneity or heterogeneity of these aquifers and their tightness (e.g. the Turonian aquifer of the Tadla and the special case of the Charf el Akab in relation to the marine environment). Altogether, these results made it possible to test the value of the techniques used and to specify the general conditions in which they can profitably be used. (author)

  5. EVALUATION OF GLACIER MELT CONTRIBUTION TO RUNOFF IN THE NORTH CAUCASUS ALPINE CATCHMENTS USING ISOTOPIC METHODS AND ENERGY BALANCE MODELING

    Directory of Open Access Journals (Sweden)

    E. Rets

    2017-01-01

    Full Text Available Frequency and intensity of river floods rise observed in the North Caucasus during last decades is considered to be driven by recent climate change. In order to predict possible future trends in extreme hydrological events in the context of climate change, it is essential to estimate the contribution of different feed sources in complicated flow-forming processes in the alpine part of the North Caucasus. A study was carried out for the Djankuat River basin, the representative for the North Caucasus system. Simultaneous measurements of electrical conductivity, isotopic and ion balance equations, and energy balance modeling of ice and snow melt were used to evaluate the contribution of different sources and processes in the Djankuat River runoff regime formation. A forecast of possible future changes in the Djankuat glacier melting regime according to the predicted climate changes was done.

  6. Isotopic Evidence of a Wide Spectrum of Feeding Strategies in Southern Hemisphere Humpback Whale Baleen Records.

    Science.gov (United States)

    Eisenmann, Pascale; Fry, Brian; Holyoake, Carly; Coughran, Douglas; Nicol, Steve; Bengtson Nash, Susan

    2016-01-01

    Our current understanding of Southern hemisphere humpback whale (Megaptera novaeangliae) ecology assumes high-fidelity feeding on Antarctic krill in Antarctic waters during summer, followed by fasting during their annual migration to and from equatorial breeding grounds. An increase in the number of reported departures from this feeding/fasting model suggests that the current model may be oversimplified or, alternatively, undergoing contemporary change. Information about the feeding and fasting cycles of the two Australian breeding populations of humpback whales were obtained through stable isotope analysis of baleen plates from stranded adult individuals. Comparison of isotope profiles showed that individuals from the West Australian breeding population strongly adhered to the classical feeding model. By contrast, East Australian population individuals demonstrated greater heterogeneity in their feeding. On a spectrum from exclusive Antarctic feeding to exclusive feeding in temperate waters, three different strategies were assigned and discussed: classical feeders, supplemental feeders, and temperate zone feeders. Diversity in the inter-annual feeding strategies of humpback whales demonstrates the feeding plasticity of the species, but could also be indicative of changing dynamics within the Antarctic sea-ice ecosystem. This study presents the first investigation of trophodynamics in Southern hemisphere humpback whales derived from baleen plates, and further provides the first estimates of baleen plate elongation rates in the species.

  7. Isotopic Evidence of a Wide Spectrum of Feeding Strategies in Southern Hemisphere Humpback Whale Baleen Records.

    Directory of Open Access Journals (Sweden)

    Pascale Eisenmann

    Full Text Available Our current understanding of Southern hemisphere humpback whale (Megaptera novaeangliae ecology assumes high-fidelity feeding on Antarctic krill in Antarctic waters during summer, followed by fasting during their annual migration to and from equatorial breeding grounds. An increase in the number of reported departures from this feeding/fasting model suggests that the current model may be oversimplified or, alternatively, undergoing contemporary change. Information about the feeding and fasting cycles of the two Australian breeding populations of humpback whales were obtained through stable isotope analysis of baleen plates from stranded adult individuals. Comparison of isotope profiles showed that individuals from the West Australian breeding population strongly adhered to the classical feeding model. By contrast, East Australian population individuals demonstrated greater heterogeneity in their feeding. On a spectrum from exclusive Antarctic feeding to exclusive feeding in temperate waters, three different strategies were assigned and discussed: classical feeders, supplemental feeders, and temperate zone feeders. Diversity in the inter-annual feeding strategies of humpback whales demonstrates the feeding plasticity of the species, but could also be indicative of changing dynamics within the Antarctic sea-ice ecosystem. This study presents the first investigation of trophodynamics in Southern hemisphere humpback whales derived from baleen plates, and further provides the first estimates of baleen plate elongation rates in the species.

  8. Scale and the isotopic record of C4 plants in pedogenic carbonate: from the biome to the rhizospere.

    Energy Technology Data Exchange (ETDEWEB)

    Monger, Dr. H Curtis [New Mexico State University, Las Cruces; Cole, David R [ORNL; Buck, Dr. Brenda [University of Nevada, Las Vegas; Gallegos, Robert [Sant fe Water Division

    2009-01-01

    The 13C/12C ratio in pedogenic carbonate (i.e., CaCO3 formed in soil) is a significant tool for investigating C4 biomes of the past. However, the paleoecological meaning of d13C values in pedogenic carbonate can change with the scale at which one considers the data. We describe studies of modern soils, fossil soils, and vegetation change in the Chihuahuan Desert of North America and elsewhere that reveal four scales important for paleoecologic interpretations. (1) At the broadest scale, the biome scale (hundreds to millions of km2), an isotopic record interpreted as C3 vegetation replacing C4 grasslands may indicate invading C3 woody shrubs instead of expanding C3 forests (a common interpretation). (2) At the landscape scale (several tens of m2 to hundreds of km2), the accuracy of scaling up paleoclimatic interpretations to a regional level is affected by the landform containing the isotopic record. (3) At the soil-profile scale (cm2 to m2), soil profiles with multiple generations of carbonate mixed together have a lower-resolution paleoecologic record than soil profiles repeatedly buried. (4) At the rhizosphere scale (lm2 to cm2), carbonate formed on roots lack the 14 17 enrichment observed at broader scales, revealing different fractionation processes at different scales. A multi-scale approach in dealing with d13C in pedogenic carbonate will increase the accuracy of paleoecologic interpretations and understanding of soil geomorphic climatic interactions that affect boundaries between C4 and C3 vegetation.

  9. Scale and the isotopic record of C4 plants in pedogenic carbonate: from the biome to the rhizosphere

    Energy Technology Data Exchange (ETDEWEB)

    Monger, Dr. H Curtis [New Mexico State University, Las Cruces; Cole, David [Ohio State University; Buck, Dr. Brenda [University of Nevada, Las Vegas; Gallegos, Robert [Sant fe Water Division

    2009-01-01

    The 13C/12C ratio in pedogenic carbonate (i.e., CaCO3 formed in soil) is a significant tool for investigating C4 biomes of the past. However, the paleoecological meaning of d13C values in pedogenic carbonate can change with the scale at which one considers the data. We describe studies of modern soils, fossil soils, and vegetation change in the Chihuahuan Desert of North America and elsewhere that reveal four scales important for paleoecologic interpretations. (1) At the broadest scale, the biome scale (hundreds to millions of km2), an isotopic record interpreted as C3 vegetation replacing C4 grasslands may indicate invading C3 woody shrubs instead of expanding C3 forests (a common interpretation). (2) At the landscape scale (several tens of m2 to hundreds of km2), the accuracy of scaling up paleoclimatic interpretations to a regional level is affected by the landform containing the isotopic record. (3) At the soil-profile scale (cm2 to m2), soil profiles with multiple generations of carbonate mixed together have a lower-resolution paleoecologic record than soil profiles repeatedly buried. (4) At the rhizosphere scale (lm2 to cm2), carbonate formed on roots lack the 14 17 enrichment observed at broader scales, revealing different fractionation processes at different scales. A multi-scale approach in dealing with d13C in pedogenic carbonate will increase the accuracy of paleoecologic interpretations and understanding of soil geomorphic climatic interactions that affect boundaries between C4 and C3 vegetation.

  10. Molecular and Isotopic Records of Combustion Inputs to the Environment Over the Last 250 Years

    National Research Council Canada - National Science Library

    DeLima, Ana

    2004-01-01

    .... This study generated a high-resolution historical record of pyrogenic PAR emissions since pre-industrial times from anoxic aquatic sediments, allowing for detailed comparison with energy consumption data...

  11. Contribution to the study of evaporation of natural water using stable isotope

    International Nuclear Information System (INIS)

    Takaki, T.

    1979-01-01

    Procedures for measurements of isotopic ratios in natural waters have been developed, in order to study evaporation mechanism in reservoirs, in laboratory scale. Rayleigh's model of evaporation is discussed, considering evaporation in the presence of atmospheric water vapor. The results obtained for the variation of the concentration of O 18 and D, in function of remaining water fraction for four evaporation reservoirs agree with the model presented and allow an estimation of the local average relative humidity. The straight-line equation that relates the results for the concentrations of O 18 and D in our samples is proper to water reservoirs subjected to a significant reduction in its volume by evaporation. The content of O 18 and D, in water prior the evaporation directly obtained from the intersection, of the meteoric with our line agree with the values measured for the water used to fill the reservoirs [pt

  12. Contribution to the isotopic analysis of nitrogen using optical spectrometry; Contribution a l'analyse isotopique de l'azote par spectrometrie optique

    Energy Technology Data Exchange (ETDEWEB)

    Leicknam, J P [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    The possibility of analyzing a gaseous mixture of {sup 14}N{sub 2} and {sup 14}N-{sup 15}N by emission spectrometry is well known. However, for mixtures which are poor in nitrogen 15 (isotopic abundance less than 2 per cent), the methods proposed up till now do not give sufficiently accurate results rapidly. The method of isotopic analysis proposed here only requires a spectrometer of average resolving power; it is even possible, as we have done; to use a spectrograph with a slit replacing the photographic plate, and a photomultiplier; this transformation is very simple to carry out and the signals from the detector can then be received by a recorder. Under these conditions a measurement takes only from three to ten minutes, according to the accuracy required. The light sources are made up of electrode-less discharge lamps, excited by high frequency; the filling conditions are such that the lamps may be prepared in a few minutes, the impurities being sufficiently eliminated for the measurements not to be affected. The choice of the analytical band couple depends on the relative position of the isotopic bands and on the possible presence of traces of these impurities: amongst the transitions in the system C({sup 3}{pi}{sub u}) <-> B({sup 3}{pi}{sub g}), it is the 2 {yields} 0 transition which has the most favorable position for this isotopic analysis. The method is applied to samples of varying origins (ammonium salts, fertilizer and plants): the isotopic contents are determined with an accuracy of 3 per cent in the neighbourhood of the natural abundance, and of 1 per cent when the sample contains about 1.5 atoms of nitrogen-15 for 100 atoms of nitrogen-14. The accuracy is therefore quite sufficient for most of the biological research using the mass 15 as tracer. (author) [French] La possibilite d'analyser un melange gazeux des azotes {sup 14}N{sub 2} et {sup 14}N-{sup 15}N par spectrometrie d'emission est bien connue. Cependant, pour des melanges pauvres en azote

  13. Hydrothermal sediments as a potential record of seawater Nd isotope compositions: The Rainbow vent site (36°14'N, Mid-Atlantic Ridge)

    Science.gov (United States)

    Chavagnac, ValéRie; Palmer, Martin R.; Milton, J. Andrew; Green, Darryl R. H.; German, Christopher R.

    2006-09-01

    Geochemical compositions and Sr and Nd isotopes were measured in two cores collected ˜2 and 5 km from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge. Overall, the cores record enrichments in Fe and other metals from hydrothermal fallout, but sequential dissolution of the sediments allows discrimination between a leach phase (easily leachable) and a residue phase (refractory). The oxy-anion and transition metal distribution combined with rare earth element (REE) patterns suggest that (1) the leach fraction is a mixture of biogenic carbonate and hydrothermal Fe-Mn oxy-hydroxide with no significant contribution from detrital material and (2) >99.5% of the REE content of the leach fraction is of seawater origin. In addition, the leach fraction has an average 87Sr/86Sr ratio indistinguishable from modern seawater at 0.70916. Although we lack the ɛNd value of present-day deep water at the Rainbow vent site, we believe that the REE budget of the leach fraction is predominantly of seawater origin. We suggest therefore that the leach fraction provides a record of local seawater ɛNd values. Nd isotope data from these cores span the period of 4-14 ka (14C ages) and yield ɛNd values for North East Atlantic Deep Water (NEADW) that are higher (-9.3 to -11.1) than those observed in the nearby Madeira Abyssal Plain from the same depth (-12.4 ± 0.9). This observation suggests that either the Iceland-Scotland Overflow Water (ISOW) and Lower Deep Water contributions to the formation of NEADW are higher along the Mid-Atlantic Ridge than in the surrounding basins or that the relative proportion of ISOW was higher during this period than is observed today. This study indicates that hydrothermal sediments have the potential to provide a higher-resolution record of deep water ɛNd values, and hence deepwater circulation patterns in the oceans, than is possible from other types of sediments.

  14. Compound-specific isotope records of late-quaternary environmental change in southeastern North Carolina

    Science.gov (United States)

    Lane, Chad S.; Taylor, Audrey K.; Spencer, Jessica; Jones, Kaylee B.

    2018-02-01

    Reconstructions of late Quaternary paleohydrology are rare from the U.S. Atlantic coastal plain (ACP). Here we present compound-specific hydrogen (δ2Halkane) and carbon (δ13Calkane) isotope analyses of terrestrially-derived n-alkanes from Jones Lake and Singletary Lake in eastern North Carolina spanning the last ∼50,000 years. Combined with pollen, charcoal, and bulk geochemical analyses, the δ2Halkane data indicate arid conditions during the late-Pleistocene, but differing edaphic conditions at the sites perhaps related to differing water table depths. The δ13Calkane data indicate a significant C4 plant component during the late Pleistocene, but other proxies indicate a sparsely-vegetated landscape. The Pleistocene-Holocene transition is marked by rapid fluctuations in δ2Halkane values that are similar to the patterns of Bølling Allerød and Younger Dryas isotope data from Greenland indicating sensitivity of the regional climate to short-lived, high-amplitude climatic events. The δ2Halkane data indicate a mesic early Holocene that supported colonization by Quercus-dominated ecosystems. Evidence of middle Holocene aridity in eastern Tennessee and western North Carolina contrasts with evidence of mesic conditions on the ACP, a geographic pattern similar to modern teleconnected precipitation responses to the Pacific Decadal Oscillation. A transition to Pinus-dominated ecosystems ∼5500 cal yr B.P. is accompanied by a large increase charcoal, but is not coincident with any large changes in δ2Halkane values, indicating that hydrologic change was likely not responsible for sustained late-Holocene dominance of Pinus. The lack of a change in middle Holocene hydrology and the spatiotemporally heterogeneous nature of the Quercus-Pinus transition on the ACP indicate prehistoric anthropogenic land management practices may represent the most parsimonious explanation for the regionally pervasive ecological change.

  15. Atmospheric methane isotopic record favors fossil sources flat in 1980s and 1990s with recent increase

    Science.gov (United States)

    Rice, Andrew L.; Butenhoff, Christopher L.; Teama, Doaa G.; Röger, Florian H.; Khalil, M. Aslam K.; Rasmussen, Reinhold A.

    2016-09-01

    Observations of atmospheric methane (CH4) since the late 1970s and measurements of CH4 trapped in ice and snow reveal a meteoric rise in concentration during much of the twentieth century. Since 1750, levels of atmospheric CH4 have more than doubled to current globally averaged concentration near 1,800 ppb. During the late 1980s and 1990s, the CH4 growth rate slowed substantially and was near or at zero between 1999 and 2006. There is no scientific consensus on the drivers of this slowdown. Here, we report measurements of the stable isotopic composition of atmospheric CH4 (13C/12C and D/H) from a rare air archive dating from 1977 to 1998. Together with more modern records of isotopic atmospheric CH4, we performed a time-dependent retrieval of methane fluxes spanning 25 y (1984-2009) using a 3D chemical transport model. This inversion results in a 24 [18, 27] Tg y-1 CH4 increase in fugitive fossil fuel emissions since 1984 with most of this growth occurring after year 2000. This result is consistent with some bottom-up emissions inventories but not with recent estimates based on atmospheric ethane. In fact, when forced with decreasing emissions from fossil fuel sources our inversion estimates unreasonably high emissions in other sources. Further, the inversion estimates a decrease in biomass-burning emissions that could explain falling ethane abundance. A range of sensitivity tests suggests that these results are robust.

  16. Oxygen Isotope Speleothem record of Decadal and Multidecadal Atlantic Oscillations over the last millennium in Southwestern Morocco

    Science.gov (United States)

    Ait Brahim, Yassine; Sha, LiJuan; Sifeddine, Abdelfettah; Cheng, Hai; Bouchaou, Lhoussaine; Da Cruz Junior, Francisco William; Khodri, Myriam; Peerbocus, Nawaaz; Mariller, Alexandre; Apaestegui, James; Guyot, Jean-Loup; Auler, Augusto; Hassane Beraaouz, El

    2016-04-01

    In this work, we present a stable oxygen isotope (δ18O) speleothem record from Ifoulki cave located South-West of Morocco (N 30°42'29'', W 09°19'39'' and 1267 meters above sea level). The age model, based on eighteen U-Th dates, reveals that the record covers the AD 790-1953 period with a data resolution of ~1.7 years. Stable oxygen isotope variations show substantial decadal to multi-decadal swings between dry and humid periods. The Medieval Climate Anomaly (MCA) is characterized by the longest period with δ18O values above the average, suggestive of pronounced drying possibly as a response to positive North Atlantic Oscillation (NAO) phases and increased volcanic activity during this period. However, at least two short wet phases are recognized during the MCA in Morocco, with peaks centered on the years AD 1040 and AD 1190 and seem to overlap with negative NAO phases as recorded in a recently published NAO reconstruction for the last millennium. During the next centuries, the NAO again depicts predominantly negative values and the δ18O drops below the average during the Little Ice Age (LIA). Furthermore, a striking resemblance is observed between our record and another recently published stalagmite record from the Piste cave in Northeastern Morocco, which is quite remarkable given the different type of tracers (δ18O vs. Mg and Sr) obtained from different environments (Western High Atlas vs. Northeastern Middle Atlas and ~634 km away). Comparison with regional paleorecords from other studies also reveals the replication of many characteristic climate features from the last millennium, first detected in Northern Morocco and the Iberian Peninsula. In particular, the evidence of generally dry conditions during the MCA and wetter conditions in the LIA, which is confirmed by all the paleorecords. These similarities indicate coherent climate variability in Northwest Africa and the Iberian Peninsula and suggest a strong regional control of the NAO during the last

  17. Could a secular increase in organic burial explain the rise of oxygen? Insights from a geological carbon cycle model constrained by the carbon isotope record

    Science.gov (United States)

    Krissansen-Totton, J.; Kipp, M.; Catling, D. C.

    2017-12-01

    The stable isotopes of carbon in marine sedimentary rock provide a window into the evolution of the Earth system. Conventionally, a relatively constant carbon isotope ratio in marine sedimentary rocks has been interpreted as implying constant organic carbon burial relative to total carbon burial. Because organic carbon burial corresponds to net oxygen production from photosynthesis, it follows that secular changes in the oxygen source flux cannot explain the dramatic rise of oxygen over Earth history. Instead, secular declines in oxygen sink fluxes are often invoked as causes for the rise of oxygen. However, constant fractional organic burial is difficult to reconcile with tentative evidence for low phosphate concentrations in the Archean ocean, which would imply lower marine productivity and—all else being equal—less organic carbon burial than today. The conventional interpretation of the carbon isotope record rests on the untested assumption that the isotopic ratio of carbon inputs into the ocean reflect mantle isotopic values throughout Earth history. In practice, differing rates of carbonate and organic weathering will allow for changes in isotopic inputs, as suggested by [1] and [2]. However, these inputs can not vary freely because large changes in isotopic inputs would induce secular trends in carbon reservoirs, which are not observed in the isotope record. We apply a geological carbon cycle model to all Earth history, tracking carbon isotopes in crustal, mantle, and ocean reservoirs. Our model is constrained by the carbon isotope record such that we can determine the extent to which large changes in organic burial are permitted. We find both constant organic burial and 3-5 fold increases in organic burial since 4.0 Ga can be reconciled with the carbon isotope record. Changes in the oxygen source flux thus need to be reconsidered as a possible contributor to Earth's oxygenation. [1] L. A. Derry, Organic carbon cycling and the lithosphere, in Treatise on

  18. Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

    Science.gov (United States)

    Odigie, Kingsley; Cohen, A.D.; Swarzenski, Peter W.; Flegal, R

    2014-01-01

    Lead isotopic and trace element records of two contrasting sediment cores were examined to reconstruct historic, industrial contaminant inputs to Lake Tanganyika, Africa. Observed fluxes of Co, Cu, Mn, Ni, Pb, and Zn in age-dated sediments collected from the lake varied both spatially and temporally over the past two to four centuries. The fluxes of trace elements were lower (up to 10-fold) at a mid-lake site (MC1) than at a nearshore site (LT-98-58), which is directly downstream from the Kahama and Nyasanga River watersheds and adjacent to the relatively pristine Gombe Stream National Park. Trace element fluxes at that nearshore site did not measurably change over the last two centuries (1815–1998), while the distal, mid-lake site exhibited substantial changes in the fluxes of trace elements – likely caused by changes in land use – over that period. For example, the flux of Pb increased by ∼300% from 1871 to 1991. That apparent accelerated weathering and detrital mobilization of lithogenic trace elements was further evidenced by (i) positive correlations (r = 0.77–0.99, p factors (EF operations within the lake’s watershed over the past century. The data also indicate that the mid-lake site is a much more sensitive and useful recorder of environmental changes than the nearshore site. Furthermore, the lead isotopic compositions of sediment at the sites differed spatially, indicating that the Pb (and other trace elements by association) originated from different natural sources at the two locations.

  19. Temporal record of Pu isotopes in inter-tidal sediments from the northeastern Irish Sea

    Energy Technology Data Exchange (ETDEWEB)

    Lindahl, Patric, E-mail: patriclindahl@yahoo.com [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Worsfold, Paul; Keith-Roach, Miranda [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Andersen, Morten B. [Bristol Isotope Group, School of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1RJ (United Kingdom); Kershaw, Peter; Leonard, Kins [The Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory, Pakefield Road, Suffolk NR33 0HT (United Kingdom); Choi, Min-Seok [Division of Earth and Environmental Science, Korea Basic Science Institute, 113 Gwahangno, Yusung-gu, Daejon 305-333 (Korea, Republic of); Boust, Dominique [Laboratoire de Radioecologie, Institut de Radioprotection et de Surete Nucleaire, BP 10, 50130 Cherbourg-Octeville (France); Lesueur, Patrick [University of Caen Basse Normandie, M2C UMR CNRS 6143, 14000 Caen (France)

    2011-11-01

    A depth profile of {sup 239}Pu and {sup 240}Pu specific activities and isotope ratios was determined in an inter-tidal sediment core from the Esk Estuary in the northeastern Irish Sea. The study site has been impacted with plutonium through routine radionuclide discharges from the Sellafield nuclear reprocessing plant in Cumbria, NW England. A pronounced sub-surface maximum of {approx} 10 kBq kg{sup -1} was observed for {sup 239+240}Pu, corresponding to the peak in Pu discharge from Sellafield in 1973, with a decreasing trend with depth down to {approx} 0.04 kBq kg{sup -1} in the deeper layers. The depth profile of {sup 239+240}Pu specific activities together with results from gamma-ray spectrometry for {sup 137}Cs and {sup 241}Am was compared with reported releases from the Sellafield plant in order to estimate a reliable sediment chronology. The upper layers (1992 onwards) showed higher {sup 239+240}Pu specific activities than would be expected from the direct input of annual Sellafield discharges, indicating that the main input of Pu is from the time-integrated contaminated mud patch of the northeastern Irish Sea. The {sup 240}Pu/{sup 239}Pu atom ratios ranged from {approx} 0.03 in the deepest layers to > 0.20 in the sub-surface layers with an activity-weighted average of 0.181. The decreasing {sup 240}Pu/{sup 239}Pu atom ratio with depth reflects the changing nature of operations at the Sellafield plant from weapons-grade Pu production to reprocessing spent nuclear fuel with higher burn-up times in the late 1950s. In addition, recent annual {sup 240}Pu/{sup 239}Pu atom ratios in winkles collected during 2003-2008 from three stations along the Cumbrian coastline showed no significant spatial or temporal differences with an overall average of 0.204, which supports the hypothesis of diluted Pu input from the contaminated mud patch. - Highlights: {yields} Depth profiles of {sup 239}Pu and {sup 240}Pu determined in a northeastern Irish Sea sediment. {yields

  20. Contributions of each isotope in structural material on radiation damage in a hybrid reactor

    International Nuclear Information System (INIS)

    Günay, Mehtap

    2016-01-01

    In this study, the fluids were used in the liquid first-wall, blanket and shield zones of the designed hybrid reactor system. In this study, salt-heavy metal mixtures consisting of 93–85% Li_2_0Sn_8_0 + 5% SFG-PuO_2 and 2-10% UO_2, 93–85% Li_2_0Sn_8_0 + 5% SFG-PuO_2 and 2-10% NpO_2, and 93–85% Li_2_0Sn_8_0 + 5% SFG-PuO_2 and 2-10% UCO were used as fluids. In this study, the effect on the radiation damage of spent fuel-grade (SFG)-PuO_2, UO_2, NpO_2 and UCO contents was investigated in the structural material of a designed fusion–fission hybrid reactor system. In the designed hybrid reactor system were investigated the effect on the radiation damage of the selected fluid according to each isotopes of structural material in the structural material for 30 full power years (FPYs). Three-dimensional analyses were performed using the most recent MCNPX-2.7.0 Monte Carlo radiation transport code and the ENDF/B-VII.0 nuclear data library

  1. Estimates of water source contributions in a dynamic urban water supply system inferred via a Bayesian stable isotope mixing model

    Science.gov (United States)

    Jameel, M. Y.; Brewer, S.; Fiorella, R.; Tipple, B. J.; Bowen, G. J.; Terry, S.

    2017-12-01

    Public water supply systems (PWSS) are complex distribution systems and critical infrastructure, making them vulnerable to physical disruption and contamination. Exploring the susceptibility of PWSS to such perturbations requires detailed knowledge of the supply system structure and operation. Although the physical structure of supply systems (i.e., pipeline connection) is usually well documented for developed cities, the actual flow patterns of water in these systems are typically unknown or estimated based on hydrodynamic models with limited observational validation. Here, we present a novel method for mapping the flow structure of water in a large, complex PWSS, building upon recent work highlighting the potential of stable isotopes of water (SIW) to document water management practices within complex PWSS. We sampled a major water distribution system of the Salt Lake Valley, Utah, measuring SIW of water sources, treatment facilities, and numerous sites within in the supply system. We then developed a hierarchical Bayesian (HB) isotope mixing model to quantify the proportion of water supplied by different sources at sites within the supply system. Known production volumes and spatial distance effects were used to define the prior probabilities for each source; however, we did not include other physical information about the supply system. Our results were in general agreement with those obtained by hydrodynamic models and provide quantitative estimates of contributions of different water sources to a given site along with robust estimates of uncertainty. Secondary properties of the supply system, such as regions of "static" and "dynamic" source (e.g., regions supplied dominantly by one source vs. those experiencing active mixing between multiple sources), can be inferred from the results. The isotope-based HB isotope mixing model offers a new investigative technique for analyzing PWSS and documenting aspects of supply system structure and operation that are

  2. Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Benech, H

    1999-05-28

    The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

  3. Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Benech, H

    1999-05-28

    The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

  4. The Juvenile Hafnium Isotope Signal as a Record of Supercontinent Cycles

    Science.gov (United States)

    Gardiner, Nicholas J.; Kirkland, Christopher L.; van Kranendonk, Martin J.

    2016-12-01

    Hf isotope ratios measured in igneous zircon are controlled by magmatic source, which may be linked to tectonic setting. Over the 200-500 Myr periodicity of the supercontinent cycle - the principal geological phenomenon controlling prevailing global tectonic style - juvenile Hf signals, i.e. most radiogenic, are typically measured in zircon from granites formed in arc settings (crustal growth), and evolved zircon Hf signals in granites formed in continent-collision settings (crustal reworking). Interrogations of Hf datasets for excursions related to Earth events commonly use the median value, however this may be equivocal due to magma mixing. The most juvenile part of the Hf signal is less influenced by crustal in-mixing, and arguably a more sensitive archive of Earth’s geodynamic state. We analyze the global Hf dataset for this juvenile signal, statistically correlating supercontinent amalgamation intervals with evolved Hf episodes, and breakup leading to re-assembly with juvenile Hf episodes. The juvenile Hf signal is more sensitive to Pangaea and Rodinia assembly, its amplitude increasing with successive cycles to a maximum with Gondwana assembly which may reflect enhanced subduction-erosion. We demonstrate that the juvenile Hf signal carries important information on prevailing global magmatic style, and thus tectonic processes.

  5. Stable hydrogen isotopes record the summering grounds of eastern red bats (Lasiurus borealis

    Directory of Open Access Journals (Sweden)

    Cortney L. Pylant

    2014-10-01

    Full Text Available Bats face numerous threats associated with global environmental change, including the rapid expansion of wind-energy facilities, emerging infectious disease, and habitat loss. An understanding of the movement and migration patterns of these highly dispersive animals would help reveal how spatially localized the impacts from these threats are likely to be on bat populations, thus aiding in their conservation. Stable hydrogen isotope ratios (δ2H can be used to infer regions where bats have foraged during the summer molt season, thus allowing an assessment of summering location and distance of movement of bats sampled during other times of year. However, a major impediment to the application of δ2H for inference of bat movements is that the relationship between δ2H of bat hair and precipitation tends to be species specific and is still unknown for some key species of conservation concern. We addressed this issue by using geo-referenced museum specimens to calibrate the relationship between δ2H of hair (δ2Hhair and long-term δ2H of growing-season precipitation (δ2HGSprecip at the site of collection for eastern red bats (Lasiurus borealis, one of the main species of bats experiencing large numbers of fatalities at wind-energy facilities in North America. Based on comparison of δ2Hhair and δ2HGSprecip values for males we estimated a period of molt of June 14–August 7. Within this period, male and female red bats exhibited a significant positive relationship between δ2Hhair and δ2HGSprecip. These results establish the relationship between δ2Hhair and δ2HGSprecip for red bats, which is necessary for the use of δ2Hhair to infer the movement and migration patterns of this important species. These results provide a critical resource to conservation biologists working to assess the impacts of environmental change on bat populations.

  6. Investigating the hydrological significance of stalagmite geochemistry (Mg, Sr) using Sr isotope and particulate element records across the Late Glacial-to-Holocene transition

    Science.gov (United States)

    Belli, R.; Borsato, A.; Frisia, S.; Drysdale, R.; Maas, R.; Greig, A.

    2017-02-01

    The trace element and Sr isotope records in two coeval stalagmites characterized by different growth rates and flow regimes at Savi cave (Grotta Savi, NE Italy) reveal different sources and incorporation mechanisms for Mg and Sr. Mg is sourced primarily from dissolved cave host rock while particulate Mg derived from soil plays a subordinate role. The presence of particulate-borne Mg is inferred from the co-variation of Mg and particle-associated elements (Th, Al and Mn) which are preferentially concentrated in open columnar calcite layers. Variation in Mg concentrations corrected for particle-influenced components, the Mgc parameter, is controlled by water-rock interaction, with higher and lower Mgc during dry and wet phases, respectively. This is thought to reflect incongruent dissolution of Mg-rich phases. Correction of Sr concentrations for contributions from airborne exogenic Sr, based on 87Sr/86Sr ratios, yields the bedrock-only contribution (Src). Src variation in stalagmite calcite is influenced by speleothem growth rate and by variation of the calcite-water Sr partitioning in wet and dry phases, and only to a minor extent by incongruent dissolution of Mg-rich phases. Concentration profiles for Mgc and Srcg (corrected for growth rate effects) show inverse correlations and are inferred to show hydrological significance which is captured in a hydrological index, HI. We suggest HI provides robust information on water-rock interaction related to hydrological changes and can be utilized in both wet and semi-arid environments, provided the corrections for soil Mg and exogenic Sr can be applied with confidence. Application of the HI index allows correction of Grotta Savi oxygen isotope data, to yield a δ18Oc time series that shows when changes in moisture sources and atmospheric reorganization, or changes in moisture amount, were significant. This is especially evident during the Younger Dryas (YD). The Savi record supports the concept of a two-phase YD, marked by

  7. Time-resolved record of 236U and 239,240Pu isotopes from a coral growing during the nuclear testing program at Enewetak Atoll (Marshall Islands).

    Science.gov (United States)

    Froehlich, M B; Chan, W Y; Tims, S G; Fallon, S J; Fifield, L K

    2016-12-01

    A comprehensive series of nuclear tests were carried out by the United States at Enewetak Atoll in the Marshall Islands, especially between 1952 and 1958. A Porites Lutea coral that was growing in the Enewetak lagoon within a few km of all of the high-yield tests contains a continuous record of isotopes, which are of interest (e.g. 14 C, 236 U, 239,240 Pu) through the testing period. Prior to the present work, 14 C measurements at ∼2-month resolution had shown pronounced peaks in the Δ 14 C data that coincided with the times at which tests were conducted. Here we report measurements of 236 U and 239,240 Pu on the same coral using accelerator mass spectrometry, and again find prominent peaks in the concentrations of these isotopes that closely follow those in 14 C. Consistent with the 14 C data, the magnitudes of these peaks do not, however, correlate well with the explosive yields of the corresponding tests, indicating that smaller tests probably contributed disproportionately to the debris that fell in the lagoon. Additional information about the different tests can also be obtained from the 236 U/ 239 Pu and 240 Pu/ 239 Pu ratios, which are found to vary dramatically over the testing period. In particular, the first thermonuclear test, Ivy-Mike, has characteristic 236 U/ 239 Pu and 240 Pu/ 239 Pu signatures which are diagnostic of the first arrival of nuclear test material in various archives. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Electrochemically controlled iron isotope fractionation

    Science.gov (United States)

    Black, Jay R.; Young, Edward D.; Kavner, Abby

    2010-02-01

    Variations in the stable isotope abundances of transition metals have been observed in the geologic record and trying to understand and reconstruct the physical/environmental conditions that produced these signatures is an area of active research. It is clear that changes in oxidation state lead to large fractionations of the stable isotopes of many transition metals such as iron, suggesting that transition metal stable isotope signatures could be used as a paleo-redox proxy. However, the factors contributing to these observed stable isotope variations are poorly understood. Here we investigate how the kinetics of iron redox electrochemistry generates isotope fractionation. Through a combination of electrodeposition experiments and modeling of electrochemical processes including mass-transport, we show that electron transfer reactions are the cause of a large isotope separation, while mass transport-limited supply of reactant to the electrode attenuates the observed isotopic fractionation. Furthermore, the stable isotope composition of electroplated transition metals can be tuned in the laboratory by controlling parameters such as solution chemistry, reaction overpotential, and solution convection. These methods are potentially useful for generating isotopically-marked metal surfaces for tracking and forensic purposes. In addition, our studies will help interpret stable isotope data in terms of identifying underlying electron transfer processes in laboratory and natural samples.

  9. Deep circulation changes in the South Atlantic since the Last Glacial Maximum from Nd isotope and multi-proxy records

    Science.gov (United States)

    Wei, R.; Abouchami, W.; Zahn, R.; Masque, P.

    2016-01-01

    We report down-core sedimentary Nd isotope (εNd) records from two South Atlantic sediment cores, MD02-2594 and GeoB3603-2, located on the western South African continental margin. The core sites are positioned downstream of the present-day flow path of North Atlantic Deep Water (NADW) and close to the Southern Ocean, which makes them suitable for reconstructing past variability in NADW circulation over the last glacial cycle. The Fe-Mn leachates εNd records show a coherent decreasing trend from glacial radiogenic values towards less radiogenic values during the Holocene. This trend is confirmed by εNd in fish debris and mixed planktonic foraminifera, albeit with an offset during the Holocene to lower values relative to the leachates, matching the present-day composition of NADW in the Cape Basin. We interpret the εNd changes as reflecting the glacial shoaling of Southern Ocean waters to shallower depths combined with the admixing of southward flowing Northern Component Water (NCW). A compilation of Atlantic εNd records reveals increasing radiogenic isotope signatures towards the south and with increasing depth. This signal is most prominent during the Last Glacial Maximum (LGM) and of similar amplitude across the Atlantic basin, suggesting continuous deep water production in the North Atlantic and export to the South Atlantic and the Southern Ocean. The amplitude of the εNd change from the LGM to Holocene is largest in the southernmost cores, implying a greater sensitivity to the deglacial strengthening of NADW at these sites. This signal impacted most prominently the South Atlantic deep and bottom water layers that were particularly deprived of NCW during the LGM. The εNd variations correlate with changes in 231Pa/230Th ratios and benthic δ13C across the deglacial transition. Together with the contrasting 231Pa/230Th: εNd pattern of the North and South Atlantic, this indicates a progressive reorganization of the AMOC to full strength during the Holocene.

  10. Actinides record, power calculations and activity for present isotopes in the spent fuel of a BWR

    International Nuclear Information System (INIS)

    Enriquez C, P.; Ramirez S, J. R.; Lucatero, M. A.

    2012-10-01

    The administration of spent fuel is one of the more important stages of the nuclear fuel cycle, and this has become a problem of supreme importance in countries that possess nuclear reactors. Due to this in this work, the study on the actinides record and present fission products to the discharge of the irradiated fuel in a light water reactor type BWR is shown, to quantify the power and activity that emit to the discharge and during the cooling time. The analysis was realized on a fuel assembly type 10 x 10 with an enrichment average of 3.69 wt % in U-235 and the assembly simulation assumes four cycles of operation of 18 months each one and presents an exposition of 47 G Wd/Tm to the discharge. The module OrigenArp of the Scale 6 code is the computation tool used for the assembly simulation and to obtain the results on the actinides record presents to the fuel discharge. The study covers the following points: a) Obtaining of the plutonium vector used in the fuel production of mixed oxides, and b) Power calculation and activity for present actinides to the discharge. The results presented in this work, correspond at the same time immediate of discharge (0 years) and to a cooling stage in the irradiated fuel pool (5 years). (Author)

  11. Valence coordinate contributions to zero-point energy shifts due to hydrogen isotope substitutions

    International Nuclear Information System (INIS)

    Oi, Takao; Ishida, Takanobu

    1986-01-01

    The orthogonal approximation method for the zero-point energy (ZPE) developed previously has been applied to analyze the shifts in the ZPE, δ(ZPE), due to monodeuterium substitutions in methane, ethylene, ethane and benzene in terms of elements of F and G matrices. The δ(ZPE) can be expressed with a reasonable precision as a sum of contributions of individual valence coordinates and correction terms consisting of the first-order interactions between the coordinates. A further refinement in the precision is achieved by a set of small number of second-order terms, which can be estimated by a simple procedure. (author)

  12. Contribution to the study of luminous sources for uranium isotope measurements by emission spectrometry

    International Nuclear Information System (INIS)

    Leichnam, J.P.; Capitini, R.

    1964-01-01

    After a brief summary of results obtained with different hollow cathode luminous sources, the reasons for which they cannot be more widely used are given: an insufficient luminosity when uranium oxides are used in the cathode hollow; the large amount of sample required when it is metallic; the impossibility of effecting a chemical purification of the sample. Electrode-less discharge tubes excited by high frequency whose qualities (luminosity, stability, rapidity of preparation starting from small amounts of sample in various chemical forms, in particular iron) satisfy the conditions laid down for the measurement of uranium 235 by interferometry are used. Tho production process for such lamps is given together with the method of excitation. Examples of recordings obtained with an interferometer of the 'HYPEAC' type and a small grating spectrometer give an idea of the spectral qualities of these sources. (authors) [fr

  13. A Compound-Specific Hydrogen Isotope Record at the Onset of Ocean Anoxic Event 2, Kaiparowits Plateau, Southern Utah

    Science.gov (United States)

    Todes, J.; Jones, M. M.; Sageman, B. B.; Osburn, M. R.

    2017-12-01

    Rhythmic lithologic variations (limestone-shale couplets) interpreted to reflect Milankovitch cycles occur at the onset of Ocean Anoxic Event 2 (OAE2) in deposits of the Western Interior Seaway. These couplets have been interpreted to reflect climate cycles: however, the physical mechanism(s) through which climate cycles were translated to the sedimentary record during peak greenhouse conditions remain unsettled. Although glacioeustasy has been considered, variance in surface ocean temperature, ocean circulation, or local hydrology may be more plausible options. Compound-specific hydrogen isotope ratios (δ2H) of n-alkanes and other biomarkers may provide a means to evaluate such mechanisms. Since sedimentary alkanes are direct products of plants and membrane lipid diagenesis and are resistant to secondary hydrogen exchange during thermal maturation at low (chain length distributions suggest low thermal maturity and the possible preservation of primary δ2H values. Short and long chain ­n-alkanes are potentially sourced from planktonic biomass and terrestrial plants, respectively, enabling a comparison of climatic processes between marine and terrestrial settings. Biomarkers, including both steranes and hopanes, are also preserved and reflect putative source organisms and local paleoenvironmental conditions. Facies-specific δ2H analysis will allow for evaluation of changes in the dominant source of atmospheric moisture in the Western Interior during orbitally-forced climate cycles. Organic matter deposited during periods of northerly Boreal influence would have a depleted 2H-isotope composition relative to those deposited during periods of more southerly Tethys influence. In this model, these variations are reflected by lithology - limestone deposition would occur during warm, evaporative Tethys-dominated times, while cooler, wetter Boreal periods would promote shale deposition.

  14. Lead isotope ratios in six lake sediment cores from Japan Archipelago: Historical record of trans-boundary pollution sources

    International Nuclear Information System (INIS)

    Hosono, Takahiro; Alvarez, Kelly; Kuwae, Michinobu

    2016-01-01

    Sediment cores from six lakes situated from north to south on the Japanese Archipelago were collected during 2009–2010 to investigate the hypothesis that deposition of lead (Pb) was coming from East Asia (including China, South Korea and eastern part of Russia). Accumulation rates and ages of the lake sediment were estimated by the "2"1"0Pb constant rate of supply model and "1"3"7Cs inputs to reconstruct the historical trends of Pb accumulation. Cores from four lakes located in the north and central Japan, showed clear evidence of Pb pollution with a change in the "2"0"6Pb/"2"0"7Pb and "2"0"8Pb/"2"0"7Pb ratios in the recent sediment as compared to the deeper sediment. Among the six studied lakes, significant inputs of anthropogenic lead emissions were observed at Lake Mikazuki (north Hokkaido in north Japan), Lake Chokai (north of Honshu), and Lake Mikuriga (central part of Honshu). Pb isotopic comparison of collected core sediment and previously reported data for wet precipitation and aerosols from different Asian regions indicate that, before 1900, Pb accumulated in these three lakes was not affected by trans-boundary sources. Lake Mikazuki started to receive Pb emissions from Russia in early 1900s, and during the last two decades, this lake has been affected by trans-boundary Pb pollution from northern China. Lake Chokai has received Pb pollutant from northern China since early 1900s until 2009, whereas for the Lake Mikuriga the major Pb contaminant was transported from southern China during the past 100 years. The results of our study demonstrate that Japan Archipelago has received trans-boundary Pb emissions from different parts of East Asian region depending on location, and the major source region has changed historically. - Highlights: • Historical trend of Pb pollution was recorded in six Japanese Lakes. • Pb concentration and Pb isotope ratios were determined for sediment cores. • High [Pb] and less radiogenic Pb isotope ratios were observed since

  15. Lead isotope ratios in six lake sediment cores from Japan Archipelago: Historical record of trans-boundary pollution sources

    Energy Technology Data Exchange (ETDEWEB)

    Hosono, Takahiro, E-mail: hosono@kumamoto-u.ac.jp [Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Alvarez, Kelly [Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Kuwae, Michinobu [Senior Research Fellow Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan)

    2016-07-15

    Sediment cores from six lakes situated from north to south on the Japanese Archipelago were collected during 2009–2010 to investigate the hypothesis that deposition of lead (Pb) was coming from East Asia (including China, South Korea and eastern part of Russia). Accumulation rates and ages of the lake sediment were estimated by the {sup 210}Pb constant rate of supply model and {sup 137}Cs inputs to reconstruct the historical trends of Pb accumulation. Cores from four lakes located in the north and central Japan, showed clear evidence of Pb pollution with a change in the {sup 206}Pb/{sup 207}Pb and {sup 208}Pb/{sup 207}Pb ratios in the recent sediment as compared to the deeper sediment. Among the six studied lakes, significant inputs of anthropogenic lead emissions were observed at Lake Mikazuki (north Hokkaido in north Japan), Lake Chokai (north of Honshu), and Lake Mikuriga (central part of Honshu). Pb isotopic comparison of collected core sediment and previously reported data for wet precipitation and aerosols from different Asian regions indicate that, before 1900, Pb accumulated in these three lakes was not affected by trans-boundary sources. Lake Mikazuki started to receive Pb emissions from Russia in early 1900s, and during the last two decades, this lake has been affected by trans-boundary Pb pollution from northern China. Lake Chokai has received Pb pollutant from northern China since early 1900s until 2009, whereas for the Lake Mikuriga the major Pb contaminant was transported from southern China during the past 100 years. The results of our study demonstrate that Japan Archipelago has received trans-boundary Pb emissions from different parts of East Asian region depending on location, and the major source region has changed historically. - Highlights: • Historical trend of Pb pollution was recorded in six Japanese Lakes. • Pb concentration and Pb isotope ratios were determined for sediment cores. • High [Pb] and less radiogenic Pb isotope ratios

  16. Contributions of detrital subsidies to aboveground spiders during secondary succession, revealed by radiocarbon and stable isotope signatures.

    Science.gov (United States)

    Haraguchi, Takashi F; Uchida, Masao; Shibata, Yasuyuki; Tayasu, Ichiro

    2013-04-01

    Prey subsidies originating from detritus add nutrients and energy to arboreal communities. Measurement of this subsidy is required in the understanding of how food web dynamics respond to changes in surrounding environments. Shrub spiders are one of the key predators involved in food web coupling. We evaluate the effects of potential changes in prey availabilities during secondary succession on the contribution of subsidy from detrital food webs to shrub spiders and how different spider feeding guilds used the subsidy of prey from detrital food webs. We measured the relative importance of the subsidy for the spider feeding guilds, using the ratios of stable isotopes of C (δ(13)C), and N (δ(15)N) and C isotope discrimination (Δ(14)C). Diet age was calculated from Δ(14)C values, because old diet ages of spiders indicate that the spiders consume prey from detrital food sources. Dominant aerial prey (Diptera) had a distinctively old diet age compared with arboreal prey, which indicates that aerial prey were subsidized from detrital food webs. Sit-and-wait spiders tended to have an older diet age than active hunting spiders, which indicates that sit-and-wait spiders depended more on subsidies. Diet age varied only slightly for spiders in stands of different ages, indicating that rates at which spiders use grazing and detrital prey are probably determined more by foraging strategies and not by stand age. A dominance of sit-and-wait predators will lead to higher detrital subsidy inputs in shrub habitats. This study highlights the effect of shrub spider community structure (feeding guild composition) on the volume of the subsidy received from the detrital food web.

  17. Isotopic signatures suggest important contributions from recycled gasoline, road dust and non-exhaust traffic sources for copper, zinc and lead in PM10 in London, United Kingdom

    Science.gov (United States)

    Dong, Shuofei; Ochoa Gonzalez, Raquel; Harrison, Roy M.; Green, David; North, Robin; Fowler, Geoff; Weiss, Dominik

    2017-09-01

    The aim of this study was to improve our understanding of what controls the isotope composition of Cu, Zn and Pb in particulate matter (PM) in the urban environment and to develop these isotope systems as possible source tracers. To this end, isotope ratios (Cu, Zn and Pb) and trace element concentrations (Fe, Al, Cu, Zn, Sb, Ba, Pb, Cr, Ni and V) were determined in PM10 collected at two road sites with contrasting traffic densities in central London, UK, during two weeks in summer 2010, and in potential sources, including non-combustion traffic emissions (tires and brakes), road furniture (road paint, manhole cover and road tarmac surface) and road dust. Iron, Ba and Sb were used as proxies for emissions derived from brake pads, and Ni, and V for emissions derived from fossil fuel oil. The isotopic composition of Pb (expressed using 206Pb/207Pb) ranged between 1.1137 and 1.1364. The isotope ratios of Cu and Zn expressed as δ65CuNIST976 and δ66ZnLyon ranged between -0.01‰ and +0.51‰ and between -0.21‰ and +0.33‰, respectively. We did not find significant differences in the isotope signatures in PM10 over the two weeks sampling period and between the two sites, suggesting similar sources for each metal at both sites despite their different traffic densities. The stable isotope composition of Pb suggests significant contribution from road dust resuspension and from recycled leaded gasoline. The Cu and Zn isotope signatures of tires, brakes and road dust overlap with those of PM10. The correlation between the enrichments of Sb, Cu, Ba and Fe in PM10 support the previously established hypothesis that Cu isotope ratios are controlled by non-exhaust traffic emission sources in urban environments (Ochoa Gonzalez et al., 2016). Analysis of the Zn isotope signatures in PM10 and possible sources at the two sites suggests significant contribution from tire wear. However, temporary additional sources, likely high temperature industrial emissions, need to be invoked

  18. Fallout isotope chronology of the near-surface sediment record of Lake Bolătău.

    Science.gov (United States)

    Bihari, Árpád; Karlik, Máté; Mîndrescu, Marcel; Szalai, Zoltán; Grădinaru, Ionela; Kern, Zoltán

    2018-01-01

    Fallout isotope ( 210 Pb ex, 137 Cs and 241 Am) based dating has been carried out on the near-surface sediment core collected from Lake Bolătău-Feredeu (Bukovina, Romania). The motivation was to improve the chronology of this recent section in connection with significant fluctuations observed in sediment accumulation rates, particle size distribution and primordial radioisotope (i.e. 40 K and 232 Th) composition. Previously only an extrapolation of a broad-range OxCal age-depth model, which was based on 8 AMS radiocarbon dates from the deeper part of a parallel sediment sequence and tentatively validated for the upper part using the double peaks of the 137 Cs activity concentration distribution, was available for the studied section (1-24 cm). Parallel to the previous 137 Cs measurement, 210 Pb and 226 Ra (for a more detailed, 210 Pb ex -based chronology), 241 Am (for an additional time-marker), as well as 40 K and 232 Th concentrations have also been determined by gamma-spectrometry. In case of the 210 Pb ex -based chronology, due to a large deviation from a pure exponential distribution, the Constant Flux (CF) model has been used for the calculation of sediment ages and accumulation rates. Although the broad-range OxCal and the CF model were broadly similar down to 22 cm, the 210 Pb ex -based ages are clearly superior in terms of uncertainty in the uppermost 12 cm, while the broad-range model has smaller uncertainty below 20 cm (>150 years). The CF model gave an average mass accumulation rate of (0.08 ± 0.03) g cm -2 yr -1 for sections 0-11 cm, and (0.03 ± 0.01) g cm -2 yr -1 for sections 12-22 cm, respectively. Significant changes have been observed in the depth distribution of both the particle size distribution and the elemental/isotopic composition of the sediment record, most likely related to the variation observable in the intensity and volume of precipitation in the catchment. The obtained high-resolution records of Lake Bolătău, including

  19. On the Use of Biomineral Oxygen Isotope Data to Identify Human Migrants in the Archaeological Record: Intra-Sample Variation, Statistical Methods and Geographical Considerations.

    Directory of Open Access Journals (Sweden)

    Emma Lightfoot

    Full Text Available Oxygen isotope analysis of archaeological skeletal remains is an increasingly popular tool to study past human migrations. It is based on the assumption that human body chemistry preserves the δ18O of precipitation in such a way as to be a useful technique for identifying migrants and, potentially, their homelands. In this study, the first such global survey, we draw on published human tooth enamel and bone bioapatite data to explore the validity of using oxygen isotope analyses to identify migrants in the archaeological record. We use human δ18O results to show that there are large variations in human oxygen isotope values within a population sample. This may relate to physiological factors influencing the preservation of the primary isotope signal, or due to human activities (such as brewing, boiling, stewing, differential access to water sources and so on causing variation in ingested water and food isotope values. We compare the number of outliers identified using various statistical methods. We determine that the most appropriate method for identifying migrants is dependent on the data but is likely to be the IQR or median absolute deviation from the median under most archaeological circumstances. Finally, through a spatial assessment of the dataset, we show that the degree of overlap in human isotope values from different locations across Europe is such that identifying individuals' homelands on the basis of oxygen isotope analysis alone is not possible for the regions analysed to date. Oxygen isotope analysis is a valid method for identifying first-generation migrants from an archaeological site when used appropriately, however it is difficult to identify migrants using statistical methods for a sample size of less than c. 25 individuals. In the absence of local previous analyses, each sample should be treated as an individual dataset and statistical techniques can be used to identify migrants, but in most cases pinpointing a specific

  20. Cenozoic History of the Equatorial Indian Ocean Recorded by Nd Isotopes: The Closure of the Indonesian Gateway

    Science.gov (United States)

    Gourlan, A. T.; Meynadier, L.; Allegre, C. J.

    2005-12-01

    The northward tectonic motion of the Australian plate and the evolution of the Indonesian Island Arcs through the last 20 Ma, generate changes in the flow and the origin of the circulation between the Pacific and the Southern Indian Oceans. Indeed, the emergence of the Indonesian Archipelago and probably the rapid uplift of the island of Halmahera have dramatically reduced the Indonesian Gateway. However, the precise dating of this event is still a matter of debate. The Neodymium isotopic composition of marine sediments is an extremely good proxy to reconstruct the major changes in the past ocean circulation. The residence time of Nd is shorter than the circulation time of the global ocean. Therefore, the Nd isotopic composition varies between the different ocean basins and is function of changes in source provenances, paleocirculation, orogenic processes, and intensity of weathering on the continents as well as on the volcanic arcs. To reconstruct the evolution of the oceanic flow from the Pacific to the equatorial Indian Ocean since the Miocene, we have applied on high carbonates content sediments a leaching technique using acetic acid. The reliability of our technique has been assessed by comparison with the Hydroxylamine hydrochloride technique developed by Bayon et al (1). The Nd isotopic composition is determinated in the past seawater from the record in Fe-Mn oxides. The sedimentary sequences are accurately dated using bio and chimiostratigraphy. Three ODP Sites were chosen in the Indian Ocean with a water depth ranging from 1600 to 2800 m and mutually distant by about 3000 km. From West to East: Site 761 which is at the western edge of the Indonesian Gateway on the central northeastern part of the Wombat Plateau off NW Australia, Site 757 is located on the south of the Ninetyeast ridge and Site 707 is located in the western tropical Indian Ocean near the Seychelles Islands. Our data are compared with the first results from Site 807 located in the Pacific

  1. Geochemical and isotopic determination of deep groundwater contributions and salinity to the shallow groundwater and surface water systems, Mesilla Basin, New Mexico, Texas, and Mexico

    Science.gov (United States)

    Robertson, A.; Carroll, K. C.; Kubicki, C.; Purtshert, R.

    2017-12-01

    The Mesilla Basin/Conejos-Médanos aquifer system, extending from southern New Mexico to Chihuahua, Mexico, is a priority transboundary aquifer under the 2006 United States­-Mexico Transboundary Aquifer Assessment Act. Declining water levels, deteriorating water quality, and increasing groundwater use by municipal, industrial, and agricultural users on both sides of the international border raise concerns about long-term aquifer sustainability. Relative contributions of present-day and "paleo" recharge to sustainable fresh groundwater yields has not been determined and evidence suggests that a large source of salinity at the distal end of the Mesilla Basin is saline discharge from deep groundwater flow. The magnitude and distribution of those deep saline flow paths are not determined. The contribution of deep groundwater to discharge and salinity in the shallow groundwater and surface water of the Mesilla Basin will be determined by collecting discrete groundwater samples and analyzing for aqueous geochemical and isotopic tracers, as well as the radioisotopes of argon and krypton. Analytes include major ions, trace elements, the stable isotopes of water, strontium and boron isotopes, uranium isotopes, the carbon isotopes of dissolved inorganic carbon, noble gas concentrations and helium isotope ratios. Dissolved gases are extracted and captured from groundwater wells using membrane contactors in a process known as ultra-trace sampling. Gas samples are analyzed for radioisotope ratios of krypton by the ATTA method and argon by low-level counting. Effectiveness of the ultra-trace sampling device and method was evaluated by comparing results of tritium concentrations to the krypton-85 content. Good agreement between the analyses, especially in samples with undetectable tritium, indicates that the ultra-trace procedure is effective and confirms that introduction of atmospheric air has not occurred. The geochemistry data indicate a complex system of geochemical

  2. Geostatistical analysis and isoscape of ice core derived water stable isotope records in an Antarctic macro region

    Science.gov (United States)

    Hatvani, István Gábor; Leuenberger, Markus; Kohán, Balázs; Kern, Zoltán

    2017-09-01

    Water stable isotopes preserved in ice cores provide essential information about polar precipitation. In the present study, multivariate regression and variogram analyses were conducted on 22 δ2H and 53 δ18O records from 60 ice cores covering the second half of the 20th century. Taking the multicollinearity of the explanatory variables into account, as also the model's adjusted R2 and its mean absolute error, longitude, elevation and distance from the coast were found to be the main independent geographical driving factors governing the spatial δ18O variability of firn/ice in the chosen Antarctic macro region. After diminishing the effects of these factors, using variography, the weights for interpolation with kriging were obtained and the spatial autocorrelation structure of the dataset was revealed. This indicates an average area of influence with a radius of 350 km. This allows the determination of the areas which are as yet not covered by the spatial variability of the existing network of ice cores. Finally, the regional isoscape was obtained for the study area, and this may be considered the first step towards a geostatistically improved isoscape for Antarctica.

  3. Stable carbon and oxygen isotope ratios of annual rings of pinus radiata provide an integrative record of canopy gas exchange

    International Nuclear Information System (INIS)

    Barbour, M.M.; Farquhar, G.D.

    2000-01-01

    Full text: Seasonal variation in δ 13 C and δ 18 O of cellulose from annual rings of Pinus radiata growing at each of three sites in New Zealand was measured. The three sites differed in annual water balance, temperature, and vapour pressure deficit, and these differences were reflected in cellulose δ 13 C and δ 18 O. Specific events such as drought or heavy rain were recorded as peaks and troughs in enrichment. A canopy-level combined photosynthesis and conductance model was linked to a model of soil water content and δ 18 O of xylem water to allow daily prediction of δ 13 C and δ 18 O of cellulose. A photosynthesis-weighted average of δ 13 C and δ 18 O was calculated for each sampling period. Each sample represented between 3 and 30 days, depending on stem growth rate. The timing and amplitude of changes in δ 13 C were predicted accurately by the model, while general seasonal patterns and event related peaks in δ 18 O enrichment were well predicted. These results suggest that stable isotope ratios of cellulose from annual rings reflect the canopy response to interactions between site-specific and seasonal variation in climatic conditions and soil water availability

  4. An isotopic and modelling study of flow paths and storage in Quaternary calcarenite, SW Australia: implications for speleothem paleoclimate records

    Science.gov (United States)

    Treble, Pauline C.; Bradley, Chris; Wood, Anne; Baker, Andy; Jex, Catherine N.; Fairchild, Ian J.; Gagan, Michael K.; Cowley, Joan; Azcurra, Cecilia

    2013-03-01

    We investigated the distinctive shallow sub-surface hydrology of the southwest Western Australia (SWWA) dune calcarenite using observed rainfall and rainfall δ18O; soil moisture, cave drip rate and dripwater δ18O over a six-year period: August 2005-March 2012. A lumped parameter hydrological model is developed to describe water fluxes and drip δ18O. Comparison of observed data and model output allow us to assess the critical non-climatic karst hydrological processes that modify the precipitation δ18O signal and discuss the implications for speleothem paleoclimate records from this cave and those with a similar karst setting. Our findings include evidence of multiple reservoirs, characterised by distinct δ18O values and recharge responses ('low' and 'high' flow sites). Dripwaters exhibit δ18O variations in wet versus dry years at low-flow sites receiving diffuse seepage from the epikarst with an attenuated isotopic composition that approximates mean rainfall. Recharge from high-magnitude rain events is stored in a secondary reservoir which is associated with high-flow dripwater that is 1‰ lower than our monitored low-flow sites (δ18O). One drip site is characterised by mixed-flow behaviour and exhibits a non-linear threshold response after the cessation of drainage from a secondary reservoir following a record dry year (2006). Additionally, our results yield a better understanding of the vadose zone hydrology and dripwater characteristics in Quaternary age dune limestones. We show that flow to our monitored sites is dominated by diffuse flow with inferred transit times of less than one year. Diffuse flow appears to follow vertical preferential paths through the limestone reflecting differences in permeability and deep recharge into the host rock.

  5. Contribution of long-range transport to the ozone levels recorded in the Northeast of Portugal

    Science.gov (United States)

    Gama, C.; Nunes, T.; Marques, M. C.; Ferreira, F.

    2009-04-01

    In the past four years (2004-2007), measurements carried out at Lamas de Olo, the only air quality monitoring background station in the Northeast of Portugal, showed high ozone concentrations (97,7±29,7 g.m-3). This remote site, located in the middle of Alvão Natural Park, in Portugal, 1086 m asl, plays a significant role on the total amount of exceedances registered in the national air quality network. The analysis of the data recorded at this monitoring station revealed an annual cycle of ozone concentrations similar to the ones observed in other background sites of the Northern Hemisphere (Monks, 2000; Vingarzan and Taylor, 2003). This common feature comprises a distinct maximum during spring (peaking during the month of April). Nevertheless it is during the summer that the hourly concentrations are higher, due to the typical atmospheric and meteorological conditions that promote photochemical pollution episodes. Photochemical pollution episodes can be related with production of ozone in a local scale or in a global scale due to the transportation of polluted air masses. For this reason analysing these events is crucial to fully understand the behaviour of ozone in the Northeast of Portugal, in order to adopt the correct long-term policies. With the purpose of studying the influence of long-range transport on the ozone levels recorded at Lamas de Olo, a cluster analysis was performed on 96-hour back trajectories air masses. Different trajectory clusters represent air masses with different source regions of atmospheric pollutants and the influence of these regions on the atmospheric composition at the arrival point (receptor) of the trajectories can therefore be assessed (EMPA, 2008). The back trajectories were simulated 4 times per day, using HYSPLIT model. A "bottom-up" cluster methodology was used to group trajectories into clusters according to their characteristics, for several time periods with similar ozone levels and/or distributions. Ozone average

  6. Cenozoic Uplift and Climate Change of the Northeast Tibetan Plateau: Evidence from Leaf Wax Stable Isotopic Records

    Science.gov (United States)

    Hou, M.; Zhuang, G.; Wu, M.

    2017-12-01

    Topics about the deformation history and uplift mechanism of Tibetan Plateau have been largely debated in the past few decades. Different geodynamic models present different predictions on the mountain building processes and hence the surface uplift history. For example, one tectonic model suggests a rapid uplift (>1.0 to 2.0 km) of the Tibetan Plateau in the period of ca. 10 to 8 Ma as result of isostatic rebound due to the removal of over-thickened mental lithosphere beneath. Whilst the stepwise uplift model infers that the high topography was growing progressively from south to north with the Northeast Tibetan Plateau being built in the Pliocene to present. In this case, the timing of Cenozoic uplift of Northeast Tibetan Plateau would provide information for distinguishing competing geodynamic processes. The stable isotope based paleoaltimetry holds the key to answering when the high topography was built. Additionally, the evolution of Cenozoic Asian climate was argued to be closely related to the high topography built up on the Tibetan Plateau since the India-Asian collision and/or impacted by the global change. To understand when the high topography was built and how the growth of Tibetan Plateau impacted the climate, we reconstructed the long-term histories of paleohydrology from hinterland and foreland basins in the Northeast Tibetan Plateau. We applied the compound-specific isotope hydrogen analysis to leaf wax n-alkanes (δ2Hn-alk) that are preserved in well-dated stratigraphic series (ca. 24 Ma to the present) in the Northeast Tibetan Plateau. The newly reconstructed δ2Hn-alk supports the inference of high topography on the Northeast Tibetan Plateau was built during the middle to late Miocene. Our inference is consistent with sedimentary and basement rock studies that show fundamental changes in facies and provenance and exhumation history. The new δ2Hn-alk record also reveals that the regional climate became drier since the middle Miocene following the

  7. 18O isotopic characterisation of non-point source contributed heavy metals (Zn and Cu) contamination of groundwater

    International Nuclear Information System (INIS)

    Datta, P.S.; Manjaiah, K.M.; Tyagi, S.K.

    1999-01-01

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

  8. How Can Sport Biomechanics Contribute to the Advance of World Record and Best Athletic Performance?

    Science.gov (United States)

    Li, Li

    2012-01-01

    Modern history has evidence that sport biomechanics provide valuable contribution in the pursuit of "faster, higher, and stronger." In this article, the contribution of sport biomechanics to the Olympic Games has been divided into three different categories: improve the physical capacity of the athletes, develop innovative techniques in…

  9. Estimation of different source contributions to sediment organic matter in an agricultural-forested watershed using end member mixing analyses based on stable isotope ratios and fluorescence spectroscopy.

    Science.gov (United States)

    Derrien, Morgane; Kim, Min-Seob; Ock, Giyoung; Hong, Seongjin; Cho, Jinwoo; Shin, Kyung-Hoon; Hur, Jin

    2018-03-15

    The two popular source tracing tools of stable isotope ratios (δ 13 C and δ 15 N) and fluorescence spectroscopy were used to estimate the relative source contributions to sediment organic matter (SeOM) at five different river sites in an agricultural-forested watershed (Soyang Lake watershed), and their capabilities for the source assignment were compared. Bulk sediments were used for the stable isotopes, while alkaline extractable organic matter (AEOM) from sediments was used to obtain fluorescent indices for SeOM. Several source discrimination indices were fully compiled for a range of the SeOM sources distributed in the catchments of the watershed, which included soils, forest leaves, crop (C3 and C4) and riparian plants, periphyton, and organic fertilizers. The relative source contributions to the river sediment samples were estimated via end member mixing analysis (EMMA) based on several selected discrimination indices. The EMMA based on the isotopes demonstrated that all sediments were characterized by a medium to a high contribution of periphyton ranging from ~30% to 70% except for one site heavily affected by forest and agricultural fields with relatively high contributions of terrestrial materials. The EMMA based on fluorescence parameters, however, did not show similar results with low contributions from forest leaf and periphyton. The characteristics of the studied watershed were more consistent with the source contributions determined by the isotope ratios. The discrepancy in the EMMA capability for source assignments between the two analytical tools can be explained by the limited analytical window of fluorescence spectroscopy for non-fluorescent dissolved organic matter (FDOM) and the inability of AEOM to represent original bulk particulate organic matter (POM). Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado, Utah, and Texas using mobile isotopic methane analysis based on Cavity Ringdown Spectroscopy

    Science.gov (United States)

    Rella, Chris; Winkler, Renato; Sweeney, Colm; Karion, Anna; Petron, Gabrielle; Crosson, Eric

    2014-05-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of carbon dioxide emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation, provided that the fugitive emissions of methane are kept under control. A key step in assessing these emissions in a given region is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis, using the isotopic carbon signature to distinguish between natural gas and landfills or ruminants. We present measurements of methane using a mobile spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in three intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, the Uintah basin in Utah, and the Barnett Shale in Texas. Performance of the CRDS isotope analyzer is presented, including precision, calibration, stability, and the potential for measurement bias due to other atmospheric constituents. Mobile isotope measurements of individual sources and in the nocturnal boundary layer have been combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities. The fraction of total methane emissions in the Denver-Julesburg basin attributed to natural gas emissions is 78 +/- 13%. In the Uinta basin, which has no other significant sources of methane, the fraction is 96% +/- 15%. In addition, results from the Barnett shale are presented, which includes a major urban center (Dallas / Ft. Worth). Methane emissions in this region are spatially highly heterogeneous. Spatially-resolved isotope and concentration measurements are interpreted using a simple emissions model to

  11. High resolution stable isotopes and elemental analysis on benthic foraminifera: a 4000 yr BP record from the ria de Muros (NW Spain)

    Science.gov (United States)

    Pena, L. D.; Francés, G.; Diz, P.; Nombela, M. A.; Alejo, I.

    2003-04-01

    Carbon and oxygen stable isotopes and ICP-OES elemental ratio concentrations (Mg/Ca, Sr/Ca, Ba/Ca) from core EUGC-3B (42 45.10'N; 9 02.23'W, at 38 m.b.s.l. and 410 cm length) were measured over monospecific benthic foraminiferal samples (Nonion fabum) ranging over the last 4500 yr BP. From the oldest analysed sample (289 cm) to the core top, stable isotopes signal shows that the whole record can be separated into 4 intervals lasting each of them about 1000 yr. The lowermost interval (4300-3000 yr BP) is characterized by relatively stable delta 18O values (mean 1.77 per mil). Delta 13C is relatively low except for a maximum around 3300 cal BP (-1.50 per mil). An abrupt decrease down to the minimum value in delta 13C (-4.41 per mil) is accomplished in approximately 200 yr. Mg/Ca and Ba/Ca match perfectly this event, both of them showing the respective maxima values. Sr/Ca has a very similar behaviour to that of delta 13C but with smoother fluctuations. We attribute high values of delta 13C, Sr/Ca and Ba/Ca to periods of enhanced coastal productivity, probably due to reinforced upwelling events in the region. According to Mg/Ca signal this reinforcement took place during a relatively warmer period. The most remarkable feature during the two next periods (3000-1900 yr BP and 1900-1000 yr BP) consists of a stepwise increase of delta 13C values punctuated by a sharp decrease at the end of each interval. All the remaining proxies exhibit a nearly constant trend over these intervals. Each period can be interpreted as a weak enhance of marine productivity that the system does not hold up and finally aborts. The most recent interval represents the establishment of current conditions in the coastal system. The most conspicuous event from this interval consists of an abrupt decrease of the delta 18O that lasted for 300 yr. This event could be correlated with the well recognized warm climatic event known as the Medieval Warm Period. However the Mg/Ca ratio does not show high

  12. The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets

    Science.gov (United States)

    Zazzo, A.; Balasse, M.; Passey, B. H.; Moloney, A. P.; Monahan, F. J.; Schmidt, O.

    2010-06-01

    Quantitative reconstruction of paleodiet by means of sequential sampling and carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite ( ɛD-E), as well as of the timing and duration of the enamel mineralization process (amelogenesis). To better constrain these parameters, we performed a series of controlled feeding experiments on sheep ranging in age from 6 to 24 months-old. Twenty-eight lambs and 14 ewes were fed isotopically distinct diets for different periods of time, and then slaughtered, allowing the timing and rate of molar growth to be determined. High resolution sampling and stable carbon isotope analysis of breath CO 2 performed on six individuals following a diet-switch showed that 70-90% of dietary carbon had turned over in less than 24 h. Sequential sampling and carbon isotopic analysis was performed on the first (M 1) and second (M 2) lower molars of four lambs as well as on the third lower molar (M 3) of 11 ewes. The changes in diet were recorded in all molars. We found that the length of enamel matrix apposition is approximately one-quarter of the final tooth length during crown extension, and that enamel maturation spans slightly less than 3 months in M 1, and 4 months in M 2 and M 3. Portions of enamel in equilibrium with dietary carbon were used to calculate ɛD-E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. The tooth enamel forward model of Passey and Cerling (2002) closely predicted the amplitude of isotope changes recorded in tooth enamel, but slightly underestimated the rate of isotope change, suggesting that the rate of accumulation of carbonate during maturation may not be constant over time. Although stable isotope profiles in tooth

  13. Contribution of bulk mass spectrometry isotopic analysis to characterization of materials in the framework of CMX-4

    International Nuclear Information System (INIS)

    Kuchkin, A.; Stebelkov, V.; Zhizhin, K.; Lierse von Gostomski, Ch.; Kardinal, Ch.; Loi, E.; Keegan, E.; Kristo, M.J.

    2018-01-01

    Seven laboratories used the results of bulk uranium isotopic analysis by either inductively coupled plasma mass spectrometry (ICP-MS) or thermal ionization mass spectrometry (TIMS) for characterization of the samples in the Nuclear Forensic International Technical Working Group fourth international collaborative material exercise, CMX-4. Comparison of the measured isotopic compositions of uranium in three exercise samples is implemented for identifying any differences or similarities between the samples. The role of isotopic analyses in the context of a real nuclear forensic investigation is discussed. Several limitations in carrying out ICP-MS or TIMS analysis in CMX-4 are noted. (author)

  14. Erosion of the Alps: use of Rb-Sr isotopic data from molassic sediments to identify the ages of the metamorphism recorded by the eroded rocks

    International Nuclear Information System (INIS)

    Henry, P.; Deloule, E.

    1994-01-01

    Rb-Sr isotopic data from Oligocene and Miocene peri-alpine molassic sediments allow us to identify the different periods for which the eroded rocks have or have not recorded an alpine metamorphism. The Chattian and the Burdigalian sediments result from the erosion of rocks for which the latest metamorphic event was variscan, while the Stampian, Aquitanian and ''Helvetian'' sediments show evidence for the erosion of rocks which have recorded alpine metamorphic events. The application of this method to old detrital sediments could permit determination of the ages of the tectonic events which occurred in the sediment source regions. (authors). 18 refs., 6 figs

  15. Contribution of deep sourced carbon from hydrocarbon seeps to sedimentary organic carbon: Evidence from Δ14C and δ13C isotopes

    Science.gov (United States)

    Feng, D.; Peckmann, J.; Peng, Y.; Liang, Q.; Roberts, H. H.; Chen, D.

    2017-12-01

    Sulfate-driven anaerobic oxidation of methane (AOM) limits the release of methane from marine sediments and promotes the formation of carbonates close to the seafloor along continental margins. It has been established that hydrocarbon seeps are a source of dissolved inorganic and organic carbon to marine environments. However, questions remain about the contribution of deep sourced carbon from hydrocarbon seeps to the sedimentary organic carbon pool. For a number of hydrocarbon seeps from the South China Sea and the Gulf of Mexico, the portion of modern carbon was determined based on natural radiocarbon abundances (Δ14C) and stable carbon isotope (δ13Corganic carbon) compositions of the non-carbonate fractions extracted from authigenic carbonates. Samples from both areas show a mixing trend between ideal planktonic organic carbon (δ13C = -22‰ VPDB and 90% modern carbon) and the ambient methane. The δ13Corganic carbon values of non-carbonate fractions from three ancient seep deposits (northern Italy, Miocene; western Washington State, USA, Eocene to Oligocene) confirm that the proxy can be used to constrain the record of sulfate-driven AOM through most of Earth history by measuring the δ13C values of organic carbon. This study reveals the potential of using δ13C values of organic carbon to discern seep and non-seep environments. This new approach is particularly promising when authigenic carbonate is not present in ancient sedimentary environments. Acknowledgments: The authors thank BOEM and NOAA for their years' support of the deep-sea dives. Funding was provided by the NSF of China (Grants: 41422602 and 41373085).

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

    Science.gov (United States)

    Schollaen, Karina; Helle, Gerhard

    2013-04-01

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

  17. Invite yourself to the table: librarian contributions to the electronic medical record.

    Science.gov (United States)

    Brandes, Susan; Wells, Karen; Bandy, Margaret

    2013-01-01

    Librarians from Exempla Healthcare hospitals initiated contact with the chief medical information officer regarding evidence-based medicine activities related to the development of the system's Electronic Medical Record (EMR). This column reviews the librarians' involvement in specific initiatives that included providing comparative information on point-of-care resources to integrate into the EMR, providing evidence as needed for the order sets being developed, and participating with clinicians on an evidence-based advisory committee.

  18. Precipitation stable isotope records from the northern Hengduan Mountains in China capture signals of the winter India-Burma Trough and the Indian Summer Monsoon

    Science.gov (United States)

    Yu, Wusheng; Tian, Lide; Yao, Tandong; Xu, Baiqing; Wei, Feili; Ma, Yaoming; Zhu, Haifeng; Luo, Lun; Qu, Dongmei

    2017-11-01

    This project reports results of the first precipitation stable isotope (δ18 O and δD) time series produced for Qamdo in the northern Hengduan Mountains in the southeastern Tibetan Plateau. The data showed that the fluctuations of precipitation stable isotopes at Qamdo during the different seasons revealed various moisture sources. The westerlies and local recycling moisture dominated at the study area before the pre-monsoon and after the post-monsoon seasons, which resulted in similar trends of both precipitation stable isotopes and temperature. The marine moisture was transported to the northern Hengduan Mountains by the winter India-Burma Trough combined with convection. Consequently, stable isotopes in subsequent precipitation were occasionally observed to decrease suddenly. However, δ18 O and δD values of precipitation at Qamdo were lower during the monsoon period and the duration of those low values was longer because of the effects of the Indian Summer Monsoon and the strengthening convection. Our findings indicate that the effects of seasonal precipitation differences caused by various climate systems, including the winter India-Burma Trough and Indian Summer Monsoon, need to be considered when attempting to interpret tree-ring and ice core records for the Hengduan Mountains.

  19. Toward explaining the Holocene carbon dioxide and carbon isotope records: Results from transient ocean carbon cycle-climate simulations

    Science.gov (United States)

    Menviel, L.; Joos, F.

    2012-03-01

    The Bern3D model was applied to quantify the mechanisms of carbon cycle changes during the Holocene (last 11,000 years). We rely on scenarios from the literature to prescribe the evolution of shallow water carbonate deposition and of land carbon inventory changes over the glacial termination (18,000 to 11,000 years ago) and the Holocene and modify these scenarios within uncertainties. Model results are consistent with Holocene records of atmospheric CO2 and δ13C as well as the spatiotemporal evolution of δ13C and carbonate ion concentration in the deep sea. Deposition of shallow water carbonate, carbonate compensation of land uptake during the glacial termination, land carbon uptake and release during the Holocene, and the response of the ocean-sediment system to marine changes during the termination contribute roughly equally to the reconstructed late Holocene pCO2 rise of 20 ppmv. The 5 ppmv early Holocene pCO2 decrease reflects terrestrial uptake largely compensated by carbonate deposition and ocean sediment responses. Additional small contributions arise from Holocene changes in sea surface temperature, ocean circulation, and export productivity. The Holocene pCO2 variations result from the subtle balance of forcings and processes acting on different timescales and partly in opposite direction as well as from memory effects associated with changes occurring during the termination. Different interglacial periods with different forcing histories are thus expected to yield different pCO2 evolutions as documented by ice cores.

  20. Carbon, nitrogen and oxygen isotope fractionation during food cooking: Implications for the interpretation of the fossil human record.

    Science.gov (United States)

    Royer, Aurélien; Daux, Valérie; Fourel, François; Lécuyer, Christophe

    2017-08-01

    Stable isotope data provide insight into the reconstruction of ancient human diet. However, cooking may alter the original stable isotope compositions of food due to losses and modifications of biochemical and water components. To address this issue, carbon, nitrogen and oxygen isotope ratios were measured on meat aliquots sampled from various animals such as pork, beef, duck and chicken, and also from the flesh of fishes such as salmon, European seabass, European pilchard, sole, gilt-head bream, and tuna. For each specimen, three pieces were cooked according to the three most commonly-known cooking practices: boiling, frying and roasting on a barbecue. Our data show that cooking produced isotopic shifts up to 1.8‰, 3.5‰, and 5.2‰ for δ 13 C, δ 15 N, and δ 18 O values, respectively. Such variations between raw and cooked food are much greater than previously estimated in the literature; they are more sensitive to the type of food rather than to the cooking process itself, except in the case of boiling. Reconstructions of paleodietary may thus suffer slight bias in cases of populations with undiversified diets that are restrained toward a specific raw or cooked product, or using a specific cooking mode. In cases of oxygen isotope compositions from skeletal remains (bones, teeth), they not only constitute a valuable proxy for reconstructing past climatic conditions, but they could also be used to improve our knowledge of past human diet. © 2017 Wiley Periodicals, Inc.

  1. The Northern Apennines palynological record as a contribute for the reconstruction of the Messinian palaeoenvironments

    Science.gov (United States)

    Bertini, Adele

    2006-06-01

    The Messinian stage has long been associated with an overall warm and dry climate whereas recent researches indicate either a warm and humid or a cool and dry climate. The integrated stratigraphic record of vegetation and climatic changes from Northern Apennines sites provides the solution to this apparent contradiction. Its integration with the updated geological and sedimentological studies provides additional data for the reconstruction of the depositional palaeoenvironments in both marginal and deeper sub-basins of the Apennines foredeep. The onset of the Mediterranean salinity crisis (MSC) is recorded in the Gessoso-Solfifera of the Vena del Gesso (marginal sub-basin). Cyclical humid conditions, corresponding to precession minima, developed during the deposition of the shales interbedded with the gypsum (5.9 to 5.6 Ma); some cooler events took also place under the effects of global (glacial stadials) and regional factors (Apennines uplift). At present no major changes from moist to dry conditions are attested to just before the salinity crisis, as well as in Sicily. So climate did not play a major role in the onset of the MSC despite the favourable context provided by inferred thermo-xeric conditions in southern Italy. A drier episode indicated by the expansion of the open vegetation including the northward migration of Lygeum postdates the onset of the salinity crisis of about 400 kyr, in the lower post-evaporitic deposits of Maccarone (deeper sub-basin). It falls within a period of global warming whereas at a regional scale it could correlate p.p. to the evaporite deposition in deeper basins and to hiatuses in the marginal basins of Sicily and of the western sector of Northern Apennines. Its sudden end, about 100 kyr later, in coincidence with a significant increase of Pinaceae, indicates a turnover in the terrestrial setting not linked to major climate changes but possibly to a complex interaction between other palaeoenvironmental factors (e.g., tectonics

  2. A contribution key for the first recorded spider (Arachnidae: Aranae fauna from Sheringal, Khyber Pakhtunkhwa, Pakistan

    Directory of Open Access Journals (Sweden)

    Farzana Khan Perveen

    2016-03-01

    Full Text Available The spiders (Arthropoda: Arachnida have a hard cephalothorax and soft abdomen. They are environmental indicators and play an important role in biological control of pests and vectors. The present study was conducted to prepare the key for the first recorded spider fauna during June 2013-July 2014 in 6 quadrates of Sheringal, i.e., Daramdala, Doki, Guryaal, Samang, Shahoor and Sia-Sheringal, Dir Upper (DU, Khyber Pakhtunkhwa (KP, Pakistan. During the present research, 10 species belong to 7 families, and 10 genera were recorded. The family Sparassidae was the largest among collected families (nSparassidae=19, its body was larger than others, abdomen was narrow at posterior, cephalothorax region was broad and brown, chelicearae were forwarded, legs were strong, body have hairs grey to brown and they were harmless and speedy. Gnphosidae family was the smallest among collected families (nGnphosidae=3, their eyes were heterogeneous, their inner margin of chelicerae were with a wide serrated lamina, posterior row of eyes were much longer than anterior, with lateral rounded maxillae. While the family Hersiliidae was the unique in collected families (nHersiliidae=6, as they are known as two-tail spiders, they have enlarged spinnerets, their male grow up to 8 mm and female up to 10 mm, they have 2 tails and are mimic with host plants. It was concluded that the majority of the collected species belong to the family Sparassidae. It is recommended that further research may be conducted on arboreal and aquatic species of spiders in Sheringal, KP, Pakistan.

  3. Deciphering human-climate interactions in an ombrotrophic peat record: REE, Nd and Pb isotope signatures of dust supplies over the last 2500 years (Misten bog, Belgium)

    Science.gov (United States)

    Fagel, N.; Allan, M.; Le Roux, G.; Mattielli, N.; Piotrowska, N.; Sikorski, J.

    2014-06-01

    A high-resolution peat record from Eastern Belgium reveals the chronology of dust deposition for the last 2500 years. REE and lithogenic elements in addition to Nd and Pb isotopes were measured in a 173 cm age-dated peat profile and provide a continuous chronology of dust source and intensity. Calculated dust flux show pronounced increases c. 300 BC, 600 AD, 1000 AD, 1200 AD and from 1700 AD, corresponding to local and regional human activities combined with climate change. The Industrial Revolution samples (1700-1950 AD) are characterised by a significant enrichment in Sc-normalised REE abundance (sum REE/Sc > 25) due to intensive coal combustion. For the pre-Industrial Revolution samples, the Sc-normalised REE abundance (10 climate. Combining REE abundance, fractionation between Light REE and Heavy REE and Nd isotope data in ombrotrophic peat allows one to distinguish between dust flux changes related to human and climate forcings.

  4. Isotope angiocardiography

    International Nuclear Information System (INIS)

    Stepinska, J.; Ruzyllo, W.; Konieczny, W.

    1979-01-01

    Method of technetium isotope 99 m pass through the heart recording with the aid of radioisotope scanner connected with seriograph and computer is being presented. Preliminary tests were carried out in 26 patients with coronary disease without or with previous myocardial infarction, cardiomyopathy, ventricular septal defect and in patients with artificial mitral and aortic valves. The obtained scans were evaluated qualitatively and compared with performed later contrast X-rays of the heart. Size of the right ventricle, volume and rate of left atrial evacuation, size and contractability of left ventricle were evaluated. Similarity of direct and isotope angiocardiographs, non-invasional character and repeatability of isotope angiocardiography advocate its usefulness. (author)

  5. Evidence for Slab Melt Contributions to the Mexican Volcanic Belt and Other Young Hot Slab Arcs from Lu-Hf Isotopes

    Science.gov (United States)

    Goldstein, S. L.; Cai, Y. M.; Langmuir, C. H.; Lagatta, A.; Straub, S. M.; Gomez-Tuena, A.; Martin Del Pozzo, A.

    2007-12-01

    Despite major advances in delineating the processes that govern magma generation at convergent margins, the problem persists of distinguishing slab, mantle wedge, and crustal contributions. A corrollary question is whether there is significant melting of subducted ocean crust. Especially in thick crust regions, the importance of crustal versus mantle contributions to lavas represents a long-standing fundamental issue in arc magma geochemistry. We show that frontal arc magmas from the Central Mexican Volcanic Belt (CMVB), including the large andesitic stratovolcanoes Popocatepetl and Nevado de Toluca, display negligible crustal contamination, and contain substantial contributions from melting of subducted Pacific ocean crust. Despite ca. 50 km thick continental crust, the CMVB erupts near primitive lavas including "high-Nb" alkaline basalts that show negligible "subduction signatures" in their trace element patterns. These "high-Nb" basalts define the regional mantle wedge composition in isotope-trace element space. The "normal" calcalkaline lavas form a negative correlation between Hf isotopes and Lu/Hf. One endmember is like the high Nb basalts representing the regional mantle wedge. The other endmember has higher Hf isotopes (approaching values of Pacific MORB) and very low Lu/Hf of less than 0.04 (e.g. compared to typical values of ca. 0.2 in Pacific MORB). The low Lu/Hf values require low degree partial melting of a source rich in garnet. The high Hf isotopes require a depleted mantle source with isotopes like Pacific MORB. Together the Lu-Hf data indicate a substantial component derived from melting of eclogitic Pacific ocean crust. A key feature of the data is that the stratovolcano lavas showing the largest slab melt signature also show the highest Hf isotope ratios and thus are more "depleted mantle-like" than the regional mantle wedge. Thus, the integrated data allow us to clearly distinguish between mantle and crustal sources in the CMVB and point to

  6. Post-Wisconsinan Chemical Weathering Rates and Trajectories From a 13,400-Year Sediment Core Record of Lead Isotopic Ratios in Maine

    Science.gov (United States)

    Perry, R. H.; Norton, S. A.; Koons, P. O.; Handley, M.

    2008-12-01

    Lead isotopic ratios recorded in a 5.3-m 13.4-ka 14C-dated lake sediment core from Sargent Mountain Pond, Maine (USA) are interpreted as an archive of post-glacial chemical weathering. Early weathering yielded highly radiogenic sediment from the preferential release of U and Th decay products (206Pb, 207Pb, and 208Pb) from accessory mineral phases in the catchment's predominantly-granitic till and bedrock relative to non-radiogenic 204Pb from the more abundant primary minerals. Values for 207Pb/206Pb in the sediment increased rapidly from 0.799 to 0.814 in the catchment's first 4,000 years of post-Wisconsinan weathering, and thereafter increased only slightly to just prior to the 19th century. Values for 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb decline over the same time-scale, as a result of decreasing radiogenic Pb being released from catchment weathering. Our results are consistent with: (1) the published interpretation of Pb isotopic variation in ferromanganese ocean crusts as a reflection of continental-scale glacial-interglacial chemical weathering cycles, (2) bench-scale whole-rock weathering experiments, and (3) soil chronosequence Pb isotope dissolution experiments and bridge the gap between short-term, mineral-scale experiments and long-term, ocean sediment records. We establish a time-scale for depletion of accessory minerals, and loss of their Pb isotopic signature at one catchment, and document the concurrent shift to slower primary mineral-controlled chemical weathering after deglaciation.

  7. The contribution of audio recording using portable digital voice recorders to the development of reflective practice with trainee teachers in a Further Education setting

    Directory of Open Access Journals (Sweden)

    Knill, Marta

    2011-06-01

    Full Text Available Developing reflective skills and habits during initial teacher education and progressing to deeper and more critical reflection are challenges for trainee teachers. This small-scale action research study investigates how two structured tasks using Digital Voice Recorders (DVRs initiated, sustained and improved reflection and reflective practice. Trainee teachers reported benefits in increased understanding of reflection, development of reflective skills, deepening of reflection and improvements in practice through joint reflection with Teacher Educators on specific aspects of teaching and learning. The structuring of the tasks with prompts and dialogue clearly contributed to the positive outcomes. The study suggests that use of the small, convenient and relatively low cost DVR technology has a place in learning to reflect.

  8. Rapid enhancement of chemical weathering recorded by extremely light seawater lithium isotopes at the Permian-Triassic boundary

    Science.gov (United States)

    Sun, He; Xiao, Yilin; Gao, Yongjun; Zhang, Guijie; Casey, John F.; Shen, Yanan

    2018-04-01

    Lithium (Li) isotope analyses of sedimentary rocks from the Meishan section in South China reveal extremely light seawater Li isotopic signatures at the Permian–Triassic boundary (PTB), which coincide with the most severe mass extinction in the history of animal life. Using a dynamic seawater lithium box model, we show that the light seawater Li isotopic signatures can be best explained by a significant influx of riverine [Li] with light δ7Li to the ocean realm. The seawater Li isotope excursion started ≥300 Ky before and persisted up to the main extinction event, which is consistent with the eruption time of the Siberian Traps. The eruption of the Siberian Traps exposed an enormous amount of fresh basalt and triggered CO2 release, rapid global warming, and acid rains, which in turn led to a rapid enhancement of continental weathering. The enhanced continental weathering delivered excessive nutrients to the oceans that could lead to marine eutrophication, anoxia, acidification, and ecological perturbation, ultimately resulting in the end-Permian mass extinction.

  9. Past 20,000-year history of Himalayan aridity: Evidence from oxygen isotope records in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.

    Late Quaternary climate history of the Himalayas is inferred from sea surface salinity (SSS) changes determined from the oxygen isotope in planktonic foraminifers, in a turbidity-free, 14C-dated core from the Bay of Bengal. The heaviest d18O...

  10. Autotrophic fixation of geogenic CO2 by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

    DEFF Research Database (Denmark)

    Beulig, Felix

    2015-01-01

    of radiocarbon and enriched in 13C compared to atmospheric CO2. Together, these isotopic signals allow us to distinguish C fixed by plants from C fixed by autotrophic microorganisms using their differences in 13C discrimination. We can then estimate that up to 27 % of soil organic matter in the 0–10 cm layer...... geogenic CO2 was fixed by plants or by CO2 assimilating microorganisms, we first used the proportional differences in radiocarbon and δ13C values to indicate the magnitude of discrimination of the stable isotopes in living plants. Deviation from this relationship was taken to indicate the presence...... can recycle significant amounts of carbon in wetland soils and might contribute to observed radiocarbon reservoir effects influencing Δ14C signatures in peat deposits....

  11. P contribution derived from phosphate solubilizing microorganism activity, rock phosphate and SP-36 determination by isotope "3"2P technique

    International Nuclear Information System (INIS)

    Anggi Nico Flatian; Iswandi Anas; Atang Sutandi; Ishak

    2016-01-01

    The "3"2P isotope technique has been used to trace P nutrients in the soil and soil-plant systems. The use of the isotope "3"2P has made it possible to differentiate the P contribution derived from phosphate solubilizing microorganism activity and the fertilizer P in the soil. The aims of the study were to obtain the quantitative data of P contribution derived from phosphate-solubilizing microorganism activity (Aspergillus niger and Burkholderia cepacia), rock phosphate and SP-36 through P uptake by the plants using isotope "3"2P technique and also to study the effects on growth and production of corn plants. The results were showed that phosphate-solubilizing microorganism, rock phosphate and SP-36 was produced specific activity ("3"2P) lower than control. The results were indicated that all treatments could contribute P for the plants. The lower specific activity was caused by supply P from rock phosphate and SP-36, and also was caused by solubilized of unavailable "3"1P from PSM activity, which decreased specific activity on labeled soil. The combination of phosphate-solubilizing microorganism and SP-36 treatments produced the highest P contribution, significantly higher than control and SP-36 only. Phosphate derived from combination of microorganism and SP-36 treatments ranging from 56.06% - 68.54% after 50 days planting, after 35 days planting, 51.96% - 59.65% on stover, 46.33% - 47.70% on grain and 53.02% - 59.87% on corn cob. In addition, the treatments could significantly support the plant growth and yield. It is expressed by increased number of leave at 35 days after planting, dry weight of leave at 35 days after planting and dry weight of grain. (author)

  12. The Cadmium Isotope Record of the Great Oxidation Event from the Turee Creek Group, Hamersley Basin, Australia

    Science.gov (United States)

    Abouchami, W.; Busigny, V.; Philippot, P.; Galer, S. J. G.; Cheng, C.; Pecoits, E.

    2016-12-01

    The evolution of the ocean, atmosphere and biosphere throughout Earth's history has impacted on the biogeochemistry of some key trace metals that are of particular importance in regulating the exchange between Earth's reservoirs. Several geochemical proxies exhibit isotopic shifts that have been linked to major changes in the oxygenation levels of the ancient oceans during the Great Oxygenation Event (GOE) between 2.45 and 2.2 Ga and the Neoproterozoic Oxygenation Event at ca. 0.6 Ga. Studies of the modern marine biogeochemical cycle of the transition metal Cadmium have shown that stable Cd isotope fractionation is mainly driven by biological uptake of light Cd into marine phytoplankton in surface waters leaving behind the seawater enriched in the heavy Cd isotopes. Here we use of the potential of this novel proxy to trace ancient biological productivity which remains an enigma, particularly during the early stages of Earth history. The Turee Creek Group in the Hamersley Basin, Australia, provides a continuous stratigraphic sedimentary section covering the GOE and at least two glacial events, offering a unique opportunity to examine the changes that took place during these periods and possibly constrain the evolution, timing and onset of oxygenic photosynthesis. Stable Cd isotope data were obtained on samples from the Boolgeeda Iron Fm. (BIFs), the siliciclastic and carbonate successions of Kungara (including the Meteorite Bore Member) and the Kazputt Fm., using a double spike technique by TIMS (ThermoFisher Triton) and Cd concentrations were determined by isotope dilution. The Boolgeeda BIFs have generally low Cd concentrations varying between 8 and 50ppb, with two major excursions marked by an increase in Cd content, reaching similar levels to those in the overlying Kungarra Fm. (≥150 ppb). These variations are associated with a large range in ɛ112/110Cd values (-2 to +2), with the most negative values typically found in the organic and Cd-rich shales and

  13. Water and carbon stable isotope records from natural archives: a new database and interactive online platform for data browsing, visualizing and downloading

    Science.gov (United States)

    Bolliet, Timothé; Brockmann, Patrick; Masson-Delmotte, Valérie; Bassinot, Franck; Daux, Valérie; Genty, Dominique; Landais, Amaelle; Lavrieux, Marlène; Michel, Elisabeth; Ortega, Pablo; Risi, Camille; Roche, Didier M.; Vimeux, Françoise; Waelbroeck, Claire

    2016-08-01

    Past climate is an important benchmark to assess the ability of climate models to simulate key processes and feedbacks. Numerous proxy records exist for stable isotopes of water and/or carbon, which are also implemented inside the components of a growing number of Earth system model. Model-data comparisons can help to constrain the uncertainties associated with transfer functions. This motivates the need of producing a comprehensive compilation of different proxy sources. We have put together a global database of proxy records of oxygen (δ18O), hydrogen (δD) and carbon (δ13C) stable isotopes from different archives: ocean and lake sediments, corals, ice cores, speleothems and tree-ring cellulose. Source records were obtained from the georeferenced open access PANGAEA and NOAA libraries, complemented by additional data obtained from a literature survey. About 3000 source records were screened for chronological information and temporal resolution of proxy records. Altogether, this database consists of hundreds of dated δ18O, δ13C and δD records in a standardized simple text format, complemented with a metadata Excel catalog. A quality control flag was implemented to describe age markers and inform on chronological uncertainty. This compilation effort highlights the need to homogenize and structure the format of datasets and chronological information as well as enhance the distribution of published datasets that are currently highly fragmented and scattered. We also provide an online portal based on the records included in this database with an intuitive and interactive platform (http://climateproxiesfinder.ipsl.fr/), allowing one to easily select, visualize and download subsets of the homogeneously formatted records that constitute this database, following a choice of search criteria, and to upload new datasets. In the last part, we illustrate the type of application allowed by our database by comparing several key periods highly investigated by the

  14. Filling the gap in Ca input-output budgets in base-poor forest ecosystems: The contribution of non-crystalline phases evidenced by stable isotopic dilution

    Science.gov (United States)

    van der Heijden, Gregory; Legout, Arnaud; Mareschal, Louis; Ranger, Jacques; Dambrine, Etienne

    2017-07-01

    In terrestrial ecosystems, plant-available pools of magnesium and calcium are assumed to be stored in the soil as exchangeable cations adsorbed on the surface of mineral and/or organic particles. The pools of exchangeable magnesium and calcium are measured by ion-exchange soil extractions. These pools are sustained in the long term by the weathering of primary minerals in the soil and atmospheric inputs. This conceptual model is the base of input-output budgets from which soil acidification and the sustainability of soil chemical fertility is inferred. However, this model has been questioned by data from long-term forest ecosystem monitoring sites, particularly for calcium. Quantifying the contribution of atmospheric inputs, ion exchange and weathering of both primary, secondary and non-crystalline phases to tree nutrition in the short term is challenging. In this study, we developed and applied a novel isotopic dilution technique using the stable isotopes of magnesium and calcium to study the contribution of the different soil phases to soil solution chemistry in a very acidic soil. The labile pools of Mg and Ca in the soil (pools in equilibrium with the soil solution) were isotopically labeled by spraying a solution enriched in 26Mg and 44Ca on the soil. Labeled soil columns were then percolated with a dilute acid solution during a 3-month period and the isotopic dilution of the tracers was monitored in the leaching solution, in the exchangeable (2 sequential 1 mol L-1 ammonium acetate extractions) and non-crystalline (2 sequential soil digestions: oxalic acid followed by nitric acid) phases. Significant amounts of Mg and Ca isotope tracer were recovered in the non-crystalline soil phases. These phases represented from 5% to 25% and from 24% to 50%, respectively, of the Mg and Ca labile pools during the experiment. Our results show that non-crystalline phases act as both a source and a sink of calcium and magnesium in the soil, and contribute directly to soil

  15. Carbon and oxygen isotope time series records of planktonic and benthic foraminifera from the Arabian Sea: Implications on upwelling processes

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Niitsuma, N.

    changes associated with the calci¢cation depth of these twospecies. Ingeneral, Globigerina bulloides exhibitsgreater N 18 O amplitude £uctuations compared to Pulle- niatina obliquiloculata and Uvigerina excellens (Fig.3).TherangeofN 18 Ochangesin...,thelocalbottomwatertem- perature changes associated with monsoon circu- lationwouldaccountforthe0.4xhighershiftin N 18 Onoticed atODPSite723. 4.3. Carbon isotopes The N 13 Cvaluesof Globigerina bulloides, Pulle- niatina obliquiloculata and Uvigerina excellens vary from 31.13 to 32...

  16. Early Solar System Alkali Fractionation Events Recorded by K-Ca Isotopes in the Yamato-74442 LL-Chondritic Breccia

    Science.gov (United States)

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

    2015-01-01

    Radiogenic ingrowth of Ca-40 due to decay of K-40 occurred early in the solar system history causing the Ca-40 abundance to vary within different early-former reservoirs. Marshall and DePaolo ] demonstrated that the K-40/Ca-40 decay system could be a useful radiogenic tracer for studies of terrestrial rocks. Shih et al. [3,4] determined 40K/40Ca ages of lunar granitic rock fragments and discussed the chemical characteristics of their source materials. Recently, Yokoyama et al. [5] showed the application of the K-40/Ca-40 chronometer for high K/Ca materials in ordinary chondrites (OCs). High-precision calcium isotopic data are needed to constrain mixing processes among early solar system materials and the time of planetesimal formation. To better constrain the solar system calcium isotopic compositions among astromaterials, we have determined the calcium isotopic compositions of OCs and an angrite. We further estimated a source K/Ca ratio for alkali-rich fragments in a chondritic breccia using the estimated solar system initial Ca-40/Ca-44.

  17. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado and Utah using mobile stable isotope (13CH4) analysis

    Science.gov (United States)

    Rella, Chris; Jacobson, Gloria; Crosson, Eric; Karion, Anna; Petron, Gabrielle; Sweeney, Colm

    2013-04-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of CO2 emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation. However, given that the global warming potential of methane is many times greater than that of carbon dioxide (Solomon et al. 2007), the importance of quantifying the fugitive emissions of methane throughout the natural gas production and distribution process becomes clear (Howarth et al. 2011). A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis. In particular, the 13CH4 signature of natural gas (-35 to -40 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-45 to -70 permil). In this paper we present measurements of mobile field 13CH4 using a spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in two intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, and the Uintah basin in Utah. Mobile isotope measurements in the nocturnal boundary layer have been made, over a total path of 100s of km throughout the regions, allowing spatially resolved measurements of the regional isotope signature. Secondly, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in these regions, by making measurements of the isotope ratio directly in the downwind plume from each source. These

  18. A 500 year sediment lake record of anthropogenic and natural inputs to Windermere (English Lake District) using double-spike lead isotopes, radiochronology, and sediment microanalysis.

    Science.gov (United States)

    Miller, Helen; Croudace, Ian W; Bull, Jonathan M; Cotterill, Carol J; Dix, Justin K; Taylor, Rex N

    2014-07-01

    A high-resolution record of pollution is preserved in recent sediments from Windermere, the largest lake in the English Lake District. Data derived from X-ray core scanning (validated against wavelength dispersive X-ray fluorescence), radiochronological techniques ((210)Pb and (137)Cs) and ultrahigh precision, double-spike mass spectrometry for lead isotopes are combined to decipher the anthropogenic inputs to the lake. The sediment record suggests that while most element concentrations have been stable, there has been a significant increase in lead, zinc, and copper concentrations since the 1930s. Lead isotope down-core variations identify three major contributory sources of anthropogenic (industrial) lead, comprising gasoline lead, coal combustion lead (most likely source is coal-fired steam ships), and lead derived from Carboniferous Pb-Zn mineralization (mining activities). Periods of metal workings do not correlate with peaks in heavy metals due to the trapping efficiency of up-system lakes in the catchment. Heavy metal increases could be due to flood-induced metal inwash after the cessation of mining and the weathering of bedrock in the catchment. The combination of sediment analysis techniques used provides new insights into the pollutant depositional history of Windermere and could be similarly applied to other lake systems to determine the timing and scale of anthropogenic inputs.

  19. Contribution to isotopic and chemical study of the aquifers in the area of Frecheirinha, State of Ceara, Brazil

    International Nuclear Information System (INIS)

    Siqueira, H.B. de; Santiago, M.M.F.

    1982-01-01

    The isotopic and chemical characteristics of the aquifers in the area of Frecheirinha (State of Ceara) have been analyzed. In a area of 3,000 scquare Kilometers three aquifers has been identified. Oxygen-18 measurements show that during the rainy season the piezometric level rises until reaching the surface. Thus the flow-water is a mixture of rainwater with stored under-groundwater. Chemical analysis shows all waters (except for samples 1, 2 and 3) are potable. (L.H.L.L.) [pt

  20. Information from uranium and thorium isotopes recorded in lake bottom sediment - Lake Kawaguchi. Attempt to evaluate environmental changes

    International Nuclear Information System (INIS)

    Sakaguchi, A.; Yamamoto, M.; Shimizu, T.; Sasaki, K.; Koshimizu, S.

    2003-01-01

    Lake sediments, as well as ice cores and marine sediments, have been used to reveal past environmental changes caused by both natural and artificial events with local and global scales. Particles in the lake originate from soil and other suspended matter which are carried in from the inflowing water or from direct discharge (lithogenous particles), and they are also formed in the lake as a result of the growth, metabolism and death of plants and animals (autogenous particles). The settling particles contain U and Th isotopes due to lithogenous particles (soil), and adsorbed U to the particles. Thorium has an exceedingly low solubility in water and is very strongly adsorbed onto particles. If we can distinguish these two different components in the mixture of U due to lithogenous particles themselves and adsorption fractions, the former might provide useful information on past environmental changes by natural events, while the latter information on past environmental changes by artificial events. In this paper, we aimed to test the above hypothesis using data on U and Th isotopes of sediment cores (0- ca. 40 cm depth, covering periods of past several hundred years) from 3 points in Lake Kawaguchi of Fuji-Goko in Japan. By using model equation and results obtained from analysis, we distinguished U due to lithogenous and autogenous particles. And these depth profiles were compared with changes in the rainfall during the period of 1933 - 2001. Although the changes in the 238 U/ 232 Th ratios with depth for lithogenous particles and rainfall do not fluctuate synchronously, some parts of depth coincided with each other. The results suggest strongly that variation in the U and Th isotopic ratios separated by model might be helpful in tracing the past environmental changes in regional scale. To check the usefulness of this method, physical and chemical data such as grain size, grain density, water content and biogenic SiO 2 in the sediment will be further compared with the

  1. Productivity, facies and stable-isotope records of OAE2 (Cenomanian - Turonian) in the NW European epicontinental sea: from the English Chalk to North Sea black shales

    Science.gov (United States)

    Jarvis, Ian; Olde, Kate; Trabucho-Alexandre, João; Gröcke, Darren

    2013-04-01

    The Late Cretaceous (100.5 - 66.0 Ma) provides perhaps the best example of how the Earth System may function under long-term extreme greenhouse conditions. Rapidly rising global temperatures indicate that we are heading 'back to the Cretaceous' within a few hundred years, so a better understanding of this time interval is essential. The beginning of the Late Cretaceous was characterized by a period of rapidly rising eustatic sea level, the Cenomanian transgression, which flooded continental margins and established large areas of new epicontinental sea that accumulated thick sequences of pelagic and hemipelagic carbonate (chalk). Highest global temperatures were reached during the early part of the Turonian Stage (93.9 - 89.8 Ma). This period of dramatic palaeoenvironmental change was accompanied by one the largest perturbations of the global carbon cycle in the Mesozoic: Oceanic Anoxic Event 2 (OAE2), which was characterized by a 500 kyr episode of oceanic anoxia, widespread black shale deposition, biotic turnover, and a large global positive carbon stable-isotope excursion (2 - 6 ‰ ∂13C) recorded in marine carbonates and both marine and terrestrial organic matter. The Cenomanian-Turonian boundary interval exposed at Eastbourne, southern England, has become established as a European reference section for OAE2. Here, and elsewhere in Europe, the base of the ∂13C excursion is coincident with a marked facies change from rhythmically bedded grey chalks and marls, to a >8 m thick package of dark greenish-grey marl - the Plenus Marl. The termination of OAE2 occurs 6 m above, in a package of pale-yellow-weathering nodular chalks with prominent marl seams. Sediments are organic lean (10 wt%. The onshore equivalent in eastern England (the Black Band) is similarly organic-rich, as are comparable sections in northern Germany (e.g. Wunstorf), indicating likely fully anoxic episodes within some NW European basins. The exact stratigraphic equivalence between the onshore

  2. A 60,000-year record of hydrologic variability in the Central Andes from the hydrogen isotopic composition of leaf waxes in Lake Titicaca sediments

    Science.gov (United States)

    Fornace, Kyrstin L.; Hughen, Konrad A.; Shanahan, Timothy M.; Fritz, Sherilyn C.; Baker, Paul A.; Sylva, Sean P.

    2014-12-01

    A record of the hydrogen isotopic composition of terrestrial leaf waxes (δDwax) in sediment cores from Lake Titicaca provides new insight into the precipitation history of the Central Andes and controls of South American Summer Monsoon (SASM) variability since the last glacial period. Comparison of the δDwax record with a 19-kyr δD record from the nearby Illimani ice core supports the interpretation that precipitation δD is the primary control on δDwax with a lesser but significant role for local evapotranspiration and other secondary influences on δDwax. The Titicaca δDwax record confirms overall wetter conditions in the Central Andes during the last glacial period relative to a drier Holocene. During the last deglaciation, abrupt δDwax shifts correspond to millennial-scale events observed in the high-latitude North Atlantic, with dry conditions corresponding to the Bølling-Allerød and early Holocene periods and wetter conditions during late glacial and Younger Dryas intervals. We observe a trend of increasing monsoonal precipitation from the early to the late Holocene, consistent with summer insolation forcing of the SASM, but similar hydrologic variability on precessional timescales is not apparent during the last glacial period. Overall, this study demonstrates the relative importance of high-latitude versus tropical forcing as a dominant control on glacial SASM precipitation variability.

  3. Stable isotope record in annually laminated lake sediments from Lake Żabińskie (NE Poland) for the last millennium.

    Science.gov (United States)

    Gabryś, Alicja; Piotrowska, Natalia; Tylmann, Wojciech; Bonk, Alicja; Filipiak, Janusz; Wacnik, Agnieszka; Hernandez-Almeida, Ivan; Grosjean, Martin

    2015-04-01

    Stable isotope record of carbon (13C) and oxygen (18O) has been analysed from an annually laminated sediment from Lake Zabinskie (Mazurian Lakeland, NE Poland) with high resolution (1-3 yrs). The sediment layers which were formed in each year during the last millennium contain information about environmental changes in the past. The calcite layers are formed in lake sediment in warm months of the year, therefore the reconstruction of summer climate variables in the past is potentially possible. The investigation of correlation between isotope dataset and instrumental climate data for years 1897-2008 AD confirmed that theory. The record of temperature, precipitation and SPEI (Standardised Precipitation Evaporation Index) coefficient, which is a combination of both temperature and precipitation, was tested. The strongest linear correlations were found for most samples for June, July, August (JJA) months but in some cases the correlation coefficient was stronger when also May was taken into account. For the whole 120-yrs series the correlation between δ18O and average JJA temperature is 0.007, average JJA precipitation is 0.16 and average JJA SPEI is 0.20. Analyzing the results for 1897-2008 we can distinguish period 1960-2008 with relevantly stronger correlations: R(temperature) = 0.19, R(precipitation) = 0.20 and R(SPEI) = 0.45. This period is connected with cessation of human activity close to Lake Zabinskie. Reconstruction of climate variables for the last millennium was made using transfer function obtained for calibration period (1897-2008). Reconstructions showed that known climate extremes like Medieval Warm Period, Little Ice Age with Sporer (1420-1570), Maunder (1645-1715) and Dalton (1790-1820) Minimum was recorded in sediment from Lake Zabinskie. The presented study is a part of the project "Climate of northern Poland during the last 1000 years: Constraining the future with the past (CLIMPOL)", funded within Polish-Swiss Research Programme. http://www.climpol.ug.edu.pl

  4. Estimating pathway-specific contributions to biodegradation in aquifers based on dual isotope analysis: Theoretical analysis and reactive transport simulations

    NARCIS (Netherlands)

    Centler, F.; Heße, F.; Thullner, M.

    2013-01-01

    At field sites with varying redox conditions, different redox-specific microbial degradation pathways contribute to total contaminant degradation. The identification of pathway-specific contributions to total contaminant removal is of high practical relevance, yet difficult to achieve with current

  5. Contribution to the hydrogeological, geochemical and isotopic study of Ain El Beidha and Merguellil (Kairouan plain) aquifers: Implication for the dam-aquifer relationship

    International Nuclear Information System (INIS)

    Ben Ammar, Safouan

    2007-01-01

    karst before reaching the Kairouan plain aquifer (springs). Groundwater under flow is estimated at 9 M m3 year-1 and the karstic spring flow is evaluated at 10 M m3 year-1. The spring waters show an intermediate isotope composition between dam reservoir water and the upper catchment of Ain el Beidha basin. The contribution of dam water in mixed water (spring) varies between 21 to 66% depending on time. Values from 18O and 2H ratio are well correlated with the karstic spring flow and with the water level in the reservoir. The hydrogeological study helped to understand the hydrodynamic functioning of the Kairouan plain aquifer system and identified a decline of the water table levels (1.5 m year-1). This decrease is explained mainly by over exploitation (4.8 M m3 year-1). The hydrochemical investigation indicated that the rock-water interaction is the main process contributing to the groundwater salinization. All the samples collected in the Merguellil basin are of the main hydrochemical type: Cl-SO4-Na. Stable isotope values measured in the upstream part of plain, closer the dam, differ from other parts of the aquifer, therefore suggesting a significant input from evaporated dam waters mixed with Ain el Beidha groundwater (spring water coming from the karst). This contamination can be observed as far as 7 km downstream. However, isotopic imprint of the previous recharge process (infiltration of wadi floods) are still noticeable. The residence time of the groundwater was estimated by carbon-14 dating that shows variable values of transit velocity of the groundwater ranging from 3.36 to 0.44 m year-1 depending on the groundwater flow and on the lithological variability of the aquifer. (Author).

  6. Middle Pleistocene Transition (MPT) in the Eastern Indian Ocean: a 2000 kyr planktic faunal and isotope record from DSDP site 214

    International Nuclear Information System (INIS)

    Gupta, Anil K.; Dhingra, Hitesh

    2004-01-01

    Planktic foraminiferal faunal and isotope data from Deep Sea Drilling Project (DSDP) Site 214 reveal a major change in surface water properties in the eastern Indian Ocean, coinciding with the mid-Pleistocene climate transition (MPT). A comparative study of Globigerinoides sacculifer (a surface dwelling, warm water, mixed layer tropical planktic foraminifera), Globorotalia menardii Complex (a deep dwelling, tropical species group), and Orbulina universa (an intermediate depth warm-water subtropical foraminifera) with the stable isotope record of Globigerinoides ruber suggests a warm, thick mixed layer in the eastern Indian Ocean during,∼ 2000 Kyr to ∼ 900 Kyr. Since,∼ 900 Kyr the surface water mass stratification weakened, and the mixed layer as well as thermocline were shallow. A decrease in the population abundance of Gs. sacculifer, together with a decrease in δ 13 C and increase in δ 18 O values suggest a continuous cool climate and increased surface productivity over the last ∼ 900 Kyr. This coincides with an increased variance in the 400 ∼Kyr component of Earth's eccentricity cycle. (author)

  7. Sub-annual North Pacific hydroclimate variability since 1450AD from updated St. Elias ice core isotope and accumulation rate records

    Science.gov (United States)

    Kreutz, K. J.; Campbell, S. W.; Winski, D.; Osterberg, E. C.; Kochtitzky, W. H.; Copland, L.; Dixon, D.; Introne, D.; Medrzycka, D.; Main, B.; Bernsen, S.; Wake, C. P.

    2017-12-01

    A growing array of high-resolution paleoclimate records from the terrestrial region bordering the Gulf of Alaska (GoA) continues to reveal details about ocean-atmosphere variability in the region during the Common Era. Ice core records from high-elevation ranges in proximity to the GoA provide key information on extratropical hydroclimate, and potential teleconnections to low latitude regions. In particular, stable water isotope and snow accumulation reconstructions from ice cores collected in high precipitation locations are uniquely tied to regional water cycle changes. Here we present new data collected in 2016 and 2017 from the St. Elias Mountains (Eclipse Icefield, Yukon Territories, Canada), including a range of ice core and geophysical measurements. Low- and high-frequency ice penetrating radar data enable detailed mapping of icefield bedrock topography and internal reflector stratigraphy. The 1911 Katmai eruption layer can be clearly traced across the icefield, and tied definitively to the coeval ash layer found in the 345 meter ice core drilled at Eclipse Icefield in 2002. High-resolution radar data are used to map spatial variability in 2015/16 and 2016/17 snow accumulation. Ice velocity data from repeat GPS stake measurements and remote sensing feature tracking reveal a clear divide flow regime on the icefield. Shallow firn/ice cores (20 meters in 2017 and 65 meters in 2016) are used to update the 345 meter ice core drilled at Eclipse Icefield in 2002. We use new algorithm-based layer counting software to improve and provide error estimates on the new ice core chronology, which extends from 2017 to 1450AD. 3D finite element modeling, incorporating all available geophysical data, is used to refine the reconstructed accumulation rate record and account for vertical and horizontal ice flow. Together with high-resolution stable water isotope data, the updated Eclipse record provides detailed, sub-annual resolution data on several aspects of the regional

  8. Sea-level records from the U.S. mid-Atlantic constrain Laurentide Ice Sheet extent during Marine Isotope Stage 3.

    Science.gov (United States)

    Pico, T; Creveling, J R; Mitrovica, J X

    2017-05-30

    The U.S. mid-Atlantic sea-level record is sensitive to the history of the Laurentide Ice Sheet as the coastline lies along the ice sheet's peripheral bulge. However, paleo sea-level markers on the present-day shoreline of Virginia and North Carolina dated to Marine Isotope Stage (MIS) 3, from 50 to 35 ka, are surprisingly high for this glacial interval, and remain unexplained by previous models of ice age adjustment or other local (for example, tectonic) effects. Here, we reconcile this sea-level record using a revised model of glacial isostatic adjustment characterized by a peak global mean sea level during MIS 3 of approximately -40 m, and far less ice volume within the eastern sector of the Laurentide Ice Sheet than traditional reconstructions for this interval. We conclude that the Laurentide Ice Sheet experienced a phase of very rapid growth in the 15 kyr leading into the Last Glacial Maximum, thus highlighting the potential of mid-field sea-level records to constrain areal extent of ice cover during glacial intervals with sparse geological observables.

  9. The organic carbon isotope of lacustrine sediments of the Upper Shahejie formation in Huanghua Depression: a record of sedimentary environment and productivity of an ancient lake

    International Nuclear Information System (INIS)

    Fei, Weiwei; Huang, Xiaoyan; Dai, Na; Zhong, Ningning

    2013-01-01

    -rich lamellae is the result of algae blooming and deposition in ancient lakes, as carbonate lamellae is the result of CaCO_3 saturation precipitation with CO_2 decreasing in surface water due to the algal blooming. Lamellar deposition pattern of the mudstone recorded the geological process of algae’s blooming, death and burial. (2) The carbon isotopic composition of organic matter can be a sensitive indicator of the relative significance of bioproductivity and redox conditions as the main factor controlling the formation of organic-rich sediments. δ"1"3C_o_r_g shows a positive correlation with TOC when bioproductivity dominated, however, a negative correlation when redox conditions dominated (Harris et al., 2004). The study on biomarker shows pristane/phytane ratios nearly constant throughout the interval, suggesting the redox environments remained stable. The negative correlation between pristane/phytane ratios and TOC is not obvious, whereas δ"1"3C_o_r_g shows a good positive correlation to TOC%, adjusted R is 0.89. Thus it can be seen that bioproductivity exerted a significant control on organic carbon accumulation in the upper of Shahejie Formation.

  10. Discriminating assimilants and decoupling deep- vs. shallow-level crystal records at Mount Adams using 238U-230Th disequilibria and Os isotopes

    Science.gov (United States)

    Jicha, B.R.; Johnson, C.M.; Hildreth, Wes; Beard, B.L.; Hart, G.L.; Shirey, S.B.; Singer, B.S.

    2009-01-01

    A suite of 23 basaltic to dacitic lavas erupted over the last 350??kyr from the Mount Adams volcanic field has been analyzed for U-Th isotope compositions to evaluate the roles of mantle versus crustal components during magma genesis. All of the lavas have (230Th/238U) > 1 and span a large range in (230Th/232Th) ratios, and most basalts have higher (230Th/232Th) ratios than andesites and dacites. Several of the lavas contain antecrysts (crystals of pre-existing material), yet internal U-Th mineral isochrons from six of seven lavas are indistinguishable from their eruption ages. This indicates a relatively brief period of time between crystal growth and eruption for most of the phenocrysts (olivine, clinopyroxene, plagioclase, magnetite) prior to eruption. One isochron gave a crystallization age that is ~ 20-25??ka older than its corresponding eruptive age, and is interpreted to reflect mixing of older and juvenile crystals or a protracted period of magma storage in the crust. Much of the eruptive volume since 350??ka consists of lavas that have small to moderate 230Th excesses (2-16%), which are likely inherited from melting of a garnet-bearing intraplate ("OIB-like") mantle source. Following melt generation and subsequent migration through the upper mantle, most Mt. Adams magmas interacted with young, mafic lower crust, as indicated by 187Os/188Os ratios that are substantially more radiogenic than the mantle or those expected via mixing of subducted material and the mantle wedge. Moreover, Os-Th isotope variations suggest that unusually large 230Th excesses (25-48%) and high 187Os/188Os ratios in some peripheral lavas reflect assimilation of small degree partial melts of pre-Quaternary basement that had residual garnet or Al-rich clinopyroxene. Despite the isotopic evidence for lower crustal assimilation, these processes are not generally recorded in the erupted phenocrysts, indicating that the crystal record of the deep-level 'cryptic' processes has been

  11. Autotrophic fixation of geogenic CO2 by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

    DEFF Research Database (Denmark)

    Beulig, Felix

    2015-01-01

    To quantify the contribution of autotrophic microorganisms to organic matter (OM) formation in soils, we investigated natural CO2 vents (mofettes) situated in a wetland in northwest Bohemia (Czech Republic). Mofette soils had higher soil organic matter (SOM) concentrations than reference soils due...... of radiocarbon and enriched in 13C compared to atmospheric CO2. Together, these isotopic signals allow us to distinguish C fixed by plants from C fixed by autotrophic microorganisms using their differences in 13C discrimination. We can then estimate that up to 27 % of soil organic matter in the 0–10 cm layer...... ranged up to 1.59 ± 0.16 μg gdw−1 d−1. We inferred that the negative δ13C shift was caused by the activity of autotrophic microorganisms using the Calvin–Benson–Bassham (CBB) cycle, as indicated from quantification of cbbL/cbbM marker genes encoding for RubisCO by quantitative polymerase chain reaction...

  12. Quantifying sediment source contributions in coastal catchments impacted by the Fukushima nuclear accident with carbon and nitrogen elemental concentrations and stable isotope ratios

    Science.gov (United States)

    Laceby, J. Patrick; Huon Huon, Sylvain; Onda, Yuichi; Evrard, Olivier

    2016-04-01

    The Fukushima Dai-ichi Nuclear Power Plant accidental release of radioactive contaminants resulted in the significant fallout of radiocesium over several coastal catchments in the Fukushima Prefecture. Radiocesium, considered to be the greatest risk to the short and long term health of the local community, is rapidly bound to fine soil particles and thus is mobilized and transported during soil erosion and runoff processes. As there has been a broad-scale decontamination of rice paddy fields and rural residential areas in the contaminated region, one important long term question is whether there is, or may be, a downstream transfer of radiocesium from forests that covered over 65% of the most contaminated region. Accordingly, carbon and nitrogen elemental concentrations and stable isotope ratios are used to determine the relative contributions of forests and rice paddies to transported sediment in three contaminated coastal catchments. Samples were taken from the three main identified sources: cultivated soils (rice paddies and fields, n=30), forest soils (n=45), and subsoils (channel bank and decontaminated soils, n = 25). Lag deposit sediment samples were obtained from five sampling campaigns that targeted the main hydrological events from October 2011 to October 2014. In total, 86 samples of deposited sediment were analyzed for particulate organic matter elemental concentrations and isotope ratios, 24 from the Mano catchment, 44 from the Niida catchment, and 18 from the Ota catchment. Mann-Whitney U-tests were used to examine the source discrimination potential of this tracing suite and select the appropriate tracers for modelling. The discriminant tracers were modelled with a concentration-dependent distribution mixing model. Preliminary results indicate that cultivated sources (predominantly rice paddies) contribute disproportionately more sediment per unit area than forested regions in these contaminated catchments. Future research will examine if there are

  13. Oxygen isotope geochemistry of the lassen volcanic center, California: Resolving crustal and mantle contributions to continental Arc magmatism

    Science.gov (United States)

    Feeley, T.C.; Clynne, M.A.; Winer, G.S.; Grice, W.C.

    2008-01-01

    This study reports oxygen isotope ratios determined by laser fluorination of mineral separates (mainly plagioclase) from basaltic andesitic to rhyolitic composition volcanic rocks erupted from the Lassen Volcanic Center (LVC), northern California. Plagioclase separates from nearly all rocks have ??18O values (6.1-8.4%) higher than expected for production of the magmas by partial melting of little evolved basaltic lavas erupted in the arc front and back-arc regions of the southernmost Cascades during the late Cenozoic. Most LVC magmas must therefore contain high 18O crustal material. In this regard, the ??18O values of the volcanic rocks show strong spatial patterns, particularly for young rhyodacitic rocks that best represent unmodified partial melts of the continental crust. Rhyodacitic magmas erupted from vents located within 3.5 km of the inferred center of the LVC have consistently lower ??18 O values (average 6.3% ?? 0.1%) at given SiO2 contents relative to rocks erupted from distal vents (>7.0 km; average 7.1% ?? 0.1%). Further, magmas erupted from vents situated at transitional distances have intermediate values and span a larger range (average 6.8% ?? 0.2%). Basaltic andesitic to andesitic composition rocks show similar spatial variations, although as a group the ??18O values of these rocks are more variable and extend to higher values than the rhyodacitic rocks. These features are interpreted to reflect assimilation of heterogeneous lower continental crust by mafic magmas, followed by mixing or mingling with silicic magmas formed by partial melting of initially high 18O continental crust (??? 9.0%) increasingly hybridized by lower ??18O (???6.0%) mantle-derived basaltic magmas toward the center of the system. Mixing calculations using estimated endmember source ??18O values imply that LVC magmas contain on a molar oxygen basis approximately 42 to 4% isotopically heavy continental crust, with proportions declining in a broadly regular fashion toward the

  14. Geochemical, Sulfur Isotopic Characteristics and Source Contributions of Size-Aggregated Aerosols Collected in Baring Head, New Zealand.

    Science.gov (United States)

    Li, J.; Michalski, G. M.; Davy, P.; Harvey, M.; Wilkins, B. P.; Katzman, T. L.

    2017-12-01

    Sulfate aerosols are critical to the climate, human health, and the hydrological cycle in the atmosphere, yet the sources of sulfate in aerosols are not completely understood. In this work, we evaluated the sources of sulfate in size-aggregated aerosols from the Southern Pacific Ocean and the land of New Zealand using geochemical and isotopic analyses. Aerosols were collected at Baring Head, New Zealand between 6/30/15 to 8/4/16 using two collectors, one only collects Southern Pacific Ocean derived aerosols (open-ocean collector), the other collects aerosols from both the ocean and the land (all-direction collector). Each collector is equipped with two filters to sample size-aggregated aerosols (fine aerosols: NSS-SO42-, 70%), while coarse aerosols are dominated by sea-salt sulfate. However, some NSS-SO42- was also observed in coarse aerosols collected in summer, suggesting the presence of accumulation mode NSS-SO42- aerosols, which is possibly due to high summer biogenic DMS flux. The sources of sulfur in NSS-SO42- could be further determined by their d34S values. DMS emission is likely the sole sulfur source in the open-ocean collector as it shows constant DMS-like d34S signatures (15-18‰) throughout the year. Meanwhile, the d34S of NSS-SO42- in the all-direction collector display a seasonal trend: summer time d34S values are higher and DMS-like (15-18‰), indicating DMS emission is the dominant sulfur source; winter time d34S values are lower ( 6-12‰), therefore the sulfur is likely sourced from both DMS emission and terrestrial S input with low d34S values, such as volcanic activities, fossil fuel and wood burning.

  15. A 10-yr record of stable isotope ratios of hydrogen and oxygen in precipitation at Calgary, Alberta, Canada

    International Nuclear Information System (INIS)

    Peng, Haidong; Mayer, Bernhard; Krouse, H. Roy; Harris, Stuart

    2004-01-01

    Short-term (0.5-3 d) precipitation samples were collected from January 1992 to December 2001 in Calgary, Alberta, Canada, and the stable isotope ratios of hydrogen ( 2 H/ 1 H) and oxygen ( 18 O/ 16 O) for these samples were determined. The 10-yr amount-weighted average δ 2 H and δ 18 O values of precipitation were -136.1 per mill and -17.9 per mill, respectively. Consistent with IAEA established practice, the following local meteoric water line (LMWL) for Calgary was derived using amount-weighted monthly average δ 2 H and δ 18 O values: δ 2 H = 7.68 δ 18 O -0.21 (r 2 = 0.96, n= 104) . The correlation equation between δ 2 H and δ 18 O values from individual samples was found to be δ 2 H = 7.10 δ 18 O -13.64 (r 2 = 0.95, n= 839) , which is different from the LMWL, exhibiting lower slope and intercept values. A comparison of δ 2 H and δ 18 O correlation equations with temperature during precipitation events showed a trend of decreasing slopes and intercepts with increasing temperature. Our data suggest that this is caused by incorporation of moisture derived from evaporation from water bodies and soils along the storm paths and by secondary evaporation between the cloud base and the ground during precipitation events. These processes compromise the usefulness of d-excess values as an indicator for the meteorological conditions in the maritime source regions. The δ 18 O temperature dependence at Calgary was found to be ∼ 0.44 per mill/deg C. The study shows that short-term sampling of individual precipitation events yields valuable information, which is not obtainable by the widely used monthly collection programs

  16. A 10-yr record of stable isotope ratios of hydrogen and oxygen in precipitation at Calgary, Alberta, Canada

    Science.gov (United States)

    Peng, Haidong; Mayer, Bernhard; Harris, Stuart; Krouse, H. Roy

    2004-04-01

    Short-term (0.5 3 d) precipitation samples were collected from January 1992 to December 2001 in Calgary, Alberta, Canada, and the stable isotope ratios of hydrogen (2H/1H) and oxygen (18O/16O) for these samples were determined. The 10-yr amount-weighted average δ2H and δ18O values of precipitation were -136.1‰ and -17.9‰, respectively. Consistent with International Atomic Energy Agency (IAEA) established practice, the following local meteoric water line (LMWL) for Calgary was derived using amount-weighted monthly average δ2H and δ18O values: δ2H = 7.68 δ18O -0.21 (r2= 0.96, n= 104). The correlation equation between δ2H and δ18O values from individual samples was found to be δ2H = 7.10 δ18O -13.64 (r2= 0.95, n= 839), which is different from the LMWL, exhibiting lower slope and intercept values. A comparison of δ2H and δ18O correlation equations with temperature during precipitation events showed a trend of decreasing slopes and intercepts with increasing temperature. Our data suggest that this is caused by incorporation of moisture derived from evaporation from water bodies and soils along the storm paths and by secondary evaporation between the cloud base and the ground during precipitation events. These processes compromise the usefulness of d-excess values as an indicator for the meteorological conditions in the maritime source regions. The δ18O temperature dependence at Calgary was found to be 0.44‰°C1. The study shows that short-term sampling of individual precipitation events yields valuable information, which is not obtainable by the widely used monthly collection programs.

  17. Lead isotope ratios in six lake sediment cores from Japan Archipelago: Historical record of trans-boundary pollution sources.

    Science.gov (United States)

    Hosono, Takahiro; Alvarez, Kelly; Kuwae, Michinobu

    2016-07-15

    Sediment cores from six lakes situated from north to south on the Japanese Archipelago were collected during 2009-2010 to investigate the hypothesis that deposition of lead (Pb) was coming from East Asia (including China, South Korea and eastern part of Russia). Accumulation rates and ages of the lake sediment were estimated by the (210)Pb constant rate of supply model and (137)Cs inputs to reconstruct the historical trends of Pb accumulation. Cores from four lakes located in the north and central Japan, showed clear evidence of Pb pollution with a change in the (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in the recent sediment as compared to the deeper sediment. Among the six studied lakes, significant inputs of anthropogenic lead emissions were observed at Lake Mikazuki (north Hokkaido in north Japan), Lake Chokai (north of Honshu), and Lake Mikuriga (central part of Honshu). Pb isotopic comparison of collected core sediment and previously reported data for wet precipitation and aerosols from different Asian regions indicate that, before 1900, Pb accumulated in these three lakes was not affected by trans-boundary sources. Lake Mikazuki started to receive Pb emissions from Russia in early 1900s, and during the last two decades, this lake has been affected by trans-boundary Pb pollution from northern China. Lake Chokai has received Pb pollutant from northern China since early 1900s until 2009, whereas for the Lake Mikuriga the major Pb contaminant was transported from southern China during the past 100years. The results of our study demonstrate that Japan Archipelago has received trans-boundary Pb emissions from different parts of East Asian region depending on location, and the major source region has changed historically. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. A Record of the Eastern Tropical Pacific of Water Column Structure Reorganization during the Rapid Climate Changes of Marine Isotope Stage 3.

    Science.gov (United States)

    Hendy, I. L.

    2007-05-01

    Little is known about the details of paleoceanographic changes in the Eastern Tropical Pacific (ETP) during marine isotope stage 3. Here we present a high resolution record of climate change from core ME0005A 10JC (15.7°N; 95.3°E, 1040 m water depth) collected in the Gulf of Tehuantepec spanning 48 to 38 Ka. Planktonic and benthic stable isotope records have been generated alongside Corg, carbonate, δ15N and trace metal concentrations of bulk sediments. Seasonal intense wind forced upwelling produces high Corg flux in the Gulf. In winter, high atmospheric pressures in the Gulf of Mexico and low pressures in the ETP (associated with the ITCZ) create a strong pressure gradient generally blocked by high mountains along the isthmus. A gap near the Gulf of Tehuantepec allows air to spill over into the Pacific creating a hurricane force wind (the Tehuanos) that pushes water off the broad shelf, producing non-Ekman upwelling. Corg production increases from 48 to 38 Ka in association with increasing nitrate utilization as indicated by increasing δ15N values. Conservative trace metals increase relative to non-conservative between 45 and 43 Ka simultaneously with shift to more positive benthic δ13C, while non-conservative (nutrient- like) metals increase after 43 Ka. A prominent short ~1‰ negative shift in benthic δ18O occurs at 44.5 Ka with a 0.5‰ positive step occurring at 43.5 Ka. Globigerina ruber records δ18O values of ~-1‰ between 46 and 45 Ka, decreasing by ~1‰ at 45 Ka, while δ13C values vary between 0 and 1‰. Globigerina bulloides records δ18O values of ~0.5‰ and δ13C of 1‰ between 46 and 45 Ka, but records δ18O values of ~-1‰ and δ13C of -1‰ between 44 and 42 Ka. G. bulloides is associated with winter upwelling in the region, while G. ruber is a surface dweller associated with the Costa Rica Current that enters the Gulf in summer. Neogloboquadrina dutertrei and Globorotalia menardii generally record δ18O values of 0.5 to 0‰ and δ13

  19. Mid- to late Holocene climate-driven regime shifts inferred from diatom, ostracod and stable isotope records from Lake Son Kol (Central Tian Shan, Kyrgyzstan)

    Science.gov (United States)

    Schwarz, Anja; Turner, Falko; Lauterbach, Stefan; Plessen, Birgit; Krahn, Kim J.; Glodniok, Sven; Mischke, Steffen; Stebich, Martina; Witt, Roman; Mingram, Jens; Schwalb, Antje

    2017-12-01

    Arid Central Asia represents a key region for understanding climate variability and interactions in the Northern Hemisphere. Patterns and mechanisms of Holocene climate change in arid Central Asia are, however, only partially understood. Multi-proxy data combining diatom, ostracod, sedimentological, geochemical and stable isotope analyses from a ca. 6000-year-old lake sediment core from Son Kol (Central Kyrgyzstan) show distinct and repeated changes in species assemblages. Diatom- and ostracod-inferred conductivity shifts between meso-euhaline and freshwater conditions suggest water balance and regime shifts. Organism-derived data are corroborated by stable isotope, mineralogical and geochemical records, underlining that Son Kol was affected by strong lake level fluctuations of several meters. The δ13Ccarb/δ18Ocarb correlation shows repeated switchovers from a closed to an open lake system. From 6000 to 3800 and 3250 to 1950 cal. yr BP, Son Kol was a closed basin lake with higher conductivities, increased nutrient availability and a water level located below the modern outflow. Son Kol became again a hydrologically open lake at 3800 and 1950 cal. yr BP. Comparisons to other local and regional paleoclimate records indicate that these regime shifts were largely controlled by changing intensity and position of the Westerlies and the Siberian Anticyclone that triggered changes in the amount of winter precipitation. A strong influence of the Westerlies ca. 5000-4400, 3800-3250 and since 1950 cal. yr BP enhanced the amount of precipitation during spring, autumn and winter, whereas cold and dry winters prevailed during phases with a strong Siberian Anticyclone and southward shifted Westerlies at ca. 6000-5000, 4400-3800 and 3250-1950 cal. yr BP. Similarities between variations in winter precipitation at Son Kol and records of the predominant NAO-mode further suggest a teleconnection between wet (dry) winter climate in Central Asia and a positive (negative) NAO

  20. Multiproxy Holocene paleoclimate records from the southern Peruvian Andes - what new can we learn from the stable carbon isotope composition of high altitude organic matter deposits?

    Science.gov (United States)

    Skrzypek, Grzegorz; Engel, Zbyněk

    2015-04-01

    Interpretation of the Central Andean paleoclimate over the last millennia still represents a research challenge demanding deeper studies [1,2]. Several high-resolution paleoclimate proxies for the last 10,000 years have been developed for the northern hemisphere. However, similar proxies are very limited for South America, particularly for high altitudes where, for example, tree-ring chronologies are not available and instrumental records are very limited. Consequently, our knowledge of high altitude climate changes in arid regions of the Peruvian Andes mainly relies on ice-core and lake deposit studies. In our study, we used a new alternative proxy for interpretation of palaeoclimate conditions based on a peat core taken from the Carhuasanta Valley at the foot of Nevado Mismi in the southern Peruvian Andes (15° 30'S, 71° 43'W, 4809m a.s.l.). The stable carbon isotope composition (δ13C) of Distichia peat reflects mainly the relative variation of the mean air temperature during subsequent growing seasons [3], and allows reconstructions of palaeotemperature changes. In contrast, peat organic carbon concentration (C % wt) records mainly wetness in the valley, directly corresponding to the changes in runoff in the upper part of the catchment. The most prominent climate changes recorded in the peat over last 4ka occurred between 3040 and 2750 cal. yrs BP. The initial warming turned to a very rapid cooling to temperatures at least 2° C lower than the mean for the Late Holocene. Initially drier conditions within this event turned to a short wet phase after 2780 cal. yrs BP, when the temperature increased again. This event coincides with significant changes in peat and ice core records in the Central Andes that match the timing of the global climate event around 2.8 cal. ka BP. Climatic conditions in the study area became relatively dry and stable after the event for about 800 years. Highly variable temperatures and humidity prevailed during the last 2000 years, when

  1. Using stable isotope analysis to determine the contribution of naturally occurring pond biota and supplementary feed to the diet of farmed Australian freshwater crayfish, redclaw (Cherax quadricarinatus

    Directory of Open Access Journals (Sweden)

    Melissa K. Joyce

    2015-12-01

    Full Text Available Abstract Nutritional requirements of redclaw (Cherax quadricarinatus farmed in Australia are poorly understood and little is known on what is actively being consumed in semi-intensive pond culture. In this study the isotopic signatures of δ13C and δ15N of potential food sources were analysed with a multi-source mixing model to determine the extent of their contribution to the diet of farmed redclaw. Four commercial redclaw farms in North Queensland, Australia (Mareeba, Biboorha, Wondecla and Topaz were sampled for naturally occurring pond organisms and commonly used supplemental feed such as raw corn, soybean, lupin, commercial redclaw, and chicken feed. Both naturally occurring pond biota and supplemental feed contribute to the tissue composition of redclaw to some degree. However, the contribution varies with the type of feed and availability of natural sources, for example plant material at Topaz Farm was a greater contributor with 43.9 ± 19.5 % compared to supplementary sources raw corn 8.20 ± 3.10 and lupin 1.60 ± 1.70 %. Moreover, some supplemental feeds provided a direct nutrient source for primary pond productivity; contribution of the redclaw pellet to zoo- and phytoplankton at Wondecla Farm was 83.1 ± 6.50 and 50.0 ± 9.50 %, respectively, with similarly high values for chicken feed at Biboorha Farm of 72.6 ± 4.70 and 83.4 ± 6.90 %. The cost effectiveness of such feeds needs to be questioned if these are not being consumed and utilised directly. Providing a species-specific formulated feed with improved water stability would enhance production reliability and facilitate growth within the industry.

  2. Centennial-scale vegetation dynamics and climate variability in SE Europe during Marine Isotope Stage 11 based on a pollen record from Lake Ohrid

    Science.gov (United States)

    Kousis, Ilias; Koutsodendris, Andreas; Peyron, Odile; Leicher, Niklas; Francke, Alexander; Wagner, Bernd; Giaccio, Biagio; Knipping, Maria; Pross, Jörg

    2018-06-01

    To better understand climate variability during Marine Isotope Stage (MIS) 11, we here present a new, centennial-scale-resolution pollen record from Lake Ohrid (Balkan Peninsula) derived from sediment cores retrieved during an International Continental Scientific Drilling Program (ICDP) campaign. Our palynological data, augmented by quantitative pollen-based climate reconstructions, provide insight into the vegetation dynamics and thus also climate variability in SE Europe during one of the best orbital analogues for the Holocene. Comparison of our palynological results with other proxy data from Lake Ohrid as well as with regional and global climate records shows that the vegetation in SE Europe responded sensitively both to long- and short-term climate change during MIS 11. The chronology of our palynological record is based on orbital tuning, and is further supported by the detection of a new tephra from the Vico volcano, central Italy, dated to 410 ± 2 ka. Our study indicates that MIS 11c (∼424-398 ka) was the warmest interval of MIS 11. The younger part of the interglacial (i.e., MIS 11b-11a; ∼398-367 ka) exhibits a gradual cooling trend passing over into MIS 10. It is characterized by considerable millennial-scale variability as inferred by six abrupt forest-contraction events. Interestingly, the first forest contraction occurred during full interglacial conditions of MIS 11c; this event lasted for ∼1.7 kyrs (406.2-404.5 ka) and was characterized by substantial reductions in winter temperature and annual precipitation. Most notably, it occurred ∼7 ka before the end of MIS 11c and ∼15 ka before the first strong ice-rafted debris event in the North Atlantic. Our findings suggest that millennial-scale climate variability during MIS 11 was established in Southern Europe already during MIS 11c, which is earlier than in the North Atlantic where it is registered only from MIS 11b onwards.

  3. 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.

  4. Neoarchean metamorphism recorded in high-precision Sm-Nd isotope systematics of garnets from the Jack Hills (Western Australia)

    Science.gov (United States)

    Eccles, K. A.; Baxter, E. F.; Mojzsis, S. J.; Marschall, H.; Williams, M. L.; Jercinovic, M. J.

    2013-12-01

    Studies of metasedimentary rocks from the Jack Hills, which host Earth's oldest known detrital minerals, have focused on zircon and occasionally monazite or xenotime, but no attention has been directed toward one of the most common mineral markers of metamorphism: garnet. Garnet can provide a record of the post-depositional, prograde metamorphic history of Archean metasedimentary rocks. Additionally, the use of a newly developed detrital garnet dating technique [1,2] may reveal information about pre-depositional metamorphism that could address lingering questions about the nature and timing of Earth's earliest tectonometamorphic events. Here we investigate garnet from the Jack Hills metasedimentary rocks to test whether they record in situ metamorphism or are a detrital relict of even older metamorphic events. We identified garnet in two bulk quartz-pebble conglomerate samples collected from the 'discovery' outcrop at Eranondoo Hill in the Jack Hills of Western Australia. Electron microprobe analyses of polished grains and SEM measurements of unpolished grain surfaces are consistent, revealing garnet composition indicative of a single generation/population of predominantly almandine-spessartine solid solution (~10-35% mole fraction spessartine). Compositional maps of garnet grains reveal little zoning and no discontinuities, most consistent with a single growth event. Dating Jack Hills' garnet via the Sm-Nd system is possible due to continued development of small sample analysis techniques, including running NdO+ TIMS analyses with Ta2O5 activator [3] permitting Ma for two point isochrons between clean garnet (Sm/Nd ≥ 1.0) and their leached inclusion populations [2]. Four grouped garnet grain separates from one sample yield preliminary dates of 2703.6×6.0Ma, 2612.4×6.0Ma, 2605.0×5.5Ma, and 2567.3×8.3Ma, while the second sample yielded a date of 2579.6×4.6 Ma (2σ). Compositional and geochronologic data indicate likely in situ garnet growth during a late

  5. Astronomically forced paleoclimate change from middle Eocene to early Oligocene: continental conditions in central China compared with the global marine isotope record

    Science.gov (United States)

    Huang, C.; Hinnov, L. A.

    2010-12-01

    The early Eocene climatic optimum ended with a long interval of global cooling that began in the early Middle Eocene and ended at the Eocene-Oligocene transition. During this long-term cooling, a series of short-term warming reversals occurred in the marine realm. Here, we investigate corresponding continental climate conditions as revealed in the Qianjiang Formation of the Jianghan Basin in central China, which consists of more than 4000 m of saline lake sediments. The Qianjiang Formation includes, in its deepest sections, a halite-rich rhythmic sediment succession with dark mudstone, brownish-white siltstone and sandstone, and greyish-white halite. Alternating fresh water (humid/cool)—saline water (dry/hot) deposits reflect climate cycles driven by orbital forcing. High-resolution gamma ray (GR) logging from the basin center captures these pronounced lithological rhythms throughout the formation. Several halite-rich intervals are interpreted as short-term warming events within the middle Eocene to early Oligocene, and could be expressions of coeval warming events in the global marine oxygen isotope record, for example, the middle Eocene climate optimum (MECO) event around 41 Ma. The Eocene-Oligocene boundary is distinguished by a radical change from halite-rich to clastic sediments, indicating a dramatic climate change from warm to cool conditions. Power spectral analysis of the GR series indicates strong short (~100 kyr) eccentricity cycling during the warm/hot episodes. Amplitude modulation of the short eccentricity in the GR series occurs with a strong 405 kyr periodicity. This cycling is calibrated to the La2004 orbital eccentricity model. A climate reversal occurs at 36.5 Ma within the long-term marine cooling trend following MECO, which is reflected also in the Qianjiang GR series, with the latter indicating several brief warm/dry reversals within the trend. A ~2.6 Myr halite-rich warm interval occurs in the latest Eocene in the continental record; both

  6. Lake oxygen isotopes as recorders of North American Rocky Mountain hydroclimate: Holocene patterns and variability at multi-decadal to millennial time scales

    Science.gov (United States)

    Anderson, Lesleigh; Max Berkelhammer,; Barron, John A.; Steinman, Byron A.; Finney, Bruce P.; Abbott, Mark B.

    2016-01-01

    Lake sediment oxygen isotope records (calcium carbonate-δ18O) in the western North American Cordillera developed during the past decade provide substantial evidence of Pacific ocean–atmosphere forcing of hydroclimatic variability during the Holocene. Here we present an overview of 18 lake sediment δ18O records along with a new compilation of lake water δ18O and δ2H that are used to characterize lake sediment sensitivity to precipitation-δ18O in contrast to fractionation by evaporation. Of the 18 records, 14 have substantial sensitivity to evaporation. Two records reflect precipitation-δ18O since the middle Holocene, Jellybean and Bison Lakes, and are geographically positioned in the northern and southern regions of the study area. Their comparative analysis indicates a sequence of time-varying north–south precipitation-δ18O patterns that is evidence for a highly non-stationary influence by Pacific ocean–atmosphere processes on the hydroclimate of western North America. These observations are discussed within the context of previous research on North Pacific precipitation-δ18O based on empirical and modeling methods. The Jellybean and Bison Lake records indicate that a prominent precipitation-δ18O dipole (enriched-north and depleted-south) was sustained between ~ 3.5 and 1.5 ka, which contrasts with earlier Holocene patterns, and appears to indicate the onset of a dominant tropical control on North Pacific ocean–atmosphere dynamics. This remains the state of the system today. Higher frequency reversals of the north–south precipitation-δ18O dipole between ~ 2.5 and 1.5 ka, and during the Medieval Climate Anomaly and the Little Ice Age, also suggest more varieties of Pacific ocean–atmosphere modes than a single Pacific Decadal Oscillation (PDO) type analogue. Results indicate that further investigation of precipitation-δ18O patterns on short (observational) and long (Holocene) time scales is needed to improve our understanding of the

  7. Lake oxygen isotopes as recorders of North American Rocky Mountain hydroclimate: Holocene patterns and variability at multi-decadal to millennial time scales

    Science.gov (United States)

    Anderson, Lesleigh; Berkelhammer, Max; Barron, John A.; Steinman, Byron A.; Finney, Bruce P.; Abbott, Mark B.

    2016-02-01

    Lake sediment oxygen isotope records (calcium carbonate-δ18O) in the western North American Cordillera developed during the past decade provide substantial evidence of Pacific ocean-atmosphere forcing of hydroclimatic variability during the Holocene. Here we present an overview of 18 lake sediment δ18O records along with a new compilation of lake water δ18O and δ2H that are used to characterize lake sediment sensitivity to precipitation-δ18O in contrast to fractionation by evaporation. Of the 18 records, 14 have substantial sensitivity to evaporation. Two records reflect precipitation-δ18O since the middle Holocene, Jellybean and Bison Lakes, and are geographically positioned in the northern and southern regions of the study area. Their comparative analysis indicates a sequence of time-varying north-south precipitation-δ18O patterns that is evidence for a highly non-stationary influence by Pacific ocean-atmosphere processes on the hydroclimate of western North America. These observations are discussed within the context of previous research on North Pacific precipitation-δ18O based on empirical and modeling methods. The Jellybean and Bison Lake records indicate that a prominent precipitation-δ18O dipole (enriched-north and depleted-south) was sustained between ~ 3.5 and 1.5 ka, which contrasts with earlier Holocene patterns, and appears to indicate the onset of a dominant tropical control on North Pacific ocean-atmosphere dynamics. This remains the state of the system today. Higher frequency reversals of the north-south precipitation-δ18O dipole between ~ 2.5 and 1.5 ka, and during the Medieval Climate Anomaly and the Little Ice Age, also suggest more varieties of Pacific ocean-atmosphere modes than a single Pacific Decadal Oscillation (PDO) type analogue. Results indicate that further investigation of precipitation-δ18O patterns on short (observational) and long (Holocene) time scales is needed to improve our understanding of the processes that drive

  8. Magma Mixing, Mingling and Its Accompanying Isotopic and Elemental Partitioning: Records from Titanites in Guojialing-type Granodiorites and Dioritic Enclaves, Jiaodong, North China

    Science.gov (United States)

    Jiang, P.; Yang, K. F.; Fan, H. R.; Liu, X.

    2016-12-01

    The grain-scale textural and in-situ compositional analyses on accessory minerals (such as titanite, rutile, apatite, monazite, etc.) have recently been a hot topic for geologists, through which a detailed information on magmatic, metamorphic or hydrothermal process can be extracted. As an attempt to unravel the petrogenesis of Early Cretaceous Guojialing-type granodiorites and their bearing dioritic enclaves, we accomplished an integrated geochronological and geochemical study on titanites within these rocks. Three types of titanites, with distinguishable textural and geochemical features, are identified. G-type titanites (from granodiorites) and E-type-I titanites (from plagioclase-rich dioritic enclaves) yield identical U-Pb age of 130 Ma, but reveal distinct back-scattered electron (BSE) zonings. G-type titanites are characterized by oscillatory zonings whereas E-type-I titanites are marked by core-mantle-rim zonings, exhibiting drastic but contrary variation trends for several key elements (such as LREEs, Zr, Hf and F) among their transition BSE zones. These two types of titanites are interpreted to crystallize coevally, and record a notable temperature and compositional change of two corresponding melts, as a response to magma mixing. E-type-II titanites (from plagioclase-poor dioritic enclaves) yield a relatively younger U-Pb age at 128 Ma, and show typical interstitial growth with narrower and lower range of Zr, total REEs contents, but higher F content and Nb/Ta ratios. Such titanites are perceived to record late-stage mingling, during which F-rich and REE-poor hybrid granodioritic magma squeezed into the incompletely consolidated dioritic enclaves with accompanying fluid-rock interaction. Unlike the dramatic elemental changes in these differentiated titanites, in-situ Nd isotopic compositions are relatively homogeneous, which in our view is a good sign of showing that isotopic equilibrium among two magma systems was more easily reached compared to

  9. Stable isotope record of Eemian seasonal temperature from MIS 5e tufa stromatolite; Somme Basin, Northern France

    Science.gov (United States)

    Dabkowski, J.; Andrews, J.; Antoine, P.; Marca-Bell, A.

    2013-03-01

    In many modern to sub-fossil deposits tufa formations, very well crystallised deposits called stromatolites are preserved. These are often strongly laminated deposits, the laminae linked to seasonal climatic and environmental variations. Where found in fossil tufas such deposits have huge potential as high resolution archives of Pleistocene climate. One of the first investigations of this type has been performed on a 2.5 cm-radius stromatolite from the Eemian sequence of Caours (Somme Basin, Northern France), where precise observations in thin section have been combined with intra-lamina δ18O and δ13C analyses. Independent interpretations of petrographical and geochemical data are strongly coherent and demonstrate a clear seasonal signal. Moreover, as δ18O is temperature dependent, we have quantified likely maximum water temperature variations between summer and winter at Caours. A small mismatch between the δ18O derived temperature values and the typical modern range is observed, which may reflect a real difference between modern and Eemian temperature seasonality. This study supports previous investigations performed on a laminated tufa from central Greece and clearly confirms the potential of tufa stromatolites as records of seasonal climatic information and for the quantification of riverine water temperature variations.

  10. Anthropogenic contributions to atmospheric Hg, Pb and As accumulation recorded by peat cores from southern Greenland and Denmark dated using the 14C "bomb pulse curve"

    Science.gov (United States)

    Shotyk, W.; Goodsite, M. E.; Roos-Barraclough, F.; Frei, R.; Heinemeier, J.; Asmund, G.; Lohse, C.; Hansen, T. S.

    2003-11-01

    Mercury concentrations are clearly elevated in the surface and sub-surface layers of peat cores collected from a minerotrophic ("groundwater-fed") fen in southern Greenland (GL) and an ombrotrophic ("rainwater-fed") bog in Denmark (DK). Using 14C to precisely date samples since ca. AD 1950 using the "atmospheric bomb pulse," the chronology of Hg accumulation in GL is remarkably similar to the bog in DK where Hg was supplied only by atmospheric deposition: this suggests not only that Hg has been supplied to the surface layers of the minerotrophic core (GL) primarily by atmospheric inputs, but also that the peat cores have preserved a consistent record of the changing rates of atmospheric Hg accumulation. The lowest Hg fluxes in the GL core (0.3 to 0.5 μg/m 2/yr) were found in peats dating from AD 550 to AD 975, compared to the maximum of 164 μg/m 2/yr in AD 1953. Atmospheric Hg accumulation rates have since declined, with the value for 1995 (14 μg/m 2/yr) comparable to the value for 1995 obtained by published studies of atmospheric transport modelling (12 μg/m 2/yr). The greatest rates of atmospheric Hg accumulation in the DK core are also found in the sample dating from AD 1953 and are comparable in magnitude (184 μg/m 2/yr) to the GL core; again, the fluxes have since gone into strong decline. The accumulation rates recorded by the peat core for AD 1994 (14 μg/m 2/yr) are also comparable to the value for 1995 obtained by atmospheric transport modelling (18 μg/m 2/yr). Comparing the Pb/Ti and As/Ti ratios of the DK samples with the corresponding crustal ratios (or "natural background values" for preanthropogenic peat) shows that the samples dating from 1953 also contain the maximum concentration of "excess" Pb and As. The synchroneity of the enrichments of all three elements (Hg, Pb, and As) suggests a common source, with coal-burning the most likely candidate. Independent support for this interpretation was obtained from the Pb isotope data ( 206Pb/ 207Pb

  11. The contribution of audio recording using portable digital voice recorders to the development of reflective practice with trainee teachers in a Further Education setting

    OpenAIRE

    Knill, Marta; Samuels, Mary

    2011-01-01

    Developing reflective skills and habits during initial teacher education and progressing to deeper and more critical reflection are challenges for trainee teachers. This small-scale action research study investigates how two structured tasks using Digital Voice Recorders (DVRs) initiated, sustained and improved reflection and reflective practice. Trainee teachers reported benefits in increased understanding of reflection, development of reflective skills, deepening of reflection and improveme...

  12. Caesium and Plutonium Isotopes as Tracers of Various Events in Sediment Records in the Bay of Toulon (Northwestern Mediterranean Sea)

    Energy Technology Data Exchange (ETDEWEB)

    Duffa, C.; Arnaud, M.; Charmasson, S.; Thebault, H. [Institut de Radioprotection et de Surete Nucleaire, DEI/SESURE/LERCM, La Seyne sur Mer (France)

    2013-07-15

    Located along the French Mediterranean coast, the Toulon bay has a specific configuration with two basins. The shallow one is a semi-enclosed basin (Petite Rade) with complex hydrodynamic conditions that contribute to fine sedimentation. The open sea basin, separated from the first one by a long sea wall, receives different anthropogenic inputs. Surface and core sediment sampling cruises took place in 2001 and 2008, in order to study radionuclide spatial dispersion and sediment accumulation. {sup 137}Cs values are statistically higher in the 'Petite Rade' than in the open basin. {sup 239+240}Pu levels range from 0.7 to 2.6 Bq/kg dry weight in surface sediments, up to 6 times higher than elsewhere in Mediterranean coastal areas not influenced by riverine inputs. Plutonium activity ratios ({sup 238}Pu/{sup 239+240}Pu and {sup 239}Pu/{sup 240}Pu) labelled atmospheric nuclear weapon testing. Regarding the long cores, the highest plutonium activities, measured by alpha counting and ICP-MS, concern the first ten centimetres with a maximum value of 3.5 Bq/kg dry weight in {sup 239+240}Pu. (author)

  13. Contribution of local thyroxine monodeiodination to intracellular 3,5, 3'-triiodothyronine in several tissues of hyperthyroid rats at isotopic equilibrium

    International Nuclear Information System (INIS)

    van Doorn, J.; van der Heide, D.; Roelfsema, F.

    1984-01-01

    The local conversion of T4 as a source of intracellular T3 in several organs of both hypothyroid and euthyroid rats has recently been recognized to be an important phenomenon. In the present study the source and quantity of T3 in various peripheral tissues of hyperthyroid rats were investigated. Athyreotic rats received a continuous iv infusion of T4 over a prolonged period in order to attain hyperthyroid conditions. At the same time, the animals also received a continuous iv infusion of [ 125 I]T4 and [ 131 I]T3 until isotopic equilibrium was achieved. After the animals were bled and perfused, the source and quantity of T3 in various tissue homogenates and subcellular preparations of liver, kidney, and the anterior pituitary gland were analyzed. In spite of the elevated plasma T3 and T4 levels, the concentration of T3 in the cerebral cortex and cerebellum was within the normal range. The contribution of T3 derived from local T4 to T3 conversion [Lc T3(T4)] was rather low in both parts of the brain when compared with values previously determined for euthyroid rats. Whereas previous studies revealed that Lc T3(T4) contributes significantly to the T3 in the pituitary glands of both hypothyroid and euthyroid rats, this was not the case for the hyperthyroid animals; virtually all T3 was derived from plasma. It was found that the T3 in muscle was derived exclusively from plasma. Both the liver and kidney showed high concentrations of T3. Whereas Lc T3(T4) was the main source of T3 in the liver, it contributed only a minor fraction of the total T3 content in the kidney

  14. Stable oxygen isotope and flux partitioning demonstrates understory of an oak savanna contributes up to half of ecosystem carbon and water exchange

    Directory of Open Access Journals (Sweden)

    Maren eDubbert

    2014-10-01

    Full Text Available Semi-arid ecosystems contribute about 40% to global net primary production (GPP even though water is a major factor limiting carbon uptake. Evapotranspiration (ET accounts for up to 95% of the water loss and in addition, vegetation can also mitigate drought effects by altering soil water distribution. Hence, partitioning of carbon and water fluxes between the soil and vegetation components is crucial to gain mechanistic understanding of vegetation effects on carbon and water cycling. However, the possible impact of herbaceous vegetation in savanna type ecosystems is often overlooked. Therefore, we aimed at quantifying understory vegetation effects on the water balance and productivity of a Mediterranean oak savanna. ET and net ecosystem CO2 exchange (NEE were partitioned based on flux and stable oxygen isotope measurements and also rain infiltration was estimated.The understory vegetation contributed importantly to total ecosystem ET and GPP with a maximum of 43% and 51%, respectively. It reached water-use efficiencies (WUE; ratio of carbon gain by water loss similar to cork-oak trees. The understory vegetation inhibited soil evaporation (E and, although E was large during wet periods, it did not diminish WUE during water-limited times. The understory strongly increased soil water infiltration, specifically following major rain events. At the same time, the understory itself was vulnerable to drought, which led to an earlier senescence of the understory growing under trees as compared to open areas, due to competition for water. Thus, beneficial understory effects are dominant and contribute to the resilience of this ecosystem. At the same time the vulnerability of the understory to drought suggests that future climate change scenarios for the Mediterranean basin threaten understory development. This in turn will very likely diminish beneficial understory effects like infiltration and ground water recharge and therefore ecosystem resilience to

  15. Contribution of local thyroxine monodeiodination to intracellular 3,5, 3'-triiodothyronine in several tissues of hyperthyroid rats at isotopic equilibrium

    Energy Technology Data Exchange (ETDEWEB)

    van Doorn, J.; van der Heide, D.; Roelfsema, F.

    1984-07-01

    The local conversion of T4 as a source of intracellular T3 in several organs of both hypothyroid and euthyroid rats has recently been recognized to be an important phenomenon. In the present study the source and quantity of T3 in various peripheral tissues of hyperthyroid rats were investigated. Athyreotic rats received a continuous iv infusion of T4 over a prolonged period in order to attain hyperthyroid conditions. At the same time, the animals also received a continuous iv infusion of (/sup 125/I)T4 and (/sup 131/I)T3 until isotopic equilibrium was achieved. After the animals were bled and perfused, the source and quantity of T3 in various tissue homogenates and subcellular preparations of liver, kidney, and the anterior pituitary gland were analyzed. In spite of the elevated plasma T3 and T4 levels, the concentration of T3 in the cerebral cortex and cerebellum was within the normal range. The contribution of T3 derived from local T4 to T3 conversion (Lc T3(T4)) was rather low in both parts of the brain when compared with values previously determined for euthyroid rats. Whereas previous studies revealed that Lc T3(T4) contributes significantly to the T3 in the pituitary glands of both hypothyroid and euthyroid rats, this was not the case for the hyperthyroid animals; virtually all T3 was derived from plasma. It was found that the T3 in muscle was derived exclusively from plasma. Both the liver and kidney showed high concentrations of T3. Whereas Lc T3(T4) was the main source of T3 in the liver, it contributed only a minor fraction of the total T3 content in the kidney.

  16. Monsoon Variability In The Western Arabian Sea During Last 10,000 Years BP: A Planktic Foraminiferal Abundances And It's Stable Isotope Records

    Science.gov (United States)

    Singh, A. K.; Tiwari, M.; Sinha, D. K.; Ramesh, R.

    2007-12-01

    : The western Arabian Sea responds to the southwest monsoon winds by upwelling colder and nutrient rich waters from the deeper layers, causing a reduction in the sea surface temperature and enhanced biological productivity. A number of paleoclimatic studies have been carried out in this region to elucidate past monsoon variability (Sirocco et al., 1993; Gupta et al, 2003; Tiwari, 2005; Saher et.al.; 2007). Globigerina bulloides, a planktic foraminiferal species normally inhabiting surface ocean waters in temperate latitudes ( Be and Tolderlund , 1977) also becomes abundant at tropical latitudes upwelling occurs, and in these cases its abundance can exceed considerably. The conspicuous fluctuation in the abundance of Gg.bulloides during upwelling and non upwelling intervals is established through several studies ( Thiede and Junger, 1980, Gupta et al, 2003) This robust relation has been used as a proxy for wind velocity at several different times in the past in the Arabian Sea (Anderson et.al., 2002). A significant result from some of these centennially resolved Holocene records is declining abundance of Globigerina bulloides which is paralleled by reduced insolation record and this has been inferred as declining strength of Asian Monsoon. We are presenting here the data from the core SS4018 from near the Gulf of Aden, Western Arabian Sea taken at a water depth of 2830 m, precisely dated by the radiocarbon method using Accelerator Mass Spectrometry on planktonic foraminiferal separates. We have carried out the planktic foraminiferal census counts for each sample to know the relative abundance of key species. In addition to this, we have also employed multi- proxy approach such as oxygen and carbon isotopes of planktic foraminiferal tests, TOC, CaCO3 (%) to strengthen our interpretation and also to understand the relationships amongst the proxies themselves. Abundance of the key planktic foraminiferal species and other proxy records reveal at least 3 major climatic

  17. The Isotopologue Record of Repeat Vital Effect Offenders: Tracking (Dis)equilibrium Effects in Sea Urchins and Nannofossil Using Clumped Isotopes

    Science.gov (United States)

    John, C. M.; Davies, A.; Drury, A. J.

    2016-12-01

    Vital effects vary between species and affect various isotopic systems in unequal proportion. The magnitude of the response of different isotopic systems might thus be key in understanding biologically-mediated disequilibrium, especially in groups that show a tendency to be "repeat offenders" with regards to vital effects. Here we present carbon, oxygen, and clumped isotope data from echinoderm calcite and nannofossil ooze, both of which exhibit strong vital effects in bulk isotopes. Our study is the first to investigate the clumped isotope (dis)equilibrium of echinoids. Results from two echinoids, three marine gastropods and a bivalve mollusk from modern beach deposits of Bali, Indonesia, highlight a significant offset in clumped isotopes of a regular echinoid test from expected values, interpreted as evidence of a similar "vital effect" as observed in surface corals. This is in contrast to the test of an irregular "sand dollar" echinoid, with clumped isotope values within error of expected sea surface temperature. Furthermore, data on the inter-skeletal variability in the clumped isotopic composition of two regular echinoid species shows that the spines of the echinoids are in equilibrium with seawater with respect to clumped isotopes, but the test is not. For the nannofossil material, no clumped isotope vital effects are observed, consistent with previously published studies but at odds with strong vital effects in carbon and oxygen isotopes, often correlated with cell-size. In addition, we reveal that the <63 micron fraction of deep-sea ooze could constitute useful material for clumped isotope studies. An intriguing result of our study is that vital effects are mostly absent in clumped isotopes, even in phylums known for important isotopic effects. It remains to be explained why some parts of the echinoids show clear vital effects, notably enrichment in clumped isotopes of urchin tests. Mechanisms that could explain this include pH effects during calcification

  18. The use of the 15N isotope dilution technique to estimate the contribution of associated biological nitrogen fixation to the nitrogen nutrition of Paspalum notatum cv. batatais

    International Nuclear Information System (INIS)

    Boddey, R.M.; Doebereiner, Johanna

    1983-01-01

    This paper reports the results of a field experiment to investigate the use of the 15 N-dilution technique to measure the contribution of biological N 2 fixation to the N nutrition of the batatais cultivar of Paspalum notatum. The pensacola cultivar of this grass supports little associated N 2 fixation as evidenced by the low associated C 2 H 2 reduction activity and was thus used as a nonfixing control plant. The grasses were grown in 60-cm diameter concrete cylinders sunk into the soil, and the effects of four different addition rates of labelled nitrogen (NH 4 ) 2 SO 4 , were investigated. The data from seven harvests clearly demonstrated that there was a significant input of plant associated N 2 fixation to the nutrition of the batatais cultivar amounting to approximately 20 kg N ha -1 year -1 . Problems associated with the conduct of such isotope dilution experiments are discussed including the importance of using nonfixing control plants of similar growth habit, the advantages and disadvantages of growing the plants in cylinders as opposed to field plots, and the various methods of application of labelled N fertilizer

  19. An ocean–ice coupled response during the last glacial: a view from a marine isotopic stage 3 record south of the Faeroe Shetland Gateway

    Directory of Open Access Journals (Sweden)

    J. Zumaque

    2012-12-01

    Full Text Available The rapid climatic variability characterising the Marine Isotopic Stage (MIS 3 (~60–30 cal ka BP provides key issues to understand the atmosphere–ocean–cryosphere dynamics. Here we investigate the response of sea-surface paleoenvironments to the MIS3 climatic variability through the study of a high resolution oceanic sedimentological archive (core MD99-2281, 60°21' N; 09°27' W; 1197 m water depth, retrieved during the MD114-IMAGES (International Marine Global Change Study cruise from the southern part of the Faeroe Bank. This sector was under the proximal influence of European ice sheets (Fennoscandian Ice Sheet to the East, British Irish Ice Sheet to the South during the last glacial and thus probably responded to the MIS3 pulsed climatic changes.

    We conducted a multi-proxy analysis of core MD99-2281, including magnetic properties, x-ray fluorescence measurements, characterisation of the coarse (>150 μm lithic fraction (grain concentration and the analysis of selected biogenic proxies (assemblages and stable isotope ratio of calcareous planktonic foraminifera, dinoflagellate cyst – e.g. dinocyst – assemblages. Results presented here are focussed on the dinocyst response, this proxy providing the reconstruction of past sea-surface hydrological conditions, qualitatively as well as quantitatively (e.g. transfer function sensu lato. Our study documents a very coherent and sensitive oceanic response to the MIS3 rapid climatic variability: strong fluctuations, matching those of stadial/interstadial climatic oscillations as depicted by Greenland ice cores, are recorded in the MD99-2281 archive. Proxies of terrigeneous and detritical material suggest increases in continental advection during Greenland Stadials (including Heinrich events, the latter corresponding also to southward migrations of polar waters. At the opposite, milder sea-surface conditions seem to develop during Greenland Interstadials. After 30 ka

  20. Contribution of the isotopic study of nitrogen to the knowledge of the pollution of underground aquifers by nitrates, in agricultural environment (Brie, Beauce - France)

    International Nuclear Information System (INIS)

    Mariotti, A.; Ben Halima, A.; Berger, G.

    1976-01-01

    Isotope composition of nitrate nitrogen from aquifers in the highly cultivated areas from Brie and Beauce show three different nitrogen inputs: nitrate from organic matter in soils; nitrate from fertilizers; nitrate from domestic and animal wastes. The isotope composition of those stocks are different enough to trace their origin and establish material balances of nitrogen pollution [fr

  1. Intercontinental correlation of organic carbon and carbonate stable isotope records: evidence of climate and sea-evel change during the Turonian (Cretaceous)

    Czech Academy of Sciences Publication Activity Database

    Jarvis, I.; Trabucho-Alexandre, J.; Gröcke, D. R.; Uličný, David; Laurin, Jiří

    2015-01-01

    Roč. 1, č. 2 (2015), s. 53-90 ISSN 2055-4877 R&D Projects: GA ČR GAP210/10/1991; GA MŠk LH12041 Institutional support: RVO:67985530 Keywords : carbon isotopes * chemostratigraphy * climate change * Cretaceous * oxygen isotopes Subject RIV: DB - Geology ; Mineralogy

  2. Juvenile crust formation in the Zimbabwe Craton deduced from the O-Hf isotopic record of 3.8-3.1 Ga detrital zircons

    Science.gov (United States)

    Bolhar, Robert; Hofmann, Axel; Kemp, Anthony I. S.; Whitehouse, Martin J.; Wind, Sandra; Kamber, Balz S.

    2017-10-01

    Hafnium and oxygen isotopic compositions measured in-situ on U-Pb dated zircon from Archaean sedimentary successions belonging to the 2.9-2.8 Ga Belingwean/Bulawayan groups and previously undated Sebakwian Group are used to characterize the crustal evolution of the Zimbabwe Craton prior to 3.0 Ga. Microstructural and compositional criteria were used to minimize effects arising from Pb loss due to metamorphic overprinting and interaction with low-temperature fluids. 207Pb/206Pb age spectra (concordance >90%) reveal prominent peaks at 3.8, 3.6, 3.5, and 3.35 Ga, corresponding to documented geological events, both globally and within the Zimbabwe Craton. Zircon δ18O values from +4 to +10‰ point to both derivation from magmas in equilibrium with mantle oxygen and the incorporation of material that had previously interacted with water in near-surface environments. In εHf-time space, 3.8-3.6 Ga grains define an array consistent with reworking of a mafic reservoir (176Lu/177Hf ∼0.015) that separated from chondritic mantle at ∼3.9 Ga. Crustal domains formed after 3.6 Ga depict a more complex evolution, involving contribution from chondritic mantle sources and, to a lesser extent, reworking of pre-existing crust. Protracted remelting was not accompanied by significant mantle depletion prior to 3.35 Ga. This implies that early crust production in the Zimbabwe Craton did not cause complementary enriched and depleted reservoirs that were tapped by later magmas, possibly because the volume of crust extracted and stabilised was too small to influence (asthenospheric) mantle isotopic evolution. Growth of continental crust through pulsed emplacement of juvenile (chondritic mantle-derived) melts, into and onto the existing cratonic nucleus, however, involved formation of complementary depleted subcontinental lithospheric mantle since the early Archaean, indicative of strongly coupled evolutionary histories of both reservoirs, with limited evidence for recycling and lateral

  3. Combined oxygen- and carbon-isotope records through the Early Jurassic: multiple global events and two modes of carbon-cycle/temperature coupling

    DEFF Research Database (Denmark)

    Hesselbo, Stephen P.; Korte, Christoph

    2010-01-01

    , to the extent that meaningful comparisons between these events can begin to be made. Here we present new carbon and oxygen isotope data from mollusks (bivalves and belemnites) and brachiopods collected through the marine Early Jurassic succession of NE England, including the Sinemurian-Plienbachian boundary...... GSSP. All materials have been screened by chemical analysis and scanning electron microscopy to check for diagenetic alteration. Analysis of carbon isotopes from marine calcite is supplemented by analysis of carbon-isotope values from fossil wood collected through the same section. It is demonstrated...... that both long-term and short-term carbon-isotope shifts from the UK Early Jurassic represent global changes in carbon cycle balances. The Sinemurian-Pliensbachian boundary event is an event of global significance and shows several similarities to the Toarcian OAE (relative sea-level change, carbon-isotope...

  4. The Steady State Great Ape? Long Term Isotopic Records Reveal the Effects of Season, Social Rank and Reproductive Status on Bonobo Feeding Behavior

    Science.gov (United States)

    Oelze, Vicky M.; Douglas, Pamela Heidi; Stephens, Colleen R.; Surbeck, Martin; Behringer, Verena; Richards, Michael P.; Fruth, Barbara; Hohmann, Gottfried

    2016-01-01

    Dietary ecology of extant great apes is known to respond to environmental conditions such as climate and food availability, but also to vary depending on social status and life history characteristics. Bonobos (Pan paniscus) live under comparatively steady ecological conditions in the evergreen rainforests of the Congo Basin. Bonobos are an ideal species for investigating influences of sociodemographic and physiological factors, such as female reproductive status, on diet. We investigate the long term dietary pattern in wild but fully habituated bonobos by stable isotope analysis in hair and integrating a variety of long-term sociodemographic information obtained through observations. We analyzed carbon and nitrogen stable isotopes in 432 hair sections obtained from 101 non-invasively collected hair samples. These samples represented the dietary behavior of 23 adult bonobos from 2008 through 2010. By including isotope and crude protein data from plants we could establish an isotope baseline and interpret the results of several general linear mixed models using the predictors climate, sex, social rank, reproductive state of females, adult age and age of infants. We found that low canopy foliage is a useful isotopic tracer for tropical rainforest settings, and consumption of terrestrial herbs best explains the temporal isotope patterns we found in carbon isotope values of bonobo hair. Only the diet of male bonobos was affected by social rank, with lower nitrogen isotope values in low-ranking young males. Female isotope values mainly differed between different stages of reproduction (cycling, pregnancy, lactation). These isotopic differences appear to be related to changes in dietary preference during pregnancy (high protein diet) and lactation (high energy diet), which allow to compensate for different nutritional needs during maternal investment. PMID:27626279

  5. Improved source apportionment of PAHs and Pb by integrating Pb stable isotopes and positive matrix factorization application (PAHs): A historical record case study from the northern South China Sea.

    Science.gov (United States)

    Cai, Minggang; Lin, Yan; Chen, Meng; Yang, Weifeng; Du, Huihong; Xu, Ye; Cheng, Shayen; Xu, Fangjian; Hong, Jiajun; Chen, Mian; Ke, Hongwei

    2017-12-31

    To obtain the historical changes of pyrogenic sources, integrated source apportionment methods, which include PAH compositions, diagnostic ratios (DRs), Pb isotopic ratios, and positive matrix factorization (PMF) model, were developed and applied in sediments of the northern South China Sea. These methods provided a gradually clear picture of energy structural change. Spatially, Σ 15 PAH (11.3 to 95.5ng/g) and Pb (10.2 to 74.6μg/g) generally exhibited decreasing concentration gradient offshore; while the highest levels of PAHs and Pb were observed near the southern Taiwan Strait, which may be induced by accumulation of different fluvial input. Historical records of pollutants followed closely with the economic development of China, with fast growth of Σ 15 PAH and Pb occurring since the 1980s and 1990s, respectively. The phasing-out of leaded gasoline in China was captured with a sharp decrease of Pb after the mid-1990s. PAHs and Pb correlated well with TOC and clay content for core sediments, which was not observed for surface sediments. There was an up-core increase of high molecular PAH proportions. Coal and biomass burning were then qualitatively identified as the major sources of PAHs with DRs. Furthermore, shift toward less radiogenic signatures of Pb isotopic ratios after 1900 revealed the start and growing importance of industrial sources. Finally, a greater separation and quantification of various input was achieved by a three-factor PMF model, which made it clear that biomass burning, coal combustion, and vehicle emissions accounted for 40±20%, 41±13%, and 19±12% of PAHs through the core. Biomass and coal combustion acted as major sources before 2000, while contributions from vehicle emission soared thereafter. The integrated multi-methodologies here improved the source apportionment by reducing biases with a step-down and cross-validation perspective, which could be similarly applied to other aquatic systems. Copyright © 2017 Elsevier B.V. All

  6. Mars Atmospheric Escape Recorded by H, C and O Isotope Ratios in Carbon Dioxide and Water Measured by the Sam Tunable Laser Spectrometer on the Curiosity Rover

    Science.gov (United States)

    Webster, C. R.; Mahaffy, P. R.; Leshin, L. A.; Atreya, S. K.; Flesch, G. J.; Stern, J.; Christensen, L. E.; Vasavada, A. R.; Owen, T.; Niles, P. B.; hide

    2013-01-01

    Stable isotope ratios in C, H, N, O and S are powerful indicators of a wide variety of planetary geophysical processes that can identify origin, transport, temperature history, radiation exposure, atmospheric escape, environmental habitability and biological activity [2]. For Mars, measurements to date have indicated enrichment in all the heavier isotopes consistent with atmospheric escape processes, but with uncertainty too high to tie the results with the more precise isotopic ratios achieved from SNC meteoritic analyses. We will present results to date of H, C and O isotope ratios in CO2 and H2O made to high precision (few per mil) using the Tunable Laser Spectrometer (TLS) that is part of the Sample Analysis at Mars (SAM) instrument suite on MSL s Curiosity Rover.

  7. Fluvial influx and weathering history of the Himalayas since Last Glacial Maxima - Isotopic, sedimentological and magnetic records from the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Patil, S.K.; Suneethi, J.

    From temporal variations in stable isotopes, mineral magnetism, clay minerals and granulometric parameters from a sup(14) C dated core have been used to understand weathering history and influence of climate on the terrigenous fluxes into the Bay...

  8. Methodological validation of the isotopic analysis of fossil bones and contributions to the paleo-ecological reconstitutions of the Upper Paleolithic of south-west France

    International Nuclear Information System (INIS)

    Drucker, D.

    2001-04-01

    A methodology for investigating fossil bone collagen carbon and nitrogen isotopic signatures has been established in order to obtain palaeo-ecological informations. The archaeological, biochemical and geochemical reliability has been estimated. Almost 500 animal and human specimens from southwestern France upper Palaeolithic sites ranging in age from 36,000 to 9,000 years BP have been treated. It has been demonstrated that different dietary resources were isotopically distinct, with a resolution better than the expectations. Small mammals have been distinguished from ungulates, and Reindeer, Horse and Bovines presented specific isotopic signatures. Moreover, isotopic differences have been evidenced between gregarious and solitary species. Time changes of ecological patterns have been described using the isotopic signatures of some mammal species. Biomass fluctuation and exploitation have been demonstrated during upper Palaeolithic. The methodology allowed to use the isotopic signatures of animal predators as a proxy for meat resources availability in the environment. This approach allows to investigate environmental global factors as well as human behaviour with a common tool. (author)

  9. A contribution to improved flood magnitude estimation in base of palaeoflood record and climatic implications – Guadiana River (Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    J. A. Ortega

    2009-02-01

    Full Text Available The Guadiana River has a significant record of historical floods, but the systematic data record is only 59 years. From layers left by ancient floods we know about we can add new data to the record, and we can estimate maximum discharges of other floods only known by the moment of occurrence and by the damages caused. A hydraulic model has been performed in the area of Pulo de Lobo and calibrated by means of the rating curve of Pulo do Lobo Station. The palaeofloods have been dated by means of 14C y 137Cs. As non-systematic information has been used in order to calculate distribution functions, the quantiles have changed with respect to the same function when using systematic information. The results show a variation in the curves that can be blamed on the human transformations responsible for changing the hydrologic conditions as well as on the latest climate changes. High magnitude floods are related to cold periods, especially at transitional moments of change from cold to warm periods. This tendency has changed from the last medium-high magnitude flood, which took place in a systematic period. Both reasons seem to justify a change in the frequency curves indicating a recent decrease in the return period of big floods over 8000 m3 s−1. The palaeofloods indicate a bigger return period for the same water level discharge thus showing the river basin reference values in its natural condition previous to the transformation of the basin caused by anthropic action.

  10. Factors contributing to record-breaking heat waves over the Great Plains during the 1930s Dust Bowl

    Science.gov (United States)

    Cowan, T.; Hegerl, G. C.

    2016-12-01

    Record-breaking summer heat waves that plagued contiguous United States in the 1930s emerged during the decade-long "Dust Bowl" drought. Using high-quality daily temperature observations, the Dust Bowl heat wave characteristics for the Great Plains are assessed using metrics that describe variations in heat wave activity and intensity. We also quantify record-breaking heat waves over the pre-industrial period for 22 CMIP5 model multi-century realisations. The most extreme Great Plains heat wave summers in the Dust Bowl decade (e.g. 1931, 1934, 1936) were pre-conditioned by anomalously dry springs, as measured by proxy drought indices. In general, summer heat waves over the Great Plains develop 15-20 days earlier after anomalously dry springs, and are also significantly longer and hotter, indicative of the importance of land surface feedbacks in heat wave intensification. The majority of pre-industrial climate model experiments capture regionally clustered summer heat waves across North America, although the North Pacific and Atlantic sea surface temperature patterns associated with the heat waves vary considerably between models. Sea surface temperature patterns may be more important for influencing winter and spring precipitation, thus amplifying summer heat waves during drought periods. The synoptic pattern that commonly appeared during the exceptional Dust Bowl heat waves featured an anomalous broad surface pressure ridge straddling an upper level blocking anticyclone over the western United States. This forced significant subsidence and adiabatic warming over the Great Plains, and triggered anomalous southward warm advection over southern regions, prolonging and amplifying the heat waves over central United States. Importantly, the results show that despite the sparsity of stations in the 1930s, homogeneous observations are crucial in accurately quantifying the Dust Bowl decade heat waves, as opposed to solely relying on atmospheric reanalysis.

  11. Increased planned delivery contributes to declining rates of pregnancy hypertension in Australia: a population-based record linkage study.

    Science.gov (United States)

    Roberts, Christine L; Algert, Charles S; Morris, Jonathan M; Ford, Jane B

    2015-10-05

    Since the 1990s, pregnancy hypertension rates have declined in some countries, but not all. Increasing rates of early planned delivery (before the due date) have been hypothesised as the reason for the decline. The aim of this study was to explore whether early planned delivery can partly explain the declining pregnancy hypertension rates in Australia. Population-based record linkage study utilising linked birth and hospital records. A cohort of 1,076,122 deliveries in New South Wales, Australia, 2001-2012. Pregnancy hypertension (including gestational hypertension, pre-eclampsia and eclampsia) was the main outcome; pre-eclampsia was a secondary outcome. From 2001 to 2012, pregnancy hypertension rates declined by 22%, from 9.9% to 7.7%, and pre-eclampsia by 27%, from 3.3% to 2.4% (trend prate was predicted to increase to 10.5%. Examination of annual gestational age distributions showed that pregnancy hypertension rates actually declined from 38 weeks gestation and were steepest from 41 weeks; at least 36% of the decrease could be attributed to planned deliveries. The risk factors for pregnancy hypertension were also risk factors for planned delivery. It appears that an unanticipated consequence of increasing early planned deliveries is a decline in the incidence of pregnancy hypertension. Women with risk factors for hypertension were relatively more likely to be selected for early delivery. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  12. Spanish Network for Isotopes in Precipitation: Isotope Spatial distribution and contribution to the knowledge of the hydrological cycle; La Red Espanola de Vigilancia de Isotopos en la Precipitacion (REVIP): distribucion isotopica espacial y aportacion al conocimiento del ciclo hidrologico

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Teijeiro, M. F.; Rodriguez-Arevalo, J.; Castano, S.

    2009-07-01

    The results of seven years of operation of the Spanish Network for Isotopes ({sup 2}H, {sup 1}8O y {sup 3}H) in Precipitation (REVIP) are shown. this Network is managed since 2000 by the Centro de Estudios de Tecnicas Aplicadas of the Centro de Estudios y Experimentacion de Obras Publicas (CEDEX) in collaboration with the Agencia Estatal de Meteorologia (AEMET). The results of REVIP are sent to the International Atomic Energy Agency (IAEA) in order to be integrated in the Global Network for Isotopes in Precipitation (GNIP). The spatial distribution of stable isotopes ({sup 1}8O h {sup 2}H) in precipitation in Spain follows a multiple regression model, based on two geographic factors: latitude and elevation, which is strongly correlated with temperature, an important factor controlling isotope fractionation. This information on {sup 1}8O and {sup 2}H is useful to trace surface and ground waters and, combined with the information, about the spatial and temporal distribution of the Tritium ({sup 3}H) concentration in precipitation, allows to date these waters in order to estimate flow directions and velocities, and to evaluate the residence time of water resources and aquifer vulnerability. (Author)

  13. What are the factors that contribute to road accidents? An assessment of law enforcement views, ordinary drivers' opinions, and road accident records.

    Science.gov (United States)

    Rolison, Jonathan J; Regev, Shirley; Moutari, Salissou; Feeney, Aidan

    2018-06-01

    What are the main contributing factors to road accidents? Factors such as inexperience, lack of skill, and risk-taking behaviors have been associated with the collisions of young drivers. In contrast, visual, cognitive, and mobility impairment have been associated with the collisions of older drivers. We investigated the main causes of road accidents by drawing on multiple sources: expert views of police officers, lay views of the driving public, and official road accident records. In Studies 1 and 2, police officers and the public were asked about the typical causes of road traffic collisions using hypothetical accident scenarios. In Study 3, we investigated whether the views of police officers and the public about accident causation influence their recall accuracy for factors reported to contribute to hypothetical road accidents. The results show that both expert views of police officers and lay views of the driving public closely approximated the typical factors associated with the collisions of young and older drivers, as determined from official accident records. The results also reveal potential underreporting of factors in existing accident records, identifying possible inadequacies in law enforcement practices for investigating driver distraction, drug and alcohol impairment, and uncorrected or defective eyesight. Our investigation also highlights a need for accident report forms to be continuously reviewed and updated to ensure that contributing factor lists reflect the full range of factors that contribute to road accidents. Finally, the views held by police officers and the public on accident causation influenced their memory recall of factors involved in hypothetical scenarios. These findings indicate that delay in completing accident report forms should be minimised, possibly by use of mobile reporting devices at the accident scene. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Century-long Record of Black Carbon in an Ice Core from the Eastern Pamirs: Estimated Contributions from Biomass Burning

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mo; Xu, B.; Kaspari, Susan D.; Gleixner, Gerd; Schwab, Valerie; Zhao, Huabiao; Wang, Hailong; Yao, Ping

    2015-08-01

    We analyzed refractory black carbon (rBC) in an ice core spanning 1875-2000 AD from Mt. Muztagh Ata, the Eastern Pamirs, using a Single Particle Soot Photometer (SP2). Additionally a pre-existing levoglucosan record from the same ice core was used to differentiate rBC that originated from open fires, energy-related combustion of biomass, and fossil fuel combustion. Mean rBC concentrations increased four-fold since the mid-1970s and reached maximum values at the end of 1980s. The observed decrease of the rBC concentrations during the 1990s was likely driven by the economic recession of former USSR countries in Central Asia. Levoglucosan concentrations showed a similar temporal trend to rBC concentrations, exhibiting a large increase around 1980 AD followed by a decrease in the 1990s that was likely due to a decrease in energy-related biomass combustion. The time evolution of levoglucosan/rBC ratios indicated stronger emissions from open fires during the 1940s-1950s, while the increase in rBC during the 1980s-1990s was caused from an increase in energy-related combustion of biomass and fossil fuels.

  15. An ocean–ice coupled response during the last glacial: a view from a marine isotopic stage 3 record south of the Faeroe Shetland Gateway

    NARCIS (Netherlands)

    Zumaque, J.; Eynaud, F.; Zaragosi, S.; Marret, F.; Matsuzaki, K.M.; Kissel, C.; Roche, D.M.V.A.P.; Malaizé, B.; Michel, E.; Billy, I.; Richter, T.; Palis, E.

    2012-01-01

    The rapid climatic variability characterising the Marine Isotopic Stage (MIS) 3 (~60–30 cal ka BP) provides key issues to understand the atmosphere–ocean–cryosphere dynamics. Here we investigate the response of sea-surface paleoenvironments to the MIS3 climatic variability through the study of a

  16. An ocean-ice coupled response during the last glacial: a view from a marine isotopic stage 3 record south of the Faeroe Shetland Gateway

    NARCIS (Netherlands)

    Zumaque, J.; Eynaud, F.; Zaragosi, S.; Marret, F.; Matsuzaki, K.M.; Kissel, C.; Roche, D.M.; Malaize, B.; Michel, E.; Billy, I.; Richter, T.; Palis, E.

    2012-01-01

    The rapid climatic variability characterising the Marine Isotopic Stage (MIS) 3 (similar to 60-30 cal ka BP) provides key issues to understand the atmosphere-ocean-cryosphere dynamics. Here we investigate the response of sea-surface paleoenvironments to the MIS3 climatic variability through the

  17. Tree-ring stable isotopes record the impact of a foliar fungal pathogen on CO(2) assimilation and growth in Douglas-fir.

    Science.gov (United States)

    Saffell, Brandy J; Meinzer, Frederick C; Voelker, Steven L; Shaw, David C; Brooks, J Renée; Lachenbruch, Barbara; McKay, Jennifer

    2014-07-01

    Swiss needle cast (SNC) is a fungal disease of Douglas-fir (Pseudotsuga menziesii) that has recently become prevalent in coastal areas of the Pacific Northwest. We used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible reference species (western hemlock, Tsuga heterophylla) to evaluate their use as proxies for variation in past SNC infection, particularly in relation to potential explanatory climate factors. We sampled trees from an Oregon site where a fungicide trial took place from 1996 to 2000, which enabled the comparison of stable isotope values between trees with and without disease. Carbon stable isotope discrimination (Δ(13)C) of treated Douglas-fir tree-rings was greater than that of untreated Douglas-fir tree-rings during the fungicide treatment period. Both annual growth and tree-ring Δ(13)C increased with treatment such that treated Douglas-fir had values similar to co-occurring western hemlock during the treatment period. There was no difference in the tree-ring oxygen stable isotope ratio between treated and untreated Douglas-fir. Tree-ring Δ(13)C of diseased Douglas-fir was negatively correlated with relative humidity during the two previous summers, consistent with increased leaf colonization by SNC under high humidity conditions that leads to greater disease severity in following years. © 2013 John Wiley & Sons Ltd.

  18. Tree-ring stable isotopes record the impact of a foliar fungal pathogen on CO2 assimilation and growth in Douglas-fir

    Science.gov (United States)

    Swiss needle cast (SNC) is a fungal disease of Douglas-fir (Pseudotsuga menziesii) that has recently become prevalent in coastal areas of the Pacific Northwest. We used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible...

  19. Correlation of Greenland ice-core isotope profiles and the terrestrial record of the Alpine Rhine glacier for the period 32-15 ka

    NARCIS (Netherlands)

    de Jong, M.G.G.; de Graaff, L.W.S.; Seijmonsbergen, A.C.; Böhm, A.R.

    2011-01-01

    We present a newly extended stratigraphic subdivision of the Greenland NGRIP, GRIP and GISP2 ice cores for the period 32-15 ka. Our classification emphasizes the multiscale nature of the climatic oscillations. Spectral trend analysis of isotopic data supports this interpretation. We compare this

  20. A high-resolution carbon-isotope record of the Turonian stage correlated to a siliciclastic basin fill: Implications for mid-Cretaceous sea-level change

    Czech Academy of Sciences Publication Activity Database

    Uličný, David; Jarvis, I.; Gröcke, D. R.; Čech, S.; Laurin, Jiří; Olde, K.; Trabucho-Alexandre, J.; Švábenická, L.; Pedentchouk, N.

    2014-01-01

    Roč. 405, July (2014), s. 42-58 ISSN 0031-0182 R&D Projects: GA ČR GAP210/10/1991; GA MŠk LA08036 Institutional support: RVO:67985530 Keywords : eustasy * carbon isotopes * Bohemian Cretaceous Basin * Turonian * greenhouse climate * sequence stratigraphy Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.339, year: 2014

  1. Pliocene Paleoenvironments of the Awash Valley, Ethiopia: The Isotope Record of Tooth Enamel and its Relevance to the Pliocene Paleoclimate of Northeastern Africa

    Science.gov (United States)

    Bedaso, Z. K.; Wynn, J. G.; Alemseged, Z.

    2010-12-01

    Understanding patterns of Pliocene environmental and climate change using data from terrestrial deposits helps to identify factors which govern the climate, and to unravel potential links between regional and global climate conditions. We use the stable carbon (C) and oxygen (O) isotopic composition of bioapatite from fossil tooth enamel to reconstruct Pliocene environmental and climatic changes at Dikika and Galili, in the Awash valley of Ethiopia. Our application of C and O isotopes aims principally at reconstructing shifts in floral composition, such as the relative abundance of C4 grasses, and its implications for climate indicators including temperature, aridity, and seasonality, and the role of climate in early hominin evolution. C isotopic composition of tooth enamel is based on differences in C isotope discrimination between plants that use the two major photosynthetic pathways (C3 and C4), the abundance of which are driven by climate variables, and the transfer of this “signature” between plant foods in the diet of mammals and mammalian tooth enamel δ13C values (ɛdiet-enamel). A change in δ13Cenamel values between 5.26 and 3.24 Ma provides insight to early hominin environments, which varied from open woodland and grassland to closed woodland in the early to mid Pliocene at Galili and wooded grassland both in Galili and Dikika in the late Pliocene. Similarly, the O isotopic composition of tooth enamel is a function of the isotopic composition of body water, which in turn is a function of meteoric and physiological processes, and therefore may also reflect local climatic conditions if the physiological factors can be constrained. Using an O isotope enrichment factor between δ18Oenamel carbonate and δ18Obody water (ɛEC-BW =26.3) and between evaporation sensitive and insensitive taxa (ɛES-EI = 2.1-4.2), we estimate the Pliocene δ18O value of meteoric water, which ranges from -2.4 to -5.2 ‰ in early and mid Pliocene respectively. An observed

  2. A continuous high-resolution record of western South Island environmental change over the last 31,000 years from stable isotope analyses of two north-west Nelson speleothems

    International Nuclear Information System (INIS)

    Hellstrom, J.; McCulloch, M.; Stone, J.

    1997-01-01

    Core samples were taken through large sheets of calcite flowstone growing in two cave systems, Nettlebed, and Exhaleair, in north-west Nelson, New Zealand. The sampled flowstones are at elevations of 400 m asl and 600 m asl, and are both located 200m below the surface. Ten high-precision U-series dates, measured by thermal ionisation mass spectroemtry, indicate the Nettlebed flowstone grew continuously over the last 31 ka. The Exhaleair flowstone grew continuously over the last 16 ka, following a 50 ka hiatus in deposition. The speleothems from both caves show similar records of oxygen isotope variation over the last 16 ka. The carbon isotope record from Nettlebed shows considerable variation, of almost 10 per thousand from the last glacial maximum to the early Holocene. It is anticipated that these well-dated speleothem records will enable more accurate constraints to be placed on the timing of glacial advances and vegetation changes in the western South Island than are possible using the available radiocarbon ages alone. (author)

  3. Stable lead isotopic characterisation of the historical record of environmental lead contamination in dated freshwater lake sediment cores from northern and central Scotland

    Energy Technology Data Exchange (ETDEWEB)

    Eades, L.J.; Farmer, J.G. [Environmental Chemistry Unit, Department of Chemistry, University of Edinburgh, West Mains Road, EH9 3JJ, Scotland Edinburgh (United Kingdom); MacKenzie, A.B. [Scottish Universities Research and Reactor Centre, East Kilbride, G75 0QF, Scotland Glasgow (United Kingdom); Kirika, A.; Bailey-Watts, A.E. [NERC Centre for Ecology and Hydrology, EH26 0QB, Scotland Penicuik (United Kingdom)

    2002-06-20

    Sediment cores from three Scottish freshwater lakes, Loch Ness in the remote north and Loch Lomond and the Lake of Menteith, much closer to the heavily populated and industrialised central belt, were analysed for 210Pb, 137Cs, Pb and stable Pb isotopic composition (206Pb/207Pb). The radionuclide data were used to establish chronologies for the Loch Ness and Loch Lomond cores, but a chronology could not be developed for the Lake of Menteith core, in which the surface sediment had been subject to intense mixing. Although Pb concentrations generally started increasing during the mid-17th Century, a small peak occurred for Loch Ness in the early 16th Century, perhaps attributable to the influence of medieval mining and smelting in mainland Europe. Temporal trends in the pattern of Pb accumulation were similar for Loch Ness and both sites in Loch Lomond, with 40-50% of the anthropogenic Pb deposited prior to the 20th Century. Fluxes of anthropogenic Pb to the lake sediments peaked during the 1950s at all locations where chronologies could be established. The 5-fold increase in anthropogenic Pb inventory for the southern basin of Loch Lomond relative to Loch Ness reflected geographical proximity to the main polluting sources. The 206Pb/207Pb data for anthropogenic Pb in the sediments from Loch Ness and Loch Lomond exhibited largely similar trends related to five different time periods. Pre-1820, the 206Pb/207Pb ratio was close to that for coal (1.181). From 1820 to 1900, a fairly constant 206Pb/207Pb ratio of 1.17 probably resulted from a combination of emissions from the smelting of indigenous Pb ore (1.170) and coal burning (1.181) in Scotland, and industrial activity to the south in England, where Australian Pb of characteristically low 206Pb/207Pb ratio (1.04) was already in use. From 1901 to 1930, the 206Pb/207Pb ratio declined by <0.01, due to the increasing influence of Australian Pb. From 1931 to 1975/1985, the 206Pb/207Pb ratio of anthropogenic Pb declined by a

  4. Stable lead isotopic characterisation of the historical record of environmental lead contamination in dated freshwater lake sediment cores from northern and central Scotland.

    Science.gov (United States)

    Eades, L J; Farmer, J G; MacKenzie, A B; Kirika, A; Bailey-Watts, A E

    2002-06-20

    Sediment cores from three Scottish freshwater lakes, Loch Ness in the remote north and Loch Lomond and the Lake of Menteith, much closer to the heavily populated and industrialised central belt were analysed for 210Pb, 137Cs, Pb and stable Pb isotopic composition (206Pb/207Pb). The radionuclide data were used to establish chronologies for the Loch Ness and Loch Lomond cores, but a chronology could not be developed for the Lake of Menteith core, in which the surface sediment had been subject to intense mixing. Although Pb concentrations generally started increasing during the mid-17th Century, a small peak occurred for Loch Ness in the early 16th Century, perhaps attributable to the influence of medieval mining and smelting in mainland Europe. Temporal trends in the pattern of Pb accumulation were similar for Loch Ness and both sites in Loch Lomond, with 40-50% of the anthropogenic Pb deposited prior to the 20th Century. Fluxes of anthropogenic Pb to the lake sediments peaked during the 1950s at all locations where chronologies could be established. The 5-fold increase in anthropogenic Pb inventory for the southern basin of Loch Lomond relative to Loch Ness reflected geographical proximity to the main polluting sources. The 206Pb/207Pb data for anthropogenic Pb in the sediments from Loch Ness and Loch Lomond exhibited largely similar trends related to five different time periods. Pre-1820, the 206Pb/207Pb ratio was close to that for coal (1.181). From 1820 to 1900, a fairly constant 206Pb/207Pb ratio of approximately 1.17 probably resulted from a combination of emissions from the smelting of indigenous Pb ore (1.170) and coal burning (1.181) in Scotland, and industrial activity to the south in England, where Australian Pb of characteristically low 206Pb/207Pb ratio (1.04) was already in use. From 1901 to 1930, the 206Pb/207Pb ratio declined by <0.01, due to the increasing influence of Australian Pb. From 1931 to 1975/1985, the 206Pb/207Pb ratio of anthropogenic Pb

  5. Isotopic studies of Yucca Mountain soil fluids and carbonate pedogenesis

    International Nuclear Information System (INIS)

    McConnaughey, T.A.; Whelan, J.F.; Wickland, K.P.; Moscati, R.J.

    1994-01-01

    Secondary carbonates occurring within the soils, faults, and subsurface fractures of Yucca Mountain contain some of the best available records of paleoclimate and palehydrology for the potential radioactive waste repository site. This article discusses conceptual and analytical advances being made with regard to the interpretation of stable isotope data from pedogenic carbonates, specifically related to the 13 C content of soil CO 2 , CaCO 3 , precipitation mechanisms, and isotopic fractionations between parent fluids and precipitating carbonates. The 13 C content of soil carbon dioxide from Yucca Mountain and vicinity shows most of the usual patterns expected in such contexts: Decreasing 13 C content with depth decreasing 13 C with altitude and reduced 13 C during spring. These patterns exist within the domain of a noisy data set; soil and vegetational heterogeneities, weather, and other factors apparently contribute to isotopic variability in the system. Several soil calcification mechanisms appear to be important, involving characteristic physical and chemical environments and isotopic fractionations. When CO 2 loss from thin soil solutions is an important driving factor, carbonates may contain excess heavy isotopes, compared to equilibrium precipitation with soil fluids. When root calcification serves as a proton generator for plant absorption of soil nutrients, heavy isotope deficiencies are likely. Successive cycles of dissolution and reprecipitation mix and redistribute pedogenic carbonates, and tend to isotopically homogenize and equilibrate pedogenic carbonates with soil fluids

  6. Using nitrogen concentration and isotopic composition in lichens to spatially assess the relative contribution of atmospheric nitrogen sources in complex landscapes

    International Nuclear Information System (INIS)

    Pinho, P.; Barros, C.; Augusto, S.; Pereira, M.J.

    2017-01-01

    Reactive nitrogen (Nr) is an important driver of global change, causing alterations in ecosystem biodiversity and functionality. Environmental assessments require monitoring the emission and deposition of both the amount and types of Nr. This is especially important in heterogeneous landscapes, as different land-cover types emit particular forms of Nr to the atmosphere, which can impact ecosystems distinctively. Such assessments require high spatial resolution maps that also integrate temporal variations, and can only be feasibly achieved by using ecological indicators. Our aim was to rank land-cover types according to the amount and form of emitted atmospheric Nr in a complex landscape with multiple sources of N. To do so, we measured and mapped nitrogen concentration and isotopic composition in lichen thalli, which we then related to land-cover data. Results suggested that, at the landscape scale, intensive agriculture and urban areas were the most important sources of Nr to the atmosphere. Additionally, the ocean greatly influences Nr in land, by providing air with low Nr concentration and a unique isotopic composition. These results have important consequences for managing air pollution at the regional level, as they provide critical information for modeling Nr emission and deposition across regional as well as continental scales. - Highlights: • Which land-cover types are reactive nitrogen sources or sinks at a landscape level? • Nitrogen concentration and isotopic composition were analyzed in lichens. • This allowed determination of the main nitrogen sources: agricultural and urban areas. • Marine sources provided persistent low concentrations of reactive nitrogen. • The typical signature of each source was also determined. - Reactive-nitrogen concentration and isotopic composition in lichens were used to rank Nr sources at a landscape level.

  7. Proxy Records of the Indonesian Low and the El Ni{tilde n}o-Southern Oscillation (ENSO) from Stable Isotope Measurements of Indonesian Reef Corals

    Energy Technology Data Exchange (ETDEWEB)

    Moore, M.D.

    1995-12-31

    The Earth`s largest atmospheric convective center is the Indonesian Low. It generates the Australasian monsoon, drives the zonal tropospheric Walker Circulation, and is implicated in the genesis of the El Nino-Southern Oscillation (ENSO). The long-term variability of the Indonesian Low is poorly characterized, yet such information is crucial for evaluating whether changes in the strength and frequency of ENSO events are a possible manifestation of global warming. Stable oxygen isotope ratios ({delta}{sup 18}O) in shallow-water reef coral skeletons track topical convective activity over hundreds of years because the input of isotopically-depleted rainwater dilutes seawater {delta}{sup 18}O. Corals also impose a temperature-dependent fractionation on {delta}{sup 18}O, but where annual rainfall is high and sea surface temperature (SST) variability is low the freshwater flux effect dominates.

  8. Sulphur isotope measurements on sulphates from Antarctic atmospheric precipitations, lake waters and salt efflorescences: a contribution to the study of the natural sulphur cycle

    International Nuclear Information System (INIS)

    Wand, U.; Maass, I.; Haendel, D.

    1987-01-01

    Sulphur isotope analyses are an important tool for the study of the natural sulphur cycle. However, on the northern hemisphere such studies particularly of the atmospheric component of the cycle are seriously hampered and in many regions practically impossible because of the high emission rate of anthropogenic sulphur. Only in remote areas of the world such as the Antarctic 34 S analyses can be used with success to identify the various natural sulphur sources (marine, biogenic and volcanic sources). We report here preliminary results of 34 S isotope measurements on sulphates from recent atmospheric precipitations (snow), lake waters and salt efflorescences sampled in the Schirmacher Oasis and the Wohlthat Massif, central Queen Maud Land, East Antarctica. Except for 4 efflorescence samples the sulphates investigated in this work are enriched in 34 S relative to the meteoritic sulphur standard (CDT). On an average the sulphates of our study area are isotopically lighter than those from the McMurdo region, South Victoria land. The latter region is characterized by the predominance of salts of marine origin. (author)

  9. Isotopic clusters

    International Nuclear Information System (INIS)

    Geraedts, J.M.P.

    1983-01-01

    Spectra of isotopically mixed clusters (dimers of SF 6 ) are calculated as well as transition frequencies. The result leads to speculations about the suitability of the laser-cluster fragmentation process for isotope separation. (Auth.)

  10. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, Eugene E.

    2006-06-19

    The following article is an edited transcript based on the Turnbull Lecture given by Eugene E. Haller at the 2005 Materials Research Society Fall Meeting in Boston on November 29, 2005. The David Turnbull Lectureship is awarded to recognize the career of a scientist who has made outstanding contributions to understanding materials phenomena and properties through research, writing, and lecturing, as exemplified by the life work of David Turnbull. Haller was named the 2005 David Turnbull Lecturer for his 'pioneering achievements and leadership in establishing the field of isotopically engineered semiconductors; for outstanding contributions to materials growth, doping and diffusion; and for excellence in lecturing, writing, and fostering international collaborations'. The scientific interest, increased availability, and technological promise of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled semiconductor crystals. This article reviews results obtained with isotopically controlled semiconductor bulk and thin-film heterostructures. Isotopic composition affects several properties such as phonon energies, band structure, and lattice constant in subtle, but, for their physical understanding, significant ways. Large isotope-related effects are observed for thermal conductivity in local vibrational modes of impurities and after neutron transmutation doping. Spectacularly sharp photoluminescence lines have been observed in ultrapure, isotopically enriched silicon crystals. Isotope multilayer structures are especially well suited for simultaneous self- and dopant-diffusion studies. The absence of any chemical, mechanical, or electrical driving forces makes possible the study of an ideal random-walk problem. Isotopically controlled semiconductors may find applications in quantum computing, nanoscience, and spintronics.

  11. Stable isotopes

    International Nuclear Information System (INIS)

    Evans, D.K.

    1986-01-01

    Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

  12. Isotope separation

    International Nuclear Information System (INIS)

    Eerkens, J.W.

    1979-01-01

    A method of isotope separation is described which involves the use of a laser photon beam to selectively induce energy level transitions of an isotope molecule containing the isotope to be separated. The use of the technique for 235 U enrichment is demonstrated. (UK)

  13. Thermal and chemical evolution in the early solar system as recorded by FUN CAIs: Part I - Petrology, mineral chemistry, and isotopic composition of Allende FUN CAI CMS-1

    Science.gov (United States)

    Williams, C. D.; Ushikubo, T.; Bullock, E. S.; Janney, P. E.; Hines, R. R.; Kita, N. T.; Hervig, R. L.; MacPherson, G. J.; Mendybaev, R. A.; Richter, F. M.; Wadhwa, M.

    2017-03-01

    Detailed petrologic, geochemical and isotopic analyses of a new FUN CAI from the Allende CV3 meteorite (designated CMS-1) indicate that it formed by extensive melting and evaporation of primitive precursor material(s). The precursor material(s) condensed in a 16O-rich region (δ17O and δ18O ∼ -49‰) of the inner solar nebula dominated by gas of solar composition at total pressures of ∼10-3-10-6 bar. Subsequent melting of the precursor material(s) was accompanied by evaporative loss of magnesium, silicon and oxygen resulting in large mass-dependent isotope fractionations in these elements (δ25Mg = 30.71-39.26‰, δ29Si = 14.98-16.65‰, and δ18O = -41.57 to -15.50‰). This evaporative loss resulted in a bulk composition similar to that of compact Type A and Type B CAIs, but very distinct from the composition of the original precursor condensate(s). Kinetic fractionation factors and the measured mass-dependent fractionation of silicon and magnesium in CMS-1 suggest that ∼80% of the silicon and ∼85% of the magnesium were lost from its precursor material(s) through evaporative processes. These results suggest that the precursor material(s) of normal and FUN CAIs condensed in similar environments, but subsequently evolved under vastly different conditions such as total gas pressure. The chemical and isotopic differences between normal and FUN CAIs could be explained by sorting of early solar system materials into distinct physical and chemical regimes, in conjunction with discrete heating events, within the protoplanetary disk.

  14. New stable isotope records of sediment cores from the SE Arabian Sea - Inferences on the variations in monsoon regime during the late Quaternery

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.

    , Vidyanagar 671 123, India We reconstruct here the changes in regional hydr o- graphy related to the fluctuations in Indian mo n soons du r ing the late Quaternary based on the stable isotope composition of the foraminifers and organic matter in three... value du r ing the early Holocene for the eastern Arabian Sea 21 . The SW monsoon intensity was very weak and the dry NE mo n soon was the dominant feature during the LGM in the Ar a bian Sea 3 . The cool winds of the north - easterly winter...

  15. A 1000-year record of dry conditions in the eastern Canadian prairies reconstructed from oxygen and carbon isotope measurements on Lake Winnipeg sediment organics

    Science.gov (United States)

    Buhay, W.M.; Simpson, S.; Thorleifson, H.; Lewis, M.; King, J.; Telka, A.; Wilkinson, Philip M.; Babb, J.; Timsic, S.; Bailey, D.

    2009-01-01

    A short sediment core (162 cm), covering the period AD 920-1999, was sampled from the south basin of Lake Winnipeg for a suite of multi-proxy analyses leading towards a detailed characterisation of the recent millennial lake environment and hydroclimate of southern Manitoba, Canada. Information on the frequency and duration of major dry periods in southern Manitoba, in light of the changes that are likely to occur as a result of an increasingly warming atmosphere, is of specific interest in this study. Intervals of relatively enriched lake sediment cellulose oxygen isotope values (??18Ocellulose) were found to occur from AD 1180 to 1230 (error range: AD 1104-1231 to 1160-1280), 1610-1640 (error range: AD 1571-1634 to 1603-1662), 1670-1720 (error range: AD 1643-1697 to 1692-1738) and 1750-1780 (error range: AD 1724-1766 to 1756-1794). Regional water balance, inferred from calculated Lake Winnipeg water oxygen isotope values (??18Oinf-lw), suggest that the ratio of lake evaporation to catchment input may have been 25-40% higher during these isotopically distinct periods. Associated with the enriched d??18Ocellulose intervals are some depleted carbon isotope values associated with more abundantly preserved sediment organic matter (d??13COM). These suggest reduced microbial oxidation of terrestrially derived organic matter and/or subdued lake productivity during periods of minimised input of nutrients from the catchment area. With reference to other corroborating evidence, it is suggested that the AD 1180-1230, 1610-1640, 1670-1720 and 1750-1780 intervals represent four distinctly drier periods (droughts) in southern Manitoba, Canada. Additionally, lower-magnitude and duration dry periods may have also occurred from 1320 to 1340 (error range: AD 1257-1363), 1530-1540 (error range: AD 1490-1565 to 1498-1572) and 1570-1580 (error range: AD 1531-1599 to 1539-1606). ?? 2009 John Wiley & Sons, Ltd.

  16. The lacustrine sediment record of Oberwinkler Maar (Eifel, Germany): Chironomid and macro-remain-based inferences of environmental changes during Oxygen Isotope Stage 3

    NARCIS (Netherlands)

    Engels, S.; Bohncke, S.J.P.; Heiri, O.; Schaber, K.; Sirocko, F.

    2008-01-01

    The lacustrine record of Oberwinkler Maar (Eifel, Germany) is the northernmost continuous record documenting the Weichselian Pleniglacial in central Europe - a period characterized by multiple abrupt climate oscillations known as the Dansgaard/Oeschger cycles. Here, the results of a high-resolution

  17. From patient care to research: a validation study examining the factors contributing to data quality in a primary care electronic medical record database.

    Science.gov (United States)

    Coleman, Nathan; Halas, Gayle; Peeler, William; Casaclang, Natalie; Williamson, Tyler; Katz, Alan

    2015-02-05

    Electronic Medical Records (EMRs) are increasingly used in the provision of primary care and have been compiled into databases which can be utilized for surveillance, research and informing practice. The primary purpose of these records is for the provision of individual patient care; validation and examination of underlying limitations is crucial for use for research and data quality improvement. This study examines and describes the validity of chronic disease case definition algorithms and factors affecting data quality in a primary care EMR database. A retrospective chart audit of an age stratified random sample was used to validate and examine diagnostic algorithms applied to EMR data from the Manitoba Primary Care Research Network (MaPCReN), part of the Canadian Primary Care Sentinel Surveillance Network (CPCSSN). The presence of diabetes, hypertension, depression, osteoarthritis and chronic obstructive pulmonary disease (COPD) was determined by review of the medical record and compared to algorithm identified cases to identify discrepancies and describe the underlying contributing factors. The algorithm for diabetes had high sensitivity, specificity and positive predictive value (PPV) with all scores being over 90%. Specificities of the algorithms were greater than 90% for all conditions except for hypertension at 79.2%. The largest deficits in algorithm performance included poor PPV for COPD at 36.7% and limited sensitivity for COPD, depression and osteoarthritis at 72.0%, 73.3% and 63.2% respectively. Main sources of discrepancy included missing coding, alternative coding, inappropriate diagnosis detection based on medications used for alternate indications, inappropriate exclusion due to comorbidity and loss of data. Comparison to medical chart review shows that at MaPCReN the CPCSSN case finding algorithms are valid with a few limitations. This study provides the basis for the validated data to be utilized for research and informs users of its

  18. Isotopes of carbon, nitrogen and oxygen reveal contributions of submarine groundwater and septic systems discharges to algal bloom in Boracay Island

    International Nuclear Information System (INIS)

    Sucgang, Raymond; Pabroa, Preciosa Corazon; Mendoza, Norman; Racho, Joseph Michael; Bautista, Angel; Morco, Ryan; Petrache, Christina; Castaneda, Soledad; Dela Rosa, Alumanda

    2014-01-01

    The study showed that critical areas in Boracay island were contaminated by coliform bacteria and blue green algae (cyanobacteria). The distribution of tritium, 18 O, 15 N and 13 C in seawater, biota and sediments in the inter tidal zone, helped to identify sites with septic sewage outflows and submarine groundwater discharge, SGD. Nitrates (from 0.0 to 2.3 parts per million, ppm) and nutrients were discovered in seawater, particularly in four identified sites in the bathing zone. Point sources of infiltrating plumes were exposed by anomalies in tritium and 18 O in sea water. Septic and canal outflows as well as land based run-offs and submarine groundwater discharge were the identified causes of nutrient enrichments in sites with eminent algal bloom. The isotope composition implied that algae acquire nutrients from septic contamination, while a number of corals assimilate inorganic fertilizer nutrients from land-based plumes and SGD. The elements identified in sediments and corals were related to the natural mineral matrix of calcareous beach zone materials, however, sporadic spikes of lead, chromium and zinc were detected in particular sites at certain depths. These element spikes proxy processes linked to anthropogenic pollution and or organic matter decomposition in the sediment-water interfaces. The practicality of applying isotope-based techniques in conjunction with other chemical methods for the tracking down of the sources of nutrient contamination in polluted systems in demonstrated by the study.(author)

  19. The application of isotope and geochemical techniques to reveal contributions of submarine groundwater and septic systems discharges to algal bloom in Boracay Island

    International Nuclear Information System (INIS)

    Sucgang, Raymond J.; Pabroa, Preciosa Corazon C.; Mendoza, Norman DS.; Racho, Joseph Michael D.; Bautista VII, Angel P.; Jimenez, Gloria R.; Cuyco, Danilo A.; Dawal, Carla S.; Petrache, Christina A.; Castaneda, Soledad S.; Dela Rosa, Alumanda M.

    2014-01-01

    The study shows that critical areas in Boracay island are contaminated by coliform bacteria and blue green algae (cyanobacteria). The distribution of tritium, 18 O, 15 N, and 13 C in seawater, biota and sediments in the intertidal zone, helped to identify sites with specific sewage outflows and submarine groundwater discharge, SGD, Nitrates (from, 0.0 to 2.3 parts per million, ppm) and nutrients were discovered in seawater, particularly in four identified sites in the bathing zone. Point sources of infiltrating plumes were exposed by anomalies in tritium and 18 O in sea water. Septic and canal outflows as well as land based run-offs and submarine groundwater discharge were the identified causes of nutrient enrichments in sites with eminent algal bloom. The isotope composition implied that algae acquire nutrients from septic contamination, while a number of corals assimilate inorganic fertilizer nutrients from land-based plumes and SGD. The elements identified in sediments and corals were related to the natural mineral matrix of calcareous beach zone materials; however, sporadic spikes of lead, chromium and zinc were detected in particular sites at certain depths. These element spikes proxy processes linked to anthropogenic pollution and or organic matter decomposition in the sediment-water interfaces. The practicality of applying isotope-based techniques in conjunction with other chemical methods for the tracking down of the sources of nutrient contamination in polluted systems is demonstrated by the study.

  20. Using nitrogen concentration and isotopic composition in lichens to spatially assess the relative contribution of atmospheric nitrogen sources in complex landscapes.

    Science.gov (United States)

    Pinho, P; Barros, C; Augusto, S; Pereira, M J; Máguas, C; Branquinho, C

    2017-11-01

    Reactive nitrogen (Nr) is an important driver of global change, causing alterations in ecosystem biodiversity and functionality. Environmental assessments require monitoring the emission and deposition of both the amount and types of Nr. This is especially important in heterogeneous landscapes, as different land-cover types emit particular forms of Nr to the atmosphere, which can impact ecosystems distinctively. Such assessments require high spatial resolution maps that also integrate temporal variations, and can only be feasibly achieved by using ecological indicators. Our aim was to rank land-cover types according to the amount and form of emitted atmospheric Nr in a complex landscape with multiple sources of N. To do so, we measured and mapped nitrogen concentration and isotopic composition in lichen thalli, which we then related to land-cover data. Results suggested that, at the landscape scale, intensive agriculture and urban areas were the most important sources of Nr to the atmosphere. Additionally, the ocean greatly influences Nr in land, by providing air with low Nr concentration and a unique isotopic composition. These results have important consequences for managing air pollution at the regional level, as they provide critical information for modeling Nr emission and deposition across regional as well as continental scales. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Contribution of NAD 2D-NMR in liquid crystals to the determination of hydrogen isotope profile of methyl groups in miliacin

    Science.gov (United States)

    Berdagué, Philippe; Lesot, Philippe; Jacob, Jérémy; Terwilliger, Valery J.; Le Milbeau, Claude

    2016-01-01

    The hydrogen isotopic composition (δD or (D/H) value) of molecular biomarkers preserved in sedimentary archives is increasingly used to provide clues about the evolution of past climatic conditions. The rationale is that intact biomarkers retain isotopic information related to the climatic conditions that prevailed at the time of their synthesis. Some of these biomarkers may be degraded during diagenesis, however. The extent to which these degradations alter the original δD value of the source biomarker is presently debated and the capacity to resolve this question by determination of compound-specific δD values alone is limited. The ;bulk; or ;global; δD value of any molecule is in fact a composite of δD values at each site within this molecule (δDi or (D/H)i with i = number of hydrogen/deuterium atoms in the considered molecule). Determination of this site-specific δDi value in biomarkers could not only yield outstanding paleoenvironmental information but also help forecast the impacts of diagenesis and define essential steps in biosynthetic pathways. This task is analytically challenging. Here, we examined the capabilities of natural abundance deuterium 2D-NMR (NAD 2D-NMR) using homopolypeptide liquid crystals as an NMR solvent to: (i) analyze the NAD spectra of biomakers; (ii) determine the site-specific distribution of hydrogen in the nine methyl groups (δDMei with i = 23-31) of miliacin, a pentacyclic triterpene of the amyrin family and key biomarker for broomcorn millet in sedimentary archives. Relative (D/H)Mei values were established by anisotropic NAD 2D-NMR. Then absolute δDMei values were obtained by determining δDMei value of the methoxy group of miliacin using two independent approaches: isotropic NAD NMR (SNIF-NMR™) and GC-irMS. The resulting isotope profile for miliacin shows, for the first time, large variations in δDMei values that can directly be explained by biosynthetic processes. This approach has also the potential to permit

  2. Equipment for isotope diagnostics

    International Nuclear Information System (INIS)

    Platz, W.

    1976-01-01

    The invention concerns an improvement of equipment for isotope diagnostics allowing to mark special intensity ranges of the recorded measurements by means of different colors. For undisturbed operation it is of advantage to avoid electric circuits between movable and unmovable parts of the color recorder. According to the invention, long gear wheels of glass fiber-reinforced polyamide are used for these connections. (ORU) [de

  3. The 129iodine bomb pulse recorded in Mississippi River Delta sediments: results from isotopes of I, Pu, Cs, Pb, and C

    Science.gov (United States)

    Oktay, S. D.; Santschi, P. H.; Moran, J. E.; Sharma, P.

    2000-03-01

    129I ( t1/2 = 1.56 × 10 7 yr) has both natural as well as anthropogenic sources. Anthropogenic sources from nuclear reprocessing discharges and bomb test fallout have completely overwhelmed the natural signal on the surface of the earth in the last 50 years. However, the transfer functions in and out of environmental compartments are not well known due to temporal variations in the sources of 129I and to a lack of knowledge regarding the forms of iodine. From a vertical profile of 129I/ 127I ratios in sediments located in the Mississippi Delta region in approximately 60 meters water depth, the 129I input function to this region was reconstructed. Dates in the core were assigned based on the plutonium peak at 20 cm depth (assumed to have been deposited in 1963) and the excess 210Pb profile in the same depth interval, and below that, based on the steadily decreasing 240Pu/ 239Pu ratios from a ratio of 0.18 at 22 cm to 0.05 at 57 cm depth, the 1953 horizon. These low 240Pu/ 239Pu values are attributed to low yield, close-in, tropospherically transported bomb fallout produced from the Nevada test site in the early 1950s, which had a value of about 0.035, and strongly suggest a terrestrial source for Pu isotopes. 129I/ 127I ratios increased from 2 × 10 -10 at 3 cm to 4 × 10 -10 at 20 cm, and from there decreased monotonously to pre-anthropogenic values at 53 cm and below. 129I concentrations ranged from 8-13 × 10 6 atoms/g in the top 20 cm, and decreased to values of less than 1 × 10 6 atoms/g below 50 cm. Atom ratios of 129I/ 137Cs, decay corrected to 1962, the year of maximum radionuclide production, are about 0.3, very close to the production ratios of about 0.2 during atomic bomb tests. This evidence, combined with other observations, strongly suggests that 129I in Mississippi River Delta sediments originates from atomic bomb fallout eroded from soils of the Mississippi River drainage basin, with little alteration of the isotopic ratios during transport from

  4. Health of the coral reefs at the US Navy Base, Guantánamo Bay, Cuba: A preliminary report based on isotopic records from gorgonians

    International Nuclear Information System (INIS)

    Risk, Michael J.; Burchell, Meghan; Brunton, Dalston A.; McCord, Michael R.

    2014-01-01

    Specimens of the gorgonian Plexaura homomalla were sampled from several areas along the fringing reefs fronting the United States Naval Base at Guantánamo Bay, Cuba. Sample coverage extended from apparently healthy reefs in oceanic waters to declining reefs located in the plume of the drainage from upper parts of Guantánamo Bay. Tentacle tips were excised, and trunk sections were cut and polished. Stable isotope ratios of nitrogen (δ 15 N) and carbon indicate a strong correlation of reef health with proximity to the plume of the river. Of all the worldwide cases in which land-based sources of pollution have impacted reefs, this one may well be the most intractable. The US Navy has jurisdiction over the reefs, with the obligation to protect them, yet the threat comes down the river from Cuba

  5. Paleohydrogeological events recorded by stable isotopes, fluid inclusions and trace elements in fracture minerals in crystalline rock, Simpevarp area, SE Sweden

    International Nuclear Information System (INIS)

    Drake, Henrik; Tullborg, Eva-Lena

    2009-01-01

    Fracture minerals calcite, pyrite, gypsum, barite and quartz, formed during several events have been analysed for δ 13 C, δ 18 O, δ 34 S, 87 Sr/ 86 Sr, trace element chemistry and fluid inclusions in order to gain knowledge of the paleohydrogeological evolution of the Simpevarp area, south-eastern Sweden. This area is dominated by Proterozoic crystalline rocks and is currently being investigated by the Swedish Nuclear Fuel and Waste Management Co. (SKB) in order to find a suitable location for a deep-seated repository for spent nuclear fuel. Knowledge of the paleohydrogeological evolution is essential to understand the stability or evolution of the groundwater system over a time scale relevant to the performance assessment for a spent nuclear fuel repository. The ages of the minerals analysed range from the Proterozoic to possibly the Quaternary. The Proterozoic calcite and pyrite show inorganic and hydrothermal-magmatic stable isotope signatures and were probably formed during a long time period as indicated by the large span in temperatures (c. 200-360 deg. C) and salinities (0-24 wt.% eq. CaCl 2 ), obtained from fluid inclusion analyses. The Paleozoic minerals were formed from organically influenced brine-type fluids at temperatures of 80-145 deg. C. The isotopic results indicate that low temperature calcite and pyrite may have formed during different events ranging in time possibly from the end of the Paleozoic until the Quaternary. Formation conditions ranging from fresh to brackish and saline waters have been distinguished based on calcite crystal morphologies. The combination of δ 18 O and crystal morphologies show that the fresh-saline water interface has changed considerably over time, and water similar to the present meteoric water and brackish seawater at the site, have most probably earlier been residing in the bedrock. Organic influence and closed system in situ microbial activity causing disequilibrium are indicated by extremely low δ 13 C (down

  6. Health of the coral reefs at the US Navy Base, Guantánamo Bay, Cuba: a preliminary report based on isotopic records from gorgonians.

    Science.gov (United States)

    Risk, Michael J; Burchell, Meghan; Brunton, Dalston A; McCord, Michael R

    2014-06-15

    Specimens of the gorgonian Plexaura homomalla were sampled from several areas along the fringing reefs fronting the United States Naval Base at Guantánamo Bay, Cuba. Sample coverage extended from apparently healthy reefs in oceanic waters to declining reefs located in the plume of the drainage from upper parts of Guantánamo Bay. Tentacle tips were excised, and trunk sections were cut and polished. Stable isotope ratios of nitrogen (δ(15)N) and carbon indicate a strong correlation of reef health with proximity to the plume of the river. Of all the worldwide cases in which land-based sources of pollution have impacted reefs, this one may well be the most intractable. The US Navy has jurisdiction over the reefs, with the obligation to protect them, yet the threat comes down the river from Cuba. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Equatorial seawater temperatures and latitudinal temperature gradients during the Middle to Late Jurassic: the stable isotope record of brachiopods and oysters from Gebel Maghara, Egypt

    Science.gov (United States)

    Alberti, Matthias; Fürsich, Franz T.; Abdelhady, Ahmed A.; Andersen, Nils

    2017-04-01

    The Jurassic climate has traditionally been described as equable, warmer than today, with weak latitudinal temperature gradients, and no polar glaciations. This view changed over the last decades with studies pointing to distinct climate fluctuations and the occasional presence of polar ice caps. Most of these temperature reconstructions are based on stable isotope analyses of fossil shells from Europe. Additional data from other parts of the world is slowly completing the picture. Gebel Maghara in the northern Sinai Peninsula of Egypt exposes a thick Jurassic succession. After a phase of terrestrial sedimentation in the Early Jurassic, marine conditions dominated since the end of the Aalenian. The stable isotope (δ18O, δ13C) composition of brachiopod and oyster shells was used to reconstruct seawater temperatures from the Bajocian to the Kimmeridgian at a palaeolatitude of ca. 3°N. Throughout this time interval, temperatures were comparatively constant aorund an average of 25.7°C. Slightly warmer conditions existed in the Early Bathonian ( 27.0°C), while the Kimmeridgian shows the lowest temperatures ( 24.3°C). The seasonality has been reconstructed with the help of high-resolution sampling of two oyster shells and was found to be very low (temperature gradients. During the Middle Jurassic, this gradient was much steeper than previously expected and comparable to today. During the Kimmeridgian, temperatures in Europe were generally warmer leading to weaker latitudinal gradients. Based on currently used estimates for the δ18O value of seawater during the Jurassic, reconstructed water temperatures for localities above the thermocline in Egypt and Europe were mostly lower than Recent sea-surface temperatures. These results improve our understanding of the Jurassic climate and its influence on marine faunal diversity patterns.

  8. 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.

  9. Crust-mantle contribution to Andean magmatism

    International Nuclear Information System (INIS)

    Ruiz, J; Hildreth, W; Chesley, J

    2001-01-01

    represent purely mantle-derived melts (nominally ca. 0.13). The Os-isotopic system mimics the variations recorded by the other isotopic systems but is significantly magnified, demonstrating its power for evaluating crustal contributions to arc-magma genesis. Mixing calculations suggest that the Os isotopic values of the Chilean samples represent mixing of mantle-derived magmas with 20% or more of material derived from mafic lower crust (au)

  10. 100,000-year-long terrestrial record of millennial-scale linkage between eastern North American mid-latitude paleovegetation shifts and Greenland ice-core oxygen isotope trends

    Science.gov (United States)

    Litwin, Ronald J.; Smoot, Joseph P.; Pavich, Milan J.; Markewich, Helaine Walsh; Brook, George; Durika, Nancy J.

    2013-01-01

    We document frequent, rapid, strong, millennial-scale paleovegetation shifts throughout the late Pleistocene, within a 100,000+ yr interval (~ 115–15 ka) of terrestrial sediments from the mid-Atlantic Region (MAR) of North America. High-resolution analyses of fossil pollen from one core locality revealed a continuously shifting sequence of thermally dependent forest assemblages, ranging between two endmembers: subtropical oak-tupelo-bald cypress-gum forest and high boreal spruce-pine forest. Sedimentary textural evidence indicates fluvial, paludal, and loess deposition, and paleosol formation, representing sequential freshwater to subaerial environments in which this record was deposited. Its total age"depth model, based on radiocarbon and optically stimulated luminescence ages, ranges from terrestrial oxygen isotope stages (OIS) 6 to 1. The particular core sub-interval presented here is correlative in trend and timing to that portion of the oxygen isotope sequence common among several Greenland ice cores: interstades GI2 to GI24 (≈ OIS2–5 d). This site thus provides the first evidence for an essentially complete series of "Dansgaard"Oeschger" climate events in the MAR. These data reveal that the ~ 100,000 yr preceding the Late Glacial and Holocene in the MAR of North America were characterized by frequently and dynamically changing climate states, and by vegetation shifts that closely tracked the Greenland paleoclimate sequence.

  11. Development of Stable Isotope Technology

    International Nuclear Information System (INIS)

    Jeong, Do Young; Kim, Cheol Jung; Han, Jae Min

    2009-03-01

    KAERI has obtained an advanced technology with singular originality for laser stable isotope separation. Objectives for this project are to get production technology of Tl-203 stable isotope used for medical application and are to establish the foundation of the pilot system, while we are taking aim at 'Laser Isotope Separation Technology to make resistance to the nuclear proliferation'. And we will contribute to ensuring a nuclear transparency in the world society by taking part in a practical group of NSG and being collaboration with various international groups related to stable isotope separation technology

  12. Modern Microbial Ecosystems are a Key to Understanding Our Biosphere's Early Evolution and its Contributions To The Atmosphere and Rock Record

    Science.gov (United States)

    DesMarais, David J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The survival of our early biosphere depended upon efficient coordination anion- diverse microbial populations. Microbial mats exhibit a 3.46-billion-year fossil record, thus they are the oldest known ecosystems. Photosynthetic microbial mats were key because, today, sunlight powers more than 99 percent of global primary productivity. Thus photosynthetic ecosystems have affected the atmosphere profoundly and have created the most pervasive, easily-detected fossils. Photosynthetic biospheres elsewhere will be most detectible via telescopes or spacecraft. As a part of the Astrobiology Institute, our Ames Microbial Ecosystems group examines the roles played by ecological processes in the early evolution of our biosphere, as recorded in geologic fossils and in the macromolecules of living cells: (1) We are defining the microbial mat microenvironment, which was an important milieu for early evolution. (2) We are comparing mats in contrasting environments to discern strategies of adaptation and diversification, traits that were key for long-term survival. (3) We have selected sites that mimic key environmental attributes of early Earth and thereby focus upon evolutionary adaptations to long-term changes in the global environment. (4) Our studies of gas exchange contribute to better estimates of biogenic gases in Earth's early atmosphere. This group therefore directly addresses the question: How have the Earth and its biosphere influenced each other over time Our studies strengthen the systematics for interpreting the microbial fossil record and thereby enhance astrobiological studies of martian samples. Our models of biogenic gas emissions will enhance models of atmospheres that might be detected on inhabited extrasolar planets. This work therefore also addresses the question: How can other biospheres be recogniZed" Our choice of field sites helps us explore Earth's evolving early environment. For example, modern mats that occupy thermal springs and certain freshwater

  13. Isotope enrichment

    International Nuclear Information System (INIS)

    Garbuny, M.

    1979-01-01

    The invention discloses a method for deriving, from a starting material including an element having a plurality of isotopes, derived material enriched in one isotope of the element. The starting material is deposited on a substrate at less than a critical submonatomic surface density, typically less than 10 16 atoms per square centimeter. The deposit is then selectively irradiated by a laser (maser or electronic oscillator) beam with monochromatic coherent radiation resonant with the one isotope causing the material including the one istope to escape from the substrate. The escaping enriched material is then collected. Where the element has two isotopes, one of which is to be collected, the deposit may be irradiated with radiation resonant with the other isotope and the residual material enriched in the one isotope may be evaporated from the substrate and collected

  14. Stable isotopes

    International Nuclear Information System (INIS)

    Brazier, J.L.; Guinamant, J.L.

    1995-01-01

    According to the progress which has been realised in the technology of separating and measuring isotopes, the stable isotopes are used as preferable 'labelling elements' for big number of applications. The isotopic composition of natural products shows significant variations as a result of different reasons like the climate, the seasons, or their geographic origins. So, it was proved that the same product has a different isotopic composition of alimentary and agriculture products. It is also important in detecting the pharmacological and medical chemicals. This review article deals with the technology, like chromatography and spectrophotometry, adapted to this aim, and some important applications. 17 refs. 6 figs

  15. Isotope separation

    International Nuclear Information System (INIS)

    Bartlett, R.J.; Morrey, J.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

  16. Millennial-scale isotope records from a wide-ranging predator show evidence of recent human impact to oceanic food webs

    DEFF Research Database (Denmark)

    Wiley, A.E.; Ostrom, P.H.; Welch, A.J.

    2013-01-01

    Human exploitation of marine ecosystems is more recent in oceanic than near shore regions, yet our understanding of human impacts on oceanic food webs is comparatively poor. Few records of species that live beyond the continental shelves date back more than 60 y, and the sheer size of oceanic reg...

  17. Des-A-lupane in an East African lake sedimentary record as a new proxy for the stable carbon isotopic composition of C3 plants

    NARCIS (Netherlands)

    van Bree, Loes G.J.; Rijpstra, W. Irene C; Al-Dhabi, N.A.; Verschuren, D.; Sinninghe Damste, J.S.; de Leeuw, J.W.

    2016-01-01

    We studied the high-resolution and well-dated 25,000 year sedimentary record of Lake Challa, a deep tropical crater lake in equatorial East Africa, to explore new proxies for paleoenvironmental and paleohydrological change. Sedimentary biomarker analysis revealed the presence of des-A-triterpenoids

  18. A Comparison of Recent Organic and Inorganic Carbon Isotope Records: Why Do They Covary in Some Settings and Not In Others?

    Science.gov (United States)

    Oehlert, A. M.; Swart, P. K.

    2013-12-01

    Covariance between inorganic and organic δ13C records has been used to determine whether a deposit has been altered by diagenesis, how the dynamics of the global carbon cycle changed during the production of the sediments in the deposit, and also for chronostratigraphic correlations. Although covariant records are observed in the ancient geologic record in a variety of depositional environments, such comparisons are not widely applied to modern deposits where definitive data regarding sediment producers, sea level fluctuations, and changes in the global carbon cycle are available. This study uses paired δ13C records from cores collected by the Ocean Drilling Program from three modern periplatform settings (the Great Bahama Bank, the Great Australian Bight, and the Great Barrier Reef), and two pelagic settings (the Walvis Ridge, and the Madingley Rise). These sites were selected in order to assess the influence of several different environmental factors including; sediment and organic matter producers, sediment mineralogy, margin architecture, sea level oscillations, and sediment transport pathways. In the three periplatform settings, multiple cores arranged in a margin to basin transect were analyzed in order to provide insights into the effects of downslope sediment transport. The preliminary results of this study suggest that sea level oscillations and margin architecture may artificially generate a covarying relationship in periplatform sediments that is unrelated to changes in the global carbon cycle. Furthermore, preliminary results from the Walvis Ridge and the Madingley Rise sediments suggest that the relationship between inorganic and organic δ13C records may not always exhibit a positive covariance as is currently assumed for pelagic carbonates.

  19. Testing Urey's carbonate-silicate cycle using the calcium isotopic composition of sedimentary carbonates

    Science.gov (United States)

    Blättler, Clara L.; Higgins, John A.

    2017-12-01

    Carbonate minerals constitute a major component of the sedimentary geological record and an archive of a fraction of the carbon and calcium cycled through the Earth's surface reservoirs for over three billion years. For calcium, carbonate minerals constitute the ultimate sink for almost all calcium liberated during continental and submarine weathering of silicate minerals. This study presents >500 stable isotope ratios of calcium in Precambrian carbonate sediments, both limestones and dolomites, in an attempt to characterize the isotope mass balance of the sedimentary carbonate reservoir through time. The mean of the dataset is indistinguishable from estimates of the calcium isotope ratio of bulk silicate Earth, consistent with the Urey cycle being the dominant mechanism exchanging calcium among surface reservoirs. The variability in bulk sediment calcium isotope ratios within each geological unit does not reflect changes in the global calcium cycle, but rather highlights the importance of local mineralogical and/or diagenetic effects in the carbonate record. This dataset demonstrates the potential for calcium isotope ratios to help assess these local effects, such as the former presence of aragonite, even in rocks with a history of neomorphism and recrystallization. Additionally, 29 calcium isotope measurements are presented from ODP (Ocean Drilling Program) Site 801 that contribute to the characterization of altered oceanic crust as an additional sink for calcium, and whose distinct isotopic signature places a limit on the importance of this subduction flux over Earth history.

  20. Isotopic and chemical composition of groundwater in the Bolivian Altiplano, present space evolution records hydrologic conditions since 11,000 Yr

    International Nuclear Information System (INIS)

    Coudrain, A.; Talbi, A.; Loubet, M.; Gallaire, R.; Jusserand, C.; Ramirez, E.; Ledoux, E.

    1999-01-01

    The phreatic aquifer of the central Altiplano shows a Cl concentration that increases from 0.5 meq l -1 upstream to 150 meq l -1 downstream. The main outflow process from the aquifer is the upward flow E into the unsaturated zone associated to evaporation close to soil surface. A relation has been established for any arid zone areas on the base of isotopic profiles: E (mm yr -1 ) = 63 Z -1.5 where Z (m) is the water table depth under soil surface. The aquifer under study may have acquired its high chlorine content during last lacustrine phase (Tauca, 12 ka BP). Arguments for this hypothesis are: (i) maximum level of the lake (3780 m) higher than present soil elevation in the area, (ii) same order of salinity in the paleolake and in the more saline groundwater, (iii) weak molar ratio of Li/Cl in saline groundwater and in the Tauca, (iv) modelling of Cl transport over 11,000 years consistent with observed spatial evolution of Cl in groundwater. To this scenario, might be superimposed the assumption of a delay for the convective transfer of salt towards south by the coupled effects of accumulation of salt in the unsaturated zone by evaporation from the aquifer during thousand or so years, and of the subsequent return of this salt downwards to the aquifer during some short rainy periods. The 87 Sr/ 86 Sr, major and trace element compositions of surface and groundwater support this proposed scenario. (author)

  1. Isotopes in environmental research

    International Nuclear Information System (INIS)

    Bowen, G.; Rozanski, K.; Vose, P.

    1990-01-01

    Radioactive and stable isotopes have long been considered a very efficient tool for studying physical and biological aspects of how the global ecosystem functions. Their applications in environmental research are numerous, embracing research at all levels. This article looks at only a few of the approaches to environmental problems that involve the use of isotopes. Special attention is given to studies of the Amazon Basin. Environmental isotopes are very efficient tools in water cycle studies. Tritium, a radioactive tracer, is especially useful in studying dynamics of water movement in different compartments of the hydrosphere, both on the local and global scales. Heavy stable isotopes of hydrogen and oxygen (deuterium and oxygen-18) provide information about steady-state characteristics of the water cycle. Isotope methods, some relatively new, have a major role in site-specific studies. Some indicative examples include: Studying turnover of organic matter. Changes in the carbon-13/carbon-12 isotopic ratio of organic matter were used to determine the respective contributions of organic carbon derived from forest and pasture. Studying biological nitrogen fixation. One of the ways nitrogen levels in soil can be maintained for productivity is by biological nitrogen fixation. Studying nitrogen availability and losses. The experimental use of nitrogen-15 is invaluable for defining losses of soil nitrogen to the atmosphere and to groundwater. Studies can similarly be done with stable and radioactive sulphur isotopes. This article indicates some potential uses of isotopes in environmental research. While the major problem of global climate change has not been specifically addressed here, the clearing of the Amazon forest, one focus of the IAEA's environmental programme, may have serious consequences for the global climate. These include substantial reduction of the amount of latent heat transported to the regions outside the tropics and acceleration of the greenhouse

  2. Mantle and crustal contribution in the genesis of Recent basalts from off-rift zones in Iceland: Constraints from Th, Sr and O isotopes

    Science.gov (United States)

    Sigmarsson, Olgeir; Condomines, Michel; Fourcade, Serge

    1992-05-01

    Along the two volcanic off-rift zones in Iceland, the Sn˦fellsnes volcanic zone (SNVZ) and the South Iceland volcanic zone (SIVZ), geochemical parameters vary regularly along the strike towards the centre of the island. Recent basalts from the SNVZ change from alkali basalts to tholeiites where the volcanic zone reaches the active rift axis, and their 87Sr/ 86Sr and Th/U ratios decrease in the same direction. These variations are interpreted as the result of mixing between mantle melts from two distinct reservoirs below Sn˦fellsnes. The mantle melt would be more depleted in incompatible elements, but with a higher 3He/ 4He ratio ( R/Ra≈ 20) beneath the centre of Iceland than at the tip of the Sn˦fellsnes volcanic zone ( R/Ra≈ 7.5). From southwest to northeast along the SIVZ, the basalts change from alkali basalts to FeTi basalts and quartz-normative tholeiites. The Th/U ratio of the Recent basalts increases and both ( 230Th/ 232Th ) and δ 18O values decrease in the same direction. This reflects an important crustal contamination of the FeTi-rich basalts and the quartz tholeiites. The two types of basalts could be produced through assimilation and fractional crystallization in which primary alkali basaltic and olivine tholeiitic melts 'erode' and assimilate the base of the crust. The increasingly tholeiitic character of the basalts towards the centre of Iceland, which reflects a higher degree of partial melting, is qualitatively consistent with increasing geothermal gradient and negative gravity anomaly. The highest Sr isotope ratio in Recent basalts from Iceland is observed inÖr˦fajökull volcano, which has a 3He/ 4He ratio ( R/Ra≈ 7.8) close to the MORB value, and this might represent a mantle source similar to that of Mauna Loa in Hawaii.

  3. 1.8 billion years of fluid-crust interaction: A zircon oxygen isotope record for the lower crust, western Churchill Province, Canadian Shield

    Science.gov (United States)

    Petts, Duane C.; Moser, Desmond E.; Longstaffe, Frederick J.; Davis, William J.; Stern, Richard A.

    2014-04-01

    The western Churchill Province of the Canadian Shield experienced a prolonged and complex formation history (ca. 4.04 to 1.70 Ga), with evidence for multiple episodes of orogenesis and regional magmatic activity. Here we report on the oxygen isotopic compositions of garnet and zircon recovered from lower crustal xenoliths, which have U-Pb ages between ca. 3.5 and 1.7 Ga. Overall, zircon from four metabasite xenoliths from the Rankin Inlet sample suite have δ18O values ranging from + 5.5 to + 8.6‰. Zircon from three metatonalite/anorthosite xenoliths and five metabasite xenoliths from the Repulse Bay sample suite have δ18O values of + 5.6 to + 8.3‰. High δ18O values (> + 6.0‰) for the oldest igneous zircon cores (ca. 3.5 Ga and 3.0-2.6 Ga) indicate that their metatonalite/anorthosite protolith magmas were generated from, or had assimilated, supracrustal rocks that interacted previously with surface-derived fluids. Igneous zircon cores (ca. 2.9-2.6 Ga) from one metabasite xenolith have δ18O values of + 5.6 to + 6.4‰, which suggests a formation from a mantle-derived basaltic/gabbroic magma. Metamorphic zircon cores (ca. 2.0-1.9 Ga) from one metabasite xenolith commonly have δ18O values between + 6.0 and + 6.3‰, which is indicative of a basalt/gabbro protolith and localized reworking of the lower crust caused by regional-scale plate convergence. The wide range of δ18O values (+ 5.5 to + 8.3‰) for ca. 1.75-1.70 Ga metamorphic zircon rims (identified in all xenoliths) indicates regional transient heating and reworking of mantle- and supracrustal-derived crust, induced by magmatic underplating along the crust-mantle boundary.

  4. Late Neogene benthic stable isotope record of ODP Site 999: Implications for Caribbean paleoceanography, organic carbon burial and the Messininian salinity crisis

    Science.gov (United States)

    Bickert, T.; Haug, G.; Tiedemann, R.

    2003-04-01

    The late Neogene closure of the seaway between the North and South American continents is thought to have caused extensive changes in ocean circulation and Northern Hemisphere climate. The timing and consequences of the emergence of the Isthmus of Panama for the ocean circulation have been addressed in several papers which indicate a marked reorganization of surface and deep ocean circulation starting 4.6 million years ago. However, the biogeographic development of marine faunas and floras on both sides of the Panama Isthmus suggests that the paleoceanographic changes related to the closing of the isthmus started much earlier. Furthermore, the closing history of the Panama Seaway overlaps with the tectonic evolution of other ocean gateways in the late Miocene, especially the closure of the Strait of Gibraltar, which led to a transient isolation of the Mediterranean Sea from the Atlantic Ocean, known as the Messinian Salinity Crisis. We report on epibenthic foraminiferal d18O and d13C and percentage sand records of the carbonate fraction from Caribbean ODP Site 999 (12°44´N, 78° 44´W, water depth 2828 m) spanning the interval from 8.6 to 5.3 Ma. Low epibenthic d13C values and low sand contents indicate a poorly ventilated deep Caribbean throughout the late Miocene. At this time the deep Caribbean was dominated by a nutrient-rich Southern Ocean water mass. A mostly constant d13C gradient between the Caribbean and deep Atlantic records suggests that the fluctuations in d13C reflect rather global changes in d13C of the dissolved inorganic carbon due to varying erosion of organic carbon from terrigenous soils and shelf sediments. The observed 100-ky cyclicity of epibenthic d13C is in well accordance with the variability of the terrigenous input to the equatorial Atlantic as recorded by susceptibility records of the Ceara Rise. However, some gradient changes between 6.8 and 5.6 Ma indicate a poorer ventilation of the deep Atlantic related to a reduced production of

  5. Isotopic separation

    International Nuclear Information System (INIS)

    Castle, P.M.

    1979-01-01

    This invention relates to molecular and atomic isotope separation and is particularly applicable to the separation of 235 U from other uranium isotopes including 238 U. In the method described a desired isotope is separated mechanically from an atomic or molecular beam formed from an isotope mixture utilising the isotropic recoil momenta resulting from selective excitation of the desired isotope species by radiation, followed by ionization or dissociation by radiation or electron attachment. By forming a matrix of UF 6 molecules in HBr molecules so as to collapse the V 3 vibrational mode of the UF 6 molecule the 235 UF 6 molecules are selectively excited to promote reduction of UF 6 molecules containing 235 U and facilitate separation. (UK)

  6. Isotopic separation

    International Nuclear Information System (INIS)

    Chen, C.L.

    1979-01-01

    Isotopic species in an isotopic mixture including a first species having a first isotope and a second species having a second isotope are separated by selectively exciting the first species in preference to the second species and then reacting the selectively excited first species with an additional preselected radiation, an electron or another chemical species so as to form a product having a mass different from the original species and separating the product from the balance of the mixture in a centrifugal separating device such as centrifuge or aerodynamic nozzle. In the centrifuge the isotopic mixture is passed into a rotor where it is irradiated through a window. Heavier and lighter components can be withdrawn. The irradiated mixture experiences a large centrifugal force and is separated in a deflection area into lighter and heavier components. (UK)

  7. Isotopic characterisation of the historical lead deposition record at Glensaugh, an organic-rich, upland catchment in rural N.E. Scotland

    International Nuclear Information System (INIS)

    Farmer, J.G.; Graham, M.C.; Bacon, J.R.; Dunn, S.M.; Vinogradoff, S.I.; MacKenzie, A.B.

    2005-01-01

    As part of a wider investigation of the biogeochemistry and fate of Pb deposited from the atmosphere at Glensaugh, a rural upland catchment in N.E. Scotland, the concentration and isotopic composition of Pb were determined in four thinly sectioned monolith cores (25 cm) of peat collected at altitudes of 426-434 m from different faces of Thorter Hill and in a series of 21 10-cm unsectioned cores of peat and organic-rich soil along a transect from near the top (434 m) to the bottom (224 m) of the catchment. Depth profiles of Pb concentration and 206 Pb/ 207 Pb ratio were similar for the longer cores. Subsurface Pb maxima (238-489 mg kg -1 ) typically occurred below 206 Pb/ 207 Pb minima (1.123-1.134). One core was 210 Pb-dated and had a fairly constant 206 Pb/ 207 Pb value of 1.170 from mid-19th century to ca. 1930, followed by a decline (attributable to the increasing influence of Australian Pb of much lower 206 Pb/ 207 Pb ratio) to 1.134 by the early 1990s, and then a rapid increase to 1.160 by 2002, after the phased withdrawal of leaded petrol. The fluxes of Pb increased from 15 mg m -2 year -1 in the late 19th century to a peak of 60 mg m -2 year -1 ca. 1960, before declining steadily to 3.6 mg m -2 year -1 by the beginning of the 21st century. Some 40% of the anthropogenic Pb in the core had been deposited prior to 1900. The mean anthropogenic Pb inventory of the four longer cores was 7.4±1.5 g m -2 , of which ∼70% occurred in the top 10 cm, in good agreement with the inventories of the shorter cores collected above 400 m. These inventories are higher than those of the industrial central belt of Scotland, probably because of enhanced deposition at altitude. This is consistent with the derived average 210 Pb flux of 198±11 Bq m -2 year -1 , which is twice that of typical UK 210 Pb deposition and the rainfall for the site. The past deposition of Pb at Glensaugh, including that from sources (e.g., smelting, coal combustion) other than leaded petrol, has clearly

  8. A high-resolution paleosecular variation record from Black Sea sediments indicating fast directional changes associated with low field intensities during marine isotope stage (MIS) 4

    Science.gov (United States)

    Nowaczyk, Norbert R.; Jiabo, Liu; Frank, Ute; Arz, Helge W.

    2018-02-01

    A total of nine sediment cores recovered from the Archangelsky Ridge in the SE Black Sea were systematically subjected to intense paleo- and mineral magnetic analyses. Besides 16 accelerator mass spectrometry (AMS) 14C ages available for another core from this area, dating was accomplished by correlation of short-term warming events during the last glacial monitored by high-resolution X-ray fluorescence (XRF) scanning as maxima in both Ca/Ti and K/Ti ratios in Black Sea sediments to the so-called 'Dansgaard-Oeschger events' recognized from Greenland ice cores. Thus, several hiatuses could be identified in the various cores during the last glacial/interglacial cycle. Finally, core sections documenting marine isotope stage (MIS) 4 at high resolution back to 69 ka were selected for detailed analyses. At 64.5 ka, according to obtained results from Black Sea sediments, the second deepest minimum in relative paleointensity during the past 69 ka occurred, with the Laschamp geomagnetic excursion at 41 ka being associated with the lowest field intensities. The field minimum during MIS 4 is associated with large declination swings beginning about 3 ka before the minimum. While a swing to 50°E is associated with steep inclinations (50-60°) according to the coring site at 42°N, the subsequent declination swing to 30°W is associated with shallow inclinations of down to 40°. Nevertheless, these large deviations from the direction of a geocentric axial dipole field (I = 61 °, D = 0 °) still can not yet be termed as 'excursional', since latitudes of corresponding virtual geomagnetic poles (VGP) only reach down to 51.5°N (120°E) and 61.5°N (75°W), respectively. However, these VGP positions at opposite sides of the globe are linked with VGP drift rates of up to 0.2° per year in between. These extreme secular variations might be the mid-latitude expression of a geomagnetic excursion with partly reversed inclinations found at several sites much further North in Arctic

  9. Late holocene climate derived from vegetation history and plant cellulose stable isotope records from the Great Basin of western North America

    International Nuclear Information System (INIS)

    Wigand, P.E.; Hemphill, M.L.; Patra, S.M.

    1994-01-01

    Integration of pollen records, and fossil woodrat midden data recovered from multiple strata of fossil woodrat (Neotoma spp.) dens (middens) in both northern and southern Nevada reveal a detailed paleoclimatic proxy record for the Great Basin during the last 45,000 years in growing detail. Clear, late Holocene climate-linked elevational depressions of plant species' distributions have occurred throughout the Great Basin of up to 200 m below today's and by as much as 1000 m below what they were during the middle Holocene. Horizontal plant range extentions during the Holocene reflecting the final northern most adjustments to Holocene climates range up to several hundred kilometers in the Great Basin. Well documented lags evidenced in the late Holocene response of vegetation communities to increased precipitation indicate reduced effectiveness in the ability of plant communities to assimilate excess precipitation. This resulted in significant runoff that was available for recharge. These responses, although indicating both rapid and dramatic fluctuations of climate for the Holocene, fall far short of the scale of such changes during the late Pleistocene. Extension of these results to Pleistocene woodrat den and pollen data evidence spans lasting several hundred to a thousand or more years during which significantly greater amounts of precipitation would have been available for runnoff or recharge

  10. 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

  11. The marine isotope stage 1-5 cryptotephra record of Tenaghi Philippon, Greece: Towards a detailed tephrostratigraphic framework for the Eastern Mediterranean region

    Science.gov (United States)

    Wulf, Sabine; Hardiman, Mark J.; Staff, Richard A.; Koutsodendris, Andreas; Appelt, Oona; Blockley, Simon P. E.; Lowe, J. John; Manning, Christina J.; Ottolini, Luisa; Schmitt, Axel K.; Smith, Victoria C.; Tomlinson, Emma L.; Vakhrameeva, Polina; Knipping, Maria; Kotthoff, Ulrich; Milner, Alice M.; Müller, Ulrich C.; Christanis, Kimon; Kalaitzidis, Stavros; Tzedakis, Polychronis C.; Schmiedl, Gerhard; Pross, Jörg

    2018-04-01

    The iconic climate archive of Tenaghi Philippon (TP), NE Greece, allows the study of short-term palaeoclimatic and environmental change throughout the past 1.3 Ma. To provide high-quality age control for detailed palaeoclimate reconstructions based on the TP archive, (crypto)tephra studies of a peat core 'TP-2005' have been carried out for the 0-130 ka interval. The results show that the TP basin is ideally positioned to receive tephra fall from both the Italian and Aegean Arc volcanic provinces. Two visible tephra layers, the Santorini Cape Riva/Y-2 (c. 22 ka) and the Campanian Ignimbrite (CI)/Y-5 (c. 39.8 ka) tephras, and six primary cryptotephra layers, namely the early Holocene E1 tephra from the Aeolian Islands (c. 8.3 ka), the Campanian Y-3 (c. 29 ka) and X-6 tephras (c. 109.5 ka), as well as counterpart tephras TM-18-1d (c. 40.4 ka), TM-23-11 (c. 92.4 ka) and TM-33-1a (c. 116.7 ka) from the Lago Grande di Monticchio sequence (southern Italy), were identified along with repeatedly redeposited Y-2 and CI tephra material. Bayesian modelling of the ages of seven of the primary tephra layers, 60 radiocarbon measurements and 20 palynological control points have been applied to markedly improve the chronology of the TP archive. This revised chronology constrains the age of tephra TM-18-1d to 40.90-41.66 cal ka BP (95.4% range). Several tephra layers identified in the TP record form important isochrons for correlating this archive with other terrestrial (e.g., Lago Grande di Monticchio, Sulmona Basin and Lake Ohrid) and marine (e.g., Adriatic Sea core PRAD 1-2 and Aegean Sea core LC21) palaeoclimate records in the Mediterranean region.

  12. Terrestrial mollusc records from Xifeng and Luochuan L9 loess strata and their implications for paleoclimatic evolution in the Chinese Loess Plateau during marine Oxygen Isotope Stages 24-22

    Directory of Open Access Journals (Sweden)

    B. Wu

    2011-04-01

    Full Text Available Marine Isotope Stages 24-22 is a key period of the Mid-Pleistocene Transition, however, its climate variability is still unclear. The coarse-grained loess unit L9, one of the most prominent units in the Chinese loess stratigraphy, yields a high potential terrestrial record of paleoclimatic and paleoenvironmental changes during this period. In this study, two high-resolution terrestrial mollusc records of L9 loess strata from the Xifeng and Luochuan sequences in the Chinese Loess Plateau were analysed. Our mollusc results show that the MIS 24, the early and late parts of MIS 22 were dominated by cold and dry climate. Relatively mild-humid climate occurred in MIS 23 and the middle part of MIS 22. The climatic conditions at Xifeng region were cooler and more unstable compared to Luochuan region. A comparison of mollusc species composition and other proxies of L9 strata (MIS 24-22 with those of L1 loess units (MIS 4-2 indicates that the L9 loess was not deposited under the most severe glacial conditions in Quaternary climate history as suggested in previous studies. Our study shows that climatic conditions in the Loess Plateau during the L9 loess forming period were similar to that of gentle glacials (MIS 24 and MIS 22 and interglacial (MIS 23, as suggested by the marine δ18O record. Three cooling fluctuations occurred at ~930 ka, 900 ka and 880 ka, which might hint to the global "900 ka cooling event". The "900-ka event" in the Loess Plateau does not seem to be a simple long glaciation, but rather several complex climatic fluctuations superposed on a general cooling trend. The uplift of the Tibetan Plateau and the general cooling experienced by the Earth during this period may have resulted in abundant dust sources and increased dust transport capability, as indicated by increased grain size and the mass accumulation rate of L9 loess.

  13. Noncovalent Hydrogen Isotope Effects

    Science.gov (United States)

    Buchachenko, A. L.; Breslavskaya, N. N.

    2018-02-01

    Zero-point energies (ZPE) and isotope effects, induced by intermolecular, noncovalent vibrations, are computed and tested by experimental data. The ZPE differences of H- and D-complexes of water with hydrogen, methane, and water molecules are about 100-300 cal/mol; they result to isotope effects IE of 1.20-1.70. Semi-ionic bonds between metal ions and water ligands in M(H2O) 6 2+ complexes are much stronger; their ZPEs are about 12-14 kcal/mol per molecule and result to IE of 1.9-2.1 at 300 K. Protonated (deuterated) water and biwater exhibit the largest ZPE differences and isotope effects; the latter are 25-28 and 12-13 for water and biwater, respectively. Noncovalent IEs contribute markedly into the experimentally measured effects and explain many anomalous and even magic properties of the effects, such as the dependence of IE on the solvents and on the presence of the third substances, enormously large isotope effects at the mild conditions, the difference between IEs measured in the reactions of individual protiated and deuterated compounds and those measured in their mixture. Noncovalent IEs are not negligible and should be taken into account to make correct and substantiated conclusions on the reaction mechanisms. The kinetic equations are derived for the total isotope effects, which include noncovalent IEs as additive factors.

  14. Isotope methods in hydrology

    International Nuclear Information System (INIS)

    Moser, H.; Rauert, W.

    1980-01-01

    Of the investigation methods used in hydrology, tracer methods hold a special place as they are the only ones which give direct insight into the movement and distribution processes taking place in surface and ground waters. Besides the labelling of water with salts and dyes, as in the past, in recent years the use of isotopes in hydrology, in water research and use, in ground-water protection and in hydraulic engineering has increased. This by no means replaces proven methods of hydrological investigation but tends rather to complement and expand them through inter-disciplinary cooperation. The book offers a general introduction to the application of various isotope methods to specific hydrogeological and hydrological problems. The idea is to place the hydrogeologist and the hydrologist in the position to recognize which isotope method will help him solve his particular problem or indeed, make a solution possible at all. He should also be able to recognize what the prerequisites are and what work and expenditure the use of such methods involves. May the book contribute to promoting cooperation between hydrogeologists, hydrologists, hydraulic engineers and isotope specialists, and thus supplement proven methods of investigation in hydrological research and water utilization and protection wherever the use of isotope methods proves to be of advantage. (orig./HP) [de

  15. 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...

  16. 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.

  17. Isotope laboratories

    International Nuclear Information System (INIS)

    1978-01-01

    This report from the Dutch Ministry of Health is an advisory document concerned with isotope laboratories in hospitals, in connection with the Dutch laws for hospitals. It discusses which hospitals should have isotope laboratories and concludes that as many hospitals as possible should have small laboratories so that emergency cases can be dealt with. It divides the Netherlands into regions and suggests which hospitals should have these facilities. The questions of how big each lab. is to be, what equipment each has, how each lab. is organised, what therapeutic and diagnostic work should be carried out by each, etc. are discussed. The answers are provided by reports from working groups for in vivo diagnostics, in vitro diagnostics, therapy, and safety and their results form the criteria for the licences of isotope labs. The results of a questionnaire for isotope labs. already in the Netherlands are presented, and their activities outlined. (C.F.)

  18. Isotopic chirality

    Energy Technology Data Exchange (ETDEWEB)

    Floss, H.G. [Univ. of Washington, Seattle, WA (United States)

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  19. Isotopic separation

    International Nuclear Information System (INIS)

    Chen, C.L.

    1982-01-01

    A method is described for separating isotopes in which photo-excitation of selected isotope species is used together with the reaction of the excited species with postive ions of predetermined ionization energy, other excited species, or free electrons to produce ions or ion fragments of the selected species. Ions and electrons are produced by an electrical discharge, and separation is achieved through radial ambipolar diffusion, electrostatic techniques, or magnetohydrodynamic methods

  20. Isotope enrichment

    International Nuclear Information System (INIS)

    Lydtin, H-J.; Wilden, R.J.; Severin, P.J.W.

    1978-01-01

    The isotope enrichment method described is based on the recognition that, owing to mass diffusion and thermal diffusion in the conversion of substances at a heated substrate while depositing an element or compound onto the substrate, enrichment of the element, or a compound of the element, with a lighter isotope will occur. The cycle is repeated for as many times as is necessary to obtain the degree of enrichment required

  1. Recent (2008-10) concentrations and isotopic compositions of nitrate and concentrations of wastewater compounds in the Barton Springs zone, south-central Texas, and their potential relation to urban development in the contributing zone

    Science.gov (United States)

    Mahler, Barbara J.; Musgrove, MaryLynn; Herrington, Chris; Sample, Thomas L.

    2011-01-01

    contributing watersheds. An isotopic composition of nitrate (delta nitrogen–15) greater than 8 per mil in many of the samples indicated there was a contribution of nitrate with a biogenic (human and or animal waste, or both) origin. Wastewater compounds measured in routine samples were detected infrequently (3 percent of cases), and concentrations were very low (less than the method reporting level in most cases). There was no correlation between nitrate concentrations and the frequency of detection of wastewater compounds, indicating that wastewater compounds might be undergoing removal during such processes as infiltration through soil. Three potential sources of biogenic nitrate to the contributing zone were considered: septic systems, land application of treated wastewater, and domesticated dogs and cats. During 2001–10, the estimated densities of septic systems and domesticated dogs and cats (number per acre) increased in the watersheds of all five creeks, and the rate of land application of treated wastewater (gallons per day per acre) increased in the watersheds of Barton, Bear, and Onion Creeks. Considering the timing and location of the increases in the three sources, septic systems were considered a likely source of increased nitrate to Bear Creek; land application of treated wastewater a likely source to Barton, Bear, and Onion Creeks; and domestic dogs and cats a potential source principally to Williamson Creek. The results of this investigation indicate that baseline water quality, in terms of nitrate, has shifted upward between 2001 and 2010, even without any direct discharges of treated wastewater to the creeks.

  2. Climate and human impacts on vegetation changes in central Guizhou, China: Carbon and oxygen isotopic records in a stalagmite from Yelang Cave

    Science.gov (United States)

    Lee, T.; Liu, Z.; Li, H.; Shen, C.

    2009-12-01

    High-resolution δ18O and δ13C records of a 13.5-cm long stalagmite from Yelang Cave, 60 km west of Guiyang in the southwestern China, have been established by 750 measurements. With low U (10~40 ppb) and Th (0.01~0.367 ppb), four ICP-MS 230Th/U dates indicate that the upper 5.5 cm part is younger than 1000 years, with clear calcite deposition. Below 6 cm depth where the age suddenly changed from late Holocene to late Pleistocene, the stalagmite shows the deposition alternating between white-pure calcite layers and dark-dirty carbonate layers. The dating samples below 6 cm depth have low U contents (26~41 ppb) but high Th concentrations (10~22 ppb) showing 230Th/U dates ranging from 11 ka to 25 ka with large uncertainties. Based on current chronologies, the δ18O and δ13C records exhibit different features in the late Holocene and late Pleistocene. During the past 1000 yrs (0~5.5 cm), the δ18O ranges from -12.0‰ to -9.0‰ (PDB), containing many 10-100 yrs variations with Δδ18O >1‰. The δ13C during this period varies between -7.4‰ and -1.9‰, showing no correlation with the δ18O. Prior to 10.7 ka (below 6 cm), the δ18O and δ13C strongly co-varied, indicating climatic control on the surface vegetation with wet climates (lighter δ18O) resulting in better vegetation (lighter δ13C). The δ13C during the past 1000 yrs had three long-term increasing trends and a sharp decreasing trend, reflecting human impacts on the surface vegetation. The δ13C increased from about -6‰ at ca. AD 1370 to -3.2‰ around AD 1580, illustrating the first deforestation caused by human activity due to large immigration in Ming Dynasty to the region. The δ13C fluctuated between -4.5‰ and -3.0‰ from AD 1580 to AD 1740, then increased to -2.0‰ around AD 1770 with an opposite δ18O trend. This second deforestation event might be caused a strong immigration in early Qing Dynasty due to mining demand. Karst desertification occurred in the area reflected by heavy δ13C

  3. Contribution to the study of luminous sources for uranium isotope measurements by emission spectrometry; Contribution a l'etude de sources lumineuses destinees au dosage isotopique de l'uranium par spectrometrie d'emission

    Energy Technology Data Exchange (ETDEWEB)

    Leichnam, J P; Capitini, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    After a brief summary of results obtained with different hollow cathode luminous sources, the reasons for which they cannot be more widely used are given: an insufficient luminosity when uranium oxides are used in the cathode hollow; the large amount of sample required when it is metallic; the impossibility of effecting a chemical purification of the sample. Electrode-less discharge tubes excited by high frequency whose qualities (luminosity, stability, rapidity of preparation starting from small amounts of sample in various chemical forms, in particular iron) satisfy the conditions laid down for the measurement of uranium 235 by interferometry are used. Tho production process for such lamps is given together with the method of excitation. Examples of recordings obtained with an interferometer of the 'HYPEAC' type and a small grating spectrometer give an idea of the spectral qualities of these sources. (authors) [French] Apres avoir rappele les resultats obtenus avec differentes sources de lumiere a cathode creuse, on explique les raisons qui limitent leur emploi: brillance trop faible lorsque les oxydes d'uranium sont utilises dans le trou cathodique; trop grande quantite d'echantillon necessaire lorsque celui-ci est sous forme metallique; impossibilite de purifier chimiquement l'echantillon. On a employe des tubes a decharge sans electrode excitee par haute frequence, dont les qualites (brillance, stabilite, rapidite de preparation a partir de faibles quantites d'echantillon se presentant sous des formes chimiques diverses, elimination des impuretes chimiques, en particulier du fer) repondent aux conditions imposees pour le dosage isotopique de l'uranium 235 par interferometrie. On decrit le mode operatoire de fabrication de telles lampes et on rappelle le systeme d'excitation. Des exemples d'enregistrement, obtenus avec un appareil interferometrique 'HYPEAC' et un petit spectrometre a reseau, donnent une idee des qualites spectrales de ces sources. (auteurs)

  4. 2. Workshop 'Isotopes in Nature'. 1

    International Nuclear Information System (INIS)

    1979-11-01

    The workshop was aimed at discussing in detail the following problems: (1) distribution of stable and radioactive isotopes in nature, (2) theoretical and experimental studies of isotopic effects in natural processes, (3) problems of sample preparation and sample measurement in determining the relative abundance of stable isotopes or radioactive isotopes in nature, (4) age estimations of samples from different areas of the geosphere, (5) contributions to the specification of global and regional substance cycles in nature with the aid of isotopic and geochemical studies. 75 summaries are included

  5. Pharmaceuticals labelled with stable isotopes

    International Nuclear Information System (INIS)

    Krumbiegel, P.

    1986-11-01

    The relatively new field of pharmaceuticals labelled with stable isotopes is reviewed. Scientific, juridical, and ethical questions are discussed concerning the application of these pharmaceuticals in human medicine. 13 C, 15 N, and 2 H are the stable isotopes mainly utilized in metabolic function tests. Methodical contributions are given to the application of 2 H, 13 C, and 15 N pharmaceuticals showing new aspects and different states of development in the field under discussion. (author)

  6. Contribution of stable isotope to better understand breastfed infant nutritional status in burkina Faso: Longitudinal study with body composition measurement at one year

    International Nuclear Information System (INIS)

    Coulibaly, Nadine; Zeba, Augustin; Ouedraogo, Jean-Bosco; Somda, Serge Manituo

    2014-01-01

    Full text: Background and objectives: Exclusive breastfeeding for six months, followed by the introduction of appropriate complementary foods and continued breastfeeding, as recommended by the World Health Organization, are cornerstones in infant nutrition. In Burkina Faso, only limited information is available on the quantities of human milk consumed and the time of introduction of other foods into infants’ diets and the effect of feeding practice on the infant’s growth. In this work we analyzed infant’s nutritional status according to their feeding practice. Methods: We used the deuterium oxide (DO) dose-to-the mother technique to measure the human milk intake (HM) as well as the non-milk water intake (non-HM) by the babies at 3, 6, 9 and 12 mo. We also evaluated the infant body composition at 12 mo by giving a dose of DO to the babies in order to determine the fat-free mass (FFM) and the fat mass (FM). Saliva samples were collected from the babies and their mother and the DO enrichment in saliva was analyzed by FTIR. At each period, the anthropometric measurements were done to assess the infant nutritional status at 3,6, 9 and 12 mo according to the WHO standards. Results: The HM was maximum at 3 mo with a mean of 968.1 ml (95%CI = 847.2 ml-1089.1 ml), decreased at 6 mo to 918.4 ml (95%CI = 815.9 ml-1020.8 ml) that didn’t change until 12 mo. The non-HM that was 54.6 ml (95%CI = -12.6 ml-121.7 ml) increased significantly (p = 0.001) to 175.2 ml (95%CI = 100.2 ml-250.4 ml) at 6 mo. Exclusive breastfeeding was 32% at 3 mo and reduced to 16% at 6 mo. Breastfeeding was predominant after 6 mo and the contribution of HM in infant feeding was 80% at 9 mo and 69% at 12 mo. The anthropometric measurement showed that wasting was 1.5% at 3 mo but increase significantly (p = 0.04) to 8.7% at 6 mo. The DO dose to mother confirmed that all of the malnourished infants were not exclusive breastfed. At 9 mo the WHZ<-2 was reduced to 6.8%, but 4.5% of the children were

  7. 15 years in promoting the use of isotopic and nuclear technique for combating land degradation and soil erosion: the contribution of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture

    Science.gov (United States)

    Mabit, Lionel; Toloza, Arsenio; Heng, Lee

    2017-04-01

    The world population will exceed 9 billion by the year 2050 and food production will need to be approximately doubled to meet this crucial demand. Most of this increase will occur in developing countries, where the majority of the population depends on agriculture and their land for their livelihoods. Reports from the Intergovernmental Panel on Climate Change (IPCC) predicted negative impact of climate change, threatening global food security. In addition, the intensification of agricultural activities has increased pressure on land and water resources, resulting in different forms of soil degradation, of which soil erosion and associated sedimentation are worsening. Worldwide economic costs of agricultural soil loss and associated sedimentation downstream have been estimated at US 400 billion per year. As a result of climate change, world average soil erosion is expected to further increase significantly. Adapting to climate change requires agricultural soil and water management practices that make agricultural production systems resilient to drought, floods and land degradation, to enhance the conservation of the natural resource base for sustainable upland farming. These current concerns with ensuring sustainable use and management of agroecosystems create an urgent need for reliable quantitative data on the extent and magnitude of soil resource degradation over several spatial and time scales to formulate sound policies and management measures. Integrated isotopic approaches can help in targeting adapted and effective soil-water conservation measures to control soil degradation and therefore contribute to positive feedback mechanisms to mitigate climate change impact on soil and water resources. Set up 60 years ago as the world's centre for cooperation in the nuclear field, the International Atomic Energy Agency (IAEA) promotes the safe, secure and peaceful use of nuclear technologies. Since the end of the 1990s, the Joint FAO/IAEA Division of Nuclear

  8. Isotopes Project

    International Nuclear Information System (INIS)

    Dairiki, J.M.; Browne, E.; Firestone, R.B.; Lederer, C.M.; Shirley, V.S.

    1984-01-01

    The Isotopes Project compiles and evaluates nuclear structure and decay data and disseminates these data to the scientific community. From 1940-1978 the Project had as its main objective the production of the Table of Isotopes. Since publication of the seventh (and last) edition in 1978, the group now coordinates its nuclear data evaluation efforts with those of other data centers via national and international nuclear data networks. The group is currently responsible for the evaluation of mass chains A = 167-194. All evaluated data are entered into the International Evaluated Nuclear Structure Data File (ENSDF) and are published in Nuclear Data Sheets. In addition to the evaluation effort, the Isotopes Project is responsible for production of the Radioactivity Handbook

  9. Triple oxygen and sulfur isotope analyses of sulfate extracted from voluminous volcanic ashes in the Oligocene John Day Formation: insight into dry climate conditions and ozone contribution to supereruptions

    Science.gov (United States)

    Workman, J.; Bindeman, I. N.; Martin, E.; Retallack, G.; Palandri, J. L.; Weldon, N.

    2014-12-01

    Large volume pyroclastic silicic eruptions emit hundreds of megatons of SO2 into the troposphere and stratosphere that is oxidized into sulfuric acid (H2SO4) by a variety of reactions with mass independent oxygen signatures (MIF), Δ17O>0. Sulfuric acid is then preserved as gypsum in parental volcanic deposits. Diagenic effects are mass dependent and can dilute, but otherwise do not affect MIF ratios. Pleistocene Yellowstone and Bishop tuffs and modern volcanic eruptions preserved under arid climate conditions in North American playa lakes, preserve small amounts of volcanic sulfate as gypsum. This gypsum's Δ17O>0, in combination with isotopic variations of δ18O, δ33S and δ34S is distinct from sedimentary sulfate and reveals its original MIF sulfate isotopic signal and the effect of super eruptions on the atmosphere, and ozone consumption in particular. We use linear algebraic equations to resolve volcanic versus sedimentary (MIF=0) sources. We have found that many large volume ignimbrites have very high initial Δ17O in volcanic sulfate that can only be acquired from reaction with stratospheric ozone. We here investigate nine thick (>2 m) ash beds ranging in age from ~33-23 Ma in the John Day Formation of central Oregon, including massive 28.6 Ma Picture Gorge tuff of newly identified Crooked River supercaldera. The 28.6 Ma Picture Gorge tuff (PGT) has the highest measured Δ17O of 3.5‰, and other tuffs (Tin Roof, Biotite, Deep Creek) have +1.3 to 3.4‰ Δ17O excesses. Sulfate from modern smaller tropospheric eruptions studied for comparison have a resolvable 0.4‰ range consistent with liquid-phase based H2O2 oxidation. The PGT is coeval with the ignimbrite flare-up in western N. America, the 28-29 Ma eruption of the 5000 km3 Fish Canyon tuff and the 28 Ma Never Summer Field eruption in Nebraska-Colorado that have the highest measured Δ17O of 6‰ (Bao et al. 2003). We speculate on the climatic/atmospheric effects of these multiple ~28 Ma supereruptions

  10. Isotope production

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Dewi M.

    1995-07-15

    Some 2 0% of patients using radiopharmaceuticals receive injections of materials produced by cyclotrons. There are over 200 cyclotrons worldwide; around 35 are operated by commercial companies solely for the production of radio-pharmaceuticals with another 25 accelerators producing medically useful isotopes. These neutron-deficient isotopes are usually produced by proton bombardment. All commonly used medical isotopes can be generated by 'compact' cyclotrons with energies up to 40 MeV and beam intensities in the range 50 to 400 microamps. Specially designed target systems contain gram-quantities of highly enriched stable isotopes as starting materials. The targets can accommodate the high power densities of the proton beams and are designed for automated remote handling. The complete manufacturing cycle includes large-scale target production, isotope generation by cyclotron beam bombardment, radio-chemical extraction, pharmaceutical dispensing, raw material recovery, and labelling/packaging prior to the rapid delivery of these short-lived products. All these manufacturing steps adhere to the pharmaceutical industry standards of Good Manufacturing Practice (GMP). Unlike research accelerators, commercial cyclotrons are customized 'compact' machines usually supplied by specialist companies such as IBA (Belgium), EBCO (Canada) or Scanditronix (Sweden). The design criteria for these commercial cyclotrons are - small magnet dimensions, power-efficient operation of magnet and radiofrequency systems, high intensity extracted proton beams, well defined beam size and automated computer control. Performance requirements include rapid startup and shutdown, high reliability to support the daily production of short-lived isotopes and low maintenance to minimize the radiation dose to personnel. In 1987 a major step forward in meeting these exacting industrial requirements came when IBA, together with the University of Louvain-La-Neuve in Belgium, developed the Cyclone-30

  11. Assessing methane oxidation under landfill covers and its contribution to the above atmospheric CO2 levels: The added value of the isotope (δ13C and δ18O CO2; δ13C and δD CH4) approach

    International Nuclear Information System (INIS)

    Widory, D.; Proust, E.; Bellenfant, G.; Bour, O.

    2012-01-01

    Highlights: ► Comparison of the isotope and mass balance approaches to evaluate the level of methane oxidation within a landfill. ► The level of methane oxidation is not homogenous under the landfill cover and is strongly correlated to the methane flux. ► Isotope tracking of the contribution of the methane oxidation to the CO 2 concentrations in the ambient air. - Abstract: We are presenting here a multi-isotope approach (δ 13 C and δ 18 O of CO 2 ; δ 13 C and δD of CH 4 ) to assess (i) the level(s) of methane oxidation during waste biodegradation and its migration through a landfill cover in Sonzay (France), and (ii) its contribution to the atmospheric CO 2 levels above the surface. The isotope approach is compared to the more conventional mass balance approach. Results from the two techniques are comparable and show that the CH 4 oxidation under the landfill cover is heterogenous, with low oxidation percentages in samples showing high biogas fluxes, which was expected in clay covers presenting fissures, through which CH 4 is rapidly transported. At shallow depth, more immobile biogas pockets show a higher level of CH 4 oxidation by the methanotrophic bacteria. δ 13 C of CO 2 samples taken at different heights (from below the cover up to 8 m above the ground level) were also used to identify and assess the relative contributions of its main sources both under the landfill cover and in the surrounding atmosphere.

  12. Isotopically modified compounds

    International Nuclear Information System (INIS)

    Kuruc, J.

    2009-01-01

    In this chapter the nomenclature of isotopically modified compounds in Slovak language is described. This chapter consists of following parts: (1) Isotopically substituted compounds; (2) Specifically isotopically labelled compounds; (3) Selectively isotopically labelled compounds; (4) Non-selectively isotopically labelled compounds; (5) Isotopically deficient compounds.

  13. Isotope generator

    International Nuclear Information System (INIS)

    1979-01-01

    The patent describes an isotope generator incorporating the possibility of stopping elution before the elution vessel is completely full. Sterile ventilation of the whole system can then occur, including of both generator reservoir and elution vessel. A sterile, and therefore pharmaceutically acceptable, elution fluid is thus obtained and the interior of the generator is not polluted with non-sterile air. (T.P.)

  14. Normalization of oxygen and hydrogen isotope data

    Science.gov (United States)

    Coplen, T.B.

    1988-01-01

    To resolve confusion due to expression of isotopic data from different laboratories on non-corresponding scales, oxygen isotope analyses of all substances can be expressed relative to VSMOW or VPDB (Vienna Peedee belemnite) on scales normalized such that the ??18O of SLAP is -55.5% relative to VSMOW. H3+ contribution in hydrogen isotope ratio analysis can be easily determined using two gaseous reference samples that differ greatly in deuterium content. ?? 1988.

  15. Canada's isotope crisis : what next?

    International Nuclear Information System (INIS)

    Nathwani, J.; Wallace, D.

    2010-01-01

    Canada urgently requires a rigorous debate on the strategic options for ensuring a robust, reliable, and affordable supply of radioactive isotopes. Should the debate be confined to how Canada can best develop the necessary technologies solely for our own use or should Canada abandon the idea of producing its own isotope supply and any future aspirations to serve the global market? Canada's Isotope Crisis focuses on the central policy question: do we dare to try to shape the future or do we retreat into silence because we are not prepared to make the necessary investments for the future well-being of Canadians? This volume showcases pointed essays and analysis from members of the academy and individuals who have made contributions to the development of medical isotopes and pioneered their use in medical practice. It also includes commentary from those involved in the production, manufacturing, processing, and distribution of isotopes. Canada's Isotope Crisis is a multi-disciplinary effort that addresses the global dimension of isotope supply and combines expert opinions on the present and past with knowledge of the relevant government agencies and the basis for their decisions at critical junctures.

  16. Introduction to the special issue of "Loess and Climatic Record": Memory of Professor Liu Tungsheng for his scientific contributions and his centenary birthday

    Science.gov (United States)

    Ding, Zhongli; Derbyshire, Edward; Sun, Jimin

    2018-04-01

    This special issue is to memory Professor Liu Tungsheng for his scientific contributions and his centenary birthday. Liu Tungsheng was the former President of the International Association for Quaternary Association (INQUA), and the Honorary President of the Chinese Association for Quaternary Research (CHIQUA). Liu's best known contribution to Quaternary research is his pioneering and systematic study of the extensive loess deposits of China, which has been regarded as the best terrestrial paleoclimatic archive on the Earth. He won many international awards including the Tyler Prize for Environmental Achievement in 2002 and the Alexander von Humboldt Medal in 2007. He was an inspiring leader, one of China's, and indeed one of the world's most outstanding Earth scientists. This introduction aims to explore the personal factors behind his great achievements and reviews the papers included in this special issue from his colleagues, friends, and students.

  17. Isotope hydrology

    International Nuclear Information System (INIS)

    Drost, W.

    1978-01-01

    The International Symposium on Isotope Hydrology was jointly organized by the IAEA and UNESCO, in co-operation with the National Committee of the Federal Republic of Germany for the International Hydrological Programme (IHP) and the Gesellschaft fuer Strahlen- und Umweltforschung mbH (GSF). Upon the invitation of the Federal Republic of Germany the Symposium was held from 19-23 June 1978 in Neuherberg on the GSF campus. The Symposium was officially opened by Mr. S. Eklund, Director General of the IAEA. The symposium - the fifth meeting held on isotope hydrology - was attended by over 160 participants from 44 countries and four international organizations and by about 30 observers from the Federal Republic of Germany. Due to the absence of scientists from the USSR five papers were cancelled and therefore only 46 papers of the original programme were presented in ten sessions

  18. Cost-benefit assessment of using electronic health records data for clinical research versus current practices: Contribution of the Electronic Health Records for Clinical Research (EHR4CR) European Project.

    Science.gov (United States)

    Beresniak, Ariel; Schmidt, Andreas; Proeve, Johann; Bolanos, Elena; Patel, Neelam; Ammour, Nadir; Sundgren, Mats; Ericson, Mats; Karakoyun, Töresin; Coorevits, Pascal; Kalra, Dipak; De Moor, Georges; Dupont, Danielle

    2016-01-01

    The widespread adoption of electronic health records (EHR) provides a new opportunity to improve the efficiency of clinical research. The European EHR4CR (Electronic Health Records for Clinical Research) 4-year project has developed an innovative technological platform to enable the re-use of EHR data for clinical research. The objective of this cost-benefit assessment (CBA) is to assess the value of EHR4CR solutions compared to current practices, from the perspective of sponsors of clinical trials. A CBA model was developed using an advanced modeling approach. The costs of performing three clinical research scenarios (S) applied to a hypothetical Phase II or III oncology clinical trial workflow (reference case) were estimated under current and EHR4CR conditions, namely protocol feasibility assessment (S1), patient identification for recruitment (S2), and clinical study execution (S3). The potential benefits were calculated considering that the estimated reduction in actual person-time and costs for performing EHR4CR S1, S2, and S3 would accelerate time to market (TTM). Probabilistic sensitivity analyses using Monte Carlo simulations were conducted to manage uncertainty. Should the estimated efficiency gains achieved with the EHR4CR platform translate into faster TTM, the expected benefits for the global pharmaceutical oncology sector were estimated at €161.5m (S1), €45.7m (S2), €204.5m (S1+S2), €1906m (S3), and up to €2121.8m (S1+S2+S3) when the scenarios were used sequentially. The results suggest that optimizing clinical trial design and execution with the EHR4CR platform would generate substantial added value for pharmaceutical industry, as main sponsors of clinical trials in Europe, and beyond. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Erosion of the Alps: use of Rb-Sr isotopic data from molassic sediments to identify the ages of the metamorphism recorded by the eroded rocks; Erosion des Alpes: histoire metamorphique des roches erodees par l`analyse du couple Rb-Sr des sediments molassiques

    Energy Technology Data Exchange (ETDEWEB)

    Henry, P; Deloule, E [Centre National de la Recherche Scientifique (CNRS), 54 - Nancy (France). Centre de Recherches Petrographiques et Geochimiques; Michard, A [Aix-Marseille-3 Univ., 13 - Marseille (France)

    1994-06-01

    Rb-Sr isotopic data from Oligocene and Miocene peri-alpine molassic sediments allow us to identify the different periods for which the eroded rocks have or have not recorded an alpine metamorphism. The Chattian and the Burdigalian sediments result from the erosion of rocks for which the latest metamorphic event was variscan, while the Stampian, Aquitanian and ``Helvetian`` sediments show evidence for the erosion of rocks which have recorded alpine metamorphic events. The application of this method to old detrital sediments could permit determination of the ages of the tectonic events which occurred in the sediment source regions. (authors). 18 refs., 6 figs.

  20. Isotope shift studies in gadolinium spectra

    International Nuclear Information System (INIS)

    Ahmad, S.A.; Saksena, G.D.; Venugopalan, A.

    1976-01-01

    Isotope shift studies have been carried out in the gadolinium spectrum using a recording Fabry-Perot spectrometer and gadolinium samples enriched in 156 Gd and 160 Gd isotopes. Isotope shifts Δsigma(156-160) have been recorded in 134 lines in the region 3930-4140 A. Some of these lines involve the recently identified even configuration 4f 8 5d6s of Gd I and the newly classified transition 4f 8 6s-4f 8 6p of Gd II. From the isotope shift measurements of lines involving the 4f 8 6s-4f 8 6p transition in Gd II, the isotope shift, ΔT(156-160)=87 mK, has been obtained for the 4f 8 6s configuration. Electronic configurations have been suggested for a number of energy levels and configuration mixing has been pointed out in certain cases. (Auth.)

  1. Seasonal variability of iodine and selenium in surface and groundwater as a factor that may contribute to iodine isotope balance in the thyroid gland and its irradiation in case of radioiodine contamination during accidents at the NPP

    Science.gov (United States)

    Korobova, Elena; Kolmykova, Lyudmila; Ryzhenko, Boris; Berezkin, Viktor; Saraeva, Anastasia

    2016-04-01

    Radioiodine release to the environment during the accident at the Chernobyl NPP led to the increased risk of the thyroid cancer cases within the contaminated areas, the effect being aggravated in conditions of stable iodine and selenium deficiency in local food chains. Although the drinking water iodine is usually believed to contribute not more than 10% to local diet, our estimations accounting of water content in other products and several regional studies (e.g. India and Australia) proved its portion to be at least twice as much. As radioiodine isotopes are short-lived, their absorption depends greatly on stable iodine and selenium sufficiency in thyroid gland in the first few days of contamination and seasonal variation of stable iodine and selenium in local sources of drinking water may be significant as modifying the resulting thyroid irradiation in different seasons of the year. The main goal of the study was to evaluate seasonal variation of levels of iodine and selenium in natural waters of the Bryansk region as a possible factor affecting the radioiodine intake by thyroid gland of animals and humans in case of radioiodine contamination during the accident. Seasonal I and Se concentration was measured in the years of 2014 and 2015 at 14 test points characterizing surface (river and lake) and drinking groundwater. Obtained data proved considerable seasonal variation of I and Se concentration in natural waters (3,7-8,1 μg/l and 0,04-0,4 μg/l respectively) related to physico-chemical water parameters, such as pH, Eh and fluctuations in concentration of dissolved organic matter. The widest I and Se seasonal variability was observed in surface and well waters, maximum I level being found in autumn at the end of vegetation period characterized by active I leaching from the decomposed organic residues by long lasting precipitations. The content of selenium in the surface waters during summer-autumn (0,06-0,3 μg/l) was higher than in spring (0,04-0,05

  2. Isotope diagnostics apparatus

    International Nuclear Information System (INIS)

    Herrschaft, H.

    1976-01-01

    The invention relates to a measuring probe for an isotope diagnostics apparatus to determine the distribution of radioactive substances in a body by measuring the radiation emanating from this body by means of a multiplicity of measuring probes directed simultaneously towards areas of measuring surfae and carried in guidances of a holding block. The measuring results of the individual probes are recorded separately, thus allowing the possibility of being evaluated separately, too. Measuring probes of this kind are used in multi-channel measuring objects and are useful particularly for determining the regional cerebral blood flow. (orig./ORU) [de

  3. Radiocarbon analysis in an Alpine ice core: record of anthropogenic and biogenic contributions to carbonaceous aerosols in the past (1650–1940

    Directory of Open Access Journals (Sweden)

    T. M. Jenk

    2006-01-01

    Full Text Available Long-term concentration records of carbonaceous particles (CP are of increasing interest in climate research due to their not yet completely understood effects on climate. Nevertheless, only poor data on their concentrations and sources before the 20th century are available. We present a first long-term record of organic carbon (OC and elemental carbon (EC concentrations – the two main fractions of CP – along with the corresponding fraction of modern carbon (fM derived from radiocarbon (14C analysis in ice. This allows a distinction and quantification of natural (biogenic and anthropogenic (fossil sources in the past. CP were extracted from an ice archive, with resulting carbon quantities in the microgram range. Analysis of 14C by accelerator mass spectrometry (AMS was therefore highly demanding. We analysed 33 samples of 0.4 to 1 kg ice from a 150.5 m long ice core retrieved at Fiescherhorn glacier in December 2002 (46°33'3.2" N, 08°04'0.4" E; 3900 m a.s.l.. Samples were taken from bedrock up to the firn/ice transition, covering the time period 1650–1940 and thus the transition from the pre-industrial to the industrial era. Before ~1850, OC was approaching a purely biogenic origin with a mean concentration of 24 μg kg−1 and a standard deviation of 7 μg kg−1. In 1940, OC concentration was about a factor of 3 higher than this biogenic background, almost half of it originating from anthropogenic sources, i.e. from combustion of fossil fuels. The biogenic EC concentration was nearly constant over the examined time period with 6 μg kg−1 and a standard deviation of 1 μg kg−1. In 1940, the additional anthropogenic input of atmospheric EC was about 50 μg kg−1.

  4. Isotopic tools for protecting the seas

    International Nuclear Information System (INIS)

    Kinley, D. III

    2006-01-01

    The oceans and seas are our greatest natural resource, providing us with much of the food we eat and the air we breathe. More than US $900 billion per year of the world's economy is directly tied to ocean-based activities such as fishing, coastal tourism and shipping, and the oceans and seas contribute greatly to the broad ecological balance of our planet. Yet numerous human activities are mounting a growing threat to the health and sustainability of the marine environment. Coral reefs around the world are suffering a rapid decline. Fish stocks are increasingly overexploited, and some unsustainable commercial fish farming is destroying marine habitats. Pollution of the ocean is extensive and, in some cases, irreversible. And our greatest guarantee against global warming - the ocean's vast ability to act as a carbon sink - may be seriously undermined. Protection of the oceans and seas against further deterioration requires scientific investigation to better understand and manage the principal processes. It is here that the use of radionuclides and stable isotopes, which have been used for about 50 years as investigative tools, comes into its own. They have been used to study environmental processes, fate of contaminants in ecosystems, atmosphere-ocean interactions, surface and groundwater systems and the response of atmospheric, hydrological and marine systems to climate change. Coastal zones, supporting about 60% of the global population, require special attention because of their contribution to the world's food supply and their sensitivity to pollution. Nuclear and isotopic techniques provide tools for addressing on a quantitative basis the problems of coastal zone management, including investigation of contamination, groundwater - seawater interactions and other adverse impacts such as salt-water intrusion. One of the most important parameters in determining the climate on Earth is the temperature record of the ocean. It is believed that surface seawater

  5. Application of Fe Isotopes to the Search for Life and Habitable Planets

    Science.gov (United States)

    Johnson, Clark M.; Beard, Brian L.; Nealson, Kenneth L.

    2001-01-01

    The relatively new field of Fe isotope geochemistry can make important contributions to tracing the geochemical cycling of Fe, which bears on issues such as metabolic processing of Fe, surface redox conditions, and development of planetary atmospheres and biospheres. It appears that Fe isotope fractionation in nature and the lab spans about 4 per mil (%) in Fe-56/Fe-54, and although this range is small, our new analytical methods produce a precision of +/- 0.05% on sample sizes as small as 100 ng (10(exp -7) g); this now provides us with a sufficient "signal-to-noise" ratio to make this isotope system useful. We review our work in three areas: 1) the terrestrial and lunar rock record, 2) experiments on inorganic fractionation, and 3) experiments involving biological processing of Fe. Additional information is contained in the original extended abstract.

  6. Contribution to the knowledge of cotylean flatworms (Turbellaria, Polycladida) from Iranian coasts: Introducing a new species, with remarks on new records.

    Science.gov (United States)

    Maghsoudlou, Abdolvahab; Rahimian, Hassan

    2014-09-08

    Very little information is available regarding marine free-living flatworms not only from Iran, but throughout the countries surrounding the Persian Gulf and the Gulf of Oman. The present study first introduces a new euryleptid species, and then reports four pseudocerotid polyclads which inhabit Iranian shallow rocky shores of the Persian Gulf and the Gulf of Oman. Maritigrella makranica sp. nov. is characterized dorsally by a medial cream or white reticulated appearance containing pale orange spots in a honeycomb pattern, a distinct orange submarginal band around the entire body margin and between the marginal tentacles, black spots scattered around mid-dorsal surface, becoming more sparse on raised median region and towards body margin, surrounded by a dark-grey halo around the body midline and orange-black halo towards margin. Three of the four pseudocerotids species belonging to the genera Pseudobiceros Faubel, 1984; Pseudoceros Lang, 1884; and Thysanozoon Grube, 1840, are new records for the studied areas, while the other has been reported in the Persian Gulf previously. Comments on Iranian species are provided and associations of flatworms with ascidians and sponges were observed. 

  7. Self-Tracking, Social Media and Personal Health Records for Patient Empowered Self-Care. Contribution of the IMIA Social Media Working Group.

    Science.gov (United States)

    Paton, C; Hansen, M; Fernandez-Luque, L; Lau, A Y S

    2012-01-01

    This paper explores the range of self-tracking devices and social media platforms used by the self-tracking community, and examines the implications of widespread adoption of these tools for scientific progress in health informatics. A literature review was performed to investigate the use of social media and self-tracking technologies in the health sector. An environmental scan identified a range of products and services which were used to exemplify three levels of self-tracking: self-experimentation, social sharing of data and patient controlled electronic health records. There appears to be an increase in the use of self-tracking tools, particularly in the health and fitness sector, but also used in the management of chronic diseases. Evidence of efficacy and effectiveness is limited to date, primarily due to the health and fitness focus of current solutions as opposed to their use in disease management. Several key technologies are converging to produce a trend of increased personal health surveillance and monitoring, social connectedness and sharing, and integration of regional and national health information systems. These trends are enabling new applications of scientific techniques, from personal experimentation to e-epidemiology, as data gathered by individuals are aggregated and shared across increasingly connected healthcare networks. These trends also raise significant new ethical and scientific issues that will need to be addressed, both by health informatics researchers and the communities of self-trackers themselves.

  8. Further contributions to the Hydradephaga (Coleoptera, Haliplidae, Gyrinidae and Dytiscidae) fauna of Prince Edward Island, Canada: new records, distributions and faunal composition.

    Science.gov (United States)

    Alarie, Yves

    2016-01-01

    The Haliplidae, Gyrinidae and Dytiscidae (Coleoptera) of Prince Edward Island, Canada were surveyed during the years 2004-2005. A total of 2450 individuals from 79 species were collected from 98 different localities, among which 30 species are newly recorded from that region. Among these, Acilius sylvanus Hilsenhoff, Rhantus consimilis Motschulsky and Neoporus sulcipennis (Fall) stand out as representing the easternmost reports of these species in Canada. Once removed, Gyrinus aquiris LeConte (Gyrinidae) is reinstated in the faunal list of Prince Edward Island. According to this study and literature 84 species of Hydradephaga are currently known from Prince Edward Island. The Nearctic component of the fauna is made up of 68 species (80.9%) and the Holarctic component of 16 species (19.1%). Most species are characteristic of the Boreal and Atlantic Maritime Ecozones and have a transcontinental distribution. In an examination of the Hydradephaga of insular portions of Atlantic Canada, we found that despite significantly different land areas and different distances to the neighbouring continental mainland the island faunas of Prince Edward Island and insular Newfoundland are very similar in the number of species (84 and 94 species respectively) despite differences in composition. With a land area significantly larger than that of Prince Edward Island, however, the fauna of Cape Breton Island was 39% smaller consisting of 53 species. This difference could be due to the comparative lack of collecting efforts on Cape Breton Island.

  9. Integration of ice-core, marine and terrestrial records for the Australian Last Glacial Maximum and Termination: a contribution from the OZ INTIMATE group

    Science.gov (United States)

    Turney, C. S. M.; Haberle, S.; Fink, D.; Kershaw, A. P.; Barbetti, M.; Barrows, T. T.; Black, M.; Cohen, T. J.; Corrège, T.; Hesse, P. P.; Hua, Q.; Johnston, R.; Morgan, V.; Moss, P.; Nanson, G.; van Ommen, T.; Rule, S.; Williams, N. J.; Zhao, J.-X.; D'Costa, D.; Feng, Y.-X.; Gagan, M.; Mooney, S.; Xia, Q.

    2006-10-01

    The degree to which Southern Hemisphere climatic changes during the end of the last glacial period and early Holocene (30-8 ka) were influenced or initiated by events occurring in the high latitudes of the Northern Hemisphere is a complex issue. There is conflicting evidence for the degree of hemispheric teleconnection and an unresolved debate as to the principle forcing mechanism(s). The available hypotheses are difficult to test robustly, however, because the few detailed palaeoclimatic records in the Southern Hemisphere are widely dispersed and lack duplication. Here we present climatic and environmental reconstructions from across Australia, a key region of the Southern Hemisphere because of the range of environments it covers and the potentially important role regional atmospheric and oceanic controls play in global climate change. We identify a general scheme of events for the end of the last glacial period and early Holocene but a detailed reconstruction proved problematic. Significant progress in climate quantification and geochronological control is now urgently required to robustly investigate change through this period. Copyright

  10. 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....

  11. Modeling the carbon isotope composition of bivalve shells (Invited)

    Science.gov (United States)

    Romanek, C.

    2010-12-01

    The stable carbon isotope composition of bivalve shells is a valuable archive of paleobiological and paleoenvironmental information. Previous work has shown that the carbon isotope composition of the shell is related to the carbon isotope composition of dissolved inorganic carbon (DIC) in the ambient water in which a bivalve lives, as well as metabolic carbon derived from bivalve respiration. The contribution of metabolic carbon varies among organisms, but it is generally thought to be relatively low (e.g., 90%) in the shells from terrestrial organisms. Because metabolic carbon contains significantly more C-12 than DIC, negative excursions from the expected environmental (DIC) signal are interpreted to reflect an increased contribution of metabolic carbon in the shell. This observation contrasts sharply with modeled carbon isotope compositions for shell layers deposited from the inner extrapallial fluid (EPF). Previous studies have shown that growth lines within the inner shell layer of bivalves are produced during periods of anaerobiosis when acidic metabolic byproducts (e.g., succinic acid) are neutralized (or buffered) by shell dissolution. This requires the pH of EPF to decrease below ambient levels (~7.5) until a state of undersaturation is achieved that promotes shell dissolution. This condition may occur when aquatic bivalves are subjected to external stressors originating from ecological (predation) or environmental (exposure to atm; low dissolved oxygen; contaminant release) pressures; normal physiological processes will restore the pH of EPF when the pressure is removed. As a consequence of this process, a temporal window should also exist in EPF at relatively low pH where shell carbonate is deposited at a reduced saturation state and precipitation rate. For example, EPF chemistry should remain slightly supersaturated with respect to aragonite given a drop of one pH unit (6.5), but under closed conditions, equilibrium carbon isotope fractionation

  12. 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

  13. A novel methodology to investigate isotopic biosignatures

    Science.gov (United States)

    Horner, T. J.; Lee, R. B. Y.; Henderson, G. M.; Rickaby, R. E. M.

    2012-04-01

    An enduring goal of trace metal isotopic studies of Earth History is to find isotopic 'fingerprints' of life or of life's individual physiochemical processes. Generally, such signatures are sought by relating an isotopic effect observed in controlled laboratory conditions or a well-characterized environment to a more complex system or the geological record. However, such an approach is ultimately limited because life exerts numerous isotopic fractionations on any one element so it is hard to dissect the resultant net fractionation into its individual components. Further, different organisms, often with the same apparent cellular function, can express different isotopic fractionation factors. We have used a novel method to investigate the isotopic fractionation associated with a single physiological process-enzyme specific isotopic fractionation. We selected Cd isotopes since only one biological use of Cd is known, CdCA (a Cd/Zn carbonic anhydrase from the coastal diatom T. Weissflogii). Thus, our investigation can also inform the long standing mystery as to why this generally toxic element appears to have a nutrient-like dissolved isotopic and concentration profile in the oceans. We used the pET-15b plasmid to insert the CdCA gene into the E. coli genome. There is no known biochemical function for Cd in E. coli, making it an ideal vector for studying distinct physiological processes within a single organism. The uptake of Cd and associated isotopic fractionation was determined for both normal cells and those expressing CdCA. It was found that whole cells always exhibited a preference for the light isotopes of Cd, regardless of the expression of CdCA; adsorption of Cd to cell surfaces was not seen to cause isotopic fractionation. However, the cleaning procedure employed exerted a strong control on the observed isotopic composition of cells. Using existing protein purification techniques, we measured the Cd isotopic composition of different subcellular fractions of E

  14. Natural isotopes

    International Nuclear Information System (INIS)

    Vogel, J.C.

    1986-01-01

    14 C dates between 600 and 900 AD were obtained for early Iron Age sites in Natal, and from 1300 to 1450 AD for rock engraving sites in Bushmanland. Palaeoenvironmental data derived from the dating of samples related to sedimentary and geomorphic features in the central and northern Namib Desert enabled the production of a tentative graph for the changes in humidity in the region over the past 40000 years. These results suggest that relatively humid conditions came to an end in the Namib at ±25000 BP (before present). The increased precision of the SIRA mass spectrometer enabled the remeasurement of 13 C and 18 O in the Cango stalagmite. This data confirmed that the environmental temperatures in the Southern Cape remained constant to within ±1 o C during the past 5500 years. Techniques and applications for environmental isotopes in hydrology were developed to determine the origin and movement of ground water. Isotopic fractionation effects in light elements in nature were investigated. The 15 N/ 14 N ratio in bones of animals and humans increases in proportion to the aridity of the environment. This suggests that 15 N in bone from dated archaeological sites could be used to detect changes in past climatic conditions as naturally formed nitrate minerals are higly soluble and are only preserved in special, very dry environments. The sources and sinks of CO 2 on the South African subcontinent were also determined. The 13 C/ 12 C ratios of air CO 2 obtained suggest that the vegetation provides the major proportion of respired CO 2 . 9 refs., 1 fig

  15. Stable isotope studies

    International Nuclear Information System (INIS)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs

  16. Method for separating isotopes

    International Nuclear Information System (INIS)

    Jepson, B.E.

    1975-01-01

    Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether

  17. Study of groundwater recharge in Rechna Doab using isotope techniques

    International Nuclear Information System (INIS)

    Sajjad, M.I.; Tasneem, M.A.; Ahmed, M.; Hussain, S.D.; Khan, I.H.; Akram, W.

    1992-04-01

    Isotopic studies were performed in the Rechna Doab area to understand the recharge mechanism, investigate the relative contributions from various sources such as rainfall, rivers and canal system and to estimate the turn over times and replenishment rate of groundwater. The isotopic data suggest that the groundwater in the project area can be divided into different zones each having its own characteristic isotopic composition. The enriched isotopic values show rain recharge and depleted isotopic values are associated with river/canal system while the intermediate isotopic values show a mixing of two or more sources of water. The major contribution, however, comes from canal system. The isotopic data suggest that there is no quick movement of groundwater in the area. 18 figs. (author)

  18. Stable isotopes and diet of hunters gatherers of southwest of Buenos Aires province (Argentina)

    International Nuclear Information System (INIS)

    Scabuzzo, Clara; Frontini, Romina; Vecchi, Rodrigo; Bayon, Cristina

    2016-01-01

    Results of the first stable isotopes analysis (δ""1"3C and δ"1"5N) of archaeological sites located in the southwest of the province of Buenos Aires (Argentina) are presented. Both the construction of an isotopic ecology and prehistoric human diets of the sector are explored. The isotopic ecology indicates diverse environments in which marine animals have enriched δ"1"3C col. values; while terrestrial species such as coypo, greater rhea and large-sized herbivores have the poorest values that are indistinguishable among the different taxa. Furthermore, ducks and a hairy armadillo showed intermediate values. Human isotopic values indicate a diet based on the consumption of meat. These proteins came predominantly from terrestrial animals complemented by marine resources. The local archaeological record is consistent with this information, as the main faunal resources are terrestrial species; nevertheless a scarce representation of marine fauna, mainly Otariids, is registered. In this paper we present the first isotopic values for the studied area and thus it is a preliminary contribution that must be further investigated with new samples

  19. The Use of Isotope Techniques to Separate of Hydrography Components. Case Study: Ankara-Guvenc Basin

    International Nuclear Information System (INIS)

    Tekeli, Y.I.; Sorman, A.U.; Sayin, M.

    2002-01-01

    In this research, a stable environmental isotope study was carried out from analysis of water samples collected from rainfall, runoff (total discharge), springs (subsurface flows), and wells (ground waters)in Ankara-Guevenc basin having a drainage area of about 16.125 km 2 between 1996-2000. The aim of the study was to investigate the rainfall-runoff relationship for the basin. Recorded total ten discharge hydrographs are separated to their components using stable isotopes (Oxygen-18, Deuterium) contents. Among these samples, unit hydrographs from two one-peak storm hydrographs were derived using both isotope and graphical methods, and the derived unit hydrographs values including peaks were compared. Peak values of 10 and 20 minutes unit hydrographs of the basin derived by using isotope method (Q p = 1322 1/s and Q p = 1327 l/s) are compared with those of graphical method (Q p = 1656 1/s, and Q p = 1250 1/s) using Barnes semi-log approach. It was found out that, the contribution of subsurface flow which is component of total discharge hydrograph and originating from various sub layers are important in the total flow of basin using isotope method of approach

  20. Method for separating isotopes

    International Nuclear Information System (INIS)

    Jepson, B.E.

    1976-01-01

    The invention comprises a method for separating different isotopes of elements from each other by contacting a feed solution containing the different isotopes with a macrocyclic polyether to preferentially form a macrocyclic polyether complex with the lighter of the different isotopes. The macrocyclic polyether complex is then separated from the lighter isotope depleted feed solution. A chemical separation of isotopes is carried out in which a constant refluxing system permits a continuous countercurrent liquid-liquid extraction. (LL)

  1. Method for separating isotopes

    International Nuclear Information System (INIS)

    Schlenker, R.F.

    1978-01-01

    A vortex tube for separating isotopes is described. A gas mixture containing the isotopic molecules enters the vortex tube under pressure and is separated into a hot discharge flow stream and a cold discharge flow stream. The hot discharge is enriched in lighter isotopic molecules whereas the cold discharge flow stream is enriched in the heavier isotopic molecules. The vortex tube can be used in a single stage or multistage isotope separation apparatus

  2. The first steps of isotope hydrology

    International Nuclear Information System (INIS)

    Moser, H.

    1995-01-01

    The author narrated on his personal experience of the past forty years of the development of isotope hydrology as an independent scientific branch. He started with the basic research work of for example Dansgaard and Libby and went on to the recent world-wide recording and interpreting isotopic data network. The IAEA organisation has accompanied the scientific development in an exemplary manner and, thus brought forward the isotope hydrological research activities to the high standard reached presently. This is documented by the great number of publications promoted by the IAEA throughout this time. 4 figs, 24 refs

  3. 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.

  4. Isotope angiocardiography. Method and preliminary own studies

    Energy Technology Data Exchange (ETDEWEB)

    Stepinska, J; Ruzyllo, W; Konieczny, W [Centrum Medyczne Ksztalcenia Podyplomowego, Warsaw (Poland)

    1979-01-01

    Method of technetium isotope 99 m pass through the heart recording with the aid of radioisotope scanner connected with seriograph and computer is being presented. Preliminary tests were carried out in 26 patients with coronary disease without or with previous myocardial infarction, cardiomyopathy, ventricular septal defect and in patients with artificial mitral and aortic valves. The obtained scans were evaluated qualitatively and compared with performed later contrast X-rays of the heart. Size of the right ventricle, volume and rate of left atrial evacuation, size and contractability of left ventricle were evaluated. Similarity of direct and isotope angiocardiographs, non-invasional character and repeatability of isotope angiocardiography advocate its usefulness.

  5. 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

  6. Identification of historical lead sources in roof dust and recent lake sediments from an industrialized are: Indications from lead isotopes

    International Nuclear Information System (INIS)

    Chenhall, B.E.; Depers, A.M.; Jones, B.G.; Chiaradia, M.

    1997-01-01

    X-ray fluorescence and stable lead (Pb) isotopic analyses have been undertaken on dusts, known from microscopic investigation to contain significant quantities of industrially- and urban-derived particulate matter, present in the roof cavities of houses in the Illawarra region (N.S.W., Australia), with the objective of examining the historic record of Pb pollution. All investigated houses contained in excess of 250 μg g -1 Pb, with dwellings close to a copper smelter, in a large industrial complex including a major steelworks, containing higher (>2500 μg g -1 ) Pb concentrations. The isotopic composition in the dusts, expressed here as 206 Pb/ 204 Pb, is relatively constant at 17.0, irrespective of dwelling age or distance from the industrial complex. Contamination of the dusts by Pb sourced from paint cannot explain the isotopic uniformity of the dust samples. Isotopic modelling indicates that the dusts contain Pb derived from the copper smelter, gasoline-air Pb and a minor contribution from the steelworks. Isotopic calculations, together with records of particulate pollution emission, indicate a link between the Pb in roof dusts and Pb contamination of the near surface lagoonal sediments. Over the last five decades, atmospheric fallout of Pb-bearing particulate matter appears to have been the dominant pathway for addition of Pb to the lagoon and dwellings in the Illawarra region

  7. New aragonite 87Sr/86Sr records of Mesozoic ammonoids and approach to the problem of N, O, C and Sr isotope cycles in the evolution of the Earth

    Science.gov (United States)

    Zakharov, Yuri D.; Dril, Sergei I.; Shigeta, Yasunari; Popov, Alexander M.; Baraboshkin, Eugenij Y.; Michailova, Irina A.; Safronov, Peter P.

    2018-02-01

    New Sr isotope data from well-preserved aragonite ammonoid shell material from the Mesozoic are compared with that from a living Nautilus shell. The prominent negative Sr isotope excursions known from the Middle Permian, Jurassic and Cretaceous probably have their origins in intensive plate tectonic activity, followed by enhanced hydrothermal activity at the mid-ocean ridges (mantle volcanism) which supplied low radiogenic Sr to seawater. The maximum positive (radiogenic) shift in the lower Mesozoic Sr isotope curve (Lower Triassic peak) was likely caused by a significant expansion of dry land surfaces (Dabie-Sulu Triassic orogeny) and their intensive silicate weathering in conditions of extreme warming and aridity in the very end of the Smithian, followed by warm and humid conditions in the late Spathian, which apparently resulted in a significant oceanic input of radiogenic Sr through riverine flux. The comparatively high 87Sr/86Sr ratio obtained from the living Nautilus shell is probably a function of both the Alpine orogeny, which was accompanied by significant continental weathering and input of radiogenic Sr to the oceans, and the weakening of mantle volcanism.

  8. Stable-isotope paleoclimatology

    International Nuclear Information System (INIS)

    Deuser, W.G.

    1978-01-01

    Seasonal variations of temperature and salinity in the surface waters of large parts of the oceans are well established. Available data on seasonal distributions of planktonic foraminifera show that the abundances of different species groups peak at different times of the year with an apparent succession of abundance peaks through most of the year. This evidence suggests that a measure of seasonal contrast is recorded in the isotope ratios of oxygen, and perhaps carbon, in the tests of different foraminiferal species. The evaluation of this potential paleoclimatologic tool awaits planned experiments with recent foraminifera in well-known settings, but a variety of available data is consistent with the idea that interspecies differences in 18 O content contain a seasonal component.(auth.)

  9. Isotopes in environmental studies - Aquatic Forum 2004. Proceedings of an international conference. Unedited papers

    International Nuclear Information System (INIS)

    2006-01-01

    A better understanding of key processes in the aquatic environment, responsible for its future development and its protection, were at the forefront of the IAEA's International Conference on Isotopes in Environmental Studies - AQUATIC FORUM 2004 convened in Monaco from 25 to 29 October 2004, which was the most important gathering of the year of isotope environmental scientists. Over 320 experts from 60 IAEA Member States and 6 international organizations delivered 185 oral presentations in 6 plenary and 31 parallel sessions and made 130 poster presentations. The conference reviewed the present state of the art isotopic methods for investigation of the aquatic environment. The main conference subjects considered were: (i) behaviour, transport and distribution of isotopes in the aquatic environment; (ii) climate change studies using isotopic records in the marine environment; (iii) groundwater dynamics, modelling and management of freshwater sources; (iv) important global projects, such as WOCE, WOMARS, SHOTS, GEOTRACES; (v) joint IAEA-UNESCO submarine groundwater investigations in the Mediterranean Sea, the Southwest Atlantic and Pacific Oceans; (vi) new trends in radioecological investigations, concentrating on the protection of marine biota against radioactive contamination; (vii) transfers in analytical technologies from bulk analyses to particle and compound specific analyses of environmental samples; (viii) development of new isotopic techniques, such as AMS and ICPMS, and their successful applications in environmental studies; and many other exciting topics which were presented and discussed during the Conference. Four workshops were held simultaneously: - ATOMS-Med Workshop - development of a project proposal for oceanographic investigations in the Eastern Mediterranean. - El Nino - Research Co-ordination Meeting of the new IAEA Coordinated Research Project investigating climate change using isotopic records in the marine environment. - CELLAR Workshop

  10. Absolute isotopic abundances of Ti in meteorites

    International Nuclear Information System (INIS)

    Niederer, F.R.; Papanastassiou, D.A.; Wasserburg, G.J.

    1985-01-01

    The absolute isotope abundance of Ti has been determined in Ca-Al-rich inclusions from the Allende and Leoville meteorites and in samples of whole meteorites. The absolute Ti isotope abundances differ by a significant mass dependent isotope fractionation transformation from the previously reported abundances, which were normalized for fractionation using 46 Ti/ 48 Ti. Therefore, the absolute compositions define distinct nucleosynthetic components from those previously identified or reflect the existence of significant mass dependent isotope fractionation in nature. We provide a general formalism for determining the possible isotope compositions of the exotic Ti from the measured composition, for different values of isotope fractionation in nature and for different mixing ratios of the exotic and normal components. The absolute Ti and Ca isotopic compositions still support the correlation of 50 Ti and 48 Ca effects in the FUN inclusions and imply contributions from neutron-rich equilibrium or quasi-equilibrium nucleosynthesis. The present identification of endemic effects at 46 Ti, for the absolute composition, implies a shortfall of an explosive-oxygen component or reflects significant isotope fractionation. Additional nucleosynthetic components are required by 47 Ti and 49 Ti effects. Components are also defined in which 48 Ti is enhanced. Results are given and discussed. (author)

  11. Isotope puzzle in sputtering

    International Nuclear Information System (INIS)

    Zheng Liping

    1998-01-01

    Mechanisms affecting multicomponent material sputtering are complex. Isotope sputtering is the simplest in the multicomponent materials sputtering. Although only mass effect plays a dominant role in the isotope sputtering, there is still an isotope puzzle in sputtering by ion bombardment. The major arguments are as follows: (1) At the zero fluence, is the isotope enrichment ejection-angle-independent or ejection-angle-dependent? (2) Is the isotope angular effect the primary or the secondary sputter effect? (3) How to understand the action of momentum asymmetry in collision cascade on the isotope sputtering?

  12. The Global Network of Isotopes in Precipitation after 55 years: assessing past, present and future developments

    Science.gov (United States)

    Terzer, Stefan; Araguas-Araguas, Luis; Wassenaar, Leonard I.; Aggarwal, Pradeep K.

    2015-04-01

    The Global Network of Isotopes in Precipitation (GNIP) is a global observation programme operated by the International Atomic Energy Agency (IAEA), in cooperation with the World Meteorological Organization (WMO) and more than 100 contributing institutions worldwide. GNIP has been the primary repository for baseline stable (δ18O, δ2H) and radioactive (3H) isotope data since its foundation in 1960. The impetus for GNIP was the monitoring of radioactive fallout from atmospheric thermonuclear testing and resulting tritium levels of precipitation, but tritium together with stable isotopes was recognized as a key to understanding hydrological processes. Later, new applications were developed focusing on hydrometeorology and paleoclimatic research. Increasingly, GNIP data are being used more widely in ecological and forensic investigations, e.g. for tracking of migratory animals. The GNIP database comprises more than 135,000 isotopic records (δ18O: 63,000; δ2H: 55,000; 3H: 63,000) of monthly composite precipitation samples from more than 1,000 stations worldwide. About 300 stations are currently active for stable isotopes and ca. 100 for tritium. Data for most of the active stations is available up to 2013. Several national isotopic observation networks (e.g. in Austria, Australia, China or the United States of America) exist besides GNIP, complementing precipitation isotope data at national levels. The spatially and temporally discrete nature of the GNIP dataset induces coverage gaps. Recently, highly-resolved gridded datasets were established to help overcome this deficiency through geostatistical prediction models. These 'isoscape' (isotopic landscapes) are based on combinations of multiple regression and interpolation methods, with a range of parameterization available at regional and global levels. Attempts to bridge the gap between 'one-size-fits-all' global parameterization and improved predictions at regional and local levels led to the establishment of a

  13. Carbon dioxide effects research and assessment program. Proceedings of the International Meeting on Stable Isotopes in Tree-Ring Research, New Paltz, New York, May 22-25, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Jacoby, G [ed.

    1980-12-01

    Information about the past and present concentrations of CO/sub 2/ in the atmosphere and variations in climate can be obtained from measurements of stable isotopes in tree rings; specifically carbon-13, oxygen-18 and deuterium. The analysis of these stable isotopes in tree rings is a relatively new and rapidly developing field. This proceedings volume contains most of the papers presented at the meeting. The first paper gives an overview of the status of carbon-13 research. Papers relating to carbon-13 are in section I and grouped separately from the contributions on carbon-14. Although the meeting was primarily concerned with stable isotopes, all carbon isotopic analysis may be helpful in understanding the carbon-13 record in tree rings. The papers on hydrogen and oxygen isotope studies are in sections II and III respectively. The remaining sections contain papers that consider more than one isotope at a time, general topics related to isotopes, atmospheric changes and tree growth, and methods of isotopic analysis.

  14. Isotopically exchangeable phosphorus

    International Nuclear Information System (INIS)

    Barbaro, N.O.

    1984-01-01

    A critique revision of isotope dilution is presented. The concepts and use of exchangeable phosphorus, the phosphate adsorption, the kinetics of isotopic exchange and the equilibrium time in soils are discussed. (M.A.C.) [pt

  15. Optical isotope shifts for unstable samarium isotopes

    International Nuclear Information System (INIS)

    Eastham, D.A.; Walker, P.M.; Griffith, J.A.R.; Evans, D.E.; Grant, I.S.; England, J.G.; Fawcett, M.J.

    1984-01-01

    Using a tunable dye laser beam intersecting a thermal atomic beam, optical isotope shifts and hyperfine splittings have been measured for the four unstable samarium isotopes between 144 Sm and 154 Sm, covering the well known transition region from spherical to deformed shapes. (orig.)

  16. Isotopic tools for protecting the seas

    International Nuclear Information System (INIS)

    Verlini, G.; Osvath I.; Razmjoo, M.

    2009-09-01

    The oceans and seas are our greatest natural resource, providing us with much of the food we eat and the air we breathe. More than US $900 billion per year of the world's economy is directly tied to ocean-based activities such as fishing, coastal tourism and shipping, and the oceans and seas contribute greatly to the broad ecological balance of our planet. Yet numerous human activities are mounting a growing threat to the health and sustainability of the marine environment. Coral reefs around the world are suffering a rapid decline. Fish stocks are increasingly overexploited, and some unsustainable commercial fish farming is destroying marine habitats. Pollution of the ocean is extensive and, in many cases, irreversible. And our greatest guarantee against global warming - the ocean's vast ability to act as a carbon sink - may be seriously undermined. Protection of the oceans and seas against further deterioration requires scientific investigation to better understand and manage the principal processes. It is here that the use of radionuclides and stable isotopes, which have been used for about 50 years as investigative tools, comes into its own. They have been used to study environmental processes, the fate of contaminants in ecosystems, atmosphere-ocean interactions, surface and groundwater systems and the response of atmospheric, hydrological and marine systems to climate change. Coastal zones, supporting about 60% of the global population, require special attention because of their contribution to the world's food supply and their sensitivity to pollution. Nuclear and isotopic techniques provide tools for addressing on a quantitative basis the problems of coastal zone management, including investigation of contamination, groundwater-seawater interactions and other adverse impacts such as salt-water intrusion. One of the most important parameters in determining the climate on Earth is the temperature record of the ocean. It is believed that surface seawater

  17. The 2-nd Conference on Isotopic and Molecular Processes. Abstracts

    International Nuclear Information System (INIS)

    Bogdan, Mircea

    2001-01-01

    The proceedings of the 2-nd Conference on Isotopic and Molecular Processes held on September 27 - 29, 2001 in Cluj - Napoca, Romania, contains contributions presented as: 11 plenary lectures, 24 oral presentations and 103 posters in two sections, namely, isotopic processes and molecular processes. The main topics treated in this conference were isotope production, separation and enrichment as well as stable isotope applications. Also, studies on isotope effects in different fields are reported. Besides reports on isotope effects, exchange and separation, new methods of preparation and labelling compounds used particularly in nuclear medicine are presented. Environmental studies by means of stable isotope and radon monitoring are described. Applications of radiation effects and different nuclear methods in medicine are also addressed

  18. Stable isotope (δ"1"3C and δ"1"5N) based interpretation of organic matter source and paleoenvironmental conditions in Al-Azraq basin, Jordan

    International Nuclear Information System (INIS)

    Ahmad, Khaldoun; Davies, Caroline

    2017-01-01

    This study examines the stable isotopes of carbon and nitrogen from cored lacustrine sediments of the Al-Azraq, an arid lake basin on the Jordan Plateau. Lacustrine sediments contain valuable records of paleoenvironmental conditions, recording local and regional responses to environmental change. Previous paleo-reconstructions on the Jordan Plateau are based on archaeology, pollen, mineralogy, and stratigraphy. The application of organic geochemistry analyses to these lake sediments identifies multiple sources of organic matter, biological production, and contributes to understanding the paleoenvironments of the Al-Azraq basin during the mid-Pleistocene period. Organic carbon concentration (Corg) provides an overview of the organic matter distribution. Carbon isotopic composition (δ13Corg) and nitrogen isotopic composition (δ15N) are indicators of organic matter sources and paleoproductivity. Magnetic susceptibility (MGSUS) measured the concentration of ferromagnetic minerals and indicated aeolian inputs. Organic geochemistry differentiated five paleoenvironmental zones with specific sources of organic matter, both aquatic and terrestrial. It identified a long period of climate wetter than the present, punctuated by a short intense period of aridity. Diagenesis plays an important role in the decomposition of organic matter and studies indicate this degradation can alter the isotopic signals of organic matter. Analyses of the isotopic signals and statistical analyses demonstrate diagenesis is not a factor in the Al-Azraq sediments in all but Zone 4 of the paleoenvironmental zones. This Zone is defined by less negative carbon isotopic composition and the presence of thick primary gypsum layers, in addition to the influx of high peaks of aeolian sediment as reflected in the magnetic susceptibility data. Stable isotope geochemistry provides detailed information on the paleoenvironments of lake sediments, and is applicable to typically challenging arid basin sediments

  19. Multiple stable isotope fronts during non-isothermal fluid flow

    Science.gov (United States)

    Fekete, Szandra; Weis, Philipp; Scott, Samuel; Driesner, Thomas

    2018-02-01

    develop in kinetically limited systems, which propagates with the advection speed of the incoming fluid and is, therefore, traveling fastest. The results show that oxygen isotope signatures at thermal fronts recorded in rocks and veins that experienced isotope exchange with fluids can easily be misinterpreted, namely if bulk analytical techniques are applied. However, stable isotope microanalysis on precipitated minerals may - if later isotope exchange is kinetically limited - provide a valuable archive of the transient thermal and hydrological evolution of a system.

  20. Geochemistry of silicon isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Tiping; Li, Yanhe; Gao, Jianfei; Hu, Bin [Chinese Academy of Geological Science, Beijing (China). Inst. of Mineral Resources; Jiang, Shaoyong [China Univ. of Geosciences, Wuhan (China).

    2018-04-01

    Silicon is one of the most abundant elements in the Earth and silicon isotope geochemistry is important in identifying the silicon source for various geological bodies and in studying the behavior of silicon in different geological processes. This book starts with an introduction on the development of silicon isotope geochemistry. Various analytical methods are described and compared with each other in detail. The mechanisms of silicon isotope fractionation are discussed, and silicon isotope distributions in various extraterrestrial and terrestrial reservoirs are updated. Besides, the applications of silicon isotopes in several important fields are presented.

  1. Applications of stable isotopes

    International Nuclear Information System (INIS)

    Letolle, R.; Mariotti, A.; Bariac, T.

    1991-06-01

    This report reviews the historical background and the properties of stable isotopes, the methods used for their measurement (mass spectrometry and others), the present technics for isotope enrichment and separation, and at last the various present and foreseeable application (in nuclear energy, physical and chemical research, materials industry and research; tracing in industrial, medical and agronomical tests; the use of natural isotope variations for environmental studies, agronomy, natural resources appraising: water, minerals, energy). Some new possibilities in the use of stable isotope are offered. A last chapter gives the present state and forecast development of stable isotope uses in France and Europe

  2. Oxygen isotope ratios in the shell of Mytilus edulis: archives of glacier meltwater in Greenland?

    DEFF Research Database (Denmark)

    Versteegh, E. A. A.; Blicher, Martin E.; Mortensen, J.

    2012-01-01

    Melting of the Greenland Ice Sheet (GrIS) is accelerating and will contribute significantly to global sea level rise during the 21st century. Instrumental data on GrIS melting only cover the last few decades, and proxy data extending our knowledge into the past are vital for validating models...... predicting the influence of ongoing climate change. We investigated a potential meltwater proxy in Godthåbsfjord (West Greenland), where glacier meltwater causes seasonal excursions with lower oxygen isotope water (δ18Ow) values and salinity. The blue mussel (Mytilus edulis) potentially records...... its potential as a palaeo-meltwater proxy. First, we confirmed that M. edulis shell calcite oxygen isotope (δ18Oc) values are in equilibrium with ambient water and generally reflect meltwater conditions. Subsequently we investigated if this species recorded the full range of δ18Ow values occurring...

  3. Deglacial Western Equatorial Pacific pCO2 Reconstruction Using Boron Isotopes of Planktonic Foraminiferas

    Science.gov (United States)

    Kubota, K.; Yokoyama, Y.; Ishikawa, T.; Sagawa, T.; Ikehara, M.; Yamazaki, T.

    2017-12-01

    During the last deglaciation (ca. 19 - 11 ka), partial pressure of CO2 (pCO2) of the atmosphere increased by 80 μatm. Many paleoceanographers point out that the ocean had played an important role in atmospheric CO2 rise, since the ocean have 60 times larger capacity to store carbon compared to the atmosphere. However, evidence on where carbon was transferred from the ocean to the atmosphere is still lacking, hampering our understanding of global carbon cycles in glacial-interglacial timescales. Boron isotope of skeletons of marine calcifying organisms such as corals and foraminiferas can pin down where CO2 source/sink existed, because boron isotopes of marine calcium carbonates is dependent on seawater pH, from which pCO2 of the past seawater can be reconstructed. In previous studies using the boron isotope teqnique, Martinez-Boti et al. (2015, Nature) and Kubota et al. (2014, Scientific Reports) revealed that central and eastern parts of the equatorial Pacific acted as a CO2 source (i.e., CO2 emission) during the last deglaciation, suggesting the equatorial Pacific's contribution to atmospheric CO2 rise. However, some conflicting results have been confirmed in a marine sediment record from the western part of the equatorial Pacific (Palmer & Pearson, 2003, Science), making the conclusion elusive. In this presentation, we will show new results of Mg/Ca, oxygen isotope, and boron isotope measurements during the last 35 ka on two species of surface dwelling foraminiferas (Globigerinoides ruber and G. sacculifer) which was hand-picked separatedly from a well-dated marine sediment core recovered from the West Caroline Basin (KR05-15 PC01) (Yamazaki et al., 2008, GRL). From the new records, we will discuss how the equatorial Pacific behaved during the last deglaciation and how it related to the global carbon cycles.

  4. Clumped-isotope geochemistry of carbonates: A new tool for the reconstruction of temperature and oxygen isotope composition of seawater

    Energy Technology Data Exchange (ETDEWEB)

    Bernasconi, Stefano M., E-mail: Stefano.bernasconi@erdw.ethz.ch [Geological Institute, ETH Zuerich, Sonneggstrasse 5, 8092 Zuerich (Switzerland); Schmid, Thomas W.; Grauel, Anna-Lena [Geological Institute, ETH Zuerich, Sonneggstrasse 5, 8092 Zuerich (Switzerland); Mutterlose, Joerg [Institut fuer Geologie, Mineralogie und Geophysik, Ruhr Universitaet Bochum, Universitaetsstr. 150, 44801 Bochum (Germany)

    2011-06-15

    Highlights: > Clumped-isotope thermometry of carbonates is discussed. > Clumped isotopes of Belemnites show higher sea surface temperatures than commonly assumed for the lower Cretaceous. > The potential of clumped-isotope measurement on foraminifera is discussed. - Abstract: Clumped-isotope geochemistry deals with State of ordering of rare isotopes in molecules, in particular with their tendency to form bonds with other rare isotopes rather than with the most abundant ones. Among its possible applications, carbonate clumped-isotope thermometry is the one that has gained most attention because of the wide potential of applications in many disciplines of the earth sciences. In particular, it allows reconstructing the temperature of formation of carbonate minerals without knowledge of the isotopic composition of the water from which they were formed. In addition, the O isotope composition of the waters from which they were formed can be calculated using the {delta}{sup 18}O of the same carbonate sample. This feature offers new approaches in paleoclimatology for reconstructing past global geochemical cycles. In this contribution two applications of this method are presented. First the potential of a new analytical method of measurement of clumped isotopes on small samples of foraminifera, for high-resolution SST and seawater {delta}{sup 18}O reconstructions from marine sediments is shown. Furthermore the potential of clumped isotope analysis of belemnites, for reconstructing seawater {delta}{sup 18}O and temperatures in the Cretaceous is shown.

  5. The production of cosmogenic isotopes in the earth's atmosphere and their inventories

    International Nuclear Information System (INIS)

    O'Brien, K.; de la Zerda Lerner, A.; Shea. M.A.; Smart, D.F.

    1991-01-01

    In this paper, production rates of cosmogenic isotopes in the Earth's atmosphere and their dependence on solar modulation and geomagnetic field intensity are calculated. Spallation cross sections were also obtained using the Silberberg-Tsao equations and solar modulation effects were calculated using the force-field model. The current geomagnetic field is treated in detail, and past magnetic fields are modeled based on the archeomagnetic record. Radiocarbon and radioberyllium inventories so obtained are in good agreement with current values. The neutrino-emitting radioactivity of the Earth's atmosphere is shown to add a negligible contribution to the flux from the Sun

  6. Lagrangian process attribution of isotopic variations in near-surface water vapour in a 30-year regional climate simulation over Europe

    Science.gov (United States)

    Dütsch, Marina; Pfahl, Stephan; Meyer, Miro; Wernli, Heini

    2018-02-01

    Stable water isotopes are naturally available tracers of moisture in the atmosphere. Due to isotopic fractionation, they record information about condensation and evaporation processes during the transport of air parcels, and therefore present a valuable means for studying the global water cycle. However, the meteorological processes driving isotopic variations are complex and not very well understood so far, in particular on short (hourly to daily) timescales. This study presents a Lagrangian method for attributing the isotopic composition of air parcels to meteorological processes, which provides new insight into the isotopic history of air parcels. It is based on the temporal evolution of the isotope ratios, the humidity, the temperature, and the location of the air parcels. Here these values are extracted along 7-day backward trajectories started every 6 hours from near the surface in a 30-year regional climate simulation over Europe with the isotope-enabled version of the model of the Consortium for Small-Scale Modelling (COSMOiso). The COSMOiso simulation has a horizontal resolution of 0.25° and is driven at the lateral boundaries by a T106 global climate simulation with the isotope-enabled version of the European Centre Hamburg model (ECHAMwiso). Both simulations are validated against measurements from the Global Network of Isotopes in Precipitation (GNIP), which shows that nesting COSMOiso within ECHAMwiso improves the representation of δ2H and deuterium excess in monthly accumulated precipitation. The method considers all isotopic changes that occur inside the COSMOiso model domain, which, on average, correspond to more than half of the mean and variability in both δ2H and deuterium excess at the air parcels' arrival points. Along every trajectory, the variations in the isotope values are quantitatively decomposed into eight process categories (evaporation from the ocean, evapotranspiration from land, mixing with moister air, mixing with drier air

  7. Lagrangian process attribution of isotopic variations in near-surface water vapour in a 30-year regional climate simulation over Europe

    Directory of Open Access Journals (Sweden)

    M. Dütsch

    2018-02-01

    Full Text Available Stable water isotopes are naturally available tracers of moisture in the atmosphere. Due to isotopic fractionation, they record information about condensation and evaporation processes during the transport of air parcels, and therefore present a valuable means for studying the global water cycle. However, the meteorological processes driving isotopic variations are complex and not very well understood so far, in particular on short (hourly to daily timescales. This study presents a Lagrangian method for attributing the isotopic composition of air parcels to meteorological processes, which provides new insight into the isotopic history of air parcels. It is based on the temporal evolution of the isotope ratios, the humidity, the temperature, and the location of the air parcels. Here these values are extracted along 7-day backward trajectories started every 6 hours from near the surface in a 30-year regional climate simulation over Europe with the isotope-enabled version of the model of the Consortium for Small-Scale Modelling (COSMOiso. The COSMOiso simulation has a horizontal resolution of 0.25° and is driven at the lateral boundaries by a T106 global climate simulation with the isotope-enabled version of the European Centre Hamburg model (ECHAMwiso. Both simulations are validated against measurements from the Global Network of Isotopes in Precipitation (GNIP, which shows that nesting COSMOiso within ECHAMwiso improves the representation of δ2H and deuterium excess in monthly accumulated precipitation. The method considers all isotopic changes that occur inside the COSMOiso model domain, which, on average, correspond to more than half of the mean and variability in both δ2H and deuterium excess at the air parcels' arrival points. Along every trajectory, the variations in the isotope values are quantitatively decomposed into eight process categories (evaporation from the ocean, evapotranspiration from land, mixing with moister air, mixing

  8. Pyroxene Homogenization and the Isotopic Systematics of Eucrites

    Science.gov (United States)

    Nyquist, L. E.; Bogard, D. D.

    1996-01-01

    The original Mg-Fe zoning of eucritic pyroxenes has in nearly all cases been partly homogenized, an observation that has been combined with other petrographic and compositional criteria to establish a scale of thermal "metamorphism" for eucrites. To evaluate hypotheses explaining development of conditions on the HED parent body (Vesta?) leading to pyroxene homogenization against their chronological implications, it is necessary to know whether pyroxene metamorphism was recorded in the isotopic systems. However, identifying the effects of the thermal metamorphism with specific effects in the isotopic systems has been difficult, due in part to a lack of correlated isotopic and mineralogical studies of the same eucrites. Furthermore, isotopic studies often place high demands on analytical capabilities, resulting in slow growth of the isotopic database. Additionally, some isotopic systems would not respond in a direct and sensitive way to pyroxene homogenization. Nevertheless, sufficient data exist to generalize some observations, and to identify directions of potentially fruitful investigations.

  9. A Novel Framework for Quantifying past Methane Recycling by Sphagnum-Methanotroph Symbiosis Using Carbon and Hydrogen Isotope Ratios of Leaf Wax Biomarkers

    Science.gov (United States)

    Nichols, Jonathan E.; Isles, Peter D. F.; Peteet, Dorothy M.

    2014-01-01

    The concentration of atmospheric methane is strongly linked to variations in Earth's climate. Currently, we can directly reconstruct the total atmospheric concentration of methane, but not individual terms of the methane cycle. Northern wetlands, dominated by Sphagnum, are an important contributor of atmospheric methane, and we seek to understand the methane cycle in these systems. We present a novel method for quantifying the proportion of carbon Sphagnum assimilates from its methanotrophic symbionts using stable isotope ratios of leaf-wax biomarkers. Carbon isotope ratios of Sphagnum compounds are determined by two competing influences, water content and the isotope ratio of source carbon. We disentangled these effects using a combined hydrogen and carbon isotope approach. We constrained Sphagnum water content using the contrast between the hydrogen isotope ratios of Sphagnum and vascular plant biomarkers. We then used Sphagnum water content to calculate the carbon isotope ratio of Sphagnum's carbon pool. Using a mass balance equation, we calculated the proportion of recycled methane contributed to the Sphagnum carbon pool, 'PRM.' We quantified PRM in peat monoliths from three microhabitats in the Mer Bleue peatland complex. Modern studies have shown that water table depth and vegetation have strong influences on the peatland methane cycle on instrumental time scales. With this new approach, delta C-13 of Sphagnum compounds are now a useful tool for investigating the relationships among hydrology, vegetation, and methanotrophy in Sphagnum peatlands over the time scales of entire peatland sediment records, vital to our understanding of the global carbon cycle through the Late Glacial and Holocene.

  10. Novel proxies for reconstructing paleohydrology from ombrotrophic peatlands: biomarker and compound-specific H and C stable isotope ratios

    Science.gov (United States)

    Wang, J.; Nichols, J. E.; Huang, Y.

    2008-12-01

    Ombrotrophic peatlands are excellent archives for paleohydrologic information because they are hydrologically isolated from their surroundings. However, quantitative proxies for deciphering peatland archives are lacking. Here, we present development and application of novel organic geochemical methods for quantitative reconstruction of paleohydrology from the ombrotrophic sediments, and comparison of organic geochemical data with conventional paleoecological proxies. Application of these methods to the sediments of several North American and European peatlands has revealed significant changes in the hydroclimate throughout the Holocene. The plant assemblage living at the surface of the peatland is tightly controlled by surface moisture. Under wet conditions, Sphagnum mosses, with no active mechanism for drawing water from below the surface of the peatland, are dominant. During dry conditions, vascular plants are more productive relative to Sphagnum. A ratio of the abundance of two biomarkers representing Sphagnum and vascular plants sensitively records changes in hydrologic balance (Nichols et al., 2006, Org. Geochem. 37, 1505-1513). We have further developed stable isotope models to compute climate parameters from compound-specific H and C isotope ratios of biomarkers to create a more comprehensive climate reconstruction. Vascular plant leaf waxes carry the D/H ratio signature of precipitation that is little affected by evaporation, whereas the Sphagnum biomarker records isotopic ratios of the water at the peatland surface, which is strongly enriched by evaporation. Evaporation amount can be calculated using the differences between D/H ratios of the two types of biomarkers. C isotope ratios of Sphagnum biomarkers can also be used to quantify surface wetness. Methanotrophic bacteria live symbiotically with Sphagnum, providing isotopically light carbon for photosynthesis. These bacteria are more active when the Sphagnum is wet, thus providing more 13C-depleted CO2

  11. Combined electrolysis catalytic exchange (CECE) process for hydrogen isotope separation

    International Nuclear Information System (INIS)

    Hammerli, M.; Stevens, W.H.; Butler, J.P.

    1978-01-01

    Hydrogen isotopes can be separated efficiently by a process which combines an electrolysis cell with a trickle bed column packed with a hydrophobic platinum catalyst. The column effects isotopic exchange between countercurrent streams of electrolytic hydrogen and liquid water while the electrolysis cell contributes to isotope separation by virtue of the kinetic isotope effect inherent in the hydrogen evolution reaction. The main features of the CECE process for heavy water production are presented as well as a discussion of the inherent positive synergistic effects, and other advantages and disadvantages of the process. Several potential applications of the process in the nuclear power industry are discussed. 3 figures, 2 tables

  12. Rare earth element and neodymium isotope tracing of element input and past ocean circulation. Study from north and south pacific seawater and sediments

    Energy Technology Data Exchange (ETDEWEB)

    Froellje, Henning

    2016-08-09

    incorporation of NADW contribute to the changes in the Nd isotope signature of CDW. The absence of such early deglacial Nd isotope changes in the northernmost core were attributed to the isolation of this core from bottom waters by South Pacific bathymetry with potential contribution from shifts in the Southern Ocean's frontal system and potential influence of increased deglacial NPDW convection. Overall the results highlight the important role of glacial deep stratification in sustaining a deep glacial carbon reservoir in the Southern Ocean and the importance of Southern Hemisphere climate to the breakdown of deep stratification and the release of sequestered CO{sub 2} through upwelling. A 140,000 year long Nd isotope record from the Southeast Pacific covering the last glacial-interglacial cycle demonstrates comparable deep water mass mixing in the South Pacific during the last two glacial maxima, but higher NADW contributions during the glacial Marine Isotope Stage (MIS) 4 (chapter 4). Likewise, the penultimate interglacial (MIS 5) was characterised by similar amounts of NADW and NPDW in CDW as the Holocene and the modern Southeast Pacific. Comparison of the last two glacial terminations thus shows high consistency and suggests similar mechanisms that controlled the deglacial change in water mass structure in the deep South Pacific, including a Southern Ocean contribution to early deglacial Nd isotope shifts. The results show weaker absolute glacial-interglacial Nd isotope changes compared to the South Atlantic due to the lack of direct NADW and slightly higher NPDW influence in the Southeast Pacific. Further, the Nd isotope record confirms the glacial-interglacial variability in NADW and NPDW mixture in CDW obtained previously from carbon isotope records.

  13. Rare earth element and neodymium isotope tracing of element input and past ocean circulation. Study from north and south pacific seawater and sediments

    International Nuclear Information System (INIS)

    Froellje, Henning

    2016-01-01

    incorporation of NADW contribute to the changes in the Nd isotope signature of CDW. The absence of such early deglacial Nd isotope changes in the northernmost core were attributed to the isolation of this core from bottom waters by South Pacific bathymetry with potential contribution from shifts in the Southern Ocean's frontal system and potential influence of increased deglacial NPDW convection. Overall the results highlight the important role of glacial deep stratification in sustaining a deep glacial carbon reservoir in the Southern Ocean and the importance of Southern Hemisphere climate to the breakdown of deep stratification and the release of sequestered CO_2 through upwelling. A 140,000 year long Nd isotope record from the Southeast Pacific covering the last glacial-interglacial cycle demonstrates comparable deep water mass mixing in the South Pacific during the last two glacial maxima, but higher NADW contributions during the glacial Marine Isotope Stage (MIS) 4 (chapter 4). Likewise, the penultimate interglacial (MIS 5) was characterised by similar amounts of NADW and NPDW in CDW as the Holocene and the modern Southeast Pacific. Comparison of the last two glacial terminations thus shows high consistency and suggests similar mechanisms that controlled the deglacial change in water mass structure in the deep South Pacific, including a Southern Ocean contribution to early deglacial Nd isotope shifts. The results show weaker absolute glacial-interglacial Nd isotope changes compared to the South Atlantic due to the lack of direct NADW and slightly higher NPDW influence in the Southeast Pacific. Further, the Nd isotope record confirms the glacial-interglacial variability in NADW and NPDW mixture in CDW obtained previously from carbon isotope records.

  14. Process for isotope separation

    International Nuclear Information System (INIS)

    Emile, B.F.M.

    1983-11-01

    A process is claimed for isotopic separation applied to isotopes of elements that can be placed in at least a physicochemical form in which the isotopic atoms or the molecules containing these atoms can be easily displaced and for which there are selective radiations preferentially absorbed by the isotopes of a certain type or by the molecules containing them, said absorption substantially increasing the probability of ionization of said atoms or molecules relative to the atoms or molecules that did not absorb the radiation. The process consists of placing the isotopic mixture in such a form, subjecting it in a separation zone to selective radiations and to an electrical field that produces migration of positive ions toward the negative electrodes and negative ions toward the positive electrodes, and withdrawing from certain such zones the fractions thus enriched in certain isotopes

  15. What controls the stable isotope composition of precipitation in the Mekong Delta? A model-based statistical approach

    Directory of Open Access Journals (Sweden)

    N. Le Duy

    2018-02-01

    Full Text Available This study analyzes the influence of local and regional climatic factors on the stable isotopic composition of rainfall in the Vietnamese Mekong Delta (VMD as part of the Asian monsoon region. It is based on 1.5 years of weekly rainfall samples. In the first step, the isotopic composition of the samples is analyzed by local meteoric water lines (LMWLs and single-factor linear correlations. Additionally, the contribution of several regional and local factors is quantified by multiple linear regression (MLR of all possible factor combinations and by relative importance analysis. This approach is novel for the interpretation of isotopic records and enables an objective quantification of the explained variance in isotopic records for individual factors. In this study, the local factors are extracted from local climate records, while the regional factors are derived from atmospheric backward trajectories of water particles. The regional factors, i.e., precipitation, temperature, relative humidity and the length of backward trajectories, are combined with equivalent local climatic parameters to explain the response variables δ18O, δ2H, and d-excess of precipitation at the station of measurement. The results indicate that (i MLR can better explain the isotopic variation in precipitation (R2  =  0.8 compared to single-factor linear regression (R2  =  0.3; (ii the isotopic variation in precipitation is controlled dominantly by regional moisture regimes (∼ 70 % compared to local climatic conditions (∼ 30 %; (iii the most important climatic parameter during the rainy season is the precipitation amount along the trajectories of air mass movement; (iv the influence of local precipitation amount and temperature is not significant during the rainy season, unlike the regional precipitation amount effect; (v secondary fractionation processes (e.g., sub-cloud evaporation can be identified through the d-excess and take

  16. What controls the stable isotope composition of precipitation in the Mekong Delta? A model-based statistical approach

    Science.gov (United States)

    Le Duy, Nguyen; Heidbüchel, Ingo; Meyer, Hanno; Merz, Bruno; Apel, Heiko

    2018-02-01

    This study analyzes the influence of local and regional climatic factors on the stable isotopic composition of rainfall in the Vietnamese Mekong Delta (VMD) as part of the Asian monsoon region. It is based on 1.5 years of weekly rainfall samples. In the first step, the isotopic composition of the samples is analyzed by local meteoric water lines (LMWLs) and single-factor linear correlations. Additionally, the contribution of several regional and local factors is quantified by multiple linear regression (MLR) of all possible factor combinations and by relative importance analysis. This approach is novel for the interpretation of isotopic records and enables an objective quantification of the explained variance in isotopic records for individual factors. In this study, the local factors are extracted from local climate records, while the regional factors are derived from atmospheric backward trajectories of water particles. The regional factors, i.e., precipitation, temperature, relative humidity and the length of backward trajectories, are combined with equivalent local climatic parameters to explain the response variables δ18O, δ2H, and d-excess of precipitation at the station of measurement. The results indicate that (i) MLR can better explain the isotopic variation in precipitation (R2 = 0.8) compared to single-factor linear regression (R2 = 0.3); (ii) the isotopic variation in precipitation is controlled dominantly by regional moisture regimes (˜ 70 %) compared to local climatic conditions (˜ 30 %); (iii) the most important climatic parameter during the rainy season is the precipitation amount along the trajectories of air mass movement; (iv) the influence of local precipitation amount and temperature is not significant during the rainy season, unlike the regional precipitation amount effect; (v) secondary fractionation processes (e.g., sub-cloud evaporation) can be identified through the d-excess and take place mainly in the dry season, either locally

  17. 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

  18. Isotopic marking and tracers

    International Nuclear Information System (INIS)

    Morel, F.

    1997-01-01

    The use of radioactive isotopes as tracers in biology has been developed thanks to the economic generation of the required isotopes in accelerators and nuclear reactors, and to the multiple applications of tracers in the life domain; the most usual isotopes employed in biology are carbon, hydrogen, phosphorus and sulfur isotopes, because these elements are present in most of organic molecules. Most of the life science knowledge appears to be dependent to the extensive use of nuclear tools and radioactive tracers; the example of the utilization of radioactive phosphorus marked ATP to study the multiple reactions with proteins, nucleic acids, etc., is given

  19. Isotopes in oxidation reactions

    International Nuclear Information System (INIS)

    Stewart, R.

    1976-01-01

    The use of isotopes in the study of organic oxidation mechanisms is discussed. The help provided by tracer studies to demonstrate the two-equivalent path - hydride transfer, is illustrated by the examples of carbonium oxidants and the Wacker reaction. The role of kinetic isotope effects in the study of the scission of carbon-hydrogen bonds is illustrated by hydride abstraction, hydrogen atom abstraction, proton abstraction and quantum mechanical tunnelling. Isotopic studies on the oxidation of alcohols, carbonyl compounds, amines and hydrocarbons are discussed. The role of isotopes in the study of biochemical oxidation is illustrated with a discussion on nicotinamide and flavin coenzymes. (B.R.H.)

  20. Isotope separation process

    International Nuclear Information System (INIS)

    Lyon, R.K.

    1976-01-01

    The instant invention relates to a process for separating a material into two or more parts in each of which the abundances of the isotopes of a given element differ from the abundances of the isotopes of the same material in said material. In one embodiment, the invention relates to a method for the isotopically selective excitation of gas phase molecules by multiple infrared photon absorption followed by selective dissociation of said excited molecules by the absorption of a single photon of visible or ultraviolet light. This invention is useful for, but not limited to, the separation of the principal isotopes of uranium. 11 Claims, 2 Drawing Figures

  1. 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

  2. Compositional and isotopic heterogeneities in the Neo-Tethyan upper mantle recorded by coexisting Al-rich and Cr-rich chromitites in the Purang peridotite massif, SW Tibet (China)

    Science.gov (United States)

    Xiong, Fahui; Yang, Jingsui; Xu, Xiangzhen; Kapsiotis, Argyrios; Hao, Xiaolin; Liu, Zhao

    2018-06-01

    The Purang harzburgite massif in SW Tibet (China) hosts abundant chrome ore deposits. Ores consist of 20 to >95% modal chromian spinel (Cr-spinel) with mylonitic fabric in imbricate shaped pods. The composition of Cr-spinel in these ores ranges from Al-rich [Cr#Sp or Cr/(Cr + Al) × 100 = 47.60-57.56] to Cr-rich (Cr#Sp: 62.55-79.57). Bulk platinum-group element (PGE) contents of chromitites are also highly variable ranging from 17.5 ppb to ∼2.5 ppm. Both metallurgical and refractory chromitites show a general enrichment in the IPGE (Os, Ir and Ru) with respect to the PPGE (Rh, Pt and Pd), resulting mostly in right-sloping primitive mantle (PM)-normalized PGE profiles. The platinum-group mineral (PGM) assemblages of both chromitite types are dominated by heterogeneously distributed, euhedral Os-bearing laurite inclusions in Cr-spinel. The Purang chromitites have quite inhomogeneous 187Os/188Os ratios (0.12289-0.13194) that are within the range of those reported for mantle-hosted chromitites from other peridotite massifs. Geochemical calculations demonstrate that the parental melts of high-Cr chromitites were boninitic, whereas those of high-Al chromitites had an arc-type tholeiitic affinity. Chromite crystallization was most likely stimulated by changes in magma compositions due to melt-peridotite interaction, leading to the establishment of a heterogeneous physicochemical environment during the early crystallization of the PGM. The highly variable PGE contents, inhomogeneous Os-isotopic compositions and varying Cr#Sp ratios of these chromitites imply a polygenetic origin for them from spatially distinct melt inputs. The generally low γOs values (different sections of a heterogeneously depleted mantle source region. These melts were most likely produced in the mantle wedge above a downgoing lithospheric slab.

  3. Isotope hydrology: applied discipline in earth sciences

    International Nuclear Information System (INIS)

    Froehlich, K.; Rozanski, K.; Araguas Araguas, L.

    1998-01-01

    The discipline 'isotope hydrology' is being reviewed from the perspective of the Isotope Hydrology Section of the International Atomic Energy Agency in Vienna. The Section was created in the late fifties and is activities involved int the scientific progress of the discipline. The role of the IAEA in the development of isotope hydrology has always been of a dual nature: on one hand, the Section has been and still is heavily engaged in supporting and coordinating further development of isotope methodologies, on the other hand, it serves as an interface between the methodological development in research institutes and the applied work using proven techniques in field projects on water resources assessment and management. The paper provides a brief overview of applications of isotope-based methodologies in hydrology, with emphasis on new trends and challenges related to man's growing impact on the water cycle. This contribution is a tribute to the memory of the former Head of the Isotope Hydrology Section, Jean-Charles Fontes, to whom we owe so much. (authors)

  4. Isotopic diagnosis of peripheral thrombosis

    International Nuclear Information System (INIS)

    Cornu, Pierre; Scalet, Michel

    1975-01-01

    Radio-isotope diagnosis of peripheral venous thrombosis, using tracer doses of iodine-labelled fibrinogen, provides an important contribution to the solution of the worrying problem of pulmonary embolism due to latent phlebitis. This elegant and precise technique permits early diagnosis of venous thrombosis of the lower limbs at a subclinical stage. It has permitted determination of the frequency, both after surgery and after myocardial infarction, and above all, it provides an objective criterion for assessment of the efficacy of prophylactic measures proposed [fr

  5. 18O, 2H and 3H isotopic composition of precipitation and shallow groundwater in Olkiluoto

    International Nuclear Information System (INIS)

    Hendriksson, N.; Karhu, J.; Niinikoski, P.

    2014-12-01

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

  6. Intracellular Cadmium Isotope Fractionation

    Science.gov (United States)

    Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

    2011-12-01

    Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

  7. Discovery of the iron isotopes

    International Nuclear Information System (INIS)

    Schuh, A.; Fritsch, A.; Heim, M.; Shore, A.; Thoennessen, M.

    2010-01-01

    Twenty-eight iron isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  8. Discovery of the silver isotopes

    International Nuclear Information System (INIS)

    Schuh, A.; Fritsch, A.; Ginepro, J.Q.; Heim, M.; Shore, A.; Thoennessen, M.

    2010-01-01

    Thirty-eight silver isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  9. Discovery of the cadmium isotopes

    International Nuclear Information System (INIS)

    Amos, S.; Thoennessen, M.

    2010-01-01

    Thirty-seven cadmium isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  10. 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

    implications of advances in understanding in these areas for the interpretation of palaeo records and proxy data – climate model comparison.Here, we briefly review these areas of research, and discuss challenges for the water isotope community in improving our ability to partition climate vs. auxiliary signals in palaeoclimate data.

  11. Isotope scanning for tumor localization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1961-09-15

    At the request of the Government of the United Arab Republic, the Agency provided the services of an expert for the establishment in the UAR of a tumor localization program using photoscanning techniques and appropriate radioactive tracers. Photoscanning is a recently developed technique whereby the differences in isotope concentrations are enhanced on the record, and this facilitates the interpretation of the record. A variety of brain tumors were located, using a suitable radioactive tracer (Hg-203 - labelled Neohydrin) obtained from the USA. In some other investigations, processes in the kidney were scanned. Further, radioactive gold was used to demonstrate the normal and pathological spleen and liver and these tests showed various types of space occupying lesions resulting from malignancy and the parasitic infections endemic to the area. While the localization of brain tumors by scanning techniques is extremely useful, it does not always establish the precise extent of the tumor which should be known at the time of surgery. Dr. Bender, therefore, thought it advisable to instruct personnel in the use of what is known as an in-vivo needle scintillation probe - a technique for the investigation of the isotope concentration in a particular tissue during operation. The necessary instrument was obtained for this purpose and demonstrations were given; one patient was examined in this way at the time of surgery at the University of Alexandria Hospital.

  12. Isotopic research in Antarctica

    International Nuclear Information System (INIS)

    Schuetze, H.

    1983-01-01

    Since 1978 scientists of the Central Institute of Isotope- and Radiation Research of the Academy of Sciences of the GDR have participated in antarctic research. Substantial results have been achieved in research on isotope ratios, on the dynamics of water resources, on concentration of deuterium in lichens, and on age determination of a mummified seal and a penguin colony

  13. Uses of stable isotopes

    International Nuclear Information System (INIS)

    Axente, Damian

    1998-01-01

    The most important fields of stable isotope use with examples are presented. These are: 1. Isotope dilution analysis: trace analysis, measurements of volumes and masses; 2. Stable isotopes as tracers: transport phenomena, environmental studies, agricultural research, authentication of products and objects, archaeometry, studies of reaction mechanisms, structure and function determination of complex biological entities, studies of metabolism, breath test for diagnostic; 3. Isotope equilibrium effects: measurement of equilibrium effects, investigation of equilibrium conditions, mechanism of drug action, study of natural processes, water cycle, temperature measurements; 4. Stable isotope for advanced nuclear reactors: uranium nitride with 15 N as nuclear fuel, 157 Gd for reactor control. In spite of some difficulties of stable isotope use, particularly related to the analytical techniques, which are slow and expensive, the number of papers reporting on this subject is steadily growing as well as the number of scientific meetings organized by International Isotope Section and IAEA, Gordon Conferences, and regional meeting in Germany, France, etc. Stable isotope application development on large scale is determined by improving their production technologies as well as those of labeled compound and the analytical techniques. (author)

  14. Detecting isotopic ratio outliers

    International Nuclear Information System (INIS)

    Bayne, C.K.; Smith, D.H.

    1985-01-01

    An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers. 6 refs., 3 figs., 3 tabs

  15. Stable isotopes labelled compounds

    International Nuclear Information System (INIS)

    1982-09-01

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  16. 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.

  17. Separation of uranium isotopes

    International Nuclear Information System (INIS)

    Porter, J.T.

    1980-01-01

    Methods and apparatus are disclosed for separation of uranium isotopes by selective isotopic excitation of photochemically reactive uranyl salt source material at cryogenic temperatures, followed by chemical separation of selectively photochemically reduced U+4 thereby produced from remaining uranyl source material

  18. Isotope research materials

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    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 241 Am metallurgical specimen; reactor dosimeters; ceramic and cermet development; fission-fragment-generating targets of 235 UO 2 ; and wire dosimeters for Westinghouse--Bettis

  19. Isotope separation process

    International Nuclear Information System (INIS)

    Lyon, R.K.

    1979-01-01

    A method is described for the isotopically selective excitation of gas phase molecules by multiple infrared photon absorption after which more of the excited molecules than nonexcited molecules are converted to a chemically different form which may be separated by means known in the art. This invention is useful for, but not limited to, the separation of the principal isotopes of uranium

  20. Superdeformation in Pb isotopes

    International Nuclear Information System (INIS)

    Naz, Tabassum; Ahmad, Shakeb

    2017-01-01

    The Relatvistic Hartree-Bogoliubov (RHB) theory is used to explore the structure of superdeformed (SD) 190,212 Pb isotopes using the non-linear NL3* and density dependent (DD-ME2, DD-PC1) interactions. We have studied the the excitation energy, the potential depth and the deformation of these Pb isotopes

  1. Detecting isotopic ratio outliers

    Science.gov (United States)

    Bayne, C. K.; Smith, D. H.

    An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers.

  2. Detecting isotopic ratio outliers

    International Nuclear Information System (INIS)

    Bayne, C.K.; Smith, D.H.

    1986-01-01

    An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers

  3. Isotope dilution analysis

    Energy Technology Data Exchange (ETDEWEB)

    Fudge, A.

    1978-12-15

    The following aspects of isotope dilution analysis are covered in this report: fundamental aspects of the technique; elements of interest in the nuclear field, choice and standardization of spike nuclide; pre-treatment to achieve isotopic exchange and chemical separation; sensitivity; selectivity; and accuracy.

  4. Wide angle isotope separator

    International Nuclear Information System (INIS)

    Kantrowitz, A.

    1976-01-01

    A method and apparatus is described for particle separation. The method uses a wide angle radially expanding vapor of a particle mixture. In particular, selective ionization of one isotope type in the particle mixture is produced in a multichamber separator and the ionized isotope type is accelerated out of the path of the vapor expansion for separate collection

  5. Environmental isotope hydrology

    International Nuclear Information System (INIS)

    1973-01-01

    Environmental isotope hydrology is a relatively new field of investigation based on isotopic variations observed in natural waters. These isotopic characteristics have been established over a broad space and time scale. They cannot be controlled by man, but can be observed and interpreted to gain valuable regional information on the origin, turnover and transit time of water in the system which often cannot be obtained by other techniques. The cost of such investigations is usually relatively small in comparison with the cost of classical hydrological studies. The main environmental isotopes of hydrological interest are the stable isotopes deuterium (hydrogen-2), carbon-13, oxygen-18, and the radioactive isotopes tritium (hydrogen-3) and carbon-14. Isotopes of hydrogen and oxygen are ideal geochemical tracers of water because their concentrations are usually not subject to change by interaction with the aquifer material. On the other hand, carbon compounds in groundwater may interact with the aquifer material, complicating the interpretation of carbon-14 data. A few other environmental isotopes such as 32 Si and 238 U/ 234 U have been proposed recently for hydrological purposes but their use has been quite limited until now and they will not be discussed here. (author)

  6. Contribution to the study of isotopic exchange of oxygen between nickel oxide and the gases arising from the oxidation reaction of carbon monoxide; Contribution a l'etude de l'echange isotopique de l'oxygene entre l'oxyde de nickel et les gaz de la reaction d'oxydation de l'oxyde de carbone

    Energy Technology Data Exchange (ETDEWEB)

    Bailly, J C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-12-01

    The 3 isotopic reactions of oxygen: C{sup 18}O + Ni{sup 16}O {r_reversible} C{sup 16}O + Ni{sup 18}O, {sup 16}O{sup 18}O + Ni{sup 16}O {r_reversible} {sup 16}O{sub 2} + Ni{sup 18}O, and C{sup 16}O{sup 18}O + Ni{sup 16}O {r_reversible} C{sup 16}O{sub 2} + Ni{sup 18}O between CO, CO{sub 2}, O{sub 2} and NiO are studied using a mass spectrometer. The isotopic gaseous mixtures are prepared from oxygen-18 enriched water. A first order kinetic law has been found for these reactions in the gaseous phase, and the activation energies have been determined. Only CO and CO{sub 2} exchange oxygen, at room temperature, but only with part of the oxide surface. Gaseous O{sub 2} reacts with the whole surface at 250 C, the slow step of the exchange process, in the gaseous phase, being certainly the mobility of oxygen ions on the surface of NiO. (author) [French] Les 3 reactions d'echange isotopique de l'oxygene: C{sup 18}O + Ni{sup 16}O {r_reversible} C{sup 16}O + Ni{sup 18}O, {sup 16}O{sup 18}O + Ni{sup 16}O {r_reversible} {sup 16}O{sub 2} + Ni{sup 18}O, et C{sup 16}O{sup 18}O + Ni{sup 16}O {r_reversible} C{sup 16}O{sub 2} + Ni{sup 18}O entre l'oxyde de carbone, l'oxygene gazeux, le gaz carbonique et l'oxyde de nickel sont etudiees par spectrometrie de masse. Les melanges isotopiques gazeux sont prepares a partir d'une eau enrichie en isotope 18 de l'oxygene. Une loi cinetique du premier ordre a ete trouvee pour les trois reactions d'echange en phase gazeuse, et des energies d'activation de ces reactions ont ete determinees. Seuls CO et CO{sub 2} echangent l'oxygene, des la temperature ambiante, mais avec une fraction seulement de la surface de l'oxyde. O{sub 2} gazeux reagit avec toute la surface du solide a 250 C, l'etape lente du processus d'echange en phase gazeuse etant vraisemblablement liee a la mobilite des ions oxygene superficiels de NiO. (auteur)

  7. Laser assisted aerodynamic isotope separation

    International Nuclear Information System (INIS)

    Berg, H. van den

    1985-01-01

    It is shown that the efficiency of conventional aerodynamic isotope seperation can be improved by two orders of magnitude with the aid of a relatively weak cw infrared laser which is used to induce isotopically selective condensation. Overall isotope enrichment factors in excess of 2 are obtained as compared to about 1.02 in the conventional seperation. Sulphur isotopes in SF 6 as well as Silicon isotopes in SiF 4 and Bromine isotopes in CF 3 Br are seperated on a laboratory scale. Infrared vibrational predissociation by itself and in combination with isotopically selective condensation are also shown to be effective new ways of isotope separation. (orig.) [de

  8. Isotopes in Greenland Precipitation

    DEFF Research Database (Denmark)

    Faber, Anne-Katrine

    Greenland ice cores offer a unique opportunity to investigate the climate system behaviour. The objective of this PhD project is to investigate isotope modelling of present- day conditions and conduct model-data comparison using Greenland ice cores. Thus this thesis investigates how the integration...... of model and data can be used to improve the understanding of climate changes. This is done through analysis of isotope modelling, observations and ice core measurements. This dissertation comprises three projects: (1) Modelling the isotopic response to changes in Arctic sea surface conditions, (2......) 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...

  9. Applications of isotopes

    International Nuclear Information System (INIS)

    Kirby-Smith, J.S.

    1976-01-01

    Current and potential applications of stable isotopes as tracers in a number of biomedical and environmental areas are discussed. It is pointed out that a wide variety of problems exist in these fields whose solutions in principle are amenable to the isotopic approach. The number and diversity of these problems as well as the unique role stable isotopes can play in their solution illustrate the importance of achieving and maintaining a broad inventory of isotopic species. Experience has demonstrated unequivocally an additional overriding requirement for widespread exploration of stable isotopes by the scientific and technical community, i.e., the need for low cost availability of the materials in quantity. Some representative applications of 12 C, 13 C, 14 N, 15 N, 16 O, 17 O, and 18 O are discussed

  10. Contribution to the study of a method for measuring continuously the isotopic effect. The search for an isotopic effect during the reduction of cuprous oxide by a {sup 12}CO - {sup 14}CO mixture (1962); Contribution a l'etude d'une methode de mesure continue de l'effet isotopique. Recherche d'un effet isotopique dans la reduction de l'oxyde cuivreux par le melange {sup 12}CO - {sup 14}CO (1962)

    Energy Technology Data Exchange (ETDEWEB)

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

    1961-07-15

    The determination of an isotopic effect between the two reactions: {sup 12}CO + Cu{sub 2}O {yields} {sup 12}CO{sub 2} + 2 Cu 'light' reaction {sup 14}CO + Cu{sub 2}O {yields} {sup 14}C{sub O}2 + 2 Cu 'heavy' reaction is possible if the respective kinetics are known. The condensation, during the reaction, of the carbon dioxide formed, and the measurement as a function of time of the residual carbon monoxide pressure, makes it possible to deduce, uninterruptedly, the 'light' reaction kinetics. The 'heavy' reaction kinetics are obtained by measuring continuously, in situ, the radioactivity of the residual reactant gas as a function of the time. The apparatus used for this is a plastic scintillator counter. A calibration curve of the measured radioactivity as a function of the reactant gas pressure in the absence of reaction makes it possible to compare the kinetics of the 'light' and 'heavy' reactions. The reaction temperature is chosen such that the reaction rate is sufficiently slow, so that the variation of the radioactivity during unit counting time is negligible. (author) [French] La determination d'un effet isotopique entre les deux reactions: {sup 12}CO + Cu{sub 2}O {yields} {sup 12}CO{sub 2} + 2 Cu reaction 'legere' {sup 14}CO + Cu{sub 2}O {yields} {sup 14}C{sub O}2 + 2 Cu reaction 'lourde' est rendue possible par la connaissance de leurs cinetiques respectives. La condensation, au cours de la reaction, du gaz carbonique forme et la mesure en fonction du temps de la pression de l'oxyde de carbone residuel, permet d'obtenir, de facon continue, la cinetique de la reaction 'legere'. La cinetique de la reaction lourde est determinee par la mesure continue, in situ, du taux de radioactivite du reactif gazeux residuel en fonction du temps. Le dispositif employe dans ce but est un compteur a scintillateur plastique. Une courbe d'etalonnage, du taux mesure de radioactivite en fonction de la pression du gaz reactif, en l'absence de reaction, permet de comparer les

  11. Prospects and Challenges in tropical isotope dendroclimatology

    Science.gov (United States)

    Evans, M. N.; Anchukaitis, K. J.; White, S. R.; Ektvedt, T. M.; Penniston, R. C.; Rheaume, M. M.; Bowman, D. M.

    2008-12-01

    We review a stable isotope-based approach to the development, modeling, interpretation, and analysis of hydrometeorological estimates from tropical trees. The strategy overcomes the common problem of missing, intermittent or non-annual ring structure in tropical trees by relying instead on the observation of the annual wet-dry seasonality typical to tropical environments as mirrored in the oxygen isotopic composition of wood-derived α-cellulose. We explore regions for which forward modeling of the proxy system would expect us to resolve hydrometeorological variations associated with the El Niño-Southern Oscillation (ENSO) phenomenon, rather than being limited to regions with tree species or environments producing verifiable annual ring chronologies. A modified protocol allows for rapid, simple and non-toxic micro-extraction of pure α-cellulose, which is isotopically indistinguishable from that produced by more classical means. We describe a new reactor for the pyrolysis of α-cellulose in an induction heater, which permits isotopic analysis of α-cellulose samples as small as 30μg, and as many as 100 automated sample analyses per day. A forward model adapted for tropical environments can be used to test and refine the interpretation of the isotopic data, and to predict locales for which we should be able to maximize the paleoclimatic potential of future sample collections. We have found the modeled isotopic chronometer and raingage in agreement with independent chronological controls in a variety of environments and tree species in Costa Rica, Indonesia, Brazil, Peru and Australia. Development of long hydrometeorological records from the terrestrial tropics is underway not only by our group, but by a growing number of collaborators and colleagues. Together we should be able to build a network of paleoprecipitation records and better understand the linkages between tropical surface ocean temperatures and large-scale drought.

  12. Oxygen isotope mass balance of atmospheric nitrate at Dome C, East Antarctica, during the OPALE campaign

    Directory of Open Access Journals (Sweden)

    J. Savarino

    2016-03-01

    Full Text Available Variations in the stable oxygen isotope composition of atmospheric nitrate act as novel tools for studying oxidative processes taking place in the troposphere. They provide both qualitative and quantitative constraints on the pathways determining the fate of atmospheric nitrogen oxides (NO + NO2 = NOx. The unique and distinctive 17O excess (Δ17O = δ17O − 0.52 × δ18O of ozone, which is transferred to NOx via oxidation, is a particularly useful isotopic fingerprint in studies of NOx transformations. Constraining the propagation of 17O excess within the NOx cycle is critical in polar areas, where there exists the possibility of extending atmospheric investigations to the glacial–interglacial timescale using deep ice core records of nitrate. Here we present measurements of the comprehensive isotopic composition of atmospheric nitrate collected at Dome C (East Antarctic Plateau during the austral summer of 2011/2012. Nitrate isotope analysis has been here combined for the first time with key precursors involved in nitrate production (NOx, O3, OH, HO2, RO2, etc. and direct observations of the transferrable Δ17O of surface ozone, which was measured at Dome C throughout 2012 using our recently developed analytical approach. Assuming that nitrate is mainly produced in Antarctica in summer through the OH + NO2 pathway and using concurrent measurements of OH and NO2, we calculated a Δ17O signature for nitrate on the order of (21–22 ± 3 ‰. These values are lower than the measured values that ranged between 27 and 31 ‰. This discrepancy between expected and observed Δ17O(NO3− values suggests the existence of an unknown process that contributes significantly to the atmospheric nitrate budget over this East Antarctic region. However, systematic errors or false isotopic balance transfer functions are not totally excluded.

  13. Barium isotopes in cold-water corals

    Science.gov (United States)

    Hemsing, Freya; Hsieh, Yu-Te; Bridgestock, Luke; Spooner, Peter T.; Robinson, Laura F.; Frank, Norbert; Henderson, Gideon M.

    2018-06-01

    Recent studies have introduced stable Ba isotopes (δ 138 / 134Ba) as a novel tracer for ocean processes. Ba isotopes could potentially provide insight into the oceanic Ba cycle, the ocean's biological pump, water-mass provenance in the deep ocean, changes in activity of hydrothermal vents, and land-sea interactions including tracing riverine inputs. Here, we show that aragonite skeletons of various colonial and solitary cold-water coral (CWC) taxa record the seawater (SW) Ba isotope composition. Thirty-six corals of eight different taxa from three oceanic regions were analysed and compared to δ 138 / 134Ba measurements of co-located seawater samples. Sites were chosen to cover a wide range of temperature, salinity, Ba concentrations and Ba isotope compositions. Seawater samples at the three sites exhibit the well-established anti-correlation between Ba concentration and δ 138 / 134Ba. Furthermore, our data set suggests that Ba/Ca values in CWCs are linearly correlated with dissolved [Ba] in ambient seawater, with an average partition coefficient of DCWC/SW = 1.8 ± 0.4 (2SD). The mean isotope fractionation of Ba between seawater and CWCs Δ138/134BaCWC-SW is -0.21 ± 0.08‰ (2SD), indicating that CWC aragonite preferentially incorporates the lighter isotopes. This fractionation likely does not depend on temperature or other environmental variables, suggesting that aragonite CWCs could be used to trace the Ba isotope composition in ambient seawater. Coupled [Ba] and δ 138 / 134Ba analysis on fossil CWCs has the potential to provide new information about past changes in the local and global relationship between [Ba] and δ 138 / 134Ba and hence about the operation of the past global oceanic Ba cycle in different climate regimes.

  14. Sulfur isotopic analysis of carbonyl sulfide and its application for biogeochemical cycles

    Science.gov (United States)

    Hattori, Shohei; Kamezaki, Kazuki; Ogawa, Takahiro; Toyoda, Sakae; Katayama, Yoko; Yoshida, Naohiro

    2016-04-01

    reaction does not contribute to the MIF signatures observed in sulfate aerosol samples and/or Archaean rock records. At the presentation, we report the comparison of 34ɛ values determined using some strains and the atmospheric implications for the OCS degradation in the present atmosphere are discussed. Hattori, S., Danielache, S. O., Johnson, M. S., Schmidt, J. A., Kjaergaard, H. G., Toyoda, S., Ueno, Y., Yoshida, N. Ultraviolet absorption cross sections of carbonyl sulfide isotopologues OC32S, OC33S, OC34S and O13CS: isotopic fractionation in photolysis and atmospheric implications, Atmos. Chem. Phys., 11, 10293-10303, 2011. Schmidt, J. A., Johnson, M. S., Jung, Y., Danielache, S. O., Hattori, S., Yoshida, N., Predictions of the sulfur and carbon kinetic isotope effects in the OH + OCS reaction, Chem. Phys. Lett., 531, 64-69, 2012. Hattori, S., Schmidt J. A., Mahler D., Danielache, S. O., Johnson M. S., Yoshida N. Isotope Effect in the Carbonyl Sulfide Reaction with O(3P), J. Phys. Chem. A, 116, 3521-3526, 2012. Hattori, S., Toyoda, A., Toyoda, S., Ishino S., Ueno, Y., Yoshida, N.: Determination of the Sulfur Isotope Ratio in Carbonyl Sulfide using Gas Chromatography/Isotope Ratio Mass Spectrometry on Fragment Ions 32S+, 33S+, and 34S+, Anal. Chem., 87, 477-484, 2015. Kato, H., Saito, M., Nagahata, Y., Katayama, Y.: Degradation of ambient carbonyl sulfide by Mycobacterium spp. in soil. Microbiol., 154(1), 249-255, 2008.

  15. 61 stable isotope compositions of organic carbon and contents of ...

    African Journals Online (AJOL)

    Mgina

    isotope record from Lake Ndutu shows a general downcore decrease in δ. 13C values ... in bulk δ13C of the terrestrial biomass in the tropics may ... CO2, temperature, moisture conditions and ... A map showing location of sampling sites of Ngorongoro Crater, Lake Ndutu and .... the Lakes Makat and Masek records cannot.

  16. GEOCHEMICAL AND ISOTOPIC INVESTIGATION OF LAKES IN THE TRENTO PROVINCE (ITALY

    Directory of Open Access Journals (Sweden)

    Marco Natale

    2013-09-01

    Full Text Available We present the geochemical composition and the stable isotope signature (18O/16O and 2H/1H of waters sampled from six lakes (Caldonazzo, Levico, Lases, Santa Colomba, Lamar and Santo located in the Province of Trento. The chemical compositions invariably revealed a HCO3-Ca hydrochemical facies; however slight differences were observed among the lakes, in relation to the lithologies distinguishing each lakes’drainage basin. Elemental ratios and in particular the Rb/Sr provide a discriminative tool to recognize the rocks that have been weathered; for example this ratio is high in water that interacted with volcanic ignimbrites (rhyolites, and low in rocks that interacted with carbonate rocks. Many other trace elements were analyzed, thus providing baseline data, and only arsenic displayed concentrations higher than the legislative threshold defined for drinking water (10mg/l, especially in Lake Levico (10-19 mg/l. As concerns the stable isotopes δD and δ18O, the obtained results approach the meteoric signature for waters sampled during the 2012 winter season. The waters sampled during two summers (2011 and 2012 displayed distinctive trends, reflecting the significant influence of evaporative processes. We emphasize that the annual differences recorded in the isotopic composition of distinct years are plausibly related to temperature changes and type of precipitation that recharged the lakes. In this light, the peculiar isotopic signature recorded in the year 2011 is possibly related to a significant snowy period, which greatly contributed to the lakes’ water budget. Interestingly, waters from Lake Santa Colomba were systematically different from all the other samples, possibly due to more effective evaporative processes, or to the involvement of deep underground recharge including fossil waters.

  17. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    the δ53Cr value of continental runoff into the ocean. The major findings were that river water is characterised by heavy δ53Cr values (+0.1‰ to +1.6‰), while soils are characterised by light δ53Cr values (-0.3‰), relative to the catchment bedrock (-0.17‰ to -0.21‰), indicating that Cr isotopes......, 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......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...

  18. Phenological Records

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Phenology is the scientific study of periodic biological phenomena, such as flowering, breeding, and migration, in relation to climatic conditions. The few records...

  19. Assessing wine quality using isotopic methods

    International Nuclear Information System (INIS)

    Costinel, Diana; Ionete, Roxana Elena; Vremera, Raluca; Stefanescu, Ioan

    2010-01-01

    Full text: The analytical methods used to determine the isotope ratios of deuterium, carbon-13 and oxygen-18 in wines have gained official recognition from the Office International de la Vigne et du Vin (OIV) and National Organisation of Vine and Wine. The amount of stable isotopes in water and carbon dioxide from plant organic materials and their distribution in sugar and ethanol molecules are influenced by geo-climatic conditions of the region, grape varieties and the year of harvest. For wine characterization, to prove the botanical and geographical origin of the raw material, the isotopic analysis by continuous flow mass spectrometry CF-IRMS has made a significant contribution. This paper emphasize the results of a study concerning the assessing of water adulterated wines and non-grape alcohol and sugar additions at different concentration levels, using CF-IRMS analytical technique. (authors)

  20. Isotope separation process

    International Nuclear Information System (INIS)

    1976-01-01

    The invention relates to a process for separating a given material into two or more parts, in each of which the abundances of the isotopes of a given element differ from the abundances of the isotopes of the same material in the said material. More particularly, the invention relates to a method for the isotopically selective excitation of gas phase UF 6 by infrared photon absorption followed by selective reaction of said excited UF 6 with atomic chlorine, bromine, or iodine to form a product which may be separated by means known in the art

  1. Radiation gradient isotope separator

    International Nuclear Information System (INIS)

    Hughes, J.L.

    1980-01-01

    A system is described for transporting, separating and storing charged particles, charged antiparticles and fully or partially ionized isotopes of any element comprising a laser beam generator, laser beam intensity profiler, a laser beam variable intensity attenuator, and means for injecting charged particles, charged antiparticles and ionized isotopes into the beam and extracting them from the system as required. The invention is particularly useful for channelling electrons and ions used for fuel pellet compression in inertial fusion systems, for separating the isotopes of elements and for the confinement of charged antiparticles and particle/antiparticle plasmas

  2. Atomic and molecular isotope separation

    International Nuclear Information System (INIS)

    Melamed, N.T.

    1979-01-01

    A method for differentially exciting a selected isotopic species in a mixture of isotopic species is described characterized in that almost the entire isotopic mixture is placed in an excited gaseous state; and a preselected isotopic species is then selectively de-excited through stimulated emission

  3. Radiometric report for a blast furnace tracing with radioactive isotopes

    International Nuclear Information System (INIS)

    Tanase, G.; Tanase, M.

    1995-01-01

    One of the methods to monitor refractory wall of blast furnace is its tracing with radioactive isotopes. The tracer isotope can be detected by two ways: the external dosimetric measurement at the armour of the blast furnace and/or the radiometric measurement of the iron sample charge by charge. Any change in radiometric situation of tracer radioisotope is recorded in a radiometric report. This paper presents an original concept of radiometric report based upon PARADOX and CORELDRAW soft kits. Their advantage are: quick and easy changes, easy recording of current radioactivity of tracer isotope, short history of changes, visual mapping of the tracer isotope and others. In this way we monitored 6 blast furnaces and more than 180 radioactive sources

  4. 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.

  5. Sec