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Sample records for content isotopic composition

  1. Stable isotope compositions of organic carbon and contents of ...

    African Journals Online (AJOL)

    The stable isotope compositions of organic carbon (OC), and contents of OC and nitrogen for four sediment cores recovered from lakes Makat (located in the Ngorongoro Crater), Ndutu and Masek (located in the Serengeti Plains) are used to document sources of organic matter (OM) and climatic changes in sub-arid ...

  2. Comparison of different methods of determining plutonium content and isotopic composition

    International Nuclear Information System (INIS)

    Dowell, M.R.W.

    1985-05-01

    At Rockwell Hanford Operations, several different methods are used to determine plutonium content and isotopic composition. These include alpha particle energy analysis, calorimetry/gamma-ray analysis, mass spectrometry, and low energy ray assay. Each is used in a process control environment and has its advantages and disadvantages in terms of sample matrix, sample preparation, concentration, error ranges, detection limits, and turn around time. Of the methods discussed, special attention is paid to the Plutonium Isotopics Solution Counter, a low energy gamma ray assay system designed to provide plutonium and americium content and isotopic composition of Pu-238 through Pu-241 and Am-241. It is qualitatively and quantitatively compared to the other methods. A brief description of sample types which the Solution Counter analyzes is presented. 4 refs., 4 tabs

  3. Comparison of different methods of determining plutonium content and isotopic composition

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    At Rockwell Hanford Operations, several different methods are used to determine plutonium content and isotopic composition. These include alpha particle energy analysis, calorimetry/gamma-ray analysis, mass spectrometry, and low energy gamma-ray assay. Each is used in a process control environment and has its advantages and disadvantages in terms of sample matrix, sample preparation, concentration, error ranges, detection limits, and turn around time. Of the methods discussed, special attention is paid to the Plutonium Isotopics Solution Counter, a low energy gamma-ray assay system designed to provide plutonium and americium content and isotopic composition of Pu-238 through Pu-241 and Am-241. It is qualitatively and quantitatively compared to the other methods. A brief description of sample types which the Solution Counter analyzes is presented

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

    Science.gov (United States)

    Komor, S.C.

    1997-01-01

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

  5. Boron contents and isotope compositions of oceanic crusts from the Oman and Troodos ophiolites

    Science.gov (United States)

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

    2011-12-01

    Boron is excellent tracer for elucidating crustal recycling in subduction zones because of the high concentration of boron in the upper part of the slab and the high mobility of boron during dehydration of the slab. However, fundamental data for vertical distribution of boron in hydrothermally altered oceanic crust are still limited. In this study, boron contents and isotopic compositions were determined for complete section of the oceanic crusts in the Oman and Troodos ophiolite. Although the boron contents of rocks decreased with depth in both the oceanic crusts, altered rocks from deep section showed obvious boron enrichment relative to fresh rocks. The pillow lavas in the Troodos ophiolite, which have been weathered on the seafloor for ~80 Myrs, was highly enriched in boron (>100 ppm), supporting that boron inventory of pillow lava section strongly depends on the crustal age. The δ11B of rocks in the Oman ophiolite systematically increased with depth and negatively correlate with the δ18O values, suggesting that the δ11B values are essentially controlled by alteration temperature. On the other hand, the δ11B profile in the Troodos ophiolite didn't show clear increase trend. The boron contents for the bulk oceanic crusts of the Oman and Troodos ophiolites are estimated to be 3.6 ppm and 12 ppm, respectively. About 8% of δ11B was estimated for both the bulk oceanic crusts. In contrast to previous views, hydrothermally altered gabbro section can be a large sink of boron. This boron-enriched, high-δ11B lower oceanic crust may impact on the estimate of the δ11B value for fluids librated from the subducted oceanic slab, which is believed to largely control the δ11B values of arc magmas generated in the mantle wedge.

  6. Using trace element content and lead isotopic composition to assess sources of PM in Tijuana, Mexico

    Science.gov (United States)

    Salcedo, D.; Castro, T.; Bernal, J. P.; Almanza-Veloz, V.; Zavala, M.; González-Castillo, E.; Saavedra, M. I.; Perez-Arvízu, O.; Díaz-Trujillo, G. C.; Molina, L. T.

    2016-05-01

    PM2.5 samples were collected at two urban sites (Parque Morelos (PQM) and CECyTE (CEC)) in Tijuana during the Cal-Mex campaign from May 24 to June 5, 2010. Concentration of trace elements (Mg, Al, Ti, V, Mn, Fe, Co, Ni, Zn, Cu, Ga, As, Se, Rb, Sr, Mo, Cd, Sn, Sb, Ba, La, Ce, and Pb), and Pb isotopic composition were determined in order to study the sources of PM impacting each site. Other chemical analysis (gravimetric, elemental and organic carbon (EC/OC), and polycyclic aromatic hydrocarbons (PAHs)), were also performed. Finally, back-trajectories were calculated to facilitate the interpretation of the chemical data. Trace elements results show that CEC is a receptor site affected by mixed regional sources: sea salt, mineral, urban, and industrial. On the other hand, PQM seems to be impacted mainly by local sources. In particular, Pb at CEC is of anthropogenic, as well as crustal origin. This conclusion is supported by the lead isotopic composition, whose values are consistent with a combination of lead extracted from US mines, and lead from bedrocks in the Mexican Sierras. Some of the time variability observed can be explained using the back-trajectories.

  7. [Determination of deuterium concentration in foods and influence of water with modified isotopic composition on oxidation parameters and heavy hydrogen isotopes content in experimental animals].

    Science.gov (United States)

    Basov, A A; Bykov, I M; Baryshev, M G; Dzhimak, S S; Bykov, M I

    2014-01-01

    The article presents the results of the study of the deuterium (D) content in food products as well as the influence of deuterium depleted water (DDW) on the concentration of heavy hydrogen isotopes in the blood and lyophilized tissues of rats. The most significant difference in the content of D was found between potato and pork fat, which indexes the standard delta notation (δ) D in promille, related to the international standard SMOW (Standard Mean Ocean of Water) amounted to -83,2 per thousand and -250,7 per thousand, respectively (phydrogen atoms in the body. The data obtained in the experimental modeling of the diet of male Wistar rats in the age of 5-6 mo (weight 235 ± 16 g) using DDW (δD = -743,2 per thousand) instead of drinking water (δD = -37,0 per thousand) with identical mineral composition showed that after 2 weeks significant (p tissue") is due to different rates ofisotopic exchange reactions in plasma and tissues (liver, kidney, heart), which can be explained by entering into the composition of a modified diet of organic substrates with more than DDW concentration D, which are involved in the construction of cellular structures and eventually lead to a redistribution of D and change direction of D/H gradient "plasmaisotopic composition, aimed at reducing the level of heavy non-radioactive atoms will allow the targeted nutritional correction of prooxidant-antioxidant status of the population in areas with adverse environmental conditions, stimulating by created isotopic D/H gradient cytoprotective mechanisms influencing the various components of nonspecific protection, including free radical oxidation processes. And then again, periodic assessment of the isotopic composition of nutrients will monitor the quality of food consumed by the population, and if

  8. A review of volatile compounds in tektites, and carbon content and isotopic composition of moldavite glass

    Czech Academy of Sciences Publication Activity Database

    Žák, Karel; Skála, Roman; Řanda, Zdeněk; Mizera, Jiří

    2012-01-01

    Roč. 47, č. 6 (2012), s. 1010-1028 ISSN 1086-9379 R&D Projects: GA ČR GA205/09/0991 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z10480505 Keywords : moldavites * geochemistry * ries * carbon stable isotopes * moldavites (Germany) Subject RIV: DD - Geochemistry Impact factor: 2.800, year: 2012

  9. The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile - Marine sources and diagenetic effects.

    Directory of Open Access Journals (Sweden)

    Friedrich Lucassen

    Full Text Available Seabird excrements (guano have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic

  10. The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile - Marine sources and diagenetic effects.

    Science.gov (United States)

    Lucassen, Friedrich; Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A

    2017-01-01

    Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very

  11. Stable isotope compositions of organic carbon and contents of organic carbon and nitrogen of lacustrine sediments from sub-arid northern Tanzania

    International Nuclear Information System (INIS)

    Muzuka, A.N.N.

    2006-01-01

    The stable isotope compositions of organic carbon (OC), and contents of OC and nitrogen for four sediment cores recovered from lakes Makat (located in the Ngorongoro Crater), Ndutu and Masek (located in the Serengeti Plains) are used to document sources of organic matter (OM) and climatic changes in sub-arid northern Tanzania during the late Pleistocene-Holocene period. Accelerate mass spectrometer (AMS) 14 C ages on total OM for sediments collected from the Ngorongoro Crater Lake indicate that the sedimentation rate is approximately 17 cm/ka. The δ 13 C values from the 20 cm long core (short core) show a downcore increase, whereas that of 500 cm long core (long core), show two peaks enriched in 13 C and three peaks depleted in 13 C. A general downcore increase in the δ 13 C values for the short core suggests changes in the relative proportion of C 3 and C 4 fraction increasing downcore. Similarly, low and high peaks in the long core suggest changes in the relative proportion of C 3 and C 4 with low values having high proportion of C 3 type of material, probably indicating changes in precipitation and lake levels in the area. Deposition of OM depleted in 13 C took place during periods of high precipitation and high lake levels. Although high content of OC and nitrogen in some core sections are associated with elevated C/N ratio values, diagenetic alteration of isotope signature is unlikely to have caused OC and isotope enrichment in sections having high contents of OC and nitrogen. The OC isotope record from Lake Ndutu shows a general downcore decrease in δ 13 C values and contents of OC and nitrogen. (author)

  12. Calcium isotopic composition of mantle peridotites

    Science.gov (United States)

    Huang, F.; Kang, J.; Zhang, Z.

    2015-12-01

    Ca isotopes are useful to decipher mantle evolution and the genetic relationship between the Earth and chondrites. It has been observed that Ca isotopes can be fractionated at high temperature [1-2]. However, Ca isotopic composition of the mantle peridotites and fractionation mechanism are still poorly constrained. Here, we report Ca isotope composition of 12 co-existing pyroxene pairs in 10 lherzolites, 1 harzburgite, and 1 wehrlite xenoliths collected from Hainan Island (South Eastern China). Ca isotope data were measured on a Triton-TIMS using the double spike method at the Guangzhou Institute of Geochemistry, CAS. The long-term external error is 0.12‰ (2SD) based on repeated analyses of NIST SRM 915a and geostandards. δ44Ca of clinopyroxenes except that from the wehrlite ranges from 0.85‰ to 1.14‰, while opx yields a wide range from 0.98‰ up to 2.16‰. Co-existing pyroxene pairs show large Δ44Caopx-cpx (defined as δ44Caopx-δ44Cacpx) ranging from 0 to 1.23‰, reflecting equilibrium fractionation controlled by variable Ca contents in the opx. Notably, clinopyroxene of wehrlite shows extremely high δ44Ca (3.22‰). δ44Ca of the bulk lherzolites and harzburgites range from 0.86‰ to 1.14‰. This can be explained by extracting melts with slightly light Ca isotopic compositions. Finally, the high δ44Ca of the wehrlite (3.22‰) may reflect metasomatism by melt which has preferentially lost light Ca isotopes due to chemical diffusion during upwelling through the melt channel. [1] Amini et al (2009) GGR 33; [2] Huang et al (2010) EPSL 292.

  13. Oxygen isotopic composition of the Luna 20 soil.

    Science.gov (United States)

    Clayton, R. N.

    1973-01-01

    Comparison of the oxygen isotopic composition in the Luna 20 soil sample with the oxygen isotopic abundances of the Apollo 11, 12, 14, and 15 lunar soil samples. The Luna 20 soil is found to have a relatively low delta 0-18 content (0.57%) in comparison to the other lunar soils (0.58 to 0.63%).

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

    Science.gov (United States)

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

    2017-12-01

    As a stable isotope, boron plays an important role in hydrogeology, environmental geochemistry, ore deposit geochemistry and marine paleoclimatology. However, there is no report of boron isotopic composition in gypsum. This is mainly confined to complete dissolution of Gypsum by water or acid. In this study, gypsum was converted to calcium carbonate (CaCO 3 ) with ammonium bicarbonate(NH 4 HCO 3 ) by two steps at 50°C. In every step, the mass ratio of NH 4 HCO 3 /CaSO 4 ·2H 2 O was twice, and conversion rate reached more than 98%. Converted CaCO 3 was totally dissolved with hydrochloric acid (the dissolution rate was over 99%). In order to overcome the difficulties of the matrix interference and the detection limit of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), we use Amberlite IRA 743 resin to purify and enrichment the boron at first, then eluting boron from the resin with 10mL 0.1mol/L hydrochloric acid at 75°C. The boron isotopic composition of natural gypsum samples was determined using positive thermal ionization mass spectrometry (P-TIMS). The boron isotopic composition of gypsum may be an excellent indicator for the formation environment. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Chemical production of chondrule oxygen isotopic composition

    Science.gov (United States)

    Thiemens, M. H.

    1994-01-01

    Defining the source of observed meteoritic O isotopic anomalies remains a fundamental challenge. The O isotopic composition of chondrules are particularly striking. There are at least three types of chemical processes that produce the isotopic compositions observed in chondrules and Ca-Al-rich inclusions (CAI's). The processes are rather general, viz, they require no specialized processes and the processes associated with chondrule production are likely to produce the observed compositions.

  16. On the Effect of Planetary Stable Isotope Compositions on Growth and Survival of Terrestrial Organisms.

    Directory of Open Access Journals (Sweden)

    Xueshu Xie

    Full Text Available Isotopic compositions of reactants affect the rates of chemical and biochemical reactions. Usually it is assumed that heavy stable isotope enrichment leads to progressively slower reactions. Yet the effect of stable isotopes may be nonlinear, as exemplified by the "isotopic resonance" phenomenon. Since the isotopic compositions of other planets of Solar system, including Mars and Venus, are markedly different from terrestrial (e.g., deuterium content is ≈5 and ≈100 times higher, respectively, it is far from certain that terrestrial life will thrive in these isotopic conditions. Here we found that Martian deuterium content negatively affected survival of shrimp in semi-closed biosphere on a year-long time scale. Moreover, the bacterium Escherichia coli grows slower at Martian isotopic compositions and even slower at Venus's compositions. Thus, the biological impact of varying stable isotope compositions needs to be taken into account when planning interplanetary missions.

  17. Isotopic composition of precipitation in Slovenia

    International Nuclear Information System (INIS)

    Vreca, P.; Kanduc, T.; Zigon, S.; Trkov, Z.

    2005-01-01

    Three-years monitoring of isotopic composition (δ 18 O, δ 2 H and 3 H) in precipitation in Slovenia was performed to obtain temporal and spatial variability and to trace changes of isotopic composition in W-E direction. Monthly as well as daily variations in isotopic composition were compared with climate-related parameters such as local air temperature and precipitation amount. Large variations in isotopic composition were observed especially during extremely dry year 2003. Relationships of δ 2 H vs. δ 18 O are close to the Global Meteoric Water Line with deviations related to the influence of different air masses and evaporation. Tritium activity distribution shows typical seasonal variations with winter concentrations approaching the natural pre-bomb level. (author)

  18. Isotopic composition of lead in soils and street dust in the Southeastern administrative district of Moscow

    Science.gov (United States)

    Ladonin, D. V.; Plyaskina, O. V.

    2009-01-01

    The content and isotope ratios of lead were studied in soils, street dust, and snow sampled in the Southeastern administrative district of Moscow. The relationships between the lead isotope ratios and the content of different lead compounds in soils were revealed. It was shown that isotope ratios for the total lead have low information values upon low levels of lead contamination. The contribution of technogenic lead compounds to the isotopic composition of lead increases in the following sequence: total lead < acid-soluble lead < mobile lead. The effect of emissions from thermal power stations and vehicles’ exhaust on the isotopic composition of lead in the street dust and soils was estimated.

  19. Content of lithium, beryllium, boron, and titanium, and the isotopic composition of lithium, boron, and magnesium in Luna 16 regolith sample

    Science.gov (United States)

    Eugster, O.

    1974-01-01

    The abundance of the following elements in the L 16-19 No. 118 regolith sample, zone V was determined by isotopic dilution using a mass spectrometer equipped with a scattering ion source: Li -- 9.8, Be -- 1.2, Be -- 2.6, and Ti -- 1.92 percent. For comparison, these same elements were measured in samples of surface material returned by Apollo 11, Apollo 12, and Apollo 14, and in the terrestrial reference standard diabase W-1. The content of Li, Be, and B in the Luna 16 sample is nearly the same as in the Apollo 11 surface material. The surface material returned by Apollo 12 and Apollo 14 contains two to four times more of these elements. However, the abundance ratios of Li, Be, and B are remarkably similar in the surface materials from the four different lunar regions. With respect to basaltic achondrites and especially with respect to chondrites, the lunar basalts are enriched in Li, Be, and B up to 100 times.

  20. Chemical and isotopic composition of precipitations in Syria

    International Nuclear Information System (INIS)

    Abou Zakhem, B.; Hafez, R.

    2007-05-01

    The objective of this study is to determine isotopic characteristics of precipitation, the climatic and geographical conditions affecting isotopic composition in order to obtain the input function of groundwater to evaluate the water resources.13 meteoric stations were selected in Syria for cumulative monthly rainfall sampling during two hydrological cycles; 1991-1992 and 1992-1993. The chemical and isotopic compositions of monthly precipitation were studied. The winter and spring rainfall isotopic characteristics were determined, in addition to the Syrian meteoric line (SMWL) was estimated with a slope of 6.62 and that of both Syria and Jordan of 6.73. The effect of climatic factors as temperature and relative air humidity on oxygen-18, deuterium and d-excess were studied and it was found that the relationship between temperature and oxygen-18 and deuterium is a positive linear correlation; however, it is a negative correlation with d-excess. The mean seasonal variation amplitude of 18 O was about 6%, and the amount effect on isotopic content of precipitation was studied. The geographic factors and its affect on isotopic contents of precipitation such as altitude were considered, furthermore, the isotopic gradient with altitude was determined for both oxygen-18 and deuterium (-0.14 % and -0.84% /100m respectively). The spatial distribution of oxygen-18, deuterium, tritium and d-excess indicted the effect of mountain chains and gaps between mountains on the isotopic content, the continental effect on tritium build-up by about 33% per 100 Km from the coast. The increase of d-excess values towards the south west proves the eastern Mediterranean climate type over this region.(author)

  1. Chemical and isotopic composition of precipitations in Syria

    International Nuclear Information System (INIS)

    Abou Zakhem, B.; Hafez, R.

    2008-01-01

    13 meteoric stations were selected in syria for cumulative monthly rainfall sampling during two hydrological cycles; 1991-1992 and 1992-1993. The chemical and isotopic compositions of monthly precipitation were studied. The winter and spring rainfall isotopic characteristics were determined, in addition to the syrian or local meteoric line (SMWL) was estimated with a slope of 6.63 and that of both syria and Jordan of 6.73. The effect of climatic factors as temperature and relative air humidity on oxygen-18, deuterium and d-excess were studied and it was found that the relationship between temperature and oxygen-18 and deuterium is a positive linear correlation; however, it is a negative correlation with d-excess. The mean seasonal variation amplitude was determined by 6%, and the amount effect on isotopic content of precipitation was studied. The geographic factors and its affect on isotopic contents of precipitation such as altitude were considered, furthermore, the isotopic gradient with altitude was determined for both oxygen-18 and deuterium (-0.14% and - 0.84%/100 m elevation respectively). The spatial variability of oxygen-18, deuterium, tritium and d-excess indicted the effect of mountain chains and gaps between mountains on the isotopic content of precipitation, the continental effect on tritium build-up by about 33% per 100 Km from the coast. The increase of d-excess values towards the south west proves the eastern mediterranean climate type over this region. (author)

  2. The carbon isotopic composition of ecosystem breath

    Science.gov (United States)

    Ehleringer, J.

    2008-05-01

    At the global scale, there are repeatable annual fluctuations in the concentration and isotopic composition of atmospheric carbon dioxide, sometimes referred to as the "breathing of the planet". Vegetation components within ecosystems fix carbon dioxide through photosynthesis into stable organic compounds; simultaneously both vegetation and heterotrophic components of the ecosystem release previously fixed carbon as respiration. These two-way fluxes influencing carbon dioxide exchange between the biosphere and the atmosphere impact both the concentration and isotopic composition of carbon dioxide within the convective boundary layer. Over space, the compounding effects of gas exchange activities from ecosystems become reflected in both regional and global changes in the concentration and isotopic composition of atmospheric carbon dioxide. When these two parameters are plotted against each other, there are significant linear relationships between the carbon isotopic composition and inverse concentration of atmospheric carbon dioxide. At the ecosystem scale, these "Keeling plots" intercepts of C3-dominated ecosystems describe the carbon isotope ratio of biospheric gas exchange. Using Farquhar's model, these carbon isotope values can be translated into quantitative measures of the drought-dependent control of photosynthesis by stomata as water availability changes through time. This approach is useful in aggregating the influences of drought across regional landscapes as it provides a quantitative measure of stomatal influence on photosynthetic gas exchange at the ecosystem-to-region scales. Multi-year analyses of the drought-dependent trends across terrestrial ecosystems show a repeated pattern with water stress in all but one C3-ecosystem type. Ecosystems that are dominated by ring-porous trees appear not to exhibit a dynamic stomatal response to water stress and therefore, there is little dependence of the carbon isotope ratio of gas exchange on site water balance

  3. Spectral determination of thallium isotope composition

    International Nuclear Information System (INIS)

    Polyanskij, V.A.; Turkin, Yu.I.; Yakimova, N.M.

    1986-01-01

    The photoelectric non-standard method for determination of the thallium isotope composition is developed. The analysis is carried out by measuring the brightness of the Hfs components in the line Tl Iλ535.04 nm. The relative standard deviation of the results of the isotope analysis of thallium as metal is 0.02 and of thallium salts - 0.02-0.05

  4. Influence of chemical structure on carbon isotope composition of lignite

    Science.gov (United States)

    Erdenetsogt, Bat-Orshikh; Lee, Insung; Ko, Yoon-Joo; Mungunchimeg, Batsaikhan

    2017-04-01

    During the last two decades, a number of studies on carbon isotopes in terrestrial organic matter (OM) have been carried out and used to determine changes in paleoatmospheric δ13C value as well as assisting in paleoclimate analysis. Coal is abundant terrestrial OM. However, application of its δ13C value is very limited, because the understanding of changes in isotopic composition during coalification is relatively insufficient. The purpose of this study was to examine the influence of the chemical structure on the carbon isotope composition of lignite. Generally, lignite has more complex chemical structures than other higher rank coal because of the existence of various types of oxygen-containing functional groups that are eliminated at higher rank level. A total of sixteen Lower Cretaceous lignite samples from Baganuur mine (Mongolia) were studied by ultimate, stable carbon isotope and solid-state 13C CP/MAS NMR analyses. The carbon contents of the samples increase with increase in depth, whereas oxygen content decreases continuously. This is undoubtedly due to normal coalification process and also consistent with solid state NMR results. The δ13C values of the samples range from -23.54‰ to -21.34‰ and are enriched in 13C towards the lowermost samples. Based on the deconvolution of the NMR spectra, the ratios between carbons bonded to oxygen (60-90 ppm and 135-220 ppm) over carbons bonded to carbon and hydrogen (0-50 ppm and 90-135 ppm) were calculated for the samples. These correlate well with δ13C values (R2 0.88). The results indicate that the δ13C values of lignite are controlled by two mechanisms: (i) depletion in 13C as a result of loss of isotopically heavy oxygen-bounded carbons and (ii) enrichment in 13C caused by a loss of isotopically light methane from aliphatic and aromatic carbons. At the rank of lignite, coal is enriched in 13C because the amount of isotopically heavy CO2 and CO, released from coal as a result of changes in the chemical

  5. Calcium Isotopic Composition of Bulk Silicate Earth

    Science.gov (United States)

    Kang, J.; Ionov, D. A.; Liu, F.; Zhang, C.; Zhang, Z.; Huang, F.

    2016-12-01

    Ca isotopes are used to study the accretion history of the Earth and terrestrial planets, but, Ca isotopic composition of the Bulk Silicate Earth (BSE) remains poorly constrained [1]. To better understand the Ca isotopic composition of BSE, we analyzed 22 well studied peridotite xenoliths from Tariat (Mongolia), Vitim (southern Siberia) and Udachnaya (Siberian Craton). These samples include both fertile and highly depleted garnet and spinel peridotites that show no or only minor post-melting metasomatism or alteration. Ca isotope measurements were done on a Triton-TIMS using double spike method at the Guangzhou Institute of Geochemistry, CAS. The data are reported as δ44/40Ca (relative to NIST SRM 915a). Results for geostandards are consistent with those from other laboratories. 2 standard deviations of SRM 915a analyses are 0.13‰ (n=48). δ44/40Ca of both and fertile and refractory peridotites range from 0.79 to 1.07‰ producing an average of 0.93±0.12‰ (2SD). This value defines the Ca isotopic composition of the BSE, which is consistent with the average δ44/40Ca of oceanic basalts ( 0.90‰)[2,3]. [1] Huang et al (2010) EPSL 292; [2] Valdes et al (2014) EPSL 394; [3]DePaolo (2004) RMG 55.

  6. Separation of compounds differing in isotopic composition

    International Nuclear Information System (INIS)

    Sievers, R.E.; Brooks, J.J.

    1976-01-01

    Compounds differing in isotopic composition are separated by introducing a mixture of the compounds into a chromatographic column containing a lanthanide chelate as a stationary phase and eluting from the column a fraction which is at least enriched with one of the compounds of the mixture. 17 claims, no drawings

  7. Petrography, compositional characteristics and stable isotope ...

    African Journals Online (AJOL)

    Petrography, compositional characteristics and stable isotope geochemistry of the Ewekoro formation from Ibese Corehole, eastern Dahomey basin, southwestern Nigeria. ME Nton, MO ... Preserved pore types such as; intercrystaline, moldic and vuggy pores were observed as predominant conduits for fluids. The major ...

  8. petrography, compositional characteristics and stable isotope ...

    African Journals Online (AJOL)

    PROF EKWUEME

    Subsurface samples of the predominantly carbonate Ewekoro Formation, obtained from Ibese core hole within the Dahomey basin were used in this study. Investigations entail petrographic, elemental composition as well as stable isotopes (carbon and oxygen) geochemistry in order to deduce the different microfacies and ...

  9. Separation of compounds differing in isotopic composition

    International Nuclear Information System (INIS)

    Sievers, R.E.; Brooks, J.J.

    1975-01-01

    Compounds differing in isotopic composition are separated by introducing a mixture of the compounds into a chromatographic column containing a lanthanide chelate as a stationary phase and eluting from the column a fraction that is at least enriched with one of the compounds of the mixture. (U.S.)

  10. Facies, dissolution seams and stable isotope compositions

    Indian Academy of Sciences (India)

    Stable isotope analysis of the limestone shows that 13C and 18O values are compatible with the early Mesoproterozoic open seawater composition. The ribbon limestone facies in the Rohtas Limestone is characterized by micritic beds, each decoupled in a lower band enriched and an upper band depleted in dissolution ...

  11. Isotopic compositions of boron in sediments and their implications

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Yingkai, X.

    The abundance and isotopic compositions of boron in sediments from the salt lakes of Qaidam Basin, China have been determined by thermal ionization mass spectrometry of cesium borate. The results show large variations in the isotopic compositions...

  12. Variation in the isotopic content of precipitation with altitude

    International Nuclear Information System (INIS)

    Stowhas, L.; Silva, C.; Moser, H.; Stichler, W.

    1975-03-01

    Monthly precipitation and single storms have been collected during three years at 12 stations along a W-E profile in Chile, going from Juan Fernandez Islands to Valparaiso, Santiago and Infiernillo in the Andes, and analysed for their deuterium content. The deltaD values are correlated with the altitude of the station, the mean temperature - which also largely depends on the altitude - and the distance from the sea. The correlation parameters show however important variations from year to year and even more from month to month. For instance, in the stretch Santiago (520 m a.s.l.) - La Parva (2680 m) the mean isotopic gradient with altitude were: -1.84 deltaD per mil/100 m in 1970, -1.09 in 1971 and -2.0 in 1972. The low value observed in 1971 could be a consequence of the peculiar weather characteristics of this unusually dry year. In the stretch from the coast to Santiago the trend of the isotopic composition of precipitation is more complicated, because the so-called continental effect is superimposed to the altitude effect. The deuterium content variations have been also determined in snowpack profiles at La Parva station. The results show that snow melting occurs slowly at the bottom during the whole winter, at the expenses of the heat stored during summer in the soil. The melting of the surface snow layers only starts at the end of the winter and then proceeds very fast

  13. Tungsten Stable Isotope Compositions of Ferromanganese Crusts

    Science.gov (United States)

    Abraham, K.; Barling, J.; Hein, J. R.; Schauble, E. A.; Halliday, A. N.

    2014-12-01

    We report the first accurate and precise data for mass-dependent fractionation of tungsten (W) stable isotopes, using a double spike technique and MC-ICPMS. Results are expressed relative to the NIST 3136 W isotope standard as per mil deviations in 186W/184W (δ186W). Although heavy element mass-dependent fractionations are expected to be small, Tl and U both display significant low temperature isotopic fractionations. Theoretical calculations indicate that W nuclear volume isotopic effects should be smaller than mass-dependent fractionations at low temperatures. Hydrogenetic ferromanganese (Fe-Mn) crusts precipitate directly from seawater and have been used as paleoceanographic recorders of temporal changes in seawater chemistry. Crusts are strongly enriched in W and other metals, and are a promising medium for exploring W isotopic variability. Tungsten has a relatively long residence time in seawater of ~61,000 years, mainly as the tungstate ion (WO42-). Water depth profiles show conservative behaviour. During adsorption on Fe-Mn crusts, W species form inner-sphere complexes in the hexavalent (W6+) state. The major host phase is thought to be Mn oxides and the lighter W isotope is expected to be absorbed preferentially. Surface scrapings of 13 globally distributed hydrogenetic Fe-Mn crusts display δ186W from -0.08 to -0.22‰ (±0.03‰, 2sd). A trend toward lighter W isotope composition exists with increasing water depth (~1500 to ~5200m) and W concentration. One hydrothermal Mn-oxide sample is anomalously light and Mn nodules are both heavy and light relative to Fe-Mn crusts. Tungsten speciation depends on concentration, pH, and time in solution and is not well understood because of the extremely slow kinetics of the reactions. In addition, speciation of aqueous and/or adsorbed species might be sensitive to pressure, showing similar thermodynamic stability but different effective volumes. Thus, W stable isotopes might be used as a water-depth barometer in

  14. Tracing anthropogenic thallium in soil using stable isotope compositions.

    Science.gov (United States)

    Kersten, Michael; Xiao, Tangfu; Kreissig, Katharina; Brett, Alex; Coles, Barry J; Rehkämper, Mark

    2014-08-19

    Thallium stable isotope data are used in this study, for the first time, to apportion Tl contamination in soils. In the late 1970s, a cement plant near Lengerich, Germany, emitted cement kiln dust (CKD) with high Tl contents, due to cocombustion of Tl-enriched pyrite roasting waste. Locally contaminated soil profiles were obtained down to 1 m depth and the samples are in accord with a binary mixing relationship in a diagram of Tl isotope compositions (expressed as ε(205)Tl, the deviation of the (205)Tl/(203)Tl ratio of a sample from the NIST SRM 997 Tl isotope standard in parts per 10(4)) versus 1/[Tl]. The inferred mixing endmembers are the geogenic background, as defined by isotopically light soils at depth (ε(205)Tl ≈ -4), and the Tl emissions, which produce Tl-enriched topsoils with ε(205)Tl as high as ±0. The latter interpretation is supported by analyses of the CKD, which is also characterized by ε(205)Tl ≈ ± 0, and the same ε(205)Tl value was found for a pyrite from the deposit that produced the cocombusted pyrite roasting waste. Additional measurements for samples from a locality in China, with outcrops of Tl sulfide mineralization and associated high natural Tl backgrounds, reveal significant isotope fractionation between soils (ε(205)Tl ≈ +0.4) and locally grown green cabbage (ε(205)Tl between -2.5 and -5.4). This demonstrates that biological isotope fractionation cannot explain the isotopically heavy Tl in the Lengerich topsoils and the latter are therefore clearly due to anthropogenic Tl emissions from cement processing. Our results thus establish that isotopic data can reinforce receptor modeling for the toxic trace metal Tl.

  15. Isotopic Composition of Oxygen in Lunar Zircons

    Science.gov (United States)

    Nemchin, A. A.; Whitehouse, M. J.; Pidgeon, R. T.; Meyer, C.

    2005-01-01

    The recent discovery of heavy oxygen in zircons from the Jack Hills conglomerates Wilde et al. and Mojzsis et al. was interpreted as an indication of presence of liquid water on the surface of Early Earth. The distribution of ages of Jack Hills zircons and lunar zircons appears to be very similar and therefore analysis of oxygen in the lunar grains may provide a reference frame for further study of the early history of the Earth as well as give additional information regarding processes that operated on the Moon. In the present study we have analysed the oxygen isotopic composition of zircon grains from three lunar samples using the Swedish Museum of Natural History CAMECA 1270 ion microprobe. The samples were selected as likely tests for variations in lunar oxygen isotopic composition. Additional information is included in the original extended abstract.

  16. The Nitrogen Isotopic Composition of Meteoritic HCN

    Science.gov (United States)

    Pizzarello, Sandra

    2014-12-01

    HCN is ubiquitous in extraterrestrial environments and is central to current theories on the origin of early solar system organic compounds such as amino acids. These compounds, observed in carbonaceous meteorites, were likely important in the origin and/or evolution of early life. As part of our attempts to understand the origin(s) of meteoritic CN-, we have analyzed the 15N/14N isotopic composition of HCN gas released from water extracts of the Murchison meteorite and found its value to be near those of the terrestrial atmosphere. The findings, when evaluated viz-a-viz molecular abundances and isotopic data of meteoritic organic compounds, suggest that HCN formation could have occurred during the protracted water alteration processes known to have affected the mineralogy of many asteroidal bodies during their solar residence. This was an active synthetic stage, which likely involved simple gasses, organic molecules, their presolar precursors, as well as mineral catalysts and would have lead to the formation of molecules of differing isotopic composition, including some with solar values.

  17. Element isotope composition definition in solid microvolumes

    International Nuclear Information System (INIS)

    Kaviladze, M.Sh.; Melashvili, T.A.; Kviriya, M.S.

    1977-01-01

    A method for the mass-spectrometric isotopic analysis of solid microvolumes is described which allows to obtain both high analysis localization and high accuracy of the results. The underlying idea is that a laser beam is used to transfer the sample layer-wise onto the evaporator film directly in the ion source. To effect this mass-spectrometric analysis an apparatus has been developed comprising a mass-spectrometer, a ruby laser, a feedback circuit from the amplifier of the ion current of a more common isotope and a replaceable-vaporizer ion source. The composition of each microvolume having a mass about 10 -13 g. is measured in relation to the model specimen, whereby a relative measurement accuracy of about 0.1% is achieved

  18. Alkali elemental and potassium isotopic compositions of Semarkona chondrules

    Science.gov (United States)

    Alexander, C.M. O'D.; Grossman, J.N.

    2005-01-01

    We report measurements of K isotope ratios in 28 Semarkona chondrules with a wide range of petrologic types and bulk compositions as well as the compositions of CPX-mesostasis pairs in 17 type I Semarkona chondrules, including two chondrules with radial alkali zonation and 19 type II chondrules. Despite the wide range in K/Al ratios, no systematic variations in K isotopic compositions were found. Semarkona chondrules do not record a simple history of Rayleigh-type loss of K. Experimentally determined evaporation rates suggest that considerable alkali evaporation would have occurred during chondrule formation. Nevertheless, based on Na CPX-mesostasis distribution coefficients, the alkali contents of the cores of most chondrules in Semarkona were probably established at the time of final crystallization. However, Na CPX-mesostasis distribution coefficients also show that alkali zonation in type I Semarkona chondrules was produced by entry of alkalis after solidification, probably during parent body alteration. This alkali metasomatism may have gone to completion in some chondrules. Our preferred explanation for the lack of systematic isotopic enrichments, even in alkali depleted type I chondrule cores, is that they exchanged with the ambient gas as they cooled. ?? The Meteoritical Society, 2005.

  19. Life support systems and optimal isotope composition in cosmonaut habitats for long-term missions

    Science.gov (United States)

    Siniak, I. E.; Grigoriev, A. I.

    Differences in the isotope content of the biogenous chemicals of cosmonaut habitats are given a theoretical consideration. Rationale is given to the hypothesis according to which the biochemical and biophysical processes in plants, animals, and humans must be impacted by the isotopes of all the biogenous chemicals in cosmonaut habitats. Organisms were found to persistently make preference of lighter fractions of stable isotopes from the biogenous chemicals. In most of the compounds the light fraction of stable isotopes constitutes the greater portion by mass. However, the optimal isotope composition of biogenous chemicals is still unknown and necessitates biochemical, toxicological, biological and other kinds of research. The functions of a life support system should also include production and maintenance of an optimal isotope composition for habitats, i.e. water, oxygen, food stuffs in order to improve metabolism in and performance of cosmonauts.

  20. Proximate composition and antinutrient content of pumpkin ...

    African Journals Online (AJOL)

    Proximate composition and antinutrient content of pumpkin ( Cucurbita pepo ) and sorghum ( Sorghum bicolor ) flour blends fermented with Lactobacillus plantarum , Aspergillus niger and Bacillus subtilis.

  1. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Directory of Open Access Journals (Sweden)

    M. Bolot

    2013-08-01

    Full Text Available The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen process. As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  2. Oxygen isotopic compositions of chondrules in Allende and ordinary chondrites

    Science.gov (United States)

    Clayton, R. N.; Mayeda, T. K.; Hutcheon, I. D.; Molini-Velsko, C.; Onuma, N.; Ikeda, Y.; Olsen, E. J.

    1983-01-01

    The ferromagnesian chondrules in Allende follow a trend in the oxygen three-isotope plot that diverges significantly from the 16-O mixing line defined by light and dark inclusions and the matrix of the meteorite. The trend probably results from isotopic exchange with an external gaseous reservoir during the process of chondrule formation sometime after the establishment of the isotopic compositions of the inclusions and matrix. The Allende chondrules approach, but do not reach, the isotopic compositions of chondrules in unequilibrated ordinary chondrites, implying exchange with a similar ambient gas, but isotopically different solid precursors for the two types of meteorite.

  3. Isotopic composition of precipitation and groundwater in Sicily, Italy

    International Nuclear Information System (INIS)

    Liotta, M.; Grassa, F.; D’Alessandro, W.; Favara, R.; Gagliano Candela, E.; Pisciotta, A.; Scaletta, C.

    2013-01-01

    Highlights: • Isotopic composition of precipitation and groundwater in Sicily (Italy). • Isotopic data processing for hydrogeological purpose. • GIS mapping of isotopic data. - Abstract: The isotopic composition of meteoric water in Sicily, Italy was investigated from May 2004 until June 2006. Samples were sampled monthly from a network of 50 rain gauges. During the same period 580 groundwater samples were collected from springs and wells to obtain insight into the isotopic composition of the water circulating in the main aquifers of the area. The mean weighted precipitation values were used to define the weighted local meteoric water line for five different sectors of Sicily. The use of Geographical Information System tools, coupled with isotopic vertical gradients, allowed designing an isotopic contour map of precipitation in Sicily. The defined meteoric compositions were highly consistent with most of the groundwater samples in each sector. However, in some areas fractionation processes occurring during and after rainfall slightly modify the isotopic composition of the groundwater. The obtained data set defines the present day isotopic composition of meteoric water in the central Mediterranean area and provides baseline values for future climatic and/or isotope-based hydrology studies

  4. Stable isotope content of South African river water

    International Nuclear Information System (INIS)

    Talma, A.S.

    1987-01-01

    Variations of the isotopic ratios 18 O/ 16 O and D/H in natural waters reflect the variety of processes to which the water was subjected within the hydrological cycle. Time series of the 18 O content of the major South African rivers over a few years have been obtained in order to characterise the main features of these variations in both time and space. Regionally the average '1 8 O content of river water reflects that of the prevailing rains within the catchment. 18 O variations with time are mainly correlated with river flow rates. Impoundments upstream and management of river flows reduce this correlation. Isotope variations along the course of a river show the effects of inflow from smaller streams and evaporation in the river or its impoundments. These observations indicate the use of isotopic methods to study the evaporation and mixing of river water and its interaction with the surrounding environment

  5. Isotopic composition of Danube water in the pre-delta section from the years 2009 - 2012

    Directory of Open Access Journals (Sweden)

    RANK Dieter

    2013-12-01

    Full Text Available The isotopic composition of river water in the Danube Basin is mainly governed by the isotopic composition of precipitation in the catchment area, evaporation effects play only a minor role. Short-term and long-term isotope signals from precipitation are thus transmitted through the whole catchment. The isotopic composition of Danube water in the Delta region so provides an integrated isotope signal for climatic/hydrological conditions and changes in the whole catchment. The aim of this investigation was to establish a representative isotope monitoring near the Danube Delta. The results showed that the Danube River is regarding isotope content fully mixed at the bifurcation of the Danube Delta arms. Therefore routine sampling at only one location in the pre-delta region should be sufficient to obtain a representative isotope record for the whole Danube Basin. The δ 18 O time series from November 2009 to May 2012 (sampling twice a month shows seasonal variations in the range of -9.8 ‰ ± 0.7 ‰ with a minimum in spring and a maximum in autumn. The tritium results exhibit the influence of short term contaminations due to human activities. The expected “environmental” tritium content of river water in Central Europe would be about 10 TU. During this investigation 3 H values up to 100 TU were observed in the pre-delta section. This indicates short terms releases of tritium from local sources such as nuclear power plants in the Danube river system.

  6. Oxygen isotope composition of mafic magmas at Vesuvius

    Science.gov (United States)

    Dallai, L.; Cioni, R.; Boschi, C.; D'Oriano, C.

    2009-12-01

    The oxygen isotope composition of olivine and clinopyroxene from four plinian (AD 79 Pompeii, 3960 BP Avellino), subplinian (AD 472 Pollena) and violent strombolian (Middle Age activity) eruptions were measured to constrain the nature and evolution of the primary magmas of the last 4000 years of Mt. Vesuvius activity. A large set of mm-sized crystals was accurately separated from selected juvenile material of the four eruptions. Crystals were analyzed for their major and trace element compositions (EPMA, Laser Ablation ICP-MS), and for 18O/16O ratios. As oxygen isotope composition of uncontaminated mantle rocks on world-wide scale is well constrained (δ18Oolivine = 5.2 ± 0.3; δ18Ocpx = 5.6 ± 0.3 ‰), the measured values can be conveniently used to monitor the effects of assimilation/contamination of crustal rocks in the evolution of the primary magmas. Instead, typically uncontaminated mantle values are hardly recovered in Italian Quaternary magmas, mostly due to the widespread occurrence of crustal contamination of the primary magmas during their ascent to the surface (e.g. Alban Hills, Ernici Mts., and Aeolian Islands). Low δ18O values have been measured in olivine from Pompeii eruption (δ18Oolivine = 5.54 ± 0.03‰), whereas higher O-compositions are recorded in mafic minerals from pumices or scoria of the other three eruptions. Measured olivine and clinopyroxene share quite homogeneous chemical compositions (Olivine Fo 85-90 ; Diopside En 45-48, respectively), and represent phases crystallized in near primary mafic magmas, as also constrained by their trace element compositions. Data on melt inclusions hosted in crystals of these compositions have been largely collected in the past demonstrating that they crystallized from mafic melt, basaltic to tephritic in composition. Published data on volatile content of these melt inclusions reveal the coexistence of dissolved water and carbon dioxide, and a minimum trapping pressure around 200-300 MPa, suggesting

  7. Integrating stomach content and stable isotope analyses to quantify the diets of pygoscelid penguins.

    Directory of Open Access Journals (Sweden)

    Michael J Polito

    Full Text Available Stomach content analysis (SCA and more recently stable isotope analysis (SIA integrated with isotopic mixing models have become common methods for dietary studies and provide insight into the foraging ecology of seabirds. However, both methods have drawbacks and biases that may result in difficulties in quantifying inter-annual and species-specific differences in diets. We used these two methods to simultaneously quantify the chick-rearing diet of Chinstrap (Pygoscelis antarctica and Gentoo (P. papua penguins and highlight methods of integrating SCA data to increase accuracy of diet composition estimates using SIA. SCA biomass estimates were highly variable and underestimated the importance of soft-bodied prey such as fish. Two-source, isotopic mixing model predictions were less variable and identified inter-annual and species-specific differences in the relative amounts of fish and krill in penguin diets not readily apparent using SCA. In contrast, multi-source isotopic mixing models had difficulty estimating the dietary contribution of fish species occupying similar trophic levels without refinement using SCA-derived otolith data. Overall, our ability to track inter-annual and species-specific differences in penguin diets using SIA was enhanced by integrating SCA data to isotopic mixing modes in three ways: 1 selecting appropriate prey sources, 2 weighting combinations of isotopically similar prey in two-source mixing models and 3 refining predicted contributions of isotopically similar prey in multi-source models.

  8. Carbon and Oxygen isotopic composition in paleoenvironmental determination

    International Nuclear Information System (INIS)

    Silva, J.R.M. da.

    1978-01-01

    This work reports that the carbon and oxygen isotopic composition separate the mollusks from marine environment of the mollusks from continental environment in two groups isotopically different, making the biological control outdone by environment control, in the isotopic fragmentation mechanisms. The patterns from the continental environment are more rich in O 16 than the patterns from marine environments. The C 12 is also more frequent in the mollusks from continental environments. The carbon isotopic composition in paterns from continental environments is situated betwen - 10.31 and - 4,05% and the oxygen isotopic composition is situated between - 6,95 and - 2,41%. To the marine environment patterns the carbon isotopic composition is between - 2,08 and + 2,65% and the oxigen isotopic composition is between - 2,08 and + 0,45%. Was also analysed fossil marine mollusks shells and their isotopic composition permit the formulation of hypothesis about the environment which they lived. (C.D.G.) [pt

  9. Phytochemical composition, total phenolic content and ferric ...

    African Journals Online (AJOL)

    The increased interest in discovering drugs from natural source led to the investigation of the phytochemical composition, the total phenolic content (TPC) and ferric reducing antioxidant power (FRAP) of leaf, stem and root bark extracts of S. sarmentosus DC. The total phenolic content of the extracts were examined using ...

  10. Elemental and iron isotopic composition of aerosols collected in a parking structure

    International Nuclear Information System (INIS)

    Majestic, Brian J.; Anbar, Ariel D.; Herckes, Pierre

    2009-01-01

    The trace metal contents and iron isotope composition of size-resolved aerosols were determined in a parking structure in Tempe, AZ, USA. Particulate matter (PM) 2.5 μm were collected. Several air toxics (e.g., arsenic, cadmium, and antimony) were enriched above the crustal average, implicating automobiles as an important source. Extremely high levels of fine copper (up to 1000 ng m -3 ) were also observed in the parking garage, likely from brake wear. The iron isotope composition of the aerosols were found to be + 0.15 ± 0.03 per mille and + 0.18 ± 0.03 per mille for the PM 2.5 μm fractions, respectively. The similarity of isotope composition indicates a common source for each size fraction. To better understand the source of iron in the parking garage, the elemental composition in four brake pads (two semi-metallic and two ceramic), two tire tread samples, and two waste oil samples were determined. Striking differences in the metallic and ceramic brake pads were observed. The ceramic brake pads contained 10-20% copper by mass, while the metallic brake pads contained about 70% iron, with very little copper. Both waste oil samples contained significant amounts of calcium, phosphorous, and zinc, consistent with the composition of some engine oil additives. Differences in iron isotope composition were observed between the source materials; most notably between the tire tread (average = + 0.02 per mille ) and the ceramic brake linings (average = + 0.65 per mille ). Differences in isotopic composition were also observed between the metallic (average = + 0.18 per mille ) and ceramic brake pads, implying that iron isotope composition may be used to resolve these sources. The iron isotope composition of the metallic brake pads was found to be identical to the aerosols, implying that brake dust is the dominant source of iron in a parking garage.

  11. Isotopic Composition of Xenon in Petroleum from the Shell ...

    Indian Academy of Sciences (India)

    The xenon isotopic composition was found to be similar to the atmospheric value for one petroleum sample. While the results of the second sample suggest possible enrichment of the heavier isotopes, the errors associated with these excesses preclude a definitive statement to that effect. No monoisotopic enrichment in ...

  12. A comparative study on isotopic composition of precipitation in wet ...

    Indian Academy of Sciences (India)

    A comparative study on isotopic composition of precipitation in wet tropic and semi-arid stations across southern India. C Unnikrishnan Warrier∗ and M Praveen Babu. Isotope Hydrology Division, Centre for Water Resources Development and Management,. Kunnamangalam P.O., Kozhikode 673 571, Kerala, India. ∗.

  13. The isotopic composition of CO in vehicle exhaust

    NARCIS (Netherlands)

    Naus, S.; Röckmann, T.; Popa, M.E.

    2018-01-01

    We investigated the isotopic composition of CO in the exhaust of individual vehicles. Additionally, the CO 2 isotopes, and the CO:CO 2 , CH 4 :CO 2 and H 2 :CO gas ratios were measured. This was done under idling and revving conditions, and for three vehicles in a full driving cycle on a testbench.

  14. The oxygen isotopic composition of water extracted from carbonaceous chondrites

    OpenAIRE

    Baker, L.; Franchi, Ian; Wright, Ian; Pillinger, Colin

    2001-01-01

    The oxygen isotopic composition of water from carbonaceous chondrites suggests that close to isotopic equilibrium was attained on CI and CM parent bodies. This is more consistent with a closed system than one with fluid flow. Tagish Lake does not display such equilibrium.

  15. Essential oil content and composition of aniseed

    Directory of Open Access Journals (Sweden)

    Aćimović Milica G.

    2015-01-01

    Full Text Available The field experiments were carried out during 2011 and 2012 in three localities in Vojvodina (Serbia with the application of six different fertilizer regimes aimed at determining the content and composition of the aniseed essential oil. It was found that the average essential oil content of aniseed, obtained by hydrodistillation, was 3.72%. The weather conditions during the year and the locality had a statistically significant effect on the essential oil content, while different source of fertilizers was not statistically significant for the essential oil content and its composition. Essential oil composition was determined using GC-MS technique, and a total of 15 compounds were identified. It was found that the major component was trans-anethole, 94.78% on the average, and the coefficient of variation was 2%. The second most abundant component was γ-himachalene with 2.53% (CV 28%. All other components were present in less than 1%.

  16. Review of data of oxygen and hydrogen isotope composition in thermal waters in China

    International Nuclear Information System (INIS)

    Fan Zhicheng; Wang Jiyang

    1988-01-01

    Based on the data of δD and δ 18 O content from more than 600 water samples, this paper reviews the stable isotope composition of thermal waters in China. Data to be used in this paper were mostly collected from published literatures with a few by authors. 9 figs, 2 tabs

  17. Isotopic compositions of the elements 2013 (IUPAC Technical Report)

    Science.gov (United States)

    Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna; Loss, Robert D.; Walczyk, Thomas; Prohaska, Thomas

    2016-01-01

    The Commission on Isotopic Abundances and Atomic Weights (ciaaw.org) of the International Union of Pure and Applied Chemistry (iupac.org) has revised the Table of Isotopic Compositions of the Elements (TICE). The update involved a critical evaluation of the recent published literature. The new TICE 2013 includes evaluated data from the “best measurement” of the isotopic abundances in a single sample, along with a set of representative isotopic abundances and uncertainties that accommodate known variations in normal terrestrial materials.

  18. Joint composite-rotation adiabatic-sweep isotope filtration

    International Nuclear Information System (INIS)

    Valentine, Elizabeth R.; Ferrage, Fabien; Massi, Francesca; Cowburn, David; Palmer, Arthur G.

    2007-01-01

    Joint composite-rotation adiabatic-sweep isotope filters are derived by combining the composite-rotation [Stuart AC et al. (1999) J Am Chem Soc 121: 5346-5347] and adiabatic-sweep [Zwahlen C et al. (1997) J Am Chem Soc 119:6711-6721; Kupce E, Freeman R (1997) J Magn Reson 127:36-48] approaches. The joint isotope filters have improved broadband filtration performance, even for extreme values of the one-bond 1 H- 13 C scalar coupling constants in proteins and RNA molecules. An average Hamiltonian analysis is used to describe evolution of the heteronuclear scalar coupling interaction during the adiabatic sweeps within the isotope filter sequences. The new isotope filter elements permit improved selective detection of NMR resonance signals originating from 1 H spins attached to an unlabeled natural abundance component of a complex in which the other components are labeled with 13 C and 15 N isotopes

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

    Science.gov (United States)

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

    2011-05-01

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

  20. Changes in stable isotope composition in Lake Michigan trout ...

    Science.gov (United States)

    Researchers have frequently sought to use environmental archives of sediment, peat and glacial ice to try and assess historical trends in atmospheric mercury (Hg) deposition to aquatic ecosystems. While this information is valuable in the context of identifying temporal source trends, these types of assessments cannot account for likely changes in bioavailability of Hg sources that are tied to the formation of methylmercury (MeHg) and accumulation in fish tissues. For this study we propose the use of long-term fish archives and Hg stable isotope determination as an improved means to relate temporal changes in fish Hg levels to varying Hg sources in the Great Lakes. For this study we acquired 180 archived fish composites from Lake Michigan over a 40-year time period (1975 to 2014) from the Great Lakes Fish Monitoring and Surveillance Program, which were analyzed for their total Hg content and Hg isotope abundances. The results reveal that Hg sources to Lake Michigan trout (Salvelinus namaycush) have encountered considerable changes as well as a large shift in the food web trophic position as a result of the introduction of several invasive species, especially the recent invasion of dreissenid mussels. Total Hg concentrations span a large range (1,600 to 150 ng g-1) and exhibit large variations from 1975 to 1985. Ä199Hg signatures similarly exhibit large variation (3.2 to 6.9‰) until 1985, followed by less variation through the end of the data record in 2014.

  1. Chromium isotope composition of reducing and anoxic sediments from the Peru Margin and Cariaco Basin

    Science.gov (United States)

    Gueguen, B.; Planavsky, N.; Wang, X.; Algeo, T. J.; Peterson, L. C.; Reinhard, C. T.

    2014-12-01

    Chromium isotope systematics in marine sediments are now being used as a new redox proxy of the modern and ancient Earth's surface. Chromium is primarily delivered to the oceans by riverine inputs through weathering of Cr(III)-rich minerals present in the continental crust and oxidation of insoluble Cr(III) to soluble Cr(VI) species. Since oxidation-reduction reactions fractionate Cr isotopes whereby oxidized Cr(VI) species are preferentially enriched in heavy Cr isotopes, the Cr isotope composition of marine sediments may be useful tracers of redox conditions at the Earth's surface through geological time. Chromium is quantitatively removed in organic-rich sediments where reducing conditions prevail and promote reduction of Cr(VI) to Cr(III), and thus, these sediments should capture the ambient seawater Cr isotope composition. However, the isotopic composition of modern organic-rich sediments is poorly documented so far, and this step is essential for further modeling the global oceanic Cr isotope mass balance and assessing the effects of sedimentation and post-depositional processes on the marine Cr isotopes archive. In this study, we have characterized modern marine organic-rich sediments for their Cr isotope composition (δ53/52Cr) from two different settings, the Peru margin upwelling zone and the anoxic Cariaco Basin (Venezuela). Chromium isotopes were measured on a MC-ICP-MS (Nu Plasma) using a double-spike correction method. The authigenic fraction of shallow samples from the Peru margin sedimentary sequence with a high Total Organic Carbon (TOC) content (>10 wt%) yield an average δ53/52Crauthigenic value of +0.67 ±0.05 ‰ (2sd). However, although this value is close to the seawater value (Atlantic Ocean) and to Cariaco basin sediments (~ +0.6 ‰), reducing sediments from the Peru margin are on average isotopically slightly heavier, especially in samples having a low authigenic fraction and a low TOC content (δ53/52Crauthigenic values up to +1.30

  2. What does the oxygen isotope composition of rodent teeth record?

    Science.gov (United States)

    Royer, Aurélien; Lécuyer, Christophe; Montuire, Sophie; Amiot, Romain; Legendre, Serge; Cuenca-Bescós, Gloria; Jeannet, Marcel; Martineau, François

    2013-01-01

    Oxygen isotope compositions of tooth phosphate (δ18Op) were measured in 107 samples defined on the basis of teeth obtained from 375 specimens of extant rodents. These rodents were sampled from pellets collected in Europe from 38°N (Portugal) to 65°N (Finland) with most samples coming from sites located in France and Spain. Large oxygen isotopic variability in δ18Op is observed both at the intra- and inter-species scale within pellets from a given location. This isotopic variability is partly explained by heterochrony in tooth formation related to the short time of mineralization for all rodent species as well as the duration of mineralization that is species-dependent. Consequently, tooth phosphate of rodents records a short seasonal interval in the oxygen isotope compositions of meteoric waters (δ18Omw). In addition, inter-species isotopic variability observed in the same pellets suggests behavioural differences implying distinct isotopic compositions for species living in the same location. At the scale of Europe, a robust linear oxygen isotope fractionation equation was determined for Muroidea between the midrange δ18Op values and δ18Omw values: δ18Op=1.21(±0.20)δ18Omw+24.76(±2.70) with R2=0.79 (n=9; p<0.0001).

  3. The ruthenium isotopic composition of the oceanic mantle

    Science.gov (United States)

    Bermingham, K. R.; Walker, R. J.

    2017-09-01

    The approximately chondritic relative, and comparatively high absolute mantle abundances of the highly siderophile elements (HSE), suggest that their concentrations in the bulk silicate Earth were primarily established during a final ∼0.5 to 1% of ;late accretion; to the mantle, following the cessation of core segregation. Consequently, the isotopic composition of the HSE Ru in the mantle reflects an amalgamation of the isotopic compositions of late accretionary contributions to the silicate portion of the Earth. Among cosmochemical materials, Ru is characterized by considerable mass-independent isotopic variability, making it a powerful genetic tracer of Earth's late accretionary building blocks. To define the Ru isotopic composition of the oceanic mantle, the largest portion of the accessible mantle, we report Ru isotopic data for materials from one Archean and seven Phanerozoic oceanic mantle domains. A sample from a continental lithospheric mantle domain is also examined. All samples have identical Ru isotopic compositions, within analytical uncertainties, indicating that Ru isotopes are well mixed in the oceanic mantle, defining a μ100Ru value of 1.2 ± 7.2 (2SD). The only known meteorites with the same Ru isotopic composition are enstatite chondrites and, when corrected for the effects of cosmic ray exposure, members of the Main Group and sLL subgroup of the IAB iron meteorite complex which have a collective CRE corrected μ100Ru value of 0.9 ± 3.0. This suggests that materials from the region(s) of the solar nebula sampled by these meteorites likely contributed the dominant portion of late accreted materials to Earth's mantle.

  4. Chemical composition, true metabolisable energy content and ...

    African Journals Online (AJOL)

    Chemical composition, true metabolisable energy content and amino acid availability of grain legumes for poultry. TS Brand, DA Brandt, CW Cruywagen. Abstract. South African Journal of Animal Science Vol.34(2) 2004: Samples of sweet yellow lupins (Lupinus luteus; n = 4), broad leaf lupins (Lupinus albus; n = 12), ...

  5. Estimating diets of pre-spawning Atlantic bluefin tuna from stomach content and stable isotope analyses

    Science.gov (United States)

    Varela, José L.; Rodríguez-Marín, Enrique; Medina, Antonio

    2013-02-01

    Stomach content analysis (SCA) and stable isotope analysis (SIA) coupled with isotopic mixing model analysis were used to estimate diet composition of pre-spawning Atlantic bluefin tuna (ABFT), Thunnus thynnus, caught by trap in the Strait of Gibraltar area. SCA provided poor information on diet as most of the stomachs appeared empty or contained only hard remains. Mixing model diet compositions estimated from muscle tissue SIA data did not show clear inter-annual variations and suggested that ABFT fed on prey that occupy high and intermediate level positions of the food web. Otherwise, diet compositions estimated from liver tissue SIA showed greater inter-annual variations and appeared to indicate that ABFT fed on prey located at lower trophic levels. The different dietary compositions inferred from muscle and liver samples were most probably due to the different turnover rates of these organs, which would provide trophic information at two distinct time scales. Our findings suggest that a combination of SCA and SIA is more suitable than using SCA alone to determine temporal and regional variations in ABFT diet composition.

  6. Effect of Ca content on equilibrium Ca isotope fractionation between orthopyroxene and clinopyroxene

    Science.gov (United States)

    Wang, Wenzhong; Zhou, Chen; Qin, Tian; Kang, Jin-Ting; Huang, Shichun; Wu, Zhongqing; Huang, Fang

    2017-12-01

    Concentration effect on equilibrium inter-mineral isotope fractionation is ubiquitous in solid solution systems, but it is not clear in which concentration range such effect is prominent. Using first-principles calculations, we examine the effect of Ca and Fe contents in orthopyroxene (opx) on its average Casbnd O bond length and the equilibrium Ca isotope fractionation factor (103lnα) between opx and clinopyroxene (cpx). Our results reveal that the average Casbnd O bond length in opx is much smaller than that in cpx and it does not change with variable Ca content x (x and y are mole ratios in CaxFeyMg1-x-ySiO3 thereafter here) when x ≤ 1/48. Incorporation of Fe (y ≥ 1/32) into opx with a fixed Ca content can only slightly increase the average Casbnd O bond length. 103lnαopx-cpx of 44Ca/40Ca is linearly correlated with the average Casbnd O bond length in opx, suggesting that 103lnαopx-cpx of 44Ca/40Ca is controlled by opx Casbnd O bond strength. Our calculations indicate that the Ca concentration effect on 103lnαopx-cpx is significant when x in opx ranges from 2/16 to 1/48, while Fe in natural opx only causes a slight decrease in 103lnαopx-cpx. Our results provide insights into Ca isotope fractionation in high-temperature geochemical processes. Given that Ca content x in opx from natural peridotites is usually lower than 1/32 and Fe content y is generally ∼10 mol%, Ca and Fe concentration effects on 103lnαopx-cpx in natural samples are negligible. Rather, 103lnαopx-cpx is mainly controlled by temperature. 103lnαopx-cpx of 44Ca/40Ca decreases from 0.50‰ to 0.26‰ when temperature increases from 1000 K to 1400 K if the Fe effect is taken into account. Therefore, if Ca isotope fractionation between opx and cpx (Δ44/40Caopx-cpx) in natural peridotites is greater than 0.50‰ or lower than 0.26‰, it may indicate disequilibrium of Ca isotopes. Finally, the large 103lnαopx-cpx relative to our current analytical precision suggests that Δ44/40Caopx

  7. Correspondence between human diet, body composition and stable isotopic composition of hair and breath in Fijian villagers.

    Science.gov (United States)

    Hedges, Robert; Rush, Elaine; Aalbersberg, William

    2009-03-01

    The main aim of this work was to describe the relationship between diet, and hair and breath isotopic composition. From one Fijian rural village, hair and breath samples were procured from 20 women. Physical anthropometrics were made, and hair (13)C/(12)C and (15)N/(14)N and breath (13)C/(12)C were measured. Individual diet diaries were kept for two of the four preceding weeks, and isotopic compositions of items which accounted for most of the diet were measured. Individual average diets were analysed for macronutrient and energy content and conform to reasonable nutritional expectation. Characteristics of the diet are described in terms of protein and energy, their patterning with respect to different clusters of food items and their relationship to individuals' anthropometry. Breath CO(2) is depleted in (13)C by 1-2 per thousand on average with respect to the total diet. Hair was enriched on average by 4.1 per thousand in nitrogen and 4.5 per thousand in carbon with respect to the total diet. There was insufficient population variation in hair isotopic composition to establish individual hair-diet isotopic differences. The definite relationship that we establish in this work, between dietary and tissue isotopic values for a human community, provides a basis for determining and validating dietary regimes more generally within non-industrial, non-global-'supermarket' economies.

  8. Characteristics of stable carbon isotopic composition of shale gas

    Directory of Open Access Journals (Sweden)

    Zhenya Qu

    2016-04-01

    Full Text Available A type Ⅱ kerogen with low thermal maturity was adopted to perform hydrocarbon generation pyrolysis experiments in a vacuum (Micro-Scale Sealed Vessel system at the heating rates of 2 °C/h and 20 °C/h. The stable carbon isotopic compositions of gas hydrocarbons were measured to investigate their evolving characteristics and the possible reasons for isotope reversal. The δ13C values of methane became more negative with the increasing pyrolysis temperatures until it reached the lightest point, after which they became more positive. Meanwhile, the δ13C values of ethane and propane showed a positive trend with elevating pyrolysis temperatures. The carbon isotopic compositions of shale gasses were mainly determined by the type of parent organic matter, thermal evolutionary extent, and gas migration in shale systems. Our experiments and study proved that the isotope reversal shouldn't occur in a pure thermogenic gas reservoir, it must be involved with some other geochemical process/es; although mechanisms responsible for the reversal are still vague. Carbon isotopic composition of the Fayetteville and Barnett shale gas demonstrated that the isotope reversal was likely involved with water–gas reaction and Fischer-Tropsch synthesis during its generation.

  9. Soil Carbon: Compositional and Isotopic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Moran, James J.; Alexander, M. L.; Laskin, Alexander

    2016-11-01

    This is a short chapter to be included in the next edition of the Encyclopedia of Soil Science. The work here describes techniques being developed at PNNL for investigating organic carbon in soils. Techniques discussed include: laser ablation isotope ratio mass spectrometry, laser ablation aerosol mass spectrometry, and nanospray desorption electrospray ionization mass spectrometry.

  10. Komatiites constrain molybdenum isotope composition of the Earth's mantle

    Science.gov (United States)

    Greber, Nicolas D.; Puchtel, Igor S.; Nägler, Thomas F.; Mezger, Klaus

    2015-07-01

    In order to estimate the Mo isotope composition and Mo abundance in the Bulk Silicate Earth (BSE), a total of thirty komatiite samples from five localities on three continents were analyzed using an isotope dilution double spike technique. Calculated Mo concentrations of the emplaced komatiite lavas range from 25 ± 3 to 66 ± 22 ng /g, and the inferred Mo concentrations in the deep mantle sources of the komatiites range between 17 ± 4 and 30 ± 12 ng /g, with an average value of 23 ± 7 ng /g (2SE). This average value represents our best estimate for the Mo concentration in the BSE; it is identical, within the uncertainty, to published previous estimates of 39 ± 16 ng /g, but is at least a factor of 2 more precise. The Mo isotope compositions of the komatiite mantle sources overlap within uncertainty and range from δ98Mo = - 0.04 ± 0.28 to 0.11 ± 0.10 ‰, with an average of 0.04 ± 0.06 ‰ (2SE). This value is analytically indistinguishable from published Mo isotope compositions of ordinary and enstatite chondrites and represents the best estimate for the Mo isotope composition of the BSE. The inferred δ98Mo for the BSE is therefore lighter than the suggested average of the upper continental crust (0.3 to 0.4‰). Thus, from the mass balance standpoint, a reservoir with lighter Mo isotope composition should exist in the Earth's mantle; this reservoir can potentially be found in subducted oceanic crust. The similarity of δ98Mo between chondritic meteorites and estimates for the BSE from this study indicates that during the last major equilibration between Earth's core and mantle, i.e., the one that occurred during the giant impact that produced the Moon, chemical and isotopic equilibrium of Mo between Fe metal of the core and the silicate mantle was largely achieved.

  11. Aerosol carbon isotope composition over Baltic Sea

    Science.gov (United States)

    Garbaras, Andrius; Pabedinskas, Algirdas; Masalaite, Agne; Petelski, Tomasz; Gorokhova, Elena; Sapolaite, Justina; Ezerinskis, Zilvinas; Remeikis, Vidmantas

    2017-04-01

    Particulate carbonaceous matter is significant contributor to ambient particulate matter originating from intervening sources which contribution is difficult to quantify due to source diversity, chemical complexity and processes during atmospheric transport. Carbon isotope analysis can be extremely useful in source apportionment of organic matter due to the unique isotopic signatures associated with anthropocentric (fossil fuel), continental (terrestrial plants) and marine sources, and is particularly effective when these sources are mixed (Ceburnis et al., 2011;Ceburnis et al., 2016). We will present the isotope ratio measurement results of aerosol collected during the cruise in the Baltic Sea. Sampling campaign of PM10 and size segregated aerosol particles was performed on the R/V "Oceania" in October 2015. Air mass back trajectories were prevailing both from the continental and marine areas during the sampling period. The total carbon concentration varied from 1 µg/m3 to 8 µg/m3. Two end members (δ13C = -25‰ and δ13C = -28 ‰ ) were established from the total stable carbon isotope analysis in PM10 fraction. δ13C analysis in size segregated aerosol particles revealed δ13C values being highest in the 1 - 2.5 µm range (δ13C = -24.9 ‰ ) during continental transport, while lowest TC δ13C values (δ13C ≈ -27 ‰ ) were detected in the size range D50 marine environment. Additionally, concentration of bacteria and fungi were measured in size segregated and PM10 aerosol fraction. We were able to relate aerosol source δ13C end members with the abundance of bacteria and fungi over Baltic Sea combining air mass trajectories, stable isotope data, fungi and bacteria concentrations. Ceburnis, D., Garbaras, A., Szidat, S., Rinaldi, M., Fahrni, S., Perron, N., Wacker, L., Leinert, S., Remeikis, V., and Facchini, M.: Quantification of the carbonaceous matter origin in submicron marine aerosol by 13 C and 14 C isotope analysis, Atmospheric Chemistry and Physics

  12. Magnesium isotope evidence that accretional vapour loss shapes planetary compositions

    Science.gov (United States)

    Hin, Remco C.; Coath, Christopher D.; Carter, Philip J.; Nimmo, Francis; Lai, Yi-Jen; Pogge von Strandmann, Philip A. E.; Willbold, Matthias; Leinhardt, Zoë M.; Walter, Michael J.; Elliott, Tim

    2017-09-01

    It has long been recognized that Earth and other differentiated planetary bodies are chemically fractionated compared to primitive, chondritic meteorites and, by inference, the primordial disk from which they formed. However, it is not known whether the notable volatile depletions of planetary bodies are a consequence of accretion or inherited from prior nebular fractionation. The isotopic compositions of the main constituents of planetary bodies can contribute to this debate. Here we develop an analytical approach that corrects a major cause of measurement inaccuracy inherent in conventional methods, and show that all differentiated bodies have isotopically heavier magnesium compositions than chondritic meteorites. We argue that possible magnesium isotope fractionation during condensation of the solar nebula, core formation and silicate differentiation cannot explain these observations. However, isotopic fractionation between liquid and vapour, followed by vapour escape during accretionary growth of planetesimals, generates appropriate residual compositions. Our modelling implies that the isotopic compositions of magnesium, silicon and iron, and the relative abundances of the major elements of Earth and other planetary bodies, are a natural consequence of substantial (about 40 per cent by mass) vapour loss from growing planetesimals by this mechanism.

  13. Magnesium isotope evidence that accretional vapour loss shapes planetary compositions.

    Science.gov (United States)

    Hin, Remco C; Coath, Christopher D; Carter, Philip J; Nimmo, Francis; Lai, Yi-Jen; Pogge von Strandmann, Philip A E; Willbold, Matthias; Leinhardt, Zoë M; Walter, Michael J; Elliott, Tim

    2017-09-27

    It has long been recognized that Earth and other differentiated planetary bodies are chemically fractionated compared to primitive, chondritic meteorites and, by inference, the primordial disk from which they formed. However, it is not known whether the notable volatile depletions of planetary bodies are a consequence of accretion or inherited from prior nebular fractionation. The isotopic compositions of the main constituents of planetary bodies can contribute to this debate. Here we develop an analytical approach that corrects a major cause of measurement inaccuracy inherent in conventional methods, and show that all differentiated bodies have isotopically heavier magnesium compositions than chondritic meteorites. We argue that possible magnesium isotope fractionation during condensation of the solar nebula, core formation and silicate differentiation cannot explain these observations. However, isotopic fractionation between liquid and vapour, followed by vapour escape during accretionary growth of planetesimals, generates appropriate residual compositions. Our modelling implies that the isotopic compositions of magnesium, silicon and iron, and the relative abundances of the major elements of Earth and other planetary bodies, are a natural consequence of substantial (about 40 per cent by mass) vapour loss from growing planetesimals by this mechanism.

  14. Stable isotope composition of human fingernails from Slovakia

    Energy Technology Data Exchange (ETDEWEB)

    Grolmusová, Zuzana, E-mail: zuzana.grolmusova@geology.sk [Comenius University in Bratislava, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F2, 842 48 Bratislava (Slovakia); State Geological Institute of Dionýz Štúr, Laboratory of Isotope Geology, Mlynská dolina 1, 817 04 Bratislava (Slovakia); Rapčanová, Anna [Comenius University in Bratislava, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F2, 842 48 Bratislava (Slovakia); Michalko, Juraj; Čech, Peter [State Geological Institute of Dionýz Štúr, Laboratory of Isotope Geology, Mlynská dolina 1, 817 04 Bratislava (Slovakia); Veis, Pavel [Comenius University in Bratislava, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F2, 842 48 Bratislava (Slovakia); State Geological Institute of Dionýz Štúr, Laboratory of Isotope Geology, Mlynská dolina 1, 817 04 Bratislava (Slovakia)

    2014-10-15

    Stable isotope composition of human fingernails has proven to be useful for documenting human dietary information and geographical patterns in archeological, forensic, anthropological and biological studies. Therefore, it is of interest to detect all factors influencing the stable isotopic composition in the certain regions in the world. Carbon and nitrogen isotope data of human fingernail keratin from 52 individuals from Slovakia were reported in this study. The online combustion and continuous flow isotope-ratio mass spectrometer Delta V Advantage was used for δ{sup 13}C and δ{sup 15}N analysis of fingernail keratin samples from 24 vegetarian and 28 omnivorous individuals. A group of people with frequent meat consumption showed enrichment in {sup 13}C and {sup 15}N isotopes in fingernails. A similar trend was observed with increasing seafood in an individual's diet. Moreover a significant difference was revealed between smokers and nonsmokers for both δ{sup 13}C and δ{sup 15}N values. These data were compared to previously published δ{sup 13}C and δ{sup 15}N fingernail values from across the globe. This study brings new information on the stable isotope signature of individuals from Slovakia and characterizes the Central European region for the first time. The stable isotope composition of fingernails is influenced by the frequency of meat and seafood consumption as well as smoking. - Highlights: • This study deals with stable isotope analyses of fingernails from Slovak volunteers. • δ{sup 13}C and δ{sup 15}N values of vegetarian and omnivore fingernails were compared. • Influence of sex, diet and smoking was studied.

  15. Stable isotope composition of human fingernails from Slovakia

    International Nuclear Information System (INIS)

    Grolmusová, Zuzana; Rapčanová, Anna; Michalko, Juraj; Čech, Peter; Veis, Pavel

    2014-01-01

    Stable isotope composition of human fingernails has proven to be useful for documenting human dietary information and geographical patterns in archeological, forensic, anthropological and biological studies. Therefore, it is of interest to detect all factors influencing the stable isotopic composition in the certain regions in the world. Carbon and nitrogen isotope data of human fingernail keratin from 52 individuals from Slovakia were reported in this study. The online combustion and continuous flow isotope-ratio mass spectrometer Delta V Advantage was used for δ 13 C and δ 15 N analysis of fingernail keratin samples from 24 vegetarian and 28 omnivorous individuals. A group of people with frequent meat consumption showed enrichment in 13 C and 15 N isotopes in fingernails. A similar trend was observed with increasing seafood in an individual's diet. Moreover a significant difference was revealed between smokers and nonsmokers for both δ 13 C and δ 15 N values. These data were compared to previously published δ 13 C and δ 15 N fingernail values from across the globe. This study brings new information on the stable isotope signature of individuals from Slovakia and characterizes the Central European region for the first time. The stable isotope composition of fingernails is influenced by the frequency of meat and seafood consumption as well as smoking. - Highlights: • This study deals with stable isotope analyses of fingernails from Slovak volunteers. • δ 13 C and δ 15 N values of vegetarian and omnivore fingernails were compared. • Influence of sex, diet and smoking was studied

  16. Chemical and isotopic compositions in acid residues from various meteorites

    Science.gov (United States)

    Kano, N.; Yamakoshi, K.; Matsuzaki, H.; Nogami, K.

    1993-03-01

    We are planning to carry out systematic isotopic investigations of Ru, Mg, etc., in primordial samples. The investigations will be pursued in the context of a study of the pre-history of the solar system. It is hoped that the study will yield direct evidence for processes of nucleosynthesis in the pre-solar stage and detection of extinct radioactive nuclides. In this paper, we present the results of chemical compositions of acid residues obtained from three types of meteorites: Canyon Diablo (IA), Allende (CV3), and Nuevo Mercuro (H5); and the preliminary results of Ru isotopic compositions.

  17. Anomalous isotopic composition of cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Woosley, S.E.; Weaver, T.A.

    1980-06-20

    Recent measurements of nonsolar isotopic patterns for the elements neon and (perhaps) magnesium in cosmic rays are interpreted within current models of stellar nucleosynthesis. One possible explanation is that the stars currently responsible for cosmic-ray synthesis in the Galaxy are typically super-metal-rich by a factor of two to three. Other possibilities include the selective acceleration of certain zones or masses of supernovas or the enhancement of /sup 22/Ne in the interstellar medium by mass loss from red giant stars and planetary nebulas. Measurements of critical isotopic ratios are suggested to aid in distinguishing among the various possibilities. Some of these explanations place significant constraints on the fraction of cosmic ray nuclei that must be fresh supernova debris and the masses of the supernovas involved. 1 figure, 3 tables.

  18. Thallium isotope composition of the upper continental crust and rivers - An investigation of the continental sources of dissolved marine thallium

    Science.gov (United States)

    Nielsen, S.G.; Rehkamper, M.; Porcelli, D.; Andersson, P.; Halliday, A.N.; Swarzenski, P.W.; Latkoczy, C.; Gunther, D.

    2005-01-01

    The thallium (Tl) concentrations and isotope compositions of various river and estuarine waters, suspended riverine particulates and loess have been determined. These data are used to evaluate whether weathering reactions are associated with significant Tl isotope fractionation and to estimate the average Tl isotope composition of the upper continental crust as well as the mean Tl concentration and isotope composition of river water. Such parameters provide key constraints on the dissolved Tl fluxes to the oceans from rivers and mineral aerosols. The Tl isotope data for loess and suspended riverine detritus are relatively uniform with a mean of ??205Tl = -2.0 ?? 0.3 (??205Tl represents the deviation of the 205Tl/203Tl isotope ratio of a sample from NIST SRM 997 Tl in parts per 104). For waters from four major and eight smaller rivers, the majority were found to have Tl concentrations between 1 and 7 ng/kg. Most have Tl isotope compositions very similar (within ??1.5 ??205Tl) to that deduced for the upper continental crust, which indicates that no significant Tl isotope fractionation occurs during weathering. Based on these results, it is estimated that rivers have a mean natural Tl concentration and isotope composition of 6 ?? 4 ng/kg and ??205Tl = -2.5 ?? 1.0, respectively. In the Amazon estuary, both additions and losses of Tl were observed, and these correlate with variations in Fe and Mn contents. The changes in Tl concentrations have much lower amplitudes, however, and are not associated with significant Tl isotope effects. In the Kalix estuary, the Tl concentrations and isotope compositions can be explained by two-component mixing between river water and a high-salinity end member that is enriched in Tl relative to seawater. These results indicate that Tl can display variable behavior in estuarine systems but large additions and losses of Tl were not observed in the present study. Copyright ?? 2005 Elsevier Ltd.

  19. Oxygen Isotopic Compositions of Olivine and Pyroxene from CI Chondrites

    Science.gov (United States)

    Leshin, L. A.; Rubin, A. E.; McKeegan, K. D.

    1996-03-01

    The oxygen isotopic compositions of carbonaceous chondrites are complicated since individual components of these meteorites have distinct isotopic compositions that have been affected, to varying degrees, by both nebular and parent body processes. We present the first measurements of oxygen isotopic compositions of rare olivine and pyroxene in the CI chondrites. By combining these data with oxygen isotopic analyses of secondary minerals in these rocks previously reported by Clayton and co-workers, we hope to place quantitative constraints on the physical processes that occurred during formation of these meteorites. The oxygen isotopic composition of separated olivine and pyroxene grains from Orgueil and Ivuna were measured using SIMS. The delta ^(18)O values of the olivines range from ~+3 to +13 and the delta^(17)O values range from ~+1 to +7. The delta^(18)O values of the pyroxenes range from ~+4 to +10 and the delta^(17)O values range from ~+2 to +5. Observations that will be explained in the interpretation of the data are: (1) CI pyroxene and olivine grains have essentially identical oxygen isotopic compositions which are distinct from those measured in other carbonaceous chondrites. (2) All data points except two are indistinguishable from terrestrial values at the one sigma level, and the two exceptions fall only slightly below the terrestrial fractionation line. We consider the data taken as a whole to be consistent with terrestrial values, as well as the slightly positive delta^(17)O values reported previously for matrix and magnetite in CI chondrites. (3) Due to the small range in d values observed relative to the uncertainties, it is not possible to distinguish whether these data fall on a line of approximately slope 1 or slope 1/2.

  20. What controls the isotopic composition of Greenland surface snow?

    Directory of Open Access Journals (Sweden)

    H. C. Steen-Larsen

    2014-02-01

    Full Text Available Water stable isotopes in Greenland ice core data provide key paleoclimatic information, and have been compared with precipitation isotopic composition simulated by isotopically enabled atmospheric models. However, post-depositional processes linked with snow metamorphism remain poorly documented. For this purpose, monitoring of the isotopic composition (δ18O, δD of near-surface water vapor, precipitation and samples of the top (0.5 cm snow surface has been conducted during two summers (2011–2012 at NEEM, NW Greenland. The samples also include a subset of 17O-excess measurements over 4 days, and the measurements span the 2012 Greenland heat wave. Our observations are consistent with calculations assuming isotopic equilibrium between surface snow and water vapor. We observe a strong correlation between near-surface vapor δ18O and air temperature (0.85 ± 0.11‰ °C−1 (R = 0.76 for 2012. The correlation with air temperature is not observed in precipitation data or surface snow data. Deuterium excess (d-excess is strongly anti-correlated with δ18O with a stronger slope for vapor than for precipitation and snow surface data. During nine 1–5-day periods between precipitation events, our data demonstrate parallel changes of δ18O and d-excess in surface snow and near-surface vapor. The changes in δ18O of the vapor are similar or larger than those of the snow δ18O. It is estimated using the CROCUS snow model that 6 to 20% of the surface snow mass is exchanged with the atmosphere. In our data, the sign of surface snow isotopic changes is not related to the sign or magnitude of sublimation or deposition. Comparisons with atmospheric models show that day-to-day variations in near-surface vapor isotopic composition are driven by synoptic variations and changes in air mass trajectories and distillation histories. We suggest that, in between precipitation events, changes in the surface snow isotopic composition are driven by these changes in near

  1. Carbon fiber content measurement in composite

    Science.gov (United States)

    Wang, Qiushi

    Carbon fiber reinforced polymers (CFRPs) have been widely used in various structural applications in industries such as aerospace and automotive because of their high specific stiffness and specific strength. Their mechanical properties are strongly influenced by the carbon fiber content in the composites. Measurement of the carbon fiber content in CFRPs is essential for product quality control and process optimization. In this work, a novel carbonization-in-nitrogen method (CIN) is developed to characterize the fiber content in carbon fiber reinforced thermoset and thermoplastic composites. In this method, a carbon fiber composite sample is carbonized in a nitrogen environment at elevated temperatures, alongside a neat resin sample. The carbon fibers are protected from oxidization while the resin (the neat resin and the resin matrix in the composite sample) is carbonized under the nitrogen environment. The residue of the carbonized neat resin sample is used to calibrate the resin carbonization rate and calculate the amount of the resin matrix in the composite sample. The new method has been validated on several thermoset and thermoplastic resin systems and found to yield an accurate measurement of fiber content in carbon fiber polymer composites. In order to further understand the thermal degradation behavior of the high temperature thermoplastic polymer during the carbonization process, the mechanism and the kinetic model of thermal degradation behavior of carbon fiber reinforced poly (phenylene sulfide) (CPPS) are studied using thermogravimetry analysis (TGA). The CPPS is subjected to TGA in an air and nitrogen atmosphere at heating rates from 5 to 40°C min--1. The TGA curves obtained in air are different from those in nitrogen. This demonstrates that weight loss occurs in a single stage in nitrogen but in two stages in air. To elucidate this difference, thermal decomposition kinetics is analyzed by applying the Kissinger, Flynn-Wall-Ozawa, Coat-Redfern and

  2. Measurement of Plutonium Isotopic Composition - MGA

    Energy Technology Data Exchange (ETDEWEB)

    Vo, Duc Ta [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-21

    In this module, we will use the Canberra InSpector-2000 Multichannel Analyzer with a high-purity germanium detector (HPGe) and the MGA isotopic anlysis software to assay a variety of plutonium samples. The module provides an understanding of the MGA method, its attributes and limitations. You will assess the system performance by measuring a range of materials similar to those you may assay in your work. During the final verification exercise, the results from MGA will be combined with the 240Pueff results from neutron coincidence or multiplicity counters so that measurements of the plutonium mass can be compared with the operator-declared (certified) values.

  3. H-Isotopic Composition of Apatite in Northwest Africa 7034

    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 estimates of Mars' bulk crust composition [1]. Given the similarities between NWA 7034 and the martian crust, NWA 7034 may represent an important sample for constraining the crustal composition of components that cannot be measured directly by remote sensing. In the present study, we seek to constrain the H isotopic composition of the martian crust using Cl-rich apatite in NWA 7034.

  4. Oxygen isotopic constraints on the composition of the moon

    Science.gov (United States)

    Grossman, L.; Clayton, R. N.; Mayeda, T. K.

    1974-01-01

    The mean oxygen isotopic composition of 5 Apollo 17 soils, one Apollo 17 breccia and one Apollo 12 soil is delta O-18 = 5.63 + or - .05 and delta O-17 = 3.8 + or - .2%. These values are within several tenths of a part permil of the composition of a large fraction of the lunar interior. High-temperature condensate aggregates from Allende and other C2 and C3 chondrites are vastly enriched in O-16 compared to this composition. The moon cannot be a mixture of ordinary chondrites and Allende inclusions, nor can it be derived from such a mixture by chemical fractionation processes. The moon's isotopic composition is consistent with a mixture of high- and low-temperature condensates but the refractory fraction would have to be free of the O-16-rich component so prevalent in the meteoritic aggregates, a fact which makes such models less attractive than they once seemed.

  5. Method-Dependent Variations in Oxygen Isotope Compositions Obtained for Structural Carbonate in Bone Bioapatite

    Science.gov (United States)

    Metcalfe, J. Z.; Longstaffe, F. J.; White, C. D.

    2007-12-01

    The carbon and oxygen isotope compositions of structural carbonate contained in bioapatite can be obtained by reaction with ortho-phosphoric acid at various temperatures and reaction times, using off-line or automated sample preparation, and continuous-flow or dual-inlet isotope-ratio mass spectrometry (IRMS). Here, we compare the isotopic compositions obtained for structural carbonate in bone bioapatite using (1) conventional off- line gas extraction (25°C) and dual-inlet IRMS, (2) GasBench automated sampling (50°C) and continuous-flow IRMS, and (3) MultiPrep automated sampling (50°C, 90°C) and dual-inlet IRMS. On average, the stable carbon isotope compositions obtained for the same sample using different methods are within ±0.33 per mil (n=29). The reproducibility of oxygen isotope compositions using the different methods is much poorer (±3.18 per mil; n=29). The differences among these methods were most pronounced for samples analyzed using the MultiPrep at 90°C and dual-inlet IRMS. In the latter case, some samples consistently had extremely low oxygen isotope compositions, and also yielded a contaminant gas containing masses 47, 48, and 49, which was not separated from the normal reaction product (carbon dioxide) during cryogenic processing. Normal and anomalous samples do not systematically differ in their crystallinity indices, C/P ratios, gas yields, or total organic content. Anomalous samples have an additional peak in their deconvoluted FTIR spectra at 866 cm-1 and their ignition products lack β-TCP. They also contain slightly more Al and Si cations, and slightly fewer Na cations. It is not clear how these subtle structural and chemical differences relate to the production of the contaminant gas.

  6. Transition of the Isotopic Composition of Leaf Water to the Isotopic Steady State in Soybean and Corn

    Science.gov (United States)

    Kim, K.; Lee, X.; Welp, L. R.

    2007-12-01

    The isotope composition of leaf water (δL) plays an important role in the isotopic water and carbon fluxes between terrestrial plants and the atmosphere. The objective of this study is to improve our understanding of environmental and biological controls on the transition of δL to steady state through laboratory experiments. Plants (soybean, Glycine max; corn, Zea mays) were grown hydroponically with water of a known isotopic content in a greenhouse. On the day of the experiment, they were first moved to ambient environment in full sunlight for at least 6 hr and then into a dark container inside the lab for up to 48 hr in which water vapor isotope ratios, temperature, and humidity were controlled. This arrangement created a step change in the forcing on the plant isotopic exchange. Leaves were sampled prior to the transfer to the dark container and 6 more times every 4 - 12 hr over the experiment. In the first set of experiments, humidity inside the container was saturated to mimic dew events in field conditions. In the second set, humidity was controlled at approximately 95%. Water from the leaf samples was extracted by a vacuum line and was analyzed for both δD and δ18O. The dataset will allow us to evaluate leaf water isotopic theories by exploring the transitions of δL in response to the step change. Specifically, we are interested in whether the stomatal opening is an effective pathway for gaseous exchange in total darkness and how the transitional behaviors of δL differ between the C3 and C4 photosynthesis pathways.

  7. elemental and isotopic compositions of organic carbon and nitrogen ...

    African Journals Online (AJOL)

    Muzuka – Elements and isotopic composition of organic carbon and nitrogen … 88. (2000), the East African region experienced drought during Medieval warm period and humid conditions during little ice age. Further south in South Africa, Holmgren et al. (2001) using record of stalagmite from. Cold air cave in the ...

  8. Determination of hydrogen isotope composition in organic compounds

    International Nuclear Information System (INIS)

    Ordzhonikidze, K.G.; Parulava, L.P.; Vakhaniya, G.V.; Tarielashvili, V.O.

    1989-01-01

    method for determination of hydrogen isotope composition just in organic compounds using mass-spectrometer of the second class is suggested. The method enables to determine atomic fraction of hydrogen without multiplet separation. The accuracy of determination of deuterium atomic fraction in acetone in 1-99% range was equal to 3-0.2% respectively

  9. Carbon isotopic composition of fossil leaves from the Early ...

    Indian Academy of Sciences (India)

    carbon isotopic composition. The study of fossil plant or plant mega fossil has certain advantages over the use of bulk terrestrial organic matter. (TOM) that is widely used to establish correlation between the marine and terrestrial carbon cycle events through geological time (Grocke et al 2005). For example, the TOM can be ...

  10. Elemental and isotopic compositions of organic carbon and nitrogen ...

    African Journals Online (AJOL)

    Elemental and isotopic compositions of organic carbon and nitrogen of recently deposited organic matter in Empakai crater and its implication for climatic changes ... The C/N ratios values, which average 12.2±2.3, increase downcore to the base of the core owing to preferential loss of nitrogen containing compounds during ...

  11. Carbon and oxygen isotopic compositions and diagenesis of the ...

    African Journals Online (AJOL)

    Carbon and oxygen isotopic compositions and diagenesis of the Ewekoro formation in the eastern Dahomey Basin, southwestern Nigeria. OA Adekeye, SO Akande, RB Bale, BD Erdtmann. Abstract. No Abstract. Journal of Mining and Geology 2005, Vol. 41(1): 87-95. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT

  12. Facies, dissolution seams and stable isotope compositions of the ...

    Indian Academy of Sciences (India)

    Stable isotope analysis of the limestone shows that 13C and 18O values are compatible with the early Mesoproterozoic open seawater composition. The ribbon limestone facies in the Rohtas Limestone is characterized by micritic beds, each decoupled in a lower band enriched and an upper band depleted in dissolution ...

  13. The Pre-History of Chondrules Based on Initial Pb Isotopic Compositions

    Science.gov (United States)

    Connelly, J. N.; Bizzarro, M.

    2012-09-01

    We use the initial Pb isotopic composition of Pb-Pb dated chondrules to explore the initial Pb isotopic composition of the solar system and the thermal histories of chondrules prior to their final closure.

  14. 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

  15. Elemental and iron isotopic composition of aerosols collected in a parking structure

    Energy Technology Data Exchange (ETDEWEB)

    Majestic, Brian J., E-mail: brian.majestic@asu.edu [Department of Chemistry and Biochemistry, Arizona State University, PO Box 871604, Tempe, AZ 85287-1604 (United States); Anbar, Ariel D. [Department of Chemistry and Biochemistry, Arizona State University, PO Box 871604, Tempe, AZ 85287-1604 (United States); School of Earth and Space Exploration, Arizona State University, PO Box 871604, Tempe, AZ 85287-1604 (United States); Herckes, Pierre [Department of Chemistry and Biochemistry, Arizona State University, PO Box 871604, Tempe, AZ 85287-1604 (United States)

    2009-09-01

    The trace metal contents and iron isotope composition of size-resolved aerosols were determined in a parking structure in Tempe, AZ, USA. Particulate matter (PM) < 2.5 {mu}m in diameter (the fine fraction) and PM > 2.5 {mu}m were collected. Several air toxics (e.g., arsenic, cadmium, and antimony) were enriched above the crustal average, implicating automobiles as an important source. Extremely high levels of fine copper (up to 1000 ng m{sup -3}) were also observed in the parking garage, likely from brake wear. The iron isotope composition of the aerosols were found to be + 0.15 {+-} 0.03 per mille and + 0.18 {+-} 0.03 per mille for the PM < 2.5 {mu}m and PM > 2.5 {mu}m fractions, respectively. The similarity of isotope composition indicates a common source for each size fraction. To better understand the source of iron in the parking garage, the elemental composition in four brake pads (two semi-metallic and two ceramic), two tire tread samples, and two waste oil samples were determined. Striking differences in the metallic and ceramic brake pads were observed. The ceramic brake pads contained 10-20% copper by mass, while the metallic brake pads contained about 70% iron, with very little copper. Both waste oil samples contained significant amounts of calcium, phosphorous, and zinc, consistent with the composition of some engine oil additives. Differences in iron isotope composition were observed between the source materials; most notably between the tire tread (average = + 0.02 per mille ) and the ceramic brake linings (average = + 0.65 per mille ). Differences in isotopic composition were also observed between the metallic (average = + 0.18 per mille ) and ceramic brake pads, implying that iron isotope composition may be used to resolve these sources. The iron isotope composition of the metallic brake pads was found to be identical to the aerosols, implying that brake dust is the dominant source of iron in a parking garage.

  16. Isotopic composition of lead ore from the Japanese islands

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Akira (Geological Survey of Japan, Yatabe, Ibaraki (Japan)); Sato, Kazuo; Cumming, G.L.

    1982-12-01

    The metallic mineralization in Japanese islands can be divided into three groups in view of the ore lead isotope systematics. The Paleozoic to Mesozoic stratiform (Besshi type) mineralization is composed of cupriferous iron sulfide ore, in which lead is usually a minor constituent. The lead is isotopically variable, being consistently low in both Pb-207/Pb-204 and Pb-208/Pb-204 ratios. The pre-Neogene mineralization excluding the Besshi type deposit is mostly related to Cretaceous to Paleogene granitoids. Galena is fairly common, and forms sizable ore bodies in a few skarn type deposits. The isotopic composition of lead is variable regionally, low in Pb-206/Pb-204 but high in Pb-208/Pb-204 in all cases. The Neogene mineralization is represented by kuroko mineralization and the related vein type one of middle Miocene age, carrying abundant lead as one of the major ore metals. The lead is isotopically rather uniform with consistently low Pb-206/Pb-204 and high Pb-208/Pb-204. Forty-three samples from 30 localities gave the average Pb-206/Pb-204, Pb-207/Pb-204 and Pb-208/Pb-204 ratios of 18.471 +- 0.108, 15.609 +- 0.036 and 38.677 +- 0.0220, respectively. A remarkably consistent isotopic composition close to this average was observed in the kuroko ore from north-east Japan. The crustal lead around Japanese islands has been strongly influenced by the lead evolved in the lower continental crust.

  17. Menopause effect on blood Fe and Cu isotope compositions.

    Science.gov (United States)

    Jaouen, Klervia; Balter, Vincent

    2014-02-01

    Iron (δ(56) Fe) and copper (δ(65) Cu) stable isotope compositions in blood of adult human include a sex effect, which still awaits a biological explanation. Here, we investigate the effect of menopause by measuring blood δ(56) Fe and δ(65) Cu values of aging men and women. The results show that, while the Fe and Cu isotope compositions of blood of men are steady throughout their lifetime, postmenopausal women exhibit blood δ(65) Cu values similar to men, and δ(56) Fe values intermediate between men and premenopausal women. The residence time of Cu and Fe in the body likely explains why the blood δ(65) Cu values, but not the δ(56) Fe values, of postmenopausal women resemble that of men. We suggest that the Cu and Fe isotopic fractionation between blood and liver resides in the redox reaction occurring during hepatic solicitation of Fe stores. This reaction affects the Cu speciation, which explains why blood Cu isotope composition is impacted by the cessation of menstruations. Considering that Fe and Cu sex differences are recorded in bones, we believe this work has important implications for their use as a proxy of sex or age at menopause in past populations. Copyright © 2013 Wiley Periodicals, Inc.

  18. Variable Isotopic Compositions of Host Plant Populations Preclude Assessment of Aphid Overwintering Sites

    Directory of Open Access Journals (Sweden)

    Michael S. Crossley

    2017-12-01

    Full Text Available Soybean aphid (Aphis glycines Matsumura is a pest of soybean in the northern Midwest whose migratory patterns have been difficult to quantify. Improved knowledge of soybean aphid overwintering sites could facilitate the development of control efforts with exponential impacts on aphid densities on a regional scale. In this preliminary study, we explored the utility of variation in stable isotopes of carbon and nitrogen to distinguish soybean aphid overwintering origins. We compared variation in bulk 13C and 15N content in buckthorn (Rhamnus cathartica L. and soybean aphids in Wisconsin, among known overwintering locations in the northern Midwest. Specifically, we looked for associations between buckthorn and environmental variables that could aid in identifying overwintering habitats. We detected significant evidence of correlation between the bulk 13C and 15N signals of soybean aphids and buckthorn, despite high variability in stable isotope composition within and among buckthorn plants. Further, the 15N signal in buckthorn varied predictably with soil composition. However, lack of sufficient differentiation of geographic areas along axes of isotopic and environmental variation appears to preclude the use of carbon and nitrogen isotopic signals as effective predictors of likely aphid overwintering sites. These preliminary data suggest the need for future work that can further account for variability in 13C and 15N within/among buckthorn plants, and that explores the utility of other stable isotopes in assessing likely aphid overwintering sites.

  19. Monitoring of chemical and isotopic composition of the Euphrates river in Syria

    International Nuclear Information System (INIS)

    Kattan, Z.

    2008-11-01

    The ratios of stable isotopes ( 18 O and 2 H), tritium content, together with the chemical composition of major ions of the Euphrates and Balikh (Euphrates tributary) Rivers, and the groundwaters of four wells drilled close to the Euphrates River course, were measured on a monthly basis. The Euphrates River water was monitored at twelve stations along its course in Syria during the period from January 2004 to December 2006, whereas those of the Balikh and groundwaters were only investigated during 2005. Although, the spatial variations of heavy stable isotope concentrations are moderated with respect to other large rivers in the world, the concentrations of these isotopes increase generally downstream the Euphrates River, with a sharp enrichment at Al-Assad Lake. This sharp increase could be explained by the effect of direct evaporation from the river and its tributaries; and the effect of drainage return flows of irrigation waters, isotopically more enriched. Enrichment of stable isotopes in the Euphrates River water was used as a direct indicator of evaporation. Based on an experimental evaporation result of a Euphrates water sample and the integral enrichment of heavy stable isotopes in the Euphrates River system, the amount of water losses by evaporation from Al-Assad Lake was estimated to be about 1.26 to 1.62 billion m''3, according to 18 O and deuterium ( 2 H), respectively. This amount represents about 12-16% of the renewable surface water resources in the country. (author)

  20. The chlorine isotope composition of the moon and implications for an anhydrous mantle.

    Science.gov (United States)

    Sharp, Z D; Shearer, C K; McKeegan, K D; Barnes, J D; Wang, Y Q

    2010-08-27

    Arguably, the most striking geochemical distinction between Earth and the Moon has been the virtual lack of water (hydrogen) in the latter. This conclusion was recently challenged on the basis of geochemical data from lunar materials that suggest that the Moon's water content might be far higher than previously believed. We measured the chlorine isotope composition of Apollo basalts and glasses and found that the range of isotopic values [from -1 to +24 per mil (per thousand) versus standard mean ocean chloride] is 25 times the range for Earth. The huge isotopic spread is explained by volatilization of metal halides during basalt eruption--a process that could only occur if the Moon had hydrogen concentrations lower than those of Earth by a factor of approximately 10(4) to 10(5), implying that the lunar interior is essentially anhydrous.

  1. Stable isotope composition and volume of Early Archaean oceans

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Rosing, Minik Thorleif; Bird, Dennis K.

    Oxygen and hydrogen isotope compositions of seawater are controlled by volatile fluxes between mantle, lithospheric (oceanic and continental crust) and atmospheric reservoirs. Throughout geologic time oxygen was likely conserved within these Earth system reservoirs, but hydrogen was not, as it can...... escape to space [1]. Hydrogen isotope ratios of serpentinites from the ~3.8Ga Isua Supracrustal Belt in West Greenland are between -53 and -99‰; the highest values are in antigorite ± lizardite serpentinites from a low-strain lithologic domain where hydrothermal reaction of Archaean seawater with oceanic...... of continents present at that time), and the mass of Early Archaean oceans to ~109 to 126% of present day oceans. Oxygen isotope analyses from these Isua serpentinites (δ18O = +0.1 to 5.6‰ relative to VSMOW) indicate that early Archaean δ18OSEAWATER similar to modern oceans. Our observations suggest...

  2. High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry.

    Science.gov (United States)

    Paul, Maxence; Bridgestock, Luke; Rehkämper, Mark; van DeFlierdt, Tina; Weiss, Dominik

    2015-03-10

    A new method for the determination of seawater Pb isotope compositions and concentrations was developed, which combines and optimizes previously published protocols for the separation and isotopic analysis of this element. For isotopic analysis, the procedure involves initial separation of Pb from 1 to 2L of seawater by co-precipitation with Mg hydroxide and further purification by a two stage anion exchange procedure. The Pb isotope measurements are subsequently carried out by thermal ionization mass spectrometry using a (207)Pb-(204)Pb double spike for correction of instrumental mass fractionation. These methods are associated with a total procedural Pb blank of 28±21 pg (1sd) and typical Pb recoveries of 40-60%. The Pb concentrations are determined by isotope dilution (ID) on 50 mL of seawater, using a simplified version of above methods. Analyses of multiple aliquots of six seawater samples yield a reproducibility of about ±1 to ±10% (1sd) for Pb concentrations of between 7 and 50 pmol/kg, where precision was primarily limited by the uncertainty of the blank correction (12±4 pg; 1sd). For the Pb isotope analyses, typical reproducibilities (±2sd) of 700-1500 ppm and 1000-2000 ppm were achieved for (207)Pb/(206)Pb, (208)Pb/(206)Pb and (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb, respectively. These results are superior to literature data that were obtained using plasma source mass spectrometry and they are at least a factor of five more precise for ratios involving the minor (204)Pb isotope. Both Pb concentration and isotope data, furthermore, show good agreement with published results for two seawater intercomparison samples of the GEOTRACES program. Finally, the new methods were applied to a seawater depth profile from the eastern South Atlantic. Both Pb contents and isotope compositions display a smooth evolution with depth, and no obvious outliers. Compared to previous Pb isotope data for seawater, the (206)Pb/(204)Pb ratios are well correlated

  3. Trophic Interactions in Louisiana Salt Marshes: Combining Stomach Content, Stable Isotope, and Fatty Acid Approaches

    Science.gov (United States)

    Lopez-Duarte, P. C.; Able, K.; Fodrie, J.; McCann, M. J.; Melara, S.; Noji, C.; Olin, J.; Pincin, J.; Plank, K.; Polito, M. J.; Jensen, O.

    2016-02-01

    Multiple studies conducted over five years since the 2010 Macondo oil spill in the Gulf of Mexico indicate that oil impacts vary widely among taxonomic groups. For instance, fishes inhabiting the marsh surface show no clear differences in either community composition or population characteristics between oiled and unoiled sites, despite clear evidence of physiological impacts on individual fish. In contrast, marsh insects and spiders are sensitive to the effects of hydrocarbons. Both insects and spiders are components of the marsh food web and represent an important trophic link between marsh plants and higher trophic levels. Because differences in oil impacts throughout the marsh food web have the potential to significantly alter food webs and energy flow pathways and reduce food web resilience, our goal is to quantify differences in marsh food webs between oiled and unoiled sites to test the hypothesis that oiling has resulted in simpler and less resilient food webs. Diets and food web connections were quantified through a combination of stomach content, stable isotope, and fatty acid analysis. The combination of these three techniques provides a more robust approach to quantifying trophic relationships than any of these methods alone. Stomach content analysis provides a detailed snapshot of diets, while fatty acid and stable isotopes reflect diets averaged over weeks to months. Initial results focus on samples collected in May 2015 from a range of terrestrial and aquatic consumer species, including insects, mollusks, crustaceans, and piscivorous fishes.

  4. Monitoring of carbon isotope composition of snow cover for Tomsk region

    Science.gov (United States)

    Akulov, P. A.; Volkov, Y. V.; Kalashnikova, D. A.; Markelova, A. N.; Melkov, V. N.; Simonova, G. V.; Tartakovskiy, V. A.

    2016-11-01

    This article shows the potential of using δ13C values of pollutants in snow pack to study the human impact on the environment of Tomsk and its surroundings. We believe that it is possible to use a relation between the isotope compositions of a fuel and black carbon for establishing the origin of the latter. The main object of our investigation was dust accumulated by the snow pack in the winter of 2015-2016. The study of dust samples included the following steps: determination of the total carbon content in snow pack samples of Tomsk and its surroundings, extraction of black carbon from the dust, as well as the determination of δ13C values of the total and black carbon accumulated in the snow pack. A snow survey was carried out on the 26th of January and on the 18th of March. The relative carbon content in the dust samples was determined by using an EA Flash 2000 element analyzer. It varied from 3 to 24%. The maximum carbon content was in the dust samples from areas of cottage building with individual heating systems. The δ13C values of the total and black carbon were determined by using a DELTA V Advantage isotope mass spectrometer (TomTsKP SB RAS). The isotope composition of black carbon corresponded to that of the original fuel. This fact allowed identifying the origin of black carbon in some areas of Tomsk.

  5. Investigations of isotopic composition of foodstuff - basic study and applications

    International Nuclear Information System (INIS)

    Wierzchnicki, R.

    2005-01-01

    Study of food isotopic composition play actually an important role in food authenticity and origin control. In Institute of Nuclear Chemistry and technology the subject of study has been investigated for many years. In last time our work is concentrated on the implementation new methods for selected food and improves of our proficiency in laboratory work. The examples of our study results are presented. (author)

  6. Investigations on isotopic composition of dusty mist of southern Tajikistan

    International Nuclear Information System (INIS)

    Abdullaev, S.F.; Abdurasulova, N.A.; Maslov, V.A.; Madvaliev, U.; Juraev, A.A.; Davlatshoev, T. S.U.

    2012-01-01

    Atmosphere physics laboratory under S.U. Umarov Physical and Technical Institute Academy of Sciences of the Republic of Tajikistan have carried out investigations on optical and micro physical properties of arid zone aerosols from 1982. Traces of man-made radioactive isotopes were revealed in sands and dust compositions taken in arid zone of Tajikistan during Soviet-American tests on investigation of arid aerosol. Produced result was the basis for further investigation of element composition for dusty haze distributed from south till central part of the country. We investigated samples of soil collected by natural sedimentation along dusty haze distribution and samples of dusty aerosol (in total 80 samples).

  7. 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.

  8. Seasonal trends of NH4+ and NO3- nitrogen isotope composition in rain collected at Juelich, Germany

    International Nuclear Information System (INIS)

    Freyer, H.D.

    1978-01-01

    Data are presented on nitrogen isotope composition in ammonium and nitrate from rain-water collected over 2 years in an interior area at Juelich, Germany. The seasonal trends in these data are discussed relative to natural and anthropogenic emissions of nitrogen compounds which additionally have been measured or estimated in their isotope composition, e.g. ammonia from animal urine, fuel combustion, fertilizer use and organic soil nitrogen, and natural and anthropogenic nitric oxides from automobile exhausts as well. The 15 N content of Juelich rain ammonium is found to be different from values of Hoering (1957) and Moore (1974) and from other rain samples collected in coastal areas. (Auth.)

  9. The oxygen isotopic composition of water extracted from unequilibrated ordinary chondrites

    OpenAIRE

    Baker, L.; Franchi, I.A.; Wright, I.P.; Pillinger, C.T.

    2003-01-01

    The oxygen isotopic composition of water extracted from the unequilibrated ordinary chondrites Semarkona and Bishunpur reveals differences in alteration mineralogy and levels of isotopic enrichment – reflecting key parameters in the alteration process.

  10. Oxygen isotopic composition of carbon dioxide in the middle atmosphere.

    Science.gov (United States)

    Liang, Mao-Chang; Blake, Geoffrey A; Lewis, Brenton R; Yung, Yuk L

    2007-01-02

    The isotopic composition of long-lived trace molecules provides a window into atmospheric transport and chemistry. Carbon dioxide is a particularly powerful tracer, because its abundance remains >100 parts per million by volume (ppmv) in the mesosphere. Here, we successfully reproduce the isotopic composition of CO(2) in the middle atmosphere, which has not been previously reported. The mass-independent fractionation of oxygen in CO(2) can be satisfactorily explained by the exchange reaction with O((1)D). In the stratosphere, the major source of O((1)D) is O(3) photolysis. Higher in the mesosphere, we discover that the photolysis of (16)O(17)O and (16)O(18)O by solar Lyman-alpha radiation yields O((1)D) 10-100 times more enriched in (17)O and (18)O than that from ozone photodissociation at lower altitudes. This latter source of heavy O((1)D) has not been considered in atmospheric simulations, yet it may potentially affect the "anomalous" oxygen signature in tropospheric CO(2) that should reflect the gross carbon fluxes between the atmosphere and terrestrial biosphere. Additional laboratory and atmospheric measurements are therefore proposed to test our model and validate the use of CO(2) isotopic fractionation as a tracer of atmospheric chemical and dynamical processes.

  11. Dietary interpretations for extinct megafauna using coprolites, intestinal contents and stable isotopes: Complimentary or contradictory?

    Science.gov (United States)

    Rawlence, Nicolas J.; Wood, Jamie R.; Bocherens, Herve; Rogers, Karyne M.

    2016-06-01

    For many extinct species, direct evidence of diet (e.g. coprolites, gizzard/intestinal contents) is not available, and indirect dietary evidence (e.g. stable isotopes) must be relied upon. The Late Holocene fossil record of New Zealand provides a unique opportunity to contrast palaeodietary reconstructions for the extinct moa (Aves: Dinornithiformes) using stable isotopes and coprolite/gizzard contents. Palaeodietary reconstructions from isotopes are found to contradict those based on direct dietary evidence. We discuss reasons for this and advocate, where possible, for the use of multiple lines of evidence in reconstructing the diets of extinct species.

  12. Does burial diagenesis reset pristine isotopic compositions in paleosol carbonates?

    Science.gov (United States)

    Bera, M. K.; Sarkar, A.; Tandon, S. K.; Samanta, A.; Sanyal, P.

    2010-11-01

    Sedimentological study of early Oligocene continental carbonates from the fluvial Dagshai Formation of the Himalayan foreland basin, India resulted in the recognition of four different types namely, soil, palustrine, pedogenically modified palustrine and groundwater carbonates. Stable oxygen and carbon isotopic ( δ18O and δ13C) analyses of fabric selective carbonate microsamples show that although the pristine isotopic compositions are largely altered during deep-burial diagenesis, complete isotopic homogenization does not occur. δ18O and δ13C analyses of ~ 200 calcrete and palustrine carbonates from different stratigraphic horizons and comparison with δ18O of more robust bioapatite (fossil vertebrate tooth) phase show that dense micrites (~ > 70% carbonate) invariably preserve the pristine δ18O value (mean) of ~ - 9.8‰, while altered carbonates show much lower δ18O value ~ - 13.8‰. Such inhomogeneity causes large intra-sample and intra-soil profile variability as high as > 5‰, suggesting that soils behave like a closed system where diagenetic overprinting occurs in local domains. A simple fluid-rock interaction model suggests active participation of clay minerals to enhance the effect of fluid-rock ratio in local domains during diagenesis. This places an upper limit of 70% micrite concentration above which the effect of diagenetic alteration is minimal. Careful sampling of dense micritic part of the soil carbonate nodules, therefore, does provide pristine isotopic composition and it is inappropriate, as proposed recently, to reject the paleoclimatic potential of all paleosol carbonates affected by burial diagenesis. Based on pristine δ13C value of - 8.8 ± 0.2‰ in soil carbonates an atmospheric CO 2 concentration between ~ 764 and ~ 306 ppmv is estimated for the early Oligocene (~ 31 Ma) Dagshai time. These data show excellent agreement between two independent proxy records (viz. soil carbonate and marine alkenone) and support early Oligocene

  13. Origin of the Moon Unveiled by its Heavy Iron Isotope Composition

    Science.gov (United States)

    Poitrasson, F.; Halliday, A. N.; Lee, D.; Levasseur, S.; Teutsch, N.

    2002-12-01

    The origin of the Moon has long been of interest and although the Giant Impact theory is currently the preferred explanation, unequivocal supporting evidence has been lacking. We have measured the iron isotope compositions of Shergotty-Nakhla-Chassigny meteorites and eucrites thought to come from Mars and Vesta, as well as samples from the Moon and the mafic Earth using high precision plasma source mass spectrometry. The mean iron isotope composition of the lunar samples, expressed in the conventional delta notation (d57Fe/54Fe) with respect to the IRMM-14 isotopic standard, is heavier (0.221 per mil (0.041: one standard deviation, 10 samples)) than those of the Earth (0.119 per mil (0.044, 7 samples)), which themselves are heavier than Martian meteorites (0.009 per mil (0.024, 6 samples)) and the eucrites measured (0.033 per mil (0.038, 7 samples)). Student's t-test calculations show that the Moon and Earth means are different from each other and from those of the other planetary bodies at >99% level of significance. The iron isotope compositions show no simple relationship with planetary heliocentric position, mantle oxygen fugacity, volatile content, or planet size. Similarly, these results do not support an origin of the Moon through co-accretion with the Earth, or as a fragment ejected from the Earth's mantle, or as another planet captured by the early Earth. In contrast, these data can be explained if the Earth, and especially the Moon, went through partial vaporisation and condensation leading to kinetic iron isotopic fractionation. Our data are also consistent with the suggested levels of enrichment of refractory elements for the bulk Earth and Moon. These new iron isotope results thus provide strong support for the origin of the Moon through a giant impact between the proto-Earth and another planet. Raleigh kinetic fractionation calculations indicate that only 1% loss of the current Fe budget of the Moon is required to explain its heavier isotopic

  14. Seasonal variation in stomach contents and diet composition in the ...

    African Journals Online (AJOL)

    Seasonal variation in stomach contents and diet composition in the large girdled lizard, Cordylus giganteus (Reptilia: Cordylidae) in the Highveld grasslands of the northeastern Free State, South Africa.

  15. Stable isotope composition of atmospheric carbon monoxide. A modelling study

    International Nuclear Information System (INIS)

    Gromov, Sergey S.

    2014-01-01

    This study aims at an improved understanding of the stable carbon and oxygen isotope composition of the carbon monoxide (CO) in the global atmosphere by means of numerical simulations. At first, a new kinetic chemistry tagging technique for the most complete parameterisation of isotope effects has been introduced into the Modular Earth Submodel System (MESSy) framework. Incorporated into the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model, an explicit treatment of the isotope effects on the global scale is now possible. The expanded model system has been applied to simulate the chemical system containing up to five isotopologues of all carbon- and oxygen-bearing species, which ultimately determine the δ 13 C, δ 18 O and Δ 17 O isotopic signatures of atmospheric CO. As model input, a new stable isotope-inclusive emission inventory for the relevant trace gases has been compiled. The uncertainties of the emission estimates and of the resulting simulated mixing and isotope ratios have been analysed. The simulated CO mixing and stable isotope ratios have been compared to in-situ measurements from ground-based observatories and from the civil-aircraft-mounted CARIBIC-1 measurement platform. The systematically underestimated 13 CO/ 12 CO ratios of earlier, simplified modelling studies can now be partly explained. The EMAC simulations do not support the inferences of those studies, which suggest for CO a reduced input of the highly depleted in 13 C methane oxidation source. In particular, a high average yield of 0.94 CO per reacted methane (CH 4 ) molecule is simulated in the troposphere, to a large extent due to the competition between the deposition and convective transport processes affecting the CH 4 to CO reaction chain intermediates. None of the other factors, assumed or disregarded in previous studies, however hypothesised to have the potential in enriching tropospheric CO in 13 C, were found significant when explicitly simulated. The

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

    Science.gov (United States)

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

    2007-04-04

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

  17. Isotopic composition of cosmic-ray boron and nitrogen

    Science.gov (United States)

    Krombel, K. E.; Wiedenbeck, M. E.

    1988-01-01

    New measurements of the cosmic-ray boron and nitrogen isotopes at earth and of the elemental abundances of boron, carbon, nitrogen, and oxygen are presented. A region of mutually allowed values for the cosmic-ray nitrogen source ratios is determined, and the cosmic-ray escape mean free path is determined as a function of energy using a leaky box model for cosmic-ray propagation in the Galaxy. Relative to O-16, a N-15 source abundance consistent with solar system composition and a N-14 source abundance which is a factor of about three underabundant relative to the solar value are found.

  18. Uranium isotope composition of a laterite profile during extreme weathering of basalt in Guangdong, South China

    Science.gov (United States)

    Huang, J.; Zhou, Z.; Gong, Y.; Lundstrom, C.; Huang, F.

    2015-12-01

    Rock weathering and soil formation in the critical zone are important for material cycle from the solid Earth to superficial system. Laterite is a major type of soil in South China forming at hot-humid climate, which has strong effect on the global uranium cycle. Uranium is closely related to the environmental redox condition because U is stable at U(Ⅳ) in anoxic condition and U(Ⅵ) as soluble uranyl ion (UO22+) under oxic circumstance. In order to understand the behavior of U isotopes during crust weathering, here we report uranium isotopic compositions of soil and base rock samples from a laterite profile originated from extreme weathering of basalt in Guangdong, South China. The uranium isotopic data were measured on a Nu Plasma MC-ICP-MS at the University of Illinois at Urbana-Champaign using the double spike method. The δ238U of BCR-1 is -0.29±0.03‰ (relative to the international standard CRM-112A), corresponding to a 238U/235U ratio of 137.911±0.004. Our result of BCR-1 agrees with previous analyses (e.g., -0.28‰ in Weyer et al. 2008) [1]. U contents of the laterite profile decrease from 1.9 ppm to 0.9 ppm with depth, and peak at 160 - 170 cm (2.3 ppm), much higher than the U content of base rocks (~0.5 ppm). In contrary, U/Th of laterites is lower than that of base rock (0.27) except the peak at the depth of 160-170 cm (0.38), indicating significant U loss during weathering. Notably, U isotope compositions of soils show a small variation from -0.38 to -0.28‰, consistent with the base rock within analytical error (0.05‰ to 0.08‰, 2sd). Such small variation can be explained by a "rind effect" (Wang et al., 2015) [2], by which U(Ⅳ) can be completely oxidized to U(VI) layer by layer during basalt weathering by dissolved oxygen. Therefore, our study indicates that U loss during basalt weathering at the hot-humid climate does not change U isotope composition of superficial water system. [1] Weyer S. et al. (2008) Natural fractionation of 238U/235

  19. Oxygen isotopic compositions of asteroidal materials returned from Itokawa by the Hayabusa mission.

    Science.gov (United States)

    Yurimoto, Hisayoshi; Abe, Ken-ichi; Abe, Masanao; Ebihara, Mitsuru; Fujimura, Akio; Hashiguchi, Minako; Hashizume, Ko; Ireland, Trevor R; Itoh, Shoichi; Katayama, Juri; Kato, Chizu; Kawaguchi, Junichiro; Kawasaki, Noriyuki; Kitajima, Fumio; Kobayashi, Sachio; Meike, Tatsuji; Mukai, Toshifumi; Nagao, Keisuke; Nakamura, Tomoki; Naraoka, Hiroshi; Noguchi, Takaaki; Okazaki, Ryuji; Park, Changkun; Sakamoto, Naoya; Seto, Yusuke; Takei, Masashi; Tsuchiyama, Akira; Uesugi, Masayuki; Wakaki, Shigeyuki; Yada, Toru; Yamamoto, Kosuke; Yoshikawa, Makoto; Zolensky, Michael E

    2011-08-26

    Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 Itokawa returned by the Hayabusa spacecraft. Compositions of the particles are depleted in (16)O relative to terrestrial materials and indicate that Itokawa, an S-type asteroid, is one of the sources of the LL or L group of equilibrated ordinary chondrites. This is a direct oxygen-isotope link between chondrites and their parent asteroid.

  20. V isotope composition in modern marine hydrothermal sediments

    Science.gov (United States)

    Wu, F.; Owens, J. D.; Nielsen, S.; German, C. R.; Rachel, M.

    2017-12-01

    Vanadium is multivalence transition metal with two isotopes (51V and 50V). Recent work has shown that large V isotope variations occur with oxygen variations in modern sediments (Wu et al., 2016 and 2017 Goldschmidt Abstracts), providing its potential as a promising proxy for determining low oxygen conditions. However, the development of V isotopes as a proxy to probe past redox conditions requires a comprehensive understanding of the modern oceanic isotopic mass balance. Therein, the scavenging of V from the hydrous iron oxides in hydrothermal fluid has been shown to be an important removal process from seawater (Rudnicki and Elderfield, 1993 GCA) but remains unquantified. In this study, we analyzed V isotopic compositions of metalliferous sediments around the active TAG hydrothermal mound from the mid-Atlantic Ridge (26° degrees North) and the Eastern Pacific Zonal Transect (GEOTRACES EPZT cruise GP16). The TAG sediments deposited as Fe oxyhydroxides from plume fall-out, and have δ51V values between -0.3 to 0‰. The good correlation between Fe and V for these metalliferous sediments indicate that the accumulation of V in these samples is directly related to the deposition of Fe oxyhydroxides, which also control their V isotope signature. The EPZT samples cover 8,000 km in the South Pacific Ocean with sedimentary areas that underlie the Peru upwelling region and the well-oxygenated deep South Pacific Ocean influenced by hydtorthermal plume material from southern East Pacific Rise (EPR). The sediments collected at the east of the EPR have δ51V values between -1.2 to -0.7‰, similar to previous δ51V of oxic sediments. In contrast, the sediments from the west of the EPR have δ51V values (-0.4 to 0‰) similar to hydrothermal sediments from the mid-Atlantic Ridge, indicating the long transportation (more than 4,000 km, Fitzsimmons et al., 2017 NG) of Fe and Mn from hydrothermal plume and their incorporation into sediments have a major impact on the cycle of V

  1. Variability of Fe isotope compositions of hydrothermal sulfides and oxidation products at mid-ocean ridges

    Science.gov (United States)

    Li, Xiaohu; Wang, Jianqiang; Chu, Fengyou; Wang, Hao; Li, Zhenggang; Yu, Xing; Bi, Dongwei; He, Yongsheng

    2018-04-01

    Significant Fe isotopic fractionation occurs during the precipitation and oxidative weathering of modern seafloor hydrothermal sulfides, which has an important impact on the cycling of Fe isotopes in the ocean. This study reports the Fe-isotope compositions of whole-rock sulfides and single-mineral pyrite collected from hydrothermal fields at the South Mid-Atlantic Ridge (SMAR) and the East Pacific Rise (EPR) and discusses the impacts of precipitation and late-stage oxidative weathering of sulfide minerals on Fe isotopic fractionation. The results show large variation in the Fe-isotope compositions of the sulfides from the different hydrothermal fields on the mid-oceanic ridges, indicating that relatively significant isotope fractionation occurs during the sulfide precipitation and oxidative weathering processes. The Fe-isotope compositions of the sulfides from the study area at the SMAR vary across a relatively small range, with an average value of 0.01‰. This Fe-isotope composition is similar to the Fe-isotope composition of mid-oceanic ridge basalt, which suggests that Fe was mainly leached from basalt. In contrast, the Fe-isotope composition of the sulfides from the study area at the EPR are significantly enriched in light Fe isotopes (average value - 1.63‰), mainly due to the kinetic fractionation during the rapid precipitation process of hydrothermal sulfide. In addition, the pyrite from different hydrothermal fields is enriched in light Fe isotopes, which is consistent with the phenomenon in which light Fe isotopes are preferentially enriched during the precipitation of pyrite. The red oxides have the heaviest Fe-isotope compositions (up to 0.80‰), indicating that heavy Fe isotopes are preferentially enriched in the oxidation product during the late-stage oxidation process. The data obtained from this study and previous studies show a significant difference between the Fe-isotope compositions of the sulfides from the SMAR and EPR. The relatively heavy

  2. The use of oxygen isotopic composition to study water dynamics in Amazon floodplain lakes

    International Nuclear Information System (INIS)

    Martinelli, L.A.; Mortatti, J.; Victoria, R.L.; Matsui, E.

    1989-01-01

    The lakes formed in the Amazon floodplain play a key role in sustaining the highest populational density in the Amazon Basin because of its high primary productivity. The water volume in these lakes vary greatly during the year and possible water sources are the feeding river during high water state of the hydrographs and local inputs from its drainage basin. As these sources are chemically distinct, to understand the nutrient dynamics in these lakes, it is very important to know the relative water contribution of different water sources. In this paper we use 18 O as a conservative to know the water sources for the lakes and our hypothesis is that: 1) In the high water stage lake water is derived predominantly from its feeding river. Therefore their δ 18 O should be similar. 2) In the low water stage lake water is a mixture of watershed and last flood event waters. In this case, lake δ 18 O should be indicative of the relative contribution of each source. To test this hypothesis we assume a two end member mixing a model. If the 18 O isotopic composition of these two sources are known the relative contribution of each source may be calculated by isotopic dilution equation. The first step in this work was to know the 18 O isotopic composition of the lakes and feeding rivers and its spatial and temporal variability. Clearly the δ 18 O signal in the lakes of Amazon varzea is controlled by the 18 O content of the feeding river. But there is a consistent pattern in the 18 O enrichment of the lakes versus the feeding rivers, which is most pronounced on low water period. Our initial hypothesis requires that this water be of local drainage basin origin. Although it was not possible to measure the isotopic composition of local drainage water, indirect measurement suggest that this could be the case. (author). 17 refs, 4 figs, 2 tabs

  3. The effect of natural weathering on the chemical and isotopic composition of biotites

    International Nuclear Information System (INIS)

    Clauer, N.; Bonnot-Courtois, C.

    1982-01-01

    The effect of progressive natural weathering on the isotopic (Rb-Sr, K-Ar, deltaD, delta 18 O) and chemical (REE, H 2 O + ) compositions of biotite has been studied on a suite of migmatitic biotites from the Chad Republic. During the early stages of weathering the Rb-Sr system is strongly affected, the hydrogen and oxygen isotope compositions change markedly, the minerals are depleted in light REE, the water content increases by a factor of two, and the K-Ar system is relatively little disturbed. During intensive weathering the K-Ar system is more strongly disturbed than the Rb-Sr system. Most of the isotopic and chemical modifications take place under nonequilibrium conditions and occur before newly formed kaolinite and/or smectite can be detected. These observations suggest that (a) 'protominerals' may form within the biotite structure during the initial period of weathering, and (b) only when chemical equilibrium is approached in the weathering profile are new minerals able to form. (author)

  4. Lead contamination and transfer in urban environmental compartments analyzed by lead levels and isotopic compositions

    International Nuclear Information System (INIS)

    Hu, Xin; Sun, Yuanyuan; Ding, Zhuhong; Zhang, Yun; Wu, Jichun; Lian, Hongzhen; Wang, Tijian

    2014-01-01

    Lead levels and isotopic compositions in atmospheric particles (TSP and PM 2.5 ), street dust and surface soil collected from Nanjing, a mega city in China, were analyzed to investigate the contamination and the transfer of lead in urban environmental compartments. The lead contents in TSP and PM 2.5 are significantly higher than them in the surface soil and street dust (p  206 Pb/ 207 Pb vs. 208 Pb/ 206 Pb and 206 Pb/ 207 Pb vs. 1/Pb imply that the street dust and atmospheric particles (TSP and PM 2.5 ) have very similar lead sources. Coal emissions and smelting activities may be the important lead sources for street dust and atmospheric particles (TSP and PM 2.5 ), while the deposition of airborne lead is an important lead source for urban surface soil. - Highlights: • Lead levels and isotope ratios in atmospheric particles, street dust and surface soil. • Significant enrichment of lead in atmospheric particles was observed. • Street dust and atmospheric particles have similar lead sources. • Endmembers of soil lead differ from street dust and atmospheric particles. • Airborne lead poses the main risks to unban environmental quality. - Transfer of airborne particle bound lead into street dust and surface soil in unban environmental based on lead levels and isotopic compositions

  5. [Hydrogen and Oxygen Isotopic Compositions of Precipitation and Its Water Vapor Sources in Eastern Qaidam Basin].

    Science.gov (United States)

    Zhu, Jian-jia; Chen, Hui; Gong, Guo-li

    2015-08-01

    Stable hydrogen and oxygen isotopes can be used as a tracer to analyze water vapor sources of atmospheric precipitation. We choose Golmud and Delingha as our study areas, Golmud locates in the south of Qaidam basin, and Delingha locates in the northeast. Based on the analysis of monthly change of hydrogen and oxygen isotopic compositions of precipitation during June to September of 2010, and the relationship between deltaD and delta18O in precipitation, we investigated the water vapor sources of precipitation in eastern Qaidam basin. The results show that: (1) meteoric water line between June to September in Golmud is: deltaD = 7.840 delta18O - 4.566 (R2 = 0.918, P isotopes. However, the delta18O content of precipitation becomes lower from late July to early September, especially for the late September. The 8180 content of precipitation in Delingha is higher in June to August than that in late September. (3) the water vapor sources of precipitation in Golmud and Delingha are different, Golmud area is the northern border of Qinghai-Tibet Plateau where the southwest monsoon can reach, and the southwest monsoon brings water vapors of precipitation, but the water vapors of precipitation in Delingha are mainly from local evaporation.

  6. Interpreting bryophyte stable carbon isotope composition: Plants as temporal and spatial climate recorders

    Science.gov (United States)

    Royles, Jessica; Horwath, Aline B.; Griffiths, Howard

    2014-04-01

    are unable to control tissue water content although physiological adaptations allow growth in a wide range of habitats. Carbon isotope signals in two mosses (Syntrichia ruralis and Chorisodontium aciphyllum) and two liverworts (Conocephalum conicum and Marchantia polymorpha), whether instantaneous (real time, Δ13C), or organic matter (as δ13COM), provide an assimilation-weighted summary of bryophyte environmental adaptations. In mosses, δ13COM is within the measured range of Δ13C values, which suggests that other proxies, such as compound-specific organic signals, will be representative of historical photosynthetic and growth conditions. The liverworts were photosynthetically active over a wider range of relative water contents (RWC) than the mosses. There was a consistent 5‰ offset between Δ13C values in C. conicum and M. polymorpha, suggestive of greater diffusion limitation in the latter. Analysis of a C. aciphyllum moss-peat core showed the isotopic composition over the past 200 years reflects recent anthropogenic CO2 emissions. Once corrected for source-CO2 inputs, the seasonally integrated Δ13COM between 1350 and 2000 A.D. varied by 1.5‰ compared with potential range of the 12‰ measured experimentally, demonstrating the relatively narrow range of conditions under which the majority of net assimilation takes place. Carbon isotope discrimination also varies spatially, with a 4‰ shift in epiphytic bryophyte organic matter found between lowland Amazonia and upper montane tropical cloud forest in the Peruvian Andes, associated with increased diffusion limitation.

  7. Continuous measurements of isotopic composition of water vapour on the East Antarctic Plateau

    Directory of Open Access Journals (Sweden)

    M. Casado

    2016-07-01

    Full Text Available Water stable isotopes in central Antarctic ice cores are critical to quantify past temperature changes. Accurate temperature reconstructions require one to understand the processes controlling surface snow isotopic composition. Isotopic fractionation processes occurring in the atmosphere and controlling snowfall isotopic composition are well understood theoretically and implemented in atmospheric models. However, post-deposition processes are poorly documented and understood. To quantitatively interpret the isotopic composition of water archived in ice cores, it is thus essential to study the continuum between surface water vapour, precipitation, surface snow and buried snow. Here, we target the isotopic composition of water vapour at Concordia Station, where the oldest EPICA Dome C ice cores have been retrieved. While snowfall and surface snow sampling is routinely performed, accurate measurements of surface water vapour are challenging in such cold and dry conditions. New developments in infrared spectroscopy enable now the measurement of isotopic composition in water vapour traces. Two infrared spectrometers have been deployed at Concordia, allowing continuous, in situ measurements for 1 month in December 2014–January 2015. Comparison of the results from infrared spectroscopy with laboratory measurements of discrete samples trapped using cryogenic sampling validates the relevance of the method to measure isotopic composition in dry conditions. We observe very large diurnal cycles in isotopic composition well correlated with temperature diurnal cycles. Identification of different behaviours of isotopic composition in the water vapour associated with turbulent or stratified regime indicates a strong impact of meteorological processes in local vapour/snow interaction. Even if the vapour isotopic composition seems to be, at least part of the time, at equilibrium with the local snow, the slope of δD against δ18O prevents us from identifying

  8. Calcium isotopic fractionation in mantle peridotites by melting and metasomatism and Ca isotope composition of the Bulk Silicate Earth

    Science.gov (United States)

    Kang, Jin-Ting; Ionov, Dmitri A.; Liu, Fang; Zhang, Chen-Lei; Golovin, Alexander V.; Qin, Li-Ping; Zhang, Zhao-Feng; Huang, Fang

    2017-09-01

    To better constrain the Ca isotopic composition of the Bulk Silicate Earth (BSE) and explore the Ca isotope fractionation in the mantle, we determined the Ca isotopic composition of 28 peridotite xenoliths from Mongolia, southern Siberia and the Siberian craton. The samples are divided in three chemical groups: (1) fertile, unmetasomatized lherzolites (3.7-4.7 wt.% Al2O3); (2) moderately melt-depleted peridotites (1.3-3.0 wt.% Al2O3) with no or very limited metasomatism (LREE-depleted cpx); (3) strongly metasomatized peridotites (LREE-enriched cpx and bulk rock) further divided in subgroups 3a (harzburgites, 0.1-1.0% Al2O3) and 3b (fertile lherzolites, 3.9-4.3% Al2O3). In Group 1, δ44/40Ca of fertile spinel and garnet peridotites, which experienced little or no melting and metasomatism, show a limited variation from 0.90 to 0.99‰ (relative to SRM 915a) and an average of 0.94 ± 0.05‰ (2SD, n = 14), which defines the Ca isotopic composition of the BSE. In Group 2, the δ44/40Ca is the highest for three rocks with the lowest Al2O3, i.e. the greatest melt extraction degrees (average 1.06 ± 0.04 ‰, i.e. ∼0.1‰ heavier than the BSE estimate). Simple modeling of modal melting shows that partial melting of the BSE with 103 ln ⁡αperidotite-melt ranging from 0.10 to 0.25 can explain the Group 2 data. By contrast, δ44/40Ca in eight out of nine metasomatized Group 3 peridotites are lower than the BSE estimate. The Group 3a harzburgites show the greatest δ44/40Ca variation range (0.25-0.96‰), with δ44/40Ca positively correlated with CaO and negatively correlated with Ce/Eu. Chemical evidence suggests that the residual, melt-depleted, low-Ca protoliths of the Group 3a harzburgites were metasomatized, likely by carbonate-rich melts/fluids. We argue that such fluids may have low (≤0.25‰) δ44/40Ca either because they contain recycled crustal components or because Ca isotopes, similar to trace elements and their ratios, may be fractionated by kinetic and

  9. Spectroscopic metrology for isotope composition measurements and transfer standards

    Science.gov (United States)

    Anyangwe Nwaboh, Javis; Balslev-Harder, David; Kääriäinen, Teemu; Richmond, Craig; Manninen, Albert; Mohn, Joachim; Kiseleva, Maria; Petersen, Jan C.; Werhahn, Olav; Ebert, Volker

    2017-04-01

    The World Meteorological Organization (WMO) has identified greenhouse gases such as CO2, CH4 and N2O as critical for global climate monitoring. Other molecules such as CO that has an indirect effect of enhancing global warming are also monitored. WMO has stated compatibility goals for atmospheric concentration and isotope ratio measurements of these gases, e.g. 0.1 ppm for CO2 concentration measurements in the northern hemisphere and 0.01 ‰ for δ13C-CO2. For measurements of the concentration of greenhouse gases, gas analysers are typically calibrated with static gas standards e.g. traceable to the WMO scale or to the International System of Units (SI) through a national metrology institute. However, concentrations of target components, e.g. CO, in static gas standards have been observed to drift, and typically the gas matrix as well as the isotopic composition of the target component does not always reflect field gas composition, leading to deviations of the analyser response, even after calibration. The deviations are dependent on the measurement technique. To address this issue, part of the HIGHGAS (Metrology for high-impact greenhouse gases) project [1] focused on the development of optical transfer standards (OTSs) for greenhouse gases, e.g. CO2 and CO, potentially complementing gas standards. Isotope ratio mass spectrometry (IRMS) [2] is currently used to provide state-of-the-art high precision (in the 0.01 ‰ range) measurements for the isotopic composition of greenhouse gases. However, there is a need for field-deployable techniques such as optical isotope ratio spectroscopy (OIRS) that can be combined with metrological measurement methods. Within the HIGHGAS project, OIRS methods and procedures based on e.g. cavity enhanced spectroscopy (CES) and tunable diode laser absorption spectroscopy (TDLAS), matched to metrological principles have been established for the measurement of 13C/12C and 18O/16O ratios in CO2, 15N/14N ratios in N2O, and 13C/12C and 2H

  10. Modeling the oxygen-isotopic composition of the North American Ice Sheet and its effect on the isotopic composition of the ocean during the last glacial cycle

    NARCIS (Netherlands)

    Sima, A.; Paul, A.; Schulz, M.; Oerlemans, J.

    2006-01-01

    We used a 2.5-dimensional thermomechanical icesheet model including the oxygen-isotope ratio 18O/16O as a passive tracer to simulate the isotopic composition (d18O) of the North American Ice Sheet (NAIS) during the last glacial cycle. This model allowed us to estimate the NAIS contribution to the

  11. Pb isotopic composition of the atmosphere of the Sao Paulo city, Brazil, and isotopic characterization of some pollutant sources

    International Nuclear Information System (INIS)

    Aily, C.; Babinski, M.; Ruiz, I.R.; Sato, K

    2001-01-01

    Lead isotopes are known to be good tools for surveying lead origin in atmospheric samples (Chow et al., 1975). Lead has four naturally occurring stable isotopes: 206 Pb, 207 Pb, 208 Pb and 204 Pb. The first three isotopes are end products of radioactive decay chains from 238 U, 235 U and 232 Th, respectively, and the last one is non-radiogenic. Therefore, their abundance and the ratios among the four isotopes gradually change with time. Lead in the atmosphere comes from various sources, such as leaded gasoline, industrial emissions and coal combustion. Thus, lead isotope ratios different from those of the mother rock in the region are often observed in the atmosphere (Tatsumoto and Patterson, 1963). Lead is emitted to the atmosphere in fine particles, which can be transported within air masses for very long distances, e. g. from mid latitude regions to the Artic and Antarctica (Sturges and Barrie, 1989). Lead isotopes have been used to trace the pollutant sources in many cities of the world. However, a systematic study using this methodology has not been done in any Brazilian city. The main purpose of the present work is to characterize the Pb isotope composition in the atmosphere in Sao Paulo city, and suggest the possible pollutant sources. For our study lead isotopes were measured in different samples: aerosols and rainwater which would yield the Pb isotope composition of the atmosphere. Samples of gasoline and ethanol, gutter sweepings, soot from vehicle exhaust pipes, and filters containing particulate material from industrial emissions were also analyzed, since they were considered potential pollutant sources of the atmosphere. In order to obtain the local geogenic Pb isotopic composition we also analyzed rock and K-feldspar samples. Lead concentrations were only determined on aerosols and rainwater samples (au)

  12. [Humus composition and stable carbon isotope natural abundance in paddy soil under long-term fertilization].

    Science.gov (United States)

    Ma, Li; Yang, Lin-Zhang; Ci, En; Wang, Yan; Yin, Shi-Xue; Shen, Ming-Xing

    2008-09-01

    Soil samples were collected from an experimental paddy field with long-term (26 years) fertilization in Taihu Lake region of Jiangsu Province to study the effects of different fertilization on the organic carbon distribution and stable carbon isotope natural abundance (delta 13C) in the soil profile, and on the humus composition. The results showed that long-term fertilization increased the organic carbon content in top soil significantly, and there was a significantly negative exponential correlation between soil organic carbon content and soil depth (P organic carbon content in 10-30 cm soil layer under chemical fertilizations and in 20-40 cm soil layer under organic fertilizations was relatively stable. Soil delta 13C increased gradually with soil depth, its variation range being from -24% per thousand to -28 per thousand, and had a significantly negative linear correlation with soil organic carbon content (P soil layer, the delta 13C in treatments organic manure (M), M + NP, M + NPK, M + straw (R) + N, and R + N decreased significantly; while in 30-50 cm soil layer, the delta 13C in all organic fertilization treatments except R + N increased significantly. Tightly combined humus (humin) was the main humus composition in the soil, occupying 50% or more, and the rest were loosely and stably combined humus. Long-term fertilization increased the content of loosely combined humus and the ratio of humic acid (HA) to fulvic acid (FA).

  13. Stable Cl isotope composition of the Changjiang River water

    Science.gov (United States)

    Lang, Y.; Liu, C. Q.; LI, S. L.; Aravena, R.; Ding, H.; WANG, B.; Benjamin, C.

    2017-12-01

    To understand chemical wreathing, nutrient cycling, and the impact of human activities on eco-environments of the Changjiang River (Yangtze River) Basin, we carried out a geochemical study on water chemistry and multiple isotopes (C, N, S, Sr…...) of Changjiang River water in the summer season. Some of the research results about the water chemistry, boron isotope geochemistry and suspended matter have been published (Chetelat et al., 2008; Li et al., 2010). Ten samples were selected for the measurement of δ37Cl values, among which 7 samples were collected from main stream and 3 samples from tributaries. The range of δ37Cl values varies between 0.02‰ and 0.33‰ in the main stream and between 0.16‰ and 0.71‰ in the tributary waters. The δ37Cl values in general are negatively correlated with Cl- concentrations for both main stream and tributary waters. δ37Cl value of Wujiang, which is one of the large tributaries in the upper reach of Changjiang and dominated by carbonate rocks in lithology of the watershed, has the maximum value but minimum value of Cl- concentration in this study. The lowest δ37Cl value was measured for the water collected from the estuary of Changjiang River. The variation of δ37Cl values in the waters would be attributed to mixing of different sources of chlorine, which most likely include rain water, ground water, seawater, and pollutants. Systematic characterization of different Cl sources in terms of their chlorine isotope composition is imperative for better understanding of sources and processes of chlorine cycling. Acknowledgements: This work was financially supported by NSFC through project 41073099. (Omit references)

  14. Alteration of the Carbon and Nitrogen Isotopic Composition in the Martian Surface Rocks Due to Cosmic Ray Exposure

    Science.gov (United States)

    Pavlov, A. A.; Pavlov, A. K.; Ostryakov, V. M.; Vasilyev, G. I.; Mahaffy, P.; Steele, A.

    2014-01-01

    C-13/C-12 and N-15/N-14 isotopic ratios are pivotal for our understanding of the Martian carbon cycle, history of the Martian atmospheric escape, and origin of the organic compounds on Mars. Here we demonstrate that the carbon and nitrogen isotopic composition of the surface rocks on Mars can be significantly altered by the continuous exposure of Martian surface to cosmic rays. Cosmic rays can effectively produce C-13 and N-15 isotopes via spallation nuclear reactions on oxygen atoms in various Martian rocks. We calculate that in the top meter of the Martian rocks, the rates of production of both C-13 and N-15 due to galactic cosmic rays (GCRs) exposure can vary within 1.5-6 atoms/cm3/s depending on rocks' depth and chemical composition. We also find that the average solar cosmic rays can produce carbon and nitrogen isotopes at a rate comparable to GCRs in the top 5-10 cm of the Martian rocks. We demonstrate that if the total carbon content in a surface Martian rock is rocks with relatively short exposure ages (e.g., 100 million years), cosmogenic changes in N-15/N-14 ratio are still very significant. We also show that a short exposure to cosmic rays of Allan Hills 84001 while on Mars can explain its high-temperature heavy nitrogen isotopic composition (N-15/N-14). Applications to Martian meteorites and the current Mars Science Laboratory mission are discussed.

  15. Spatial patterns of throughfall isotopic composition at the event and seasonal timescales

    Science.gov (United States)

    Scott T. Allen; Richard F. Keim; Jeffrey J. McDonnell

    2015-01-01

    Spatial variability of throughfall isotopic composition in forests is indicative of complex processes occurring in the canopy and remains insufficiently understood to properly characterize precipitation inputs to the catchment water balance. Here we investigate variability of throughfall isotopic composition with the objectives: (1) to quantify the spatial variability...

  16. Carbon-13 and oxygen-18 isotope effects in the decarboxylation of nicotinic acid of natural isotopic composition

    International Nuclear Information System (INIS)

    Zielinski, M.; Zielinska, A.; Papiernik-Zielinska, H.; McKenzie, J.A.; Bernasconi, S.; Paul, H.

    1998-01-01

    Carbon-13 and oxygen-18 isotope effects in the decarboxylation of nicotinic acid of natural isotopic composition above and below its melting temperature have been studied and compared with the primary (PKIE) and secondary kinetic isotope effects (SKIE) of 13 C and 18 O, respectively, in the decarboxylation of other heterocyclic acids. The temperature dependence of the secondary oxygen-18 isotope effects is negative in the total 221-255 deg C temperature interval investigated initially. The 13 C KIE measured above melting point of N.A. (temperature interval 235-270 deg C) are located in the range 1.007-1.009. Below melting point of nicotinic acid the 13 C KIE are larger and reveal the negative temperature dependence ( 13 C KIE decreases with decreasing the reaction temperature from 1.013/at 230 deg C to 1.0114/at 221 deg C). A discussion of the above isotopic results is presented. (author)

  17. The effects of early diagenesis on the chemical and stable carbon isotopic composition of wood

    International Nuclear Information System (INIS)

    Spiker, E.C.; Hatcher, P.G.

    1987-01-01

    Studies of modern and ancient buried wood show that there is a linear correlation between carbohydrate content and the stable carbon isotope composition as carbohydrates are preferentially degraded during early diagenesis. As the carbohydrate content decreases, the delta 13 C value of the degraded wood decreases 1 to 2 per mil, approaching the value of the residual lignin. These results indicate that carbohydrate degradation products are lost and not incorporated into the aromatic structure as lignin is selectively preserved during early diagenesis of wood. These results also indicate that attempts to quantify terrestrial inputs to modern sedimentary organic matter based on delta 13 C values should consider the possibility of a 1 to 2 per mil decrease in the delta 13 C value of degraded wood. (author)

  18. Effect of temperature and salinity on stable isotopic composition of shallow water benthic foraminifera: A laboratory culture study

    Digital Repository Service at National Institute of Oceanography (India)

    Kurtarkar, S.R.; Linshy, V.N.; Saraswat, R.; Nigam, R.

    Quantitative estimation of past climatic parameters from stable isotopic composition of foraminifera relies on estimating the precise relationship between stable isotopic composition of the species analyzed and the physico-chemical factors...

  19. The isotopic composition of CO in vehicle exhaust

    Science.gov (United States)

    Naus, S.; Röckmann, T.; Popa, M. E.

    2018-03-01

    We investigated the isotopic composition of CO in the exhaust of individual vehicles. Additionally, the CO2 isotopes, and the CO:CO2, CH4:CO2 and H2:CO gas ratios were measured. This was done under idling and revving conditions, and for three vehicles in a full driving cycle on a testbench. The spread in the results, even for a single vehicle, was large: for δ13 C in CO ∼ -60 to 0‰, for δ18 O in CO ∼ +10 to +35‰, and for all gas ratios several orders of magnitude. The results show an increase in the spread of isotopic values for CO compared to previous studies, suggesting that increasing complexity of emission control in vehicles might be reflected in the isotopic composition. When including all samples, we find a weighted mean for the δ13 C and δ18 O in CO of -28.7 ± 0.5‰ and +24.8 ± 0.3‰ respectively. This result is dominated by cold petrol vehicles. Diesel vehicles behaved as a distinct group, with CO enriched in 13C and depleted in 18O, compared to petrol vehicles. For the H2:CO ratio of all vehicles, we found a value of 0.71 ± 0.31 ppb:ppb. The CO:CO2 ratio, with a mean of 19.4 ± 6.8 ppb:ppm, and the CH4:CO2 ratio, with a mean of 0.26 ± 0.05 ppb:ppm, are both higher than recent literature indicates. This is likely because our sampling distribution was biased towards cold vehicles, and therefore towards higher emission situations. The CH4:CO2 ratio was found to behave similarly to the CO:CO2 ratio, suggesting that the processes affecting CO and CH4 are similar. The δ13 C values in CO2 were close to the expected δ13 C in fuel, with no significant difference between petrol and diesel vehicles. The δ18 O values in CO2 for petrol vehicles covered a range of 20-35‰, similar to the δ18 O of CO. The δ18 O values in CO2 for diesel vehicles were close to the δ18 O in atmospheric oxygen. A set of polluted atmospheric samples, taken near a highway and inside parking garages, showed an isotopic signature of CO and a H2:CO ratio that were

  20. Salt Composition Derived from Veazey Composition by Thermodynamic Modeling and Predicted Composition of Drum Contents

    Energy Technology Data Exchange (ETDEWEB)

    Weisbrod, Kirk Ryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Veirs, Douglas Kirk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Funk, David John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Clark, David Lewis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    This report describes the derivation of the salt composition from the Veazey salt stream analysis. It also provides an estimate of the proportions of the kitty litter, nitrate salt and neutralizer that was contained in drum 68660. While the actinide content of waste streams was judiciously followed in the 1980s in TA-55, no record of the salt composition could be found. Consequently, a salt waste stream produced from 1992 to 1994 and reported by Gerry Veazey provided the basis for this study. While chemical analysis of the waste stream was highly variable, an average analysis provided input to the Stream Analyzer software to calculate a composition for a concentrated solid nitrate salt and liquid waste stream. The calculation predicted the gas / condensed phase compositions as well as solid salt / saturated liquid compositions. The derived composition provides an estimate of the nitrate feedstream to WIPP for which kinetic measurements can be made. The ratio of salt to Swheat in drum 68660 contents was estimated through an overall mass balance on the parent and sibling drums. The RTR video provided independent confirmation concerning the volume of the mixture. The solid salt layer contains the majority of the salt at a ratio with Swheat that potentially could become exothermic.

  1. Seasonal variation in the distribution and isotopic composition of phytoplankton in an amazon floodplain lake, Brazil

    International Nuclear Information System (INIS)

    Caraballo, Pedro; Forsberg, Bruce R; Leite, Rosseval G

    2014-01-01

    To evaluate the seasonal variation and isotopic composition of phytoplankton, water samples were collected monthly between October 2007 and November 2008 in Lake Catalao, a floodplain lake at the confluence between rivers Negro and Amazon. Analyses of total chlorophyll concentration and δ 1 3C and δ 1 5N isotopic abundances were made from particulate size fractions of 30-60, 10-30 and <10 μm in the littoral, pelagic, and floating meadows regions. Chlorophyll concentration was found to be inversely associated to lake depth, and high concentrations of chlorophyll in the floating meadows zone were significant. The fraction <10 μm was the most abundant representing in average more than 40% of the particulate matter. The δ3 13C values were relatively constant during the study (-25.1% -34.0%), whereas the δ 1 5N values showed strong variability (15.6% 2.4%), which has been attributed to the resuspension of sediments during mixing of the water column. Mixing associated to the sudden drop in temperature during the rising water period was an important event in the trophic and isotopic dynamics of the lake. Variations in chlorophyll content were generally associated with the dilution process, in which concentration was inversely correlated to the water level, whereas abundance was directly correlated to the water level.

  2. Isotopic and Elemental Composition of Roasted Coffee as a Guide to Authenticity and Origin.

    Science.gov (United States)

    Carter, James F; Yates, Hans S A; Tinggi, Ujang

    2015-06-24

    This study presents the stable isotopic and elemental compositions of single-origin, roasted coffees available to retail consumers. The δ(13)C, δ(15)N, and δ(18)O compositions were in agreement with those previously reported for green coffee beans. The δ(15)N composition was seen to be related to organic cultivation, reflected in both δ(2)H and δ(18)O compositions. The δ(13)C composition of extracted caffeine differed little from that of the bulk coffee. Stepwise discriminant analysis with jackknife tests, using isotopic and elemental data, provided up to 77% correct classification of regions of production. Samples from Africa and India were readily classified. The wide range in both isotopic and elemental compositions of samples from other regions, specifically Central/South America, resulted in poor discrimination between or within these regions. Simpler X-Y and geo-spatial plots of the isotopic data provided effective visual means to distinguish between coffees from different regions.

  3. Comparative feeding ecology of abyssal and hadal fishes through stomach content and amino acid isotope analysis

    Science.gov (United States)

    Gerringer, M. E.; Popp, B. N.; Linley, T. D.; Jamieson, A. J.; Drazen, J. C.

    2017-03-01

    The snailfishes, family Liparidae (Scorpaeniformes), have found notable success in the hadal zone from 6000-8200 m, comprising the dominant ichthyofauna in at least five trenches worldwide. Little is known about the biology of these deepest-living fishes, nor the factors that drive their success at hadal depths. Using recent collections from the Mariana Trench, Kermadec Trench, and neighboring abyssal plains, this study investigates the potential role of trophic ecology in structuring fish communities at the abyssal-hadal boundary. Stomach contents were analyzed from two species of hadal snailfishes, Notoliparis kermadecensis and a newly-discovered species from the Mariana Trench. Amphipods comprised the majority (Kermadec: 95.2%, Mariana: 97.4% index of relative importance) of stomach contents in both species. Decapod crustaceans, polychaetes (N. kermadecensis only), and remains of carrion (squid and fish) were minor dietary components. Diet analyses of abyssal species (families Macrouridae, Ophidiidae, Zoarcidae) collected from near the trenches and the literature are compared to those of the hadal liparids. Stomachs from abyssal fishes also contained amphipods, however macrourids had a higher trophic plasticity with a greater diversity of prey items, including larger proportions of carrion and fish remains; supporting previous findings. Suction-feeding predatory fishes like hadal liparids may find an advantage to descending into the trench - where amphipods are abundant. More generalist feeders and scavengers relying on carrion, such as macrourids, might not benefit from this nutritional advantage at hadal depths. Compound specific isotope analysis of amino acids was used to estimate trophic level of these species (5.3±0.2 Coryphaenoides armatus, 5.2±0.2 C. yaquinae, 4.6±0.2 Spectrunculus grandis, 4.2±0.2 N. kermadecensis, 4.4±0.2 Mariana snailfish). Source amino acid δ15N values were especially high in hadal liparids (8.0±0.3‰ Kermadec, 6.7±0.2

  4. [Composite editorial contents in French chemical journals].

    Science.gov (United States)

    Dalbin, Sylvie

    2014-01-01

    This study of a corpus of French chemistry journals between 1800 and 2010 shows the relevance of the journal as the primary mode of communication, confirming the results of the general survey presented in this issue. However, a study of their contents is questioning the apparent unity of this phenomenon: the journal appears as a physical medium consisting in a common container including a wide range of information categories transferred over time to digital platforms in development since the end of the 20(th) century.

  5. Containing arsenic-enriched groundwater tracing lead isotopic compositions of common arsenical pesticides in a coastal Maine watershed

    Science.gov (United States)

    Ayuso, Robert A.; Foley, Nora K.; Robinson, Glipin R.; Colvin, A.S.; Lipfert, G.; Reeve, A.S.

    2006-01-01

    Arsenical pesticides and herbicides were extensively used on apple, blueberry, and potato crops in New England during the first half of the twentieth century. Lead arsenate was the most heavily used arsenical pesticide until it was officially banned. Lead arsenate, calcium arsenate, and sodium arsenate have similar Pb isotope compositions: 208Pb207Pb = 2.3839-2.4722, and 206Pb207Pb = 1.1035-1.2010. Other arsenical pesticides such as copper acetoarsenite (Paris green), methyl arsonic acid and methane arsonic acid, as well as arsanilic acid are widely variable in isotope composition. Although a complete understanding of the effects of historical use of arsenical pesticides is not available, initial studies indicate that arsenic and lead concentrations in stream sediments in New England are higher in agricultural areas that intensely used arsenical pesticides than in other areas. The Pb isotope compositions of pesticides partially overlap values of stream sediments from areas with the most extensive agricultural use. The lingering effects of arsenical pesticide use were tested in a detailed geochemical and isotopic study of soil profiles from a watershed containing arsenic-enriched ground water in coastal Maine. Acid-leach compositions of the soils represent lead adsorbed to mineral surfaces or held in soluble minerals (Fe- and Mn-hydroxides, carbonate, and some micaceous minerals), whereas residue compositions likely reflect bedrock compositions. The soil profiles contain labile Pb (acid-leach) showing a moderate range in 206Pb 207Pb (1.1870-1.2069), and 208Pb207Pb (2.4519-2.4876). Isotope values vary as a function of depth: the lowest Pb isotope ratios (e.g.,208Pb206Pb) representing labile lead are in the uppermost soil horizons. Lead contents decrease with depth in the soil profiles. Arsenic contents show no clear trend with depth. A multi-component mixing scheme that included lead from the local parent rock (Penobscot Formation), lead derived from combustion of

  6. Chemical and isotopic compositions of bottled waters sold in Korea: chemical enrichment and isotopic fractionation by desalination.

    Science.gov (United States)

    Kim, Go-Eun; Ryu, Jong-Sik; Shin, Woo-Jin; Bong, Yeon-Sik; Lee, Kwang-Sik; Choi, Man-Sik

    2012-01-15

    A total of 54 Korean bottled waters were investigated to characterize their origins and types using elemental and isotopic composition, as well as to identify elemental and isotopic changes in desalinated marine water that arise due to desalination. The different types of bottled water displayed a wide pH range (3.42 to 7.21). The elemental compositions of still and sparkling waters were quite similar, whereas desalinated marine water was clearly distinguished by its high concentrations of Ca, Mg, B, and Cl. In addition, desalinated marine water had much higher isotope ratios of oxygen and hydrogen (-0.5 and -2‰, respectively) than still and sparkling waters (-8.4 and -57‰). The elemental composition of desalinated marine water was adjusted through post-treatment procedures; in particular, boron was greatly enriched during desalination processes. The carbon isotope compositions of dissolved inorganic carbon (δ(13)C(DIC) values) varied widely according to the origins of the bottled waters (-25.6 to -13.6‰ for still water, -31.2 to -26.7‰ for sparkling water, and -24.1 to -6.3‰ for desalinated marine water). This indicates that carbon isotopes in dissolved inorganic carbon are significantly fractionated by desalination processes and re-modified through post-treatment procedures. The results suggest that combined elemental and stable isotopic tracers are useful for identifying the origin of bottled water, verifying elemental and isotopic modifications during desalination processes, and characterizing various water types of bottled waters. Copyright © 2011 John Wiley & Sons, Ltd.

  7. Tungsten isotope composition of the Acasta Gneiss Complex

    Science.gov (United States)

    Willbold, M.; Mojzsis, S. J.; Chen, H.-W.; Elliott, T.

    2015-06-01

    High-precision tungsten (182W/184W) isotope measurements on well-characterised mafic and felsic samples of the ca. 3960 Ma Acasta Gneiss Complex (AGC; Northwest Territories, Canada) show radiogenic ε182W values between +0.06 to +0.15. Two ca. 3600 Ma felsic samples from this terrane have ε182W ∼ 0 and are the oldest samples so far documented to have a W isotopic composition indistinguishable from that of the modern mantle. The ε182W data are correlated with ε142Nd (Roth et al., 2014) and we attribute this variability to incomplete metamorphic homogenisation of the 3960 Ma protolith with more recent material in a 3370 Ma tectono-thermal event. Notably, the value of the positive ε182W anomalies seen in the 3960 Ma AGC samples that are least affected by metamorphic homogenisation is comparable to that observed in other early Archean rocks (Isua Supracrustal Belt, Greenland; Nuvvuagittuq Supracrustal Belt, Canada) and the late Archean Kostomuksha komatiites (Karelia). This demonstrates a globally constant signature. We infer that the presence of a pre-late veneer mantle represents the most straightforward interpretation of a uniform distribution of ε182W ∼ + 0.15 value in Archean rocks of different ages. We show that such a notion is compatible with independent constraints from highly siderophile element abundances in mafic and ultra-mafic Archean mantle-derived rocks. The absence of anomalous ε182W and ε142Nd so far measured in samples younger than ca. 2800 Ma suggests progressive convective homogenisation of silicate reservoirs. The downward mixing of an upper mantle rich in late-delivered meteoritic material might account for these combined observations.

  8. Determination of Pu isotopic composition and 241Am by high resolution gamma spectrometry on solid samples

    International Nuclear Information System (INIS)

    Sarkar, Arnab; Paul, Sumana; Aggarwal, Suresh K.; Tomar, Bhupendra S.

    2011-08-01

    The present report gives a detailed account of the development of non-destructive assay technique using high resolution gamma-ray spectrometry (HRGS) for determination of plutonium (Pu) isotopic composition and the 241 Am content in solid Pu samples. Energy range 120-420 keV was used in this study. The methodology involves in situ relative efficiency calibration during the measurement process itself, to reduce the errors and increase the reliability of the method. Twenty solid Pu samples of power reactor and research reactor grade were analyzed by this method and the results were compared with those obtained by thermal ionization mass spectrometry. The accuracy of the final results depends strongly upon the accuracy of the available nuclear data (decay constant, gamma abundance etc.). MATLAB based programme was written to perform the analysis. A counting time of 4 hour was chosen for achieving good statistics on the results for samples having 100-200 mg of Pu. The attainable accuracy is found to be 0.5-1% for the fissile isotopes ( 239 Pu + 241 Pu) and 5-10% for 241 Am content. (author)

  9. Seasonality of Oxygen isotope composition in cow (Bos taurus) hair and its model interpretation

    Science.gov (United States)

    Chen, Guo; Schnyder, Hans; Auerswald, Karl

    2017-04-01

    Oxygen isotopes in animal and human tissues are expected to be good recorders of geographical origin and migration histories based on the isotopic relationship between hair oxygen and annual precipitation and the well-known spatial pattern of oxygen isotope composition in meteoric water. However, seasonal variation of oxygen isotope composition may diminish the origin information in the tissues. Here the seasonality of oxygen isotope composition in tail hair was investigated in a domestic suckler cow (Bos taurus) that underwent different ambient conditions, physiological states, and keeping and feeding strategies during five years. A detailed mechanistic model involving in ambient conditions, soil properties and animal physiology was built to explain this variation. The measured oxygen isotope composition in hair was significantly related (panalysis. Modelling suggested that this relation was only partly derived from the direct influence of feed moisture. Ambient conditions (temperature, moisture) did not only influence the isotopic signal of precipitation but also affected the animal itself (drinking water demand, transcutaneous vapor etc.). The clear temporal variation thus resulted from complex interactions with multiple influences. The twofold influence of ambient conditions via the feed and via the animal itself is advantageous for tracing the geographic origin because the oxygen isotope composition is then less influenced by variations in moisture uptake; however, it is unfavorable for indicating the production system, e.g. to distinguish between milk produced from fresh grass or from silage.

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

    Science.gov (United States)

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

    2018-04-01

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

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

    Science.gov (United States)

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

    2017-07-01

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

  12. The isotopic compositions database system on spent fuels in light water reactors (SFCOMPO)

    International Nuclear Information System (INIS)

    Kurosawa, Masayoshi; Naito, Yoshitaka; Sakamoto, Hiroki; Kaneko, Toshiyuki.

    1997-02-01

    In the framework of the activity of the nuclide production evaluation WG in the Sigma Committee in Japan, we have been collecting the assay data on the isotopic composition of LWR spent fuels. Those data are required for verification of accuracy of the burnup calculation codes. To supply worldwide users with these types of data, the isotopic composition database system SFCOMPO was constructed on an IBM PC-AT (compatible computers). The SFCOMPO includes the isotopic composition data from 10 LWRs (the 6 PWRs and 4 BWRs) and several sets of axial burnup profiles of spent fuel rods. (author)

  13. Development and validation of a method to determine the boron isotopic composition of crop plants.

    Science.gov (United States)

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

    2011-04-01

    We present a comprehensive chemical and mass spectrometric method to determine boron isotopic compositions of plant tissue. The method including dry ashing, a three-step ion chromatographic boron-matrix separation, and (11)B/(10)B isotope ratio determinations using the Cs(2)BO(2)(+) graphite technique has been validated using certified reference and quality control materials. The developed method is capable to determine δ(11)B values in plant tissue down to boron concentrations of 1 mg/kg with an expanded uncertainty of ≤1.7‰ (k = 2). The determined δ(11)B values reveal an enormous isotopic range of boron in plant tissues covering three-quarters of the natural terrestrial occurring variation in the boron isotopic composition. As the local environment and anthropogenic activity mainly control the boron intake of plants, the boron isotopic composition of plants can be used for food provenance studies.

  14. Near Surface CO2 Triple Oxygen Isotope Composition

    Directory of Open Access Journals (Sweden)

    Sasadhar Mahata

    2016-02-01

    Full Text Available The isotopic composition of carbon dioxide in the atmosphere is a powerful tool for constraining its sources and sinks. In particular, the 17O oxygen anomaly [Δ17O = 1000 × ln(1 + δ17O/1000 - 0.516 × 1000 × ln(1 + δ18O/1000], with a value > 0.5‰ produced in the middle atmosphere, provides an ideal tool for probing the exchange of carbon dioxide between the biosphere/hydrosphere and atmosphere. The biosphere/hydrosphere and anthropogenic emissions give values ≤ 0.3‰. Therefore, any anomaly in near surface CO2 would reflect the balance between stratospheric input and exchange with the aforementioned surface sources. We have analyzed Δ17O values of CO2 separated from air samples collected in Taipei, Taiwan, located in the western Pacific region. The obtained mean anomaly is 0.42 ± 0.14‰ (1-σ standard deviation, in good agreement with model prediction and a published decadal record. Apart from typically used δ13C and δ18O values, the Δ17O value could provide an additional tracer for constraining the carbon cycle.

  15. In situ observations of the isotopic composition of methane at the Cabauw tall tower site

    NARCIS (Netherlands)

    Röckmann, Thomas; Eyer, Simon; Van Der Veen, Carina; Popa, Maria E.; Tuzson, Béla; Monteil, Guillaume; Houweling, Sander; Harris, Eliza; Brunner, Dominik; Fischer, Hubertus; Zazzeri, Giulia; Lowry, David; Nisbet, Euan G.; Brand, Willi A.; Necki, Jaroslav M.; Emmenegger, Lukas; Mohn, Joachim

    2016-01-01

    High-precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in

  16. Isotopic composition of water in the environment. Water on the surface on the earth

    International Nuclear Information System (INIS)

    Nief, Guy; Merlivat, Liliane

    1976-01-01

    The isotopic composition of water is influenced by the physico-chemical transformations occuring during water cycle. These isotopic variations supply much information on various meteorological or hydrological phenomena. It is shown how the study of these variations can help towards the understanding and interpretation of the basic phenomena which generate them [fr

  17. Isotopic composition of rainfall and runoff in a small arid basin with implications for deep percolation

    International Nuclear Information System (INIS)

    Dody, A.

    1995-08-01

    The aim of this work was to characterize the isotopic composition of potential recharge in an arid rocky watershed. Unique field observations were obtained from an arid watershed in the Negev Highlands, Israel, through utilization of the dynamic variations in the isotopic composition of rainfall and runoff. The hydrological system's inputs are rainfall and its isotopic composition. Rainfall and runoff were sampled in eight storms. High variability in the isotopic composition of rainfall was observed during any single rainstorm. The isotopic distribution in the runoff at the outlet of the basin appeared often not to be correlated to the isotopic patterns of the associated rain storm. A new mathematical model was developed to describe these physical processes. The model called A Double-Component Kinematic Wave Flow and Transport Approach, was designated to assess the dynamic isotopic distribution in arid rain storms and runoff. This model simulates the transport of rainfall into overland flow and runoff in an arid rocky watershed with uniformly distributed shallow depression storage. A numerical solution for the problem was developed, to estimate the depression storage parameters. The model also reflects the isotopic memory effect due to the depression storage between sequential rain showers. A good agreement between the observed and computed hydrograph and the change of the δ 18O values in runoff in time confirms the validity of the model. (author) 138 figs., 125 refs

  18. Use of Isotopic Composition Data to Improve Reactor Calculational Techniques,

    Science.gov (United States)

    calculational code processes to real data. By applying isotopic correlation techniques to this source of data and to data from burnup calculations , it...Before the availability of isotopic data from chemical reprocessing of spent nuclear fuels, burnup code normalization was done using data from small... burnup samples. Chemical reprocessing plant isotopic data are in additional source of burnup data reliably measured to permit normalization of

  19. A numerical cloud model to interpret the isotope content of hailstones

    International Nuclear Information System (INIS)

    Jouzel, J.; Brichet, N.; Thalmann, B.; Federer, B.

    1980-07-01

    Measurements of the isotope content of hailstones are frequently used to deduce their trajectories and updraft speeds within severe storms. The interpretation was made in the past on the basis of an adiabatic equilibrium model in which the stones grew exclusively by interaction with droplets and vapor. Using the 1D steady-state model of Hirsch with parametrized cloud physics these unrealistic assumptions were dropped and the effects of interactions between droplets, drops, ice crystals and graupel on the concentrations of stable isotopes in hydrometeors were taken into account. The construction of the model is briefly discussed. The resulting height profiles of D and O 18 in hailstones deviate substantially from the equilibrium case, rendering most earlier trajectory calculations invalid. It is also seen that in the lower cloud layers the ice of the stones is richer due to relaxation effects, but at higher cloud layers (T(a) 0 C) the ice is much poorer in isotopes. This yields a broader spread of the isotope values in the interval 0>T(a)>-35 0 C or alternatively, it means that hailstones with a very large range of measured isotope concentrations grow in a smaller and therefore more realistic temperature interval. The use of the model in practice will be demonstrated

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

    Science.gov (United States)

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

    2011-12-01

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

  1. Monitoring the water vapor isotopic composition in the temperate North Atlantic

    Science.gov (United States)

    Sveinbjörnsdottir, Arny E.; Steen-Larsen, Hans Christian; Jonsson, Thorsteinn; Johnsen, Sigfus J.

    2013-04-01

    Water stable isotopes have during many decades been used as climate proxies and indicators for variations in the hydrological cycle. However we are to a great extent still using simple empirical relationships without any deeper theoretical understanding. In order to properly relate changes in the climate and hydrological cycle to changes in the observed stable water isotopic signal we must understand the underlying physical processes. Furthermore it is a challenge for General Climate Models to adequately represent the isotopes in the hydrological cycle because of lack of in-situ measurements of the atmospheric water-vapor composition in the source regions. During the fall of 2010 we installed an autonomous water vapor spectroscopy laser (from Los Gatos Research) in a lighthouse on the South Coast of Iceland (63.83 N 21.47W) with the plan to be operational for several years. The purpose of this installation was through monitoring of the water vapor isotopic composition to understand the physical processes governing the isotopic composition of the water vapor evaporated from the ocean as well as the processes of mixing between the free troposphere and marine boundary layer. Because of the remoteness of the monitoring site and simple topography we are able to isolate the 'fingerprint' on the isotopic signal in the water vapor from respectively the ocean and the interior highland leading to a near perfect case-study area. Using back-trajectories we find a strong influence of the origin of the air masses on the measured isotopic composition. The mixing of the marine-boundary layer is found to strongly influence the measured isotopic composition. The second order isotopic parameter, d-excess, is contrary to theory and previous observations found not to depend on the relative humidity. However we do find a good correlation between the d-excess and the measured isotopic composition. We speculate that the lack of correlation between d-excess and relative humidity can be

  2. Carbon-13 kinetic isotope effects in the decarbonylation of lactic acid of natural isotopic composition in phosphoric acid medium

    International Nuclear Information System (INIS)

    Zielinski, M.; Czarnota, G.; Papiernik-Zielinska, H.; Kasprzyk, G.; Gumolka, L.; Staedter, W.

    1993-01-01

    The 13 C kinetic isotope effect fractionation in the decarbonylation of lactic acid (LA) of natural isotopic composition by concentrated phosphoric acids (PA) and by 85% H 3 PO 4 has been studied in the temperature interval of 60-150 deg C. The values of the 13 C (1) isotope effects in the decarbonylation of lactic acid in 100% H 3 PO 4 , in pyrophosphoric acid and in more concentrated phosphoric acids are intermediate between the values calculated assuming that the C (1)- OH bond is broken in the rate-controlling step of dehydration and those calculated for rupture of the carbon-carbon bond in the transition state. In the temperature interval of 90-130 deg C the experimental 13 C fractionation factors determined in concentrated PA approach quite closely the 13 C fractionation corresponding to C (2)- C (1) bond scission. The 13 C (1) kinetic isotope effects in the decarbonylation of LA in 85% orthophosphoric acid in the temperature range of 110-150 deg C coincide with the 13 C isotope effects calculated assuming that the frequency corresponding to the C (1) -OH vibration is lost in the transition state of decarbonylation. A change of the mechanism of decarbonylation of LA in going from concentrated PA medium to 85% H 3 PO 4 has been suggested. A possible secondary 18 O and a primary 18 O kinetic isotope effect in decarbonylation of lactic acid in phosphoric acids media have been discussed, too. (author) 21 refs.; 3 tabs

  3. Selenium speciation and isotope composition in 77Se-enriched yeast using gradient elution HPLC separation and ICP-dynamic reaction cell-MS

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Sloth, Jens Jørgen; Hansen, M.

    2003-01-01

    A batch of Se-77-labelled and enriched yeast was characterised with regard to isotopic composition and content of selenium species for later use in a human absorption study based on the method of enriched stable isotopes. The abundance of the six stable selenium isotopes was determined by ICP- MS...... equipped with a dynamic reaction cell (DRC). The results showed that the Se-77 isotope was enriched to 98.5 atom-%, whereas the remaining selenium was present as the other five isotopes at low abundance. The low-molecular Se-77 containing species, which were biosynthesised by the yeast during fermentation...... using the enriched Se-77-selenite as substrate, were released by enzymatic hydrolysis using (I), a beta-glucosidase followed by a protease mixture, and (II), a commercial protease preparation. For selenium speciation the chromatographic selectivity of the cation exchange HPLC system was adjusted...

  4. Structure and content of competitive group compositions in sports aerobics

    Directory of Open Access Journals (Sweden)

    Tetiana Moshenska

    2017-02-01

    Full Text Available Purpose: to make the analysis of modern competitive group compositions in sports aerobics. Material & Methods: pedagogical, sociological and methods of mathematical statistics were used. 10 coaches took part in the experimental part; analysis of protocols and video records of competitions of the aged category of children of 9–11 years old, who perform in the nomination of triplets and quintuples (group exercises, is carried out. Results: the content of competitive compositions and the allocated indicators are studied which defined it. Conclusions: the basic structural elements, which characterize competitive compositions, are allocated. Their components, quantity and time of performance are defined. It is established that variety of aerobic contents, spaces, and means of registration, musical compliance and logicality of creation of the whole competitive composition at high quality of performance characterizes teams – winners.

  5. The use of stable isotope compositions of selected elements in food origin control

    International Nuclear Information System (INIS)

    Wierzchnicki, R.

    2002-01-01

    Stable isotope ratios have been used widely for authentication of foodstuffs especially for detection of added water and sugar in fruit juices and wines. Hydrogen and oxygen composition are particularly interesting probes for geographical origin and authenticity identification. Carbon and nitrogen composition of fruits contains the finger-print of their metabolism and growing condition. Exemplary data are presented which demonstrated the usefulness of the Isotope Ratio Mass Spectrometry (IRMS) methods for authenticating wines and fruits (juice and pulp). (author)

  6. Improvements to SFCOMPO - a database on isotopic composition of spent nuclear fuel

    International Nuclear Information System (INIS)

    Suyama, Kenya; Nouri, Ali; Mochizuki, Hiroki; Nomura, Yasushi

    2003-01-01

    Isotopic composition is one of the most relevant data to be used in the calculation of burnup of irradiated nuclear fuel. Since autumn 2002, the Organisation for Economic Co-operation and Development/Nuclear Energy Agency (OECD/NEA) has operated a database of isotopic composition - SFCOMPO, initially developed in Japan Atomic Energy Research Institute. This paper describes the latest version of SFCOMPO and the future development plan in OECD/NEA. (author)

  7. Spatiotemporal variation of stable isotopic composition in precipitation

    DEFF Research Database (Denmark)

    Müller, Sascha; Stumpp, Christine; Sørensen, Jens Havskov

    2017-01-01

    gradient and predominant westerly winds. Data showed the local meteoric water line for this region is expressed by the equation δ2H = 7.4δ18O + 5.4‰. A significant trend correlating enriched isotopic values to humidities around 70% during dry season and more depleted isotopic values to humidities around 90...

  8. Carbon isotopic composition of fossil leaves from the Early ...

    Indian Academy of Sciences (India)

    Keywords. Carbon isotopes; plant fossil; Cretaceous; Kachchh; pCO2. J. Earth Syst. Sci. 120, No. 4, August 2011, pp. 703–711 c Indian Academy of Sciences. 703 ... and Banerji 1984). Though in this context it may be mentioned that the isotopic analysis of benthic foraminifera from Kachchh helped to quantify the.

  9. Changes in Oxygen Isotopes Composition of Precipitation over Tibetan Plateau during Cenozoic

    Science.gov (United States)

    Botsyun, S.; Sepulchre, P.; Donnadieu, Y.; Risi, C. M.; Fluteau, F.

    2014-12-01

    Despite the increasing role of the stable oxygen isotopes measurements for reconstructing mountains belts paleoelevation, some issues remain that lead to a large uncertainty in paleoelevation estimationes. Among them, the use of modern isotopic lapse rate with no account of climate change linked to lower topography can lead to misinterpretation of uplift rates. In this study, we use the atmospheric general circulation model LMDZ-iso to simulate changes in isotopic composition of precipitation due to uplift of the Himalayas and Tibetan plateau. Various scenarios of TP growth have been applied together with Paleocene, Eocene, Oligocene and Miocene boundary conditions. Our simulations allow us to estimate the magnitude of precipitation, temperature and wind field changes related to the spatial and temporal evolution of the Tibetan Plateau and Himalayas. Such changes affected the isotopic composition of precipitation during the Cenozoic.We investigate the impact of these changes on the isotopic lapse rate and the implications for paleoelevation estimates.

  10. Morphology, molecular structure, and stable carbon isotopic composition of black carbon (BC) in urban topsoils.

    Science.gov (United States)

    Zong, Yutong; Xiao, Qing; Lu, Shenggao

    2018-02-01

    Urban soils contain significant amounts of black carbon (BC) from biomass and fossil fuel combustion and regard to be a pool of BC. BC in urban soils has multiple effects on environmental processes in urban system, such as global climate change, air quality, and public health. Urban topsoil samples (0-10 cm) were collected from Anshan, Liaoning Province, northeast China, which is one of the most important old steel industrial bases in China. The BC in urban topsoils was extracted using the density method. Their chemical composition, morphology, molecular structure, and stable carbon isotopic composition were examined using elemental analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and stable carbon isotope (δ 13 C). Elemental analysis shows that carbon content in the BC of studied soils ranged from 64.5 to 78.4%, with the average more than 70%. The O/C atomic ratio of BC is on average 0.18. The BC particle displays different morphology, including porous spherical, irregular porous fragmentary, and blocky shapes. The porous spherical BC particles has atomic molar O/C ratio determined by SEM-EDS ranging from 0.04 to 0.37. XRD indicates that BC exists in mainly combining with mineral phases hematite (Fe 2 O 3 ), kaolinite (Al 2 Si 2 O 5 (OH) 4 ), quartz (SiO 2 ), and calcite (CaCO 3 ). The FTIR spectra of BC particles show major bands at approximately 3400 cm -1 (O-H), 2920 cm -1 (C = H), 1600 cm -1 (C = C), 1230 cm -1 (C = O), and 1070 cm -1 (C = O). The stable carbon isotope (δ 13 C) of BC ranges from -24.48 to -23.18‰ with the average of -23.79 ± 0.39‰. The concentration of BC in the industrial area is significantly (p fuel combustion. Results indicated that a combination of atomic O/C ratio, porous structure, and stable carbon isotopic (δ 13 C) of BC could reflect effectively the origin of BC

  11. Variations in isotopic compositions of chlorine in evaporation-controlled salt lake brines of Qaidam Basin, China

    Digital Repository Service at National Institute of Oceanography (India)

    Xiao, Ying-kai; Liu, Wei-guo; Zhou, Y.M.; Wang, Yun-hui; Shirodkar, P.V.

    The variations in the isotopic compositions of chlorine in evaporation-controlled saline lake brines were determined by using an improved procedure for precise measurement of chlorine isotopes based on Cs sub(2) Cl sup(+) ion by thermal ionization...

  12. A paired apatite and calcite clumped isotope thermometry approach to estimating Cambro-Ordovician seawater temperatures and isotopic composition

    Science.gov (United States)

    Bergmann, Kristin D.; Finnegan, Seth; Creel, Roger; Eiler, John M.; Hughes, Nigel C.; Popov, Leonid E.; Fischer, Woodward W.

    2018-03-01

    The secular increase in δ18O values of both calcitic and phosphatic marine fossils through early Phanerozoic time suggests either that (1) early Paleozoic surface temperatures were high, in excess of 40 °C (tropical MAT), (2) the δ18O value of seawater has increased by 7-8‰ VSMOW through Paleozoic time, or (3) diagenesis has altered secular trends in early Paleozoic samples. Carbonate clumped isotope analysis, in combination with petrographic and elemental analysis, can deconvolve fluid composition from temperature effects and therefore determine which of these hypotheses best explain the secular δ18O increase. Clumped isotope measurements of a suite of calcitic and phosphatic marine fossils from late Cambrian- to Middle-late Ordovician-aged strata-the first paired fossil study of its kind-document tropical sea surface temperatures near modern temperatures (26-38 °C) and seawater oxygen isotope ratios similar to today's ratios.

  13. Magnesium and Titanium Isotopic Compositions of an Unusual Hibonite-Perovskite Refractory Inclusion from Allende: It Is Fun

    Science.gov (United States)

    Liu, M.-C.; Keller, L. P.; McKeegan, K. D.

    2016-01-01

    of (sup 26) Al. Delta (sup 25) Mg (mass-dependent fractionation) in hibonite is approximately -5 per mille per atomic mass unit relative to Madagascar hibonite, but is not well constrained for perovskite due to very large uncertainties owing to extremely low Mg contents. Similar to Mg isotopes, SHAL hibonite and perovskite show essentially the same Ti isotopic compositions, with anomalies in (sup 50) Ti of approximately 14 per mille, but the former shows greater Ti isotope fractionation than the latter (2.5 per mille per atomic mass unit versus 0 per mille). Discussion and Conclusions: The Al-Mg and Ti isotopic compositions of SHAL hibonite are consistent with those of HAL, suggesting that SHAL hibonite is a FUN inclusion and likely formed prior to homogenization of (sup 26) Al and Ti isotope variations in the solar nebula. However, the formation mechanisms for SHAL and HAL differ, given the differences in the REE patterns and degrees of oxygen mass-dependent fractionation. The Group-II to Group-III like REE patterns, the Yb depletions, and negative delta (sup 25) Mg observed in SHAL hibonite are all consistent with condensation of the hibonite precursor in a reducing environment.. The lack of large Ce depletions in SHAL hibonite implies that distillation processes that fractionated hibonite's oxygen isotopes must have taken place under a reducing condition, but the extent to which SHAL hibonite was distilled appears to be less than HAL because of the smaller degree of oxygen mass-dependent fractionation. The perovskite shares essentially the same Ti and Mg isotopic compositions as hibonite and probably formed in the same reservoir.. The ultrarefractory REE pattern seen in perovskite likely resulted from gas-solid fractionation which depleted HREEs in this reservoir. This process also explains why SHAL hibonite is generally depleted in HREEs relative to LREEs.

  14. Temporal variation in isotopic composition and diet of Weddell seals in the western Ross Sea

    Science.gov (United States)

    Goetz, Kimberly T.; Burns, Jennifer M.; Hückstӓdt, Luis A.; Shero, Michelle R.; Costa, Daniel P.

    2017-06-01

    Weddell seals (Leptonychotes weddellii) are important predators in the Antarctic marine ecosystem, yet little is known about their diet. Previous studies have used scat and stomach content analyses to examine Weddell seal diet, however, these methods are biased towards prey with indigestible hard parts. To provide a more complete picture of their diet, we analyzed the stable isotope composition (δ13C and δ15N values) of red blood cells (RBC, n=96, representing a time scale of weeks to months) and vibrissae (n=45, representing months to a year) collected over a three year period (2010-2012). Our objectives were to (1) examine isotopic variation in relation to Weddell seal mass, sex, season, location, percent lipid, and age, and (2) quantify the contribution of prey items to overall diet. Body mass was a significant predictor of δ13C and δ15N values for both tissues, though the strength and direction of the relationship varied by year. The prey group consisting of Pleurogramma antarcticum and Trematomus newnesi was found to be an important dietary component, but its proportional contribution to Weddell seal diet varied with the timeframe represented by each tissue type [median RBC (range): 59.2% (40.2-8 1.1%); median mean vibrissae (range): 69.3% (43.9-89.6%)]. Results from mixing models ran for each seal indicate individual variation in diet. Overall, this study presents novel information on the isotopic variation and diet of Weddell seals over two time scales and provides insight into the feeding ecology of an important Antarctic predator.

  15. Characterizing the origins of bottled water on the South Korean market using chemical and isotopic compositions

    International Nuclear Information System (INIS)

    Bong, Yeon-Sik; Ryu, Jong-Sik; Lee, Kwang-Sik

    2009-01-01

    We analyzed the major elements and stable isotopes of oxygen, hydrogen, and carbon (dissolved inorganic carbon: DIC) in various types of bottled water (domestic and foreign) commercially available in South Korea to classify the water types and to identify their origins. Only marine waters and some sparkling waters could be discriminated by their physicochemical compositions. Oxygen and hydrogen isotopes made marine waters more distinguishable from other water types. The determination of the carbon isotope composition of DIC was clearly useful for distinguishing between naturally and artificially sparkling waters. In addition, statistical analysis also appeared to aid in the discrimination of bottled water types. Our results indicate that a method that combines chemical and stable isotope composition analysis with statistical analysis is the most useful for discriminating water types and characterizing the origins of bottled water

  16. Carcass properties, chemical content and fatty acid composition of ...

    African Journals Online (AJOL)

    The aim of this study was to examine carcass properties and variability in chemical content and fatty acid composition in the musculus longissimus lumborum et thoracis (MLLT) of different genotypes of pigs. Of 36 male castrated animals used in the trial, 24 were from two strains of Mangalitsa pigs (12 Swallow - bellied ...

  17. Studies of heavy metal contents and microbial composition of ...

    African Journals Online (AJOL)

    This study investigated the heavy metal content and microbial composition of rhizosphere of Panicum maximum obtained from some auto mechanic workshops in Benin City, Nigeria. The grass was uprooted and soil sample was taken from its rhizosphere. The sample were labeled appropriately and immediately transported ...

  18. Variations in the mineral composition and heavy metals content of ...

    African Journals Online (AJOL)

    Babayemi

    The parts of Moringa oleifera were assessed for mineral composition and some heavy metal contents in this study, which included Ca, Mg, K, Na, Mn, Fe, Zn, Co, Se, Pb and Cd. Parts of the plant were obtained from Badagry in Lagos State, Nigeria. The samples were digested with HNO3 and analysed for the mineral ...

  19. Seed oil content and fatty acid composition of annual halophyte ...

    African Journals Online (AJOL)

    Suaeda acuminata produces two morphologically distinct types of seeds on the same plant. This study was conducted to compare oil content and fatty acid composition of the two seed morphs. Though oil characteristics between dimorphic seeds showed statistically significant difference, these differences were relatively ...

  20. Proximate composition and mineral content in different, types of ...

    African Journals Online (AJOL)

    Six types of traditional togwa (a traditional fermented gruel prepared from a mixture of malted and unmalted cereal grains), six simulated togwa and their ingredients were analysed for proximate composition, energy and mineral contents. The cereals used were maize (Zea mays), finger millet (Eleusine coracana) and ...

  1. Alteration of the Carbon and Nitrogen Isotopic Composition in the Martian Surface Rocks Due to Cosmic Ray Exposure

    Science.gov (United States)

    Pavlov, A. A.; Pavlov, A. K.; Ostryakov, V. M.; Vasilyev, G. I.; Mahaffy, P.; Steele, A.

    2014-01-01

    C-13/C-12 and N-15/N-14 isotopic ratios are pivotal for our understanding of the Martian carbon cycle, history of the Martian atmospheric escape, and origin of the organic compounds on Mars. Here we demonstrate that the carbon and nitrogen isotopic composition of the surface rocks on Mars can be significantly altered by the continuous exposure of Martian surface to cosmic rays. Cosmic rays can effectively produce C-13 and N-15 isotopes via spallation nuclear reactions on oxygen atoms in various Martian rocks. We calculate that in the top meter of the Martian rocks, the rates of production of both C-13 and N-15 due to galactic cosmic rays (GCRs) exposure can vary within 1.5-6 atoms/cm3/s depending on rocks' depth and chemical composition. We also find that the average solar cosmic rays can produce carbon and nitrogen isotopes at a rate comparable to GCRs in the top 5-10 cm of the Martian rocks. We demonstrate that if the total carbon content in a surface Martian rock is <10 ppm, then the "light," potentially "biological" C-13/C-12 ratio would be effectively erased by cosmic rays over 3.5 billion years of exposure. We found that for the rocks with relatively short exposure ages (e.g., 100 million years), cosmogenic changes in N-15/N-14 ratio are still very significant. We also show that a short exposure to cosmic rays of Allan Hills 84001 while on Mars can explain its high-temperature heavy nitrogen isotopic composition (N-15/N-14). Applications to Martian meteorites and the current Mars Science Laboratory mission are discussed.

  2. Iron isotopic composition of blood serum in anemia of chronic kidney disease.

    Science.gov (United States)

    Anoshkina, Yulia; Costas-Rodríguez, Marta; Speeckaert, Marijn; Van Biesen, Wim; Delanghe, Joris; Vanhaecke, Frank

    2017-05-24

    Chronic kidney disease (CKD) is a general term for disorders that affect the structure and function of the kidneys. Iron deficiency (ID) and anemia occur in the vast majority of CKD patients, most of whom are elderly. However, establishing the cause of anemia in CKD, and therefore making an informed decision concerning the corresponding therapeutic treatment, is still a challenge. High-precision Fe isotopic analysis of blood serum samples of CKD patients with and without ID/anemia was performed via multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) for such a purpose. Patients with CKD and/or iron disorders showed a heavier serum Fe isotopic composition than controls. Many clinical parameters used for the diagnosis and follow-up of anemia correlated significantly with the serum Fe isotopic composition. In contrast, no relation was observed between the serum Fe isotopic composition and the estimated glomerular filtration rate as a measure of kidney function. Among the CKD patients, the serum Fe isotopic composition was substantially heavier in the occurrence of ID anemia, while erythropoietin-related anemia did not exert this effect. The Fe isotopic composition can thus be useful for distinguishing these different types of anemias in CKD patients, i.e. ID anemia vs. erythropoietin-related anemia.

  3. Multivariate statistical analysis of the hydrogeochemical and isotopic composition of the groundwater resources in northeastern Peloponnesus (Greece).

    Science.gov (United States)

    Matiatos, Ioannis; Alexopoulos, Apostolos; Godelitsas, Athanasios

    2014-04-01

    The present study involves an integration of the hydrogeological, hydrochemical and isotopic (both stable and radiogenic) data of the groundwater samples taken from aquifers occurring in the region of northeastern Peloponnesus. Special emphasis has been given to health-related ions and isotopes in relation to the WHO and USEPA guidelines, to highlight the concentrations of compounds (e.g., As and Ba) exceeding the drinking water thresholds. Multivariate statistical analyses, i.e. two principal component analyses (PCA) and one discriminant analysis (DA), combined with conventional hydrochemical methodologies, were applied, with the aim to interpret the spatial variations in the groundwater quality and to identify the main hydrogeochemical factors and human activities responsible for the high ion concentrations and isotopic content in the groundwater analysed. The first PCA resulted in a three component model, which explained approximately 82% of the total variance of the data sets and enabled the identification of the hydrogeological processes responsible for the isotopic content i.e., δ(18)Ο, tritium and (222)Rn. The second PCA, involving the trace element presence in the water samples, revealed a four component model, which explained approximately 89% of the total variance of the data sets, giving more insight into the geochemical and anthropogenic controls on the groundwater composition (e.g., water-rock interaction, hydrothermal activity and agricultural activities). Using discriminant analysis, a four parameter (δ(18)O, (Ca+Mg)/(HCO3+SO4), EC and Cl) discriminant function concerning the (222)Rn content was derived, which favoured a classification of the samples according to the concentration of (222)Rn as (222)Rn-safe (11 Bq·L(-1)). The selection of radon builds on the fact that this radiogenic isotope has been generally related to increased health risk when consumed. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Stable isotopic composition of perchlorate and nitrate accumulated in plants: Hydroponic experiments and field data.

    Science.gov (United States)

    Estrada, Nubia Luz; Böhlke, J K; Sturchio, Neil C; Gu, Baohua; Harvey, Greg; Burkey, Kent O; Grantz, David A; McGrath, Margaret T; Anderson, Todd A; Rao, Balaji; Sevanthi, Ritesh; Hatzinger, Paul B; Jackson, W Andrew

    2017-10-01

    Natural perchlorate (ClO 4 - ) in soil and groundwater exhibits a wide range in stable isotopic compositions (δ 37 Cl, δ 18 O, and Δ 17 O), indicating that ClO 4 - may be formed through more than one pathway and/or undergoes post-depositional isotopic alteration. Plants are known to accumulate ClO 4 - , but little is known about their ability to alter its isotopic composition. We examined the potential for plants to alter the isotopic composition of ClO 4 - in hydroponic and field experiments conducted with snap beans (Phaseolus vulgaris L.). In hydroponic studies, anion ratios indicated that ClO 4 - was transported from solutions into plants similarly to NO 3 - but preferentially to Cl - (4-fold). The ClO 4 - isotopic compositions of initial ClO 4 - reagents, final growth solutions, and aqueous extracts from plant tissues were essentially indistinguishable, indicating no significant isotope effects during ClO 4 - uptake or accumulation. The ClO 4 - isotopic composition of field-grown snap beans was also consistent with that of ClO 4 - in varying proportions from irrigation water and precipitation. NO 3 - uptake had little or no effect on NO 3 - isotopic compositions in hydroponic solutions. However, a large fractionation effect with an apparent ε ( 15 N/ 18 O) ratio of 1.05 was observed between NO 3 - in hydroponic solutions and leaf extracts, consistent with partial NO 3 - reduction during assimilation within plant tissue. We also explored the feasibility of evaluating sources of ClO 4 - in commercial produce, as illustrated by spinach, for which the ClO 4 - isotopic composition was similar to that of indigenous natural ClO 4 - . Our results indicate that some types of plants can accumulate and (presumably) release ClO 4 - to soil and groundwater without altering its isotopic characteristics. Concentrations and isotopic compositions of ClO 4 - and NO 3 - in plants may be useful for determining sources of fertilizers and sources of ClO 4 - in their growth

  5. Stable isotopic composition of perchlorate and nitrate accumulated in plants: Hydroponic experiments and field data

    Science.gov (United States)

    Estrada, Nubia Luz; Böhlke, John Karl; Sturchio, Neil C.; Gu, Baohua; Harvey, Greg; Burkey, Kent O.; Grantz, David A.; McGrath, Margaret T.; Anderson, Todd A.; Rao, Balaji; Sevanthi, Ritesh; Hatzinger, Paul B.; Jackson, W. Andrew

    2017-01-01

    Natural perchlorate (ClO4−) in soil and groundwater exhibits a wide range in stable isotopic compositions (δ37Cl, δ18O, and Δ17O), indicating that ClO4− may be formed through more than one pathway and/or undergoes post-depositional isotopic alteration. Plants are known to accumulate ClO4−, but little is known about their ability to alter its isotopic composition. We examined the potential for plants to alter the isotopic composition of ClO4− in hydroponic and field experiments conducted with snap beans (Phaseolus vulgaris L.). In hydroponic studies, anion ratios indicated that ClO4− was transported from solutions into plants similarly to NO3− but preferentially to Cl− (4-fold). The ClO4− isotopic compositions of initial ClO4− reagents, final growth solutions, and aqueous extracts from plant tissues were essentially indistinguishable, indicating no significant isotope effects during ClO4− uptake or accumulation. The ClO4− isotopic composition of field-grown snap beans was also consistent with that of ClO4− in varying proportions from irrigation water and precipitation. NO3− uptake had little or no effect on NO3− isotopic compositions in hydroponic solutions. However, a large fractionation effect with an apparent ε (15N/18O) ratio of 1.05 was observed between NO3− in hydroponic solutions and leaf extracts, consistent with partial NO3− reduction during assimilation within plant tissue. We also explored the feasibility of evaluating sources of ClO4− in commercial produce, as illustrated by spinach, for which the ClO4− isotopic composition was similar to that of indigenous natural ClO4−. Our results indicate that some types of plants can accumulate and (presumably) release ClO4− to soil and groundwater without altering its isotopic characteristics. Concentrations and isotopic compositions of ClO4−and NO3− in plants may be useful for determining sources of fertilizers and sources of ClO4− in their growth environments and

  6. Iron Isotopic Compositions of Troilite (FeS) Inclusions from Iron Meteorites

    Energy Technology Data Exchange (ETDEWEB)

    Cook, David L.; Schönbächler, Maria, E-mail: david.cook@erdw.ethz.ch [Institut für Geochemie und Petrologie, ETH Zürich, Clausiusstrasse 25, 8092 Zürich (Switzerland)

    2017-10-01

    We report non-mass-dependent Fe isotopic data for troilite (FeS) inclusions from 10 iron meteorites, representing both non-magmatic (IAB) and magmatic groups (IIAB, IIIAB, IVA). No resolvable variations are present in the most neutron-rich isotope ({sup 58}Fe), but small deficits (≈−0.1 ε ) in {sup 56}Fe were observed in several inclusions. With the exception of several Ca–Al-rich inclusions in primitive meteorites, these are the first reported non-mass-dependent variations in Fe isotopes for material formed in the early solar system. Nucleosynthetic variations in Ni isotopes were previously reported in these same samples. The effects in Fe isotopes are not correlated with those in Ni, which suggests that the origins of the isotopic variations are decoupled from one another. The {sup 56}Fe deficits may represent incomplete mixing of the precursor dust in the protoplanetary disk. Alternatively, a parent body process (e.g., irradiation by galactic cosmic rays) may have modified the Fe isotopic compositions of some inclusions, which initially had homogeneous Fe isotopic compositions.

  7. Diet of invasive lionfish on hard bottom reefs of the Southeast USA: insights from stomach contents and stable isotopes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Stomach contents and stable isotope analyses were used to determine the diet of lionfish in the warm-temperate hard bottom reef community in theSoutheast US Atlantic...

  8. Evaluation of inorganic particles of composite resins with nanofiller content.

    Science.gov (United States)

    Mota, Eduardo Gonçalves; Hörlle, Lucas; Oshima, Hugo Mitsuo; Hirakata, Luciana Mayumi

    2012-01-01

    The purposes of this study were evaluate by energy dispersed X-ray (EDS) and scanning electron microscopy (SEM) the inorganic particles of three nanofilled composite resins, comparing particles sizes, shape and composition, and the filler weight content by thermogravimetric analyzes (TGA). Three composite resins classified as nanofilled were selected to this study: Esthet-X; Grandio; Filtek Supreme XT. The shade was standardized (A2) for enamel (E) or dentin (D). Ten samples with 20 mg (±10 mg) of each composite resin were submitted to thermogravimetric analyzes (TGA) in order to record the filler weight content (wt%). The amount of inorganic phase ranged from 75.75 to 87 wt%, to Esthet-X (D) and Grandio (D), respectively. The filler composition was analyzed by energy dispersed X-ray (EDS), and the size and shape were evaluated by scanning electron microscopy (SEM). The filler average size (µm) obtained by SEM were: Esthet-X (E) 1.16; Esthet-X (D) 1.39; Filtek Supreme XT (E) 0.6 (nanocluster); Filtek Supreme XT (D) 1.14 (nanocluster); Grandio (E) 2.05 and Grandio (D) 3.1. Silica (SiO2), Ba and Al were observed through EDS. The shape of Esthet-X and Grandio fillers showed similar characteristics with high quantity of irregular inorganic particles and heterogeneous filler. However, Filtek Supreme XT showed spherical and regular particles with homogeneous distribution and sizes. Based in the analysis of nanofilled composites inorganic phase, inconsistencies of weight content, composition, shape and size can be stated between the literature and manufacturer's instructions.

  9. Normal variations in the isotopic composition of metabolically relevant transition metals in human blood

    Science.gov (United States)

    Van Heghe, L.; Cloquet, C.; Vanhaecke, F.

    2012-04-01

    Cu, Fe and Zn are transition metals with great catalytic, structural and regulating importance in the human body. Hence, an aberrant metabolism of these elements can have serious implications on the health of a person. It is assumed that, due to differences in isotope fractionation, the isotopic composition of these elements in whole blood of patients can be different from that in blood of healthy subjects. Therefore, isotopic analysis of the element affected by the disease can be a promising approach for early diagnosis. A method for isotopic analysis of Cu, Fe and Zn in human whole blood was developed. The simultaneous chromatographic isolation of these elements and the conditions for isotope ratio measurement via multi-collector ICP - mass spectrometry (MC-ICP-MS) were optimized. So far, only whole blood of supposedly healthy volunteers (reference population) was analyzed. Results for Fe confirmed the known differences in isotopic composition between male and female blood. It is also shown that other parameters can have influence as well, e.g., the isotopic composition of Zn seems to be governed by the diet.

  10. Origin of heavy Fe isotope compositions in high-silica igneous rocks: A rhyolite perspective

    Science.gov (United States)

    Du, De-Hong; Wang, Xiao-Lei; Yang, Tao; Chen, Xin; Li, Jun-Yong; Li, Weiqiang

    2017-12-01

    The origin of heavy Fe isotope compositions in high-silica (>70 wt% SiO2) igneous rocks remains a highly controversial topic. Considering that fluid exsolution in eruptive rocks is more straight-forward to constrain than in plutonic rocks, this study addresses the problem of Fe isotope fractionation in high-silica igneous rocks by measuring Fe isotope compositions of representative rhyolitic samples from the Neoproterozoic volcanic-sedimentary basins in southern China and the Triassic Tu Le Basin in northern Vietnam. The samples show remarkably varied δ56FeIRMM014 values ranging from 0.05 ± 0.05‰ to 0.55 ± 0.05‰, which is among the highest values reported from felsic rocks. The extensional tectonic setting and short melt residence time in magma chambers for the studied rhyolites rule out Soret diffusion and thermal migration processes as causes of the high δ56Fe values. Effects of volcanic degassing and fluid exsolution on bulk rock δ56Fe values for the rhyolites are also assessed using bulk rock geochemical indicators and Rayleigh fractionation models, and these processes are found to be insufficient to produce resolvable changes in Fe isotope compositions of the residual melt. The most probable mechanism accounting for heavy Fe isotope compositions in the high-silica rhyolites is narrowed down to fractional crystallization processes in the magma before rhyolite eruption. Removal of isotopically light Fe-bearing minerals (i.e. ulvöspinel-rich titanomagnetite, ilmenite and biotite) is proposed as the main cause of Fe isotope variation in silicic melts during magmatic evolution. This study implies that crystal fractionation is the dominant mechanism that controls Fe isotope fractionation in eruptive rocks and Fe isotopes could be used to study magmatic differentiation of high-silica magmas.

  11. The stable Cr isotopic compositions of chondrites and silicate planetary reservoirs

    Science.gov (United States)

    Schoenberg, Ronny; Merdian, Alexandra; Holmden, Chris; Kleinhanns, Ilka C.; Haßler, Kathrin; Wille, Martin; Reitter, Elmar

    2016-06-01

    The depletion of chromium in Earth's mantle (∼2700 ppm) in comparison to chondrites (∼4400 ppm) indicates significant incorporation of chromium into the core during our planet's metal-silicate differentiation, assuming that there was no significant escape of the moderately volatile element chromium during the accretionary phase of Earth. Stable Cr isotope compositions - expressed as the ‰-difference in 53Cr/52Cr from the terrestrial reference material SRM979 (δ53/52CrSRM979 values) - of planetary silicate reservoirs might thus yield information about the conditions of planetary metal segregation processes when compared to chondrites. The stable Cr isotopic compositions of 7 carbonaceous chondrites, 11 ordinary chondrites, 5 HED achondrites and 2 martian meteorites determined by a double spike MC-ICP-MS method are within uncertainties indistinguishable from each other and from the previously determined δ53/52CrSRM979 value of -0.124 ± 0.101‰ for the igneous silicate Earth. Extensive quality tests support the accuracy of the stable Cr isotope determinations of various meteorites and terrestrial silicates reported here. The uniformity in stable Cr isotope compositions of samples from planetary silicate mantles and undifferentiated meteorites indicates that metal-silicate differentiation of Earth, Mars and the HED parent body did not cause measurable stable Cr isotope fractionation between these two reservoirs. Our results also imply that the accretionary disc, at least in the inner solar system, was homogeneous in its stable Cr isotopic composition and that potential volatility loss of chromium during accretion of the terrestrial planets was not accompanied by measurable stable isotopic fractionation. Small but reproducible variations in δ53/52CrSRM979 values of terrestrial magmatic rocks point to natural stable Cr isotope variations within Earth's silicate reservoirs. Further and more detailed studies are required to investigate whether silicate

  12. The O and H stable isotope composition of freshwaters in the British Isles. 2. Surface waters and groundwater

    Directory of Open Access Journals (Sweden)

    W. G. Darling

    2003-01-01

    Full Text Available The utility of stable isotopes as tracers of the water molecule has a long pedigree. The study reported here is part of an attempt to establish a comprehensive isotopic 'baseline' for the British Isles as background data for a range of applications. Part 1 of this study (Darling and Talbot, 2003 considered the isotopic composition of rainfall in Britain and Ireland. The present paper is concerned with the composition of surface waters and groundwater. In isotopic terms, surface waters (other than some upland streams are poorly characterised in the British Isles; their potential variability has yet to be widely used as an aid in hydrological research. In what may be the first study of a major British river, a monthly isotopic record of the upper River Thames during 1998 was obtained. This shows high damping of the isotopic variation compared to that in rainfall over most of the year, though significant fluctuations were seen for the autumn months. Smaller rivers such as the Stour and Darent show a more subdued response to the balance between runoff and baseflow. The relationship between the isotopic composition of rainfall and groundwater is also considered. From a limited database, it appears that whereas Chalk groundwater is a representative mixture of weighted average annual rainfall, for Triassic sandstone groundwater there is a seasonal selection of rainfall biased towards isotopically-depleted winter recharge. This may be primarily the result of physical differences between the infiltration characteristics of rock types, though other factors (vegetation, glacial history could be involved. In the main, however, groundwaters appear to be representative of bulk rainfall within an error band of 0.5‰ δ18O. Contour maps of the δ18O and δ2H content of recent groundwaters in the British Isles show a fundamental SW-NE depletion effect modified by topography. The range of measured values, while much smaller than those for rainfall, still covers

  13. Measurement of natural carbon isotopic composition of acetone in human urine.

    Science.gov (United States)

    Yamada, Keita; Ohishi, Kazuki; Gilbert, Alexis; Akasaka, Mai; Yoshida, Naohiro; Yoshimura, Ryoko

    2016-02-01

    The natural carbon isotopic composition of acetone in urine was measured in healthy subjects using gas chromatography-combustion-isotope ratio mass spectrometry combined with headspace solid-phase microextraction (HS-SPME-GC-C-IRMS). Before applying the technique to a urine sample, we optimized the measurement conditions of HS-SPME-GC-C-IRMS using aqueous solutions of commercial acetone reagents. The optimization enabled us to determine the carbon isotopic compositions within ±0.2 ‰ of precision and ±0.3‰ of error using 0.05 or 0.2 mL of aqueous solutions with acetone concentrations of 0.3-121 mg/L. For several days, we monitored the carbon isotopic compositions and concentrations of acetone in urine from three subjects who lived a daily life with no restrictions. We also monitored one subject for 3 days including a fasting period of 24 h. These results suggest that changes in the availability of glucose in the liver are reflected in changes in the carbon isotopic compositions of urine acetone. Results demonstrate that carbon isotopic measurement of metabolites in human biological samples at natural abundance levels has great potential as a tool for detecting metabolic changes caused by changes in physiological states and disease.

  14. Elucidating the controls on the Mg isotopic composition of marine pore fluids

    Science.gov (United States)

    Chanda, P.; Fantle, M.

    2013-12-01

    The Sr and Mg isotopic composition of pore fluids and carbonates from the Neogene section of Ocean Drilling Project Site 806B are reported (87Sr/86Sr and δ26Mg, measured using a Thermo Scientific Neptune Plus multi-collector ICP-MS). Site 806B, located on the northern margin of the Ontong Java Plateau, hosts a thick (776 m cored, depth to basement ~ 1200 m), relatively continuous, carbonate-rich section (between 83 and 96% CaCO3). Our goal in the current study is to use the Sr and Mg isotope data of pore fluids and carbonates to address open questions regarding (1) the extent to which the pore fluid chemistry is overprinted by calcite recrystallization, (2) the effects of diagenesis on bulk carbonate chemistry, and (3) the likelihood of preserving secular seawater δ26Mg trends in pore fluids. Accordingly, the current study compares and contrasts the isotopic and elemental data between adjacent ODP Sites 806B and 807A, which have similar depositional histories, carbonate contents, and pore fluid chemistries. The measured 87Sr/86Sr ratios of pore fluids at 806B range smoothly from 0.70914 at 4.45 mbsf to 0.70851 at 509.3 mbsf, similar (though offset relative) to the bulk carbonate trend (0.70918 to 0.70877 between 1.11 and 501.94 mbsf). The δ26MgDSM3 of 806B pore fluids generally increases from -0.86‰ at 4.45 mbsf to -0.17‰ at 679.0 mbsf. The overall trend is consistent with previously collected δ26Mg data at 807A [1]; there is, however, a significant difference in pore fluid δ26Mg between the two sites at depths of 300 to 600 mbsf. At these depths, 806B pore fluid δ26Mg values are +0.2 to 0.3‰ relative to 807A at similar depths [1]. The application of a depositional reactive transport model to the Sr isotope data suggests that bulk carbonate recrystallization rates at 806B are similar to those at 807A (histories of the sedimentary column (the latter is suggested by the differences in δ26Mg trends at depth). Preliminary model results suggest that

  15. Natural variations in calcium isotope composition as a monitor of bone mineral balance in humans.

    Science.gov (United States)

    Skulan, J.; Anbar, A.; Thomas, B.; Smith, S.

    2004-12-01

    The skeleton is the largest reservoir of calcium in the human body and is responsible for the short term control of blood levels of this element. Accurate measurement of changes in bone calcium balance is critical to understanding how calcium metabolism responds to physiological and environmental changes and, more specifically, to diagnosing and evaluating the effectiveness of treatments for osteoporosis and other serious calcium-related disorders. It is very difficult to measure bone calcium balance using current techniques, however, because these techniques rely either on separate estimates of bone resorption and formation that are not quantitatively comparable, or on complex and expensive studies of calcium kinetics using administered isotopic tracers. This difficulty is even more apparent and more severe for measurements of short-term changes in bone calcium balance that do not produce detectable changes in bone mineral density. Calcium isotopes may provide a novel means of addressing this problem. The foundation of this isotope application is the ca. 1.3 per mil fractionation of calcium during bone formation, favoring light calcium in the bone. This fractionation results in a steady-state isotopic offset between calcium in bone and calcium in soft tissues, blood and urine. Perturbations to this steady state due to changes in the net formation or resorption of bone should be reflected in changes in the isotopic composition of soft tissues and fluids. Here we present evidence that easily detectable shifts in the natural calcium isotope composition of human urine rapidly reflect changes in bone calcium balance. Urine from subjects in a 17-week bed rest study was analyzed for calcium isotopic composition. Bed rest promotes net resorption of bone, shifting calcium from bone to soft tissues, blood and urine. The calcium isotope composition of patients in this study shifted toward lighter values during bed rest, consistent with net resorption of isotopically

  16. 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

  17. Oxygen isotopic composition of mammal bones as a new tool for studying ratios of paleoenvironmental water and paleoclimates

    International Nuclear Information System (INIS)

    Longinelli, A.

    1984-04-01

    The purpose of this study is to try to establish quantitative relationships between the average oxygen isotopic composition of local meteoric water, the oxygen isotopic composition of mammal body water and the oxygen isotopic composition of phosphate in mammal bones. These relationships, after calibration of the method on living specimens, would allow quantitative paleoclimatological research based on the measurement of delta 18 O(PO 4 3- ) of fossil mammal bones

  18. Determination of the hydrogen isotopic compositions of organic materials and hydrous minerals using thermal combustion laser spectroscopy.

    Science.gov (United States)

    Koehler, Geoff; Wassenaar, Leonard I

    2012-04-17

    Hydrogen isotopic compositions of hydrous minerals and organic materials were measured by combustion to water, followed by optical isotopic analysis of the water vapor by off-axis integrated cavity output spectroscopy. Hydrogen and oxygen isotopic compositions were calculated by numerical integration of the individual isotopologue concentrations measured by the optical spectrometer. Rapid oxygen isotope exchange occurs within the combustion reactor between water vapor and molecular oxygen so that only hydrogen isotope compositions may be determined. Over a wide range in sample sizes, precisions were ±3-4 per mil. This is comparable but worse than continuous flow-isotope ratio mass spectroscopy (CF-IRMS) methods owing to memory effects inherent in water vapor transfer. Nevertheless, the simplicity and reduced cost of this analysis compared to classical IRMS or CF-IRMS methods make this an attractive option to determine the hydrogen isotopic composition of organic materials where the utmost precision or small sample sizes are not needed.

  19. Environmental forcing does not induce diel or synoptic variation in the carbon isotope content of forest soil respiration

    Science.gov (United States)

    Bowling, D. R.; Egan, J. E.; Hall, S. J.; Risk, D. A.

    2015-08-01

    Recent studies have examined temporal fluctuations in the amount and carbon isotope content (δ13C) of CO2 produced by the respiration of roots and soil organisms. These changes have been correlated with diel cycles of environmental forcing (e.g., sunlight and soil temperature) and with synoptic-scale atmospheric motion (e.g., rain events and pressure-induced ventilation). We used an extensive suite of measurements to examine soil respiration over 2 months in a subalpine forest in Colorado, USA (the Niwot Ridge AmeriFlux forest). Observations included automated measurements of CO2 and δ13C of CO2 in the soil efflux, the soil gas profile, and forest air. There was strong diel variability in soil efflux but no diel change in the δ13C of the soil efflux (δR) or the CO2 produced by biological activity in the soil (δJ). Following rain, soil efflux increased significantly, but δR and δJ did not change. Temporal variation in the δ13C of the soil efflux was unrelated to measured environmental variables, and we failed to find an explanation for this unexpected result. Measurements of the δ13C of the soil efflux with chambers agreed closely with independent observations of the isotopic composition of soil CO2 production derived from soil gas well measurements. Deeper in the soil profile and at the soil surface, results confirmed established theory regarding diffusive soil gas transport and isotopic fractionation. Deviation from best-fit diffusion model results at the shallower depths illuminated a pump-induced ventilation artifact that should be anticipated and avoided in future studies. There was no evidence of natural pressure-induced ventilation of the deep soil. However, higher variability in δ13C of the soil efflux relative to δ13C of production derived from soil profile measurements was likely caused by transient pressure-induced transport with small horizontal length scales.

  20. Environmental forcing does not induce diel or synoptic variation in carbon isotope content of forest soil respiration

    Science.gov (United States)

    Bowling, D. R.; Egan, J. E.; Hall, S. J.; Risk, D. A.

    2015-04-01

    Recent studies have examined temporal fluctuations in the amount and carbon isotope content (δ13C) of CO2 produced by respiration of roots and soil organisms. These changes have been correlated with diel cycles of environmental forcing (e.g., sunlight and soil temperature) and with synoptic-scale atmospheric motion (e.g., rain events and pressure-induced ventilation). We used an extensive suite of measurements to examine soil respiration over two months in a subalpine forest in Colorado, USA (the Niwot Ridge AmeriFlux forest). Observations included automated measurements of CO2 and δ13C of CO2 in the soil efflux, the soil gas profile, and forest air. There was strong diel variability in soil efflux, but no diel change in the δ13C of the soil efflux (δR) or the CO2 produced by biological activity in the soil (δJ). Following rain, soil efflux increased significantly, but δR and δJ did not change. Temporal variation in the δ13C of the soil efflux was unrelated to measured environmental variables. Measurements of the δ13C of the soil efflux with chambers agreed closely with independent observations of the isotopic composition of soil CO2 production derived from soil gas well measurements. Deeper in the soil profile and at the soil surface, results confirmed established theory regarding diffusive soil gas transport and isotopic fractionation. Deviation from best-fit diffusion model results at the shallower depths illuminated a pump-induced ventilation artifact that should be anticipated and avoided in future studies. There was no evidence of natural pressure-induced ventilation of the deep soil. However, higher variability of δ13C of the soil efflux relative to δ13C of production derived from soil profile measurements was likely caused by transient pressure-induced transport with small horizontal length scales.

  1. Study on the meat isotopic composition for origin identification

    Directory of Open Access Journals (Sweden)

    Irina Chernukha

    2018-03-01

    Full Text Available Russian consumer and governmental authorities are equally concerned to know where food products come from. This requires more accurate and specialized methods for the evaluation of geographical location. The following methods are used: chemometrics, histological and histochemical, genomic and proteomic, microbiological, immunochemical and mass spectrometric. Method of stable isotope analysis is becoming increasingly promising nowadays for the identification of meat and meat products' place of origin. The isotope ratios of the four elements - carbon, nitrogen, oxygen and hydrogen, are mainly determined. The method is successfully used to identify a country of origin of wines, juices and water. The aim of the research was to study the stable isotope ratios for pork and beef samples purchased in Moscow supermarkets (Russian Federation. The country of production of meat samples was determined according to specifications and/or labels. The geography of countries of meat samples origin includes Europe, both America continents and Australia. Databases collected by the All-Russian Scientific Research Institute of the Brewing, Non-Alcoholic and Wine Industrywere used for the analysis and interpretation of the results. Values of 13С/12С, δ13С, 18О/16О, δ18О, 2Н/1Н, δ2Н for 30 pork and beef samples from 13 countries were obtained. Differences in stable isotope ratios were found depending on place of origin. The data correlated with the oxygen isotope characteristics for wine, which were in the range from 2.5 to 4.5 ppm. According to the 13С/12С, δ13С results, the assumption was made about a false indication of the region for the beef sample. Despite the fact that beef was labeled as a product of Lithuania, the region of origin was most probably defined as Germany. The studies carried out showed the possibility to identify the region of raw meat origin by the stable isotope ratio.

  2. The concentration and isotopic composition of diffusible Nd in fresh and marine waters

    Science.gov (United States)

    Dahlqvist, Ralf; Andersson, Per S.; Ingri, Johan

    2005-04-01

    Variations in the Nd isotopic composition of ocean water through time, recorded in marine deposits, are suggested to document changes in erosional input and ocean circulation. Thus characterization of the dissolved Nd component in seawater is important. But few attempts have been made to directly measure truly dissolved Nd. Here we report Nd data, obtained using the technique of diffusive gradients in thin-films (DGT) designed to measure in situ, diffusible labile trace metals in aqueous solutions. The method samples free ions and possibly very small complexes. The concentration and isotopic composition of Nd in fresh, brackish and seawater have been determined with DGT, analyzed with thermal ionization mass-spectrometry, and compared with filtered and bulk water samples. Concentrations measured in water samples and with DGT show that the relative amount of diffusible Nd increases with salinity, from being about 10% in the fresh water to 42% in seawater. At each sampled site, the isotopic composition of Nd in the water shows a similar isotopic composition, within errors, with Nd sampled using the DGT method. These results indicate that there is a complete exchange between the particulate/colloidal fraction and the truly dissolved phase. Therefore our findings suggest that solute Nd reflects both the isotopic composition of the marine sediments and the bulk water.

  3. Report of International Workshop on tracing isotopic composition of past and present precipitation - opportunities for climate and water studies

    International Nuclear Information System (INIS)

    1995-01-01

    The Workshop on Tracing Isotopic Composition of Past and Present Precipitation - Opportunities for Climate and Water Studies, was jointly organized by the World Meteorological Organization (WMO), the International Atomic Energy Agency (IAEA), Past Global Changes (PAGES) - a core project of the International Geosphere - Biosphere Programme (IGBP), and the International Association of Hydrological Sciences (IAHS). The Global Network ''Isotopes in Precipitation'' (GNIP) was initiated by IAEA in 1958 and became operational in 1961. The main objective was to collect systematic data on isotopic content of precipitation on a global scale and to establish temporal and spatial variations of environmental isotopes in precipitation. The network is now expected to serve additional purposes, namely as a benchmark for the interpretation of paleo-records, as a validation tool for Global Circulation Models, and for establishing large-scale regional (and continental-scale) waster balances. Furthermore, the structure of GNIP should be strengthened. This includes the build-up of: stations located close to major natural climatic archives (e.g. Greenland, mountain areas); stations which represent climatically sensitive areas (indicated by GCM's and biome models). Isotope monitoring of river outflow from major continental basins should be initiated. This could be realized in co-operation with the UNEP/WHO Global Environmental Monitoring System-Water (GEMS-Water). The deuterium excess parameter (δ) is of particular importance in climate modelling and in the understanding of hydro-meteorological pathways. The use of the deuterium excess imposes strict requirements on the accuracy of deuterium and oxygen-18 analysis. A GNIP-based worldwide documentation of quality control regarding sampling, shipping and measurements is needed. The IAEA/WMO database and other isotope data sets should be included in the World Data Center A for palaeo-climatology. Refs, figs, tabs

  4. Heterogeneities in the solar nebula. [oxygen isotopic composition in carbonaceous chondrites

    Science.gov (United States)

    Clayton, R.; Grossman, L.; Mayeda, T. K.; Onuma, N.

    1974-01-01

    Oxygen isotopic compositions of the high-temperatue phases in carbonaceous chondrites define a mixing line with an O-16 rich component and show little superimposed chemical isotope fractionation. Within a single inclusion in Allende, variations of delta O-18 and delta O-17 of 39% are found. The ordinary chondrites are slightly displaced from the terrestrial fractionation trend, implying that at least 0.2% of the oxygen in terrestrial rocks was derived from the O-16 rich component.

  5. Oxygen isotopic composition of fulgurites from the Egyptian Sahara and other locations.

    Science.gov (United States)

    Longinelli, Antonio; Serra, Romano; Sighinolfi, Giampaolo; Selmo, Enricomaria; Sgavetti, Maria

    2012-09-15

    Fulgurites are glassy crusts or hollow glassy tubes formed by the impact of a lightning strike on a target material on the Earth's surface. The oxygen isotopic composition of fulgurites has never been measured and, consequently, it is unknown whether or not isotopic fractionations take place between the target material and the fulgurite glass during the lightning event which is an excellent natural example of extremely fast melting process. Following well-established procedures (high-temperature reaction of the fulgurite material with BrF(5), conversion into CO(2) of the evolved O(2) and measurement of the(18)O/(16)O ratio on a Finnigan Delta S mass spectrometer) we measured for the first time the oxygen isotopic composition of sets of fulgurites coming from various locations on the Earth's surface. The range of isotopic values is quite large, probably reflecting the oxygen isotopic values of the target materials. In the case of fulgurites from the Sahara Desert the isotopic values obtained from the bulk material, quartz crystals sticking to the fulgurite body, tiny samples of loose sand coming from fulgurite bubbles, and sand samples collected near the fulgurites, are very close to one another. Although we do not have indisputable evidence, we conclude that, at least in the case of oxygen, the fusion process of the material struck by lightning, as well as all the extremely fast high-temperature fusion processes, probably take place without any isotopic fractionation effect. Copyright © 2012 John Wiley & Sons, Ltd.

  6. Milk fatty acid composition and conjugated linoleic acid content of ...

    African Journals Online (AJOL)

    2015-10-20

    Oct 20, 2015 ... ISSN 0375-1589 (print), ISSN 2221-4062 (online). Publisher: South African Society for Animal Science http://dx.doi.org/10.4314/sajas.v45i4.7. Milk fatty acid composition and conjugated linoleic acid content of Jersey and. Fleckvieh x Jersey cows in a pasture-based feeding system. B. Sasanti1,2, S. Abel2, ...

  7. The carbon isotopes ratio and trace metals content determinations in some Transylvanian fruit juices

    Science.gov (United States)

    Dehelean, A.; Magdas, D. A.; Cristea, G.

    2012-02-01

    This work presents a preliminary study on the carbon isotope signature and trace metal content investigated on the soil-plant-fruit pulp chain. The samples were collected from two Transylvanian areas namely Alba and Salaj. The average value of the δ13C at the soil surface was around δ13C ≈ -27%° and important differences of the δ13C values between the two studied areas were not observed. Meanwhile, differences between fruit pulp of grape juice and the pulp of pear juice relived a difference of about 1.5%° for δ13C values.

  8. Nuclear Facility Isotopic Content (NFIC) Waste Management System to provide input for safety envelope definition

    International Nuclear Information System (INIS)

    Genser, J.R.

    1992-01-01

    The Westinghouse Savannah River Company (WSRC) is aggressively applying environmental remediation and radioactive waste management activities at the US Department of Energy's Savannah River Site (SRS) to ensure compliance with today's challenging governmental laws and regulatory requirements. This report discusses a computer-based Nuclear Facility Isotopic Content (NFIC) Waste Management System developed to provide input for the safety envelope definition and assessment of site-wide facilities. Information was formulated describing the SRS ''Nuclear Facilities'' and their respective bounding inventories of nuclear materials and radioactive waste using the NFIC Waste Management System

  9. Isotope composition and volume of Earth´s early oceans

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Bird, Dennis K.; Rosing, Minik Thorleif

    2012-01-01

    Oxygen and hydrogen isotope compositions of Earth´s seawater are controlled by volatile fluxes among mantle, lithospheric (oceanic and continental crust), and atmospheric reservoirs. Throughout geologic time the oxygen mass budget was likely conserved within these Earth system reservoirs, but hyd......Oxygen and hydrogen isotope compositions of Earth´s seawater are controlled by volatile fluxes among mantle, lithospheric (oceanic and continental crust), and atmospheric reservoirs. Throughout geologic time the oxygen mass budget was likely conserved within these Earth system reservoirs......, but hydrogen´s was not, as it can escape to space. Isotopic properties of serpentine from the approximately 3.8 Ga Isua Supracrustal Belt in West Greenland are used to characterize hydrogen and oxygen isotope compositions of ancient seawater. Archaean oceans were depleted in deuterium [expressed as Î......´D relative to Vienna standard mean ocean water (VSMOW)] by at most 25± 5‰, but oxygen isotope ratios were comparable to modern oceans. Mass balance of the global hydrogen budget constrains the contribution of continental growth and planetary hydrogen loss to the secular evolution of hydrogen isotope ratios...

  10. Determination of isotopic composition of uranium in microparticles by secondary ion mass spectrometry

    International Nuclear Information System (INIS)

    Veniaminov, N.N.; Kolesnikov, O.N.; Stebel'kov, V.A.

    1992-01-01

    Aerosol particles including uranium in their composition are specific atmospheric polutants. Uranium is used as nuclear fuel in atomic power stations and in spacecraft power units, and also as a component of nuclear warheads. In order to monitor the discharge of uranium-containing aerosol particles to the atmosphere, they must first be identified. As an example, one may cite an investigation of the elemental composition and radioactivity of particles formed in the accident at the Chernobyl atomic power station. One of the most informative indicators of the origin of uranium-containing aerosol particles is the isotopic composition of the uranium. Secondary ion mass spectrometry (SIMS) offers unique possibilities for the measurement of isotope ratios in individual microscopic objects. At the same time, a measurement of isotope ratios of sulfur in microsection of galenite PbS 2 has shown that the application of SIMS for these purposes is seriously limited by the difference in yield of secondary ions for isotopes with different masses. These discrimination effects, in the case of light elements such as boron, may result in distortion of the isotope ratios by several percent. In the case of heavy elements, however, the effect is less significant, amounting to about 0.5% for lead isotopes. 13 refs., 3 figs., 1 tab

  11. Fe Isotopic Composition of Presolar SiC Mainstream Grains

    Science.gov (United States)

    Tripa, C. E.; Pellin, M. J.; Savina, M. R.; Davis, A. M.; Lewis, R. S.; Clayton, R. N.

    2002-01-01

    Iron isotopic distribution was measured in SiC mainstream grains from the Murchison meteorite by time-of-flight resonance ionization mass spectrometry. All grains exhibit 54Fe depletions of 50 to 200, lower than what are predicted by calculations of s-process nucleosynthesis in AGB stars. Additional information is contained in the original extended abstract.

  12. Chemical and sulphur isotope compositions of pyrite in the ...

    Indian Academy of Sciences (India)

    ground uranium mine in India. Besides uranium;. Cu, Mo and Ni have previously been recovered and presently magnetite is being recovered as a by-product. Similar to other deposits in the. SSZ, the Jaduguda deposit is hosted by strongly. Keywords. Pyrite; minor element; sulphur isotope; evolution; Jaduguda; Singhbhum; ...

  13. Carbon isotopic composition of fossil leaves from the Early ...

    Indian Academy of Sciences (India)

    Stable carbon isotope analysis of fossil leaves from the Bhuj Formation, western India was carried out to infer the prevailing environmental conditions. Compression fossil leaves such as Pachypteris indica, Otozamite kachchhensis, Brachyphyllum royii and Dictyozamites sp. were recovered from three sedimentary ...

  14. Carbon and oxygen isotope compositions of the carbonate facies in ...

    Indian Academy of Sciences (India)

    The Vindhyan sedimentary succession in central India spans a wide time bracket from the Paleopro- terozoic to the Neoproterozoic period.Chronostratigraphic significance of stable carbon and oxygen isotope ratios of the carbonate phase in Vindhyan sediments has been discussed in some recent studies.However,the ...

  15. Carbon and oxygen isotope compositions of the carbonate facies

    Indian Academy of Sciences (India)

    The Vindhyan sedimentary succession in central India spans a wide time bracket from the Paleopro- terozoic to the Neoproterozoic period.Chronostratigraphic significance of stable carbon and oxygen isotope ratios of the carbonate phase in Vindhyan sediments has been discussed in some recent studies.However,the ...

  16. Carbon and oxygen isotope compositions of the carbonate facies in ...

    Indian Academy of Sciences (India)

    The Vindhyan sedimentary succession in central India spans a wide time bracket from the Paleopro- terozoic to the Neoproterozoic period. Chronostratigraphic significance of stable carbon and oxygen isotope ratios of the carbonate phase in Vindhyan sediments has been discussed in some recent studies. However, the ...

  17. The effect of soll water conditions on carbon isotope discrimination and minerals contents in spring-planted wheat

    International Nuclear Information System (INIS)

    Zhu Lin; Liang Zongsuo; Xu Xing; Li Shuhua

    2008-01-01

    Carbon isotope discrimination (triangle open 13 C) has been proposed as indirect selection criterion for transpiration efficiency and grain yield in wheat. However, because of high cost for triangle open 13 C analysis, attempts have been made to identify alternative screening criteria. Ash content (m a ) has been proposed as an alternative criterion for triangle open 13 C in wheat and barley. A pot experiment with three water treatments (45% ± 5% FC, 55% ± 5% FC and 75% ± 5%FC) was conducted and flag leaf triangle open 13 C (triangle openL a ), contents of ash, potassium (K), magnesium (Mg) and calcium (Ca) were measured to study the relationships between triangle open, mineral composition in spring planted bread wheat (Triticum aestivum L.). In the light of the results obtained in this research, the traits measured showed significant differences among the three water treatments. There were variations in triangle openL a between the genotypes derived from contrasting environments. The improved varieties or advanced lines bred in irrigated areas displayed higher triangle open 13 C values, while the improved and local varieties bred in rain-fed areas exhibited lower triangle open 13 C values Significant positive correlations were found between triangle open 13 C and m a in seedlings and second fully developed leaves at elongation stage and in flag leaves at anthesis stage in severe drought treatment (T 1 ) (r=0.790, P 13 C was negatively associated with potassium (K) content in flag leaves in T 2 (r=0.813, P 2 and T 3 (r=0.725, P 13 C and calcium (Ca) content in flag leaves in T 3 (r=0.708, P a is a possible alternative criterion of triangle open 13 C in vegetative organs especially in stressed environments. K, Mg and Ca contents in flag leaf under moderate water stress or feasible water conditions might be new predictive criteria of triangle openL a . (authors)

  18. A Three End-Member Mixing Model Based on Isotopic Composition and Elemental Ratio

    Directory of Open Access Journals (Sweden)

    Kon-Kee Liu Shuh-Ji Kao

    2007-01-01

    Full Text Available A three end-member mixing model based on nitrogen isotopic composition and organic carbon to nitrogen ratio of suspended particulate matter in an aquatic environment has been developed. Mathematical expressions have been derived for the calculation of the fractions of nitrogen or organic carbon originating from three different sources of distinct isotopic and elemental compositions. The model was successfully applied to determine the contributions from anthropogenic wastes, soils and bedrock-derived sediments to particulate nitrogen and particulate organic carbon in the Danshuei River during the flood caused by Typhoon Bilis in August 2000. The model solutions have been expressed in a general form that allows applications to mixtures with other types of isotopic compositions and elemental ratios or in forms other than suspended particulate matter.

  19. Isotopic composition of carbon of certain sapropelites as an indicator of their formation

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, S; Klesment, I.; Punning, Ya.M.; Vaikmyae, R.

    1981-01-01

    Materials are presented on an investigation of the isotopic composition of carbon of three sapropelites, Chagan schist--of marine orgin, of the Jurassic age; schist of Borova Dola (Bulgarian People's Republic)-fascial type, lake with marine influence, of Upper Ecocene age; balkhashite--of contemporary origin, if formed of oil-containing algae. On the basis of the isotope composition of the carbon there is drawn the conclusion that the original biological substance of the Chagan schist and of balkhashite was subjected so strong bacterial action. The isotopic composition of the organic matter of the sapropelites can serve as a criterion of their genesis. It is shown that there exists a regularity of change of par. delta /sup 13/ C of sapropelites in dependence on the degree of metamorphism, on the fascial-genetic type of organic substance and on the conditions of sedimentary accumulations.

  20. The oxygen isotopic composition of the Sun inferred from captured solar wind.

    Science.gov (United States)

    McKeegan, K D; Kallio, A P A; Heber, V S; Jarzebinski, G; Mao, P H; Coath, C D; Kunihiro, T; Wiens, R C; Nordholt, J E; Moses, R W; Reisenfeld, D B; Jurewicz, A J G; Burnett, D S

    2011-06-24

    All planetary materials sampled thus far vary in their relative abundance of the major isotope of oxygen, (16)O, such that it has not been possible to define a primordial solar system composition. We measured the oxygen isotopic composition of solar wind captured and returned to Earth by NASA's Genesis mission. Our results demonstrate that the Sun is highly enriched in (16)O relative to the Earth, Moon, Mars, and bulk meteorites. Because the solar photosphere preserves the average isotopic composition of the solar system for elements heavier than lithium, we conclude that essentially all rocky materials in the inner solar system were enriched in (17)O and (18)O, relative to (16)O, by ~7%, probably via non-mass-dependent chemistry before accretion of the first planetesimals.

  1. Thallium-isotopic compositions of euxinic sediments as a proxy for global manganese-oxide burial

    Science.gov (United States)

    Owens, Jeremy D.; Nielsen, Sune G.; Horner, Tristan J.; Ostrander, Chadlin M.; Peterson, Larry C.

    2017-09-01

    Thallium (Tl) isotopes are a new and potentially powerful paleoredox proxy that may track bottom water oxygen conditions based on the global burial flux of manganese oxides. Thallium has a residence time of ∼20 thousand years, which is longer than the ocean mixing time, and it has been inferred that modern oxic seawater is conservative with respect to both concentration and isotopes. Marine sources of Tl have nearly identical isotopic values. Therefore, the Tl sinks, adsorption onto manganese oxides and low temperature oceanic crust alteration (the dominant seawater output), are the primary controls of the seawater isotopic composition. For relatively short-term, ∼million years, redox events it is reasonable to assume that the dominant mechanism that alters the Tl isotopic composition of seawater is associated with manganese oxide burial because large variability in low temperature ocean crust alteration is controlled by long-term, multi-million years, average ocean crust production rates. This study presents new Tl isotope data for an open ocean transect in the South Atlantic, and depth transects for two euxinic basins (anoxic and free sulfide in the water column), the Cariaco Basin and Black Sea. The Tl isotopic signature of open ocean seawater in the South Atlantic was found to be homogeneous with ε205Tl = -6.0 ± 0.3 (±2 SD, n = 41) while oxic waters from Cariaco and the Black Sea are -5.6 and -2.2, respectively. Combined with existing data from the Pacific and Arctic Oceans, our Atlantic data establish the conservatism of Tl isotopes in the global ocean. In contrast, partially- and predominantly-restricted basins reveal Tl isotope differences that vary between open-ocean (-6) and continental material (-2) ε205Tl, scaling with the degree of restriction. Regardless of the differences between basins, Tl is quantitatively removed from their euxinic waters below the chemocline. The burial of Tl in euxinic sediments is estimated to be an order of magnitude

  2. Reconstruction of the isotope activity content of heterogeneous nuclear waste drums.

    Science.gov (United States)

    Krings, Thomas; Mauerhofer, Eric

    2012-07-01

    Radioactive waste must be characterized in order to verify its conformance with national regulations for intermediate storage or its disposal. Segmented gamma scanning (SGS) is a most widely applied non-destructive analytical technique for the characterization of radioactive waste drums. The isotope specific activity content is generally calculated assuming a homogeneous matrix and activity distribution for each measured drum segment. However, real radioactive waste drums exhibit non-uniform isotope and density distributions most affecting the reliability and accuracy of activities reconstruction in SGS. The presence of internal shielding structures in the waste drum contributes generally to a strong underestimation of the activity and this in particular for radioactive sources emitting low energy gamma-rays independently of their spatial distribution. In this work we present an improved method to quantify the activity of spatially concentrated gamma-emitting isotopes (point sources or hot spots) in heterogeneous waste drums with internal shielding structures. The isotope activity is reconstructed by numerical simulations and fits of the angular dependent count rate distribution recorded during the drum rotation in SGS using an analytical expression derived from a geometric model. First results of the improved method and enhancements of this method are shown and are compared to each other as well as to the conventional method which assumes a homogeneous matrix and activity distribution. It is shown that the new model improves the accuracy and the reliability of the activity reconstruction in SGS and that the presented algorithm is suitable with respect to the framework requirement of industrial application. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Spurious and functional correlates of the isotopic composition of a generalist across a tropical rainforest landscape

    Directory of Open Access Journals (Sweden)

    Poirson Evan K

    2009-11-01

    Full Text Available Abstract Background The isotopic composition of generalist consumers may be expected to vary in space as a consequence of spatial heterogeneity in isotope ratios, the abundance of resources, and competition. We aim to account for the spatial variation in the carbon and nitrogen isotopic composition of a generalized predatory species across a 500 ha. tropical rain forest landscape. We test competing models to account for relative influence of resources and competitors to the carbon and nitrogen isotopic enrichment of gypsy ants (Aphaenogaster araneoides, taking into account site-specific differences in baseline isotope ratios. Results We found that 75% of the variance in the fraction of 15N in the tissue of A. araneoides was accounted by one environmental parameter, the concentration of soil phosphorus. After taking into account landscape-scale variation in baseline resources, the most parsimonious model indicated that colony growth and leaf litter biomass accounted for nearly all of the variance in the δ15N discrimination factor, whereas the δ13C discrimination factor was most parsimoniously associated with colony size and the rate of leaf litter decomposition. There was no indication that competitor density or diversity accounted for spatial differences in the isotopic composition of gypsy ants. Conclusion Across a 500 ha. landscape, soil phosphorus accounted for spatial variation in baseline nitrogen isotope ratios. The δ15N discrimination factor of a higher order consumer in this food web was structured by bottom-up influences - the quantity and decomposition rate of leaf litter. Stable isotope studies on the trophic biology of consumers may benefit from explicit spatial design to account for edaphic properties that alter the baseline at fine spatial grains.

  4. The isotopic composition of methane in the stratosphere: high-altitude balloon sample measurements

    Directory of Open Access Journals (Sweden)

    T. Röckmann

    2011-12-01

    Full Text Available The isotopic composition of stratospheric methane has been determined on a large suite of air samples from stratospheric balloon flights covering subtropical to polar latitudes and a time period of 16 yr. 154 samples were analyzed for δ13C and 119 samples for δD, increasing the previously published dataset for balloon borne samples by an order of magnitude, and more than doubling the total available stratospheric data (including aircraft samples published to date. The samples also cover a large range in mixing ratio from tropospheric values near 1800 ppb down to only 250 ppb, and the strong isotope fractionation processes accordingly increase the isotopic composition up to δ13C = −14‰ and δD = +190‰, the largest enrichments observed for atmospheric CH4 so far. When analyzing and comparing kinetic isotope effects (KIEs derived from single balloon profiles, it is necessary to take into account the residence time in the stratosphere in combination with the observed mixing ratio and isotope trends in the troposphere, and the range of isotope values covered by the individual profile. The isotopic composition of CH4 in the stratosphere is affected by both chemical and dynamical processes. This severely hampers interpretation of the data in terms of the relative fractions of the three important sink mechanisms (reaction with OH, O(1D and Cl. It is shown that a formal sink partitioning using the measured data severely underestimates the fraction removed by OH, which is likely due to the insensitivity of the measurements to the kinetic fractionation in the lower stratosphere. Full quantitative interpretation of the CH4 isotope data in terms of the three sink reactions requires a global model.

  5. Determining Isotopic Composition of Dissolved Nitrate Using Bacterial Denitrification Followed by Laser Spectroscopy

    International Nuclear Information System (INIS)

    Yan Tiezhu; Lee Zhi Yi, Amelia; Heiling, Maria; Weltin, Georg; Toloza, Arsenio; Resch, Christian

    2016-01-01

    Nitrate (NO 3 - ) pollution is a prevalent problem that can cause water quality degradation and eutrophication of water bodies. Quantifying the nitrogen and oxygen isotopic composition of nitrates will allow for better identification of their potential sources, which in turn will assist in remediation of contaminated water and the designing of future water management practices. In this research bacterial denitrification followed by laser spectroscopy are used to determine isotopic composition of δ 15 N and δ 18 O of dissolved nitrates. The objective of the project is to establish a standard operating procedure (SOP) that outlines the best practices for both methods in sequence and designed to be used as a technical guideline

  6. Nitrate distribution and isotopic composition in vadose-zone sediments underlying large dairy operations

    Science.gov (United States)

    Esser, B. K.; Singleton, M. J.; Moran, J. E.; Roberts, S. K.; Barton, C. G.; Watanabe, N.; Harter, T.

    2009-12-01

    Understanding the transport and cycling of nitrate in the vadose zone is essential to 1) linking agronomic models of nitrate flux out of the root zone to groundwater models of nitrate loading at the water table, 2) quantifying the impact of vadose-zone biogeochemical processes on nitrate isotopic composition for the purpose of source attribution, and 3) constraining transport time scales through the vadose zone in order to assess the impact of changes in agricultural nutrient management on underlying groundwater quality. In this study, we have investigated the isotopic composition of water-leachable nitrate extracted from sediment cores underlying three dairy operations in the southern San Joaquin Valley of California. One of the dairy operations is new (less than ten years old) and is sited on former range land; the other two operations are older (with one having been continuously operated for over a century). All use dairy wastewater for irrigation, and have vadose zones of 25-60 meters thickness developed in sedimentary sequences dominated by alluvial fan deposits. Sediment core samples from a UC-Davis monitor well drilling program were extracted with an equal amount of ultrapure water, and analyzed for nitrate isotopic composition using the denitrifying bacteria method at LLNL. The range in nitrate isotopic composition (δ15N,air = 4.8 to 26.6 permil, δ18O,VSMOW = -0.3 to 16.2 permil) is large, comparable to isotopic compositions observed in dairy wastewater-impacted groundwaters (Singleton et al., 2007, ES&T 41:759-765), and varies from site to site. The range is the largest on the oldest operation (δ15N = 5.2 to 26.6), and most tightly clustered on the youngest operation (δ15N = 4.8 to 7.8). Leachable nitrate-δ18O correlates with nitrate-δ15N along a characteristic denitrification trend for individual cores. Leachable nitrate-δ15N is not simply correlated with leachable nitrate concentration (which is generally high in shallow sediments and decreases

  7. Seasonal effects on carbon isotope composition of cactus in a desert environment

    International Nuclear Information System (INIS)

    Sutton, B.G.; Ting, I.P.; Troughton, J.H.

    1976-01-01

    It is stated that two different enzymes are involved in the fixation of CO 2 in cactus plants under light and dark conditions and that because these enzymes discriminate against 13 C in the atmosphere to different extents the wide range of C isotope discrimination values (delta 13 C) found in these plants has been attributed to different contributions of dark and light fixation to C gain. The proportion of total C fixed at night can be altered, however, by environmental variables such as temperature, water status, and photoperiod, and predictable changes in delta 13 C have been observed when these environmental conditions have been varied. The studies, with few exceptions, have, however, been made under artificial conditions. In the studies described here the sensitivity of the delta 13 C ratios to seasonal environmental influences was examined in a natural system. It was found that the C isotope composition of the plants did not change during the experiments, indicating insensitivity to short term seasonal influences. The experimental site was at an altitude of 289 m. at the Palm Desert, California. Total titratable acidity and malic acid content were determined in addition to the delta 13 C ratio. The extent of the diurnal change in the titratable acidity varied with rainfall, particularly in the autumn. It is concluded from the data obtained that the delta 13 C ratio of the plants studied is relatively insensitive to short term seasonal changes under natural desert conditions. The data also confirm that no exogenous CO 2 is fixed in the light in this environment. The varying delta 13 C ratios observed in wild populations of cactus are a result of long term environmental differences other than seasonal effects, and hence credence is given to the use of such ratios for the reconstruction of past climates. (U.K.)

  8. Standard Test Methods for Constituent Content of Composite Materials

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 These test methods determine the constituent content of composite materials by one of two approaches. Method I physically removes the matrix by digestion or ignition by one of seven procedures, leaving the reinforcement essentially unaffected and thus allowing calculation of reinforcement or matrix content (by weight or volume) as well as percent void volume. Method II, applicable only to laminate materials of known fiber areal weight, calculates reinforcement or matrix content (by weight or volume), and the cured ply thickness, based on the measured thickness of the laminate. Method II is not applicable to the measurement of void volume. 1.1.1 These test methods are primarily intended for two-part composite material systems. However, special provisions can be made to extend these test methods to filled material systems with more than two constituents, though not all test results can be determined in every case. 1.1.2 The procedures contained within have been designed to be particularly effective for ce...

  9. Stable isotope compositions (O-C) of reef fish otoliths from the Taiaro lagoon (Tuamotu, French Polynesia): isotopic and biologic implications

    International Nuclear Information System (INIS)

    Blamart, D.; Juillet-Leclerc, A.; Ouahdi, R.; Escoubeyrou, K.; Lecomte-Finiger, R.

    2002-01-01

    Nuclei (larval stage) and outer parts (adult stage) of fish otoliths from the Taiaro closed lagoon (French Polynesia) and adjacent ocean have been analysed for the C-O isotopic compositions. δ 18 O values of the nuclei of both populations indicate that isotopic equilibrium is reached. This implies that the lagoonal fish population has done its complete biological cycle in the lagoon and represents an adaptation in a closed system. δ 18 O values of the outer parts show a slight isotopic disequilibrium ( 13 C values exhibit a strong isotopic disequilibrium related to metabolic activity. (authors)

  10. Numerical modeling of radioactive neutron capture influence of Hf isotopic composition dynamics rate in the RBMK-1500 reactor

    CERN Document Server

    Jurkevicius, A; Auzelyte, V; Remeikis, V

    2000-01-01

    The nuclide composition of the nuclear fuel and isotopic composition of the hafnium in the radial neutron flux detectors of the RBMK-1500 reactor were numerically modelled. The sequence SAS2 from package SCALE 4.3 was used for calculations. The nuclear fuel nuclide concentrations, the concentration of Hf isotopes, the neutron absorption rate on Hf isotopes and summary absorption rate dependences on the fuel assembly burn up are presented. (author)

  11. Uncertainties in the oxygen isotopic composition of barium sulfate induced by coprecipitation of nitrate.

    Science.gov (United States)

    Michalski, Greg; Kasem, Michelle; Rech, Jason A; Adieu, Sabine; Showers, William S; Genna, Bernie; Thiemens, Mark

    2008-10-01

    Coprecipitation of nitrate and sulfate by barium has probably resulted in significant error in numerous studies dealing with the oxygen isotopic composition of natural sulfates using chemical/thermal conversion of BaSO(4) and analysis by isotope ratio mass spectrometry. In solutions where NO(3) (-)/SO(4) (2-) molar ratios are above 2 the amount of nitrate coprecipitated with BaSO(4) reaches a maximum of approximately 7% and decreases roughly linearly as the molar ratio decreases. The fraction of coprecipitated nitrate appears to increase with decreasing pH and is also affected by the nature of the cations in the precipitating solution. The size of the oxygen isotope artifact in sulfate depends both on the amount of coprecipitated nitrate and the delta(18)O and Delta(17)O values of the nitrate, both of which can be highly variable. The oxygen isotopic composition of sulfate extracted from atmospheric aerosols or rain waters are probably severely biased because photochemical nitrate is usually also present and it is highly enriched in (18)O (delta(18)O approximately 50-90 per thousand) and has a large mass-independent isotopic composition (Delta(17)O approximately 20-32 per thousand). The sulfate delta(18)O error can be 2-5 per thousand with Delta(17)O artifacts reaching as high as 4.0 per thousand.

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

    Science.gov (United States)

    Wang, Zhuhong; Chen, Jiubin; Zhang, Ting

    2017-05-18

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

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

    Directory of Open Access Journals (Sweden)

    Zhuhong Wang

    2017-05-01

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

  14. First Measurements of Osmium Concentration and Isotopic Composition in a Summit, Greenland Ice Core

    Science.gov (United States)

    Osterberg, E. C.; Sharma, M.; Hawley, R. L.; Courville, Z.

    2010-12-01

    Osmium (Os) is one of the rarer elements in the environment and therefore one of the most difficult to accurately measure, but its isotopically distinctive crustal, mantle-derived, and extra-terrestrial sources make it a valuable geochemical tracer. Recent state-of-the-art analyses of precipitation, river water, and ocean water samples from around the world have revealed elevated concentrations of Os with a characteristically low (unradiogenic) Os isotopic signature (187Os/188Os). This unusual low Os isotopic signal has been interpreted as evidence for widespread Os pollution due to the smelting of Platinum Group Element (PGE) sulfide ores for use in automobile catalytic converters. However, an environmental time series of Os concentrations and isotopic composition spanning the pre-industrial to modern era has not previously been developed to evaluate changes in atmospheric Os sources through time. Here we present the first measurements of Os concentration and isotopic composition (to our knowledge) in a 100 m-long ice core collected from Summit, Greenland, spanning from ca. 1700 to 2010 AD. Due to the extremely low Os concentrations in snow (10-15 g/g), these analyses have only recently become possible with advances in Thermal Ionization Mass Spectrometry (TIMS) and ultra-clean analytical procedures. Initial results indicate that the 187Os/188Os of Greenland snow was unradiogenic (187Os/188Os = 0.13-0.15) for at least several periods over the past 300 years, including both pre-anthropogenic and modern times. Os concentrations in the Summit ice core are relatively high (11-52 pg/kg) compared to previously measured precipitation in North America, Europe, Asia and Antarctic sea ice (0.35-23 pg/kg). The low (unradiogenic) isotopic composition are consistent with extraterrestrial (cosmic dust and meteorites; 187Os/188Os = 0.13) and possibly volcanic (187Os/188Os = 0.15-0.6) Os sources, although the Os isotopic composition of volcanic emissions is poorly constrained

  15. Magnesium isotope compositions of Solar System materials determined by double spiking

    Science.gov (United States)

    Hin, R.; Lai, Y. J.; Coath, C.; Elliott, T.

    2015-12-01

    As a major element, magnesium is of interest for investigating large scale processes governing the formation and evolution of rocky planetary bodies. Determining the Mg isotope composition of the Earth and other planetary bodies has hence been a topic of interest ever since mass-dependent fractionation of 'non-traditional' stable isotopes has been used to study high-temperature processes. Published results, however, suffer from disagreement on the Mg isotope compositions of the Earth and chondrites [1-5], which is attributed to residual matrix effects. Nonetheless, most recent studied have converged towards a homogeneous (chondritic) Mg isotope composition in the Solar System [2-5]. However, in several of the recent studies there is a hint of a systematic difference of about 0.02-0.06‰ in the 26Mg/24Mg isotope compositions of chondrites and Earth. Such difference, however, is only resolvable by taking standard errors, which assumes robust data for homogenous sample sets. The discrepancies between various studies unfortunately undermine the confidence in such robustness and homogeneity. The issues with matrix effects during isotopic analyses can be overcome by using a double spike approach. Such methodology generally requires three isotope ratios to solve for three unknowns, a requirement that cannot be met for Mg. However, using a newly developed approach, we present Mg isotope compositions obtained by critical mixture double spiking. This new approach should allow greater confidence in the robustness of the data and hence enable improvement of. Preliminary data indicate that chondrites have a resolvable ~0.04‰ lighter 26Mg/24Mg than (ultra)mafic rocks from Earth, Mars and the eucrite parent body, which appear indistinguishable from each other. It seems implausible that this difference is caused by magmatic process such as partial melting or crystallisation. More likely, Mg isotopes are fractionated by a non-magmatic process during the formation of planets, e

  16. Chemical composition and fatty acid contents in farmed freshwater prawns

    Directory of Open Access Journals (Sweden)

    Carolina de Gasperi Portella

    2013-08-01

    Full Text Available The objective of this work was to evaluate the chemical composition and fatty acid contents of Amazonian and giant river prawns. After four-month farming, with the same diet for both species, palmitic and stearic acids were the main saturated fatty acids. Oleic acid was the main monounsatured fatty acid, and the eicosapentaenoic and docosahexaenoic acids were the most abundant polyunsaturated acids. Amazonian prawn has higher levels of protein and polyunsaturated fatty acids than those of the giant river prawn, which shows its potential for aquaculture.

  17. Silicon isotope fractionation by marine sponges and the reconstruction of the silicon isotope composition of ancient deep water

    Science.gov (United States)

    de La Rocha, Christina L.

    2003-05-01

    The silicon isotope composition (δ30Si) of biogenic opal provides a view of the silica cycle at times in the past. Reconstructions require the knowledge of silicon isotope fractionation during opal biomineralization. The δ30Si of specimens of hexactinellid sponges and demosponges growing in the modern ocean ranged from -1.2‰ to -3.7‰ (n = 6), corresponding to the production of opal that has a δ30Si value 3.8‰ ± 0.8‰ more negative than seawater silicic acid and a fractionation factor (α) of 0.9964. This is three times the fractionation observed during opal formation by marine diatoms and terrestrial plants and is the largest fractionation of silicon isotopes observed for any natural process on Earth. The δ30Si values of sponge spicules across the Eocene-Oligocene boundary at Ocean Drilling Program Site 689 on Maud Rise range from -1.1‰ to -3.0‰, overlapping the range observed for sponges growing in modern seawater.

  18. Temperature evolution and the oxygen isotope composition of Phanerozoic oceans from carbonate clumped isotope thermometry

    Science.gov (United States)

    Henkes, Gregory A.; Passey, Benjamin H.; Grossman, Ethan L.; Shenton, Brock J.; Yancey, Thomas E.; Pérez-Huerta, Alberto

    2018-05-01

    Surface temperature is among the most important parameters describing planetary climate and habitability, and yet there remains considerable debate about the temperature evolution of the Earth's oceans during the Phanerozoic Eon (541 million years ago to present), the time during which complex metazoan life radiated on Earth. Here we critically assess the emerging record of Phanerozoic ocean temperatures based on carbonate clumped isotope thermometry of fossil brachiopod and mollusk shells, and we present new data that fill important gaps in the Late Paleozoic record. We evaluate and reject the hypothesis that solid-state reordering of 13C-18O bonds has destroyed the primary clumped isotope temperature signal of most fossils during sedimentary burial at elevated temperatures. The resulting Phanerozoic record, which shows a general coupling between tropical seawater temperatures and atmospheric carbon dioxide (CO2) levels since the Paleozoic, indicates that tropical temperatures during the icehouse climate of the Carboniferous period were broadly similar to present (∼25-30 °C), and suggests that benthic metazoans were able to thrive at temperatures of 35-40 °C during intervals of the early and possibly the latest Paleozoic when CO2 levels were likely 5-10× higher than present-day values. Equally important, there is no resolvable trend in seawater oxygen isotope ratios (δ18 O) over the past ∼500 million years, indicating that the average temperature of oxygen exchange between seawater and the oceanic crust has been high (∼270 °C) since at least the early Paleozoic, which points to mid-ocean ridges as the dominant locus of water-rock interaction over the past half-billion years.

  19. Stable water isotopic composition of the Antarctic subglacial Lake Vostok: implications for understanding the lake's hydrology.

    Science.gov (United States)

    Ekaykin, Alexey A; Lipenkov, Vladimir Y; Kozachek, Anna V; Vladimirova, Diana O

    2016-01-01

    We estimated the stable isotopic composition of water from the subglacial Lake Vostok using two different sets of samples: (1) water frozen on the drill bit immediately after the first lake unsealing and (2) water frozen in the borehole after the unsealing and re-drilled one year later. The most reliable values of the water isotopic composition are: -59.0 ± 0.3 ‰ for oxygen-18, -455 ± 1 ‰ for deuterium and 17 ± 1 ‰ for d-excess. This result is also confirmed by the modelling of isotopic transformations in the water which froze in the borehole, and by a laboratory experiment simulating this process. A comparison of the newly obtained water isotopic composition with that of the lake ice (-56.2 ‰ for oxygen-18, -442.4 ‰ for deuterium and 7.2 ‰ for d-excess) leads to the conclusion that the lake ice is very likely formed in isotopic equilibrium with water. In turn, this means that ice is formed by a slow freezing without formation of frazil ice crystals and/or water pockets. This conclusion agrees well with the observed physical and chemical properties of the lake's accreted ice. However, our estimate of the water's isotopic composition is only valid for the upper water layer and may not be representative for the deeper layers of the lake, so further investigations are required.

  20. An IBM-1620 code for calculaton of isotopic composition of irradiated uranium (ISOCOM-1)

    International Nuclear Information System (INIS)

    Soliman, R.H.; Karchava, G.; Hamouda, I.

    1974-01-01

    The present work gives a description of an IBM-1620 code to calculate the isotopic composition during the irradiation of a nuclear fuel, which initially consists of 235 U and 238 U. The numerical results of test calculations as well as the ET-RR-1 reactor calculations are presented. The code is in operation since 1968

  1. Soil moisture effects on the carbon isotope composition of soil respiration

    Science.gov (United States)

    Claire L. Phillips; Nick Nickerson; David Risk; Zachary E. Kayler; Chris Andersen; Alan Mix; Barbara J. Bond

    2010-01-01

    The carbon isotopic composition (δ13C) of recently assimilated plant carbon is known to depend on water-stress, caused either by low soil moisture or by low atmospheric humidity. Air humidity has also been shown to correlate with the δ13C of soil respiration, which suggests indirectly that recently fixed photosynthates...

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

    International Nuclear Information System (INIS)

    Holden, N.E.

    1993-01-01

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

  3. Interpretation of groundwater origin in the Velenje coal mine on the basis of isotope composition

    Directory of Open Access Journals (Sweden)

    Janko Urbanc

    2002-12-01

    Full Text Available The aim of the investigation was to determine the isotopic properties of cave waters from the Velenje coal mine and define the recharge areas of individual aquifers. With regard to the oxygen isotope composition, groundwater in the Velenje coal mine can beclassified into three types. Typical d18O values of the first type are around -9 ‰ and are found in surface waters in the vicinity of the mine, therefore it is supposed that these waters are recharged locally. The second type is represented mainly by waters from thelower part of the pliocene aquifer. The average oxygen composition of these waters is about -11 ‰. This isotope composition is considerably different from the isotope composition of recent waters from the mine’s vicinity, which leads to the conclusion that these are older, fossile waters. These waters also have a very high degree of mineralization and consequently conductivity. Waters of the third type have average δ18O values around -10 ‰ and originate mainly from triassic dolomites. These waters could be a mixture of recentand old waters, but it is also possible that they flow into the coal mine from the higher areas of Paški Kozjak.

  4. Oxygenation of a Cryogenian ocean (Nanhua Basin, South China) revealed by pyrite Fe isotope compositions

    Science.gov (United States)

    Zhang, Feifei; Zhu, Xiangkun; Yan, Bin; Kendall, Brian; Peng, Xi; Li, Jin; Algeo, Thomas J.; Romaniello, Stephen

    2015-11-01

    The nature of ocean redox chemistry between the Cryogenian Sturtian and Marinoan glaciations (ca. 663-654 Ma) is important for understanding the relationship between environmental conditions and the subsequent emergence and expansion of early animals. The Cryogenian-to-Ediacaran stratigraphic succession of the Nanhua Basin in South China provides a nearly complete sedimentary record of the Cryogenian, including a continuous record of interglacial sedimentation. Here, we present a high-resolution pyrite Fe isotope record for a ∼120-m-long drill-core (ZK105) through Sturtian glacial diamictites and the overlying interglacial sediments in the Nanhua Basin to explore changes in marine chemistry during the late Cryogenian. Our pyrite Fe isotope profile exhibits significant stratigraphic variation: Interval I, comprising middle to upper Tiesi'ao diamictites (correlative with the Sturtian glaciation), is characterized by light, modern seawater-like Fe isotope compositions; Interval II, comprising uppermost Tiesi'ao diamictites and the basal organic-rich Datangpo Formation, is characterized by an abrupt shift to heavier Fe isotope compositions; and Interval III, comprising organic-poor grey shales in the middle Datangpo Formation, is characterized by the return of lighter, seawater-like Fe isotope compositions. We infer that Interval I pyrite was deposited in a predominantly anoxic glacial Nanhua Basin through reaction of dissolved Fe2+ and H2S mediated by microbial sulfate reduction (MSR). The shift to heavier pyrite Fe isotope values in Interval II is interpreted as partial oxidation of ferrous iron to ferric iron and subsequent near-quantitative reduction and transformation of Fe-oxyhydroxides to pyrite through coupling with oxidation of organic matter in the local diagenetic environment. In Interval III, near-quantitative oxidation of ferrous iron to Fe-oxyhydroxides followed by near-quantitative reduction and conversion to pyrite in the local diagenetic environment

  5. Determination of the isotopic composition of natural and slightly enriched uranium by alpha-spectrometry

    DEFF Research Database (Denmark)

    Kunzendorf, Helmar

    1968-01-01

    Determinations of the isotope contents of 238U, 235U and 234U in five uranium samples containing 0–5 at% 235U were carried out on the basis of a least-squares fit of the α-spectra from the samples, measured with a semiconductor detector, to the theoretically expected α-spectra. With a simple source...

  6. Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

    Science.gov (United States)

    Voss, Britta; Wickland, Kimberly P.; Aiken, George R.; Striegl, Robert G.

    2017-01-01

    Riverine ecosystems receive organic matter (OM) from terrestrial sources, internally produce new OM, and biogeochemically cycle and modify organic and inorganic carbon. Major gaps remain in the understanding of the relationships between carbon sources and processing in river systems. Here we synthesize isotopic, elemental, and molecular properties of dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the Upper Mississippi River (UMR) system above Wabasha, MN, including the main stem Mississippi River and its four major tributaries (Minnesota, upper Mississippi, St. Croix, and Chippewa Rivers). Our goal was to elucidate how biological processing modifies the chemical and isotopic composition of aquatic carbon pools during transport downstream in a large river system with natural and man-made impoundments. Relationships between land cover and DOC carbon-isotope composition, absorbance, and hydrophobic acid content indicate that DOC retains terrestrial carbon source information, while the terrestrial POC signal is largely replaced by autochthonous organic matter, and DIC integrates the influence of in-stream photosynthesis and respiration of organic matter. The UMR is slightly heterotrophic throughout the year, but pools formed by low-head navigation dams and natural impoundments promote a shift towards autotrophic conditions, altering aquatic ecosystem dynamics and POC and DIC composition. Such changes likely occur in all major river systems affected by low-head dams and need to be incorporated into our understanding of inland water carbon dynamics and processes controlling CO2 emissions from rivers, as new navigation and flood control systems are planned for future river and water resources management.

  7. Measurement of the isotopic composition of dissolved iron in the open ocean

    Science.gov (United States)

    Lacan, F.; Radic, A.; Jeandel, C.; Poitrasson, F.; Sarthou, G.; Pradoux, C.; Freydier, R.

    2008-12-01

    This work demonstrates for the first time the feasibility of the measurement of the isotopic composition of dissolved iron in seawater for a typical open ocean Fe concentration range (0.1-1 nM). It also presents the first data of this kind. Iron is preconcentrated using a Nitriloacetic Acid Superflow resin and purified using an AG1x4 anion exchange resin. The isotopic ratios are measured with a MC-ICPMS Neptune, coupled with a desolvator (Aridus II), using a 57Fe-58Fe double spike mass bias correction. Measurement precision (0.13‰, 2SD) allows resolving small iron isotopic composition variations within the water column, in the Atlantic sector of the Southern Ocean (from δ 57Fe = -0.19 to +0.32‰). Isotopically light iron found in the Upper Circumpolar Deep Water is hypothesized to result from organic matter remineralization. Shallow samples suggest that, if occurring, an iron isotopic fractionation during iron uptake by phytoplankton is characterized by a fractionation factor, such as: |Δ57Fe(plankton-seawater)| < 0.48‰.

  8. Methane Carbon Isotopic Composition Reveals Changing Production Pathways Across a Gradient of Permafrost Thaw

    Science.gov (United States)

    Rocci, K.; Burke, S. A.; Clariza, P.; Malhotra, A.; McCalley, C. K.; Verbeke, B. A.; Werner, S. L.; Roulet, N. T.; Varner, R. K.

    2017-12-01

    Methane (CH4) emission in areas of discontinuous permafrost may increase with warming temperatures resulting in a positive feedback to climate change. Characterizing the production pathways of CH4, which may be inferred by measuring carbon isotopes, can help determine underlying mechanistic changes. We studied CH4 flux and isotopic composition of porewater (δ13C-CH4) in a sub-arctic peatland in Abisko, Sweden to understand controls on these factors across a thaw gradient during four growing seasons. Methane chamber flux measurements and porewater samples were collected in July 2013, and over the growing seasons of 2014 to 2016. Samples were analyzed on a Gas Chromatograph with a Flame Ionization Detector for CH4 concentrations and a Quantum Cascade Laser for carbon isotopes. Increased emission rates and changing isotopic signatures were observed across the thaw gradient throughout the growing season. While CH4 flux increased with increases in temperature and shallower water table, δ13C-CH4 exhibited a seasonal pattern that did not correlate with measured environmental variables, suggesting dependence on other factors. The most significant controlling factor for both flux and isotopic signature was plant community composition, specifically, the presence of graminoid species. Graminoid cover increases with thaw stage so both CH4 emissions and δ13C-CH4 are likely to increase in a warmer world, suggesting a shift toward the acetoclastic pathway of methane production.

  9. Oxygen and nitrogen isotopic composition of nitrate in commercial fertilizers, nitric acid, and reagent salts.

    Science.gov (United States)

    Michalski, Greg; Kolanowski, Michelle; Riha, Krystin M

    2015-01-01

    Nitrate is a key component of synthetic fertilizers that can be beneficial to crop production in agro-ecosystems, but can also cause damage to natural ecosystems if it is exported in large amounts. Stable isotopes, both oxygen and nitrogen, have been used to trace the sources and fate of nitrate in various ecosystems. However, the oxygen isotope composition of synthetic and organic nitrates is poorly constrained. Here, we present a study on the N and O isotope composition of nitrate-based fertilizers. The δ(15)N values of synthetic and natural nitrates were 0 ± 2 ‰ similar to the air N2 from which they are derived. The δ(18)O values of synthetic nitrates were 23 ± 3 ‰, similar to air O2, and natural nitrate fertilizer δ(18)O values (55 ± 5 ‰) were similar to those observed in atmospheric nitrate. The Δ(17)O values of synthetic fertilizer nitrate were approximately zero following a mass-dependent isotope relationship, while natural nitrate fertilizers had Δ(17)O values of 18 ± 2 ‰ similar to nitrate produced photochemically in the atmosphere. These narrow ranges of values can be used to assess the amount of nitrate arising from fertilizers in mixed systems where more than one nitrate source exists (soil, rivers, and lakes) using simple isotope mixing models.

  10. Inventory Assessment of Pin-wise Isotopic Composition in the Spent Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Zafar, Zafar Iqbal; Kim, Myung Hyun [Kyung Hee University, Yongin (Korea, Republic of)

    2016-05-15

    There is no direct method to determine the pin-wise composition in a reasonable time frame, so, different multifaceted attempts have been made to calculate isotopic distribution of the SNF under special circumstances. There are numerous factors that influence the final SNF composition; initial fuel composition (especially enrichment), operating conditions of the reactor and final burnup imparted to the fuel, to name a few. An assumption, usually employed implicitly, is that the SNF composition is a function of the burnup and the initial enrichment only. Current methodology can be utilized by making use of the three code strategy i.e. (HELIOS 1.5, MASTER 2.2, and ORIGEN2) to assess the amount of the isotopes that are hazardous for being radioactive as well as those ones that have some role (positive or negative) in reactivity variations inside the core. Effect of the operating power i.e. dominant neutron flux is also incorporated. The minor spectrum variation from BOC to the EOC could be neglected because PWR assemblies are adorned in a way to make the neutron spectrum uniform over the core; (2) minor variation of the neutron spectrum has very little effect on the SNF composition. Few isotopes like Cs-135, Pu-241, etc. show remarkable dependence on the reactor operating conditions (e.g. operating power level) while many important isotopes like U-235, I-129, Cs-137, etc. depend on the net burnup imparted to the fuel only. Detailed pin-wise isotopic composition of the spent nuclear fuel from PWRs could be ascertained if influence of all of the concerned parameters is considered precisely. Here, we considered effect of the burnup on the composition of a selected fuel pin from the assembly B-7. Effect of the operating power level (i.e. flux) is accounted implicitly. This technique of composition reconstruction utilizes the pin-wise burnup calculation capability of the core analysis code MASTER 2.2. The relative magnitudes of the considered isotopes from two different

  11. 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.

  12. Constraints on Phanerozoic paleotemperature and seawater oxygen isotope evolution from the carbonate clumped isotope compositions of Late Paleozoic marine fossils (Invited)

    Science.gov (United States)

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

    2013-12-01

    A long-standing geoscience controversy has been the interpretation of the observed several per mil increase in the oxygen isotope compositions of marine calcites over the Phanerozoic Eon. Explanations for this trend have included decreasing seawater paleotemperatures, increasing seawater oxygen isotope values, and post-depositional calcite alteration. Carbonate clumped isotope paleothermometry is a useful geochemical tool to test these hypotheses because of its lack of dependence on the bulk isotopic composition of the water from which carbonate precipitated. This technique is increasingly applied to ancient marine invertebrate shells, which can be screened for diagenesis using chemical and microstructural approaches. After several years of clumped isotope analysis of these marine carbonates in a handful of laboratories, a long-term temperature and isotopic trend is emerging, with the results pointing to relatively invariant seawater δ18O and generally decreasing seawater temperatures through the Phanerozoic. Uncertainties remain, however, including the effects of reordering of primary clumped isotope compositions via solid-state diffusion of C and O through the mineral lattice at elevated burial temperatures over hundred million year timescales. To develop a quantitative understanding of such reordering, we present data from laboratory heating experiments of late Paleozoic brachiopod calcite. When combined with kinetic models of the reordering reaction, the results of these experiments suggest that burial temperatures less than ~120 °C allow for preservation of primary brachiopod clumped isotope compositions over geological timescales. Analyses of well-preserved Carboniferous and Permian brachiopods reinforce these results by showing that shells with apparent clumped isotope temperatures of ~150 °C are associated with deep sedimentary burial (>5 km), whereas those with putatively primary paleotemperatures in the 10-30 °C range experienced no more than ~1.5 km

  13. Chemistry and isotopic composition of precipitation and surface waters in Khumbu valley (Nepal Himalaya): N dynamics of high elevation basins.

    Science.gov (United States)

    Balestrini, Raffaella; Polesello, Stefano; Sacchi, Elisa

    2014-07-01

    We monitored the chemical and isotopic compositions of wet depositions, at the Pyramid International Laboratory (5050 ma.s.l.), and surrounding surface waters, in the Khumbu basin, to understand precipitation chemistry and to obtain insights regarding ecosystem responses to atmospheric inputs. The major cations in the precipitation were NH4(+) and Ca(2+), whereas the main anion was HCO3(-), which constituted approximately 69% of the anions, followed by NO3(-), SO4(2-) and Cl(-). Data analysis suggested that Na(+), Cl(-) and K(+) were derived from the long-range transport of marine aerosols. Ca(2+), Mg(2+) and HCO3(-) were related to rock and soil dust contributions and the NO3(-) and SO4(2-) concentrations were derived from anthropogenic sources. Furthermore, NH4(+) was derived from gaseous NH3 scavenging. The isotopic composition of weekly precipitation ranged from -1.9 to -23.2‰ in δ(18)O, and from -0.8 to -174‰ in δ(2)H, with depleted values characterizing the central part of the monsoon period. The chemical composition of the stream water was dominated by calcite and/or gypsum dissolution. However, the isotopic composition of the stream water did not fully reflect the composition of the monsoon precipitation, which suggested that other water sources contributed to the stream flow. Precipitation contents for all ions were the lowest ones among those measured in high elevation sites around the world. During the monsoon periods the depositions were not substantially influenced by anthropogenic inputs, while in pre- and post-monsoon seasons the Himalayas could not represent an effective barrier for airborne pollution. In the late monsoon phase, the increase of ionic contents in precipitation could also be due to a change in the moisture source. The calculated atmospheric N load (0.30 kg ha(-1) y(-1)) was considerably lower than the levels that were measured in other high-altitude environments. Nevertheless, the NO3(-) concentrations in the surface waters

  14. Chemistry and isotopic composition of precipitation and surface waters in Khumbu valley (Nepal Himalaya): N dynamics of high elevation basins

    International Nuclear Information System (INIS)

    Balestrini, Raffaella; Polesello, Stefano; Sacchi, Elisa

    2014-01-01

    We monitored the chemical and isotopic compositions of wet depositions, at the Pyramid International Laboratory (5050 m a.s.l.), and surrounding surface waters, in the Khumbu basin, to understand precipitation chemistry and to obtain insights regarding ecosystem responses to atmospheric inputs. The major cations in the precipitation were NH 4 + and Ca 2+ , whereas the main anion was HCO 3 − , which constituted approximately 69% of the anions, followed by NO 3 − , SO 4 2− and Cl − . Data analysis suggested that Na + , Cl − and K + were derived from the long-range transport of marine aerosols. Ca 2+ , Mg 2+ and HCO 3 − were related to rock and soil dust contributions and the NO 3 − and SO 4 2− concentrations were derived from anthropogenic sources. Furthermore, NH 4 + was derived from gaseous NH 3 scavenging. The isotopic composition of weekly precipitation ranged from − 1.9 to − 23.2‰ in δ 18 O, and from − 0.8 to − 174‰ in δ 2 H, with depleted values characterizing the central part of the monsoon period. The chemical composition of the stream water was dominated by calcite and/or gypsum dissolution. However, the isotopic composition of the stream water did not fully reflect the composition of the monsoon precipitation, which suggested that other water sources contributed to the stream flow. Precipitation contents for all ions were the lowest ones among those measured in high elevation sites around the world. During the monsoon periods the depositions were not substantially influenced by anthropogenic inputs, while in pre- and post-monsoon seasons the Himalayas could not represent an effective barrier for airborne pollution. In the late monsoon phase, the increase of ionic contents in precipitation could also be due to a change in the moisture source. The calculated atmospheric N load (0.30 kg ha −1 y −1 ) was considerably lower than the levels that were measured in other high-altitude environments. Nevertheless, the NO 3

  15. Regulation of Isotopic Composition of Water - way of Improvement of Cosmonauts Drinking Water Functional Properties

    Science.gov (United States)

    Kulikova, Ekaterina; Utina, Dina; Vorozhtsova, Svetlana; Severyuhin, Yuri; Abrosimova, Anna; Sinyak, Yuri; Ivanov, Alexander

    The problem in providing drinking water to cosmonauts is solved - at this moment there is a task to improve the functional properties of the water. One of the perspectives of this trend is the use of light isotopic water. The animal studies have shown that long-term consumption of water with a depletion of deuterium and oxygen heavy isotopes accelerates the rise of mass non-irradiated mice, the phase fluctuations reducing or increasing hematological parameters were having adaptive nature. These fluctuations didn’t overcome values beyond the physiological norm of this type of animal. It is established that the therapeutic use of light isotopic water with 35 - 90 ppm in deuterium increases the survival of irradiated mice by an average of 30%, contributes to the preservation of irradiated animals body weight. Treatment of acute radiation sickness with light isotopic water stimulates hematopoietic recovery. At the same time, keeping mice drinking light isotopic water for 7 - 8 days before the irradiation (from 4 to 8.5 Gr) has no effect on the level of radio resistance. Longer keeping mice on light isotopic water, for 14 -21 days - reduction in life expectancy, animal mass, bone marrow cellularity and the level of white blood cells in irradiated animals is noted. It was established that keeping mice on light isotopic water for 14 days before exposure in experimental animals causes an increase in the mitotic index and the frequency of formation of aberrant mitosis after 24 hours of Co(60) gamma radiation in doses of 1 , 2, and 4 Gr. Thus, it is clear that the regulation of the isotopic composition of drinking water - way to improve its functional properties.

  16. The influence of traffic and wood combustion on the stable isotopic composition of carbon monoxide

    Directory of Open Access Journals (Sweden)

    M. Saurer

    2009-05-01

    Full Text Available Carbon monoxide in the atmosphere is originating from various combustion and oxidation processes. Recently, the proportion of CO resulting from the combustion of wood for domestic heating may have increased due to political measures promoting this renewable energy source. Here, we used the stable isotope composition of CO (δ13C and δ18O for the characterization of different CO sources in Switzerland, along with other indicators for traffic and wood combustion (NOx-concentration, aerosol light absorption at different wavelengths. We assessed diurnal variations of the isotopic composition of CO at 3 sites during winter: a village site dominated by domestic heating, a site close to a motorway and a rural site. The isotope ratios of wood combustion emissions were studied at a test facility, indicating significantly lower δ18O of CO from wood combustion compared to traffic emissions. At the village and the motorway site, we observed very pronounced diurnal δ18O-variations of CO with an amplitude of up to 8‰. Solving the isotope mass balance equation for three distinct sources (wood combustion, traffic, clean background air resulted in diurnal patterns consistent with other indicators for wood burning and traffic. The average night-time contribution of wood-burning to total CO was 70% at the village site, 49% at the motorway site and 29% at the rural site based on the isotope mass balance. The results, however, depend strongly on the pure source isotope values, which are not very well known. We therefore additionally applied a combined CO/NOx-isotope model for verification. Here, we separated the CO emissions into different sources based on distinct CO/NOx emissions ratios for wood combustion and traffic, and inserted this information in the isotope mass balance equation. Accordingly, a highly significant agreement between measured and calculated δ18

  17. Chemical and Oxygen Isotopic Composition of Roman and Late Antique Glass from Northern Greece

    Directory of Open Access Journals (Sweden)

    Alberta Silvestri

    2017-01-01

    Full Text Available The present paper emphasizes the importance of measuring the oxygen isotopic and chemical compositions of ancient glass, in order to constrain some features such as age, raw materials, and production technologies and to identify the “fingerprint” of local productions. In this context, thirty-nine Roman and late Antique glass samples and eight chert samples from northern Greece were selected and analysed for their oxygen isotopic and chemical compositions. Results show that the majority of glass samples are produced using natron as flux and have δ18O values of about 15.5‰, plus or minus a few tenths of one per mil, suggesting that raw materials probably come from Levantine area. Four samples are heavily enriched in 18O, and their chemical composition clearly shows that they were made with soda plant ash as flux. Isotopic and chemical data of Greek chert samples support the hypothesis of local production of the above samples. About half of the glass samples have chemical compositions, which allow their age to be constrained to the late Antique period. For the remaining glass, similarities with literature compositional groups are reported and discussed.

  18. Mineralogy and Oxygen Isotope Compositions of Two C-Rich Hydrated Interplanetary Dust Particles

    Science.gov (United States)

    Snead, C. J.; McKeegan, K. D.; Messenger, S.; Nakamura-Messenger, K.

    2012-01-01

    Oxygen isotopic compositions of chondrites reflect mixing between a O-16-rich reservoir and a O-17,O-18-rich reservoir produced via mass-independent fractionation. The composition of the O-16-rich reservoir is reasonably well constrained, but material representing the O-17,O-18-rich end-member is rare. Self-shielding models predict that cometary water, presumed to represent this reservoir, should be enriched in O-17 and O-18 18O by > 200%. Hydrated interplanetary dust particles (IDPs) rich in carbonaceous matter may be derived from comets; such particles likely contain the products of reaction between O-16-poor water and anhydrous silicates that formed in the inner solar system. Here we present mineralogy and oxygen isotope compositions of two C-rich hydrated IDPs, L2083E47 and L2071E35.

  19. Preservation of Earth-forming events in the tungsten isotopic composition of modern flood basalts

    Science.gov (United States)

    Rizo, Hanika; Walker, Richard J.; Carlson, Richard W.; Horan, Mary F.; Mukhopadhyay, Sujoy; Manthos, Vicky; Francis, Don; Jackson, Matthew G.

    2016-05-01

    How much of Earth's compositional variation dates to processes that occurred during planet formation remains an unanswered question. High-precision tungsten isotopic data from rocks from two large igneous provinces, the North Atlantic Igneous Province and the Ontong Java Plateau, reveal preservation to the Phanerozoic of tungsten isotopic heterogeneities in the mantle. These heterogeneities, caused by the decay of hafnium-182 in mantle domains with high hafnium/tungsten ratios, were created during the first ~50 million years of solar system history, indicating that portions of the mantle that formed during Earth’s primary accretionary period have survived to the present.

  20. Primary and diagenetic controls of isotopic compositions of iron-formation carbonates

    Science.gov (United States)

    Kaufman, Alan J.; Hayes, J. M.; Klein, C.

    1990-01-01

    Results are presented on parallel analyses of carbonate and chert microbands in segments from the early Proterozoic Dales Gorge Member of the Brockman Iron Formation (western Australia), including data on isotopic, chemical, and mineralogic variations in microbanded carbonates, cherts, and coexisting minerals in four core segments from Paraburdoo and one from Wittenoom. It is shown that patterns of variation observed in isotopic abundance and mineral composition can be consistently explained in terms of diagenetic replacement of fine-grained primary precipitates by secondary ones, rather than by mineral-dependent fractionations, metamorphism, or the influence of large volumes of water in an open system.

  1. Oxigen isotope compositions as indicators of epidote granite genesis in the Borborema Provinces, NE Brazil

    International Nuclear Information System (INIS)

    Ferreira, V.P.; Valley, J.W; Sial, A.N; Spicuzza, M.J

    2001-01-01

    Neoproterozoic magmatic epidote-bearing granitoids intrude low-grade metapelites in the Cachoeirinha-Salgueiro terrane (CST), and gneisses and migmatites in the Serido terrane (ST), in the Borborema structural province, northeastern Brazil. Granitoids in both terranes contain biotite and hornblende, and are metaluminous, calc-alkalic, and oxidized I-type granites according to White's (1992) classification. However, in spite of these similarities, this work shows that mineral oxygen isotope data from plutons of the two terranes indicate different magma sources, and that magmatic epidote besides crystallizing at different pressure conditions, can have variable isotopic composition (au)

  2. Measurement of the isotopic composition of galactic cosmic ray carbon, nitrogen and oxygen

    International Nuclear Information System (INIS)

    Wiedenbeck, M.E.; Greiner, D.E.; Bieser, F.S.; Crawford, H.J.; Heckman, H.H.; Lindstrom, P.J.

    1979-06-01

    The results of an investigation of the isotopic composition of galactic cosmic ray carbon, nitrogen and oxygen (E approx. 80 to 230 MeV/amu) made using the U.C. Berkeley HKH instrument aboard the ISEE-3 spacecraft are reported. The combination of high mass resolution and a large statistical sample makes possible a precise determination of the relative isotopic abundances for these elements. In local interplanetary space we find: 13 C/C = 0.067 +- 0.008, 15 N/N = 0.54 +- 0.03, 17 O/O 18 O/O = 0.019 +- 0.003

  3. A measurement of the isotopic composition of galactic cosmic ray carbon, nitrogen and oxygen

    Science.gov (United States)

    Wiedenbeck, M. E.; Greiner, D. E.; Bieser, F. S.; Crawford, H. J.; Heckman, H. H.; Lindstrom, P. J.

    1980-01-01

    The paper reports the results of an investigation of the isotopic composition of galactic cosmic ray carbon, nitrogen and oxygen (80-230 MeV/amu) made using the U.C. Berkeley HKH instrument aboard the ISEE-3 spacecraft. The combination of high mass resolution and a large statistical sample makes possible a precise determination of the relative isotopic abundances for these elements. In local interplanetary space the following values are found: C-13/C = 0.067 + or - 0.008, N-15/N = 0.54 + or - 0.03, O-17/O less than 0.027, and O-18/O - 0.019 + or - 0.003.

  4. The Oxygen Isotopic Composition of MIL 090001: A CR2 Chondrite with Abundant Refractory Inclusions

    Science.gov (United States)

    Keller, Lindsay P.; McKeegan, K. D.; Sharp, Z. D.

    2012-01-01

    MIL 090001 is a large (>6 kg) carbonaceous chondrite that was classified as a member of the CV reduced subgroup (CVred) that was recovered during the 2009-2010 ANSMET field season [1]. Based on the abundance of refractory inclusions and the extent of aqueous alteration, Keller [2] suggested a CV2 classification. Here we report additional mineralogical and petrographic data for MIL 090001, its whole-rock oxygen isotopic composition and ion microprobe analyses of individual phases. The whole rock oxygen isotopic analyses show that MIL 090001 should be classified as a CR chondrite.

  5. Fractionation behavior of chromium isotopes during coprecipitation with calcium carbonate

    DEFF Research Database (Denmark)

    Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

    2015-01-01

    Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenviro......Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track...

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

    Science.gov (United States)

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

    2017-06-01

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

  7. Mapping Precipitation Patterns from the Stable Isotopic Composition of Surface Waters: Olympic Peninsula, Washington State

    Science.gov (United States)

    Anders, A. M.; Brandon, M. T.

    2008-12-01

    Available data indicate that large and persistent precipitation gradients are tied to topography at scales down to a few kilometers, but precipitation patterns in the majority of mountain ranges are poorly constrained at scales less than tens of kilometers. A lack of knowledge of precipitation patterns hampers efforts to understand the processes of orographic precipitation and identify the relationships between geomorphic evolution and climate. A new method for mapping precipitation using the stable isotopic composition of surface waters is tested in the Olympic Mountains of Washington State. Measured δD and δ18O of 97 samples of surface water are linearly related and nearly inseparable from the global meteoric water line. A linear orographic precipitation model extended to include in effects of isotopic fractionation via Rayleigh distillation predicts precipitation patterns and isotopic composition of surface water. Seven parameters relating to the climate and isotopic composition of source water are used. A constrained random search identifies the best-fitting parameter set. Confidence intervals for parameter values are defined and precipitation patterns are determined. Average errors for the best-fitting model are 4.8 permil in δD. The difference between the best fitting model and other models within the 95% confidence interval was less than 20%. An independent high-resolution precipitation climatology documents precipitation gradients similar in shape and magnitude to the model derived from surface water isotopic composition. This technique could be extended to other mountain ranges, providing an economical and fast assessment of precipitation patterns requiring minimal field work.

  8. Temperature and Oxygen Isotope Composition of The Ediacaran Ocean: Constraints From Clumped Isotope Carbonate Thermometry

    Science.gov (United States)

    Bonifacie, M.; Eiler, J. M.; Fike, D. A.

    2008-12-01

    The temperature and chemical variations of the early oceans on Earth are highly debated, particularly for periods associated with significant evolutionary change and/or extinction. The temperature of past oceans has been estimated based on conventional carbonate-water and/or silicate-water stable oxygen isotope thermometry. Precambrian carbonates and silicates both exhibit a long-term secular trend of increasing δ18O values with decreasing age. This trend has been used to support two opposite - though related - interpretations: the Earth's oceans gradually cooled over the course of the Proterozoic eon, from a maximum of ~ 60-90°C at ~ 2.5Ga (and were, on average, relatively warm during much of the Paleozoic era) [1]. This interpretation has been supported by Si-isotope proxies and the thermal tolerances of proteins in various classes of microbial organisms [2-3]. Alternatively, the δ18O value of the oceans has gradually increased through time [4-5], and mean Earth surface temperatures varied over a narrow range similar to modern conditions. In other terms, one either assumes an ocean of constant δ18O and infers that climate varied dramatically, or vise versa. Finally, it is possible that post- depositional processes (e.g., diagenesis, burial metamorphism, weathering) has modified the δ18O values of all or most Precambrian sedimentary carbonates and silicates, overprinting any paleoclimatic variations. Carbonate 'clumped isotope' thermometry provides a new way to independently test these hypotheses because it allows one to determine the apparent growth temperatures of carbonate minerals based on their abundances of 13C-18O bonds, as reflected by the 'Δ47' value of CO2 extracted by phosphoric acid digestion [6]. This method is thermodynamically based and independent of the δ18O of water from which the carbonate grew. We will report the initial results of measurements of 'Δ47 for a suite of carbonates from the Sultanate of Oman. This Ediacaran age (~ 635 to

  9. Isotopic composition of pyrite: Relationship to organic matter type and iron availability in some North American cretaceous shales

    Science.gov (United States)

    Gautier, D.L.

    1987-01-01

    The S isotope composition of pyrite in Cretaceous shales from the Western Interior of North America is related to organic C abundance, kerogen type and Fe availability. Both calcareous and noncalcareous rocks show a correlation between S and C, but noncalcareous rocks are relatively enriched in S with a higher S C ratio. This higher ratio probably shows that pyrite formation was Fe limited in the calcareous rocks. Organic-carbon-rich noncalcareous shales accumulated slowly beneath anoxic bottom waters. The anoxic bottom waters allowed hydrogen-rich organic matter to be preserved. Such shales have a narrow range of 34S-depleted sulfide and have Fe S ratios like stoichiometric pyrite, suggesting that pyrite formation in organic-rich shales was also limited by Fe availability. Conversely, organic-poor shales commonly accumulated at comparatively high rates, contain hydrogen-poor and refractory organic matter, and have a wide range of pyrite-S isotopic compositions. These organic-poor shales contain post-sulfidic authigenic minerals such as siderite and have excess reactive Fe rather than pyrite stoichiometry. Evidently Fe played a large role in early diagenesis and determined the course of post-sulfidic diagenesis. Fe availability was, however, mainly controlled by provenance, by the rates of sediment accumulation, and by the oxygen content of the depositional environment. ?? 1987.

  10. Determining the Importance of Microbial Processes on Gas Composition in Debris-Rich Antarctic Basal Ice Using Isotope Geochemistry

    Science.gov (United States)

    Montross, S. N.; Skidmore, M. L.; Christner, B. C.; Doyle, S. M.; Tison, J.; Samyn, D.; Sowers, T. A.

    2010-12-01

    The volume and composition of air trapped in debris-rich basal ice results not only from initial entrainment processes, but also from processes that operate in the basal zone of polar glaciers and ice sheets following entrainment. Here we report on the concentration and isotopic composition of gases in debris-rich basal ice from Taylor Glacier, Antarctica and a biological role in both gas consumption and production. Microbial cell and total dissolved solute concentrations are highest in the debris-rich facies where CO2 concentrations are also significantly elevated over atmospheric concentrations. Thawed basal ice samples amended with 14C-acetate respired this substrate at low (2oC) incubation temperatures, and the maximum respiration rate was ~10-fold higher in samples with a debris content > ~ 1% wt/vol. δ18O2 and δ13CO2 values measured are consistent with the hypothesis that changes in gas chemistry observed in the debris-rich ice, i.e. a negative correlation between CO2 and O2 concentrations, are a result of microbial respiration in the ice. This mode of respiration utilizes O2(g) to oxidize organic carbon derived from entrained debris producing CO2(g) as a metabolic byproduct. This work utilizes an isotope mass balance model to provide the first comprehensive account of the physical, chemical, and biological sources of CO2 in debris-rich basal ice.

  11. Carbon isotope composition of latex does not reflect temporal variations of photosynthetic carbon isotope discrimination in rubber trees (Hevea brasiliensis).

    Science.gov (United States)

    Kanpanon, Nicha; Kasemsap, Poonpipope; Thaler, Philippe; Kositsup, Boonthida; Gay, Frédéric; Lacote, Régis; Epron, Daniel

    2015-11-01

    Latex, the cytoplasm of laticiferous cells localized in the inner bark of rubber trees (Hevea brasiliensis Müll. Arg.), is collected by tapping the bark. Following tapping, latex flows out of the trunk and is regenerated, whereas in untapped trees, there is no natural exudation. It is still unknown whether the carbohydrates used for latex regeneration in tapped trees is coming from recent photosynthates or from stored carbohydrates, and in the former case, it is expected that latex carbon isotope composition of tapped trees will vary seasonally, whereas latex isotope composition of untapped trees will be more stable. Temporal variations of carbon isotope composition of trunk latex (δ(13)C-L), leaf soluble compounds (δ(13)C-S) and bulk leaf material (δ(13)C-B) collected from tapped and untapped 20-year-old trees were compared. A marked difference in δ(13)C-L was observed between tapped and untapped trees whatever the season. Trunk latex from tapped trees was more depleted (1.6‰ on average) with more variable δ(13)C values than those of untapped trees. δ(13)C-L was higher and more stable across seasons than δ(13)C-S and δ(13)C-B, with a maximum seasonal difference of 0.7‰ for tapped trees and 0.3‰ for untapped trees. δ(13)C-B was lower in tapped than in untapped trees, increasing from August (middle of the rainy season) to April (end of the dry season). Differences in δ(13)C-L and δ(13)C-B between tapped and untapped trees indicated that tapping affects the metabolism of both laticiferous cells and leaves. The lack of correlation between δ(13)C-L and δ(13)C-S suggests that recent photosynthates are mixed in the large pool of stored carbohydrates that are involved in latex regeneration after tapping. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  12. ISOTOPIC COMPOSITION OF HIGH SILICA RHYOLITES IN THE ...

    African Journals Online (AJOL)

    Mgina

    characterized by high silica contents (63.38 – 81.65 wt %), very low CaO (≤ 0.05 wt %), variable to unusually .... rich rocks and based on SiO2 contents, they .... SiO2. 77.3. 73.7. TiO2. 0.20. 0.40. Al2O3. 12.6. 13.5. Fe2O3. 0.53. 1.70. MnO. 0.001. 0.10. MgO. 0.33. 0.3. CaO. 0.02. 0.10. Na2O. 0.40. 1.10. K2O. 6.99. 6.90. P2O5.

  13. Changes in soil water availability in vineyards can be traced by the carbon and nitrogen isotope composition of dried wines.

    Science.gov (United States)

    Spangenberg, Jorge E; Zufferey, Vivian

    2018-04-13

    The grapevine is one of the most important edible fruit plants cultivated worldwide, and it is highly sensitive to changes in the soil water content. We studied the total carbon and nitrogen contents and stable isotope compositions (C/N WSR , δ 13 C WSR and δ 15 N WSR values) of the solid residues obtained by freeze-drying wines produced from two white grapevine cultivars (Vitis vinifera L. cv Chasselas and Petite Arvine) field grown under different soil water regimes while maintaining other climatic and ecopedological conditions identical. These experiments simulated the more frequent and extended climate change-induced periods of soil water shortage. The wines were from the 2009-2014 vintages, produced using the same vinification procedure. The plant water status, reflecting soil water availability, was assessed by the predawn leaf water potential (Ψ pd ), monitored in the field during the growing seasons. For both wine varieties, the δ 13 C WSR values are highly correlated with Ψ pd values and record the soil water availability set by soil water holding capacity, rainfall and irrigation water supply. These relationships were the same as those observed for the carbon isotope composition of fruit sugars (i.e., must sugars) and plant water status. In Chasselas wines, the nitrogen content and δ 15 N WSR values decreased with soil water deficit, indicating control of the flux of soil-water soluble nutrients into plants by soil water availability. Such a correlation was not found for Petite Arvine, probably due to different N-metabolism processes in this genetically atypical cultivar. The results presented in this study confirm and generalize what was previously found for red wine (Pinot noir); the carbon isotope composition of wine solid residues is a reliable indicator of the soil and the plant water status and thus can be used to trace back local climatic conditions in the vineyard's region. In most wines (except Petite Arvine) the C/N WSR and δ 15 N WSR

  14. High precision analysis of isotopic composition for samples used for nuclear cross-section measurements

    Directory of Open Access Journals (Sweden)

    Shibahara Yuji

    2017-01-01

    Full Text Available For the accuracy improvement of nuclear data of minor actinides and long-lived fission products in the project of “Research and development for Accuracy Improvement of neutron nuclear data on Minor Actinides”, the isotopic compositions of two Am samples (241Am sample and 243Am sample were analyzed by thermal ionization mass spectrometry. Only the peak of 241Am was observed in the analysis of 241Am sample, and level of isotopic impurities were improved from 0.1% to 0.0004%. In the analysis of 243Am sample, the peak of unreported isotope of 242mAm was observed in addition to the peaks of 243Am and 241Am. The mass spectrometry also showed that 243Am sample has other unreported impurities such as 239Pu and 240Pu.

  15. Isotopic composition of the anomalous low energy cosmic ray nitrogen and oxygen

    Science.gov (United States)

    Mewaldt, R. A.; Stone, E. C.; Vidor, S. B.; Vogt, R. E.

    1975-01-01

    The isotopic composition of the enhanced fluxes of cosmic ray nitrogen and oxygen observed below 30 MeV/nuc is of interest, whether the nuclei are a sample from some nearby galactic source region that is underabundant in carbon, or a sample of the neutral interstellar medium. Enhanced fluxes in the 6 to 12 MeV/nuc energy interval were measured over a two year period with the Caltech Electron/Isotope Spectrometer on IMP-7. The observed low-energy nitrogen and oxygen nuclei are predominantly N-14 and O-16, with upper limits (84% confidence level) of N-15/N below 0.26, O-17/0 below 0.13, and O-18/0 below 0.12 for other isotopes in the 6-12 MeV/nuc energy interval. The implications of these results for the origin of the enhanced nitrogen and oxygen fluxes are discussed.

  16. Results of the international Pu-2000 exercise for plutonium isotopic composition measurements

    International Nuclear Information System (INIS)

    Morel, J.; Bickel, M.; Hill, C.; Verbruggen, A.

    2004-01-01

    An international comparison for plutonium isotopic composition measurement, known as the Pu-2000 exercise, was organized by the ESARDA NDA-WG (European Safeguards Research and Development Association, Working Group on Techniques and Standards for Non-Destructive Assay). The aim of this comparison was to test X- and γ-ray spectrometry methods over a large range of isotopic ratios. These methods are based on the complex analysis of several X- and γ-rays in the KX region of the plutonium spectrum and also in the 120-700 keV energy range. The results obtained by the participants with their corresponding uncertainties are presented in this document and compared to the declared values. The main conclusions of the work are also given. No important bias due to an inadequate knowledge of the nuclear data for plutonium isotopes was observed

  17. Non-destructive estimates of soil carbonic anhydrase activity and associated soil water oxygen isotope composition

    Science.gov (United States)

    Jones, Sam P.; Ogée, Jérôme; Sauze, Joana; Wohl, Steven; Saavedra, Noelia; Fernández-Prado, Noelia; Maire, Juliette; Launois, Thomas; Bosc, Alexandre; Wingate, Lisa

    2017-12-01

    that this represents a robust approach to assay the activity of CA in soil. As expected, estimates of the δ18O of the soil water that equilibrates with CO2 varied in response to alteration to the δ18O of soil water. However, these estimates were consistently more negative than the composition of the soil water extracted by cryogenic vacuum distillation at the end of the gas measurements with differences of up to -3.94 ‰ VSMOW-SLAP. These offsets suggest that, at least at lower water contents, CO2-H2O isotope equilibration primarily occurs with water pools that are bound to particle surfaces and are depleted in 18O compared to bulk soil water.

  18. Lead isotopic compositions of common arsenical pesticides used in New England

    Science.gov (United States)

    Ayuso, Robert; Foley, Nora; Robinson, Gilpin; Wandless, Gregory; Dillingham, Jeremy

    2004-01-01

    The three most important arsenical pesticides and herbicides that were extensively used on apple, blueberry, and potato crops in New England from mid-1800s to recent times are lead arsenate, calcium arsenate, and sodium arsenate. Lead arsenate was probably the most heavily used of the arsenical pesticides until it was banned in 1988. Other metal-arsenic pesticides were also used but in lesser amounts. A recent report identified areas in New England where arsenical pesticides were used extensively (Robinson and Ayuso, 2004). On the basis of factor analysis of metal concentrations in stream sediment samples, a positive correlation with pesticide use was shown in regions having stream sediment sample populations that contained concentrations of high arsenic and lead. Lead isotope compositions of stream sediments from areas with heavy use of the pesticides could not be entirely explained by lead originating from rock sulfides and their weathering products. An industrial lead contribution (mostly from atmospheric deposition of lead) was suggested in general to explain the lead isotopic distributions of the stream sediments that could not be accounted for by the natural lead in the environment. We concluded that when agricultural land previously contaminated with arsenical pesticides is urbanized, pesticide residues in the soils and stream sediments could be released into the groundwater. No lead isotopic data characterizing the compositions of pesticides were available for comparison. We have determined the lead isotopic compositions of commonly used pesticides in New England, such as lead arsenate, sodium metaarsenite, and calcium arsenate, in order to assist in future isotopic comparisons and to better establish anthropogenic sources of Pb and As. New data are also presented for copper acetoarsenite (or Paris green), methyl arsonic acid and methane arsonic acid, as well as for arsanilic acid, all of which are used as feed additives to promote swine and poultry growth

  19. Uranium in open ocean: concentration and isotopic composition

    International Nuclear Information System (INIS)

    Ku, T.L.; Knauss, K.G.; Mathieu, G.G.

    1977-01-01

    Uranium concentrations and 234 U/ 238 U activity ratios have been determined in 63 seawater samples (nine vertical profiles) from the Atlantic, and Pacific, and Arctic, and the Antarctic oceans, using the alpha-spectrometric method for their determinations. Correlation between uranium and salinity is well manifested by the data from the Arctic and the Antarctic oceans, but such a relation cannot be clearly defined with the +-(1 to 2)% precision of uranium measurements for the Atlantic and Pacific data. At the 95% confidence level: (1) the uranium/salinity ratio is (9.34 + - 0.56) x 10 -8 g/g for the seawater analyzed with salinity ranging from 30.3 to 36.2 per thousand; the uranium concentration of seawater of 35 per thousand salinity is 3.3 5 + - 0.2 μ g l -1 ; (2) the 234 U/ 238 U activity ratio is 1.14 +- 0.03. Uranium isotopes in interstitial waters of the Pacific surface sediments analyzed do not show large concentration differences across the sediment-water interface as suggested by previous measurements. Current estimations of the average world river uranium concentration (0.3 to 0.6 μ g l -1 ) and 234 U/ 238 U ratio (1.2 to 1.3) and of the diffusional 234 U influx from sediments 0.3 dpm cm -2 10 -3 yr -1 ) are essentially consistent with a model which depicts a steady state distribution of uranium in the ocean. However, the 0.3 to 0.6 μ g l -1 value for river uranium may be an upper limit estimate. (author)

  20. Detection of phosphohydrolytic enzyme activity through the oxygen isotope composition of dissolved phosphate

    Science.gov (United States)

    Colman, A. S.

    2016-02-01

    Phosphohydrolytic enzymes play an important role in phosphorus remineralization. As they release phosphate (Pi) from various organophosphorus compounds, these enzymes facilitate the transfer of oxygen atoms from water to the phosphoryl moieties. Most such enzymatic reactions impart a significant isotopic fractionation to the oxygen transferred. If this reaction occurs within a cell, then the resultant oxygen isotope signal is overprinted by continued recycling of the Pi. However, if this reaction occurs extracellularly, then the isotopic signal will be preserved until the Pi is transported back into a cell. Thus, the oxygen isotope composition of Pi (δ18Op) in an aquatic ecosystem can serve as a useful indicator of the mechanisms by which P is remineralized. We develop a time-dependent model illustrating the sensitivity of the δ18O of dissolved phosphate to various modes of P remineralization. The model is informed by cell lysis experiments that reveal the relative proportions of P­i that are directly liberated from cytosol vs. regenerated from co-liberated dissolved organic phosphorus compounds via extracellular hydrolysis. By incorporating both cellular uptake and release fluxes of P, we show that the degree of isotopic disequilibrium in an aquatic ecosystem can be a strong indicator of P remineralization mode. Apparent oxygen isotope equilibrium between Pi and water arises in this model as a steady-state scenario in which fractionation upon cellular uptake of Pi counterbalances the hydrolytic source flux of disequilibrated Pi. Low and high rates of extracellular phosphohydrolase activity are shown to produce steady-state δ18Op values that are respectively above or below thermodynamic equilibrium compositions.

  1. Plutonium isotopic composition of high burnup spent fuel discharged from light water reactors

    International Nuclear Information System (INIS)

    Nakano, Yoshihiro; Okubo, Tsutomu

    2011-01-01

    Highlights: → Pu isotopic composition of fuel affects FBR core nuclear characteristics very much. → Spent fuel compositions of next generation LWRs with burnup of 70 GWd/t were obtained. → Pu isotopic composition and amount in the spent fuel with 70 GWd/t were evaluated. → Spectral shift rods of high burnup BWR increases the fissile Pu fraction of spent fuel. → Wide fuel rod pitch of high burnup PWR lowers the fissile Pu fraction of spent fuel. - Abstract: The isotopic composition and amount of plutonium (Pu) in spent fuel from a high burnup boiling water reactor (HB-BWR) and a high burnup pressurized water reactor (HB-PWR), each with an average discharge burnup of 70 GWd/t, were estimated, in order to evaluate fast breeder reactor (FBR) fuel composition in the transition period from LWRs to FBRs. The HB-BWR employs spectral shift rods and the neutron spectrum is shifted through the operation cycle. The weight fraction of fissile plutonium (Puf) isotopes to the total plutonium in HB-BWR spent fuel after 5 years cooling is 62%, which is larger than that of conventional BWRs with average burnup of 45 GWd/t, because of the spectral shift operation. The amount of Pu produced in the HB-BWR is also larger than that produced in a conventional BWR. The HB-PWR uses a wider pitch 17 x 17 fuel rod assembly to optimize neutron slowing down. The Puf fraction of HB-PWR spent fuel after 5 years cooling is 56%, which is smaller than that of conventional PWRs with average burnup of 49 GWd/t, mainly because of the wider pitch. The amount of Pu produced in the HB-PWR is also smaller than that in conventional PWRs.

  2. Isotope composition of winter precipitation and snow cover in the foothills of the Altai

    Directory of Open Access Journals (Sweden)

    N. S. Malygina

    2017-01-01

    Full Text Available Over the past three decades, several general circulation models of the atmosphere and ocean (atmospheric and oceanic general circulation models  – GCMs have been improved by modeling the hydrological cycle with the use of isotopologues (isotopes of water HDO and H2 18O. Input parameters for the GCM models taking into account changes in the isotope composition of atmospheric precipitation were, above all, the results obtained by the network GNIP – Global Network of Isotopes in Precipitation. At different times, on the vast territory of Russia there were only about 40 simultaneously functioning stations where the sampling of atmospheric precipitation was performed. In this study we present the results of the isotope composition of samples taken on the foothills of the Altai during two winter seasons of 2014/15 and 2015/16. Values of the isotope composition of precipitation changed in a wide range and their maximum fluctuations were 25, 202 and 18‰ for δ18О, dexc and δD, respectively. The weighted-mean values of δ18О and δD of the precipitation analyzed for the above two seasons were close to each other (−21.1 and −158.1‰ for the first season and −21.1 and −161.9‰ for the second one, while dexc values differed significantly. The comparison of the results of isotope analysis of the snow cover integral samples with the corresponding in the time interval the weighted-mean values of precipitation showed high consistency. However, despite the similarity of values of δ18О and δD, calculated for precipitation and snow cover, and the results, interpolated in IsoMAP (from data of the GNIP stations for 1960–2010, the dexc values were close to mean annual values of IsoMAP for only the second winter season. According to the trajectory analysis (the HYSPLIT model, the revealed differences between both, the seasons, and the long-term average values of IsoMAP, were associated with a change of main regions where the air masses

  3. Natural Ca Isotope Composition of Urine as a Rapid Measure of Bone Mineral Balance

    Science.gov (United States)

    Skulan, J.; Gordon, G. W.; Morgan, J.; Romaniello, S. J.; Smith, S. M.; Anbar, A. D.

    2011-12-01

    Naturally occurring stable Ca isotope variations in urine are emerging as a powerful tool to detect changes in bone mineral balance. Bone formation depletes soft tissue of light Ca isotopes while bone resorption releases isotopically light Ca into soft tissue. Previously published work found that variations in Ca isotope composition could be detected at 4 weeks of bed rest in a 90-day bed rest study (data collected at 4, 8 and 12 weeks). A new 30-day bed rest study involved 12 patients on a controlled diet, monitored for 7 days prior to bed rest and 7 days post bed rest. Samples of urine, blood and food were collected throughout the study. Four times daily blood samples and per void urine samples were collected to monitor diurnal or high frequency variations. An improved chemical purification protocol, followed by measurement using multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) allowed accurate and precise determinations of mass-dependent Ca isotope variations in these biological samples to better than ±0.2% (δ44/42Ca) on biomarker. Bone-specific alkaline phosphatase, a bone formation biomarker, is unchanged over this period. Ca isotopes can in principle be used to quantify net changes in bone mass. Using a mass-balance model, our results indicate an average loss of 0.62 ± 0.16 % in bone mass over the course of this 30-day study. This is consistent with the rate of bone loss in longer-term studies as seen by X-ray measurements. This Ca isotope technique should accelerate the pace of discovery of new treatments for bone disease and provide novel insights into the dynamics of bone metabolism.

  4. Isotopic composition of strontium in volcanic rocks from oahu.

    Science.gov (United States)

    Powell, J L; Delong, S E

    1966-09-09

    Analysis of several well-documented specimens from each of the three volcanic series on Oahu gives the following mean ratios of Sr(87) to Sr(86): the Waianae series, 0.7030 +/- 0.00010 (sigma); the Koolau series, 0.70385+/- 0.00009 (sigma); and the Honolulu series, 0.7029 ++/- 0.00006 ( sigma). The mean ratio of Sr(87) to Sr(86) of the Koolau series specimens is significantly higher than the means of the other two series. With one exception, significant differences in Sr(87)/ Sr(86) within a series were not found, even though some large compositional differences existed.

  5. A continuous flow isotope ratio mass spectrometry method for high precision determination of dissolved gas ratios and isotopic composition

    DEFF Research Database (Denmark)

    Charoenpong, C. N.; Bristow, L. A.; Altabet, M. A.

    2014-01-01

    Dissolved gas ratios and isotopic compositions provide essential information about the biological and physical mechanisms influencing N-2, O-2, and Ar in aquatic systems. Current methods available are either limited by overall cost, labor-intensive sample collection and analysis, or insufficient...... ratio mass spectrometer (IRMS). A continuous flow of He carrier gas completely degasses the sample, and passes through the preparation and purification system before entering the IRMS for analysis. The use of this continuous He carrier permits short analysis times (less than 8 min per sample......) as compared with current high-precision methods. In addition to reference gases, calibration is achieved using air-equilibrated water standards of known temperature and salinity. Assessment of reference gas injections, air equilibrated standards, as well as samples collected in the field shows the accuracy...

  6. Uranium isotopic composition and uranium concentration in special reference material SRM A (uranium in KCl/LiCl salt matrix)

    International Nuclear Information System (INIS)

    Graczyk, D.G.; Essling, A.M.; Sabau, C.S.; Smith, F.P.; Bowers, D.L.; Ackerman, J.P.

    1997-07-01

    To help assure that analysis data of known quality will be produced in support of demonstration programs at the Fuel Conditioning Facility at Argonne National Laboratory-West (Idaho Falls, ID), a special reference material has been prepared and characterized. Designated SRM A, the material consists of individual units of LiCl/KCl eutectic salt containing a nominal concentration of 2.5 wt. % enriched uranium. Analyses were performed at Argonne National Laboratory-East (Argonne, IL) to determine the uniformity of the material and to establish reference values for the uranium concentration and uranium isotopic composition. Ten units from a batch of approximately 190 units were analyzed by the mass spectrometric isotope dilution technique to determine their uranium concentration. These measurements provided a mean value of 2.5058 ± 0.0052 wt. % U, where the uncertainty includes estimated limits to both random and systematic errors that might have affected the measurements. Evidence was found of a small, apparently random, non-uniformity in uranium content of the individual SRM A units, which exhibits a standard deviation of 0.078% of the mean uranium concentration. Isotopic analysis of the uranium from three units, by means of thermal ionization mass spectrometry with a special, internal-standard procedure, indicated that the uranium isotopy is uniform among the pellets with a composition corresponding to 0.1115 ± 0.0006 wt. % 234 U, 19.8336 ± 0.0059 wt. % 235 U, 0.1337 ± 0.0006 wt. % 236 U, and 79.9171 ± 0.0057 wt. % 238 U

  7. Uranium isotopic composition and uranium concentration in special reference material SRM A (uranium in KCl/LiCl salt matrix)

    Energy Technology Data Exchange (ETDEWEB)

    Graczyk, D.G.; Essling, A.M.; Sabau, C.S.; Smith, F.P.; Bowers, D.L.; Ackerman, J.P.

    1997-07-01

    To help assure that analysis data of known quality will be produced in support of demonstration programs at the Fuel Conditioning Facility at Argonne National Laboratory-West (Idaho Falls, ID), a special reference material has been prepared and characterized. Designated SRM A, the material consists of individual units of LiCl/KCl eutectic salt containing a nominal concentration of 2.5 wt. % enriched uranium. Analyses were performed at Argonne National Laboratory-East (Argonne, IL) to determine the uniformity of the material and to establish reference values for the uranium concentration and uranium isotopic composition. Ten units from a batch of approximately 190 units were analyzed by the mass spectrometric isotope dilution technique to determine their uranium concentration. These measurements provided a mean value of 2.5058 {+-} 0.0052 wt. % U, where the uncertainty includes estimated limits to both random and systematic errors that might have affected the measurements. Evidence was found of a small, apparently random, non-uniformity in uranium content of the individual SRM A units, which exhibits a standard deviation of 0.078% of the mean uranium concentration. Isotopic analysis of the uranium from three units, by means of thermal ionization mass spectrometry with a special, internal-standard procedure, indicated that the uranium isotopy is uniform among the pellets with a composition corresponding to 0.1115 {+-} 0.0006 wt. % {sup 234}U, 19.8336 {+-} 0.0059 wt. % {sup 235}U, 0.1337 {+-} 0.0006 wt. % {sup 236}U, and 79.9171 {+-} 0.0057 wt. % {sup 238}U.

  8. The neodymium stable isotope composition of the silicate Earth and chondrites

    Science.gov (United States)

    McCoy-West, Alex J.; Millet, Marc-Alban; Burton, Kevin W.

    2017-12-01

    The non-chondritic neodymium (Nd) 142Nd/144Nd ratio of the silicate Earth potentially provides a key constraint on the accretion and early evolution of the Earth. Yet, it is debated whether this offset is due to the Earth being formed from material enriched in s-process Nd isotopes or results from an early differentiation process such as the segregation of a late sulfide matte during core formation, collisional erosion or a some combination of these processes. Neodymium stable isotopes are potentially sensitive to early sulfide segregation into Earth's core, a process that cannot be resolved using their radiogenic counterparts. This study presents the first comprehensive Nd stable isotope data for chondritic meteorites and terrestrial rocks. Stable Nd measurements were made using a double spike technique coupled with thermal ionisation mass spectrometry. All three of the major classes of chondritic meteorites, carbonaceous, enstatite and ordinary chondrites have broadly similar isotopic compositions allowing calculation of a chondritic mean of δ146/144Nd = -0.025 ± 0.025‰ (±2 s.d.; n = 39). Enstatite chondrites yield the most uniform stable isotope composition (Δ146/144Nd = 26 ppm), with considerably more variability observed within ordinary (Δ146/144Nd = 72 ppm) and carbonaceous meteorites (Δ146/144Nd = 143 ppm). Terrestrial weathering, nucleosynthetic variations and parent body thermal metamorphism appear to have little measurable effect on δ146/144Nd in chondrites. The small variations observed between ordinary chondrite groups most likely reflect inherited compositional differences between parent bodies, with the larger variations observed in carbonaceous chondrites being linked to varying modal proportions of calcium-aluminium rich inclusions. The terrestrial samples analysed here include rocks ranging from basaltic to rhyolitic in composition, MORB glasses and residual mantle lithologies. All of these terrestrial rocks possess a broadly similar Nd

  9. Stable chromium isotopic composition of meteorites and metal-silicate experiments: Implications for fractionation during core formation

    Science.gov (United States)

    Bonnand, P.; Williams, H. M.; Parkinson, I. J.; Wood, B. J.; Halliday, A. N.

    2016-02-01

    We present new mass independent and mass dependent Cr isotope compositions for meteorites measured by double spike thermal ionisation mass spectrometry. Small differences in both mass independent 53Cr and 54Cr relative to the Bulk Silicate Earth are reported and are very similar to previously published values. Carbonaceous chondrites are characterised by an excess in 54Cr compared to ordinary and enstatite chondrites which make mass independent Cr isotopes a useful tool for distinguishing between meteoritic groups. Mass dependent stable Cr isotope compositions for the same samples are also reported. Carbonaceous and ordinary chondrites are identical within uncertainty with average δ53 Cr values of - 0.118 ± 0.040 ‰ and - 0.143 ± 0.074 ‰ respectively. The heaviest isotope compositions are recorded by an enstatite chondrite and a CO carbonaceous chondrite, both of which have relatively reduced chemical compositions implying some stable Cr isotope fractionation related to redox processes in the circumstellar disk. The average δ53 Cr values for chondrites are within error of the estimate for the Bulk Silicate Earth (BSE) also determined by double spiking. The lack of isotopic difference between chondritic material and the BSE provides evidence that Cr isotopes were not fractionated during core formation on Earth. A series of high-pressure experiments was also carried out to investigate stable Cr isotope fractionation between metal and silicate and no demonstrable fractionation was observed, consistent with our meteorites data. Mass dependent Cr isotope data for achondrites suggest that Cr isotopes are fractionated during magmatic differentiation and therefore further work is required to constrain the Cr isotopic compositions of the mantles of Vesta and Mars.

  10. Site-specific 13C content by quantitative isotopic 13C Nuclear Magnetic Resonance spectrometry: A pilot inter-laboratory study

    International Nuclear Information System (INIS)

    Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Pagelot, Alain; Moskau, Detlef; Moreno, Aitor; Schleucher, Jürgen; Reniero, Fabiano; Holland, Margaret; Guillou, Claude; Silvestre, Virginie; Akoka, Serge; Remaud, Gérald S.

    2013-01-01

    Graphical abstract: -- Highlights: •First ring test on isotopic 13 C NMR spectrometry. •Evaluation of the intra- and inter-variability of the NMR spectrometers used. •Definition of a protocol for qualification of the performance of the spectrometer. -- Abstract: Isotopic 13 C NMR spectrometry, which is able to measure intra-molecular 13 C composition, is of emerging demand because of the new information provided by the 13 C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic 13 C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular 13 C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic 13 C NMR was then assessed on vanillin from three different origins associated with specific δ 13 C i profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ 13 C i in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results

  11. Site-specific {sup 13}C content by quantitative isotopic {sup 13}C Nuclear Magnetic Resonance spectrometry: A pilot inter-laboratory study

    Energy Technology Data Exchange (ETDEWEB)

    Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst [Firmenich SA, Corporate R and D Division, P.O. Box 239, 1211 Geneva 8 (Switzerland); Gilbert, Alexis; Yamada, Keita [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Yoshida, Naohiro [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Pagelot, Alain [Bruker Biospin SAS, 34 rue de l‘Industrie, 67166 Wissembourg Cedex (France); Moskau, Detlef; Moreno, Aitor [Bruker Biospin AG, Industriestrasse 26, 8117 Fällanden (Switzerland); Schleucher, Jürgen [Department of Medical Biochemistry and Biophysics, Umeå University, S-90187 Umeå (Sweden); Reniero, Fabiano; Holland, Margaret; Guillou, Claude [European Commission, Joint Research Centre – Institute for Health and Consumer Protection, via E. Fermi 2749, I-21027 Ispra (Italy); Silvestre, Virginie; Akoka, Serge [EBSI team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Remaud, Gérald S., E-mail: gerald.remaud@univ-nantes.fr [EBSI team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France)

    2013-07-25

    Graphical abstract: -- Highlights: •First ring test on isotopic {sup 13}C NMR spectrometry. •Evaluation of the intra- and inter-variability of the NMR spectrometers used. •Definition of a protocol for qualification of the performance of the spectrometer. -- Abstract: Isotopic {sup 13}C NMR spectrometry, which is able to measure intra-molecular {sup 13}C composition, is of emerging demand because of the new information provided by the {sup 13}C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic {sup 13}C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular {sup 13}C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic {sup 13}C NMR was then assessed on vanillin from three different origins associated with specific δ{sup 13}C{sub i} profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ{sup 13}C{sub i} in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results.

  12. Stable hydrogen, oxygen and sulfur isotopes composition in different tissues of cattle

    International Nuclear Information System (INIS)

    Sun Fengmei; Shi Guangyu; Wang Huiwen; Yang Shuming

    2012-01-01

    In order to research on stable hydrogen, oxygen, sulfur isotopes composition in different tissues of cattle, as well as the breed, δ 2 H and δ 34 S values of different defatted muscle, cattle tail hair, blood, liver, also δ 2h and δ 18 O values of water from muscle were determined by isotope ratio mass spectrometry. The stable sulfur isotope composition was not affected by cattle variety, meanwhile the hydrogen was uncertain; the δ 2 H and δ 34 S values between different defatted muscle, blood, liver, cattle hair were significantly different, at the same time the δ 34 S and δ 2 H values between each tissue were not significantly correlated; the δ 2 H values were strongly correlated with the δ 18 O values of muscle water. The above results indicated that stable sulfur and hydrogen isotopes fractionation in the various tissues were discrepant, thus the proper tissue should be selected according to the purpose and object in the beef traceability. (authors)

  13. Constraining late stage melt-peridotite interaction in the lithospheric mantle of southern Ethiopia: evidence from lithium elemental and isotopic compositions

    Science.gov (United States)

    Alemayehu, Melesse; Zhang, Hong-Fu; Seitz, Hans-Michael

    2017-10-01

    Lithium (Li) elemental and isotopic compositions for mineral separates of coexisting olivine, orthopyroxene and clinopyroxene of mantle xenoliths from the Quaternary volcanic rocks of southern Ethiopian rift (Dillo and Megado) reveal the influence of late stage melt-peridotite interaction on the early depleted and variably metasomatized lithospheric mantle. Two types of lherzolites are reported (LREE-depleted La/Sm(N) = 0.11-0.37 × Cl and LREE-enriched, La/Sm(N) = 1.88-15.72 × Cl). The depleted lherzolites have variable range in Li concentration (olivine: 2.1-5.4 ppm; opx: 1.1-2.3 ppm; cpx: 1.0-1.8 ppm) and in Li isotopic composition (δ7Li in olivine: -9.4 to 1.5‰; in opx: -4.5 to 3.6‰; in cpx: -17.0 to 4.8‰), indicating strong disequilibrium in Li partitioning and Li isotope fractionation between samples. The enriched lherzolites have limited range in both Li abundances (olivine: 2.7-3.0 ppm; opx: 1.1-3.1 ppm; cpx: 1.1-2.3 ppm) and Li isotopic compositions (δ7Li in olivine: -1.3 to +1.3‰; in opx: -2.0 to +5.0‰; in cpx: -7.5 to +4.8‰), suggest that the earlier metasomatic event which lead to LREE enrichment could also homogenize the Li contents and its isotopes. The enriched harzburgite and clinopyroxenite minerals show limited variation in Li abundances and variable Li isotopic compositions. The Li enrichments of olivine and clinopyroxene correlate neither with the incompatible trace element enrichment nor with the Sr-Nd isotopic compositions of clinopyroxene. These observations indicate that the metasomatic events which are responsible for the LREE enrichment and for the Li addition are distinct, whereby the LREE-enrichment pre-dates the influx of Li. The presence of large Li isotopic disequilibria within and between minerals of depleted and enriched peridotites suggest that the lithospheric mantle beneath the southern Ethiopian rift has experienced recent melt-peridotite interaction. Thus, the Li data set reported in this study offer new

  14. Tracing of ca 800 yr old mining activity in peat bog using Pb elemental concentrations and isotope compositions.

    Science.gov (United States)

    Baron, S.; Carignan, J.; Ploquin, A.

    2003-04-01

    Sixty sites of slags have been documented on the Mont-Lozère in southern France. The petrographic analysis shows that slags are metallurgical wastes (800 to 850 yr BP) which certainly result from smelting activity for lead and silver extraction (Ploquin et al., 2001). The aims of this study are: 1) to trace the source of Pb ores which supplied the smelting sites, by using the Pb isotopic composition of several surrounding Pb deposits, 2) to evaluate the actual pollution caused by these slags, by using elemental and isotopic compositions of soils, water and vegetation, and 3) to document the pollution history of the region, by using elemental and isotopic compositions of peat bog cores collected in the neighbourhood of the historical smelting sites. The lead isotopic composition of galena collected in most surrounding ores is very similar to that of different slag samples. On the other hand, the high precision of the results allowed us to select the mineralised areas which were probably the ore sources. The Pb isotopic composition of slags is even more homogeneous: 208/206 Pb: 2.092±0.002; 206/207 Pb: 1.179±0.001; 208/204 Pb: 38.663±0.025; 207/204 Pb: 15.665±0.006; 206/204 Pb: 18.476±0.023, and will allow source tracing in the environment. The "Narses Mortes" peat bog, around which two smelting sites have been reported, is strongly minerotrophic and contains 8 to 60% ash. A 1.40 m core have been retrieved and divided into 58 individual samples. Minerotrophic peat bog records both atmospheric deposition, soils leaching and the grounwater influence. The measured metal concentrations are normalised to Al contents of peat bog samples and the metal/Al ratios are compared to that of the Mont-Lozère granite: relative excess in metal concentrations are found in peat bog samples. An increasing excess of most metals (Pb, Zn, Cd...) was measured for surface samples, from 55 cm depth to the top of the core (23 cm depth). This profil might be attributed to atmospheric

  15. A rapid method for determination of the isotopic composition of uranium samples by alpha spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Martin Sanchez, A.; Tome, F.V.; Diaz Bejarano, J.; Jurado Vargas, M. (Dept. de Fisica, Univ. Extremadura, Badajoz (Spain))

    1992-03-01

    A simple method of analyzing alpha spectra from natural and enriched or depleted uranium samples is developed. The procedure is non-iterative, and takes into consideration low-energy tail and branching-ratio corrections to accurately calculate the area corresponding to each uranium isotope ({sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U) in the spectrum, and then the isotopic composition of the sample. A BASIC computer program, called ENURA, has been developed to perform all the necessary calculations to give the results together with their uncertainties. Several samples were prepared with different uranium concentrations made from standard solutions with known compositions, and the method was checked against the experimental measurements from these samples. Other series of uranium spectra were theoretically constructed using a given line shape in order to cover the required range of enriched or depleted uranium. (orig.).

  16. A rapid method for determination of the isotopic composition of uranium samples by alpha spectrometry

    Science.gov (United States)

    Sánchez, A. Martín; Tomé, F. Vera; Bejarano, J. Díaz; Vargas, M. Jurado

    1992-03-01

    A simple method of analyzing alpha spectra from natural and enriched or depleted uranium samples is developed. The procedure is non-iterative, and takes into consideration low-energy tail and branching-ratio corrections to accurately calculate the area corresponding to each uranium isotope (234U, 235U, 236U, 238U) in the spectrum, and then the isotopic composition of the sample. A BASIC computer program, called ENURA, has been developed to perform all the necessary calculations to give the results together with their uncertainties. Several samples were prepared with different uranium concentrations made from standard solutions with known compositions, and the method was checked against the experimental measurements from these samples. Other series of uranium spectra were theoretically constructed using a given line shape in order to cover the required range of enriched or depleted uranium.

  17. The effects of growth phase and salinity on the hydrogen isotopic composition of alkenones produced by coastal haptophyte algae

    NARCIS (Netherlands)

    Chivall, D.; M'Boule, D.; Sinke-Schoen, D.; Sinninghe Damsté, J.S.; Schouten, S.; van der Meer, M.T.J.

    2014-01-01

    The isotopic fractionation of hydrogen during the biosynthesis of alkenones produced by marine haptophyte algae has been shown to depend on salinity and, as such, the hydrogen isotopic composition of alkenones is emerging as a palaeosalinity proxy. The relationship between fractionation and salinity

  18. In-Situ Oxygen Isotopic Composition of Individual Minerals in Tagish Lake, a Unique Type 2 Carbonaceous Meteorite

    Science.gov (United States)

    Engrand, C.; Gounelle, M.; Duprat, J.; Zolensky, M. E.

    2001-01-01

    We measured the oxygen isotopic composition of individual minerals in Tagish Lake. The relationship with carbonaceous chondrites is confirmed. We found very O-16 enriched olivines. The carbonates will require a dedicated study of their C and O isotopes. Additional information is contained in the original extended abstract.

  19. In-Situ Oxygen Isotopic Composition of Tagish Lake: An Ungrouped Type 2 Carbonaceous Chondrite

    Science.gov (United States)

    Zolensky, Michael E.; Engrand, Cecile; Gounelle, Matthieu; Zolensky, Mike E.

    2001-01-01

    We have measured the oxygen isotopic composition of several components of Tagish Lake by ion microprobe. This meteorite constitutes the best preserved sample of C2 matter presently available for study. It presents two different lithologies (carbonate-poor and -rich) which have fairly comparable oxygen isotopic composition, with regard to both the primary or secondary minerals. For the olivine and pyroxene grains, their delta O-18 values range from - 10.5% to + 7.4% in the carbonate-poor lithology, with a mean Delta O-17 value of - 3.7 2.4%. In the carbonate-rich lithology, delta O-18 varies from - 7.9% to + 3.3%, and the mean Delta O-17 value is - 4.7 +/- 1.4%. Olivine inclusions (Fo(sub >99)) with extreme O-16-enrichment were found in both lithologies: delta O-18 = - 46.1 %, delta O-187= - 48.3% and delta O-18 = - 40.6%, delta O-17 = - 41.2% in the carbonate-rich lithology; delta O-18 = - 41.5%, delta O-17 = -43.4%0 in the carbonate-poor lithology. Anhydrous minerals in the carbonate-poor lithology are slightly more O-16-rich than in the carbonate-rich one. Four low-iron manganese-rich (LIME) olivine grains do not have an oxygen isotopic composition distinct from the other "normal" olivines. The phyllosilicate matrix presents the same range of oxygen isotopic compositions in both lithologies: delta O-18 from approximately 11 % to approximately 6%, with an average Delta. O-17 approximately 0%. Because the bulk Tagish Lake oxygen isotopic composition given by Brown et al. is on the high end of our matrix analyses, we assume that this "bulk Tagish Lake" composition probably only represents that of the carbonate-rich lithology. Calcium carbonates have delta O-18 values up to 35%, with Delta O-17 approximately 0.5%0. Magnetite grains present very high Delta O-17 values approximately + 3.4%0 +/- 1.2%. Given our analytical uncertainties and our limited carbonate data, the matrix and the carbonate seem to have formed in isotopic equilibrium. In that case, their large

  20. Mineralogy and Oxygen Isotope Compositions of an Unusual Hibonite-Perovskite Refractory Inclusion from Allende

    Science.gov (United States)

    Keller, L. P.; Snead, C.; Rahman, Z.; McKeegan, K. D.

    2012-01-01

    Hibonite-rich Ca- and Al-rich inclusions (CAIs) are among the earliest formed solids that condensed in the early nebula. We discovered an unusual refractory inclusion from the Allende CV3 chondrite (SHAL) containing an approx 500 micron long single crystal of hibonite and co-existing coarse-grained perovskite. The mineralogy and petrography of SHAL show strong similarities to some FUN inclusions, especially HAL. Here we report on the mineralogy, petrography, mineral chemistry and oxygen isotopic compositions in SHAL.

  1. GEOTRACES inter-calibration of the stable silicon isotope composition of dissolved silicic acid in seawater

    OpenAIRE

    Grasse, Patricia; Brzezinski, Mark A.; Cardinal, Damien; De Souza, Gregory F.; Andersson, Per; Closset, Ivia; Cao, Zhimian; Dai, Minhan; Ehlert, Claudia; Estrade, Nicolas; Francois, Roger; Frank, Martin; Jiang, Guibin; Jones, Janice L.; Kooijman, Ellen

    2017-01-01

    The first inter-calibration study of the stable silicon isotope composition of dissolved silicic acid in seawater, delta Si-30(OH)(4), is presented as a contribution to the international GEOTRACES program. Eleven laboratories from seven countries analyzed two seawater samples from the North Pacific subtropical gyre (Station ALOHA) collected at 300 m and at 1000 m water depth. Sampling depths were chosen to obtain samples with a relatively low (9 mmol L-1, 300 m) and a relatively high (113 mmo...

  2. In situ observations of the isotopic composition of methane at the Cabauw tall tower site

    Directory of Open Access Journals (Sweden)

    T. Röckmann

    2016-08-01

    Full Text Available High-precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS and a quantum cascade laser absorption spectroscopy (QCLAS-based technique for in situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw Experimental Site for Atmospheric Research (CESAR in the Netherlands and performed in situ, high-frequency (approx. hourly measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of (+0.25 ± 0.04 ‰ for δ13C and (−4.3 ± 0.4 ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high-precision and high-temporal-resolution dataset not only reveals the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget when they are performed at multiple sites that are representative for

  3. Investigating the source, transport, and isotope composition of water vapor in the planetary boundary layer

    Science.gov (United States)

    Griffis, Timothy J.; Wood, Jeffrey D.; Baker, John M.; Lee, Xuhui; Xiao, Ke; Chen, Zichong; Welp, Lisa R.; Schultz, Natalie M.; Gorski, Galen; Chen, Ming; Nieber, John

    2016-04-01

    Increasing atmospheric humidity and convective precipitation over land provide evidence of intensification of the hydrologic cycle - an expected response to surface warming. The extent to which terrestrial ecosystems modulate these hydrologic factors is important to understand feedbacks in the climate system. We measured the oxygen and hydrogen isotope composition of water vapor at a very tall tower (185 m) in the upper Midwest, United States, to diagnose the sources, transport, and fractionation of water vapor in the planetary boundary layer (PBL) over a 3-year period (2010 to 2012). These measurements represent the first set of annual water vapor isotope observations for this region. Several simple isotope models and cross-wavelet analyses were used to assess the importance of the Rayleigh distillation process, evaporation, and PBL entrainment processes on the isotope composition of water vapor. The vapor isotope composition at this tall tower site showed a large seasonal amplitude (mean monthly δ18Ov ranged from -40.2 to -15.9 ‰ and δ2Hv ranged from -278.7 to -113.0 ‰) and followed the familiar Rayleigh distillation relation with water vapor mixing ratio when considering the entire hourly data set. However, this relation was strongly modulated by evaporation and PBL entrainment processes at timescales ranging from hours to several days. The wavelet coherence spectra indicate that the oxygen isotope ratio and the deuterium excess (dv) of water vapor are sensitive to synoptic and PBL processes. According to the phase of the coherence analyses, we show that evaporation often leads changes in dv, confirming that it is a potential tracer of regional evaporation. Isotope mixing models indicate that on average about 31 % of the growing season PBL water vapor is derived from regional evaporation. However, isoforcing calculations and mixing model analyses for high PBL water vapor mixing ratio events ( > 25 mmol mol-1) indicate that regional evaporation can account

  4. Investigating the source, transport, and isotope composition of water vapor in the planetary boundary layer

    Directory of Open Access Journals (Sweden)

    T. J. Griffis

    2016-04-01

    Full Text Available Increasing atmospheric humidity and convective precipitation over land provide evidence of intensification of the hydrologic cycle – an expected response to surface warming. The extent to which terrestrial ecosystems modulate these hydrologic factors is important to understand feedbacks in the climate system. We measured the oxygen and hydrogen isotope composition of water vapor at a very tall tower (185 m in the upper Midwest, United States, to diagnose the sources, transport, and fractionation of water vapor in the planetary boundary layer (PBL over a 3-year period (2010 to 2012. These measurements represent the first set of annual water vapor isotope observations for this region. Several simple isotope models and cross-wavelet analyses were used to assess the importance of the Rayleigh distillation process, evaporation, and PBL entrainment processes on the isotope composition of water vapor. The vapor isotope composition at this tall tower site showed a large seasonal amplitude (mean monthly δ18Ov ranged from −40.2 to −15.9 ‰ and δ2Hv ranged from −278.7 to −113.0 ‰ and followed the familiar Rayleigh distillation relation with water vapor mixing ratio when considering the entire hourly data set. However, this relation was strongly modulated by evaporation and PBL entrainment processes at timescales ranging from hours to several days. The wavelet coherence spectra indicate that the oxygen isotope ratio and the deuterium excess (dv of water vapor are sensitive to synoptic and PBL processes. According to the phase of the coherence analyses, we show that evaporation often leads changes in dv, confirming that it is a potential tracer of regional evaporation. Isotope mixing models indicate that on average about 31 % of the growing season PBL water vapor is derived from regional evaporation. However, isoforcing calculations and mixing model analyses for high PBL water vapor mixing ratio events ( >  25 mmol mol−1

  5. In-situ observations of the isotopic composition of methane at the Cabauw tall tower site

    Science.gov (United States)

    Röckmann, Thomas; Eyer, Simon; van der Veen, Carina; E Popa, Maria; Tuzson, Béla; Monteil, Guillaume; Houweling, Sander; Harris, Eliza; Brunner, Dominik; Fischer, Hubertus; Zazzeri, Giulia; Lowry, David; Nisbet, Euan G.; Brand, Willi A.; Necki, Jaroslav M.; Emmenegger, Lukas; Mohn, Joachim

    2017-04-01

    High precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS) based technique for in-situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw experimental site for atmospheric research (CESAR) in the Netherlands and performed in-situ, high-frequency (approx. hourly) measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of +0.05 ± 0.03 ‰ for δ13C-CH4 and -3.6 ± 0.4 ‰ for δD-CH4. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high precision and temporal resolution dataset does not only reveal the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site, but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget, when they are performed at multiple sites that are representative for the entire European

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

    Science.gov (United States)

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

    1989-01-01

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

  7. Distinguishing ectomycorrhizal and saprophytic fungi using carbon and nitrogen isotopic compositions

    Directory of Open Access Journals (Sweden)

    Weiguo Hou

    2012-05-01

    Full Text Available Ectomycorrhizal fungi, a group of widespread symbiotic fungi with plant, obtain carbon source from trees and improve plant mineral nutrient uptake with their widespread hyphal network. Ectomycorrhizal fungi can be used as inoculants to improve the survival rates of plantation. Saprophytic fungi use the nutrition from the debris of plant or animals, and it is difficult to distinguish the saprophytic and ectomycorrhizal fungi by morphological and anatomic methods. In this research, the differences of stable carbon and nitrogen isotopic compositions of these fungi were analyzed. The results showed that the abundances of 13C of were higher than those of ectomycorrhizal fungi and the abundances of 15N of saprophytic fungi were lower than those of ectomycorrhizal fungi. Such differences of stable carbon and nitrogen isotopic compositions between ectomycorrhizal fungi and saprophytic fungi can be ascribed to their different nutrition sources and ecological functions. These results collectively indicate that stable carbon and nitrogen isotopic compositions are an effective proxy for distinguishing between ectomycorrhizal and saprophytic fungi.

  8. Changes in Isotopic Composition of Bottled Waters due to different Storage Conditions

    International Nuclear Information System (INIS)

    Ferjan, T.; Brencic, M.; Vreca, P.

    2011-01-01

    The aim of the study is to determine possible changes in isotopic composition of natural mineral waters stored in PET bottles in different environmental conditions from filling to consumption and to find out the rate to which described changes mask the primary natural mineral water characteristics. Packages of low mineralized natural mineral water of one particular brand were collected at the filling plant immediately after the end of production process to obtain representative state and chemical composition of water. Three storage sites with different physical conditions were appointed for bottled water storage. Comparative brands of low mineralised bottled water with different sources were located at one of the storage locations. During the first two months of the two years sampling period, sampling was carried out every 14 days and later on every two months. Water characteristics (pH, temperature, electroconductivity) were measured for each taken sample. Hydrogen and oxygen isotope analyses of the water samples were performed at the Joanneum Research Institute of Water Resources Management in Graz, Austria, while isotopic composition of dissolved inorganic carbon (δ 13 C DIC ) was determined at the Jozef Stefan Institute in Ljubljana.

  9. The Lu-Hf isotope composition of cratonic lithosphere: disequilibrium between garnet and clinopyroxene in kimberlite xenoliths

    NARCIS (Netherlands)

    Simon, N.S.C.; Carlson, R.W.; Pearson, D.G.; Davies, G.R.

    2002-01-01

    12th Annual V.M. Goldschmidt Conference Davos Switzerland, The Lu-Hf isotope composition of cratonic lithosphere: disequilibrium between garnet and clinopyroxene in kimberlite xenoliths (DTM, Carnegie Institution of Washington), Pearson, D.G. (University of Durham)

  10. Limitations of the isotopic composition of nitrates as a tracer of their origin

    Science.gov (United States)

    Kloppmann, Wolfram; Mayer, Bernhard; Otero, Neus; Sebilo, Mathieu; Gooddy, Daren; Lapworth, Dan; Surridge, Ben; Petelet Giraud, Emmanuelle; Flehoc, Christine; Baran, Nicole

    2017-04-01

    Nitrogen and oxygen isotopes are traditionally considered and frequently used as tracers of nitrate sources in watersheds used for drinking water production. The enrichment of synthetic nitrate-containing fertilizers in 18O due to the contribution of atmospheric oxygen in the production process confers a specific isotopic fingerprint to mineral fertilizers. In spite of the still widespread use on nitrate-containing synthetic fertilizers, their characteristic N and O isotope signatures are rarely unambiguously observed in nitrate-contaminated groundwater. We postulate, in line with Mengis et al. (2001), that fertilizer-derived nitrate is not directly and rapidly transferred to groundwater but rather retained in the soil-plant system as organic N and then mineralized and re-oxidized (termed the mineralization-immobilization turnover, MIT) thereby re-setting the oxygen isotope composition of nitrate and also changing its N isotope ratios. We show examples from watersheds on diverse alluvial/clastic and carbonate aquifers in eastern and northern France where, in spite of the use of mineral fertilizers, evidenced also through other isotopic tracers (boron isotopes), both N and O-isotope ratios are very homogeneous and compatible with nitrification of ammonium where 2/3 of oxygen is derived from soil water and 1/3 from atmospheric O2. These field data are corroborated by lysimeter data from Canada. Even if in areas where ammonium is derived from chemical fertilizers, N values still tend to be lower than in areas where ammonium is derived from manure/sewage, this is clearly a limitation to the dual isotope method (N, O) for nitrate source identification, but has important implications for the nitrogen mobility and residence time in soils amended with synthetic fertilizers (Sebilo et al., 2013). Mengis M., Walther U., Bernasconi S. M., Wehrli B. (2001) Limitations of Using δ18O for the Source Identification of Nitrate in Agricultural Soils. Environmental Science

  11. Tracking nitrous oxide emission processes at a suburban site with semicontinuous, in situ measurements of isotopic composition

    Science.gov (United States)

    Harris, Eliza; Henne, Stephan; Hüglin, Christoph; Zellweger, Christoph; Tuzson, Béla; Ibraim, Erkan; Emmenegger, Lukas; Mohn, Joachim

    2017-02-01

    The isotopic composition of atmospheric nitrous oxide (N2O) was measured semicontinuously, at ˜35 min frequency in intermittent periods of 1-6 days over one and a half years, using preconcentration coupled to a quantum cascade laser spectrometer at the suburban site of Dübendorf, Switzerland. The achieved measurement repeatability was 0.08‰, 0.11‰, and 0.10‰ for δ18O, site preference, and δ15Nbulk respectively, which is better than or equal to standard flask sampling-based isotope ratio mass spectrometry performance. The observed mean diurnal cycle reflected the buildup of N2O from isotopically light sources on an isotopically heavy tropospheric background. The measurements were used to determine the source isotopic composition, which varied significantly compared to chemical and meteorological parameters monitored at the site. FLEXPART-COSMO transport modeling in combination with modified Emissions Database for Global Atmospheric Research inventory emissions was used to model N2O mole fractions at the site. Additionally, isotopic signatures were estimated for different source categories using literature data and used to simulate N2O isotopic composition over the measurement period. The model was able to capture variability in N2O mole fraction well, but simulations of isotopic composition showed little agreement with observations. In particular, measured source isotopic composition exhibited one magnitude larger variability than simulated, clearly indicating that the range of isotopic source signatures estimated from literature significantly underestimates true variability of source signatures. Source δ18O signature was found to be the most sensitive tracer for urban/industry versus agricultural N2O. δ15Nbulk and site preference may provide more insight into microbial and chemical emission processes than partitioning of anthropogenic source categories.

  12. Correlation Between Stable Isotope Composition and Cloud Altitude (Radar Echo Tops) in Tropical Rainfall: Puerto Rico and Hawaii

    Science.gov (United States)

    Scholl, M. A.; Coplen, T. B.

    2010-12-01

    Observed patterns of isotopic composition of rainfall in the tropics are different than those at higher latitudes, where seasonal temperature changes have a large effect. Land surface temperatures vary little over the course of the year in the tropics, and the amount effect (involving evaporative enrichment, droplet size, and rainout processes) has been invoked as an explanation for variations in isotopic composition of rain measured at the land surface. Previous work by Scholl et al. (2009) in Eastern Puerto Rico showed that variations in the altitude (and temperature) of the clouds producing rain were highly correlated with the monthly stable isotope composition of rainfall. The altitude of rain droplets within the clouds was obtained using NEXRAD echo tops, which indicate the maximum altitude of rainfall determined by radar. Atmospheric temperature in rainfall-producing clouds was then estimated with archived NCEP data at the mean and maximum echo top altitudes for large rain events during the sampling period. Isotopic signatures associated with the major climate patterns in Puerto Rico were determined and are being utilized in local hydrological studies. For Eastern Puerto Rico, at latitude 18° N, δ18O and δ2H values and mean monthly echo top altitude were significantly correlated (average coefficient = -0.69). The analysis was repeated using a 24-month stable isotope data set of rain from sites on windward and leeward Maui, Hawaii, latitude 21° N. Results were similar; mean monthly echo top altitude was highly correlated with rainfall isotopic composition (windward site correlation coefficient = -0.86, leeward = -0.87). The data also showed a significant rainout effect in monthly samples dominated by tropical storms, where cloud heights were similar to other monthly samples but δ18O and δ2H values were much more negative. Variations in water vapor isotopic composition also affect isotopic composition of rain, and ongoing work will focus on investigating

  13. Seasonal Variation in the Distribution and Isotopic Composition of Phytoplankton in an Amazon Floodplain Lake, Brazil

    Directory of Open Access Journals (Sweden)

    Pedro Caraballo Gracia

    2014-05-01

    Full Text Available To evaluate the seasonal variation and isotopic composition of phytoplankton, water samples were collected monthly between October 2007 and November 2008 in Lake Catalão, a floodplain lake at the confluence between rivers Negro and Amazon. Analyses of total chlorophyll concentration and δ13C and δ15N isotopic abundances were made from particulate size fractions of 30-60, 10-30 and <10 µm in the littoral, pelagic, and floating meadows regions. Chlorophyll concentration was found to be inversely associated to lake depth, and high concentrations of chlorophyll in the floating meadows zone were significant.  The fraction <10 µm was the most abundant representing in average more than 40% of the particulate matter. The δ13C values were relatively constant during the study (-25.1‰ ~ -34.0‰, whereas the δ15N values showed strong variability (15.6‰ ~ 2.4‰, which has been attributed to the resuspension of sediments during mixing of the water column. Mixing associated to the sudden drop in temperature during the rising water period was an important event in the trophic and isotopic dynamics of the lake. Variations in chlorophyll content were generally associated with the dilution process, in which concentration was inversely correlated to the water level, whereas abundance was directly correlated to the water level. VARIACIÓN ESTACIONAL DE LA DISTRIBUCIÓN Y COMPOSICIÓN ISOTÓPICA DEL FITOPLANCTON EN UN LAGO DE INUNDACIÓN EN LA AMAZONIA, BRASIL.   Con el propósito de evaluar la variación estacional de la abundancia isotópica (δ13C e δ15N del fitoplancton, muestreos mensuales fueron realizados entre octubre de 2007 y noviembre de 2008 en el lago Catalão, un lago de inundación en la zona de confluencia de los ríos Negro y Solimões, ubicado frente a la ciudad de Manaus (AM, Brasil. Análisis de la clorofila total y evaluaciones de la abundancia natural de δ13C y δ15N fueron realizados en las fracciones partículadas de 30-60, 10

  14. The bulk isotopic composition of hydrocarbons in subaerial volcanic-hydrothermal emissions from different tectonic settings

    Science.gov (United States)

    Fiebig, J.; Tassi, F.; Vaselli, O.; Viveiros, M. F.; Silva, C.; Lopez, T. M.; D'Alessandro, W.; Stefansson, A.

    2015-12-01

    Assuming that methane and its higher chain homologues derive from a common source, carbon isotope patterns have been applied as a criterion to identify occurrences of abiogenic hydrocarbons. Based on these, it has been postulated that abiogenic hydrocarbon production occurs within several (ultra)mafic environments. More evolved volcanic-hydrothermal systems may also provide all the prerequisites necessary for abiogenic hydrocarbon production, such as availability of inorganic CO2, hydrogen and heat. We have investigated the chemical and isotopic composition of n-alkanes contained within subaerial hydrothermal discharges emitted from a range of hot spot, subduction and rift-related volcanoes to determine the origin of hydrocarbons in these systems. Amongst these are Nisyros (Greece), Vesuvio, Campi Flegrei, Ischia, Pantelleria and Vulcano (all Italy), Mt. Mageik and Trident (USA), Copahue (Argentina), Teide (Spain), Furnas and Fogo (Portugal). The carbon isotopic composition of methane emitted from these sites varies from -65 to -8‰ , whereas δ13C of ethane and propane exhibit a much narrower variation from -17‰ to -31‰. Methane that occurs most enriched in 13C is also characterized by relatively positive δD values ranging up to -80‰. Carbon isotope reversals between methane and ethane are only observed for locations exhibiting δ13C-CH4 values > -20‰, such as Teide, Pantelleria, Trident and Furnas. At Furnas, δ13C-CH4 varies by 50‰ within a relatively short distance of <50m between two vents, whereas δ13C-C2H6 varies by less than 2‰ only. For some of the investigated locations apparent carbon isotopic temperatures between methane and CO2 are in agreement with those derived from gas concentration geothermometers. At these locations methane, however seems to be in disequilibrium with ethane and propane. These findings imply that methane on the one hand and the C2+ hydrocarbons on the other hand often might derive from distinct sources.

  15. Carbon-13 isotopic composition of distillation fractions of some Egyptian crude oils

    International Nuclear Information System (INIS)

    Aly, A.I.M.; Hamza, M.S.; Abd Elsamie, S.G.

    1991-01-01

    13 C/ 13 C ratios were determined for some crude oil fields in the Gulf of Suez and Western Desert provinces. The crude oil was subjected to distillation at atmospheric pressure and subsequently under vacuum. Distillation fractions were collected at 25 degree C intervals. Carbon-13 content of these distillation fractions showed some differences in the degree of isotopic fractionation. The results were interpreted in view of the age of the source rocks and the degree of maturation process. The carbon-13 content of distillation fractions may be helpful in revealing petroleum mechanisms which can be exploited in exploration.4 fig

  16. Seasonal and ENSO Influences on the Stable Isotopic Composition of Galápagos Precipitation

    Science.gov (United States)

    Martin, N. J.; Conroy, J. L.; Noone, D.; Cobb, K. M.; Konecky, B. L.; Rea, S.

    2018-01-01

    The origin of stable isotopic variability in precipitation over time and space is critical to the interpretation of stable isotope-based paleoclimate proxies. In the eastern equatorial Pacific, modern stable isotope measurements in precipitation (δ18Op and δDp) are sparse and largely unevaluated in the literature, although insights from such analyses would benefit the interpretations of several regional isotope-based paleoclimate records. Here we present a new 3.5 year record of daily-resolved δ18Op and δDp from Santa Cruz, Galápagos. With a prior 13 year record of monthly δ18Op and δDp from the island, these new data reveal controls on the stable isotopic composition of regional precipitation on event to interannual time scales. Overall, we find Galápagos δ18Op is significantly correlated with precipitation amount on daily and monthly time scales. The majority of Galápagos rain events are drizzle, or garúa, derived from local marine boundary layer vapor, with corresponding high δ18Op values due to the local source and increased evaporation and equilibration of smaller drops with boundary layer vapor. On monthly time scales, only precipitation in very strong, warm season El Niño months has substantially lower δ18Op values, as the sea surface temperature threshold for deep convection (28°C) is only surpassed at these times. The 2015/2016 El Niño event did not produce strong precipitation or δ18Op anomalies due to the short period of warm SST anomalies, which did not extend into the peak of the warm season. Eastern Pacific proxy isotope records may be biased toward periods of high rainfall during strong to very strong El Niño events.

  17. Isotopic composition on ground ice in Western Yamal (Marre-Sale

    Directory of Open Access Journals (Sweden)

    I. D. Streletskaya

    2013-01-01

    Full Text Available The profile of Quaternary sediments near Marre-Salle polar station, Western Yamal Peninsula, has large bodies of tabular ground ice. This profile is considered strata-typical and critical in understanding of paleogeographic conditions of the Arctic in Pleistocene-Holocene. However, interpretation of the profile is under discussion. It consists of two distinct strata: upper layer of 10–15 m thick represented by continental sediments and lower one with a thickness of more than 100 m represented by marine sediments. Lower layer of saline marine clays has lenses of tabular ground ice (more than 20 m thick, the bases of which are below the sea level. Upper continental layer is characterized by syngenetic ice-wedges of different generations. Samples were collected from ice-wedges and tabular ground ice for chemical and isotope analysis. The results of the analysis allow to reconstruct paleogeographic conditions of the sedimentation and freezing of Quaternary sediments. Heavy stable isotope content and relationship between oxygen and hydrogen isotopes show that the ice bodies in the lower layer were formed in-situ within the ground. In the upper layer, heavier isotope content found in younger ice-wedges relative to the old-generation wedges. Formation of massive syngenetic Upper-Pleistocene ice-wedges occurred in conditions of colder winter temperatures than at present. Syngenetic Holocene wedges were formed after Holocene Optimum under winter conditions similar to present. Younger ice wedges formed smaller polygons, were smaller and often were developing in the locations of the degraded old wedges. Results of the isotope analysis of various types of ground ice near Marre-Sale allow reconstructing changes of marine sedimentation to continental one around Kargino time (MIS 3 and changes in climatic conditions in Arctic in Late Pleistocene and Holocene.

  18. Isotopic Composition and Organic Geochemistry of Nitrogen at the Cretaceous/Tertiary Boundary

    Science.gov (United States)

    Gardner, A.; Hildebrand, A.; Gilmour, I.

    1992-07-01

    The boundary clays from several marine K/T sites are known to be enriched in nitrogen and to show marked shifts in nitrogen isotopic compositions (1, 2, 3). At Woodside Creek, New Zealand, a 20-fold increase in nitrogen concentration has been observed together with a corresponding shift in delta^15N of +10o/oo, (1, 2). Similarly at Caravaca and Bidart, Spain, ^15N enrichments of between +12 and +18%o have been found (3) although the same study found no ^15N enrichments at Gubbio, Italy, or Stevns Klint, Denmark. The source of this excess nitrogen, which can result in N/C ratios up to 0.1 is still unknown (typical N/C values for sediments are around 0.01). It has been suggested that it may be a signature of nitric acid rain or reflect a rapid onset of anoxic conditions in the world's oceans. In order to try and distinguish between these possibilities we have measured the abundance and isotopic composition of nitrogen and examined the molecular organic geochemistry of samples from a nonmarine site in the Northwest Territory of Canada, Police Island . A total of 10 samples from across the K/T boundary at Police Island were solvent-extracted using MeOH/CH2Cl2; a kerogen/elemental carbon fraction was isolated by HF/HCl digestion of silicates. Analysis of the nitrogen content and isotopic composition of the kerogen reveals an enrichment in nitrogen in the fireball layer and a corresponding shift in delta^15N. Nitrogen concentrations increase by ca. 8-fold to 11,600 ppm in the 0.3-cm-thick fireball layer over the underlying ejecta layer. The lowermost Tertiary samples show a progressive decrease to 6200 ppm then 1800 ppm over the next 2-3 cm. delta^15N values shift by +3% from 3.3% in the ejecta layer to +6.2% in the fireball layer. Both the abundance and isotopic variations are in the same direction as observed at marine sites, though of lesser magnitude. The total MeOH/CH2Cl2 extract was analyzed by gas chromatography/mass spectrometry. The boundary and lowermost

  19. Isotopic Composition of the Neolithic Alpine Iceman's Tooth Enamel and Clues to his Origin

    Science.gov (United States)

    Muller, W.; Muller, W.; Halliday, A. N.

    2001-12-01

    Five small enamel fragments from three teeth of the upper right jaw from the mummy of the Neolithic Alpine Iceman have been investigated for their isotopic composition in order to shed light on his geographic origins. Soils from approximately contemporaneous sites were sampled for comparison. Tooth enamel forms ontogenetically very early and is not re-mineralized during later lifetime (unlike with bone material). Therefore, unique insights into the Iceman's childhood can be acquired. Enamel also is the densest tissue of a human body and is thus less susceptible to post-mortem alteration. Both radiogenic (Sr, Pb, Nd) and stable isotopes (O, C) are investigated. Radiogenic isotopes allow reconstruction of the local geological background, because humans incorporate Sr, Pb and Nd from their local environment by eating local food. Stable isotopes provide information about altitude and/or position relative to the main Alpine watershed. High spatial-resolution laser-ablation ICPMS profiles reveal that most elements are distributed in a manner that is essentially similar to modern human teeth except of that La, Ce, Nd (LREE) show up to a 100-fold enrichment towards the outer enamel surface. These uptake-profiles may reflect interaction with melt water, consistent with data for the composition of samples of the Iceman's skin. Biogenic apatites (enamel, bone) have very low in-vivo LREE concentrations, but take up LREEs post-mortem from the burial environment. Ice core samples from the finding site show concentrations up to 400 ppt Ce. Such high uptake of the LREEs precludes the derivation of an in-vivo Nd isotopic signal, but both other radiogenic tracers, Sr and Pb, show pristine (in-vivo) concentrations of 87 ppm and 0.1 ppm, respectively. Strontium isotopic compositions were determined on fragments from the canine, the first and second premolar (1 - 9 mg) and two hip bone samples, utilizing three sequential leaching steps for each sample to detect possible alteration

  20. New perspectives on the Li isotopic composition of the upper continental crust and its weathering signature

    Science.gov (United States)

    Sauzéat, Lucie; Rudnick, Roberta L.; Chauvel, Catherine; Garçon, Marion; Tang, Ming

    2015-10-01

    Lithium isotopes are increasingly used to trace both present-day and past weathering processes at the surface of the Earth, and could potentially be used to evaluate the average degree of past weathering recorded by the upper continental crust (UCC). Yet the previous estimate of average δ7Li of the UCC has a rather large uncertainty, hindering the use of Li isotopes for this purpose. New δ7Li for desert and periglacial loess deposits (windblown dust) from several parts of the world (Europe, Argentina, China and Tajikistan) demonstrate that the former are more homogeneous than the latter, and may therefore serve as excellent proxies of the average composition of large tracts of the UCC. The Li isotopic compositions and concentrations of desert loess samples are controlled by eolian sorting that can be quantified by a binary mixing between a weathered, fine-grained end-member, dominated by phyllosilicates and having low δ7Li, and an unweathered, coarse-grained end-member, that is a mixture of quartz and plagioclase having higher δ7Li. We use correlations between insoluble elements (REE, Nd/Hf and Fe2O3/SiO2), Li concentrations (henceforth referred as [Li]), and δ7Li to estimate a new, more precise, average Li isotopic composition and concentration for the UCC: [ Li ] = 30.5 ± 3.6 (2 σ) ppm, and δ7Li = + 0.6 ± 0.6 (2 σ). The δ7Li for desert loess deposits is anti-correlated with the chemical index of alteration (CIA). Using this relationship, along with our average δ7Li, we infer that (1) the present-day CIA of the average UCC is 61-2+4 (2 σ), higher than the common reference value of 53, and (2) the average proportion of chemically weathered components is as high as 37-10+17 (2 σ)% at the surface of the Earth.

  1. Assessing the ability of isotope-enabled General Circulation Models to simulate the variability of Iceland water vapor isotopic composition

    Science.gov (United States)

    Erla Sveinbjornsdottir, Arny; Steen-Larsen, Hans Christian; Jonsson, Thorsteinn; Ritter, Francois; Riser, Camilla; Messon-Delmotte, Valerie; Bonne, Jean Louis; Dahl-Jensen, Dorthe

    2014-05-01

    During the fall of 2010 we installed an autonomous water vapor spectroscopy laser (Los Gatos Research analyzer) in a lighthouse on the Southwest coast of Iceland (63.83°N, 21.47°W). Despite initial significant problems with volcanic ash, high wind, and attack of sea gulls, the system has been continuously operational since the end of 2011 with limited down time. The system automatically performs calibration every 2 hours, which results in high accuracy and precision allowing for analysis of the second order parameter, d-excess, in the water vapor. We find a strong linear relationship between d-excess and local relative humidity (RH) when normalized to SST. The observed slope of approximately -45 o/oo/% is similar to theoretical predictions by Merlivat and Jouzel [1979] for smooth surface, but the calculated intercept is significant lower than predicted. Despite this good linear agreement with theoretical calculations, mismatches arise between the simulated seasonal cycle of water vapour isotopic composition using LMDZiso GCM nudged to large-scale winds from atmospheric analyses, and our data. The GCM is not able to capture seasonal variations in local RH, nor seasonal variations in d-excess. Based on daily data, the performance of LMDZiso to resolve day-to-day variability is measured based on the strength of the correlation coefficient between observations and model outputs. This correlation coefficient reaches ~0.8 for surface absolute humidity, but decreases to ~0.6 for δD and ~0.45 d-excess. Moreover, the magnitude of day-to-day humidity variations is also underestimated by LMDZiso, which can explain the underestimated magnitude of isotopic depletion. Finally, the simulated and observed d-excess vs. RH has similar slopes. We conclude that the under-estimation of d-excess variability may partly arise from the poor performance of the humidity simulations.

  2. Determination of stable carbon isotope compositions in individual amino acids of anchovy engraulis japonicus by GC-C-IRMS

    International Nuclear Information System (INIS)

    Liu Haizhen; Cai Deling; Zhang Longjun

    2005-01-01

    The stable carbon isotope compositions of individual amino acids in muscle tissues of the anchovy, Engraulis japonicus, a key species of animal in the Yellow and the East China Sea ecosystem, were determined by the gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Eleven amino acid compounds were identified and their δ( 13 C) values were successfully measured. The new ability to measure stable carbon isotope compositions of individual amino acids offers a potential method for understanding digest, absorption and metabolism of anchovy, Engraulis japonicus, pathway of carbon transfer through food web and evaluating trophic quality of diet. (authors)

  3. Biomarkers, carbon isotopic composition and source rock potentials of Awgu coals, middle Benue trough, Nigeria

    Science.gov (United States)

    Adedosu, Taofik A.; Sonibare, Oluwadayo O.; Tuo, Jincai; Ekundayo, Olusegun

    2012-05-01

    Coal and carbonaceous shale samples were collected from two boreholes (BH 94 and BH 120) in Awgu formation of Middle Benue Trough, Nigeria. Source rock potentials of the samples were studied using biomarkers and carbon isotopic composition. Biomarkers in the aliphatic fractions in the samples were studied using Gas Chromatography-Mass Spectrometry (GC-MS). The Carbon isotope analysis of individual n-alkanes in the aliphatic fraction was performed using Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometer (GC-IRMS). The abundance of hopanes, homohopanes (C31-C35), and C29 steranes in the samples indicate terrestrial plant, phytoplankton and cyanobacteria contributions to the organic matter that formed the coal. High (Pr/Ph) ratio (3.04-11.07) and isotopic distribution of individual alkanes showed that the samples consisted of mixed terrestrial/marine organic matter deposited under oxic condition in lacustrine-fluvial/deltaic depositional environment. The maturity parameters derived from biomarker distributions showed that the samples are in the main phase of oil window.

  4. C, Sr and Sr isotopic composition on probable vendian- tommotian carbonate sequences in Nw Argentina

    International Nuclear Information System (INIS)

    Sial, A. N.; Ferreira, V.P; Toselli, A.J.; Acenolaza, F.G; Pimentel, M.M; Parada, M.A; Alonso, R.N

    2001-01-01

    C-isotope stratigraphy is one of the most powerfool tools in Precambrian chronostratigraphy, especially when sediments lack recognizable animal fossils. The δ 13 C secular variation curves for marine carbonates in the Neoproterozoic-Cambrian interval show strong positive-negative excursions, several of them interpreted as the stratigraphic position of ancient ice ages (Hoffman et al. 1998). The Sr isotope composition of the seawater for this age interval is characterized by a continuous increase of 87 Sr/ 86 Sr that is interrupted, several times, by sharp rises, which represent important changes in the Earth history (Montanez et al. 2000). Only limited data on the behavior of C and Sr isotopes in carbonates are available in South America. We examine here carbonate sequences from the Argentine Precordillera, San Juan province, and from other carbonate sequences in NW Argentina that could be, potentially, proxies for the Precambrian-Cambrian transition. We have studied their δ 13 C and 87 Sr/ 86 Sr chemostratigraphy and compare it to global C and Sr isotope secular variation curves for this time span. This study aims to improve the relatively coarse stratigraphic resolution provided only by the study of the fossil record in some of the carbonate successions under consideration (au)

  5. Stable isotope composition of land snail body water and its relation to environmental waters and shell carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Goodfriend, G.A.; Magaritz, M.; Gat, J.R. (Weizmann Institute of Science, Rehovot (Israel))

    1989-12-01

    Day-to-day and within-day (diel) variations in {delta}D and {delta}{sup 18}O of the body water of the land snail, Theba pisana, were studied at a site in the southern coastal plain of Israel. Three phases of variation, which relate to isotopic changes in atmospheric water vapor, were distinguished. The isotopic variations can be explained by isotopic equilibration with atmospheric water vapor and/or uptake of dew derived therefrom. During the winter, when the snails are active, there is only very minor enrichment in {sup 18}O relative to equilibrium with water vapor or dew, apparently as a result of metabolic activity. But this enrichment becomes pronounced after long periods of inactivity. Within-day variation in body water isotopic composition is minor on non-rain days. Shell carbonate is enriched in {sup 18}O by ca. 1-2% relative to equilibrium with body water. In most regions, the isotopic composition of atmospheric water vapor (or dew) is a direct function of that of rain. Because the isotopic composition of snail body water is related to that of atmospheric water vapor and the isotopic composition of shell carbonate in turn is related to that of body water, land snail shell carbonate {sup 18}O should provide a reliable indication of rainfall {sup 18}O. However, local environmental conditions and the ecological properties of the snail species must be taken into account.

  6. A New Passive Fog Collector Design for Measuring Fog Water Inputs and Isotopic Composition in Harsh and Remote Environments

    Science.gov (United States)

    Fischer, D. T.; Still, C. J.

    2005-12-01

    collectors have been analyzed monthly for stable isotope content as part of the larger study. Large differences in isotopic composition between fog and rain waters are used to partition ecosystem use of their hydrologic inputs. Additional collectors are being installed for companion studies on the California mainland coast (Cambria), and in tropical montane cloud forest sites (Monteverde, Costa Rica).

  7. The genesis and isotopic composition of carbonates associated with some Permian Australian coals

    International Nuclear Information System (INIS)

    Gould, K.W.; Smith, J.W.

    1979-01-01

    Siderite and calcite are the two forms of carbonate commonly associated with Permian Australian coals. The former occurs as disseminated spherulites and is a product of the early post-depositional environment. Isotopic measurements show that the CO 2 fixed as siderite did not result from the direct oxidation of photosynthetically derived materials, but rather from the anaerobic fermentation of these. The higher concentrations of calcite are generally found towards the roofs of coal seams and are characterized by isotopic enrichments to delta 13 C values of +25% PDB. Isotopic exchange between CO 2 and CH 4 within the coal seam is postulated as the mechanism which leads to the formation of isotopically heavy CO 2 . At sites along the seam margins where the CO 2 escapes, interaction with circulating metal ions or preexisting calcite results in the deposition of ''heavy'' calcite. With increasing alteration of coal by thermal metamorphism, the 13 C content of calcites and finally siderites decreases so that it more nearly approaches that of the associated coal. (Auth.)

  8. The feasibility of assessing the diets of minke whale ( Balaenoptera acutorostrata) in the East Sea through fatty acid composition in blubber and stable isotopic ratio of skin

    Science.gov (United States)

    Ko, Ah-Ra; Ju, Se-Jong; Choi, Seok-Gwan; Shin, Kyung-Hoon

    2016-09-01

    To track the diet of minke whale ( Balaenoptera acutorostrata) in the East Sea (Japan Sea), a conjoint analysis of fatty acids and C and N stable isotopes was performed on blubber and skin from the whale and its potential prey. The total lipid content in the blubber of minke whales ranged from 37.9% to 82.7% of wet mass (mean ± SD, 63.1 ± 17.2%), with triacylglycerols being the dominant lipids (96.9%-99.2% of total lipids). The lipid and fatty acid (FA) contents were systematically stratified throughout the depth of the blubber layers; contents of the dominant monounsaturated FAs (MUFAs), including 18:1ω9 and 16:1ω7, increased from the innermost layer to the outermost layer, whereas contents of saturated FAs (SFAs) and polyunsaturated FAs (PUFAs) were higher in the innermost layer than in the outermost layer. This stratification is related to the different physiological roles of the blubber layers; e.g., thermoregulation, streaming, and buoyancy. A comparison of the FA compositions of the innermost layer of minke whales with those of potential prey indicates that FA compositions in the whales are similar to those of Pacific herring. In addition, stable isotope ratios (δ13C and δ15N) suggest that minke whale and Pacific herring have the same or similar diets. Therefore, the diets of minke whale from the East Sea (Japan Sea) could be inferred from information on the diet of the Pacific herring, although FA compositions and stable isotope ratios for Pacific herring would not exactly reflect the whale's diet. Although the very limited number of samples was used in this study, our preliminary findings are very promising to help understand the feeding ecology of minke whales in the East Sea (Japan Sea).

  9. The isotope composition of inorganic germanium in seawater and deep sea sponges

    Science.gov (United States)

    Guillermic, Maxence; Lalonde, Stefan V.; Hendry, Katharine R.; Rouxel, Olivier J.

    2017-09-01

    Although dissolved concentrations of germanium (Ge) and silicon (Si) in modern seawater are tightly correlated, uncertainties still exist in the modern marine Ge cycle. Germanium stable isotope systematics in marine systems should provide additional constraints on marine Ge sources and sinks, however the low concentration of Ge in seawater presents an analytical challenge for isotopic measurement. Here, we present a new method of pre-concentration of inorganic Ge from seawater which was applied to measure three Ge isotope profiles in the Southern Ocean and deep seawater from the Atlantic and Pacific Oceans. Germanium isotopic measurements were performed on Ge amounts as low as 2.6 ng using a double-spike approach and a hydride generation system coupled to a MC-ICP-MS. Germanium was co-precipitated with iron hydroxide and then purified through anion-exchange chromatography. Results for the deep (i.e. >1000 m depth) Pacific Ocean off Hawaii (nearby Loihi Seamount) and the deep Atlantic off Bermuda (BATS station) showed nearly identical δ74/70Ge values at 3.19 ± 0.31‰ (2SD, n = 9) and 2.93 ± 0.10‰ (2SD, n = 2), respectively. Vertical distributions of Ge concentration and isotope composition in the deep Southern Ocean for water depth > 1300 m yielded an average δ74/70Ge = 3.13 ± 0.25‰ (2SD, n = 14) and Ge/Si = 0.80 ± 0.09 μmol/mol (2SD, n = 12). Significant variations in δ74/70Ge, from 2.62 to 3.71‰, were measured in the first 1000 m in one station of the Southern Ocean near Sars Seamount in the Drake Passage, with the heaviest values measured in surface waters. Isotope fractionation by diatoms during opal biomineralization may explain the enrichment in heavy isotopes for both Ge and Si in surface seawater. However, examination of both oceanographic parameters and δ74/70Ge values suggest also that water mass mixing and potential contribution of shelf-derived Ge also could contribute to the variations. Combining these results with new Ge isotope data

  10. [Composition and content of biologically active substances in rose hips].

    Science.gov (United States)

    Dubtsova, G N; Negmatulloeva, R N; Bessonov, V V; Baĭkov, V G; Sheviakova, L V; Makhova, N N; Perederiaev, O I; Bogachuk, M N; Baĭgarin, E K

    2012-01-01

    The paper studies the chemical composition of the powders obtained from the pulp with the skins and seeds of fruits of wild rose hips. Research results have shown that the main fraction of the powder is dietary fiber, powder of seeds of insoluble fiber in 1,6 and 2,3 higher than in the powder of the fruit with a thin skin and pulp, respectively. The greatest amount of carbohydrates and protein found in powders and pulp of the fruit with a thin skin, and lipids predominate in the powder from the seeds. Found that the lipid powder rosehip richest in oleic, linoleic and linolenic acids, the share of oleic acid has 6,4-19,2%, linoleic and linolenic 19,7-45,8 and 23,3-33,9% of the amount of fatty acids. Lipids powders of hips and seeds of rose have higher levels of essential linoleic acid and powder from the pulp with the skins - linolenic acid. In the study established the presence of sterols 7 fractions, the predominant of which is the beta-sitosterol. In the powder from the pulp with the skins found the greatest amount of ascorbic acid, carotenoids, and the powder of seeds - vitamin E. Carotenoids in powders are beta-carotene and lycopene. The high content of ascorbic acid, vitamin E and carotenoids in powder from wild rose hips makes them a good source of antioxidants. Therefore, we studied the possibility of using vegetable powders obtained from hips of wild rose, to enrich biologically active substances such as vitamins C, E and carotenoids, food supply, particularly of health care use. Rosehip powder from the pulp with the skins had the highest antioxidant activity, antioxidant activity of hips powders was 74% of the activity of powder from the pulp with the skins, the lowest antioxidant activity was observed in the powder from the wild rose seeds. That's way, based on the analysis of the chemical composition of rose hip powder found high levels they ascorbic acid, carotenoids, flavonoids,found their high antioxidant activity. It allows to recommend powders

  11. Changing compositions in the Iceland plume; Isotopic and elemental constraints from the Paleogene Faroe flood basalts

    DEFF Research Database (Denmark)

    Søager, Nina; Holm, Paul Martin

    2011-01-01

    Elemental and Sr, Nd, Hf and high precision Pb isotopic data are presented from 59 low-Ti and high-Ti lavas from the syn-break up part of the Faroe Flood Basalt Province. The depleted MORB-like low-Ti lavas erupted in the rift zone between the Faroe Islands and central East Greenland around...... the time of break up of the North Atlantic have isotopic end-member compositions different from the depleted Iceland lavas. We suggest that the main low-Ti mantle component is NAEM (North Atlantic End-Member (Ellam and Stuart, 2000, J. Petrol. 41, 919) and that the 207Pb/204Pb value of the component should...... be 15.35 and eHf=+16.5. NAEM is the main depleted component in the early Iceland plume. This is supported by high mantle potential temperatures (up to 1550 °C) calculated for the source of the low-Ti basalts. The unique mantle isotopic composition of NAEM with low 206Pb/204Pb (17.5) and ¿7/4Pb (-3...

  12. Analysis of burnup and isotopic compositions of BWR 9 x 9 UO2 fuel assemblies

    International Nuclear Information System (INIS)

    Suzuki, M.; Yamamoto, T.; Ando, Y.; Nakajima, T.

    2012-01-01

    In order to extend isotopic composition data focusing on fission product nuclides, measurements are progressing using facilities of JAEA for five samples taken from high burnup BWR 9 x 9 UO 2 fuel assemblies. Neutronics analysis with an infinite assembly model was applied to the preliminary measurement data using a continuous-energy Monte Carlo burnup calculation code MVP-BURN with nuclear libraries based on JENDL-3.3 and JENDL-4.0. The burnups of the samples were determined to be 28.0, 39.3, 56.6, 68.1, and 64.0 GWd/t by the Nd-148 method. They were compared with those calculated using node-average irradiation histories of power and in-channel void fractions which were taken from the plant data. The comparison results showed that the deviations of the calculated burnups from the measurements were -4 to 3%. It was confirmed that adopting the nuclear data library based on JENDL-4.0 reduced the deviations of the calculated isotopic compositions from the measurements for 238 Pu, 144 Nd, 145 Nd, 146 Nd, 148 Nd, 134 Cs, 154 Eu, 152 Sm, 154 Gd, and 157 Gd. On the other hand, the effect of the revision in the nuclear. data library on the neutronics analysis was not significant for major U and Pu isotopes. (authors)

  13. The stable isotopic composition of respired CO2 - measurements on ecosystem scale using IRIS

    Science.gov (United States)

    Braden-Behrens, J.; Knohl, A.; Mandic, M.; Jost, H. J. H.

    2016-12-01

    Stable isotopes are a useful tool to provide insights into ecosystem gas exchanges and carbon allocation. The isotopic composition of 13C in respired CO2 for example, has been used to quantify the time lag between assimilation and respiration to be around three days for mature trees. Using the field-deployable Thermo Scientific Delta Ray Isotope Ratio Infrared Spectrometer (IRIS) with automatic calibration, we measured the isotopic composition of 13C and 18O in CO2 in nine inlet heights ranging from 0.1 to 45 m. These measurements were done for a three month period in autumn 2015 in a managed beech forest in Thuringia, Germany. The night-time Keeling-Plot intercept reflecting the 13C and 18O isotopic composition of ecosystem respiration spanned a considerable large range from app. -26 to -32‰ VPDB for 13δC and from app. -8 to -49 VPDP-CO2 for 18δO. Our set up enabled us to calculate Keeling-Plot intercepts with a temporal resolution of 90 minutes accurately with standard errors that had their medians below 0.8 ‰ for both, 13δC and 18δO. The first snow event in fall had a large impact on both delta values of respired CO2. The 18δO value was strongly decreased by app. 30 ‰ and it took 2-3 weeks until the value rose to a similar range than before the snow event. In the case of the 13δC value of ecosystem respiration, we found a qualitatively different behaviour before and after the snow event by analysing the potential meteorological drivers of the 13C composition of respiration. Before the snow event, the 13C signature was significantly correlated to the two-day-sum of radiation two to four days before the measurement. After the first snow event, this correlation vanished abruptly. The time lag of the observed correlation of two to four days is in the expected range for the time lag between assimilation and respiration. To further understand this correlation, we use the multi-layer biosphere-atmosphere model CANOAK to compare the modelled 13δC of

  14. Chlorine isotopic compositions of deep saline fluids in Ibusuki coastal geothermal region, Japan : using B–Cl isotopes to interpret fluid sources

    NARCIS (Netherlands)

    Musashi, Masaaki; Oi, Takao; Kreulen, Rob

    2015-01-01

    We report chlorine stable isotopic compositions (δ37Cl, expressed in ‰ relative to the standard mean ocean chloride) as well as δ2H and δ18O values of deep saline fluids taken at eight drill-holes reaching from 73 to 780 m below sea level in the Ibusuki coastal geothermal region, Japan. Analytical

  15. Chemical and isotopic composition of secondary organic aerosol generated by α-pinene ozonolysis

    DEFF Research Database (Denmark)

    Meusinger, Carl; Dusek, Ulrike; King, Stephanie Michelle

    2017-01-01

    to 400 °C to desorb organic compounds that were (i) detected using PTR-MS for chemical analysis and to determine the O: C ratio, and (ii) converted to CO2 for 13C analysis. More than 400 ions in the mass range 39-800 Da were detected from the desorbed material and quantified using a PTR-MS. The largest......Secondary organic aerosol (SOA) plays a central role in air pollution and climate. However, the description of the sources and mechanisms leading to SOA is elusive despite decades of research. While stable isotope analysis is increasingly used to constrain sources of ambient aerosol, in many cases...... it is difficult to apply because neither the isotopic composition of aerosol precursors nor the fractionation of aerosol forming processes is well characterised. In this paper, SOA formation from ozonolysis of α-pinene - an important precursor and perhaps the best-known model system used in laboratory studies...

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

    Science.gov (United States)

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

    1978-01-01

    The isotopic composition of galactic-cosmic-ray Li, Be, and B has been measured near 100 MeV/nucleon by using the University of Chicago IMP 7 and IMP 8 cosmic-ray telescopes during 1973-1975. The measured abundances allow detailed checks of models of interstellar propagation and solar modulation to be made and conclusions to be drawn concerning the spectral forms at the source and the minimum solar modulation level. For example, comparing these results with local interstellar spectra calculated by using a 'leaky box' model, it is found that if solar modulation is ignored, there is no unique leakage mean free path consistent with all the observations. However, by taking account of a sizable level of residual solar modulation, excellent agreement is obtained between the calculated and measured abundances. Thus, these isotopic abundances confirm the old hypothesis that cosmic-ray Li, Be, and B are produced as secondaries in interstellar space.

  17. Isotopic composition and radiological properties of uranium in selected fuel cycles

    International Nuclear Information System (INIS)

    Fleischman, R.M.; Liikala, R.C.

    1975-04-01

    Three major topic areas are discussed: First, the properties of the uranium isotopes are defined relative to their respective roles in the nuclear fuel cycle. Secondly, the most predominant fuel cycles expected in the U. S. are described. These are the Light Water Reactor (LWR), High Temperature Gas Cooled Reactor (HTGR), and Liquid Metal Fast Breeder Reactor (LMFBR) fuel cycles. The isotopic compositions of uranium and plutonium fuels expected for these fuel cycles are given in some detail. Finally the various waste streams from these fuel cycles are discussed in terms of their relative toxicity. Emphasis is given to the high level waste streams from reprocessing of spent fuel. Wastes from the various fuel cycles are compared based on projected growth patterns for nuclear power and its various components. (U.S.)

  18. Radionuclide content and state of isotopic disequilibrium in some utilized smoking pastes

    Energy Technology Data Exchange (ETDEWEB)

    Shabana, El-Said Ibrahim; Yahya, Ahmad Abu Bakre [King Abdulaziz Univ., Jeddah (Saudi Arabia). Faculty of Engineering, Radiation Protection and Training Centre; Kinsara, Abdulraheem Abdulrahman [King Abdulaziz Univ., Jeddah (Saudi Arabia). Faculty of Engineering, Nuclear Engineering Dept.

    2014-10-01

    {sup 238}U, {sup 234}U, {sup 226}Ra, {sup 210}Pb and {sup 210}Po were measured in some jurak and mehassel samples collected from the local market. Jurak is a paste mixture composed of 30% tobacco, 50% molasses and 20% spices and minced fruits. Mehassel is a local trade-name of a paste mixture of unknown ratios of tobacco to spices and minced fruits. Both jurak and mehassel are used for smoking by Shisha (a pipe used for smoking and has a water filter). Just for comparison, these radionuclides were measured in some cigarette tobacco samples. In cigarette tobacco samples, the average activity concentrations were 0.32 ± 0.10, 0.51 ± 0.11, 3.6 ± 1.0, 16.1 ± 2.4 and 15.8 ± 2.2 Bq/kg for {sup 238}U, {sup 234}U, {sup 226}Ra, {sup 210}Pb and {sup 210}Po, respectively. These values for the same isotopes were 1.01 ± 0.25, 1.04 ± 0.27, 1.2 ± 0.4, 4.4 ± 1.0 and 4.2 ± 0.9 Bq/kg in jurak samples and 0.17 ± 0.07, 0.24 ± 0.08, 1.8 ± 0.7, 7.5 ± 1.7 and 7.0 ± 1.6 Bq/kg in mehassel samples, respectively. Generally, the mean values of the results indicated that, except for uranium in jurak, the activity concentration for all the analyzed radionuclides in the different samples followed the sequence: {sup 210}Po ∼ {sup 210}Pb > {sup 226}Ra >> {sup 234}U > {sup 238}U, whereas for each radionuclide, its activity concentration followed the sequence: cigarette tobacco > mehassel > jurak. Molasses contributed to the enhanced uranium content in jurak samples. The obtained results are discussed in detail.

  19. The Megalopolitan Snowstorm of 11-12 February 1983: Isotopic Composition of the Snow.

    Science.gov (United States)

    Gedzelman, Stanley David; Rosenbaum, Jeffrey Marc; Lawrence, James R.

    1989-06-01

    The stable isotopic composition (D and 18O) of precipitation and water vapor from the megalopolitan snowstorm of 11-12 February 1983 collected in the New York metropolitan area has been related to both synoptic scale and mesoscale structure of the storm. The D increased from a very low value of 242.3%. at the beginning of the storm to a distinct maximum of 85.5% during and shortly after the time that thunder and lightning were reported, then decreased slowly to about 110% The storm-integrated D as measured at Mohonk Lake, New York, was the second lowest value, 170%o, for all storms monitored from 1977 to 1984.The extremely low values throughout most of the storm arose primarily from two effects acting together. A large proportion of condensation took place abnormally high in the troposphere at abnormally low temperatures. The low temperatures increased the amount of isotopic fractionation recurring during the condensation process while the high elevation resulted in source vapor that was extremely fractionated due to prior precipitation. With the exception of the time period surrounding the thunderstorms, a stratiform model accurately predicted the isotopic values of the precipitation using an profile varying sinusoidally with pressure in the cloud.During passage of the thunderstorms, however, stratiform solutions significantly underestimated the values using the sounding derived from the National Meteorological Center analysis. The discrepancies between model calculations and measured isotopic values of precipitation were able to provide a check on the meteorological analyses. The analysis was modified to incorporate the effects of a large-amplitude gravity wave, which passed through the region at this time. Solutions for both a penetrative convection model and one of slantwise convection in an almost symmetrically neutral environment matched observed isotopic precipitation values closely.

  20. Triple oxygen isotope composition of leaf waters in Mpala, central Kenya

    Science.gov (United States)

    Li, Shuning; Levin, Naomi E.; Soderberg, Keir; Dennis, Kate J.; Caylor, Kelly K.

    2017-06-01

    Variations in triple oxygen isotopes have been used in studies of atmospheric photochemistry, global productivity and increasingly in studies of hydroclimate. Understanding the distribution of triple oxygen isotopes in plant waters is critical to studying the fluxes of oxygen isotopes between the atmosphere and hydrosphere, in which plants play an important role. In this paper we report triple oxygen isotope data for stem and leaf waters from Mpala, Kenya and explore how Δ17 O, the deviation from an expected relationship between 17O /16O and 18O /16O ratios, in plant waters vary with respect to relative humidity and deuterium excess (d-excess). We observe significant variation in Δ17 O among waters in leaves and stems from a single plant (up to 0.16‰ range in Δ17 O in leaf water in a plant over the course of a signal day), which correlates to changes in relative humidity. A steady state model for evaporation in leaf water reproduces the majority of variation in Δ17 O and d-excess we observed in leaf waters, except for samples that were collected in the morning, when relative humidity is high and the degree of fractionation in the system is minimal. The data and the steady state model indicate that the slope, λtransp, that links δ17 O and δ18 O values of stem and leaf waters and characterizes the fractionation during transpiration, is strongly influenced by the isotopic composition of ambient vapor when relative humidity is high. We observe a strong, positive relationship between d-excess and Δ17 O, with a slope 2.2 ± 0.2 per meg ‰-1, which is consistent with the observed relationship in tropical rainfall and in water in an evaporating open pan. The strong linear relationship between d-excess and Δ17 O should be typical for any process involving evaporation or any other fractionation that is governed by kinetic effects.

  1. Hydrochemical and Isotopic Composition of The Water Resources In The Po Delta Plain (northern Italy) and Its Environmental Impact

    Science.gov (United States)

    Rapti Caputo, D.; Martinelli, G.

    Groundwater samples from wells were collected to examine the hydrochemical char- acteristics and isotopic composition of the water resources in the Ferrara area (delta Po plain). Electrical conductivity (EC), pH, total dissolved solid (TDS), temperature of the water were directly measured in the field. Subsequently, in the laboratory, the samples were analysed for the determination of major ions such as Ca, Mg, K, Na, SO4, Cl, NO3 and HCO3. Also, oxygen, deuterium and tritium isotopic composition, of the same samples were analysed for the isotopic characterisation of the waters. Three principal water groups can be distinguished on the basis of the distribution of the values of 18O and 2H. The first group (A), include the waters from the wells that exploit the unsatured shallow aquifer, developing in mainly sandy or sandy-silty lenses. These are large diameter wells, whose depth does not exceed the 7 m, while their piezometric level is at depth varying between 2 and 3 m from the soil surface. The isotopic composition of such wells is strongly affected by meteorological events (local recharge). Indeed, the main supply to the aquifer occurs through infiltration, mainly from rainwaters and, secondly, from the waters contained in the drainage channels. The hydrochemical characteristics of the waters coming from those wells present a very high sulphate concentration (up to 508 mg/l). To the second group (B) belong the waters with an 18O and 2H content lower than the previously described group and varying, respectively, between -9.6 < 18O < -9.0 and 68.9 < 2H < -64.7. In partic- ular, this group include the waters from the wells exploiting the first confined aquifer sistem, developed in mainly sandy layers. The top of this hydrogeological units, is at a depth varying between 15 and 20 m from the soil surface, while the thickness varies from 20 and 35 m. The waters of this goup present low oxygen values and deuterium and a substantial variation in the traces of tritium

  2. A survey of Li isotope content in freshwater on a basaltic island of the Galapagos Archipelago

    Science.gov (United States)

    Larsen, W.; Liu, X. M.; Riveros-Iregui, D. A.

    2017-12-01

    Li isotopes in continental surface water fractionate during chemical weathering processes, but their utility as a global paleoenvironmental proxy remains in question. Here we investigate factors controlling Li isotope fractionation in groundwater and streams that drain a single lithology on a basaltic island. Isla San Cristobál, Ecuador has no evidence of hydrothermal activity and is the only island in the Galápagos Archipelago that has permanent sources of fresh water. Multiple perennial streams are located on the windward side of the island, many of which are fed by groundwater springs. We investigate the hydrologic control on Li isotopes in groundwater and streams on San Cristobál to affirm the applicability of Li isotopes as tracers of groundwater residence times and chemical weathering intensity. Water samples were taken from groundwater springs and streams throughout 5 different catchments for Li isotopic analysis. Preliminary analyses show that high elevation (>500m) groundwater springs have an average pH and TDS much closer to that of rainwater than low elevation (200-300m) groundwater springs. This points to a comparatively longer groundwater residence time for low elevation springs with larger Li isotope fractionation. Observing the evolution of the dissolved Li isotopic signal from groundwater through streams to the ocean will provide a valuable comparison to studies conducted on catchments draining similar basaltic lithologies.

  3. Altitude effect on leaf wax carbon isotopic composition in humid tropical forests

    Science.gov (United States)

    Wu, Mong Sin; Feakins, Sarah J.; Martin, Roberta E.; Shenkin, Alexander; Bentley, Lisa Patrick; Blonder, Benjamin; Salinas, Norma; Asner, Gregory P.; Malhi, Yadvinder

    2017-06-01

    The carbon isotopic composition of plant leaf wax biomarkers is commonly used to reconstruct paleoenvironmental conditions. Adding to the limited calibration information available for modern tropical forests, we analyzed plant leaf and leaf wax carbon isotopic compositions in forest canopy trees across a highly biodiverse, 3.3 km elevation gradient on the eastern flank of the Andes Mountains. We sampled the dominant tree species and assessed their relative abundance in each tree community. In total, 405 sunlit canopy leaves were sampled across 129 species and nine forest plots along the elevation profile for bulk leaf and leaf wax n-alkane (C27-C33) concentration and carbon isotopic analyses (δ13C); a subset (76 individuals, 29 species, five forest plots) were additionally analyzed for n-alkanoic acid (C22-C32) concentrations and δ13C. δ13C values display trends of +0.87 ± 0.16‰ km-1 (95% CI, r2 = 0.96, p families, suggesting the biochemical response to environment is robust to taxonomic turnover. We calculate fractionations and compare to adiabatic gradients, environmental variables, leaf wax n-alkane concentrations, and sun/shade position to assess factors influencing foliar chemical response. For the 4 km forested elevation range of the Andes, 4-6‰ higher δ13C values are expected for upland versus lowland C3 plant bulk leaves and their n-alkyl lipids, and we expect this pattern to be a systematic feature of very wet tropical montane environments. This elevation dependency of δ13C values should inform interpretations of sedimentary archives, as 13C-enriched values may derive from C4 grasses, petrogenic inputs or upland C3 plants. Finally, we outline the potential for leaf wax carbon isotopes to trace biomarker sourcing within catchments and for paleoaltimetry.

  4. The tungsten isotopic composition of the Earth's mantle before the terminal bombardment.

    Science.gov (United States)

    Willbold, Matthias; Elliott, Tim; Moorbath, Stephen

    2011-09-07

    Many precious, 'iron-loving' metals, such as gold, are surprisingly abundant in the accessible parts of the Earth, given the efficiency with which core formation should have removed them to the planet's deep interior. One explanation of their over-abundance is a 'late veneer'--a flux of meteorites added to the Earth after core formation as a 'terminal' bombardment that culminated in the cratering of the Moon. Some 3.8 billion-year-old rocks from Isua, Greenland, are derived from sources that retain an isotopic memory of events pre-dating this cataclysmic meteorite shower. These Isua samples thus provide a window on the composition of the Earth before such a late veneer and allow a direct test of its importance in modifying the composition of the planet. Using high-precision (less than 6 parts per million, 2 standard deviations) tungsten isotope analyses of these rocks, here we show that they have a isotopic tungsten ratio (182)W/(184)W that is significantly higher (about 13 parts per million) than modern terrestrial samples. This finding is in good agreement with the expected influence of a late veneer. We also show that alternative interpretations, such as partial remixing of a deep-mantle reservoir formed in the Hadean eon (more than four billion years ago) or core-mantle interaction, do not explain the W isotope data well. The decrease in mantle (182)W/(184)W occurs during the Archean eon (about four to three billion years ago), potentially on the same timescale as a notable decrease in (142)Nd/(144)Nd (refs 3 and 6). We speculate that both observations can be explained if late meteorite bombardment triggered the onset of the current style of mantle convection.

  5. The tungsten isotopic composition of the Earth's mantle before the terminal bombardment

    Science.gov (United States)

    Willbold, Matthias; Elliott, Tim; Moorbath, Stephen

    2011-09-01

    Many precious, `iron-loving' metals, such as gold, are surprisingly abundant in the accessible parts of the Earth, given the efficiency with which core formation should have removed them to the planet's deep interior. One explanation of their over-abundance is a `late veneer'--a flux of meteorites added to the Earth after core formation as a `terminal' bombardment that culminated in the cratering of the Moon. Some 3.8 billion-year-old rocks from Isua, Greenland, are derived from sources that retain an isotopic memory of events pre-dating this cataclysmic meteorite shower. These Isua samples thus provide a window on the composition of the Earth before such a late veneer and allow a direct test of its importance in modifying the composition of the planet. Using high-precision (less than 6 parts per million, 2 standard deviations) tungsten isotope analyses of these rocks, here we show that they have a isotopic tungsten ratio 182W/184W that is significantly higher (about 13 parts per million) than modern terrestrial samples. This finding is in good agreement with the expected influence of a late veneer. We also show that alternative interpretations, such as partial remixing of a deep-mantle reservoir formed in the Hadean eon (more than four billion years ago) or core-mantle interaction, do not explain the W isotope data well. The decrease in mantle 182W/184W occurs during the Archean eon (about four to three billion years ago), potentially on the same timescale as a notable decrease in 142Nd/144Nd (refs 3 and 6). We speculate that both observations can be explained if late meteorite bombardment triggered the onset of the current style of mantle convection.

  6. Controls on the chemical and isotopic compositions of urban stormwater in a semiarid zone

    Science.gov (United States)

    Asaf, L.; Nativ, R.; Shain, D.; Hassan, M.; Geyer, S.

    2004-07-01

    The temporal variations in the chemical and isotopic compositions of urban stormwater under different land uses, and their dependence on physical parameters such as precipitation intensity, stormwater discharge, cumulative stormwater volumes and the size of the drainage area, were investigated in the coastal city of Ashdod, Israel. During 2000/2001 and 2001/2002, 46 stormwater events were intensively monitored for precipitation distribution and intensity at three stations across the city, and for stormwater discharge at seven stations draining 85% of the city area. Sixty-eight and 202 precipitation samples were collected and analyzed for chemical and isotopic compositions, respectively, as were 186 stormwater samples, collected from the drains during 15 of the 46 events. Land use had only a minor effect on the concentrations of major ions and trace elements. Conversely, the concentrations and variety of volatile and semi-volatile organic compounds were significantly higher in stormwater generated in the industrial area than in that draining from residential areas. Ion and trace-metal concentrations were very low (below drinking-water standards) in 97% of the stormwater samples collected from all drains. Stormwater concentrations were higher at stations draining a larger area, thereby linking concentrations to the length of the stormwater flow paths. A first-flush effect was documented on both a seasonal and event basis for both ions and trace elements. The high concentrations of fecal coliform bacteria exceeded the drinking-water standards and displayed a random pattern. The isotopic ratios of oxygen and hydrogen in the stormwater suggest very little exposure to the atmosphere, resulting in very limited fractionation. The presence of fecal coliforms, ammonium in some samples, and specific ratios of oxygen and nitrogen isotopes, suggest that although the sewer and stormwater-collection systems are separated, wastewater, possibly from overflowing sewers, contributed

  7. Strong linkage of polar cod (Boreogadus saida) to sea ice algae-produced carbon: Evidence from stomach content, fatty acid and stable isotope analyses

    Science.gov (United States)

    Kohlbach, Doreen; Schaafsma, Fokje L.; Graeve, Martin; Lebreton, Benoit; Lange, Benjamin Allen; David, Carmen; Vortkamp, Martina; Flores, Hauke

    2017-03-01

    The polar cod (Boreogadus saida) is considered an ecological key species, because it reaches high stock biomasses and constitutes an important carbon source for seabirds and marine mammals in high-Arctic ecosystems. Young polar cod (1-2 years) are often associated with the underside of sea ice. To evaluate the impact of changing Arctic sea ice habitats on polar cod, we examined the diet composition and quantified the contribution of ice algae-produced carbon (αIce) to the carbon budget of polar cod. Young polar cod were sampled in the ice-water interface layer in the central Arctic Ocean during late summer 2012. Diets and carbon sources of these fish were examined using 4 approaches: (1) stomach content analysis, (2) fatty acid (FA) analysis, (3) bulk nitrogen and carbon stable isotope analysis (BSIA) and (4) compound-specific stable isotope analysis (CSIA) of FAs. The ice-associated (sympagic) amphipod Apherusa glacialis dominated the stomach contents by mass, indicating a high importance of sympagic fauna in young polar cod diets. The biomass of food measured in stomachs implied constant feeding at daily rates of ∼1.2% body mass per fish, indicating the potential for positive growth. FA profiles of polar cod indicated that diatoms were the primary carbon source, indirectly obtained via amphipods and copepods. The αIce using bulk isotope data from muscle was estimated to be >90%. In comparison, αIce based on CSIA ranged from 34 to 65%, with the highest estimates from muscle and the lowest from liver tissue. Overall, our results indicate a strong dependency of polar cod on ice-algae produced carbon. This suggests that young polar cod may be particularly vulnerable to changes in the distribution and structure of sea ice habitats. Due to the ecological key role of polar cod, changes at the base of the sea ice-associated food web are likely to affect the higher trophic levels of high-Arctic ecosystems.

  8. Sulphur isotopic and chemical compositions of the natural waters in the Chuncheon area, Korea

    International Nuclear Information System (INIS)

    Yu, Jae-Young; Park, Youngyun

    2004-01-01

    The contribution of Chinese sources to the acid deposition in neighbouring countries in Far East Asia has been disputed. This study is to examine the isotopic composition of the S in the natural waters in the Chuncheon area to see if the isotopic composition can be an indicator of the pollution sources in the area. Meteoric water sampled between September 2000 and July 2001 and surface water sampled in December 2000 and April 2001 in the area were collected to examine their chemical and isotopic compositions. The pH values of the meteoric water lie between 4.02 and 6.89, but mostly lower than 5.6, indicating considerable acid deposition. The pH of the surface water is generally higher than that of the atmospheric water. Factor analysis on the concentrations of the dissolved components suggests that the surface water chemistry depends principally on the chemistry of the atmospheric water. The dissolution of carbonate minerals and silicate-water interaction plays a rather minor role in affecting the water chemistry. δ 18 O and δD of all the natural water samples align fairly well along the global meteoric water line. The δ 34 S of the dissolved SO 4 in the meteoric water has values ranging from 3.4 to 8.2 per mille, showing little seasonal difference. The contribution from sea-salt to the total atmospheric S is estimated to be less than 10%. The δ 34 S of the anthropogenic S in the Chuncheon atmosphere is calculated to be 2.5 to 7.2 per mille, which partly overlaps the reported values of S in Chinese coal, Chinese rainfall, and Japanese fallout. Appropriate tracking and quantitative estimation of the contribution from possible pollution sources to the local S concentrations requires more information on the isotopic compositions of the potential pollution sources. The δ 34 S of the dissolved SO 4 in the surface water has values ranging from 3.2 to 6.2 per mille, which is a little narrower than that of the meteoric water. The δ 34 S and the concentration range of

  9. High temporal resolution measurements of the isotopic composition of CH4 at the Lutjewad station, The Netherlands

    Science.gov (United States)

    Röckmann, Thomas; van der Veen, Carina; Chen, Huilin; Scheeren, Bert

    2017-04-01

    Isotope measurements can help constraining the atmospheric budget of the greenhouse gas methane (CH4) because different sources emit CH4 with slightly different isotopic composition. In the past, high precision isotope measurements have primarily been carried out by isotope ratio mass spectrometry on flask samples that are usually collected at relatively low temporal resolution. We have recently developed a fully automated gas chromatography - isotope ratio mass spectrometry system (GC-IRMS) for autonomous and unattended CH4 isotope measurements (δD and δ13C) in the field. The first deployment at the Cabauw Experimental Site for Atmospheric Research (CESAR) indicated that CH4 emissions from fossil fuel sources are overestimated in this region [1]. To further exploit the potential of this approach, the in situ system has been installed in November 2016 at the Lutjewad atmospheric monitoring and sampling site in the North of the Netherlands. This site is expected to sample also emissions from the large Groningen gas fields. The isotope measurements are expected to allow distinguishing these emissions from the agricultural emissions, which are also strong in this region. We will present the results from these ongoing measurements of δD and δ13C in CH4.. 1. Röckmann, T., et al., In situ observations of the isotopic composition of methane at the Cabauw tall tower site, Atmos. Chem. Phys., 2016. 16: 10469-10487.

  10. Rapid, high-precision measurements of boron isotopic compositions in marine carbonates.

    Science.gov (United States)

    McCulloch, Malcolm T; Holcomb, Michael; Rankenburg, Kai; Trotter, Julie A

    2014-12-30

    The isotopic composition and elemental abundance of boron (B) in marine carbonates provide a powerful tool for tracking changes in seawater pH and carbonate chemistry. Progress in this field has, however, been hampered by the volatile nature of B, its persistent memory, and other uncertainties associated with conventional chemical extraction and mass spectrometric measurements. Here we show that for marine carbonates, these limitations can be overcome by using a simplified, low-blank, chemical extraction technique combined with robust multi-collector inductively couple plasma mass spectrometry (MC-ICPMS) methods. Samples are dissolved in dilute HNO3 and loaded first onto on a cation-exchange column with the major cations (Ca, Mg, Sr, Na) being quantitatively retained while the B fraction is carried in the eluent. The eluent is then passed directly through an anion column ensuring that any residual anions, such as SO4(2-), are removed. Isotopic measurements of (11)B/(10)B ratios are undertaken by matching both the B concentration and the isotopic compositions of the samples with the bracketing standard, thereby minimising corrections for cross-contamination. The veracity of the MC-ICPMS procedure is demonstrated using a gravimetrically prepared laboratory standard, UWA24.7, relative to the international reference standard NIST SRM 951 (δ(11)B = 0‰). This gives values consistent with gravimetry (δ(11)B = 24.7 ± 0.3‰ 2sd) for solutions ranging in concentration from 50 to 500 ppb, equivalent to ~2-10 mg size coral samples. The overall integrity of the method for carbonate analysis is demonstrated by measurements of the international carbonate standard JCp-1 (δ(11)B = 24.3 ± 0.34‰ 2sd). A streamlined, integrated approach is described here that enables rapid, accurate, high-precision measurements of boron isotopic compositions and elemental abundances in commonly analysed biogenic carbonates, such as corals, bivalves, and large benthic forams. The overall

  11. Titanium isotopic compositions of rare presolar SiC grain types from the Murchison meteorite

    Science.gov (United States)

    Nguyen, Ann N.; Nittler, Larry R.; Alexander, Conel M. O'D.; Hoppe, Peter

    2018-01-01

    We report the Ti isotopic compositions of 8 mainstream, 22 Y, 9 Z, and 26 AB presolar SiC grains from two SiC-rich residues of the Murchison CM2 meteorite together with Si, C and some Mg-Al isotopic data for the same grains. Mainstream, Y and Z grains are believed to originate in asymptotic giant branch (AGB) stars of varying metallicities, but the stellar sources of AB grains are poorly understood. We find that the 46,47,49Ti/48Ti ratios are correlated with 29Si/28Si for all of the grain types, indicating that these ratios are mainly dominated by Galactic chemical evolution (GCE). The mainstream, Y and Z grains all show enrichments in 50Ti from neutron capture nucleosynthesis. However, AGB models predict smaller excesses in 50Ti (and 49Ti) than are observed in these grains. For Z grains and especially for Y grains, the enhancement of 50Ti is greater than the enhancement in 30Si, indicating that the 13C neutron source produced a greater total fluence of neutrons than the 22Ne source in the low metallicity parent AGB stars. The Z grains plot below the mainstream correlation lines at more 48Ti- and 28Si-rich compositions in plots of 46,47,49Ti/48Ti vs. 29Si/28Si. On the other hand, the Y grains plot close to the mainstream correlation line. This could imply that the Ti isotopes evolved non-linearly at metallicities below ∼1/3 solar. The AB grains in this study have Ti isotopic compositions that fall along correlation lines defined by the mainstream grains, suggesting origins in close to solar metallicity stars. However, these grains fall below the mainstream correlation lines in plots of 46,49,50Ti/48Ti vs. 29Si/28Si and do not show enhancements in 50Ti, indicating that their parent stars did not undergo significant s-process nucleosynthesis. These data support origins of AB grains in J-type C stars rather than born-again AGB stars that undergo s-process nucleosynthesis. AB grains that do not have 50Ti excesses may provide the best measure of Si and Ti isotope GCE

  12. Effect of composition on diffusible hydrogen content and hydrogen assisted cracking of steel welds

    International Nuclear Information System (INIS)

    Albert, S.K.; Ramasubbu, V.; Bhaduri, A.K.; Parvathavarthini, N.

    2008-01-01

    Study of hydrogen assisted cracking and measurement of diffusible hydrogen content in different Cr-Mo steel welds showed that for identical conditions, susceptibility to cracking increased and diffusible hydrogen content decreased with increase in alloy content. Hydrogen permeation studies showed that hydrogen diffusivity decreases and solubility increases with increase in alloy content. Thus decrease in diffusible hydrogen content with increase in alloying is attributed to increase in apparent solubility and decrease in apparent diffusivity of hydrogen with increase in alloy content. Analysis of the results indicates that variation of diffusible hydrogen content and apparent diffusivity of hydrogen with alloy content can be represented as a function of alloy composition. (author)

  13. The isotope method for the determination of stoichiometry between compounds forming the polypyrrole and glucose oxidase composite.

    Science.gov (United States)

    Garbaras, A; Mikoliunaite, L; Popov, A; Ramanaviciene, A; Remeikis, V; Ramanavicius, A

    2015-01-21

    Stable isotope ratio mass spectrometry is a conventional method used in archaeology, and medical, environmental and paleoenvironmental reconstruction studies. However new insights and applicability of the equipment often open new research areas and improve our understanding of the ongoing processes. Therefore the stable isotope ratio mass spectrometry method was applied for the stoichiometry determination of the complex polypyrrole and glucose oxidase composite (PPy-GOx composite). The enzyme glucose oxidase and conducting polymer polypyrrole were reported to form a composite, which was evaluated in time using the dynamic light scattering method. The consistent enlargement of the PPy-GOx composite and the relative decrease of the spare enzyme molecules were observed in the polymerization solution. UV-VIS spectrometry was employed to follow the polymerization process. The isotope mixing model was applied for the evaluation of the constitution of the PPy-GOx composite. According to the obtained results the determination of the PPy-GOx composite stoichiometry could be more reliably determined using the nitrogen isotope ratio approach in comparison to the carbon approach. We expect that this novel work will widen the applications of stable isotope ratio mass spectrometry in research.

  14. The effect of the isotopic composition of oxygen on the non-mass-dependent isotopic fractionation in the formation of ozone by discharge of O2. [from meteorites

    Science.gov (United States)

    Yang, Jongmann; Epstein, Samuel

    1987-01-01

    Isotopic fractionation processes in the formation of O3 by 20-kV 60-kHz discharge of O2 in a fused silica container at 77 K are investigated experimentally, with a focus on the effects of changes in the isotopic composition of O2, the O2 pressure, the degree of O3 formation, and the discharge geometry on the isotope abundances in the postdischarge O2 and O3. The results are presented in tables and graphs and compared with the predictions of theoretical models involving vibrational anharmonicity and symmetry effects on O3 predissociation. In experiments using O2 enriched with O-17 and O-18, the heavy isotope is enriched in the residual O2 and not in the O3, whereas the opposite is true when atmospheric isotope abundances are used. It is inferred that the predissociation rate depends on the symmetry and mass of the O3 molecules and not on self-shielding or symmetry effects in the reactant O2. The potential value of the present findings for studies of anomalous isotope abundances in meteorites is indicated.

  15. Characterisation and origin of hydrothermal waters at São Miguel (Azores) inferred by chemical and isotopic composition

    Science.gov (United States)

    Woitischek, Julia; Dietzel, Martin; Inguaggiato, Claudio; Böttcher, Michael E.; Leis, Albrecht; Cruz, J. Virgílio; Gehre, Matthias

    2017-10-01

    This study focuses on the characterisation and origin of hydrothermal waters discharging from three main active volcanoes (Furnas, Fogo and Sete Cidades) at São Miguel, where 33 water with temperatures ranging between 13 and 97 °C, and 5 precipitate samples were collected. The developed conceptual model for this active hydrothermal system reveals that all waters can be classified by Na-HCO3, Na-Cl and Na-SO4 types and are of meteoric origin. This is confirmed by the stable hydrogen and oxygen isotope data that are positioned close to the local meteoric water line (- 4.1‰ ≤ δ18OH2O ≤ 5.2‰; - 17.6‰ ≤ δDH2O ≤ 20.4‰), except for the Na-Cl type water at Ferraria (Sete Cidades area), which is characterized by admixing of seawater. The stable isotope composition of São Miguel hydrothermal solutions (δ34SSO4 range from 21.3 to - 3.7; δ18OSO4 range between 0.5 and 10.5‰; δ13CTDIC = - 4.5 ± 3.2‰) indicate that waters are individually evolved by several processes: evaporation, uptake of volcanogenic sulphur and carbon dioxide, leaching of local volcanic rocks (driven by high CO2 contents and/or elevated temperature), and biological activity. Latter hydrochemical superimposition is displayed by stromatolitic structures in the precipitates at the given site. Dissolved REE data show similar pattern as local volcanic rocks. In particular the distinct Eu anomaly hints to preferential leaching of locally occurring trachyte. The strongly acidic Na-SO4 waters sampled in boiling pools at Fogo and Furnas Lake indicate high leaching levels and LREE depletion versus HREE compared with the volcanic local rock compositions. Depletion in LREE is most likely caused by its preferential removal compared to HREE by the co-precipitation with alunite.

  16. Insights From Magnesium Isotopic Compositions on the Oceanic Hydrothermal Circulation: Is Seamount Weathering the Solution?

    Science.gov (United States)

    Galy, A.; Carder, E.; Elderfield, H.

    2006-12-01

    It has been long recognised that the input of Mg in the ocean by river is removed by precipitation of Mg-rich bearing phases, either directly from the ocean such as dolomite or through hydrothermal circulation in the oceanic crust. The sampling of hydrothermal fluids demonstrated the efficiency of Mg consumption by the alteration of the oceanic crust, even at temperatures as low as 15°. For high-temperature fluids vented through black or white smokers in the vicinity of the ridge, the Mg concentration is up to 50 time lower than in seawater, and the close relationship between chlorine and Mg led to the idea that seawater was feeding the hydrothermal system and that Mg is quantitatively removed from it during high-T° alteration, the so called zero Mg hypothesis. Despite some hint for a non zero Mg hydrothermal end-member for a handful sites, the low concentration of Mg in oceanic hydrothermal fluids (around 1 mmol/l) has been mainly attributed to contamination by seawater during the sampling. Here we present Mg isotopic composition of 14 seawater samples from the Atlantic, Pacific and Indian Oceans and the Mediterranean and Red Seas and covering a range of depth of almost 5km and 26 hydrothermal fluids from 7 sites in the Atlantic and Pacific Oceans with temperature from 15° to 380°C. We find the magnesium isotope composition of seawater to be constant, with a δ^{26}Mg = -0.82±0.10 ‰ relative to the DSM3 standard. This value is consistent with a long residence time for Mg in seawater. In addition, out of the 26 hydrothermal fluids studied, more than 58% differ from seawater for their Mg isotopic composition by more than 2σ. This number rises up to 88% at 2σmean level and the shift is systematic with the fluids being either indistinguishable from seawater or enriched in light isotopes by up to 2.4‰ in δ^{26}Mg. This clearly demonstrates that fluids having low Mg concentrations are not solely bearing Mg added by contamination during sampling. The isotopic

  17. Effect of amino acids on the precipitation kinetics and Ca isotopic composition of gypsum

    Science.gov (United States)

    Harouaka, Khadouja; Kubicki, James D.; Fantle, Matthew S.

    2017-12-01

    Stirred gypsum (CaSO4 · 2H2O) precipitation experiments (initial Ωgypsum = 2.4 ± 0.14, duration ≈ 1.0-1.5 h) were conducted in the presence of the amino acids glycine (190 μM), L-alanine (190 μM), D- and L-arginine (45 μM), and L-tyrosine (200 μM) to investigate the effect of simple organic compounds on both the precipitation kinetics and Ca isotopic composition of gypsum. Relative to abiotic controls, glycine, tyrosine, and alanine inhibited precipitation rates by ∼22%, 27%, and 29%, respectively, while L- and D-arginine accelerated crystal growth by ∼8% and 48%, respectively. With the exception of tyrosine, amino acid induced inhibition resulted in fractionation factors (αs-f) associated with precipitation that were no more than 0.3‰ lower than amino acid-free controls. In contrast, the tyrosine and D- and L-arginine experiments had αs-f values associated with precipitation that were similar to the controls. Our experimental results indicate that Ca isotopic fractionation associated with gypsum precipitation is impacted by growth inhibition in the presence of amino acids. Specifically, we propose that the surface-specific binding of amino acids to gypsum can change the equilibrium fractionation factor of the bulk mineral. We investigate the hypothesis that amino acids can influence the growth of gypsum at specific crystal faces via adsorption and that different faces have distinct fractionation factors (αface-fluid). Accordingly, preferential sorption of amino acids at particular faces changes the relative, face-specific mass fluxes of Ca during growth, which influences the bulk isotopic composition of the mineral. Density functional theory (DFT) calculations suggest that the energetic favorability of glycine sorption onto gypsum crystal faces occurs in the order: (1 1 0) > (0 1 0) > (1 2 0) > (0 1 1), while glycine sorption onto the (-1 1 1) face was found to be energetically unfavorable. Face-specific fractionation factors constrained by

  18. Technical note: An inverse method to relate organic carbon reactivity to isotope composition from serial oxidation

    Science.gov (United States)

    Hemingway, Jordon D.; Rothman, Daniel H.; Rosengard, Sarah Z.; Galy, Valier V.

    2017-11-01

    Serial oxidation coupled with stable carbon and radiocarbon analysis of sequentially evolved CO2 is a promising method to characterize the relationship between organic carbon (OC) chemical composition, source, and residence time in the environment. However, observed decay profiles depend on experimental conditions and oxidation pathway. It is therefore necessary to properly assess serial oxidation kinetics before utilizing decay profiles as a measure of OC reactivity. We present a regularized inverse method to estimate the distribution of OC activation energy (E), a proxy for bond strength, using serial oxidation. Here, we apply this method to ramped temperature pyrolysis or oxidation (RPO) analysis but note that this approach is broadly applicable to any serial oxidation technique. RPO analysis directly compares thermal reactivity to isotope composition by determining the E range for OC decaying within each temperature interval over which CO2 is collected. By analyzing a decarbonated test sample at multiple masses and oven ramp rates, we show that OC decay during RPO analysis follows a superposition of parallel first-order kinetics and that resulting E distributions are independent of experimental conditions. We therefore propose the E distribution as a novel proxy to describe OC thermal reactivity and suggest that E vs. isotope relationships can provide new insight into the compositional controls on OC source and residence time.

  19. Tracing changes in atmospheric sources of lead contamination using lead isotopic compositions in Australian red wine.

    Science.gov (United States)

    Kristensen, Louise Jane; Taylor, Mark Patrick; Evans, Andrew James

    2016-07-01

    Air quality data detailing changes to atmospheric composition from Australia's leaded petrol consumption is spatially and temporally limited. In order to address this data gap, wine was investigated as a potential proxy for atmospheric lead conditions. Wine spanning sixty years was collected from two wine regions proximal to the South Australian capital city, Adelaide, and analysed for lead concentration and lead and strontium isotopic composition for source apportionment. Maximum wine lead concentrations (328 μg/L) occur prior to the lead-in-air monitoring in South Australia in the later 1970s. Wine lead concentrations mirror available lead-in-air measurements and show a declining trend reflecting parallel reductions in leaded petrol emissions. Lead from petrol dominated the lead in wine ((206)Pb/(207)Pb: 1.086; (208)Pb/(207)Pb: 2.360) until the introduction of unleaded petrol, which resulted in a shift in the wine lead isotopic composition closer to vineyard soil ((206)Pb/(207)Pb: 1.137; (208)Pb/(207)Pb: 2.421). Current mining activities or vinification processes appear to have no impact with recent wine samples containing less than 4 μg/L of lead. This study demonstrates wine can be used to chronicle changes in environmental lead emissions and is an effective proxy for atmospherically sourced depositions of lead in the absence of air quality data. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Comparisons of Neutron Cross Sections and Isotopic Composition Calculations for Fission-Product Evaluations

    Science.gov (United States)

    Kim, Do Heon; Gil, Choong-Sup; Chang, Jonghwa; Lee, Yong-Deok

    2005-05-01

    The neutron absorption cross sections for 18 fission products evaluated within the framework of the KAERI (Korea Atomic Energy Research Institute)-BNL (Brookhaven National Laboratory) international collaboration have been compared with ENDF/B-VI.7. Also, the influence of the new evaluations on the isotopic composition calculations of the fission products has been estimated through the OECD/NEA burnup credit criticality benchmarks (Phase 1B) and the LWR/Pu recycling benchmarks. These calculations were performed by WIMSD-5B with the 69-group libraries prepared from three evaluated nuclear data libraries: ENDF/B-VI.7, ENDF/B-VI.8 including the new evaluations in the resonance region covering the thermal region, and the expected ENDF/B-VII including those in the upper resonance region up to 20 MeV. For Xe-131, the composition calculated with ENDF/B-VI.8 shows a maximum difference of 5.02% compared to ENDF/B-VI.7. However, the isotopic compositions of all the fission products calculated with the expected ENDF/B-VII show no differences when compared to ENDF/B-VI.7 for the thermal reactor benchmark cases.

  1. Technical note: An inverse method to relate organic carbon reactivity to isotope composition from serial oxidation

    Directory of Open Access Journals (Sweden)

    J. D. Hemingway

    2017-11-01

    Full Text Available Serial oxidation coupled with stable carbon and radiocarbon analysis of sequentially evolved CO2 is a promising method to characterize the relationship between organic carbon (OC chemical composition, source, and residence time in the environment. However, observed decay profiles depend on experimental conditions and oxidation pathway. It is therefore necessary to properly assess serial oxidation kinetics before utilizing decay profiles as a measure of OC reactivity. We present a regularized inverse method to estimate the distribution of OC activation energy (E, a proxy for bond strength, using serial oxidation. Here, we apply this method to ramped temperature pyrolysis or oxidation (RPO analysis but note that this approach is broadly applicable to any serial oxidation technique. RPO analysis directly compares thermal reactivity to isotope composition by determining the E range for OC decaying within each temperature interval over which CO2 is collected. By analyzing a decarbonated test sample at multiple masses and oven ramp rates, we show that OC decay during RPO analysis follows a superposition of parallel first-order kinetics and that resulting E distributions are independent of experimental conditions. We therefore propose the E distribution as a novel proxy to describe OC thermal reactivity and suggest that E vs. isotope relationships can provide new insight into the compositional controls on OC source and residence time.

  2. Changes in fatty acid content and composition in silage maize during grain filling

    NARCIS (Netherlands)

    Khan, N.A.; Cone, J.W.; Pellikaan, W.F.; Khan, M.A.; Struik, P.C.; Hendriks, W.H.

    2011-01-01

    Background: The stage of maturity at harvest has a major effect on the fatty acid (FA) content and composition of forage plants consumed by dairy cows. The present study investigated the dynamics of FA content and composition in stover (leaves and stem) and ears (cob, shank and husks) of two maize

  3. Oxygen and carbon isotope composition of Quaternary bivalve shells as a water mass indicator: Last interglacial and Holocene, East Greenland

    DEFF Research Database (Denmark)

    Israelson, C.; Buchardt, Bjørn; Funder, S.V.

    1994-01-01

    Oxygen and carhon isotope composition of arctic bivahe shells are used in an attempt to reCO'1struct -.urface water temperature and salinities in Scoresby Sund. East Greenland. The oxygen i:;otope compositions or .1,tw mllicuf£!. Hialclla arctica and Tridmlla hOl'm!is han~ been compared with pres...

  4. Derivation of correction factor to be applied for calculated results of PWR fuel isotopic composition by ORIGEN2 code

    Energy Technology Data Exchange (ETDEWEB)

    Suyama, Kenya; Nomura, Yasushi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Murazaki, Minoru [Tokyo Nuclear Service Inc., Tokyo (Japan); Mochizuki, Hiroki [The Japan Research Institute Ltd., Tokyo (Japan)

    2001-11-01

    For providing conservative PWR spent fuel compositions from the view point of nuclear criticality safety, correction factors applicable for result of burnup calculation by ORIGEN2 were evaluated. Its conservativeness was verified by criticality calculations using MVP. To calculate these correction factors, analyses of spent fuel isotopic composition data were performed by ORIGEN2. Maximum or minimum value of the ratio of calculation result to experimental data was chosen as correction factor. These factors are given to each set of fuel assembly and ORIGEN2 library. They could be considered as the re-definition of recommended isotopic composition given in Nuclear Criticality Safety Handbook. (author)

  5. The Oxygen Isotope Composition of Dark Inclusions in HEDs, Ordinary and Carbonaceous Chondrites

    Science.gov (United States)

    Greenwood, R. C.; Zolensky, M. E.; Buchanan, P. C.; Franchi, I. A.

    2015-01-01

    Dark inclusions (DIs) are lithic fragments that form a volumetrically small, but important, component in carbonaceous chondrites. Carbonaceous clasts similar to DIs are also found in some ordinary chondrites and HEDs. DIs are of particular interest because they provide a record of nebular and planetary processes distinct from that of their host meteorite. DIs may be representative of the material that delivered water and other volatiles to early Earth as a late veneer. Here we focus on the oxygen isotopic composition of DIs in a variety of settings with the aim of understanding their formational history and relationship to the enclosing host meteorite.

  6. Concentration and isotope composition of atmospheric methane in Walbrzych Coal District

    International Nuclear Information System (INIS)

    Korus, A.; Necki, J.; Kotarba, M.

    2002-01-01

    The closure of hard coal mines in the Walbrzych Coal District led to the reconstruction of carboniferous groundwater horizon and migration of carbon dioxide and methane upward to the surface. Migration of methane is facilitated by systems of fractures, faults and by dense network of shafts, which still remain in connection with the surface. Measurement of the isotopic composition (δ 13 CH 4 ) of methane together with its concentration in atmosphere, yield useful information on the contribution of anthropogenic sources to regional budget of methane. A two component-mixing model was applied to distinguish anthropogenic source. The result of the study, current parameters of anthropogenic source are presented. (author)

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

    OpenAIRE

    Marschall, H.R.; Wanless, V.D.; Shimizu, N.; Pogge von Strandmann, Philip A.E.; Elliott, T.; Monteleone, B.D.

    2017-01-01

    A global selection of 56 mid-ocean ridge basalt (MORB) glasses were analysed for Li and B abundances and isotopic compositions. Analytical accuracy and precision of analyses constitute an improvement over previously published MORB data and allow a more detailed discussion of the Li and B systematics of the crust-mantle system. Refined estimates for primitive mantle abundances ([Li]=1.39±0.10[Li]=1.39±0.10 μg/g and [B]=0.19±0.02[B]=0.19±0.02 μg/g) and depleted mantle abundances ([Li]=1.20±0.10...

  8. Fatty acid and cholesterol content, chemical composition and ...

    African Journals Online (AJOL)

    This study aimed to determine the fatty acid and chemical composition and cholesterol concentration of horsemeat, and to evaluate its taste acceptability by the Brazilian population. Horsemeat samples (M. longissimus dorsi) were obtained from a Paraná State slaughterhouse. The chemical composition revealed a low lipid ...

  9. Primary magmas and mantle sources of Emeishan basalts constrained from major element, trace element and Pb isotope compositions of olivine-hosted melt inclusions

    Science.gov (United States)

    Ren, Zhong-Yuan; Wu, Ya-Dong; Zhang, Le; Nichols, Alexander R. L.; Hong, Lu-Bing; Zhang, Yin-Hui; Zhang, Yan; Liu, Jian-Qiang; Xu, Yi-Gang

    2017-07-01

    Olivine-hosted melt inclusions within lava retain important information regarding the lava's primary magma compositions and mantle sources. Thus, they can be used to infer the nature of the mantle sources of large igneous provinces, which is still not well known and of the subject of debate. We have analysed the chemical compositions and Pb isotopic ratios of olivine-hosted melt inclusions in the Dali picrites, Emeishan Large Igneous Province (LIP), SW China. These are the first in-situ Pb isotope data measured for melt inclusions found in the Emeishan picrites and allow new constraints to be placed on the source lithology of the Emeishan LIP. The melt inclusions show chemical compositional variations, spanning low-, intermediate- and high-Ti compositions, while their host whole rocks are restricted to the intermediate-Ti compositions. Together with the relatively constant Pb isotope ratios of the melt inclusions, the compositional variations suggest that the low-, intermediate- and high-Ti melts were derived from compositionally similar sources. The geochemical characteristics of melt inclusions, their host olivines, and whole-rocks from the Emeishan LIP indicate that Ca, Al, Mn, Yb, and Lu behave compatibly, and Ti, Rb, Sr, Zr, and Nb behave incompatibly during partial melting, requiring a pyroxenite source for the Emeishin LIP. The wide range of Ti contents in the melt inclusions and whole-rocks of the Emeishan basalts reflects different degrees of partial melting in the pyroxenite source at different depths in the melting column. The Pb isotope compositions of the melt inclusions and the OIB-like trace element compositions of the Emeishan basalts imply that mixing of a recycled ancient oceanic crust (EM1-like) component with a peridotite component from the lower mantle (FOZO-like component) could have underwent solid-state reaction, producing a secondary pyroxenite source that was subsequently partially melted to form the basalts. This new model of pyroxenite

  10. Quantification and analysis of deuterium and oxygen-18 isotope composition of precipitation at the southern foothills of Mt. Kilimanjaro (Tanzania)

    Science.gov (United States)

    Otte, Insa; Detsch, Florian; Appelhans, Tim; Nauss, Thomas

    2015-04-01

    analysis. Variations in isotopic content were noted. The 24 month weekly dataset for the entire research area gives the following regression: δ2H = 7.55 δ18O + 15.41, altering to δ2H = 7.20 δ18O + 12.76 during the intensive campaign in December 2013 and to δ2H = 7.31 δ18O + 15.74 during the second intensive campaign in April 2014. The isotopic composition between mean fog water deposition and mean rainfall samples shows variations along the elevation gradient with 7o δ18O and 34o δ2H for lower montane forest (1,800 m a.s.l.) and 18o δ18O and 32o δ2H in 3,800 m a.s.l.. Furthermore, deuterium & oxygen-18 isotope composition will be used to interpret the importance of local evaporation as a significant resource for fog and rainfall (recycling hypothesis) to analyse if local land-cover change will likely have a negative effect on the atmospheric water input. If fog and rainfall is primarily fed by remote water sources, local land-cover changes might enhance rainfall (convection hypothesis).

  11. Abnormal lithium isotope composition from the ancient lithospheric mantle beneath the North China Craton.

    Science.gov (United States)

    Tang, Yan-Jie; Zhang, Hong-Fu; Deloule, Etienne; Su, Ben-Xun; Ying, Ji-Feng; Santosh, M; Xiao, Yan

    2014-03-04

    Lithium elemental and isotopic compositions of olivines in peridotite xenoliths from Hebi in the North China Craton provide direct evidence for the highly variable δ(7)Li in Archean lithospheric mantle. The δ(7)Li in the cores of olivines from the Hebi high-Mg# peridotites (Fo > 91) show extreme variation from -27 to +21, in marked deviation from the δ(7)Li range of fresh MORB (+1.6 to +5.6) although the Li abundances of the olivines are within the range of normal mantle (1-2 ppm). The Li abundances and δ(7)Li characteristics of the Hebi olivines could not have been produced by recent diffusive-driven isotopic fractionation of Li and therefore the δ(7)Li in the cores of these olivines record the isotopic signature of the subcontinental lithospheric mantle. Our data demonstrate that abnormal δ(7)Li may be preserved in the ancient lithospheric mantle as observed in our study from the central North China Craton, which suggest that the subcontinental lithospheric mantle has experienced modification of fluid/melt derived from recycled oceanic crust.

  12. Validation of the scale system for PWR spent fuel isotopic composition analyses

    Energy Technology Data Exchange (ETDEWEB)

    Hermann, O.W.; Bowman, S.M.; Parks, C.V. [Oak Ridge National Lab., TN (United States); Brady, M.C. [Sandia National Laboratories, Las Vegas, NV (United States)

    1995-03-01

    The validity of the computation of pressurized-water-reactor (PWR) spent fuel isotopic composition by the SCALE system depletion analysis was assessed using data presented in the report. Radiochemical measurements and SCALE/SAS2H computations of depleted fuel isotopics were compared with 19 benchmark-problem samples from Calvert Cliffs Unit 1, H. B. Robinson Unit 2, and Obrigheim PWRs. Even though not exhaustive in scope, the validation included comparison of predicted and measured concentrations for 14 actinides and 37 fission and activation products. The basic method by which the SAS2H control module applies the neutron transport treatment and point-depletion methods of SCALE functional modules (XSDRNPM-S, NITAWL-II, BONAMI, and ORIGEN-S) is described in the report. Also, the reactor fuel design data, the operating histories, and the isotopic measurements for all cases are included in detail. The underlying radiochemical assays were conducted by the Materials Characterization. Center at Pacific Northwest Laboratory as part of the Approved Testing Material program and by four different laboratories in Europe on samples processed at the Karlsruhe Reprocessing Plant.

  13. Characterizing the oxygen isotopic composition of phosphate sources to aquatic ecosystems

    Science.gov (United States)

    Young, M.B.; McLaughlin, K.; Kendall, C.; Stringfellow, W.; Rollog, M.; Elsbury, K.; Donald, E.; Paytan, A.

    2009-01-01

    The oxygen isotopic composition of dissolved inorganic phosphate (δ18Op) in many aquatic ecosystems is not in isotopic equilibrium with ambient water and, therefore, may reflect the source δ18Op. Identification of phosphate sources to water bodies is critical for designing best management practices for phosphate load reduction to control eutrophication. In order for δ18O p to be a useful tool for source tracking, the δ18Op of phosphate sources must be distinguishable from one another; however, the δ18Op of potential sources has not been well characterized. We measured the δ18O p of a variety of known phosphate sources, including fertilizers, semiprocessed phosphorite ore, particulate aerosols, detergents, leachates of vegetation, soil, animal feces, and wastewater treatment plant effluent. We found a considerable range of δ18Op values (from +8.4 to +24.9‰) for the various sources, and statistically significant differences were found between several of the source types. δ18Op measured in three different fresh water systems was generally not in equilibrium with ambient water. Although there is overlap in δ18Op values among the groups of samples, our results indicate that some sources are isotopically distinct and δ18Op can be used for identifying phosphate sources to aquatic systems.

  14. Characterizing the oxygen isotopic composition of phosphate sources to aquatic ecosystems.

    Science.gov (United States)

    Young, Megan B; McLaughlin, Karen; Kendall, Carol; Stringfellow, William; Rollog, Mark; Elsbury, Katy; Donald, Elizabeth; Paytan, Adina

    2009-07-15

    The oxygen isotopic composition of dissolved inorganic phosphate (delta18Op) in many aquatic ecosystems is not in isotopic equilibrium with ambient water and, therefore, may reflect the source delta18Op. Identification of phosphate sources to water bodies is critical for designing best management practices for phosphate load reduction to control eutrophication. In order for delta18Op to be a useful tool for source tracking, the delta18Op of phosphate sources must be distinguishable from one another; however, the delta18Op of potential sources has not been well characterized. We measured the delta18Op of a variety of known phosphate sources, including fertilizers, semiprocessed phosphorite ore, particulate aerosols, detergents, leachates of vegetation, soil, animal feces, and wastewater treatment plant effluent. We found a considerable range of delta18Op, values (from +8.4 to +24.9 per thousand) for the various sources, and statistically significant differences were found between several of the source types. delta18Op measured in three different fresh water systems was generally not in equilibrium with ambient water. Although there is overlap in delta18Op values among the groups of samples, our results indicate that some sources are isotopically distinct and delta18Op can be used for identifying phosphate sources to aquatic systems.

  15. Chemistry and isotopic composition of precipitation and surface waters in Khumbu valley (Nepal Himalaya): N dynamics of high elevation basins

    Energy Technology Data Exchange (ETDEWEB)

    Balestrini, Raffaella, E-mail: balestrini@irsa.cnr.it [Water Research Institute, National Research Council (IRSA-CNR), Via del Mulino 19, Brugherio, MB (Italy); Polesello, Stefano [Water Research Institute, National Research Council (IRSA-CNR), Via del Mulino 19, Brugherio, MB (Italy); Sacchi, Elisa [Department of Earth and Environmental Sciences, University of Pavia and IGG-CNR, Via Ferrata 1, 27100 Pavia (Italy)

    2014-07-01

    We monitored the chemical and isotopic compositions of wet depositions, at the Pyramid International Laboratory (5050 m a.s.l.), and surrounding surface waters, in the Khumbu basin, to understand precipitation chemistry and to obtain insights regarding ecosystem responses to atmospheric inputs. The major cations in the precipitation were NH{sub 4}{sup +} and Ca{sup 2+}, whereas the main anion was HCO{sub 3}{sup −}, which constituted approximately 69% of the anions, followed by NO{sub 3}{sup −}, SO{sub 4}{sup 2−} and Cl{sup −}. Data analysis suggested that Na{sup +}, Cl{sup −} and K{sup +} were derived from the long-range transport of marine aerosols. Ca{sup 2+}, Mg{sup 2+} and HCO{sub 3}{sup −} were related to rock and soil dust contributions and the NO{sub 3}{sup −} and SO{sub 4}{sup 2−} concentrations were derived from anthropogenic sources. Furthermore, NH{sub 4}{sup +} was derived from gaseous NH{sub 3} scavenging. The isotopic composition of weekly precipitation ranged from − 1.9 to − 23.2‰ in δ{sup 18}O, and from − 0.8 to − 174‰ in δ{sup 2}H, with depleted values characterizing the central part of the monsoon period. The chemical composition of the stream water was dominated by calcite and/or gypsum dissolution. However, the isotopic composition of the stream water did not fully reflect the composition of the monsoon precipitation, which suggested that other water sources contributed to the stream flow. Precipitation contents for all ions were the lowest ones among those measured in high elevation sites around the world. During the monsoon periods the depositions were not substantially influenced by anthropogenic inputs, while in pre- and post-monsoon seasons the Himalayas could not represent an effective barrier for airborne pollution. In the late monsoon phase, the increase of ionic contents in precipitation could also be due to a change in the moisture source. The calculated atmospheric N load (0.30 kg ha{sup −1} y{sup −1

  16. Variation in the isotopic composition of striped weakfish Cynoscion guatucupa of the Southwest Atlantic Ocean in response to dietary shifts

    Directory of Open Access Journals (Sweden)

    M. N. Paso Viola

    2017-08-01

    Full Text Available Abstract The aim of this study was to analyze the isotopic composition in muscle of striped weakfish Cynoscion guatucupa from Southwest Atlantic Ocean in order to evaluate a possible variation in δ13C and δ15N in response to dietary shifts that occur as animals grow. We also explored for isotopic evidence of differences between sample locations. The results showed an agreement between isotope analysis and previous conventional studies. Differences in the isotope composition between sampling location were not observed. A positive relation exists between isotope values and total body length of the animals. The Cluster analysis defined three groups of size classes, validated by the MDS. Differences in the relative consumption of prey species in each size class were also observed performing isotope mixing models (SIAR. Variation in δ15N among size classes would be associated with the consumption of a different type of prey as animals grow. Small striped weakfish feed on small crustaceans and progressively increase their consumption of fish (anchovy, Engraulis anchoita, increasing by this way their isotope values. On the other hand, differences in δ13C values seemed to be related to age-class specific spatial distribution patterns. Therefore, large and small striped weakfish remain specialized but feeding on different prey at different trophic levels. These results contribute to the study of the diet of striped weakfish, improve the isotopic ecology models and highlight on the importance of accounting for variation in the isotopic composition in response to dietary shifts with the size of one of the most important fishery resources in the region.

  17. Variation in the isotopic composition of striped weakfish Cynoscion guatucupa of the Southwest Atlantic Ocean in response to dietary shifts.

    Science.gov (United States)

    Viola, M N Paso; Riccialdelli, L; Jaureguizar, A; Panarello, H O; Cappozzo, H L

    2017-08-17

    The aim of this study was to analyze the isotopic composition in muscle of striped weakfish Cynoscion guatucupa from Southwest Atlantic Ocean in order to evaluate a possible variation in δ13C and δ15N in response to dietary shifts that occur as animals grow. We also explored for isotopic evidence of differences between sample locations. The results showed an agreement between isotope analysis and previous conventional studies. Differences in the isotope composition between sampling location were not observed. A positive relation exists between isotope values and total body length of the animals. The Cluster analysis defined three groups of size classes, validated by the MDS. Differences in the relative consumption of prey species in each size class were also observed performing isotope mixing models (SIAR). Variation in δ15N among size classes would be associated with the consumption of a different type of prey as animals grow. Small striped weakfish feed on small crustaceans and progressively increase their consumption of fish (anchovy, Engraulis anchoita), increasing by this way their isotope values. On the other hand, differences in δ13C values seemed to be related to age-class specific spatial distribution patterns. Therefore, large and small striped weakfish remain specialized but feeding on different prey at different trophic levels. These results contribute to the study of the diet of striped weakfish, improve the isotopic ecology models and highlight on the importance of accounting for variation in the isotopic composition in response to dietary shifts with the size of one of the most important fishery resources in the region.

  18. An overview of noble gas (He, Ne, Ar, Xe) contents and isotope signals in terrestrial diamond

    Science.gov (United States)

    Basu, S.; Jones, A. P.; Verchovsky, A. B.; Kelley, S. P.; Stuart, F. M.

    2013-11-01

    high 21Ne/22Ne and 131,134,136Xe/132Xe ratios. In many diamonds, variations in both concentration and isotopic composition within samples from the same geographical location require complex diamond growth. For example, coated stones of Zaire trap noble gases from multiple sources and different generations of diamond growth. Thus noble gas studies have the potential to record major processes during the complex growth histories of natural diamond and also to provide valuable information about the sub-continental mantle. Noble gas signatures may be affected by diffusive losses, notably in some framesites.

  19. Lena Trough MORB: Trace Element and Isotopic Composition of a Very Slow Spreading Ridge

    Science.gov (United States)

    Nauret, F.; Weis, D.; Snow, J. E.

    2005-12-01

    Extreme non-hotspot MORB compositions are less straightforward to explain than comparable OIB's, where all manner of enriched components may be derived from plume material. Here we report a new isotope and trace element study of dredged samples from the ultra-slow (7.5 mm/yr effective full-rate) Lena Trough rift in the Arctic Ocean and the western end of Gakkel Ridge (13mm/yr full rate). The few basalts found in Lena Trough are alkali-MORB with an extreme enrichment of incompatible trace elements, particularly alkalies and Ba (Ba/Th=350±50, Ba/Nb=17±1, Nb/U=69±, (La/Sm)PM=1.39±0.25) and by a garnet-source signature with (Dy/Yb)PM=1.22±0.06. The range of radiogenic isotopic ratios is 87Sr/86Sr=0.7036-0.7044, 143Nd/144Nd=0.51277-0.51230, 206Pb/204Pb=17.75-17.99, 207Pb/204Pb=15.41-15.44 and 208Pb/204Pb=37.54-37.79. In comparison, Western Gakkel Ridge MORB compositions are similar to N-MORB (Ba/Th=143±60, Ba/Nb=11±3, Nb/U=45±6, 87Sr/86Sr=0.7029-0.7030, 143Nd/144Nd=0.51307-0.51310, 206Pb/204Pb=17.97-18.08, 207Pb/204Pb=15.43-15.44, and 208Pb/204Pb=37.73-37.81). The Lena Trough high-precision MC-ICP-MS Pb data define linear Pb-Pb arrays extending to quite unradiogenic values. These arrays extend towards the more radiogenic values of some Gakkel MORBs, which show very limited variations on their own. Together with negative linear correlations between trace element ratios and Nd-Pb isotope systematics, we interpret these Pb linear arrays as reflecting mixing between a DMM component (similar to Gakkel Ridge MORB source) and a highly enriched component, with radiogenic Sr isotopes but low Nd and Pb isotopic ratios. The Lena Trough source contains residual garnet and is preferentially sampled by low degree partial melting. The source of the enriched component of the Lena Trough alkali MORB is interpreted to be olivine-free pyroxenite, taking into account the shallow pressure of partial melting, indicated by major elements. This is a clear indication of a "mantle vein

  20. Characterizing agricultural soil nitrous acid (HONO) and nitric oxide (NO) emissions with their nitrogen isotopic composition

    Science.gov (United States)

    Chai, J.; Miller, D. J.; Guo, F.; Dell, C. J.; Karsten, H.; Hastings, M. G.

    2017-12-01

    Nitrous acid (HONO) is a major source of atmospheric hydroxyl radical (OH), which greatly impacts air quality and climate. Fertilized soils may be important sources of HONO in addition to nitric oxide (NO). However, soil HONO emissions are especially challenging to quantify due to huge spatial and temporal variation as well as unknown HONO chemistry. With no in-situ measurements available, soil HONO emissions are highly uncertain. Isotopic analysis of HONO may provide a tool for tracking these sources. We characterize in situ soil HONO and NO fluxes and their nitrogen isotopic composition (δ15N) across manure management and meteorological conditions during a sustainable dairy cropping study in State College, Pennsylvania. HONO and NO were simultaneously collected at hourly resolution from a custom-coated dynamic soil flux chamber ( 3 LPM) using annular denuder system (ADS) coupled with an alkaline-permanganate NOx collection system for offline isotopic analysis of δ15N with ±0.6 ‰ (HONO) and ±1.5 ‰ (NO) precision. The ADS method was tested using laboratory generated HONO flowing through the chamber to verify near 100% collection (with no isotopic fractionation) and suitability for soil HONO collection. Corn-soybean rotation plots (rain-fed) were sampled following dairy manure application with no-till shallow-disk injection (112 kg N ha-1) and broadcast with tillage incorporation (129 kg N ha-1) during spring 2017. Soil HONO fluxes (n=10) ranged from 0.1-0.6 ng N-HONO m-2 s-1, 4-28% of total HONO+NO mass fluxes. HONO and NO fluxes were correlated, with both declining during the measurement period. The soil δ15N-HONO flux weighted mean ±1σ of -15 ± 6‰ was less negative than δ15N of simultaneously collected NO (-29 ± 8‰). This can potentially be explained by fractionations associated with microbial conversion of nitrite, abiotic production of HONO from soil nitrite, and uptake and release with changing soil moisture. Our results have implications for

  1. Isotopic composition of low-latitude paleoprecipitation during the Early Cretaceous

    Science.gov (United States)

    Suarez, M.B.; Gonzalez, Luis A.; Ludvigson, Greg A.; Vega, F.J.; Alvarado-Ortega, J.

    2009-01-01

    The response of the hydrologic cycle in global greenhouse conditions is important to our understanding of future climate change and to the calibration of global climate models. Past greenhouse conditions, such as those of the Cretaceous, can be used to provide empirical data with which to evaluate climate models. Recent empirical studies have utilized pedogenic carbonates to estimate the isotopic composition of meteoric waters and calculate precipitation rates for the AptianAlbian. These studies were limited to data from mid(35??N) to high (75??N) paleolatitudes, and thus future improvements in accuracy will require more estimates of meteoric water compositions from numerous localities around the globe. This study provides data for tropical latitudes (18.5??N paleolatitude) from the Tlayua Formation, Puebla, Mexico. In addition, the study confirms a shallow nearshore depositional environment for the Tlayua Formation. Petrographic observations of fenestral fabrics, gypsum crystal molds, stromatolitic structures, and pedogenic matrix birefringence fabric support the interpretation that the strata represent deposition in a tidal flat environment. Carbonate isotopic data from limestones of the Tlayua Formation provide evidence of early meteoric diagenesis in the form of meteoric calcite lines. These trends in ??18O versus ??13C were used to calculate the mean ??18O value of meteoric water, which is estimated at -5.46 ?? 0.56??? (Vienna Standard Mean Ocean Water [VSMOW]). Positive linear covariant trends in oxygen and carbon isotopic values from some horizons were used to estimate evaporative losses of vadose groundwater from tropical exposure surfaces during the Albian, and the resulting values range from 8% to 12%. However, the presence of evaporative mineral molds indicates more extensive evaporation. The added tropical data improve latitudinal coverage of paleoprecipitation ??18O estimates. The data presented here imply that earlier isotope mass balance models most

  2. Tetrathionate and Elemental Sulfur Shape the Isotope Composition of Sulfate in Acid Mine Drainage

    Directory of Open Access Journals (Sweden)

    Nurgul Balci

    2017-08-01

    Full Text Available Sulfur compounds in intermediate valence states, for example elemental sulfur, thiosulfate, and tetrathionate, are important players in the biogeochemical sulfur cycle. However, key understanding about the pathways of oxidation involving mixed-valance state sulfur species is still missing. Here we report the sulfur and oxygen isotope fractionation effects during the oxidation of tetrathionate (S4O62− and elemental sulfur (S° to sulfate in bacterial cultures in acidic conditions. Oxidation of tetrathionate by Acidithiobacillus thiooxidans produced thiosulfate, elemental sulfur and sulfate. Up to 34% of the tetrathionate consumed by the bacteria could not be accounted for in sulfate or other intermediate-valence state sulfur species over the experiments. The oxidation of tetrathionate yielded sulfate that was initially enriched in 34S (ε34SSO4−S4O6 by +7.9‰, followed by a decrease to +1.4‰ over the experiment duration, with an average ε34SSO4−S4O6 of +3.5 ± 0.2‰ after a month of incubation. We attribute this significant sulfur isotope fractionation to enzymatic disproportionation reactions occurring during tetrathionate decomposition, and to the incomplete transformation of tetrathionate into sulfate. The oxygen isotope composition of sulfate (δ18OSO4 from the tetrathionate oxidation experiments indicate that 62% of the oxygen in the formed sulfate was derived from water. The remaining 38% of the oxygen was either inherited from the supplied tetrathionate, or supplied from dissolved atmospheric oxygen (O2. During the oxidation of elemental sulfur, the product sulfate became depleted in 34S between −1.8 and 0‰ relative to the elemental sulfur with an average for ε34SSO4−S0 of −0.9 ± 0.2‰ and all the oxygen atoms in the sulfate derived from water with an average normal oxygen isotope fractionation (ε18OSO4−H2O of −4.4‰. The differences observed in δ18OSO4 and the sulfur isotope composition of sulfate (δ34SSO4

  3. Winter diets of immature green turtles (Chelonia mydas) on a northern feeding ground: integrating stomach contents and stable isotope analyses

    Science.gov (United States)

    Williams, Natalie C.; Bjorndal, Karen A.; Lamont, Margaret M.; Carthy, Raymond R.

    2015-01-01

    The foraging ecology and diet of the green turtle, Chelonia mydas, remain understudied, particularly in peripheral areas of its distribution. We assessed the diet of an aggregation of juvenile green turtles at the northern edge of its range during winter months using two approaches. Stomach content analyses provide a single time sample, and stable isotope analyses integrate diet over a several-month period. We evaluated diet consistency in prey choice over time by comparing the results of these two approaches. We examined stomach contents from 43 juvenile green turtles that died during cold stunning events in St. Joseph Bay, Florida, in 2008 and 2011. Stomach contents were evaluated for volume, dry mass, percent frequency of occurrence, and index of relative importance of individual diet items. Juvenile green turtles were omnivorous, feeding primarily on seagrasses and tunicates. Diet characterizations from stomach contents differed from those based on stable isotope analyses, indicating the turtles are not feeding consistently during winter months. Evaluation of diets during warm months is needed.

  4. Neodymium isotopic variations in seawater

    Science.gov (United States)

    Piepgras, D. J.; Wasserburg, G. J.

    1980-01-01

    Direct measurement of the isotopic composition of Nd in the Atlantic agree with the Nd content in ferromanganese sediments and differ from the observed amounts in the Pacific samples. These data indicate the existence of distinctive differences in the isotopic composition of Nd in the waters of major oceans; the average values determined from seawater and ferromanganese sediments are considerably lower than in sources with oceanic mantle affinities showing that the REE in the oceans is dominated by continental sources. The Nd isotopic variations in seawater are applied to relate the residence time of Nd and mixing rates between the oceans.

  5. Distribution of uranium, thorium, and isotopic composition of uranium in soil samples of south Serbia: Evidence of depleted uranium

    OpenAIRE

    Sahoo Sarata Kumar; Fujimoto Kenzo; Čeliković Igor; Ujić Predrag; Žunić Zora S.

    2004-01-01

    Inductively coupled plasma mass spectrometry and thermal ionization mass spectrom - etry were used to measure concentration of uranium and thorium as well as isotopic composition of uranium respectively in soil samples collected around south Serbia. An analytical method was established for a routine sample preparation procedure for uranium and thorium. Uranium was chemically separated and purified from soil samples by anion exchange resin and UTEVA extraction chromatography and its isotopic c...

  6. Climate in the Great Lakes Region between 14,000 and 4000 years ago from isotopic composition of conifer wood

    Science.gov (United States)

    Steven W. Leavitt; Irina P. Panyushkina; Todd Lange; Alex Wiedenhoeft; Li Cheng; R. Douglas Hunter; John Hughes; Frank Pranschke; Allan F. Schneider; Joseph Moran; Ron Stieglitz

    2006-01-01

    The isotopic composition of ancient wood has the potential to provide information about past environments. We analyzed the ä13C, ä18O, and ä2H of cellulose of conifer trees from several cross-sections at each of 9 sites around the Great Lakes region ranging from ~4000 to 14,000 cal BP. Isotopic values of Picea, Pinus, and Thuja species seem inter-changeable for ä18O...

  7. In situ oxygen isotope compositions in olivines of different types of cosmic spherules: An assessment of relationships to chondritic particles

    Digital Repository Service at National Institute of Oceanography (India)

    Rudraswami, N.G.; ShyamPrasad, M.; Jones, R.H.; Nagashima, K.

    et al., 2015a). The micrometeorites that have entered Earth’s atmosphere at high zenith angle and low velocity are interesting because their petrologic and isotopic characteristics are largely preserved thereby providing constraints on the parent... et al., 2012). Oxygen isotope studies complemented by mineralogical compositions are vital to unravel the complexity involved in distinguishing the known components of micrometeorites and their parent bodies. For carbonaceous chondrites...

  8. Assessing the dietary sources of two cichlid species in River Nile sub-branches: Stomach contents, fatty acids and stable isotopes analyses

    OpenAIRE

    Abd El-Karim, Mohamad S.; Ali, Mohamad H.H.; Mahmoud, Abeer M.A.

    2016-01-01

    We assess the importance of four different food sources as dietary components of Oreochromis niloticus and Sarotherodon galilaeus in Nile sub-branches using stomach contents, fatty acids (FA) and stable isotopes (SI) analyses. Diatoms were the dominant food items, whereas sand and mud constitute a major part of the stomach contents of both cichlids in the northern ElBehery canal. FAs and SI were compared in cichlids and four potential food sources. Carbon isotopes excluded the fresh macrophyt...

  9. Formation of Pt-bearing Western Pana pluton on the Kola Peninsula: Fluid regime as deduced from helium and argon isotopic compositions

    Science.gov (United States)

    Nivin, V. A.; Rundqvist, T. V.

    2017-01-01

    The distribution of He and Ar isotopes has been studied in 41 rock samples and seven monomineralic fractions from ore-bearing layered units and poorly differentiated host gabbronorite of the Western Pana mafic-ultramafic pluton on the Kola Peninsula. The gases assigned for mass-spectrometric analysis were released by means of whole-rock sample melting and by comminution mainly from fluid microinclusions. The data show that the present-day isotopic composition of noble gases in rocks from the pluton is caused by many factors: the degree of melt degassing, various concentrations and retention of the trapped isotopes, the contents of radioactive elements, and the generation and loss of radiogenic gases. The hypabyssal conditions of pluton formation facilitate the loss of primary mantle-derived volatile components and the dilution of magmatic fluid with near-surface paleometeoric waters containing air dissolved therein. The correlation of noble gas isotopes and ore-forming chemical elements does not suggest derivation of the latter from crustal material and evidences their mantle origin. Variations in the geochemical indices of the gas corroborate previously established or proposed multistage formation of the pluton, mainly, the autometamorphic character of postmagmatic processes and the participation of fluids in ore formation.

  10. Cenozoic climate evolution in Asian region and its influence on isotopic composition of precipitation

    Science.gov (United States)

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

    2015-04-01

    The evolution of Asian climate during the Cenozoic as well as the onset of monsoon systems in this area is highly debated. Factors that control climate include the geographical position of continents, the land-sea distribution and altitude of orogens. In tern, several climatic parameters such as air temperature, precipitation amount and isotopic fractionation through mass-dependent processes impact precipitation δ18O lapse rate. Stable oxygen paleoaltimetry is considered to be a very efficient and widely applied technique, but the link between stable oxygen composition of precipitation and climate is not well established. To quantify the influence of paleogeography changes on climate and precipitation δ18O over Asia, the atmospheric general circulation model LMDZ-iso, with embedded stable oxygen isotopes, was used. For more realistic experiments, sea surface temperatures were calculated with the fully coupled model FOAM. Various scenarios of TP growth have been applied together with Paleocene, Eocene, Oligocene and Miocene boundary conditions. The results of our numerical modelling show a significant influence of paleogeography changes on the Asian climate. The retreat of the Paratethys ocean, the changes in latitudinal position of India, and the height of the Tibetan Plateau most likely control precipitation patterns over Asia and cause spatial and temporal isotopic variations linked with the amount effect. Indian Ocean currents restructuring during the Eocene induces a substantial warming over Asian continent. The adiabatic and non-adiabatic temperature effects explain some of δ18O signal variations. We highlight the importance of these multiple factor on paleoelevations estimates derived using oxygen stable isotopes.

  11. Stable isotope composition of bulk and secondary carbonates from the Quaternary loess-paleosol sequence in Sutto, Hungary

    DEFF Research Database (Denmark)

    Koeniger, Paul; Barta, Gabriella; Thiel, Christine

    2014-01-01

    , and microscale secondary (authigenic) carbonates (calcified root cells, carbonate coatings, hypocoatings, and earthworm biospheroids) and concretions at 10 cm resolution were analysed to interpret stable isotope variations. Isotope values of bulk samples were in the range of 2.6 parts per thousand to -13.9 parts......, secondary carbonates showed more depleted values than bulk samples. Calcified root cells have the most depleted isotope composition with mean values of -16.0 parts per thousand and -11.8 parts per thousand for delta C-13 and 8180, respectively. Results indicate that loess and paleosol secondary carbonates...

  12. MEASUREMENT OF THE ISOTOPIC COMPOSITION OF HYDROGEN AND HELIUM NUCLEI IN COSMIC RAYS WITH THE PAMELA EXPERIMENT

    Energy Technology Data Exchange (ETDEWEB)

    Adriani, O.; Bongi, M. [Department of Physics, University of Florence, I-50019 Sesto Fiorentino, Florence (Italy); Barbarino, G. C. [Department of Physics, University of Naples ' ' Federico II' ' , I-80126 Naples (Italy); Bazilevskaya, G. A. [Lebedev Physical Institute, RU-119991, Moscow (Russian Federation); Bellotti, R.; Bruno, A. [Department of Physics, University of Bari, I-70126 Bari (Italy); Boezio, M.; Bonvicini, V.; Carbone, R. [INFN, Sezione di Trieste, I-34149 Trieste (Italy); Bogomolov, E. A. [Ioffe Physical Technical Institute, RU-194021 St. Petersburg (Russian Federation); Borisov, S.; Casolino, M.; De Pascale, M. P. [INFN, Sezione di Rome ' ' Tor Vergata' ' , I-00133 Rome (Italy); Bottai, S. [INFN, Sezione di Florence, I-50019 Sesto Fiorentino, Florence (Italy); Cafagna, F. [INFN, Sezione di Bari, I-70126 Bari (Italy); Campana, D. [INFN, Sezione di Naples, I-80126 Naples (Italy); Carlson, P. [KTH, Department of Physics, and the Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, SE-10691 Stockholm (Sweden); Castellini, G. [IFAC, I-50019 Sesto Fiorentino, Florence (Italy); Danilchenko, I. A. [National Research Nuclear University MEPhI, RU-115409 Moscow (Russian Federation); De Santis, C. [Department of Physics, University of Rome ' ' Tor Vergata' ' , I-00133 Rome (Italy); and others

    2013-06-10

    The satellite-borne experiment PAMELA has been used to make new measurements of cosmic ray H and He isotopes. The isotopic composition was measured between 100 and 600 MeV/n for hydrogen and between 100 and 900 MeV/n for helium isotopes over the 23rd solar minimum from 2006 July to 2007 December. The energy spectrum of these components carries fundamental information regarding the propagation of cosmic rays in the galaxy which are competitive with those obtained from other secondary to primary measurements such as B/C.

  13. Chemical and isotopic composition of secondary organic aerosol generated by α-pinene ozonolysis

    Science.gov (United States)

    Meusinger, Carl; Dusek, Ulrike; King, Stephanie M.; Holzinger, Rupert; Rosenørn, Thomas; Sperlich, Peter; Julien, Maxime; Remaud, Gerald S.; Bilde, Merete; Röckmann, Thomas; Johnson, Matthew S.

    2017-05-01

    Secondary organic aerosol (SOA) plays a central role in air pollution and climate. However, the description of the sources and mechanisms leading to SOA is elusive despite decades of research. While stable isotope analysis is increasingly used to constrain sources of ambient aerosol, in many cases it is difficult to apply because neither the isotopic composition of aerosol precursors nor the fractionation of aerosol forming processes is well characterised. In this paper, SOA formation from ozonolysis of α-pinene - an important precursor and perhaps the best-known model system used in laboratory studies - was investigated using position-dependent and average determinations of 13C in α-pinene and advanced analysis of reaction products using thermal-desorption proton-transfer-reaction mass spectrometry (PTR-MS). The total carbon (TC) isotopic composition δ13C of the initial α-pinene was measured, and the δ13C of the specific carbon atom sites was determined using position-specific isotope analysis (PSIA). The PSIA analysis showed variations at individual positions from -6.9 to +10. 5 ‰ relative to the bulk composition. SOA was formed from α-pinene and ozone in a constant-flow chamber under dark, dry, and low-NOx conditions, with OH scavengers and in the absence of seed particles. The excess of ozone and long residence time in the flow chamber ensured that virtually all α-pinene had reacted. Product SOA was collected on two sequential quartz filters. The filters were analysed offline by heating them stepwise from 100 to 400 °C to desorb organic compounds that were (i) detected using PTR-MS for chemical analysis and to determine the O : C ratio, and (ii) converted to CO2 for 13C analysis. More than 400 ions in the mass range 39-800 Da were detected from the desorbed material and quantified using a PTR-MS. The largest amount desorbed at 150 °C. The O : C ratio of material from the front filter increased from 0.18 to 0.25 as the desorption temperature was

  14. Sr and Nd isotopic and trace element compositions of Quaternary volcanic centers of the Southern Andes

    Science.gov (United States)

    Futa, K.; Stern, C.R.

    1988-01-01

    Isotopic compositions of samples from six Quaternary volcanoes located in the northern and southern extremities of the Southern Volcanic Zone (SVZ, 33-46??S) of the Andes and from four centers in the Austral Volcanic Zone (AVZ, 49-54??S) range for 87Sr 86Sr from 0.70280 to 0.70591 and for 143Nd 144Nd from 0.51314 to 0.51255. The ranges are significantly greater than previously reported from the southern Andes but are different from the isotopic compositions of volcanoes in the central and northern Andes. Basalts and basaltic andesites from three centers just north of the Chile Rise-Trench triple junction have 87Sr 86Sr, 143Nd 144Nd, La Yb, Ba La, and Hf Lu that lie within the relatively restricted ranges of the basic magmas erupted from the volcanic centers as far north as 35??S in the SVZ of the Andes. The trace element and Sr and Nd isotopic characteristics of these magmas may be explained by source region contamination of subarc asthenosphere, with contaminants derived from subducted pelagic sediments and seawater-altered basalts by dehydration of subducted oceanic lithosphere. In the northern extremity of the SVZ between 33?? and 34??S, basaltic andesites and andesites have higher 87Sr 86Sr, Rb Cs, and Hf Lu, and lower 143Nd 144Nd than basalts and basaltic andesites erupted farther south in the SVZ, which suggests involvement of components derived from the continental crust. In the AVZ, the most primitive sample, high-Mg andesite from the southernmost volcanic center in the Andes (54??S) has Sr and Nd isotopic compositions and K Rb and Ba La similar to MORB. The high La Yb of this sample suggests formation by small degrees of partial melting of subducted MORB with garnet as a residue. Samples from centers farther north in the AVZ show a regionally regular northward increase in SiO2, K2O, Rb, Ba, Ba La, and 87Sr 86Sr and decrease in MgO, Sr, K Rb, Rb Cs, and 143Nd 144Nd, suggesting increasingly greater degrees of fractional crystallization and associated intra

  15. Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography

    Directory of Open Access Journals (Sweden)

    F. Fripiat

    2012-07-01

    Full Text Available Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO2 variation. In this context, the natural silicon isotopic composition30Si of sedimentary biogenic silica has been used to reconstruct past Si-consumption:supply ratios in the surface waters. We present a new dataset in the Southern Ocean from a IPY-GEOTRACES transect (Bonus-GoodHope which includes for the first time summer δ30Si signatures of suspended biogenic silica (i for the whole water column at three stations and (ii in the mixed layer at seven stations from the subtropical zone up to the Weddell Gyre. In general, the isotopic composition of biogenic opal exported to depth was comparable to the opal leaving the mixed layer and did not seem to be affected by any diagenetic processes during settling, even if an effect of biogenic silica dissolution cannot be ruled out in the northern part of the Weddell Gyre. We develop a mechanistic understanding of the processes involved in the modern Si-isotopic balance, by implementing a mixed layer model. We observe that the accumulated biogenic silica (sensu Rayleigh distillation should satisfactorily describe the δ30Si composition of biogenic silica exported out of the mixed layer, within the limit of the current analytical precision on the δ30Si. The failures of previous models (Rayleigh and steady state become apparent especially at the end of the productive period in the mixed layer, when biogenic silica production and export are low. This results from (1 a higher biogenic silica dissolution:production ratio imposing a lower net fractionation factor and (2 a higher Si-supply:Si-uptake ratio supplying light Si-isotopes into the mixed layer. The latter effect is especially expressed when the summer mixed layer becomes strongly Si-depleted, together with a large

  16. Isotopic composition of precipitations in Brazil: isothermic models and the influence of evapotranspiration in the Amazonic Basin

    International Nuclear Information System (INIS)

    Dall'Olio, Attilio.

    1976-11-01

    The simplest theoretical models of the isotopic fractionation of water during equilibrium isothermical processes are analized in detail. The theoretical results are applied to the interpretation of the stable isotope concentrations in the precipitations of 11 Brazilian cities that belong to the international network of IAEA/WMO. The analysis shows that the experimental data are fairly consistent with such equilibrium models; no non-equilibrium processes need to be assumed. The study of the stable isotope content of precipitations in the Amazonic Basin suggests some modifications to the models in order that the evapotranspiration contribution to the vapour balance be taken into account [pt

  17. Hydrogeological investigations in the Harwell region: the use of environmental isotopes, inert gas contents, and the uranium decay series

    International Nuclear Information System (INIS)

    Alexander, J.; Andrews, J.N.

    1984-12-01

    A comprehensive range of environmental isotopes, radioelement and dissolved gas contents have been measured in groundwaters from the high permeability formations of the Harwell area. These analyses were undertaken as part of a hydrochemical validation of groundwater circulation patterns derived from potentiometric data. These investigations have focused upon the Corallian and Great Oolite formations since these sandwich the Oxford Clay. Geochemical, isotopic, radioelement and inert gas studies have demonstrated consistent trends which substantiate fluid migration patterns derived from hydraulic considerations. Groundwaters at downdip localities in both the Corallian and Great Oolite formations are the oldest waters sampled from the region. Variations in trends in parameters can be attributed to cross-formational flow and subsequent mixing of groundwaters. Individually these techniques can only provide limited information, but the combination of methods used have provided corroborative evidence concerning the direction of fluid circulation in the Harwell region. (author)

  18. Modeling the Nd isotopic composition in the North Atlantic basin using an eddy-permitting model

    Directory of Open Access Journals (Sweden)

    T. Arsouze

    2010-09-01

    Full Text Available Boundary Exchange (BE – exchange of elements between continental margins and the open ocean has been emphasized as a key process in the oceanic cycle of neodymium (Nd (Lacan and Jeandel, 2005a. Here, we use a regional eddy-permitting resolution Ocean General Circulation Model (1/4° of the North Atlantic basin to simulate the distribution of the Nd isotopic composition, considering BE as the only source. Results show good agreement with the data, confirming previous results obtained using the same parameterization of the source in a coarse resolution global model (Arsouze et al., 2007, and therefore the major control played by the BE processes in the Nd cycle on the regional scale. We quantified the exchange rate of the BE, and found that the time needed for the continental margins to significantly imprint the chemical composition of the surrounding seawater (further referred as characteristic exchange time is of the order of 0.2 years. However, the timescale of the BE may be subject to large variations as a very short exchange time (a few days is needed to reproduce the highly negative values of surface waters in the Labrador Sea, whereas a longer one (up to 0.5 years is required to simulate the radiogenic influence of basaltic margins and distinguish the negative isotopic signatures of North Atlantic Deep Water from the more radiogenic southern origin water masses. This likely represents geographical variations in erosion fluxes and the subsequent particle load onto the continental margins. Although the parameterization of the BE is the same in both configurations of the model, the characteristic exchange time in the eddy-permitting configuration is significantly lower than the previous evaluations using a low resolution configuration (6 months to 10 years, but however in agreement with the available seawater Nd isotope data. This results highlights the importance of the model dynamics in simulating the BE process.

  19. Influence of chemical reactivities of lipids bound in different pools on their isotopic compositions during degradation in marine sediments

    Science.gov (United States)

    Sun, M.; Pan, H.; Culp, R.

    2013-05-01

    Lipid biomarkers and associated compound specific stable carbon isotope compositions have been widely applied to study biogeochemical cycling of organic matter in natural environments. This experimental study was specifically designed to examine the influence of chemical reactivities of lipid compounds bound in different pools on their isotopic composition during microbial degradation in marine sediments. 13C-labeled (labeling at different carbon positions of fatty acid chains) and unlabeled tripalmitins were spiked and incubated in natural oxic (top 1 cm) and anoxic (> 10 cm) marine sediments. In anoxic sediments, neither naturally-occurred fatty acids nor tripalmitin-derived 16:0 fatty acid were apparently degraded within two months and hence no significant variation in stable carbon isotopic composition of 16:0 fatty acid was observed. However, in oxic sediments, both naturally-occurred fatty acids and spiked tripalmitin-derived 16:0 fatty acid were degraded by 26% - 95% during incubation. For natural fatty acids such as 14:0, 16:1, 18:1, 20:5/20:4, and >C20:0, degradation rates varied according to the following order: polyunsaturated > monounsaturated > short chain saturated > long chain saturated fatty acids, which reflects variable reactivities of natural lipid compounds from different sources. Tripalmitin-derived 16:0 fatty acid degraded at an at least 2-3× faster rate compared to naturally-occurred 16:0 in sediments. Meanwhile, isotopic compositions of 16:0 fatty acid in the oxic sediments shifted negatively during incubation. It appears that the isotopic shifts are dependent on the amount of 13C-labeled compound spiked into the sediments but not related to the labeling position of 13C in the molecular structure. The results from this study provide direct evidence that the relative reactivities of lipid compounds from different sources (or different pools) can cause alterations in molecular isotopic composition during microbial degradation in natural

  20. Unsaturated zone carbon dioxide flux, mixing, and isotopic composition at the USGS Amargosa Desert Research Site

    Science.gov (United States)

    Conaway, C. H.; Thordsen, J. J.; Thomas, B.; Haase, K.; Moreo, M. T.; Walvoord, M. A.; Andraski, B. J.; Stonestrom, D. A.

    2015-12-01

    Elevated concentrations of tritium, radiocarbon, and volatile organic compounds at the USGS Amargosa Desert Research Site, adjacent to a low-level radioactive waste disposal facility, have stimulated research on factors affecting transport of these contaminants. This research includes an examination of unsaturated zone carbon dioxide (CO2) fluxes, mixing, and isotopic composition, which can help in understanding these factors. In late April 2015 we collected 76 soil-gas samples in multi-layer foil bags from existing 1.5-m deep tubes, both inside and outside the low-level waste area, as well as from two 110-m-deep multilevel gas-sampling boreholes and a distant background site. These samples were analyzed for carbon dioxide concentration and isotopic composition by direct injection into a cavity ring-down spectrometer. Graphical analysis of results indicates mixing of CO2 characteristic of the root zone (δ13C -18 ‰ VPDB), deep soil gas of the capillary fringe (-20‰), and CO2 produced by microbial respiration of organic matter disposed in the waste area trenches (-28‰). Land-surface boundary conditions are being constrained by the application of a novel non-dispersive infrared sensor and traditional concentration and flux measurements, including discrete CO2 flux data using a gas chamber method to complement continuous data from surface- and tower-based CO2 sensors. These results shed light on radionuclide and VOC mobilization and transport mechanisms from this and similar waste disposal facilities.

  1. Mechanisms controlling the carbon stable isotope composition of phytoplankton in karst reservoirs

    Directory of Open Access Journals (Sweden)

    Baoli Wang

    2013-02-01

    Full Text Available In order to systematically understand the mechanisms controlling the carbon stable isotope composition of phytoplankton (δ13CPHYin freshwater ecosystems, seasonal changes in δ13CPHY and related environmental factors were determined in karst reservoirs from the Wujiang river basin, China. Substantial and systematic differences within seasons and reservoirs were observed for δ13CPHY, which ranged from -39.2‰ to -15.1‰. An increase in water temperature triggered fast growth of phytoplankton which assimilated more dissolved inorganic carbon (DIC, resulting in the increase of δ13CPHY, δ13CDIC and pH. When the concentration of dissolved carbon dioxide (CO2 was less than 10 mmol L–1, phytoplankton shifted to using HCO3– as a carbon source. This resulted in the sharp increase of δ13CPHY. The carbon stable isotope composition of phytoplankton tended to decrease with the increase of Bacillariophyta, which dominated in January and April, but tended to increase with the increase of Chlorophyta and Dinophyta, which dominated in July. Multiple regression equations suggested that the influence of biological factors such as taxonomic difference on δ13CPHY could be equal or more important than that of physical and chemical factors. Thus, the effect of taxonomic differences on δ13CPHY must be considered when explaining the δ13C of organic matter in lacustrine ecosystem.

  2. Impact of metabolism and growth phase on the hydrogen isotopic composition of microbial fatty acids

    Science.gov (United States)

    Heinzelmann, Sandra M.; Villanueva, Laura; Sinke-Schoen, Danielle; Sinninghe Damsté, Jaap S.; Schouten, Stefan; van der Meer, Marcel T. J.

    2015-01-01

    Microorganisms are involved in all elemental cycles and therefore it is important to study their metabolism in the natural environment. A recent technique to investigate this is the hydrogen isotopic composition of microbial fatty acids, i.e., heterotrophic microorganisms produce fatty acids enriched in deuterium (D) while photoautotrophic and chemoautotrophic microorganisms produce fatty acids depleted in D compared to the water in the culture medium (growth water). However, the impact of factors other than metabolism have not been investigated. Here, we evaluate the impact of growth phase compared to metabolism on the hydrogen isotopic composition of fatty acids of different environmentally relevant microorganisms with heterotrophic, photoautotrophic and chemoautotrophic metabolisms. Fatty acids produced by heterotrophs are enriched in D compared to growth water with εlipid/water between 82 and 359‰ when grown on glucose or acetate, respectively. Photoautotrophs (εlipid/water between −149 and −264‰) and chemoautotrophs (εlipid/water between −217 and −275‰) produce fatty acids depleted in D. Fatty acids become, in general, enriched by between 4 and 46‰ with growth phase which is minor compared to the influence of metabolisms. Therefore, the D/H ratio of fatty acids is a promising tool to investigate community metabolisms in nature. PMID:26005437

  3. Late quaternary history and uranium isotopic compositions of ground water discharge deposits, Crater Flat, Nevada

    International Nuclear Information System (INIS)

    Paces, J.B.; Taylor, E.M.; Bush, C.

    1993-01-01

    Three carbonate-rich spring deposits are present near the southern end of Crater Flat, NV, approximately 18 km southwest of the potential high-level waste repository at Yucca Mountain. We have analyzed five samples of carbonate-rich material from two of the deposits for U and Th isotopic compositions. Resulting U-series disequilibrium ages indicate that springs were active at 18 ± 1, 30 ± 3, 45 ± 4 and >70 ka. These ages are consistent with a crude internal stratigraphy at one site. Identical ages for two samples at two separate sites suggest that springs were contemporaneous, at least in part, and were most likely part of the same hydrodynamic system. In addition, initial U isotopic compositions range from 2.8 to 3.8 and strongly suggest that ground water from the regional Tertiary-volcanic aquifer provided the source for these hydrogenic deposits. This interpretation, along with water level data from near-by wells suggest that the water table rose approximately 80 to 115 m above present levels during the late Quaternary and may have fluctuated repeatedly. Current data are insufficient to allow reconstruction of a detailed depositional history, however geochronological data are in a good agreement with other paleoclimatic proxy records preserved throughout the region. Since these deposits are down gradient from the potential repository site, the possibility of higher ground water levels in the future dramatically shortens both vertical and lateral ground water pathways and reduces travel times of transported radionuclides to potential discharge sites

  4. A revision in hydrogen isotopic composition of USGS42 and USGS43 human-hair stable isotopic reference materials for forensic science

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping

    2016-01-01

    The hydrogen isotopic composition (δ2HVSMOW-SLAP) of USGS42 and USGS43 human hair stable isotopic reference materials, normalized to the VSMOW (Vienna-Standard Mean Ocean Water)–SLAP (Standard Light Antarctic Precipitation) scale, was originally determined with a high temperature conversion technique using an elemental analyzer (TC/EA) with a glassy carbon tube and glassy carbon filling and analysis by isotope-ratio mass spectrometer (IRMS). However, the TC/EA IRMS method can produce inaccurate δ2HVSMOW-SLAPresults when analyzing nitrogen-bearing organic substances owing to the formation of hydrogen cyanide (HCN), leading to non-quantitative conversion of a sample into molecular hydrogen (H2) for IRMS analysis. A single-oven, chromium-filled, elemental analyzer (Cr-EA) coupled to an IRMS substantially improves the measurement quality and reliability of hydrogen isotopic analysis of hydrogen- and nitrogen-bearing organic material because hot chromium scavenges all reactive elements except hydrogen. USGS42 and USGS43 human hair isotopic reference materials have been analyzed with the Cr-EA IRMS method, and the δ2HVSMOW-SLAP values of their non-exchangeable hydrogen fractions have been revised:where mUr = 0.001 = ‰. On average, these revised δ2HVSMOW-SLAP values are 5.7 mUr more positive than those previously measured. It is critical that readers pay attention to the δ2HVSMOW-SLAP of isotopic reference materials in publications as they may need to adjust the δ2HVSMOW–SLAP measurement results of human hair in previous publications to ensure all results are on the same isotope-delta scale.

  5. Chemotaxonomic significance of distribution and stable carbon isotopic composition of long-chain alkanes and alkan-1-ols in C{sub 4} grass waxes

    Energy Technology Data Exchange (ETDEWEB)

    Rommerskirchen, F.; Plader, A. [Carl von Ossietzky University, Oldenburg (Germany). Institute of Chemistry and Biology of the Marine Environment; Eglinton, G. [Hanse Institute for Advanced Study, Delmenhorst (Germany); Chikaraishii, Yoshito [Japan Agency for Marine-Earth Science and Technology, Yokosuka (Japan). Institute for Research on Earth Evolution

    2006-10-15

    Grasses (Poaceae) are distributed across the world in broad latitudinal belts and are an important source of C4 biomass in the geological record of soils as well as lake and marine sediments. We examined long-chain leaf wax components of thirty-five C{sub 4} grasses of the subfamilies Aristidoideae, Chloridoideae and Panicoideae from the southern African grasslands and savannas and three C{sub 3} grasses of the subfamily Pooideae from Peru and Australia and review the relevant botanical, phytogeographic and leaf wax compositional background information. Contents, distribution patterns and molecular stable carbon isotopic compositions of long-chain n-alkanes (n-C{sub 27} to n-C{sub 35}) and n-alkan-1-ols (n-C{sub 22} to n-C{sub 32}) were used to estimate the chemotaxonomic relevance of wax signatures of whole plants, separately for different subfamilies and for members of the three C{sub 4} subtypes (NADP-ME, NAD-ME and PCK). Two grass species were separated into flower heads, leaves and stems and the parts analysed separately. Grass flowers contain remarkable amounts of short-chain n-alkanes, which may have a significant influence on the chemical signature of the whole plant, whereas n-alkanol distribution patterns exhibit no systematics. The stable carbon isotopic composition of both biomarker types in different plant parts is remarkably uniform. Chemotaxonomic differentiation was not possible on a species level based on whole plant samples, but was more successful for averages of subfamily and photosynthetic subtype data. Wax signatures of C{sub 4} grasses are generally distinguishable from those of C{sub 3} species by heavier isotopic values, higher contents of n-C{sub 31} and n-C{sub 33} alkanes and the abundance of the n-C{sub 32} n-alkanol, which is largely absent in C{sub 3} grass waxes. Especially the waxes of the NAD-ME and PCK C{sub 4}-subtype grasses, which thrive in extremely arid tropical and subtropical areas, contain high relative amounts of longer

  6. Evaluating the Historical Importance of Impact Induced Hydrothermal Systems on Mars Using the Stable Isotopic Composition of Martian Water

    Science.gov (United States)

    Niles, Paul B.

    2010-01-01

    The importance of impact events during the early history of Mars is obvious through a simple examination of the character of the martian surface. This ancient, heavily cratered terrain has been shown to be associated with extensive phyllosilicate deposits. This geologic link could suggest that the extensive phyllosilicate-forming alteration may have occurred during early martian history through impact-induced hydrothermal alteration. However, examination of the oxygen isotopic composition of water on Mars suggests that the extensive phyllosilicate deposits were formed primarily through low temperature (The average oxygen isotopic composition of water on Earth is dictated by the nature of water-rock interactions. If these interactions occur at higher temperatures then the water will contain a higher proportion of 18O, while lower temperature interactions will result in water with a lower proportion of 18O. Water on Earth today contains a higher proportion of 18O because of plate tectonics and hydrothermal interaction at mid-ocean ridges. The oxygen isotopic composition of water on early earth, however, may have been quite different, containing a smaller proportion of 18O suggesting much less hydrothermal interaction. Because there are not yet any direct measurements of the oxygen isotopic composition of water on Mars, it needs to be inferred through examination of carbonates preserved in martian meteorites and the isotopic composition of atmospheric CO2. This can be done because the oxygen incorporated into carbonates and CO2 is easily exchanged with liquid water if it is present. Independently, both measurements provide an estimate for the (Sigma)18O of water on Mars to be near -16%. This composition is consistent with low temperature weathering of the silicate crust, and indicates that impact hydrothermal systems did not play an important role in the early alteration of the planet. However, our understanding of impact-induced hydrothermal systems remains unclear

  7. Ginseng authenticity testing by measuring carbon, nitrogen, and sulfur stable isotope compositions that differ based on cultivation land and organic fertilizer type.

    Science.gov (United States)

    Chung, Ill-Min; Lee, Taek-Jun; Oh, Yong-Taek; Ghimire, Bimal Kumar; Jang, In-Bae; Kim, Seung-Hyun

    2017-04-01

    The natural ratios of carbon (C), nitrogen (N), and sulfur (S) stable isotopes can be varied in some specific living organisms owing to various isotopic fractionation processes in nature. Therefore, the analysis of C, N, and S stable isotope ratios in ginseng can provide a feasible method for determining ginseng authenticity depending on the cultivation land and type of fertilizer. C, N, and S stable isotope composition in 6-yr-old ginseng roots (Jagyeongjong variety) was measured by isotope ratio mass spectrometry. The type of cultivation land and organic fertilizers affected the C, N, and S stable isotope ratio in ginseng ( p  authenticity depending on cultivation conditions.

  8. Sources of variability and comparability between salmonid stomach contents and isotopic analyses: study design lessons and recommendations

    Science.gov (United States)

    Vinson, M.R.; Budy, P.

    2011-01-01

    We compared sources of variability and cost in paired stomach content and stable isotope samples from three salmonid species collected in September 2001–2005 and describe the relative information provided by each method in terms of measuring diet overlap and food web study design. Based on diet analyses, diet overlap among brown trout, rainbow trout, and mountain whitefish was high, and we observed little variation in diets among years. In contrast, for sample sizes n ≥ 25, 95% confidence interval (CI) around mean δ15Ν and δ13C for the three target species did not overlap, and species, year, and fish size effects were significantly different, implying that these species likely consumed similar prey but in different proportions. Stable isotope processing costs were US$12 per sample, while stomach content analysis costs averaged US$25.49 ± $2.91 (95% CI) and ranged from US$1.50 for an empty stomach to US$291.50 for a sample with 2330 items. Precision in both δ15Ν and δ13C and mean diet overlap values based on stomach contents increased considerably up to a sample size of n = 10 and plateaued around n = 25, with little further increase in precision.

  9. Potassium Stable Isotopic Compositions Measured by High-Resolution MC-ICP-MS

    Science.gov (United States)

    Morgan, Leah E.; Lloyd, Nicholas S.; Ellam, Robert M.; Simon, Justin I.

    2012-01-01

    Potassium isotopic (K-41/K-39) compositions are notoriously difficult to measure. TIMS measurements are hindered by variable fractionation patterns throughout individual runs and too few isotopes to apply an internal spike method for instrumental mass fractionation corrections. Internal fractionation corrections via the K-40/K-39 ratio can provide precise values but assume identical K-40/K-39 ratios (e.g. 0.05% (1sigma) in [1]); this is appropriate in some cases (e.g. identifying excess K-41) but not others (e.g., determining mass fractionation effects and metrologically traceable isotopic abundances). SIMS analyses have yielded measurements with 0.25% precisions (1sigma) [2]. ICP-MS analyses are significantly affected by interferences from molecular species such as Ar-38H(+) and Ar-40H(+) and instrument mass bias. Single collector ICP-MS instruments in "cold plasma" mode have yielded uncertainties as low as 2% (1sigma, e.g. [3]). Although these precisions may be acceptable for some concentration determinations, they do not resolve isotopic variation in terrestrial materials. Here we present data from a series of measurements made on the Thermo Scientific NEPTUNE Plus multi-collector ICP-MS that demonstrate the ability to make K-41/K-39 ratio measurements with 0.07% precisions (1sigma). These data, collected on NIST K standards, indicate the potential for MC-ICP-MS measurements to look for K isotopic variations at the sub-permil level. The NEPTUNE Plus can sufficiently resolve 39K and 41K from the interfering 38ArH+ and 40ArH+ peaks in wet cold plasma and high-resolution mode. Measurements were made on small but flat, interference-free, plateaus (ca. 50 ppm by mass width for K-41). Although ICP-MS does not yield accurate K-41/K-39 values due to significant instrumental mass fractionation (ca. 6%), this bias can be sufficiently stable over the time required for several measurements so that relative K-41/K-39 values can be precisely determined via sample

  10. Effect of Wood Aging on Wine Mineral Composition and87Sr/86Sr Isotopic Ratio.

    Science.gov (United States)

    Kaya, Ayse D; Bruno de Sousa, Raúl; Curvelo-Garcia, António S; Ricardo-da-Silva, Jorge M; Catarino, Sofia

    2017-06-14

    The evolution of mineral composition and wine strontium isotopic ratio 87 Sr/ 86 Sr (Sr IR) during wood aging were investigated. A red wine was aged in stainless steel tanks with French oak staves (Quercus sessiliflora Salisb.), with three industrial scale replicates. Sampling was carried out after 30, 60, and 90 days of aging, and the wines were evaluated in terms of general analysis, phenolic composition, total polysaccharides, multielement composition, and Sr IR. Li, Be, Mg, Al, Sc, Ti, V, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Mo, Sb, Cs, Ba, Pr, Nd, Sm, Eu, Dy, Ho, Er, Yb, Lu, Tl, and Pb elements and 87 Sr/ 86 Sr were determined by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) and Na, K, Ca, and Fe by flame atomic absorption spectrometry (FAAS). Two-way ANOVA was applied to assess wood aging and time effect on Sr IR and mineral composition. Wood aging resulted in significantly higher concentrations of Mg, V, Co, Ni, and Sr. At the end of the aging period, wine exhibited statistically identical Sr IR compared to control. Study suggests that wood aging does not affect 87 Sr/ 86 Sr, not precluding the use of this parameter for wine traceability purposes.

  11. High Content Analysis of Compositional Heterogeneities to Study GPCR Oligomerization

    DEFF Research Database (Denmark)

    Walsh, Samuel McEwen

    In this thesis I demonstrate how the natural compositional heterogeneities of synthetic and living cell model systems can be used to quantitate the mechanics of G-protein coupled receptor (GPCR) oligomerization with Förster resonance energy transfer (FRET). The thesis is structured around three a...

  12. Content Discovery from Composite Audio : An unsupervised approach

    NARCIS (Netherlands)

    Lu, L.

    2009-01-01

    In this thesis, we developed and assessed a novel robust and unsupervised framework for semantic inference from composite audio signals. We focused on the problem of detecting audio scenes and grouping them into meaningful clusters. Our approach addressed all major steps in a general process of

  13. Heavy Metal Content and Microbial Composition of the Rhizosphere ...

    African Journals Online (AJOL)

    However, en-hancement of this process for successful phytoremediation processes requires a sound understand-ing of the complex interactions of the rhizosphere. The present study thus investigated the chemi-cal and microbial composition of rhizosphere of Eleusine indica in an auto-mechanic workshop in Benin City.

  14. Effect of chemical composition and alumina content on structure and ...

    Indian Academy of Sciences (India)

    Abstract. In the present work, six electrical porcelain compositions with different amount of alumina and silica have been prepared and fired in an industrial furnace at 1300 ◦C. Density, porosity, bending strength and electrical strength were measured in the samples. In order to find a relationship between properties and ...

  15. Comparison of total phenolic content and composition of individual ...

    African Journals Online (AJOL)

    Ciocalteu method and high-performance liquid chromatography (HPLC), respectively. The total phenolic contents of testae and testa-removed kernels varied from 2.47 ± 0.96 to 84.53 ± 5.57 and 0.07 ± 0.01 to 0.12 ± 0.01 mg gallic acid equivalent ...

  16. Milk fatty acid composition and conjugated linoleic acid content of ...

    African Journals Online (AJOL)

    ... particularly the CLA, omega-3 and omega-6 FA content of the milk fat of Jersey and Fleckvieh x Jersey (F x J) cows in a pasture-based feeding system. All cows were fed the same diet consisting of kikuyu-ryegrass pasture in a rotational grazing system supplemented with a standard commercial concentrate mixture at 7 kg ...

  17. Proximate composition and mineral contents of Pebbly fish, Alestes ...

    African Journals Online (AJOL)

    ACSS

    On wet weight basis, there were no significant differences (p>0.05) in crude protein and ash content among .... hydrochloride before being analysed by cold reduction vaporisationAtomic absorption spectrophotometric .... ionic balance during starvation. The levels of carbohydrate in the present study were low across the fish ...

  18. Determination of the isotopic composition of evapotranspiration in a mature oil palm plantation in Jambi province, Indonesia.

    Science.gov (United States)

    Bonazza, Mattia; Meijide, Ana; Knohl, Alexander

    2017-04-01

    Evapotranspiration (ET) is defined as the sum of the water vapor fluxes from evaporation (E) and transpiration (T). The relative proportion between these two quantities depends on the species, on their age and on the structure of the stand and canopy. Evaporation represents the fraction of water that doesn't contribute to plants growth hence it often considered as "unused" water by the plants root system. For this reason, in a fast changing environment like Indonesia where, since almost 30 years, tropical rainforests are gradually converted into extensive oil palm plantation, it is important to quantify the amount of evaporated water to improve agricultural practices and water quality. As powerful tracers of the hydrological cycle, water stable isotopes represent an important tool to estimate the isotopic composition of the evapotranspiration flux and they can be used as a starting point for the determination of the T/ET ratio, which can be considered as a plant water uptake efficiency indicator. The isotopic composition (δDvand δ18Ov) and the mixing ratio (qv) of water vapor measured in a stand is the result of the isotopic mixing between two members; ecosystem evapotranspiration (δET) and background air (δa). With the implementation of laser-based isotopic analysers we are now able to improve the measurement frequency of δDvand δ18Ov that leads us to an improved estimation of δET. Here we present the results of a measurement campaign, performed with a Picarro L-2120i and conducted in a mature oil palm plantation in the province of Jambi, Indonesia. We measured the atmospheric water vapor mixing ratio and isotopic composition at 5 sampling heights (21 m, 16 m, 9 m, 3.5 and 0.3 m) along a flux tower throughout the oil palm canopy (average height 10 m). The range of the water vapor isotopic composition was between -19 and -11 and -134 and -82 ‰ for δ18Ov and δDvrespectively. A fairly open canopy structure resulted in small mixing ratio gradients along the

  19. Elemental and Sr–Nd isotopic compositional disparity of riverine sediments around the Yellow Sea: Constraints from grain-size and chemical partitioning

    International Nuclear Information System (INIS)

    Lim, Dhongil; Jung, Hoisoo; Xu, Zhaokai; Jeong, Kapsik; Li, Tiegang

    2015-01-01

    To obtain a better understanding of the source compositions of the river sediments around the Yellow Sea and their relationship with source rocks, elements and strontium-neodymium (Sr–Nd) isotopes of different grain-sizes (silt and clay populations) and chemical (labile and residual phases) fractionations in riverine sediments were studied extensively. These results clearly revealed a systematic compositional disparity between Korean river (KR) and Chinese river (CR) sediments, especially in the residual (detrital) fraction. The geochemical dissimilarity between these might reflect inherited signatures of their source rocks but with minor control from chemical weathering. In particular, the remarkable enrichment of some elements (iron (Fe) and magnesium (Mg)) and the behavior of large ion lithophile elements (e.g., barium (Ba), potassium (K) and Sr) during weathering as well as less-radiogenic Sr isotopic compositions implies that CR sediments might be weathering products of relatively more mafic rocks, with abundant ferromagnesian and plagioclase feldspar minerals, compared with KR sediments derived from silicic granites with relatively higher quartz and potassium feldspar contents. This different petrological rationale is clearly evident in an A–CN–K diagram, which estimated the source rock of CR sediments as granodioritic, a composition that reflects accurately the average composition of weathered continental crust in China. The recognition of such geochemical systematics in two river sediments, especially in grain-size and chemically partitioned data, may contribute to the establishment of provenance tracers for the Yellow Sea and East China Sea sediments with multi-sources as well the dust deposition in the western Pacific. - Highlights: • We solved the compositional linkage between river sediments and their source rocks. • Sediments were physically and chemically partitioned for element and Sr–Nd compositions. • Data revealed CR and KR sediments

  20. The precise measurement of TL isotopic compositions by MC-ICPMS: Application to the analysis of geological materials and meteorites.

    Science.gov (United States)

    Rehkämper, Mark; Halliday, Alex N.

    1999-07-01

    The precision of Tl isotopic measurements by thermal ionization mass spectrometry (TIMS) is severely limited by the fact that Tl possesses only two naturally occurring isotopes, such that there is no invariant isotope ratio that can be used to correct for instrumental mass discrimination. In this paper we describe new chemical and mass spectrometric techniques for the determination of Tl isotopic compositions at a level of precision hitherto unattained. Thallium is first separated from the geological matrix using a two-stage anion-exchange procedure. Thallium isotopic compositions are then determined by multiple-collector inductively coupled plasma-mass spectrometry with correction for mass discrimination using the known isotopic composition of Pb that is admixed to the sample solutions. With these procedures we achieve a precision of 0.01-0.02% for Tl isotope ratio measurements in geological samples and this is a factor of ≥3-4 better than the best published results by TIMS. However, without adequate precautions, experimental artifacts can be generated that result in apparent Tl isotopic fractionations of up to one per mil. Analysis of five terrestrial samples indicate the existence of Tl isotopic variations related to natural fractionation processes on the Earth. Two of the three igneous rocks analyzed in this study display Tl isotopic compositions indistinguishable from our laboratory standard, the reference material NIST-997 Tl. A third sample, however, is characterized by ɛ Tl ≈ 2.5 ± 1.5, where ɛ Tl represents the deviation of the 205Tl/ 203Tl ratio of the sample relative to NIST-997 Tl in parts per 10 4. Even larger deviations were identified for two ferromanganese crusts from the Pacific Ocean, which display ɛ Tl-values of +5.0 ± 1.5 and +11.7 ± 1.3. We suggest that the large variability of Tl isotopic compositions in the latter samples are caused by low-temperature processes related to the formation of the Fe-Mn crusts by precipitation and

  1. Variation in the carbon isotopic composition of alkanes during shale gas desorption process and its geological significance

    Directory of Open Access Journals (Sweden)

    Qiang Meng

    2016-04-01

    Full Text Available Taking Chang 7 shale of the Yanchang Formation in the southeastern area of the Yishan slope of the Ordos Basin as our research subject, desorption experiments were performed on more than 30 shale samples that helped this study focus on the variation of carbon isotopic composition of alkanes during the desorption process of shale gas, the possible causes of this phenomenon and its geological significance will also be discussed as follows. It was found that carbon isotopic composition became higher by 9.2‰ (from −50.1‰ to −40.9‰ for methane desorbed gas (δ13C1, and it also became higher by 2.8‰ (from −35.5‰ to −32.7‰ for ethane (δ13C2, but there's barely any differences for propane during the desorption process. At room temperature or constant temperature, carbon isotopic composition for both methane and ethane (δ13C1 & δ13C2 increased continuously. The values of δ13C1 and δ13C2 were low at first and then it gradually became high whilst the desorption process of shale gas that was optimized with the aid of the increasing temperature. The reason for this phenomenon is most likely due to the main adsorption/desorption of shale gas and diffusion migration fractionation of isotope. Additionally, these variation characteristics of methane and ethane carbon isotope composition of shale gas may be a vital reason for the relatively low carbon isotopic composition of methane compared to δ13C calculated by means of the vitrinite reflectance (RO, and this may be applied to evaluate the remaining amount of shale gas resources.

  2. Spatial, seasonal, and source variability in the stable oxygen and hydrogen isotopic composition of tap waters throughout the USA

    Science.gov (United States)

    Landwehr, Jurate M.; Coplen, Tyler B.; Stewart, David W.

    2013-01-01

    To assess spatial, seasonal, and source variability in stable isotopic composition of human drinking waters throughout the entire USA, we have constructed a database of δ18O and δ2H of US tap waters. An additional purpose was to create a publicly available dataset useful for evaluating the forensic applicability of these isotopes for human tissue source geolocation. Samples were obtained at 349 sites, from diverse population centres, grouped by surface hydrologic units for regional comparisons. Samples were taken concurrently during two contrasting seasons, summer and winter. Source supply (surface, groundwater, mixed, and cistern) and system (public and private) types were noted. The isotopic composition of tap waters exhibits large spatial and regional variation within each season as well as significant at-site differences between seasons at many locations, consistent with patterns found in environmental (river and precipitation) waters deriving from hydrologic processes influenced by geographic factors. However, anthropogenic factors, such as the population of a tap’s surrounding community and local availability from diverse sources, also influence the isotopic composition of tap waters. Even within a locale as small as a single metropolitan area, tap waters with greatly differing isotopic compositions can be found, so that tap water within a region may not exhibit the spatial or temporal coherence predicted for environmental water. Such heterogeneities can be confounding factors when attempting forensic inference of source water location, and they underscore the necessity of measurements, not just predictions, with which to characterize the isotopic composition of regional tap waters. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  3. Biochemical composition and caloric content in the sand whiting Sillago sihama (Forsskal), from Zuari Estuary, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Shamsan, E.F.; Ansari, Z.A

    Fish condition as well as the seasonal variation in biochemical composition (moisture content, lipid, protein and carbohydrate) of an economically important fish, Sillago sihama (Forsskal), from Zuari estuary, Goa were monitored over a period...

  4. Proximate Composition and Mineral Content in Different ,Types of

    African Journals Online (AJOL)

    The: concentration of protein in traditional and ... resuiis:in d;je~t types o[togwa wjth yariatiOl? in proximate comfX?sition, energy density and~mirieral content. " . ..... hi the preparation of simulated togwa l .,. "'.' .. IngredientS ,Dtj<: "\\C!~de P~o-.' Ct;ude fi-. Fat: --Ash. Caroo-. Energy matte; r tein (0/0) . ,; bee hydrate value .: (%).

  5. Effect of microtopography on isotopic composition of methane in porewater and efflux at a boreal peatland

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnikov, M.; Wilmking, M. [Greifswald Univ. (Georgia). Inst. of Botany and Landscape Ecology; Marushchak, M.; Biasi, C. [Univ. of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science, Bioteknia 2], E-mail: maxim.dorodnikov@uef.fi

    2013-09-01

    The application of stable isotopes is an approach to identify pathways of methanogenesis, methane (CH{sub 4}) oxidation and transport in peatlands. We measured the stable C isotopic characteristics ({delta}C-13) of CH{sub 4} in peat profiles below hummocks, lawns and hollows of a Finnish mire to study the patterns of CH{sub 4} turnover. Porewater CH{sub 4} concentrations ([CH{sub 4}]; at 0.5-2 m) increased with depth below all microforms. Emissions of CH{sub 4} from hummocks were the lowest, and increased with the increasing water-saturated zone, being {approx}10 times higher from hollows. Thus, the microtopography of the peatland did not affect the porewater [CH{sub 4}] in the water-saturated part of the peat profile, but the CH{sub 4} emissions were affected due to differences in the oxidative potential of the microforms. There was a decrease in {delta}C-13-CH{sub 4} with depth below all microforms indicating dominance of CO{sub 2}-reduction over acetate cleavage pathway of methanogenesis at deep peat layers. However, estimated potential portions of transported CH{sub 4} comprised 50%-70% of the {delta}C-13-CH{sub 4} enrichment on microforms at the 0.5-m depth, hereby masking the acetate cleavage pathway of methanogenesis. Stable C composition ({delta}C-13) of CH{sub 4} proved to be a suitable (but not sufficient) tool to differentiate between types of methanogenesis in continuously water-saturated layers below microforms of a peatland. Combined flux-based and multi-isotopic approaches are needed to better understand the CH{sub 4} turnover process. (orig.)

  6. Characterization of Pu concentration and its isotopic composition in a reference fallout material.

    Science.gov (United States)

    Zhang, Yongsan; Zheng, Jian; Yamada, Masatoshi; Wu, Fengchang; Igarashi, Yasuhito; Hirose, Katsumi

    2010-02-01

    Because there is no reference material for fallout plutonium isotope monitoring, preparation of such a material is necessary for quality control of fallout radionuclides analysis for atmospheric environmental studies. In this work, we report the characterization of Pu activity and its isotopic composition in a reference fallout material prepared by the Meteorological Research Institute (MRI), Japan. This material was prepared from samples collected at 14 stations throughout Japan in 1963-1979, with reference values of (137)Cs, (90)Sr and (239)(+)(240)Pu activities. We analyzed the activities of (239)(+)(240)Pu and (241)Pu, and the atom ratios of (240)Pu/(239)Pu and (241)Pu/(239)Pu using an isotope dilution sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS). The (239)(+)(240)Pu activities in this fallout material using acid leaching and total digestion were 6.56+/-0.20 mBq/g and 6.79+/-0.16 mBq/g, respectively. Atom ratios of (240)Pu/(239)Pu were 0.1915+/-0.0030 and 0.1922+/-0.0044, respectively. Both (240)Pu/(239)Pu and (241)Pu/(239)Pu atom ratios were slightly higher than those of global fallout, which could be attributed to the deposition of fallout radionuclides resulting from the Chinese nuclear weapons tests conducted in the 1970s. The dominant host phases of (239)(+)(240)Pu were found to be organic matter-sulfides (70%) with a relative high (240)Pu/(239)Pu atom ratio, and Fe-Mn oxides (19%) using a sequential extraction method. Copyright 2009 Elsevier B.V. All rights reserved.

  7. Boron isotopic compositions in growing corals from the South China Sea

    Science.gov (United States)

    Xiao, Jun; Xiao, Yingkai; Jin, Zhangdong; Liu, Congqiang; He, Maoyong

    2013-01-01

    In order to determine incorporation of boron species, boron isotopic fractionation, and influence of trace elements on isotopic compositions of boron in corals (δ11Bcoral), concentrations of Mg, Sr, Na, B and δ11Bcoral in growing corals from the South China Sea were measured. Relative to seawater, Sr enriched while Mg depleted in corals in the South China Sea. Although the δ11Bcoral values were different from various species and were not closely correlated with the element concentrations in corals in the South China Sea, Mg(OH)2 existed in corals can result in high δ11Bcoral. Thus, it is necessary to examine the existence of Mg(OH)2 and to choose the same species when δ11Bcoral is used in the δ11B-pH proxy. Based on the measured δ11B values of corals and coexisting seawater as well as the seawater pH in the South China Sea, a new isotopic fractionation factor a4-3 between B(OH)4- and B(OH)3 was determined to be 0.979. Besides B(OH)4- into corals, our results showed that B(OH)3 may also be incorporated into corals with variable proportions. The incorporation of B(OH)3 into corals may challenge the hypothesis of δ11Bcoral = δ11B4, resulting in increasing uncertainty to the calculated seawater pH values to the δ11B-pH proxy. We suggested that a best-fit empirical equation between δ11B of bio-carbonates and seawater pH needs to be established by the precipitation experiments of inorganic carbonates or culture experiments of corals or foraminifera.

  8. Climatic and physiological controls on the stable isotope composition of modern and ancient Cupressaceae

    Science.gov (United States)

    Zinniker, D.; Tipple, B.; Pagani, M.

    2007-12-01

    Unique and abundant secondary metabolites found in waxes and resins of the Callitroid, Cupressoid, and Taxodioid clades of the Cupressaceae family can be identified and quantified in complex mixtures of sedimentary organic compounds. This unusual feature makes it possible to study relatively simple (taxon-specific) isotope systems back in time across the broad array of environments in which these conifers are found. Work on these systems can potentially provide both robust paleoenvironmental proxies (i.e. for source water δD and growing season relative humidity) and quantitative probes into the ecophysiology of these plants in modern and ancient environments. Our research focuses on three genera representing environmental end-members of Cupressaceae - Juniperus, Thuja, and Chamaecyparis - (1) across geographic and environmental gradients in the field, and (2) in specific Holocene and late Pleistocene environmental records. The latter research focuses on peat cores from New England and Oregon and fossil packrat middens from the southwestern United States. Modern transects highlight the sensitivity of Cupressaceae to climatic variables. These include both variables during growth (relative humidity, soil moisture, etc.) and variables affecting seasonal and diurnal growth rates (temperature, winter precipitation, insolation, microhabitat, etc.). Work on ancient records has demonstrated the sensitivity of these unique taxon-specific archives to both subtle and dramatic climate shifts during the Pleistocene and Holocene. This work will result in an improved understanding of climatic and physiological controls on the stable isotopic composition of modern and ancient Cupressaceae - and by extension, other arborescent gymnosperms and C3 plants - providing a framework for understanding more complexly sourced organic inputs to sediments, coals, and petroleum prior to the advent of C4 plants. This research also has direct implications for stratigraphic stable isotope studies

  9. The strontium isotopic composition of seawater, and seawater-oceanic crust interaction

    International Nuclear Information System (INIS)

    Spooner, E.T.C.

    1976-01-01

    The 87 Sr/ 86 Sr ratio of seawater strontium (0.7091) is less than the 87 Sr/ 86 Sr ratio of dissolved strontium delivered to the oceans by continental run-off (approximately 0.716). Isotope exchange with strontium isotopically lighter oceanic crust during hydrothermal convection within spreading oceanic ridges can explain this observation. In quantitative terms, the current 87 Sr/ 86 Sr ratio of seawater (0.7091) may be maintained by balancing the continental run-off flux of strontium (0.59 x 10 12 g/yr) against a hydrothermal recirculation flux of 3.6 x 10 12 g/yr, during which the 87 Sr/ 86 Sr ratio of seawater drops by 0.0011. A concomitant mean increase in the 87 Sr/ 86 Sr ratio of the upper 4.5 km of oceanic crust of 0.0010 (0.7029-0.7039) should be produced. This required 87 Sr enrichment has been observed in hydrothermally metamorphosed ophiolitic rocks from the Troodos Massif, Cyprus. The post-Upper Cretaceous increase in the strontium isotopic composition of seawater (approximately 0.7075-0.7091) covaries smoothly with inferred increase in land area. This suggests that during this period the main factor which has caused variability in the 87 Sr/ 86 Sr ratio of seawater strontium could have been variation in the magnitude of the continental run-off flux caused by variation in land area. Variations in land area may themselves have been partly a consequence of variations in global mean sea-floor spreading rate. (Auth.)

  10. A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

    Science.gov (United States)

    Marty, B; Chaussidon, M; Wiens, R C; Jurewicz, A J G; Burnett, D S

    2011-06-24

    The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.

  11. Contents of selected B vitamins in NIST SRM 3280 multivitamin/multielement tablets by liquid chromatography isotope dilution mass spectrometry.

    Science.gov (United States)

    Chen, Pei; Ozcan, Mustafa; Wolf, Wayne R

    2007-09-01

    There is increased interest in accurately assessing the total dietary intake of vitamins from all sources, including foods and dietary supplements. Consequently, a Dietary Supplement Ingredient Database (DSID), based upon analytical values, is being established by USDA with support of the Office of Dietary Supplements (ODS), NIH. The DSID necessitated the development of a new SRM, 3280--Multivitamin/Multimineral Tablets, by the National Institute of Standards and Technology (NIST), with support from the ODS. As a continuation of a long-term project to develop and validate new methods of determining water-soluble B vitamins in foods and dietary supplements, and as part of a collaborative effort with NIST to characterize SRM 3280, values for the vitamin contents of SRM 3280 have been generated by a liquid chromatographic isotope dilution mass spectrometric (LC/IDMS) method. Isotope-labeled ((13)C and/or (2)H) B vitamins (B1-thiamine, B6-pyridoxine, B3-nicotinamide, and B5-pantothenic acid) were obtained from commercial sources, with the support of the ODS/NIH. Our LC/IDMS method uses a C18 reversed phase column, an Agilent 1100 HPLC system, and a Quattro Micro triple-quad mass spectrometer (MS). B vitamin determination was achieved using a gradient LC profile combined with MS/MS detection in multiple reaction monitoring mode. Stock solutions of the isotope-labeled vitamins were calibrated against USP standard solutions. The SRM tablets, with added amounts of the four isotope-labeled B vitamins, were extracted and the vitamins simultaneously determined in a single LC run, in contrast with the single-component determinations performed via IDMS. Unknown vitamin concentrations were calculated by comparing the ratios of the integrated LC peaks at the different masses of the unlabeled and labeled vitamins.

  12. Correlated silicon and titanium isotopic compositions of presolar SiC grains from the Murchison CM2 chondrite

    Science.gov (United States)

    Gyngard, Frank; Amari, Sachiko; Zinner, Ernst; Marhas, Kuljeet Kaur

    2018-01-01

    We report correlated Si, and Ti isotopic compositions and elemental concentrations of 238 presolar SiC grains from the Murchison CM2 meteorite. Combined with measurements of the C and N isotopic compositions of these 238 grains, 220 were determined to be of type mainstream, 10 type AB, 4 type Y and 4 type Z. SiC grains of diameter ≳2.5 μm, to ensure enough material to attempt Ti measurements, were randomly chosen without any other prejudice. The Ti isotopic compositions of the majority of the grains are characterized by enrichments in 46Ti, 47Ti, 49Ti, and 50Ti relative to 48Ti, and show linear isotopic correlations indicative of galactic chemical evolution and neutron capture of the grains parent stars. The variability in the observed Ti signal as a function of depth in most of the grains indicates the presence of distinct subgrains, likely TiC that have been previously observed in TEM studies. Vandium-51 concentrations correlate with those of Ti, indicating V substitutes for Ti in the TiC matrix in many of the grains. No isotopic anomalies in 52Cr/53Cr ratios were observed, and Cr concentrations did not correlate with those of either Ti or V.

  13. Temporal variations of methane concentration and isotopic composition in groundwater of the St. Lawrence Lowlands, eastern Canada

    Science.gov (United States)

    Rivard, Christine; Bordeleau, Geneviève; Lavoie, Denis; Lefebvre, René; Malet, Xavier

    2018-03-01

    Dissolved methane concentrations in shallow groundwater are known to vary both spatially and temporally. The extent of these variations is poorly documented although this knowledge is critical for distinguishing natural fluctuations from anthropogenic impacts stemming from oil and gas activities. This issue was addressed as part of a groundwater research project aiming to assess the risk of shale gas development for groundwater quality over a 500-km2 area in the St. Lawrence Lowlands (Quebec, Canada). A specific study was carried out to define the natural variability of methane concentrations and carbon and hydrogen isotope ratios in groundwater, as dissolved methane is naturally ubiquitous in aquifers of this area. Monitoring was carried out over a period of up to 2.5 years in seven monitoring wells. Results showed that for a given well, using the same sampling depth and technique, methane concentrations can vary over time from 2.5 to 6 times relative to the lowest recorded value. Methane isotopic composition, which is a useful tool to distinguish gas origin, was found to be stable for most wells, but varied significantly over time in the two wells where methane concentrations are the lowest. The use of concentration ratios, as well as isotopic composition of methane and dissolved inorganic carbon (DIC), helped unravel the processes responsible for these variations. This study indicates that both methane concentrations and isotopic composition, as well as DIC isotopes, should be regularly monitored over at least 1 year to establish their potential natural variations prior to hydrocarbon development.

  14. Origin of magnetite in oxidized CV chondrites: in situ measurement of oxygen isotope compositions of Allende magnetite and olivine

    Science.gov (United States)

    Choi, B. G.; McKeegan, K. D.; Leshin, L. A.; Wasson, J. T.

    1997-01-01

    Magnetite in the oxidized CV chondrite Allende mainly occurs as spherical nodules in porphyritic-olivine (PO) chondrules, where it is associated with Ni-rich metal and/or sulfides. To help constrain the origin of the magnetite, we measured oxygen isotopic compositions of magnetite and coexisting olivine grains in PO chondrules of Allende by an in situ ion microprobe technique. Five magnetite nodules form a relatively tight cluster in oxygen isotopic composition with delta 18O values from -4.8 to -7.1% and delta 17O values from -2.9 to -6.3%. Seven coexisting olivine grains have oxygen isotopic compositions from -0.9 to -6.3% in delta 18O and from -4.6 to -7.9% in delta 17O. The delta 17O values of the magnetite and coexisting olivine do not overlap; they range from -0.4 to -2.6%, and from -4.0 to -5.7%, respectively. Thus, the magnetite is not in isotopic equilibrium with the olivine in PO chondrules, implying that it formed after the chondrule formation. The delta 17O of the magnetite is somewhat more negative than estimates for the ambient solar nebula gas. We infer that the magnetite formed on the parent asteroid by oxidation of metal by H2O which had previously experienced minor O isotope exchange with fine-grained silicates.

  15. [Monosaccharide composition analysis and its content determination of polysaccharides from Rhaponticum uniforum].

    Science.gov (United States)

    Li, Fa-Sheng; Xu, Heng-Gui; Yan, Xiao-Mei; Li, Ming-Yang; Liu, Hui

    2008-06-01

    To analyze the monosaccharide composition in the polysaccharides from Rhaponticum uniforum, determine the content of monosaccharide, and provide some references for further research. The monosaccharide composition was determined by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Phenol-sulfuric acid method was used for the determination of the content of polysaccharide. The monosaccharides composition in polysaccharides from R. uniforum are glucose, arabonose and fructose. Their molar ratios are 1 : 1.61 : 2.21. The content of polysaccharide is 95.78%, taking the mixture of monosaccharide compositions as reference substances. HPAEC-PAD can be used to analyze the monosaccharide composition in the polysaccharide with high precision, and the method of phenol-sulfuric acid is simple, convenient and reliable.

  16. A model composition for Mars derived from the oxygen isotopic ratios of martian/SNC meteorites. [Abstract only

    Science.gov (United States)

    Delaney, J. S.

    1994-01-01

    Oxygen is the most abundant element in most meteorites, yet the ratios of its isotopes are seldom used to constrain the compositional history of achondrites. The two major achondrite groups have O isotope signatures that differ from any plausible chondritic precursors and lie between the ordinary and carbonaceous chondrite domains. If the assumption is made that the present global sampling of chondritic meteorites reflects the variability of O reservoirs at the time of planetessimal/planet aggregation in the early nebula, then the O in these groups must reflect mixing between known chondritic reservoirs. This approach, in combination with constraints based on Fe-Mn-Mg systematics, has been used previously to model the composition of the basaltic achondrite parent body (BAP) and provides a model precursor composition that is generally consistent with previous eucrite parent body (EPB) estimates. The same approach is applied to Mars exploiting the assumption that the SNC and related meteorites sample the martian lithosphere. Model planet and planetesimal compositions can be derived by mixing of known chondritic components using O isotope ratios as the fundamental compositional constraint. The major- and minor-element composition for Mars derived here and that derived previously for the basaltic achondrite parent body are, in many respects, compatible with model compositions generated using completely independent constraints. The role of volatile elements and alkalis in particular remains a major difficulty in applying such models.

  17. Improved Sensitivity of Spectroscopic Quantification of Stable Isotope Content Using Capillary Absorption Spectroscopy

    Science.gov (United States)

    Moran, J.; Wilcox Freeburg, E.; Kriesel, J.; Linley, T. J.; Kelly, J.; Coleman, M. L.; Christensen, L. E.; Vance, S.

    2016-12-01

    Spectroscopy-based platforms have recently risen to the forefront for making stable isotope measurements of methane, carbon dioxide, water, or other analytes. These spectroscopy systems can be relatively straightforward to operate (versus a mass spectrometry platform), largely relieve the analyst of mass interference artifacts, and many can be used in the field. Despite these significant advantages, however, existing spectroscopy techniques suffer from a lack of measurement sensitivity that can ultimately limit select applications including spatially resolved and compound-specific measurements. Here we present a capillary absorption spectroscopy (CAS) system that is designed to mitigate sensitivity issues in spectroscopy-based stable isotope evaluation. The system uses mid-wave infrared excitation generated from a continuous wave quantum cascade laser. Importantly, the sample `chamber' is a flexible capillary with a total volume of less than one cc. Proprietary coatings on the internal surface of the fiber improve optical performance, guiding the light to a detector and facilitating high levels of interaction between the laser beam and gaseous analytes. We present data demonstrating that a tapered hollow fiber cell, with an internal diameter that broadens toward the detector, reduces optical feedback to further improve measurement sensitivity. Sensitivity of current hollow fiber / CAS systems enable measurements of only 10's of picomoles CO2 while theoretical improvements should enable measurements of as little as 10's of femtomoles. Continued optimization of sample introduction and improvements to optical feedback are being explored. Software is being designed to provide rapid integration of data and generation of processed isotope measurements using a graphical user interface. Taken together, the sensitivity improvements of the CAS system under development could, when coupled to a laser ablation sampling device, enable up to 2 µm spatial resolution (roughly the

  18. Stable isotope compositions of serpentinite seamounts in the Mariana forearc: Serpentinization processes, fluid sources and sulfur metasomatism

    Science.gov (United States)

    Alt, J.C.; Shanks, Wayne C.

    2006-01-01

    The Mariana and Izu-Bonin arcs in the western Pacific are characterized by serpentinite seamounts in the forearc that provide unique windows into the mantle wedge. We present stable isotope (O, H, S, and C) data for serpentinites from Conical seamount in the Mariana forearc and S isotope data for Torishima seamount in the Izu-Bonin forearc in order to understand the compositions of fluids and temperatures of serpentinization in the mantle wedge, and to investigate the transport of sulfur from the slab to the mantle wedge. Six serpentine mineral separates have a restricted range of ??18O (6.5-8.5???). Antigorite separates have ??D values of -29.5??? to -45.5??? that reflect serpentinization within the mantle wedge whereas chrysotile has low ??D values (-51.8??? to -84.0???) as the result of re-equilibration with fluids at low temperatures. Fractionation of oxygen isotopes between serpentine and magnetite indicate serpentinization temperatures of 300-375 ??C. Two late cross-fiber chrysotile veins have higher ??18O values of 8.9??? to 10.8??? and formed at lower temperatures (as low as ???100 ??C). Aqueous fluids in equilibrium with serpentine at 300-375 ??C had ??18O = 6.5-9??? and ??D = -4??? to -26???, consistent with sediment dehydration reactions at temperatures aragonite veins in metabasalt and siltstone clasts within the serpentinite flows have ??18O = 16.7-24.5???, consistent with the serpentinizing fluids at temperatures <250 ??C. ??13C values of 0.1-2.5??? suggest a source in subducting carbonate sediments. The ??34S values of sulfide in serpentinites on Conical Seamount (-6.7??? to 9.8???) result from metasomatism through variable reduction of aqueous sulfate (??34S = 14???) derived from slab sediments. Despite sulfur metasomatism, serpentinites have low sulfur contents (generally < 164 ppm) that reflect the highly depleted nature of the mantle wedge. The serpentinites are mostly enriched in 34S (median ??34Ssulfide = 4.5???), consistent with a 34S

  19. Relationships Among Intrinsic Properties of Ordinary Chondrites: Oxidation State, Bulk Chemistry, Oxygen-isotopic Composition, Petrologic Type, and Chondrule Size

    Science.gov (United States)

    Rubin, Alan E.

    2006-01-01

    The properties of ordinary chondrites (OC) reflect both nebular and asteroidal processes. OC are modeled here as having acquired nebular water, probably contained within phyllosilicates, during agglomeration. This component had high Ai70 and acted like an oxidizing agent during thermal metamorphism. The nebular origin of this component is consistent with negative correlations in H, L, and LL chondrites between oxidation state (represented by olivine Fa) and bulk concentration ratios of elements involved in the metal-silicate fractionation (e.g., NdSi, Ir/Si, Ir/Mn, Ir/Cr, Ir/Mg, Ni/Mg, As/Mg, Ga/Mg). LL chondrites acquired the greatest abundance of phyllosilicates with high (delta)O-17 among OC (and thus became the most oxidized group and the one with the heaviest O isotopes); H chondrites acquired the lowest abundance, becoming the most reduced OC group with the lightest O isotopes. Chondrule precursors may have grown larger and more ferroan with time in each OC agglomeration zone. Nebular turbulence may have controlled the sizes of chondrule precursors. H-chondrite chondrules (which are the smallest among OC) formed from the smallest precursors. In each OC region, low-FeO chondrules formed before high-FeO chondrules during repeated episodes of chondrule formation. During thermal metamorphism, phyllosilicates were dehydrated; the liberated water oxidized metallic Fe-Ni. This caused correlated changes with petrologic type including decreases in the modal abundance of metal, increases in olivine Fa and low-Ca pyroxene Fs, increases in the olivine/pyroxene ratio, and increases in the kamacite Co and Ni contents. As water (with its heavy 0 isotopes) was lost during metamorphism, inverse correlations between bulk (delta)O-18 and bulk (delta)O-17 with petrologic type were produced. The H5 chondrites that were ejected from their parent body approx.7.5 Ma ago during a major impact event probably had been within a few kilometers of each other since they accreted approx.4

  20. Stable isotope and chemical composition of pearls - Biomineralization in cultured pearl oysters in Ago Bay, Japan -

    Science.gov (United States)

    Kawahata, H.; Inoue, M.; Suzuki, A.

    2004-12-01

    1. The oxygen isotopic composition of the pearl suggests that these pearls were produced around 23 degree centigrade, mainly in June, which is consistent with their occurrence in the field. In spite of high growth rate (higher than 0.2-1 g per year), where coral skeleton (~0.1 g per year) often presents non-equilibrium isotope partitioning, the pearls show complete or close to equilibrium condition. 2. The pearl samples showed rather scattered delta carbon 13 values (-1.04 - +0.47per mil, av. -0.16per mil) compared with delta oxygen 18 values. The delta carbon 13 values are ~-2.9per mil lower than those calculated from those in offshore water. It may be affected by low-delta carbon 13 waters due to degradation of organic matter in the Ba or by low-delta carbon 13 food. In the latter case, a simple mass balance calculation gives respiration component of 14%. 3. 12 trace elements of bulk pearl samples were classified into 4 groups: Group 1 (Co, Cr, Pb), Group 2 (Ba, Cs, U), Group 3 (Cu, Sn, V) and Group 4 (other elements such as Mn, Rb, Mo).Comparison with coral chemistry suggests that proteinous organic matter contain abundant Ba and Mn and significant amount of elements of Group.

  1. Study of the carbon and oxygen isotopic compositions in marine shells of Salvador-Bahia, Brazil

    International Nuclear Information System (INIS)

    Freitas, J.C.B. de.

    1977-01-01

    The carbon and oxygen isotopic composition of 68 samples of marine shells from the region of Salvador was determined. These samples are from points on the open coast and in the interior of the Todos os Santos Bay and they are composed in part by recent specimens and in part by old specimens taken from Quaternary sediments. The results for δ 18 O are in the range of -2,83per mille to + 1,21per mille (PDB) and for δ 13 C in the range of -3,10per mille to +2,63per mille (PDB). The reults for the recent shells from the interior of the Todos os Santos Bay show variations in the δ 13 C values associated to the dominance of organic matter in some regions. For the old samoles, gathered in te variations in the δ 13 C values was associated to the existence in points of that region of deposits of fluvio-lagunar sediments, originated during the last marine transgression. It was identified, for a few species with the same age and location, the effect of biological fractionations. Nevertheless, the observed dominant factor on the isotopic differentiation was the environmental fractionation. (Author) [pt

  2. Rhodium self-powered detector for monitoring neutron fluence, energy production, and isotopic composition of fuel

    International Nuclear Information System (INIS)

    Sokolov, A.P.; Pochivalin, G.P.; Shipovskikh, Yu.M.; Garusov, Yu.V.; Chernikov, O.G.; Shevchenko, V.G.

    1993-01-01

    The use of self-powered detectors (SPDs) with a rhodium emitter customarily involves monitoring of neutron fields in the core of a nuclear reactor. Since current in an SPD is generated primarily because of the neutron flux, which is responsible for the dynamics of particular nuclear transformations, including fission reactions of heavy isotopes, the detector signal can be attributed unambiguously to energy release at the location of the detector. Computation modeling performed with the KOMDPS package of programs of the current formation in a rhodium SPD along with the neutron-physical processes that occur in the reactor core makes it possible to take account of the effect of the principal factors characterizing the operating conditions and the design features of the fuel channel and the detector, reveal quantitative relations between the generated signal and individual physical parameters, and determine the metrological parameters of the detector. The formation and transport of changed particles in the sensitive part of the SPC is calculated by the Monte Carlo method. The emitter activation, neutron transport, and dynamics of the isotopic composition in the fuel channel containing the SPD are determined by solving the kinetic equation in the multigroup representation of the neutron spectrum, using the discrete ordinate method. In this work the authors consider the operation of a rhodium SPD in a bundle of 49 fuel channels of the RBMK-1000 reactor with a fuel enrichment of 2.4% from the time it is inserted into a fresh channel

  3. Concentration and stable carbon isotopic composition of CO2 in cave air of Postojnska jama, Slovenia

    Directory of Open Access Journals (Sweden)

    Magda Mandic

    2013-09-01

    Full Text Available Partial pressure of CO2 (pCO2 and its isotopic composition (δ13CairCO2 were measured in Postojnska jama, Slovenia, at 10 locations inside the cave and outside the cave during a one-year period. At all interior locations the pCO2 was higher and δ13CairCO2 lower than in the outside atmosphere. Strong seasonal fluctuations in both parameters were observed at locations deeper in the cave, which are isolated from the cave air circulation. By using a binary mixing model of two sources of CO2, one of them being the atmospheric CO2, we show that the excess of CO2 in the cave air has a δ13C value of -23.3 ± 0.7 ‰, in reasonable agreement with the previously measured soil-CO2 δ13C values. The stable isotope data suggest that soil CO2 is brought to the cave by drip water.

  4. Nitrogen Isotope Composition of Thermally Produced NOx from Various Fossil-Fuel Combustion Sources.

    Science.gov (United States)

    Walters, Wendell W; Tharp, Bruce D; Fang, Huan; Kozak, Brian J; Michalski, Greg

    2015-10-06

    The nitrogen stable isotope composition of NOx (δ(15)N-NOx) may be a useful indicator for NOx source partitioning, which would help constrain NOx source contributions in nitrogen deposition studies. However, there is large uncertainty in the δ(15)N-NOx values for anthropogenic sources other than on-road vehicles and coal-fired energy generating units. To this end, this study presents a broad analysis of δ(15)N-NOx from several fossil-fuel combustion sources that includes: airplanes, gasoline-powered vehicles not equipped with a three-way catalytic converter, lawn equipment, utility vehicles, urban buses, semitrucks, residential gas furnaces, and natural-gas-fired power plants. A relatively large range of δ(15)N-NOx values was measured from -28.1‰ to 8.5‰ for individual exhaust/flue samples that generally tended to be negative due to the kinetic isotope effect associated with thermal NOx production. A negative correlation between NOx concentrations and δ(15)N-NOx for fossil-fuel combustion sources equipped with selective catalytic reducers was observed, suggesting that the catalytic reduction of NOx increases δ(15)N-NOx values relative to the NOx produced through fossil-fuel combustion processes. Combining the δ(15)N-NOx measured in this study with previous published values, a δ(15)N-NOx regional and seasonal isoscape was constructed for the contiguous U.S., which demonstrates seasonal and regional importance of various NOx sources.

  5. The chromium isotopic composition of an Early to Middle Ordovician marine carbonate platform, eastern Precordillera, San Juan, Argentina

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary; Frei, Robert; Gilleaudeau, Geoffrey Jon

    of seawater is controlled by inputs from oxidative weathering on land and redox transformations in marine environments. Preliminary results indicate a major shift in d53Cr values from +0.5‰ to 0‰ across the Early to Middle Ordovician boundary, accompanied by an increase in Cr concentration from 0.1 to 0......-existing pyrite in the later Middle Ordovician are consistent with oxygen mixing at depth and ventilation of euxinic bottom waters [4]. We measured the Cr isotopic composition of an Early to Middle Ordovician carbonate platform to test whether Cr isotopes record ocean oxygenation. The Cr isotopic composition....... This hypothesized change in redox at the Early to Middle Ordovician boundary may preface more widespread ventilation in the later Middle Ordovician. [1] Hurtgen et al., 2009, EPSL v 281 p. 288-297 [2] Gill et al., 2011, GEOCHIM COSOCHIM AC v 72 p. 4699-4711 [3] Thompson and Kah, 2012 Palaeogeogr. Palaeoclimatol...

  6. Lead Isotopic Compositions of Selected Coals, Pb/Zn Ores and Fuels in China and the Application for Source Tracing.

    Science.gov (United States)

    Bi, Xiang-Yang; Li, Zhong-Gen; Wang, Shu-Xiao; Zhang, Lei; Xu, Rui; Liu, Jin-Ling; Yang, Hong-Mei; Guo, Ming-Zhi

    2017-11-21

    Lead (Pb) pollution emission from China is becoming a potential worldwide threat. Pb isotopic composition analysis is a useful tool to accurately trace the Pb sources of aerosols in atmosphere. In this study, a comprehensive data set of Pb isotopes for coals, Pb/Zn ores, and fuels from China was presented. The ratios of 206 Pb/ 207 Pb and 208 Pb/ 206 Pb in the coals were in the range of 1.114-1.383 and 1.791-2.317, similar to those from Europe, Oceania, and South Asia, but different from those from America (p fuels from in coals. Urban aerosols demonstrated similar Pb isotopic compositions to coals, Pb/Zn ores, and fuels in China. After removing the leaded gasoline, the Pb in aerosols is more radiogenic, supporting the heavy contribution of coal combustion to the atmospheric Pb pollution.

  7. Development of a portable mass spectrometric system for determination of isotopic composition of solid uranium samples using fluorine volatilization

    Science.gov (United States)

    Loge, G.

    1994-09-01

    Using hardware and materials supplied by LANL, a prototype quadrupole mass spectrometer system designed for portable field analysis of isotopic composition of solid uranium samples was assembled and tested. The system contained the capability for fluorine volatilization of solid uranium samples with gas introduction, which was successfully tested and demonstrated using 100 mg samples of U3O8. Determination of precision and accuracy for measuring isotopic composition was performed using isotopic standards. Use with soil samples containing uranium were also attempted. Silicates in the soil forming SiF4 were found to be a kinetic bottleneck to the formation of UF6. This could be avoided by performing some sort of chemical separation as a pre-treatment step, which was demonstrated using nitric acid.

  8. Effect of fiber content on the properties of glass fiber-phenolic matrix composite

    International Nuclear Information System (INIS)

    Zaki, M.Y.; Shahid, M.R.; Subhani, T.; Sharif, M.N.

    2003-01-01

    Glass fiber-Phenolic matrix composite is used for the manufacturing of parts /components related to electronic and aerospace industry due to its high strength, dimensional stability and excellent electrical insulation properties. The evaluation of this composite material is necessary prior to make parts/components of new designs. In the present research, thermosetting phenolic plastic was reinforced with E-glass fiber in different fiber-to-resin ratios to produce composites of different compositions. Mechanical and electrical properties of these composite materials were evaluated with reference to the effect of fiber content variation in phenolic resin. (author)

  9. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA

    International Nuclear Information System (INIS)

    Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita

    2013-01-01

    Highlights: ► Hg and Pb concentration and isotopic compositions traced anthropogenic sources. ► Concentrations and metal loadings of Hg and Pb increased during the smelting period. ► Hg isotopic compositions changed during smelting compared to the pre-smelting period. ► Data indicate mass independent fractionation of Hg isotopes. - Abstract: Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ 202 Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ 202 Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206 Pb/ 207 Pb and 208 Pb/ 207 Pb isotopic compositions during these periods. Data for Δ 199 Hg and Δ 201 Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ 199 Hg and Δ 201 Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger

  10. Spatiotemporal variability of oxygen isotope compositions in three contrasting glacier river catchments in Greenland

    DEFF Research Database (Denmark)

    Knudsen, N. Tvis; Yde, J.C.; Steffensen, J.P.

    2015-01-01

    Analysis of stable oxygen isotope (δ18O) characteristics is a useful tool to investigate water provenance in glacier river systems. In order to attain knowledge on the diversity of spatio-temporal δ18O variations in glacier rivers, we have examined three glacierized catchments in Greenland...... composition is controlled by the proportion between snowmelt and ice melt with episodic inputs of rainwater and occasional storage and release of a specific water component due to changes in the subglacial drainage system. At Kuannersuit Glacier River on the island Qeqertarsuaq, the δ18O characteristics were...... sampling indicates that during the early melt season most of the river water (64–73 %) derived from the Qinnguata Kuussua tributary, whereas the water flow on 23 July 2009 was dominated by bulk meltwater from the Akuliarusiarsuup Kuua tributary (where 7 and 67 % originated from the Russell Glacier...

  11. Nitrogen Isotopic Composition of Organic Matter in a Pristine Collection IDP

    Science.gov (United States)

    Messenger, S.; Nakamura-Messenger, K.; Keller, L. P.; Clemett, S. J.; Nguyen, A. N.; Walker, Robert M.

    2012-01-01

    Anhydrous chondritic porous interplanetary dust particles (CP IDPs) are probable cometary materials that show primitive characteristics, such as unequilibrated mineralogy, fragile structure, and abundant presolar grains and organic matter [1-3]. CP IDPs are richer in aliphatic species and N-bearing aromatic hydrocarbons than meteoritic organics and commonly exhibit highly anomalous H and N isotopic compositions [4,5]. Cometary organic matter is of interest in part because it has escaped the hydrothermal processing experienced by meteorites. However, IDPs are collected using silicon oil that must be removed with strong organic solvents such as hexane. This procedure is likely to have removed some fraction of soluble organic phases in IDPs. We recently reported the first stratospheric collection of IDPs without the use of silicone oil [6]. Here we present initial studies of the carbonaceous material in an IDP from this collection.

  12. Experimental evaporation of hyperacid brines: Effects on chemical composition and chlorine isotope fractionation

    Science.gov (United States)

    Rodríguez, Alejandro; van Bergen, Manfred J.; Eggenkamp, H. G. M.

    2018-02-01

    Hyperacid brines from active volcanic lakes are some of the chemically most complex aqueous solutions on Earth. Their compositions provide valuable insights into processes of elemental transfer from a magma body to the surface and interactions with solid rocks and the atmosphere. This paper describes changes in chemical and δ37Cl signatures observed in a 1750 h isothermal evaporation experiment on hyperacid (pH 0.1) sulphate-chloride brine water from the active lake of Kawah Ijen volcano (Indonesia). Although gypsum was the only evaporite mineral identified in the evolving brine, decreasing Si concentrations may ultimately result in amorphous silica precipitation. Geochemical simulations predict the additional formation of elemental sulphur at lower water activities (aH2O ≤ 0.65) that were not reached in the experiment. Absence of other sulphates and halides despite the high load of dissolved elements (initial TDS ca. 100 g/kg) can be attributed to increased solubility of metals, promoted by extensive formation of complexes between the variety of cations and the major anions (HSO4-, Cl-, F-) present. Chlorine deviations from a conservative behaviour point to losses of gaseous hydrogen chloride (HCl(g)) and consequently an increase in Br/Cl ratios. Chlorine isotope fractionation that accompanied the escape of HCl(g) showed a marked change in sign and magnitude in the course of progressive evaporation of the brine. The calculated factor of fractionation between HCl(g) and dissolved Cl for the initial interval (before 500 h) is positive (1000lnαHCl(g)-Cldiss. = + 1.55 ± 0.49‰to + 3.37 ± 1.11‰), indicating that, at first, the escaping HCl(g) was isotopically heavier than the dissolved Cl remaining in the brine. Conversely, fractionation shifted to the opposite direction in the subsequent interval (1000lnαHCl(g)-Cldiss. = 5.67 ± 0.17‰to - 5.64 ± 0.08‰), in agreement with values reported in literature. It is proposed that Cl isotopic fractionation in

  13. An improved method for determination of uranium isotopic composition in urine by alpha spectrometry

    International Nuclear Information System (INIS)

    Duarte, C.L.; Szeles, M.S.M.F.

    1994-01-01

    A comparative study of source preparation techniques to determine uranium isotopic composition by alpha spectrometry, namely electrodeposition and chemical stripping with polymeric membrane containing trioctylphosphine oxide (TOPO), is presented. The mean yield obtained for electrodeposition and TOPO deposition were 85% and 74%, respectively. The mean activity ratio 235 U/ 238 U were 0.044 and 0.042 and the ratio 234 U/ 238 U were 0.994 and 1.009, using electrodeposition and TOPO deposition techniques, respectively. The method of uranium separation from urine using an ion-exchange resin Dowex 1 x 8, chloride form and citrate form, was also studied. The obtained global yields of these methods were 50% and 41%, respectively. (author)

  14. Bayesian estimation of predator diet composition from fatty acids and stable isotopes

    Directory of Open Access Journals (Sweden)

    Philipp Neubauer

    2015-04-01

    Full Text Available Quantitative analysis of stable isotopes (SI and, more recently, fatty acid profiles (FAP are useful and complementary tools for estimating the relative contribution of different prey items in the diet of a predator. The combination of these two approaches, however, has thus far been limited and qualitative. We propose a mixing model for FAP that follows the Bayesian machinery employed in state-of-the-art mixing models for SI. This framework provides both point estimates and probability distributions for individual and population level diet proportions. Where fat content and conversion coefficients are available, they can be used to improve diet estimates. This model can be explicitly integrated with analogous models for SI to increase resolution and clarify predator–prey relationships. We apply our model to simulated data and an experimental dataset that allows us to illustrate modeling strategies and demonstrate model performance. Our methods are provided as an open source software package for the statistical computing environment R.

  15. Temporal changes in Nd isotopic composition of Piton de la Fournaise magmatism (Réunion Island, Indian Ocean)

    Science.gov (United States)

    Luais, BéAtrice

    2004-01-01

    A Nd isotopic study of twelve historical samples and fifty-seven core samples covering the last 530 ka of volcanic activity of the Piton de la Fournaise volcano of Réunion Island was undertaken, with additional new Sr isotopic analyses of historical samples. The core samples were obtained from the cliffs of the deep (ca.1000 m) canyons of the Remparts and Langevin Rivers. Four types of rocks, namely basalts (MgO = 5-9 wt.%), high-Mg basalts (MgO = 10-20 wt.%), plagioclase-rich basalts, and differentiated samples (SiO2 = 48-53 wt.%) occur randomly throughout the lava sections. The overall variations in Nd isotopic ratios (0.512751 to 0.512902) are small, but significant. The range of Nd isotopic variations is larger than previously described in the literature, and extends toward lower values. Nd isotopic ratios increase through time and are broadly negatively correlated with the alkalinity index. The older alkaline Remparts samples (527-290 ka) (average ɛNd = +3.26) exhibit lower 143Nd/144Nd ratios than the younger tholeiitic Langevin samples (70-40 ka) (average ɛNd = +4.17) and the historical lavas (1901-1956) (average ɛNd = +4.74). Comparison of 143Nd/144Nd ratios with available 87Sr/86Sr ratios on the same set of samples (Remparts and Langevin series [Albarède et al., 1997]; historical series, this study) shows no correlation between Sr and Nd isotopes. It is suggested that the high Nd isotopic ratios of historical tholeiitic samples would be representative of the isotopic composition of the Réunion plume. The increase in Nd isotopic ratios over 530 ka reflects the effect of decreasing contribution of an enriched component to the Réunion plume through time. This enriched component would occur as isolated blobs in the mantle source.

  16. Delta Chromium-53/52 isotopic composition of native and contaminated groundwater, Mojave Desert, USA

    International Nuclear Information System (INIS)

    Izbicki, John A.; Bullen, Thomas D.; Martin, Peter; Schroth, Brian

    2012-01-01

    Chromium(VI) concentrations in groundwater sampled from three contaminant plumes in aquifers in the Mojave Desert near Hinkley, Topock and El Mirage, California, USA, were as high as 2600, 5800 and 330 μg/L, respectively. δ 53/52 Cr compositions from more than 50 samples collected within these plumes ranged from near 0‰ to almost 4‰ near the plume margins. Assuming only reductive fractionation of Cr(VI) to Cr(III) within the plume, apparent fractionation factors for δ 53/52 Cr isotopes ranged from ε app = 0.3 to 0.4 within the Hinkley and Topock plumes, respectively, and only the El Mirage plume had a fractionation factor similar to the laboratory derived value of ε = 3.5. One possible explanation for the difference between field and laboratory fractionation factors at the Hinkley and Topock sites is localized reductive fractionation of Cr(VI) to Cr(III), with subsequent advective mixing of native and contaminated water near the plume margin. Chromium(VI) concentrations and δ 53/52 Cr isotopic compositions did not uniquely define the source of Cr near the plume margin, or the extent of reductive fractionation within the plume. However, Cr(VI) and δ 53/52 Cr data contribute to understanding of the interaction between reductive and mixing processes that occur within and near the margins of Cr contamination plumes. Reductive fractionation of Cr(VI) predominates in plumes having higher ε app , these plumes may be suitable for monitored natural attenuation. In contrast, advective mixing predominates in plumes having lower ε app , the highly dispersed margins of these plumes may be difficult to define and manage.

  17. Delta Chromium-53/52 isotopic composition of native and contaminated groundwater, Mojave Desert, USA

    Science.gov (United States)

    Izbicki, John A.; Bullen, Thomas D.; Martin, Peter; Schroth, Brian

    2012-01-01

    Chromium(VI) concentrations in groundwater sampled from three contaminant plumes in aquifers in the Mojave Desert near Hinkley, Topock and El Mirage, California, USA, were as high as 2600, 5800 and 330 μg/L, respectively. δ53/52Cr compositions from more than 50 samples collected within these plumes ranged from near 0‰ to almost 4‰ near the plume margins. Assuming only reductive fractionation of Cr(VI) to Cr(III) within the plume, apparent fractionation factors for δ53/52Cr isotopes ranged from εapp = 0.3 to 0.4 within the Hinkley and Topock plumes, respectively, and only the El Mirage plume had a fractionation factor similar to the laboratory derived value of ε = 3.5. One possible explanation for the difference between field and laboratory fractionation factors at the Hinkley and Topock sites is localized reductive fractionation of Cr(VI) to Cr(III), with subsequent advective mixing of native and contaminated water near the plume margin. Chromium(VI) concentrations and δ53/52Cr isotopic compositions did not uniquely define the source of Cr near the plume margin, or the extent of reductive fractionation within the plume. However, Cr(VI) and δ53/52Cr data contribute to understanding of the interaction between reductive and mixing processes that occur within and near the margins of Cr contamination plumes. Reductive fractionation of Cr(VI) predominates in plumes having higher εapp, these plumes may be suitable for monitored natural attenuation. In contrast, advective mixing predominates in plumes having lower εapp, the highly dispersed margins of these plumes may be difficult to define and manage.

  18. Nitrogen isotopic composition of enameloid-bound organic matter from modern and fossil shark teeth

    Science.gov (United States)

    Kast, E.; Wang, X. T.; Kim, S.; Kocsis, L.; Sigman, D. M.

    2016-12-01

    The nitrogen isotopic composition of fossil organic matter has been used to reconstruct ocean biogeochemical conditions in the past, and there is the potential for such investigations to be extended to trophic and ecological processes. Organic matter trapped within biogenic minerals is of particular interest for this purpose because of relatively good preservation and specificity when compared to bulk sedimentary organic matter. The approach for measuring mineral bound organic matter δ15N previously applied to diatoms, foraminifera, and coral skeleton has been adapted for use with tooth apatite, with reproducibility within 0.25‰ for modern and fossil shark enameloid. Studies of modern shark enameloid bound δ15N (δ15NEB) show substantial variability ( 3‰) between individuals of a single species and in some cases among teeth from a given individual. δ15NEB is affected by the isotopic composition of nutrient supply, which is a primary determinant of the δ15N at the base of the food web, and progressive 15N enrichment with trophic level due to the metabolism and excretion of low-δ15N N. Among modern shark species studied, patterns in δ15NEB appear to primarily reflect regional variations in subsurface nitrate δ15N, with the trophic effect as a secondary signal, in part because trophic level does not vary greatly across the studied shark species (or, indeed, across many shark species). Teeth from individual jaws can show trends in δ15NEB with the age of the tooth, possibly representing a dietary shift or seasonal migration. The modern measurements suggest that, with care, enameloid bound δ15N can be used to reconstruct past nutrient cycling dynamics. In this context, measurements will be presented of δ15NEB from fossil shark teeth of various Cenozoic ages from the Atlantic basin.

  19. Chlorine isotope composition of volcanic rocks and gases at Stromboli volcano (Aeolian Islands, Italy): Inferences on magmatic degassing prior to 2014 eruption

    Science.gov (United States)

    Liotta, Marcello; Rizzo, Andrea L.; Barnes, Jaime D.; D'Auria, Luca; Martelli, Mauro; Bobrowski, Nicole; Wittmer, Julian

    2017-04-01

    Among the magmatic volatiles, chlorine (Cl) is degassed at shallow depths offering the opportunity to investigate the behavior of magmatic degassing close to the surface, and the possible occurrence of chemical and isotopic fractionation related to gas/melt partitioning. However, it is still unclear if the isotopic composition of Cl (δ37Cl) can be used as a proxy of magmatic degassing. In this work, we investigate the concentrations of chlorine and sulfur, and the Cl isotope composition of rocks and plume gases collected at Stromboli volcano, Aeolian Islands, Italy. This volcano was chosen because it is characterized by persistent eruptive activity (i.e., Strombolian explosions) and by the presence of magma at very shallow levels in the conduits. Rocks belonging to the different magmatic series erupted throughout the formation of the volcano have δ37Cl values ranging between - 1.0 and + 0.7‰. The isotopic composition seems independent of the Cl concentration of the rocks, but shows a negative correlation with SiO2 content. Plume gases have a greater isotopic compositional variability than the rocks (- 2.2‰ ≤ δ37Cl ≤ + 1.5‰) and the composition seems related to the level of volcanic activity at Stromboli. Gases collected in 2011-2013 during days of ordinary eruptive activity are characterized by δ37Cl values ranging from + 0.3 to + 1.5‰ and S/Cl molar ratios between 1.4 and 2.2, similar to previous S/Cl measurements performed at Stromboli with other techniques. Plume gases collected in July 2014, in days of high-level eruptive activity preceding the onset of the 2014 effusive eruption, have negative δ37Cl values (- 2.2‰ ≤ δ37Cl ≤ - 0.1‰) and S/Cl between 0.9 and 1.2, which are among the lowest S/Cl values measured at this volcano. The amplitude of the volcanic tremor and the variation in the inclination of very long period (VLP) seismic signal polarization clearly indicate that in July 2014 the intensity and frequency of Strombolian

  20. The isotopic composition of lead in man and the environment in Finland: isotope ratios of lead as indicators of pollutant source

    International Nuclear Information System (INIS)

    Keinonen, M.

    1989-01-01

    The isotopic composition of lead was determined in samples from the Helsinki area: in emission sources (gasoline, incinerator and lead smelter emissions, coal), in sources of intake to man (air, diet), in samples representing long-term deposition (lichen, soil, lake sediments) and in human tissue. The measurements of the isotope ratios 206 Pb/ 204 Pb and 206 Pb/ 207 Pb were done by thermal ionization mass spectrometry after chemical separation of lead by anion exchange and cathodic electrodeposition. The origin of lead in man and the environment in the Helsinki area was evaluated by using the differences in the measured isotope ratios as an indicator. The means of the ratios in gasoline ( 206 Pb/ 207 Pb 1.124+-0.026, 206 Pb/ 204 Pb 17.45+-0.42) and the ratios in other emission sources in Helsinki ( 206 Pb/ 207 Pb 1.149-1.226, 206 Pb/ 204 Pb 17.94-19.24) were significantly different. Lead in air samples from Helsinki (1.123+-0.013) could be attributed to gasoline, as lead in soil near a highway (1.136+-0.003). By contrast, isotope ratios measured in lichen (1.148+-0.006) indicated considerable amounts of lead from sources with higher 206 Pb abundances, evidently industrial sources. The isotope ratios in human liver, lung, and bone ( 206 Pb/ 207 Pb 1.142+-0.015, 1.151+-0.011, and 1.156+-0.013, respectively and 206 Pb/ 204 Pb 17.76+-0.28, 17.91+-0.20, and 17.96+-0.09, respectively) were practically the same and no significant dependence of the isotope ratios on age or concentration of lead was seen. In lake sediment cores a correlation was found between the isotope ratios, lead concentration, and depth. The non-anthropogenic lead of high isotope ratios from bedrock was the major component at depths dated older than 100 years. At the surface of the sediment atmospheric lead prevailed, with ratios similar to those of gasoline, air samples and lichen. In the post-1900 layers, anthropogenic lead made up about 40-60% of the total sedimentary lead

  1. Trophic structure of cold-water coral communities revealed from the analysis of tissue isotopes and fatty acid composition

    NARCIS (Netherlands)

    Van Oevelen, D.; Duineveld, G.; Lavaleye, M.S.S.; Kutti, T.; Soetaert, K.

    2018-01-01

    The trophic structure of cold-water coral reef communities at two contrasting locations, the 800-m deep Belgica Mounds (Irish margin) and the 300-m deep Træna reefs (Norwegian Shelf), was investigated using stable isotope (δ13C and δ15N) and fatty-acid composition analysis. A broad range of

  2. The chromium isotopic composition of an Early to Middle Ordovician marine carbonate platform, eastern Precordillera, San Juan, Argentina

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary; Frei, Robert; Gilleaudeau, Geoffrey Jon

    A broad suite of redox proxy data suggest that despite ocean and atmosphere oxygenation in the late Neoproterozoic, euxinic conditions persisted in the global deep oceans until the at least Ordovician [1,2,3]. Major changes in the sulphur isotopic composition of carbonate associated sulphate and ...

  3. Oxygen-isotopic Compositions of Relict and Host Grains in Chondrules in the Yamato 81020 CO3.0 Chondrite

    Science.gov (United States)

    Kunihiro, Takuya; Rubin, Alan E.; McKeegan, Kevin D.; Wasson, John T.

    2006-01-01

    We report the oxygen-isotope compositions of relict and host olivine grains in six high-FeO porphyritic olivine chondrules in one of the most primitive carbonaceous chondrites, CO3.0 Yamato 81020. Because the relict grains predate the host phenocrysts, microscale in situ analyses of O-isotope compositions can help assess the degree of heterogeneity among chondrule precursors and constrain the nebular processes that caused these isotopic differences. In five of six chondrules studied, the DELTA O-17 (=delta O-17 - 0.52 (raised dot) delta O-18) compositions of host phenocrysts are higher than those in low-FeO relict grains; the one exception is for a chondrule with a moderately high-FeO relict. Both the fayalite compositions as well as the O-isotope data support the view that the low-FeO relict grains formed in a previous generation of low-FeO porphyritic chondrules that were subsequently fragmented. It appears that most low-FeO porphyritic chondrules formed earlier than most high-FeO porphyritic chondrules, although there were probably some low-FeO chondrules that formed during the period when most high-FeO chondrules were forming.

  4. Isotopic composition of nitrate and particulate organic matter in a pristine dam reservoir of western India: Implications for biogeochemical processes

    Digital Repository Service at National Institute of Oceanography (India)

    Bardhan, P.; Naqvi, S.W.A.; Karapurkar, S.G.; Shenoy, D.M.; Kurian, S.; Naik, H.

    Isotopic composition of nitrate (δ15N and δ18O) and particulate organic matter (POM; δ15N and δ13C) were measured in the Tillari Reservoir, located at the foothills of the Western Ghats...

  5. Neodymium isotopic composition and concentration in the western North Atlantic Ocean: Results from the GEOTRACES GA02 section

    NARCIS (Netherlands)

    Lambelet, M.; van de Flierdt, T.; Crocket, K.; Rehkämper, M.; Kreissig, K.; Coles, B.; Rijkenberg, M.J.A.; Gerringa, L.J.A.; de Baar, H.J.W.; Steinfeldt, R.

    2016-01-01

    The neodymium (Nd) isotopic composition of seawater is commonly used as a proxy to study past changes in the thermohaline circulation. The modern database for such reconstructions is however poor and the understanding of the underlying processes is incomplete. Here we present new observational data

  6. Neodymium isotopic composition and concentration in the western North Atlantic Ocean : results from the GEOTRACES GA02 section

    NARCIS (Netherlands)

    Lambelet, Myriam; van de Flierdt, Tina; Crocket, Kirtsty; Rehkämper, Mark; Kreissig, Katharina; Coles, Barry; Rijkenberg, Michaël; Gerringa, Loes J.A.; de Baar, Henricus; Steinfeldt, Reiner

    2016-01-01

    The neodymium (Nd) isotopic composition of seawater is commonly used as a proxy to study past changes in the thermohaline circulation. The modern database for such reconstructions is however poor and the understanding of the underlying processes is incomplete. Here we present new observational data

  7. Oxygen and Magnesium Isotopic Compositions of Asteroidal Materials Returned from Itokawa by the Hayabusa Mission

    Science.gov (United States)

    Yurimoto, H; Abe, M.; Ebihara, M.; Fujimura, A.; Hashizume, K.; Ireland, T. R.; Itoh, S.; Kawaguchi, K.; Kitajima, F.; Mukai, T.; hide

    2011-01-01

    The Hayabusa spacecraft made two touchdowns on the surface of Asteroid 25143 Itokawa on November 20th and 26th, 2005. The Asteroid 25143 Itokawa is classified as an S-type asteroid and inferred to consist of materials similar to ordinary chondrites or primitive achondrites [1]. Near-infrared spectroscopy by the Hayabusa spacecraft proposed that the surface of this body has an olivine-rich mineral assemblage potentially similar to that of LL5 or LL6 chondrites with different degrees of space weathering [2]. The spacecraft made the reentry into the Earth s atmosphere on June 12th, 2010 and the sample capsule was successfully recovered in Australia on June 13th, 2010. Although the sample collection processes on the Itokawa surface had not been made by the designed operations, more than 1,500 grains were identified as rocky particles in the sample curation facility of JAXA, and most of them were judged to be of extraterrestrial origin, and definitely from Asteroid Itokawa on November 17th, 2010 [3]. Although their sizes are mostly less than 10 microns, some larger grains of about 100 microns or larger were also included. The mineral assembly is olivine, pyroxene, plagioclase, iron sulfide and iron metal. The mean mineral compositions are consistent with the results of near-infrared spectroscopy from Hayabusa spacecraft [2], but the variations suggest that the petrologic type may be smaller than the spectroscopic results. Several tens of grains of relatively large sizes among the 1,500 grains will be selected by the Hayabusa sample curation team for preliminary examination [4]. Each grain will be subjected to one set of preliminary examinations, i.e., micro-tomography, XRD, XRF, TEM, SEM, EPMA and SIMS in this sequence. The preliminary examination will start from the last week of January 2011. Therefore, samples for isotope analyses in this study will start from the last week of February 2011. By the time of the LPSC meeting we will have measured the oxygen and

  8. Dietary composition and nutrient content of the New Nordic Diet

    DEFF Research Database (Denmark)

    Mithril, Charlotte; Dragsted, Lars Ove; Meyer, Claus

    2013-01-01

    Objective To describe the dietary composition of the New Nordic Diet (NND) and to compare it with the Nordic Nutrition Recommendations (NNR)/Danish Food-based Dietary Guidelines (DFDG) and with the average Danish diet. Design Dietary components with clear health-promoting properties included......), fresh herbs, potatoes, plants and mushrooms from the wild countryside, whole grains, nuts, fish and shellfish, seaweed, free-range livestock (including pigs and poultry) and game. Overall, the average daily intakes of macro- and micronutrients in the NND meet the NNR with small adjustments based...... in the DFDG were included in the NND in amounts at least equivalent to those prescribed by the DFDG. The quantities of the other dietary components in the NND were based on scientific arguments for their potential health-promoting properties together with considerations of acceptability, toxicological...

  9. The using of protons beam for the studying of the homogeneity, elemental and isotopic content of diamond films formed by CVD method

    International Nuclear Information System (INIS)

    Levenets, V.V.; Shchur, A.O.; Strel'nitskij, V.E.; Dudnik, S.A.

    2011-01-01

    The nuclear-physical methods of analysis using the proton beams - PIXE and PIGE –were applied to the studying the features of the diamond films formed by the CVD method on the silicon backing. The reactions of radioactive capture of proton on isotopes 12 C .and 13 C with resonances in cross-sections at 457 and 550 keV were used for determination of the thickness, homogeneity and isotopic content of the diamond films. The proton induced characteristic X-ray of atoms and momentum γ-ray from nuclear reactions were applied to study the impurities content of matter of films. It was shown that the developed technique provides to obtain the diamond layers by thickness up to some microns with high homogeneity on the depth. The ratio of isotopic content 12 C / 13 C was calculated using the measured intensity of γ-ray with energy 2365 keV from reaction 12 C(p, γ) 13 N and 8061 keV from 13 C(p,γ) 14 N. It was shown that the carbon isotopic content was changed from sample to sample. The applied methods of analysis, based on the using of the protons beams from electrostatic accelerators with variation of energy and current of beam, allow to make the non-destructive, local, express analysis of elemental, and in some fa