WorldWideScience

Sample records for carbon isotope ratios

  1. How the oxygen isotope ratio of rain water influences the isotope ratio of chicken eggshell carbonate

    Science.gov (United States)

    Price, Gregory; Grimes, Stephen

    2015-04-01

    The stable oxygen isotope ratio of chicken eggshell carbonate was analysed from chicken eggs laid under free range, and organic farming regimes from across the UK. The eggshell carbonate oxygen isotope data shows a clear depletion in delta18O distribution from the southwest to the northeast. Although consistently offset by around 1 permil, the same isotopic distribution as that seen in eggshell carbonate is observed in the delta18O ratio of rainfall and groundwater from across the UK. This distribution is related to the Rayleigh distillation of rainfall driven by westerly winds across the UK landmass. The clear relationship observed between eggshell delta18O values and that of rainwater presumably reflects the nature of free range chickens which must be drinking locally derived rainwater and supplementing their diet and water intake with locally derived food. These results suggest that the oxygen isotope value of chicken eggshells can be used as a forensic tool to identify the locality that free range and organic eggs were laid within the UK. Furthermore, if suitable material is preserved in the archaeological and geological record then such a relationship can potentially be used to establish the oxygen isotope value of rainwater from which ancient and / or ancestral birds lived.

  2. Carbon abundances and isotope ratios in 70 bright M giants

    International Nuclear Information System (INIS)

    Approximate carbon abundances and 12C/13C isotope ratios are obtained for 70 M giant stars from intermediate-resolution spectrophotometry of the CO bands near 2.3 μm. A low mean carbon abundance ([C/H]=-0.64±0.29) is obtained, suggesting that standard mixing is insufficient to explain atmospheric abundances in M giants. HR 8795 appears to be exceptionally carbon deficient, and is worthy of further study as a possible weak G-band star descendant. (author)

  3. Carbon abundances and isotope ratios in 70 bright M giants

    Energy Technology Data Exchange (ETDEWEB)

    Lazaro, C. (Inst. de Astrofisica de Canarias, Tenerife (Spain)); Lynas-Gray, A.E. (University Coll., London (UK). Dept. of Physics and Astronomy); Clegg, R.E.S. (Royal Greenwich Observatory, Cambridge (UK)); Mountain, C.M.; Zadrozny, A. (Imperial Coll. of Science and Technology, London (UK))

    1991-03-01

    Approximate carbon abundances and {sup 12}C/{sup 13}C isotope ratios are obtained for 70 M giant stars from intermediate-resolution spectrophotometry of the CO bands near 2.3 {mu}m. A low mean carbon abundance ((C/H)=-0.64+-0.29) is obtained, suggesting that standard mixing is insufficient to explain atmospheric abundances in M giants. HR 8795 appears to be exceptionally carbon deficient, and is worthy of further study as a possible weak G-band star descendant. (author).

  4. The use of carbon stable isotope ratios in drugs characterization

    Science.gov (United States)

    Magdas, D. A.; Cristea, G.; Bot, A.; Mirel, V.

    2013-11-01

    Isotopic Ratio Mass Spectrometry (IRMS) is an effective toll to be used for drug product authentication. The isotopic composition could be used to assist in the differentiation between batches of drugs and assist in the identification of counterfeit materials on the market. Only two factors affect the isotopic ratios in pharmaceutical components: the isotopic composition of the raw materials and the synthetic processes performed upon them. Counterfeiting of pharmaceutical drugs threatens consumer confidence in drug products companies' economical well-being. In this preliminary study, the analyzed samples consist in two types of commercially available analgesics, which were purchases from Romanian pharmacies. Differences in δ13C between batches from -29.7 to -31.6% were observed, demonstrating that this method can be used to differentiate among individual drug batches and subsequently identify counterfeits on the market. On the other hand, carbon isotopic ratios differences among producers were recorded, the variations being between -31.3 to -34.9% for the same type of analgesic, but from different manufactures.

  5. The use of carbon stable isotope ratios in drugs characterization

    Energy Technology Data Exchange (ETDEWEB)

    Magdas, D. A., E-mail: gabriela.cristea@itim-cj.ro; Cristea, G., E-mail: gabriela.cristea@itim-cj.ro; Bot, A., E-mail: gabriela.cristea@itim-cj.ro; Mirel, V., E-mail: gabriela.cristea@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca (Romania)

    2013-11-13

    Isotopic Ratio Mass Spectrometry (IRMS) is an effective toll to be used for drug product authentication. The isotopic composition could be used to assist in the differentiation between batches of drugs and assist in the identification of counterfeit materials on the market. Only two factors affect the isotopic ratios in pharmaceutical components: the isotopic composition of the raw materials and the synthetic processes performed upon them. Counterfeiting of pharmaceutical drugs threatens consumer confidence in drug products companies' economical well-being. In this preliminary study, the analyzed samples consist in two types of commercially available analgesics, which were purchases from Romanian pharmacies. Differences in δ{sup 13}C between batches from −29.7 to −31.6% were observed, demonstrating that this method can be used to differentiate among individual drug batches and subsequently identify counterfeits on the market. On the other hand, carbon isotopic ratios differences among producers were recorded, the variations being between −31.3 to −34.9% for the same type of analgesic, but from different manufactures.

  6. The use of carbon stable isotope ratios in drugs characterization

    International Nuclear Information System (INIS)

    Isotopic Ratio Mass Spectrometry (IRMS) is an effective toll to be used for drug product authentication. The isotopic composition could be used to assist in the differentiation between batches of drugs and assist in the identification of counterfeit materials on the market. Only two factors affect the isotopic ratios in pharmaceutical components: the isotopic composition of the raw materials and the synthetic processes performed upon them. Counterfeiting of pharmaceutical drugs threatens consumer confidence in drug products companies' economical well-being. In this preliminary study, the analyzed samples consist in two types of commercially available analgesics, which were purchases from Romanian pharmacies. Differences in δ13C between batches from −29.7 to −31.6% were observed, demonstrating that this method can be used to differentiate among individual drug batches and subsequently identify counterfeits on the market. On the other hand, carbon isotopic ratios differences among producers were recorded, the variations being between −31.3 to −34.9% for the same type of analgesic, but from different manufactures

  7. Daily Variation of Isotope Ratios in Mars Atmospheric Carbon Dioxide

    Science.gov (United States)

    Livengood, Timothy A.; Kostiuk, Theodor; Kolasinski, John R.; Hewagama, Tilak; Henning, Wade G.; Sornig, Manuela; Stangier, Tobias; Krause, Pia; Sonnabend, Guido; Mahaffy, Paul R.

    2014-11-01

    The atmosphere of Mars has been shown by ground based high-resolution infrared spectroscopy and in situ measurements with the Phoenix lander and Mars Science Laboratory Curiosity rover to be enriched in C and O heavy isotopes, consistent with preferential loss of light isotopes in eroding Mars’ primordial atmosphere. The relative abundance of heavy isotopes, combined with contemporary measurements of loss rates to be obtained with MAVEN, will enable estimating the primordial atmospheric inventory on Mars. IR spectroscopy of Mars collected in May 2012 as well as in March and May of 2014 from the NASA IRTF has resolved transitions of all three singly-substituted minor isotopologues of carbon dioxide in addition to the normal isotope, enabling remote measurements of all the carbon and oxygen isotope ratios as a function of latitude, longitude, and time of day. Earlier measurements obtained in October 2007 demonstrated that the relative abundance of O-18 increased linearly with increasing surface temperature over a relatively warm early-afternoon temperature range, but did not extend far enough to inspect the effect of late-afternoon cooling. These results imply that isotopically enriched gas is sequestered overnight when surface temperature is minimum and desorbs through the course of the day as temperature increases. Current spectroscopic constants indicate that the peak isotopic enrichment could be significantly greater than what has been measured in situ, apparently due to sampling the atmosphere at different time of day and surface temperature. The observing runs in 2012 and 2014 measured O-18 enrichment at several local times in both morning and afternoon sectors as well as at the subsolar, equatorial, and anti-subsolar latitudes. The two runs in 2014 have additionally observed O-17 and C-13 transitions in the morning sector, from local dawn to noon. These observations include a limited sampling of measurements over Gale Crater, which can be compared with

  8. Carbon isotope ratios and impurities in diamonds from Southern Africa

    Science.gov (United States)

    Kidane, Abiel; Koch-Müller, Monika; Morales, Luiz; Wiedenbeck, Michael; De Wit, Maarten

    2015-04-01

    We are investigating the sources of diamonds from southern Africa by studying both their carbon isotopic composition and chemical impurities. Our samples include macro-sized diamonds from River Ranch kimberlite in Zimbabwe and the Helam and Klipspringer kimberlitic deposits from South Africa, as well as micro-sized diamonds from Klipspringer and Premier kimberlites in South Africa. We have characterized the samples for their structurally bounded nitrogen, hydrogen and platelets defect using a Fourier Transmission Infrared Spectroscopy (FTIR). Using the DiaMap routine, open source software (Howell et al., 2012), IR spectra were deconvulated and quantified for their nitrogen (A, B and D components) and hydrogen contents. High to moderate nitrogen concentrations (1810 to 400 µg/g; 400 to 50 µg/g respectively) were found in diamonds from Klipspringer and Helam. Moderate to low (isotope studies is the development of calibration materials for SIMS carbon isotopic analyses. We have investigated candidate materials both from a polycrystalline synthetic diamond sheet and two natural gem quality diamonds from Juina (Brazil). Electron-based images of the synthetic diamond sheet, obtained using GFZ Potsdam's dual beam FIB instrument, show many diamond grains with diameters greater than 35 µm. SIMS testing of the isotopic homogeneity of the back and front sides of the synthetic sheets reveal similar 13C/12C ratio within a RSD of isotopic analyses of the two natural diamond RMs yield a constant 13C/12C ratio with RSD of better than 0.5 ‰ . Using the natural diamond as calibratrant, a preliminary result on a selected diamond from the four kimberlitic sample suites yields a δ13C in range between -3 to -7 ‰ . Reference: Howell, D., O'Neill, C. J., Grant, K. J., Griffin, W. L., Pearson, N. J., & O'Reilly, S. Y. (2012). μ-FTIR mapping: Distribution of impurities in different types of diamond growth. Diamond and Related Materials, 29, 29-36. doi:10.1016/j.diamond.2012.06.003.

  9. Carbon and Oxygen Isotopic Ratios for Nearby Miras

    Science.gov (United States)

    Hinkle, Kenneth H.; Lebzelter, Thomas; Straniero, Oscar

    2016-07-01

    Carbon and oxygen isotopic ratios are reported for a sample of 46 Mira and SRa-type variable asymptotic giant branch (AGB) stars. Vibration–rotation first and second-overtone CO lines in 1.5–2.5 μm spectra were measured to derive isotopic ratios for 12C/13C, 16O/17O, and 16O/18O. Comparisons with previous measurements for individual stars and with various samples of evolved stars, as available in the extant literature, are discussed. Models for solar composition AGB stars of different initial masses are used to interpret our results. We find that the majority of M-stars have main sequence masses ≤2 M ⊙ and have not experienced sizable third dredge-up (TDU) episodes. The progenitors of the four S-type stars in our sample are slightly more massive. Of the six C-stars in the sample three have clear evidence relating their origin to the occurrence of TDU. Comparisons with O-rich presolar grains from AGB stars that lived before the formation of the solar system reveal variations in the interstellar medium chemical composition. The present generation of low-mass AGB stars, as represented by our sample of long period variables (LPVs), shows a large spread of 16O/17O ratios, similar to that of group 1 presolar grains and in agreement with theoretical expectations for the composition of mass 1.2–2 M ⊙ stars after the first dredge-up. In contrast, the 16O/18O ratios of present-day LPVs are definitely smaller than those of group 1 grains. This is most probably a consequence of the the decrease with time of the 16O/18O ratio in the interstellar medium due to the chemical evolution of the Milky Way. One star in our sample has an O composition similar to that of group 2 presolar grains originating in an AGB star undergoing extra-mixing. This may indicate that the extra-mixing process is hampered at high metallicity, or, equivalently, favored at low metallicity. Similarly to O-rich grains, no star in our sample shows evidence of hot bottom burning, which is expected

  10. The thermal history of char as disclosed by carbon isotope ratios

    DEFF Research Database (Denmark)

    Egsgaard, Helge; Ambus, Per; Ahrenfeldt, Jesper;

    pyrolysis and isotope ratio mass spectrometry. The results demonstrate that the temperature history of the char is reflected in the fine variation of carbon isotopes. The compound classes responsible for the variation were identified. Key words: Isotope ratio, flash pyrolysis, hot gas cleaning...

  11. Source and migration of light hydrocarbons indicated by carbon isotopic ratios

    International Nuclear Information System (INIS)

    Carbon isotopic ratios can distinguish among different sources of methane and can be used to correlate maturity of sediments with the methane. This technique has been applied to several wells and the isotopic values have been used to suggest the sources of the methane and whether the methane migrated into the area. Comparison of the isotopic ratio changes in ethane, propane, and butanes indicated that isotopic fractionation of methane by migration is not a major factor. The significant changes in methane isotopic ratio and the small changes in the isotopic ratios of these heavier hydrocarbons suggest that, although diffusion is not the sole process in migration, the time for migration is moderate

  12. Carbon and oxygen isotopic ratios of carbon dioxide of a stratospheric profile over Japan

    OpenAIRE

    GAMO, Toshitaka; Tsutsumi, Makoto; SAKAI, Hitoshi; NAKAZAWA, Takakiyo; Tanaka, Masayuki; Honda, Hideyuki; Kubo, Haruya; ITOH, Tomizo

    2011-01-01

    Four stratospheric air samples from 19 to 25 km altitudes over Japan were collected by using a balloon-borne cryogenic sampling system to measure the vertical profiles of carbon and oxygen stable isotopic ratios of the lower stratospheric CO2. The δ13C value of the stratospheric CO2 increased with increasing altitude, while the CO2 mixing ratios decreased, in accordance with anthropogenic input of the isotopically light, fuel CO2 into the atmosphere. However, the relationship between δ13C an...

  13. Spatial and Temporal Trends in Stable Carbon and Oxygen Isotope Ratios of Juvenile Winter Flounder

    Science.gov (United States)

    Isotopic ratios of fish otoliths have been used in numerous studies as natural tags or markers to aid the study of connectivity among fish populations. We investigated the use of spatial and temporal changes in the stable carbon and oxygen isotope ratios of otoliths to different...

  14. Carbon and oxygen isotopic ratios for nearby miras

    CERN Document Server

    Hinkle, K H; Straniero, O

    2016-01-01

    C and O isotopic ratios are reported for a sample of 46 Mira and SRa-type variable AGB stars. Vibration-rotation 1st and 2nd overtone CO lines in 1.5 to 2.5 $\\mu$m spectra were measured to derive isotopic ratios for 12C/13C, 16O/17O, and 16O/18O. Comparisons with previous measurements for individual stars and with various samples of evolved stars are discussed. Models for solar composition AGB stars of different initial masses are used to interpret our results. We find that the majority of the M stars had main sequence masses < 2 Msun and have not experienced sizable third dredge-up episodes. The progenitors of the four S-type stars in our sample are slightly more massive. Of the 6 C stars in the sample three have clear evidence relating their origin to the occurrence of the third dredge-up. Comparisons with O-rich presolar grains from AGB stars that lived before the formation of the solar system reveal variations in the interstellar medium chemical composition. The present generation of low-mass AGB stars...

  15. Oxygen-18 Carbon Dioxide Isotope Ratio in Mars Atmosphere

    Science.gov (United States)

    Kostiuk, T.; Livengood, T. A.; Hewagama, T.; Smith, R.; Fast, K. E.; Annen, J.; Sonnabend, G.; Sornig, M.

    2012-09-01

    The determination of isotopic ratios on Mars is important to the study of atmospheric evolution [1]. The relative abundance of isotopes of CO2 provides insight into the loss of Mars' primordial atmosphere. Isotopic ratios also provide markers in the study of geochemistry of Mars meteorites and future returned samples formed in equilibrium with ambient atmosphere, and are probes of biogenic and abiotic chemistry, which differ in isotope fractionation. Due to its lesser gravity and relatively thin residual atmosphere, Mars' atmosphere should be enriched in heavy isotopes [1]. However Viking [2] results indicated an Earth-like singly substituted oxygen-18 CO2 isotopic ratio, 18OCO/OCO, with δ18O = 0±50‰ relative to Vienna Standard Mean Ocean Water (VSMOW). By comparison, isotopic ratios in Earth atmospheric CO2 are not uniquely defined due to seasonal and biotic variability, but have a range 0-41‰ relative to VSMOW [3, 4]. Phoenix lander TEGA [3] measurements found a modest enrichment of δ18O = 31.0±5.7‰. Only the Viking and Phoenix landers have carried a mass spectrometer to Mars, so far, until the arrival of Mars Science Laboratory in August 2012. Using ground-based spectroscopic techniques Krasnopolsky et al. [5] also found modest enrichment δ18O = 18±18‰. We present results from fully resolved spectroscopic measurements near 10.6 μm of both the normal and singly substituted oxygen- 18 CO2 lines, taken with the Goddard Space Flight Center Heterodyne Instrument for Planetary Winds And Composition (HIPWAC) at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii. Measurements with spectral resolving power λ/Δλ=107 were obtained in October 2007 with an instantaneous field-of-view on the planet of ~1 arcsec, at the locations shown in Fig. 1 as open squares. The solid and broken line tracks show Mars SPICAM measurements of ozone corresponding to ozone measurements also obtained with HIPWAC and shown as hatched and solid regions [6]. Figure 1

  16. On the isotope ratio of hydrogen, oxygen, carbon, nitrogen, and sulfur in man

    International Nuclear Information System (INIS)

    Experimental investigations of the isotope ratio of hydrogen, oxygen, carbon, nitrogen and sulfur in urine of persons living at different locations show considerable variations. A distinct relation to the isotope ratio of the local drinking water has only been observed in the case of hydrogen. The variations are far from being within the experimental limits of error. Therefore, they are decisive in selecting the relative abundance of the labelling isotope in tracer experiments on human metabolism. (author)

  17. Continuous flow isotope ratio mass spectrometry of carbon dioxide trapped as strontium carbonate

    International Nuclear Information System (INIS)

    The isotopic signal provided by differential discrimination against atmospheric carbon dioxide (13CO2) by C3 and C4 plant photosynthetic pathways is being widely used to study the processes of carbon (C) fixation, soil organic matter formation, and mineralization in nature. These studies have been facilitated by the availability of automated C and nitrogen (N) combustion analyzers (ANCA) combined with continuous flow isotope ratio mass spectrometers (CFIRMS). Analysis of 13CO2 in these instruments requires consistent sample mass for best precision, a requirement that is easily satisfied for soil and tissue samples by adjusting sample weight. Consistent CO2 sample size is much more difficult to achieve using gas handling systems for samples of headspace gases when CO2 concentrations vary widely. Long storage of gaseous samples also is difficult. Extended respiration studies are most easily conducted by trapping CO2 in alkali and conversion to an insoluble carbonate. Thermal decomposition of the carbonate in an on-line ANCA allows consistent and optimal CO2 sample mass to be obtained. The use of precipitated carbonates also facilitates storage of samples and enables full automation of sample analysis using an ANCA interfaced to a CFIRMS. Calcium (Ca), strontium (Sr), and barium (Ba) carbonates were tested. Strontium carbonate (SrCO3) with the addition of vanadium pentoxide (V2O5) as a combustion catalyst was found most suitable

  18. An analytical system for stable isotope analysis on carbon monoxide using continuous-flow isotope-ratio mass spectrometry

    NARCIS (Netherlands)

    Pathirana, S. L.; Van Der Veen, C.; Popa, M. E.; Röckmann, T.

    2015-01-01

    A fully automated system for the determination of δ13C and δ18O in atmospheric CO has been developed. CO is extracted from an air sample and converted into carbon dioxide (CO2) using the Schütze reagent. The isotopic composition is determined with an isotope-ratio mass spectrometer (IRMS) technique.

  19. Stable carbon isotope ratios of ambient secondary organic aerosols in Toronto

    Science.gov (United States)

    Saccon, M.; Kornilova, A.; Huang, L.; Moukhtar, S.; Rudolph, J.

    2015-09-01

    A method to quantify concentrations and stable carbon isotope ratios of secondary organic aerosols has been applied to study atmospheric nitrophenols in Toronto, Canada. The sampling of five nitrophenols, all with substantial secondary formation from the photooxidation of aromatic volatile organic compounds (VOCs), was conducted in the gas phase and particulate matter (PM) together and in PM alone. Their concentrations in the atmosphere are in the low ng m-3 range and, consequently, a large volume of air (> 1000 m3) is needed to analyze samples for stable carbon isotope ratios, resulting in sampling periods of typically 24 h. While this extended sampling period increases the representativeness of average values, it at the same time reduces possibilities to identify meteorological conditions or atmospheric pollution levels determining nitrophenol concentrations and isotope ratios. Average measured carbon isotope ratios of the different nitrophenols are between -34 and -33 ‰, which is well within the range predicted by mass balance. However, the observed carbon isotope ratios cover a range of nearly 9 ‰ and approximately 20 % of the isotope ratios of the products have isotope ratios lower than predicted from the kinetic isotope effect of the first step of the reaction mechanism and the isotope ratio of the precursor. This can be explained by isotope fractionation during reaction steps following the initial reaction of the precursor VOCs with the OH radical. Limited evidence for local production of nitrophenols is observed since sampling was done in the Toronto area, an urban center with significant anthropogenic emission sources. Strong evidence for significant local formation of nitrophenols is only found for samples collected in summer. On average, the difference in carbon isotope ratios between nitrophenols in the particle phase and in the gas phase is insignificant, but for a limited number of observations in summer, a substantial difference is observed. This

  20. Online stable carbon isotope ratio measurement in formic acid, acetic acid, methanol and ethanol in water by high performance liquid chromatography-isotope ratio mass spectrometry

    International Nuclear Information System (INIS)

    A suitable analysis condition was determined for high performance liquid chromatography-isotope ratio mass spectrometry (HPLC-IRMS) while making sequential measurements of stable carbon isotope ratios of δ13C in formic acid, acetic acid, methanol and ethanol dissolved in water. For this online column separation method, organic reagents are not applicable due to carbon contamination; thus, water and KH2PO4 at low concentrations were tested as mobile phase in combination with a HyPURITY AQUASTARTM column. Formic acid, acetic acid, methanol and ethanol were separated when 2 mM KH2PO4 aqueous solution was used. Under the determined analysis condition for HPLC-IRMS, carbon concentrations could be measured quantitatively as well as carbon isotope ratio when carbon concentration was higher than 0.4 mM L for each chemical

  1. Stable carbon isotope ratios of toluene in the boundary layer and the lower free troposphere

    Directory of Open Access Journals (Sweden)

    J. Wintel

    2013-04-01

    Full Text Available Measurements of stable carbon isotope ratios in VOC are a powerful tool to identify sources or to track both dynamical and chemical processes. During the field campaign ZEPTER-2 in autumn 2008 whole air samples were collected on board a Zeppelin NT airship in the planetary boundary layer and the lower free troposphere over south-west Germany. These samples were analysed with respect to VOC mixing ratios and stable carbon isotope ratios using a gas chromatograph combustion isotope ratio mass spectrometer. In this study we present the results for toluene, one of the major anthropogenic pollutants. In the boundary layer we observed rather fresh emissions mixing into the background and derived a toluene source isotope ratio of δ13C = −28.2 ± 0.5 ‰. Using the concept of the effective kinetic isotope effect, we were able to separate the effects of dilution processes and photochemical degradation in the free troposphere. We estimated the photochemical age of toluene in the atmosphere in two different ways (using isotope ratios and mixing ratios, respectively. The results differ strongly in the planetary boundary layer, probably due to mixing processes, but are compatible with each other in the free troposphere.

  2. Stable Carbon Isotope Ratios of Phenolic Compounds in Secondary Particulate Organic Matter Formed by Photooxidation of Toluene

    CERN Document Server

    Irei, Satoshi; Huang, Lin; Auld, Janeen; Collin, Fabrice; Hastie, Donald

    2014-01-01

    Compound-specific stable carbon isotope ratios for phenolic compounds in secondary particulate organic matter (POM) formed by photooxidation of toluene were studied. Secondary POM generated by photooxidation of toluene using a continuous-flow reactor and an 8 cubic meter indoor smog chamber was collected, and then extracted with acetonitrile. Eight phenolic compounds were identified in the extracts by a gas chromatograph coupled with a mass spectrometer, and their compound-specific stable carbon isotope ratios were determined by a gas chromatograph coupled with a combustion furnace followed by an isotope ratio mass spectrometer. The majority of the products, including methylnitrophenols and methylnitrocatechols, were isotopically depleted by 5 to 6 permil compared to the initial isotope ratio for toluene, whereas the isotope ratio for 4_nitrophenol remained the same as the initial isotope ratio for toluene. Based on the reaction mechanisms postulated in literature, stable carbon isotope ratios of these produc...

  3. Method for the determination of concentration and stable carbon isotope ratios of atmospheric phenols

    Directory of Open Access Journals (Sweden)

    M. Saccon

    2013-05-01

    Full Text Available A method for the determination of the stable carbon isotopic composition of atmospheric nitrophenols in the gas and particulate phases is presented. It has been proposed to use the combination of concentration and isotope ratio measurements of precursor and product to test the applicability of results of laboratory studies to the atmosphere. Nitrophenols are suspected to be secondary products formed specifically from the photooxidation of volatile organic compounds. XAD-4™ resin was used as an adsorbent on quartz filters to sample ambient phenols using conventional high-volume air samplers at York University in Toronto, Canada. Filters were extracted in acetonitrile, with a HPLC clean-up step and a solid phase extraction step prior to derivatization with BSTFA. Concentration measurements were done with gas chromatography-mass spectrometry and gas chromatography-isotope ratio mass spectrometry was used for isotope ratio analysis. The technique presented allows for atmospheric compound-specific isotopic composition measurements for five semi-volatile phenols with an estimated accuracy of 0.3‰ to 0.5‰ at atmospheric concentrations exceeding 0.1 ng m−3 while the detection limits for concentration measurements are in the pg m−3 range. Isotopic fractionation throughout the entire extraction procedure and analysis was proven to be below the precision of the isotope ratio measurements. The method was tested by conducting ambient measurements from September to December 2011.

  4. Tracing the decomposition of dissolved organic carbon in artificial recharge by carbon isotope ratios

    International Nuclear Information System (INIS)

    One of the challenges in artificial recharge for drinking water purposes is to decrease the relatively high content of dissolved organic carbon (DOC) in surface waters. Two processes have been suggested to have an effect on diminishing the concentrations of DOC in infiltrated water during artificial recharge: 1) Either organic matter is adsorbed on the surfaces of soil particles, or 2) DOC is oxidized and decomposed by bacterially mediated processes. Geochemical concentration and microbiological activity data have, however, proved to be insufficient for getting quantitative evidence for comparison of these models. We applied the isotopic composition of dissolved inorganic carbon (DIC) in the recharged water as a tracer for redox processes and decomposition of DOC. The study site is an artificial groundwater plant at Janiksenlinna in southern Finland. Surface water is artificially recharged into an unconfined shallow aquifer by pond infiltration. Infiltrated surface water is derived from Lake Paijanne, a large lake in middle Finland. Water samples were collected from infiltrated surface water and groundwater at varying distances from the infiltration plant. The samples were analysed for the contents of the major dissolved components, DOC and the isotopic composition of carbon in DIC. In addition, the 18O/16O and D/H ratios of water were determined in order to calculate mixing ratios between local groundwater and infiltrated surface water. The δ18O and δD end member compositions for mixing calculations were based on a monitoring period of two years. The δ13CDIC value in recharge waters was -10.4 per mille, which differed significantly from the composition of local groundwaters, with δ13CDIC at -20.8 per mille. The recharged water recorded a considerable decrease in δ13CDIC from -10.4 per mille in the pond to -16.3 per mille in the first observation well, at a distance of 30 metres. No admixture of local groundwater was observed in this well based on oxygen and

  5. Tracing the decomposition of dissolved organic carbon in artificial recharge by carbon isotope ratios

    International Nuclear Information System (INIS)

    One of the challenges in artificial recharge for drinking water purposes is to decrease the relatively high content of dissolved organic carbon (DOC) in surface waters. Two processes have been suggested to have an effect on diminishing the concentrations of DOC in infiltrated water during artificial recharge: 1) Either organic matter is adsorbed on the surfaces of soil particles, or 2) DOC is oxidized and decomposed by bacterially mediated processes. Geochemical concentration and microbiological activity data have, however, proved to be insufficient for getting quantitative evidence for comparison of these models. We applied the isotopic composition of dissolved inorganic carbon (DIC) in the recharged water as a tracer for redox processes and decomposition of DOC. The study site is an artificial groundwater plant at Janiksenlinna in southern Finland. Surface water is artificially recharged into an unconfined shallow aquifer by pond infiltration. Infiltrated surface water is derived from Lake Paijanne, a large lake in middle Finland. Water samples were collected from infiltrated surface water and groundwater at varying distances from the infiltration plant. The samples were analysed for the contents of the major dissolved components, DOC and the isotopic composition of carbon in DIC. In addition, the δ18O/16O and D/H ratios of water were determined in order to calculate mixing ratios between local groundwater and infiltrated surface water. The 18O and δD end member compositions for mixing calculations were based on a monitoring period of two years. The δ13CDIC value in recharge waters was -10.4 per mille, which differed significantly from the composition of local groundwaters, with δ13CDIC at -20.8 per mille. The recharged water recorded a considerable decrease in δ13CDIC from -10.4 per mille in the pond to -16.3 per mille in the first observation well, at a distance of 30 metres. No admixture of local groundwater was observed in this well based on oxygen and

  6. Carbon isotope ratios and isotopic correlations between components in fruit juices

    Science.gov (United States)

    Wierzchnicki, Ryszard

    2013-04-01

    Nowadays food products are defined by geographical origin, method of production and by some regulations concerning terms of their authenticity. Important data for confirm the authenticity of product are providing by isotopic methods of food control. The method checks crucial criteria which characterize the authenticity of inspected product. The European Union Regulations clearly show the tendency for application of the isotopic methods for food authenticity control (wine, honey, juice). The aim of the legislation steps is the protection of European market from possibility of the commercial frauds. Method of isotope ratio mass spectrometry is very effective tool for the use distinguishably the food products of various geographical origin. The basic problem for identification of the sample origin is the lack of databases of isotopic composition of components and information about the correlations of the data. The subject of the work was study the isotopic correlations existing between components of fruits. The chemical and instrumental methods of separation: water, sugars, organic acids and pulp from fruit were implemented. IRMS technique was used to measure isotopic composition of samples. The final results for original samples of fruits (apple, strawberry etc.) will be presented and discussed. Acknowledgement: This work was supported by the Polish Ministry of Science and Higher Education under grant NR12-0043-10/2010.

  7. Assessment of primary production in a eutrophic lake from carbon and nitrogen isotope ratios of a carnivorous fish

    International Nuclear Information System (INIS)

    The carbon and nitrogen isotope ratios of Hypomesus transpacificus (a pond smelt) in a eutrophic lake, Lake Suwa, were measured from April to September in 1986 and 1987. The differences in the isotope ratios between these two years were observed. The stable isotopes were transferred from phytoplankton to zooplankton and pond smelt, associated with organic matters. Therefore, the difference in the isotope ratios in two years seemed to reflect the differences of the proceeding of primary production. It was suggested that the carbon and nitrogen isotope ratios of animal, whose trophic level is far from primary producer, can be the qualitative indicators for assessing the primary production in a lake ecosystem. (author)

  8. Stable carbon isotope ratios as proxies for CO2 migration: An experimental approach with analogue fluids

    Science.gov (United States)

    Myrttinen, A.; Becker, V.; Mayer, B.; Barth, J. A.

    2012-12-01

    Stable carbon isotope ratios have proven to be highly sensitive tracers of CO2 migration in the subsurface, provided that the δ13C value of injected CO2 is distinct from that of baseline carbon in the reservoir and in shallow aquifers. This is of great importance for tracing the movement and the fate of injected CO2 in storage reservoirs where fluid and gas samples for chemical and isotope analyses can be obtained. One fundamental aspect that needs to be considered is carbon isotope fractionation between the various dissolved inorganic carbon (DIC) species and sub- or super-critical CO2. Such isotope fractionation may occur at various stages of CO2 migration including, the initial stages of injection during CO2 dissolution; during possible CO2 desiccation in pores; during CO2 migration within the reservoir or even during potential leakage into the near-surface environment. The magnitude and direction of carbon isotope fractionation (1000lnαDIC-CO2) between the DIC species and the injected CO2 depends highly on temperature and pH. At shallow depths, where temperatures are moderate and pH values are typically close to neutral, HCO3- is the dominant form of DIC. Carbon isotope fractionation between CO2 and DIC is therefore expected to reach ~ +10 ‰, resulting in a more positive δ13C value of DIC compared to that of the injected CO2. On the other hand, during injection, elevated temperatures and pH values of below 6 are usually observed. Here, H2CO3 is the dominant form of DIC and carbon isotope fractionation of close to -1 ‰ is expected. However, literature data on isotope fractionation values between H2CO3 and CO2 at temperatures above ˜ 60 °C are limited. In order to investigate the effects of pH and temperature on carbon isotope fractionation at various subsurface conditions, including elevated temperatures and pressures typical for CO2 reservoirs, laboratory experiments with analogue fluids were conducted within the framework of the CO2ISO-LABEL project

  9. Tunable Diode Laser Measurements of Leaf-scale Carbon Isotope Discrimination and Ecosystem Respired Carbon and Oxygen Isotope Ratios in a Semi-arid Woodland

    Science.gov (United States)

    McDowell, N.; Chris, B.; Hanson, D.; Kern, S.; Meyer, C.; Pockman, W.; Powers, H.

    2005-12-01

    We present results and speculative interpretation of leaf-level carbon isotope discrimination and ecosystem respired carbon and oxygen isotope ratios from a semi-arid, C3/C4 woodland located in northern New Mexico, USA. Overstory leaf area index (LAI) is dominated by live juniper (Juniperus monosperma) trees with an LAI value of approximately 1.0 m2 per m2 ground area, and has a seasonally dynamic understory of mixed C3 forbs and C4 grasses and cacti, with a maximum LAI of 0.30 m2 per m2 ground area. Ecosystem respired carbon isotope ratios showed values characteristic of C3 dominated photosynthesis (Keeling plot intercepts of -35 to -22 per mil). Seasonal variation was typical of that found in wetter, C3 dominated forests, as was the dependence on climate (e.g. relationships with vapor pressure deficit, soil water content, and canopy conductance). Leaf-level carbon isotope discrimination of the junipers, measured by coupling a Li-Cor 6400 photosynthesis system to the TDL, provided discrimination-Ci and discrimination-vpd relationships consistent with measured ecosystem respired carbon isotope ratios. The oxygen isotope ratio of ecosystem respiration was dependent on rain water isotope composition, but was correlated with soil water content during rain-free periods. The cumulative effect of vapor pressure deficit after a rain event was tightly correlated with the oxygen isotope ratio of ecosystem respiration, suggesting the primary drivers are evaporative enrichment of soil water and perhaps nocturnal leaf enrichment. Instrument precision for carbon and oxygen isotope ratios of carbon dioxide is 0.06 to 0.18 per mil; however, overall precision is somewhat lower due to pressure and sampling effects.

  10. Towards a better understanding of magnesium-isotope ratios from marine skeletal carbonates

    Science.gov (United States)

    Hippler, Dorothee; Buhl, Dieter; Witbaard, Rob; Richter, Detlev K.; Immenhauser, Adrian

    2009-10-01

    This study presents magnesium stable-isotope compositions of various biogenic carbonates of several marine calcifying organisms and an algae species, seawater samples collected from the western Dutch Wadden Sea, and reference materials. The aim of this study is to explore the influence of mineralogy, taxonomy and environmental factors (e.g., seawater isotopic composition, temperature, salinity) on magnesium-isotopic (δ 26Mg) ratios of skeletal carbonates. Using high-precision multi-collector inductively coupled plasma mass spectrometry, we observed that the magnesium-isotopic composition of seawater from the semi-enclosed Dutch Wadden Sea is identical to that of open marine seawater. We further found that a considerable component of the observed variability in δ 26Mg values of marine skeletal carbonates can be attributed to differences in mineralogy. Furthermore, magnesium-isotope fractionation is species-dependent, with all skeletal carbonates being isotopically lighter than seawater. While δ 26Mg values of skeletal aragonite and high-magnesium calcite of coralline red algae indicate the absence or negligibility of metabolic influences, the δ 26Mg values of echinoids, brachiopods and bivalves likely result from a taxon-specific level of control on Mg-isotope incorporation during biocalcification. Moreover, no resolvable salinity and temperature effect were observed for coralline red algae and echinoids. In contrast, Mg-isotope data of bivalves yield ambiguous results, which require further validation. The data presented here, point to a limited use of Mg isotopes as temperature proxy, but highlight the method's potential as tracer of seawater chemistry through Earth's history.

  11. Method for determination of stable carbon isotope ratio of methylnitrophenols in atmospheric PM

    Directory of Open Access Journals (Sweden)

    S. Moukhtar

    2011-05-01

    Full Text Available A technique for the measurement of the stable isotope ratio of methylnitrophenols in atmospheric particulate matter (PM is presented. It has been found in numerous laboratory studies that these compounds are photooxidation products of toluene in PM. Atmospheric samples from rural and suburban areas were collected for evaluation of the procedure. PM was collected on quartz fibre filters using dichotomous high volume air samplers for PM 2.5. Methylnitrophenols were extracted from the filters using acetonitrile. The sample was then purified using a combination of high-performance liquid chromatography (HPLC and solid phase extraction (SPE. The final solution was then divided into two aliquots. To one aliquot, a derivatising agent, Bis(trimethylsilyltrifluoroacetamide (BSTFA, was added to the solution for Gas Chromatography/Mass Spectroscopy (GC/MS analysis. The second half of the sample was stored at low temperature. When GC/MS analysis showed high enough concentrations the remaining sample was derivatized with BSTFA and analysed for stable isotope ratio using a Gas Chromatography/Isotope Ratio Mass Spectrometry (GC-IRMS.

    In all atmospheric PM samples analysed, 2-methyl-4-nitrophenol was found to be the most abundant methylnitrophenol. Nevertheless, due to low pollution levels occurring in the rural area, no samples had concentrations high enough to perform stable carbon isotope composition measurements of the methylnitrophenols. Samples collected in the suburban area could be analysed for carbon stable isotope ratio using GC-IRMS.

    The procedure described in this paper provides a very sensitive and selective method for the analysis of methylnitrophenols in atmospheric PM at concentrations as low as 1 pg m−3. For accurate (within ±0.5‰ stable isotope ratio analysis significantly higher concentrations in the range of 100 pg m−3 or more are required.

  12. An analytical system for stable isotope analysis on carbon monoxide using continuous-flow isotope-ratio mass spectrometry

    OpenAIRE

    S. L. Pathirana; C. van der Veen; Popa, M. E.; T. Röckmann

    2015-01-01

    A fully automated system for the determination of δ13C and δ18O in atmospheric CO has been developed. CO is extracted from an air sample and converted into carbon dioxide (CO2) using the Schütze reagent. The isotopic composition is determined with an isotope-ratio mass spectrometer (IRMS) technique. The entire system is continuously flushed with high-purity helium (He), the carrier gas. The blank signal of the Schütze reagent is ~ 4 nmol mol−1, or 1–3 % of the typical sam...

  13. Postmortem study of stable carbon isotope ratios in human cerebellar DNA: preliminary results

    International Nuclear Information System (INIS)

    It is observed that 13C/12C ratios in tissue specimens removed postmortem in the United States and Canada are significantly different from corresponding ratios in European specimens. On the basis of this information, measurements of carbon isotope ratios in DNA isolated from cerebella of native-born and European-born North Americans are in progress with the goal of estimating the average lifetime rate of DNA turnover in human neurons. Preliminary results from twenty postmortem examinations are consistent with the hypothesis that a significant proportion of human cerebellar DNA is renewed during the lifetime of an individual

  14. Comparison of gas chromatography/isotope ratio mass spectrometry and liquid chromatography/isotope ratio mass spectrometry for carbon stable-isotope analysis of carbohydrates

    OpenAIRE

    Moerdijk-Poortvliet, T.C.W.; Schierbeek, H.; Houtekamer, M; Engeland, T.; D. Derrien; Stal, L.J.; Boschker, H.T.S.

    2015-01-01

    We compared gas chromatography/isotope ratio mass spectrometry (GC/IRMS) and liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) for the measurement of d13C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported

  15. The Kranz syndrome in the Eragrostideae (Chloridoideae, Poaceae) as indicated by carbon isotopic ratios*

    OpenAIRE

    Hector O. Panarello; Evangelina Sanchez

    1984-01-01

    13C/12C ratios are generally regarded as being very reliable indicators of C3 or C4 photosynthesis. These relative carbon isotope ratios are expressed as a negative δ 3C and fall into two distinct groups: Kranz (or C4) plants with δ between -9°/00 no and -18°/00 and non-Kranz (C3) plants with δ between -22°/00 and -280/00 no. In this paper, 29 taxa, representing 12 genera, of the tribe Eragrostideae were examined by mass spectrometry for their δ 13C in dried leaf tissue. All these taxa prove...

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

    Science.gov (United States)

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

    2016-09-01

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

  17. Stable carbon isotope ratios of intact GDGTs indicate heterogeneous sources to marine sediments

    Science.gov (United States)

    Pearson, Ann; Hurley, Sarah J.; Walter, Sunita R. Shah; Kusch, Stephanie; Lichtin, Samantha; Zhang, Yi Ge

    2016-05-01

    Thaumarchaeota, the major sources of marine glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), are believed to fix the majority of their carbon directly from dissolved inorganic carbon (DIC). The δ13C values of GDGTs (δ13CGDGT) may be powerful tools for reconstructing variations in the ocean carbon cycle, including paleoproductivity and water mass circulation, if they can be related to values of δ13CDIC. To date, isotope measurements primarily are made on the C40 biphytane skeletons of GDGTs, rather than on complete tetraether structures. This approach erases information revealed by the isotopic heterogeneity of GDGTs within a sample and may impart an isotopic fractionation associated with the ether cleavage. To circumvent these issues, we present δ13C values for GDGTs from twelve recent sediments representing ten continental margin locations. Samples are purified by orthogonal dimensions of HPLC, followed by measurement of δ13C values by Spooling Wire Microcombustion (SWiM)-isotope ratio mass spectrometry (IRMS) with 1σ precision and accuracy of ±0.25‰. Using this approach, we confirm that GDGTs, generally around -19‰, are isotopically "heavy" compared to other marine lipids. However, measured δ13CGDGT values are inconsistent with predicted values based on the 13C content of DIC in the overlying water column and the previously-published biosynthetic isotope fractionation for a pure culture of an autotrophic marine thaumarchaeon. In some sediments, the isotopic composition of individual GDGTs differs, indicating multiple source inputs. The data appear to confirm that crenarchaeol primarily is a biomarker for Thaumarchaeota, but its δ13C values still cannot be explained solely by autotrophic carbon fixation. Overall the complexity of the results suggests that both organic carbon assimilation (ca. 25% of total carbon) and multiple source(s) of exogenous GDGTs (contributing generally <30% of input to sediments) are necessary to explain the observed

  18. Stable Carbon Isotope Ratios for Giant Stars in the Globular Cluster M13

    Science.gov (United States)

    Rhee, Jaehyon; Pilachowski, C. A.

    2013-01-01

    Recently, our paradigm for the formation and evolution of globular clusters has shifted. We now understand that the majority of present-day stars in globular clusters formed as second-generation stars, primarily from the ejecta of first-generation AGB stars, while the majority of first generation, less centrally concentrated stars, have been dynamically lost to the cluster (D'Ercole et al. 2011). This paradigm explains the observed star-to-star variations in the abundances of light element observed in globular clusters, and suggests that the carbon isotope ratio should be similarly differentiated between first and second generation stars. In an effort to verify this scenario, we have recently utilized the Gemini/NIFS to determine carbon isotope abundances (12C and 13C) for 18 giant stars in the globular clusters M13 through medium-resolution (R ˜ 5300) infrared spectroscopy of the first-overtone CO bands near 2.3 μm. Our program stars are distributed from the tip of the RGB to the BLF (the bump in the luminosity function) of M13, and their Na, Mg, and Al abundances are already known from homogeneous data set analysis. Therefore, adding reliable abundances of the stable carbon isotopes to this homogeneous spectroscopic sample permits systematic tests of cluster chemical evolution models. We report preliminary results of the carbon abundance analysis for our NIFS K-band spectra and present an overview of our ongoing effort with other globular clusters.

  19. Carbon isotope ratios in assessing the origin of water in dam leakage problems

    International Nuclear Information System (INIS)

    The investigation of the origin and dynamics of groundwater in the vicinity of dams and reservoirs is a major concern of the responsible authorities in case of important leakage problems. In most cases, local groundwater and water related tot he leakage emerge downstream of the dam with a complex mixing pattern. The proper characterization of the flow rate and flow patterns of water derived from the reservoir requires the use of several hydrological techniques, including environmental isotopes and artificial tracers. Among the common isotope tools, oxygen-18 deuterium and tritium are routinely used. The different origin of surface waters stored in the reservoir, and local groundwaters, usually derived from local recharge, result in distinct isotope signatures, allowing a proper characterization of each water type. However, practical work in investigating this type of problems under different geographic and climatic conditions has shown that in many cases, hydrochemistry and these isotopes do not provide a convincing and complete evidence about the origin and mixing patterns of the two types of waters. The proximity of the recharge areas and the short transit time of local groundwater do not result in significant differences in the chemical and/or isotope contents. 13C/12C ratios in the Total Dissolved Inorganic Carbon (TDIC) has been successfully used to investigate some aspects of leakage problems in several dams located in temperate and tropical climates

  20. Applications of compound-specific carbon isotope ratios in organic contaminant studies

    International Nuclear Information System (INIS)

    In this paper results are presented on the application of compound-specific isotope ratios measurements to assess biodegradation of chlorinated solvents, in particularly on microbial dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE). Analytical aspects and isotope data from laboratory and field studies are discussed. The analytical tests showed that both headspace and SPME techniques provide accurate δ13C values with a similar precision for a wide range of chlorinated solvents. However, the SPME method is generally more sensitive. The microcosm experiments show that a significant isotopic fractionation occurs during dechlorination of PCE and TCE to ethene. The largest fractionation factors are observed in the steps DCE-VC and VC-Ethene. In general, the δ13C of each dechlorination product was always more negative than the δ13C of the corresponding precursor. In addition, the δ13C values of each compound increased with time. A similar pattern was observed for dechlorination of PCE at a field site. These results show that compound-specific carbon isotope ratios technology is a very sensitive tool for evaluation of natural attenuation of chlorinated solvents in groundwater. (author)

  1. Method for determination of stable carbon isotope ratio of methylnitrophenols in atmospheric particulate matter

    Directory of Open Access Journals (Sweden)

    S. Moukhtar

    2011-11-01

    Full Text Available A technique for the measurement of the stable isotope ratio of methylnitrophenols in atmospheric particulate matter is presented. Atmospheric samples from rural and suburban areas were collected for evaluation of the procedure. Particulate matter was collected on quartz fibre filters using dichotomous high volume air samplers. Methylnitrophenols were extracted from the filters using acetonitrile. The sample was then purified using a combination of high-performance liquid chromatography and solid phase extraction. The final solution was then divided into two aliquots. To one aliquot, a derivatising agent, Bis(trimethylsilyltrifluoroacetamide, was added for Gas Chromatography-Mass Spectrometry analysis. The second half of the sample was stored in a refrigerator. For samples with concentrations exceeding 1 ng μl−1, the second half of the sample was used for measurement of stable carbon isotope ratios by Gas Chromatography-Isotope Ratio Mass Spectrometry.

    The procedure described in this paper provides a method for the analysis of methylnitrophenols in atmospheric particulate matter at concentrations as low as 0.3 pg m−3 and for stable isotope ratios with an accuracy of better than ±0.5‰ for concentrations exceeding 100 pg m−3.

    In all atmospheric particulate matter samples analysed, 2-methyl-4-nitrophenol was found to be the most abundant methylnitrophenol, with concentrations ranging from the low pg m−3 range in rural areas to more than 200 pg m−3 in some samples from a suburban location.

  2. A Widely Tunable Infrared Laser Spectrometer for Measurements of Isotopic Ratios of Carbon Cycle Gases

    Energy Technology Data Exchange (ETDEWEB)

    Joanne H. Shorter; J. Barry McManus; David D. Nelson; Charles E. Kolb; Mark S. Zahniser; Ray Bambha; Uwe Lehmann; Tomas Kulp; Stanley C. Tyler

    2005-01-31

    The atmospheric abundances of carbon dioxide and methane have increased dramatically during the industrial era. Measurements of the isotopic composition of these gases can provide a powerful tool for quantifying their sources and sinks. This report describes the development of a portable instrument for isotopic analysis CO{sub 2} and CH{sub 4} using tunable infrared laser absorption spectroscopy. This instrument combines novel optical design and signal processing methods with a widely tunable mid-infrared laser source based on difference frequency generation (DFG) which will can access spectral regions for all the isotopes of CO{sub 2} and CH{sub 4} with a single instrument. The instrument design compensates for the large difference in concentration between major and minor isotopes by measuring them with path lengths which differ by a factor of 100 within the same multipass cell. During Phase I we demonstrated the basic optical design and signal processing by determining {sup 13}CO{sub 2} isotopic ratios with precisions as small as 0.2{per_thousand} using a conventional lead salt diode laser. During Phase II, the DFG laser source was coupled with the optical instrument and was demonstrated to detect {sup 13}CH{sub 4}/{sup 12}CH{sub 4} ratios with a precision of 0.5{per_thousand} and an averaging time of 20 s using concentrated methane in air with a mixing ratio of 2700 ppm. Methods for concentrating ambient air for isotopic analysis using this technique have been evaluated. Extensions of this instrument to other species such as {sup 13}CO{sub 2}, C{sup 18}OO, and CH{sub 3}D are possible by substituting lasers at other wavelengths in the DFG source module. The immediate commercial application of this instrument will be to compete with existing mass spectrometric isotope instruments which are expensive, large and relatively slow. The novel infrared source developed in this project can be applied to the measurement of many other gas species and will have wide

  3. Tracing the decomposition of dissolved organic carbon in artificial groundwater recharge using carbon isotope ratios

    International Nuclear Information System (INIS)

    Reducing the concentration of dissolved organic C (DOC) in water is one of the main challenges in the process of artificial groundwater recharge. At the Tuusula waterworks in southern Finland, surface water is artificially recharged into an esker by pond infiltration and an equal amount of groundwater is daily pumped from the aquifer. This groundwater study was conducted to consider the role of redox processes in the decomposition of DOC. The isotopic composition of dissolved inorganic C (δ 13CDIC) in the recharged water was used as a tracer for redox reactions. The isotopic composition of O and H in water was determined in order to calculate mixing ratios between the local groundwater and the infiltrated surface water. Three distinct processes in the reduction of the DOC content were traced using isotopic methods and concentration analyses of DIC and DOC: (1) the decomposition of DOC (2) adsorption of DOC on mineral matter, and (3) the dilution of artificially recharged water by mixing with local groundwater. The largest decrease (44%) in the DOC content occurred during the early stage of subsurface flow, within 350 m of the infiltration ponds. The reduction of DOC was accompanied by an equal increase in DIC and a significant drop in δ 13CDIC. This change is attributed to the oxidative decomposition of DOC. A further 23% decrease in DOC is attributed to adsorption and a final drop of 14% to dilution with local groundwater

  4. Seasonal changes in stable carbon isotope ratios within annual growth rings of Pinus radiata

    International Nuclear Information System (INIS)

    The stable isotope composition of photosynthetically assimilated carbon (δ13C) is determined by the ratio of the leaf internal CO2 concentration (ci) to that of the ambient air (ca), and so reflects the contribution of both stomatal conductance (gs) and the rate of photosynthesis (A). Assimilated carbon which is subsequently laid down as wood in annual growth rings may therefore represent a time integrated record of physiological responses by the whole tree to seasonal changes in the environmental variables regulating growth. We analysed the stable carbon isotope composition of Pinus radiata wood collected from two plantation forest sites in New Zealand which differ markedly in temperature, rainfall and soil characteristics. For both sites, discs were cut from the stem of several trees near ground level and whole wood samples were taken from within individual annual growth rings over a number of years. At one site, diameter bands were installed over the 1994 - 1996 growing seasons in order to date precisely the formation of wood during that time. Trees at each site consistently showed a seasonal pattern in the stable isotope composition of wood within individual growth rings. The amplitude of seasonal δ13C variation at the wet and dry sites were 1-2 per thousand and 4 per thousand respectively. Mean δ13C values from the wet site were 3 per thousand more 13C depleted than those from the dry site implying lower water-use efficiency (carbon assimilation per unit transpiration). A process-based, model of stomatal conductance and CO2 assimilation was combined with a soil-water balance model to estimate the average daily leaf-level intercellular CO2 concentration (ci). Over two growing seasons at each site there was generally good agreement between mean canopy-level ci derived from the tree-ring δ13C data and modelled leaf-level ci levels. Further, the ratio of annual CO2 assimilation to transpiration estimated by the model for each site correlated with the

  5. Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.

    Energy Technology Data Exchange (ETDEWEB)

    Keck, B D; Ognibene, T; Vogel, J S

    2010-02-05

    Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of any separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30 fg

  6. On-line coupling of the MAT 251 with a Carlo Erba elemental analyzer for carbon isotope ratio measurements

    International Nuclear Information System (INIS)

    For carbon isotope investigations with a moderate precision demand of about 0.2 per mil in the isotope ratio fast and reliable results are attained by on line combination of the ANA 1500 Elemental Analyzer and the MAT 251 Isotope Mass Spectrometer. The crucial point hereof is the gas splitting device. By proper design and adjustment of the analytical parameters, good sample efficiency and a sharp CO2 bulk within the He stream is reached. The main characteristics of this combined equipment are described and some isotopic results of organic and anorganic carbon in lake sediment-samples are given as well as deltasup13C-analyses of spiritous liquors. (Author)

  7. Determination of site-specific carbon isotope ratios at natural abundance by carbon-13 nuclear magnetic resonance spectroscopy.

    Science.gov (United States)

    Caer, V; Trierweiler, M; Martin, G J; Martin, M L

    1991-10-15

    Site-specific natural isotope fractionation of hydrogen studied by deuterium NMR (SNIF-NMR) spectroscopy is a powerful source of information on hydrogen pathways occurring in biosyntheses in natural conditions. The potential of the carbon counterpart of this method has been investigated and compared. Three typical molecular species, ethanol, acetic acid, and vanillin, have been considered. Taking into account the requirements of quantitative 13C NMR, appropriate experimental procedures have been defined and the repeatability and reproducibility of the isotope ratio determinations have been checked in different conditions. It is shown that the carbon version of the SNIF-NMR method is capable of detecting small differences in the carbon-13 content of the ethyl fragment of ethanols from different botanical or synthetic origins. These results are in agreement with mass spectrometry determinations of the overall carbon isotope ratios. Deviations with respect to a statistical distribution of 13C have been detected in the case of acetic acid and vanillin. However, since the method is very sensitive to several kinds of systematic error, only a relative significance can be attached at present to the internal parameters directly accessible. Isotope dilution experiments have also been carried out in order to check the consistency of the results. In the present state of experimental accuracy, the 13C NMR method is of more limited potential than 2H SNIF-NMR spectroscopy. However it may provide complementary information. Moreover it is particularly efficient for detecting and quantifying adulterations that aim to mimic the overall carbon-13 content of a natural compound by adding a selectivity enriched species to a less expensive substrate from a different origin. PMID:1759714

  8. Detecting isotopic ratio outliers

    International Nuclear Information System (INIS)

    An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers. 6 refs., 3 figs., 3 tabs

  9. Carbon isotope ratios in crassulacean Acid metabolism plants: seasonal patterns from plants in natural stands.

    Science.gov (United States)

    Szarek, S R

    1976-09-01

    A year round study of photosynthesis and carbon isotope fractionation was conducted with plants of Opuntia phaeacantha Engelm. and Yucca baccata Torr. occurring in natural stands at elevations of 525, 970, 1450 and 1900 m. Plant water potentials and the daytime pattern of (14)CO(2) photosynthesis were similar for all cacti along the elevational gradient, despite significant differences in temperature regime and soil water status. Carbon isotope ratios of total tissue and soluble extract fractions were relatively constant throughtout the entire year. Additionally, the sigma(13)C values were similar in all plants of the same species along the elevational gradient, i.e. -12.5 +/- 0.86 per thousand for O. phaeacantha and -15.7 +/- 0.95 per thousand for Y. baccata. The results of this study indicate Crassulacean acid metabolism predominates as the major carbon pathway of these plants, which do not facultatively utilize the reductive pentose phosphate cycle of photosynthesis as the primary carboxylation reaction. PMID:16659680

  10. Analysis of carbon isotope ratio variation in CO2 efflux from forest floor

    International Nuclear Information System (INIS)

    To model carbon cycle in surface soil, variation of carbon-14 isotope ratio in soil-respired CO2 efflux from a larch forest floor was investigated by field measurements with an accumulation chamber, laboratory experiments on soil organic matter (SOM) decomposition and numerical simulations. The field measurements showed a characteristic variation in δ14C with large amplitude of diurnal variation in winter. From laboratory experiments, SOM decomposition was modeled as a function of soil temperature, CO2 concentration in ambient air and soil depth at a fixed soil moisture condition typical of the objective forest. An inversely proportional dependency on CO2 concentration was found. Less efficient SOM decomposition in deeper soil per unit content of SOM was also modeled. By using these results on SOM decomposition, numerical simulations were carried out to show that the diurnal and annual variation in δ14C found in the field measurements could be explained by change in depth profile of SOM decomposition. (author)

  11. Oxygen and carbon isotope ratios of hydrothermal minerals from Yellowstone drill cores

    Science.gov (United States)

    Sturchio, N.C.; Keith, T.E.C.; Muehlenbachs, K.

    1990-01-01

    Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface (in situ temperatures ranging from 81 to 199??C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The ??18O values of the thirty-two analyzed silica samples (quartz, chalcedony, ??-cristobalite, and ??-cristobalite) range from -7.5 to +2.8???. About one third of the silica 7samples have ??18O values that are consistent with isotopic equilibrium with present thermal waters; most of the other silica samples appear to have precipitated from water enriched in 18O (up to 4.7???) relative to present thermal water, assuming precipitation at present in situ temperatures. Available data on fluid-inclusion homogenization temperatures in hydrothermal quartz indicate that silica precipitation occurred mostly at temperatures above those measured during drilling and imply that 15O enrichments in water during silica precipitation were generally larger than those estimated from present conditions. Similarly, clay minerals (celadonite and smectite) have ??18O values higher (by 3.5 to 7.9???) than equilibrium values under present conditions. In contrast, all eight analyzed calcite samples are close to isotopic equilibrium with present thermal waters. The frequent incidence of apparent 18O enrichment in thermal water from which the hydrothermal minerals precipitated may indicate that a higher proportion of strongly 18O-enriched deep hydrothermal fluid once circulated through shallow portions of the Yellowstone system, or that a recurring transient 18O-enrichment effect occurs at shallow depths and is caused either by sudden decompressional boiling or by isotopic exchange at low water/rock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are consistent with deposition

  12. An analytical system for stable isotope analysis on carbon monoxide using continuous-flow isotope-ratio mass spectrometry

    Science.gov (United States)

    Pathirana, S. L.; van der Veen, C.; Popa, M. E.; Röckmann, T.

    2015-12-01

    A fully automated system for the determination of δ13C and δ18O in atmospheric CO has been developed. CO is extracted from an air sample and converted into carbon dioxide (CO2) using the Schütze reagent. The isotopic composition is determined with an isotope-ratio mass spectrometer (IRMS) technique. The entire system is continuously flushed with high-purity helium (He), the carrier gas. The blank signal of the Schütze reagent is ~ 4 nmol mol-1, or 1-3 % of the typical sample size. The repeatability is 0.1 ‰ for δ13C and 0.2 ‰ for δ18O. The peak area allows for simultaneous determination of the mole fraction with an analytical repeatability of ~ 0.7 nmol mol-1 for 100 mL of ambient air (185.4 nmol mol-1 of CO). An automated single measurement is performed in only 18 min, and the achieved time efficiency (and small volume of sample air) allows for repetitive measurements practically.

  13. Method based on isotope ratio mass spectrometry for evaluation of carbon activation in the reactor graphite

    International Nuclear Information System (INIS)

    The general idea of this work is to introduce an evaluation method to restore the irradiation parameters of graphite or other carbonaceous materials using experimental and modelling results of 13C generation in the irradiated material. The method is based on coupling of stable isotope ratio mass spectrometry and computer modelling of the reactor core to evaluate the realistic characteristics of the reactor core such as the neutron fluence in any position of the reactor graphite stack or other graphite constructions. The generation of carbon isotopes 13C and 14C in the irradiated graphite of the RBMK-1500 reactor has been estimated by modelling of the reactor core with computer codes MCNPX and CINDER90. Good agreement of simulated and measured Δ13C/12C values in graphite of the central part of the reactor core indicates that the neutron flux (1.40 x 1014 n/cm2 s) is modelled accurately in the graphite sleeve of the fuel channel. The simulated activity of 14C is compared with the one measured by the β spectrometry technique. Results indicate that production of 14C from 14N in the RBMK-1500 reactor is considerable and has to be taken into account in order to make proper evaluation of 14C activity. Measured 14C specific activity values correspond to 15 ± 4 ppm impurity of 14N in graphite samples from the RBMK-1500 reactor core.

  14. Estimation of food composition of Hodotermes mossambicus (Isoptera: Hodotermitidae) based on observations and stable carbon isotope ratios

    Institute of Scientific and Technical Information of China (English)

    Craig T. Symes; Stephan Woodborne

    2011-01-01

    The diet of the harvester termite Hodotermes mossambicus was investigated at two sites with distinct dietary components: C4 grasses (δ13 C isotope values, -13.8‰to -14.0‰) and C3 plants (δ13C isotope values, -25.6‰ to -27.1‰). By comparing observations of food items carried into the colony by the termites and carbon isotope ratios of whole termites (that determined assimilated carbon), the relative proportion of the C3 and C4 plant food components of the termite diet was estimated. There was agreement between the observational data and stable carbon isotopic data, with grass representing approximately 93% of the diet of H, mossambicus at two study sites (urban and rural) on the South African highveld. However, when correcting for mass of food items, that is, C3 and C4, carried by termites, the proportion of grass (C4) in the diet may be underestimated.

  15. Isotopic Ratios of Carbon and Oxygen in Titan's CO using ALMA

    CERN Document Server

    Serigano, Joseph; Cordiner, Martin A; Irwin, Patrick G J; Teanby, Nicholas A; Charnley, Steven B; Lindberg, Johan E

    2016-01-01

    We report interferometric observations of carbon monoxide (CO) and its isotopologues in Titan's atmosphere using the Atacama Large Millimeter/submillimeter Array (ALMA). The following transitions were detected: CO (J = 1-0, 2-1, 3-2, 6-5), $^{13}$CO (J = 2-1, 3-2, 6-5), C$^{18}$O (J = 2-1, 3-2), and C$^{17}$O (J = 3-2). Molecular abundances and the vertical atmospheric temperature profile were derived by modeling the observed emission line profiles using NEMESIS, a line-by-line radiative transfer code. We present the first spectroscopic detection of $^{17}$O in the outer solar system with C$^{17}$O detected at > 8$\\sigma$ confidence. The abundance of CO was determined to be 49.6 ${\\pm}$ 1.8 ppm, assumed to be constant with altitude, with isotopic ratios $^{12}$C/$^{13}$C = 89.9 ${\\pm}$ 3.4, $^{16}$O/$^{18}$O = 486 ${\\pm}$ 22, and $^{16}$O/$^{17}$O = 2917${\\pm}$359. The measurements of $^{12}$C/$^{13}$C and $^{16}$O/$^{18}$O ratios are the most precise values obtained in Titan's atmospheric CO to date. Our res...

  16. Climate and habitat reconstruction using stable carbon and nitrogen isotope ratios of collagen in prehistoric herbivore teeth from Kenya

    Science.gov (United States)

    Ambrose, Stanley H.; DeNiro, Michael J.

    1989-05-01

    Stable carbon and nitrogen isotope ratios have been determined for tooth collagen of 27 prehistoric herbivores from a rock shelter in the central Rift Valley of Kenya. Collagen samples whose isotope ratios were not altered by diagenesis were identified using several analytical methods. During the later Holocene, when the climate was as dry or drier than at present, the isotopic compositions of individual animals are similar to those of modern individuals of the same species. During the earlier Holocene, when the climate was wetter than at present, the δ 15N and δ 13C values are lower than those for their modern counterparts. When diagenetic factors can be discounted and adequate modern comparative data are available, stable isotope analysis of herbivore teeth and bones can be used to evaluate prehistoric climate and habitat conditions.

  17. Assessing diet in savanna herbivores using stable carbon isotope ratios of faeces

    Directory of Open Access Journals (Sweden)

    D. Codron

    2005-06-01

    Full Text Available In African savannas, browse-based resources (@3 plants are isotopically distinct from grasses (@4 plants. The carbon isotopic composition of the basic plant diet is recorded in animal tissues. Mammal faeces are a readily accessible, non-invasive, sample material for temporally resolved dietary reconstructions. Faeces, however, include both undigested plant matter and waste, hence accuracy of dietary calculations could potentially be compromised by shifts in plant isotopic values related to seasonal or spatial differences, or by variability in the isotopic differences between faeces and diet. A controlled feeding study of four ungulate species showed a small, consistent difference between diet and faeces of-0.9 o, irrespective of whether the diet was @3 or C4-based. Results from faeces oftaxa known to be pure grazers, pure browsers, and mixed-feeders from the Kruger National Park were entirely consistent with their diets, but the accuracy of dietary reconstructions is enhanced with data from local plant communities.

  18. Carbon and oxygen isotopic ratio bi-variate distribution for marble artifacts quarry assignment

    International Nuclear Information System (INIS)

    Statistical description, by a Gaussian bi-variate probability distribution of 13 C/12 C and 18 O/16 O isotopic ratios in the ancient marble quarries has been done and the new method for obtaining the confidence level quarry assignment for marble artifacts has been presented. (author) 8 figs., 3 tabs., 4 refs

  19. Diet selection by steers using microhistological and stable carbon isotope ratio analyses.

    Science.gov (United States)

    Bennett, L L; Hammond, A C; Williams, M J; Chase, C C; Kunkle, W E

    1999-08-01

    Two methods of determining diet botanical composition, microhistological (MH), and stable carbon isotope ratio (CR) analyses were used to determine botanical composition of ingesta and fecal grab samples in steers grazing rhizoma peanut-mixed tropical grass pastures. Three pastures were used over two grazing seasons, 1992 and 1993, in Brooksville, FL. A weighted-disc double-sampling technique was used to determine forage mass and botanical composition, percentage of rhizoma peanut (Arachis glabrata), grass (Paspalum notatum and Cynodon dactlyon), and forb (primarily Chenopodium ambrosioides) on offer every 28 d throughout the grazing seasons. There was an effect of sampling date (P<.001), sampling date x pasture (P<.001), and sampling date x year (P<.001) on forage mass on offer. There was a pasture x year x sampling date interaction (P<.001) for all botanical components. In 1992 and 1993, using cannulated steers sampled every 56 d, there were interactions with year for rhizoma peanut and forb (P<.05), but not for grass with MH analysis (components: rhizoma peanut, grass, and forb). Ingesta and fecal rhizoma peanut (r = .73 and .92 for 1992 and 1993, respectively) and ingesta and fecal forb (r = .86 and .98 for 1992 and 1993, respectively) were positively correlated (P<.001). Ingesta and fecal grass were positively correlated (r = .52, P<.001), but the correlation was not as high. With the CR analysis (components: Calvin cycle [C3] plants and C4-dicarboxylic acid pathway [C4] plants), ingesta and corrected fecal (corrected for in vitro organic matter digestibility [IVOMD]) C3 plants were positively correlated (r = .62; P<.001). Diet composition of fecal grab samples from noncannulated steers, collected on the same sampling schedule as for hand-clipped pasture samples, differed at times due to the complexity of the sward (both rhizoma peanut and forb constituted a single component, C3, in the CR analysis). Based on these results, if there is a substantial

  20. The carbon isotope ratios and contents of mineral elements in leaves of Chinese medicinal plants

    International Nuclear Information System (INIS)

    Leaf carbon isotope ratios and 13 kinds of mineral elements were measured on 36 species of common Chinese medicinal plants in a subtropical monsoon forest of Ding Hu Shan in Guangdong Province. The .delta.13C value were from -26.4 to -32.6%, indicating that all of the species belonged the photosynthetic C3 types. The relative lower value of δ13C was observed in the life form of shrubs. The contents of 7 elements (N, P, K, Ca, Na Mg, Si) were dependent upon the species, life form, medicinal function and medicinal part. Herb type medicine and the used medicinal part of leaves or whole plant showed higher levels of above elements than the others. Among the nine groups with different medicinal functions, it was found that more nitrogen was in the leaves of medicinal plants for hemophthisis, hypertension and stomachic troubles, more phosphorus and potassium were in the leaves for cancer and snake bite medicines, but more calcium and magnesium were in the leaves for curing rheumatics. Ferric, aluminium and manganese were the main composition of microelements in leaves. There were higher content of ferric in leaves for hemophthisis medicine, higher zinc in leaves for cold and hypertension medicine, and higher Cup in leaves of stomachic medicine. It was suggested that the pattern of mineral elements in leaves of Chinese medicinal plants reflected the different properties of absorption and accumulation. Some additional effect due to the high content of certain element might be associated with the main function of that medicine

  1. Barium carbonate sediment sampling for inorganic dissolved carbon using isotope mass ratio spectrometer

    International Nuclear Information System (INIS)

    This paperwork explain the method of water sampling to obtain the precipitate of BaCO3 solutions that will be used to analyze 13C from field work in Kelana Jaya, Selangor, Langkawi, Kedah and Taiping, Perak. The sampling involves collecting of water samples for groundwater from boreholes and surface water from canal, river, pond and ex-mining pond from several locations at the study sites. This study also elaborates the instruments and chemicals used. The main purpose of this sampling is to obtain the precipitate of BaCO3 for 13C analysis of dissolved inorganic carbon (DIC). A correct sampling method according to standard is very important to ensure an accurate and precise result. With this, the data from the laboratory analysis result can be fully utilized to make the interpretation of the pollutants movement. (Author)

  2. Carbon Isotope Measurements of Experimentally-Derived Hydrothermal Mineral-Catalyzed Organic Products by Pyrolysis-Isotope Ratio Mass Spectrometry

    Science.gov (United States)

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

    2011-01-01

    We report results of experiments to measure the C isotope composition of mineral catalyzed organic compounds derived from high temperature and high pressure synthesis. These experiments make use of an innovative pyrolysis technique designed to extract and measure C isotopes. To date, our experiments have focused on the pyrolysis and C isotope ratio measurements of low-molecular weight intermediary hydrocarbons (organic acids and alcohols) and serve as a proof of concept for making C and H isotope measurements on more complicated mixtures of solid-phase hydrocarbons and intermediary products produced during high temperature and high pressure synthesis on mineral-catalyzed surfaces. The impetus for this work stems from recently reported observations of methane detected within the Martian atmosphere [1-4], coupled with evidence showing extensive water-rock interaction during Martian history [5-7]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization reactions [8,9]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [10-12]. Further, recent experiments by Fu et al. [13] focus on examining detailed C isotope measurements of hydrocarbons produced by surface-catalyzed mineral reactions. Work described in this paper details the experimental techniques used to measure intermediary organic reaction products (alcohols and organic acids).

  3. Carbon and nitrogen stable isotope ratios of subtidal benthic invertebrates in an estuarine mangrove ecosystem (Andhra Pradesh, India)

    OpenAIRE

    Bouillon, Steven; Raman, AV; Dauby, P; F. Dehairs

    2002-01-01

    In order to assess the relative trophic importance of mangrove litterfall and aquatic primary production in the mangrove creeks of the Coringa Wildlife Sanctuary (Andhra Pradesh, India) and the adjacent semi-enclosed Kakinada Bay, carbon and nitrogen stable isotope ratios were determined in a variety of benthic invertebrate species collected at 22 sites during the pre-monsoon period (May-June) of 1997 and 1999. delta(13)C values showed little interspecific variation at any given location, but...

  4. Use of carbon and nitrogen stable isotope ratios to assess the effects of environmental contaminants on aquatic food webs

    International Nuclear Information System (INIS)

    In this study, the value of carbon (δ 13C) and nitrogen (δ 15N) stable isotope ratios were determined in nymphs of a top-predator, the common backswimmer (Notonecta glauca L.), collected in 18 m3 outdoor freshwater mesocosms used to assess the fate and ecotoxicological effects of a diphenyl ether herbicide, fomesafen, applied alone or in combination with Agral 90[reg] (mixture of polyethoxylated derivatives of nonylphenol). Both treatments had a negative effect on δ 13C values which may reflect changes in carbon fluxes across food webs in the treated ponds associated with a shift in phytoplankton structure. A decrease in δ 15N values was observed in the nymphs collected in mixture-treated ponds, which was presumably due to an increase in the abundance of rotifers and Chironominae larvae in these ponds. These preliminary results indicate that stable isotope ratios may be used as shortcuts to detect qualitative or quantitative shifts in the structure of aquatic food webs caused by pollutants. - Carbon and nitrogen stable isotope ratios may be used to detect the impact of pollutants on aquatic food webs

  5. Organic carbon isotope ratios of recent sediments from coastal lagoons of the Gulf of Mexico, Mexico

    International Nuclear Information System (INIS)

    The stable carbon isotope composition of sedimentary organic carbon was determined in the sediments of seven coastal lagoons of the Gulf of Mexico, Mexico. For most of the lagoons the delta13C values for sediments ranged from -20.1 to -23.9 parts per thousand. Anomalously low values, -26.8 to 29.3 parts per thousand were determined in sediments of two of the studied lagoons, probably due to the presence of organic carbon from anthropogenic sources, naturally absent in these environments. The delta13C values determined in the tissues of oysters collected at the same time in the different lagoons were very similar to those recorded in the sediments. (author)

  6. Wich Parameter of the Carbonate System Influences the Boron Isotopic Composition and the Boron Calcium Ratio in Foraminiferal Tests?

    Science.gov (United States)

    Kaczmarek, K.; Nehrke, G.; Horn, I.; Langer, G.; Misra, S.; Bijma, J.

    2013-12-01

    We performed culture experiments with the benthic symbiont bearing foraminifer Amphistegina lessonii in order to determine which parameter of the marine carbonate system influences the boron isotopic composition (δ11B) and the boron calcium ratio (B/Ca) in the test. A. lessonii grew for two months in treatments of culture media with decoupled pH-carbonate chemistry. We measured δ11B and B/Ca simultaneously on single tests using a recently new developed mass spectrometric technique. Our results show a clear pH dependence on δ11B. The B/Ca in the shell show a positive correlation with aqueous B(OH)4-/HCO3-.

  7. Stable carbon isotope ratios of lipid biomarkers and their applications in the marine environment

    International Nuclear Information System (INIS)

    Studies on the distribution of lipid biomarkers in the environment help elucidate biogeochemical processes, but recent findings have significantly reduced the specificity of some biomarkers. The analytical development of Gas Chromatography-Combustion-IRMS (GC-C-IRMS) allows the determination of the δ13C of specific biomarkers, thereby improving the veracity of source apportionment. In this report, we present a brief description of the analytical approach for sample preparation and carbon isotope measurements of individual biomarkers. Selected examples of the applications in the use of GC-C-IRMS for biomarker source elucidation in the marine environment and potential applications to paleoclimatological studies are reviewed. (author)

  8. CNO abundances and carbon isotope ratios in evolved stars of the open clusters NGC 2324, NGC 2477, and NGC 3960

    CERN Document Server

    Tautvaisiene, Grazina; Bragaglia, Angela; Randich, Sofia; Zenoviene, Renata

    2016-01-01

    Our main aim is to determine carbon-to-nitrogen and carbon isotope ratios for evolved giants in the open clusters NGC 2324, NGC 2477, and NGC 3960, which have turn-off masses of about 2 Msun, and to compare them with predictions of theoretical models. High-resolution spectra were analysed using a differential synthetic spectrum method. Abundances of carbon were derived using the C2 Swan (0,1) band heads at 5135 and 5635.5 A. The wavelength interval 7940-8130 A with strong CN features was analysed to determine nitrogen abundances and carbon isotope ratios. The oxygen abundances were determined from the [Oi] line at 6300 A. The mean values of the CNO abundances are [C/Fe]=-0.35+-0.06 (s.d.), [N/Fe]=0.28+-0.05, and [O/Fe]=-0.02+-0.10 in seven stars of NGC 2324; [C/Fe]=-0.26+-0.02, [N/Fe]=0.39+-0.04, and [O/Fe]=-0.11+-0.06 in six stars of NGC 2477; and [C/Fe]=-0.39+-0.04, [N/Fe]=0.32+-0.05, and [O/Fe]=-0.19+-0.06 in six stars of NGC 3960. The mean C/N ratio is equal to 0.92+-0.12, 0.91+-0.09, and 0.80+-0.13, resp...

  9. Riparian forest potential to retain sediment and carbon evaluated by the 137Cs fallout and carbon isotopic ratio techniques

    International Nuclear Information System (INIS)

    Riparian forests can provide an important service for aquatic ecosystems by sequestering hill slope-derived sediments. However, the width of a riparian buffer zone required to filter sediments is not yet well-understood. Here are used two complementary tracers to measure sediment retention. The 137Cs technique and the soil carbon isotopic ratios (δ 13C) are utilized to investigate sediment deposition and erosion rates on a slope transect cultivated with sugarcane followed by a secondary riparian forest zone in Iracemapolis, State of Sao Paulo, Brazil. The 137Cs technique and the δ 13C analysis showed that the width of a riparian vegetation in accordance to a Brazilian Environmental Law (N. 4.771/65) was not sufficient in trapping sediments coming from agricultural lands, but indicated the importance of these forests as a conservation measure at the watershed scale. The complementary δ 13C analysis together with soil morphology aspects allowed a better interpretation of the sediment redistribution along the sugarcane and riparian forest transect. (author)

  10. Elucidation of C2 and CN formation mechanisms in laser-induced plasmas through correlation analysis of carbon isotopic ratio

    International Nuclear Information System (INIS)

    Laser ablation molecular isotopic spectrometry (LAMIS) was recently reported for rapid isotopic analysis by measuring molecular emission from laser-induced plasmas at atmospheric pressure. With 13C-labeled benzoic acid as a model sample, this research utilized the LAMIS approach to clarify the formation mechanisms of C2 and CN molecules during laser ablation of organic materials. Because the isotopic ratios in the molecular bands could deviate from statistical distribution depending on their formation pathways, the dominant mechanism can be identified through a comparison of the experimental observed isotopic patterns in the molecular emission with the theoretical statistical pattern. For C2 formation, the experimental 12C12C/13C12C ratios not only support a recombination mechanism through atomic carbon at early delay time but also indicate the presence of other operating mechanisms as the plasma evolves; it is proposed that some of the C2 molecules are released directly from the aromatic ring of the sample as molecular fragments. In contrast, the temporal profiles in the 12C/13C ratios derived from CN emission exhibited opposite behavior with those derived from C2 emission, which unambiguously refutes mechanisms that require C2 as a precursor for CN formation; CN formation likely involves atomic carbon or species with a single carbon atom. - Highlights: • C2 and CN formation mechanisms during laser ablation of organic material studied • Some C2 molecules are directly desorbed from the organic compound. • C2 molecules are not important precursor for CN-radical formation

  11. A novel framework for quantifying past methane recycling by Sphagnum-methanotroph symbiosis using carbon and hydrogen isotope ratios of leaf wax biomarkers

    Science.gov (United States)

    Nichols, Jonathan E.; Isles, Peter D. F.; Peteet, Dorothy M.

    2014-05-01

    concentration of atmospheric methane is strongly linked to variations in Earth's climate. Currently, we can directly reconstruct the total atmospheric concentration of methane, but not individual terms of the methane cycle. Northern wetlands, dominated by Sphagnum, are an important contributor of atmospheric methane, and we seek to understand the methane cycle in these systems. We present a novel method for quantifying the proportion of carbon Sphagnum assimilates from its methanotrophic symbionts using stable isotope ratios of leaf-wax biomarkers. Carbon isotope ratios of Sphagnum compounds are determined by two competing influences, water content and the isotope ratio of source carbon. We disentangled these effects using a combined hydrogen and carbon isotope approach. We constrained Sphagnum water content using the contrast between the hydrogen isotope ratios of Sphagnum and vascular plant biomarkers. We then used Sphagnum water content to calculate the carbon isotope ratio of Sphagnum's carbon pool. Using a mass balance equation, we calculated the proportion of recycled methane contributed to the Sphagnum carbon pool, "PRM." We quantified PRM in peat monoliths from three microhabitats in the Mer Bleue peatland complex. Modern studies have shown that water table depth and vegetation have strong influences on the peatland methane cycle on instrumental time scales. With this new approach, δ13C of Sphagnum compounds are now a useful tool for investigating the relationships among hydrology, vegetation, and methanotrophy in Sphagnum peatlands over the time scales of entire peatland sediment records, vital to our understanding of the global carbon cycle through the Late Glacial and Holocene.

  12. A Novel Framework for Quantifying past Methane Recycling by Sphagnum-Methanotroph Symbiosis Using Carbon and Hydrogen Isotope Ratios of Leaf Wax Biomarkers

    Science.gov (United States)

    Nichols, Jonathan E.; Isles, Peter D. F.; Peteet, Dorothy M.

    2014-01-01

    The concentration of atmospheric methane is strongly linked to variations in Earth's climate. Currently, we can directly reconstruct the total atmospheric concentration of methane, but not individual terms of the methane cycle. Northern wetlands, dominated by Sphagnum, are an important contributor of atmospheric methane, and we seek to understand the methane cycle in these systems. We present a novel method for quantifying the proportion of carbon Sphagnum assimilates from its methanotrophic symbionts using stable isotope ratios of leaf-wax biomarkers. Carbon isotope ratios of Sphagnum compounds are determined by two competing influences, water content and the isotope ratio of source carbon. We disentangled these effects using a combined hydrogen and carbon isotope approach. We constrained Sphagnum water content using the contrast between the hydrogen isotope ratios of Sphagnum and vascular plant biomarkers. We then used Sphagnum water content to calculate the carbon isotope ratio of Sphagnum's carbon pool. Using a mass balance equation, we calculated the proportion of recycled methane contributed to the Sphagnum carbon pool, 'PRM.' We quantified PRM in peat monoliths from three microhabitats in the Mer Bleue peatland complex. Modern studies have shown that water table depth and vegetation have strong influences on the peatland methane cycle on instrumental time scales. With this new approach, delta C-13 of Sphagnum compounds are now a useful tool for investigating the relationships among hydrology, vegetation, and methanotrophy in Sphagnum peatlands over the time scales of entire peatland sediment records, vital to our understanding of the global carbon cycle through the Late Glacial and Holocene.

  13. Use of stable carbon and nitrogen isotope ratios in size segregated aerosol particles for the O/I penetration evaluation

    Science.gov (United States)

    Garbaras, Andrius; Garbariene, Inga; Masalaite, Agne; Ceburnis, Darius; Krugly, Edvinas; Kvietkus, Kestutis; Remeikis, Vidmantas; Martuzevicius, Dainius

    2015-04-01

    Stable carbon and nitrogen isotope ratio are successfully used in the atmospheric aerosol particle source identification [1, 2], transformation, pollution [3] research. The main purpose of this study was to evaluate the penetration of atmospheric aerosol particles from outdoor to indoor using stable carbon and nitrogen isotope ratios. Six houses in Kaunas (Lithuania) were investigated during February and March 2013. Electrical low pressure impactor was used to measure in real time concentration and size distribution of outdoor aerosol particles. ELPI+ includes 15 channels covering the size range from 0.017 to 10.0 µm. The 25 mm diameter aluminium foils were used to collect aerosol particles. Gravimetric analysis of samples was made using microbalance. In parallel, indoor aerosol samples were collected with a micro-orifice uniform deposition impactor (MOUDI model 110), where the aerosol particles were separated with the nominal D50 cut-off sizes of 0.056, 0.1, 0.18,0.32,0.56, 1.0, 1.8, 3.2, 5.6, 10, 18 μm for impactor stages 1-11, respectively. The impactor was run at a flow rate of 30 L/min. Air quality meters were used to record meteorological conditions (temperature, relative humidity) during the investigated period. All aerosol samples were analyzed for total carbon (TC) and total nitrogen (TN) contents and their isotopic compositions using elemental analyzer (EA) connected to the stable isotope ratio mass spectrometer (IRMS). TC concentration in indoors ranged from 1.5 to 247.5 µg/m3. During the sampling period outdoors TN levels ranged from 0.1 to 10.9 µg/m3. The obtained outdoor δ13C(PM2.5) values varied from -24.21 to -26.3‰, while the δ15N values varied from 2.4 to 11.1 ‰ (average 7.2±2.5 ‰). Indoors carbonaceous aerosol particles were depleted in 13C compared to outdoors in all sampling sites. This depletion in δ13C varied from 0.1 to 3.2 ‰. We think that this depletion occurs due ongoing chemical reactions (oxidation) when aerosol

  14. The application of stable carbon isotope ratios as water quality indicators in coastal areas of Karachi, Pakistan

    International Nuclear Information System (INIS)

    Stable carbon isotope ratios (δ13C) of total dissolved inorganic carbon (TDIC), total inorganic and organic carbon in bottom sediments, as well as sea plants in polluted water sources, non-polluted Karachi Sea water and pollution recipients are used to elaborate pollution scenario of shallow marine environment off Karachi coast. These results are supplemented with stable isotope composition of nitrogen (δ15N) in seaweeds and mangroves, toxic/trace metal concentration in sea-bottom sediments, total Coliform bacterial population, electrical conductivity, temperature and turbidity. Isotopic data shows that the mangrove ecosystem and the tidal fluctuations play a key role in controlling contamination inventories in shallow sea water off Karachi coast, specifically the Manora Channel. The Karachi harbour zone is found to be the most heavily polluted marine site in Manora channel during high as well as low tide regimes. Significant concentrations of toxic metals such as Pb, Ni, Cr, Zn, V, U are observed in off-shore sediments of Karachi coast. The results show that sewage and industrial wastes are the main sources of heavy metal pollution in Karachi harbour, Manora Channel exit zone and the southeast coast. However, as compared to other coastal areas, the Karachi coast is moderately polluted. Studies suggest incorporation of quick remedial measures to combat pollution in shallow marine environments off Karachi Coast. (author)

  15. Carbon and hydrogen isotope ratios of bacterial methane and its formation mechanism

    International Nuclear Information System (INIS)

    Anaerobic incubations of paddy soil collected from Konosu, Japan, were carried out for 10 weeks to clarify the general principles that govern the variation of carbon isotopic composition of bacterial methane from freshwater areas. The δ13C value of produced CH4 was highly variable ranging from -60 to -33%, corresponding to change in its formation pathways: acetate fermentation and CO2/H2 reduction. The δ13C value of CH4 from CO2/H2 was estimated as -77 to -60%, adopting 45% of δ13C difference between the CH4 and its source CO2. The δ13C value of methyl carbon of acetate accumulated with addition of inhibitor for methanogenesis ranged from -43 to -30%, which was considered with the δ13C value of CH4 from acetate. Variability of CH4 δ13C resulted from the difference in contribution of each biological process. It was demonstrated that δ13C value of methane was a useful indicator for assessing the contribution of each process in wetlands and paddy fields. (author)

  16. Source characterization using compound composition and stable carbon isotope ratio of PAHs in sediments from lakes, harbor, and shipping waterway

    International Nuclear Information System (INIS)

    Molecular compositions and compound specific stable carbon isotope ratios of polycyclic aromatic hydrocarbons (PAH) isolated from sediments were used to characterize possible sources of contamination at an urban lake, a harbor, a shipping waterway, and a relatively undisturbed remote lake in the northwest United States. Total PAH concentrations in urban lake sediments ranged from 66.0 to 16,500 μg g-1 dry wt. with an average of 2600 μg g-1, which is ∼ 50, 100, and 400 times higher on average than PAH in harbor (48 μg g-1 on average), shipping waterway (26 μg g-1), and remote lake (7 μg g-1) sediments, respectively. The PAH distribution patterns, methyl phenanthrene/phenanthrene ratios, and a pyrogenic index at the sites suggest a pyrogenic origin for PAHs. Source characterization using principal component analysis and various molecular indices including C2-dibenzothiophenes/C2-phenanthrenes, C3-dibenzothiophenes/C3-phenanthrenes, and C2-chrysenes/C2-phenanthrenes ratios, was able to differentiate PAH deposited in sediments from the four sites. The uniqueness of the source of the sediment PAHs from urban lake was also illustrated by compound specific stable carbon isotope analysis. It was concluded that urban lake sediments are accumulating PAH from sources that are unique from contamination detected at nearby sites in the same watershed

  17. Stable carbon isotope ratios of plankton carbon and sinking organic matter from the Atlantic sector of the Southern Ocean

    International Nuclear Information System (INIS)

    The stable carbon isotope composition of particulate organic carbon (POC) from plankton, sediment trap material and surface sediments from the Atlantic sector of the Southern Ocean were determined. Despite low and constant water temperatures, large variations in the delta13C values of plankton were measured. 13C enrichments of up to 10promille coincided with a change in the diatom assemblage and a two-fold increase in primary production. Increased CO2 consumption as a result of rapid carbon fixation may result in diffusion limitation reducing the magnitude of the isotope fractionation. The delta13C values of plankton from sea-ice cores display a relationship with the chlorophyll a content. High 'ice-algae' biomass, in combination with a limited exchange with the surrounding seawater, results in values of about -18 to -20promille. It is assumed that these values are related to a reduced CO2 availability in the sea-ice system. In comparison with plankton, sinking krill faeces sampled by traps can be enriched by 2-5promille in 13C (e.g. central Bransfield Strait). In contrast, the transport of particles in other faeces, diatom aggregates or chains may result in minor isotope changes (e.g. Drake Passage, Powell Basin, NW Weddell Sea). A comparison between the δ13C values of sinking matter and those of surface sediments reveals that 13C enrichments of up to 3-4promille may occur at the sediment-water boundary layer. These isotopic changes are attributed to high benthic respiration rates. (author). 44 refs.; 6 figs

  18. A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms

    Directory of Open Access Journals (Sweden)

    P. Ziveri

    2011-08-01

    Full Text Available The oxygen isotopic composition (δ18O of calcium carbonate of planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. The calibration of paloeceanographic proxies relies in general on empirical relationships derived from experiments on extant species. Laboratory experiments have more often than not revealed that variables other than the target parameter influence the proxy signal, which makes proxy calibration a challenging task. Understanding these secondary or "vital" effects is crucial for increasing proxy accuracy and possibly for developing new biomarkers. We present data from laboratory experiments showing that oxygen isotope fractionation during calcification in the coccolithophore Calcidiscus leptoporus and the calcareous dinoflagellate Thoracosphaera heimii is dependent on carbonate chemistry of seawater in addition to its dependence on temperature. A similar result has previously been reported for planktonic foraminifera, suggesting that the [CO32−] effect on δ18O is universal for unicellular calcifying planktonic organisms. The slopes of the δ18O/[CO32−] relationships range between −0.0243 (μmol kg−1−1 (calcareous dinoflagellate T. heimii and the previously published 0.0022 (μmol kg−1−1 (non-symbiotic planktonic foramifera Orbulina universa, while C. leptoporus has a slope of 0.0048 (μmol kg−1−1. We present a simple conceptual model, based on the contribution of δ18O-enriched HCO3 to the CO32− pool in the calcifying vesicle, which can explain the [CO32−] effect on δ18O for the different unicellular calcifiers. This approach provides a new insight into biological fractionation in

  19. The influences of cultivation setting on inflorescence lipid distributions, concentrations, and carbon isotope ratios of Cannabis sp.

    Science.gov (United States)

    Tipple, Brett J; Hambach, Bastian; Barnette, Janet E; Chesson, Lesley A; Ehleringer, James R

    2016-05-01

    While much is known about how the growth environment influences many aspects of floral morphology and physiology, little is known about how the growth setting influences floral lipid composition. We explored variations in paraffin wax composition in Cannabis sp., a cash crop grown both indoors and outdoors across the United States today. Given an increased focus on regulation of this crop, there are additional incentives to certify the setting of Cannabis cultivation. To understand the impacts of the growth environment, we studied distributions, concentrations, and carbon isotope ratios of n-alkanes isolated from Cannabis sp. inflorescences to assess if variations within these lipid parameters were related to known growth settings of specimens seized by federal agents. We found that Cannabis plants cultivated under open-field settings had increased inflorescence paraffin wax abundances and greater production of lower molecular weight n-alkanes relative to plants grown in enclosed environments. Further, the carbon isotope ratios of n-C29 from Cannabis plants grown in enclosed environments had relatively lower carbon isotope (δ(13)C) values compared to plants from open-field environments. While this set of observations on seized plant specimens cannot address the particular driver behind these observations, we posit that (a) variations in irradiance and/or photoperiod may influence the distribution and concentration of inflorescence lipids, and (b) the δ(13)C value of source CO2 and lipid concentration regulates the δ(13)C values of inflorescence n-C29 and bulk Cannabis plant materials. Nonetheless, by using a cultivation model based on δ(13)C values of n-C29, the model correctly identified the growth environment 90% of time. We suggest that these lipid markers may be used to trace cultivation methods of Cannabis sp. now and become a more powerful marker in the future, once the mechanism(s) behind these patterns is uncovered. PMID:27045381

  20. Near infrared spectroscopy of M dwarfs. IV. A preliminary survey on the carbon isotopic ratios in M dwarfs

    CERN Document Server

    Tsuji, Takashi

    2016-01-01

    Based on the medium resolution near infrared spectra of 13CO (3,1) band, carbon isotopic ratios are estimated in 48 M dwarfs, for which we had determined the carbon and oxygen abundances from CO and H2O lines, respectively. We find clear evidence for the presence of a 13CO feature for the first time in the spectra of M dwarfs. The spectral resolution of our observed data, however, is not high enough to analyze the 13CO feature directly. Instead, we compare observed spectrum with synthetic spectra assuming 12C/13C = 10, 25, 50, 100, and 200 for each of 48 M dwarfs and estimate the best possible 12C/13C ratio by the chi-square analysis. The resulting 12C/13C ratios in M dwarfs distribute from 39 to a lower limit of 200. The mean value of 31 M dwarfs for which 12C/13C ratios are determined is 12C/13C = 87 +- 21 (p.e.), and that of 48 M dwarfs including those with the lower limit of 200 is 12C/13C > 127 +- 41 (p.e.). These results are somewhat larger than the 12C/13C ratio of the present interstellar matter (ISM)...

  1. Carbon and nitrogen isotopic ratios of suspended particulate organic matter (SPOM) in the Black Sea water column

    Science.gov (United States)

    Çoban-Yıldız, Yeşim; Altabet, Mark A.; Yılmaz, Ayşen; Tuğrul, Süleyman

    2006-08-01

    Carbon and nitrogen isotopic ratios ( δ15N and δ13C) of suspended particulate organic matter (SPOM) in the water column of the Black Sea were measured at a total of nine stations in September-October (autumn) 1999 and May 2001. For comparison, a station in the Mediterranean Sea and one in the Sea of Marmara were sampled in October 1999. Large-sized particle samples, as well as samples of surface sediment were also collected for N and C isotopic analysis. The results revealed important vertical and regional variations in N and C isotopic composition. Seasonal variations in SPOM δ15N and δ13C were not apparent. SPOM in the euphotic zone (EZ), oxycline, and suboxic/anoxic interface layers of the water column was characterized by distinct isotopic composition. In the EZ, the N and C isotopic ratios of SPOM were in the range typically observed for plankton-derived SPOM in the surface ocean (EZ means ranged from 2.7‰ to 5.9‰ for δ15N and from -24.0‰ to -21.5‰ for δ13C). Shelf region SPOM had higher δ15N and lower δ13C (EZ means of 5.9‰ and -24.0‰, respectively). Large-sized particles (LPOM) collected by zooplankton net tows had ˜3‰ higher δ15N values compared to SPOM, indicating fractionation during trophic transfer of nitrogen. SPOM in the oxycline increased by 3-6‰ for δ15N, while δ13C decreased by -2‰ to -4‰, which may be attributed to greater lipid content. In the suboxic/anoxic interface zone, SPOM isotopic ratios ( δ15N as low as 0.0‰ to -8.0‰) suggest chemoautotrophic production leading to dominance of new, in situ produced organic matter. The location of the most negative δ15N values indicates that chemoautotrophic production is most intense at the shelf-break regions, possibly enhanced by mixing of oxygenated and nitrate-rich Mediterranean inflow waters with suboxic/anoxic Black Sea water.

  2. Modelling the Phanerozoic carbon cycle and climate: constraints from the 87Sr/86Sr isotopic ratio of seawater

    Science.gov (United States)

    Francois, L. M.; Walker, J. C.

    1992-01-01

    A numerical model describing the coupled evolution of the biogeochemical cycles of carbon, sulfur, calcium, magnesium, phosphorus, and strontium has been developed to describe the long-term changes of atmospheric carbon dioxide and climate during the Phanerozoic. The emphasis is on the effects of coupling the cycles of carbon and strontium. Various interpretations of the observed Phanerozoic history of the seawater 87Sr/86Sr ratio are investigated with the model. More specifically, the abilities of continental weathering, volcanism, and surface lithology in generating that signal are tested and compared. It is suggested that the observed fluctuations are mostly due to a changing weatherability over time. It is shown that such a conclusion is very important for the modelling of the carbon cycle. Indeed, it implies that the conventional belief that the evolution of atmospheric carbon dioxide and climate on a long time scale is governed by the balance between the volcanic input of CO2 and the rate of silicate weathering is not true. Rather carbon exchanges between the mantle and the exogenic system are likely to have played a key role too. Further, the increase of the global weathering rates with increasing surface temperature and/or atmospheric CO2 pressure usually postulated in long-term carbon cycle and climate modelling is also inconsistent with the new model. Other factors appear to have modulated the weatherability of the continents through time, such as mountain building and the existence of glaciers and ice sheets. Based on these observations, a history of atmospheric carbon dioxide and climate during Phanerozoic time, consistent with the strontium isotopic data, is reconstructed with the model and is shown to be compatible with paleoclimatic indicators, such as the timing of glaciation and the estimates of Cretaceous paleotemperatures.

  3. An analytical system for studying the stable isotopes of carbon monoxide using continuous flow-isotope ratio mass spectrometry (CF-IRMS

    Directory of Open Access Journals (Sweden)

    S. L. Pathirana

    2015-02-01

    Full Text Available In the atmosphere, carbon monoxide (CO is the major sink for the hydroxyl radical (OH •, has multiple anthropogenic and natural sources and considerable spatial and seasonal variability. Measurements of CO isotopic composition are useful in constraining the strengths of its individual source and sink processes and thus its global cycle. A fully automated system for δ13C and δ18O analysis has been developed to extract CO from an air sample, convert CO into carbon dioxide (CO2 using the Schütze reagent, and then determine the isotopic composition in an isotope ratio mass spectrometer (IRMS. The entire system is continuously flushed with high-purity helium (He, the carrier gas. The blank signal of the Schütze reagent is only 1–3% of the typical sample size. The repeatability is 0.1‰ for δ13C and 0.2‰ for δ18O. The peak area allows simultaneous determination of the mole fraction with an analytical repeatability of ~0.7 nmol mol−1 for 100 mL of typical ambient air (185.4 nmol mol−1 of CO. A single, automated, measurement is performed in 18 min, so multiple measurements can be combined conveniently to improve precision.

  4. Influence of Reproduction on Stable-Isotope Ratios: Nitrogen and Carbon Isotope Discrimination between Mothers, Fetuses, and Milk in the Fin Whale, a Capital Breeder.

    Science.gov (United States)

    Borrell, A; Gómez-Campos, E; Aguilar, A

    2016-01-01

    In mammals, the influence of gestation and lactation on the tissue stable-isotope ratios of females, fetuses, and milk remains poorly understood. Here we investigate the incidence of these events on δ(13)C and δ(15)N values in fin whales sampled off northwestern Spain between 1983 and 1985. The effect of gestation on tissue stable-isotope ratios was examined in the muscle of pregnant females (n = 13) and their fetuses (n = 10) and that of lactation in the muscle of nursing females (n = 21) and their milk (n = 25). Results suggest that fetuses are enriched compared to their mothers in both (15)N (Δ(15)N = 1.5‰) and (13)C (Δ(13)C =1.1‰), while, compared to muscle, milk is enriched in (15)N (Δ(15)N = 0.3‰) but depleted in (13)C (Δ(13)C = -0.62‰). This pattern is consistent with that previously observed for other species that, like the fin whale, rely on endogenous energy during reproduction, and it substantiates a general difference in the physiological processing of nitrogen and carbon balances between income and capital breeders. These findings are relevant to the understanding of the energetic balance of mammals during gestation and lactation and are central when inferences on trophic ecology are drawn from isotopic values of reproductive females. PMID:27082523

  5. Measurements of hydrogen, oxygen and carbon isotope ratios by SIRA 10 mass spectrometer and some problems of their quality assurance

    International Nuclear Information System (INIS)

    Full text: Hydrogen and oxygen are two chemical elements that combined between them forms the water molecules. Hydrogen has two stable isotopes 1H and 2H, with abundance, respectively, 99.985 % and 0.015 %, while the oxygen has three stable isotopes 16O, 17O, 18O with the abundance, respectively, 99.756 %, 0.039 %, 0.205 %. Hydrogen and oxygen stable isotopes, in our laboratory, are used in the hydrology and hydrogeology studies. The 'δ' values of hydrogen and oxygen of water samples are expressed in per mille with respect to SMOW, while, for carbon is expressed in per mille with respect to PDB. The isotopic compositions of these elements are measured using the SIRA 10 mass spectrometer, which is similar with the Nier mass spectrometer. SIRA 10 mass spectrometer, destined for the measurements of the isotopic ratios of the light elements, is equipped with double inlet system and with three collectors system (for the oxygen, carbon, nitrogen etc. isotopes) and double collector system for the hydrogen isotopes. The vacuum 10-9 torr is realized by the two oil diffusion pumps. The gas samples (H2, CO2, etc.) are admitted to the ion source of the mass spectrometer, where are transformed into positive ions by the electron impact. The magnetic field is normal to the path of the ions and is realized by a permanent magnet. The quality assurance of the 'δ' determination dependent from the preparation of the gas samples and from the measurements of the isotopic ratios. Stable isotopes hydrogen of the water samples are measured through the hydrogen gas which is gained from the water by the reduction reaction with metallic Zinc in a separate line, in vacuum conditions and high temperature. The reduction process of the water was occurred not normally because in the inside of the glass balloons seems water droplets. The different experiments of the changes the water quantity, Zinc quantity, dimensions of the metallic Zinc and the temperature of the reduction reaction didn

  6. Carbon isotope ratio analysis of endogenous glucocorticoid urinary metabolites after cortisone acetate and adrenosterone administration for doping control.

    Science.gov (United States)

    Brooker, Lance; Cawley, Adam; Kazlauskas, Ray; Goebel, Catrin; George, Adrian

    2012-12-01

    Glucocorticoids are listed on the World Anti-Doping Agency (WADA) Prohibited List of substances. The detection of the administration of hydrocortisone and cortisone is complicated by the fact that the human body also produces these steroids naturally. Gas chromatography-combustion-isotope ratio mass spectrometry can be utilized to determine the use of endogenous glucocorticoids by measuring the carbon isotope ratio (CIR) of their resulting metabolites in human urine samples. A comprehensive sample preparation protocol for the analysis of endogenous glucocorticoid urinary metabolites was developed and validated, incorporating the use of high performance liquid chromatography (HPLC) for purification and chemical oxidation for derivatisation. Target compounds were tetrahydrocortisol and tetrahydrocortisone, and 11β-hydroxyetiocholanolone, 11-oxoetiocholanolone and 11β-hydroxyandrosterone, while pregnanediol functioned as the endogenous reference compound. Urine samples from a population of 50 volunteers were analyzed to determine CIR reference limits. Excretion studies of the endogenous glucocorticoid preparation cortisone acetate (25 mg oral) and the dietary supplement adrenosterone (75 mg oral) were conducted with six male individuals. Variable changes in steroid metabolite isotopic composition were found across subjects after administration. The study also revealed that CIR analysis of the major glucocorticoid metabolites tetrahydrocortisol and tetrahydrocortisone is necessary to unambiguously distinguish administration of cortisone and adrenosterone, the former officially restricted to out-of-competition use by athletes, the latter not being restricted at the current time. Moreover, this study reaffirms that CIR methods for the doping control of endogenous steroids should not rely upon a single ERC, as the administration of an appropriate precursor to that ERC could cause complications during analysis. PMID:22987608

  7. Modelling the Phanerozoic carbon cycle and climate - Constraints from the Sr-87/Sr-86 isotopic ratio of seawater

    Science.gov (United States)

    Francois, Louis M.; Walker, James C. G.

    1992-01-01

    A numerical model is developed for simulating the long-term changes of atmospheric CO2 and climate during the Phanerozoic. The model describes the coupled evolution of the biogeochemical cycles of C, S, Ca, Mg, P, and Sr, with the emphasis on the effect of coupling the cycles of carbon and strontium and on interpreting the observed seawater Sr-87/Sr-86 ratios. The abilities of continental weathering, volcanism, and surface lithology in generating that signal are tested and compared. The results obtained are used to reconstruct a history of atmospheric CO2 and climate during Phanerozoic time, consistent with the strontium isotopic data. It is shown that the predicted history is compatible with paleoclimatic indicators, such as the timing of glaciation and the estimates of Cretaceous paleotemperatures.

  8. Consistency of NMR and mass spectrometry determinations of natural-abundance site-specific carbon isotope ratios. The case of glycerol.

    Science.gov (United States)

    Zhang, B L; Trierweiler, M; Jouitteau, C; Martin, G J

    1999-07-01

    Quantitative determinations of natural-abundance carbon isotope ratios by nuclear magnetic resonance (SNIF-NMR) have been optimized by appropriate selection of the experimental conditions and by signal analysis based on a dedicated algorithm. To check the consistency of the isotopic values obtained by NMR and mass spectrometry (IRMS) the same glycerol samples have been investigated by both techniques. To have access to site-specific isotope ratios by IRMS, the products have been degraded and transformed into two derivatives, one of which contains carbons 1 and 3 and the other carbon 2 of glycerol. The sensitivity of the isotopic parameters determined by IRMS to fractionation effects possibly occurring in the course of the chemical transformations has been investigated, and the repeatability and reproducibility of both analytical chains have been estimated. The good agreement observed between the two series of isotopic results supports the reliability of the two different approaches. SNIF-NMR is therefore a very attractive tool for routine determination, in a single nondestructive experiment, of the carbon isotope distribution in glycerol, and the method can be applied to other compounds. Using this method, the isotopic distributions have been compared for glycerol samples, obtained from plant or animal oils, extracted from fermented media, or prepared by chemical synthesis. Typical behaviors are characterized. PMID:21662780

  9. On the interference of 86Kr2+ during carbon isotope analysis of atmospheric methane using continuous flow combustion – isotope ratio mass spectrometry

    Directory of Open Access Journals (Sweden)

    T. Röckmann

    2013-02-01

    Full Text Available Stable carbon isotope analysis of methane (δ13C of CH4 on atmospheric samples is one key method to constrain the current and past atmospheric CH4 budget. A frequently applied measurement technique is gas chromatography isotope ratio mass spectrometry coupled to a combustion-preconcentration unit. This report shows that the atmospheric trace gas krypton can severely interfere during the mass spectrometric measurement leading to significant biases in δ13C of CH4 if krypton is not sufficiently separated during the analysis. The effect comes about by the lateral tailing of the peak of doubly charged 86Kr in the neighbouring m/z, 44, 45, and 46 Faraday cups. Accordingly, the introduced bias is dependent on the chromatographic separation, the Kr to CH4 mixing ratio in the sample, the mass spectrometer source tuning as well as the detector configuration and can amount to up to several permil in δ13C. Apart from technical solutions to avoid this interference we present correction routines to a posteriori remove the bias.

  10. Shifts in bryophyte carbon isotope ratio across an elevation × soil age matrix on Mauna Loa, Hawaii: do bryophytes behave like vascular plants?

    OpenAIRE

    Waite, Mashuri; Sack, Lawren

    2011-01-01

    The carbon isotope ratio (δ13C) of vascular plant leaf tissue is determined by isotope discrimination, primarily mediated by stomatal and mesophyll diffusion resistances and by photosynthetic rate. These effects lead to predictable trends in leaf δ13C across natural gradients of elevation, irradiance and nutrient supply. Less is known about shifts in δ13C for bryophytes at landscape scale, as bryophytes lack stomata in the dominant gametophyte phase, and thus lack active control over CO2 diff...

  11. Carbon and nitrogen stable isotope ratios can estimate anionic polyacrylamide degradation in soil

    Science.gov (United States)

    Water soluble anionic polyacrylamide (PAM) is a highly effective erosion-preventing and infiltration-enhancing polymer, when applied at rates of 1 to 10 g/m-3 in furrow irrigation water. PAM degradation has not directly been measured in soil or water. Natural abundance of the carbon (13C/12C) isoto...

  12. Paleo-vegetation study using dating by 14 C and carbon isotope ratio

    International Nuclear Information System (INIS)

    Different approaches that include biological, geomorphological and botanical studies have been used to infer past climatic changes in the Amazon. Our approach involve the use of 13 C analyses in soil organic matter to infer past vegetation changes based on distinct isotopic composition that characterize C3 and C4 plants, and 14 C is used as dating tool, in two regions of natural Forest and Cerrado, located in Rondonia state. The soil at the Forest site is Podzolico Vermelho Amarelo and the Cerrado site is a Latosol Vermelho Amarelo. Radiocarbon analyses of total soil fraction samples indicate that the organic matter in these soils is at least Holocene in age δ13 C values for total soil organic matter in the forest varies from-28 at the surface to 25% at depth of 2 m, indicating the predominance of a C3 cycle in the last 3 270 yrs. At the Cerrado the δ13 C change from -21 to -14% in the first 30 cm characterizing C4 cycle and changed to -19% at 135 cm, probably characterizing a mixture between C3 and C4 plants and an increase to -16% is observed at 195 cm, again indicating a predominance of C4 plants. This data show that the Cerrado ecosystem was much more dynamics in term of vegetation changes than Forest. (author). 10 refs, 2 figs, 1 tab

  13. Compound-specific stable carbon isotope ratios of phenols and nitrophenols derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •For GCC–IRMS analysis, an approach avoiding impact of NO2 on δ13C was demonstrated. •Carbon isotope fractionations during derivatizing reactions here were negligible. •Except some labile compounds, the overall bias of the method here was −0.21‰. •Even for the labile compounds, measurement biases ranged +1.2‰ to −1.4‰. •Real sample analysis demonstrates usefulness of the method for fractionation study. -- Abstract: We developed an analytical method for measuring compound-specific stable carbon isotope ratios (δ13C) of phenols and nitrophenols in filter samples of particulate organic matter. The method was tested on 13 phenols derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), together with four nonphenolic compounds. The data obtained by our method required two specific corrections for the determination of valid δ13C values: (1) for nitro compounds, the routine correction with use of m/z 46 for the contribution of 12C17O16O molecules) to m/z 45 was modified due to impact of NO2 on the m/z 46 trace, and (2) for the derivatized phenols, measured δ13C values were corrected for the shift in δ13C due to the addition of carbon atoms from the BSTFA moiety. Analysis of standard-spiked filters showed that overall there was a small compound-dependent bias in the δ13C values: the average bias ± the standard error of the mean of −0.21 ± 0.1‰ for the standard compounds tested, except 3-methylcatechol, methylhydroquinone, 4-methyl-2-nitrophenol, and 2,6-dimethyl-4-nitrophenol, whereas the average biases ± the standard errors of the mean for those were +1.2 ± 0.3‰, +1.2 ± 0.2‰, −1.2 ± 0.2‰, and −1.4 ± 0.5‰, respectively, when the injected mass of a derivatized compound exceeded 15 ngC. In situations where such small biases and uncertainties are acceptable, the method described here could be used to obtain valuable information about δ13C values. We also analyzed a real filter

  14. Possible algal origin of long chain odd n-alkanes in immature sediments as revealed by distributions and carbon isotope ratios

    OpenAIRE

    Lichtfouse, Eric; Derenne., Sylvie; Mariotti, André; Largeau, Claude

    1994-01-01

    A Pliocene oil shale (Pula, Hungary), a C3 plant Triticum aestivum and a C4 plant Zea mays were compared using isotopic composition of bulk organic matter, along with distributions and individual carbon isotope ratios of n-alkanes from organic extracts. The microalga Botryococcus braunii (A race) was thus shown to be the main source of the predominant 27, 29 and 31 n-alkanes of Pula sediment Therefore, the dominance of odd carbon-numbered n-alkanes in the range C25–35 in extracts from immatur...

  15. Hydrogen and carbon isotopic ratios of polycyclic aromatic compounds in two CM2 carbonaceous chondrites and implications for prebiotic organic synthesis

    Science.gov (United States)

    Huang, Yongsong; Aponte, José C.; Zhao, Jiaju; Tarozo, Rafael; Hallmann, Christian

    2015-09-01

    Study of meteoritic organic compounds offers a unique opportunity to understand the origins of the organic matter in the early Solar System. Meteoritic polycyclic aromatic hydrocarbons (PAHs) and heteropolycyclic aromatic compounds (HACs) have been studied for over fifty years, however; their hydrogen stable isotopic ratios (δD) have never been reported. Compound-specific δD measurements of PAHs and HACs are important, in part because the carbon isotopic ratios (δ13C) of various meteoritic PAHs cannot be readily distinguished from their terrestrial counterparts and it is difficult to rule out terrestrial contamination based on carbon isotopic ratios alone. In this study, we have extracted and identified more than sixty PAHs and HACs present in two CM2 carbonaceous chondrites Murchison and LON 94101. Their carbon and hydrogen stable isotopic ratios (δ13C and δD) were measured and used to discuss about their synthetic environments and formation mechanisms. The concentration of aromatic compounds is ∼30% higher in Murchison than in the Antarctic meteorite LON 94101, but both samples contained similar suites of PAHs and HACs. All PAHs and HACs found exhibited positive δD values (up to 1100‰) consistent with an extraterrestrial origin, indicating the relatively low δ13C values are indeed an inherent feature of the meteoritic aromatic compounds. The hydrogen isotopic data suggest aromatic compounds in carbonaceous chondrites were mainly formed in the cold interstellar environments. Molecular level variations in hydrogen and carbon isotopic values offer new insights to the formation pathways for the aromatic compounds in carbonaceous chondrites.

  16. Variation in water use efficiency and leaf carbon isotope ratio in navy bean (Phaseolus vulgaris L.) with growth stages

    International Nuclear Information System (INIS)

    Full text: One pot culture experiment was carried out to determine if leaf carbon isotope ratio and water use efficiency (WUE) in four genotypes of navy bean (BAT 477, DOR364, BAT881 and G21212) change with growth stages (initial flowering, peak flowering and fruit growth). One set of pots were irrigated regularly to 85% field capacity (well watered) and other set was maintained at 35% field capacity (water stressed). Plants were monitored for water-use and leaf 13C (13C/12C expressed with a differential notation as 13C ). The leaf 13C values decreased from initial flowering to fruit growth stage in both well watered and water stressed treatments. This result suggests that carbon might have been relocated as the plants advanced in growth. The differences between initial flowering and fruit growth stage, and between peak flowering and fruit growth were significant (p13C and WUE, and there were no significant genotype x growth stage interactions. There was a positive correlation between WUE and above ground dry matter (AGDM) across genotypes, and a good relationship (r=0.74*) between WUE and specific leaf area (cm2/g) was found at initial flowering. These results support the hypothesis that a higher WUE for the four genotypes of navy bean was achieved by higher photosynthetic capacity. Significant differences in leaf 13C were also noted between the well watered and water stressed plants. Well watered plants maintained a correlation between leaf 13C and WUE (r=0.92* 0.67* and 0.51* at initial flowering, peak flowering and fruit growth stage, respectively), but no such correlation was found for water stressed plants. Based on these results we conclude that (i) WUE of navy bean genotypes can best be assessed by determining leaf 13C of well watered plants at initial flowering stage and (ii) leaf 13C was not a promising indicator of adaptation to water deficit in navy beans

  17. Transpiration efficiency over an annual cycle, leaf gas exchange and wood carbon isotope ratio of three tropical tree species.

    Science.gov (United States)

    Cernusak, Lucas A; Winter, Klaus; Aranda, Jorge; Virgo, Aurelio; Garcia, Milton

    2009-09-01

    Variation in transpiration efficiency (TE) and its relationship with the stable carbon isotope ratio of wood was investigated in the saplings of three tropical tree species. Five individuals each of Platymiscium pinnatum (Jacq.) Dugand, Swietenia macrophylla King and Tectona grandis Linn. f. were grown individually in large (760 l) pots over 16 months in the Republic of Panama. Cumulative transpiration was determined by repeatedly weighing the pots with a pallet truck scale. Dry matter production was determined by destructive harvest. The TE, expressed as experiment-long dry matter production divided by cumulative water use, averaged 4.1, 4.3 and 2.9 g dry matter kg(-1) water for P. pinnatum, S. macrophylla and T. grandis, respectively. The TE of T. grandis was significantly lower than that of the other two species. Instantaneous measurements of the ratio of intercellular to ambient CO(2) partial pressures (c(i)/c(a)), taken near the end of the experiment, explained 66% of variation in TE. Stomatal conductance was lower in S. macrophylla than in T. grandis, whereas P. pinnatum had similar stomatal conductance to T. grandis, but with a higher photosynthetic rate. Thus, c(i)/c(a) and TE appeared to vary in response to both stomatal conductance and photosynthetic capacity. Stem-wood delta(13)C varied over a relatively narrow range of just 2.2 per thousand, but still explained 28% of variation in TE. The results suggest that leaf-level processes largely determined variation among the three tropical tree species in whole-plant water-use efficiency integrated over a full annual cycle. PMID:19661136

  18. Source identification of particulate organic matter in view of land uses in Shingil Creek using carbon, nitrogen and oxygen isotope ratios.

    Science.gov (United States)

    Kim, Dahae; Lee, Yeonjung; Ock, Giyoung; Kang, Sujin; Kim, Minseob; Choi, Jongwoo; Shin, Kyung-Hoon

    2016-04-01

    Anthropogenic inputs influence the quality and quantity of organic matter, which is important for recycling of nutrients and chemical elements. Stable isotope techniques are useful for distinguishing the origin of organic matter by using the characteristics that are distinctive between sources. Artificial Lake Shihwa, especially the Shingil creek is typically under the strong anthropogenic pressure with continuous continental inputs from various sources. Hence in this study, the characteristics and sources of organic matter in water and surface sediment of the Shingil creeks in the rural, urban, and industrial areas were evaluated by using carbon, nitrogen and oxygen isotope ratios, by analyzing samples collected during the rainy season and dry season. Among the input sources, the organic matter derived from industrial regions showed distinct nitrogen isotope values compared to other sites. Further studies including other techniques such as hydrogen isotope will provide an insight into the development of a strategy for effective water quality management in Lake Shihwa

  19. Carbon and nitrogen stable isotope ratios and mercury concentration in the scalp hair of residents from Taiji, a whaling town

    International Nuclear Information System (INIS)

    Highlights: ► We analyzed δ13C, δ15N and Hg in hair from Japanese whale meat-eaters and non-eaters. ► The δ15N and δ13C values in whale meat-eaters were higher than those in non-eaters. ► The Hg concentration in whale meat-eaters was higher than that in non-eaters. ► A positive correlation was seen between δ15N and Hg in whale meat-eaters. ► Consumption of whale meat may increase δ15N, δ13C and Hg in the scalp hair. -- Abstract: We analyzed stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) as well as mercury (Hg) concentration in the scalp hair of Japanese who consumed whale meat and those who did not, and investigated the relationships among the δ13C and δ15N values and Hg concentration. The average δ15N and δ13C values of whale meat-eaters (10.11‰ and −18.5‰) were significantly higher than those of non-eaters (9.28‰ and −18.9‰), respectively. The average Hg concentration of whale meat-eaters (20.6 μg/g) was significantly higher than that of non-eaters (2.20 μg/g). Significant positive correlations were found between the δ13C and δ15N values and between the δ15N value and Hg concentration in the hair of whale meat-eaters, while the correlation between the δ15N value and Hg concentration was not statistically significant in the non-eaters. The consumption of whale meat may increase Hg concentration as well as δ15N and δ13C values in scalp hair

  20. Organic Reference Materials for Hydrogen, Carbon, and Nitrogen Stable Isotope-Ratio Measurements: Caffeines, n-Alkanes, Fatty Acid Methyl Esters, Glycines, l-Valines, Polyethylenes, and Oils.

    Science.gov (United States)

    Schimmelmann, Arndt; Qi, Haiping; Coplen, Tyler B; Brand, Willi A; Fong, Jon; Meier-Augenstein, Wolfram; Kemp, Helen F; Toman, Blaza; Ackermann, Annika; Assonov, Sergey; Aerts-Bijma, Anita T; Brejcha, Ramona; Chikaraishi, Yoshito; Darwish, Tamim; Elsner, Martin; Gehre, Matthias; Geilmann, Heike; Gröning, Manfred; Hélie, Jean-François; Herrero-Martín, Sara; Meijer, Harro A J; Sauer, Peter E; Sessions, Alex L; Werner, Roland A

    2016-04-19

    An international project developed, quality-tested, and determined isotope-δ values of 19 new organic reference materials (RMs) for hydrogen, carbon, and nitrogen stable isotope-ratio measurements, in addition to analyzing pre-existing RMs NBS 22 (oil), IAEA-CH-7 (polyethylene foil), and IAEA-600 (caffeine). These new RMs enable users to normalize measurements of samples to isotope-δ scales. The RMs span a range of δ(2)HVSMOW-SLAP values from -210.8 to +397.0 mUr or ‰, for δ(13)CVPDB-LSVEC from -40.81 to +0.49 mUr and for δ(15)NAir from -5.21 to +61.53 mUr. Many of the new RMs are amenable to gas and liquid chromatography. The RMs include triads of isotopically contrasting caffeines, C16 n-alkanes, n-C20-fatty acid methyl esters (FAMEs), glycines, and l-valines, together with polyethylene powder and string, one n-C17-FAME, a vacuum oil (NBS 22a) to replace NBS 22 oil, and a (2)H-enriched vacuum oil. A total of 11 laboratories from 7 countries used multiple analytical approaches and instrumentation for 2-point isotopic normalization against international primary measurement standards. The use of reference waters in silver tubes allowed direct normalization of δ(2)H values of organic materials against isotopic reference waters following the principle of identical treatment. Bayesian statistical analysis yielded the mean values reported here. New RMs are numbered from USGS61 through USGS78, in addition to NBS 22a. Because of exchangeable hydrogen, amino acid RMs currently are recommended only for carbon- and nitrogen-isotope measurements. Some amino acids contain (13)C and carbon-bound organic (2)H-enrichments at different molecular sites to provide RMs for potential site-specific isotopic analysis in future studies. PMID:26974360

  1. Stable Isotope Ratios and Forensic Analysis of Microorganisms▿

    OpenAIRE

    Kreuzer-Martin, Helen W.; Jarman, Kristin H.

    2007-01-01

    In the aftermath of the anthrax letters of 2001, researchers have been exploring various analytical signatures for the purpose of characterizing the production environment of microorganisms. One such signature is stable isotope ratios, which in heterotrophs, are a function of nutrient and water sources. Here we discuss the use of stable isotope ratios in microbial forensics, using as a database the carbon, nitrogen, oxygen, and hydrogen stable isotope ratios of 247 separate cultures of Bacill...

  2. Carbon and nitrogen stable isotope ratios analysis of food sources for Chironomus acerbiphilus larvae (Diptera Chironomidae) in strongly acidic lake Katanuma

    Energy Technology Data Exchange (ETDEWEB)

    Doi, Hideyuki [Tohoku Univ., Sendai (Japan). Graduate School of Science; Kikuchi, Eisuke; Shikano, Shuichi

    2001-12-01

    The food sources for Chironomus acerbiphilus larvae (Diptera Chironomidae) were analyzed using carbon and nitrogen stable isotope ratios in Lake Katanuma. Lake Katanuma is a volcanic and strongly acidic lake (average pH 2.2). In Lake Katanuma, potential sources of diets for the chironomid larvae are limited including a benthic diatom (Pinnularia braunii), a phytoplankton (Chlamydomonas acidophila), sulfate oxidizing bacteria, and vascular plants supplied from vegetation surrounding the lake. Based on the average carbon and nitrogen isotope ratios among these potential sources and sediment, benthic diatoms were considered to be most probable food source of the chironomid larvae. {delta}{sup 13}C values of the chironomid were significantly different among seasons and habitat depths, suggesting that diet of C. acerbiphilus changed seasonally and with habitat depth. (author)

  3. Carbon and nitrogen stable isotope ratios analysis of food sources for Chironomus acerbiphilus larvae (Diptera Chironomidae) in strongly acidic lake Katanuma

    International Nuclear Information System (INIS)

    The food sources for Chironomus acerbiphilus larvae (Diptera Chironomidae) were analyzed using carbon and nitrogen stable isotope ratios in Lake Katanuma. Lake Katanuma is a volcanic and strongly acidic lake (average pH 2.2). In Lake Katanuma, potential sources of diets for the chironomid larvae are limited including a benthic diatom (Pinnularia braunii), a phytoplankton (Chlamydomonas acidophila), sulfate oxidizing bacteria, and vascular plants supplied from vegetation surrounding the lake. Based on the average carbon and nitrogen isotope ratios among these potential sources and sediment, benthic diatoms were considered to be most probable food source of the chironomid larvae. δ13C values of the chironomid were significantly different among seasons and habitat depths, suggesting that diet of C. acerbiphilus changed seasonally and with habitat depth. (author)

  4. The CN isotopic ratios in comets

    Science.gov (United States)

    Manfroid, J.; Jehin, E.; Hutsemékers, D.; Cochran, A.; Zucconi, J.-M.; Arpigny, C.; Schulz, R.; Stüwe, J. A.; Ilyin, I.

    2009-08-01

    Our aim is to determine the isotopic ratios 12C/13C and 14N/15N in a variety of comets and link these measurements to the formation and evolution of the solar system. The 12C/13C and 14N/15N isotopic ratios are measured for the CN radical by means of high-resolution optical spectra of the R branch of the B-X (0, 0) violet band. 23 comets from different dynamical classes have been observed, sometimes at various heliocentric and nucleocentric distances, in order to estimate possible variations of the isotopic ratios in parent molecules. The 12C/13C and 14N/15N isotopic ratios in CN are remarkably constant (average values of, respectively, 91.0 ± 3.6 and 147.8 ± 5.7) within our measurement errors, for all comets whatever their origin or heliocentric distance. While the carbon isotopic ratio does agree with the terrestrial value (89), the nitrogen ratio is a factor of two lower than the terrestrial value (272), indicating a fractionation in the early solar system, or in the protosolar nebula, common to all the comets of our sample. This points towards a common origin of the comets independently of their birthplaces, and a relationship between HCN and CN. Appendices and Table [see full textsee full textsee full text] are only available in electronic form at http://www.aanda.org Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programmes ID 268.C-5570, 270.C-5043, 073.C-0525, 274.C-5015 and 075.C-0355(A).

  5. Boron isotope ratio determination in carbonates /via/ LA-MC-ICP-MS using soda-lime glass standards as reference material

    OpenAIRE

    Fietzke, Jan; Heinemann, Agnes; Taubner, Isabelle; Böhm, Florian; Erez, Jonathan; Eisenhauer, Anton

    2010-01-01

    A new in situ method using LA-MC-ICP-MS (193 nm excimer laser) for the determination of stable boron isotope ratios (δ11B) in carbonates was developed. Data were acquired via a standard sample standard bracketing procedure typically providing a reproducibility of 0.5‰ (SD) for samples containing 35 ppm of boron. A single ablation interval consumed about 5 µg of sample corresponding to about 0.2 ng of boron. The major finding was the similar instrumental fractionation behaviour of carbonates, ...

  6. An analytical system for studying the stable isotopes of carbon monoxide using continuous flow-isotope ratio mass spectrometry (CF-IRMS)

    OpenAIRE

    S. L. Pathirana; C. van der Veen; Popa, M. E.; T. Röckmann

    2015-01-01

    In the atmosphere, carbon monoxide (CO) is the major sink for the hydroxyl radical (OH •), has multiple anthropogenic and natural sources and considerable spatial and seasonal variability. Measurements of CO isotopic composition are useful in constraining the strengths of its individual source and sink processes and thus its global cycle. A fully automated system for δ13C and δ18O analysis has been developed to extract CO from an air sample, convert ...

  7. Carbon isotope techniques

    International Nuclear Information System (INIS)

    This book is a hands-on introduction to using carbon isotope tracers in experimental biology and ecology. It is a bench-top reference with protocols for the study of plants, animals, and soils. The 11C, 12C, 13C, and 14C carbon isotopes are considered and standard techniques are described by established authors. The compilation includes the following features: specific, well-established, user-oriented techniques; carbon cycles in plants, animals, soils, air, and water; isotopes in ecological research; examples and sample calculations

  8. Carbon isotopes in mollusk shell carbonates

    Science.gov (United States)

    McConnaughey, Ted A.; Gillikin, David Paul

    2008-10-01

    Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod shell carbonates. Land snails construct their shells mainly from respired CO2, and shell δ13C reflects the local mix of C3 and C4 plants consumed. Shell δ13C is typically >10‰ heavier than diet, probably because respiratory gas exchange discards CO2, and retains the isotopically heavier HCO3 -. Respired CO2 contributes less to the shells of aquatic mollusks, because CO2/O2 ratios are usually higher in water than in air, leading to more replacement of respired CO2 by environmental CO2. Fluid exchange with the environment also brings additional dissolved inorganic carbon (DIC) into the calcification site. Shell δ13C is typically a few ‰ lower than ambient DIC, and often decreases with age. Shell δ13C retains clues about processes such as ecosystem metabolism and estuarine mixing. Ca2+ ATPase-based models of calcification physiology developed for corals and algae likely apply to mollusks, too, but lower pH and carbonic anhydrase at the calcification site probably suppress kinetic isotope effects. Carbon isotopes in biogenic carbonates are clearly complex, but cautious interpretation can provide a wealth of information, especially after vital effects are better understood.

  9. Study and validity of 13C stable carbon isotopic ratio analysis by mass spectrometry and 2H site-specific natural isotopic fractionation by nuclear magnetic resonance isotopic measurements to characterize and control the authenticity of honey

    International Nuclear Information System (INIS)

    Honey samples were analyzed by stable carbon isotopic ratio analysis by mass spectrometry (SCIRA-MS) and site-specific natural isotopic fractionation measured by nuclear magnetic resonance (SNIF-NMR) to first determine their potentials for characterizing the substance and then to combat adulteration. Honey samples from several geographic and botanical origins were analyzed. The δ 13C parameter was not significant for characterizing an origin, while the (D/H)I ratio could be used to differentiate certain single-flower varieties. Application of the official control method of adding a C4 syrup (AOAC official method 998.12) to our authentic samples revealed anomalies resulting from SCIRA indices that were more negative than -1 per mille (permil). A filtration step was added to the experimental procedure and provided results that were compliant with Natural origin of our honey samples. In addition, spiking with a C4 syrup could be detected starting at 9-10%. The use of SNIF-NMR is limited by the detection of a syrup spike starting only at 20%, which is far from satisfying

  10. Study and validity of {sup 13}C stable carbon isotopic ratio analysis by mass spectrometry and {sup 2}H site-specific natural isotopic fractionation by nuclear magnetic resonance isotopic measurements to characterize and control the authenticity of honey

    Energy Technology Data Exchange (ETDEWEB)

    Cotte, J.F. [Cooperative France Miel, BP 5, 330 Mouchard (France); Casabianca, H. [Service Central d' Analyse, USR 059-CNRS, BP 22, 69390 Vernaison (France); Lheritier, J. [Cooperative France Miel, BP 5, 330 Mouchard (France); Perrucchietti, C. [Service Central d' Analyse, USR 059-CNRS, BP 22, 69390 Vernaison (France); Sanglar, C. [Service Central d' Analyse, USR 059-CNRS, BP 22, 69390 Vernaison (France); Waton, H. [Service Central d' Analyse, USR 059-CNRS, BP 22, 69390 Vernaison (France); Grenier-Loustalot, M.F. [Service Central d' Analyse, USR 059-CNRS, BP 22, 69390 Vernaison (France)]. E-mail: mf.grenier-loustalot@sca.cnrs.fr

    2007-01-16

    Honey samples were analyzed by stable carbon isotopic ratio analysis by mass spectrometry (SCIRA-MS) and site-specific natural isotopic fractionation measured by nuclear magnetic resonance (SNIF-NMR) to first determine their potentials for characterizing the substance and then to combat adulteration. Honey samples from several geographic and botanical origins were analyzed. The {delta} {sup 13}C parameter was not significant for characterizing an origin, while the (D/H){sub I} ratio could be used to differentiate certain single-flower varieties. Application of the official control method of adding a C{sub 4} syrup (AOAC official method 998.12) to our authentic samples revealed anomalies resulting from SCIRA indices that were more negative than -1 per mille (permil). A filtration step was added to the experimental procedure and provided results that were compliant with Natural origin of our honey samples. In addition, spiking with a C{sub 4} syrup could be detected starting at 9-10%. The use of SNIF-NMR is limited by the detection of a syrup spike starting only at 20%, which is far from satisfying.

  11. Study and validity of 13C stable carbon isotopic ratio analysis by mass spectrometry and 2H site-specific natural isotopic fractionation by nuclear magnetic resonance isotopic measurements to characterize and control the authenticity of honey.

    Science.gov (United States)

    Cotte, J F; Casabianca, H; Lhéritier, J; Perrucchietti, C; Sanglar, C; Waton, H; Grenier-Loustalot, M F

    2007-01-16

    Honey samples were analyzed by stable carbon isotopic ratio analysis by mass spectrometry (SCIRA-MS) and site-specific natural isotopic fractionation measured by nuclear magnetic resonance (SNIF-NMR) to first determine their potentials for characterizing the substance and then to combat adulteration. Honey samples from several geographic and botanical origins were analyzed. The delta(13)C parameter was not significant for characterizing an origin, while the (D/H)(I) ratio could be used to differentiate certain single-flower varieties. Application of the official control method of adding a C(4) syrup (AOAC official method 998.12) to our authentic samples revealed anomalies resulting from SCIRA indices that were more negative than -1 per thousand (permil). A filtration step was added to the experimental procedure and provided results that were compliant with the natural origin of our honey samples. In addition, spiking with a C(4) syrup could be detected starting at 9-10%. The use of SNIF-NMR is limited by the detection of a syrup spike starting only at 20%, which is far from satisfying. PMID:17386484

  12. Recent development in isotope ratio mass spectrometry

    International Nuclear Information System (INIS)

    Within the limited of this review the following topics will be briefly discussed: a) Accuracy, precision, internal relative standard deviation (RISD) and external relative standard deviation (RESD) of isotope ratio measurements. With advanced instrumentation and use of standard reference materials, high accuracy and RESD = 0.002% (or better) may be achieved; b) The advantages of modern automatic isotope ratio mass spectrometer are briefly described. Computer controlled operation and data acquisition, and multiple ion collection are the recent important improvement; c) The isotopic fractionation during the course of isotope ratio measurement is considered as a major source of errors in thermal ionization of metallic elements. The phenomenon in strontium, neodymium, uranium, lead and calcium and methods to correct the measured data are discussed; d) Applications of isotope ratio mass spectrometry in atomic weight determinations, the isotope dilution technique, isotope geology, and isotope effects in biological systems are described together with specific applications in various research and technology area. (author)

  13. Isotope ratio mass spectrometry in oceanic studies

    International Nuclear Information System (INIS)

    Isotope ratio mass spectrometry (IRMS) is an important and well established method in many scientific fields as analytical chemistry (isotope dilution MS), physical chemistry, nuclear sciences and technology, environmental, agricultural, geological isotope dating, archaeometric, cosmic, bioavailability and nutrition studies, food authentication and adulteration control, elucidation of chemical reaction mechanism, isotope effect studies on chemical reactions and isotope enrichment/separation processes. This paper is aimed to provide a brief summary of IRMS contribution to sea and oceanic studies

  14. Organic Reference Materials for Hydrogen, Carbon, and Nitrogen Stable Isotope-Ratio Measurements: Caffeines, n-Alkanes, Fatty Acid Methyl Esters, Glycines, L-Valines, Polyethylenes, and Oils

    OpenAIRE

    Schimmelmann, Arndt; Qi, Haiping; Coplen, Tyler B.; Brand, Willi A.; Fong, Jon; Meier-Augenstein, Wolfram; Kemp, Helen F.; Toman, Blaza; Ackermann, Annika; Assonov, Sergey; Aerts-Bijma, Anita T.; Brejcha, Ramona; Chikaraishi, Yoshito; Darwish, Tamim; Elsner, Martin

    2016-01-01

    An international project developed, quality-tested, and determined isotope−δ values of 19 new organic reference materials (RMs) for hydrogen, carbon, and nitrogen stable isotope-ratio measurements, in addition to analyzing pre-existing RMs NBS 22 (oil), IAEA-CH-7 (polyethylene foil), and IAEA-600 (caffeine). These new RMs enable users to normalize measurements of samples to isotope−δ scales. The RMs span a range of δ^2H_(VSMOW-SLAP) values from −210.8 to +397.0 mUr or ‰, for δ^(13)C_(VPDB-LSV...

  15. Combined Stable Carbon Isotope and C/N Ratios as Indicators of Source and Fate of Organic Matter in the Bangpakong River Estuary, Thailand

    Directory of Open Access Journals (Sweden)

    Thanomsak Boonphakdee

    2008-01-01

    Full Text Available Stable carbon isotopes and C/N ratios of particulate organic matter (POM in suspended solids and surficial sediment were used to define the spatial and temporal variability in an anthropogenic tropical river estuary, the Bangpakong River Estuary. Samples were taken along salinity gradients during the four different river discharges in the beginning, high river discharge and at the end of the wet season, and low river discharge during the dry season. The values of [C/N]a ratio and d13C in the river estuary revealed significant differences from those of the offshore station. Conservative behaviors of [C/N]a and d13C in the estuary during the wet season indicated major contribution of terrigenous C3 plants derived OM. By contrast, during the dry season, marine input mainly dominated OM contribution with an evidence of anthropogenic input to the estuary. These compositions of the bulk sedimentary OM were dominated by paddy rice soils and marine derived OM during the wet and dry seasons, respectively. These results show that the combined stable carbon isotopes and C/N ratios can be used to identify the source and fate of OM even in a river estuary. This tool will be useful to achieve sustainable management in coastal zone.

  16. Source inference of exogenous gamma-hydroxybutyric acid (GHB) administered to humans by means of carbon isotopic ratio analysis: novel perspectives regarding forensic investigation and intelligence issues.

    Science.gov (United States)

    Marclay, François; Saudan, Christophe; Vienne, Julie; Tafti, Mehdi; Saugy, Martial

    2011-05-01

    γ-Hydroxybutyric acid (GHB) is an endogenous short-chain fatty acid popular as a recreational drug due to sedative and euphoric effects, but also often implicated in drug-facilitated sexual assaults owing to disinhibition and amnesic properties. Whilst discrimination between endogenous and exogenous GHB as required in intoxication cases may be achieved by the determination of the carbon isotope content, such information has not yet been exploited to answer source inference questions of forensic investigation and intelligence interests. However, potential isotopic fractionation effects occurring through the whole metabolism of GHB may be a major concern in this regard. Thus, urine specimens from six healthy male volunteers who ingested prescription GHB sodium salt, marketed as Xyrem(®), were analysed by means of gas chromatography/combustion/isotope ratio mass spectrometry to assess this particular topic. A very narrow range of δ(13)C values, spreading from -24.81‰ to -25.06‰, was observed, whilst mean δ(13)C value of Xyrem(®) corresponded to -24.99‰. Since urine samples and prescription drug could not be distinguished by means of statistical analysis, carbon isotopic effects and subsequent influence on δ(13)C values through GHB metabolism as a whole could be ruled out. Thus, a link between GHB as a raw matrix and found in a biological fluid may be established, bringing relevant information regarding source inference evaluation. Therefore, this study supports a diversified scope of exploitation for stable isotopes characterized in biological matrices from investigations on intoxication cases to drug intelligence programmes. PMID:21455654

  17. The Roles of Sphagnum and Cyperaceae in the Methane Cycle of an Ombrotrophic Bog Revealed by the Carbon Isotope Ratios of Leaf Waxes

    Science.gov (United States)

    Isles, P. D.; Nichols, J. E.; Peteet, D. M.; Kenna, T. C.

    2011-12-01

    Methane is a strong greenhouse gas, and the role of the terrestrial carbon cycle in the concentrations of atmospheric methane is poorly understood. What is clear, is that northern peatlands are a significant source of methane to the atmosphere. A recent discovery, and a topic of much scrutiny, has been the relationship between Sphagnum in peatlands and symbiotic methanotrophic bacteria. These bacteria oxidize methane produced at depth in peatlands before it is released to the atmosphere, contributing 13C-depleted CO2 to Sphagnum photosynthate. We seek to better understand the fate of methane produced in peatlands at depth, and the relationship between methane release from peatland surfaces and parameters such as temperature, moisture, and vegetation type. We compare carbon isotope ratios of leaf wax n-alkanes from sphagnum and vascular plants and major element chemistry at three different microhabitats, hummock, hollow, and sedge tussock, in Mer Bleue an ombrotrophic peatland near Ottowa, Ontario, Canada. We use these compound-specific carbon isotope measurements to constrain the amount of methane-derived CO2 incorporated by Sphagnum. We also compare our multiannually resolved down-core measurements to data from long-term monitoring of climate parameters and methane flux from the same microhabitats to ground-truth our sedimentary signature of methane with instrumental measurements.

  18. The last 41.000 years fluctuation in atmospheric CO2 concentration inferred from the changes in oxygen and carbon stable isotopes ratios of marine sediments

    International Nuclear Information System (INIS)

    The past atmospheric CO2 concentrations were reconstructed based on the results of measurements of stable oxygen and carbon isotopic ratios of fossil foraminifera and total organic carbon contained in marine sediment taken from the Okinawa Trough. East China Sea. In' this study, we utilized two models of Popp et al and Rau et al, for the reconstruction. The results show that the whole trends of the changes in CO2 concentrations are very similar, even when it is compared to the atmospheric CO2 concentration of air trapped in ice core from southern pole. Changes in atmospheric CO2 concentrations are interpreted as a consequence of fluctuation in ocean surface water utilization of CO2 by marine organism and those are closely related to glacial interglacial (cold-warm) fluctuations between maximum and minimum values through most Quaternary. (author)

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

    International Nuclear Information System (INIS)

    Full text: Seasonal variation in δ13C and δ18O of cellulose from annual rings of Pinus radiata growing at each of three sites in New Zealand was measured. The three sites differed in annual water balance, temperature, and vapour pressure deficit, and these differences were reflected in cellulose δ13C and δ18O. Specific events such as drought or heavy rain were recorded as peaks and troughs in enrichment. A canopy-level combined photosynthesis and conductance model was linked to a model of soil water content and δ18O of xylem water to allow daily prediction of δ13C and δ18O of cellulose. A photosynthesis-weighted average of δ13C and δ18O was calculated for each sampling period. Each sample represented between 3 and 30 days, depending on stem growth rate. The timing and amplitude of changes in δ13C were predicted accurately by the model, while general seasonal patterns and event related peaks in δ18O enrichment were well predicted. These results suggest that stable isotope ratios of cellulose from annual rings reflect the canopy response to interactions between site-specific and seasonal variation in climatic conditions and soil water availability

  20. Isotope analytics for the evaluation of the feeding influence on the isotope ratio in beef samples

    International Nuclear Information System (INIS)

    Information about the origin of food and associated production systems has a high significance for food control. An extremely promising approach to obtain such information is the determination of isotope ratios of different elements. In this study the correlation of the isotope ratios C-13/C-12, N-15/N-14, Mg-25/Mg-24, and Sr-87/Sr-86 in bovine samples (milk and urine) and the corresponding isotope ratios in feed was investigated. It was shown that in the bovine samples all four isotope ratios correlate with the isotope composition of the feed. The isotope ratios of strontium and magnesium have the advantage that they directly reflect the isotope ratios of the ingested feed since there is no isotope fractionation in the bovine organism which is in contrast to the case of carbon and nitrogen isotope ratios. From the present feeding study it is evident, that a feed change leads to a significant change in the delta C-13 values in milk and urine within 10 days already. For the deltaN-15 values the feed change was only visible in the bovine urine after 49 days. Investigations of cows from two different regions (Berlin/Germany and Goestling/Austria) kept at different feeding regimes revealed no differences in the N-15/N-14 and Mg-26/Mg-24 isotope ratios. The strongest correlation between the isotope ratio of the bovine samples and the kind of ingested feed was observed for the carbon isotope ratio. With this ratio even smallest differences in the feed composition were traceable in the bovine samples. Since different regions usually coincide with different feeding regimes, carbon isotope ratios can be used to distinguish bovine samples from different regions if the delta C-13 values of the ingested feed are different. Furthermore, the determination of strontium isotope ratios revealed significant differences between bovine and feed samples of Berlin and Goestling due to the different geologic realities. Hence the carbon and strontium isotope ratios allow the best

  1. Carbon and nitrogen stable isotope ratios of pelagic zooplankton elucidate ecohydrographic features in the oligotrophic Red Sea

    KAUST Repository

    Kürten, Benjamin

    2015-11-10

    Although zooplankton occupy key roles in aquatic biogeochemical cycles, little is known about the pelagic food web and trophodynamics of zooplankton in the Red Sea. Natural abundance stable isotope analysis (SIA) of carbon (δ13C) and N (δ15N) is one approach to elucidating pelagic food web structures and diet assimilation Integrating the combined effects of ecological processes and hydrography, ecohydrographic features often translate into geographic patterns in δ13C and δ15N values at the base of food webs. This is due, for example, to divergent 15N abundances in source end-members (deep water sources: high δ15N, diazotrophs: low δ15N). Such patterns in the spatial distributions of stable isotope values were coined isoscapes. Empirical data of atmospheric, oceanographic, and biological processes, which drive the ecohydrographic gradients of the oligotrophic Red Sea, are under-explored and some rather anticipated than proven. Specifically, five processes underpin Red Sea gradients: a) monsoon-related intrusions of nutrient-rich Indian Ocean water; b) basin scale thermohaline circulation; c) mesoscale eddy activity that causes up-welling of deep water nutrients into the upper layer; d) the biological fixation of atmospheric nitrogen (N2) by diazotrophs; and e) the deposition of aerosol-derived N. This study assessed relationships between environmental samples (nutrients, chlorophyll a), oceanographic data (temperature, salinity, current velocity [ADCP]), particulate organic matter (POM), and net-phytoplankton, with the δ13C and δ15N values of zooplankton collected in spring 2012 from 16°28’ to 26°57’N along the central axis of the Red Sea. The δ15N of bulk POM and most zooplankton taxa increased from North (Duba) to South (Farasan). The potential contribution of deep water nutrient-fueled phytoplankton, POM, and diazotrophs varied among sites. Estimates suggested higher diazotroph contributions in the North, a greater contribution of POM in the South

  2. Carbon and nitrogen stable isotope ratios of pelagic zooplankton elucidate ecohydrographic features in the oligotrophic Red Sea

    Science.gov (United States)

    Kürten, Benjamin; Al-Aidaroos, Ali M.; Kürten, Saskia; El-Sherbiny, Mohsen M.; Devassy, Reny P.; Struck, Ulrich; Zarokanellos, Nikolaos; Jones, Burton H.; Hansen, Thomas; Bruss, Gerd; Sommer, Ulrich

    2016-01-01

    Although zooplankton occupy key roles in aquatic biogeochemical cycles, little is known about the pelagic food web and trophodynamics of zooplankton in the Red Sea. Natural abundance stable isotope analysis (SIA) of carbon (δ13C) and N (δ15N) is one approach to elucidating pelagic food web structures and diet assimilation. Integrating the combined effects of ecological processes and hydrography, ecohydrographic features often translate into geographic patterns in δ13C and δ15N values at the base of food webs. This is due, for example, to divergent 15N abundances in source end-members (deep water sources: high δ15N, diazotrophs: low δ15N). Such patterns in the spatial distributions of stable isotope values were coined isoscapes. Empirical data of atmospheric, oceanographic, and biological processes, which drive the ecohydrographic gradients of the oligotrophic Red Sea, are under-explored and some rather anticipated than proven. Specifically, five processes underpin Red Sea gradients: (a) monsoon-related intrusions of nutrient-rich Indian Ocean water; (b) basin scale thermohaline circulation; (c) mesoscale eddy activity that causes up-welling of deep water nutrients into the upper layer; (d) the biological fixation of atmospheric nitrogen (N2) by diazotrophs; and (e) the deposition of dust and aerosol-derived N. This study assessed relationships between environmental samples (nutrients, chlorophyll a), oceanographic data (temperature, salinity, current velocity [ADCP]), particulate organic matter (POM), and net-phytoplankton, with the δ13C and δ15N values of zooplankton collected in spring 2012 from 16°28‧ to 26°57‧N along the central axis of the Red Sea. The δ15N of bulk POM and most zooplankton taxa increased from North (Duba) to South (Farasan). The potential contribution of deep water nutrient-fueled phytoplankton, POM, and diazotrophs varied among sites. Estimates suggested higher diazotroph contributions in the North, a greater contribution of

  3. Isotope Ratio Monitoring Gas Chromatography Mass Spectrometry (IRM-GCMS)

    International Nuclear Information System (INIS)

    On Earth, the C-13 content of organic compounds is depleted by roughly 13 to 23 permil from atmospheric carbon dioxide. This difference is largely due to isotope effects associated with the fixation of inorganic carbon by photosynthetic organisms. If life once existed on Mars, then it is reasonable to expect to observe a similar fractionation. Although the strongly oxidizing conditions on the surface of Mars make preservation of ancient organic material unlikely, carbon-isotope evidence for the existence of life on Mars may still be preserved. Carbon depleted in C-13 could be preserved either in organic compounds within buried sediments, or in carbonate minerals produced by the oxidation of organic material. A technique is introduced for rapid and precise measurement of the C-13 contents of individual organic compounds. A gas chromatograph is coupled to an isotope-ratio mass spectrometer through a combustion interface, enabling on-line isotopic analysis of isolated compounds. The isotope ratios are determined by integration of ion currents over the course of each chromatographic peak. Software incorporates automatic peak determination, corrections for background, and deconvolution of overlapped peaks. Overall performance of the instrument was evaluated by the analysis of a mixture of high purity n-alkanes of know isotopic composition. Isotopic values measured via IRM-GCMS averaged withing 0.55 permil of their conventionally measured values

  4. Isotopic ratios in the solar system

    International Nuclear Information System (INIS)

    This colloquium is aimed at presentation of isotope ratio measurements in different objects of solar system and surrounding interstellar space and evaluation of what information on composition and structure of primitive solar nebula and on chemical evolution of interstellar space in this part of the galaxy can be deduced from it. Isotope ratio in solar system got from laboratory study of extraterrestrial materials is a subject of this colloquium. Then isotope ratio measured in solar wind, planets and comets. Measurements either are made in-situ by mass spectrometry of ions in solar wind or planetery atmosphere gases either are remote measurements of spectra emitted by giant planets and comets. At last, planetology and astrophysics implications are presented and reviewed. Consraints for solar system formation model can be deduced from isotope ratio measurement. Particularly, isotope anomalies are marks of the processes, which have influenced the primitive solar nebula contraction

  5. Diurnal variations of carbonaceous components, major ions, and stable carbon and nitrogen isotope ratios in suburban aerosols from northern vicinity of Beijing

    Science.gov (United States)

    He, Nannan; Kawamura, Kimitaka; Kanaya, Yugo; Wang, Zifa

    2015-12-01

    We report diurnal variations of organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and major ions as well as stable carbon and nitrogen isotope ratios (δ13C and δ15N) in ambient aerosols at a suburban site (Mangshan), 40 km north of Beijing, China. We found that aerosol chemical compositions were largely controlled by the air mass transport from Beijing in daytime with southerly winds and by relatively fresh air mass in nighttime from the northern forest areas with northerly winds. Higher concentrations of aerosol mass and total carbon were obtained in daytime. Further, higher OC/EC ratios were recorded in daytime (4.0 ± 1.7) than nighttime (3.2 ± 0.7), suggesting that OC is formed by photochemical oxidation of gaseous precursors in daytime. Contributions of WSOC to OC were slightly higher in daytime (38%) than nighttime (34%), possibly due to secondary formation of WSOC in daytime. We also found higher concentrations of Ca2+ in daytime, which was originated from the construction dust in Beijing area and transported to the sampling site. δ13C ranged from -25.3 to -21.2‰ (ave. -23.5 ± 0.9‰) in daytime and -29.0 to -21.4‰ (-24.0 ± 1.5‰) in nighttime, suggesting that Mangshan aerosols were more influenced by fossil fuel combustion products in daytime and by terrestrial C3 plants in nighttime. This study suggests that daytime air mass delivery from megacity Beijing largely influence the air quality at the receptor site in the north together with photochemical processing of organic aerosols during the atmospheric transport, whereas the Mangshan site is covered with relatively clean air masses at night.

  6. Diurnal variations of carbonaceous components, major ions, and stable carbon and nitrogen isotope ratios in suburban aerosols from northern vicinity of Beijing

    Science.gov (United States)

    He, Nannan; Kawamura, Kimitaka; Kanaya, Yugo; Wang, Zifa

    2015-12-01

    We report diurnal variations of organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and major ions as well as stable carbon and nitrogen isotope ratios (δ13C and δ15N) in ambient aerosols at a suburban site (Mangshan), 40 km north of Beijing, China. We found that aerosol chemical compositions were largely controlled by the air mass transport from Beijing in daytime with southerly winds and by relatively fresh air mass in nighttime from the northern forest areas with northerly winds. Higher concentrations of aerosol mass and total carbon were obtained in daytime. Further, higher OC/EC ratios were recorded in daytime (4.0 ± 1.7) than nighttime (3.2 ± 0.7), suggesting that OC is formed by photochemical oxidation of gaseous precursors in daytime. Contributions of WSOC to OC were slightly higher in daytime (38%) than nighttime (34%), possibly due to secondary formation of WSOC in daytime. We also found higher concentrations of Ca2+ in daytime, which was originated from the construction dust in Beijing area and transported to the sampling site. δ13C ranged from -25.3 to -21.2‰ (ave. -23.5 ± 0.9‰) in daytime and -29.0 to -21.4‰ (-24.0 ± 1.5‰) in nighttime, suggesting that Mangshan aerosols were more influenced by fossil fuel combustion products in daytime and by terrestrial C3 plants in nighttime. This study suggests that daytime air mass delivery from megacity Beijing largely influence the air quality at the receptor site in the north together with photochemical processing of organic aerosols during the atmospheric transport, whereas the Mangshan site is covered with relatively clean air masses at night.

  7. Advances in optical water isotope ratio measurements

    International Nuclear Information System (INIS)

    Isotope ratio mass spectrometers routinely achieve impressive measurement precision and high throughput. In spite of this, a number of fundamental and practical problems are encountered. These are most notable in the case of water, arguably the most important molecule in the environment. Optical techniques to measure stable isotope ratios are able to address at least some of these issues; particularly, in relation to sample pretreatment and the difficulty of in-situ measurements. After discussing some general design criteria for infrared laser-based isotope ratio spectrometers, the case made above will be illustrated with a number of different instruments in applications from earthbound to the atmospheric: From laboratory based ice-core water isotope analyses to in-situ water isotope measurements in the upper troposphere and lower stratosphere. (author)

  8. Increase in soil stable carbon isotope ratio relates to loss of organic carbon: results from five long-term bare fallow experiments

    DEFF Research Database (Denmark)

    Menichetti, Lorenzo; Houot, Sabine; van Oort, Folkert;

    2015-01-01

    Changes in the 12C/13C ratio (expressed as δ13C) of soil organic C (SOC) has been observed over long time scales and with depth in soil profiles. The changes are ascribed to the different reaction kinetics of 12C and 13C isotopes and the different isotopic composition of various SOC pool components...... examined. The overall estimate of the fractionation coefficient (ε) was −1.2 ± 0.3 ‰. This coefficient represents an important input to studies of long-term SOC dynamics in agricultural soils that are based on variations in 13C natural abundance. The variance of ε may be ascribed to site characteristics....... However, experimental verification of the subtle isotopic shifts associated with SOC turnover under field conditions is scarce. We determined δ13C and SOC in soil sampled during 1929–2009 in the Ap-horizon of five European long-term bare fallow experiments kept without C inputs for 27–80 years and...

  9. Variations in carbon isotope ratios of C3 plants and distribution of C4 plants along an altitudinal transect on the eastern slope of Mount Gongga

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Variations in carbon isotopic ratios (δ 13C) of C3 plants and distribution of C4 plants were investigated along an altitudinal transect on the eastern slope of Mount Gongga, and the environmental effects on them were discussed. It is shown that plants with C4 photosynthetic pathway mainly occur at altitudes below 2100 m a.s.l., suggesting that the low summer temperature is responsible for the distributional pattern. In addition, δ 13C of C3 plants increases with elevation at the region above 2000 m a.s.l. with the characteristics of humid climate, and the increase rate in δ 13C for C3 plants is about 1.3‰ per kilometer. Temperature determines the altitudinal trend of δ 13C.

  10. Variations in carbon isotope ratios of C_3 plants and distribution of C_4 plants along an altitudinal transect on the eastern slope of Mount Gongga

    Institute of Scientific and Technical Information of China (English)

    LI JiaZhu; WANG GuoAn; LIU XianZhao; HAN JiaMao; LIU Min; LIU XiaoJuan

    2009-01-01

    Variations in carbon isotopic ratios (δ~(13)C) of C_3 plants and distribution of C_4 plants were investigated along an altitudinal transect on the eastern slope of Mount Gongga,and the environmental effects on them were discussed,it is shown that plants with C_4 photosynthetic pathway mainly occur at altitudes below 2100 m a.a.l.,suggesting that the low summer temperature is responsible for the distributional pattern.In addition,δ~(13)C of C_3 plants increases with elevation at the region above 2000 m a.s.l,with the characteristics of humid climate,and the increase rate in δ~(13)C for C_3 plants is about 1.3‰ per kilometer.Temperature determines the altitudinal trend of δ~(13)C.

  11. Temporal variations of the carbon isotopic ratio of atmospheric methane observed at Ny Ålesund, Svalbard from 1996 to 2004

    Science.gov (United States)

    Morimoto, Shinji; Aoki, Shuji; Nakazawa, Takakiyo; Yamanouchi, Takashi

    2006-01-01

    Systematic observations of the atmospheric CH4 mole fraction and its carbon isotope ratio δ13CH4 have been carried out at Ny Ålesund, Svalbard (78°55'N, 11°56'E) since 1991 and 1996, respectively. The CH4 and δ13CH4 showed clear seasonal cycles with respective peak-to-peak amplitudes of 48 ppb and 0.42‰. By comparing the anomalies in the increase rate of the CH4 with those of δ13CH4, it is suggested that the cause of the rapid increase in the CH4 mole fraction observed at Ny Ålesund in 1998 could be attributable to an enhanced CH4 release from wetland and biomass burning.

  12. Hydrogen and carbon abundances and isotopic ratios in apatite from alkaline intrusive complexes, with a focus on carbonatites

    Energy Technology Data Exchange (ETDEWEB)

    Nadeau, S.L.; Epstein, S.; Stolper, E. [California Inst. of Tech., Pasadena, CA (United States). Div. of Geological and Planetary Sciences

    1999-06-01

    The authors report H and C contents and {delta}D and {delta}{sup 13}C values of apatites from 15 alkaline intrusive complexes ranging in age from 110 Ma to 2.6 Ga. Sampling focused on carbonatites, but included silicate rocks as well. Heating temperatures up to 1,500 C is needed to extract fully H{sub 2}O and CO{sub 2} from these apatites. Apatites from carbonatite-rich intrusive complexes contain 0.2--1.1 wt% H{sub 2}O and 0.05--0.70 wt% CO{sub 2}; apatites from two silicate-rich alkaline complexes with little or no carbonatite are generally poorer in both volatile components (0.1--0.2% H{sub 2}O and 0.01--0.11% CO{sub 2}). D/H ratios in apatites from these rocks are bimodally distributed. The authors suggest that the {delta}D values of group I apatites represent primitive, mantle-derived values and that the group II apatites crystallized from degassed magmas, resulting in lower H{sub 2}O contents and {delta}D values. In contrast to H{sub 2}O contents and {delta}D values, CO{sub 2} contents and {delta}{sup 13}C values of gas released at high temperatures from multiple aliquots of these apatite samples are variable. This suggests the presence of more than one C-bearing component in these apatites, one of which is proposed to be dissolved carbonate; the other could be associated with hydrocarbons.

  13. Biology and air–sea gas exchange controls on the distribution of carbon isotope ratios13C) in the ocean

    OpenAIRE

    A. Schmittner; Gruber, N.; Mix, A. C.; Key, R.M.; Tagliabue, A.; Westberry, T. K.

    2013-01-01

    Analysis of observations and sensitivity experiments with a new three-dimensional global model of stable carbon isotope cycling elucidate processes that control the distribution of δ13C of dissolved inorganic carbon (DIC) in the contemporary and preindustrial ocean. Biological fractionation and the sinking of isotopically light δ13C organic matter from the surface into the interior ocean leads to low δ13CDIC values at depths and in high latitude surface waters and high...

  14. Biology and air–sea gas exchange controls on the distribution of carbon isotope ratios (δ13C) in the ocean

    OpenAIRE

    A. Schmittner; Gruber, N.; Mix, A. C.; Key, R.M.; Tagliabue, A.; Westberry, T. K.

    2013-01-01

    Analysis of observations and sensitivity experiments with a new three-dimensional global model of stable carbon isotope cycling elucidate the processes that control the distribution of δ13C in the contemporary and preindustrial ocean. Biological fractionation dominates the distribution of δ13CDIC of dissolved inorganic carbon (DIC) due to the sinking of isotopically light δ13C organic matter from the surface into the interior ocean. This process leads to low δ13CDI...

  15. Carbon isotopes in photosynthesis

    International Nuclear Information System (INIS)

    The efficiency of photosynthesis continues to interest biochemists, biologists, and plant physiologists. Scientists interested in CO2 uptake are concerned about the extent to which the uptake rate is limited by such factors as stomatal diffusion and the chemistry of the CO2 absorption process. The fractionation of carbon isotopes that occurs during photosynthesis is one of the most useful techniques for investigating the efficiency of CO2 uptake

  16. Pan-Arctic concentrations of mercury and stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) in marine zooplankton.

    Science.gov (United States)

    Pomerleau, Corinne; Stern, Gary A; Pućko, Monika; Foster, Karen L; Macdonald, Robie W; Fortier, Louis

    2016-05-01

    Zooplankton play a central role in marine food webs, dictating the quantity and quality of energy available to upper trophic levels. They act as "keystone" species in transfer of mercury (Hg) up through the marine food chain. Here, we present the first Pan-Arctic overview of total and monomethylmercury concentrations (THg and MMHg) and stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) in selected zooplankton species by assembling data collected between 1998 and 2012 from six arctic regions (Laptev Sea, Chukchi Sea, southeastern Beaufort Sea, Canadian Arctic Archipelago, Hudson Bay and northern Baffin Bay). MMHg concentrations in Calanus spp., Themisto spp. and Paraeuchaeta spp. were found to increase with higher δ(15)N and lower δ(13)C. The southern Beaufort Sea exhibited both the highest THg and MMHg concentrations. Biomagnification of MMHg between Calanus spp. and two of its known predators, Themisto spp. and Paraeuchaeta spp., was greatest in the southern Beaufort Sea. Our results show large geographical variations in Hg concentrations and isotopic signatures for individual species related to regional ecosystem features, such as varying water masses and freshwater inputs, and highlight the increased exposure to Hg in the marine food chain of the southern Beaufort Sea. PMID:26874765

  17. Coastal climate reflected in carbon-13/carbon-12 ratio of organic carbon in varved sediment from Santa Barbara basin

    OpenAIRE

    Schimmelmann, Arndt; Tegner, Mia J.

    1991-01-01

    A 1844-1987 time-series of carbon stable isotope ratios from dated sedimentary total organic carbon from the center of the Santa Barbara basin is compared with historical climate and oceanographic records. Carbon derived from carbon-13-depleted phytoplankton and carbon-13-enriched kelp appear responsible for a large part of the isotopic variance in sedimentary total organic carbon. El Niño/Southern Oscillation events are recorded by the isotopic response of marine organic carbon in sediments.

  18. Isotope ratio in stellar atmospheres and nucleosynthesis

    International Nuclear Information System (INIS)

    The determination of isotopic ratios in stellar atmospheres is studied. The isotopic shift of atomic and molecular lines of different species of a certain element is examined. CH and MgH lines are observed in order to obtain the 12C: 13C and 24Mg: 25Mg: 26Mg isotpic ratios. The formation of lines in stellar atmospheres is computed and the resulting synthetic spectra are employed to determine the isotopic abundances. The results obtained for the isotopic ratios are compared to predictions of nucleosynthesis theories. Finally, the concept of primary and secondary element is discussed, and these definitions are applied to the observed variations in the abundance of elements as a function of metallicity. (author)

  19. Carbon and oxygen isotope microanalysis of carbonate.

    Science.gov (United States)

    Velivetskaya, Tatiana A; Ignatiev, Alexander V; Gorbarenko, Sergey A

    2009-08-30

    Technical modification of the conventional method for the delta(13)C and delta(18)O analysis of 10-30 microg carbonate samples is described. The CO(2) extraction is carried out in vacuum using 105% phosphoric acid at 95 degrees C, and the isotopic composition of CO(2) is measured in a helium flow by gas chromatography/isotope ratio mass spectrometry (GC/IRMS). The feed-motion of samples to the reaction vessel provides sequential dropping of only the samples (without the sample holder) into the acid, preventing the contamination of acid and allowing us to use the same acid to carry out very large numbers of analyses. The high accuracy and high reproducibility of the delta(13)C and delta(18)O analyses were demonstrated by measurements of international standards and comparison of results obtained by our method and by the conventional method. Our method allows us to analyze 10 microg of the carbonate with a standard deviation of +/-0.05 per thousand for delta(13)C and delta(18)O. The method has been used successfully for the analyses of the oxygen and carbon isotopic composition of the planktonic and benthic foraminifera in detailed palaeotemperature reconstructions of the Okhotsk Sea. PMID:19603476

  20. On carbon and oxygen isotope ratios in starburst galaxies: New data from NGC253 and Mrk231 and their implications

    CERN Document Server

    Henkel, C; Ao, Y; Aalto, S; Danielson, A L R; Papadopoulos, P P; Garcia-Burillo, S; Aladro, R; Impellizzeri, C M V; Mauersberger, R; Martin, S; Harada, N

    2014-01-01

    Using the IRAM 30-m telescope, CN and CO isotopologues have been measured toward the central regions of the nearby starburst galaxy NGC253 and the prototypical ultraluminous infrared galaxy Mrk231. In NGC253, the 12C/13C ratio is 40+-10. Assuming that the ratio also holds for the CO emitting gas, this yields 16O/18O = 145+-36 and 16O/17O = 1290+-365 and a 32S/34S ratio close to that measured for the local interstellar medium (20-25). No indication for vibrationally excited CN is found. Peak line intensity ratios between NGC253 and Mrk231 are ~100 for 12C16O and 12C18O J=1-0, while the ratio for 13C16O J=1-0 is ~250. This and similar 13CO and C18O line intensities in the J=1-0 and 2-1 transitions of Mrk231 suggest 12C/13C ~ 100 and 16O/18O ~ 100, in agreement with values obtained for the less evolved ultraluminous merger Arp220. Also accounting for other extragalactic data, 12C/13C ratios appear to vary over a full order of magnitude, from >100 in ultraluminous high redshift galaxies to ~100 in more local such...

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

    Science.gov (United States)

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

    2016-04-01

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

  2. Stable carbon isotope analysis of heavy oils

    Energy Technology Data Exchange (ETDEWEB)

    Fixari, B.; Le Perchec, P.; Bigois, M.; Casabianca, H.; Jame, P. [CNRS, Vernaison (France). Lab. des Materiaux Organiques

    1994-03-01

    Stable carbon isotope analysis of various heavy oils and some thermo-catalytically converted products was performed with a thermal analyser coupled with an isotopic ratio mass spectrometer. The temperature-programmed oxidative pyroanalysis technique subdivides the classical {sup 13}C/{sup 12}C ratio, affording new insights into the structural composition of heavy oils such as the contribution of naphthenoaromatics, and appears to be of interest for following their thermal refining. 24 refs., 11 figs., 2 tabs.

  3. High-precision mass spectrometric hydrogen isotope ratio measurements

    International Nuclear Information System (INIS)

    The analytical capabilities of mass spectrometric ion-current measurement systems are described on both a theoretical and a practical basis. From the theoretical standpoint, a signal-to-noise ratio (S/N) model that evaluated the fundamental sources of noise present in ion-current measurement systems was developed. Use of this model accurately predicted the performance (precision) for ion-current ratio measurements made by two isotope ratio mass spectrometers, one designed for carbon isotopic measurements, and the other designed for hydrogen isotopic measurements. Isotope ratio measurements differ from current-ratio measurements in that the observed ion-current ratio must be corrected to reflect the ratio of the ion currents due to the isotopic species of interest, which, for hydrogen isotope ratio mass spectrometry, are HD+ and H2+. Interfaces to these two ion currents are described in detail. To compensate for H3+ three measurement procedures, the two-standard calibration, the one-standard differential measurement with electronic H3+ compensation, and the two-standard differential measurement, are described. The one- and two-standard differential measurements were successfully used for measurement of isotopic abundances. Results of a collaborative investigation to validate the use of 18O in place of D as an isotopic label for total body water measurements are presented. In this research both 18O and D were administered simultaneously to several subjects. The weight of total body water of these subjects as measured by the dilution of D into the body water was in good agreement with the results of the 18O measurements. A brief description of the laboratory computer system is also given

  4. Effects of sample preparation on stable isotope ratios of carbon and nitrogen in marine invertebrates: implications for food web studies using stable isotopes.

    Science.gov (United States)

    Mateo, Miguel A; Serrano, Oscar; Serrano, Laura; Michener, Robert H

    2008-08-01

    Trophic ecology has benefitted from the use of stable isotopes for the last three decades. However, during the last 10 years, there has been a growing awareness of the isotopic biases associated with some pre-analytical procedures that can seriously hamper the interpretation of food webs. We have assessed the extent of such biases by: (1) reviewing the literature on the topic, and (2) compiling C and N isotopic values of marine invertebrates reported in the literature with the associated sample preparation protocols. The factors considered were: acid-washing, distilled water rinsing (DWR), sample type (whole individuals or pieces of soft tissues), lipid content, and gut contents. Two-level ANOVA revealed overall large and highly significant effects of acidification for both delta(13)C values (up to 0.9 per thousand decrease) and delta(15) N values (up to 2.1 per thousand decrease in whole individual samples, and up to 1.1 per thousand increase in tissue samples). DWR showed a weak overall effect with delta(13)C increments of 0.6 per thousand (for the entire data set) or decrements of 0.7 per thousand in delta(15) N values (for tissue samples). Gut contents showed no overall significant effect, whereas lipid extraction resulted in the greatest biases in both isotopic signatures (delta(13)C, up to -2.0 per thousand in whole individuals; delta(15)N, up to +4.3 per thousand in tissue samples). The study analyzed separately the effects of the various factors in different taxonomic groups and revealed a very high diversity in the extent and direction of the effects. Maxillopoda, Gastropoda, and Polychaeta were the classes that showed the largest isotopic shifts associated with sample preparation. Guidelines for the standardization of sample preparation protocols for isotopic analysis are proposed both for large and small marine invertebrates. Broadly, these guidelines recommend: (1) avoiding both acid washing and DWR, and (2) performing lipid extraction and gut

  5. A high-precision measurement system for carbon and hydrogen isotopic ratios of atmospheric methane and its application to air samples collected in the western pacific region

    International Nuclear Information System (INIS)

    In order to study temporal and spatial variations of atmospheric CH4 quantitatively, we originally improved a measurement system for carbon and hydrogen isotopic ratios (δ13C and δD) of CH4 to attain high-precision measurements. By analyzing 100 mL aliquots of an ambient air sample, the precision of our system is 0.08 per mille for δ13C and 2.2 per mille for δD (1σ), which are one of the highest precisions reported so far. The system consists mainly of a CH4 preconcentration device and a continuous-flow gas chromatograph isotope ratio mass spectrometer equipped with a combustion furnace and a pyrolysis furnace for measurements of δ13C and δD. The preconcentration trap temperature was maintained at -130 ±1degC during collection of CH4 from the air sample by passing it through the trap, then at -83 ± 1degC while remaining air components such as N2 and O2 except for CH4 escaped, and finally at 100±1degC for CH4 elusion. The isotopic values are measured on a mass spectrometer, relative to respective reference gases. For this study, the δ13C and δD values of the reference gases were calibrated against our primary standards provided by the IAEA: our δ13C primary standards is NBS18, whereas our δD primary standards are V-SMOW and SLAP. To ensure the long-term stability and reproducibility of our measurement system, a calibrated whole air stored in a high-pressure cylinder, which was called 'test gas', was measured at least twice on each day when sample measurements were made. To measure small air samples, such as those extracted from ice cores, we also examined the relation between the sample size and the measured value of δ13C and δD: gradual enrichment of the δ13C occurred with decreasing CH4 content less than 8 nmol whereas no such effect could be seen for the δD. Furthermore, preliminary results of latitudinal distributions of δ13C and δD were discussed along with CH4 concentrations obtained by our shipboard air-sampling program. (author)

  6. Pacific sleeper shark Somniosus pacificus trophic ecology in the eastern North Pacific Ocean inferred from nitrogen and carbon stable-isotope ratios and diet.

    Science.gov (United States)

    Courtney, D L; Foy, R

    2012-04-01

    Stable-isotope ratios of nitrogen (δ¹⁵N) and lipid-normalized carbon (δ¹³C') were used to examine geographic and ontogenetic variability in the trophic ecology of a high latitude benthopelagic elasmobranch, the Pacific sleeper shark Somniosus pacificus. Mean muscle tissue δ¹³C' values of S. pacificus differed significantly among geographic regions of the eastern North Pacific Ocean. Linear models identified significant ontogenetic and geographic variability in muscle tissue δ¹⁵N values of S. pacificus. The trophic position of S. pacificus in the eastern North Pacific Ocean estimated here from previously published stomach-content data (4·3) was within the range of S. pacificus trophic position predicted from a linear model of S. pacificus muscle tissue δ¹⁵N (3·3-5·7) for fish of the same mean total length (L(T) ; 201·5 cm), but uncertainty in predicted trophic position was very high (95% prediction intervals ranged from 2·9 to 6·4). The relative trophic position of S. pacificus determined here from a literature review of δ¹⁵N by taxa in the eastern North Pacific Ocean was also lower than would be expected based on stomach-content data alone when compared to fishes, squid and filter feeding whales. Stable-isotope analysis revealed wider variability in the feeding ecology of S. pacificus in the eastern North Pacific Ocean than shown by diet data alone, and expanded previous conclusions drawn from analyses of stomach-content data to regional and temporal scales meaningful for fisheries management. PMID:22497395

  7. Carbon isotope ratios document that the elytra of western corn rootworm (Coleoptera: Chrysomelidae) reflects adult versus larval feeding and later instar larvae prefer Bt corn to alternate hosts.

    Science.gov (United States)

    Hiltpold, Ivan; Adamczyk, John J; Higdon, Matthew L; Clark, Thomas L; Ellersieck, Mark R; Hibbard, Bruce E

    2014-06-01

    In much of the Corn Belt and parts of Europe, the western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most important insect pest of maize. The need for additional basic knowledge of this pest has been highlighted while developing resistance management plans for insecticidal genetically modified crops. This study evaluated the possibility of tracking feeding habits of western corn rootworm larvae using stable carbon isotope signatures. Plants accumulate different ratios of (13)C:(12)C isotopes, usually expressed as δ(13)C, according to whether they use the C3 or C4 photosynthetic pathway. Herbivore biomass is expected to reflect the δ(13)C of the food they eat. For the current experiment, western corn rootworm larvae were grown on different species of plants exhibiting different δ(13)C values. The δ(13)C values were then measured in elytra of emerged beetles. When beetles were unfed, biomass reflected larval feeding. When beetles were fed for 31 d postemergence, δ(13)C values of elytra almost exclusively reflected adult feeding. These results suggest the use of caution in the interpretation of δ(13)C data aiming to document larval diet history when adult feeding history is unknown. The technique was also used to evaluate western corn rootworm larval choice between alternate hosts and maize with and without genetically modified (Bt) traits aimed at their control. Propensity for feeding on alternate hosts versus maize was biased toward feeding on maize regardless whether the maize had Bt or not, suggesting western corn rootworm larvae were not repelled by Bt. These data will be helpful for regulators in interpreting western corn rootworm feeding data on Bt maize. PMID:24874160

  8. Carbon isotope geochemistry in the Yalujiang estuary

    Institute of Scientific and Technical Information of China (English)

    吴莹; 张经

    2001-01-01

    The distribution of particulate organic carbon (POC) along the lower reaches is similar between the dry season and the flood season in the Yalujiang Estuary, North China. However, the values of particulate organic carbon of the upperstream in the dry season are one magnitude lower than the concentrations in the flood season. Stable carbon isotope ratios have been used to study the sources of particulate organic carbon in the Yalujiang Estuary. The isotopic composition of POC shows a range from -23.1‰ to -29.4‰ with a little seasonal variation. The isotopic evidence indicates that the POC in the Yalujiang Estuary is predominantly of terrestrial origin rather than a result of in situ plankton. The study of the ratio of POC: Chla shows that the turbidity maximum plays an important role in POC cycle in the Yalujiang Estuary. Organic detritus and soil erosion are the main contributions to POC in the turbidity maximum, especially in the flood season.

  9. Temporal changes in carbon and nitrogen stable isotope ratios of macrozoobenthos on an artificial tidal flat facing a hypertrophic canal, inner Tokyo Bay

    International Nuclear Information System (INIS)

    Highlights: • Temporal changes in food web structure were analyzed in a tidal flat in a hypertrophic coastal bay. • Microphytobenthos mainly supported the benthic food web throughout seasons. • Phytoplankton and terrestrial detritus were utilized after red tides and urban runoffs. • Seasonal changes in consumer-δ15N was much larger in inner Tokyo Bay than in other estuaries. • This study showed specific characteristics of benthic food web in highly urbanized estuaries. -- Abstract: Temporal changes in benthic food web structure were analyzed in an artificial tidal flat in inner Tokyo Bay, Japan, using carbon and nitrogen stable isotope ratios (δ13C and δ15N). Microphytobenthos were the most important food sources of macrozoobenthos, due to high microphytobenthic biomass on the tidal flat, while phytoplankton in canal water (canal POMPP), terrestrial materials from urban surface runoff (canal POMTM), and marsh plants were less important. Dietary contribution of microphytobenthos was highest in April to June, while decreased towards December owing to the supply of canal POMPP and canal POMTM following red tides and heavy rainfall events in summer to fall. Temporal changes in δ15N (Δδ15N) of consumer corresponded well to the 15N-enrichment in canal POMPP in summer. A meta-analysis showed that the consumer-Δδ15N was considerably larger in inner Tokyo Bay than those in other estuaries, which may be a specific characteristic of benthic food web in highly urbanized estuaries

  10. Sulphur isotope ratios in Philippine geothermal systems

    International Nuclear Information System (INIS)

    This paper presents data on sulfur isotope ratios in dissolved sulfate, H2S gas, anhydrite and pyrite minerals in four Philippine geothermal fields - Palinpinon, Mahanagdong, Mt. Apo and Bacon-Manito. Isotope ratios are used to determine the source of sulfur species in each geothermal system. Fluid temperature estimates using sulfur pairs are also included in the discussion. Finally, oxygen isotope distribution in dissolved sulfate, anhydrite and water is introduced. Dissolved sulfate sulfur isotope ratios can be divided into three groups: heavy (δ34S>15 per mille CDT), light (∼ 0 per mille) and transitional or mixed ratios (1-15 per mille). The heavy samples represent waters that have attained some degree of isotopic equilibrium with co-existing sulfides, either in the present geothermal environments or at deeper, hotter levels of the hydrothermal systems. Most of the well fluids in Palinpinon, Mahanagdong and Bacon-Manito belong to this group. Light fluids, on the other hand, are typical of surface and shallow thermal features, where H2S gas is oxidized and converted to SO4. The δ34SSO4 ratios here mirror that of the source H2S. Slightly heavy ratios, characteristic of Mt. Apo well waters, are apparently produced by dilution of 'heavy' fluids with 'light' waters, in this specific case the light end-member being steam condensate. δ34SH2S of well samples in Palinpinon, Mahanagdong and Bacon-Manito are in the vicinity of 0 per mille, similar to that of magmatic H2S and H2S produced from SO2 disproportionation. This implies that geothermal H2S in these fields are derived either directly or indirectly from a magmatic source. In Mt. Apo, δ34SH2S are depleted at -3 to -4 per mille. Although the ultimate source is still magmatic in origin, the depleted ratios are thought to be effects of extensive degassing of an originally δ34S-enriched reservoir fluid. Sulfur ratios in anhydrite are similar to those of dissolved SO4, suggesting that dissolved sulfate is the

  11. Feasibility of Isotopic Measurements: Graphite Isotopic Ratio Method

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Thomas W.; Gerlach, David C.; Reid, Bruce D.; Morgan, W. C.

    2001-04-30

    This report addresses the feasibility of the laboratory measurements of isotopic ratios for selected trace constituents in irradiated nuclear-grade graphite, based on the results of a proof-of-principal experiment completed at Pacific Northwest National Laboratory (PNNL) in 1994. The estimation of graphite fluence through measurement of isotopic ratio changes in the impurity elements in the nuclear-grade graphite is referred to as the Graphite Isotope Ratio Method (GIRM). Combined with reactor core and fuel information, GIRM measurements can be employed to estimate cumulative materials production in graphite moderated reactors. This report documents the laboratory procedures and results from the initial measurements of irradiated graphite samples. The irradiated graphite samples were obtained from the C Reactor (one of several production reactors at Hanford) and from the French G-2 Reactor located at Marcoule. Analysis of the irradiated graphite samples indicated that replicable measurements of isotope ratios could be obtained from the fluence sensitive elements of Ti, Ca, Sr, and Ba. While these impurity elements are present in the nuclear-grade graphite in very low concentrations, measurement precision was typically on the order of a few tenths of a percent to just over 1 percent. Replicability of the measurements was also very good with measured values differing by less than 0.5 percent. The overall results of this initial proof-of-principal experiment are sufficiently encouraging that a demonstration of GIRM on a reactor scale basis is planned for FY-95.

  12. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past....... Processes that potentially fractionate Cr isotopes, perhaps during deposition, burial and alteration need to be constrained.Previous studies have shown that Cr isotopes are fractionated during oxidative weathering on land, where heavy Cr isotopes are preferentially removed with Cr(VI) while residual soils...... retain an isotopically light Cr signature. Cr(VI) enriched in heavy Cr isotopes is then transported via river waters to the oceans and sequestered into marine sediments. Marine chemical sediments such asbanded iron formations and modern marine carbonates have proven useful in recording the Cr isotope...

  13. Zinc isotope ratios as indicators of diet and trophic level in Arctic marine mammals

    OpenAIRE

    Klervia Jaouen; Paul Szpak; Richards, Michael P.

    2016-01-01

    Carbon and nitrogen stable isotope ratios of bone collagen are an established method for dietary reconstruction, but this method is limited by the protein preservation. Zinc (Zn) is found in bioapatite and the isotopic compositions of this element constitute a very promising dietary indicator. The extent of fractionation of Zn isotopes in marine environments, however, remains unknown. We report here on the measurement of zinc, carbon and nitrogen isotopes in 47 marine mammals from the archaeo...

  14. Stable Carbon Isotope Ratios of Individual Pollen Grains as a Proxy for C3- Versus C4-Grass Abundance in Paleorecords: A Validation Study

    Science.gov (United States)

    Nelson, D. M.; Hu, F.; Pearson, A.

    2007-12-01

    C3 and C4 grasses have distinct influences on major biogeochemical processes and unique responses to important environmental controls. Difficulties in distinguishing between these two functional groups of grasses have hindered paleoecological studies of grass-dominated ecosystems. We recently developed a technique to analyze the stable carbon isotope composition of individual grass-pollen grains using a spooling- wire microcombustion device interfaced with an isotope-ratio mass spectrometer (Nelson et al. 2007). This technique holds promise for improving C3 and C4 grass reconstructions. It requires ~90% fewer grains than typical methods and avoids assumptions associated with mixing models. However, our previous work was based on known C3 and C4 grasses from herbarium specimens and field collections and the technique had not been test using geological samples. To test the ability of this technique to reproduce the abundance of C3 and C4 grasses on the landscape, we measured δ13C values of >1500 individual grains of grass pollen isolated from the surface sediments of 10 North American lakes that span a large gradient of C3 and C4 grass abundance. Results indicate a strong positive correlation (r=0.94) between % C4-grass pollen (derived from classifying δ13C values from single grains as C3 and C4) and the literature-reported abundance of C4 grasses on the landscape. However, the measured % C4-grass pollen shows some deviation from the actual abundance at sites with high proportions of C4 grasses. This is likely caused by uncertainty in the magnitude, composition, and variability of the analytical blank associated with these measurements. Correcting for this deviation using regression analysis improves the estimation of the abundance of C4 grasses on the landscape. Comparison of the % C4-grass pollen with C/N and δ13C measurements of total organic matter in the same lake-sediment samples illustrates the distinct advantage of grass-pollen δ13C as a proxy for

  15. Evaluation of bioremediation systems utilizing stable carbon isotope analysis

    International Nuclear Information System (INIS)

    Carbon, whether in an organic or inorganic form, is composed primarily of two stable isotopes, carbon-12 and carbon-13. The ratio of carbon-12 to carbon-13 is approximately 99:1. The stable carbon isotope ratios of most natural carbon materials of biological interest range from approximately 0 to -110 per mil (per-thousand) versus the PDB standard. Utilizing stable carbon isotope analysis, it is often possible to determine the source(s) of the liberated carbon dioxide, thereby confirming successful mineralization of the targeted carbon compound(s) and, if the carbon dioxide results from multiple carbon compounds, in what ratio the carbon compounds are mineralized. Basic stable isotope 'theory' recommended sampling procedures and analysis protocols are reviewed. A case study involving fuel oil presented on the application of stable carbon isotope analysis for the monitoring and evaluation of in situ bioremediation. At the site, where a field bioventing study was being conducted, multiple potential sources of carbon dioxide production existed. Additional potential applications of stable carbon isotope analysis for bioremediation evaluation and monitoring are discussed

  16. Organic chemistry of Murchison meteorite: Carbon isotopic fractionation

    Science.gov (United States)

    Yuen, G. U.; Blair, N. E.; Desmarais, D. J.; Cronin, J. R.; Chang, S.

    1986-01-01

    The carbon isotopic composition of individual organic compounds of meteoritic origin remains unknown, as most reported carbon isotopic ratios are for bulk carbon or solvent extractable fractions. The researchers managed to determine the carbon isotopic ratios for individual hydrocarbons and monocarboxylic acids isolated from a Murchison sample by a freeze-thaw-ultrasonication technique. The abundances of monocarboxylic acids and saturated hydrocarbons decreased with increasing carbon number and the acids are more abundant than the hydrocarbon with the same carbon number. For both classes of compounds, the C-13 to C-12 ratios decreased with increasing carbon number in a roughly parallel manner, and each carboxylic acid exhibits a higher isotopic number than the hydrocarbon containing the same number of carbon atoms. These trends are consistent with a kinetically controlled synthesis of higher homologues for lower ones.

  17. Applications of cavity ring-down spectroscopy to high precision isotope ratio measurement of 13C/12C in carbon dioxide.

    Science.gov (United States)

    Wahl, Ed H; Fidric, Bernard; Rella, Chris W; Koulikov, Sergei; Kharlamov, Boris; Tan, Sze; Kachanov, Alexander A; Richman, Bruce A; Crosson, Eric R; Paldus, Barbara A; Kalaskar, Shashi; Bowling, David R

    2006-03-01

    Recent measurements of carbon isotopes in carbon dioxide using near-infrared, diode-laser-based cavity ring-down spectroscopy (CRDS) are presented. The CRDS system achieved good precision, often better than 0.2 per thousand, for 4% CO2 concentrations, and also achieved 0.15-0.25 per thousand precision in a 78 min measurement time with cryotrap-based pre-concentration of ambient CO2 concentrations (360 ppmv). These results were obtained with a CRDS system possessing a data rate of 40 ring-downs per second and a loss measurement of 4.0 x 10(-11) cm(-1) Hz(-1/2). Subsequently, the measurement time has been reduced to under 10 min. This standard of performance would enable a variety of high concentration (3-10%) isotopic measurements, such as medical human breath analysis or animal breath experiments. The extension of this ring-down to the 2 microm region would enable isotopic analysis at ambient concentrations, which, combined with the small size, robust design, and potential for frequent measurements at a remote site, make CRDS technology attractive for remote atmospheric measurement applications. PMID:16500752

  18. (Carbon isotope fractionation inplants)

    Energy Technology Data Exchange (ETDEWEB)

    O' Leary, M.H.

    1990-01-01

    The objectives of this research are: To develop a theoretical and experimental framework for understanding isotope fractionations in plants; and to develop methods for using this isotope fractionation for understanding the dynamics of CO{sub 2} fixation in plants. Progress is described.

  19. Stable isotope ratios in hair and teeth reflect biologic rhythms.

    Directory of Open Access Journals (Sweden)

    Otto Appenzeller

    Full Text Available Biologic rhythms give insight into normal physiology and disease. They can be used as biomarkers for neuronal degenerations. We present a diverse data set to show that hair and teeth contain an extended record of biologic rhythms, and that analysis of these tissues could yield signals of neurodegenerations. We examined hair from mummified humans from South America, extinct mammals and modern animals and people, both healthy and diseased, and teeth of hominins. We also monitored heart-rate variability, a measure of a biologic rhythm, in some living subjects and analyzed it using power spectra. The samples were examined to determine variations in stable isotope ratios along the length of the hair and across growth-lines of the enamel in teeth. We found recurring circa-annual periods of slow and fast rhythms in hydrogen isotope ratios in hair and carbon and oxygen isotope ratios in teeth. The power spectra contained slow and fast frequency power, matching, in terms of normalized frequency, the spectra of heart rate variability found in our living subjects. Analysis of the power spectra of hydrogen isotope ratios in hair from a patient with neurodegeneration revealed the same spectral features seen in the patient's heart-rate variability. Our study shows that spectral analysis of stable isotope ratios in readily available tissues such as hair could become a powerful diagnostic tool when effective treatments and neuroprotective drugs for neurodegenerative diseases become available. It also suggests that similar analyses of archaeological specimens could give insight into the physiology of ancient people and animals.

  20. Depth Profiles of Stable Nitrogen and Carbon Isotopes and C:N Ratios in Surficial Sediments From the NW Insular Slope of Cuba.

    Science.gov (United States)

    Soto, L. A.; de La Lanza, G.; López-Veneroni, D.

    2007-05-01

    The deep sea floor in the studied area remained unexplored for several decades. Recent searching for fossil fuels and gas hydrates in the seabed has renewed interest in studying deep sea processes in the region. Near- surface sediments were recovered with a Reineick box-corer at 3 preselected quadrants located at the channel axis of the Florida Straits and the slope rise off NW Cuba at depths ranging from 1468 to 2094 m. A total of 12- 30 cm long- subcores were sampled for isotopic (15N/14N and 13C/12C) and C:N ratio analyses. Surficial sediment samples exhibited mostly enriched δ15N values ranging from +3.6 to +6.4‰ with an average of +5.4 ± 0.7. δ15N values in the deeper quadrants (I and II) near the channel axis were fairly homogeneous in contrast to the shallower one (III) located at the slope rise, which showed a higher variability and significantly depleted values (+3.6‰). Testing of equality of δ15N values among quadrants was rejected (Friedman's test p<0.368. From the estimated δ15N average value here recorded a significant input of organic matter from a pelagic source is inferred. The δ13C values had a narrow range in all quadrants (-18.5 to -19.13‰) with an average of - 18.71±0.17. A gradient slightly enriched is noted on the seabed from the westernmost quadrants(I and II)towards the slope rise (quadrant III). The average δ13C signal in surficial sediments from the Southern Straits approaches that known for the continental shelf of South Florida (-18.5±0.7). Vertical profiles of TOC and TN are highly heterogeneous among quadrants displaying a diminishing trend with depth (0- 18 cm). TOC values are mostly impoverished ranging from 0.16 to 0.67 mmol/g. Slope rise sites concentrated less TOC than locations near the channel axis. The opposite occurred with TN values. Sites near the slope rise attained 0.90 mmol/g whereas in the channel axis, nitrogen was reduced to 0.46mmol/g. C:N ratios ranged from 1.9 to 10.2. An increasing gradient was noted

  1. Carbon isotopes in biological carbonates: Respiration and photosynthesis

    Science.gov (United States)

    McConnaughey, T.A.; Burdett, J.; Whelan, J.F.; Paull, C.K.

    1997-01-01

    Respired carbon dioxide is an important constituent in the carbonates of most air breathing animals but is much less important in the carbonates of most aquatic animals. This difference is illustrated using carbon isotope data from freshwater and terrestrial snails, ahermatypic corals, and chemoautotrophic and methanotrophic pelecypods. Literature data from fish otoliths and bird and mammal shell and bone carbonates are also considered. Environmental CO2/O2 ratios appear to be the major controlling variable. Atmospheric CO2/O2 ratios are about thirty times lower than in most natural waters, hence air breathing animals absorb less environmental CO2 in the course of obtaining O2. Tissue CO2 therefore, does not isotopically equilibrate with environmental CO2 as thoroughly in air breathers as in aquatic animals, and this is reflected in skeletal carbonates. Animals having efficient oxygen transport systems, such as vertebrates, also accumulate more respired CO2 in their tissues. Photosynthetic corals calcify mainly during the daytime when photosynthetic CO2 uptake is several times faster than respiratory CO2 release. Photosynthesis, therefore, affects skeletal ??13C more strongly than does respiration. Corals also illustrate how "metabolic" effects on skeletal isotopic composition can be estimated, despite the presence of much larger "kinetic" isotope effects. Copyright ?? 1997 Elsevier Science Ltd.

  2. Stable carbon isotope ratios as indicators of marine versus terrestrial inputs to the diets of wild and captive tuatara (Sphenodon punctatus)

    International Nuclear Information System (INIS)

    Stable carbon isotope analysis was used to examine feeding relationships of wild tuatara on Stephens Island and captive tuatara in New Zealand institutions. We first measured delta 13C in three food items of wild tuatara. Pectoral muscle of fairy prions (a seabird eaten seasonally by tuatara) was significantly enriched in 13C compared with whole bodies of wild insects (darkling beetles and tree weta). Values for delta 13C in blood cells varied significantly among wild tuatara of different life-history stages. Male tuatara were more enriched in 13C than were females or juveniles, suggesting that males prey more heavily on seabirds. Insect foods of captive tuatara varied dramatically in delta/sup 13/C; this is attributed to differential consumption of plant material derived from the C3 and C4 photosynthetic pathways. Blood cells from four different groups of captive tuatara differed significantly in delta 13C. This was perhaps related to assimilation of insects with different delta 13C values, and cannot be attributed to differences in seabird predation as captive tuatara do not have access to seabirds. For wild tuatara on Stephens Island, stable carbon isotope analysis provides support for the dietary information available from behavioural observations, gut analyses and measurements of plasma composition. (author). 47 refs., 1 tab., 2 figs

  3. Anthropogenic impacts on mercury concentrations and nitrogen and carbon isotope ratios in fish muscle tissue of the Truckee River watershed, Nevada, USA

    International Nuclear Information System (INIS)

    The lower Truckee River originates at Lake Tahoe, California/Nevada (NV), USA and ends in the terminal water body, Pyramid Lake, NV. The river has minimal anthropogenic inputs of contaminants until it encounters the cities of Reno and Sparks, NV, and receives inflows from Steamboat Creek (SBC). SBC originates at Washoe Lake, NV, where there were approximately six mills that used mercury for gold and silver amalgamation in the late 1800s. Since then, mercury has been distributed down the creek to the Truckee River. In addition, SBC receives agricultural and urban nonpoint source pollution, and treated effluent from the Reno-Sparks water reclamation facility. Fish muscle tissue was collected from different species in SBC and the Truckee River and analyzed for mercury and stable isotopes. Nitrogen (?δ 15N) and carbon (?δ 13C) isotopic values in these tissues provide insight as to fish food resources and help to explain their relative Hg concentrations. Mercury concentrations, and ?δ 15N and ?δ 13C values in fish muscle from the Truckee River, collected below the SBC confluence, were significantly different than that found in fish collected upstream. Mercury concentrations in fish tissue collected below the confluence for all but three fish sampled were significantly greater (0.1 to 0.65 μg/g wet wt.) than that measured in the tissue collected above the confluence (0.02 to 0.1 μg/g). ?δ 15N and ?δ 13C isotopic values of fish muscle collected from the river below the confluence were higher and lower, respectively, than that measured in fish collected up river, most likely reflecting wastewater inputs. The impact of SBC inputs on muscle tissue isotope values declined down river whereas the impact due to Hg inputs showed the opposite trend

  4. Biology and air-sea gas exchange controls on the distribution of carbon isotope ratios (δ13C) in the ocean

    Science.gov (United States)

    Schmittner, A.; Gruber, N.; Mix, A. C.; Key, R. M.; Tagliabue, A.; Westberry, T. K.

    2013-09-01

    Analysis of observations and sensitivity experiments with a new three-dimensional global model of stable carbon isotope cycling elucidate processes that control the distribution of δ13C of dissolved inorganic carbon (DIC) in the contemporary and preindustrial ocean. Biological fractionation and the sinking of isotopically light δ13C organic matter from the surface into the interior ocean leads to low δ13CDIC values at depths and in high latitude surface waters and high values in the upper ocean at low latitudes with maxima in the subtropics. Air-sea gas exchange has two effects. First, it acts to reduce the spatial gradients created by biology. Second, the associated temperature-dependent fractionation tends to increase (decrease) δ13CDIC values of colder (warmer) water, which generates gradients that oppose those arising from biology. Our model results suggest that both effects are similarly important in influencing surface and interior δ13CDIC distributions. However, since air-sea gas exchange is slow in the modern ocean, the biological effect dominates spatial δ13CDIC gradients both in the interior and at the surface, in contrast to conclusions from some previous studies. Calcium carbonate cycling, pH dependency of fractionation during air-sea gas exchange, and kinetic fractionation have minor effects on δ13CDIC. Accumulation of isotopically light carbon from anthropogenic fossil fuel burning has decreased the spatial variability of surface and deep δ13CDIC since the industrial revolution in our model simulations. Analysis of a new synthesis of δ13CDIC measurements from years 1990 to 2005 is used to quantify preformed and remineralized contributions as well as the effects of biology and air-sea gas exchange. The model reproduces major features of the observed large-scale distribution of δ13CDIC as well as the individual contributions and effects. Residual misfits are documented and analyzed. Simulated surface and subsurface δ13CDIC are influenced by

  5. Biology and air–sea gas exchange controls on the distribution of carbon isotope ratios (δ13C in the ocean

    Directory of Open Access Journals (Sweden)

    A. Schmittner

    2013-09-01

    Full Text Available Analysis of observations and sensitivity experiments with a new three-dimensional global model of stable carbon isotope cycling elucidate processes that control the distribution of δ13C of dissolved inorganic carbon (DIC in the contemporary and preindustrial ocean. Biological fractionation and the sinking of isotopically light δ13C organic matter from the surface into the interior ocean leads to low δ13CDIC values at depths and in high latitude surface waters and high values in the upper ocean at low latitudes with maxima in the subtropics. Air–sea gas exchange has two effects. First, it acts to reduce the spatial gradients created by biology. Second, the associated temperature-dependent fractionation tends to increase (decrease δ13CDIC values of colder (warmer water, which generates gradients that oppose those arising from biology. Our model results suggest that both effects are similarly important in influencing surface and interior δ13CDIC distributions. However, since air–sea gas exchange is slow in the modern ocean, the biological effect dominates spatial δ13CDIC gradients both in the interior and at the surface, in contrast to conclusions from some previous studies. Calcium carbonate cycling, pH dependency of fractionation during air–sea gas exchange, and kinetic fractionation have minor effects on δ13CDIC. Accumulation of isotopically light carbon from anthropogenic fossil fuel burning has decreased the spatial variability of surface and deep δ13CDIC since the industrial revolution in our model simulations. Analysis of a new synthesis of δ13CDIC measurements from years 1990 to 2005 is used to quantify preformed and remineralized contributions as well as the effects of biology and air–sea gas exchange. The model reproduces major features of the observed large-scale distribution of δ13CDIC as well as the individual contributions and effects. Residual misfits are documented and analyzed. Simulated surface and subsurface

  6. Trans-boundary secondary organic aerosol in western Japan indicated by stable carbon isotope ratio of low volatile water-soluble organic carbon and signal at m/z 44 in organic aerosol mass spectra

    CERN Document Server

    Irei, Satoshi; Hayashi, Masahiko; Hara, Keiichiro; Kaneyasu, Naoki; Sato, Kei; Arakaki, Takemitsu; Hatakeyama, Shiro; Hikida, Toshihide; Shimono, Akio

    2013-01-01

    Field studies were conducted in the winter of 2010 at two rural sites and an urban site in western Japan, and filter samples of total suspended particulate matter were collected every 24-h and analyzed for concentration and stable carbon isotope ratio (delta13C) of low volatile water-soluble organic carbon (LV-WSOC). Concentration of major chemical species in fine aerosol (<1.0 micron) was also measured in real time by Aerodyne aerosol mass spectrometers. Oxidation state of organic aerosol was evaluated using the proportion of signal at m/z 44 (fragment ions of carboxyl group) to the sum of all m/z signals of organic mass spectra (f44). Analyses show a high correlation between LV-WSOC and m/z 44 concentrations, suggesting that the LV-WSOC is substantially composed of water soluble carboxylic acids in the fine aerosol. Plots of delta13C of LV-WSOC versus f44 exhibit systematic trends at the rural sites and random variation at the urban site. The systematic trends qualitatively agree with a simple binary mix...

  7. Worldwide lead-isotope ratio in bivalves and sediments

    DEFF Research Database (Denmark)

    Larsen, Martin Mørk; Jacobsen, Gitte; Strand, Jakob;

    The lead-isotope ratio have been used to assess and identify impact of leaded gasoline, coal combustion and  mineral activities[ref 1] due to the difference in 206Pb (~52%), 207Pb (~24%) and 208Pb (~23%) isotope ratios. The source of these differences is the decaying of the parent isotopes of 238U...

  8. Temperature measurements from oxygen isotope ratios of fish otoliths.

    Science.gov (United States)

    Devereux, I

    1967-03-31

    Measurements have shown that the temperature of a fish's habitat can be deduced from the Oxygen isotope ratio of its otoliths (ear bones). Isotope ratios Obtained from fossil otoliths indicate a water temperature which agrees wiht that found by isotope measurements on associated benthonic foraminifera. PMID:6020293

  9. Laser Spectroscopic Measurement of Helium Isotope Ratios

    CERN Document Server

    Wang, L B; Holt, R J; Lu, Z T; O'Connor, T P; Sano, Y; Sturchio, N C

    2003-01-01

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of 3He/4He = 10^-7 - 10^-5. The resonant absorption of 1083 nm laser light by the metastable 3He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of 4He was measured by a direct absorption technique. The results on three different samples extracted from the atmosphere and commercial helium gas were in good agreement with values obtained with mass spectrometry. The achieved 3-sigma detection limit of 3He in helium is 4 x 10^-9. This demonstration required a 200 micro-L STP sample of He. The sensitivity can be further improved, and the required sample size reduced, by several orders of magnitude with the addition of cavity enhanced spectroscopy.

  10. Laser spectroscopic measurement of helium isotope ratios

    International Nuclear Information System (INIS)

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of 3He/4He = 10-7--10-5. The resonant absorption of 1083 nm laser light by the metastable 3He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of 4He was measured by a direct absorption technique. The results on three different samples extracted from the atmosphere and commercial helium gas were in good agreement with values obtained with mass spectrometry. The achieved 3σ detection limit of 3He in helium is 4 x 10-9. This demonstration required a 200 μL STP sample of He. The sensitivity can be further improved, and the required sample size reduced, by several orders of magnitude with the addition of cavity enhanced spectroscopy.

  11. Dissolved organic carbon, CO2, and CH4 concentrations and their stable isotope ratios in thermokarst lakes on the Qinghai-Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Cuicui Mu

    2016-01-01

    Full Text Available Thermokarst lakes are widely distributed on the Qinghai-Tibetan Plateau (QTP, which accounts for 8% of the global permafrost area. These lakes probably promote organic matter biodegradation and thus accelerate the emission of carbon-based greenhouse gases. However, little is known about greenhouse gas concentrations and their stable isotopes characteristics of these lakes. In this study, we measured the concentrations of dissolved organic carbon (DOC, dissolved CO2 and CH4, as well as the distribution of δ13CCO2, δ13CCH4, and δ13COM (organic matter of lake sediments in thermokarst lakes on the QTP. Results showed that the OM of the lake sediments was highly decomposed. The concentrations of DOC, CO2 and CH4 in the lake water on the QTP were 1.2–49.6 mg L–1, 3.6–45.0 μmol L–1 and 0.28–3.0 μmol L–1, respectively. The highest CO2 and CH4 concentrations were recorded in July while the lowest values in September, which suggested that temperature had an effect on greenhouse gas production, although this pattern may also relate to thermal stratification of the water column. The results implied that thermokast lakes should be paid more attention to regarding carbon cycle and greenhouse gas emissions on the QTP.

  12. Seasonal cycles of atmospheric methane and its carbon and hydrogen isotopic ratios in the lower and upper troposphere of the western Pacific region

    Science.gov (United States)

    Umezawa, T.; Aoki, S.; Nakazawa, T.; Machida, T.; Matsueda, H.; Sawa, Y.; Ishijima, K.; Patra, P. K.

    2009-12-01

    Although carbon and hydrogen isotopic ratios (δ13C and δD) of CH4 provide useful information about its sources and sinks, systematic measurements were quite limited. Tohoku University group and NIES group have conducted air-sampling programs by using commercial container ships sailing between Japan and New Zealand and by using commercial airliners flying between Australia and Japan, respectively. Using air samples collected by the programs, systematic measurements of δ13C and δD of atmospheric CH4 as well as CH4 concentration ([CH4]) have been made since 2006. Here, we report their spatial and temporal variations in the lower and upper troposphere (LT and UT). In the LT of the northern hemisphere (NH), the seasonal cycle of [CH4] showed the maximum in winter and the minimum in summer. δ13C varied seasonally almost negatively correlating with the [CH4], and the seasonality of δD showed much more significant negative correlation with the [CH4]. It was also found that CH4 sources with seasonally varying strength, such as wetlands with high emissions in late summer, play an important role in the atmospheric CH4 variations. In the tropics, a seasonally-dependent air exchange between the NH and the southern hemisphere (SH) was found to characterize the seasonal CH4 cycle. When the NH and SH air arrived, high and low [CH4] were observed, accompanied by low and high δ13C and δD values, respectively. In the LT of the SH, the seasonal maximum and minimum of the [CH4] appeared in austral winter and summer, respectively. The seasonal CH4 cycle was mainly ascribed to the seasonality in the CH4+OH reaction, but δ13C and δD showed rather complicated seasonality with larger amplitudes than expected from the CH4+OH reaction alone, suggesting additional contribution of a CH4+Cl reaction in the marine boundary layer. In the UT of the NH, the seasonal maximum and minimum of the [CH4] appeared in summer and winter-spring, respectively, with low and high values of δ13C and

  13. Stable carbon isotope ratio (delta /sup 13/C) of shallow marine bottom sediment as evidence of pollution in Manora channel, Karachi, Pakistan

    International Nuclear Information System (INIS)

    Marine sediments are one of the endpoints for domestic /industrial contaminants from land based sources and provide an archive for tracing pollution record. Contaminated sediment is a significant environmental problem affecting many marine ecosystem. In the present study sediment samples from Manora Channel/Karachi harbour were analyzed for stable isotope composition of inorganic and organic carbon fractions (measured as (delta /sup 13/C) to estimate the land based terrestrial organic matter in the Manora Channel. The principle of this application lies in the fact that delta /sup 13/C values of inorganic carbon (mineral fractions such as calcite, aragonite, dolomite) differs vastly from that of the organic carbon fraction of domestic and/or industrial origin in the sediments. Relatively more depleted delta /sup 13/C (organic) values ranging between - 30.65 to -19.27 - PDB for the organic carbon fraction were found in the Layari river outfall zone. In Manora channel mains enriched values (delta /sup 13/C was found in sediment of Manora lighthouse (-5.0 - PDB) and Pakistan Naval Academy (-11.76 - PDB) while in same zones depleted values of (delta /sup 13/C was found in Bhabba island (-27.31 - PDB), Bhit Island (-26.13 PDB) and Boat Club area (-23.08 PDB) indicating impact of domestic sewage added to the Manora channel from surrounding Islands. (delta /sup 13/C (inorganic) fraction of sediment follow similar trend. In conclusion, this study indicates that the bottom sediments of Karachi Harbour and Layari river outfall zones are mainly polluted with organic waste of domestic origin derived from Layari river. (author)

  14. Constraints on Weathering from Riverine Magnesium Isotope Ratios

    DEFF Research Database (Denmark)

    Wiechert, Uwe; Ullmann, Clemens Vinzenz; Meixner, Anette;

    Weathering of rocks and its impact on the atmospheric carbon budget have been calculated from chemical compositions of large rivers. Here we present chemical compositions and magnesium isotope ratios for the dissolved and suspended loads of the rivers Danube, Elbe, and Rhine, and investigate...... whether magnesium isotopes can contribute to the quantification of weathering rates in their catchments. The d26Mg of the dissolved and solid loads vary from -0.93 to -1.85 ‰ and -0.98 to +0.01 ‰ relative to the reference material DSM3, respectively. Although these rivers run through highly populated...... and industrialized regions, the d26Mg values mirror the lithologies of the catchment areas: the Danubian catchment is dominated by carbonatic lithologies and in the Danube dissolved magnesium exhibits the most negative d26Mg values between -1.85 and -1.70 ‰. The mainly siliceous catchment of the river Elbe causes...

  15. Isotopic ratios at z=0.68 from molecular absorption lines toward B 0218+357

    CERN Document Server

    Wallstrom, S H J; Guelin, M

    2016-01-01

    Isotopic ratios of heavy elements are a key signature of the nucleosynthesis processes in stellar interiors. The contribution of successive generations of stars to the metal enrichment of the Universe is imprinted on the evolution of isotopic ratios over time. We investigate the isotopic ratios of carbon, nitrogen, oxygen, and sulfur through millimeter molecular absorption lines arising in the z=0.68 absorber toward the blazar B 0218+357. We find that these ratios differ from those observed in the Galactic interstellar medium, but are remarkably close to those in the only other source at intermediate redshift for which isotopic ratios have been measured to date, the z=0.89 absorber in front of PKS1830-211. The isotopic ratios in these two absorbers should reflect enrichment mostly from massive stars, and they are indeed close to the values observed toward local starburst galaxies. Our measurements set constraints on nucleosynthesis and chemical evolution models.

  16. Laser ablation molecular isotopic spectrometry of carbon isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Bol' shakov, Alexander A. [Applied Spectra, Inc., Fremont, CA (United States); Jain, Jinesh [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Russo, Richard E. [Applied Spectra, Inc., Fremont, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); McIntyre, Dustin [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Mao, Xianglei [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-08-28

    Quantitative determination of carbon isotopes using Laser Ablation Molecular Isotopic Spectrometry (LAMIS) is described. Optical emission of diatomic molecules CN and C2 is used in these measurements. Two quantification approaches are presented:empirical calibration of spectra using a set of reference standards and numerical fitting of a simulated spectrum to the experimental one. Formation mechanisms of C2 and CN in laser ablation plasma are briefly reviewed to provide insights for implementation of LAMIS measurements. A simulated spectrum of the 12C2 Swan system was synthesized using four constituents within 473.5–476.5 nm. Simulation included three branches of 12C2 (1-0), branches R(0-0) and R(1-1), and branch P(9-8) of 12C2. Spectral positions of the tail lines in R(0-0) and R(1-1) were experimentally measured, since they were not accurately known before. The Swan band (1-0) of the isotopologue 13C12C was also simulated. Fitting to the experimental spectrumyielded the ratio 13C/12C = 1.08% in a good agreement with measurements by isotope ratio mass spectrometry. LAMIS promises to be useful in coal, oil and shale exploration, carbon sequestration monitoring, and agronomy studies

  17. Laser ablation molecular isotopic spectrometry of carbon isotopes

    Science.gov (United States)

    Bol‧shakov, Alexander A.; Mao, Xianglei; Jain, Jinesh; McIntyre, Dustin L.; Russo, Richard E.

    2015-11-01

    Quantitative determination of carbon isotopes using Laser Ablation Molecular Isotopic Spectrometry (LAMIS) is described. Optical emission of diatomic molecules CN and C2 is used in these measurements. Two quantification approaches are presented: empirical calibration of spectra using a set of reference standards and numerical fitting of a simulated spectrum to the experimental one. Formation mechanisms of C2 and CN in laser ablation plasma are briefly reviewed to provide insights for implementation of LAMIS measurements. A simulated spectrum of the 12C2 Swan system was synthesized using four constituents within 473.5-476.5 nm. Simulation included three branches of 12C2 (1-0), branches R(0-0) and R(1-1), and branch P(9-8) of 12C2. Spectral positions of the tail lines in R(0-0) and R(1-1) were experimentally measured, since they were not accurately known before. The Swan band (1-0) of the isotopologue 13C12C was also simulated. Fitting to the experimental spectrum yielded the ratio 13C/12C = 1.08% in a good agreement with measurements by isotope ratio mass spectrometry. LAMIS promises to be useful in coal, oil and shale exploration, carbon sequestration monitoring, and agronomy studies.

  18. Isotope ratio precision analysis using the Varian 820-MS

    International Nuclear Information System (INIS)

    Full text: Scientific disciplines like food chemistry, geochemistry, paleontology are not only interested in the total concentration of an element but also in the isotope ratio of either two isotopes of the same element or isotopes of different elements. The research is focused on elements like selenium, zirconium, strontium, lead and uranium. The knowledge of the isotope ratio 10B/11B is essential for nuclear power plants. In addition to achieve accurate results, the challenge for ICPQMS is to obtain a required precision below 0.1 %. Different approaches to improve the precision of the isotope ratio analysis with ICPQMS are discussed. (author)

  19. Investigations of the ratios of stable carbon isotopes in atmospheric relevant VOC using simulation and field experiments; Untersuchungen der Verhaeltnisse stabiler Kohlenstoffisotope in atmosphaerisch relevanten VOC in Simulations- und Feldexperimenten

    Energy Technology Data Exchange (ETDEWEB)

    Spahn, Holger

    2010-07-01

    Volatile organic compounds (VOC) play an important role in the regional and global atmospheric chemistry. The author of the contribution under consideration reports on the analysis of the ratios of stable carbon isotopes ({delta}({sup 13}C) analysis) in atmospheric VOCs. At first, the state of the art of this analytical technique is described. For the first time {delta}({sup 13}C) values of different monoterpenes have been determined in the investigation of vegetable emissions at a plant chamber. By means of the oxidation of {beta}-pinene by ozone in an aerosol chamber, the kinetic isotope effect of this reaction was determined. In southern Germany, air samples for the {delta}({sup 13}C) analysis were collected using a zeppelin. This enables a height-resolved measurement of {delta}({sup 13}C) values. Based on these measurements, the average photochemical age for methanol, toluene and p-xylene at different heights was calculated.

  20. Photosynthetic isotope fractionation: oxygen and carbon

    International Nuclear Information System (INIS)

    Isotopic carbon analyses of plant tissue and carbon dioxide from air samples and plant and soil respiration were made. Soil respiratory CO2 is about 150/00 lighter than atmospheric CO2. Plant isotopic ratios were found to be influenced by (1) plant photosynthetic efficiency, (2) source CO2, (3) airflow, and (4) CO2 concentrations. Etiolated bean plants have nearly the same delta13C value as seed carbon and seed dark respiratory CO2. Mature leaves from greenhouse grown beans, however, are some 5 0/00 lighter than seed carbon. This is a result of CO2 source, i.e., plant or soil respiratory CO2. Leaves which are generally lighter than other plant organs becomes still lighter during the growing season. As a consequence of increasingly light leaf carbon, photorespired CO2 also becomes lighter during the growing season. Oxygen isotopic values were measured for (1) photorespiratory CO2, which reflects equilibration with leaf water, and (2) photosynthetic O2, which is enriched in 18O, perhaps due to respiratory or photorespiratory 16O preference

  1. Carbon Isotope Chemistry in Molecular Clouds

    Science.gov (United States)

    Robertson, Amy N.; Willacy, Karen

    2012-01-01

    Few details of carbon isotope chemistry are known, especially the chemical processes that occur in astronomical environments like molecular clouds. Observational evidence shows that the C-12/C-13 abundance ratios vary due to the location of the C-13 atom within the molecular structure. The different abundances are a result of the diverse formation pathways that can occur. Modeling can be used to explore the production pathways of carbon molecules in an effort to understand and explain the chemical evolution of molecular clouds.

  2. Tree cellulose 13C/12C isotope ratios and climatic change

    International Nuclear Information System (INIS)

    Because tree cellulose is formed from carbon acquired through photosynthesis, its 13C/12C isotope ratio reflects that of atmospheric CO2. Fractionation changes related to photosynthetic reactions also influence 13C/12C values, and an offset between atmospheric and tree cellulose isotope ratios results. Here, we measured the pre-1850 cellulose 13C/12C isotope ratios of 19 North American coniferous trees and found a strong dependency of the ratios on latitude. Relative humidity and perhaps temperature appear to be important for this relationship. Assuming climate change to be the dominant factor influencing pre-1850 tree cellulose isotope ratios, we compare a 2,000-yr-long record of 13C/12C isotope change with existing records of ice acidity and temperature. When accepting a lag in 13C/12C response to climatic change of 70 to 90 yr, correlation coefficients of 0.8 are found for the 1100–1850 interval

  3. Biology and air–sea gas exchange controls on the distribution of carbon isotope ratios (δ13C in the ocean

    Directory of Open Access Journals (Sweden)

    A. Schmittner

    2013-05-01

    Full Text Available Analysis of observations and sensitivity experiments with a new three-dimensional global model of stable carbon isotope cycling elucidate the processes that control the distribution of δ13C in the contemporary and preindustrial ocean. Biological fractionation dominates the distribution of δ13CDIC of dissolved inorganic carbon (DIC due to the sinking of isotopically light δ13C organic matter from the surface into the interior ocean. This process leads to low δ13CDIC values at dephs and in high latitude surface waters and high values in the upper ocean at low latitudes with maxima in the subtropics. Air–sea gas exchange provides an important secondary influence due to two effects. First, it acts to reduce the spatial gradients created by biology. Second, the associated temperature dependent fractionation tends to increase (decrease δ13CDIC values of colder (warmer water, which generates gradients that oppose those arising from biology. Our model results suggest that both effects are similarly important in influencing surface and interior δ13CDIC distributions. However, air-sea gas exchange is slow, so biological effect dominate spatial δ13CDIC gradients both in the interior and at the surface, in constrast to conclusions from some previous studies. Analysis of a new synthesis of δ13CDIC measurements from years 1990 to 2005 is used to quantify preformed (δ13Cpre and remineralized (δ13Crem contributions as well as the effects of biology (Δδ13Cbio and air–sea gas exchange (δ13C*. The model reproduces major features of the observed large-scale distribution of δ13CDIC, δ13Cpre, δ13Crem, δ13C*, and Δδ13Cbio. Residual misfits are documented and analyzed. Simulated surface and subsurface δ13CDIC are influenced by details of the ecosystem model formulation. For example, inclusion of a simple parameterization of iron limitation of phytoplankton growth rates and temperature-dependent zooplankton grazing rates improves the agreement

  4. Differentiation of endogenous and exogenous steroids by gas chromatography-combustion-mass spectrometry isotope ratio

    International Nuclear Information System (INIS)

    Urinary steroids profiles are used to control the misuse of endogenous steroids such as testosterone and dihydrotestosterone. The testosterone/epistestosterone ratio, measured by Gas Chromatography-Mass Spectrometry, is used to control testosterone administration. When T/E ratio is higher than 4, consumption of testosterone or its precursors is suspected. Recent researches have demonstrated the effectiveness of Carbon Isotope Ratio Mass Spectrometry to detect and confirm endogenous steroids administration. The ratio of the two stable carbon isotopes 13C and 12C allows the differentiation of natural and synthetic steroids because synthetic steroids have lower 13C abundance. In fact, the carbon isotope ratios can be used to determine endogenous steroids administration even when testosterone/epistestosterone ratio is at its normal value. In the current work, some of the most important aspects related to differentiation of endogenous and exogenous steroids by means of Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry are discussed. Also, this article provides a review about the purification and sample preparation previous to the analysis, and diet effects on carbon isotope ratio of endogenous anabolics steroids is presented too

  5. Carbonate Ion Effects on Coccolith Carbon and Oxygen Isotopes

    Science.gov (United States)

    Ziveri, P.; Probert, I.; Stoll, H. M.

    2006-12-01

    The stable oxygen and carbon isotopic composition of biogenic calcite constitutes one of the primary tools used in paleoceanographic reconstructions. The δ18O of shells of ocean floor microfossils and corals reflects the composition of the paleo-seawater as they use the oxygen to build up their calcite and aragonite shells. The δ13C is used to reconstruct variations in the carbon isotopic composition of dissolved inorganic carbon in the ocean, which is controlled by biological productivity through the removal of isotopically light carbon in organic matter. To be effective and sensitive tools for understanding photic zone processes it is first necessary to understand the various biological fractionations associated with carbonate precipitation. To date, isotopic fractionation models are mainly based on foraminifera and corals but not on coccoliths, tiny plates produced by coccolithophore algae, which are often the most dominant carbonate contributors to pelagic sediments. As photosynthetic organisms, their chemistry can provide a sensitive tool for understanding photic zone processes. Coccoliths may be the most important carbonate phase for geochemical analysis in sediments where foraminifera are less common and/or core material is limited, such as in subpolar regions and for Early Cenozoic and Mesozoic sediments. Here we report experimental results on a common living coccolithophore species showing that the 13C/12C and 18O/16O ratios decrease with the increase of HCO^{3-} (CO32-). The selected species are among the heaviest calcifying extant coccolithophores and are major contributors to present coccolith carbonate export production. Because coccolithophores are photosynthetic organisms that calcify intracellularly in specialized vesicles, the challenge lies in ascertaining how kinetic and thermodynamic processes of isotopic fractionation are linked to cellular carbon "transport" and carbonate precipitation. This is a daunting challenge since studies have not

  6. Isotope ratio analysis by a combination of element analyzer and mass spectrometer

    International Nuclear Information System (INIS)

    The use of stable isotope ratios of carbon, nitrogen and sulfur as analytical tool in many fields of research is of growing interest. A method has therefore been developed, consisting in essential of coupling an Elemental Analyzer with an Isotope Mass Spectrometer, which enables the gas preparation of carbon dioxide, nitrogen and sulfur dioxide from any solid or liquid sample in a fast and easy way. Results of carbon isotope measurements in food analysis are presented, whereat it is possible to check origin and treatment of sugar, oils, fats, mineral waters, spirituous liquors etc. and to detect adulterations as well. Also applications in the field of environmental research are given. (Author)

  7. Degradation changes stable carbon isotope depth profiles in palsa peatlands

    Directory of Open Access Journals (Sweden)

    J. P. Krüger

    2014-01-01

    Full Text Available Palsa peatlands are a significant carbon pool in the global carbon cycle and are projected to change by global warming due to accelerated permafrost thaw. Our aim was to use stable carbon isotopes as indicators of palsa degradation. Depth profiles of stable carbon isotopes generally reflect organic matter dynamics in soils with an increase of δ13C values during aerobic decomposition and stable or decreasing δ13C values with depth during anaerobic decomposition. Stable carbon isotope depth profiles of undisturbed and degraded sites of hummocks as well as hollows at three palsa peatlands in northern Sweden were used to investigate the degradation processes. The depth patterns of stable isotopes clearly differ between intact and degraded hummocks at all sites. Erosion and cryoturbation at the degraded sites significantly changes the stable carbon isotope depth profiles. At the intact hummocks the uplifting of peat material by permafrost is indicated by a turning in the δ13C depth trend and this assessment is supported by a change in the C / N ratios. For hollows isotope patterns were less clear, but some hollows and degraded hollows in the palsa peatlands show differences in their stable carbon isotope depth profiles indicating enhanced degradation rates. We conclude that the degradation of palsa peatlands by accelerated permafrost thawing could be identified with stable carbon isotope depth profiles. At intact hummocks δ13C depth patterns display the uplifting of peat material by a change in peat decomposition processes.

  8. Carbon isotope effects in plants related to photosynthesis

    International Nuclear Information System (INIS)

    Plants contain less 13C than the atmosphere due to both enzymatic and physical processes that discriminate against the heavier isotope in favour of the lighter one. These differences have allowed us to use isotopic signature to identify photosynthetic pathways of many plant species. The purpose of this study is to present a method for measuring the carbon isotope discrimination in the leaf of the plant. We carried out conversion of organic sample from two species (Prunus amygdalus and Rosa) to CO2 by dry combustion in an excess of oxygen. The stable carbon isotope ratio (13C/12C) was measured with high precision by a mass spectrometer. This isotopic discrimination was used to assess the ratio of intercellular to atmospheric CO2 concentration, ci/ca. We plan to use the isotopic discrimination to estimate plant water-use efficiency, a relevant parameter for conferring tolerance of the plant to environmental stress. (authors)

  9. Indications for pedogenic formation of perylene in a terrestrial soil profile: Depth distribution and first results from stable carbon isotope ratios

    International Nuclear Information System (INIS)

    Concentrations and isotope compositions of polycyclic aromatic hydrocarbons (PAHs) were determined in natural soils of Southern Germany. In selected profiles perylene concentrations increased with soil depth when compared to the other PAH compounds present. However, its low solubility made vertical transport by seepage water unlikely. Therefore two mechanisms are discussed that could have caused the unusual distribution of perylene in these soils: (a)Atmospheric deposition of combustion-derived (i.e. pyrogenic) perylene in the top-soil and (b)in situ generation in the sub-soil of these specific terrestrial environments. This could have been caused by microbial activities or other catalytic processes yet unknown. In order to distinguish between pyrogenic and natural generation compound-specific 13C/12C ratios (δ13C) were compared between perylene and other PAHs in samples from the top-soil and sub-soil. Despite successful clean-up of the extracts, low perylene concentrations and peak overlaps with benzo(e)pyrene and benzo(a)pyrene prevented determination of a unique δ13C value for perylene in the upper horizon. However, the δ13C value of perylene in the sub-soil was 5.7 permille more negative than other equal-mass PAHs (with m/z of 252) in the top-soil, which rather supports in situ generation of perylene in the sub-soil

  10. Determination of fission gas yields from isotope ratios

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg

    1983-01-01

    This paper describes a method of calculating the actual fission yield of Kr and Xe in nuclear fuel including the effect of neutron capture reactions and decay. The bases for this calculation are the cumulative yields (ref. 1) of Kr and Xe isotopes (or pairs of isotopes) which are unaffected by...... neutron capture reactions, and measured Kr and Xe isotope ratios. Also the burnup contribution from the different fissile heavy isotopes must be known in order to get accurate fission gas yields....

  11. Stable-carbon isotope variability in tree foliage and wood

    International Nuclear Information System (INIS)

    This study documents variation of stable-carbon isotope ratios (13C/12C) in trees of genera Juniperus and Pinus under field conditions. Results are from cellulose analysis on leaves, twigs, and wood from a number of localities in the southwestern US. Substantial variability, typically 1-3%, exists among leaves, within wood (radially, vertically, circumferentially), and between individuals at a site. These results may help guide sampling in tracer-type studies with stable-carbon isotope ratios and aid in the interpretation of isotopic results from such studies

  12. Ecophysiological comportment of the tropical C3/CAM-intermediate tree Clusia rosea in the field as assessed by analysis of stable carbon- and hydrogen-isotope ratios

    International Nuclear Information System (INIS)

    Grown-up trees of C. rosea (girths larger than 7 cm, heights taller than 2 m) in the Virgin Islands have a strong component of nocturnal CAM-type CO2 fixation as indicated by their δ13C values of ≈ −18‰ reaching up to the low end of the range typical for CAM (−9 to −18‰). Seedlings (girths up to 3.5em and heights up to 1.2m) have a smaller but still notable CO2-dark fixation as suggested by ODC values of ≈ −21 to ≈ −26‰, and only very small seedlings appear to be exclusively C3 (δ13C = −29‰). The larger variation of δ13C-values among seedlings suggests that seedlings make more flexible use of the options of CO2 dark- and light-fixation than adult trees, while the larger variation of δD-values among trees supports the conclusion, that overall the trees are more flexible in their use of water in transpiration. More negative values of δ13C and δD in terrestrial plants as compared to their epiphytic sympatriotes suggest that the ratio of dark fixation to light fixation of CO2 is smaller in terrestrial plants and that epiphytic plants transpire more of the water available to them. Leaf-N levels support the assumption of a better supply of the terrestrial plants. The analyses of stable isotopes and leaf-N levels, which are very suitable for screening in the field, corroborate the high ecophysiological flexibility of C. rosea as shown by more elaborate experimental approaches in the laboratory and in the field. (author)

  13. Stable oxygen and hydrogen isotopes of brines - comparing isotope ratio mass spectrometry and isotope ratio infrared spectroscopy

    Science.gov (United States)

    Ahrens, Christian; Koeniger, Paul; van Geldern, Robert; Stadler, Susanne

    2013-04-01

    Today's standard analytical methods for high precision stable isotope analysis of fluids are gas-water equilibration and high temperature pyrolysis coupled to isotope ratio mass spectrometers (IRMS). In recent years, relatively new laser-based analytical instruments entered the market that are said to allow high isotope precision data on nearly every media. This optical technique is referred to as isotope ratio infrared spectroscopy (IRIS). The objective of this study is to evaluate the capability of this new instrument type for highly saline solutions and a comparison of the analytical results with traditional IRMS analysis. It has been shown for the equilibration method that the presence of salts influences the measured isotope values depending on the salt concentration (see Lécuyer et al, 2009; Martineau, 2012). This so-called 'isotope salt effect' depends on the salt type and salt concentration. These factors change the activity in the fluid and therefore shift the isotope ratios measured by the equilibration method. Consequently, correction factors have to be applied to these analytical data. Direct conversion techniques like pyrolysis or the new laser instruments allow the measurement of the water molecule from the sample directly and should therefore not suffer from the salt effect, i.e. no corrections of raw values are necessary. However, due to high salt concentrations this might cause technical problems with the analytical hardware and may require labor-intensive sample preparation (e.g. vacuum distillation). This study evaluates the salt isotope effect for the IRMS equilibration technique (Thermo Gasbench II coupled to Delta Plus XP) and the laser-based IRIS instruments with liquid injection (Picarro L2120-i). Synthetic salt solutions (NaCl, KCl, CaCl2, MgCl2, MgSO4, CaSO4) and natural brines collected from the Stassfurt Salt Anticline (Germany; Stadler et al., 2012) were analysed with both techniques. Salt concentrations ranged from seawater salinity

  14. Isotope analysis of carbon by C2 molecule spectrum

    International Nuclear Information System (INIS)

    A study was made on inert gas mixture (He, Ne, Ar) with carbon-containing components (CO, CO2, CH4) under conditions of variation of mixture pressure in discharge tube, of carbon-containing components contents and the rate of gas flow through the discharge tube. The use of C2 molecule spectrum enabled to develope the spectroscopic techniques for determination of carbon isotope ratio. The method is universal with respect to molecular form of carbon-containing substance

  15. Stable isotope ratio mass spectrometry in forensic science and food adulteration research

    International Nuclear Information System (INIS)

    Stable Isotope Ratio Mass Spectrometry (SIRMS) is an established technique for the determination of origin of geological, biological, chemical and physio-chemical samples/materials. With the development of highly precise mass spectrometers, the stable isotope ratio determination of hydrogen, carbon, nitrogen and oxygen have gained considerable interest in the fields of forensic science and food authentication. Natural variations in the isotopic composition of lighter elements occur due to fractionation effects, resulting in the finger printing of specific isotope ratio values that are characteristic of the origin, purity, and manufacturing processes of the products and their constituents. Forensic science uses scientific and technical methods to investigate traceable evidence of criminal acts. Stable isotope ratio mass spectrometry has been applied to numerous aspects of the forensic science. The analysis of explosives such as ammonium nitrate, gun powder and tri-nitro-toluene (TNT), cases of murder, armed robbery, drug smuggling, terrorism, arson and hit and run traffic accidents are a few of them. The main types of geological evidences in such cases are mud, soil, rocks, sand, gravel, dust particles, biological materials, organic particles and anthropogenic components. Stable isotopes are used as tools to corroborate and confirm the evidential leads in the investigation of such crimes. The variation in natural abundances of carbon and nitrogen and their isotopic ratios δ13C and δ15N can identify links between items found at crime scene with those of suspect. The paper discusses the applications of SIRMS in the field of forensic science and food adulteration research

  16. Oxygen isotope fractionation in divalent metal carbonates

    Science.gov (United States)

    O'Neil, J.R.; Clayton, R.N.; Mayeda, T.K.

    1969-01-01

    Equilibrium fractionation factors for the distribution of 18O between alkaline-earth carbonates and water have been measured over the temperature range 0-500??C. The fractionation factors ?? can be represented by the equations CaCO3-H2O, 1000 ln??=2.78(106 T-2)-3.39, SrCO3-H 2O, 1000 ln??=2.69(106 T-2)-3.74, BaCO3-H2O, 1000 ln??=2.57(106 T -2)-4.73. Measurements on MnCO3, CdCO3, and PbCO3 were made at isolated temperatures. A statistical-mechanical calculation of the isotopic partition function ratios gives reasonably good agreement with experiment. Both cationic size and mass are important in isotopic fractionation, the former predominantly in its effect on the internal vibrations of the anion, the latter in its effect on the lattice vibrations.

  17. THE ATOMIC WEIGHTS COMMISSION AND ISOTOPIC ABUNDANCE RATIO DETERMINATIONS.

    Energy Technology Data Exchange (ETDEWEB)

    HOLDEN, N.E.

    2005-08-07

    Following Thomson's discovery of stable isotopes in non-radioactive chemical elements, the derivation of atomic weight values from mass spectrometric measurements of isotopic abundance ratios moved very slowly. Forty years later, only 3 1/2 % of the recommended values were based on mass spectrometric measurements and only 38% in the first half century. It might be noted that two chemical elements (tellurium and mercury) are still based on chemical measurements, where the atomic weight value calculated from the relative isotopic abundance measurement either agrees with the value from the chemical measurement or the atomic weight value calculated from the relative isotopic abundance measurement falls within the uncertainty of the chemical measurement of the atomic weight. Of the 19 chemical elements, whose atomic weight is based on non-corrected relative isotopic abundance measurements, five of these are two isotope systems (indium, iridium, lanthanum, lutetium and tantalum) and one is a three-isotope system (oxygen).

  18. Metal Concentrations in the Liver and Stable Isotope Ratios of Carbon and Nitrogen in the Muscle of Silvertip Shark (Carcharhinus albimarginatus) Culled off Ishigaki Island, Japan: Changes with Growth.

    Science.gov (United States)

    Endo, Tetsuya; Kimura, Osamu; Ohta, Chiho; Koga, Nobuyuki; Kato, Yoshihisa; Fujii, Yukiko; Haraguchi, Koichi

    2016-01-01

    We analyzed Hg, Cd, Zn, Cu and Fe concentrations in liver samples as well as the Hg concentration and stable isotope ratios of carbon and nitrogen (δ13C and δ15N) in muscle samples from silvertip sharks (Carcharhinus albimarginatus) in Japan. Muscular and hepatic Hg concentrations increased with increased body length. However, these increases were more prominent in the liver than in the muscle samples, and appeared to occur after maturation. Hepatic Zn and Cu concentrations decreased during the growth stage, and then increased concomitantly thereafter with increases in Cd burden. Hepatic Fe concentration from males increased proportionally with increases in body length, whereas no increase was observed in samples from females, probably due to the mother-to-embryo transfer of Fe. The δ13C values tended to decrease with increases in body length, whereas no decrease in the δ15N values was observed. PMID:26859569

  19. Metal Concentrations in the Liver and Stable Isotope Ratios of Carbon and Nitrogen in the Muscle of Silvertip Shark (Carcharhinus albimarginatus Culled off Ishigaki Island, Japan: Changes with Growth.

    Directory of Open Access Journals (Sweden)

    Tetsuya Endo

    Full Text Available We analyzed Hg, Cd, Zn, Cu and Fe concentrations in liver samples as well as the Hg concentration and stable isotope ratios of carbon and nitrogen (δ13C and δ15N in muscle samples from silvertip sharks (Carcharhinus albimarginatus in Japan. Muscular and hepatic Hg concentrations increased with increased body length. However, these increases were more prominent in the liver than in the muscle samples, and appeared to occur after maturation. Hepatic Zn and Cu concentrations decreased during the growth stage, and then increased concomitantly thereafter with increases in Cd burden. Hepatic Fe concentration from males increased proportionally with increases in body length, whereas no increase was observed in samples from females, probably due to the mother-to-embryo transfer of Fe. The δ13C values tended to decrease with increases in body length, whereas no decrease in the δ15N values was observed.

  20. Reconstruction of floral changes during deposition of the Miocene Embalut coal from Kutai Basin, Mahakam Delta, East Kalimantan, Indonesia by use of aromatic hydrocarbon composition and stable carbon isotope ratios of organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Widodo, S.; Bechtel, A.; Anggayana, K.; Puttmann, W. [University of Frankfurt, Frankfurt (Germany)

    2009-02-15

    The distribution of aromatic hydrocarbons and stable carbon isotope ratios of organic matter in a series of nine Miocene Embalut coal samples obtained from nine coal seams of Kutai Basin, East Kalimantan, Indonesia were studied. The rank of the Embalut coals ranged from lignites to low rank sub-bituminous coals (0.36-0.50% Rr), based on measurements of huminite reflectance. The aromatic hydrocarbon fractions of all coal samples were dominated by cadalene in the lower boiling point range and picene derivatives in the higher boiling point range of the gas chromatograms. Cadalene can be attributed to the contribution of Dipterocarpaceae and various hydrated picenes to the contribution of additional angiosperms to the coal forming vegetation. The picenes originate from {alpha}- and {beta}-amyrin. However, in some coal samples minor amounts of simonellite and retene were also detected which argues for an additional contribution of gymnosperms (conifers) to coal forming vegetation preferentially in the Middle Miocene and at the beginning of the Late Miocene. The results of stable carbon isotope ratios ({delta}{sup 13}C in most of the coal samples are consistent with their origin from angiosperms {delta}{sup 13}C between -27.09, and -28.0%). During the Miocene the climate of Mahakam Delta was not uniformly moist and cooler than the present day climate. This would have been favourable for the growth of conifers, especially in the montane forests. The contribution of conifers to the Embalut coals might be a result of the cool Middle/Late Miocene climate during peat accumulation in the Kutai Basin.

  1. Carbon isotope effects in carbonate systems

    Science.gov (United States)

    Deines, Peter

    2004-06-01

    Global carbon cycle models require a complete understanding of the δ 13C variability of the Earth's C reservoirs as well as the C isotope effects in the transfer of the element among them. An assessment of δ 13C changes during CO 2 loss from degassing magmas requires knowledge of the melt-CO 2 carbon isotope fractionation. In order to examine the potential size of this effect for silicate melts of varying composition, 13C reduced partition functions were computed in the temperature range 275 to 4000 K for carbonates of varying bond strengths (Mg, Fe, Mn, Sr, Ba, Pb, Zn, Cd, Li, and Na) and the polymorphs of calcite. For a given cation and a given pressure the 13C content increases with the density of the carbonate structure. For a given structure the tendency to concentrate 13C increases with pressure. The effect of pressure (‰/10 kbar) on the size of the reduced partition function of aragonite varies with temperature; in the pressure range 1 to 10 5 bars the change is given by: Δ 13C p average=-0.01796+0.06635∗ 10 3/T+0.006875∗ 10 6/T2 For calcite III the pressure effect is on average 1.4× larger than that for aragonite at all temperatures. The nature of the cation in a given structure type has a significant effect on the carbon isotope fractionation properties. The tendency to concentrate 13C declines in the series magnesite, aragonite, dolomite, strontianite, siderite, calcite, smithonite, witherite, rhodochrosite, otavite, cerrusite. For divalent cations a general expression for an estimation of the reduced partition function (β) from the reduced mass (μ = [M Cation × M Carbonate]/[M Cation + M Carbonate]) is: 1000 lnβ=(0.032367-0.072563∗ 10 3/T-0.01073∗ 10 6/T2)∗μ-14.003+29.953∗ 10 3/T+9.4610∗ 10 6/T2 For Mg-calcite the 13C content varies with the Mg concentration. The fractionation between Mg-calcite (X = mole fraction of MgCO 3) and calcite is given by: 1000 ln(α MgCalite- Calcite)=[0.013702-0.10957× 10 3/T+1.35940× 10 6/T2

  2. Stable isotope ratios and sulphate/methane interaction in lakes

    International Nuclear Information System (INIS)

    , especially as compared to the corresponding low sulphate concentration. This may suggest that the sulphate concentration violated individual biological abilities of lakes to buffer the anthropogenic sulphate. In the SE Poland, where the anthropogenic impact is limited, one may believe also that a significant portion of sulphate in mountainous lakes is of oceanic origin (34S-enriched oceanic spray). This could be especially valid for Czarny Staw lake (1650 m asl), which is highly oligotrophic, without any signs of ongoing reduction, and negligible photosynthetic processes in the high mountains area above the lake (no source of organic matter). On the other hand, reoxidation of S2- -bearing compounds, in the presence of 18O depleted mountainous water can be expected. This process could be important in SW Poland lakes, where anthropogenic SO2 impact is extremely high. The importance of red-ox processes in these lakes may be supported by isotope study of bubble methane (n = c.a. 400). Mechanisms of methanogenesis and potential oxidation of methane are main factors controlling concentration and isotope ratio in methane. Likewise, sulphate is the main oxidant of methane and the methane precursors. In contrast to the other lakes, the observed negative correlation in the system δ13C(CH4) - depth of the water column, may be the result of the strong contamination by the SO42-, exceeding the biological buffering abilities of the lake. Conclusions 1. Most lakes show an individual δ34S and δ18O signal and relatively little variations. It reflects trophy, red-ox and individual buffering potential for acid rain contamination 2. In contrast to not contaminated lakes, a higher carbon isotope ratios in methane at depths may result from strong contamination with sulphate ion

  3. Economically important applications of carbon isotope data of natural gases and crude oil: a brief review

    International Nuclear Information System (INIS)

    Carbon isotope fractionations in hydrocarbons are briefly reviewed and examples of practical applications in the exploration of crude oil are given. Carbon isotope fractionations of natural gases are discussed. It is shown that the carbon isotope ratio of methane is predominantly determined by the environment (humic or sapropelic) and the maturity of its organic source material. In this way, isotope analyses of natural gases can be quantitatively used to characterize the maturity of their source rocks. (author)

  4. Robust optical carbon dioxide isotope analyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Isotopic analysis of carbon dioxide is an important tool for characterization of the exchange and transformation of carbon between the biosphere and the atmosphere....

  5. Isotope analytics for the evaluation of the feeding influence on the isotope ratio in beef samples; Isotopenanalytik zur Bestimmung des Einflusses der Ernaehrung auf die Isotopenzusammensetzung in Rinderproben

    Energy Technology Data Exchange (ETDEWEB)

    Herwig, Nadine

    2010-11-17

    Information about the origin of food and associated production systems has a high significance for food control. An extremely promising approach to obtain such information is the determination of isotope ratios of different elements. In this study the correlation of the isotope ratios C-13/C-12, N-15/N-14, Mg-25/Mg-24, and Sr-87/Sr-86 in bovine samples (milk and urine) and the corresponding isotope ratios in feed was investigated. It was shown that in the bovine samples all four isotope ratios correlate with the isotope composition of the feed. The isotope ratios of strontium and magnesium have the advantage that they directly reflect the isotope ratios of the ingested feed since there is no isotope fractionation in the bovine organism which is in contrast to the case of carbon and nitrogen isotope ratios. From the present feeding study it is evident, that a feed change leads to a significant change in the delta C-13 values in milk and urine within 10 days already. For the deltaN-15 values the feed change was only visible in the bovine urine after 49 days. Investigations of cows from two different regions (Berlin/Germany and Goestling/Austria) kept at different feeding regimes revealed no differences in the N-15/N-14 and Mg-26/Mg-24 isotope ratios. The strongest correlation between the isotope ratio of the bovine samples and the kind of ingested feed was observed for the carbon isotope ratio. With this ratio even smallest differences in the feed composition were traceable in the bovine samples. Since different regions usually coincide with different feeding regimes, carbon isotope ratios can be used to distinguish bovine samples from different regions if the delta C-13 values of the ingested feed are different. Furthermore, the determination of strontium isotope ratios revealed significant differences between bovine and feed samples of Berlin and Goestling due to the different geologic realities. Hence the carbon and strontium isotope ratios allow the best

  6. Pu600 energy window arithmetic of plutonium isotopes ratio

    International Nuclear Information System (INIS)

    The idea of calculating plutonium isotopes ratio using Pu600 energy window (630-670 keV) was put forward by the LLNL. And plutonium isotopes ratio arithmetic on Pu600 energy window was developed in this paper. Some γ energy spectra of two plutonium samples were calculated on this arithmetic, and the results are consistent with the results from PC/FRAM. (authors)

  7. Characterization of the origin of coalbed gases in southeastern Illinois Basin by compound-specific carbon and hydrogen stable isotope ratios

    Science.gov (United States)

    Strapoc, D.; Mastalerz, Maria; Eble, C.; Schimmelmann, A.

    2007-01-01

    Coalbed gases and waters from exploratory and production gas wells in the southeastern Illinois Basin were sampled to assess geochemically the origin of coalbed gases, with an emphasis on the Springfield and Seelyville Coal Members that are commercially targeted for coalbed methane production in Indiana. On-line analyses of hydrocarbon gases methane to butanes (C1, C2, C3, n-C4, i-C4) and CO2 yielded gas concentrations, plus ??D and ??13C values. The low thermal maturity of Indiana coals with vitrinite reflectance R0 ??? 0.6% is in agreement with an overwhelmingly biogenic isotopic signature of coalbed gases containing ???96% methane generated via bacterial CO2-reduction. In contrast, thermogenic gas was generated in the stratigraphically equivalent coal beds in western Kentucky's Rough Creek Graben zone where higher maturities of up to R0 ??? 0.8% were reached owing to tectonic and hydrothermal activity. No secondary biogenic methane was observed in more mature western Kentucky coal beds where greater burial depth limits the recharge of meteoric water. Biogenic and thermogenic coalbed gases represent two end-members that are compositionally and isotopically distinct. Microbial biodegradation of thermogenic C2+ hydrocarbon gases in Indiana coal beds preferentially targets C3 and introduces isotope fractionation whereby remaining C3 is enriched in deuterium and 13C.

  8. Development of TIMS for isotopic ratio analysis of boron

    International Nuclear Information System (INIS)

    A magnetic sector based Thermal Ionisation Mass Spectrometer (TIMS) has been developed at Technical Physics Division, for high precision isotope ratio analysis of Boron (in the form of Sodium Meta-borate) at the Boron enrichment facility, Heavy Water Plant, Manuguru. The performance of this indigenously developed TIMS has been tested for sensitivity, isotope ratio precision and accuracy for different levels of enrichment in the plant samples. The sensitivity of this instrument was found to be 1 ion per 200 atoms. The internal and external precision for natural concentration levels Boron isotopes were better than 0.05%. (author)

  9. Isotope yield ratios as a probe of the reaction dynamics

    International Nuclear Information System (INIS)

    Isotopically resolved yields of particles and complex fragments from 12C and 18O induced reactions on 53Ni, 54Ni, Ag, and 197Au in the intermediate range of bombarding energies 30 MeV ≤ E/A ≤ 84 MeV were measured. The systematic variation of the deduced isotope yield ratios with projectile and target is used to determine the degree of N/Z equilibration achieved and to establish time scales for the reaction process. A quantum statistical model is employed in order to derive entropies of the emitting systems from the measured isotope yield ratios. (orig.)

  10. Carbon isotope effects associated with aceticlastic methanogenesis

    Science.gov (United States)

    Gelwicks, J. T.; Risatti, J. B.; Hayes, J. M.

    1994-01-01

    The carbon isotope effects associated with synthesis of methane from acetate have been determined for Methanosarcina barkeri 227 and for methanogenic archaea in sediments of Wintergreen Lake, Michigan. At 37 degrees C, the 13C isotope effect for the reaction acetate (methyl carbon) --> methane, as measured in replicate experiments with M. barkeri, was - 21.3% +/- 0.3%. The isotope effect at the carboxyl portion of acetate was essentially equal, indicating participation of both positions in the rate-determining step, as expected for reactions catalyzed by carbon monoxide dehydrogenase. A similar isotope effect, - 19.2% +/- 0.3% was found for this reaction in the natural community (temperature = 20 degrees C). Given these observations, it has been possible to model the flow of carbon to methane within lake sediment communities and to account for carbon isotope compositions of evolving methane. Extension of the model allows interpretation of seasonal fluctuations in 13C contents of methane in other systems.

  11. Stable carbon isotope analysis of bone apatite

    International Nuclear Information System (INIS)

    The application of stable carbon isotope analysis to bone apatite is investigated. Bone apatite was prepared from 28 samples of 5 species of modern browsing herbivores, and their 13C/12C ratios measured. The δ13C values for bone apatite of the modern specimens shows a mean enrichment of +12 o/oo relative to the C3 dietary mean of -26.5o/oo. The values for T. strepsiceros (kudu) suggest that it is not a consistent browzer, as was formerly believed. Seven fossil bone apatite browzer samples gave δ13C values which fell within the range for the modern samples. It is concluded that the 13C/12C ratio in modern bone apatite accurately reflects diet, but data for fossil samples was insufficient to allow a firm conclusion about the reliability of bone apatite dietary tracing in archaeological contexts

  12. Carbon and oxygen isotope compositions of the carbonate facies in the Vindhyan Supergroup, central India

    Indian Academy of Sciences (India)

    S Banerjee; S K Bhattacharya; S Sarkar

    2006-02-01

    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 subtle controls of facies variation,depositional setting and post-depositional diagenesis on stable isotope compositions are not yet clearly understood.The Vindhyan Super- group hosts four carbonate units,exhibiting a wide variability in depositional processes and paleogeography.A detailed facies-specific carbon and oxygen isotope study of the carbonate units was undertaken by us to investigate the effect of these processes and to identify the least altered isotope values.It is seen that both carbon and oxygen isotope compositions have been affected by early meteoric water diagenesis.The effect of diagenetic alteration is,however,more pronounced in case of oxygen isotopes than carbon isotopes.Stable isotope compositions remained insensitive to facies only when sediments accumulated in a shallow shelf setting without being exposed.Major alteration of original isotope ratios was observed in case of shallow marine carbonates,which became exposed to meteoric fluids during early diagenetic stage.Duration of exposure possibly determined the magnitude of alteration and shift from the original values.Moreover,dolomitization is found to be accompanied by appreciable alteration of isotope compositions in some of the carbonates.The present study suggests that variations in sediment depositional settings,in particular the possibility of subaerial exposure,need to be considered while extracting chronostratigraphic signi ficance from 13C data.

  13. D/H Isotope Ratio Measurements of Atmospheric Volatile Organic Compounds

    Science.gov (United States)

    Meisehen, Thomas; Bühler, Fred; Koppmann, Ralf; Krebsbach, Marc

    2015-04-01

    Analysis of isotope ratios in atmospheric volatile organic compounds (VOC) is a reliable method to allocate their sources, to estimate atmospheric residence times and investigate physical and chemical processes on various temporal and spatial scales. Most investigations yet focus on carbon isotope ratios. Certainly more detailed information can be gained by the ratio of deuterium (D) to hydrogen (H) in VOC, especially due to the high mass ratio. Combining measurements of carbon and hydrogen isotopes could lead to considerable improvement in our understanding of atmospheric processes. For this purpose we set up and thoroughly characterised a gas chromatograph pyrolysis isotope ratio mass spectrometer to measure the D/H ratio in atmospheric VOC. From a custom-made gas standard mixture VOC were adsorbed on Tenax®TA which has the advantage that CO2 is not preconcentrated when measuring ambient air samples. Our results show that the pyrolysis method has significant impact on the D/H ratios. A pyrolysis temperature of at least 1723 K and conditioning of the ceramic tube on a regular basis is essential to obtain reproducible D/H isotope ratios. For an independent comparison D/H ratios of the pure VOC used in the gas standard were determined using elemental analysis by Agroisolab (Jülich, Germany). Comparisons of 10 VOC show perfect agreement within the standard deviations of our measurements and the errors given by Agroisolab, e.g. for n-pentane, toluene, 4-methyl-2-pentanone and n-octane. A slight mean difference of 5.1 o was obtained for n-heptane while significant mean differences of 15.5 o and 20.3 o arose for 1,2,4-trimethylbenzene and isoprene, respectively. We further demonstrate the stability of our system and show that the sample preparation does not affect the isotope ratios. Moreover the applicability of our system to ambient air samples is demonstrated.

  14. Determining lead sources in Mexico using the lead isotope ratio

    Directory of Open Access Journals (Sweden)

    Chaudhary-Webb Madhu

    2003-01-01

    Full Text Available OBJECTIVE: Lead poisoning can, in some cases, be traced to a specific route or source of exposure on the basis of the individual's blood lead isotope ratio. To assess the major source of lead exposure among women residing in Mexico City, we compared blood, ceramic, and gasoline lead isotope ratios. MATERIAL AND METHODS: The study population, randomly selected from participants of a large trial, (1/1996-12/1996 comprised of 16 women whose lead levels exceeded 10 µg/dl and who reported using lead-glazed ceramics. Lead isotope ratios were performed on a Perkin Elmer 5000 Inductively Coupled Plasma Mass Spectrometer (ICP-MS interfaced with a Perkin Elmer HGA-600MS Electrothermal Vaporization System (ETV. RESULTS: The isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb of both the blood specimens and their corresponding ceramic specimens were highly correlated, with r=0.9979, r²=0.9958, r=0.9957, r²=0.9915 and r=0.9945, r²=0.9890 values for the three isotope ratios, respectively, suggesting that the lead exposure most likely resulted from the use of these ceramic. Measurements of lead isotope ratios from leaded gasoline in use at the time of blood sampling, differed from those in blood and ceramics. CONCLUSIONS: Determining lead isotope ratios can be an efficient tool to identify a major source of lead exposure and to support the implementation of public health prevention and control measures.

  15. Chlorine Isotope Effects from Isotope Ratio Mass Spectrometry Suggest Intramolecular C-Cl Bond Competition in Trichloroethene (TCE Reductive Dehalogenation

    Directory of Open Access Journals (Sweden)

    Stefan Cretnik

    2014-05-01

    Full Text Available Chlorinated ethenes are prevalent groundwater contaminants. To better constrain (biochemical reaction mechanisms of reductive dechlorination, the position-specificity of reductive trichloroethene (TCE dehalogenation was investigated. Selective biotransformation reactions (i of tetrachloroethene (PCE to TCE in cultures of Desulfitobacterium sp. strain Viet1; and (ii of TCE to cis-1,2-dichloroethene (cis-DCE in cultures of Geobacter lovleyi strain SZ were investigated. Compound-average carbon isotope effects were −19.0‰ ± 0.9‰ (PCE and −12.2‰ ± 1.0‰ (TCE (95% confidence intervals. Using instrumental advances in chlorine isotope analysis by continuous flow isotope ratio mass spectrometry, compound-average chorine isotope effects were measured for PCE (−5.0‰ ± 0.1‰ and TCE (−3.6‰ ± 0.2‰. In addition, position-specific kinetic chlorine isotope effects were determined from fits of reactant and product isotope ratios. In PCE biodegradation, primary chlorine isotope effects were substantially larger (by −16.3‰ ± 1.4‰ (standard error than secondary. In TCE biodegradation, in contrast, the product cis-DCE reflected an average isotope effect of −2.4‰ ± 0.3‰ and the product chloride an isotope effect of −6.5‰ ± 2.5‰, in the original positions of TCE from which the products were formed (95% confidence intervals. A greater difference would be expected for a position-specific reaction (chloride would exclusively reflect a primary isotope effect. These results therefore suggest that both vicinal chlorine substituents of TCE were reactive (intramolecular competition. This finding puts new constraints on mechanistic scenarios and favours either nucleophilic addition by Co(I or single electron transfer as reductive dehalogenation mechanisms.

  16. Isotope ratios as pollutant source and behaviour indicators

    International Nuclear Information System (INIS)

    Recent years have witnessed significant advances in isotope techniques for identifying origins and for studying the behaviour of trace contaminants and pollutants of the environment under actual existing environmental conditions. Improvements in the supply of stable isotopes and their labelled compounds, instrumental analysis and information on stable or radioactive isotopic ratios of existing environmental contaminants as a function of origin or behaviour have provided relatively new tools for the environmental scientist. While variations in natural or existing environmental stable and radioactive nuclides could be regarded as 'background noise' in conventional tracer experiments they promised unique information about sources and behaviour to those who listened carefully. (author)

  17. Spatial variability of carbon13C) and nitrogen (δ15N) stable isotope ratios in an Arctic marine food web

    DEFF Research Database (Denmark)

    Hansen, Joan Holst; Hedeholm, Rasmus Berg; Sünksen, Kaj;

    2012-01-01

    Stable isotopes of carbon (δ13C) and nitrogen (δ15N) were used to examine trophic structures in an arctic marine food web at small and large spatial scales. Twelve species, from primary consumers to Greenland shark, were sampled at a large spatial scale near the west and east coasts of Greenland...... illustrate the importance of spatial variability when interpreting trophic structure from stable isotopes......., attributing some of the variation to physical and biological sources. Hence, significant differences in isotopic signatures on both large and small spatial scales were less related to food web structure than to different physical and biological properties of the water masses. Accordingly, the results...

  18. Tracing gas accretion in the Galactic center using isotopic ratios

    CERN Document Server

    Riquelme, D; Martin-Pintado, J; Mauersberger, R; Martin, S; Bronfman, L

    2010-01-01

    Ams: We study the 12C/13C isotopic ratio in the disk of the central molecular zone and in the halo to trace gas accretion toward the Galactic center region in the Milky Way. Methods: Using the IRAM 30m telescope, we observe the J=1-0 rotational transition of HCO+, HCN, HNC and their 13C isotopic substitutions in order to measure the 12C/13C isotopic ratio. We observe 9 positions selected throughout the Galactic center region, including clouds at high latitude; locations where the X1 and X2 orbits associated with the barred potential are expected to intersect; and typical Galactic center molecular clouds. Results: We find a systematically higher 12C/13C isotopic ratio (>40) toward the halo and the X1 orbits than for the Galactic center molecular clouds (20-25). Our results point out to molecular gas which has undergone a different degree of nuclear processing than that observed in the gas towards the inner Galactic center region. Conclusions: The high isotopic ratios are consistent with the accretion of the ga...

  19. Calcium isotope ratios in animal and human bone

    Science.gov (United States)

    Reynard, L. M.; Henderson, G. M.; Hedges, R. E. M.

    2010-07-01

    Calcium isotopes in tissues are thought to be influenced by an individual's diet, reflecting parameters such as trophic level and dairy consumption, but this has not been carefully assessed. We report the calcium isotope ratios (δ 44/42Ca) of modern and archaeological animal and human bone ( n = 216). Modern sheep raised at the same location show 0.14 ± 0.08‰ higher δ 44/42Ca in females than in males, which we attribute to lactation by the ewes. In the archaeological bone samples the calcium isotope ratios of the herbivorous fauna vary by location. At a single site, the archaeological fauna do not show a trophic level effect. Humans have lower δ 44/42Ca than the mean site fauna by 0.22 ± 0.22‰, and the humans have a greater δ 44/42Ca range than the animals. No effect of sex or age on the calcium isotope ratios was found, and intra-individual skeletal δ 44/42Ca variability is negligible. We rule out dairy consumption as the main cause of the lower human δ 44/42Ca, based on results from sites pre-dating animal domestication and dairy availability, and suggest instead that individual physiology and calcium intake may be important in determining bone calcium isotope ratios.

  20. Oxygen isotopic ratios toward molecular clouds in the Galactic disk

    International Nuclear Information System (INIS)

    We present our observations of the J = 1 − 0 rotation transitions in molecular isotopes C18O and C17O toward a sample of molecular clouds with different galactocentric distances, using the Delingha 13.7m (DLH 13.7 m) telescope, administered by Purple Mountain Observatory, and its 9-beam SIS receiver. Complementary observations toward several sources with large galactocentric distance are obtained with the IRAM 30m and Mopra 22m telescopes. C18O/C17O abundance ratios reflecting the 18O/17O isotope ratios are obtained from integrated intensity ratios of C18O and C17O. We derived the ratio value for 13 sources covering a galactocentric distance range of 3kpc to 16kpc. In combination with our mapping results that provide a ratio value of 3.01±0.14 in the Galactic center region, it shows that the abundance ratio tends to increase with galactocentric distance, i.e., it supports a radial gradient along the Galactic disk for the abundance ratio. This is consistent with the inside-out formation scenario of our Galaxy. However, our results may suffer from small samples with large galactocentric distance. Combining our data with multi-transition lines of C18O and C17O will be helpful for constraining opacities and abundances and further confirming the Galactic radial gradient shown by the isotope ratio 18O/17O. (paper)

  1. Stable Isotope Ratio Measurement by NAA for Environmental Source Identification

    Energy Technology Data Exchange (ETDEWEB)

    Gone, Jeckong; Olmez, Ilhan; Ames, Michael R.

    1999-06-06

    The purpose of applying neutron activation analysis to the study of isotopic ratios is to examine whether ratios could be measured that are difficult to determine by other means and that could be used to distinguish between materials from different types of sources. The NAA is a sensitive analytical method for many elements that are typically present in levels too low to measure by other techniques, and because NAA is based on nuclear rather than chemical or physical reactions, the analytical signals from the two isotopes are readily distinguishable.

  2. Stable Isotope Ratio Measurement by NAA for Environmental Source Identification

    International Nuclear Information System (INIS)

    The purpose of applying neutron activation analysis to the study of isotopic ratios is to examine whether ratios could be measured that are difficult to determine by other means and that could be used to distinguish between materials from different types of sources. The NAA is a sensitive analytical method for many elements that are typically present in levels too low to measure by other techniques, and because NAA is based on nuclear rather than chemical or physical reactions, the analytical signals from the two isotopes are readily distinguishable

  3. Determining the isotopic ratio of 10B/11B

    International Nuclear Information System (INIS)

    The isotopic ratios can be very exactly determined by mass spectrometry. Using a mass spectrometer with an induction-coupled plasma as the excitation source (ICP-MS), radioactive contamination of the sample feeding system and the interface will result in very high blank readout. However, transforming the boron to the volatile boric acid trimethyl ester, the isotopic ratio can be measured with low blind value interference using a modified gas chromatographic mass spectrometer with thermal ionization (GC-MS). Space-charge effects also discussed in the paper have an influence on the accuracy of results, so that particular attention must be paid to calibration work. (orig./CB)

  4. Detection of adulterated honey produced by honeybee (Apis mellifera L.) colonies fed with different levels of commercial industrial sugar (C₃ and C₄ plants) syrups by the carbon isotope ratio analysis.

    Science.gov (United States)

    Guler, Ahmet; Kocaokutgen, Hasan; Garipoglu, Ali V; Onder, Hasan; Ekinci, Deniz; Biyik, Selim

    2014-07-15

    In the present study, one hundred pure and adulterated honey samples obtained from feeding honeybee colonies with different levels (5, 20 and 100 L/colony) of various commercial sugar syrups including High Fructose Corn Syrup 85 (HFCS-85), High Fructose Corn Syrup 55 (HFCS-55), Bee Feeding Syrup (BFS), Glucose Monohydrate Sugar (GMS) and Sucrose Sugar (SS) were evaluated in terms of the δ(13)C value of honey and its protein, difference between the δ(13)C value of protein and honey (Δδ(13)C), and C4% sugar ratio. Sugar type, sugar level and the sugar type*sugar level interaction were found to be significant (Psyrup level of all sugar types when the δ(13)C value of honey, Δδ(13)C (protein-honey), and C4% sugar ratio were used as criteria according to the AOAC standards. However, it was possible to detect the adulteration by using the same criteria in the honeys taken from the 20 and 100 L/colony of HFCS-85 and the 100L/colony of HFCS-55. Adulteration at low syrup level (20 L/colony) was more easily detected when the fructose content of HFCS syrup increased. As a result, the official methods (AOAC, 978.17, 1995; AOAC, 991.41, 1995; AOAC 998.12, 2005) and Internal Standard Carbon Isotope Ratio Analysis could not efficiently detect the indirect adulteration of honey obtained by feeding the bee colonies with the syrups produced from C3 plants such as sugar beet (Beta vulgaris) and wheat (Triticium vulgare). For this reason, it is strongly needed to develop novel methods and standards that can detect the presence and the level of indirect adulterations. PMID:24594168

  5. Carbon isotopic fractionation in heterotrophic microbial metabolism

    Science.gov (United States)

    Blair, N.; Leu, A.; Munoz, E.; Olsen, J.; Kwong, E.; Des Marais, D.

    1985-01-01

    Differences in the natural-abundance carbon stable isotopic compositions between products from aerobic cultures of Escherichia coli K-12 were measured. Respired CO2 was 3.4 percent depleted in C-13 relative to the glucose used as the carbon source, whereas the acetate was 12.3 percent enriched in C-13. The acetate C-13 enrichment was solely in the carboxyl group. Even though the total cellular carbon was only 0.6 percent depleted in C-13, intracellular components exhibited a significant isotopic heterogeneity. The protein and lipid fractions were -1.1 and -2.7 percent, respectively. Aspartic and glutamic acids were -1.6 and +2.7 percent, respectively, yet citrate was isotopically identical to the glucose. Probable sites of carbon isotopic fractionation include the enzyme, phosphotransacetylase, and the Krebs cycle.

  6. Homogeneous diet of contemporary Japanese inferred from stable isotope ratios of hair.

    Science.gov (United States)

    Kusaka, Soichiro; Ishimaru, Eriko; Hyodo, Fujio; Gakuhari, Takashi; Yoneda, Minoru; Yumoto, Takakazu; Tayasu, Ichiro

    2016-01-01

    The globalization of food production and distribution has homogenized human dietary patterns irrespective of geography, but it is uncertain how far this homogenization has progressed. This study investigated the carbon and nitrogen isotope ratios in the scalp hair of 1305 contemporary Japanese and found values of -19.4 ± 0.6‰ and 9.4 ± 0.6‰ (mean ± SD), respectively. Within Japan, the inter-regional differences for both isotope ratios was less than 1‰, which indicates low dietary heterogeneity among prefectural divisions. The carbon and nitrogen isotope ratios of the hair showed a significant correlation with the results of questionnaires on self-reported dietary habits. The carbon isotope ratios from Japan were lower than those in samples from the USA but higher than those in samples from Europe. These differences stem from the varying dietary proportions of food products originally derived from C3 and C4 plants. The dietary variation of Japan is as small as those of Europe and USA and smaller than those of some Asian countries. These results indicate that dietary homogeneity has progressed in Japan, which may indicate the influence from the spread of the Western-style diet and food globalization, although dietary heterogeneity among countries is still preserved. PMID:27616586

  7. A quantitative evaluation of spurious results in the infrared spectroscopic measurement of CO2 isotope ratios

    International Nuclear Information System (INIS)

    The possible generation of spurious results, arising from the application of infrared spectroscopic techniques to the measurement of carbon isotope ratios in breath, due to coincident absorption bands has been re-examined. An earlier investigation, which approached the problem qualitatively, fulfilled its aspirations in providing an unambiguous assurance that 13C16O2/12C16O2 ratios can be confidently measured for isotopic breath tests using instruments based on infrared absorption. Although this conclusion still stands, subsequent quantitative investigation has revealed an important exception that necessitates a strict adherence to sample collection protocol. The results show that concentrations and decay rates of the coincident breath trace compounds acetonitrile and carbon monoxide, found in the breath sample of a heavy smoker, can produce spurious results. Hence, findings from this investigation justify the concern that breath trace compounds present a risk to the accurate measurement of carbon isotope ratios in breath when using broadband, non-dispersive, ground state absorption infrared spectroscopy. It provides recommendations on the length of smoking abstention required to avoid generation of spurious results and also reaffirms, through quantitative argument, the validity of using infrared absorption spectroscopy to measure CO2 isotope ratios in breath. (author)

  8. Use of plutonium isotope activity ratios in dating recent sediments

    International Nuclear Information System (INIS)

    The majority of plutonium presently in the biosphere has come from the testing of nuclear devices. In the early 1950s, the Pu-238/239+240 activity ratio of fallout debris was > 0.04; in the more extensive test series of 1961 to 1962, the Pu-238/239+240 activity ratios were quite consistent at 0.02 to 0.03 and maximum fallout delivery occurred in mid-1963. A significant perturbation in Pu isotope activity ratios occurred in mid-1966 with the deposition of Pu-238 from the SNAP-9A reentry and burn-up. Recently deposited sediments have recorded these events and where accumulation rates are rapid (> 1 cm/y), changes in Pu isotope activity ratios can be used as a geochronological tool

  9. 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...... precision. Here, we present a new highly accurate and robust method for sample collection and subsequent simultaneous measurement of the dissolved gas ratios (N-2/Ar and O-2/Ar) and isotopic compositions (delta N-15(2) and delta O-18(2)) in seawater. The relatively simple sampling procedure using low cost...

  10. Stable isotope ratio (13C/12C mass spectrometry to evaluate carbon sources and sinks: changes and trends during the decomposition of vegetal debris from eucalyptus clone plantations (NW Spain

    Directory of Open Access Journals (Sweden)

    I. Fernandez

    2014-02-01

    Full Text Available Vegetal debris is known to participate in key soil processes such as the formation of soil organic matter (OM, also being a potential source of greenhouse gases to the atmosphere. However, its contribution to the isotopic composition of both the soil OM and the atmospheric carbon dioxide is not clear yet. Hence, the main objective of the present research is to understand the isotopic 13C changes and trends that take place during the successive biodegradative stages of decomposing soil organic inputs. By incubating bulk plant tissues for several months under laboratory controlled conditions, the kinetics of the CO2 releases and shifts in the 13C natural abundance of the solid residues were investigated using litter samples coming from forest plantations with a different clone (Anselmo: 1st clonal generation attained by morphological selection and Odiel: 2nd clonal generation genetically obtained of Eucalyptus globulus Labill. developed over granitic or schistic bedrocks and located in northwestern Spain. Significant isotopic variations with time were observed, probably due to the isotopically heterogeneous composition of these complex substrates in conjunction with the initial selective consumption of more easily degradable 13C-differentiated compounds during the first stages of the biodegradation, while less available or recalcitrant litter components were decomposed at later stages of biodegradation, generating products that have their own specific isotopic signatures. These results, which significantly differ depending on the type of clone, suggest that caution must be exercised when interpreting carbon isotope studies (at natural abundance levels since perturbations associated with the quality or chemical composition of the organic debris from different terrestrial ecosystems can have an important effect on the carbon stable isotope dynamics.

  11. Isotopic composition of carbon monoxide in St. Louis, Missouri area

    International Nuclear Information System (INIS)

    The concentration and isotropic composition of carbon monoxide were determined for air samples taken in the vicinity of St. Louis, Missouri, to provide information as to the movement of the pollutant plume from the city. Urban air was detected as far as 48 miles downwind of St. Louis; however, movement of the pollutant plume was not detected. The effect of engine carbon monoxide produced along a highway in a rural area was found to be minimal three miles downwind of the highway. Diurnal studies demonstrated an inverse relationship between carbon monoxide concentration and oxygen and carbon isotopic ratios during the night. A parallel relation prevailed during the day

  12. Uranium isotope ratio measurements using diode laser optogalvanic spectroscopy

    International Nuclear Information System (INIS)

    Conventional methods for measuring isotope ratios are seldom amenable to field use. In particular, thermal ionization mass spectrometry, while a very accurate and precise technique for measuring isotope ratios, requires instrumentation that is typically too cumbersome for field use. As an alternative to the use of conventional mass spectrometers, the authors have been pursuing glow discharge atomization coupled with high resolution optogalvanic spectroscopy (OGS) for quantification of uranium isotope ratios. This approach has been considered by others, but the authors have focussed on demountable discharge cells for practical ratio measurements. Further, the authors wish to make use of diode lasers for excitation. A field instrument does not require the accuracy and precision of a laboratory mass spectrometer, but must be sensitive to changes in sample isotopic composition, be free from interferences, and have sufficient precision for a decision to be made about the fate of the field sample; i.e., does the sample warrant further laboratory analysis? The technique ideally should require a minimum of sample preparation, and should at the same time be amenable to a variety of sample types. The glow discharge meets these requirements

  13. Isotope Ratios Reveal Trickery in the Produce Aisle

    Science.gov (United States)

    Journal of Chemical Education, 2007

    2007-01-01

    A new technique for the proper checking and banning of organic food items is proposed. The analysis of the nitrogen isotope ratio present in the food is found to be a perfect standard for the organic checking of the food products.

  14. Small Scale Variations in Carbon Oxygen Ratio

    International Nuclear Information System (INIS)

    The aim of the research reported here is the development of a methodology for the measurement of small scale variations in chemical elements concentrations, in particular of carbon - oxygen ratio. Knowledge of the C/O ratio is of importance to many problems in various fields. Here we single out the application in obtaining important information about the oil fields. The most fundamental reservoir parameters - oil, gas and water content - are critical factors in determining how each oil field should be developed. It is well established that carbon to oxygen ratio log yields accurate and repeatable data that can be used to identify and monitor reserves depletion. Recent improvements in neutron generator and gamma detector technologies resulted in small devices which allowed through-tubing measurements. Although the ratio of carbon and oxygen yields is a measure of the amount of oil around the tool it should be realized that a carbon signal can originate from several sources including the borehole, the cement behind the casing, the formation rock and the formation fluid. In order to evaluate these contributions individually we are proposing the modification of the neutron generator by insertion of segmented associated alpha particle detector. From the measurement of time of flight spectra (alpha particle detector - start signal; gamma ray detector - stop signal) it would be possible to determine the location of gamma ray producing voxel and in such a way to determine radial variations in several chemical elements concentrations, in particular of carbon to oxygen ratio. (authors)

  15. Exotic structure of carbon isotopes

    International Nuclear Information System (INIS)

    Ground state properties of C isotopes, deformation and electromagnetic moments, as well as electric dipole transition strength are investigated. We first study the ground state properties of C isotopes using a deformed Hartree-Fock (HF) + BCS model with Skyrme interactions. Isotope dependence of the deformation properties is investigated. Shallow deformation minima are found in several neutron-rich C isotopes. It is also shown that the deformation minima appear in both the oblate and the prolate sides in 17C and 19C having almost the same binding energies. Next, we carry out shell model calculations to study electromagnetic moments and electric dipole transitions of C isotopes. We point out the clear configuration dependence of the quadrupole and magnetic moments in the odd C isotopes, which will be useful to find out the deformation and spin-parties of the ground states of these nuclei. Electric dipole states of C isotopes are studied focusing on the interplay between low energy Pigmy strength and giant dipole resonances. Low peak energies, two-peak structure and large widths of the giant resonances show deformation effects. Calculated transition strength below dipole giant resonance in heavier C isotopes than 15C is found to exhaust 12∼15% of the Thomas-Reiche-Kuhn sum rule value and 50∼ 80% of the cluster sum rule value. (author)

  16. Carbon isotope analysis of fossil bone apatite

    International Nuclear Information System (INIS)

    The feasibility of using bone apatite for stable carbon isotope analysis of ancient bone for palaeodietary studies has been the subject of much controversy, and attempts to determine whether isotopic signatures are stable over time have produced contradictory results. We have tested this stability by measuring the δ13C values of chemically treated bone or tooth mineral of herbivores of known diet (browsers), in a temporal series. The results indicate that diagenesis of biogenic carbonates in the mineral over time is unexpectedly limited, and that chemical pretreatment further reduces diagenetic alteration of the biogenic signal. Enough biogenic carbonate remains to distinguish clearly between browsers and grazers, even after 3 million years

  17. Stable carbon isotope biogeochemistry of lakes along a trophic gradient

    Science.gov (United States)

    de Kluijver, A.; Schoon, P. L.; Downing, J. A.; Schouten, S.; Middelburg, J. J.

    2014-11-01

    The stable carbon (C) isotope variability of dissolved inorganic and organic C (DIC and DOC), particulate organic carbon (POC), glucose and polar-lipid derived fatty acids (PLFAs) was studied in a survey of 22 North American oligotrophic to eutrophic lakes. The δ13C of different PLFAs were used as proxy for phytoplankton producers and bacterial consumers. Lake pCO2 was primarily determined by autochthonous production (phytoplankton biomass), especially in eutrophic lakes, and governed the δ13C of DIC. All organic-carbon pools showed overall higher isotopic variability in eutrophic lakes (n = 11) compared to oligo-mesotrophic lakes (n = 11) because of the high variability in δ13C at the base of the food web (both autochthonous and allochthonous carbon). Phytoplankton δ13C was negatively related to lake pCO2 over all lakes and positively related to phytoplankton biomass in eutrophic lakes, which was also reflected in a large range in photosynthetic isotope fractionation (ϵCO2-phyto, 8-25‰). The carbon isotope ratio of allochthonous carbon in oligo-mesotrophic lakes was rather constant, while it varied in eutrophic lakes because of maize cultivation in the watershed.

  18. Carbonate clumped isotope thermometry in continental tectonics

    Science.gov (United States)

    Huntington, Katharine W.; Lechler, Alex R.

    2015-04-01

    Reconstructing the thermal history of minerals and fluids in continental environments is a cornerstone of tectonics research. Paleotemperature constraints from carbonate clumped isotope thermometry have provided important tests of geodynamic, structural, topographic and basin evolution models. The thermometer is based on the 13C-18O bond ordering in carbonates (mass-47 anomaly, Δ47) and provides estimates of the carbonate formation temperature independent of the δ18O value of the water from which the carbonate grew; Δ47 is measured simultaneously with conventional measurements of carbonate δ13C and δ18O values, which together constrain the isotopic composition of the parent water. Depending on the geologic setting of carbonate growth, this information can help constrain paleoenvironmental conditions or basin temperatures and fluid sources. This review examines how clumped isotope thermometry can shed new light on problems in continental tectonics, focusing on paleoaltimetry, basin evolution and structural diagenesis applications. Paleoaltimetry is inherently difficult, and the precision in carbonate growth temperature estimates is at the limit of what is useful for quantitative paleoelevation reconstruction. Nevertheless, clumped isotope analyses have enabled workers to address previously intractable problems and in many settings offer the best chance of understanding topographic change from the geologic record. The portion of the shallow crust residing at temperatures up to ca. 200 °C is important as host to economic resources and records of tectonics and climate, and clumped isotope thermometry is one of the few proxies that can access this critical range with sensitivity to temperature alone. Only a handful of studies to date have used clumped isotopes to investigate diagenesis and other sub-surface processes using carbonate crystallization temperatures or the sensitivity of Δ47 values to a sample's thermal history. However, the thermometer is

  19. NUSIMEP-7: uranium isotope amount ratios in uranium particles

    International Nuclear Information System (INIS)

    The Institute for Reference Materials and Measurements (IRMM) has extensive experience in the development of isotopic reference materials and the organization of interlaboratory comparisons (ILC) for nuclear measurements in compliance with the respective international guidelines (ISO Guide 34:2009 and ISO/IEC 17043:2010). The IRMM Nuclear Signatures Interlaboratory Measurement Evaluation Program (NUSIMEP) is an external quality control program with the objective of providing materials for measurements of trace amounts of nuclear materials in environmental matrices. Measurements of the isotopic ratios of the elements uranium and plutonium in small amounts, typical of those found in environmental samples, are required for nuclear safeguards and security, for the control of environmental contamination and for the detection of nuclear proliferation. The measurement results of participants in NUSIMEP are evaluated according to international guidelines in comparison to independent external certified reference values with demonstrated metrological traceability and uncertainty. NUSIMEP-7 focused on measurements of uranium isotope amount ratios in uranium particles aiming to support European Safeguards Directorate General for Energy (DG ENER), the International Atomic Energy Agency's (IAEA) network of analytical laboratories for environmental sampling (NWAL) and laboratories in the field of particle analysis. Each participant was provided two certified test samples: one with single and one with double isotopic enrichment. These NUSIMEP test samples were prepared by controlled hydrolysis of certified uranium hexafluoride in a specially designed aerosol deposition chamber at IRMM. Laboratories participating in NUSIMEP-7 received the test samples of uranium particles on two graphite disks with undisclosed isotopic ratio values n(234U)/n(238U), n(235U)/n(238U) and n(236U)/n(238U). The uranium isotope ratios had to be measured using their routine analytical procedures

  20. Applications of stable Isotope ratios determinations in fruit juice authentication

    International Nuclear Information System (INIS)

    Full text: Adulteration of a product consists in making it impure by fraudulent addition of a foreign or inferior substance. The result is either an alteration of the product and of its quality or a falsification. The falsification is a voluntary act with the intention of abuse. The falsification may be more or less sophisticated and its sophistication as well as its costs increases with the improvement of analytical methods. Vacuum concentration with aroma does not affect the chemical composition of fruit juices and therefore the determination of deuterium (D) and oxygen-18 content in waters is the most confident procedure for differentiating between a natural single strength juice and a juice rediluted from a concentrate. This technique is based on the fact that when absorbed by a plant, the rainwater or the irrigation water is fractionated by evapotranspiration, and enriched in the heavy isotopes (deuterium and oxygen-18) with respect to the light isotope (hydrogen and oxygen-16, respectively). It is known that climatic conditions affect the isotope content of rain waters and therefore that of fruit juices waters: the warmer climate, the higher the deuterium and oxygen-18 contents in water. Rainwater and tap water have nearly the same isotopic content and the water of fruit juices derived from concentrate by dilution with tap water has an isotopic content close to that of tap water. This makes it easy to distinguish diluted concentrates from the isotopically more enriched water of authentic single strength juice. In this study, single strength juice, in Romanian fruits, were investigated by mean of stable isotope measurements (oxygen, hydrogen and carbon) in order to offer a discussion basis for the authenticity of some fruit juices currently available on Romanian market. (authors)

  1. Finite mixture models for the computation of isotope ratios in mixed isotopic samples

    Science.gov (United States)

    Koffler, Daniel; Laaha, Gregor; Leisch, Friedrich; Kappel, Stefanie; Prohaska, Thomas

    2013-04-01

    Finite mixture models have been used for more than 100 years, but have seen a real boost in popularity over the last two decades due to the tremendous increase in available computing power. The areas of application of mixture models range from biology and medicine to physics, economics and marketing. These models can be applied to data where observations originate from various groups and where group affiliations are not known, as is the case for multiple isotope ratios present in mixed isotopic samples. Recently, the potential of finite mixture models for the computation of 235U/238U isotope ratios from transient signals measured in individual (sub-)µm-sized particles by laser ablation - multi-collector - inductively coupled plasma mass spectrometry (LA-MC-ICPMS) was demonstrated by Kappel et al. [1]. The particles, which were deposited on the same substrate, were certified with respect to their isotopic compositions. Here, we focus on the statistical model and its application to isotope data in ecogeochemistry. Commonly applied evaluation approaches for mixed isotopic samples are time-consuming and are dependent on the judgement of the analyst. Thus, isotopic compositions may be overlooked due to the presence of more dominant constituents. Evaluation using finite mixture models can be accomplished unsupervised and automatically. The models try to fit several linear models (regression lines) to subgroups of data taking the respective slope as estimation for the isotope ratio. The finite mixture models are parameterised by: • The number of different ratios. • Number of points belonging to each ratio-group. • The ratios (i.e. slopes) of each group. Fitting of the parameters is done by maximising the log-likelihood function using an iterative expectation-maximisation (EM) algorithm. In each iteration step, groups of size smaller than a control parameter are dropped; thereby the number of different ratios is determined. The analyst only influences some control

  2. Stable carbon isotope analysis of nucleic acids to trace sources of dissolved substrates used by estuarine bacteria.

    OpenAIRE

    Coffin, R B; Velinsky, D J; R. Devereux; Price, W A; Cifuentes, L A

    1990-01-01

    The natural abundance of stable carbon isotopes measured in bacterial nucleic acids extracted from estuarine bacterial concentrates was used to trace sources of organic matter for bacteria in aquatic environments. The stable carbon isotope ratios of Pseudomonas aeruginosa and nucleic acids extracted from cultures resembled those of the carbon source on which bacteria were grown. The carbon isotope discrimination between the substrate and total cell carbon from bacterial cultures averaged 2.3%...

  3. Magnesium Isotope Ratios in omega Centauri Red Giants

    CERN Document Server

    Da Costa, G S; Yong, David

    2013-01-01

    We have used high resolution observations obtained at the AAT with UHRF (R ~ 100,000) and at Gemini-S with b-HROS (R ~ 150,000) to determine magnesium isotope ratios for seven omega Centauri red giants that cover a range in iron abundance from [Fe/H] = --1.78 to --0.78 dex, and for two red giants in M4 (NGC 6121). The omega Centauri stars sample both the "primordial" (i.e., O-rich, Na and Al-poor) and the "extreme" (O-depleted, Na and Al-rich) populations in the cluster. The primordial population stars in both omega Centauri and M4 show (25Mg, 26Mg)/24 Mg isotopic ratios that are consistent with those found for the primordial population in other globular clusters with similar [Fe/H] values. The isotopic ratios for the omega Centauri extreme stars are also consistent with those for extreme population stars in other clusters. The results for the extreme population stars studied indicate that the 26Mg/24Mg ratio is highest at intermediate metallicities ([Fe/H] < --1.4 dex), and for the highest [Al/Fe] values....

  4. The first protocol of stable isotope ratio assessment in tumor tissues based on original research.

    Science.gov (United States)

    Taran, Katarzyna; Frączek, Toma; Kamiński, Rafal; Sitkiewicz, Anna; Kobos, Jozef; Paneth, Piotr

    2015-09-01

    Thanks to proteomics and metabolomics, for the past several years there has been a real explosion of information on the biology of cancer, which has been achieved by spectroscopic methods, including mass spectrometry. These modern techniques can provide answers to key questions about tissue structure and mechanisms of its pathological changes. However, despite the thousands of spectroscopic studies in medicine, there is no consensus on issues ranging from the choice of research tools, acquisition and preparation of test material to the interpretation and validation of the results, which greatly reduces the possibility of transforming the achieved knowledge to progress in the treatment of individual patients. The aim of this study was to verify the utility of isotope ratio mass spectrometry in the evaluation of tumor tissues. Based on experimentation on animal tissues and human neoplasms, the first protocol of stable isotope ratio assessment of carbon and nitrogen isotopes in tumor tissues was established. PMID:26619108

  5. Carbon isotope anomalies in carbonates of the Karelian series

    Science.gov (United States)

    Iudovich, Ia. E.; Makarikhin, V. V.; Medvedev, P. V.; Sukhanov, N. V.

    1990-07-01

    Results are presented on carbon isotope distributions in carbonates of the Karelian complex. A highly anomalous isotopic composition was found in carbonate rocks aged from 2.6 to 1.9 b.y. In the stromatolitic carbonates of the Onega water table, delta-(C-13) reaches a value of +18 percent, while the shungite layer of the Zaonega horizon is characterized by a wide dispersion (from +7.9 to -11.8 percent). These data are in good agreement with the known geochemical boundary (about 2.2 b.y. ago) in the history of the earth.

  6. High precision isotopic ratio analysis of volatile metal chelates

    International Nuclear Information System (INIS)

    High precision isotope ratio measurements have been made for a series of volatile alkaline earth and transition metal chelates using conventional GC/MS instrumentation. Electron ionization was used for alkaline earth chelates, whereas isobutane chemical ionization was used for transition metal studies. Natural isotopic abundances were determined for a series of Mg, Ca, Cr, Fe, Ni, Cu, Cd, and Zn chelates. Absolute accuracy ranged between 0.01 and 1.19 at. %. Absolute precision ranged between +-0.01-0.27 at. % (RSD +- 0.07-10.26%) for elements that contained as many as eight natural isotopes. Calibration curves were prepared using natural abundance metals and their enriched 50Cr, 60Ni, and 65Cu isotopes covering the range 0.1-1010.7 at. % excess. A separate multiple isotope calibration curve was similarly prepared using enriched 60Ni (0.02-2.15 at. % excess) and 62Ni (0.23-18.5 at. % excess). The samples were analyzed by GC/CI/MS. Human plasma, containing enriched 26Mg and 44Ca, was analyzed by EI/MS. 1 figure, 5 tables

  7. Zinc Isotope Ratios as Indicators of Diet and Trophic Level in Arctic Marine Mammals.

    Directory of Open Access Journals (Sweden)

    Klervia Jaouen

    Full Text Available Carbon and nitrogen stable isotope ratios of bone collagen are an established method for dietary reconstruction, but this method is limited by the protein preservation. Zinc (Zn is found in bioapatite and the isotopic compositions of this element constitute a very promising dietary indicator. The extent of fractionation of Zn isotopes in marine environments, however, remains unknown. We report here on the measurement of zinc, carbon and nitrogen isotopes in 47 marine mammals from the archaeological site of Arvik in the Canadian Arctic. We undertook this study to test and demonstrate the utility of Zn isotopes in recent mammal bone minerals as a dietary indicator by comparing them to other isotopic dietary tracers. We found a correlation between δ66Zn values and trophic level for most species, with the exception of walruses, which may be caused by their large seasonal movements. δ6Zn values can therefore be used as a dietary indicator in marine ecosystems for both modern and recent mammals.

  8. Zinc Isotope Ratios as Indicators of Diet and Trophic Level in Arctic Marine Mammals.

    Science.gov (United States)

    Jaouen, Klervia; Szpak, Paul; Richards, Michael P

    2016-01-01

    Carbon and nitrogen stable isotope ratios of bone collagen are an established method for dietary reconstruction, but this method is limited by the protein preservation. Zinc (Zn) is found in bioapatite and the isotopic compositions of this element constitute a very promising dietary indicator. The extent of fractionation of Zn isotopes in marine environments, however, remains unknown. We report here on the measurement of zinc, carbon and nitrogen isotopes in 47 marine mammals from the archaeological site of Arvik in the Canadian Arctic. We undertook this study to test and demonstrate the utility of Zn isotopes in recent mammal bone minerals as a dietary indicator by comparing them to other isotopic dietary tracers. We found a correlation between δ66Zn values and trophic level for most species, with the exception of walruses, which may be caused by their large seasonal movements. δ6Zn values can therefore be used as a dietary indicator in marine ecosystems for both modern and recent mammals. PMID:27010907

  9. Development and application of liquid chromatography coupled to isotope ratio mass spectrometry

    International Nuclear Information System (INIS)

    Stable isotope analysis has found widespread applications in various disciplines such as archaeology, geochemistry, biology, food authenticity, and forensic science. Coupling chromatography to isotope ratio mass spectrometry for compound-specific isotope analysis (CSIA) is a trend, as it provides several advantages over bulk isotope analysis, e.g., relatively simple sample preparation, the ability to measure individual compounds in a complex mixture in one run, and the reduced sample size required for precise isotope analysis. Gas chromatography coupled to isotope ratio mass spectrometry (GC/IRMS) has been well-established for compound-specific isotope analysis of volatile organic compounds within the last two decades. However, an interface combining liquid chromatography with isotope ratio mass spectrometry (LC/IRMS) was not commercially available until 2004. The current design of the interface requires using a carbon-free eluent in chromatographic separation. This requirement limits the application of the most frequently used reversed-phase liquid chromatography in CSIA, because the elution strength of water at room temperature is too low to serve as mobile phase in reversed-phase separations. In order to increase the elution strength of water, we propose using high temperature water for chromatographic elution. The polarity of water decreases with an increase of temperature, yielding increased elution strength in reversed-phase columns. Therefore, high temperature water can be used as eluent instead of organic solvent for combining reversed-phase liquid chromatography with isotope ratio mass spectrometry (RPLC/IRMS). Additionally, temperature gradients can replace organic solvent gradients to increase chromatographic resolution. This is very important for LC/IRMS analysis, as precise isotope analysis requires baseline separation of analytes. In this thesis, high-temperature reversed-phase liquid chromatography was coupled to, and for the first time carefully

  10. Development and application of liquid chromatography coupled to isotope ratio mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lijun

    2014-02-19

    Stable isotope analysis has found widespread applications in various disciplines such as archaeology, geochemistry, biology, food authenticity, and forensic science. Coupling chromatography to isotope ratio mass spectrometry for compound-specific isotope analysis (CSIA) is a trend, as it provides several advantages over bulk isotope analysis, e.g., relatively simple sample preparation, the ability to measure individual compounds in a complex mixture in one run, and the reduced sample size required for precise isotope analysis. Gas chromatography coupled to isotope ratio mass spectrometry (GC/IRMS) has been well-established for compound-specific isotope analysis of volatile organic compounds within the last two decades. However, an interface combining liquid chromatography with isotope ratio mass spectrometry (LC/IRMS) was not commercially available until 2004. The current design of the interface requires using a carbon-free eluent in chromatographic separation. This requirement limits the application of the most frequently used reversed-phase liquid chromatography in CSIA, because the elution strength of water at room temperature is too low to serve as mobile phase in reversed-phase separations. In order to increase the elution strength of water, we propose using high temperature water for chromatographic elution. The polarity of water decreases with an increase of temperature, yielding increased elution strength in reversed-phase columns. Therefore, high temperature water can be used as eluent instead of organic solvent for combining reversed-phase liquid chromatography with isotope ratio mass spectrometry (RPLC/IRMS). Additionally, temperature gradients can replace organic solvent gradients to increase chromatographic resolution. This is very important for LC/IRMS analysis, as precise isotope analysis requires baseline separation of analytes. In this thesis, high-temperature reversed-phase liquid chromatography was coupled to, and for the first time carefully

  11. Measurement of carbon-13:carbon-12 ratios by Fourier transform infrared spectrometry

    International Nuclear Information System (INIS)

    An approach to the measurement of 13C:12C ratios in isotopically enriched samples is described. The carbon in samples is converted into CO2 gas by either combustion of organic material or acidification of carbonate. The gas is then measured by FTIR spectrometry. When spectra are recorded at 0.25 cm-1 resolution the magnitude of the isotopic shift is such that the areas of 12C and 13C rotational lines of the ν3 vibrational band for CO2 can be measured and the isotopic composition determined by reference to a standard calibration graph. The relative standard deviation at natural abundance is 1.2%, which gives an absolute limit of detection of 0.026 atom-% 13C. Details of the decomposition procedures and a comparison of the results with those obtained by mass spectrometry are also presented. (author)

  12. Development of a new TIMS for boron isotopic ratio analysis

    International Nuclear Information System (INIS)

    Thermal Ionization Mass Spectrometry is the widely used technique for precise isotopic ratio measurements of materials of interest in the fields of nuclear technology and geochronology. The basic evaluation of the instrument shows that the instrument is suitable for precise isotopic ratio measurements for Boron. It can be used for other masses falling in the mass range of 1-200 amu. The sensitivity and precision obtained are highly satisfactory for the analysis of Boron samples. Analysis time involved in measurement on one sample is 30-35 minutes. Moreover, the provision of turret with 12 filament assemblies increases the throughput of the system and makes it more useful for the plant where the operator has to routinely analyse more number of samples

  13. Predicting the isotopic ratio of western European Precipitation using an isotope trajectory model

    International Nuclear Information System (INIS)

    Full text: Spatial and seasonal variations of isotopic ratios in precipitation across Western Europe are well documented. Locations of moisture uptake, transport pathways, condensation temperatures, and surface temperatures at source region and precipitation location all influence the water isotope cycle. Isotope cycle modelling has been included in Global Circulation Models (GCMs) in order to model all of the controlling factors. However, the relative importance of each of these processes remains unclear due to the difficulties in decoupling these processes in GCMs. A combination of a Lagrangian Particle Dispersion Model and an extended Rayleigh distillation theory model allows the effects of different atmospheric processes on isotopic fractionation to be investigated. This method has previously been used to model precipitation in Antarctica and Greenland with excellent results. However, there are added complications involved when modelling rainfall rather than snowfall, such as isotopic re-equilibration between falling raindrops and the surrounding water vapour. Lower latitude locations also experience more evaporation and re-evaporation along the path of a moist air parcel, increasing opportunities for fractionation. These models have been used to predict the hydrogen and oxygen isotope ratios of rainfall in the U.K and Ireland. The model results have been compared with measured isotopic data from daily rainfall samples in order to test how the modelled processes interact. A case study is presented which incorporates observed data collected throughout November 2005 at stations in Norwich, Birmingham and Dublin, together with the corresponding temporal model predictions at these localities. (author)

  14. Nitrate pollution in groundwater: source identification using isotope ratio

    International Nuclear Information System (INIS)

    Isotope ratios for identification of pollutant source is an emerging scientific tool. An investigation was carried out to find out the origin of nitrate in groundwater in an area which receives pollutant of different origin like inorganic fertilizers, organic manures besides urban wastes. The δ15N values of nitrate clearly indicated the possibility of groundwater pollution by nitrate originating from human and animal wastes. (author)

  15. Exotic Structure of Carbon Isotopes

    CERN Document Server

    Suzuki, T; Hagino, K; Suzuki, Toshio; Sagawa, Hiroyuki; Hagino, Kouichi

    2002-01-01

    We studied firstly the ground state properties of C-isotopes using a deformed Hartree-Fock (HF)+ BCS model with Skyrme interactions. Shallow deformation minima are found in several neutron$-$rich C-isotopes. It is shown also that the deformation minima appear in both the oblate and the prolate sides in $^{17}$C and $^{19}$C having almost the same binding energies. Secondly, we carried out shell model calculations to study electromagnetic moments and electric dipole transitions of the C-isotopes. We point out the clear configuration dependence of the quadrupole and magnetic moments in the odd C-isotopes, which will be useful to find out the deformations and the spin-parities of the ground states of these nuclei. We studied electric dipole states of C-isotopes focusing on the interplay between low energy Pigmy strength and giant dipole resonances. Reasonable agreement is obtained with available experimental data for the photoreaction cross sections both in the low energy region below $\\hbar \\omega $=14 MeV and ...

  16. Carbon and Carbon Isotope Cycling in the Western Canadian Arctic

    Science.gov (United States)

    Mol, Jacoba; Thomas, Helmuth

    2016-04-01

    Increasing carbon dioxide levels in the atmosphere are having drastic effects on the global oceans. The Arctic Ocean is particularly susceptible to change as warming, sea-ice loss and a weak buffering capacity all influence this complicated semi-enclosed sea. In order to investigate the inorganic carbon system in the Canadian Arctic, water samples were collected in the Beaufort Sea, on the Alaskan shelf, at the Mackenzie river delta, and in Amundsen Gulf during the summer of 2014 and were analyzed for dissolved inorganic carbon (DIC), total alkalinity (TA), DI13C and 18O isotopes. Carbon isotopes are used to investigate the role of biological production on the uptake and transfer of inorganic carbon to depth. A preferential uptake of the lighter 12C relative to the heavier 13C isotope during biological production leads to a fractionation of the 13C/12C isotopes in both the organic matter and the water column. This results in an enrichment of DI13C in the high productivity surface waters and a depletion of DI13C at depth. Physical processes including freshwater input, brine rejection, and water mass mixing are investigated through the measurement of oxygen isotopes. Differences in the carbon system across the study area due to both biological and physical processes are assessed using depth profiles of DI13C and related carbon system parameters.

  17. Carbon isotope separation by absorptive distillation

    International Nuclear Information System (INIS)

    The feasibility of separating carbon isotopes by absorptive distillation has been studied for CO absorption by cryogenic solvents. Phase equilibrium, isotopic separation, and mass transfer data were taken between 77.4 and 114.3 K for the following solvents: propane, propylene, 1:1 propane-propylene, 1-butene, isobutane and nitrogen. Carbon monoxide solubility followed Henry's Law, with a maximum experimental solubility of 6.5 mole percent. Isotopic separation between CO in the gas and liquid phases using hydrocarbon solvents was several times that for pure CO vapor-liquid equilibrium. The maximum observed isotopic separation factor was 1.029 at 77.4 K with the propane-propylene solvent mixture. Mass transfer measurements yielded calculated HETP's of 2 to 5 cm for a possible separation system. An attempt has been made to correlate isotopic separation data using Hildebrand's theory of solutions. The differential absorption of isotopic CO species is expressed as a difference in solubility of the isotopic CO molecules. Data for propane, propylene, and 1-butene show approximately the same behavior at varying temperatures

  18. Carbon isotope separation by absorptive distillation

    International Nuclear Information System (INIS)

    The feasibility of separating carbon isotopes by absorptive distillation has been studied for CO absorption by cryogenic solvents. Phase equilibrium, isotopic separation, and mass transfer data were taken between 77.4 and 114.3 K for the following solvents: propane, propylene, 1:1 propane-propylene, 1-butene, isobutane and nitrogen. Carbon monoxide solubility followed Henry's Law, with a maximum experimental solubility of 6.5 mole per cent. Isotopic separation between CO in the gas and liquid phases using hydrocarbon solvents was several times that for pure CO vapor-liquid equilibrium. The maximum observed isotopic separation factor was 1.029 at 77.4 K with the propane-propylene solvent mixture. Mass transfer measurements yielded calculated HTU's of 2 to 5 cm for a possible separation system. An attempt has been made to correlate isotopic separation data using Hildebrand's theory of solutions. The differential absorption of isotopic CO species is expressed as a difference in solubility of the isotopic CO molecules. Data for propane, propylene, and 1-butene show approximately the same behavior at varying temperatures

  19. Carbon and oxygen isotope separation by plasma chemical reactions in carbon monoxide glow discharge

    International Nuclear Information System (INIS)

    The separation of carbon and oxygen isotopes in CO glow discharge has been studied. The isotope enrichment in the products was measured by quadru-pole mass spectrometer. The reaction yield and empirical formula of solid phase products were determined by the gas-volumetric analysis. The stable products obtained in our experiment are CO2 and solid polymers formed on the discharge wall. The polymer consists of both carbon and oxygen and the oxygen/carbon mole ratio in the polymer is 0.35±0.05. Thi isotope enrichment coefficients show a strong negative dependence on discharge current though the relative reaction yields have an opposite tendency. Consequently, the maximum isotope enrichment coefficients for 13C in wall deposit of 2.31 and for 18O in CO2 of 1.37 are obtained when the discharge current and the reaction yields are minimum in our experimental range. The experimental results of isotope enrichment have been compared with theoretical values estimated by an analytical model of literature. The dilution mechanism of the isotope enrichment of stable products is inferred from the isotopic distributions of 13C and 18O in products and theoretical predictions for isotope enrichment. (author)

  20. Ratio of the dose factors of the isotopes of iodine

    International Nuclear Information System (INIS)

    The ratio of dose factors occurring during inhalation and ingestion to the respective dose factors of I-129 is calculated for the isotopes of I-123 to I-126 and I-129 to I-135. All the dose factors refer to the thyroid as the critical organ. A distinction is made between adults and infants up to 1 year of age. To calculate the ratios only the effective energies and the effective half-lives in the human body and on grass are required. Most of the data have been taken from the literature. The effective energies of I-123 and I-125 have been calculated as examples. (orig.)

  1. Isotopic enrichment of diamond using microwave plasma-assisted chemical vapor deposition with high carbon conversion efficiency

    International Nuclear Information System (INIS)

    Isotopically-controlled diamond crystals were grown using microwave plasma-assisted chemical vapor deposition. First, the highest carbon isotopic enrichment and their controllability were examined. Although the highest 12C isotopic ratio of 99.998% was achieved using methane with an isotopic ratio of 99.999%, the memory effect of an unintended carbon isotope was found to be considerable when the carbon isotopic ratio of feeding methane was tuned for isotopic multilayer formation. Secondly, a unique gas feeding sequence was proposed for increasing the carbon conversion efficiency from methane to diamond. Increasing the conversion efficiency is done by finding a suitable balance between the methane feeding rate and the carbon consumption rate for diamond growth. A high conversion efficiency of 70% was obtained for a polycrystalline diamond with a high 12C isotopic ratio of 99.997%. - Highlights: • Isotopic control of diamond films was investigated. • A high microwave power density condition was applied for diamond growth. • The controllable range of the carbon isotopic ratio was demonstrated. • Diamond films having the highest 12C carbon isotopic enrichment were grown. • High carbon conversion efficiency of 70% was achieved

  2. Isotopic Hg in an Allende carbon-rich residue

    Science.gov (United States)

    Reed, G. W., Jr.; Jovanovic, S.

    1990-01-01

    A carbon-rich residue from Allende subjected to stepwise heating yielded two isotopically resolvable types of Hg: one with an (Hg-196)/(Hg-202) concentration ratio the same as terrestrial (monitor) Hg; the other enriched in Hg-196 relative to Hg-202 by about 60 percent. Hg with the 202 isotope enriched relative to 196, as is found in bulk Allende, was not observed. Whether the result of mass fractionation or nucleosynthesis, the distinct types of Hg entered different carrier phases and were not thermally mobilized since the accretion of the Allende parent body.

  3. New laser spectroscopic technique for stable-isotope ratio analysis

    International Nuclear Information System (INIS)

    A new approach to stable-isotope ratio analysis based on atomic hyperfine structure is demonstrated. This laser spectroscopic scheme is virtually interference-free. A minor constituent in a complex matrix can be selectively analyzed without extensive sample preparation. A single-frequency tunable cw ring dye laser is used as the excitation source and a demountable cathode discharge is used as the atomizer and detector. Samples are electrodeposited on the demountable cathode and hyperfine profiles are collected by optogalvanic detection. By spectral deconvolution, the relative abundances of all isotopes present can be determined with good accuracy and precision. The technique is demonstrated for copper contents as low as 1.6 ppM, using the atomic hyperfine structure of Cu I 578.2 nm non-resonance transition. It is also successfully tested for analysis of copper isotopes in human blood. The sensitivity of doppler-free polarization spectroscopy in atomic flames is showed to be competitive with other sensitive laser techniques such as the fluorescence spectrometric methods. Improved detectability of polarization rotation and excellent suppression of flame background noise enable this method to achieve detection limits of parts per trillion levels of sodium and 37 ppB of barium. The spectral resolution is suitable for isotopic analysis, and the technique offers excellent selectivity and minimum spectral interference

  4. New laser spectroscopic technique for stable-isotope ratio analysis

    International Nuclear Information System (INIS)

    Reliable and safe application of isotopes as tracers is important in many areas, including biomedical, environmental and geochronological sciences. A new approach to stable-isotope ratio analysis based on atomic hyperfine structure is demonstrated. This laser spectroscopic scheme is virtually interference-free because of the highly selective and specific nature of hyperfine structures. Hence, a minor constituent in a complex matrix can be selectively analyzed without extensive sample preparation. A single-frequency tunable cw ring dye laser is used as the excitation source and a specially designed and constructed demountable cathode discharge is used as the atomizer and detector. Samples are electrodeposited on the demountable cathode and hyperfine profiles are collected by optogalvanic detection. By spectral deconvolution, the relative abundances of all isotopes present can be determined with good accuracy and precision. The technique is demonstrated for copper concentrations as low as 1.6 ppm, using the atomic hyperfine structure of CuI 578.2 nm non-resonance transition. It is also successfully tested for analysis of copper isotopes in human blood

  5. Total flash evaporation studies for uranium isotope ratio measurements

    International Nuclear Information System (INIS)

    Accurate isotopic ratio measurements on uranium samples are essential for nuclear material accounting, enrichment programs and for geochemical research applications. Thermal ionization mass spectrometry is widely followed for these measurements. Conventional measurement technique involving Faraday Cups demands larger samples and fractionation correction for the measured data when accurate data are required. Total evaporation or total flash evaporation technique (TFE) is reported to circumvent these difficulties. The technique consists of heating the sample to exhaustion while simultaneously acquiring intensities of all the isotopes at respective cups and then computing the isotope ratios from the summed up intensities. A brief account of literature on this technique is given in a recent paper. TFE studies were conducted by us on NBS -uranium standard solution (SRMU-010) and on a depleted uranium sample solution with an objective to explore the possibility of using a relatively small quantities in the range 300-350 ng, compared to 2 μg of uranium generally required for routine measurements using Faraday Cups. The methodology followed and the results obtained are presented in this paper

  6. Biomedical and Forensic Applications of Combined Catalytic Hydrogenation-Stable Isotope Ratio Analysis

    Directory of Open Access Journals (Sweden)

    Mark A. Sephton

    2007-01-01

    Full Text Available Studies of biological molecules such as fatty acids and the steroid hormones have the potential to benefit enormously from stable carbon isotope ratio measurements of individual molecules. In their natural form, however, the body’s molecules interact too readily with laboratory equipment designed to separate them for accurate measurements to be made.Some methods overcome this problem by adding carbon to the target molecule, but this can irreversibly overprint the carbon source ‘signal’. Hydropyrolysis is a newly-applied catalytic technique that delicately strips molecules of their functional groups but retains their carbon skeletons and stereochemistries intact, allowing precise determination of the carbon source. By solving analytical problems, the new technique is increasing the ability of scientists to pinpoint molecular indicators of disease, elucidate metabolic pathways and recognise administered substances in forensic investigations.

  7. Carbon isotopes as indicators of peatland growth?

    Science.gov (United States)

    Alewell, Christine; Krüger, Jan Paul; von Sengbusch, Pascal; Szidat, Sönke; Leifeld, Jens

    2016-04-01

    As undisturbed and/or growing peatlands store considerable amounts of carbon and are unique in their biodiversity and species assemblage, the knowledge of the current status of peatlands (growing with carbon sequestration, stagnating or degrading with carbon emissions) is crucial for landscape management and nature conservation. However, monitoring of peatland status requires long term measurements and is only feasible with expert knowledge. The latter determination is increasingly impeded in a scientific world, where taxonomic expert knowledge and funding of long term monitoring is rare. Stable carbon and nitrogen isotopes depth profiles in peatland soils have been shown to be a useful tool to monitor the degradation of peatlands due to permafrost thawing in Northern Sweden (Alewell et al., 2011; Krüger et al., 2014), drainage in Southern Finland (Krüger et al., 2016) as well as land use intensification in Northern Germany (Krüger et al., 2015). Here, we tackle the questions if we are able to differentiate between growing and degrading peats with the use of a combination of carbon stable (δ13C) and radiogenic isotope data (14C) with peat stratification information (degree of humification and macroscopic plant remains). Results indicate that isotope data are a useful tool to approximate peatland status, but that expert taxonomic knowledge will be needed for the final conclusion on peatland growth. Thus, isotope tools might be used for landscape screening to pin point sites for detailed taxonomic monitoring. As the method remains qualitative future research at these sites will need to integrate quantitative approaches to determine carbon loss or gain (soil C balances by ash content or C accumulation methods by radiocarbon data; Krüger et al., 2016). Alewell, C., R. Giesler, J. Klaminder, J. Leifeld, and M. Rollog. 2011. Stable carbon isotopes as indicators for micro-geomorphic changes in palsa peats. Biogeosciences, 8, 1769-1778. Krüger, J. P., Leifeld, J

  8. Stable strontium isotopic ratios from archaeological organic remains from the Thorsberg peat bog

    DEFF Research Database (Denmark)

    Nosch, Marie-Louise Bech; von Carnap-Bornheim, Claus; Grupe, Gisela;

    2007-01-01

    Pilot study analysing stable strontium isotopic ratios from Iron Age textile and leather finds from the Thorsberg peat bog.......Pilot study analysing stable strontium isotopic ratios from Iron Age textile and leather finds from the Thorsberg peat bog....

  9. Emerging Techniques in Vegetable Oil Analysis Using Stable Isotope Ratio Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, S. D.; Rhodes, C.

    2002-07-01

    As the practice of vegetable oil adulteration becomes more sophisticated, the possibility to subvert detection using established techniques such as capillary gas chromatography is increasing. One of the most powerful techniques to be used in food authenticity studies is stable isotope ratio mass spectrometry (SIRMS) which utilises differences in the natural abundance of the stable isotopes of the light bio elements hydrogen, nitrogen, carbon, oxygen and sulfur to detect food fraud. SIRMS has found application in the authentication of a wide range of foodstuffs, including fruit juices, wines, spirits, honey and to detect the adulteration of flavour compounds with synthetic analogues. This papers reviews the current state-of-the-art for the authentication of vegetable oils using SIRMS and highlights emergent techniques such as compound-an position specific-isotope mass spectrometry. These latter developments offer the potential to provide more rapid and improved detection of the economic adulteration of vegetable oils. (Author) 38 refs.

  10. Precise determination of stable chlorine isotopic ratios in low-concentration natural samples

    Science.gov (United States)

    Magenheim, A. J.; Spivack, A. J.; Volpe, C.; Ransom, B.

    1994-07-01

    Investigation of stable chlorine isotopes in geological materials has been hindered by large sample requirements and/or lack of analytical precision. Here we describe precise methods for the extraction, isolation, and isotopic analysis of low levels of chlorine in both silicate and aerosol samples. Our standard procedure uses 2 μg of Cl for each isotopic analysis. External reproducibility (1 σ) is 0.25%. for the 37Cl /35Cl measurements. Chlorine is extracted from silicate samples (typically containing at least 20 μg of Cl) via pyrohydrolysis using induction heating and water vapor as the carrier, and the volatilized chlorine is condensed in aqueous solution. Atmospheric aerosols collected on filters are simply dissolved in water. Prior to isotopic measurement, removal of high levels of SO 42-, F -, and organic compounds is necessary for the production of stable ion beams. Sulfate is removed by BaSCO 4 precipitation, F - by CaF 2 precipitation, and organic compounds are extracted with activated carbon. Chlorine is converted to stoichiometric CsCl by cation exchange, and isotopic ratios are determined by thermal ionization mass spectrometry of Cs 2Cl +. We demonstrate that the sensitivity and precision of this method allow resolution of natural variations in chlorine isotopic composition, and thereby provide insight to some fundamental aspects of chlorine geochemistry.

  11. The assesment of the food quality by 13 C isotope ratio mass spectrometry

    International Nuclear Information System (INIS)

    Carbon 13 analysis can be a key analytical technique used in the fight to detect undeclared addition of low cost adulterants to high value foods. The natural abundance of 13 C in food is related to how the plant fix the carbon during photosynthesis. Plants that use a C3 photosynthetic cycle discriminate against 13 C more than plants with C4 cycle. We developed a method for analysis of 13 C isotope in organic samples. Because of instrumental requirements carbon must be converted to CO2 for stable isotope ratio measurements. Conversion of organic samples to CO2 was accomplished by combustion in an excess oxygen atmosphere. This technique involves the combustion of individual samples in sealed, evacuated quartz tubes containing CuO as the oxygen source. Because each sample is prepared in its own container, there is no chance for memory effects. The method was tested for sensitivity (the smallest increment of the isotope ratio that must be detected with confidence), sample size (the minimum quantity of a pure molecular species available to achieve the desired accuracy) and precision. The method was utilised for the detection of a synthetic flavour from natural one, namely the natural oil bitter almond from the synthetic benzaldehyde. The method can be validated for the detection or establishment of authenticity in food products. (authors)

  12. Biomineralization and the carbon isotope record

    International Nuclear Information System (INIS)

    The advent of biomineralization at the turn of the Precambrian/Cambrian boundary has been a major event in the Earth's evolutionary history. With this there has been a major shift from abiotic to biotic formation of minerals such as phosphates and carbonates and, subsequently, silica. The dominant factor which effected this shift is a change in ocean's chemistry with respect to its Ca2+ and mineral nutrient contents. Mechanism controlling the biotic mineral formation is different from that controlling the abiotic one in that the former is enzymically controlled. It is suggested that this difference is also manifested in the stable carbon isotope fractionation between the two processes and has implication for the interpretation of stable carbon isotope record. (Author)

  13. Improved isotope ratio measurement performance in liquid chromatography/isotope ratio mass spectrometry by removing excess oxygen.

    Science.gov (United States)

    Hettmann, Elena; Brand, Willi A; Gleixner, Gerd

    2007-01-01

    A low dead volume oxygen scrubbing system was introduced in a commercially available liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) interface to enhance the analytical capability of the system. In the LC/IRMS interface carbon from organic samples is converted into CO(2) inside the mobile phase by wet chemical oxidation using peroxodisulfate (Na(2)S(2)O(8)). After passing the hot reaction zone, surplus oxygen (O(2)) remains dissolved in the liquid phase. Both CO(2) and O(2) diffuse through a transfer membrane into the helium carrier and are transferred to the mass spectrometer. The presence of O(2) in the ion source may have detrimental effects on measurement accuracy and precision as well as on filament lifetime. As a remedy, a new on-line O(2)-removing device has been incorporated into the system. The new O(2) scrubber consists of two parallel hot copper reduction reactors (0.8 mm i.d., active length 120 mm) and a switch-over valve between them. One reactor is regenerated using He/H(2) while the other is actively scavenging O(2) from the gas stream. The capacity of each reduction reactor, expressed as usage time, is between 40 and 50 min. This is sufficient for a single LC run for sugars and organic acids. A further increase of the reduction capacity is accompanied by a peak broadening of about 100%. After switching to a freshly reduced reactor the oxygen background and the delta(13)C values of the reference gas need up to 500 s to stabilize. For repeated injections the delta(13)C values of sucrose remain constant (+/-0.1 per thousand) for about 3000 s. The long-term stability for measurements of sucrose was 0.11 per thousand without the reduction oven and improved slightly to 0.08 per thousand with the reduction oven. The filament lifetime improved by more than 600%, thereby improving the long-term system stability and analytical efficiency. In addition the costs per analysis were reduced considerably. PMID:18041012

  14. The measurement of the isotope ratios and concentrations of zinc by thermal ionization mass spectrometry using double isotope dilution

    International Nuclear Information System (INIS)

    The isotope ratios and concentrations of zinc are measured by silicagel-thermal ionization mass spectrometry using the double isotope spikers. The double isotope spikers (70Zn and 67Zn-enriched isotopes) are used to correct the isotope mass fractionation for the zinc isotope ratios, and to certify the zinc concentrations in the unknown samples. The zinc concentrations of these double isotope spikers are surveyed by a spiker made of pure (99.99%) natural zinc metal powder. The correcting factors (fa, ft and fn) of the zinc isotope ratios in the spiked mixture, spike and unspiked samples for the isotope mass fractionation, and the spike-to-unspiked ratios (Xr) of the zinc isotope r in the spiked mixture samples can be obtained to solve the matrix equations by numerical approximation. The natural zinc isotope ratios are: 64Zn/67Zn = 11.8498, 66Zn/67Zn = 6.7977, 68Zn/67Zn = 4.5730 and 70Zn/67Zn = 0.1520. The uncertainties determined of the isotope ratios and concentrations of zinc are +- 0.16% and +-0.31%, respectively

  15. The lithium isotopic ratio in very metal-poor stars

    CERN Document Server

    Lind, Karin; Asplund, Martin; Collet, Remo; Magic, Zazralt

    2013-01-01

    Un-evolved, very metal-poor stars are the most important tracers of the cosmic abundance of lithium in the early universe. Combining the standard Big Bang nucleosynthesis model with Galactic production through cosmic ray spallation, these stars at [Fe/H]<-2 are expected to show an undetectably small 6Li/7Li isotopic signature. Evidence to the contrary may necessitate an additional pre-galactic production source or a revision of the standard model of Big Bang nucleosynthesis. We revisit the isotopic analysis of four halo stars, two with claimed 6Li-detections in the literature, to investigate the influence of improved model atmospheres and line formation treatment. For the first time, a combined 3D, NLTE (non-local thermodynamic equilibrium) modelling technique for Li, Na, and Ca lines is utilised to constrain the intrinsic line-broadening and to determine the Li isotopic ratio. We discuss the influence of 3D NLTE effects on line profile shapes and assess the realism of our modelling using the Ca excitation...

  16. Isotope ratio monitoring of small molecules and macromolecules by liquid chromatography coupled to isotope ratio mass spectrometry.

    Science.gov (United States)

    Godin, Jean-Philippe; Hau, Jörg; Fay, Laurent-Bernard; Hopfgartner, Gérard

    2005-01-01

    In the field of isotope ratio mass spectrometry, the introduction of an interface allowing the connection of liquid chromatography (LC) and isotope ratio mass spectrometry (IRMS) has opened a range of new perspectives. The LC interface is based on a chemical oxidation, producing CO2 from organic molecules. While first results were obtained from the analysis of low molecular weight compounds, the application of compound-specific isotope analysis by irm-LC/MS to other molecules, in particular biomolecules, is presented here. The influence of the LC flow rate on the CO2 signal and on the observed delta13C values is demonstrated. The limits of quantification for angiotensin III and for leucine were 100 and 38 pmol, respectively, with a standard deviation of the delta13C values better than 0.4 per thousand. Also, accuracy and precision of delta13C values for elemental analyser-IRMS and flow injection analysis-IRMS (FIA-LC/MS) were compared. For compounds with molecular weights ranging from 131 to 66,390 Da, precision was better than 0.3 per thousand, and accuracy varied from 0.1 to 0.7 per thousand. In a second part of the work, a two-dimensional (2D)-LC method for the separation of 15 underivatised amino acids is demonstrated; the precision of delta13C values for several amino acids by irm-LC/MS was better than 0.3 per thousand at natural abundance. For labelled mixtures, the coefficient of variation was between 1% at 0.07 atom % excess (APE) for threonine and alanine, and around 10% at 0.03 APE for valine and phenylalanine. The application of irm-LC/MS to the determination of the isotopic enrichment of 13C-threonine in an extract of rat colon mucosa demonstrated a precision of 0.5 per thousand, or 0.001 atom %. PMID:16124031

  17. Detection of exogenous citric acid in fruit juices by stable isotope ratio analysis.

    Science.gov (United States)

    Jamin, Eric; Martin, Frédérique; Santamaria-Fernandez, Rebeca; Lees, Michèle

    2005-06-29

    A new method has been developed for measuring the D/H ratio of the nonexchangeable sites of citric acid by isotope ratio mass spectrometry (IRMS). Pure citric acid is transformed into its calcium salt and subsequently analyzed by pyrolysis-IRMS. The citric acid isolated from authentic fruit juices (citrus, pineapple, and red fruits) systematically shows higher D/H values than its nonfruit counterpart produced by fermentation of various sugar sources. The discrimination obtained with this simplified method is similar to that obtained previously by applying site specific isotopic fractionation-nuclear magnetic resonance (SNIF-NMR) to an ester derivative of citric acid. The combination of carbon 13 and deuterium measurements of extracted citric acid is proposed as a routine method for an optimum detection of exogenous citric acid in all kinds of fruit juices. PMID:15969486

  18. Carbon to oxygen ratios in extrasolar planetesimals

    Science.gov (United States)

    Wilson, David J.; Gänsicke, Boris T.; Farihi, Jay; Koester, Detlev

    2016-04-01

    Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting onto white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O ) = -0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

  19. Carbon to oxygen ratios in extrasolar planetesimals

    CERN Document Server

    Wilson, David J; Farihi, Jay; Koester, Detlev

    2016-01-01

    Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting onto white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O)=-0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

  20. Dietary heterogeneity among Western industrialized countries reflected in the stable isotope ratios of human hair.

    Science.gov (United States)

    Valenzuela, Luciano O; Chesson, Lesley A; Bowen, Gabriel J; Cerling, Thure E; Ehleringer, James R

    2012-01-01

    Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization). Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ(13)C values (-22.7 to -18.3‰), and significantly higher δ(15)N (7.8 to 10.3‰) and δ(34)S (4.8 to 8.3‰) values than samples from the USA (δ(13)C: -21.9 to -15.0‰, δ(15)N: 6.7 to 9.9‰, δ(34)S: -1.2 to 9.9‰). Within Europe, we detected differences in hair δ(13)C and δ(34)S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments. PMID:22479574

  1. Last Glacial Maximum and deglacial abyssal seawater oxygen isotopic ratios

    Science.gov (United States)

    Wunsch, Carl

    2016-06-01

    An earlier analysis of pore-water salinity (chlorinity) in two deep-sea cores, using terminal constraint methods of control theory, concluded that although a salinity amplification in the abyss was possible during the LGM, it was not required by the data. Here the same methodology is applied to δ18Ow in the upper 100 m of four deep-sea cores. An ice volume amplification to the isotopic ratio is, again, consistent with the data but not required by it. In particular, results are very sensitive, with conventional diffusion values, to the assumed initial conditions at -100 ky and a long list of noise (uncertainty) assumptions. If the calcite values of δ18O are fully reliable, then published enriched values of the ratio in seawater are necessary to preclude sub-freezing temperatures, but the seawater δ18O in pore fluids does not independently require the conclusion.

  2. Determination of uranium and its isotopic ratios in environmental samples

    International Nuclear Information System (INIS)

    A method for the determination of uranium and its isotopic ratios ( sup(235)U/ sup(238)U and sup(234U/ sup(238)U) is established in the present work. The method can be applied in environmental monitoring programs of uranium enrichment facilities. The proposed method is based on the alpha spectrometry technique which is applied after a purification of the sample by using an ionic exchange resin. The total yield achieved was (91 + 5)% with a precision of 5%, an accuracy of 8% and a lower limit of detection of 7,9 x 10 sup(-4)Bq. The uranium determination in samples containing high concentration of iron, which is an interfering element present in environmental samples, particularly in soil and sediment, was also studied. The results obtained by using artificial samples containing iron and uranium in the ratio 1000:1, were considered satisfactory. (author)

  3. A carbon isotope survey of South African honey

    International Nuclear Information System (INIS)

    Stable carbon isotope analysis has been successfully employed in various fields, including botany, geochemistry, archaeology and, more recently, as an analytical tool in the food industry. In the analysis of food, it has been primarily directed at quality control and the detection of cheap adulterants to 'natural' foods. The method is based on the known characteristic of differences in the 13C to 12C ratios produced by two groups of plants with different photosynthetic mechanisms, known as C3 and C4. This patterning is useful because the cheapest sources of alcohol, sweeteners and flavourings are derived from C4 plants, maize and sugar cane, whereas traditional Old World sources such as grapes, nectar and fruit are derived from C3 plants. The results of an informal isotopic survey of South African honeys are reported. This isotopic method is particularly useful in that it is not possible to circumvent it by manipulation of the sugars or any of the other constituents

  4. Evaluation on nitrogen isotopes analysis in high-C/N-ratio plants using elemental analyzer/isotope ratio mass spectrometry

    International Nuclear Information System (INIS)

    Elemental analyzer/isotope ratio mass spectrometry (EA/IRMS) has been widely applied to analyze the 15N/14N isotope composition (δ15N) of plants and soils, but the δ15N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA. Therefore, it is necessary to develop a method to solve the problem of imperfect combustion. In this study, we used two methods: 1) adding copper oxide powder to the samples, and 2) increasing the O2 flow (from 100 mL min-1 to 200 mL min-1) for the auto sampler inlet purge line of the EA. The δ15N values of the plant samples became more positive and tended to be stable after complete combustion. Also, the required blank samples for each plant sample decreased with increasing amount of the added CuO powder. However, at 200 mL min-1 of the oxygen flow in the EA, complete combustion could not be achieved without adding copper oxide, but this was done with decreased amount of CuO powder. Therefore, mixing cupric oxide into the high-C/N-ratio samples was an efficient, simple and convenient way to solve the problem of imperfect combustion in the EA. (authors)

  5. CO (Carbon Monoxide Mixing Ratio System) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Biraud, S

    2011-02-23

    The main function of the CO instrument is to provide continuous accurate measurements of carbon monoxide mixing ratio at the ARM SGP Central Facility (CF) 60-meter tower (36.607 °N, 97.489 °W, 314 meters above sea level). The essential feature of the control and data acquisition system is to record signals from a Thermo Electron 48C and periodically calibrate out zero and span drifts in the instrument using the combination of a CO scrubber and two concentrations of span gas (100 and 300 ppb CO in air). The system was deployed on May 25, 2005.

  6. Field Sample Preparation Method Development for Isotope Ratio Mass Spectrometry

    International Nuclear Information System (INIS)

    Non-proliferation and International Security (NA-241) established a working group of researchers from Los Alamos National Laboratory (LANL), Pacific Northwest National Laboratory (PNNL) and Savannah River National Laboratory (SRNL) to evaluate the utilization of in-field mass spectrometry for safeguards applications. The survey of commercial off-the-shelf (COTS) mass spectrometers (MS) revealed no instrumentation existed capable of meeting all the potential safeguards requirements for performance, portability, and ease of use. Additionally, fieldable instruments are unlikely to meet the International Target Values (ITVs) for accuracy and precision for isotope ratio measurements achieved with laboratory methods. The major gaps identified for in-field actinide isotope ratio analysis were in the areas of: 1. sample preparation and/or sample introduction, 2. size reduction of mass analyzers and ionization sources, 3. system automation, and 4. decreased system cost. Development work in 2 through 4, numerated above continues, in the private and public sector. LANL is focusing on developing sample preparation/sample introduction methods for use with the different sample types anticipated for safeguard applications. Addressing sample handling and sample preparation methods for MS analysis will enable use of new MS instrumentation as it becomes commercially available. As one example, we have developed a rapid, sample preparation method for dissolution of uranium and plutonium oxides using ammonium bifluoride (ABF). ABF is a significantly safer and faster alternative to digestion with boiling combinations of highly concentrated mineral acids. Actinides digested with ABF yield fluorides, which can then be analyzed directly or chemically converted and separated using established column chromatography techniques as needed prior to isotope analysis. The reagent volumes and the sample processing steps associated with ABF sample digestion lend themselves to automation and field

  7. Isotope ratio analysis of individual uranium particles for safeguards

    International Nuclear Information System (INIS)

    Japan Atomic Energy Research Institute (JAERI) was qualified, in January 2003, as a member of the IAEA network analytical laboratories (NWALs) for particle and bulk analyses of safeguards environmental samples. The particle analysis gives more detailed information on nuclear facility operation than the bulk analysis because the isotope ratios of nuclear materials in the samples collected inside nuclear facilities (swipe samples) can be determined for individual particles. We applied secondary ion mass spectrometry (SIMS) to the uranium isotope ratio measurement for particle analysis. Prior to the SIMS analysis, the particles in a swipe sample are recovered onto a carrier by impaction. The carriers with the recovered particles are then screened by total reflection X-ray fluorescence spectrometry. We integrated these techniques into a standard procedure, which is applied to domestic and IAEA swipe samples routinely. For the analysis of the particles with the diameter smaller than 1 μm, with which the SIMS has insufficient sensitivity, we are developing a more sensitive method, the combination of fission track detection and thermal ionization mass spectrometry. (author)

  8. Understanding radioxenon isotopical ratios originating from radiopharmaceutical facilities

    Science.gov (United States)

    Saey, P. R. J.; Ringbom, A.; Bowyer, T. W.; Becker, A.; de Geer, L.-E.; Nikkinen, M.; Payne, R. F.

    2009-04-01

    It was recently shown that radiopharmaceutical facilities (RPF) are major contributors to the general background of 133Xe and other xenon isotopes both in the northern and southern hemisphere. To distinguish a nuclear explosion signal from releases from civil nuclear facilities, not only the activity concentrations but also the ratios of the four different CTBT relevant radioxenon isotopes (131mXe, 133mXe, 133Xe and 135Xe) have to be well understood. First measurements taken recently in and around two of the world's largest RPF's: NTP at Pelindaba, South Africa and IRE at Fleurus, Belgium have been presented. At both sites, also stack samples were taken in close cooperation with the facility operators. The radioxenon in Belgium could be classified in four classes: the normal European background (133Xe activity between 0 - 5 mBq/m3) on one hand and then the samples where all four isotopes were detected with 133mXe/131mXe > 1. In northern South Africa the Pelindaba RPF is in practice the sole source of radioxenon. It generated a background of 133Xe at the measurement site some 230 km to the west of the RPF of 0 - 5 mBq/m3. In the cases where the air from the Pelindaba facility reached the measurement site directly and in a short time period, the 133Xe was higher, also 135Xe was present and in some samples 133mXe as well. The ratios of the activity concentrations of 135Xe/133Xe vs. 133mXe/131mXe (Multiple Isotope Ratio Plot - MIRC) have been analysed. For both facilities, the possible theoretical ratio's for different scenarios were calculated with the information available and compared with the measurements. It was found that there is an excess of 131mXe present in the European samples compared to theoretical calculations. A similar excess has also been seen in samples measured in northern America. In South Africa, neither the environmental samples nor the stack ones contained 131mXe at measurable levels. This can probably be explained by different processes and

  9. Abundances in red giant stars - Carbon and oxygen isotopes in carbon-rich molecular envelopes

    Science.gov (United States)

    Wannier, P. G.; Sahai, R.

    1987-01-01

    Millimeter-wave observations have been made of isotopically substituted CO toward the envelopes of 11 carbon-rich stars. In every case, C-13O was detected and model calculations were used to estimate the C-12/C-13 abundance ratio. C-17O was detected toward three, and possibly four, envelopes, with sensitive upper limits for two others. The CO-18 variant was detected in two envelopes. New results include determinations of oxygen isotopic ratios in the two carbon-rich protoplanetary nebulae CRL 26688 and CRL 618. As with other classes of red giant stars, the carbon-rich giants seem to be significantly, though variably, enriched in O-17. These results, in combination with observations in interstellar molecular clouds, indicate that current knowledge of stellar production of the CNO nuclides is far from satisfactory.

  10. Do stable carbon isotopes of brown coal woods record changes in Lower Miocene palaeoecology?

    NARCIS (Netherlands)

    Poole, I.J.; Dolezych, M.; Kool, J.; Burgh, J. van der; Bergen, P.F. van

    2006-01-01

    Stable carbon isotope ratios of fossil wood from the Miocene brown coal deposits in former East Germany are compared with palaeobotanical and sedimentological data to test the use of stable isotopes in determining palaeoenvironment. Significant differences in the chemical composition of samples from

  11. Sulfur isotope ratios and the origins of the aerosols and cloud droplets in California stratus

    OpenAIRE

    Ludwig, F. L.

    2011-01-01

    Marine aerosols often have sulfur-to-chloride ratios greater than that found in seawater. Sulfur isotope ratios (34S/32S) were measured in aerosol and cloud droplet samples collected in the San Francisco Bay Area in an attempt to understand the processes that produce the observed sulfur-to-chloride ratios. Seawater sulfur usually has very high sulfur isotope ratios; fossil fuel sulfur tends to have smaller isotope ratios and sulfur of bacteriogenic origin still smaller. Samples collected in u...

  12. Sulfur isotope in nature. Determination of sulfur isotope ratios in coal and petroleum by mass spectrometry

    International Nuclear Information System (INIS)

    Elementary sulfur or in chemical compounds is one of the elements widespread in the earth's crust and biosphere. Its participation in earth's crust amounts to 0.26 % by weight. Measurement of isotope composition of natural samples can deliver many information about origin, creation and transformation ranges of rocks and minerals. Sulfur isotope ratio contained in minerals is variable and for this reason investigation of isotope sulfur composition can deliver useful information about the geochemistry of each component. Therefore in the investigated sample it is necessary to determine not only the content of sulfur but also the isotope composition of each component. Differentiation of contents of sulfur-34 in natural sulfur compounds can reach up to 110 per mile. So large divergences can be explained by a kinetic effect or by bacterial reduction of sulphates. In this report a wide review of the results of investigations of isotope sulfur compositions in coal and petroleum are presented as well as the methods for the preparation of samples for mass spectrometry analysis are proposed. (author)

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

    International Nuclear Information System (INIS)

    Currently, one of the stages in nuclear fuel cycle development is the process of uranium isotope enrichment, which will provide the amount of low enriched uranium for the nuclear fuel production to supply 100% Angra 1 and 20% Angra 2 demands. Determination of isotopic ration n(235U)/n(238U) in uranium hexafluoride (UF6 - used as process gas) is essential in order to control of enrichment process of isotopic separation by gaseous centrifugation cascades. The uranium hexafluoride process is performed by gas continuous feeding in separation unit which uses the centrifuge force principle, establishing a density gradient in a gas containing components of different molecular weights. The elemental separation effect occurs in a single ultracentrifuge that results in a partial separation of the feed in two fractions: an enriched on (product) and another depleted (waste) in the desired isotope (235UF6). Industrias Nucleares do Brasil (INB) has used quadrupole mass spectrometry (QMS) by electron impact (EI) to perform isotopic ratio n(235U)/n(238U) analysis in the process. The decision of adjustments and change te input variables are based on the results presented in these analysis. A study of stability, bias and linearity determination has been performed in order to evaluate the applied method, variations and systematic errors in the measurement system. The software used to analyze the techniques above was the Minitab 15. (author)

  14. Sulfur isotopic ratio of DMS and DMSP from Lake Kinneret

    Science.gov (United States)

    Sela-Adler, Michal; Said-Ahmad, Ward; Eckert, Werner; Kamyshny, Alexey; Sivan, Orit; Amrani, Alon

    2014-05-01

    Volatile Organic sulfur compounds (VOSC) such as dimethylsulfide (DMS) are an important source of biogenic sulfur to the atmosphere. The main precursor of DMS is dimethylsulfoniopropionate (DMSP), a common osmolyte in marine algae. Atmospheric release of VOS compounds contributes to the formation of sulfate aerosols. The latter are of global importance due to their role as cloud-condensation nuclei. VOSC are abundant in terrestrial environments as well and may be involved in important biogeochemical cycles. In lake sediments, another mechanism for the formation of DMS by H2S methylation may be important. The 34S/32S ratio (d34S values) of DMSP of marine surface water around the globe is very homogeneous ranging between +18.9 o to +20.3 o and the fractionation between DMSP and DMS is water algae by using sulfur isotope ratios. Water column samples and sediment samples from Lake Kinneret were purged and trap in order to extract the VOSC and then introduced to a GC/MC-ICPMS for isotopic measurements (Amrani et al. 2013). The δ34S of DMSP in the water and sediment columns of Lake Kinneret a mesotrophic monomictic lake were measured. Our preliminary results show δ34S values for DMSP ranged between +10.3 o and +13.4 o in the water column. The sulfate δ34S values ranged between +12.6 o to +14.9 o. δ34S -DMSP in the sediment column showed similar values between +9.4 o and +13.0 o, indicating a similar sulfur source. Similar δ34S values obtain for other VOSC such as ethanethiol that contributes significantly to the VOSC of Lake Kinneret sediments. Amrani, A., W. Said-Ahmad,Y. Shaked, and R. P. Kiene. 2013. Sulfur isotopes homogeneity of oceanic DMSP and DMS. PNAS 110(46):18413-18418. Oduro, H., Kamyshny, A. Jr.,W. Guo, and J. Farquhar. 2011. Multiple sulfur isotopes analysis of volatile organic sulfur compounds and their sulfonium precursors in marine coastal environments. Marine Chemistry 124:78-89.

  15. Geographical variations in Sr and Nd isotopic ratios of cryoconite on Asian glaciers

    International Nuclear Information System (INIS)

    Cryoconite is a dark-coloured surface dust deposited on glaciers that consists of wind-blown mineral particles, as well as organic matter derived from microbes living on glaciers. In this paper, we analyse the Sr and Nd isotopic ratios of four mineral fractions (i.e., the saline, carbonate, phosphate, and silicate mineral fractions), as well as the organic fraction, of cryoconite samples obtained from six Asian glaciers (the Altai, Pamir, Tien Shan, Qillian Shan, and Himalayan regions), and discuss their geographical variations in terms of the geological origins of the mineral particles and the biogeochemical processes on the glaciers. The silicate mineral fraction showed lower Sr and higher Nd ratios for the glaciers located to the north (Altai, 87Sr/86Sr: 0.713 490–0.715 284, εNd(0): −6.4 to −5.6), while higher Sr and lower Nd ratios for the glaciers located to the south (Himalayas, 87Sr/86Sr: 0.740 121–0.742 088, εNd(0): −16.4 to −15.7); the ratios were similar to those of desert sand, loess, and river sediments in the respective regions of the glaciers. This result suggests that the silicate minerals within the cryoconites were derived from different sources depending on the geographical locations of the glaciers. The isotopic ratios of the saline, carbonate, and phosphate mineral fractions were distinct from those of the silicate fraction, and were similar to those of evaporites and apatite deposits from the Asian deserts, but also varied geographically, indicating that they are likely to reflect their geological origin. The Sr isotopic ratios of the organic fraction were similar to those of the saline and carbonate fractions from glaciers in the central area (Tien Shan and Qillian Shan), but were higher than those of the saline and carbonate fractions, and lower than the phosphate mineral fraction, in the northern and southern areas. The ratios of organic fraction may be determined from the mixing ratio of calcium sources incorporated by

  16. Carbon to oxygen ratios in extrasolar planetesimals

    Science.gov (United States)

    Wilson, David J.; Gänsicke, Boris T.; Farihi, Jay; Koester, Detlev

    2016-07-01

    Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting on to white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O systems. Our results place an upper limit on the occurrence of carbon-rich systems at Solar system, and appears to follow a bimodal distribution: a group similar to the CI chondrites, with log () = -0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

  17. Using Oxygen Isotopes in Fish Scale Apatite to Reconstruct Past Temperatures and Water Isotope Ratios

    Science.gov (United States)

    Lambert, T. D.; Paytan, A.

    2009-12-01

    Oxygen isotope ratios (δ18O) of apatite phosphate in fish bones and teeth vary according to the temperature and δ18O of water during formation. Since isotope ratios in apatite are often well preserved over geologic timescales, fish bones and teeth have been used to determine past environmental conditions. Fish scales offer several advantages over bones and teeth: they are relatively common in certain sedimentary basins, and they are more easily identified to species level. Analysis of paired bone and scale samples will be presented. The data indicate that fish scale apatite similarly records environmental conditions during growth. Thus δ18O of apatite phosphate in fish scales may provide useful paleoecological information and also indicate past environmental conditions.

  18. Boron isotope fractionation in magma via crustal carbonate dissolution

    Science.gov (United States)

    Deegan, Frances M.; Troll, Valentin R.; Whitehouse, Martin J.; Jolis, Ester M.; Freda, Carmela

    2016-08-01

    Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to ‑41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

  19. Magnesium isotope fractionation in bacterial mediated carbonate precipitation experiments

    Science.gov (United States)

    Parkinson, I. J.; Pearce, C. R.; Polacskek, T.; Cockell, C.; Hammond, S. J.

    2012-12-01

    Magnesium is an essential component of life, with pivotal roles in the generation of cellular energy as well as in plant chlorophyll [1]. The bio-geochemical cycling of Mg is associated with mass dependant fractionation (MDF) of the three stable Mg isotopes [1]. The largest MDF of Mg isotopes has been recorded in carbonates, with foraminiferal tests having δ26Mg compositions up to 5 ‰ lighter than modern seawater [2]. Magnesium isotopes may also be fractionated during bacterially mediated carbonate precipitation and such carbonates are known to have formed in both modern and ancient Earth surface environments [3, 4], with cyanobacteria having a dominant role in carbonate formation during the Archean. In this study, we aim to better constrain the extent to which Mg isotope fractionation occurs during cellular processes, and to identify when, and how, this signal is transferred to carbonates. To this end we have undertaken biologically-mediated carbonate precipitation experiments that were performed in artificial seawater, but with the molar Mg/Ca ratio set to 0.6 and with the solution spiked with 0.4% yeast extract. The bacterial strain used was marine isolate Halomonas sp. (gram-negative). Experiments were run in the dark at 21 degree C for two to three months and produced carbonate spheres of various sizes up to 300 μm in diameter, but with the majority have diameters of ~100 μm. Control experiments run in sterile controls (`empty` medium without bacteria) yielded no precipitates, indicating a bacterial control on the precipitation. The carbonate spheres are produced are amenable to SEM, EMP and Mg isotopic analysis by MC-ICP-MS. Our new data will shed light on tracing bacterial signals in carbonates from the geological record. [1] Young & Galy (2004). Rev. Min. Geochem. 55, p197-230. [2] Pogge von Strandmann (2008). Geochem. Geophys. Geosys. 9 DOI:10.1029/2008GC002209. [3] Castanier, et al. (1999). Sed. Geol. 126, 9-23. [4] Cacchio, et al. (2003

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

    OpenAIRE

    Petach, Tanya N.

    2015-01-01

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

  1. Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

    Science.gov (United States)

    Annewandter, Robert

    2014-05-01

    The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced gas transport and subsequent soil gas sampling during On-Site inspections. Generally, gas transport has been widely studied with different numerical codes. However, gas transport of radioxenons and radioiodines in the post-detonation regime and their possible fractionation is still neglected in the open peer-reviewed literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the multiple isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radionuclides, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different mass diffusivities due to mass differences between the radionuclides. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures or highly conductive faults which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a so-called ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which is recognized by the oil industry as leading in Discrete Fracture-Matrix (DFM) simulations. It has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations, fracture propagation in fractured, porous media, and Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic differential equations by a complementary finite

  2. Source Attribution of Cyanides Using Anionic Impurity Profiling, Stable Isotope Ratios, Trace Elemental Analysis and Chemometrics.

    Science.gov (United States)

    Mirjankar, Nikhil S; Fraga, Carlos G; Carman, April J; Moran, James J

    2016-02-01

    Chemical attribution signatures (CAS) for chemical threat agents (CTAs), such as cyanides, are being investigated to provide an evidentiary link between CTAs and specific sources to support criminal investigations and prosecutions. Herein, stocks of KCN and NaCN were analyzed for trace anions by high performance ion chromatography (HPIC), carbon stable isotope ratio (δ(13)C) by isotope ratio mass spectrometry (IRMS), and trace elements by inductively coupled plasma optical emission spectroscopy (ICP-OES). The collected analytical data were evaluated using hierarchical cluster analysis (HCA), Fisher-ratio (F-ratio), interval partial least-squares (iPLS), genetic algorithm-based partial least-squares (GAPLS), partial least-squares discriminant analysis (PLSDA), K nearest neighbors (KNN), and support vector machines discriminant analysis (SVMDA). HCA of anion impurity profiles from multiple cyanide stocks from six reported countries of origin resulted in cyanide samples clustering into three groups, independent of the associated alkali metal (K or Na). The three groups were independently corroborated by HCA of cyanide elemental profiles and corresponded to countries each having one known solid cyanide factory: Czech Republic, Germany, and United States. Carbon stable isotope measurements resulted in two clusters: Germany and United States (the single Czech stock grouped with United States stocks). Classification errors for two validation studies using anion impurity profiles collected over five years on different instruments were as low as zero for KNN and SVMDA, demonstrating the excellent reliability associated with using anion impurities for matching a cyanide sample to its factory using our current cyanide stocks. Variable selection methods reduced errors for those classification methods having errors greater than zero; iPLS-forward selection and F-ratio typically provided the lowest errors. Finally, using anion profiles to classify cyanides to a specific stock

  3. Stable isotope ratio analysis to differentiate temporal diets of a free-ranging herbivore.

    Science.gov (United States)

    Walter, W D; Leslie, D M

    2009-07-01

    Stable isotope ratio analysis (SIRA) of carbon (delta13C) and nitrogen (delta15N) in tissue samples of herbivores can identify photosynthetic pathways (C3 vs. C4) of plants consumed. We present results from free-ranging Rocky Mountain elk (Cervus elaphus) that highlight the ability to differentiate diets using tissue delta13C and delta15N. The signatures of delta13C and delta15N differed in tissues of varying metabolic activity: muscle, a short-term dietary indicator (i.e., 1-2 months) and hoof, a long-term dietary indicator (i.e., 3-12 months). We also documented that delta13C and delta15N values along elk hooves (proximal, middle, distal sections) elucidated temporal shifts in dietary selection. The carbon isotopes of the composite hoof were similar to those of the middle section, but the composite hoof differed in delta(13)C from the distal and proximal sections. The delta13C and delta15N signatures also differed among elk populations, indicating temporal dietary shifts of individuals occupying disparate native range and human-derived agricultural landscapes. Analyses of stable isotopes in various tissues highlighted carbon and nitrogen assimilation through time and differences in the foraging ecology of a rangeland herbivore. PMID:19530151

  4. Carbon monoxide isotope fractionation in the dust cloud Lynds 134

    International Nuclear Information System (INIS)

    Prior observations of isotopically substituted CO in Lynds 134 are used to discuss the spatial behavior of the [CO]/[13CO] abundance ratio as a function of visual extinction in the cloud. [CO]/[13CO] is determined from both LTE and non-LTE evaluations of the double ratio [13CO]/: C18O] by subsequent application of an assumed constant, terrestrial oxygen isotope ratio. It is found that [CO]/[13CO] is roughly terrestrial toward the central regions of L134 where A/sub ν/> or approx. =7 mag, and decreases in the cloud periphery where A/sub ν/ is lower. These results are in qualitative agreement with theoretical expectation for a low-temperature, chemically fractionated dark cloud, in which preferential 13CO enhancement is driven in low-extinction regions by the charge exchange 13C++12CO→12C+13CO. The impact of this result on previous studies of the carbon isotope ratio [12C]/[13C] in the sense interstellar medium is discussed

  5. A New Multi Collector Isotope Ratio Mass Spectrometer

    Science.gov (United States)

    Appelhans, A. D.; Olson, J. E.; Ward, M. B.; Dahl, D. A.

    2007-12-01

    With the goal of improving the sensitivity of isotope ratio measurements, particularly for actinides, a new magnetic sector mass spectrometer that utilizes up to seven full-sized discrete dynode electron multipliers operating simultaneously has been designed, constructed and is in the early stages of testing. The design is based on a newly developed ion dispersion lens that enables the mass dispersed individual isotope beams to be separated by 35 mm; this allows a full-sized discrete dynode pulse counting multiplier to be used for each beam. The ion dispersion lens (US patents 6,297,501 and pending) is a two element electrostatic 90 degree sector device that causes the beam-to-beam dispersion to increase faster than the intra-beam dispersion. Each of the multipliers is housed in an isolated case and is equipped with a deflector/condenser lens at the entrance to optimize pulse generation. The instrument includes a 9-sample filament cartridge mounted on a micro-manipulator X-Y stage that enables adjustment of the filament position with 10 micron resolution within the ion lens. Initial testing has shown that the instrument is performing as predicted by the ion optics model of the design.

  6. Estudo de adulteração em méis brasileiros através de razão isotópica do carbono A study of adulteration in brazilian honeys by carbon isotope ratio

    Directory of Open Access Journals (Sweden)

    Cibele Regina de Souza-Kruliski

    2010-04-01

    Full Text Available Neste trabalho, objetivou-se analisar isotopicamente méis comercializados nas regiões Sul e Sudeste do Brasil, para a detecção de fraude. Foram colhidas amostras comerciais com registro no Serviço de Inspeção Federal, Estadual ou Municipal. As amostras foram submetidas à combustão no Analisador Elementar EA 1108 CHN e analisadas no espectrômetro de massas de razão isotópica DELTA-S (Finningan Mat. Os valores isotópicos (δ13C dos méis in natura foram comparados aos de suas respectivas proteínas (padrão interno. Foram consideradas adulteradas as amostras cuja diferença entre o valor isotópico da proteína e do mel foi igual ou inferior a -1‰. As amostras consideradas adulteradas pela análise isotópica foram submetidas a testes químicos qualitativos que não foram capazes de indicar adulteração para algumas delas. Das 61 amostras analisadas, 18,0% encontram-se adulteradas, sendo 11,5% na Região Sudeste e 6,5% na Região Sul. Ao contrário dos testes químicos, a análise isotópica mostrou-se eficaz em identificar e quantificar a adulteração de méis comerciais.The aim of this study was the isotopic evaluation of honey traded in the Southern and Southeastern Brazilian regions, to detect fraud. Commercial samples, registered in the municipal, State or Federal Inspection Service, were collected and submitted to combustion in the EA 1108 CHN Elemental Analyzer and analyzed in the DELTA-S (Finningan Mat. isotope ratio mass spectrometer. The isotopic values (δ13C of in natura honey were compared to their respective proteins (internal standard. Samples whose difference between the isotopic value of protein and honey was equal or inferior to -1‰ were considered adulterated. The samples considered adulterated were submitted to qualitative chemical tests which were unable to show adulteration for some of them. Among the 61 samples analyzed, 18.0% were adulterated; 11.5% in the Southeastern and 6.5% in the Southern region

  7. Application of carbon and oxygen stable isotopes to the study of Brazilian precambrian

    International Nuclear Information System (INIS)

    Samples of carbonated rocks of precambrian age are studied. The stable carbon and oxygen isotopes are applied to the study of terrestrial materials considering the variations of some element isotopic composition in function of the environment of sedimentation. The isotopic analysis was done using mass spectrometers. The analytical results and the description of region geology of the site of each sample are presented. The isotopic data are interpreted aiming to the environment of sedimentation. New techniques for better improvement of carbon and oxygen ratios, are proposed, such as: to use the analysis of surface trend and the isotopic logging in mapping of surface and subsurface. A new method for approximated determination of the ages of precambrian carbonated rocks, considering the limitations of their new technique, is also presented. (M.C.K.)

  8. Romanian wines characterization with CF-IRMS (Continuous Flow Isotope Ratio Mass Spectrometry) isotopic analysis

    International Nuclear Information System (INIS)

    Wine growing has been known for centuries long in Romania. The country has been favored by its geographical position in south-eastern Europe, by its proximity to the Black Sea, as well as by the specificity of the local soil and climate. Alongside France, Italy, Spain, Germany, countries in this area like Romania could also be called 'a vine homeland' in Europe. High quality wines produced in this region were object of trade ever since ancient times. Under current EU research projects, it is necessary to develop new methods of evidencing wine adulteration and safety. The use of mass spectrometry (MS) to determine the ratios of stable isotopes in bio-molecules now provides the means to prove the botanical and geographical origin of a wide variety of foodstuffs - and therefore, to authenticate and eliminate fraud. Isotope analysis has been officially adopted by the EU as a means of controlling adulteration of wine. Adulteration of wine can happen in many ways, e.g. addition of non-grape ethanol, addition of non-grape sugar, water or other unauthorized substances, undeclared mixing of wines from different wards, geographical areas or countries, mislabelling of variety and age. The present paper emphasize the isotopic analysis for D/H, 18O/16O, 13C/12C from wines, using a new generation Isotope Ratio MS, Finnigan Delta V Plus, coupling with a three flexible continuous flow preparation device (GasBench II, TC Elemental Analyser and GC-C/TC). Therefore authentication of wines is an important problem to which isotopic analysis has made a significant contribution. (authors)

  9. Carbonate clumped isotope bond reordering and geospeedometry

    Science.gov (United States)

    Passey, Benjamin H.; Henkes, Gregory A.

    2012-10-01

    Carbonate clumped isotope thermometry is based on the preference of 13C and 18O to form bonds with each other. At elevated temperatures such bond ordering is susceptible to resetting by diffusion of C and O through the solid mineral lattice. This type of bond reordering has the potential to obscure primary paleoclimate information, but could also provide a basis for reconstructing shallow crustal temperatures and cooling rates. We determined Arrhenius parameters for solid-state reordering of C-O bonds in two different calcites through a series of laboratory heating experiments. We find that the calcites have different susceptibilities to solid-state reordering. Reaction progress follows a first order rate law in both calcites, but only after an initial period of non-first order reaction that we suggest relates to annealing of nonequilibrium defects when the calcites are first heated to experimental temperature. We show that the apparent equilibrium temperature equations (or "closure temperature" equations) for carbonate clumped isotope reordering are analogous Dodson's equations for first order loss of daughter isotopes. For each calcite, the sensitivity of apparent equilibrium temperature to cooling rate is sufficiently high for inference of cooling rates within a factor of ˜5 or better for cooling rates ranging from tens of degrees per day to a few degrees per million years. However, because the calcites have different susceptibilities to reordering, each calcite defines its own cooling rate-apparent equilibrium temperature relationship. The cooling rates of Carrara marble inferred from carbonate clumped isotope geospeedometry are 10-6-10-3 degrees per annum and are in broad agreement with rates inferred from thermochronometric methods. Cooling rates for 13C-depleted calcites from the late Neoproterozoic Doushantou cap carbonates in south China are on the order of 102-104 degrees per annum, consistent with rapid cooling following formation of these calcites by a

  10. Dependence of the precision of uranium isotope ratio on particle diameter in individual particle analysis with SIMS

    International Nuclear Information System (INIS)

    The dependence of the precision of uranium isotope ratio on particle diameter in secondary ion mass spectrometry (SIMS) was investigated. Each uranium particle in certified reference materials with different isotopic composition (235U/238U = 0.01-1.00) was observed with a scanning electron microscope (SEM) and transferred by a manipulator on a glassy-carbon planchet for subsequent isotope ratio analysis with SIMS. The relative standard deviation (RSD) of uranium isotope ratios varied with particle diameter, the amount of less abundant uranium isotope and the number of measurement cycles. For the particle with the diameter less than 1.0 μm, the RSD significantly increased with increasing the number of measurement cycles, which is due to the difficulty of obtaining constant signals for a long duration. In contrast, no significant increase in the RSD was observed in the analysis of the particle with the diameter larger than 2.0 μm. As the results, it is estimated that the 235U amount of 4.5 fg is sufficient to obtain the 235U/238U ratio with the RSD within 5.0%. For the analysis of minor isotopes, the 234U amount of 0.42 fg and the 236U amount of 1.1 fg are sufficient to obtain the 234U/238U and 236U/238U ratios with the RSD within 20%, respectively

  11. Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania

    International Nuclear Information System (INIS)

    Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ18O and δ2H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ18O and δ2H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source

  12. Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania

    Science.gov (United States)

    Magdas, D. A.; Cristea, G.; Cordea, D. V.; Bot, A.; Puscas, R.; Radu, S.; Mirel, V.; Mihaiu, M.

    2013-11-01

    Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ18O and δ2H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ18O and δ2H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

  13. Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania

    Energy Technology Data Exchange (ETDEWEB)

    Magdas, D. A., E-mail: gabriela.cristea@itim-cj.ro; Cristea, G., E-mail: gabriela.cristea@itim-cj.ro; Bot, A.; Puscas, R.; Radu, S.; Mirel, V. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca (Romania); Cordea, D. V.; Mihaiu, M. [University of Agricultural Science and Veterinary Medicine, 3-5 Calea Manastur, 400372 Cluj-Napoca (Romania)

    2013-11-13

    Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ{sup 18}O and δ{sup 2}H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ{sup 18}O and δ{sup 2}H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

  14. Carbon to oxygen ratios in extrasolar planetesimals

    Science.gov (United States)

    Wilson, David J.; Gänsicke, Boris T.; Farihi, Jay; Koester, Detlev

    2016-04-01

    Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting onto white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O confidence level. The range of C/O of the planetesimals is consistent with that found in the Solar System, and appears to follow a bimodal distribution: a group similar to the CI chondrites, with log ( ) = -0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

  15. Source Attribution of Cyanides using Anionic Impurity Profiling, Stable Isotope Ratios, Trace Elemental Analysis and Chemometrics

    Energy Technology Data Exchange (ETDEWEB)

    Mirjankar, Nikhil S.; Fraga, Carlos G.; Carman, April J.; Moran, James J.

    2016-01-08

    Chemical attribution signatures (CAS) for chemical threat agents (CTAs) are being investigated to provide an evidentiary link between CTAs and specific sources to support criminal investigations and prosecutions. In a previous study, anionic impurity profiles developed using high performance ion chromatography (HPIC) were demonstrated as CAS for matching samples from eight potassium cyanide (KCN) stocks to their reported countries of origin. Herein, a larger number of solid KCN stocks (n = 13) and, for the first time, solid sodium cyanide (NaCN) stocks (n = 15) were examined to determine what additional sourcing information can be obtained through anion, carbon stable isotope, and elemental analyses of cyanide stocks by HPIC, isotope ratio mass spectrometry (IRMS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), respectively. The HPIC anion data was evaluated using the variable selection methods of Fisher-ratio (F-ratio), interval partial least squares (iPLS), and genetic algorithm-based partial least squares (GAPLS) and the classification methods of partial least squares discriminate analysis (PLSDA), K nearest neighbors (KNN), and support vector machines discriminate analysis (SVMDA). In summary, hierarchical cluster analysis (HCA) of anion impurity profiles from multiple cyanide stocks from six reported country of origins resulted in cyanide samples clustering into three groups: Czech Republic, Germany, and United States, independent of the associated alkali metal (K or Na). The three country groups were independently corroborated by HCA of cyanide elemental profiles and corresponded to countries with known solid cyanide factories. Both the anion and elemental CAS are believed to originate from the aqueous alkali hydroxides used in cyanide manufacture. Carbon stable isotope measurements resulted in two clusters: Germany and United States (the single Czech stock grouped with United States stocks). The carbon isotope CAS is believed to

  16. Unusual stable isotope ratios in amino acid and carboxylic acid extracts from the Murchison meteorite

    Science.gov (United States)

    Epstein, S.; Krishnamurthy, R. V.; Cronin, J. R.; Pizzarello, S.; Yuen, G. U.

    1987-01-01

    The isotopic composition of hydrogen, nitrogen, and carbon in amino acid and monocarboxylic acid extracts from the Murchison meteorite has been determined. The unusually high D/H and N-15/N-14 ratios in the amino acid fraction are uniquely characteristic of known interstellar organic materials. The delta D value of the monocarboxylic acid fraction is lower but still consistent with an interstellar origin. These results confirm the extraterrestrial origin of both classes of compound and provide the first evidence suggesting a direct relationship between the massive organosynthesis occurring in interstellar clouds and the presence of prebiotic compounds in primitive planetary bodies.

  17. Emission ratio and isotopic signatures of molecular hydrogen emissions from tropical biomass burning

    Science.gov (United States)

    Haumann, F. A.; Batenburg, A. M.; Pieterse, G.; Gerbig, C.; Krol, M. C.; Röckmann, T.

    2013-09-01

    In this study, we identify a biomass-burning signal in molecular hydrogen (H2) over the Amazonian tropical rainforest. To quantify this signal, we measure the mixing ratios of H2 and several other species as well as the H2 isotopic composition in air samples that were collected in the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) aircraft campaign during the dry season. We derive a relative H2 emission ratio with respect to carbon monoxide (CO) of 0.31 ± 0.04 ppb ppb-1 and an isotopic source signature of -280 ± 41‰ in the air masses influenced by tropical biomass burning. In order to retrieve a clear source signal that is not influenced by the soil uptake of H2, we exclude samples from the atmospheric boundary layer. This procedure is supported by data from a global chemistry transport model. The ΔH2 / ΔCO emission ratio is significantly lower than some earlier estimates for the tropical rainforest. In addition, our results confirm the lower values of the previously conflicting estimates of the H2 isotopic source signature from biomass burning. These values for the emission ratio and isotopic source signatures of H2 from tropical biomass burning can be used in future bottom-up and top-down approaches aiming to constrain the strength of the biomass-burning source for H2. Hitherto, these two quantities relied only on combustion experiments or on statistical relations, since no direct signal had been obtained from in-situ observations.

  18. Emission ratio and isotopic signatures of molecular hydrogen emissions from tropical biomass burning

    Directory of Open Access Journals (Sweden)

    F. A. Haumann

    2013-09-01

    Full Text Available In this study, we identify a biomass-burning signal in molecular hydrogen (H2 over the Amazonian tropical rainforest. To quantify this signal, we measure the mixing ratios of H2 and several other species as well as the H2 isotopic composition in air samples that were collected in the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia aircraft campaign during the dry season. We derive a relative H2 emission ratio with respect to carbon monoxide (CO of 0.31 ± 0.04 ppb ppb−1 and an isotopic source signature of −280 ± 41‰ in the air masses influenced by tropical biomass burning. In order to retrieve a clear source signal that is not influenced by the soil uptake of H2, we exclude samples from the atmospheric boundary layer. This procedure is supported by data from a global chemistry transport model. The ΔH2 / ΔCO emission ratio is significantly lower than some earlier estimates for the tropical rainforest. In addition, our results confirm the lower values of the previously conflicting estimates of the H2 isotopic source signature from biomass burning. These values for the emission ratio and isotopic source signatures of H2 from tropical biomass burning can be used in future bottom-up and top-down approaches aiming to constrain the strength of the biomass-burning source for H2. Hitherto, these two quantities relied only on combustion experiments or on statistical relations, since no direct signal had been obtained from in-situ observations.

  19. Emission ratio and isotopic signatures of molecular hydrogen emissions from tropical biomass burning

    Directory of Open Access Journals (Sweden)

    F. A. Haumann

    2013-04-01

    Full Text Available In this study, we identify a biomass-burning signal in molecular hydrogen (H2 over the Amazonian tropical rainforest. To quantify this signal, we measure the mixing ratios of H2 and several other species as well as the H2 isotopic composition in air samples that were collected in the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia aircraft campaign during the dry season. We derive a relative H2 emission ratio with respect to carbon monoxide (CO of 0.31 ± 0.04 ppb/ppb and an isotopic source signature of −280 ± 41‰ in the air masses influenced by tropical biomass burning. In order to retrieve a clear source signal that is not influenced by the soil uptake of H2, we exclude samples from the atmospheric boundary layer. This procedure is supported by data from a global chemistry transport model. The ΔH2/ΔCO emission ratio is significantly lower than some earlier estimates for the tropical rainforest. In addition, our results confirm the lower values of the previously conflicting estimates of the H2 isotopic source signature from biomass burning. These values for the emission ratio and isotopic source signatures of H2 from tropical biomass burning can be used in future bottom-up and top-down approaches aiming to constrain the strength of the biomass-burning source for H2. Hitherto, these two quantities relied only on combustion experiments or on statistical relations, since no direct signal had been obtained from in-situ observations.

  20. Strontium isotopes in carbonate deposits at Crater Flat, Nevada

    International Nuclear Information System (INIS)

    Strontium isotope studies of carbonates from soils, veins, eolian dust and Paleozoic basement samples near Crater Flat, southwest of Yucca Mountain, provide evidence for the origins of these materials. Vein and soil carbonates have nearly identical ranges of 87Sr/86Sr ratios at the lower end of the pedogenic range. The average 87Sr/86Sr of Paleozoic basement from Black Marble Hill is similar to the 87Sr/86Sr in the eolian dust, perhaps indicating a local source for this material. Possible spring deposits have generally higher 87Sr/86Sr than the other carbonates. These data are compared with similar data from areas east of Yucca Mountain. 7 refs., 5 figs

  1. Boron isotope ratios of surface waters in Guadeloupe, Lesser Antilles

    Energy Technology Data Exchange (ETDEWEB)

    Louvat, Pascale, E-mail: louvat@ipgp.fr [Geochimie et Cosmochimie, IPGP, Universite Paris Diderot, Sorbonne Paris Cite, UMR 7154 CNRS, 75005 Paris (France); Gaillardet, Jerome; Paris, Guillaume; Dessert, Celine [Geochimie et Cosmochimie, IPGP, Universite Paris Diderot, Sorbonne Paris Cite, UMR 7154 CNRS, 75005 Paris (France)

    2011-06-15

    Highlights: > Rivers outer of hydrothermal areas have d11B around 40 per mille and [B] of 10-31 {mu}g/L. > Thermal springs have d11B of 8-15 per mille and [B] between 250 and 1000 {mu}g/L. > With Na, SO{sub 4} and Cl, boron shows mixing of rain, low and high-T weathering inputs. > Guadeloupe rivers and thermal springs have d11B 20-40 per mille higher than the local rocks. > Solid-solution fractionation during weathering pathways may explain this gap of d11B. - Abstract: Large variations are reported in the B concentrations and isotopic ratios of river and thermal spring waters in Guadeloupe, Lesser Antilles. Rivers have {delta}{sup 11}B values around 40 per mille and B concentrations lower than 30 {mu}g/L, while thermal springs have {delta}{sup 11}B of 8-15 per mille and B concentrations of 250-1000 {mu}g/L. River samples strongly impacted by hydrothermal inputs have intermediate {delta}{sup 11}B and B contents. None of these surface water samples have {delta}{sup 11}B comparable to the local unweathered volcanic rocks (around 0 per mille), implying that a huge isotopic fractionation of 40 per mille takes place during rock weathering, which could be explained by preferential incorporation of {sup 10}B during secondary mineral formation and adsorption on clays, during rock weathering or in the soils. The soil-vegetation B cycle could also be a cause for such a fractionation. Atmospheric B with {delta}{sup 11}B of 45 per mille represents 25-95% of the river B content. The variety of the thermal spring chemical composition renders the understanding of B behavior in Guadeloupe hydrothermal system quite difficult. Complementary geochemical tracers would be helpful.

  2. Carbon isotopes in terrestrial ecosystem pools and CO2 fluxes.

    OpenAIRE

    Bowling, DR; Pataki, DE; Randerson, JT

    2008-01-01

    Stable carbon isotopes are used extensively to examine physiological, ecological, and biogeochemical processes related to ecosystem, regional, and global carbon cycles and provide information at a variety of temporal and spatial scales. Much is known about the processes that regulate the carbon isotopic composition (delta(13)C) of leaf, plant, and ecosystem carbon pools and of photosynthetic and respiratory carbon dioxide (CO(2)) fluxes. In this review, systematic patterns and mechanisms unde...

  3. Molybdenum isotopic composition of modern and Carboniferous carbonates

    OpenAIRE

    Voegelin, Andrea R.; Nägler, Thomas F.; Samankassou, Elias; Villa, Igor M.

    2009-01-01

    We investigate the redox-sensitive isotope system of molybdenum (Mo) in marine carbonates to evaluate their potential as archive of the Mo isotopic composition of coeval seawater. We present Mo isotope data (δ98/95Mo) of modern skeletal and non-skeletal carbonates as well as a variety of precipitates from the mid and late Carboniferous. The external reproducibility is determined by repeated analyses of two commercially available carbonate standards. The resulting uncertainty of the low concen...

  4. Detailed assessment of isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters.

    Science.gov (United States)

    Zhao, Liangju; Xiao, Honglang; Zhou, Jian; Wang, Lixin; Cheng, Guodong; Zhou, Maoxian; Yin, Li; McCabe, Matthew F

    2011-10-30

    As an alternative to isotope ratio mass spectrometry (IRMS), the isotope ratio infrared spectroscopy (IRIS) approach has the advantage of low cost, continuous measurement and the capacity for field-based application for the analysis of the stable isotopes of water. Recent studies have indicated that there are potential issues of organic contamination of the spectral signal in the IRIS method, resulting in incorrect results for leaf samples. To gain a more thorough understanding of the effects of sample type (e.g., leaf, root, stem and soil), sample species, sampling time and climatic condition (dry vs. wet) on water isotope estimates using IRIS, we collected soil samples and plant components from a number of major species at a fine temporal resolution (every 2 h for 24-48 h) across three locations with different climatic conditions in the Heihe River Basin, China. The hydrogen and oxygen isotopic compositions of the extracted water from these samples were measured using both an IRMS and an IRIS instrument. The results show that the mean discrepancies between the IRMS and IRIS approaches for δ(18) O and δD, respectively, were: -5.6‰ and -75.7‰ for leaf water; -4.0‰ and -23.3‰ for stem water; -3.4‰ and -28.2‰ for root water; -0.5‰ and -6.7‰ for xylem water; -0.06‰ and -0.3‰ for xylem flow; and -0.1‰ and 0.3‰ for soil water. The order of the discrepancy was: leaf > stem ≈ root > xylem > xylem flow ≈ soil. In general, species of the same functional types (e.g., woody vs. herbaceous) within similar habitats showed similar deviations. For different functional types, the differences were large. Sampling at nighttime did not remove the observed deviations. PMID:21953962

  5. Detailed assessment of isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters

    Science.gov (United States)

    Zhao, L.; Xiao, H.; Zhou, J.; Wang, L.; Cheng, G.; Zhou, M.; Yin, L.; McCabe, M. F.

    2011-12-01

    As an alternative to isotope ratio mass spectrometry (IRMS) the isotope ratio infrared spectroscopy (IRIS) approach has the advantage of low cost, continuous measurement and capacity for field based application for the analysis of stable water isotopes. Recent studies have indicated that there are potential issues of organic contamination of the spectral signal in the IRIS method, resulting in errant readings for leaf samples. To gain a more thorough understanding of the effects of sample type (e.g., leaf, root, stem and soil), sample species, sampling time and climatic condition (dry vs. wet) on water isotope estimates using IRIS, we collected soil samples and plant components from a number of major species at a fine temporal resolution (every two hours for 24-48 hours) across three locations with different climatic conditions in the Heihe River Basin, China. The hydrogen and oxygen isotopic composition of the extracted water from these samples was measured using both an IRMS and IRIS instrument. Results show that the mean discrepancy between the IRMS and IRIS approach, for δ18O and δD respectively, was: -5.6% and -75.7% for leaf water; -4.0% and -23.3% for stem water; -3.4% and -28.2% for root water; -6.7% and -0.5% for xylem water; -0.06% and -0.3% for xylem flow; and -0.1% and 0.3% for soil water. The order of the discrepancy followed: leaf > stem ≈ root > xylem > xylem flow ≈ soil. In general, species of the same functional types (e.g., woody vs. herbaceous) within similar habitats showed similar deviations. For different functional types, the differences were large. Sampling during the nighttime did not remove the observed deviations.

  6. Can stable isotope ratios provide for community-wide measures of trophic structure?

    Science.gov (United States)

    Layman, Craig A; Arrington, D Albrey; Montaña, Carmen G; Post, David M

    2007-01-01

    Stable isotope ratios (typically of carbon and nitrogen) provide one representation of an organism's trophic niche and are widely used to examine aspects of food web structure. Yet stable isotopes have not been applied to quantitatively characterize community-wide aspects of trophic structure (i.e., at the level of an entire food web). We propose quantitative metrics that can be used to this end, drawing on similar approaches from ecomorphology research. For example, the convex hull area occupied by species in delta13C-delta15N niche space is a representation of the total extent of trophic diversity within a food web, whereas mean nearest neighbor distance among all species pairs is a measure of species packing within trophic niche space. To facilitate discussion of opportunities and limitations of the metrics, we provide empirical and conceptual examples drawn from Bahamian tidal creek food webs. These examples illustrate how this methodology can be used to quantify trophic diversity and trophic redundancy in food webs, as well as to link individual species to characteristics of the food web in which they are embedded. Building from extensive applications of stable isotope ratios by ecologists, the community-wide metrics may provide a new perspective on food web structure, function, and dynamics. PMID:17489452

  7. Variations in the 13C/12C isotopic ratio in the animal metabolism

    International Nuclear Information System (INIS)

    Following the work undertaken by Duchesne et al., a synthesis of the results obtained since 1968 is presented. Differences up to 10 per mil are observed in the isotopic ratio 13C/12C of the CO2 exhaled by various animals as a function of their diet and especially of the presence in their diet of vegetables characterized by a C4 photosynehetic pathway (such as maize). Weak but significant variations of the CO2 isotopic ratio are also observed during starvation, after injection of hormones which regulate the glycaemia or even simply in relation to the metabolic rhythms of normal digestion; these variations seem to be correlated with the modifications arising in the relative proportion of substrates from which carbon dioxide is formed. Small isotopic fractionations, appearing mainly in bones and fats, were also shown by combustion of various tissues. Moreover, a change in diet (use of corn) affects clearly, not only the exhaled CO2, but also, within a few days, the mean 13C content of organs, mainly in the case of the liver. These metabolic fractionations remain, however, limited enough to use the 13C content, naturally a little higher, of C4 photosynthetic vegetables as a tracer in order to follow some metabolic processes. An application of this is presented by way of a flucose tolerance test

  8. [Effects of lipid extraction on stable carbon and nitrogen isotope analyses of Ommastrephes bartramii muscle].

    Science.gov (United States)

    Gong, Yi; Chen, Xin-Jun; Gao, Chun-Xia; Li, Yun-Kai

    2014-11-01

    Stable isotope analysis (SIA) has become an important tool to investigate diet shift, habitat use and trophic structure of animal population. Muscle is considered to be the most common tissue for SIA, however, lipid content in muscle causes a considerable bias to the interpretation of isotopic ratios of animals. Neon flying squid (Ommastrephes bartramii) is an important economic cephalopod of Chinese distant water fishery, and plays a major role in marine ecosystems. In this study, the effects of lipid extraction on stable isotope ratios of the muscles of 53 neon flying squids were investigated and the interference mechanism of lipid in SIA was clarified with the aim of contrasting the suitability of different lipid correction models of stable carbon isotope. Results showed that the stable carbon and nitrogen isotopic values of non-lipid extracted samples significantly increased after lipid extractions by 0.71 per thousand and 0.47 per thousand, respectively, which suggested that lipid extraction in cephalopod isotope study is needed prior to stable carbon isotope analysis but not recommended for stable nitrogen isotope analysis. The results could help remove the effects of lipid contents and standardize SIA muscle samples, thereby getting better understanding of the isotopic change of neon flying squids in the future. PMID:25898636

  9. High precision Faraday collector MC-ICPMS thorium isotope ratio determination

    Science.gov (United States)

    Potter, Emma-Kate; Stirling, Claudine H.; Andersen, Morten B.; Halliday, Alex N.

    2005-12-01

    Uranium-series dating of carbonate materials requires precise determination of the spike sample thorium isotope ratio, 230Th/229Th. This ratio is commonly measured using ion counting techniques, however the precision of analyses using ion counting devices suffers from beam intensity limitations, drift in multiplier gain and non-linearities in electron multiplier response. Here, we describe the application of multiple-collector inductively coupled plasma mass spectrometry (MC-ICPMS) to determine thorium isotope ratios at hitherto unattained precision. For the first time, thorium isotope analyses were performed using only Faraday collectors coupled to 1011 [Omega] feedback resistors in the amplifier system. Spiked thorium solutions were concentrated to produce 230Th and 229Th signal intensities of around 50 mV and 100 mV, respectively (across a 1011 [Omega] resistor) and are run at high intensity for a short period of time (~1 min). These analyses yield a 230Th/229Th external reproducibility of better than 0.3[per mille sign] for ~25-30 pg of consumed 230Th. This is a factor of two better than the best published thermal ionisation mass spectrometry (TIMS) and MC-ICPMS techniques for similar sample sizes, and represents up to an order of magnitude improvement over many other established protocols. Combined with new techniques for high precision Faraday measurement of uranium isotopic composition [1], this permits improvements in the uncertainty of U-series ages to better than 0.1 thousand years (ka) at 100 ka and 1 ka at 300 ka. It should also be possible to resolve events to ~14 ka at 600 ka. Using these techniques, the U-series dating limit can be extended from 500-600 ka to 800 ka enabling a more detailed study of the frequency of late Pleistocene climate events.

  10. Carbon and Oxygen isotopic composition in paleoenvironmental determination

    International Nuclear Information System (INIS)

    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 O16 than the patterns from marine environments. The C12 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.)

  11. Comparison of water isotope analysis between cavity ring-down spectroscopy and isotope ratio mass spectrometry

    International Nuclear Information System (INIS)

    δD and δ18O of natural waters with δ18O ranging from -24 to -6‰ were measured using a cavity ring-down spectroscopy (CRDS) in order to confirm that the CRDS method can be an alternative to conventional isotope ratio mass spectrometry (IRMS). The deviations of δD and δ18O values obtained using the CRDS and IRMS methods are less than 0.8‰ and 0.3‰, respectively, which are practically sufficient for geochemical/environmental researches of natural waters, indicating that the CRDS method can be an alternative to the IRMS methods for environmental liquid water samples. (author)

  12. Development, optimisation, and application of ICP-SFMS methods for the measurement of isotope ratios

    Energy Technology Data Exchange (ETDEWEB)

    Stuerup, S

    2000-07-01

    The measurement of isotopic composition and isotope ratios in biological and environmental samples requires sensitive, precise, and accurate analytical techniques. The analytical techniques used are traditionally based on mass spectrometry, among these techniques is the ICP-SFMS technique, which became commercially available in the mid 1990s. This technique is characterised by high sensitivity, low background, and the ability to separate analyte signals from spectral interferences. These features are beneficial for the measurement of isotope ratios and enable the measurement of isotope ratios of elements, which it has not previously been possible to measure due to either spectral interferences or poor sensitivity. The overall purpose of the project was to investigate the potential of the single detector ICP-SFMS technique for the measurement of isotope ratios in biological and environmental samples. One part of the work has focused on the fundamental aspects of the ICP-SFMS technique with special emphasize on the features important to the measurement of isotope ratios, while another part has focused on the development, optimisation and application of specific methods for the measurement of isotope ratios of elements of nutritional interest and radionuclides. The fundamental aspects of the ICP-SFMS technique were investigated theoretically and experimentally by the measurement of isotope ratios applying different experimental conditions. It was demonstrated that isotope ratios could be measured reliably using ICP-SFMS by educated choice of acquisition parameters, scanning mode, mass discrimination correction, and by eliminating the influence of detector dead time. Applying the knowledge gained through the fundamental study, ICP-SFMS methods for the measurement of isotope ratios of calcium, zinc, molybdenum and iron in human samples and a method for the measurement of plutonium isotope ratios and ultratrace levels of plutonium and neptunium in environmental samples

  13. Development, optimisation, and application of ICP-SFMS methods for the measurement of isotope ratios

    International Nuclear Information System (INIS)

    The measurement of isotopic composition and isotope ratios in biological and environmental samples requires sensitive, precise, and accurate analytical techniques. The analytical techniques used are traditionally based on mass spectrometry, among these techniques is the ICP-SFMS technique, which became commercially available in the mid 1990s. This technique is characterised by high sensitivity, low background, and the ability to separate analyte signals from spectral interferences. These features are beneficial for the measurement of isotope ratios and enable the measurement of isotope ratios of elements, which it has not previously been possible to measure due to either spectral interferences or poor sensitivity. The overall purpose of the project was to investigate the potential of the single detector ICP-SFMS technique for the measurement of isotope ratios in biological and environmental samples. One part of the work has focused on the fundamental aspects of the ICP-SFMS technique with special emphasize on the features important to the measurement of isotope ratios, while another part has focused on the development, optimisation and application of specific methods for the measurement of isotope ratios of elements of nutritional interest and radionuclides. The fundamental aspects of the ICP-SFMS technique were investigated theoretically and experimentally by the measurement of isotope ratios applying different experimental conditions. It was demonstrated that isotope ratios could be measured reliably using ICP-SFMS by educated choice of acquisition parameters, scanning mode, mass discrimination correction, and by eliminating the influence of detector dead time. Applying the knowledge gained through the fundamental study, ICP-SFMS methods for the measurement of isotope ratios of calcium, zinc, molybdenum and iron in human samples and a method for the measurement of plutonium isotope ratios and ultratrace levels of plutonium and neptunium in environmental samples

  14. Carbon Isotopic Fractionation During Formation of Macromolecular Organic Grain Coatings via FTT Reactions

    Science.gov (United States)

    Nuth, J. A.; Johnson, N. M.; Elsila-Cook, J.; Kopstein, M.

    2011-01-01

    Observations of carbon isotopic fractionation of various organic compounds found in meteorites may provide useful diagnostic information concerning the environments and mechanisms that were responsible for their formation. Unfortunately, carbon has only two stable isotopes, making interpretation of such observations quite problematic. Chemical reactions can increase or decrease the C-13/C-12 ratio by various amounts, but the final ratio will depend on the total reaction pathway followed from the source carbon to the final product, a path not readily discernable after 4.5 billion years. In 1970 Libby showed that the C-13/C-12 ratios of terrestrial and meteoritic carbon were similar by comparing carbon from the Murchison meteorite to that of terrestrial sediments. More recent studies have shown that the C-13/C-12 ratio of the Earth and meteorites may be considerably enriched in C-13 compared to the ratio observed in the solar wind [2], possibly suggesting that carbon produced via ion-molecule reactions in cold dark clouds could be an important source of terrestrial and meteoritic carbon. However, meteoritic carbon has been subjected to parent body processing that could have resulted in significant changes to the C-13/C-12 ratio originally present while significant variation has been observed in the C-13/C-12 ratio of the same molecule extracted from different terrestrial sources. Again we must conclude that understanding the ratio found in meteorites may be difficult.

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

    International Nuclear Information System (INIS)

    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 δ13C, δ18O and Δ17O 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 13CO/12CO 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 13C methane oxidation source. In particular, a high average yield of 0.94 CO per reacted methane (CH4) molecule is simulated in the troposphere, to a large extent due to the competition between the deposition and convective transport processes affecting the CH4 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 13C, were found significant when explicitly simulated. The inaccurate surface

  16. Carbon isotope fractionation in synthetic magnesian calcite

    Science.gov (United States)

    Jimenez-Lopez, Concepción; Romanek, Christopher S.; Caballero, Emilia

    2006-03-01

    Mg-calcite was precipitated at 25 °C in closed system, free-drift experiments, from solutions containing NaHCO 3, CaCl 2 and MgCl 2. The carbon stable isotope composition of bulk solid and solution were analyzed from subsamples collected during time course experiments of 24 h duration. Considering only the Mg-content and δ 13C values for the bulk solid, the carbon isotope fractionation factor for the Mg-calcite-HCO 3(aq)- system (as 103lnα) increased with average mol percentage of Mg (X Mg) in the solid at a rate of (0.024 ± 0.011) per mol% MgCO 3. Extrapolation of this relationship to the pure calcite end member yields a value of 0.82 ± 0.09, which is similar to published values for the calcite-HCO 3(aq)- system. Although 103lnα did not vary for precipitation rates that ranged from 10 3.21 to 10 4.60 μmol m -2 h -1, it was not possible to hold Mg-content of the solid constant, so kinetic effect on 10 3 ln α could not be evaluated from these experiments.

  17. Carbon isotope analysis in apple nectar beverages

    Directory of Open Access Journals (Sweden)

    Ricardo Figueira

    2013-03-01

    Full Text Available The aims of this study were to use the isotope analysis method to quantify the carbon of C3 photosynthetic cycle in commercial apple nectars and to determine the legal limit to identify the beverages that do not conform to the safety standards established by the Brazilian Ministry of Agriculture, Livestock and Food Supply. These beverages (apple nectars were produced in the laboratory according to the Brazilian legislation. Adulterated nectars were also produced with an amount of pulp juice below the permitted threshold limit value. The δ13C values of the apple nectars and their fractions (pulp and purified sugar were measured to quantify the C3 source percentage. In order to demonstrate the existence of adulteration, the values found were compared to the limit values established by the Brazilian Law. All commercial apple nectars analyzed were within the legal limits, which enabled to identify the nectars that were in conformity with the Brazilian Law. The isotopic methodology developed proved efficient to quantify the carbon of C3 origin in commercial apple nectars.

  18. Discrepancies between isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters.

    Science.gov (United States)

    West, Adam G; Goldsmith, Gregory R; Brooks, Paul D; Dawson, Todd E

    2010-07-30

    The use of isotope ratio infrared spectroscopy (IRIS) for the stable hydrogen and oxygen isotope analysis of water is increasing. While IRIS has many advantages over traditional isotope ratio mass spectrometry (IRMS), it may also be prone to errors that do not impact upon IRMS analyses. Of particular concern is the potential for contaminants in the water sample to interfere with the spectroscopy, thus leading to erroneous stable isotope data. Water extracted from plant and soil samples may often contain organic contaminants. The extent to which contaminants may interfere with IRIS and thus impact upon data quality is presently unknown. We tested the performance of IRIS relative to IRMS for water extracted from 11 plant species and one organic soil horizon. IRIS deviated considerably from IRMS for over half of the samples tested, with deviations as large as 46 per thousand (delta(2)H) and 15.4 per thousand (delta(18)O) being measured. This effect was reduced somewhat by using activated charcoal to remove organics from the water; however, deviations as large as 35 per thousand (delta(2)H) and 11.8 per thousand (delta(18)O) were still measured for these cleaned samples. Interestingly, the use of activated charcoal to clean water samples had less effect than previously thought for IRMS analyses. Our data show that extreme caution is required when using IRIS to analyse water samples that may contain organic contaminants. We suggest that the development of new cleaning techniques for removing organic contaminants together with instrument-based software to flag potentially problematic samples are necessary to ensure accurate plant and soil water analyses using IRIS. PMID:20552579

  19. Isotope analysis of carbon monoxide in atmospheric samples

    International Nuclear Information System (INIS)

    A technique was established that allows the analysis of carbon and oxygen isotope composition of CO in small air samples (250ml). The method is based on the oxidation of CO to CO2 with iodine pentoxide and the subsequent isotope analysis of CO2. Potential applications include the use of CO and its isotopes as a tracer to distinguish different pollution sources. (author)

  20. Stable Isotope Measurements of Carbon Dioxide, Methane, and Hydrogen Sulfide Gas Using Frequency Modulation Spectroscopy

    Science.gov (United States)

    Nowak-Lovato, K.

    2014-12-01

    Seepage from enhanced oil recovery, carbon storage, and natural gas sites can emit trace gases such as carbon dioxide, methane, and hydrogen sulfide. Trace gas emission at these locations demonstrate unique light stable isotope signatures that provide information to enable source identification of the material. Light stable isotope detection through surface monitoring, offers the ability to distinguish between trace gases emitted from sources such as, biological (fertilizers and wastes), mineral (coal or seams), or liquid organic systems (oil and gas reservoirs). To make light stable isotope measurements, we employ the ultra-sensitive technique, frequency modulation spectroscopy (FMS). FMS is an absorption technique with sensitivity enhancements approximately 100-1000x more than standard absorption spectroscopy with the advantage of providing stable isotope signature information. We have developed an integrated in situ (point source) system that measures carbon dioxide, methane and hydrogen sulfide with isotopic resolution and enhanced sensitivity. The in situ instrument involves the continuous collection of air and records the stable isotope ratio for the gas being detected. We have included in-line flask collection points to obtain gas samples for validation of isotopic concentrations using our in-house isotope ratio mass spectroscopy (IRMS). We present calibration curves for each species addressed above to demonstrate the sensitivity and accuracy of the system. We also show field deployment data demonstrating the capabilities of the system in making live dynamic measurements from an active source.

  1. Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry

    Science.gov (United States)

    Merritt, D. A.; Freeman, K. H.; Ricci, M. P.; Studley, S. A.; Hayes, J. M.

    1995-01-01

    Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T CuO at 850 degrees C, NiO + O2 (gas-phase mole fraction, 10(-3)) at 1050 degrees C and NiO at 1150 degrees C. The combustion interface did not contribute additional analytical uncertainty, thus observed standard deviations of 13C/12C ratios were within a factor of 2 of shot-noise limits. For combustion and isotopic analyses of CH4, in which quantitative combustion required T approximately 950 degrees C, NiO-based systems are preferred, and precision is approximately 2 times lower than that observed for other analytes. Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer.

  2. Automatic isotope ratio measurements with a double collector magnetic mass spectrometer

    International Nuclear Information System (INIS)

    This paper describes a measuring procedure and the instrumentation of automatic measurements of isotope ratios with double collector magnetic mass spectrometers. This is essentially achieved by discriminating the desired peak plateau for ion current integration during the high voltage variation. The resolution is nearly uneffected by offset drifts of the electronic system. Prior to every isotope ratio measurement the offset values are determined, digitally stored, and finally compensated when the isotope ratio is calculated with an arithmetic unit. Several mass spectrometers have been compared on the basis of an uranium isotope analysis in a long time experiment. The developed system proved reliable and showed the same resolution as more sophisticated spectrometer systems. (orig.)

  3. Systematic AMD+GCM Study of Structure of Carbon Isotopes

    International Nuclear Information System (INIS)

    The structure of low-lying states of the carbon isotopes is investigated using the extended version of the Antisymmetrized Molecular Dynamics (AMD) Multi-Slater Determinant model. We can reproduce reasonably well many experimental data for carbon isotopes 12C-22C. A special approach is adopted for 15C to better describe the tail of the wave function

  4. Development of a system for determination of the 13C/12C isotopic ratio with high spatial resolution

    International Nuclear Information System (INIS)

    Stable carbon isotopes play an important role in the interpretation of biological activity, particularly when the fossil record is studied. In combination with morphological and chemical data, isotopic information can be useful in paleontology and astrobiology. In this paper the development of a microanalytical ion beam system for the measurement of the carbon isotope ratio with high spatial resolution and good statistics is presented. The technique used is elastic scattering of alpha particles with an energy of 2.75 MeV. At this energy the 13C cross-section is enhanced relative to the Rutherford cross-section and while the 12C cross-section is reduced. The optimisation of the system is described, including sample preparation and the design of the particle detection system for high efficiency combined with good energy resolution. Finally, some results from the initial test run of the system are shown and discussed

  5. Stable isotope ratio determination of the origin of vanillin in vanilla extracts and its relationship to vanillin/potassium ratios

    International Nuclear Information System (INIS)

    A method is described for isolating vanillin from vanilla extract, followed by stable isotope ratio analysis to determine the amount of natural vanillin contained in adulterated vanilla extracts. After the potassium content is determined, the percent Madagascar and/or Java vanilla beans incorporated into the extract may then be approximated from the vanillin/potassium ratio

  6. Dynamical and Microphysical Controls on Subtropical Water Vapor Isotope Ratios: Using New Spectroscopic Measurements to Link Isotopic and Climatic Variability

    Science.gov (United States)

    Raudzens Bailey, A.; Nusbaumer, J. M.; Sato, P.; Noone, D. C.

    2014-12-01

    Water vapor isotope ratios are critical in shaping the isotopic composition of paleo-proxies used to interpret past climate. Indeed, previous research suggests speleothems are sensitive to water vapor transport, and experiments currently underway are evaluating the role of Greenlandic vapor in setting the isotopic record of the ice sheet. The recent and rapid spread of commercial vapor isotopic analyzers—based on cavity-enhanced near-infrared laser absorption spectroscopy—is creating unparalleled opportunities to elucidate which climatic factors control the vapor isotopic composition globally. This presentation describes both an exciting application of this new technology and relevant limitations imposed by measurement uncertainties associated with long-term field deployments. Using three years of continuous water vapor isotope ratio observations from Hawaii's Mauna Loa Observatory—one of the longest records of its kind—we evaluate the influence of large-scale dynamics and cloud microphysical processes in establishing the isotopic composition of water vapor during strong convective activity. Despite the fact that vapor isotope ratios tend to decrease with latitude, greater enrichment in Mauna Loa vapor is associated with a westward retraction of the jet stream, which funnels Asiatic outflow southward, while greater depletion is associated with southwesterly low-level flow. Differences in precipitation efficiency—which are verified by differences in aerosol concentration and total scattering—cause this apparent discrepancy. These results suggest local cloud and precipitation processes are more influential than airmass origin in setting the isotope ratios observed during these strong convective events. The length of the Mauna Loa record, meanwhile, presents a unique opportunity to evaluate long-term stability of biases associated with laser-based isotopic analyzers and to discuss calibration strategies best suited for monitoring programs designed to

  7. Maintaining high precision of isotope ratio analysis over extended periods of time

    International Nuclear Information System (INIS)

    Full text: The measurement of stable isotope ratios from natural material often requires a very high precision. This is especially true when the isotopic signatures in question are small, e.g. when - studying water stress in plants through investigation of δ13C in tree rings (up to 3 per mille variation); - following the addition of fossil carbon in atmospheric CO2 (increase of 0.025 per mille/year); - investigating δ18O or δD of water in ice cores in order to reconstruct climatic change in the past (1-2 per mille and 20-40 per mille respectively). In order to maintain such high precision over extended periods of time we have installed a rigorous quality control of isotopic measurements in our isotope laboratory. The most important guideline for establishing such a scheme is to understand the measurement process in great detail and to treat samples and reference material in a closely identical fashion. For examples tree ring isotopes are determined in a Laser Ablation experiment where the sample material is ablated and transported to combustion furnace for conversion to CO2. In the same chamber, we include cellulose as an internal reference. In between sample ablation shots we hit the cellulose and use the resulting CO2 for scale correction. δ13C analysis of CO2 in air samples from around the globe is based on whole air standards measured on the same multi-sample carousel on a daily basis. External precision of 0.013 per mille has been maintained over a record of the last four years, monitored through a daily measurement of a quality control air through the same inlet line. Water isotopic analysis is made using injection of plain water into a high temperature (>1400 deg. C) reactor filled with (glassy) carbon using a gas tight syringe. The precision for both, 18O and D/H is monitored by injecting local reference water samples interspersed with the normal sample water. Examples of the techniques and the associated QA scheme will be presented and discussed

  8. Intra-Shell boron isotope ratios in benthic foraminifera: Implications for paleo-pH reconstructions

    Science.gov (United States)

    Rollion-Bard, C.; Erez, J.

    2009-12-01

    The boron isotope composition of marine carbonates is considered to be a seawater pH proxy. Nevertheless, the use of δ11B has some limitations: 1) the knowledge of fractionation factor (α4-3) between the two boron dissolved species (boric acid and borate ion), 2) the δ11B of seawater may have varied with time and 3) the amplitude of the "vital effects" of this proxy. Using secondary ion mass spectrometry (SIMS), we looked at the internal variability in the boron isotope ratio of the shallow water, symbionts bearing foraminiferan Amphistegina lobifera. Specimens were cultured at constant temperature (24±0.1 °C) in seawater with pH ranging between 7.90 and 8.45. We performed 6 to 8 measurements of δ11B in each foraminifera. Intra-shell boron isotopes show large variability with an upper threshold value of pH ~ 9. The ranges of the skeletal calculated pH values in different cultured foraminifera, show strong correlation with the culture pH values and may thus serve as proxy for pH in the past ocean.

  9. Liquid and gas chromatography coupled to isotope ratio mass spectrometry for the determination of 13C-valine isotopic ratios in complex biological samples.

    Science.gov (United States)

    Godin, Jean-Philippe; Breuillé, Denis; Obled, Christiane; Papet, Isabelle; Schierbeek, Henk; Hopfgartner, Gérard; Fay, Laurent-Bernard

    2008-10-01

    On-line gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is commonly used to measure isotopic ratios at natural abundance as well as for tracer studies in nutritional and medical research. However, high-precision (13)C isotopic enrichment can also be measured by liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Indeed, LC-IRMS can be used, as shown by the new method reported here, to obtain a baseline separation and to measure (13)C isotopic enrichment of underivatised amino acids (Asp, Thr-Ser, Glu, Pro, Gly, Ala, Cys and Val). In case of Val, at natural abundance, the SD(delta(13)C) reported with this method was found to be below 1 per thousand . Another key feature of the new LC-IRMS method reported in this paper is the comparison of the LC-IRMS approach with the conventional GC-C-IRMS determination. To perform this comparative study, isotopic enrichments were measured from underivatised Val and its N(O, S)-ethoxycarbonyl ethyl ester derivative. Between 0.0 and 1.0 molar percent excess (MPE) (delta(13)C= -12.3 to 150.8 per thousand), the calculated root-mean-square (rms) of SD was 0.38 and 0.46 per thousand and the calculated rms of accuracy was 0.023 and 0.005 MPE, respectively, for GC-C-IRMS and LC-IRMS. Both systems measured accurately low isotopic enrichments (0.002 atom percent excess (APE)) with an SD (APE) of 0.0004. To correlate the relative (delta(13)C) and absolute (atom%, APE and MPE) isotopic enrichment of Val measured by the GC-C-IRMS and LC-IRMS devices, mathematical equations showing the slope and intercept of the curves were established and validated with experimental data between 0.0 to 2.3 MPE. Finally, both GC-C-IRMS and LC-IRMS instruments were also used to assess isotopic enrichment of protein-bound (13)C-Val in tibial epiphysis in a tracer study performed in rats. Isotopic enrichments measured by LC-IRMS and GC-C-IRMS were not statistically different (p>0.05). The results of this work indicate that

  10. Forensic Applications of Light-Element Stable Isotope Ratios of Ricinus communis Seeds and Ricin Preparations

    Energy Technology Data Exchange (ETDEWEB)

    Kreuzer, Helen W.; West, Jason B.; Ehleringer, James

    2013-01-01

    Seeds of the castor plant Ricinus communis, also known as castor beans, are of forensic interest because they are the source of the poison ricin. We have tested whether stable isotope ratios of castor seeds and ricin prepared by various methods can be used as a forensic signature. We collected over 300 castor seed samples from locations around the world and measured the C, N, O, and H stable isotope ratios of the whole seeds, oil, and three types of ricin preparations. Our results demonstrate that N isotope ratios can be used to correlate ricin prepared by any of these methods to source seeds. Further, stable isotope ratios distinguished >99% of crude and purified ricin protein samples in pair-wise comparison tests. Stable isotope ratios therefore constitute a valuable forensic signature for ricin preparations.

  11. Transfer of carbon isotope in human and animal bodies

    International Nuclear Information System (INIS)

    For realistic estimation of internal dose due to 14C released from nuclear facilities, the one compartment model for 14C metabolism in the human body which ICRP recommends may be too simple to be applied, and precise information on metabolism of radioactive nuclides in the human body is essential. In this study, the exhalation rate of carbon from human and livestock animal bodies was investigated using stable carbon isotope 13C. A 13C amount of 200 mg was administered as 13C-labeled rice to 5 human subjects, and 13C ratios in expiration of the subjects were measured during 2 weeks after the administration. From 2 days prior to the administration to the end of the experiment, meals with a slightly controlled 13C ratio of carbon were offered to the subjects to reduce the fluctuation of background 13C ratio in their breath air. The averaged background 13C ratio in expiration among the subjects was -24.7±0.7 per mille before the ingestion of 13C enriched rice. The highest 13C ratio of 73.0±6.6 per mille was observed 350 min after the ingestion. In the temporal changes in 13C ratio in breath air, three components were observed to have decreasing half times of 3.8, 14.4 and 52.8 h, which may indicate the existence of three compartments in carbon metabolism in the human body. In addition, in order to investigate the transfer of 14C from plants to animal milk, which is one of the important pathways for the assessment of radiation dose due to radionuclides, an experiment to measure the excretion rate of carbon from goats which were given 13C labeled feed (1.174 13C atom%), as representative livestock ruminant, was carried out. The 13C ratio of milk was 1.191% when it reached a plateau, whereas the 13C ratio of serum continued to increase during the feeding period. (author)

  12. Recent measurements of 234U/238U isotope ratio in spring waters from the Hadzici area.

    Science.gov (United States)

    Vidic, Alfred; Ilić, Zorana; Benedik, Ljudmila

    2013-06-01

    The Hadzici area has become interesting for investigation since depleted uranium ammunition had been employed in 1995 during the NATO air strike campaign in Bosnia and Herzegovina. The purpose of this study is to determine uranium concentration and (234)U/(238)U activity ratio in the spring waters of this area and to investigate their relationship, as well as spatial variations. The spring water samples were taken at 18 sites in total. For the determination of uranium radioisotopes, radiochemical separation procedure followed by alpha-particle spectrometry was applied. Uranium concentration in analyzed waters range from 0.15 to 1.12 μg/L. Spring waters from carbonate based sediments have a lower uranium concentration of between 0.15 and 0.43 μg/L, in comparison to waters sampled within sandstone-based sediments ranging from 0.53 to 1.12 μg/L. Dissolved uranium shows significant spatial variability and correlation with bedrock type confirmed by Principal Component Analysis and Hierarchical Cluster Analysis. The majority of the analyzed waters have a (234)U/(238)U activity ratio ranging from 1.02 to 1.90, of which half of the results range between 1.02 and 1.16. No apparent depleted uranium (DU) contamination was observed, as (234)U/(238)U activity ratio is dependent on geochemical conditions in the environment. Even though the tested spring waters demonstrate significant variability in uranium concentration, (234)U/(238)U activity ratio and (234)U excess, waters with similar uranium isotopic signatures are observable within the region. The guidelines on the spatial redistribution of dissolved uranium (corresponding to (238)U mass concentration), along with (234)U/(238)U activity ratios were provided by the Inverse Distance Weighting (IDW) method. Waters having similar isotopic signature have been delineated. PMID:23410592

  13. Changes of stable isotopes carbon-13 and nitrogen-15 in different tissues of cattle

    International Nuclear Information System (INIS)

    Stable isotope analysis is a potential tool for tracing food origin. The stable carbon and nitrogen isotope composition in different tissues of two varieties of cattle under the same culture condition were investigated. δ 13C and δ15N values of different defatted muscle and crude fat, cattle tail hair, blood, liver and feed were determined by isotope ratio mass spectrometry, and statistical analysis was carried out. The results showed that stable isotopes of carbon and nitrogen composition was not affected by cattle variety; the δ 13C values between different defatted muscle, blood, liver and cattle hair were not significantly different, but δ 15N value in the liver was much higher than other muscle and the δ 13C values didn't show difference among all the crude fat samples. So these results indicated that isotope fractionation in the various tissue was discrepant. (authors)

  14. Reducing and correcting for contamination of ecosystem water stable isotopes measured by isotope ratio infrared spectroscopy.

    Science.gov (United States)

    Schmidt, Markus; Maseyk, Kadmiel; Lett, Céline; Biron, Philippe; Richard, Patricia; Bariac, Thierry; Seibt, Ulli

    2012-01-30

    Concern exists about the suitability of laser spectroscopic instruments for the measurement of the (18)O/(16)O and (2)H/(1)H values of liquid samples other than pure water. It is possible to derive erroneous isotope values due to optical interference by certain organic compounds, including some commonly present in ecosystem-derived samples such as leaf or soil waters. Here we investigated the reliability of wavelength-scanned cavity ring-down spectroscopy (CRDS) (18)O/(16)O and (2)H/(1)H measurements from a range of ecosystem-derived waters, through comparison with isotope ratio mass spectrometry (IRMS). We tested the residual of the spectral fit S(r) calculated by the CRDS instrument as a means to quantify the difference between the CRDS and IRMS δ-values. There was very good overall agreement between the CRDS and IRMS values for both isotopes, but differences of up to 2.3‰ (δ(18)O values) and 23‰ (δ(2)H values) were observed in leaf water extracts from Citrus limon and Alnus cordata. The S(r) statistic successfully detected contaminated samples. Treatment of Citrus leaf water with activated charcoal reduced, but did not eliminate, δ(2)H(CRDS) - δ(2)H(IRMS) linearly for the tested range of 0-20% charcoal. The effect of distillation temperature on the degree of contamination was large, particularly for δ(2)H values but variable, resulting in positive, negative or no correlation with distillation temperature. S(r) and δ(CRDS) - δ(IRMS) were highly correlated, in particular for δ(2)H values, across the range of samples that we tested, indicating the potential to use this relationship to correct the δ-values of contaminated plant water extracts. We also examined the sensitivity of the CRDS system to changes in the temperature of its operating environment. We found that temperature changes ≥4 °C for δ(18)O values and ≥10 °C for δ(2)H values resulted in errors larger than the CRDS precision for the respective isotopes and advise the use of such

  15. Isotope ratio as a tracer for investigation of anthropogenic sulfur sources

    International Nuclear Information System (INIS)

    This paper presents studies concerned possibility of application of sulfur isotope ratio to investigate the sulfur pollution, coming from coal combustion process. The samples of hard coal and lignite, slag and ashes were taken from power station Kaweczyn and Belchatow to determine sulfur isotope ratio changes in the products of coal combustion process. Additionally, sulfur from outlet gas was absorbed to determine sulfur isotope fractionation in desulfurization process. Sulfate from outlet gases are enriched in light isotope 32S in comparison to coal which was used in power plants. Fractionation of sulfur isotopes between inlet and outlet gases was observed. The stable sulfur compositions of sulfur compounds in industrial origin, present in atmosphere, biosphere, hydrosphere, groundwater, soil ets., may differ from those for natural sources. Sulfur isotope ratio can be treated as an environmental tracer, and may be applied to study the sulfur pollution distribution from coal combustion process, in the environment. (author)

  16. Tunable diode laser spectroscopy of stable isotopic tracers - Detection and measurement of relative abundance of isotopic carbon monoxide

    International Nuclear Information System (INIS)

    A molecular absorption system using a tunable diode laser and a dual path length sample cell for stable isotopic tracer analysis has been developed. The high spectral resolution and power density of the laser allow real-time simultaneous detection of different isotopes with great specificity. And, the matched absorption path length cell simplifies signal processing and improves the accuracy in quantitative measurement by maintaining the same signal to noise ratio for vastly different isotopic concentrations. The principle and operation of the system are described using isotopic oxygen analysis in carbon monoxide as an illustrative example. The method is applicable to any sample that is or can be converted into an infrared active gas. 8 refs.; 4 figs

  17. Progressive extraction method applied to isotopic exchange of carbon-14

    International Nuclear Information System (INIS)

    Isotopic exchange in natural settings is essentially an irreversible process, so that it progresses continuously until there is complete isotopic equilibrium. In soils, this process involves interaction between isotopes in the liquid and solid phases, and complete isotopic equilibrium may take a very long time. Measurements after partial isotopic exchange have been used to characterize the labile fraction of elements in soils. We describe a method to characterize the extent of isotopic exchange, with application here to incorporation of inorganic carbon-14 (14C) into mineral carbonates and organic matter in soils. The procedure uses a continuous addition of extractant, acid, or H2O2in the examples presented here, coupled with sequential sampling. The method has been applied to demonstrate the degree of isotopic exchange in soil. The same strategy could be applied to many other elements, including plant nutrients. (author)

  18. The response of oxygen isotope ratios in precipitation to changes in global atmospheric circulation

    International Nuclear Information System (INIS)

    Full text: Stable isotopes of oxygen and hydrogen present in water are known to undergo fractionation at phase transitions, with heavy isotopes tending to evaporate less readily and to undergo condensation more readily than lighter isotopes. The combination of fractionation processes for a given air parcel therefore produces the known relationships between precipitation amount, surface temperature and the isotopic ratio in precipitation. An additional factor in determining the isotopic ratio is the effect of changes in vapour source region and vapour path due to changes in atmospheric circulation. In order to explore the effect of changes in circulation related to El Nino/Southern Oscillation (ENSO) events, an atmospheric general circulation model fitted with a diagnostic module to predict the stable isotopic ratios of meteoric water (both HDO and H218O) is used to investigate the effect of warm sea surface temperature (SST) anomalies on moisture transport and hence on isotopic ratios in precipitation. Observed isotopic ratios obtained from the Global Network of Isotopes in Precipitation (GNIP) are also correlated with Troup SOI values and compared with the model results. Copyright (1999) Geological Society of Australia

  19. The quality control of fruit juices by using the stable isotope ratios and trace metal elements concentrations

    Science.gov (United States)

    Magdas, D. A.; Dehelean, A.; Puscas, R.; Cristea, G.; Tusa, F.; Voica, C.

    2012-02-01

    In the last years, a growing number of research articles detailing the use of natural abundance light stable isotopes variations and trace metal elements concentration as geographic "tracers" to determine the provenance of food have been published. These investigations exploit the systematic global variations of stable hydrogen, oxygen and carbon isotope ratios in (combination) relation with trace metal element concentrations. The trace metal elements content of plants and also their light stable isotopic ratios are mainly related to the geological and pedoclimatic characteristics of the site of growth. The interpretation of such analysis requires an important number of data for authentic natural juices regarding the same seasonal and regional origin, because the isotopic analysis parameters of fruit juices show remarkable variability depending on climatologically factors. In this work was mesured H, C, O stable isotope ratios and the concentrations of 16 elements (P, K, Mg, Na, Ca, Cu, Cr, Ni, Zn, Pb, Co, As, Cd, Mn, Fe and Hg) from 12 single strength juices. The natural variations that appear due to different environmental and climatic conditions are presented and discussed.

  20. Anomalous lead isotope ratios and provenance of offshore sediments, Gulf of Carpentaria, northern Australia

    International Nuclear Information System (INIS)

    Anomalous Pb isotope ratios measured by Inductively Coupled Plasma Mass Spectrometry in terrigenous marine sediments (208Pb/206Pb and low 207Pb/206Pb. This interpretation is supported by strong correlations between Pb isotope ratio and Th, U and light rare-earth element concentrations in the sediments as well as by monazite compositional data. A likely source of the detrital monazite is the western portion of the Georgetown Inlier of mainly Proterozoic S-type granitic rocks. A clear distinction between Pb isotope ratios in sediments deposited from the Norman and Bynoe Rivers in the southeast Gulf of Carpentaria and the persistence of catchment-specific Pb isotope ratios 45 km offshore suggest that Pb isotope data are useful in tracing the provenance of terrigenous offshore sediments when the source rocks of catchments show sufficient chemical and/or mineralogical variation. Copyright (2000) Geological Society of Australia

  1. Stable isotope ratio measurements in atmospheric sulfate studies

    International Nuclear Information System (INIS)

    The isotopic composition of atmospheric sulfate has been determined by a number of workers and the results interpreted in terms of contributing sources and mechanisms of origin. A correlation between the 18O enrichment of atmospheric water and airborne particulate sulfate has been observed. Laboratory preparations of sulfate made from sulfur dioxide by two sets of sequential reactions, hydrolysis followed by oxidation and oxidation followed by hydrolysis, yielded products of distinguishable oxygen-isotope composition. Oxygen isotopic analysis of simultaneously collected field samples of ambient sulfate, sulfur dioxide, and water vapor indicated seasonal trends for all of the major constituents of atmospheric sulfation processes. Some isotopic data were also obtained on precipitation and precipitation sulfates. Field results suggest that ambient sulfates collected in the area of Argonne correpond more closely in oxygen isotope composition to a sulfate molecule containing two oxygens originating from sulfur dioxide, one oxygen from air and one oxygen from condensed-phased atmospheric water, SO/sub s/O/sub s/O/sub cw/O2-/sub a/, than to the molecule SO/sub s/O/sub s/O/sub wv/O2/sub a/ in which one oxygen originates from vapor-phase atmospheric water

  2. Stable isotope ratio measurements in atmospheric sulphate studies

    International Nuclear Information System (INIS)

    The isotopic composition of atmospheric sulphate has been determined by a number of workers and the results interpreted in terms of contributing sources and mechanisms of origin. A correlation between the 18O enrichment of atmospheric water airborne particulate sulphate has been observed. Laboratory preparations of sulphate made from sulphur dioxide by two sets of sequential reactions, (1) hydrolysis followed by oxidation and (2) oxidation followed by hydrolysis, yielded products of distinguishable oxygen-isotope composition. Oxygen isotopic analysis of simultaneously collected field samples of ambient sulphate, sulphur dioxide, and water vapour indicated seasonal trends for all of the major constituents of atmospheric sulphation processes. Some isotopic data were also obtained on precipitation and precipitation sulphates. Field results suggest that ambient sulphates collected in the area of Argonne correspond more closely in oxygen isotope composition to a sulphate molecule containing two oxygens originating from sulphur dioxide, one oxygen from air and one oxygen from condensed-phase atmospheric water than to the molecule in which one oxygen originates from vapourphase atmospheric water. (author)

  3. Stable isotope ratios of atmospheric CO_{2} and CH_{4} over Siberia measured at ZOTTO

    Science.gov (United States)

    Timokhina, Anastasiya; Prokushkin, Anatily; Lavric, Jost; Heimann, Martin

    2016-04-01

    The boreal and arctic zones of Siberia housing the large amounts of carbon stored in the living biomass of forests and wetlands, as well as in soils and specifically permafrost, play a crucial role in earth's global carbon cycle. The long-term studies of greenhouse gases (GHG) concentrations are important instruments to analyze the response of these systems to climate warming. In parallel to GHG observations, the measurements of their stable isotopic composition can provide useful information for distinguishing contribution of individual GHG source to their atmospheric variations, since each source has its own isotopic signature. In this study we report first results of laboratory analyses of the CO2 and CH4 concentrations, the stable isotope ratio of δ13C-CO2, δ18O-CO2, δ13C-CH4, δD-CH4 measured in one-liter glass flasks which were obtained from 301 height of ZOTTO (Zotino Tall Tower Observatory, near 60° N, 90° E, about 20 km west of the Yenisei River) during 2008 - 2013 and 2010 - 2013 for stable isotope composition of CO2 and CH4. The magnitudes of δ13C-CO2 and δ18O-CO2 in a seasonal cycle are -1.4±0.1‰ (-7.6 - -9.0‰) and -2.2±0.2‰ (-0.1 - -2.3‰), respectively. The δ13C-CO2 seasonal pattern opposes the CO2 concentrations, with a gradual enrichment in heavy isotope occurring during May - July, reflecting its discrimination in photosynthesis, and further depletion in August - September as photosynthetic activity decreases comparatively to ecosystem respiration. Relationship between the CO2 concentrations and respective δ13C-CO2 (Keeling plot) reveals isotopic source signature for growing season (May - September) -27.3±1.4‰ and -30.4±2.5‰ for winter (January - March). The behavior of δ18O-CO2 associated with both high photosynthetic rate in the June (enrichment of atmospheric CO2 by 18O as consequence of CO2 equilibrium with "heavy" leaf water) and respiratory activity of forest floor in June - October (depletion of respired CO2 by 18O

  4. Carbon-isotopic analysis of dissolved acetate

    International Nuclear Information System (INIS)

    Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degree C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4 per-thousand for acetate samples larger than 5 μmol. A full treatment of uncertainties is outlined

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

    International Nuclear Information System (INIS)

    Secondary carbonates occurring within the soils, faults, and subsurface fractures of Yucca Mountain contain some of the best available records of paleoclimate and palehydrology for the potential radioactive waste repository site. This article discusses conceptual and analytical advances being made with regard to the interpretation of stable isotope data from pedogenic carbonates, specifically related to the 13C content of soil CO2, CaCO3, precipitation mechanisms, and isotopic fractionations between parent fluids and precipitating carbonates. The 13C content of soil carbon dioxide from Yucca Mountain and vicinity shows most of the usual patterns expected in such contexts: Decreasing 13C content with depth decreasing 13C with altitude and reduced 13C during spring. These patterns exist within the domain of a noisy data set; soil and vegetational heterogeneities, weather, and other factors apparently contribute to isotopic variability in the system. Several soil calcification mechanisms appear to be important, involving characteristic physical and chemical environments and isotopic fractionations. When CO2 loss from thin soil solutions is an important driving factor, carbonates may contain excess heavy isotopes, compared to equilibrium precipitation with soil fluids. When root calcification serves as a proton generator for plant absorption of soil nutrients, heavy isotope deficiencies are likely. Successive cycles of dissolution and reprecipitation mix and redistribute pedogenic carbonates, and tend to isotopically homogenize and equilibrate pedogenic carbonates with soil fluids

  6. Sulfur isotope ratios and the origins of the aerosols and cloud droplets in California stratus

    International Nuclear Information System (INIS)

    Marine aerosols often have sulfur-to-chloride ratios greater than that found in seawater. Sulfur isotope ratios (34S/32S) were measured in aerosol and cloud droplet samples collected in the San Francisco Bay Area in an attempt to understand the processes that produce the observed sulfur-to-chloride ratios. Seawater sulfur usually has very high sulfur isotope ratios: fossil fuel sulfur tends to have smaller isotope ratios and sulfur of bacteriogenic origin still smaller. Samples collected in unpolluted marine air over the hills south of San Francisco had sulfur ratios that were significantly lower than the values for samples collected in nearby areas that were subject to urban pollution. The highest sulfur isotope ratios were found in the offshore seawater. The results suggest bacteriogenic origins, of the marine air sulfur aerosol material. The low isotope ratios in the marine air cannot be explained as a mixture of seawater sulfur and pollutant sulfur, because both tend to have higher isotope ratios. (Auth.)

  7. Global modelling of H2 mixing ratios and isotopic compositions with the TM5 model

    Directory of Open Access Journals (Sweden)

    R. L. Langenfelds

    2011-07-01

    Full Text Available The isotopic composition of molecular hydrogen (H2 contains independent information for constraining the global H2 budget. To explore this, we have implemented hydrogen sources and sinks, including their stable isotopic composition and isotope fractionation constants, into the global chemistry transport model TM5. For the first time, a global model now includes a simplified but explicit isotope reaction scheme for the photochemical production of H2. We present a comparison of modelled results for the H2 mixing ratio and isotope composition with available measurements on seasonal to inter annual time scales for the years 2001–2007. The base model results agree well with observations for H2 mixing ratios. For δD[H2], modelled values are slightly lower than measurements. A detailed sensitivity study is performed to identify the most important parameters for modelling the isotopic composition of H2. The results show that on the global scale, the discrepancy between model and measurements can be closed by adjusting the default values of the isotope effects in deposition, photochemistry and the stratosphere-troposphere exchange within the known range of uncertainty. However, the available isotope data do not provide sufficient information to uniquely constrain the global isotope budget. Therefore, additional studies focussing on the isotopic composition near the tropopause and on the isotope effects in the photochemistry and deposition are recommended.

  8. Carbon isotopic thermometry calibrated by dolomite-calcite solvus temperatures

    International Nuclear Information System (INIS)

    The temperature dependence of carbon isotopic fractionations between calcite and graphite, and between dolomite and graphite are calibrated by the calcite-dolomite solvus geothermometry using marbles collected from the contact metamorphic aureole in the Kasuga area, central Japan. The carbon isotopic fractionations systematically decrease with increasing metamorphic temperature. The concordant relationships between the fractionations and solvus temperatures which are presented, are approximately linear with T-2 over the temperature range, 400 deg to 680 deg C. They suggest that carbon isotopic equilibria between carbonates and graphite were attained in many cases. The equation for the calcite-graphite system has a slope steeper than Bottinga's (1969) results. It is, however, in good agreement with that of Valley and O'Neil (1981) in the temperature range from 600 deg to 800 deg C. Because of the relatively high sensitivity to temperature, these isotopic geothermometers are useful for determining the temperatures in moderate- to high-grade metamorphosed carbonate rocks. (author)

  9. Carbon isotope anomaly in the major plant C1 pool and its global biogeochemical implications

    Directory of Open Access Journals (Sweden)

    J. T. G. Hamilton

    2004-08-01

    Full Text Available We report that the most abundant C1 units of terrestrial plants, the methoxyl groups of pectin and lignin, have a unique carbon isotope signature exceptionally depleted in 13C. Plant-derived C1 volatile organic compounds (VOCs are also anomalously depleted in 13C compared with Cn+1 VOCs. The results confirm that the plant methoxyl pool is the predominant source of biospheric C1 compounds of plant origin such as methanol, chloromethane and bromomethane. Furthermore this pool, comprising ca. 2.5% of carbon in plant biomass, represents an important substrate for methanogenesis and could be a significant source of isotopically light methane entering the atmosphere. Our findings have significant implications for the use of carbon isotope ratios in elucidation of global carbon cycling. Moreover methoxyl groups could act as markers for biological activity in organic matter of terrestrial and extraterrestrial origin.

  10. Carbon isotope anomaly in the major plant C1 pool and its global biogeochemical implications

    Directory of Open Access Journals (Sweden)

    F. Keppler

    2004-01-01

    Full Text Available We report that the most abundant C1 units of terrestrial plants, the methoxyl groups of pectin and lignin, have a unique carbon isotope signature exceptionally depleted in 13C. Plant-derived C1 volatile organic compounds (VOCs are also anomalously depleted in 13C compared with Cn+1 VOCs. The results confirm that the plant methoxyl pool is the predominant source of biospheric C1 compounds of plant origin such as methanol, chloromethane and bromomethane. Furthermore this pool, comprising ca 2.5% of carbon in plant biomass, could be an important substrate for methanogenesis and thus be envisaged as a possible source of isotopically light methane entering the atmosphere. Our findings have significant implications for the use of carbon isotope ratios in elucidation of global carbon cycling. Moreover methoxyl groups could act as markers for biological activity in organic matter of terrestrial and extraterrestrial origin.

  11. Recent measurements of 234U/238U isotope ratio in spring waters from the Hadzici area

    International Nuclear Information System (INIS)

    The Hadzici area has become interesting for investigation since depleted uranium ammunition had been employed in 1995 during the NATO air strike campaign in Bosnia and Herzegovina. The purpose of this study is to determine uranium concentration and 234U/238U activity ratio in the spring waters of this area and to investigate their relationship, as well as spatial variations. The spring water samples were taken at 18 sites in total. For the determination of uranium radioisotopes, radiochemical separation procedure followed by alpha-particle spectrometry was applied. Uranium concentration in analyzed waters range from 0.15 to 1.12 μg/L. Spring waters from carbonate based sediments have a lower uranium concentration of between 0.15 and 0.43 μg/L, in comparison to waters sampled within sandstone-based sediments ranging from 0.53 to 1.12 μg/L. Dissolved uranium shows significant spatial variability and correlation with bedrock type confirmed by Principal Component Analysis and Hierarchical Cluster Analysis. The majority of the analyzed waters have a 234U/238U activity ratio ranging from 1.02 to 1.90, of which half of the results range between 1.02 and 1.16. No apparent depleted uranium (DU) contamination was observed, as 234U/238U activity ratio is dependent on geochemical conditions in the environment. Even though the tested spring waters demonstrate significant variability in uranium concentration, 234U/238U activity ratio and 234U excess, waters with similar uranium isotopic signatures are observable within the region. The guidelines on the spatial redistribution of dissolved uranium (corresponding to 238U mass concentration), along with 234U/238U activity ratios were provided by the Inverse Distance Weighting (IDW) method. Waters having similar isotopic signature have been delineated. -- Highlights: ► Uranium concentration in analyzed spring waters ranges from 0.15 to 1.12 μg/L. ► Dissolved uranium shows correlation with bedrock type. ► Low 234U/238U

  12. Results from an interlaboratory exercise on the determination of plutonium isotopic ratios by gamma spectrometry

    International Nuclear Information System (INIS)

    Results form interlaboratory comparison measurements on the determination of plutonium isotopic ratios by gamma spectrometry, organized by the ESARDA Working Group on Techniques and Standards for Nondestructive Analysis, are presented and discussed. Nine laboratories from nine countries or international organizations participated in the intercomparison exercise, which included both laboratories' own measurements on the plutonium isotopic reference materials NBS-SRM 946, 947, 948 and comparison analyses of gamma spectra from these materials distributed to the participating laboratories. Results from the intercomparison analyses have been used to reevaluate some gamma branching intensity ratios required for plutonium isotopic ratio measurements. (orig.)

  13. Biomass carbon-14 ratio measured by accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Measurement methods of a biomass carbon ratio in biomass products based on 14C-radiocarbon concentration have been reviewed. Determination of the biomass carbon ratio in biomass products is important to secure the reliance in the commercial market, because the 'biomass products' could contain products from petroleum. The biomass carbon ratio can be determined from percent Modern Carbon (pMC) using ASTM D6866 methods. The pMC value is calculated from the comparison between the 14C in sample and 14C in reference material. The 14C concentration in chemical products can be measured by liquid scintillation counter (LSC) and accelerator mass spectrometry (AMS). LSC can be applicable to determine the biomass carbon ratio for liquid samples such as gasoline with bioethanol (E5 or E10). On the other hand, AMS can be used to determine the biomass carbon ratio for almost all kinds of organic and inorganic compounds such as starch, cellulose, ethanol, gasoline, or polymer composite with inorganic fillers. AMS can accept the gaseous and solid samples. The graphite derived from samples included in solid phase is measured by AMS. The biomass carbon of samples derived from wood were higher than 100% due to the effect of atomic bomb test in the atmosphere around 1950 which caused the artificial 14C injection. Exact calculation methods of the biomass carbon ratio from pMC will be required for the international standard (ISO standard). (author)

  14. Probing the Isotopic Composition of Surface Waters Across Isotopic Extremes of Cryogenian Carbonates

    Science.gov (United States)

    Bosak, T.; Matys, E. D.; Bird, L. R.; Macdonald, F. A.; Freeman, K. H.

    2012-12-01

    Neoproterozoic carbonate strata record unusually large and positive carbon isotope values (δ13Ccarb from 4 to 10 per mil), and stratigraphically extensive large negative carbon isotope excursions (δ13Ccarb red algae, respectively, they can be used as tracers of organic matter production in surface waters. Fossil tests were extracted by acid maceration, cleaned and analyzed morphologically and microscopically. Their carbon isotopic composition was measured using a nano-scaled elemental analyzer inlet (nano-EA-IRMS), with ±1 per mil analytical precision. To date, we analyzed 12 samples of 100-150 organic tests, representing 3 different fossiliferous parts of the Tayshir anomaly (δ13Ccarb +5 per mil), respectively. More samples, including those of fossil algae and tests from the carbonate strata overlying the Tayshir anomaly, are currently being analyzed. Initial data reveal a rather constant isotopic composition of organic carbon in fossil tests (δ13Cfossil), with values of -23 ±1 per mil both within 13C-enriched and 13C-depleted carbonates. The isotopic difference between δ13Cfossil and 13C-enriched carbonates is 28 to 30 per mil, suggesting maximal isotopic fractionation by primary producers, and little environmental (or diagenetic) processing of primary photosynthetic carbon. The carbonates of the Tayshir anomaly preserve two organic materials: matrix or bulk carbon characterized by a δ13Corg that covaries with δ13Ccarb, and a small, but morphologically diagnostic component whose δ13Cfossil values do not covary with δ13Ccarb. The stratigraphic thickness (~ 50 m) and isotopic heterogeneity of the organic matter within the Tayshir anomaly (~ 50 m) suggest a prolonged and large contribution of organic carbon remineralization.

  15. Sulfur isotope ratio measurements by MC-ICPMS of boon or bane?

    International Nuclear Information System (INIS)

    Full text: The variation of the isotopic composition of sulfur is influenced by biological and anthropogenic activities. Thus it proved to be a suitable tracer in provenance studies of food and beverages. Nonetheless, mass bias and interferences hamper the accurate and precise determination of the isotopic composition. Different ICPMS instruments were investigated for their potential to assess sulfur isotope ratios for food provenance studies, and were applied to a variety of food matrices. (author)

  16. Environmental Isotope Ratios of River Water in the Danube Basin

    International Nuclear Information System (INIS)

    The objectives of the Danube study were documentation of existing data and completion of long term data sets (2H, 3H, 18O), continuation of monthly sampling of river water, investigation of short term influences, and preliminary interpretation of long term isotope records of river water with respect to hydrological processes, meteorological conditions and environmental changes. Furthermore, this report includes the complete 3H and 18O data set for the Danube at Vienna (1963-2005) and a summary of the results from the Joint Danube Survey 2 (2007). δ18O values of JDS2 river water samples ranged from -13.1 per mille (Inn, alpine river) up to -6.4 per mille (River Sio, evap oration influence). The δ18O value of the Danube increased from -10.8 per mille after the confluence of the Inn River with the upper Danube up to -9.6 per mille at the mouth, with a major change after the inflow of Tisa and Sava. The isotopic composition of river water in the Danube Basin is mainly governed by the isotopic composition of precipitation in the catchment area, while evaporation effects play only a minor role. Short term and long term isotope signals from precipitation are thus transmitted through the whole catchment. Tritium concentrations in most parts of the Danube river system lay around 10 TU during the JDS2 period and reflected the actual 3H content of precipitation in Central Europe, but 3H values up to 40 TU in the Danube and up to 250 TU in some tributaries are clear evi dence for discontinuous releases of 3H from local sources (nuclear power plants) into the rivers. (author)

  17. NUSIMEP-7: Uranium isotope amount ratios in uranium particles

    OpenAIRE

    TRUYENS Jan; STEFANIAK Elzbieta; MIALLE SÉBASTIEN; Aregbe, Yetunde

    2011-01-01

    The Additional Protocol (AP) authorizes safeguards authorities to verify the absence of undeclared nuclear activities in all parts of a state’s nuclear fuel cycle as well as any other location where nuclear material is or may be present. As part of the Additional Protocol, environmental sampling has become an important tool for the detection of non-declared nuclear activities. In environmental sampling micrometer-sized uranium particles with an isotopic composition characteristic for the proc...

  18. Is modern climate variability reflected in compund specific hydrogen isotope ratios of sedimentary biomarkers?

    Science.gov (United States)

    Sachse, D.; Radke, J.; Gleixner, G.

    2003-04-01

    Compound specific hydrogen isotope ratios are emerging as a new palaeoclimatic and palaeohydrological proxy. First reconstructions of palaeoclimate using D/H ratios from n-alkanes are available (Andersen et al. 2001, Sauer et al. 2001, Sachse et al. 2003). However, a systematic approach comparing recent sedimentary biomarkers with climate data is still lacking. We are establishing an ecosystem study of small, ground water fed lakes with known limnology. Nearly all lakes are close to a long-term climate-monitoring site (CARBOEUROPE flux tower site, IAEA precipitation monitoring) delivering ecophysiological and climatic data as temperature, precipitation, evapotranspiration etc. Water, primary biomass, plant, soil and sediment were sampled from lakes and the surrounding ecosystem along a climatic and isotopic gradient in meteoric waters from northern Finland (deltaD: -130 permil vs. VSMOW) to southern Italy (deltaD: -30 permil vs. VSMOW, IAEA 2001). Biomarkers were extracted from the samples to test if climatic variability is reflected in their D/H ratios. First results of the factors influencing the hydrogen isotope composition of sedimentary biomarkers and their use as palaeoclimatic and palaeohydrological proxy will be presented. Andersen N, Paul HA, Bernasconi SM, McKenzie JA, Behrens A, Schaeffer P, Albrecht P (2001) Large and rapid climate variability during the Messinian salinity crisis: Evidence from deuterium concentrations of individual biomarkers. Geology 29:799-802 IAEA (2001) GNIP Maps and Animations. International Atomic Energy Agency, Vienna. Accessible at http://isohis.iaea.org Sachse D, Radke J, Gaupp R, Schwark L, Lüniger G, Gleixner G (2003) Reconstruction of palaeohydrological conditions in a lagoon during the 2nd Zechstein cycle through simultaneous use of deltaD values of individual n-alkanes and delta18O and delta13C values of carbonates. International Journal of Earth Sciences, submitted Sauer PE, Eglington TI, Hayes JM, Schimmelman A

  19. Late Carboniferous to Late Permian carbon isotope stratigraphy

    DEFF Research Database (Denmark)

    Buggisch, Werner; Krainer, Karl; Schaffhauser, Maria;

    2015-01-01

    An integrated study of the litho-, bio-, and isotope stratigraphy of carbonates in the Southern Alps was undertaken in order to better constrain δ13C variations during the Late Carboniferous to Late Permian. The presented high resolution isotope curves are based on 1299 δ13Ccarb and 396 δ13Corg...

  20. Carbon Monoxide Isotopes: On the Trail of Galactic Chemical Evolution

    Science.gov (United States)

    Langer, W.

    1995-01-01

    From the early days of the discovery of radio emission from carbon monoxide it was realized that it offered unusual potential for under- standing the chemical evolution of the Galaxy and external galaxies through measurements of molecular isotopes. These results bear on stellar nucleosynthesis, star formation, and gases in the interstellar medium. Progress in isotopic radio measurements will be reviewed.

  1. Application of carbon isotope analyses in food technology

    International Nuclear Information System (INIS)

    The vast economic size of the food market offers great temptations for the production and sale of fraudulent products, adulterated products and synthetic products that are labeled as natural ones. Conventional techniques of chemical analyses have served the food industry well for many years but are limited in their ability to detect certain types of fraudulent or mislabelled products. The aversion to added sugar and the demand for 'all natural' food products among consumers has led to a great deal of mislabelling on the part of food processors in order to achieve greater economic gain. The nature of deceptions detectable by carbon Stable Isotope Ratio Analysis (SIRA) in food technology falls into three broad categories. The most common is the adulteration of an expensive natural product, such as apple juice, with a much cheaper natural product such as cane sugar or high fructose corn syrup (HFCS). The second is outright falsification of a food. An example is maple syrup produced by simple addition of maple flavoring to a sugar syrup or HFCS. The third general category is the sale of synthetic materials as natural ones or the addition of synthetic materials to natural ones in order to increase the volume of the product. The procedure for using carbon SIRA in monitoring food products involves two stages. It must first be established that the product to be analyzed, or some specific component of it, has a particular isotopic composition that can be distinguished from that of the materials that might be used to adulterate it. Potential adulterating components are then analyzed to establish their isotopic identity. The carbon SIRA method cannot, in general, be used to establish purity unequivocally but it can be used to establish impurity or adulteration with a high degree of success. The overall process of carbon SIRA consists of three stages: selection of the sample or the isolation of the particular compound to be analyzed, conversion of this compound into CO2 gas

  2. Uranium Isotopic Ratio Analysis of U-Bearing Particulates By SIMS in CIAE

    International Nuclear Information System (INIS)

    In this paper measurement method of uranium isotope ratio of uranium-bearing particles in swipe samples was introduced; Swipe sample screening program was proposed on the basis of studying various destructive assay and non-destructive assays. Scanning electron microscope(SEM) equipped with an energy dispersive X-ray fluorescence(XRF) system was applied to located the deposited uranium-containning particles on the graphite support, particle's composition and size can be identified. Some isotope ratio results were compared with those of other bulk analytical methods; By measuring the same prepared sample, we got the U-particle isotopic ratio data similar to those from IAEA NWAL, indication that our operation parameters and experimental conditions are viable and can be used for measurement of U-particle isotope ratio from swipe samples

  3. Lead isotope ratios as a tracer for lead contamination sources: A lake Andong case study

    Directory of Open Access Journals (Sweden)

    Kim Y. H

    2013-04-01

    Full Text Available The objective of this study was to evaluate stable Pb isotope signatures as a tracer for Pb contamination in Lake Andong. For Pb isotope analysis, we collected water and sediment from Lake Andong, particles in the air, soils, and stream water, mine tailings, sludge and wastewater from zinc smelting around lake Andong watershed. The results showed that Pb isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb for zinc concentrate were 18.809 ± 0.322, 15.650 ± 0.062, and 38.728 ± 0.421, respectively. In wastewater, isotopic ratio values (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb were 17.363 ± 0.133, 15.550 ± 0.025, and 37.217 ± 0.092, respectively. Additionally, isotopic ratio values (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb for sludge were 17.515 ± 0.155, 15.537 ± 0.018, and 37.357 ± 0.173, respectively. These values were similar to those in zinc and lead concentrate originated from Canada and South America. In contrast, Pb isotope ratios of soil, tailings and sediment from Lake Andong were similar to those of Korean ore. Atmospheric particles showed different patterns of Pb isotope ratios from sediments, soils, and zinc smelting and this needs further investigation in order to identify atmospheric Pb sources.

  4. Use of Isotope Ratio Determination ((13)C/(12)C) to Assess the Production Method of Sparkling Wine.

    Science.gov (United States)

    Rossier, Joël S; Maury, Valérie; Gaillard, Laetitia; Pfammatter, Elmar

    2016-01-01

    The production of a sparkling wine can be performed with different methods taking from a few weeks to several years, which often justifies a difference in added value for the consumer. This paper presents the use of isotope ratio δ(13)C measurements combined with physico-chemical analyses for the determination of mislabelling of sparkling wines produced by 'ancestral', 'traditional', 'closed tank' or 'gasification' methods. This work shows that the isotope composition of CO2 compared with that of the corresponding dried residue of wine (DRW) can assess whether carbonate CO2 in a sparkling wine originates from alcohol fermentation or from artificial gas addition. Isotopic ratios expressed as δ(13)CCO2 and δ(13)CDRW measurements have been obtained for each wine by gasbench isotopic ratio mass spectroscopy and cavity ring down infrared spectroscopy, respectively. When the difference between δ(13)CCO2 and δ(13)CDRW is negative, the presence of artificial CO2 can be undoubtedly inferred, which would exclude the production methods 'ancestral' or 'traditional' for instance. Other parameters such as alcohol content, sugar and acid distributions are also important to complete the analytical panel to aid fraud tracking. PMID:27198811

  5. Accuracy of delta 18O isotope ratio measurements on the same sample by continuous-flow isotope-ratio mass spectrometry

    Science.gov (United States)

    The doubly labeled water method is considered the reference method to measure energy expenditure. Conventional mass spectrometry requires a separate aliquot of the same sample to be prepared and analyzed separately. With continuous-flow isotope-ratio mass spectrometry, the same sample could be analy...

  6. Isotope ratios of uranium using high resolution inductively coupled plasma-mass spectrometry (ICP-MS)

    International Nuclear Information System (INIS)

    Actinide element isotope ratios have been determined in environmental samples using high resolution ICP-MS with ultrasonic nebulization. Precisions as low as 0.1% RSD have been achieved using various methods of acquisition. The methodology has been used for environmental monitoring of uranium isotope ratios as an indicator of nuclear activity. Also, it has been applied to calcite dating studies as a measure of past geochemical disturbances

  7. Graphite Isotope Ratio Method Development Report: Irradiation Test Demonstration of Uranium as a Low Fluence Indicator

    International Nuclear Information System (INIS)

    This report describes an irradiation test designed to investigate the suitability of uranium as a graphite isotope ratio method (GIRM) low fluence indicator. GIRM is a demonstrated concept that gives a graphite-moderated reactor's lifetime production based on measuring changes in the isotopic ratio of elements known to exist in trace quantities within reactor-grade graphite. Appendix I of this report provides a tutorial on the GIRM concept

  8. Isotopic distribution of carbon from sewage sludge and eutrophication in the sediments and food web of estuarine ecosystems

    International Nuclear Information System (INIS)

    Stable isotope ratios (δ13C) from samples of water, sediments, and biota traced the behavior of organic carbon for 3 summer months in estuarine mesocosms (three controls, three with added sewage sludge, three with added inorganic nutrients). Isotope ratios proved to be a useful quantitative tracer for sewage carbon as well as for the fresh phytoplanktonic carbon produced during nutrient fertilization. Sewage sludge sedimented within hours of its addition, and approximately 50% remained in sediments after 99 days. The sludge was not inert, but was biologically oxidized at rates similar to those of phytoplankton carbon. Its residence time in the water column was too short for uptake by zooplankton, but it was readily assimilated by some benthic organisms. Fresh phytoplanktonic carbon from nutrient-induced blooms was isotopically heavy and thus distinguishable from old primary production (fixed before the experiment). It flowed through the pelagic and benthic food webs more extensively and more uniformly than did sludge carbon

  9. The carbon isotope biogeochemistry of methane production in anoxic sediments. 1: Field observations

    Science.gov (United States)

    Blair, Neal E.; Boehme, Susan E.; Carter, W. Dale, Jr.

    1993-01-01

    The natural abundance C-13/C-12 ratio of methane from anoxic marine and freshwater sediments in temperate climates varies seasonally. Carbon isotopic measurements of the methanogenic precursors, acetate and dissolved inorganic carbon, from the marine sediments of Cape Lookout Bight, North Carolina were used to determine the sources of the seasonal variations at that site. Movement of the methanogenic zone over an isotopic gradient within the dissolved CO2 pool appears to be the dominant control of the methane C-13/C-12 ratio from February to June. The onset of acetoclastic methane-production is a second important controlling process during mid-summer. An apparent temperature dependence on the fractionation factor for CO2-reduction may have a significant influence on the isotopic composition of methane throughout the year.

  10. Seasonal dynamics of stable isotopes and element ratios in authigenic calcites during their precipitation and dissolution, Sacrower See (northeastern Germany

    Directory of Open Access Journals (Sweden)

    Bernd ZOLITSCHKA

    2009-08-01

    Full Text Available The seasonal evolution of chemical and physical water properties as well as particle fluxes was monitored in Sacrower See (northeastern Germany during two consecutive years (Oct 2003 - Oct 2005. Additonally, we measured δ18O and δ13C as well as Sr:Ca and Mg:Ca ratios of authigenic calcites that were collected in sequencing sediment traps in order to disentangle environmental and climatic factors controlling these parameters. In particular, our aim was to find out if element ratios and the isotopic composition of calcites reflect changes in water and air temperatures. Lake water is highly enriched in 18O (-1.3 to -2.5‰ VSMOW with an evaporative increase of 0.6‰ during summer. Values are 5-6‰ more positive than groundwater values and 4-5‰ more positive than long-term weighted annual means of precipitation. During spring and summer, high amounts of dissolved phosphate cause eutrophic conditions and calcite precipitation in isotopic disequilibrium. Measured values are depleted in 18O by 2 to 10‰ compared to calculated equilibrium values. Resuspension and partial dissolution of calcite in the water column contribute to this isotopic divergence in summer and autumn as δ18Oca and δ13C values increased in the hypolimnion during this time. Mg:Ca and Sr:Ca ratios are altered by dissolution as well. In the hypolimnion these ratios were higher than in the epilimnion. Another reason for the huge deviation between measured and theoretical δ18Oca values during summer is the occurrence of large amounts of Phacotus lenticularis in the carbonate fraction. High amounts of Phacotus lead to more negative δ18Oca and more positive δ13C values. Several characteristics of δ18Oca and δ13C are also reflected by Mg:Ca and Sr:Ca ratios and isotopic composition of oxygen and carbon were influenced by the onset and stability of stratification. Especially the earlier onset of stratification in 2005 caused higher sediment fluxes and more positive carbon and

  11. Comparison of mass spectrometric methods (TE, MTE and conventional) for uranium isotope ratio measurements

    International Nuclear Information System (INIS)

    The isotope ratio measurement techniques - total evaporation (TE), modified total evaporation (MTE), and conventional - used for characterization measurements of certified reference materials by thermal ionization mass spectrometer instruments are compared. The advantages of each method, the fractionation profiles resulting from the measurement techniques, and factors affecting systematic components of bias in the isotope ratio measurements are discussed. The TE and MTE techniques yield major ratios and the conventional and MTE techniques yield minor ratios of comparable quality (in terms of precision and accuracy). (author)

  12. Noble gas isotopic composi-tions of deep carbonate rocks from the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Abundances and isotopic compositions of noble gases (He, Ne, Ar, Kr) with various existence states in carbonate rocks from the Tacanl Well have been investigated by means of the stepwise heating technique. The elemental abundance patterns of noble gases in the samples show the enrichment of heavy noble gases and depletion of 20Ne relative to the atmosphere, which are designated as type- I and are similar to that observed in water, natural gases and sedimentary rocks. The 3He/4He ratios of deep carbonate samples at lower and medium temperature (300-700℃) and a majority of samples at higher temperature (1100-1500℃) steps are very similar to those of natural gases in the same strata in this area, this feature of radiogenic crustal helium shows that the Tazhong Uplift is relatively stable.However, significant helium and argon isotopic anomalies are found at the 1100℃ step in the Middle-Upper Ordoviclan carbonate rock, suggesting the incorporation of manfie-derived volatiles, this may be due to minor igneous minerals contained in sedimentary carbonate rocks. The 40Ar/36Ar ratios in the Cambrian carbonate rock are slightly higher than those in Ordovician carbonate rocks, which may reflect the influence of the chronologic accumulation effect of crust radiogenic 40Ar. Argon isotopes of various existence states in source rocks are much more different, both 38Ar/36Ar and 40Ar/36Ar ratios at the higher temperature steps are higher than those at the lower temperature steps.``

  13. Tracing sewage and natural freshwater input in a Northwest Mediterranean bay: Evidence obtained from isotopic ratios in marine organisms

    International Nuclear Information System (INIS)

    Elemental carbon and nitrogen levels and isotope ratios were assessed in different biological compartments of a Northwest (NW) Mediterranean bay to trace the various sources of nutrient input from natural (river runoffs) and anthropogenic (harbor outflows, fish farms and urban sewage outfall) sources. Samples from transplanted mussels and natural sea grass communities (Posidonia oceanica leaves and epiphytes) were harvested from different locations throughout the bay during the touristic summer and rainy seasons. The results from the nitrogen analysis revealed that sewage and harbor outflow promote higher nitrogen levels, enrichment of 15N in the tissues, and a higher seasonal variability in sea grass and epiphytes. In mussel tissues, the δ15N was also influenced by sewage and harbor outflow, whereas δ13C was influenced by terrestrial inputs. These results suggest that natural and anthropogenic nutrient inputs have a temporary and localized influence and affect the sensitivity of natural isotopic ratios to changes in hydrologic conditions, especially to rain and tourism.

  14. Drought indicated in carbon-13/carbon-12 ratios of Southwestern tree rings

    International Nuclear Information System (INIS)

    Stomatal closure during periods of moisture deficiency should theoretically lead to elevated 13C/12C ratios as reduction of available CO2 leads to diminished photosynthetic discrimination against 13C in favor of 12C. Stable-carbon isotope ratio chronologies developed from 5-yr tree-ring groups at 17 sites in six southwestern states were tested for a drought relationship by first fitting a spline curve to each chronology to remove the long-term trend and calculating indices as the ratio of actual to spline curve value. The time series of “Del Indices” so developed are significantly correlated with 5-yr mean Palmer Hydrological Drought Indices (post-1930 period) and reconstructed July Palmer Drought Severity Indices from respective areas. Overall, in the period since 1790, the driest pentads were 1900–04 and 1960–64, whereas the wettest were 1980–84 and 1915–19. Maps of drought represented for two pentads seem to be reasonable representations, although spatial correlations of Del Indices with PHDI were generally not significant. These Del Index drought reconstructions may provide a useful measure of past physiological response to drought (stomatal closure), although the present cost of analysis would prevent this from being a routine method. (author)

  15. Water isotopic ratios from a continuously melted ice core sample

    CERN Document Server

    Gkinis, V; Blunier, T; Bigler, M; Schüpbach, S; Kettner, E; Johnsen, S J

    2014-01-01

    A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We built an interface between a Wavelength Scanned Cavity Ring Down Spectrometer (WS-CRDS) purchased from Picarro Inc. and a Continuous Flow Analysis (CFA) system. The system offers the possibility to perform simultaneous water isotopic analysis of $\\delta^{18}$O and $\\delta$D on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub ${\\mu}$l amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100% efficiency in a home made oven. A calibration procedure allows for proper reporting of the data on the VSMOW--SLAP scale. Application of spectral methods yields the combined uncertainty of the system at below 0.1 permil and 0.5 permil for $\\delta^{18}$O and $\\delta$D, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sampl...

  16. Modeling the carbon isotope composition of bivalve shells (Invited)

    Science.gov (United States)

    Romanek, C.

    2010-12-01

    The stable carbon isotope composition of bivalve shells is a valuable archive of paleobiological and paleoenvironmental information. Previous work has shown that the carbon isotope composition of the shell is related to the carbon isotope composition of dissolved inorganic carbon (DIC) in the ambient water in which a bivalve lives, as well as metabolic carbon derived from bivalve respiration. The contribution of metabolic carbon varies among organisms, but it is generally thought to be relatively low (e.g., 90%) in the shells from terrestrial organisms. Because metabolic carbon contains significantly more C-12 than DIC, negative excursions from the expected environmental (DIC) signal are interpreted to reflect an increased contribution of metabolic carbon in the shell. This observation contrasts sharply with modeled carbon isotope compositions for shell layers deposited from the inner extrapallial fluid (EPF). Previous studies have shown that growth lines within the inner shell layer of bivalves are produced during periods of anaerobiosis when acidic metabolic byproducts (e.g., succinic acid) are neutralized (or buffered) by shell dissolution. This requires the pH of EPF to decrease below ambient levels (~7.5) until a state of undersaturation is achieved that promotes shell dissolution. This condition may occur when aquatic bivalves are subjected to external stressors originating from ecological (predation) or environmental (exposure to atm; low dissolved oxygen; contaminant release) pressures; normal physiological processes will restore the pH of EPF when the pressure is removed. As a consequence of this process, a temporal window should also exist in EPF at relatively low pH where shell carbonate is deposited at a reduced saturation state and precipitation rate. For example, EPF chemistry should remain slightly supersaturated with respect to aragonite given a drop of one pH unit (6.5), but under closed conditions, equilibrium carbon isotope fractionation

  17. Chromium isotope fractionation during coprecipitation with calcium carbonate

    DEFF Research Database (Denmark)

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

    Archaean and Protoerozoic, needs careful assessment of the signal robustness and necessitates a thorough understanding of the Cr cycle in Earth system processes. We conducted experiments testing the incorporation and isotopic fractionation of chromate into the calcite lattice. Our experiments indicate...... no Cr isotope fractionation in the oceans. These experiments represent a first step toward understanding the Cr isotope signal of carbonates where fractionations will likely be ≤ 0.3 ‰ and as such, pave the way for future work to enable a reliable application of the Cr isotope proxy. References: [1...

  18. Carbon Isotopic Fractionation in Fischer-Tropsch Type Reactions and Relevance to Meteorite Organics

    Science.gov (United States)

    Johnson, Natasha M; Elsila, Jamie E.; Kopstein, Mickey; Nuth, Joseph A., III

    2012-01-01

    Fischer-Tropsch-Type (FTT) reactions have been hypothesized to contribute to the formation of organic compounds in the early solar system, but it has been difficult to identify a signature of such reactions in meteoritic organics. The work reported here examined whether temperature-dependent carbon isotopic fractionation of FTT reactions might provide such a signature. Analyses of bulk organic deposits resulting from FTT experiments show a slight trend towards lighter carbon isotopic ratios with increasing temperature. It is unlikely, however, that these carbon isotopic signatures could provide definitive provenance for organic compounds in solar system materials produced through FTT reactions, because of the small scale of the observed fractionations and the possibility that signatures from many different temperatures may be present in any specific grain.

  19. A novel high-temperature combustion based system for stable isotope analysis of dissolved organic carbon in aqueous samples. : I development and validation

    NARCIS (Netherlands)

    Federherr, E.; Cerli, C.; Kirkels, F. M. S. A.; Kalbitz, K.; Kupka, H. J.; Dunsbach, R.; Lange, L.; Schmidt, T. C.

    2014-01-01

    RATIONALE: Traditionally, dissolved organic carbon (DOC) stable isotope analysis (SIA) is performed using either offline sample preparation followed by elemental analyzer/isotope ratiomass spectrometry (EA/IRMS) or a wet chemical oxidation (WCO)-based device coupled to an isotope ratio mass spectrom

  20. Carbon isotope excursions in paleosol carbonate marking five early Eocene hyperthermals in the Bighorn Basin, Wyoming

    OpenAIRE

    H. A. Abels; Lauretano, V.; A. van Yperen; T. Hopman; Zachos, J.C.; L. J. Lourens; Gingerich, P. D.; G. J. Bowen

    2015-01-01

    Transient greenhouse warming events in the Paleocene and Eocene were associated with the addition of isotopically-light carbon to the exogenic atmosphere–ocean carbon pool, leading to substantial environmental and biotic change. The magnitude of an accompanying carbon isotope excursion (CIE) can be used to constrain both the sources and amounts of carbon released during an event, as well as to correlate marine and terrestrial records with high precision. The ...

  1. Short-term measurement of carbon isotope fractionation in plants

    International Nuclear Information System (INIS)

    Combustion-based studies of the carbon-13 content of plants give only an integrated, long-term value for the isotope fractionation associated with photosynthesis. A method is described here which permits determination of this isotope fractionation in 2 to 3 hours. To accomplish this, the plant is enclosed in a glass chamber, and the quantity and isotopic content of the CO2 remaining in the atmosphere are monitored during photosynthesis. Isotope fractionation studies by this method give results consistent with what is expected from combustion studies of C3, C4, and Crassulacean acid metabolism plants. This method will make possible a variety of new studies of environmental and species effects in carbon isotope fractionation

  2. Estimation on soil erosion dynamics using stable isotope ratios of soil organic matter

    Science.gov (United States)

    Jakab, Gergely; Zacháry, Dóra; Szalai, Zoltán; Ringer, Marianna; Szabó, Judit

    2016-04-01

    Stable isotopes are a powerful and widely used tool for tracing biogeochemical processes across the ecosystem. Measuring the stable carbon, oxygen and hydrogen isotope composition of CO2 and H2O compounds and organic matter is useful for examining the soil, plant and atmospheric carbon and water pools as they isotopic composition is altered during vegetation-soil-atmosphere exchange processes (e.g., evapotranspiration, carbon assimilation and respiration). Stable carbon and nitrogen isotopes can serve as a tracer for C and N input by plants into the soil, C turnover and soil organic matter studies. In addition, coupling of isotopic tracers with molecular biology approaches and biomarkers can lead to a better understanding of the soil ecosystem processes. This study aims to estimate soil erosion deposition and redistribution processes at catena scale on the basis of stable isotope results. Soil samples were taken from the total depth of the solum along two catenas on an intensively tilled arable Cambisol. Highest δC13 values were found on the most eroded spots, while on the deposition areas significant differences were measured among the sedimented layers. The lowest δC13 value was in the buried horizon at around 120 cm depth. From this horizon δC13 values slightly increased in both upward and downward directions. However the total organic carbon concentration was highly fluctuated in the deposited profiles and have not reached its maximum in this horizon isotope results suggest that this horizon could have been the original soil surface prior to the main erosion events. In this way the use of stable isotope changes in space can provide additional information on soil redistribution due to tillage erosion. National Hungarian Research Found K100180, G. Jakab was supported by the János Bolyai fellowship of the HAS.

  3. 温室气体及碳同位素比值傅里叶变换红外光谱分析的温度依赖关系研究%Study on temperature dependence of the greenhouse gases and carbon isotope ratio spectral analysis

    Institute of Scientific and Technical Information of China (English)

    李相贤; 王振; 徐亮; 高闽光; 童晶晶; 冯明春; 刘建国

    2015-01-01

    To study the influence of temperature change on the spectrum quantitative analysis of greenhouse gases and carbon isotope ratio,at first, the view that the quantitative analysis of greenhouse gases and δ13CO2 value was mainly determined by the absorption coefficient was analyzed theoretically, and the calculation method of the absorption coefficient was also studied. Then referring to the HITRAN database, the temperature dependence of line intensity, FWHM and absorption coefficient were studied, the results show that the effect of line intensity is stronger than the FWHM on the absorption coefficient when the pressure is constant at 1 atm while the temperature changes. At last, the temperature dependence of greenhouse gases and carbon isotope ratio quantitative analysis based on Fourier transform infrared spectroscopy (FTIR) method was confirmed through a series of experiment, and these experiments also present that the variation of carbon isotope is more serious than the greenhouse gases variation when the temperature changes, the δ13CO2 value will change 14.37‰ while the temperature changes 1 ℃. This study is the theoretical basis for the design of the temperature monitoring and controlling system of greenhouse gases and carbon isotope ration monitoring instrument based on FTIR with high-precision.%为了研究温度变化对温室气体及碳同位素比值光谱定量分析的影响,首先从理论上分析得出温室气体浓度及δ13CO2值的定量反演主要取决于吸收系数,并研究了吸收系数的计算方法。其次结合HITRAN数据库,研究了温度对线强、展宽以及吸收系数的影响规律,结果表明:压强为1 atm(1 atm=1.013×105 Pa)恒定条件下,温度变化时,吸收系数受线强变化的影响强于受展宽变化的影响。最后通过实验验证了温室气体和碳同位素比值傅里叶变换红外光谱( FTIR )反演的温度依赖关系,其中碳同位素比值受温度变化影响幅度

  4. Study on temperature dependence of the greenhouse gases and carbon isotope ratio spectral analysis%温室气体及碳同位素比值傅里叶变换红外光谱分析的温度依赖关系研究

    Institute of Scientific and Technical Information of China (English)

    李相贤; 王振; 徐亮; 高闽光; 童晶晶; 冯明春; 刘建国

    2015-01-01

    To study the influence of temperature change on the spectrum quantitative analysis of greenhouse gases and carbon isotope ratio,at first, the view that the quantitative analysis of greenhouse gases and δ13CO2 value was mainly determined by the absorption coefficient was analyzed theoretically, and the calculation method of the absorption coefficient was also studied. Then referring to the HITRAN database, the temperature dependence of line intensity, FWHM and absorption coefficient were studied, the results show that the effect of line intensity is stronger than the FWHM on the absorption coefficient when the pressure is constant at 1 atm while the temperature changes. At last, the temperature dependence of greenhouse gases and carbon isotope ratio quantitative analysis based on Fourier transform infrared spectroscopy (FTIR) method was confirmed through a series of experiment, and these experiments also present that the variation of carbon isotope is more serious than the greenhouse gases variation when the temperature changes, the δ13CO2 value will change 14.37‰ while the temperature changes 1 ℃. This study is the theoretical basis for the design of the temperature monitoring and controlling system of greenhouse gases and carbon isotope ration monitoring instrument based on FTIR with high-precision.%为了研究温度变化对温室气体及碳同位素比值光谱定量分析的影响,首先从理论上分析得出温室气体浓度及δ13CO2值的定量反演主要取决于吸收系数,并研究了吸收系数的计算方法。其次结合HITRAN数据库,研究了温度对线强、展宽以及吸收系数的影响规律,结果表明:压强为1 atm(1 atm=1.013×105 Pa)恒定条件下,温度变化时,吸收系数受线强变化的影响强于受展宽变化的影响。最后通过实验验证了温室气体和碳同位素比值傅里叶变换红外光谱( FTIR )反演的温度依赖关系,其中碳同位素比值受温度变化影响幅度

  5. Direct uranium isotope ratio analysis of single micrometer-sized glass particles

    International Nuclear Information System (INIS)

    We present the application of nanosecond laser ablation (LA) coupled to a ‘Nu Plasma HR’ multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) for the direct analysis of U isotope ratios in single, 10–20 μm-sized, U-doped glass particles. Method development included studies with respect to (1) external correction of the measured U isotope ratios in glass particles, (2) the applied laser ablation carrier gas (i.e. Ar versus He) and (3) the accurate determination of lower abundant 236U/238U isotope ratios (i.e. 10−5). In addition, a data processing procedure was developed for evaluation of transient signals, which is of potential use for routine application of the developed method. We demonstrate that the developed method is reliable and well suited for determining U isotope ratios of individual particles. Analyses of twenty-eight S1 glass particles, measured under optimized conditions, yielded average biases of less than 0.6% from the certified values for 234U/238U and 235U/238U ratios. Experimental results obtained for 236U/238U isotope ratios deviated by less than −2.5% from the certified values. Expanded relative total combined standard uncertainties Uc (k = 2) of 2.6%, 1.4% and 5.8% were calculated for 234U/238U, 235U/238U and 236U/238U, respectively. - Highlights: ► LA-MC-ICP-MS was fully validated for the direct analysis of individual particles. ► Traceability was established by using an IRMM glass particle reference material. ► Measured U isotope ratios were in agreement with the certified range. ► A comprehensive total combined uncertainty evaluation was performed. ► The analysis of 236U/238U isotope ratios was improved by using a deceleration filter.

  6. Carbon isotopes in oil and gas exploration. Examples of applications

    International Nuclear Information System (INIS)

    The use of carbon isotopes in hydrocarbon exploration is reviewed. Examples of the application of stable carbon isotopes are discussed in the fields of: (1) gas exploration, where source rocks of gas deposits or gas shows can be identified by 13C/12C analyses of methane and the exploration efforts redirected; (2) wildcat drilling, in which the carbon isotope composition of methane from the head space of canned cuttings characterizes autochthonous methane and gives information on the maturity of organic matter in relation to depth; (3) oil/oil and source-rock/oil correlation, where the 'isotopic type curve technique', a recently developed sensitive oil/oil and source-rock/oil correlation method, is discussed and applied to correlation problems in the British North Sea region. (author)

  7. Oxygen isotope ratios from tree rings containing compression wood

    International Nuclear Information System (INIS)

    Oxygen isotope determinations on the alpha-cellulose of tree rings cut from two leaning Picea engelmannii revealed significant differences between results from normal and compression wood radii. Nine samples (10-year periods) from the normal wood radius (1721-1953) in one tree showed good agreement with proxy climate information and maximum differences of 1.80/00 between the ''warmest'' and ''coolest'' decades sampled. Differences of equivalent magnitude were found between samples from the same decade from normal and compression wood radii. These differences are strongly related to the amount and/or density of compression wood present and suggest that sampling for paleoclimatic work should be restricted to complacent, erect trees without compression wood rings. (author)

  8. Biogeochemistry of the stable carbon isotopes in carboxylic acids

    International Nuclear Information System (INIS)

    The carbon isotopic compositions of the carboxyl carbons of fatty acids were determined by measuring the isotopic composition of the carbon dioxide quantitatively released from the acid. A modified version of the Schmidt decarboxylation developed and tested in this work was employed. A study of the evolution of CO2 at 5 +- 20C from the Schmidt decarboxylation of octanoic acid during the developmental program revealed two kinetic phases, each characterized by different rate constants and carbon isotope effects. The first, slower reaction phase displayed overall first-order kinetics, its rate being independent of HN3 concentration. Both pre-equilibration of the HN3-CHCl3 decarboxylation reagent with H2SO4 and saturation of the catalytic H2SO4 phase with KHSO4 drastically altered the rate of evolution and isotopic composition of the product CO2. The mechanistic implications of these results were discussed. A review of the metabolism of saturated fatty acids was made in which the impact of potential isotope fractionations in the various chemical reactions comprising the biosynthetic pathways on the intramolecular carbon isotope distribution within fatty acids was discussed

  9. Isotopic disequilibrium in Globigerina bulloides and carbon isotope response to productivity increase in Southern Ocean

    Science.gov (United States)

    Prasanna, K.; Ghosh, Prosenjit; Bhattacharya, S. K.; Mohan, K.; Anilkumar, N.

    2016-02-01

    Oxygen and carbon isotope ratios in planktonic foraminifera Globigerina bulloides collected from tow samples along a transect from the equatorial Indian ocean to the Southern Ocean (45°E and 80°E and 10°N to 53°S) were analysed and compared with the equilibrium δ18O and δ13C values of calcite calculated using the temperature and isotopic composition of the water column. The results agree within ~0.25‰ for the region between 10°N and 40°S and 75-200 m water depth which is considered to be the habitat of Globigerina bulloides. Further south (from 40°S to 55°S), however, the measured δ18O and δ13C values are higher than the expected values by ~2‰ and ~1‰ respectively. These enrichments can be attributed to either a ‘vital effect’ or a higher calcification rate. An interesting pattern of increase in the δ13C(DIC) value of the surface water with latitude is observed between 35°S and~ 60°S, with a peak at~ 42°S. This can be caused by increased organic matter production and associated removal. A simple model accounting for the increase in the δ13C(DIC) values is proposed which fits well with the observed chlorophyll abundance as a function of latitude.

  10. Variations in carbon and nitrogen stable isotopes of cryoconite

    Science.gov (United States)

    Takeuchi, N.

    2012-12-01

    Cryoconite is biogenic surface dust on snow and ice, and is commoly observed on glaciers worldwide. Because of their dark coloration, cryoconite substantially reduce surface albedo and accelerate melting of glaciers. Therefore, it is important to understand formation process of cryoconite to evaluate its effect on glacier melting. Although cryoconite consists of mineral particles and organic matter, organic fraction is more important in terms of albedo effect because it is usually darker color and accounts for major part of cryoconite in volume. The organic matter is derived from photosynthetic microbes such as cyanobacteria, and/or from windblown organic matter from ground soil around glaciers. Carbon (C) and nitrogen (N) stable isotopes of the organic matter could be useful to know their sources and to understand their cycles on glaciers. In this study, I analyzed carbon and nitrogen stable isotopes of cryoconite collected from 6 sites of different elevation from May to September on an Alaska glacier (Gulkana Glacier) to know their spatial and seasonal variations. I also analyze those collected from glaciers in Asia and Arctic to compare them among different geographical locations. Results on the Alaska glacier show that C and N stable isotopes of cryoconite organic mater significantly varied among elevations and seasons. C isotope was generally higher in lower elevation, probably due to higher photosynthetic activity in the lower elevation. In contrast, N isotope was constant on the ice area, but was lower in the snow area where the red snow algae were blooming. N isotope may be reflective of nitrogen availavility on the glacier surface. Geograpical comparison shows large variations in C and N isotopes among regions: higher C and N isotopes on Asian glaciers, lower C and N isotopes in Alaska, and lower C and higher N isotopes on Arctic glaciers. The isotope values suggest that algal production is a major carbon source on most of glaciers, but their productivity

  11. Carbon and oxygen isotope fractionation in dense interstellar clouds

    Science.gov (United States)

    Langer, W. D.; Graedel, T. E.; Frerking, M. A.; Armentrout, P. B.

    1984-01-01

    It is pointed out that isotope fractionation as a result of chemical reactions is due to the small zero-point energy differences between reactants and products of isotopically distinct species. Only at temperatures near absolute zero does this energy difference become significant. Favorable conditions for isotope fractionation on the considered basis exist in space within dense interstellar clouds. Temperatures of approximately 10 K may occur in these clouds. Under such conditions, ion-molecule reactions have the potential to distribute isotopes of hydrogen, carbon, oxygen unequally among the interstellar molecules. The present investigation makes use of a detailed model of the time-dependent chemistry of dense interstellar clouds to study cosmological isotope fractionation. Attention is given to fractionation chemistry and the calculation of rate parameters, the isotope fractionation results, and a comparison of theoretical results with observational data.

  12. [Carbon isotope fractionation inplants]. Final report

    Energy Technology Data Exchange (ETDEWEB)

    O`Leary, M.H.

    1990-12-31

    The objectives of this research are: To develop a theoretical and experimental framework for understanding isotope fractionations in plants; and to develop methods for using this isotope fractionation for understanding the dynamics of CO{sub 2} fixation in plants. Progress is described.

  13. Estimation of the contribution of soil carbon to paddy rice and soil to rice carbon transfer factor using natural abundances of stable carbon isotopes

    International Nuclear Information System (INIS)

    To obtain the soil-to-rice transfer factor (TF) of carbon-14 (14C), TF of stable carbon was estimated by measuring stable carbon isotope ratios (13C/12C) and total C concentrations in rice grain and associated soil samples collected throughout Japan. Carbon isotope ratios were reported in terms of a δ13C value. By comparing δ13C values for brown rice, white rice and bran, we concluded that white rice was the most suitable part to be used for this estimation because it reflects products from photosynthesis. The δ13C values for white rice and soil showed a weak correlation which may indicate a potential carbon supply from soil to rice. Thus we took a statistical approach to estimate the percent of soil-origin carbon in rice plants. We found that a maximum 1.6% of total carbon in rice plants was from soil under the reasonable assumptions that the carbon fractionation by paddy rice was -19 per mille and δ13C of atmospheric CO2 was -8 per mille. Maximum TF value ranged from 0.05 to 0.5 for stable carbon and the value would also be applicable for 14C because the carbon fractionation effect for 14C would be negligible in carbon transfer. (author)

  14. Stable carbon isotope biogeochemistry of lakes along a trophic gradient

    NARCIS (Netherlands)

    de Kluijver, A.; Schoon, P.L.; Downing, J.A.; Schouten, S.; Middelburg, J.J.

    2014-01-01

    The stable carbon (C) isotope variability of dissolved inorganic and organic C (DIC and DOC), particulate organic carbon (POC), glucose and polar-lipid derived fatty acids (PLFAs) was studied in a survey of 22 North American oligotrophic to eutrophic lakes. The d13C of different PLFAs were used as p

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

    International Nuclear Information System (INIS)

    Secondary carbonates occurring within the soils, faults, and subsurface fractures of Yucca Mountain contain some of the best available records of paleoclimate and paleohydrology for the potential radioactive waste repository site. This article discusses conceptual and analytical advances being made with regard to the interpretation of stable isotope data from pedogenic carbonates, specifically related to the 13C content of soil CO2, CaCO3 precipitation mechanisms, and isotopic fractionations between parent fluids and precipitating carbonates. The 13C content of soil carbon dioxide from Yucca Mountain and vicinity shows most of the usual patterns expected in such contexts: decreasing 13C content with depth (due mainly to increased importance of respired CO2), decreasing 13C with altitude (partially due to relatively more C-3 vegetation), and reduced 13C during spring (due again to higher rates of respiration, and reduced gas permeability of wet soils). These patterns exist within the domain of a noisy data set; soil and vegetational heterogeneities, weather, and other factors apparently contribute to isotopic variability in the system. Several soil calcification mechanisms appear to be important, involving characteristic physical and chemical environments and isotopic fractionations. When CO2 loss from thin soil solutions is an important driving factor, carbonates may contain excess heavy isotopes, compared to equilibrium precipitation with soil fluids. When root calcification serves as a proton generator for plant absorption of soil nutrients, heavy isotope deficiencies are likely. Successive cycles of dissolution and reprecipitation mix and redistribute pedogenic carbonates, and tend to isotopically homogenize and equilibrate pedogenic carbonates with soil fluids

  16. The application of inductively coupled plasma dynamic reaction cell mass spectrometry for measurement of selenium isotopes, isotope ratios and chromatographic detection of selenoamino acids

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt

    2000-01-01

    orders of magnitude by using methane as reactive cell gas in the DRC. By using 3% v/v methanol in water for carbon-enhanced ionisation of selenium, the sensitivity of Se-80 was 10(4) counts s(-1) per ng ml(-1) of selenium, and the estimated limit of detection was 6 pg ml(-1). The precision of the isotope...... ratios. Deuterated methane used as the DRC gas showed that hydrogen transfer from methane was not involved in the formation of SeH as SeD was absent in the mass spectrum. The almost interference-free detection of selenium by ICP-DRC-MS made the detection of the Se-80 isotope possible for detection of...

  17. Carbon isotopic studies of organic matter in Precambrian rocks.

    Science.gov (United States)

    Oehler, D. Z.; Schopf, J. W.; Kvenvolden, K. A.

    1972-01-01

    A survey has been undertaken of the carbon composition of the total organic fraction of a suite of Precambrian sediments to detect isotopic trends possibly correlative with early evolutionary events. Early Precambrian cherts of the Fig Tree and upper and middle Onverwacht groups of South Africa were examined for this purpose. Reduced carbon in these cherts was found to be isotopically similar to photosynthetically produced organic matter of younger geological age. Reduced carbon in lower Onverwacht cherts was found to be anomalously heavy; it is suggested that this discontinuity may reflect a major event in biological evolution.

  18. Sr isotopic characteristics in two small watersheds draining typical silicate and carbonate rocks: implication for the studies on seawater Sr isotopic evolution

    Science.gov (United States)

    Wu, W. H.; Zheng, H. B.; Yang, J. D.

    2013-06-01

    We systematically investigated Sr isotopic characteristics of small silicate watershed - the tributary Xishui River of the Yangtze River, and small carbonate watershed - the tributary Guijiang River of the Pearl River. The results show that the Xishui River has relatively high Sr concentrations (0.468-1.70 μmol L-1 in summer and 1.30-3.17 μmol L-1 in winter, respectively) and low 87Sr/86Sr ratios (0.708686-0.709148 in summer and 0.708515-0.709305 in winter), which is similar to the characteristics of carbonate weathering. The Guijiang River has low Sr concentrations (0.124-1.098 μmol L-1) and high 87Sr/86Sr ratios (0.710558-0.724605), being characterized by silicate weathering. In the Xishui River catchment, chemical weathering rates in summer are far higher than those in winter, indicating significant influence of climate regime. However, slight differences of 87Sr/86Sr ratios between summer and winter show that influence of climate on Sr isotope is uncertainty owing to very similar Sr isotope values in silicate and carbonate bedrocks. As 87Sr/86Sr ratios in the Xishui River are lower than those in seawater, they will decrease 87Sr/86Sr ratio of seawater after transported into oceans. Previous studies also showed that some basaltic watersheds with extremely high chemical weathering rates reduced the seawater Sr isotope ratios. In other words, river catchments with high silicate weathering rates do not certainly transport highly radiogenic Sr into oceans. Therefore, it may be questionable that using the variations of seawater 87Sr/86Sr ratio to indicate the continental silicate weathering intensity. In the Guijiang River catchment, 87Sr/86Sr ratios of carbonate rocks and other sources (rainwater, domestic and industrial waste water, and agricultural fertilizer) are lower than 0.71. In comparison, some non-carbonate components, such as, sand rocks, mud rocks, shales, have relatively high Sr isotopic compositions. Moreover, granites accounted for only 5% of the

  19. Carbon isotopic composition in components of a mangrove ecosystem in the Sepetiba Bay, Rio de Janeiro, Brazil

    International Nuclear Information System (INIS)

    The carbon isotopic ratios (13C/12C) for various components of a mangrove ecosystem in the Sepetiba Bay, RJ, in order to evaluate the possibility of its use a tracer for organic matter in these environments are presented. The results showed consistent differences of (13C/12C) isotopic ratio between the organic matter from mangrove (+-26%0, PDB) and the one from marine origin (+-20%0, PDB). These results suggest that this ratio can be used as tracer of organic carbon in the studied environment. (Author)

  20. A Plant-Based Proxy for the Oxygen Isotope Ratio of Atmospheric Water Vapor

    Science.gov (United States)

    Helliker, B.

    2007-12-01

    Atmospheric water vapor is a major component of the global hydrological cycle, but the isotopic balance of vapor is largely unknown. It is shown here that the oxygen isotope ratio of leaf water in the epiphytic Crassulacean acid metabolism (CAM) plant Tillandsia usneoides (Spanish Moss) is controlled by the oxygen isotope ratio of atmospheric water vapor in both field and lab studies. Assuming that the leaf-water isotopic signature (and hence the atmospheric water vapor signature) is recorded in plant organic material, the atmospheric water vapor oxygen isotope ratios for Miami, Florida (USA) were reconstructed for several years from 1878 to 2005 using contemporary and herbarium specimens. T. usneoides ranges from Virginia, USA southwards through the tropics to Argentina, and the CAM epiphytic lifeform is widespread in other species. Therefore, epiphytes may be used to reconstruct the isotope ratio of atmospheric water for spatial scales that span over 60° of latitude and temporal scales that cover the last century of global temperature increase.

  1. Measurement of isotope ratios on transient signals by MC-ICP-MS

    International Nuclear Information System (INIS)

    Precise and accurate isotope ratio measurements are an important task in many applications such as isotope-dilution mass spectrometry, bioavailability studies, or the determination of isotope variations in geological or nuclear samples. The technique of MC-ICP-MS has attracted much attention because it permits the precise measurement of isotope compositions for a wide range of elements combined with excellent detection limits due to high ionisation efficiencies. However, the results are based mainly on measurements using continuous sample introduction. In the present study the determination of isotope ratios on various transient signals with a time duration of 30 to 60 s has been achieved by coupling high-performance liquid chromatography to a multicollector inductively coupled plasma mass spectrometer. In order to investigate the origin of ratio drifts across the transient signals for this hyphenated technique, measurements with the same standard solutions were also carried out using a flow-injection device for sample introduction. As a result of this application it could be concluded that the main source of the bias in the measured isotope ratios is within the ICP-MS instead of fractionation effects on the chromatographic column material. Preliminary studies on short transient signals of gaseous samples (dry plasma) showed a reverse fractionation effect compared with wet plasma conditions (flow injection and HPLC). (orig.)

  2. Stable isotope ratios of organic substances: sample preparation and mass spectrometric analysis

    International Nuclear Information System (INIS)

    The ratio of the stable isotopes (13 C/12 C, D/H, 15 N/14 N) in organic materials varies slightly around the average values as a results of isotopic fractionation during physical, chemical and biological processes. The differences between materials in the range of 1 to 10 parts per thousand in 13 C, 15 N, D content are often significant to biologists, and differences of 0.1 parts per thousand are often significant to climatologists of paleolithic and geochemists. In order to make use of these small, but significant variations, stable isotope ratios (13 C/12 C, D/H, 15 N/14 N) must be measured with extremely high precision. We developed the method capable of such high precision measurements. This method consists of conversion of organic samples to CO2, N2 and H2O by combustion in an excess of oxygen and the determination of stable isotope ratios by a dual-inlet gas isotope ratio mass spectrometer. The method was checked on methane and acetic acid with known isotopic composition. The reproducibility of the method was good and the precision was 0.1 o/oo. (authors)

  3. Analysis of the hydrogen and oxygen stable isotope ratios of beverage waters without prior water extraction using isotope ratio infrared spectroscopy.

    Science.gov (United States)

    Chesson, Lesley A; Bowen, Gabriel J; Ehleringer, James R

    2010-11-15

    Hydrogen (δ(2)H) and oxygen (δ(18)O) stable isotope analysis is useful when tracing the origin of water in beverages, but traditional analytical techniques are limited to pure or extracted waters. We measured the isotopic composition of extracted beverage water using both isotope ratio infrared spectroscopy (IRIS; specifically, wavelength-scanned cavity ring-down spectroscopy) and isotope ratio mass spectrometry (IRMS). We also analyzed beer, sodas, juices, and milk 'as is' using IRIS. For IRIS analysis, four sequential injections of each sample were measured and data were corrected for sample-to-sample memory using injections (a) 1-4, (b) 2-4, and (c) 3-4. The variation between δ(2)H and δ(18)O values calculated using the three correction methods was larger for unextracted (i.e., complex) beverages than for waters. The memory correction was smallest when using injections 3-4. Beverage water δ(2)H and δ(18)O values generally fit the Global Meteoric Water Line, with the exception of water from fruit juices. The beverage water stable isotope ratios measured using IRIS agreed well with the IRMS data and fit 1:1 lines, with the exception of sodas and juices (δ(2)H values) and beers (δ(18)O values). The δ(2)H and δ(18)O values of waters extracted from beer, soda, juice, and milk were correlated with complex beverage δ(2)H and δ(18)O values (r = 0.998 and 0.997, respectively) and generally fit 1:1 lines. We conclude that it is possible to analyze complex beverages, without water extraction, using IRIS although caution is needed when analyzing beverages containing sugars, which can clog the syringe and increase memory, or alcohol, a known spectral interference. PMID:20941769

  4. Determination of the sulfur isotope ratio in carbonyl sulfide using gas chromatography/isotope ratio mass spectrometry on fragment ions 32S+, 33S+, and 34S+.

    Science.gov (United States)

    Hattori, Shohei; Toyoda, Akari; Toyoda, Sakae; Ishino, Sakiko; Ueno, Yuichiro; Yoshida, Naohiro

    2015-01-01

    Little is known about the sulfur isotopic composition of carbonyl sulfide (OCS), the most abundant atmospheric sulfur species. We present a promising new analytical method for measuring the stable sulfur isotopic compositions (δ(33)S, δ(34)S, and Δ(33)S) of OCS using nanomole level samples. The direct isotopic analytical technique consists of two parts: a concentration line and online gas chromatography-isotope ratio mass spectrometry (GC-IRMS) using fragmentation ions (32)S(+), (33)S(+), and (34)S(+). The current levels of measurement precision for OCS samples greater than 8 nmol are 0.42‰, 0.62‰, and 0.23‰ for δ(33)S, δ(34)S, and Δ(33)S, respectively. These δ and Δ values show a slight dependence on the amount of injected OCS for volumes smaller than 8 nmol. The isotope values obtained from the GC-IRMS method were calibrated against those measured by a conventional SF6 method. We report the first measurement of the sulfur isotopic composition of OCS in air collected at Kawasaki, Kanagawa, Japan. The δ(34)S value obtained for OCS (4.9 ± 0.3‰) was lower than the previous estimate of 11‰. When the δ(34)S value for OCS from the atmospheric sample is postulated as the global signal, this finding, coupled with isotopic fractionation for OCS sink reactions in the stratosphere, explains the reported δ(34)S for background stratospheric sulfate. This suggests that OCS is a potentially important source for background (nonepisodic or nonvolcanic) stratospheric sulfate aerosols. PMID:25439590

  5. Isotope Ratio Analysis on Micron-Sized Particles in Complex Matrices by Laser Ablation - Absorption Ratio Spectrometry

    International Nuclear Information System (INIS)

    Laser ablation has been combined with dual tunable diode laser absorption spectrometry to measure 152Gd:160Gd isotope ratios in micron-size particles. The diode lasers are tuned to specific isotopes in two different atomic transitions at 405.9 nm (152Gd) and 413.4 nm (160Gd) and directed collinearly through the laser ablation plume, separated on a diffraction grating, and detected with photodiodes to monitor transient absorption signals on a shot-by-shot basis. The method has been characterized first using Gd metal foil and then with particles of GdCl3 x H20 as binary and ternary mixtures with 152Gd:160Gd isotope ratios ranging from 0.01 to 0.43. These particulate mixtures have been diluted with Columbia River sediment powder (SRM 4350B) to simulate environmental samples and we show the method is capable of detecting a few highly enriched particles in the presence of > 100-fold excess of low-enrichment particles, even when the Gd-bearing particles are a minor component (0.08%) in the SRM powder and widely dispersed (1178 particles detected in 800 000 ablation laser shots). The implications for monitoring 235U:238U enrichment ratios, as related to the nuclear industry, are discussed

  6. Isotope ratio analysis on micron-sized particles in complex matrices by Laser Ablation-Absorption Ratio Spectrometry

    International Nuclear Information System (INIS)

    Laser ablation has been combined with dual tunable diode laser absorption spectrometry to measure 152Gd:160Gd isotope ratios in micron-size particles. The diode lasers are tuned to specific isotopes in two different atomic transitions at 405.9 nm (152Gd) and 413.4 nm (160Gd) and directed collinearly through the laser ablation plume, separated on a diffraction grating, and detected with photodiodes to monitor transient absorption signals on a shot-by-shot basis. The method has been characterized first using Gd metal foil and then with particles of GdCl3.xH20 as binary and ternary mixtures with 152Gd:160Gd isotope ratios ranging from 0.01 to 0.43. These particulate mixtures have been diluted with Columbia River sediment powder (SRM 4350B) to simulate environmental samples and we show the method is capable of detecting a few highly-enriched particles in the presence of a >100-fold excess of low-enrichment particles, even when the Gd-bearing particles are a minor component (0.08%) in the SRM powder and widely dispersed (1178 particles detected in 800,000 ablation laser shots). The implications for monitoring 235U:238U enrichment ratios in airborne particle samples, as related to the nuclear industry, are discussed.

  7. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies

    Science.gov (United States)

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to ...

  8. Pliocene diatom and sponge spicule oxygen isotope ratios from the Bering Sea: isotopic offsets and future directions

    Directory of Open Access Journals (Sweden)

    A. M. Snelling

    2014-05-01

    Full Text Available Oxygen isotope analyses of different size fractions of Pliocene diatoms (δ18Odiatom from the Bering Sea show no evidence of an isotope offset and support the use of bulk diatom species samples for palaeoceanographic reconstructions. Additional samples containing concentrations of sponge spicules produce δ18O values several per mille lower than δ18Odiatom with a calculated mean offset of 3.6‰ ± 0.7. This difference is significantly greater than modern day variations in water δ18O through the regional water column. Despite the potential for oxygen isotope disequilibrium within δ18Osponge, there appears to be some similarity between δ18Osponge and a global stacked benthic δ18Oforam record. This highlights the potential for δ18Osponge in palaeoenvironmental research at sites where carbonates are not readily preserved.

  9. The magnesium isotope record of cave carbonate archives

    Directory of Open Access Journals (Sweden)

    S. Riechelmann

    2012-11-01

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

  10. The magnesium isotope record of cave carbonate archives

    Directory of Open Access Journals (Sweden)

    S. Riechelmann

    2012-05-01

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

  11. Absolute measurement of the isotopic ratio of a water sample with very low deuterium content

    International Nuclear Information System (INIS)

    The presence of H3+ ions which are indistinguishable from HD+ ions presents the principal difficulty encountered in the measurement of isotopic ratios of water samples with very low deuterium contents using a mass spectrometer. Thus, when the sample contains no deuterium, the mass spectrometer does not indicate zero. By producing, in situ, from the sample to be measured, water vapor with an isotopic ratio very close to zero using a small distilling column, this difficulty is overcome. This column, its operating parameters, as well as the way in which the measurements are made are described. An arrangement is employed in which the isotopic ratios can be measured with a sensitivity better than 0.01 x 10-6. The method is applied to the determination of the isotopic ratios of three low deuterium content water samples. The results obtained permit one to assign to the sample with the lowest deuterium content an absolute value equal to 1.71 ± 0.03 ppm. This water sample is a primary standard from which is determined the isotopic ratio of a natural water sample which serves as the laboratory standard. (author)

  12. Isotope ratio determination of lithium in acidic medium employing Li2BO2+ by TIMS

    International Nuclear Information System (INIS)

    Lithium isotopic composition data are required in many fields such as geochemistry, astrophysics, nuclear technology and biomedicine. Thermal Ionization Mass Spectrometry and in the recent years, MC-ICPMS are the two popular techniques used for obtaining information on 6Li/7Li isotopic ratio. Isotopic fractionation, especially for elements of low atomic masses like lithium degrades the precision of isotope ratios. A number of approaches using atomic (Li+) or molecular (Li2BO2+ or Li2F+) ion, single or multiple filament loading procedures have been followed to improve the precision of TIMS analysis. Existing sample preparation and filament loading techniques require modification depending on the history of the sample or treatment procedures followed. Our laboratory has followed the Li2BO2+ method using single filament assembly due to the reasonably high precision obtained at masses 55 to 57 as compared to Li+ at masses 6 and 7

  13. Research Progress of Series of Uranium Isotope Ratios Measured by AMS

    Institute of Scientific and Technical Information of China (English)

    LIN; De-yu; WANG; Chen; HUANG; Guo-rui; DONG; Ke-jun; HE; Ming; RUAN; Xiang-dong; WU; Shao-yong; ZHAO; Yong-gang; LI; Li-li; DOU; Liang; XIE; Lin-bo; WANG; Xiao-bo; YANG; Xu-ran; WANG; Xiao-ming; LAN; Xiao-xi; JIANG; Shan

    2012-01-01

    <正>The nuclear safeguards system which is used to monitor compliance with the Nuclear Non-proliferation Treaty relies to a significant degree on the analysis of environmental samples. Undeclared nuclear activities can be detected through determination of the isotopic ratios of uranium and plutonium in such samples. It is necessary to be able to measure the full suite of uranium isotopes (234U,

  14. Atmospheric circulation controls on the inter-annual variability in precipitation isotope ratio in Japan

    Directory of Open Access Journals (Sweden)

    N. Kurita

    2014-10-01

    Full Text Available This study explored the primary driver of variations of precipitation isotopes at multiple temporal scales (event, seasonal and inter-annual scales to provide a greater depth of interpretation for isotope proxy records in Japan. A one-year record of the isotopic composition of event-based precipitation at Nagoya in central Japan showed less seasonal variation, but there is large isotopic variability on a storm-to-storm basis. In the summer, southerly flows transport isotopically enriched moisture from subtropical marine regions with the result that the rainfall produced by the subtropical air, or warm rainfall, was relatively enriched in heavy isotopes in comparison with the other rainfall events. In the winter, storm tracks are the dominant driver of storm-to-storm isotopic variation, and relatively lower isotopic values occurred when northerly winds in association with extratropical cyclones passing off the south coast of Japan (Nangan cyclone brings cold precipitation. Using the historical 17 year record of monthly isotopes in precipitation at Tokyo station, we explored if the factors controlling event-scale isotopic variability can account for inter-annual isotopic variability. The relatively higher isotopes in summer precipitation were attributed to the higher contribution of the warm rainfall to the total summer precipitation. On the other hand, year-to-year variation of isotopic values in winter precipitation was negatively correlated with the relative ratio of the Nangan cyclone rainfall to the total winter precipitation. The 17 year precipitation history demonstrates that event-scale isotopic variability related to changes in meridional moisture transport is the primary driver of inter-annual isotopic variability in winter and summer precipitation. The meridional moisture transport to central Japan is likely linked to the activity of the western North Pacific subtropical high in summer and the intensity of the East Asian winter monsoon

  15. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry

    Science.gov (United States)

    Coplen, T.B.; Qi, H.

    2010-01-01

    An anomalous stable hydrogen isotopic fractionation of 4 ??? in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) ??2H reproducibility (1?? standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1 ??? to 0.58 ???. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen. ?? This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society.

  16. A study of isotope ratio measurement by inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    The measurement of isotopic ratios by inductively coupled plasma mass spectrometry (ICP-MS) has the benefits of ionising all metallic elements, simplifying sample preparation and reducing analysis time, when compared with thermal ionisation mass spectrometry (TIMS). However, the use of ICP-MS in isotopic ratio studies has been somewhat restricted by its failure to offer the precision and accuracy required by a variety of applications. The precision achievable by ICP-MS, typically 0.2 to 0.3% RSD, for isotopic ratios, has generally been regarded as being primarily limited by instrumental instability. An investigation of the sources of instrumental noise in ICP-MS has been undertaken, utilising noise spectral analysis as a diagnostic aid. Study of parametric variation upon noise production has identified the methods by which modulation of the ion signal occurs. Noise spectral analysis has allowed an understanding of the limitations imposed upon measurement precision by the various contributing noise sources to be established. (author)

  17. ­­A Clumped Isotope Calibration for Terrestrial Microbial Carbonates

    Science.gov (United States)

    Petryshyn, V. A.; Mering, J. A.; Mitsunaga, B. A.; Eagle, R.; Dunbar, R. B.; Bhattacharya, A.; Tripati, A.

    2014-12-01

    Accurate terrestrial paleotemperature records are key pieces of information in the paleoenvironmental reconstruction of Earth history. These records aid in building reliable climate models and help scientists understand the links between continental and oceanic climate data. Many different types of analyses are used to estimate terrestrial climate shifts, including leaf margin analysis, palynology, glacial deposits, elemental ratios, organic geochemistry, and stable isotopes of lacustrine deposits. Here we report a carbonate clumped isotope calibration for microbial carbonates. Application of the clumped isotope paleothermometer can potentially provide a direct temperature measurement of the water at the time of carbonate formation. Although different calibrations of the paleothermometer have been published for both inorganic and biotic carbonate minerals, the effects of clumping in microbialites (structures built under the influence of microbial activity) have not yet been quantified. Lacustrine microbialites present a potentially large, untapped archive of terrestrial climate data, however they are not strictly biotic or abiotic, but bio-induced carbonate, meaning that organisms (such as photosynthetic bacteria) influence but do not directly control precipitation. We have measured modern microbialites from multiple lacustrine sites and will report a comparison of these results to known water temperatures. Additionally we will compare lacustrine samples to marine microbialites (e.g., samples from Shark Bay) to assess potential differences between lacustrine and marine intertidal environments on clumped isotope compositions.

  18. Temperature dependence of carbon isotope fractionation in CAM plants

    Energy Technology Data Exchange (ETDEWEB)

    Deleens, E.; Treichel, I.; O' Leary, M.H.

    1985-09-01

    The carbon isotope fractionation associated with nocturnal malic acid synthesis in Kalanchoe daigremontiana and Bryophyllum tubiflorum was calculated from the isotopic composition of carbon-4 of malic acid, after appropriate corrections. In the lowest temperature treatment (17/sup 0/C nights, 23/sup 0/C days), the isotope fractionation for both plants is -4% per thousand (that is, malate is enriched in /sup 13/C relative to the atmosphere). For K. daigremontiana, the isotope fractionation decreases with increasing temperature, becoming approximately 0% per thousand at 27/sup 0/C/33/sup 0/C. Detailed analysis of temperature effects on the isotope fractionation indicates that stomatal aperture decreases with increasing temperature and carboxylation capacity increases. For B. tubiflorum, the temperature dependence of the isotope fractionation is smaller and is principally attributed to the normal temperature dependences of the rates of diffusion and carboxylation steps. The small change in the isotopic composition of remaining malic acid in both species which is observed during deacidification indicates that malate release, rather than decarboxylation, is rate limiting in the deacidification process. 28 references, 1 figure, 4 tables.

  19. The Methane to Carbon Dioxide Ratio Produced during Peatland Decomposition and a Simple Approach for Distinguishing This Ratio

    Science.gov (United States)

    Chanton, J.; Hodgkins, S. B.; Cooper, W. T.; Glaser, P. H.; Corbett, J. E.; Crill, P. M.; Saleska, S. R.; Rich, V. I.; Holmes, B.; Hines, M. E.; Tfaily, M.; Kostka, J. E.

    2014-12-01

    Peatland organic matter is cellulose-like with an oxidation state of approximately zero. When this material decomposes by fermentation, stoichiometry dictates that CH4 and CO2 should be produced in a ratio approaching one. While this is generally the case in temperate zones, this production ratio is often departed from in boreal peatlands, where the ratio of belowground CH4/CO2 production varies between 0.1 and 1, indicating CO2 production by a mechanism in addition to fermentation. The in situ CO2/CH4 production ratio may be ascertained by analysis of the 13C isotopic composition of these products, because CO2 production unaccompanied by methane production produces CO2 with an isotopic composition similar to the parent organic matter while methanogenesis produces 13C depleted methane and 13C enriched CO2. The 13C enrichment in the subsurface CO2 pool is directly related to the amount of if formed from methane production and the isotopic composition of the methane itself. Excess CO2 production is associated with more acidic conditions, Sphagnum vegetation, high and low latitudes, methane production dominated by hydrogenotrophic methane production, 13C depleted methane, and generally, more nutrient depleted conditions. Three theories have been offered to explain these observations— 1) inhibition of acetate utilization, acetate build-up and diffusion to the surface and eventual aerobic oxidation, 2) the use of humic acids as electron acceptors, and the 3) utilization of organic oxygen to produce CO2. In support of #3, we find that 13C-NMR, Fourier transform infrared (FT IR) spectroscopy, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) clearly show the evolution of polysaccharides and cellulose towards more decomposed humified alkyl compounds stripped of organic oxygen utilized to form CO2. Such decomposition results in more negative carbon oxidation states varying from -1 to -2. Coincident with this reduction in oxidation state, is the

  20. Carbon emissions intensity ratio: an indicator for an improved carbon labelling scheme

    International Nuclear Information System (INIS)

    This letter proposes a new carbon labelling scheme to improve the visibility of products’ life cycle carbon emissions (sometimes defined as carbon footprint). This approach starts by normalizing carbon emissions data on a common scale of ‘carbon emissions intensity’, and a new indicator ‘carbon emissions intensity ratio’ is generated based upon its ratio to the annual national greenhouse gas emission per gross domestic product. Five ranges (extremely low, low, medium, high and extremely high) are used to represent the level of carbon emissions intensity ratio by a simple diagram with colour gradation. Case examples are presented, in which the carbon emissions intensity ratios of various selected products, both distinct and related, are calculated and compared. The limitations of this approach are then discussed, laying a foundation for further work. (letter)

  1. Carbon and hydrogen isotopic compositions of New Zealand geothermal gases

    International Nuclear Information System (INIS)

    Carbon and hydrogen isotopic compositions are reported for methane, hydrogen and carbon dioxide from four New Zealand geothermal areas; Ngawha, Wairakei, Broadlands and Tikitere. Carbon-13 contents are between -24.4 and -29.5 per mille (PDB) for methane, and between -3.2 and -9.1 per mille for carbon dioxide. Deuterium contents are between -142 and -197 per mille (SMOW) for methane and between -310 and -600 per mille for hydrogen. The different areas have different isotopic compositions with some general relationships to reservoir temperature. The isotopic exchange of hydrogen with water indicates acceptable reservoir temperatures of 180 to 260 deg C from most spring samples but often higher than measured temperatures in well samples. Indicated temperatures assuming 13C equilibria between CH4 and CO2 are 100 to 200 deg C higher than measured maxima. This difference may be due to partial isotopic equilibration or may reflect the origin of the methane. Present evidence cannot identify whether the methane is primordial, or from decomposing sediments or from reduction of magmatic CO2. The isotopic equilibria between CH4, CO2, H2 and H2O are reviewed and a new semiempirical temperature scale proposed for deuterium exchange between methane and water. (author)

  2. Lithologically inherited variation in Pb isotope ratios in sedimentary soils in The Netherlands

    International Nuclear Information System (INIS)

    Highlights: • We present a Pb isotope survey of ∼350 rural subsoils covering the Netherlands. • The great majority (∼90%) of the subsoils shows no evidence of enhanced Pb content. • The lithologies – sand, clay, peat and loess – have distinct Pb isotope signatures. • The observed variation is explained by the textural and mineralogical variation. • The Al and Zr content are predictors for the observed Pb isotope variability. - Abstract: Knowledge on the lithologically inherited variation in present day Pb isotope ratios in soils is remarkably limited. Such information is essential to determine the anthropogenic Pb fraction and anthropogenic Pb sources in Pb-polluted soils. This study presents results of a survey of subsoil samples from approximately 350 rural locations covering the entire Netherlands, for which the bulk geochemical and Pb isotope composition was determined. The sample density was approximately 1 site per 70 km2. The aim was to establish a geochemical reference for the lithologically inherited variation in Pb isotope ratios in Dutch soils based on the subsoil samples, with which to compare the topsoils (companion paper in this journal issue). The lithologically inherited variation in Pb isotope ratios of the subsoils in The Netherlands is established at 1.175–1.221, 2.441–2.494 and 0.478–0.492 for 206Pb/207Pb, 207Pb/208Pb and 206Pb/208Pb respectively. The four main lithologies distinguished, sand, clay, peat and loess, have distinct Pb isotope signatures. No significant difference in isotope signature was found between marine and fluviatile clays. Multiple regression analysis established that the observed variation can be primarily explained by the textural and mineralogical variation within Dutch subsoils, with Al and Zr content representing useful predictors for the observed Pb isotope variability. Clay soils are characterised by a radiogenic Pb isotope signature that is notably low in 207Pb. Soils with a high Zr content

  3. Amino acid delta13C analysis of hair proteins and bone collagen using liquid chromatography/isotope ratio mass spectrometry: paleodietary implications from intra-individual comparisons

    DEFF Research Database (Denmark)

    Raghavan, Maanasa; McCullagh, James S O; Lynnerup, Niels;

    2010-01-01

    We report a novel method for the chromatographic separation and measurement of stable carbon isotope ratios (delta(13)C) of individual amino acids in hair proteins and bone collagen using the LC-IsoLink system, which interfaces liquid chromatography (LC) with isotope ratio mass spectrometry (IRMS......). This paper provides baseline separation of 15 and 13 of the 18 amino acids in bone collagen and hair proteins, respectively. We also describe an approach to analysing small hair samples for compound-specific analysis of segmental hair sections. The LC/IRMS method is applied in a historical context by...

  4. Carbon isotope fractionation of amino acids in fish muscle reflects biosynthesis and isotopic routing from dietary protein.

    Science.gov (United States)

    McMahon, Kelton W; Fogel, Marilyn L; Elsdon, Travis S; Thorrold, Simon R

    2010-09-01

    1. Analysis of stable carbon isotopes is a valuable tool for studies of diet, habitat use and migration. However, significant variability in the degree of trophic fractionation (Delta(13)C(C-D)) between consumer (C) and diet (D) has highlighted our lack of understanding of the biochemical and physiological underpinnings of stable isotope ratios in tissues. 2. An opportunity now exists to increase the specificity of dietary studies by analyzing the delta(13)C values of amino acids (AAs). Common mummichogs (Fundulus heteroclitus, Linnaeus 1766) were reared on four isotopically distinct diets to examine individual AA Delta(13)C(C-D) variability in fish muscle. 3. Modest bulk tissue Delta(13)C(C-D) values reflected relatively large trophic fractionation for many non-essential AAs and little to no fractionation for all essential AAs. 4. Essential AA delta(13)C values were not significantly different between diet and consumer (Delta(13)C(C-D) = 0.0 +/- 0.4 per thousand), making them ideal tracers of carbon sources at the base of the food web. Stable isotope analysis of muscle essential AAs provides a promising tool for dietary reconstruction and identifying baseline delta(13)C values to track animal movement through isotopically distinct food webs. 5. Non-essential AA Delta(13)C(C-D) values showed evidence of both de novo biosynthesis and direct isotopic routing from dietary protein. We attributed patterns in Delta(13)C(C-D) to variability in protein content and AA composition of the diet as well as differential utilization of dietary constituents contributing to the bulk carbon pool. This variability illustrates the complicated nature of metabolism and suggests caution must be taken with the assumptions used to interpret bulk stable isotope data in dietary studies. 6. Our study is the first to investigate the expression of AA Delta(13)C(C-D) values for a marine vertebrate and should provide for significant refinements in studies of diet, habitat use and migration using

  5. Measurement of the concentration ratio for 13N and 12N isotopes at atmospheric pressure by carbon dioxide absorption of diode laser radiation at ∼2 μm

    International Nuclear Information System (INIS)

    The ratio of 12NO2 and 13CO2 concentrations in the human exhaled air is measured by the method of diode laser spectroscopy using a three-channel optical scheme and multipass cell. Unlike the previous measurements in the spectral range of ∼4.3 μm with a resolved rotational structure at low pressure of selected samples, the present measurements are performed in the range of ∼2 μm, in which weaker absorption bands of CO2 reside. In this case, it is possible to employ lasers and photodetectors operating at room temperature. The thorough simulation of the spectrum with collisional broadening of lines and employment of regression analysis allow one to take measurements at atmospheric pressure with the accuracy of ∼0.04%, which satisfies the requirements to medical diagnostics of ulcers. (laser spectroscopy)

  6. On the cross-sensitivity between water vapor mixing ratio and stable isotope measurements of in-situ analyzers

    KAUST Repository

    Parkes, Stephen

    2015-04-01

    In recent years there has been an increasing amount of water vapor stable isotope data collected using in-situ instrumentation. A number of papers have characterized the performance of these in-situ analyzers and suggested methods for calibrating raw measurements. The cross-sensitivity of the isotopic measurements on the mixing ratio has been shown to be a major uncertainty and a variety of techniques have been suggested to characterize this inaccuracy. However, most of these are based on relating isotopic ratios to water vapor mixing ratios from in-situ analyzers when the mixing ratio is varied and the isotopic composition kept constant. An additional correction for the span of the isotopic ratio scale is then applied by measuring different isotopic standards. Here we argue that the water vapor cross-sensitivity arises from different instrument responses (span and offset) of the parent H2O isotope and the heavier isotopes, rather than spectral overlap that could cause a true variation in the isotopic ratio with mixing ratio. This is especially relevant for commercial laser optical instruments where absorption lines are well resolved. Thus, the cross-sensitivity determined using more conventional techniques is dependent on the isotopic ratio of the standard used for the characterization, although errors are expected to be small. Consequently, the cross-sensitivity should be determined by characterizing the span and zero offset of each isotope mixing ratio. In fact, this technique makes the span correction for the isotopic ratio redundant. In this work we model the impact of changes in the span and offset of the heavy and light isotopes and illustrate the impact on the cross-sensitivity of the isotopic ratios on water vapor. This clearly shows the importance of determining the zero offset for the two isotopes. The cross-sensitivity of the isotopic ratios on water vapor is then characterized by determining the instrument response for the individual isotopes for a

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

    Science.gov (United States)

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

    2008-12-01

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

  8. Soil organic carbon assessments in cropping systems using isotopic techniques

    Science.gov (United States)

    Martín De Dios Herrero, Juan; Cruz Colazo, Juan; Guzman, María Laura; Saenz, Claudio; Sager, Ricardo; Sakadevan, Karuppan

    2016-04-01

    Introduction of improved farming practices are important to address the challenges of agricultural production, food security, climate change and resource use efficiency. The integration of livestock with crops provides many benefits including: (1) resource conservation, (2) ecosystem services, (3) soil quality improvements, and (4) risk reduction through diversification of enterprises. Integrated crop livestock systems (ICLS) with the combination of no-tillage and pastures are useful practices to enhance soil organic carbon (SOC) compared with continuous cropping systems (CCS). In this study, the SOC and its fractions in two cropping systems namely (1) ICLS, and (2) CCS were evaluated in Southern Santa Fe Province in Argentina, and the use of delta carbon-13 technique and soil physical fractionation were evaluated to identify sources of SOC in these systems. Two farms inside the same soil cartographic unit and landscape position in the region were compared. The ICLS farm produces lucerne (Medicago sativa Merrill) and oat (Avena sativa L.) grazed by cattle alternatively with grain summer crops sequence of soybean (Glicine max L.) and corn (Zea mays L.), and the farm under continuous cropping system (CCS) produces soybean and corn in a continuous sequence. The soil in the area is predominantly a Typic Hapludoll. Soil samples from 0-5 and 0-20 cm depths (n=4) after the harvest of grain crops were collected in each system and analyzed for total organic carbon (SOC, 0-2000 μm), particulate organic carbon (POC, 50-100 μm) and mineral organic carbon (MOC, <50 μm). Delta carbon-13 was determined by isotopic ratio mass spectrometry. In addition, a site with natural vegetation (reference site, REF) was also sampled for delta carbon-13 determination. ANOVA and Tukey statistical analysis were carried out for all data. The SOC was higher in ICLS than in CCS at both depths (20.8 vs 17.7 g kg-1 for 0-5 cm and 16.1 vs 12.7 g kg-1 at 0-20 cm, respectively, P<0.05). MOC was

  9. Tracing the transport of anthropogenic lead in the atmosphere and in soils using isotopic ratios

    Science.gov (United States)

    Erel, Yigal; Veron, Alain; Halicz, Ludwik

    1997-11-01

    The isotopic composition of lead in aerosols and soils in Israel is used to characterize the sources of anthropogenic lead in the region, to ascertain the isotopic composition of natural, rock-derived lead in specific areas, and to determine rates of anthropogenic lead migration in soils. The isotopic composition of lead currently emitted from cars in Israel ( 206Pb /207Pb = 1.115 ± 2 ) is controlled by alkyl-lead produced in France and Germany. In addition to petrol-lead, two more sources of anthropogenic lead can be detected in sampled aerosols: the first one has low concentrations of lead (˜4 ng/m 3) and 206Pb /207Pb ˜ 1.157 , and is most likely lead, emitted in Turkey, that traveled across the eastern Mediterranean basin; the second type of aerosols contains a mixture of lead emitted in several countries including Turkey, Greece, and Ukraine ( 206Pb /207Pb value of 1.155-1.160; [Pb] ˜ 20-30 ng/m 3). Anthropogenic lead is more accessible for acid leaching than natural lead, therefore, it is more labile in the soil. The isotopic composition of lead in the acid-leached fraction of near-road soil profiles record the histor of alkyl-lead emission in the country. Based on changes in the isotopic composition of lead with soil depth, it is estimated that anthropogenic lead migrates into the soil at approximately 0.5 cm/y. A soil profile from a relatively remote area is less contaminated by anthropogenic lead and displays a different distribution of lead isotopic values with depth. The isotopic composition of lead suggests that natural lead in soils developed on carbonate bedrock is derived from clays, either from the rock-esidue (the clay fraction in the carbonate bedrock), or from airborne clay, but not from lead released from the carbonate fraction in the rock.

  10. Aptian Carbon Isotope Stratigraphy in Sierra del Rosario, Northeastern Mexico

    Science.gov (United States)

    Barragan-Manzo, R.; Moreno-Bedmar, J.; Nuñez, F.; Company, M.

    2013-05-01

    In most recent years Aptian carbon isotope stratigraphy has been widely studied in Europe where isotopic stages have been developed to correlate global events. Two negative excursions have been recorded in the Lower Aptian, the older is OAE 1a in the middle part, and a younger negative excursion labeled "Aparein level", which occurs in the uppermost part of the Lower Aptian. In Mexico previous works reported a carbon isotope negative excursion in the lowermost part of the La Peña Formation that was assigned to the onset of Oceanic Anoxic Event 1a (=OAE 1a). In this work we study the isotopic record of the δ13Ccarb of 32 bulk rock samples of limestone from the uppermost part of the Cupido Formation and the lower part of the La Peña Formation at the Francisco Zarco Dam Section (=FZD), Durango State, northeastern Mexico. The isotopic data are calibrated using the latest ammonite biostratigraphic biozonation of the Aptian. This age calibration allows us to make a precise correlation between the carbon isotopic record of Mexico and several European sections (e.g. Spain and France). In the studied Francisco Zarco Dam section we recognize a negative carbon isotopic excursion in the Dufrenoyia justinae ammonite Zone that corresponds to the "Aparein level", which we correlate using the ammonite zonation of others European sections (Figure 1). This correlation allows us to see how the negative excursion that characterizes the "Aparein level" is consistent with the C7 segment. Thus, our recent stratigraphic study allows us to conclude that the ammonite record in the lowermost part of the La Peña Formation is regionally isochronous, and correlates with the Dufrenoyia justinae Zone and Lower Aptian isotope interval C7. In agreement to these biostratigraphic data, the supposed record of the OAE 1a in the lowermost part of the La Peña Formation is not correct, and the carbon isotope negative excursion must be assigned to the younger event "Aparein level". Taking this into

  11. Aircraft measurements of the concentrations of CO2, CH4, N2O, and CO and the carbon and oxygen isotopic ratios of CO2 in the troposphere over Russia

    Science.gov (United States)

    Nakazawa, Takakiyo; Sugawara, Satoshi; Inoue, Gen; Machida, Toshinobu; Makshyutov, Shamil; Mukai, Hitoshi

    1997-02-01

    About 370 air samples were collected using aircraft in the troposphere over Russia in the summers of 1992, 1993, and 1994. These were then analyzed for the CO2, CH4, N2O and CO concentrations, as well as for δ13C and δ18O of CO2. Measured vertical profiles of tropospheric CO2 showed that the concentration increased with height over all locations. In the lower troposphere over the wetland and taiga regions, extremely low CO2 concentrations of 335-345 parts per million by volume (ppmv) were often observed. Measured values of δ13C and the CO2 concentration were negatively correlated with each other, the rate of change in δ13C with respect to the CO2 concentration being about -0.05‰/ppmv. This implies that the variations in the CO2 concentration observed over Russia in the summer are primarily caused by terrestrial biospheric activities. In the middle and upper troposphere, the CO2 concentration and δ13C showed systematic differences between each other in 1992, 1993, and 1994, probably due to their secular changes. The δ18O and CO2 observed in the lowest part of the troposphere over east and west Siberia were also negatively correlated with each other, with the rate of change in δ18O with respect to CO2 estimated to be about -0.1 l‰/ppmv. This relation may be caused by isotopic equilibrium of oxygen in CO2 with soil water through respiration of living plants and decomposition of organic matter and with chloroplast water in leaves through photosynthesis of living plants. In contrast to CO2, the CH4 concentration decreased with height. Extremely high CH4 concentrations were observed over the west Siberian lowland, owing to a large amount of CH4 emitted from wetlands. The N2O concentrations were fairly constant through the troposphere over all locations covered by this study, with an average value of about 311 parts per billion by volume (ppbv). The CO concentrations also showed vertical profiles, with a small gradient over natural wetlands, taiga, and tundra

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

    Directory of Open Access Journals (Sweden)

    M. Saurer

    2008-11-01

    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, 47% at the motorway site and 28% at the rural site based on the isotope mass balance. As this analysis showed a strong sensitivity towards the pure source isotope values, we additionally applied a combined CO/NOx-isotope model for verification. Here, we separated the CO emissions into different sources based on different 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 δ18O-values of CO was found (r=0

  13. Using a laser-based CO2 carbon isotope analyser to investigate gas transfer in geological media

    International Nuclear Information System (INIS)

    CO2 stable carbon isotopes are very attractive in environmental research to investigate both natural and anthropogenic carbon sources. Laser-based CO2 carbon isotope analysis provides continuous measurement at high temporal resolution and is a promising alternative to isotope ratio mass spectrometry (IRMS). We performed a thorough assessment of a commercially available CO2 Carbon Isotope Analyser (CCIA DLT-100, Los Gatos Research) that allows in situ measurement of C-13 in CO2. Using a set of reference gases of known CO2 concentration and carbon isotopic composition, we evaluated the precision, long-term stability, temperature sensitivity and concentration dependence of the analyser. Despite good precision calculated from Allan variance (5.0 ppm for CO2 concentration, and 0.05 per thousand for δC-13 at 60 s averaging), real performances are altered by two main sources of error: temperature sensitivity and dependence of C-13 on CO2 concentration. Data processing is required to correct for these errors. Following application of these corrections, we achieve an accuracy of 8.7 ppm for CO2 concentration and 1.3 per thousand for δC-13, which is worse compared to mass spectrometry performance, but still allowing field applications. With this portable analyser we measured CO2 flux degassed from rock in an underground tunnel. The obtained carbon isotopic composition agrees with IRMS measurement, and can be used to identify the carbon source. (authors)

  14. Determination of the isotopic ratio 235U/238U in UF6 using quadrupole mass spectrometry

    International Nuclear Information System (INIS)

    In this work measurements of isotope ratios 235U / 23'8U in uranium hexafluoride are carried out using a quadrupole mass spectrometer. The operational parameters, which affect the final precision of the results, are standardized. Optimized procedures for the preparation of uranium hexafluoride samples by fluorination of uranium oxides using cobalt trifluoride method are established. Careful attention is given to the process of purification of uranium hexafluoride samples by fractional distillation. Adequate statistical methods for analysing the results obtained for single ratio measurements as well as the ratio ' of isotopic ratios of sample and standard ar.e developed. A precision of about 10-4 for single ratio measurements and accuracy of about 0,3% for the ratio of sample and standard ratios are obtained. These results agree with the values which have been obtained using magnetic mass spectrometers. The procedures and methods established in this work can be employed in the systematic uranium isotope analysis in UF6 form. (author)

  15. Stable isotope ratio mass spectrometry of nanogram quantities of boron and sulfur

    Science.gov (United States)

    Wieser, Michael Eugene

    1998-09-01

    Instrumentation and analytical techniques were developed to measure isotope abundances from nanograms of sulfur and boron. Sulfur isotope compositions were determined employing continuous flow isotope ratio mass spectroscopy (CF-IRMS) procedures and AsS+ thermal ionization mass spectrometry techniques (AsS+-TIMS). Boron isotope abundances were determined by BO2/sp--TIMS. CF-IRMS measurements realized δ34S values from 10 μg sulfur with precisions of ±0.3/perthous. To extend sulfur isotope measurements to much smaller samples, a TIMS procedure was developed to measure 75As32S+ and 75As34S+ at masses 108 and 109 from 200 ng S on a Finnigan MAT 262 with an ion counter. This is possibly the smallest amount of sulfur which has been successfully analyzed isotopically. The internal precision of 32S/34S ratios measured by AsS+-TIMS was better than ±0.15 percent. δ34S-values calculated relative to the measured 32S/34S value of an IAEA AG2S standard (S-1) agreed with those determined by CF-IRMS to within ±3/perthous. The increasing sensitivity of S-isotope analyses permits hiterto impossible investigations e.g. sulfur in tree rings and ice cores. Boron isotope abundances were measured as BO2/sp- from 50 ng B using an older thermal ionization mass spectrometer which had been extensively upgraded including the addition of computer control electronics, sensitive ion current amplification and fiber optic data bus. The internal precisions of the measured 11B/10B ratios were ±0.15 percent and the precisions of δ11B values calculated relative to the accepted international standard (SRM-951) were ±3/perthous. Two applications of boron isotope abundance variations were initiated (1) ground waters of Northern Alberta and (2) coffee beans in different regions of the world. In the first it was demonstrated that boron isotopes could be used to trace boron released during steam injection of oil sands into the surrounding environment. Data from the second study suggest that boron

  16. Uranium Isotopic Ratio Measurements of U3O8 Reference Materials by Atom Probe Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Fahey, Albert J.; Perea, Daniel E.; Bartrand, Jonah AG; Arey, Bruce W.; Thevuthasan, Suntharampillai

    2016-01-01

    We report results of measurements of isotopic ratios obtained with atom probe tomography on U3O8 reference materials certified for their isotopic abundances of uranium. The results show good agreement with the certified values. High backgrounds due to tails from adjacent peaks complicate the measurement of the integrated peak areas as well as the fact that only oxides of uranium appear in the spectrum, the most intense of which is doubly charged. In addition, lack of knowledge of other instrumental parameters, such as the dead time, may bias the results. Isotopic ratio measurements can be performed at the nanometer-scale with the expectation of sensible results. The abundance sensitivity and mass resolving power of the mass spectrometer are not sufficient to compete with magnetic-sector instruments but are not far from measurements made by ToF-SIMS of other isotopic systems. The agreement of the major isotope ratios is more than sufficient to distinguish most anthropogenic compositions from natural.

  17. Proportions of convective and stratiform precipitation revealed in water isotope ratios

    Science.gov (United States)

    Aggarwal, Pradeep K.; Romatschke, Ulrike; Araguas-Araguas, Luis; Belachew, Dagnachew; Longstaffe, Frederick J.; Berg, Peter; Schumacher, Courtney; Funk, Aaron

    2016-08-01

    Tropical and midlatitude precipitation is fundamentally of two types, spatially limited and high-intensity convective or widespread and lower-intensity stratiform, owing to differences in vertical air motions and microphysical processes governing rain formation. These processes are difficult to observe or model and precipitation partitioning into rain types is critical for understanding how the water cycle responds to changes in climate. Here, we combine two independent data sets--convective and stratiform precipitation fractions, derived from the Tropical Rainfall Measuring Mission satellite or synoptic cloud observations, and stable isotope and tritium compositions of surface precipitation, derived from a global network--to show that isotope ratios reflect rain type proportions and are negatively correlated with stratiform fractions. Condensation and riming associated with boundary layer moisture produces higher isotope ratios in convective rain, along with higher tritium when riming in deep convection occurs with entrained air at higher altitudes. On the basis of our data, stable isotope ratios can be used to monitor changes in the character of precipitation in response to periodic variability or changes in climate. Our results also provide observational constraints for an improved simulation of convection in climate models and a better understanding of isotope variations in proxy archives, such as speleothems and tropical ice.

  18. Genuineness assessment of mandarin essential oils employing gas chromatography-combustion-isotope ratio MS (GC-C-IRMS).

    Science.gov (United States)

    Schipilliti, Luisa; Tranchida, Peter Quinto; Sciarrone, Danilo; Russo, Marina; Dugo, Paola; Dugo, Giovanni; Mondello, Luigi

    2010-03-01

    Cold-pressed mandarin essential oils are products of great economic importance in many parts of the world and are used in perfumery, as well as in food products. Reconstituted mandarin oils are easy to find on the market; useful information on essential oil authenticity, quality, extraction technique, geographic origin and biogenesis can be attained through high-resolution GC of the volatile fraction, or enantioselective GC, using different chiral stationary phases. Stable isotope ratio analysis has gained considerable interest for the unveiling of citrus oil adulteration, detecting small differences in the isotopic carbon composition and providing plenty of information concerning the discrimination among products of different geographical origin and the adulteration of natural essential oils with synthetic or natural compounds. In the present research, the authenticity of several mandarin essential oils was assessed through the employment of GC hyphenated to isotope ratio MS, conventional GC flame ionization detector, enantioselective GC and HPLC. Commercial mandarin oils and industrial natural (declared as such) mandarin essential oils, characterized by different harvest periods and geographic origins, were subjected to analysis. The results attained were compared with those of genuine cold-pressed Italian mandarin oils, obtained during the 2008-2009 harvest season. PMID:20112303

  19. ISOTOPIC RATIOS IN TITAN's METHANE: MEASUREMENTS AND MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Nixon, C. A.; Achterberg, R. K. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Temelso, B. [Dean' s Office, College of Arts and Sciences, Department of Chemistry, Bucknell University, Lewisburg, PA 17837 (United States); Vinatier, S.; Bezard, B.; Coustenis, A. [LESIA, Observatoire de Paris, CNRS, 5 Place Jules Janssen, 92195 Meudon Cedex (France); Teanby, N. A. [School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen' s Road, Bristol BS8 1RJ (United Kingdom); Mandt, K. E. [Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228 (United States); Sherrill, C. D. [School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA 30332-0400 (United States); Irwin, P. G. J. [Atmospheric, Oceanic and Planetary Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom); Jennings, D. E.; Romani, P. N.; Flasar, F. M. [Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-04-20

    The existence of methane in Titan's atmosphere ({approx}6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of {approx}20 Myr. In this paper, we examine the clues available from isotopic ratios ({sup 12}C/{sup 13}C and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH{sub 4} collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: {sup 13}CH{sub 4}, {sup 12}CH{sub 3}D, and {sup 13}CH{sub 3}D. From these we compute estimates of {sup 12}C/{sup 13}C = 86.5 {+-} 8.2 and D/H = (1.59 {+-} 0.33) Multiplication-Sign 10{sup -4}, in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH{sub 4} + C{sub 2}H {yields} CH{sub 3} + C{sub 2}H{sub 2}. Using these new measurements and predictions we proceed to model the time evolution of {sup 12}C/{sup 13}C and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model 1 (no resupply of CH{sub 4}), we find that the present-day {sup 12}C/{sup 13}C implies that the CH{sub 4} entered the atmosphere 60-1600 Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently-most likely less than 10 Myr ago-if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing. We conclude by discussing how these findings may be combined with other evidence to constrain the overall

  20. Novel quantum-cascade laser based spectrometer for high precision isotopic ratio measurements of atmospheric CO2

    International Nuclear Information System (INIS)

    Full text: Continuous and in-situ monitoring of the isotope content of atmospheric carbon dioxide is of prime interest in the biosphere-atmosphere exchange research. We present the design and laboratory results of a compact mid-IR spectrometer developed for such purposes using a pulsed quantum cascade laser (QCL) from Alpes Lasers operating at 4.3 μm. Employing thermoelectrically cooled (TEC) components for both the IR laser light source and detector, the instrument can operate in a complete cryogenic-free mode that greatly facilitates field applications. Furthermore, the carefully selected spectral range in the ν3 ro-vibrational band of CO2 allows for simultaneous concentration measurements of the three main stable carbon dioxide isotopologues (16O12C16O, 16O13C16O and 18O12C16O) in ambient air. The isotopic ratio measurement is performed using differential absorption spectroscopy. A dual multipass-cell arrangement is used to analyze the difference between the sample spectra and the simultaneously acquired reference spectra. This approach significantly improves the spectrometer performance due to the cancellation of correlated noise components specific to this method. The instrument precision has been evaluated using the Allan variance technique. The 13CO2/12CO2 ratio has a 1 s standard deviation of 0.6 o/oo, while the variance minimum at 430 s corresponds to a minimum σAllan of 0.04 o/oo. This clearly demonstrates the feasibility of high precision in-situ isotope ratio measurements by the above mentioned optical technique. Additional efforts for the development of an adequate calibration method and the integration of optimized TEC detectors, which are expected to give even better performance, are currently undertaken. (author)

  1. Spectral analysis software improves confidence in plant and soil water stable isotope analyses performed by isotope ratio infrared spectroscopy (IRIS).

    Science.gov (United States)

    West, A G; Goldsmith, G R; Matimati, I; Dawson, T E

    2011-08-30

    Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isotope analysis. Here we report two independent tests of this post-processing spectral analysis software on two IRIS systems, OA-ICOS (Los Gatos Research Inc.) and WS-CRDS (Picarro Inc.). Following a similar methodology to a previous study, we cryogenically extracted plant leaf water and soil water and measured the δ(2)H and δ(18)O values of identical samples by isotope ratio mass spectrometry (IRMS) and IRIS. As an additional test, we analyzed plant stem waters and tap waters by IRMS and IRIS in an independent laboratory. For all tests we assumed that the IRMS value represented the "true" value against which we could compare the stable isotope results from the IRIS methods. Samples showing significant deviations from the IRMS value (>2σ) were considered to be contaminated and representative of spectral interference in the IRIS measurement. Over the two studies, 83% of plant species were considered contaminated on OA-ICOS and 58% on WS-CRDS. Post-analysis, spectra were analyzed using the manufacturer's spectral analysis software, in order to see if the software correctly identified contaminated samples. In our tests the software performed well, identifying all the samples with major errors. However, some false negatives indicate that user evaluation and testing of the software are necessary. Repeat sampling of plants showed considerable variation in the discrepancies between IRIS and IRMS. As such, we recommend that spectral analysis of IRIS data must be incorporated into standard post-processing routines. Furthermore, we suggest that the results from spectral analysis be

  2. Isotope ratio determinations by inductively coupled plasma/mass spectrometry for zinc bioavailability studies

    International Nuclear Information System (INIS)

    A method is described for the measurement of 67Zn/68Zn and 70Zn/68Zn ratios by inductively coupled plasma/mass spectrometry with ultrasonic nebulization. The method provides sufficient accuracy and precision for zinc bioavailability studies that use samples of human feces or blood plasma. Extraction of zinc from ashed samples yields aqueous solutions sufficiently devoid of matrix ions that could affect count rates and isotope ratios. Effects of sodium matrix, zinc concentration, and instrumental parameters on the precision of isotope ratio determinations are documented. Additions of spikes enriched in 67Zn and 70Zn to natural-abundance fecal samples verify that ratios can be determined on solutions 30 μM in zinc (70Zn and to 84 atom% excess of 67Zn. (Auth.)

  3. Stable carbon isotope reconstruction of ungulate diet changes through the seasonal cycle

    OpenAIRE

    Codron, D.; Lee-Thorp, J A; M. Sponheimer; J. Codron

    2007-01-01

    We analysed stable carbon isotope ratios (13C) in faeces of 11 African ungulate species from three South African savanna environments to determine whether this approach is sufficiently sensitive to record short-term seasonal diet changes in browsers (BR), mixed-feeders (IM), and grazers (GR). At monthly intervals, faecal 13C revealed variations in proportions of C3 (browse) to C4 (grass) biomass consumed that were not detected by broader dry versus wet season comparisons, including subtle die...

  4. Measurement of sulfur isotope ratios in micrometer-sized samples by NanoSIMS

    International Nuclear Information System (INIS)

    Sulfur isotope ratios of atmospheric aerosol particles can provide detailed information with regard to the origin and the transport of sulfur in the environment. The new Cameca NanoSIMS 50 ion microprobe technique permits analysis of individual aerosol particles with volumes down to 0.5 μm3 and a precision for δ34S of 3-10 per mille (2σ). This technique will set new standards in the analysis of isotope ratios in atmospheric aerosol. For the first time it is possible to directly compare chemical and isotopic composition of individual aerosol particles, identify internal and external mixtures and investigate reactions of anthropogenic gases with natural aerosol such as sea salt and mineral dust

  5. Locally Grown, Natural Ingredients? The Isotope Ratio Can Reveal a Lot!

    Science.gov (United States)

    Rossier, Joël S; Maury, Valérie; Pfammatter, Elmar

    2016-01-01

    This communication gives an overview of selected isotope analyses applied to food authenticity assessment. Different isotope ratio detection technologies such as isotope ratio mass spectrometry (IRMS) and cavity ring down spectroscopy (CRDS) are briefly described. It will be explained how δ(18)O of water contained in fruits and vegetables can be used to assess their country of production. It will be explained why asparagus grown in Valais, in the centre of the Alps carries much less heavy water than asparagus grown closer to the sea coast. On the other hand, the use of δ(13)C can reveal whether a product is natural or adulterated. Applications including honey or sparkling wine adulteration detection will be briefly presented. PMID:27198812

  6. Studies on treatment methods of the safeguards swipe samples for uranium isotope ratio measurement

    International Nuclear Information System (INIS)

    In the environmental sampling and analyses for safeguards, an accurate isotope ratio of uranium at trace levels is required for detection of undeclared nuclear activities. Currently, swipe (smear) samples are being taken by IAEA from nuclear facilities. The amount of uranium collected on the cotton swipe is expected to be in the wide range including the order of nano-gram or less. In order to measure the isotope ratios by ICP-MS, we have studied sample preparation procedures for the trace amount of uranium. Elements causing spectroscopic and non-spectroscopic interferences in ICP-MS measurement were sufficiently removed by anion-exchange of hydrochloric acid media. The uranium contamination introduced throughout the process the sample preparation was below 10 pg uranium per sample. The applicability of the treatment process for uranium isotope measurement up to 100 pico-grams was proposed. (author)

  7. Isotopic fractionation between organic carbon and carbonate carbon in Precambrian banded ironstone series from Brazil

    International Nuclear Information System (INIS)

    37 delta13Csub(org) and 9 delta13Csub(carb) values furnished by argillaceous and carbonate sediments from the Rio das Velhas and Minas Series (Minas Gerais, Brazil) have yielded means of -24.3 +- 3.9 promille [PDB] and -0.9 +- 1.4 promille [PDB], respectively. These results, obtained from a major sedimentary banded ironstone province with an age between 2 and 3 x 109 yr, support previous assumptions that isotopic fractionation between inorganic and organic carbon in Precambrian sediments is about the same as in Phanerozoic rocks. This is consistent with a theoretically expected constancy of the kinetic fractionation factor governing biological carbon fixation and, likewise, with a photosynthetic pedigree of the reduced carbon fraction of Precambrian rocks. (orig.)

  8. Clumped Isotopes Applied to Carbonate Diagenesis and High Temperature Systems

    Science.gov (United States)

    John, C. M.; Jourdan, A.; Kluge, T.; Dale, A.; Davis, S.; Vandeginste, V.

    2012-12-01

    The field of clumped isotopes is concerned with the state of ordering of natural substances and aims at constraining the abundance of 18O-13C bonds (i.e. a 'clump') within the lattice of carbonate minerals. Measuring the difference between the abundance of 18O-13C bonds in a sample relative to a stochastic distribution of isotopologues offers a single-phase paleothermometer applicable to all carbonate phases. Most of the applications of clumped isotopes to date have been in the field of paleoclimate, but applications to diagenetic systems are becoming more common. The independence of clumped isotopes from the isotopic composition of the diagenetic fluid reduces ambiguities when interpreting paragenesis, fluid flow history, and thermal history of basins. This presentation will synthesize the results of several projects within our group that collectively aim at understanding and applying clumped isotopes to diagenetic systems. One example of project including diagenesis and clumped isotope is a study of low-temperature diagenetic calcite in a salt dome in Oman (Jebel Madar). Jebel Madar is an ideal case study as large fracture-related crystals can be sampled for both clumped isotopes and fluid inclusions. Results show a good match between single-phase fluid inclusions suggesting temperature of precipitations below 90-50°C, and clumped isotope data measured on the same crystals. The low-temperature study reveals the history of gradual cooling and progressive mixing between two sources of diagenetic fluids in the fracture of Jebel Madar, and highlights the potential of clumped isotope for diagenetic studies. However, applications at high-temperatures are currently more challenging because of the lack of empirical calibrations above 50°C. A second project is thus focused on a series of high-temperature lab precipitation experiments for calibrations at high temperature, while a third project explores applicability of clumped isotopes to cemented siliciclastic units

  9. Oxygen and carbon isotopic growth record in a reef coral from the florida keys and a deep-sea coral from blake plateau

    Science.gov (United States)

    Emiliani, C.; Harold, Hudson J.; Shinn, E.A.; George, R.Y.

    1978-01-01

    Carbon and oxygen isotope analysis through a 30-year (1944 to 1974) growth of Montastrea annularis from Hen and Chickens Reef (Florida Keys) shows a strong yearly variation in the abundances of both carbon-13 and oxygen-18 and a broad inverse relationship between the two isotopes. Normal annual dense bands are formed during the summer and are characterized by heavy carbon and light oxygen. "Stress bands" are formed during particularly severe winters and are characterized by heavy carbon and heavy oxygen. The isotopic effect of Zooxanthellae metabolism dominates the temperature effect on the oxygen-18/oxygen-16 ratio. The isotopic results on the deep-sea solitary coral Bathypsammia tintinnabulum, where Zooxanthellae are nonexistent, indicates that the abundance of the heavy isotopes carbon-13 and oxygen-18 is inversely related to the growth rate, with both carbon and oxygen approaching equilibrium values with increasing skeletal age.

  10. Degradation of Perchloroethene by zero-valent iron evaluated by carbon isotope fractionation

    Science.gov (United States)

    Leitner, Simon; Watzinger, Andrea; Reichenauer, Thomas G.

    2014-05-01

    Perchloroethene (PCE) is a widely spread groundwater contaminant in formally used industrial sites. Zero valent iron (ZVI) is used for in situ chemical reduction (ISCR) of PCE contaminants in the groundwater. A key factor in the application of in situ remediation technologies is a proper monitoring of contaminant reduction. The measurement of the stable isotope ratio is a promising method that is already used for quantifying microbial degradation of chlorinated contaminants. The carbon isotope ratio of PCE, measured by - isotope ratio mass spectrometry coupled to a gas chromatograph via a combustion interface (GC-C-IRMS), increases during degradation of PCE and can be directly related to the degree of degradation. It can be used to directly quantify chemical degradation and thus serves as a useful monitoring tool for groundwater remediation. An experiment to determine the carbon isotopic fractionation factor was performed as a lab experiment using Nanofer Star (NANOIRON). Two different PCE concentrations (c1: 220mgL-1, c2: 110mgL-1) mixed with 0.5 g of ZVI were sealed under deoxygenated conditions in 250 ml glas bottles locked with mininert caps. The bottles were incubated on a shaker for 865 h. Samples were taken weekly to measure the change in the carbon isotopic ratio of PCE as well as its concentration. Results showed a strong increase in the carbon isotope ratio (δ-value) of PCE (start: -27 o end: -4 ), which indicates a significant dechlorination process of PCE. Beside PCE also one degradation product (Trichloroethylene - TCE) was measured. TCE was further dechlorinated as indicated by the δ-value change of TCE from -26 o to -4 oȦn unexpected intermediate value of -45 o for TCE was observed in the experiment. This fluctuation could be induced by the time depending concentration due to degradation and conversation processes. Furthermore, it seems that the progress of the δ-value is affected by the starting concentration of PCE (δ-value of c1 < c2) as

  11. An experimental set-up for carbon isotopic analysis of atmospheric CO2 and an example of ecosystem response during solar eclipse 2010

    OpenAIRE

    Guha, Tania; Ghosh, Prosenjit

    2013-01-01

    We present here, an experimental set-up developed for the first time in India for the determination of mixing ratio and carbon isotopic ratio of air-CO2. The set-up includes traps for collection and extraction of CO2 from air samples using cryogenic procedures, followed by the measurement of CO2 mixing ratio using an MKS Baratron gauge and analysis of isotopic ratios using the dual inlet peripheral of a high sensitivity isotope ratio mass spectrometer (IRMS) MAT 253. The internal reproducibil...

  12. Stable carbon isotope discrimination in the smut fungus Ustilago violacea

    International Nuclear Information System (INIS)

    Haploid strains 15.10, I.C429, and I.C2y and diploid strain JK2 of Ustilago Piolacea were grown on one or more of the following carbon sources: glucose, sucrose, maltose, inulin, starch, inositol, glycerol, casein, and yeast extract. The media, both before and after fungal growth, and the fungal cells were analyzed for 13C/12C content (δ13 values) using an isotope ratio mass spectrometer after combustion to CO2. In all cases, the used and unused media had identical δ13C values. Strain 15.10 had significantly less 13C than the media when grown on glucose, sucrose, maltose, and inositol; significantly more 13C when grown on inulin, starch, and glycerol; and no significant difference in δ13C values when grown on casein and yeast extract media. Other haploid strains responded similarly to 15.10. Diploid strain JK2 was also depleted in 13C when grown on glucose and enriched in 13C when grown on glycerol; however, JK2 was slightly depleted in 13C when grown on casein, whereas all the tested haploid strains were enriched in 13C

  13. Carbon-13 kinetic isotope effects in CO oxidation by Ag

    International Nuclear Information System (INIS)

    In the catalytic oxidation of carbon monoxide over silver wool the 13C kinetic isotope effects in the 343--453 K temperature range were experimentally determined and the following temperature dependence was found: 100 ln(k12/k13) = (3.398--630/T) ± 0.083. A reaction CO/O2gas mixture of 1:2 ratio was used in a static system with initial pressures ranging from 20 to 40 kPa. Under these conditions the reaction is of order 1 with respect to CO and order 0 with respect to O2 and CO2 pressure. The apparent activation energy is 59.3 ± 1.7 kJ/mol. In the authors theoretical interpretation of the experimental data various geometries of (CO2)* and (CO3)* transition states were applied, and only a (CO2)* with an interbond angle of 110degree and CO stretching force constants of 1,700 and 1,000--1,400 N/m, respectively, with an asymmetric reaction coordinate was found to be acceptable

  14. Long- Term Stability Study of Isotope Ratio Measurements Uranium and Thorium by Quadrupole Icp Mass Spectrometry

    International Nuclear Information System (INIS)

    Precise isotope ratio measurements of long-lived actinides at trace concentration levels are requite for the characterization of environmental samples (e.g. evidence and extent of 236U contaminate from radioactive waste; geological samples for dating, using the U-Pb method), and radioactive waste material

  15. Laser-mass spectrometric studies on measurement of isotopic ratios Sm and Nd

    International Nuclear Information System (INIS)

    Measurements of isotopic ratio is important in many areas of research such as nuclear technology, geochemistry etc. However, depending on the nature of application of such data, the required accuracy and precision will also vary. For instance, in geochemistry, with subnanogram foraminifera samples, one needs to measure the ratio to within a very small variation (± 50‰) compared to natural isotopic composition. Whereas, in the boron enrichment plant (20-90 atom %), the accuracy needed is about ± 1 atom %. In the former case, one needs to make measurements using an expensive instruments such as a magnetic sector mass spectrometer coupled with a suitable ionization method. For the latter application, one can use less expensive instruments such as, quadrupole mass filer (QMF) or time-of-flight mass spectrometer (TOF-MS) etc. In the present work the effect of pulse width of Nd-YAG laser on the measurement of isotopic ratio of Sm and Nd is studied using an in-house developed Laser Ionization Mass Spectrometer (LIMS) facility. The picosecond Cps) laser seems to provide better data compared to nanosecond (ns) laser. This LIMS method is a relatively simple method to measure the isotope ratios to within ± 1%. (author)

  16. Carbon dioxide gasification of carbon black: isotope study of carbonate catalysis

    International Nuclear Information System (INIS)

    Temperature-programmed reaction was used with labeled isotopes (13C and 18O) to study interactions between carbon black and potassium carbonate in pure He and 10% CO2/90% He atmospheres. Catalytic gasification precursor complexes were observed. Carbon and oxygen-bearing carbon surface groups interacted with the carbonate above 500 K to form surface complexes. Between 500 and 950 K, and in the presence of gaseous CO2, the complexes participated in C and O exchange with the gas phase while oxygen atoms within the complexes also exchanged with those on the carbon surface. As the temperature rose, the complexes decomposed, with CO2 the initial product. Decomposition started around 500 K in pure He, and around 950 K in CO2/He. Catalytic gasification began only after decomposition of significant portions of the complexes. Elemental potassium formed, and the active catalyst appears to alternate between being potassium metal and a potassium-oxygen-carbon complex. Potassium carbonate is not part of the catalytic cycle. 20 references, 10 figures

  17. Carbon isotope discrimination in leaf juice of Acacia mangium and its relationship to water-use efficiency

    Institute of Scientific and Technical Information of China (English)

    lvliu ZOU; Guchou SUN; Ping ZHAO; Xian CAI; Xiaoping ZENG; Xiaojing LIU

    2009-01-01

    Using the PMS pressure chamber and isotope mass spectrometer (MAT-252), the leaf juice of Acacia mangium was obtained, and the carbon isotope discrimination (△) representing the most recently fixed carbon in the juice was determined. At the same time, the water-use efficiency of A. mangium was estimated. The results indicated that the carbon isotope ratio in the air of forest canopy (δa), 10m high above ground averaged -7.57 1.41‰ in cloudy days, and - 8.54±0.67 ‰ in sunny days, respectively. The diurnal change of the carbon isotope ratio in the photosynthetic products of the leaf juice (δp) was of saddle type in cloudy days, but dropped down from morning to later afternoon in sunny days. A strong negative correlation betweenδp and leaf-to-air vapor pressure deficit (D) was observed in sunny days, but a slight change inδp, was found in cloudy days. Theδp also decreased with decreasing leaf water potential (ψ), reflecting that water stress could cause the decrease ofδp. The carbon isotope discrimination of the leaf juice was positively correlated with the ratio between intercellular (Pi) and atmospheric (Pa) partial pressure of CO2. For A. mangium, the isotope effect on diffusion of atmospheric CO2 via stomata was denoted by a = 4.6 %>, and that in net C3 diffusion with respect to Pi was indicated by b = 28.2 ‰. The results were in reasonable accord with the theoretically diffusive and biochemical fractionation of carbon isotope. It was defined that carbon isotope discrimination of photosynthetic products in A. mangium leaf juice was in proportion to that from photosynthetic products in dry material. The water-use efficiency estimated by the carbon isotope discrimination in leaf juice, fit well with that measured by gas exchange system (R2 = 0.86, p< 0.0001). The application of leaf juice in measuring the stable carbon isotope discrimination would reduce the effects of fluctuating environmental factors during the synthesis of dry matter, and improve

  18. Terrestrial carbon isotope excursions and biotic change during Palaeogene hyperthermals

    NARCIS (Netherlands)

    Abels, H.A.; Clyde, W.C.; Gingerich, P.D.; Hilgen, F.J.; Fricke, H.C.; Bowen, G.J.; Lourens, L.J.

    2012-01-01

    Pronounced transient global warming events between 60 and 50 million years ago have been linked to rapid injection of isotopically-light carbon to the ocean–atmosphere system1,2. It is, however, unclear whether the largest of the hyperthermals, the Palaeocene–Eocene Thermal Maximum (PETM; ref. 3), h

  19. Tracing contamination sources in soils with Cu and Zn isotopic ratios

    International Nuclear Information System (INIS)

    Copper (Cu) and zinc (Zn) are naturally present and ubiquitous in soils and are important micronutrients. Human activities contribute to the input of these metals to soils in different chemical forms, which can sometimes reach a toxic level for soil organisms and plants. Isotopic signatures could be used to trace sources of anthropogenic Cu and Zn pollution. The aim of this paper is to determine whether it is possible to identify (i) Cu and Zn contamination in soils and their sources, on the basis of their isotopic signatures, and (ii) situations that are a priori favorable or not for tracing Cu and Zn pollution using the isotopic approach. Therefore, we compiled data from the literature on Cu and Zn isotopes in soils, rocks and pollutants and added to this database the results of our own research. As only a few studies have dealt with agricultural contamination, we also studied a soil toposequence from Brittany, France, that experienced spreading of pig slurry for tens of years. In the surface horizons of the natural soils, the δ65Cu values vary from − 0.15 to 0.44‰ and the δ66Zn from − 0.03 to 0.43‰. Furthermore, vertical variations along soil profiles range from − 0.95 to 0.44‰ for δ65Cu and from − 0.53 to 0.64‰ for δ66Zn values. We concluded that pedogenetic processes can produce isotopic fractionation, yet, it is not always discernible and can be overprinted by an exogenous isotopic signature. Furthermore, some contaminants are enriched in heavy Cu or in light Zn compared to the rock or soil, but no generalization can be made. The anthropogenic inputs can be identified based on stable Cu and Zn isotope ratios if the isotope ratios of the sources are different from those of the soil, which needs to be tested for each individual case. - Highlights: • Pedogenetic processes produce some Cu and Zn isotope fractionation. • Pollution with distinct isotopic signatures can be traced using Cu and Zn isotopes. • Tracing of the metal

  20. Tracing contamination sources in soils with Cu and Zn isotopic ratios

    Energy Technology Data Exchange (ETDEWEB)

    Fekiacova, Z.; Cornu, S. [INRA, UR 1119 Géochimie des Sols et des Eaux, F-13100 Aix en Provence (France); Pichat, S. [Laboratoire de Géologie de Lyon (LGL-TPE), Ecole Normale Supérieure de Lyon, CNRS, UMR 5276, 69007 Lyon (France)

    2015-06-01

    Copper (Cu) and zinc (Zn) are naturally present and ubiquitous in soils and are important micronutrients. Human activities contribute to the input of these metals to soils in different chemical forms, which can sometimes reach a toxic level for soil organisms and plants. Isotopic signatures could be used to trace sources of anthropogenic Cu and Zn pollution. The aim of this paper is to determine whether it is possible to identify (i) Cu and Zn contamination in soils and their sources, on the basis of their isotopic signatures, and (ii) situations that are a priori favorable or not for tracing Cu and Zn pollution using the isotopic approach. Therefore, we compiled data from the literature on Cu and Zn isotopes in soils, rocks and pollutants and added to this database the results of our own research. As only a few studies have dealt with agricultural contamination, we also studied a soil toposequence from Brittany, France, that experienced spreading of pig slurry for tens of years. In the surface horizons of the natural soils, the δ{sup 65}Cu values vary from − 0.15 to 0.44‰ and the δ{sup 66}Zn from − 0.03 to 0.43‰. Furthermore, vertical variations along soil profiles range from − 0.95 to 0.44‰ for δ{sup 65}Cu and from − 0.53 to 0.64‰ for δ{sup 66}Zn values. We concluded that pedogenetic processes can produce isotopic fractionation, yet, it is not always discernible and can be overprinted by an exogenous isotopic signature. Furthermore, some contaminants are enriched in heavy Cu or in light Zn compared to the rock or soil, but no generalization can be made. The anthropogenic inputs can be identified based on stable Cu and Zn isotope ratios if the isotope ratios of the sources are different from those of the soil, which needs to be tested for each individual case. - Highlights: • Pedogenetic processes produce some Cu and Zn isotope fractionation. • Pollution with distinct isotopic signatures can be traced using Cu and Zn isotopes. • Tracing

  1. Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

    2007-06-25

    Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated

  2. Use of isotope ratio mass spectrometry to differentiate between endogenous steroids and synthetic homologues in cattle: A review

    Energy Technology Data Exchange (ETDEWEB)

    Janssens, Geert, E-mail: Geert.janssens@favv.be [Federal Agency for the Safety of the Food Chain, Directorate General Laboratories, Kruidtuinlaan 55, 1000 Brussels (Belgium); Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent (Belgium); Courtheyn, Dirk [Federal Agency for the Safety of the Food Chain, Directorate General Laboratories, Kruidtuinlaan 55, 1000 Brussels (Belgium); Mangelinckx, Sven [Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent (Belgium); Prévost, Stéphanie; Bichon, Emmanuelle; Monteau, Fabrice [LUNAM Université, Oniris, Laboratoire d’Etude des Résidus et Contaminants dans les Aliments (LABERCA), F-44307 Nantes (France); De Poorter, Geert [Federal Agency for the Safety of the Food Chain, Directorate General Laboratories, Kruidtuinlaan 55, 1000 Brussels (Belgium); De Kimpe, Norbert [Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent (Belgium); Le Bizec, Bruno [LUNAM Université, Oniris, Laboratoire d’Etude des Résidus et Contaminants dans les Aliments (LABERCA), F-44307 Nantes (France)

    2013-04-15

    Graphical abstract: Scheme: Representation of the observed isotope ratios and the relation to exogenous and endogenous natural steroids. AS stands for “amount of steroid”. Highlights: ► The difference between endogenous and exogenous steroids is thoroughly laid out. ► Factors influencing the carbon ratio and the use of Δ{sup 13}C-values are explained. ► Implementation of GC/C/IRMS to detect steroid abuse in cattle is reviewed. ► Alternative methods and upcoming techniques are discussed. ► The differences and similarities with sports doping control are highlighted. -- Abstract: Although substantial technical advances have been achieved during the past decades to extend and facilitate the analysis of growth promoters in cattle, the detection of abuse of synthetic analogs of naturally occurring hormones has remained a challenging issue. When it became clear that the exogenous origin of steroid hormones could be traced based on the {sup 13}C/{sup 12}C isotope ratio of the substances, GC/C/IRMS has been successfully implemented to this aim since the end of the past century. However, due to the costly character of the instrumental setup, the susceptibility of the equipment to errors and the complex and time consuming sample preparation, this method is up until now only applied by a limited number of laboratories. In this review, the general principles as well as the practical application of GC/C/IRMS to differentiate between endogenous steroids and exogenously synthesized homologous compounds in cattle will be discussed in detail, and will be placed next to other existing and to be developed methods based on isotope ratio mass spectrometry. Finally, the link will be made with the field of sports doping, where GC/C/IRMS has been established within the World Anti-Doping Agency (WADA) approved methods as the official technique to differentiate between exogenous and endogenous steroids over the past few years.

  3. Use of isotope ratio mass spectrometry to differentiate between endogenous steroids and synthetic homologues in cattle: A review

    International Nuclear Information System (INIS)

    Graphical abstract: Scheme: Representation of the observed isotope ratios and the relation to exogenous and endogenous natural steroids. AS stands for “amount of steroid”. Highlights: ► The difference between endogenous and exogenous steroids is thoroughly laid out. ► Factors influencing the carbon ratio and the use of Δ13C-values are explained. ► Implementation of GC/C/IRMS to detect steroid abuse in cattle is reviewed. ► Alternative methods and upcoming techniques are discussed. ► The differences and similarities with sports doping control are highlighted. -- Abstract: Although substantial technical advances have been achieved during the past decades to ext