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Sample records for carbon stable isotope

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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

  6. Stable carbon isotope ratios of ambient aromatic volatile organic compounds

    Science.gov (United States)

    Kornilova, Anna; Huang, Lin; Saccon, Marina; Rudolph, Jochen

    2016-09-01

    Measurements of mixing ratios and stable carbon isotope ratios of aromatic volatile organic compounds (VOC) in the atmosphere were made in Toronto (Canada) in 2009 and 2010. Consistent with the kinetic isotope effect for reactions of aromatic VOC with the OH radical the observed stable carbon isotope ratios are on average significantly heavier than the isotope ratios of their emissions. The change of carbon isotope ratio between emission and observation is used to determine the extent of photochemical processing (photochemical age, ∫ [OH]dt) of the different VOC. It is found that ∫ [OH]dt of different VOC depends strongly on the VOC reactivity. This demonstrates that for this set of observations the assumption of a uniform ∫ [OH]dt for VOC with different reactivity is not justified and that the observed values for ∫ [OH]dt are the result of mixing of VOC from air masses with different values for ∫ [OH]dt. Based on comparison between carbon isotope ratios and VOC concentration ratios it is also found that the varying influence of sources with different VOC emission ratios has a larger impact on VOC concentration ratios than photochemical processing. It is concluded that for this data set the use of VOC concentration ratios to determine ∫ [OH]dt would result in values for ∫ [OH]dt inconsistent with carbon isotope ratios and that the concept of a uniform ∫ [OH]dt for an air mass has to be replaced by the concept of individual values of an average ∫ [OH]dt for VOC with different reactivity.

  7. STABLE CARBON ISOTOPE ANALYSIS OF SUBFOSSIL WOOD FROM AUSTRIAN ALPS

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    KŁUSEK, MARZENA; PAWEŁCZYK, SŁAWOMIRA

    2015-01-01

    The presented studies were carried out in order to check the usefulness of subfossil wood for stable isotope analysis. The aim of research was also to define the optimal method of subfossil samples preparation. Subfossil samples used during the presented studies are a part of the multi-century dendrochronological scale. This chronology originates in an area situated around a small mountain lake — Schwarzersee, in Austria. The obtained results of stable carbon isotope measurements confirmed that the method of α-cellulose extraction by the application of acidic sodium chlorite and sodium hydroxide solutions removes resins and other mobile compounds from wood. Therefore, in the case of the analysed samples, the additional chemical process of extractives removing was found to be unnecessary. Studied wood samples contained an adequate proportion of α-cellulose similar to the values characteristic for the contemporary trees. This proved an adequate wood preservation which is essential for the conduction of isotopic research. PMID:26346297

  8. Modeling stable isotope and organic carbon in hillslope stormflow

    Science.gov (United States)

    Dusek, Jaromir; Vogel, Tomas; Dohnal, Michal; Marx, Anne; Jankovec, Jakub; Sanda, Martin; Votrubova, Jana; Barth, Johannes A. C.; Cislerova, Milena

    2016-04-01

    Reliable prediction of water movement and fluxes of dissolved substances (such as stable isotopes and organic carbon) at both the hillslope and the catchment scales remains a challenge due to complex boundary conditions and soil spatial heterogeneity. In addition, microbially mediated transformations of dissolved organic carbon (DOC) are known to affect balance of DOC in soils, hence the transformations need to be included in a conceptual model of a DOC transport. So far, only few studies utilized stable isotope information in modeling and even fewer linked dissolved carbon fluxes to mixing and/or transport models. In this study, stormflow dynamics of oxygen-18 isotope and dissolved organic carbon was analyzed using a physically based modeling approach. One-dimensional dual-continuum vertical flow and transport model, based on Richards and advection-dispersion equations, was used to simulate the subsurface transport processes in a forest soil during several observed rainfall-runoff episodes. The transport of heat in the soil profile was described by conduction-advection equation. Water flow and transport of solutes and heat were assumed to take place in two mutually communicating porous domains, the soil matrix and the network of preferential pathways. The rate of microbial transformations of DOC was assumed to depend on soil water content and soil temperature. Oxygen-18 and dissolved organic carbon concentrations were observed in soil pore water, hillslope stormflow (collected in the experimental hillslope trench), and stream discharge (at the catchment outlet). The modeling was used to analyze the transformation of input solute signals into output hillslope signals observed in the trench stormflow. Signatures of oxygen-18 isotope in hillslope stormflow as well as isotope concentration in soil pore water were predicted reasonably well. Due to complex nature of microbial transformations, prediction of DOC rate and transport was associated with a high uncertainty.

  9. Investigating the Formation of Pedogenic Carbonate Using Stable Isotopes

    Science.gov (United States)

    Breecker, D. O.; Sharp, Z. D.; McFadden, L.

    2006-12-01

    The stable isotope composition of pedogenic carbonate has been used as a paleoenvironmental proxy because it is thought to form in isotopic equilibrium with soil CO2 and soil water, which are influenced by vegetation type and atmospheric circulation patterns, respectively. However, the isotopic composition of soil CO2 and soil water change seasonally and it is not known what portion of this variability is recorded by the isotopic composition of pedogenic carbonate. It is generally believed that carbonate precipitation in soils is driven by evaporative concentration of Ca ions and/or decreasing soil pCO2. We seek to improve the proxy by determining the seasonality of pedogenic carbonate formation, in particular whether pedogenic carbonate forms during the wet season after individual rainstorms or during seasonal drying following the wet season. This was done by comparing the variations in carbon and oxygen isotope composition of soil CO2 with the isotopic composition of proximally located, newly-formed carbonates. Soil CO2 and incipient pedogenic carbonate coatings were collected in a very young (soil developing in an inset terrace on the piedmont of the Sandia Mountains, central New Mexico. We also measure soil temperatures at the same site. In May 2006, at the end of the driest 6-month period on record in central New Mexico, soil CO2 profiles displayed a 2‰ decrease in δ13C values with depth from 9 to 100 cm. In August 2006, the shapes of the profiles were similar, but the δ13C values were 3-4‰ lower at each depth than in May. These results can be explained by an increase in respiration rate during the latter half of the summer (the wettest on record) when monsoon rainfall maintained high moisture contents in soils across New Mexico. Calculated δ13C values of calcite in equilibrium with May (but not August) soil CO2 agree with measured carbonate δ13C values below 20 cm depth. Very shallow carbonate has anomalously high δ13C values. Measurements of the

  10. 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

  11. Carbon Stable Isotopes as Indicators of Coastal Eutrophication

    Science.gov (United States)

    Coastal ecologists and managers have frequently used nitrogen stable isotopes (δ15N) to trace and monitor anthropogenic nitrogen (N) in coastal ecosystems. However, the interpretation of δ15N data can often be challenging, if not confounding, as the isotope values fractionate su...

  12. Tracing organic matter sources of estuarine tidal flat nematodes with stable carbon isotopes

    NARCIS (Netherlands)

    Moens, T.; Luyten, C.; Middelburg, J.J.; Herman, P.M.J.; Vincx, M.

    2002-01-01

    The present study explores the use of stable carbon isotopes to trace organic matter sources of intertidal nematodes in the Schelde estuary (SW Netherlands). Stable carbon isotope signatures of nematodes from a saltmarsh and 4 tidal flat stations were determined in spring and winter situations, and

  13. Behaviour of Structural Carbonate Stable Carbon and Oxygen Isotope Compositions in Bioapatite During Burning of Bone

    Science.gov (United States)

    Munro, L. E.; Longstaffe, F. J.; White, C. D.

    2003-12-01

    Bioapatite, the principal inorganic phase comprising bone, commonly contains a small fraction of carbonate, which has been substituted into the phosphate structure during bone formation. The isotopic compositions of both the phosphate oxygen and the structural carbonate oxygen are now commonly used in palaeoclimatological and bioarchaeological investigations. The potential for post-mortem alteration of these isotopic compositions, therefore, is of interest, with the behaviour of structural carbonate being of most concern. In bioarchaeological studies, alteration of bone isotopic compositions has the potential to occur not only during low-temperature processes associated with burial but also during food preparation involving heating (burning, boiling). Here, we examine the stable isotopic behaviour of structural carbonate oxygen and carbon, and coexisting phosphate oxygen during the burning of bone. Freshly deceased (6determined using powder X-ray diffraction (pXRD), and Fourier transform infra-red spectroscopy (FTIR). Combined differential thermal and thermogravimetric analyses (DTA/TG) were used to evaluate weight loss and associated reactions during heating. Stable carbon isotope compositions of the bioapatite remain relatively constant (+/-1‰ ) during heating to 650° C. A 4‰ increase in stable carbon isotopic composition then occurs between 650-750° C, accompanied by an increase in CI, followed by a 10‰ decline at temperatures above 800° C, as carbonate carbon is lost. Carbonate and phosphate oxygen isotopic compositions are correlated over the entire heating range, with carbonate being enriched relative to phosphate by about 8-10‰ below 500° C, 5-6‰ between 500-700° C, and 8-10‰ above 700° C. CI and oxygen isotopic compositions of carbonate and phosphate are not well correlated. Only modest CI changes are recorded from 25-675° C, compared with much larger changes in oxygen isotopic composition, especially above 300° C. On average, original

  14. 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

  15. Stable Carbon Isotope Record in a Palau Sclerosponge

    Science.gov (United States)

    Grottoli, A. G.

    2002-12-01

    The ratio of stable carbon isotopes (δ13C) deposited in the calcium carbonate skeleton of marine sclerosponges appears to record the carbon isotopic composition of seawater mixed-layer dissolved inorganic carbon (δ13CDIC). Thus the δ13C signature chronicled in sclerosponge skeletons offers a promising multi-century proxy record of seawater mixed-layer δ13CDIC throughout the tropics. Here, a high-resolution (0.1 mm) δ13C record for a 7.7 cm Acanthocheatetes wellsi sclerosponge from Palau (7N, 134W) is presented. At a published growth rate of 0.45 mm per year, this record spans ~s170 years beginning in July 2001 and going back to 1831. The δ13C values for a definitive 10-year A. wellsi record spanning 1989-1998 were similar to δ13C values here for the first 4.7 mm of the record providing supporting evidence for the growth rate. The sclerosponge δ13C shows a distinct Seuss Effect. At the time this abstract was submitted, the analysis of the first 16 mm of the sclerosponge revealed a significant decrease in δ13C with time [δ13C = 0.02 (distance) + 2.64, r2 = 0.73, p < 0.0001, where time is marked by distance in millimeters from the growing edge] corresponding to a decrease in δ13C of 0.076‰ per decade. For comparison, published low-frequency measurements in Australian, New Caledonian and Jamaican sclerosponges have yielded decreases in δ13C of ~s0.05 to 0.08 ‰ per decade over the past 40 years. Preliminary interpretation of the data indicates that the amount of atmospheric CO2 contributing to the seawater δ13CDIC at Palau is intermediate to Australia and Jamaica. In addition, visual examination of the δ13C record reveals regular fluctuation in δ13C that may correspond to annual variability in δ13CDIC. This research presents the first century or longer sclerosponge δ13C record from the northwester equatorial Pacific.

  16. Application of stable carbon isotopes in long term mesocosm studies for carbon cycle investigation

    Science.gov (United States)

    Esposito, Mario

    2016-04-01

    Carbon dioxide (CO2) is an effective greenhouse gas. The Oceans absorb ca. 30% of the anthropogenic CO2 emissions and thereby partly attenuate deleterious climate effects. A consequence of the oceanic CO2 uptake is a decreased seawater pH and planktonic community shifts. The quantification of the anthropogenic perturbation was investigated through stable carbon isotope analysis in three "long term" mesocosm experiments (Sweden 2013, Gran Canaria 2014, Norway 2015) which reproduced near natural ecosystem conditions under both controlled and modified future CO2 level (up to 2000 ppm) scenarios. Parallel measurements of the stable isotope composition of dissolved inorganic carbon (δ13CDIC) dissolved organic carbon (δ13CDOC) and particulate carbon (δ13CTPC) both from the mesocosms water column and sediment traps showed similar trends in all the three experiments. A CO2 response was noticeable in the isotopic dataset, but increased CO2 levels had only a subtle effect on the concentrations of the dissolved and particulate organic carbon pool. Distinctive δ13C signatures of the particulate carbon pool both in the water column and the sediments were detectable for the different CO2 treatments and they were strongly correlated with the δ13CDIC signatures but not with the δ13CDOC pool. The validity of the isotopic data was verified by cross-analyses of multiple substances of known isotopic signatures on a GasBench, Elemental Analyser (EA) and on an in-house TOC-IRMS setup for the analysis of δ13CDIC, δ13CTPC and δ13CDOC, respectively. Results from these mesocosm experiments proved the stable carbon isotope approach to be an effective tool for quantifying the uptake and carbon transfer among the various compartments of the marine carbon system.

  17. 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

  18. Stable Carbon Isotope Fractionation by Methylotrophic Methanogenic Archaea

    OpenAIRE

    Penger, Jörn; Conrad, Ralf; Blaser, Martin

    2012-01-01

    In natural environments methane is usually produced by aceticlastic and hydrogenotrophic methanogenic archaea. However, some methanogens can use C1 compounds such as methanol as the substrate. To determine the contributions of individual substrates to methane production, the stable-isotope values of the substrates and the released methane are often used. Additional information can be obtained by using selective inhibitors (e.g., methyl fluoride, a selective inhibitor of acetoclastic methanoge...

  19. 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

  20. 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.

  1. Low stable carbon isotope fractionation by coccolithophore RubisCO

    Science.gov (United States)

    Boller, Amanda J.; Thomas, Phaedra J.; Cavanaugh, Colleen M.; Scott, Kathleen M.

    2011-11-01

    The 13C/ 12C ratio of carbon compounds is used to identify sources and sinks in the global carbon cycle. However, the relatively enriched 13C content observed for marine organic carbon remains enigmatic. The majority of oceanic carbon is fixed by algae and cyanobacteria via the Calvin-Benson-Bassham cycle, yet isotopic discrimination by the CO 2 fixation enzyme, RubisCO (ribulose 1,5-bisphosphate carboxylase/oxygenase), has only been measured for a single marine cyanobacterium. Different forms of RubisCO occur in different phytoplankton species (overall amino acid identity varying by as much as ˜75%) and thus may vary in the degree to which they fractionate carbon. Here we measured isotope discrimination by RubisCO from the coccolithophore Emiliania huxleyi, a cosmopolitan species used as a marine algal model .E. huxleyi RubisCO discriminated substantially less ( ɛ = 11.1‰) against 13CO 2 than other RubisCO enzymes (18-29‰), despite having Michaelis-Menten kinetic parameters ( K = 72 μM; Vmax = 0.66 μmol min -1 mg -1 protein) similar to those measured for RubisCO enzymes from different organisms. If widespread, decreased isotope discrimination of 13C by phytoplankton RubisCO may be a major factor influencing the enriched 13C content of marine organic carbon. This finding emphasizes the necessity of (a) determining ɛ values for RubisCOs of other marine phytoplankton and (b) re-evaluation of δ13C values from physiological, environmental, and geological studies.

  2. Stable Isotope Studies of Crop Carbon and Water Relations: A Review

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cong-zhi; ZHANG Jia-bao; ZHAO Bing-zi; ZHANG Hui; HUANG Ping

    2009-01-01

    Crop carbon and water relations research is important in the studies of water saving agriculture,breeding program,and energy and material cycles in soil plant atmosphere continuum (SPAC).The purpose of this paper is to review the current state of knowledge on stable isotopes of carbon,oxygen,and hydrogen in the research of crop carbon and water relations,such as carbon isotope discrimination (△13C) during carbon fixation process by photosynthesis,application of △13C in crop water use efficiency (WUE) and breeding programs,oxygen isotope enrichment during leaf water transpiration,CO2 fixation by photosynthesis and release by respiration,application of hydrogen isotope composition (δD) and oxygen isotope composition (δ18O) for determination of water source used by a crop,stable isotope coupling Keeling plot for investigating the carbon and water flux in ecosystem,energy and material cycle in SPAC and correlative integrative models on stable isotope.These aspects contain most of the stable isotope researches on crop carbon and water relations which have been widely explored internationally while less referred in China.Based on the reviewed literatures,some needs for future research are suggested.

  3. Constraining the global bromomethane budget from carbon stable isotopes

    Science.gov (United States)

    Bahlmann, Enno; Wittmer, Julian; Greule, Markus; Zetzsch, Cornelius; Seifert, Richard; Keppler, Frank

    2016-04-01

    Despite intense research in the last two decades, the global bromomethane (CH3Br) budget remains unbalanced with the known sinks exceeding the known sources by about 25%. The reaction with OH is the largest sink for CH3Br. We have determined the kinetic isotope effects for the reactions of CH3Br with the OH and Cl radical in order to better constrain the global CH3Br budget from an isotopic perspective. The isotope fractionation experiments were performed at 20±1°C in a 3500 L Teflon smog-chamber with initial CH3Br mixing ratios of about 2 and 10 ppm and perflourohexane (25 ppb) as internal standard. Atomic chlorine (Cl) was generated via photolysis of molecular chlorine (Cl2) using a solar simulator with an actinic flux comparable to that of the sun in mid-summer in Germany. OH radicals were generated via the photolysis of ozone (O3) at 253.7 nm in the presence of water vapor (RH = 70%).The mixing ratios of CH3Br, and perflourohexane were monitored by GC-MS with a time resolution of 15 minutes throughout the experiments. From each experiment 10 to 15 sub samples were taken in regular time intervals for subsequent carbon isotope ratio determinations by GC-IRMS performed at two independent laboratories in parallel. We found a kinetic isotope effect (KIE) of 17.6±3.3‰ for the reaction of CH3Br with OH and a KIE of 9.8±1.4 ‰ for the reaction with Cl*. We used these fractionation factors along with new data on the isotopic composition of CH3Br in the troposphere (-34±7‰) and the surface ocean (-26±7‰) along with reported source signatures, to constrain the unknown source from an isotopic perspective. The largest uncertainty in estimating the isotopic composition of the unknown source arises from the soil sink. Microbial degradation in soils is the second largest sink and assigned with a large fractionation factors of about 50‰. However, field experiments revealed substantially smaller apparent fractionation factors ranging from 11 to 22‰. In addition

  4. [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

  5. Photosynthetic fractionation of the stable isotopes of oxygen and carbon

    Energy Technology Data Exchange (ETDEWEB)

    Guy, R.D. (Carnegie Institution of Washington, Stanford, CA (United States)); Fogel, M.L.; Berry, J.A. (Carnegie Inst. of Washington, Washington, DC (United States))

    1993-01-01

    Isotope discrimination during photosynthetic exchange of O[sub 2] and CO[sub 2] was measured using enzyme, thylakoid, and whole cell preparations. Evolved oxygen from isolated spinach thylakoids was isotopically identical (within analytical error) to its source water. Similar results were obtained with Anacystis nidulans Richter and Phaeodactylum tricornutum Bohlin cultures purged with helium. For consumptive reactions, discrimination ([triangle], where 1 + [triangle]/1000 equals the isotope effect, k[sup 16]/k[sup 18] or k[sup 12]/k[sup 13]) was determined by analysis of residual substrate (O[sub 2] or CO[sub 2]). The [triangle] for the Mehler reaction, mediated by ferredoxin or methylviologen, was 15.3[per thousand]. Oxygen isotope discrimination during oxygenation of ribulose-1,5-bisphosphate (RuBP) catalyzed by RuBP carboxylase/oxygenase (Rubisco) was 21.3[per thousand] and independent of enzyme source, unlike carbon isotope dicrimination: 30.3[per thousand] for spinach enzyme and 19.6 to 23[per thousand] for Rhodospirillum rubrum and A. nidulans enzymes, depending on reaction conditions. The [triangle] for O[sub 2] consumption catalyzed by glycolate oxidase was 22.7[per thousand]. Consistent with this, when Asparagus sprengeri Regel mesopyll cells approached the compensation point within a sealed vessel, the [delta][sup 18]O of dissolved O[sub 2] came to a steady-state value of about 21.5[per thousand] relative to the source water. The results provide improved estimates of discrimination factors in several reactions prominent in the global oxygen cycle and indicate that photorespiration plays a significant part in determining the isotopic composition of atmospheric oxygen. 47 refs., 8 figs., 2 tabs.

  6. Photosynthetic Fractionation of the Stable Isotopes of Oxygen and Carbon.

    Science.gov (United States)

    Guy, R. D.; Fogel, M. L.; Berry, J. A.

    1993-01-01

    Isotope discrimination during photosynthetic exchange of O2 and CO2 was measured using enzyme, thylakoid, and whole cell preparations. Evolved oxygen from isolated spinach thylakoids was isotopically identical (within analytical error) to its source water. Similar results were obtained with Anacystis nidulans Richter and Phaeodactylum tricornutum Bohlin cultures purged with helium. For consumptive reactions, discrimination ([delta], where 1 + [delta]/1000 equals the isotope effect, k16/k18 or k12/k13) was determined by analysis of residual substrate (O2 or CO2). The [delta] for the Mehler reaction, mediated by ferredoxin or methylviologen, was 15.3[per mille (thousand) sign]. Oxygen isotope discrimination during oxygenation of ribulose-1,5-bisphosphate (RuBP) catalyzed by RuBP carboxylase/oxygenase (Rubisco) was 21.3[per mille (thousand) sign] and independent of enzyme source, unlike carbon isotope discrimination: 30.3[per mille (thousand) sign] for spinach enzyme and 19.6 to 23[per mille (thousand) sign] for Rhodospirillum rubrum and A. nidulans enzymes, depending on reaction conditions. The [delta] for O2 consumption catalyzed by glycolate oxidase was 22.7[per mille (thousand) sign]. The expected overall [delta] for photorespiration is about 21.7[per mille (thousand) sign]. Consistent with this, when Asparagus sprengeri Regel mesophyll cells approached the compensation point within a sealed vessel, the [delta]18O of dissolved O2 came to a steady-state value of about 21.5[per mille (thousand) sign] relative to the source water. The results provide improved estimates of discrimination factors in several reactions prominent in the global O cycle and indicate that photorespiration plays a significant part in determining the isotopic composition of atmospheric oxygen. PMID:12231663

  7. Linking mercury, carbon, and nitrogen stable isotopes in Tibetan biota: Implications for using mercury stable isotopes as source tracers.

    Science.gov (United States)

    Xu, Xiaoyu; Zhang, Qianggong; Wang, Wen-Xiong

    2016-05-06

    Tibetan Plateau is located at a mountain region isolated from direct anthropogenic sources. Mercury concentrations and stable isotopes of carbon, nitrogen, and mercury were analyzed in sediment and biota for Nam Co and Yamdrok Lake. Biotic mercury concentrations and high food web magnification factors suggested that Tibetan Plateau is no longer a pristine site. The primary source of methylmercury was microbial production in local sediment despite the lack of direct methylmercury input. Strong ultraviolet intensity led to extensive photochemical reactions and up to 65% of methylmercury in water was photo-demethylated before entering the food webs. Biota displayed very high Δ(199)Hg signatures, with some highest value (8.6%) ever in living organisms. The δ(202)Hg and Δ(199)Hg in sediment and biotic samples increased with trophic positions (δ(15)N) and %methylmercury. Fish total length closely correlated to δ(13)C and Δ(199)Hg values due to dissimilar carbon sources and methylmercury pools in different living waters. This is the first mercury isotope study on high altitude lake ecosystems that demonstrated specific isotope fractionations of mercury under extreme environmental conditions.

  8. Linking mercury, carbon, and nitrogen stable isotopes in Tibetan biota: Implications for using mercury stable isotopes as source tracers

    Science.gov (United States)

    Xu, Xiaoyu; Zhang, Qianggong; Wang, Wen-Xiong

    2016-05-01

    Tibetan Plateau is located at a mountain region isolated from direct anthropogenic sources. Mercury concentrations and stable isotopes of carbon, nitrogen, and mercury were analyzed in sediment and biota for Nam Co and Yamdrok Lake. Biotic mercury concentrations and high food web magnification factors suggested that Tibetan Plateau is no longer a pristine site. The primary source of methylmercury was microbial production in local sediment despite the lack of direct methylmercury input. Strong ultraviolet intensity led to extensive photochemical reactions and up to 65% of methylmercury in water was photo-demethylated before entering the food webs. Biota displayed very high Δ199Hg signatures, with some highest value (8.6%) ever in living organisms. The δ202Hg and Δ199Hg in sediment and biotic samples increased with trophic positions (δ15N) and %methylmercury. Fish total length closely correlated to δ13C and Δ199Hg values due to dissimilar carbon sources and methylmercury pools in different living waters. This is the first mercury isotope study on high altitude lake ecosystems that demonstrated specific isotope fractionations of mercury under extreme environmental conditions.

  9. Seasonal variation in stable carbon and nitrogen isotope values of bats reflect environmental baselines.

    Directory of Open Access Journals (Sweden)

    Ana G Popa-Lisseanu

    Full Text Available The stable carbon and nitrogen isotope composition of animal tissues is commonly used to trace wildlife diets and analyze food chains. Changes in an animal's isotopic values over time are generally assumed to indicate diet shifts or, less frequently, physiological changes. Although plant isotopic values are known to correlate with climatic seasonality, only a few studies restricted to aquatic environments have investigated whether temporal isotopic variation in consumers may also reflect environmental baselines through trophic propagation. We modeled the monthly variation in carbon and nitrogen isotope values in whole blood of four insectivorous bat species occupying different foraging niches in southern Spain. We found a common pattern of isotopic variation independent of feeding habits, with an overall change as large as or larger than one trophic step. Physiological changes related to reproduction or to fat deposition prior to hibernation had no effect on isotopic variation, but juvenile bats had higher δ13C and δ15N values than adults. Aridity was the factor that best explained isotopic variation: bat blood became enriched in both 13C and 15N after hotter and/or drier periods. Our study is the first to show that consumers in terrestrial ecosystems reflect seasonal environmental dynamics in their isotope values. We highlight the danger of misinterpreting stable isotope data when not accounting for seasonal isotopic baselines in food web studies. Understanding how environmental seasonality is integrated in animals' isotope values will be crucial for developing reliable methods to use stable isotopes as dietary tracers.

  10. Seasonal variation in stable carbon and nitrogen isotope values of bats reflect environmental baselines.

    Science.gov (United States)

    Popa-Lisseanu, Ana G; Kramer-Schadt, Stephanie; Quetglas, Juan; Delgado-Huertas, Antonio; Kelm, Detlev H; Ibáñez, Carlos

    2015-01-01

    The stable carbon and nitrogen isotope composition of animal tissues is commonly used to trace wildlife diets and analyze food chains. Changes in an animal's isotopic values over time are generally assumed to indicate diet shifts or, less frequently, physiological changes. Although plant isotopic values are known to correlate with climatic seasonality, only a few studies restricted to aquatic environments have investigated whether temporal isotopic variation in consumers may also reflect environmental baselines through trophic propagation. We modeled the monthly variation in carbon and nitrogen isotope values in whole blood of four insectivorous bat species occupying different foraging niches in southern Spain. We found a common pattern of isotopic variation independent of feeding habits, with an overall change as large as or larger than one trophic step. Physiological changes related to reproduction or to fat deposition prior to hibernation had no effect on isotopic variation, but juvenile bats had higher δ13C and δ15N values than adults. Aridity was the factor that best explained isotopic variation: bat blood became enriched in both 13C and 15N after hotter and/or drier periods. Our study is the first to show that consumers in terrestrial ecosystems reflect seasonal environmental dynamics in their isotope values. We highlight the danger of misinterpreting stable isotope data when not accounting for seasonal isotopic baselines in food web studies. Understanding how environmental seasonality is integrated in animals' isotope values will be crucial for developing reliable methods to use stable isotopes as dietary tracers. PMID:25700080

  11. Trophic ecology of small yellow croaker (Larimichthys polyactis Bleeker): stable carbon and nitrogen isotope evidence

    Institute of Scientific and Technical Information of China (English)

    JI Weiwei; CHEN Xuezhong; JIANG Yazhou; LI Shengfa

    2011-01-01

    The trophic ecology of the small yellow croaker (Larimichthys polyactis) was studied using stable isotope analyses.Samples were collected from July to September 2009 and 34 individuals from eight sites were examined for stable carbon and nitrogen isotopes.Stable carbon isotope ratios (δ13C)ranged from -20.67 to -15.43,while stable nitrogen isotope ratios (δ15N) ranged 9.18-12.23.The relationship between δ13C and δ15N suggested high resource partitioning in the sampling area.Significant differences in stable isotope values among the eight sampling sites may be linked to environmental diversities involving various physical processes (such as ocean current,wind and tide) and different carbon sources.Furthermore,the stable isotope ratios may also explain the ontogenetic variability in diet and feeding,because δ13C and δ15N varied significantly with increasing body size.The findings are consistent with other studies on diet analyses in small yellow croaker.It was also demonstrated that stable isotope analysis could be used to estimate the trophic characters of small yellow croaker in feeding patterns and migrating habits.

  12. Stable Carbon and Oxygen Isotopes of Pedogenic Carbonates in Ustic Vertisols: Implications for Paleoenvironmental Change

    Institute of Scientific and Technical Information of China (English)

    HUANG Cheng-Min; WANG Cheng-Shan; TANG Ya

    2005-01-01

    Pedogenic carbonates, found extensively in arid and semiarid regions, are important in revealing regional climatic and environmental changes as well as the carbon cycle. In addition, stable carbon and oxygen isotopic compositions of pedogenic carbonates have been used to rebuild paleoecology (biomass and vegetation) and to estimate paleotemperature and paleoprecipitation during past geological time. By utilizing the stable carbon and oxygen isotopic compositions (δ13C and δ18O) of secondary nodules in Ustic Vertisols, this study looked into the climatic and environmental changes in the dry valleys of the Yuanmou Basin, Yunnan Province, in southwestern China. The results showed that during the early Holocene, a warm-humid or hot-humid climate existed in the Yuanmou Basin, but since then fluctuations in climate have occurred, with a dry climate prevailing. A highly significant correlation (r = 0.92, n= 9) between δ13C and δ18O values of carbonates illustrated that there had been a continual shifting between cold-humid and warm-dry climates in southwestern China including the Yuanmou Basin since the early Holocene.

  13. 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.

  14. 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...

  15. 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.)

  16. 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

  17. Distribution and fractionation mechanism of stable carbon isotope of coalbed methane

    Institute of Scientific and Technical Information of China (English)

    QIN; Shengfei; TANG; Xiuyi; SONG; Yan; WANG; Hongyan

    2006-01-01

    The stable carbon isotope values of coalbed methane range widely,and also are generally lighter than that of gases in normal coal-formed gas fields with similar coal rank.There exists strong carbon isotope fractionation in coalbed methane and it makes the carbon isotope value lighter.The correlation between the carbon isotope value and Ro in coalbed methane is less obvious.The coaly source rock maturity cannot be judged by coalbed methane carbon isotope value.The carbon isotopes of coalbed methane become lighter in much different degree due to the hydrodynamics.The stronger the hydrodynamics is,the lighter the CBM carbon isotopic value becomes.Many previous investigations indicated that the desorption-diffusion effects make the carbon isotope value of coalbed methane lighter.However,the explanation has encountered many problems.The authors of this article suggest that the flowing groundwater dissolution to free methane in coal seams and the free methane exchange with absorbed one is the carbon isotope fractionation mechanism in coalbed methane.The flowing groundwater in coal can easily take more 13CH4 away from free gas and comparatively leave more 12CH4.This will make 12CH4 density in free gas comparatively higher than that in absorbed gas.The remaining 12CH4 in free gas then exchanges with the adsorbed methane in coal matrix.Some absorbed 13CH4 can be replaced and become free gas.Some free 12CH4 can be absorbed again into coal matrix and become absorbed gas.Part of the newly replaced 13CH4 in free gas will also be taken away by water,leaving preferentially more 12CH4.The remaining 12CH4 in free gas will exchange again with adsorbed methane in the coal matrix.These processes occur all the time.Through accumulative effect,the 12CH4 will be greatly concentrated in coal.Thus,the stable carbon isotope of coalbed methane becomes dramatically lighter.Through simulation experiment on water-dissolved methane,it had been proved that the flowing water could fractionate the

  18. The Stable and Radio- Carbon Isotopic Content of Labile and Refractory Carbon in Atmospheric Particulate Matter

    Science.gov (United States)

    McNichol, A. P.; Rosenheim, B. E.; Gerlach, D. S.; Hayes, J. M.

    2006-12-01

    Studies of the isotopic content of atmospheric particulate matter are hampered by difficulties in chemically defining the pools of carbon and analytically isolating the different pools. We are conducting studies on reference materials and atmospheric aerosol samples to develop a method to measure stable and radio- carbon isotopes on the labile and refractory carbon. We are using a flow-through combustion system that allows us to combust, collect and measure the isotopic content of the gases produced at all stages of heating/oxidizing. We compare our results to those measured using a chemothermal oxidation method (CTO) (Gustafsson et al., 2001). In this method, refractory carbon is defined as the material remaining after pre- combusting a sample at 375°C in the presence of oxygen for 24 hours. The reference materials are diesel soot, apple leaves and a hybrid of the two (DiesApple), all from NIST. These provide carbon with two well-defined fractions -- the soot provides refractory carbon that is radiocarbon dead and the apple leaves provide organic carbon that is radiocarbon modern. Radiocarbon results from DiesApple indicate that the "refractory" carbon defined by the CTO method is actually a mixture of old and modern carbon that contains over 25% modern carbon. This suggests that charred material formed from the apples leaves during the pre-combustion step is contributing to the fraction we identify as refractory carbon. We are studying this by analyzing the individual materials and the mixture using our flow-through system. First results with this system indicate that the refractory fraction trapped from the DiesApple contains much less modern carbon than the CTO method, less than 7%. We will present detailed concentration and isotopic results of the generation of carbon dioxide during programmed combustion of each of the reference materials. We studied the radiocarbon content of both the total carbon (TC) and refractory carbon in the fine particulate matter (PM

  19. Stable carbon isotope analyses in sediments and its implications for reconstructing climatic and environmental changes

    International Nuclear Information System (INIS)

    The relative significance of the 20th-century climatic and environmental changes must be assessed form the long-term global-scale perspective available from a spectrum of proxy histories. In many cases geochemical proxies in sediments are needed to supplement the established use of the stable isotope analyses for paleotemperature and paleo-hydrological modeling so as to understand the past environment conditions and evaluate predictive models of climate. The stable carbon isotope fractionation during photosynthesis and the system CO2 (gas)-CO2-(aqueous)-HCO3- (aqueous) are reviewed; and application of the stable carbon isotope to reconstruction of palaeo-climatic and palaeo-environmental changes, especially CO2 levels during the late Quaternary are discussed

  20. Stable Isotopic Evidence for a Pedogenic Origin of Carbonates in Trench 14 near Yucca Mountain, Nevada.

    Science.gov (United States)

    Quade, J; Cerling, T E

    1990-12-14

    Layered carbonate and silica encrust fault fractures exposed in Trench 14 near Yucca Mountain, site of the proposed high-level nuclear waste repository in southern Nevada. Comparison of the stable carbon and oxygen isotopic compositions of the fracture carbonates with those of modern soil carbonates in the area shows that the fracture carbonates are pedogenic in origin and that they likely formed in the presence of vegetation and rainfall typical of a glacial climate. Their isotopic composition differs markedly from that of carbonate associated with nearby springs. The regional water table therefore remained below the level of Trench 14 during the time that the carbonates and silica precipitated, a period probably covering parts of at least the last 300,000 years. PMID:17818282

  1. Feeding ecology of harbour porpoises: stable isotope anlaysis of carbon and nitrogen in muscle and bone

    NARCIS (Netherlands)

    Jansen, O.E.; Aarts, G.M.; Das, K.; Lepoint, G.; Michel, L.; Reijnders, P.J.H.

    2012-01-01

    Harbour porpoises are the most common small cetaceans in the North Sea and Dutch coastal waters. To study their trophic level and feeding location, stable carbon and nitrogen isotope ratios (d13C and d15N) were analysed in muscle and bone samples collected from 157 porpoises stranded along the Dutch

  2. ANALYTICAL EMPLOYMENT OF STABLE ISOTOPES OF CARBON, NITROGEN, OXYGEN AND HYDROGEN FOR FOOD AUTHENTICATION

    Directory of Open Access Journals (Sweden)

    E. Novelli

    2011-04-01

    Full Text Available Stable isotopes of carbon, nitrogen, oxygen and hydrogen were used for analytical purposes for the discrimination of the type of production (farming vs. fishing in the case of sea bass and for geographical origin in the case of milk. These results corroborate similar experimental evidences and confirm the potential of this analytical tool to support of food traceability.

  3. Authenticity and Traceability of Vanilla Flavors by Analysis of Stable Isotopes of Carbon and Hydrogen

    DEFF Research Database (Denmark)

    Hansen, Anne-Mette Sølvbjerg; Fromberg, Arvid; Frandsen, Henrik Lauritz

    2014-01-01

    . The authenticity of the flavor compound vanillin was evaluated on the basis of measurements of ratios of carbon stable isotopes (delta C-13). It was found that results of delta C-13 for vanillin extracted from Vanilla planifolia and Vanilla tahitensis were significantly different (t test) and that it was possible...... to differentiate these two groups of natural vanillin from vanillin produced otherwise. Vanilla flavors were also analyzed for ratios of hydrogen stable isotopes (delta H-2). A graphic representation of delta C-13 versus delta H-2 revealed that vanillin extracted from pods grown in adjacent geographic origins...

  4. USE OF STABLE CARBON ISOTOPE RATIOS OF FATTY ACIDS TO EVALUATE MICROBIAL CARBON SOURCES IN TERRESTRIAL ENVIRONMENTS

    Science.gov (United States)

    We use measurements of the concentration and stable carbon isotopic ratio (D 13C) of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels and microbial carbon source. We found that intensive sugar cane cultivation leads to ...

  5. Molecular, radioactive and stable carbon isotope characterization of estuarine particulate organic matter

    OpenAIRE

    Megens, L.; van der Plicht, J.; De Leeuw, JW; Leeuw, Jan W. de; Mook, W.G.

    1998-01-01

    Organic matter in sediments and suspended matter is a complex mixture of constituents with different histories, sources and stabilities. To study these components in a suspended matter sample from the Ems-Dollard Estuary, we used combined molecular analysis with pyrolysis/gas chromatography/mass spectrometry and stable and radioactive carbon isotope analyses of the bulk and separated chemical fractions. Carbohydrates and proteins, ca. 50% of the total organic carbon (TOC), are much younger th...

  6. Effect of Different Carbon Substrates on Nitrate Stable Isotope Fractionation During Microbial Denitrification

    DEFF Research Database (Denmark)

    Wunderlich, Anja; Meckenstock, Rainer; Einsiedl, Florian

    2012-01-01

    .1 ± 0.8‰; ε18O, −23.7 ± 1.8‰ to −19.9 ± 0.8‰). The observed isotope effects did not depend on the growth kinetics which were similar for the three types of electron donors. We suggest that different carbon sources change the observed isotope enrichment factors by changing the relative kinetics of......-labeled water and 18O-labeled nitrite were added to the microcosm experiments to study the effect of putative backward reactions of nitrite to nitrate on the stable isotope fractionation. We found no evidence for a reverse reaction. Significant variations of the stable isotope enrichment factor ε were observed...

  7. Determination of the geographical origin of Chinese teas based on stable carbon and nitrogen isotope ratios

    Institute of Scientific and Technical Information of China (English)

    Long ZHANG; Jia-rong PAN; Cheng ZHU

    2012-01-01

    The objective of this study was to investigate the geographical origin of Chinese teas using carbon and nitrogen stable isotope ratio technology.The results showed that inter-provincial dispersion of teas in Guangdong (GD),Guangxi (GX),Hainan (HA),Fujian (F J),Shandong (SD),Sichuan (SC),Chongqing (CQ),and Henan (HN) provinces was high,while in Zhejiang (ZJ),Hubei (HB),Yunnan (YN),and Anhui (AH) provinces,it was low.Tea samples from GD,GX,HA,and FJ provinces were clustered in one group and separated from those from AH and HB provinces.Thus,carbon and nitrogen stable isotope ratio technology could discriminate teas from among some provinces of China,but not from among others.Better separation might be obtained with a combination of isotopic ratios and other indexes,such as elemental data and organic components.

  8. Geochemistry of carbon stable isotopes in the sea

    International Nuclear Information System (INIS)

    This paper describes geochemical process which affect the distribution in the sea of the 13C/12C ratio of total inorganic dissolved CO2; synthesis of the biomass and respiratory phenomena; oxidation of organic matter; dissolution of carbonates; run off waters; exchange of CO2 between sea and atmosphere. Some applications to the paleoclimatology are presented. (author)

  9. 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...

  10. 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

  11. Mixing of water in a carbonate aquifer, southern Italy, analysed through stable isotope investigations

    Directory of Open Access Journals (Sweden)

    Petrella Emma

    2013-01-01

    Full Text Available Mixing of water was analysed in a carbonate aquifer, southern Italy, through stable isotope investigations (18O,δ2H. The input signal (rainwater was compared with the isotopic content of a 35-meter groundwater vertical prof ile, over a 1-year period. Within the studied aquifer, recharge and f low are diffuse in a well-connected f issure network.At the test site, the comparison between input and groundwater isotopic signals illustrates that no eff icient mixing takes place in the whole unsaturated zone, between the fresh inf iltration water and the stored water.When analysing the stable isotope composition of groundwater, signif icant variations were observed above the threshold elevation of 1062 m asl, while a nearly constant composition was observed below the same threshold. Thus, temporal variations in stable isotope composition of rainwater are completely attenuated just in the deeper phreatic zone.On the whole, taking into consideration also the results of previous studies in the same area, the investigations showed that physical characteristics of the carbonate bedrock, as well as aquifer heterogeneity, are factors of utmost importance in inf luencing the complete mixing of water. These f indings suggest a more complex scenario at catchment scale.

  12. 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.

  13. 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.

  14. Tracking Seasonal Habitats Using Carbon and Nitrogen Stable Isotopes of Osprey Primary Flight Feathers

    Science.gov (United States)

    Velinsky, D.; Zelanko, P.; Rice, N.

    2011-12-01

    The majority of bird migration studies use the latitudinal precipitation effect of hydrogen and oxygen stable isotopes of feathers to determine wintering and breeding grounds. Few studies have considered carbon and nitrogen stable isotopes to accomplish the same goal; exploiting the variation in dietary constitutes throughout yearly migration cycles. Also, there is no standard procedure of feather sampling; some use body, while others use wing feathers. This sampling discrepancy is not an issue for most migratory species since the majority of birds molt completely in one location, i.e. wintering verse breeding ground. Large birds of prey however, have a continuous molt that may last years, growing feathers on their breeding and wintering grounds. Therefore, a stable isotopic study of Osprey could not randomly sample feathers because it is impossible to know where individual feathers were grown. Here we present an in depth study of carbon and nitrogen stable isotopes from Mid-Atlantic Osprey primary flight feathers. Not only did we observe three signatures indicating the breeding ground and two distinct wintering grounds, we recorded dietary seasonality shifts within 2 to 3 year olds that remain on the wintering grounds for multiple years.

  15. Variability of carbonate diagenesis in equatorial Pacific sediments deduced from radiogenic and stable Sr isotopes

    Science.gov (United States)

    Voigt, Janett; Hathorne, Ed C.; Frank, Martin; Vollstaedt, Hauke; Eisenhauer, Anton

    2015-01-01

    The recrystallisation (dissolution-precipitation) of carbonate sediments has been successfully modelled to explain profiles of pore water Sr concentration and radiogenic Sr isotope composition at different locations of the global ocean. However, there have been few systematic studies trying to better understand the relative importance of factors influencing the variability of carbonate recrystallisation. Here we present results from a multi-component study of recrystallisation in sediments from the Integrated Ocean Drilling Program (IODP) Expedition 320/321 Pacific Equatorial Age Transect (PEAT), where sediments of similar initial composition have been subjected to different diagenetic histories. The PEAT sites investigated exhibit variable pore water Sr concentrations gradients with the largest gradients in the youngest sites. Radiogenic Sr isotopes suggest recrystallisation was relative rapid, consistent with modelling of other sediment columns, as the 87Sr/86Sr ratios are indistinguishable (within 2σ uncertainties) from contemporaneous seawater 87Sr/86Sr ratios. Bulk carbonate leachates and associated pore waters of Site U1336 have lower 87Sr/86Sr ratios than contemporaneous seawater in sediments older than 20.2 Ma most likely resulting from the upward diffusion of Sr from older recrystallised carbonates. It seems that recrystallisation at Site U1336 may still be on-going at depths below 102.5 rmcd (revised metres composite depth) suggesting a late phase of recrystallisation. Furthermore, the lower Sr/Ca ratios of bulk carbonates of Site U1336 compared to the other PEAT sites suggest more extensive diagenetic alteration as less Sr is incorporated into secondary calcite. Compared to the other PEAT sites, U1336 has an inferred greater thermal gradient and a higher carbonate content. The enhanced thermal gradient seems to have made these sediments more reactive and enhanced recrystallisation. In this study we investigate stable Sr isotopes from carbonate-rich deep

  16. Boron Isotope Intercomparison Project (BIIP): Development of a new carbonate standard for stable isotopic analyses

    Science.gov (United States)

    Gutjahr, Marcus; Bordier, Louise; Douville, Eric; Farmer, Jesse; Foster, Gavin L.; Hathorne, Ed; Hönisch, Bärbel; Lemarchand, Damien; Louvat, Pascale; McCulloch, Malcolm; Noireaux, Johanna; Pallavicini, Nicola; Rodushkin, Ilia; Roux, Philippe; Stewart, Joseph; Thil, François; You, Chen-Feng

    2014-05-01

    Boron consists of only of two isotopes with a relatively large mass difference (~10 %). It is also volatile in acidic media and prone to contamination during analytical treatment. Nevertheless, an increasing number of isotope laboratories are successfully using boron isotope compositions (expressed in δ11B) in marine biogenic carbonates to reconstruct seawater pH. Recent interlaboratory comparison efforts [1] highlighted the existence of a relatively high level of disagreement between laboratories when measuring such material, so in order to further strengthen the validity of this carbonate system proxy, appropriate reference materials need to be urgently characterised. We describe here the latest results of the Boron Isotope Intercomparison Project (BIIP) where we aim to characterise the boron isotopic composition of two marine carbonates: Japanese Geological Survey carbonate standard materials JCp-1 (coral porites) [2] and JCt-1 (Giant Clam) [3]. This boron isotope interlaboratory comparison study has two aims: (i) to assess to what extent chemical pre-treatment, aimed at removing organic material, can influence the resulting carbonate δ11B; (ii) to determine the isotopic composition of the two reference materials with a number of analytical techniques to provide the community with reference δ11B values for JCp-1 and JCt-1 and to further explore any differences related to analytical technique. In total eight isotope laboratories participated, of which one determined δ11B via negative thermal ionisation mass spectrometry (NTIMS) and seven used multi collector inductively coupled plasma mass spectrometry (MC-ICPMS). For the latter several different introduction systems and chemical purification methods were used. Overall the results are strikingly consistent between the participating labs. The oxidation of organic material slightly lowered the median δ11B by ~0.1 ‰ for both JCp-1 and JCt-1, while the mean δ11B of all labs for both standards was lowered by 0

  17. Determination of the coefficient of iodine absorption carbon materials adsorber ventilation NPP using stable isotopes

    International Nuclear Information System (INIS)

    Submitted by nuclear-physical methods of determining the coefficient of absorption of iodine carbon materials using stable isotopes of iodine. Designed and created by pumping and measuring iodine content units. The processes of dynamic sorption of iodine on industrial carbon adsorbents studied the possibility of determining the iodine content of nuclear-physical methods and presents the metrological characteristics x-ray method. Application methods allow for the certification of carbon adsorbents gas cleaning systems and improve the safety of nuclear power plant operation

  18. Organic carbon and nitrogen stable isotopes in the intertidal sediments from the Yangtze Estuary, China

    International Nuclear Information System (INIS)

    The natural isotopic compositions and C/N elemental ratios of sedimentary organic matter were determined in the intertidal flat of the Yangtze Estuary. The results showed that the ratios of carbon and nitrogen stable isotopes were respectively -29.8 per mille to - 26.0 per mille and 1.6 per mille -5.5 per mille in the flood season (July), while they were -27.3 per mille to - 25.6 per mille and 1.7 per mille -7.8 per mille in the dry season (February), respectively. The δ 13C signatures were remarkably higher in July than in February, and gradually increased from the freshwater areas to the brackish areas. In contrast, there were relatively complex seasonal and spatial changes in stable nitrogen isotopes. It was also reflected that δ 15N and C/N compositions had been obviously modified by organic matter diagenesis and biological processing, and could not be used to trace the sources of organic matter at the study area. In addition, it was considered that the mixing inputs of terrigenous and marine materials generally dominated sedimentary organic matter in the intertidal flat. The contribution of terrigenous inputs to sedimentary organic matter was roughly estimated according to the mixing balance model of stable carbon isotopes

  19. Stable carbon isotopes of invertebrate remains: do they reveal past methane release from lakes?

    OpenAIRE

    van Hardenbroek-van Ammerstol, M. R.

    2010-01-01

    Lakes are a source of methane, an important greenhouse gas in the atmosphere. In order to understand increasing methane emissions in the present, it is important to study the variations of methane release during past periods of climate change. However, records of methane release from lakes over time scales longer than a few years are extremely rare. In this thesis a method is explored to reconstruct past methane availability in lakes based on the stable carbon isotope composition (delta 13C) ...

  20. 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...

  1. Mechanisms controlling the carbon stable isotope composition of phytoplankton in karst reservoirs

    OpenAIRE

    Baoli Wang; Cong-Qiang Liu; Xi Peng; Fushun Wang

    2013-01-01

    In order to systematically understand the mechanisms controlling the carbon stable isotope composition of phytoplankton (δ13CPHY)in freshwater ecosystems, seasonal changes in δ13CPHY and related environmental factors were determined in karst reservoirs from the Wujiang river basin, China. Substantial and systematic differences within seasons and reservoirs were observed for δ13CPHY, which ranged from -39.2‰ to -15.1‰. An increase in water temperature triggered fast growth of phytoplankton whi...

  2. Carbon Biogeochemistry: A Stable Isotope Approach to Trophic Dynamics in an Indian Coastal Ecosystem

    Science.gov (United States)

    Mathukumalli, B.; Alagappan, R.

    2005-12-01

    Stable isotope(δ13C & δ15N) approach was applied to understand carbon biogeochemistry and trophic dynamics in an Indian coastal mangrove wetland. The δ13C and δ15N values of potential nutrient sources (mangrove plant leaves, lichen, sediment and suspended material) and in seven species of consumers (invertebrates) were measured. The value of δ13C and δ15N isotopes of different potential nutrient sources and the consumers determine the sources of nutrients for the invertebrate consumer community of the mangrove. There is a significant variation in the stable carbon in the nutrient sources; however, δ15N signatures were not significantly different among the different potential nutrient sources. Organic matter in the sediments under the mangrove vegetation was characterized by relatively negatively fractionated and moderately high C:N ratios, indicating that mangrove derived organic matter was the principal diet source for the invertebrate consumer communities in the mangrove ecosystem. Invertebrates in the mangrove showed a wide range of δ13C signatures and are enriched relative to the mangrove leaf stable isotope values. Micro-environmental differences certainly drive the variability in the nutrient sources and consumable nature among the different regions of the ecosystem. Therefore, further research is needed to determine whether carbon assimilation is different from one zone to another.

  3. Stable carbon isotope depth profiles and soil organic carbon dynamics in the lower Mississippi Basin

    Science.gov (United States)

    Wynn, J.G.; Harden, J.W.; Fries, T.L.

    2006-01-01

    Analysis of depth trends of 13C abundance in soil organic matter and of 13C abundance from soil-respired CO2 provides useful indications of the dynamics of the terrestrial carbon cycle and of paleoecological change. We measured depth trends of 13C abundance from cropland and control pairs of soils in the lower Mississippi Basin, as well as the 13C abundance of soil-respired CO2 produced during approximately 1-year soil incubation, to determine the role of several candidate processes on the 13C depth profile of soil organic matter. Depth profiles of 13C from uncultivated control soils show a strong relationship between the natural logarithm of soil organic carbon concentration and its isotopic composition, consistent with a model Rayleigh distillation of 13C in decomposing soil due to kinetic fractionation during decomposition. Laboratory incubations showed that initially respired CO 2 had a relatively constant 13C content, despite large differences in the 13C content of bulk soil organic matter. Initially respired CO2 was consistently 13C-depleted with respect to bulk soil and became increasingly 13C-depleted during 1-year, consistent with the hypothesis of accumulation of 13C in the products of microbial decomposition, but showing increasing decomposition of 13C-depleted stable organic components during decomposition without input of fresh biomass. We use the difference between 13C / 12C ratios (calculated as ??-values) between respired CO 2 and bulk soil organic carbon as an index of the degree of decomposition of soil, showing trends which are consistent with trends of 14C activity, and with results of a two-pooled kinetic decomposition rate model describing CO2 production data recorded during 1 year of incubation. We also observed inconsistencies with the Rayleigh distillation model in paired cropland soils and reasons for these inconsistencies are discussed. ?? 2005 Elsevier B.V. All rights reserved.

  4. Stable and radioactive carbon in forest soils of Chhattisgarh, Central India: Implications for tropical soil carbon dynamics and stable carbon isotope evolution

    Science.gov (United States)

    Laskar, A. H.; Yadava, M. G.; Ramesh, R.

    2016-06-01

    Soils from two sites viz. Kotumsar and Tirathgarh, located ∼5 km apart in a tropical reserve forest (18°52‧N, 81°56‧E) in central India, have been explored for soil organic carbon (SOC) content, its mean residence time (MRT) and the evolution of stable carbon isotopic composition (δ13C). SOC stocks in the upper 30 cm of soil layers are ∼5.3 kg/m2 and ∼3.0 kg/m2; in the upper 110 m are ∼10.7 kg/m2 and ∼7.8 kg/m2 at Kotumsar and Tirathgarh, respectively. SOC decreases with increasing depth. Bomb carbon signature is observed in the upper ∼10 cm. Organic matters in the top soil layers (0-10 cm) have MRTs of the order of a century which increases gradually with depths, reaching 3500-5000 yrs at ∼100 cm. δ13C values of SOC increase with depth, the carbon isotopic fractionation is obtained to be -1.2‰ and -3‰ for soils at Kotumsar and Tirathgarh, respectively, confirmed using Rayleigh isotopic fractionation model. The evolution of δ13C in soils was also studied using a modified Rayleigh fractionation model incorporating a continuous input into the reservoir: the depth profiles of δ13C for SOC show that the input organic matter from surface into the deeper soil layers is either insignificant or highly labile and decomposes quite fast in the top layers, thus making little contribution to the residual biomasses of the deeper layers. This is an attempt to understand the distillation processes that take place in SOC, assess the extent of decomposition by microbes and effect of percolation of fresh organic matter into dipper soil layers which are important for stable isotope based paleoclimate and paleovegetation reconstruction and understanding the dynamics of organic carbon in soils.

  5. Compositional and stable carbon isotopic fractionation during non-autocatalytic thermochemical sulfate reduction by gaseous hydrocarbons

    Science.gov (United States)

    Xia, Xinyu; Ellis, Geoffrey S.; Ma, Qisheng; Tang, Yongchun

    2014-01-01

    The possibility of autocatalysis during thermochemical sulfate reduction (TSR) by gaseous hydrocarbons was investigated by examination of previously reported laboratory and field data. This reaction was found to be a kinetically controlled non-autocatalytic process, and the apparent lack of autocatalysis is thought to be due to the absence of the required intermediate species. Kinetic parameters for chemical and carbon isotopic fractionations of gaseous hydrocarbons affected by TSR were calculated and found to be consistent with experimentally derived values for TSR involving long-chain hydrocarbons. Model predictions based on these kinetic values indicate that TSR by gaseous hydrocarbon requires high-temperature conditions. The oxidation of C2–5 hydrocarbons by sulfate reduction is accompanied by carbon isotopic fractionation with the residual C2–5 hydrocarbons becoming more enriched in 13C. Kinetic parameters were calculated for the stable carbon isotopic fractionation of gaseous hydrocarbons that have experienced TSR. Model predictions based on these kinetics indicate that it may be difficult to distinguish the effects of TSR from those of thermal maturation at lower levels of hydrocarbon oxidation; however, unusually heavy δ13C2+ values (>−10‰) can be diagnostic of high levels of conversion (>50%). Stoichiometric and stable carbon isotopic data show that methane is stable under the investigated reaction conditions and is likely a product of TSR by other gaseous hydrocarbons rather than a significant reactant. These results indicate that the overall TSR reaction mechanism for oxidation of organic substrates containing long-chain hydrocarbons involves three distinct phases as follows: (1) an initial slow and non-autocatalytic stage characterized by the reduction of reactive sulfate by long-chain saturated hydrocarbons; (2) a second autocatalytic reaction phase dominated by reactions involving reduced sulfur species and partially oxidized hydrocarbons; (3

  6. Stable carbon isotope fractionation during the biodegradation of lambda-cyhalothrin

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Xiaoli [MOE Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Department of Environmental Engineering, Quzhou University, Quzhou 324000 (China); Xu, Zemin [MOE Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Zhang, Xichang [Laboratory for Teaching in Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Yang, Fangxing, E-mail: fxyang@zju.edu.cn [MOE Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Department of Effect-Directed Analysis, Helmholtz Centre for Environmental Research — UFZ, Leipzig 04318 (Germany)

    2015-11-01

    In this study, the microbial degradation of lambda-cyhalothrin in soil was investigated using compound-specific stable isotope analysis. The results revealed that lambda-cyhalothrin was biodegraded in soil under laboratory conditions. The half-lives of lambda-cyhalothrin were determined to be 49 and 161 days in non-sterile and sterile soils spiked with 2 mg/kg lambda-cyhalothrin and 84 and 154 days in non-sterile and sterile soils spiked with 10 mg/kg lambda-cyhalothrin, respectively. The biodegradation of lambda-cyhalothrin resulted in carbon isotope fractionation, which shifted from − 29.0‰ to − 26.5‰ in soil spiked with 2 mg/kg lambda-cyhalothrin, and to − 27.5‰ with 10 mg/kg lambda-cyhalothrin. A relationship was established between the stable carbon isotope fraction and the residual concentrations of lambda-cyhalothrin by the Rayleigh equation in which the carbon isotope enrichment factor ε of the microbial degradation of lambda-cyhalothrin in the soil was calculated as − 2.53‰. This study provides an approach to quantitatively evaluate the biodegradation of lambda-cyhalothrin in soil in field studies. - Highlights: • Abiotic and biotic degradation of lambda-cyhalothrin were observed in soil. • Biodegradation of lambda-cyhalothrin was evaluated by CSIA. • Biodegradation of lambda-cyhalothrin leads to carbon isotope fractionation. • An enrichment factor ε of lambda-cyhalothrin was determined as − 2.53‰.

  7. Arctic herbivore diet can be inferred from stable carbon and nitrogen isotopes in C3 plants, faeces and wool

    DEFF Research Database (Denmark)

    Kristensen, Ditte; Kristensen, Erik; Forchhammer, Mads C.;

    2011-01-01

    for studying arctic herbivore diets. In this study, we examined the potential of both stable carbon and nitrogen isotopes to reconstruct the diet of an arctic herbivore, here the muskox (Ovibos moschatus (Zimmermann, 1780)), in northeast Greenland. The isotope composition of plant communities and functional......% graminoids and up to 20% willows. In conclusion, the diet composition of an arctic herbivore can indeed be inferred from stable isotopes in arctic areas, despite the lack of C4 plants...

  8. Stable isotope studies

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  9. Stable isotope studies

    International Nuclear Information System (INIS)

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs

  10. Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment

    Science.gov (United States)

    Alperin, M. J.; Blair, Neal E.; Albert, D. B.; Hoehler, T. M.; Martens, C. S.

    1993-01-01

    The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionation associated with methane oxidation. The importance of each factor was evaluated by monitoring stable carbon isotope ratios in methane produced by a sediment microcosm. Methane did not accumulate during the initial 42-day period when sediment contained sulfate, indicating little methane production from 'noncompetitive' substrates. Following sulfate depletion, methane accumulation proceeded in three distinct phases. First, CO2 reduction was the dominant methanogenic pathway and the isotopic composition of the methane produced ranged from -80 to -94 per thousand. The acetate concentration increased during this phase, suggesting that acetoclastic methanogenic bacteria were unable to keep pace with acetate production. Second, acetate fermentation became the dominant methanogenic pathway as bacteria responded to elevated acetate concentrations. The methane produced during this phase was progressively enriched in C-13, reaching a maximum delta(C-13) value of -42 per thousand. Third, the acetate pool experienced a precipitous decline from greater than 5 mM to less than 20 micro-M and methane production was again dominated by CO2 reduction. The delta(C-13) of methane produced during this final phase ranged from -46 to -58 per thousand. Methane oxidation concurrent with methane production was detected throughout the period of methane accumulation, at rates equivalent to 1 to 8 percent of the gross methane production rate. Thus methane oxidation was too slow to have significantly modified the isotopic signature of methane. A comparison of microcosm and field data suggests that similar microbial interactions may control seasonal variability in the isotopic composition of methane

  11. Stable carbon and radiocarbon isotope compositions of particle size fractions to determine origins of sedimentary organic matter in an estuary

    NARCIS (Netherlands)

    Megens, L; van der Plicht, J; de Leeuw, JW; Smedes, F; Altabet, M.

    2002-01-01

    Stable and radioactive carbon isotopic compositions of particle size fractions of a surface sediment from the Ems-Dollard estuary vary considerably with particle size. The organic material in the fine fractions (

  12. Mechanisms controlling the carbon stable isotope composition of phytoplankton in karst reservoirs

    Directory of Open Access Journals (Sweden)

    Baoli Wang

    2013-02-01

    Full Text Available In order to systematically understand the mechanisms controlling the carbon stable isotope composition of phytoplankton (δ13CPHYin freshwater ecosystems, seasonal changes in δ13CPHY and related environmental factors were determined in karst reservoirs from the Wujiang river basin, China. Substantial and systematic differences within seasons and reservoirs were observed for δ13CPHY, which ranged from -39.2‰ to -15.1‰. An increase in water temperature triggered fast growth of phytoplankton which assimilated more dissolved inorganic carbon (DIC, resulting in the increase of δ13CPHY, δ13CDIC and pH. When the concentration of dissolved carbon dioxide (CO2 was less than 10 mmol L–1, phytoplankton shifted to using HCO3– as a carbon source. This resulted in the sharp increase of δ13CPHY. The carbon stable isotope composition of phytoplankton tended to decrease with the increase of Bacillariophyta, which dominated in January and April, but tended to increase with the increase of Chlorophyta and Dinophyta, which dominated in July. Multiple regression equations suggested that the influence of biological factors such as taxonomic difference on δ13CPHY could be equal or more important than that of physical and chemical factors. Thus, the effect of taxonomic differences on δ13CPHY must be considered when explaining the δ13C of organic matter in lacustrine ecosystem.

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

    Science.gov (United States)

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

    2008-09-01

    Soil samples were collected from an experimental paddy field with long-term (26 years) fertilization in Taihu Lake region of Jiangsu Province to study the effects of different fertilization on the organic carbon distribution and stable carbon isotope natural abundance (delta 13C) in the soil profile, and on the humus composition. The results showed that long-term fertilization increased the organic carbon content in top soil significantly, and there was a significantly negative exponential correlation between soil organic carbon content and soil depth (P humus (humin) was the main humus composition in the soil, occupying 50% or more, and the rest were loosely and stably combined humus. Long-term fertilization increased the content of loosely combined humus and the ratio of humic acid (HA) to fulvic acid (FA).

  14. Technical Note: Constraining stable carbon isotope values of microphytobenthos (C3 photosynthesis) in the Arctic for application to food web studies

    OpenAIRE

    Oxtoby, L. E.; Mathis, J. T.; Juranek, L. W.; M. J. Wooller

    2013-01-01

    Microphytobenthos (MPB) tends to be omitted as a possible carbon source to higher trophic level consumers in high latitude marine food web models that use stable isotopes. Here, we used previously published relationships relating the concentration of aqueous carbon dioxide ([CO2]aq), the stable carbon isotopic composition of dissolved inorganic carbon (DIC) (δ13CDIC), and algal growth rates (μ) to estimate the stable carbon isotop...

  15. Carbon Stable Isotope Analysis of Methylmercury Toxin in Biological Materials by Gas Chromatography Isotope Ratio Mass Spectrometry.

    Science.gov (United States)

    Masbou, Jeremy; Point, David; Guillou, Gaël; Sonke, Jeroen E; Lebreton, Benoit; Richard, Pierre

    2015-12-01

    A critical component of the biogeochemical cycle of mercury (Hg) is the transformation of inorganic Hg to neurotoxic monomethylmercury (CH3Hg). Humans are exposed to CH3Hg by consuming marine fish, yet the origin of CH3Hg in fish is a topic of debate. The carbon stable isotopic composition (δ(13)C) embedded in the methyl group of CH3Hg remains unexplored. This new isotopic information at the molecular level is thought to represent a new proxy to trace the carbon source at the origin of CH3Hg. Here, we present a compound-specific stable isotope analysis (CSIA) technique for the determination of the δ(13)C value of CH3Hg in biological samples by gas chromatography combustion isotope ratio mass spectrometry analysis (GC-C-IRMS). The method consists first of calibrating a CH3Hg standard solution for δ(13)C CSIA. This was achieved by comparing three independent approaches consisting of the derivatization and halogenation of the CH3Hg standard solution. The determination of δ(13)C(CH3Hg) values on natural biological samples was performed by combining a CH3Hg selective extraction, purification, and halogenation followed by GC-C-IRMS analysis. Reference δ(13)C values were established for a tuna fish certified material (ERM-CE464) originating from the Adriatic Sea (δ(13)C(CH3Hg) = -22.1 ± 1.5‰, ± 2 SD). This value is similar to the δ(13)C value of marine algal-derived particulate organic carbon (δ(13)CPOC = -21‰).

  16. Recent planktic foraminifers in the Fram Strait (Arctic Ocean): carbon and oxygen stable isotope composition

    Science.gov (United States)

    Pados, T.; Spielhagen, R. F.; Bauch, D.; Meyer, H.; Segl, M.

    2012-12-01

    In paleoceanographic reconstructions the carbon isotopic compositions (δ13C) of fossil foraminifers refer to, e.g., paleoproductivity and stratification, while oxygen isotopic (δ18O) records provide information about variations in sea surface temperatures and salinities in the past. However, for a correct interpretation of the fossil data it is important to improve our understanding of the correlation between recent oceanic variability and the composition of shells of living calcareous microorganisms. For this, the upper water column and sediment surface in the Fram Strait (Arctic Ocean, 78°50'N, 5°W-8°E) were sampled for planktic foraminifer species Neogloboquadrina pachyderma (sin.) and Turborotalita quinqueloba with a large-diameter multinet and a multicorer, respectively. The δ13C and δ18O values of the shells are compared to the stable isotope composition of the ambient water and to equilibrium calcite values to define the preferred calcification depths of the foraminifers and to determine the factors controlling the isotopic signature of these calcareous microorganisms. The study area was chosen because of its high oceanographic variability: in the eastern Fram Strait the northward flowing West Spitsbergen Current (WSC) carries Atlantic Water, with a thin mixed layer on top, while in the west the upper 200 m consists of cold, low-saline Arctic outflow waters of the East Greenland Current (EGC) and warmer, saline waters of Atlantic origin underneath. Despite this variable oceanographic regime along the studied transect, the stable carbon isotope ratios of the shells do not show major differences according to their horizontal but to their vertical distribution: the δ13C values of N. pachyderma (sin.) from plankton tow samples vary roughly between -1 and -0.1‰ depending on the water depth, while the δ18O values of the tests differ more between the stations.

  17. Lipid correction for carbon stable isotope analysis of deep-sea fishes

    Science.gov (United States)

    Hoffman, Joel C.; Sutton, Tracey T.

    2010-08-01

    Stable isotope analysis of fish tissue can aid studies of deep-sea food webs because sampling difficulties severely limit sample sizes of fish for traditional diet studies. The carbon stable isotope ratio (δ 13C) is widely used in food web studies, but it must be corrected to remove variability associated with varying lipid content in the tissue. A lipid correction has not been determined for any deep-sea fish. These fishes are ideal for studying lipid correction because lipid content varies widely among species. Our objective was to evaluate an application of a mass balance δ 13C correction to a taxonomically diverse group of deep-sea fishes by determining the effect of lipid extraction on the stable isotope ratios, examining the quality of the model parameters derived for the mass balance correction, and comparing the correction to published results. We measured the lipid extraction effect on the nitrogen stable isotope ratio (δ 15N) and δ 13C of muscle tissue from 30 North Atlantic species. Lipid extraction significantly increased tissue δ 15N (+0.66‰) and δ 13C values, but the treatment effect on δ 13C was dependent on C:N, a proxy for lipid content. We compared the lipid-extracted δ 13C to the δ 13C predicted by the mass balance correction using model variables estimated from either all individuals (pooled) or species-by-species or using published values from other species. The correction using the species-by-species approach performed best; however, all three approaches produced corrected values that were generally within 0.5‰ of the measured lipid-free δ 13C and that had a small over-all bias (deep-sea fishes, is similar to that developed for other fishes, and recommend caution when applying a generalized correction to fish with high lipid content (C:N >8).

  18. Stable carbon and hydrogen isotopic fractionations of alkane compounds and crude oil during aerobically microbial degradation

    Institute of Scientific and Technical Information of China (English)

    PENG Xianzhi; ZHANG Gan; CHEN Fanzhong; LIU Guoqing

    2004-01-01

    Normal alkane compounds dodecane, pentadecane, hexadecane, octadecane, tetracosane, isoprenoid alkane pristane and a crude oil sample were aerobically biodegraded with a pure bacterial strain GIM2.5 and white rot fungus Phanerochaete Chrysosporium-1767 to monitor the kinetic fractionation of the molecular stable carbon (δ13C) and hydrogen (δD) isotopes in the course of biodegradation. Both δ13C (V-PDB) and δ D (V-SMOW) remained stable for the standard alkane compounds and n-alkane components (from n-C13 to n-C25) of the crude oil, generally varying in the range of ±0.5‰ and ±5‰ respectively, within the range of the instrumental precisions, especially for those molecularly heavier than n-C16 during microbial degradation. These results indicate that molecular stable carbon and hydrogen isotopic fingerprints can be promising indicators for tracing the sources of petroleum-related contaminants in the environment, especially in the case of severe weathering when they are difficult to be unambiguously identified by the chemical fingerprints alone.

  19. Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

    Directory of Open Access Journals (Sweden)

    Thomas Larsen

    Full Text Available Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13C patterns among amino acids (δ(13CAA could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13CAA patterns in contrast to bulk δ(13C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs.

  20. Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

    Science.gov (United States)

    Larsen, Thomas; Ventura, Marc; Andersen, Nils; O'Brien, Diane M; Piatkowski, Uwe; McCarthy, Matthew D

    2013-01-01

    Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13)C patterns among amino acids (δ(13)CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13)CAA patterns in contrast to bulk δ(13)C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13)CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13)C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13)C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs. PMID:24069196

  1. Stable isotopes labelled compounds

    International Nuclear Information System (INIS)

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  2. Stable carbon isotopic composition of soil organic matter in the karst areas of Southwest China

    Institute of Scientific and Technical Information of China (English)

    ZHU Shufa; LIU Congqiang

    2008-01-01

    This study dealt with the distribution characteristics of soil organic carbon (SOC) and the variation of stable carbon isotopic composition (δ13C values) with depth in six soil profiles, including two soil types and three vegetation forms in the karst areas of Southwest China. The δ13C values of plant-dominant species, leaf litter and soils were measured using the sealed-tube high-temperature combustion method. Soil organic carbon contents of the limestone soil profiles are all above 11.4 g/kg, with the highest value of 71.1 g/kg in the surface soil. However, the contents vary between 2.9 g/kg and 46.0 g/kg in three yellow soil profiles. The difference between the maximum and minimum δ13C values of soil organic matter (SOM) changes from 2.2‰ to 2.9‰ for the three yellow soil profiles. But it changes from 0.8‰ to 1.6‰ for the limestone soil profiles. The contrast research indicated that there existed significant difference in vertical patterns of organic carbon and δ13C values of SOM between yellow soil and limestone soil. This difference may reflect site-specific factors, such as soil type, vegetation form, soil pH value, and clay content, etc., which control the contents of different organic components comprising SOM and soil carbon turnover rates in the profiles. The vertical variation patterns of stable carbon isotope in SOM have a distinct regional character in the karst areas.

  3. Stable carbon isotopes as indicators for micro-geomorphic changes in palsa peats

    Directory of Open Access Journals (Sweden)

    C. Alewell

    2011-01-01

    Full Text Available Palsa peats are unique northern ecosystems formed under an arctic climate and characterized by an unique biodiversity and ecology. The stability of the palsas are seriously threatened by climate warming which will change the permafrost dynamic and results in degradation of the mires. We used stable carbon isotope depth profiles in two palsa mires of Northern Sweden to track environmental change during the formation of the mires. Carbon isotope13C depth profile of the yet undisturbed mire Storflaket indicated very low to no degradation of the peat in the water saturated depressions (hollows but increased rates of anaerobic degradation at the Stordalen site. The latter might be induced by degradation of the permafrost cores in the uplifted areas (hummocks and subsequent braking and submerging of the hummock peat into the hollows due to climate warming. Carbon isotope depth profiles of hummocks indicated a turn from aerobic mineralisation to anaerobic degradation at a peat depth between 4 to 25 cm. The age of these turning point was 14C dated between 150 and 670 years and could thus not be caused by anthropogenically induced climate change. We found the uplifting of the hummocks due to permafrost heave the most likely explanation for our findings. We thus concluded that differences in carbon isotope profiles of the hollows might point to the disturbance of the mires due to climate warming or due to differences in hydrology. The characteristic profiles of the hummocks are indicators for micro-geomorphic change during permafrost up heaving.

  4. Stable Isotope Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...

  5. 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.

  6. Simultaneous Analysis of Nitrogen, Carbon and Sulfur Stable Isotopes and Concentrations in Organics and Soils

    Science.gov (United States)

    Mambelli, S.; Brooks, P. D.; Sutka, R.; Hughes, S.; Finstad, K. M.; Pakes, M. J.; Dawson, T. E.

    2014-12-01

    To date, analysis of diet, food web complexities, biogeochemical cycles, and ecosystem functioning have largely focused on using variation in carbon (C) and nitrogen (N) stable isotope ratios. This is because a great deal is understood about what leads to this variation and because the dual stable isotope analysis of these two elements using continuous flow isotope ratio mass spectrometry (IRMS) is now commonplace. However, the aforementioned studies may all greatly benefit from the additional information one can get from also having sulfur (S) stable isotopes ratio data. Until very recently the analysis of δ34S has traditionally required an additional and often more difficult analytical procedure. Here, we report on the development of a new method that simultaneously analyzes the elemental and isotopic composition of N, C and S in a single sample. The new commercially available instrument includes a modified NCS elemental analyzer in line with an IRMS outfitted with 100 volt AD converters for wide dynamic range. We tested, and modified, this instrument to achieve maximum accuracy and precision for the isotopic measurements of all three elements. We found that the original design needed improvements to achieve our goals by: a) including a component (originally designed for trapping water) as buffer to reduce S memory and obtain reliable δ34S analysis; b) adding an external furnace for complete reduction of nitrogen oxides to N2 gas for accurate δ15N; c) adding a magnesium perchlorate water trap immediately after the reduction tube to minimize any water condensation that could also influence S memory. We analyzed a selection of organic materials and soils with approximately a 1:2 standards versus unknowns ratio per run. Using this NCS set-up, the precision of the N and C isotopic measurements was comparable to the one usually attained in NC mode alone (standard deviation of ± 0.13 δ15N in the range 30 to 400 µg N, and of ± 0.12 δ13C in the range 0.20 to 4 mg

  7. Authenticity and traceability of vanilla flavors by analysis of stable isotopes of carbon and hydrogen.

    Science.gov (United States)

    Hansen, Anne-Mette Sølvbjerg; Fromberg, Arvid; Frandsen, Henrik Lauritz

    2014-10-22

    Authenticity and traceability of vanilla flavors were investigated using gas chromatography-isotope ratio mass spectrometry (GC-IRMS). Vanilla flavors produced by chemical synthesis (n = 2), fermentation (n = 1), and extracted from two different species of the vanilla orchid (n = 79) were analyzed. The authenticity of the flavor compound vanillin was evaluated on the basis of measurements of ratios of carbon stable isotopes (δ(13)C). It was found that results of δ(13)C for vanillin extracted from Vanilla planifolia and Vanilla tahitensis were significantly different (t test) and that it was possible to differentiate these two groups of natural vanillin from vanillin produced otherwise. Vanilla flavors were also analyzed for ratios of hydrogen stable isotopes (δ(2)H). A graphic representation of δ(13)C versus δ(2)H revealed that vanillin extracted from pods grown in adjacent geographic origins grouped together. Accordingly, values of δ(13)C and δ(2)H can be used for studies of authenticity and traceability of vanilla flavors. PMID:25266169

  8. Authenticity and traceability of vanilla flavors by analysis of stable isotopes of carbon and hydrogen.

    Science.gov (United States)

    Hansen, Anne-Mette Sølvbjerg; Fromberg, Arvid; Frandsen, Henrik Lauritz

    2014-10-22

    Authenticity and traceability of vanilla flavors were investigated using gas chromatography-isotope ratio mass spectrometry (GC-IRMS). Vanilla flavors produced by chemical synthesis (n = 2), fermentation (n = 1), and extracted from two different species of the vanilla orchid (n = 79) were analyzed. The authenticity of the flavor compound vanillin was evaluated on the basis of measurements of ratios of carbon stable isotopes (δ(13)C). It was found that results of δ(13)C for vanillin extracted from Vanilla planifolia and Vanilla tahitensis were significantly different (t test) and that it was possible to differentiate these two groups of natural vanillin from vanillin produced otherwise. Vanilla flavors were also analyzed for ratios of hydrogen stable isotopes (δ(2)H). A graphic representation of δ(13)C versus δ(2)H revealed that vanillin extracted from pods grown in adjacent geographic origins grouped together. Accordingly, values of δ(13)C and δ(2)H can be used for studies of authenticity and traceability of vanilla flavors.

  9. Stable carbon isotope composition of monoterpanes in essential oils and crude oils

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Twenty-five monoterpanes from six types of essential oils and hydrogenated turpentine oil have been identified and their stable carbon isotope composition determined.Monoterpanes in essential oils sourced from terrestrial higher plants display a δ13C value in the range of-34‰-26‰,and mostly between-29‰ and-27‰.The δ13C value of any single monoterpane is very consistent in different essential oils.Acyclic monoterpanes show closer isotope composition between-28.6‰ and-26.2‰,with an average value of-27.7‰.In contrast,the isotope composition of cyclic monoterpanes is more scattered with an average value of-28.6‰.Isotopic fractionation with 13C enrichment has been observed during both artificial and geological hydrogenation of monoterpenoids to monoterpanes,and this is more obvious for the acyclic monoterpenoids.In addition to higher plants,acyclic monoterpane 2,6-dimethylheptane in crude oil can also be originated from other organic inputs.

  10. Carbon and Oxygen Stable Isotope Measurements of Martian Atmospheric CO2 by the Phoenix Lander

    Science.gov (United States)

    Niles, Paul B.; Boynton, W. V.; Hoffman, J. H.; Ming, D. W.; Hamara, D.

    2010-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars [1]. The isotopic composition of the martian atmosphere has been measured using a number of different methods (Table 1), however a precise value (carbonates in martian meteorites [2-4] it has been proposed that the martian atmosphere was enriched in 13C [8]. This was supported by measurements of trapped CO2 gas in EETA 79001[2] which showed elevated Delta(sup 13)C values (Table 1). More recently, Earth-based spectroscopic measurements of the martian atmosphere have measured the martian CO2 to be depleted in C-13 relative to CO2 in the terrestrial atmosphere[ 7, 9-11]. The Thermal and Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander [12] included a magnetic-sector mass spectrometer (EGA) [13] which had the goal of measuring the isotopic composition of martian atmospheric CO2 to within 0.5%. The mass spectrometer is a miniature instrument intended to measure both the martian atmosphere as well as gases evolved from heating martian soils.

  11. A versatile method for simultaneous stable carbon isotope analysis of DNA and RNA nucleotides by liquid chromatography/isotope ratio mass spectrometry

    NARCIS (Netherlands)

    Moerdijk-Poortvliet, T.C.W.; Brasser, J.; de Ruiter, G.; Houtekamer, M.; Bolhuis, H.; Stal, L.J.; Boschker, H.T.S.

    2014-01-01

    RATIONALELiquid chromatography/isotope ratio mass spectrometry (LC/IRMS) is currently the most accurate and precise technique for the measurement of compound-specific stable carbon isotope ratios (C-13/C-12) in biological metabolites, at their natural abundance. However, until now this technique cou

  12. Determination of the origin of dissolved inorganic carbon in groundwater around a reclaimed landfill in Otwock using stable carbon isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Porowska, Dorota, E-mail: dorotap@uw.edu.pl

    2015-05-15

    Highlights: • Research showed the origin of DIC in the groundwater around a reclaimed landfill. • Carbon isotope was used to evaluate the contributions of carbon from different sources. • The leachate-contaminated water was isotopically distinct from the natural groundwater. • DIC in the natural groundwater comes from organic matter and dissolution of carbonates. • In the contaminated water, DIC comes from organic matter in the aquifer and landfill. - Abstract: Chemical and isotopic analyses of groundwater from piezometers located around a reclaimed landfill in Otwock (Poland) were performed in order to trace the origin of dissolved inorganic carbon (DIC) in the groundwater. Due to differences in the isotopic composition of carbon from different sources, an analysis of stable carbon isotopes in the groundwater, together with the Keeling plot approach and a two-component mixing model allow us to evaluate the relative contributions of carbon from these sources in the groundwater. In the natural (background) groundwater, DIC concentrations and the isotopic composition of DIC (δ{sup 13}C{sub DIC}) comes from two sources: decomposition of organic matter and carbonate dissolution within the aquifer sediments, whereas in the leachate-contaminated groundwater, DIC concentrations and δ{sup 13}C{sub DIC} values depend on the degradation of organic matter within the aquifer sediments and biodegradation of organic matter stored in the landfill. From the mixing model, about 4–54% of the DIC pool is derived from organic matter degradation and 96–46% from carbonate dissolution in natural conditions. In the leachate-contaminated groundwater, about 20–53% of the DIC is derived from organic matter degradation of natural origin and 80–47% from biodegradation of organic matter stored in the landfill. Partial pressure of CO{sub 2} (P CO{sub 2}) was generally above the atmospheric, hence atmospheric CO{sub 2} as a source of carbon in DIC pool was negligible in the

  13. Stable isotope analysis of dissolved carbon species of Hot Lake, WA

    Science.gov (United States)

    Courtney, S.; Moran, J.; Cory, A. B.; Lindemann, S. R.; Fredrickson, J.

    2013-12-01

    Hot Lake is a hypersaline, meromictic lake in north-central Washington. The lake is epsomitic, with seasonably-variable salinity (.2 to 2 M magnesium sulfate) and produces carbonates and salt precipitates. The maximum depth of the lake is around 2.5 m, and below a thermocline there is intense solar heat retention in the monolimnion, often exceeding 50°C. Despite these extreme and variable conditions, a microbial mat of up to 1.5 cm thick thrives annually in Hot Lake. The mat is widespread throughout the lake at water depths (during our experiments) ranging from 60cm-140cm. It is comprised of a variety of cyanobacteria along with other autotrophic and heterotrophic bacteria. These populations are visibly stratified with four consistent laminae displaying differences in bacterial pigmentation. Many of the layers contain carbonate species, but the full relationship between the mat and the carbonate crystallization is not known. We are studying the microbial interactions and carbon cycling of the mat communities, using stable isotope analysis of the mat and the lake water, both in situ and ex situ. We are exploring the incorporation and movement of carbon in the mat, spatially and temporally, to understand the fixation mechanisms and metabolic processes at play in this environment. This was done primarily using stable isotope ratio mass spectrometry. The focus of this work is on the study and measurement of dissolved organic and inorganic carbon using a GasBench and IRMS setup, following methods adapted from Lang et al. (2012). To account for the unique chemistry of Hot Lake, trials on the effects of oxidation conditions and salinity were done on lab-synthesized samples to compare to Hot Lake results. The majority of lake water analyses were done in conjunction with a stable isotope probing (SIP) experiment, completed during two 24-hour periods at Hot Lake in June and July of 2013. The SIP experiments included ex situ incubations (in separate glass containers on the

  14. Molecular and stable carbon isotopic compositions of hopanoids in seep carbonates from the South China Sea continental slope

    Science.gov (United States)

    Guan, Hongxiang; Sun, Yongge; Mao, Shengyi; Zhu, Xiaowei; Wu, Nengyou

    2014-10-01

    The lipid biomarkers of hopanoids in cold seep carbonates from the South China Sea continental slope were investigated by gas chromatography-mass spectrometer (GC-MS) and gas chromatography-isotope ratio-mass spectrometer (GC-ir-MS). The distribution of hopanes/hopenes shows a preference for the ‘biological’ 17β(H), 21β(H)-over the ‘geological’ 17α(H), 21β(H)-configuration. This interpretation is in agreement with the strong odd-even preference of long-chain n-alkanes in those samples, suggesting that the ββ hopanes may be the early diagenetic products of biohopanoids and the αβ, βα configurations of hopanes were mainly derived from allochthonous sources contributing to the organic matter of the carbonates. In terms of hopanoid acids, the C30 to C33 17β(H), 21β(H)-hopanoid acids were detected with C32 17β(H), 21β(H)-hopanoid acid being the most abundant. However, there is a significant difference in stable carbon isotopic compostions of the C32 17β(H), 21β(H)-hopanoic acid among samples (-30.7‰ to -69.8‰). The δ13C values match well with the carbon isotopic compositions of SRB-derived iso-/anteiso-C15:0 fatty acids in the samples, which strongly depend on the carbon utilization types by microbe. The most abundant compound of hopanols detected in the samples, C30-17β(H), 21β(H)-hopanol, may be a good indicator of diagenetic product of type I methanotrophs. The molecular and carbon isotopic compositions of hopanoids demonstrate clearly that there is a combination contribution of both SRB and type I or type X methanotrophs to the source organism in the seep carbonates from the South China Sea continental slope.

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

    NARCIS (Netherlands)

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

    2015-01-01

    Carbon (d13Corg, d13Ccarb) and oxygen (d18Ocarb) isotope records are presented for an expanded Upper Cretaceous (Turonian–Coniacian) hemipelagic succession cored in the central Bohemian Cretaceous Basin, Czech Republic. Geophysical logs, biostratigraphy and stable carbon isotope chemostratigraphy pr

  16. Partitioning water and carbon fluxes in a Mediterranean oak woodland using stable oxygen isotopes

    Science.gov (United States)

    Dubbert, Maren; Piayda, Arndt; Cuntz, Matthias; Correia, Alexandra; Silva, Filipe Costa e.; Pereira, Joao; Werner, Christiane

    2014-05-01

    Water is a key factor driving ecosystem productivity, especially in water-limited ecosystems. A separation of the component fluxes is needed to gain a functional understanding on the development of net ecosystem water fluxes and their coupling with biogeochemical cycles. Oxygen isotope signatures are valuable tracers for water movements within the ecosystem because of the distinct isotopic compositions of water in soil and vegetation. In the past, determination of isotopic signatures of evaporative or transpirational fluxes has been challenging since measurements of water vapor isotopes were difficult to obtain using cold-trap methods, delivering data with low time resolution. Recent developments in laser spectroscopy now enable direct high frequency measurements of the isotopic composition of atmospheric water vapor (δv), evapotranspiration (δET), and its components and allow validations of common modeling approaches for estimating δE and δT based on Craig and Gordon (1965). Here, a novel approach was used, combining a custom build flow-through gas-exchange branch chamber with a Cavity Ring-Down Spectrometer in a Mediteranean cork-oak woodland where two vegetation layers respond differently to drought: oak-trees (Quercus suber L.) avoid drought due to their access to ground water while herbaceous plants survive the summer as seeds. We aimed at 1) testing the Craig and Gordon equation for soil evaporation against directly measured δE and 2) quantifying the role of non-steady-state transpiration under natural conditions. Thirdly, we used this approach to quantify the impact of the understory herbaceous vegetation on ecosystem carbon and water fluxes throughout the year and disentangle how ET components of the ecosystem relate to carbon dioxide exchange. We present one year data comparing modeled and measured stable oxygen isotope signatures (δ18O) of soil evaporation, confirming that the Craig and Gordon equation leads to good agreement with measured δ18O of

  17. Carbon allocation belowground in Pinus pinaster using stable carbon isotope pulse labeling technique

    Science.gov (United States)

    Dannoura, M.; Bosc, A.; Chipeaux, C.; Sartore, M.; Lambrot, C.; Trichet, P.; Bakker, M.; Loustau, D.; Epron, D.

    2010-12-01

    Carbon allocation belowground competes with aboveground growth and biomass production. In the other hand, it contributes to resource acquisition such as nutrient, water and carbon sequestration in soil. Thus, a better characterization of carbon flow from plant to soil and its residence time within each compartment is an important issue for understanding and modeling forest ecosystem carbon budget. 13C pulse labeling of whole crown was conducted at 4 seasons to study the fate of assimilated carbon by photosynthesis into the root on 12 year old Pinus pinaster planted in the INRA domain of Pierroton. Maritime pine is the most widely planted species in South-West Europe. Stem, root and soil CO2 effluxes and their isotope composition were measured continuously by tunable diode laser absorption spectroscopy with a trace gas analyzer (TGA 100A; Campbell Scientific) coupled to flow-through chambers. 13CO2 recovery and peak were observed in respiration of each compartment after labeling. It appeared sequentially from top of stem to bottom, and to coarse root. The maximum velocity of carbon transfer was calculated as the difference in time lag of recovery between two positions on the trunk or on the root. It ranged between 0.08-0.2 m h-1 in stem and between 0.04-0.12 m h-1 in coarse root. This velocity was higher in warmer season, and the difference between time lag of recovery and peak increased after first frost. Photosynthates arrived underground 1.5 to 5 days after labeling, at similar time in soil CO2 effluxes and coarse root respiration. 0.08-1.4 g of carbon was respired per tree during first 20 days following labeling. It presented 0.6 -10% of 13C used for labeling and it is strongly related to seasons. The isotope signal was detected in fine root organs and microbial biomass by periodical core sampling. The peak was observed 6 days after labeling in early summer while it was delayed more than 10 days in autumn and winter with less amount of carbon allocated

  18. Inorganic markers, carbonaceous components and stable carbon isotope from biomass burning aerosols in northeast China

    Science.gov (United States)

    Cao, F.; Zhang, Y.; Kawamura, K.

    2015-12-01

    To better characterize the sources of fine particulate matter (i.e. PM2.5) in Sanjiang Plain, Northeast China, aerosol chemical composition such total carbon (TC), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and inorganic ions were studied as well as stable carbon isotopic composition (δ13C) of TC. Intensively open biomass burning episodes were identified from late September to early October by satellite fire and aerosol optical depth maps. During the biomass burning episodes, concentrations of PM2.5, OC, EC, and WSOC increased by a factor of 4-12 compared to non-biomass-burning periods. Non-sea-salt potassium is strongly correlated with PM2.5, OC, EC and WSOC, suggesting an important contribution of biomass burning emission. The enrichment in both the non-sea-salt potassium and chlorine is significantly larger than other inorganic species, indicating that biomass burning aerosols in Sanjiang Plain is mostly fresh and less aged. In addition, WSOC to OC ratio is relatively lower compared to that reported in biomass burning aerosols in tropical regions, supporting that biomass burning aerosols in Sanjiang Plain is mostly primary and secondary organic aerosols is not significant. A lower average δ13C value (-26.2‰) is found for the biomass-burning aerosols, suggesting a dominant contribution from combustion of C3 plants in the studied region.

  19. Open tube combustion method of organic samples for stable carbon isotope analysis.

    Science.gov (United States)

    Velivetskaya, Tatiana A; Ignatyev, Alexander V; Reize, Marina V; Kiyashko, Serguei I

    2007-01-01

    A simple and effective method for the conversion of organic carbon into carbon dioxide for analysis of stable carbon isotopes (delta(13)C) in samples of various organic substances, soils, sedimentary rocks, oils and volatile organic liquids is presented. The conversion of organic carbon of the samples is carried out in a quartz reactor connected to a vacuum line for CO(2) freezing and purification. A solid organic sample mixed with CuO is placed at the reactor bottom and the reactor is subsequently filled with granular CuO. One end of the CuO column is preheated to 850 degrees C while the other end of the column in contact with the sample is kept at ambient temperature. Heating of the sample (850 degrees C) and the remainder of the column is then performed. The preheated part of the column provides efficient conversion of carbon into CO(2). The reactor for the conversion of volatile liquid organic compounds is filled with granular CuO. The column of CuO is heated to 850 degrees C. Samples of volatile liquids are introduced into the reactor through a septum using a microsyringe. Complete conversion takes 10 min for solid samples and 3 min for volatile liquids. The precision of the delta(13)C analysis for solid and volatile liquid organic substances is +/-0.1 per thousand and +/-0.04 per thousand, respectively.

  20. Vegetational ecotype of the Gyirong Basin in Tibet, China and its response in stable carbon isotopes of mammaltooth enamel

    Institute of Scientific and Technical Information of China (English)

    DENG Tao; LI Yumei

    2005-01-01

    Carbon isotope analysis of modern herbaceous plants in the Gyirong Basin (Tibet, China) indicates that although C3 plants are dominant, C4 plants rarely comprise of the vegetation in the area at 4000 m above sea level. The C4 plants discovered in the Gyirong Basin are Salsola nepalensis of Chenopodiaceae and Pennisetum flaccidum of Gramineae, affirming that C4 plants affected by high solar gain can be distributed at high altitude, which supports the opinion that some C4 plants can exist in areas of high elevation. Carbon isotope analysis of herbivore tooth enamel from the Gyirong Basin indicates that carbon isotopes of structural carbonate in biogenic apatite at high altitude still keep a stable enrichment relationship with those of plants in their diet. Carbon isotopes in tooth enamel are therefore an accurate proxy for vegetation ecotypes and should reflect climatic and environmental features.

  1. Preliminary Study: Application of Off-Axis ICOS to Determine Stable Carbon Isotope in Dissolved Inorganic Carbon

    Science.gov (United States)

    Kim, Y. T.; Lee, J. M.; Hwang, J. H.; Piao, J.; Woo, N. C.

    2015-12-01

    CO2 is one of the major causes for global climate change. Because stable carbon isotope ratio is used to trace carbon source, several analytical techniques likes IRMS (Isotope Ratio Mass Spectrometry) and LAS (Laser Absorption Spectrometry) were extensively used. Off-axis ICOS, a kind of LAS, has merits on long-term stability and field application, therefore it is widely being used in CCS (Carbon Capture and Storage) field. The aim of this study is to extend the application scope of OA-ICOS to determine dissolved inorganic carbon (DIC). Because OA-ICOS showed dependence of δ13C on CO2 concentration, data processing is required. We tested CO2 Carbon Isotope Analyzer (CCIA-36-EP, Los Gatos Research) with both reference gas (δ13C= -28.28‰) and aqueous solutions prepared by dissolving sodium bicarbonate standards (δ13C= -12.26‰ and +3.96‰). The differences of δ13C between reference and measurement values are plotted by CO2 concentrations, then compared. At first, we checked the similarity between our curve pattern for reference gas and Guillon's research (δ13C= -43.99‰) by other Analyzer. To analyze aqueous samples, more errors can be caused than gas analysis. The carbon isotope fractionation occurs during dissolving standard reagents and extracting DIC as CO2 gas form. This effect is mixed with CO2 concentration dependence effect, therefore the curve patterns are different with that for reference gas. Our experiments are done for various δ13C values. It could be an important point to use OA-ICOS to analyze DIC, too.

  2. Stable carbon and oxygen isotope record of central Lake Erie sediments

    Science.gov (United States)

    Tevesz, M.J.S.; Spongberg, A.L.; Fuller, J.A.

    1998-01-01

    Stable carbon and oxygen isotope data from mollusc aragonite extracted from sediment cores provide new information on the origin and history of sedimentation in the southwestern area of the central basin of Lake Erie. Sediments infilling the Sandusky subbasin consist of three lithologic units overlying glacial deposits. The lowest of these is a soft gray mud overlain by a shell hash layer containing Sphaerium striatinum fragments. A fluid mud unit caps the shell hash layer and extends upwards to the sediment-water interface. New stable isotope data suggest that the soft gray mud unit is of postglacial, rather than proglacial, origin. These data also suggest that the shell hash layer was derived from erosional winnowing of the underlying soft gray mud layer. This winnowing event may have occurred as a result of the Nipissing flood. The Pelee-Lorain moraine, which forms the eastern boundary of the Sandusky subbasin, is an elevated area of till capped by a sand deposit that originated as a beach. The presence of both the shell hash layer and relict beach deposit strengthens the interpretation that the Nipissing flood was a critical event in the development of the southwestern area of the central basin of Lake Erie. This event, which returned drainage from the upper lakes to the Lake Erie basin, was a dominant influence on regional stratigraphy, bathymetry, and depositional setting.

  3. Bulk carbon, oxygen, and hydrogen stable isotope composition of recent resins from amber-producing Hymenaea.

    Science.gov (United States)

    Nissenbaum, Arie; Yakir, Dan; Langenheim, Jean H

    2005-01-01

    Resins of Hymenaea, an angiosperm tree genus known to be a copious resin producer and a major source of amber since the Oligo-Miocene, were collected from a wide range of tropical environments from Latin America and Africa, and analyzed for their carbon, hydrogen, and oxygen stable isotope composition. The average value for delta13C in the resins was found to be -27.0+/-1.3 per thousand, which is very similar to the values reported for resins in other studies. Delta18O values for the Hymenaea resins averaged +11.2+/-1.6 per thousand, or about 20 per thousand more depleted than normal plant cellulose. DeltaD values of the resins ranged from -196 to -319 per thousand, with an average of -243+/-30 per thousand. Rough estimates suggest a fractionation of -200 to -210 per thousand between the resins and the environmental water. This value is similar to the -200 per thousand value observed for the fractionation between other plant lipids and environmental water. The present study suggests that the stable isotope composition of fossil resins (amber) has the potential to provide information on ancient environmental waters.

  4. Stable isotope composition of dissolved inorganic carbon and particulate organic carbon in sea ice from the Ross Sea, Antarctica

    Science.gov (United States)

    Munro, David R.; Dunbar, Robert B.; Mucciarone, David A.; Arrigo, Kevin R.; Long, Matthew C.

    2010-09-01

    We examined controls on the carbon isotopic composition of sea ice brines and organic matter during cruises to the Ross Sea, Antarctica in November/December 1998 and November/December 2006. Brine samples were analyzed for salinity, nutrients, total dissolved inorganic carbon (ΣCO2), and the 13C/12C ratio of ΣCO2 ? Particulate organic matter from sea ice cores was analyzed for percent particulate organic carbon (POC), percent total particulate nitrogen (TPN), and stable carbon isotopic composition (δ13CPOC). ΣCO2 in sea ice brines ranged from 1368 to 7149 μmol kg-1, equivalent to 1483 to 2519 μmol kg-1 when normalized to 34.5 psu salinity (sΣCO2), the average salinity of Ross Sea surface waters. Sea ice primary producers removed up to 34% of the available ΣCO2, an amount much higher than the maximum removal observed in sea ice free water. Carbonate precipitation and CO2 degassing may reduce sΣCO2 by a similar amount (e.g., 30%) in the most hypersaline sea ice environments, although brine volumes are low in very cold ice that supports these brines. Brine ? ranged from -2.6 to +8.0‰ while δ13CPOC ranged from -30.5 to -9.2‰. Isotopic enrichment of the ΣCO2 pool via net community production accounts for some but not all carbon isotopic enrichment of sea ice POC. Comparisons of sΣCO2, ? and δ13CPOC within sea ice suggest that ɛp (the net photosynthetic fractionation factor) for sea ice algae is ˜8‰ smaller than the ɛp observed for phytoplankton in open water regions of the Ross Sea. These results have implications for modeling of carbon uptake and transformation in the ice-covered ocean and for reconstruction of past sea ice extent based on stable isotopic composition of organic matter in sediment cores.

  5. Stable carbon isotope discrimination: an indicator of cumulative salinity and boron stress in Eucalyptus camaldulensis.

    Science.gov (United States)

    Poss, J A; Grattan, S R; Suarez, D L; Grieve, C M

    2000-10-01

    Saplings of Eucalyptus camaldulensis Dehn. Clone 4544, irrigated with water of differing salinities (2 to 28 dS m-1) and boron concentrations (1 to 30 mg l-1), integrated the history of these stresses through the discrimination of stable isotopes of carbon in leaf and woody tissues. Carbon isotope discrimination (delta) was reduced primarily by salinity. Decreases in discrimination in response to boron stress were detected in the absence of salinity stress, but the decreases were significant only in leaf tissues with visible boron injury. Sapwood core samples indicated that salinity- and boron-induced reductions in delta increased with increasing tree age. Absolute values of delta varied with location of leaf or wood tissue, but relative effects of salinity on the relationship between delta and transpiration efficiency (W) were similar. In response to increasing salinity stress, relative decreases in delta paralleled relative decreases in biomass and both indices yielded similar salt tolerance model parameters. The strong correlations between delta, tree fresh weight, leaf area and W suggest that delta is a useful parameter for evaluating salt tolerance of eucalyptus PMID:11269964

  6. Intra-lake stable isotope ratio variation in selected fish species and their possible carbon sources in Lake Kyoga (Uganda): implications for aquatic food web studies

    NARCIS (Netherlands)

    Mbabazi, D.; Makanga, B.; Orach-Meza, F.; Hecky, R.E.; Balirwa, J.S.; Ogutu-Ohwayo, R.; Verburg, P.H.; Chapman, L.; Muhumuza, E.

    2010-01-01

    The stable isotopes of nitrogen (delta 15N) and carbon (delta 13C) provide powerful tools for quantifying trophic relationships and carbon flow to consumers in food webs; however, the isotopic signatures of organisms vary within a lake. Assessment of carbon and nitrogen isotopic signatures in a suit

  7. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-01

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

  8. Analyzing carbon losses from dry soils after precipitation pulses by stable carbon isotopes

    Science.gov (United States)

    Unger, Stephan; Máguas, Cristina; Santos-Pereira, João.; Werner, Christiane

    2010-05-01

    Rain events after drought periods strongly increase soil respiration (Birch effect) and affect plant activity, and thus, may influence the isotopic signal of ecosystem respiration. These CO2-pulses may largely affect the C-balance of arid and semi-arid systems. Here, we evaluate the origins of the Birch effect in a Mediterranean forest and its influence on the isotopic signal of ecosystem (δ13CR) and soil respiration (δ13CSoil). We conducted artificial rain pulses in May and August 2005 and estimated δ13CSoil on intact vegetation, bare and root-free soil in response to watering. After watering in May δ13CSoil showed strong enrichment (-18) and a rapid return to initial values (-27). This transient enrichment was smaller in August than in May (ca. -22). Further, we compared δ13CR and δ13CSoil after first natural rains in October 2005, where both revealed a good relationship over the diurnal and the fortnight cycle. We hypothesize that the 'Birch effect' immediately after irrigation is the result of a hypo-osmotic stress response of the soil microbial community: during sudden moisture changes enriched osmoregulants are rapidly released and mineralized by the soil microbes to avoid cell lysis. After the pulse soil respiration followed a common moisture response. The overall impact of the Birch effect on C-sequestration will depend on both timing and frequency of the rains and thus, on whether the respired CO2 source is microbial or soil organic matter carbon.

  9. Climatic significance of stable carbon isotope in tree rings of Abies spectabibis in southeastern Tibet

    Institute of Scientific and Technical Information of China (English)

    LIU Xiaohong; Qin Dahe; SHAO Xuemei; CHEN Tuo; REN Jiawen

    2003-01-01

    The annually cross-dated stable carbon isotope of tree-ring α-cellulose of Abies spectabibis collected from the southeastern Tibetan Plateau is used to examine its relationship with climatic parameters. The residual △13C series in treerings is constructed after removing the effects of age trend and rising CO2. We found a close relationship between △13C in tree rings and the relative humidity of September-November of the previous year measured at the nearby Nyingchi Meteorological Station, albeit a strong "lagged effect". Thus we developed a transfer function to reconstruct the autumn relative humidity for the Nyingchi region, which explained 37.9% of the total variance (p < 0.001). Our results suggest a high frequency and moderate amplitude variance of the relative humidity before 1800, and the variance reversed afterwards.

  10. Stable carbon isotope fractionation in pollen of Atlas cedar: first steps towards a new palaeoecological proxy for Northwest Africa

    Science.gov (United States)

    Bell, Benjamin; Fletcher, William; Ryan, Peter; Grant, Helen; Ilmen, Rachid

    2016-04-01

    Analysis of stable carbon isotopes can provide information on climate and the environmental conditions at different growth stages of the plant, both past and present. Carbon isotope discrimination in plant tissue is already well understood, and can be used as a drought stress indicator for semi-arid regions. Stable carbon isotope ratios measured directly on pollen provides the potential for the development of long-term environmental proxies (spanning thousands of years), as pollen is well preserved in the environment. Atlas Cedar (Cedrus atlantica Endl. Manetti ex Carrière), is an ideal test case to develop a pollen stable carbon isotope proxy. The tree grows across a wide altitudinal and climatic range and is extremely sensitive to moisture availability. The pollen is abundant, and easily identifiable to the species level in pollen analysis because different cedar species are geographically confined to different regions of the world. In 2015 we sampled 76 individual cedar trees across latitudinal, altitudinal and environmental gradients, highly focused on the Middle Atlas region of Morocco, with 25 additional samples from botanical gardens across Europe and the US to extend these gradients. Here, we report new stable carbon isotope data from pollen, leaf and stem wood from these samples with a view to assessing and quantifying species-specific fractionation effects associated with pollen production. The isotopic response of individual trees at local and wider geographical scales to altitude and climatic conditions is presented. This research forms part of an ongoing PhD project working to develop and calibrate a modern carbon isotope proxy in Atlas cedar pollen, which can ultimately be applied to fossil sequences and complement existing multi-proxy records (e.g. pollen analysis in lake sediments, tree-rings).

  11. Stable isotope composition of bulk and secondary carbonates from the Quaternary loess-paleosol sequence in Sutto, Hungary

    DEFF Research Database (Denmark)

    Koeniger, Paul; Barta, Gabriella; Thiel, Christine;

    2014-01-01

    , and microscale secondary (authigenic) carbonates (calcified root cells, carbonate coatings, hypocoatings, and earthworm biospheroids) and concretions at 10 cm resolution were analysed to interpret stable isotope variations. Isotope values of bulk samples were in the range of 2.6 parts per thousand to -13.9 parts......, secondary carbonates showed more depleted values than bulk samples. Calcified root cells have the most depleted isotope composition with mean values of -16.0 parts per thousand and -11.8 parts per thousand for delta C-13 and 8180, respectively. Results indicate that loess and paleosol secondary carbonates...... or vegetation. Secondary carbonates are more reliable than bulk samples because of their direct connection to the host strata. (C) 2012 Elsevier Ltd and INQUA. All rights reserved....

  12. 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.

  13. 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.

  14. Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of amino sugars in marine sediment

    Directory of Open Access Journals (Sweden)

    R. Zhu

    2014-01-01

    Full Text Available Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e. equivalent to ~ 8 ng of amino sugar carbon. Our results obtained from δ13C analysis of amino sugars in selected marine sediment samples showed that muramic acid had isotopic imprints from indigenous bacterial activities, whereas glucosamine and galactosamine were mainly derived from organic detritus. The analysis of stable carbon isotopic compositions of amino sugars opens a promising window for the investigation of microbial metabolisms in marine sediments and the deep marine biosphere.

  15. Stable carbon isotope characteristics of different plant species and surface soil in arid regions

    Institute of Scientific and Technical Information of China (English)

    Jianying MA; Wei SUN; Huiwen ZHANG; Dunsheng XIA; Chengbang AN; Fahu CHEN

    2009-01-01

    The stable carbon isotope composition in surface soil organic matter (δ13Csoil) contains integrative information on the carbon isotope composition of the standing terrestrial plants (δ13Cleaf). In order to obtain valuable vegetation information from the δ13C of terrestrial sediment, it is necessary to understand the relationship between the δ13C value in modem surface soil and the standing vegetation. In this paper, we studied the δ13C value in modem surface soil organic matter and standing vegetation in arid areas in China, Australia and the United States. The isotopic discrepancy between δ13Csoil andδ13Cleaf of the standing dominant vegetation was examined in those different arid regions. The results show that the δ13Csoil values were consistently enriched compared to the δ13Cleaf. The δ13Cleaf values were positively correlated with δ13Csoil, which suggests that the interference of microorganisms and hydrophytes on the isotopic composition of surface soil organic matter during soil organic matter formation could be ignored in arid regions. The averaged discrepancy between δ13Csoil and δ13Cleaf is about 1.71%0 in Tamarix L. in the Tarim Basin in China, 1.50 ‰ in Eucalytus near Orange in Australia and 1.22 ‰ in Artemisia in Saratoga in the United States, which are different from the results of other studies. The results indicate that the discrepancies in the δ13C value between surface soil organic matter and standing vegetation were highly influenced by the differences in geophysical location and the dominant species of the studied ecosystems. We suggest that caution should be taken when organic matter δ13C in terrestrial sediment is used to extract paleovegetation information (C3/C4 vegetation composition), as the δ13C in soil organic matter is not only determined by the ratio of C3/C4 species, but also profoundly affected by climate change induced variation in the δ13C in dominant species.

  16. Stable isotopes of carbon and nitrogen in suspended matter and sediments from the Godavari estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.; Arya, J.; Subbaiah, Ch.V.; Naidu, S.A.; Gawade, L.; PraveenKumar, P.; Reddy, N.P.C.

    Spatial distribution of the carbon and nitrogen content and their isotopic enrichment in suspended matter and sediments were measured in the Godavari estuary to identify the sources and transformation mechanism of organic matter. Significant...

  17. Comparison of the stable carbon and nitrogen isotopic values of gill and white muscle tissue of fish

    NARCIS (Netherlands)

    Svensson, E.; Freitas, V.; Schouten, S.; Middelburg, J.J.; van der Veer, H.W.; Sinninghe Damsté, J.S.

    2014-01-01

    The potential use of stable carbon and nitrogen isotope ratios (d13C, d15N) of fish gills for studies on fish feeding ecology was evaluated by comparing the d13C and d15N of gill tissue with the more commonly used white muscle tissue. To account for the effect of lipid content on the d13C signatures

  18. Stable isotopes of helium, nitrogen and carbon in a coastal submarine hydrothermal system

    Science.gov (United States)

    Vidal, Francisco V.; Welhan, John; Vidal, Victor M. V.

    1982-03-01

    Geothermal gases from submarine and subaerial hot springs in Ensenada, Baja California Norte, Mexico, were sampled for determination of gas chemistry and helium, nitrogen and stable carbon isotope composition. The submarine hot spring gas is primarily nitrogen (56.1% by volume) and methane (43.5% by volume), whereas nearby subaerial hot spring gases are predominantly nitrogen (95-99% by volume). The N 2/Ar ratios and σ 15N values of the subaerial hot spring gas indicate that it is atmospheric air, depleted in oxygen and enriched in helium. The submarine hot spring gas is most probably derived from marine sediments of Cretaceous age rich in organic matter. CH 4 is a major component of the gas mixture ( σ 13C = -44.05% 0), with only minor amounts of CO 2 ( σ13C= -10.46% 0). The σ 15N of N 2 is + 0.2% 0 with a very high N 2/Ar ratio of 160. The calculated isotopic equilibra tion temperature for CH 4CO 2 carbon exchange at depth in the Punta Banda submarine geothermal field is approximately 200°C in agreement with other geothermometry estimates. The 3He/ 4He ratios of the hot spring gases range from 0.3 to 0.6 times the atmospheric ratio, indicating that helium is predominantly derived from the radioactive decay of U and Th within the continental crust. Thus, not all submarine hydrothermal systems are effective vehicles for mantle degassing of primordial helium.

  19. Trophic Relationships and Habitat Preferences of Delphinids from the Southeastern Brazilian Coast Determined by Carbon and Nitrogen Stable Isotope Composition

    OpenAIRE

    Tatiana Lemos Bisi; Paulo Renato Dorneles; José Lailson-Brito; Gilles Lepoint; Alexandre de Freitas Azevedo; Leonardo Flach,; Olaf Malm; Krishna Das

    2013-01-01

    To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (d13C) and nitrogen (d15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the d13C and d15N values among four populations of S. guianensis. Variation in carbon ...

  20. Annual and seasonal distribution of intertidal foraminifera and stable carbon isotope geochemistry, Bandon Marsh, Oregon, USA

    Science.gov (United States)

    Milker, Yvonne; Horton, Benjamin; Vane, Christopher; Engelhart, Simon; Nelson, Alan R.; Witter, Robert C.; Khan, Nicole S.; Bridgeland, William

    2014-01-01

    We investigated the influence of inter-annual and seasonal differences on the distribution of live and dead foraminifera, and the inter-annual variability of stable carbon isotopes (d13C), total organic carbon (TOC) values and carbon to nitrogen (C/N) ratios in bulk sediments from intertidal environments of Bandon Marsh (Oregon, USA). Living and dead foraminiferal species from 10 stations were analyzed over two successive years in the summer (dry) and fall (wet) seasons. There were insignificant inter-annual and seasonal variations in the distribution of live and dead species. But there was a noticeable decrease in calcareous assemblages (Haynesina sp.) between live populations and dead assemblages, indicating that most of the calcareous tests were dissolved after burial; the agglutinated assemblages were comparable between constituents. The live populations and dead assemblages were dominated by Miliammina fusca in the tidal flat and low marsh, Jadammina macrescens, Trochammina inflata and M. fusca in the high marsh, and Trochamminita irregularis and Balticammina pseudomacrescens in the highest marsh to upland. Geochemical analyses (d13C, TOC and C/N of bulk sedimentary organic matter) show no significant influence of inter-annual variations but a significant correlation of d13C values (R = 20.820, p , 0.001), TOC values (R = 0.849, p , 0.001) and C/N ratios (R = 0.885, p , 0.001) to elevation with respect to the tidal frame. Our results suggest that foraminiferal assemblages and d13C and TOC values, as well as C/N ratios, in Bandon Marsh are useful in reconstructing paleosea-levels on the North American Pacific coast.

  1. Long-term Carbon and Nitrogen Dynamics at SPRUCE Revealed through Stable Isotopes in Peat Profiles

    Science.gov (United States)

    Hobbie, E. A.

    2015-12-01

    Carbon and nitrogen turnover in peatlands is of considerable interest because peat is a large reservoir of stored carbon that could emit greenhouse gases in response to climate change. Because peat cores preserve a long-term record of system carbon and nitrogen dynamics, it is possible to use stable isotopes as markers of changes in carbon (C) and nitrogen (N) dynamics over time. Here, we used δ15N and δ13C patterns throughout the depth profile of peat cores to understand controls over C-N cycling in the Marcell S1 forested bog in northern Minnesota. In multiple regression analyses, δ15N and δ13C correlated strongly with depth, plot location, %C, %N, and each other. Negative correlation of δ15N with %N presumably reflected removal of 15N-depleted N via denitrification, diffusion, or plant N transfer via mycorrhizal fungi. A step increase in the depth coefficient for δ15N of ~3‰ from -25 cm to -35 cm suggested that the N removal process primarily operates at a discrete depth corresponding to the juncture between aerobic and anaerobic layers defined by the water table. Higher δ15N and lower δ13C in plots closer to uplands may reflect distinct hydrology and accompanying shifts in C and N dynamics in the lagg area fringing the bog. The Suess effect (declining δ13CO2 since the Industrial Revoluation) and aerobic decomposition lowered δ13C in recent surficial samples. Small increases in δ13C at -112 cm (4300 calibrated years BP) and -85 cm (3800 calibrated years BP) may reflect C dynamics during a suspected transitional fen stage (based on paleoecology at a nearby bog), when reduced methanotrophy retained less 13C-depleted carbon derived from methane than in later periods. The C/N decreased until about -85 cm and thereafter remained steady, suggesting that the active zone of aerobic processing during drought may extend to this depth. The inflection point in calculated carbon accumulation rates at this depth supports this conclusion.

  2. Forensic Stable Isotope Biogeochemistry

    Science.gov (United States)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  3. Tracing carbon flow through coral reef food webs using a compound-specific stable isotope approach

    KAUST Repository

    McMahon, Kelton

    2015-11-21

    Coral reefs support spectacularly productive and diverse communities in tropical and sub-tropical waters throughout the world’s oceans. Debate continues, however, on the degree to which reef biomass is supported by new water column production, benthic primary production, and recycled detrital carbon (C). We coupled compound-specific stable C isotope ratio (δ13C) analyses with Bayesian mixing models to quantify C flow from primary producers to coral reef fishes across multiple feeding guilds and trophic positions in the Red Sea. Analyses of reef fishes with putative diets composed primarily of zooplankton (Amblyglyphidodon indicus), benthic macroalgae (Stegastes nigricans), reef-associated detritus (Ctenochaetus striatus), and coral tissue (Chaetodon trifascialis) confirmed that δ13C values of essential amino acids from all baseline C sources were both isotopically diagnostic and accurately recorded in consumer tissues. While all four source end-members contributed to the production of coral reef fishes in our study, a single-source end-member often dominated dietary C assimilation of a given species, even for highly mobile, generalist top predators. Microbially reworked detritus was an important secondary C source for most species. Seascape configuration played an important role in structuring resource utilization patterns. For instance, Lutjanus ehrenbergii showed a significant shift from a benthic macroalgal food web on shelf reefs (71 ± 13 % of dietary C) to a phytoplankton-based food web (72 ± 11 %) on oceanic reefs. Our work provides insights into the roles that diverse C sources play in the structure and function of coral reef ecosystems and illustrates a powerful fingerprinting method to develop and test nutritional frameworks for understanding resource utilization.

  4. Studying biosphere-atmosphere exchange of CO2 through Carbon-13 stable isotopes

    NARCIS (Netherlands)

    Velde, van der I.R.

    2015-01-01

    Summary Thesis ‘Studying biosphere-atmosphere exchange of CO2 through carbon-13 stable isotopes’ Ivar van der Velde Making predictions of future climate is difficult, mainly due to large uncertainties in the carbon cycle. The rate at which carbon is stored in the oceans and terrestrial b

  5. Carbon stable isotopes as a palaeoclimate proxy in vascular plant dominated peatlands

    Science.gov (United States)

    Amesbury, M. J.; Charman, D. J.; Newnham, R. M.; Loader, N. J.; Goodrich, J. P.; Royles, J.; Campbell, D. I.; Roland, T. P.; Gallego-Sala, A.

    2015-09-01

    Carbon stable isotope (δ13C) records from vascular plant dominated peatlands have been used as a palaeoclimate proxy, but a better empirical understanding of fractionation processes in these ecosystems is required. Here, we test the potential of δ13C analysis of ombrotrophic restiad peatlands in New Zealand, dominated by the wire rush (Empodisma spp.), to provide a methodology for developing palaeoclimatic records. We took surface plant samples alongside measurements of water table depth and (micro)climate over spatial (six sites spanning > 10° latitude) and temporal (monthly measurements over 1 year) gradients and analysed the relationships between cellulose δ13C values and environmental parameters. We found strong, significant negative correlations between δ13C and temperature, photosynthetically active radiation and growing degree days above 0 °C. No significant relationships were observed between δ13C and precipitation, relative humidity, soil moisture or water table depth, suggesting no growing season water limitation and a decoupling of the expected link between δ13C in vascular plants and hydrological variables. δ13C of Empodisma spp. roots may therefore provide a valuable temperature proxy in a climatically sensitive region, but further physiological and sub-fossil calibration studies are required to fully understand the observed signal.

  6. Using Stable Isotopes of Carbon and Nitrogen to Evaluate Trophic Interactions in Aquatic Environments

    Science.gov (United States)

    Christensen, David R.; LaRoche, Andrew

    2012-01-01

    This paper describes a series of laboratory exercises for upper level biology courses, independent research and/or honors programs. Students sampled fish from a local water body with the assistance of a local fish and wildlife agency. Tissue samples from collected fish were utilized to obtain estimates of the stable isotopes delta[superscript 13]C…

  7. Carbon and nitrogen stable isotopes in suspended matter and sediments from the Schelde Estuary

    NARCIS (Netherlands)

    Middelburg, J.J.; Nieuwenhuize, J.

    1998-01-01

    The C/N and stable C and N isotope ratios (delta(13)C, delta(15)N) of sedimentary and suspended particulate matter were determined in the Schelde Estuary. Suspended matter was divided into 2 to 5 size fractions by centrifugation. Four major pools of organic matter were recognized: riverine, estuarin

  8. Using Phospholipids and Stable Carbon Isotopes to Assess Microbial Community Structures and Carbon Cycle Pathways in Kamchatka Hot Springs

    Science.gov (United States)

    Zhao, W.; Romanek, C. S.; Burgess, E. A.; Wiegel, J.; Mills, G.; Zhang, C. L.

    2006-12-01

    Phospholipid fatty acid (PLFA) and stable carbon isotopes were used to assess the microbial community structures in Kamchatka hot springs. Eighteen mats or surface sediments were collected from hot springs having temperatures of 31 to 91°C and pHs of 4.9 to 8.5. These samples were clearly separated into three groups according to the bacterial PLFA: 1) those dominated by terminally branched odd-numbered fatty acids, 2) those dominated by C18:1 and 3) those dominated by C20:1. With support from other minor PLFA components, group 2 may be used as biomarkers for Chloroflexales or other phototrophic bacteria and group 3 for Aquificales, respectively. Among the sampled hot springs, the Arkashin pool represents the simplest microbial structure with members of Aquificales being the dominant primary producers. On the other hand, the Zavarzin pool may represent the most heterogeneous pool that may include members of Chloroflexales and Aquificales as primary producers. Bacterial 16S rDNA clone libraries confirmed the presence of these microbial groups in the two pools. Results of stable carbon isotope fractionation between CO2 source, bulk biomass and total PLFA showed that primary producers in the Arkashin pool primarily used the reductive tricarboxylic acid (rTCA) cycle (e.g., members of Aquificales); whereas the Zavarzin pool may be a mixture of the 3-hydroxypropionate (3-HP) pathway (e.g. members of Chloroflexales) and the rTCA cycle. Bacterial contribution using the Calvin cycle was not significant and may be less important in Kamchatka hot springs.

  9. Long-range transport of continentally-derived particulate carbon in the marine atmosphere: evidence from stable carbon isotope studies

    OpenAIRE

    Cachier, Héléne; BUAT-MÉNARD, PATRICK; Fontugne, Michel; Chesselet, Roger

    2011-01-01

    Since 1979, we have investigated marine and non-marine sources of particulate carbon in the marine atmosphere from measurements of carbon concentration and isotopic composition 13C/12C). Aerosol samples were collected, mostly during the Sea/Air Exchange (SEAREX) Program experiments, in the northern and southern hemispheres (Sargasso Sea, Enewetak Atoll, Peru upwelling, American Samoa, New Zealand, Amsterdam Island). The concentration and the isotopic composition of particulate carbon of marin...

  10. Dynamics of carbon in deep soils inferred from carbon stable isotopes signatures : a worldwide meta-analysis

    Science.gov (United States)

    Balesdent, Jérôme; Basile-Doelsch, Isabelle; Chadoeuf, Joël; Cornu, Sophie; Derrien, Delphine; Fekiacova, Zuzana; Hatté, Christine

    2014-05-01

    The contribution of soil carbon deeper than 30 cm to the atmospheric carbon balance is still poorly understood. A very straightforward quantification of the gross exchange of carbon between the atmosphere and soil organic matter can be obtained at places where the 13C/12C signature of vegetation has been changed for known durations, due to switch of the photosynthetic metabolism (C3 or C4) or to Free Air Carbon Enrichment experiments. We compiled C and 13C profile data of 113 sites of this type, either gahered from the literature or from our own measurements. Each site comprised two profiles : one where the 13C/12C of the vegetation had been changed, and a reference profile with unchanged vegetation 13C/12C. An isotope mixing equation was used, which takes into account the natural isotope enrichments with depth and decay. Three main variables were calculated at any depth from 0 to 100 cm and in a few sites down to 200 cm : the carbon content, the proportion of new carbon (aged less than the duration of change t) and the amount of new carbon. The database concerned 23 countries, various climates (58% intertropical and 42% between 23° to 56° latitude) and various soil types and textures. Landuses and vegetation consisted in 26% of forests and woodlands, 35% of grasslands and 38% of cropped systems. The duration of the natural labelling t ranged from 2 years to ca. 4000 years. Peatlands, boreal, and desert environments were absent from the database. Non-linear regressions with time across the dataset yielded kinetic parameters of the age distribution on one hand and of the flux of new carbon incorporation (kg C m-2 yr-1) on the other, each calculated by 10 cm depth increments. On the average, the median ages of carbon increase from ca. 15 years at 0 cm to more than 1000 years at 100 cm. Turnover is on the average 2 to 3 times slower for the subsoil (30-100 cm) than for the topsoil (0-30 cm). Based on the incorporation of new C in the first decades, the carbon input

  11. Molecular isotopic engineering (MIE): industrial manufacture of naproxen of predetermined stable carbon-isotopic compositions for authenticity and security protection and intellectual property considerations

    Science.gov (United States)

    Jasper, J. P.; Farina, P.; Pearson, A.; Mezes, P. S.; Sabatelli, A. D.

    2016-05-01

    Molecular Isotopic Engineering (MIE) is the directed stable-isotopic synthesis of chemical products for reasons of product identification and of product security, and also for intellectual property considerations. We report here a generally excellent correspondence between the observed and predicted stable carbon-isotopic (δ13C) results for a successful directed synthesis of racemic mixture from its immediate precursors. The observed results are readily explained by the laws of mass balance and isotope mass balance. Oxygen- and hydrogen isotopic results which require an additional assessment of the effects of O and H exchange, presumably due to interaction with water in the reaction solution, are addressed elsewhere. A previous, cooperative study with the US FDA-DPA showed that individual manufacturers of naproxen could readily be differentiated by their stable-isotopic provenance (δ13C, δ18O, and δD ref. 1). We suggest that MIE can be readily employed in the bio/pharmaceutical industry without alteration of present manufacturing processes other than isotopically selecting and/or monitoring reactants and products.

  12. Stable Carbon Isotopic Compositions of Methylated-MTTC in Crude Oils from Saline Lacustrine Depositional Environment: Source Implications

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Significantly high abundant methyl-MethylTrimethylTridecylChromans (MTTCs) have been detected in aromatic hydrocarbon fractions in crude oils from the Jizhong Depression and Jianghan Basin. The distribution of these compounds is dominated by methyl-MTTC and dimethylMTTC series, which indicate diagenetic products of a hypersaline depositional environment in the early stage and show a low degree of methylation. The occurrence of significantly high abundant methyl-MTTC depends mainly on good preservation conditions with a strongly reductive, hypersaline and water-columned depositional environment and subsequent non-intensive diagenetic transformations. The stable carbon isotopic compositions of the methyl-MTTCs and dimethyl-MTTCs in two samples are far different from the stable carbon isotopic composition of C30 hopane of apparent bacteria biogenesis (up to 4.11‰ and 5.75‰, respectively). This obviously demonstrates that the methyl-MTTC and dimethyl-MTTCs cannot be of bacteria origin, which is different from the previous point of view about non-photosynthetic bacteria products or possible bacteria-reworked products. On the contrary, the stable carbon isotopic compositions of methyi-MTTC and dimethyl-MTTCs in the two samples were similar to that of the samecarbon-numbered n-alkanes (nC27-nC28-nC29), which indicates that they share the same source origin. Especially in the crude oil from the Zhao61 well, stable carbon isotopic compositions are also similar to that of the same carbon-numbered steranes with ααα-20R isomer (mostly less than 0.4‰). In consideration of the results of previous studies on saline lake ecological sedimentation, the authors hold that the methyl-MTTC and dimethyl-MTTCs in the saline lake sediments should be of algal biogenesis origin.

  13. Influence of organic carbon sources and isotope exchange processes between water and nitrate on the fractionation of the stable isotopes 15N/14N and 18O/16O in dissolved nitrate during microbial dentrification in groundwater

    International Nuclear Information System (INIS)

    Stable isotopes of nitrate are commonly used to determine sources and degradation of nitrate. In this study, nitrite oxidizing bacteria were found to promote an oxygen isotope exchange between water and nitrate under anoxic conditions. Also, different carbon sources were found to influence the enrichment of stable isotopes in nitrate during microbial denitrification. Both results refine the stable isotope model of nitrate in respect to nitrate source determination and microbial nitrate reduction.

  14. Can stable isotope fractionation in diatom and coccolith biominerals elucidate the significance of carbon concentrating mechanisms (CCMs) in the past?

    Science.gov (United States)

    Stoll, H.; Bolton, C.; Isensee, K.; Mendez-Vicente, A.; Rubio-Ramos, M.; Mejia-Ramirez, L. M.

    2012-04-01

    Carbon isotopic fractionation in fossil algal biomarkers is typically interpreted to reflect atmospheric CO2 changes assuming simple diffusive uptake of CO2 by cells, however modern algae employ a diverse array of additional strategies to concentrate DIC inside the cell (CCMs). We previously hypothesized that the size-correlated range of vital effects in carbonate liths produced by different coccolithophore species was due to variable significance of CCMs in their C acquisition, and that an absence of interspecific vital effects may reflect a reduced importance of CCMs (or more similar CCMs employed). Here, we present stable isotope data from size-separated deep-sea sediments dominated by small, intermediate and large coccoliths from time slices throughout the Cenozoic. We show that the range of coccolith vital effects is distinct during several major Cenozoic proxy-inferred climate-CO2 transitions, and where vital effects are significant their magnitude scales with cell size in the same sense as modern culture genera (increasing C and O isotope enrichment with decreasing coccolith size). Our new culture experiments with coccolithophorids reveal strong plasticity in the magnitude of stable carbon isotope vital effects in coccoliths of Calcidiscus leptoporus and Emiliania huxleyi with variable CO2. At high CO2 coccoliths of both species are more isotopically enriched, but the magnitude is greater in C. leptoporus leading to reduced interspecific offsets at high CO2. In the case of E. huxleyi, higher CO2 conditions resulted in significant reduction in the magnitude of DIC accumulation in the intracellular carbon pool, and more positive carbon isotopic values inside the particulate organic matter. A model of carbon acquisition incorporating both photosynthetic and carbonate production is used to explore mechanisms for these relationships. We also investigate fractionation in diatom organic matter and diatom biomineral-bound organic matter. While the carbon isotopic

  15. Mass spectrometric analysis of stable carbon isotopes in abiogenic and biogenic natural compounds

    International Nuclear Information System (INIS)

    This report describes the general methodology of sup/13/ carbon analysis on mass spectrometer and various preparation systems developed for conversion of samples into isotopically non-fractionated and purified carbon dioxide. Laboratory standards required for sup/13/ C analysis have been calibrated against international standards. The reproducibility/accuracy of sample preparation and analysis on mass spectrometer for sup/13/ C or sup/12/ C measurement is well within the internationally acceptable limits. (author)

  16. 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.

  17. Stable isotopes. Applications and production; Les isotopes stables. Applications - production

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, S.; Louvet, P.; Soulie, E. [eds.

    1994-12-31

    This conference presents 46 communications concerning stable isotope production, utilization and application, grouped in 6 sessions and posters. The various themes are: biological applications (pharmacology, medical diagnosis, metabolism and protein studies, toxicity and response studies, labelled compounds), analysis procedures (NMR analysis for macromolecules, tracer studies), nuclear applications (utilization of stable isotopes in nuclear reactors), biological, physical and chemical applications (mass transfer, mobility, crystallography, isotopic exchange), stable isotope production (ion chromatography, ion cyclotron resonance, cryogenic distillation).

  18. [Meta-analysis of stable carbon and nitrogen isotopic enrichment factors for aquatic animals].

    Science.gov (United States)

    Guo, Liang; Sun, Cui-ping; Ren, Wei-zheng; Zhang, Jian; Tang, Jian-iun; Hu, Liana-liang; Chen, Xin

    2016-02-01

    Isotopic enrichment factor (Δ, the difference between the δ value of food and a consumer tissue) is an important parameter in using stable isotope analysis (SIA) to reconstruct diets, characterize trophic relationships, elucidate patterns of resource allocation, and construct food webs. Isotopic enrichment factor has been considered as a constancy value across a broad range of animals. However, recent studies showed that the isotopic enrichment factor differed among various types of animals although the magnitude of variation was not clear. Here, we conducted a meta-analysis to synthesize and compare Δ13C and Δ15N among four types of aquatic animals (teleosts, crustaceans, reptiles and molluscs). We searched for papers published before 2014 on Web of Science and CNKI using the key words "stable isotope or isotopic fractionation or fractionation factor or isotopic enrichment or trophic enrichment". Forty-two publications that contain 140 studies on Δ13C and 159 studies on Δ15N were obtained. We conducted three parallel meta-analyses by using three types of weights (the reciprocal of variance as weights, the sample size as weights, and equal weights). The results showed that no significant difference in Δ13C among different animal types (teleosts 1.0 per thousand, crustaceans 1.3 per thousand, reptiles 0.5 per thousand, and molluscs 1.5 per thousand), while Δ15N values were significantly different (teleosts 2.4 per thousand, crustaceans 3.6 per thousand, reptiles 1.0 per thousand and molluscs 2.5 per thousand). Our results suggested that the overall mean of Δ13C could be used as a general enrichment factor, but Δ15N should be chosen according to the type of aquatic animals in using SIA to analyze trophic relationships, patterns of resource allocation and food webs.

  19. Carbon and nitrogen stable isotope turnover rates and diet-tissue discrimination in Florida manatees (Trichechus manatus latirostris).

    Science.gov (United States)

    Alves-Stanley, Christy D; Worthy, Graham A J

    2009-08-01

    The Florida manatee (Trichechus manatus latirostris) is a herbivorous marine mammal that occupies freshwater, estuarine and marine habitats. Despite being considered endangered, relatively little is known about its feeding ecology. The present study expands on previous work on manatee feeding ecology by providing critical baseline parameters for accurate isotopic data interpretation. Stable carbon and nitrogen isotope ratios were examined over a period of more than 1 year in the epidermis of rescued Florida manatees that were transitioning from a diet of aquatic forage to terrestrial forage (lettuce). The mean half-life for (13)C turnover was 53 and 59 days for skin from manatees rescued from coastal and riverine regions, respectively. The mean half-life for (15)N turnover was 27 and 58 days, respectively. Because of these slow turnover rates, carbon and nitrogen stable isotope analysis in manatee epidermis is useful in summarizing average dietary intake over a long period of time rather than assessing recent diet. In addition to turnover rate, a diet-tissue discrimination value of 2.8 per thousand for (13)C was calculated for long-term captive manatees on a lettuce diet. Determining both turnover rate and diet-tissue discrimination is essential in order to accurately interpret stable isotope data. PMID:19617427

  20. Carbon and nitrogen stable isotope turnover rates and diet-tissue discrimination in Florida manatees (Trichechus manatus latirostris).

    Science.gov (United States)

    Alves-Stanley, Christy D; Worthy, Graham A J

    2009-08-01

    The Florida manatee (Trichechus manatus latirostris) is a herbivorous marine mammal that occupies freshwater, estuarine and marine habitats. Despite being considered endangered, relatively little is known about its feeding ecology. The present study expands on previous work on manatee feeding ecology by providing critical baseline parameters for accurate isotopic data interpretation. Stable carbon and nitrogen isotope ratios were examined over a period of more than 1 year in the epidermis of rescued Florida manatees that were transitioning from a diet of aquatic forage to terrestrial forage (lettuce). The mean half-life for (13)C turnover was 53 and 59 days for skin from manatees rescued from coastal and riverine regions, respectively. The mean half-life for (15)N turnover was 27 and 58 days, respectively. Because of these slow turnover rates, carbon and nitrogen stable isotope analysis in manatee epidermis is useful in summarizing average dietary intake over a long period of time rather than assessing recent diet. In addition to turnover rate, a diet-tissue discrimination value of 2.8 per thousand for (13)C was calculated for long-term captive manatees on a lettuce diet. Determining both turnover rate and diet-tissue discrimination is essential in order to accurately interpret stable isotope data.

  1. 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

  2. Climate Evolution Recorded by Organic Carbon Stable Isotope since 5 kaB. P. in Poyang Lake Area, China

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Based on the data of organic carbon stable isotope ratios and nagnetic susceptibility, climate evolution in the past 5 kaB. P. in Poyang Lake plain (in Jiangxi Province) has been reconstructed. The results of the research indicate that the climate evolution can be divided into nine stages in the past 5kaB. P.. Comparisons of different regional environmental records suggest that the intensity and the temporal-spatial changes of monsoon in China mainly controlled the climate evolution.

  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. 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

  5. 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...

  6. Differentiation of Pigment in Eggs Using Carbon ((13)C/(12)C) and Nitrogen ((15)N/(14)N) Stable Isotopes.

    Science.gov (United States)

    Sun, Feng M; Shi, Guang Y; Wang, Hui W

    2016-07-01

    Consumers prefer natural and healthy food, but artificial pigments are often abused in egg products. The study aimed at differentiating the origin of pigments in eggs by applying the technique of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope analysis. Five hundred sixty laying hens were randomly distributed into 14 treatments, which were divided into four groups: maize, carophyll red pigment, carophyll yellow pigment, and a mixture of carophyll red and yellow pigments. Eggs were collected and pretreated to determe the values of the Roche Yolk Color Fan (RCF), δ(13)C, and δ(15)N. With increasing maize content, the RCF and δ(13)C values of yolks increased. Moreover, the RCF values in the three pigment groups were significantly influenced by the artificial colors, but δ(13)C values were not significantly different, regardless of the existence of pigment. The δ(15)N values in all treatments did not vary as regularly as the carbon stable isotope. A strong positive correlation was found between RCF and δ(13)C in the maize group, but no such correlation was be observed in the pigment groups. It is concluded that carbon stable isotope ratio analysis (δ(13)C) of the yolk can be used to differentiate the origin of the pigment added to eggs.

  7. 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

  8. Differentiation of Pigment in Eggs Using Carbon ((13)C/(12)C) and Nitrogen ((15)N/(14)N) Stable Isotopes.

    Science.gov (United States)

    Sun, Feng M; Shi, Guang Y; Wang, Hui W

    2016-07-01

    Consumers prefer natural and healthy food, but artificial pigments are often abused in egg products. The study aimed at differentiating the origin of pigments in eggs by applying the technique of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope analysis. Five hundred sixty laying hens were randomly distributed into 14 treatments, which were divided into four groups: maize, carophyll red pigment, carophyll yellow pigment, and a mixture of carophyll red and yellow pigments. Eggs were collected and pretreated to determe the values of the Roche Yolk Color Fan (RCF), δ(13)C, and δ(15)N. With increasing maize content, the RCF and δ(13)C values of yolks increased. Moreover, the RCF values in the three pigment groups were significantly influenced by the artificial colors, but δ(13)C values were not significantly different, regardless of the existence of pigment. The δ(15)N values in all treatments did not vary as regularly as the carbon stable isotope. A strong positive correlation was found between RCF and δ(13)C in the maize group, but no such correlation was be observed in the pigment groups. It is concluded that carbon stable isotope ratio analysis (δ(13)C) of the yolk can be used to differentiate the origin of the pigment added to eggs. PMID:27302905

  9. Stable isotope (C, O) and monovalent cation fractionation upon synthesis of carbonate-bearing hydroxyl apatite (CHAP) via calcite transformation

    Science.gov (United States)

    Böttcher, Michael E.; Schmiedinger, Iris; Wacker, Ulrike; Conrad, Anika C.; Grathoff, Georg; Schmidt, Burkhard; Bahlo, Rainer; Gehlken, Peer-L.; Fiebig, Jens

    2016-04-01

    Carbonate-bearing hydroxyl-apatite (CHAP) is of fundamental and applied interest to the (bio)geochemical, paleontological, medical and material science communities, since it forms the basic mineral phase in human and animal teeth and bones. In addition, it is found in non-biogenic phosphate deposits. The stable isotope and foreign element composition of biogenic CHAP is widely used to estimate the formation conditions. This requires careful experimental calibration under well-defined boundary conditions. Within the DFG project EXCALIBOR, synthesis of carbonate-bearing hydroxyapatite was conducted via the transformation of synthetic calcite powder in aqueous solution as a function of time, pH, and temperature using batch-type experiments. The aqueous solution was analyzed for the carbon isotope composition of dissolved inorganic carbonate (gas irmMS), the oxygen isotope composition of water (LCRDS), and the cationic composition. The solid was characterized by powder X-ray diffraction, micro Raman and FTIR spectroscopy, SEM-EDX, elemental analysis (EA, ICP-OES) and gas irmMS. Temperature was found to significantly impact the transformation rate of calcite to CHAP. Upon complete transformation, CHAP was found to contain up to 5% dwt carbonate, depending on the solution composition (e.g., pH), both incorporated on the A and B type position of the crystal lattice. The oxygen isotope fractionation between water and CHAP decreased with increasing temperature with a tentative slope shallower than those reported in the literature for apatite, calcite or aragonite. In addition, the presence of dissolved NH4+, K+ or Na+ in aqueous solution led to partial incorporation into the CHAP lattice. How these distortions of the crystal lattice may impact stable isotope discrimination is subject of future investigations.

  10. Springtime carbon emission episodes at the Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    Science.gov (United States)

    Jung, J.; Kawamura, K.

    2011-11-01

    In order to investigate the emission of carbonaceous aerosols at the Gosan background super-site (33.17° N, 126.10° E) in East Asia, total suspended particles (TSP) were collected during spring of 2007 and 2008 and analyzed for particulate organic carbon, elemental carbon, total carbon (TC), total nitrogen (TN), and stable carbon isotopic composition (δ13C) of TC. The stable carbon isotopic composition of TC (δ13CTC) was found to be lowest during pollen emission episodes (range: -26.2‰ to -23.5‰, avg. -25.2 ± 0.9‰), approaching those of the airborne pollen (-28.0‰) collected at the Gosan site. Based on a carbon isotope mass balance equation, we found that ~42% of TC in the TSP samples during the pollen episodes was attributed to airborne pollen from Japanese cedar trees planted around tangerine farms in Jeju Island. A negative correlation between the citric acid-carbon/TC ratios and δ13CTC was obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollen and then transported to the Gosan site. Thermal evolution patterns of organic carbon during the pollen episodes were characterized by high OC evolution in the OC2 temperature step (450 °C). Since thermal evolution patterns of organic aerosols are highly influenced by their molecular weight, they can be used as additional information on the formation of secondary organic aerosols and the effect of aging of organic aerosols during the long-range atmospheric transport and sources of organic aerosols.

  11. Springtime carbon emission episodes at the Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    Directory of Open Access Journals (Sweden)

    J. Jung

    2011-11-01

    Full Text Available In order to investigate the emission of carbonaceous aerosols at the Gosan background super-site (33.17° N, 126.10° E in East Asia, total suspended particles (TSP were collected during spring of 2007 and 2008 and analyzed for particulate organic carbon, elemental carbon, total carbon (TC, total nitrogen (TN, and stable carbon isotopic composition (δ13C of TC. The stable carbon isotopic composition of TC (δ13CTC was found to be lowest during pollen emission episodes (range: −26.2‰ to −23.5‰, avg. −25.2 ± 0.9‰, approaching those of the airborne pollen (−28.0‰ collected at the Gosan site. Based on a carbon isotope mass balance equation, we found that ~42% of TC in the TSP samples during the pollen episodes was attributed to airborne pollen from Japanese cedar trees planted around tangerine farms in Jeju Island. A negative correlation between the citric acid-carbon/TC ratios and δ13CTC was obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollen and then transported to the Gosan site. Thermal evolution patterns of organic carbon during the pollen episodes were characterized by high OC evolution in the OC2 temperature step (450 °C. Since thermal evolution patterns of organic aerosols are highly influenced by their molecular weight, they can be used as additional information on the formation of secondary organic aerosols and the effect of aging of organic aerosols during the long-range atmospheric transport and sources of organic aerosols.

  12. Multi-decadal carbon and water relations of African tropical humid forests: a tree-ring stable isotope analysis

    Science.gov (United States)

    Hufkens, Koen; Helle, Gerd; Beeckman, Hans; de Haulleville, Thales; Kearsley, Elizabeth; Boeckx, Pascal

    2013-04-01

    Little is known about the temporal dynamics of the carbon sequestering capacity and dynamics of African tropical humid forest ecosystems in response to various environmental drivers. This lack of knowledge is mainly due to the absence of ecosystem scale flux measurements of gas exchange. However, tree growth often displays itself as alternating pattern of visible rings due to the seasonally varying growth speed of the vascular cambium. Consequently, analysis of tree growth through tree-ring analysis provides us with insights into past responses of the carbon sequestering capacity of key species to abrupt ecosystem disturbances and, while slower, a changing climate. Not only does the width and density of growth rings reflect annual growth but their isotopic composition of 13C/12C and 18O/16O isotopes also reveal the environmental conditions in which the trees were growing. In particular, stable isotope ratios in tree-rings of carbon are influenced by fractionation through carboxylation during photosynthesis and changes in leaf stomatal conductance. Similarly, fractionation of oxygen isotopes of soil water occurs at the leaf level through evapo-transipiration. As a consequence, 18O/16O (δ18O) values in wood cores will reflect both the signal of the source water as well as that of for example summer humidity. Therefore, both C and O stable isotopes might not only be valuable as proxy data for past climatic conditions but they also serve as an important tool in understanding carbon and water relations within a tropical forest ecosystems. To this end we correlate long term climate records (1961 - present) with tree ring measurement of incremental growth and high resolution analysis of tree-core stable isotope composition(δ13C , δ18O) at a tropical humid forests in the DR Congo. The Yangambi Man And Biosphere (MAB) reserve is located in the north-eastern part of DR Congo, with a distinct tropical rainforest climate. In addition to the tree-core data records and

  13. Phenotyping hepatocellular metabolism using uniformly labeled carbon-13 molecular probes and LC-HRMS stable isotope tracing.

    Science.gov (United States)

    Meissen, John K; Pirman, David A; Wan, Min; Miller, Emily; Jatkar, Aditi; Miller, Russell; Steenwyk, Rick C; Blatnik, Matthew

    2016-09-01

    Metabolite stable isotope tracing is a powerful bioanalytical strategy that has the potential to unravel phenotypic markers of early pharmaceutical efficacy by monitoring enzymatic incorporation of carbon-13 atoms into targeted pathways over time. The practice of probing biological systems with carbon-13 labeled molecules using broad MS-based screens has been utilized for many years in academic laboratories but has had limited application in the pharmaceutical R&D environment. The goal of this work was to establish a LCMS analytical workflow that was capable of monitoring carbon-13 isotope changes in glycolysis, the TCA and urea cycles, and non-essential amino acid metabolism. This work applies a standardized protein precipitation with 80% cold methanol and two distinct reverse-phase ion-pair liquid chromatography methods coupled to either a positive- or negative-ion mode high-resolution accurate mass spectrometry screening method. The data herein combines thousands of single-point peak integrations into a novel metabolite network map as a visualization aid to probe and monitor stable isotope incorporation in murine hepatocytes using uniformly labeled (13)C6 glucose, (13)C3 lactate, and (13)C5 glutamine. This work also demonstrates that nitrogen metabolism may have a large influence on the TCA cycle and gluconeogenic carbon fluxes in hepatocyte cell culture. PMID:27343766

  14. Stable carbon isotopes of dissolved inorganic carbon for a zonal transect across the subpolar North Atlantic Ocean in summer 2014

    Science.gov (United States)

    Humphreys, Matthew P.; Greatrix, Florence M.; Tynan, Eithne; Achterberg, Eric P.; Griffiths, Alex M.; Fry, Claudia H.; Garley, Rebecca; McDonald, Alison; Boyce, Adrian J.

    2016-06-01

    The stable carbon isotope composition of dissolved inorganic carbon (δ13CDIC) in seawater was measured in samples collected during June-July 2014 in the subpolar North Atlantic. Sample collection was carried out on the RRS James Clark Ross cruise JR302, part of the "Radiatively Active Gases from the North Atlantic Region and Climate Change" (RAGNARoCC) research programme. The observed δ13CDIC values for cruise JR302 fall in a range from -0.07 to +1.95 ‰, relative to the Vienna Pee Dee Belemnite standard. From duplicate samples collected during the cruise, the 1σ precision for the 341 results is 0.08 ‰, which is similar to our previous work and other studies of this kind. We also performed a cross-over analysis using nearby historical δ13CDIC data, which indicated that there were no significant systematic offsets between our measurements and previously published results. We also included seawater reference material (RM) produced by A. G. Dickson (Scripps Institution of Oceanography, USA) in every batch of analysis, enabling us to improve upon the calibration and quality-control procedures from a previous study. The δ13CDIC is consistent within each RM batch, although its value is not certified. We report δ13CDIC values of 1.15 ± 0.03 ‰ and 1.27 ± 0.05 ‰ for batches 141 and 144 respectively. Our JR302 δ13CDIC data can be used - along with measurements of other biogeochemical variables - to constrain the processes that control DIC in the interior ocean, in particular the oceanic uptake of anthropogenic carbon dioxide and the biological carbon pump. Our δ13CDIC results are available from the British Oceanographic Data Centre - doi:10.5285/22235f1a-b7f3-687f-e053-6c86abc0c8a6.

  15. Use of stable carbon isotope analysis to assess natural attenuation of organic contaminants in the unsaturated zone

    International Nuclear Information System (INIS)

    Introduction Natural attenuation is an attractive remediation strategy when dealing with petroleum-hydrocarbon contaminated sites because of its cost efficiency. The unsaturated zone can play an important role in regulating the contaminant transfer between soil and groundwater. On one hand, contaminants from the soil zone may be degraded in the unsaturated zone thus preventing groundwater contamination. On the other hand, contaminants diffusing from the subsurface towards the atmosphere may be eliminated before reaching potential targets. Biodegradation is usually the main process leading to contaminant destruction and is usually considered to be the only process to influence 13C/12C ratio of organic contaminants in the saturated zone. Therefore, carbon and hydrogen isotope analysis has been used as a tool to demonstrate biodegradation (Griebler et al. 2004, Steinbach et al. 2004). Carbon and hydrogen isotope fractionation occurs during biodegradation as a consequence of the slightly faster cleavage of chemical bonds between light isotopes of an element compared to heavy isotopes. The difference in degradation rates leads to an enrichment of the heavy isotopes in the residual contaminant pool compared to the initial value. Most of the field studies focused on the saturated zone (Meckenstock et al. 2004) compare to only few studies on the unsaturated zone (Kirtland et al. 2005, Stehmeier et al. 1999). The aim of this study was to evaluate whether compound-specific stable isotope analysis can be used to demonstrate biodegradation of petroleum hydrocarbons in the unsaturated zone. The study included a field experiment and mathematical simulations. At the field site, a defined mixture of hydrocarbons was buried in a sandy unsaturated zone and the evolution of concentration and isotope ratios of various hydrocarbons was followed using a dense network of sampling points. The study was complemented with two mathematical simulations performed to gain insight into the

  16. Stable carbon and oxygen isotope studies of Late Weichselian lake sediments in southern Sweden and northern Poland, with palaeoclimatic implications

    International Nuclear Information System (INIS)

    Late Weichselian lacustrine sediment sequences from southern Sweden and northern Poland were studied by means of stable isotope analysis in order to reconstruct the climatic development and climatically induced environmental changes in the respective regions. The methods used include analyses of the stable carbon isotope composition (δ13C) of bulk organic material, and the stable carbon and oxygen isotope compositions (δ13C, δ18O) of bulk carbonates and carbonate shells of aquatic organisms. These results were complemented and supported by lithological, chemical and biostratigraphic data (plant macrofossils, insects, molluscs). Chronological data were obtained by AMS radiocarbon dates and correlations based on pollen analysis. At c. 12.400 BP a climatic change from arctic, dry, and continental, to subarctic and more humid and maritime conditions occurred in southern Sweden. The Older Dryas stadial (c.12.200-12.000 BP) is characterized by a temporary return to generally colder , drier, and more continental conditions, followed by generally favourable (subarctic), although unstable, climatic conditions. At c. 11.300 BP a gradual transition towards a colder and more continental climate was initiated, followed by total absence of limnic carbonates during the Younger Dryas stadial (c. 11.000-10.200 BP), indicating arctic and continental conditions. The transition to the Holocene is characterized by a rapid and strong climatic warming. The results from northern Poland point to some important differences compared to this development. A climatic warming around 13.000 BP was followed by generally favourable climatic conditions enabling continuous sedimentation of limnic carbonates during the Late Weichselian. Distinct depletions of 13C in lacustrine organic material at the transition to the Holocene were recorded in southern Sweden, also demonstrated by decreasing mean values obtained from an extensive compilation of δ13C data. A number of processes that may influence

  17. Passage kinetics of concentrates in dairy cows measured with carbon stable isotopes.

    Science.gov (United States)

    Warner, D; Dijkstra, J; Tamminga, S; Pellikaan, W F

    2013-12-01

    Fractional passage rates form a fundamental element within modern feed evaluation systems for ruminants, but knowledge on feed-specific fractional passage is largely lacking. Commonly applied tracer techniques based on externally applied markers, such as chromium-mordanted neutral detergent fibre (Cr-NDF), have been criticised for behaving differently to feed particles. This study describes the use of the carbon stable isotope ratio (13C : 12C) as an internal digesta marker to quantify the fractional passage rate of concentrates through the digestive tract of dairy cows. In a crossover study, five dairy cows were fed low (24.6%) and high (52.6%) levels of concentrates (dry matter (DM) basis) and received a pulse-dosed Cr-NDF and 13C isotopes. The latter was administered orally by exchanging part of the dietary concentrates of low 13C natural abundance with a pulse dose of maize bran-based concentrates of high 13C natural abundance. Fractional passage rates from the rumen (K 1) and from the large intestine (K 2) were determined from faecal marker concentrations of Cr-NDF and of 13C in the DM (13C-DM), NDF (13C-NDF) and neutral detergent soluble (13C-NDS). No differences in K 1 estimates were found for the two concentrate levels fed but significant differences between markers (P<0.001) were observed. Faecal Cr-NDF excretions gave lower K 1 estimates (0.037-0.039/h) than 13C-DM (0.054-0.056/h) and 13C-NDF (0.061-0.063/h). The 13C-NDS was calculated by the difference of 13C in the DM and NDF, and K 1 values (0.039-0.043/h) were comparable to Cr-NDF. Total mean retention time was considerably higher for Cr-NDF (40.9-42.0 h) as compared to 13C-DM and 13C-NDF (32.0-33.5 h; P<0.001). The accuracy of the curve fits for Cr-NDF and 13C-DM and 13C-NDF was overall good (mean prediction error of 9.9-13.9%). Fractional passage rate of Cr-NDF was comparable to studies where this marker was assumed to represent the fractional passage of roughages. However, K 1 estimates based on

  18. Controlling for anthropogenically induced atmospheric variation in stable carbon isotope studies

    Science.gov (United States)

    Long, E.S.; Sweitzer, R.A.; Diefenbach, D.R.; Ben-David, M.

    2005-01-01

    Increased use of stable isotope analysis to examine food-web dynamics, migration, transfer of nutrients, and behavior will likely result in expansion of stable isotope studies investigating human-induced global changes. Recent elevation of atmospheric CO2 concentration, related primarily to fossil fuel combustion, has reduced atmospheric CO2 ??13C (13C/12C), and this change in isotopic baseline has, in turn, reduced plant and animal tissue ??13C of terrestrial and aquatic organisms. Such depletion in CO2 ??13C and its effects on tissue ??13C may introduce bias into ??13C investigations, and if this variation is not controlled, may confound interpretation of results obtained from tissue samples collected over a temporal span. To control for this source of variation, we used a high-precision record of atmospheric CO2 ??13C from ice cores and direct atmospheric measurements to model modern change in CO2 ??13C. From this model, we estimated a correction factor that controls for atmospheric change; this correction reduces bias associated with changes in atmospheric isotopic baseline and facilitates comparison of tissue ??13C collected over multiple years. To exemplify the importance of accounting for atmospheric CO2 ??13C depletion, we applied the correction to a dataset of collagen ??13C obtained from mountain lion (Puma concolor) bone samples collected in California between 1893 and 1995. Before correction, in three of four ecoregions collagen ??13C decreased significantly concurrent with depletion of atmospheric CO2 ??13C (n ??? 32, P ??? 0.01). Application of the correction to collagen ??13C data removed trends from regions demonstrating significant declines, and measurement error associated with the correction did not add substantial variation to adjusted estimates. Controlling for long-term atmospheric variation and correcting tissue samples for changes in isotopic baseline facilitate analysis of samples that span a large temporal range. ?? Springer-Verlag 2005.

  19. A stable isotope study of the hydrological and carbon cycle in meromictic lake, Lovojärvi

    OpenAIRE

    Mutyaba, Colline

    2012-01-01

    Lake Lovojärvi, at its deepest point of 17.5 m, is permanently stratified forming two water layers. The mixolimnion (the upper layer, from 0 to 10 m depth) is affected by seasonal changes while the monimolimnion (bottom layer, from 10 to 17.5 m depth) does not mix and is not affected by seasonal changes. As a result, the lake stores large quantities of dissolved inorganic carbon and methane. I used a multiple stable isotope approach to gain insight into the carbon cycle and water balance of L...

  20. Stable carbon isotope fractionation in the search for life on early Mars

    Science.gov (United States)

    Rothschild, L. J.; Desmarais, D.

    1989-01-01

    The utility of measurements of C-13/C-12 ratios in organic vs inorganic deposits for searching for signs of life on early Mars is considered. It is suggested that three assumptions are necessary. First, if there was life on Mars, it caused the fractionation of carbon isotopes in analogy with past biological activity on earth. Second, the fractionation would be detectable. Third, if a fractionation would be observed, there exist no abiotic explanations for the observed fractionation pattern.

  1. CO2 production by impact in carbonates? An ATEM and stable isotope (C,O) study

    Science.gov (United States)

    Martinez, I.; Agrinier, P.; Guyot, F.; Ildefonse, PH.; Javoy, M.; Schaerer, U.; Hornemann, U.; Deutsch, A.

    1993-01-01

    Carbonates may have been a common target for large impacts on the Earth and possible related CO2 outgassing would have important consequences for the composition of the atmosphere. To estimate volatile release during such impacts, isotopic ratios (C-13/C-12 and O-18/O-16) were determined on highly shocked carbonate samples in combination with SEM and analytical transmission electron microscopy (ATEM) investigations. The study was performed on both naturally and experimentally shocked rocks, i.e. 50-60 GPa shocked limestone-dolomite fragments from the Haughton impact crater (Canada), and carbonates shocked in shock recovery experiments. For the experiments, unshocked carbonates consisting of mixture of dolomite and calcite from the Haughton area were used. Naturally shocked samples were collected in the polymict breccia near the center of the Haughton crater.

  2. Stable carbon and nitrogen isotopes of tree swallows influenced by oil sands aquatic reclamation

    International Nuclear Information System (INIS)

    This presentation reported on a study in which tree swallows (Tachycineta bicolor) were studied to evaluate reclamation strategies used by oil sand operators in Alberta. Wetland reclamation involves the transformation of tailings water and solids into functioning aquatic ecosystems. Naphthenic acids (NAs) and polycyclic aromatic compounds (PACs) in tailing/reclamation material are toxic constituents that pose concern for growth rate, reproductive function and immune function in tree swallows. Exposure to xenobiotics from these tailings-based sites was determined by increased detoxification enzyme (EROD) activity. The dietary exposure of tree swallows to oil sands constituents was determined through stable isotope analysis. Previous studies revealed trends of 13C depletion and 15N enrichment in benthic invertebrates from reclaimed wetlands on the oil sands. Since most food consumed by tree swallow nestlings is aquatic, the isotope signatures in tree swallows should provide evidence of exposure to oil sands constituents. Tree swallow feather and muscle tissues were examined in this study to determine if stable isotopes could be used to identify dietary contributions from oil sands reclamation sites versus reference sites containing no tailings materials.

  3. Stable carbon isotope fractionation in chlorinated ethene degradation by bacteria expressing three toluene oxygenases

    Directory of Open Access Journals (Sweden)

    Scott eClingenpeel

    2012-02-01

    Full Text Available One difficulty in using bioremediation at a contaminated site is demonstrating that biodegradation is actually occurring in situ. The stable isotope composition of contaminants may help with this, since they can serve as an indicator of biological activity. To use this approach it is necessary to establish how a particular biodegradation pathway affects the isotopic composition of a contaminant. This study examined bacterial strains expressing three aerobic enzymes for their effect on the 13C/12C ratio when degrading both trichloroethene (TCE and cis-1,2-dichloroethene (c-DCE: toluene 3-monoxygenase, toluene 4-monooxygenase, and toluene 2,3-dioxygenase. We found no significant differences in fractionation among the three enzymes for either compound. Aerobic degradation of c-DCE occurred with low fractionation producing δ13C enrichment factors of -0.9±0.5 to -1.2±0.5, in contrast to reported anaerobic degradation δ13C enrichment factors of -14.1‰ to -20.4‰. Aerobic degradation of TCE resulted in δ13C enrichment factors of -11.6±4.1‰ to -14.7±3.0‰ which overlap reported δ13C enrichment factors for anaerobic TCE degradation of -2.5‰ to -13.8‰. The data from this study suggest that stable isotopes could serve as a diagnostic for detecting aerobic biodegradation of TCE by toluene oxygenases at contaminated sites.

  4. Stable isotopic composition of pedogenic carbonate in soils of Minusinsk Hollow

    Science.gov (United States)

    Vasil'chuk, Jessica; Krechetov, Pavel; Budantseva, Nadine; Chizhova, Julia; Vasil'chuk, Yurij

    2016-04-01

    The purpose of the research is to characterize the isotopic composition of carbonate neoformations in soils and estimate its correlation with isotopic composition of water and parent material. The study site is located in the Minusinsk Hollow that is situated among Kuznetsk Alatau and Sayan Mountains. Three key-sites with in different parts of hollow, under mainly steppe vegetation with calciphilic grasses and diverse parent material were studied including: 1) Kazanovka Khakass state national reserve in foothills of Kuznetsk Alatau 2) Hankul salt lake that is considered as natural monument 3) region of Sayanogorsk aluminum smelter on a left bank of the Yenisei river. The samples of pedogenic and lithogenic carbonates as well as water samples were analyzed using the Delta-V mass spectrometer with a standard option of a gas bench according to standard methods. Carbonate coatings (also called pendants or cutans) is one of the most common types of carbonate neoformations occurring in the region. Fine coatings' layers one over another usually can be found on the bottom sides of rubble and gravel inside the soil profile colour varies from white to brownish and yellowish (probably depending on the impurities of organic matter). In Petric Calcisols, Chernozems and Kastanozems δ18O values of coatings vary in a rather small range from - 8.9 to - 10.1 ‰ PDB. This probably shows that their forming took place approximately in the same climatic conditions. While δ18O values of carbonate parent rocks are close to them and are vary from - 11.1 to - 11.9 ‰ PDB. Also, δ13C values of coatings strongly decrease from inner (older) to outer (younger) layers, that can indicate differences connected with the diffusion of organic material. River waters' δ18O values also show a small range from - 16.62 to - 17.66‰ SMOW, while salt lakes' waters due to the fractionation evaporation effects demonstrate much heavier values from - 4.73 to - 9.22‰ SMOW. The groundwater shows δ18O

  5. Stable isotopic composition of pedogenic carbonate in soils of Minusinsk Hollow

    Science.gov (United States)

    Vasil'chuk, Jessica; Krechetov, Pavel; Budantseva, Nadine; Chizhova, Julia; Vasil'chuk, Yurij

    2016-04-01

    The purpose of the research is to characterize the isotopic composition of carbonate neoformations in soils and estimate its correlation with isotopic composition of water and parent material. The study site is located in the Minusinsk Hollow that is situated among Kuznetsk Alatau and Sayan Mountains. Three key-sites with in different parts of hollow, under mainly steppe vegetation with calciphilic grasses and diverse parent material were studied including: 1) Kazanovka Khakass state national reserve in foothills of Kuznetsk Alatau 2) Hankul salt lake that is considered as natural monument 3) region of Sayanogorsk aluminum smelter on a left bank of the Yenisei river. The samples of pedogenic and lithogenic carbonates as well as water samples were analyzed using the Delta-V mass spectrometer with a standard option of a gas bench according to standard methods. Carbonate coatings (also called pendants or cutans) is one of the most common types of carbonate neoformations occurring in the region. Fine coatings' layers one over another usually can be found on the bottom sides of rubble and gravel inside the soil profile colour varies from white to brownish and yellowish (probably depending on the impurities of organic matter). In Petric Calcisols, Chernozems and Kastanozems δ18O values of coatings vary in a rather small range from ‑ 8.9 to ‑ 10.1 ‰ PDB. This probably shows that their forming took place approximately in the same climatic conditions. While δ18O values of carbonate parent rocks are close to them and are vary from ‑ 11.1 to ‑ 11.9 ‰ PDB. Also, δ13C values of coatings strongly decrease from inner (older) to outer (younger) layers, that can indicate differences connected with the diffusion of organic material. River waters' δ18O values also show a small range from ‑ 16.62 to ‑ 17.66‰ SMOW, while salt lakes' waters due to the fractionation evaporation effects demonstrate much heavier values from ‑ 4.73 to ‑ 9.22‰ SMOW. The

  6. A comprehensive theory for the coupling between terrestrial carbon and water cycles, supported by stable carbon isotope measurements from leaves

    Science.gov (United States)

    Wang, H.; Cornwell, W.; Wright, I. J.; Prentice, I. C.

    2014-12-01

    Stomata actively regulate the CO2 concentration inside plant leaves, which co-determines the biochemical rate of photosynthesis. Stomatal behaviour thus controls leaf-level water-use efficiency and the 'exchange rate' between the terrestrial carbon and hydrological cycles. Least-cost theory (based on the hypothesis that plants minimize the combined unit costs of maintaining the capacities for water transport and carbon uptake) predicts that (a) long-term mean values of the ci/ca ratio, i.e. the ratio of leaf-internal to ambient CO2 concentration, should be independent of both photon flux density and ca; and (b) these values should vary systematically with growing-season vapour pressure deficit, growth temperature, and atmospheric pressure. Stable carbon isotope (δ13C) measurements provide an integrated measure of the ci/ca in C3 plants. A number of previous studies have focused on the aridity dependence of δ13C. The temperature dependence seems to have been overlooked, but the elevation dependence has been known for a long time: plants at high elevations have systematically lowered ci/ca, and correspondingly increased photosynthetic capacity (Vcmax). Why this should be is a long-standing puzzle: there are various speculative explanations in the literature, and a certain amount of controversy. By contrast, least-cost theory provides quantitative predictions of all three environmental effects. We have analysed a large (3652) set of δ13C measurements from C3 plants, spanning all latitudes and biomes, and shown that these predictions are quantitatively consistent with environmental dependences that can be shown in the measurements using a generalized linear model. This analysis implies the ability to predict ci/ca ratios for large-scale terrestrial ecosystem modelling. Combined with the long-standing 'co-ordination hypothesis' for the control of photosynthetic capacity, least-cost theory provides a basis for a remarkably simple global model for gross primary

  7. Variation of terrestrial ecosystem recorded by stable carbon isotopes of fossils in northern China during the Quaternary

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Stable carbon isotopes of C3 and C4 plants have completely distinct δ13C values respectively. Carbonate in tooth enamel of herbivorous mammals is significantly and regularly enriched in 13C compared to source carbon. As a result, we can reconstruct distributions of C3 and C4 plants in geological history based on carbon isotopes of mammalian tooth enamel. Carbon isotopes of 70 mammalian tooth enamel samples from 11 Quaternary localities in northern China are analyzed. This analysis indicates that C3 plants were dominant in the terrestrial ecosystem of northern China during the Quaternary, which is completely different from Pakistan with relatively close latitudes where C4 plants were absolutely dominant. The great difference was caused by the uplift of the Tibetan Plateau. A simulation implied that a marked temperature decrease would happen in the north side of the Tibetan Plateau, but a temperature increase in the south side. The warming condition caused the transition from C3 to C4 plants in Pakistan situated in the south side of this plateau. In the north side, on the contrary, the cooling condition restrained the distribution of C4 plants. As a result, C3 plants have been dominant in northern China until now.

  8. 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)

  9. Pyrogenic carbon from tropical savanna burning: production and stable isotope composition

    Science.gov (United States)

    Saiz, G.; Wynn, J. G.; Wurster, C. M.; Goodrick, I.; Nelson, P. N.; Bird, M. I.

    2015-03-01

    Widespread burning of mixed tree-grass ecosystems represents the major natural locus of pyrogenic carbon (PyC) production. PyC is a significant, pervasive and yet poorly understood "slow-cycling" form of carbon present in the atmosphere, hydrosphere, soils and sediments. We conducted 16 experimental burns on a rainfall transect through northern Australian savannas with C4 grasses ranging from 35 to 99% of total biomass. Residues from each fire were partitioned into PyC and further into recalcitrant (HyPyC) components, with each of these fluxes also partitioned into proximal components (>125 μm), likely to remain close to the site of burning, and distal components (residence time, with shorter duration fires resulting in higher HyPyC yields. The carbon isotope (δ13C) compositions of PyC and HyPyC were generally lower by 1-3‰ relative to the original biomass, with marked depletion up to 7‰ for grasslands dominated by C4 biomass. δ13C values of CO2 produced by combustion were computed by mass balance and ranged from ~0.4 to 1.3‰. The depletion of 13C in PyC and HyPyC relative to the original biomass has significant implications for the interpretation of δ13C values of savanna soil organic carbon and of ancient PyC preserved in the geologic record, as well as for global 13C isotopic disequilibria calculations.

  10. A high resolution record of atmospheric carbon dioxide and its stable carbon isotopic composition from the penultimate glacial maximum to the glacial inception

    Directory of Open Access Journals (Sweden)

    R. Schneider

    2013-04-01

    Full Text Available The reconstruction of the stable carbon isotope evolution in atmospheric CO2 (δ13Catm, as archived in Antarctic ice cores, bears the potential to disentangle the contributions of the different carbon cycle fluxes causing past CO2 variations. Here we present a highly resolved record of δ13Catm before, during and after the Marine Isotope Stage 5.5 (155 000 to 105 000 yr BP. The record was derived with a well established sublimation method using ice from the EPICA Dome C (EDC and the Talos Dome ice cores in East Antarctica. We find an 0.4‰ offset between the mean δ13Catm level in the Penultimate (~140 000 yr BP and Last Glacial Maximum (~22 000 yr BP, which can be explained by either (i changes in the isotopic composition or (ii intensity of the carbon input fluxes to the combined ocean/atmosphere carbon reservoir or (iii by long-term peat buildup. Our isotopic data suggest that the carbon cycle evolution along Termination II and the subsequent interglacial was controlled by essentially the same processes as during the last 24 000 yr, but with different phasing and magnitudes. Furthermore, a 5000 yr lag in the CO2 decline relative to EDC temperatures is confirmed during the glacial inception at the end of MIS 5.5 (120 000 yr BP. Based on our isotopic data this lag can be explained by terrestrial carbon release and carbonate compensation.

  11. Mechanistic insights into the formation of chloroform from natural organic matter using stable carbon isotope analysis

    Science.gov (United States)

    Breider, Florian; Hunkeler, Daniel

    2014-01-01

    Chloroform can be naturally formed in terrestrial environments (e.g. forest soils, peatland) by chlorination of natural organic matter (NOM). Recently, it was demonstrated that natural and anthropogenic chloroform have a distinctly different carbon isotope signature that makes it possible to identify its origin in soil and groundwater. In order to evaluate the contribution of different functional groups to chloroform production and factors controlling the isotopic composition of chloroform, carbon isotope trends during chlorination of model compounds, soil organic matter (SOM) and humic acids were evaluated, and apparent kinetic isotope effects (AKIEs) quantified. Phenol and propanone were selected as model compounds representing common functional groups in NOM. Chlorination was induced by hypochlorous acid to mimic natural chlorination. The pH ranged between 4 and 8 to cover typical soil conditions. For each model compound and pH, different AKIEs were observed. For phenol, the AKIE was normal at pH 4 (1.0156 ± 0.0012) and inverse at pH 8 (0.9900 ± 0.0007). For 2-propoanol, an opposite pH dependence was observed with an inverse AKIE at pH 4 (0.9935 ± 0.0007) and a normal AKIE at pH 8 (1.0189 ± 0.0016). The variations of the AKIE values suggest that the rate-limiting step of the reaction is either the re-hybridization of the carbon atom involved in chloroform formation or the hydrolysis of trichloroacetyl intermediates depending on the nature of functional group and pH. The chloroform formation from humic acid and SOM gives rise to small isotope variations. A comparison of the isotopic trends of chloroform formed from humic acid and SOM with those found for the model compounds suggest that opposed AKIE associated with the chlorination of phenolic and ketone moieties of NOM partly compensate each other during chlorination of NOM indicating that different types of functional groups contribute to chloroform formation.

  12. Principles of stable isotope distribution

    CERN Document Server

    Criss, Robert E

    1999-01-01

    1. Abundance and Measurement of Stable Isotopes 1.1. Discovery of Isotopes 1.2. Nuclide Types, Abundances, and Atomic Weights 1.3. Properties and Fractionation of Isotopic Molecules 1.4. Material Balance Relationships 1.5. Mass Spectrometers 1.6. Notation and Standards 1.7. Summary 1.8. Problems References 2. Isotopic Exchange and Equilibrium Fractionation 2.1. Isotopic Exchange Reactions 2.2. Basic Equations 2.3. Molecular Models 2.4. Theory of Isotopic Fractionation 2.5. Temperature Dependence of Isotopic Fractionation Factors 2.6. Rule of the Mean 2.7. Isotopic Thermometers

  13. Springtime carbon episodes at Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    Science.gov (United States)

    Jung, J.; Kawamura, K.

    2011-05-01

    In order to investigate the carbon episodes at Gosan background super-site (33.17° N, 126.10° E) in East Asia during spring of 2007 and 2008, total suspended particles (TSP) were collected and analyzed for particulate organic carbon, elemental carbon, total carbon (TC), total nitrogen (TN), and stable carbon isotopic composition (δ13C) of TC. The carbon episodes at the Gosan site were categorized as long-range transported anthropogenic pollutant (LTP) from Asian continent, Asian dust (AD) accompanying with LTP, and local pollen episodes. The stable carbon isotopic composition of TC (δ13CTC) was found to be lowest during the pollen episodes (range: -26.2 ‰ to -23.5 ‰, avg.: -25.2 ± 0.9 ‰), followed by the LTP episodes (range: -23.5 ‰ to -23.0 ‰, avg.: -23.3 ± 0.3 ‰) and the AD episodes (range: -23.3 to -20.4 %, avg.: -21.8 ± 2.0 ‰). The δ13CTC of the airborne pollens (-28.0 ‰) collected at the Gosan site showed value similar to that of tangerine fruit (-28.1 ‰) produced from Jeju Island. Based on the carbon isotope mass balance equation and the TN and TC regression approach, we found that ∼40-45 % of TC in the TSP samples during the pollen episodes was attributed to airborne pollens from Japanese cedar trees planted around tangerine farms in Jeju Island. The δ13C of citric acid in the airborne pollens (-26.3 ‰) collected at the Gosan site was similar to that in tangerine fruit (-27.4 ‰). The negative correlation between the citric acid-carbon/TC ratios and δ13CTC were obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollens and then transported to the Gosan site. Based on the thermal evolution pattern of organic aerosols during the carbon episodes, we found that organic aerosols originated from East China are more volatile on heating and are more likely to form pyrolized organic carbon than the pollen-enriched organic aerosols and organic

  14. Field-based stable isotope analysis of carbon dioxide by mid-infrared laser spectroscopy for carbon capture and storage monitoring.

    Science.gov (United States)

    van Geldern, Robert; Nowak, Martin E; Zimmer, Martin; Szizybalski, Alexandra; Myrttinen, Anssi; Barth, Johannes A C; Jost, Hans-Jürg

    2014-12-16

    A newly developed isotope ratio laser spectrometer for CO2 analyses has been tested during a tracer experiment at the Ketzin pilot site (northern Germany) for CO2 storage. For the experiment, 500 tons of CO2 from a natural CO2 reservoir was injected in supercritical state into the reservoir. The carbon stable isotope value (δ(13)C) of injected CO2 was significantly different from background values. In order to observe the breakthrough of the isotope tracer continuously, the new instruments were connected to a stainless steel riser tube that was installed in an observation well. The laser instrument is based on tunable laser direct absorption in the mid-infrared. The instrument recorded a continuous 10 day carbon stable isotope data set with 30 min resolution directly on-site in a field-based laboratory container during a tracer experiment. To test the instruments performance and accuracy the monitoring campaign was accompanied by daily CO2 sampling for laboratory analyses with isotope ratio mass spectrometry (IRMS). The carbon stable isotope ratios measured by conventional IRMS technique and by the new mid-infrared laser spectrometer agree remarkably well within analytical precision. This proves the capability of the new mid-infrared direct absorption technique to measure high precision and accurate real-time stable isotope data directly in the field. The laser spectroscopy data revealed for the first time a prior to this experiment unknown, intensive dynamic with fast changing δ(13)C values. The arrival pattern of the tracer suggest that the observed fluctuations were probably caused by migration along separate and distinct preferential flow paths between injection well and observation well. The short-term variances as observed in this study might have been missed during previous works that applied laboratory-based IRMS analysis. The new technique could contribute to a better tracing of the migration of the underground CO2 plume and help to ensure the long

  15. Stable carbon and nitrogen isotope signatures indicate recovery of marine biota from sewage pollution at Moa Point, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Karyne M

    2003-07-01

    Stable carbon and nitrogen isotopes have been used to assess sewage contamination of a sewage outfall, discharging milli-screened effluent into Moa Point Bay, New Zealand, and monitor the recovery of flora and fauna after the outfall's closure. An initial study characterising the extent of the discharge and the effects on seaweed (Ulva lactuca L.), blue mussels (Mytilus galloprovincialis) and limpets (Cellana denticulata) from the area, showed effects of the sewage discharge on flora and fauna were localised within in the bay. The immediate area surrounding the discharge area was found to contain limited biodiversity, with an abundance of Ulva lactuca, a bright green lettuce-like seaweed, typically found in areas with high nutrient input, limpets and small blue mussels. The nitrogen isotopic signature ({delta}{sup 15}N) is shown to be a good tracer of sewage pollution in seaweed and associated grazers (i.e. limpets) as a result of the increased contribution of urea and ammonia to seawater nitrogen derived from the effluent. The carbon isotopic signature ({delta}{sup 13}C) is suggested as a more appropriate sewage tracer for mussels, which filter feed the effluent's particulate organic matter from the water. Lower carbon:nitrogen ratios were found in Ulva lactuca sampled from around the outfall region compared to uncontaminated control sites. However carbon:nitrogen ratios do not vary significantly amongst shellfish species. After closure, monitoring continued for 9 months and showed that the carbon and nitrogen isotopic signatures of algae (Ulva lactuca L.) returned to similar control site levels within 3 months. Limpet and blue mussels (Cellana denticulata and Mytilus galloprovincialis) showed slower recovery times than the Ulva lactuca, with detectable levels of the sewage-derived carbon and nitrogen remaining in the animal's tissue for up to 9 months.

  16. A new CF-IRMS system for quantifying stable isotopes of carbon monoxide from ice cores and small air samples

    Directory of Open Access Journals (Sweden)

    Z. Wang

    2010-10-01

    Full Text Available We present a new analysis technique for stable isotope ratios (δ13C and δ18O of atmospheric carbon monoxide (CO from ice core samples. The technique is an online cryogenic vacuum extraction followed by continuous-flow isotope ratio mass spectrometry (CF-IRMS; it can also be used with small air samples. The CO extraction system includes two multi-loop cryogenic cleanup traps, a chemical oxidant for oxidation to CO2, a cryogenic collection trap, a cryofocusing unit, gas chromatography purification, and subsequent injection into a Finnigan Delta Plus IRMS. Analytical precision of 0.2‰ (±1δ for δ13C and 0.6‰ (±1δ for δ18O can be obtained for 100 mL (STP air samples with CO mixing ratios ranging from 60 ppbv to 140 ppbv (~268–625 pmol CO. Six South Pole ice core samples from depths ranging from 133 m to 177 m were processed for CO isotope analysis after wet extraction. To our knowledge, this is the first measurement of stable isotopes of CO in ice core air.

  17. Bone collagen stable carbon and nitrogen isotope variability in modern South Australian mammals: A baseline for palaeoecological inferences

    International Nuclear Information System (INIS)

    Cortical bone samples were collected from a range of modern mammals at four field sites along a 1225 km north-south transect from temperate coastal to arid interior South Australia in order to address variability in stable carbon and nitrogen isotope composition. Collection sites were located along the eastern border of the state and included Mount Gambier, Karte, Plumbago and Innamincka. Mean annual rainfall along the transect ranges from 700-800 mm at Mount Gambier to 150-200 mm at Innamincka. Bone collagen carbon and nitrogen isotope values become more positive toward the arid north in relation to increasing quantities of C-4 plants and decreasing amounts of rainfall. respectively. In addition, carnivores and herbivores can be differentiated by stable nitrogen isotope values. On average, carnivore bone collagen is approximately 6 per mil more positive than that of rabbits at Mount Gambier but only 2.6 - 3.4 per mil more positive at the three arid collection sites. In general, the large eutherian herbivores have mean bone collagen δ15N values that are 1.4 - 2.3 per mil more positive than those of the marsupial herbivores. Eutherian and marsupial bone collagen δ15N differences only disappear at the most arid collection site, Innamincka

  18. Bone collagen stable carbon and nitrogen isotope variability in modern South Australian mammals: A baseline for palaeoecological inferences.

    Energy Technology Data Exchange (ETDEWEB)

    Pate, F.D.; Anson, T.J.; Noble, A.H. [Flinders Univ. of South Australia, Bedford Park, SA (Australia). Department of Archaeology; Schoeninger, M.J. [Wisconsin Univ., Madison, WI (United States). Department of Anthropology

    1997-12-31

    Cortical bone samples were collected from a range of modern mammals at four field sites along a 1225 km north-south transect from temperate coastal to arid interior South Australia in order to address variability in stable carbon and nitrogen isotope composition. Collection sites were located along the eastern border of the state and included Mount Gambier, Karte, Plumbago and Innamincka. Mean annual rainfall along the transect ranges from 700-800 mm at Mount Gambier to 150-200 mm at Innamincka. Bone collagen carbon and nitrogen isotope values become more positive toward the arid north in relation to increasing quantities of C-4 plants and decreasing amounts of rainfall. respectively. In addition, carnivores and herbivores can be differentiated by stable nitrogen isotope values. On average, carnivore bone collagen is approximately 6 per mil more positive than that of rabbits at Mount Gambier but only 2.6 - 3.4 per mil more positive at the three arid collection sites. In general, the large eutherian herbivores have mean bone collagen {delta}15N values that are 1.4 - 2.3 per mil more positive than those of the marsupial herbivores. Eutherian and marsupial bone collagen {delta}15N differences only disappear at the most arid collection site, Innamincka.

  19. Trophic relationships and habitat preferences of delphinids from the southeastern Brazilian coast determined by carbon and nitrogen stable isotope composition.

    Directory of Open Access Journals (Sweden)

    Tatiana Lemos Bisi

    Full Text Available To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ(13C and nitrogen (δ(15N isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ(13C and δ(15N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ(13C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ(13C value, while oceanic species showed significantly lower δ(13C values. The highest δ(15N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ(15N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ(13C values, but similar δ(15N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ(13C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area.

  20. Trophic relationships and habitat preferences of delphinids from the southeastern Brazilian coast determined by carbon and nitrogen stable isotope composition.

    Science.gov (United States)

    Bisi, Tatiana Lemos; Dorneles, Paulo Renato; Lailson-Brito, José; Lepoint, Gilles; Azevedo, Alexandre de Freitas; Flach, Leonardo; Malm, Olaf; Das, Krishna

    2013-01-01

    To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ(13)C and δ(15)N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ(13)C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ(13)C value, while oceanic species showed significantly lower δ(13)C values. The highest δ(15)N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ(15)N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ(13)C values, but similar δ(15)N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ(13)C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area. PMID:24358155

  1. Stable isotope analysis in the ivory

    Energy Technology Data Exchange (ETDEWEB)

    Ishibashi, H.; Koike, H. [Graduate School of Social and Cultural Studies, Kyushu University, Fukuoka (Japan); Takeuchi, Takayuki [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst

    2001-01-01

    Stable isotope ratio in an ivory collagen reflects the isotope ratio of the plants they are eaten by the elephant. From the stable isotope ratios of carbon ({delta} {sup 13}C) and nitrogen ({delta} {sup 15}N) in a ivory collagen the habitat of the elephant can be estimated. The 118 pieces of the ivory were analyzed for detecting the isotope ratios, which are kept in the Kruger National Park, South Africa. The result shows the grouping of the ivory related to the area in which elephant were captured. (H. Katsuta)

  2. 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)

  3. Preservation Methods Alter Carbon and Nitrogen Stable Isotope Values in Crickets (Orthoptera: Grylloidea.

    Directory of Open Access Journals (Sweden)

    Fabiene Maria Jesus

    Full Text Available Stable isotope analysis (SIA is an important tool for investigation of animal dietary habits for determination of feeding niche. Ideally, fresh samples should be used for isotopic analysis, but logistics frequently demands preservation of organisms for analysis at a later time. The goal of this study was to establish the best methodology for preserving forest litter-dwelling crickets for later SIA analysis without altering results. We collected two cricket species, Phoremia sp. and Mellopsis doucasae, from which we prepared 70 samples per species, divided among seven treatments: (i freshly processed (control; preserved in fuel ethanol for (ii 15 and (iii 60 days; preserved in commercial ethanol for (iv 15 and (v 60 days; fresh material frozen for (vi 15 and (vii 60 days. After oven drying, samples were analyzed for δ15N, δ13C values, N(%, C(% and C/N atomic values using continuous flow isotope ratio mass spectrometry. All preservation methods tested, significantly impacted δ13C and δ15N and C/N atomic values. Chemical preservatives caused δ13C enrichment as great as 1.5‰, and δ15N enrichment as great as 0.9‰; the one exception was M. doucasae stored in ethanol for 15 days, which had δ15N depletion up to 1.8‰. Freezing depleted δ13C and δ15N by up to 0.7 and 2.2‰, respectively. C/N atomic values decreased when stored in ethanol, and increased when frozen for 60 days for both cricket species. Our results indicate that all preservation methods tested in this study altered at least one of the tested isotope values when compared to fresh material (controls. We conclude that only freshly processed material provides adequate SIA results for litter-dwelling crickets.

  4. Potential of Stable Carbon and Oxygen Isotope Variations of Speleothems from Andaman Islands, India, for Paleomonsoon Reconstruction

    Directory of Open Access Journals (Sweden)

    Amzad H. Laskar

    2011-01-01

    Full Text Available The Indian monsoon activity, coinciding with the Inter-Tropical Convective Zone (ITCZ, progresses from the southern Indian Ocean during the boreal summer and withdraws towards the south in winter. Islands situated to the south of India receive, therefore, the first and last showers of the monsoon; speleothems in such islands have not yet been explored for their potential to reconstruct past monsoon rainfall. Here, we present the first measurements of stable carbon and oxygen isotopic compositions (δ13C and δ18O of a stalagmite collected from the Baratang Island of Andamans, along with new data on δ18O of modern monsoon precipitation (May to July 2010. The aim was to detect (i whether these samples are amenable to dating using 14C, (ii whether their oxygen isotopes indicate precipitation under isotopic equilibrium, and (iii if (i and (ii above are true, can we reconstruct monsoon activity during the past few millennia? Our results indicate that while δ18O of speleothem does show evidence for precipitation under isotopic equilibrium; dating by 14C shows inversions due to varying contributions from dead carbon. The present work highlights the problems and prospects of speleothem paleomonsoon research in these islands.

  5. Mineralogy and stable isotope compositions of carbonate and sulphide minerals of carbonate crusts associated with gas hydrate-forming cold vents from the NE Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Conly, A.G. [Lakehead Univ., Thunder Bay, ON (Canada). Dept. of Geology; Scott, S.D. [Toronto Univ., ON (Canada). Dept. of Geology; Riedel, M. [Natural Resources Canada, Sidney, BC (Canada). Geological Survey of Canada, Pacific Geoscience Centre

    2005-07-01

    In 2001, the ROPOS submersible sampled 21 specimens of carbonate crusts from 2 gas hydrate fields located offshore Vancouver Island on the northeast Pacific continental margin. The mineralogy and stable isotopic composition of carbonate and sulphide minerals were used to evaluate petrogenesis and the relationship to associated gas hydrate occurrences. The crusts form the upper surface of carbonate and pelagic mud mounds within the gas hydrate fields. The crusts are made up of micritic carbonate with a highly variable morphology that includes blocky, fissile, nodular and mudcemented brecciated forms. The crusts include micritic calcite and dolomite/ferroan dolomite, with up to 30 per cent detrital and authigenic silicates. The finely disseminated sulphide minerals include pyrite and trace amounts of sphalerite. Bulk-rock chemical compositions are mainly homogeneous. Any variations reflect the calcite:dolomite and carbonate:silicate ratios. The {delta}13 C values for bulk carbonate (calcite and dolomite) were presented. No definitive correlation between {delta}13 C value and carbonate mineralogy was noted, but calcite-dominant samples were found to be more depleted. The {delta}34 S values for sulphide were also presented. The carbon isotopic composition of the carbonate is associated with the balance of inorganic and organic carbon species. Bacterial sulphate reduction and/or bacterial fermentation and carbonate reduction processes responsible for the production of methane were found to control the {delta}13 C of the carbon dioxide reservoir in gas hydrate environments. It was shown that methane was the carbon source involved in bacterial sulphate reduction and that the isotopic composition of the CO{sub 2} reservoir may be controlled by fractionation during bacterial carbonate reduction. The range in sulphur isotopes correlates with the bacterial sulphate reduction under partially closed conditions, where the rate of diffusion of sulphate is less than the rate of

  6. Microbial food web mapping: linking carbon cycling and community structure in soils through pyrosequencing enabled stable isotope probing

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, Daniel H. [Cornell Univ., Ithaca, NY (United States)

    2015-03-15

    Soil represents a massive reservoir of active carbon and climate models vary dramatically in predicting how this carbon will respond to climate change over the coming century. A major cause of uncertainty is that we still have a very limited understand the microorganisms that dominate the soil carbon cycle. The vast majority of soil microbes cannot be cultivated in the laboratory and the diversity of organisms and enzymes that participate in the carbon cycle is staggeringly complex. We have developed a new toolbox for exploring the carbon cycle and the metabolic and ecological characteristics of uncultivated microorganisms. The high-resolution nucleic acid stable isotope probing approach that we have developed makes it possible to characterize microbial carbon cycling dynamics in soil. The approach allows us to track multiple 13C-labeled substrates into thousands of microbial taxa over time. Using this approach we have discovered several major lineages of uncultivated microorganisms that participate in cellulose metabolism and are found widely in soils (including Verrucomicrobia and Chloroflexi, which have not previously been implicated as major players in the soil carbon cycle). Furthermore, isotopic labelling of nucleic acids enables community genomics and permits genome fragment binning for a majority of these cellulolytic microorganisms allowing us to explore the metabolic underpinnings of cellulose degradation. This approach has allowed us to describe unexpected dynamics of carbon metabolism with different microbial taxa exhibiting characteristic patterns of carbon substrate incorporation, indicative of distinct ecological strategies. The data we describe allows us to characterize the activity of novel microorganisms as they occur in the environment and these data provide a basis for understanding how the physiological traits of discrete microorganisms sum to govern the complex responses of the soil carbon cycle.

  7. Trophic ecology and vertical patterns of carbon and nitrogen stable isotopes in zooplankton from oxygen minimum zone regions

    Science.gov (United States)

    Williams, Rebecca L.; Wakeham, Stuart; McKinney, Rick; Wishner, Karen F.

    2014-08-01

    The unique physical and biogeochemical characteristics of oxygen minimum zones (OMZs) influence plankton ecology, including zooplankton trophic webs. Using carbon and nitrogen stable isotopes, this study examined zooplankton trophic webs in the Eastern Tropical North Pacific (ETNP) OMZ. δ13C values were used to indicate zooplankton food sources, and δ15N values were used to indicate zooplankton trophic position and nitrogen cycle pathways. Vertically stratified MOCNESS net tows collected zooplankton from 0 to 1000 m at two stations along a north-south transect in the ETNP during 2007 and 2008, the Tehuantepec Bowl and the Costa Rica Dome. Zooplankton samples were separated into four size fractions for stable isotope analyses. Particulate organic matter (POM), assumed to represent a primary food source for zooplankton, was collected with McLane large volume in situ pumps. The isotopic composition and trophic ecology of the ETNP zooplankton community had distinct spatial and vertical patterns influenced by OMZ structure. The most pronounced vertical isotope gradients occurred near the upper and lower OMZ oxyclines. Material with lower δ13C values was apparently produced in the upper oxycline, possibly by chemoautotrophic microbes, and was subsequently consumed by zooplankton. Between-station differences in δ15N values suggested that different nitrogen cycle processes were dominant at the two locations, which influenced the isotopic characteristics of the zooplankton community. A strong depth gradient in zooplankton δ15N values in the lower oxycline suggested an increase in trophic cycling just below the core of the OMZ. Shallow POM (0-110 m) was likely the most important food source for mixed layer, upper oxycline, and OMZ core zooplankton, while deep POM was an important food source for most lower oxycline zooplankton (except for samples dominated by the seasonally migrating copepod Eucalanus inermis). There was no consistent isotopic progression among the four

  8. Nuclear physics and stable isotopes; Physique nucleaire et isotopes stables

    Energy Technology Data Exchange (ETDEWEB)

    Goutte, D. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee

    1994-12-31

    The aim of this paper is to show that fundamental research in nuclear physics requires utilization of stable isotopes; stable isotopes are essential as target material since a large quantity of nucleus have to be studied in order to appreciate all the complexity of the nuclear structure, but also as a tool, such as beams, for the same purpose. Examples are given with samarium, tin and germanium isotopes. 7 figs.

  9. Tracing carbon flow in an arctic marine food web using fatty acid-stable isotope analysis.

    Science.gov (United States)

    Budge, S M; Wooller, M J; Springer, A M; Iverson, S J; McRoy, C P; Divoky, G J

    2008-08-01

    Global warming and the loss of sea ice threaten to alter patterns of productivity in arctic marine ecosystems because of a likely decline in primary productivity by sea ice algae. Estimates of the contribution of ice algae to total primary production range widely, from just 3 to >50%, and the importance of ice algae to higher trophic levels remains unknown. To help answer this question, we investigated a novel approach to food web studies by combining the two established methods of stable isotope analysis and fatty acid (FA) analysis--we determined the C isotopic composition of individual diatom FA and traced these biomarkers in consumers. Samples were collected near Barrow, Alaska and included ice algae, pelagic phytoplankton, zooplankton, fish, seabirds, pinnipeds and cetaceans. Ice algae and pelagic phytoplankton had distinctive overall FA signatures and clear differences in delta(13)C for two specific diatom FA biomarkers: 16:4n-1 (-24.0+/-2.4 and -30.7+/-0.8 per thousand, respectively) and 20:5n-3 (-18.3+/-2.0 and -26.9+/-0.7 per thousand, respectively). Nearly all delta(13)C values of these two FA in consumers fell between the two stable isotopic end members. A mass balance equation indicated that FA material derived from ice algae, compared to pelagic diatoms, averaged 71% (44-107%) in consumers based on delta(13)C values of 16:4n-1, but only 24% (0-61%) based on 20:5n-3. Our estimates derived from 16:4n-1, which is produced only by diatoms, probably best represented the contribution of ice algae relative to pelagic diatoms. However, many types of algae produce 20:5n-3, so the lower value derived from it likely represented a more realistic estimate of the proportion of ice algae material relative to all other types of phytoplankton. These preliminary results demonstrate the potential value of compound-specific isotope analysis of marine lipids to trace C flow through marine food webs and provide a foundation for future work. PMID:18481094

  10. 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

  11. 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

    NARCIS (Netherlands)

    Schimmelrnann, 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; Groeing, Manfred; Helie, Jean-Francois; Herrero-Martin, Sara; Meijer, Harro A. J.; Sauer, Peter E.; Sessions, Alex L.; Werner, Roland A.

    2016-01-01

    An international project developed, quality-tested, and determined isotope-delta 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-60

  12. Sources and transportation of suspended matter and sediment in the southern Yellow Sea: Evidence from stable carbon isotopes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The concentrations of total suspended matter (TSM) and the compositions of organic stable carbon isotopes of TSM and bottom sediments were analyzed to study the sources of TSM and sediments and the transportation processes. For this study, 284 TSM samples and 64 sediment ones taken from 67 stations along 7 transects and in 5 layers were collected in the southern Yellow Sea on the cruise in May, 1998. The main sediment transportation pattern in the southern Yellow Sea was obtained by analyzing the distribution characteristics of TSM concentration and particulate organic carbon Δ13c values. It was confirmed from the pattern that the bottom layer plays a more important role than the surface one in the transportation processes of terrigenous material to the central deep-water area of the southern Yellow Sea. The Yellow Sea circulation is an important control factor in determining the sediment transportation pattern in the southern Yellow Sea. The carbon isotope signals of sedimentary organic matter confirmed that the main material in sediments with high sedimentation rate in the Shandong subaqueous delta originated from the modern Yellow River. The terrigenous sediments in the deep-water area of the southern Yellow Sea are mainly from the abandoned Yellow River and the modern Yellow River, and a small portion of them are from the modern Yangtze material. The amount of terrigenous material from Korean Peninsula and its influen- ce range are relatively limited. The conclusions derived from TSM and stable carbon isotopes were further confirmed by another independent material source tracer--PAHs.

  13. Demonstration of Carbon Catabolite Repression in Naphthalene Degrading Soil Bacteria via Raman Spectroscopy Based Stable Isotope Probing.

    Science.gov (United States)

    Kumar B N, Vinay; Guo, Shuxia; Bocklitz, Thomas; Rösch, Petra; Popp, Jürgen

    2016-08-01

    Carbon catabolite repression (CCR) is a regulatory phenomenon occurring in both lower organisms like bacteria and higher organisms like yeast, which allows them to preferentially utilize a specific carbon source to achieve highest metabolic activity and cell growth. CCR has been intensely studied in the model organisms Escherichia coli and Bacillus subtilis by following diauxic growth curves, assays to estimate the utilization or depletion of carbon sources, enzyme assays, Western blotting and mass spectrometric analysis to monitor and quantify the involvement of specific enzymes and proteins involved in CCR. In this study, we have visualized this process in three species of naphthalene degrading soil bacteria at a single cell level via Raman spectroscopy based stable isotope probing (Raman-SIP) using a single and double labeling approach. This is achieved using a combination of (2)H and (13)C isotope labeled carbon sources like glucose, galactose, fructose, and naphthalene. Time dependent metabolic flux of (13)C and (2)H isotopes has been followed via semi quantification and 2D Raman correlation analysis. For this, the relative intensities of Raman marker bands corresponding to (2)H and (13)C incorporation in newly synthesized macromolecules like proteins and lipids have been utilized. The 2D correlation analysis of time dependent Raman spectra readily identified small sequential changes resulting from isotope incorporation. Overall, we show that Raman-SIP has the potential to be used to obtain information about regulatory processes like CCR in bacteria at a single cell level within a time span of 3 h in fast growing bacteria. We also demonstrate the potential of this approach in identifying the most efficient naphthalene degraders asserting its importance for use in bioremediation. PMID:27305464

  14. Stable Carbon Isotope Evidence for Neolithic and Bronze Age Crop Water Management in the Eastern Mediterranean and Southwest Asia.

    Directory of Open Access Journals (Sweden)

    Michael P Wallace

    Full Text Available In a large study on early crop water management, stable carbon isotope discrimination was determined for 275 charred grain samples from nine archaeological sites, dating primarily to the Neolithic and Bronze Age, from the Eastern Mediterranean and Western Asia. This has revealed that wheat (Triticum spp. was regularly grown in wetter conditions than barley (Hordeum sp., indicating systematic preferential treatment of wheat that may reflect a cultural preference for wheat over barley. Isotopic analysis of pulse crops (Lens culinaris, Pisum sativum and Vicia ervilia indicates cultivation in highly varied water conditions at some sites, possibly as a result of opportunistic watering practices. The results have also provided evidence for local land-use and changing agricultural practices.

  15. Concentration and stable carbon isotopic composition of CO2 in cave air of Postojnska jama, Slovenia

    Directory of Open Access Journals (Sweden)

    Magda Mandic

    2013-09-01

    Full Text Available Partial pressure of CO2 (pCO2 and its isotopic composition (δ13CairCO2 were measured in Postojnska jama, Slovenia, at 10 locations inside the cave and outside the cave during a one-year period. At all interior locations the pCO2 was higher and δ13CairCO2 lower than in the outside atmosphere. Strong seasonal fluctuations in both parameters were observed at locations deeper in the cave, which are isolated from the cave air circulation. By using a binary mixing model of two sources of CO2, one of them being the atmospheric CO2, we show that the excess of CO2 in the cave air has a δ13C value of -23.3 ± 0.7 ‰, in reasonable agreement with the previously measured soil-CO2 δ13C values. The stable isotope data suggest that soil CO2 is brought to the cave by drip water.

  16. 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.

  17. 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

  18. Variation in stable carbon isotopes in organic matter from the Gunflint Iron Formation. [Precambrian rock analysis

    Science.gov (United States)

    Barghoorn, E. S.; Knoll, A. H.; Dembicki, H., Jr.; Meinschein, W. G.

    1977-01-01

    Results are presented for an isotopic analysis of the kerogen separated from 15 samples of the Gunflint Iron Formation, Ontario, and the conformably overlying Rove Formation. Reasons for which the Gunflint Iron Formation is suitable for such a study of a single Precambrian formation are identified. The general geology of the formation is outlined along with sample selection, description, and preparation. Major conclusions are that the basal Gunflint algal chert and shale facies are depleted in C-13 relative to the chert-carbonate and taconite facies, that differences in the delta C-13 values between Gunflint facies correlate with marked differences in their biological source materials as evidenced by their respective microbiotas, that the anthraxolites are anomalously depleted in C-13 relative to the kerogen of their encompassing cherts and shales, and that the effects of igneous intrusion and concomitant thermal alteration are shown by a marked loss of C-12 at the contact. The demonstration that not all kerogens are isotopically alike stresses the importance of facies data to the interpretation of C-13/C-12 ratios of ancient organic matter.

  19. Pyrogenic carbon from tropical savanna burning: production and stable isotope composition

    Directory of Open Access Journals (Sweden)

    G. Saiz

    2014-10-01

    C4 grasses ranging from 35 to 99% of total biomass. Residues from each fire were partitioned into PyC and further into recalcitrant (HyPyC components, with each of these also partitioned into proximal (> 125 μm and distal (13C compositions of PyC and HyPyC were generally lower by 1–3‰ relative to the original biomass, with marked depletion up to 7 ‰ for grasslands dominated by C4 biomass. δ13C values of CO2 produced by combustion was computed by mass balance and ranged from ~0.4 to 1.3‰. The depletion of 13C in PyC and HyPyC relative to the original biomass has significant implications for the interpretation of δ13C values of savanna soil organic carbon and of ancient PyC preserved in the geologic record, and for global 13C isotopic disequilibria calculations.

  20. Stable Carbon Isotope Discrimination by Form IC Rubisco Enzymes of the Extremely Metabolically Versatile Rhodobacter sphaeroides and Ralstonia eutropha}

    Science.gov (United States)

    Thomas, P. J.; Boller, A. J.; Zhao, Z.; Tabita, F. R.; Cavanaugh, C. M.; Scott, K. M.

    2006-12-01

    Variations in the relative amounts of 12C and 13C in microbial biomass can be used to infer the pathway(s) autotrophs use to fix and assimilate dissolved inorganic carbon. Discrimination against 13C by the enzymes catalyzing autotrophic carbon fixation is a major factor dictating biomass stable carbon isotopic compositions (δ13C = {[13C/12Csample/13C/12Cstandard] - 1} × 1000). Five different forms of RubisCO (IA, IB, IC, ID, and II) are utilized by algae and autotrophic bacteria reliant on the Calvin-Benson cycle for carbon fixation. To date, isotope discrimination has been measured for form IA, IB, and II RubisCOs, and their ɛ values (={[12k/13k] - 1} × 1000; 12k and 13k = rates of 12C and 13C fixation) range from 18 to 29‰, explaining the variation in biomass δ13C values of autotrophs utilizing these enzymes. Isotope discrimination by form IC RubisCO has not been measured, despite the presence of this enzyme in many proteobacteria of ecological interest, including marine manganese-oxidizing bacteria, some nitrifying and nitrogen-fixing bacteria, and extremely metabolically versatile organisms such as Rhodobacter sphaeroides and Ralstonia eutropha. The purpose of this work was to determine the ɛ values for form IC RubisCO enzymes from R. sphaeroides and R. eutropha. Recombinant form IC RubisCOs were purified by conventional column chromatography procedures. Assay conditions (pH, dissolved inorganic carbon concentration) were tested to determine which parameters were conducive to the high rates of carbon fixation necessary for ɛ determination. Under standard conditions (pH 8.5 and 5 mM DIC), form IC RubisCO activities were sufficient for ɛ determination. Experiments are currently being conducted to measure the ɛ values of these enzymes. Sampling the full phylogenetic breadth of RubisCO enzymes for isotopic discrimination makes it possible to constrain the range of δ13C values of organisms fixing carbon via the Calvin-Benson cycle. These results are

  1. Biomarkers and compound-specific stable carbon isotope of n-alkanes in crude oils from Eastern Llanos Basin, Colombia

    Science.gov (United States)

    Cortes, Jorge E.; Rincon, Jose M.; Jaramillo, Jose M.; Philp, R. Paul; Allen, Jon

    2010-03-01

    Representative samples of crude oils from Cusiana, Cupiagua, Apiay, Castilla and Chichimene fields in the Eastern Llanos Basin of Colombia were analyzed to determine its compound-specific stable carbon isotope composition (CSIA) using gas chromatography-isotopic ratio-mass spectrometry (GC-IRMS). GC-IRMS analyses of n-alkanes allowed differentiating between Cretaceous and Cretaceous/Tertiary oil samples. Cretaceous sourced samples have δ13C-enriched values than Cretaceous/Tertiary sourced samples; the heavier isotope composition of these samples is due to their major terrigenous organic matter input. Their isotope distribution patterns suggest significant algal and/or bacterial contribution (marine origin). The analysis of the n-alkane fractions by GC-IRMS confirms that the organic matter has marine origin in those samples from Cusiana, Cupiagua and Apiay while Castilla and Chichimene have marine origin with terrestrial inputs. The results were confirmed by gas chromatography/FID and gas chromatography/mass spectrometry (GC/MS). Basic geochemical composition show that samples from Cupiagua/Cusiana fields and Apiay/Castilla/Chichimene fields in the Llanos basin, Colombia present different characteristics reflecting a specific for each depositional environment.

  2. Stable carbon isotope values document how a Late Holocene expansion in grasslands impacted vertebrates in northwestern Madagascar

    Science.gov (United States)

    Crowley, B. E.; Samonds, K.

    2012-12-01

    Madagascar is home to some of the world's most distinctive plants and animals. Unfortunately, forest loss and habitat degradation has had a dramatic impact on both floral and faunal communities. Here we use carbon isotope values in radiocarbon-dated bones to examine how the vertebrate community at Anjohibe Cave, northwestern Madagascar, responded to a Late Holocene increase in C4 grass abundance. Our data demonstrate that major changes in the vegetation and animal community are recent phenomena at Anjohibe. Extinct lemurs and hippopotamuses were present until ca. 1500 years ago. These taxa relied exclusively on C3 resources. Locally extirpated fauna were present until 300 years ago. The majority of these species also relied on C3 resources. Their presence strongly suggests that the region surrounding the cave was more wooded than it is now, possibly as recently as 300 years ago. All introduced individuals are modern. Rats (Rattus sp.), shrews (Suncus murinus), and the giant frog Hoplobatrachus cf. tigrinus, have remarkably high carbon isotope values, implicating substantial ingestion of C4 foods. It is possible that grass abundance has increased dramatically in the past 100 years. Alternatively, opportunistically granivorous rats and shrews may selectively consume seeds from C4 grasses. In agreement with previous studies, stable isotope data reveal details of vegetation and faunal turnover in Northwestern Madagascar. Grasses have increased, forest dwelling species have vanished, and introduced taxa are exploiting a novel niche.

  3. A First Look at Carbon and Oxygen Stable Isotope Measurements of Martian Atmospheric C02 by the Phoenix Lander

    Science.gov (United States)

    Niles, P.B.; Ming, D.W.; Boynton, W.V.; Hamara, D.; Hoffman, J.H.

    2009-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars. The isotopic composition of the martian atmosphere has been measured using a number of different methods (Table 1), however a precise value (carbonates in martian meteorites it has been supposed that the martian atmosphere was enriched in delta(sup 13)C. This was supported by measurements of trapped CO2 gas in EETA 79001[2] which showed elevated delta(sup 13)C values (Table 1). More recently, Earth-based spectroscopic measurements of the martian atmosphere have measured the martian CO2 to be depleted in delta(sup 13)C relative to CO2 in the terrestrial atmosphere. The spectroscopic measurements performed by Krasnopolsky et al. were reported with approx.2% uncertainties which are much smaller than the Viking measurements, but still remain very large in comparison to the magnitude of carbon and oxygen isotope fractionations under martian surface conditions. The Thermal Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander included a magnetic sector mass spectrometer (EGA) which had the goal of measuring the isotopic composition of martian atmospheric CO2 to within 0.5%. The mass spectrometer is a miniature magnetic sector instrument intended to measure both the martian atmosphere as well as gases evolved from heating martian soils. Ions produced in the ion source are drawn out by a high voltage and focused by a magnetic field onto a set of collector slits. Four specific trajectories are selected to cover the mass ranges, 0.7 - 4, 7 - 35, 14 - 70, and 28 - 140 Da. Using four channels reduces the magnitude of the mass scan and provides simultaneous coverage of the mass ranges. Channel electron multiplier (CEM) detectors that operate in the pulse counting mode detect the ion beams.

  4. Pressurized laboratory experiments show no stable carbon isotope fractionation of methane during gas hydrate dissolution and dissociation.

    Science.gov (United States)

    Lapham, Laura L; Wilson, Rachel M; Chanton, Jeffrey P

    2012-01-15

    The stable carbon isotopic ratio of methane (δ(13)C-CH(4)) recovered from marine sediments containing gas hydrate is often used to infer the gas source and associated microbial processes. This is a powerful approach because of distinct isotopic fractionation patterns associated with methane production by biogenic and thermogenic pathways and microbial oxidation. However, isotope fractionations due to physical processes, such as hydrate dissolution, have not been fully evaluated. We have conducted experiments to determine if hydrate dissolution or dissociation (two distinct physical processes) results in isotopic fractionation. In a pressure chamber, hydrate was formed from a methane gas source at 2.5 MPa and 4 °C, well within the hydrate stability field. Following formation, the methane source was removed while maintaining the hydrate at the same pressure and temperature which stimulated hydrate dissolution. Over the duration of two dissolution experiments (each ~20-30 days), water and headspace samples were periodically collected and measured for methane concentrations and δ(13)C-CH(4) while the hydrate dissolved. For both experiments, the methane concentrations in the pressure chamber water and headspace increased over time, indicating that the hydrate was dissolving, but the δ(13)C-CH(4) values showed no significant trend and remained constant, within 0.5‰. This lack of isotope change over time indicates that there is no fractionation during hydrate dissolution. We also investigated previous findings that little isotopic fractionation occurs when the gas hydrate dissociates into gas bubbles and water due to the release of pressure. Over a 2.5 MPa pressure drop, the difference in the δ(13)C-CH(4) was dissociates and demonstrated that there is no fractionation when the hydrate dissolves. Therefore, measured δ(13)C-CH(4) values near gas hydrates are not affected by physical processes, and can thus be interpreted to result from either the gas source or

  5. Online Stable Isotope Analysis of Dissolved Organic Carbon Size Classes Using Size Exclusion Chromatography Coupled to an Isotope Ratio Mass Spectrometer

    Digital Repository Service at National Institute of Oceanography (India)

    Malik, A.; Scheibe, A.; LokaBharathi, P.A.; Gleixner, G.

    been a technological leap in carbon stable isotope analysis of aqueous mixtures.21 This system allows efficient chromatographic separation of injected mixtures which then are sequentially oxidized under acidic conditions and the resulting CO2 after...,Thermo Fisher Scientific). 100 µL of analyte was injected into the mobile phase maintained at a constant flow rate of 500 µL/min using a Surveyor MS pump.Various eluents were tested for efficient separation of DOC; these included double distilled water, KH2PO...

  6. Stable carbon isotope fractionation of organic cyst-forming dinoflagellates: Evaluating the potential for a CO2 proxy

    Science.gov (United States)

    Hoins, Mirja; Van de Waal, Dedmer B.; Eberlein, Tim; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy

    2015-07-01

    Over the past decades, significant progress has been made regarding the quantification and mechanistic understanding of stable carbon isotope fractionation (13C fractionation) in photosynthetic unicellular organisms in response to changes in the partial pressure of atmospheric CO2 (pCO2). However, hardly any data is available for organic cyst-forming dinoflagellates while this is an ecologically important group with a unique fossil record. We performed dilute batch experiments with four harmful dinoflagellate species known for their ability to form organic cysts: Alexandrium tamarense, Scrippsiella trochoidea, Gonyaulax spinifera and Protoceratium reticulatum. Cells were grown at a range of dissolved CO2 concentrations characterizing past, modern and projected future values (∼5-50 μmol L-1), representing atmospheric pCO2 of 180, 380, 800 and 1200 μatm. In all tested species, 13C fractionation depends on CO2 with a slope of up to 0.17‰ (μmol L)-1. Even more consistent correlations were found between 13C fractionation and the combined effects of particulate organic carbon quota (POC quota; pg C cell-1) and CO2. Carbon isotope fractionation as well as its response to CO2 is species-specific. These results may be interpreted as a first step towards a proxy for past pCO2 based on carbon isotope ratios of fossil organic dinoflagellate cysts. However, additional culture experiments focusing on environmental variables other than pCO2, physiological underpinning of the recorded response, testing for possible offsets in 13C values between cells and cysts, as well as field calibration studies are required to establish a reliable proxy.

  7. Stable carbon isotope discrimination and microbiology of methane formation in tropical anoxic lake sediments

    Science.gov (United States)

    Conrad, R.; Noll, M.; Claus, P.; Klose, M.; Bastos, W. R.; Enrich-Prast, A.

    2011-03-01

    Methane is an important end product of degradation of organic matter in anoxic lake sediments. Methane is mainly produced by either reduction of CO2 or cleavage of acetate involving different methanogenic archaea. The contribution of the different methanogenic paths and of the diverse bacteria and archaea involved in CH4 production exhibits a large variability that is not well understood. Lakes in tropical areas, e.g. in Brazil, are wetlands with high potential impact on the global CH4 budget. However, they have hardly been studied with respect to methanogenesis. Therefore, we used samples from 16 different lake sediments in the Pantanal and Amazon region of Brazil to measure production of CH4, CO2, analyze the content of 13C in the products and in intermediately formed acetate, determine the abundance of bacterial and archaeal microorgansisms and their community composition and diversity by targeting the genes of bacterial and archaeal ribosomal RNA and of methyl coenzyme M reductase, the key enzyme of methanogenic archaea. These experiments were done in the presence and absence of methyl fluoride, an inhibitor of acetoclastic methanogenesis. While production rates of CH4 and CO2 were correlated to the content of organic matter and the abundance of archaea in the sediment, values of 13C in acetate, CO2, and CH4 were related to the 13C content of organic matter and to the path of CH4 production with its intrinsic carbon isotope fractionation. Isotope fractionation was small (average 10‰) for conversion of Corg to acetate-methyl, which was hardly further fractionated during CH4 production. However, fractionation was strong for CO2 conversion to CH4 (average 75‰), which generally accounted for >50% of total CH4 production. Canonical correspondence analysis did not reveal an effect of microbial community composition, despite the fact that it exhibited a pronounced variability among the different sediments.

  8. 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

  9. Variation in the stable carbon and nitrogen isotope composition of plants and soil along a precipitation gradient in northern China.

    Directory of Open Access Journals (Sweden)

    Jian-Ying Ma

    Full Text Available Water availability is the most influential factor affecting plant carbon (δ(13C and nitrogen (δ(15N isotope composition in arid and semi-arid environments. However, there are potential differences among locations and/or species in the sensitivity of plant δ(13C and δ(15N to variation in precipitation, which are important for using stable isotope signatures to extract paleo-vegetation and paleo-climate information. We measured δ(13C and δ(15N of plant and soil organic matter (SOM samples collected from 64 locations across a precipitation gradient with an isotherm in northern China. δ(13C and δ(15N for both C(3 and C(4 plants decreased significantly with increasing mean annual precipitation (MAP. The sensitivity of δ(13C to MAP in C(3 plants (-0.6 ± 0.07‰/100 mm was twice as high as that in C(4 plants (-0.3 ± 0.08‰/100 mm. Species differences in the sensitivity of plant δ(13C and δ(15N to MAP were not observed among three main dominant plants. SOM became depleted in (13C with increasing MAP, while no significant correlations existed between δ(15N of SOM and MAP. We conclude that water availability is the primary environmental factor controlling the variability of plant δ(13C and δ(15N and soil δ(13C in the studied arid and semi-arid regions. Carbon isotope composition is useful for tracing environmental precipitation changes. Plant nitrogen isotope composition can reflect relative openness of ecosystem nitrogen cycling.

  10. 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

  11. Springtime carbon episodes at Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    Directory of Open Access Journals (Sweden)

    J. Jung

    2011-05-01

    Full Text Available In order to investigate the carbon episodes at Gosan background super-site (33.17° N, 126.10° E in East Asia during spring of 2007 and 2008, total suspended particles (TSP were collected and analyzed for particulate organic carbon, elemental carbon, total carbon (TC, total nitrogen (TN, and stable carbon isotopic composition (δ13C of TC. The carbon episodes at the Gosan site were categorized as long-range transported anthropogenic pollutant (LTP from Asian continent, Asian dust (AD accompanying with LTP, and local pollen episodes. The stable carbon isotopic composition of TC (δ13CTC was found to be lowest during the pollen episodes (range: −26.2 ‰ to −23.5 ‰, avg.: −25.2 ± 0.9 ‰, followed by the LTP episodes (range: −23.5 ‰ to −23.0 ‰, avg.: −23.3 ± 0.3 ‰ and the AD episodes (range: −23.3 to −20.4 %, avg.: −21.8 ± 2.0 ‰. The δ13CTC of the airborne pollens (−28.0 ‰ collected at the Gosan site showed value similar to that of tangerine fruit (−28.1 ‰ produced from Jeju Island. Based on the carbon isotope mass balance equation and the TN and TC regression approach, we found that ∼40–45 % of TC in the TSP samples during the pollen episodes was attributed to airborne pollens from Japanese cedar trees planted around tangerine farms in Jeju Island. The δ13C of citric acid in the airborne pollens (−26.3 ‰ collected at the Gosan site was similar to that in tangerine fruit (−27.4 ‰. The negative correlation between the citric acid-carbon/TC ratios and δ13CTC were obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollens and then transported to the Gosan site. Based on the thermal evolution pattern of organic aerosols during the carbon episodes, we found that organic aerosols originated from East China are more volatile on

  12. A Regional Stable Carbon Isotope Dendro-Climatology from the South African Summer Rainfall Area.

    Directory of Open Access Journals (Sweden)

    Stephan Woodborne

    Full Text Available Carbon isotope analysis of four baobab (Adansonia digitata L. trees from the Pafuri region of South Africa yielded a 1000-year proxy rainfall record. The Pafuri record age model was based on 17 radiocarbon dates, cross correlation of the climate record, and ring structures that were presumed to be annual for two of the trees. Here we present the analysis of five additional baobabs from the Mapungubwe region, approximately 200km west of Pafuri. The Mapungubwe chronology demonstrates that ring structures are not necessarily annually formed, and accordingly the Pafuri chronology is revised. Changes in intrinsic water-use efficiency indicate an active response by the trees to elevated atmospheric CO2, but this has little effect on the environmental signal. The revised Pafuri record, and the new Mapungubwe record correlate significantly with local rainfall. Both records confirm that the Medieval Warm Period was substantially wetter than present, and the Little Ice Age was the driest period in the last 1000 years. Although Mapungubwe is generally drier than Pafuri, both regions experience elevated rainfall peaking between AD 1570 and AD 1620 after which dry conditions persist in the Mapungubwe area until about AD 1840. Differences between the two records correlate with Agulhas Current sea-surface temperature variations suggesting east/west displacement of the temperate tropical trough system as an underlying mechanism. The Pafuri and Mapungubwe records are combined to provide a regional climate proxy record for the northern summer rainfall area of southern Africa.

  13. A Regional Stable Carbon Isotope Dendro-Climatology from the South African Summer Rainfall Area.

    Science.gov (United States)

    Woodborne, Stephan; Gandiwa, Patience; Hall, Grant; Patrut, Adrian; Finch, Jemma

    2016-01-01

    Carbon isotope analysis of four baobab (Adansonia digitata L.) trees from the Pafuri region of South Africa yielded a 1000-year proxy rainfall record. The Pafuri record age model was based on 17 radiocarbon dates, cross correlation of the climate record, and ring structures that were presumed to be annual for two of the trees. Here we present the analysis of five additional baobabs from the Mapungubwe region, approximately 200km west of Pafuri. The Mapungubwe chronology demonstrates that ring structures are not necessarily annually formed, and accordingly the Pafuri chronology is revised. Changes in intrinsic water-use efficiency indicate an active response by the trees to elevated atmospheric CO2, but this has little effect on the environmental signal. The revised Pafuri record, and the new Mapungubwe record correlate significantly with local rainfall. Both records confirm that the Medieval Warm Period was substantially wetter than present, and the Little Ice Age was the driest period in the last 1000 years. Although Mapungubwe is generally drier than Pafuri, both regions experience elevated rainfall peaking between AD 1570 and AD 1620 after which dry conditions persist in the Mapungubwe area until about AD 1840. Differences between the two records correlate with Agulhas Current sea-surface temperature variations suggesting east/west displacement of the temperate tropical trough system as an underlying mechanism. The Pafuri and Mapungubwe records are combined to provide a regional climate proxy record for the northern summer rainfall area of southern Africa. PMID:27427912

  14. Carbon stable isotope analysis as a tool for tracing temperature during the El Tremedal underground coal gasification at great depth

    Energy Technology Data Exchange (ETDEWEB)

    Brasseur, A.; Antenucci, D.; Bouquegneau, J.-M.; Coeme, A.; Dauby, P.; Letolle, R.; Mostade, M.; Pirlot, P.; Pirard, J.-P. [Universite de Liege, Liege (Belgium). Laboratoire de Genie Chimique, Institut de Chimie

    2002-01-01

    The new opportunity given by the underground gasifier developed at Alcorisa in Spain (Province of Teruel) in the framework of an European experiment has promoted a better understanding of gasification in a natural reactor. The thermodynamical equilibria of gasification reactions and the repartition of the stable isotopes of carbon ({sup 13}C/{sup 12}C) in the produced gases have been used to monitor the process. An estimation of the temperatures inside the gasifier and at the exhaust gas been performed. As shown by the isotopic balances, the tar formation is negligible or null and the pyrolysis zone spreads continuously. The study has confirmed the reality of the {sup 13}C isotopic abundance measurements for the system CO/CO{sub 2} as an indicator of the temperature inside the gasifier. During the gasifier expansion, the temperature at the exhaust decreases whereas the temperature inside the gasifier is practically constant showing a slight increasing trend. As pointed out by the data, the oxygen enrichment of the gasifying agent plays an important role on the estimated temperatures. 19 refs., 4 figs., 5 tabs.

  15. The traceability of animal meals in layer diets as detected by stable carbon and nitrogen isotope analyses of eggs

    Directory of Open Access Journals (Sweden)

    JC Denadai

    2008-09-01

    Full Text Available The aim of this study was to trace the inclusion of animal meals in layer diets by analyzing eggs and their fractions (yolk and albumen using the technique of carbon and nitrogen isotopes. Two-hundred and eighty-eight (288 73-week-old Shaver White layers, never fed animal ingredients, were randomly distributed in six treatments with six replicates each. The treatments were: control - corn and soybean meal based diet and five other experimental diets including bovine meat and bone meal (MBM; poultry offal meal (POM; feather meal (FM; feather meal and poultry offal meal (OFM, and poultry offal meal, feather meal, and meat and bone meal (MBOFM. The isotopic results were submitted to multivariate analysis of variance. Ellipses were determined through an error matrix (95% confidence to identify differences between treatments and the control group. In the albumen and yolk of all experimental treatments were significantly different from the control diet (p < 0.05. In summary, the stable isotope technique is able to trace the animal meals included in layer feeds in the final product under these experimental conditions.

  16. Reliability of stable carbon and oxygen isotope compositions of pedogenic needle fibre calcite as environmental indicators: examples from Western Europe.

    Science.gov (United States)

    Millière, Laure; Spangenberg, Jorge E; Bindschedler, Saskia; Cailleau, Guillaume; Verrecchia, Eric P

    2011-09-01

    Stable carbon and oxygen isotope analyses were conducted on pedogenic needle fibre calcite (NFC) from seven sites in areas with roughly similar temperate climates in Western Europe, including the Swiss Jura Mountains, eastern and southern France, northern Wales, and north-eastern Spain. The δ(13)C values (-12.5 to-6.8 ‰ Vienna Pee Dee Belemnite (VPDB)) record the predominant C(3) vegetation cover at the sites. A good correlation was found between mean monthly climatic parameters (air temperature, number of frost days, humidity, and precipitation) and δ(18)O values (-7.8 to-3.4‰ VPDB) of all the NFC. Similar seasonal variations of δ(18)O values for monthly NFC samples from the Swiss sites and those of mean monthly δ(18)O values of local precipitation and meteorological data point out precipitation and preferential growth/or recrystallisation of the pedogenic needle calcite during dry seasons. These covariations indicate the potential of stable isotope compositions of preserved NFC in fossil soil horizons as a promising tool for palaeoenvironmental reconstructions.

  17. RNA-stable-isotope probing shows utilization of carbon from inulin by specific bacterial populations in the rat large bowel.

    Science.gov (United States)

    Tannock, Gerald W; Lawley, Blair; Munro, Karen; Sims, Ian M; Lee, Julian; Butts, Christine A; Roy, Nicole

    2014-04-01

    Knowledge of the trophisms that underpin bowel microbiota composition is required in order to understand its complex phylogeny and function. Stable-isotope ((13)C)-labeled inulin was added to the diet of rats on a single occasion in order to detect utilization of inulin-derived substrates by particular members of the cecal microbiota. Cecal digesta from Fibruline-inulin-fed rats was collected prior to (0 h) and at 6, 12, 18 and 24 h following provision of the [(13)C]inulin diet. RNA was extracted from these cecal specimens and fractionated in isopycnic buoyant density gradients in order to detect (13)C-labeled nucleic acid originating in bacterial cells that had metabolized the labeled dietary constituent. RNA extracted from specimens collected after provision of the labeled diet was more dense than 0-h RNA. Sequencing of 16S rRNA genes amplified from cDNA obtained from these fractions showed that Bacteroides uniformis, Blautia glucerasea, Clostridium indolis, and Bifidobacterium animalis were the main users of the (13)C-labeled substrate. Culture-based studies of strains of these bacterial species enabled trophisms associated with inulin and its hydrolysis products to be identified. B. uniformis utilized Fibruline-inulin for growth, whereas the other species used fructo-oligosaccharide and monosaccharides. Thus, RNA-stable-isotope probing (RNA-SIP) provided new information about the use of carbon from inulin in microbiota metabolism.

  18. Pharmaceuticals labelled with stable isotopes

    International Nuclear Information System (INIS)

    The relatively new field of pharmaceuticals labelled with stable isotopes is reviewed. Scientific, juridical, and ethical questions are discussed concerning the application of these pharmaceuticals in human medicine. 13C, 15N, and 2H are the stable isotopes mainly utilized in metabolic function tests. Methodical contributions are given to the application of 2H, 13C, and 15N pharmaceuticals showing new aspects and different states of development in the field under discussion. (author)

  19. Evaluation of the newly proposed vitamin A supplementation regimen for postpartum mothers using stable carbon isotopes

    International Nuclear Information System (INIS)

    The long-term goal of this project is to establish public health programs to improve the health of women and children globally by determining safe and effective methods to improve vitamin A status. By improving the vitamin A status of mothers and infants, mortality and morbidity of children will be reduced. The specific aims of this proposal are: - To determine the length of time mothers are protected against depletion after receiving either 400,000 IU of vitamin A in two doses of 200,000 IU 24 hours apart or one dose of 200,000 IU. The modified relative dose response (MRDR) test will be used at monthly intervals for 5 months post dosing to assess changes in vitamin A status. - To determine the degree of dilution in the vitamin A body pool after dosing women with either 200,000 or 400,000 IU of vitamin A using stable 13C2-retinol as a tracer. - To determine the difference in total vitamin A body reserves of women who received either 200,000 or 400,000 IU of vitamin A using the 13C2-retinol isotope dilution (13C2-RID) test. This proposal addresses the following hypothesis: In women who are given 400,000 IU of vitamin A, the length of protection from vitamin A depletion is increased but not doubled. A 400,000 IU dose dilutes the vitamin A pool more than 200,000 IU but not by 2:1 and a 400,000 IU dose increases the total body reserves of vitamin A over 200,000 IU but not by 2:1. (author)

  20. Stable carbon isotope discrimination and microbiology of methane formation in tropical anoxic lake sediments

    Directory of Open Access Journals (Sweden)

    R. Conrad

    2010-11-01

    Full Text Available Methane is an important end product of degradation of organic matter in anoxic lake sediments. Methane is mainly produced by either reduction of CO2 or cleavage of acetate involving different methanogenic archaea. The contribution of the different methanogenic paths and of the diverse bacteria and archaea involved in CH4 production exhibits a large variability that is not well understood. Lakes in tropical areas, e.g. in Brazil, are wetlands with high potential impact on the global CH4 budget. However, they have hardly been studied with respect to methanogenesis. Therefore, we used samples from 16 different lake sediments in the Pantanal and Amazon region of Brazil to measure production of CH4, CO2, analyze the content of 13C in the products and in intermediately formed acetate, determine the abundance of bacterial and archaeal microorgansisms and their community composition and diversity by targeting the genes of bacterial and archaeal ribosomal RNA and of methyl coenzyme M reductase, the key enzyme of methanogenic archaea. These experiments were done in the presence and absence of methyl fluoride, an inhibitor of acetoclastic methanogenesis. While production rates of CH4 and CO2 were correlated to the content of organic matter and the abundance of archaea in the sediment, values of 13C in acetate and CH4 were related to the 13C content of organic matter and to the path of CH4 production with its intrinsic carbon isotope fractionation. Isotope fractionation was small (average 10‰ for conversion of Corg to acetate-methyl, which was hardly further fractionated during CH4 production. However, fractionation was strong for CO2 conversion to CH4 (average 75‰, which generally accounted for >50% of total CH4 production. Canonical correspondence analysis did not

  1. Stable carbon isotope discrimination and microbiology of methane formation in tropical anoxic lake sediments

    Directory of Open Access Journals (Sweden)

    R. Conrad

    2011-03-01

    Full Text Available Methane is an important end product of degradation of organic matter in anoxic lake sediments. Methane is mainly produced by either reduction of CO2 or cleavage of acetate involving different methanogenic archaea. The contribution of the different methanogenic paths and of the diverse bacteria and archaea involved in CH4 production exhibits a large variability that is not well understood. Lakes in tropical areas, e.g. in Brazil, are wetlands with high potential impact on the global CH4 budget. However, they have hardly been studied with respect to methanogenesis. Therefore, we used samples from 16 different lake sediments in the Pantanal and Amazon region of Brazil to measure production of CH4, CO2, analyze the content of 13C in the products and in intermediately formed acetate, determine the abundance of bacterial and archaeal microorgansisms and their community composition and diversity by targeting the genes of bacterial and archaeal ribosomal RNA and of methyl coenzyme M reductase, the key enzyme of methanogenic archaea. These experiments were done in the presence and absence of methyl fluoride, an inhibitor of acetoclastic methanogenesis. While production rates of CH4 and CO2 were correlated to the content of organic matter and the abundance of archaea in the sediment, values of 13C in acetate, CO2, and CH4 were related to the 13C content of organic matter and to the path of CH4 production with its intrinsic carbon isotope fractionation. Isotope fractionation was small (average 10‰ for conversion of Corg to acetate-methyl, which was hardly further fractionated during CH4 production. However, fractionation was strong for CO2 conversion to CH4 (average 75‰, which generally accounted for >50% of total CH4 production. Canonical correspondence

  2. Intra-annual variability of carbon and nitrogen stable isotopes in suspended organic matter in waters of the western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Maya, M.V.; Karapurkar, S.G.; Naik, H.; Roy, R.; Shenoy, D.M.; Naqvi, S.W.A.

    and later air dried in a clean laminar flow to remove all traces of acid fumes. Elemental and isotopic measure- ments were made on single filters. Two to three aliquots of 12 mm diameter were sub-sectioned from the filter paper and packed tightly in tin cups... for analysis of isotopic ratios. Stable carbon and nitrogen isotope ratios were measured us- ing a Thermo Finnigan DELTA V plus isotope ratio mass spectrometer in continuous-flow mode after high tempera- ture flash combustion at 1050 ◦C in a EURO3000 Eurovector...

  3. Stable carbon and oxygen isotope investigation in historical lime mortar and plaster - Results from field and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Kosednar-Legenstein, B. [Institute of Applied Geosciences, Graz University of Technology, Rechbauerstrasse 12, A-8010 Graz (Austria); Dietzel, M. [Institute of Applied Geosciences, Graz University of Technology, Rechbauerstrasse 12, A-8010 Graz (Austria)], E-mail: martin.dietzel@tugraz.at; Leis, A. [Institute of Water Resources Management, Hydrogeology and Geophysics, Joanneum Research, Elisabethstrasse 16/II, A-8010 Graz (Austria); Stingl, K. [Institute of Applied Geosciences, Graz University of Technology, Rechbauerstrasse 12, A-8010 Graz (Austria)

    2008-08-15

    Lime mortar and plaster were sampled from Roman, medieval and early modern buildings in Styria. The historical lime mortar and plaster consist of calcite formed in the matrix during setting and various aggregates. The stable C and O isotopic composition of the calcite matrix was analyzed to get knowledge about the environmental conditions during calcite formation. The {delta}{sup 13}C{sub matrix} and {delta}{sup 18}O{sub matrix} values range from -31 to 0 per mille and -26 to -3 per mille (VPDB), respectively. Obviously, such a range of isotope values does not represent the local natural limestone assumed to be used for producing the mortar and plaster. In an ideal case, the calcite matrix in lime mortar and plaster is isotopically lighter in the exterior vs. the interior mortar layer according to the relationship {delta}{sup 18}O{sub matrix} = 0.61 . {delta}{sup 13}C{sub matrix} - 3.3 (VPDB). Calcite precipitation by uptake of gaseous CO{sub 2} into alkaline Ca(OH){sub 2} solutions shows a similar relationship, {delta}{sup 18}O{sub calcite} = 0.67 . {delta}{sup 13}C{sub calcite} - 6.4 (VPDB). Both relationships indicate that the {sup 13}C/{sup 12}C and {sup 18}O/{sup 16}O values of the calcite reflect the setting behaviour of the lime mortar and plaster. Initially, CO{sub 2} from the atmosphere is fixed as calcite, which is accompanied by kinetic isotope fractionation mostly due to the hydroxylation of CO{sub 2} ({delta}{sup 13}C{sub matrix} {approx} -25 per mille and {delta}{sup 18}O{sub matrix} {approx} -20 per mille ). As calcite formation continued the remaining gaseous CO{sub 2} is subsequently enriched in {sup 13}C and {sup 18}O causing later formed calcite to be isotopically heavier along the setting path in the matrix. Deviations from such an ideal isotopic behaviour may be due to the evolution of H{sub 2}O, e.g. evaporation, the source of CO{sub 2}, e.g. from biogenic origin, relicts of the natural limestone, and secondary effects, such as

  4. In-situ studies of microbial CH4 oxidation efficiency in Arctic wetland soils. Applications of stable carbon isotopes

    International Nuclear Information System (INIS)

    Arctic wetland soils are significant sources of the climate-relevant trace gas methane (CH4). The observed accelerated warming of the Arctic is expected to cause deeper permafrost thawing followed by increased carbon mineralization and CH4 formation in water-saturated permafrost-affected tundra soils thus creating a positive feedback to climate change. Aerobic CH4 oxidation is regarded as the key process reducing CH4 emissions from wetlands, but quantification of turnover rates has remained difficult so far. This study improved the in-situ quantification of microbial CH4 oxidation efficiency in arctic wetland soils in Russia's Lena River Delta based on stable isotope signatures of CH4. In addition to the common practice of determining the stable isotope fractionation during oxidation, additionally the fractionation effect of diffusion, an important gas transport mechanism in tundra soils, was investigated for both saturated and unsaturated conditions. The isotopic fractionation factors αox and αdiff were used to calculate the CH4 oxidation efficiency from the CH4 stable isotope signatures of wet polygonal tundra soils of different hydrology. Further, the method was used to study the short-term effects of temperature increase with a climate manipulation experiment. For the first time, the stable isotope fractionation of CH4 diffusion through water-saturated soils was determined with αdiff = 1.001 ± 0.0002 (n = 3). CH4 stable isotope fractionation during diffusion through air-filled pores of the investigated polygonal tundra soils was αdiff = 1.013 ± 0.003 (n = 18). For the studied sites the fractionation factor for diffusion under saturated conditions αdiff = 1.001 seems to be of utmost importance for the quantification of the CH4 oxidation efficiency, since most of the CH4 is oxidized in the saturated part at the aerobic-anaerobic interface. Furthermore, it was found that αox differs widely between sites and horizons (mean αox = 1.018 ± 0.009) and needs

  5. Stable carbon isotope evidence for tracing the diet of the host Hepialus larva of Cordyceps sinensis in the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    CHEN Di; YUAN JianPing; XU ShiPing; ZHOU XiaoGang; ZHANG Yan; XU XiaoMing; ZOU ZhiWen; ZHANG GuRen; WANG JiangHai

    2009-01-01

    Two types of Hepialus larvae with different diets were distinguished in the Sejila Mountain, Tibetan Plateau based on the stable carbon isotope data of the host Hepialus larva of Cordyceps sinensis and its closely adjacent tender plant roots and humus fractions. Type I is the larva chiefly fed by soil humus, and characterized by the δ13C values of -22.6‰ to -23.4‰, and more than -23.4‰ in its heads. Type Ⅱ is the larva chiefly fed by tender plant roots, and characterized by the δ13C values of -24.6‰ to -27.6‰, and less than -24.6‰, in its heads. Our result has exceeded the traditional understanding that their food sources only come from the tender plant roots, and may provide evidence for choosing cheap and high-quality foods and further establishing artificial habitats in their large-scale reproduction.

  6. Effects of pretreatment procedures on fatty acid composition and stable carbon isotopes in the marine microalgaIsochrysis zhanjiangenisis

    Institute of Scientific and Technical Information of China (English)

    YAO Jingyuan; LIU Yu; LI Ying; WANG Haixia

    2016-01-01

    This study aims to quantify the effects of different pretreatment methods on the stable carbon isotope values of fatty acids in marine microalgae (Isochrysis zhanjiangenisis). To identify the effects of sample preparation on theδ13C value and the fatty acid composition, we examined eight types of pretreatment methods including: (a) drying the sample followed by direct methyl esterification using HCl-CH3OH; (b) drying the sample followed by direct methyl esterification using H2SO4-CH3OH; (c) drying the sample by ultrasonic extraction and methyl-esterification using HCl-CH3OH; (d) drying the sample by ultrasonic extraction and methyl-esterification using H2SO4-CH3OH; (e) fresh sample followed by direct methyl-esterification using HCl-CH3OH; (f) fresh sample followed by direct methyl-esterification using H2SO4-CH3OH; (g) fresh sample with ultrasonic extraction followed by methyl-esterification using HCl-CH3OH, and (h) fresh sample with ultrasonic extraction followed by methyl-esterification using H2SO4-CH3OH. The results show that theδ13C values from Groups a–e, g and h fluctuated within 0.3‰, and theδ13C values of Group f were approximately 0.7‰ lower than the other seven groups. Therefore, the different sample pretreatment methods used towards the extraction of fatty acids from marine microalgae may result in different results regarding the stable carbon isotope ratios, and if necessary a correction should be applied.

  7. The impact of recycling of organic carbon on the stable carbon isotopic composition of dissolved inorganic carbon in a stratified marine system (Kyllaren fjord, Norway)

    NARCIS (Netherlands)

    Breugel, Y. van; Schouten, S.; Paetzel, M.; Nordeide, R.; Sinninghe Damsté, J.S.

    2005-01-01

    A negative carbon isotope shift in sedimentary organic carbon deposited in stratified marine and lacustrine systems has often been inferred to be a consequence of the process of recycling of respired and, therefore, 13C-depleted, dissolved inorganic carbon (DIC) formed from mineralization of descend

  8. Quantitative microbial ecology through stable isotope probing.

    Science.gov (United States)

    Hungate, Bruce A; Mau, Rebecca L; Schwartz, Egbert; Caporaso, J Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J; Liu, Cindy M; McHugh, Theresa A; Marks, Jane C; Morrissey, Ember M; Price, Lance B

    2015-11-01

    Bacteria grow and transform elements at different rates, and as yet, quantifying this variation in the environment is difficult. Determining isotope enrichment with fine taxonomic resolution after exposure to isotope tracers could help, but there are few suitable techniques. We propose a modification to stable isotope probing (SIP) that enables the isotopic composition of DNA from individual bacterial taxa after exposure to isotope tracers to be determined. In our modification, after isopycnic centrifugation, DNA is collected in multiple density fractions, and each fraction is sequenced separately. Taxon-specific density curves are produced for labeled and nonlabeled treatments, from which the shift in density for each individual taxon in response to isotope labeling is calculated. Expressing each taxon's density shift relative to that taxon's density measured without isotope enrichment accounts for the influence of nucleic acid composition on density and isolates the influence of isotope tracer assimilation. The shift in density translates quantitatively to isotopic enrichment. Because this revision to SIP allows quantitative measurements of isotope enrichment, we propose to call it quantitative stable isotope probing (qSIP). We demonstrated qSIP using soil incubations, in which soil bacteria exhibited strong taxonomic variations in (18)O and (13)C composition after exposure to [(18)O]water or [(13)C]glucose. The addition of glucose increased the assimilation of (18)O into DNA from [(18)O]water. However, the increase in (18)O assimilation was greater than expected based on utilization of glucose-derived carbon alone, because the addition of glucose indirectly stimulated bacteria to utilize other substrates for growth. This example illustrates the benefit of a quantitative approach to stable isotope probing.

  9. Oil-source correlation of the pre-Tertiary in the Huanghua Depression: Insights from stable carbon isotopes and molecular markers

    Institute of Scientific and Technical Information of China (English)

    YANG Yongcai; ZHANG Zhihuan; LI Wei; QIN Liming; FANG Chaohe; LIN Yuxiang; LIU Hua

    2008-01-01

    Stable carbon isotopes were used together with molecular markers to constrain genetic relationships between sandstone extracts and potential source rocks in the pre-Tertiary in the Huanghua Depression, North China.Comparison of the extracts from Permo-Carboniferous terrigenous mudstones and Ordovician marine carbonates indicated that their prominent differences are in stable carbon isotopes, molecular markers and thermal maturity.Although the extracts of the Mesozoic and Lower Permian Xiashihezi Formation sandstones have some similar isotopic characteristics, molecular markers data provide a good correlation between the Upper Jurassic-Lower Cretaceous oils and the Upper Carboniferous Taiyuan Formation mudstones, and between the Lower Permian Xiashihezi Formation oils and the Lower Permian mudstones. The results showed that the Upper Jurassic-Lower Cretaceous sandstone oils were derived chiefly from the Upper Carboniferous Taiyuan Formation terrigenous mudstones and that the Lower Permian Xiashihezi Formation oils were sourced from the Lower Permian Shanxi Formation and Xiashihezi Formation terdgenous mudstones.

  10. Using stable isotope techniques to investigate carbon cycle dynamics of an agricultural ecosystem

    Science.gov (United States)

    Zhang, Jianmin

    2007-12-01

    In this study, continuous measurements of the mixing ratios of 12CO2 and 13CO2 with tunable diode laser (TDL) absorption spectroscopy were combined with micrometeorological observations to partition the net ecosystem CO2 exchange into photosynthesis and respiration for a corn-soybean rotation ecosystem. The dynamics of the canopy-scale isotope discrimination (DeltaA), isotope ratios of ecosystem respiration and net ecosystem CO2 exchange (delta R and deltaN), and isoflux were examined using both TDL data and a multilayer canopy model. Compared with the nighttime regression method and the multilayer model results, the isotopic flux partitioning method showed greater short-term variations. Uncertainty in the partitioning was closely related to the isotopic disequilibrium between ecosystem respiration and photosynthesis. The partitioning uncertainty was smaller for the early growing season when the isotopic disequilibrium was larger. Uncertainties in the deltaN and deltaR estimates accounted for the most of the overall partitioning uncertainty. Nightly deltaR estimated from the flux-ratio approach showed significant seasonal variation (-32‰ to -11‰), corresponding closely with canopy phenology. The multilayer model results also showed apparent diurnal deltaR variation associated with changes in the contributions of component respiration. Daytime deltaR may differ by up to 2‰ from nighttime values over the diurnal period. The extrapolation of nighttime deltaR to daytime values presented a potential limitation in the isotopic approach. The multilayer modeled isotope discrimination showed significant vertical variations within the canopy resulting from light variations and the different response to the change of ambient CO2 for sunlit and shaded leaves. The modeled values also showed pronounced diurnal changes from 3.7‰ to 4.5‰ in correspondence with the onset and cessation of photosynthesis. However, the isotopic partitioning yielded relatively constant

  11. Marine subsidies of island communities in the Gulf of California: evidence from stable carbon and nitrogen isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, W.B.; Polis, G.A. [Vanderbilt Univ., Dept. of Biology, Nashville, TN (United States)

    1998-02-01

    Coastal sites support larger (2 to > 100 x) populations of many consumers than inland sites on islands in the Gulf of California. Previous data suggested that subsidies of energy and nutrients from the ocean allowed large coastal populations. Stable carbon and nitrogen isotopes are frequently used to analyse diet composition of organisms: they are particularly useful to distinguish between diet sources with distinct isotopic signatures, such as marine and terrestrial diets. We analyzed the {sup 13}C and {sup 15}N concentrations of coastal versus inland spiders and scorpions to test the hypothesis that coastal individuals exhibited more strongly marine-based diets than inland individuals. Coastal spiders and scorpions were significantly more enriched in {sup 13}C and {sup 15}N than inland spiders and scorpions, suggesting that the coastal individuals consumed more marine-based foods than their inland counterparts. These patterns existed in both drought years and wet El Nino years. However, the marine influence was stronger in drought years when terrestrial productivity was nearly non-existent, than in wet years when terrestrial productivity increased by an order of magnitude. (au). 26 refs.

  12. Hydrogen and Carbon Stable Isotopic Compositions and Concentrations of Methane in Cave Air of Cueva de Villa Luz, Tabasco, Mexico

    Science.gov (United States)

    Webster, K.; Rosales Lagarde, L.; Sauer, P. E.; Schimmelmann, A.; Lennon, J. T.; Boston, P. J.

    2014-12-01

    Cueva de Villa Luz (CVL) is a unique biogeochemical environment where microbial consortia are supported by hydrogen sulfide (H2S) leading to sulfuric acid speleogenesis (SAS) which is thought to have generated the porosity and permeability of several petroleum reservoirs. Possible sources of the sulfur (S) include the Chichón Volcano and petroleum basins in the area. A better understanding of the source of the H2S in CVL may help predict where else SAS may have occurred. Analysis of methane (CH4) in CVL may provide a proxy to assess the source of S entering CVL. We obtained 13 air samples in 1-L Tedlar® bags from varying locations in CVL to assess the role of CH4 in sulfide-rich karst systems. CH4 and carbon dioxide (CO2) concentrations were measured by gas-chromatography. The stable isotopic ratios of carbon and hydrogen were measured on a stable isotope-ratio mass-spectrometer. CH4 in the air of CVL ranged from 1.88 ± 0.10 ppmv to 3.7 ± 0.2 ppmv. CO2 concentrations ranged from 400 ± 20 ppmv to 920 ± 50 ppmv. For comparison, the CH4 and CO2 concentrations in the outside atmosphere were 1.96 ± 0.10 ppmv and 430 ± 20 ppmv respectively. CH4 and CO2 were positively correlated in CVL (R2 = 0.91, CH4 = [0.0035 ± 0.0007] CO2 + [0.4 ± 0.4], p >0.01). The highest concentrations were near springs. Keeling-style analysis showed that the CH4 samples from CVL plot along a two-end member mixing model and suggest that CH4 is outgassing from spring water with isotopic compositions δ13CCH4 = -24 ± 3 ‰ and δ2HCH4 = -40 ± 40 ‰. CO2 did not plot along a two end member mixing model. The proposed δ13C of CH4 entering from springs does not closely match the δ13CCH4 values from hydrocarbon basins in the area. This is likely due to oxidative loss of CH4 as it ascends to CVL which may be partly driven by anaerobic methanotrophy coupled to sulfate reduction. Analysis of the spring water chemistry coupled to biogeochemical modeling may help quantify the amount of

  13. Trophic structure of mesopelagic fishes in the western Mediterranean based on stable isotopes of carbon and nitrogen

    Science.gov (United States)

    Valls, M.; Olivar, M. P.; Fernández de Puelles, M. L.; Molí, B.; Bernal, A.; Sweeting, C. J.

    2014-10-01

    Mesopelagic fishes play an important role in the transfer of organic material in the photic zone to depth although the trophodynamic partitioning amongst co-existing and presumably competing species is unclear. This study employs combined carbon and nitrogen stable isotope analyses (δ13C and δ15N) of the 18 most abundant western Mediterranean mesopelagic fishes to explore niche partitioning in this group. Sampling was conducted along the water column from the shelf and slope grounds of the Balearic Islands in two contrasting periods (late autumn and summer). Trophodynamics were explored at assemblage level and at inter- and intra-species resolutions respectively using Bayesian diet mixing models and size specific behaviour respectively. Seasonal δ13C differences in near basal particulate organic matter (POM) and zooplankton fractions were almost directly replicated in higher fauna suggesting strong isotopic coupling between mesopelagic fishes and planktonic production. Despite reliance on similar basal production, species were segregated by trophic position with a graduation from 2.9 for the small Gonostomatidae Cyclothone braueri to 4.0 for the Myctophidae Lobianchia dofleini. Mixing model data reflected basic trophic position estimates with higher contributions of small fish and zooplankton/POM in higher and lower trophic level species respectively. Species could be categorized as showing preference for i) mesozooplankton/POM as for C. braueri, (in the lower TrL), ii) euphausiids and fish prey as for L. dofleini and the near bottom Lampanyctus crocodilus (in the upper TrL) and iii) mesozooplankton/euphausiids as Ceratoscopelus maderensis, Lampanyctus pusillus or the migrating L. crocodilus. There was little evidence of size based inter-population trophodynamics, with size-isotope trends explained by co-varying lipid content.

  14. Formation of carbonate concretions in surface sediments of two mud mounds, offshore Costa Rica: a stable isotope study

    Science.gov (United States)

    Mavromatis, Vasileios; Botz, Reiner; Schmidt, Mark; Liebetrau, Volker; Hensen, Christian

    2014-10-01

    The surface sediments of two mud mounds ("Mound 11" and "Mound 12") offshore southwest Costa Rica contain abundant authigenic carbonate concretions dominated by high-Mg calcite (14-20 mol-% MgCO3). Pore fluid geochemical profiles (sulfate, sulfide, methane, alkalinity, Ca and Mg) indicate recent carbonate precipitation within the zone of anaerobic oxidation of methane (AOM) at variable depths. The current location of the authigenic carbonate concretions is, however, not related to the present location of the AOM zone, suggesting mineral precipitation under past geochemical conditions as well as changes in the flow rates of upward migrating fluids. Stable oxygen and carbon isotope analysis of authigenic carbonate concretions yielded δ18Ocarbonate values ranging between 34.0 and 37.7 ‰ Vienna standard mean ocean water (VSMOW) and δ13Ccarbonate values from -52.2 to -14.2 ‰ Vienna Pee Dee belemnite (VPDB). Assuming that no temperature changes occurred during mineral formation, the authigenic carbonate concretions have been formed at in situ temperature of 4-5 °C. The δ18Ocarbonate values suggest mineral formation from seawater-derived pore fluid (δ18Oporefluid = 0 ‰ VSMOW) for Mound 12 carbonate concretions but also the presence of an emanating diagenetic fluid (δ18Oporefluid ≈5 ‰) in Mound 11. A positive correlation between δ13Ccarbonate and δ18Ocarbonate is observed, indicating the admixing of two different sources of dissolved carbon and oxygen in the sediments of the two mounds. The carbon of these sources are (1) marine bicarbonate (δ13Cporefluid ≈0 ‰) and (2) bicarbonate which formed during the AOM (δ13Cporefluid ≈-70 ‰). Furthermore, the δ18Oporefluid composition, with values up to +4.7 ‰ Vienna standard mean ocean water (VSMOW), is interpreted to be affected by the presence of emanating, freshened and boron-enriched fluids. Earlier, it has been shown that the origin of 18O-enriched fluids are deep diagenetic processes as it was

  15. Stable isotope production with laser techniques; Production d`isotopes stables a l`aide des techniques laser

    Energy Technology Data Exchange (ETDEWEB)

    Petit, A. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Procedes d`Enrichissement

    1994-12-31

    Laser properties may be used for stable isotope production either by selective photoionization of an atom particular isotope, either by selective photodissociation of a molecule. Principles of both processes are reviewed and examples of calcium 43 isotope separation through photoionization and of carbon and oxygen isotope separation by photodissociation are presented. 4 figs., 1 tab., 11 refs.

  16. Recognition of n-alkyl and isoprenoid biopolymers in marine sediments by stable carbon isotopic analysis of pyrolysis products of kerogens

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Hold, I.M.; Schouten, S.; Kaam-Peters, H.M.E. van

    1998-01-01

    Analysis of the pyrolysis products of several marine kerogens revealed that the stable carbon isotopic composition of the n-alkanes (C10-C25) are quite similar to those of the n-alkenes. This suggests that they have a common origin such as algal biopolymers. The isoprenoid alkanes (C13-C20) also hav

  17. Spatial variability of carbon (δ13C) 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...

  18. Stable isotopic investigations of early development in extant and fossil chambered cephalopods I. Oxygen isotopic composition of eggwater and carbon isotopic composition of siphuncle organic matter in Nautilus

    Science.gov (United States)

    Crocker, Kimberley C.; DeNiro, Michael J.; Ward, Peter D.

    1985-12-01

    Eggwaters from the chambered cephalopod Nautilus are depleted in both 18O and deuterium relative to ambient seawater. Eggwaters from six other species, including the related chambered cephalopod Sepia, do not show such depletion. These observations indicate that the previously observed step towards more positive δ 18O values in calcium carbonate laid down after Nautilus hatches, relative to carbonate precipitated prior to hatching, can be explained by equilibration of the carbonate with water in the egg before hatching and with seawater after hatching. The presence of an oxygen isotope difference between eggwater and seawater for Nautilus and its absence for Sepia suggest that hatching will be recorded in the δ 18O values of shell carbonates for some but not all extinct and extant chambered cephalopods. The δ 13C values of the organic fraction of the siphuncle in Nautilus do not show any consistent pattern with regard to the time of formation before or after hatching. This observation suggests that the minimum in δ 13C values previously observed for calcium carbonate precipitated after Nautilus hatches is not caused by a change in food sources once the animal becomes free-swimming, as has been suggested.

  19. Stable isotopes in Lithuanian bioarcheological material

    Science.gov (United States)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

    Investigation of bioarcheological material of ancient human populations allows us to understand the subsistence behavior associated with various adaptations to the environment. Feeding habits are essential to the survival and growth of ancient populations. Stable isotope analysis is accepted tool in paleodiet (Schutkowski et al, 1999) and paleoenvironmental (Zernitskaya et al, 2014) studies. However, stable isotopes can be useful not only in investigating human feeding habits but also in describing social and cultural structure of the past populations (Le Huray and Schutkowski, 2005). Only few stable isotope investigations have been performed before in Lithuanian region suggesting a quite uniform diet between males and females and protein intake from freshwater fish and animal protein. Previously, stable isotope analysis has only been used to study a Stone Age population however, more recently studies have been conducted on Iron Age and Late medieval samples (Jacobs et al, 2009). Anyway, there was a need for more precise examination. Stable isotope analysis were performed on human bone collagen and apatite samples in this study. Data represented various ages (from 5-7th cent. to 18th cent.). Stable carbon and nitrogen isotope analysis on medieval populations indicated that individuals in studied sites in Lithuania were almost exclusively consuming C3 plants, C3 fed terrestrial animals, and some freshwater resources. Current investigation demonstrated social differences between elites and country people and is promising in paleodietary and daily life reconstruction. Acknowledgement I thank prof. dr. G. Grupe, Director of the Anthropological and Palaeoanatomical State Collection in Munich for providing the opportunity to work in her laboratory. The part of this work was funded by DAAD. Antanaitis-Jacobs, Indre, et al. "Diet in early Lithuanian prehistory and the new stable isotope evidence." Archaeologia Baltica 12 (2009): 12-30. Le Huray, Jonathan D., and Holger

  20. Long-term fertilization alters chemically-separated soil organic carbon pools: Based on stable C isotope analyses

    Science.gov (United States)

    Dou, Xiaolin; He, Ping; Cheng, Xiaoli; Zhou, Wei

    2016-01-01

    Quantification of dynamics of soil organic carbon (SOC) pools under the influence of long-term fertilization is essential for predicting carbon (C) sequestration. We combined soil chemical fractionation with stable C isotope analyses to investigate the C dynamics of the various SOC pools after 25 years of fertilization. Five types of soil samples (0-20, 20-40 cm) including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, IN; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into recalcitrant and labile fractions, and the fractions were analysed for C content, C:N ratios, δ13C values, soil C and N recalcitrance indexes (RIC and RIN). Chemical fractionation showed long-term MNPK fertilization strongly increased the SOC storage in both soil layers (0-20 cm = 1492.4 gC m2 and 20-40 cm = 1770.6 gC m2) because of enhanced recalcitrant C (RC) and labile C (LC). The 25 years of inorganic fertilizer treatment did not increase the SOC storage mainly because of the offsetting effects of enhanced RC and decreased LC, whereas no clear SOC increases under the SNPK fertilization resulted from the fast decay rates of soil C.

  1. Stable isotopic compositions of elemental carbon in PM1.1 in north suburb of Nanjing Region, China

    Science.gov (United States)

    Guo, Zhaobing; Jiang, Wenjuan; Chen, Shanli; Sun, Deling; Shi, Lei; Zeng, Gang; Rui, Maoling

    2016-02-01

    Stable isotopic compositions (δ13C) of elemental carbon (EC) in PM1.1 in north suburb of Nanjing region were determined in order to quantitatively evaluate the carbon sources of atmospheric fine particles during different seasons. Besides, δ13C values from potential sources such as coal combustion, vehicle exhaust, biomass burning, and dust were synchronously measured. The results showed that the average δ13C values of EC in PM1.1 in winter and summer were - 23.89 ± 1.6‰ and - 24.76 ± 0.9‰, respectively. Comparing with δ13C values from potential sources, we concluded that the main sources of EC in PM1.1 were from the emission of coal combustion and vehicle exhaust. The higher δ13C values in winter than those in summer were chiefly attributed to the more coal consumption. Combining with the concentrations of SO42 - and K+ in PM1.1, the high δ13C values of EC on 24 December and 27 December 2013 were ascribed to extra input of corn straw burning in addition to coal combustion and vehicle exhaust.

  2. Long-term fertilization alters chemically-separated soil organic carbon pools: Based on stable C isotope analyses.

    Science.gov (United States)

    Dou, Xiaolin; He, Ping; Cheng, Xiaoli; Zhou, Wei

    2016-01-01

    Quantification of dynamics of soil organic carbon (SOC) pools under the influence of long-term fertilization is essential for predicting carbon (C) sequestration. We combined soil chemical fractionation with stable C isotope analyses to investigate the C dynamics of the various SOC pools after 25 years of fertilization. Five types of soil samples (0-20, 20-40 cm) including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, IN; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into recalcitrant and labile fractions, and the fractions were analysed for C content, C:N ratios, δ(13)C values, soil C and N recalcitrance indexes (RIC and RIN). Chemical fractionation showed long-term MNPK fertilization strongly increased the SOC storage in both soil layers (0-20 cm = 1492.4 gC m(2) and 20-40 cm = 1770.6 gC m(2)) because of enhanced recalcitrant C (RC) and labile C (LC). The 25 years of inorganic fertilizer treatment did not increase the SOC storage mainly because of the offsetting effects of enhanced RC and decreased LC, whereas no clear SOC increases under the SNPK fertilization resulted from the fast decay rates of soil C.

  3. Molecular distributions and compound-specific stable carbon isotopic compositions of lipids in wintertime aerosols from Beijing.

    Science.gov (United States)

    Ren, Lujie; Fu, Pingqing; He, Yue; Hou, Juzhi; Chen, Jing; Pavuluri, Chandra Mouli; Sun, Yele; Wang, Zifa

    2016-01-01

    Molecular distributions and stable carbon isotopic compositions (δ(13)C) of n-alkanes, fatty acids and n-alcohols were investigated in urban aerosols from Beijing, northern China to better understand the sources and long-range atmospheric transport of terrestrial organic matter during polluted and clear days in winter. n-Alkanes (C19-C36), fatty acids (C8-C32) and n-alcohols (C16-C32) detected in Beijing aerosols are characterized by the predominance of C23, C16 and C28, respectively. Carbon preference index (CPI) values of n-alkanes, the ratios of the sum of odd-numbered n-alkanes to the sum of even-numbered n-alkanes, are close to 1, indicating a heavy influence of fossil fuel combustion. Relatively higher ratios of C(18:0+16:0)/C(18:n+16:1) (fatty acids) on clear days than polluted days indicate that long-distance transport and/or photochemical aging are more significant during clear days. δ(13)C values of n-alkanes and low molecular weight fatty acids (C16:0, C18:0) ranged from -34.1 to -24.7% and -26.9 to -24.6%, respectively, which are generally heavier on polluted days than those on clear days. Such a wide range suggests that atmospheric lipids in Beijing aerosols originate from multiple sources and encounter complicated atmospheric processes during long-range transport in North China. PMID:27270951

  4. Biochemical and stable carbon isotope records of mangrove derived organic matter in the sediment cores

    Digital Repository Service at National Institute of Oceanography (India)

    Manju, M.N.; Resmi, P.; RatheeshKumar, C.S.; Gireeshkumar, T.R.; Chandramohanakumar, N.; Joseph, M.M.

    in mangrove sediments. This also confirms the involvement of heterotrophic microorganisms in the organic carbon dynamics of the study area. The bulk elemental ratio (total organic carbon/total nitrogen) varied between 11.39 and 24.14 in the study region...

  5. Preliminary attempt to distinguish the domesticated pigs from wild boars by the methods of carbon and nitrogen stable isotope analysis

    Institute of Scientific and Technical Information of China (English)

    HU YaoWu; LUAN FengShi; WANG ShouGong; WANG ChangSui; Michael P. RICHARDS

    2009-01-01

    Despite great achievements in the origins of domestic pigs made by the methods of zooarchaeology and molecular biology, how to scientifically distinguish the domesticated pigs from wild boars during the early stage of pig domestication is still poorly understood. Compared to wild boar's diets which come from the natural environment, the diets of domestic pigs are more easily influenced by human feeding activities. Therefore, in principle, exploration of the dietary differences among pigs and under standing the impact on pig diets fed by humans can have great potential to differentiate between wild boars and domesticated pigs. To reveal dietary differences among pigs and distinguish the domesti cated pigs from wild boars based on comparison with the diets of humans and other animals, we ana lyzed the carbon and nitrogen stable isotopes of human bones from Xiaojingshan Site and animal bones from Yuezhuang Site, both of which belong to Houli Culture in Shandong Province and date to about 8500--7500 years ago. The mean б13C value ((-17.8 ± 0.3)%o) and б15N value ((9.0±0.6)%0) in human collagen indicate that although millet agriculture began it was not the main subsistence strategy as millets are typical of C4 plants and that humans made a living mainly by gathering, hunting or raisingsome domesticated animals. The б13C value (-16.1%.) and б15N value (6.9%.) in the bovine suggest that C3 plants were dominant in its diet with some C4 plants complemented. The fish has lower б13C value (-24.9%.) and higher б15N value (8.8%.) than the bovine, which is the characteristic of the isotopic val ues from Eurasian freshwater fish. Based on the differences in carbon and nitrogen isotope values, the pigs can be divided into three groups. A group, composed of two pigs, has low б13C values (-18.1%o,-20.0%o) and low б15N values (4.7%o, 6.0%.). B group, only one pig, has the highest б13C value (-10.6%o)and mediate б15N value (6.4%.). As for the C group, also only one pig

  6. Preliminary attempt to distinguish the domesticated pigs from wild boars by the methods of carbon and nitrogen stable isotope analysis

    Institute of Scientific and Technical Information of China (English)

    Michael; P.RICHARDS

    2009-01-01

    Despite great achievements in the origins of domestic pigs made by the methods of zooarchaeology and molecular biology,how to scientifically distinguish the domesticated pigs from wild boars during the early stage of pig domestication is still poorly understood.Compared to wild boar’s diets which come from the natural environment,the diets of domestic pigs are more easily influenced by human feeding activities.Therefore,in principle,exploration of the dietary differences among pigs and understanding the impact on pig diets fed by humans can have great potential to differentiate between wild boars and domesticated pigs.To reveal dietary differences among pigs and distinguish the domesticated pigs from wild boars based on comparison with the diets of humans and other animals,we analyzed the carbon and nitrogen stable isotopes of human bones from Xiaojingshan Site and animal bones from Yuezhuang Site,both of which belong to Houli Culture in Shandong Province and date to about 8500―7500 years ago.The mean δ 13C value((-17.8 ± 0.3)‰) and δ 15N value((9.0±0.6)‰) in human collagen indicate that although millet agriculture began it was not the main subsistence strategy as millets are typical of C4 plants and that humans made a living mainly by gathering,hunting or raising some domesticated animals.The δ 13C value(-16.1‰) and δ 15N value(6.9‰) in the bovine suggest that C3 plants were dominant in its diet with some C4 plants complemented.The fish has lower δ 13C value(-24.9‰) and higher δ 15N value(8.8‰) than the bovine,which is the characteristic of the isotopic values from Eurasian freshwater fish.Based on the differences in carbon and nitrogen isotope values,the pigs can be divided into three groups.A group,composed of two pigs,has low δ 13C values(-18.1‰,-20.0‰) and low δ 15N values(4.7‰,6.0‰).B group,only one pig,has the highest δ 13C value(-10.6‰) and mediate δ 15N value(6.4‰).As for the C group,also only one pig,low δ 13C

  7. Establishment of trophic continuum in the food web of the Yellow Sea and East China Sea ecosystem: Insight from carbon and nitrogen stable isotopes

    Institute of Scientific and Technical Information of China (English)

    CAI Deling; LI Hongyan; TANG Qisheng; SUN Yao

    2005-01-01

    Stable carbon and nitrogen isotope ratios (δ13C and δ15N) are used to study the trophic structure of food web in the Yellow Sea and East China Sea ecosystem. The trophic continuum of pelagic food web from phytoplankton to top preyer was elementarily established, and a trophic structure diagram in the Yellow Sea and East China Sea was outlined in combination with carbon isotopic data of benthic organisms, which is basically consistent with and makes some improvements on the simplified Yellow Sea food web and the trophic structure diagram drawn based on the biomass of main resource population during 1985―1986. This result indicates that the stable isotope method is a potential useful means for further studying the complete marine food web trophic continuum from viruses to top predators and food web stability.

  8. Establishment of trophic continuum in the food web of the Yellow Sea and East China Sea ecosystem: insight from carbon and nitrogen stable isotopes.

    Science.gov (United States)

    Cai, Deling; Li, Hongyan; Tang, Qisheng; Sun, Yao

    2005-12-01

    Stable carbon and nitrogen isotope ratios (delta (13)C and delta (15)N) are used to study the trophic structure of food web in the Yellow Sea and East China Sea ecosystem. The trophic continuum of pelagic food web from phytoplankton to top preyer was elementarily established, and a trophic structure diagram in the Yellow Sea and East China Sea was outlined in combination with carbon isotopic data of benthic organisms, which is basically consistent with and makes some improvements on the simplified Yellow Sea food web and the trophic structure diagram drawn based on the biomass of main resource population during 1985-1986. This result indicates that the stable isotope method is a potential useful means for further studying the complete marine food web trophic continuum from viruses to top predators and food web stability. PMID:16483132

  9. Chemostratigraphy of stable chromium isotopes in cap carbonate sequences - tracing the aftermath of Earth's Neoproterozoic icehouse climates

    Science.gov (United States)

    Frei, R.; de Andrade Caxito, F.; Gaucher, C.

    2012-12-01

    fluctuations can be interpreted to reflect increased continentally-derived input into the shallow seawater (increasing δ18O and increasingly positively fractionated (δ53Cr values thought to mirror increased mobilization of hexavalent [Cr(VI)] from the landmasses. Photosynthetic algae blooms in the aftermath of the icehouse climate would likely explain the increasing δ13C values of the studied carbonates deposited atop the cap dolostones. Chromium stable isotopes prove to be a suitable tracer for hydrothermal vs. continental influx into shallow seawater and have the potential to connect to the degree of oxidative weathering conditions on land. Schoenberg et al. (2008) Chemical Geology, 249, 294-306 Caxito et al. (2012) Precambrian Research, 200-203, 38

  10. Carbonation rates of peridotite in the Samail Ophiolite, Sultanate of Oman, constrained through 14C dating and stable isotopes

    Science.gov (United States)

    Mervine, Evelyn M.; Humphris, Susan E.; Sims, Kenneth W. W.; Kelemen, Peter B.; Jenkins, William J.

    2014-02-01

    Detailed 14C dating as well as stable C and O isotope analyses were conducted on carbonates formed during alteration of the peridotite layer of the Samail Ophiolite, Sultanate of Oman. 14C results obtained in this and previous studies indicate that surface travertines range in age from modern to >45,000 yr BP, indicating long-term deposition and preservation. Travertine deposition rates in two localities were ˜0.1 to 0.3 mm/yr between ˜30,000 and 45,000 yr BP. Using an estimate of total travertine area, this would result in a maximum of ˜1000 to 3000 m3/yr of travertine being deposited throughout the ophiolite during this time period. This travertine deposition would have sequestered a maximum of ˜1 to 3 × 106 kg CO2/yr. Ca-rich carbonate veins that are associated with the surface travertine deposits have ages ranging from ˜4000 to 36,000 yr BP (average: 15,000 yr BP). Mg-rich carbonate veins exposed in outcrops have ages ranging from ˜8000 to 45,000 yr BP (average: 35,000 yr BP). Detailed sampling from numerous locations (3 locations in this study and 10 locations in the previous studies) indicates that no carbonate veins from the natural peridotite weathering surface are older than the ˜50,000 yr BP dating limit of 14C. However, 14C dating of Mg-rich carbonate veins from three roadcut exposures (Qafeefah, Fanja, and Al-Wuqbah) indicates that a significant number of roadcut veins are 14C dead (>50,000 yr BP). A location weighted average indicates that ˜40% of veins sampled at the three roadcuts are 14C dead. An average including veins sampled at both roadcuts and outcrops indicates that overall ˜8% of Mg-rich carbonate veins are 14C dead. Mg-rich carbonate veins are estimated to sequester on the order of 107 kg CO2/yr throughout the ophiolite.

  11. Bayesian stable isotope mixing models

    Science.gov (United States)

    In this paper we review recent advances in Stable Isotope Mixing Models (SIMMs) and place them into an over-arching Bayesian statistical framework which allows for several useful extensions. SIMMs are used to quantify the proportional contributions of various sources to a mixtur...

  12. Paleoproxies: Heavy Stable Isotope Perspectives

    Science.gov (United States)

    Nagler, T. F.; Hippler, D.; Siebert, C.; Kramers, J. D.

    2002-12-01

    Recent advances in isotope ratio mass spectrometry, namely multiple collector ICP-MS and refined TIMS techniques, will significantly enhance the ability to measure heavy stable isotope fractionation, which will lead to the development of a wide array of process-identifying (bio)-geochemical tools. Thus far research in this area is not easily assessable to scientists outside the isotope field. This is due to the fact that analyzing heavy stable isotopes does not provide routine numbers which are per se true (the preciser the truer) but is still a highly experimental field. On the other hand resolving earth science problems requires specialists familiar with the environment being studied. So what is in there for paleoceanographers? In a first order approach, relating isotope variations to physical processes is straightforward. A prominent example are oxygen isotope variations with temperature. The total geological signal is of course far more complicated. At low temperatures, heavy stable isotopes variations have been reported for e.g. Ca, Cr, Fe, Cu, Zn, Mo and Tl. Fractionation mechanisms and physical parameters responsible for the observed variations are not yet resolved for most elements. Significant equilibrium isotope fractionation is expected from redox reactions of transition metals. However a difference in coordination number between two coexisting speciations of an element in the same oxidation state can also cause fractionation. Protonation of dissolved Mo is one case currently discussed. For paleoceanography studies, a principal distinction between transition metals essential for life (V to Zn plus Mo) or not will be helpful. In case of the former group, distinction between biogenic and abiogenic isotope fractionation will remain an important issue. For example, abiotic Fe redox reactions result in isotope fractionations indistinguishable in direction and magnitude from microbial effects. Only a combination of different stable isotope systems bears the

  13. Assessment of Soil Organic Carbon Stability in Agricultural Systems by Using Natural Abundance Signals of Stable Carbon and Nitrogen Isotopes

    International Nuclear Information System (INIS)

    Information on the stability and age of soil organic matter (SOM) pools is of vital importance for assessing the impact of soil management and environmental factors on SOM, an important part of the global carbon (C) cycle. The terrestrial soil organic C pool, up to a depth of 1 m, contains about 1500 Pg C (Batjes, 1996). This is about 2.5 times more organic C than the vegetation (650 Pg C) and about twice as much as in the atmosphere (750 Pg C) (Batjes, 1998), but the assessment of the stability and age of SOM using 14C radio carbon technique are expensive. Conen et al. (2008) developed a model to estimate the SOM stability based on the isotopic discrimination of 15N natural abundance by soil micro-organisms and the change in C/N ratio during organic matter decomposition, for steady state, Alpine and permanent grasslands. In the framework of the IAEA funded coordinated research project (CRP) on Soil Quality and Nutrient Management for Sustainable Food Production in Mulch based Cropping Systems in sub-Saharan Africa, research was initiated to use this model in agricultural systems for developing a cost effective and affordable technique for Member States to determine the stability of SOM. As part of this research, soil samples were taken and analysed in four long term field experiments, established on soils with low and high SOM, in Austria and Belgium. The participating institutions are the Austrian Agency for Health and Food Safety (AGES), the University of Natural Resources and Life Sciences in Vienna (BOKU), the University of Leuven (KUL), the Soil Service of Belgium (BDB) and the Centre Wallon de Recherches Agronomiques (CRA-W)

  14. Differential utilization of allochthonous and autochthonous carbon by aquatic insects of two shrub-steppe desert spring-streams: A stable carbon isotope analysis and critique of the method

    Energy Technology Data Exchange (ETDEWEB)

    Mize, A.L. [Old Dominion Univ., Norfolk, VA (United States)

    1993-06-01

    The purpose of this study is to assess whether the carbon supporting stream food webs comes principally from terrestrial sources or is produced within the stream. Lacking data to resolve the allochthonous/autochthonous issue with any finality, stream ecologists have alternately postulated that stream carbon was principally autochthonous or principally allochthonous. Others argued that autochthonous and allochthonous carbon resources cannot be separated and that the allochthonous/autochthonous dependence issue is unresolvable. Many investigators have seized upon stable carbon isotopes technology as the tool to resolve the controversy. Unfortunately most investigators have conceded that the results are rarely quantitative and that the qualitative relationships are ambiguous. This study points out the fallacies of trying to conjure single isotopic values for either allochthonous or autochthonous carbon. It suggests that stable carbon isotope technology is not reliable in establishing specific consumer/food source relations and that it is not suitable for assessing allochthonous/autochthonous carbon dependence in freshwater streams.

  15. 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...

  16. Methane-producing bacteria - Natural fractionations of the stable carbon isotopes

    Science.gov (United States)

    Games, L. M.; Hayes, J. M.; Gunsalus, R. P.

    1978-01-01

    Procedures for determining the C-13/C-12 fractionation factors for methane-producing bacteria are described, and the fractionation factors (CO2/CH4) for the reduction of CO2 to CH4 by pure cultures are 1.045 for Methanosarcina barkeri at 40 C, 1.061 for Methanobacterium strain M.o.H. at 40 C, and 1.025 for Methanobacterium thermoautotrophicum at 65 C. The data are consistent with the field determinations if fractionation by acetate dissimilation approximates fractionations observed in natural environments. In other words, the acetic acid used by acetate dissimilating bacteria, if they play an important role in natural methane production, must have an intramolecular isotopic fractionation (CO2H/CH3) approximating the observed CO2/CH4 fractionation.

  17. Carbon stable isotopic composition of karst soil CO2 in central Guizhou, China

    Institute of Scientific and Technical Information of China (English)

    郑乐平

    1999-01-01

    The δ13 values of soil CO2 are less than that of atmosphere CO2 in the karst area. On the soil-air interface, the δ13 vlaues of soil CO2 decrease with the increase in soil depth; below the soil-air interface, the δ13C values of soil CO2 are invariable. The type of vegetation on the land surface has an influence on the δ13C values of soil CO2 Due to the activity of soil microbes, the δ13C values of soil CO2 are variable with seasonal change in grass. Isotopic tracer indicates that atmosphere CO2 has a great deal of contribution to soil CO2 at the lower parts of soil profile.

  18. Stable carbon and nitrogen isotopic composition of bulk aerosols over India and northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Agnihotri, R.; Mandal, T.K.; Karapurkar, S.; Naja, M.; Gadi, R.; Ahammed, Y.N.; Kumar, A.; Saud, T.; Saxena, M.

    occurring in fine mode fraction of aerosols. As continental polluted air is diluted, NH 4 NO 3 can be disassociated and reformed HNO 3 can react with aerosol carbonate or sea salt in marine realm (Widory et al., 2007). Thus N incorporation in aerosols...

  19. Isotopes Will Let the Cat Out of the Bag: A Carbon and Nitrogen Stable Isotopic Analysis of Dry Cat Food Brands

    Science.gov (United States)

    Zelanko, P. M.

    2011-12-01

    There are a plethora of healthy cat food brands that make a wide variety of claims about the nutrition of their product and the lack of nutrition of their competitors. The claims range from "No sugar or corn" to "Real meat is always the 1st ingredient". The two major disagreements in the cat food market are the nutritional value of corn and the realness of meat products. Here I present a carbon and nitrogen stable isotopic analysis of a wide range of dry cat food brands. The beginning assumption was brands with claims of no corn would be depleted in δ13C compared to brands with corn and brands with real meat as the 1st ingredient would be enriched in δ 15N compared to brands with meat as a lesser ingredient. Preliminary results show brands with no corn (δ13C ~ -22%) are depleted compared to brands with corn (δ13C ~ -17%), which is to be expected. However, brands that claim real meat is the 1st ingredient are slightly depleted (δ15N ~ 3.5%) compared to brands with proportionally less meat (δ15N ~ 5%); the opposite of what was anticipated. Also, the stable isotopes of three house cats, that were all fed the same dry diet (corn as major ingredient), were tracked over time as they were switched to a diet with no corn. Variation was present in the first round of analysis and persisted throughout the dietary change, suggesting individual cats may absorb nutrients from the identical diets differently.

  20. Latitudinal gradients in tree ring stable carbon and oxygen isotopes reveal differential climate influences of the North American Monsoon System

    Science.gov (United States)

    Szejner, Paul; Wright, William E.; Babst, Flurin; Belmecheri, Soumaya; Trouet, Valerie; Leavitt, Steven W.; Ehleringer, James R.; Monson, Russell K.

    2016-07-01

    The arrival of the North American Monsoon System (NAMS) terminates a presummer hyperarid period in the southwestern United States (U.S.), providing summer moisture that is favorable for forest growth. Montane forests in this region rely on winter snowpack to drive much of their growth; the extent to which they use NAMS moisture is uncertain. We addressed this by studying stable carbon and oxygen isotopes in earlywood and latewood from 11 sites along a latitudinal gradient extending from Arizona and New Mexico to Utah. This study provides the first regional perspective on the relative roles of winter versus summer precipitation as an ecophysiological resource. Here we present evidence that Ponderosa pine uses NAMS moisture differentially across this gradient. 13C/12C ratios suggest that photosynthetic water use efficiency during latewood formation is more sensitive to summer precipitation at the northern than at the southern sites. This is likely due to the fact that NAMS moisture provides sufficiently favorable conditions for tree photosynthesis and growth during most years in the southern sites, whereas the northern sites experience larger summer moisture variability, which in some years is limiting growth. Cellulose δ18O and δ13C values revealed that photoassimilates in the southern sites were produced under higher vapor pressure deficit conditions during spring compared to summer, demonstrating a previously underappreciated effect of seasonal differences in atmospheric humidity on tree ring isotope ratios. Our findings suggest that future changes in NAMS will potentially alter productivity and photosynthetic water use dynamics differentially along latitudinal gradients in southwestern U.S. montane forests.

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

    Energy Technology Data Exchange (ETDEWEB)

    Irei, Satoshi, E-mail: irei.satoshi@nies.go.jp [Centre for Atmospheric Chemistry, Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3 (Canada); Climate Research Division, Atmospheric Science and Technology Directorate, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4 (Canada); Rudolph, Jochen [Centre for Atmospheric Chemistry, Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3 (Canada); Huang, Lin [Climate Research Division, Atmospheric Science and Technology Directorate, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4 (Canada)

    2013-07-05

    Graphical abstract: -- Highlights: •For GCC–IRMS analysis, an approach avoiding impact of NO{sub 2} on δ{sup 13}C 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 (δ{sup 13}C) 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 δ{sup 13}C values: (1) for nitro compounds, the routine correction with use of m/z 46 for the contribution of {sup 12}C{sup 17}O{sup 16}O molecules) to m/z 45 was modified due to impact of NO{sub 2} on the m/z 46 trace, and (2) for the derivatized phenols, measured δ{sup 13}C values were corrected for the shift in δ{sup 13}C 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 δ{sup 13}C 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

  2. Testing of an automated online EA-IRMS method for fast and simultaneous carbon content and stable isotope measurement of aerosol samples

    Science.gov (United States)

    Major, István; Gyökös, Brigitta; Túri, Marianna; Futó, István; Filep, Ágnes; Hoffer, András; Molnár, Mihály

    2016-04-01

    Comprehensive atmospheric studies have demonstrated that carbonaceous aerosol is one of the main components of atmospheric particulate matter over Europe. Various methods, considering optical or thermal properties, have been developed for quantification of the accurate amount of both organic and elemental carbon constituents of atmospheric aerosol. The aim of our work was to develop an alternative fast and easy method for determination of the total carbon content of individual aerosol samples collected on prebaked quartz filters whereby the mass and surface concentration becomes simply computable. We applied the conventional "elemental analyzer (EA) coupled online with an isotope ratio mass spectrometer (IRMS)" technique which is ubiquitously used in mass spectrometry. Using this technique we are able to measure simultaneously the carbon stable isotope ratio of the samples, as well. During the developing process, we compared the EA-IRMS technique with an off-line catalytic combustion method worked out previously at Hertelendi Laboratory of Environmental Studies (HEKAL). We tested the combined online total carbon content and stable isotope ratio measurement both on standard materials and real aerosol samples. Regarding the test results the novel method assures, on the one hand, at least 95% of carbon recovery yield in a broad total carbon mass range (between 100 and 3000 ug) and, on the other hand, a good reproducibility of stable isotope measurements with an uncertainty of ± 0.2 per mill. Comparing the total carbon results obtained by the EA-IRMS and the off-line catalytic combustion method we found a very good correlation (R2=0.94) that proves the applicability of both preparation method. Advantages of the novel method are the fast and simplified sample preparation steps and the fully automated, simultaneous carbon stable isotope ratio measurement processes. Furthermore stable isotope ratio results can effectively be applied in the source apportionment

  3. Response of stable carbon isotope in epilithic mosses to atmospheric nitrogen deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xueyan, E-mail: liuxueyan@vip.skleg.c [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 (China); Xiao Huayun; Liu Congqiang [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 (China); Li Youyi; Xiao Hongwei; Wang Yanli [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 (China); Graduate University of Chinese Academy of Sciences, Yuquanlu, Beijing 100049 (China)

    2010-06-15

    Epilithic mosses are characterized by insulation from substratum N and hence meet their N demand only by deposited N. This study investigated tissue C, total Chl and delta{sup 13}C of epilithic mosses along 2 transects across Guiyang urban (SW China), aiming at testing their responses to N deposition. Tissue C and total Chl decreased from the urban to rural, but delta{sup 13}C{sub moss} became less negative. With measurements of atmospheric CO{sub 2} and delta{sup 13}CO{sub 2}, elevated N deposition was inferred as a primary factor for changes in moss C and isotopic signatures. Correlations between total Chl, tissue C and N signals indicated a nutritional effect on C fixation of epilithic mosses, but the response of delta{sup 13}C{sub moss} to N deposition could not be clearly differentiated from effects of other factors. Collective evidences suggest that C signals of epilithic mosses are useful proxies for N deposition but further works on physiological mechanisms are still needed. - Photosynthetic {sup 13}C discrimination of bryophytes might increase with elevated N deposition.

  4. Stable carbon isotopes to monitor the CO2 source mix in the urban environment

    Science.gov (United States)

    Vogel, F. R.; Wu, L.; Ramonet, M.; Broquet, G.; Worthy, D. E. J.

    2014-12-01

    Urban areas are said to be responsible for approximately 71% of fossil fuel CO2 emissions while comprising only two percent of the land area [IEA, 2008]. This limited spatial expansion could facility a monitoring of anthropogenic GHGs from atmospheric observations. As major sources of emissions, cities also have a huge potential to drive emissions reductions. To effectively manage emissions, cities must however, first establish techniques to validate their reported emission statistics. A pilot study which includes continues 13CO2 data from calibrated cavity ring-down spectrometers [Vogel et al. 2013] of two "sister sites" in the vicinity of Toronto, Canada is contrasted to recent observations of 13CO2 observations in Paris during significant pollution events. Using Miller-Tans plots [Miller and Tans, 2003] for our multi-season observations reveals significant changes of the source signatures of night time CO2 emissions which reflect the importance of natural gas burning in Megacities (up to 80% of fossil fuel sources) and show-case the potential of future isotope studies to determine source sectors. Especially the winter data this approach seems suitable to determine the source contribution of different fuel types (natural gas, liquid fuels and coal) which can inform the interpretation of other Greenhouse Gases and air pollution levels.

  5. Stable carbon isotope evidence for tracing the diet of the host Hepialus larva of Cordyceps sinensis in the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Two types of Hepialus larvae with different diets were distinguished in the Sejila Mountain,Tibetan Plateau based on the stable carbon isotope data of the host Hepialus larva of Cordyceps sinensis and its closely adjacent tender plant roots and humus fractions.Type I is the larva chiefly fed by soil humus,and characterized by the δ 13C values of -22.6‰ to-23.4‰,and more than -23.4‰ in its heads.Type II is the larva chiefly fed by tender plant roots,and characterized by the δ 13C values of-24.6‰ to -27.6‰,and less than -24.6‰ in its heads.Our result has exceeded the traditional understanding that their food sources only come from the tender plant roots,and may provide evidence for choosing cheap and high-quality foods and further establishing artificial habitats in their large-scale reproduction.

  6. Ordovician meteoric carbon and oxygen isotopic values: Implications for the latitudinal variations of ancient stable isotopic values

    Science.gov (United States)

    Tobin, K.J.; Steinhauff, D.M.; Walker, K.R.

    1999-01-01

    Columnar and clear blocky calcite cement from a Middle Ordovician carbonate succession in east Tennessee is interpreted as meteoric in origin. Columnar and clear blocky calcite from this succession does not show extremely large 13C depletions reported from meteoric phases of younger rocks. Meteoric fluid ??18O values calculated from clear blocky calcite are ??? 2 to 3??? more negative than approximately coeval sea water; a relationship typical of modern, low-latitude, coastal meteoric water. Comparison with meteoric ??18O values from Ordovician units elsewhere suggests that the geographic distribution of these values may be broadly similar to that observed today. Therefore, we tentatively suggest that geographic distribution of meteoric ??18O values during both icehouse and greenhouse eras are similar.

  7. Assessing the Utility of Hydrogen, Carbon and Nitrogen Stable Isotopes in Estimating Consumer Allochthony in Two Shallow Eutrophic Lakes

    DEFF Research Database (Denmark)

    Syväranta, Jari; Scharnweber, Kristin; Brauns, Mario;

    2016-01-01

    Hydrogen stable isotopes (δ2H) have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potenti...

  8. Stable isotope ratios of carbon and hydrogen to distinguish olive oil from shark squalene-squalane.

    Science.gov (United States)

    Camin, Federica; Bontempo, Luana; Ziller, Luca; Piangiolino, Cristiana; Morchio, Gianni

    2010-06-30

    Squalene and its hydrogenated derivate squalane are widely used in the pharmaceutical and cosmetic fields. The two compounds are mainly produced from the liver oil of deep sea sharks and from olive oil distillates. Squalene and squalane from shark cost less than the same compounds derived from olive oil, and the use of these shark-derived compounds is unethical in cosmetic formulations. In this work we investigate whether (13)C/(12)C and (2)H/(1)H ratios can distinguish olive oil from shark squalene/squalane and can detect the presence of shark derivates in olive oil based products. The (13)C/(12)C ratios (expressed as delta(13)C values) of bulk samples and of pure compounds measured using isotope ratio mass spectrometry (IRMS) were significantly lower in authentic olive oil squalene/squalane (N: 13; -28.4 +/- 0.5 per thousand; -28.3 +/- 0.8 per thousand) than in shark squalene/squalane samples (N: 15; -20.5 +/- 0.7 per thousand; -20.4 +/- 0.6 per thousand). By defining delta(13)C threshold values of -27.4 per thousand and -26.6 per thousand for olive oil bulk and pure squalene/squalane, respectively, illegal addition of shark products can be identified starting from a minimum of 10%. (2)H/(1)H analysis is not useful for distinguishing the two different origins. Delta(13)C analysis is proposed as a suitable tool for detecting the authenticity of commercial olive oil squalene and squalane samples, using IRMS interfaced to an elemental analyser if the purity is higher than 80% and IRMS interfaced to a gas chromatography/combustion system for samples with lower purity, including solutions of squalane extracted from cosmetic products.

  9. 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

  10. Fractional Absorption of Active Absorbable Algal Calcium (AAACa and Calcium Carbonate Measured by a Dual Stable-Isotope Method

    Directory of Open Access Journals (Sweden)

    Steven A. Abrams

    2010-07-01

    Full Text Available With the use of stable isotopes, this study aimed to compare the bioavailability of active absorbable algal calcium (AAACa, obtained from oyster shell powder heated to a high temperature, with an additional heated seaweed component (Heated Algal Ingredient, HAI, with that of calcium carbonate. In 10 postmenopausal women volunteers aged 59 to 77 years (mean ± S.D., 67 ± 5.3, the fractional calcium absorption of AAACa and CaCO3 was measured by a dual stable isotope method. 44Ca-enriched CaCO3 and AAACa were administered in all subjects one month apart. After a fixed-menu breakfast and pre-test urine collection (Urine 0, 42Ca-enriched CaCl2 was intravenously injected, followed by oral administration of 44Ca-enriched CaCO3 without carrier 15 minutes later, and complete urine collection for the next 24 hours (Urine 24. The fractional calcium absorption was calculated as the ratio of Augmentation of 44Ca from Urine 0 to Urine 24/ augmentation of 42Ca from Urine 0 to Urine 24. Differences and changes of 44Ca and 42Ca were corrected by comparing each with 43Ca. Fractional absorption of AAACa (mean ± S.D., 23.1 ± 6.4, was distinctly and significantly higher than that of CaCO3 (14.7 ± 6.4; p = 0.0060 by paired t-test. The mean fractional absorption was approximately 1.57-times higher for AAACa than for CaCO3. The serum 25(OH vitamin D level was low (mean ± S.D., 14.2 ± 4.95 ng/ml, as is common in this age group in Japan. Among the parameters of the bone and mineral metabolism measured, none displayed a significant correlation with the fractional absorption of CaCO3 and AAACa. Higher fractional absorption of AAACa compared with CaCO3 supports previous reports on the more beneficial effect of AAACa than CaCO3 for osteoporosis.

  11. 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

  12. Molecular distributions and compound-specific stable carbon isotopic compositions of lipids in wintertime aerosols from Beijing

    Science.gov (United States)

    Ren, Lujie; Fu, Pingqing; He, Yue; Hou, Juzhi; Chen, Jing; Pavuluri, Chandra Mouli; Sun, Yele; Wang, Zifa

    2016-06-01

    Molecular distributions and stable carbon isotopic compositions (δ13C) of n-alkanes, fatty acids and n-alcohols were investigated in urban aerosols from Beijing, northern China to better understand the sources and long-range atmospheric transport of terrestrial organic matter during polluted and clear days in winter. n-Alkanes (C19–C36), fatty acids (C8–C32) and n-alcohols (C16–C32) detected in Beijing aerosols are characterized by the predominance of C23, C16 and C28, respectively. Carbon preference index (CPI) values of n-alkanes, the ratios of the sum of odd-numbered n-alkanes to the sum of even-numbered n-alkanes, are close to 1, indicating a heavy influence of fossil fuel combustion. Relatively higher ratios of C(18:0+16:0)/C(18:n+16:1) (fatty acids) on clear days than polluted days indicate that long-distance transport and/or photochemical aging are more significant during clear days. δ13C values of n-alkanes and low molecular weight fatty acids (C16:0, C18:0) ranged from –34.1 to ‑24.7% and ‑26.9 to ‑24.6%, respectively, which are generally heavier on polluted days than those on clear days. Such a wide range suggests that atmospheric lipids in Beijing aerosols originate from multiple sources and encounter complicated atmospheric processes during long-range transport in North China.

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

    Science.gov (United States)

    Irei, Satoshi; Rudolph, Jochen; Huang, Lin

    2013-07-01

    We developed an analytical method for measuring compound-specific stable carbon isotope ratios (δ(13)C) 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 δ(13)C values: (1) for nitro compounds, the routine correction with use of m/z 46 for the contribution of (12)C(17)O(16)O 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 δ(13)C values were corrected for the shift in δ(13)C 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 δ(13)C 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 δ(13)C values. We also analyzed a real filter sample to demonstrate the practical applicability of the method.

  14. Methanotrophy in London, UK, Landfill Topsoil: Microbiology, Stable Carbon Isotopes, Seasonal Variation and Laboratory Model Study

    Science.gov (United States)

    Sriskantharajah, S.; Fisher, R.; Lowry, D.; Grassineau, N.; Nisbet, E. G.

    2004-12-01

    Landfill is a major source of methane emissions into the atmosphere. Aerobic soil is also a good sink of methane, as it is inhabited by methane consuming bacteria, methanotrophs. Methanotrophic bacteria were cultured from landfill soil samples. Three genera of methanotrophs were cultured: Methylocaldum, Methylosinus and Methylomonas. Interestingly, the only established members of the Methylocaldum genus are all thermophilic, whilst those isolated in this study are mesophilic. This suggests that those Methylocaldum methanotrophs found in landfills may have migrated from hot spring natural settings. Representatives of each genera were inoculated into a simple topsoil model and subjected to variations in temperature, methane concentration and incubation periods. As expected, temperature greatly affected methane oxidation, but methane concentration affected the rate of oxidation far more than expected. The model study implies that the complete combustion of methane to carbon dioxide is greatly affected by temperature and methane availability, whilst the effect on the uptake of methane is not as great. Seasonal variations in methane concentrations within the topsoil were monitored over a one year period from November 2002 to October 2003 and show that methane flow through the topsoil, and consequently methanotrophy, is strongly controlled by meteorology, mainly air temperature and pressure. Generally, methanotrophy was low during colder months and higher at during warmer months, but changes in air pressure complicate this by controlling the rate of flow of methane through the topsoil. δ 13C analyses of methane and carbon dioxide emitted from landfill topsoil showed that there was a great deal of methanotrophic activity during the warmer months of 2003, with most fractionation of residual methane occurring during August. During the heat wave experienced in the UK in August 2003, the δ 13C from borehole samples of methane in the anaerobic zone shifted from -57‰ to -16

  15. Bayesian Stable Isotope Mixing Models

    OpenAIRE

    Parnell, Andrew C.; Phillips, Donald L.; Bearhop, Stuart; Semmens, Brice X.; Ward, Eric J.; Moore, Jonathan W.; Andrew L Jackson; Inger, Richard

    2012-01-01

    In this paper we review recent advances in Stable Isotope Mixing Models (SIMMs) and place them into an over-arching Bayesian statistical framework which allows for several useful extensions. SIMMs are used to quantify the proportional contributions of various sources to a mixture. The most widely used application is quantifying the diet of organisms based on the food sources they have been observed to consume. At the centre of the multivariate statistical model we propose is a compositional m...

  16. Stable carbon isotopic compositions of intact polar lipids reveal complex carbon flow patterns among hydrocarbon degrading microbial communities at the Chapopote asphalt volcano

    Science.gov (United States)

    Schubotz, Florence; Lipp, Julius S.; Elvert, Marcus; Hinrichs, Kai-Uwe

    2011-08-01

    Seepage of asphalt forms the basis of a cold seep system at 3000 m water depth at the Chapopote Knoll in the southern Gulf of Mexico. Anaerobic microbial communities are stimulated in the oil-impregnated sediments as evidenced by the presence of intact polar membrane lipids (IPLs) derived from archaea and Bacteria at depths up to 7 m below the seafloor. Detailed investigation of stable carbon isotope composition (δ 13C) of alkyl and acyl moieties derived from a range of IPL precursors with distinct polar head groups resolved the complexity of carbon metabolisms and utilization of diverse carbon sources by uncultured microbial communities. In surface sediments most of the polar lipid-derived fatty acids with phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG) head groups could be tentatively assigned to autotrophic sulfate-reducing bacteria, with a relatively small proportion involved in the anaerobic oxidation of methane. Derivatives of phosphatidyl-( N)-methylethanolamine (PME) were abundant and could be predominantly assigned to heterotrophic oil-degrading bacteria. Archaeal IPLs with phosphate-based hydroxyarchaeols and diglycosidic glyceroldibiphytanylglyceroltetraethers (GDGTs) were assigned to methanotrophic archaea of the ANME-2 and ANME-1 cluster, respectively, whereas δ 13C values of phosphate-based archaeols and mixed phosphate-based and diglycosidic GDGTs point to methanogenic archaea. At a 7 m deep sulfate-methane transition zone that is linked to the upward movement of gas-laden petroleum, a distinct increase in abundance of archaeal IPLs such as phosphate-based hydroxyarchaeols and diglycosidic archaeol and GDGTs is observed; their δ 13C values are consistent with their origin from both methanotrophic and methanogenic archaea. This study reveals previously hidden, highly complex patterns in the carbon-flow of versatile microbial communities involved in the degradation of heavy oil including hydrocarbon gases

  17. Stable sulfur and carbon isotope investigations of pore-water and solid-phase compounds in sediments of the Chapopote Asphalt Volcano, southern Gulf of Mexico

    Science.gov (United States)

    Wilhelm, T.; Bruechert, V.; Pape, T.; Schubotz, F.; Kasten, S.

    2007-05-01

    During R/V Meteor cruise M67 2a/b (March-April 2006) to the Asphalt Volcanoes of the southern Gulf of Mexico two gravity cores were retrieved from the central depression of the Chapopote Knoll which contained viscous oil/asphalt a few meters below the sediment surface. Also several push cores were taken with the remotely operated vehicle (ROV) QUEST at sites where oil/asphalt reached closely below the sediment surface. From these cores solid-phase and pore-water samples were taken for on-board and subsequent shore-based analyses. Together with a core taken from a background site which is not influenced by asphalt/oil seepage these sediment and pore water samples are currently subject to detailed analyses of (1) the stable sulfur isotopic composition of both dissolved (sulfate and sulfide) and solid-phase (iron monosulfides, pyrite) sulfur compounds, and (2) the composition and stable carbon isotopic signatures of hydrocarbon gases. The major aims of these investigations are to identify whether and to which extent the upward migration of oil, asphalt and gas (1) stimulates biogeochemical processes and turn-over rates, and (2) influences the stable sulfur isotopic signatures of both dissolved and solid phase sulfur compounds. Furthermore, we seek to determine the potential of these - possibly unusual - stable sulfur isotopic signals of solid-phase sulfides to reconstruct hydrocarbon seepage in older geological records and to elucidate how the composition and the stable carbon isotopic signatures of the hydrocarbon gases are altered by the action of typical chemosynthetic communities thriving at these sites.

  18. Interannual variability in seagrass carbon and nitrogen stable isotopes from the Florida Keys National Marine Sanctuary, a preliminary study

    Science.gov (United States)

    Fourqurean, J. W.; Fourqurean, J. W.; Anderson, W. T.; Anderson, W. T.

    2001-12-01

    The shallow marine waters surrounding the southern tip of Florida provide an ideal environment for seagrasses, which are the most common benthic community in the region. Yet, these communities are susceptible to a variety of anthropogenic disturbances, especially changes in water quality caused by an increase the nutrient flux to the near shore environment. In order to better understand the carbon and nitrogen isotopic ratio in marine plants, an extensive times series analysis was constructed from quarterly sampling of Thalassia testudinum (the dominate species in the study area) from 1996 through 1998. Sites for study where selected from permanent stations within the Florida Keys National Marine Sanctuary (FKNMS), from both sides of the Florida Keys - two stations on the bay side and two stations on the reef side. These data will also help to constrain elements of the carbon and nitrogen cycles affecting this region. The data analyzed over the three year study period show unique cyclic trends associated with seasonal changes in primary productivity and potentially changes in the nitrogen and carbon pools. Additionally, the analysis of our time series indicates that isotope food web studies need to take into account spatial and temporal changes when evaluating trophic levels. The mean carbon and nitrogen isotope values of T. testudinum from all 4 stations vary respectively from -7.2 per mil to -10.41 and 1.1 per mil to 2.2 per mil (n = 48). However, certain stations displayed anonymously depleted nitrogen isotope values, values as low as -1.2 per mil. These values potentially indicated that biogeochmical processes like N fixation, ammonification and denitrification cause regional pattern in the isotopic composition of the source DIN. Both carbon and nitrogen isotopes displayed seasonal enrichment-depletion trends, with maximum enrichment occurring during the summer. The overall seasonal variation for carbon 13 from the different stations ranged from 1 per mil to

  19. Stable Carbon Isotope Fractionation during Bacterial Acetylene Fermentation: Potential for Life Detection in Hydrocarbon-Rich Volatiles of Icy Planet(oid)s

    OpenAIRE

    Miller, Laurence G.; Baesman, Shaun M.; Oremland, Ronald S.

    2015-01-01

    Abstract We report the first study of stable carbon isotope fractionation during microbial fermentation of acetylene (C2H2) in sediments, sediment enrichments, and bacterial cultures. Kinetic isotope effects (KIEs) averaged 3.7 ± 0.5‰ for slurries prepared with sediment collected at an intertidal mudflat in San Francisco Bay and 2.7 ± 0.2‰ for a pure culture of Pelobacter sp. isolated from these sediments. A similar KIE of 1.8 ± 0.7‰ was obtained for methanogenic enrichments derived from sedi...

  20. Stable isotopes of carbon dioxide in the marine atmosphere along a hemispheric course from China to Antarctica

    Science.gov (United States)

    Chen, Qingqing; Zhu, Renbin; Xu, Hua

    2013-12-01

    During the 24th Chinese Antarctic Expedition, the air samples were collected at 10:00 and 22:00 (local time) along the track of ship “Xuelong” from Shanghai Harbor, China to Antarctica. Carbon dioxide (CO2) concentrations and its isotopic compositions were measured in these samples. Mean CO2 concentration at 22:00 (419.4 ± 27.1 ppmv) was higher than that at 10:00 (392.7 ± 20.0 ppmv), whereas δ13C-CO2 values at 22:00 (-8.58 ± 0.47‰) were lower than those at 10:00 (-8.23 ± 0.49‰), indicating that the 13C/12C ratio might be associated with the photosynthesis and respiration of terrestrial or marine organisms during the diurnal cycle. Overall the mean δ13C- and δ18O-CO2 were -8.39 ± 0.51‰ and 0.03 ± 1.39‰, respectively, from 30°N to 69°S, and the δ13C significantly negatively correlated with δ18O-CO2. A small but progressive increase in δ13C values with increasing latitudes southward was in good agreement with the expected trend. The enhanced CO2 concentrations occurred in the atmosphere close to Eurasia continent, Philippines, Malaysia and Indonesia, and the δ13C oscillations agreed well with anthropogenic pollution. In the range of 30°S-50°S, CO2 concentrations were generally low with relatively stable δ13C and δ18O values. In Antarctic Convergence Zone, a great difference of δ13C occurred between 10:00 and 22:00, and atmospheric CO2 was significantly depleted in 13C at 22:00. Our results indicated that the isotopic compositions of CO2 in the marine atmosphere might be a sensitive indicator for the strength of CO2 source and sink from the ocean.

  1. Correlations Between Foliar Stable Carbon Isotope Composition and Environ-mental Factors in Desert Plant Reaumuria soongorica (Pall.) Maxim.

    Institute of Scientific and Technical Information of China (English)

    Jian-Ying MA; Tuo CHEN; Wei-Ya QIANG; Gang WANG

    2005-01-01

    Leaves of 407 individuals of Reaumuria soongorica (Pall.) Maxim. collected from the major distribution areas were measured to investigate the distribution characteristics of the stable carbon isotope in this desert plant, as well as correlations between δ13C values and environmental factors. Results showed that δ13C values in R. soongorica ranged from-22.77‰. to-29.85‰. and that the mean δ13C value (-26.52‰)was higher than a previously reported δ13C value for a different desert ecosystem. This indicates that R.soongorica belongs to the C3 photosynthetic pathway and has higher water use efficiency than other species. The correlations between δ13C values and environmental factors demonstrated that the foliar δ13C values in R. soongorica increased significantly with decreasing mean annual precipitation and mean relative humidity, and decreased with decreasing duration of sunshine and evaporation. The spatial distribution trend of δ13C values in R. soongorica was not obvious and there was no significant correlation between the δ13C values and mean annual temperature. We conclude that different distribution trends in δ13C values for R. soongorica were likely caused by stomatal limitation rather than by nutrient-related changes in photosynthetic efficiency and that precipitation played an important role in the wide distribution range of R.soongorica. This pattern of δ13C values for R. soongorica reinforced that it is a super-xerophil in terms of its adaptive strategies to a desert environment.

  2. 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

  3. Ubiquitous dissolved inorganic carbon assimilation by marine bacteria in the Pacific Northwest coastal ocean as determined by stable isotope probing.

    Directory of Open Access Journals (Sweden)

    Suzanne DeLorenzo

    Full Text Available In order to identify bacteria that assimilate dissolved inorganic carbon (DIC in the northeast Pacific Ocean, stable isotope probing (SIP experiments were conducted on water collected from 3 different sites off the Oregon and Washington coasts in May 2010, and one site off the Oregon Coast in September 2008 and March 2009. Samples were incubated in the dark with 2 mM (13C-NaHCO(3, doubling the average concentration of DIC typically found in the ocean. Our results revealed a surprising diversity of marine bacteria actively assimilating DIC in the dark within the Pacific Northwest coastal waters, indicating that DIC fixation is relevant for the metabolism of different marine bacterial lineages, including putatively heterotrophic taxa. Furthermore, dark DIC-assimilating assemblages were widespread among diverse bacterial classes. Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes dominated the active DIC-assimilating communities across the samples. Actinobacteria, Betaproteobacteria, Deltaproteobacteria, Planctomycetes, and Verrucomicrobia were also implicated in DIC assimilation. Alteromonadales and Oceanospirillales contributed significantly to the DIC-assimilating Gammaproteobacteria within May 2010 clone libraries. 16S rRNA gene sequences related to the sulfur-oxidizing symbionts Arctic96BD-19 were observed in all active DIC assimilating clone libraries. Among the Alphaproteobacteria, clones related to the ubiquitous SAR11 clade were found actively assimilating DIC in all samples. Although not a dominant contributor to our active clone libraries, Betaproteobacteria, when identified, were predominantly comprised of Burkholderia. DIC-assimilating bacteria among Deltaproteobacteria included members of the SAR324 cluster. Our research suggests that DIC assimilation is ubiquitous among many bacterial groups in the coastal waters of the Pacific Northwest marine environment and may represent a significant metabolic process.

  4. Technical Note: Constraining stable carbon isotope values of microphytobenthos (C3 photosynthesis) in the Arctic for application to food web studies

    Science.gov (United States)

    Oxtoby, L. E.; Mathis, J. T.; Juranek, L. W.; Wooller, M. J.

    2013-11-01

    Microphytobenthos (MPB) tends to be omitted as a possible carbon source to higher trophic level consumers in high latitude marine food web models that use stable isotopes. Here, we used previously published relationships relating the concentration of aqueous carbon dioxide ([CO2]aq), the stable carbon isotopic composition of dissolved inorganic carbon (DIC) (δ13CDIC), and algal growth rates (μ) to estimate the stable carbon isotope composition of MPB-derived total organic carbon (TOC) (δ13Cp) and fatty acid (FA) biomarkers (δ13CFA). We measured [CO2]aq and δ13CDIC values from bottom water at sampling locations in the Beaufort and Chukchi Seas (n = 18), which ranged from 17 to 72 mmol kg-1 and -0.1 to 1.4 ‰ (0.8 ± 0.4‰, mean ±1 s.d.), respectively. We combined these field measurements with a set of stable carbon isotopic fractionation factors reflecting differences in algal taxonomy and physiology to determine δ13Cp and δ13CFA values. Theδ13Cp and δ13CFA values for a mixed eukaryotic algal community were estimated to be -23.6 ± 0.4‰ and -30.6 ± 0.4‰, respectively. These values were similar to our estimates for Phaeodactylum tricornutum (δ13Cp = -23.9 ± 0.4‰, δ13CFA = -30.9 ± 0.4‰), a pennate diatom likely to be a dominant MPB taxon. Taxon-specific differences were observed between a centric diatom (Porosira glacialis, δ13Cp = -20.0 ± 1.6‰), a marine haptophyte (Emiliana huxleyi, δ13Cp = -22.7 ± 0.5‰), and a cyanobacterium (Synechococcus sp., δ13Cp = -16.2 ± 0.4‰) at μ = 0.1 d-1. δ13Cp and δ13CFA values increased by ≃ 2.5‰ for the mixed algal consortium and for P. tricornutum when growth rates were increased from 0.1 to 1.4 d-1. We compared our estimates of δ13Cp and δ13CFA values for MPB with previous measurements of δ13CTOC and δ13CFA values for other carbon sources in the Arctic, including ice-derived, terrestrial, and pelagic organic matter. We found that MPB values were significantly distinct from

  5. Automated determination of the stable carbon isotopic composition (δ13C) of total dissolved inorganic carbon (DIC) and total nonpurgeable dissolved organic carbon (DOC) in aqueous samples: RSIL lab codes 1851 and 1852

    Science.gov (United States)

    Révész, Kinga M.; Doctor, Daniel H.

    2014-01-01

    The purposes of the Reston Stable Isotope Laboratory (RSIL) lab codes 1851 and 1852 are to determine the total carbon mass and the ratio of the stable isotopes of carbon (δ13C) for total dissolved inorganic carbon (DIC, lab code 1851) and total nonpurgeable dissolved organic carbon (DOC, lab code 1852) in aqueous samples. The analysis procedure is automated according to a method that utilizes a total carbon analyzer as a peripheral sample preparation device for analysis of carbon dioxide (CO2) gas by a continuous-flow isotope ratio mass spectrometer (CF-IRMS). The carbon analyzer produces CO2 and determines the carbon mass in parts per million (ppm) of DIC and DOC in each sample separately, and the CF-IRMS determines the carbon isotope ratio of the produced CO2. This configuration provides a fully automated analysis of total carbon mass and δ13C with no operator intervention, additional sample preparation, or other manual analysis. To determine the DIC, the carbon analyzer transfers a specified sample volume to a heated (70 °C) reaction vessel with a preprogrammed volume of 10% phosphoric acid (H3PO4), which allows the carbonate and bicarbonate species in the sample to dissociate to CO2. The CO2 from the reacted sample is subsequently purged with a flow of helium gas that sweeps the CO2 through an infrared CO2 detector and quantifies the CO2. The CO2 is then carried through a high-temperature (650 °C) scrubber reactor, a series of water traps, and ultimately to the inlet of the mass spectrometer. For the analysis of total dissolved organic carbon, the carbon analyzer performs a second step on the sample in the heated reaction vessel during which a preprogrammed volume of sodium persulfate (Na2S2O8) is added, and the hydroxyl radicals oxidize the organics to CO2. Samples containing 2 ppm to 30,000 ppm of carbon are analyzed. The precision of the carbon isotope analysis is within 0.3 per mill for DIC, and within 0.5 per mill for DOC.

  6. Molecular marker and stable carbon isotope analyses of carbonaceous Ambassador uranium ores of Mulga Rock in Western Australia

    Science.gov (United States)

    Jaraula, C.; Schwark, L.; Moreau, X.; Grice, K.; Bagas, L.

    2013-12-01

    Mulga Rock is a multi-element deposit containing uranium hosted by Eocene peats and lignites deposited in inset valleys incised into Permian rocks of the Gunbarrel Basin and Precambrian rocks of the Yilgarn Craton and Albany-Fraser Orogen. Uranium readily adsorbs onto minerals or phytoclasts to form organo-uranyl complexes. This is important in pre-concentrating uranium in this relatively young ore deposit with rare uraninite [UO2] and coffinite [U(SiO4)1-x(OH)4x], more commonly amorphous and sub-micron uranium-bearing particulates. Organic geochemical and compound-specific stable carbon isotope analyses were conducted to identify possible associations of molecular markers with uranium accumulation and to recognize effect(s) of ionizing radiation on molecular markers. Samples were collected from the Ambassador deposit containing low (2000 ppm) uranium concentrations. The bulk rock C/N ratios of 82 to 153, Rock-Eval pyrolysis yields of 316 to 577 mg hydrocarbon/g TOC (Hydrogen Index, HI) and 70 to 102 mg CO2/g TOC (Oxygen Index, OI) are consistent with a terrigenous and predominantly vascular plant OM source deposited in a complex shallow water system, ranging from lacustrine to deltaic, swampy wetland and even shallow lake settings as proposed by previous workers. Organic solvent extracts were separated into saturated hydrocarbon, aromatic hydrocarbon, ketone, and a combined free fatty acid and alcohol fraction. The molecular profiles appear to vary with uranium concentration. In samples with relatively low uranium concentrations, long-chain n-alkanes, alcohols and fatty acids derived from epicuticular plant waxes dominate. The n-alkane distributions (C27 to C31) reveal an odd/even preference (Carbon Preference Index, CPI=1.5) indicative of extant lipids. Average δ13C of -27 to -29 ‰ for long-chain n-alkanes is consistent with a predominant C3 plant source. Samples with relatively higher uranium concentrations contain mostly intermediate-length n

  7. Detecting environmental change using stable isotopes

    International Nuclear Information System (INIS)

    Changing land use is one of the primary causes of increased sedimentation and nturient levels in aquqatic systems, resulting in contamiantion and reduction of biodiversity. Detecting and quantifying these inputs is the first step of remediation, to enable targeted reduction of transport processes into waterways from human impacted land surfaces. More recently, stable isotope analyses are being used as a detection and quantification tool in aquatic environments. Carbon and nitrogen isotopes of sediments, algae and invertebrates from aquatic systems can be used as proxies to record both short and long term enviornmental cahgne. Excess nutrients derived from urbanization, industry, forestry, farming and agriculture increase the bio-availability of nitrogen to aquatic organisms, changing their natural 15N isotopic signatures. Allochthonous (terrestrial) input from soil destabilization and human activity in surrounding catchments changes the 13C isotope ratios and increases the C:N ratio of sediments. Heavy metal and other organic pollutants can also be used to indicate urbanization and industrial contamination. The comined use of carbon and nitrogen isotopes, C:N ratios and heavy metals are powerful environmental monitoring tools which are useful indicators of source and transport pathways of terrestrial derive dmaterial and anthropogenic pollutants into streams, rivers and estuaries. (author). 56 refs., 10 figs., 3 tabs.

  8. Detecting environmental change using stable isotopes

    International Nuclear Information System (INIS)

    Changing land use is one of the primary causes of increased sedimentation and nutrient levels in aquatic systems, resulting in contamination and reduction of biodiversity. Detecting and quantifying these inputs is the first step of remediation, to enable targeted reduction of transport processes into waterways from human impacted land surfaces. More recently, stable isotope analyses are being used as a detection and quantification tool in aquatic environments. Carbon and nitrogen isotopes of sediments, algae and invertebrates from aquatic systems can be used as proxies to record both short and long term environmental change. Excess nutrients derived from urbanization, industry, forestry, farming and agriculture increase the bio-availability of nitrogen to aquatic organisms, changing their natural 15N isotopic signatures. Allochthonous (terrestrial) input from soil destabilization and human activity in surrounding catchments changes the 13C isotope ratios and increases the C:N ratio of sediments. Heavy metal and other organic pollutants can also be used to indicate urbanization and industrial contamination. The combined use of carbon and nitrogen isotopes, C:N ratios and heavy metals are powerful environmental monitoring tools which are useful indicators of source and transport pathways of terrestrial derived material and anthropogenic pollutants into streams, rivers and estuaries. (author).

  9. Arctic cisco stable isotope data, Prudhoe Bay, August 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set documents the carbon and nitrogen stable isotope ratios of age-0 Arctic cisco (Coregonus autumnalis) captured in Prudhoe Bay, Alaska in August 2009....

  10. Fate of process solution cyanide and nitrate at three nevada gold mines inferred from stable carbon and nitrogen isotope measurements

    Science.gov (United States)

    Johnson, C.A.; Grimes, D.J.; Rye, R.O.

    2000-01-01

    Stable isotope methods have been used to identify the mechanisms responsible for cyanide consumption at three heap-leach operations that process Carlin-type gold ores in Nevada, U.S.A. The reagent cyanide had ??15N values ranging from -5 to -2??? and ??13C values from -60 to -35???. The wide ??13C range reflects the use by different suppliers of isotopically distinct natural-gas feedstocks and indicates that isotopes may be useful in environmental studies where there is a need to trace cyanide sources. In heap-leach circuits displaying from 5 to 98% consumption of cyanide, barren-solution and pregnant-solution cyanide were isotopically indistinguishable. The similarity is inconsistent with cyanide loss predominantly by HCN offgassing (a process that in laboratory experiments caused substantial isotopic changes), but it is consistent with cyanide retention within the heaps as solids, a process that caused minimal isotopic changes in laboratory simulations, or with cyanide oxidation, which also appears to cause minimal changes. In many pregnant solutions cyanide was carried entirely as metal complexes, which is consistent with ferrocyanides having precipitated or cyanocomplexes having been adsorbed within the heaps. It is inferred that gaseous cyanide emissions from operations of this type are less important than has generally been thought and that the dissolution or desorption kinetics of solid species is an important control on cyanide elution when the spent heaps undergo rinsing. Nitrate, nitrite and ammonium had ??15N values of 1-16???. The data reflect isotopic fractionation during ammonia offgassing or denitrification of nitrate - particularly in reclaim ponds - but do not indicate the extent to which nitrate is derived from cyanide or from explosive residues. ?? The Institution of Mining and Metallurgy 2000.

  11. Non-linear dynamics of stable carbon and hydrogen isotope signatures based on a biological kinetic model of aerobic enzymatic methane oxidation.

    Science.gov (United States)

    Vavilin, Vasily A; Rytov, Sergey V; Shim, Natalia; Vogt, Carsten

    2016-06-01

    The non-linear dynamics of stable carbon and hydrogen isotope signatures during methane oxidation by the methanotrophic bacteria Methylosinus sporium strain 5 (NCIMB 11126) and Methylocaldum gracile strain 14 L (NCIMB 11912) under copper-rich (8.9 µM Cu(2+)), copper-limited (0.3 µM Cu(2+)) or copper-regular (1.1 µM Cu(2+)) conditions has been described mathematically. The model was calibrated by experimental data of methane quantities and carbon and hydrogen isotope signatures of methane measured previously in laboratory microcosms reported by Feisthauer et al. [ 1 ] M. gracile initially oxidizes methane by a particulate methane monooxygenase and assimilates formaldehyde via the ribulose monophosphate pathway, whereas M. sporium expresses a soluble methane monooxygenase under copper-limited conditions and uses the serine pathway for carbon assimilation. The model shows that during methane solubilization dominant carbon and hydrogen isotope fractionation occurs. An increase of biomass due to growth of methanotrophs causes an increase of particulate or soluble monooxygenase that, in turn, decreases soluble methane concentration intensifying methane solubilization. The specific maximum rate of methane oxidation υm was proved to be equal to 4.0 and 1.3 mM mM(-1) h(-1) for M. sporium under copper-rich and copper-limited conditions, respectively, and 0.5 mM mM(-1) h(-1) for M. gracile. The model shows that methane oxidation cannot be described by traditional first-order kinetics. The kinetic isotope fractionation ceases when methane concentrations decrease close to the threshold value. Applicability of the non-linear model was confirmed by dynamics of carbon isotope signature for carbon dioxide that was depleted and later enriched in (13)C. Contrasting to the common Rayleigh linear graph, the dynamic curves allow identifying inappropriate isotope data due to inaccurate substrate concentration analyses. The non-linear model pretty adequately described experimental

  12. Palaeoclimate interpretation of stable isotope data from lake sediment archives

    OpenAIRE

    Leng, Melanie J.; Marshall, Jim D.

    2004-01-01

    The isotope composition of authigenic and biogenic carbonates and diatom silica are commonly used as palaeoclimate proxies from lake sediments. This article reviews the controls on the isotope composition of lacustrine skeletal and non-skeletal deposits and illustrates how stable isotope studies contribute to an understanding of changes in temperature, precipitation patterns, evaporation and the carbon cycle. It highlights the differences in the palaeoclimate potential of a wide range of lake...

  13. In Situ Carbon Stable Isotope Tracer Experiments Elucidate Carbon Translocation Rates and Allocation Patterns in Zostera marina L. (eelgrass)

    Science.gov (United States)

    The intertidal seagrass Zostera marina is an important species that provides critical habitat for a number of estuarine species. Despite its widespread distribution, there is limited information on seasonal patterns of carbon dynamics of plants growing in situ, particularly esti...

  14. Improved constraints on in situ rates and on quantification of complete chloroethene degradation from stable carbon isotope mass balances in groundwater plumes

    Science.gov (United States)

    Höhener, Patrick; Elsner, Martin; Eisenmann, Heinrich; Atteia, Olivier

    2015-11-01

    Spills of chloroethenes (CEs) at industrial and urban sites can create groundwater plumes in which tetrachloro- and trichloroethene sequentially degrade to dichloroethenes, vinyl chloride (VC) and ethene, or ethane under reducing conditions. For detoxification, degradation must go beyond VC. Assessments based on ethene and ethane, however, are difficult because these products are volatile, may stem from alternative sources, can be further transformed and are not always monitored. To alternatively quantify degradation beyond VC, stable carbon isotope mass balances have been proposed where concentration-weighted CE isotope ratios are summed up and compared to the original source isotope ratio. Reported assessments, however, have provided not satisfactorily quantified results entailing greatly differing upper and lower estimates. This work proposes an integrative approach to better constrain the extent of total chloroethene degradation in groundwater samples. It is based on fitting of measured concentration and compound-specific stable carbon isotope data to an analytical reactive transport equation simulating steady-state plumes in two dimensions using an EXCEL spreadsheet. The fitting also yields estimates of degradation rates, of source width and of dispersivities. The approach is validated using two synthetic benchmark cases where the true extent of degradation is well known, and using data from two real field cases from literature.

  15. High resolution stable isotope and carbonate variability during the early Oligocene climate transition: Walvis Ridge (ODP Site 1263)

    Science.gov (United States)

    2007-01-01

    The rapid global increase in benthic foraminiferal δ18O in the early Oligocene (~33.6 Ma) has been taken to imply the first appearance of large, permanent ice sheets on Antarctica, possibly coupled to deep sea cooling and/or Northern Hemisphere ice growth. This oxygen isotope shift is accompanied by a reorganization of the global carbon cycle, identified by a δ13C increase that slightly lags the glacially-mediated δ18O transition. Here, we present a new

  16. Differential processing of anthropogenic carbon and nitrogen in benthic food webs of A Coruña (NW Spain) traced by stable isotopes

    Science.gov (United States)

    Bode, Antonio; Fernández, Consolación; Mompeán, Carmen; Parra, Santiago; Rozada, Fernando; Valencia-Vila, Joaquín; Viana, Inés G.

    2014-08-01

    In this study the effect of inputs of organic matter and anthropogenic nitrogen at small spatial scales were investigated in the benthos of the Ria of A Coruña (NW Spain) using stable carbon and nitrogen isotopes. This ria is characteristically enriched in nutrients provided either by marine processes (as coastal upwelling) or by urban and agricultural waste. Stable isotope composition in trophic guilds of infaunal benthos revealed spatial differences related to their nutrient inputs. The main difference was the presence of an additional chemoautotrophic food web at the site with a large accumulation of organic matter. The enrichment in heavy nitrogen isotopes observed in most compartments suggests the influence of sewage-derived nitrogen, despite large inputs of marine nitrogen. Macroalgae (Fucus vesiculosus) resulted significantly enriched at the site influenced by estuarine waters. In contrast, no differences were found in mussels (Mytilus galloprovincialis), thus suggesting a major dependence on marine nutrient sources for this species. However, the estimations of anthropogenic influence were largely dependent on assumptions required to model the different contributions of sources. The measurement of stable isotope signatures in various compartments revealed that, despite anthropogenic nutrients are readily incorporated into local food webs, a major influence of natural marine nutrient sources cannot be discarded.

  17. Stable isotopes and biomarkers in microbial ecology

    NARCIS (Netherlands)

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

    2002-01-01

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

  18. Recycling of water, carbon, and sulfur during subduction of serpentinites: A stable isotope study of Cerro del Almirez, Spain

    Science.gov (United States)

    Alt, Jeffrey C.; Garrido, Carlos J.; Shanks, Wayne C.; Turchyn, Alexandra; Padrón-Navarta, José Alberto; López Sánchez-Vizcaíno, Vicente; Gómez Pugnaire, María Teresa; Marchesi, Claudio

    2012-01-01

    We use the concentrations and isotope compositions of water, carbon, and sulfur in serpentinites and their dehydration products to trace the cycling of volatiles during subduction. Antigorite serpentinites from the Cerro del Almirez complex, Spain, contain 9–12 wt.% H2O and 910 ± 730 ppm sulfur, and have bulk δ18O values of 8.6 ± 0.4‰, δD = − 54 ± 5‰, and δ34S = 5.0‰, consistent with serpentinization at temperatures of ~ 200 °C by seawater hydrothermal fluids in a seafloor setting. The serpentinites were dehydrated to chlorite–harzburgite (olivine + orthopyroxene + chlorite) at 700 °C and 1.6–1.9 GPa during subduction metamorphism, resulting in loss of water, and sulfur. The chlorite–harzburgites contain 5.7 ± 1.9 wt.% H2O, and have bulk δ18O = 8.0 ± 0.9‰, and δD = − 77 ± 11‰. The rocks contain 650 ± 620 ppm sulfur having δ34S = 1.2‰. Dehydration of serpentinite resulted in loss of 5 wt.% H2O having δ18O = 8–10‰ and δD = − 27 to − 65‰, and loss of 260 ppm sulfur as sulfate, having δ34S = 14.5‰. The contents and δ13C of total carbon in the two rock types overlap, with a broad trend of decreasing carbon contents and δ13C from ~ 1300 to 200 ppm and − 9.6 to − 20.2‰. This reflects mixing between reduced carbon in the rocks (210 ppm, δ13C ≈ − 26‰) and seawater-derived carbonate (δ13C ≈ − 1‰). Our results indicate: 1) Serpentinized oceanic peridotites carry significant amounts of isotopically fractionated water, carbon and sulfur into subduction zones; 2) Subduction of serpentinites to high P and T results in loss of water, and sulfur, which can induce melting and contribute to 18O, D, and 34S enrichments and oxidation of the sub-arc mantle wedge; and 3) Isotopically fractionated water, carbon, and sulfur in serpentinite dehydration products are recycled deeper into the mantle where they can contribute to isotope heterogeneities and may be significant for volatile budgets of the deep Earth.

  19. Influences on the stable oxygen and carbon isotopes in gerbillid rodent teeth in semi-arid and arid environments: Implications for past climate and environmental reconstruction

    Science.gov (United States)

    Jeffrey, Amy; Denys, Christiane; Stoetzel, Emmanuelle; Lee-Thorp, Julia A.

    2015-10-01

    The stable isotope composition of small mammal tissues has the potential to provide detailed information about terrestrial palaeoclimate and environments, because their remains are abundant in palaeontological and archaeological sites, and they have restricted home ranges. Applications to the Quaternary record, however, have been sparse and limited by an acute lack of understanding of small mammal isotope ecology, particularly in arid and semi-arid environments. Here we document the oxygen and carbon isotope composition of Gerbillinae (gerbil) tooth apatite across a rainfall gradient in northwestern Africa, in order to test the relative influences of the 18O/16O in precipitation or moisture availability on gerbil teeth values, the sensitivity of tooth apatite 13C/12C to plant responses to moisture availability, and the influence of developmental period on the isotopic composition of gerbil molars and incisors. The results show that the isotopic composition of molars and incisors from the same individuals differs consistent with the different temporal periods reflected by the teeth; molar teeth are permanently rooted and form around the time of birth, whereas incisors grow continuously. The results indicate that tooth choice is an important consideration for applications as proxy Quaternary records, but also highlights a new potential means to distinguish seasonal contexts. The oxygen isotope composition of gerbil tooth apatite is strongly correlated with mean annual precipitation (MAP) below 600 mm, but above 600 mm the teeth reflect the oxygen isotope composition of local meteoric water instead. Predictably, the carbon isotope composition of the gerbil teeth reflected C3 and C4 dietary inputs, however arid and mesic sites could not be distinguished because of the high variability displayed in the carbon isotope composition of the teeth due to the microhabitat and short temporal period reflected by the gerbil. We show that the oxygen isotope composition of small

  20. A reconstruction of atmospheric carbon dioxide and its stable carbon isotopic composition from the penultimate glacial maximum to the last glacial inception

    Directory of Open Access Journals (Sweden)

    R. Schneider

    2013-11-01

    δ13Catm level in the Penultimate (~ 140 000 yr BP and Last Glacial Maximum (~ 22 000 yr BP, which can be explained by either (i changes in the isotopic composition or (ii intensity of the carbon input fluxes to the combined ocean/atmosphere carbon reservoir or (iii by long-term peat buildup. Our isotopic data suggest that the carbon cycle evolution along Termination II and the subsequent interglacial was controlled by essentially the same processes as during the last 24 000 yr, but with different phasing and magnitudes. Furthermore, a 5000 yr lag in the CO2 decline relative to EDC temperatures is confirmed during the glacial inception at the end of MIS5.5 (120 000 yr BP. Based on our isotopic data this lag can be explained by terrestrial carbon release and carbonate compensation.

  1. 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)

  2. Atmospheric carbon dioxide and its stable isotope ratios, methane, carbon monoxide, nitrous oxide and hydrogen from Shetland Isles

    Science.gov (United States)

    Francey, R. J.; Steele, L. P.; Langenfelds, R. L.; Allison, C. E.; Cooper, L. N.; Dunse, B. L.; Bell, B. G.; Murray, T. D.; Tait, H. S.; Thompson, L.; Masarie, K. A.

    Since November 1992, 0.5 l glass flasks have been filled approximately monthly with dry marine air from Shetland Isles, Scotland (60.2°N, 1.2°W) and transported to CSIRO, Australia for analyses. The Shetland site is part of a CSIRO global flask network with 10-12 sites, anchored to continuous high precision in situ measurements made at the Australian Cape Grim Baseline Station (40.7°S, 144.7°E), a primary station in the Global Atmosphere Watch programme (GAW) coordinated by the World Meteorological Organisation. The methodology is summarised, and Shetland results for CO 2, CH 4, N 2O, CO, H 2 and δ13C, δ18O of CO 2 presented for the period 1992-1996. We compare data to available results from surrounding stations of the NOAA cooperative network (in particular Mace Head, Ireland, 53.3°N, 9.9°W), and address issues of both trace species intercalibration and atmospheric spatial gradients. While considerable uniformity of trace-gas composition is evident in oceanic air over a 13° range of latitude, nevertheless anomalies in CO 2 concentration and isotopic composition are suggested in samples representing air to the west of Shetland. The potential for remotely monitoring integrated emissions from northern Europe is also identified.

  3. Stable carbon isotopes of C3 plant resins and ambers record changes in atmospheric oxygen since the Triassic

    Science.gov (United States)

    Tappert, Ralf; McKellar, Ryan C.; Wolfe, Alexander P.; Tappert, Michelle C.; Ortega-Blanco, Jaime; Muehlenbachs, Karlis

    2013-11-01

    Estimating the partial pressure of atmospheric oxygen (pO2) in the geological past has been challenging because of the lack of reliable proxies. Here we develop a technique to estimate paleo-pO2 using the stable carbon isotope composition (δ13C) of plant resins-including amber, copal, and resinite-from a wide range of localities and ages (Triassic to modern). Plant resins are particularly suitable as proxies because their highly cross-linked terpenoid structures allow the preservation of pristine δ13C signatures over geological timescales. The distribution of δ13C values of modern resins (n = 126) indicates that (a) resin-producing plant families generally have a similar fractionation behavior during resin biosynthesis, and (b) the fractionation observed in resins is similar to that of bulk plant matter. Resins exhibit a natural variability in δ13C of around 8‰ (δ13C range: -31‰ to -23‰, mean: -27‰), which is caused by local environmental and ecological factors (e.g., water availability, water composition, light exposure, temperature, nutrient availability). To minimize the effects of local conditions and to determine long-term changes in the δ13C of resins, we used mean δ13C values (δ13Cmeanresin) for each geological resin deposit. Fossil resins (n = 412) are generally enriched in 13C compared to their modern counterparts, with shifts in δ13Cmeanresin of up to 6‰. These isotopic shifts follow distinctive trends through time, which are unrelated to post-depositional processes including polymerization and diagenesis. The most enriched fossil resin samples, with a δ13Cmeanresin between -22‰ and -21‰, formed during the Triassic, the mid-Cretaceous, and the early Eocene. Experimental evidence and theoretical considerations suggest that neither change in pCO2 nor in the δ13C of atmospheric CO2 can account for the observed shifts in δ13Cmeanresin. The fractionation of 13C in resin-producing plants (Δ13C), instead, is primarily influenced by

  4. Method for the isolation of citric acid and malic acid in Japanese apricot liqueur for carbon stable isotope analysis.

    Science.gov (United States)

    Akamatsu, Fumikazu; Hashiguchi, Tomokazu; Hisatsune, Yuri; Oe, Takaaki; Kawao, Takafumi; Fujii, Tsutomu

    2017-02-15

    A method for detecting the undeclared addition of acidic ingredients is required to control the authenticity of Japanese apricot liqueur. We developed an analytical procedure that minimizes carbon isotope discrimination for measurement of the δ(13)C values of citric and malic acid isolated from Japanese apricot liqueur. Our results demonstrated that freeze-drying is preferable to nitrogen spray-drying, because it does not significantly affect the δ(13)C values of citric acid and results in smaller isotope discrimination for malic acid. Both 0.1% formic acid and 0.2% phosphoric acid are acceptable HPLC mobile phases for the isolation of citric and malic acid, although the δ(13)C values of malic acid exhibited relatively large variation compared with citric acid following isolation using either mobile phase. The developed procedure allows precise δ(13)C measurements of citric and malic acid isolated from Japanese apricot liqueur. PMID:27664615

  5. Radiocarbon and stable carbon isotope compositions of chemically fractionated soil organic matter in a temperate-zone forest

    International Nuclear Information System (INIS)

    To better understand the role of soil organic matter in terrestrial carbon cycle, carbon isotope compositions in soil samples from a temperate-zone forest were measured for bulk, acid-insoluble and base-insoluble organic matter fractions separated by a chemical fractionation method. The measurements also made it possible to estimate indirectly radiocarbon (14C) abundances of acid- and base-soluble organic matter fractions, through a mass balance of carbon among the fractions. The depth profiles of 14C abundances showed that (1) bomb-derived 14C has penetrated the first 16 cm mineral soil at least; (2) Δ14C values of acid-soluble organic matter fraction are considerably higher than those of other fractions; and (3) a significant amount of the bomb-derived 14C has been preserved as the base-soluble organic matter around litter-mineral soil boundary. In contrast, no or little bomb-derived 14C was observed for the base-insoluble fraction in all sampling depths, indicating that this recalcitrant fraction, accounting for approximately 15% of total carbon in this temperate-zone forest soil, plays a role as a long-term sink in the carbon cycle. These results suggest that bulk soil organic matter cannot provide a representative indicator as a source or a sink of carbon in soil, particularly on annual to decadal timescales

  6. ASE extraction method for simultaneous carbon and nitrogen stable isotope analysis in soft tissues of aquatic organisms

    Energy Technology Data Exchange (ETDEWEB)

    Bodin, Nathalie [ISM/LPTC, UMR 5255 CNRS, Universite de Bordeaux 1, 351 Cours de la Liberation, 33405 Talence (France); CRH, UMR 212 EME, Institut de Recherche et de Developpement, Av Jean Monnet BP171, 34203 Sete (France); Budzinski, Helene, E-mail: h.budzinski@ism.u-bordeaux1.fr [ISM/LPTC, UMR 5255 CNRS, Universite de Bordeaux 1, 351 Cours de la Liberation, 33405 Talence (France); Le Menach, Karyn; Tapie, Nathalie [ISM/LPTC, UMR 5255 CNRS, Universite de Bordeaux 1, 351 Cours de la Liberation, 33405 Talence (France)

    2009-06-08

    Since lipids are depleted in {sup 13}C relative to proteins and carbohydrates, variations in lipid composition among species and within individuals significantly influence {delta}{sup 13}C and may result in misleading ecological interpretations. Whereas lipid extraction before IRMS analysis constitutes a way of stable isotope result lipid-normalisation, such a procedure was given up because of the un-controlled effects of the methods used (i.e., 'Bligh and Dyer', Soxhlet, etc.) on {delta}{sup 15}N. The aim of this work was to develop a simple, rapid and efficient lipid extraction method allowing for simultaneous C and N stable isotope analysis in the biological soft tissues of aquatic organisms. The goal was to be free from the lipid influence on {delta}{sup 13}C values without interfering with {delta}{sup 15}N values. For that purpose, the modern automated pressurized liquid extraction technique ASE (accelerated solvent extraction) was selected. Eel muscles representative of a broad range of fat contents were extracted via ASE by using different semi-polar solvents (100% dichloromethane and 80% n-hexane/20% acetone) and by operating at different temperature (ambient temperature and 100 deg. C) and pressure (750 and 1900 psi) conditions. The results were discussed in terms of lipid extraction efficiency as well as {delta}{sup 13}C and {delta}{sup 15}N variability.

  7. Stable isotope sales: Mound customer and shipment summaries, FY 1982

    International Nuclear Information System (INIS)

    A listing is given of Mound's sales of stable isotopes of noble gases, carbon, oxygen, nitrogen, chlorine, and sulfur for Fiscal Year 1982. Purchasers are listed alphabetically and are divided into domestic and foreign groups. A cross-reference index by location is included for domestic customers. Cross-reference listings by isotope purchased are included for all customers

  8. Stable isotope sales: Mound customer and shipment summaries, FY 1984

    International Nuclear Information System (INIS)

    A listing is given of Mound's sales of stable isotopes of noble gases, deuterium, carbon, oxygen, nitrogen, chlorine, bromine, and sulfur for Fiscal Year 1984. Purchasers are listed alphabetically and are divided into domestic and foreign groups. A cross-reference index by location and a cross-reference listing by isotope purchased are included for all customers

  9. Stable isotopes sales: Mound customer and shipment summaries, FY 1985

    International Nuclear Information System (INIS)

    A listing is given of Mound's sales of stable isotopes of noble gases, deuterium, carbon, oxygen, nitrogen, chlorine, bromine, and sulfur for fiscal year 1985. Purchasers are listed alphabetically and are divided into domestic and foreign groups. A cross-reference index by location is included for domestic and foreign customers. Cross-reference listings by isotope purchased are included for all customers

  10. USE OF STABLE ISOTOPES IN ENVIRONMENTAL AND FORENSIC GEOCHEMISTRY STUDIES

    Science.gov (United States)

    Stable carbon and hydrogen isotopes have been used for many decades in the petroleum industry, but the development of combined gas chromatography-isotope ratio mass spectrometry (GCIRMS) has led to a virtual explosion in application of this technique not only in petroleum explora...

  11. 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 ...

  12. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems

    OpenAIRE

    Lepoint, Gilles; Dauby, Patrick; Gobert, Sylvie

    2004-01-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure o...

  13. Assessing the Utility of Hydrogen, Carbon and Nitrogen Stable Isotopes in Estimating Consumer Allochthony in Two Shallow Eutrophic Lakes.

    Directory of Open Access Journals (Sweden)

    Jari Syväranta

    Full Text Available Hydrogen stable isotopes (δ2H have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potential variation in the amount of exchangeable hydrogen (Hex among common sample materials or the patterns of δ2H when entire food webs are considered. We assessed differences in Hex among the typical sample materials in freshwater studies and used δ2H, δ13C and δ15N to compare their effectiveness in tracing allochthonous matter in food webs of two small temperate lakes. Our results showed higher average amounts of Hex in animal tissues (27% in fish and macroinvertebrates, 19% in zooplankton compared to most plant material (15% in terrestrial plants and 8% in seston/periphyton, with the exception of aquatic vascular plants (23%, referred to as macrophytes. The amount of Hex correlated strongly with sample lipid content (inferred from C:N ratios in fish and zooplankton samples. Overall, the three isotopes provided good separation of sources (seston, periphyton, macrophytes and allochthonous organic matter, particularly the δ2H followed by δ13C. Aquatic macrophytes revealed unexpectedly high δ2H values, having more elevated δ2H values than terrestrial organic matter with direct implications for estimating consumer allochthony. Organic matter from macrophytes significantly contributed to the food webs in both lakes highlighting the need to include macrophytes as a potential source when using stable isotopes to estimate trophic structures and contributions from allochthonous sources.

  14. Assessing the Utility of Hydrogen, Carbon and Nitrogen Stable Isotopes in Estimating Consumer Allochthony in Two Shallow Eutrophic Lakes.

    Science.gov (United States)

    Syväranta, Jari; Scharnweber, Kristin; Brauns, Mario; Hilt, Sabine; Mehner, Thomas

    2016-01-01

    Hydrogen stable isotopes (δ2H) have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potential variation in the amount of exchangeable hydrogen (Hex) among common sample materials or the patterns of δ2H when entire food webs are considered. We assessed differences in Hex among the typical sample materials in freshwater studies and used δ2H, δ13C and δ15N to compare their effectiveness in tracing allochthonous matter in food webs of two small temperate lakes. Our results showed higher average amounts of Hex in animal tissues (27% in fish and macroinvertebrates, 19% in zooplankton) compared to most plant material (15% in terrestrial plants and 8% in seston/periphyton), with the exception of aquatic vascular plants (23%, referred to as macrophytes). The amount of Hex correlated strongly with sample lipid content (inferred from C:N ratios) in fish and zooplankton samples. Overall, the three isotopes provided good separation of sources (seston, periphyton, macrophytes and allochthonous organic matter), particularly the δ2H followed by δ13C. Aquatic macrophytes revealed unexpectedly high δ2H values, having more elevated δ2H values than terrestrial organic matter with direct implications for estimating consumer allochthony. Organic matter from macrophytes significantly contributed to the food webs in both lakes highlighting the need to include macrophytes as a potential source when using stable isotopes to estimate trophic structures and contributions from allochthonous sources.

  15. Traceability of animal byproducts in quail (Coturnix coturnix japonica tissues using carbon (13C/12C and nitrogen (15N/14N stable isotopes

    Directory of Open Access Journals (Sweden)

    C Móri

    2007-12-01

    Full Text Available Consistent information on meat products consumed by the public is essential. The technique of stable isotopes is a powerful tool to recover consumers' confidence, as it allows the detection of animal byproduct residues in poultry meat, particularly in quail meat. This study aimed at checking the presence of poultry byproduct mixtures in quail diets by applying the technique of carbon (13C/12C and nitrogen (15N/14N stable isotopes in quail breast muscle, keel, and tibia. Sixty four one-day-old male quails were obtained from a commercial farm. Birds were housed in an experimental house from one to 42 days of age, and were randomly distributed into 8 experimental treatments, and fed diets containing poultry offal meal (POM, bovine meat and bone meal (MBM or poultry feather meal (PFM, or their mixtures. Four birds per treatment were slaughtered at 42 days of age, and breast (Pectoralis major, keel, and tibia were collected for analyses. The inclusion of animal byproducts in quail diets was detected by 13C e 15N analyses in the tissues of the birds; however, it was not possible to specify which byproducts were used. It was concluded that quail meat can be certified by the technique of stable isotopes.

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

    Science.gov (United States)

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

    2016-04-01

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

  17. Using Stable Isotopes of Carbon and Nitrogen to Mark Wild Populations of Anopheles and Aedes Mosquitoes in South-Eastern Tanzania

    Science.gov (United States)

    Opiyo, Mercy A.; Hamer, Gabriel L.; Lwetoijera, Dickson W.; Auckland, Lisa D.; Majambere, Silas; Okumu, Fredros O.

    2016-01-01

    Background Marking wild mosquitoes is important for understanding their ecology, behaviours and role in disease transmission. Traditional insect marking techniques include using fluorescent dyes, protein labels, radioactive labels and tags, but such techniques have various limitations; notably low marker retention and inability to mark wild mosquitoes at source. Stable isotopes are gaining wide spread use for non-invasive marking of arthropods, permitting greater understanding of mosquito dispersal and responses to interventions. We describe here a simple technique for marking naturally-breeding malaria and dengue vectors using stable isotopes of nitrogen (15N) and carbon (13C), and describe potential field applications. Methods We created man-made aquatic mosquito habitats and added either 15N-labelled potassium nitrate or 13C-labelled glucose, leaving non-adulterated habitats as controls. We then allowed wild mosquitoes to lay eggs in these habitats and monitored their development in situ. Pupae were collected promptly as they appeared and kept in netting cages. Emergent adults (in pools of ~4 mosquitoes/pool) and individually stored pupae were desiccated and analysed using Isotope Ratio Mass Spectrometry (IRMS). Findings Anopheles gambiae s.l and Aedes spp. from enriched 13C and enriched 15N larval habitats had significantly higher isotopic levels than controls (P = 0.005), and both isotopes produced sufficient distinction between marked and unmarked mosquitoes. Mean δ15N for enriched females and males were 275.6±65.1 and 248.0±54.6, while mean δ15N in controls were 2.1±0.1 and 3.9±1.7 respectively. Similarly, mean δ13C for enriched females and males were 36.08±5.28 and 38.5±6.86, compared to -4.3±0.2 and -7.9±3.6 in controls respectively. Mean δ15N and δ13C was significantly higher in any pool containing at least one enriched mosquito compared to pools with all unenriched mosquitoes, P<0.001. In all cases, there were variations in standardized

  18. Carbon dioxide effects research and assessment program. Proceedings of the International Meeting on Stable Isotopes in Tree-Ring Research, New Paltz, New York, May 22-25, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Jacoby, G [ed.

    1980-12-01

    Information about the past and present concentrations of CO/sub 2/ in the atmosphere and variations in climate can be obtained from measurements of stable isotopes in tree rings; specifically carbon-13, oxygen-18 and deuterium. The analysis of these stable isotopes in tree rings is a relatively new and rapidly developing field. This proceedings volume contains most of the papers presented at the meeting. The first paper gives an overview of the status of carbon-13 research. Papers relating to carbon-13 are in section I and grouped separately from the contributions on carbon-14. Although the meeting was primarily concerned with stable isotopes, all carbon isotopic analysis may be helpful in understanding the carbon-13 record in tree rings. The papers on hydrogen and oxygen isotope studies are in sections II and III respectively. The remaining sections contain papers that consider more than one isotope at a time, general topics related to isotopes, atmospheric changes and tree growth, and methods of isotopic analysis.

  19. Stable isotopic analyses in paleoclimatic reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Wigand, P.E. [Univ. and Community College System of Nevada, Reno, NV (United States)

    1995-09-01

    Most traditional paleoclimatic proxy data have inherent time lags between climatic input and system response that constrain their use in accurate reconstruction of paleoclimate chronology, scaling of its variability, and the elucidation of the processes that determine its impact on the biotic and abiotic environment. With the exception of dendroclimatology, and studies of short-lived organisms and pollen recovered from annually varved lacustrine sediments, significant periods of time ranging from years, to centuries, to millennia may intervene between climate change and its first manifestation in paleoclimatic proxy data records. Reconstruction of past climate through changes in plant community composition derived from pollen sequences and plant remains from ancient woodrat middens, wet environments and dry caves all suffer from these lags. However, stable isotopic analyses can provide more immediate indication of biotic response to climate change. Evidence of past physiological response of organisms to changes in effective precipitation as climate varies can be provided by analyses of the stable isotopic content of plant macrofossils from various contexts. These analyses consider variation in the stable isotopic (hydrogen, oxygen and carbon) content of plant tissues as it reflects (1) past global or local temperature through changes in meteoric (rainfall) water chemistry in the case of the first two isotopes, and (2) plant stress through changes in plant respiration/transpiration processes under differing water availability, and varying atmospheric CO, composition (which itself may actually be a net result of biotic response to climate change). Studies currently being conducted in the Intermountain West indicate both long- and short-term responses that when calibrated with modem analogue studies have the potential of revealing not only the timing of climate events, but their direction, magnitude and rapidity.

  20. Stable carbon isotope fractionation of trans-1,2-dichloroethylene during co-metabolic degradation by methanotrophic bacteria

    Science.gov (United States)

    Brungard, K.L.; Munakata-Marr, J.; Johnson, C.A.; Mandernack, K.W.

    2003-01-01

    Changes in the carbon isotope ratio (??13C) of trans-1,2-dichloroethylene (t-DCE) were measured during its co-metabolic degradation by Methylomonas methanica, a type I methanotroph, and Methylosinus trichosporium OB3b, a type II methanotroph. In closed-vessel incubation experiments with each bacterium, the residual t-DCE became progressively enriched in 13C, indicating isotopic fractionation. From these experiments, the biological fractionation during t-DCE co-metabolism, expressed as ??, was measured to be -3.5??? for the type I culture and -6.7??? for the type II culture. This fractionation effect and subsequent enrichment in the ??13C of the residual t-DCE can thus be applied to determine the extent of biodegradation of DCE by these organisms. Based on these results, isotopic fractionation clearly warrants further study, as measured changes in the ??13C values of chlorinated solvents could ultimately be used to monitor the extent of biodegradation in laboratory or field settings where co-metabolism by methanotrophs occurs. ?? 2002 Elsevier Science B.V. All rights reserved.

  1. Soil organic carbon dynamics under long-term fertilization in a black soil of China: Evidence from stable C isotopes

    Science.gov (United States)

    Dou, Xiaolin; He, Ping; Zhu, Ping; Zhou, Wei

    2016-01-01

    Effects of different fertilizers on organic carbon (C) storage and turnover of soil fractions remains unclear. We combined soil fractionation with isotope analyses to examine soil organic carbon (SOC) dynamics after 25 years of fertilization. Five types of soil samples including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, N; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into four aggregate sizes (>2000 μm, 2000–250 μm, 250–53 μm, and 250 μm aggregates but reduced SOC storage in <250 μm aggregates due to SOC changes in LF and iPOM. PMID:26898121

  2. Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions

    Directory of Open Access Journals (Sweden)

    B. He

    2010-04-01

    Full Text Available Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized by a variety of techniques, including elemental (C and N, stable carbon isotopic13C composition, as well as molecular-level analyses. Total organic carbon (TOC content was 1.61±1.20% in the upper reach down to 1.00±0.22% in Lingdingyang Bay and to 0.80±0.10% on the inner shelf and 0.58±0.06% on the outer shelf. δ13C values ranged from −25.11‰ to −21.28‰ across the studied area, with a trend of enrichment seaward. The spatial trend in C/N ratios mirrored that of δ13C, with a substantial decrease in C/N ratio from 10.9±1.3 in the Lingdingyang Bay surface sediments to 6.5±0.09 in the outer shelf surface sediments. Total carbohydrate yields ranged from 22.1 to 26.7 mg (100 mg OC−1, and typically followed TOC concentrations in the estuarine and shelf sediments, suggesting that the relative abundance of total carbohydrate was fairly constant in TOC. Total neutral sugars as detected by the nine major monosaccharides (lyxose, rhamnose, ribose, arabinose, fucose, xylose, galactose, mannose, and glucose yielded between 4.0 and 18.6 mg (100 mg OC−1 in the same sediments, suggesting that a significant amount of carbohydrates were not neutral aldoses. The bulk organic matter properties, isotopic composition and C/N ratios, combined with molecular-level carbohydrate compositions were used to assess the sources and accumulation of terrestrial organic matter in the Pearl River Estuary and the adjacent northern South China Sea shelf. Results showed a mixture of terrestrial riverine organic carbon with in situ phytoplankton organic carbon in the areas studied. Using a two end-member mixing model based on δ13C values and C/N ratios, we estimated that the terrestrial organic carbon contribution to

  3. Carbon and Nitrogen Stable Isotope Composition of OM From Florida Bay, the Initial Results of a Paleoenvironmental Seagrass Reconstruction

    Science.gov (United States)

    Evans, S. L.; Anderson, W. T.; Fourqurean, J. W.; Jaffe, R.; Gaiser, E. E.; Collins, L. S.; Holmes, C. W.

    2002-12-01

    The shallow marine waters of Florida Bay provide an ideal environment for seagrasses, which are the most common benthic community in the region. However, these communities are susceptible to a variety of anthropogenic disturbances, particularly changes in water quality, and environmental conditions in Florida Bay have become a concern due to recent increases in salinity, the frequency of algal blooms, and seagrass die-off. These changes have been attributed to 20th century decreases in freshwater discharge from the Everglades to Florida Bay, deteriorated water quality, and changes in exchange between Florida Bay and the Atlantic Ocean. In order to better understand environmental change over long timescales, sediment cores were collected in the summer, 2002, from four locations in Florida Bay for multiple proxy analyses of seagrass abundance, which is an excellent indicator of water quality. Sediment depths ranged from 96 to 244 cm, potentially representing a 5000-year time series. Cores were sampled in 2-cm increments representing an average of 2-10 years for bulk isotopic analysis of sediment organic content. In 2 cores analyzed, δ15N values ranged between 3.2 and 7.6‰ , following an oscillating pattern over time. δ13C values ranged between -11.2 and -8.6‰ along a progressive enrichment trend that is inconsistent with the adjacent development of the metro Miami area and agricultural activities. These patterns show evidence of decoupling between carbon and nitrogen isotopic systems, although values throughout suggest that buried organic matter at these 2 sites is seagrass-derived. Further bulk isotopic analyses of remaining cores, together with organic biomarker analyses, diatom and foraminiferal community analyses, and development of an age model for the cores, will allow more definitive interpretation of the isotope patterns with implications to seagrass productivity levels, and thus, water quality, over time in Florida

  4. Stable carbon isotope labeling reveals different carry-over effects between functional types of tropical trees in an Ethiopian mountain forest.

    Science.gov (United States)

    Krepkowski, Julia; Gebrekirstos, Aster; Shibistova, Olga; Bräuning, Achim

    2013-07-01

    We present an intra-annual stable carbon isotope (δ(13)C) study based on a labeling experiment to illustrate differences in temporal patterns of recent carbon allocation to wood structures of two functional types of trees, Podocarpus falcatus (a late-successional evergreen conifer) and Croton macrostachyus (a deciduous broadleaved pioneer tree), in a tropical mountain forest in Ethiopia. Dendrometer data, wood anatomical thin sections, and intra-annual δ(13)C analyses were applied. Isotope data revealed a clear annual growth pattern in both studied species. For P. falcatus, it was possible to synchronize annual δ(13) C peaks, wood anatomical structures and monthly precipitation patterns. The labeling signature was evident for three consecutive years. For C. macrostachyus, isotope data illustrate a rapid decline of the labeling signal within half a year. Our δ(13)C labeling study indicates a distinct difference in carryover effects between trees of different functional types. A proportion of the labeled δ(13)C is stored in reserves of wood parenchyma for up to 3 yr in P. falcatus. By contrast, C. macrostachyus shows a high turnover of assimilates and a carbon carryover effect is only detectable in the subsequent year. PMID:23586968

  5. Stable carbon isotope labeling reveals different carry-over effects between functional types of tropical trees in an Ethiopian mountain forest.

    Science.gov (United States)

    Krepkowski, Julia; Gebrekirstos, Aster; Shibistova, Olga; Bräuning, Achim

    2013-07-01

    We present an intra-annual stable carbon isotope (δ(13)C) study based on a labeling experiment to illustrate differences in temporal patterns of recent carbon allocation to wood structures of two functional types of trees, Podocarpus falcatus (a late-successional evergreen conifer) and Croton macrostachyus (a deciduous broadleaved pioneer tree), in a tropical mountain forest in Ethiopia. Dendrometer data, wood anatomical thin sections, and intra-annual δ(13)C analyses were applied. Isotope data revealed a clear annual growth pattern in both studied species. For P. falcatus, it was possible to synchronize annual δ(13) C peaks, wood anatomical structures and monthly precipitation patterns. The labeling signature was evident for three consecutive years. For C. macrostachyus, isotope data illustrate a rapid decline of the labeling signal within half a year. Our δ(13)C labeling study indicates a distinct difference in carryover effects between trees of different functional types. A proportion of the labeled δ(13)C is stored in reserves of wood parenchyma for up to 3 yr in P. falcatus. By contrast, C. macrostachyus shows a high turnover of assimilates and a carbon carryover effect is only detectable in the subsequent year.

  6. Differential processing of anthropogenic carbon and nitrogen in benthic food webs of A Coruña (NW Spain) traced by stable isotopes

    OpenAIRE

    Bode, A.; Fernández, C.; Mompeán, C.; Parra, S.; Rozada, F.; Valencia-Vila, J. (Joaquín); Viana, I. G.

    2014-01-01

    proyectos ANILE (CTM2009- 08396 and CTM2010-08804-E) del Plan Nacional de I+D+i y RADIALES del Instituto Español de Oceanografía (IEO). C.M. e I.G.V. disfrutaron de contratos FPI del IEO y del Ministerio de Economía y Competividad respectivamente. In this study the effect of inputs of organic matter and anthropogenic nitrogen at small spatial scales were investigated in the benthos of the Ria of A Coruña (NW Spain) using stable carbon and nitrogen isotopes. This ria is characteri...

  7. Stable isotope views on ecosystem function: challenging or challenged?

    Science.gov (United States)

    Resco, Víctor; Querejeta, José I.; Ogle, Kiona; Voltas, Jordi; Sebastià, Maria-Teresa; Serrano-Ortiz, Penélope; Linares, Juan C.; Moreno-Gutiérrez, Cristina; Herrero, Asier; Carreira, José A.; Torres-Cañabate, Patricia; Valladares, Fernando

    2010-01-01

    Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Úbeda, 18–22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes. PMID:20015858

  8. Reconstructing Past Vegetation Types During the Late Holocene Using Stable Carbon Isotopes of Leporids from Archaeological Sites in the American Southwest

    Science.gov (United States)

    Mauldin, R. P.; Munoz, C.; Kemp, L.; Hard, R.

    2012-12-01

    Stable carbon isotopes (δ13C) from bone collagen in leporids provide high-resolution vegetation reconstruction. Leporids [e.g., cottontails (Sylvilagus sp.), jackrabbits (Lepus sp.)] die young (ca. 2 years) and use small home ranges (diet, and their bone collagen, provides a high-resolution view of the carbon isotopic values present in their local plant community. Here we provide an example of the use of leporid bone collagen for reconstruction of past vegetation types using data from several archaeological sites as well as modern collections. All samples are from a basin and range setting within the Chihuahuan Desert in far west Texas and southern New Mexico, USA. The sites span a period back to roughly 1350 BP. Isotopic patterns in leporid collagen show clear evidence of change in vegetation from around 775 BP to the modern period, with a dramatic shift of 4.2‰ in median δ13C values over this period in jackrabbit collagen and a 7.3‰ decrease in median carbon isotopic values in cottontail rabbits. These data suggest a significant increase in C3 plants in leporid diet, and by extension a relative increase in these plant types in the local environment sampled by leporids. This shift is consistent with historic accounts of more C3 mesquite, possibly because of historic land use and ranching practices in the 1800s. However, while this shift may have been accelerated by historic land use changes, our data suggest that the vegetation shift began several hundred years earlier during the prehistoric period. The prehistoric collagen isotopic record also shows increased sample variability through time in both species, suggesting that year-to-year variability in vegetation may have increased late in that sequence. Our results, then, clearly show the potential of leporids for high resolution tracking of vegetation shifts. As leporids are common in paleontological and archaeological sites throughout the temperate zones, their use as a vegetation and climate proxy has

  9. Carbon and oxygen stable isotope data as paleoenvironmental indicators for limestones from the Campos, Santos and Espirito Santo Basins, Brazil

    International Nuclear Information System (INIS)

    Carbon and oxygen isotope data of limestones from Campos, Santos and Espirito Santo basins provided additional information on the sedimentation environments of these carbonates. The predominance of δ 13C values between + 1,0 per mille and - 1,0 per mille samples from the Tertiary and the middle section of the Jiquia Stage (Lower Cretaceous) could indiccate, for both carbonate sequences, deposition in a normal marine environment. However, the absence of marine fossils in the Jiquia Stage but not in the Tertiary allows to suggest a normal marine environment for the latter and saline lakes for the former. More positive δ 13C values in the upper portion of the Jiquia Stage and in the Alagoas Stage suggest a restricted marine environment, with a tendency to hypersalinity. During the Albian the carbonate sedimentation could have occurred in a marine enrironment with an above normal salinity, as indicated by values of δ 13C between + 3,0 per mille and + 4,0 per mille. According to δ 18O data, the surface waters were warm, with a tendency of becoming gradually cooler towards the top of the Tertiary. (Author)

  10. New 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

    NARCIS (Netherlands)

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

    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 (c

  11. Stable Isotope Group 1981 progress report

    International Nuclear Information System (INIS)

    Geothermal studies were reported on the Tauhara, Wairakei, Orakeikorako and Mokai areas. We assisted the two N.Z. geothermal consultant companies with isotope analyses and the Geothermal Institute with lectures on stable isotope aspects of the diploma course. Sample collections were made at Ngawha and Wairakei. Oxygen isotope studies of central North Island volcanics have shown a negative correlation of delta 18O with SiO2 content of dacites and rhyolites; contamination of subcrustal rhyolite differentiates by greywacke appears the best explanation. A series of four papers on 'Environmental Isotopes in New Zealand Hydrology' was published during the year. Parts 1 and 2 described the principles and measurement techniques and Parts 3 and 4 described isotope studies of the Pupu Springs, Takaka and the groundwater resources of the Waimea Plains respectively. Carbon isotopes have proved useful in elucidating the food sources of freshwater insects in forest streams on the West Coast and brachiopods from Fiordland. Potassium-argon dating studies were completed on volcanics of the Auckland Islands, North Canterbury and East Otago, basement granites and meta-sediments of Marie Byrd Land, West Antarctica and slates in Western Tasmania. Rubidium-strontium computer programs were developed to control the solid-source mass spectrometer, chemical methods for preparation of strontium and rubidium samples were substantially improved and the first analyses of USGS rock standards were completed. Fission-track dating on minerals from granites from Buller and Westland have shown ages of 100-150Ma on the West Coast decreasing to about 5Ma at the Alpine Fault, reflecting recent uplift there

  12. 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.

  13. Application of ultrafiltration and stable isotopic amendments to field studies of mercury partitioning to filterable carbon in lake water and overland runoff

    Science.gov (United States)

    Babiarz, C.L.; Hurley, J.P.; Krabbenhoft, D.P.; Gilmour, C.; Branfireun, B.A.

    2003-01-01

    Results from pilot studies on colloidal phase transport of newly deposited mercury in lake water and overland runoff demonstrate that the combination of ultrafiltration, and stable isotope amendment techniques is a viable tool for the study of mercury partitioning to filterable carbon. Ultrafiltration mass balance calculations were generally excellent, averaging 97.3, 96.1 and 99.8% for dissolved organic carbon (DOC), total mercury (HgT), and methylmercury (MeHg), respectively. Sub nanogram per liter quantities of isotope were measurable, and the observed phase distribution from replicate ultrafiltration separations on lake water agreed within 20%. We believe the data presented here are the first published colloidal phase mercury data on lake water and overland runoff from uncontaminated sites. Initial results from pilot-scale lake amendment experiments indicate that the choice of matrix used to dissolve the isotope did not affect the initial phase distribution of the added mercury in the lake. In addition there was anecdotal evidence that native MeHg was either recently produced in the system, or at a minimum, that this 'old' MeHg partitions to the same subset of DOC that binds the amended mercury. Initial results from pilot-scale overland runoff experiments indicate that less than 20% of newly deposited mercury was transported in the filterable fraction (<0.7 ??m). There is some indication of colloidal phase enrichment of mercury in runoff compared to the phase distribution of organic carbon, but the mechanism of this enrichment is unclear. The phase distribution of newly deposited mercury can differ from that of organic carbon and native mercury, suggesting that the quality of the carbon (available ligands), not the quantity of carbon, regulates partitioning. Further characterization of DOC is needed to clarify the underlying mechanisms. ?? 2002 Elsevier Science B.V. All rights reserved.

  14. Substitution of stable isotopes in Chlorella

    Science.gov (United States)

    Flaumenhaft, E.; Katz, J. J.; Uphaus, R. A.

    1969-01-01

    Replacement of biologically important isotopes in the alga Chlorella by corresponding heavier stable isotopes produces increasingly greater deviations from the normal cell size and changes the quality and distribution of certain cellular components. The usefulness of isotopically altered organisms increases interest in the study of such permuted organisms.

  15. Development of a non-destructive micro-analytical method for stable carbon isotope analysis of transmission electron microscope (TEM) samples

    Science.gov (United States)

    Hode, Tomas; Kristiansson, Per; Elfman, Mikael; Hugo, Richard C.; Cady, Sherry L.

    2009-10-01

    The biogenicity of ancient morphological microfossil-like objects can be established by linking morphological (e.g. cell remnants and extracellular polymeric matrix) and chemical (e.g. isotopes, biomarkers and biominerals) evidence indicative of microorganisms or microbial activity. We have developed a non-destructive micro-analytical ion beam system capable of measuring with high spatial resolution the stable carbon isotope ratios of thin samples used for transmission electron microscopy. The technique is based on elastic scattering of alpha particles with an energy of 2.751 MeV. At this energy the 13C cross section is enhanced relative to the pure Rutherford cross section for 13C, whereas the 12C cross section is reduced relative to its pure Rutherford cross section. Here we report the initial results of this experimental approach used to characterize ultramicrotomed sections of sulfur-embedded graphite and microbial cells.

  16. Applications of stable isotopes in clinical pharmacology

    NARCIS (Netherlands)

    Schellekens, Reinout C A; Stellaard, Frans; Woerdenbag, Herman J; Frijlink, Henderik W; Kosterink, Jos G W

    2011-01-01

    This review aims to present an overview of the application of stable isotope technology in clinical pharmacology. Three main categories of stable isotope technology can be distinguished in clinical pharmacology. Firstly, it is applied in the assessment of drug pharmacology to determine the pharmacok

  17. Modelling stable water isotopes: Status and perspectives

    Directory of Open Access Journals (Sweden)

    Werner M.

    2010-12-01

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

  18. Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions

    Science.gov (United States)

    He, B.; Dai, M.; Huang, W.; Liu, Q.; Chen, H.; Xu, L.

    2010-10-01

    Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized using a variety of techniques, including elemental (C and N) ratio, bulk stable organic carbon isotopic composition (δ13C), and carbohydrate composition analyses. Total organic carbon (TOC) content was 1.21±0.45% in the upper reach, down to 1.00±0.22% in Lingdingyang Bay and to 0.80±0.10% on the inner shelf and 0.58±0.06% on the outer shelf. δ13C values ranged from -25.1‰ to -21.3‰ in Lingdingyang Bay and the South China Sea shelf, with a trend of enrichment seawards. The spatial trend in C/N ratios mirrored that of δ13C, with a substantial decrease in C/N ratio offshore. Total carbohydrate yields ranged from 22.1 to 26.7 mg (100 mg OC)-1, and typically followed TOC concentrations in the estuarine and shelf sediments. Total neutral sugars, as detected by the nine major monosaccharides (lyxose, rhamnose, ribose, arabinose, fucose, xylose, galactose, mannose, and glucose), were between 4.0 and 18.6 mg (100 mg OC)-1 in the same sediments, suggesting that significant amounts of carbohydrates were not neutral aldoses. Using a two end-member mixing model based on δ13C values and C/N ratios, we estimated that the terrestrial organic carbon contribution to the surface sediment TOC was ca. 78±11% for Lingdingyang Bay, 34±4% for the inner shelf, and 5.5±1% for the outer shelf. The molecular composition of the carbohydrate in the surface sediments also suggested that the inner estuary was rich in terrestrially derived carbohydrates but that their contribution decreased offshore. A relatively high abundance of deoxyhexoses in the estuary and shelf indicated a considerable bacterial source of these carbohydrates, implying that sediment organic matter had undergone extensive degradation and/or transformation during transport. Sediment budget based on calculated regional accumulation rates

  19. Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions

    Directory of Open Access Journals (Sweden)

    B. He

    2010-10-01

    Full Text Available Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized using a variety of techniques, including elemental (C and N ratio, bulk stable organic carbon isotopic composition (δ13C, and carbohydrate composition analyses. Total organic carbon (TOC content was 1.21±0.45% in the upper reach, down to 1.00±0.22% in Lingdingyang Bay and to 0.80±0.10% on the inner shelf and 0.58±0.06% on the outer shelf. δ13C values ranged from −25.1‰ to −21.3‰ in Lingdingyang Bay and the South China Sea shelf, with a trend of enrichment seawards. The spatial trend in C/N ratios mirrored that of δ13C, with a substantial decrease in C/N ratio offshore. Total carbohydrate yields ranged from 22.1 to 26.7 mg (100 mg OC−1, and typically followed TOC concentrations in the estuarine and shelf sediments. Total neutral sugars, as detected by the nine major monosaccharides (lyxose, rhamnose, ribose, arabinose, fucose, xylose, galactose, mannose, and glucose, were between 4.0 and 18.6 mg (100 mg OC−1 in the same sediments, suggesting that significant amounts of carbohydrates were not neutral aldoses. Using a two end-member mixing model based on δ13C values and C/N ratios, we estimated that the terrestrial organic carbon contribution to the surface sediment TOC was ca. 78±11% for Lingdingyang Bay, 34±4% for the inner shelf, and 5.5±1% for the outer shelf. The molecular composition of the carbohydrate in the surface sediments also suggested that the inner estuary was rich in terrestrially derived carbohydrates but that their contribution decreased offshore. A relatively high abundance of deoxyhexoses in the estuary and shelf indicated a considerable bacterial source of these carbohydrates, implying that sediment organic matter had undergone extensive degradation and

  20. Rare stable isotopes in meteorites

    International Nuclear Information System (INIS)

    Secondary Ion Mass Spectrometry (SIMS) using accelerators has been applied with success to cosmic ray exposure ages and terrestrial residence times of meteorites by measuring cosmogenic nuclides of Be, Cl, and I. It is proposed to complement this work with experiments on rare stable isotopes, in the hope of setting constraints on the processes of solar nebula/meteoritic formation. The relevant species can be classified as: a) daughter products of extinct nuclides (halflife less than or equal to 2 x 108 y) -chronology of the early solar system; b) products of high temperature astrophysical processes - different components incorporated into the solar nebula; and c) products of relatively low temperature processes, stellar winds and cosmic ray reactions - early solar system radiation history. The use of micron-scale primary ion beams will allow detailed sampling of phases within meteorites. Strategies of charge-state selection, molecular disintegration and detection should bring a new set of targets within analytical range. The developing accelerator field is compared to existing (keV energy) ion microprobes

  1. Food web of a confined and anthropogenically affected coastal basin (the Mar Piccolo of Taranto) revealed by carbon and nitrogen stable isotopes analyses.

    Science.gov (United States)

    Bongiorni, Lucia; Fiorentino, Federica; Auriemma, Rocco; Aubry, Fabrizio Bernardi; Camatti, Elisa; Camin, Federica; Nasi, Federica; Pansera, Marco; Ziller, Luca; Grall, Jacques

    2016-07-01

    Carbon and nitrogen stable isotope analysis was used to examine the food web of the Mar Piccolo of Taranto, a coastal basin experiencing several anthropogenic impacts. Main food sources (algal detritus, seaweeds, particulate organic matter (POM) and sediment organic matter (SOM)) and benthic and pelagic consumers were collected during two contrasting seasons (June and April), at four sites distributed over two inlets, and characterized by different level of confinements, anthropogenic inputs and the presence of mussels farming. δ(13)C values of organic sources revealed an important contribution of POM to both planktonic and benthic pathways, as well as the influence of terrigenous inputs within both inlets, probably due to high seasonal land runoff. Although δ(13)C of both sources and consumers varied little between sampling sites and dates, δ(15)N spatial variability was higher and clearly reflected the organic enrichment in the second inlet as well as the uptake of anthropogenically derived material by benthic consumers. On the other hand, within the first inlet, the isotopic composition of consumers did not change in response to chemical contamination. However, the impact of polluted sediments near the Navy Arsenal in the first inlet was detectable at the level of the macrobenthic trophic structure, showing high dominance of motile, upper level consumers capable to face transient conditions and the reduction of the more resident deposit feeders. We therefore underline the great potential of matching stable isotope analysis with quantitative studies of community structure to assess the effects of multiple anthropogenic stressors.

  2. Reconstructing Changes in Deep Ocean Temperature and Global Carbon Cycle during the Early Eocene Warming Trend: High-Resolution Benthic Stable Isotope Records from the SE Atlantic.

    Science.gov (United States)

    Lauretano, V.; Zachos, J. C.; Lourens, L. J.

    2014-12-01

    From the late Paleocene to the early Eocene, Earth's surface temperatures generally rose, resulting in an increase of at least 5°C in the deep ocean and culminating in the Early Eocene Climatic Optimum (EECO). This long-term warming was punctuated by a series of short-lived global warming events known as "hyperthermals", of which the Paleocene-Eocene Thermal Maximum (PETM) represents the most extreme example. At least two other short-term episodes have been identified as hyperthermals: the ETM2 (or Elmo event) at about 53.7 Myr and the ETM3 (or X-event) at about 52.5 Myr. These transient events are marked by prominent carbon isotope excursions (CIEs), recorded in marine and continental sedimentary sequences and driven by fast and massive injections of 13C-depleted carbon into the ocean-atmosphere system. Recently, evidence has indicated the presence of a regular series of hyperthermal events following the peak in temperatures of the EECO. However, continuous records are needed to investigate short- and long- term changes in the climate system throughout the Early Eocene warming trend. Here, we present new high-resolution benthic stable isotope records of the Early Eocene from ODP Site 1263, (Walvis Ridge, SE Atlantic). The carbon and oxygen records document changes in deep-sea temperature and global carbon cycle encompassing the Early Eocene hyperthermal events and the EECO interval. The transition phase to the post-EECO events is distinct by the decoupling of carbon and oxygen isotopes on the long-term scale. Spectral and wavelet analyses suggest the influence of orbital forcing, specifically long and short eccentricity cycles.

  3. Environment and ecology of East Asian dinosaurs during the Early Cretaceous inferred from stable oxygen and carbon isotopes in apatite

    Science.gov (United States)

    Amiot, Romain; Wang, Xu; Zhou, Zhonghe; Wang, Xiaolin; Lécuyer, Christophe; Buffetaut, Eric; Fluteau, Frédéric; Ding, Zhongli; Kusuhashi, Nao; Mo, Jinyou; Philippe, Marc; Suteethorn, Varavudh; Wang, Yuanqing; Xu, Xing

    2015-02-01

    During the cold Late Barremian-Early Albian interval, terrestrial environments in East Asia were populated by rich and diverse vertebrate faunas characterized by a strong provincialism. The latitudinal gradient of temperature and the existence of geographic barriers likely accounted for some aspects of this heterogeneous distribution of faunas. Other factors, however, such as local environmental conditions and interactions within vertebrate communities, which could have influenced their distribution, have not yet been fully identified and understood. Therefore, new and published oxygen and carbon isotope compositions of apatite from Chinese and Thai reptiles (dinosaurs, crocodilians and turtles) have been analyzed and interpreted in terms of ecology, local air temperature and precipitation amounts. Differences in carbon and oxygen isotope compositions between various groups of sympatric plant-eating dinosaurs (sauropods, ornithopods and ceratopsians) indicate food resources partitioning among them most likely to avoid competition. Mid-latitude environments, where the Jehol Biota flourished, were submitted to cool temperate climatic conditions with Mean Air Temperature (MAT) of 10 ± 4 °C and Mean Annual Precipitations (MAP) of about 600 mm/yr compatible with the existence of forest environments. By contrast, sub-tropical regions, characterized by MAT of about 20-25 °C were either submitted to high amounts of seasonal precipitations (of about 1200 mm/yr in Thailand) or to significant aridity (MAP of about 400 mm/yr in South China). This difference in precipitation regime between Thailand and South China may be attributed to the occurrence of the Coastal Cordillera extending along the East margin of the South China block. These mountain ranges likely prevented humid air masses from the Pacific to penetrate some parts of South China, thus generating a "rain shadow effect". Mosaic environments characterizing East Asia during the Late Early Cretaceous may have acted

  4. A new CF-IRMS system for the quantification of the stable isotopes of carbon monoxide from ice cores and small air samples

    Directory of Open Access Journals (Sweden)

    Z. Wang

    2009-10-01

    Full Text Available A new simultaneous analysis technique for stable isotope ratios (δ13C and δ18O of atmospheric carbon monoxide (CO from ice core samples and small air samples is presented, based on an on-line cryogenic vacuum extraction followed by continuous-flow isotope ratio mass spectrometry (CF-IRMS. The CO extraction system includes two multi-loop cryogenic cleanup traps, a chemical oxidant for oxidation to CO2, a cryogenic collection trap, a cryofocusing unit, purification by gas chromatography, and subsequent injection into a Finnigan Delta Plus IRMS. Analytical precision of 0.2‰(±1σ for δ13C and 0.6‰(±1σ for δ18O can be obtained for 100 mL (STP air sample with CO mixing ratio ranging from 60 to 140 ppbv (~268–625 pmol CO. Six South Pole ice core samples with depth ranging from 133 to 177 m are also processed for CO isotope analysis based on a wet extraction line attached to the above cryogenic vacuum system. This is the first report on measuring isotope ratios of CO in ice core samples.

  5. Assessment of marine-derived nutrients in the Copper River Delta, Alaska, using natural abundance of the stable isotopes of nitrogen, sulfur, and carbon

    Science.gov (United States)

    Kline, Thomas C.; Woody, Carol Ann; Bishop, Mary Anne; Powers, Sean P.; Knudsen, E. Eric

    2007-01-01

    We performed nitrogen, sulfur, and carbon stable isotope analysis (SIA) on maturing and juvenile anadromous sockeye and coho salmon, and periphyton in two Copper River delta watersheds of Alaska to trace salmonderived nutrients during 2003–2004. Maturing salmon were isotopically enriched relative to alternate freshwater N, S, and C sources as expected, with differences consistent with species trophic level differences, and minor system, sex, and year-to-year differences, enabling use of SIA to trace these salmon-derived nutrients. Periphyton naturally colonized, incubated, and collected using Wildco Periphtyon Samplers in and near spawning sites was 34S- and 15N-enriched, as expected, and at all freshwater sites was 13C-depleted. At nonspawning and coho-only sites, periphyton 34S and 15N was generally low. However, 34S was low enough at some sites to be suggestive of sulfate reduction, complicating the use of S isotopes. Juvenile salmon SIA ranged in values consistent with using production derived from re-mineralization as well as direct utilization, but only by a minority fraction of coho salmon. Dependency on salmon-derived nutrients ranged from relatively high to relatively low, suggesting a space-limited system. No one particular isotope was found to be superior for determining the relative importance of salmon-derived nutrients.

  6. 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.

  7. 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

  8. Stable carbon isotopic compositions of low-molecular-weight dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and fatty acids: Implications for atmospheric processing of organic aerosols

    Science.gov (United States)

    Zhang, Yan-Lin; Kawamura, Kimitaka; Cao, Fang; Lee, Meehye

    2016-04-01

    Stable carbon isotopic compositions (δ13C) were measured for 23 individual organic species including 9 dicarboxylic acids, 7 oxocarboxylic acids, 1 tricarboxylic acid, 2 α-dicarbonyls, and 4 fatty acids in the aerosols from Gosan background site in East Asia. δ13C values of particle phase glyoxal and methylglyoxal are significantly larger than those previously reported for isoprene and other precursors. The values are consistently less negative in oxalic acid (C2, average -14.1‰), glyoxylic acid (-13.8‰), pyruvic acid (-19.4‰), glyoxal (-13.5‰), and methylglyoxal (-18.6‰) compared to other organic species (e.g., palmitic acid, -26.3‰), which can be explained by the kinetic isotope effects during atmospheric oxidation of pre-aged precursors (e.g., isoprene) and the subsequent gas-particle partitioning after the evaporation of clouds or wet aerosols. The δ13C values of C2 is positively correlated with C2 to organic carbon ratio, indicating that photochemical production of C2 is more pronounced than its degradation during long-range atmospheric transport. The isotopic results also suggest that aqueous phase oxidation of glyoxal and methylglyoxal is a major formation process of oxalic acid via the intermediates such as glyoxylic acid and pyruvic acid. This study provides evidence that organic aerosols are intensively photochemically aged in the western North Pacific rim.

  9. 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

  10. Stable carbon isotopes of HCO3- in oil-field waters-implications for the origin of CO2

    Science.gov (United States)

    Carothers, W.W.; Kharaka, Y.K.

    1980-01-01

    The ??13C values of dissolved HCO3- in 75 water samples from 15 oil and gas fields (San Joaquin Valley, Calif., and the Houston-Galveston and Corpus Christi areas of Texas) were determined to study the sources of CO2 of the dissolved species and carbonate cements that modify the porosity and permeability of many petroleum reservoir rocks. The reservoir rocks are sandstones which range in age from Eocene through Miocene. The ??13C values of total HCO3- indicate that the carbon in the dissolved carbonate species and carbonate cements is mainly of organic origin. The range of ??13C values for the HCO3- of these waters is -20-28 per mil relative to PDB. This wide range of ??13C values is explained by three mechanisms. Microbiological degradation of organic matter appears to be the dominant process controlling the extremely low and high ??13C values of HCO3- in the shallow production zones where the subsurface temperatures are less than 80??C. The extremely low ??13C values (bacteria (SO42- + CH3COO- ??? 2HCO3- + HS-). The high ??13C values probably result from the degradation of these anions by methanogenic bacteria (CH3COO- + H2O ai HCO3- + CH4). Thermal decarboxylation of short-chain aliphatic acid anions (principally acetate) to produce CO2 and CH4 is probably the major source of CO2 for production zones with subsurface temperatures greater than 80??C. The ??13C values of HCO3- for waters from zones with temperatures greater than 100??C result from isotopic equilibration between CO2 and CH4. At these high temperatures, ??13C values of HCO3- decrease with increasing temperatures and decreasing concentrations of these acid anions. ?? 1980.

  11. Carbon and nitrogen stable isotopes and metal concentration in food webs from a mining-impacted coastal lagoon.

    Science.gov (United States)

    Marín-Guirao, Lázaro; Lloret, Javier; Marin, Arnaldo

    2008-04-01

    Two food webs from the Mar Menor coastal lagoon, differing in the distance from the desert-stream through which mining wastes were discharged, were examined by reference to essential (Zn and Cu) and non-essential (Pb and Cd) metal concentrations and stable isotopes content (C and N). The partial extraction technique applied, which reflects the availability of metals to organisms after sediment ingestion, showed higher bioavailable metal concentrations in sediments from the station influenced by the mining discharges, in agreement with the higher metal concentrations observed in organisms, which in many cases exceeded the regulatory limits established in Spanish legislation concerning seafood. Spatial differences in essential metal concentrations in the fauna suggest that several organisms are exposed to metal levels above their regulation capacity. Differences in isotopic composition were found between both food webs, the wadi-influenced station showing higher delta(15)N values and lower delta(13)C levels, due to the discharge of urban waste waters and by the entrance of freshwater and allochthonous marsh plants. The linear-regressions between trophic levels (as indicated by delta(15)N) and the metal content indicated that biomagnification does not occur. In the case of invertebrates, since the "handle strategy" of the species and the physiological requirements of the organisms, among other factors, determine the final concentration of a specific element, no clear relationships between trophic level and the metal content are to be expected. For their part, fish communities did not show clear patterns in the case of any of the analyzed metals, probably because most fish species have similar metal requirements, and because biological factors also intervened. Finally, since the study deals with metals, assumptions concerning trophic transfer factors calculation may not be suitable since the metal burden originates not only from the prey but also from adsorption over

  12. Stable carbon isotope analysis ({delta}{sup 13}C values) of polybrominated diphenyl ethers and their UV-transformation products

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfelder, Natalie; Bendig, Paul [University of Hohenheim, Institute of Food Chemistry (170b), Garbenstr. 28, D-70599 Stuttgart (Germany); Vetter, Walter, E-mail: walter.vetter@uni-hohenheim.de [University of Hohenheim, Institute of Food Chemistry (170b), Garbenstr. 28, D-70599 Stuttgart (Germany)

    2011-10-15

    Polybrominated diphenyl ethers (PBDEs) are frequently detected in food and environmental samples. We used compound specific isotope analysis to determine the {delta}{sup 13}C values of individual PBDEs in two technical mixtures. Within the same technical product (DE-71 or DE-79), BDE congeners were the more depleted in {sup 13}C the higher brominated they were. In contrast, the products of light-induced hydrodebromination of BDE 47 and technical DE-79 were more enriched in {sup 13}C because of more stable bonds between {sup 13}C and bromine. As a result, the {delta}{sup 13}C values of the irradiated solution progressed diametrically compared to those of the technical synthesis. The ratio of the {delta}{sup 13}C values of BDE 47 to BDE 99 and of BDE 99 to BDE 153 are thus suggested as indicators to distinguish native technical products from transformation products. Ratios <1 are typical for native congeners (e.g. in DE-71) while the reversed ratio (>1) is typical of transformation products. - Highlights: > {delta}{sup 13}C values of PBDEs were determined by means of compound specific isotope analysis. > PBDEs in technical mixtures were the more depleted in {sup 13}C the higher they were brominated. > Solutions of individual PBDEs and technical PBDE mixtures were irradiated by UV light. > {delta}{sup 13}C values of irradiated PBDEs and technical PBDEs progressed diametrically. > Ratios of the {delta}{sup 13}C values were used to distinguish native from transformed PBDEs. - Diametrically progressing {delta}{sup 13}C values in technical mixtures and UV-transformation products of DE-79 may be useful for source appointment of PBDEs in environmental samples

  13. Carbon and nitrogen stable isotopes and metal concentration in food webs from a mining-impacted coastal lagoon

    Energy Technology Data Exchange (ETDEWEB)

    Marin-Guirao, Lazaro [Departamento de Ecologia e Hidrologia, Facultad de Biologia, Universidad de Murcia, 30100-Murcia (Spain)], E-mail: lamarin@um.es; Lloret, Javier; Marin, Arnaldo [Departamento de Ecologia e Hidrologia, Facultad de Biologia, Universidad de Murcia, 30100-Murcia (Spain)

    2008-04-01

    Two food webs from the Mar Menor coastal lagoon, differing in the distance from the desert-stream through which mining wastes were discharged, were examined by reference to essential (Zn and Cu) and non-essential (Pb and Cd) metal concentrations and stable isotopes content (C and N). The partial extraction technique applied, which reflects the availability of metals to organisms after sediment ingestion, showed higher bioavailable metal concentrations in sediments from the station influenced by the mining discharges, in agreement with the higher metal concentrations observed in organisms, which in many cases exceeded the regulatory limits established in Spanish legislation concerning seafood. Spatial differences in essential metal concentrations in the fauna suggest that several organisms are exposed to metal levels above their regulation capacity. Differences in isotopic composition were found between both food webs, the wadi-influenced station showing higher {delta}{sup 15}N values and lower {delta}{sup 13}C levels, due to the discharge of urban waste waters and by the entrance of freshwater and allochthonous marsh plants. The linear-regressions between trophic levels (as indicated by {delta}{sup 15}N) and the metal content indicated that biomagnification does not occur. In the case of invertebrates, since the 'handle strategy' of the species and the physiological requirements of the organisms, among other factors, determine the final concentration of a specific element, no clear relationships between trophic level and the metal content are to be expected. For their part, fish communities did not show clear patterns in the case of any of the analyzed metals, probably because most fish species have similar metal requirements, and because biological factors also intervened. Finally, since the study deals with metals, assumptions concerning trophic transfer factors calculation may not be suitable since the metal burden originates not only from the prey but

  14. Composition of Hydrothermal Vent Microbial Communities as Revealed by Analyses of Signature Lipids, Stable Carbon Isotopes and Aquificales Cultures

    Science.gov (United States)

    Jahnke, Linda L.; Eder, Wolfgang; Huber, Robert; Hinrichs, Kai-Uwe; Hayes, John M.; Cady, Sherry L.; DesMarais, David J.; Hope, Janet M.; Summons, Roger E.

    2001-01-01

    Extremely thermophilic microbial communities associated with the siliceous vent walls and outflow channel of Octopus Spring, Yellowstone National Park, have been examined for lipid biomarker and carbon isotopic signatures. These data were compared with that obtained from representatives of three Aquificales genera. Thermocrinis ruber, Thermocrinis sp. HI, Hydrogenobacter thermophilus, Aquifex pyrophilus and Aquifex aeolicus all contained phospholipids composed not only of the usual ester-linked fatty acids, but also ether-linked alkyl moieties. The fatty acids of all cultured organisms were dominated by very distinct pattern of n-C-20:1 and cy-C-21 compounds. The alkyl glycerol ethers were present primarily as C-18:0 monoethers with the exception of the Aquifex spp. in which dialkyl glycerol ethers with a boarder carbon-number distribution were also present. These Aquificales biomarker lipids were the major constituents in the lipid extracts of the Octopus Spring microbial samples. Two natural samples, a microbial biofilm growing in association with deposition of amorphous silica on the vent walls at 92 C, and the well-known "pink-streamer community" (PSC), siliceous filaments of a microbial consortia growing in the outflow channel at 87 C were analyzed. Both the biofilm and PSC samples contained mono- and dialkyl glycerol ethers with a prevalence of C-18 and C-20 alkyls. Phospholipid fatty acids were comprised of both the characteristic. Additional information is contained in the original extended abstract.

  15. Soil organic carbon dynamics under long-term fertilization in a black soil of China: Evidence from stable C isotopes.

    Science.gov (United States)

    Dou, Xiaolin; He, Ping; Zhu, Ping; Zhou, Wei

    2016-01-01

    Effects of different fertilizers on organic carbon (C) storage and turnover of soil fractions remains unclear. We combined soil fractionation with isotope analyses to examine soil organic carbon (SOC) dynamics after 25 years of fertilization. Five types of soil samples including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, N; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into four aggregate sizes (>2000 μm, 2000-250 μm, 250-53 μm, and organic matter (iPOM), and mineral-associated organic matter (mSOM). Physical fractionation showed the iPOM fraction of aggregates dominated C storage, averaging 76.87% of SOC storage. Overall, application of N and NPK fertilizers cannot significantly increase the SOC storage but enhanced C in mSOM of aggregates, whereas MNPK fertilizer resulted in the greatest amount of SOC storage (about 5221.5 g C m(2)) because of the enhanced SOC in LF, iPOM and mSOM of each aggregate. The SNPK fertilizer increased SOC storage in >250 μm aggregates but reduced SOC storage in <250 μm aggregates due to SOC changes in LF and iPOM. PMID:26898121

  16. Soil organic carbon dynamics under long-term fertilization in a black soil of China: Evidence from stable C isotopes

    Science.gov (United States)

    Dou, Xiaolin; He, Ping; Zhu, Ping; Zhou, Wei

    2016-02-01

    Effects of different fertilizers on organic carbon (C) storage and turnover of soil fractions remains unclear. We combined soil fractionation with isotope analyses to examine soil organic carbon (SOC) dynamics after 25 years of fertilization. Five types of soil samples including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, N; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into four aggregate sizes (>2000 μm, 2000-250 μm, 250-53 μm, and NPK fertilizers cannot significantly increase the SOC storage but enhanced C in mSOM of aggregates, whereas MNPK fertilizer resulted in the greatest amount of SOC storage (about 5221.5 g C m2) because of the enhanced SOC in LF, iPOM and mSOM of each aggregate. The SNPK fertilizer increased SOC storage in >250 μm aggregates but reduced SOC storage in <250 μm aggregates due to SOC changes in LF and iPOM.

  17. Soil organic carbon dynamics under long-term fertilization in a black soil of China: Evidence from stable C isotopes.

    Science.gov (United States)

    Dou, Xiaolin; He, Ping; Zhu, Ping; Zhou, Wei

    2016-01-01

    Effects of different fertilizers on organic carbon (C) storage and turnover of soil fractions remains unclear. We combined soil fractionation with isotope analyses to examine soil organic carbon (SOC) dynamics after 25 years of fertilization. Five types of soil samples including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, N; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into four aggregate sizes (>2000 μm, 2000-250 μm, 250-53 μm, and organic matter (iPOM), and mineral-associated organic matter (mSOM). Physical fractionation showed the iPOM fraction of aggregates dominated C storage, averaging 76.87% of SOC storage. Overall, application of N and NPK fertilizers cannot significantly increase the SOC storage but enhanced C in mSOM of aggregates, whereas MNPK fertilizer resulted in the greatest amount of SOC storage (about 5221.5 g C m(2)) because of the enhanced SOC in LF, iPOM and mSOM of each aggregate. The SNPK fertilizer increased SOC storage in >250 μm aggregates but reduced SOC storage in <250 μm aggregates due to SOC changes in LF and iPOM.

  18. Stable light isotope biogeochemistry of hydrothermal systems

    Science.gov (United States)

    Des Marais, D. J.

    1996-01-01

    The stable isotopic composition of the elements O, H, S and C in minerals and other chemical species can indicate the existence, extent, conditions and the processes (including biological activity) of hydrothermal systems. Hydrothermal alteration of the 18O/16O and D/H values of minerals can be used to detect fossil systems and delineate their areal extent. Water-rock interactions create isotopic signatures which indicate fluid composition, temperature, water-rock ratios, etc. The 18O/16O values of silica and carbonate deposits tend to increase with declining temperature and thus help to map thermal gradients. Measurements of D/H values can help to decipher the origin(s) of hydrothermal fluids. The 34S/32S and 13C/12C values of fluids and minerals reflect the origin of the S and C as well as oxygen fugacities and key redox processes. For example, a wide range of 34S/32S values which are consistent with equilibration below 100 degrees C between sulfide and sulfate can be attributed to sulfur metabolizing bacteria. Depending on its magnitude, the difference in the 13C/12C value of CO2 and carbonates versus organic carbon might be attributed either to equilibrium at hydrothermal temperatures or, if the difference exceeds 1% (10/1000), to organic biosynthesis. Along the thermal gradients of thermal spring outflows, the 13C/12C value of carbonates and 13C-depleted microbial organic carbon increases, principally due to the outgassing of relatively 13C-depleted CO2.

  19. δ18O water isotope in the iLOVECLIM model (version 1.0 – Part 3: A paleoperspective based on present-day data-model comparison for oxygen stable isotopes in carbonates

    Directory of Open Access Journals (Sweden)

    T. Caley

    2013-03-01

    Full Text Available Oxygen stable isotopes (18O are among the most usual tools in paleoclimatology/paleoceanography. Simulation of oxygen stable isotopes allows testing how the past variability of these isotopes in water can be interpreted. By modelling the proxy directly in the model, the results can also be directly compared with the data. Water isotopes have been implemented in the global three-dimensional model of intermediate complexity iLOVECLIM allowing fully coupled atmosphere-ocean simulations. In this study, we present the validation of the model results for present day climate against global database for oxygen stable isotopes in carbonates. The limitation of the model together with the processes operating in the natural environment reveal the complexity of use the continental calcite 18O signal of speleothems for a data-model comparison exercise. On the contrary, the reconstructed surface ocean calcite δ18O signal in iLOVECLIM does show a very good agreement with late Holocene database (foraminifers at the global and regional scales. Our results indicate that temperature and the isotopic composition of the seawater are the main control on the fossil δ18O signal recorded in foraminifer shells and that depth habitat and seasonality play a role but have secondary importance. We argue that a data-model comparison for surface ocean calcite δ18O in past climate, such as the last glacial maximum (≈21 000 yr, could constitute an interesting tool for mapping the potential shifts of the frontal systems and circulation changes throughout time. Similarly, the potential changes in intermediate oceanic circulation systems in the past could be documented by a data (benthic foraminifers-model comparison exercise whereas future investigations are necessary in order to quantitatively compare the results with data for the deep ocean.

  20. δ18O water isotope in the iLOVECLIM model (version 1.0 – Part 3: A palaeo-perspective based on present-day data–model comparison for oxygen stable isotopes in carbonates

    Directory of Open Access Journals (Sweden)

    T. Caley

    2013-09-01

    Full Text Available Oxygen stable isotopes (δ18O are among the most useful tools in palaeoclimatology/palaeoceanography. Simulation of oxygen stable isotopes allows testing how the past variability of these isotopes in water can be interpreted. By modelling the proxy directly in the model, the results can also be directly compared with the data. Water isotopes have been implemented in the global three-dimensional model of intermediate complexity iLOVECLIM, allowing fully coupled atmosphere–ocean simulations. In this study, we present the validation of the model results for present-day climate against the global database for oxygen stable isotopes in carbonates. The limitation of the model together with the processes operating in the natural environment reveal the complexity of use the continental calcite-δ18O signal of speleothems for a global quantitative data–model comparison exercise. On the contrary, the reconstructed surface ocean calcite-δ18O signal in iLOVECLIM does show a very good agreement with the late Holocene database (foraminifers at the global and regional scales. Our results indicate that temperature and the isotopic composition of the seawater are the main control on the fossil-δ18O signal recorded in foraminifer shells when all species are grouped together. Depth habitat, seasonality and other ecological effects play a more significant role when individual species are considered. We argue that a data–model comparison for surface ocean calcite δ18O in past climates, such as the Last Glacial Maximum (≈ 21 000 yr, could constitute an interesting tool for mapping the potential shifts of the frontal systems and circulation changes throughout time. Similarly, the potential changes in intermediate oceanic circulation systems in the past could be documented by a data (benthic foraminifers-model comparison exercise whereas future investigations are necessary in order to quantitatively compare the results with data for the deep ocean.

  1. Climatic changes documented by stable isotopes of sedimentary carbonate in Lake Sugan, northeastern Tibetan Plateau of China, since 2 kaBP

    Institute of Scientific and Technical Information of China (English)

    QIANG Mingrui; CHEN Fahu; ZHANG Jiawu; GAO Shangyu; ZHOU Aifeng

    2005-01-01

    Lake Sugan at the northern edge of the Qaidam Basin was selected as the research object. The temporal sequence of sedimentary cores retrieved from Lake Sugan since 2 kaBP was reconstructed using the 210Pb, AMS 14C and conventional 14C dating methods. Carbon and oxygen isotopes of carbonate in the fine-grained lake sediments were analysed. Combined with the changes of δ18O values of surface water and air temperature observation data in the study area, it might be thought that theδ18O value of the carbonate indicates effective moisture, and the changes in δ13C values are related to annual freeze-up duration of the lake and indirectly indicate air temperature changes in winter half year. From the above, the sequence of climatic changes in the region since 2 kaBP was established. The climatic changes experienced five stages: Warm-dry climate during 0-190 AD; cold-dry climate during 190-580 AD; warm-dry climate during 580-1200 AD (MWP); cold-wet climate during 1200-1880 AD (LIA); cold-dry climate during 1880-1950 AD; and climate warming since 1950s. The air temperature changes in winter half year reflected by carbon isotope since 2 kaBP are in good agreement with the historical literature records and other geologic records, which shows that the climate changes recorded by the stable isotopes from Lake Sugan since 2 kaBP are of universal significance.

  2. Evaluation of the age related systematic patterns of stable oxygen and carbon isotope values of Swiss stone pine (Pinus cembra L.) Eastern Carpathians, Romania

    Science.gov (United States)

    Nagavciuc, Viorica; Popa, Ionel; Persoiu, Aurel; Kern, Zoltán

    2016-04-01

    Tree-ring derived stable isotope time series are becoming increasingly important parameters in investigation of past environmental changes. However, potential age related trend-bias on these parameters, and the proper handling of it, is still not well understood. We here present measurements on a new multicentennial data set of annually resolved stable oxygen (δ18O) and carbon (δ13C) isotope compositions from 3 living and 4 subfossil Stone pine (Pinus cembra) samples collected at a timberline habitat in the Eastern Carpathians (Romania) to evaluate any potential systematic ontogenetic pattern on their δ18O and δ13C data. Oldest analyzed ring represented 129th, 135th and 142th cambial year in the living and 115th, 130th, 165th and 250th cambial year in the subfossil samples. The fact that Stone pine samples are backbone of the longest dendrochronological series both in the Alps and the Carpathians arouses special interest concerning their potential in stable isotope dendroclimatological research. Whole-ring samples were prepared to alpha-cellulose by the modified Jayme-Wise method. Cellulose samples were analyzed by a high-temperature pyrolysis system (Thermo Quest TC-EA) coupled to an isotope ratio mass spectrometer (Thermo Finningan Delta V). A ring by ring (i.e., non-pooled) approach was followed since age-related trends are by definition intrinsic to individual tree-ring series so pooling of rings may distort the detection of the trends. Raw measured δ13C values have been corrected for changes in the atmospheric CO2 regarding both its stable isotope signature and mixing ratio. Neither isotopic parameter showed any age related variance bias suggesting a homoscedastic character. Alignment of the δ13C data by cambial age revealed a relatively short period (~40 years) of systematic behaviour manifested in a ~1‰ enrichment in 13C over a moderate but persistent positive trend (~0.33‰ per 100years, p<10-10) can be observed for carbon discrimination afterwards

  3. Stable carbon and nitrogen isotopic compositions of ambient aerosols collected from Okinawa Island in the western North Pacific Rim, an outflow region of Asian dusts and pollutants

    Science.gov (United States)

    Kunwar, Bhagawati; Kawamura, Kimitaka; Zhu, Chunmao

    2016-04-01

    Stable carbon (δ13C) and nitrogen (δ15N) isotope ratios were measured for total carbon (TC) and nitrogen (TN), respectively, in aerosol (TSP) samples collected at Cape Hedo, Okinawa, an outflow region of Asian pollutants, during 2009-2010. The averaged δ13C and δ15N ratios are -22.2‰ and +12.5‰, respectively. The δ13C values are similar in both spring (-22.5‰) and winter (-22.5‰), suggesting the similar sources and/or source regions. We found that δ13C from Okinawa aerosols are ca. 2‰ higher than those reported from Chinese megacities probably due to photochemical aging of organic aerosols. A strong correlation (r = 0.81) was found between nss-Ca and TSP, suggesting that springtime aerosols are influenced from Asian dusts. However, carbonates in the Asian dusts were titrated with acidic species such as sulfuric acid and oxalic acid during atmospheric transport although two samples suggested the presence of remaining carbonate. No correlations were found between δ13C and tracer compounds (levoglucosan, elemental carbon, oxalic acid, and Na+). During winter and spring, coal burning is significant source in China. Based on isotopic mass balance, contribution of coal burning origin particles to total aerosol carbon was estimated as ca. 97% in winter, which is probably associated with the high emissions in China. Contribution of NO3- to TN was on average 45% whereas that of NH4+ was 18%. These results suggest that vehicular exhaust is an important source of TN in Okinawa aerosols. Concentration of water-soluble organic nitrogen (WSON) is higher in summer, suggesting that WSON is more emitted from the ocean in warmer season whereas inorganic nitrogen is more emitted in winter and spring from pollution sources in the Asian continent.

  4. Strong evidence for terrestrial support of zooplankton in small lakes based on stable isotopes of carbon, nitrogen, and hydrogen

    Science.gov (United States)

    Cole, J.J.; Carpenter, S.R.; Kitchell, J.; Pace, M.L.; Solomon, C.T.; Weidel, B.

    2011-01-01

    Cross-ecosystem subsidies to food webs can alter metabolic balances in the receiving (subsidized) system and free the food web, or particular consumers, from the energetic constraints of local primary production. Although cross-ecosystem subsidies between terrestrial and aquatic systems have been well recognized for benthic organisms in streams, rivers, and the littoral zones of lakes, terrestrial subsidies to pelagic consumers are more difficult to demonstrate and remain controversial. Here, we adopt a unique approach by using stable isotopes of H, C, and N to estimate terrestrial support to zooplankton in two contrasting lakes. Zooplankton (Holopedium, Daphnia, and Leptodiaptomus) are comprised of ???20-40% of organic material of terrestrial origin. These estimates are as high as, or higher than, prior measures obtained by experimentally manipulating the inorganic 13C content of these lakes to augment the small, natural contrast in 13C between terrestrial and algal photosynthesis. Our study gives credence to a growing literature, which we review here, suggesting that significant terrestrial support of pelagic crustaceans (zooplankton) is widespread.

  5. Application of nitrogen and carbon stable isotopes (δ(15N and δ(13C to quantify food chain length and trophic structure.

    Directory of Open Access Journals (Sweden)

    Matthew J Perkins

    Full Text Available Increasingly, stable isotope ratios of nitrogen (δ(15N and carbon (δ(13C are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR using δ(15N, and carbon range (CR using δ(13C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ(15N or δ(13C from source to consumer between trophic levels and among food chains. δ(15N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰, and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ(13C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ(13C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority

  6. Stable isotopes in global change research

    International Nuclear Information System (INIS)

    future decline) of CO2 in the atmosphere, all sources and sinks of this gas must be considered and quantified over space and time. Due to natural fractionation processes, stable isotopes of carbon and also - to a lesser degree - of oxygen have proven to be one of the most valuable tools in understanding the fate of CO2 during photosynthesis, respiration, biomass burning and fossil fuel combustion. The isotopes ratios 13C/12C and 18O/16O must, however, be measured with very high precision over long time periods in the atmosphere and in fossil proxies of ancient atmosphere. Such proxies are for instance the large ice shields over Greenland and Antarctica. From measuring stable isotopes of oxygen in ice at the Vostok station we have complete record of the climate changes of the last 440000 years with dramatic changes of the global temperature through several ice ages. From such studies we have learned that the current warm period that started about 10600 years ago is unusually stable. Most of the time, The earth was colder than today, interrupting by shorter warm periods. CO2 concentration has remained below 300 ppm during the whole time frame covered, compared to 380 ppm today. The presentation will focus on the role of stable isotopes measurements or measurement techniques in our understanding of the changes of the global biogeochemical cycles, in particular the carbon cycle that we are witnessing at present. (author)

  7. Combining Old and New Stable Isotope Techniques to Evaluate the Impact of Conservation Tillage on Soil Organic Carbon Dynamics and Stability

    International Nuclear Information System (INIS)

    Soil organic matter (SOM) is a major carbon pool. It is a crucial factor for soil quality including several soil physical properties and a major nutrient source for crops. It also plays a significant role in the global carbon cycle. Soils can act as a carbon sink or source depending on land use and agricultural management practices. Some practices such as conservation tillage or no-tillage could increase SOM stocks, particularly in the topsoil, but in the long term it remains to be seen if and how this SOM is stabilized (De Clercq et al., 2015; Govaerts et al., 2009). In order to evaluate the sustainability and efficiency of soil carbon sequestration measures and the impact of different management and environmental factors, information on SOM stability and mean residence time (MRT) is required. However, this information on SOM stability and MRT is expensive to determine via radiocarbon dating, precluding a wide spread use of stability measurements in soil science. But alternative methods based on stable carbon and nitrogen isotopes, can provide this information at a fraction of the cost

  8. Chemical and stable carbon isotopic composition of PM2.5 from on-road vehicle emissions in the PRD region and implication for vehicle emission control policy

    Directory of Open Access Journals (Sweden)

    S. Dai

    2014-11-01

    Full Text Available Vehicle emission is a major source of urban air pollution. In recent decade, the Chinese government has introduced a range of policies to reduce the vehicle emission. In order to understand the chemical characteristics of PM2.5 from on-road vehicle emission in the Pearl River Delta (PRD region and to evaluate the effectiveness of control policies on vehicles emission, the emission factors of PM2.5 mass, elemental carbon (EC, organic carbon (OC, water-soluble organic carbon (WSOC, water-soluble inorganic ions (WSII, metal elements, organic compounds and stable carbon isotopic composition were measured in the Zhujiang Tunnel of Guangzhou, the PRD region of China in 2013. Emission factors of PM2.5 mass, OC, EC, and WSOC were 92.4, 16.7, 16.4, and 1.31 mg vehicle−1 km−1 respectively. Emission factors of WSII were 0.016 (F- ~4.17 (Cl- mg vehicle−1 km−1, totally contributing about 9.8% to the PM2.5 emissions. The sum of 27 measured metal elements accounted for 15.2% of the PM2.5 emissions. Fe was the most abundant metal element, with an emission factor of 3.91 mg vehicle−1 km−1. Emission factors of organic compounds including n-alkanes, PAHs, hopanes, and steranes were 91.9, 5.02, 32.0 and 7.59 μg vehicle−1 km−1, respectively. Stable carbon isotopic composition δ13C value was measured and it was −25.0‰ on average. An isotopic fractionation of 3.2‰ was found during fuel combustion. Compared with a previous study in Zhujiang Tunnel in year 2004, emission factors of PM2.5 mass, EC, OC, WSII except Cl-, and organic compounds decreased by 16.0–93.4%, which could be attributed to emission control policy from 2004 to 2013. However, emission factors of most of the metal elements increased significantly, which could be partially attributed to the changes in motor oil additives and vehicle condition. There are no mandatory national standards to limit metal content from vehicle emission, which should be a concern of the government. A

  9. Stable carbon isotope analysis to distinguish biotic and abiotic degradation of 1,1,1-trichloroethane in groundwater sediments

    DEFF Research Database (Denmark)

    Broholm, Mette Martina; Hunkeler, Daniel; Tuxen, Nina;

    2014-01-01

    dechlorination. In all biotic microcosms 1,1,1-TCA was degraded with no apparent increase in the biotic degradation product 1,1-DCA. 1,1,1-TCA degradation was documented by a clear enrichment in 13C in all biotic microcosms, but not in the abiotic control, which suggests biotic or biotically mediated degradation...... not appear to be reductive dechlorination via 1,1-DCA. In the biotic microcosms, the degradation of 1,1,1-TCA occurred under iron and sulfate reducing conditions. Biotic reduction of iron and sulfate likely resulted in formation of FeS, which can abiotically degrade 1,1,1-TCA. Hence, abiotic degradation of 1......,1,1-TCA mediated by biotic FeS formation constitute an explanation for the observed 1,1,1-TCA degradation. This is supported by a high 1,1,1-TCA 13C enrichment factor consistent with abiotic degradation in biotic microcosms. 1,1-DCA carbon isotope field data suggest that this abiotic degradation of 1...

  10. Stable Isotope Signatures of Carbon and Nitrogen to Characterize Exchange Processes and Their Use for Restoration Projects along the Austrian Danube

    International Nuclear Information System (INIS)

    The size and composition of an organic matter pool and its sources is a fundamental ecosystem property of river networks. River ecosystems are known to receive large amounts of terrestrial organic matter from catchments, still the question is to what extent aquatic sources influence riverine food webs or at least some components of these food webs. To identify different sources and their potential biological availability at the ecosystem level, we propose using stable isotope signatures of carbon and nitrogen and their respective elemental ratios. In this study, we used these parameters to evaluate river restoration measures. The target of the restoration was to improve surface connectivity between the main channel of the Danube downstream from Vienna and a side arm system within a floodplain. Analyses of the natural abundance of stable isotopes revealed that the restored side arm system showed distinct differences in the particulate organic matter pool in relation to hydrological connectivity. At low water levels, aquatic sources dominate in the side arm system, while at high water levels riverine organic matter is the dominating source. At medium connectivity levels aquatic sources also prevail in the side arm, thus an export of bio-available organic matter into the main channel can be expected. Based on these measurements, the increased - but hydrologically controlled - phytoplankton production was assessed and through this information, changes in ecosystem function were evaluated. (author)

  11. Combined stable isotope, proteomic, metabolomics, and spatial specific analysis to track carbon flow through a hypersaline phototrophic microbial mat

    Science.gov (United States)

    Moran, J.; Cory, A.; Riha, K. M.; Huang, E. L.; Gritsenko, M. A.; Kim, Y. M.; Metz, T. O.; Lipton, M. S.

    2014-12-01

    Tracking labeled substrates through microbial mat systems can help elucidate carbon dynamics, species interactions, and niche partitioning, but the inherent microbial complexity of these systems makes them difficult to probe with single analytical techniques. Here we use a combination of different tools to track three labeled substrates through a benthic phototrophic mat from Hot Lake. Hot Lake is a hypersaline, meromictic lake located in an endorheic basin in north-central Washington which, despite extreme salinity and seasonal water temperatures (> 55 ˚C), hosts dense, phototrophic benthic microbial mats. Cyanobacteria are the dominant CO2-fixing organisms in the system and we seek to understand the spatial and metabolic controls on how the carbon initially fixed by mat cyanobacteria is transferred to associated heterotrophic populations spread throughout the mat strata. We performed ex situ incubations over a complete diel cycle with 13C labeled bicarbonate, acetate, and glucose. Traditional elemental analysis IRMS provided an estimate of bulk label uptake to total biomass and showed that both bicarbonate and acetate were incorporated only during daylight while glucose uptake was nearly constant through the cycle. Spatially resolved isotope analysis using laser ablation IRMS showed distinctive patterns between the different substrates with bicarbonate having highest uptake in the top third of the mat, acetate uptake focused near the mat's center, and glucose showing similar uptake at all mat depths. Proteomic analysis showed a longer lag in substrate conversion to protein than to biomass and a distinct spike in the number of labeled peptides in the bicarbonate incubation near the end of the diel cycle. Proteomic analysis confirmed that photosynthetic organisms showed the highest rates of label conversion to protein but heterotrophic organisms also incorporated label into their peptides. Metabolomic analysis demonstrated the high conversion of organic substrates

  12. Measuring In Vivo Ureagenesis With Stable Isotopes

    OpenAIRE

    Yudkoff, Marc; Mew, Nicholas Ah; Daikhin, Yevgeny; Horyn, Oksana; Nissim, Ilana; Nissim, Itzhak; Payan, Irma; Tuchman, Mendel

    2010-01-01

    Stable isotopes have been an invaluable adjunct to biomedical research for more than 70 years. Indeed, the isotopic approach has revolutionized our understanding of metabolism, revealing it to be an intensely dynamic process characterized by an unending cycle of synthesis and degradation. Isotopic studies have taught us that the urea cycle is intrinsic to such dynamism, since it affords a capacious mechanism by which to eliminate waste nitrogen when rates of protein degradation (or dietary pr...

  13. [Effects of anthropogenic organic matter inputs on stable carbon and nitrogen isotopes in organisms from microbial food chain in Taihu Lake].

    Science.gov (United States)

    Zeng, Qing-Fei; Kong, Fan-Xiang; Zhang, En-Lou; Tan, Xiao

    2007-08-01

    Stable isotope analyses of carbon and nitrogen were used to evaluate autochthonous versus allochthonous contribution to the main microbial food loop components in the four sampling sites based on different trophic status in Taihu Lake. On average, the delta13 C and delta15 N values of organic matter (OM) sources (bacteria, cladocera, particulate and sedimentary organic matter) and the delta13 C of dissolved inorganic carbon (DIC), which are the main components in microbial food chain, showed the lowest values at estuary location compared with the other three sites, reflecting a strong influence by terrestrially derived nutrients and organic matter. The mean delta13 C value of dissolved organic matter (DOM) that we measured was close to the estimated terrestrial delta13 C - 26 per thousandd, suggesting an allochthonous-derived organic C pool. Particulate organic matter (POM) was supposed to be mainly dominated by algae under the assumption of a constant fractionation from DIC to phytoplankton of 22 per thousand. Cladocera had a lower delta13 C than the average delta13 C of POM (0.2 per thousand) and bacteria (2.5 per thousand), supposing a lipid accumulation or selective feeding a more delta13 C-depleted algal fraction (pico- and nano-plankton, isotopes can help to elucidate sources and sinks of organic matter in Taihu Lake, which are characterized by a great spatial variability and complexity. PMID:17926391

  14. Protein labelling with stable isotopes: strategies; Le marquage des proteines aux isotopes stables: strategies

    Energy Technology Data Exchange (ETDEWEB)

    Lirsac, P.N.; Gilles, N.; Jamin, N.; Toma, F.; Gabrielsen, O.; Boulain, J.C.; Menez, A. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Direction des Sciences du Vivant

    1994-12-31

    A protein labelling technique with stable isotopes has been developed at the CEA: a labelled complete medium has been developed, performing as well as the Luria medium, but differing from it because it contains not only free aminated acids and peptides, but also sugars (96% of D-glucopyrannose) and labelled nucleosides. These precursors are produced from a labelled photosynthetic micro-organisms biomass, obtained with micro-algae having incorporated carbon 13, nitrogen 15 and deuterium during their culture. Labelling costs are reduced. 1 fig., 1 tab., 3 refs.

  15. Stable isotope and calcareous nannofossil assemblage records for the Cicogna section: toward a detailed template of late Paleocene and early Eocene global carbon cycle and nannoplankton evolution

    Directory of Open Access Journals (Sweden)

    C. Agnini

    2015-09-01

    Full Text Available We present records of stable carbon and oxygen isotopes, CaCO3 content, and changes in calcareous nannofossil assemblages across an 81 m thick section of upper Paleocene-lower Eocene marine sedimentary rocks now exposed along Cicogna Stream in northeast Italy. The studied stratigraphic section represents sediment accumulation in a bathyal hemipelagic setting from approximately 57.5 to 52.2 Ma, a multi-million-year time interval characterized by perturbations in the global carbon cycle and changes in calcareous nannofossil assemblages. The bulk carbonate δ13C profile for the Cicogna section, once placed on a common time scale, resembles that at several other locations across the world, and includes both a long-term drop in δ13C, and multiple short-term carbon isotope excursions (CIEs. This precise correlation of widely separated δ13C records in marine sequences results from temporal changes in the carbon composition of the exogenic carbon cycle. However, diagenesis has likely modified the δ13C record at Cicogna, an interpretation supported by variations in bulk carbonate δ18O, which do not conform to expectations for a primary signal. The record of CaCO3 content reflects a combination of carbonate dilution and dissolution, as also inferred at other sites. Our detailed documentation and statistical analysis of calcareous nannofossil assemblages show major differences before, during and after the Paleocene Eocene Thermal Maximum. Other CIEs in our lower Paleogene section do not exhibit such a distinctive change; instead, these events are sometimes characterized by variations restricted to a limited number of taxa and transient shifts in the relative abundance of primary assemblage components. Both long-lasting and short-lived modifications to calcareous nannofossil assemblages preferentially affected nannoliths or holococcoliths such as Discoaster, Fasciculithus, Rhomboaster/Tribrachiatus, Spenolithus and Zygrhablithus, which underwent

  16. Stable isotope and calcareous nannofossil assemblage records for the Cicogna section: toward a detailed template of late Paleocene and early Eocene global carbon cycle and nannoplankton evolution

    Science.gov (United States)

    Agnini, C.; Spofforth, D. J. A.; Dickens, G. R.; Rio, D.; Pälike, H.; Backman, J.; Muttoni, G.; Dallanave, E.

    2015-09-01

    We present records of stable carbon and oxygen isotopes, CaCO3 content, and changes in calcareous nannofossil assemblages across an 81 m thick section of upper Paleocene-lower Eocene marine sedimentary rocks now exposed along Cicogna Stream in northeast Italy. The studied stratigraphic section represents sediment accumulation in a bathyal hemipelagic setting from approximately 57.5 to 52.2 Ma, a multi-million-year time interval characterized by perturbations in the global carbon cycle and changes in calcareous nannofossil assemblages. The bulk carbonate δ13C profile for the Cicogna section, once placed on a common time scale, resembles that at several other locations across the world, and includes both a long-term drop in δ13C, and multiple short-term carbon isotope excursions (CIEs). This precise correlation of widely separated δ13C records in marine sequences results from temporal changes in the carbon composition of the exogenic carbon cycle. However, diagenesis has likely modified the δ13C record at Cicogna, an interpretation supported by variations in bulk carbonate δ18O, which do not conform to expectations for a primary signal. The record of CaCO3 content reflects a combination of carbonate dilution and dissolution, as also inferred at other sites. Our detailed documentation and statistical analysis of calcareous nannofossil assemblages show major differences before, during and after the Paleocene Eocene Thermal Maximum. Other CIEs in our lower Paleogene section do not exhibit such a distinctive change; instead, these events are sometimes characterized by variations restricted to a limited number of taxa and transient shifts in the relative abundance of primary assemblage components. Both long-lasting and short-lived modifications to calcareous nannofossil assemblages preferentially affected nannoliths or holococcoliths such as Discoaster, Fasciculithus, Rhomboaster/Tribrachiatus, Spenolithus and Zygrhablithus, which underwent distinct variations in

  17. Estimating groundwater mixing and origin in an overexploited aquifer in Guanajuato, Mexico, using stable isotopes (strontium-87, carbon-13, deuterium and oxygen-18).

    Science.gov (United States)

    Horst, Axel; Mahlknecht, Jürgen; Merkel, Broder J

    2007-12-01

    Stable Isotopes (strontium-87, deuterium and oxygen-18, carbon-13) have been used to reveal different sources of groundwater and mixing processes in the aquifer of the Silao-Romita Valley in the state of Guanajuato, Mexico. Calcite dissolution appeared to be the main process of strontium release leading to relatively equal (87)Sr/(86)Sr ratios of 0.7042-0.7062 throughout the study area which could be confirmed by samples of carbonate rocks having similar Sr ratios (0.7041-0.7073). delta(13)C values (-11.91- -6.87 per thousand VPDB) of groundwaters confirmed the solution of carbonates but indicated furthermore influences of soil-CO(2). Deuterium and (18)O contents showed a relatively narrow range of-80.1- -70.0 per thousand VSMOW and -10.2- -8.8 per thousand, VSMOW, respectively but are affected by evaporation and mixing processes. The use of delta(13)C together with (87)Sr/(86)Sr revealed three possible sources: (i) carbonate-controlled waters showing generally higher Sr-concentrations, (ii) fissure waters with low-strontium contents and (iii) infiltrating water which is characterized by low delta(13)C and (87)Sr/(86)Sr ratios. The third component is affected by evaporation processes taking place before and during infiltration which might be increased by extraction and reinfiltration (irrigation return flow). PMID:18041622

  18. On the isotope fractionation of stable carbon by the example of petroleum from the South-German molasse basin

    International Nuclear Information System (INIS)

    A theoretical model is used to try and explain the 13C/12C isotope fractionation between the hydrocarbon groups of petroleum to clarify its origin. Experimentally found isotope fractionations were compared with those assessed by a Galimov approximation method. The results enable one to group the South-German molasse basin petroleum into four regional groups. (HP)

  19. Pedogenic carbonate stable isotopic evidence for wooded habitat preference of early Pleistocene tool makers in the Turkana Basin.

    Science.gov (United States)

    Quinn, Rhonda L; Lepre, Christopher J; Feibel, Craig S; Wright, James D; Mortlock, Richard A; Harmand, Sonia; Brugal, Jean-Philip; Roche, Hélène

    2013-07-01

    The origin and evolution of early Pleistocene hominin lithic technologies in Africa occurred within the context of savanna grassland ecosystems. The Nachukui Formation of the Turkana Basin in northern Kenya, containing Oldowan and Acheulean tool assemblages and fossil evidence for early members of Homo and Paranthropus, provides an extensive spatial and temporal paleosol record of early Pleistocene savanna flora. Here we present new carbon isotopic (δ(13)CVPDB) values of pedogenic carbonates (68 nodules, 193 analyses) from the Nachukui Formation in order to characterize past vegetation structure and change through time. We compared three members (Kalochoro, Kaitio, and Natoo) at five locations spanning 2.4-1.4Ma and sampled in proximity to hominin archaeological and paleontological sites. Our results indicate diverse habitats showing a mosaic pattern of vegetation cover at each location yet demonstrate grassland expansion through time influenced by paleogeography. Kalochoro floodplains occurred adjacent to large river systems, and paleosols show evidence of C3 woodlands averaging 46-50% woody cover. Kaitio habitats were located along smaller rivers and lake margins. Paleosols yielded evidence for reduced portions of woody vegetation averaging 34-37% woody cover. Natoo environments had the highest percentage of grasslands averaging 21% woody cover near a diminishing Lake Turkana precursor. We also compared paleosol δ(13)CVPDB values of lithic archaeological sites with paleosol δ(13)CVPDB values of all environments available to hominins at 2.4-1.4Ma in the Nachukui and Koobi Fora Formations. Grassy environments became more widespread during this interval; woody canopy cover mean percentages steadily decreased by 12%. However, significantly more wooded savanna habitats were present in the vicinity of lithic archaeological sites and did not mirror the basin-wide trend of grassland spread. Hominin lithic archaeological sites consistently demonstrated woody cover

  20. Sources and fate of organic carbon and nitrogen from land to ocean: Identified by coupling stable isotopes with C/N ratio

    Science.gov (United States)

    Li, Yuan; Zhang, Haibo; Tu, Chen; Fu, Chuancheng; Xue, Yong; Luo, Yongming

    2016-11-01

    The transport of organic matter in coastal areas plays an important role in global biogeochemical cycles. The present study used stable isotopes including carbon (δ13C) and nitrogen (δ15N) and C/N ratio to assess the sources and fate of organic carbon and nitrogen in soils and sediments of a coastal plain-river plume-bay system. Changes of the δ13C and δ15N values from natural to agricultural soils in the Yellow River coastal plain reflected the contribution of C4 carbon, decomposition of organic matter and application of nitrogen fertilizer. The organic carbon in the marine sediments adjacent to the coastal plain mainly originated from C3-dominated terrestrial systems. The spatial heterogeneity of both δ13C and δ15N values indicated that Yellow River sediment transport and anthropogenic wastewater discharge were two driving forces for the sedimentary organic carbon and nitrogen dynamics in large river plume and inner bay areas. Meanwhile, the marine primary production and denitrification process as affected by excessive nutrient input also contributed to the cycling of organic matter. Wetland soils, cropland soils, vegetable soils, coastal and deep-sea sediments were the five systems controlling the cycle of organic carbon and nitrogen in the study area. A significant positive correlation between δ13C and δ15N in the Yellow River coastal plain-plume-bay region was observed, which implied the flux of organic matter from a labile pool in source regions into a more recalcitrant pool in sink regions. These findings would provide a better understanding of carbon sequestration in the coastal soil and sediment.

  1. In-situ studies of microbial CH{sub 4} oxidation efficiency in Arctic wetland soils. Applications of stable carbon isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Preuss, Inken-Marie

    2013-07-05

    Arctic wetland soils are significant sources of the climate-relevant trace gas methane (CH{sub 4}). The observed accelerated warming of the Arctic is expected to cause deeper permafrost thawing followed by increased carbon mineralization and CH{sub 4} formation in water-saturated permafrost-affected tundra soils thus creating a positive feedback to climate change. Aerobic CH{sub 4} oxidation is regarded as the key process reducing CH{sub 4} emissions from wetlands, but quantification of turnover rates has remained difficult so far. This study improved the in-situ quantification of microbial CH{sub 4} oxidation efficiency in arctic wetland soils in Russia's Lena River Delta based on stable isotope signatures of CH{sub 4}. In addition to the common practice of determining the stable isotope fractionation during oxidation, additionally the fractionation effect of diffusion, an important gas transport mechanism in tundra soils, was investigated for both saturated and unsaturated conditions. The isotopic fractionation factors α{sub ox} and α{sub diff} were used to calculate the CH{sub 4} oxidation efficiency from the CH{sub 4} stable isotope signatures of wet polygonal tundra soils of different hydrology. Further, the method was used to study the short-term effects of temperature increase with a climate manipulation experiment. For the first time, the stable isotope fractionation of CH{sub 4} diffusion through water-saturated soils was determined with α{sub diff} = 1.001 ± 0.0002 (n = 3). CH{sub 4} stable isotope fractionation during diffusion through air-filled pores of the investigated polygonal tundra soils was α{sub diff} = 1.013 ± 0.003 (n = 18). For the studied sites the fractionation factor for diffusion under saturated conditions α{sub diff} = 1.001 seems to be of utmost importance for the quantification of the CH{sub 4} oxidation efficiency, since most of the CH{sub 4} is oxidized in the saturated part at the aerobic-anaerobic interface. Furthermore

  2. The Effects of Trimethylamine and Organic Matter Additions on the Stable Carbon Isotopic Composition of Methane Produced in Hypersaline Microbial Mat Environments

    Science.gov (United States)

    Kelley, C. A.; Nicholson, B. E.; Beaudoin, C. S.; Detweiler, A. M.; Bebout, B.

    2014-12-01

    Methane production has been observed in a number of hypersaline environments, and it is generally thought that this methane is produced through the use of non-competitive substrates, such as the methylamines, methanol and dimethylsulfide. The stable carbon isotopic composition of the produced methane has suggested that the methanogens are operating under conditions of substrate limitation. We investigated substrate limitation in gypsum-hosted endoevaporite and soft mat hypersaline environments by the additions of trimethylamine, a non-competitive substrate for methanogenesis, and dried microbial mat, a source of natural organic matter. The δ13C values of the methane produced after amendments were compared to those in unamended control vials. At all hypersaline sites investigated, the δ13C values of the methane produced in the amended vials were statistically lower (by 10 to 71 ‰) than the unamended controls, supporting the hypothesis of substrate limitation at these sites. When substrates were added to the incubation vials, the methanogens within the vials fractionated carbon isotopes to a greater degree, resulting in the production of more 13C-depleted methane. Trimethylamine-amended samples produced lower methane δ13C values than the mat-amended samples. This difference in the δ13C values between the two types of amendments could be due to differences in isotope fractionation associated with the dominant methane production pathway (or substrate used) within the vials, with trimethylamine being the main substrate used in the trimethylamine-amended vials. We hypothesize that increased natural organic matter in the mat-amended vials would increase fermentation rates, leading to higher H2 concentrations and increased CO2/H2 methanogenesis.

  3. Carbon and nitrogen stable isotopes of leaves, litter and soils of the coastal Atlantic Forest of Southeast Brazil along an altitudinal range

    Science.gov (United States)

    Lins, S. M.; Della Coletta, L.; Ravagnani, E.; Gragnani, J. G.; Antonio, J.; Mazzi, E. A.; Martinelli, L. A.

    2012-12-01

    In this study the carbon and nitrogen concentrations, and stable carbon (δ13C) and stable nitrogen (δ15N) isotopic composition were determined in samples of Fabaceae and non Fabaceae leaves, litter, and soil samples in two different altitudes (Lowland and Montane Forests) of the coastal Atlantic Forest situated in the Southeast region of Brazil. In both altitudes there were two main differences between Fabaceae and non Fabaceae specimens. Fabaceae had a higher foliar nitrogen content and lower foliar δ15N than non Fabaceae specimens. As a consequence it seems that most of the Fabaceae specimens are fixing nitrogen from the atmosphere in both altitudes. This fact is contrary to most of other studies that found that most Fabaceae are not fixing nitrogen in tropical forests. We speculate that the main reason that Fabaceae are actively fixing nitrogen in the coastal Atlantic Forest is the steepness of the terrain that leads to frequent landslides, causing frequent disturbances of the nitrogen cycle, fostering nitrogen fixation. The main difference between the Lowland and the Montane Forest plots was the higher δ15N in the former in comparison with the later. We speculated that this difference is caused by larger losses of nitrogen by denitrification and riverine output, leading an enriched 15N substrate.

  4. Metabolic studies in man using stable isotopes

    International Nuclear Information System (INIS)

    In this project, stable isotope compounds and stable isotope pharmaceuticals were used (with emphasis on the application of 15N) to study several aspects of nitrogen metabolism in man. Of the many methods available, the 15N stable isotope tracer technique holds a special position because the methodology for application and nitrogen isotope analysis is proven and reliable. Valid routine methods using 15N analysis by emission spectrometry have been demonstrated. Several methods for the preparation of biological material were developed during our participation in the Coordinated Research Programme. In these studies, direct procedures (i.e. use of diluted urine as a samples without chemical preparation) or rapid isolation methods were favoured. Within the scope of the Analytical Quality Control Service (AQCS) enriched stable isotope reference materials for medical and biological studies were prepared and are now available through the International Atomic Energy Agency. The materials are of special importance as the increasing application of stable isotopes as tracers in medical, biological and agricultural studies has focused interest on reliable measurements of biological material of different origin. 24 refs

  5. Stable isotope composition of Earth's large lakes

    Science.gov (United States)

    Jasechko, S.; Gibson, J. J.; YI, Y.; Birks, S. J.; Sharp, Z. D.

    2011-12-01

    Lakes cover about three percent of Earth's continental area. Large lakes can significantly influence lake shore and regional climates by increasing specific humidity during evaporation and by moderating air temperatures. Stable isotopes of oxygen and hydrogen can be used to quantify lake evaporation, providing a supplementary and often cost-advantageous alternative to conventional hydrologic approaches that require over lake monitoring. Further, stable isotopes in lake sediments are an established tool in paleolimnology; however, interpreting changes to a lake's past isotope composition requires a comprehensive understanding of contemporary controls. Here, δ18O and δ2H values of water in modern lakes exceeding roughly five hundred square kilometres are compiled (n > 35). Voluminous and seasonally mixed lakes - such as the North American Great Lakes - have the most homogenous stable isotope compositions, while perennially-stratified and shallow lakes show greater variability. A rudimentary stable isotope mass balance is used to assess evaporation fluxes from large lakes on Earth. The approach taken simultaneously constrains evaporation outputs for both oxygen and hydrogen stable isotopes by accounting for lake effects on the overlying atmosphere. Model development highlights important considerations such as isotopic stratification (Tanganyika), disequilibrium isotopic mass balances (Baikal), and non-steady hydrologic balances. Further, the isotope composition of Earth's continental surface water reservoir is calculated. This value - weighted to volume - is δ18O = -7.5±1.7 per mille relative to standard mean ocean water. The compiled data may be a useful tracer of continental evaporate in global atmospheric water cycle studies and could be coupled to climate models capable of incorporating oxygen-18 and deuterium tracers to improve or validate calculations of lake effects on regional water cycling.

  6. Stable isotopes on jumbo squid (Dosidicus gigas) beaks to esitmate its trophic positon: comparison between stomach contents and stable isotopes

    OpenAIRE

    Ruiz Cooley, R.I.; Markaida, U.; Gendron, Diane; Aguíñiga García, Sergio

    2006-01-01

    Stomach contents and carbon (C) and nitrogen (N) stable isotope analysis were used to evaluate trophic relationships of jumbo squid, Dosidicus gigas. Buccal masses, beaks and stomach contents of large and medium maturing-sized jumbo squid and muscle from its main prey, the myctophid Benthosema panamense, were collected in the Gulf of California, Mexico during 1996, 1997 and 1999. Both the quantified C and N-isotope ratios in muscle, and stomach content analysis revealed that larger-sized matu...

  7. Effect of varying frontal systems on stable oxygen and carbon isotopic compositions of modern planktic foraminifera of Southern Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Tiwari, M.; Mohan, R.; Meloth, T.; Naik, S.S.; Sudhakar, M.

    sediments yield values akin to that obtained from plankton net samples. It implies that planktic foraminifera preserved in sediments record overlying seawater signatures in this sector. Thus, down-core foraminiferal isotopic data from the Indian sector...

  8. Chemical characterization and stable carbon isotopic composition of particulate polycyclic aromatic hydrocarbons issued from combustion of 10 Mediterranean woods

    Directory of Open Access Journals (Sweden)

    A. Guillon

    2012-08-01

    Full Text Available The objectives of this study were to characterize polycyclic aromatic hydrocarbons from particulate matter emitted during wood combustion and to determine, for the first time, the isotopic signature of PAHs from nine wood species and Moroccan coal from the Mediterranean Basin. In order to differentiate sources of particulate-PAHs, molecular and isotopic measurements of PAHs were performed on the set of wood samples for a large panel of compounds. Molecular profiles and diagnostic ratios were measured by gas chromatography coupled with a mass spectrometer (GC/MS and molecular isotopic compositions (δ13C of particulate-PAHs were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS. Wood species present similar molecular profiles with benz(aanthracene and chrysene as dominant PAHs, whereas levels of concentrations range from 1.8 to 11.4 mg g−1 OC (sum of PAHs. Diagnostic ratios are consistent with reference ratios from literature but are not sufficient to differentiate the different species of woods. Concerning isotopic methodology, PAH molecular isotopic compositions are specific for each species and contrary to molecular fingerprints, significant variations of δ13C are observed for the panel of PAHs. This work allows differentiating wood combustion from others origins of particulate matter (vehicular exhaust using isotopic measurements (with δ13CPAH = −28.7 to −26.6‰ but also confirms the necessity to investigate source characterisation at the emission in order to help and complete source assessment models. These first results on woodburnings will be useful for the isotopic approach of source tracking.

  9. Signature lipids and stable carbon isotope analyses of Octopus Spring hyperthermophilic communities compared with those of Aquificales representatives

    Science.gov (United States)

    Jahnke, L. L.; Eder, W.; Huber, R.; Hope, J. M.; Hinrichs, K. U.; Hayes, J. M.; Des Marais, D. J.; Cady, S. L.; Summons, R. E.

    2001-01-01

    The molecular and isotopic compositions of lipid biomarkers of cultured Aquificales genera have been used to study the community and trophic structure of the hyperthermophilic pink streamers and vent biofilm from Octopus Spring. Thermocrinis ruber, Thermocrinis sp. strain HI 11/12, Hydrogenobacter thermophilus TK-6, Aquifex pyrophilus, and Aquifex aeolicus all contained glycerol-ether phospholipids as well as acyl glycerides. The n-C(20:1) and cy-C(21) fatty acids dominated all of the Aquificales, while the alkyl glycerol ethers were mainly C(18:0). These Aquificales biomarkers were major constituents of the lipid extracts of two Octopus Spring samples, a biofilm associated with the siliceous vent walls, and the well-known pink streamer community (PSC). Both the biofilm and the PSC contained mono- and dialkyl glycerol ethers in which C(18) and C(20) alkyl groups were prevalent. Phospholipid fatty acids included both the Aquificales n-C(20:1) and cy-C(21), plus a series of iso-branched fatty acids (i-C(15:0) to i-C(21:0)), indicating an additional bacterial component. Biomass and lipids from the PSC were depleted in (13)C relative to source water CO(2) by 10.9 and 17.2 per thousand, respectively. The C(20-21) fatty acids of the PSC were less depleted than the iso-branched fatty acids, 18.4 and 22.6 per thousand, respectively. The biomass of T. ruber grown on CO(2) was depleted in (13)C by only 3.3 per thousand relative to C source. In contrast, biomass was depleted by 19.7 per thousand when formate was the C source. Independent of carbon source, T. ruber lipids were heavier than biomass (+1.3 per thousand). The depletion in the C(20-21) fatty acids from the PSC indicates that Thermocrinis biomass must be similarly depleted and too light to be explained by growth on CO(2). Accordingly, Thermocrinis in the PSC is likely to have utilized formate, presumably generated in the spring source region.

  10. Environmental and Physiological Influences on the TEX86 Proxy: Results from Continuous Culture Studies and Stable Carbon Isotope Analyses

    Science.gov (United States)

    Pearson, A.; Hurley, S.; Elling, F. J.; Koenneke, M.; Santoro, A. E.; Buchwald, C.; Wankel, S. D.; Hinrichs, K. U.; Zhang, Y.; Shah Walter, S. R.

    2015-12-01

    Membrane lipids of marine Archaea - known as GDGTs - are the basis of the TEX86 sea surface temperature (SST) paleoproxy. GDGTs are ubiquitous in marine sediments, and their broad distribution and high preservation potential have led to an ever-increasing use of TEX86. The planktonic Thaumarchaeota that are believed to be the major sources of GDGTs to marine sediments are autotrophic nitrifiers, assimilating carbon directly from dissolved CO2. Therefore the δ13C values of GDGTs additionally provide information about the DIC system and paleoproductivity. However, as for all biological proxies, understanding the physiology and biochemistry of the responsible organisms is essential to understanding how the proxies work. From this perspective, the TEX86-SST proxy is uniquely perplexing: How is it possible that multiple approaches to calibration show a good correlation between TEX86 and SSTs, when maximum activity of Thaumarchaeota is near and below the base of the photic zone? Here we show data from two studies that help address this question. Analyses of GDGT δ13C values show that the dominant GDGT flux to sediments is not from the sea surface. The data are measured on intact GDGTs purified by orthogonal dimensions of HPLC, followed by measurement of δ13C values on a Spooling Wire Microcombustion (SWiM)-IRMS with 1σ precision of ±0.2‰ and accuracy of ±0.3‰. Using this approach, we confirm that GDGTs, generally around -19.0‰ to -18.5‰, are isotopically "heavy" compared to other marine lipids, and that crenarchaeol in particular is a good tracer of water column GDGT export. In parallel, we investigated the mechanistic underpinning of the TEX86 proxy using isothermal culture studies of the ammonia-oxidizing thaumarchaeon Nitrosopumilus maritimus SCM1 to explore the relationship between TEX86 and growth conditions. Evidence suggests that growth rate and electron donor supply are important controls on GDGT ratios and that TEX86 scales with the in-situ rate of

  11. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Lepoint, Gilles [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium)]. E-mail: g.lepoint@ulg.ac.be; Dauby, Patrick [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium); Institut Royal des Sciences Naturelles de Belgique, rue Vautier, B1000 Brussels (Belgium); Gobert, Sylvie [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium)

    2004-12-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure of trophic webs in temperate, Mediterranean and tropical seagrass ecosystems. As environmental tracers, stable isotopes have proven their utility in sewage impact measuring and mapping. However, to make such environmental studies more comprehensible, future works on understanding of basic reasons for variations of N and C stable isotopes in seagrasses should be encouraged. At least, as experimental tracers, stable isotopes allow the study of many aspects of N and C cycles at the scale of a plant or at the scale of the seagrass ecosystem.

  12. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems.

    Science.gov (United States)

    Lepoint, Gilles; Dauby, Patrick; Gobert, Sylvie

    2004-12-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure of trophic webs in temperate, Mediterranean and tropical seagrass ecosystems. As environmental tracers, stable isotopes have proven their utility in sewage impact measuring and mapping. However, to make such environmental studies more comprehensible, future works on understanding of basic reasons for variations of N and C stable isotopes in seagrasses should be encouraged. At least, as experimental tracers, stable isotopes allow the study of many aspects of N and C cycles at the scale of a plant or at the scale of the seagrass ecosystem. PMID:15556172

  13. 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.

  14. A new approach to understand methylmercury (CH3Hg) sources and transformation pathways: Compound-specific carbon stable isotope analysis by GC-C-IRMS

    Science.gov (United States)

    Baya, P. A.; Point, D.; Amouroux, D. P.; Lebreton, B.; Guillou, G.

    2015-12-01

    Methylmercury (CH3Hg) is a potent neurotoxin which is readily assimilated by organisms and bio-accumulates in aquatic food webs. In humans, consumption of CH3Hg contaminated marine fish is the major route of mercury exposure. However, our understanding of CH3Hg transformation pathways is still incomplete. To close this knowledge gap, we propose to explore the stable carbon isotopic composition (δ13C) of the methyl group of CH3Hg for a better understanding of its sources and transformation mechanisms. The method developed for the determination of the δ13C value of CH3Hg in biological samples involves (i) CH3Hg selective extraction, (ii) derivatization, and (iii) separation by gas chromatography (GC) prior to analysis by combustion isotope ratio mass spectrometry (C-IRMS). We present the figures of merit of this novel method and the first δ13C signatures for certified materials (ERM-CE464, BCR414) and biological samples at different marine trophic levels (i.e., tuna fish, zooplankton). The implications of this new approach to trace the pathways associated with Hg methylation and the mechanisms involved will be discussed.

  15. Stable carbon isotope fractionation during bacterial acetylene fermentation: Potential for life detection in hydrocarbon-rich volatiles of icy planet(oid)s

    Science.gov (United States)

    Miller, Laurence; Baesman, Shaun; Oremland, Ron

    2015-01-01

    We report the first study of stable carbon isotope fractionation during microbial fermentation of acetylene (C2H2) in sediments, sediment enrichments, and bacterial cultures. Kinetic isotope effects (KIEs) averaged 3.7 ± 0.5‰ for slurries prepared with sediment collected at an intertidal mudflat in San Francisco Bay and 2.7 ± 0.2‰ for a pure culture of Pelobacter sp. isolated from these sediments. A similar KIE of 1.8 ± 0.7‰ was obtained for methanogenic enrichments derived from sediment collected at freshwater Searsville Lake, California. However, C2H2 uptake by a highly enriched mixed culture (strain SV7) obtained from Searsville Lake sediments resulted in a larger KIE of 9.0 ± 0.7‰. These are modest KIEs when compared with fractionation observed during oxidation of C1 compounds such as methane and methyl halides but are comparable to results obtained with other C2compounds. These observations may be useful in distinguishing biologically active processes operating at distant locales in the Solar System where C2H2 is present. These locales include the surface of Saturn's largest moon Titan and the vaporous water- and hydrocarbon-rich jets emanating from Enceladus.

  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. Biogeochemical controls on Diel cycling of stable isotopes of dissolved O2 and dissolved inorganic carbon in the Big Hole River, Montana.

    Science.gov (United States)

    Parker, Stephen R; Poulson, Simon R; Gammons, Christopher H; DeGrandpre, Michael D

    2005-09-15

    Rivers with high biological productivity typically show substantial increases in pH and dissolved oxygen (DO) concentration during the day and decreases at night, in response to changes in the relative rates of aquatic photosynthesis and respiration. These changes, coupled with temperature variations, may impart diel (24-h) fluctuations in the concentration of trace metals, nutrients, and other chemical species. A better understanding of diel processes in rivers is needed and will lead to improved methods of data collection for both monitoring and research purposes. Previous studies have used stable isotopes of dissolved oxygen (DO) and dissolved inorganic carbon (DIC) as tracers of geochemical and biological processes in streams, lakes, and marine systems. Although seasonal variation in 6180 of DO in rivers and lakes has been documented, no study has investigated diel changes in this parameter. Here, we demonstrate large (up to 13%o) cycles in delta18O-DO for two late summer sampling periods in the Big Hole River of southwest Montana and illustrate that these changes are correlated to variations in the DO concentration, the C-isotopic composition of DIC, and the primary productivity of the system. The magnitude of the diel cycle in delta18O-DO was greater in August versus September because of the longer photoperiod and warmer water temperatures. This study provides another biogeochemical tool for investigating the O2 and C budgets in rivers and may also be applicable to lake and groundwater systems.

  18. Stable carbon isotopes and lipid biomarkers provide new insight into the formation of calcite and siderite concretions in organic-matter rich deposits

    Science.gov (United States)

    Baumann, Lydia; Birgel, Daniel; Wagreich, Michael; Peckmann, Jörn

    2015-04-01

    Carbonate concretions from two distinct settings have been studied for their petrography, stable carbon and oxygen isotopes, and lipid biomarker content. Carbonate concretions are in large part products of microbial degradation of organic matter, as for example by sulfate-reducing bacteria, iron-reducing bacteria, and methanogenic archaea. For these prokaryotes certain lipid biomarkers such as hopanoids, terminally-branched fatty acids (bacteria) and isoprenoids (archaea) are characteristic. Two different types of concretions were studied: a) Upper Miocene septarian calcite concretions of the southern Vienna Basin embedded in brackish sediments represented by partly bituminous calcareous sands, silts and clays; b) Paleocene-Eocene siderite concretions enclosed in marine, sandy to silty turbidites with varying carbonate contents and marl layers from the Upper Gosau Subgroup in northern Styria. Calcite concretions consist of abundant calcite microspar (80-90 vol.%), as well as detrital minerals and iron oxyhydroxides. The septarian cracks show beginning cementation with dog-tooth calcite to varying degrees. Framboidal pyrite occurs in some of the calcite concretions, pointing to bacterial sulfate reduction. Siderite concretions consist of even finer carbonate crystals, mainly siderite (40-70 vol.%) but also abundant ferroan calcite, accompanied by iron oxyhydroxides and detrital minerals. The δ13C values of the calcite concretions (-6.8 to -4.1o ) most likely reflect a combination of bacterial organic matter oxidation and input of marine biodetrital carbonate. The δ18O values range from -8.9 to -7.8o agreeing with a formation within a meteoric environment. The surrounding host sediment shows about 1-2o higher δ13C and δ18O values. The siderite δ13C values (-11.1 to -7.5o ) point to microbial respiration of organic carbon and the δ18O values (-3.5 to +2.2o ) agree with a marine depositional environment. In contrast to the calcite concretions, the stable isotope

  19. Stable isotope utilization methodology; Methodologie de l`emploi des isotopes stables

    Energy Technology Data Exchange (ETDEWEB)

    Roth, E. [Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)

    1994-12-31

    The various applications of stable isotope utilization are reviewed, as a function of their specific properties: poly-isotopic abundance modification is used for tracer applications; the accurate measurement of the stable isotope abundance may be applied to isotopic dilution for ultra-trace measurement, physical constant determination, fluid volume and concentration measurement; isotopic effects, such as reaction equilibrium differences are used for separation and identification of molecule active centers (pharmacology, paleoclimatology, hydrogeological studies) while reaction rate differences (competitive and non competitive methods) are used for the study of reaction mechanisms, such as enzymatic reactions. Analysis techniques (mass spectrometry, nuclear magnetic resonance, optical methods) are reviewed. 2 figs., 18 refs.

  20. 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.

  1. A 430 year record of hydroclimate variability for NE-Germany based on stable carbon and oxygen isotopes from pine and oak tree rings

    Science.gov (United States)

    Helle, Gerhard; Baschek, Heiko; Heinrich, Ingo; Navabzadeh, Nadia; Riedel, Frank; Wilmking, Martin; Heußner, Karl-Uwe

    2016-04-01

    European lowlands experience many direct and indirect influences of global warming, particularly related to the hydrological cycle which lately faces increasing flood and drought events. Although important for humans and the ecosystems in which they live, little is known about the long-term spatiotemporal hydrological changes in various European regions. Here we present the first 430-year stable carbon and oxygen chronologies from tree ring cellulose in lowland oak and pine trees (P. sylvestris, Q. petraea) for the region of NE-Germany and provide annually resolved high quality hydroclimatic reconstructions. When compared to ring width data isotope data can be used with only minor adjustments to their means (besides correction of short juvenile trends) and sample depths of 4-5 trees are normally enough for a significant expressed population signal being representative for a site. For this study more than 20 individual tree ring sub-samples for isotopic analyses were obtained from well replicated tree ring chronologies built using living trees as well as historical timber originating from four different lowland sites (50-90m asl.). By a calibration and verification approach we have evaluated the response to instrumental climate and trends of atmospheric partial pressure of CO2 (13C, only) data. While ring widths shows strong correlation to winter temperature, highly significant correlations with summer (JJA) hydroclimate conditions were found for both tree ring 13C and 18O. Strongest relationships were found with summer water vapour pressure deficit (13C and 18O) and Tmax (JJA). Although significant, relationships between 13C and climate data were found considerably weaker than climate/18O relations. On the other hand, the 13C record reveals high similarity with solar irradiance, whereas 18O does not. Based on this profound calibration the presentation will show and discuss annually resolved hydroclimatic variability of the region from our multi-centennial isotope

  2. Benthic trophic network in the Bay of Banyuls-sur-Mer (northwest Mediterranean, France): An assessment based on stable carbon and nitrogen isotopes analysis

    Science.gov (United States)

    Carlier, Antoine; Riera, Pascal; Amouroux, Jean-Michel; Bodiou, Jean-Yves; Grémare, Antoine

    2007-03-01

    The benthic trophic network in the Bay of Banyuls-sur-Mer was studied through the carbon and nitrogen isotopic characterization of a large set of soft-bottom macrobenthic invertebrates, fishes and potential food sources. Continental inputs as well as seagrass meadows did not contribute significantly to this benthic trophic network as indicated by: (1) the difference between their δ 13C signatures (respectively -28.4‰ and -9.5‰) and those of sampled animals (between -21.0‰ and -14.6‰); and (2) their low inputs to the bay. Benthic primary consumers fed mostly on surface sediment organic matter (SSOM), which tightly interacts with suspended particulate organic matter (SPOM) and sedimenting organic matter (STOM) due to sediment resuspension. Our results also suggest the occurrence of a transfer between marine SPOM and some invertebrates (e.g. Veretillum cynomorium) and fishes (e.g. Boops boops and Spicara melanurus) through zooplankton. Moreover, the different types of primary consumers (i.e., suspension-feeders, interface-feeders, surface deposit-feeders and subsurface deposit-feeders) preferentially used distinct fractions of the heterogeneous SPOM-STOM-SSOM pool. These differences were mostly related with feeding depth and resulted in distinct isotopic signatures. Differences in the stable isotopic ratios of suspension and interface-feeders could also partly reflect the use of microphytobenthos by the later. Assuming a 15N-enrichment factor of 3.4‰ between the lower and upper ranges of two successive trophic levels, we estimated that the benthic food web of the Bay of Banyuls-sur-Mer was composed of 4 trophic levels. The comparison with our δ 13C values suggests that the whole trophic food chain is affected by continental inputs at the immediate vicinity of the Rhône River mouth even though these effects are maximal for deposit-feeding and carnivorous polychaetes.

  3. 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.

  4. 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

  5. New 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.

    NARCIS (Netherlands)

    Bijma, Anita

    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 (c

  6. Stable isotope dilution assays in mycotoxin analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rychlik, Michael; Asam, Stefan [Universitaet Muenchen, Lehrstuhl fuer Lebensmittelchemie der Technischen, Garching (Germany)

    2008-01-15

    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis. (orig.)

  7. Interannual Variability in Carbon and Nitrogen Stable Isotopic Signatures of Size-Fractionated POM from the South Florida Coastal Zone

    Science.gov (United States)

    Evans, S. L.; Anderson, W. T.; Jochem, F. J.; Fourqurean, J. W.

    2004-12-01

    Environmental conditions in South Florida coastal waters have been of local and national concern over the past 15 years. Attention has focused on the ecosystem impacts of salinity increases, seagrass die-off, increased algal bloom frequency, waste water influence, groundwater discharge, and exchange between Florida Bay, the Gulf of Mexico, and the Atlantic Ocean. Changes in water quality and productivity levels may be reflected in the isotopic signatures of coastal zone primary producers. Recent work with seagrasses in South Florida has demonstrated high seasonal and spatial variability in C and N isotopic signatures and decoupling between the two isotopic systems as they vary. To better understand the sources of seasonal and spatial fluctuation, size fractionated POM (particulate organic matter) samples have been collected on a quarterly basis since Sept. 2002. Fractions collected include >150μ m, 50-150μ m, and 0.1-50μ m using Nitex mesh sieves and a portable pump system deployed from a small boat at 10 sites around the Florida Keys and Florida Bay. It was hypothesized that planktonic groups respond more quickly to changes in water quality then seagrasses, and thus variations may be more clearly attributed to environmental parameters. Significant spatial and temporal variability is evident both within site between size fractions and between sites. Seasonal oscillations of up to 4‰ were observed in N isotopic values and 6‰ in C isotopic values of the 50-150μ m size fraction, which is dominated by diatoms and dinoflagellates. δ 13C values are depleted in the late winter/early spring sampling period possibly reflecting decreased productivity stress on available C pools. 13C depletion is generally coincident with δ 15N enrichment in the late winter/early spring, possibly demonstrating changes in DIN pools (NO3- and NH4+ concentrations) or changes in decomposition or denitrification rates. Broad groupings appear to separate Atlantic coral reef sites

  8. Stable-Isotopic Analysis of Porcine, Bovine, and Ovine Heparins

    Science.gov (United States)

    Jasper, John P.; Zhang, Fuming; Poe, Russell B.; Linhardt, Robert J.

    2014-01-01

    The assessment of provenance of heparin is becoming a major concern for the pharmaceutical industry and its regulatory bodies. Batch-specific [carbon (δ13C), nitrogen (δ15N), oxygen (δ18O), sulfur (δ34S), and hydrogen (δD)] stable-isotopic compositions of five different animal-derived heparins were performed. Measurements readily allowed their differentiation into groups and/or subgroups based on their isotopic provenance. Principle component analysis showed that a bivariate plot of δ13C and δ18O is the best single, bivariate plot that results in the maximum discrimination ability when only two stable isotopes are used to describe the variation in the data set. Stable-isotopic analyses revealed that (i) stable-isotope measurements on these highly-sulfated polysaccharide (MW ~15 kDa) natural products (“biologics”) were feasible; (ii) in bivariate plots, the δ13C versus δ18O plot reveals a well-defined relationship for source differentiation of hogs raised in the US from hogs raised in Europe and China; (iii) the δD versus δ18O plot revealed the most well-defined relationship for source differentiation based on the hydrologic-environmental isotopes of water (D/H and 18O/16O), and (iv) the δ15N versus δ18O and δ34S versus δ18O relationships are both very similar, possibly reflecting the food sources used by the different heparin producers. PMID:25186630

  9. Carbon transformation and the sources of dissolved inorganic carbonate in sediments of a temperate coastal sea, the Baltic Sea: A stable isotope and modelling approach

    Science.gov (United States)

    Lipka, Marko; Liu, Bo; Wegwerth, Antje; Dellwig, Olaf; Winde, Vera; Al-Raei, Abdul M.; Böttcher, Michael E.

    2015-04-01

    Organic matter is mineralized in brackish-marine sediments by microbial activity using predominantly and sulfate as electron acceptors. Under anoxic bottom water conditions, sulfate reduction dominates. Pore water profiles reflect net biogeochemical processes, transformation rates and fluxes of dissolved species across the sediment-water interface. Element fluxes across the sediment-water interface are controlled by different boundary conditions. We present the results of a detailed biogeochemical investigation of interstitial waters from different sediments of the Baltic Sea covering the range of sedimentological and bottom water redox conditions. It was the aim to study the biogeochemical transformation processes and associated element fluxes at the sediment-water-interface and the role of organic matter or methane as potential substrates for microbial activity. Short sediment cores were collected during several research cruises with multicoring devices. Pore waters were analyzed for nutrients, major and trace element concentrations to allow a modelling of net volumetric transformation rates and diffusive element fluxes. Gross sulfate reduction rates were measured in selected cores using incubations with radiotracer. As a tracer for the source of dissolved inorganic carbonate (DIC) the carbon isotope composition was measured. A quantitative interpretation of vertical concentration profiles in the pore waters was performed using different modelling approaches. Element fluxes across the sediment-water interface show a dependence from bottom water redox conditions, sediment compositions, and sedimentation conditions. It is shown that the carbon isotope composition of DIC is a valuable and sensitive parameter in a model-based estimate of the impact of biological and physical mixing of surface sediments. Research is supported by German BMBF within the KÜNO-SECOS project and Leibniz IOW

  10. Stable isotopes of oxygen and carbon compositions in the Neoproterozoic of South Gabon (Schisto-Calcaire Subgroup, Nyanga Basin): Are cap carbonates and lithoherms recording a particular destabilization event after the Marinoan glaciation?

    Science.gov (United States)

    Préat, Alain; Prian, Jean-Pierre; Thiéblemont, Denis; Obame, Rolf Mabicka; Delpomdor, Franck

    2011-06-01

    Geologic evidence of tropical sea level glaciation in the Neoproterozoic remains a matter of debate in the Snowball Earth hypothesis. The Niari Tillite Formation and the cap carbonates record the late Neoproterozoic Marinoan glaciation in South Gabon. These cap carbonates are located at the base of the Schisto-Calcaire Subgroup a predominantly carbonate succession that rests with sharp contact on top of the Niari Tillite. Integrating sedimentological and stable isotope data, a consistent sequence of precipitation events is proposed, with strongly negative δ 13C values pointing to a particular event in the cap carbonates (average δ 13C value = -3.2‰ V-PDB) and in a further newly defined lithohermal unit (average δ 13C value = -4.6‰ V-PDB). Subsequent shallow evaporitive platform carbonates display carbon and oxygen isotopic compositions indicative of relatively unaltered seawater values. Strongly negative δ 18O values in the lithoherms and replacement of aragonite fans by equigranular calcite suggest flushing of meteoric water derived from glacial meltwater.

  11. Innovative method for carbon dioxide determination in human postmortem cardiac gas samples using headspace-gas chromatography–mass spectrometry and stable labeled isotope as internal standard

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •We developed a method for CO2 analysis in cardiac samples and quantification by 13CO2. •This method was fully validated by accuracy profile. •We have applied this method to perform CO2 precise quantification for forensic applications. •Context of the death could be documented following CO2 concentrations. -- Abstract: A novel approach to measure carbon dioxide (CO2) in gaseous samples, based on a precise and accurate quantification by 13CO2 internal standard generated in situ is presented. The main goal of this study was to provide an innovative headspace-gas chromatography–mass spectrometry (HS-GC–MS) method applicable in the routine determination of CO2. The main drawback of the GC methods discussed in the literature for CO2 measurement is the lack of a specific internal standard necessary to perform quantification. CO2 measurement is still quantified by external calibration without taking into account analytical problems which can often occur considering gaseous samples. To avoid the manipulation of a stable isotope-labeled gas, we have chosen to generate in situ an internal labeled standard gas (13CO2) on the basis of the stoichiometric formation of CO2 by the reaction of hydrochloric acid (HCl) with sodium hydrogen carbonate (NaH13CO3). This method allows a precise measurement of CO2 concentration and was validated on various human postmortem gas samples in order to study its efficiency

  12. Bimodality in stable isotope composition facilitates the tracing of carbon transfer from macrophytes to higher trophic levels

    NARCIS (Netherlands)

    Mendonca, R.; Kosten, S.; Lacerot, G.; Mazzeo, N.; Roland, F.; Ometto, J.P.; Paz, A.; Bueno, O.C.; Gomes, A.C.M.M.; Scheffer, M.

    2013-01-01

    Even though the suitability of macrophytes to act as a carbon source to food webs has been questioned by some studies, some others indicate that macrophyte-derived carbon may play an important role in the trophic transfer of organic matter in the food web of shallow lakes. To evaluate the importance

  13. Signature Lipids and Stable Carbon Isotope Analyses of Octopus Spring Hyperthermophilic Communities Compared with Those of Aquificales Representatives

    OpenAIRE

    Jahnke, Linda L.; Eder, Wolfgang; Huber, Robert; Hope, Janet M.; Hinrichs, Kai-Uwe; Hayes, John M.; Des Marais, David J.; Cady, Sherry L.; Summons, Roger E.

    2001-01-01

    The molecular and isotopic compositions of lipid biomarkers of cultured Aquificales genera have been used to study the community and trophic structure of the hyperthermophilic pink streamers and vent biofilm from Octopus Spring. Thermocrinis ruber, Thermocrinis sp. strain HI 11/12, Hydrogenobacter thermophilus TK-6, Aquifex pyrophilus, and Aquifex aeolicus all contained glycerol-ether phospholipids as well as acyl glycerides. The n-C20:1 and cy-C21 fatty acids dominated all of the Aquificales...

  14. Stable-Carbon-Isotope Composition of Fatty Acids in Hydrothermal Vent Mussels Containing Methanotrophic and Thiotrophic Bacterial Endosymbionts

    OpenAIRE

    Pond, David W; Bell, Michael V; Dixon, David R.; Fallick, Anthony E.; Segonzac, Michel; Sargent, John R.

    1998-01-01

    Fatty acid biomarker analysis coupled with gas chromatography-isotope ratio mass spectrometry was used to confirm the presence of methanotrophic and thiotrophic bacterial endosymbionts in the tissues of a hydrothermal vent mussel (Bathymodiolus sp.), collected from the Menez Gwen vent field on the mid-Atlantic ridge. Monounsaturated (n-8) fatty acids, which are diagnostic of methanotrophic bacteria, were detected in all three types of tissues examined (gill, posterior adductor, and mantle), a...

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

    Science.gov (United States)

    Dubbert, Maren; Piayda, Arndt; Cuntz, Matthias; Correia, Alexandra C.; Costa e Silva, Filipe; Pereira, Joao S.; Werner, Christiane

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Maren eDubbert

    2014-10-01

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

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

    Science.gov (United States)

    Dubbert, Maren; Piayda, Arndt; Cuntz, Matthias; Correia, Alexandra C; Costa E Silva, Filipe; Pereira, Joao S; Werner, Christiane

    2014-01-01

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

  18. [Distribution characteristics of soil humus fractions stable carbon isotope natural abundance (delta 13C) in paddy field under long-term ridge culture].

    Science.gov (United States)

    Tang, Xiao-hong; Luo, You-jin; Ren, Zhen-jiang; Lü, Jia-ke; Wei, Chao-fu

    2011-04-01

    A 16-year field experiment was conducted in a ridge culture paddy field in the hilly region of Sichuan Basin, aimed to investigate the distribution characteristics of stable carbon isotope natural abundance (delta 13C) in soil humus fractions. The soil organic carbon (SOC) content in the paddy field under different cultivation modes ranked in the order of wide ridge culture > ridge culture > paddy and upland rotation. In soil humus substances (HS), humin (HU) was the main composition, occupying 21% - 30% of the total SOC. In the extracted soil carbon, humic acid (HA) dominated, occupying 17% - 21% of SOC and 38% - 65% of HS. The delta 13C value of SOC ranged from -27.9 per thousand to -25.6 per thousand, and the difference of the delta 13C value between 0-5 cm and 20-40 cm soil layers was about 1.9 per thousand. The delta 13C value of HA under different cultivation modes was 1 per thousand - 2 per thousand lower than that of SOC, and more approached to the delta 13C value of rapeseed and rice residues. As for fulvic acid (FA), its delta 13C value was about 2 per thousand and 4 per thousand higher than that of SOC and HA, respectively. The delta 13C value of HU in plough layer (0-20 cm) and plow layer (20-40 cm) ranged from -23.7 per thousand - -24.9 per thousand and -22.6 per thousand - -24.2 per thousand, respectively, reflecting the admixture of young and old HS. The delta 13C value in various organic carbon fractions was HU>FA>SOC>rapeseed and rice residues>HA. Long-term rice planting benefited the increase of SOC content, and cultivation mode played an important role in affecting the distribution patterns of soil humus delta 13C in plough layer and plow layer.

  19. Stable isotope composition of human fingernails from Slovakia

    International Nuclear Information System (INIS)

    Stable isotope composition of human fingernails has proven to be useful for documenting human dietary information and geographical patterns in archeological, forensic, anthropological and biological studies. Therefore, it is of interest to detect all factors influencing the stable isotopic composition in the certain regions in the world. Carbon and nitrogen isotope data of human fingernail keratin from 52 individuals from Slovakia were reported in this study. The online combustion and continuous flow isotope-ratio mass spectrometer Delta V Advantage was used for δ13C and δ15N analysis of fingernail keratin samples from 24 vegetarian and 28 omnivorous individuals. A group of people with frequent meat consumption showed enrichment in 13C and 15N isotopes in fingernails. A similar trend was observed with increasing seafood in an individual's diet. Moreover a significant difference was revealed between smokers and nonsmokers for both δ13C and δ15N values. These data were compared to previously published δ13C and δ15N fingernail values from across the globe. This study brings new information on the stable isotope signature of individuals from Slovakia and characterizes the Central European region for the first time. The stable isotope composition of fingernails is influenced by the frequency of meat and seafood consumption as well as smoking. - Highlights: • This study deals with stable isotope analyses of fingernails from Slovak volunteers. • δ13C and δ15N values of vegetarian and omnivore fingernails were compared. • Influence of sex, diet and smoking was studied

  20. Stable isotope composition of human fingernails from Slovakia

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-15

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

  1. Diurnal variations of organic molecular tracers and stable carbon isotopic composition in atmospheric aerosols over Mt. Tai in the North China Plain: an influence of biomass burning

    Directory of Open Access Journals (Sweden)

    P. Q. Fu

    2012-09-01

    Full Text Available Organic tracer compounds, as well as organic carbon (OC, elemental carbon (EC, water-soluble organic carbon (WSOC, and stable carbon isotope ratios (δ13C of total carbon (TC have been investigated in aerosol samples collected during early and late periods of the Mount Tai eXperiment 2006 (MTX2006 field campaign in the North China Plain. Total solvent-extractable fractions were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs. In early June when the field burning activities of wheat straws in the North China Plain were very active, the total identified organics (2090 ± 1170 ng m−3 were double those in late June (926 ± 574 ng m−3. All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88–1210 ng m−3, mean 403 ng m−3 was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude, which could be further transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary

  2. Compound specific stable isotope analysis vs. bulk stable isotope analysis of agricultural food products

    Science.gov (United States)

    Psomiadis, David; Horváth, Balázs; Nehlich, Olaf; Bodiselitsch, Bernd

    2015-04-01

    The bulk analysis of stable isotopes (carbon, nitrogen, sulphur, oxygen and hydrogen) from food staples is a common tool for inferring origin and/or fraud of food products. Many studies have shown that bulk isotope analyses of agricultural products are able to separate large geographical areas of food origin. However, in micro-localities (regions, districts, and small ranges) these general applications fail in precision and discriminative power. The application of compound specific analysis of specific components of food products helps to increase the precision of established models. Compound groups like fatty acids (FAMEs), vitamins or amino acids can help to add further detailed information on physiological pathways and local conditions (micro-climate, soil, water availability) and therefore might add further information for the separation of micro-localities. In this study we are aiming to demonstrate the power and surplus of information of compound specific isotope analysis in comparison to bulk analysis of agricultural products (e.g. olive oil, cereal crops or similar products) and discuss the advantages and disadvantages of such (labor intense) analysis methods. Here we want to identify tools for further detailed analysis of specific compounds with high powers of region separation for better prediction models.

  3. Bulk Stable Isotope Analysis of Carbon from Solids and Liquids using an Elemental Analyzer Coupled to a Wavelength-Scanned Cavity Ring-Down Spectrophotometer

    Science.gov (United States)

    Saad, N.; Rella, C.; van Pelt, A.

    2009-04-01

    We report here on the novel employment of a small footprint Wavelength-Scanned Cavity Ring-Down Spectrometer (WS-CRDS) interfaced to an elemental analyzer for the measurement of the bulk isotopic carbon signature in plants and food products. The current system provides an inexpensive alternative with unparalleled ease-of-use as compared to standard methods using the more complex analytical instrumentation of isotope ratio mass spectrometry. A precision of carbon isotopic ratio measurements of less than 1 permil was achieved in minutes of measurement time. Such precision readily distinguishes the isotopic carbon signatures of a variety of environmental and agricultural products from different origins, providing information about food authenticity and climate changes effect on plant physiology.

  4. Molecular and stable carbon isotopic compositions of saturated fatty acids within one sedimentary profile in the Shenhu, northern South China Sea: Source implications

    Science.gov (United States)

    Zhu, Xiaowei; Mao, Shengyi; Wu, Nengyou; Sun, Yongge; Guan, Hongxiang

    2014-10-01

    This study examined the distributions and stable carbon isotopic compositions of saturated fatty acids (SaFAs) in one 300 cm long sedimentary profile, which was named as Site4B in Shenhu, northern South China Sea. The concentrations of total SaFAs in sediments ranged from 1.80 to 10.16 μg/g (μg FA/g dry sediment) and showed an even-over-odd predominance in the carbon chain of C12 to C32, mostly with n-C16 and n-C18 being the two major components. The short-chain fatty acids (ScFAs; n-C12 to n-C18) mainly from marine microorganisms had average δ13C values of -26.7‰ to -28.2‰, whereas some terrigenous-sourced long-chain fatty acids (LcFAs; n-C21 to n-C32) had average δ13C values of -29.6‰ to -34.1‰. The other LcFAs (n-C24 & n-C26 ∼ n-C28; average δ13C values are -26.1‰ to -28.0‰) as well as n-C19 and n-C20 SaFAs (average δ13C values are -29.1‰ and -29.3‰, respectively) showed a mixed signal of carbon isotope compositions. The relative bioproductivity calculation (marine vs. terrigenous) demonstrated that most of organic carbon accumulation throughout the sedimentary profile was contributed by marine organism. The high marine productivity in Shenhu, South China Sea may be related to the hydrocarbon seepage which evidenced by diapiric structures. Interestingly, there is a sever fluctuation of terrigenous inputs around the depth of 97 cm below the seafloor (bsf), probably resulting from the influence of the Dansgaard-Oeschger events and the Younger Dryas event as revealed by 14C age measurements.

  5. Analysis of biomagnification of persistent organic pollutants in the aquatic food web of the Mekong Delta, South Vietnam using stable carbon and nitrogen isotopes.

    Science.gov (United States)

    Ikemoto, Tokutaka; Tu, Nguyen Phuc Cam; Watanabe, Michio X; Okuda, Noboru; Omori, Koji; Tanabe, Shinsuke; Tuyen, Bui Cach; Takeuchi, Ichiro

    2008-05-01

    The present study elucidated the biomagnification profiles of persistent organic pollutants (POPs) through a tropical aquatic food web of Vietnam based on trophic characterization using stable nitrogen analysis. Various biological samples collected from the main stream of the Mekong Delta were provided for the analysis for both POPs, and stable nitrogen and carbon isotope ratios. Of the POPs analyzed, dichlorodiphenyltrichloroethane and its metabolites (DDTs) were the predominant contaminants with concentrations ranging from 0.058 to 12 ng/g wet weight, followed by polychlorinated biphenyls (PCBs) at 0.017-8.9 ng/g, chlordane compounds (CHLs) at 0.0043-0.76 ng/g, tris-4-chlorophenyl methane (TCPMe) at N.D.-0.26 ng/g, hexachlorocyclohexane isomers (HCHs) at N.D.-0.20 ng/g and hexachlorobenzene (HCB) at 0.0021-0.096 ng/g. Significant positive increases of concentrations in DDTs, CHLs, and TCPMe against the stable nitrogen ratio (delta(15)N) were detected, while, concentrations of HCHs and HCB showed no significant increase. The slopes of the regression equations between the log-transformed concentrations of these POPs and delta(15)N were used as indices of biomagnification. The slopes of the POPs for which positive biomagnification was detected ranged from 0.149 to 0.177 on a wet weight basis. The slopes of DDTs and CHLs were less than those reported for a marine food web of the Arctic Ocean, indicating that less biomagnification had occurred in the tropical food web. Of the isomers of CHLs, unlike the studies of the Arctic Ocean, oxychlordane did not undergo significant biomagnification through the food web of the Mekong Delta. This difference is considered to be due to a lack of marine mammals, which might metabolize cis- and trans-chlordane to oxychlordane, in the Mekong Delta ecosystem. The biomagnification profile of TCPMe is reported for the first time in the present study. PMID:18313720

  6. 气相色谱-燃烧-同位素比值质谱法测定单体氨基酸的碳稳定同位素组成%Analysis of Stable Carbon Isotope Composition of Individual N-Trifluoroacetyl-Isopropyl Amino Acid Esters by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    蔡德陵; 刘金钟; 刘海珍

    2004-01-01

    A combined gas chromatography combustion-isotope ratio mass spectrometry method(GC-C IRMS) for stable carbon isotope analysis of amino acids is presented. Unlike hydrocarbons, amino acids require derivatization prior to GC-C-IRMS analysis. Replicate carbon isotope analyses of trifluoroacetyl isopropyl ester derivatives of 17 amino acids by IRMS revealed that the derivatization process is reproducible. Due to a reproducible isotopic fractionation an empirical correction factor for each individual amino acid is derived separately for derivatives and the original δ13C value of the underivatized amino acid is calculated.

  7. Stable Vanadium Isotope Fractionation at High Temperatures

    Science.gov (United States)

    Prytulak, J.; Parkinson, I. J.; Savage, P. S.; Nielsen, S. G.; Halliday, A. N.

    2011-12-01

    Vanadium is a redox sensitive transition metal existing in multiple valence states at terrestrial conditions. Stable vanadium isotopes (reported as δ51V in % relative to an Alfa Aesar standard [1]) are a potentially powerful tracer of oxidation-reduction processes. However, the determination of δ51V is analytically challenging, primarily due to the extreme abundance ratio between the only two stable isotopes (51V/50V ~ 400) and, also, significant isobaric interferences of 50Ti and 50Cr on the minor 50V isotope. We have developed the first method able to determine δ51V to a precision (2 s.d. ~ 0.15%, [1,2]) that enables application of this isotope system to geological processes. To usefully investigate high temperature processes using vanadium isotopes, knowledge of the isotope composition and range of values present in the ambient mantle is required. Here we discuss the first δ51V measured in igneous materials encompassing peridotites, MORB, and primitive mantle-derived melts such as picrites. This first dataset provides a preliminary reconnaissance of the magnitude of natural fractionation. We find little isotope fractionation in suites of peridotites and MORB (vanadium isotope fractionation that may be expected at high temperatures. The presence of significant isotope variation outside of analytical precision in these materials bodes well for the use of δ51V to address a variety of broad scale questions in high temperature planetary processes. [1] Nielsen, S.G., Prytulak, J., Halliday, A.N. 2011. Geost. Geoanal. Res., in press. [2] Prytulak, J., Nielsen, S.G., Halliday, A.N. 2011. Geost. Geoanal. Res., in press. [3] Parkinson and Pearce, 1998. Journal of Petrology, 39, 1577-1618. [4] Lee et al., 2005. Journal of Petrology, 46, 2313-2336. [5] Cottrell and Kelley, 2011. Earth and Planetary Sciences Letters, 305, 270-282.

  8. Evaluation of the newly proposed vitamin A supplementation regimen for postpartum mothers using stable carbon isotopes. Highlights and achievements

    International Nuclear Information System (INIS)

    Vitamin A deficiency is a major public health program in many developing countries and has even been identified in the lower socioeconomic groups in the United States. Because serum retinol concentrations are homeostatically controlled and can be depressed by infection, other indicators of vitamin A status have been developed. To this end, we will apply two sensitive indicators of vitamin A status, the modified relative dose response (MRDR) test and the 13C2-retinol isotope dilution assay to a program in Ghana designed to improve total body reserves of vitamin A in lactating women

  9. Water column distribution of stable isotopes and carbonate properties in the South-eastern Levantine basin (Eastern Mediterranean): Vertical and temporal change

    Science.gov (United States)

    Sisma-Ventura, G.; Yam, R.; Kress, N.; Shemesh, A.

    2016-06-01

    Water column distributions of the oxygen isotopic composition of sea-water (δ18OSW) and the stable carbon isotope ratio of dissolved inorganic carbon (δ13CDIC), total alkalinity (AT) and the pH (total scale) at 25 °C (25 °CpHTotal) were investigated along the Southeast Mediterranean (SE-Med) shelf and open water, during 2009-2010. While, the vertical profiles of δ18OSW lacked a clear depth signature, those of δ13CDIC were characterized by a structure that reflects the major water masses in the Levantine basin, with noticeable vertical gradients. The δ13CDIC Suess effect of the Levantine water column was estimated from the difference between the average profiles of 1988 and 2009-2010 (Δδ13CDIC). We observed δ13CDIC temporal change, which indicates propagation of anthropogenic CO2 (Cant) to depth of about 700 m. The Modified Atlantic Water (MAW; 0-200 m) and the Levantine Intermediate Water (LIW; 200-400 m) exhibited a depletion rate of - 0.13 ± 0.03 and - 0.11 ± 0.03‰ decade- 1, respectively, representing ~ 50% of the atmospheric change, while the deep water of the Adriatic source (700-1300 m) did not change during this period. A Δδ13CDIC depletion trend was also recognized below 1350 m, corresponding to the Aegean source deep water (EMDWAeg) and therefore associated to the Eastern Mediterranean Transient (EMT) event. Anthropogenic CO2 accumulation rate of 0.38 ± 0.12 mol C m- 2 yr- 1 for the upper 700 m of the SE-Med, over the last 22 yr, was estimated on the basis of mean depth-integrated δ13CDIC Suess effect profile. Our results confirm lower accumulation rate than that of the subtropical North Atlantic, resulting due to the super-saturation with respect to CO2 of the well-stratified Levantine surface water. High pCO2 saturation during summer (+ 150 μatm), in oppose to a small degree of under-saturation in winter (- 30 μatm) was calculated from surface water AT and 25 °CpHTotal data. However, the δ13CDIC depletion trend of the LIW and the

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

    Science.gov (United States)

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

    2016-08-01

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

  11. Application of stable carbon isotope analysis to the detection of 17beta-estradiol administration to cattle.

    Science.gov (United States)

    Buisson, C; Hebestreit, M; Weigert, A Preiss; Heinrich, K; Fry, H; Flenker, U; Banneke, S; Prevost, S; Andre, F; Schaenzer, W; Houghton, E; Le Bizec, B

    2005-11-01

    The use of anabolic agents in food producing animals is prohibited within the EU since 1988 (96/22/EC directive). The control of the illegal use of natural steroid hormones in cattle is still an exciting analytical challenge as far as no definitive method and non-ambiguous analytical criteria are available. The ability of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to demonstrate the administration of 17beta-estradiol to bovine has been investigated in this paper. By comparison of 13C/12C isotopic ratio of main urinary estradiol metabolite, i.e. 17alpha-estradiol, with two endogenous reference compounds (ERCs), i.e. dehydroepiandrosterone (DHEA) and 5-androstene-3beta,17alpha-diol, the differentiation of estradiol metabolite origin, either endogenous or exogenous, has been proved to be achievable. After treatment, the delta(13)C(VPDB)-values of 17alpha-estradiol reached -27 per thousand to -29 per thousand, whereas delta13CVPDB-values of DHEA remained between -13 per thousand and -20 per thousand depending on the diet, maize and grass, respectively. A significant difference of delta13CVPDB between ERCs and 17alpha-estradiol was measurable over a period of 2 weeks after estradiol ester administration to the animal. PMID:16233872

  12. Distinguishing wild vs. stocked lake trout (Salvelinus namaycush) in Lake Ontario: Evidence from carbon and oxygen stable isotope values of otoliths

    Science.gov (United States)

    Schaner, T.; Patterson, W.P.; Lantry, B.F.; O'Gorman, R.

    2007-01-01

    We investigated the potential for using carbon and oxygen isotope values of otolith carbonate as a method to distinguish naturally produced (wild) lake trout (Salvelinus namaycush) from hatchery-reared lake trout in Lake Ontario. We determined δ 13C(CaCO3) and δ 18O(CaCO3) values of otoliths from juvenile fish taken from two hatcheries, and of otoliths from wild yearlings. Clear differences in isotope values were observed between the three groups. Subsequently we examined otoliths from large marked and unmarked fish captured in the lake, determining isotope values for regions of the otolith corresponding to the first year of life. Marked (i.e., stocked) fish showed isotope ratios similar to one of the hatchery groups, whereas unmarked fish, (wild fish or stocked fish that lost the mark) showed isotope ratios similar either to one of the hatchery groups or to the wild group. We interpret these data to suggest that carbon and oxygen isotope values can be used to determine the origin of lake trout in Lake Ontario, if a catalogue of characteristic isotope values from all candidate years and hatcheries is compiled.

  13. Stable Isotope Dilution Assays for Clinical Analyses of Folates and Other One-Carbon Metabolites: Application to Folate-Deficiency Studies.

    Science.gov (United States)

    Kopp, Markus; Morisset, Rosalie; Koehler, Peter; Rychlik, Michael

    2016-01-01

    Folate deficiency is generally accepted as a potential direct or indirect risk factor for diseases including spina bifida, coronary heart diseases, malfunctions of the central nervous system, and cancer. The direct inclusion of folates in the methylation cycle, including the remethylation of homocysteine and regeneration of S-adenosylmethionine, underlines the importance of these vitamins and other components of one-carbon metabolism. Therefore, the aim of the present study was to develop a multiple stable isotope dilution assay (SIDA) for the respective analytes in plasma and tissue samples to allow for a closer look at the interaction between a severe folate deficiency and local folate status, as well as further interactions with circulating S-adenosylmethionine, S-adenosylhomocysteine, and homocysteine. The analytical methods were based on SIDAs coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis using the deuterated folates [2H4]-5-methyltetrahydrofolic acid, [2H4]-5-formyltetrahydrofolic acid, [2H4]-tetrahydrofolic acid, [2H4]-10-formylfolic acid, and [2H4]-folic acid and the deuterated one-carbon metabolites [2H4]-homocysteine, [2H4]-S-adenosylhomocysteine, and [2H3]-S-adenosylmethionine as internal standards. Three analytical methods have been developed for the analysis of homocysteine, S-adenosylmethionine, S-adenosylhomocysteine, and six folate vitamers. Validation data for the analysis of C1-metabolites in plasma and tissue samples or folate analysis in tissue samples revealed excellent sensitivity, precision, and recovery for all analytes studied. The miniaturized methods using sample volumes as low as 50 μL and weighed portions of 5-25 mg will allow the assessment of the status of folates and additional biomarkers of impaired one-carbon metabolism during folate deficiency. PMID:27276031

  14. Recent applications of stable isotopes in environmental medicine in germany

    International Nuclear Information System (INIS)

    In the last few years, a new quality in the application of stable isotopes became manifest. It is the establishment of stable isotopes as a tool in medical routine diagnosis - a novel field of nuclear medicine - and in environmental-medical epidemiological surveys. Owing to missing suitable radioactive isotopes of the bio elements carbon and nitrogen and because of ethical problems in the human use of some radionuclides, the stable isotopes 13 C and 1% N play a key role in this new field. A review is given about four new stable isotope-aided methods for in vivo organ function test. Three of them were developed in Leipzig, germany, and one in houston/Texas. We have validated the tests and then introduced into medical and environmental routine diagnostic use: (15 N Methacetin and (13C) methacetin liver function tests to characterize the detoxification capacity of the human liver; (15N) Urea and (13C) urea tests to detect the colonization of the human stomach by the bacterium helicobacter pylori. This bacterium is, as known, responsible for gastritis and ulcer of the gastrointestinal tract. The transmission ways of H. Pylori are under investigation world-wide

  15. Utilization of carbon 13-labelled stable isotopes for studying drug toxicity on cellular metabolism; Utilisation d`isotopes stables marques au carbone 13 pour etudier la toxicite de drogues au niveau du metabolisme cellulaire

    Energy Technology Data Exchange (ETDEWEB)

    Herve, M.; Wietzerbin, J.; Tran-Dinh, S. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Biologie Cellulaire et Moleculaire

    1994-12-31

    A new approach for studying the effects of two drugs, amphotericine B (AMB), an anti-fungal antibiotic, and 2-deoxy-D-glucose (DG), on the glucose metabolism in brewer yeast cells (Saccharomyces cerevisiae), is presented; AMB interacts with the membrane sterols, inducing formation of pores through which ions and small molecules can pass. DG may enter in the cytosol, where it is phosphoryled by hexokinase into deoxy-D-glucose 6-phosphate (DG6P) which disappears very slowly. DG slows down the glycolysis process and induces the formation of new substances. This paper shows the advantages of utilizing carbon 13-labelled substrates combined to the NMR-13C and NMR-1H techniques. 6 figs., 5 refs.

  16. 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

  17. Stereoselective synthesis of stable-isotope-labeled amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Unkefer, C.J.; Martinez, R.A.; Silks, L.A. III [Los Alamos National Laboratory, NM (United States); Lodwig, S.N. [Centralia College, WA (United States)

    1994-12-01

    For magnetic resonance and vibrational spectroscopies to reach their full potential, they must be used in combination with sophisticated site-specific stable isotope labeling of biological macromolecules. Labeled amino acids are required for the study of the structure and function of enzymes and proteins. Because there are 20 common amino acids, each with its own distinguishing chemistry, they remain a synthetic challenge. The Oppolzer chiral auxiliary provides a general tool with which to approach the synthesis of labeled amino acids. By using the Oppolzer auxiliary, amino acids can be constructed from several small molecules, which is ideal for stable isotope labeling. In addition to directing the stereochemistry at the {alpha}-carbon, the camphorsultam can be used for stereo-specific isotope labeling at prochiral centers in amino acids. By using the camphorsultam auxiliary we have the potential to synthesize virtually any isotopomer of all of the common amino acids.

  18. Stable isotope enrichment using a plasma centrifuge

    Science.gov (United States)

    Krishnan, Mahadevan; Bures, Brian; Madden, Robert

    2012-10-01

    A primary goal of the Department of Energy's Isotope Development and Production for Research and Applications Program (Isotope Program) within the Office of Nuclear Physics (NP) is to produce isotopes that are in short supply in the U.S. and of which there exists no or insufficient domestic commercial production capability. A vacuum arc plasma centrifuge is a rigid rotor column of metal plasma in which centrifugal forces re-distribute ions radially according to their mass/charge ratio. Early work demonstrated rotation at 2 million rpm and separation of various stable isotopes. The spinning plasma column had a Gaussian flux profile, peaked on the rigid rotor axis. This work adopts a more efficient approach, with the plasma created as a hollow column, wherein the flux is concentrated at larger radii where the centrifugal action is highest. By tailoring the vacuum arc discharge geometry, the rotation rate can also be increased to ˜10 million rpm. Data from Cu, Al and other metal plasmas will be presented and discussed in light of enriched stable isotopes needed for research and medicine.

  19. 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.

  20. Breeding Westland petrels as providers of detrital carbon and nitrogen for soil arthropods : a stable isotope study

    International Nuclear Information System (INIS)

    Seabirds deposit large quantities of marine detritus on land, but little is known of the soil arthropods processing this material. Burrow-nesting seabirds concentrate their activities within their burrows, so we tested the hypothesis that burrow arthropod fauna is more marine-like in its isotopic enrichment (13C/12C, 15N/14N); expressed as δ13C and δ15N) than the arthropods on the adjacent forest floor. Results from a Westland petrel (Procellaria westlandica) colony on the South Island of New Zealand did not support the hypothesis. Instead, δ15N was universally marine (13-22 per mil). While δ13C separated into two clusters, the distribution was not according to arthropod provenance. Most taxa had a terrestrial δ13C; only two taxa (a leiodid beetle and the mesostigmatic mite Ayersacarus woodi) incorporated marine C. The leiodid beetle occurs both in burrows and on the forest floor; beetles from both habitats had a marine δ13C. Ayersacarus woodi is found only in burrows. We conclude that, in this system, marine and terrestrial detrital C is processed separately, and that marine detrital C enters the terrestrial ecosystem through a very few arthropod taxa. (author). 33 refs., 1 fig.

  1. Western Indian Ocean circulation and climate variability on different time scales. A study based on stable oxygen and carbon isotopes, benthic foraminiferal assemblages and Mg/Ca paleothermometry

    Energy Technology Data Exchange (ETDEWEB)

    Romahn, Sarah

    2014-08-19

    In order to understand the Earth's climate evolution it is crucial to evaluate the role of low-latitude oceans in the global climate system, as they are connected to both hemispheres via atmospheric and oceanic circulation and thus hold the potential to disentangle the asynchronicity of short-term Pleistocene climate variability. However, the potential of low latitude oceans to respond to and force large-scale changes of the climate system is still debated. The aim of this thesis is to examine and to understand the causal relationship of both atmospheric and oceanic changes in the tropical western Indian Ocean on centennial-, millennial and glacial-interglacial timescales. For this purpose I investigated stable oxygen and carbon isotope compositions of both planktic and benthic foraminiferal tests, Mg/Ca ratios of planktic foraminiferal tests as well as benthic foraminiferal assemblages and sedimentary geochemical parameters on two sediment cores (GeoB12615-4, 446 m and GeoB12616-4, 1449 m) from the continental slope off Tanzania, East Africa.

  2. Fossil gastropods from the Indian Upper Siwaliks and their stable carbon and oxygen isotope values indicate presence of cold climatic conditions in the Early Pleistocene.

    Science.gov (United States)

    Singh Kotla, Simran

    2016-04-01

    The Early Pleistocene in general is characterized by widespread glaciations in the Northern Hemisphere. Early to Middle Pleistocene freshwater Pinjor Formation (Upper Siwalik) exposed all along the Himalayan Foothills preserves a diverse faunal and floral assemblage. We carried out paleontological (gastropods) and stable isotope (carbon and oxygen isotope) studies of a 6 m thick swamp/pond deposit (that represents ~ 12,000 yrs) of Pinjor Formation, exposed near the Village Nadah, Panchkula (Haryana) and dated to ~ 1.8 Ma (Azzaroli and Napoleon,1982). We have identified four gastropod species in the assemblage, Lymnae sp., Gyraulus sp., Viviparous bengalensis and Hippeutis complantus. The first two are widespread throughout the globe. Lymnae can exist in temperature range of 19 to 24 ° C and occur in Palearctic and Neoartic regions (animalbase.org). Gyraulus occur in Holoarctic region with temperature ranging from 17.8 to 30 ° C (animalbase.org, theaquariumwiki.com), whereas Viviparous bengalensis typically exists in the Oriental region suggesting an overall warm and humid condition (Moore,1997). Hippeutis complantus on the other hand exists in palearctic regions upto 63 ° N (Aplinarska and Cisewka 2006) under cold (6 ° to 23.3 ° C) and dry climatic conditions (Spyra., 2014).The powdered gastropod shell samples were analyzed using Continues Flow Isotope Ratio Mass Spectrometer (CF-IRMS) at the Wadia Institute of Himalayan Geology, Dehradun, India. The δ13C values of gastropod shells fall between -2.56‰ and 6.14‰ VPDB and suggest the dominance of C4 vegetation. The δ18O value of gastropod shell fall between -0.64‰ and -7.80‰ VPDB, suggesting fluctuation of climate between warm and cold conditions . Presence of Hippeutis complantus may suggest the extension of palearctic region up to Panchkula (Haryana, India) in the Early Pleistocene which presently lies in the Oriental Province. Therefore, our results indicate that the overall climatic condition

  3. Stable Isotope Characterization of TICs/TIMs: Analytical Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Volpe, A M; Singleton, M J

    2009-06-05

    We measured twelve alkali cyanide samples that were also sent to ORNL and PNNL collaborators. While results indicate distinct {delta}{sup 13}C and {delta}{sup 15}N values that would be useful to signature studies, the alkali cyanides, especially NaCN, show chemical breakdown during storage that will influence forensic analysis. Carbon and nitrogen stable isotopic compositions of raw materials used to synthesis TETS were measured. Results indicate wide ranges in {delta}{sup 13}C and {delta}{sup 15}N values. Using these raw materials, LLNL scientists synthesized three batches of TETS following published procedures. Stable isotopic measurements of TETS synthesis products indicates nitrogen ({var_epsilon} {sup 15}N = -1.7 to -0.8) and carbon ({var_epsilon} {sup 13}C = -1.0 to -0.1) fractionation during production.

  4. Seasonal variations of stable carbon isotopic ratios and biogenic tracer compounds of water-soluble organic aerosols in a deciduous forest

    Directory of Open Access Journals (Sweden)

    Y. Miyazaki

    2011-11-01

    Full Text Available To investigate the seasonal changes in biogenic water-soluble organic carbon (WSOC aerosols in a boreal forest, aerosol samples were collected continuously in the canopy of a~deciduous forest in Northern Japan during 2009–2010. Stable carbon isotopic ratios of WSOC (δ13CWSOC in aerosols exhibited a distinct seasonal cycle, with lower values from June through September (−25.5 ± 0.5‰. This cycle follows the net CO2 exchange between the forest ecosystem and the atmosphere, indicating that δ13CWSOC likely reflects the biological activity at the forest site. WSOC concentrations showed the highest values in early summer and autumn. Positive matrix factorization (PMF analysis indicated that the factor in which biogenic secondary organic aerosols (BSOAs dominated accounted for ~ 40% of the highest concentrations of WSOC, where BSOAs mostly consisted of α-/β-pinene SOA. In addition, primary biological aerosol particles (PBAPs made similar contributions (~ 57% to the WSOC near the canopy floor in early summer. This finding indicates that the production of both primary and secondary WSOC aerosols is important during the growing season in a deciduous forest. The methanesulfonic acid (MSA maximum was also found in early summer and had a distinct vertical gradient with larger concentrations near the canopy floor. Together with the similar vertical gradients found for WSOC and δ13CWSOCas well as the α-/β-pinene SOA tracers, our results indicate that the forest floor, including ground vegetation and soil, acts as a significant source of the WSOC within a~forest canopy at the study site.

  5. Seasonal variations of stable carbon isotopic composition and biogenic tracer compounds of water-soluble organic aerosols in a deciduous forest

    Directory of Open Access Journals (Sweden)

    Y. Miyazaki

    2012-02-01

    Full Text Available To investigate the seasonal changes in biogenic water-soluble organic carbon (WSOC aerosols in a boreal forest, aerosol samples were collected continuously in the canopy of a deciduous forest in northern Japan during 2009–2010. Stable carbon isotopic composition of WSOC (δ13CWSOC in total suspended particulate matter (TSP exhibited a distinct seasonal cycle, with lower values from June through September (−25.5±0.5 ‰. This cycle follows the net CO2 exchange between the forest ecosystem and the atmosphere, indicating that δ13CWSOC likely reflects the biological activity at the forest site. WSOC concentrations showed the highest values in early summer and autumn. Positive matrix factorization (PMF analysis indicated that the factor in which biogenic secondary organic aerosols (BSOAs dominated accounted for ~40 % of the highest concentrations of WSOC, where BSOAs mostly consisted of α-/β-pinene SOA. In addition, primary biological aerosol particles (PBAPs made similar contributions (~57 % to the WSOC near the forest floor in early summer. This finding indicates that the production of both primary and secondary WSOC aerosols is important during the growing season in a deciduous forest. The methanesulfonic acid (MSA maximum was also found in early summer and had a distinct vertical gradient with larger concentrations near the forest floor. Together with the similar vertical gradients found for WSOC and δ13CWSOC as well as the α-/β-pinene SOA tracers, our results indicate that the forest floor, including ground vegetation and soil, acts as a significant source of WSOC in TSP within a forest canopy at the study site.

  6. anteiso-Fatty Acids in Brussels Sprouts (Brassica oleracea var. gemmifera L.): Quantities, Enantioselectivities, and Stable Carbon Isotope Ratios.

    Science.gov (United States)

    Eibler, Dorothee; Seyfried, Carolin; Kaffarnik, Stefanie; Vetter, Walter

    2015-10-14

    anteiso-Fatty acids (aFAs) are a class of branched-chain fatty acids that are characterized by one methyl branch on the antepenultimate carbon of the straight acyl chain. aFAs are mainly produced by bacteria, and sources in vegetables are scarce. This study reports the concentrations of odd-numbered aFAs (a15:0-a21:0) in Brussels sprout buds. Selective enrichment followed by enantioselective gas chromatography with mass spectrometry in the selected ion monitoring mode revealed that both a15:0 and a17:0 were (S)-enantiopure in Brussels sprout samples. δ(13)C values (‰) of a17:0 in Brussels sprouts were comparable with those of palmitic acid, indicating no different source for both fatty acids. PMID:26390192

  7. Stable isotope composition of food from different regions of Poland

    International Nuclear Information System (INIS)

    Full text: Stable isotope (hydrogen, oxygen, carbon and nitrogen) composition is important tool for food authenticity and control of origin. The isotopic fractionation of those elements in the environment follows complex patterns allowing to established the correlation between the food (fruits, vegetables etc.) and raw materials (water and CO2). The aim of the study is to explore the relationship between isotope composition of different sorts of food and its geographical origin. The purpose of the study is to compare the data from different regions of Poland. The samples are received directly from a producer. Hydrogen, oxygen, nitrogen and carbon composition is measured in many sorts of food. The collected data gives a possibility to find the relationship between time and place of origin and isotope ratio: 18O/16O, 13C/12C, 15N/14N and D/H. The composition of water presented in the food is tested. Hydrogen is measured by H/Device and oxygen isotope ratio by Gasbench II (both instruments connected with mass spectrometer). For the comparison the water samples from the region of plant growing are tested. In this study for measurements of carbon and nitrogen composition in food, we use our new instrument Elemental Analyser coupled with mass spectrometer. The correlation between stable isotope composition 18O/16O, 13C/12C, 15N/14N, D/H and geographical origin of food will be presented in the paper. In the future, the study will be continued and addition of parameters, as a sulfur isotope composition in food and in surrounding environment (as a pollutant), will be compared. (author)

  8. Stable isotope composition of food from different regions of Poland

    International Nuclear Information System (INIS)

    Full text: Stable isotope (hydrogen, oxygen, carbon and nitrogen) composition is an important tool for food authenticity and control of origin. The isotopic fractionation of those elements in the environment follows complex patterns, allowing to establish the correlation between food (fruits, vegetables etc.) and raw materials (water and CO2). The aim of the study is to explore the relationship between isotope composition of different sorts of food and its geographical origin. The purpose of the study is to compare the data from different regions of Poland. The samples are received directly from a producer. Hydrogen, oxygen, nitrogen and carbon composition is measured in many sorts of food. The collected data give a possibility to find the relationship between time and place of origin and isotope ratio: 18O/16O, 13C/12C, 15N/14N and D/H. The composition of water presented in food is tested. Hydrogen is measured by H/Device and oxygen isotope ratio, by Gasbench II (both instruments connected with mass spectrometer). For the comparison the water samples from the region of plant growing are tested. In this study, for measurements of carbon and nitrogen composition in food, we use our new instrument Elemental Analyser coupled with mass spectrometer. The correlation between stable isotope composition 18O/16O, 13C/12C, 15N/14N, D/H and geographical origin of food will be presented in the paper. In the future, the study will be continued and addition of parameters, as a sulfur isotope composition in food and in surrounding environment (as a pollutant), will be compared. (author)

  9. An Approach to Analysis of Stable Isotopes in Microsamples

    Institute of Scientific and Technical Information of China (English)

    韩友科; 安娜

    1991-01-01

    A new aproach to isotopic analysis of carbon,oxygen,sulfur and nitrogen in microsamples has been established.Samples were conventionally prepared by mixing microsamples to be analyzed with reference samples with known δ values in a proper proportion,and then analyzed for their stable isotopes as those at ordinary levels.According to the equilibrium relationships before and after mixing,the δvalues of unknown microsamples were calculated.The δ15N of the atmosphere was estimated at zero by this approach,which is concordant with the internationally recommended value.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-01

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

  11. Late Holocene stable carbon and nitrogen isotopic variation of bulk organic matter deposited in Blackwood Sinkhole, Abaco, The Bahamas

    Science.gov (United States)

    Tamalavage, A.; van Hengstum, P. J.; Louchouarn, P.; Fall, P. L.; Donnelly, J. P.

    2015-12-01

    In the modern climate of the Bahamas, a latitudinal precipitation gradient only allows Pine (Pinus caribaea var. bahamensis) dominated forests to exist on the more mesic (humid) northern islands (Abaco, Andros, New Providence, Grand Bahamas). Previous research suggests that the northern Bahamas underwent dramatic environmental changes in the late Holocene (e.g., waves of human arrival, shifts in terrestrial vegetation and animal extinctions). However, disentangling the timing and relative forcing (climatic vs. anthropogenic) of these changes has proven challenging without high-resolution terrestrial climate records. Recently, a late Holocene decadal to multi-decadal laminated sedimentary record was recovered from Blackwood Sinkhole, on Abaco Island. The bottom of the sinkhole is characterized by anoxic, saline groundwater, while the upper, brackish meteoric lens provides a habitat to fish, algae and other organisms. Here, we present δ13Corg and δ15Norg values of bulk organic matter (OM) taken every cm of the 110 cm core to help elucidate changes in the chemical composition of the source of OM reaching the anoxic sediments of the sinkhole. δ13Corg values change at 812 Cal yrs BP (2s: 931-681 Cal yrs BP, 31.7 cm depth) from -30.5 ± 1.6‰ in the lower 80 cm of the core to -27.6 ± 1.2‰ in the upper 30 cm. There is a synchronous change from more enriched δ15N values, 3.7 ± 1.1‰, in the lower portion of the core, to lower δ15N values (1.9 ± .5‰), in the upper portion of the core. A pollen-based reconstruction of terrestrial vegetation from the same core indicates that these isotopic shifts are concomitant with a shift from a dominance of Arecaceae (Palms) and tropical dry hardwoods below 30 cm, to Pinus and Conocarpus predominance above 30 cm. These results indicate that the source of sedimentary OM deposited into the sinkhole changed coherently with regional landscape change. Biomarker analyses will be used to further identify the role of autochthonous

  12. Stable isotope-based paleoenvironmental reconstructions of Neogene terrestrial archives

    OpenAIRE

    Lüdecke, Tina

    2016-01-01

    The stable isotope geochemistry of pedogenic and lacustrine carbonate and fossil herbivore tooth enamel is a powerful tool to study the evolution of terrestrial paleoenvironments. This thesis aims to reconstruct Neogene ecosystems in the Karonga Basin in the southern part the East African Rift (EAR) and the Central Anatolian Plateau (CAP). Karonga Basin: Understanding the development of East African savanna biomes is crucial for reconstructing the evolution, migration and dietary behaviors...

  13. Stable isotopes in paleosols and origins of the Asian monsoon

    OpenAIRE

    Quade, Jay; Cerling, Thure E.

    1991-01-01

    The stable isotopic composition of buried soil carbonate and organic matter from northern Pakistan and Nepal can be used to reconstruct aspects of the paleoecology of riverine floodplain ecosystems over the past 17 Myr. Probable dry woodland dominated the floodplain biomass of large rivers ancestral to the modern Indus and Ganges up to 7.3 Myr. Between 7.3 and about 6 Myr, tropical grasses gradually displaced woodland and have dominated floodplain biomasses to the present. The paleovegetation...

  14. Stable isotopes for heavy element production

    CERN Document Server

    Lommel, B; Hofmann, S; Kindler, B; Klemm, J; Steiner, J; Tinschert, K

    2003-01-01

    The synthesis of heavy elements and the search for new superheavy elements is one of the exciting fields in modern nuclear physics and chemistry. Heavy elements are produced by heavy-ion fusion reactions. Necessary prerequisites are intense heavy-ion beams from pure isotopic material and thin isotopically enriched targets. At GSI the elements from 107 to 112 were produced using targets of Pb and Bi and beams of the most neutron rich isotopes of Cr, Fe, Ni, and Zn. Experimental set-up consisting of target wheel, velocity filter SHIP (Separator for Heavy Ion Reaction Products), and detector system is presented. Status of the ion source techniques for delivering intense and stable beams for this kind of experiment is shortly described. The manufacturing and properties of various source - target combinations used for the synthesis of the elements by now are discussed in detail as well as the possibilities for extending the experiments into the region of superheavy elements.

  15. Human nutritional studies using stable isotopes

    International Nuclear Information System (INIS)

    Methods using stable isotopes in nutritional studies are very useful for assessing the dynamic movement and availability of nutrients. This report introduces the doubly labeled water (DLW) method and the indicator amino acid oxidation (IAAO) method. The DLW method uses H218O and 2H2O to prec