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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. Stable carbon isotope analysis of bone apatite

    International Nuclear Information System (INIS)

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

  3. Evaluation of bioremediation systems utilizing stable carbon isotope analysis

    International Nuclear Information System (INIS)

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

  4. 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.

  5. 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

  6. 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

  7. 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

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

    Science.gov (United States)

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

    2014-11-01

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

  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. Stable carbon isotopic characterization of hydrocarbons in contaminated soils

    International Nuclear Information System (INIS)

    Effective management of risks at sites featuring refractory hydrocarbon wastes is often constrained by the limitations of conventional analytical methodologies. Stable carbon isotope analysis was therefore evaluated as an alternative means of characterizing the composition, source and weathering of hydrocarbon contaminants. Bulk δ13C of selected heavy oils (boiling range 50 to 500 C) of varying component class distribution decreased from -28.9 to -27.4 per-thousand as oil saturate class content decreased (from 70.6 to 31.7%w/w) and polar/asphaltene content increased (from 7.4 to 50.5%w/w). Class δ13C increased by up to 2.5 per-thousand as follows: saturates (ca. -29 per-thousand) 13C. Plots of oil δ13C vs. saturate and polar/asphaltene content confirmed this relationship, returning linear correlation coefficients (r2) of 0.93 and 0.99, respectively. Characteristic isotopic fingerprints of heavy oils, crude oils and acid tar wastes may also provide a valuable means of differentiating between possible source terms. Unweathered, 25%, 50% and 75% weathered reference oils were analyzed by compound specific isotope analysis (CSIA). n-Alkane (C13-C23) δ13C were often 1--2 per-thousand lower in the weathered samples (e.g., δ13C of C15 = -27.14 per-thousand (fresh), -26.86 per-thousand at 25%, -25.36 per-thousand at 50%, undetected at 75%). CSIA of established oil biomarkers, detected by GC/MS, facilitated the creation of a index for quantifying the extent of weathering undergone. Subsequent work investigating the effects of biotransformation on selected oil δ13C is underway

  13. 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

  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. 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.

  16. 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

  17. 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...

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

    Science.gov (United States)

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

    2013-11-01

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

  19. 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.

  20. 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

  1. 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.

  2. Influence of carbon source on the stable carbon isotopic composition of the seagrass Thalassia testudinum

    International Nuclear Information System (INIS)

    The effects of isotopically distinct organic carbon sources in sediments and CO2 enrichment on the stable carbon isotope composition of Thalassia testudinum (turtle grass) seedlings were investigated. Seedling leaves became increasingly 13C depleted in all treatments with time. In the CO2 enriched treatment, δ13C values for seedlings declined from -9.1 to -57.1 per mille over the nine month culture period; the latter value is the lightest stable carbon isotope composition ever reported for a higher plant. In all non-CO2-enriched treatments, δ13C values declined from -9.1 per mille at T=0 to between -18.3 and -22.2 per mille after nine months. The lack of treatment effect in the non-CO2-enriched cultures was probably due to the release and exchange of isotopically light CO2 from the CO2 enriched treatment within the relatively closed environment of the culture room. This exchange was reflected in media dissolved inorganic carbon (DIC) δ13C values that indicated increasing 13C depletion relative to the initial compositions of the synthetic seawater salts. Depletion of 13C in leaf tissue of seedlings in the non-CO2-enriched treatments occurred faster than did media DIC 13C depletion, suggesting an increase in isotopic fractionation as seedlings grew. The reasons for this increasing fractionation are unclear, but they may reflect a decreasing contribution of isotopically heavy seed research and/or increasing availability of exogenous carbon. 18 refs, 1 fig., 2 tabs

  3. [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

  4. Seasonal Variation in Stable Carbon and Nitrogen Isotope Values of Bats Reflect Environmental Baselines

    OpenAIRE

    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 varia-tion in consumers may a...

  5. 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

  6. 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

    2016-01-01

    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 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. PMID:27151563

  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

    2016-05-01

    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.

  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

    2016-01-01

    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. PMID:27151563

  9. 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

  10. Progress and challenges in using stable isotopes to trace plant carbon and water relations across scales

    Directory of Open Access Journals (Sweden)

    C. Werner

    2012-08-01

    Full Text Available Stable isotope analysis is a powerful tool for assessing plant carbon and water relations and their impact on biogeochemical processes at different scales. Our process-based understanding of stable isotope signals, as well as technological developments, has progressed significantly, opening new frontiers in ecological and interdisciplinary research. This has promoted the broad utilisation of carbon, oxygen and hydrogen isotope applications to gain insight into plant carbon and water cycling and their interaction with the atmosphere and pedosphere. Here, we highlight specific areas of recent progress and new research challenges in plant carbon and water relations, using selected examples covering scales from the leaf to the regional scale. Further, we discuss strengths and limitations of recent technological developments and approaches and highlight new opportunities arising from unprecedented temporal and spatial resolution of stable isotope measurements.

  11. 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.

  12. Depletion of 13C in lignin and its implications for stable carbon isotope studies

    International Nuclear Information System (INIS)

    Stable carbon isotope compositions of organic matter are now widely used to trace carbon flow in ecosystems, and have been instrumental in shaping current perceptions of the importance of terrestrial vegetation to estuarine and coastal marine environments. A general assumption in these and other studies relying on carbon isotope compositions for source identification of organic matter has been that the major biochemical components of plant tissues are isotopically invariant. We report here large differences between the carbon isotope compositions of the polysaccharide and lignin components of a variety of vascular plants, including the salt-marsh grass Spartina alterniflora, and demonstrate that the carbon isotope composition of Spartina detritus gradually changes during biogeochemical processing as polysaccharides are preferentially removed, leaving a material that is relatively enriched in lignin-derived carbon and depleted in 13C. (author)

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

    International Nuclear Information System (INIS)

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

  16. The carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica

    International Nuclear Information System (INIS)

    Highlights: ► δ13C-DIC reported from McMurdo Dry Valleys, Antarctica, streams. ► Stream water δ13CPDB values range −9.4‰ to +5.1‰, largely inorganic in character. ► Atmospheric exchange is the dominant control on δ13C-DIC. - Abstract: The McMurdo Dry Valleys region of Antarctica is the largest ice-free region on the continent. This study reports the first C stable isotope measurements for dissolved inorganic C present in ephemeral streams in four dry valleys that flow for four to twelve weeks during the austral summer. One of these valleys, Taylor Valley, has been the focus of the McMurdo Dry Valleys Long-Term Ecological Research (MCM-LTER) program since 1993. Within Taylor Valley, numerous ephemeral streams deliver water to three perennially ice-covered, closed-basin lakes: Lake Fryxell, Lake Hoare, and Lake Bonney. The Onyx River in the Wright Valley, the longest river in Antarctica, flows for 40 km from the Wright Lower Glacier and Lake Brownworth at the foot of the glacier to Lake Vanda. Streamflow in the McMurdo Dry Valley streams is produced primarily from glacial melt, as there is no overland flow. However, hyporheic zone exchange can be a major hydrogeochemical process in these streams. Depending on landscape position, these streams vary in gradient, channel substrate, biomass abundance, and hyporheic zone extent. This study sampled streams from Taylor, Wright, Garwood, and Miers Valleys and conducted diurnal sampling of two streams of different character in Taylor Valley. In addition, transect sampling was undertaken of the Onyx River in Wright Valley. The δ13CPDB values from these streams span a range of greater than 14‰, from −9.4‰ to +5.1‰, with the majority of samples falling between −3‰ and +2‰, suggesting that the C stable isotope composition of dissolved C in McMurdo Dry Valley streams is largely inorganic in character. Because there are no vascular plants on this landscape and no groundwater input to these streams

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

    OpenAIRE

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

    1990-01-01

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

  18. 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.)

  19. 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

  20. Stable carbon isotope fractionation by methanogens growing on different Mars regolith analogs

    Science.gov (United States)

    Sinha, Navita; Kral, Timothy A.

    2015-07-01

    In order to characterize stable carbon (13C/12C) isotope fractionation of metabolically produced methane by methanogens in martian settings, Methanothermobacter wolfeii, Methanosarcina barkeri, and Methanobacterium formicicum were cultured on four different Mars regolith analogs - JSC Mars-1, Artificial Mars Simulant, montmorillonite, and Mojave Mars Simulant - and also in their growth supporting media. These chemoautotrophic methanogens utilize CO2 for their carbon source and H2 for their energy source. When compared to the carbon isotope signature of methane when grown on their respective growth media, M. wolfeii and M. barkeri demonstrated variability in carbon isotope fractionation values during methanogenesis on the Mars analogs, while M. formicicum showed subtle or negligible difference in carbon isotope fractionation values. Interestingly, M. wolfeii and M. barkeri have shown relatively consistent enriched values of 12C on montmorillonite, a kind of clay found on Mars, compared to other Mars regolith analogs. In general, M. barkeri showed large carbon isotope fractionation compared to M. wolfeii and M. formicicum during methanognesis on various kinds of analogs. Stable carbon isotope fractionation is one of the techniques used to infer different origins, environments, and pathways of methanogensis. The results obtained in this novel research can provide clues to determine ambiguous sources of methane on Mars.

  1. 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

  2. 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

  3. Carbon allocation in plants and ecosystems - insights from stable isotope studies

    Science.gov (United States)

    Gessler, Arthur

    2014-05-01

    Trees are large global stores of carbon (C) that will be impacted by increased carbon dioxide levels and climate change. However, at present we cannot properly predict the carbon balance of forests in future as we lack knowledge on how plant physiological processes, the transfer of carbon within the plant, carbon storage, and remobilization in the plant tissues as well as the release of carbon from the roots to the soil interact with environmental drivers and ecosystem-scale processes. This paper will summarise how stable isotope techniques can give new insights in the fate of newly assimilated C in plants and ecosystems on time scales from hours to seasons and it will include studies either characterizing temporal and spatial variation in the natural abundance of carbon and oxygen isotopes or applying isotopically enriched tracers. It comprises the assessment of the mechanisms of C partitioning among specific metabolic pathways, between plant organs and into various ecosystem C pools with different residence times. Moreover stable isotopes are highly suitable tools to characterise the role of the phloem, which is the central long-distance conveyer distributing C from source to sinks and thus plays a central role in linking sites and structures of storage, growth and other metabolic activities. A deeper understanding of these processes and their interaction with environmental drivers is critical for predicting how trees and ecosystems will respond to coming global environmental changes, including increased temperature, altered precipitation, and elevated carbon dioxide concentrations.

  4. 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

  5. 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.; Michelsen, Anders; Schmidt, Niels Martin

    2011-01-01

    The use of stable isotopes in diet analysis usually relies on the different photosynthetic pathways of C3 and C4 plants, and the resulting difference in carbon isotope signature. In the Arctic, however, plant species are exclusively C3, and carbon isotopes alone are therefore not suitable 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...... distinct. As a result, our examination mainly relied on stable nitrogen isotopes. The interpretation of stable isotopes from faeces was difficult because of the large uncertainty in diet–faeces fractionation, whereas isotope signatures from wool suggested that the muskox summer diet consists of around 80...

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

    Science.gov (United States)

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

    2008-12-01

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

  7. Linking carbon and water cycles using stable isotopes across scales: progress and challenges

    Directory of Open Access Journals (Sweden)

    C. Werner

    2011-03-01

    Full Text Available Stable isotope analysis is a powerful tool for tracing biogeochemical processes in the carbon and water cycles. One particularly powerful approach is to employ multiple isotopes where the simultaneous assessment of the D/H,18O/16O and/or 13C/12C in different compounds provide a unique means to investigate the coupling of water and carbon fluxes at various temporal and spatial scales. Here, we present a research update on recent advances in our process-based understanding of the utilization of carbon, oxygen and hydrogen isotopes to lend insight into carbon and water cycling. We highlight recent technological developments and approaches, their strengths and methodological precautions with examples covering scales from minutes to centuries and from the leaf to the globe.

  8. 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...

  9. 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...

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

    Science.gov (United States)

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

    2012-12-01

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

  11. 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)

  12. 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...

  13. 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

  14. 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.

  15. 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.

  16. Source identification of polycyclic aromatic hydrocarbons in fine atmospheric particulates using stable carbon isotopic analysis

    International Nuclear Information System (INIS)

    In this paper, a method is established to quantitatively partition fractional contributions of polycyclic aromatic hydrocarbons (PAHs) in fine atmospheric particulate matters by using stable carbon isotopic analysis. Dichloromethane extraction, TLC purification, and gas chromatography-combustion system and isotope mass spectrometry (GC/C/IRMS), are used to measure the stable carbon isotope compositions (δ13C). The fractional contributions of coal combustion, vehicle exhaust and biomass burning to the PAHs in the fine particulate matters (PM2.5) collected in Jiading district, a suburb of Shanghai, are estimated. The results show that the δ13C values increase with decreasing molecular weight. The coal combustion and biomass burning play bigger role than vehicle exhaust in the PAHs, compared to the δ13C values of PAHs in all kinds of potential pollution sources. The estimated contributions from coal combustion,vehicle exhaust and biomass burning to PAHs of PM2.5 range from 3%- 21%, 29%- 33% and 46%- 67%, respectively, which agree well with the surrounding condition of the sampling site, indicating that it is feasible to estimate the fractional contributions of PAHs quantitatively by using stable carbon isotopic analysis. (authors)

  17. Examining the Role of Multiple Carbon Sources in Isoprene Synthesis in Plants Using Stable Isotope Techniques

    Science.gov (United States)

    Funk, J. L.; Mak, J. E.; Lerdau, M. T.

    2001-12-01

    The carbon source for phytogenc isoprene is an issue with important ramifications for both atmospheric and biological science because of its impact on the isotopic signature of isoprene and its oxidation products and because it lends insight into the function that isoprene serves within leaves. Although recently assimilated carbon is believed to be the primary carbon source for isoprene production in plants, variation in diurnal and seasonal isoprene fluxes that cannot be explained by temperature, light, and leaf development have led to the suggestion that alternative carbon sources may contribute. Stable isotopes of carbon can be used to identify changes in carbon partitioning into isoprene synthesis, and mixing models can assess the relative importance of each source. In preliminary studies, we document an additional 8-10 \\permil discrimination in isoprene emitted in the absence of photosynthesis. This change in signature suggests that the carbon source is switched from recently obtained photosynthate to a source more depleted in 13C. We propose that intermediates from carbohydrate degradation and/or re-fixation of CO2 from mitichondrial respiration and photorespiration can contribute to isoprene production. In addition, we expect alternative carbon sources to be most important when photosynthate is limiting (e.g. during water stress events). Photosynthesis, respiration, and isoprene emission measurements are used to calculate the isotopic signatures of the three potential carbon pools: photosynthate derived from ambient CO2, photosynthate derived from respired CO2, and carbohydrate-derived intermediates.

  18. 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

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

    International Nuclear Information System (INIS)

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

  20. 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

  1. 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) ...

  2. 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...

  3. Stable carbon isotope reconstruction of ungulate diet changes through the seasonal cycle

    OpenAIRE

    Codron, D.; Lee-Thorp, J A; M. Sponheimer; J. Codron

    2007-01-01

    We analysed stable carbon isotope ratios (13C) in faeces of 11 African ungulate species from three South African savanna environments to determine whether this approach is sufficiently sensitive to record short-term seasonal diet changes in browsers (BR), mixed-feeders (IM), and grazers (GR). At monthly intervals, faecal 13C revealed variations in proportions of C3 (browse) to C4 (grass) biomass consumed that were not detected by broader dry versus wet season comparisons, including subtle die...

  4. Carbon and nitrogen stable isotopes in fast food: Signatures of corn and confinement

    OpenAIRE

    Jahren, A. Hope; Kraft, Rebecca A.

    2008-01-01

    Americans spend >100 billion dollars on restaurant fast food each year; fast food meals comprise a disproportionate amount of both meat and calories within the U.S. diet. We used carbon and nitrogen stable isotopes to infer the source of feed to meat animals, the source of fat within fries, and the extent of fertilization and confinement inherent to production. We sampled food from McDonald's, Burger King, and Wendy's chains, purchasing >480 servings of hamburgers, chicken sandwiches and frie...

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

    Science.gov (United States)

    Shen, Xiaoli; Xu, Zemin; Zhang, Xichang; Yang, Fangxing

    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 2mg/kg lambda-cyhalothrin and 84 and 154 days in non-sterile and sterile soils spiked with 10mg/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 2mg/kg lambda-cyhalothrin, and to -27.5‰ with 10mg/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. PMID:26092290

  6. Stable isotopes of carbon and nitrogen in the study of organochlorine contaminants in albatrosses and petrels

    International Nuclear Information System (INIS)

    Highlights: • δ13C, δ15N and OCs were analyzed in tissues of five Procellariiformes species. • High intraspecific variability was found in SI values as well as in OCs levels. • OCs and SI exhibited different patterns among species. • δ13C and δ15N reflected mainly the foraging habitats in non-breeding season. - Abstract: Carbon and nitrogen stable isotopes in albatrosses and petrels collected off southern Brazil were compared with concentrations of organochlorine contaminants (OCs). δ13C and δ15N values, as well as OCs concentrations, exhibited a high degree of variability among individuals and overlap among species. δ13C values reflected latitudinal differences among species, with lower values found in Wandering and Tristan Albatrosses and higher values found in Black-browed and Atlantic Yellow-nosed Albatrosses and White-chinned Petrels. Some relationships were found between OCs and stable isotopes, but in general a partial ‘uncoupling’ was observed between OCs concentrations and stable isotopes ratios (especially for δ15N). δ13C and δ15N values in Procellariiformes tissues during the non-breeding season appear to be a better indicator of foraging habitats than of trophic relationships, which may partially explain the high degree of variability between concentrations of OCs and stable isotopes ratios in birds with a diversified diet and wide foraging range

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    M. Saccon

    2013-05-01

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

  9. Investigating Pathways of Nutrient and Energy Flows Through Aquatic Food Webs Using Stable Isotopes of Carbon and Nitrogen

    International Nuclear Information System (INIS)

    Carbon and nitrogen stable isotopes can provide valuable insights into pathways of nutrient and energy flows in aquatic ecosystems. Carbon stable isotopes are principally used to trace pathways of organic matter transfer through aquatic food webs, particularly with regard to identifying the dominant sources of nutrition for aquatic biota. Stable isotopes of carbon have been widely used to answer one of the most pressing questions in aquatic food web ecology - to what degree do in-stream (autochthonous) and riparian (allochthonous) sources of energy fuel riverine food webs? In conjunction with carbon stable isotopes, nitrogen stable isotopes have been used to determine the trophic position of consumers and to identify the number of trophic levels in aquatic food webs. More recently, stable nitrogen isotopes have been recommended as indicators of anthropogenic disturbances. Specifically, agricultural land uses and/or sewage effluent discharge have been shown to significantly increase δ15N signatures in primary producers and higher order consumers in freshwater, estuarine and marine environments. Together, carbon and nitrogen stable isotopes can be used to examine natural food web functions as well as the degree to which human modifications to catchments and aquatic environments can influence aquatic ecosystem function. (author)

  10. 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

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

    International Nuclear Information System (INIS)

    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‰

  12. 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‰.

  13. 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.

  14. 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.

  15. 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

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

    Science.gov (United States)

    Rhee, Jaehyon; Pilachowski, C. A.

    2013-01-01

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

  17. 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...

  18. 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.

  19. Stable isotope applications

    International Nuclear Information System (INIS)

    The following domains of stable isotope applications are presented: - isotope dilution analyses as in trace analyses or volume and mass determinations; - stable isotopes as tracers as applied in environmental studies, agricultural research, products and objects authentification, transport phenomena, reaction mechanisms, determinations of structure and complex biological function, metabolism studies, diagnostic respiration tests, positron emission tomography; - equilibrium isotopic effects as investigated in measurements of effects, studies of equilibrium conditions, the mechanism of drug action, study of natural processes, water circuit, temperature measurements; - kinetic isotopic effects, as, for instance, reaction rates and mechanisms, solvent isotopic effects; - stable isotopes for advanced nuclear reactors as, for instance, uranium nitride with 15 N as nuclear fuel or 157 Gd for reactivity control. In spite of the difficulties regarding stable isotope use and first of all, of the difficult and costly analytical techniques, a continuous growth of the number of stable isotope applications in different fields is registered. The number of works and scientific meetings on the subject, as organized by the International Society of Isotopes and IAEA-Vienna, Gordon Conferences, regional meetings in Germany, France, etc. increase continuously. Development of the stable isotope application on a larger scale requires improving both their production technologies as well as those of labelled substances and, at the same time, the analytical methods

  20. Effects of acid mine drainage on dissolved inorganic carbon and stable carbon isotopes in receiving streams

    International Nuclear Information System (INIS)

    Dissolved inorganic carbon (DIC) constitutes a significant fraction of a stream's carbon budget, yet the role of acid mine drainage (AMD) in DIC dynamics in receiving streams remains poorly understood. The objective of this study was to evaluate spatial and temporal effects of AMD and its chemical evolution on DIC and stable isotope ratio of DIC (δ13CDIC) in receiving streams. We examined spatial and seasonal variations in physical and chemical parameters, DIC, and δ13CDIC in a stream receiving AMD. In addition, we mixed different proportions of AMD and tap water in a laboratory experiment to investigate AMD dilution and variable bicarbonate concentrations to simulate downstream and seasonal hydrologic conditions in the stream. Field and laboratory samples showed variable pH, overall decreases in Fe2+, alkalinity, and DIC, and variable increase in δ13CDIC. We attribute the decrease in alkalinity, DIC loss, and enrichment of 13C of DIC in stream water to protons produced from oxidation of Fe2+ followed by Fe3+ hydrolysis and precipitation of Fe(OH)3(s). The extent of DIC decrease and 13C enrichment of DIC was related to the amount of HCO3- dehydrated by protons. The laboratory experiment showed that lower 13C enrichment occurred in unmixed AMD (2.7 per mille ) when the amount of protons produced was in excess of HCO3- or in tap water (3.2 per mille ) where no protons were produced from Fe3+ hydrolysis for HCO3- dehydration. The 13C enrichment increased and was highest for AMD-tap water mixture (8.0 per mille ) where Fe2+ was proportional to HCO3- concentration. Thus, the variable downstream and seasonal 13C enrichment in stream water was due in part to: (1) variations in the volume of stream water initially mixed with AMD and (2) to HCO3- input from groundwater and seepage in the downstream direction. Protons produced during the chemical evolution of AMD caused seasonal losses of 50 to >98% of stream water DIC. This loss of DIC in AMD impacted streams may have

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

    Directory of Open Access Journals (Sweden)

    M. Saurer

    2008-11-01

    Full Text Available Carbon monoxide in the atmosphere is originating from various combustion and oxidation processes. Recently, the proportion of CO resulting from the combustion of wood for domestic heating may have increased due to political measures promoting this renewable energy source. Here, we used the stable isotope composition of CO (δ13C and δ18O for the characterization of different CO sources in Switzerland, along with other indicators for traffic and wood combustion (NOx-concentration, aerosol light absorption at different wavelengths. We assessed diurnal variations of the isotopic composition of CO at 3 sites during winter: a village site dominated by domestic heating, a site close to a motorway and a rural site. The isotope ratios of wood combustion emissions were studied at a test facility, indicating significantly lower δ18O of CO from wood combustion compared to traffic emissions. At the village and the motorway site, we observed very pronounced diurnal δ18O-variations of CO with an amplitude of up to 8‰. Solving the isotope mass balance equation for three distinct sources (wood combustion, traffic, clean background air resulted in diurnal patterns consistent with other indicators for wood burning and traffic. The average night-time contribution of wood-burning to total CO was 70% at the village site, 47% at the motorway site and 28% at the rural site based on the isotope mass balance. As this analysis showed a strong sensitivity towards the pure source isotope values, we additionally applied a combined CO/NOx-isotope model for verification. Here, we separated the CO emissions into different sources based on different CO/NOx emissions ratios for wood combustion and traffic, and inserted this information in the isotope mass balance equation. Accordingly, a highly significant agreement between measured and calculated δ18O-values of CO was found (r=0

  2. Carbon and nitrogen biogeochemistry in the ocean: A study using stable isotope natural abundance

    Science.gov (United States)

    Rau, G. H.; Desmarais, David J.

    1985-01-01

    Determining the biogeochemical pathways traveled by carbon and nitrogen in the ocean is fundamental to the understanding of how the ocean participates in the cycling of these elements within the biosphere. Because biological production, metabolism, and respiration can significantly alter the natural abundance of C-13 and N-15, these abundances can provide important information about the nature of these biological processes and their variability in the marine environment. The research initially seeks to characterize the spatial and temporal patterns of stable isotope abundances in organic matter, and to relate these abundances to C and N biogeochemical processes within selected areas of the northeastern Pacific Ocean.

  3. Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system

    Science.gov (United States)

    Geeraert, N.; Omengo, F. O.; Govers, G.; Bouillon, S.

    2016-01-01

    A significant amount of carbon is transported to the ocean as dissolved organic carbon (DOC) in rivers. During transport, it can be transformed through microbial consumption and photochemical oxidation. In dark incubation experiments with water from the Tana River, Kenya, we examined the consumption of DOC through microbial decomposition and the associated change in its carbon stable isotope composition (δ13C). In 15 of the 18 incubations, DOC concentrations decreased significantly by 10 to 60 %, with most of the decomposition taking place within the first 24-48 h. After 8 days, the remaining DOC was up to 3 ‰ more depleted in 13C compared with the initial pool, and the change in δ13C correlated strongly with the fraction of DOC remaining. We hypothesize that the shift in δ13C is consistent with greater microbial lability of DOC originating from herbaceous C4 vegetation than DOC derived from woody C3 vegetation in the semi-arid lower Tana. The results complement earlier findings that the stable isotope concentration of riverine DOC does not necessarily reflect the proportion of C3 and C4-derived DOC in the catchment: besides spatial distribution patterns of different vegetation types, processing within the river can further influence the δ13C of riverine OC.

  4. 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

  5. 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.

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

    International Nuclear Information System (INIS)

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

  7. 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

  8. 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.

  9. Carbon and nitrogen stable isotopes in coastal benthic populations under multiple organic enrichment sources

    International Nuclear Information System (INIS)

    In a dispersive coastal area under multiple organic enrichment sources, stable isotopes were used to trace organic sources of carbon and nitrogen in sediments and benthic macrofauna. The Bivalve Abra alba and the Polychaetes Nephtys sp. and Pectinaria (Lagis) koreni were reliable indicators of the input of terrestrial-derived organic matter into this coastal area, either originated in outfall sewage discharges or estuarine outflow. An isotopic depletion was observed up to 250 m from the outfall branches, much stronger in the biota than in the sediments. An enrichment of 2 per mille in the sediments, and 2-6 per mille in the species was noticed in sites located farther than 1500 m from the outfall. Depositivores and carnivores/omnivores gave the best picture of the extension of the sewage dispersion and incorporation into the food web.

  10. 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...

  11. Uses of stable isotopes

    International Nuclear Information System (INIS)

    The most important fields of stable isotope use with examples are presented. In isotope dilution analysis the stable isotopes are used in trace analysis, measurements of volumes and masses. In the field of stable isotope use as tracers the following applications are encountered: transport phenomena, environmental studies, agricultural research, authentication of products and objects, archaeometry, studies of reaction mechanisms, structure and function determination of complex biological entities, studies of metabolism, breath test for diagnostic. In the domain of isotope equilibrium effects applications in the study of mechanism of drug action, study of natural processes, investigation of equilibrium conditions and water cycle as well as in temperature measurements are encountered. Stable isotopes are also used in advanced nuclear reactors, particularly, the uranium nitride with 15 N as nuclear fuel and 157 Gd for reactor control. In spite of some difficulties of stable isotope use, especially related to analytical techniques, which are slow and expensive, the number of papers reporting this subject is steadily growing as well the number of scientific meetings organized by International Isotope Society and IAEA, Gordon Conferences, and regional meetings in Germany, France, etc. Stable isotope application development on large scale is ensured by improving their production technologies, as well as by development of new labelled compounds and of analytical techniques. (author)

  12. 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.

  13. Stable isotope laser spectroscopy

    Science.gov (United States)

    Becker, J. F.; Yaldaei, Ramil; Mckay, Christopher P.

    1989-01-01

    Recent advances in semiconductor laser technology have produced a reliable lightweight device ideally suited for a spacecraft high resolution molecular spectrometer. Lead-salt tunable diode lasers (TDL) emit in several spectral modes, each with a very narrow linewidth of -0.0003/cm. This spectral resolution is much narrower than typical Doppler broadened molecular linewidths in the mid-IR range. Thus it is possible to detect individual rotational lines within the vibrational band and measure their intensity, which can be used to determine gas concentration. The narrow spectral lines of any impurity gas tend to lie between the narrow lines of the gas of interest. This represents a major advantage over the accepted gas chromatograph mass spectrometer (GCMS) technique for measuring gas concentrations and isotope ratios. The careful and extensive gas purification procedures required to remove impurities for reliable GCMS measurements will not be required for an IR laser gas analysis. The infrared laser gas analysis technique is being developed to measure stable isotopic ratios of gases such as CO2, CH4, N2O, and NH3. This will eventually lead to development of instruments capable of in situ istopic measurements on planets such as Mars. The carbon (C-12, C-13) isotope ratio is indicative of the type of carbon fixation mechanisms (e.g., photosynthesis, respiration) in operation on a planet, while the nitrogen (N-14, N-15) isotope ratio can probably be used to date nitrogen-bearing Martian samples. The absorbance ratio of two adjacent lines of CO2 in the 2300/cm (4.3 micron) region of the spectrum was measured. The precision of the measurement is presently better than 1 percent and significant improvement is anticipated as rapid sweep-integration techniques and computer controlled data acquistion capabilities are incorporated.

  14. 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.

  15. 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.

  16. Synthetic approaches to carbohydrates enriched with stable isotopes of carbon, hydrogen and oxygen

    International Nuclear Information System (INIS)

    This paper reports on the extent to which stable isotopically-enriched compounds have found application in chemistry and biochemistry that has paralleled the development of analytical methods for isotopic discrimination. Current renewed interest in stable isotopes reflects recent technical advances in mass spectrometry, nuclear magnetic resonance spectroscopy, and rapid-reaction technology. These advances have been so significant that the limiting factor in studies where stable isotopes can be used to advantage is often the availability of the appropriate labeled compounds. Several key considerations guide the choice of a synthetic route to a particular labeled compound. Because labeled precursors are expensive, yields must be high for all reactions subsequent to the introduction of the isotope. To optimize isotopic yield, the isotope should be introduced as near as possible to the end of the synthetic route. If possible, syntheses should utilize available enriched precursors, and reactions should be simple and reliable

  17. 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

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

    International Nuclear Information System (INIS)

    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 (δ13CDIC) comes from two sources: decomposition of organic matter and carbonate dissolution within the aquifer sediments, whereas in the leachate-contaminated groundwater, DIC concentrations and δ13CDIC 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 CO2 (P CO2) was generally above the atmospheric, hence atmospheric CO2 as a source of carbon in DIC pool was negligible in the aquifer. P CO2 values in the aquifer in

  19. 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

  20. 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

    Stable carbon and oxygen isotope composition of pedogenic carbonates were studied from the Quaternary loess-paleosol sequence of Sutto in Hungary to investigate genetic processes in a paleoenvironmental context and to distinguish subtypes. Bulk carbonate samples taken at 2 cm vertical resolution,...... matter 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....

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Influence of environmental factors on dissolved nitrate stable isotopes under denitrifying conditions - carbon sources and water isotopes

    Science.gov (United States)

    Wunderlich, A.; Meckenstock, R.; Einsiedl, F.

    2012-04-01

    Stable isotopes in dissolved nitrate are regularly used to identify sources of nitrate contamination in aquifers and water bodies. A dual isotope plot of 15N and 18O in nitrate can provide good evidence of the origin of such pollution as various sources have different isotopic signatures. Microbial denitrification changes both isotopic values by removing nitrate with lighter isotopes first, thereby increasing δ18O as well as δ15N. This change can distort the determination of sources but also has the potential to be used to identify and quantify microbial denitrification. Previous studies found a wide range of enrichment factors (ɛ) that did not allow conclusions towards the extent of microbial denitrification. However, it was found that during denitrification at each respective field site or laboratory experiment, there was a constant ratio in increase of the values of δ18O in relation to δ15N. That ratio was, however, not constant across field sites and the values published range from below 0.5 to more than 1.0. The reasons for these variations in enrichment factors and relative enrichment of oxygen compared to nitrogen are yet unknown. We conducted microcosm experiments with three different bacterial species to elucidate possible influences of environmental factors on these parameters. As a result we conclude that the type of carbon source available to denitrifying bacteria can play a role in the value of the enrichment factors, but not in the relative enrichment of the two isotopes. Specifically we found that complex hydrocarbons (toluene, benzoate) produce significantly different enrichment factors in nitrate than a simple hydrocarbon substrate (acetate). The relative enrichment of δ18O compared to δ15N was 0.86. We hypothesise that this influence is based on a variation in process kinetics of cross-membrane nitrate transport in relation to intracellular nitrate reduction. The core of the hypothesis is that nitrate transport into the cell becomes rate

  6. 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.

  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. 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).

  9. The link between assimilation and below-ground processes - stable isotopes as tools to assess carbon transfer

    Science.gov (United States)

    Gessler, A.; Wingate, L.; Ogeé, J.; Offermann, C.; Kodama, N.

    2011-12-01

    At present, there is lack of knowledge on how plant physiological processes, the transfer of carbon within the plant, carbon storage and remobilization in the plant tissues as well as the release of carbon from the roots to the soil interact with ecosystem-scale processes. On the background of global climate change, we need to mechanistically link plant physiology, CO2 net exchange between ecosystems and the atmosphere and plant biomass accumulation. This is the basis for predicting productivity of forests as well as their carbon sequestration potential in future. This paper will give an overview on how stable isotope studies can give insights into the fate of newly assimilated carbon transported within trees and transferred to the soil and atmosphere. The paper includes assessments characterizing temporal and spatial variation in the natural abundance of carbon and oxygen isotopes or applying isotopically enriched tracers. In addition, it highlights the fact that the stable isotope composition of assimilates transported within the plant contains important time integrated information on environmental conditions, leaf physiology, and post-photosynthetic metabolism. The paper on the one hand focuses on the fast turn over carbon pools, which fuel plant respiration and soil microbial activity and on the other hand explores the transfer of the isotope information to long-lived compounds in plant archives such as tree rings.

  10. Estimation of the contribution of soil carbon to paddy rice and soil to rice carbon transfer factor using natural abundances of stable carbon isotopes

    International Nuclear Information System (INIS)

    To obtain the soil-to-rice transfer factor (TF) of carbon-14 (14C), TF of stable carbon was estimated by measuring stable carbon isotope ratios (13C/12C) and total C concentrations in rice grain and associated soil samples collected throughout Japan. Carbon isotope ratios were reported in terms of a δ13C value. By comparing δ13C values for brown rice, white rice and bran, we concluded that white rice was the most suitable part to be used for this estimation because it reflects products from photosynthesis. The δ13C values for white rice and soil showed a weak correlation which may indicate a potential carbon supply from soil to rice. Thus we took a statistical approach to estimate the percent of soil-origin carbon in rice plants. We found that a maximum 1.6% of total carbon in rice plants was from soil under the reasonable assumptions that the carbon fractionation by paddy rice was -19 per mille and δ13C of atmospheric CO2 was -8 per mille. Maximum TF value ranged from 0.05 to 0.5 for stable carbon and the value would also be applicable for 14C because the carbon fractionation effect for 14C would be negligible in carbon transfer. (author)

  11. Stable hydrogen and carbon isotopic compositions of biogenic methanes from several shallow aquatic environments

    International Nuclear Information System (INIS)

    Stable hydrogen (δD) and carbon (δ/sup 13/C) isotopic compositions of methane gas bubbles formed in the sediments of several shallow aquatic environments were measured and found to range from -3460/oo to -2630/oo and from -75.00/oo to -51.50/oo, respectively. Evaluation of the δD data with a previously published model implies that acetate dissimilation accounts for about 50% to 80% of the total methane production. δD-CH/sub 4/ and δ/sup 13/C-CH/sub 4/ are generally inversely correlated; this indicates that the observed isotopic variation is not solely due to differential methane oxidation. δ/sup 13/C-CH/sub 4/ values reported in this paper imply that methane produced in these sediments is generally substantially more /sup 13/C-depleted than the estimated average atmospheric methane source. Methane with a δD near the estimated atmospheric source average is produced in some of these sediments; this apparent agreement may be fortuitous as few relevant data are available

  12. 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.

  13. 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.

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

    Science.gov (United States)

    Zhu, R.; Lin, Y.-S.; Lipp, J. S.; Meador, T. B.; Hinrichs, K.-U.

    2014-09-01

    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. Compound-specific stable carbon isotopic analysis of amino sugars obtained from marine sediment extracts indicated that glucosamine and galactosamine were mainly derived from organic detritus, whereas muramic acid showed isotopic imprints from indigenous bacterial activities. The δ13C analysis of amino sugars provides a valuable addition to the biomarker-based characterization of microbial metabolism in the deep marine biosphere, which so far has been lipid oriented and biased towards the detection of archaeal signals.

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

    International Nuclear Information System (INIS)

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

  16. 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.

  17. Fractional absorption of active absorbable algal calcium (AAACa) and calcium carbonate measured by a dual stable-isotope method

    Science.gov (United States)

    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 ...

  18. 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 ...

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

    Science.gov (United States)

    Ambrose, Stanley H.; DeNiro, Michael J.

    1989-05-01

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

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

    International Nuclear Information System (INIS)

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

  1. 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.

  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. Analytical system for stable carbon isotope measurements of low molecular weight (C2-C6 hydrocarbons

    Directory of Open Access Journals (Sweden)

    T. Röckmann

    2011-06-01

    Full Text Available We present setup, testing and initial results from a new automated system for stable carbon isotope ratio measurements on C2 to C6 atmospheric hydrocarbons. The inlet system allows analysis of trace gases from air samples ranging from a few liters for urban samples and samples with high mixing ratios, to many tens of liters for samples from remote unpolluted regions with very low mixing ratios. The centerpiece of the sample preparation is the separation trap, which is used to separate CO2 and methane from the compounds of interest. The main features of the system are (i the capability to sample up to 300 l of air, (ii long term (since May 2009 operational δ13C accuracy levels in the range 0.3–0.8 ‰ (1-σ, and (iii detection limits of order 1.5–2.5 ngC (collected amount of substance for all reported compounds. The first application of this system was the analysis of 21 ambient air samples taken during 48 h in August 2009 in Utrecht, the Netherlands. Results obtained are generally in good agreement with those from similar urban ambient air studies. Short sample intervals allowed by the design of the instrument help to illustrate the complex diurnal behavior of hydrocarbons in an urban environment, where diverse sources, dynamical processes, and chemical reactions are present.

  4. Carbon and Nitrogen Stable Isotopes in Fastfood: Signatures of Corn and Confinement

    Science.gov (United States)

    Jahren, H.; Kraft, R.

    2008-12-01

    Americans spend more than one hundred billion dollars on restaurant fastfood each year; fastfood meals comprise a disproportionate amount of both meat and calories within the U.S. diet. Frustrated by futile attempts to gain information about the origin and production of fastfood from the companies themselves, we used carbon and nitrogen stable isotopes to infer the source of feed to meat animals, the source of fat within fries, and the extent of fertilization and confinement inherent to production. We sampled food from McDonald's, Burger King and Wendy's chains, purchasing more than 480 servings of hamburgers, chicken sandwiches and fries within geographically-distributed U.S. cities: Los Angeles, San Francisco, Denver, Detroit, Boston and Baltimore. From the entire sample set of beef and chicken, only 12 servings of beef had δ13C chicken, reflecting uniform confinement and exposure to heavily fertilized feed for all animals. The δ13C value of fries differed significantly among restaurants indicating that the chains employed different protocols for deep- frying: Wendy's clearly employed only corn oil, while McDonald's and Burger King favored other vegetable oils; this differed from ingredient reports. Our results highlighted the overwhelming importance of corn agriculture within virtually every aspect of fastfood manufacture.

  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. 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

  7. 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…

  8. 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

  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. Normalization of stable isotope data for carbonate minerals: Implementation of IUPAC guidelines

    Science.gov (United States)

    Kim, Sang-Tae; Coplen, Tyler B.; Horita, Juske

    2015-06-01

    Carbonate minerals provide a rich source of geochemical information because their δ13C and δ18O values provide information about surface and subsurface Earth processes. However, a significant problem is that the same δ18O value is not reported for the identical carbonate sample when analyzed in different isotope laboratories in spite of the fact that the International Union of Pure and Applied Chemistry (IUPAC) has provided reporting guidelines for two decades. This issue arises because (1) the δ18O measurements are performed on CO2 evolved by reaction of carbonates with phosphoric acid, (2) the acid-liberated CO2 is isotopically fractionated (enriched in 18O) because it contains only two-thirds of the oxygen from the solid carbonate, (3) this oxygen isotopic fractionation factor is a function of mineralogy, temperature, concentration of the phosphoric acid, and δ18O value of water in the phosphoric acid, (4) researchers may use any one of an assortment of oxygen isotopic fractionation factors that have been published for various minerals at various reaction temperatures, and (5) it sometimes is not clear how one should calculate δ18OVPDB values on a scale normalized such that the δ18O value of SLAP reference water is -55.5 ‰ relative to VSMOW reference water. To enable researchers worldwide to publish the same δ18O value (within experimental uncertainty) for the same carbonate sample, we have re-evaluated reported acid fractionation factors for calcite at 25, 50, and 75 °C and propose a revised relation for the temperature dependence of oxygen isotopic acid fractionation factor, αCO2(ACID)-calcite , of where T is temperature in kelvin. At 25 °C, αCO2(ACID)-calcite = 1.01025 , the most commonly accepted value for this quantity. We propose a normalization protocol in which (1) the internationally distributed carbonate isotopic reference materials NBS 18 and NBS 19 are interspersed among carbonate samples analyzed by treatment with phosphoric acid, (2

  11. 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.

  12. 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.

  13. 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

  14. 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.

  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. The stable carbon isotope composition of PM 2.5 and PM 10 in Mexico City Metropolitan Area air

    Science.gov (United States)

    López-Veneroni, D.

    The sources and distribution of carbon in ambient suspended particles (PM 2.5 and PM 10) of Mexico City Metropolitan Area (MCMA) air were traced using stable carbon isotopes ( 13C/ 12C). Tested potential sources included rural and agricultural soils, gasoline and diesel, liquefied-petroleum gas, volcanic ash, and street dust. The complete combustion of LP gas, diesel and gasoline yielded the lightest δ13C values (-27 to -29‰ vs. PDB), while street dust (PM 10) represented the isotopically heaviest endmember (-17‰). The δ13C values of rural soils from four geographically separated sites were similar (-20.7 ± 1.5‰). δ13C values of particles and soot from diesel and gasoline vehicle emissions and agricultural soils varied between -23 and -26‰. Ambient PM samples collected in November of 2000, and March and December of 2001 at three representative receptor sites of industrial, commercial and residential activities had a δ13C value centered around -25.1‰ in both fractions, resulting from common carbon sources. The predominant carbon sources to MCMA atmospheric particles were hydrocarbon combustion (diesel and/or gasoline) and particles of geological origin. The significantly depleted δ13C values from the industrial site reflect the input of diesel combustion by mobile and point source emissions. Based on stable carbon isotope mass balance, the carbon contribution of geological sources at the commercial and residential sites was approximately 73% for the PM 10 fraction and 54% for PM 2.5. Although not measured in this study, biomass-burning emissions from nearby forests are an important carbon source characterized by isotopically lighter values (-29‰), and can become a significant contributor (67%) of particulate carbon to MCMA air under the prevalence of southwesterly winds. Alternative sources of these 13C-depleted particles, such as cooking fires and municipal waste incineration, need to be assessed. Results show that stable carbon isotope

  18. Relationship between climate and vegetation and the stable carbon isotope chemistry of soils in the eastern Mojave Desert, Nevada

    International Nuclear Information System (INIS)

    The relationship between the stable C-isotope composition of the soil environment and modern climate and vegetation was determined empirically along a present-day climatic transect in the eastern Mojave Desert. The δ13C of the soil CO2 and carbonates decreased with increasing elevation and plant density, even though plant assemblages at all elevations were isotopically similar. Several factors, including differences in the ratios of pedogenic of limestone calcite and differences in past vegetation, were considered as explanations of this trend, However, it appears that in the sparsely vegetated Mojave Desert, the δ13C of pedogenic carbonate is controlled by differences in plant density and biological activity. This relationship may provide a tool for assessing past vegetational densities, as long as the vegetation is isotopically homogeneous. (author)

  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. 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.

  1. 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...

  2. 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

  3. [Hydrochemistry and Dissolved Inorganic Carbon Stable Isotope of Shibing Dolomite Karst Area in Guizhou Province].

    Science.gov (United States)

    Xiao, Shi-zhen; Lan, Jia-cheng; Yuan, Dao-xian; Wang, Yun; Yang, Long; Ao, Xiang-hong

    2015-06-01

    Totally 49 water samples were collected in Shibing Dolomite Karst World Natural Heritage Site in Guizhou Province to analyze the characteristics and controlling factors of both the surface and underground waters, as well as the features and their origins of the dissolved inorganic carbon isotope. It was found that the pH of the study area was neutral to alkaline with low concentrations of total dissolved solids. The cations were dominated by Ca2+, Mg2 and anions by HCO3-, featured by HCO3-Ca x Mg type water. The ratios of Cl-, NO3- and SO4(2-) in the allogenic water from the shale area in the northern catchment were higher than those in autogenic water from the dolomite karst area, so did the concentration of Si. The SIc and SId of the allogenic waters in the shale area were negative. After the waters entered into and flew by the dolomite karst area, both the SIc and SId increased to over 0. It could be told by the water chemistry that the hydrochemistry was little impacted by the rainfall and human activities. The Gibbs plot revealed that the chemical composition of the waters was mainly controlled by rock weathering. The δ(13)C(DIC) of the surface waters ranged from -8.27% to -11.55% per hundred, averaging -9.45% per hundredo, while that of the underground waters ranged from -10.57% per hundred to -15.59% per hundred, averaging -12.04% per hundred, which was lighter than that of surface water. For the distribution features, it was found the δ(13)C(DIC), of the upper reaches of branches of Shangmuhe River was lighter than that of the lower reach, while that of the main river Shangmuhe River was relatively complex. Based on the mass balance of stable isotopes and the δ(13)C(DIC), the ratio of the origin of DIC of the ground water was calculated. It was found that 51.2% was from soil CO2, and 48.8% was from the rock itself. PMID:26387311

  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. 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

  6. 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

  7. 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.

  8. 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.

  9. Palaeo-equatorial temperatures and carbon-cycle evolution at the Triassic- Jurassic boundary: A stable isotope perspective from shallow-water carbonates from the UAE

    Science.gov (United States)

    Honig, M. R.; John, C. M.

    2013-12-01

    The Triassic-Jurassic boundary was marked by global changes including carbon-cycle perturbations and the opening of the Atlantic Ocean. These changes were accompanied by one of the major extinction events of the Phanerozoic. The carbon-cycle perturbations have been recorded in carbon isotope curves from bulk carbonates, organic carbon and fossil wood in several Tethyan locations and have been used for chemostratigraphic purposes. Here we present data from shallow-marine carbonates deposited on a homoclinal Middle Eastern carbonate ramp (United Arab Emirates). Our site was located at the equator throughout the Late Triassic and the Early Jurassic, and this study provides the first constraints of environmental changes at the low-latitudes for the Triassic-Jurassic boundary. Shallow-marine carbonate depositional systems are extremely sensitive to palaeoenvironmental changes and their usefulness for chemostratigraphy is being debated. However, the palaeogeographic location of the studied carbonate ramp gives us a unique insight into a tropical carbonate factory at a time of severe global change. Stable isotope measurements (carbon and oxygen) are being carried out on micrite, ooids and shell material along the Triassic-Jurassic boundary. The stable isotope results on micrite show a prominent negative shift in carbon isotope values of approximately 2 ‰ just below the inferred position of the Triassic-Jurassic boundary. A similar isotopic trend is also observed across the Tethys but with a range of amplitudes (from ~2 ‰ to ~4 ‰). These results seem to indicate that the neritic carbonates from our studied section can be used for chemostratigraphic purposes, and the amplitudes of the carbon isotope shifts provide critical constraints on the magnitude of carbon-cycle perturbations at low latitudes across the Triassic-Jurassic boundary. Seawater temperatures across the Triassic-Jurassic boundary will be constrained using the clumped isotope palaeo-thermometer applied

  10. 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...

  11. 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.

  12. 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

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

    Science.gov (United States)

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

    1999-08-01

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

  14. 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

  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. 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...

  17. Mercury stable isotope biogeochemistry

    International Nuclear Information System (INIS)

    Full text: Methods for high precision measurement of natural Hg isotope ratios by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) have been developed recently by our group and allow the use of Hg isotopes to trace the biogeochemistry of Hg. Mercury has seven stable isotopes ranging from 196 to 204 amu.We have found that the isotopic composition of Hg varies by both mass dependent fractionation (MDF) and mass independent fractionation (MIF). Even and odd isotopes of Hg are fractionated by mass-dependent processes, whereas odd isotopes are also fractionated in a mass-independent way by photochemical reactions. Isotope ratios are measured relative to the NIST 3133 Hg standard reference material. MDF is reported as δ202Hg (± 0.08 %o, 2 SD) which is the difference in 202Hg/198Hg between a sample and NIST 3133 in permil (%o). MIF is reported as Δ 201Hg (± 0.05 %o, 2 SD), which is the difference in 201Hg/198Hg ratio in permil from what the 201Hg/198Hg ratio would be if the fractionation were entirely mass dependent. In this presentation we summarize the range of Hg isotopic compositions of a variety of environmental and geological materials. In previous work we described biotic and abiotic laboratory fractionation experiments demonstrating the range of mass dependent and mass independent fractionation caused by mercury redox transformations in the surface environment. Thus far we have found that MIF occurs during photochemical reduction of methyl-Hg and Hg2+ following a Rayleigh-like fractionation. Bacterial reduction causes Rayleigh-like MDF but no MIF. Coastal-marine and freshwater fish from North America have positive Δ 201Hg values (0.2 to > 3 %o) reflecting transfer of methyl-Hg into the food web after partial reduction by photochemical reactions. Most coals and the organic horizons of soils from North America have negative Δ 201Hg values (-0.1 to -0.4 %o), possibly reflecting the influence of Hg that was photochemically reduced in

  18. Continuous measurements of stable carbon isotopes in CO2 with a near-IR laser absorption spectrometer

    Science.gov (United States)

    Tanaka, Kotaro; Kojima, Ryota; Takahashi, Kenshi; Tonokura, Kenichi

    2013-09-01

    A near-IR laser absorption spectrometer using a technique of wavelength modulation spectroscopy is used to measure stable carbon isotope ratios of ambient CO2 (δ13C) via the absorption lines 12CO2 R(17) (2ν1 + ν12 - ν12 + ν3) at 4978.205 cm-1 and 13CO2 P(16) (ν1 + 2ν2 + ν3) at 4978.023 cm-1. The isotope ratios are measured with a reproducibility of 0.02‰ (1σ) in a 130-s integration time over a 12-h period. The humidity effect on δ13C values has been evaluated in laboratory experiments. The δ13C values of CO2 in ambient air were measured continuously over 8 days and agreed well with those from isotope ratio mass spectrometry of canister samples. The spectrometer is thus capable of real-time, in situ measurements of stable carbon isotope ratios of CO2 under ambient conditions.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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)

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

    OpenAIRE

    Van Geldern, R; M. Nowak; Zimmer, M.; Szizybalski, A.; Myrttinen, A.; Barth, J.; Jost, H.

    2014-01-01

    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 (δ13C) of injected CO2 was significantly different from background values. In order to observe the breakthrough of the isotope tracer continuously, the new instruments were...

  5. 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.

  6. Coastal sediments under the influence of multiple organic enrichment sources: An evaluation using carbon and nitrogen stable isotopes

    International Nuclear Information System (INIS)

    Sediment descriptors (grain size, total volatile solids, redox potential) and stable carbon and nitrogen isotopes were used to trace the origin of organic matter in a coastal area under multiple organic enrichment sources (urban outfall and a major estuary). The sediments fines content and total volatile solids were similar to outfall pre-operation period (1994), but the incorporation of terrestrial organic matter within the sediments located closer to the outfall was diagnosed by depleted 13C values (-24.2 ± 0.38 per mille ) and 15N values (2.4 ± 0.93 per mille ). Data also indicated depleted nitrogen signature at larger distances from the outfall than the carbon signature, due to confounding sediment grain size properties. Analysis in the bivalve Abra alba gave the same results for both isotopes and thus allowed a coherent interpretation of the spatial extent of the organic enrichment, highlighting the importance of bringing a biological element into the environmental assessment.

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

    Science.gov (United States)

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

    2014-04-01

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

  8. 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

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

    International Nuclear Information System (INIS)

    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 (δ15N) 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 (δ13C) 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

  10. 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

  11. 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 - http://dx.doi.org/10.5285/22235f1a-b7f3-687f-e053-6c86abc0c8a6" target="_blank">doi:10.5285/22235f1a-b7f3-687f-e053-6c86abc0c8a6.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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)

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

    International Nuclear Information System (INIS)

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

  18. 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.

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

    Science.gov (United States)

    Jesus, Fabiene Maria; Pereira, Marcelo Ribeiro; Rosa, Cassiano Sousa; Moreira, Marcelo Zacharias; Sperber, Carlos Frankl

    2015-01-01

    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. PMID:26390400

  20. Stable isotope analysis in the ivory

    International Nuclear Information System (INIS)

    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 (δ 13C) and nitrogen (δ 15N) 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)

  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. 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.

  3. 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

  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. 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

  6. 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

  7. 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.

  8. Evolution of the stable carbon isotope composition of atmospheric CO2 over the last glacial cycle

    Science.gov (United States)

    Eggleston, S.; Schmitt, J.; Bereiter, B.; Schneider, R.; Fischer, H.

    2016-03-01

    We present new δ13C measurements of atmospheric CO2 covering the last glacial/interglacial cycle, complementing previous records covering Terminations I and II. Most prominent in the new record is a significant depletion in δ13C(atm) of 0.5‰ occurring during marine isotope stage (MIS) 4, followed by an enrichment of the same magnitude at the beginning of MIS 3. Such a significant excursion in the record is otherwise only observed at glacial terminations, suggesting that similar processes were at play, such as changing sea surface temperatures, changes in marine biological export in the Southern Ocean (SO) due to variations in aeolian iron fluxes, changes in the Atlantic meridional overturning circulation, upwelling of deep water in the SO, and long-term trends in terrestrial carbon storage. Based on previous modeling studies, we propose constraints on some of these processes during specific time intervals. The decrease in δ13C(atm) at the end of MIS 4 starting approximately 64 kyr B.P. was accompanied by increasing [CO2]. This period is also marked by a decrease in aeolian iron flux to the SO, followed by an increase in SO upwelling during Heinrich event 6, indicating that it is likely that a large amount of δ13C-depleted carbon was transferred to the deep oceans previously, i.e., at the onset of MIS 4. Apart from the upwelling event at the end of MIS 4 (and potentially smaller events during Heinrich events in MIS 3), upwelling of deep water in the SO remained reduced until the last glacial termination, whereupon a second pulse of isotopically light carbon was released into the atmosphere.

  9. 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

  10. Stable isotope tracing of trout hatchery carbon to sediments and foodwebs of limestone spring creeks

    International Nuclear Information System (INIS)

    Limestone springs support productive ecosystems and fisheries, yet aquaculture may modify or impair these ecosystems. We determined trout hatchery organic contribution to spring creek sediments and foodwebs with natural abundance stable isotope methods. Hatchery feed, waste, and trout were significantly enriched in δ13C relative to autotrophs and wild fish. Spring creek sediments were enriched in δ13C toward the hatchery endmember relative to reference streams without hatcheries and relative to a larger larger-order, spring-influenced stream. Contribution of hatchery C to spring creek sediments was greatest during March and associated with greatest sediment %C. Contribution of hatchery C to pollution-tolerant isopod diet was 39-51% in a stream receiving limestone spring water via hatchery effluent. Isopods of one spring creek also relied on hatchery-derived C within one month of hatchery closure. Four years later, less pollution pollution-tolerant amphipods dominated and consumed non-vascular over vascular autotrophs (86%). Isopods of a second spring creek with an active hatchery did not appear to be using hatchery matter directly, but were enriched in δ34S relative to a spring creek tributary with no hatchery influence. Isopods in both of these streams were relatively enriched in δ15N, indicating general nutrient enrichment from surrounding agricultural land use. The contribution of hatchery vs. wild fish in diet of herons and egrets was traced with δ13C of guano. These birds were strongly dependent on stocked trout in a spring creek with a recently closed state trout hatchery, and also near another large, state-run hatchery. Heron dependence on hatchery fish in the spring creek decreased with time since hatchery closure. Use of stable isotope natural abundance techniques in karst spring creeks can reveal stream impairment due to aquaculture, specific C sources to bio-indicating consumers, losses of farmed fish to predation, and potential exposure of higher

  11. 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.

  12. Characterization of bottled waters with stable isotopes of hydrogen, oxygen and carbon

    International Nuclear Information System (INIS)

    In recent years bottled waters became popular beverages and important part of the human diet. They are a food product that considerably depends on the environment from which it originates, not only at the place where it is produced, but predominantly on the conditions in the recharge area of the wells captured for bottling. These waters originate from various parts of the hydrological cycle and their natural origin is reflected in their isotopic composition. In stable isotope analyses of bottled waters two investigative approaches can be used; that from hydrology and the other from food analyses. In this study 58 domestic and foreign brands and 16 replicates of bottled waters, randomly collected on the Slovene market in 2004, were analysed for δ2H and δ18O and δ13CDIC. This investigation helped (1) to determine and test the classification of bottled waters, (2) to determine the natural sources of bottled water and (3) to discern between the natural and production processes. (author)

  13. 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.

  14. CO2 uptake of a mature Acacia mangium plantation estimated from sap flow measurements and stable carbon isotope discrimination

    Directory of Open Access Journals (Sweden)

    H. Wang

    2013-07-01

    Full Text Available Canopy CO2 uptake (FCO2 of a subtropical mature extit{A. mangium} plantation was estimated by combining sap flow measurements and stable carbon isotope discrimination (Δ in Southern China from 2004 to 2007. The mechanistic relationship linking FCO2, Δ in leaf sap, and sap flow based canopy stomatal conductance (Gs was applied in our study. No significant seasonal variations were observed in Δ or in the ratio of the intercellular and ambient CO2 concentrations (Ci/Ca, although diurnal Ci/Ca varied between sunlit and shaded leaves. A sensitivity analysis showed that estimates of FCO2 were more sensitive to dynamics in Gs than in Ca and Δ. By using seasonally and canopy averaged Ci/Ca values, an acceptable estimate of FCO2 was obtained. FCO2 exhibited similar diurnal variation to that of Gs. Large seasonal variation in FCO2 was attributed to the responsiveness of Gs to vapour pressure deficit, photosynthetically active radiation, and soil moisture deficit. Our estimate of FCO2 for a mature A. mangium plantation (2.13 ± 0.40 g C m−2 day−1 approached the lower range of values for subtropical mixed forest, probably due to lower mean canopy stomatal conductance, higher Ci/Ca, and greater tree height than other measured forests. Our estimate was also lower than values determined by satellite-based modeling or component carbon analysis, suggesting the necessity of stand level flux data for verification. Qualitatively, the sap flux/stable isotope results compared well with gas exchange results. Differences in results between the two approaches reflected variability due to leaf position and age, which could be reduced for sap flux/stable isotope, which uses canopy average values of Gs and Ci/Ca.

  15. 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.

  16. 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

  17. 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.

  18. 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.; S. Parra; Rozada, F.; Valencia-Vila, J.; Viana, I. G.

    2014-01-01

    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 mai...

  19. 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.

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

    International Nuclear Information System (INIS)

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

  1. Seasonal variation of Fatty acids and stable carbon isotopes in sponges as indicators for nutrition: biomarkers in sponges identified.

    Science.gov (United States)

    Koopmans, Marieke; van Rijswijk, Pieter; Boschker, Henricus T S; Marco, Houtekamer; Martens, Dirk; Wijffels, Rene H

    2015-02-01

    To get a better understanding of sponge feeding biology and efficiencies, the fatty acid (FA) composition and (13)C natural abundance of sponges and of suspended particulate matter (SPM) from surrounding seawater was studied in different seasons at three locations. Haliclona oculata and Haliclona xena from the Oosterschelde, the Netherlands, Halichondria panicea and H. xena from Lake Veere, the Netherlands, and Aplysina aerophoba and Dysidea avara from the Mediterranean, Spain, were studied. Several FA biomarkers for different algal groups, bacteria and sponge biomass were identified in all sponges. The FA concentration variation in sponges was related to changes in fatty acid concentration in SPM. Stable carbon isotopic ratios (δ(13)C) in sponge specific FAs showed very limited seasonal variation at all sites. Algal FAs in sponges were mainly acquired from the SPM through active filtration in all seasons. At the two sites in the Netherlands only in May (spring), the sponge specific FAs had similar δ(13)C ratios as algal FAs, suggesting that sponges were mainly growing during spring and probably summer. During autumn and winter, they were still actively filtering, but the food collected during this period had little effect on sponge δ(13)C values suggesting limited incorporation of filtered material into the sponge body. The sponge A. aerophoba relied mostly on the symbiotic bacteria. In conclusion, fatty acid composition in combination with stable carbon isotope analysis can be used to analyze the food source of sponges. PMID:25107690

  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. Comment: critical examination of stable isotope analysis as a means for tracing carbon pathways in stream ecosystems

    International Nuclear Information System (INIS)

    Stable isotope analysis (SIA) is studied as a technique for deciphering food webs and identifying impacts of alterations in land use. The 13C values for allochthonous litter, attached algae and consumers in stream ecosystems were discussed as using stable isotope analysis. 17 refs

  5. Consistent Methodologies for Determining, Relating and Disseminating Light Stable Isotopic Measurement Results: The Carbon Dioxide Example

    Science.gov (United States)

    Klinedinst, D. B.; Verkouteren, R. M.

    2001-05-01

    In conjunction with the International Atomic Energy Agency (IAEA), the Atmospheric Chemistry Group (ACG) of National Institute of Standards and Technology (NIST) has coordinated an international CO2 isotope ratio mass spectrometry (IRMS) intercomparison exercise. The results of this exercise, specifically designed to overcome inherent deficiencies revealed by previous intercomparisons, achieved a 2 to 3 fold reduction (improvement) in the reproducibility of reported results across laboratories. Concurrently, the ACG developed and deployed an interactive Web-based data processing interface [http://www.nist.gov/widps-co2]. The interface has open architecture and a transparent, downloadable source code. This data processing system leverages the results of the intercomparison exercise and provides a consistent means by which raw CO2 measurement results are related to the internationally accepted Vienna Pee Dee Belemnite (VPDB) scale. Prominent features of the CO2 intercomparison exercise included: mandatory chemical and operational procedures, reporting of discretionary factors, direct determination of the cross contamination effect within the ion source, the reporting of raw measurement results and centralized data processing. The data reduction interface uses IAEA defined standard procedures for stable isotope measurements and data processing. It incorporates currently defined reference values for selected IAEA and NIST CO2 Reference Materials (RMs). On a routine basis, users can also determine and use assigned values for secondary laboratory standards as input. One or two point (i.e., normalized) realization of the VPDB scale is provided as are optional inputs for the oxygen isotope fractionation factor(α ). We attribute the success of the CO2 intercomparison exercise primarily to the centralized data processing using raw measurements rather than customary result-based data. The centralized processing, in essence, eliminates inconsistencies between integrated

  6. Stable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake

    Science.gov (United States)

    Wharton, R. A. Jr; Lyons, W. B.; Des Marais, D. J.; Wharton RA, J. r. (Principal Investigator)

    1993-01-01

    Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is an amictic, oligotrophic, 34-m-deep, closed-basin lake in Taylor Valley, Antarctica. Its perennial ice cover minimizes wind-generated currents and reduces light penetration, as well as restricts sediment deposition into the lake and the exchange of atmospheric gases between the water column and the atmosphere. The biological community of Lake Hoare consists solely of microorganisms -- both planktonic populations and benthic microbial mats. Lake Hoare is one of several perennially ice-covered lakes in the McMurdo Dry Valleys that represent the end-member conditions of cold desert and saline lakes. The dry valley lakes provide a unique opportunity to examine lacustrine processes that operate at all latitudes, but under an extreme set of environmental conditions. The dry valley lakes may also offer a valuable record of catchment and global changes in the past and present. Furthermore, these lakes are modern-day equivalents of periglacial lakes that are likely to have been common during periods of glacial maxima at temperate latitudes. We have analyzed the dissolved inorganic carbon (DIC) of Lake Hoare for delta 13C and the organic matter of the sediments and sediment-trap material for delta 13C and delta 15N. The delta 13C of the DIC indicates that 12C is differentially removed in the shallow, oxic portions of the lake via photosynthesis. In the anoxic portions of the lake (27-34 m) a net addition of 12C to the DIC pool occurs via organic matter decomposition. The dissolution of CaCO3 at depth also contributes to the DIC pool. Except near the Canada Glacier where a substantial amount of allochthonous organic matter enters the lake, the organic carbon being deposited on the lake bottom at different sites is isotopically similar, suggesting an autochthonous source for the organic carbon. Preliminary inorganic carbon flux calculations suggest that a high percentage of the organic carbon fixed in the water column is

  7. Metal Stable Isotopes in Paleoceanography

    Science.gov (United States)

    Anbar, Ariel D.; Rouxel, Olivier

    2007-05-01

    Considered esoteric only a few years ago, research into the stable isotope geochemistry of transition metals is moving into the geoscience mainstream. Although initial attention focused on the potential use of some of these nontraditional isotope systems as biosignatures, they are now emerging as powerful paleoceanographic proxies. In particular, the Fe and Mo isotope systems are providing information about changes in oxygenation and metal cycling in ancient oceans. Zn, Cu, Tl, and a number of other metals and metalloids also show promise. Here we review the basis of stable isotope fractionation as it applies to these elements, analytical considerations, and the current status and future prospects of this rapidly developing research area.

  8. Determining Carbon and Oxygen Stable Isotope Systematics in Brines at Elevated p/T Conditions to Enhance Monitoring of CO2 Induced Processes in Carbon Storage Reservoirs

    Science.gov (United States)

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

    2012-12-01

    Stable carbon isotope ratios (δ13C) are a powerful tool for inferring carbon sources and mixing ratios of injected and baseline CO2 in storage reservoirs. Furthermore, CO2 releasing and consuming processes can be deduced if the isotopic compositions of end-members are known. At low CO2 pressures (pCO2), oxygen isotope ratios (δ18O) of CO2 usually assume the δ18O of the water plus a temperature-dependent isotope fractionation factor. However, at very high CO2 pressures as they occur in CO2 storage reservoirs, the δ18O of the injected CO2 may in fact change the δ18O of the reservoir brine. Hence, changing δ18O of brine constitutes an additional tracer for reservoir-internal carbon dynamics and allows the determination of the amount of free phase CO2 present in the reservoir (Johnson et al. 2011). Further systematic research to quantify carbon and oxygen isotope fractionation between the involved inorganic carbon species (CO2, H2CO3, HCO3-, CO32-, carbonate minerals) and kinetic and equilibrium isotope effects during gas-water-rock interactions is necessary because p/T conditions and salinities in CO2 storage reservoirs may exceed the boundary conditions of typical environmental isotope applications, thereby limiting the accuracy of stable isotope monitoring approaches in deep saline formations (Becker et al. 2011). In doing so, it is crucial to compare isotopic patterns observed in laboratory experiments with artificial brines to similar experiments with original fluids from representative field sites to account for reactions of dissolved inorganic carbon (DIC) with minor brine components. In the CO2ISO-LABEL project, funded by the German Ministry for Education and Research, multiple series of laboratory experiments are conducted to determine the influence of pressure, temperature and brine composition on the δ13C of DIC and the δ18O of brines in water-CO2-rock reactions with special focus placed on kinetics and stable oxygen and carbon isotope fractionation

  9. CO2 uptake of a mature Acacia mangium plantation estimated from sap flow measurements and stable carbon isotope discrimination

    Science.gov (United States)

    Wang, H.; Zhao, P.; Zou, L. L.; McCarthy, H. R.; Zeng, X. P.; Ni, G. Y.; Rao, X. Q.

    2014-03-01

    A simple, nondestructive method for the estimation of canopy CO2 uptake is important for understanding the CO2 exchange between forest and atmosphere. Canopy CO2 uptake (FCO2) of a subtropical mature A. mangium plantation was estimated by combining sap flow measurements and stable carbon isotope discrimination (Δ) in Southern China from 2004 to 2007. The mechanistic relationship linking FCO2, Δ in leaf sap, and sap flow-based canopy stomatal conductance (Gs) was applied in our study. No significant seasonal variations were observed in Δ or in the ratio of the intercellular and ambient CO2 concentrations (Ci/Ca), although diurnal Ci/Ca varied between sunlit and shaded leaves. A sensitivity analysis showed that estimates of FCO2 were more sensitive to dynamics in Gs than in Ca and Δ. By using seasonally and canopy averaged Ci/Ca values, we obtained an acceptable estimate of FCO2 compared to other estimates. FCO2 exhibited similar diurnal variation to that of Gs. Large seasonal variation in FCO2 was attributed to the responsiveness of Gs to vapor pressure deficit, photosynthetically active radiation, and soil moisture deficit. Our estimate of FCO2 for a mature A. mangium plantation (2.13 ± 0.40 gC m-2 d-1) approached the lower range of values for subtropical mixed forests, probably due to lower mean canopy stomatal conductance, higher Ci/Ca, and greater tree height than other measured forests. Our estimate was also lower than values determined by satellite-based modeling or carbon allocation studies, suggesting the necessity of stand level flux data for verification. Qualitatively, the sap flux/stable isotope results compared well with gas exchange results. Differences in results between the two approaches likely reflected variability due to leaf position and age, which should be reduced for the combined sap flux and isotope technique, as it uses canopy average values of Gs and Ci/Ca.

  10. 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

  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. 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

  13. Environmental controls on the stable carbon isotopic composition of soil organic carbon: implications for modelling the distribution of C3 and C4 plants, Australia

    OpenAIRE

    Wynn, Jonathan G.; Michael I. Bird

    2011-01-01

    We use multivariate statistics to examine the continental-scale patterns of the stable carbon isotopic composition (δ13C) of soil organic carbon (SOC) from a data set collected throughout the natural range of variation in climatic, edaphic and biotic controls in Australia. Climate and soil texture (percent of mineral particles <63 μm) are found to be the dominant controls on δ13CSOC. Of the environmental variables analysed, the strongest correlations to δ13CSOC do not simply occur with res...

  14. 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

  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. 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)

  17. 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)

  18. Stable carbon and nitrogen isotopes and amino acids in Holocene sediments of Lake Lonar, central India

    Science.gov (United States)

    Menzel, Philip; Gaye, Birgit; Wiesner, Martin; Basavaiah, Nathani; Prasad, Sushma; Stebich, Martina; Anoop, Ambili; Riedel, Nils

    2013-04-01

    Investigations on surface sediments and a sediment core from Lake Lonar in central India were carried out within the framework of the HIMPAC (Himalaya: Modern and Past Climate) programme. The aim was to understand recent productivity, sedimentation, and degradation processes and to reconstruct variations in Holocene lake conditions on the basis of biogeochemical analysis on a 10 m long sediment core retrieved from the centre of Lake Lonar. Located in India's core monsoon zone, Lake Lonar offers valuable information about the climate development of the whole region. The lake is situated at the floor of a meteorite impact structure on the Deccan plateau basalt. The modern lake is characterised by brackish water, high alkalinity, severe eutrophication, and bottom water anoxia. The lake is about 6 m deep and fed by rainfall during the SW monsoon season and three perennial streams. Since no out-flowing stream is present and no seepage loss occurs, the lake level is highly sensitive to the balance of precipitation and evaporation. Here we present C/N, carbon and nitrogen isotope, and amino acid data of bulk organic matter from modern lake and Holocene core sediments. Modern conditions are mainly related to human activity which started to have persistent influence on the biological and chemical lake properties at ~1200 cal a BP. The distribution of δ13C in the modern sediments is driven by the ratio between terrestrial and aquatic organic matter, while δ15N seems to be influenced by redox conditions at the sediment-water-interface with elevated values at shallow oxic stations. Differences in the amino acid assemblages of oxic and anoxic surface sediment samples were used to calculate an Ox/Anox ratio indicating the redox conditions during organic matter degradation. The onset of the monsoon reconstructed from the sediment core occurred at ca. 11450 cal a BP. The early Holocene core sediments are characterised by low sedimentation rate, low aquatic productivity, and

  19. 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.

  20. 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

  1. Dissolved inorganic carbon evolution and stable carbon isotope fractionation in acid mine drainage contaminated streams: Insights from a laboratory study

    International Nuclear Information System (INIS)

    Samples of groundwater, spring water and stream water contaminated by acid mine drainage (AMD), and uncontaminated stream water were collected and allowed to evolve in contact with air in the laboratory for 15-88 days. The objective of this study was to (1) document temporal changes in dissolved inorganic C (DIC) concentrations and stable isotopic composition (δ13CDIC) and (2) to determine the reaction mechanism and resulting isotopic fractionation (13C/12C) accompanying the chemical evolution of AMD. The contaminated spring and stream samples and one groundwater sample (with no HCO3-) showed temporal decreases in pH, Fe2+, alkalinity, and DIC, and enrichment in δ13CDIC. One contaminated groundwater sample (with HCO3- between 529 and 630 mg/L) showed a temporal increase in pH despite observed decreases in Fe2+, alkalinity and DIC, and enrichment in δ13CDIC. The uncontaminated stream samples showed a continuous temporal increase in pH, relatively constant alkalinity and DIC, and enrichment in δ13CDIC. The results suggest that proton production related to Fe2+ transformation is the driving force for DIC loss in AMD-contaminated samples, and that DIC loss can be described by first order kinetics. The C isotope enrichment rates associated with DIC loss in the contaminated samples varied between 1.0 per mille and 1.8 per mille for stream water, 2.1 per mille and 2.6 per mille for the spring, 1.0 per mille and 1.2 per mille for groundwater with no HCO3-, and 7.6 per mille and 9.3 per mille for groundwater with high HCO3-. Variations in 13C enrichment in the contaminated samples are attributed to differences in the initial Fe2+:HCO3- ratio. The effect of proton production on 13C enrichment in the AMD-contaminated samples was modeled as a Rayleigh-type distillation, whereby isotope fractionation was constant and occurred in an 'equilibrium closed system'. In the uncontaminated stream samples, C exchange between DIC and atmospheric CO2 resulted in an overall enrichment

  2. Carbon and nitrogen stable isotopes reveal the use of pelagic resources by the invasive Ponto-Caspian mysid Limnomysis benedeni.

    Science.gov (United States)

    Fink, Patrick; Harrod, Chris

    2013-01-01

    The Ponto-Caspian mysid shrimp Limnomysis benedeni has rapidly invaded freshwater systems throughout Europe and is now found in extremely high abundances in invaded systems. However, very little is known about the trophic ecology of this mysid in invaded ecosystems, in particular the relative degree of herbivory, carnivory and detritivory of this potentially omnivorous species and where it derives its energy, i.e. via carbon fixed by algae inhabiting benthic or pelagic habitats or through allochthonous inputs. Here, we investigate the trophic ecology of L. benedeni in a recently established population in North-Western Germany using stable carbon and nitrogen isotopes. Our results suggest that in contrast to its previous classifications as a benthic or bentho-pelagic herbivore, L. benedeni is an omnivorous species, which can derive the bulk of its carbon from pelagic resources. Its trophic niche in different invaded ecosystems will be determined by multiple, system-dependent factors which have to be considered in order to predict the mysids' invasion potential. PMID:24117428

  3. 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. PMID:26296731

  4. Origin of particulate organic carbon in the marine atmosphere as indicated by it stable carbon isotopic composition

    International Nuclear Information System (INIS)

    Organic carbon concentration and isotopic composition were determined in samples of atmospheric particulate matter collected in 1979 at remote marine locations (Enewetak atoll, Sargasso Sea) during the SEAREX (Sea-Air Exchange) program field experiments. Atmospheric Particulate Organic Carbon (POC) concentrations were found to be in the range of 0.3 to 1.2 mg. m-3, in agreement with previous literature data. The major mass of POC was found on the smallest particles (r13C/12C of the small particles is close to the one expected (d13C = 26 +- 20//sub infinity/) for atmospheric POC of continental origin. For all the samples analysed so far, it appears that more than 80% of atmospheric POC over remote marine areas is of continental origin. This can be explained either by long-range transport of small sized continental organic aserosols or by the production of POC in the marine atmosphere from a vapor phase organic carbon pool of continental origin. The POC in the large size fraction of marine aerosols (13C = -21 +- 20/00) for POC associated with sea-salt droplets transported to the marine atmosphere

  5. 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.

  6. Tracking Movement of Plant Carbon Through Soil to Water by Lignin Phenol Stable Carbon Isotope Composition in a Small Agricultural Watershed

    Science.gov (United States)

    Crooker, K.; Filley, T.; Six, J.; Frey, J.

    2005-12-01

    Few studies integrate land cover, soil physical structure, and aquatic physical fractions when investigating the fate of agricultural carbon in watersheds. In crop systems that involve rotations of soy (a C3 plant) and corn (a C4 plant) the large intrinsic differences in stable carbon isotope values and lignin plus cutin chemistry enable tracking of plant carbon movement from soil fractions to DOM and overland flow during precipitation events. In a small (~3Km2) agricultural basin in central Indiana, we studied plant carbon dynamics in a soy/corn agricultural rotation (2004-2005) to determine the relative inputs of these two plants to soil fractions and the resultant contributions to dissolved, colloidal, and particulate organic matter when mobilized. Using bulk isotope values the fraction of carbon derived from corn in macroaggregates (>250 micron), microaggregates (53-250 mm), and silts plus clays (compound specific isotope analysis of lignin in the soil fractions revealed a wide range of relative inputs among the monomers with cinnamyl phenols being almost exclusively (~ 93%) derived from corn. Syringyl phenols ranged from 75-56% corn and vanillyl phenols ranged from 37-40% corn carbon. The relative input among the fractions mirrors closely the comparative plant chemistry abundances between soy and corn. During export of DOM from the land to the stream the relative abundance of plant source varied with discharge (0.05-1.8 m3/sec) as increases in flow increased the relative export of corn-derived C from the fields. Over the full range of flows lignin phenols varied from 0.05 to 82% corn-derived with the greatest relative corn input for cinnamyl and syringyl carbon. The trend with stream discharge indicates a progressive movement of particulate corn residues with overland flow. Ongoing studies look to resolve contributions of algae, bacteria and terrestrial plants to soil fractions and their mobilized components.

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

    International Nuclear Information System (INIS)

    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 13C and 15N 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 13C and 15N 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)

  8. 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

  9. 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

  10. 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.

  11. Stable Isotope Group 1983 progress report

    International Nuclear Information System (INIS)

    The work of the Stable Isotope Group of the Institute of Nuclear Sciences in the fields of isotope geology, isotope hydrology, geochronology, isotope biology and related fields, and mass spectrometer instrumentation, during 1983, is described

  12. Stable Isotope Group 1982 progress report

    International Nuclear Information System (INIS)

    The work of the Stable Isotope Group of the Institute of Nuclear Sciences during 1982, in the fields of isotope geology, isotope hydrology, geochronology, isotope biology and mass spectrometer instrumentation, is described

  13. 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.

  14. Radioactive and stable isotope geology

    International Nuclear Information System (INIS)

    Aimed at post-graduate and post-doctoral researchers in geochemistry, this book reflects the rapid changes in the applications of radioactive and stable isotope analysis to a range of geological and geochemical problems. Isotropic chemistry and methods used in mass spectroscopy are discussed initially. The second section deals with radiometric dating methods. The role of isotopes in climate and environmental research is also explored. The book closes with a section on extra-terrestrial matter, geothermometry and the isotopic geochemistry of the Earth's lithosphere. (UK)

  15. Evaluating microbial carbon sources in Athabasca oil sands tailings ponds using natural abundance stable and radiocarbon isotopes

    Science.gov (United States)

    Ahad, J. M.; Pakdel, H.

    2013-12-01

    Natural abundance stable (δ13C) and radiocarbon (Δ14C) isotopes of phospholipid fatty acids (PLFAs) were used to evaluate the carbon sources utilized by the active microbial populations in surface sediments from Athabasca oil sands tailings ponds. The absence of algal-specific PLFAs at three of the four sites investigated, in conjunction with δ13C signatures for PLFAs that were generally within ~3‰ of that reported for oil sands bitumen (~ -30‰), indicated that the microbial communities growing on petroleum constituents were dominated by aerobic heterotrophs. The Δ14C values of PLFAs ranged from -906 to -586‰ and pointed to a significant uptake of fossil carbon (up to ~90% of microbial carbon derived from petroleum), particularly in PLFAs (e.g., cy17:0 and cy19:0) often associated with petroleum hydrocarbon degrading bacteria. The comparatively higher levels of 14C in other, less specific PLFAs (e.g., 16:0) indicated the preferential uptake of younger organic matter by the general microbial population (~50-80% of microbial carbon derived from petroleum). Since the main carbon pools in tailings sediment were essentially 'radiocarbon dead' (i.e., no detectable 14C), the principal source for this modern carbon is considered to be the Athabasca River, which provides the bulk of the water used in the bitumen extraction process. The preferential uptake of the minor amount of young and presumably more biodegradable material present in systems otherwise dominated by recalcitrant petroleum constituents has important implications for remediation strategies. On the one hand, it implies that mining-related organic contaminants could persist in the environment long after tailings pond reclamation has begun. Alternatively, it may be that the young, labile organic matter provided by the Athabasca River plays an important role in stimulating or supporting the microbial utilization of petroleum carbon in oil sands tailings ponds via co-metabolism or priming processes

  16. 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.

  17. Stable isotopes of nitrogen and carbon in an aquatic food web recently invaded by Dreissena polymorpha (Pallas)

    International Nuclear Information System (INIS)

    The carbon and nitrogen concentrations and the stable isotopic compositions (δ13C and δ15N) of major abiotic and biotic constituents were determined in Oneida Lake, New York. This lake was invaded by the zebra mussel (Dreissena polymorpha) in 1990 and there have been concomitant changes in various biotic and abiotic lake properties. The C (46-49%) and N (12%) concentrations and C:N ratios (3.9-4) of zebra mussel flesh were similar to those reported for other lakes. Trophic positions were reflected in the δ15N values for which walleye > gizzard shad and yellow perch > Daphnia spp. and zebra mussel flesh > seston and sediment. There was an average increase of 3.6%015N per trophic transfer. Results from the δ13C analysis suggest that Daphnia spp. were using a distinct source of organic carbon whereas zebra mussel were using the entire seston resource. Only yellow perch showed a significant shift in δ13C values (1.1%0), possibly reflecting a shift in a food source and diet from 1992 to 1993. (author). 48 refs., 2 tabs., 2 figs

  18. 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.

  19. Plant DNA: A new substrate for carbon stable isotope analysis and a potential paleoenvironmental indicator

    Science.gov (United States)

    Jahren, A. Hope; Petersen, Gitte; Seberg, Ole

    2004-03-01

    The δ13C value of fossil plant materials can be used to gain insight into the dominant photosynthetic pathway, as well as other environmental attributes, of ancient plant ecosystems. Nucleotide sequences from land plant nucleic acids extracted from 400 ka fossil sediments have been recognized as the oldest authenticated fossil deoxyribonucleic acid (DNA), making the inference of plant taxonomy possible in substrates devoid of plant macrofossils and microfossils. If the C isotope relationship between bulk plant tissue and associated plant nucleic acids were known, fossil plant nucleic acids could be analyzed for δ13C value and used as land plant isotopic substrates within mixed organic material. Toward this end, we present δ13C analyses of nucleic acids isolated from 12 higher plant species that span the full phylogenetic diversity of seed plants. Extracted nucleic acids were dominated by double-stranded DNA containing fragments of rbcL gene ˜350 base pairs in length. The C isotope compositions of plant nucleic acids were found to be enriched in 13C relative to bulk plant tissue by a constant value = 1.39‰. This study represents the first comparison of the δ13C value of nucleic acids to the δ13C value of bulk tissue for multicellular organisms; our results contrasted with the minimal fractionations reported for microorganisms. Because the isotopic enrichment is constant across tracheophytes, the δ13C value of fossil plant DNA can be used as a paleoenvironmental indicator, eliminating the need for morphological recognition of fossil plant material in paleoenvironmental studies.

  20. An updated estimation of the stable carbon and oxygen isotopic compositions of automobile CO emissions

    Science.gov (United States)

    Tsunogai, Urumu; Hachisu, Yosuke; Komatsu, Daisuke D.; Nakagawa, Fumiko; Gamo, Toshitaka; Akiyama, Ken-ichi

    We estimate up-to-date values of the average isotopic compositions of CO emitted from automobiles. In the estimation, we determined the isotopic compositions of CO in tail pipe exhaust for four gasoline automobiles and two diesel automobiles under varying conditions of both idling and running. While the dependence on the automobile manufacturer is little, each automobile equipped with functional catalytic converter exhibits a large temporal δ13C and δ18O variation. They tend to show 13C and 18O enrichment in accordance with the reduction of CO in exhaust, suggesting that the functional catalytic converter in engines enhances the δ13C and δ18O values of CO from tail pipes through a kinetic isotope effect during CO destruction. Assuming that automobiles run a modeled driving cycle, we estimated the average δ13C and δ18O of CO to be -23.8±0.8‰ PDB and +25.3±1.0‰ SMOW, respectively, for recent gasoline automobiles, and -19.5±0.7‰ PDB and +15.1±1.0‰ SMOW, respectively, for recent diesel automobiles. While the δ13C and δ18O values of recent gasoline automobiles coincide well with the isotopic compositions of source CO in present trunk road atmosphere estimated in this study, those are +4-+6‰ ( δ13C) and +1-+3‰ ( δ18O) higher than those reported previously and also those emitted from old, non-catalyst automobiles determined in this study. Recent improvements in functional catalytic converters have enhanced and will enhance the δ13C and δ18O values of CO from automobiles.

  1. 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

  2. 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

  3. 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

  4. Drought Impact on Water - Carbon Interaction in Soil: A Stable Isotopic Approach

    Science.gov (United States)

    Joseph, J.; Weiler, M.; Gessler, A.

    2014-12-01

    Extreme climatic conditions like drought introduce drastic changes in carbon and water dynamics in the plant - soil continuum, starting from carbon assimilation till carbon allocation in the soil, root water uptake till transpiration via leaves. Our objective was to study the drought impact on the dynamics of Carbon, and water cycles, as well as the interaction between them under extreme climatic conditions in the plant soil continuum. The first phase of the experiment involved 13CO2 pulse labeling of drought exposed and well-water beech microcosms, during which we monitored the 13C allocation to roots, and in the soil by measuring the CO2 concentration, ∂13C, and ∂18O of root derived CO2. We found that drought had a significant impact on, a) carbon assimilation, allocation, and translocation rate in the plant - soil system. The drought stressed plants not only assimilated fewer amounts of CO2, but also translocation of those assimilates belowground was extremely slow, and root respiration was low in comparison the well watered control plants. The second phase involved rewetting of the drought chambers (and the application of similar amounts of water to the controls) using D218O enriched water followed by an additional 13CO2 pulse labeling approach so as to study the effects of drought on the infiltration patterns of a precipitation event as well as the recovery of the carbon relations of previously drought stressed beech saplings.

  5. 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.

  6. 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

  7. 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)

  8. Stable isotopes and the environment

    International Nuclear Information System (INIS)

    Whereas traditionally, stable isotope research has been directed towards resource exploration and development, it is finding more frequent applications in helping to assess the impacts of resource utilization upon ecosystems. Among the many pursuits, two themes are evident: tracing the transport and conversions of pollutants in the environment and better understanding of the interplay among environmental receptors, e.g. food web studies. Stable isotope data are used primarily to identify the presence of pollutants in the environment and with a few exceptions, the consequence of their presence must be assessed by other techniques. Increasing attention has been given to the isotopic composition of humans with many potential applications in areas such as paleodiets, medicine, and criminology. In this brief overview examples are used from the Pacific Rim to illustrate the above concepts. 26 refs., 1 tab., 3 figs

  9. 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.

  10. 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.

    aerosols over AS are characterized by significantly higher TC/TN ratios (approx.50 + or - 10) compared to aerosol over Indian cities (5.6 + or - 2.6) as well as over BOB (6.8 + or - 12.5), most likely due to having significant inorganic carbon contributed...

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

    Science.gov (United States)

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

  12. 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.

  13. 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.

  14. 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...

  15. Changes in carbon sources fueling benthic secondary production over depth and time: coupling Chironomidae stable carbon isotopes to larval abundance.

    Science.gov (United States)

    Frossard, Victor; Verneaux, Valérie; Millet, Laurent; Magny, Michel; Perga, Marie-Elodie

    2015-06-01

    Stable C isotope ratio (δ(13)C) values of chironomid remains (head capsules; HC) were used to infer changes in benthic C sources over the last 150 years for two French sub-Alpine lakes. The HCs were retrieved from a series of sediment cores from different depths. The HC δ(13)C values started to decrease with the onset of eutrophication. The HC δ(13)C temporal patterns varied among depths, which revealed spatial differences in the contribution of methanotrophic bacteria to the benthic secondary production. The estimates of the methane (CH4)-derived C contribution to chironomid biomass ranged from a few percent prior to the 1930s to up to 30 % in recent times. The chironomid fluxes increased concomitantly with changes in HC δ(13)C values before a drastic decrease due to the development of hypoxic conditions. The hypoxia reinforced the implication for CH4-derived C transfer to chironomid production. In Lake Annecy, the HC δ(13)C values were negatively correlated to total organic C (TOC) content in the sediment (Corg), whereas no relationship was found in Lake Bourget. In Lake Bourget, chironomid abundances reached their maximum with TOC contents between 1 and 1.5 % Corg, which could constitute a threshold for change in chironomid abundance and consequently for the integration of CH4-derived C into the lake food webs. Our results indicated that the CH4-derived C contribution to the benthic food webs occurred at different depths in these two large, deep lakes (deep waters and sublittoral zone), and that the trophic transfer of this C was promoted in sublittoral zones where O2 gradients were dynamic. PMID:25630956

  16. Infant feeding practice in medieval Japan: stable carbon and nitrogen isotope analysis of human skeletons from Yuigahama-minami.

    Science.gov (United States)

    Tsutaya, Takumi; Shimomi, Akina; Nagaoka, Tomohito; Sawada, Junmei; Hirata, Kazuaki; Yoneda, Minoru

    2015-02-01

    A longer breastfeeding duration provides various positive effects in subadult health because of abundant immunological factors and nutrients in human breast milk, and decreases the natural fertility of a population through lactational amenorrhea. In this study, we measured stable carbon and nitrogen isotope ratios in the bone collagen of three adults and 45 subadults from the Yuigahama-minami site (from 12th to 14th century) in Kamakura, the early medieval capital of Japan. Marine foods, C3 -based terrestrial foods, and freshwater fish are the primarily protein sources for adults. The changes in the nitrogen isotope ratios of subadults suggest that the relative dietary protein contribution from breast milk started to decrease from 1.1 years of age and ended at 3.8 years. The age at the end of weaning in the Yuigahama-minami population was greater than that in the typical non-industrial populations, a premodern population in the Edo period Japan, and medieval populations in the UK. Skeletons of townspeople from medieval Kamakura indicate severe nutritional stress (e.g., enamel hypoplasia and cribra orbitalia), yet this longer duration of breastfeeding did not compensate adverse effects for nutritional deficiency. The longer breastfeeding period may have been a consequence of complementary food shortage and bad health of subadults. Kamakura experienced urbanization and population increase in the early medieval period. The younger age-at-death distribution and high nutritional stresses in the Yuigahama-minami population and later weaning, which is closely associated with longer inter-birth interval for mothers, suggests that Kamakura developed and increased its population by immigration during urbanization. PMID:25331669

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

    International Nuclear Information System (INIS)

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

  18. 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.

  19. 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.

    coastlines. Mangroves can act either as a sink for organic matter accumulation, or as reservoirs able to transfer organic and inorganic nutrient to adjacent coastal areas through tidal export (Jennerjahn and Ittekkot 2002; Dittmar et al. 2006). The quantity... until analysis. A portion of the wet sediment from each depth-interval was used for the texture analysis. Sediment texture was determined by pipette method after removing the inorganic carbonates using 10 % HCl and organic matter using 15 % H2O2...

  20. 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

  1. 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.

  2. Compound-specific stable carbon isotopic composition of petroleum hydrocarbons as a tool for tracing the source of oil spills

    International Nuclear Information System (INIS)

    With the increasing demand for and consumption of crude oils, oil spill accidents happen frequently during the transportation of crude oils and oil products, and the environmental hazard they pose has become increasingly serious in China. The exact identification of the source of spilled oil can act as forensic evidence in the investigation and handling of oil spill accidents. In this study, a weathering simulation experiment demonstrates that the mass loss of crude oils caused by short-term weathering mainly occurs within the first 24 h after a spill, and is dominated by the depletion of low-molecular weight hydrocarbons (18n-alkanes). Short-term weathering has no significant effect on δ13C values of individual n-alkanes (C12-C33), suggesting that a stable carbon isotope profile of n-alkanes can be a useful tool for tracing the source of an oil spill, particularly for weathered oils or those with a relatively low concentration or absence of sterane and terpane biomarkers

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

    International Nuclear Information System (INIS)

    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 δ13C 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 δ13Cmoss became less negative. With measurements of atmospheric CO2 and δ13CO2, 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 δ13Cmoss 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 13C discrimination of bryophytes might increase with elevated N deposition.

  4. 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.

  5. Use of stable carbon and nitrogen isotopes to trace the larval striped bass food chain in the Sacramento-San Joaquin Estuary, California, April to September 1985

    Science.gov (United States)

    Rast, Walter; Sutton, J.E.

    1989-01-01

    To assess one potential cause for the decline of the striped bass fishery in the Sacramento-San Joaquin Estuary, stable carbon and nitrogen isotope ratios were used to examine the trophic structures of the larval striped bass food chain, and to trace the flux of these elements through the food chain components. Study results generally confirm a food chain consisting of the elements, phytoplankton/detritus-->zooplankton/Neomysis shrimp-->larval striped bass. The stable isotope ratios generally become more positive as one progresses from the lower to the higher trophic level food chain components, and no unusual trophic structure was found in the food chain. However, the data indicate an unidentified consumer organism occupying an intermediate position between the lower and higher trophic levels of the larval striped bass food chain. Based on expected trophic interactions, this unidentified consumer would have a stable carbon isotope ratio of about 28/mil and a stable nitrogen isotope ratio of about 8/mi. Three possible feeding stages for larval striped bass also were identified, based on their lengths. The smallest length fish seem to subsist on their yolk sac remnants, and the largest length fish subsist on Neomysis shrimp and zooplankton. The intermediate-length fish represent a transition stage between primary food sources and/or use of a mixture of food sources. (USGS)

  6. 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...

  7. 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

  8. 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.

  9. 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

  10. The production of stable isotopes in Spain

    International Nuclear Information System (INIS)

    The activities developed in the field of the production of stable isotopes by means of ion-exchange chromatography and thermal diffusion techniques are reported. The first method was used to study the separation of the nitrogen and boron isotopes, whereby the separation factor was determined by the break through method. Values ranging from 1,028 to 1,022 were obtained for the separation factor of nitrogen by using ammonium hydroxide solutions while the corresponding values as obtained for boron amounted to 1,035-1,027 using boric acid solutions. Using ammonium chloride or acetate and sodium borate, respectively, resulted in the obtention of values for the separation factor approaching unity. The isotopic separation has been carried out according to the method of development by displacement. The separation of the isotopes of the noble gases, oxygen, nitrogen and carbon has been accomplished resorting to the method of thermal diffusion. (Author) 16 refs

  11. 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.

  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

    2016-01-01

    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. PMID:27270951

  13. 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.

  14. High-resolution stable carbon isotope monitoring indicates variable flow dynamic patterns in a deep saline aquifer at the Ketzin pilot site (Germany)

    International Nuclear Information System (INIS)

    Highlights: • Isotopically very distinct kinds of CO2 are injected at the Ketzin pilot site. • We used these isotope variances at the injection well as a tracer input signal. • We found none of these signals at a monitored observation well. • This indicates that CO2 is immobilised at this point in the reservoir. • After immobilization, the δ13CCO2 value was altered by fractionation processes. - Abstract: Stable isotopes of injected CO2 act as useful tracers in carbon capture and storage (CCS) because the CO2 itself is the carrier of the tracer signal and remains unaffected by sorption or partitioning effects. At the Ketzin pilot site (Germany), carbon stable isotope composition (δ13C) of injected CO2 at the injection well was analyzed over a time period of 4 months. Occurring isotope variances resulted from the injection of CO2 from two different sources (an oil refinery and a natural gas-reservoir). The two gases differed in their carbon isotope composition by more than 27‰. In order to find identifiable patterns of these variances in the reservoir, more than 250 CO2-samples were collected and analyzed for their carbon isotope ratios at an observation well 100 m distant from the injection well. An isotope ratio mass spectrometer connected to a modified Thermo Gasbench system allowed quick and cost effective isotope analyses of a high number of CO2 gas specimens. CO2 gas from the oil refinery (δ13C = −30.9‰, source A) was most frequently injected and dominated the reservoir δ13C values at the injection site. Sporadic injection of the CO2 from the natural gas-reservoir (δ13C = −3.5‰, source B) caused isotope shifts of up to +5‰ at the injection well. These variances provided a potential ideal tracer for CO2 migration behavior. Based on these findings, tracer input signals that were injected during the last 2 years of injection could be reconstructed with the aid of an isotope mixing model and CO2 delivery schedules. However, in contrast to

  15. 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

  16. Stable isotope measurements of atmospheric CO2

    International Nuclear Information System (INIS)

    The measurement of stable carbon isotope ratios of atmospheric carbon dioxide, δ13CO2 are useful for partitioning surface-atmospheric fluxes into terrestrial and oceanic components. δC18OO also has potential for segregating photosynthetic and respiratory fluxes in terrestrial ecosystems. Here we describe in detail the techniques for making these measurements. The primary challenge for all of the techniques used to measure isotopes of atmospheric CO2 is to achieve acceptable accuracy and precision and to maintain them over the decades needed to observe carbon cycle variability. The keys to success such an approach are diligent intercalibrations of laboratories from around the world, as well as the use of multiple techniques such as dual inlet and GC-IRMS and the intercomparison of such measurements. We focus here on two laboratories, the Stable Isotope Lab at the Institute for Arctic and Alpine Research (INSTAAR) at the University of Colorado is described and the Commonwealth Scientific and Industrial Research Organisation - Atmospheric Research (CSIRO). Different approaches exist at other laboratories (e.g. programs operated by Scripps Institution of Oceanography (SIO) and The Center for Atmospheric and Oceanic Studies, Toboku University (TU)) however these are not discussed here. Finally, we also discuss the recently developed Gas Chromatography - Isotope Ratio Mass Spectrometry (GC-IRMS) technique which holds significant promise for measuring ultra-small samples of gas with good precision. (author)

  17. Carbon-14, tritium, stable isotope and chemical measurements on thermal waters from the Tauranga region

    International Nuclear Information System (INIS)

    The chemical compositions of groundwater from the Tauranga region are affected to varying degrees by reducing conditions due to buried organic matter. The levels of some dissolved constituents are also affected by mixing with sea water contained within the rocks and by rock-water interaction. Dissolved gas compositions range from oxygen-bearing to methane-bearing reflecting the varying redox conditions. Excess air may be present but further experiments are necessary to confirm this. Apparent ages deduced from carbon-14 measurements (corrected using 12C dilution and 13C fractionation methods) range from 2-25,000 years, suggesting that some of the waters were recharged during late Pleistocene or early Holocene time. ΔD and Δ18 O values of the oldest waters are slightly more negative than those of younger samples; this may indicate recharge during a cooler climate, in agreement with the 14C ages. Very low but significantly non-zero tritium contents (TR=(0.007-0.059)+-0.007) were measured using the high tritium-enrichment facilities at INS and the very low-background counters at the University of Bern. The tritium is thought to derive from contamination or nuclear reactions in the aquifer rocks rather than from recharge water

  18. Semi-automatic determination of the carbon and oxygen stable isotope compositions of calcite and dolomite in natural mixtures

    International Nuclear Information System (INIS)

    A semi-automatic, on-line method was developed to determine the δ13C and δ18O values of coexisting calcite and dolomite. An isotopic mass balance is used to calculate the compositions of dolomite after having measured that of calcite and of the “bulk” sample. The limit of validity of this method is established by performing isotopic measurements of artificial mixtures made of precisely weighted and isotopically-characterised dolomite and calcite. The accuracy and repeatability of the calculation of dolomite δ13C and δ18O are statistically determined with a Monte-Carlo procedure of error propagation. Stable isotope ratios are determined by using an automated MultiPrep™ system on-line with an isotope-ratio mass-spectrometer (IRMS). The reaction time and the temperature of reaction were optimised by comparing the results with the isotopic composition of known mixtures. The best results were obtained by phosphoric acid digestion after 20 min at 40 °C for calcite and 45 min at 90 °C for dolomite. This procedure allows an accurate determination of the isotopic ratios from small samples (300 μg). Application of this protocol to natural mixtures of calcite and dolomite requires the accurate determination of the relative abundance of calcite and dolomite by combining Mélières manocalcimetry (MMC) and X-ray diffractometry (XRD).

  19. 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...

  20. Molecular sieve isolation technique for use in stable carbon isotope analysis of individual long-chain n-alkanes in crude oil

    International Nuclear Information System (INIS)

    An isolation procedure of microgram amounts of long-chain n-alkanes from crude oil using molecular sieve was examined for its applicability to stable carbon isotope analysis by gas chromatography/isotope ratio mass spectrometry (GC/IRMS). The procedure examined is as follows: molecular sieve (type 5A, 200 mg) in 1 ml of isooctane solvent are mixed with a saturated hydrocarbon fraction extracted from an appropriate amount (approx. 20 mg) of crude oil and stayed at room temperatures for more than 3 hours. Long-chain n-alkanes are isolated by extraction with n-hexane after dissolution of the resulting molecular sieve with 47% hydrofluoric acid solution. The recoveries were 90±6% for C15-C34 n-alkanes when their total amounts applied do not exceed 1.4 mg. No effect of the isolation procedure on carbon isotope ratios of n-alkanes was observed. (author)

  1. 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

  2. Use of a stable carbon isotope to assess the efficiency of a drinking water treatment method with CO[sub]2

    OpenAIRE

    Poberžnik, Mojca; Leis, Albrecht; Lobnik, Aleksandra

    2012-01-01

    CO2 gas with a special isotopic signature (?13C = -35.2% vs. VPDB) was used as a marker to evaluate the efficiency of a drinking water treatment method and the effect of an ultrasonic (US) stirrer. This treatment was developed to prevent precipitation and corrosion effects in water-supply systems. The research work was performed using a laboratory-scale pilot plant that was filled with tap water. The stable isotope analyses of ?13C-DIC (Dissolved Inorganic Carbon) in the water samples indicat...

  3. 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...

  4. Field based stable isotope analysis of CO2 by mid-infrared laser spectroscopy at a pilot site for carbon storage

    Science.gov (United States)

    Jost, H. J. H.; Van Geldern, R.; Nowak, M. E.; Zimmer, M.; Szizybalski, A.; Myrttinen, A.; Barth, J.

    2014-12-01

    A newly developed and commercially available isotope ratio laser spectrometer for CO2 analyses has been tested during a 10-day field monitoring campaign at the Ketzin pilot site for CO2 storage in northern Germany. 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 minutes 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 2σ analytical precision (high precision and accurate real-time table isotope data directly in the field. The injected CO2 tracer had a distinct δ13C value that was largely different from the reservoir background value. The laser spectroscopy data revealed a prior to this study unknown, intensive dynamic with fast changing δ13C 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 new technique might contribute to a better tracing of the migration of the underground CO2 plume and help to ensure the long-term integrity of the reservoir.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. Application of stable isotope to breath test

    International Nuclear Information System (INIS)

    Needles to say, radioisotopes have good characteristics as a tracer for examining biological functions. In fact, scyntigraphy is widely used over Japan. It is true, however, that there are some difficulties in applying radioisotopes to humans. Thus, greater attention began to be attracted to stable isotopes in the late 1960s, because these substances can be used for infants and pregnant women. They can be stored for a long period of time since they do not suffer damping as in the case of radioisotopes. In addition to serving as a tracer, stable isotopes can provide structural-chemical information including the position of isotope labels, and the mass and atomic composition of fragment ions. Such techniques as NMR spectroscopy is employed for this purpose. The method is currently used to perform examinations of congenital metabolic disorders. The carbon isotopes of 13C and 14C are used for breath test. Compounds labeled with these isotopes are administered and their ratio to the total CO2 in breath is measured to diagnose diseases. In the early 1970s, 13C has come into use for breath test. Similar breath test is applied to diagnosis of the bacterial overgrowth syndrome and ileal dysfunction syndrome. (Nogami, K.)

  11. New Stable Isotope Tropical Paleoclimate Proxies

    Science.gov (United States)

    Lawrence, J. R.

    2005-05-01

    Organized tropical rain systems such as tropical cyclones (TC) and mesoscale convective systems (MCS) produce both water vapor and rainfall with distinctly low isotope ratios. This lowering is caused by recyling of water in organized systems. Therefore, fresh water carbonate organisms have considerable potential to act as proxy recorders of these systems. Ostracoda are ephemeral making them especially attractive candidates. Tropical trees offer another opportunity because the low isotopic spikes produced in both soil waters when heavy rains result and ambient water vapor surronding the trees may be recorded in the tree cellulose. Ostracoda living in the surface waters derived from Tropical Storm Allison (2001) document the passage of the storm in their oxygen isotope ratios. The stable isotopic composition of water vapor along the southwest coast of Mexico shows considerable variation in response to TC and MCS activity offshore even when no rain falls in the region. Potentially a long-term record of this activity may be found in the stable isotopic composition of trees providing low elevation trees of sufficient longevity can be found.

  12. 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

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

    Science.gov (United States)

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

    2016-04-19

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

  14. 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....

  15. 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).

  16. 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.

  17. 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

  18. 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.

  19. Organic synthesis with stable isotopes

    International Nuclear Information System (INIS)

    Some general considerations concerning organic synthesis with stable isotopes are presented. Illustrative examples are described and discussed. The examples include DL-2-amino-3-methyl-13C-butanoic-3,4-13C2 acid (DL-valine-13C3); methyl oleate-1-13C; thymine-2,6-13C2; 2-aminoethanesulfonic-13C acid (taurine-13C); D-glucose-6-13C; DL-2-amino-3-methylpentanoic-3,4-13C2 acid (DL-isoleucine-13C2); benzidine-15N2; and 4-ethylsulfonyl-1-naphthalene-sulfonamide-15N

  20. 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...

  1. 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.

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

    OpenAIRE

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

    2015-01-01

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

  3. Coupled transformation of inorganic stable carbon-13 and nitrogen-15 isotopes into higher trophic levels in a eutrophic shallow lake

    International Nuclear Information System (INIS)

    Enclosure and bag experiments were done in a eutrophic shallow lake with simultaneous use of inorganic 13C and 15N isotopes. It was demonstrated that coupled transformation of inorganic carbon and nitrogen can occur into herbivorous zooplankton through phytoplankton. Direct evidence is provided that there is an apparent coupling between photosynthesis and organic nitrogen uptake by phytoplankton during daytime under natural conditions and that the coupling occurs at a constant ratio

  4. 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

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

    Czech Academy of Sciences Publication Activity Database

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

    2015-01-01

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

  6. 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.

  7. 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

  8. 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., III; 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.

  9. 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

  10. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-12-01

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

  12. 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)

  13. 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

  14. Effects of sewage contamination on macro-algae and shellfish at Moa Point, New Zealand, using stable carbon and nitrogen isotopes

    International Nuclear Information System (INIS)

    Stable carbon and nitrogen isotopes have been used to characterise sewage discharge and effects on seaweed (Ulva lactuca L.), blue mussels (Mytilus galloprovincialis), and limpets (Cellana denticulata) from Moa Point Bay, New Zealand. The nitrogen (15N / 14N) ratio is shown to be a good tracer of sewage pollution in Ulva lactuca and associated grazers (Cellana denticulata) as a result of the increased contribution of urea and ammonia to the surrounding marine environment from the sewage outfall. The carbon (13C / 12C) ratio is suggested as a more appropriate sewer tracer for mussels (Mytilus galloprovincialis), which filter feed the particulate organic matter from the effluent. Lower carbon : nitrogen ratios were found in U. lactuca sampled from the outfall region, compared to uncontaminated control sites, however carbon : nitrogen ratios do not vary significantly amongst shellfish species. (author). 18 refs., 4 figs., 2 tabs

  15. Well-based stable carbon isotope leakage monitoring of an aquifer overlying the CO2 storage reservoir at the Ketzin pilot site, Germany

    Science.gov (United States)

    Nowak, Martin; Myrttinen, Anssi; Zimmer, Martin; van Geldern, Robert; Barth, Johannes A. C.

    2014-05-01

    At the pilot site for CO2 storage in Ketzin, a new well-based leakage-monitoring concept was established, comprising geochemical and hydraulic observations of the aquifer directly above the CO2 reservoir (Wiese et al., 2013, Nowak et al. 2013). Its purpose was to allow early detection of un-trapped CO2. Within this monitoring concept, we established a stable carbon isotope monitoring of dissolved inorganic carbon (DIC). If baseline isotope values of aquifer DIC (δ13CDIC) and reservoir CO2 (δ13CCO2) are known and distinct from each other, the δ13CDIC has the potential to serve as an an early indicator for an impact of leaked CO2 on the aquifer brine. The observation well of the overlying aquifer was equipped with an U-tube sampling system that allowed sampling of unaltered brine. The high alkaline drilling mud that was used during well drilling masked δ13CDIC values at the beginning of the monitoring campaign. However, subsequent monitoring allowed observing on-going re-equilibration of the brine, indicated by changing δ13CDIC and other geochemical values, until values ranging around -23 ‰ were reached. The latter were close to baseline values before drilling. Baselineδ13CDIC and δ13CCO2 values were used to derive a geochemical and isotope model that predicts evolution of δ13CDIC, if CO2 from the reservoir would leak into the aquifer. The model shows that equilibrium isotope fractionation would have to be considered if CO2 dissolves in the brine. The model suggests that stable carbon isotope monitoring is a suitable tool to assess the impact of injected CO2 in overlying groundwater aquifers. However, more data are required to close gaps of knowledge about fractionation behaviour within the CO2(g) - DIC system under elevated pressures and temperatures. Nowak, M., Myrttinen, A., Zimmer, M., Wiese, B., van Geldern, R., Barth, J.A.C., 2013. Well-based, Geochemical Leakage Monitoring of an Aquifer Immediately Above a CO2 Storage Reservoir by Stable Carbon

  16. 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

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

    International Nuclear Information System (INIS)

    Since lipids are depleted in 13C relative to proteins and carbohydrates, variations in lipid composition among species and within individuals significantly influence δ13C 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 δ15N. 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 δ13C values without interfering with δ15N 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 δ13C and δ15N variability.

  18. Carbon and nitrogen stable isotopes of well-preserved Middle Pleistocene bone collagen from Schöningen (Germany) and their paleoecological implications.

    Science.gov (United States)

    Kuitems, Margot; van der Plicht, Johannes; Drucker, Dorothée G; Van Kolfschoten, Thijs; Palstra, Sanne W L; Bocherens, Hervé

    2015-12-01

    Carbon and nitrogen stable isotopes in bone collagen can provide valuable information about the diet and habitat of mammal species. However, bone collagen degrades in normal circumstances very rapidly, and isotope analyses are therefore usually restricted to fossil material with a Late Pleistocene or Holocene age. The Middle Pleistocene site of Schöningen, dated to around 300,000 years ago, yielded bones and teeth with an exceptionally good state of collagen preservation. This allowed us to measure reliable biogenic carbon and nitrogen stable isotope ratios for different herbivorous taxa from the families Elephantidae, Rhinocerotidae, Equidae, Cervidae, and Bovidae. The results provide insights regarding the paleoenvironmental setting in which Middle Pleistocene hominins operated. The vegetation consumed by the herbivores from the famous spear horizon originates from open environments. During the climatic Reinsdorf Interglacial optimum, the landscape seems to have been relatively open as well, but certainly included parts that were forested. The results also indicate some niche partitioning; different herbivore species used different plant resources. For instance, the horses seem to have been predominantly browsers, while the straight-tusked elephants were feeding chiefly on grass. PMID:25824673

  19. 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. PMID:27167517

  20. 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.

  1. 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...

  2. 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

  3. 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

  4. 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

  5. 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.

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

    OpenAIRE

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

    2015-01-01

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

  7. 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...

  8. Stable Isotope Enrichment by Thermal Diffusion, Chemical Exchange, and Distillation

    Energy Technology Data Exchange (ETDEWEB)

    Schwind, Dr. Roger A.; Rutherford, Dr. William M.

    1973-03-01

    Applications of stable isotopes in medicine are becoming more widespread. This has resulted from the increased availability and reduced cost of these isotopes and the improved reliability and sensitivity of detection techniques such as carbon-13 nuclear magnetic resonance. Isotopes are used in compounds labeled with either the stable isotope itself, such as carbon-13 and oxygen-18, or with the radioactive isotope that can be produced by irradiating the stable isotope, such as the irradiation of xenon-124 to produce iodine-125. As the demand for stable isotopes increases, larger scale production facilities will be justifiable. The increased size of production facilities should result in yet lower unit selling prices. A large number of methods has been suggested for the separation of stable isotopes. This paper concerns itself with four methods which have proven extremely useful for the separation of the isotopes of low and medium atomic weight elements. The four processes discussed are gas phase thermal diffusion, liquid phase thermal diffusion, chemical exchange, and distillation.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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...

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

    OpenAIRE

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

    2016-01-01

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

  17. 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

  18. Stable isotope analysis of organic carbon in small (µg C) samples and dissolved organic matter using a GasBench preparation device.

    Science.gov (United States)

    Lang, Susan Q; Bernasconi, Stefano M; Früh-Green, Gretchen L

    2012-01-15

    The stable isotopes of organic matter can provide valuable information on carbon cycling dynamics, microbial metabolisms, and past climates. Since bulk measurements may mask dynamic changes to critical portions of the organic pool, researchers are increasingly isolating individual compounds for isotopic analysis. The amount of carbon isolated is frequently small, requiring specialized equipment for its analysis. We present a simple and accurate method to measure the δ(13)C values of µg-amounts of organic compounds and dissolved organic matter in freshwaters using wet oxidation and a GasBench II preparation device. Samples containing 3 µg C can be analyzed with a precision of riparian ground water determined by this method are comparable with those determined with an elemental analyzer on freeze-dried samples of DOC. The low detection limit and the ease with which it can be combined with isolation techniques such as liquid chromatography make this technique attractive for the off-line analysis of organic compounds, and open new possibilities for the development of methodologies for compound-specific carbon isotope analysis of complex mixtures separated by HPLC. PMID:22215572

  19. 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

  20. 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)

  1. 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

  2. DNA Stable-Isotope Probing (DNA-SIP)

    OpenAIRE

    Dunford, Eric A.; Neufeld, Josh D.

    2010-01-01

    DNA stable-isotope probing (DNA-SIP) is a powerful technique for identifying active microorganisms that assimilate particular carbon substrates and nutrients into cellular biomass. As such, this cultivation-independent technique has been an important methodology for assigning metabolic function to the diverse communities inhabiting a wide range of terrestrial and aquatic environments. Following the incubation of an environmental sample with stable-isotope labelled compounds, extracted nucleic...

  3. 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.

  4. 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.

  5. 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

  6. Gas phase thermal diffusion of stable isotopes

    International Nuclear Information System (INIS)

    The separation of stable isotopes at Mound Facility is reviewed from a historical perspective. The historical development of thermal diffusion from a laboratory process to a separation facility that handles all the noble gases is described. In addition, elementary thermal diffusion theory and elementary cascade theory are presented along with a brief review of the uses of stable isotopes

  7. Stable isotope labeled L-tryptophan

    International Nuclear Information System (INIS)

    Stable isotope labeled L-tryptophan is an application of nucleus technology in amino acids. Progresses in stable isotope labeled L-tryptophan in recent years are reviewed.. In the respect of synthesis, in addition to the methods of organic synthesis and isotope exchange, the microbial technology which has the advantage of U-label and construct has been used widely. In the respect of applications, stable isotope labeled L-tryptophan as trace has been used widely in yields of medicine, biology and chemistry et al. Along with the development of protein engineering, molecular biology and peptide drugs, they will have a fine future. (authors)

  8. 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

  9. 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

  10. Medical application of stable isotopes

    International Nuclear Information System (INIS)

    The application of stable isotopes (SI) to clinical examinations was reviewed. As an example of 14C-breath test, the application of 1-14C-cholate to intestinal bacterial overgrowth syndrome was described, and as an example of 13C-breath test, the application of glycine-1-13C-cholate. The breath test using 13C-galactose and 13C-aminopyrine was applied to liver function tests, that using 13C-trioctanoin, fat absorption test, and that using 13C-glycine and 13C-glucose, congenital abnormalities of metabolism. Moreover, studies of sugar metabolism by means of glucose labelled with SI and protein N metabolism by means of compounds labelled with 15N were reported. Measurement of pulmonary extravascular fluid by heavy water, respiratory function test by 4He gas, and movement of bile acid by 2H-bile acid were also reported. The application of SI to metabolic route examination and serum in vitro examination was also described. (Kanao, N.)

  11. 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

  12. Paleoecologies and paleoclimates of late cenozoic mammals from Southwest China: Evidence from stable carbon and oxygen isotopes

    Science.gov (United States)

    Biasatti, Dana; Wang, Yang; Gao, Feng; Xu, Yingfeng; Flynn, Lawrence

    2012-01-01

    To examine paleodiets and habitats of extinct taxa and to understand long-term regional climate change, we determined the carbon and oxygen isotopic compositions of fossil herbivore teeth and soil samples from six localities in Yunnan Province, Southwest China, ranging in age from ˜10 Ma to the present. Although limited in spatial and temporal coverage, these initial results reveal significant changes in the environments and diets of mammalian taxa over the last 10 million years. Prior to 2-3 Ma, while most mammals examined had pure or nearly pure C 3 diets, some individuals consumed a small amount of C 4 grasses (up to 20% C 4). Since then, C 4 grasses became a significant dietary component for most herbivores as indicated by higher enamel-δ 13C values in the Pleistocene Yuanmou Formation and at Shangri-La, most likely reflecting an increased C 4 biomass in the region. The carbon isotope results show that the diets of mammals of ˜2.5-1.75 Ma from Shangri-La ranged from pure C 3 to pure C 4 while 1.7 Ma horses from Yuanmou had 0-70% C 4 grasses in their diets. Mammals living at ˜8-7 Ma in the Yuanmou and Lufeng region had very similar diets and habitats, with similar climatic conditions. Increased C 4 biomass after ˜3-4 Ma suggests a significant change in certain aspects of regional climate, such as increased seasonality of rainfall or an increase in seasonal drought and fires as these factors are important to modern grasslands. The data also show that unlike the Siwalik fauna in the Indian subcontinent, mammals in Yunnan on the southeast side of the Himalayan-Tibetan Plateau lived in an environment dominated by dense forests until ˜3-4 Ma. Nonetheless, both δ 13C values of paleosol carbonates and fossil enamels indicate that C 4 grasses were present in the Yuanmou region in the latest Miocene and Pliocene (˜8-3.5 Ma), likely in greatly dispersed, small patches of open habitats where the forest canopy was broken or on flood plains, and the C 4 biomass

  13. 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

  14. 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.

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    Thanomsak Boonphakdee

    2008-01-01

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

  17. 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

  18. 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.

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

    International Nuclear Information System (INIS)

    The delta13C values of dissolved HCO3- in 75 water samples from 15 oil and gas fields 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 sand-stones which range in age from Eocene through Miocene. The delta13C values of total HCO3- indicate that the carbon in the dissolved carbonate species and carbonate cements is mainly of organic origin. The range of delta 13C values for the HCO3- of these waters is - 20 to 28 per mil relative to PDB. This wide range of delta13C values is explained by three mechanisms. Microbiological degradation of organic matter appears to be the dominant process controlling the extremely low and high delta13C values of HCO3- in the shallow production zones where the subsurface temperatures are less than 800C. The extremely low delta13C values (42- are more than 25 mg/l) and probably result from the degradation of organic acid anions by sulfate-reducing bacteria. The high delta13C values probably result from the degradation of these anions by methanogenic bacteria. 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 800C. The delta13C values of HCO3- for waters from zones with temperatures greater than 1000C result from isotopic equilibration between CO2 and CH4. At these high temperatures, delta13C values of HCO3- decrease with increasing temperatures and decreasing concentrations of these acid anions. (author)

  20. Carbon isotope techniques

    International Nuclear Information System (INIS)

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

  1. 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

  2. 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.

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

    Science.gov (United States)

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

    2007-01-16

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

  4. 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

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

    International Nuclear Information System (INIS)

    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 δ15N values and lower δ13C 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 δ15N) 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 the body

  6. 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

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

    International Nuclear Information System (INIS)

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

  8. 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.

  9. 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 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.

  10. 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.

  11. 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.

  12. On-line stable isotope gas exchange reveals an inducible but leaky carbon concentrating mechanism in Nannochloropsis salina.

    Science.gov (United States)

    Hanson, David T; Collins, Aaron M; Jones, Howland D T; Roesgen, John; Lopez-Nieves, Samuel; Timlin, Jerilyn A

    2014-09-01

    Carbon concentrating mechanisms (CCMs) are common among microalgae, but their regulation and even existence in some of the most promising biofuel production strains is poorly understood. This is partly because screening for new strains does not commonly include assessment of CCM function or regulation despite its fundamental role in primary carbon metabolism. In addition, the inducible nature of many microalgal CCMs means that environmental conditions should be considered when assessing CCM function and its potential impact on biofuels. In this study, we address the effect of environmental conditions by combining novel, high frequency, on-line (13)CO2 gas exchange screen with microscope-based lipid characterization to assess CCM function in Nannochloropsis salina and its interaction with lipid production. Regulation of CCM function was explored by changing the concentration of CO2 provided to continuous cultures in airlift bioreactors where cell density was kept constant across conditions by controlling the rate of media supply. Our isotopic gas exchange results were consistent with N. salina having an inducible "pump-leak" style CCM similar to that of Nannochloropsis gaditana. Though cells grew faster at high CO2 and had higher rates of net CO2 uptake, we did not observe significant differences in lipid content between conditions. Since the rate of CO2 supply was much higher for the high CO2 conditions, we calculated that growing cells bubbled with low CO2 is about 40 % more efficient for carbon capture than bubbling with high CO2. We attribute this higher efficiency to the activity of a CCM under low CO2 conditions. PMID:24844569

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Stable isotope signatures confirm carbon and nitrogen gain through ectomycorrhizas in the ghost orchid Epipogium aphyllum Swartz.

    Science.gov (United States)

    Liebel, H T; Gebauer, G

    2011-03-01

    Epipogium aphyllum is a rare Eurasian achlorophyllous forest orchid known to associate with fungi that form ectomycorrhizas, while closely related orchids of warm humid climates depend on wood- or litter-decomposer fungi. We conducted (13) C and (15) N stable isotope natural abundance analyses to identify the organic nutrient source of E. aphyllum from Central Norway. These data for orchid shoot tissues, in comparison to accompanying autotrophic plants, document C and N flow from ectomycorrhizal fungi to the orchid. DNA data from fungal pelotons in the orchid root cortex confirm the presence of Inocybe and Hebeloma, which are both fungi that form ectomycorrhizas. The enrichment factors for (13) C and (15) N of E. aphyllum are used to calculate a new overall average enrichment factor for mycoheterotrophic plants living in association with ectomycorrhizal fungi (ε(13) C ± 1 SD of 7.2 ± 1.6 ‰ and ε(15) N ± 1 SD of 12.8 ± 3.9 ‰). These can be used to estimate the fungal contribution to organic nutrient uptake by partially mycoheterotrophic plants where fully mycoheterotrophic plants are lacking. N concentrations in orchid tissue were unusually high and significantly higher than in accompanying autotrophic leaf samples. This may be caused by N gain of E. aphyllum from obligate ectomycorrhizal fungi. We show that E. aphyllum is an epiparasitic mycoheterotrophic orchid that depends on ectomycorrhizal Inocybe and Hebeloma to obtain C and N through a tripartite system linking mycoheterotrophic plants through fungi with forest trees. PMID:21309973

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

    International Nuclear Information System (INIS)

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

  19. 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

  20. 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

  1. Chemical and stable carbon isotopic composition of PM2.5 from on-road vehicle emissions in the PRD region and implications for vehicle emission control policy

    Science.gov (United States)

    Dai, S.; Bi, X.; Chan, L. Y.; He, J.; Wang, B.; Wang, X.; Peng, P.; Sheng, G.; Fu, J.

    2015-03-01

    Vehicle emissions are a major source of urban air pollution. In recent decade, the Chinese government has introduced a range of policies to reduce vehicle emissions. In order to understand the chemical characteristics of PM2.5 from on-road vehicle emissions in the Pearl River Delta (PRD) region and to evaluate the effectiveness of control policies on vehicle emissions, 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, in 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, contributing about 9.8% to the PM2.5 emissions. The sum of 27 measured metal elements accounted for 15.2% of 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, polycyclic aromatic hydrocarbons, 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 -25.0‰ on average. An isotopic fractionation of 3.2‰ was found during fuel combustion. Compared to a previous study in Zhujiang tunnel in 2004, emission factors of PM2.5mass, 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 conditions. There are no mandatory national standards to limit metal content from vehicle emissions, which should be a concern of the government. A snapshot of the 2013 characteristic

  2. Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes

    Science.gov (United States)

    Throckmorton, Heather M.; Heikoop, Jeffrey M.; Newman, Brent D.; Altmann, Garrett L.; Conrad, Mark S.; Muss, Jordan D.; Perkins, George B.; Smith, Lydia J.; Torn, Margaret S.; Wullschleger, Stan D.; Wilson, Cathy J.

    2015-11-01

    Arctic soils contain a large pool of terrestrial C and are of interest due to their potential for releasing significant carbon dioxide (CO2) and methane (CH4) to the atmosphere. Due to substantial landscape heterogeneity, predicting ecosystem-scale CH4 and CO2 production is challenging. This study assessed dissolved inorganic carbon (DIC = Σ (total) dissolved CO2) and CH4 in watershed drainages in Barrow, Alaska as critical convergent zones of regional geochemistry, substrates, and nutrients. In July and September of 2013, surface waters and saturated subsurface pore waters were collected from 17 drainages. Based on simultaneous DIC and CH4 cycling, we synthesized isotopic and geochemical methods to develop a subsurface CH4 and DIC balance by estimating mechanisms of CH4 and DIC production and transport pathways and oxidation of subsurface CH4. We observed a shift from acetoclastic (July) toward hydrogenotropic (September) methanogenesis at sites located toward the end of major freshwater drainages, adjacent to salty estuarine waters, suggesting an interesting landscape-scale effect on CH4 production mechanism. The majority of subsurface CH4 was transported upward by plant-mediated transport and ebullition, predominantly bypassing the potential for CH4 oxidation. Thus, surprisingly, CH4 oxidation only consumed approximately 2.51 ± 0.82% (July) and 0.79 ± 0.79% (September) of CH4 produced at the frost table, contributing to <0.1% of DIC production. DIC was primarily produced from respiration, with iron and organic matter serving as likely e- acceptors. This work highlights the importance of spatial and temporal variability of CH4 production at the watershed scale and suggests broad scale investigations are required to build better regional or pan-Arctic representations of CH4 and CO2 production.

  3. 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)

  4. 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)

  5. 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)

    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 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 C2 compounds. 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. Key Words: Acetylene—Fermentation—Isotope fractionation—Enceladus—Life detection. Astrobiology 15, 977–986. PMID:26539733

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  7. Stable carbon isotope reconstructions of diet and paleoenvironment from the late Middle Pleistocene Snake Cave in Northeastern Thailand

    Science.gov (United States)

    Pushkina, Diana; Bocherens, Herve; Chaimanee, Yaowalak; Jaeger, Jean-Jacques

    2010-03-01

    Thailand’s geographical location in the tropics and almost complete, relatively uninterrupted forest cover makes it valuable for paleodiet and paleoclimate research. We present the first dietary and environmental reconstructions in Northeastern Thailand, using stable isotope abundances in mammalian tooth enamel from the late Middle Pleistocene locality, Tham Wiman Nakin (Snake Cave), which reflect a much higher (over 70%) than modern (13%) occurrence of C4 plants. Bovids and cervids appear to have had almost entirely a C4 plant diet. Carnivores consumed a mixture of C3 (suids) and C4 (bovids, cervids) consumers. Rhinoceroses and orangutan appear to have maintained their preference through time for forested or open C3 environment, respectively. 13C/12C from bone bioapatite, horn and hair of modern Southeast Asian mammals almost exclusively demonstrate C3 vegetation dominance. C4 consumption is rare in analysed modern species and it could be related to anthropogenic influences such as ingestion of domestic crops or livestock. Interesting implications emerge in the C4 vegetation distribution in southern Eurasian ecosystems, indicating that Southeast Asia, south of the Tibet, could be part of the global C4 vegetation spread, which occurred around 7 Ma. However, the C4 percentage in ecosystems varied geographically. Despite modern reversal towards C3 habitats due to factors such as increasing CO2, we think that anthropological influences may be responsible for habitat and dietary changes in extant species. Bovids demonstrate the most significant shift in diet and habitat through time, from C4-dominated open habitats to C3-dominated habitats indicative of dense forest understory.

  8. 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...

  9. 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

  10. Aqueous Conditions and Habitability Associated with Formation of a Serpentinite: Using Analyses of Ferric Iron and Stable Carbon Isotopes to Reconstruct Hydrogen Production

    Science.gov (United States)

    Greenberger, R. N.; Mustard, J. F.; Cloutis, E.; Pratt, L. M.; Sauer, P. E.; Mann, P.; Turner, K.; Dyar, M. D.

    2014-12-01

    Serpentine deposits on Mars have generated significant interest because byproducts of serpentinization, H2 and CH4, can be important energy sources for subsurface microbial communities. H2 is produced through Fe2+ oxidation to form magnetite and Fe3+-bearing serpentine. In serpentine, Fe3+ goes into octahedral sites first, then tetrahedral sites [Marcaillou et al., 2011, EPSL]. We use Fe oxidation state and coordination in an Early Ordovician serpentinite in Norbestos, Quebec, as proxies for H2 production and stable isotopes of carbonates to understand past aqueous conditions at the Canadian Space Agency's 2012 Mars Methane Analogue Mission site. Rock outcrops were imaged with a visible hyperspectral imager (420-720 nm), and samples were imaged in the laboratory with the same imager and a near infrared imager (650-1100 nm). Other analyses determined major element chemistry (ICP-AES and C analyses), mineralogy (XRD), Fe phases (Mössbauer spectroscopy), and stable isotopes of carbonates. Fe oxidation state and coordination (tetrahedral vs octahedral) were mapped in samples and outcrops using imaging data. We focused on locations with tetrahedral Fe3+ in serpentine as these are the most serpentinized sites with maximum H2 production. Carbonate samples from ~100-200 m south of a shear zone are enriched in 13C (δ13C up to +16.12‰ vs VPDB) resulting from production of CH4 depleted in 13C in a system closed to C addition but open to CH4 escape. This alteration occurred at elevated temperatures and low water/rock ratios. In the shear zone, lower δ13C values (most Spectroscopy suggests that much of this deposit underwent advanced serpentinization to produce significant H2. Isotopic signatures of carbonates precipitated during serpentinization outside the shear zone illuminate the temperatures (elevated) and chemistries of fluids (high Ca2+, low CO2, alkaline) and gases (H2, CH4) in an ancient habitable environment. These results suggest that serpentinites identified on

  11. Isotopic fingerprints in surficial waters : Stable isotope methods applied in hydrogeological studies

    OpenAIRE

    Kortelainen, Nina

    2007-01-01

    The driving force behind this study has been the need to develop and apply methods for investigating the hydrogeochemical processes of significance to water management and artificial groundwater recharge. Isotope partitioning of elements in the course of physicochemical processes produces isotopic variations to their natural reservoirs. Tracer property of the stable isotope abundances of oxygen, hydrogen and carbon has been applied to investigate hydrogeological processes in Finland. The work...

  12. 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)

  13. 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

  14. Lipid and lipid carbon stable isotope composition of the hydrothermal vent shrimp Mirocaris fortunata: evidence for nutritional dependence on photosynthetically fixed carbon

    OpenAIRE

    Pond, David W; Segonzac, Michel; Bell, Michael V; Dixon, David R.; Fallick, Anthony E.; Sargent, John R.

    1997-01-01

    Mirocaris fortunata were sampled from the Lucky Strike hydrothermal vent area (Eiffel Tower site) on the mid-Atlantic ridge during the French DIVA 2 cruise (June 1994). Small adults (17 to 22 mm total length), although morphologically identical, could be divided into 2 categories on the basis of pigmentation, lipid composition and C-13/C-12 stable isotope ratios of fatty acids. Highly pigmented small adults (8.6 to 9.2 mu g carotenoid shrimp(-1)) contained higher levels of total lipid than si...

  15. 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.

  16. Sediment source detection by stable isotope analysis, carbon and nitrogen content and CSSI in a small river of the Swiss Plateau

    Science.gov (United States)

    SchindlerWildhaber, Yael; Alewell, Christine; Birkholz, Axel

    2014-05-01

    Suspended sediment (SS) and organic matter in rivers can harm the fauna by affecting health and fitness of free swimming fish and by causing siltation of the riverbed. The temporal and spatial dynamics of sediment, carbon (C) and nitrogen (N) during the brown trout spawning season in a small river of the Swiss Plateau were assessed and C isotopes as well as the C/N atomic ratio were used to distinguish autochthonous and allochthonous sources of organic matter in SS loads. The visual basic program IsoSource with 13Ctot and 15N as input isotopes was used to quantify the temporal and spatial sources of SS. We determined compound specific stable carbon isotopes (CSSI) in fatty acids of possible sediment source areas to the stream in addition and compared them to SS from selected high flow and low flow events. Organic matter concentrations in the infiltrated and suspended sediment were highest during low flow periods with small sediment loads and lowest during high flow periods with high sediment loads. Peak values in nitrate and dissolved organic C were measured during high flow and high rainfall, probably due to leaching from pasture and arable land. The organic matter was of allochthonous sources as indicated by the C/N atomic ratio and δ13Corg. Organic matter in SS increased from up- to downstream due to an increase in sediment delivery from pasture and arable land downstream of the river. While the major sources of SS are pasture and arable land during base flow conditions, SS from forest soils increased during heavy rain events and warmer winter periods most likely due to snow melt which triggered erosion. Preliminary results of CSSI analysis of sediment source areas and comparison to SS of selected events indicate that differences in d13C values of individual fatty acids are too small to differentiate unambiguously between sediment sources.

  17. 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.

  18. 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

  19. Stable Carbon and Nitrogen isotopic characterization of bulk atmospheric particles over Indian coastal site (Goa) during monsoon, post-monsoon and winter periods of 2011-12

    Science.gov (United States)

    Yadav, K.; Agnihotri, R.; Sarma, V. V.; Karapurkar, S. G.; Poosarla, P. K.; Kumar, M. D.

    2012-12-01

    respectively; Narukawa et al., 2008). Furthermore, the inter-relationships between C and N isotopic composition with their mass concentrations, aerosol ions, and contemporary meteorological data are being examined and will be presented. Keywords: Bulk aerosols, Goa, Isotopes, carbonaceous material, monsoon References: Agnihotri, R., Mandal, T. K., Karapurkar, S., Naja, M., Gadi, R., Ahammed, Y. N., Kumar, A., Saud, T., and Saxena, M. (2011) Stable carbon and nitrogen isotopic composition of bulk aerosols over India and Northern Indian Ocean, Atmos. Environ., 45, 2828-2835, 2011. Narukawa, M., K. Kawamura, N. Takeuchi, and T. Nakajima (1999) Distributions of dicarboxylic acids and carbon isotopic compositions in aerosols from 1997 Indonesian forest fires, Geophys. Res. Lett., 26(20), 3101-3104, doi:10.1029/1999GL010810.

  20. 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.

  1. 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.

    has received little attention. To fill in this lacuna, during the first Indian expedition to Southern Ocean in 2004, plankton net samples, sediment cores and other physical oceanographic parameters were collected. The isotopic results obtained from...

  2. 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...

  3. 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.

  4. Chemical characterization and stable carbon isotopic composition of particulate Polycyclic Aromatic Hydrocarbons issued from combustion of 10 Mediterranean woods

    OpenAIRE

    Guillon, A.; Ménach, K.; Flaud, P.-M.; Marchand, N.; H. Budzinski; Villenave, E.

    2013-01-01

    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 ...

  5. 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

    2013-03-01

    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/mass spectrometry (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 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 (with δ13CPAH = −28.7 to −26.6‰ from others origins of particulate matter (like vehicular exhaust using isotopic measurements 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 to source tracking.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. Stable carbon isotope variability of bone collagen and hair within a modern population of red kangaroos (Macropus rufus) in south western Queensland: some implications for palaeoecological research

    Energy Technology Data Exchange (ETDEWEB)

    Witt, G.B. [Queensland Univ., St. Lucia, QLD (Australia)

    1997-12-31

    Full text: Before any palaeo-reconstruction work can be attempted using stable isotope analysis of macropod remains it will be necessary to determine the nature of natural variability within contemporary populations. This research indicates that {delta}{sup 13}C of bone collagen is strongly related to age. Furthermore, bone collagen {delta}{sup 13}C not at equilibrium with dietary {delta}{sup 13}C, as indicated by analysis of hair, until animals are several years old. These preliminary data suggest that in younger macropods most carbon in bone collagen has been derived via the mother`s milk which may have undergone fractionation. These findings have significant implications for any palaeoecological research using bone or tooth. Teeth of macropods erupt from the rear of the jaw and move forward in molar progression. Since the rate of eruption is variable, and many of the forward molars are well formed while the joey is still at the pouch, teeth formed early in the life of a macropod may be isotopically distinct from those that develop later. This hypothesis is currently under investigation.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. A low-cost, high-throughput measurement for stable carbon isotope analysis of dissolved organic carbon in fresh water using wet chemical oxidation

    Science.gov (United States)

    Itoh, M.; Tayasu, I.; Yoshimizu, C.; Ohte, N.

    2011-12-01

    Isotope ratio mass spectrometer (IRMS) techniques can be used to analyze the 13C of dissolved organic carbon (DOC) in freshwater samples. The IRMS is usually interfaced with an elemental analyzer (EA) or a wet chemical oxidation (WCO) total organic carbon analyzer. However, the EA-IRMS technique typically requires water samples to be evaporated or freeze-dried, which requires much water and preparation time. Meanwhile, WCO-IRMS requires an expensive total organic carbon (TOC) analyzer for isotopic measurements and the instrument limits the flexibility of the analyses. Here, we propose a new method for analyzing the 13C of DOC in freshwater samples, using WCO. The analyses are performed using a GasBench II head space sampler (Thermo Electron) on-line with an IRMS. This method allows multi-sample processing, which includes the removal of dissolved inorganic carbon (DIC) and oxidation of DOC to CO2 on a dry heating block system. These procedures are conducted in glass vials, which are then placed in an auto sampler and analyzed on the GasBench II connected to the IRMS. It takes 20 min to remove both the DIC and WCO in the glass vials for multiple samples and 10 min to measure the carbon isotope in a sample. The main advantages of this method are the small sample volume requirement (10 μgC in a water sample), rapid analyses (~60 samples/d), and small initial cost if the laboratory already has a GasBench head space sampler. To investigate the performance of our method, we applied it to a solution of standard materials including some amino-acids, hydrogen phthalate, humic acids, and fulvic acids whose δ13C values were determined by EA-IRMS in advance. A good correlation was obtained between the δ13C values with the EA-IRMS measurement and with our method, using 6-ml standard solutions with a concentration of 2 mg-C/L (12 μgC). In our presentation, we will also show the results of DO13C measurements in natural fresh water, including soil water, groundwater, and stream

  17. 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.

  18. 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.

  19. 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

  20. 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.

  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. 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

    The fate and treatability of 1,1,1-TCA by natural and enhanced reductive dechlorination was studied in laboratory microcosms. The study shows that compound-specific isotope analysis (CSIA) identified an alternative 1,1,1-TCA degradation pathway that cannot be explained by assuming biotic reductive...

  3. Use of sulphur and carbon stable-isotope composition of fish scales and muscles to identify the origin of fish

    Science.gov (United States)

    Trembaczowski, Andrzej

    2011-01-01

    δ34S and δ13C analyses were used to determine the origin of trout specimens. The isotope record of their scales and muscles are compared with a database previously obtained from wild- and reared fish coming from Polish rivers and pond farms. The comparison made it possible to find out whether the trout were wild or reared.

  4. 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

  5. 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.)

  6. Carbon isotope analysis of fossil bone apatite

    International Nuclear Information System (INIS)

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

  7. Stable isotopes of captive cetaceans (killer whales and bottlenose dolphins).

    Science.gov (United States)

    Caut, Stéphane; Laran, Sophie; Garcia-Hartmann, Emmanuel; Das, Krishna

    2011-02-15

    There is currently a great deal of interest in using stable isotope methods to investigate diet, trophic level and migration in wild cetaceans. In order to correctly interpret the results stemming from these methods, it is crucial to understand how diet isotopic values are reflected in consumer tissues. In this study, we investigated patterns of isotopic discrimination between diet and blood constituents of two species of cetaceans (killer whale, Orcinus orca, and bottlenose dolphin, Tursiops truncatus) fed controlled diets over 308 and 312 days, respectively. Diet discrimination factors (Δ; mean ± s.d.) for plasma were estimated to Δ(13)C=2.3±0.6‰ and Δ(15)N=1.8±0.3‰, respectively, for both species and to Δ(13)C=2.7±0.3‰ and Δ(15)N=0.5±0.1‰ for red blood cells. Delipidation did not have a significant effect on carbon and nitrogen isotopic values of blood constituents, confirming that cetacean blood does not serve as a reservoir of lipids. In contrast, carbon isotopic values were higher in delipidated samples of blubber, liver and muscle from killer whales. The potential for conflict between fisheries and cetaceans has heightened the need for trophic information about these taxa. These results provide the first published stable isotope incorporation data for cetaceans, which are essential if conclusions are to be drawn on issues concerning trophic structures, carbon sources and diet reconstruction. PMID:21270301

  8. 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

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

    International Nuclear Information System (INIS)

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

  10. 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...

  11. 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...

  12. Diurnal variations of organic molecular tracers and stable carbon isotopic compositions in atmospheric aerosols over Mt. Tai in North China Plain: an influence of biomass burning

    Directory of Open Access Journals (Sweden)

    Z. F. Wang

    2012-04-01

    Full Text Available Organic tracer compounds of tropospheric aerosols, 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 for aerosol samples collected during early and late periods of Mount Tai eXperiment 2006 (MTX2006 field campaign in North China Plain. Total solvent extracts 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 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, 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 and then 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 organic carbon (SOC

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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

  2. Stable isotope probing: uses in metagenomics

    Czech Academy of Sciences Publication Activity Database

    Uhlík, O.; Musilová, L.; Demnerová, K.; Macek, Tomáš; Macková, M.

    Wymondham: Caister Academic Press, 2011 - (Marco, D.), s. 89-97 ISBN 978-1-904455-87-5 Institutional research plan: CEZ:AV0Z40550506 Keywords : Metagenomics * stable isotope probing * high-throughput sequencing * microbial ecology Subject RIV: EI - Biotechnology ; Bionics http://www.horizonpress.com/ metagenomics -advances

  3. 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.

  4. 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

  5. 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

  6. Carbon isotopes in photosynthesis

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  8. 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.

  9. Stable isotope analyses on archived fish scales reveal the long-term effect of nitrogen loads on carbon cycling in rivers.

    Science.gov (United States)

    Roussel, Jean-Marc; Perrier, Charles; Erkinaro, Jaakko; Niemelä, Eero; Cunjak, Richard A; Huteau, Dominique; Riera, Pascal

    2014-02-01

    Stable isotope analysis of organic matter in sediment records has long been used to track historical changes in productivity and carbon cycling in marine and lacustrine ecosystems. While flow dynamics preclude stratigraphic measurements of riverine sediments, such retrospective analysis is important for understanding biogeochemical cycling in running waters. Unique collections of riverine fish scales were used to analyse δ(15) N and δ(13) C variations in the food web of two European rivers that experience different degrees of anthropogenic pressure. Over the past four decades, dissolved inorganic N loading remained low and constant in the Teno River (70°N, Finland); in contrast, N loading increased fourfold in the Scorff River (47°N, France) over the same period. Archived scales of Atlantic salmon parr, a riverine life-stage that feeds on aquatic invertebrates, revealed high δ(15) N values in the Scorff River reflecting anthropogenic N inputs to that riverine environment. A strong correlation between dissolved inorganic N loads and δ(13) C values in fish scales was observed in the Scorff River, whereas no trend was found in the Teno River. This result suggests that anthropogenic N-nutrients enhanced atmospheric C uptake by primary producers and its transfer to fish. Our results illustrate for the first time that, as for lakes and marine ecosystems, historical changes in anthropogenic N loading can affect C cycling in riverine food webs, and confirm the long-term interactions between N and C biogeochemical cycles in running waters. PMID:23765587

  10. 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.

  11. 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.

  12. Utilization of stable isotopes in pharmacology and living matter sciences

    International Nuclear Information System (INIS)

    A survey of the various application fields of stable isotopes in the pharmacological and biomedical domains is presented: utilization of labelled molecules as real tracers (metabolism studies with chromatography and mass spectrometry, studies in bio-pharmacy, bio-availability and bio-equivalence for comparison of medicaments forms, use of stable isotope pulsed doses for medicament kinetics study); methods using voluntary induced isotopic effects in a biologic system; utilization of the carbon 13C/12C ratio and its evolution with time in a living system for in vitro, ex vivo, in vivo studies on man and animals: metabolic tests, dysabsorption tests, bacterial proliferation and infection tests, enzymatic induction and inhibition determination tests

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

    Science.gov (United States)

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

    2015-01-01

    Natural inputs and anthropogenic influences on lakes and their catchments are reflected in the sediment record. In the present study, the extractable organic compounds from sediments in the Chaihe catchment of the Dianchi watershed were analyzed to characterize source inputs. Results show that the sediments are dominated by odd numbered n-alkanes (n-C16-n-C33), maximizing at n-C17, n-C29 and n-C31. Aliphatic hydrocarbon may be composed of terrestrial plants and bacteria. The values of δ(13)C27, δ(13)C29 and δ(13)C31 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 C3 plants in the study area. An isotopic model revealed C3 plant contribution to sedimentary organic matter (OM) ranging from 40.75% to 97.22%. The values of ACL27-33, CPI27-33, OEP, Paq, Pr/Ph, (C27+C29)/2C31, (C21+C23+C25)/3C17 and nC26(-)/nC27(+) are consistent with the C3 plant predominance. A constant CRS model gave the accumulation rates ranging from 2.69 to 8.46mma(-1) spanning 1885-2010. It was concluded that OM transport in the Chaihe catchment was influenced strongly by human activities resulting in enhanced eutrophication. PMID:25261816

  14. 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.

  15. Utilization of stable isotopes in power reactor

    International Nuclear Information System (INIS)

    The stable isotopes, besides uranium, used in EDF power nuclear reactors are mainly the boron 10 and the lithium 7. Boron is used in reactors as a neutrophagous agent for core reactivity control, and lithium, and more especially lithium 7, is extensively used as a solution in PWR moderators for primary fluid pH control. Boron and lithium ore reserves and producers are presented; industrial isotopic separation techniques are described: for the boron 10, they include dissociative distillation (Sulzer process) and separation on anionic resins, and for lithium 7, ion exchange columns (Cogema). 1 tab

  16. [Stable isotopes in biomedical diagnosis and research].

    Science.gov (United States)

    Martínez, J A; Hellerstein, M K; Monreal, I; Neese, R A; Viteri, F E

    1995-01-01

    Atoms that are chemically identical but that differed slightly in weight due to the number of nuclear neutrons are called isotopes stables, meaning that do not degrade spontaneously. Mass spectrometry is the analytical technique to evaluate the enrichment on these isotopes with a variety of applications in the clinical diagnosis of pathological processes and the quantitation of metabolic events such as bacterial growth (Helicobacter pylorii), Phenylketonuria, lactose intolerance, liver and pancreatic function, body composition and energy expenditure, cholesterogenesis, glucose utilization, etc. in an easy, non-invasive and specific way as mass spectrometers develop. PMID:8552917

  17. 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.

  18. 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

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

    International Nuclear Information System (INIS)

    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-C16–n-C33), maximizing at n-C17, n-C29 and n-C31. Aliphatic hydrocarbon may be composed of terrestrial plants and bacteria. The values of δ13C27, δ13C29 and δ13C31 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 C3 plants in the study area. An isotopic model revealed C3 plant contribution to sedimentary organic matter (OM) ranging from 40.75% to 97.22%. The values of ACL27–33, CPI27–33, OEP, Paq, Pr/Ph, (C27 + C29)/2C31, (C21 + C23 + C25)/3C17 and nC26−/nC27+ are consistent with the C3 plant predominance. A constant CRS model gave the accumulation rates ranging from 2.69 to 8.46 mm a−1 spanning 1885–2010. It was concluded that OM transport in the Chaihe catchment was influenced strongly by human activities resulting in enhanced eutrophication. - Highlights: • Strong predominance of odd-numbered n-alkanes maximized at n-C17, n-C29 and n-C31 • Sedimentary OM in the Chaihe catchment was deduced mainly from C3 plants. • Human activities enhanced OM transport, resulting in worse ecosystem

  20. 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)

  1. 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)

  2. 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...

  3. 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...

  4. Transformation of soil organic matter in a Japanese larch forest. Radiocarbon and stable carbon isotope compositions versus soil depth

    International Nuclear Information System (INIS)

    Soil organic matter at a depth of 0-55 cm, collected from a Japanese larch forest area, was separated into particulate organic matter (size >53 μm), particulate organic matter (size 14C and δ13C values were determined. The Δ14C values of particulate matters decreased greatly from 128 per mille to -278 per mille, indicating a relative increase of resistant organic components in particulate matters. That of humic acid matter decreased from 183 per mille to -139 per mille. For these of organic matter fractions at the same depth, the Δ14C values of particulate matter (size >53μm) are smallest and those of humic acid matter are the largest. That indicates that a high contribution of young organic matter to the humic acid matter exists and transformation tendency of particulate matter may be from coarse to small in the particulate size. Positive Δ14C values appeared at a depth of 10 cm, 25 cm, and 35 cm for the particulate organic matter (size >53μm), particulate organic matter (size 14C values of the humic acid matter also infects that the bomb carbon has reached the depth of 35 cm. Additionally, the Δ14C values of these three kinds of organic matters ranged from 50 per mille to 183 per mille at a depth of 0-7 cm, which were not smaller than that of litter in the forest area, indicating high proportion of modern, plants-derived soil organic matter in this depth ranges. The δ13C values increased from -28 per mille to -23 per mille with the increase depth of 0-55 cm. The δ13C values of humic acid matter are approximately less than that of particulate matters at the same depth, which may be explained as a high contribution of young organic matter to the humic acid matter. (author)

  5. 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 precisely assess the total energy expenditure during free-living conditions. The IAAO method uses L-[1-13C]-phenylalanine to assess the availability of amino acids. The application of stable isotopes in human studies makes it possible to conduct nutritional studies in pregnant and lactating women, young infants, children, and adults of all ages because of its safety and low burden compared with previous methods. (author)

  6. Utilization of stable isotopes in medicine

    International Nuclear Information System (INIS)

    The ten lectures given at this round table are presented together with a discussion. Five lectures, relating to studies in which deuterium oxide was employed as a tracer of body water, dealt with pulmonary water measurements in man and animals, the total water pool in adipose subjects, and liquid compartments in children undergoing hemodyalisis. The heavy water is analysed by infrared spectrometry and a new double spectrodoser is described. Two studies using 13C as tracer, described the diagnosis of liver troubles and diabetes respectively. A general review of the perspectives of the application of stable isotopes in clinical medicine is followed by a comparison of the use of stable and radioactive isotopes in France

  7. 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.

  8. Stable isotopes may provide evidence for starvation in reptiles.

    Science.gov (United States)

    McCue, Marshall D; Pollock, Erik D

    2008-08-01

    Previous studies have attempted to correlate stable isotope signatures of tissues with the nutritional condition of birds, mammals, fishes, and invertebrates. Unfortunately, very little is known about the relationship between food limitation and the isotopic composition of reptiles. We examined the effects that starvation has on delta13C and delta15N signatures in the tissues (excreta, carcass, scales, and claws) of six, distantly related squamate reptiles (gaboon vipers, Bitis gabonica; ball pythons, Python regius; ratsnakes, Elaphe obsoleta; boa constrictors, Boa constrictor; western diamondback rattlesnakes, Crotalus atrox, and savannah monitor lizards, Varanus exanthematicus). Analyses revealed that the isotopic composition of reptile carcasses did not change significantly in response to bouts of starvation lasting up to 168 days. In contrast, the isotopic signatures of reptile excreta became significantly enriched in 15N and depleted in 13C during starvation. The isotopic signatures of reptile scales and lizard claws were less indicative of starvation time than those of excreta. We discuss the physiological mechanisms that might be responsible for the starvation-induced changes in 13C and 15N signatures in the excreta, and present a mixing model to describe the shift in excreted nitrogen source pools (i.e. from a labile source pool to a nonlabile source pool) that apparently occurs during starvation in these animals. The results of this study suggest that naturally occurring stable isotopes might ultimately have some utility for characterizing nitrogen and carbon stress among free-living reptiles. PMID:18613003

  9. Changes to Lignin Phenol and Hydroxy Alkanoic Acid yStable Carbon Isotope Composition and Concentration in ySoil Fractions from a Grassland/Woodland Conversion in ya Subtropical Savannay</