Sample records for abundance stable isotope

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

    NASA Technical Reports Server (NTRS)

    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.

  2. Natural abundances of stable isotopes trace anthropogenic N and C in an urban stream

    Microsoft Academic Search

    Amber J. Ulseth; Anne E. Hershey

    2005-01-01

    Important ecological services of low-order streams are greatly affected by urbaniza- tion. North Buffalo Creek, in the headwaters of the Cape Fear River basin in Greensboro, North Carolina, receives point- and nonpoint-source pollutants. Natural abundances of the stable isotopes of C( 13C) and N (15N) were used to determine the influence of anthropogenic nutrients on seston d15N, nutrient concentrations, C\\/N

  3. Atmospheric Trace Gas Abundances and Stable Isotope Ratios via IR-LIF

    NASA Technical Reports Server (NTRS)

    Blake, Geoffrey A.

    2004-01-01

    We propose to develop new technologies with support provided by PIDDP that will enable the in situ measurements of abundances and stable isotope ratios in important radiatively and biogenically active gases such as carbon dioxide, carbon monoxide, water, methane, nitrous oxide, and hydrogen sulfide to very high precision (0.1 per mil or better for the isotopic ratios, for example). Such measurements, impossible at present, could provide pivotal new constraints on the global (bio)geochemical budgets of these critical species, and could also be used to examine the dynamics of atmospheric transport on Mars, Titan, and other solar system bodies. We believe the combination of solid state light sources with imaging of the IR laser induced fluorescence (IR-LIF) via newly available detector arrays will make such in situ measurements possible for the first time. Even under ambient terrestrial conditions, the LIF yield from vibrational excitation of species such as water and carbon dioxide should produce emission measures well in excess of ten billion photons/sec from samples volumes of order 1 c.c. These count rates can, in principle, yield detection limits into the sub-ppt range that are required for the in situ isotopic study of atmospheric trace gases. While promising, such technologies are relatively immature, but developing rapidly, and there are a great many uncertainties regarding their applicability to in situ IR-LIF planetary studies. We therefore feel PIDDP support will be critical to developing these new tools, and propose a three-year program to combine microchip near-IR lasers with low background detection axes and state-of-the-art HgCdTe detectors developed for astronomical spectroscopy to investigate the sensitivity of IR-LIF under realistic planetary conditions, to optimize the optical pumping and filtering schemes for important species, and to apply the spectrometer to the non-destructive measurement of stable isotopes in a variety of test samples. These studies form the necessary precursors to the development of compact, lightweight stable isotope/trace gas sensors for future planetary missions.

  4. Temporal variation in mycorrhizal diversity and carbon and nitrogen stable isotope abundance in the wintergreen meadow orchid Anacamptis morio.

    PubMed

    Ercole, Enrico; Adamo, Martino; Rodda, Michele; Gebauer, Gerhard; Girlanda, Mariangela; Perotto, Silvia

    2015-02-01

    Many adult orchids, especially photoautotrophic species, associate with a diverse range of mycorrhizal fungi, but little is known about the temporal changes that might occur in the diversity and functioning of orchid mycorrhiza during vegetative and reproductive plant growth. Temporal variations in the spectrum of mycorrhizal fungi and in stable isotope natural abundance were investigated in adult plants of Anacamptis morio, a wintergreen meadow orchid. Anacamptis morio associated with mycorrhizal fungi belonging to Tulasnella, Ceratobasidium and a clade of Pezizaceae (Ascomycetes). When a complete growing season was investigated, multivariate analyses indicated significant differences in the mycorrhizal fungal community. Among fungi identified from manually isolated pelotons, Tulasnella was more common in autumn and winter, the pezizacean clade was very frequent in spring, and Ceratobasidium was more frequent in summer. By contrast, relatively small variations were found in carbon (C) and nitrogen (N) stable isotope natural abundance, A. morio samples showing similar (15)N enrichment and (13)C depletion at the different sampling times. These observations suggest that, irrespective of differences in the seasonal environmental conditions, the plant phenological stages and the associated fungi, the isotopic content in mycorrhizal A. morio remains fairly constant over time. PMID:25382295

  5. Absolute quantification of protein and post-translational modification abundance with stable isotope–labeled synthetic peptides

    PubMed Central

    Kettenbach, Arminja N; Rush, John; Gerber, Scott A

    2013-01-01

    In the analysis of biological systems, it is of interest to identify the components of the system and to monitor their changes in abundance under different conditions. The AQUA (for ‘absolute quantification’) method allows sensitive and specific targeted quantification of protein and post-translational modifications in complex protein mixtures using stable isotope–labeled peptides as internal standards. Each AQUA experiment is composed of two stages: method development and application to a biological scenario. In the method development stage, peptides from the protein of interest are chosen and then synthesized with stable isotopes such as 13C, 2H or 15N. The abundance of these internal standards and their endogenous counterparts can be measured by mass spectrometry with selected reaction monitoring or selected ion monitoring methods. Once an AQUA method is established, it can be rapidly applied to a wide range of biological samples, from tissue culture cells to human plasma and tissue. After AQUA peptide synthesis, the development, optimization and application of AQUA analyses to a specific biological problem can be achieved in ~1 week. Here we demonstrate the usefulness of this method by monitoring both Polo-like kinase 1 (Plk1) protein abundance in multiple lung cancer cell lines and the extent of Plk1 activation loop phosphorylation (pThr-210) during release from S phase. PMID:21293459

  6. Measurement for isotopic abundances

    Microsoft Academic Search

    1973-01-01

    Review was made on the determination of isotopic abundance ratio by the ; mass spectroscopic method, relation between the abundance ratio and atomic ; weight, problems in the relative measurement of the ratio, standard materials for ; the determination of the abundance ratio and extraterrestrial materials, and ; specific topics on varlous elements. Use of mass spectrographs is classified ;

  7. Stable isotope studies

    SciTech Connect

    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.

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

    PubMed

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

    2015-06-01

    Stable C isotope ratio (?(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 ?(13)C values started to decrease with the onset of eutrophication. The HC ?(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 ?(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 ?(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

  9. Quantitative, Multiplexed Assays for Low Abundance Proteins in Plasma by Targeted Mass Spectrometry and Stable Isotope Dilution*S

    PubMed Central

    Keshishian, Hasmik; Addona, Terri; Burgess, Michael; Kuhn, Eric; Carr, Steven A.

    2008-01-01

    Biomarker discovery produces lists of candidate markers whose presence and level must be subsequently verified in serum or plasma. Verification represents a paradigm shift from unbiased discovery approaches to targeted, hypothesis-driven methods and relies upon specific, quantitative assays optimized for the selective detection of target proteins. Many protein biomarkers of clinical currency are present at or below the nanogram/milliliter range in plasma and have been inaccessible to date by MS-based methods. Using multiple reaction monitoring coupled with stable isotope dilution mass spectrometry, we describe here the development of quantitative, multiplexed assays for six proteins in plasma that achieve limits of quantitation in the 1–10 ng/ml range with percent coefficients of variation from 3 to 15% without immunoaffinity enrichment of either proteins or peptides. Sample processing methods with sufficient throughput, recovery, and reproducibility to enable robust detection and quantitation of candidate biomarker proteins were developed and optimized by addition of exogenous proteins to immunoaffinity depleted plasma from a healthy donor. Quantitative multiple reaction monitoring assays were designed and optimized for signature peptides derived from the test proteins. Based upon calibration curves using known concentrations of spiked protein in plasma, we determined that each target protein had at least one signature peptide with a limit of quantitation in the 1–10 ng/ml range and linearity typically over 2 orders of magnitude in the measurement range of interest. Limits of detection were frequently in the high picogram/milliliter range. These levels of assay performance represent up to a 1000-fold improvement compared with direct analysis of proteins in plasma by MS and were achieved by simple, robust sample processing involving abundant protein depletion and minimal fractionation by strong cation exchange chromatography at the peptide level prior to LC-multiple reaction monitoring/MS. The methods presented here provide a solid basis for developing quantitative MS-based assays of low level proteins in blood. PMID:17939991

  10. Colorado Plateau Stable Isotope Laboratory

    NSDL National Science Digital Library

    Colorado Plateau Stable Isotope Laboratory (CPSIL)

    This website, hosted by Northern Arizona University, describes stable isotopes. The site defines stable isotopes and how to measure them, and lists their research applications. Many of the advances in ecology and environmental sciences in the past decade have relied on stable isotopes.

  11. Stable Isotope Enrichment Capabilities at ORNL

    SciTech Connect

    Egle, Brian [ORNL; Aaron, W Scott [ORNL; Hart, Kevin J [ORNL

    2013-01-01

    The Oak Ridge National Laboratory (ORNL) and the US Department of Energy Nuclear Physics Program have built a high-resolution Electromagnetic Isotope Separator (EMIS) as a prototype for reestablishing a US based enrichment capability for stable isotopes. ORNL has over 60 years of experience providing enriched stable isotopes and related technical services to the international accelerator target community, as well as medical, research, industrial, national security, and other communities. ORNL is investigating the combined use of electromagnetic and gas centrifuge isotope separation technologies to provide research quantities (milligram to several kilograms) of enriched stable isotopes. In preparation for implementing a larger scale production facility, a 10 mA high-resolution EMIS prototype has been built and tested. Initial testing of the device has simultaneously collected greater than 98% enriched samples of all the molybdenum isotopes from natural abundance feedstock.

  12. Food Resources of Stream Macronivertebrates Determined by Natural-Abundance stable C and N Isotopes and a 15N Tracer Addition

    SciTech Connect

    Mulholland, P. J.

    2000-01-01

    Trophic relationships were examined using natural-abundance {sup 13}C and {sup 15}N analyses and a {sup 15}N-tracer addition experiment in Walker Branch, a 1st-order forested stream in eastern Tennessee. In the {sup 15}N-tracer addition experiment, we added {sup 15}NH{sub 4} to stream water over a 6-wk period in early spring, and measured {sup 15}N:{sup 14}N ratios in different taxa and biomass compartments over distance and time. Samples collected from a station upstream from the {sup 15}N addition provided data on natural-abundance {sup 13}C:{sup 12}C and {sup 15}N:{sup 14}N ratios. The natural-abundance {sup 15}N analysis proved to be of limited value in identifying food resources of macroinvertebrates because {sup 15}N values were not greatly different among food resources. In general, the natural-abundance stable isotope approach was most useful for determining whether epilithon or detritus were important food resources for organisms that may use both (e.g., the snail Elimia clavaeformis), and to provide corroborative evidence of food resources of taxa for which the {sup 15}N tracer results were not definitive. The {sup 15}N tracer results showed that the mayflies Stenonema spp. and Baetis spp. assimilated primarily epilithon, although Baetis appeared to assimilate a portion of the epilithon (e.g., algal cells) with more rapid N turnover than the bulk pool sampled. Although Elimia did not reach isotopic equilibrium during the tracer experiment, application of a N-turnover model to the field data suggested that it assimilated a combination of epilithon and detritus. The amphipod Gammarus minus appeared to depend mostly on fine benthic organic matter (FBOM), and the coleopteran Anchytarsus bicolor on epixylon. The caddisfly Diplectrona modesta appeared to assimilate primarily a fast N-turnover portion of the FBOM pool, and Simuliidae a fast N-turnover component of the suspended particulate organic matter pool rather than the bulk pool sampled. Together, the natural-abundance stable C and N isotope analyses and the experimental {sup 15}N tracer approach proved to be very useful tools for identifying food resources in this stream ecosystem.

  13. Stable isotope laser spectroscopy

    NASA Technical Reports Server (NTRS)

    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 isotopes as one of nature's ecological recorders

    E-print Network

    Ehleringer, Jim

    Stable isotopes as one of nature's ecological recorders Jason B. West1 , Gabriel J. Bowen2 , Thure of the natural variation in stable isotopes of components of ecological systems have provided new insights of spatial scales. Isotope abundances of the molecules in biological materials and geochemical profiles

  15. STABLE ISOTOPES IN PLANT ECOLOGY

    Microsoft Academic Search

    Todd E. Dawson; Stefania Mambelli; Agneta H. Plamboeck; Pamela H. Templer; Kevin P. Tu

    2002-01-01

    ? Abstract The use of stable isotope techniques in plant ecological research has grown steadily during the past two decades. This trend will continue as investigators realize that stable isotopes can serve as valuable nonradioactive tracers and nondestruc- tive integrators of how plants today and in the past have interacted with and responded to their abiotic and biotic environments. At

  16. ISOTOPIC TITANIUM ABUNDANCES IN LOCAL M DWARFS

    SciTech Connect

    Chavez, Joy [Department of Astronomy, University of Texas, 1 University Station, C1400 Austin, TX 78712-0259 (United States); Lambert, David L. [McDonald Observatory, University of Texas at Austin, 1 University Station, C1402 Austin, TX 78712-0259 (United States)], E-mail: jchavez@astro.as.utexas.edu, E-mail: dll@astro.as.utexas.edu

    2009-07-10

    Relative abundances of the five stable isotopes of titanium ({sup 46}Ti to {sup 50}Ti) are measured for 11 M dwarfs belonging to the thin disk (four stars), thick disk (three stars), the halo (one star), and either the thick or the thin disk (three stars). Over the metallicity range of the sample (-1< [Fe/H] <0), the isotopic ratios are approximately constant at the solar system ratios. There is no discernible difference between the isotopic ratios for thin and thick disk stars. Isotopic ratios are in fair accord with recent calculations of Galactic chemical evolution despite the fact that such calculations underpredict [Ti/Fe] by about 0.4 dex at all metallicities.

  17. Metal Stable Isotopes in Paleoceanography

    NASA Astrophysics Data System (ADS)

    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.

  18. Paleoproxies: Heavy Stable Isotope Perspectives

    Microsoft Academic Search

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

    2002-01-01

    Recent advances in isotope ratio mass spectrometry, namely multiple collector ICP-MS and refined TIMS techniques, will significantly enhance the ability to measure heavy stable isotope fractionation, which will lead to the development of a wide array of process-identifying (bio)-geochemical tools. Thus far research in this area is not easily assessable to scientists outside the isotope field. This is due to

  19. Using PLFA Biomarkers and Natural Abundance Stable and Radiocarbon Isotopes to Characterize the Microbial Ecology and Metabolism of Methane Cycling

    NASA Astrophysics Data System (ADS)

    Mills, C. T.; Mandernack, K. W.; Slater, G. F.; Dias, R. F.

    2008-12-01

    Methane generated in the subsurface is a major source of atmospheric CH4, but its release is mitigated by CH4-oxidizing bacteria (methanotrophs). Therefore, it is important to understand the ecology of methanotroph communities in various environments. Phospholipid fatty acid (PLFA) analyses are a particularly useful method for characterizing these communities for two reasons: (1) Many type I and II methanotrophs produce specific PLFA biomarkers that can be used to estimate their populations, and (2) because CH4 is often very depleted in 13C and sometimes 14C, natural abundance ?13CPLFA and ?14CPLFA values can be used to trace the flow of CH4- derived carbon through microbial ecosystems. We used these tools to evaluate the role of methanotrophs in carbon flow in three different environments: (1) a soil column overlying a coal bed methane (CBM) seep in southwest CO, and pristine, oligotrophic groundwaters within (2) sedimentary and (3) granitic host rocks in Japan. In the soil column impacted by CBM seepage, concentrations of the biomarker PLFAs for type I (16:1?8cis) and type II (18:1?8cis) methanotrophs were as high as 13 and 18 nmoles (g dry soil)-1, respectively. Depth profiles of methanotroph PLFA concentrations varied over different sampling dates indicating dynamic populations. ?13CPLFA values of the CBM soils (-25.1 to - 66.9‰) were substantially more negative than those for the control soil (-14.5 to -32.5‰) indicating that CBM is an important carbon source for the CBM-impacted soil microbial community. ?14CPLFA values (-351 to -936‰) indicate the importance of 14C-dead CBM as a carbon source to the microbial communities, contributing 32 to 66% of total carbon in PLFA structures isolated from shallow soils and 67 to 97% for those isolated from deeper soils. The biomarker for type II methanotrophs, comprised 3 and 18% of total PLFAs in sedimentary and granitic groundwaters, respectively. The ?14C values determined for type II methanotroph PLFAs in the sedimentary (- 861‰) and granite (-867‰) waters were very similar to the ?14C values of dissolved inorganic carbon (DIC) in each water (ca -850‰) suggesting that type II methanotrophs ultimately derive all of their carbon from DIC. In contrast, ?13C values of type II PLFAs in the sedimentary (- 93‰) and granite (-60‰) waters indicate that these organisms use different carbon assimilation schemes in each environment. These studies show the utility of PLFA biomarkers and ?13CPLFA and ?14CPLFA values to characterize the in situ metabolisms of methanotrophic bacteria and overall CH4 recycling in diverse environments.

  20. Millimeter-scale variations of stable isotope abundances in carbonates from banded iron-formations in the Hamersley Group of Western Australia

    NASA Technical Reports Server (NTRS)

    Baur, M. E.; Hayes, J. M.; Studley, S. A.; Walter, M. R.

    1985-01-01

    Several diamond drill cores from formations within the Hamersley Group of Western Australia have been studied for evidence of short-range variations in the isotopic compositions of the carbonates. For a set of 32 adjacent microbands analyzed in a specimen from the Marra Mamba Iron Formation, carbon isotope compositions of individual microbands ranged from -2.8 to -19.8 per mil compared to PDB and oxygen isotope compositions ranged from 10.2 to 20.8 per mil compared to SMOW. A pattern of alternating abundances was present, with the average isotopic contrasts between adjacent microbands being 3.0 per mil for carbon and 3.1 per mil for oxygen. Similar results were obtained for a suite of 34 microbands (in four groups) from the Bruno's Band unit of the Mount Sylvia Formation. Difficulties were experienced in preparing samples of single microbands from the Dales Gorge Member of the Brockman Iron Formation, but overall isotopic compositions were in good agreement with values reported by previous authors. Chemical analyses showed that isotopically light carbon and oxygen were correlated with increased concentrations of iron. The preservation of these millimeter-scale variations in isotopic abundances is interpreted as inconsistent with a metamorphic origin for the isotopically light carbon in the BIF carbonates. A biological origin is favored for the correlated variations in 13C and Fe, and it is suggested that the 13C-depleted carbonates may derive either from fermentative metabolism or from anaerobic respiration. A model is presented in which these processes occur near the sediment-water interface and are coupled with an initial oxidative precipitation of the iron.

  1. Environmental and biomedical applications of natural metal stable isotope variations

    USGS Publications Warehouse

    Bullen, T.D.; Walczyk, T.

    2009-01-01

    etal stable isotopes are now being used to trace metal contaminants in the environment and as indicators of human systemic function where metals play a role. Stable isotope abundance variations provide information about metal sources and the processes affecting metals in complex natural systems, complementing information gained from surrogate tracers, such as metal abundance ratios or biochemical markers of metal metabolism. The science is still in its infancy, but the results of initial studies confirm that metal stable isotopes can provide a powerful tool for forensic and biomedical investigations.

  2. Stable Isotopes and M&Ms

    NSDL National Science Digital Library

    Roman de Jesus

    Students are often confused by the concepts of stable isotope signatures and conventional notation. This activity is designed to introduce students to the del notation (isotopic signature), fractionation, and end member mixing of stable isotopes using familiar objects disguised as isotopes. The activity does not explain the physical manifestation of why isotopic fractionation occurs, but does explain the concepts that one easily observes when interpreting stable isotope data sets.

  3. Use of stable isotopes to determine compliance.

    PubMed

    Schwarcz, H P

    1984-12-01

    The natural variation in the abundance of stable isotopes of light elements (C, H, O, N) in humans is less than 0.5%. Much larger variations can be induced through administration of drugs labeled with enriched isotopes of these elements. Such labels thus can be used as tracers of compliance. Variations of several percent can be generated without adverse physiological effect. An example is presented of the use of deuterium oxide as a tracer, and a scheme of sampling moisture in expired air is proposed, in which the subject can easily collect a sample and present it for rapid analysis. Tracer levels can be used to estimate the degree of compliance. The labeled compound can be selected to match the drug being tested with respect to residence time in the body. Except for deuterium, the cost of such stable isotope tracers is at present prohibitive. The main problem with the use of stable isotopes in compliance studies is the cost of the tracer, a biologically acceptable substance labeled with a rare-stable isotope. Our original experiments were carried out using 13C-glucose, which costs at present about $600/g. To carry out a tracer experiment on an individual, approximately 10 mg of uniformly labeled tracer would be administered, which would result in a 5% shift of the 13C/12C ratio, which is easily detectable. To minimize the cost of such a study, we proposed utilizing the cheapest enriched light isotope that is available, namely, deuterium. Using a ratio-detecting mass spectrometer in which a sample is compared with a standard, it is possible to detect enrichment or depletion of deuterium with respect to 1H at the level of 0.1%.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6518787

  4. Stable isotopes as one of nature's ecological recorders

    Microsoft Academic Search

    Jason B. West; Gabriel J. Bowen; Thure E. Cerling; James R. Ehleringer

    2006-01-01

    Analyses of the natural variation in stable isotopes of components of ecological systems have provided new insights into how these systems function across paleoecological to modern timescales and across a wide range of spatial scales. Isotope abundances of the molecules in biological materials and geochemical profiles are viewed as recorders that can be used to reconstruct ecological processes or to

  5. 5, 24252444, 2008 Stable isotopes and

    E-print Network

    Paris-Sud XI, Université de

    BGD 5, 2425­2444, 2008 Stable isotopes and multiple sources M. N. Bugalho et al. Title Page of Biogeosciences Stable isotopes as ecological tracers: an efficient method for assessing the contribution Union. 2425 #12;BGD 5, 2425­2444, 2008 Stable isotopes and multiple sources M. N. Bugalho et al. Title

  6. A review of stable water isotopeA review of stable water isotope modellingmodelling

    E-print Network

    Sturm, Christophe "Kristof"

    · Stable water isotope (SWI: H2 18O, HDO) cycle · Equilibrium fractionation · Kinetic fractionation 2 water isotopes in the climate system · Stable water isotope (SWI: H2 18O, HDO) cycle · Equilibrium fractionation · Kinetic fractionation 2. Modelling the stable water isotope cycle · Rayleigh distillation model

  7. Climatic/Hydrologic Oscillations since 155,000 yr B.P. at Owens Lake, California, Reflected in Abundance and Stable Isotope Composition of Sediment Carbonate

    USGS Publications Warehouse

    Menking, K.M.; Bischoff, J.L.; Fitzpatrick, J.A.; Burdette, J.W.; Rye, R.O.

    1997-01-01

    Sediment grain size, carbonate content, and stable isotopes in 70-cm-long (???1500-yr) channel samples from Owens Lake core OL-92 record many oscillations representing climate change in the eastern Sierra Nevada region since 155,000 yr B.P. To first order, the records match well the marine ??18O record. At Owens Lake, however, the last interglaciation appears to span the entire period from 120,000 to 50,000 yr B.P., according to our chronology, and was punctuated by numerous short periods of wetter conditions during an otherwise dry climate. Sediment proxies reveal that the apparent timing of glacial-interglacial transitions, notably the penultimate one, is proxy-dependent. In the grain-size and carbonate-content records this transition is abrupt and occurs at ??? 120,000 yr B.P. In contrast, in the isotopic records the transition is gradual and occurs between 145,000 and 120,000 yr B. P. Differences in timing of the transition are attributed to variable responses by proxies to climate change. ?? 1997 University of Washington.

  8. Uses of stable isotopes in fish ecology

    EPA Science Inventory

    Analyses of fish tissues (other than otoliths) for stable isotope ratios can provide substantial information on fish ecology, including physiological ecology. Stable isotopes of nitrogen and carbon frequently are used to determine the mix of diet sources for consumers. Stable i...

  9. Stable isotope deltas: tiny, yet robust signatures in nature.

    PubMed

    Brand, Willi A; Coplen, Tyler B

    2012-09-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg can be written as+15 ?Ur. PMID:22462621

  10. Stable isotopes and biomarkers in microbial ecology

    Microsoft Academic Search

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

    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 ratio mass spectrometry, and then describe a number of applications in microbial ecology based on degreesC.

  11. Detection of Correlations in Stellar Isotopic Abundances

    NASA Astrophysics Data System (ADS)

    Thomsen, K. A.; Smith, M. S.

    2012-10-01

    The composition of a star changes with time via sequences of thermonuclear reactions. These sequences strongly couple the abundances of all elements to each other. The resulting complex interdependencies often make it difficult to ascertain which isotopic abundances most influence one another. To investigate this, a FORTRAN program has been written which analyzes these abundances over time as predicted by a simulation to determine if they may be correlated. This is accomplished via a looping over all possible pairs of tracked isotopes, quantitatively ascertaining the shapes of the abundance versus time curves for each, and assigning numerical scores to determine if these pairs of curves are correlated, anticorrelated, or uncorrelated. Preliminary results from this study will be presented.

  12. Resources on Isotopes: Fundamentals of Stable Isotope Geochemistry

    NSDL National Science Digital Library

    This is a brief review of some of the fundamentals of stable isotope geochemistry, including definitions, terminology, basic principles, standards, and guidelines on reporting data. Users can follow the link on the top right for the periodic table and read about the isotopic systems of several dozen elements.

  13. Stable isotope composition of Earth's large lakes

    NASA Astrophysics Data System (ADS)

    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, ?18O and ?2H 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 ?18O = -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.

  14. Stable Chlorine Isotopes in Ocean Crust Processes

    NASA Astrophysics Data System (ADS)

    Bach, W.; Layne, G.; Kent, A.

    2003-12-01

    The study of natural variations of Cl isotopic composition in ocean crustal rocks has large potential to further our understanding of geochemical cycling of volatiles and elements soluble in saline aqueous solutions. Studies of oceanic basalt suites to date confirm that Cl abundances are highly sensitive to the addition of saline components - either from addition of subduction-related volatile fluxes in back-arc basins and volcanic arcs or via interaction between magmas and Cl-rich seawater-derived components during melting, magma storage and transport. Recent data suggest that ? 37Cl is much more variable in the marine environment than originally thought, with strongly negative ? 37Cl values (down to -7.5 ‰ ) in marine pore waters and positive values (up to +7 ‰ ) in hydrothermal fluids from oceanic spreading centers. Moreover, mantle-derived magmatic rocks reveal large variations in ? 37Cl (-3 to +11 ‰ ), reflecting mantle heterogeneity as well as assimilation of exogenic Cl by crystallizing magmas. The large isotopic variation in low-Cl basalts has been explained by isotopic heterogeneities of the mantle, with very light ? 37Cl values in rocks from the southwest Chile Ridge that have island arc geochemical affinities and heavy ? 37Cl values in Reykjanes Ridge samples (Stewart, 2000, PhD Thesis, Duke University). The inference is that a slab-flux carries a negative ? 37Cl signature while recycled ocean crust in mantle plumes carries a strongly positive ? 37Cl signature, although this is not well constrained at present. Preferential release of isotopically light Cl from the dewatering sediments is suggested by pore water data from the Barbados and Nankai accretionary prisms with ? 37Cl values down to -7.5 ‰ (Ransom et al. 1995, Geology, 23, 715). Volcanic fumaroles also appear to have negative ? 37Cl values. If this is the case then residual Cl in the subducting slab should become isotopically heavier as 35Cl is preferentially released in the shallow subduction zone. The depleted MORB mantle is believed to have a ? 37Cl between 4 and 7 ‰ , similar to C1-chondrite (Magenheim et al., 1995, EPSL, 131, 427). MORB with high Cl and Cl/K tend to have ? 37Cl close to 0 ‰ , which has been explained by contamination of basaltic magmas with seawater-derived Cl. However, the most evolved ferrobasalts and andesites from oceanic spreading ridges have negative ? 37Cl values, down to -1.7 ‰ (Magenheim, unpublished data). Together with data for oceanic gabbros, the ? 37Cl-[Cl] data for these highly evolved rocks form a trend that could be explained by an AFC-like process, although the fact that the trend extends to negative ? 37Cl values cannot be reconciled with batch mixing of magma and salt or brine. Rather, it indicates that 35Cl is preferentially incorporated into the magma and may be related to diffusive exchange between Cl in brine pools above the melt lens of an axial magma system. A more comprehensive global dataset as well as spot analyses of Cl isotope ratios by IMP-SIMS (e.g., of melt inclusions) and the combination of ? 37Cl with other stable isotope systems (B, Li, O, H) are required before these tentative models for global chlorine cycling and crustal assimilation at spreading ridges can be rigorously evaluated.

  15. Measuring In Vivo Ureagenesis With Stable Isotopes

    PubMed Central

    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 protein intake) are especially high. Isotopes have enabled an appreciation of the degree to which ureagenesis is compromised in patients with urea cycle defects. Indeed, isotopic studies of urea cycle flux correlate well with the severity of cognitive impairment in these patients. Finally, the use of isotopes affords an ideal tool with which to gauge the efficacy of therapeutic interventions to augment residual flux through the cycle. PMID:20338795

  16. Transport of stable isotopes: I: Development of a kinetic continuum theory for stable isotope transport

    Microsoft Academic Search

    L. P. Baumgartner; D. Rumble

    1988-01-01

    Equations are developed describing migration of stable isotopes via a fluid phase infiltrating porous media. The formalism of continuum fluid mechanics is used to deal with the problem of microscopic inhomogeneity. Provision is made explicitly for local equilibrium exchange of isotopes between minerals and fluids as well as for kinetic control of isotopic exchange. Changing characteristic parameters of transport systems

  17. Stable isotopes in Lithuanian bioarcheological material

    NASA Astrophysics Data System (ADS)

    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 Schutkowski. "Diet and social status during the La Tène period in Bohemia: carbon and nitrogen stable isotope analysis of bone collagen from Kutná Hora-Karlov and Radovesice." Journal of Anthropological Archaeology 24.2 (2005): 135-147. Schutkowski, Holger, et al. "Diet, status and decomposition at Weingarten: trace element and isotope analyses on early mediaeval skeletal material." Journal of Archaeological Science 26.6 (1999): 675-685. Zernitskaya, Valentina, et al. "Vegetation pattern and sedimentation changes in the context of the Lateglacial climatic events: Case study of Staroje Lake (Eastern Belarus)." Quaternary International (2014).

  18. Protein-based stable isotope probing

    Microsoft Academic Search

    Nico Jehmlich; Frank Schmidt; Jana Seifert; Felipe Bastida; Martin von Bergen; Hans-Hermann Richnow; Carsten Vogt; Martin Taubert

    2010-01-01

    We describe a stable isotope probing (SIP) technique that was developed to link microbe-specific metabolic function to phylogenetic information. Carbon (13C)- or nitrogen (15N)-labeled substrates (typically with >98% heavy label) were used in cultivation experiments and the heavy isotope incorporation into proteins (protein-SIP) on growth was determined. The amount of incorporation provides a measure for assimilation of a substrate, and

  19. Uncertainty in source partitioning using stable isotopes

    Microsoft Academic Search

    Donald L. Phillips; Jillian W. Gregg

    2001-01-01

    Stable isotope analyses are often used to quan- tify the contribution of multiple sources to a mixture, such as proportions of food sources in an animal's diet, or C3 and C4 plant inputs to soil organic carbon. Linear mixing models can be used to partition two sources with a single isotopic signature (e.g., ?13C) or three sources with a second

  20. Synthesis on evaporation partitioning using stable isotopes

    NASA Astrophysics Data System (ADS)

    Coenders-Gerrits, Miriam; Bogaard, Thom; Wenninger, Jochen; Jonson Sutanto, Samuel

    2015-04-01

    Partitioning of evaporation into productive (transpiration) and non-productive evaporation (interception, soil evaporation) is of highest importance for water management practices, irrigation scheme design, and climate modeling. Despite this urge, the magnitude of the ratio of transpiration over total evaporation is still under debate and poorly understood due to measuring difficulties. However, with the current development in isotope measuring devices, new opportunities arise to untangle the partitioning of evaporation. In this paper we synthesize the opportunities and limitations using stable water isotopes in evaporation partitioning. We will analyze a set of field as well as laboratory studies to demonstrate the different evaporation components for various climate and vegetation conditions using stable isotopes 18O/16O and 2H/1H. Experimental data on evaporation partitioning of crops, grass, shrubs and trees are presented and we will discuss the specific experimental set-ups and data collection methods. The paper will be a synthesis of these studies.

  1. Stable isotopic characterisation of francolite formation

    NASA Astrophysics Data System (ADS)

    McArthur, J. M.; Benmore, R. A.; Coleman, M. L.; Soldi, C.; Yeh, H.-W.; O'Brien, G. W.

    1986-02-01

    Stable isotopic data are presented for 112 samples of francolite from 18 separate phosphate deposits. Values of ? 13C and ? 34S in most offshore deposits suggest formation within oxic or suboxic environments either by carbonate replacement or direct precipitation of francolite from water of normal marine compositions. The exceptions are concretionary francolite from Namibia, which has an isotopic composition in keeping with its formation within organic-rich sediments, and that from offshore Morocco, which has an isotopic signature of the anoxic/suboxic interface. Onshore deposits from Jordan, Mexico, South Africa and, possibly, the Permian Phosphoria Formation in the western U.S.A., are substantially depleted in 18O: they appear to be too altered for deductions to be made about their environments of formation. In other onshore deposits which are unaltered, or minimally altered, the isotopic composition suggests that some formed within sulphate-reducing sediments (Sedhura, Morocco) whilst francolite from the Georgina Basin of Australia formed at the oxic/anoxic boundary, where oxidation of biogenic H 2S decreases the ? 34S of pore water. In general, pelletal samples show non-oxic isotopic signatures, whilst non-pelletal samples show oxic isotopic signatures, but samples from Namibia, Peru (Ica Plateau) and the Californian and Moroccan margins are exceptions to this rule. Morphology may therefore be a misleading indicator of francolite genesis as no definitive relation exists between phosphorite type and isotopic signature.

  2. Stable strontium isotope fractionation in synthetic barite

    NASA Astrophysics Data System (ADS)

    Widanagamage, Inoka H.; Schauble, Edwin A.; Scher, Howie D.; Griffith, Elizabeth M.

    2014-12-01

    The mineral barite (BaSO4) accommodates strontium (Sr) in its crystal structure, providing an archive of Sr-isotopes (87Sr/86Sr and ?88/86Sr) in the highly stable sulfate mineral. We investigated mass dependent stable Sr-isotope fractionation (?88/86Sr = ?88/86Srsolid - ?88/86Srsolution) during inorganic precipitation of barite from a barium-rich solution by addition of sulfate under controlled conditions and compared this to equilibrium isotopic fractionation calculated using Density Functional Theory modeling. Sr-substituted barite is predicted to have lower 88Sr/86Sr than any other studied species, and at 25 °C will be about 0.6-0.7‰ lower than the two modeled Sr(H2O)82+-bearing salts that could approximate aqueous Sr2+. This agrees in direction and order of magnitude with experimental results that estimate equilibrium Sr-isotope fractionation in barite to be 0.3‰ lower than aqueous Sr2+ at ?20 °C. The high ionic strength of some of the precipitating solutions (up to 1 M) and potential differences in the average coordination number of aqueous Sr2+ add to uncertainty in a direct comparison of the calculated equilibrium isotopic fractionation values with the experimental results. Stable Sr-isotope fractionation varied along with the distribution coefficient of Sr [Kd(Sr) = [Sr/Ba]barite/[Sr/Ba]solution], which is a function of both temperature and barite saturation state. However the relationship between mass dependent isotopic fractionation and Kd(Sr) is different for conditions of changing temperature versus barite saturation state. With increasing temperature (from 5 to 40 °C), the barite phase became isotopically lighter (?88/86Sr = -0.29‰ to -0.41‰). Conversely, with increasing saturation state (saturation index of barite = 3.0-4.3) the barite phase became isotopically heavier (?88/86Sr = -0.25‰ to -0.10‰). These observations suggest chemical kinetic effects control isotopic fractionation rather than equilibrium temperature effects. The relationship with saturation state indicates the potential presence of a diffusive boundary layer. Barite crystal morphology appears to be affected by the diffusion rate of solute (sulfate) to the growing crystal surface relative to the overall growth rate of barite crystals during precipitation.

  3. Stable isotope enrichment using a plasma centrifuge

    NASA Astrophysics Data System (ADS)

    Krishnan, Mahadevan; Bures, Brian; Madden, Robert

    2012-10-01

    A primary goal of the Department of Energy's Isotope Development and Production for Research and Applications Program (Isotope Program) within the Office of Nuclear Physics (NP) is to produce isotopes that are in short supply in the U.S. and of which there exists no or insufficient domestic commercial production capability. A vacuum arc plasma centrifuge is a rigid rotor column of metal plasma in which centrifugal forces re-distribute ions radially according to their mass/charge ratio. Early work demonstrated rotation at 2 million rpm and separation of various stable isotopes. The spinning plasma column had a Gaussian flux profile, peaked on the rigid rotor axis. This work adopts a more efficient approach, with the plasma created as a hollow column, wherein the flux is concentrated at larger radii where the centrifugal action is highest. By tailoring the vacuum arc discharge geometry, the rotation rate can also be increased to ˜10 million rpm. Data from Cu, Al and other metal plasmas will be presented and discussed in light of enriched stable isotopes needed for research and medicine.

  4. Quantifying uncertainty in stable isotope mixing models

    NASA Astrophysics Data System (ADS)

    Davis, Paul; Syme, James; Heikoop, Jeffrey; Fessenden-Rahn, Julianna; Perkins, George; Newman, Brent; Chrystal, Abbey E.; Hagerty, Shannon B.

    2015-05-01

    Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, Stable Isotope Analysis in R (SIAR), a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (?15N and ?18O) but all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated mixing fractions.

  5. Stable carbon isotope measurements using laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Sauke, T. B.; Becker, J. F.

    1991-01-01

    The 2300 cm(exp -1) spectral region is especially interesting because (12)CO2 and (13)CO2 bands overlap in such a way that their rotational lines have approximately equal absorbance at the anticipated isotopic ratio (approximately 90) of carbon on Earth and Mars. Pairs of rotational lines we have studied are separated by as little as 0.050 cm(exp -1), but are well resolved with a tunable diode laser. Using sophisticated sweep integration and signal averaging techniques, we have measured the stable isotope ratio in carbon dioxide to a precision of better than 1 percent.

  6. Role of stable isotopes in life--testing isotopic resonance hypothesis.

    PubMed

    Zubarev, Roman A

    2011-04-01

    Stable isotopes of most important biological elements, such as C, H, N and O, affect living organisms. In rapidly growing species, deuterium and to a lesser extent other heavy isotopes reduce the growth rate. At least for deuterium it is known that its depletion also negatively impacts the speed of biological processes. As a rule, living organisms "resist" changes in their isotopic environment, preferring natural isotopic abundances. This preference could be due to evolutionary optimization; an additional effect could be due to the presence of the "isotopic resonance". The isotopic resonance phenomenon has been linked to the choice of earliest amino acids, and thus affected the evolution of genetic code. To test the isotopic resonance hypothesis, literature data were analyzed against quantitative and qualitative predictions of the hypothesis. Four studies provided five independent datasets, each in very good quantitative agreement with the predictions. Thus, the isotopic resonance hypothesis is no longer simply plausible; it can now be deemed likely. Additional testing is needed, however, before full acceptance of this hypothesis. PMID:21641558

  7. Rivers and Stable Isotopes as Indicators of Biogeochemical Gradients

    NASA Astrophysics Data System (ADS)

    Barth, J. A.

    2005-12-01

    Consideration of processes on very small (microbe) to large (catchment) scales become increasingly important in biogeochemical gradient work. In this context, rivers are ideal indicators of biogeochemical gradients for large continental scales when geochemical- and discharge data are combined for flux evaluations. If these are further combined with isotope measurements, sources and turnover of water and dissolved constituents can be quantified. An example study is the combination of GIS-, discharge- and water stable isotope data on the in Clyde River basin in Scotland. Here we determined transpiration with an annual average of 0.489 km3 a-1. When combining this rate with the water use efficiency, the CO2 uptake of the entire basin yielded an annual net primary production (NPP) of 185.2 g C m-2. Compared to other temperate areas this is about half the NPP than expected, which is most likely caused by the predominant cover of grasslands. Therefore, agricultural and forest vegetation schemes could influence continental water balances on time scales of years to decades. In another study on the Lagan River in N. Ireland, stable isotope methods were applied to evaluate the role of carbonate versus silicate dissolution. Of these two types of weathering only silicate dissolution withdraws atmospheric CO2 to be stored in the continental crust over long time periods. A downstream evolution with increasing pH- and ?13CDIC values revealed carbonate dissolution despite their minor abundance in the catchment of less than 5 %. This dominant carbonate signal on the riverine carbon cycle outlines the capacity of buffering anthropogenic influences and CO2 turnover. It should be even more pronounced in other rivers where carbonates usually occupy a larger proportion of the basin geology. Future biogeochemical gradient work on rivers should apply particulate and dissolved organic constituent fluxes. This includes more refined compound specific isotope work on selected pollutants such as TCE, PAH, PCB as well as riverine microbiological considerations. Such expansions meet the challenge of measuring much smaller concentrations compared to groundwater contaminant plumes. Further combinations of stable N, H, O, and S isotope systems would also help to resolve overlapping trends when only carbon isotopes are measured. Apart from combining traditional light stable isotope systems, addition of newly accessible isotope groups by multicollector ICP-MS (i.e. Fe, Cr, Zn) and radioisotope techniques can provide innovative tools for resolving gradients and their biogeochemical cycling within rivers.

  8. Stable isotopic analyses in paleoclimatic reconstruction

    SciTech Connect

    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.

  9. Modeling the dynamics of stable isotope tissue-diet enrichment.

    PubMed

    Remien, Christopher H

    2015-02-21

    Reconstructions of dietary composition and trophic level from stable isotope measurements of animal tissue rely on predictable offsets of stable isotope ratios from diet to tissue. Physiological processes associated with metabolism shape tissue stable isotope ratios, and as such the spacing between stable isotope ratios of diet and tissue may be influenced by processes such as growth, nutritional stress, and disease. Here, we develop a model of incorporation stable isotopes in diet to tissues by coupling stable isotope dynamics to a model of macronutrient energy metabolism. We use the model to explore the effect of changes in dietary intake, both composition and amount, and in energy expenditure, on body mass and carbon and nitrogen stable isotope ratios of tissue. PMID:25457228

  10. The abundances of isotopes in the cosmic radiation

    Microsoft Academic Search

    R. A. Mewaldt

    1989-01-01

    Studies of the isotopic composition of nuclei in the cosmic radiation are reviewed, including abundances of the isotopes of elements from H to Ni (nuclear charge 1isotopic

  11. The abundances of isotopes in the cosmic radiation

    Microsoft Academic Search

    R. A. Mewaldt

    1989-01-01

    Studies of the isotopic composition of nuclei in the cosmic radiation are reviewed, including abundances of the isotopes of elements from H to Ni, together with their implications for cosmic ray origin, acceleration, and transport in the Galaxy. The review focuses on determinations of the composition of cosmic ray source material, and the extent to which the isotopic composition of

  12. Protein-based stable isotope probing.

    PubMed

    Jehmlich, Nico; Schmidt, Frank; Taubert, Martin; Seifert, Jana; Bastida, Felipe; von Bergen, Martin; Richnow, Hans-Hermann; Vogt, Carsten

    2010-12-01

    We describe a stable isotope probing (SIP) technique that was developed to link microbe-specific metabolic function to phylogenetic information. Carbon ((13)C)- or nitrogen ((15)N)-labeled substrates (typically with >98% heavy label) were used in cultivation experiments and the heavy isotope incorporation into proteins (protein-SIP) on growth was determined. The amount of incorporation provides a measure for assimilation of a substrate, and the sequence information from peptide analysis obtained by mass spectrometry delivers phylogenetic information about the microorganisms responsible for the metabolism of the particular substrate. In this article, we provide guidelines for incubating microbial cultures with labeled substrates and a protocol for protein-SIP. The protocol guides readers through the proteomics pipeline, including protein extraction, gel-free and gel-based protein separation, the subsequent mass spectrometric analysis of peptides and the calculation of the incorporation of stable isotopes into peptides. Extraction of proteins and the mass fingerprint measurements of unlabeled and labeled fractions can be performed in 2-3 d. PMID:21127489

  13. STABLE CARBON ISOTOPE ANALYSIS OF NUCLEIC ACIDS TO TRACE SOURCES OF DISSOLVED SUBSTRATES USED BY ESTUARINE BACTERIA

    EPA Science Inventory

    The natural abundance of stable carbon isotopes measured in bacterial nucleic acids that were extracted from estuarine bacterial concentrates were used to trace sources of organic matter for bacteria in.aquatic environments. he stable carbon isotope ratios of P. aeruginosa and nu...

  14. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Lancet, M.S.; Winschel, R.A.; Burke, F.P.

    1991-02-01

    Consol R D is developing and demonstrating stable carbon isotope analysis as a method to quantitatively distinguish coal-derived and petroleum-derived carbon in products from coal/petroleum coprocessing. The approach taken is develop the method, then demonstrate its application on authentic continuous-unit products. The significance of selective isotopic fractionation is being determined and, when necessary, corrections are applied to account for it. Precision, accuracy and range of applicability are being defined. The value of accessory analytical techniques also is being assessed. Previously reported data on samples from HRI bench-scale coprocessing Runs 227-53 (Texas lignite/Maya ASB and Texas lignite/Maya VSB) and 238-1 (Westerholt coal/Cold Lake VSB) were corrected for selective isotopic fractionation. Carbon sourcing was performed on samples from HRI bench-scale coprocessing Run 227-60 (Texas lignite/Maya VSB) and samples from UOP bench-scale coprocessing Run 26 (Illinois 6 coal/Lloydminster vacuum resid); the latter data were corrected for isotopic fractionation, though the former could not be corrected. A paper presented at the 1990 DOE Direct Liquefaction Contractor's Review Meeting is appended. 15 refs., 21 figs., 22 tabs.

  15. MINERAL BIOAVAILABILITY AND METABOLISM DETERMINED BY USING STABLE ISOTOPE TRACERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Definitive data on mineral bioavailability in humans and animals can be obtained by using isotopic tracers. The use of stable isotope tracers to study important issues in mineral nutrition has expanded rapidly in the past two decades, particularly in humans. Stable isotopes have a number of advanta...

  16. Ce isotope abundance in chondritic and HED meteorites

    NASA Astrophysics Data System (ADS)

    Lee, S.; Asahara, Y.; Tanaka, T.; Lee, S. R.

    2011-12-01

    138La, 136Ce and 138Ce are p-process nuclides, and their isotopic abundances are generally low due to their modes of nucleosynthesis compared with other isotopes of La and Ce (139La, 140Ce and 142Ce). Tanimizu et al. (2004) mentioned that, using the 140Ce/142Ce ratio as the normalizing value, 136Ce isotope abundance could be acted as an indicator of p-process nuclide anomaly for extra-terrestrial materials to understand the nucleosynthetic origins of solar system matter. Then, meteoritic primordial composition of Ce isotope provides useful information related with 138La decay system. Especially, combined Ce/Nd isotope data in geological and cosmological materials enable us the modeling of the light REE profiles of the source material. We measured Ce isotope ratio for fifteen meteorites, using 140Ce/142Ce=7.941 as the normalizing value, in order to compare Ce isotope abundance between chondritic and HED meteorites. Of them, Ce isotope abundances from two chondritic meteorites were deviated from the average abundances of other 13 meteorites. In this report, we will discuss cosmochemical significance of Ce isotope anomaly.

  17. Strontium stable isotopes fractionate in the soil environments?

    NASA Astrophysics Data System (ADS)

    Halicz, Ludwik; Segal, Irina; Fruchter, Noa; Stein, Mordechai; Lazar, Boaz

    2008-07-01

    This study shows that the stable isotopic composition of strontium (the 88Sr/ 86Sr ratio expressed as ? 88/86Sr value relative to the NBS987 standard) varies significantly in sedimentary terrestrial environments. The abundances of 86Sr, 88Sr isotopes were analyzed by MC-ICP-MS "Nu Plasma". All studied rocks and waters show ? 88/86Sr values that are distinctly different from the measured NBS987 standard (yielding 0.01 ± 0.05‰, all errors are reported as 2 ?). Modern corals from the northern Gulf of Aqaba, Red Sea yielded significantly different value than seawater (? 88/86Sr = 0.22 ± 0.07‰, compared to 0.35 ± 0.06‰, respectively), in an excellent correlation with the ? 88/86Sr analyses reported by Fietzke and Eisenhauer [Fietzke, J., Eisenhauer, A., 2006. Determination of temperature-dependent stable strontium isotopes ( 88Sr/ 86Sr) fractionation via bracketing standard MC-ICP-MS. Geochm. Geophys. Geosyst. 7 (no. 8)] on other coral samples. All carbonate samples that originated in the marine environment: corals ( porites and acropora from the northern Gulf of Aqaba); Cretaceous limestone and runoff from the Judea Mountains as well as lacustrine evaporitic aragonite (Dead Sea); and Red Sea and Atlantic seawater yield an average ? 88/86Sr value of 0.26 ± 0.1‰. On the other hand, secondary materials (products of chemical weathering) from the terrestrial environment of the Judea Mountain such as terra rossa soil and speleothem calcite (that derives its Sr from the above-lying soil) yielded significantly lower ? 88/86Sr value of - 0.17 ± 0.06‰. This indicates that strontium isotopes fractionate in the soil environment calling for a possible development of strontium isotopes as a tracer for processes of chemical weathering and pedogenesis.

  18. STABLE ISOTOPE DYNAMICS IN SUMMER FLOUNDER TISSUES, WITH APPLICATION TO DIETARY ASSESSMENTS IN CHESAPEAKE BAY

    E-print Network

    Newman, Michael C.

    STABLE ISOTOPE DYNAMICS IN SUMMER FLOUNDER TISSUES, WITH APPLICATION TO DIETARY ASSESSMENTS Growth rates........................................................................18 Isotopic turnover 2: STABLE ISOTOPE ANALYSIS OF SUMMER FLOUNDER DIETS IN CHESAPEAKE BAY

  19. The abundances of elements and isotopes in the solar wind

    NASA Technical Reports Server (NTRS)

    Gloeckler, George; Geiss, Johannes

    1988-01-01

    Studies of the chemical and isotopic composition of the solar wind are reviewed. Solar wind abundance measurements are discussed and solar wind, coronal, and photospheric abundances for elements between H and Fe are presented. Also, consideration is given to the determination of the solar wind isotopic composition of the noble gases using foil collection techniques and the observation of solar wind heavy ions with the mass per charge spectrometer on ISEE-3. Other topics include solar wind observations with solid state detectors, solar wind abundances in the magnetosheath and the plasma sheet, and high-mass resolution measurements of chemical elements and isotopes in the solar wind.

  20. STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS

    EPA Science Inventory

    Stable isotopes are increasingly being used as tracers in ecological studies. One application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include food sources for animals, water sources for plants, pollution sources...

  1. Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii Determination

    E-print Network

    Pachucki, Krzysztof

    Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii along the lithium isotopic chain were determined using a combination of precise isotope shift of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field

  2. Stable Isotopes James R Ehleringer and Thure E Cerling

    E-print Network

    Ehleringer, Jim

    for introduction into the mass spectrometer. The most commonly used approaches involve introducing hydrogen as H2 Element Isotope Abundance (%) Hydrogen 1 H 99.985 2 H 0.015 Carbon 12 C 98.89 13 C 1.11 Nitrogen 14 N 99? Of particular interest for global change studies are vari- ations in the isotopic abundances of hydrogen, carbon

  3. Supporting Information Abundant and Stable Char Residues in Soils

    E-print Network

    Lehmann, Johannes

    S 1 Supporting Information for Abundant and Stable Char Residues in Soils: Implications for Soil, Ames IA 50011, USA. 3 Department of Crop and Soil Sciences, Cornell University, Ithaca, New York 14853 de Arqueologia e Etnologia, Universidade de Sao Paulo, Sao Paulo, SP, 05508-900 Brazil. 6 Department

  4. Lithium Isotopic Abundances in Metal-poor Halo Stars

    Microsoft Academic Search

    Martin Asplund; David L. Lambert; Poul Erik Nissen; Francesca Primas; Verne V. Smith

    2006-01-01

    Very high quality spectra of 24 metal-poor halo dwarfs and subgiants have been acquired with ESO's VLT\\/UVES for the purpose of determining Li isotopic abundances. The derived one-dimensional, non-LTE 7Li abundances from the Li I 670.8 nm line reveal a pronounced dependence on metallicity but with negligible scatter around this trend. Very good agreement is found between the abundances from

  5. Stable Isotopes and Mineral Resource Investigations in the United States

    NSDL National Science Digital Library

    This USGS handout is a page providing a good, brief summary of stable isotope techniques and applications in the geosciences. A map indicating the locations of current USGS stable isotopic studies accompanies the text. A discussion of mineral weathering effects and case studies from ore deposits in Maine and North Carolina complement the general overview.

  6. Energy sources for aquatic animals in the Orinoco River floodplain: evidence from stable isotopes

    Microsoft Academic Search

    S. K. Hamilton; W. M. Lewis; S. J. Sippel

    1992-01-01

    Stable carbon and nitrogen isotope ratios in autotrophs, aquatic invertebrates and fishes from the Orinoco River floodplain of Venezuela reveal that microalgae, including both phytoplankton and epiphytic (attached) forms, are predominant energy sources for many aquatic animals, even though aquatic vascular plants are much more abundant. Floating mats of the grass Paspalum repens and the water hyacinth Eichhornia spp. harbor

  7. Intrinsic stable isotope labeling of plants for nutritional investigations in humans

    Microsoft Academic Search

    Michael A. Grusak

    1997-01-01

    Although plant foods provide an array of nutrients in the human diet, our knowledge of how efficiently these nutrients are absorbed has been limited by our ability to selectively monitor their absorption from a complex food matrix. Intrinsic labeling of plants with low-abundance stable isotopes can provide a safe, traceable product to investigate absorptive phenomena in the gut. Various techniques,

  8. Food web dynamics in the Scotia Sea in summer: A stable isotope study

    Microsoft Academic Search

    G. Stowasser; A. Atkinson; R. A. R. McGill; R. A. Phillips; M. A. Collins; D. W. Pond

    The pelagic food web of the Scotia Sea was studied by analysing natural abundances of nitrogen and carbon stable isotopes of primary producers and pelagic consumers, sampled from the seasonal ice edge in the south to the Antarctic Polar Front in the north. The analysis covered, within a single mid-summer period, particulate organic matter (POM) and 38 taxa, ranging from

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

    Microsoft Academic Search

    Melanie J Leng; Jim D Marshall

    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

  10. INCORPORATING CONCENTRATION DEPENDENCE IN STABLE ISOTOPE MIXING MODELS

    EPA Science Inventory

    Stable isotopes are often used as natural labels to quantify the contributions of multiple sources to a mixture. For example, C and N isotopic signatures can be used to determine the fraction of three food sources in a consumer's diet. The standard dual isotope, three source li...

  11. INCORPORATING CONCENTRATION DEPENDENCE IN STABLE ISOTOPE MIXING MODELS

    EPA Science Inventory

    Stable isotopes are frequently used to quantify the contributions of multiple sources to a mixture; e.g., C and N isotopic signatures can be used to determine the fraction of three food sources in a consumer's diet. The standard dual isotope, three source linear mixing model ass...

  12. LITERATURE SURVEY ON ISOTOPIC ABUNDANCE RATIO MEASUREMENTS - 2001-2005

    SciTech Connect

    HOLDEN, N.E.

    2005-08-13

    Along with my usual weekly review of the published literature for new nuclear data, I also search for new candidates for best measurements of isotopic abundances from a single source. Most of the published articles, that I previously had found in the Research Library at the Brookhaven Lab, have already been sent to the members of the Atomic Weights Commission, by either Michael Berglund or Thomas Walczyk. In the last few days, I checked the published literature for any other articles in the areas of natural variations in isotopic abundance ratios, measurements of isotopic abundance ratios on samples of extra-terrestrial material and isotopic abundance ratio measurements performed using ICPMS instruments. Hopefully this information will be of interest to members of the Commission, the sub-committee on isotopic abundance measurements (SIAM), members of the former sub-committee on natural isotopic fractionation (SNIF), the sub-committee on extra-terrestrial isotope ratios (SETIR), the RTCE Task Group and the Guidelines Task Group, who are dealing with ICPMS and TIMS comparisons. In the following report, I categorize the publications in one of four areas. Measurements performed using either positive or negative ions with Thermal Ionization Mass Spectrometer, TIMS, instruments; measurements performed on Inductively Coupled Plasma Mass Spectrometer, ICPMS, instruments; measurements of natural variations of the isotopic abundance ratios; and finally measurements on extra-terrestrial samples with instrumentation of either type. There is overlap in these areas. I selected out variations and ET results first and then categorized the rest of the papers by TIMS and ICPMS.

  13. The use of stable isotopes to study ecosystem gas exchange

    Microsoft Academic Search

    D. Yakir; L. da S. L. Sternberg

    2000-01-01

    Stable isotopes are a powerful research tool in environmental sciences and their use in ecosystem research is increasing.\\u000a In this review we introduce and discuss the relevant details underlying the use of carbon and oxygen isotopic compositions\\u000a in ecosystem gas exchange research. The current use and potential developments of stable isotope measurements together with\\u000a concentration and flux measurements of CO2

  14. Use of stable isotopes in mineral nutrition research

    SciTech Connect

    Turnlund, J.R.

    1989-01-01

    Stable isotopes are valuable tools for research on mineral bioavailability and metabolism. They can be used as tracers with no exposure to radiation and they do not decay over time. Attempts to use stable isotopes of minerals as metabolic tracers were first described only 25 years ago. There were relatively few reports of their use over the next 15 years, but interest in stable isotopes has expanded markedly in the last 10 years. The advantages of stable isotope tracers are so great that scientists have been willing to accept the laborious and costly nature of mineral isotope analysis, and substantial progress has been made in the field. New applications for stable isotopes and new analytical methods have been introduced recently. However, limitations to the approach and methodological problems remain to be resolved. This review describes early work in the field and discusses the advantages and disadvantages of stable isotope tracers and of the various methods of analysis. Information discovered with stable isotopes is reviewed, and probable future applications are discussed.69 references.

  15. Stable carbon isotope ratio of polycyclic aromatic hydrocarbons (PAHs) in the environment: validation of isolation and stable carbon isotope analysis methods

    E-print Network

    Kim, Moon Koo

    2004-11-15

    to confirm compositional and stable isotopic integrity during purification and stable isotopic analysis. To confirm the utility of the purification and isotope analysis methods, various environmental samples from marine, land and lacustrine environments were...

  16. Isotopic abundance in atom trap trace analysis

    DOEpatents

    Lu, Zheng-Tian; Hu, Shiu-Ming; Jiang, Wei; Mueller, Peter

    2014-03-18

    A method and system for detecting ratios and amounts of isotopes of noble gases. The method and system is constructed to be able to measure noble gas isotopes in water and ice, which helps reveal the geological age of the samples and understand their movements. The method and system uses a combination of a cooled discharge source, a beam collimator, a beam slower and magneto-optic trap with a laser to apply resonance frequency energy to the noble gas to be quenched and detected.

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

    PubMed Central

    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

  18. Micronutrient Cadmium in the Oceans, Distribution and Stable Isotope Fractionation

    NASA Astrophysics Data System (ADS)

    Abouchami, W.; Galer, S. J.; Feldmann, H.; Andreae, M. O.; de Baar, H.; Middag, R.; Klunder, M.; Laan, P.

    2012-12-01

    Recent breakthroughs in ultra-clean seawater sampling, analytical instrumentation and chemical separation of trace metals have led to significant improvement in both sensitivity and accuracy of concentration measurements of some key bio-limiting metals such as Zn, Cd and Fe. Stable isotope fractionations of these transition metal elements have added a further new dimension to our understanding of the marine biogeochemical cycling of trace nutrients. Improving our understanding of the latter is essential for assessing the impact of climate changes on the global carbon cycle, given the control of oceanic nutrient inventories on the efficiency of the "biological pump" and hence, its strength in regulating the sequestration of atmospheric CO2. The first reliable vertical distribution profiles of trace metal element cadmium (Cd) in the oceans [1, 2] showed a correlation with the major nutrient phosphate. This apparent involvement of Cd in the ocean biological cycle was unexpected, as Cd was known to be toxic, notably at high Cd abundance where it interferes with the true biological function of zinc (Zn), due to their similar chemistry. The novel ability to measure accurately the stable isotope fractionation of Cd in seawater may now help unravel the apparent role of Cd in the ocean biological cycle, akin to the classical breakthroughs and numerous applications of the ratio 13C/12C for understanding the ocean carbon cycle. We have examined the distribution of Cd concentration and isotope ratios in depth profiles from the High Nutrients Low Chlorophyll (HNLC) Southern Ocean, collected within the framework of the international GEOTRACES program. The first surface water transect along the Greenwich Meridian in the Southern Ocean revealed a strong meridional isotope gradient and two major biogeochemical provinces with distinctive Cd isotope fractionation factors, apparently related to phytoplankton community compositions and cellular uptake mechanisms [3]. Here we focus on the vertical distribution of Cd concentration and isotope ratios in the water column, as these reflect the combined effects of physical, chemical, and biological processes that control the export of carbon to the deep ocean. Cadmium concentration depth profiles show typical nutrient-like distributions with differences in the Cd-maxima depths, consistent with those of phosphate and reveal changes in the depth of re-mineralization of Cd and PO4 across the Antarctic. A strong surface-to-depth isotope gradient is seen in all profiles with high ?112/110Cd values in the mixed layer of up to +4.5 and low values of about +1.2, identifying deep Antarctic waters with a Cd-light isotope signature. The depth zone of maximum changes in Cd concentration and ?112/110Cd values coincide with that of the apparent oxygen utilization, a tracer of carbon export, demonstrating the role of Cd as an important nutrient for marine ecosystems. Examination of property-property co-variations provide new insights into the cycling of Cd and other trace metals which will be discussed, with emphasis on the significance of the global oceanic Cd-phosphate correlation and use and pitfalls of Cd isotopes as tracer of past changes in the strength of the biological carbon pump and the thermohaline circulation. [1] Boyle et al. (1976), Nature 263, 42-44. [2] Bruland (1980), EPSL, 47, 176-198. [3] Abouchami et al. (2011), EPSL 305, 83-91.

  19. Stable isotopes in late Pennsylvanian brachiopods: stratigraphic and paleoenvironmental implications

    E-print Network

    Zhang, Chuanlun

    1989-01-01

    composition. Of the four selected species, Crurithyris pianoconvexa and Composita subtiiita provide the most complete isotope stratigraphies for the units studied. The oxygen isotopic compositions of Crurithyris from the three units differ only slightly... are abundant and diagnostic characterizes the shallow marine environment; the fusulinid zone denotes intermediate depths because of abundant occurrence of fusulinids at this depth; the ammonoid zone represents deeper water in an open marine environment...

  20. Compound specific stable isotope analysis vs. bulk stable isotope analysis of agricultural food products

    NASA Astrophysics Data System (ADS)

    Psomiadis, David; Horváth, Balázs; Nehlich, Olaf; Bodiselitsch, Bernd

    2015-04-01

    The bulk analysis of stable isotopes (carbon, nitrogen, sulphur, oxygen and hydrogen) from food staples is a common tool for inferring origin and/or fraud of food products. Many studies have shown that bulk isotope analyses of agricultural products are able to separate large geographical areas of food origin. However, in micro-localities (regions, districts, and small ranges) these general applications fail in precision and discriminative power. The application of compound specific analysis of specific components of food products helps to increase the precision of established models. Compound groups like fatty acids (FAMEs), vitamins or amino acids can help to add further detailed information on physiological pathways and local conditions (micro-climate, soil, water availability) and therefore might add further information for the separation of micro-localities. In this study we are aiming to demonstrate the power and surplus of information of compound specific isotope analysis in comparison to bulk analysis of agricultural products (e.g. olive oil, cereal crops or similar products) and discuss the advantages and disadvantages of such (labor intense) analysis methods. Here we want to identify tools for further detailed analysis of specific compounds with high powers of region separation for better prediction models.

  1. STABLE ISOTOPIC RESPONSE TO THE LATE EOCENE EXTRATERRESTRIAL IMPACT EVENTS

    E-print Network

    STABLE ISOTOPIC RESPONSE TO THE LATE EOCENE EXTRATERRESTRIAL IMPACT EVENTS by AIMEE E PUSZ A thesis to the Late Eocene Extraterrestrial Impact Events by AIMEE ELIZABETH PUSZ Thesis Director: Dr. Kenneth G

  2. BIODEGRADATION OF FLUORANTHENE AS MONITORED USING STABLE CARBON ISOTOPES

    EPA Science Inventory

    The measurement of stable isotope ratios of carbon (d13C values) was investigated as a viable technique to monitor the intrinsic bioremediation of polycyclic aromatic hydrocarbons (PAHs). Biometer-flask experiments were conducted in which the bacterium, Sphingomonas paucimobilis,...

  3. Isotope-abundance variations of selected elements (IUPAC technical report)

    USGS Publications Warehouse

    Coplen, T.B.; Böhlke, J.K.; De Bievre, P.; Ding, T.; Holden, N.E.; Hopple, J.A.; Krouse, H.R.; Lamberty, A.; Peiser, H.S.; Revesz, K.; Rieder, S.E.; Rosman, K.J.R.; Roth, E.; Taylor, P.D.P.; Vocke, R.D., Jr.; Xiao, Y.K.

    2002-01-01

    Documented variations in the isotopic compositions of some chemical elements are responsible for expanded uncertainties in the standard atomic weights published by the Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry. This report summarizes reported variations in the isotopic compositions of 20 elements that are due to physical and chemical fractionation processes (not due to radioactive decay) and their effects on the standard atomic-weight uncertainties. For 11 of those elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine, copper, and selenium), standard atomic-weight uncertainties have been assigned values that are substantially larger than analytical uncertainties because of common isotope-abundance variations in materials of natural terrestrial origin. For 2 elements (chromium and thallium), recently reported isotope-abundance variations potentially are large enough to result in future expansion of their atomic-weight uncertainties. For 7 elements (magnesium, calcium, iron, zinc, molybdenum, palladium, and tellurium), documented isotope variations in materials of natural terrestrial origin are too small to have a significant effect on their standard atomic-weight uncertainties. This compilation indicates the extent to which the atomic weight of an element in a given material may differ from the standard atomic weight of the element. For most elements given above, data are graphically illustrated by a diagram in which the materials are specified in the ordinate and the compositional ranges are plotted along the abscissa in scales of (1) atomic weight, (2) mole fraction of a selected isotope, and (3) delta value of a selected isotope ratio.

  4. Stable isotopes in precipitation in the Asian monsoon region

    Microsoft Academic Search

    M. Vuille; M. Werner; R. S. Bradley; F. Keimig

    2005-01-01

    The influence of the Asian monsoon on the delta18O composition of precipitation is investigated on the basis of the ECHAM-4 Atmospheric General Circulation Model (AGCM), fitted with stable isotopic tracers. The model is forced with prescribed sea surface temperatures (SST) over the last few decades of the 20th century. The simulated climate and climate-stable isotope relationships are validated with observational

  5. Environmental information stored in otoliths: insights from stable isotopes

    Microsoft Academic Search

    R. L. Radtke; P. Lenz; W. Showers; E. Moksness

    1996-01-01

    The present study compares the stable oxygen-and carbon-isotope ratios (180:16O;13C:12C) in the otoliths of Atlantic cod,Gadus morhua, with those expected at equilibrium with seawater. Otoliths from juveniles reared for a 3 mo period under controlled conditions indicate that otoliths are formed in isotopic disequilibrium with seawater. This is probably due to positive metabolic fractionating of the heavier isotopes. This “vital

  6. Equilibrium stable-isotope fractionation of thallium and mercury

    Microsoft Academic Search

    E. A. Schauble

    2005-01-01

    In this study first-principles quantum mechanical and empirical force-field models are used to estimate equilibrium mass-dependent isotopic fractionations among a variety of thallium and mercury compounds. High-precision MC-ICP-MS measurements have recently uncovered evidence of stable isotope fractionation for many elements, including 2-40\\/00 variability in the isotopic compositions of thallium[1] (atomic no. 81) and mercury[2] (atomic no. 80). The observed thallium-

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

    SciTech Connect

    Flayler, K.A. (comp.)

    1987-12-15

    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.

  8. Stable isotope sales: Mound customer and shipment summaries, FY 1986

    SciTech Connect

    Kramer, L.R. (ed.); Flayler, K.A. (comp.)

    1988-05-20

    A listing is given of Mound's sales of stable isotopes of noble gases, carbon, oxygen, nitrogen, chlorine, and sulfur for fiscal year 1986. Purchasers are listed alphabetically and are divided into domestic and foreign groups. Cross-reference indexes by location and by isotope are included for all customers. 3 tabs.

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

    EPA Science Inventory

    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...

  10. Review: Stable oxygen isotope composition of plant tissue: a review

    Microsoft Academic Search

    Margaret M. Barbour

    2007-01-01

    With the development of rapid measurement techniques, stable oxygen isotope analysis of plant tissue is poised to become an important tool in plant physiological, ecological, paleoclimatic and forensic studies. Recent advances in mechanistic understanding have led to the improvement of process-based models that accurately predict variability in the oxygen isotope composition of plant organic material (?18Op). ?18Op has been shown

  11. Carbon Stable Isotopes as Indicators of Coastal Eutrophication

    EPA Science Inventory

    Coastal ecologists and managers have frequently used nitrogen stable isotopes (d15N) to trace and monitor anthropogenic nitrogen (N) in coastal ecosystems. However, the interpretation of d15N data can often be challenging, if not confounding, as the isotope values fractionate su...

  12. Equations for Lipid Normalization of Carbon Stable Isotope Ratios in Aquatic Bird Eggs

    PubMed Central

    Elliott, Kyle H.; Davis, Mikaela; Elliott, John E.

    2014-01-01

    Stable isotope ratios are biogeochemical tracers that can be used to determine the source of nutrients and contaminants in avian eggs. However, the interpretation of stable carbon ratios in lipid-rich eggs is complicated because 13C is depleted in lipids. Variation in 13C abundance can therefore be obscured by variation in percent lipids. Past attempts to establish an algebraic equation to correct carbon isotope ratios for lipid content in eggs have been unsuccessful, possibly because they relied partly on data from coastal or migratory species that may obtain egg lipids from different habitats than egg protein. We measured carbon, nitrogen and sulphur stable isotope ratios in 175 eggs from eight species of aquatic birds. Carbon, nitrogen and sulphur isotopes were enriched in lipid-extracted egg samples compared with non extracted egg samples. A logarithmic equation using the C?N ratio and carbon isotope ratio from the non extracted egg tissue calculated 90% of the lipid-extracted carbon isotope ratios within ±0.5‰. Calculating separate equations for eggs laid by species in different habitats (pelagic, offshore and terrestrial-influenced) improved the fit. A logarithmic equation, rather than a linear equation as often used for muscle, was necessary to accurately correct for lipid content because the relatively high lipid content of eggs compared with muscle meant that a linear relationship did not accurately approximate the relationship between percent lipids and the C?N ratio. Because lipid extraction alters sulphur and nitrogen isotope ratios (and cannot be corrected algebraically), we suggest that isotopic measurement on bulk tissue followed by algebraic lipid normalization of carbon stable isotope ratio is often a good solution for homogenated eggs, at least when it is not possible to complete separate chemical analyses for each isotope. PMID:24465384

  13. Stable isotope variations in Banded Iron Formations

    Microsoft Academic Search

    T. A. Jr. Abrajano; B. D. Holt

    1991-01-01

    In spite of the significant amount of work already reported in the scientific literature, many aspects of the origin of Banded Iron Formations (BIF) remain enigmatic. The authors demonstrate that mineralogic microbanding in BIF is accompanied by autocorrelated isotopic microbanding of organic carbon and carbonate carbon and oxygen. They propose that these isotopic patterns formed as a result of episodic

  14. Tracing Food Webs with Stable Hydrogen Isotopes

    Microsoft Academic Search

    Marilyn F. Estep; Halina Dabrowski

    1980-01-01

    The hydrogen isotopic content of an animal's food, not water, determines that animal's hydrogen isotopic content. Liver and muscle tissue from mice reared on a diet such that the ratio of deuterium to hydrogen (D\\/H) of their food and water was kept constant, have the same average D\\/H ratio as the food source. In a simple, natural population of snails

  15. Stable isotope geochemistry of deep sea cherts

    Microsoft Academic Search

    Yehoshua Kolodny; Samuel Epstein

    1976-01-01

    Seventy four samples of DSDP recovered cherts of Jurassic to Miocene age from varying locations, and 27 samples of on-land exposed cherts were analyzed for the isotopic composition of their oxygen and hydrogen. These studies were accompanied by mineralogical analyses and some isotopic analyses of the coexisting carbonates. 18 O of chert ranges between 27 and 39%. relative to SMOW,

  16. Stable isotope ecology in the Omo-Turkana Basin.

    PubMed

    Cerling, Thure E; Levin, Naomi E; Passey, Benjamin H

    2011-01-01

    Stable isotopes provide an independent assessment of paleoenvironments in the Omo-Turkana Basin. Stable isotopes track the flow of oxygen and carbon through ecosystems and accordingly are not directly related to changes in mammalian faunal composition or sedimentology. Therefore, isotope studies give insight into the paleoenvironmental conditions in which human evolutionary trends have been recorded. The development of stable isotopes as indicators of continental environmental conditions has proceeded in parallel with questions about the conditions of human environment. What was the vegetation? How hot was it? How dry? What were the diets of animals living among early humans? And most persistently, how important were "savannas" to early hominids? In this review, we take the opportunity to provide extensive background on the use of isotopes in anthropological sites. The application of stable isotope ecology to anthropological sites in the Turkana Basin has a long history, but in many ways the Omo-Turkana Basin has been a proving ground for the development of new proxy methods for understanding tropical terrestrial environments in the Neogene and Quaternary. For that reason, we also describe some of the fundamental aspects of isotope ecology that developed outside the field of paleoanthropology. PMID:22170692

  17. Stable Isotope Ratios as Biomarkers of Diet for Health Research.

    PubMed

    O'Brien, Diane M

    2015-07-17

    Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment. Consequently, there is a pressing need for more objective biomarkers of diet for use in health research. The stable isotope ratios of light elements are a promising set of candidate biomarkers because they vary naturally and reproducibly among foods, and those variations are captured in molecules and tissues with high fidelity. Recent studies have identified valid isotopic measures of short- and long-term sugar intake, meat intake, and fish intake in specific populations. These studies provide a strong foundation for validating stable isotopic biomarkers in the general US population. Approaches to improve specificity for specific foods are needed; for example, by modeling intake using multiple stable isotope ratios or by isolating and measuring specific molecules linked to foods of interest. PMID:26048703

  18. Fractionation of metal stable isotopes by higher plants

    USGS Publications Warehouse

    Von Blanckenburg, F.; Von Wiren, N.; Guelke, M.; Weiss, D.J.; Bullen, T.D.

    2009-01-01

    Higher plants induce chemical reactions in the rhizosphere, facilitating metal uptake by roots. Fractionation of the isotopes in nutrients such as calcium, iron, magnesium, and zinc produces a stable isotope composition in the plants that generally differs from that of the growth medium. Isotope fractionation also occurs during transport of the metals within most plants, but its extent depends on plant species and on the metal, in particular, on the metal's redox state and what ligand it is bound to. The metal stable isotope variations observed in plants create an isotope signature of life at the Earth's surface, contributing substantially to our understanding of metal cycling processes in the environment and in individual organisms.

  19. Stable isotope paleoaltimetry of the Mount Everest region

    NASA Astrophysics Data System (ADS)

    Gebelin, A.; Mulch, A.; Teyssier, C.; Jessup, M. J.; Law, R. D.; Brunel, M.

    2012-12-01

    Long-term climatic evolution and atmospheric circulation patterns are influenced to a first order by the topography of the largest mountain ranges. Reconstructing the Neogene elevation history of the Mount Everest region is of particular interest for understanding the tectonic history of the Himalaya-Tibet orogen as well as global scale atmospheric circulation and biotic changes through time. Stable isotope paleoaltimetry uses the isotopic lapse rate of precipitations preserved in the near-surface record. In the absence of surface deposits such as paleosols, volcanic ashes, or lacustrine limestone that record the stable isotopic composition of early to mid-Miocene water preserved in the highly erosive Himalayan range, we conduct stable-isotope paleoaltimetry based on the hydrogen isotopic composition (?D) of hydrous minerals that crystallized in the South Tibetan detachment (STD) shear zone at ~17 Ma. For paleoaltimetry reconstruction we compare stable isotope records from the STD mylonitic footwall to age-equivalent oxygen isotope ratios (?18O) measured within pedogenic carbonate from Siwalik foreland paleosols that developed near Miocene sea level. The relative differences between meteoric water compositions in the foreland basin and the ?18Owater calculated from the hydrogen isotope composition of syntectonic minerals suggest that by ~17 Ma the central Himalaya was at an elevation similar to what it is today, and that a rain shadow likely existed at that time. Our results demonstrate the power of shear-zone based paleoaltimetry in eroded mountain belts, call for caution in interpreting basin-based stable isotope paleoaltimetry in the rain shadow of the mid-Miocene Himalayan range and suggest that strengthening of the South Asian monsoon may have occurred in early to mid-Miocene, earlier than previously thought.

  20. UNiquant, a Program for Quantitative Proteomics Analysis Using Stable Isotope Labeling

    SciTech Connect

    Huang, Xin; Tolmachev, Aleksey V.; Shen, Yulei; Liu, Miao; Huang, Lin; Zhang, Zhixin; Anderson, Gordon A.; Smith, Richard D.; Chan, Wing C.; Hinrichs, Steven; Fu, Kai; Ding, Shi-Jian

    2011-03-04

    We present UNiquant, a new software program for analyzing stable isotope labeling (SIL) based quantitative proteomics data. UNiquant surpassed the performance of two other platforms, MaxQuant and Mascot Distiller, using complex proteome mixtures having either known or unknown heavy/light ratios. UNiquant is compatible with a broad spectrum of search engines and SIL methods, providing outstanding peptide pair identification and accurate measurement of the relative peptide/protein abundance.

  1. Tracing food webs with stable hydrogen isotopes.

    PubMed

    Estep, M F; Dabrowski, H

    1980-09-26

    The hydrogen isotopic content of an animal's food, not water, determines that animal's hydrogen isotopic content. Liver and muscle tissue from mice reared on a diet such that the ratio of deuterium to hydrogen (DIH) of their food and water was kept constant, have the same average D/H ratio as the food source. In a simple, natural population of snails and their possible algal diets, Littorina obtusata (northern Atlantic intertidal snails that feed almost exclusively on the brown alga Fucus vesiculosus) has the same D/H ratio as Fucus vesiculosis and not that of the other algae available to the snails. PMID:17745967

  2. Tritium and stable isotopes of magmatic waters

    Microsoft Academic Search

    F. Goff; G. M. McMurtry

    2000-01-01

    To investigate the isotopic composition and age of water in volcanic gases and magmas, we analyzed samples from 11 active volcanoes ranging in composition from tholeiitic basalt to rhyolite: Mount St. Helens (USA), Kilauea (USA), Pacaya (Guatemala), Galeras (Colombia), Satsuma Iwo-Jima (Japan), Sierra Negra and Alcedo (Ecuador), Vulcano (Italy), Par??cutin (Mexico), Kudryavy (Russia), and White Island (New Zealand). Tritium at

  3. The Abundance and Isotopic Composition of Hg in Extraterrestrial Materials

    NASA Technical Reports Server (NTRS)

    Lauretta, D. S.

    2004-01-01

    During the past three year grant period we made excellent progress in our study of the abundances and isotopic compositions of Hg and other volatile trace elements in extraterrestrial materials. As part of my startup package I received funds to construct a state-of-the-art experimental facility to study gas-solid reaction kinetics. Much of our effort was spent developing the methodology to measure the abundance and isotopic composition of Hg at ultratrace levels in solid materials. In our first study, the abundance and isotopic composition of Hg was determined in bulk samples of the Murchison (CM) and Allende (CV) carbonaceous chondrites. We have continued our study of mercury in primitive meteorites and expanded the suite of meteorites to include other members of the CM and CV chondrite group as well as CI and CO chondrites. Samples of the CI chondrite Orgueil, the CM chondrites Murray, Nogoya, and Cold Bokkeveld, the CO chondrites Kainsaz, Omans, and Isna, and the CV chondrites Vigarano, Mokoia, and Grosnaja were tested. We have developed a thermal analysis ICP-MS technique and applied it to the study of a suite of thermally labile elements (Zn, As, Se, Cd, In, Sn, Sb, Te, Hg, Au, Tl, Pb, and Bi) in geologic materials as well.

  4. Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance

    NASA Technical Reports Server (NTRS)

    Mahaffy, P.; Mauersberger, K.

    1993-01-01

    The Viking gas chromatograph mass spectrometer experiment provided significant data on the atmospheric composition at the surface of Mars, including measurements of several isotope ratios. However, the limited dynamic range of this mass spectrometer resulted in marginal measurements for the important Kr and Xe isotopic abundance. The Xe-129 to Xe-132 ratio was measured with an uncertainty of 70%, but none of the other isotope ratios for these species were obtained. Accurate measurement of the Xe and Kr isotopic abundance in this atmosphere provides an important data point in testing theories of planetary formation and atmospheric evolution. The measurement is also essential for a stringent test for the Martian origin of the SNC meteorites, since the Kr and Xe fractionation pattern seen in gas trapped in glassy nodules of an SNC (EETA 79001) is unlike any other known solar system resevoir. Current flight mass spectrometer designs combined with the new technology of a high-performance vacuum pumping system show promise for a substantial increase in gas throughput and the dynamic range required to accurately measure these trace species. Various aspects of this new technology are discussed.

  5. Stable carbon and sulfur isotopes as records of the early biosphere

    NASA Technical Reports Server (NTRS)

    Desmarais, David J.

    1989-01-01

    The abundance ratios of the stable isotopes of light elements such as carbon and sulfur can differ between various naturally-occurring chemical compounds. If coexisting compounds have achieved mutual chemical and isotopic equilibrium, then the relative isotopic composition can record the conditions at which equilibrium was last maintained. If coexisting chemical compounds indeed formed simultaneously but had not achieved mutual equilibrium, then their relative isotopic compositions often reflect the conditions and mechanisms associated with the kinetically controlled reactions responsible for their production. In the context of Mars, the stable isotopic compositions of various minerals might record not only the earlier environmental conditions of the planet, but also whether or not the chemistry of life ever occurred there. Two major geochemical reservoirs occur in Earth's crust, both for carbon and sulfur. In rocks formed in low temperature sedimentary environments, the oxidized forms of these elements tend to be enriched in the isotope having the larger mass, relative to the reduced forms. In sediments where the organics and sulfides were formed by biological processes, these isotopic contrasts were caused by the processes of biological CO2 fixation and dissimilatory sulfate reduction. Such isotopic contrasts between oxidized and reduced forms of carbon and sulfur are permitted by thermodynamics at ambient temperatures. However, nonbiological chemical reactions associated with the production of organic matter and the reduction of organics and sulfides are extremely slow at ambient temperatures. Thus the synthesis of organics and sulfides under ambient conditions illustrates life's profound role as a chemical catalyst that has altered the chemistry of Earth's crust. Because the stable isotopes of carbon and sulfur can reflect their chemistry, they are useful probes of the Martian surface.

  6. From birds to butterflies: animal movement patterns and stable isotopes.

    PubMed

    Rubenstein, Dustin R; Hobson, Keith A

    2004-05-01

    Establishing patterns of movement of wild animals is crucial for our understanding of their ecology, life history and behavior, and is a prerequisite for their effective conservation. Advances in the use of stable isotope markers make it possible to track a diversity of animal species in a variety of habitats. This approach is revolutionizing the way in which we make connections between phases of the annual cycle of migratory animals. However, researchers must exercise care in their application of isotopic methods. Here, we review stable isotope patterns in nature and discuss recent tracking applications in a range of taxa. To aid in the interpretation and design of effective and insightful isotope movement studies, we discuss a series of key issues and assumptions. This exciting field will advance rapidly if researchers consider these aspects of study design and interpretation carefully. PMID:16701265

  7. Using stable isotopes of water to infer wetland hydrological dynamics

    NASA Astrophysics Data System (ADS)

    Clay, A.; Bradley, C.; Gerrard, A. J.; Leng, M. J.

    This paper considers the potential of oxygen and hydrogen isotope ratios to identify spatial and temporal changes in the water source of a lowland headwater wetland situated adjacent to the River Tern in Shropshire, UK. Stable isotope composition (d18O) of end-members varied between -7.5 and -8.0‰ for groundwater, -7.3 and -8.5‰ for river-water and -4.5 and -8.0‰ for precipitation. Water samples were extracted from six nests each comprising three porous cup samplers at depths of 0.2 m, 0.5 m and 1.0 m between June 2000 and October 2001, and their isotope compositions determined. Groundwater appears to be the main source of water to the wetland, but stable isotope ratios enable seasonal variations in the contribution of precipitation to be determined, and indicate the extent of precipitation storage within the wetland.

  8. Stable platinum isotope measurements in presolar nanodiamonds by TEAMS

    PubMed Central

    Wallner, A.; Melber, K.; Merchel, S.; Ott, U.; Forstner, O.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.

    2013-01-01

    Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction. PMID:23565017

  9. Evaluation and Integration of Environmental Stress Using Stable Isotopes

    Microsoft Academic Search

    H. Griffiths

    Recent developments in the use of stable isotopes are set in the context of advances in theory and analytical procedures,\\u000a with emphasis on potential applications for the future. Starting from initial requirements for biological markers which would\\u000a allow the deconvolution of past climatic conditions, a mechanistic framework has been developed for the isotopes of carbon\\u000a (?13C), oxygen (?18O) and hydrogen

  10. Stable carbon isotope fractionation during aerobic biodegradation of chlorinated ethenes

    Microsoft Academic Search

    Kung-Hui Chu; Shaily Mahendra; Donald L. Song; Mark E. Conrad; Lisa Alvarez-Cohen

    2003-01-01

    Stable isotope analysis is recognized as a powerful tool for monitoring, assessing, and validating in-situ bioremediation processes. In this study, kinetic carbon isotope fractionation factors () associated with the aerobic biodegradation of vinyl chloride (VC), cis-1,2-dichloroethylene (cDCE), and trichloroethylene (TCE) were examined. Of the three solvents, the largest fractionation effects were observed for biodegradation of VC. Both metabolic and cometabolic

  11. Magnesium stable isotope fractionation in marine biogenic calcite and aragonite

    Microsoft Academic Search

    F. Wombacher; A. Eisenhauer; F. Böhm; N. Gussone; M. Regenberg; W.-Chr. Dullo; A. Rüggeberg

    2011-01-01

    This survey of magnesium stable isotope compositions in marine biogenic aragonite and calcite includes samples from corals, sclerosponges, benthic porcelaneous and planktonic perforate foraminifera, coccolith oozes, red algae, and an echinoid and brachiopod test. The analyses were carried out using MC-ICP-MS with an external repeatability of ±0.22‰ (2SD for ?26Mg; n=37), obtained from a coral reference sample (JCp-1).Magnesium isotope fractionation

  12. Stable isotope composition of the meteoric precipitation in Croatia.

    PubMed

    Hunjak, Tamara; Lutz, Hans O; Roller-Lutz, Zvjezdana

    2013-01-01

    The precipitation is the input into the water system. Its stable isotope composition has to be known for the proper use and management of water resources. Croatia is not well represented in the Global Network of Isotopes in Precipitation (GNIP) database, and the geomorphology of the country causes specific local conditions. Therefore, at the Stable Isotope Laboratory (SILab), Rijeka, we monitor the stable isotope composition (?(18)O, ?(2)H) of precipitation. Since ?(18)O and ?(2)H are well correlated, we concentrate the discussion on the ?(18)O distribution. Together with GNIP, our database contains 40 stations in Croatia and in the neighbouring countries. Their different latitudes, longitudes and altitudes give information of great detail, including the influence of the topographic structure on the precipitation in the south-eastern part of Europe, as well as the complex interplay of the different climate conditions in the area. Within a few hundred kilometres, the stable isotope values display a significant change from the maritime character in the south (mean ?(18)O around-6 to-8‰) to the continental behaviour in the north (mean ?(18)O around-8 to-11‰). Depending on the location, the mean ?(18)O values vary with altitude at a rate of approximately-0.2‰/100 m and-0.4‰/100 m, respectively. Also the deuterium excess has been found to depend on location and altitude. The data are being used to construct a ?(18)O map for the entire area. PMID:23937110

  13. Abundance, distribution, and isotopic composition of particulate black carbon in the northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Yang, Weifeng; Guo, Laodong

    2014-11-01

    There exists increasing evidence supporting the important role of black carbon in global carbon cycles. Particulate black carbon (PBC) is allochthonous and has distinct reactivities compared to the bulk particulate organic carbon (tot-POC) in marine environments. However, the abundance, geochemical behavior of PBC and its importance in oceanic carbon budget remain poorly understood. Here we report the abundance, distribution, and stable isotopic signatures of BC derived from the chemo-thermal oxidation (CTO-375) method (BCCTO) in the Gulf of Mexico. Our results show that BCCTO abundance decreased from shelf to basin, and more than a half of riverine BCCTO could be removed over the shelf. Moreover, BCCTO is much more refractory compared to the tot-POC and has ?13C values lower than those of BC-excluded POC. These results highlight the significance of PBC in marine carbon cycles and potentially suggest the need for a new end-member term in quantifying POC sources in the ocean.

  14. Stable isotopic composition of water vapor in the tropics

    NASA Astrophysics Data System (ADS)

    Lawrence, James Robert; Gedzelman, Stanley David; Dexheimer, Darielle; Cho, Hye-Khung; Carrie, Gordon D.; Gasparini, Robert; Anderson, Casey R.; Bowman, Kenneth P.; Biggerstaff, Mike I.

    2004-03-01

    Water vapor samples collected during tropical field experiments at Puerto Escondido, Mexico, near Kwajalein (KWAJEX), and near Key West, Florida (CAMEX 4), were analyzed for their stable isotope contents, 1H218O:1H216O and 2H1H16O:1H216O. Highest ?18O values approached isotopic equilibrium with seawater during quiescent weather or in regions of isolated or disorganized convection. Lowest ?18O values occurred in or downwind from regions of organized mesoscale weather disturbances and ranged as low as 15‰ below isotopic equilibrium with seawater. The mean ?18O value of vapor over the sea surface therefore decreases as storm activity and organization increases.

  15. The abundances of elements and isotopes in the solar wind

    SciTech Connect

    Gloeckler, G. (The Johns Hopkins University, Applied Physics Laboratory, Laurel, Maryland 20707, USA (USA)); Geiss, J. (Physikalisches Institut, University of Bern (Switzerland))

    1989-03-01

    Solar wind abundances have now been measured for eleven elements and the isotopes of the noble gases. The composition of all elements up to and including Ni, as well as most of their isotopes, should become known when new high-mass-resolution solar wind spectrometers are launched in the next decade. Aside from solar wind protons and alpha particles, which have been studied extensively since the 1960's, our information for heavier elements is limited. Nevertheless, two effects stand out. First is the enrichment of abundances of elements with low first ionizaiton potential (FIP), most likely the combined result of (a) an atom-ion separation process in the upper chromosphere, and (b) a marginal coupling of low-charge-state heavy ions to protons and alphas during the acceleration of the solar wind. Second, there is variability in the solar wind composition over a whole range of time scales. Recent measurements carried out in the Earth's magnetosheath during times that included high-speed coronal-hole-associated flows indicate a significantly lower overabundance of low FIP elements. Given the fact that the He/H ratio is remarkably constant in the coronal hole solar wind, this result suggests that both enrichment and variability are reduced in such flows. Studies by the ULYSSES spacecraft of the characteristics and composition of the least complicated solar wind, i.e., the flow emanating from the polar coronal holes, should significantly increase our understanding of coronal processes and solar wind acceleration. By combining these studies with measurements of the complete elemental and isotopic composition of the solar wind, we will be able to derive solar abundances for elements and isotopes that otherwise are poorly known.

  16. Continental-Scale Stable Isotope Measurements at NEON to Address Ecological Processes Across Systems

    NASA Astrophysics Data System (ADS)

    Luo, H.; Goodman, K. J.; Hinckley, E. S.; West, J. B.; Williams, D. G.; Bowen, G. J.

    2013-12-01

    The National Ecological Observatory Network (NEON) is a national-scale research platform. The overarching goal of NEON is to enable understanding and forecasting of the impacts of climate change, land use change, and invasive species on aspects of continental-scale ecology (such as biodiversity, biogeochemistry, infectious diseases, ecohydrology, etc.). NEON focuses explicitly on questions that relate to grand challenges in environmental science, are relevant to large regions, and would otherwise be very difficult to address with traditional ecological approaches. The use of stable isotope approaches in ecological research has grown steadily during the last two decades. Stable isotopes at natural abundances in the environment trace and integrate the interaction between abiotic and biotic components across temporal and spatial scales. In this poster, we will present the NEON data products that incorporate stable isotope measurements in atmospheric, terrestrial, and aquatic ecosystems in North America. We further outline current questions in the natural sciences community and how these data products can be used to address continental-scale ecological questions, such as the ecological impacts of climate change, terrestrial-aquatic system linkages, land-atmosphere exchange, landscape ecohydrological processes, and linking biogeochemical cycles across systems. Specifically, we focus on the use of stable isotopes to evaluate water availability and residence times in terrestrial systems, as well as nutrient sources to terrestrial systems, and cycling across ecosystem boundaries.

  17. Changes in ? 13 C stable isotopes in multiple tissues of insect predators fed isotopically distinct prey

    Microsoft Academic Search

    Claudio Gratton; Andrew E. Forbes

    2006-01-01

    Traditionally, researchers have used measurements of carbon stable isotopes to infer the composition of consumers’ diets.\\u000a However, since consumer’s tissues may process carbon isotopes differently, particularly following a diet shift, it is possible\\u000a to use measurements of carbon isotopes in multiple tissues to determine not only the composition of an individual’s diet,\\u000a but also the temporal dynamics thereof. This study

  18. Platinum stable isotopes in ferromanganese crust and nodules

    NASA Astrophysics Data System (ADS)

    Corcoran, Loretta; Seward, Terry; Handler, Monica R.

    2015-04-01

    Hydrogenetic ferromanganese (Fe-Mn) crust and nodules are slow-growing chemical sediments that form by direct precipitation from seawater, resulting in a record of changing seawater chemistry. These sediments are the primary sink for platinum in the modern oxic marine environment, hosting well-documented enrichments over other platinum-group elements (PGEs): the Pt anomaly [1]. Platinum is a non-bio-essential, highly siderophile, transition metal with six stable isotopes (190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt) with several oxidation states (Pt0, Pt2+ and Pt4+). Platinum is generally considered to exist in the hydrosphere as Pt2+ although its behaviour in the marine environment is poorly constrained, and Pt4+may also be present. Variations in ocean redox state, together with changes in source fluxes to the oceans, may therefore lead to small variations (< ±1) in the stable isotopic composition of marine platinum, raising the potential of adding platinum to the growing arsenal of paleoceanographic tracers. A method has been developed to measure the platinum isotopic composition using double spike MC-ICPMS analysis [2]and applied to a global suite of modern Fe-Mn crust and nodules. Combining synchrotron XAFS analyses of platinum adsorbed onto Fe-Mn oxide and oxyhydroxide surfaces to determine oxidation state and bonding environment, with platinum stable isotopic measurements allowing us to evaluate both platinum incorporation onto these sediments and the associated degree of platinum isotopic fractionation. Leaching experiments conducted on platinum rich terrestrial materials underwent platinum stable isotopic measurement as an analogue for the Pt isotopic fractionation associated with continental weathering. [1] Hodge, V.F. et al. (1985) Earth and Planetary Science Letters, 72, 158-162. [2] Creech, J. et al. (2013) Journal of Analytical Atomic Spectrometry, 28. 853-865.

  19. Stable isotopes determination in some Romanian wines.

    PubMed

    Magdas, Dana Alina; Cuna, Stela; Cristea, Gabriela; Ionete, Roxana Elena; Costinel, Diana

    2012-06-01

    This paper presents a study concerning the isotopic fingerprint ((18)O and (13)C) of some wines prepared from relevant Romanian grape varieties (e.g. Feteasca Alba (FA), Feteasca Regala (FR) and Cabernet Sauvignon (CS)) obtained in different vintage years (2002, 2003, 2004, 2007 and 2008). These wines were obtained from different vineyards having a significant role in the wine market: Cotesti, Tohani, Stefanesti, Aiud, Cotnari, Bucium, Murfatlar, Bujoru, Dragasani and Valea Calugareasca. Several observations related to the dependence of isotope ratios on geographical origin and climatic conditions were drawn. The authentic wines obtained from the FA grape variety from six different vineyards showed ?(18)O values in the range of+3.28 (Cotesti region - 45 °38'N/27 °04'E) to-2.60 ‰ (Aiud region - 46 °19'N/23 °45'E). The ?(13)C values were very similar for all the samples with an average of about-26 ‰. The difference between the ?(18)O values was due to the different climatic zones, which have an influence on the ?(18)O values of wine water. For the wine variety CS obtained from the Dealu Mare-Tohani vineyard, production years 2003 and 2004, a greater difference in the ?(18)O values of wine water ranging from 1.89 (in 2004) to 5.35 ‰ (in 2003) was noted. This difference is explained by the different mean annual temperatures in 2003 and 2004. PMID:22397311

  20. Carbon and nitrogen stable isotope ratios in body tissue and mucus of feeding and fasting earthworms ( Lumbricus festivus )

    Microsoft Academic Search

    Olaf Schmidt; Charles M. Scrimgeour; James P. Curry

    1999-01-01

    We used natural abundance stable isotope techniques to estimate carbon and nitrogen turnover rates in body tissue and mucus\\u000a of earthworms. Isotope ratios of carbon (?13C) and nitrogen (?15N) were monitored simultaneously in body tissue and mucus for up to 101?days in feeding or fasting Lumbricus festivus kept in an artificial substrate. When the diet of the earthworms was switched

  1. Quinone-based stable isotope probing for assessment of 13C substrate-utilizing bacteria

    NASA Astrophysics Data System (ADS)

    Kunihiro, Tadao; Katayama, Arata; Demachi, Toyoko; Veuger, Bart; Boschker, Henricus T. S.; van Oevelen, Dick

    2015-04-01

    In this study, we attempted to establish quinone-stable-isotope probing (SIP) technique to link substrate-utilizing bacterial group to chemotaxonomic group in bacterial community. To identify metabolically active bacterial group in various environments, SIP techniques combined with biomarkers have been widely utilized as an attractive method for environmental study. Quantitative approaches of the SIP technique have unique advantage to assess substrate-incorporation into bacteria. As a most major quantitative approach, SIP technique based on phospholipid-derived fatty acids (PLFA) have been applied to simultaneously assess substrate-incorporation rate into bacteria and microbial community structure. This approach is powerful to estimate the incorporation rate because of the high sensitivity due to the detection by a gas chromatograph-combustion interface-isotope ratio mass spectrometer (GC-c-IRMS). However, its phylogenetic resolution is limited by specificity of a compound-specific marker. We focused on respiratory quinone as a biomarker. Our previous study found a good correlation between concentrations of bacteria-specific PLFAs and quinones over several orders of magnitude in various marine sediments, and the quinone method has a higher resolution (bacterial phylum level) for resolving differences in bacterial community composition more than that of bacterial PLFA. Therefore, respiratory quinones are potentially good biomarkers for quantitative approaches of the SIP technique. The LC-APCI-MS method as molecular-mass based detection method for quinone was developed and provides useful structural information for identifying quinone molecular species in environmental samples. LC-MS/MS on hybrid triple quadrupole/linear ion trap, which enables to simultaneously identify and quantify compounds in a single analysis, can detect high molecular compounds with their isotope ions. Use of LC-MS/MS allows us to develop quinone-SIP based on molecular mass differences due to 13C abundance in the quinone. In this study, we verified carbon stable isotope of quinone compared with bulk carbon stable isotope of bacterial culture. Results indicated a good correlation between carbon stable isotope of quinone compared with bulk carbon stable isotope. However, our measurement conditions for detection of quinone isotope-ions incurred underestimation of 13C abundance in the quinone. The quinone-SIP technique needs further optimization for measurement conditions of LC-MS/MS.

  2. In-Gel Stable-Isotope Labeling (ISIL): a strategy for mass spectrometry-based relative quantification.

    PubMed

    Asara, John M; Zhang, Xiang; Zheng, Bin; Christofk, Heather H; Wu, Ning; Cantley, Lewis C

    2006-01-01

    Most proteomics approaches for relative quantification of protein expression use a combination of stable-isotope labeling and mass spectrometry. Traditionally, researchers have used difference gel electrophoresis (DIGE) from stained 1D and 2D gels for relative quantification. While differences in protein staining intensity can often be visualized, abundant proteins can obscure less abundant proteins, and quantification of post-translational modifications is difficult. A method is presented for quantifying changes in the abundance of a specific protein or changes in specific modifications of a protein using In-gel Stable-Isotope Labeling (ISIL). Proteins extracted from any source (tissue, cell line, immunoprecipitate, etc.), treated under two experimental conditions, are resolved in separate lanes by gel electrophoresis. The regions of interest (visualized by staining) are reacted separately with light versus heavy isotope-labeled reagents, and the gel slices are then mixed and digested with proteases. The resulting peptides are then analyzed by LC-MS to determine relative abundance of light/heavy isotope pairs and analyzed by LC-MS/MS for identification of sequence and modifications. The strategy compares well with other relative quantification strategies, and in silico calculations reveal its effectiveness as a global relative quantification strategy. An advantage of ISIL is that visualization of gel differences can be used as a first quantification step followed by accurate and sensitive protein level stable-isotope labeling and mass spectrometry-based relative quantification. PMID:16396506

  3. Stable Isotope Evidence of Diet at Neolithic Çatalhöyük, Turkey

    Microsoft Academic Search

    M. P. Richards; J. A. Pearson; T. I. Molleson; N. Russell; L. Martin

    2003-01-01

    We report here new evidence for human subsistence from stable isotope analysis of humans and fauna from Catalhöyük. The analyses complement other lines of subsistence evidence, and indicate that, contrary to the original excavator James Mellaart's assertion (Mellaart, 1975), cattle was unlikely to have been the main source of dietary protein for all occupants. The analyses have also indicated the

  4. Neutron Stimulated Emission Computed Tomography of Stable Isotopes

    E-print Network

    Neutron Stimulated Emission Computed Tomography of Stable Isotopes Carey E. Floyd Jr.*ab , Calvin North Carolina Keywords: imaging, neutrons, tomography, spectroscopy ABSTRACT Here we report on the development of a new molecular imaging technique using inelastic scattering of fast neutrons. Earlier studies

  5. Stable Isotopic Constraints of the Turpan Basin in Northwestern China

    Microsoft Academic Search

    A. J. Schaen

    2010-01-01

    Stable isotopic analysis of sedimentary rocks can be used to reconstruct past geologic changes in the elevation and climate of topographic features such as mountain ranges and plateaus. The Tibetan Plateau is an ideal field laboratory for conducting this type of study because of the Plateau's extreme topographic relief and relatively recent geologic growth. Here we present oxygen and carbon

  6. Investigating surface waterwell interaction using stable isotope ratios of water*

    E-print Network

    wellshaveappreciablesurfacewatercontributionsandarepotentially vulnerable to contaminants in the surface water. When looking at wells with more than 6 sampling underlying the city and the river. Numerical ground- water-flow modeling (Hunt et al., 2003; Chapel et alInvestigating surface water­well interaction using stable isotope ratios of water* Randall J. Hunta

  7. From birds to butterflies: animal movement patterns and stable isotopes

    Microsoft Academic Search

    Dustin R. Rubenstein; Keith A. Hobson

    2004-01-01

    Establishing patterns of movement of wild animals is crucial for our understanding of their ecology, life history and behavior, and is a prerequisite for their effective conservation. Advances in the use of stable isotope markers make it possible to track a diversity of animal species in a variety of habitats. This approach is revolutionizing the way in which we make

  8. STABLE ISOTOPE TRACER MARKING OF INDIVIDUAL BOLL WEEVILS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable isotope markers have been used to study animal nutrition for several decades and more recently to study the foraging and cultural habits of imported fire ants. In this work, we have extended that effort to evaluate the potential for marking boll weevils with the rare earth element samarium. ...

  9. Development of stable isotope mixing models in ecology - Fremantle

    EPA Science Inventory

    More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...

  10. Development of stable isotope mixing models in ecology - Sydney

    EPA Science Inventory

    More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...

  11. STABLE ISOTOPE PROBING TO INVESTIGATE MICROBIAL FUNCTION IN SOIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most approaches for in situ phylogenetic characterization of soil microorganisms lack the ability to establish a causal relationship to function within the community. Recently, the use of stable isotopes to label phylogenetically informative biomolecules (phospholipid fatty acids, DNA, or RNA), typ...

  12. Development of stable isotope mixing models in ecology - Dublin

    EPA Science Inventory

    More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...

  13. Development of stable isotope mixing models in ecology - Perth

    EPA Science Inventory

    More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...

  14. Light stable isotope analysis of meteorites by ion microprobe

    NASA Technical Reports Server (NTRS)

    Mcsween, Harry Y., Jr.

    1994-01-01

    The main goal was to develop the necessary secondary ion mass spectrometer (SIMS) techniques to use a Cameca ims-4f ion microprobe to measure light stable isotope ratios (H, C, O and S) in situ and in non-conducting mineral phases. The intended application of these techniques was the analysis of meteorite samples, although the techniques that have been developed are equally applicable to the investigation of terrestrial samples. The first year established techniques for the analysis of O isotope ratios (delta O-18 and delta O-17) in conducting mineral phases and the measurement of S isotope ratios (delta S-34) in a variety of sulphide phases. In addition, a technique was developed to measure delta S-34 values in sulphates, which are insulators. Other research undertaken in the first year resulted in SIMS techniques for the measurement of wide variety of trace elements in carbonate minerals, with the aim of understanding the nature of alteration fluids in carbonaceous chondrites. In the second year we developed techniques for analyzing O isotope ratios in nonconducting mineral phases. These methods are potentially applicable to the measurement of other light stable isotopes such as H, C and S in insulators. Also, we have further explored the analytical techniques used for the analysis of S isotopes in sulphides by analyzing troilite in a number of L and H ordinary chondrites. This was done to see if there was any systematic differences with petrological type.

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

    PubMed

    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

  16. Biomedical research applications of electromagnetically separated enriched stable isotopes

    NASA Astrophysics Data System (ADS)

    Lambrecht, R. M.

    The current and projected annual requirements through 1985 for stable isotopes enriched by electromagnetic separation methods were reviewed for applications in various types of biomedical research: (1) medical radiosiotope production, labeled compounds, and potential radio-pharmaceuticals; (2) nutrition, food science, and pharmacology: (3) metallobiochemistry and environmental toxicology; (4) nuclear magnetic resonance, electron paramagnetic resonance, and moessbauer spectroscopy in biochemical, biophysical, and biomedical research; and (5) miscellaneous advances in radioactive and nonradioactive tracer technology. Radioisotopes available from commercial sources or routinely used in clinical nuclear medicine were excluded. Current requirements for enriched stable isotopes in biomedical research are not being satisfied. Severe shortages exist for Mg 26, Ca 43, Zn 70, Se 76, Se 77, Se 78, Pd 102, Cd 111, Cd 113, and Os 190. Many interesting and potentially important investigations in biomedical research require small quantities of specific elements at high isotopic enrichments.

  17. Equilibrium stable-isotope fractionation of thallium and mercury

    NASA Astrophysics Data System (ADS)

    Schauble, E. A.

    2005-12-01

    In this study first-principles quantum mechanical and empirical force-field models are used to estimate equilibrium mass-dependent isotopic fractionations among a variety of thallium and mercury compounds. High-precision MC-ICP-MS measurements have recently uncovered evidence of stable isotope fractionation for many elements, including 2-4‰ variability in the isotopic compositions of thallium[1] (atomic no. 81) and mercury[2] (atomic no. 80). The observed thallium- and mercury-isotope fractionations are remarkable, given that the magnitude of isotopic fractionation typically decreases as atomic number increases[3]. Stable isotope measurements could improve our understanding of geochemical and biogeochemical cycling of both elements, but little is known about the mechanisms driving these fractionations. A better understanding of the chemical processes controlling stable isotope compositions could help maximize the utility of these new geochemical tracers. Standard equilibrium stable isotope fractionation theory holds that the energy driving fractionation comes from isotopic effects on vibrational frequencies, which have generally not been measured. In the present study both quantum-mechanical and empirical force fields are used to estimate unknown frequencies. Results suggest that thallium and mercury fractionations of ? 0.5‰ are likely during the relevant redox reactions Tl+ ? Tl3+ and HgO ? Hg2+. Methyl-mercury and mercury-halide compounds like CH3HgCl will have ~ 1‰ higher 202Hg/198Hg than atomic vapor at room temperature. Fractionations between coexisting Hg2+ species appear to be much smaller, however. 205Tl/203Tl in Tl(H2O)_63+ is predicted to be ~0.5‰ higher than in coexisting Tl+-bearing substances. This result is in qualitative agreement with data from ferromanganese crusts [1], suggesting that Tl3+ in manganese-oxides will have higher 205Tl/203Tl than aqueous Tl+. Equilibrium fractionations for both elements are much smaller than the observed range of isotopic fractionations, however, which could point to a major role for kinetic-fractionation or Rayleigh-like distillation processes. Refs.: [1] Rehämper et al. (2002) EPSL 197:65. [2] Xie et al. (2005) J. Anal. Atomic Spectrom. 20:515. [3] Bigeleisen and Mayer (1947) J. Chem. Phys. 15:261.

  18. Stable isotope values of Costa Rican surface waters

    NASA Astrophysics Data System (ADS)

    Lachniet, Matthew S.; Patterson, William P.

    2002-03-01

    Stable isotope data of surface waters from the humid tropics in general, and Costa Rica in particular, are scarce. To improve our understanding of the spatial distribution of stable isotopes in surface waters, we measured ?18O and ?D in river and lake ( n=63) and precipitation ( n=3) samples from Costa Rica. We also present data from the IAEA/WMO isotopes in precipitation network as context for our study. Surface water isotope values do not strongly correlate with elevation, stream head elevation, stream length, distance from Caribbean Sea, or estimated mean annual precipitation for the country as a whole. However, the data show distinct regional trends. The ?18O and ?D values downwind of mountain ranges are inversely related to the altitude of the ranges the air masses traverse. In the lee of the high Talamanca Range, ?18O values are ˜6-8‰ lower, while in the lee of the lower Tilarán Range ?18O values are 2-3‰ lower than upwind sites along the Caribbean Slope. An altitude effect of -1.4‰ ?18O/km is present on the Pacific slope of southern Costa Rica, equivalent to a temperature effect of -0.3‰/°C. The Nicoya and Osa Peninsulas have higher values than upwind sites, suggesting input of Pacific-sourced moisture, evaporative enrichment, or decreased condensation temperatures. Elevated and increasing d-excess values inland along the Nicaragua Trough suggest a recycled component may be an important contributor to the water budget. These data provide preliminary stable isotope information for Costa Rica, and will benefit paleoclimatic research in the region. More detailed studies would be beneficial to our understanding of the controls on stable isotope composition of tropical waters.

  19. Stable isotopes in the diagnosis and treatment of inherited hyperammonemia

    PubMed Central

    Mew, Nicholas Ah; Yudkoff, Marc; Tuchman, Mendel

    2014-01-01

    Stable isotopes have greatly contributed to our understanding of nitrogen metabolism and the urea cycle. The measurement of urea flux via isotopic methods has traditionally been utilized to determine total body protein synthesis in subjects with an intact urea cycle. However, isotopic studies of nitrogen metabolism are also a useful adjunct to conventional clinical investigations in the diagnosis and management of the inherited hyperammonemias. Such studies offer a safe non-invasive method of measuring the reduction of in vivo hepatic ureagenesis, and thus may provide a more accurate measure of phenotypic severity in affected patients. In addition, isotopic methods are ideally suited to evaluate the efficacy of novel therapies to augment urea production. PMID:24634704

  20. Paleoenvironmental reconstruction of the Early to Middle Miocene Central Paratethys using stable isotopes from bryozoan skeletons

    NASA Astrophysics Data System (ADS)

    Key, Marcus M.; Zágoršek, Kamil; Patterson, William P.

    2013-01-01

    Stable carbon and oxygen isotope values from single bryozoan colonies were used to reconstruct the paleoenvironments of the Early to Middle Miocene (Ottnangian to Badenian) sediments of the Central Paratethys. This approach utilizes a locally abundant allochem while avoiding matrix and multiple allochem contamination from bulk rock samples. Bryozoan colonies (and a few foraminifera and rock matrix samples) from 14 localities yielded 399 carbon and oxygen isotope values. Data from six of the localities (15 % of the total number of samples) were interpreted as having been diagenetically altered and were rejected. The remaining data indicate a primarily localized upwelling signal with lesser variation caused by global climatic and regional tectonic forcing of sea level, salinity, and temperature. Paleotemperatures were calculated to range from 12 to 21 °C. Despite potential taxonomic and diagenetic problems, bryozoan colonies are a powerful, underutilized source of paleoenvironmental carbon and oxygen isotope data.

  1. Stable Isotope Analyses of water and Aqueous Solutions by Conventional Dual-inlet Mass Spectrometry

    SciTech Connect

    Horita, Juske [ORNL; Kendall, C. [U.S. Geological Survey, Menlo Park, CA

    2004-01-01

    The foundation of various analytical methods for the stable isotope composition of water and other aqueous samples (natural abundance, {sup 1}H : {sup 2}H (D) = 99.985 : 0.015 atom%, and {sup 16}O : {sup 17}O : {sup 18}O = 99.762 : 0.038 : 0.200 atom%) was established during the Manhatten Project in the U.S.A., when large amounts of heavy water were produced for nuclear reactors (see Kirshenbaum, 1951, for a detailed account). From early on, there was great interest in the oxygen and hydrogen isotopic compositions of water, because they are the ideal tracers of water sources and reactions. The increased analytical precisions made possible by the subsequent development of modern gas-source isotope-ratio mass spectrometers with dual-inlets and multi-collectors, have caused the proliferation of new analytical methods and applications for the oxygen and hydrogen isotopic compositions of water. These stable isotopes have found wide applications in basic as well as applied sciences (chemistry, geology, hydrology, biology, medical sciences, and food sciences). This is because water is ubiquitous, is an essential and predominant ingredient of living organisms, and is perhaps the most reactive compound in the Earth.

  2. Stable isotope patterns in micronekton from the Mozambique Channel

    NASA Astrophysics Data System (ADS)

    Ménard, Frédéric; Benivary, Hermann Doris; Bodin, Nathalie; Coffineau, Nathalie; Le Loc'h, François; Mison, Thomas; Richard, Pierre; Potier, Michel

    2014-02-01

    We measured the stable carbon (?13C) and nitrogen (?15N) isotopic composition of tissues of micronektonic organisms (fishes, squids, crustaceans and gelatinous organisms) collected in the Mozambique Channel during two scientific cruises in 2008 and 2009. The oceanic circulation in the Mozambique Channel is dominated by mesoscale cyclonic and anticyclonic eddies which play a key role in biological processes of less-productive deep-sea ecosystems. We investigated the potential impact of mesoscale features on the ?13C and ?15N values of 32 taxa of micronekton. Fishes, squids, crustaceans and gelatinous organisms encompassed a wide range of isotopic niches, with large overlaps among species. Our results showed that mesoscale features did not really influence the isotopic signatures of the sampled organisms, although cyclonic eddies can occasionally impact the nitrogen signatures of micronekton. We show that ?13C values were intermediate between standard offshore and nearshore signatures, suggesting that pelagic production in the Mozambique Channel could be partly supported by the transport and export of inorganic and organic particles from the Mozambican coast toward the offshore area. Trophic levels calculated from ?15N values ranged from 2.6 to 4.2, showing that micronekton taxa can be tertiary consumers in the Mozambique Channel. Our findings evidenced clusters of micronektonic organisms according to their ?15N or ?13C isotopic signatures, but variations in stable isotope values reflect a complex set of embedded processes linked to physical mesoscale dynamics (rotational dynamics of eddies) and basic biology and ecology of micronektonic organisms (vertical habitat, migration pattern, dietary habits, body length) that are discussed with regard to the stable isotope method based on time-integrated assimilated food.

  3. The Abundance and Isotopic Composition of Hg in Extraterrestrial Materials

    NASA Technical Reports Server (NTRS)

    Blum, J. D.; Klaue, Bjorn

    2005-01-01

    During the three year grant period we made excellent progress in our study of the abundances and isotopic compositions of Hg and other volatile trace elements in extraterrestrial materials. At the time the grant started, our collaborating PI, Dante Lauretts, was a postdoctoral research associate working with Peter Buseck at Arizona State University. The work on chondritic Hg was done in collaboration with Dante Lauretta and Peter Buseck and this study was published in Lauretta et a1 (2001a). In July, 2001 Dante Lauretta accepted a position as an Assistant Professor in the Lunar and Planetary Laboratory at the University of Arizona. His funding was transferred and this grant has supported much of his research activities during his first two years at the U of A. Several other papers are in preparation and will be published soon. We presented papers on this topic at Goldschmidt Conferences, the Lunar and Planetary Science Conferences, and the Annual Meetings of the Meteoritical Society. The work done under this grant has spurred several new directions of inquiry, which we are still pursuing. Included in this paper are the studies of bulk abundances and isotopic compositions of metreoritic Mercury, and the development of a thermal analysis ICP-MS technique applied to thermally liable elements.

  4. Intrinsic and Synthetic Stable Isotope Marking of Tsetse Flies

    PubMed Central

    Hood-Nowotny, Rebecca; Watzka, Margarete; Mayr, Leo; Mekonnen, Solomon; Kapitano, Berisha; Parker, Andrew

    2011-01-01

    The sterile insect technique has been successfully used to eliminate tsetse populations in a number of programs. Program monitoring in the field relies on the ability to accurately differentiate released sterile insects from wild insects so that estimates can be made of the ratio of sterile males to wild males. Typically, released flies are marked with a dye, which is not always reliable. The difference in isotopic signatures between wild and factory-reared populations could be a reliable and intrinsic secondary marker to complement existing marking methods. Isotopic signatures are natural differences in stable isotope composition of organisms due to discrimination against the heavier isotopes during some biological processes. As the isotopic signature of an organism is mainly dependent on what it eats; by feeding factory-reared flies isotopically different diets to those of the wild population it is possible to intrinsically mark the flies. To test this approach unlabeled samples of Glossina pallidipes (Austen) (Diptera: Glossinidae) from a mass rearing facility and wild populations were analyzed to determine whether there were any natural differences in signatures that could be used as markers. In addition experiments were conducted in which the blood diet was supplemented with isotopically enriched compounds and the persistence of the marker in the offspring determined. There were distinct natural isotopic differences between factory reared and wild tsetse populations that could be reliably used as population markers. It was also possible to rear artificially isotopically labeled flies using simple technology and these flies were clearly distinguishable from wild populations with greater than 95% certainty after 85 days of “release”. These techniques could be readily adopted for use in SIT programs as complimentary marking techniques. PMID:21870965

  5. Stable Isotope Mapping of Alaskan Grasses and Marijuana

    NASA Astrophysics Data System (ADS)

    Booth, A. L.; Wooller, M. J.

    2008-12-01

    The spatial variation of isotope signatures in organic material is a useful forensic tool, particularly when applied to the task of tracking the production and distribution of plant-derived illicit drugs. In order to identify the likely grow-locations of drugs such as marijuana from unknown locations (i.e., confiscated during trafficking), base isotope maps are needed that include measurements of plants from known grow-locations. This task is logistically challenging in remote, large regions such as Alaska. We are therefore investigating the potential of supplementing our base (marijuana) isotope maps with data derived from other plants from known locations and with greater spatial coverage in Alaska. These currently include >150 samples of modern C3 grasses (Poaceae) as well as marijuana samples (n = 18) from known grow-locations across the state. We conducted oxygen, carbon and nitrogen stable isotope analyses of marijuana and grasses (Poaceae). Poaceae samples were obtained from the University of Alaska Fairbanks (UAF) Museum of the North herbarium collection, originally collected by field botanists from around Alaska. Results indicate that the oxygen isotopic composition of these grasses range from 10‰ to 30‰, and broadly mirror the spatial pattern of water isotopes in Alaska. Our marijuana samples were confiscated around the state of Alaska and supplied to us by the UAF Police Department. ?13C, ?15N and ?18O values exhibit geographic patterns similar to the modern grasses, but carbon and nitrogen isotopes of some marijuana plants appear to be influenced by additional factors related to indoor growing conditions (supplementary CO2 sources and the application of organic fertilizer). As well as providing a potential forensic resource, our Poaceae isotope maps could serve additional value by providing resources for studying ecosystem nutrient cycling, for tracing natural ecological processes (i.e., animal migration and food web dynamics) and providing modern data for comparison with isotope analyses conducted on fossil leaf material in paleoecological studies.

  6. Fatty acid and stable carbon isotope characterization of Camelina sativa oil: implications for authentication.

    PubMed

    Hrastar, Robert; Petrisic, Marinka G; Ogrinc, Nives; Kosir, Iztok Joze

    2009-01-28

    The importance of authenticity characterization is an increasing and pressing requirement for all foods. Vegetable oil is one of the most studied foods because of its nutritional and medicinal properties in a correct diet. In this study, a total of 53 Camelina sativa samples, from all known growing areas, were chemically and isotopically characterized. The fatty acid content of camelina oil was determined by gas chromatography (GC), and the ratios of stable carbon isotopes ((13)C/(12)C) of individual fatty acids and seed/bulk oil were determined by gas chromatography-combustion-stable isotope ratio mass spectrometry (GC/C/IRMS) and elemental analysis-stable isotope ratio mass spectrometry (IRMS). A total of 17 different fatty acids were detected by GC, with omega3 R-linolenic acid (C(18:3n3)) being the most abundant (29.7-40.0 wt %). Oleic acid (C(18:1n9)), linoleic acid (C(18:2n6)) and eicosenoic acid (C(20:1n9)) all belong to the second group of major fatty acids. The stable carbon isotopic values (delta(13)C) fell into a range typical for C(3) plants. The use of delta(13)C(18:2n6) vs delta(13)C(18:3n3) correlation could show cases where impurity or adulteration is suspected, whereas principal component analysis clearly separates oil samples from different continents. Preliminary results on the camelina oil authentication procedure provide a basis for the investigation of geographical origin and the further distinction between camelina and camelina refined or other, less expensive oils. PMID:19123821

  7. Nitrogen stable isotopes in primary uptake compartments across streams differing in nutrient availability.

    PubMed

    Pastor, Ada; Peipoch, Marc; Cañas, Lídia; Chappuis, Eglantine; Ribot, Miquel; Gacia, Esperança; Riera, Joan Lluís; Martí, Eugènia; Sabater, Francesc

    2013-09-17

    High variability in the natural abundance of nitrogen stable isotopes (?(15)N) has been reported for primary uptake compartments (PUCs; e.g., epilithon, filamentous algae, bryophytes, macrophytes) in human-impacted aquatic ecosystems, but the origin of this variability is not yet well understood. We examined how ?(15)N of different PUC types relate to ?(15)N of dissolved inorganic nitrogen (DIN) species (nitrate and ammonium) and to the stream nutrient concentrations in which they grow. We selected 25 reaches located across the fluvial network of La Tordera catchment (NE Spain, 868.5 km(2)), encompassing a gradient of human pressures from headwaters to the river valley. ?(15)N-PUC variability was mostly explained by location within the fluvial network and was strongly related to the ?(15)N of DIN species, especially of ammonium. Models were stronger for PUCs growing within the stream channel and thus using streamwater as their main source of nutrients. Regression models including nutrient concentrations improved the prediction power for ?(15)N-PUCs, suggesting that nutrient concentrations and stoichiometry cannot be ignored in explaining the natural abundance of nitrogen isotopes in PUCs. These results provide insights into what controls variability in ?(15)N of PUCs within a stream network, with implications for the application of stables isotopes as an ecological tool. PMID:23930789

  8. Stable isotope dilution analyses of molybdenum in meteorites.

    PubMed

    Wieser, M E; De Laeter, J R

    2000-01-01

    Isotope dilution mass spectrometry is an ideal analytical technique to measure the elemental abundance of Mo in C1 carbonaceous chondrites and the metallic and troilite phases of iron meteorites. The mean abundance of Mo in two C1 meteorites is 0.909+/-0.040 microg/g which corresponds to a value of 2.55 atoms Mo with respect to Si equal to 10(6) atoms, which is identical to the currently accepted solar system abundance. The partitioning of Mo between the metallic and sulfide phases in the Mundrabilla iron meteorite was found to be 6.0+/-0.2 microg/g and 8.6+/-0.3 microg/g, respectively. A new, precise Mo concentration of 1.54+/-0.04 microg/g for the Geochemical Reference Standard BCR-1 is also reported. PMID:11220597

  9. Comparative Glycomics using A Tetraplex Stable-Isotope Coded Tag

    PubMed Central

    Bowman, Michael J.; Zaia, Joseph

    2010-01-01

    This study illustrates the utility of tetraplex stable isotope coded tags in mass spectrometric glycomics using three carbohydrate classes. The teteraplex tags allow for the direct comparison of glycan compositions within four samples using capillary scale hydrophilic interaction chromatography with on-line mass spectrometry. In addition, the ability to discern glycan structural isomers is shown based on the tandem mass spectra of each composition using nanospray ionization. Results are shown for chondroitin sulfate proteoglycans, low molecular weight heparins, full length heparins, and N-glycans from ?-1-acid glycoproteins from four mammalian species. The data demonstrate the value of the tetraplex stable isotope tagging approach for producing high quality glycomics compositional profiling and fine structural analysis. PMID:20230064

  10. Water vapor stable isotope observations from tropical Australia

    NASA Astrophysics Data System (ADS)

    Parkes, Stephen; Deutscher, Nicholas; Griffith, David; McCabe, Matthew

    2015-04-01

    The response of the tropical hydrological cycle to anthropogenically induced changes in radiative forcing is one of the largest discrepancies between climate models. Paleoclimate archives of the stable isotopic composition of precipitation in the tropics indicate a relationship with precipitation amount that could be exploited to study past hydroclimate and improve our knowledge of how this region responds to changes in climate forcing. Recently modelling studies of convective parameterizations fitted with water isotopes and remote sensing of water vapor isotopes in the tropics have illustrated uncertainty in the assumed relationship with rainfall amount. Therefore there is a need to collect water isotope data in the tropics that can be used to evaluate these models and help identify the relationships between the isotopic composition of meteoric waters and rainfall intensity. However, data in this region is almost non-existent. Here we present in-situ water vapor isotopic measurements and the HDO retrievals from the co-located Total Column Carbon Observing Network (TCCON) site at Darwin in Tropical Australia. The Darwin site is interestingly placed within the tropical western pacific region and is impacted upon by a clear monsoonal climate, and key climate cycles including ENSO and Madden Julian Oscillations. The analysis of the data illustrated relationships between water vapor isotopes and humidity which demonstrated the role of precipitation processes in the wet season and air mass mixing during the dry season. Further the wet season observations show complex relationships between humidity and isotopes. A simple Rayleigh distillation model was not obeyed, instead the importance of rainfall re-evaporation in generating the highly depleted signatures was demonstrated. These data potentially provide a useful tool for evaluating model parameterizations in monsoonal regions as they demonstrate relationships with precipitation processes that cannot be observed with more traditional observations.

  11. Stable isotopic composition of bottled mineral waters from Romania

    NASA Astrophysics Data System (ADS)

    B?d?lu??, Carmen; Nagavciuc, Viorica; Per?oiu, Aurel

    2015-04-01

    Romania has a high potential of mineral waters resources, featuring one of the largest mineral resources at European and global level. In the last decade, due to increased in consumption of bottled water, numerous brands have appeared on the market, with equally numerous and variable sources of provenance. In this study we have analyzed the isotopic composition of bottled mineral waters from Romania in order to determine their source and authenticity. We have analysed 32 carbonated and 24 non-carbonated mineral waters from Romania. and the results were analysed in comparison with stable isotope data from precipitation and river waters. Generally, the isotopic values of the mineral waters follow those in precipitation; however, differences occur in former volcanic regions (due to deep circulation of meteoric waters and increased exchange with host rock and volcanic CO2), as well as in mountainous regions, where high-altitude recharge occurs.

  12. A preliminary stable isotope study on Mogok Ruby, Myanmar

    Microsoft Academic Search

    Tzen-Fu Yui; Khin Zaw; Chao-Ming Wu

    2008-01-01

    The primary occurrence of ruby in the Mogok area, northern Myanmar is exclusively found in marble along with spinel–forsterite-bearing marble and phlogopite–graphite marble. These marble units are enclosed within banded biotite–garnet–sillimanite–oligoclase gneisses. Samples of these marbles collected for C–O stable isotope analysis show two trends of ?13C–?18O variation resulting most likely from fluid–rock interactions. Ruby-bearing marble and phlogopite–graphite marble follow

  13. Feeding guilds in Collembola based on nitrogen stable isotope ratios

    Microsoft Academic Search

    Masoumeh Chahartaghi; Reinhard Langel; Stefan Scheu; Liliane Ruess

    2005-01-01

    In soil a high number of species co-exist without extensive niche differentiation, which was assigned as ‘the enigma of soil animal species diversity’. In particular, the detritivores are regarded as food generalists. We have investigated nitrogen stable isotope ratios (15N\\/14N) of a major decomposer group, the Collembola, to evaluate trophic relationship and determine feeding guilds. Additionally, the ?15N values of

  14. Stable Carbon Isotopes As Indicators of Plant Water Use Efficiency

    Microsoft Academic Search

    E. M. Powers; J. D. Marshall; N. Ubierna Lopez

    2007-01-01

    Stable carbon isotopes have been utilized to better understand how environmental variables influence the efficiency of photosynthesis, specifically what factors limit the uptake and absorption of CO2 during photosynthesis. An understanding of the controls over both gas exchange and stomatal conductance can provide an explanation for the possible environmental influences on plant WUE. The delta13C of extractive-free wood was used

  15. The use of stable carbon isotope analysis in rooting studies

    Microsoft Academic Search

    Tony J. Svejcar; Thomas W. Boutton

    1985-01-01

    Stable carbon isotope analysis was evaluated as a means of predicting the relative proportions of C3 and C4 root phytomass in species mixtures. The following mixtures of C3 and C4 species were used: 1) big bluestem (Andropogon gerardii)\\/cheatgrass (Bromus tectorum), 2) little bluestem (Schizachyrium scoparium)\\/cheatgrass, and 3) sorghum (Sorghum bicolor)\\/sunflower (Helianthus annuus). There was a significant correlation (P4 phytomass and

  16. Calibration of stable oxygen isotopes in Siderastrea radians (Cnidaria:Scleractinia): Implications for slow-growing corals

    E-print Network

    Swart, Peter K.

    Calibration of stable oxygen isotopes in Siderastrea radians (Cnidaria:Scleractinia): Implications. Swart, and R. E. Dodge (2006), Calibration of stable oxygen isotopes in Siderastrea radians (Cnidaria

  17. Paleoclimate and Amerindians: evidence from stable isotopes and atmospheric circulation.

    PubMed

    Lovvorn, M B; Frison, G C; Tieszen, L L

    2001-02-27

    Two Amerindian demographic shifts are attributed to climate change in the northwest plains of North America: at approximately 11,000 calendar years before present (yr BP), Amerindian culture apparently split into foothills-mountains vs. plains biomes; and from 8,000-5,000 yr BP, scarce archaeological sites on the open plains suggest emigration during xeric "Altithermal" conditions. We reconstructed paleoclimates from stable isotopes in prehistoric bison bone and relations between weather and fractions of C(4) plants in forage. Further, we developed a climate-change model that synthesized stable isotope, existing qualitative evidence (e.g., palynological, erosional), and global climate mechanisms affecting this midlatitude region. Our isotope data indicate significant warming from approximately 12,400 to 11,900 yr BP, supporting climate-driven cultural separation. However, isotope evidence of apparently wet, warm conditions at 7,300 yr BP refutes emigration to avoid xeric conditions. Scarcity of archaeological sites is best explained by rapid climate fluctuations after catastrophic draining of the Laurentide Lakes, which disrupted North Atlantic Deep Water production and subsequently altered monsoonal inputs to the open plains. PMID:11226265

  18. Paleoclimate and Amerindians: Evidence from stable isotopes and atmospheric circulation

    PubMed Central

    Lovvorn, Marjorie Brooks; Frison, George C.; Tieszen, Larry L.

    2001-01-01

    Two Amerindian demographic shifts are attributed to climate change in the northwest plains of North America: at ?11,000 calendar years before present (yr BP), Amerindian culture apparently split into foothills–mountains vs. plains biomes; and from 8,000–5,000 yr BP, scarce archaeological sites on the open plains suggest emigration during xeric “Altithermal” conditions. We reconstructed paleoclimates from stable isotopes in prehistoric bison bone and relations between weather and fractions of C4 plants in forage. Further, we developed a climate-change model that synthesized stable isotope, existing qualitative evidence (e.g., palynological, erosional), and global climate mechanisms affecting this midlatitude region. Our isotope data indicate significant warming from ?12,400 to 11,900 yr BP, supporting climate-driven cultural separation. However, isotope evidence of apparently wet, warm conditions at 7,300 yr BP refutes emigration to avoid xeric conditions. Scarcity of archaeological sites is best explained by rapid climate fluctuations after catastrophic draining of the Laurentide Lakes, which disrupted North Atlantic Deep Water production and subsequently altered monsoonal inputs to the open plains. PMID:11226265

  19. Diets of introduced predators using stable isotopes and stomach contents

    USGS Publications Warehouse

    Meckstroth, A.M.; Miles, A.K.; Chandra, S.

    2007-01-01

    In a study of predation on ground-nesting birds at South San Francisco Bay (South Bay), California, USA, we analyzed stomach contents and stable isotopes of carbon and nitrogen to identify commonly consumed prey. We obtained the stomach contents from 206 nonnative red foxes (Vulpes vulpes regalis) collected in the South Bay area and Monterey County during 1995-2001 and from 68 feral cats (Felis silvestris) from the South Bay area during 2001-2002. We determined prey identity, biomass, and frequency, described seasonal diet trends, and derived an Index of Relative Importance. Avian species were the most frequent prey we found in the stomachs of red foxes from South Bay (61%), whereas small rodents were most frequent for red foxes from Monterey County (62%). Small rodents were the most frequent prey we found in feral cats (63%). Carbon and nitrogen isotopic signatures for foxes supported stomach content findings. However, isotope results indicated that cats received a majority of their energy from a source other than rodents and outside the natural system, which differed from the stomach content analysis. We demonstrated the utility of both stable isotope and stomach content analyses to establish a more complete understanding of predators' diets. This information aids natural resource managers in planning and evaluating future predator-removal programs and increases our understanding of the impacts of nonnative foxes and cats on native species.

  20. Guidelines and recommended terms for expression of stable-isotope-ratio and gas-ratio measurement results

    USGS Publications Warehouse

    Coplen, Tyler B.

    2011-01-01

    To minimize confusion in the expression of measurement results of stable isotope and gas-ratio measurements, recommendations based on publications of the Commission on Isotopic Abundances and Atomic Weights of the International Union of Pure and Applied Chemistry (IUPAC) are presented. Whenever feasible, entries are consistent with the Système International d'Unités, the SI (known in English as the International System of Units), and the third edition of the International Vocabulary of Basic and General Terms in Metrology (VIM, 3rd edition). The recommendations presented herein are approved by the Commission on Isotopic Abundances and Atomic Weights and are designed to clarify expression of quantities related to measurement of isotope and gas ratios to ensure that quantity equations instead of numerical value equations are used for quantity definitions. Examples of column headings consistent with quantity calculus (also called the algebra of quantities) and examples of various deprecated usages connected with the terms recommended are presented.

  1. Investigating microbial carbon cycling using natural abundance isotope analysis of PLFA

    NASA Astrophysics Data System (ADS)

    Slater, G. G.; Brady, A.; Cowie, B.

    2008-12-01

    Understanding microbial carbon sources and cycling is fundamental to our conceptualization of microbial ecosystems and their role in biogeochemical cycling in natural systems. Achieving this understanding requires application of a wide range of approaches. Natural abundance isotope analysis of individual compounds, particularly cellular components such as Phospholipids Fatty Acids (PLFA) can provide insights into the carbon sources and metabolic activities of the in situ microbial community from environmental samples. This is primarily because specific PLFA can be well resolved by gas chromatography even from complex matrices where confounding biological/organic compound abound. These PLFA can then be attributed to the viable microbial community, in some cases to specific components of this community and due to characteristic biosynthetic fractionations of stable isotope ratios, ?13C analysis of PLFA can: differentiate isotopically distinct primary carbon sources of heterotrophic communities; identify isotopic patterns characteristic of autotrophic versus heterotrophic processes; and elucidate microbial biosynthetic pathways. In cases where there ?13C cannot provide resolution of carbon sources, new approaches in ?14C of PLFA can be applied. The vast range in ?14C of ancient and modern carbon provides an easily traceable signal that can differentiate uptake and utilization of these carbon sources. This is particularly useful in cases such as contaminated sites where petroleum based contamination has occurred, or in natural systems where microbial communities may be utilizing geologic versus recently photosynthetically fixed carbon. This talk will present several examples demonstrating the utility of this approach.

  2. High Spatial Resolution Isotopic Abundance Measurements by Secondary Ion Mass Spectrometry: Status and Prospects

    NASA Astrophysics Data System (ADS)

    McKeegan, K. D.

    2007-12-01

    Secondary Ion Mass Spectrometry, SIMS or ion microprobe analysis, has become an important tool for geochemistry because of its ability study the distributions of elemental and isotopic abundances in situ on polished samples with high (typically a few microns to sub-micron) spatial resolution. In addition, SIMS exhibits high sensitivity for a wide range of elements (H to Pu) so that isotope analyses can sometimes be performed for elements that comprise only trace quantities of some mineral phase (e.g., Pb in zircon) or on major and/or minor elements in very small samples (e.g., presolar dust grains). Offsetting these positive attributes are analytical difficulties due to the complexity of the sputtering source of analyte ions: (1) relatively efficient production of molecular ion species (especially from a complex matrix such as most natural minerals) that cause interferences at the same nominal mass as atomic ions of interest, and (2) quantitation problems caused by variations in the ionization efficiencies of different elements and/or isotopes depending upon the chemical state of the sample surface during sputtering--the so-called "matrix effects". Despite the availability of high mass resolution instruments (e.g., SHRIMP II/RG, CAMECA 1270/1280/NanoSIMS), the molecular ion interferences effectively limit the region of the mass table that can be investigated in most samples to isotope systems at Ni or lighter or at Os or heavier. The matrix effects and the sensitivity of instrumental mass discrimination to the physical state of the sample surface can hamper reproducibility and have contributed to a view that SIMS analyses, especially for so- called stable isotopes, are most appropriate for extraterrestrial samples which are often small, rare, and can exhibit large magnitude isotopic effects. Recent improvements in instrumentation and technique have extended the scope of SIMS isotopic analyses and applications now range from geochronology to paleoclimatology to volcanology to biogeochemistry and cosmochemistry. Multiple collector (static magnetic field) measurements at high mass resolving power have enabled high precision (sub-permil) for several stable isotopes systems (e.g., C, O, Mg, S). Applied to geochronology, the multiple collector approach permits very rapid survey of zircon Pb-Pb ages to identify candidate Hadean grains for further detailed analysis. Ion imaging has been used to correlate isotope compositions with biochemistry (e.g., FISH-SIMS) or to search for especially rare samples among larger populations (e.g., supernova grains of Stardust). For favorable sample geometries with lateral homogeneity, SIMS isotope analyses may be conducted in depth-profiling mode which brings spatial resolution into the tens of nm range. Applications of this approach include experimental petrology, thermochronology, and isotopic analyses of shallowly-implanted solar wind ions. New approaches to removal of molecular ion interferences include reverse- geometry instrumentation and accelerator-based SIMS. There always exists trade-offs between microanalysis and trace analysis on the one hand, and high precision on the other. In this contribution, I will review current status for isotope precision and accuracy of SIMS for applications in stable and radiogenic isotopes as a function of spatial scale. A discussion of current limits and future prospects for improvement in understanding matrix effects will be given. Examples from ion imaging/ depth profiling/ geochronology and cosmochemistry will be provided.

  3. Estimation of evapotranspiration rate in irrigated lands using stable isotopes

    NASA Astrophysics Data System (ADS)

    Umirzakov, Gulomjon; Windhorst, David; Forkutsa, Irina; Brauer, Lutz; Frede, Hans-Georg

    2013-04-01

    Agriculture in the Aral Sea basin is the main consumer of water resources and due to the current agricultural management practices inefficient water usage causes huge losses of freshwater resources. There is huge potential to save water resources in order to reach a more efficient water use in irrigated areas. Therefore, research is required to reveal the mechanisms of hydrological fluxes in irrigated areas. This paper focuses on estimation of evapotranspiration which is one of the crucial components in the water balance of irrigated lands. Our main objective is to estimate the rate of evapotranspiration on irrigated lands and partitioning of evaporation into transpiration using stable isotopes measurements. Experiments has done in 2 different soil types (sandy and sandy loam) irrigated areas in Ferghana Valley (Uzbekistan). Soil samples were collected during the vegetation period. The soil water from these samples was extracted via a cryogenic extraction method and analyzed for the isotopic ratio of the water isotopes (2H and 18O) based on a laser spectroscopy method (DLT 100, Los Gatos USA). Evapotranspiration rates were estimated with Isotope Mass Balance method. The results of evapotranspiration obtained using isotope mass balance method is compared with the results of Catchment Modeling Framework -1D model results which has done in the same area and the same time.

  4. Bone as a stable isotope archive for local climatic information

    NASA Astrophysics Data System (ADS)

    Hedges, Robert E. M.; Stevens, Rhiannon E.; Richards, Michael. P.

    2004-04-01

    This brief review outlines the contribution that the study of stable isotope composition in bone can make to palaeoclimatic investigation, with the focus almost entirely restricted to the last 50,000 years in NW Europe. Bone can provide a useful archive of the prevailing isotopic condition, and represents a quite different, and often less specialised, sampling of the environment than most other archives. On the other hand, chronological sequences—and dating generally—can be a problem, and the link between the isotopic value registered in the bone, and the environmental conditions which gave rise to it, is both complex and not fully understood. Carbon, oxygen and nitrogen isotopes are all available from bone (nitrogen only where sufficient protein (collagen) survives), and are all subject, in different ways, to climatic influences such as temperature, rainfall, changes in floristic composition, and soil chemistry. These are all briefly discussed, and the datasets that are being published are considered in the context of the environmental information they provide. Undoubtedly environmental signals are recoverable, but their interpretation is still primitive. A dataset for carbon and nitrogen isotope composition of herbivores that spans the last 50,000 years is shown together with some of the issues it raises.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Geographic variation of stable isotopes in African elephant ivory

    NASA Astrophysics Data System (ADS)

    Ziegler, S.; Merker, S.; Jacob, D.

    2012-04-01

    In 1989, the international community listed the African elephant in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) thus prohibiting commercial ivory trade. Recent surveillance data show that the illegal trade in ivory has been growing worldwide. Long-term preservation of many of the African elephant populations can be supported with a control mechanism that helps with the implementation of remedial conservation action. Therefore, setting up a reference database that predicts the origin of ivory specimens can assist in determining smuggling routes and the provenance of illegal ivory. Our research builds on earlier work to seek an appropriate method for determining the area of origin for individual tusks. Several researchers have shown that the provenance of elephant ivory can be traced by its isotopic composition, but this is the first attempt to produce an integrated isotopic reference database of elephant ivory provenance. We applied a combination of various routine geochemical analyses to measure the stable isotope ratios of hydrogen, carbon, nitrogen, oxygen, and sulphur. Up to now, we analysed 606 ivory samples of known geographical origin from African range states, museums and private collections, comprising 22 African elephant range states. The isotopic measurements were superimposed with data layers from vegetation, geology and climate. A regression function for the isotope composition of the water isotopes in precipitation and collagen in ivory was developed to overcome the problem of imprecise origin of some of the sampled material. Multivariate statistics, such as nearest neighborhood and discriminate analysis were applied to eventually allow a statistical determination of the provenance for ivory of unknown origin. Our results suggest that the combination of isotopic parameters have the potential to provide predictable and complementary markers for estimating the origin of seized elephant ivory.

  7. Magnesium stable isotope ecology using mammal tooth enamel

    PubMed Central

    Martin, Jeremy E.; Vance, Derek; Balter, Vincent

    2015-01-01

    Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (?13C) and to a lesser extent on strontium/calcium (Sr/Ca) and barium/calcium (Ba/Ca) elemental ratios. Recent developments in nontraditional stable isotopes provide an unprecedented opportunity to use additional paleodietary proxies to disentangle complex diets such as omnivory. Of particular relevance for paleodietary reconstruction are metals present in large quantity in bone and enamel apatite, providing that biologically mediated fractionation processes are constrained. Calcium isotope ratios (?44Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (?26Mg) also meet these criteria but a comprehensive understanding of its variability awaits new isotopic data. Here, 11 extant mammal species of known ecology from a single locality in equatorial Africa were sampled for tooth enamel and, together with vegetation and feces, analyzed for ?26Mg, ?13C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that ?26Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this 26Mg enrichment up the trophic chain is due to a 26Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using ?26Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel ?26Mg composition remain to be explored but, in the future, multiproxy approaches would permit a substantial refinement of dietary behaviors or enable accurate trophic reconstruction despite specimen-limited sampling, as is often the case for fossil assemblages. PMID:25535375

  8. High-resolution analysis of Quaternary calcretes: a coupled stable isotope and micromorphological approach

    NASA Astrophysics Data System (ADS)

    Adamson, Kathryn; Candy, Ian; Whitfield, Liz

    2015-04-01

    Pedogenic calcretes are abundant in arid and semi-arid regions, and they are widely used as proxy records of palaeoclimatic change. Calcrete oxygen (?18O) and carbon (?13C) isotopic signatures are indicative of temperature, aridity, or vegetation at the time of calcrete formation. Their microfabrics also reflect carbonate formation mechanisms in response to the prevailing environmental conditions. Many studies have explored calcrete micromorphology or stable isotope composition, but these techniques have not yet been applied simultaneously. This co-analysis is important as it allows us to establish whether calcrete morphology directly reflects environmental change. This study tests the potential of combining these analyses to examine the relationships between calcrete microfabrics, their isotopic signals, and Quaternary climate change. Calcretes from four river terraces of the Rio Alias in southeast Spain have been analysed in detail. On the basis of morphostratigraphic correlation (Maher et al., 2007) and Uranium-series ages (Candy et al., 2005), these span the period from 304 ± 26 ka (MIS 9) to the Holocene. The oldest profiles have therefore been exposed to multiple glacial-interglacial cycles. A total of 37 micromorphological profiles have been used to extract stable oxygen and carbon isotopic indicators from 77 microfacies. The morphological and isotopic complexity of the calcrete profiles increases with progressive age. The oldest samples display multiple calcretisation phases, and their microfabrics have a larger isotopic range than the younger samples. Alpha (non-biogenic) fabrics have higher ?13C and ?18O values than beta (biogenic) fabrics. Strong positive covariance between ?13C and ?18O within all profiles suggests that both isotopes are responding to the same environmental parameter. We suggest that this is relative aridity. The study demonstrates that the detailed co-analysis of calcrete micromorphology and stable isotope signatures allows calcrete formation patterns to be placed into a wider palaeoclimatic context. Importantly, this technique provides a level of detail that is not possible through bulk isotope sampling alone. It demonstrates the potential of this technique to more reliably constrain the palaeoenvironmental significance of secondary carbonates in dryland settings where other proxy records may be poorly preserved.

  9. The abundances of elements and isotopes in the solar wind

    NASA Technical Reports Server (NTRS)

    Gloeckler, George; Geiss, Johannes

    1989-01-01

    Solar wind abundances have now been measured for eleven elements and the isotopes of the noble gases. Aside from solar wind protons and alpha particles, which have been studied extensively since the 1960's, information for heavier elements is limited. Nevertheless, two effects stand out. First is the enrichment of abundances of elements with low first ionization potential (FIP), most likely the combined result of an atom-ion separation process in the upper chromosphere, and a marginal coupling of low-charge-state heavy ions to protons and alphas during the acceleration of the solar wind. Second, there is variability in the solar wind composition over a whole range of time scales. Recent measurements carried out in the earth's magnetosheath during times that included high-speed coronal-hole-associated flows indicate a significantly lower overabundance of low FIP elements. Given the fact that the He/H ratio is remarkably constant in the coronal hole solar wind, this result suggests that both enrichment and variability are reduced in such flows.

  10. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies.

    PubMed

    Wong, William W; Clarke, Lucinda L

    2012-11-01

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to hydrogen gas (H(2)) for mass spectrometric analysis are labor intensive, require special reagent, and involve memory effect and potential isotope fractionation. The objective of this study was to determine the accuracy and precision of a platinum catalyzed H(2)-water equilibration method for stable hydrogen isotope ratio measurements. Time to reach isotopic equilibrium, day-to-day and week-to-week reproducibility, accuracy, and precision of stable hydrogen isotope ratio measurements by the H(2)-water equilibration method were assessed using a Thermo DELTA V Advantage continuous-flow isotope ratio mass spectrometer. It took 3 h to reach isotopic equilibrium. The day-to-day and week-to-week measurements on water and urine samples with natural abundance and enriched levels of deuterium were highly reproducible. The method was accurate to within 2.8 (o)/oo and reproducible to within 4.0 (o)/oo based on analysis of international references. All the outcome variables, whether in urine samples collected in 10 doubly labeled water studies or plasma samples collected in 26 body water studies, did not differ from those obtained using the reference zinc reduction method. The method produced highly accurate estimation on ad libitum energy intakes, body composition, and water turnover rates. The method greatly reduces the analytical cost and could easily be adopted by laboratories equipped with a continuous-flow isotope ratio mass spectrometer. PMID:23014490

  11. A NEW CALCULATION FOR THE AGE OF THE EARTH FROM ABUNDANCES OF LEAD ISOTOPES

    Microsoft Academic Search

    R. G. Ostic; R. D. Russell; P. H. Reynolds

    1963-01-01

    A new method, basically distinct from the two most common methods, is ; suggested for calculating the age of the Earth from lead isotope abundances. In ; common with other methods, the new method assumes that the samples used in the ; calculation can be interpreted by equations appropriate to evolution of the lead ; isotope abundances in a single

  12. Analytical techniques in biomedical stable isotope applications: (isotope ratio) mass spectrometry or infrared spectrometry?

    Microsoft Academic Search

    Frans Stellaard; Henk Elzinga

    2005-01-01

    An overview is presented of biomedical applications of stable isotopes in general, but mainly focused on the activities of the Center for Liver, Digestive and Metabolic Diseases of the University Medical Center Groningen. The aims of metabolic studies in the areas of glucose, fat, cholesterol and protein metabolism are briefly explained, as well as the principle of breath testing and

  13. Chromium Stable Isotope Fractionation - An Indicator of Hexavalent Chromium Reduction.

    NASA Astrophysics Data System (ADS)

    Ellis, A.; Johnson, T. M.; Bullen, T. D.

    2001-12-01

    Chromium is a common anthropogenic contaminant in surface water and ground water, and is also of interest in oceanography. It is redox-active; the two common valences in natural waters are Cr(VI), which is highly soluble and toxic, and Cr(III), which is relatively insoluble. Redox reactions thus control Cr mobility in aqueous solutions, and reduction of Cr(VI) to Cr(III) is the most important reaction controlling attenuation of Cr in groundwater. Our results show that Cr(VI) reduction favors the lighter isotopes and leads to enrichment of heavier isotopes in the remaining Cr(VI). Cr isotope measurements thus show great promise as indicators of Cr(VI) reduction. We report here the first measurements of the magnitude of Cr isotope fractionation during Cr(VI) reduction and variations in ? 53Cr values obtained from three contaminated sites. Experiments were conducted to measure Cr isotope fractionation during Cr(VI) reduction by suspensions of magnetite and unamended sediments from a local pond, Urbana, IL and San Francisco Estuary near Martinez, CA. Suspensions were incubated anaerobically with constant shaking, and complete Cr(VI) reduction occurred within a few days. Cr(VI) from intermediate time points in the experiments was purified via ion exchange and 53Cr/52Cr ratios were measured via TIMS with a double isotope spike. The instantaneous per mil fractionation, ? , was calculated assuming a Rayleigh fractionation model. The ? for Cr(VI) reduction on magnetite surfaces yielded a fractionation of -3.5 ‰ . The ? values for the pond and estuary sediments were -3.5 ‰ and -3.3 ‰ respectively. The size of this Cr isotope fractionation is encouraging, as current precision is 0.2 \\permil. ? 53Cr values in dissolved Cr(VI) from three contaminated sites range from 1.1 ‰ to 5.8 ‰ , suggesting that Cr(VI) reduction has occurred and has induced isotopic fractionation in these settings. ? 53Cr values measured from Cr(VI) in plating baths show little or no fractionation during plating operations during up to 5 years of use. These results demonstrate that Cr stable isotope analyses should be a highly practical indicator of the critical chromate reduction reaction, and an otherwise useful geologic and oceanographic tool.

  14. Stable isotope analysis using tunable diode laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Becker, Joseph F.; Sauke, Todd B.; Loewenstein, Max

    1992-01-01

    Ratios of C-12/C-13 in CO2 have been measured using a tunable diode laser (TDL) spectrometer to an accuracy of better than 0.4 percent. These results were made possible by the use of state-of-the-art high-temperature TDLs, an etalon and wavenumber calibration technique, high-speed assembly language controlled data acquisition, and the ratioing of absorbances from simultaneously acquired sample and reference data scans. The dual beam spectrometer that is employed uses the sweep integration technique in a spectral region where adjacent spectral lines are of approximately equal absorbance at the expected isotopic abundances.

  15. Calcium kinetics with microgram stable isotope doses and saliva sampling

    NASA Technical Reports Server (NTRS)

    Smith, S. M.; Wastney, M. E.; Nyquist, L. E.; Shih, C. Y.; Wiesmann, H.; Nillen, J. L.; Lane, H. W.

    1996-01-01

    Studies of calcium kinetics require administration of tracer doses of calcium and subsequent repeated sampling of biological fluids. This study was designed to develop techniques that would allow estimation of calcium kinetics by using small (micrograms) doses of isotopes instead of the more common large (mg) doses to minimize tracer perturbation of the system and reduce cost, and to explore the use of saliva sampling as an alternative to blood sampling. Subjects received an oral dose (133 micrograms) of 43Ca and an i.v. dose (7.7 micrograms) of 46Ca. Isotopic enrichment in blood, urine, saliva and feces was well above thermal ionization mass spectrometry measurement precision up to 170 h after dosing. Fractional calcium absorptions determined from isotopic ratios in blood, urine and saliva were similar. Compartmental modeling revealed that kinetic parameters determined from serum or saliva data were similar, decreasing the necessity for blood samples. It is concluded from these results that calcium kinetics can be assessed with micrograms doses of stable isotopes, thereby reducing tracer costs and with saliva samples, thereby reducing the amount of blood needed.

  16. Stable Isotope Laser Spectrometer for Exploration of Mars

    NASA Technical Reports Server (NTRS)

    Sauke, Todd B.; Becker, Joseph F.

    1998-01-01

    On Earth, measurements of the ratios of stable carbon isotopes have providet much information about geological and biological processes. For example, fractionation of carbon occur in biotic processes and the retention of a distinctive 2-4% contrast in C-13/C-12 between organic carbon and carbonates in rocks as old as 3.8 billion years constitutes some of the firmest evidence for the antiquity of life on the Earth. We have developed a prototype tunable diode laser spectrometer which demonstrates the feasibility of making accurate in situ isotopic ratio measurements on Mars. This miniaturized instrument, with an optical path length of 10 cm should be capable of making accurate C-13/C-12 and N-15/N-14 measurements. Gas samples for measurement are to be produced by pyrolysis using soil samples as small as 50 mg. Measurements of C-13/C-12, O-18/O-16 and N-15/N-14 have been made to a precision of better than 0.1%, and various other isotopes are feasible. This laser technique, which relies on the extremely narrow emission linewidth of tunable diode lasers (less than 0.001/ cm),has favorable features in comparison to mass spectrometry, the standard method of accurate isotopic ratio measurement. The miniature instrument could be ready to deploy c 2003 or other Mars lander missions.

  17. Assessing sources of human methylmercury exposure using stable mercury isotopes.

    PubMed

    Li, Miling; Sherman, Laura S; Blum, Joel D; Grandjean, Philippe; Mikkelsen, Bjarni; Weihe, Pál; Sunderland, Elsie M; Shine, James P

    2014-01-01

    Seafood consumption is the primary route of methylmercury (MeHg) exposure for most populations. Inherent uncertainties in dietary survey data point to the need for an empirical tool to confirm exposure sources. We therefore explore the utility of Hg stable isotope ratios in human hair as a new method for discerning MeHg exposure sources. We characterized Hg isotope fractionation between humans and their diets using hair samples from Faroese whalers exposed to MeHg predominantly from pilot whales. We observed an increase of 1.75‰ in ?(202)Hg values between pilot whale muscle tissue and Faroese whalers' hair but no mass-independent fractionation. We found a similar offset in ?(202)Hg between consumed seafood and hair samples from Gulf of Mexico recreational anglers who are exposed to lower levels of MeHg from a variety of seafood sources. An isotope mixing model was used to estimate individual MeHg exposure sources and confirmed that both ?(199)Hg and ?(202)Hg values in human hair can help identify dietary MeHg sources. Variability in isotopic signatures among coastal fish consumers in the Gulf of Mexico likely reflects both differences in environmental sources of MeHg to coastal fish and uncertainty in dietary recall data. Additional data are needed to fully refine this approach for individuals with complex seafood consumption patterns. PMID:24967674

  18. Assessing Sources of Human Methylmercury Exposure Using Stable Mercury Isotopes

    PubMed Central

    2015-01-01

    Seafood consumption is the primary route of methylmercury (MeHg) exposure for most populations. Inherent uncertainties in dietary survey data point to the need for an empirical tool to confirm exposure sources. We therefore explore the utility of Hg stable isotope ratios in human hair as a new method for discerning MeHg exposure sources. We characterized Hg isotope fractionation between humans and their diets using hair samples from Faroese whalers exposed to MeHg predominantly from pilot whales. We observed an increase of 1.75‰ in ?202Hg values between pilot whale muscle tissue and Faroese whalers’ hair but no mass-independent fractionation. We found a similar offset in ?202Hg between consumed seafood and hair samples from Gulf of Mexico recreational anglers who are exposed to lower levels of MeHg from a variety of seafood sources. An isotope mixing model was used to estimate individual MeHg exposure sources and confirmed that both ?199Hg and ?202Hg values in human hair can help identify dietary MeHg sources. Variability in isotopic signatures among coastal fish consumers in the Gulf of Mexico likely reflects both differences in environmental sources of MeHg to coastal fish and uncertainty in dietary recall data. Additional data are needed to fully refine this approach for individuals with complex seafood consumption patterns. PMID:24967674

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 (PLFA) were studied in a survey of 22 North American oligotrophic to eutrophic lakes. The ?13C of different PLFA 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 ?13C of DIC. All organic-carbon pools showed larger isotopic variability in eutrophic lakes compared to oligo-mesotrophic lakes because of the high variability in ?13C at the base of the food web (both autochthonous and allochthonous carbon). Phytoplankton ?13C 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.

  20. Stable isotopes determination in some Romanian fruit juices.

    PubMed

    Magdas, Dana Alina; Puscas, Romulus

    2011-09-01

    The characterisation of 45 Romanian single-strength fruit juices (apples, pears, plums and grapes) collected from different Transylvanian areas by means of stable isotope approach are presented and discussed in this study. We measured (2)H/(1)H, (18)O/(16)O ratios from water juice and (13)C/(12)C from pulp and compared these results with those already reported in the literature for single-strength juices, in order to see how the geographical and climatic conditions of Transylvania and the meteorological peculiarities of the year 2010 influence the isotopic composition of the investigated fruit juices. The ?(13)C mean values that we found for apple pulp picked up from different Transylvanian areas show slight differences, probably due to the environmental conditions of the plants. No significant correlation either between the variety of apple or the geographical origin and ?(13)C value was established. PMID:21892892

  1. Using phylogenetic probes for quantification of stable isotope labeling and microbial community analysis

    DOEpatents

    Brodie, Eoin L; DeSantis, Todd Z; Karaoz, Ulas; Andersen, Gary L

    2014-12-09

    Herein is described methods for a high-sensitivity means to measure the incorporation of stable isotope labeled substrates into RNA following stable isotope probing experiments (SIP). RNA is hybridized to a set of probes such as phylogenetic microarrays and isotope incorporation is quantified such as by secondary ion mass spectrometer imaging (NanoSIMS).

  2. 2nd Owl Symposium You Are What You Eat: Stable Isotope Ecology

    E-print Network

    2nd Owl Symposium You Are What You Eat: Stable Isotope Ecology of Owl Diets in Alberta, Canada Jason M. Duxbury and Geoffrey L. Holroyd1 Abstract.--Stable isotope ratio analysis (SIRA) was used that differed significantly from that of the Great Horned Owl. Great Horned Owl had the most diverse isotope

  3. Novel stable-isotope proxies in stalagmites to reconstruct the past Supervisors: Prof. Gideon Henderson

    E-print Network

    Henderson, Gideon

    .M. Henderson (2003) Lithium-isotope fractionation during continental weathering processes. Earth and PlanetaryNovel stable-isotope proxies in stalagmites to reconstruct the past Supervisors: Prof. Gideon-environmental reconstruction. Stable-isotope variation of metals such as Li, Ca, and Mg appear to contain useful information

  4. Stable carbon and oxygen isotope fractionation in bivalve (Placopecten magellanicus) larval aragonite

    E-print Network

    Schöne, Bernd R.

    Stable carbon and oxygen isotope fractionation in bivalve (Placopecten magellanicus) larval depleted from oxygen isotope equilibrium. Further studies are nec- essary to determine the variable The relationship between stable isotope composition (d13 C and d18 O) in seawater and in larval shell aragonite

  5. Stable isotope models to predict geographic origin and cultivation conditions of marijuana

    E-print Network

    Ehleringer, Jim

    Stable isotope models to predict geographic origin and cultivation conditions of marijuana Janet M: Marijuana Geographic origin Drug trafficking Drug intelligence Stable isotopes Isotope ratio mass geographic region-of-origin and growth environment for marijuana, with the intent of applying these models

  6. The role of stable isotopes and mercury concentrations to describe seabird foraging ecology in tropical environments

    E-print Network

    Boyer, Edmond

    1 The role of stable isotopes and mercury concentrations to describe seabird foraging ecology;2 Abstract: Nitrogen (15 N) and carbon (13 C) stable isotopes and contaminants, such as mercury, have been, for the first time, we used isotopic signatures and mercury levels of feathers and blood of eight tropical

  7. Characterization of phenols biodegradation by compound specific stable isotope analysis

    NASA Astrophysics Data System (ADS)

    Wei, Xi; Gilevska, Tetyana; Wenzig, Felix; Hans, Richnow; Vogt, Carsten

    2015-04-01

    Biodegradation of phenol and alkylphenols has been described under both oxic and anoxic conditions. In the absence of molecular oxygen, the degradation of phenolic compounds is initiated by microorganisms through carboxylation, fumarate addition to the methyl moiety or anoxic hydroxylation of the methyl moiety. Comparatively, under aerobic condition, the initiation mechanisms are revealed to be monoxygenation or dihydroxylation for phenol and ring hydroxylation or methyl group oxidation for cresols. While several studies biochemically characterized the enzymes and reaction mechanisms in the relevant degradation pathways, isotope fractionation patterns were rarely reported possibly due to constraints in current analytical methods. In this study, the carbon isotope fractionation patterns upon the degradation of phenol and cresols by several strains were analyzed by using isotope ratio mass spectrometry connected with liquid chromatography (LC-IRMS). The corresponding enrichment factors for carbon (?C) have been obtained. Cresols degradation by various strains showed generally moderate carbon isotope fractionation patterns with notable differences. For p-cresol degradation, five strains were examined. The aerobic strain Acinetobacter calcoaceticus NCIMB8250 exploits ring hydroxylation by molecular oxygen as initial reaction, and a ?C value of -1.4±0.2‰ was obtained. Pseudomonas pseudoalcaligenes NCIMB 9867, an aerobic strain initiating cresols degradation via oxygen-dependent side chain hydroxylation, yielded a ?C value of -2.3±0.2‰. Under nitrate-reducing conditions, Geobacter metallireducens DSM 7210 and Azoarcus buckelii DSM 14744 attacks p-cresol at the side chain by monohydroxylation using water as oxygen source; the two strains produced ?C values of -3.6±0.4‰ and -2±0.1‰, accordingly. The sulfate-reducing Desulfosarcina cetonica DSM 7267 activating cresols by fumarate addition to the methyl moiety yielded ?C values of -1.9±0.2‰ for p-cresol degradation and 2.2±0.3‰ for m-cresol degradation, respectively. The carbon isotope fractionation patterns of phenol degradation differed more profoundly. Oxygen-dependent monooxygenation of phenol by A.calcoaceticus as the initial reaction yielded ?C values of -1.5±0.02‰. In contrast, the anaerobic degradation initiated by ATP-dependent carboxylation performed by Thauera aromatia DSM 6984, produced no detectable fractionation (?C 0±0.1‰). D. cetonica showed a slight inverse carbon isotope fractionation (?C 0.4±0.1‰). In conclusion, a validated method for compound specific stable isotope analysis was developed for phenolic compounds, and the first data set of carbon enrichment factors upon the biodegradation of phenol and cresols with different activation mechanisms has been obtained in the present study. Carbon isotope fractionation analysis is a potentially powerful tool to monitor phenolic compounds degradation in the environment.

  8. Trophic position of deep-sea fish—Assessment through fatty acid and stable isotope analyses

    NASA Astrophysics Data System (ADS)

    Stowasser, G.; McAllen, R.; Pierce, G. J.; Collins, M. A.; Moffat, C. F.; Priede, I. G.; Pond, D. W.

    2009-05-01

    To investigate the trophic ecology of two of the dominant families of deep-sea fish (Macrouridae and Moridae) fatty acid and stable isotope analyses were applied to liver and muscle samples of five abundant species from the NE Atlantic. In conjunction with stomach content data these methods made it possible to identify differences in feeding strategies between the five study species as well as variation in feeding in relation to increasing depth and body size. Biomarkers identified strong similarities between Coryphaenoides armatus and Antimora rostrata though differences were found associating C. armatus more with the benthic food web whereas A. rostrata showed stronger links to the pelagic food web. While Lepidion eques was classified as a species linking benthic and benthopelagic food webs, both fatty acid and stable isotope data suggested that Coryphaenoides guentheri fed on an exclusively benthic diet . Coryphaenoides rupestris on the other hand were largely dependent on a copepod-based food web. Ontogenetic changes in feeding were found for both A. rostrata and C. armatus with the indication of a switch from active predation to scavenging occurring with increasing body size. Biomarkers also reflected the seasonal influx from the photic zone though changes were species-specific and probably reflected the variation in prey availability and abundance in response to these inputs. Our findings have thus demonstrated that the combined use of these biomarkers can elucidate trophic specialisations in situations where conventional methods alone previously provided insufficient data.

  9. High-precision measurement of chlorine stable isotope ratios

    USGS Publications Warehouse

    Long, A.; Eastoe, C.J.; Kaufmann, R.S.; Martin, J.G.; Wirt, L.; Finley, J.B.

    1993-01-01

    We present an analysis procedure that allows stable isotopes of chlorine to be analyzed with precision sufficient for geological and hydrological studies. The total analytical precision is ?????0.09%., and the present known range of chloride in the surface and near-surface environment is 3.5???. As Cl- is essentially nonreactive in natural aquatic environments, it is a conservative tracer and its ??37Cl is also conservative. Thus, the ??37Cl parameter is valuable for quantitative evaluation of mixing of different sources of chloride in brines and aquifers. ?? 1993.

  10. Otolith chemistry, stomach contents and stable isotope analysis of a snapper (Pagrus auratus) caught in the Waikato River

    E-print Network

    Waikato, University of

    Otolith chemistry, stomach contents and stable isotope analysis of a snapper (Pagrus auratus .....................................................................................................................................6 Stomach contents

  11. A standard protocol for stable isotope analysis of zooplankton in aquatic food web research using mass balance correction models

    Microsoft Academic Search

    Peter M. Smyntek; Mark A. Teece; Kimberly L. Schulz; Stephen J. Thackeray

    2007-01-01

    Stable isotope analysis has become a crucial tool for aquatic food web ecologists, but a lack of methodological standardization hinders comparisons between studies. One methodological inconsistency in stable isotope food web research is the decision whether to extract lipids before stable isotope analysis. The depletion in zooplankton stable carbon isotope values (d13C) due to fatty acid content and the accuracy

  12. Trophic ecology of the armadillo ant, Tatuidris tatusia, assessed by stable isotopes and behavioral observations.

    PubMed

    Jacquemin, Justine; Delsinne, Thibaut; Maraun, Mark; Leponce, Maurice

    2014-01-01

    Ants of the genus Tatuidris Brown and Kempf (Formicidae: Agroecomyrmecinae) generally occur at low abundances in forests of Central and South America. Their morphological peculiarities, such as mandibular brushes, are presumably linked with specialized predatory habits. Our aims were to (1) assess the Tatuidris abundance in an evergreen premontane forest of Ecuador; (2) detail morphological characteristics and feeding behavior of Tatuidris; and (3) define the position of Tatuidris in the food web. A total of 465 litter samples were collected. For the first time, live Tatuidris individuals were observed. Various potential food sources were offered to them. A nitrogen stable isotope ratio analysis ((15)N/(14)N) was conducted on Tatuidris tatusia, other ants, and common organisms from the leaf-litter mesofauna. We found a relatively high abundance of T. tatusia in the site. Live individuals did not feed on any of the food sources offered, as usually observed with diet specialist ants. The isotope analysis revealed that T. tatusia is one of the top predators of the leaf-litter food web. PMID:25199767

  13. Stable isotope studies. Final report, March 1, 1972--February 29, 1992

    SciTech Connect

    Ishida, T.

    1992-10-01

    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.

  14. Stable isotope fractionation by thermal diffusion through partially molten wet and dry silicate rocks

    E-print Network

    Bindeman, Ilya N.

    Stable isotope fractionation by thermal diffusion through partially molten wet and dry silicate 2012 Editor: T.M. Harrison Keywords: thermal diffusion hydrogen isotope separation oxygen isotopes lithium isotopes 17-O meteoric hydrothermal systems a b s t r a c t Water plays a fundamental role

  15. Non-biological fractionation of stable Ca isotopes in soils of the Atacama Desert, Chile

    E-print Network

    Amundson, Ronald

    Non-biological fractionation of stable Ca isotopes in soils of the Atacama Desert, Chile Stephanie elements over time, or (b) isotopic fractionation of all three elements during downward transport. We.4 in CaSO4. The overall depth trend in Ca isotopes is reproduced by a model of isotopic fractionation

  16. Application of Stable Isotope Tracers to Determine Latent Heat Exchange in Stable and Condensing Boundary Layers

    NASA Astrophysics Data System (ADS)

    Noone, D. C.; Raudzens Bailey, A.; Berkelhammer, M. B.; Cox, C.; Kaushik, A.

    2014-12-01

    Understanding the manner in which material is exchanged between the planetary boundary layer and the free troposphere is essential for evaluating many aspects of climate, including the distribution of trace gases, the transport of energy and water, cloud types, climate sensitivity, and the surface energy balance. However, neither observations nor parameterized numerical models constrain the interplay between moist processes and joint exchanges of water and heat adequately. Advance in understanding is limited in part by the complex controls on turbulence and, in the case of cloudy boundary layers, the interplay between turbulent mixing and latent heating, which is difficult to observe. Recent theoretical and observational advances now allow stable isotope ratios of water vapor and cloud condensate to be used to isolate the transport component from other thermodynamic controls, including condensation. Here we expose the role of latent heat exchanges that would be difficult to determine without a method to track water vapor transport. Analysis of case of a very stable boundary layer shows sustained downward latent heat fluxes during the development of a radiative inversion, and which establishes a new basis for parameterizing turbulence under stable conditions. The case of a capped convective marine boundary layer highlights the role of transport processes and condensation, which are critical for maintaining the temperature and humidity structure of the lower atmosphere over tropical oceans. While a variety of trace gases can be used to identify air mass exchange, water stable isotope ratios are particularly useful because they can identify latent heat exchanges, which are necessary to fully account for the coupling of water and energy in the boundary layer. The use of isotopic tracers explicitly captures this coupling even in the case of weak turbulence when important terms needed to resolve the local energy balance would otherwise be lost.

  17. Predicting Hydrogen and Oxygen Stable Isotope Ratios of Plants Across Terrestrial Surfaces: Plant IsoScapes

    NASA Astrophysics Data System (ADS)

    West, J. B.; Bowen, G. J.; Ehleringer, J. R.

    2005-12-01

    Human activities at local and regional scales impact the functioning of ecological processes. Integrating these activities requires spatially-explicit models that depend on both accurate input data, as well as a mechanistic understanding of the processes being modeled. Stable isotope ratios of several elements have been used successfully as both recorders of ecological processes, and tracers of the cycling and movement of elements through the biosphere. As such they have the potential to yield useful information across multiple scales. ISOSCAPES is an effort to link ecological and physiological process models with geographic information systems in order to make and test spatially explicit predictions of stable isotope ratios for components of the biosphere. In addition to current ecological processes, we are also applying our understanding of spatial variations in isotope abundances to improve paleoclimatic and modern forensic reconstructions. We present results of our spatial predictions of ?2H and ?18O values for major plant components across the terrestrial surface of the Earth. Predictions for leaf water and cotton-boll cellulose were based on a mechanistic model of leaf water enrichment and biochemical fractionations associated with cellulose formation. The model was driven spatially with globally gridded climate normals obtained from the Climate Research Unit at the University of East Anglia, and globally gridded maps of source water isotope ratios. In addition to leaf water and cellulose, we present spatial predictions for the isotopic ratios of other plant components (e.g., seed lipids). The maps revealed significant latitudinal and continental variation that was consistent with expectations and the relatively limited spatially-explicit available data. Finally, we discuss the implications of these variations and future avenues of spatial-ecology research.

  18. Protein Stable Isotope Fingerprinting (P-SIF): Multidimensional Protein Chromatography Coupled to Stable Isotope-Ratio Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Pearson, A.; Bovee, R. J.; Mohr, W.; Tang, T.

    2012-12-01

    As metagenomics increases our insight into microbial community diversity and metabolic potential, new approaches are required to determine the biogeochemical expression of this potential within ecosystems. Because stable isotopic analysis of the major bioactive elements (C, N) has been used historically to map flows of substrates and energy among macroscopic food webs, similar principles may apply to microbes. To address this challenge, we have developed a new analytical approach called Protein Stable Isotope Fingerprinting (P-SIF). P-SIF generates natural stable isotopic fingerprints of microbial individual or community proteomes. The main advantage of P-SIF is the potential to bridge the gap between diversity and function, thereby providing a window into the "black box" of environmental microbiology and helping to decipher the roles of uncultivated species. Our method implements a three-way, orthogonal scheme to separate mixtures of whole proteins into subfractions dominated by single or closely-related proteins. Protein extracts first are isoelectrically focused in a gel-free technique that yields 12 fractions separated over a gradient of pH 3-10. Each fraction then is separated by size-exclusion chromatography into 20 pools, ranging from >100kD to ~10kD. Finally, each of these pools is subjected to HPLC and collected in 40 time-slices based on protein hydrophobicity. Theoretical calculation reveals that the true chromatographic resolution of the total scheme is 5000, somewhat less than the 9600 resulting fractions. High-yielding fractions are subjected to ?13C analysis by spooling-wire microcombustion irMS (SWiM-irMS) optimized for samples containing 1-5 nmol carbon. Here we will present the method, results for a variety of pure cultures, and preliminary data for a sample of mixed environmental proteins. The data show the promise of this method for unraveling the metabolic complexity hidden within microbial communities.

  19. The biogeochemistry, stable isotope geochemistry, and microbial community structure of a temperate intertidal mud#at: an integrated study

    Microsoft Academic Search

    Britta Hespenheide; Enrique Llobet-Brossa; Christine Beardsley; Ole Larsen; Andreas Schramm; Andrea Wieland; Max Planck

    An integrated study, combining biogeochemical, stable isotope, micro-sensor, sedimentologi- cal, phase-analytical, and molecular ecological methods, was carried out in April 1998 in a temperate intertidal mud#at (Site Dangast; German Wadden Sea of the southern North Sea). The biogeochemical zonation was investigated in relation to the vertical abundance of total and sulfate-reducing bacteria, crustaceans, nematodes, #agellates, and ciliates. Total organic carbon

  20. Geographical Patterns of Human Diet Derived from Stable-Isotope Analysis of Fingernails

    E-print Network

    Ehleringer, Jim

    , Sa~o Paulo, Brazil 2 Stable Isotope and Tritium Laboratories, US Geological Survey, Menlo Park to which these isotopic signatures remain distinct for peo- ple eating both omnivorous and vegetarian diets

  1. STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS (URUGUAY)

    EPA Science Inventory

    Stable isotopes are increasingly being used as tracers in ecological studies. One application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include pollution sources for air or water bodies, food sources for animals, ...

  2. Subcutaneous infusion and capillary "finger stick" sampling of stable isotope tracer in metabolic studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metabolic studies utilizing stable isotope tracer in humans have typically used intravenous tracer infusions and venous blood sampling. These studies explore subcutaneous infusion of isotope and "finger stick" capillary blood sampling to measure glucose turnover. Five subjects received simultaneous ...

  3. A quantitative approach to combine sources in stable isotope mixing models

    EPA Science Inventory

    Stable isotope mixing models, used to estimate source contributions to a mixture, typically yield highly uncertain estimates when there are many sources and relatively few isotope elements. Previously, ecologists have either accepted the uncertain contribution estimates for indiv...

  4. COMPOUND-SPECIFIC STABLE ISOTOPE ANALYSIS TO DEMONSTRATE IN-SITU MTBE BIOTRANSFORMATION

    EPA Science Inventory

    Change of stable isotope composition of organic contaminants (isotopic fractionation) is a useful indicator of biotransformation. Most of applications to date are in the area of chlorinated solvents and recently BTEX, MTBE and TBA. Chemical reactions (biotic- and abiotic transfor...

  5. COMPOUND-SPECIFIC STABLE ISOTOPE ANALYSIS TO DEMONSTRATE IN-SITU MTBE BIOTRANSFORMATION

    EPA Science Inventory

    Changes in the stable isotopic composition of organic contaminants (isotopic fractionation) are a useful indicator of biotransformation, and have been reported in literature for several volatile organic compounds. The technique offers an interesting alternative to time-consuming ...

  6. Dynamic simulation of stable water isotopes during the last interglacial

    NASA Astrophysics Data System (ADS)

    Gierz, P.; Lohmann, G.; Brocas, W.; Felis, T.

    2014-12-01

    Using the novel isotope module of the global fully coupled climate model COSMOS, we simulate the climate of the last interglacial for three time slices at 120, 125, and 130 kiloyears before present. The inclusion of stable water isotopes allows us to not only have a comprehensive picture of the climate state during a warm interglacial, but also allows for a direct comparison with climate proxy records. We compare our simulation with isotope data gathered from fossilized corals, which have an excellent temporal resolution and well constrained dating. A model data comparison allows us to see that there was an enhanced seasonality of both temperature and rainfall during the Eemian. While the data tends to produce a stronger winter cooling than the model, we suggest that this may be due to an incomplete climatology, as the measurements taken from the coral only encompasses a few decades. If the data happens to fall during an usually cool decade, the mismatch could be rectified. Alternatively, the data may include the cooling signal associated with centennial scale cold stadials during the Eemian. We test this by performing a freshwater perturbation experiment during the peak interglacial, which causes a pronounced cooling at the core site while the ocean circulation is depressed.

  7. Stable isotopes in collagen and Late Quaternary carnivore palaeoecology

    NASA Astrophysics Data System (ADS)

    Bocherens, Hervé

    2010-05-01

    Several taxa of large carnivores co-occurred during the late Pleistocene in the steppe-tundra ecosystem, such as wolf Canis lupus, cave lion Panthera leo spelaea, cave hyaena Crocuta crocuta spelaea, brown bear Ursus arctos and cave bear Ursus spelaeus and Ursus ingressus. This abundance of taxa belonging to the same guild raises questions about niche partitioning, especially in terms of dietary specialization and prey selection. Observations of the dietary ecology of the extant relatives of these late Pleistocene carnivores does not provide unambiguous answers as these populations live under very different environmental conditions where other potential prey species are present, but it appears that most of these modern large carnivores are relatively flexible in their prey selection. Palaeontological investigations dealing with faunal associations and activity marks on fossil bones also have their limitations, such as taphonomic biases (palimpsests rather than biological associations) and do not allow the quantification of consumption of various preys. In contrast, carbon and nitrogen isotopic signatures of bone collagen depend directly on those of the average diet. Since different potential prey species occurring in the steppe-tundra exhibit consistent isotopic differences for these chemical elements, it is possible to relate the carbon and nitrogen isotopic signatures measured in fossil carnivores with the preferential consumption of some prey species. Some amount of quantification can be provided using modified versions of mixing models developed for modern ecosystems. In addition, this isotopic approach is individual-based and it is therefore possible to investigate intra- and inter-population differences in prey selection, as well as possible chronological trends and differences linked to genetic differences by combining isotopic and ancient DNA studies on the same material. The isotopic approach has already shown that among the tested large carnivores, cave bears of various genetic types are overwhelmingly vegetarian while coeval brown bears are essentially carnivores, cave lions have a marked preference for reindeer, and none of the large carnivores match Neanderthals in terms of megaherbivore consumption (i.e. woolly mammoth and woolly rhinoceros).

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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. Our results obtained from ?13C 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.

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

    NASA Astrophysics Data System (ADS)

    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 ?13C 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  11. Subterranean Sympatry: An Investigation into Diet Using Stable Isotope Analysis

    PubMed Central

    Robb, Gillian N.; Woodborne, Stephan; Bennett, Nigel C.

    2012-01-01

    In the Western Cape three species of mole-rat occur in sympatry, however, little is known about differences in their dietary preferences. Dietary composition of the three species; the common mole-rat (Cryptomys hottentotus hottentotus), the Cape mole-rat (Georychus capensis) and the Cape dune mole-rat (Bathyergus suillus) were examined using stable isotope analysis. Blood, fur and claw samples were collected from 70 mole-rats, in addition to several potential food items, to assess food selection of the three species under natural conditions. Overall there was a significant difference in the isotopic composition (?13C and ?15N) between all three species and significant differences in their diet composition. There were also significant differences between tissues in all three species suggesting temporal variation in diet. The small size and colonial lifestyle of C. h. hottentotus allows it to feed almost 100% on bulbs, while the solitary and larger species G. capensis and B. suillus fed to a greater extent on other resources such as grasses and clover. B. suillus, the largest of the species, had the most generalized diet. However, overall all species relied most heavily upon geophytes and consumed the same species suggesting competition for resources could exist. We also showed a high level of individual variation in diet choices. This was most pronounced in B. suillus and G. capensis and less so in C. h. hottentotus. We demonstrate that stable isotope analysis can successfully be applied to examine dietary patterns in subterranean mammals and provide insights into foraging patterns and dietary variation at both the inter and intra population level. PMID:23139795

  12. Stable carbon isotope ratios in Asian elephant collagen: implications for dietary studies

    Microsoft Academic Search

    R. Sukumar; R. Ramesh

    1992-01-01

    Summary  Stable carbon isotope ratios in bone collagen have been used in a variety of dietary studies in modern and fossil animals,\\u000a including humans. Inherent in the stable isotope technique is the assumption that the isotopic signature is a reflection of\\u000a the diet and is persistent in collagen because this is a relatively inert protein. Carbon isotope analyses of bones from

  13. Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology

    Microsoft Academic Search

    Jeffrey F. Kelly

    2000-01-01

    Differential fractionation of stable isotopes of carbon during photosynthesis causes C 4 plants and C3 plants to have distinct carbon-isotope signatures. In addition, marine C 3 plants have stable-isotope ratios of carbon that are intermediate between C4 and terrestrial C3 plants. The direct incorporation of the carbon-isotope ratio ( 13C\\/12C) of plants into consumers' tissues makes this ratio useful in

  14. Stable Isotopic Constraints of the Turpan Basin in Northwestern China

    NASA Astrophysics Data System (ADS)

    Schaen, A. J.

    2010-12-01

    Stable isotopic analysis of sedimentary rocks can be used to reconstruct past geologic changes in the elevation and climate of topographic features such as mountain ranges and plateaus. The Tibetan Plateau is an ideal field laboratory for conducting this type of study because of the Plateau’s extreme topographic relief and relatively recent geologic growth. Here we present oxygen and carbon isotope compositions from a suite of sedimentary rock samples taken from the western Turpan Basin in northwestern China. This area of the basin collects sediment from weathering and erosion of the Bogda Shan located to the north. The goal of this study is to analyze changes in the stable isotope composition as a function of stratigraphic position to reconstruct paleoelevations and paleoclimates in this part of the Tibetan Plateau. The sedimentary rock samples analyzed in this study are Late Jurassic to Neogene age and are primarily mudstone, siltstone, fine sandstone along with lesser limestone. Samples were powered and then dissolved with phosphoric acid at 72?C. The liberated CO2 gas was then analyzed using a Finnigan Delta Plus XL mass spectrometer with a gasbench inlet system. Oxygen isotope values range from -13.72 to -1.62‰ (PDB) and exhibit a large scale trend to more negative values toward the top of the stratigraphic sequence. Superimposed on this large scale trend are systematic variations in isotopic composition as a function of age. The most positive ?18O values occur at approximately 160, 115, 60, and 5 ma. Conversely, ?18O minima are observed at 150, 90, and 40 ma. ?13C values range from -10.69‰ to 1.40‰ (PDB). The most positive ?13C values (-4.3 to 1.4) occur from 120-160 ma. Younger samples display small scale variations with age with notable ?13C minima of -10.7, -14.7, and -7.6‰ at 108, 80, and 17 ma, respectively. The variable ?18O and positive ?13C values from the Jurassic (145-160 ma) are consistent with an arid climate and high atmospheric PCO2 levels during the warm Mesozoic Era. The overall decrease in ?18O values observed during the Cretaceous (145-65 ma) can be explained by the global climatic transition from a warm Mesozoic to a relatively cool Cenozoic Era. We take into account other possible influences on the isotopic record including detrital effects, diagensis, and evaporation, but infer the primary control on the isotopic records to be changes in climate during these time periods. Because the magnitude of oxygen isotope changes is consistent with that expected due to global climate change, we infer that there were not significant changes in the elevation of the Bogda Shan during this time period. This conclusion is also supported by the similar grain size/lithology (siltstone-finer grained sandstones) from bottom to top through the stratigraphic sequence, consistent with dormant topography prior to the Tertiary Period.

  15. Application Of Stable Isotope Analysis To Study Temporal Changes In Foraging Ecology In A Highly Endangered Amphibian

    PubMed Central

    Gillespie, J. Hayley

    2013-01-01

    Background Understanding dietary trends for endangered species may be essential to assessing the effects of ecological disturbances such as habitat modification, species introductions or global climate change. Documenting temporal variation in prey selection may also be crucial for understanding population dynamics. However, the rarity, secretive behaviours and obscure microhabitats of some endangered species can make direct foraging observations difficult or impossible. Furthermore, the lethality or invasiveness of some traditional methods of dietary analysis (e.g. gut contents analysis, gastric lavage) makes them inappropriate for such species. Stable isotope analysis facilitates non-lethal, indirect analysis of animal diet that has unrealized potential in the conservation of endangered organisms, particularly amphibians. Methodology/findings I determined proportional contributions of aquatic macroinvertebrate prey to the diet of an endangered aquatic salamander Eurycea sosorum over a two-year period using stable isotope analysis of 13/12C and 15/14N and the Bayesian stable isotope mixing model SIAR. I calculated Strauss’ dietary electivity indices by comparing these proportions with changing relative abundance of potential prey species through time. Stable isotope analyses revealed that a previously unknown prey item (soft-bodied planarian flatworms in the genus Dugesia) made up the majority of E. sosorum diet. Results also demonstrate that E. sosorum is an opportunistic forager capable of diet switching to include a greater proportion of alternative prey when Dugesia populations decline. There is also evidence of intra-population dietary variation. Conclusions/significance Effective application of stable isotope analysis can help circumvent two key limitations commonly experienced by researchers of endangered species: the inability to directly observe these species in nature and the invasiveness or lethality of traditional methods of dietary analysis. This study illustrates the feasibility of stable isotope analysis in identifying preferred prey species that can be used to guide conservation management of both wild and captive food sources for endangered species. PMID:23341920

  16. Characterization of ganoderma spore lipid by stable carbon isotope analysis: implications for authentication

    Microsoft Academic Search

    Xin Liu; Shi-Ping Xu; Jiang-Hai Wang; Jian-Ping Yuan; Lian-Xian Guo; Xin Li; Xiao-Ni Huang

    2007-01-01

    The ratios of stable carbon isotopes (13C\\/12C) of ganoderma fruiting body, ganoderma spore, ganoderma spore lipid (GSL) and individual fatty acids in GSL were determined\\u000a by gas chromatography–stable isotope ratio mass spectrometry and elemental analysis–stable isotope ratio mass spectrometry.\\u000a These values fall into a range from ?26.9 to ?23.3‰, suggesting that the cut log as the Ganoderma-cultivated substrate in Fujian,

  17. Characterization of ganoderma spore lipid by stable carbon isotope analysis: implications for authentication.

    PubMed

    Liu, Xin; Xu, Shi-Ping; Wang, Jiang-Hai; Yuan, Jian-Ping; Guo, Lian-Xian; Li, Xin; Huang, Xiao-Ni

    2007-06-01

    The ratios of stable carbon isotopes ((13)C/(12)C) of ganoderma fruiting body, ganoderma spore, ganoderma spore lipid (GSL) and individual fatty acids in GSL were determined by gas chromatography-stable isotope ratio mass spectrometry and elemental analysis-stable isotope ratio mass spectrometry. These values fall into a range from -26.9 to -23.3 per thousand, suggesting that the cut log as the Ganoderma-cultivated substrate in Fujian, China, may belong to C3 plants. Eighteen fatty acids were identified and their abundances measured by gas chromatography-mass spectrometry in the six GSL samples with C(16:0), C(18:0), C(18:1) and C(18:2) as major constituents, and C(16:1) is evidently enriched compared with the other edible vegetable oils. On the basis of the compositions of fatty acids and stable carbon isotopes in GSL, we have developed a novel method to detect the adulteration of GSL products with cheaper edible vegetable oils. An example of ideal blending between GSL and C4 or C3 vegetable oil is further provided to expound the discrimination procedures and corresponding sensitive indicators. Simultaneously, the carbon isotope fractionation in the biosynthesis of individual fatty acids was observed, revealing that the formation of C(18:0) from C(16:0) in ganodema spores had no conspicuous (13)C enrichment of +0.4 per thousand for Ganoderma sinensis spore and +0.1 per thousand for G. lucidum spore; the desaturation of C(18:0) to C(18:1) resulted in a distinct (13)C depletion of -1.4 per thousand for G. sinensis spore and -0.9 per thousand for G. lucidum spore; and the next desaturation from C(18:1) to C(18:2) displayed no evident (13)C fractionation of -0.1 per thousand for G. sinensis spore and -0.2 per thousand for G. lucidum spore. PMID:17447054

  18. Investigating the contribution of mussel N regeneration to coastal primary production using stable isotope tracers

    NASA Astrophysics Data System (ADS)

    Pather, S.; Altabet, M. A.; Pfister, C. A.; Post, D. M.

    2010-12-01

    Determining the sources, pathways and sinks of inorganic nitrogen is integral to our understanding of one of the main determinants of primary productivity in the marine environment. The current view of rocky shore productivity is that it is largely fuelled by ‘new’ inorganic nitrogen brought to surface waters by the physical process of upwelling. However, along the rocky shores of the Washington State outer coast, the high densities of mussels (Mytilus californianus) colonizing these shores produce significant quantities of ‘regenerated’ inorganic nitrogen in the form of ammonium, a preferred nitrogen source for primary production. In this study, we seek to determine to what extent regenerated nitrogen is responsible for fueling primary production in these environments. To this end, we employed stable isotope tracers (15NH4 and 15NO3) to track the pathway of inorganic nitrogen in several rocky shore tidepools over the course of half a tidal cycle. Half of all the pools contained mussels in their natural abundance, while half were mussel control pools in which most of the mussels had been physically removed. Discrete water and algal tissue samples were taken at several time points within the study period for mass spectrometric stable isotope analysis. Preliminary results show isotope dilution of tidepool ammonium in pools containing mussels over half a tidal cycle, due to continued ammonium production by mussels. Combined concentration data, regeneration rates as well as removal rates due to autotrophic uptake and/or microbially-mediated ammonium oxidation (nitrification) will be calculated. Isotopic analysis of algal tissue samples and of the other nitrogen pools will shed further light on the contribution of regenerated ammonium to tidepool biogeochemical cycling and ultimately to coastal primary production.

  19. Stable isotope analysis of carbon and nitrogen in angrites

    NASA Astrophysics Data System (ADS)

    Abernethy, F. A. J.; Verchovsky, A. B.; Starkey, N. A.; Anand, M.; Franchi, I. A.; Grady, Monica M.

    2013-09-01

    Angrites are a small group of ancient basaltic achondrites, notable for their unusual chemistry and extreme volatile depletion. No comprehensive study of indigenous light elements currently exists for the group. Measurement of the abundances and isotopic composition of carbon and nitrogen could provide information pertaining to the evolution of the angrite parent body. Bulk-sample stepped combustion analyses of five angrites and a glass separate from D'Orbigny were combined with earlier data and acid dissolution experiments of carbonates found in D'Orbigny to compile an inventory of indigenous carbon and nitrogen. Indigenous carbon combusted between 700 °C and 1200 °C, with abundances of 10-140 ppm and a mass-weighted ?13C of -25 to -20‰ with the exception of D'Orbigny (?13C approximately -5‰). Nitrogen was released at 850-1200 ºC, 1-20 ppm with a ?15N -3‰ to +4‰; again, D'Orbigny (?15N approximately +20 to +25‰) was an exception. We interpret these components as largely indigenous and decoupled; the carbon in graphitic or amorphous form, while the nitrogen is present as a dissolved component in the silicates. No relationship with the textural sub-classification of angrites is apparent. We suggest that the angrite parent body contains a reservoir of reduced carbon and thus may have undergone a change in redox conditions, although the timing and mechanism for this remain unclear.

  20. Holocene environmental fluctuations of Lake Bosten (Xinjiang, China) inferred from ostracods and stable isotopes

    NASA Astrophysics Data System (ADS)

    Mischke, S.

    2003-04-01

    Lake Bosten is an oligohaline lake in an intermontane basin of the Tianshan Mountains in northwestern China. The open-basin lake receives water from a large catchment area (56,000 km2) with the Kaidu River as its main tributary. A core of 9.25 m length was drilled at 6.25 m water depth in the southwestern part of the lake near the Kaidu river inflow. Sediments of the core contain authigenic carbonate materials, including calcitic shells of ostracods, charophyte-oogonia and stem incrustations. Five AMS-dating results provided the base to establish the chronology of the core which extends back to about 8.4 cal. ka BP. The majority of the ostracod taxa from the core may be classified into two different groups comprising littoral taxa (Cyclocypris ovum, Cypridopsis vidua, Darwinula stevensoni, Fabaeformiscandona hyalina, Herpetocypris chevreuxi, Heterocypris salina) and taxa reflecting profundal conditions (Candona neglecta, Cytherissa lacustris and Fabaeformiscandona caudata). Among these taxa, C. neglecta and D. stevensoni were the most abundant ostracod species providing more than 50 % of the fossil shells in most core samples. Where C. neglecta peaks D. stevensoni often shows minima abundances and vice versa. Stable isotope data derived from ostracod calcite display large variations throughout the core. d18O and d13C values vary over a range of 10 ‰ and 6.7 ‰ respectively. These large ranges may reflect that Lake Bosten responded like a semi-closed lake at least. Low lake levels inferred from species assemblages correspond to lowest d18O values thus indicating the influence of isotopically light river water at the core site and a low residence time and salinity. High d18O values correspond to higher abundances of Candona neglecta and low abundances of littoral taxa pointing towards deeper conditions, a higher distance of the core site from the river inflow, a higher residence time and corresponding salinity of the lake water. On the base of ostracod and stable isotope data deepest conditions occurred between 8.2 and 5.7 cal. ka BP, interrupted by a brief return to lower levels at about 7.2 cal. ka BP. Low levels were reconstructed in the following period between 5.7 and 5.1 cal. ka BP and between 4.4 and 4.2 cal. ka BP. Spells of shallow conditions were recorded at 3.9, 3.6, 2.7, 2.3 and 1.8 cal. ka BP and for a longer period between 1.4 and 0.6 cal. ka BP.

  1. ANALYSIS OF RICIN TOXIN PREPARATIONS FOR CARBOHYDRATE AND FATTY ACID ABUNDANCE AND ISOTOPE RATIO INFORMATION

    SciTech Connect

    Wunschel, David S.; Kreuzer-Martin, Helen W.; Antolick, Kathryn C.; Colburn, Heather A.; Moran, James J.; Melville, Angela M.

    2009-12-01

    This report describes method development and preliminary evaluation for analyzing castor samples for signatures of purifying ricin. Ricin purification from the source castor seeds is essentially a problem of protein purification using common biochemical methods. Indications of protein purification will likely manifest themselves as removal of the non-protein fractions of the seed. Two major, non-protein, types of biochemical constituents in the seed are the castor oil and various carbohydrates. The oil comprises roughly half the seed weight while the carbohydrate component comprises roughly half of the remaining “mash” left after oil and hull removal. Different castor oil and carbohydrate components can serve as indicators of specific toxin processing steps. Ricinoleic acid is a relatively unique fatty acid in nature and is the most abundant component of castor oil. The loss of ricinoleic acid indicates a step to remove oil from the seeds. The relative amounts of carbohydrates and carbohydrate-like compounds, including arabinose, xylose, myo-inositol fucose, rhamnose, glucosamine and mannose detected in the sample can also indicate specific processing steps. For instance, the differential loss of arabinose relative to mannose and N-acetyl glucosamine indicates enrichment for the protein fraction of the seed using protein precipitation. The methods developed in this project center on fatty acid and carbohydrate extraction from castor samples followed by derivatization to permit analysis by gas chromatography-mass spectrometry (GC-MS). Method descriptions herein include: the source and preparation of castor materials used for method evaluation, the equipment and description of procedure required for chemical derivatization, and the instrument parameters used in the analysis. Two types of derivatization methods describe analysis of carbohydrates and one procedure for analysis of fatty acids. Two types of GC-MS analysis is included in the method development, one employing a quadrupole MS system for compound identification and an isotope ratio MS for measuring the stable isotope ratios of deuterium and hydrogen (D/H) in fatty acids. Finally, the method for analyzing the compound abundance data is included. This study indicates that removal of ricinoleic acid is a conserved consequence of each processing step we tested. Furthermore, the stable isotope D/H ratio of ricinoleic acid distinguished between two of the three castor seed sources. Concentrations of arabinose, xylose, mannose, glucosamine and myo-inositol differentiated between crude or acetone extracted samples and samples produced by protein precipitation. Taken together these data illustrate the ability to distinguish between processes used to purify a ricin sample as well as potentially the source seeds.

  2. Stable isotope studies on geothermal gases from the eastern part of Büyük Menderes Graben (Turkey)

    NASA Astrophysics Data System (ADS)

    Wiersberg, T.; Grassa, F.; Suer, S.; Gulec, N.; Erzinger, J.; Parlaktuna, M.

    2012-12-01

    We report new stable isotope data (?13C, ?15N) from three production wells of the Kizildere geothermal field and from three moffettes from the adjacent Tekke Hamam geothermal field, situated in the eastern segment of the Büyük Menderes graben system (western Anatolia, Turkey). The data were discussed in the context of sources and provenance of N2, CO2 and CH4, as well as carbon isotope exchange and reservoir temperatures. ?13C values of CO2 fall in a narrow range with no systematic differences between both locations. The values suggest limestone as prime source of CO2, mixing with small and variable amounts of CO2 from other sources (organic-rich sediments, mantle CO2). In contrast, ?13C values of CH4 differ considerably between both sites and reveal an origin of methane from thermal degradation of organic matter. Computed temperatures from carbon isotope exchange between CO2 and CH4 are 30-50°C higher than measured reservoir temperatures at Tekke Hamam and >80°C higher at Kizildere, respectively. The carbon isotope disequilibrium is probably caused by mixing of gases from different sources (limestone, organic-rich sediments) and a relatively fast ascent of the volatiles. The higher temperature discrepancy at Kizildere can be explained by faster gas ascent through a drill well, compared to slower gas ascent through natural fractures and faults at Tekke Hamam. Air-corrected ?15N values fall between values suggested for a sedimentary source and the mantle, but are quite variable even for samples from the same location. Comprehensive discussion of the new data with noble gas isotopes and gas abundances from the same samples (Wiersberg et al., 2011) will help to quantify the contributions of gases from different sources and to characterize mixing and phase separation processes. Wiersberg et al. (2011), JVGR (208), p. 112-121

  3. Stable isotopes (?13C and ?15N) of organic matrix from coral skeleton

    PubMed Central

    Muscatine, Leonard; Goiran, Claire; Land, Lynton; Jaubert, Jean; Cuif, Jean-Pierre; Allemand, Denis

    2005-01-01

    The evolutionary success of reef-building corals in nutrient-poor tropical waters is attributed to endosymbiotic dinoflagellates. The algae release photosynthetic products to the coral animal cells, augment nutrient flux, and enhance the rate of coral calcification. Natural abundance of stable isotopes (?13C and ?18O) provides answers to modern and paleobiological questions about the effect of photosymbiosis on sources of carbon and oxygen in coral skeletal calcium carbonate. Here we compare 17 species of symbiotic and nonsymbiotic corals to determine whether evidence for photosymbiosis appears in stable isotopes (?13C and ?15N) of an organic skeletal compartment, the coral skeletal organic matrix (OM). Mean OM ?13C in symbiotic and nonsymbiotic corals was similar (-26.08‰ vs. -24.31‰), but mean OM ?15N was significantly depleted in 15N in the former (4.09‰) relative to the latter (12.28‰), indicating an effect of the algae on OM synthesis and revealing OM ?15N as a proxy for photosymbiosis. To answer an important paleobiological question about the origin of photosymbiosis in reef-building corals, we applied this proxy test to a fossil coral (Pachythecalis major) from the Triassic (240 million years ago) in which OM is preserved. Mean OM ?15N was 4.66‰, suggesting that P. major was photosymbiotic. The results show that symbiotic algae augment coral calcification by contributing to the synthesis of skeletal OM and that they may have done so as early as the Triassic. PMID:15671164

  4. The cosmic ray source abundance of CSi isotopes: Dependence upon nuclear interaction cross sections

    Microsoft Academic Search

    Guzik

    1993-01-01

    New measurements of the Galactic Cosmic Ray (GCR) isotopic composition in the charge range C to Si are now becoming available. The GCR source composition of these isotopes are particularly interesting as they are synthesized by a broad range of processes requiring very different astrophysical conditions. However, these source abundances are obtained from the GCR measurements only by unfolding the

  5. Simulations of water isotope abundances in the upper troposphere and lower stratosphere and implications

    E-print Network

    Gettelman, Andrew

    Simulations of water isotope abundances in the upper troposphere and lower stratosphere and implications for stratosphere troposphere exchange Andrew Gettelman National Center for Atmospheric Research in the Upper Troposphere and Lower Stratosphere (UT/LS). The model is able to reproduce the range of isotopic

  6. MetaProSIP: automated inference of stable isotope incorporation rates in proteins for functional metaproteomics.

    PubMed

    Sachsenberg, Timo; Herbst, Florian-Alexander; Taubert, Martin; Kermer, René; Jehmlich, Nico; von Bergen, Martin; Seifert, Jana; Kohlbacher, Oliver

    2015-02-01

    We propose a joint experimental and theoretical approach to the automated reconstruction of elemental fluxes in microbial communities. While stable isotope probing of proteins (protein-SIP) has been successfully applied to study interactions and elemental carbon and nitrogen fluxes, the volume and complexity of mass spectrometric data in protein-SIP experiments pose new challenges for data analysis. Together with a flexible experimental setup, the novel bioinformatics tool MetaProSIP offers an automated high-throughput solution for a wide range of (13)C or (15)N protein-SIP experiments with special emphasis on the analysis of metaproteomic experiments where differential labeling of organisms can occur. The information calculated in MetaProSIP includes the determination of multiple relative isotopic abundances, the labeling ratio between old and new synthesized proteins, and the shape of the isotopic distribution. These parameters define the metabolic capacities and dynamics within the investigated microbial culture. MetaProSIP features a high degree of reproducibility, reliability, and quality control reporting. The ability to embed into the OpenMS framework allows for flexible construction of custom-tailored workflows. Software and documentation are available under an open-source license at www.openms.de/MetaProSIP. PMID:25412983

  7. Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry

    USGS Publications Warehouse

    Meier, A.L.

    1982-01-01

    The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe the relationship of the absorption of 6Li and 7Li lamp radiation is proposed as a means of calculating isotopic composition that is independent of total lithium concentration.

  8. Applications, considerations, and sources of uncertainty when using stable isotope analysis in ecotoxicology.

    PubMed

    Jardine, Timothy D; Kidd, Karen A; Fisk, Aaron T

    2006-12-15

    Stable isotope analysis (SIA) has become a powerful tool for ecotoxicologists to study dietary exposure and biomagnification of contaminants in wild animal populations. The use of SIA in ecotoxicology continues to expand and, while much more is known about the mechanisms driving patterns of isotopic ratios in consumers, there remain several considerations or sources of uncertainty that can influence interpretation of data from field studies. We outline current uses of SIA in ecotoxicology, including estimating the importance of dietary sources of carbon and their application in biomagnification studies, and we present six main considerations or sources of uncertainty associated with the approach: (1) unequal diet-tissue stable isotope fractionation among species, (2) variable diet-tissue stable isotope fractionation within a given species, (3) different stable isotope ratios in different tissues of the animal, (4) fluctuating baseline stable isotope ratios across systems, (5) the presence of true omnivores, and (6) movement of animals and nutrients between food webs. Since these considerations or sources of uncertainty are difficult to assess in field studies, we advocate that researchers consider the following in designing ecotoxicological research and interpreting results: assess and utilize variation in stable isotope diet-tissue fractionation among animal groups available in the literature; determine stable isotope ratios in multiple tissues to provide a temporal assessment of feeding; adequately characterize baseline isotope ratios; utilize stomach contents when possible; and assess and integrate life history of study animals in a system. PMID:17256487

  9. Characterizing the Hydrologic Impacts of Mountaintop Mining Using Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Zegre, N.; McGuire, K. J.

    2011-12-01

    Despite mountaintop removal mining (MTM) accounting for the largest land-use change in the Appalachian region of the eastern US, its impact on runoff processes is poorly understood. Several devastating floods have been attributed to MTM activities upstream but there is little quantifiable evidence on how MTM impacts mechanisms of streamflow generation and flooding downstream. MTM involves removing the forest, topsoil, and overlying bedrock to gain access to deeper coal seams. Excess rock is pushed into adjacent valley to create valley fills that completely bury headwater streams that permanently alter ecosystem organization and processes. Isotope hydrology can provide process-based information about the temporal and geographic sources of runoff and rainfall-runoff relationships, but these approaches have not been applied in systems undergoing rapid change and typically not at larger landscape scales. In this study we examine runoff generation using stable isotopes of water from Sycamore Creek (27 km2), an undisturbed forested catchment, and White Oak Creek (11 km2), a MTM-impacted catchment, to quantify for the first time how landscape-scale disturbances impact rainfall-runoff relationship and the processes that govern runoff generation. Both catchments are headwaters of the Clear Fork River watershed (163 km2), an extensively mined and recurrent flood-prone watershed in southern West Virginia, USA. Mountaintop mining in White Oak Creek has disturbed 3 km2 (27% of catchment area) to include 10 valley fills comprising ~0.8 km2 (7%). Stream and rainfall were continuously measured at the outlet of each catchment and water samples were collected using Isco automated water samplers to incrementally characterize isotopic variations in 18O and 2H. Streamflow was separated into event and pre-event water using a two-component hydrograph separation model. The total fraction of event/pre-event water for each event was estimated by linear interpolation between incremental samples of stream and precipitation from the onset of precipitation until stream isotope values returned to pre-event levels. Incremental sampling allows us to estimate the total, peak, and temporal variations of event water contribution during storm events. Our results show that streamflow in White Oak Creek is primarily dominated by event water, whereas pre-event, older water dominates stormflow in the undisturbed Sycamore Creek catchment. We hypothesize that streamflow generation in White Oak Creek is dominated by infiltration-excess overland flow that rapidly delivers event water to the stream, compared to predominantly subsurface flow paths in Sycamore Creek. On-going research using geochemical characterization, end-member mixing analysis, and transit time modeling is aimed at quantifying how MTM impacts the stores, flow paths, and transit times of catchment water.

  10. Stable Carbon Isotopes As Indicators of Plant Water Use Efficiency

    NASA Astrophysics Data System (ADS)

    Powers, E. M.; Marshall, J. D.; Ubierna Lopez, N.

    2007-12-01

    Stable carbon isotopes have been utilized to better understand how environmental variables influence the efficiency of photosynthesis, specifically what factors limit the uptake and absorption of CO2 during photosynthesis. An understanding of the controls over both gas exchange and stomatal conductance can provide an explanation for the possible environmental influences on plant WUE. The ?13C of extractive-free wood was used as an index of plant water use efficiency at Mica Creek Experimental Watershed, Shoshone County, ID. The ?13C values of tree rings were used to determine the effects of clear cut and partial cut harvesting practices, the effect of elevation, and species differences in intrinsic water use efficiency (WUE) among coniferous species including: Thuja plicata, Larix occidentalis, Picea engelmannii, Pseudotsuga menziesii, Abies lasiocarpa, and Abies grandis. We found significant effects of harvest treatments (p=0.0197), elevation (p= 0.0268), and species (p<0.001) on tree ?13C. The significantly more enriched isotopic signatures observed in Thuja plicata (?13C = -23.37 ±0.17‰), indicate that it is a more water use efficient species compared to Larix occidentalis (?13C = -25.66 ±0.43‰), and Abies grandis (?13C = -25.83 ±0.15‰). There was also an overall trend of ?13C enrichment with elevation. The isotopic composition of tree rings has been estimated to increase by 0.003 ‰ per meter of elevation gain, which may be related to a decrease in soil moisture with elevation. Finally, the mean ?13C values observed on partial cut (?13C = -24.73 ±0.10‰) and clear cut treatments (?13C = -24.45 ±0.29‰) were significantly more enriched than the mean value for the control treatment (?13C = -25.25 ±0.19‰). The more enriched isotopic signatures observed on the harvested treatments indicate that the trees are more water use efficient, which may be a result of increased photosynthetic capacity with an increase in the availability of water, foliar nitrogen, and light to individual trees on the harvested treatments. The reduction of stand density through harvesting may reduce the transpirational water losses on a stand level, thus increasing the water availability for individual trees.

  11. A comparison of lignin and stable carbon isotope compositions in quaternary marine sediments

    Microsoft Academic Search

    JOHN I. HEDGES; ALEXANDER VAN GEEN

    1982-01-01

    Heges, J.I. and van Geen, A., 1982. A comparison of lignin and stable carbon isotope compositions in quaternary marine sediments. Mar. Chem., 11: 43--53. Organic matter in four Quaternary sediment cores from the Gulf of Mexico and one core from the Washington State coast have been analyzed for lignin and stable carbon isotope compositions. Holocene sequences of all five cores

  12. USING STABLE ISOTOPES FOR FISH DIETARY ANALYSES: COPING WITH TOO MANY SOURCES

    EPA Science Inventory

    Stable isotope analysis can provide a useful tool for determining time-integrated measures of proportional food source contributions to fish diets. Ratios of stable (non-radioactive) isotopes of common elements (e.g., C,N,S) vary among food sources, and tissues of consumers (e.g...

  13. Stable carbon and oxygen isotopes in sub-fossil Sphagnum: Assessment of their applicability for palaeoclimatology

    Microsoft Academic Search

    Robert Moschen; Norbert Kühl; Ingo Rehberger; Andreas Lücke

    2009-01-01

    To investigate the potential of stable isotopes of Sphagnum peat deposits for palaeoclimate research and to inform sampling strategies, we present results from a study of selected Sphagnum plant constituents. We report a combined stable carbon and oxygen isotope record of cellulose separately extracted from Sphagnum branches and stem sections manually sampled from a ?4000 year old peat, deposited in a

  14. Lipid Correction for Carbon Stable Isotope Analysis of Deep-sea Fishes

    EPA Science Inventory

    Lipid extraction is used prior to stable isotope analysis of fish tissues to remove variability in the carbon stable isotope ratio (d13C) caused by varying lipid content among samples. Our objective was to evaluate an application of a mass balance correction for the effect of lip...

  15. The fish of Lake Titicaca: implications for archaeology and changing ecology through stable isotope analysis

    Microsoft Academic Search

    Melanie J. Miller; José M. Capriles; Christine A. Hastorf

    2010-01-01

    Research on past human diets in the southern Lake Titicaca Basin has directed us to investigate the carbon and nitrogen stable isotopes of an important dietary element, fish. By completing a range of analyses on modern and archaeological fish remains, we contribute to two related issues regarding the application of stable isotope analysis of archaeological fish remains and in turn

  16. RADIOCARBON AND STABLE ISOTOPE ANALYSES OF ARCHAEOLOGICAL BONE CONSOLIDATED WITH HIDE GLUE

    Microsoft Academic Search

    C M Takahashi; D E Nelson

    We tested a simple method for removing a collagen-based glue preservative from bone destined for radiocar- bon and stable isotope analyses. The method is sufficient for bone samples from which only stable isotope measurements are required. For 14C dating, such samples of age less than about 10 ka can be adequately dated, but for older samples, the cir- Ancient bone

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

    Microsoft Academic Search

    Joel C. Hoffman; Tracey T. Sutton

    2010-01-01

    Stable isotope analysis of fish tissue can aid studies of deep-sea food webs because sampling difficulties severely limit sample sizes of fish for traditional diet studies. The carbon stable isotope ratio (?13C) is widely used in food web studies, but it must be corrected to remove variability associated with varying lipid content in the tissue. A lipid correction has not

  18. Stable isotopes in ecosystem science: structure, function and dynamics of a subtropical savanna

    Microsoft Academic Search

    T. W. Boutton; S. R. Archer; A. J. Midwood

    1999-01-01

    Stable isotopes are often utilized as intrinsic tracers to study the effects of human land uses on the structural and functional characteristics of ecosystems. Here, we illustrate how stable isotopes of H, C, and O have been utilized to document changes in ecosystem structure and function using a case study from a subtropical savanna ecosystem. Specifically, we demonstrate that: (1)

  19. Relationships between stable isotopes and metal contaminants in feathers are spurious and biologically uninformative

    E-print Network

    Jones, Ian L.

    Commentary Relationships between stable isotopes and metal contaminants in feathers are spurious in feathers are biologically uninformative because of the differences in integration times. a r t i c l e i n elements Mercury Feathers Ecotoxicology a b s t r a c t Stable isotopes of carbon (d13 C) and nitrogen (d15

  20. Carbon pathways to zooplankton: insights from the combined use of stable isotope and fatty acid biomarkers

    E-print Network

    Mazumder, Asit

    biomarkers MARIE-ELODIE PERGA,*, MARTIN KAINZ,*, BLAKE MATTHEWS* AND ASIT MAZUMDER* *Water and Watershed and stable isotope biomarkers could solve this issue. We conducted a field study on two oligotrophic lakes. This is the first study illustrating that the combination of fatty acid and stable isotope biomarkers could further

  1. Use of stable isotopically labeled tracers for studies of metabolic kinetics: An overview

    Microsoft Academic Search

    Bruce W. Patterson

    1997-01-01

    Stable isotopically labeled tracers offer a reliable and safe alternative to the use of radioactive tracers for studies of metabolic kinetics. This overview examines some of the principles and technical issues regarding mass spectrometry instrumentation, and reviews some of the approaches used in the application of stable isotopically labeled tracers to studies of protein, lipid, and carbohydrate metabolic kinetics.

  2. Bioavailability of xenobiotics in unsaturated soils – implications for nucleic acid based stable isotope probing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of stable isotopes to label phylogenetically informative biomolecules (phospholipid fatty acids, DNA, or RNA), typically referred to as stable isotope probing (SIP) has the potential of providing definitive evidence that a detected population is active in a specific process, if that process ...

  3. The contribution of insect prey to the total nitrogen content of sundews (Drosera spp.) determined in situ by stable isotope analysis

    Microsoft Academic Search

    Jonathan Millett; Roger I. Jones; Susan Waldron

    2003-01-01

    Summary • The contribution of insect prey to total N in the carnivorous plants, Drosera rotun- difolia and D. intermedia , was quantified in situ and without any experimental manipulation using natural abundance stable isotope analysis. • Samples of D. rotundifolia and D. intermedia , insects and noncarnivorous refer- ence plants were collected from three contrasting locations across Britain. The

  4. Fast or feast: reconstructing diet in later medieval England by stable isotope analysis

    Microsoft Academic Search

    Gundula Muldner; Michael P. Richards

    In this pilot-study, which was designed to assess the range of isotopic variation in English medieval populations, we present the results of stable isotope analysis of carbon and nitrogen of human and animal bone collagen from three later medieval sites in Northern England. The isotopic values observed for the rural hospital of St. Giles by Brompton Bridge (N. Yorks.), the

  5. Stable isotope ecology of the common hippopotamus T. E. Cerling1,2

    E-print Network

    Lewison, Rebecca

    Stable isotope ecology of the common hippopotamus T. E. Cerling1,2 , J. M. Harris3 , J. A. Hart4 Diego State University, San Diego, CA, USA Keywords carbon isotope ratio; diet; Hippopotamus amphibius; isotope ecology. Correspondence Thure E. Cerling, Department of Geology and Geophysics, University of Utah

  6. Caution on the Use of Liquid Nitrogen Traps in Stable Hydrogen Isotope-Ratio Mass Spectrometry

    E-print Network

    other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen to a VG Micromass model 602 dual inlet isotope-ratio mass spectrometer.3,4,6 Gaseous hydrogenCaution on the Use of Liquid Nitrogen Traps in Stable Hydrogen Isotope-Ratio Mass Spectrometry

  7. Stable Isotopes in Foraminiferal Carbonate Steve Cooke and Eelco J. Rohling

    E-print Network

    Rohling, Eelco

    .1.5. Advection 2.2. Oxygen isotope ratios in foraminiferal carbonate 2.2.1. Equilibrium fractionation 2.2.5.2. Inorganic carbon 3.3. Carbon isotope ratios in foraminiferal carbonate 3.3.1. Equilibrium fractionation 31 Stable Isotopes in Foraminiferal Carbonate Steve Cooke and Eelco J. Rohling School of Ocean

  8. Deuterium stable isotope ratios as tracers of water resource use: an experimental test with rock doves

    Microsoft Academic Search

    Andrew E. McKechnie; Blair O. Wolf; Carlos Martínez del Rio

    2004-01-01

    Naturally-occurring deuterium stable isotope ratios can potentially be used to trace water resource use by animals, but estimating the contribution of isotopically distinct water sources requires the accurate prediction of isotopic discrimination factors between water inputs and an animal’s body water pool. We examined the feasibility of using estimates of water fluxes between a bird and its environment with a

  9. A high precision pulsed quantum cascade laser spectrometer for measurements of stable isotopes of carbon dioxide

    E-print Network

    Saleska, Scott

    A high precision pulsed quantum cascade laser spectrometer for measurements of stable isotopes problem opens the possibility of field worthy rapid response isotopic instrumentation and attests to the maturity of these lasers as spectroscopic sources. 1. Introduction The measurement of isotopic ratios

  10. Stable Carbon Isotope Characterization of Non-Methane Hydrocarbons in Vancouver and Toronto Airsheds

    Microsoft Academic Search

    G. MacIsaac; M. J. Whiticar; J. Rudolph; S. Gao

    2004-01-01

    We have developed an approach using stable carbon isotopes as tool to understanding distribution and free radical chemistry of Volatile Organic Compounds (VOCs) in urban airsheds. Carbon isotope ratios are indirect tracers for the reactions of non-methane hydrocarbons (NMHC) with OH radicals. The carbon isotope signatures are diagnostic of the source inputs and trajectories and potentially fingerprint emissions. Compound Specific

  11. MIXING MODELS IN ANALYSES OF DIET USING MULTIPLE STABLE ISOTOPES: A CRITIQUE

    EPA Science Inventory

    Stable isotopes have become widely used in ecology to quantify the importance of different sources based on their isotopic signature. One example of this has been the determination of food webs, where the isotopic signatures of a predator and various prey items can be used to de...

  12. DNA BUOYANT DENSITY SHIFTS DURING 15N DNA STABLE ISOTOPE PROBING.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Successful use of 13C stable isotope probing (SIP) to investigate microbial function in natural environments has stimulated interest in SIP technology using other isotopes. 15N-SIP is effective in buoyant density (BD) gradient separation of isotopically-enriched DNA, however, the resulting change in...

  13. Modern tendencies in the enrichment of stable isotopes and their applications in the USSR and elsewhere

    NASA Astrophysics Data System (ADS)

    Tikhomirov, A.

    1992-08-01

    Emphasis is placed on the increased use of enriched stable isotopes resulting from the demands of fundamental physical research, medical diagnostic techniques, and the development of new materials. Newly developed methods of separation, such as the centrifugal method, are now in use side by side with the "traditional" electromagnetic method for producing isotopes of middle and heavy masses. We propose parameters for the estimation of changes in demand for stable isotopes, and point out the increased requirements on the isotopic purity of enriched isotopes. A state-of-the-art assessment of the electromagnetic separation method is given.

  14. Forensic applications of light-element stable isotope ratios of Ricinus communis seeds and ricin preparations.

    PubMed

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

    2013-01-01

    Seeds of the castor plant Ricinus communis are of forensic interest because they are the source of the poison ricin. We tested whether stable isotope ratios of castor seeds and ricin preparations can be used as a forensic signature. We collected over 300 castor seed samples worldwide and measured the C, N, O, and H isotope ratios of the whole seeds and oil. We prepared ricin by three different procedures, acetone extraction, salt precipitation, and affinity chromatography, and compared their isotope ratios to those of the source seeds. The N isotope ratios of the ricin samples and source seeds were virtually identical. Therefore, N isotope ratios can be used to correlate ricin prepared by any of these methods to source seeds. Further, stable isotope ratios distinguished >99% of crude and purified ricin protein samples in pairwise comparison tests. Stable isotope ratios therefore constitute a valuable forensic signature for ricin preparations. PMID:23130759

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

    Microsoft Academic Search

    Eric S. Long; Richard A. Sweitzer; Duane R. Diefenbach; Merav Ben-David

    2005-01-01

    Increased use of stable isotope analysis to examine food-web dynamics, migration, transfer of nutrients, and behavior will likely result in expansion of stable isotope studies investigating human-induced global changes. Recent elevation of atmospheric CO2 concentration, related primarily to fossil fuel combustion, has reduced atmospheric CO2 ?13C (13C\\/12C), and this change in isotopic baseline has, in turn, reduced plant and animal

  16. Documenting the diet in ancient human populations through stable isotope analysis of hair.

    PubMed Central

    Macko, S A; Engel, M H; Andrusevich, V; Lubec, G; O'Connell, T C; Hedges, R E

    1999-01-01

    Fundamental to the understanding of human history is the ability to make interpretations based on artefacts and other remains which are used to gather information about an ancient population. Sequestered in the organic matrices of these remains can be information, for example, concerning incidence of disease, genetic defects and diet. Stable isotopic compositions, especially those made on isolates of collagen from bones, have been used to help suggest principal dietary components. A significant problem in the use of collagen is its long-term stability, and the possibility of isotopic alteration during early diagenesis, or through contaminating condensation reactions. In this study, we suggest that a commonly overlooked material, human hair, may represent an ideal material to be used in addressing human diets of ancient civilizations. Through the analysis of the amino-acid composition of modern hair, as well as samples that were subjected to radiation (thus simulating ageing of the hair) and hair from humans that is up to 5200 years old, we have observed little in the way of chemical change. The principal amino acids observed in all of these samples are essentially identical in relative abundances and content. Dominating the compositions are serine, glutamic acid, threonine, glycine and leucine, respectively accounting for approximately 15%, 17%, 10%, 8% and 8% of the total hydrolysable amino acids. Even minor components (for example, alanine, valine, isoleucine) show similar constancy between the samples of different ages. This constancy clearly indicates minimal alteration of the amino-acid composition of the hair. Further, it would indicate that hair is well preserved and is amenable to isotopic analysis as a tool for distinguishing sources of nutrition. Based on this observation, we have isotopically characterized modern individuals for whom the diet has been documented. Both stable nitrogen and carbon isotope compositions were assessed, and together provide an indication of trophic status, and principal type (C3 or C4) of vegetation consumed. True vegans have nitrogen isotope compositions of about 7/1000 whereas humans consuming larger amounts of meat, eggs, or milk are more enriched in the heavy nitrogen isotope. We have also analysed large cross-sections of modern humans from North America and Europe to provide an indication of the variability seen in a population (the supermarket diet). There is a wide diversity in both carbon and nitrogen isotope values based at least partially on the levels of seafood, corn-fed beef and grains in the diets. Following analysis of the ancient hair, we have observed similar trends in certain ancient populations. For example, the Coptics of Egypt (1000 BP) and Chinchorro of Chile (5000-800 BP) have diets of similar diversity to those observed in the modern group but were isotopically influenced by local nutritional sources. In other ancient hair (Egyptian Late Middle Kingdom mummies, ca. 4000 BP), we have observed a much more uniform isotopic signature, indicating a more constant diet. We have also recognized a primary vegetarian component in the diet of the Neolithic Ice Man of the Oetztaler Alps (5200 BP). In certain cases, it appears that sulphur isotopes may help to further constrain dietary interpretations, owing to the good preservation and sulphur content of hair. It appears that analysis of the often-overlooked hair in archaeological sites may represent a significant new approach for understanding ancient human communities. PMID:10091248

  17. The Relative Abundances of Carbon and its Isotopes in Cataclysmic Variables

    NASA Astrophysics Data System (ADS)

    Harrison, Thomas E.; Osborne, Heather; Howell, Steve; Johnson, Joni

    2002-02-01

    We have an NSF-funded program to investigate the chemical and isotopic abundances of carbon in the photospheres of the secondary stars of cataclysmic variables. We propose to use OSIRIS on the CTIO 4 m to obtain medium resolution K-band spectra of a sample of ~ 15 cataclysmic variables (CVs). We will use these spectra to examine the chemical and isotopic abundances of carbon in the photospheres of their secondary stars. Models of close binary star evolution predict that both the abundance and isotopic ratio (^12C/^13C) decrease as the secondary star losses mass. Observations we have obtained using CRSP on the KPNO 2.1m confirm this scenario for a number of longer- period CV systems. We propose to observe a larger sample of CVs covering the entire observed range in orbital period to determine if the model predictions are correct. In addition, the chemical and isotopic abundances depend on the evolutionary history of the CV. Models by Marks & Sarna (1998) predict that if the CV accreted significant material from the common envelope phase, or from earlier classical novae eruptions, the chemical and isotopic abundances will be different from scenarios where this did not occur. To examine this, we will observe a few classical novae to investigate whether their secondary stars reveal evidence for this isotopic enrichment. Our program requires two nights with OSIRIS on the CTIO 4m in 2002A.

  18. Status of stable isotope enrichment, products, and services at the Oak Ridge National Laboratory

    SciTech Connect

    Aaron, W.S.; Tracy, J.G.; Collins, E.D.

    1996-10-01

    The Oak Ridge National Laboratory (ORNL) has been supplying enriched stable and radioactive isotopes to the research, medical, and industrial communities for over 50 years. Very significant changes have occurred in this effort over the past several years, and, while many of these changes have had a negative impact on the availability of enriched isotopes, more recent developments are actually improving the situation for both the users and the producers of enriched isotopes. ORNL is still a major producer and distributor of radioisotopes, but future isotope enrichment operations conducted at the Isotope Enrichment Facility (IEF) will be limited to stable isotopes. Among the positive changes in the enriched stable isotope area are a well-functioning, long-term contract program, which offers stability and pricing advantages; the resumption of calutron operations; the adoption of prorated conversion charges, which greatly improves the pricing of isotopes to small users; SIO 9002 registration of the IEF`s quality management system; and a much more customer-oriented business philosophy. Efforts are also being made to restore and improve upon the extensive chemical and physical form processing capabilities that once existed in the enriched stable isotope program. Innovative ideas are being pursued in both technical and administrative areas to encourage the beneficial use of enriched stable isotopes and the development of related technologies.

  19. Stable isotope ecohydrology of semiarid shrubland in northwestern Mexico

    NASA Astrophysics Data System (ADS)

    Yepez, E. A.; Tarin, T.; Garatuza-Payan, J.; Watts, C. J.; Rodriguez, J. C.; Vivoni, E.; Robles-Morua, A.

    2013-05-01

    Ecosystem fluxes in seasonally dry ecosystems are fundamentally driven by availability of water and further ecohydrolgical processes that are triggered during the wet-growing season. One of the initial steps towards defining the functional fate of precipitation in ecosystems (i.e. influence on productivity or decomposition) is to partition evapotranspiration (ET) into its component fluxes. Aided by a real time field monitoring scheme of stable isotopes of water vapor to produce Keeling plots and micromet-driven modeling of the isotopic composition of soil evaporation (E) and transpiration (T) of representative species of a subtropical shrubland, we aimed to partitioning ET at hourly time steps during the peak monsoon season. The study was conducted in the state of Sonora Mexico at a long term eddy covariance monitoring site part of MexFlux. The ecosystem is a legume-rich subtropical shrubland that gets 550 mm of rain yearly with 70% of the total occurring during the summer monsoon season. Preliminary results indicate that on a daily scale in this ecosystem T is the dominant component of ET (T/ET 0.8 to 1) during the early morning (7 to 10 hrs local time) but drops to 60 to 50 % during the warmest part of the day (11 to 15 hrs) when the vegetation down regulate stomatal conductance and solar radiation reaches more directly the soil. Later in the afternoon (16 to 18 hrs), T/ET generally bounces back to 0.8 to 0.9 levels. Although the actual T/ET fraction varies depending on the soil moisture content in shallow soil layers, this general pattern is maintained many days through the warm rainy season and has implications to attribute the influence of rain to ecosystem function.

  20. Verifying Southern Hemisphere trends in atmospheric carbon dioxide stable isotopes

    NASA Astrophysics Data System (ADS)

    Allison, C. E.; Francey, R. J.

    2007-11-01

    Stable isotopes of carbon dioxide distinguish between oceanic and terrestrial uptake of accumulating atmospheric carbon dioxide. At Cape Grim (41°S, 141°E), two Commonwealth Scientific and Industrial Research Organisation programs provide ?13C and ?18O of CO2 employing different collection, sample pretreatment, and calibration strategies that exemplify calibration problems. A comprehensive reexamination of methods results in ?13C agreement of 0.005 ± 0.004‰ through 14 overlapping years of data and suggests we have described and accounted for the main sources of bias. For ?18O, flask storage effects and early standard assignment problems contribute to larger variation and the comparable differences are 0.024 ± 0.184‰. Cape Grim records are reissued with uncertainties reflecting the histories of each method, as well as selected "best" records for ?13C from 1981, and for ?18O from 1978. The uncertainties reflect the internal consistency against an in-house reference, of most interest in determining the limits of temporal behavior, and can be combined with a larger fixed uncertainty if a Cape Grim record is used to quantify spatial differences from sites operated by different measurement laboratories. Marked variability on seasonal and interannual timescales is observed in both isotope records. The geographical location and sampling strategy at Cape Grim ensures large-scale (hemispheric) representativeness on interannual timescales, and we show differences from comparable records maintained by the University of Colorado (using National Oceanic and Atmospheric Administration flasks) and Scripps Institution of Oceanography. The long-term Southern Hemisphere relationships between ?13C and CO2 are explored for the seasonal and interannual variability in the Cape Grim record. The interannual relationship is characterized by distinct periods of ?13C leveling immediately following increased global CO2 growth rate.

  1. Tracking variations of catchment storage with stable water isotopes

    NASA Astrophysics Data System (ADS)

    Heidbuechel, I.; Troch, P. A.

    2012-04-01

    The hydrologic response function (HRF) describes how fast a catchment responds to a precipitation event. The transit time distribution (TTD) determines how long water from an event spends in a catchment. We know that the HRF and the TTD are different from each other if catchment storage varies in time. We can use this knowledge, reverse the logic and track storage in a catchment by determining how the HRF and the TTD vary over a period of time. The HRF can be determined by comparing water fluxes into and out of the catchment. The TTD is most easily measured by using stable water isotopes as tracers and keeping track of them in both inflow and outflow. The difference in the shape of the two functions informs us whether water is being released from storage or whether water is added to storage. If a catchment reacts very fast to a precipitation event (short HRF) but the TTD of the event is skewed towards longer transit times, it means that a large fraction of the outflowing water will be released from storage (pre-event water). If a catchment reacts more slowly, then the shapes of the HRF and the TTD are more similar and a higher fraction of outflow will be event water. We used isotope and water flux data from a small mountainous semi-arid catchment with high variability in total catchment storage to demonstrate that the method yields reasonable results. We also ran an infiltration model (HYDRUS) to test our hypothesis for different scenarios (antecedent moisture conditions and precipitation event properties).

  2. Stable nitrogen isotopes of nestling tree swallows indicate exposure to different types of oil sands reclamation.

    PubMed

    Farwell, A J; Harms, N J; Smits, J E G; Dixon, D G

    2014-01-01

    Tree swallows (Tachycineta bicolor) inhabiting reclaimed wetlands on the oil sands in northern Alberta are potentially exposed to elevated levels of oil sands constituents such as polycyclic aromatic compounds (PAC) through diet. While increased detoxification enzyme activity as measured using 7-ethoxyresorufin O-deethylase in nestlings is a generally accepted indicator of exposure to oil sands constituents, there is no apparent method to detect dietary exposure specific to oil sands processed material (OSPM). In this study, stable C and N isotopes were analyzed from muscle and feathers of nestling tree swallows (15 d old) to distinguish dietary exposure of birds near reference and OSPM wetlands. High ?¹?N and low ?¹³C values in the nestling tissues differentiated those from the OSPM wetlands and reference sites. Lower ?¹?N values of nestlings compared to the ?¹?N values of larval chironomids from an earlier study suggested that the majority of the diet of the nestlings was derived from non-OSPM sources, despite residence near and on the OSPM wetlands. Our finding of limited utilization of OSPM resources by tree swallows indicates either low abundance or diversity of dietary items emerging from OSPM wetlands, or sensory avoidance of prey from those wetlands. Minimal consumption of OSPM-derived dietary sources may be attributed to published findings of limited adverse effects on tree swallow reproduction, or growth and development for these same nestlings. This study demonstrated that stable isotope analysis, particularly for N isotopes, may serve as a useful tool to trace dietary exposure to OSPM constituents as part of avian ecotoxicology assessments of reclaimed wetlands on the oil sands. PMID:24627996

  3. Nitrate stable isotopes: Tools for determining nitrate sources among different land uses in the Mississippi River Basin

    USGS Publications Warehouse

    Chang, Cecily C.Y.; Kendall, C.; Silva, S.R.; Battaglin, W.A.; Campbell, D.H.

    2002-01-01

    A study was conducted to determine whether NO3- stable isotopes (??15N and ??18O), at natural abundance levels, could discriminate among NO3- sources from sites with different land uses at the basin scale. Water samples were collected from 24 sites in the Mississippi River Basin from five land-use categories: (1) large river basins (>34 590 km2) draining multiple land uses and smaller basins in which the predominant land use was (2) urban (3) undeveloped, (4) crops, or (5) crops and livestock. Our data suggest that riverine nitrates from different land uses have overlapping but moderately distinct isotopic signatures. ??18O data were critical in showing abrupt changes in NO3- source with discharge. The isotopic values of large rivers resembled crop sites, sites with livestock tended to have ??15N values characteristic of manure, and urban sites tended to have high ??18O values characteristic of atmospheric nitrate.

  4. Temporal variability of nitrogen stable isotopes in primary uptake compartments in four streams differing in human impacts.

    PubMed

    Pastor, Ada; Riera, Joan Lluís; Peipoch, Marc; Cañas, Lídia; Ribot, Miquel; Gacia, Esperança; Martí, Eugènia; Sabater, Francesc

    2014-06-17

    Understanding the variability of the natural abundance in nitrogen stable isotopes (expressed as ?(15)N) of primary uptake compartments (PUCs; e.g., epilithon or macrophytes) is important due to the multiple applications of stable isotopes in freshwater research and can give insights into environmental and anthropogenic factors controlling N dynamics in streams. While previous research has shown how ?(15)N of PUCs varies with ?(15)N of dissolved inorganic N (DIN) among streams, less is known about how ?(15)N of PUCs varies over time. Here, we examined monthly variation of ?(15)N of PUCs and of DIN species (nitrate and ammonium) over a year, and compared it among streams with contrasting human impacts and PUC types. Our results showed no evidence of isotopic seasonal patterns. Temporal variability in ?(15)N-PUCs increased with human impact, being the highest in the urban stream, probably influenced by the high variability of ?(15)N-DIN. Among compartments, in-stream PUCs characterized by fast turnover rates, such as filamentous algae, showed the highest temporal variability in ?(15)N values (from -3.6 to 23.2 ‰). Our study elucidates some of the environmental and biological controls of temporal variability of ?(15)N in streams, which should be taken into account when using stable isotopes as an ecological tool. PMID:24837817

  5. Stable isotope-based diet reconstructions of Turkana Basin hominins

    PubMed Central

    Cerling, Thure E.; Manthi, Fredrick Kyalo; Mbua, Emma N.; Leakey, Louise N.; Leakey, Meave G.; Leakey, Richard E.; Brown, Francis H.; Grine, Frederick E.; Hart, John A.; Kaleme, Prince; Roche, Hélène; Uno, Kevin T.; Wood, Bernard A.

    2013-01-01

    Hominin fossil evidence in the Turkana Basin in Kenya from ca. 4.1 to 1.4 Ma samples two archaic early hominin genera and records some of the early evolutionary history of Paranthropus and Homo. Stable carbon isotopes in fossil tooth enamel are used to estimate the fraction of diet derived from C3 or C4 resources in these hominin taxa. The earliest hominin species in the Turkana Basin, Australopithecus anamensis, derived nearly all of its diet from C3 resources. Subsequently, by ca. 3.3 Ma, the later Kenyanthropus platyops had a very wide dietary range—from virtually a purely C3 resource-based diet to one dominated by C4 resources. By ca. 2 Ma, hominins in the Turkana Basin had split into two distinct groups: specimens attributable to the genus Homo provide evidence for a diet with a ca. 65/35 ratio of C3- to C4-based resources, whereas P. boisei had a higher fraction of C4-based diet (ca. 25/75 ratio). Homo sp. increased the fraction of C4-based resources in the diet through ca. 1.5 Ma, whereas P. boisei maintained its high dependency on C4-derived resources. PMID:23733966

  6. Development of a stable isotope dilution assay for tenuazonic acid.

    PubMed

    Asam, Stefan; Liu, Yang; Konitzer, Katharina; Rychlik, Michael

    2011-04-13

    A stable isotope dilution assay (SIDA) for the Alternaria mycotoxin tenuazonic acid was developed. Therefore, [(13)C(6),(15)N]-tenuazonic acid was synthesized from [(13)C(6),(15)N]-isoleucine by Dieckmann intramolecular cyclization after acetoacetylation with diketene. The synthesized [(13)C(6),(15)N]-tenuazonic acid was used as the internal standard for determination of tenuazonic acid in tomato products by liquid chromatography tandem mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine. Method validation revealed a limit of detection of 0.1 ?g/kg and a limit of quantitation of 0.3 ?g/kg. Recovery was close to 100% in the range of 3-300 ?g/kg. Determination of tenuazonic acid in two samples of different tomato ketchups (naturally contaminated) was achieved with a coefficient of variation of 2.3% and 4.7%. Different tomato products (n = 16) were analyzed for their content of tenuazonic acid using the developed SIDA. Values were between 15 and 195 ?g/kg (tomato ketchup, n = 9), 363 and 909 ?g/kg (tomato paste, n = 2), and 8 and 247 ?g/kg (pureed tomatoes and comparable products, n = 5). PMID:21370870

  7. Stable isotope studies of nicotine kinetics and bioavailability

    SciTech Connect

    Benowitz, N.L.; Jacob, P. 3d.; Denaro, C.; Jenkins, R. (Univ. of California, San Francisco (USA))

    1991-03-01

    The stable isotope-labeled compound 3',3'-dideuteronicotine was used to investigate the disposition kinetics of nicotine in smokers, the systemic absorption of nicotine from cigarette smoke, and the bioavailability of nicotine ingested as oral capsules. Blood levels of labeled nicotine could be measured for 9 hours after a 30-minute intravenous infusion. Analysis of disposition kinetics in 10 healthy men revealed a multiexponential decline after the end of an infusion, with an elimination half-life averaging 203 minutes. This half-life was longer than that previously reported, indicating the presence of a shallow elimination phase. Plasma clearance averaged 14.6 ml/min/kg. The average intake of nicotine per cigarette was 2.29 mg. A cigarette smoke-monitoring system that directly measured particulate matter in smoke was evaluated in these subjects. Total particulate matter, number of puffs on the cigarette, total puff volume, and time of puffing correlated with the intake of nicotine from smoking. The oral bioavailability of nicotine averaged 44%. This bioavailability is higher than expected based on the systemic clearance of nicotine and suggests that there may be significant extrahepatic metabolism of nicotine.

  8. A stable carbon isotope and biological marker study of Polish bituminous coals and carbonaceous shales

    USGS Publications Warehouse

    Kotarba, M.J.; Clayton, J.L.

    2003-01-01

    Biological marker and carbon isotopic compositions of coals and carbonaceous shales from the Upper Carboniferous strata of the Upper Silesian (USCB), Lower Silesian (LSCB), and Lublin (LCB) coal basins were determined to assess depositional conditions and sources of the organic matter. n-Alkane, sterane, and isoprenoid distribution, and carbon isotope ratios are consistent with an origin from higher plants. In some cases, pristane/phytane (Pr/Ph) ratios of carbonaceous shales (roof and floor shales) are < 1.0, while the associated coals have high ratios (??? 1.0). This suggests that reducing conditions prevailed during deposition of the shales, but a period of oxidizing conditions accompanied deposition of the coals. Steranes present in coal extracts are dominated by the 14??(H)17??(H)20R C29 stereoisomers, typical, but not conclusive, of higher plant origin. Carbonaceous shales exhibit a wider range of sterane composition, suggesting local, significant input of algal organic matter. Significant amounts of benzohopanes and gammacerane are present in some coals. Although benzohopanes are present at least in small amounts in samples from many different environments, they have been reported to occur most commonly in marine environments. The present study seems to provide the first example where benzohopanes have been reported in significant amounts in terrestrial organic matter. Gammacerane is abundant in rocks or sediments deposited in carbonate or highly saline marine environments. The finding of high gammacerane concentrations in the coals expands the depositional settings in which it has been observed and questions its utility as an independent indicator of hypersaline carbonate environments. Stable carbon isotope composition of coals, and type III kerogen in carbonaceous shales as well as correlation of stable carbon isotope composition of saturated and aromatic hydrocarbons in carbonaceous shales from both the USCB and the LSCB indicate terrigenous origin. Bitumens are always co-genetic with associated coals and kerogens. Isotopic data reveal that Sofer's genetic classification of oils is not applicable to organic matter in coals. ?? 2003 Elsevier B.V. All rights reserved.

  9. Results from the stable isotope sampling network in Carboeuroflux

    NASA Astrophysics Data System (ADS)

    Yakir, D.; Hemming, D.

    2002-12-01

    Integrating stable isotopic measurements of canopy air and ecosystem organics with flux tower and ecophysiological data provides a powerful tool to differentiate between carbon sources and sinks, and scale-up processes from plant to ecosystem levels. During the 2001 and 2002 growing-seasons monthly flask samples of nocturnal canopy air and ecosystem organics were collected from selected forest flux sites within the Carboeuroflux network (13 sites in 2001 and 18 in 2002). Flask air was analysed for CO2 concentration ([CO2]), and the carbon and oxygen isotopic compositions (?13C and ?18O) of this CO2. The ?18O of waters distilled from leaf, stem and soil samples, and the ?13C and ?18O of these dried, homogonised organic samples were also measured. Analytical precisions were ñ0.1ppmv for [CO2], ñ0.1 permil and ñ0.2 permil for the ?13C and ?18O of atmospheric CO2, ñ0.05 permil for water ?18O and ñ0.1 permil for both the ?13C and ?18O of organics. The ?13C of ecosystem respired CO2 (?13CR) was determined for each sampling period and location using a Keeling plot approach. Ecosystem discrimination (?13CE) was estimated as the difference between the ?13Cs of background atmospheric CO2 and ecosystem respired CO2. The seasonal and spatial variation in these variables, and the ?13C and ?18O compositions of the organic samples are examined relative to meteorological and ecophysiological conditions. We assessed the potential for using the ?18O of ecosystem respired CO2 (?18OR) together with that of soil and leaf waters to partition between the soil and above-ground respired CO2 sources. At sites where soil ?13C varied significantly from leaf ?13C, we also assessed the partitioning potential in using the ?13C data. More intensive sampling campaigns, including incubations in branch-bags, and leaf, trunk and soil chambers, were also conducted at specific sites to examine the partitioning and scale relationships between individual source CO2 contributions and ?13CR. These experiments are still being conducted and their final results will be presented. Significant variations are observed in ?13CE and ?13CR spatially, seasonally and between years. The observed variations in ?13CE and ?13CR follow a general trend with daytime average temperature, such that the most enriched compositions are typically observed during the mid-season and in warmer, more continental climatic locations. The average seasonal range in ?13CR at individual sites is ~5 permil, between ~-26 permil and -21 permil, although, the average range between sites is also ~5 permil. The average ?18O compositions of soil and twig waters for both years were -6.6 permil and -6.0 permil respectively (SD=2.5 permil). Throughout each season and between sites these compositions varied from 0 permil to -10 permil. The results of this network highlight some of the applications of stable isotope monitoring for assessing local and regional-scale terrestrial ecosystem dynamics. In particular, the observed regional variations in ?13CE may have implications for modelling regional carbon sources and/or sinks from measurements of the ?13C of atmospheric CO2, as these estimates currently assume constant ?13CE.

  10. A guide for the laboratory information management system (LIMS) for light stable isotopes--Versions 7 and 8

    USGS Publications Warehouse

    Coplen, Tyler B.

    2000-01-01

    The reliability and accuracy of isotopic data can be improved by utilizing database software to (i) store information about samples, (ii) store the results of mass spectrometric isotope-ratio analyses of samples, (iii) calculate analytical results using standardized algorithms stored in a database, (iv) normalize stable isotopic data to international scales using isotopic reference materials, and (v) generate multi-sheet paper templates for convenient sample loading of automated mass-spectrometer sample preparation manifolds. Such a database program, the Laboratory Information Management System (LIMS) for Light Stable Isotopes, is presented herein. Major benefits of this system include (i) a dramatic improvement in quality assurance, (ii) an increase in laboratory efficiency, (iii) a reduction in workload due to the elimination or reduction of retyping of data by laboratory personnel, and (iv) a decrease in errors in data reported to sample submitters. Such a database provides a complete record of when and how often laboratory reference materials have been analyzed and provides a record of what correction factors have been used through time. It provides an audit trail for laboratories. LIMS for Light Stable Isotopes is available for both Microsoft Office 97 Professional and Microsoft Office 2000 Professional as versions 7 and 8, respectively. Both source code (mdb file) and precompiled executable files (mde) are available. Numerous improvements have been made for continuous flow isotopic analysis in this version (specifically 7.13 for Microsoft Access 97 and 8.13 for Microsoft Access 2000). It is much easier to import isotopic results from Finnigan ISODAT worksheets, even worksheets on which corrections for amount of sample (linearity corrections) have been added. The capability to determine blank corrections using isotope mass balance from analyses of elemental analyzer samples has been added. It is now possible to calculate and apply drift corrections to isotopic data based on the time of day of analysis. Whereas Finnigan ISODAT software is confined to using only a single peak for calculating delta values, LIMS now enables one to use the mean of two or more reference injections during a continuous flow analysis to calculate delta values. This is useful with Finnigan?s GasBench II online sample preparation system. Concentrations of carbon, nitrogen, and sulfur can be calculated based one or more isotopic reference materials analyzed with a group of samples. Both sample data and isotopic analysis data can now be exported to Excel files. A calculator for determining the amount of sample needed for isotopic analysis based on a previous amount of sample and continuous flow area is now an integral part of LIMS for Light Stable Isotopes. LIMS for Light Stable Isotopes can now assign an error code to Finnigan elemental analyzer analyses in which one of the electrometers has saturated due to analysis of too much sample material, giving rise to incorrect isotopic abundances. Information on downloading this report and downloading code and databases is provided at the Internet addresses: http://water.usgs.gov/software/geochemical.html or http://www.geogr.uni-jena.de/software/geochemical.html in the Eastern Hemisphere.

  11. A 15N stable isotope semen label to detect mating in the malaria mosquito Anopheles arabiensis Patton

    Microsoft Academic Search

    Michelle EH Helinski; Rebecca C Hood; Doris Gludovacz; Leo Mayr; Bart GJ Knols

    2008-01-01

    In previous studies it was determined that the stable isotope 13-carbon can be used as a semen label to detect mating events in the malaria mosquito Anopheles arabiensis. In this paper we describe the use of an additional stable isotope, 15-nitrogen (15N), for that same purpose. Both stable isotopes can be analysed simultaneously in a mass spectrometer, offering the possibility

  12. Effects of Water Vapor on the Data Quality of the Stable Oxygen Isotopic Ratio of Atmospheric Carbon Dioxide

    Microsoft Academic Search

    C. U. Evans; J. W. White; B. Vaughn; P. P. Tans; L. Pardo

    2007-01-01

    The stable oxygen isotopic ratio of carbon dioxide can potentially track fundamental indicators of environmental change such as the balance between photosynthesis and respiration on regional to global scales. The Stable Isotope Laboratory (SIL) at the Institute of Arctic and Alpine Research (INSTAAR), University of Colorado at Boulder, has measured the stable isotopes of atmospheric carbon dioxide from more than

  13. Water Stable Isotopes: Atmospheric Composition and Applications in Polar Ice Core Studies

    NASA Astrophysics Data System (ADS)

    Jouzel, J.

    2003-12-01

    Natural waters formed of ˜99.7% of H216O are also constituted of other stable isotopic molecules, mainly H218O (˜2‰), H217O (˜0.5‰), and HD16O (˜0.3‰), where H and D (deuterium) correspond to 1H and 2H, respectively. Owing to slight differences in physical properties of these molecules, essentially their saturation vapor pressure, and their molecular diffusivity in air, fractionation processes occur at each phase change of the water except sublimation and melting of compact ice. As a result, the distribution of these water isotopes varies both spatially and temporally in the atmosphere, in the precipitation, and, in turn, in the various reservoirs of the hydrosphere and of the cryosphere. These isotopic variations have applications in such fields as climatology and cloud physics. More importantly, they are at the origin of two now well-established disciplines: isotope hydrology and isotope paleoclimatology. The various aspects dealing with isotope hydrology are reviewed by Kendall (see Chapter 5.11). In this chapter, we focus on this field known as "isotope paleoclimatology." As the behavior of H217O in the atmospheric water is very similar to that of H218O (more abundant and easier to precisely determine), isotope paleoclimatology is only based on the changes in concentrations of HDO and H218O. These concentrations are given with respect to a standard as ?=(Rsample-RSMOW)/RSMOW and expressed in per mil ? units (?D and ?18O, respectively). In this definition, Rsample and RSMOW are the isotopic ratios of the sample and of the Vienna Standard Mean Ocean Water (V-SMOW) with D/H and 18O/16O atomic ratios of 155.76×10-6 and 2005.2×10-6, respectively (Hageman et al., 1970; Baerstchi, 1976; Gonfiantini, 1978).The use of water stable isotopes in paleoclimatology is based on the fact that their present-day distribution in precipitation is strongly related to climatological parameters. Of primary interest is the linear relationship between annual values of ?D and ?18O and mean annual temperature at the precipitation site, Ts, that is observed at middle and high latitudes (Figure 1). This relationship, which, as discussed in Section 4.08.3, is well explained by both simple and complex isotopic models, has given rise to the notion of "isotopic paleothermometer." In a conventional approach, the present-day spatial relationship between the isotopic concentration of the precipitation ?p (where ?p stands either for ?D or for ?18O of the precipitation, which can indifferently be used as paleothermometers) and Ts, defined over a certain region, is assumed to hold in time throughout this region. In this approach, it is assumed that the temporal slope, which applies to the isotope-temperature relationship through different climates over time at a single geographic location and should be used to interpret isotopic variations, observed at this site in terms of temperature changes, and the spatial slope (Sspat=d?p/dTs) are similar. A so-called "modern analogue method" is thus used, similar to that adopted in most other methods for reconstructing paleoclimates. Of course, the fact that present-day isotope concentrations and local temperatures are correlated is not sufficient to validate this critical assumption. Such factors as the evaporative origin and the seasonality of precipitation can also affect ?D and ?18O. If these factors change markedly under different climates, the spatial slope can no longer be taken as a reliable surrogate of the temporal slope for interpreting the isotopic signal. For example, there is now ample evidence that temporal slopes are considerably lower (by up to a factor of 2) than the observed present-day spatial slope, for Greenland sites. (13K)Figure 1. Annual ?18O in precipitation versus annual surface temperature for: (a) 3 yr run and (b) observations as simulated by the NASA/GISS isotopic GCM (after Jouzel et al., 1987a). Present-day ?p distributions are characterized by two other interesting large-scale properties. First, there is no clear relationship be

  14. The plasma centrifuge: A compact, low cost, stable isotope separator. Phase 2 final technical report, September 15, 1991--September 14, 1995

    SciTech Connect

    Guss, W.

    1996-09-05

    Enriched stable isotopes are required for production of radionuclides as well as for research and diagnostic uses. Science Research Laboratory (SRL) has developed a plasma centrifuge for moderate throughput of enriched stable isotopes, such as {sup 13}C, {sup 17}O, {sup 18}O, and {sup 203}Tl, for medical as well as other applications. Dwindling isotope stocks have restricted the use of enriched isotopes and their associated labeled organic molecules in medical imaging to very few research facilities because of high costs of isotope separation. With the introduction of the plasma centrifuge separator, the cost per separated gram of even rarely occurring isotopes ({le} 1% natural abundance) is potentially many times lower than with other separation technologies (cryogenic distillation and calutrons). The centrifuge is a simple, robust, pulsed electrical discharge device that has successfully demonstrated isotope separation of small (mg) quantities of {sup 26}Mg. Based on the results of the Phase 2 program, modest enhancements to the power supplies and cooling systems, a centrifuge separator will have high repetition rate (60 pps) and high duty cycle (60%) to produce in one month kilogram quantities of highly enriched stable isotopes. The centrifuge may be used in stand-alone operation or could be used as a high-throughput pre-separation stage with calutrons providing the final separation.

  15. Trophic ecology of mullets during their spring migration in a European saltmarsh: A stable isotope study

    NASA Astrophysics Data System (ADS)

    Lebreton, Benoit; Richard, Pierre; Parlier, Emmanuel P.; Guillou, Gaël; Blanchard, Gérard F.

    2011-03-01

    Mullet populations are abundant in littoral waters throughout the world and play a significant role in organic matter fluxes. Mullets are opportunistic feeders: adults have frequently been shown to feed on primary producers (e.g. fresh or detrital plant material, microphytobenthos) but they may also feed on meiofauna. The population structure and stomach contents of mullets that colonize saltmarsh creeks in Aiguillon Bay (French Atlantic coast) were studied to determine if they use saltmarshes as a feeding ground in spring. Stable isotope analyses were carried out on mullets sampled to assess their diet during their spring migration. The mullet population was primarily composed of young-of-the-year (G0), 1 year-old (G1) of both Liza ramada and Liza aurata species and 3 year-old or older (G3+) L. ramada individuals. G0 and G3+ population densities increased during the spring period: catch per unit effort (CPUE) increased from 0.22 to 1.49 ind min -1 for the G0 age group; but stomach content analyses revealed that only G1 and G3+ feed in the saltmarsh. Isotopic signatures of G1 (spring: ? 13C: -14.8‰, ? 15N: 14.1‰) and G3+ mullets (spring: ? 13C: -16.9‰, ? 15N: 13.8‰) indicate that mullet growth is supported largely by primary consumers, such as benthic meiofauna or small macrofauna. Mullets are thus positioned at a much higher trophic level than true primary consumers.

  16. Breath carbon stable isotope ratios identify changes in energy balance and substrate utilization in humans.

    PubMed

    Whigham, L D; Butz, D E; Johnson, L K; Schoeller, D A; Abbott, D H; Porter, W P; Cook, M E

    2014-09-01

    Rapid detection of shifts in substrate utilization and energy balance would provide a compelling biofeedback tool for individuals attempting weight loss. As a proof of concept, we tested whether the natural abundance of exhaled carbon stable isotope ratios (breath ?(13)C) reflects shifts between negative and positive energy balance. Volunteers (n=5) consumed a 40% energy-restricted diet for 6 days followed by 50% excess on day 7. Breath was sampled immediately before and 1?h and 2?h after breakfast, lunch and dinner. Exhaled breath ?(13)C values were measured by cavity ring-down spectroscopy. Using repeated measures analysis of variance (ANOVA) followed by Dunnett's contrasts, pre-breakfast breath values on days 2-6 were compared with day 1, and postprandial day 7 time points were compared with pre-breakfast day 7. Energy restriction diminished pre-breakfast breath ?(13)C by day 3 (P<0.05). On day 7, increased energy intake was first detected immediately before dinner (-23.8±0.6 vs -21.9±0.7‰, P=0.002 (means±s.d.)), and breath ?(13)C remained elevated at least 2?h post dinner. In conclusion, when shifting between negative and positive energy balance, breath ?(13)C showed anticipated isotopic changes. Although additional research is needed to determine specificity and repeatability, this method may provide a biomarker for marked increases in caloric intake. PMID:24441037

  17. Recent Advances in Stable Isotope Techniques for N2O Source Partitioning in Soils

    NASA Astrophysics Data System (ADS)

    Baggs, E.; Mair, L.; Mahmood, S.

    2007-12-01

    The use of 13C, 15N and 18O enables us to overcome uncertainties associated with soil C and N processes and to assess the links between species diversity and ecosystem function. Recent advances in stable isotope techniques enable determination of process rates, and are fundamental for examining interactions between C and N cycles. Here we will introduce the 15N-, 18O- and 13C-enrichment techniques we have developed to distinguish between different N2O-producing processes in situ in soils, presenting selected results, and will critically assess their potential, alone and in combination with molecular techniques, to help address key research questions for soil biogeochemistry and microbial ecology. We have developed 15N- 18O-enrichment techniques to distinguish between, and to quantify, N2O production during ammonia oxidation, nitrifier denitrification and denitrification. This provides a great advantage over natural abundance approaches as it enables quantification of N2O from each microbial source, which can be coupled with quantification of N2 production, and used to examine interactions between different processes and cycles. These approaches have also provided new insights into the N cycle and how it interacts with the C cycle. For example, we now know that ammonia oxidising bacteria significantly contribute to N2O emissions from soils, both via the traditionally accepted ammonia oxidation pathway, and also via denitrification (nitrifier denitrification) which can proceed even under aerobic conditions. We are also linking emissions from each source to diversity and activity of relevant microbial functional groups, for example through the development and application of a specific nirK primer for the nitrite reductase in ammonia oxidising bacteria. Recently, isotopomers have been proposed as an alternative for source partitioning N2O at natural abundance levels, and offers the potential to investigate N2O production from nitrate ammonification, and overcomes the need to apply 18O-H2O to determine nitrifier denitrification. However, this only provides an estimated, not a quantified, contribution, and further developments are required for quantification using isotope enrichment. Despite some limitations, such techniques become even more powerful when linked with other recent developments, such as nanoSIMS, gene expression and 13C-stable isotope probing of microbial RNA, and when linked to other disciplines. These may help address remaining questions such as: which microbes are producing N2O in soil, what is the influence of plants and mycorrhizal fungi on rhizosphere processes, and where is denitrification occurring in soil?

  18. Relationships between the stable isotopic signatures of living and fossil foraminifera in Monterey Bay, California

    Microsoft Academic Search

    Jonathan B. Martin; Shelley A. Day; Anthony E. Rathburn; M. Elena Perez; Chris Mahn; Joris Gieskes

    2004-01-01

    Fossil foraminifera are critical to paleoceanographic reconstructions including estimates of past episodes of methane venting. These reconstructions rely on benthic foraminifera incorporating and retaining unaltered the ambient isotopic compositions of pore fluids and bottom waters. Comparisons are made here of isotopic compositions of abundant live and fossil foraminifera (Uvigerina peregrina, Epistominella pacifica, Bulimina mexicana, and Globobulimina pacifica) collected in Monterey

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Carbon and Sulfur Stable Isotope Records of the Early Paleogene

    NASA Astrophysics Data System (ADS)

    Dickens, G.; Backman, J.

    2012-12-01

    Secular records of stable carbon isotopes and stable sulfur isotopes from marine sediment provide primary tools for understanding past changes in global biogeochemical cycling. Over the Cenozoic, the most pronounced changes in ?13C and ?34S records happened during the late Paleocene and Early Eocene. The cause of these variations remains the source of debate, in part because the ?13C and ?34S records are not linked very well in the time domain. The early Cenozoic ?34S record principally comes from analyses of barite extracted from DSDP Sites 366 and 577 (Paytan et al., Science, 1996). However, Site 366 has no ?13C record and poorly preserved microfossil assemblages, and Site 577 has a problematic stratigraphy because of misplaced datums, and unrecognized core gaps and core overlaps. Here we generate a ?13C record at Site 366, realign the stratigraphy at Site 577, and place both records on a current time scale for the early Paleogene (Option 1; Westerhold et al., P3, 2008). There is now very little play in the relative and absolute timing of ?13C and ?34S changes across the early Paleogene. Between about 62 and 58 Ma, the ?13C of carbonate increased while the ? 34S of barite decreased. A marked change occurred at about 58 Ma: form this time to about 52 Ma, the ?13C of carbonate decreased but the ? 34S of barite continued to decrease. At about 52 Ma and a few million years after, both ?13C and ? 34S increased. Thus, the records are coupled but in a complex manner, and the series of hyperthermals happened when both ?13C and ? 34S decreased together. No model to date explains these basic observations satisfactorily. For example, volcanism as a cause for the ?34C drop does not explain the initial 4 Myr rise in ?13C and apparent coeval removal of carbon from the ocean and atmosphere; storage and release of terrestrial organic carbon as a cause for the rise and fall in ?13C does not explain the drop or subsequent rise in ?34S. Clearly, however, the idea that methane build-up in marine sediment during the late Paleocene and its subsequent discharge over the early Eocene is wrong, at least as presented (Dickens, Clim. Past, 2011). This is because such storage and release must drive significant anaerobic oxidation of methane (AOM) and the formation of Fe sulfides, which if depleted in 34S relative to seawater, would cause a positive ?34S excursion. Indeed, seafloor methane cannot be a significant player in global biogeochemical cycling during the early Paleogene, unless one invokes an unconventional notion: AOM leads to burial of 34S-enriched Fe sulfides.

  1. Calcium Isotopic Ratios and Rare Earth Element Abundances in Refractory Inclusions from Allende CV3 Chondrite

    Microsoft Academic Search

    Shichun Huang; Juraj Farkaš; Gang Yu; Michail I. Petaev; Stein B. Jacobsen

    Refractory inclusions in primitive meteorites are the oldest objects formed in the Solar System. They exhibit large mass-dependent isotopic effects in many elements, including Si, Mg and Ca, indicative of their complex origin. We report data for both mass-dependent (?) and mass-independent (?) Ca isotopic effects, and rare earth element (REE) abundances in six refractory inclusions from the Allende CV3

  2. Retrograde fluids in granulites: Stable isotope evidence of fluid migration

    SciTech Connect

    Morrison, J. (Univ. of Southern California, Los Angeles (United States)); Valley, J.W. (Univ. of Wisconsin, Madison (United States))

    1991-07-01

    Widespread retrograde alteration assemblages document the migration of mixed H{sub 2}O-CO{sub 2} fluids into granulite facies rocks in the Adirondack Mountains. Fluid migration is manifest by (1) veins and patchy intergrowths of chlorite {plus minus} sericite {plus minus} calcite, (2) small veins of calcite, many only identifiable by cathodoluminescence, and (3) high-density, CO{sub 2}-rich or mixed H{sub 2}O-CO{sub 2} fluid inclusions. The distinct and varied textural occurrences of the alteration minerals indicate that fluid-rock ratios were low and variable on a local scale. Stable isotope ratios of C, O, and S have been determined in retrograde minerals from samples of the Marcy anorthosite massif and adjacent granitic gneisses (charnockites). Retrograde calcite in the anorthosite has a relatively small range in both {delta}{sup 18}O{sub SMOW} and {delta}{sup 13}C{sub PDB} (8.6 to 14.9% and {minus}4.1 to 0.4%, respectively), probably indicating that the hydrothermal fluids that precipitated the calcite had exchanged with a variety of crustal lithologies including marbles and orthogneisses, and that calcite was precipitated over a relatively narrow temperature interval. Values of {delta}{sup 34}S{sub CDT} that range from 2.8 to 8.3% within the anorthosite can also be interpreted to reflect exchange between orthogneisses and metasediments. The recognition of retrograde fluid migration is particularly significant in granulite facies terranes because the controversy surrounding the origin of granulites arises in part from differing interpretations of fluid inclusion data, specifically, the timing of entrapment of high-density, CO{sub 2}-rich inclusions. Results indicate that retrograde fluid migration, which in some samples may leave only cryptic petrographic evidence, is a process capable of producing high-density, CO{sub 2}-rich fluid inclusions.

  3. Soil phosphate stable oxygen isotopes across rainfall and bedrock gradients.

    PubMed

    Angert, Alon; Weiner, Tal; Mazeh, Shunit; Sternberg, Marcelo

    2012-02-21

    The stable oxygen isotope compositions of soil phosphate (?(18)O(p)) were suggested recently to be a tracer of phosphorus cycling in soils and plants. Here we present a survey of bioavailable (resin-extractable or resin-P) inorganic phosphate ?(18)O(p) across natural and experimental rainfall gradients, and across soil formed on sedimentary and igneous bedrock. In addition, we analyzed the soil HCl-extractable inorganic ?(18)O(p), which mainly represents calcium-bound inorganic phosphate. The resin-P values were in the range 14.5-21.2‰. A similar range, 15.6-21.3‰, was found for the HCl-extractable inorganic ?(18)O(p), with the exception of samples from a soil of igneous origin that show lower values, 8.2-10.9‰, which indicate that a large fraction of the inorganic phosphate in this soil is still in the form of a primary mineral. The available-P ?(18)O(p) values are considerably higher than the values we calculated for extracellular hydrolysis of organic phosphate, based on the known fractionation from lab experiments. However, these values are close to the values expected for enzymatic-mediated phosphate equilibration with soil-water. The possible processes that can explain this observation are (1) extracellular equilibration of the inorganic phosphate in the soil; (2) fractionations in the soil are different than the ones measured at the lab; (3) effect of fractionation during uptake; and (4) a flux of intercellular-equilibrated inorganic phosphate from the soil microbiota, which is considerably larger than the flux of hydrolyzed organic-P. PMID:22243529

  4. Stable Isotopes in Ecological Sceinces: Bird and Fish Diet and Migration in Virginia

    NASA Astrophysics Data System (ADS)

    Schmidt, S.; Dias, R. F.; Ake, R.; Jones, C. M.

    2002-12-01

    The preservation of ecologically sensitive habitats for birds and fishes in Virginia requires a detailed understanding of the important changes in diet and migration over the life span of the animal. Stable isotope analysis offers the potential to assess migration and trophic level variability in birds and fishes from southeastern Virginia and the greater Chesapeake Bay. Fish of various species and ages from different locations throughout the Chesapeake Bay were analyzed for carbon-13 and nitrogen-15 bulk natural abundance. Of particular note, blue fish were found to have significantly higher d15N values than striped bass which are believed to be trophic competitors. Observations are discussed relative to the maturity of the different fish, variation in water-mass chemistry (N-inputs), local environmental habitats, trophic relationships and migratory habits. In conjunction with banding studies being conducted by Virginia Department of Game and Inland Fisheries in the Great Dismal Swamp (VA), breast feathers from Carolina Wren, Common Yellowthroat, Northern Cardinal, Ovenbird, and Prothonotary Warbler were analyzed for carbon-13 and nitrogen-15 bulk natural abundance. Given the preliminary nature of this work our ability to identify trends between species was less than satisfying, thus highlighting the need for larger sample populations over more than one breeding season. However, within a given species (most notably the Prothonotary Warbler) we are able to discern a change in diet. The hatching year Prothonotary warbler were more enriched in both carbon-13 and nitrogen-15 than the after-hatching-year (AHY) birds, indicating a change in food sources between the two age groups. By sampling over time and at various sample sites, isotopic analyses allow a more detailed investigation of the spatial and temporal variation in the diets and migratory habits of fishes and birds in Virginia and the Chesapeake Bay.

  5. Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon.

    PubMed

    Day, James M D; Moynier, Frederic

    2014-09-13

    The Moon is depleted in volatile elements relative to the Earth and Mars. Low abundances of volatile elements, fractionated stable isotope ratios of S, Cl, K and Zn, high ? ((238)U/(204)Pb) and long-term Rb/Sr depletion are distinguishing features of the Moon, relative to the Earth. These geochemical characteristics indicate both inheritance of volatile-depleted materials that formed the Moon and planets and subsequent evaporative loss of volatile elements that occurred during lunar formation and differentiation. Models of volatile loss through localized eruptive degassing are not consistent with the available S, Cl, Zn and K isotopes and abundance data for the Moon. The most probable cause of volatile depletion is global-scale evaporation resulting from a giant impact or a magma ocean phase where inefficient volatile loss during magmatic convection led to the present distribution of volatile elements within mantle and crustal reservoirs. Problems exist for models of planetary volatile depletion following giant impact. Most critically, in this model, the volatile loss requires preferential delivery and retention of late-accreted volatiles to the Earth compared with the Moon. Different proportions of late-accreted mass are computed to explain present-day distributions of volatile and moderately volatile elements (e.g. Pb, Zn; 5 to >10%) relative to highly siderophile elements (approx. 0.5%) for the Earth. Models of early magma ocean phases may be more effective in explaining the volatile loss. Basaltic materials (e.g. eucrites and angrites) from highly differentiated airless asteroids are volatile-depleted, like the Moon, whereas the Earth and Mars have proportionally greater volatile contents. Parent-body size and the existence of early atmospheres are therefore likely to represent fundamental controls on planetary volatile retention or loss. PMID:25114311

  6. Uplifting of palsa peatlands by permafrost identified by stable isotope depth profiles

    NASA Astrophysics Data System (ADS)

    Krüger, Jan Paul; Conen, Franz; Leifeld, Jens; Alewell, Christine

    2015-04-01

    Natural abundances of stable isotopes are a widespread tool to investigate biogeochemical processes in soils. Palsas are peatlands with an ice core and are common in the discontinuous permafrost region. Elevated parts of palsa peatlands, called hummocks, were uplifted by permafrost out of the influence of groundwater. Here we used the combination of ?15N values and C/N ratio along depth profiles to identify perturbation of these soils. In the years 2009 and 2012 we took in total 14 peat cores from hummocks in two palsa peatlands near Abisko, northern Sweden. Peat samples were analysed in 2 to 4 cm layers for stable isotope ratios and concentrations of C and N. The uplifting of the hummocks by permafrost could be detected by stable isotope depth patterns with the highest ?15N value at permafrost onset, a so-called turning point. Regression analyses indicated in 11 of 14 peat cores increasing ?15N values above and decreasing values below the turning point. This is in accordance with the depth patterns of ?13C values and C/N ratios in these palsa peatlands. Onset of permafrost aggradation identified by the highest ?15N value in the profile and calculated from peat accumulation rates show ages ranging from 80 to 545 years and indicate a mean (±SD) peat age at the turning points of 242 (±66) years for Stordalen and 365 (±53) years for Storflaket peatland. The mean peat ages at turning points are within the period of the Little Ice Age. Furthermore, we tested if the disturbance, in this case the uplifting of the peat material, can be displayed in the relation of ?15N and C/N ratio following the concept of Conen et al. (2013). In unperturbed sites soil ?15N values cover a relatively narrow range at any particular C/N ratio. Changes in N cycling, i.e. N loss or gain, results in the loss or gain of 15N depleted forms. This leads to larger or smaller ?15N values than usual at the observed C/N ratio. All, except one, turning point show a perturbation in the depth profile, with most of the adjacent sampling points also indicating perturbation. This perturbation shows the changes in N cycling, in this case N loss, from these depths due to permafrost aggradation. Deeper parts of some profiles at Stordalen peatland indicate with the same approach an N gain, maybe due to lateral N input to these nutrient poor ecosystems. Most of the uppermost samples in the ?15N depth profiles show no perturbation, potentially due to the adaptation of these soils to the new conditions. Both stable isotope (?15N and ?13C) depth profiles are suitable to detect palsa uplifting by permafrost. The perturbation of the peat by uplifting as well as the potential nutrient input can be detected by ?15N when related to the C/N ratio. Conen, F., Yakutin, M. V., Carle, N., and Alewell, C. (2013): ?15N natural abundance may directly disclose perturbed soil when related to C:N ratio. Rapid Commun. Mass Spectrom. 27: 1101-1104.

  7. s-process studies - Xenon and krypton isotopic abundances

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.; Ward, R. A.

    1978-01-01

    We propose an analysis of the s-process contributions to the isotopes of xenon and krypton. The object is to aid studies of the possibility that meteorites may contain gas that was carried in presolar grains that were grown in stellar ejecta and that were not degassed prior to incorporation into parent bodies. That model suggests routine interstellar fractionation of s-isotopes from r-isotopes owing to differential incorporation into dust. We show that a deficiency of s-process nuclei cannot yield details of Xe-X, but the gross similarities are strong enough to lead one to think that such a deficiency may play a role in a more complicated explanation. We predict the existence of an s-rich complement somewhere if fractional separation of this type has played a role in Xe-X. We show that the analogous decomposition of krypton is more uncertain, and we call for measurements of neutron-capture cross sections to alleviate these uncertainties.

  8. Stable Isotope Labeling of Phosphoproteins for Large-scale Phosphorylation Rate Determination*

    PubMed Central

    Molden, Rosalynn C.; Goya, Jonathan; Khan, Zia; Garcia, Benjamin A.

    2014-01-01

    Signals that control responses to stimuli and cellular function are transmitted through the dynamic phosphorylation of thousands of proteins by protein kinases. Many techniques have been developed to study phosphorylation dynamics, including several mass spectrometry (MS)-based methods. Over the past few decades, substantial developments have been made in MS techniques for the large-scale identification of proteins and their post-translational modifications. Nevertheless, all of the current MS-based techniques for quantifying protein phosphorylation dynamics rely on the measurement of changes in peptide abundance levels, and many methods suffer from low confidence in phosphopeptide identification due to poor fragmentation. Here we have optimized an approach for the stable isotope labeling of amino acids by phosphate using [?-18O4]ATP in nucleo to determine global site-specific phosphorylation rates. The advantages of this metabolic labeling technique are increased confidence in phosphorylated peptide identification, direct labeling of phosphorylation sites, measurement phosphorylation rates, and the identification of actively phosphorylated sites in a cell-like environment. In this study we calculated approximate rate constants for over 1,000 phosphorylation sites based on labeling progress curves. We measured a wide range of phosphorylation rate constants from 0.34 min?1 to 0.001 min?1. Finally, we applied stable isotope labeling of amino acids by phosphate to identify sites that have different phosphorylation kinetics during G1/S and M phase. We found that most sites had very similar phosphorylation rates under both conditions; however, a small subset of sites on proteins involved in the mitotic spindle were more actively phosphorylated during M phase, whereas proteins involved in DNA replication and transcription were more actively phosphorylated during G1/S phase. The data have been deposited to the ProteomeXchange with the identifier PXD000680. PMID:24532841

  9. Stable isotope labeling of phosphoproteins for large-scale phosphorylation rate determination.

    PubMed

    Molden, Rosalynn C; Goya, Jonathan; Khan, Zia; Garcia, Benjamin A

    2014-04-01

    Signals that control responses to stimuli and cellular function are transmitted through the dynamic phosphorylation of thousands of proteins by protein kinases. Many techniques have been developed to study phosphorylation dynamics, including several mass spectrometry (MS)-based methods. Over the past few decades, substantial developments have been made in MS techniques for the large-scale identification of proteins and their post-translational modifications. Nevertheless, all of the current MS-based techniques for quantifying protein phosphorylation dynamics rely on the measurement of changes in peptide abundance levels, and many methods suffer from low confidence in phosphopeptide identification due to poor fragmentation. Here we have optimized an approach for the stable isotope labeling of amino acids by phosphate using [?-¹?O?]ATP in nucleo to determine global site-specific phosphorylation rates. The advantages of this metabolic labeling technique are increased confidence in phosphorylated peptide identification, direct labeling of phosphorylation sites, measurement phosphorylation rates, and the identification of actively phosphorylated sites in a cell-like environment. In this study we calculated approximate rate constants for over 1,000 phosphorylation sites based on labeling progress curves. We measured a wide range of phosphorylation rate constants from 0.34 min?¹ to 0.001 min?¹. Finally, we applied stable isotope labeling of amino acids by phosphate to identify sites that have different phosphorylation kinetics during G1/S and M phase. We found that most sites had very similar phosphorylation rates under both conditions; however, a small subset of sites on proteins involved in the mitotic spindle were more actively phosphorylated during M phase, whereas proteins involved in DNA replication and transcription were more actively phosphorylated during G1/S phase. The data have been deposited to the ProteomeXchange with the identifier PXD000680. PMID:24532841

  10. Stable Isotope Analysis of a Middle Woodland Population from North Central Kansas

    E-print Network

    Kauffman, Greg

    2013-08-31

    This study sought to examine the paleodiet and temporality of a Middle Woodland group from five sites in north central Kansas. This goal was accomplished by submitting 21 samples for stable isotope ratios analysis (SIRA) ...

  11. Stable isotopes challenge the perception of ocean sunfish Mola mola as obligate jellyfish predators.

    PubMed

    Syväranta, J; Harrod, C; Kubicek, L; Cappanera, V; Houghton, J D R

    2012-01-01

    Evidence is provided from stable isotope analysis that aggregations of small ocean sunfish Mola mola (total length <1 m) feed broadly within coastal food webs and their classification as obligate predators of gelatinous zooplankton requires revision. PMID:22220901

  12. INCORPORATING CONCENTRATION DEPENDENCE IN STABLE ISOTOPE MIXING MODELS: A REPLY TO ROBBINS, HILDERBRAND AND FARLEY (2002)

    EPA Science Inventory

    Phillips & Koch (2002) outlined a new stable isotope mixing model which incorporates differences in elemental concentrations in the determinations of source proportions in a mixture. They illustrated their method with sensitivity analyses and two examples from the wildlife ecolog...

  13. SEASONAL VARIATIONS OF STABLE HYDROGEN AND CARBON ISOTOPE RATIOS OF METHANE IN SUBTROPICAL FRESHWATER SEDIMENTS

    EPA Science Inventory

    Stable hydrogen (D) and carbon (13C) isotope ratios of sedimentary methane from five subtropical Florida freshwater sites exhibited smaller, less distinct seasonal variations than previously observed in temperate sediments, apparently due to the smaller range of temperatures forc...

  14. Analysis of the ecology of Anchialine Caves using carbon and nitrogen stable isotopes 

    E-print Network

    Pohlman, John William

    1995-01-01

    Carbon and nitrogen stable isotopes were used to investigate the biogeochemical and ecological processes that govern anchialine cave ecosystems in the Yucatan Peninsula, Quintana Roo, Mexico. Anchialine caves are subterranean passages...

  15. Application of stable isotope techniques to characterize CO2 storage sites

    NASA Astrophysics Data System (ADS)

    Barth, J. A. C.; Becker, V.; Myrttinen, A.; Zimmer, M.; Nowak, M.

    2012-04-01

    Injection of CO2 into the subsurface causes geochemical changes of the water and its dissolved load. It also causes stable isotope alterations of dissolved inorganic carbon (DIC). If CO2 is present in large enough amounts, changes of the water isotope composition can also be expected. Therefore, stable isotope alterations provide additional tools to quantify turnover and interaction of the injected CO2. In a first step, the geochemistry and isotope composition of the undisturbed storage site fluids have to be characterized before injection. This implies careful retrieval of samples from depth in order to avoid pressure changes that might alter the isotope ratios of water or DIC. Reservoir fluids were sampled using an open flow-through sampler ('Doppelkugelbüchse', DKB), or a pressure-sealed Positive Displacement Sampler (PDS) and showed that pressure conservation becomes particularly important after injection of CO2 when pressure gradients between atmosphere and formation become more pronounced. Stable carbon isotope differences between the injected CO2 and the already present DIC helped to establish mass balances. These showed that up to 70 % of DIC after injection may consist of added CO2. Stable isotopes also established its own tracer when batches of injected CO2 had different isotope compositions. For instance, at the Ketzin site, a carbon isotope shift of the DIC of about 2 permille was found a few days after changeover of a gas from a different source with a distinct isotope ratio. This breakthrough coincided well with the ones of other implemented tracers (krypton and sulfurhexafluorid). The combination of stable isotopes and conservative tracers have therefore proven to be suitable tools for identifying different sources of CO2. They also help to trace migration behaviour and spreading of injected CO2 in a storage reservoir.

  16. Hydrogen isotopic composition of NBS and IAEA stable isotope water reference samples

    Microsoft Academic Search

    Tyler B. Coplen; Robert N. Clayton

    1973-01-01

    The hydrogen isotopic compositions of several isotope water reference samples have been determined on a cycloidal double-collecting isotope ratio mass spectrometer that can resolve HD + from the `contaminant' H 3 + ion beam.

  17. SILACAnalyzer - A Tool for Differential Quantitation of Stable Isotope Derived Data

    Microsoft Academic Search

    Lars Nilse; Marc Sturm; David C. Trudgian; Mogjiborahman Salek; Paul F. G. Sims; Kathleen M. Carroll; Simon J. Hubbard

    2009-01-01

    \\u000a Quantitative proteomics is a growing field where several experimental techniques such as those based around stable isotope\\u000a labelling are reaching maturity. These advances require the parallel development of informatics tools to process and analyse\\u000a the data, especially for high-throughput experiments seeking to quantify large numbers of proteins. We have developed a novel\\u000a algorithm for the quantitative analysis of stable isotope-based

  18. Food webs in subAntarctic lakes: a stable isotope approach

    Microsoft Academic Search

    Lars-Anders Hansson; Lars J. Tranvik

    2003-01-01

    In order to improve the understanding of food-web interactions in sub-Antarctic freshwater systems, we complemented earlier experimental studies with analyses of differences in stable isotopes ( 15N and 13C) among organisms in two lakes with contrasting productivity. The distribution of the stable isotopes showed that the small copepod Boeckella michaelseni feeds mainly on pelagic POM (particulate organic material), whereas the

  19. 2H Stable Isotope Analysis of Tooth Enamel: A Pilot Study

    Microsoft Academic Search

    Anastasia Holobinko; Helen Kemp; Wolfram Meier-Augenstein; Tracy Prowse; Susan Ford

    2010-01-01

    Stable isotope analysis of biogenic tissues such as tooth enamel and bone mineral has become a well recognized and increasingly important method for determining provenance of human remains, and has been used successfully in bioarchaeological studies as well as forensic investigations (Lee-Thorp, 2008; Meier-Augenstein and Fraser, 2008). Particularly, 18O and 2H stable isotopes are well established proxies as environmental indicators

  20. RNA Stable Isotope Probing, a Novel Means of Linking Microbial Community Function to Phylogeny

    Microsoft Academic Search

    Mike Manefield; Andrew S. Whiteley; Robert I. Griffiths; Mark J. Bailey

    2002-01-01

    accountable for it. In this study stable-isotope-labeled (13C)phenol was fed into a phenol-degrading community from an aerobic industrial bioreactor, and the 13C-labeled RNA produced was used to identify the bacteria responsible for the process. Stable-isotope-labeled RNA was analyzed by equilibrium density centrifugation in concert with reverse transcription-PCR and denaturing gradient gel electrophoresis. In contradiction with findings from conventional methodologies, this

  1. A practical recipe for stable isotope labeling by amino acids in cell culture (SILAC)

    Microsoft Academic Search

    Matthias Mann; Shao-En Ong

    2007-01-01

    Stable isotope labeling by amino acids in cell culture (SILAC) is a simple, robust, yet powerful approach in mass spectrometry (MS)-based quantitative proteomics. SILAC labels cellular proteomes through normal metabolic processes, incorporating non-radioactive, stable isotope-containing amino acids in newly synthesized proteins. Growth medium is prepared where natural (“light”) amino acids are replaced by “heavy” SILAC amino acids. Cells grown in

  2. A practical recipe for stable isotope labeling by amino acids in cell culture (SILAC)

    Microsoft Academic Search

    Shao-En Ong; Matthias Mann

    2006-01-01

    Stable isotope labeling by amino acids in cell culture (SILAC) is a simple, robust, yet powerful approach in mass spectrometry (MS)-based quantitative proteomics. SILAC labels cellular proteomes through normal metabolic processes, incorporating non-radioactive, stable isotope-containing amino acids in newly synthesized proteins. Growth medium is prepared where natural (''light'') amino acids are replaced by ''heavy'' SILAC amino acids. Cells grown in

  3. Natural abundances of carbon isotopes in acetate from a coastal marine sediment

    NASA Technical Reports Server (NTRS)

    Blair, N. E.; Martens, C. S.; Des Marais, D. J.

    1987-01-01

    Measurements of the natural abundances of carbon isotopes were made in acetate samples isolated from the anoxic marine sediment of Cape Lookout Bight, North Carolina. The typical value of the total acetate carbon isotope ratio (delta 13C) was -16.1 +/- 0.2 per mil. The methyl and carboxyl groups were determined to be -26.4 +/- 0.3 and -6.0 +/- 0.3 per mil, respectively, for one sample. The isotopic composition of the acetate is thought to have resulted from isotopic discriminations that occurred during the cycling of that molecule. Measurements of this type, which have not been made previously in the natural environment, may provide information about the dominant microbial pathways in anoxic sediments as well as the processes that influence the carbon isotopic composition of biogenic methane from many sources.

  4. Stable Isotope Ratios Using Cavity Ring-Down Spectroscopy: Determination of 13

    E-print Network

    Zare, Richard N.

    Stable Isotope Ratios Using Cavity Ring-Down Spectroscopy: Determination of 13 C/12 C for Carbon-down spectrometer employing a near-IR external cavity diode laser capable of measuring 13C/12C isotopic ratios in CO.2 × 10-11 cm-1 Hz-1/2, determines the isotopic ratio of 13C16O16O/12C16O16O by measuring the intensities

  5. Food web analysis of southern California coastal wetlands using multiple stable isotopes

    Microsoft Academic Search

    Thomas J. Kwak; Joy B. Zedler

    1997-01-01

    Carbon, nitrogen, and sulfur stable isotopes were used to characterize the food webs (i.e., sources of carbon and trophic\\u000a status of consumers) in Tijuana Estuary and San Dieguito Lagoon. Producer groups were most clearly differentiated by carbon,\\u000a then by sulfur, and least clearly by nitrogen isotope measurements. Consumer 15N isotopic enrichment suggested that there are four trophic levels in the

  6. Tunable diode laser absorption spectroscopy for stable isotope studies of ecosystem–atmosphere CO 2 exchange

    Microsoft Academic Search

    David R. Bowling; Steve D. Sargent; Bert D. Tanner; James R. Ehleringer

    2003-01-01

    The stable isotope content of atmospheric CO2 provides information about ecosystem carbon–water relations and biosphere–atmosphere carbon exchange. Virtually every isotope study within these fields has required air sample collection at remote locations followed by isotope analysis at a laboratory. This requirement severely limits sampling frequency and experiment duration. In this paper, we evaluate a tunable diode laser absorption spectrometer (TDL)

  7. Incorporation of a stable isotopically labeled amino acid into multiple human apolipoproteins

    Microsoft Academic Search

    Bruce W. Patterson; David L. Hachey; Gary L. Cook; Joseph M. Amann; Peter D. Klein

    Procedures are presented for the separation and de- termination of the isotopic enrichment of multiple human apoli- poproteins labeled in vivo with a stable isotope amino acid. The isotopic enrichments of plasma lysine and plasma apolipopro- teins were monitored for 16 days after a single intravenous dose of (4,4,5,5-2H4)lysine (5 mg\\/kg body weight). The use of a mul- tiply deuterated

  8. Differential host use in two highly specialized ant-plant associations: evidence from stable isotopes

    Microsoft Academic Search

    S. T. Trimble; C. L. Sagers

    2004-01-01

    Carbon and nitrogen stable isotopes were used to examine variation in ant use of plant resources in the Cecropia obtusifolia \\/ Azteca spp. association in Costa Rica. Tissue of ants, host plants and symbiotic pseudococcids were collected along three elevation transects on the Pacific slope of Costa Rica’s Cordillera Central, and were analyzed for carbon and nitrogen isotopic composition. Worker

  9. Stable Isotope Variations in Extraterrestrial Materials Kevin D. McKeegan 1

    E-print Network

    1 Stable Isotope Variations in Extraterrestrial Materials by Kevin D. McKeegan 1 and Laurie A the isotopic records of extraterrestrial materials range widely in environmental conditions from very high in the solar nebula to lower temperature fluid-rock interactions in asteroids and planets. In extraterrestrial

  10. Preservation methods alter stable isotope values in gelatinous zooplankton: implications for interpreting trophic ecology

    Microsoft Academic Search

    Nicholas E. C. Fleming; Jonathan D. R. Houghton; Caroline L. Magill; Chris Harrod

    2011-01-01

    Jellyfish are increasingly topical within studies of marine food webs. Stable isotope analysis represents a valuable technique to unravel the complex trophic role of these long-overlooked species. In other taxa, sample preservation has been shown to alter the isotopic values of species under consideration, potentially leading to misinterpretation of trophic ecology. To identify potential preservation effects in jellyfish, we collected

  11. Stable carbon isotope distributions of thermocatalytically generated low molecular weight hydrocarbon gases

    Microsoft Academic Search

    McCarty; H. B. Jr

    1984-01-01

    Laboratory simulations of petroleum formation were examined by stable carbon isotope studies of five cryogenic distillation fractions of the gases produced by thermal treatment of organic substrate. Simple heat treatment of substrates was contrasted with heat treatment in the presence of nickel and vanadium sulfides, ammonia, and water. Other reactions examined the effects of clay and carbonate on the isotopic

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

    Microsoft Academic Search

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

    1986-01-01

    A high degree of coherence in the annual stable isotopic records along different radial directions of a silver fir tree and between two members of this species from the Kashmir Valley has recently been reported by us. Since such a common pattern of isotopic variability is most likely due to the climatic fluctuations in the site, we have compared the

  13. Differentiating aquatic mammal habitat and foraging ecology with stable isotopes in tooth enamel

    Microsoft Academic Search

    Mark T. Clementz; Paul L. Koch

    2001-01-01

    We analyzed the carbon and oxygen isotope composition of tooth enamel from mammals inhabiting marine and terrestrial ecosystems to determine whether these stable isotopes were robust indicators of foraging and habitat preferences. Consumers were separated into six habitats (offshore, nearshore, kelp beds, estuarine, freshwater, terrestrial). Consumer ཉC values were correlated with the ཉC values of primary producers within each habitat,

  14. Stable isotope and Rare Earth Element evidence for recent ironstone pods within the Archean Barberton

    E-print Network

    Hren, Michael

    Stable isotope and Rare Earth Element evidence for recent ironstone pods within the Archean greenstone belt. We examined oxygen and hydrogen isotopes and Rare Earth Element (REE) concentrations pro- vide a valuable geochemical record of the conditions on the surface of the early Earth. Many

  15. Hydration in solution is critical for stable oxygen isotope fractionation between carbonate ion and water

    E-print Network

    Zeebe, Richard E.

    Hydration in solution is critical for stable oxygen isotope fractionation between carbonate ion fractionation factors (a's) between different chemical compounds in thermody- namic equilibrium. Although isotope fractionation between dissolved CO2À 3 and H2O (hereafter aðCO2À 3 ­H2OÞ). Simple force field

  16. More than who eats who: Discerning ecological processes from stable isotopes data

    EPA Science Inventory

    Stable isotope analyses of biota are now commonly used to discern trophic pathways between consumers and their foods. However, those same isotope data also hold information about processes that influence the physicochemical setting of food webs as well as biological processes ope...

  17. An introduction to stable water isotopes in climate models: benefits of forward proxy modelling for paleoclimatology

    Microsoft Academic Search

    C. Sturm; Q. Zhang; D. Noone

    2010-01-01

    Stable water isotopes have been measured in a wide range of climate archives, with the purpose of reconstructing regional climate variations. Yet the common assumption that the isotopic signal is a direct indicator of temperature proves to be misleading under certain circumstances, since its relationship with temperature also depends on e.g. atmospheric circulation and precipitation seasonality. Here we introduce the

  18. STABLE ISOTOPES IN ECOLOGICAL STUDIES: EXPANDING THE SCOPE OF MIXING MODELS

    EPA Science Inventory

    Stable isotopes are increasingly being used as tracers in ecological studies. One common application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include pollution sources for air or water bodies, food sources for an...

  19. Evolution of the Solar Nebula. VIII. Spatial and Temporal Heterogeneity of Short-Lived Radioisotopes and Stable Oxygen Isotopes

    E-print Network

    Alan P. Boss

    2007-02-02

    Isotopic abundances of short-lived radionuclides such as 26Al provide the most precise chronometers of events in the early solar system, provided that they were initially homogeneously distributed. On the other hand, the abundances of the three stable isotopes of oxygen in primitive meteorites show a mass-independent fractionation that survived homogenization in the solar nebula. As as result of this and other cosmochemical evidence, the degree of spatial heterogeneity of isotopes in the solar nebula has long been a puzzle. We show here that based on hydrodynamical models of the mixing and transport of isotopic anomalies formed at, or injected onto, the surface of the solar nebula, initially high levels of isotopic spatial heterogeneity are expected to fall to steady state levels (~10%) low enough to validate the use of 26Al for chronometry, but high enough to preserve the evidence for mass-independent fractionation of oxygen isotopes. The solution to this puzzle relies on the mixing being accomplished by the chaotic fluid motions in a marginally gravitationally unstable disk, as seems to be required for the formation of gas giant planets and by the inability of alternative physical processes to drive large-scale mixing and transport in the planet-forming midplane of the solar nebula. Such a disk is also capable of large-scale outward transport of the thermally annealed dust grains found in comets, and of driving the shock fronts that appear to be responsible for much of the thermal processing of the components of primitive meteorites, creating a self-consistent picture of the basic physical processes shaping the early solar nebula.

  20. Potassium stable isotopic compositions measured by high-resolution MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Morgan, L. E.; Lloyd, N. S.; Ellam, R. M.; Simon, J. I.

    2012-12-01

    Potassium isotopic (41K/39K) compositions are notoriously difficult to measure. TIMS measurements are hindered by variable fractionation patterns throughout individual runs and too few isotopes to apply an internal spike method for instrumental mass fractionation corrections. Internal fractionation corrections via the 40K/39K ratio can provide precise values but assume identical 40K/39K ratios (e.g. 0.05‰ (1?) in [1]); this is appropriate in some cases (e.g. identifying excess 41K) but not others (e.g., determining mass fractionation effects and metrologically traceable isotopic abundances). SIMS analyses have yielded measurements with 0.25‰ precisions (1?) [2]. ICP-MS analyses are significantly affected by interferences from molecular species such as 38ArH+ and 40ArH+ and instrument mass bias. Single collector ICP-MS instruments in "cold plasma" mode have yielded uncertainties as low as 2‰ (1?, e.g. [3]). Although these precisions may be acceptable for some concentration determinations, they do not resolve isotopic variation in terrestrial materials. Here we present data from a series of measurements made on the Thermo Scientific NEPTUNE Plus multi-collector ICP-MS that demonstrate the ability to make 41K/39K ratio measurements with 0.07‰ precisions (1?). These data, collected on NIST K standards, indicate the potential for MC-ICP-MS measurements to look for K isotopic variations at the sub-permil level. The NEPTUNE Plus can sufficiently resolve 39K and 41K from the interfering 38ArH+ and 40ArH+ peaks in wet cold plasma and high-resolution mode. Measurements were made on small but flat, interference-free, plateaus (ca. 50 ppm by mass width for 41K). Although ICP-MS does not yield accurate 41K/39K values due to significant instrumental mass fractionation (ca. 6%), this bias can be sufficiently stable over the time required for several measurements so that relative 41K/39K values can be precisely determined via sample-standard bracketing. As cold plasma conditions can amplify matrix effects, experiments were conducted to test the matrix tolerance of measurements; the use of clean, matrix-matched samples and standards is critical. Limitations of the cold-plasma high-resolution MC-ICP-MS methodology with respect to matrix tolerance are discussed and compared with the limitations of TIMS methodologies. References: [1] Wielandt and Bizzarro, 2011. [2] Humayun and Clayton, 1995. [3] Murphy et al., 2002.

  1. Potassium Stable Isotopic Compositions Measured by High-Resolution MC-ICP-MS

    NASA Technical Reports Server (NTRS)

    Morgan, Leah E.; Lloyd, Nicholas S.; Ellam, Robert M.; Simon, Justin I.

    2012-01-01

    Potassium isotopic (K-41/K-39) compositions are notoriously difficult to measure. TIMS measurements are hindered by variable fractionation patterns throughout individual runs and too few isotopes to apply an internal spike method for instrumental mass fractionation corrections. Internal fractionation corrections via the K-40/K-39 ratio can provide precise values but assume identical K-40/K-39 ratios (e.g. 0.05% (1sigma) in [1]); this is appropriate in some cases (e.g. identifying excess K-41) but not others (e.g., determining mass fractionation effects and metrologically traceable isotopic abundances). SIMS analyses have yielded measurements with 0.25% precisions (1sigma) [2]. ICP-MS analyses are significantly affected by interferences from molecular species such as Ar-38H(+) and Ar-40H(+) and instrument mass bias. Single collector ICP-MS instruments in "cold plasma" mode have yielded uncertainties as low as 2% (1sigma, e.g. [3]). Although these precisions may be acceptable for some concentration determinations, they do not resolve isotopic variation in terrestrial materials. Here we present data from a series of measurements made on the Thermo Scientific NEPTUNE Plus multi-collector ICP-MS that demonstrate the ability to make K-41/K-39 ratio measurements with 0.07% precisions (1sigma). These data, collected on NIST K standards, indicate the potential for MC-ICP-MS measurements to look for K isotopic variations at the sub-permil level. The NEPTUNE Plus can sufficiently resolve 39K and 41K from the interfering 38ArH+ and 40ArH+ peaks in wet cold plasma and high-resolution mode. Measurements were made on small but flat, interference-free, plateaus (ca. 50 ppm by mass width for K-41). Although ICP-MS does not yield accurate K-41/K-39 values due to significant instrumental mass fractionation (ca. 6%), this bias can be sufficiently stable over the time required for several measurements so that relative K-41/K-39 values can be precisely determined via sample-standard bracketing. As cold plasma conditions can amplify matrix effects, experiments were conducted to test the matrix tolerance of measurements; the use of clean, matrix-matched samples and standards is critical. Limitations of the cold-plasma high-resolution MC-ICP-MS methodology with respect to matrix tolerance are discussed and compared with the limitations of TIMS methodologies.

  2. Heterogeneity in the nebula - Evidence from stable isotopes

    NASA Technical Reports Server (NTRS)

    Thiemens, Mark H.

    1988-01-01

    Meteoritic isotopic evidence, primarily for O, which defines the existence of different nebular reservoirs, is analyzed. The internal isotopic systematics (for chondrules and incisions) is analyzed as well as its role in placing restraints on conditions and processes in the solar nebula. Questions pertaining to the actual origin of these reservoirs are addressed.

  3. Stable isotopes in late Pennsylvanian brachiopods: stratigraphic and paleoenvironmental implications 

    E-print Network

    Zhang, Chuanlun

    1989-01-01

    difference between replicates of 5tfO and 513C is no larger than 0. 5%o. By using averages of two or more shells, the effect of carbon and oxygen isotope variabilities between specimens on isotopic stratigraphy interpretation is minimal. Furthermore...

  4. Lichens and atmospheric sulphur: what stable isotopes reveal

    Microsoft Academic Search

    Moire A Wadleigh

    2003-01-01

    Isotopic compositions and total sulphur (S) levels were measured in Alectoria sarmentosa collected from over 80 sites on the island of Newfoundland, Canada. The spatial distribution of isotopic compositions of all samples is consistent with contributions of S from sea spray, local point sources and minor long-range transport. Thalli of A. sarmentosa were also transplanted from a relatively pristine area

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

    PubMed Central

    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 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 ?13C and ?15N 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 inte-grated in animals’ isotope values will be crucial for developing reliable methods to use stable isotopes as dietary tracers. PMID:25700080

  6. Stable water isotope and surface heat flux simulation using ISOLSM: Evaluation against in-situ measurements

    NASA Astrophysics Data System (ADS)

    Cai, Mick Y.; Wang, Lixin; Parkes, Stephen D.; Strauss, Josiah; McCabe, Matthew F.; Evans, Jason P.; Griffiths, Alan D.

    2015-04-01

    The stable isotopes of water are useful tracers of water sources and hydrological processes. Stable water isotope-enabled land surface modeling is a relatively new approach for characterizing the hydrological cycle, providing spatial and temporal variability for a number of hydrological processes. At the land surface, the integration of stable water isotopes with other meteorological measurements can assist in constraining surface heat flux estimates and discriminate between evaporation (E) and transpiration (T). However, research in this area has traditionally been limited by a lack of continuous in-situ isotopic observations. Here, the National Centre for Atmospheric Research stable isotope-enabled Land Surface Model (ISOLSM) is used to simulate the water and energy fluxes and stable water isotope variations. The model was run for a period of one month with meteorological data collected from a coastal sub-tropical site near Sydney, Australia. The modeled energy fluxes (latent heat and sensible heat) agreed reasonably well with eddy covariance observations, indicating that ISOLSM has the capacity to reproduce observed flux behavior. Comparison of modeled isotopic compositions of evapotranspiration (ET) against in-situ Fourier Transform Infrared spectroscopy (FTIR) measured bulk water vapor isotopic data (10 m above the ground), however, showed differences in magnitude and temporal patterns. The disparity is due to a small contribution from local ET fluxes to atmospheric boundary layer water vapor (?1% based on calculations using ideal gas law) relative to that advected from the ocean for this particular site. Using ISOLSM simulation, the ET was partitioned into E and T with 70% being T. We also identified that soil water from different soil layers affected T and E differently based on the simulated soil isotopic patterns, which reflects the internal working of ISOLSM. These results highlighted the capacity of using the isotope-enabled models to discriminate between different hydrological components and add insight into expected hydrological behavior.

  7. Measurement of very low stable isotope enrichments by gas chromatography/mass spectrometry: application to measurement of muscle protein synthesis.

    PubMed

    Patterson, B W; Zhang, X J; Chen, Y; Klein, S; Wolfe, R R

    1997-08-01

    Measurement of muscle protein synthesis using stable isotopically labeled tracers usually requires isotope ratio mass spectrometry (IRMS) because of the need to measure very low enrichments of stable isotopically labeled tracers (tracer to tracee ratio [TTR], 0.005% to 0.10%). This approach is laborious, requiring purification of the metabolite of interest and combustion to a gas for IRMS analysis, and is best suited for use with 13C tracers. We have developed an approach whereby low enrichments can be conveniently measured by a conventional gas chromatography/mass spectrometry (GC/MS) instrument. The approach includes three critical elements: (1) use of a highly substituted tracer containing three or more labeled atoms, to measure enrichment above a very low natural abundance of highly substituted isotopomers; (2) use of a highly substituted natural abundance isotopomer as a base ion for comparison rather than the most abundant m + 0 isotopomer, to reduce the dynamic range of the isotopomer ratio measurement; and (3) a sensitive mass spectrometric analysis that measures the natural abundance of the isotopomer used as a tracer with a high signal to noise ratio (> 100:1). This approach was used to measure the rate of synthesis of muscle protein following a primed continuous infusion of L-[13C6]-phenylalanine (PHE) in eight fasted dogs and L-[2H3]-leucine in five fasted human subjects. Values for [13C6]-PHE enrichment by GC/MS rates were virtually identical to those obtained by a conventional approach using high-performance liquid chromatography (HPLC) to isolate PHE, combustion to CO2, and measurement of 13CO2 enrichment by IRMS (IRMS enrichment = 0.9988 x GC/MS enrichment, R2 = .891), resulting in identical values for muscle fractional synthesis rates ([FSRs] mean +/- SEM: 2.7 +/- 0.2 and 2.5 +/- 0.2%/d for GC/MS and IRMS, respectively). Human muscle synthesis rates measured by GC/MS analysis of [2H3]-leucine enrichment (1.90 +/- 0.17%/d) were similar to published values based on IRMS analysis using a 1- 13C-leucine tracer. We conclude that compared with the IRMS approach, the GC/MS approach offers faster throughput, has a lower sample requirement, and is suitable for a wider variety of tracers such as 2H. The principles outlined here should be applicable to the measurement of low enrichments by GC/MS in a wide variety of stable isotope tracer applications. PMID:9258279

  8. Stable isotopic analysis of pyrogenic organic matter in soils by liquid chromatography-isotope-ratio mass spectrometry of benzene polycarboxylic acids.

    PubMed

    Yarnes, Christopher; Santos, Fernanda; Singh, Nimisha; Abiven, Samuel; Schmidt, Michael W I; Bird, Jeffrey A

    2011-12-30

    Pyrogenic organic matter (PyOM), the incomplete combustion product of organic materials, is considered stable in soils and represents a potentially important terrestrial sink for atmospheric carbon dioxide. One well-established method of measuring PyOM in the environment is as benzene polycarboxylic acids (BPCAs), a compound-specific method, which allows both qualitative and quantitative estimation of PyOM. Until now, stable isotope measurement of PyOM carbon involved measurement of the trimethylsilyl (TMS) or methyl (Me) polycarboxylic acid derivatives by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). However, BPCA derivatives can contain as much as 150% derivative carbon, necessitating post-analysis correction for the accurate measurement of ?¹³C values, leading to increased measurement error. Here, we describe a method for ?¹³C isotope ratio measurement and quantification of BPCAs from soil-derived PyOM, based on ion-exchange chromatography (IEC-IRMS). The reproducibility of the ?¹³C measurement of individual BPCAs by IEC-IRMS was better than 0.35‰ (1?). The ?¹³C-BPCA analysis of PyOM in soils, including at natural and artificially enriched ¹³C-abundance, produced accurate and precise ?¹³C measurements. Analysis of samples that differed in ?¹³C by as much as 900‰ revealed carryover of <1‰ between samples. The weighted sum of individual ?¹³C-BPCA measurements was correlated with previous isotopic measurements of whole PyOM, providing complementary information for bulk isotopic measurements. We discuss potential applications of ?¹³C-BPCA measurements, including the study of turnover rates of PyOM in soils and the partitioning of PyOM sources based on photosynthetic pathways. PMID:22468329

  9. Stable-carbon isotope variability in tree foliage and wood. [Iunipeus; Pinus edulis

    SciTech Connect

    Leavitt, S.W.; Long, A.

    1986-08-01

    This study documents variation of stable-carbon isotope ratios (/sup 13/C//sup 12/C) 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.

  10. Upper limits on argon isotope abundances in the Venus thermosphere

    NASA Technical Reports Server (NTRS)

    Mauersberger, K.; Von Zahn, U.; Krankowsky, D.

    1979-01-01

    On December 9, 1978 the neutral gas mass spectrometer aboard the NASA Pioneer Venus multiprobe bus has measured density, composition, and temperature of the Venus dayside thermosphere. There was no positive identification of argon down to the lowest measuring altitude of 130 km. For the altitude level of 135 km the following upper limits for the number densities of argon isotopes were derived: n(Ar-36) less than 1.3 times 10 to the 6th power per cu cm and n(Ar-40) less than 2.8 times 10 to the 6th power per cu cm. From our upper atmosphere observations we infer for the troposphere of Venus the following upper limits for the mixing ratios: n(Ar-36)/total number density less than 9 times 10 to the minus 6th power and n(Ar-40)/total number density less than 20 times 10 to the minus 6th power.

  11. Stable Isotope Mixing Models as a Tool for Tracking Sources of Water and Water Pollutants

    EPA Science Inventory

    One goal of monitoring pollutants is to be able to trace the pollutant to its source. Here we review how mixing models using stable isotope information on water and water pollutants can help accomplish this goal. A number of elements exist in multiple stable (non-radioactive) i...

  12. Evidence for deep mantle convection and primordial heterogeneity from nitrogen and carbon stable isotopes in diamond

    E-print Network

    Cartigny, Pierre

    Evidence for deep mantle convection and primordial heterogeneity from nitrogen and carbon stable September 2012 Communicated by: B. Marty Available online 23 October 2012 Keywords: mantle volatiles stable isotopes mantle convection diamonds primordial heterogeneity a b s t r a c t Diamond, as the deepest sample

  13. Origin of petroporphyrins. 2. Evidence from stable carbon isotopes.

    PubMed

    Boreham, C J; Fookes, C J; Popp, B N; Hayes, J M

    1990-01-01

    Compared with the carbon-13 isotopic composition of the ubiquitous C32DPEP (DPEP, deoxophylloerythroetioporphyrin) the heavy but equivalent carbon-13 isotopic composition for the porphyrin structures 15(2)-methyl-15,17-ethano-17-nor-H-C30DPEP and 15,17-butano-, 13,15-ethano-13(2),17-propano-, and 13(1)-methyl-13,15-ethano-13(2),17-propanoporphyrin suggests a common precursor, presumably chlorophyll c, for these petroporphyrins isolated from the marine Julia Creek oil shale and the lacustrine Condor oil shale. Similarly, the heavy but variable carbon-13 isotopic composition of 7-nor-H-C31DPEP compared with C32DPEP is consistent with an origin from both chlorophyll b and chlorophyll c3. The equivalent carbon-13 isotopic composition for 13(2)-methyl-C33DPEP compared with C32DPEP suggests a common origin resulting from a weighted average of chlorophyll inputs. PMID:11538479

  14. Stable-isotope geochronology of the Australian regolith

    SciTech Connect

    Bird, M.I.; Chivas, A.R. (Australian National Univ., Canberra (Australia))

    1989-12-01

    Australian regolith profiles can be assigned to one of three post-Palaeozoic age groups on the basis of the oxygen-isotope composition of authigenic clay minerals developed in the profile. Systematic variations in the isotopic composition of meteoric waters, and therefore of the authigenic regolith minerals that formed in equilibrium with them, are a result of the continent's drift from high to low latitudes and changes in global climate. The hydrogen-isotope composition of the clays range from -115 to -50{per thousand}; however, it is inferred that the majority of clays have undergone some post-formational hydrogen-isotope exchange which renders their {delta}D composition unsuitable for dating purposes.

  15. Production of stable isotope-labeled acyl-coenzyme A thioesters by yeast stable isotope labeling by essential nutrients in cell culture.

    PubMed

    Snyder, Nathaniel W; Tombline, Gregory; Worth, Andrew J; Parry, Robert C; Silvers, Jacob A; Gillespie, Kevin P; Basu, Sankha S; Millen, Jonathan; Goldfarb, David S; Blair, Ian A

    2015-04-01

    Acyl-coenzyme A (CoA) thioesters are key metabolites in numerous anabolic and catabolic pathways, including fatty acid biosynthesis and ?-oxidation, the Krebs cycle, and cholesterol and isoprenoid biosynthesis. Stable isotope dilution-based methodology is the "gold standard" for quantitative analyses by mass spectrometry. However, chemical synthesis of families of stable isotope-labeled metabolites such as acyl-CoA thioesters is impractical. Previously, we biosynthetically generated a library of stable isotope internal standard analogs of acyl-CoA thioesters by exploiting the essential requirement in mammals and insects for pantothenic acid (vitamin B5) as a metabolic precursor for the CoA backbone. By replacing pantothenic acid in the cell medium with commercially available [(13)C3(15)N1]-pantothenic acid, mammalian cells exclusively incorporated [(13)C3(15)N1]-pantothenate into the biosynthesis of acyl-CoA and acyl-CoA thioesters. We have now developed a much more efficient method for generating stable isotope-labeled CoA and acyl-CoAs from [(13)C3(15)N1]-pantothenate using stable isotope labeling by essential nutrients in cell culture (SILEC) in Pan6-deficient yeast cells. Efficiency and consistency of labeling were also increased, likely due to the stringently defined and reproducible conditions used for yeast culture. The yeast SILEC method greatly enhances the ease of use and accessibility of labeled CoA thioesters and also provides proof of concept for generating other labeled metabolites in yeast mutants. PMID:25572876

  16. A Test of Carbon and Oxygen Stable Isotope Ratio Process Models in Tree Rings.

    NASA Astrophysics Data System (ADS)

    Roden, J. S.; Farquhar, G. D.

    2008-12-01

    Stable isotopes ratios of carbon and oxygen in tree ring cellulose have been used to infer environmental change. Process-based models have been developed to clarify the potential of historic tree ring records for meaningful paleoclimatic reconstructions. However, isotopic variation can be influenced by multiple environmental factors making simplistic interpretations problematic. Recently, the dual isotope approach, where the variation in one stable isotope ratio (e.g. oxygen) is used to constrain the interpretation of variation in another (e.g. carbon), has been shown to have the potential to de-convolute isotopic analysis. However, this approach requires further testing to determine its applicability for paleo-reconstructions using tree-ring time series. We present a study where the information needed to parameterize mechanistic models for both carbon and oxygen stable isotope ratios were collected in controlled environment chambers for two species (Pinus radiata and Eucalyptus globulus). The seedlings were exposed to treatments designed to modify leaf temperature, transpiration rates, stomatal conductance and photosynthetic capacity. Both species were grown for over 100 days under two humidity regimes that differed by 20%. Stomatal conductance was significantly different between species and for seedlings under drought conditions but not between other treatments or humidity regimes. The treatments produced large differences in transpiration rate and photosynthesis. Treatments that effected photosynthetic rates but not stomatal conductance influenced carbon isotope discrimination more than those that influenced primarily conductance. The various treatments produced a range in oxygen isotope ratios of 7 ‰. Process models predicted greater oxygen isotope enrichment in tree ring cellulose than observed. The oxygen isotope ratios of bulk leaf water were reasonably well predicted by current steady-state models. However, the fractional difference between models that predict bulk leaf water versus the site of evaporation did not increase with transpiration rates. In conclusion, although the dual isotope approach may better constrain interpretation of isotopic variation, more work is required before its predictive power can be applied to tree-ring archives.

  17. Environmental geochemistry of calcium isotopes: Applications of a new stable isotope approach

    Microsoft Academic Search

    Zhanmin Liu; Congqiang Liu; Guilin Han; Zhongliang Wang; Zichen Xue; Zhaoliang Song; Cheng Yang

    2006-01-01

    This paper summarizes isotope fractionation mechanism, analytical method and applications in environmental geochemistry of\\u000a calcium isotopes. Calcium isotopic composition can be used to constrain material sources and study geological and environmental\\u000a processes as the isotopic composition of calcium (?44Ca) and fractionation processes depend on geochemical circumstances in nature. Recently, thanks to current advances in analytical\\u000a technology of calcium isotopes, calcium

  18. Stable calcium isotopic composition of meteorites and rocky planets

    Microsoft Academic Search

    Justin I. Simon; Donald J. DePaolo

    2010-01-01

    New measurements of mass-dependent calcium isotope effects in meteorites, lunar and terrestrial samples show that Earth, Moon, Mars, and differentiated asteroids (e.g., 4-Vesta and the angrite and aubrite parent bodies) are indistinguishable from primitive ordinary chondritic meteorites at our current analytical resolution (±0.07‰ SD for the 44Ca\\/40Ca ratio). In contrast, enstatite chondritic meteorites are slightly enriched in heavier calcium isotopes

  19. Lipid Biomarkers and Stable Isotope Signatures of Microbial Mats in Hot Springs of Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Romanek, C. S.; Mills, G. L.; Jones, M. E.; Paddock, L.; Li, Y.; Zhang, C. L.; Wiegel, J.

    2004-12-01

    Various hot springs of the Uzon Caldera, Kamchatka, were analyzed for their chemical and stable isotope composition to better understand the relationship(s) between thermophilic microorganisms and the environments in which they live. The springs had water temperatures ranging from 40-90\\deg C and pH ranging from 5.6-5.9. Gases that emanated from the springs were composed predominantly of CO2 (20 to 90%), with lesser amounts of CH4, (< 20%), H2, NH3 and SO2. Because the springs were acidic, they contained little dissolved inorganic carbon (DIC: millimol L-1) and sulfide (< 200 ppb), yet in some cases where microbial activity was relatively high, these constituents reached the millimol L-1 and ppm range, respectively. Total biomass displayed a relatively large range of carbon isotope compositions that ranged from -5.7 to -22.4 per mil, which may reflect the large range of carbon sources, varied CO2 fixation pathways, or other unknown mechanisms. Microbial mats were freeze-dried and extracted for lipid biomarker analysis. The lipids were separated into hydrocarbon, sterol, ether lipid, free fatty acid, and phospholipid fatty acid (PLFA) fractions. Among these fractions, PLFA indicated the community structure and abundance for Bacteria while the ether lipid fraction provided analogous information for Archaea. Results of PLFA showed 16:0 as the most abundant fatty acid (33-44%), which is universal in all living organisms. Other significant biomarkers included 18:1? (19 to 24%), 18:2? (5 to 13%), 16:1? (3 to 12%), and 18:0 (2 to 7%). These biomarkers are characteristic of cyanobacteria, green-sulfur bacteria, and green non-sulfur bacteria, respectively, which are common autotrophic organisms in terrestrial hot springs. On the other hand, biomarkers of heterotrophic bacteria, such as iso- and anteiso-15:0 were low (2-8%), indicating that the bacterial carbon cycle was dominated by autotrophic organisms. Analogous archaeal constituents were present in significant abundance in the ether lipids fraction.

  20. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to ...

  1. FISH AND SHRIMP MIGRATIONS IN THE NORTHERN GULF OF MEXICO ANALYZED USING STABLE C,N, ANDS ISOTOPE RATIOS1

    E-print Network

    FISH AND SHRIMP MIGRATIONS IN THE NORTHERN GULF OF MEXICO ANALYZED USING STABLE C,N, ANDS ISOTOPE RATIOS1 BRIAN FRY' ABSTRACT Natural stable isotope tags were used in the northern Gulfof/atus, Penaeus aztecus, P. duorarum, and P. setiferus. Along the south Texas and Florida coasts, isotopic

  2. Evaluation of the Variation in Sample Preparation for Comparative Proteomics Using Stable Isotope Labeling by Amino Acids in Cell

    E-print Network

    Chait, Brian T.

    with sample preparation. In this study, we report the strategy of using SILAC (stable isotope labeling on quantitative accuracy. For example, for approaches based on stable isotope labeling, the "light" and "heavy" samples can be mixed after differential isotope labeling so that subsequent sample handling will introduce

  3. Stable Carbon and Nitrogen Isotope Ratios of Sodium and Potassium Cyanide as a Forensic Signature

    SciTech Connect

    Kruzer, Helen W [Pacific Northwest National Laboratory (PNNL); Horita, Juske [ORNL; Moran, James J [Pacific Northwest National Laboratory (PNNL); Tomkins, Bruce A [ORNL; Janszen, Derek B [Pacific Northwest National Laboratory (PNNL); Carman, April [Pacific Northwest National Laboratory (PNNL)

    2012-01-01

    Sodium and potassium cyanide are highly toxic, produced in large amounts by the chemical industry, and linked to numerous high-profile crimes. The U.S. Centers for Disease Control and Prevention has identified cyanide as one of the most probable agents to be used in a future chemical terrorism event. We investigated whether stable C and N isotopic content of sodium and potassium cyanide could serve as a forensic signature for sample matching, using a collection of 65 cyanide samples. A few of these samples displayed non-homogeneous isotopic content associated with degradation to a carbonate salt and loss of hydrogen cyanide. Most samples had highly reproducible isotope content. Of these, >95% could be properly matched based on C and N isotope ratios, with a false match rate <3%. These results suggest that stable C and N isotope ratios are a useful forensic signature for matching cyanide samples.

  4. Stable Carbon and Nitrogen Isotope Ratios of Sodium and Potassium Cyanide as a Forensic Signature

    SciTech Connect

    Kreuzer, Helen W.; Horita, Juske; Moran, James J.; Tomkins, Bruce; Janszen, Derek B.; Carman, April J.

    2012-01-03

    Sodium and potassium cyanide are highly toxic, produced in large amounts by the chemical industry, and linked to numerous high-profile crimes. The U.S. Centers for Disease Control and Prevention has identified cyanide as one of the most probable agents to be used in a future chemical terrorism event. We investigated whether stable C and N isotopic content of sodium and potassium cyanide could serve as a forensic signature for sample matching, using a collection of 65 cyanide samples. A few of these samples displayed non-homogeneous isotopic content associated with degradation to a carbonate salt and loss of hydrogen cyanide. Most samples had highly reproducible isotope content. Of these, >95% could be properly matched based on C and N isotope ratios, with a false match rate <3%. These results suggest that stable C and N isotope ratios are a useful forensic signature for matching cyanide samples.

  5. Classification of Chinese Honeys According to Their Floral Origins Using Elemental and Stable Isotopic Compositions.

    PubMed

    Wu, Zhaobin; Chen, Lanzhen; Wu, Liming; Xue, Xiaofeng; Zhao, Jing; Li, Yi; Ye, Zhihua; Lin, Guanghui

    2015-06-10

    The objective of this study is to test the feasibility of multi-isotopic and elemental analyses combined with chemometric techniques for differentiating the botanical origins of major honey products in China. The stable isotope and elemental compositions of 57 honey samples from four major floral origins in China (i.e., rape honey, acacia honey, vitex honey, and jujube honey) were analyzed using stable isotope ratio mass spectrometry (IRMS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results showed that hydrogen and oxygen isotopes could be more suitable than the carbon isotope for discriminating the floral origins of major honeys in China. There were significant differences in the contents of most elements between or among different floral origins. The combination of IRMS and ICP-MS methods provides the most effective and accurate approach (in most cases close to 100% accuracy) for classifying Chinese honeys according to their floral origins. PMID:25990572

  6. Plasma separation process facility for large-scale stable isotope production

    SciTech Connect

    Bigelow, T.S.; Collins, E.D.; Tracy, J.G. [Oak Ridge National Lab., TN (United States)

    1997-12-01

    A facility for large-scale separation of stable isotopes using the plasma separation process (PSP) is under development at the Oak Ridge National Laboratory. The PSP is capable of separating isotopes at a large throughput rate with medium purity product and at relatively low cost. The PSP has a number of convenient features that make it an attractive technology for general isotope separation purposes. Several isotopes for medical and industrial applications, including {sup 102}Pd, {sup 98}Mo, {sup 203}Tl, {sup 184}W, and others, are expected to be processed in this facility. The large throughput and low processing cost of the PSP will likely lead to new applications for stable isotopes. A description of this facility and its typical throughput capability is presented here.

  7. Isotopic and speciation study on cerium during its solid-water distribution with implication for Ce stable isotope as a paleo-redox proxy

    NASA Astrophysics Data System (ADS)

    Nakada, Ryoichi; Takahashi, Yoshio; Tanimizu, Masaharu

    2013-02-01

    Cerium (Ce) has anomalously high or low concentrations relative to its neighboring elements, lanthanum (La) and praseodymium (Pr), because of its chemical properties; this phenomenon is known as the Ce anomaly. This redox-sensitive property of Ce allows the estimation of the redox state of paleo-ocean environments and the evolution of the atmosphere. However, a consideration of only the relative abundance of Ce may lead to an incomplete understanding of its oxidation process. In the current study, three important geochemical parameters, namely, abundance, stable isotope ratio, and chemical speciation, were obtained for Ce to derive more information from the Ce anomaly. In our adsorption experiments, the distribution pattern of rare earth elements (REEs) suggests the oxidative scavenging of Ce by ?-MnO2. This finding is further supported by the presence of Ce(IV), as detected by the X-ray absorption near-edge structure (XANES) spectra, which is in agreement with previous studies. However, the REE distribution pattern combined with the XANES spectra of the Ce adsorbed on ferrihydrite indicated that Ce may not have been oxidized by ferrihydrite in the Ce/ferrihydrite system during our experimental period. Assuming equilibrium fractionation, the mean isotopic fractionation factors between the liquid and solid phases (?Lq-So) of (i) Ce adsorbed on ferrihydrite, (ii) spontaneous precipitation of Ce, and (iii) Ce adsorbed on ?-MnO2 were 1.000145 (±0.000022), 1.000196 (±0.000031), and 1.000411 (±0.000079), respectively. These results indicate that the degree of isotopic fractionation of Ce between the liquid and solid phases becomes larger as the redox condition becomes more oxic in the following order: adsorption without oxidation < spontaneous precipitation < oxidative adsorption. Previously, the appearance of the Ce anomaly and/or XANES analysis constituted the only tool available for exploring the redox state. This study, however, suggests that the stable isotope ratio of Ce can be used to clearly distinguish spontaneous precipitation from oxidative adsorption on ?-MnO2, that occur under more oxic conditions than the Ce(III)/Ce(IV) boundary. Although similar experiments need to be done in a system more similar to natural systems, our results suggest that the combination of the stable isotope ratio and chemical state of Ce can be used to classify the redox condition into three stages based on Ce geochemistry, thereby offering a powerful tool for exploring redox conditions in paleo-ocean environments.

  8. Stable isotopes as tracers of organic matter input and transfer in benthic food webs: A review

    NASA Astrophysics Data System (ADS)

    Peterson, Bruce J.

    1999-07-01

    Some of the ways that the application of stable isotopic tracers have contributed to the extremely hard task of understanding the energy and food web relations in benthic communities are illustrated in this review. Several methods are presented and their relative advantages are discussed, namely the use of endmembers, nitrogen isotopes, carbon isotopes, and sulfur isotopes. Special attention is given to the application of multiple tracers and transects sampling, natural and man-made perturbation experiments, and 15N additions as N cycle tracers.

  9. On the enrichment of low-abundant isotopes of light chemical elements by gas centrifuges

    NASA Astrophysics Data System (ADS)

    Borisevich, V. D.; Morozov, O. E.; Zaozerskiy, Yu. P.; Shmelev, G. M.; Shipilov, Yu. D.

    2000-08-01

    A brief review of the main areas for the application of the isotopes 15N and 13C is made. Separation of the nitrogen isotopes in a single gas centrifuge in the form of pure nitrogen, ammonia, and trifluoride of nitrogen as well as the carbon isotopes in the form of carbon dioxide has been studied by means of numerical simulation. The parameters of the centrifugal machine investigated were close to the parameters of the Iguassu machine. The dependence of the efficiency criterion versus the basic parameters of the separation process has been explored in the computational experiments. Comparisons of the calculated results with the experimental data have shown good agreement. The results obtained have demonstrated the possibility of using gas centrifuge technology to enrich successfully the low-abundant isotopes of light chemical elements.

  10. Stable isotopes of authigenic minerals in variably-saturated fractured tuff

    SciTech Connect

    Weber, D.S.; Evans, D.D.

    1988-11-01

    Identifying stable isotope variation and mineralogical changes in fractured rock may help establish the history of climatic and geomorphological processes that might affect the isolation properties of a waste repository site. This study examines the use of the stable isotope ratios of oxygen ({sup 18}O/{sup 16}O) and carbon ({sup 13}C/{sup 12}C) in authigenic minerals as hydrogeochemical tools tracing low-temperature rock-water interaction in variably-saturated fractured stuff. Isotopic compositions of fracture-filling and rock matrix minerals in the Apache Leap tuff, near Superior, Arizona were concordant with geothermal temperatures and in equilibrium with water isotopically similar to present-day meteoric water and groundwater. Oxygen and carbon isotope ratios of fracture-filling, in unsaturated fractured tuff, displayed an isotopic gradient believed to result from near-surface isotopic enrichment due to evaporation rather than the effects of rock-water interaction. Oxygen isotope ratios of rock matrix opal samples exhibited an isotopic gradient believed to result from, leaching and reprecipitation of silica at depth. Methods and results can be used to further define primary flowpaths and the movement of water in variably-saturated fractured rock. 71 refs., 23 figs., 3 tabs.

  11. Uptake of Dissolved Sulfide by Spartina alterniflora: Evidence from Natural Sulfur Isotope Abundance Ratios

    Microsoft Academic Search

    Paul R. Carlson; Joseph Forrest

    1982-01-01

    The difference in the stable sulfur isotope ratios of sulfate and sulfide in marsh pore water was used to verify the uptake of hydrogen sulfide by the salt marsh cordgrass Spartina alterniflora in a North Carolina salt marsh. Most of the plant sulfur derived from pore-water sulfide was recovered as sulfate, an indication that the sulfide had been oxidized within

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

    SciTech Connect

    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 ?{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.

  13. Stable water isotope simulation by current land-surface schemes: Results of iPILPS Phase 1

    E-print Network

    , we find that the empirically based Craig-Gordon parameterization (of isotopic fractionation during very different isotopic responses. We show that ILSS-simulated isotopic equilibrium is independentStable water isotope simulation by current land-surface schemes: Results of iPILPS Phase 1 A

  14. Isotopic tracing of clear water sources in an urban sewer: A combined water and dissolved sulfate stable isotope approach.

    PubMed

    Houhou, J; Lartiges, B S; France-Lanord, C; Guilmette, C; Poix, S; Mustin, C

    2010-01-01

    This paper investigates the potential of stable isotopes of both water (deltaD and deltaOH(2)O18) and dissolved sulfate (delta(34)S and deltaOSO(4)18) for determining the origin and the amount of clear waters entering an urban sewer. The dynamics of various hydrological processes that commonly occur within the sewer system such as groundwater infiltration, rainwater percolation, or stormwater release from retention basins, can be readily described using water isotope ratios. In particular, stable water isotopes indicate that the relative volumes of infiltrated groundwater and sewage remain approximately constant and independent of wastewater flow rate during the day, thus demonstrating that the usual quantification of parasitic discharge from minimal nocturnal flow measurements can lead to completely erroneous results. The isotopic signature of dissolved sulfate can also provide valuable information about the nature of water inputs to the sewage flow, but could not be used in our case to quantify the infiltrating water. Indeed, even though the microbial activity had a limited effect on the isotopic composition of dissolved sulfate at the sampling sites investigated, the dissolved sulfate concentration in sewage was regulated by the formation of barite and calcium-phosphate mineral species. Sulfate originating from urine was also detected as a source using the oxygen isotopic composition of sulfate, which suggests that deltaOSO(4)18 might find use as a urine tracer. PMID:19822346

  15. Zinc isotope ratio imaging of rat brain thin sections from stable isotope tracer studies by LA-MC-ICP-MS.

    PubMed

    Urgast, Dagmar S; Hill, Sarah; Kwun, In-Sook; Beattie, John H; Goenaga-Infante, Heidi; Feldmann, Jörg

    2012-10-01

    Zinc stable isotope tracers (??Zn and ??Zn) were injected into rats at two different time points to investigate the feasibility of using tracers to study zinc kinetics at the microscale within distinct tissue features. Laser ablation coupled to multi-collector ICP-MS was used to analyse average isotope ratios in liver thin sections and to generate bio-images showing zinc isotope ratio distribution in brain thin sections. Average isotope ratios of all samples from treated animals were found to be statistically different (P < 0.05) from samples from untreated control animals. Furthermore, differing isotope ratios in physiological features of the brain, namely hippocampus, amygdala, cortex and hypothalamus, were identified. This indicates that these regions differ in their zinc metabolism kinetics. While cortex and hypothalamus contain more tracer two days after injection than 14 days after injection, the opposite is true for hippocampus and amygdala. This study showed that stable isotope tracer experiments can be combined with laser ablation MC-ICP-MS to measure trace element kinetics in tissues at a microscale level. PMID:22907676

  16. Lake Louise Water (USGS47): A new isotopic reference water for stable hydrogen and oxygen isotope measurements

    USGS Publications Warehouse

    Qi, Haiping; Lorenz, Jennifer M.; Coplen, Tyler B.; Tarbox, Lauren V.; Mayer, Bernhard; Taylor, Steve

    2014-01-01

    RESULTS: The ?2H and ?18O values of this reference water are –150.2 ± 0.5 ‰ and –19.80 ± 0.02 ‰, respectively, relative to VSMOW on scales normalized such that the ?2H and ?18O values of SLAP reference water are, respectively, –428 and –55.5 ‰. Each uncertainty is an estimated expanded uncertainty (U = 2uc) about the reference value that provides an interval that has about a 95-percent probability of encompassing the true value. CONCLUSION: This isotopic reference material, designated as USGS47, is intended as one of two isotopic reference waters for daily normalization of stable hydrogen and stable oxygen isotopic analysis of water with a mass spectrometer or a laser absorption spectrometer. "

  17. Mercury stable isotopes in sediments and largemouth bass from Florida lakes, USA.

    PubMed

    Sherman, Laura S; Blum, Joel D

    2013-03-15

    Humans and wildlife can be exposed to mercury (Hg) through the consumption of fish with elevated concentrations of methylmercury (MeHg). Studies have shown that increased atmospheric deposition of Hg often leads to increased MeHg concentrations in aquatic organisms. However, depending on the ecosystem characteristics, reductions in Hg emissions may not always lead to immediate decreases in fish MeHg concentrations. Measurements of natural abundance Hg stable isotope ratios may enable a better understanding of these complex relationships. To gain insight into the sources of Hg to sport fish in central Florida, we measured the Hg isotopic compositions of surface sediments and largemouth bass from freshwater lakes. We found that fish collected from lakes located near the large Crystal River coal-fired power plant did not display evidence of anomalous negative ?(202)Hg values that were observed in nearby precipitation. This suggests that Hg recently deposited from the atmosphere is not preferentially methylated and bioaccumulated in these lakes relative to previously deposited Hg accumulated in the lake sediments. We also observed significant positive ?(199)Hg values in the fish that were correlated with light penetration depth in the lakes from which they were collected. This indicates that a significant amount of photochemical degradation of MeHg (up to ~40%) occurred prior to uptake of the remaining MeHg into the food webs. These results suggest that depending on physical lake characteristics and biogeochemical factors, decreased atmospheric Hg deposition may not lead to immediate short-term reductions in fish MeHg concentrations. Instead, recovery of some freshwater fish populations to baseline MeHg concentrations may take decades to centuries. PMID:23062970

  18. Late quaternary paleoceanography of the Atlantic Ocean: foraminiferal faunal and stable-isotopic evidence

    SciTech Connect

    Mix, A.C.

    1986-01-01

    The timing, frequencies, and rates of change of tropical Atlantic climates are studied on a glacial/interglacial scale, using foraminferal faunal abundance and stable isotopic data to estimate temperatures, ice volumes, and water mass properties of the surface and deep ocean. Oxygen-isotope and radiocarbon data constrain the timing of the last deglacial transition (Termination 1) to between 14,000 and 6000 yr BP. Deglaciation was not a continuous process, but may have occurred in steps from 14,000 to 12,000 yr BP, 10,000 to 8000 yr BP, and 7000 to 6000 yr BP. Changes in the ..delta../sup 18/O of glacier ice may induce a lag of the marine ..delta../sup 18/O record behind ice volume of 1000 to 3000 years. Temperature changes estimated by foraminferal transfer functions were not detected in down-core planktonic foraminferal ..delta../sup 18/O data. Hemispheric symmetry of glacial cooling may reflect linkage to high latitude climate changes via trade wind intensities and/or directions. During deglaciation, the North Atlantic was relatively cold, the South Atlantic was relatively warm, and equatorial seasonal contrast was low. This may reflect reduction of northward cross-equatorial heat transport in the ocean, and possible monsoonal effects. Climate changes also extend to the deep ocean. At mid-depths of the tropical Atlantic, minimum Atlantic-Pacific ..delta../sup 13/C difference occurring on average during deglaciation (with a strong 23,000-yr precession cycle) suggests reduced formation of a warm component of NADW during deglaciation. A deeper sites in the North Atlantic, reduced ventilation of deep basins during glacial maxima is linked to surface-water variability of the subpolar North Atlantic.

  19. Stable carbon isotope fractionation by sulfate-reducing bacteria

    NASA Technical Reports Server (NTRS)

    Londry, Kathleen L.; Des Marais, David J.

    2003-01-01

    Biogeochemical transformations occurring in the anoxic zones of stratified sedimentary microbial communities can profoundly influence the isotopic and organic signatures preserved in the fossil record. Accordingly, we have determined carbon isotope discrimination that is associated with both heterotrophic and lithotrophic growth of pure cultures of sulfate-reducing bacteria (SRB). For heterotrophic-growth experiments, substrate consumption was monitored to completion. Sealed vessels containing SRB cultures were harvested at different time intervals, and delta(13)C values were determined for gaseous CO(2), organic substrates, and products such as biomass. For three of the four SRB, carbon isotope effects between the substrates, acetate or lactate and CO(2), and the cell biomass were small, ranging from 0 to 2 per thousand. However, for Desulfotomaculum acetoxidans, the carbon incorporated into biomass was isotopically heavier than the available substrates by 8 to 9 per thousand. SRB grown lithoautotrophically consumed less than 3% of the available CO(2) and exhibited substantial discrimination (calculated as isotope fractionation factors [alpha]), as follows: for Desulfobacterium autotrophicum, alpha values ranged from 1.0100 to 1.0123; for Desulfobacter hydrogenophilus, the alpha value was 0.0138, and for Desulfotomaculum acetoxidans, the alpha value was 1.0310. Mixotrophic growth of Desulfovibrio desulfuricans on acetate and CO(2) resulted in biomass with a delta(13)C composition intermediate to that of the substrates. The extent of fractionation depended on which enzymatic pathways were used, the direction in which the pathways operated, and the growth rate, but fractionation was not dependent on the growth phase. To the extent that environmental conditions affect the availability of organic substrates (e.g., acetate) and reducing power (e.g., H(2)), ecological forces can also influence carbon isotope discrimination by SRB.

  20. Determination of Trophic Transfer at a Created Intertidal Oyster ( Crassostrea ariakensis ) Reef in the Yangtze River Estuary Using Stable Isotope Analyses

    Microsoft Academic Search

    Wei-min Quan; Austin T. Humphries; Li-yan Shi; Ya-qu Chen

    Oysters can create reefs that provide habitat for associated species resulting in elevated resident abundances, lower mortality\\u000a rates, and increased growth and survivorship compared to other estuarine habitats. However, there is a need to quantify trophic\\u000a relationships and transfer at created oyster reefs to provide a better understanding of their potential in creating suitable\\u000a nekton habitat. Stable isotope analyses (?13C

  1. Kinetic fractionation of stable nitrogen isotopes during amino acid transamination

    NASA Astrophysics Data System (ADS)

    Macko, Stephen A.; Estep, Marilyn L. Fogel; Engel, Michael H.; Hare, P. E.

    1986-10-01

    This study evaluates a kinetic isotope effect involving 15N, during the transamination reactions catalyzed by glutamic oxalacetic transaminase. During the transfer of amino nitrogen from glutamic acid to oxaloacetate to form aspartic acid, 14NH 2 reacted 1.0083 times faster than 14NH 2. In the reverse reaction transferring NH 2 from aspartic acid to ?-ketoglutarate, 14NH 2 was incorporated 1.0017 times faster than 15NH 2. Knowledge of the magnitude and sign of these isotope effects will be useful in the interpretation of the distribution of 15N in biological and geochemical systems.

  2. Stable Isotope Models Predict Foraging Habitat of Northern Fur Seals (Callorhinus ursinus) in Alaska.

    PubMed

    Zeppelin, T K; Johnson, D S; Kuhn, C E; Iverson, S J; Ream, R R

    2015-01-01

    We developed models to predict foraging habitat of adult female northern fur seals (Callorhinus ursinus) using stable carbon (?13C) and nitrogen (?15N) isotope values from plasma and red blood cells. Binomial generalized linear mixed models were developed using blood isotope samples collected from 35 adult female fur seals on three breeding colonies in Alaska during July-October 2006. Satellite location and dive data were used to define habitat use in terms of the proportion of time spent or dives made in different oceanographic/bathymetric domains. For both plasma and red blood cells, the models accurately predicted habitat use for animals that foraged exclusively off or on the continental shelf. The models did not perform as well in predicting habitat use for animals that foraged in both on- and off-shelf habitat; however, sample sizes for these animals were small. Concurrently collected scat, fatty acid, and dive data confirmed that the foraging differences predicted by isotopes were associated with diet differences. Stable isotope samples, dive data, and GPS location data collected from an additional 15 females during August-October 2008 validated the effective use of the models across years. Little within year variation in habitat use was indicated from the comparison between stable isotope values from plasma (representing 1-2 weeks) and red blood cells (representing the prior few months). Constructing predictive models using stable isotopes provides an effective means to assess habitat use at the population level, is inexpensive, and can be applied to other marine predators. PMID:26030280

  3. Stable Isotope Models Predict Foraging Habitat of Northern Fur Seals (Callorhinus ursinus) in Alaska

    PubMed Central

    Zeppelin, T. K.; Johnson, D. S.; Kuhn, C. E.; Iverson, S. J.; Ream, R. R.

    2015-01-01

    We developed models to predict foraging habitat of adult female northern fur seals (Callorhinus ursinus) using stable carbon (?13C) and nitrogen (?15N) isotope values from plasma and red blood cells. Binomial generalized linear mixed models were developed using blood isotope samples collected from 35 adult female fur seals on three breeding colonies in Alaska during July-October 2006. Satellite location and dive data were used to define habitat use in terms of the proportion of time spent or dives made in different oceanographic/bathymetric domains. For both plasma and red blood cells, the models accurately predicted habitat use for animals that foraged exclusively off or on the continental shelf. The models did not perform as well in predicting habitat use for animals that foraged in both on- and off-shelf habitat; however, sample sizes for these animals were small. Concurrently collected scat, fatty acid, and dive data confirmed that the foraging differences predicted by isotopes were associated with diet differences. Stable isotope samples, dive data, and GPS location data collected from an additional 15 females during August-October 2008 validated the effective use of the models across years. Little within year variation in habitat use was indicated from the comparison between stable isotope values from plasma (representing 1-2 weeks) and red blood cells (representing the prior few months). Constructing predictive models using stable isotopes provides an effective means to assess habitat use at the population level, is inexpensive, and can be applied to other marine predators. PMID:26030280

  4. Stable isotope variations in Late Pennsylvanian brachiopods from cyclic sedimentary deposits: paleoenvironmental and diagenetic implications

    E-print Network

    Adlis, David Scott

    1986-01-01

    with diagenetic meteoric waters can alter the original composition of the shell material, in which case the shells would not accurately reflect the original isotopic composition. Preliminary isotopic analyses of the thin brachial valve of ~gggg~ and thin... in the intervals, while the brachial valves were less commonly recovered. Other brachiopods and molluscs are common in most intervals. Echinoid plates and spines and crinoid columnals were common, and immature ammonoids were abundant in select intervals...

  5. Stable nitrogen isotope studies of the pelagic food web on the Atlantic shelf of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Bode, Antonio; Alvarez-Ossorio, M. Teresa; Cunha, M. Emilia; Garrido, Susana; Peleteiro, J. Benito; Porteiro, Carmela; Valdés, Luis; Varela, Manuel

    2007-08-01

    The structure and variability of pelagic food webs along the north and northwestern shelf of the Iberian Peninsula were analysed using natural abundance of nitrogen stable isotopes of plankton and pelagic consumers. Plankton composition was mainly studied in size-fractionated samples, but also the isotopic signatures of three copepod species, as representative of primary consumers, were considered. Several fish species were included as planktivorous consumers, with special attention to sardine ( Sardina pilchardus). Finally, top pelagic consumers were represented by the common dolphin ( Delphinus delphis). The relationship between trophic position and body size implies large variability in the ratio of predator to prey sizes, likely because widespread omnivory and plankton consumption by relatively large predators. Planktivorous species share a common trophic position, suggesting potential competition for food, and low nitrogen isotope enrichment between prey and consumers suggest nutrient limitation and recycling at the base of the food web. Both experimental and field evidences indicate that the muscle of sardine integrates fish diet over seasonal periods and reflects the composition of plankton from large shelf areas. The low mobility of sardines during periods of low population size is consistent with differential isotopic signatures found in shelf zones characterised by upwelling nutrient inputs.

  6. Production and use of stable isotope-labeled proteins for absolute quantitative proteomics.

    PubMed

    Lebert, Dorothée; Dupuis, Alain; Garin, Jérôme; Bruley, Christophe; Brun, Virginie

    2011-01-01

    In the field of analytical chemistry, stable isotope dilution assays are extensively used in combination with liquid chromatography-mass spectrometry (LC-MS) to provide confident quantification results. Over the last decade, the principle of isotope dilution has been adopted by the proteomic community in order to accurately quantify proteins in biological samples. In these experiments, a protein's concentration is deduced from the ratio between the MS signal of a tryptic peptide and that of a stable isotope-labeled analog, which serves as an internal standard. The first isotope dilution standards introduced in proteomics were chemically synthesized peptides incorporating a stable isotope-tagged amino acid. These isotopically labeled peptide standards, which are currently widely used, are generally added to samples after protein isolation and digestion. Thus, if protein enrichment is necessary, they do not allow correction for protein losses that may occur during sample pre-fractionation, nor do they allow the tryptic digestion yield to be taken into account. To reduce these limitations we have developed the PSAQ (Protein Standard Absolute Quantification) strategy using full-length stable isotope-labeled proteins as quantification standards. These standards and the target proteins share identical biochemical properties. This allows standards to be spiked into samples at an early stage of the analytical process. Thanks to this possibility, the PSAQ method provides highly accurate quantification results, including for samples requiring extensive biochemical pre-fractionation. In this chapter, we describe the production of full-length stable isotope-labeled proteins (PSAQ standards) using cell-free expression devices. The purification and quality control of protein standards, crucial for good-quality and accurate measurements, are also detailed. Finally, application of the PSAQ method to a typical protein quantification assay is presented. PMID:21604118

  7. High-sensitivity stable-isotope probing by a quantitative terminal restriction fragment length polymorphism protocol.

    PubMed

    Andeer, Peter; Strand, Stuart E; Stahl, David A

    2012-01-01

    Stable-isotope probing (SIP) has proved a valuable cultivation-independent tool for linking specific microbial populations to selected functions in various natural and engineered systems. However, application of SIP to microbial populations with relatively minor buoyant density increases, such as populations that utilize compounds as a nitrogen source, results in reduced resolution of labeled populations. We therefore developed a tandem quantitative PCR (qPCR)-TRFLP (terminal restriction fragment length polymorphism) protocol that improves resolution of detection by quantifying specific taxonomic groups in gradient fractions. This method combines well-controlled amplification with TRFLP analysis to quantify relative taxon abundance in amplicon pools of FAM-labeled PCR products, using the intercalating dye EvaGreen to monitor amplification. Method accuracy was evaluated using mixtures of cloned 16S rRNA genes, DNA extracted from low- and high-G+C bacterial isolates (Escherichia coli, Rhodococcus, Variovorax, and Microbacterium), and DNA from soil microcosms amended with known amounts of genomic DNA from bacterial isolates. Improved resolution of minor shifts in buoyant density relative to TRFLP analysis alone was confirmed using well-controlled SIP analyses. PMID:22038597

  8. Seasonal reliance on nectar by an insectivorous bat revealed by stable isotopes.

    PubMed

    Frick, Winifred F; Shipley, J Ryan; Kelly, Jeffrey F; Heady, Paul A; Kay, Kathleen M

    2014-01-01

    Many animals have seasonally plastic diets to take advantage of seasonally abundant plant resources, such as fruit or nectar. Switches from insectivorous diets that are protein rich to fruits or nectar that are carbohydrate rich present physiological challenges, but are routinely done by insectivorous songbirds during migration. In contrast, insectivorous bat species are not known to switch diets to consume fruit or nectar. Here, we use carbon stable isotope ratios to establish the first known case of a temperate bat species consuming substantial quantities of nectar during spring. We show that pallid bats (Antrozous pallidus) switch from a diet indistinguishable from that of sympatric insectivorous bat species in winter (when no cactus nectar is present) to a diet intermediate between those of insectivorous bats and nectarivorous bats during the spring bloom of a bat-adapted cactus species. Combined with previous results that established that pallid bats are effective pollinators of the cardon cactus (Pachycereus pringlei), our results suggest that the interaction between pallid bats and cardon cacti represents the first-known plant-pollinator mutualism between a plant and a temperate bat. Diet plasticity in pallid bats raises questions about the degree of physiological adaptations of insectivorous bats for incorporation of carbohydrate-rich foods, such as nectar or fruit, into the diet. PMID:24276770

  9. Lignocellulose-responsive bacteria in a southern California salt marsh identified by stable isotope probing

    PubMed Central

    Darjany, Lindsay E.; Whitcraft, Christine R.; Dillon, Jesse G.

    2014-01-01

    Carbon cycling by microbes has been recognized as the main mechanism of organic matter decomposition and export in coastal wetlands, yet very little is known about the functional diversity of specific groups of decomposers (e.g., bacteria) in salt marsh benthic trophic structure. Indeed, salt marsh sediment bacteria remain largely in a black box in terms of their diversity and functional roles within salt marsh benthic food web pathways. We used DNA stable isotope probing (SIP) utilizing 13C-labeled lignocellulose as a proxy to evaluate the fate of macrophyte-derived carbon in benthic salt marsh bacterial communities. Overall, 146 bacterial species were detected using SIP, of which only 12 lineages were shared between enriched and non-enriched communities. Abundant groups from the 13C-labeled community included Desulfosarcina, Spirochaeta, and Kangiella. This study is the first to use heavy-labeled lignocellulose to identify bacteria responsible for macrophyte carbon utilization in salt marsh sediments and will allow future studies to target specific lineages to elucidate their role in salt marsh carbon cycling and ultimately aid our understanding of the potential of salt marshes to store carbon. PMID:24917856

  10. Identification of functionally active aerobic methanotrophs in sediments from an arctic lake using stable isotope probing

    USGS Publications Warehouse

    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Catranis, Catharine; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

    2012-01-01

    Arctic lakes are a significant source of the greenhouse gas methane (CH4), but the role that methane oxidizing bacteria (methanotrophs) play in limiting the overall CH4 flux is poorly understood. Here, we used stable isotope probing (SIP) techniques to identify the metabolically active aerobic methanotrophs in upper sediments (0–1 cm) from an arctic lake in northern Alaska sampled during ice-free summer conditions. The highest CH4 oxidation potential was observed in the upper sediment (0–1 cm depth) with 1.59 ?mol g wet weight-1 day-1 compared with the deeper sediment samples (1–3 cm, 3–5 cm and 5–10 cm), which exhibited CH4 oxidation potentials below 0.4 ?mol g wet weight-1 day-1. Both type I and type II methanotrophs were directly detected in the upper sediment total communities using targeted primer sets based on 16S rRNA genes. Sequencing of 16S rRNA genes and functional genes (pmoA and mxaF) in the 13C-DNA from the upper sediment indicated that type I methanotrophs, mainly Methylobacter, Methylosoma, Methylomonas and Methylovulum miyakonense, dominated the assimilation of CH4. Methylotrophs, including the genera Methylophilus and/or Methylotenera, were also abundant in the 13CDNA. Our results show that a diverse microbial consortium acquired carbon from CH4 in the sediments of this arctic lake.

  11. DNA-based stable isotope probing enables the identification of active bacterial endophytes in potatoes.

    PubMed

    Rasche, Frank; Lueders, Tillmann; Schloter, Michael; Schaefer, Sabine; Buegger, Franz; Gattinger, Andreas; Hood-Nowotny, Rebecca C; Sessitsch, Angela

    2009-03-01

    A (13)CO2 (99 atom-%, 350 ppm) incubation experiment was performed to identify active bacterial endophytes in two cultivars of Solanum tuberosum, cultivars Desirée and Merkur. We showed that after the assimilation and photosynthetic transformation of (13)CO2 into (13)C-labeled metabolites by the plant, the most directly active, cultivar specific heterotrophic endophytic bacteria that consume these labeled metabolite scan be identified by DNA stable isotope probing (DNA-SIP).Density-resolved DNA fractions obtained from SIP were subjected to 16S rRNA gene-based community analysis using terminal restriction fragment length polymorphism analysis and sequencing of generated gene libraries.Community profiling revealed community compositions that were dominated by plant chloroplast and mitochondrial 16S rRNA genes for the 'light' fractions of (13)CO2-incubated potato cultivars and of potato cultivars not incubated with (13)CO2. In the 'heavy' fractions of the (13)CO2-incubated endophyte DNA, a bacterial 492-bp terminal restriction fragment became abundant, which could be clearly identified as Acinetobacter and Acidovorax spp. in cultivars Merkur and Desirée,respectively, indicating cultivar-dependent distinctions in (13)C-label flow. These two species represent two common potato endophytes with known plant-beneficial activities.The approach demonstrated the successful detection of active bacterial endophytes in potato. DNA-SIP therefore offers new opportunities for exploring the complex nature of plant-microbe interactions and plant-dependent microbial metabolisms within the endosphere. PMID:19140937

  12. A manual for a laboratory information management system (LIMS) for light stable isotopes

    USGS Publications Warehouse

    Coplen, Tyler B.

    1997-01-01

    The reliability and accuracy of isotopic data can be improved by utilizing database software to (i) store information about samples, (ii) store the results of mass spectrometric isotope-ratio analyses of samples, (iii) calculate analytical results using standardized algorithms stored in a database, (iv) normalize stable isotopic data to international scales using isotopic reference materials, and (v) generate multi-sheet paper templates for convenient sample loading of automated mass-spectrometer sample preparation manifolds. Such a database program is presented herein. Major benefits of this system include (i) an increase in laboratory efficiency, (ii) reduction in the use of paper, (iii) reduction in workload due to the elimination or reduction of retyping of data by laboratory personnel, and (iv) decreased errors in data reported to sample submitters. Such a database provides a complete record of when and how often laboratory reference materials have been analyzed and provides a record of what correction factors have been used through time. It provides an audit trail for stable isotope laboratories. Since the original publication of the manual for LIMS for Light Stable Isotopes, the isotopes 3 H, 3 He, and 14 C, and the chlorofluorocarbons (CFCs), CFC-11, CFC-12, and CFC-113, have been added to this program.

  13. A manual for a Laboratory Information Management System (LIMS) for light stable isotopes

    USGS Publications Warehouse

    Coplen, Tyler B.

    1998-01-01

    The reliability and accuracy of isotopic data can be improved by utilizing database software to (i) store information about samples, (ii) store the results of mass spectrometric isotope-ratio analyses of samples, (iii) calculate analytical results using standardized algorithms stored in a database, (iv) normalize stable isotopic data to international scales using isotopic reference materials, and (v) generate multi-sheet paper templates for convenient sample loading of automated mass-spectrometer sample preparation manifolds. Such a database program is presented herein. Major benefits of this system include (i) an increase in laboratory efficiency, (ii) reduction in the use of paper, (iii) reduction in workload due to the elimination or reduction of retyping of data by laboratory personnel, and (iv) decreased errors in data reported to sample submitters. Such a database provides a complete record of when and how often laboratory reference materials have been analyzed and provides a record of what correction factors have been used through time. It provides an audit trail for stable isotope laboratories. Since the original publication of the manual for LIMS for Light Stable Isotopes, the isotopes 3 H, 3 He, and 14 C, and the chlorofluorocarbons (CFCs), CFC-11, CFC-12, and CFC-113, have been added to this program.

  14. Preliminary mineralogic, fluid inclusion, and stable isotope study of the Mahd adh Dhahab gold mine, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Rye, Robert O.; Hall, W.E.; Cunningham, C.G.; Czamanske, G.K.; Afifi, A.M.; Stacey, J.S.

    1983-01-01

    The Mahd adh Dhahab mine, located about 280 km northeast of Jiddah, Kingdom of Saudi Arabia, has yielded more than 2 million ounces of gold from periodic production during the past 3,000 years. A new orebody on the southern side of the ancient workings, known as the South orebody, is being developed by Gold Fields-Mahd adh Dhahab Limited. A suite of samples was collected from the newly exposed orebody for preliminary mineralogic, stable isotope, fluid inclusion, and geochemical studies. The Mahd adh Dhahab deposit is in the carapace of a Proterozoic epizonal rhyolite stock that domed pyroclastic and metasedimentary rocks of the Proterozoic Halaban group. Ore of gold, silver, copper, zinc, tellurium, and lead is associated with north-trending, steeply dipping quartz veins in a zone 1,000 m long and 400 m wide. The veins include an assemblage of quartz-chlorite-pyrite-hematite-chalcopyrite-sphalerite-precious metals, which is similar to the mineral assemblage at the epithermal deposit at Creede, Colorado. The primary ore contains abundant chalcopyrite, sphalerite, and pyrite in addition to a complex precious metal assemblage. Gold and silver occur principally as minute grains of telluride minerals disseminated in quartz-chlorite-hematite and as inclusions in chalcopyrite and sphalerite. Telluride minerals include petzite, hessite, and sylvanite. Free gold is present but not abundant. All of the vein-quartz samples contained abundant, minute inclusions of both low-density, vapor-rich fluids and liquid-rich fluids. Primary fluid inclusions yielded homogenization temperatures of from 110? to 238? C. Preliminary light-stable isotope studies of the sulfide minerals and quartz showed that all of the d34S values are between 1.2 and 6.3 per mil, which is a typical range for hydrothermal sulfide minerals that derive their sulfur from an igneous source. The data-suggest that the sulfide sulfur isotope geochemistry was controlled by exchange with la large sulfur isotope reservoir at depth. The d18O values of all stages of vein quartz in the South orebody range between 8.5 and 11.1 per mil. This range is similar to that for quartz from the North orebody and indicates that the hydrothermal system consisted of dominantly exchanged meteoric water, which was uniform in temperature and d18O content throughout the area during the entire period of mineralization. Lead isotope analyses of two galena samples indicate that the lead in the South orebody is less radiogenic than that from the North orebody and confirm that the lead was derived from oceanic crust approximately 700 Ma ago.

  15. Diurnal changes in stable isotopes of leaf water on the southern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yu, Wusheng

    2015-04-01

    Leaf water in plants playing a significant role in the hydrological cycle, will change the existing stable isotope hydrological cycle pattern. Based on stable isotopic analysis and corresponding meteorological measurement, a better understanding of water transport, storage, and usage can be achieved in stable isotope hydrological cycle on the Tibetan Plateau. This study focuses on the diurnal variations of leaf water stable isotopes at the Lhasa station, southern Tibetan Plateau. The results of our data show that, the diurnal variations of stable isotopic compositions (?18O and ?D) of leaf water fluctuate obviously, with high value in the daytime and low value at night. The diurnal fluctuations of deuterium excess (d) of leaf water are also clear, with low value in the daytime and high value at night. At diurnal time scale, both air temperature and relative humidity control the variations of ?18O and ?D in leaf water. Relative humidity correlates negatively with ?18O, and positively with d, in contrast to air temperature. The results reveal that deuterium excess may be an indicator of plant transpiration.

  16. Monitoring of the aerobe biodegradation of chlorinated organic solvents by stable isotope analysis

    NASA Astrophysics Data System (ADS)

    Horváth, Anikó; Futó, István; Palcsu, László

    2014-05-01

    Our chemical-biological basic research aims to eliminate chlorinated environmental contaminants from aquifers around industrial areas in the frame of research program supported by the European Social Fund (TÁMOP-4.2.2.A-11/1/KONV-2012-0043). The most careful and simplest way includes the in situ biodegradation with the help of cultured and compound specific strains. Numerous members of Pseudomonas bacteria are famous about function of bioremediation. They can metabolism the environmental hazardous chemicals like gas oils, dyes, and organic solvents. Our research based on the Pseudomonas putida F1 strain, because its ability to degrade halogenated hydrocarbons such as trichloroethylene. Several methods were investigated to estimate the rate of biodegradation, such as the measurement of the concentration of the pollutant along the contamination pathway, the microcosm's studies or the compound specific stable isotope analysis. In this area in the Transcarpathian basin we are pioneers in the stable isotope monitoring of biodegradation. The main goal is to find stable isotope fractionation factors by stable isotope analysis, which can help us to estimate the rate and effectiveness of the biodegradation. The subsequent research period includes the investigation of the method, testing its feasibility and adaptation in the environment. Last but not least, the research gives an opportunity to identify the producer of the contaminant based on the stable isotope composition of the contaminant.

  17. Tracking Diet Preferences of Bats Using Stable Isotope and Fatty Acid Signatures of Faeces

    PubMed Central

    Lam, Monika My-Y; Martin-Creuzburg, Dominik; Rothhaupt, Karl-Otto; Safi, Kamran; Yohannes, Elizabeth; Salvarina, Ioanna

    2013-01-01

    Stable isotope and fatty acid signatures of biomaterials can provide important information about the dietary niche of animals. Stable isotope and fatty acid signatures differ between aquatic and terrestrial food webs, and therefore can be used to assess the aquatic and terrestrial contributions to the diets of species. We studied faecal samples of three co-occurring bat species with known differences in feeding preferences. The aim was to assess whether stable isotope and fatty acid signatures of faeces can be used to determine feeding preferences. We used bat faeces because they can be easily and non-invasively collected. We hypothesised that faeces stable isotope and fatty acid signatures will reveal the terrestrial, aquatic and mixed feeding niches of Myotis myotis, M. daubentonii, and M. mystacinus, respectively. As predicted, the faeces of M. myotis were characterized by higher ?13C values and higher concentrations of linoleic acid and total ?6 polyunsaturated fatty acids (PUFAs), which are typically higher in terrestrial food webs. The faeces of M. daubentonii had higher ?15? values and higher concentrations of docosahexaenoic acid and total ?3 PUFAs, characteristic features of aquatic systems. Myotis mystacinus faeces had intermediate ?15? values and concentrations of both types of fatty acids. Our results show that analysing stable isotope and/or fatty acid signatures of faeces provides a promising, non-invasive tool to study the feeding ecology of bats and to assess aquatic-terrestrial interactions. PMID:24376703

  18. Stable carbon isotope fractionation by acetotrophic sulfur-reducing bacteria.

    PubMed

    Goevert, Dennis; Conrad, Ralf

    2010-02-01

    Acetate is the most important intermediate in anaerobic degradation of organic matter. The carbon isotope effects associated with the oxidation of acetate (epsilon(ac)) were examined for four acetotrophic sulfur reducers, Desulfuromonas acetoxidans, Desulfuromonas thiophila, Desulfurella acetivorans, and Hippea maritima. During the consumption of acetate and sulfur, acetate was enriched in (13)C by 11.5 and 11.2 per thousand in Desulfuromonas acetoxidans and Desulfuromonas thiophila, respectively. By contrast, isotope fractionation in D. acetivorans and H. maritima resulted in isotope enrichment factors of epsilon(ac)=-6.3 per thousand and -8.4 per thousand, respectively. These sulfur-reducing bacteria all metabolize acetate via the tricarboxylic acid cycle, but have different mechanisms for the initial activation of acetate. In Desulfuromonas acetoxidans, acetyl-CoA is formed by succinyl-CoA : acetate-CoA-transferase, and in D. acetivorans by acetate kinase and phosphate acetyltransferase. Hence, values of epsilon(ac) seem to be characteristic for the type of activation of acetate to acetyl-CoA in acetotrophic sulfur reducers. Summarizing epsilon(ac)-values in anaerobic acetotrophic microorganisms, it appears that isotope fractionation depends on the mechanism of acetate activation to acetyl-CoA, on the key enzyme of the acetate dissimilation pathway, and on the bioavailability of acetate, which all have to be considered when using delta(13)C of acetate in environmental samples for diagnosis of the involved microbial populations. PMID:20002180

  19. Origins of etioporphyrins in sediments - Evidence from stable carbon isotopes

    NASA Technical Reports Server (NTRS)

    Boreham, Christopher J.; Fookes, Christopher J. R.; Popp, Brian N.; Hayes, J. M.

    1989-01-01

    In samples of the Julia Creek and Condor oil shales (Australia, Albian, and early Tertiary, respectively) etioporphyrin III is significantly depleted in C-13 (4 per mil) relative to porphyrins derived from chlorophylls. This isotopic difference suggests a large contribution from some independent source. The haem group found in cytochromes derived from microbial sources is the most likely candidate.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  1. Using chromium stable isotope ratios to quantify Cr(VI) reduction: Lack of sorption effects

    USGS Publications Warehouse

    Ellis, A.S.; Johnson, T.M.; Bullen, T.D.

    2004-01-01

    Chromium stable isotope values can be effectively used to monitor reduction of Cr(VI) in natural waters. We investigate effects of sorption during transport of Cr(VI) which may also shift Cr isotopes values, complicating efforts to quantify reduction. This study shows that Cr stable isotope fractionation caused by sorption is negligible. Equilibrium fractionation of Cr stable isotopes between dissolved Cr-(VI) and Cr(VI) adsorbed onto ??-Al2O3 and goethite is less than 0.04???. (53Cr/52Cr) under environmentally relevant pH conditions. Batch experiments at pH 4.0 and pH 6.0 were conducted in series to sequentially magnify small isotope fractionations. A simple transport model suggests that adsorption may cause amplification of a small isotope fractionation along extreme fringes of a plume, leading to shifts in 53Cr/52Cr values. We therefore suggest that isotope values at extreme fringes of Cr plumes be critically evaluated for sorption effects. A kinetic effect was observed in experiments with goethite at pH 4 where apparently lighter isotopes diffuse into goethite clumps at a faster rate before eventually reaching equilibrium. This observed kinetic effect may be important in a natural system that has not attained equilibrium and is in need of further study. Cr isotope fractionation caused by speciation of Cr(VI) between HCrO4- and CrO42- was also examined, and we conclude that it is not measurable. In the absence of isotope fractionation caused by equilibrium speciation and sorption, most of the variation in ??53 Cr values may be attributed to reduction, and reliable estimates of Cr reduction can be made.

  2. Using chromium stable isotope ratios to quantify Cr(VI) reduction: lack of sorption effects.

    PubMed

    Ellis, Andre S; Johnson, Thomas M; Bullen, Thomas D

    2004-07-01

    Chromium stable isotope values can be effectively used to monitor reduction of Cr(VI) in natural waters. We investigate effects of sorption during transport of Cr(VI) which may also shift Cr isotopes values, complicating efforts to quantify reduction. This study shows that Cr stable isotope fractionation caused by sorption is negligible. Equilibrium fractionation of Cr stable isotopes between dissolved Cr(VI) and Cr(VI) adsorbed onto gamma-Al2O3 and goethite is less than 0.04 per thousand (53Cr/52Cr) under environmentally relevant pH conditions. Batch experiments at pH 4.0 and pH 6.0 were conducted in series to sequentially magnify small isotope fractionations. A simple transport model suggests that adsorption may cause amplification of a small isotope fractionation along extreme fringes of a plume, leading to shifts in 53Cr/52Cr values. We therefore suggest that isotope values at extreme fringes of Cr plumes be critically evaluated for sorption effects. A kinetic effect was observed in experiments with goethite at pH 4 where apparently lighter isotopes diffuse into goethite clumps at a faster rate before eventually reaching equilibrium. This observed kinetic effect may be important in a natural system that has not attained equilibrium and is in need of further study. Cr isotope fractionation caused by speciation of Cr(VI) between HCrO4- and CrO4(2-) was also examined, and we conclude that it is not measurable. In the absence of isotope fractionation caused by equilibrium speciation and sorption, most of the variation in delta53Cr values may be attributed to reduction, and reliable estimates of Cr reduction can be made. PMID:15296311

  3. Technical Note: Silica stable isotopes and silicification in a carnivorous sponge Asbestopluma sp.

    NASA Astrophysics Data System (ADS)

    Hendry, K. R.; Swann, G. E. A.; Leng, M. J.; Sloane, H. J.; Goodwin, C.; Berman, J.; Maldonado, M.

    2014-12-01

    The stable isotope composition of benthic sponge spicule silica is a potential source of palaeoceanographic information about past deep seawater chemistry. The silicon isotopic composition of spicules has been shown to relate to the silicic acid concentration of ambient water, although existing calibrations do exhibit a degree of scatter in the relationship. Less is known about how the oxygen isotope composition of sponge spicule silica relates to environmental conditions during growth. Here, we investigate the biological vital effects on silica silicon and oxygen isotope composition in a carnivorous sponge, Asbestopluma sp., from the Southern Ocean. We find significant variations in silicon and oxygen isotopic composition within the specimen that appear related to unusual spicule silicification. The largest variation in both isotope systems was associated to the differential distribution of an unconventional, hypersilicified spicule type (desma) along the sponge body. The absence of an internal canal in the desmas suggests an unconventional silicification pattern leading to an unusually heavy isotopic signature. Additional internal variability derives from a systematic offset between the peripheral skeleton of the body having systematically a higher isotopic composition than the internal skeleton. A simplified silicon isotope fractionation model, in which desmas were excluded, suggests that the lack of a system for seawater pumping in carnivorous sponges favours a low replenishment of dissolved silicon within the internal tissues, causing kinetic fractionation during silicification that impacts the isotopic signature of the internal skeleton. Analysis of multiple spicules should be carried out to "average out" any artefacts in order to produce more robust downcore measurements.

  4. Technical Note: Silica stable isotopes and silicification in a carnivorous sponge Asbestopluma sp.

    NASA Astrophysics Data System (ADS)

    Hendry, K. R.; Swann, G. E. A.; Leng, M. J.; Sloane, H. J.; Goodwin, C.; Berman, J.; Maldonado, M.

    2015-06-01

    The stable isotope composition of benthic sponge spicule silica is a potential source of palaeoceanographic information about past deep seawater chemistry. The silicon isotope composition of spicules has been shown to relate to the silicic acid concentration of ambient water, although existing calibrations do exhibit a degree of scatter in the relationship. Less is known about how the oxygen isotope composition of sponge spicule silica relates to environmental conditions during growth. Here, we investigate the vital effects on silica, silicon and oxygen isotope composition in a carnivorous sponge, Asbestopluma sp., from the Southern Ocean. We find significant variations in silicon and oxygen isotopic composition within the specimen that are related to unusual spicule silicification. The largest variation in both isotope systems was associated with the differential distribution of an unconventional, hypersilicified spicule type (desma) along the sponge body. The absence an internal canal in the desmas suggests an unconventional silicification pattern leading to an unusually heavy isotope signature. Additional internal variability derives from a systematic offset between the peripheral skeleton of the body having systematically a higher isotopic composition than the internal skeleton. A simplified silicon isotope fractionation model, in which desmas were excluded, suggests that the lack of a system for seawater pumping in carnivorous sponges favours a low replenishment of dissolved silicon within the internal tissues, causing kinetic fractionation during silicification that impacts the isotope signature of the internal skeleton. Analysis of multiple spicules should be carried out to "average out" any artefacts in order to produce more robust downcore measurements.

  5. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry.

    PubMed

    Coplen, Tyler B; Qi, Haiping

    2010-09-15

    An anomalous stable hydrogen isotopic fractionation of 4 ‰ in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN(2)) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) ?(2)H reproducibility (1? standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1 ‰ to 0.58 ‰. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN(2) is used as a moisture trap for gaseous hydrogen. PMID:20718408

  6. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry

    USGS Publications Warehouse

    Coplen, Tyler B.; Qi, Haiping

    2010-01-01

    An anomalous stable hydrogen isotopic fractionation of 4 ‰ in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) ?2H reproducibility (1& sigma; standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1‰ to 0.58 ‰. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen

  7. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry

    USGS Publications Warehouse

    Coplen, T.B.; Qi, H.

    2010-01-01

    An anomalous stable hydrogen isotopic fractionation of 4 ??? in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) ??2H reproducibility (1?? standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1 ??? to 0.58 ???. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen. ?? This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society.

  8. Environmental Reconstruction of the Arctic middle Eocene using Stable Isotope Analyses of Terrestrial Substrates

    NASA Astrophysics Data System (ADS)

    Jahren, A.

    2006-05-01

    I report on reconstructions of key environmental attributes of the Arctic middle Eocene (circa 45 Ma) using stable isotope analyses of terrestrial substrates from Axel Heiberg Island. The field site, now located in the far north of Canada, was home to extensive forests of deciduous conifers living at approximately 83 degrees North latitude during the middle Eocene. Fossils of these trees and associated soils are known for their spectacular preservation. Here I describe my vision of the middle Eocene Arctic environment, including the lack of polar ice, the high relative humidity, high levels of soil methane production, site temperature, and patterns of seasonality. These estimates were generated from stable isotope studies of oxygen and hydrogen in fossil cellulose, carbon and oxygen in paleosol carbonate and hydrogen within lipid biomarkers. I also report on our recent advances in the understanding of the oxygen isotopic exchange specific to position within the cellulose molecule, and its implications for the interpretation of isotopic analyses of cellulose.

  9. Climatic controls on winter water vapour stable isotopes at Lhasa, southern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Gao, Jing; Yao, Tandong; Steen-Larsen, Hans Christian; Masson-Delmotte, Valerie

    2015-04-01

    Water stable isotopes from Tibetan ice cores provide important climate information. However, the archived climate signal is an integrated signal of precipitation processes and post-deposition processes. Only very limited datasets of direct Tibetan precipitation and snowfall measurements are available so far. The isotopic composition of atmospheric water vapour traces directly the key physical processes of hydrological cycle, providing the potential of enhancing our knowledge of the climatic explanation from Tibetan ice cores. Thus, Continuous, in situ measurements of water vapour stable isotopes have been conducted at Lhasa, southern Tibetan Plateau, since October 2014, using an integrated cavity output spectroscopy analyser (LGR analyser) and a LGR water isotope standard source (WVISS) to calibrate and drift-correct the outputs. Combined with local meteorological data, TES data and simulations from the LMDZiso model, the climate controls of water vapour at Lhasa are explored at daily scale.

  10. Food web dynamics in the Scotia Sea in summer: A stable isotope study

    NASA Astrophysics Data System (ADS)

    Stowasser, G.; Atkinson, A.; McGill, R. A. R.; Phillips, R. A.; Collins, M. A.; Pond, D. W.

    2012-01-01

    The pelagic food web of the Scotia Sea was studied by analysing natural abundances of nitrogen and carbon stable isotopes of primary producers and pelagic consumers, sampled from the seasonal ice edge in the south to the Antarctic Polar Front in the north. The analysis covered, within a single mid-summer period, particulate organic matter (POM) and 38 taxa, ranging from suspension feeding copepods and salps to omnivorous euphausiids, pelagic fish and higher, land-based predators including fur seals, penguins and flying birds. Spatial variation in ? 15N of POM correlated well with nutrient availability and primary productivity. Latitudinal differences in ? 13C of POM were closely linked to variations in temperature, nutrients and productivity depending on the frontal region sampled. This translated to equivalent (although smaller) regional ? 13C differences among higher trophic levels. The trophic positions of species based on isotope values broadly agreed with previously published dietary data with three important exceptions. First, the carnivorous amphipod Themisto gaudichaudii had anomalously low ? 15N values. Second, Euphausia superba had ? 15N values that were also surprisingly low, considering the abundant literature suggesting its omnivory. Third, the copepod Rhincalanus gigas, considered a suspension feeder, had unexpectedly high ? 15N values rather more in keeping with omnivorous feeding. The consumer ? 15N values ranged from 1.2‰ (min.) measured in Salpa thompsoni (designated here as trophic level (TL) 2 across all regions) to 15.2‰ (max.) measured in white-chinned petrels ( Procellaria aequinoctialis, calculated as TL5 relative to the TL2 of salps). Excluding seabirds, the resulting food chain length of 3.7 TL (above POM at TL1) was lower than in most other Southern Ocean and temperate marine pelagic ecosystems. The majority (60%) of vertebrate predators occupied only 1-1.5 trophic levels above the herbivorous suspension feeders such as krill. This indicates the existence of the classic short food chain of POM-suspension feeder-vertebrate predator. However the presence of trophic levels 4 and above indicates the existence of alternative trophic pathways, for example involving myctophid fish or carrion, and that some wide-ranging predators which breed at South Georgia also feed outside the region. This conclusion is supported first by the continuum of ? 15N values between krill, suspension feeding copepods and myctophid fish, and secondly by higher trophic levels in several of the myctophid species in the low-krill region of the northern Scotia Sea, suggesting latitudinal differences in food web structure and food chain length.

  11. Stable isotope-labeling studies in metabolomics: new insights into structure and dynamics of metabolic networks

    PubMed Central

    Chokkathukalam, Achuthanunni; Kim, Dong-Hyun; Barrett, Michael P; Breitling, Rainer; Creek, Darren J

    2014-01-01

    The rapid emergence of metabolomics has enabled system-wide measurements of metabolites in various organisms. However, advances in the mechanistic understanding of metabolic networks remain limited, as most metabolomics studies cannot routinely provide accurate metabolite identification, absolute quantification and flux measurement. Stable isotope labeling offers opportunities to overcome these limitations. Here we describe some current approaches to stable isotope-labeled metabolomics and provide examples of the significant impact that these studies have had on our understanding of cellular metabolism. Furthermore, we discuss recently developed software solutions for the analysis of stable isotope-labeled metabolomics data and propose the bioinformatics solutions that will pave the way for the broader application and optimal interpretation of system-scale labeling studies in metabolomics. PMID:24568354

  12. The effect of different cooking processes on stable C, N, and H isotopic compositions of beef.

    PubMed

    Zhou, Jiuqing; Guo, Boli; Wei, Yimin; Zhang, Guoquan; Wei, Shuai; Ma, Yiyan

    2015-09-01

    The variability in the stable C, N, and H isotopic composition caused by different beef processing operations (boiling, frying, and roasting) was studied. The aim was to evaluate the stability of stable isotopic fingerprint information during the beef cooking process. The ?(13)C, ?(15)N, and ?(2)H values for raw, boiled, fried and roasted beef were measured, and the differences in the stable isotopic composition between raw and processed beef products were assessed. The results indicated that the ?(13)C and ?(15)N values in raw beef were not significantly different compared with processed beef, but the ?(2)H values were significantly higher in processed beef than in raw beef. In general, boiling, frying, and roasting had no significant effect on ?(13)C and ?(15)N values, but the ?(2)H value of processed beef increased. PMID:25842303

  13. Relationships between stable isotopes and metal contaminants in feathers are spurious and biologically uninformative.

    PubMed

    Bond, Alexander L

    2010-05-01

    Stable isotopes of carbon (delta(13)C) and nitrogen (delta(15)N) are used frequently in ecotoxicological investigations of birds to relate contaminant levels to trophic position (delta(15)N) or foraging location (delta(13)C) and many researchers using avian feathers in such investigations use delta(13)C or delta(15)N as a predictor of contaminant concentrations. Contaminants, especially mercury, however, are integrated into feathers over different time periods than are stable isotopes, resulting in spurious relationships that have no biological meaning. I show the fundamental principles behind the conclusion that relating delta(13)C or delta(15)N to contaminant concentrations in feathers is not appropriate in light of the number of recent studies that have employed this approach, and make recommendations for those wishing to investigate the relationship between contaminants and stable isotope ratios. PMID:20116152

  14. Neutrino scattering off the stable even-even Mo isotopes

    SciTech Connect

    Balasi, K. G.; Kosmas, T. S.; Divari, P. C. [Theoretical Physics Section, University of Ioannina, GR 45110 Ioannina (Greece)

    2009-11-09

    Inelastic neutrino-nucleus reaction cross sections are studied focusing on the neutral current processes. Particularly, we investigate the angular and initial neutrino-energy dependence of the differential and integrated cross sections for low and intermediate energies of the incoming neutrino. The nuclear wave functions for the initial and final nuclear states are constructed in the context of the quasi-particle random phase approximation (QRPA) tested on the reproducibility of the low-lying energy spectrum. The results presented here refer to the isotopes Mo{sup 92}, Mo{sup 94}, Mo{sup 96}, Mo{sup 98} and Mo{sup 100}. These isotopes could play a significant role in supernova neutrino detection in addition to their use in double-beta and neutrinoless double-beta decay experiments (e.g. MOON, NEMO III)

  15. Isotopic abundance ratios for carbon and nitrogen in Nova Herculis 1934

    NASA Technical Reports Server (NTRS)

    Sneden, C.; Lambert, D. L.

    1975-01-01

    Spectra of Nova Herculis 1934 taken during an episode of intense CN absorption are analyzed to determine the isotopic abundance ratios of C12/C13 and N14/N15. Synthetic spectrum analysis, based on the wavelengths, excitation potentials, and oscillator strengths for the CN lines, and radial velocity measurements indicate that C(12)N(14) was the dominant species in the Nova, and that the minimum abundance limit for C12/C13 is about 1.5, while the minimum for N14/N15 is about 2. The results are compared with predictions based on models of thermonuclear runaways in hydrogen-rich envelopes of white dwarfs. It is noted that the nova material may have been contaminated with C13-rich material prior to or during the eruption. Possible causes of this isotope enrichment are presented.

  16. Determination of stable carbon and hydrogen isotopes of light hydrocarbons

    Microsoft Academic Search

    Ingolf. Dumke; Eckhard. Faber; Juergen. Poggenburg

    1989-01-01

    A combined system for the measurement of ¹³C\\/¹²C and D\\/H ratios on light hydrocarbons (Câ-Câ) and COâ is described. The system is designed for natural gas and sediment gas analyses. It comprises gas chromatographic separation with online combustion of hydrocarbons to COâ and HâO, reduction of HâO to Hâ on zinc in closed ampules, and mass spectrometric determination of isotope

  17. Study of the charge radii of the stable lead isotopes

    SciTech Connect

    Borchert, G.L.; Schult, O.W.B.; Speth, J.; Hansen, P.G.; Jonson, B.; Ravn, H.; McGrory, J.B.

    1982-01-01

    Isotope shifts have been measured of the K/sub ..cap alpha..l/ x-ray lines emitted after photo ionization of /sup 204/Pb, /sup 206/Pb, /sup 207/Pb and /sup 208/Pb samples. The results are compared with theoretical values for delta < r/sup 2/> calculated with a microscopic model. The x-ray shift data are also compared with optical data and the nuclear parameters lambda derived from electron scattering results.

  18. Carbon cycle for Lake Washington - a stable isotope study

    Microsoft Academic Search

    P. D. Quay; S. R. Emerson; B. M. Quay; A. H. Devol

    1986-01-01

    The authors investigate the carbon cycle in Lake Washington for the year 1980 using monthly measurements of the dissolved inorganic carbon (DIC) and its ¹³C:¹²C isotopic composition. Mass balances of DIC and its ¹³C:¹²C yield estimates of COâ gas exchange rates and net organic carbon production rates. Between 24 June and 13 August, the calculated COâ gas invasion rate of

  19. Effects of acid washing on stable isotope ratios of C and N in penaeid shrimp and seagrass: Implications for food-web studies using multiple stable isotopes

    Microsoft Academic Search

    S. E. Bunn; M. A. Kempster; N. R. Loneragan

    1995-01-01

    We investigated the effects of acid washing on the carbon and nitrogen composition and stable isotope ratios of C and N in shrimp (Metapenaeus spp.) and seagrass (Enhalus acoroides). Acid washing did not affect the mean δ¹³C ratios for juvenile Metapenaeus moyebi and resulted in only an ecologically insignificant change (0.3%) in mean δ¹³C ratios for larger metapenaeus bennettae. In

  20. Vital effect on stable-isotope composition seen in foraminifera and coral skeletons

    Microsoft Academic Search

    Jonathan Erez

    1978-01-01

    Stable-isotope composition of carbonate precipitated by hermatypic corals and associated benthonic foraminifera is strongly influenced by photosynthesis of symbiotic algae. In situ 14C and 45Ca uptake experiments show that when photosynthesis increases, more light metabolic CO2 is incorporated in the skeleton. This mechanism explains the non-equilibrium isotopic compositions previously reported for these organisms (as well as for planktonic foraminifera), and

  1. Using stable isotopes to assess seasonal patterns of avian predation across a terrestrial-marine landscape

    Microsoft Academic Search

    Elaine K. Harding; Emiko Stevens

    2001-01-01

    In this study, we used the stable isotope ratios 15N\\/14N and 13C\\/12C to clarify the spatial and temporal patterns of small mammal derpredation by wide-ranging raptors across a salt marsh and grassland landscape. To determine whether clear isotope signals existed for the two adjoining habitats, and if these differences could allow for an assessment of the seasonal habitat origins of

  2. Mercury methylation in estuaries: Insights from using measuring rates using stable mercury isotopes

    Microsoft Academic Search

    Andrew Heyes; Robert P. Mason; Eun-Hee Kim; Elsie Sunderland

    2006-01-01

    Rates of mercury (Hg) methylation and methylmercury (MeHg) demethylation in sediment of the Hudson River, Chesapeake Bay and Bay of Fundy were measured using stable isotopes of mercury (Hg) and methylmercury (MeHg). Methylation of the isotope correlated well with in situ MeHg concentration, and MeHg turnover times were on the order of days. It was concluded that methylation was more

  3. A new automated setup for stable isotope analysis of dissolved organic carbon

    Microsoft Academic Search

    Steven Bouillon; Michael Korntheuer; Willy Baeyens; Frank Dehairs

    The measurement of stable isotope ratios on dissolved organic carbon (DOC) has long posed analytical prob- lems and limited the use of this powerful tracer in biogeochemical studies in aquatic systems. Here, we provide a detailed description of a successful coupling of a custom-modified total organic carbon analyzer (Thermo HiPerTOC) to an isotope-ratio mass spectrometer (IRMS). The method is based

  4. Fractionation of stable carbon isotopes by phosphoenopyruvate carboxylase from C4 plants 

    E-print Network

    Reibach, Paul Howard

    1976-01-01

    need to be considered, in order to determine the resultant fractionation. Clearly the active species of C02 used is important, and must be considered first in determining the amount of isotope fractionation by C plants. Determinations of the active...FRACTIONATION OP STABLE CARBON ISOTOPES BY PHOSPHOENOLPYRUYATE CARBOXYLASE FROM C& PLANTS A Thesis by PAUL HOWARD REIBACH Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree...

  5. Stable carbon isotope ratios of fatty acids in seagrass and redhead ducks

    Microsoft Academic Search

    Beth Trust Hammer; Marilyn L. Fogel; Thomas C. Hoering

    1998-01-01

    Fatty acids were extracted from roots and rhizomes of the seagrass, Halodule wrightii, and from subcutaneous fat tissues of eight redhead ducks (Aythya americana) collected either in Texas or South Dakota. Stable carbon isotope ratios (?13C) of individual fatty acids were measured by gas chromatography\\/combustion\\/isotope ratio mass spectrometry (GC\\/C\\/IRMS). In cases where individual fatty acids were not completely resolved by

  6. Stable N-isotope signatures of central European ants – assessing positions in a trophic gradient

    Microsoft Academic Search

    K. Fiedler; F. Kuhlmann; B. C. Schlick-Steiner; F. M. Steiner; G. Gebauer

    2007-01-01

    .  Studies employing stable isotope technology have greatly contributed to understanding trophic relationships of tropical ants,\\u000a but temperate-zone ants remain under-explored. We studied ?15N values of 43 ant species from three subfamilies sampled across central Europe. After statistically accounting for the effects\\u000a of elevation and geographical location of habitats, which alter the isotopic composition of nitrogen in ecosystems, significant\\u000a patterns in

  7. Individual specimen stable isotope analysis of planktonic foraminifera

    NASA Astrophysics Data System (ADS)

    Metcalfe, Brett; Feldmeijer, Wouter; Peeters, Frank; Ganssen, Gerald

    2015-04-01

    The basis of palaeoceanographic reconstructions, either as a temperature or stratigraphic tool, is the isotopic analysis (?18O; ?13C) of a group of specimens of Planktonic foraminifera collected from sediments. Repetition of such analysis is expected to reduce the variability seen compared to the variability one obtains from the analysis of individual specimens, the pooling of a large number of specimens is expected to decrease this variability with the reciprocal value of the square root of the number of specimens within a single analysis. In other words, noise is reduced but the inherent variability is lost. The isotopic information stored within a single foraminifer provides not only insight into the short term variability of the ocean but also sediment dynamics where individuals collected together in a single sedimentary sample may have calcified in different seasons (or years), at different depths, or even in different water masses. We present an overview of the individual isotope analysis conducted on a number of plankton tows, sediment traps and core tops.

  8. Reconstructing the recent methane atmospheric budget using firn air methane stable isotope analyses

    NASA Astrophysics Data System (ADS)

    Sapart, Célia Julia; Martinerie, Patricia; Witrant, Emmanuel; Monteil, Guillaume; Banda, Narcisa; Houweling, Sander; Krol, Maarten; Chappellaz, Jerome; van de Wal, Roderik; Sperlich, Peter; van der Veen, Carina; Sturges, Bill; Blunier, Thomas; Schwander, Jakob; Etheridge, David; Röckmann, Thomas

    2015-04-01

    Methane is a strong greenhouse gas and large uncertainties exist concerning the future evolution of its atmospheric abundance. Analyzing methane mixing and stable isotope ratios in air trapped in polar ice sheets helps in reconstructing the evolution of its sources and sinks in the past. This is important to improve predictions of atmospheric CH4 mixing ratios in the future under the influence of a changing climate. We present an attempt to reconcile methane stable isotopes ?13C(CH4) and ?D(CH4) records from 11 (for ?13C(CH4)) and 5 (for ?D(CH4)) boreholes in firn from both Greenland and Antarctica to reconstruct a consistent methane atmospheric history over the last 50 years. In the firn, the atmospheric signal is altered mainly by diffusion and gravitation. These processes are taken into account by firn air transport models. We show that for ?13C(CH4) the atmospheric signal is of the same order of magnitude as the firn fractionation which, together with other uncertainties such as inter-calibration problems, complicates the reconstruction of a consistent ?13C(CH4) history from multi-site firn air data. For ?D(CH4), the atmospheric signal is about 10 times larger than firn fractionation, therefore the reconstruction is much less sensitive to firn processes. This large signal allows a very consistent reconstruction from firn air from both Antarctica and Arctic firn air data. The ?D(CH4) firn air scenarios from both poles are used as input in an atmospheric inverse model to calculate the contribution of the different sources and sinks responsible for the atmospheric changes in methane observed for the past decades. Our preliminary results show that the ?D(CH4) signature of the global methane source became more enriched from 1950 to the mid-1980's and started to decrease later on and we show that it is likely caused by changes in enriched sources such as: fossil or combustion sources.

  9. Existing and emerging technologies for measuring stable isotope labelled retinol in biological samples: isotope dilution analysis of body retinol stores.

    PubMed

    Preston, Tom

    2014-01-01

    This paper discusses some of the recent improvements in instrumentation used for stable isotope tracer measurements in the context of measuring retinol stores, in vivo. Tracer costs, together with concerns that larger tracer doses may perturb the parameter under study, demand that ever more sensitive mass spectrometric techniques are developed. GCMS is the most widely used technique. It has high sensitivity in terms of sample amount and uses high resolution GC, yet its ability to detect low isotope ratios is limited by background noise. LCMSMS may become more accessible for tracer studies. Its ability to measure low level stable isotope tracers may prove superior to GCMS, but it is isotope ratio MS (IRMS) that has been designed specifically for low level stable isotope analysis through accurate analysis of tracer:tracee ratios (the tracee being the unlabelled species). Compound-specific isotope analysis, where GC is interfaced to IRMS, is gaining popularity. Here, individual 13C-labelled compounds are separated by GC, combusted to CO2 and transferred on-line for ratiometric analysis by IRMS at the ppm level. However, commercially-available 13C-labelled retinol tracers are 2 - 4 times more expensive than deuterated tracers. For 2H-labelled compounds, GC-pyrolysis-IRMS has now become more generally available as an operating mode on the same IRMS instrument. Here, individual compounds are separated by GC and pyrolysed to H2 at high temperature for analysis by IRMS. It is predicted that GC-pyrolysis-IRMS will facilitate low level tracer procedures to measure body retinol stores, as has been accomplished in the case of fatty acids and amino acids. Sample size requirements for GC-P-IRMS may exceed those of GCMS, but this paper discusses sample preparation procedures and predicts improvements, particularly in the efficiency of sample introduction. PMID:25537104

  10. Stable iron isotope fractionation between aqueous Fe(II) and hydrous ferric oxide.

    PubMed

    Wu, Lingling; Beard, Brian L; Roden, Eric E; Johnson, Clark M

    2011-03-01

    Despite the ubiquity of poorly crystalline ferric hydrous oxides (HFO, or ferrihydrite) in natural environments, stable Fe isotopic fractionation between HFO and other Fe phases remains unclear. In particular, it has been difficult to determine equilibrium Fe isotope fractionation between aqueous Fe(II) and HFO due to fast transformation of the latter to more stable minerals. Here we used HFO stabilized by the presence of dissolved silica (2.14 mM), or a Si-HFO coprecipitate, to determine an equilibrium Fe(II)-HFO fractionation factor using a three-isotope method. Iron isotope exchange between Fe(II) and HFO was rapid and near complete with the Si-HFO coprecipitate, and rapid but incomplete for HFO in the presence of dissolved silica, the latter case likely reflecting blockage of oxide surface sites by sorbed silica. Equilibrium Fe(II)-HFO (56)Fe/(54)Fe fractionation factors of -3.17 ± 0.08 (2?)‰ and -2.58 ± 0.14 (2?)‰ were obtained for HFO plus silica and the Si-HFO coprecipitate, respectively. Structural similarity between ferrihydrite and hematite, as suggested by spectroscopic studies, combined with the minor isotopic effect of dissolved silica, imply that the true equilibrium Fe(II)-HFO (56)Fe/(54)Fe fractionation factor in the absence of silica may be ?-3.2‰. These results provide a critical interpretive context for inferring the stable isotope effects of Fe redox cycling in nature. PMID:21294566

  11. Influence of regional precipitation patterns on stable isotopes in ice cores from the central Himalayas

    NASA Astrophysics Data System (ADS)

    Pang, H.; Hou, S.; Kaspari, S.; Mayewski, P. A.

    2014-02-01

    Several ice cores have been recovered from the Dasuopu (DSP) Glacier and the East Rongbuk (ER) Glacier in the central Himalayas since the 1990s. Although the distance between the DSP and the ER ice core drilling sites is only ~ 125 km, the stable isotopic record (?18O or ?D) of the DSP core is interpreted in previous studies as a temperature proxy, while the ER core is interpreted as a precipitation proxy. Thus, the climatological significance of the stable isotopic records of these Himalayan ice cores remains a subject of debate. Based on analysis of regional precipitation patterns over the region, we find that remarkable discrepancy in precipitation seasonality between the two sites may account for their disparate isotopic interpretations. At the ER core site, the Indian summer monsoon (ISM) precipitation is dominating due to topographic blocking of the moisture from westerlies by the high ridges of Mt. Qomolangma (Everest), which results in a negative correlation between the ER ?18O or ?D record and precipitation amount along the southern slope of the central Himalayas in response to the "amount effect". At the DSP core site, in comparison with the ISM precipitation, the wintertime precipitation associated with the westerlies is likely more important owing to its local favorable topographic conditions for interacting with the western disturbances. Therefore, the DSP stable isotopic record may be primarily controlled by the westerlies. Our results have important implications for interpreting the stable isotopic ice core records recovered from different climatological regimes of the Himalayas.

  12. Influence of weather on the stable isotopic ratios of wines: Tools for weather/climate reconstruction?

    NASA Astrophysics Data System (ADS)

    Ingraham, Neil L.; Caldwell, Eric A.

    1999-01-01

    Precipitation, local ground water, soil water, atmospheric water vapor, grape leaf and grape berry water just prior to harvest, and grape must during the wine-making process, from the Napa Valley in northern California were collected for stable isotopic analysis. In addition, 27 red wines and 4 white wines produced in the Napa Valley, and 8 red wines produced in Livermore Valley located over 110 km to the southeast, were analyzed for both oxygen and hydrogen isotopic compositions. The isotopic compositions of the grape leaf water fall on a transpiration line with a slope of 2.1, while those of the grape berry water fall on a transpiration line with a slope of 2.8. The stable isotopic compositions of the 27 red wines from the Napa Valley range from -3 to +20‰ in ?D and from +4.6 to + 10.2‰ in ?18O and plot along a line described by ?D = 3.4 ?18O - 17.2. The maximum difference in the stable oxygen composition between two wineries 110 km apart is only 1.4‰, while the differences between the vintage years within each winery are 4.8 and 5.8‰ in ?18O. The stable isotopic composition of the grape water is controlled by transpiration in the weeks prior to harvest, overshadowing all other effects. As a result of the timing of harvest, the red wines are some 4 to 5‰ more enriched in ?18O than the white wines.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    The lipid biomarkers of hopanoids in cold seep carbonates from the South China Sea continental slope were investigated by gas chromatography-mass spectrometer (GC-MS) and gas chromatography-isotope ratio-mass spectrometer (GC-ir-MS). The distribution of hopanes/hopenes shows a preference for the ‘biological’ 17?(H), 21?(H)-over the ‘geological’ 17?(H), 21?(H)-configuration. This interpretation is in agreement with the strong odd-even preference of long-chain n-alkanes in those samples, suggesting that the ?? hopanes may be the early diagenetic products of biohopanoids and the ??, ?? configurations of hopanes were mainly derived from allochthonous sources contributing to the organic matter of the carbonates. In terms of hopanoid acids, the C30 to C33 17?(H), 21?(H)-hopanoid acids were detected with C32 17?(H), 21?(H)-hopanoid acid being the most abundant. However, there is a significant difference in stable carbon isotopic compostions of the C32 17?(H), 21?(H)-hopanoic acid among samples (-30.7‰ to -69.8‰). The ?13C values match well with the carbon isotopic compositions of SRB-derived iso-/anteiso-C15:0 fatty acids in the samples, which strongly depend on the carbon utilization types by microbe. The most abundant compound of hopanols detected in the samples, C30-17?(H), 21?(H)-hopanol, may be a good indicator of diagenetic product of type I methanotrophs. The molecular and carbon isotopic compositions of hopanoids demonstrate clearly that there is a combination contribution of both SRB and type I or type X methanotrophs to the source organism in the seep carbonates from the South China Sea continental slope.

  14. A novel sample decomposition technique at atmospheric pressure for the determination of Os abundances in iron meteorites using isotope dilution inductively coupled plasma-mass spectrometry.

    PubMed

    Hattori, M; Hirata, T

    2001-06-01

    A safe and reliable analytical technique for the determination of Os abundances in ten iron meteorites of various chemical groups was developed using isotope dilution inductively coupled plasma-mass spectrometry coupled with a sample decomposition technique. A major advantage of the sample decomposition technique developed here is that the pressure inside the reaction flask is not increased through the decomposition reaction because the flask is a fully opened system, obviating the risk of explosion of the glass apparatus. Another advantage is that there is no restriction in the sample size being decomposed. In this study, about 2 g of metallic sample were decomposed safely, and this sample size, > 10 times larger than that typically used for the Carius tube technique, allows one to obtain more reliable Os data for heterogeneous samples. The metallic samples were decomposed in a glass flask purged with Ar. Since the O2 was purged from the reaction flask, Os was not oxidised to volatile OsO4, thereby preventing significant evaporation loss of Os. The typical recovery of Os throughout the sample decomposition and separation processes was > 80%, and the total Os blank through the decomposition of a 1 g amount of sample was less than 20 pg. Os abundances were determined by means of stable isotope dilution mass spectrometry using a 190Os-enriched isotopic tracer. Except for Sikhote-Alin, the measured Os abundances in almost all the iron meteorites exhibited a good agreement with the previously published Os abundance data, within the analytical uncertainty achieved in this study (2-5%). For the Sikhote-Alin meteorite, on the basis of a better correlation between Os and Ir abundances, we believe that our Os abundance data should be more reliable. The Os abundance data obtained in this work clearly demonstrated the suitability of the newly developed sample decomposition procedure for low level Os determinations. PMID:11445949

  15. Monitoring water stable isotope composition in soils using gas-permeable tubing and infrared laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Rothfuss, Youri; Vereecken, Harry; Brüggemann, Nicolas

    2013-04-01

    The water stable isotopologues 1H2H16O and 1H218O are powerful tracers of processes occurring in nature. Their slightly different masses as compared to the most abundant water isotopologue (1H216O) affect their thermodynamic (e.g. during chemical equilibrium reactions or physical phase transitions with equilibration) and kinetic (liquid and vapor phases transport processes and chemical reactions without equilibration) properties. This results in measurable differences of the isotopic composition of water within or between the different terrestrial ecosystem compartments (i.e. sub-soil, soil, surface waters, plant, and atmosphere). These differences can help addressing a number of issues, among them water balance closure and flux partitioning from the soil-plant-atmosphere continuum at the field to regional scales. In soils particularly, the isotopic composition of water (?2H and ?18O) provides qualitative information about whether water has only infiltrated or already been re-evaporated since the last rainfall event or about the location of the evaporation front. From water stable isotope composition profiles measured in soils, it is also possible, under certain hypotheses, to derive quantitative information such as soil evaporation flux and the identification of root water uptake depths. In addition, water stable isotopologues have been well implemented into physically based Soil-Vegetation-Atmosphere Transfer models (e.g. SiSPAT-Isotope; Soil-Litter iso; TOUGHREACT) and have demonstrated their potential. However, the main disadvantage of the isotope methodology is that, contrary to other soil state variables that can be monitored over long time periods, ?2H and ?18O are typically analyzed following destructive sampling. Here, we present a non-destructive method for monitoring soil liquid water ?2H and ?18O over a wide range of water availability conditions and temperatures by sampling and measuring water vapor equilibrated with soil water using gas-permeable polypropylene tubing and a cavity ring-down laser absorption spectrometer. By analyzing water vapor ?2H and ?18O sampled with the tubing from a fine sand for temperatures ranging between 8-24° C, we demonstrate that (i) our new method is capable of monitoring ?2H and ?18O in soils online with high precision and, after calibration, also with high accuracy, (ii) our sampling protocol enabled detecting changes of ?2H and ?18O following non-fractionating addition and removal of liquid water and water vapor of different isotopic compositions, and (iii) the time needed for the tubing to monitor these changes is compatible with the observed variations of ?2H and ?18O in soils under natural conditions.

  16. Isotope Tutorial (title provided or enhanced by cataloger)

    NSDL National Science Digital Library

    Diane Pataki

    This isotope tutorial explains what isotopes are and what units are used to express them, how measurements of isotopes are made, and how natural variation in stable isotope abundances come about. The site describes processes affecting isotope ratios such as photosynthesis, evapotranspiration, and respiration; biosphere-atmosphere exchange of isotopes in water and carbon; and how stable isotopes are used to study environmental history. There is information on courses in stable isotopes and the Biosphere - Atmosphere Stable Isotope Network (BASIN) project aimed at improving understanding of carbon cycle processes at the ecosystem, regional, and global scale. Links are provided to analytical labs.

  17. Stable isotope analysis of precipitation samples obtained via crowdsourcing reveals the spatiotemporal evolution of Superstorm Sandy.

    PubMed

    Good, Stephen P; Mallia, Derek V; Lin, John C; Bowen, Gabriel J

    2014-01-01

    Extra-tropical cyclones, such as 2012 Superstorm Sandy, pose a significant climatic threat to the northeastern United Sates, yet prediction of hydrologic and thermodynamic processes within such systems is complicated by their interaction with mid-latitude water patterns as they move poleward. Fortunately, the evolution of these systems is also recorded in the stable isotope ratios of storm-associated precipitation and water vapor, and isotopic analysis provides constraints on difficult-to-observe cyclone dynamics. During Superstorm Sandy, a unique crowdsourced approach enabled 685 precipitation samples to be obtained for oxygen and hydrogen isotopic analysis, constituting the largest isotopic sampling of a synoptic-scale system to date. Isotopically, these waters span an enormous range of values (> 21‰ for ?(18)O, > 160‰ for ?(2)H) and exhibit strong spatiotemporal structure. Low isotope ratios occurred predominantly in the west and south quadrants of the storm, indicating robust isotopic distillation that tracked the intensity of the storm's warm core. Elevated values of deuterium-excess (> 25‰) were found primarily in the New England region after Sandy made landfall. Isotope mass balance calculations and Lagrangian back-trajectory analysis suggest that these samples reflect the moistening of dry continental air entrained from a mid-latitude trough. These results demonstrate the power of rapid-response isotope monitoring to elucidate the structure and dynamics of water cycling within synoptic-scale systems and improve our understanding of storm evolution, hydroclimatological impacts, and paleo-storm proxies. PMID:24618882

  18. Stable Isotope Ratios as a Tool in Microbial Forensics—Part 1. Microbial Isotopic Composition as a Function of Growth Medium

    Microsoft Academic Search

    Helen W. Kreuzer-Martin; Lesley A. Chesson; Michael J. Lott; Janet V. Dorigan; James R. Ehleringer

    2004-01-01

    The stable isotope ratios of a seized pathogen culture could potentially reveal information about the environment in which the agent was produced. In this paper we describe general relationships between stable isotopes of carbon, nitrogen, and hydrogen in bacteriological culture media and spores of Bacillus subtilis, an endospore-forming soil bacterium. In numerous media that varied both in nutrient composition and

  19. Stable isotope records from Sepia officinalis—a key to understanding the ecology of belemnites?

    NASA Astrophysics Data System (ADS)

    Rexfort, A.; Mutterlose, J.

    2006-07-01

    The stable isotope ratios (? 18O, ? 13C) of the aragonite of cuttlebones of Sepia officinalis were measured on a high resolution scale where every septum was measured. Our studies aim at understanding whether variations of the isotope signature are controlled by ontogenetic and/or ecological factors. Five specimens were reared from eggs under known water temperatures, a sixth specimen was caught in the German part of the North Sea. The data suggest that the oxygen isotope composition is in isotopic equilibrium with the surrounding seawater and reflects ambient temperature. Migration and seasonal temperature changes are visible in the acquired data set. The carbon isotope signature shows signs of biofractionation and no direct correlation to the oxygen signature as far as ontogeny and ecology are concerned.

  20. Stable Sulfur Isotopic Evidence for Historical Changes of Sulfur Cycling in Estuarine Sediments from Northern Florida

    Microsoft Academic Search

    Volker Brüchert; Lisa M. Pratt

    1999-01-01

    Data on abundance and isotopic composition of porewater and sedimentary sulfur species are reported for relatively uncontaminated and highly contaminated fine-grained anoxic sediments of St. Andrew Bay, Florida. A strong contrast in amount and composition of sedimentary organic matter at the two sites allows a comparative study of the historical effects of increased organic loading on sulfur cycling and sulfur

  1. Use of Stable Isotopes to Investigate Keratin Deposition in the Claw Tips of Ducks

    PubMed Central

    Hopkins, John B.; Cutting, Kyle A.; Warren, Jeffrey M.

    2013-01-01

    Stable isotopes derived from the claws of birds could be used to determine the migratory origins of birds if the time periods represented in excised sections of claws were known. We investigated new keratin growth in the claws of adult female Lesser Scaup (Aythya affinis) by estimating the equilibration rates of stable isotopes (?13C, ?15N, and ?2H) from the breeding grounds into 1 mm claw tips. We sampled birds on their breeding ground through time and found that it took approximately 3–3.5 months for isotope values in most claw tips to equilibrate to isotope values that reflected those present in the environment on their breeding grounds. Results from this study suggest that isotopes equilibrate slowly into claw tips of Lesser Scaup, suggesting isotopes could potentially be used to determine the wintering grounds of birds. We suggest using controlled feeding experiments or longitudinal field investigations to understand claw growth and isotopic equilibration in claw tips. Such information would be valuable in ascertaining whether claw tips can be used in future studies to identify the migratory origins of birds. PMID:24282563

  2. Use of stable isotopes to investigate keratin deposition in the claw tips of ducks.

    PubMed

    Hopkins, John B; Cutting, Kyle A; Warren, Jeffrey M

    2013-01-01

    Stable isotopes derived from the claws of birds could be used to determine the migratory origins of birds if the time periods represented in excised sections of claws were known. We investigated new keratin growth in the claws of adult female Lesser Scaup (Aythya affinis) by estimating the equilibration rates of stable isotopes (? (13)C, ? (15)N, and ? (2)H) from the breeding grounds into 1 mm claw tips. We sampled birds on their breeding ground through time and found that it took approximately 3-3.5 months for isotope values in most claw tips to equilibrate to isotope values that reflected those present in the environment on their breeding grounds. Results from this study suggest that isotopes equilibrate slowly into claw tips of Lesser Scaup, suggesting isotopes could potentially be used to determine the wintering grounds of birds. We suggest using controlled feeding experiments or longitudinal field investigations to understand claw growth and isotopic equilibration in claw tips. Such information would be valuable in ascertaining whether claw tips can be used in future studies to identify the migratory origins of birds. PMID:24282563

  3. Stable Carbon Isotope Constraints on the Timing and Magnitude of Phytoplankton Blooms in San Francisco Bay

    NASA Astrophysics Data System (ADS)

    Goodwin, D.; Roopnarine, P. D.

    2010-12-01

    Recent work on phytoplankton dynamics in San Francisco Bay (SFB) revealed new seasonal blooms. Historic observations (1978-1998) of chlorophyll a (Chl a) showed an annual pattern of short-lived spring blooms. In 1999, this pattern changed with the appearance of autumnal blooms in addition to the characteristic large vernal blooms. This change was attributed to decreases in bivalve mollusk populations concurrent with increases in macro invertebrate and vertebrate mollusk predators. Previous work, however, suggests that inter-annual variation in phytoplankton biomass is a function of river discharge. These observations suggest phytoplankton abundances in SFB reflect multiple forcing mechanisms and underscore the importance of understanding prehistoric variations in bloom dynamics. Here, we present stable isotope data from the exotic oyster Crassostrea gigas, which record the timing and magnitude of past phytoplankton blooms. These data may be useful for identifying patterns of phytoplankton bloom dynamics prior to instrumental observations. Stable oxygen (?18O) and carbon (?13C) isotope profiles from recent live-collected (2006) specimens of the oyster C. gigas collected in southern SFB were analyzed in conjunction with in situ records of environmental variability (water temperature and ?18Owater calculated from salinity). Their observed ?18Ocarb profiles are characterized by several unique features that correlate with predicted ?18Ocarb values calculated from water temperature and ?18Owater measurements indicating that these oysters were recruited at the end of 2001 or early in 2002. A prominent 1-2 ‰ spike characterizes the carbon isotope profile from each of these specimens. These positive excursions most likely reflect a large phytoplankton bloom, during which algae preferentially assimilated 12C, resulting in the enrichment of 13C in the dissolved inorganic carbon (DIC) of seawater. Furthermore, phytoplankton blooms may appear as positive spikes in a shell’s carbon isotope profile because bivalve shell ?13C, in part, reflects ?13CDIC. Chl a concentrations, collected by the USGS at two locations in southern SFB, show that a large phytoplankton bloom (Chl a >60 mg/m3) occurred in the spring of 2003. These data suggest C. gigas record phytoplankton blooms with Chl a concentrations >60 mg/m3. However, because several smaller blooms (Chl a 10-50 mg/m3) occurred during the lifetime of these individuals, it appears that 60 mg/m3 represents a threshold, below which blooms are not recorded. On the other hand, the inability to observe smaller blooms may reflect limits imposed by sample resolution. This study suggests prehistoric oysters—and perhaps other bivalve mollusk species—that lived in SFB contain a valuable archive of large phytoplankton blooms. Furthermore, high-resolution sampling approaches may shed light on past smaller scale intra- and inter-annual bloom dynamics.

  4. Global scale observations of atmospheric molecular hydrogen and its stable isotopic composition

    NASA Astrophysics Data System (ADS)

    Batenburg, A. M.

    2012-09-01

    With average mixing ratios (?) around 550 ppb (nmole/mole), molecular hydrogen (H2) is the most abundant reduced gas in our atmosphere after methane (CH4), but considerably less studied. H2 is also a promising energy carrier that might replace fossil fuels in vehicles with great sustainability advantages, but there may be environmental side effects. Large-scale leakage of H2 into the atmosphere might affect the atmosphere’s oxidative capacity and stratospheric ozone chemistry. To assess these risks, a better understanding of the atmospheric H2 cycle is needed. Stable isotopic composition measurements can be used to constrain the source and sink terms in the budgets of atmospheric trace gases, as the different processes affect the stable isotopic composition of the gases in different ways. For H2, the effects are particularly large, due to the large relative mass difference between the isotopes (H and D). The largest source, hydrocarbon oxidation, yields D-enriched H2, whereas the smaller combustion-related sources and the minor microbial sources yield D-depleted and extremely D-depleted H2, respectively. Both sink processes, uptake in soils and reaction with hydroxyl radicals (OH), have a D-enriching effect, but the effect is much stronger for OH. Despite its usefulness, few environmental observations of H2 isotopic composition (?D(H2)) are available. We present three new ?(H2) and ?D(H2) datasets to fill this gap. First, we present one- to five-year long time series from six globally distributed, predominantly background stations. As expected, average ?(H2) and ?D(H2) values were larger in the southern hemisphere (SH) than in the northern hemisphere (NH). The minimum in ?D(H2) was found at the NH midlatitude stations, likely a result of fossil fuel combustion. At the three NH coastal and island stations, seasonal ?D(H2)-cycles were observed, which were five to six months out-of-phase with the ?(H2)-cycles. No ?D(H2)-cycles were observed at the other sites. For the three coastal/island NH stations, a tentative analysis was made of the relative contribution of the two sink processes. This indicated that the relative contribution of soil uptake increases with latitude. In the next chapter, ?D(H2) data are presented from samples collected by the CARIBIC passenger aircraft. This commercial aircraft flies in the upper troposphere (UT) but also regularly crosses into the lowermost stratosphere (LMS). In the LMS, tight correlations are found between ?D(H2) and ?(CH4). This correlation has applications in global models of ?D(H2). UT samples collected over India during the summer monsoon show a decrease in ?D(H2) that is correlated with a CH4 increase, possibly indicating a previously unknown microbial H2-source. Lastly, we present a three-year long time series from the Cabauw tall tower in the Netherlands (200 m), which shows excursions to high ?(H2) and low ?D(H2) values, especially in winter. These indicate that the local H2-cycle is under heavy anthropogenic influence, which is confirmed by an analysis of the apparent source signature. In addition, several height profiles (20, 60, 120 and 200 m) were measured. These show that the local soil uptake of H2 is weak

  5. The use of Mössbauer spectroscopy in stable isotope geochemistry

    NASA Astrophysics Data System (ADS)

    Polyakov, Veniamin B.; Mineev, Sergey D.

    2000-03-01

    The use of Mössbauer spectroscopic data on the second-order Doppler (SOD) shift to determine the reduced isotopic partition function ratio (?-factor) has been considered by the example of iron. Using the relation between the ?-factor and the SOD shift in Mössbauer spectra, the temperature dependence of the iron ?-factors for a wide range of minerals has been evaluated from experimental data on the SOD shift. It is shown that the ?-factors of Fe 3+ ions are considerably higher than those of Fe 2+. The curve describing the temperature dependence of the ?-factor for native iron is the boundary separating fields that are typical for ferric and ferrous ions. The value of the iron ?-factor increases with increasing covalence of chemical bonds. In the case of covalent chemical bonds, the iron ?-factor achieves high values even for ferrous compounds. Possible iron isotope geothermometers magnetite-siderite and pyrite-siderite have been calibrated 10 3 ln ? magnetite-siderite=0.881 776 x-0.544 105×10 -2x2+0.425 639 10 -4x3-0.352 191×10 -5x4, 10 3 ln ? pyrite-siderite=0.913 717 x-0.557 721×10 -2x2+0.424 146×10 -4x3-0.334 281×10 -5x4, where x = 10 6/ T2, T is absolute temperature, ln ? relates to 57Fe/ 54Fe fractionation. At equilibrium, a small iron isotopic shift between magnetite and pyrite along with high iron isotopic shifts between magnetite and siderite and between pyrite and siderite should be observed. A significant effect (about 7‰ at 300 K) of the aluminum substitution on the iron ?-factor in hematite has been evaluated from the appropriate data on the SOD shift in Mössbauer spectra. The analogous effect of the Co-substitution in magnetite is lower (?3.0‰ at 300 K). A new method of evaluation of the ?-factor for isotopes traditionally used in geochemical studies like sulfur, oxygen, etc., is suggested. The method uses experimental Mössbauer data on the SOD shift and calorimetric data on the heat capacity. The method can be applied to compounds consisting of two chemical elements (like oxides, sulfides) if one of them has a Mössbauer-sensitive isotope. Using the new method, the ? 34S-factor of pyrite and the ? 18O-factor of hematite have been determined: 10 3 ln ? pyrite=(1.5997±0.0419) x-(6.7744±0.4279)×10 -3x2+(3.8254±0.5682)×10 -5x3, 10 3 ln ? hematite=(5.7215±0.3891) x-(0.029 41±0.004 49) x2.

  6. Determination of hexavalent chromium reduction using Cr stable isotopes: isotopic fractionation factors for permeable reactive barrier materials.

    PubMed

    Basu, Anirban; Johnson, Thomas M

    2012-05-15

    Cr stable isotope measurements can provide improved estimates of the extent of Cr(VI) reduction to less toxic Cr(III). The relationship between observed (53)Cr/(52)Cr ratio shifts and the extent of reduction can be calibrated by determining the isotopic fractionation factor for relevant reactions. Permeable reactive barriers (PRB) made of Fe(0) and in situ redox manipulation (ISRM) zones effectively remediate Cr-contaminated aquifers. Here, we determine the isotopic fractionations for dominant reductants in reactive barriers and reduced sediments obtained from an ISRM zone at the US DOE's Hanford site. In all cases, significant isotopic fractionation was observed; fractionation (expressed as ?) was -3.91‰ for Fe(II)-doped goethite, -2.11‰ for FeS, -2.65‰ for green rust, -2.67‰ for FeCO(3), and -3.18‰ for ISRM zone sediments. These results provide a better calibration of the relationship between Cr isotope ratios and the extent of Cr(VI) reduction and aid in interpretation of Cr isotope data from systems with reactive barriers. PMID:22424120

  7. Table I. Column 4, labelled f, lists isotopic abundance fractions from Anders and Grevesse [11]. Columns 5 through 7 are from Table of Isotopes [12]. Column

    E-print Network

    Kurucz, Robert L.

    Table I. Column 4, labelled f, lists isotopic abundance fractions from Anders and Grevesse [11]. Columns 5 through 7 are from Table of Isotopes [12]. Column 5, labelled I, is the nuclear spin. Column 6, labelled ¯, is the magnetic dipole moment in nuclear magnetons. Column 7, labelled Q, is the electric

  8. Establishing pathways of energy flow for insect predators using stable isotope ratios: field and laboratory evidence

    Microsoft Academic Search

    P. H. Ostrom; Manuel Colunga-Garcia; Stuart H. Gage

    1996-01-01

    Quantifying pathways of energy transfer between plants, pests, and beneficial insects is a necessary step toward maintaining\\u000a pest stable agroecosystems in the absence of chemical subsidies. A diet switching experiment utilizing a predatory ladybird\\u000a beetle, Hippodamia variegata (Goeze), evaluated the use of naturally occurring stable C and N isotopes as an economically feasible and safe method for\\u000a quantifying pathways of

  9. Seasonal variation of stable isotopic compositions recorded in a laminated tufa, SW Japan

    Microsoft Academic Search

    J. Matsuoka; A. Kano; T. Oba; T. Watanabe; S. Sakai; K. Seto

    2001-01-01

    High-resolution stable isotopic analyses of an annually laminated tufa from Shirokawa, SW Japan, show cyclic variations that correspond to mm-scale summer (dense) and winter (porous) laminae. Both ?18O and ?13C values are high in winter and low in summer, and correlate well with each other (r=0.88). Because the ?18O content of stream water has remained relatively stable over time, the

  10. Stable isotope quality assurance using the 'calibrated IRMS' strategy.

    PubMed

    Meijer, Harro A J

    2009-06-01

    Procedures in our laboratory have always been directed towards complete understanding of all processes involved and corrections needed etc., instead of relying fully on laboratory reference materials. This rather principal strategy (or attitude) is probably not optimal in the economic sense, and is not necessarily more accurate either. Still, it has proven to be very rewarding in its capability to detect caveats that go undiscovered in the standard way of measurement, but that do influence the accuracy or reliability of the measurement procedure. An additional benefit of our laboratory procedures is that it makes us capable of assisting the International Atomic Energy Agency (IAEA) with primary questions like mutual scale assignments and comparison of isotope ratios of the same isotope in different matrices (like delta(18)O in water, carbonates and atmospheric CO(2)), establishment of the (17)O-(18)O relation, and the replenishment of the calibration standards. Finally, for manual preparation systems with a low sample throughput (and thus only few reference materials analysed) it may well be the only way to produce reliable results. PMID:20183228

  11. Stable isotope paleoaltimetry: Tectonics and the evolution of landscapes and life

    NASA Astrophysics Data System (ADS)

    Mulch, Andreas

    2015-04-01

    Stable isotope paleoaltimetry exploits systematic changes in the oxygen (?18O) or hydrogen (?D) isotopic composition of precipitation when lifting of moist air masses over topography induces orographic precipitation. The past 10 years have witnessed rapidly expanding research activities in stable isotope paleoaltimetry that resulted in a broad array of fascinating tectonic studies many of which concentrated on the elevation histories of continental plateau regions. Stable isotope based reconstructions of topography, therefore, have greatly expanded what used to be very sparse global paleoaltimetric information. The topography of mountain ranges and plateaus, however, not only reflects the geodynamic processes that shape the Earth's surface; it also represents a key element in controlling continental moisture transport, atmospheric circulation and the distribution of biomes and biodiversity. The challenge now lies in disentangling the surface uplift component from the inevitable impact of climate change on long-term records of ?18O and ?D in precipitation that accompanies surface uplift. The robustness of stable isotope paleoaltimetry reconstructions can be greatly enhanced when high-elevation ?18O or ?D proxy data are referenced against low-elevation records that track climate-modulated ?18O or ?D of precipitation through time. In addition, evaluating ?18O or ?D of precipitation upstream of the orogen/continental plateau region reduces commonly encountered complexities such as topographic threshold conditions to atmospheric circulation, variable moisture recharge to the atmosphere through evapotranspiration over the continents or the impact of hemispheric-scale atmospheric teleconnections; all of which may conspire in setting ?18O or ?D of precipitation. Here, I present examples where stable isotope paleoaltimetry data successfully track topographic thresholds to changes in atmospheric circulation and precipitation with a particular focus on the effect of plateau-bounding ranges and document how a) spatially distributed proxy data permit the reconstruction of atmospheric circulation (and precipitation) patterns and b) how differences in ?18O between high and low-elevation sites may enhance the robustness of stable isotope paleoaltimetry data. Future advances in stable isotope paleoaltimetry will greatly benefit from addressing topographically-induced teleconnections in the global climate system that affect ?18O or ?D of precipitation and from interfacing with evolutionary biology/phylogenetic techniques to evaluate competing hypotheses with respect to the timing of surface uplift.

  12. Enhanced understanding of ectoparasite–host trophic linkages on coral reefs through stable isotope analysis

    PubMed Central

    Demopoulos, Amanda W.J.; Sikkel, Paul C.

    2015-01-01

    Parasitism, although the most common type of ecological interaction, is usually ignored in food web models and studies of trophic connectivity. Stable isotope analysis is widely used in assessing the flow of energy in ecological communities and thus is a potentially valuable tool in understanding the cryptic trophic relationships mediated by parasites. In an effort to assess the utility of stable isotope analysis in understanding the role of parasites in complex coral-reef trophic systems, we performed stable isotope analysis on three common Caribbean reef fish hosts and two kinds of ectoparasitic isopods: temporarily parasitic gnathiids (Gnathia marleyi) and permanently parasitic cymothoids (Anilocra). To further track the transfer of fish-derived carbon (energy) from parasites to parasite consumers, gnathiids from host fish were also fed to captive Pederson shrimp (Ancylomenes pedersoni) for at least 1 month. Parasitic isopods had ?13C and ?15N values similar to their host, comparable with results from the small number of other host–parasite studies that have employed stable isotopes. Adult gnathiids were enriched in 15N and depleted in 13C relative to juvenile gnathiids, providing insights into the potential isotopic fractionation associated with blood-meal assimilation and subsequent metamorphosis. Gnathiid-fed Pedersen shrimp also had ?13C values consistent with their food source and enriched in 15N as predicted due to trophic fractionation. These results further indicate that stable isotopes can be an effective tool in deciphering cryptic feeding relationships involving parasites and their consumers, and the role of parasites and cleaners in carbon transfer in coral-reef ecosystems specifically. PMID:25830112

  13. Nuclear Volume Effects in Equilibrium Stable Isotope Fractionations of Hg, Tl and Pb Isotope Systems

    NASA Astrophysics Data System (ADS)

    Yang, S.; Liu, Y.

    2014-12-01

    Many evidences showed that heavy isotope systems could be significantly fractionated as the consequence of the nuclear volume effect (NVE) or so-called nuclear field shift effect. Here we investigate NVEs of Hg, Tl and Pb isotope systems by using quantum chemistry computational methods with careful evaluation on quantum relativistic effects via the Dirac's formalism of full-electron wavefunction. Our results generally agree with previous studies but with noticeable differences in many cases. With the unique NVE driving force, equilibrium 202Hg/198Hg and 205Tl/203Tl isotopes can be fractionated up to 3.94‰ and 2.78‰ at 0?, respectively, showing potentially large equilibrium isotope fractionations can be expected for future studies of these two isotope systems. Moreover, the NVE causes large mass-independent fractionations (MIF) for odd-mass isotopes (e.g., ?199NVHg and ?201NVHg) and small MIFs for even-mass isotopes (e.g., ?200NVHg). For Pb isotope system, NVEs induce isotope fractionations up to 1.62‰ (207Pb/206Pb) and 4.06‰ (208Pb/206Pb) at 0?. However, contributions from classical mass-dependent driving force are small, about 0.1-0.5‰ for 207Pb/206Pb and 0.2-0.9‰ for 208Pb/206Pb. We find that Pb4+-bearing species can be significantly enriched heavy isotopes than Pb2+-bearing species. Comparing to Pb0, Pb2+-bearing species even enrich lighter Pb isotopes. A very strange and interesting thing is that the beta value of Pb2+-bearing species can be smaller than the unity (1.000). Similar thing has been found on Tl+-bearing species. This is an impossible and unexplained situation if only based on classical mass-dependent isotope fractionation theory (e.g., Bigeleisen-Mayer equation). The consequence is that the different direction of beta values of Pb2+-bearing species will let the Pb isotope fractionation even larger when they fractionate with Pb4+-bearing species. Moreover, NVEs also cause mass-independent fractionation (MIF) of odd 207Pb isotopes (?207NVPb).

  14. Spectral analysis software improves confidence in plant and soil water stable isotope analyses performed by isotope ratio infrared spectroscopy (IRIS).

    PubMed

    West, A G; Goldsmith, G R; Matimati, I; Dawson, T E

    2011-08-30

    Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isotope analysis. Here we report two independent tests of this post-processing spectral analysis software on two IRIS systems, OA-ICOS (Los Gatos Research Inc.) and WS-CRDS (Picarro Inc.). Following a similar methodology to a previous study, we cryogenically extracted plant leaf water and soil water and measured the ?(2)H and ?(18)O values of identical samples by isotope ratio mass spectrometry (IRMS) and IRIS. As an additional test, we analyzed plant stem waters and tap waters by IRMS and IRIS in an independent laboratory. For all tests we assumed that the IRMS value represented the "true" value against which we could compare the stable isotope results from the IRIS methods. Samples showing significant deviations from the IRMS value (>2?) were considered to be contaminated and representative of spectral interference in the IRIS measurement. Over the two studies, 83% of plant species were considered contaminated on OA-ICOS and 58% on WS-CRDS. Post-analysis, spectra were analyzed using the manufacturer's spectral analysis software, in order to see if the software correctly identified contaminated samples. In our tests the software performed well, identifying all the samples with major errors. However, some false negatives indicate that user evaluation and testing of the software are necessary. Repeat sampling of plants showed considerable variation in the discrepancies between IRIS and IRMS. As such, we recommend that spectral analysis of IRIS data must be incorporated into standard post-processing routines. Furthermore, we suggest that the results from spectral analysis be included when reporting stable isotope data from IRIS. PMID:21755548

  15. Isotopic tracing of clear water sources in an urban sewer: A combined water and dissolved sulfate stable isotope approach

    Microsoft Academic Search

    J. Houhou; B. S. Lartiges; C. Guilmette; S. Poix; C. Mustin

    2010-01-01

    This paper investigates the potential of stable isotopes of both water (?D and ?OH2O18) and dissolved sulfate (?34S and ?OSO418) for determining the origin and the amount of clear waters entering an urban sewer. The dynamics of various hydrological processes that commonly occur within the sewer system such as groundwater infiltration, rainwater percolation, or stormwater release from retention basins, can

  16. Sr stable isotope composition of Earth, the Moon, Mars, Vesta and meteorites

    NASA Astrophysics Data System (ADS)

    Moynier, Frédéric; Agranier, Arnaud; Hezel, Dominik C.; Bouvier, Audrey

    2010-12-01

    High-precision stable Sr isotopic variations ( 88Sr/ 86Sr) are reported in a variety of terrestrial samples, martian and lunar meteorites, HED, undifferentiated primitive meteorites, chondrules and refractory inclusions. Almost all the whole-rock samples are isotopically indistinguishable at a 50 parts per million (ppm) level. The exceptions are CV and CO chondrites which are isotopically light and for which we believe that their isotopic composition is controlled by the proportion of refractory material. Five separated chondrules and one refractory inclusion from Allende are isotopically light, with ? 88/86Sr fractionations up to -1.73‰, whereas the matrix is enriched in the heavy isotopes (? 88/86Sr = + 0.66‰). The depletion in heavy isotopes observed in chondrules and refractory inclusions could be attributed to the condensation of a material already depleted in Sr, however, in that case more than 60% of the original material would be unaccounted. We propose instead that isotopic fractionation by electromagnetic sorting of ionized heavy Sr from neutral Sr in the early solar system for the origin of the fractionation observed in refractory inclusions and redistribution of Sr by aqueous alteration for the origin of the fractionation observed in chondrules and matrix. We conclude that CV and CO chondrites are not the primary building blocks for Earth and Mars.

  17. High-Temperature Equilibrium Isotope Fractionation of Non-Traditional Stable Isotopes: Experiments, Theory, and Applications (Invited)

    NASA Astrophysics Data System (ADS)

    Young, E. D.; Lazar, G. C.; Macris, C. A.; Manning, C. E.; Schauble, E. A.; Shahar, A.

    2013-12-01

    Experiments are crucial for validating our understanding of stable isotope fractionation at high temperatures. The three-isotope method has been applied with success in the Si, Mg, Fe, and Ni isotope systems to date. The results of these experiments can be compared with expectations from theory and measurements of natural samples. Qualitative insights into the partitioning of heavy and light isotopes between mineral phases are gained by treating the force constant for relevant bonds, Kf j, as electrostatic in origin. The ionic model, based on the mean bond strength as defined by Pauling, has obvious limitations but is useful for rationalizing structures and site occupancies in silicates and oxide minerals and is equally useful in formulating expectations for isotope fractionation between phases. In some cases, as in Fe isotopes in spinels, the expectations are contrary to predictions based on modeling but similar to observations in natural samples. Experimental verification is required. The force constant for a bond between cation i (Mg, Fe, etc.) and anion j (e.g., O) can be written in terms of mean bond strengths si and sj (as defined by Pauling) as Kf,ij = sisj e2 (1-n)/(4 ? ?? r3ij ) where ?o is the electric constant (vacuum permittivity for simplicity), e is the charge of an electron, n is the exponent in the Born-Mayer formulation for ion repulsion (Born and Mayer 1932), and rij is the interatomic spacing. This equation shows explicitly that larger values for the force constant Kf correspond to smaller coordination numbers (via si and sj). We therefore expect an inverse relationship between isotope ratios (heavy/light) and coordination of its oxygen bond partners in silicate and oxides minerals and this is verified in mantle minerals. Our work with Fe isotope partitioning in mantle spinels suggests that coordination may be equally important as oxidation state, recognizing that these distinctions are not orthogonal. Recent work on the Mg isotopic compositions of mantle minerals underscores the utility and complexity of inter-mineral partitioning of 25Mg/24Mg and 26Mg/24Mg and tests our understanding of the crystal chemical controls on isotope partitioning of the major rock-forming elements. In our initial work on mantle minerals we pointed out that the largest inter-mineral fractionation in the Mg isotopic system in many mantle xenoliths is between spinel and olivine owing to the presence of tetrahedral Mg in the former. The observation that ?25Mg spinel > ?25Mg pyroxene > ?25Mg olivine is consistent with our understanding of the bonding environment of Mg in these minerals and our data matched expectations from theory. This expectation from theory and measurements of natural samples has now been verified experimentally using the three-isotope method. Complexity arises with substitution of Cr and Fe in the spinel structure, again warranting further experimental calibration. Stable isotope ratios of the rock-forming elements provide not only new ways of estimating temperatures of formation and resetting, but also provide an independent method for identifying mineral parageneses. For example, we have found consistent evidence for isotopic disequilibrium between pyroxene and other phases in mantle xenoliths. The full potential of these isotope systems will only be realized with exhaustive exploration of the crystal chemical influences on inter-mineral fractionations.

  18. Incorporation of stable and radioactive isotopes via organoborane chemistry

    SciTech Connect

    Kabalka, G.W.

    1984-06-01

    An organic synthesis involving the use of organoboranes rather than the traditional substitution reactions and Grignard reagents for the rapid preparation of physiologically active materials labelled with short-lived isotopes is discussed in detail. The iodination reaction for incorporating I-123 or I-125 into compounds was found to proceed via an electrophilic attack by the iodine molecule on the electron-rich borax complex, did not require the presence of strong base, and was complete in 60 sec. The procedure also uses radiolabeled NaI rather than the more unstable iodine monochloride usually used. A similar procedure was developed for labelling compounds with Br-77. Other direct one-pot syntheses are described for incorporation of O-17, N-13, N-15, C-11, and C-13 into compounds very rapidly.

  19. Avian embryonic development does not change the stable isotope composition of the calcite eggshell.

    PubMed

    Maurer, G; Portugal, S J; Boomer, I; Cassey, P

    2011-01-01

    The avian embryo resorbs most of the calcium for bone formation from the calcite eggshell but the exact mechanisms of the resorption are unknown. The present study tested whether this process results in variable fractionation of the oxygen and carbon isotopes in shell calcium carbonate, which could provide a detailed insight into the temporal and spatial use of the eggshell by the developing embryo. Despite the uncertainty regarding changes in stable isotope composition of the eggshell across developmental stages or regions of the shell, eggshells are a popular resource for the analysis of historic and extant trophic relationships. To clarify how the stable isotope composition varies with embryonic development, the ?(13)C and ?(18)O content of the carbonate fraction in shells of black-headed gull (Larus ridibundus) eggs were sampled at four different stages of embryonic development and at five eggshell regions. No consistent relationship between the stable isotope composition of the eggshell and embryonic development, shell region or maculation was observed, although shell thickness decreased with development in all shell regions. By contrast, individual eggs differed significantly in isotope composition. These results establish that eggshells can be used to investigate a species' carbon and oxygen sources, regardless of the egg's developmental stage. PMID:21211467

  20. Long-term monitoring of stable isotopic compositions of precipitation over volcanic island, Jeju, Korea

    NASA Astrophysics Data System (ADS)

    Kim, Young-Hee; Koh, Dong-Chan; Park, Won-Bae; Bong, Yeon-Sik; Lee, Kwang-Sik; Lee, Jeonghoon

    2015-04-01

    Stable isotopic compositions of precipitation can be widely used to understand moisture transport in the atmosphere, proxies for paleoclimate and interactions between groundwater and precipitation. Over Jeju volcanic island, located southwest of the Korean Peninsula, precipitation penetrated directly into the highly permeable aquifer is the main source of groundwater. In this study, long-term stable isotopic compositions of precipitation over Jeju Island are characterized to describe spatial and temporal patterns for hydrology and paleoclimate. At fifteen sites from September 2000 to December 2003, precipitation samples were collected and analyzed by Isotope Ratio Mass Spectrometer at the Korea Basic Science Institute. Compared to Lee et al. (2003), the two seasonal local meteoric water lines widen, which may change the relative contributions of winter and summer season precipitation to the groundwater recharge. The precipitation isotopes are inversely correlated with precipitation amount in summer, whereas they do not show a strong correlation with surface air temperature. The precipitation isotopes monthly averaged relatively show a periodic function (R2=0.63 and 0.40 for hydrogen and oxygen, respectively), and deuterium excess (d-excess=?D-8×?18O) shows a strong pattern of quadratic function (R2=0.97), which is related to a seasonal change of air masses. Altitude effect of precipitation isotopes, which can be a clue to reveal sources of groundwater, can be observed in every aspect of the volcanic island (for the oxygen isotope, -0.14‰ for east and west, -0.18‰ for north and -0.085‰ for south per 100 m). Our analysis of precipitation isotopes will be helpful to provide limitations and opportunities for paleoclimate reconstruction using isotopic proxies and water movement from atmosphere to subsurface.

  1. Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii Determination

    E-print Network

    W. Nörtershäuser; R. Sánchez; G. Ewald; A. Dax; J. Behr; P. Bricault; B. A. Bushaw; J. Dilling; M. Dombsky; G. W. F. Drake; S. Götte; H. -J. Kluge; Th. Kühl; J. Lassen; C. D. P. Levy; K. Pachucki; M. Pearson; M. Puchalski; A. Wojtaszek; Z. -C. Yan; C. Zimmermann

    2010-12-17

    Changes in the mean-square nuclear charge radii along the lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear charge radii of light elements are of high interest due to the appearance of the nuclear halo phenomenon in this region of the nuclear chart. During the past years we have developed a new laser spectroscopic approach to determine the charge radii of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field shift of an 8 ms lifetime isotope with production rates on the order of only 10,000 atoms/s. The method was applied to all bound isotopes of lithium including the two-neutron halo isotope Li-11 at the on-line isotope separators at GSI, Darmstadt, Germany and at TRIUMF, Vancouver, Canada. We describe the laser spectroscopic method in detail, present updated and improved values from theory and experiment, and discuss the results.

  2. Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii Determination

    E-print Network

    Nörtershäuser, W; Ewald, G; Dax, A; Behr, J; Bricault, P; Bushaw, B A; Dilling, J; Dombsky, M; Drake, G W F; Götte, S; Kluge, H -J; Kühl, Th; Lassen, J; Levy, C D P; Pachucki, K; Pearson, M; Puchalski, M; Wojtaszek, A; Yan, Z -C; Zimmermann, C

    2010-01-01

    Changes in the mean-square nuclear charge radii along the lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear charge radii of light elements are of high interest due to the appearance of the nuclear halo phenomenon in this region of the nuclear chart. During the past years we have developed a new laser spectroscopic approach to determine the charge radii of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field shift of an 8 ms lifetime isotope with production rates on the order of only 10,000 atoms/s. The method was applied to all bound isotopes of lithium including the two-neutron halo isotope Li-11 at the on-line isotope separators at GSI, Darmstadt, Germany and at TRIUMF, Vancouver, Canada. We describe the laser spectroscopic method in detail, present updated and improved values from theory and experiment, and discuss the results.

  3. Stable water isotope simulation by current land-surface schemes:Results of IPILPS phase 1

    SciTech Connect

    Henderson-Sellers, A.; Fischer, M.; Aleinov, I.; McGuffie, K.; Riley, W.J.; Schmidt, G.A.; Sturm, K.; Yoshimura, K.; Irannejad, P.

    2005-10-31

    Phase 1 of isotopes in the Project for Intercomparison of Land-surface Parameterization Schemes (iPILPS) compares the simulation of two stable water isotopologues ({sup 1}H{sub 2} {sup 18}O and {sup 1}H{sup 2}H{sup 16}O) at the land-atmosphere interface. The simulations are off-line, with forcing from an isotopically enabled regional model for three locations selected to offer contrasting climates and ecotypes: an evergreen tropical forest, a sclerophyll eucalypt forest and a mixed deciduous wood. Here we report on the experimental framework, the quality control undertaken on the simulation results and the method of intercomparisons employed. The small number of available isotopically-enabled land-surface schemes (ILSSs) limits the drawing of strong conclusions but, despite this, there is shown to be benefit in undertaking this type of isotopic intercomparison. Although validation of isotopic simulations at the land surface must await more, and much more complete, observational campaigns, we find that the empirically-based Craig-Gordon parameterization (of isotopic fractionation during evaporation) gives adequately realistic isotopic simulations when incorporated in a wide range of land-surface codes. By introducing two new tools for understanding isotopic variability from the land surface, the Isotope Transfer Function and the iPILPS plot, we show that different hydrological parameterizations cause very different isotopic responses. We show that ILSS-simulated isotopic equilibrium is independent of the total water and energy budget (with respect to both equilibration time and state), but interestingly the partitioning of available energy and water is a function of the models' complexity.

  4. Back to the basics of stable isotope fractionation. A 'complete system' approach presented.

    NASA Astrophysics Data System (ADS)

    De Groot, Pier

    2015-04-01

    A presentation on kinetic and equilibrium fractionation is given, including the consequences of the different type of fractionation in interpreting isotopic values. It will be shown that change in isotopic distribution, that is a uni-directional change, is kinetic. If a system reaches a steady state situation, we reach an equilibrium situation. Both kinetic and equilibrium isotope fractionations are perfectly repeatable, as log as the same conditions are applied. Major difference between kinetic and equilibrium fractionation is that kinetic fractionation includes rate-dependence, while equilibrium fractionation does not. Based on these views on isotopic fractionation, we have to realise that very commonly only selected parts larger, complete systems are considered. If applying just a few variables of a complete systems means the variables not included in the study must be fixed in value, or do have influence, which than is neglected. Moreover, experimentally determined isotopic fractionations as know from literature generally represent relatively simple systems with controlled values of variables, which rarely is true in more complex, natural systems. Experimental isotope fractionations are correct for the conditions as given. Empirically obtained isotopic fractionations are more complex and depend on how well the variables of the system are defined. Now, extending this to the use of isotopic proxies, it has to be realised that in almost all cases it is assumed other variables are fixed, or they just are neglected. For instance, if we consider proxies on a specific stable isotope dataset, where first temperature and secondly salinity of water is determined from the same dataset, an invalid procedure is applied. Probably both variables determined the isotopic distribution, but it is not certain which part of the isotopic distribution was induced by temperature and which by salinity. It will be shown that such interpretations are invalid and thus incorrect.

  5. STABLE ISOTOPE RATIOS AND CONTAMINANT CONCENTRATIONS IN A SEWAGE - DISTORTED FOOD WEB

    EPA Science Inventory

    Concentrations of selected neutral organic contaminants and stable isotope ratios of carbon, nitrogen and deuterium/hydrogen in invertebrates and fish were compared from near a large, 60m deep municipal waste outfall near Los Angeles, California, where waste has a measurable infl...

  6. Quantitative approaches for analysing fluxes through plant metabolic networks using NMR and stable isotope labelling

    Microsoft Academic Search

    N. J. Kruger; R. G. Ratcliffe; A. Roscher

    2003-01-01

    The quantitative analysis of metabolic networks is a prerequisite for understanding the integration and regulation of plant metabolism and for devising rational approaches for manipulating resource allocation in plants. The analysis of steady state stable isotope labelling experiments using nuclear magnetic resonance (NMR) spectroscopy has developed into a powerful method for determining these fluxes in micro-organisms and its application to

  7. Foraging ecology of the endangered wood stork recorded in the stable isotope signature of feathers

    Microsoft Academic Search

    Christopher S. Romanek; Karen F. Gaines; Bryan A. L. Jr; Brisbin I. L. Jr

    2000-01-01

    Down feathers and regurgitant were collected from nestling wood storks (Mycteria americana) from two inland and two coastal breeding colonies in Georgia. The stable isotopic ratios of carbon ( 13 C\\/12 C) and nitrogen ( 15N\\/ 14N) in these materials were analyzed to gain insights into the natal origins of juvenile storks and the foraging activities of adults. Down feathers

  8. Stable Carbon and Oxygen Isotope Ratios of Otoliths Differentiate Winter Flounder (Pseudopleuonectes americanus) Habitats

    EPA Science Inventory

    Stable carbon (¿13C) and oxygen (¿18O) isotope ratios were measured in otoliths of juvenile winter flounder (Pseudopleuronectes americanus) collected from 18 nursery areas along the coast of Rhode Island, USA. Samples were obtained during June and July of 2002 from locations tha...

  9. Stable isotope analysis of fish mucus during a controlled diet switch

    EPA Science Inventory

    We have used a controlled diet switch in steelhead trout (Oncorhynchus mykiss) at the Oregon Hatchery Research Center to study the time rates of changes in stable isotopes of carbon and nitrogen (¿13C and ¿15N) in epidermal mucus, a rapidly responding ?tissue.? Because of the ra...

  10. Soil Phosphate Stable Oxygen Isotopes across Rainfall and Bedrock Alon Angert,*,

    E-print Network

    Alon, Angert

    calcium-bound inorganic phosphate. The resin-P values were in the range 14.5-21.2. A similar range, 15Soil Phosphate Stable Oxygen Isotopes across Rainfall and Bedrock Gradients Alon Angert,*, Tal of soil phosphate (18 Op) were suggested recently to be a tracer of phosphorus cycling in soils and plants

  11. Technical Note: Calcium and carbon stable isotope ratios as paleodietary indicators.

    PubMed

    Melin, Amanda D; Crowley, Brooke E; Brown, Shaun T; Wheatley, Patrick V; Moritz, Gillian L; Yit Yu, Fred Tuh; Bernard, Henry; DePaolo, Donald J; Jacobson, Andrew D; Dominy, Nathaniel J

    2014-08-01

    Calcium stable isotope ratios are hypothesized to vary as a function of trophic level. This premise raises the possibility of using calcium stable isotope ratios to study the dietary behaviors of fossil taxa and to test competing hypotheses on the adaptive origins of euprimates. To explore this concept, we measured the stable isotope composition of contemporary mammals in northern Borneo and northwestern Costa Rica, two communities with functional or phylogenetic relevance to primate origins. We found that bone collagen ?(13) C and ?(15) N values could differentiate trophic levels in each assemblage, a result that justifies the use of these systems to test the predicted inverse relationship between bioapatite ?(13) C and ?(44) Ca values. As expected, taxonomic carnivores (felids) showed a combination of high ?(13) C and low ?(44) Ca values; however, the ?(44) Ca values of other faunivores were indistinguishable from those of primary consumers. We suggest that the trophic insensitivity of most bioapatite ?(44) Ca values is attributable to the negligible calcium content of arthropod prey. Although the present results are inconclusive, the tandem analysis of ?(44) Ca and ?(13) C values in fossils continues to hold promise for informing paleodietary studies and we highlight this potential by drawing attention to the stable isotope composition of the Early Eocene primate Cantius. PMID:24839035

  12. MixSIAR: A Bayesian stable isotope mixing model for characterizing intrapopulation niche variation

    EPA Science Inventory

    Background/Question/Methods The science of stable isotope mixing models has tended towards the development of modeling products (e.g. IsoSource, MixSIR, SIAR), where methodological advances or syntheses of the current state of the art are published in parity with software packa...

  13. Influence of condensate evaporation on water vapor and its stable isotopes in a GCM

    E-print Network

    Influence of condensate evaporation on water vapor and its stable isotopes in a GCM Jonathon S May 2009; published 17 June 2009. [1] The direct effect of condensate evaporation on atmospheric water. S., A. H. Sobel, and G. A. Schmidt (2009), Influence of condensate evaporation on water vapor

  14. APPLICATION OF STABLE CARBON AND HYDROGEN ISOTOPIC TECHNIQUES FOR MONITORING BIODEGRADATION OF MTBE IN THE FIELD

    EPA Science Inventory

    A significant challenge in environmental studies is to determine the onset and extent of MTBE bioremediation at an affected site, which may involve indirect approaches such as microcosm verification of microbial activities at a given site. Stable isotopic fractionation is cha...

  15. USING WINTER FLOUNDER GROWTH RATES AND STABLE ISOTOPES TO ASSESS HABITAT QUALITY

    EPA Science Inventory

    We used winter flounder growth rates and stable isotopes to assess habitat quality across an anthropogenic gradient in Narragansett Bay, Rhode Island. Cages (1 m2) were placed in the Providence River which had the highest nutrient concentrations and greatest development, Prudence...

  16. Constraining diamond metasomatic growth using C-and N-stable isotopes: examples from Namibia

    E-print Network

    Cartigny, Pierre

    Constraining diamond metasomatic growth using C- and N-stable isotopes: examples from Namibia-aggregation states for alluvial diamonds of known paragenesis from placers along the Namibian coast. The sample set includes diamonds with typical peridotitic and eclogitic inclusions and the recently reported

  17. Determining age and growth of abalone using stable oxygen isotopes: a tool for fisheries management

    Microsoft Academic Search

    L. J. Gurney; C. Mundy; M. C. Porteus

    2005-01-01

    Concerns of inaccuracy or bias associated with current techniques used to obtain age and growth data for abalone (age from shell layers, growth from tag-recapture, modal progression) have prompted consideration of alternative techniques to obtain data to ensure sustainable management of abalone fisheries. Stable oxygen isotopes have been used in many studies of molluscan age and growth, but to date

  18. Module 5: Applications of Stable Isotope Analyses: Data Interpretation and Data Quality Issues

    EPA Science Inventory

    When organic contaminants such as benzene, TCE or MTBE are degraded, the ratio of the stable isotopes of carbon in the organic contaminants will often change in a predictable fashion. In the last ten years, advances in analytical chemistry have made it possible to measure these ...

  19. Using Stable Isotopes to Understand Degradation of Organic Contaminants in Ground Water

    EPA Science Inventory

    Stable isotopes are a powerful tool to understand biodegradation. However, there are two interactions that can substantially confuse the interpretation of CSIR data: heterogeneity in flow paths in the aquifer and proximity to NAPL or other source of contamination to ground wate...

  20. Sea surface temperature control on the stable isotopic composition of rainfall in Panama

    E-print Network

    Lachniet, Matthew S.

    Sea surface temperature control on the stable isotopic composition of rainfall in Panama Matthew S investigated. Analysis of a 30-year time series of d18 Orain in Panama was used to test the hypothesis that d18) in the bordering tropical oceans. The results show that d18 Orain values in Panama are positively (negatively

  1. Southern Ocean control of silicon stable isotope distribution in the deep Atlantic Ocean

    E-print Network

    Paris-Sud XI, Université de

    Southern Ocean control of silicon stable isotope distribution in the deep Atlantic Ocean Gregory F distribution in the deep Atlantic Ocean from Denmark Strait to Drake Passage, documenting strong meridional sources of deep and bottom waters in the Atlantic Ocean: waters of North Atlantic and Nordic origin carry

  2. Experimental Evaluation of Stable Isotope Fractionation in Fish Muscle and Otoliths

    EPA Science Inventory

    We investigated an unresolved question in the use of stable isotopes to determine diet and trophic position of fish using both muscle and otoliths. We determined: i) the degree of fractionation of d13C and d15N between diet and muscle, and assessed if fractionation was consistent...

  3. Determination of confidence intervals of metabolic fluxes estimated from stable isotope measurements

    Microsoft Academic Search

    Maciek R. Antoniewicz; Joanne K. Kelleher; Gregory Stephanopoulos

    2006-01-01

    Metabolic fluxes, estimated from stable isotope studies, provide a key to quantifying physiology in fields ranging from metabolic engineering to the analysis of human metabolic diseases. A serious drawback of the flux estimation method in current use is that it does not produce confidence limits for the estimated fluxes. Without this information it is difficult to interpret flux results and

  4. Mucus: A new tissue fraction for rapid determination of fish diet switching using stable isotope analysis

    EPA Science Inventory

    Stable isotope analysis of diet switching by fishes often is hampered by slow turnover rates of the tissues analyzed (usually muscle or fins). We examined epidermal mucus as a potentially faster turnover ?tissue? that might provide a more rapid assessment of diet switching. In a ...

  5. NITROGEN STABLE ISOTOPE RATIOS IN SPOROCARPS OF ECTOMYCORRHIZAL FUNGI: INFLUENCE OF PHYLOGENETIC AND ENVIRONMENTAL FACTORS

    EPA Science Inventory

    It has been suggested that nitrogen stable isotope ratios (expressed as delta 15-N) of fungus sporocarps, in conjunction with delta 15-N data from other ecosystem compartments, can be used to elucidate key processes in forest N-cycling. Although results of previous studies genera...

  6. Insights from quantitative metaproteomics and protein-stable isotope probing into microbial ecology.

    PubMed

    von Bergen, Martin; Jehmlich, Nico; Taubert, Martin; Vogt, Carsten; Bastida, Felipe; Herbst, Florian-Alexander; Schmidt, Frank; Richnow, Hans-Hermann; Seifert, Jana

    2013-10-01

    The recent development of metaproteomics has enabled the direct identification and quantification of expressed proteins from microbial communities in situ, without the need for microbial enrichment. This became possible by (1) significant increases in quality and quantity of metagenome data and by improvements of (2) accuracy and (3) sensitivity of modern mass spectrometers (MS). The identification of physiologically relevant enzymes can help to understand the role of specific species within a community or an ecological niche. Beside identification, relative and absolute quantitation is also crucial. We will review label-free and label-based methods of quantitation in MS-based proteome analysis and the contribution of quantitative proteome data to microbial ecology. Additionally, approaches of protein-based stable isotope probing (protein-SIP) for deciphering community structures are reviewed. Information on the species-specific metabolic activity can be obtained when substrates or nutrients are labeled with stable isotopes in a protein-SIP approach. The stable isotopes ((13)C, (15)N, (36)S) are incorporated into proteins and the rate of incorporation can be used for assessing the metabolic activity of the corresponding species. We will focus on the relevance of the metabolic and phylogenetic information retrieved with protein-SIP studies and for detecting and quantifying the carbon flux within microbial consortia. Furthermore, the combination of protein-SIP with established tools in microbial ecology such as other stable isotope probing techniques are discussed. PMID:23677009

  7. Insights from quantitative metaproteomics and protein-stable isotope probing into microbial ecology

    PubMed Central

    von Bergen, Martin; Jehmlich, Nico; Taubert, Martin; Vogt, Carsten; Bastida, Felipe; Herbst, Florian-Alexander; Schmidt, Frank; Richnow, Hans-Hermann; Seifert, Jana

    2013-01-01

    The recent development of metaproteomics has enabled the direct identification and quantification of expressed proteins from microbial communities in situ, without the need for microbial enrichment. This became possible by (1) significant increases in quality and quantity of metagenome data and by improvements of (2) accuracy and (3) sensitivity of modern mass spectrometers (MS). The identification of physiologically relevant enzymes can help to understand the role of specific species within a community or an ecological niche. Beside identification, relative and absolute quantitation is also crucial. We will review label-free and label-based methods of quantitation in MS-based proteome analysis and the contribution of quantitative proteome data to microbial ecology. Additionally, approaches of protein-based stable isotope probing (protein-SIP) for deciphering community structures are reviewed. Information on the species-specific metabolic activity can be obtained when substrates or nutrients are labeled with stable isotopes in a protein-SIP approach. The stable isotopes (13C, 15N, 36S) are incorporated into proteins and the rate of incorporation can be used for assessing the metabolic activity of the corresponding species. We will focus on the relevance of the metabolic and phylogenetic information retrieved with protein-SIP studies and for detecting and quantifying the carbon flux within microbial consortia. Furthermore, the combination of protein-SIP with established tools in microbial ecology such as other stable isotope probing techniques are discussed. PMID:23677009

  8. TESTING THE USE OF STABLE ISOTOPES TO IDENTIFY FOOD WEB LINKS IN FRESHWATER RIVERINE COASTAL WETLANDS

    EPA Science Inventory

    Twenty riverine wetlands were sampled along the shores of Lake Michigan in 2001 as part of a Regional Environmental Monitoring and Assessment Program for coastal wetlands. Fish, invertebrates, periphyton, seston, and macrophytes were collected for N15 and C13 stable isotope analy...

  9. Stable carbon isotopic compositions of bacterial fatty acids in a seagrass dominated system

    E-print Network

    Jones, Walter Brian

    2001-01-01

    remineralized by the bacterial community has yet to be quantified (Jahnke and Craven 1995). Stable carbon isotopes (O' C) have been used as a tool to determine carbon sources for by meio- and macrofauna in seagrass beds (Riera er al. 1999, Moncreiff...

  10. Stable Isotope Ecology and Palaeodiet in the Lake Baikal Region of Siberia

    Microsoft Academic Search

    Andrzej Weber

    1999-01-01

    Human and non-human faunal bone from the Neolithic and Early Bronze Age periods of Cis-Baikal were analysed for stable isotopes of carbon and nitrogen in order to study regional and temporal variation in diet and subsistence. Both prehistoric and modern faunal species were analysed with all fish from the modern context. Results indicate that regional variation is greater than temporal

  11. Stable isotope analyses of the pelagic food web in Lake Baikal

    Microsoft Academic Search

    Koichi Yoshii; Natalia G. Melnik; Oleg A. Timoshkin; Nina A. Bondarenko; Pavel N. Anoshko; Takahito Yoshioka; Eitaro Wada

    1999-01-01

    Stable isotope ratios of various organisms were analyzed to elucidate food web structure in the pelagic zone of Lake Baikal. The pelagic food web of Lake Baikal is simple and consists of five major ecological groups: phyto- plankton (Aulacoseira baicalensis), mesozooplankton (Epischura baicalensis), macrozooplankton amphipod (Ma- crohectopus branickii), fish (Coregonus autumnalis migratoriusand four species of cottoid fishes), and seal (Phoca

  12. Identification of Methane, Ethane, and Propane Oxidizing Bacteria at Marine Hydrocarbon Seeps by Stable Isotope Probing

    Microsoft Academic Search

    M. Redmond; H. Ding; M. W. Friedrich; D. L. Valentine

    2008-01-01

    Hydrocarbon seeps emit substantial amounts of oil and natural gas into the marine environment, where they can be oxidized by microorganisms in the sediment and water column. Here, we used stable isotope probing of DNA and lipid biomarkers to identify the microorganisms actively consuming 13C-labeled natural gas compounds in seep sediment samples. Surface sediment was collected from the Coal Oil

  13. Revised folate content of foods determined by stable isotope dilution assays

    Microsoft Academic Search

    Michael Rychlik

    2004-01-01

    Stable isotope dilution assays were applied to quantify folates in several vegetables, orange juice, meat, liver, bread, and rice. The results were compared to data in the literature and in food data bases revealing significantly lower folate contents in broccoli and bread.Applying the new folate values to the Bavarian Food Intake Survey of 1995 resulted in a reduced daily intake

  14. Stable hydrogen and oxygen isotope ratios of bottled waters of the world

    Microsoft Academic Search

    Gabriel J. Bowen; David A. Winter; Howard J. Spero; Robert A. Zierenberg; Mathew D. Reeder; Thure E. Cerling; James R. Ehleringer

    2005-01-01

    Bottled and packaged waters are an increasingly significant component of the human diet. These products are regulated at the regional, national, and international levels, and determining the authenticity of marketing and labeling claims represents a challenge to regulatory agencies. Here, we present a dataset of stable isotope ratios for bottled waters sampled worldwide, and con- sider potential applications of such

  15. Best practices for use of stable isotope mixing models in food-web studies

    EPA Science Inventory

    Stable isotope mixing models are increasingly used to quantify contributions of resources to consumers. While potentially powerful tools, these mixing models have the potential to be misused, abused, and misinterpreted. Here we draw on our collective experiences to address the qu...

  16. Stable hydrogen isotopes of bone collagen in palaeodietary and palaeoenvironmental reconstruction

    Microsoft Academic Search

    L. M. Reynard; R. E. M. Hedges

    2008-01-01

    The stable hydrogen isotope ratios (?D) of bone collagen in archaeological human and animal samples demonstrate a trophic level effect, with increasing ?D from herbivores to omnivores to humans, in steps of 10–30‰. In addition the archaeological sites studied (Yarnton, Eton Rowing Lake, Danebury Environs–Suddern Farm, and Windmill Hill in the UK, Balatonszárszó in Hungary, and Huari in Peru) demonstrate

  17. Environmental changes o¡ North Iceland during the deglaciation and the Holocene: foraminifera, diatoms and stable isotopes

    Microsoft Academic Search

    K. L. Knudsen; H. Jiang; E. Jansen; J. Eir; J. Heinemeier; M.-S. Seidenkrantz

    A combined study of foraminifera, diatoms and stable isotopes in marine sediments off North Iceland records major changes in sea surface conditions since about 15 800 cal years (yr) BP. Results are presented from two gravity cores obtained at about 400 m water depth from two separate sedimentary basins on each side of the submarine Kolbeinsey Ridge. The chronology of

  18. Environmental changes off North Iceland during the deglaciation and the Holocene: foraminifera, diatoms and stable isotopes

    Microsoft Academic Search

    K. L Knudsen; H Jiang; E Jansen; J Eir??ksson; J Heinemeier; M.-S Seidenkrantz

    2004-01-01

    A combined study of foraminifera, diatoms and stable isotopes in marine sediments off North Iceland records major changes in sea surface conditions since about 15?800 cal years (yr) BP. Results are presented from two gravity cores obtained at about 400 m water depth from two separate sedimentary basins on each side of the submarine Kolbeinsey Ridge. The chronology of the

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

    Microsoft Academic Search

    Michael J. S. Tevesz; Alison L. Spongberg; Jonathan A. Fuller

    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

  20. Interpretation of denitrification and stable isotope fractionation in a heterogeneous aquifer using backward particle tracking simulation

    Microsoft Academic Search

    C. T. Green; B. A. Bekins; S. P. Phillips; J. Bohlke

    2008-01-01

    The mixing of groundwaters due to physical heterogeneity can complicate the inference of reactive transport characteristics from sample concentrations. This influence, however, has not been investigated systematically in heterogeneous aquifers. In this study, random walk particle tracking was used to evaluate the effects of mixing on inferred reaction rates and stable isotope fractionations. For a study site including a 1-km

  1. Tracing the pathways of Neotropical migratory shorebirds using stable isotopes: A pilot study

    Microsoft Academic Search

    A. Farmer; R. Rye; G. Landis; C. Kester; I. Ridley

    2003-01-01

    We evaluated the potential use of stable isotopes to establish linkages between the wintering grounds and the breeding grounds of the Pectoral Sandpiper (Calidris melanotos), the White-rumped Sandpiper (Calidris fuscicollis), the Baird's Sandpiper (Calidris bairdii), and other Neotropical migratory shorebird species (e.g., Tringa spp.). These species molt their flight feathers on the wintering grounds and hence their flight feathers carry

  2. Using Stable Isotope Analyses to Identify Allochthonous Inputs to Lake Naivasha Mediated via the Hippopotamus Gut

    Microsoft Academic Search

    J. Grey; D. M. Harper

    2002-01-01

    The hippopotamus grazes nocturnally on land and resides in water during the day. Much of the ingested material must therefore be defecated directly into the aquatic system and can thus be considered an allochthonous resource available to aquatic consumers. The utility of stable isotope analyses of carbon and nitrogen to distinguish hippo faecal matter from other potential basal resources was

  3. IDENTIFICATION OF 2,4-D DEGRADING SOIL MICROORGANISMS WITH STABLE ISOTOPE PROBING [ABSTRACT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable isotope probing (SIP) is a recently developed technique allowing function to be linked with identity without the need to isolate the bacteria involved. With this technique we investigated the microorganisms responsible for degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2, 4-D) i...

  4. Dietary segregation between two cohabiting species of sparrows revealed with stable isotope analysis

    E-print Network

    analysis J.M. Hipfner, B. Addison, and M.R. Charette Abstract: Fox Sparrows (Passerella iliaca (Merrem, Melospiza melodia, Passerella iliaca, Song Sparrow, stable isotopes. Résumé : Les bruants fauves (Passerella-clés : cohabitation, ségrégation alimentaire, bruant fauve, Melospiza melodia, Passerella iliaca, bruant chanteur

  5. Research review paper Stable isotope probing in the metagenomics era: A bridge towards

    E-print Network

    bioremediation Ondrej Uhlik a , Mary-Cathrine Leewis b , Michal Strejcek a , Lucie Musilova a , Martina Mackova a: Bioremediation Biodegradation Stable isotope probing Metagenomics Sequence-based screening Function Microbial biodegradation and biotransformation reactions are essential to most bioremediation processes, yet

  6. Evapotranspiration components determined by stable isotope, sap flow and eddy covariance techniques

    Microsoft Academic Search

    D. G. Williams; W. Cable; K. Hultine; J. C. B. Hoedjes; E. A. Yepez; V. Simonneaux; S. Er-Raki; G. Boulet; H. A. R. de Bruin; A. Chehbouni; O. K. Hartogensis; F. Timouk

    2004-01-01

    Understanding and modeling water exchange in arid and semiarid ecosystems is complicated by the very heterogeneous distribution of vegetation and moisture inputs, and the difficulty of measuring and validating component fluxes at a common scale. We combined eddy covariance (EC), sap flow, and stable isotope techniques to investigate the responses of transpiration and soil evaporation to an irrigation event in

  7. UNiquant, a Program for Quantitative Proteomics Analysis Using Stable Isotope Labeling

    Microsoft Academic Search

    Xin Huang; Aleksey V. Tolmachev; Yulei Shen; Miao Liu; Lin Huang; Zhixin Zhang; Gordon A. Anderson; Richard D. Smith; Wing C. Chan; Steven Hinrichs; Kai Fu; Shi-Jian Ding

    2011-01-01

    We present UNiquant, a new software program for analyzing stable isotope labeling (SIL) based quantitative proteomics data. UNiquant surpassed the performance of two other platforms, MaxQuant and Mascot Distiller, using complex proteome mixtures having either known or unknown heavy\\/light ratios. UNiquant is compatible with a broad spectrum of search engines and SIL methods, providing outstanding peptide pair identification and accurate

  8. BEHAVIORAL ECOLOGY -ORIGINAL PAPER Yolk carotenoids and stable isotopes reveal links among

    E-print Network

    BEHAVIORAL ECOLOGY - ORIGINAL PAPER Yolk carotenoids and stable isotopes reveal links among in Rights of Canada 2010 Abstract Nutrients that are limited in availability, such as carotenoids that affect the capacity of female birds to meet their carotenoid requirements are poorly under- stood. We

  9. You Are What You Eat: Stable Isotope Ecology of Owl Diets in Alberta, Canada

    Microsoft Academic Search

    Jason M. Duxbury; Geoffrey L. Holroyd

    Stable isotope ratio analysis (SIRA) was used to analyze the trophic level of the diets of three owl species: Barred Owl (Strix varia), Northern Hawk Owl (Surnia ulula) and Great Horned Owl (Bubo virginianus). Barred Owl and Northern Hawk Owl had diets from a similar trophic level. Both the Barred Owl and Northern Hawk Owl had diets from trophic levels

  10. Identifying Energy Sources Supporting Coastal Fish; Spatial Differences Revealed by Stable Isotope Ratios

    EPA Science Inventory

    The goal of our research is to identify energy inputs that support production of young fishes in coastal wetland ecosystem food webs using stable isotopes. The data demonstrate that strong spatial heterogeneity exists in this food web, implying that the energy sources supporting...

  11. Stable isotope niche differentiation in sticklebacks with symmetric and asymmetric pectoral fins

    E-print Network

    Reimchen, Thomas E.

    , but controversially, viewed as an indicator of fitness and a target of selection. In the brook stickleback, Culaea inconstans (Kirtland), FA of the pectoral fins, which are the main source of propulsion, is inversely the foraging behaviour of C. inconstans and that stable isotope analyses of individual phenotypes provides

  12. SOURCE AGGREGATION IN STABLE ISOTOPE MIXING MODELS: LUMP IT OR LEAVE IT?

    EPA Science Inventory

    A common situation when stable isotope mixing models are used to estimate source contributions to a mixture is that there are too many sources to allow a unique solution. To resolve this problem one option is to combine sources with similar signatures such that the number of sou...

  13. Stable isotope chronology and climate signal calibration in neotropical montane cloud forest trees

    Microsoft Academic Search

    K. J. Anchukaitis; M. N. Evans; N. T. Wheelwright; D. P. Schrag

    2008-01-01

    Tropical montane cloud forests are ecosystems intrinsically linked to a narrow range of geographic and meteorological conditions, making them potentially sensitive to small changes in precipitation or temperature. We investigate the potential application of stable isotope analysis to cloud forest dendroclimatology at Monteverde in Costa Rica in order to be able to extract both chronological and paleoclimate information from trees

  14. Stable carbon isotopes as an indicator of petroleum biodegradation in estuarine sediments 

    E-print Network

    Hesse, Deborah Louise

    1994-01-01

    An investigation into the use of stable carbon isotopes (513C) as tracers of biodegradation of petroleum in estuarine sediments was performed. This technique uses the 813C of respired C02 as an indicator of the organic matter being degraded...

  15. Analyses of the stable isotopic record for carbon, nitrogen and sulphur have suggested

    E-print Network

    Falkowski, Paul G.

    Analyses of the stable isotopic record for carbon, nitrogen and sulphur have suggested that, over principle holds for marine prokaryotes remains to be seen, because the spatial and temporal distribution and ocean environmental structure We first consider some of the basic concepts of the oceanic environment

  16. From the Cover: Carbon and nitrogen stable isotopes in fast food: Signatures of corn and confinement

    Microsoft Academic Search

    A. Hope Jahren; Rebecca A. Kraft

    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

  17. Contribution of Allochthonous Carbon to American Shad Production in the Mattaponi River, Virginia, Using Stable Isotopes

    EPA Science Inventory

    Our objective was to quantify the contribution of autochthonous, locally-produced phytoplankton, and allochthonous, terrestrial-derived organic matter (OM) to the production of young-of-year (YOY) American shad using stable isotopes...The results suggest an important link between...

  18. Diet of spotted bats (Euderma maculatum) in Arizona as indicated by fecal analysis and stable isotopes

    EPA Science Inventory

    We assessed diet of spotted bats (Euderma maculatum (J.A. Allen, 1891)) by visual analysis of bat feces and stable carbon (d13C) and nitrogen (d15N) isotope analysis of bat feces, wing, hair, and insect prey. We collected 33 fecal samples from spotted bats and trapped 3755 insect...

  19. Comparing trophic position of stream fishes using stable isotope and gut contents analyses

    EPA Science Inventory

    Stable isotope analysis (SIA) and gut content analysis (GCA) are commonly used in food web studies, but few studies analyze these data in concert. We used SIA and GCA to identify diets and trophic position (TP) of six stream fishes and to compare TP estimates between methods. Ord...

  20. Analysis of stable isotopes in fish mucus during a controlled diet switch

    EPA Science Inventory

    We have used a controlled diet switch in steelhead trout (Oncorhynchus mykiss) at the Oregon Hatchery Research Center to study the time rates of changes in stable isotopes of carbon and nitrogen (¿13C and ¿15N) in epidermal mucus, a rapidly responding ?tissue.? Because of the ra...