Sample records for compound-specific stable isotopes

  1. Microbial degradation of alpha-cypermethrin in soil by compound-specific stable isotope analysis. (United States)

    Xu, Zemin; Shen, Xiaoli; Zhang, Xi-Chang; Liu, Weiping; Yang, Fangxing


    To assess microbial degradation of alpha-cypermethrin in soil, attenuation of alpha-cypermethrin was investigated by compound-specific stable isotope analysis. The variations of the residual concentrations and stable carbon isotope ratios of alpha-cypermethrin were detected in unsterilized and sterilized soils spiked with alpha-cypermethrin. After an 80 days' incubation, the concentrations of alpha-cypermethrin decreased to 0.47 and 3.41 mg/kg in the unsterilized soils spiked with 2 and 10 mg/kg, while those decreased to 1.43 and 6.61 mg/kg in the sterilized soils. Meanwhile, the carbon isotope ratios shifted to -29.14 ± 0.22‰ and -29.86 ± 0.33‰ in the unsterilized soils spiked with 2 and 10 mg/kg, respectively. The results revealed that microbial degradation contributed to the attenuation of alpha-cypermethrin and induced the carbon isotope fractionation. In order to quantitatively assess microbial degradation, a relationship between carbon isotope ratios and residual concentrations of alpha-cypermethrin was established according to Rayleigh equation. An enrichment factor, ϵ = -1.87‰ was obtained, which can be employed to assess microbial degradation of alpha-cypermethrin. The significant carbon isotope fractionation during microbial degradation suggests that CSIA is a proper approach to qualitatively detect and quantitatively assess the biodegradation during attenuation process of alpha-cypermethrin in the field. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Comparing compound-specific and bulk stable nitrogen isotope trophic discrimination factors across multiple freshwater fish species and diets (United States)

    The use of nitrogen stable isotopes for estimation of animal trophic position has become an indispensable approach in food web ecology. Compound-specific isotope analysis of amino acids is a new approach for estimating trophic position that may overcome key issues associated with nitrogen stable iso...

  3. Assessing the functional diversity of herbivorous reef fishes using a compound-specific stable isotope approach

    KAUST Repository

    Tietbohl, Matthew


    Herbivorous coral reef fishes play an important role in helping to structure their environment directly by consuming algae and indirectly by promoting coral health and growth. These fishes are generally separated into three broad groups: browsers, grazers, and excavators/scrapers, with these groupings often thought to have a fixed general function and all fishes within a group thought to have similar ecological roles. This categorization assumes a high level of functional redundancy within herbivorous fishes. However, recent evidence questions the use of this broad classification scheme, and posits that there may actually be more resource partitioning within these functional groupings. Here, I use a compound-specific stable isotope approach (CSIA) to show there appears to be a greater diversity of functional roles than previously assumed within broad functional groups. The δ13C signatures from essential amino acids of reef end-members (coral, macroalgae, detritus, and phytoplankton) and fish muscle were analyzed to investigate differences in resource use between fishes. Most end-members displayed clear isotopic differences, and most fishes within functional groups were dissimilar in their isotopic signature, implying differences in the resources they target. No grazers closely resembled each other isotopically, implying a much lower level of functional redundancy within this group; scraping parrotfish were also distinct from excavating parrotfish and to a lesser degree distinct between scrapers. This study highlights the potential of CSIA to help distinguish fine-scale ecological differences within other groups of reef organisms as well. These results question the utility of lumping nominally herbivorous fishes into broad groups with assumed similar roles. Given the apparent functional differences between nominally herbivorous reef fishes, it is important for managers to incorporate the diversity of functional roles these fish play.

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

    KAUST Repository

    McMahon, Kelton


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

  5. Direct compound-specific stable chlorine isotope analysis of organic compounds with quadrupole GC/MS using standard isotope bracketing. (United States)

    Aeppli, Christoph; Holmstrand, Henry; Andersson, Per; Gustafsson, Orjan


    A method has been developed for the direct determination of the stable chlorine isotope composition (delta(37)Cl) of organochlorines that eliminates sample preparation, achieves precision comparable to earlier techniques while improving the sensitivity, and makes use of benchtop gas chromatography-quadrupole mass spectrometry instruments (GCqMS). The method is based on the use of multiple injections (n = 8-10) of the sample, bracketed by a molecularly identical isotopic standard with known delta(37)Cl, determined using off-line thermal ionization mass spectrometry (TIMS). Mass traces of two isotopologues differing by one chlorine isotope were used to calculate delta(37)Cl values. Optimization of mass spectrometry and peak integration parameters as well as method validation was achieved using tetrachloroethene (PCE), p,p'-dichlorodiphenyltrichloroethane (DDT), and pentachlorophenol (PCP), spanning a delta(37)Cl range of -5.5 to +3.2 per thousand vs SMOC. Injecting 1.6-1100 pmol resulted in standard deviations (1sigma) of 0.6-1.3 per thousand, and the delta(37)Cl results agreed with values independently measured with TIMS. The method was tested by determining the Rayleigh fractionation during evaporation of pure liquid PCE, resulting in a chlorine isotopic enrichment factor of epsilon(Cl) = -1.1 +/- 0.4 per thousand. Furthermore, position-specific delta(37)Cl analysis based on analysis of DDT mass fragments was evaluated. The GCqMS-delta(37)Cl method offers a simplified yet sensitive approach for compound-specific chlorine isotope analysis.

  6. Compound-Specific Stable Isotope Fractionation of Pesticides and Pharmaceuticals in a Mesoscale Aquifer Model. (United States)

    Schürner, Heide K V; Maier, Michael P; Eckert, Dominik; Brejcha, Ramona; Neumann, Claudia-Constanze; Stumpp, Christine; Cirpka, Olaf A; Elsner, Martin


    Compound-specific isotope analysis (CSIA) receives increasing interest for its ability to detect natural degradation of pesticides and pharmaceuticals. Despite recent laboratory studies, CSIA investigations of such micropollutants in the environment are still rare. To explore the certainty of information obtainable by CSIA in a near-environmental setting, a pulse of the pesticide bentazone, the pesticide metabolite 2,6-dichlorobenzamide (BAM), and the pharmaceuticals diclofenac and ibuprofen was released into a mesoscale aquifer with quasi-two-dimensional flow. Concentration breakthrough curves (BTC) of BAM and ibuprofen demonstrated neither degradation nor sorption. Bentazone was transformed but did not sorb significantly, whereas diclofenac showed both degradation and sorption. Carbon and nitrogen CSIA could be accomplished in similar concentrations as for "traditional" priority pollutants (low μg/L range), however, at the cost of uncertainties (0.4-0.5‰ (carbon), 1‰ (nitrogen)). Nonetheless, invariant carbon and nitrogen isotope values confirmed that BAM was neither degraded nor sorbed, while significant enrichment of (13)C and in particular (15)N corroborated transformation of diclofenac and bentazone. Retardation of diclofenac was reflected in additional (15)N sorption isotope effects, whereas isotope fractionation of transverse dispersion could not be identified. These results provide a benchmark on the performance of CSIA to monitor the reactivity of micropollutants in aquifers and may guide future efforts to accomplish CSIA at even lower concentrations (ng/L range).

  7. Degradation of sulfamethoxazole using ozone and chlorine dioxide - Compound-specific stable isotope analysis, transformation product analysis and mechanistic aspects. (United States)

    Willach, Sarah; Lutze, Holger V; Eckey, Kevin; Löppenberg, Katja; Lüling, Michelle; Terhalle, Jens; Wolbert, Jens-Benjamin; Jochmann, Maik A; Karst, Uwe; Schmidt, Torsten C


    The sulfonamide antibiotic sulfamethoxazole (SMX) is a widely detected micropollutant in surface and groundwaters. Oxidative treatment with e.g. ozone or chlorine dioxide is regularly applied for disinfection purposes at the same time exhibiting a high potential for removal of micropollutants. Especially for nitrogen containing compounds such as SMX, the related reaction mechanisms are largely unknown. In this study, we systematically investigated reaction stoichiometry, product formation and reaction mechanisms in reactions of SMX with ozone and chlorine dioxide. To this end, the neutral and anionic SMX species, which may occur at typical pH-values of water treatment were studied. Two moles of chlorine dioxide and approximately three moles of ozone were consumed per mole SMX degraded. Oxidation of SMX with ozone and chlorine dioxide leads in both cases to six major transformation products (TPs) as revealed by high-resolution mass spectrometry (HRMS). Tentatively formulated TP structures from other studies could partly be confirmed by compound-specific stable isotope analysis (CSIA). However, for one TP, a hydroxylated SMX, it was not possible by HRMS alone to identify whether hydroxylation occurred at the aromatic ring, as suggested in literature before, or at the anilinic nitrogen. By means of CSIA and an analytical standard it was possible to identify sulfamethoxazole hydroxylamine unequivocally as one of the TPs of the reaction of SMX with ozone as well as with chlorine dioxide. H-abstraction and electron transfer at the anilinic nitrogen are suggested as likely initial reactions of ozone and chlorine dioxide, respectively, leading to its formation. Oxidation of anionic SMX with ozone did not show any significant isotopic fractionation whereas the other reactions studied resulted in a significant carbon isotope fractionation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Compound-specific stable carbon isotopic signature of carbohydrate pyrolysis products from C3 and C4 plants. (United States)

    González-Pérez, José A; Jiménez-Morillo, Nicasio T; de la Rosa, José M; Almendros, Gonzalo; González-Vila, Francisco J


    Pyrolysis-compound specific isotopic analysis (Py-CSIA: Py-GC-(FID)-C-IRMS) is a relatively novel technique that allows on-line quantification of stable isotope proportions in chromatographically separated products released by pyrolysis. Validation of the Py-CSIA technique is compulsory for molecular traceability in basic and applied research. In this work, commercial sucrose from C4 (sugarcane) and C3 (sugarbeet) photosystem plants and admixtures were studied using analytical pyrolysis (Py-GC/MS), bulk δ(13)C IRMS and δ(13)C Py-CSIA. Major pyrolysis compounds were furfural (F), furfural-5-hydroxymethyl (HMF) and levoglucosan (LV). Bulk and main pyrolysis compound δ(13)C (‰) values were dependent on plant origin: C3 (F, -24.65 ± 0.89; HMF, -22.07 ± 0.41‰; LV, -21.74 ± 0.17‰) and C4 (F, -14.35 ± 0.89‰; HMF, -11.22 ± 0.54‰; LV, -11.44 ± 1.26‰). Significant regressions were obtained for δ(13)C of bulk and pyrolysis compounds in C3 and C4 admixtures. Furfural (F) was found (13)C depleted with respect to bulk and HMF and LV, indicating the incorporation of the light carbon atom in position 6 of carbohydrates in the furan ring after pyrolysis. This is the first detailed report on the δ(13)C signature of major pyrolytically generated carbohydrate-derived molecules. The information provided by Py-CSIA is valuable for identifying source marker compounds of use in food science/fraud detection or in environmental research. © 2015 Society of Chemical Industry.

  9. Apportioning sources of organic matter in streambed sediments: An integrated molecular and compound-specific stable isotope approach

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Richard J., E-mail: [School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ (United Kingdom); Pedentchouk, Nikolai; Hiscock, Kevin M.; Disdle, Paul [School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ (United Kingdom); Krueger, Tobias [IRI THESys, Humboldt University, 10099 Berlin (Germany); Rawlins, Barry G. [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom)


    We present a novel application for quantitatively apportioning sources of organic matter in streambed sediments via a coupled molecular and compound-specific isotope analysis (CSIA) of long-chain leaf wax n-alkane biomarkers using a Bayesian mixing model. Leaf wax extracts of 13 plant species were collected from across two environments (aquatic and terrestrial) and four plant functional types (trees, herbaceous perennials, and C{sub 3} and C{sub 4} graminoids) from the agricultural River Wensum catchment, UK. Seven isotopic (δ{sup 13}C{sub 27}, δ{sup 13}C{sub 29}, δ{sup 13}C{sub 31}, δ{sup 13}C{sub 27–31}, δ{sup 2}H{sub 27}, δ{sup 2}H{sub 29}, and δ{sup 2}H{sub 27–29}) and two n-alkane ratio (average chain length (ACL), carbon preference index (CPI)) fingerprints were derived, which successfully differentiated 93% of individual plant specimens by plant functional type. The δ{sup 2}H values were the strongest discriminators of plants originating from different functional groups, with trees (δ{sup 2}H{sub 27–29} = − 208‰ to − 164‰) and C{sub 3} graminoids (δ{sup 2}H{sub 27–29} = − 259‰ to − 221‰) providing the largest contrasts. The δ{sup 13}C values provided strong discrimination between C{sub 3} (δ{sup 13}C{sub 27–31} = − 37.5‰ to − 33.8‰) and C{sub 4} (δ{sup 13}C{sub 27–31} = − 23.5‰ to − 23.1‰) plants, but neither δ{sup 13}C nor δ{sup 2}H values could uniquely differentiate aquatic and terrestrial species, emphasizing a stronger plant physiological/biochemical rather than environmental control over isotopic differences. ACL and CPI complemented isotopic discrimination, with significantly longer chain lengths recorded for trees and terrestrial plants compared with herbaceous perennials and aquatic species, respectively. Application of a comprehensive Bayesian mixing model for 18 streambed sediments collected between September 2013 and March 2014 revealed considerable temporal variability in the

  10. Functional connectivity of coral reef fishes in a tropical seascape assessed by compound-specific stable isotope analyses

    KAUST Repository

    McMahon, Kelton W.


    The ecological integrity of tropical habitats, including mangroves, seagrass beds and coral reefs, is coming under increasing pressure from human activities. Many coral reef fish species are thought to use mangroves and seagrass beds as juvenile nurseries before migrating to coral reefs as adults. Identifying essential habitats and preserving functional linkages among these habitats is likely necessary to promote ecosystem health and sustainable fisheries on coral reefs. This necessitates quantitative assessment of functional connectivity among essential habitats at the seascape level. This thesis presents the development and first application of a method for tracking fish migration using amino acid (AA) δ13C analysis in otoliths. In a controlled feeding experiment with fish reared on isotopically distinct diets, we showed that essential AAs exhibited minimal trophic fractionation between consumer and diet, providing a δ13C record of the baseline isoscape. We explored the potential for geochemical signatures in otoliths of snapper to act as natural tags of residency in seagrass beds, mangroves and coral reefs in the Red Sea, Caribbean Sea and Eastern Pacific Ocean. The δ13C values of otolith essential AAs varied as a function of habitat type and provided a better tracer of residence in juvenile nursery habitats than conventional bulk stable isotope analyses (SIA). Using our otolith AA SIA approach, we quantified the relative contribution of coastal wetlands and reef habitats to Lutjanus ehrenbergii populations on coastal, shelf and oceanic coral reefs in the Red Sea. L. ehrenbergii made significant ontogenetic migrations, traveling more than 30 km from juvenile nurseries to coral reefs and across deep open water. Coastal wetlands were important nurseries for L. ehrenbergii; however, there was significant plasticity in L. ehrenbergii juvenile habitat requirements. Seascape configuration played an important role in determining the functional connectivity of L

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

    Energy Technology Data Exchange (ETDEWEB)

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


    Graphical abstract: -- Highlights: •For GCC–IRMS analysis, an approach avoiding impact of NO{sub 2} on δ{sup 13}C was demonstrated. •Carbon isotope fractionations during derivatizing reactions here were negligible. •Except some labile compounds, the overall bias of the method here was −0.21‰. •Even for the labile compounds, measurement biases ranged +1.2‰ to −1.4‰. •Real sample analysis demonstrates usefulness of the method for fractionation study. -- Abstract: We developed an analytical method for measuring compound-specific stable carbon isotope ratios (δ{sup 13}C) of phenols and nitrophenols in filter samples of particulate organic matter. The method was tested on 13 phenols derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), together with four nonphenolic compounds. The data obtained by our method required two specific corrections for the determination of valid δ{sup 13}C values: (1) for nitro compounds, the routine correction with use of m/z 46 for the contribution of {sup 12}C{sup 17}O{sup 16}O molecules) to m/z 45 was modified due to impact of NO{sub 2} on the m/z 46 trace, and (2) for the derivatized phenols, measured δ{sup 13}C values were corrected for the shift in δ{sup 13}C due to the addition of carbon atoms from the BSTFA moiety. Analysis of standard-spiked filters showed that overall there was a small compound-dependent bias in the δ{sup 13}C values: the average bias ± the standard error of the mean of −0.21 ± 0.1‰ for the standard compounds tested, except 3-methylcatechol, methylhydroquinone, 4-methyl-2-nitrophenol, and 2,6-dimethyl-4-nitrophenol, whereas the average biases ± the standard errors of the mean for those were +1.2 ± 0.3‰, +1.2 ± 0.2‰, −1.2 ± 0.2‰, and −1.4 ± 0.5‰, respectively, when the injected mass of a derivatized compound exceeded 15 ngC. In situations where such small biases and uncertainties are acceptable, the method described here could be used to obtain valuable

  12. Evaluation of the performance of high temperature conversion reactors for compound-specific oxygen stable isotope analysis. (United States)

    Hitzfeld, Kristina L; Gehre, Matthias; Richnow, Hans-Hermann


    In this study conversion conditions for oxygen gas chromatography high temperature conversion (HTC) isotope ratio mass spectrometry (IRMS) are characterised using qualitative mass spectrometry (IonTrap). It is shown that physical and chemical properties of a given reactor design impact HTC and thus the ability to accurately measure oxygen isotope ratios. Commercially available and custom-built tube-in-tube reactors were used to elucidate (i) by-product formation (carbon dioxide, water, small organic molecules), (ii) 2nd sources of oxygen (leakage, metal oxides, ceramic material), and (iii) required reactor conditions (conditioning, reduction, stability). The suitability of the available HTC approach for compound-specific isotope analysis of oxygen in volatile organic molecules like methyl tert-butyl ether is assessed. Main problems impeding accurate analysis are non-quantitative HTC and significant carbon dioxide by-product formation. An evaluation strategy combining mass spectrometric analysis of HTC products and IRMS (18)O/(16)O monitoring for future method development is proposed.

  13. Multi-element compound specific stable isotope analysis of volatile organic compounds at trace levels in groundwater samples (United States)

    Herrero-Martín, Sara; Nijenhuis, Ivonne; Schmidt, Marie; Wolfram, Diana; Richnow, Hans. H.; Gehre, Matthias


    Groundwater pollution remains one of the major environmental and health concerns. A thorough understanding of sources, sinks and transformation processes of groundwater contaminants is needed to improve risk management evaluation, and to design efficient remediation and water treatment strategies. Isotopic tools provide unique information for an in-depth understanding of the fate of organic chemicals in the environment. During the last decades compound specific isotope analysis (CSIA) of complex mixtures, using gas chromatography-isotope ratio mass spectrometry (GC-IRMS), has gained popularity for the characterization and risk assessment of hazardous waste sites and for isotope forensics of organic contaminants. Multi-element isotope fingerprinting of organic substances provides a more robust framework for interpretation than the isotope analysis of only one element. One major challenge for application of CSIA is the analysis of trace levels of organic compounds in environmental matrices. It is necessary to inject 1 nmol carbon or 8 nmol hydrogen on column, to obtain an accurate and precise measurement of the isotope ratios, which is between two and three orders of magnitude larger than the amount of compound needed for conventional analysis of compound concentrations. Therefore, efficient extraction and pre-concentration techniques have to be integrated with GC-IRMS. Further research is urgently needed in this field, to evaluate the potential of novel and environmental-friendly sample pre-treatment techniques for CSIA to lower the detection limits and extending environmental applications. In this study, the novel coupling of a headspace autosampler (HS) with a programmed temperature vaporizer (PTV), allowing large volume injection of headspace samples, is proposed to improve the sensitivity of CSIA. This automatic, fast and solvent free strategy provides a significant increase on the sensitivity of GC-based methods maintaining the simple headspace instrumentation

  14. Compound specific stable isotopes as probes for distinguishing the sources of biomolecules in terrestrial and extraterrestrial materials (United States)

    Engel, M. H.; Macko, S. A.


    Life on Earth consists of orderly arrangements of several key types of organic compounds (amino acids, sugars, fatty acids, nucleic bases) that are the building blocks of proteins, carbohydrates, lipids and nucleotides. Subsequent to death, macromolecules are commonly broken down to their molecular constituents or other similar scale components. Thus, in ancient terrestrial and extraterrestrial materials, it is far more likely to expect the presence of simple compounds such as amino acids rather than the proteins from which they were possibly derived. Given that amino acids, for example, are common components of all extinct and extant organisms, the challenge has been to develop methods for distinguishing their sources. Stable isotopes are powerful probes for determining the origins of organic matter. Amino acid constituents of all organisms on Earth exhibit characteristic stable isotope compositions owing to fractionations associated with their biosynthesis. These fractionations are distinct from those observed for amino acids formed by abiotic processes. Thus it should be possible to use isotopes as probes for determining whether amino acids in ancient rocks on Earth are biotic or abiotic, based on their relative isotopic compositions. Also, owing to differences in the isotope compositions of precursors, amino acids in extraterrestrial materials such as carbonaceous meteorites are moderately to substantially enriched in the heavy isotopes of C, N and H relative to terrestrial amino acids. Assuming that the isotope compositions of the gaseous components of, for example, the Martian atmosphere were distinct from Earth at such time when organic molecules may have formed, it should be possible to distinguish these components from terrestrial contaminants by determining their isotope compositions and/or those of their respective enantiomers. Also, if life as we know it existed on another planet such as Mars, fractionations characteristic of biosynthesis should be

  15. The CSSIAR v.1.00 Software: A new tool based on SIAR to assess soil redistribution using Compound Specific Stable Isotopes (United States)

    Sergio, de los Santos-Villalobos; Claudio, Bravo-Linares; dos Anjos Roberto, Meigikos; Renan, Cardoso; Max, Gibbs; Andrew, Swales; Lionel, Mabit; Gerd, Dercon

    Soil erosion is one of the biggest challenges for food production around the world. Many techniques have been used to evaluate and mitigate soil degradation. Nowadays isotopic techniques are becoming a powerful tool to assess soil apportionment. One of the innovative techniques used is the Compound Specific Stable Isotopes (CSSI) analysis, which has been used to track down sediments and specify their sources by the isotopic signature of δ13 C in specific fatty acids. The application of this technique on soil apportionment has been recently developed, however there is a lack of user-friendly Software for data processing and interpretation. The aim of this article is to introduce a new open source tool for working with data sets generated by the use of the CSSI technique to assess soil apportionment, called the CSSIARv1.00 Software

  16. The CSSIAR v.1.00 Software: A new tool based on SIAR to assess soil redistribution using Compound Specific Stable Isotopes

    Directory of Open Access Journals (Sweden)

    de los Santos-Villalobos Sergio


    Full Text Available Soil erosion is one of the biggest challenges for food production around the world. Many techniques have been used to evaluate and mitigate soil degradation. Nowadays isotopic techniques are becoming a powerful tool to assess soil apportionment. One of the innovative techniques used is the Compound Specific Stable Isotopes (CSSI analysis, which has been used to track down sediments and specify their sources by the isotopic signature of δ13C in specific fatty acids. The application of this technique on soil apportionment has been recently developed, however there is a lack of user-friendly Software for data processing and interpretation. The aim of this article is to introduce a new open source tool for working with data sets generated by the use of the CSSI technique to assess soil apportionment, called the CSSIARv1.00 Software

  17. Molecular Distributions and Compound-specific Stable Carbon Isotopic Compositions of Lipids in Wintertime Aerosols from Beijing (United States)

    Ren, L.; Fu, P.; He, Y.; Hou, J.; Chen, J.; Chandra Mouli, P.; Yele, S.; Wang, Z.


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

  18. Compound-specific 15N stable isotope probing of N assimilation by the soil microbial biomass: a new methodological paradigm in soil N cycling (United States)

    Charteris, A. F.; Knowles, T. D. J.; Michaelides, K.; Evershed, R. P.


    A compound-specific nitrogen-15 stable isotope probing (15N-SIP) technique is described which allows investigation of the fate of inorganic- or organic-N amendments to soils. The technique uses gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) to determine the δ15N values of individual amino acids (AAs; determined as N-acetyl, O-isopropyl derivatives) as proxies of biomass protein production. The δ15N values are used together with AA concentrations to quantify N assimilation of 15N-labelled substrates by the soil microbial biomass. The utility of the approach is demonstrated through incubation experiments using inorganic 15N-labelled substrates ammonium (15NH4+) and nitrate (15NO3-) and an organic 15N-labelled substrate, glutamic acid (15N-Glu). Assimilation of all the applied substrates was undetectable based on bulk soil properties, i.e. % total N (% TN), bulk soil N isotope composition and AA concentrations, all of which remained relatively constant throughout the incubation experiments. In contrast, compound-specific AA δ15N values were highly sensitive to N assimilation, providing qualitative and quantitative insights into the cycling and fate of the applied 15N-labelled substrates. The utility of this 15N-AA-SIP technique is considered in relation to other currently available methods for investigating the microbially-mediated assimilation of nitrogenous substrates into the soil organic N pool. This approach will be generally applicable to the study of N cycling in any soil, or indeed, in any complex ecosystem.

  19. Sources of variability in fatty acid (FA) biomarkers in the application of compound-specific stable isotopes (CSSIs) to soil and sediment fingerprinting and tracing: A review

    Energy Technology Data Exchange (ETDEWEB)

    Reiffarth, D.G., E-mail: [Natural Resources and Environmental Studies Program, University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9 (Canada); Petticrew, E.L., E-mail: [Geography Program and Quesnel River Research Centre, University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9 (Canada); Owens, P.N., E-mail: [Environmental Science Program and Quesnel River Research Centre, University of Northern British Columbia, 3333 University Way, Prince George, BC, V2N 4Z9 (Canada); Lobb, D.A., E-mail: [Watershed Systems Research Program, University of Manitoba, 13 Freedman Crescent, Winnipeg, MB R3T 2N2 (Canada)


    Determining soil redistribution and sediment budgets in watersheds is often challenging. One of the methods for making such determinations employs soil and sediment fingerprinting techniques, using sediment properties such as geochemistry, fallout radionuclides, and mineral magnetism. These methods greatly improve the estimation of erosion and deposition within a watershed, but are limited when determining land use-based soil and sediment movement. Recently, compound-specific stable isotopes (CSSIs), which employ fatty acids naturally occurring in the vegetative cover of soils, offer the possibility of refining fingerprinting techniques based on land use, complementing other methods that are currently in use. The CSSI method has been met with some success; however, challenges still remain with respect to scale and resolution due to a potentially large degree of biological, environmental and analytical uncertainty. By better understanding the source of tracers used in CSSI work and the inherent biochemical variability in those tracers, improvement in sample design and tracer selection is possible. Furthermore, an understanding of environmental and analytical factors affecting the CSSI signal will lead to refinement of the approach and the ability to generate more robust data. This review focuses on sources of biological, environmental and analytical variability in applying CSSI to soil and sediment fingerprinting, and presents recommendations based on past work and current research in this area for improving the CSSI technique. A recommendation, based on current information available in the literature, is to use very-long chain saturated fatty acids and to avoid the use of the ubiquitous saturated fatty acids, C{sub 16} and C{sub 18}. - Highlights: • Compound-specific stable isotopes (CSSIs) of carbon may be used as soil tracers. • The variables affecting CSSI data are: biological, environmental and analytical. • Understanding sources of variability will lead

  20. Direct photolysis of sulfamethoxazole using various irradiation sources and wavelength ranges - insights from degradation product analysis and compound-specific stable isotope analysis. (United States)

    Willach, Sarah; Lutze, Holger Volker; Eckey, Kevin; Löppenberg, Katja; Lueling, Michelle; Wolbert, Jens-Benjamin; Kujawinski, Dorothea M; Jochmann, Maik A; Karst, Uwe; Schmidt, Torsten Claus


    The environmental micropollutant sulfamethoxazole (SMX) is susceptible to phototransformation by sunlight and UV-C light which is used for water disinfection. Depending on the environmental pH conditions SMX may be present as neutral or anionic species. This study systematically investigates the phototransformation of these two relevant SMX species using four different irradiation scenarios, i.e. a low, medium and high pressure Hg lamp and simulated sunlight. The observed phototransformation kinetics are complemented by data from compound-specific stable isotope and transformation product analysis using isotope-ratio and high-resolution mass spectrometry (HRMS). Observed phototransformation kinetics were faster for the neutral than for the anionic SMX species (from 3.4 (LP lamp) up to 6.6 (HP lamp) times). Furthermore, four phototransformation products (with m/z 189, 202, 242, and 260) were detected by HRMS that have not yet been described for direct photolysis of SMX. Isotopic fractionation occurred only if UV-B and UV-A wavelengths prevailed in the emitted irradiation and was most pronounced for the neutral species with simulated sunlight (εC = 4.8 ± 0.1 ‰). Phototransformation of SMX with UV-C light did not cause significant isotopic fractionation. Consequently, it was possible to differentiate sunlight and UV-C light induced phototransformation of SMX. Thus CSIA might be implemented to trace back waste water point sources or to assess natural attenuation of SMX by sunlight photolysis. In contrast to the wavelength range, pH-dependent speciation of SMX did hardly impact isotopic fractionation.

  1. Compound-specific stable isotope records of precipitation isotopes and paleotopographic evolution: Patterns of Cenozoic change in the Western U.S. (United States)

    Hren, M. T.


    The topography of an orogen reflects the complex interplay between processes that occur at depth in the crust and processes such as erosion and weathering that shape the surface landscape. Reconstructions of paleotopography are critical for evaluating geodynamic models and separating effects of climatic and tectonic change in terrestrial records. Stable isotope paleoaltimetry has proved to be an important tool for understanding changes in topography through time, however this approach is complicated by factors such as mixing of moisture sources, uncertainty over how uplift impacts air mass transport and resultant isotope hydrology, and debate over what some proxies actually record. Hydrogen isotopes of organic molecules provide a means of reconstructing isotopes of ambient water, but these data are also impacted by factors that affect biological processes and stomatal regulation. Despite the myriad factors that can impact isotope fractionation in plant waxes, a growing body of data show these molecules to be an important record of precipitation isotopes when coupled with data that relates to ecosystem type. This study will examine the distribution of hydrogen isotopes of higher plant waxes across the western U.S. at key intervals of the Cenozoic to provide a snapshot of long-wavelength changes to topography and moisture sources from the Eocene to recent. These data demonstrate the utility of biomarker isotopes as a paleohydrologic/paleotopographic proxy and point to long-standing high topography over much of western U.S. throughout the Cenozoic.

  2. All fats are not equal: Considerations when using fatty acid biomarkers in compound-specific stable isotope soil and sediment tracing (United States)

    Reiffarth, Dominic; Petticrew, Ellen; Owens, Philip; Lobb, David


    The development of cost-effective, convenient and reliable methods for tracing sediment movement will help establish water security. The use of compound-specific stable isotopes (CSSIs) has seen limited, small-scale applications, often in watersheds exhibiting exotic and highly diverse vegetation types. The CSSI tracing technique relies on the detection and transport of naturally occurring organics of plant origin (biomarkers); the biomarkers of interest are produced by flora, deposited on the soil and potentially mobilized along with soil particles. In part, the uniqueness of a biomarker is dependent on its biological pathway. As a plant fixes CO2-its primary source of carbon for building larger organic molecules-discrimination against the heavier 13C isotope leads to an enrichment of 12C. The more complex the biological pathway the biomarker has been subjected to, the more discrimination and unique isotopic signature the biomarker exhibits. Successfully implementing CSSI tracing requires recognizing: (i) factors contributing to the natural variability of the isotopic signature (ii) the suitability of a biomarker and (iii) factors affecting sensitivity during analysis. Considering the relatively low input of suitable organic biomarkers into the soil and degree of signal dispersion, care must be taken to isolate and correctly identify biomarkers, particularly where vegetation types show low variability and where long-range transport occurs. Research is currently being conducted in the Horsefly River (British Columbia, Canada) and South Tobacco Creek (Manitoba, Canada) watersheds; the research seeks to address some of these concerns, particularly in a temperate climate where exotic vegetation types are not common and variability is expected to be low.

  3. Compound Specific Stable Chlorine Isotopic Analysis of Volatile Aliphatic Compounds Using Gas Chromatography Hyphenated with Multiple Collector Inductively Coupled Plasma Mass Spectrometry. (United States)

    Horst, Axel; Renpenning, Julian; Richnow, Hans-Hermann; Gehre, Matthias


    Stable chlorine isotope analysis is increasingly used to characterize sources, transformation pathways, and sinks of organic aliphatic compounds, many of them being priority pollutants in groundwater and the atmosphere. A wider use of chlorine isotopes in environmental studies is still inhibited by limitations of the different analytical techniques such as high sample needs, offline preparation, confinement to few compounds and mediocre precision, respectively. Here we present a method for the δ37Cl determination in volatile aliphatic compounds using gas chromatography coupled with multiple-collector inductively coupled plasma mass spectrometry (GC-MC-ICPMS), which overcomes these limitations. The method was evaluated by using a suite of five previously offline characterized in-house standards and eight chlorinated methanes, ethanes, and ethenes. Other than in previous approaches using ICP methods for chlorine isotopes, isobaric interference of the 36ArH dimer with 37Cl was minimized by employing dry plasma conditions. Samples containing 2-3 nmol Cl injected on-column were sufficient to achieve a precision (σ) of 0.1 mUr (1 milliurey = 0.001 = 1‰) or better. Long-term reproducibility and accuracy was always better than 0.3 mUr if organics were analyzed in compound mixtures. Standardization is carried out by using a two-point calibration approach. Drift, even though very small in this study, is corrected by referencing versus an internal standard. The presented method offers a direct, universal, and compound-specific procedure to measure the δ37Cl of a wide array of organic compounds overcoming limitations of previous techniques with the benefits of high sensitivity and accuracy comparable to the best existing approaches.

  4. Direct Tracking and Compound-Specific Stable Isotope Analysis Identifies Dispersal Routes and Cryptic Latitudinal Trends in the Winter Distribution of Two Antarctic Penguin Species (United States)

    Polito, M. J.; Houghton, L. A.; Hinke, J.; Thorrold, S.


    Animal dispersal behaviors have both ecological and evolutionary significance. However, due to the logistical challenges of tracking animals in the Antarctic marine environment little is known about the winter dispersal and migration of Antarctic marine predators. We used a combination of direct tracking (Geolocation sensors; GLS) and compound-specific stable isotope analysis of carbon in essential amino acids (CSIA-AA) to describe the winter distribution of two wide-ranging marine predators, the Adélie penguin (Pygoscelis adeliae) and chinstrap penguin (P. antarctica) along the Antarctic Peninsula and Scotia Arc. GLS and CSIA-AA identified two general migration strategies, with animals overwintering to the east or west of the Antarctic Peninsula, with CSIA-AA also being able to discriminate between ice-free vs. pack-ice habitats. In addition, CSIA-AA provided the ability to assign non GLS-tracked chinstrap penguins from multiple breeding sites across the Scotia Arc to specific over-wintering areas. This provided a first ever, regional-scale analyses of the winter movements and distributions of the species and identified a cryptic latitudinal trend that would have been otherwise undetectable. Breeding colonies farther north were more likely to have individuals dispersing eastwards relative to colonies further south where most individual dispersed westwards, possibly due to a combination of proximity and competition avoidance. Finally we highlight how CSIA-AA approaches can be applied to other studies of the distribution and ecology of marine top predators.

  5. Compound-specific stable isotopes of organic compounds from lake sediments track recent environmental changes in an alpine ecosystem, Rocky Mountain National Park, Colorado (United States)

    Enders, S.K.; Pagani, M.; Pantoja, S.; Baron, J.S.; Wolfe, A.P.; Pedentchouk, N.; Nunez, L.


    Compound-specific nitrogen, carbon, and hydrogen isotope records from sediments of Sky Pond, an alpine lake in Rocky Mountain National Park (Colorado, United States of America), were used to evaluate factors contributing to changes in diatom assemblages and bulk organic nitrogen isotope records identified in lake sediments across Colorado, Wyoming, and southern Montana. Nitrogen isotopic records of purified algal chlorins indicate a substantial shift in nitrogen cycling in the region over the past ???60 yr. Temporal changes in the growth characteristics of algae, captured in carbon isotope records in and around Sky Pond, as well as a -60??? excursion in the hydrogen isotope composition of algal-derived palmitic acid, are coincident with changes in nitrogen cycling. The confluence of these trends is attributed to an increase in biologically available nitrogenous compounds caused by an expansion of anthropogenic influences and temporal changes in catchment hydrology and nutrient delivery associated with meltwater dynamics. ?? 2008, by the American Society of Limnology and Oceanography, Inc.

  6. Complementing approaches to demonstrate chlorinated solvent biodegradation in a complex pollution plume: Mass balance, PCR and compound-specific stable isotope analysis. (United States)

    Courbet, Christelle; Rivière, Agnès; Jeannottat, Simon; Rinaldi, Sandro; Hunkeler, Daniel; Bendjoudi, Hocine; de Marsily, Ghislain


    This work describes the use of different complementing methods (mass balance, polymerase chain reaction assays and compound-specific stable isotope analysis) to demonstrate the existence and effectiveness of biodegradation of chlorinated solvents in an alluvial aquifer. The solvent-contaminated site is an old chemical factory located in an alluvial plain in France. As most of the chlorinated contaminants currently found in the groundwater at this site were produced by local industries at various times in the past, it is not enough to analyze chlorinated solvent concentrations along a flow path to convincingly demonstrate biodegradation. Moreover, only a few data were initially available to characterize the geochemical conditions at this site, which were apparently complex at the source zone due to (i) the presence of a steady oxygen supply to the groundwater by irrigation canal losses and river infiltration and (ii) an alkaline pH higher than 10 due to former underground lime disposal. A demonstration of the existence of biodegradation processes was however required by the regulatory authority within a timeframe that did not allow a full geochemical characterization of such a complex site. Thus a combination of different fast methods was used to obtain a proof of the biodegradation occurrence. First, a mass balance analysis was performed which revealed the existence of a strong natural attenuation process (biodegradation, volatilization or dilution), despite the huge uncertainty on these calculations. Second, a good agreement was found between carbon isotopic measurements and PCR assays (based on 16S RNA gene sequences and functional genes), which clearly indicated reductive dechlorination of different hydrocarbons (Tetrachloroethene--PCE-, Trichloroethene--TCE-, 1,2-cisDichloroethene--cis-1,2-DCE-, 1,2-transDichloroethene-trans--1,2-DCE-, 1,1-Dichloroethene--1,1-DCE-, and Vinyl Chloride--VC) to ethene. According to these carbon isotope measurements, although TCE

  7. Metabolism of Seriola lalandi during Starvation as Revealed by Fatty Acid Analysis and Compound-Specific Analysis of Stable Isotopes within Amino Acids.

    Directory of Open Access Journals (Sweden)

    Fernando Barreto-Curiel

    Full Text Available Fish starvation is defined as food deprivation for a long period of time, such that physiological processes become confined to basal metabolism. Starvation provides insights in physiological processes without interference from unknown factors in digestion and nutrient absorption occurring in fed state. Juveniles of amberjack Seriola lalandi were isotopically equilibrated to a formulated diet for 60 days. One treatment consisted of fish that continued to be fed and fish in the other treatment were not fed for 35 days. The isotopic signatures prior to the beginning of and after the starvation period, for fish in the starvation and control treatments, were analysed for lipid content, fatty acid composition and isotopic analysis of bulk (EA-IRMS and of amino acids (compound specific isotope analysis, CSIA. There were three replicates for the starvation group. Fatty acid content in muscle and liver tissue before and after starvation was determined to calculate percent change. Results showed that crude lipid was the most used source of energy in most cases; the PUFAs and LC-PUFAs were highly conserved. According to the protein signature in bulk (δ15N and per amino acid (δ13C and δ15N, in muscle tissue, protein synthesis did not appear to occur substantially during starvation, whereas in liver, increases in δ13C and δ15N indicate that protein turnover occurred, probably for metabolic routing to energy-yielding processes. As a result, isotopic values of δ15N in muscle tissue do not change, whereas CSIA net change occurred in the liver tissue. During the study period of 35 days, muscle protein was largely conserved, being neither replenished from amino acid pools in the plasma and liver nor catabolized.

  8. Tracing fresh assimilates through Larix decidua exposed to elevated CO₂ and soil warming at the alpine treeline using compound-specific stable isotope analysis. (United States)

    Streit, Kathrin; Rinne, Katja T; Hagedorn, Frank; Dawes, Melissa A; Saurer, Matthias; Hoch, Günter; Werner, Roland A; Buchmann, Nina; Siegwolf, Rolf T W


    How will carbon source-sink relations of 35-yr-old larch trees (Larix decidua) at the alpine treeline respond to changes in atmospheric CO(2) and climate? We evaluated the effects of previously elevated CO(2) concentrations (9 yr, 580 ppm, ended the previous season) and ongoing soil warming (4 yr, + 4°C). Larch branches were pulse labeled (50 at% (13)CO(2)) in July 2010 to trace fresh assimilates through tissues (buds, needles, bark and wood) and non-structural carbon compounds (NCC; starch, lipids, individual sugars) using compound-specific isotope analysis. Nine years of elevated CO(2) did not lead to increased NCC concentrations, nor did soil warming increase NCC transfer velocities. By contrast, we found slower transfer velocities and higher NCC concentrations than reported in the literature for lowland larch. As a result of low dilution with older carbon, sucrose and glucose showed the highest maximum (13)C labels, whereas labels were lower for starch, lipids and pinitol. Label residence times in needles were shorter for sucrose and starch (c. 2 d) than for glucose (c. 6 d). Although our treatments showed no persistent effect on larch carbon relations, low temperature at high altitudes clearly induced a limitation of sink activities (growth, respiration, root exudation), expressed in slower carbon transfer and higher NCC concentrations. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  9. Molecular distribution and compound-specific stable carbon isotopic composition of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls in PM2.5 from Beijing, China

    Directory of Open Access Journals (Sweden)

    W. Zhao


    Full Text Available This study investigates the seasonal variation, molecular distribution and stable carbon isotopic composition of diacids, oxocarboxylic acids and α-dicarbonyls to better understand the sources and formation processes of fine aerosols (PM2.5 in Beijing. The concentrations of total dicarboxylic acids varied from 110 to 2580 ng m−3, whereas oxoacids (9.50–353 ng m−3 and dicarbonyls (1.50–85.9 ng m−3 were less abundant. Oxalic acid was found to be the most abundant individual species, followed by succinic acid or occasionally by terephthalic acid (tPh, a plastic waste burning tracer. Ambient concentrations of phthalic acid (37.9 ± 27.3 ng m−3 and tPh (48.7 ± 51.1 ng m−3 were larger in winter than in other seasons, illustrating that fossil fuel combustion and plastic waste incineration contribute more to wintertime aerosols. The year-round mass concentration ratios of malonic acid to succinic acid (C3 ∕ C4 were relatively low by comparison with those in other urban aerosols and remote marine aerosols. The values were less than or equal to unity in Beijing, implying that the degree of photochemical formation of diacids in Beijing is insignificant. Moreover, strong correlation coefficients of major oxocarboxylic acids and α-dicarbonyls with nss-K+ suggest that biomass burning contributes significantly to these organic acids and related precursors. The mean δ13C value of succinic acid is the highest among all species, with values of −17.1 ± 3.9 ‰ (winter and −17.1 ± 2.0 ‰ (spring, while malonic acid is more enriched in 13C than others in autumn (−17.6 ± 4.6 ‰ and summer (−18.7 ± 4.0 ‰. The δ13C values of major species in Beijing aerosols are generally lower than those in the western North Pacific atmosphere, the downwind region, which indicates that stable carbon isotopic compositions of diacids depend on their precursor sources in Beijing. Therefore, our

  10. Stable isotope

    African Journals Online (AJOL)

    Results of the study suggest that there are two main carbon pathways for plankton and nekton in the Kariega estuary, carbon derived from the eelgrass and its associated epiphytes and carbon which has its origins in the salt marsh riparian vegetation and zooplankton. Keywords: stable isotope analysis; temperate estuary; ...

  11. Development and validation of an universal interface for compound-specific stable isotope analysis of chlorine (37Cl/35Cl) by GC-high-temperature conversion (HTC)-MS/IRMS. (United States)

    Renpenning, Julian; Hitzfeld, Kristina L; Gilevska, Tetyana; Nijenhuis, Ivonne; Gehre, Matthias; Richnow, Hans-Hermann


    A universal application of compound-specific isotope analysis of chlorine was thus far limited by the availability of suitable analysis techniques. In this study, gas chromatography in combination with a high-temperature conversion interface (GC-HTC), converting organic chlorine in the presence of H2 to gaseous HCl, was coupled to a dual-detection system, combining an ion trap mass spectrometer (MS) and isotope-ratio mass spectrometer (IRMS). The combination of the MS/IRMS detection enabled a detailed characterization, optimization, and online monitoring of the high-temperature conversion process via ion trap MS as well as a simultaneous chlorine isotope analysis by the IRMS. Using GC-HTC-MS/IRMS, chlorine isotope analysis at optimized conversion conditions resulted in very accurate isotope values (δ(37)Cl(SMOC)) for measured reference material with known isotope composition, including chlorinated ethylene, chloromethane, hexachlorocyclohexane, and trichloroacetic acids methyl ester. Respective detection limits were determined to be <15 nmol Cl on column with achieved precision of <0.3‰.

  12. Compound-Specific Sulfur Isotope Analysis of Petroleum Gases. (United States)

    Said-Ahmad, Ward; Wong, Kenneth; Mcnall, Monaca; Shawar, Lubna; Jacksier, Tracey; Turich, Courtney; Stankiewicz, Artur; Amrani, Alon


    We describe a simple, sensitive, and robust method for sulfur isotope ratio (34S/32S) analysis of ppm-level organic sulfur compounds (OSCs) in the presence of percent-level H2S. The method uses a gas chromatograph (GC) coupled with a multicollector inductively coupled plasma mass spectrometer (MC-ICPMS). The GC, equipped with a gas inlet and a valve that transfers the H2S to a thermal conductivity detector (TCD), enables a precise heart cut and prevents the saturation of the MC-ICPMS. The sensitivity and accuracy of the method are better than 0.3‰ for OSCs at a concentration of 25 pmol or 1.4 ppm, and better than 0.5‰ for concentrations ≥0.7 ppm of OSCs. An order of magnitude increase in sensitivity, with no effect on accuracy, can be achieved if the loop volume (0.5 mL) is changed to 5 mL. High concentrations of methane (95% v/v) and/or H2S (20% v/v) had no effect (within 0.5‰) on the precision and accuracy of the gas sample containing 2 ppm of OSCs after heart cut. The applicability and robustness of this method are demonstrated on a gas sample (10% v/v H2S) that was produced by pyrolysis of sulfur-rich kerogen. The results show good precision and reveal sulfur isotope variability between individual OSCs that may represent key processes during formation and degradation of OSCs.

  13. Compound-Specific Isotope Analysis of Nitroaromatic Contaminant Transformations by Nitroarene Dioxygenases (United States)

    Pati, Sarah G.; Kohler, Hans-Peter E.; Hofstetter, Thomas B.


    Dioxygenation is an important biochemical reaction that often initiates the mineralization of recalcitrant organic contaminants such as nitroaromatic explosives, chlorinated benzenes, and polycyclic aromatic hydrocarbons. However, to assess the extent of dioxygenation in contaminated environments is difficult because of competing transformation processes and further reactions of the dioxygenation products. Compound-specific isotope analysis (CSIA) offers a new approach to reliably quantify biodegradation initiated by dioxygenation based on changes in stable isotope ratios of the pollutant. For CSIA it is essential to know the kinetic isotope effects (KIEs) pertinent to the dioxygenation mechanism of organic contaminants. Unfortunately, the range of KIEs of such reactions is poorly constrained although many dioxygenase enzymes with a broad substrate specificity have been reported. Dioxygenase enzymes usually exhibit complex reaction kinetics involving multiple substrates and substrate-specific binding modes which makes the determination of KIEs challenging. The goal of this study was to explore the magnitude and variability of 13C-, 2H-, and 15N-KIEs for the dioxygenation of one contaminant class, that is nitroaromatic contaminants (NACs). To this end, we investigated the C, H, and N isotope fractionation during the dioxygenation of nitrobenzene (NB), 2-nitrotoluene (2-NT), and 3-nitrotoluene (3-NT) by pure cultures, E. coli clones, cell extracts, and purified enzymes. From isotope fractionations measured in the substrates and reaction products, we determined dioxygenation KIEs for different combinations of the three substrates with nitrobenzene dioxygenase (NBDO) and 2-nitrotoluene dioxygenase (2NTDO). The 13C-, 2H-, and 15N-KIEs for the dioxygenation of NB by NBDO were consistent for all experimental systems considered (i.e., Comamonas sp. Strain JS765, E. coli clones, cell extracts of E. coli clones, and purified NBDO). This observation suggests that the isotope

  14. Demonstration of compound-specific isotope analysis of hydrogen isotope ratios in chlorinated ethenes. (United States)

    Kuder, Tomasz; Philp, Paul


    High-temperature pyrolysis conversion of organic analytes to H(2) in hydrogen isotope ratio compound-specific isotope analysis (CSIA) is unsuitable for chlorinated compounds such as trichloroethene (TCE) and cis-1,2-dichloroethene (DCE), due to competition from HCl formation. For this reason, the information potential of hydrogen isotope ratios of chlorinated ethenes remains untapped. We present a demonstration of an alternative approach where chlorinated analytes reacted with chromium metal to form H(2) and minor amounts of HCl. The values of δ(2)H were obtained at satisfactory precision (± 10 to 15 per thousand), however the raw data required daily calibration by TCE and/or DCE standards to correct for analytical bias that varies over time. The chromium reactor has been incorporated into a purge and trap-CSIA method that is suitable for CSIA of aqueous environmental samples. A sample data set was obtained for six specimens of commercial product TCE. The resulting values of δ(2)H were between -184 and +682 ‰, which significantly widened the range of manufactured TCE δ(2)H signatures identified by past work. The implications of this finding to the assessment of TCE contamination are discussed.

  15. Carbon sources in the Beaufort Sea revealed by molecular lipid biomarkers and compound specific isotope analysis


    Tolosa, Imma; Fiorini, S.; Gasser, Beat; Martín, Jacobo; Miquel, J.C.


    Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids) and compound specific isotope analysis of suspended particulate organic matter (SPM) and surface sediments of the Mackenzie Shelf and slope (Southeast Beaufort Sea, Arctic Ocean), were studied in summer 2009. The concentrations of the molecular lipid markers, characteristic of known organic matter sources, were grouped and used as proxies to evaluate the relative importance of fresh algal, detrital algal, foss...

  16. Evaluation of functional groups responsible for chloroform formation during water chlorination using compound specific isotope analysis. (United States)

    Arnold, William A; Bolotin, Jakov; Von Gunten, Urs; Hofstetter, Thomas B


    Compound-specific isotope analysis was used to monitor the delta(13)C signature of chloroform produced upon the chlorination of model compounds representing natural organic matter functional groups (resorcinol, acetylacetone, acetophenone, phenol, and 2,4,6-trichlorophenol) and a natural water sample. For each model compound, a different apparent kinetic isotope effect was found for chloroform formation. Normal isotope effects were found for resorcinol, acetylacetone, and acetophenone, and ranged from 1.009 +/- 0.002 to 1.024 +/- 0.004. For the two phenols, an inverse effect was found (0.980 +/- 0.004). Lake Zürich water also had a inverse effect (0.997 +/- NOM, but that other functional groups may also participate. The apparent 13C kinetic isotope effect for the addition/ elimination reaction of 1,1,1-trichloropropanone mediated by OH- to yield chloroform is 1.014 +/- 0.002. A comparison of this value to those found for the chlorination of the model precursors and an evaluation of the differences in chloroform production kinetics for the different model precursors argue against a mechanism in which all NOM precursors react via a common intermediate. Compound specific isotope analysis may give additional insights into chloroform formation mechanisms beyond those allowed by current techniques.

  17. Effects of decalcification on bulk and compound-specific nitrogen and carbon isotope analyses of dentin. (United States)

    Brault, Emily K; Koch, Paul L; Gier, Elizabeth; Ruiz-Cooley, R I; Zupcic, Jessica; Gilbert, Kwasi N; McCarthy, Matthew D


    For bulk carbon and nitrogen isotope analysis of dentin, samples are typically decalcified. Since the non-protein carbon in dentin is low, whole sample analysis may produce reliable data. Compound-specific isotope analysis (CSIA) of bone and tooth dentin protein is a powerful tool for reconstructing the flow of carbon and nitrogen in modern and past food webs. Decalcification has also been used to prepare bone and dentin samples for CSIA, but the effects of this process on bulk dentin, amino acid composition, and their specific isotope values are not known. The bulk isotope values of raw and decalcified dentin from a sperm whale tooth were measured to determine the effects of decalcification and the accuracy of untreated dentin results. CSIA was also performed on decalcified and raw dentin to examine differences in the amino acid isotope values and molar composition between these two approaches. Analysis of raw dentin yields precise and accurate bulk isotope measurements for this animal. The isotopic values of decalcified samples and raw dentin for individual amino acids were similar, but the average of the isotope value offsets between the two sample types was significant. The presence of inorganic material complicated raw sample processing for individual amino acid isotope values, and may have contributed to the isotopic differences between decalcified and raw samples. Decalcification is not needed to measure bulk isotope values in dentin from this modern odontocete, probably because the lipid and carbonate concentrations are low and the carbon isotope values of dentin protein and carbonate are similar. This method should not be applied in some cases (e.g., with fossil dentin and modern bone). Decalcification should still be used prior to CSIA since significant matrix issues occur with raw dentin processing and decalcification does not alter the amino acid molar composition or isotopic values of dentin. Copyright © 2014 John Wiley & Sons, Ltd.

  18. Compound-specific isotopes of fatty acids as indicators of trophic interactions in the East China Sea ecosystem (United States)

    Wu, Ying; Wang, Na; Zhang, Jing; Wan, Ruijing; Dai, Fangqun; Jin, Xianshi


    The composition and compound-specific isotopes of fatty acids were studied within food webs in the East China Sea. Lipid-normalized stable carbon isotopes of total organic carbon had a good correlation with trophic level. Variations in fatty acid compositions among diff erent species were observed but were unclear. Diff erent dietary structures could be traced from molecular isotopes of selected fatty acids in the Shiba shrimp ( Matapenaeus joyneri), the coastal mud shrimp ( Solenocera crassicornis) and the northern Maoxia shrimp ( Acetes chinensis). Both M. joyneri and S. crassicornis are mainly benthos feeders, while A. chinensis is a pelagic species, although they have a similar fatty acid composition. There was a good correlation for isotopes of arachidonic acid (C20:4n6; ARA) and docosahexaenoic acid (C22:6n3; DHA) among pelagic species from higher trophic levels. The isotopic compositions of DHA in benthic species were more negative than those of pelagic species at the same trophic level. The fact that the diet of benthic species contains more degraded items, the carbon isotopes of which are derived from a large biochemical fraction, may be the reason for this variation. A comparative study of benthic and pelagic species demonstrated the diff erent carbon sources in potential food items and the presence of a more complex system at the water-sediment interface.

  19. Compound-Specific Isotope Analysis of Diesel Fuels in a Forensic Investigation

    Directory of Open Access Journals (Sweden)

    Syahidah Akmal Muhammad


    Full Text Available Compound-specific isotope analysis (CSIA offers great potential as a tool to provide chemical evidence in a forensic investigation. Many attempts to trace environmental oil spills were successful where isotopic values were particularly distinct. However, difficulties arise when a large data set is analyzed and the isotopic differences between samples are subtle. In the present study, discrimination of diesel oils involved in a diesel theft case was carried out to infer the relatedness of the samples to potential source samples. This discriminatory analysis used a suite of hydrocarbon diagnostic indices, alkanes, to generate carbon and hydrogen isotopic data of the compositions of the compounds which were then processed using multivariate statistical analyses to infer the relatedness of the data set. The results from this analysis were put into context by comparing the data with the δ13C and δ2H of alkanes in commercial diesel samples obtained from various locations in the South Island of New Zealand. Based on the isotopic character of the alkanes, it is suggested that diesel fuels involved in the diesel theft case were distinguishable. This manuscript shows that CSIA when used in tandem with multivariate statistical analysis provide a defensible means to differentiate and source-apportion qualitatively similar oils at the molecular level. This approach was able to overcome confounding challenges posed by the near single-point source of origin i.e. the very subtle differences in isotopic values between the samples.

  20. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

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


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

  1. Compound-specific amino acid isotopic analyses of invertebrates in the Chukchi Sea: New insights on food web dynamics (United States)

    Zhang, M.; Cooper, L. W.; Biasatti, D. M.; Kedra, M.; Grebmeier, J. M.


    Food web dynamics in the Chukchi Sea have been previously evaluated using bulk analysis of stable carbon and nitrogen isotopes of organisms. However, recent advances in compound-specific stable isotope analysis of amino acids indicate the potential to better identify the contributions of different dietary sources (e.g., pelagic vs. benthic, ice algae vs. phytoplankton) and to resolve complexities of food web structure that are difficult to address with bulk isotope analysis. Here we combine amino acid δ13C and δ15N data measured from primary producers and tissues of bivalves, polychaetes and other benthic invertebrates collected during two cruises in the summer of 2013 and 2015 in the Pacific Arctic. The results showed spatial variation of carbon isotope values in amino acids with difference up to 6 per mil for each individual species or taxa studied, indicating a shift in the food-web baseline geographically. Furthermore, the spatial variation in isotopic values was related to environmental factors, specifically sea ice extent, and total organic carbon, total organic nitrogen and the carbon/nitrogen ratio of the organic fractions of surface sediments. Results also indicated that trophic levels, as estimated by differences in the nitrogen isotope composition of glutamic acid and phenylalanine [Δ15Nglu-phe (δ15Nglu - δ15Nphe)], varied spatially by 0.5 to 1.5 trophic levels for certain species or taxa such as Macoma calcarea, Maldanidae and Ampelisca, indicating trophic level shifts that were associated with the food quality of organic matter in the organic fraction of the sediments. These results can be potentially used to predict future food web change in this high latitude marine system that is known for its ecological importance and on-going environmental changes, including warming and sea ice decline.

  2. Compound-specific hydrogen isotope analysis of heteroatom-bearing compounds via gas chromatography-chromium-based high-temperature conversion (Cr/HTC)-isotope ratio mass spectrometry. (United States)

    Renpenning, Julian; Kümmel, Steffen; Hitzfeld, Kristina L; Schimmelmann, Arndt; Gehre, Matthias


    The traditional high-temperature conversion (HTC) approach toward compound-specific stable isotope analysis (CSIA) of hydrogen for heteroatom-bearing (i.e., N, Cl, S) compounds has been afflicted by fractionation bias due to formation of byproducts HCN, HCl, and H2S. This study presents a chromium-based high-temperature conversion (Cr/HTC) approach for organic compounds containing nitrogen, chlorine, and sulfur. Following peak separation along a gas chromatographic (GC) column, the use of thermally stable ceramic Cr/HTC reactors at 1100-1500 °C and chemical sequestration of N, Cl, and S by chromium result in quantitative conversion of compound-specific organic hydrogen to H2 analyte gas. The overall hydrogen isotope analysis via GC-Cr/HTC-isotope ratio mass spectrometry (IRMS) achieved a precision of better than ± 5 mUr along the VSMOW-SLAP scale. The accuracy of GC-Cr/HTC-IRMS was validated with organic reference materials (RM) in comparison with online EA-Cr/HTC-IRMS and offline dual-inlet IRMS. The utility and reliability of the GC-Cr/HTC-IRMS system were documented during the routine measurement of more than 500 heteroatom-bearing organic samples spanning a δ(2)H range of -181 mUr to 629 mUr.

  3. Compound-specific chlorine isotope analysis of polychlorinated biphenyls isolated from Aroclor and Clophen technical mixtures. (United States)

    Mandalakis, Manolis; Holmstrand, Henry; Andersson, Per; Gustafsson, Orjan


    Compound-specific chlorine isotope analysis (CSIA-Cl) is promising as a novel and powerful method for monitoring in situ degradation of organochlorines in the environment and for source fingerprinting purposes. In order to apply CSIA-Cl in field studies of polychlorinated biphenyls (PCBs), the chlorine isotopic composition (delta(37)Cl) of individual PCB congeners in source materials must be known. In the present study, we determined delta(37)Cl of 18 congeners isolated from three widely produced technical mixtures. All congeners provided delta(37)Cl ranging between -1.9 per thousand and -3.5 per thousand. Although the comparable products Aroclor 1242 (-2.0 per thousand to -2.5 per thousand) and Clophen A30 (-1.9 per thousand to -3.0 per thousand) were synthesized by different industries, they provided similar delta(37)Cl for the same type of congeners. On the contrary, the more chlorinated congeners present in Aroclor 1254 (-2.1 to -3.5 per thousand) were more (37)Cl depleted compared to Aroclor 1242 manufactured by the same company. Overall, delta(37)Cl of PCB congeners decreased by -0.26 per thousand for each additional chlorine atom.

  4. Biotransformation of benzotriazoles: insights from transformation product identification and compound-specific isotope analysis. (United States)

    Huntscha, Sebastian; Hofstetter, Thomas B; Schymanski, Emma L; Spahr, Stephanie; Hollender, Juliane


    Benzotriazoles are widely used domestic and industrial corrosion inhibitors and have become omnipresent organic micropollutants in the aquatic environment. Here, the range of aerobic biological degradation mechanisms of benzotriazoles in activated sludge was investigated. Degradation pathways were elucidated by identifying transient and persistent transformation products in batch experiments using liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS). In addition, initial reactions were studied using compound-specific isotope analysis (CSIA). Biodegradation half-lives of 1.0 days for 1H-benzotriazole, 8.5 days for 4-methyl-1H-benzotriazole, and 0.9 days for 5-methyl-1H-benzotriazole with activated sludge confirmed their known partial persistence in conventional wastewater treatment. Major transformation products were identified as 4- and 5-hydroxy-1H-benzotriazole for the degradation of 1H-benzotriazole, and 1H-benzotriazole-5-carboxylic acid for the degradation of 5-methyl-1H-benzotriazole. These transformation products were found in wastewater effluents, showing their environmental relevance. Many other candidate transformation products, tentatively identified by interpretation of HR-MS/MS spectra, showed the broad range of possible reaction pathways including oxidation, alkylation, hydroxylation and indicate the significance of cometabolic processes for micropollutant degradation in biological wastewater treatment in general. The combination of evidence from product analysis with the significant carbon and nitrogen isotope fractionation suggests that aromatic monohydroxylation is the predominant step during the biotransformation of 1H-benzotriazole.

  5. Bulk and Compound Specific Isotope Analysis Provide Insights into Habitat Use and Diet Variability Among Female Sperm Whales (Physeter macrocephalus) from the Eastern Tropical Pacific (United States)

    Zupcic-Moore, J. R.; Ruiz-Cooley, R. I.; McCarthy, M. D.; Koch, P. L.


    Sperm whales (Physeter macrocephalus) have a strong social structure and females form sympatric clans that span thousands of kilometers and encompass thousands of whales. We investigated variability in foraging habitat and diet through the life history of ten female sperm whales from the Eastern Tropical Pacific (ETP), using coupled bulk and compound specific amino acid stable isotope measurements made on annual tooth growth layers. We identified three broad temporal patterns in annual records of bulk nitrogen (δ15N) and carbon (δ13C) isotope values in sub-groups of individuals: 1) constant, 2) increasing, and 3) decreasing isotopic values between ca.1930 and 1960. These different isotopic patterns suggest that whales sampled may belong to different clans. In addition, average bulk δ15N and δ13C values differed among individuals and appear to be group-specific. This suggests that whales from different sub-groups foraged in different habitats and/or had differing diets. To differentiate between these interpretations, we conducted compound specific amino acid isotope analysis on dentin samples from six whales. Amino acid proxies for baseline δ15N values indicate that bulk variability among whales is due to δ15N differences at the base of the food web, indicating different feeding areas. The δ13C values of essential amino acids, which are positively correlated to bulk δ13C values, support this conclusion. Together, the compound specific and bulk annual records suggest that whales with higher isotopic values likely foraged in regions closer to the coast throughout their lives, while whales with lower isotopic values likely foraged further offshore. Overall, our data suggest clear spatial segregation of clans within a similar ocean region. Since molecular analysis cannot yet distinguish genetic variability among whale clans, we suggest that stable isotope analysis can help to identify clans and their foraging ecology, based on habitat use.

  6. Environmental Forensics : Compound Specific Isotope Analysis Of PAHs. Study Of A Former Coal Tar Plant. (United States)

    Assal, A.; Doherty, R.; Dickson, K.; Kalin, R. M.


    Stable carbon isotopic fingerprints of PAHs obtained by GC-IRMS have often been used in source apportionment studies. The use of PAHs in environmental forensics relies on the assumption that carbon isotopic fractionation caused by microbial degradation is less significant for these heavy molecular weight compounds than for lighter molecules such as chlorinated solvents or BTEX. Carbon isotopic fractionation of PAHs during degradation is still not well understood. The aim of this study was to assess the potential of CSIA of PAHs for environmental forensics applications at a complex (hydrogeology affected by tidal fluxes) former coal tar plant. In this work, soil samples from a tar works site were analyzed. The tar works operated on the site over a period of sixty years. A source apportionment study was first carried out based on 90 target PAHs quantified by GC-MS. These results were then compared to carbon isotope fingerprints. The separation of compounds of interest from co-extracted interfering peaks is a crucial prerequisite of CSIA by GC-IRMS. Hence, a sample preparation method which allowed the determination of precise carbon isotope signatures for up to 35 compounds per soil extract was developed, validated and applied to the samples previously analyzed by GC- MS. Although most soil samples were shown to be related to the point source tar contamination, PAHs ratios and principal component analysis of abundances highlighted some samples with unusual patterns, suggesting the input of a second source of contaminants. However, no statistically significant variation of the isotopic fingerprints of heavy molecular weight PAHs of these samples was observed. This was inconsistent with the first diagnosis. Since evidence was provided that most samples were only affected by a single source of contaminants, carbon isotopic fractionation was investigated in-situ. Importantly, naphthalene and 2- and 1- methylnaphthalenes isotopic fractionation was observed in a vertical

  7. Stable isotope analysis of the bioelements: an introduction. (United States)

    Flenker, Ulrich


    The abundances of the stable isotopes of the bioelements are not constant. Subtle, but significant, variations may be induced by physical, physiological and biochemical processes. These variations may be detected and quantified. Often, isotope fingerprints are characteristic of certain processes and may reveal information concerning the sources and origins of compounds of interest. Moreover, natural variabilities of stable isotopes may be exploited in order to perform tracer experiments. The most accurate technology to perform stable isotope analysis is (gas) isotope ratio MS (IRMS). Compound-specific approaches employ hyphenation of GC and LC to IRMS. In these approaches, complete conversion to simple gases prior to MS is required. Analysis by stable isotope ratio spectroscopy currently approaches the accuracy of IRMS. However, for bioanalytical projects, it is still predominantly confined to material synthetically enriched with stable isotopes.

  8. Compound-Specific Isotope Analysis (CSIA Application for Source Apportionment and Natural Attenuation Assessment of Chlorinated Benzenes

    Directory of Open Access Journals (Sweden)

    Luca Alberti


    Full Text Available In light of the complex management of chlorobenzene (CB contaminated sites, at which a hydraulic barrier (HB for plumes containment is emplaced, compound-specific stable isotope analysis (CSIA has been applied for source apportionment, for investigating the relation between the upgradient and downgradient of the HB, and to target potential CB biodegradation processes. The isotope signature of all the components potentially involved in the degradation processes has been expressed using the concentration-weighted average δ13C of CBs + benzene (δ13Csum. Upgradient of the HB, the average δ13Csum of −25.6‰ and −29.4‰ were measured for plumes within the eastern and western sectors, respectively. Similar values were observed for the potential sources, with δ13Csum values of −26.5‰ for contaminated soils and −29.8‰ for the processing water pipeline in the eastern and western sectors, respectively, allowing for apportioning of these potential sources to the respective contaminant plumes. For the downgradient of the HB, similar CB concentrations but enriched δ13Csum values between −24.5‰ and −25.9‰ were measured. Moreover, contaminated soils showed a similar δ13Csum signature of −24.5‰, thus suggesting that the plumes likely originate from past activities located in the downgradient of the HB. Within the industrial property, significant δ13C enrichments were measured for 1,2,4-trichlorobenzene (TCB, 1,2-dichlorobenzene (DCB, 1,3-DCB, and 1,4-DCBs, thus suggesting an important role for anaerobic biodegradation. Further degradation of monochlorobenzene (MCB and benzene was also demonstrated. CSIA was confirmed to be an effective approach for site characterization, revealing the proper functioning of the HB and demonstrating the important role of natural attenuation processes in reducing the contamination upgradient of the HB.

  9. Stable Isotope Data (United States)

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

  10. Compound specific isotopic fractionation patterns suggest different carbon metabolisms among Chloroflexus-like bacteria in hot spring microbial mats

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Meer, M.T.J. van der; Schouten, S.; Leeuw, J.W. de; Ward, D.M.


    Stable carbon isotope fractionations between dissolved inorganic carbon and lipid biomarkers suggest photoautotrophy by Chloroflexus-like organisms in sulfidic and nonsulfidic Yellowstone hot springs. Where co-occurring, cyanobacteria appear to cross-feed Chloroflexus-like organisms supporting

  11. Study of thermochemical sulfate reduction mechanism using compound specific sulfur isotope analysis (United States)

    Meshoulam, Alexander; Ellis, Geoffrey S.; Ahmad, Ward Said; Deev, Andrei; Sessions, Alex L.; Tang, Yongchun; Adkins, Jess F.; Liu, Jinzhong; Gilhooly, William P.; Aizenshtat, Zeev; Amrani, Alon


    The sulfur isotopic fractionation associated with the formation of organic sulfur compounds (OSCs) during thermochemical sulfate reduction (TSR) was studied using gold-tube pyrolysis experiments to simulate TSR. The reactants used included n-hexadecane (n-C16) as a model organic compound with sulfate, sulfite, or elemental sulfur as the sulfur source. At the end of each experiment, the S-isotopic composition and concentration of remaining sulfate, H2S, benzothiophene, dibenzothiophene, and 2-phenylthiophene (PT) were measured. The observed S-isotopic fractionations between sulfate and BT, DBT, and H2S in experimental simulations of TSR correlate well with a multi-stage model of the overall TSR process. Large kinetic isotope fractionations occur during the first, uncatalyzed stage of TSR, 12.4‰ for H2S and as much as 22.2‰ for BT. The fractionations decrease as the H2S concentration increases and the reaction enters the second, catalyzed stage. Once all of the oxidizable hydrocarbons have been consumed, sulfate reduction ceases and equilibrium partitioning then dictates the fractionation between H2S and sulfate (∼17‰).

  12. Study of thermochemical sulfate reduction mechanism using compound specific sulfur isotope analysis (United States)

    Meshoulam, Alexander; Ellis, Geoffrey S.; Said Ahmad, Ward; Deev, Andrei; Sessions, Alex L.; Tang, Yongchun; Adkins, Jess F.; Liu, Jinzhong; Gilhooly, William P.; Aizenshtat, Zeev; Amrani, Alon


    The sulfur isotopic fractionation associated with the formation of organic sulfur compounds (OSCs) during thermochemical sulfate reduction (TSR) was studied using gold-tube pyrolysis experiments to simulate TSR. The reactants used included n-hexadecane (n-C16) as a model organic compound with sulfate, sulfite, or elemental sulfur as the sulfur source. At the end of each experiment, the S-isotopic composition and concentration of remaining sulfate, H2S, benzothiophene, dibenzothiophene, and 2-phenylthiophene (PT) were measured. The observed S-isotopic fractionations between sulfate and BT, DBT, and H2S in experimental simulations of TSR correlate well with a multi-stage model of the overall TSR process. Large kinetic isotope fractionations occur during the first, uncatalyzed stage of TSR, 12.4‰ for H2S and as much as 22.2‰ for BT. The fractionations decrease as the H2S concentration increases and the reaction enters the second, catalyzed stage. Once all of the oxidizable hydrocarbons have been consumed, sulfate reduction ceases and equilibrium partitioning then dictates the fractionation between H2S and sulfate (∼17‰). Experiments involving sparingly soluble CaSO4 show that during the second catalytic phase of TSR the rate of sulfate reduction exceeds that of sulfate dissolution. In this case, there is no apparent isotopic fractionation between source sulfate and generated H2S, as all of the available sulfate is effectively reduced at all reaction times. When CaSO4 is replaced with fully soluble Na2SO4, sulfate dissolution is no longer rate limiting and significant S-isotopic fractionation is observed. This supports the notion that CaSO4 dissolution can lead to the apparent lack of fractionation between H2S and sulfate produced by TSR in nature. The S-isotopic composition of individual OSCs record information related to geochemical reactions that cannot be discerned from the δ34S values obtained from bulk phases such as H2S, oil, and sulfate minerals, and

  13. Compound-Specific Carbon, Nitrogen, and Hydrogen Isotopic Ratios for Amino Acids in CM and CR Chondrites and their use in Evaluating Potential Formation Pathways (United States)

    Elsila, Jamie E.; Charnley, Steven B.; Burton, Aaron S.; Glavin, Daniel P.; Dworkin, Jason P.


    Stable hydrogen, carbon, and nitrogen isotopic ratios (oD, 013C, and olSN) of organic compounds can revcal information about their origin and formation pathways. Several formation mechanisms and environments have been postulated for the amino acids detected in carbonaceous chondrites. As each proposed mechanism utilizes different precursor molecules, the isotopic signatures of the resulting amino acids may indicate the most likely of these pathways. We have applied gas chromatography with mass spectrometry and combustion isotope ratio mass spectrometry to measure the compound-specific C, N, and H stable isotopic ratios of amino acids from seven CM and CR carbonaceous chondrites: CM1I2 Allan Hills (ALH) 83100, CM2 Murchison, CM2 Lewis Cliff (LEW) 90500, CM2 Lonewolf Nunataks (LON) 94101, CRZ Graves Nunataks (GRA) 95229, CRZ Elephant Moraine (EET) 92042, and CR3 Queen Alexandra Range (QUE) 99177. We compare the isotopic compositions of amino acids in these meteorites with predictions of expected isotopic enrichments from potential formation pathways. We observe trends of decreasing ODC and increasing oD with increasing carbon number in the aH, (l-NH2 amino acids that correspond to predictions made for formation via Streckercyanohydrin synthesis. We also observe light ODC signatures for -alanine, which may indicate either formation via Michael addition or via a pathway that forms primarily small, straight-chain, amine-terminal amino acids (n-ro-amino acids). Higher deuterium enrichments are observed in amethyl amino acids, indicating formation of these amino acids or their precursors in cold interstellar or nebular environments. Finally, individual amino acids are more enriched in deuterium in CR chondrites than CM chondrites, reflecting different parent-body chemistry.

  14. Validation of adsorbents for sample preconcentration in compound-specific isotope analysis of common vapor intrusion pollutants. (United States)

    Klisch, Monika; Kuder, Tomasz; Philp, R Paul; McHugh, Thomas E


    Isotope ratios of volatile organic compounds (VOCs) in the environment are often of interest in contaminant fate studies. Adsorbent preconcentration-thermal desorption of VOCs can be used to collect environmental vapor samples for compound-specific isotope analysis (CSIA). While active adsorbent samplers offer logistic benefits in handling large volumes of air, their performance in preserving VOCs isotope ratios was not previously tested under sampling conditions corresponding to typical indoor air sampling conditions. In this study, the performance of selected adsorbents was tested for preconcentration of TCE (for determination of C and Cl isotope ratios), PCE (C and Cl) and benzene (C and H). The key objective of the study was to identify the adsorbent(s) permitting preconcentration of the target VOCs present in air at low μg/m(3) concentrations, without significant alteration of their isotope ratios. Carboxen 1016 was found to perform well for the full range of tested parameters. Carboxen 1016 can be recommended for sampling of TCE, PCE and benzene, for CSIA, from air volumes up to 100 L. Variable extent of isotope ratio alteration was observed in the preconcentration of the target VOCs on Carbopack B and Carbopack X, resulting from partial analyte loss via adsorbent bed breakthrough and (possibly) via incomplete desorption. The results from testing the Carbopack B and Carbopack X highlight the need of adsorbent performance validation at conditions fully representative of actual sample collection conditions, and caution against extrapolation of performance data toward more challenging sampling conditions. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. The application of compound-specific isotope analysis of fatty acids for traceability of sea cucumber (Apostichopus japonicus) in the coastal areas of China. (United States)

    Liu, Yu; Zhang, Xufeng; Li, Ying; Wang, Haixia


    Geographical origin traceability is an important issue for controlling the quality of seafood and safeguarding the interest of consumers. In the present study, a new method of compound-specific isotope analysis (CSIA) of fatty acids was established to evaluate its applicability in establishing the origin traceability of Apostichopus japonicus in the coastal areas of China. Moreover, principal component analysis (PCA) and discriminant analysis (DA) were applied to distinguish between the origins of A. japonicus. The results show that the stable carbon isotope compositions of fatty acids of A. japonicus significantly differ in terms of both season and origin. They also indicate that the stable carbon isotope composition of fatty acids could effectively discriminate between the origins of A. japonicus, except for between Changhai Island and Zhangzi Island in the spring of 2016 because of geographical proximity or the similarity of food sources. The fatty acids that have the highest contribution to identifying the geographical origins of A. japonicus are C22:6n-3, C16:1n-7, C20:5n-3, C18:0 and C23:1n-9, when considering the fatty acid contents, the stable carbon isotope composition of fatty acids and the results of the PCA and DA. We conclude that CSIA of fatty acids, combined with multivariate statistical analysis such as PCA and DA, may be an effective tool for establishing the traceability of A. japonicus in the coastal areas of China. The relevant conclusions of the present study provide a new method for determining the traceability of seafood or other food products. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  16. Stable Chlorine Isotope Fractionation (United States)

    Sharp, Z.


    Chlorine isotope partitioning between different phases is not well understood. Pore fluids can have δ37Cl values as low as -8‰, with neoform sediments having strongly positive values. Most strikingly, volcanic gases have δ37Cl values that cover a range in excess of 14‰ (Barnes et al., this meeting). The large range is difficult to explain in terms of equilibrium fractionation, which, although calculated to be very large for Cl in different oxidation states, should be less than 2‰ between chloride species (Schauble et al., 2003, GCA). To address the discrepancy between Nature and theory, we have measured Cl isotope fractionation for selected equilibrium and disequilibrium experiments in order to identify mechanisms that might lead to large fractionations. 1) NaCl (s,l) NaCl (v): NaCl was sealed in an evacuated silica tube and heated at one end, causing vaporization and reprecipitation of NaCl (v) at the cool end of the tube. The fractionation is 0.2‰ at 700°C (halite-vapor) and 0.7‰ at 800°C (liquid-vapor), respectively. The larger fractionation at higher temperature may be related to equilibrium fractionation between liquid and gas vs. `stripping' of the solid in the lower T experiments. 2) Sodalite NaCl(l): Nepheline and excess NaCl were sealed in a Pt crucible at 825°C for 48 hrs producing sodalite. The measured newly-formed sodalite-NaCl fractionation is -0.2‰. 3) Volatilization of HCl: Dry inert gas was bubbled through HCl solutions and the vapor was collected in a downstream water trap. There was no fractionation for 12.4M HCl (HCl fuming) vapor at 25°C. For a 1 M boiling HCl solution, the HCl-vapor fractionation was ~9‰. The difference is probably related to the degree of dissociation in the acid, with HCl dissolved in water for the highly acidic solutions, and dissociated H3O+ and Cl- for lower concentrations. The HCl volatilization experiments are in contrast to earlier vapor-liquid experiments in NaCl-H2O system, where fractionation was

  17. Characterization of toluene and ethylbenzene biodegradation under nitrate-, iron(III)- and manganese(IV)-reducing conditions by compound-specific isotope analysis. (United States)

    Dorer, Conrad; Vogt, Carsten; Neu, Thomas R; Stryhanyuk, Hryhoriy; Richnow, Hans-Hermann


    Ethylbenzene and toluene degradation under nitrate-, Mn(IV)-, or Fe(III)-reducing conditions was investigated by compound specific stable isotope analysis (CSIA) using three model cultures (Aromatoleum aromaticum EbN1, Georgfuchsia toluolica G5G6, and a Azoarcus-dominated mixed culture). Systematically lower isotope enrichment factors for carbon and hydrogen were observed for particulate Mn(IV). The increasing diffusion distances of toluene or ethylbenzene to the solid Mn(IV) most likely caused limited bioavailability and hence resulted in the observed masking effect. The data suggests further ethylbenzene hydroxylation by ethylbenzene dehydrogenase (EBDH) and toluene activation by benzylsuccinate synthase (BSS) as initial activation steps. Notably, significantly different values in dual isotope analysis were detected for toluene degradation by G. toluolica under the three studied redox conditions, suggesting variations in the enzymatic transition state depending on the available TEA. The results indicate that two-dimensional CSIA has significant potential to assess anaerobic biodegradation of ethylbenzene and toluene at contaminated sites. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Evaluation of ethyl tert-butyl ether biodegradation in a contaminated aquifer by compound-specific isotope analysis and in situ microcosms

    Energy Technology Data Exchange (ETDEWEB)

    Bombach, Petra, E-mail: [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Isodetect GmbH Leipzig, Deutscher Platz 5b, D-04103 Leipzig (Germany); Nägele, Norbert [Kuvier the Biotech Company S.L., Ctra. N-I, p.k. 234–P.E. INBISA 23" a, E-09001 Burgos (Spain); Rosell, Mònica [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristallografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), C/Martí i Franquès s/n, 08028 Barcelona (Spain); Richnow, Hans H. [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Fischer, Anko [Isodetect GmbH Leipzig, Deutscher Platz 5b, D-04103 Leipzig (Germany)


    Highlights: • In situ biodegradation of ETBE was investigated in a fuel contaminated aquifer. • Degradation was studied by CSIA and in situ microcosms in combination with TLFA-SIP. • ETBE was degraded when ETBE was the main groundwater contaminant. • ETBE was also degraded in the presence of BTEX and MTBE. • Hydrochemical analysis indicated aerobic and anaerobic ETBE biodegradation. - Abstract: Ethyl tert-butyl ether (ETBE) is an upcoming groundwater pollutant in Europe whose environmental fate has been less investigated, thus far. In the present study, we investigated the in situ biodegradation of ETBE in a fuel-contaminated aquifer using compound-specific stable isotope analysis (CSIA), and in situ microcosms in combination with total lipid fatty acid (TLFA)-stable isotope probing (SIP). In a first field investigation, CSIA revealed insignificant carbon isotope fractionation, but low hydrogen isotope fractionation of up to +14‰ along the prevailing anoxic ETBE plume suggesting biodegradation of ETBE. Ten months later, oxygen injection was conducted to enhance the biodegradation of petroleum hydrocarbons (PH) at the field site. Within the framework of this remediation measure, in situ microcosms loaded with [{sup 13}C{sub 6}]-ETBE (BACTRAP{sup ®}s) were exposed for 119 days in selected groundwater wells to assess the biodegradation of ETBE by TLFA-SIP under the following conditions: (i) ETBE as main contaminant; (ii) ETBE as main contaminant subjected to oxygen injection; (iii) ETBE plus other PH; (iv) ETBE plus other PH subjected to oxygen injection. Under all conditions investigated, significant {sup 13}C-incorporation into microbial total lipid fatty acids extracted from the in situ microcosms was found, providing clear evidence of ETBE biodegradation.

  19. Assessing Friction Stress on a Liquid Lubricant by Stable Isotope Analysis (United States)


    1999;12:228-9. [11] Bhushan B. Principles and Applications of Tribology. New York, NY: John Wiley & Sons; 1999. [12] Fry B. Stable Isotope Ecology ... Coffin RB. Compound-Specific Isotope Analysis Coupled With Multivariate Statistics to Source-Apportion Hydrocarbon Mixtures. Environ Sci Technol

  20. Monitoring biodegradation of ethene and bioremediation of chlorinated ethenes at a contaminated site using compound-specific isotope analysis (CSIA) (United States)

    Mundle, S.O.C.; Johnson, T.; Lacrampe-Couloume, G.; Perez-De-Mora, A.; Duhamel, M.; Edwards, E.A.; McMaster, M.L.; Cox, E.; Revesz, K.; Lollar, B. Sherwood


    Chlorinated ethenes are commonly found in contaminated groundwater. Remediation strategies focus on transformation processes that will ultimately lead to nontoxic products. A major concern with these strategies is the possibility of incomplete dechlorination and accumulation of toxic daughter products (cis-1,2-dichloroethene (cDCE), vinyl chloride (VC)). Ethene mass balance can be used as a direct indicator to assess the effectiveness of dechlorination. However, the microbial processes that affect ethene are not well characterized and poor mass balance may reflect biotransformation of ethene rather than incomplete dechlorination. Microbial degradation of ethene is commonly observed in aerobic systems but fewer cases have been reported in anaerobic systems. Limited information is available on the isotope enrichment factors associated with these processes. Using compound-specific isotope analysis (CSIA) we determined the enrichment factors associated with microbial degradation of ethene in anaerobic microcosms (ε = −6.7‰ ± 0.4‰, and −4.0‰ ± 0.8‰) from cultures collected from the Twin Lakes wetland area at the Savannah River site in Georgia (United States), and in aerobic microcosms (ε = −3.0‰ ± 0.3‰) from Mycobacterium sp. strain JS60. Under anaerobic and aerobic conditions, CSIA can be used to determine whether biotransformation of ethene is occurring in addition to biodegradation of the chlorinated ethenes. Using δ13C values determined for ethene and for chlorinated ethenes at a contaminated field site undergoing bioremediation, this study demonstrates how CSIA of ethene can be used to reduce uncertainty and risk at a site by distinguishing between actual mass balance deficits during reductive dechlorination and apparent lack of mass balance that is related to biotransformation of ethene.

  1. Stable isotope compounds - production, detection, and application. (United States)

    Zachleder, Vilém; Vítová, Milada; Hlavová, Monika; Moudříková, Šárka; Mojzeš, Peter; Heumann, Hermann; Becher, Johannes R; Bišová, Kateřina


    Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies. Copyright © 2018. Published by Elsevier Inc.

  2. Stable isotopes and biomarkers in microbial ecology

    NARCIS (Netherlands)

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


    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

  3. Evidence of Chlorobenzene Natural Attenuation in Contaminated Sediments Using Compound Specific Isotope Analysis and High Resolution Pore Water Sampling (United States)

    Passeport, E.; Landis, R.; Lacrampe Couloume, G.; Lutz, E. J.; Mack, E. E.; West, K.; Sherwood Lollar, B.


    Contaminated sediments can represent a significant risk for ecosystems and hinder drinking water production if contaminants discharge to surface and ground water. Understanding of contaminant fate and the potential for natural attenuation can help protect aquatic resources. In this study, the fate of chlorobenzene (MCB) and benzene was investigated in a contaminated canal sediment field site located in New Jersey, USA. Compound Specific Isotope Analysis (CSIA) was applied to sediment pore water samples collected with a peeper at high spatial resolution (3 cm) across the sediment - surface water interface (SWI). Samples were collected at three locations in canal sediments, all of which exhibited reducing redox conditions. The largest concentrations were observed in the bottommost portions of the sediment profile, with concentrations ranging from 300 to 2000 µg/L for MCB, and 16 to 180 µg/L for benzene. Conversely, concentrations were below detection limit in the surface water and in the top 6 cm of the sediment. In the zones of highest MCB concentrations, the δ13C values were -26.4 (location C) and -21.9 ‰ (location F), and became progressively more enriched in 13C while concentrations decreased, reaching -23.9 (at 12 cm below the SWI, location C) and -18.4 ‰ (at 16.5 cm below SWI, location F). Benzene was only detected in the bottom 6 cm of the sediment profiles. Benzene δ13C values were -27 (bottommost, i.e., 24 cm deep) to -29.7 ‰ (18 cm deep), in location C. Such significant isotopic enrichments in 13C (2.5 to 3.5 ‰) correlated with MCB and benzene concentration decrease are suggestive of in situ biodegradation. In addition, benzene δ13C values were systematically more depleted in 13C than MCB, suggesting that benzene found in these zones was likely produced from MCB via reductive dechlorination. This study combined for the first time CSIA with high spatial sampling resolution in surface water sediments. This setup enabled not only detection of

  4. Effects of thermal maturation and thermochemical sulfate reduction on compound-specific sulfur isotopic compositions of organosulfur compounds in Phosphoria oils from the Bighorn Basin, USA (United States)

    Ellis, Geoffrey S.; Said-Ahamed, Ward; Lillis, Paul G.; Shawar, Lubna; Amrani, Alon


    Compound-specific sulfur isotope analysis was applied to a suite of 18 crude oils generated from the Permian Phosphoria Formation in the Bighorn Basin, western USA. These oils were generated at various levels of thermal maturity and some experienced thermochemical sulfate reduction (TSR). This is the first study to examine the effects of thermal maturation on stable sulfur isotopic compositions of individual organosulfur compounds (OSCs) in crude oil. A general trend of 34S enrichment in all of the studied compounds with increasing thermal maturity was observed, with the δ34S values of alkyl-benzothiophenes (BTs) tending to be enriched in 34S relative to those of the alkyl-dibenzothiophenes (DBTs) in lower-maturity oils. As thermal maturity increases, δ34S values of both BTs and DBTs become progressively heavier, but the difference in the average δ34S value of the BTs and DBTs (Δ34S BT-DBT) decreases. Differences in the isotopic response to thermal stress exhibited by these two compound classes are considered to be the result of relative differences in their thermal stabilities. TSR-altered Bighorn Basin oils have OSCs that are generally enriched in 34S relative to non-TSR-altered oils, with the BTs being enriched in 34S relative to the DBTs, similar to the findings of previous studies. However, several oils that were previously interpreted to have been exposed to minor TSR have Δ34S BT-DBT values that do not support this interpretation. The δ34S values of the BTs and DBTs in some of these oils suggest that they did not experience TSR, but were derived from a more thermally mature source. The heaviest δ34S values observed in the OSCs are enriched in 34S by up to 10‰ relative to that of Permian anhydrite in the Bighorn Basin, suggesting that there may be an alternate or additional source of sulfate in some parts of the basin. These results indicate that the sulfur isotopic composition of OSCs in oil provides a sensitive indicator for the extent of TSR

  5. Optimization of the solvent-based dissolution method to sample volatile organic compound vapors for compound-specific isotope analysis. (United States)

    Bouchard, Daniel; Wanner, Philipp; Luo, Hong; McLoughlin, Patrick W; Henderson, James K; Pirkle, Robert J; Hunkeler, Daniel


    The methodology of the solvent-based dissolution method used to sample gas phase volatile organic compounds (VOC) for compound-specific isotope analysis (CSIA) was optimized to lower the method detection limits for TCE and benzene. The sampling methodology previously evaluated by [1] consists in pulling the air through a solvent to dissolve and accumulate the gaseous VOC. After the sampling process, the solvent can then be treated similarly as groundwater samples to perform routine CSIA by diluting an aliquot of the solvent into water to reach the required concentration of the targeted contaminant. Among solvents tested, tetraethylene glycol dimethyl ether (TGDE) showed the best aptitude for the method. TGDE has a great affinity with TCE and benzene, hence efficiently dissolving the compounds during their transition through the solvent. The method detection limit for TCE (5±1μg/m3) and benzene (1.7±0.5μg/m3) is lower when using TGDE compared to methanol, which was previously used (385μg/m3 for TCE and 130μg/m3 for benzene) [2]. The method detection limit refers to the minimal gas phase concentration in ambient air required to load sufficient VOC mass into TGDE to perform δ13C analysis. Due to a different analytical procedure, the method detection limit associated with δ37Cl analysis was found to be 156±6μg/m3 for TCE. Furthermore, the experimental results validated the relationship between the gas phase TCE and the progressive accumulation of dissolved TCE in the solvent during the sampling process. Accordingly, based on the air-solvent partitioning coefficient, the sampling methodology (e.g. sampling rate, sampling duration, amount of solvent) and the final TCE concentration in the solvent, the concentration of TCE in the gas phase prevailing during the sampling event can be determined. Moreover, the possibility to analyse for TCE concentration in the solvent after sampling (or other targeted VOCs) allows the field deployment of the sampling method

  6. Pyrolysis compound specific isotopic analysis (δ13C and δD Py-CSIA) of soil organic matter size fractions under four vegetation covers. (United States)

    Jiménez-Morillo, Nicasio T.; González-Vila, Francisco J.; Almendros, Gonzalo; De la Rosa, José M.; González-Pérez, José A.


    A chemical characterization of soil organic matter (SOM) under different ground cover from a Mediterranean climate (Doñana National Park, Andalusia, Spain) is approached using bulk δ15N, δ13C, δ18O and δD isotopic analysis (C/TC-IRMS) and δ13C and δD pyrolysis compound specific isotopic analysis (Py-CSIA: Py-GC-C/TC-IRMS). Soil samples were collected in sandy soils, Arenosols (WRB 2006) from the Doñana National Park (SW Spain) under different vegetation cover: cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Two size fractions; coarse (C: 1-2 mm) and fine (F: biological reworking with a higher microbiological activity fixing the lighter isotope in the soil fine organic fractions. It is known that lipid hydrogen is deuterium depleted relative to bulk organic hydrogen (Smith and Epstein, 1970). In line with this, in our study the lipid derived compounds had the largest deuterium depleted signature with a difference between bulk and lipid δD values was c. -35‰. This fractionation was highest in Pine (PP) and Rockrose (HH). The combination of traditional techniques for the study of SOM i.e. Py-GC/MS and IRMS, with new hyphenated analytical pyrolysis techniques i.e. Py-CSIA opens new possibilities and windows of information in SOM research. Our findings points to the occurrence of more or less complex processes that affects SOM chemical characteristics; whereas the coarse fraction resembles the chemical structure of the above vegetation, this SOM "memory" is less defined in the fine fractions, probably due to biologically mediated chemical conversions, additions and selective preservation of refractory chemical structures. SOM bulk IRMS and Py-CSIA are also informative about relevant plant physiological processes, OM sources and OM evolution status. Acknowledgments: N.T Jiménez-Morillo is funded by a FPI research grant (BES-2013-062573). Dr. J.M. de la Rosa is the recipient

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

    CERN Document Server

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


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

  8. Carbon sources in suspended particles and surface sediments from the Beaufort Sea revealed by molecular lipid biomarkers and compound-specific isotope analysis


    I. Tolosa; S. Fiorini; B. Gasser; J. Martín; J. C. Miquel


    Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids) and compound-specific isotope analysis of suspended particulate organic matter (SPM) and surface sediments of the Mackenzie Shelf and slope (southeast Beaufort Sea, Arctic Ocean) were studied in summer 2009. The concentrations of the molecular lipid markers, characteristic of known organic matter sources, were grouped and used as proxies to evaluate the relative importance of fresh algal, detrital a...

  9. Modelling stable water isotopes: Status and perspectives

    Directory of Open Access Journals (Sweden)

    Werner M.


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

  10. physico-chemical and stable isotopes

    African Journals Online (AJOL)

    This paper details the mineralogical, chemical and stable isotope abundances of calcrete in the Letlhakeng fossil valley. The stable isotope abundances (O and C) of calcretes yielded some values which were tested against the nature of the calcretes – pedogenic or groundwater type. The Kgalagadi (Kalahari) is a vast ...

  11. Metabolism of microbial communities in the environment : A compound-specific stable hydrogen isotope approach

    NARCIS (Netherlands)

    Heinzelmann, S.M.


    Microorganisms are key players in all elemental cycles, their metabolic activity and potential impacts the environment on a local and global scale. In order to understand this significant role in the environment, microbial communities, their diversity and metabolic activity have to be studied in

  12. Authenticity of aroma components Enantiomeric separation and compound specific stable isotope analysis

    DEFF Research Database (Denmark)

    Hansen, Anne-Mette Sølvbjerg

    The word “authenticity” is increasingly used in the marketing of food products. A product can be marketed claiming its authenticity such as containing only natural ingredients or originating from a special location produced using local traditional production methods. Within the area of food...... ingredients a problem with authenticity of aroma compounds has occurred, because natural aromas are wholly or partly replaced with synthetic ones. This is a large economic problem, since natural aromas are often more expensive than artificial ones. Furthermore, the European Union has legal requirements...... necessary to develop new methods able to verify whether the authenticity of the food products is in agreement with the labelling. Some aroma compounds are chiral, meaning that they can exist as two enantiomers with different spatial orientation. Synthetic aroma compounds will consist of almost equal amounts...

  13. Reconstruction of past changes in ocean salinity - a compound specific stable hydrogen isotope approach

    NARCIS (Netherlands)

    Kasper, S.


    The extent of the general warming related to increasing anthropogenic CO2 emission andits implications for the global climate system are currently under heavy debate. In particular theextrapolation of long term climatic trends relies on complex climate models for the interactionbetween the

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

    NARCIS (Netherlands)

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


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

  15. Stable isotope labeling methods for DNA. (United States)

    Nelissen, Frank H T; Tessari, Marco; Wijmenga, Sybren S; Heus, Hans A


    NMR is a powerful method for studying proteins and nucleic acids in solution. The study of nucleic acids by NMR is far more challenging than for proteins, which is mainly due to the limited number of building blocks and unfavorable spectral properties. For NMR studies of DNA molecules, (site specific) isotope enrichment is required to facilitate specific NMR experiments and applications. Here, we provide a comprehensive review of isotope-labeling strategies for obtaining stable isotope labeled DNA as well as specifically stable isotope labeled building blocks required for enzymatic DNA synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Resolving the bulk δ 15N values of ancient human and animal bone collagen via compound-specific nitrogen isotope analysis of constituent amino acids (United States)

    Styring, Amy K.; Sealy, Judith C.; Evershed, Richard P.


    the biosynthetic pathway of threonine and the other amino acids. The δ 15N value of phenylalanine does not change significantly with trophic level, reflecting its conservative nature as an essential amino acid, and thus represents the isotopic composition of the nitrogen at the base of the food web. Δ 15N Glu-Phe values in particular are shown to reflect trophic level nitrogen sources within a food web. In relation to the reconstruction of ancient human diet the contribution of marine and terrestrial protein are strongly reflected in Δ 15N Glu-Phe values. Differences in nitrogen metabolism are also shown to have an influence upon individual amino acid δ 15N values with Δ 15N Glu-Phe values emphasising differences between the different physiological adaptations. The latter is demonstrated in tortoises, which can excrete nitrogen in the form of uric acid and urea and display negative Δ 15N Glu-Phe values whereas those for marine and terrestrial mammals are positive. The findings amplify the potential advantages of compound-specific nitrogen isotope analysis in the study of nitrogen flow within food webs and in the reconstruction of past human diets.

  17. Trophodynamics and functional feeding groups of North Sea fauna: a combined stable isotope and fatty acid approach

    NARCIS (Netherlands)

    Kürten, B.; Frutos, I.; Struck, U.; Painting, S.J.; Polunin, N.V.C.; Middelburg, J.J.


    The trophodynamics of pelagic and benthic animals of the North Sea, North Atlantic shelf, were assessed using stable isotope analysis (SIA) of natural abundance carbon and nitrogen isotopes, lipid fingerprinting and compound-specific SIA (CSIA) of phospholipid-derived fatty acids (PLFAs).

  18. Trophodynamics and functional feeding groups of North Sea fauna: a combined stable isotope and fatty acid approach

    NARCIS (Netherlands)

    Kürten, B.; Frutos, I.; Struck, U.; Painting, S.J.; Polunin, N.V.C.; Middelburg, J.J.

    The trophodynamics of pelagic and benthic animals of the North Sea, North Atlantic shelf, were assessed using stable isotope analysis (SIA) of natural abundance carbon and nitrogen isotopes, lipid fingerprinting and compound-specific SIA (CSIA) of phospholipid-derived fatty acids (PLFAs).

  19. Allan Hills Stable Water Isotopes, Version 1 (United States)

    National Aeronautics and Space Administration — This data set includes stable water isotope values at 10 m resolution along an approximately 5 km transect through the main icefield of the Allan Hills Blue Ice...

  20. Reconstructing hydroclimatic variations using compound-specific hydrogen isotope analysis of biomarkers from a maar lake in the Central Highlands, Vietnam (United States)

    Doiron, Kelsey; Stevens, Lora; Sauer, Peter


    Monsoonal variation in Southeast Asia affects a significant portion of the global population, but knowledge regarding response of the monsoon system to changing boundary conditions is limited. The paleoclimatic tool of compound-specific isotope analysis(CSIA) provides the ability to reconstruct past precipitation using a diverse set of biomarkers preserved in the sedimentary record. Limited proxies in tropical southeast Asia and difficult site access have led to a deficit in paleoclimate records. Ia M'He (14˚ 10'45" N, 107˚ 52' E) is a shallow volcanic crater (maar) lake, approximately 57 ha, located in the Central Highlands of Vietnam. Precipitation in the Central Highlands is sensitive to reorganizations of major climatic features, such as the migration of the ITCZ and the coupled Indo-Asian monsoon, ENSO and related shifts in the Pacific Walker Circulation and typhoon frequency. To examine this complex behavior, this pilot study aims to provide a 500-year record of effective moisture inferred from CSIA of hydrogen isotopes on biomarkers. Carbon/nitrogen ratios and carbon isotope ratios indicate that bulk organic matter is a combination of algae and C3 vegetation, offering the potential to use compound-specific hydrogen isotopes of aquatic and terrestrial organic matter in tandem. Preliminary analysis of the core shows dominant alkane chain lengths of C27 and C29, associated with terrestrial plant leaf waxes. The hydrogen isotope ratios of the plant wax components provide a proxy for paleo precipitation in a region where rainfall and droughts heavily influence population dynamics and create social discord. The CSIA record is expected to correlate with records from northern Vietnam, the South China Sea and Indonesia, with greater precipitation during the Little Ice Age. The degree to which evaporative modification of lake water (i.e., seasonal drying) occurs will be estimated by comparing the terrestrial CSIA values indicative of meteoric water with aquatic CSIA

  1. Compound Specific Hydrogen Isotope Composition of Type II and III Kerogen Extracted by Pyrolysis-GC-MS-IRMS (United States)

    Socki, Richard A.; Pernia, Denet; Evans, Michael; Fu, Qi; Bissada, Kadry K.; Curiale, Joseph A.; Niles, Paul B.


    The use of Hydrogen (H) isotopes in understanding oil and gas resource plays is in its infancy. Described here is a technique for H isotope analysis of organic compounds pyrolyzed from oil and gas shale-derived kerogen. Application of this technique will progress our understanding. This work complements that of Pernia et al. (2013, this meeting) by providing a novel method for the H isotope analysis of specific compounds in the characterization of kerogen extracted by analytically diverse techniques. Hydrogen isotope analyses were carried out entirely "on-line" utilizing a CDS 5000 Pyroprobe connected to a Thermo Trace GC Ultra interfaced with a Thermo MAT 253 IRMS. Also, a split of GC-separated products was sent to a DSQ II quadrupole MS to make semi-quantitative compositional measurements of the extracted compounds. Kerogen samples from five different basins (type II and III) were dehydrated (heated to 80 C overnight in vacuum) and analyzed for their H isotope compositions by Pyrolysis-GC-MS-TC-IRMS. This technique takes pyrolysis products separated via GC and reacts them in a high temperature conversion furnace (1450 C) which quantitatively forms H2, following a modified method of Burgoyne and Hayes, (1998, Anal. Chem., 70, 5136-5141). Samples ranging from approximately 0.5 to 1.0mg in size, were pyrolyzed at 800 C for 30s. Compounds were separated on a Poraplot Q GC column. Hydrogen isotope data from all kerogen samples typically show enrichment in D from low to high molecular weight compounds. Water (H2O) average deltaD = -215.2 (V-SMOW), ranging from -271.8 for the Marcellus Shale to -51.9 for the Polish Shale. Higher molecular weight compounds like toluene (C7H8) have an average deltaD of -89.7 0/00, ranging from -156.0 for the Barnett Shale to -50.0 for the Monterey Shale. We interpret these data as representative of potential H isotope exchange between hydrocarbons and sediment pore water during formation within each basin. Since hydrocarbon H isotopes

  2. Stable isotopes in Lithuanian bioarcheological material (United States)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas


    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

  3. 37Cl-compound specific isotope analysis and assessment of functional genes for monitoring monochlorobenzene (MCB) biodegradation under aerobic conditions. (United States)

    Marchesi, Massimo; Alberti, Luca; Shouakar-Stash, Orfan; Pietrini, Ilaria; de Ferra, Francesca; Carpani, Giovanna; Aravena, Ramon; Franzetti, Andrea; Stella, Tatiana


    A laboratory approach was adopted in this study to explore the potential of 37Cl-CSIA in combination with 13C-CSIA and Biological Molecular Tools (BMTs) to estimate the occurrence of monochloroenzene (MCB) aerobic biodegradation. A new analytical method for 37Cl-CSIA of MCB was developed in this study. This methodology using a GC-IRMS allowed to determine δ37Cl values within an internal error of ±0.3‰. Samples from a heavily MCB contaminated site were collected and MCB aerobic biodegradation microcosms with indigenous cultures in natural and enhanced conditions were set up. The microcosms data show a negligible fractionation for 13C associated to MCB mass decrease of >95% over the incubation time. Conversely, an enrichment factor of -0.6±0.1‰ was estimated for 37Cl, which is a reflection of a secondary isotope effect. Moreover, the dual isotope approach showed a pattern for aerobic degradation which differ from the theoretical trend for reductive dehalogenation. Quantitative Polymerase Chain Reaction (qPCR) results showed a significant increase in todC gene copy number with respect to its initial levels for both natural attenuation and biostimulated microcosms, suggesting its involvement in the MCB aerobic degradation, whereas phe gene copy number increased only in the biostimulated ones. Indeed, 37Cl fractionation in combination with the dual carbon‑chlorine isotope approach and the todC gene copy number represent valuable indicators for a qualitative assessment of MCB aerobic biodegradation in the field. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Stable isotope dilution assays in mycotoxin analysis. (United States)

    Rychlik, Michael; Asam, Stefan


    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis.

  5. Stable isotope dilution assays in mycotoxin analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rychlik, Michael; Asam, Stefan [Universitaet Muenchen, Lehrstuhl fuer Lebensmittelchemie der Technischen, Garching (Germany)


    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis. (orig.)

  6. Stable water isotopes in the MITgcm (United States)

    Völpel, Rike; Paul, André; Krandick, Annegret; Mulitza, Stefan; Schulz, Michael


    We present the first results of the implementation of stable water isotopes in the Massachusetts Institute of Technology general circulation model (MITgcm). The model is forced with the isotopic content of precipitation and water vapor from an atmospheric general circulation model (NCAR IsoCAM), while the fractionation during evaporation is treated explicitly in the MITgcm. Results of the equilibrium simulation under pre-industrial conditions are compared to observational data and measurements of plankton tow records (the oxygen isotopic composition of planktic foraminiferal calcite). The broad patterns and magnitude of the stable water isotopes in annual mean seawater are well captured in the model, both at the sea surface as well as in the deep ocean. However, the surface water in the Arctic Ocean is not depleted enough, due to the absence of highly depleted precipitation and snowfall. A model-data mismatch is also recognizable in the isotopic composition of the seawater-salinity relationship in midlatitudes that is mainly caused by the coarse grid resolution. Deep-ocean characteristics of the vertical water mass distribution in the Atlantic Ocean closely resemble observational data. The reconstructed δ18Oc at the sea surface shows a good agreement with measurements. However, the model-data fit is weaker when individual species are considered and deviations are most likely attributable to the habitat depth of the foraminifera. Overall, the newly developed stable water isotope package opens wide prospects for long-term simulations in a paleoclimatic context.

  7. Stable water isotopes in the MITgcm

    Directory of Open Access Journals (Sweden)

    R. Völpel


    Full Text Available We present the first results of the implementation of stable water isotopes in the Massachusetts Institute of Technology general circulation model (MITgcm. The model is forced with the isotopic content of precipitation and water vapor from an atmospheric general circulation model (NCAR IsoCAM, while the fractionation during evaporation is treated explicitly in the MITgcm. Results of the equilibrium simulation under pre-industrial conditions are compared to observational data and measurements of plankton tow records (the oxygen isotopic composition of planktic foraminiferal calcite. The broad patterns and magnitude of the stable water isotopes in annual mean seawater are well captured in the model, both at the sea surface as well as in the deep ocean. However, the surface water in the Arctic Ocean is not depleted enough, due to the absence of highly depleted precipitation and snowfall. A model–data mismatch is also recognizable in the isotopic composition of the seawater–salinity relationship in midlatitudes that is mainly caused by the coarse grid resolution. Deep-ocean characteristics of the vertical water mass distribution in the Atlantic Ocean closely resemble observational data. The reconstructed δ18Oc at the sea surface shows a good agreement with measurements. However, the model–data fit is weaker when individual species are considered and deviations are most likely attributable to the habitat depth of the foraminifera. Overall, the newly developed stable water isotope package opens wide prospects for long-term simulations in a paleoclimatic context.

  8. Stable isotope analysis of dynamic lipidomics. (United States)

    Brandsma, Joost; Bailey, Andrew P; Koster, Grielof; Gould, Alex P; Postle, Anthony D


    Metabolic pathway flux is a fundamental element of biological activity, which can be quantified using a variety of mass spectrometric techniques to monitor incorporation of stable isotope-labelled substrates into metabolic products. This article contrasts developments in electrospray ionisation mass spectrometry (ESI-MS) for the measurement of lipid metabolism with more established gas chromatography mass spectrometry and isotope ratio mass spectrometry methodologies. ESI-MS combined with diagnostic tandem MS/MS scans permits the sensitive and specific analysis of stable isotope-labelled substrates into intact lipid molecular species without the requirement for lipid hydrolysis and derivatisation. Such dynamic lipidomic methodologies using non-toxic stable isotopes can be readily applied to quantify lipid metabolic fluxes in clinical and metabolic studies in vivo. However, a significant current limitation is the absence of appropriate software to generate kinetic models of substrate incorporation into multiple products in the time domain. Finally, we discuss the future potential of stable isotope-mass spectrometry imaging to quantify the location as well as the extent of lipid synthesis. This article is part of a Special Issue entitled: BBALIP_Lipidomics Opinion Articles edited by Sepp Kohlwein. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Monitoring of the aerobe biodegradation of chlorinated organic solvents by stable isotope analysis (United States)

    Horváth, Anikó; Futó, István; Palcsu, László


    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.

  10. Developing stable isotopic records from organic material preserved in speleothems (United States)

    Blyth, A.; Baker, A.


    Speleothems form excellent archives of environmental change as they are easy to date and preserve multiple environmental records. However, although the stable isotopic composition of speleothem calcite is well characterised, the isotopic composition of organic matter in speleothems has not been investigated in-depth. The approach has considerable potential value in providing isotopic records directly linked to the overlying ecosystem. For stable carbon isotopes, this will provide records independent of the calcite signal, and enable identification of the local primary controls (vegetation type, climate, soil conditions). However, the detailed measurement of isotopic records in speleothem organic matter is hindered by methodological constraints, including extraction of sufficient material, and recovery without adding carbon contamination. Here we present results from a number of methodological techniques and discuss which show most potential for future palaeoenvironmental work. Isotopic records in organic matter can be divided into two main types - analyses of the bulk organic fraction, and compound-specific analyses of molecules of interest (e.g. plant waxes, bacterial lipids etc.). From the point of view of sample size, bulk analysis is the most amenable. Our work shows that TOC in stalagmites can be as low as <0.1 mg/g calcite. However, this is still sufficient to produce bulk organic signals at a sample size of between 100 and 500 mg of calcite powder, which provides a workable temporal resolution at a decadal-centennial scale on many samples. The main obstacle is the recovery of bulk organics without carbon contamination, but whilst avoiding excess acid salts which might damage the instrumentation. One method we propose is the use of an iTOC-CDRS analyser, which measures total organic carbon, and also 12C and 13C isotopes. The approach has the advantage of requiring minimal sample preparation, with drilled powders simply being dissolved in acid. The major

  11. C, Cl and H compound-specific isotope analysis to assess natural versus Fe(0) barrier-induced degradation of chlorinated ethenes at a contaminated site

    Energy Technology Data Exchange (ETDEWEB)

    Audí-Miró, Carme, E-mail: [Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), Martí Franquès s/n, 08028, Barcelona (Spain); Cretnik, Stefan [Institute of Groundwater Ecology, Helmholtz Zentrum München-National Research Center for Environmental Health, Ingolstädter Landstrasse 1, D-85764 Neuherberg (Germany); Torrentó, Clara; Rosell, Mònica [Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), Martí Franquès s/n, 08028, Barcelona (Spain); Shouakar-Stash, Orfan [Department of Earth & Environmental Sciences, 200 University Ave. W, N2L 3G1 Waterloo, Ontario (Canada); Otero, Neus [Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), Martí Franquès s/n, 08028, Barcelona (Spain); Palau, Jordi [Université de Neuchâtel, CHYN - Centre d' Hydrogéologie, Rue Emile-Argand 11, CH-2000 Neuchâtel (Switzerland); and others


    Highlights: • {sup 13}C to evaluate natural chlorinated ethenes biodegradation. • {sup 13}C to evaluate the efficiency of a zero-valent iron-permeable reactive barrier. • {sup 13}C-{sup 37}Cl to discriminate biotic from abiotic degradation of cis-dichloroethene. • {sup 13}C-{sup 37}Cl-{sup 2}H of cis-DCE and TCE to elucidate different contaminant sources. - Abstract: Compound-specific isotopic analysis of multiple elements (C, Cl, H) was tested to better assess the effect of a zero-valent iron-permeable reactive barrier (ZVI-PRB) installation at a site contaminated with tetrachloroethene (PCE) and trichloroethene (TCE). The focus was on (1) using {sup 13}C to evaluate natural chlorinated ethene biodegradation and the ZVI-PRB efficiency; (2) using dual element {sup 13}C-{sup 37}Cl isotopic analysis to distinguish biotic from abiotic degradation of cis-dichloroethene (cis-DCE); and (3) using {sup 13}C-{sup 37}Cl-{sup 2}H isotopic analysis of cis-DCE and TCE to elucidate different contaminant sources. Both biodegradation and degradation by ZVI-PRB were indicated by the metabolites that were detected and the {sup 13}C data, with a quantitative estimate of the ZVI-PRB efficiency of less than 10% for PCE. Dual element {sup 13}C-{sup 37}Cl isotopic plots confirmed that biodegradation was the main process at the site including the ZVI-PRB area. Based on the carbon isotope data, approximately 45% and 71% of PCE and TCE, respectively, were estimated to be removed by biodegradation. {sup 2}H combined with {sup 13}C and {sup 37}Cl seems to have identified two discrete sources contributing to the contaminant plume, indicating the potential of δ{sup 2}H to discriminate whether a compound is of industrial origin, or whether a compound is formed as a daughter product during degradation.

  12. Heavy Stable Isotopes: From Exceptional to Expected (United States)

    Anbar, A.


    Less than a decade ago, the stable isotope geochemistry of transition metals and other "heavy" elements was a highly specialized niche confined to a few seemingly exceptional elements. This situation was transformed by the development and refinement of MC-ICP-MS techniques, particularly in the last five years. Measurable stable isotope variations turn out to be ubiquitous across the periodic table, from Li to Hg. It is now safe to assume that the isotopic composition of any element with two or more stable isotopes is measurably variable. What was once exceptional is now expected. Among the first of these new systems to be explored were Fe and Mo isotopes. A number of lessons emerging from this work can be applied to the development of other isotope systems. Most important is that initial expectations are often wrong. For example, based on their environmental chemistries it was expected that redox reactions should produce some of the largest isotope effects for both elements. In the case of Fe, theoretical and experimental studies converge to convincingly indicate that a fractionation of ~ 1.5 ‰/amu occurs between Fe(III) and Fe(II) aquo complexes at equilibrium (e.g., Welch et al., 2003; Anbar et al., 2005). Consistent with these findings, most natural variations of are < 1.5 ‰/amu (e.g., Johnson et al., 2004). This redox-related fractionation is at the heart of emerging interpretations of variations in the isotopic composition of Fe and their application to understanding ancient ocean redox (e.g., Dauphas et al., 2004; Rouxel et al., 2005). In contrast, Mo isotope variations turn out to be controlled only indirectly by redox conditions. Instead, one of the most important Mo isotope effects in the environment appears to be a fractionation of ~ 1 ‰/amu during adsorption of Mo to Mn-oxides (Barling et al., 2001; Siebert et al., 2003). This fractionation has been reproduced in the laboratory (Barling and Anbar, 2004) and appears to be an equilibrium isotope

  13. Compound-specific isotopic fractionation patterns suggest different carbon metabolisms among Chloroflexus-like bacteria in hot-spring microbial mats. (United States)

    van der Meer, Marcel T J; Schouten, Stefan; Sinninghe Damsté, Jaap S; de Leeuw, Jan W; Ward, David M


    Stable carbon isotope fractionations between dissolved inorganic carbon and lipid biomarkers suggest photoautotrophy by Chloroflexus-like organisms in sulfidic and nonsulfidic Yellowstone hot springs. Where co-occurring, cyanobacteria appear to cross-feed Chloroflexus-like organisms supporting photoheterotrophy as well, although the relatively small 13C fractionation associated with cyanobacterial sugar biosynthesis may sometimes obscure this process.

  14. Compound-Specific Isotopic Fractionation Patterns Suggest Different Carbon Metabolisms among Chloroflexus-Like Bacteria in Hot-Spring Microbial Mats† (United States)

    van der Meer, Marcel T. J.; Schouten, Stefan; Sinninghe Damsté, Jaap S.; de Leeuw, Jan W.; Ward, David M.


    Stable carbon isotope fractionations between dissolved inorganic carbon and lipid biomarkers suggest photoautotrophy by Chloroflexus-like organisms in sulfidic and nonsulfidic Yellowstone hot springs. Where co-occurring, cyanobacteria appear to cross-feed Chloroflexus-like organisms supporting photoheterotrophy as well, although the relatively small 13C fractionation associated with cyanobacterial sugar biosynthesis may sometimes obscure this process. PMID:14532055

  15. The production of stable isotopes in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Urgel, M.; Iglesias, J.; Casas, J.; Saviron, J. M.; Quintanilla, M.


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

  16. Temporal dynamics in a shallow coastal benthic food web: Insights from fatty acid biomarkers and their stable isotopes

    NARCIS (Netherlands)

    Braeckman, U.; Provoost, P.; Sabbe, K.; Soetaert, K.; Middelburg, J.J.; Vincx, M.; Vanaverbeke, J.


    We investigated the temporal variation of pelagic and benthic food sources in the diet of benthic taxa at a depositional site in the Southern Bight of the North Sea by means of fatty acid (FA) biomarkers and compound-specific stable isotope analysis (CSIA). The taxa were the non-selective deposit

  17. Tungsten Stable Isotope Compositions of Ferromanganese Crusts (United States)

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


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

  18. Stable Isotope Spectroscopy for Diagnostic Medicine (United States)

    Murnick, D. E.


    Isotopic tracers have been used in medical research for more than fifty years. Radioactive isotopes have been most used because of the high detection efficiencies possible. With increased awareness of the effects of low level radiation and radioactive waste management problems, the need for safe non radioactive tracers has become apparent. Rare stable isotopes of biologically active elements can be used for metabolic and pharmacokinetic studies provided that both sufficient detection sensitivity can be achieved and reliable cost effective instruments can be developed. High resolution optical spectroscopic methods which can determine isotopic ratios with high precision and accuracy are viable for research and clinical use. The study of 13C/12C ratios in CO2 for breath test diagnostics will be described in detail. Using the laser optogalvonic effect with isotopic lasers a specific medical diagnostic for h-pylori infection, has recently received FDA approval. Opportunities exist to study D/H ratios in water and 18O/16O ratios in CO2 and water for basic metabolism diagnostics and 15N/14N ratios in urine for liver function and related studies.

  19. Stable isotope analysis in primatology: a critical review. (United States)

    Sandberg, Paul A; Loudon, James E; Sponheimer, Matt


    Stable isotope analysis has become an important tool in ecology over the last 25 years. A wealth of ecological information is stored in animal tissues in the relative abundances of the stable isotopes of several elements, particularly carbon and nitrogen, because these isotopes navigate through ecological processes in predictable ways. Stable carbon and nitrogen isotopes have been measured in most primate taxonomic groups and have yielded information about dietary content, dietary variability, and habitat use. Stable isotopes have recently proven useful for addressing more fine-grained questions about niche dynamics and anthropogenic effects on feeding ecology. Here, we discuss stable carbon and nitrogen isotope systematics and critically review the published stable carbon and nitrogen isotope data for modern primates with a focus on the problems and prospects for future stable isotope applications in primatology. © 2012 Wiley Periodicals, Inc.

  20. The Importance of Zostera marina to a Local Food Web Based on the Analysis of Compound Specific Isotopes in Maquoit Bay, Gulf of Maine (United States)

    Doolittle, H. A.; Johnson, B. J.; Ambrose, W. G.; Locke, W.; Harris, C. M.


    Zostera marina (also known as eelgrass) is an important primary producer in near shore ecosystems in the Gulf of Maine, providing both habitat and nutrients for a variety of organisms (e.g., crustaceans, polychaetes, gastropods, and fish). The purpose of this study is to use compound specific δ13C analyses of essential amino acids to determine the degree to which organic matter derived from isotopically distinct primary producers (e.g., eelgrass, phytoplankton, and epiphytic algae) contribute to the diets of snails, shrimp, and fish in an eelgrass system in Casco Bay. Maquoit Bay, located in northwestern Casco Bay, in the Gulf of Maine, is a shallow estuarine system that is characterized by silt and clay sized sediments and the presence of extensive eelgrass beds. Amino acid concentrations and δ13C compositions were determined for a variety of sample-types collected in July-August, 2010, from three sites in the study area, including muscle tissue from Tautogolabrus adspersus (cunner), Gasterosteus aculeatus (3-spined stickleback), Nassarius obsoletus (snail), and Mysis spp. (shrimp), seston (i.e., phytoplankton), Z. marina, and epiphytic algae. TFAA amino acid derivatives of the total hydrolyzate were analyzed by GC-FID for amino acid concentration, and by GC-c-IRMS- for carbon isotope composition. Muscle tissue was dominated by glutamic and aspartic acids, and leucine, whereas Zostera marina was dominated by aspartic and glutamic acids, and proline. Phenylalanine and leucine in Z. marina are approximately 10 ‰ enriched in 13C relative to these same amino acids in the seston. The carbon isotope values of these essential amino acids are significantly more enriched in 13C for N. obsoletus than for T. adspersus, G. aculeatus, and Mysis spp. These data suggest that organic matter derived from Z. marina and/or epiphytic algae is more important in the diets of N. obsoletus, and organic matter derived from seston is more important for the diets of T. adspersus, G

  1. Stable isotopic analyses in paleoclimatic reconstruction

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  2. Geochemistry of the stable isotopes of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Douthitt, C.B. (California Inst. of Tech., Pasadena (USA). Div. of Geological and Planetary Sciences)


    One hundred thirty two new measurements of the relative abundances of the stable isotopes of silicon in terrestrial materials are presented. The total variation of delta/sup 30/Si found is 6.2 parts per thousand, centered on the mean of terrestrial mafic and ultramafic igneous rocks, delta/sup 30/Si = -0.4 parts per thousand. Igneous rocks show limited variation; coexisting minerals exhibit small, systematic silicon isotopic fractionations that are roughly 1/3 the magnitude of concomitant oxygen isotopic fractionations at 1150/sup 0/C. In both igneous minerals and rocks, delta/sup 30/Si shows a positive correlation with silicon content, as does delta/sup 18/O. Opal from both sponge spicules and sinters is light, with delta/sup 30/Si = -2.3 and -1.4 parts per thousand respectively. Large delta/sup 30/Si values of both positive and negative sign are reported for the first time from clay minerals, opaline phytoliths, and authigenic quartz. All highly fractionated samples were precipitated from solution at low temperatures; however, aqueous silicon is not measurably fractionated relative to quartz at equilibrium. A kinetic isotope fractionation of approximately 3.5 parts per thousand is postulated to occur during the low temperature precipitation of opal and, possibly, poorly ordered phyllosilicates, with the silicate phase being enriched in /sup 28/Si. This fractionation, coupled with a Rayleigh precipitation model, is capable of explaining most non-magmatic delta/sup 30/Si variations.

  3. Linking flow cytometric cell sorting and compound-specific 13C-analysis to determine population-specific isotopic signatures and growth rates in cyanobacteria-dominated lake plankton

    NARCIS (Netherlands)

    Pel, R.; Floris, V.; Gons, H.J.; Hoogveld, H.L.


    A novel methodology was applied to determine the 13C signatures of natural cyanobacterial and algal populations by combined compound-specific isotope ratio mass spectrometry and pyrolytic methylation-gas chromatography (Py-GC-IRMS) of the fatty acids released from phytoplankton fractions collected

  4. Production and application of stable enriched isotopes in the USSR

    Energy Technology Data Exchange (ETDEWEB)

    Kudziev, A.G. (Institute of Stable Isotopes, Tbilisi (USSR))


    At present stable enriched isotopes are contributing essentially to the progress in many fields of sciences and national economy. The application of isotopically modified compounds and materials allowed to obtain a number of remarkable scientific results and initiated developments of great applied significance. This presentation will survey status and development activities involving enriched stable isotopes in the USSR. (orig.).

  5. The stable isotope fingerprinting technique for agricultural pesticide (United States)

    Suto, N.; Kawashima, H.


    The compound specific isotope analysis (CSIA) is nowadays an important and powerful tool in geochemical, environmental, and forensics field. In particular, the stable isotope ratio of pesticide is applied to biological process and reaction in the soil and distribution channel as forensics science. The aim of this study is to measure the stable isotope ratios of pesticide using various analytical methodologies, GC/IRMS, EA/IRMS, and LC/IRMS under high accuracy and precision. Therefore, these methods seemed to be important knowledge as geological field. In particular case, we present the method to measure carbon isotope ratio of nine malathion emulsion pesticides using GC/IRMS with cryo-focusing system to identify the source. In December 2013, food poisoning occurred after eating frozen dumplings (i.e., pizza and chicken nuggets) in Japan. There was a very high concentration, maximum value 15,000ppm, of malathion (diethyl (dimethoxythiophosphorylthio) succinate) in products. This incident was caused by an employee of process, and threatened the food safety. We analyzed the δ13C of malathion ranged from -30.63‰ to -29.54‰ (S.D. 0.10‰), the differences less than 1.0‰. All malathion emulsion sold in Japan are imported from Cheminova India Lat., Denmark to Sumitomo Chemical Co. Ltd., Japan. After that, Japanese each manufacture buy from Sumitomo Chemical Co. Ltd. And blended malathion and organic solvent (ethylbenzene and xylene). Therefore, ethylbenzene and xylene may be important tool as source identification. We measured the δ13C of ethylbenzene and m-,p-xylene, too. As the results, the δ13C of ethylbenzene and m-,p-xylene ranged from -28.20‰ to -20.84‰ (S.D. 0.16‰), -28.69‰ to -25.15‰ (S.D. 0.13‰), respectively. The δ13C of ethylbenzene and m-,p-xylene can be identified manufacture, although the δ13C of malathion indicated same value. In addition, we measured five pesticides (acephate, acetamiprid, glufosinate, glyphosate, and oxamyl) using

  6. Comprehensive analytical methodology to determine hydrocarbons in marine waters using extraction disks coupled to glass fiber filters and compound-specific isotope analyses. (United States)

    Ternon, Eva; Tolosa, Imma


    Solid-phase extraction of both aliphatic (AHs) and aromatic polycyclic hydrocarbons (PAHs) from seawater samples was evaluated using a GFF filter stacked upon an octadecyl bonded silica (C18) disk. Stable-isotope measurements were developed on hydrocarbons extracted from both GFF and C18-disks in order to characterize the source of hydrocarbons. A clear partition of hydrocarbon compounds between the dissolved and the particulate phase was highlighted. PAHs showed a higher affinity with the dissolved phase (recoveries efficiency of 48-71%) whereas AHs presented strong affinity with the particulate phase (up to 76% of extraction efficiency). Medium volumes of seawater samples were tested and no breakthrough was observed for a 5L sample. Isotopic fractionation was investigated within all analytical steps but none was evidenced. This method has been applied to harbor seawater samples and very low AH and PAH concentrations were achieved. Due to the low concentration levels of hydrocarbons in the samples, the source of hydrocarbons was determined by molecular indices rather than isotopic measurements and a pyrolytic origin was evidenced. The aliphatic profile also revealed the presence of long-chain linear alkylbenzenes (LABs). The methodology presented here would better fit to polluted coastal environments affected by recent oil spills. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Compound-specific hydrogen isotope analysis of fluorine-, chlorine-, bromine- and iodine-bearing organics using gas chromatography-chromium-based high-temperature conversion (Cr/HTC) isotope ratio mass spectrometry. (United States)

    Renpenning, Julian; Schimmelmann, Arndt; Gehre, Matthias


    The conventional high-temperature conversion (HTC) approach towards hydrogen compound-specific isotope analysis (CSIA) of halogen-bearing (F, Cl, Br, I) organics suffers from incomplete H2 yields and associated hydrogen isotope fractionation due to generation of HF, HCl, HBr, and HI byproducts. Moreover, the traditional off-line combustion of highly halogenated compounds results in incomplete recovery of water as an intermediary compound for hydrogen isotope ratio mass spectrometry (IRMS), and hence also leads to isotope fractionation. This study presents an optimized chromium-based high-temperature conversion (Cr/HTC) approach for hydrogen CSIA of various fluorinated, chlorinated, brominated and iodinated organic compounds. The Cr/HTC approach is fast, economical, and not affected by low H2 yields and associated isotope fractionation. The performance of the modified gas chromatography/chromium-based high-temperature conversion (GC-Cr/HTC) system was monitored and optimized using an ion trap mass spectrometer. Quantitative conversion of organic hydrogen into H2 analyte gas was achieved for all halogen-bearing compounds. The corresponding accuracy of CSIA was validated using (i) manual dual-inlet (DI)-IRMS after off-line conversion into H2 , and (ii) elemental analyzer (EA)-Cr/HTC-IRMS (on-line conversion). The overall hydrogen isotope analysis of F-, Cl-, Br- and I-bearing organics via GC-Cr/HTC-IRMS achieved a precision σ ≤ 3 mUr and an accuracy within ±5 mUr along the VSMOW-SLAP scale compared with the measured isotope compositions resulting from both validation methods, off-line and on-line. The same analytical performance as for single-compound GC-Cr/HTC-IRMS was achieved compound-specifically for mixtures of halogenated organics following GC separation to baseline resolution. GC-Cr/HTC technology can be implemented in existing analytical equipment using commercially available materials to provide a versatile tool for hydrogen CSIA of halogenated and non

  8. Compound-specific chlorine isotope analysis: a comparison of gas chromatography/isotope ratio mass spectrometry and gas chromatography/quadrupole mass spectrometry methods in an interlaboratory study. (United States)

    Bernstein, Anat; Shouakar-Stash, Orfan; Ebert, Karin; Laskov, Christine; Hunkeler, Daniel; Jeannottat, Simon; Sakaguchi-Söder, Kaori; Laaks, Jens; Jochmann, Maik A; Cretnik, Stefan; Jager, Johannes; Haderlein, Stefan B; Schmidt, Torsten C; Aravena, Ramon; Elsner, Martin


    Chlorine isotope analysis of chlorinated hydrocarbons like trichloroethylene (TCE) is of emerging demand because these species are important environmental pollutants. Continuous flow analysis of noncombusted TCE molecules, either by gas chromatography/isotope ratio mass spectrometry (GC/IRMS) or by GC/quadrupole mass spectrometry (GC/qMS), was recently brought forward as innovative analytical solution. Despite early implementations, a benchmark for routine applications has been missing. This study systematically compared the performance of GC/qMS versus GC/IRMS in six laboratories involving eight different instruments (GC/IRMS, Isoprime and Thermo MAT-253; GC/qMS, Agilent 5973N, two Agilent 5975C, two Thermo DSQII, and one Thermo DSQI). Calibrations of (37)Cl/(35)Cl instrument data against the international SMOC scale (Standard Mean Ocean Chloride) deviated between instruments and over time. Therefore, at least two calibration standards are required to obtain true differences between samples. Amount dependency of δ(37)Cl was pronounced for some instruments, but could be eliminated by corrections, or by adjusting amplitudes of standards and samples. Precision decreased in the order GC/IRMS (1σ ≈ 0.1‰), to GC/qMS (1σ ≈ 0.2-0.5‰ for Agilent GC/qMS and 1σ ≈ 0.2-0.9‰ for Thermo GC/qMS). Nonetheless, δ(37)Cl values between laboratories showed good agreement when the same external standards were used. These results lend confidence to the methods and may serve as a benchmark for future applications. © 2011 American Chemical Society

  9. Assessing the Origins of Aliphatic Amines in the Murchison Meteorite from their Compound-Specific Carbon Isotopic Ratios and Enantiomeric Composition (United States)

    Aponte, Jose; Dworkin, Jason; Elsila, Jamie E.


    The study of meteoritic organic compounds provides a unique window into the chemical inventory of the early Solar System and prebiotic chemistry that may have been important for the origin of life on Earth. Multiple families of organic compounds have been extracted from the Murchison meteorite, which is one of the most thoroughly studied carbonaceous chondrites. The amino acids extracted from Murchison have been extensively analyzed, including measurements of non-terrestrial stable isotopic ratios and discoveries of L-enantiomeric excesses for alpha-dialkyl amino acids, notably isovaline. However, although the isotopic signatures of bulk amine-containing fractions have been measured, the isotopic ratios and enantiomeric composition of individual aliphatic amines, compounds that are chemically related to amino acids, remain unknown. Here, we report a novel method for the extraction, separation, identification and quantitation of aliphatic monoamines extracted from the Murchison meteorite. Our results show a complete suite of structural isomers, with a larger concentration of methylamine and ethylamine and decreasing amine concentrations with increasing carbon number. The carbon isotopic compositions of fourteen meteoritic aliphatic monoamines were measured, with delta C-13 values ranging from +21% to +129%, showing a decrease in C-13 with increasing carbon number, a relationship that may be consistent with the chain elongation mechanism under kinetic control previously proposed for meteoritic amino acids. We also found the enantiomeric composition of sec-butylamine, a structural analog to isovaline, was racemic within error, while the isovaline extracted from the same Murchison piece showed an L-enantiomeric excess of 9.7; this result suggested that processes leading to enantiomeric excess in the amino acid did not affect the amine. We used these collective data to assess the primordial synthetic origins of these meteoritic aliphatic amines and their potential

  10. Joint interpretation of enantiomer and stable isotope fractionation for chiral pesticides degradation. (United States)

    Jin, Biao; Rolle, Massimo


    Chiral pesticides are important contaminants affecting the health and functioning of aquatic systems. The combination of stable isotope and enantiomer analysis techniques has been recently proposed to better characterize the fate of these contaminants in natural and engineered settings. We introduce a modeling approach with the aim of unifying and integrating the interpretation of isotopic and enantiomeric fractionation. The model is based on the definition of enantiomer-specific isotopologues and jointly predicts the evolution of concentration, enantiomer fractionation, as well as changes in stable isotope ratios of different elements. The method allows evaluating different transformation pathways and was applied to investigate enzymatic degradation of dichlorprop (DCPP), enzymatic degradation of mecoprop methyl ester (MCPPM), and microbial degradation of α-hexachlorocyclohexane (α-HCH) by different bacterial strains and under different redox conditions. The model accurately reproduces the isotopic and enantiomeric data observed in previous experimental studies and precisely captures the dual-dimensional trends characterizing different reaction pathways. Furthermore, the model allows testing possible combinations of enantiomer analysis (EA), compound specific isotope analysis (CSIA), and enantiomer specific isotope analysis (ESIA) to identify and assess isotope and enantiomer selective reaction mechanisms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Stable isotope characterization of the Vermigliana catchment (United States)

    Chiogna, Gabriele; Santoni, Emilio; Camin, Federica; Tonon, Agostino; Majone, Bruno; Trenti, Alberto; Bellin, Alberto


    Characterizing the hydrological behavior of streams in small Alpine catchments spanning a wide range of elevations is a difficult task, often hampered by the intrinsic variability of streamwater sources. Stable isotope ratios of oxygen and hydrogen have been sampled monthly in order to determine the spatial and temporal hydrological behavior and the mean residence time of water in the Vermigliana catchment, North-Eastern Italy. This study aims at separating contributions to streamflow originating from Presena and Presanella glaciers, both exerting a strong control on the hydrologic budget of the study site. The isotopic signature of precipitation has been collected at two locations at different altitudes (1176 m a.s.l. and 2731 m a.s.l.), while stream water was sampled at 11 locations, 8 along the main course of the Vermigliana creek and 3 along the two tributaries of the Vermigliana creek: the Presanella and Presena creeks. Groundwater was sampled monthly in a single location, whilst the waters of two small lakes, Capanna Presena and Cantiere, both located in the proximity of the Presena glacier, were sampled during summer, when the sites were accessible. Isotope analysis evidenced that Presena and Presanella creeks are the main contributors to the Vermigliana creek. The contribution of the Presanella creek is 44% of the total flow at the confluence with the Vermigliana, while the contribution of the Presena creek rises to 75% of the total flow immediately after the confluence. The mean residence times computed for the Vermigliana and the tributaries vary between 7 and 5 months, respectively. This work allows us to investigate the main components in the hydrological cycle of the Vermigliana catchment and constitutes the basis for future modeling and climate change impact studies on this important Alpine catchment. The methodology can be exported to other sites with the aim to provide additional data, with respect to streamflow at the catchment outlet, to reduce

  12. Pygmy dipole resonance in stable Ca isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Tertychny, G. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Institute of Physics and Power Engineering, 249020 Obninsk (Russian Federation); Tselyaev, V. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Institute of Physics S.Petersburg University (Russian Federation); Kamerdzhiev, S. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Institute of Physics and Power Engineering, 249020 Obninsk (Russian Federation); Gruemmer, F. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Krewald, S. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Speth, J. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Litvinova, E. [Institute of Physics and Power Engineering, 249020 Obninsk (Russian Federation); Avdeenkov, A. [Institute of Physics and Power Engineering, 249020 Obninsk (Russian Federation); Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany)


    The properties of the low-lying electric dipole strength in the stable {sup 40}Ca,{sup 44}Ca and {sup 48}Ca isotopes have been calculated within the Extended Theory of Finite Fermi Systems (ETFFS). This approach is based on the random phase approximation (RPA) and includes the single-particle continuum as well as the coupling to low-lying collective states which are considered in a consistent microscopic way. For {sup 44}Ca we also include pairing correlations. A good agreement with the existing experimental data for the gross properties of the low-lying strength has been obtained. We conclude that for the detailed understanding of the low-lying dipole strength an approach like the present one is absolutely necessary.


    Directory of Open Access Journals (Sweden)

    Yurij K. Vasil’chuk


    Full Text Available The paper summarises stable-isotope research on massive ice in the Russian and North American Arctic, and includes the latest understanding of massive-ice formation. A new classification of massive-ice complexes is proposed, encompassing the range and variabilityof massive ice. It distinguishes two new categories of massive-ice complexes: homogeneousmassive-ice complexes have a similar structure, properties and genesis throughout, whereasheterogeneous massive-ice complexes vary spatially (in their structure and properties andgenetically within a locality and consist of two or more homogeneous massive-ice bodies.Analysis of pollen and spores in massive ice from Subarctic regions and from ice and snow cover of Arctic ice caps assists with interpretation of the origin of massive ice. Radiocarbon ages of massive ice and host sediments are considered together with isotope values of heavy oxygen and deuterium from massive ice plotted at a uniform scale in order to assist interpretation and correlation of the ice.

  14. Carbon sources in suspended particles and surface sediments from the Beaufort Sea revealed by molecular lipid biomarkers and compound-specific isotope analysis

    Directory of Open Access Journals (Sweden)

    I. Tolosa


    Full Text Available Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids and compound-specific isotope analysis of suspended particulate organic matter (SPM and surface sediments of the Mackenzie Shelf and slope (southeast Beaufort Sea, Arctic Ocean were studied in summer 2009. The concentrations of the molecular lipid markers, characteristic of known organic matter sources, were grouped and used as proxies to evaluate the relative importance of fresh algal, detrital algal, fossil, C3 terrestrial plants, bacterial and zooplankton material in the organic matter (OM of this area. Fossil and detrital algal contributions were the major fractions of the freshwater SPM from the Mackenzie River with ~34% each of the total molecular biomarkers. Fresh algal, C3 terrestrial, bacterial and zooplanktonic components represented much lower percentages, 17, 10, 4 and 80%, with a minor contribution of fossil and C3 terrestrial biomarkers. Characterization of the sediments revealed a major sink of refractory algal material mixed with some fresh algal material, fossil hydrocarbons and a small input of C3 terrestrial sources. In particular, the sediments from the shelf and at the mouth of the Amundsen Gulf presented the highest contribution of detrital algal material (60–75%, whereas those from the slope contained the highest proportion of fossil (40% and C3 terrestrial plant material (10%. Overall, considering that the detrital algal material is marine derived, autochthonous sources contributed more than allochthonous sources to the OM lipid pool. Using the ratio of an allochthonous biomarker (normalized to total organic carbon, TOC found in the sediments to those measured at the river mouth water, we estimated that the fraction of terrestrial material preserved in the sediments accounted for 30–40% of the total carbon in the inner shelf sediments, 17% in the outer shelf and Amundsen Gulf and up to 25% in the slope sediments. These estimates are low

  15. Fingerprinting TCE Sources and Natural Attenuation Capacity of a Sedimentary Bedrock Aquifer using Compound Specific Isotope Analysis - A Case Study in the City of Guelph, Ontario. (United States)

    Lima, P. L.; Aravena, R.; Parker, B. L.; Cherry, J. A.


    Chlorinated volatile organic compounds were detected in an industrial facility (site) in the upper part of the underlying dolomite bedrock aquifer. The primary chlorinated solvent detected at the site is trichloroethene (TCE), and associated daughter products, such as cis-1,2- dichloroethene (cis-1,2-DCE) and vinyl chloride (VC), are also present. Several conventional monitoring wells installed at the site were recently sampled for VOCs analysis, inorganic sensitive REDOX parameters and Compound Specific Isotope Analyses (CSIA) of 13C and 37Cl in order to evaluate the natural attenuation capacity of the local upper bedrock aquifer. A municipal well was also included in this study. The municipal well is located approximately 500 meters southwest from the investigated site and consists of anuncased bedrock well completed to 102 meters below ground surface (mbgs). Chlorinated volatile organic compounds were detected in this well during the evaluation of municipal groundwater resources performed in the early 1990s by the City of Guelph. Neither the City nor the Ministry of the Environment of the Province of Ontario (MOE) have been able to satisfactorily determine the origin of these compounds. Groundwater for VOCs analysis and CSIA were therefore collected in the municipal well in order to evaluate the relationship between the TCE detected in the municipal well and the TCE plume detected in the nearby industrial facility. The inorganic data indicated that the local upper aquifer is under sulfate-reducing conditions in some areas where typical VOC's daughter products and highly enriched δ13C and δ 37Cl values of TCE and cis-1,2-DCE were observed. These findings indicated that microbial reductive dechlorination of TCE is occurring in some areas of the local aquifer. The δ 13C values of TCE obtained in groundwater from the conventional wells were approximately 10 ‰ more depleted than δ 13C values obtained for the deep municipal production well. These data indicate

  16. Stable isotope customer list and summary of shipments - FY 1983

    Energy Technology Data Exchange (ETDEWEB)

    Davis, W.C. (comp.)


    This compilation is published as an aid to those concerned with the separation and sale of stable isotopes. The information is divided into four sections: (1) alphabetical list of domestic and foreign customers, showing the stable isotopes purchased during the fiscal year; (2) alphabetical list of isotopes, cross-referenced to customer numbers and divided into domestic and foreign categories; (3) alphabetical list of states and countries, cross-referenced to customer numbers and indicating geographical concentrations of isotope users; and (4) tabulation of the shipments, quantities, and dollars for domestic, foreign, and project categories for each isotope.

  17. Stable light isotope biogeochemistry of hydrothermal systems. (United States)

    Des Marais, D J


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

  18. Use of Compound-Specific Stable Isotope Analysis to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs (United States)


    conduct room-by-room sampling by providing real -time results that facilitate the collection of source confirmation samples. However, the required...interferents in real samples are usually more abundant and diverse than in a matrix spike. The quality of GC separation has to be assessed by a trained...BUILDING 209 3/27/2013 8:31 Hall outside EPA/ ESAT Balance and Drying Oven Lab AI U U 3/27/2013 8:46 In hall by copy machine (across from Summa

  19. Identifying migrations in marine fishes through stable-isotope analysis. (United States)

    Trueman, C N; MacKenzie, K M; Palmer, M R


    The isotopic composition of many elements varies across both land and ocean surfaces in a predictable fashion. These stable-isotope ratios are transferred into animal tissues, potentially providing a powerful natural geospatial tag. To date, most studies using stable isotopes as geolocators in marine settings have focussed on mammals and seabirds conducting large ocean-basin scale migrations. An increasing understanding of isotopic variation in the marine environment, and improved sampling and analytical techniques, however, means that stable isotopes now hold genuine promise as a natural geolocation tag in marine fishes. Here, the theoretical background underpinning the use of stable isotopes of C, N and O in otolith, scale and muscle tissues as geolocation tools in the marine environment is reviewed, and examples of their applications are provided. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

  20. Trophic position of coexisting krill species: a stable isotope approach

    DEFF Research Database (Denmark)

    Agersted, Mette Dalgaard; Bode, Antonio; Nielsen, Torkel Gissel


    Four krill species with overlapping functional biology coexist in Greenland waters. Here, we used stable isotopes to investigate and discuss their trophic role and mode of coexistence. Bulk carbon (δ13C) and nitrogen (δ15N) stable isotope analyses of Thysanoessa longicaudata, T. inermis, T. raschii...

  1. A stable isotopic study of the diet of Potamonautes sidneyi ...

    African Journals Online (AJOL)


    Jul 4, 2015 ... A stable isotope study was conducted to examine the feeding habits of the populations from Lake. Sibaya and Mpophomeni ... Keywords: diet, trophic role, stable isotopes, freshwater, brachyurans, opportunistic feeders ...... ronmental change including heavy metal and organic pollution. (Schuwerack et al.

  2. Stable isotope fractionation concepts for characterizing biotransformation of organohalides. (United States)

    Nijenhuis, Ivonne; Richnow, Hans H


    Recent development allows multi-element compound-specific isotope analysis of D, 13C, 37Cl and 81Br for characterizing the degradation pathways of halogenated organic substances in the environment. The apparent kinetic isotope effect (AKIE) obtained in (bio)degradation experiments yields information on the chemical mechanism of the bond cleavage. In biochemical reactions, rate limitation such as uptake into cells, substrate transport in cells and binding to enzymes as well as equilibrium isotope effects (EIE) are modifying the observed isotope fractionation associated with the bond cleavage reactions, thus, complicating mechanistic interpretation of isotope effect. One way for improved analysis of bond cleavage reactions by isotope effects reactions is the combination of isotope effects from two or more elements forming the reactive organic moieties where bond change reaction takes place as indicator. A further option is the combination of enantiomeric with isotope fractionation as complementary indicator for enzymatic bond cleavage reaction governing biodegradation. Finally an interesting concept with large potential for elucidation of the biochemical reaction mechanisms of biological dehalogenation may be quantum mechanical/molecular mechanical (QM/MM) modelling in combination with experimental multi-element isotope analysis, thus merging quantum chemical theory with experimental observation. Copyright © 2016. Published by Elsevier Ltd.

  3. Stable isotope deltas: Tiny, yet robust signatures in nature (United States)

    Brand, Willi A.; Coplen, Tyler B.


    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 14C 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. 13C, 2H, and 18O ) 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

  4. Stable isotope deltas: tiny, yet robust signatures in nature. (United States)

    Brand, Willi A; Coplen, Tyler B


    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

  5. Stable Isotope Database: present and past archives (United States)

    Bolliet, Timothé


    Paleoclimate data provide benchmarks against which the realism of the processes simulated by climate models can be assessed. Within this framework, it is essential to avoid introducing uncertainties associated with transfer functions and therefore to operate with robust proxies. The implementation of stable isotopes of water or carbon inside climate models motivates a synthesis of available data. Supported by the LABEX L-IPSL and involving a team of climate modelers and paleoclimatologists, this project aims to establish a worldwide database of δ18O, δD δ17O and δ13C from oceanic microfossils, corals, ice cores, cave speleothems, lakes, tree rings, and vegetation leaves wax. The aim is to provide a global vision of the hydrological cycle during the LGM and other selected key periods (last 2000 years, Mid-Holocene, Dansgaard-Oeschger events, and the Eemian). It requires screening through hundreds of published oceanic and continental records, validating the selection of the data based on resolution and chronological information. We extracted ~900 dated δ18O records from 650 marine sediment cores, 65 δ18O records from 50 ice cores, ~200 δ18O speleothems records from 60 caves, and 540 δ13C records from 290 marine sediment cores. An additional aspect of this project consists in the construction of an online portal providing an intuitive and interactive platform allowing selecting, visualizing, and downloading of the records included in this database, thus improving the distribution and comparison of paleoclimatic records from various sites.

  6. Improved Sensitivity of Spectroscopic Quantification of Stable Isotope Content Using Capillary Absorption Spectroscopy (United States)

    Moran, J.; Wilcox Freeburg, E.; Kriesel, J.; Linley, T. J.; Kelly, J.; Coleman, M. L.; Christensen, L. E.; Vance, S.


    Spectroscopy-based platforms have recently risen to the forefront for making stable isotope measurements of methane, carbon dioxide, water, or other analytes. These spectroscopy systems can be relatively straightforward to operate (versus a mass spectrometry platform), largely relieve the analyst of mass interference artifacts, and many can be used in the field. Despite these significant advantages, however, existing spectroscopy techniques suffer from a lack of measurement sensitivity that can ultimately limit select applications including spatially resolved and compound-specific measurements. Here we present a capillary absorption spectroscopy (CAS) system that is designed to mitigate sensitivity issues in spectroscopy-based stable isotope evaluation. The system uses mid-wave infrared excitation generated from a continuous wave quantum cascade laser. Importantly, the sample `chamber' is a flexible capillary with a total volume of less than one cc. Proprietary coatings on the internal surface of the fiber improve optical performance, guiding the light to a detector and facilitating high levels of interaction between the laser beam and gaseous analytes. We present data demonstrating that a tapered hollow fiber cell, with an internal diameter that broadens toward the detector, reduces optical feedback to further improve measurement sensitivity. Sensitivity of current hollow fiber / CAS systems enable measurements of only 10's of picomoles CO2 while theoretical improvements should enable measurements of as little as 10's of femtomoles. Continued optimization of sample introduction and improvements to optical feedback are being explored. Software is being designed to provide rapid integration of data and generation of processed isotope measurements using a graphical user interface. Taken together, the sensitivity improvements of the CAS system under development could, when coupled to a laser ablation sampling device, enable up to 2 µm spatial resolution (roughly the

  7. Stable isotope views on ecosystem function: challenging or challenged? (United States)

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


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

  8. Authentication of organically grown plants - advantages and limitations of atomic spectroscopy for multi-element and stable isotope analysis

    DEFF Research Database (Denmark)

    Laursen, Kristian Holst; Schjørring, Jan Kofod; Kelly, S.D.


    Organic food products are believed to be healthier, safer and more environment-friendly than their conventional counterparts and are sold at premium prices. Consequently, adulteration of organic plants and fraudulent activities for economic profit are increasing. This has spurred the development...... of sophisticated analytical procedures for testing authenticity. We review the use of multi-element and stable-isotope analysis based on atomic spectroscopy for discriminating between organic and conventional plants. We conclude that inductively-coupled plasma-mass spectrometry, stable-isotope analysis of bulk...... plant tissue, and compound-specific isotope analysis based on isotope ratio-mass spectrometry are promising tools for documenting the fertilization history of organic plants. However, these techniques are challenged by the potential diversity of fertilization practices of organic and conventional plant...

  9. SWING - The Stable Water Isotope Intercomparison Group (United States)

    Werner, M.; Barras, V.; Brown, J.; Gourcy, L.; Henderson-Sellers, A.; Hoffmann, G.; Ichiyanagi, K.; Kelley, M.; Noone, D.; Roads, J.; Schmidt, G.; Sturm, K.; Tindall, J.; Valdes, P.; Yoshimura, K.; Zakharov, V.


    For more than four decades the isotopic composition of water stored in various archives (e.g. ice cores, ground water) has been used to study changes in the hydrological cycle on timescales from glacial-interglacial to short term variations. However, the interpretation of isotopic variations in terms of climate change is often handicapped by a lack of other relevant observational climate parameters (e.g. temperature, relative humidity, precipitation) both in space and time. Modeling the isotopic composition of water within the hydrological cycle of general circulation models (GCM) may help to overcome this deficit on available climate data. Isotope GCMs simulate the 18O/16O (and/or 2H/1H) relation as an independent quantity within a closed "model world" where all other relevant climate parameters are known, too. This enables an improved analysis of (simulated) isotope variability in terms of climate change and during the last decade several state-of-the-art GCM models (GISS, ECHAM, LMD, GENESIS and others) have been enhanced by the capability to simulate the atmospheric and/or ocean cycle of H218O and 1H2H16O. To ensure isotope GCM reliability, any isotope GCM simulation must pass a rigorous comparison of simulated versus observed isotope data (model-data-intercomparison). In addition, artifacts in isotope simulations based on a specific GCM model parameterization or set-up have to be identified by comparing simulation results of several different isotope GCMs (model-model intercomparison). In our presentation we will give an overview and first results of the SWING project, founded in 2004. This initiative serves as a community platform for experts from the various isotope research groups and has the following objectives: (1) enable an overview about ongoing isotope GCM modeling capabilities; (2) define and perform future common GCM isotope simulation experiments of the various research groups; (3) identify the most important need of new observational isotope data

  10. Environmental and biomedical applications of natural metal stable isotope variations (United States)

    Bullen, T.D.; Walczyk, T.


    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.

  11. Application of enriched stable isotopes as tracers in biological systems

    DEFF Research Database (Denmark)

    Stürup, Stefan; Hansen, Helle Rüsz; Gammelgaard, Bente


    The application of enriched stable isotopes of minerals and trace elements as tracers in biological systems is a rapidly growing research field that benefits from the many new developments in inorganic mass spectrometric instrumentation, primarily within inductively coupled plasma mass spectrometry......, and the development of new methodologies coupled with more advanced compartmental and mathematical models for the distribution of elements in living organisms has enabled a broader use of enriched stable isotope experiments in the biological sciences. This review discusses the current and future uses of enriched...... stable isotope experiments in biological systems....

  12. An estimation of Central Iberian Peninsula atmospheric δ13C and water δD in the Upper Cretaceous using pyrolysis compound specific isotopic analysis (Py-CSIA) of a fossil conifer. (United States)

    González-Pérez, José A.; Jiménez-Morillo, Nicasio T.; De la Rosa, José M.; Almendros, Gonzalo; González-Vila, Francisco J.


    Frenelopsis is a frequently found genus of the Cretaceous floras adapted to dry, saline and in general to environmental conditions marked by severe water stress [1]. Stable isotope analysis of fossil organic materials can be used to infer palaeoenvironmental variables helpful to reconstruct plant paleohabitats [2]. In this study stable isotope analysis of organic fossil remains (FR) and humic fractions (FA, HA and humin) of Frenelopsis oligiostomata are studied in bulk (C, H, O, N IRMS) and in specific compounds released by pyrolysis (C, H, Py-CSIA). Well preserved F. oligiostomata fossils were handpicked from a limestone included in compacted marls from Upper Cretaceous (Senonian c. 72 Mya) in Guadalix de la Sierra (Madrid, Spain) [3]. The fossils were decarbonated with 6M HCl. Humic substances were extracted from finely ground fossil remains (FR) by successive treatments with 0.1M Na4P2O7 + NaOH [4]. The extract was acidified resulting into insoluble HA and soluble FA fractions. The HA and FA were purified as in [5] and [6] respectively. Bulk stable isotopic analysis (δ13C, δD, δ18O, δ15N IRMS) was done in an elemental micro-analyser coupled to a continuous flow Delta V Advantage isotope ratio mass spectrometer (IRMS). Pyrolysis compound specific isotopic analysis Py-CSIA (δ13C, δD): was done by coupling a double-shot pyrolyzer to a chromatograph connected to an IRMS. Structural features of specific peaks were inferred by comparing/matching mass spectra from conventional Py-GC/MS (data not shown) with Py-GC/IRMS chromatograms obtained using the same chromatographic conditions. Bulk C isotopic signature found for FR (-20.5±0.02 ‰) was in accordance with previous studies [2, 7-9]. This heavy isotopic δ13C signature indicates a depleted stomatal conductance and paleoenvironmental growth conditions of water and salt stress. This is in line with the morphological and depositional characteristics [3] confirming that F. oligostomata was adapted to highly xeric

  13. Stable carbon isotope ratios from archaeological charcoal as palaeoenvironmental indicators

    CSIR Research Space (South Africa)

    Hall, G


    Full Text Available The potential to provide environmental proxies using stable carbon isotopes from modern and archaeological charcoal is explored. Experiments on modern Podocarpus (Yellowwoods) show that δ13C values of stems, branches and charcoal preserve proxy...

  14. Arctic cisco stable isotope data, Prudhoe Bay, August 2009 (United States)

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

  15. Stable isotope labeling strategy based on coding theory

    Energy Technology Data Exchange (ETDEWEB)

    Kasai, Takuma; Koshiba, Seizo; Yokoyama, Jun; Kigawa, Takanori, E-mail: [RIKEN Quantitative Biology Center (QBiC), Laboratory for Biomolecular Structure and Dynamics (Japan)


    We describe a strategy for stable isotope-aided protein nuclear magnetic resonance (NMR) analysis, called stable isotope encoding. The basic idea of this strategy is that amino-acid selective labeling can be considered as “encoding and decoding” processes, in which the information of amino acid type is encoded by the stable isotope labeling ratio of the corresponding residue and it is decoded by analyzing NMR spectra. According to the idea, the strategy can diminish the required number of labelled samples by increasing information content per sample, enabling discrimination of 19 kinds of non-proline amino acids with only three labeled samples. The idea also enables this strategy to combine with information technologies, such as error detection by check digit, to improve the robustness of analyses with low quality data. Stable isotope encoding will facilitate NMR analyses of proteins under non-ideal conditions, such as those in large complex systems, with low-solubility, and in living cells.

  16. Stable isotopes: essential tools in biological and medical research

    Energy Technology Data Exchange (ETDEWEB)

    Klein, P. D.; Hachey, D. L.; Kreek, M. J.; Schoeller, D. A.


    Recent developments in the use of the stable isotopes, /sup 13/C, /sup 15/N, /sup 17/O, and /sup 18/O, as tracers in research studies in the fields of biology, medicine, pharmacology, and agriculture are briefly reviewed. (CH)

  17. US ITASE Stable Isotope Data, Antarctica, Version 1 (United States)

    National Aeronautics and Space Administration — This data set includes stable isotope measurements from snow pits, firn, and ice cores collected by the the US component of the International Trans-Antarctic...

  18. Variation in carbon and nitrogen stable isotope ratios in flight ...

    African Journals Online (AJOL)

    bellied Sunbird to assess the value of using stable isotopes of feathers in avian dietary studies. Significant variation in δ13C and δ15N isotope values of flight feathers (range = 3.1‰ and 2.7‰, respectively) indicated that the source of carbon (i.e. ...

  19. Stable isotope customer list and summary of shipments, FY 1977

    Energy Technology Data Exchange (ETDEWEB)

    Davis, W.C.


    The compilation of stable isotope customers and shipments is divided into four parts. There are alphabetical lists of domestic and foreign customers, alphabetical list of isotopes with cross-references to customers, alphabetical list of states and customers with cross-reference to customers, and tabulation of shipments, quantities, and dollars. (JSR)


    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...

  1. Stable carbon isotope fractionation during the biodegradation of lambda-cyhalothrin. (United States)

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


    In this study, the microbial degradation of lambda-cyhalothrin in soil was investigated using compound-specific stable isotope analysis. The results revealed that lambda-cyhalothrin was biodegraded in soil under laboratory conditions. The half-lives of lambda-cyhalothrin were determined to be 49 and 161 days in non-sterile and sterile soils spiked with 2mg/kg lambda-cyhalothrin and 84 and 154 days in non-sterile and sterile soils spiked with 10mg/kg lambda-cyhalothrin, respectively. The biodegradation of lambda-cyhalothrin resulted in carbon isotope fractionation, which shifted from -29.0‰ to -26.5‰ in soil spiked with 2mg/kg lambda-cyhalothrin, and to -27.5‰ with 10mg/kg lambda-cyhalothrin. A relationship was established between the stable carbon isotope fraction and the residual concentrations of lambda-cyhalothrin by the Rayleigh equation in which the carbon isotope enrichment factor ε of the microbial degradation of lambda-cyhalothrin in the soil was calculated as -2.53‰. This study provides an approach to quantitatively evaluate the biodegradation of lambda-cyhalothrin in soil in field studies. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Benchmarking stable isotope labeling based quantitative proteomics

    NARCIS (Netherlands)

    Altelaar, A.F.M.|info:eu-repo/dai/nl/304833517; Frese, C.K.; Preisinger, C.|info:eu-repo/dai/nl/325801703; Hennrich, M.L.|info:eu-repo/dai/nl/314406778; Schram, A.W.; Timmers, H.T.M.; Heck, A.J.R.|info:eu-repo/dai/nl/105189332; Mohammed, S.|info:eu-repo/dai/nl/30483632X

    Several quantitative mass spectrometry based technologies have recently evolved to interrogate the complexity, interconnectivity and dynamic nature of proteomes. Currently, the most popular methods use either metabolic or chemical isotope labeling with MS based quantification or chemical labeling

  3. Stable Isotope Dilution Mass Spectrometry for Membrane Transporter Quantitation


    Farrokhi, Vahid; McShane, Adam J.; Nemati, Reza; Yao, Xudong


    This review provides an introduction to stable isotope dilution mass spectrometry (MS) and its emerging applications in the analysis of membrane transporter proteins. Various approaches and application examples, for the generation and use of quantitation reference standards—either stable isotope-labeled peptides or proteins—are discussed as they apply to the MS quantitation of membrane proteins. Technological considerations for the sample preparation of membrane transporter proteins are also ...

  4. Assessing anthropogenic pressures on groundwater using stable OH isotopes: perspectives and issues (United States)

    Negrel, Philippe; Ollivier, Patrick; Flehoc, Christine; Hube, Daniel


    Large developments of isotope hydrogeology were done and well-established techniques mainly applying stable isotopes of the water molecule (hydrogen and oxygen) are now used largely to trace water provenance but also recharge processes. New methods allow the use of non-traditional isotopes (metals, compound specific stable isotope analysis CSIA...) to trace anthropogenic pressures in surface- and groundwater. Groundwater contamination in large industrial sites may come from several origins such as leakage from tanks during the production process of chemical products, liquid storage tanks, solid end product or past accumulated product in soil which is released over the time. The understanding of the origin and the further evolution of the chemical contamination in groundwater in an industrial site issued from past or current industrial activities is essential for the industrial companies regarding their environmental policies. The objective of this study was to use with an innovative way the stable isotopes of the water molecule as a low cost tool to trace pollutant plumes in groundwater and help to a better management of contaminated industrial sites. We present data on stable isotopes O and H in an European region where electrochemistry plants occur. For confidentiality purposes, the sites remain anonymous. Present day industrial activities have a direct impact on the groundwater over the site and migration of the contaminant(s) plume out of the site is supposed. We first characterize the natural groundwater background through the O-H characterization of surface water, lakes, thermal waters and regional shallow aquifers. High and low altitude recharge can be demonstrated in the area. Secondly, we used the stable isotope of the water molecule to trace over the site the impact of the Cl-rich liquor manufacturing process. Large deuterium enrichment was evidenced in the groundwater and the high values can be related to a direct contamination of the groundwater through

  5. Stable Chlorine Isotope Study: Application to Early Solar System Materials (United States)

    Mala,ira. M/; Nyquist, L. E.; Reese, Y.; Shih, C-Y; Fujitani, T.; Okano, O.


    A significantly large mass fractionation between two stable chlorine isotopes is expected during planetary processes In addition, in view of the isotopic heterogeneity of other light elements, the chlorine isotopes can potentially be used as a tracer for the origins and evolutionary processes of early solar system materials. Due to analytical difficulties, however, current chlorine isotope studies on planetary materials are quite controversial among IRMS (gas source mass spectrometry) and/or TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1-3]. Although a cross-calibration of IRMS and TIMS indicates that both techniques are sufficiently consistent with each other [4], some authors have claimed that the Cl-37/Cl-35 ratio of geological samples obtained by TIMS technique are, in general, misleadingly too high and variable compared to those of IRMS [3]. For example, almost no differences of Cl isotope composition were observed among mantle materials and carbonaceous meteorites by [3]. On the other hand, according to more recent IRMS work [2], significant Cl isotope variations are confirmed for mantle materials. Therefore, additional careful investigation of Cl isotope analyses are now required to confirm real chlorine isotope variations for planetary materials including carbonaceous chondrites [5]. A significantly large mass fractionation between two stable chlorine isotopes is expected during planetary processes In addition, in view of the isotopic heterogeneity of other light elements, the chlorine isotopes can potentially be used as a tracer for the origins and evolutionary processes of early solar system materials. Due to analytical difficulties, however, current chlorine isotope studies on planetary materials are quite controversial among IRMS (gas source mass spectrometry) and/or TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1-3]. Although a cross-calibration of IRMS and TIMS indicates that both techniques are sufficiently consistent with each

  6. Stable Oxygen-18 and Deuterium Isotopes

    DEFF Research Database (Denmark)

    Müller, Sascha

    link the observed seasonal regression/transgression pattern to the inland recharge cycle, which is expressed in hydraulic head configuration and submarine groundwater discharge rates at the fieldsite. Nonetheless, those observed dynamics could not be simulated due to numerical limitations. By the use...... the Skjern River catchment, Denmark. The presented applications focused on studying the isotopic 'input signal' to the hydrosphere in the form of precipitation, the isotopic 'output signal' with its related dynamic processes at a coastal saltwater-freshwater interface (groundwater isotopes) and the temporal...... young age. Those results are in contrast to earlier age estimations from groundwater samples just beneath the stream. We therefore suggest the conceptualization of the hydrological conditions at this headwater catchment to be revised....

  7. Development of O-18 stable isotope separation technology using membrane

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Woo; Kim, Taek Soo; Choi, Hwa Rim; Park, Sung Hee; Lee, Ki Tae; Chang, Dae Shik


    The ultimate goal of this investigation is to develop the separation technology for O-18 oxygen stable isotope used in a cyclotron as a target for production of radioisotope F-18. F-18 is a base material for synthesis of [F-18]FDG radio-pharmaceutical, which is one of the most important tumor diagnostic agent used in PET (Positron Emission Tomography). More specifically, this investigation is focused on three categories as follow, 1) development of the membrane distillation isotope separation process to re-enrich O-18 stable isotope whose isotopic concentration is reduced after used in a cyclotron, 2) development of organic impurity purification technology to remove acetone, methanol, ethanol, and acetonitrile contained in a used cyclotron O-18 enriched target water, and 3) development of a laser absorption spectroscopic system for analyzing oxygen isotopic concentration in water.

  8. Fractionation of metal stable isotopes by higher plants (United States)

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


    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.

  9. Stable Isotope Ratios as Biomarkers of Diet for Health Research. (United States)

    O'Brien, Diane M


    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.

  10. Quinone-based stable isotope probing for assessment of 13C substrate-utilizing bacteria (United States)

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


    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

  11. Stable Carbon Isotope Ratios of Specific Products in Secondary Particulate Organic Matter Formed by Photo-Oxidation of Toluene (United States)

    Irei, S.; Rudolph, J.; Huang, L.; Auld, J.; Hastie, D.


    Laboratory experiments for stable carbon isotope studies of secondary particulate organic matter (POM) in the gas-phase were conducted. Secondary POM was generated using a 2.5 L flow reactor or an 8 m3 smog chamber. The initial mixing ratio of toluene and the initial toluene/NO ratio were 20 ppmV - 40 ppmV and 4 - 8 for the flow reactor experiments and ~0.5 ppmV and 0.3 - 2 for the smog chamber experiments, respectively. The flow reactor experiments were made without seed particles, while the smog chamber experiments were done with ammonium sulfate seed particles. Using these different experimental set-ups/conditions, POM generated under different extent of toluene consumption was collected on filters for compound-specific stable carbon isotope analysis as well as for the stable carbon isotope analysis of total POM carbon. For the compound specific analysis, the collected filter samples were extracted with acetonitrile, and the extracts were then concentrated under a gentle flow of pure nitrogen gas. The concentrated extracts were derivatized using N, O-bis(trimethylsilyl)trifluoroacetoamide (BSTFA). The derivatives were qualitatively and quantitatively/isotopically analyzed by GC-MS and GC-C-IRMS, respectively. The qualitative analysis by the GC-MS identified 7 nitromonohydroxy/nitrodihydroxy aromatic compounds in the POM extracts. The results from the compound-specific stable carbon analysis show that, for 6 out of the 7 identified products, the isotope ratios were the similar to that of the total POM carbon, which is predictable using the kinetic isotope effect of the initial toluene+OH reaction, the initial isotope ratio of toluene, and fraction of toluene consumed (Irei et al., 2006). In this presentation, comparison of these observations with the reaction mechanisms postulated by others will be discussed. Reference Flow reactor studies for stable carbon isotopic composition of secondary particulate organic matter generated by toluene/OH radical

  12. Stable carbon isotope analysis of coprocessing materials

    Energy Technology Data Exchange (ETDEWEB)

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


    The program is designed to address a substantial, demonstrated need of the coprocessing community (both exploratory and development) for a technique to quantitatively distinguish the contributions of the individual coprocessing feedstocks to the various products. The carbon isotope technique is currently in routine use for other applications. Results achieved this quarter include: Feed and product fractions from a Kentucky 9 coal/Kentucky tar sand bitumen coprocessing bench unit run at the Kentucky Center for Applied Energy Research (CAER) were analyzed for carbon isotope ratios. Corrections were made to the coal carbon recoveries and selectivities from the products of HRI Run 227-53. Feeds (Westerholt coal/Cold Lake VSB) and products from two periods of HRI coprocessing Run 238-1 were analyzed. Three petroleum samples and three coal samples were pyrolyzed at 800{degree}F for 30 min to determine the effect of pyrolysis on the isotopic homogeneity of each petroleum and coal sample. Products from each pyrolysis test were separated into five fractions; an additional set of coprocessing samples and a set of two-stage coal liquefaction samples were obtained from HRI for future work; work performed by the Pennsylvania State University show that microscopy is a promising method for distinguishing coal and petroleum products in residual coprocessing materials; and coal and petroleums that have large differences in carbon isotope ratios were identified for Auburn University. 7 refs., 2 figs., 12 tabs.

  13. Principles and limitations of stable isotopes in differentiating organic and conventional foodstuffs: 2. Animal products. (United States)

    Inácio, Caio T; Chalk, Phillip M


    In this review, we examine the variation in stable isotope signatures of the lighter elements (δ 2 H, δ 13 C, δ 15 N, δ 18 O, and δ 34 S) of tissues and excreta of domesticated animals, the factors affecting the isotopic composition of animal tissues, and whether stable isotopes may be used to differentiate organic and conventional modes of animal husbandry. The main factors affecting the δ 13 C signatures of livestock are the C3/C4 composition of the diet, the relative digestibility of the diet components, metabolic turnover, tissue and compound specificity, growth rate, and animal age. δ 15 N signatures of sheep and cattle products have been related mainly to diet signatures, which are quite variable among farms and between years. Although few data exist, a minor influence in δ 15 N signatures of animal products was attributed to N losses at the farm level, whereas stocking rate showed divergent findings. Correlations between mode of production and δ 2 H and δ 18 O have not been established, and only in one case of an animal product was δ 34 S a satisfactory marker for mode of production. While many data exist on diet-tissue isotopic discrimination values among domesticated animals, there is a paucity of data that allow a direct and statistically verifiable comparison of the differences in the isotopic signatures of organically and conventionally grown animal products. The few comparisons are confined to beef, milk, and egg yolk, with no data for swine or lamb products. δ 13 C appears to be the most promising isotopic marker to differentiate organic and conventional production systems when maize (C4) is present in the conventional animal diet. However, δ 13 C may be unsuitable under tropical conditions, where C4 grasses are abundant, and where grass-based husbandry is predominant in both conventional and organic systems. Presently, there is no universal analytical method that can be applied to differentiate organic and conventional animal products.

  14. Stable isotope composition of human fingernails from Slovakia

    Energy Technology Data Exchange (ETDEWEB)

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


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

  15. New Organic Stable Isotope Reference Materials for Distribution through the USGS and the IAEA (United States)

    Schimmelmann, Arndt; Qi, Haiping


    The widespread adoption of relative stable isotope-ratio measurements in organic matter by diverse scientific disciplines is at odds with the dearth of international organic stable isotopic reference materials (RMs). Only two of the few carbon (C) and nitrogen (N) organic RMs, namely L-glutamic acids USGS40 and USGS41 [1], both available from the U.S. Geological Survey (USGS) and the International Atomic Energy Agency (IAEA), provide an isotopically contrasting pair of organic RMs to enable essential 2-point calibrations for δ-scale normalization [2, 3]. The supply of hydrogen (H) organic RMs is even more limited. Numerous stable isotope laboratories have resorted to questionable practices, for example by using 'CO2, N2, and H2 reference gas pulses' for isotopic calibrations, which violates the principle of identical treatment of sample and standard (i.e., organic unknowns should be calibrated directly against chemically similar organic RMs) [4], or by using only 1 anchor instead of 2 for scale calibration. The absence of international organic RMs frequently serves as an excuse for indefensible calibrations. In 2011, the U.S. National Science Foundation (NSF) funded an initiative of 10 laboratories from 7 countries to jointly develop much needed new organic RMs for future distribution by the USGS and the IAEA. The selection of targeted RMs attempts to cover various common compound classes of broad technical and scientific interest. We had to accept compromises to approach the ideal of high chemical stability, lack of toxicity, and low price of raw materials. Hazardous gases and flammable liquids were avoided in order to facilitate international shipping of future RMs. With the exception of polyethylene and vacuum pump oil, all organic RMs are individual, chemically-pure substances, which can be used for compound-specific isotopic measurements in conjunction with liquid and gas chromatographic interfaces. The compounds listed below are under isotopic calibration by

  16. Use of Stable Isotopes in Forensic Analysis of Microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Kreuzer-Martin, Helen W.; Hegg, Eric L.


    The use of isotopic signatures for forensic analysis of biological materials is well-established, and the same general principles that apply to interpretation of stable isotope content of C, N, O, and H apply to the analysis of microorganisms. Heterotrophic microorganisms derive their isotopic content from their growth substrates, which are largely plant and animal products, and the water in their culture medium. Thus the isotope signatures of microbes are tied to their growth environment. The C, N, O, and H isotope ratios of spores have been demonstrated to constitute highly discriminating signatures for sample matching. They can rule out specific samples of media and/or water as possible production media, and can predict isotope ratio ranges of the culture media and water used to produce a given sample. These applications have been developed and tested through analyses of approximately 250 samples of Bacillus subtilis spores and over 500 samples of culture media, providing a strong statistical basis for data interpretation. A Bayesian statistical framework for integrating stable isotope data with other types of signatures derived from microorganisms has been able to characterize the culture medium used to produce spores of various Bacillus species, leveraging isotopic differences in different medium types and demonstrating the power of data integration for forensic investigations.

  17. Stable platinum isotope measurements in presolar nanodiamonds by TEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Wallner, A., E-mail: [University of Vienna, Faculty of Physics, VERA Laboratory, Waehringer Strasse 17, A-1090 Vienna (Austria); Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra (Australia); Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights (Australia); Melber, K. [University of Vienna, Faculty of Physics, VERA Laboratory, Waehringer Strasse 17, A-1090 Vienna (Austria); Merchel, S. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01314 Dresden (Germany); Ott, U. [Max-Planck-Institut fuer Chemie, Joh.-J.-Becherweg 27, D-55128 Mainz (Germany); Forstner, O.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P. [University of Vienna, Faculty of Physics, VERA Laboratory, Waehringer Strasse 17, A-1090 Vienna (Austria)


    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 {sup 198}Pt/{sup 195}Pt 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.

  18. Stable isotope geochemistry of East African waters. [Abstract only

    Energy Technology Data Exchange (ETDEWEB)

    Sayer, M.D.; Cerling, T.E.; Bowman, J.R.


    Lakes and Rivers in East Africa have varied stable isotopic compositions. Lakes exhibit enriched delta13-C values (-2 to +5%), while their inflowing rivers show depleted values (-15 to -8%). Hot springs and standing pools of water have intermediate values. Some small lakes are extremely variable in delta18-0 or deltaD (+2 to +8% and +20 to +40%, respectively for Lake Naivasha), whereas larger lakes are relatively constant for long periods of time (+5.6 to 6.1 and +36 to 40, respectively for Lake Turkana). Isotopic values are unrelated to salinity for comparison between lakes. Stable isotopes also reveal the sources of hot spring discharges: the Kapedo hot springs probably originate from Maralel and not from Lake Baringo as local legend has it; the hot springs north of Lake Naivasha are of meteoric origin while those to the south of Lake Naivasha have similar isotopic compositions to Lake Naivasha.

  19. Stable isotope tracers: natural and anthropogenic recharge, Orange County, California (United States)

    Williams, Alan E.


    Stable isotopic techniques have been utilized to locate occurrences and trace movements of a variety of naturally and anthropogenically recharged waters in aquifers of Orange County, California. This basin is of particular interest not only because it provides the dominant water supply for the two million residents of this well-populated county, but also because it is representative of a common arid environment where natural recharge is dominated by distant, high-elevation precipitation transported by a major river. Such arid basins are particularly sensitive to climatic and anthropogenic disturbance of their recharge and their subsurface hydrology. In order to identify distinctive waters, oxygen and hydrogen stable isotope ratios from Orange County wells have been compared with a regional database including an array of surface water samples representative of watershed runoff. Four distinctive subsurface water types can be resolved. Waters of "local" rainfall and imported, "Colorado" River aqueduct origins are easily distinguished from dominant, "native" Santa Ana river compositions by use of hydrogen and oxygen stable isotope analysis. Recent human interference with Santa Ana river flow and recharge is also marginally resolvable by isotopic techniques. Distinguishable isotopic signatures of "recent" Santa Ana recharge appear to be due to evaporative loss, perhaps during storage in the Prado Reservoir or in percolation ponds, prior to recharge into Orange County aquifers. Characterization of traceable isotopic signatures of distinct natural and anthropogenic recharge components provides a major advance towards use of such techniques for developing a well constrained, three-dimensional hydrologic model for this complex basin.

  20. Referencing strategies and techniques in stable isotope ratio analysis. (United States)

    Werner, R A; Brand, W A


    Stable isotope ratios are reported in the literature in terms of a deviation from an international standard (delta-values). The referencing procedures, however, differ from instrument to instrument and are not consistent between measurement facilities. This paper reviews an attempt to unify the strategy for referencing isotopic measurements. In particular, emphasis is given to the importance of identical treatment of sample and reference material ('IT principle'), which should guide all isotope ratio determinations and evaluations. The implementation of the principle in our laboratory, the monitoring of our measurement quality, the status of the international scales and reference materials and necessary correction procedures are discussed. Copyright 2001 John Wiley & Sons, Ltd.

  1. Copper stable isotopes to trace copper behavior in wetland systems. (United States)

    Babcsányi, Izabella; Imfeld, Gwenaël; Granet, Mathieu; Chabaux, François


    Wetlands are reactive zones of the landscape that can sequester metals released by industrial and agricultural activities. Copper (Cu) stable isotope ratios (δ(65)Cu) have recently been used as tracers of transport and transformation processes in polluted environments. Here, we used Cu stable isotopes to trace the behavior of Cu in a stormwater wetland receiving runoff from a vineyard catchment (Alsace, France). The Cu loads and stable isotope ratios were determined in the dissolved phase, suspended particulate matter (SPM), wetland sediments, and vegetation. The wetland retained >68% of the dissolved Cu and >92% of the SPM-bound Cu, which represented 84.4% of the total Cu in the runoff. The dissolved Cu became depleted in (65)Cu when passing through the wetland (Δ(65)Cuinlet-outlet from 0.03‰ to 0.77‰), which reflects Cu adsorption to aluminum minerals and organic matter. The δ(65)Cu values varied little in the wetland sediments (0.04 ± 0.10‰), which stored >96% of the total Cu mass within the wetland. During high-flow conditions, the Cu flowing out of the wetland became isotopically lighter, indicating the mobilization of reduced Cu(I) species from the sediments and Cu reduction within the sediments. Our results demonstrate that the Cu stable isotope ratios may help trace Cu behavior in redox-dynamic environments such as wetlands.

  2. Spatial distribution of stable water isotopes in alpine snow cover

    Directory of Open Access Journals (Sweden)

    N. Dietermann


    Full Text Available The aim of this study was to analyse and predict the mean stable water isotopic composition of the snow cover at specific geographic locations and altitudes. In addition, the dependence of the isotopic composition of the entire snow cover on altitude was analysed. Snow in four Swiss catchments was sampled at the end of the accumulation period in April 2010 and a second time during snowmelt in May 2010 and analysed for stable isotope composition of 2H and 18O. The sampling was conducted at both south-facing and north-facing slopes at elevation differences of 100 m, for a total altitude difference of approximately 1000 m. The observed variability of isotopic composition of the snow cover was analysed with stepwise multiple linear regression models. The analysis indicated that there is only a limited altitude effect on the isotopic composition when considering all samples. This is due to the high variability of the isotopic composition of the precipitation during the winter months and, in particular in the case of south-facing slopes, an enrichment of heavy isotopes due to intermittent melting processes. This enrichment effect could clearly be observed in the samples which were taken later in the year. A small altitudinal gradient of the isotopic composition could only be observed at some north-facing slopes. However, the dependence of snow depth and the day of the year were significant predictor variables in all models. This study indicates the necessity to further study the variability of water isotopes in the snow cover to increase prediction for isotopic composition of snowmelt and hence increase model performance of residence time models for alpine areas in order to better understand the accumulation processes and the sources of water in the snow cover of high mountains.

  3. Spatial distribution of stable water isotopes in alpine snow cover (United States)

    Dietermann, N.; Weiler, M.


    The aim of this study was to analyse and predict the mean stable water isotopic composition of the snow cover at specific geographic locations and altitudes. In addition, the dependence of the isotopic composition of the entire snow cover on altitude was analysed. Snow in four Swiss catchments was sampled at the end of the accumulation period in April 2010 and a second time during snowmelt in May 2010 and analysed for stable isotope composition of 2H and 18O. The sampling was conducted at both south-facing and north-facing slopes at elevation differences of 100 m, for a total altitude difference of approximately 1000 m. The observed variability of isotopic composition of the snow cover was analysed with stepwise multiple linear regression models. The analysis indicated that there is only a limited altitude effect on the isotopic composition when considering all samples. This is due to the high variability of the isotopic composition of the precipitation during the winter months and, in particular in the case of south-facing slopes, an enrichment of heavy isotopes due to intermittent melting processes. This enrichment effect could clearly be observed in the samples which were taken later in the year. A small altitudinal gradient of the isotopic composition could only be observed at some north-facing slopes. However, the dependence of snow depth and the day of the year were significant predictor variables in all models. This study indicates the necessity to further study the variability of water isotopes in the snow cover to increase prediction for isotopic composition of snowmelt and hence increase model performance of residence time models for alpine areas in order to better understand the accumulation processes and the sources of water in the snow cover of high mountains.

  4. [Progress in stable isotope labeled quantitative proteomics methods]. (United States)

    Zhou, Yuan; Shan, Yichu; Zhang, Lihua; Zhang, Yukui


    Quantitative proteomics is an important research field in post-genomics era. There are two strategies for proteome quantification: label-free methods and stable isotope labeling methods which have become the most important strategy for quantitative proteomics at present. In the past few years, a number of quantitative methods have been developed, which support the fast development in biology research. In this work, we discuss the progress in the stable isotope labeling methods for quantitative proteomics including relative and absolute quantitative proteomics, and then give our opinions on the outlook of proteome quantification methods.

  5. Enantioselective carbon stable isotope fractionation of hexachlorocyclohexane during aerobic biodegradation by Sphingobium spp. (United States)

    Bashir, Safdar; Fischer, Anko; Nijenhuis, Ivonne; Richnow, Hans-Hermann


    Carbon isotope fractionation was investigated for the biotransformation of γ- and α- hexachlorocyclohexane (HCH) as well as enantiomers of α-HCH using two aerobic bacterial strains: Sphingobium indicum strain B90A and Sphingobium japonicum strain UT26. Carbon isotope enrichment factors (ε(c)) for γ-HCH (ε(c) = -1.5 ± 0.1 ‰ and -1.7 ± 0.2 ‰) and α-HCH (ε(c) = -1.0 ± 0.2 ‰ and -1.6 ± 0.3 ‰) were similar for both aerobic strains, but lower in comparison with previously reported values for anaerobic γ- and α-HCH degradation. Isotope fractionation of α-HCH enantiomers was higher for (+) α-HCH (ε(c) = -2.4 ± 0.8 ‰ and -3.3 ± 0.8 ‰) in comparison to (-) α-HCH (ε(c) = -0.7 ± 0.2 ‰ and -1.0 ± 0.6 ‰). The microbial fractionation between the α-HCH enantiomers was quantified by the Rayleigh equation and enantiomeric fractionation factors (ε(e)) for S. indicum strain B90A and S. japonicum strain UT26 were -42 ± 16% and -22 ± 6%, respectively. The extent and range of isomer and enantiomeric carbon isotope fractionation of HCHs with Sphingobium spp. suggests that aerobic biodegradation of HCHs can be monitored in situ by compound-specific stable isotope analysis (CSIA) and enantiomer-specific isotope analysis (ESIA). In addition, enantiomeric fractionation has the potential as a complementary approach to CSIA and ESIA for assessing the biodegradation of α-HCH at contaminated field sites.

  6. Discrimination of ginseng cultivation regions using light stable isotope analysis. (United States)

    Kim, Kiwook; Song, Joo-Hyun; Heo, Sang-Cheol; Lee, Jin-Hee; Jung, In-Woo; Min, Ji-Sook


    Korean ginseng is considered to be a precious health food in Asia. Today, thieves frequently compromise ginseng farms by pervasive theft. Thus, studies regarding the characteristics of ginseng according to growth region are required in order to deter ginseng thieves and prevent theft. In this study, 6 regions were selected on the basis of Korea regional criteria (si, gun, gu), and two ginseng-farms were randomly selected from each of the 6 regions. Then 4-6 samples of ginseng were acquired from each ginseng farm. The stable isotopic compositions of H, O, C, and N of the collected ginseng samples were analyzed. As a result, differences in the hydrogen isotope ratios could be used to distinguish regional differences, and differences in the nitrogen isotope ratios yielded characteristic information regarding the farms from which the samples were obtained. Thus, stable isotope values could be used to differentiate samples according to regional differences. Therefore, stable isotope analysis serves as a powerful tool to discriminate the regional origin of Korean ginseng samples from across Korea. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. Century-long source apportionment of PAHs in Athabasca oil sands region lakes using diagnostic ratios and compound-specific carbon isotope signatures. (United States)

    Jautzy, Josué; Ahad, Jason M E; Gobeil, Charles; Savard, Martine M


    Evaluating the impact that airborne contamination associated with Athabasca oil sands (AOS) mining operations has on the surrounding boreal forest ecosystem requires a rigorous approach to source discrimination. This study presents a century-long historical record of source apportionment of polycyclic aromatic hydrocarbons (PAHs) in dated sediments from two headwater lakes located approximately 40 and 55 km east from the main area of open pit mining activities. Concentrations of the 16 Environmental Protection Agency (EPA) priority PAHs in addition to retene, dibenzothiophene (DBT), and six alkylated groups were measured, and both PAH molecular diagnostic ratios and carbon isotopic signatures (δ(13)C) of individual PAHs were used to differentiate natural from anthropogenic inputs. Although concentrations of PAHs in these lakes were low and below the Canadian Council of Ministers of the Environment (CCME) guidelines, diagnostic ratios pointed to an increasingly larger input of petroleum-derived (i.e., petrogenic) PAHs over the past 30 years concomitant with δ(13)C values progressively shifting to the value of unprocessed AOS bitumen. This petrogenic source is attributed to the deposition of bitumen in dust particles associated with wind erosion from open pit mines.

  8. Modeled and measured stable isotope data in Siberian tree rings (United States)

    Sidorova, Olga; Siegwolf, Rolf; Kupzova, Anna; Launois, Thomas; Peylin, Philippe; Spahni, Renato; Bryukhanova, Marina; Roden, John; Saurer, Matthias; Shashkin, Aleksander


    Stable isotopes in tree-rings are widely used for the reconstruction of environmental conditions, but more information could be extracted when using mechanistic models for their interpretation. Tree-ring width, cell wall structure and stable carbon as well as oxygen isotope analyses in tree wood and cellulose were carried out for four larch trees (Larix cajanderi Mayr) from northeastern Yakutia (69°N, 148°E) during the period from 1945 to 2004 and these data compared with several models. Based on a biochemical model of photosynthesis and modified model of stomatal conductance our work provides intra-annual dynamics of carbon content in photoassimilates and isotope composition in tree-rings depending on climatic factors. The mechanistic Roden-Lin-Ehleringer model was used to quantify both the physical and biochemical fractionation events associated with hydrogen and oxygen isotope ratios in tree-ring cellulose. Simulation results were compared with measured data. Predictions of carbon isotope ratios from Fritts, ORCHIDEE and LPX models were consistent with measured data. The Roden-Lin-Ehleringer oxygen model allowed the prediction of humidity and source water enrichment as well as oxygen isotope effects associated with leaf water enrichment. This work was supported by Marie Curie Fellowships (EU-ISOTREC 235122; 909122) awarded to Sidorova Olga and a grant of Russian Scientific School 5327.2012.4.

  9. Stable isotopes of captive cetaceans (killer whales and bottlenose dolphins). (United States)

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


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

  10. Incorporating stable isotopes into a multidisciplinary framework to ...

    African Journals Online (AJOL)

    Through its ability to address complex ecological questions and the possibility of analysing large sample sizes to understand population-level processes, the use of stable isotope analysis (δ13C and δ15N) has grown rapidly in recent years. Importantly, it is now becoming an accepted tool to derive data for conservation and ...

  11. Divergence of stable isotopes in tap water across China

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Sihan; Hu, Hongchang; Tian, Fuqiang; Tie, Qiang; Wang, Lixin; Liu, Yaling; Shi, Chunxiang


    Stable isotopes in water (e.g., δ2H and δ18O) are important indicators of hydrological and ecological patterns and processes. Tap water can reflect integrated features of regional hydrological processes and human activities. China is a large country with significant meteorological and geographical variations. This report presents the first national-scale survey of Stable Isotopes in Tap Water (SITW) across China. 780 tap water samples have been collected from 95 cities across China from December 2014 to December 2015. (1) Results yielded the Tap Water Line in China is δ2H = 7.72 δ18O + 6.57 (r2 = 0.95). (2) SITW spatial distribution presents typical "continental effect". (3) SITW seasonal variations indicate clearly regional patterns but no trends at the national level. (4) SITW can be correlated in some parts with geographic or meteorological factors. This work presents the first SITW map in China, which sets up a benchmark for further stable isotopes research across China. This is a critical step toward monitoring and investigating water resources in climate-sensitive regions, so the human-hydrological system. These findings could be used in the future to establish water management strategies at a national or regional scale. Title: Divergence of stable isotopes in tap water across China Authors: Zhao, SH; Hu, HC; Tian, FQ; Tie, Q; Wang, LX; Liu, YL; Shi, CX Source: SCIENTIFIC REPORTS, 7 10.1038/srep43653 MAR 2 2017

  12. MixSIAR: advanced stable isotope mixing models in R (United States)

    Background/Question/Methods The development of stable isotope mixing models has coincided with modeling products (e.g. IsoSource, MixSIR, SIAR), where methodological advances are published in parity with software packages. However, while mixing model theory has recently been ex...


    Stream water quality and quantity depend on discharge rates of water and nutrients from soils. However, soil-water storage is very dynamic and strongly influenced by plants. We analyzed stable isotopes of oxygen and hydrogen to quantify spatial and temporal changes in evaporati...

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

    DEFF Research Database (Denmark)

    Li, Miling; Sherman, Laura S; Blum, Joel D


    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 me...

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

    Indian Academy of Sciences (India)

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

  16. Stable isotope systematics of surface water bodies in the Himalayan ...

    Indian Academy of Sciences (India)

    Stable hydrogen (D) and oxygen (18O) isotope ratios of the headwaters of the Indus and its tributaries, surface ice in glaciers, saline and fresh water lakes and thermal springs in the Himalayan and Trans- Himalayan (Kashmir) region are reported. The D-18O relationship for the river samples shows a slope of 9.12 ...

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

    African Journals Online (AJOL)

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

  18. What can Fe stable isotopes tell us about magmas?

    DEFF Research Database (Denmark)

    Stausberg, Niklas

    in magmas, Fe. Fe isotope compositions of magmatic rocks exhibit systematic differences, where the heaviest compositions are found in rhyolites and granites. Understanding of these systematics is complicated by a lack of constraints on Fe isotope fractionation among minerals and liquids under magmatic...... the differentiation of magmas from the perspective of Fe stable isotopes, integrated with petrology, by studying igneous rocks and their constituent phases (minerals and glasses) from the Bushveld Complex, South Africa, Thingmuli, Iceland, Pantelleria, Italy, and the Bishop Tuff, USA. The findings are interpreted...... in terms of available theory, experiments and forward modeling incorporating petrologic constraints. Mafic cumulate rocks from the Bushveld Complex exhibit resolvable whole rock Fe isotopic variation with modal mineralogy and mineral composition, to a 1st order reflecting partitioning of Fe3+ and Fe2...

  19. Application of heavy stable isotopes in forensic isotope geochemistry: A review

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Jugdeep [W.M. Keck Isotope Laboratory, Department of Earth Sciences, University of California, Santa Cruz, CA 95064 (United States)], E-mail:; Habicht-Mauche, Judith; Juarez, Chelsey [Department of Anthropology, University of California, Santa Cruz, CA 95064 (United States)


    Light stable isotopes have been used for many years to characterize the source and transport of materials. More recently heavy isotope systems such as Sr, Nd and Pb have been added to this list in order to aid source identification. With the advent of multiple collector ICP-MS, the range of isotopic tools now available has increased considerably, however, until the isotope systematics of these new non-traditional isotope systems have become better understood, they will not be as useful in characterizing material source and transportation. Applications using heavy metal stable isotopes (mostly traditional heavy isotopes) have reached most avenues in science, including earth sciences, archaeology, anthropology, animal physiology, ecology and toxicology. This field will continue to grow as new applications are developed and techniques become simpler and quicker. This paper provides a review of how this field has grown and presents two new applications using Pb and Sr isotopes in glazes to determine the source of ore used in glazes, and using Sr isotopes to determine the origin of undocumented deceased Mexican border crossers.

  20. Dual carbon-chlorine stable isotope investigation of sources and fate of chlorinated ethenes in contaminated groundwater. (United States)

    Wiegert, Charline; Aeppli, Christoph; Knowles, Tim; Holmstrand, Henry; Evershed, Richard; Pancost, Richard D; Macháčková, Jiřina; Gustafsson, Örjan


    Chlorinated ethenes (CEs) are ubiquitous groundwater contaminants, yet there remains a need for a method to efficiently monitor their in situ degradation. We report here the first field application of combined stable carbon and chlorine isotope analysis of tetrachloroethene (PCE) and trichloroethene (TCE) to investigate their biodegradation in a heavily contaminated aquifer. The two-dimensional Compound Specific Isotope Analysis (2D-CSIA) approach was facilitated by a recently developed gas chromatography-quadrupole mass spectrometry (GCqMS) method for δ(37)Cl determination. Both C and Cl isotopes showed evidence of ongoing PCE transformation. Applying published C isotope enrichment factors (ε(C)) enabled evaluation of the extent of in situ PCE degradation (11-78%). We interpreted C and Cl isotopes using a numerical reactive transport model along a 60-m flow path. It revealed that combined PCE and TCE mass load was dechlorinated by less than 10%, and that cis-dichloroethene was not further dechlorinated. Furthermore, the 2D-CSIA approach allowed estimation of Cl isotope enrichment factors ε(Cl) (-7.8 to -0.8‰) and characteristic ε(Cl)/ε(C) values (0.42-1.12) for reductive PCE dechlorination at this field site. This investigation demonstrates the benefit of 2D-CSIA to assess in situ degradation of CEs and the applicability of Cl isotope fractionation to evaluate PCE and TCE dechlorination.

  1. Stable Isotope Mapping of Alaskan Grasses and Marijuana (United States)

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


    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. δ13C, δ15N and δ18O 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

  2. Interpretation of benthic foraminiferal stable isotopes in subtidal estuarine environments

    Directory of Open Access Journals (Sweden)

    Y.-M. Paulet


    Full Text Available Here we present a novel approach for the interpretation of stable isotope signatures recorded in benthic foraminifera from subtidal estuarine environments. The stable isotopic composition (δ18O and δ13C of living Ammonia tepida and Haynesina germanica is examined at four stations in the Auray River estuary (Gulf of Morbihan, France sampled in two contrasting seasons, spring 2006 and winter 2007. Comparing benthic foraminiferal δ18O measurements with theoretical oxygen isotopic equilibrium values, calculated on the basis of water temperature and salinity measurements in the upper and lower estuary, i.e., T-S-δ18Oeq. diagrams, strongly suggests that foraminiferal faunas sampled at the four stations calcified during different periods of the year. This interpretation can be refined by using the benthic foraminiferal δ13C, which is mainly determined by the mixing of sea and river water. In the upper estuary foraminifera mainly calcified in early spring and winter, whereas in the lower estuary calcification mainly took place in spring, summer and autumn. This new method provides insight into the complexity of estuarine benthic foraminiferal stable isotope records. In addition, it can also be used to obtain new information on preferred calcification periods of benthic foraminiferal taxa in different parts of the estuary.

  3. Stable isotope labeling for proteomic analysis of tissues in mouse. (United States)

    Hölper, Soraya; Ruhs, Aaron; Krüger, Marcus


    Since the first metabolic labeling experiments with stable isotopes beginning of the last century, several approaches were pursued to monitor protein dynamics in living animals. Today, almost all model organisms from bacteria to rodents can be fully labeled with SILAC (stable isotope labeling of amino acids in cell culture) amino acids. The development of special media and diets containing the labeled amino acids provides an efficient way to metabolically label prokaryotic and eukaryotic organisms. Preferentially, the essential amino acid lysine ((13)C6-lysine) is used to label mice (Mus musculus) and after one generation the natural isotope is fully replaced by the stable (13)C6-lysine isotope. So far, the SILAC mouse approach has been used to analyze several transgenic and knockout mouse models. Spike-in of labeled proteins into non-labeled samples provides an accurate relative protein quantification method without any chemical modification. Here we describe how to establish a SILAC mouse colony and describe the analysis of skeletal muscle tissue with different metabolic and contractile profiles.

  4. BOREAS TE-5 CO2 Concentration and Stable Isotope Composition (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry


    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. This data set contains measurements of the concentration and stable carbon (C-13/C-12 and oxygen (O-18/O-16) isotope ratios of atmospheric CO2 in air samples collected at different heights within forest canopies. The data were collected to determine the influence of photosynthesis and respiration by the forest ecosystems on the concentration and stable isotope ratio of atmospheric CO2 These measurements were collected at the SSA during each 1994 IFC at OJP, OBS, and OA sites. Measurements were also collected at the NSA during each 1994 IFC at the OJP, T6R5S TE UBS, and T2Q6A TE OA sites. The stable isotope ratios are expressed using standard delta notation and in units of per mil. The isotope ratios are expressed relative to the international standard, PDB, for both carbon and oxygen samples. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  5. Stable isotope measurements of evapotranspiration partitioning in a maize field (United States)

    Hogan, Patrick; Parajka, Juraj; Oismüller, Markus; Strauss, Peter; Heng, Lee; Blöschl, Günter


    Evapotranspiration (ET) is one of the most important processes in describing land surface - atmosphere interactions as it connects the energy and water balances. Furthermore knowledge of the individual components of evapotranspiration is important for ecohydrological modelling and agriculture, particularly for irrigation efficiency and crop productivity. In this study, we tested the application of the stable isotope method for evapotranspiration partitioning to a maize crop during the vegetative stage, using sap flow sensors as a comparison technique. Field scale ET was measured using an eddy covariance device and then partitioned using high frequency in-situ measurements of the isotopic signal of the canopy water vapor. The fraction of transpiration (Ft) calculated with the stable isotope method showed good agreement with the sap flow method. High correlation coefficient values were found between the two techniques, indicating the stable isotope method can successfully be applied in maize. The results show the changes in transpiration as a fraction of evapotranspiration after rain events and during the subsequent drying conditions as well as the relationship between transpiration and solar radiation and vapor pressure deficit.

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

    Directory of Open Access Journals (Sweden)

    A. Kornilova


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

  7. Infrared Spectroscopy and Stable Isotope Geochemistry of Hydrous Silicate Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Stolper, Edward


    The focus of this DOE-funded project has been the study of volatile components in magmas and the atmosphere. Over the twenty-one year period of this project, we have used experimental petrology and stable isotope geochemistry to study the behavior and properties of volatile components dissolved in silicate minerals and melts and glasses. More recently, we have also studied the concentration and isotopic composition of CO2 in the atmosphere, especially in relation to air quality issues in the Los Angeles basin.

  8. Bulk and compound-specific isotope analysis of long-chain n-alkanes from a 85,000 year sediment core from Lake Peten Petén Itzá, Guatemala (United States)

    Mays, J.; Brenner, M.; Curtis, J. H.; Curtis, K.; Hodell, D. A.; Correa-Metrio, A.; Escobar, J.; Dutton, A. L.; Zimmerman, A. R.; Guilderson, T. P.


    Sediment core PI-6 from Lake Petén Itzá, Guatemala possesses an 85-ka record of climate from lowland Central America. Variations in sediment lithology suggest large, abrupt changes in precipitation during the last glacial and deglacial periods, and into the early Holocene. Study of cores from nearby Lake Quexil demonstrated the utility of using the carbon isotopic composition of leaf wax n-alkanes to infer changes in terrestrial vegetation (Huang et al. 2001). Forty-nine samples were taken from composite Petén Itzá core PI-6 to measure carbon isotopes of bulk organic carbon and long-chain n alkanes. Changes in δ13C values indicate shifts in the relative proportion of C3 to C4 biomass. The record shows largest δ13C variations are associated with Heinrich Events. Carbon isotope values in sediments deposited during the Last Glacial Maximum (LGM) indicate moderate precipitation and little rainfall fluctuation. The deglacial was a period of pronounced climate variability, e.g. the Bölling-Allerod and Younger Dryas. Arid times of the deglacial were inferred from samples with the greatest δ13C values in organic matter, reflecting the largest proportion of C4 plants. Such inferences are supported by stable isotope measurements on ostracod shells and analysis of pollen from the same sample depths in core PI-6. Carbon stable isotope measures on bulk organic carbon and n alkane compounds show similar trends throughout the record and the C:N ratio of Petén Itzá sediments indicates a predominantly allochthonous source for bulk organic matter. Hence, isotope measures on bulk organic carbon (δ13CTOC) in sediments from this lake are sufficient to infer climate-driven shifts in vegetation, making n-alkane extraction and isotope analysis superfluous.

  9. Characteristics of stable carbon isotopic composition of shale gas

    Directory of Open Access Journals (Sweden)

    Zhenya Qu


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

  10. Water vapor stable isotope observations from tropical Australia

    KAUST Repository

    Parkes, Stephen


    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

  11. Identifying Seasonal Groundwater Recharge Using Environmental Stable Isotopes

    Directory of Open Access Journals (Sweden)

    Hsin-Fu Yeh


    Full Text Available In this study, the stable isotope values of oxygen and hydrogen were used to identify the seasonal contribution ratios of precipitation to groundwater recharge in the Hualien River basin of eastern Taiwan. The differences and correlations of isotopes in various water bodies were examined to evaluate the groundwater recharge sources for the Hualian River basin and the interrelations between groundwater and surface water. Proportions of recharge sources were calculated based on the results of the mass balance analysis of the isotope composition of hydrogen and oxygen in the basin. Mountain river water accounted for 83% and plain rainfall accounted for 17% of the groundwater recharge in the Huanlian River basin. Using the mean d-values, a comparison of d-values of precipitation and groundwater indicates the groundwater consists of 75.5% wet seasonal sources and 24.5% dry seasonal sources, representing a distinct seasonal variation of groundwater recharge in the study area. Comparisons between hydrogen and oxygen isotopes in rainwater showed that differences in the amount of rainfall resulted in depleted oxygen and hydrogen isotopes for precipitation in wet seasons as compared to dry seasons. The river water contained more depleted hydrogen and oxygen isotopes than was the case for precipitation, implying that the river water mainly came from the upstream catchment. In addition, the hydrogen and oxygen isotopes in the groundwater slightly deviated from the hydrogen and oxygen isotopic meteoric water line in Huanlian. Therefore, the groundwater in this basin might be a mixture of river water and precipitation, resulting in the effect of the river water recharge being greater than that of rainfall infiltration.

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

    DEFF Research Database (Denmark)

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


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

  13. Stable isotopic composition of water vapor in the tropics (United States)

    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.


    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 δ18O values approached isotopic equilibrium with seawater during quiescent weather or in regions of isolated or disorganized convection. Lowest δ18O 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 δ18O value of vapor over the sea surface therefore decreases as storm activity and organization increases.

  14. Stable Isotopes of Ice: the Legacy of Willi Dansgaard (United States)

    White, J. W. C.; Johnson, S. J.


    Stable isotope ratios of ice, D/H and 18O/16O are one of the key climate indicators measured in ice cores. These isotope ratios vary with temperature, a relationship based on physical principles backed up by many observations. The combination of these isotope ratios, expressed as the difference between the delta values with δ18O scaled by a factor of eight, is called the deuterium excess (d=δD-8*δ18O). This parameter varies primarily as a function of the conditions of evaporation of the parent moisture for snow, yielding a signal of ocean conditions measured in the ice. In his classic 1964 paper in Tellus, Willi Dansgaard laid out the theoretical and observational basis for using stable isotope ratios in ice cores as paleo-environmental tools. This paper, cited over 2,200 times, and written nearly 50 years ago, is one of the key foundational papers in paleoclimatology, and remains a must read for any student of stable isotope geochemistry. In this talk we will explore Dansgaard's legacy of ice core climatology, with a focus on his pioneering work in using the full temporal resolution of ice cores in Greenland to explore climate change on time scales of years to decades. While Dansgaard began his career applying a clever technique to a novel medium with the goal of simply trying to understand how our planet functions, he early on understood the power of ice cores to inform us about human impacts on the climate system, as well as the power of ice cores to tell us about natural climate variability on time scales of human interest and impact. Dansgaard's body of work is one of the solid pillars on which modern paleoclimatology stands, and continues to inform us today about modern anthropogenic climate change.

  15. Fractionation of Stable Isotopes in Atmospheric Aerosol Reactions

    DEFF Research Database (Denmark)

    Meusinger, Carl

    Aerosols - particles suspended in air - are the single largest uncertainty in our current understanding of Earth's climate. They also affect human health, infrastructure and ecosystems. Aerosols are emitted either directly into the atmosphere or are formed there for instance in response to chemical...... reactions and undergo complex chemical and physical changes during their lifetimes. In order to assess processes that form and alter aerosols, information provided by stable isotopes can be used to help constrain estimates on the strength of aerosol sources and sinks. This thesis studies (mass......-independent) fractionation processes of stable isotopes of C, N, O and S in order to investigate three different systems related to aerosols: 1. Post-depositional processes of nitrate in snow that obscure nitrate ice core records 2. Formation and aging of secondary organic aerosol generated by ozonolysis of X...

  16. Ciguatera toxins in the food chain revealed by stable isotopes. (United States)

    Winter, A; Tosteson, T R


    The stable carbon and nitrogen isotope contents of the meat tissues of 27 identifiable fish found in the gut contents of 70 ciguatoxic and non-ciguatoxic barracuda caught along the southwest coast of Puerto Rico have been analyzed. The isotope ratios of those fish found in the stomach contents of ciguatoxic barracuda were significantly different than ratios determined in those fish found in the stomachs of non-ciguatoxic barracuda. The isotope ratios of the toxic dinoflagellate Ostreopsis lenticularis, a presumed vector of ciguatera in the Caribbean were found to be extremely light, particularly for nitrogen. The lightened nitrogen ratios of the herbivore (Doctorfish) and carnivore (Squirrelfish) fishes found in the stomach contents of ciguatoxic barracuda suggest that the dinoflagellate was in the food chain of these barracuda. Results indicate that the trophic pathway of ciguatoxins through the marine food chain from the presumed primary trophic level (dinoflagellates/bacteria) to ciguatoxic barracuda appears to be different than the pathway to non-toxic barracuda. Stable isotope ratios may be a very useful tool for tracing ciguatoxins in the food chain and the identification of ciguatoxic fish.

  17. Stable isotope reference materials at the IAEA - the latest developments. (United States)

    Assonov, Sergey; Gröning, Manfred; Fajgelj, Ales


    During the last few years the IAEA has performed works in several directions as following: • Released IAEA-603 (replacement of NBS19) - this is primary Stable isotope Reference Material (RM) used for the VPDB 13C and 18O scale realisation, • Released 6 isotopically enriched (in 2H and 18O) waters, • Performed careful monitoring of LVEC' property delta-13C value. This resulted in understanding that LSVEC needs a replacement. • Taken part in characterisation of 18 new organic CRMs (together with Indiana University and USGS) • Creating collaborations with metrology institutes - focus on metrological aspects of RMs, • As a spin-off of the Technical Meeting on Stable Isotope Reference Materials (IAEA, Vienna 2014) the European EMPIR project aimed to create infrastructure to produce gas mixtures characterised in CO2 isotope composition has been established (NPL, UK and other metrological institutes). The presentation will give details of these works and overview of the current status of RMs production and development.

  18. Development of Laser Application Technology for Stable Isotope Production

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Do Young; Ko, Kwang Hoon; Kwon, Duck Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)] (and others)


    Tl-203 is used as a source material to produce Tl-201 radioisotope which is produced in a cyclotron by irradiating the enriched Tl-203 target. Tl-201 is a radiopharmaceutical for SPECT (single photon emission computerized tomography) to diagnose heart diseases and tumors. This Project aim to develop laser application technology to product stable isotopes such as Tl-203, Yb-168, and Yb-176. For this, photoion extraction device, atomic beam generator, dye lasers, and high power IR lasers are developed.

  19. An attempt to use stable isotopes in clam spoilage assessment


    Aníbal, J.


    Clams...One of the most popular and profitable molluscs exploited in rearing plots in the Mediterranean, used as a food source for centuries. Usually seafood and clam intoxications can have 3 origins: Toxins DSP, PSP, NSP, ASP Microorganisms Clostridium, Listeria, Vibrio, Escherichia, Salmonella,Spoiled food… Goal of this study: assess the potential use of carbon and nitrogen stable isotopes as spoilage indicators for clams (Ruditapes decussatus), in order to better understand and assess t...

  20. Stable isotopes differentiate bottlenose dolphins off west-central Florida (United States)

    Barros, Nélio B.; Ostrom, P. H.; Stricker, Craig A.; Wells, R.S.


    Distinguishing discrete population units among continuously distributed coastal small cetaceans is challenging and crucial to conservation. We evaluated the utility of stable isotopes in assessing group membership in bottlenose dolphins (Tursiops truncatus) off west-central Florida by analyzing carbon, nitrogen, and sulfur isotope values (δ13C, δ15N, and δ34S) of tooth collagen from stranded dolphins. Individuals derived from three putative general population units: Sarasota Bay (SB), nearshore Gulf of Mexico (GULF), and offshore waters (OFF). Animals of known history (SB) served to ground truth the approach against animals of unknown history from the Gulf of Mexico (GULF, OFF). Dolphin groups differed significantly for each isotope. Average δ13C values from SB dolphins (−10.6‰) utilizing sea grass ecosystems differed from those of GULF (−11.9‰) and OFF (−11.9‰). Average δ15N values of GULF (12.7‰) and OFF (13.2‰) were higher than those of SB dolphins (11.9‰), consistent with differences in prey trophic levels. δ34S values showed definitive differences among SB (7.1‰), GULF (11.3‰), and OFF (16.5‰) dolphins. This is the first application of isotopes to population assignment of bottlenose dolphins in the Gulf of Mexico and results suggest that isotopes may provide a powerful tool in the conservation of small cetaceans.

  1. Stable Isotope Systematics of Coalbed Gas during Desorption and Production

    Directory of Open Access Journals (Sweden)

    Martin Niemann


    Full Text Available The stable carbon isotope ratios of coalbed methane (CBM demonstrate diagnostic changes that systematically vary with production and desorption times. These shifts can provide decisive, predictive information on the behaviour and potential performance of CBM operations. Samples from producing CBM wells show a general depletion in 13C-methane with increasing production times and corresponding shifts in δ13C-CH4 up to 35.8‰. Samples from canister desorption experiments show mostly enrichment in 13C for methane with increasing desorption time and isotope shifts of up to 43.4‰. Also, 13C-depletion was observed in some samples with isotope shifts of up to 32.1‰. Overall, the magnitudes of the observed isotope shifts vary considerably between different sample sets, but also within samples from the same source. The δ13C-CH4 values do not have the anticipated signature of methane generated from coal. This indicates that secondary processes, including desorption and diffusion, can influence the values. It is also challenging to deconvolute these various secondary processes because their molecular and isotope effects can have similar directions and/or magnitudes. In some instances, significant alteration of CBM gases has to be considered as a combination of secondary alteration effects.

  2. Estimation of evapotranspiration rate in irrigated lands using stable isotopes (United States)

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


    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.

  3. Realistic Fasting Does Not Affect Stable Isotope Levels of a Metabolically Efficient Salamander (United States)

    Stable isotopes are commonly used to examine various aspects of animal ecology. The use of stable isotopes generally proceeds under the implicit assumption that resource use is the only factor driving variation in stable isotope levels; however, a wealth of studies demonstrate a...

  4. Climatic signals in multiple highly resolved stable isotope records from Greenland

    DEFF Research Database (Denmark)

    Vinther, Bo Møllesøe; Dahl-Jensen, Dorthe; Johnsen, Sigfus Johann


    are found to correspond better with winter stable isotope data than with summer or annual average stable isotope data it is suggested that a strong local Greenland temperature signal can be extracted from the winter stable isotope data even on centennial to millennial time scales. Udgivelsesdato: Feb....

  5. Enantioselective stable isotope analysis (ESIA) of polar Herbicides (United States)

    Maier, Michael; Qiu, Shiran; Elsner, Martin


    The complexity of aquatic systems makes it challenging to assess the environmental fate of chiral micropolutants. As an example, chiral herbicides are frequently detected in the environment (Buser and Muller, 1998); however, hydrological data is needed to determine their degradability from concentration measurements. Otherwise declining concentrations cannot unequivocally be attributed to degradation, but could also be caused by dilution effects. In contrast, isotope ratios or enantiomeric ratios are elegant alternatives that are independent of dilution and can even deliver insights into reaction mechanisms. To combine the advantages of both approaches we developed an enatioselective stable isotope analysis (ESIA) method to investigate the fate of the chiral herbicides 4-CPP ((RS)-2-(4-chlorophenoxy)-propionic acid), mecoprop (2-(4-Chloro-2-methylphenoxy)-propionic acid) and dichlorprop (2-(2,4-Dichlorophenoxy)-propionic acid). After testing the applicable concentration range of the method, enantioselective isotope fractionation was investigated by microbial degradation using dichlorprop as a model compound. The method uses enantioselective gas-chromatography (GC) to separate enantiomers. Subsequently samples are combusted online to CO2 and carbon isotope ratios are determined for each enantiomer by isotope-ratio-mass-spectrometry (IRMS). Because the analytes contain a polar carboxyl-group, samples were derivatised prior to GC-IRMS analysis with methanolic BF3 solution. Precise carbon isotope analysis (2σ ≤0.5‰) was achieved with a high sensitivity of ≥ 7 ng C that is needed on column for one analysis. Microbial degradation of the model compound dichlorprop was conducted with Delftia acidovorans MC1 and pronounced enantiomer fractionation, but no isotope fractionation was detected. The absence of isotope fractionation can be explained by two scenarios: either the degrading enzyme has no isotopic preference, or another step in the reaction without an isotopic

  6. [Lipid metabolism and lipogenesis: application of stable isotopes]. (United States)

    Martínez, J A; Martí, A


    Fat metabolism is regulated by several neuroendocrine and nutritional factors, which affect equilibrium between lipogenesis and lipolysis. Lipid utilization and fate in the organism can be assessed by in vivo and in vitro methods by measuring the rate of the different metabolic pathways (dynamic aspects), but also the net balance which may lead to fat accumulation or loss (static aspects). The quantitation of synthesis and breakdown reactions can be performed by using different tracers such as radioactive and stable isotopes. Fatty acid synthesis can be independently measured by the intravenous infusion of 13C acetate and application of the MIDA technique. In brief, this method uses probability analysis to measure the synthesis of biological polymers. It is based on the mathematical principle that the labeling pattern of a polymer synthesized from a stable-isotopically labeled precursor will conform to a predicted binomial or multinomial expansion. Thus, the isotopic enrichment of the precursor pool is calculated from measurements on the product alone. In the case of fatty acid synthesis, the proportions of excess (above natural background abundance) of single-labeled and double labeled (EM1 and EM2 species respectively) are a function of the probability (p) that the precursor subunits were isotopically labeled. Using this value of P for the isotopic enrichment of the acetylCoA pool, the theoretical 13C enrichment in the fatty acid if 100% were newly formed from this acetate pool is calculated. The actual isotopic enrichment is measured by gas chromatography-mass spectrometry (GCMS). This value divided by the theoretical maximum value equals the fraction of the fatty acid that is newly formed (f). The value for f represents dilution of de novo synthesized fatty acid by non-de novo sources. This method requires that newly synthesized (labeled) and preformed (unlabeled) mix in the liver and communicate with plasma VLDL over the period of the isotope infusion. It also

  7. Magnesium stable isotope ecology using mammal tooth enamel. (United States)

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


    Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (δ(13)C) 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 (δ(44)Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (δ(26)Mg) 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 δ(26)Mg, δ(13)C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that δ(26)Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this (26)Mg enrichment up the trophic chain is due to a (26)Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using δ(26)Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel δ(26)Mg 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.

  8. Stable isotope signatures of large herbivore foraging habitats across Europe. (United States)

    Hofman-Kamińska, Emilia; Bocherens, Hervé; Borowik, Tomasz; Drucker, Dorothée G; Kowalczyk, Rafał


    We investigated how do environmental and climatic factors, but also management, affect the carbon (δ13C) and nitrogen (δ15N) stable isotope composition in bone collagen of the two largest contemporary herbivores: European bison (Bison bonasus) and moose (Alces alces) across Europe. We also analysed how different scenarios of population recovery- reintroduction in bison and natural recovery in moose influenced feeding habitats and diet of these two species and compared isotopic signatures of modern populations of bison and moose (living in human-altered landscapes) with those occurring in early Holocene. We found that δ13C of modern bison and moose decreased with increasing forest cover. Decreasing forest cover, increasing mean annual temperature and feeding on farm crops caused an increase in δ15N in bison, while no factor significantly affected δ15N in moose. We showed significant differences in δ13C and δ15N among modern bison populations, in contrast to moose populations. Variation in both isotopes in bison resulted from inter-population differences, while in moose it was mainly an effect of intra-population variation. Almost all modern bison populations differed in δ13C and δ15N from early Holocene bison. Such differences were not observed in moose. It indicates refugee status of European bison. Our results yielded evidence that habitat structure, management and a different history of population recovery have a strong influence on foraging behaviour of large herbivores reflected in stable isotope signatures. Influence of forest structure on carbon isotope signatures of studied herbivores supports the "canopy effect" hypothesis.

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

    Directory of Open Access Journals (Sweden)

    Otto Appenzeller

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

  10. The stable isotope ecology of Pan in Uganda and beyond. (United States)

    Loudon, James E; Sandberg, Paul A; Wrangham, Richard W; Fahey, Babette; Sponheimer, Matt


    Stable isotope analysis has long been used to study the dietary ecology of living and fossil primates, and there has been increasing interest in using stable isotopes to study primate habitat use and anthropogenic impacts on non-human primates. Here, we examine the stable carbon and nitrogen isotope compositions of chimpanzees (Pan troglodytes) from seven communities in Uganda across a continuum of habitat structure (closed to more open) and access to anthropogenic resources (no reliance to heavy reliance). In general, the hair δ(13) C, but not δ(15) N, values of these communities vary depending on forest structure and degree of anthropogenic influence. When integrated with previously published hair δ(13) C and δ(15) N values for Pan, it is apparent that modern "savanna" and "forest" Pan form discrete clusters in carbon and nitrogen isotope space, although there are exceptions probably relating to microhabitat specialization. The combined dataset also reveals that Pan δ(13) C values (but not δ(15) N values) are inversely related to rainfall (r(2)  = 0.62). We converted Pan hair δ(13) C values to enamel equivalents and made comparisons to the fossil hominoids Sivapithecus sp., Gigantopithecus blacki, Ardipithecus ramidus, and Australopithecus anamensis. The δ(13) C values of the fossil hominins Ar. ramidus and Au. anamensis do not cluster with the δ(13) C values of modern Pan in "forest" habitats, or with fossil hominoids that are believed to have inhabited forests. Am. J. Primatol. 78:1070-1085, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  11. Stable isotope-resolved metabolomics and applications for drug development (United States)

    Fan, Teresa W-M.; Lorkiewicz, Pawel; Sellers, Katherine; Moseley, Hunter N.B.; Higashi, Richard M.; Lane, Andrew N.


    Advances in analytical methodologies, principally nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS), during the last decade have made large-scale analysis of the human metabolome a reality. This is leading to the reawakening of the importance of metabolism in human diseases, particularly cancer. The metabolome is the functional readout of the genome, functional genome, and proteome; it is also an integral partner in molecular regulations for homeostasis. The interrogation of the metabolome, or metabolomics, is now being applied to numerous diseases, largely by metabolite profiling for biomarker discovery, but also in pharmacology and therapeutics. Recent advances in stable isotope tracer-based metabolomic approaches enable unambiguous tracking of individual atoms through compartmentalized metabolic networks directly in human subjects, which promises to decipher the complexity of the human metabolome at an unprecedented pace. This knowledge will revolutionize our understanding of complex human diseases, clinical diagnostics, as well as individualized therapeutics and drug response. In this review, we focus on the use of stable isotope tracers with metabolomics technologies for understanding metabolic network dynamics in both model systems and in clinical applications. Atom-resolved isotope tracing via the two major analytical platforms, NMR and MS, has the power to determine novel metabolic reprogramming in diseases, discover new drug targets, and facilitates ADME studies. We also illustrate new metabolic tracer-based imaging technologies, which enable direct visualization of metabolic processes in vivo. We further outline current practices and future requirements for biochemoinformatics development, which is an integral part of translating stable isotope-resolved metabolomics into clinical reality. PMID:22212615

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

    NARCIS (Netherlands)

    Stellaard, F; Elzinga, H


    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

  13. Stable isotope ratio analysis for authentication of lamb meat. (United States)

    Piasentier, E; Valusso, R; Camin, F; Versini, G


    The effectiveness of the analysis of stable isotope ratios ((13)C/(12)C and (15)N/(14)N) in fractions of lamb meat, measured by isotope ratio mass spectrometry, was evaluated as a method of feeding and geographical origin authentication. Analyses were carried out on meat from 12 lamb types, produced in couples in six European countries (country of origin, CO) and divided in three groups according to the feeding regime during their finishing period: suckled milk only, pasture without any solid supplementation and supplementation containing maize grain (feeding regime, FR). These analyses were made on two samples of longissimus thoracis muscle, taken from the 13th rib section of the left side of two different lambs, randomly chosen between the 120 selected to represent each lamb type. δ(13)C values varied significantly in different meat fractions, the difference being higher in protein than in fat (average difference 5.0‰). However, the pairs δ(13)C values of crude fat and protein were highly correlated (r=0.976) and affected by lamb type in a similar fashion, mainly reflecting animals' feeding regime. Even δ(15)N values of meat protein fraction showed significant differences between lamb types, not dependant on the feeding regime. In fact, lambs fed on similar diets, but in different countries, gave meat with different (15)N relative abundances. These findings provide the possibility of discriminating lamb types within the same feeding regime. Canonical discriminant analysis was carried out to evaluate whether lamb meat from different CO or FR or CO×FR interaction could be mathematically distinguished by its stable isotope ratios. On the basis of CO, the corrected empirical allocation of 79.2% of the initial observations and the corrected cross-validation of two thirds of the individual meat samples was obtained. FR gave better results: 91.7% of the individual meat samples was both correctly allocated and cross-validated, indicating the high potential of

  14. Assessing sources of human methylmercury exposure using stable mercury isotopes. (United States)

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


    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 δ(202)Hg values between pilot whale muscle tissue and Faroese whalers' hair but no mass-independent fractionation. We found a similar offset in δ(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 Δ(199)Hg and δ(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.

  15. Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Benech, H


    The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

  16. Using phylogenetic probes for quantification of stable isotope labeling and microbial community analysis (United States)

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


    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).

  17. Methodology for the Validation of Isotopic Analyses by Mass Spectrometry in Stable-Isotope Labeling Experiments. (United States)

    Heuillet, Maud; Bellvert, Floriant; Cahoreau, Edern; Letisse, Fabien; Millard, Pierre; Portais, Jean-Charles


    Stable-isotope labeling experiments (ILEs) are widely used to investigate the topology and operation of metabolic networks. The quality of isotopic data collected in ILEs is of utmost importance to ensure reliable biological interpretations, but current evaluation approaches are limited due to a lack of suitable reference material and relevant evaluation criteria. In this work, we present a complete methodology to evaluate mass spectrometry (MS) methods used for quantitative isotopic studies of metabolic systems. This methodology, based on a biological sample containing metabolites with controlled labeling patterns, exploits different quality metrics specific to isotopic analyses (accuracy and precision of isotopologue masses, abundances, and mass shifts and isotopic working range). We applied this methodology to evaluate a novel LC-MS method for the analysis of amino acids, which was tested on high resolution (Orbitrap operating in full scan mode) and low resolution (triple quadrupole operating in multiple reaction monitoring mode) mass spectrometers. Results show excellent accuracy and precision over a large working range and revealed matrix-specific as well as mode-specific characteristics. The proposed methodology can identify reliable (and unreliable) isotopic data in an easy and straightforward way and efficiently supports the identification of sources of systematic biases as well as of the main factors that influence the overall accuracy and precision of measurements. This approach is generic and can be used to validate isotopic analyses on different matrices, analytical platforms, labeled elements, or classes of metabolites. It is expected to strengthen the reliability of isotopic measurements and thereby the biological value of ILEs.

  18. NMR-based Stable Isotope Resolved Metabolomics in systems biochemistry. (United States)

    Lane, Andrew N; Fan, Teresa W-M


    Metabolism is the basic activity of live cells, and monitoring the metabolic state provides a dynamic picture of the cells or tissues, and how they respond to external changes, for in disease or treatment with drugs. NMR is an extremely versatile analytical tool that can be applied to a wide range of biochemical problems. Despite its modest sensitivity its versatility make it an ideal tool for analyzing biochemical dynamics both in vitro and in vivo, especially when coupled with its isotope editing capabilities, from which isotope distributions can be readily determined. These are critical for any analyses of flux in live organisms. This review focuses on the utility of NMR spectroscopy in metabolomics, with an emphasis on NMR applications in stable isotope-enriched tracer research for elucidating biochemical pathways and networks with examples from nucleotide biochemistry. The knowledge gained from this area of research provides a ready link to genomic, epigenomic, transcriptomic, and proteomic information to achieve systems biochemical understanding of living cells and organisms. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Stable isotope signatures reflect dietary diversity in European forest moths. (United States)

    Adams, Marc-Oliver; Seifert, Carlo Lutz; Lehner, Lisamarie; Truxa, Christine; Wanek, Wolfgang; Fiedler, Konrad


    Information on larval diet of many holometabolous insects remains incomplete. Carbon (C) and nitrogen (N) stable isotope analysis in adult wing tissue can provide an efficient tool to infer such trophic relationships. The present study examines whether moth feeding guild affiliations taken from literature are reflected in isotopic signatures. Non-metric multidimensional scaling and permutational analysis of variance indicate that centroids of dietary groups differ significantly. In particular, species whose larvae feed on mosses or aquatic plants deviated from those that consumed vascular land plants. Moth δ(15)N signatures spanned a broader range, and were less dependent on species identity than δ(13)C values. Comparison between moth samples and ostensible food sources revealed heterogeneity in the lichenivorous guild, indicating only Lithosia quadra as an obligate lichen feeder. Among root-feeding Agrotis segetum, some specimens appear to have developed on crop plants in forest-adjacent farm land. Reed-feeding stem-borers may partially rely on intermediary trophic levels such as fungal or bacterial growth. Diagnostic partitioning of moth dietary guilds based on isotopic signatures alone could not be achieved, but hypotheses on trophic relationships based on often vague literature records could be assessed with high resolution. Hence, the approach is well suited for basic categorization of moths where diet is unknown or notoriously difficult to observe (i.e. Microlepidoptera, lichen-feeders).

  20. Advances in stable isotope assisted labeling strategies with information science. (United States)

    Kigawa, Takanori


    Stable-isotope (SI) labeling of proteins is an essential technique to investigate their structures, interactions or dynamics by nuclear magnetic resonance (NMR) spectroscopy. The assignment of the main-chain signals, which is the fundamental first step in these analyses, is usually achieved by a sequential assignment method based on triple resonance experiments. Independently of the triple resonance experiment-based sequential assignment, amino acid-selective SI labeling is beneficial for discriminating the amino acid type of each signal; therefore, it is especially useful for the signal assignment of difficult targets. Various combinatorial selective labeling schemes have been developed as more sophisticated labeling strategies. In these strategies, amino acids are represented by combinations of SI labeled samples, rather than simply assigning one amino acid to one SI labeled sample as in the case of conventional amino acid-selective labeling. These strategies have proven to be useful for NMR analyses of difficult proteins, such as those in large complex systems, in living cells, attached or integrated into membranes, or with poor solubility. In this review, recent advances in stable isotope assisted labeling strategies will be discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Stable isotope dilution analysis of the fusarium mycotoxin zearalenone. (United States)

    Cramer, Benedikt; Bretz, Michael; Humpf, Hans-Ulrich


    Zearalenone is a secondary metabolite produced by molds of the Fusarium genus. Beside its nonsteroidal molecular structure, zearalenone has estrogenic activity and can disrupt the function of the endogenous hormone 17beta-estradiol in animals and possibly in humans. It can frequently be found in all major cereal grains as well as in processed food. Because of the estrogenic properties of zearalenone and its metabolites, legal regulations are installed in the European Union setting maximum levels in cereals and cereal products. Routine analysis of zearalenone in various commodities is carried out by HPLC with fluorescence detection, but due to the development of multi-mycotoxin methods and the reduced sample cleanup, HPLC-MS/MS has become a fast and efficient alternative. However, to achieve a reliable quantitation with this technique suitable internal standards are required. This paper reports the synthesis of stable isotope labeled 3,5- d 2-zearalenone (ZON) as internal standard for stable isotope dilution analysis. Furthermore, a method for the analysis of zearalenone by HPLC-MS/MS using 3,5- d 2-zearalenone as IS has been developed. Fifteen cereal products from the German retail markets were analyzed, of which seven contained ZON in levels from 4.9 to 45.0 microg/kg.

  2. Compound-Specific δ¹⁵N and δ¹³C Analyses of Amino Acids for Potential Discrimination between Organically and Conventionally Grown Wheat. (United States)

    Paolini, Mauro; Ziller, Luca; Laursen, Kristian Holst; Husted, Søren; Camin, Federica


    We present a study deploying compound-specific nitrogen and carbon isotope analysis of amino acids to discriminate between organically and conventionally grown plants. We focused on grain samples of common wheat and durum wheat grown using synthetic nitrogen fertilizers, animal manures, or green manures from nitrogen-fixing legumes. The measurement of amino acid δ(15)N and δ(13)C values, after protein hydrolysis and derivatization, was carried out using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Our results demonstrated that δ(13)C of glutamic acid and glutamine in particular, but also the combination of δ(15)N and δ(13)C of 10 amino acids, can improve the discrimination between conventional and organic wheat compared to stable isotope bulk tissue analysis. We concluded that compound-specific stable isotope analysis of amino acids represents a novel analytical tool with the potential to support and improve the certification and control procedures in the organic sector.

  3. Comparison of gas chromatography/isotope ratio mass spectrometry and liquid chromatography/isotope ratio mass spectrometry for carbon stable-isotope analysis of carbohydrates. (United States)

    Moerdijk-Poortvliet, Tanja C W; Schierbeek, Henk; Houtekamer, Marco; van Engeland, Tom; Derrien, Delphine; Stal, Lucas J; Boschker, Henricus T S


    We compared gas chromatography/isotope ratio mass spectrometry (GC/IRMS) and liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) for the measurement of δ(13)C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although LC/IRMS is expected to be more accurate and precise, no direct comparison has been reported. GC/IRMS with the aldonitrile penta-acetate (ANPA) derivatisation method was compared with LC/IRMS without derivatisation. A large number of glucose standards and a variety of natural samples were analysed for five neutral carbohydrates at natural abundance as well as at (13)C-enriched levels. Gas chromatography/chemical ionisation mass spectrometry (GC/CIMS) was applied to check for incomplete derivatisation of the carbohydrate, which would impair the accuracy of the GC/IRMS method. The LC/IRMS technique provided excellent precision (±0.08‰ and ±3.1‰ at natural abundance and enrichment levels, respectively) for the glucose standards and this technique proved to be superior to GC/IRMS (±0.62‰ and ±19.8‰ at natural abundance and enrichment levels, respectively). For GC/IRMS measurements the derivatisation correction and the conversion of carbohydrates into CO2 had a considerable effect on the measured δ(13)C values. However, we did not find any significant differences in the accuracy of the two techniques over the full range of natural δ(13)C abundances and (13)C-labelled glucose. The difference in the performance of GC/IRMS and LC/IRMS diminished when the δ(13)C values were measured in natural samples, because the chromatographic performance and background correction became critical factors, particularly for LC/IRMS. The derivatisation of carbohydrates for the GC/IRMS method was complete. Although both LC/IRMS and GC/IRMS are reliable techniques for compound-specific stable carbon isotope analysis of carbohydrates (provided that derivatisation is complete and the

  4. Multivariate Stable Isotope Analysis to Determine Linkages between Benzocaine Seizures (United States)

    Kemp, H. F.; Meier-Augenstein, W.; Collins, M.; Salouros, H.; Cunningham, A.; Harrison, M.


    In July 2010, a woman was jailed for nine years in the UK after the prosecution successfully argued that attempting to import a cutting agent was proof of involvement in a conspiracy to supply Cocaine. That landmark ruling provided law enforcement agencies with much greater scope to tackle those involved in this aspect of the drug trade, specifically targeting those importing the likes of benzocaine or lidocaine. Huge quantities of these compounds are imported into the UK and between May and August 2010, four shipments of Benzocaine amounting to more then 4 tons had been seized as part of Operation Kitley, a joint initiative between the UK Border Agency and the Serious Organised Crime Agency (SOCA). By diluting cocaine, traffickers can make it go a lot further for very little cost, leading to huge profits. In recent years, dealers have moved away from inert substances, like sugar and baby milk powder, in favour of active pharmaceutical ingredients (APIs), including anaesthetics like Benzocaine and Lidocaine. Both these mimic the numbing effect of cocaine, and resemble it closely in colour, texture and some chemical behaviours, making it easier to conceal the fact that the drug has been diluted. API cutting agents have helped traffickers to maintain steady supplies in the face of successful interdiction and even expand the market in the UK, particularly to young people aged from their mid teens to early twenties. From importation to street-level, the purity of the drug can be reduced up to a factor of 80 and street level cocaine can have a cocaine content as low as 1%. In view of the increasing use of Benzocaine as cutting agent for Cocaine, a study was carried out to investigate if 2H, 13C, 15N and 18O stable isotope signatures could be used in conjunction with multivariate chemometric data analysis to determine potential linkage between benzocaine exhibits seized from different locations or individuals to assist with investigation and prosecution of drug

  5. Lake Van carbonates: Implications for lacustrine stable isotope analysis (United States)

    McCormack, Jeremy; Immenhauser, Adrian; Kwiecien, Ola


    Carbonate stable isotope (δ18O and δ13C) analysis is a commonly applied and powerful proxy in lacustrine palaeoclimatology. In the absence of large quantities of detrital carbonates, the bulk carbonate is assumed to mainly represent inorganic carbonates precipitated in the epilimnion. In well-preserved, geologically young sediments (e.g. varves), post-depositional processes affecting the mineralogy or geochemistry of sedimentary carbonates are difficult to recognise. In case of terminal and alkaline Lake Van, the interpretation of the δ18O and δ13C signals of bulk carbonates is, in comparison to other proxies, far from straightforward when relying on traditional interpretative approaches. Consequently, using a multi-component approach we studied, individually and in detail, various components comprising Lake Van's bulk carbonates. Samples investigated here cover the last glacial/interglacial period. Inorganic ( 63 μm) carbonates were isolated by wet-sieving and analysed by means of XRD, SEM and isotope mass spectrometry. High-resolution mineralogical analysis revealed variable amounts of aragonite and calcite as well as early diagenetic non-stoichiometric (calcian) dolomite. The early diagenetic dolomite appears to be replacing the inorganic aragonite/calcite and occurs within finely-laminated, organic-rich sediments. Isotopically the dolomite differs significantly from the primary carbonates with typically heavier δ18O and lighter δ13C values. Thus, in the case of bulk sediment isotope analysis the presence of higher amounts of diagenetic dolomite is distorting the isotopic pattern. Ostracod valves represent biogenic carbonates. However, apart from well-preserved, translucent carapaces we have found coated ones, reoccurring throughout the profile within specific facies types. The coating, comprising mainly of aragonite has a significantly heavier δ18O and δ13C signature compared to coeval inorganic carbonates, precipitated presumably in the surface water

  6. Expanding the isotopic toolbox: Applications of hydrogen and oxygen stable isotope ratios to food web studies

    Directory of Open Access Journals (Sweden)

    Hannah B Vander Zanden


    Full Text Available The measurement of stable carbon (δ13C and nitrogen (δ15N isotopes in tissues of organisms has formed the foundation of isotopic food web reconstructions, as these values directly reflect assimilated diet. In contrast, stable hydrogen (δ2H and oxygen (δ18O isotope measurements have typically been reserved for studies of migratory origin and paleoclimate reconstruction based on systematic relationships between organismal tissue and local environmental water. Recently, innovative applications using δ2H and, to a lesser extent, δ18O values have demonstrated potential for these elements to provide novel insights in modern food web studies. We explore the advantages and challenges associated with three applications of δ2H and δ18O values in food web studies. First, large δ2H differences between aquatic and terrestrial ecosystem end members can permit the quantification of energy inputs and nutrient fluxes between these two sources, with potential applications for determining allochthonous vs. autochthonous nutrient sources in freshwater systems and relative aquatic habitat utilization by terrestrial organisms. Next, some studies have identified a relationship between δ2H values and trophic position, which suggests that this marker may serve as a trophic indicator, in addition to the more commonly used δ15N values. Finally, coupled measurements of δ2H and δ18O values are increasing as a result of reduced analytical challenges to measure both simultaneously and may provide additional ecological information over single element measurements. In some organisms, the isotopic ratios of these two elements are tightly coupled, whereas the isotopic disequilibrium in other organisms may offer insight into the diet and physiology of individuals. Although a coherent framework for interpreting δ2H and δ18O data in the context of food web studies is emerging, many fundamental uncertainties remain. We highlight directions for targeted research that

  7. Stable isotope tracking of endangered sea turtles: validation with satellite telemetry and δ15N analysis of amino acids.

    Directory of Open Access Journals (Sweden)

    Jeffrey A Seminoff

    Full Text Available Effective conservation strategies for highly migratory species must incorporate information about long-distance movements and locations of high-use foraging areas. However, the inherent challenges of directly monitoring these factors call for creative research approaches and innovative application of existing tools. Highly migratory marine species, such as marine turtles, regularly travel hundreds or thousands of kilometers between breeding and feeding areas, but identification of migratory routes and habitat use patterns remains elusive. Here we use satellite telemetry in combination with compound-specific isotope analysis of amino acids to confirm that insights from bulk tissue stable isotope analysis can reveal divergent migratory strategies and within-population segregation of foraging groups of critically endangered leatherback sea turtles (Dermochelys coriacea across the Pacific Ocean. Among the 78 turtles studied, we found a distinct dichotomy in δ(15N values of bulk skin, with distinct "low δ(15N" and "high δ(15N" groups. δ(15N analysis of amino acids confirmed that this disparity resulted from isotopic differences at the base of the food chain and not from differences in trophic position between the two groups. Satellite tracking of 13 individuals indicated that their bulk skin δ(15N value was linked to the particular foraging region of each turtle. These findings confirm that prevailing marine isoscapes of foraging areas can be reflected in the isotopic compositions of marine turtle body tissues sampled at nesting beaches. We use a Bayesian mixture model to show that between 82 and 100% of the 78 skin-sampled turtles could be assigned with confidence to either the eastern Pacific or western Pacific, with 33 to 66% of all turtles foraging in the eastern Pacific. Our forensic approach validates the use of stable isotopes to depict leatherback turtle movements over broad spatial ranges and is timely for establishing wise conservation

  8. Stable nitrogen isotopes in coastal macroalgae: Geographic and anthropogenic variability

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Inés G., E-mail:; Bode, Antonio


    Growing human population adds to the natural nitrogen loads to coastal waters. Both anthropogenic and natural nitrogen is readily incorporated in new biomass, and these different nitrogen sources may be traced by the measurement of the ratio of stable nitrogen isotopes (δ{sup 15}N). In this study δ{sup 15}N was determined in two species of macroalgae (Ascophyllum nodosum and Fucus vesiculosus), and in nitrate and ammonium to determine the relative importance of anthropogenic versus natural sources of nitrogen along the coast of NW Spain. Both algal species and nitrogen sources showed similar isotopic enrichment for a given site, but algal δ{sup 15}N was not related to either inorganic nitrogen concentrations or δ{sup 15}N in the water samples. The latter suggests that inorganic nitrogen inputs are variable and do not always leave an isotopic trace in macroalgae. However, a significant linear decrease in macroalgal δ{sup 15}N along the coast is consistent with the differential effect of upwelling. Besides this geographic variability, the influence of anthropogenic nitrogen sources is evidenced by higher δ{sup 15}N in macroalgae from rias and estuaries compared to those from open coastal areas and in areas with more than 15 × 10{sup 3} inhabitants in the watershed. These results indicate that, in contrast with other studies, macroalgal δ{sup 15}N is not simply related to either inorganic nitrogen concentrations or human population size but depends on other factors as the upwelling or the efficiency of local waste treatment systems. - Highlights: ► Anthropogenic versus upwelling nitrogen effect on macroalgal δ{sup 15}N was studied. ► The influence of populations and upwelling has not been made before on macroalgal δ{sup 15}N. ► Natural variability has not been taken into account in most biomonitoring studies. ► Upwelling explains most of the variability in δ{sup 15}N in macroalgae.

  9. A New Stable Isotope Record From the Subantarctic Southeastern Pacific (United States)

    Waddell, L. M.; Hendy, I. L.; Moore, T. C.; Lyle, M. W.


    Few stable isotope records exist from the southeast Pacific Ocean due to its remote location, low sedimentation rates, and shallow carbonate compensation depth (CCD). The CCD in the southeast Pacific, however, has been found to be unusually deep (~4750 m), thereby allowing for the preservation of Neogene carbonates at abyssal depths. Herein we present stable isotope results from MV0502-4JC, which was recently recovered from the subantarctic region of the Southwest Pacific (50°20S, 148°08W, 4286 m). Dating the record with radiolarian biostratigraphy, we have generated a benthic stable isotope record back to the Middle Miocene from Cibicidoides spp. and a planktic record from Globigerina bulloides into the Late Pliocene. These stable isotope records, in conjunction with carbonate contents and counts of ice-rafted debris (IRD) and manganese micronodules show the effect of global ice sheet build up on this poorly understood region. A prominent negative δ13C shift of ~1‰ (from ~1 to ~0.2‰) in the benthic record occurs at ~15.3 MBSF (Middle Miocene) as carbonate contents in the core decrease from ~80% to ~20%, and significant changes in the bottom water are indicated by changes in the dominant Cibicidoides spp. at the site from C. robertsonianus to C. wuellerstorfi. Trace amounts of IRD and abundant manganese micronodules also appear at the site at this time. A significant hiatus (from the Late Miocene to the Middle Pliocene) occurs somewhere between 11.4 and 9.8 MBSF. From 9.8 to 8 MBSF (Late Pliocene) benthic δ18O increases and δ13C decreases by ~1‰. Also, IRD increases, manganese micronodules decrease, and there is a dramatic increase in the preservation of planktic foraminifera at the site. A planktic δ13C shift of >1‰ (from 0 to 1‰) occurs at ~5 MBSF (Pleistocene) coincident with a 20% increase in carbonate concentration. After this interval, the variability in both benthic δ18O and δ13C and planktic δ18O increases significantly. We interpret the

  10. Changes in stable isotope composition in Lake Michigan trout ... (United States)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, Sergey S.


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

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

    Directory of Open Access Journals (Sweden)

    Xueshu Xie

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

  13. On the Effect of Planetary Stable Isotope Compositions on Growth and Survival of Terrestrial Organisms. (United States)

    Xie, Xueshu; Zubarev, Roman A


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

  14. Quantification of petrogenic PAH in marine sediment using molecular stable carbon isotopic ratio measurement

    Energy Technology Data Exchange (ETDEWEB)

    Mazeas, L.; Budzinski, H. [Bordeaux-1 Univ., 33 - Talence (France). Laboratoire de Physico- et Toxico-Chimie des Systemes Naturels


    Compound-specific carbon isotope analyses were performed on polycyclic aromatic hydrocarbons (phenanthrene and methyl-phenanthrene) isolated from marine sediments contaminated with petroleum. Isotopic composition measurements of individual methyl-phenanthrene were subject to important uncertainties because they were not completely separated by gas chromatographic separation. Nevertheless the isotopic composition of the sum of methyl-phenanthrene was measured with good reproducibility. As petrogenic PAHs and PAHs present in the sediment before the petroleum contamination have different isotopic compositions it was possible to quantitatively source apportion methyl-phenanthrene in contaminated sediment with a good precision and reliability, using the isotopic composition of the sum of methyl-phenanthrene and a simple mass balance calculation. (authors) 10 refs.

  15. Quantifying nitrogen process rates in a constructed wetland using natural abundance stable isotope signatures and stable isotope amendment experiments. (United States)

    Erler, Dirk V; Eyre, Bradley D


    This study describes the spatial variability in nitrogen (N) transformation within a constructed wetland (CW) treating domestic effluent. Nitrogen cycling within the CW was driven by settlement and mineralization of particulate organic nitrogen and uptake of NO3-. The concentration of NO3- was found to decrease, as the delta15N-NO3- signature increased, as water flowed through the CW, allowing denitrification rates to be estimated on the basis of the degree of fractionation of delta15N-NO3-. Estimates of denitrification hinged on the determination of a net isotope effect (eta), which was influenced byprocesses that enrich or deplete 15NO3- (e.g., nitrification), as well as the rate constants associated with the different processes involved in denitrification (i.e., diffusion and enzyme activity). The influence of nitrification on eta was quantified; however, it remained unclear how eta varied due to variability in denitrification rate constants. A series of stable isotope amendment experiments was used to further constrain the value of eta and calculate rates of denitrification, and nitrification, within the wetland. The maximum calculated rate of denitrification was 956 +/- 187 micromol N m(-2) h(-1), and the maximum rate of nitrification was 182 +/- 28.9 micromol N m(-2) h(-1). Uptake of NO3- was quantitatively more important than denitrification throughoutthe wetland. Rates of N cycling varied spatially within thewetland, with denitrification dominating in the downstream deoxygenated region of the wetland. Studies that use fractionation of N to derive rate estimates must exercise caution when interpreting the net isotope effect. We suggest a sampling procedure for future natural abundance studies that may help improve the accuracy of N cycling rate estimates.

  16. Stable isotope customer list and summary of shipments. FY 1976, July 1, 1975--September 30, 1976

    Energy Technology Data Exchange (ETDEWEB)

    Davis, W. C. [comp.


    This compilation is for those concerned with the separation and sale of stable isotopes. The information is divided into four sections: domestic and foreign customers; isotopes, cross-referenced to customer numbers; states and countries, cross-referenced to customer numbers; and tabulation of the shipments, quantities, and dollars for domestic, foreign, and project categories for each isotope. (DLC)

  17. A Teaching Exercise to Introduce Stable Isotope Fractionation of Metals into Geochemistry Courses (United States)

    Weiss, Dominik J.; Harris, Caroline; Maher, Kate; Bullen, Thomas


    Variations in the isotopic composition of elements have been widely used to study earth's climate, biosphere, and interior, and more recently to track the fate of contaminants. Within the broad range of elements that exhibit measureable isotopic variations, metal stable isotopes are increasingly applied across the biological, geological,…

  18. Laboratory and field methods for stable isotope analysis in human biology. (United States)

    Reitsema, Laurie J


    Stable isotope analysis (SIA; carbon, hydrogen, nitrogen, sulfur, and oxygen) of human tissues offers a means for assessing diet among living humans. Stable isotope ratios of broad categories of food and drink food vary systematically, and stable isotope ratios in consumer tissues represent a composite of the isotopic ratios of food and drink consumed during an individual's life. Isotopic evidence for diet is independent of errors in informant recall, and accrues during time periods when researchers are absent. Beyond diet reconstruction, tissue stable isotope ratios are sensitive to excursions from homeostasis, such as starvation and rapid growth. Because of their relationship to diet, geographic location, hydration, and nutritional status, stable isotope signatures in human tissues offer a window into human biocultural adaptations, past and present. This article describes methods for SIA that may be usefully applied in studies of living humans, with emphasis placed on carbon and nitrogen. Some of the ecological, physiological, and evolutionary applications of stable isotope data among living humans are discussed. By incorporating SIA in research, human biologists facilitate a productive dialog with bioarchaeologists, who routinely use stable isotope evidence, mingling different perspectives on human biology and behavior. © 2015 Wiley Periodicals, Inc.

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

    Directory of Open Access Journals (Sweden)

    Ana G Popa-Lisseanu

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

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

    NARCIS (Netherlands)

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


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

  1. IsoBank – Stable isotope ecology in the age of ‘Big Data’ (United States)

    Stable isotopes ratios provide valuable information to fish biologists working in a diverse range of fields: e.g. ecologists, population biologists and fishery managers. Ecologists take advantage of stable isotope ratios to provide information on the diet and migration history of consumers or when a...

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

    NARCIS (Netherlands)

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


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

  3. Fractionation of the stable isotopes of inorganic carbon by seagrasses. (United States)

    Benedict, C R; Wong, W W; Wong, J H


    The delta(13)C values for seagrasses collected along the Texas Gulf Coast range from -10.9 to -11.4 per thousand. These values are similar to the delta(13)C values of terrestrial C(4) plants, but seagrasses lack bundle sheath cells which are important in determining the delta(13)C values of C(4) plants. This work attempts to explain the reason the delta(13)C values of seagrasses resemble the delta(13)C values of C(4) plants.Investigations on the photosynthetic characteristics of seagrasses show that dissolved CO(2) is the species of inorganic carbon absorbed or accumulated by Thalassia testudinum. The rate of photosynthetic CO(2) fixation varies from 9.6 to 129.0 micromoles CO(2) per milligram chlorophyll per hour in the presence of 0.042 to 1.9 millimolar dissolved CO(2) due to the high resistances of Thalassia leaves to CO(2) diffusion. Phosphoglyceric acid is the first stable product of photosynthetic CO(2) fixation in Thalassia which is a Calvin cycle plant. The light/dark ratios of (14)CO(2) release from submerged Thalassia leaf sections at 1, 21, and 100% O(2) indicate a small apparent photorespiration. Dark respiration continues in the light and is stimulated by 21 and 100% O(2). The low apparent photorespiration may be due to membrane and H(2)O resistances to CO(2) diffusion with subsequent refixation of the photorespired CO(2). The internal pool of CO(2) is not in equilibrium with the external pool of CO(2) which results in a closed system in the seagrasses.The delta(13)C value of CO(2) in sea H(2)O in isotopic equilibrium with HCO(3) (-) is -10.3 per thousand and the delta(13)C value of hexoses isolated from the leaves of Thalassia is -11.5 per thousand. In the closed system of the seagrasses there is a -1.2 per thousand fractionation of CO(2) by ribulose-1,5-bisphosphate carboxylase and the Calvin cycle. This contrasts to a fractionation of about -17 to -27 per thousand of the stable carbon isotopes of CO(2) by the Calvin cycle in the open system of

  4. Stable water isotope patterns in a climate change hotspot: the isotope hydrology framework of Corsica (western Mediterranean). (United States)

    van Geldern, Robert; Kuhlemann, Joachim; Schiebel, Ralf; Taubald, Heinrich; Barth, Johannes A C


    The Mediterranean is regarded as a region of intense climate change. To better understand future climate change, this area has been the target of several palaeoclimate studies which also studied stable isotope proxies that are directly linked to the stable isotope composition of water, such as tree rings, tooth enamel or speleothems. For such work, it is also essential to establish an isotope hydrology framework of the region of interest. Surface waters from streams and lakes as well as groundwater from springs on the island of Corsica were sampled between 2003 and 2009 for their oxygen and hydrogen isotope compositions. Isotope values from lake waters were enriched in heavier isotopes and define a local evaporation line (LEL). On the other hand, stream and spring waters reflect the isotope composition of local precipitation in the catchment. The intersection of the LEL and the linear fit of the spring and stream waters reflect the mean isotope composition of the annual precipitation (δP) with values of-8.6(± 0.2) ‰ for δ(18)O and-58(± 2) ‰ for δ(2)H. This value is also a good indicator of the average isotope composition of the local groundwater in the island. Surface water samples reflect the altitude isotope effect with a value of-0.17(± 0.02) ‰ per 100 m elevation for oxygen isotopes. At Vizzavona Pass in central Corsica, water samples from two catchments within a lateral distance of only a few hundred metres showed unexpected but systematic differences in their stable isotope composition. At this specific location, the direction of exposure seems to be an important factor. The differences were likely caused by isotopic enrichment during recharge in warm weather conditions in south-exposed valley flanks compared to the opposite, north-exposed valley flanks.

  5. Stable isotope analysis of safety matches using isotope ratio mass spectrometry--a forensic case study. (United States)

    Farmer, N L; Meier-Augenstein, W; Kalin, R M


    Isotope ratio mass spectrometry (IRMS) was used to assess what contribution the technique could make towards the comparative analysis of matchstick samples within the 'normal' framework of a forensic investigation. A method was developed to allow the comparison of samples submitted as a result of an investigation, with the added advantage of rapid sample turn-around expected within this field. To the best of our knowledge this is the first time that wooden safety matches have been analysed using IRMS. In this particular case, bulk stable isotope analysis carrried out on a 'like-for-like' basis could demonstrate conclusively that matches seized from a suspect were different from those collected at the scene of crime. The maximum delta13C variability observed within one box was 2.5 per thousand, which, in conjunction with the error of measurement, was regarded to yield too wide an error margin as to permit differentiation of matchsticks based on 13C isotopic composition alone given that the 'natural' 13C abundance in wood ranges from -20 to -30 per thousand. However, from the delta2H values obtained for crime scene matches and seized matches of -114.5 per thousand and -65 per thousand, respectively, it was concluded that the matches seized were distinctly different from those collected at the crime scene. Copyright (c) 2005 John Wiley & Sons, Ltd.

  6. Status of stable isotope enrichment, products, and services at the Oak Ridge National Laboratory (United States)

    Scott Aaron, W.; Tracy, Joe G.; Collins, Emory D.


    The Oak Ridge National Laboratory (ORNL) has been supplying enriched stable and radioactive isotopes to the research, medical, and industrial communities for over 50 y. 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 to be 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; ISO 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 capablities 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.

  7. Stable Isotope Characteristics of Akiri Vein Copper Mineralization ...

    African Journals Online (AJOL)

    The Akiri vein copper mineralization was investigated for its carbon and oxygen isotopic composition to determine the characteristics of the mineralizing fluid. Carbon and oxygen isotope analyses of Akiri siderite range between δ13C values (-1.05 to -1.71‰) and δ13O values (-14.94 to -15.18) respectively. δ 13C isotopic ...

  8. Latitudinal Trends in Stable Isotope Signatures of Northeast Atlantic Rhodoliths (United States)

    Hofmann, Laurie


    Rhodoliths are free-living calcifying red algae that form extensive beds in shallow marine benthic environments (plasticity of dissolved inorganic carbon (DIC) uptake mechanisms of rhodoliths along a latitudinal gradient in the Northeast (NE) Atlantic using natural stable isotope signatures. The delta 13C signature of macroalgae can be used to provide an indication of the preferred inorganic carbon source (CO2 vs. HCO3-). Here we present the total and organic delta 13C signatures of NE Atlantic rhodoliths with respect to changing temperature and light along the latitudinal gradient from the Canary Islands to Spitsbergen. A decreasing trend in delta 13C signatures with increasing latitude suggests that rhodoliths rely solely on CO2 as an inorganic carbon source at mid latitudes, while those at low latitudes may be able to utilize HCO3-. Polar rhodoliths deviate from this trend, suggesting they may have unique physiological mechanisms related to inorganic carbon acquisition and assimilation, which may have important implications for calcification in an environment undergoing rapid changing ocean chemistry.

  9. Development of a stable isotope dilution assay for tenuazonic acid. (United States)

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


    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 μg/kg and a limit of quantitation of 0.3 μg/kg. Recovery was close to 100% in the range of 3-300 μg/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 μg/kg (tomato ketchup, n = 9), 363 and 909 μg/kg (tomato paste, n = 2), and 8 and 247 μg/kg (pureed tomatoes and comparable products, n = 5).

  10. Stable isotope studies of nicotine kinetics and bioavailability

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  11. NMR-based stable isotope resolved metabolomics in systems biochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Teresa W-M. [University of Louisville, Department of Chemistry (United States); Lane, Andrew N., E-mail: [University of Louisville, Center for Regulatory Environmental Analytical Metabolomics (United States)


    An important goal of metabolomics is to characterize the changes in metabolic networks in cells or various tissues of an organism in response to external perturbations or pathologies. The profiling of metabolites and their steady state concentrations does not directly provide information regarding the architecture and fluxes through metabolic networks. This requires tracer approaches. NMR is especially powerful as it can be used not only to identify and quantify metabolites in an unfractionated mixture such as biofluids or crude cell/tissue extracts, but also determine the positional isotopomer distributions of metabolites derived from a precursor enriched in stable isotopes such as {sup 13}C and {sup 15}N via metabolic transformations. In this article we demonstrate the application of a variety of 2-D NMR editing experiments to define the positional isotopomers of compounds present in polar and non-polar extracts of human lung cancer cells grown in either [U-{sup 13}C]-glucose or [U-{sup 13}C,{sup 15}N]-glutamine as source tracers. The information provided by such experiments enabled unambiguous reconstruction of metabolic pathways, which is the foundation for further metabolic flux modeling.

  12. Stable isotope analysis of Dacryoconarid carbonate microfossils: a new tool for Devonian oxygen and carbon isotope stratigraphy. (United States)

    Frappier, Amy Benoit; Lindemann, Richard H; Frappier, Brian R


    Dacryoconarids are extinct marine zooplankton known from abundant, globally distributed calcite microfossils in the Devonian, but their shell stable isotope composition has not been previously explored. Devonian stable isotope stratigraphy is currently limited to less common invertebrates or bulk rock analyses of uncertain provenance. As with Cenozoic planktonic foraminifera, isotopic analysis of dacryoconarid shells could facilitate higher-resolution, geographically widespread stable isotope records of paleoenvironmental change, including marine hypoxia events, climate changes, and biocrises. We explored the use of Dacryoconarid isotope stratigraphy as a viable method in interpreting paleoenvironments. We applied an established method for determining stable isotope ratios (δ(13) C, δ(18) O values) of small carbonate microfossils to very well-preserved dacryoconarid shells. We analyzed individual calcite shells representing five common genera using a Kiel carbonate device coupled to a MAT 253 isotope ratio mass spectrometer. Calcite shell δ(13) C and δ(18) O values were compared by taxonomic group, rock unit, and locality. Single dacryoconarid calcite shells are suitable for stable isotope analysis using a Kiel-IRMS setup. The dacryoconarid shell δ(13) C values (-4.7 to 2.3‰) and δ(18) O values (-10.3 to -4.8‰) were consistent across taxa, independent of shell size or part, but varied systematically through time. Lower fossil δ(18) O values were associated with warmer water temperature and more variable δ(13) C values were associated with major bioevents. Dacryoconarid δ(13) C and δ(18) O values differed from bulk rock carbonate values. Dacryoconarid individual microfossil δ(13) C and δ(18) O values are highly sensitive to paleoenvironmental changes, thus providing a promising avenue for stable isotope chemostratigraphy to better resolve regional to global paleoceanographic changes throughout the upper Silurian to the upper Devonian. Our results

  13. Stable isotope and modelling evidence that CO2 drives vegetation changes in the tropics (United States)

    Bragg, F. J.; Prentice, I. C.; Harrison, S. P.; Eglinton, G.; Foster, P. N.; Rommerskirchen, F.; Rullkötter, J.


    Atmospheric CO2 concentration is hypothesized to influence vegetation distribution via tree-grass competition, with higher CO2 concentrations favouring trees. The stable carbon isotope (δ13C) signature of vegetation is influenced by the relative importance of C4 plants (including most tropical grasses) and C3 plants (including nearly all trees), and the degree of stomatal closure - a response to aridity - in C3 plants. Compound-specific δ13C analyses of leaf-wax biomarkers in sediment cores of an offshore South Atlantic transect are used here as a record of vegetation changes in subequatorial Africa. These data suggest a large increase in C3 relative to C4 plant dominance after the Last Glacial Maximum. Using a process-based biogeography model that explicitly simulates 13C discrimination, we show that climate change alone cannot explain the observed shift in δ13C values. The physiological effect of increasing CO2 concentration is decisive, altering the C3 / C4 balance and bringing the simulated and observed δ13C values into line. It is concluded that CO2 concentration itself was a key agent of tropical vegetation change during the last glacial-interglacial transition. Two additional inferences follow. First, long-term variations in terrestrial δ13C values are not simply a proxy for regional rainfall as has sometimes been assumed. Such interpretations need to be re-examined. Second, rising CO2 concentration today is likely to be influencing tree-grass competition in a similar way, and thus contributing to the "woody thickening" observed in savannas worldwide. This second inference points to the importance of experiments to determine how vegetation composition in savannas is likely to be influenced by the continuing rise in CO2 concentration.

  14. Shifts in rotifer life history in response to stable isotope enrichment: testing theories of isotope effects on organismal growth. (United States)

    Gorokhova, Elena


    In ecology, stable isotope labelling is commonly used for tracing material transfer in trophic interactions, nutrient budgets and biogeochemical processes. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism growth and metabolism. This assumption is, however, challenged by theoretical considerations and experimental studies on kinetic isotope effects in vivo. Here, I demonstrate profound changes in life histories of the rotifer Brachionus plicatilis fed 15N-enriched algae (0.4-5.0 at%); i.e. at the enrichment levels commonly used in ecological studies. These findings support theoretically predicted effects of heavy isotope enrichment on growth, metabolism and ageing in biological systems and underline the importance of accounting for such effects when using stable isotope labelling in experimental studies.

  15. Stable isotope ratios of rain and vapor in 1995 hurricanes (United States)

    Lawrence, James Robert; Gedzelman, Stanley David; Zhang, Xiaoping; Arnold, Robert


    Isotope ratios of rain and vapor samples collected at the surface from four tropical cyclones during the active 1995 Atlantic hurricane season were determined. A two-dimensional bulk microphysics isotope model was applied to steady symmetric tropical cyclones to explain the observed low mean values and inward decrease of isotope ratios of the rain and vapor. The low mean value is caused by the tropical cyclone's relatively large size, longevity, and deep clouds. The inward decrease is due to diffusive isotope exchange between falling rain and converging vapor in the atmospheric boundary layer. Dean, a minimal tropical storm, produced relatively high isotope ratios because of its small size and youth. Rains from the extreme outer edge of Felix, a category 3 hurricane, exhibited high isotope ratios similar to normal summer rain. Isotope ratios of rains and vapors from Hurricane Luis in Puerto Rico decreased as the storm approached. Isotope ratios of rain exhibited an abrupt jump from low values in the eastern half of Puerto Rico to high values farther west which is linked to the storm's rainbands. Isotope ratios of Hurricane Opal's rains reflected the storm's asymmetric structure, with lowest values west of the point of landfall. Record low isotope ratios from a squall line that struck eastern Texas two days before landfall are linked to low-level outflow from Opal and demonstrate that hurricanes can vent enormous quantities of vapor to the surroundings.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  17. High frequency, realtime measurements of stable isotopes in liquid water (United States)

    Weiler, M.; Herbstritt, B.; Gralher, B.


    We developed a method to measure in-situ the isotopic composition of liquid water with minimal supervision and, most important, with a temporal resolution of less than a minute. For this purpose a off-the-shelf microporous hydrophobic membrane contactor for under 200€ was combined with an isotope laser spectrometer (Picarro). The contactor, originally designed for degassing liquids, was used with nitrogen as carrier gas in order to transform a small fraction of liquid water to water vapor. The generated water vapor was then analyzed continuously by the isotope laser spectrometer. To prove the membrane's applicability we determined the specific isotope fractionation factor for the phase change through the contactor's membrane for a common temperature range and with different waters of known isotopic compositions. This fractionation factor is then used to derive the liquid water isotope ratio from the measured water vapor isotope ratios and the measured temperature at the phase change. The system was compared for breakthrough curves of isotopically enriched water and the isotope values corresponded very well with those of liquid water samples taken simultaneously and analyzed with a conventional method (CRDS). The introduced method supersedes taking liquid samples and employs only relative cheap and readily available components. This makes it a relatively inexpensive, fast, user-friendly and easily reproducible method. It can be applied in both the field and laboratory wherever a water vapor isotope analyzer can be run and whenever real-time isotope data of liquid water are required at high temporal resolution with the same accuracy as collecting individual water samples.

  18. Stable carbon and oxygen isotope study on benthic foraminifera ...

    Indian Academy of Sciences (India)

    Isotopic fractionations are mainly controlled by ontogeny, bottom/pore water chemistry, habitat preference, kinetic effect and respiration. ... Infaunal species (B. marginata, Ammonia spp. and N. auris) show a lighter carbon isotopic excursion with respect to the epifaunal to shallow infaunal forms (C. wuellerstorfi, ...

  19. Spatiotemporal variation of stable isotopic composition in precipitation

    DEFF Research Database (Denmark)

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


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

  20. Stable isotopic variation in tropical forest plants for applications in primatology. (United States)

    Blumenthal, Scott A; Rothman, Jessica M; Chritz, Kendra L; Cerling, Thure E


    Stable isotope analysis is a promising tool for investigating primate ecology although nuanced ecological applications remain challenging, in part due to the complex nature of isotopic variability in plant-animal systems. The aim of this study is to investigate sources of carbon and nitrogen isotopic variation at the base of primate food webs that reflect aspects of primate ecology. The majority of primates inhabit tropical forest ecosystems, which are dominated by C3 vegetation. We used stable isotope ratios in plants from Kibale National Park, Uganda, a well-studied closed-canopy tropical forest, to investigate sources of isotopic variation among C3 plants related to canopy stratification, leaf age, and plant part. Unpredictably, our results demonstrate that vertical stratification within the canopy does not explain carbon or nitrogen isotopic variation in leaves. Leaf age can be a significant source of isotopic variation, although the direction and magnitude of this difference is not consistent across tree species. Some plant parts are clearly differentiated in carbon and nitrogen isotopic composition, particularly leaves compared to non-photosynthetic parts such as reproductive parts and woody stem parts. Overall, variation in the isotopic composition of floral communities, plant species, and plant parts demonstrates that stable isotope studies must include analysis of local plant species and parts consumed by the primates under study from within the study area. Am. J. Primatol. 78:1041-1054, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  1. Enzymatic synthesis and RNA interference of nucleosides incorporating stable isotopes into a base moiety. (United States)

    Hatano, Akihiko; Shiraishi, Mitsuya; Terado, Nanae; Tanabe, Atsuhiro; Fukuda, Kenji


    Thymidine phosphorylase was used to catalyze the conversion of thymidine (or methyluridine) and uracil incorporating stable isotopes to deoxyuridine (or uridine) with the uracil base incorporating the stable isotope. These base-exchange reactions proceeded with high conversion rates (75-96%), and the isolated yields were also good (64-87%). The masses of all synthetic compounds incorporating stable isotopes were identical to the theoretical molecular weights via EIMS. (13)C NMR spectra showed spin-spin coupling between (13)C and (15)N in the synthetic compounds, and the signals were split, further proving incorporation of the isotopes into the compounds. The RNA interference effects of this siRNA with uridine incorporating stable isotopes were also investigated. A 25mer siRNA had a strong knockdown effect on the MARCKS protein. The insertion position and number of uridine moieties incorporating stable isotopes introduced into the siRNA had no influence on the silencing of the target protein. This incorporation of stable isotopes into RNA and DNA has the potential to function as a chemically benign tracer in cells. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Continuous in situ measurements of stable isotopes in liquid water (United States)

    Herbstritt, Barbara; Gralher, Benjamin; Weiler, Markus


    We developed a method to measure in situ the isotopic composition of liquid water with minimal supervision and, most important, with a temporal resolution of less than a minute. For this purpose a microporous hydrophobic membrane contactor (Membrana) was combined with an isotope laser spectrometer (Picarro). The contactor, originally designed for degassing liquids, was used with N2 as a carrier gas in order to transform a small fraction of liquid water to water vapor. The generated water vapor was then analyzed continuously by the Picarro analyzer. To prove the membrane's applicability, we determined the specific isotope fractionation factor for the phase change through the contactor's membrane across an extended temperature range (8°C-21°C) and with different waters of known isotopic compositions. This fractionation factor is needed to subsequently derive the liquid water isotope ratio from the measured water vapor isotope ratios. The system was tested with a soil column experiment, where the isotope values derived with the new method corresponded well (R2 = 0.998 for δ18O and R2 = 0.997 for δ2H) with those of liquid water samples taken simultaneously and analyzed with a conventional method (cavity ring-down spectroscopy). The new method supersedes taking liquid samples and employs only relatively cheap and readily available components. This makes it a relatively inexpensive, fast, user-friendly, and easily reproducible method. It can be applied in both the field and laboratory wherever a water vapor isotope analyzer can be run and whenever real-time isotope data of liquid water are required at high temporal resolution.

  3. Metal Stable Isotope Tagging: Renaissance of Radioimmunoassay for Multiplex and Absolute Quantification of Biomolecules. (United States)

    Liu, Rui; Zhang, Shixi; Wei, Chao; Xing, Zhi; Zhang, Sichun; Zhang, Xinrong


    The unambiguous quantification of biomolecules is of great significance in fundamental biological research as well as practical clinical diagnosis. Due to the lack of a detectable moiety, the direct and highly sensitive quantification of biomolecules is often a "mission impossible". Consequently, tagging strategies to introduce detectable moieties for labeling target biomolecules were invented, which had a long and significant impact on studies of biomolecules in the past decades. For instance, immunoassays have been developed with radioisotope tagging by Yalow and Berson in the late 1950s. The later languishment of this technology can be almost exclusively ascribed to the use of radioactive isotopes, which led to the development of nonradioactive tagging strategy-based assays such as enzyme-linked immunosorbent assay, fluorescent immunoassay, and chemiluminescent and electrochemiluminescent immunoassay. Despite great success, these strategies suffered from drawbacks such as limited spectral window capacity for multiplex detection and inability to provide absolute quantification of biomolecules. After recalling the sequences of tagging strategies, an apparent question is why not use stable isotopes from the start? A reasonable explanation is the lack of reliable means for accurate and precise quantification of stable isotopes at that time. The situation has changed greatly at present, since several atomic mass spectrometric measures for metal stable isotopes have been developed. Among the newly developed techniques, inductively coupled plasma mass spectrometry is an ideal technique to determine metal stable isotope-tagged biomolecules, for its high sensitivity, wide dynamic linear range, and more importantly multiplex and absolute quantification ability. Since the first published report by our group, metal stable isotope tagging has become a revolutionary technique and gained great success in biomolecule quantification. An exciting research highlight in this area

  4. BASIN TCP Stable Isotope Composition of CO2 in Terrestrial Ecosystems (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports stable isotope ratio data of CO2 (13C/12C and 18O/16O) associated with photosynthetic and respiratory exchanges across the...

  5. Use of stable isotope analysis to determine of the timing of ontogenic habitat shifts (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SAIP funding for stable isotope research was provided in FY11 and FY13; the FY11 funding was for loggerhead turtles (described below) as opposed to green turtles in...

  6. Precipitation and stream water stable isotope data from the Marys River, Oregon in water year 2015. (United States)

    U.S. Environmental Protection Agency — Water stable isotope data collected from a range of streams throughout the Marys River basin in water year 2015, and precipitation data collected within the basin at...

  7. LBA-ECO CD-02 Carbon, Nitrogen, Oxygen Stable Isotopes in Organic Material, Brazil (United States)

    National Aeronautics and Space Administration — This data set reports the measurement of stable carbon, nitrogen, and oxygen isotope ratios in organic material (plant, litter and soil samples) in forest canopy...

  8. LBA-ECO CD-02 Carbon, Nitrogen, Oxygen Stable Isotopes in Organic Material, Brazil (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports the measurement of stable carbon, nitrogen, and oxygen isotope ratios in organic material (plant, litter and soil samples) in forest...

  9. BASIN TCP Stable Isotope Composition of CO2 in Terrestrial Ecosystems (United States)

    National Aeronautics and Space Administration — This data set reports stable isotope ratio data of CO2 (13C/12C and 18O/16O) associated with photosynthetic and respiratory exchanges across the biosphere-atmosphere...

  10. Alaska Northern Fur Seal Foraging Habitat Model Stable Isotope Data, 2006-2008 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data sets were used by Zeppelin et al. (2015) to model northern fur seal foraging habitats based on stable isotope values measured in plasma and red blood...

  11. Stable isotopic analysis of Barnacle larvae and their faecal pellets to evaluate the ingested food

    Digital Repository Service at National Institute of Oceanography (India)

    Gaonkar, C.A.; Anil, A.C.

    Stable isotopes of carbon and nitrogen are useful in the evaluation of food web dynamics and have been used extensively in the feeding studies. Barnacles are dominant component of the intertidal and bio-fouling communities. Life cycle of barnacles...

  12. Stable isotope ratio method for the characterisation of the poultry house environment. (United States)

    Skipitytė, Raminta; Mašalaitė, Agnė; Garbaras, Andrius; Mickienė, Rūta; Ragažinskienė, Ona; Baliukonienė, Violeta; Bakutis, Bronius; Šiugždaitė, Jūratė; Petkevičius, Saulius; Maruška, Audrius Sigitas; Remeikis, Vidmantas


    Stable isotope analysis was applied to describe the poultry house environment. The poultry house indoor environment was selected for this study due to the relevant health problems in animals and their caretakers. Air quality parameters including temperature, relative humidity, airflow rate, NH3, CO2 and total suspended particles, as well as mean levels of total airborne bacteria and fungi count, were measured. Carbon isotope ratios (13C/12C) were obtained in size-segregated aerosol particles. The carbon (13C/12C) and nitrogen (15N/14N) isotope ratios were measured in feed, litter, scrapings from the ventilation system, feathers and eggs. Additionally, the distribution of δ13C and δ15N values in different tissues of the chicken was examined. The airborne bacteria and fungi extracted from the air filters collected from poultry farms were grown in the laboratory in media with known isotope values and measured for stable isotope ratios. Analysis of isotope fractionation between microorganisms and their media indicated the applicability of stable isotope analysis in bulk samples for the identification of source material. The analysed examples imply that stable isotope analysis can be used to examine the indoor environment along with its biology and ecology, and serve as an informative bioanalytical tool.

  13. Stable isotopes dissect aquatic food webs from the top to the bottom

    NARCIS (Netherlands)

    Middelburg, J.J.|info:eu-repo/dai/nl/079665373


    Stable isotopes have been used extensively to study food-web functioning, that is, the flow of energy and matter among organisms. Traditional food-web studies are based on the natural variability of isotopes and are limited to larger organisms that can be physically separated from their environment.

  14. Stable water isotopes suggest sub-canopy water recycling in a northern forested catchment (United States)

    Mark B. Green; Bethany K. Laursen; John L. Campbell; Kevin J. McGuire; Eric P. Kelsey


    Stable water isotopes provide a means of tracing many hydrologic processes, including poorly understood dynamics like soil water interactions with the atmosphere. We present a four-year dataset of biweekly water isotope samples from eight fluxes and stores in a headwater catchment at the Hubbard Brook Experimental Forest, New Hampshire, USA. We use Dansgaard's...

  15. Stable isotopes of soil collected from feet of two species of migratory ...

    African Journals Online (AJOL)

    tween capture date (arrival date) and soil isotopic values (δ13Csoil_feet or δDsoil_feet) was explored using Pearson correlation coefficients and bivariate scatter plots. Stable isotope variables of soils from birds' feet were normally distributed (Kolmogorov-. Smirnov test, p> 0.05). Results. Carbon. The δ13Csoil_feet values ...

  16. Endogenous surfactant metabolism in critically ill infants measured with stable isotope labeled fatty acids

    NARCIS (Netherlands)

    Cogo, PE; Carnielli, VP; Bunt, JEH; Badon, T; Giordano, G; Zacchello, F; Sauer, PJJ; Zimmermann, LJI

    Little is known about endogenous surfactant metabolism in infants, because radioactive isotopes used for this purpose in animals cannot be used in humans. We developed a novel and safe method to measure the endogenous surfactant kinetics in vivo in humans by using stable isotope labeled fatty acids.

  17. Stable isotope sales: Mound Facility customer and shipment summaries, FY 1981

    Energy Technology Data Exchange (ETDEWEB)

    Ruwe, Jr, A H [comp.


    A listing is given of Mound Facility's sales of stable isotopes of noble gases, carbon, oxygen, nitrogen, chlorine, and sulfur for Fiscal Year 1981. Purchasers are listed alphabetically and are divided into domestic and foreign groups. A cross-reference index by location is included for domestic customers. Cross-reference listings by isotope purchased are included for all customers.

  18. Improved constraints on in situ rates and on quantification of complete chloroethene degradation from stable carbon isotope mass balances in groundwater plumes (United States)

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


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

  19. Stable isotope separation in calutrons: Forty years of production and distribution

    Energy Technology Data Exchange (ETDEWEB)

    Bell, W.A.; Tracy, J.G.


    The stable isotope separation program, established in 1945, has operated continually to provide enriched stable isotopes and selected radioactive isotopes, including the actinides, for use in research, medicine, and industrial applications. This report summarizes the first forty years of effort in the production and distribution of stable isotopes. Evolution of the program along with the research and development, chemical processing, and production efforts are highlighted. A total of 3.86 million separator hours has been utilized to separate 235 isotopes of 56 elements. Relative effort expended toward processing each of these elements is shown. Collection rates (mg/separator h), which vary by a factor of 20,000 from the highest to the lowest (/sup 205/Tl to /sup 46/Ca), and the attainable isotopic purity for each isotope are presented. Policies related to isotope pricing, isotope distribution, and support for the enrichment program are discussed. Changes in government funding, coupled with large variations in sales revenue, have resulted in 7-fold perturbations in production levels.

  20. Human neutrophil kinetics: modeling of stable isotope labeling data supports short blood neutrophil half-lives


    Lahoz-Beneytez, J; Elemans, M; Zhang, Y.; R. Ahmed; Salam, A.; Block, M.; Niederalt, C; Asquith, B; Macallan, D


    Human neutrophils have traditionally been thought to have a short half-life in blood; estimates vary from 4-18 hours. This dogma was recently challenged by stable isotope labeling studies with heavy water which yielded estimates in excess of 3 days. To investigate this disparity we generated new stable isotope labeling data in healthy adult subjects using both heavy water (n=4) and deuterium-labeled glucose (n=9), a compound with more rapid labeling kinetics. To interpret results we developed...

  1. Antarctic Holocene climate change: A benthic foraminiferal stable isotope record from Palmer Deep


    Shevenell, A. E.; Kennett, J. P.


    The first moderate- to high-resolution Holocene marine stable isotope record from the nearshore Antarctic continental shelf (Ocean Drilling Program (ODP) Hole 1098B) suggests sensitivity of the western Antarctic Peninsula hydrography to westerly wind strength and El Nino-Southern Oscillation (ENSO)-like climate variability. Despite proximity to corrosive Antarctic water masses, sufficient CaCO3 in Palmer Deep sediments exists to provide a high-quality stable isotopic record (especially in the...

  2. Stable isotope characteristics of precipitation of Pamba River basin ...

    Indian Academy of Sciences (India)

    Altitude effect was evident for the basin (0.1‰ for δ 18 O and 0.8‰ for δ 2 δ2H per 100 m elevation), while the amount effect was weak. The precipitation formed from the marine moisture supplied at a steady rate, without much isotopic evolution in this period may have masked the possible depletion of heavier isotopes with ...

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

    KAUST Repository

    Cai, Mick Y.


    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

  4. Titanium stable isotopic variations in chondrites, achondrites and lunar rocks (United States)

    Greber, Nicolas D.; Dauphas, Nicolas; Puchtel, Igor S.; Hofmann, Beda A.; Arndt, Nicholas T.


    Titanium isotopes are potential tracers of processes of evaporation/condensation in the solar nebula and magmatic differentiation in planetary bodies. To gain new insights into the processes that control Ti isotopic variations in planetary materials, 25 komatiites, 15 chondrites, 11 HED-clan meteorites, 5 angrites, 6 aubrites, a martian shergottite, and a KREEP-rich impact melt breccia have been analyzed for their mass-dependent Ti isotopic compositions, presented using the δ49Ti notation (deviation in permil of the 49Ti/47Ti ratio relative to the OL-Ti standard). No significant variation in δ49Ti is found among ordinary, enstatite, and carbonaceous chondrites, and the average chondritic δ49Ti value of +0.004 ± 0.010‰ is in excellent agreement with the published estimate for the bulk silicate Earth, the Moon, Mars, and the HED and angrite parent-bodies. The average δ49Ti value of komatiites of -0.001 ± 0.019‰ is also identical to that of the bulk silicate Earth and chondrites. OL-Ti has a Ti isotopic composition that is indistinguishable from chondrites and is therefore a suitable material for reporting δ49Ti values. Previously published isotope data on another highly refractory element, Ca, show measurable variations among chondrites. The decoupling between Ca and Ti isotope systematics most likely occurred during condensation in the solar nebula. Aubrites exhibit significant variations in δ49Ti, from -0.07 to +0.24‰. This is likely due to the uniquely reducing conditions under which the aubrite parent-body differentiated, allowing chalcophile Ti3+ and lithophile Ti4+ to co-exist. Consequently, the observed negative correlation between δ49Ti values and MgO concentrations among aubrites is interpreted to be the result of isotope fractionation driven by the different oxidation states of Ti in this environment, such that isotopically heavy Ti4+ was concentrated in the residual liquid during magmatic differentiation. Finally, KREEPy impact melt breccia

  5. Stable isotope characterization of milk components and whey ethanol. (United States)

    Masud, Z; Vallet, C; Martin, G J


    A multi-isotopic study of several components of milk has been carried out on commercial samples and on milk produced in feeding experiments involving different kinds of diets originating from C(3) or C(4) photosynthetic metabolisms and exhibiting a relatively wide range of isotope ratios. The dispersion of the carbon, hydrogen, and nitrogen isotope parameters of dried matter and of the lactose, protein, and lipid components has been estimated. In addition, the carbohydrates were represented by the site specific isotope ratios (SNIF-NMR) of ethanol resulting from standardized fermentation of lactose. The rates of response of the isotopic parameters to changes in the feeding materials is slower for the minor components, proteins, and lipids than for lactose and ethanol. For similar diets, the nonexchangeable sites of lactose and the methyl site of ethanol, in particular, are relatively enriched in deuterium in the case of polygastric animals, cow, goat, and ewe, as compared to the monogastric species, sow and mare, and woman. From an analytical point of view, the carbon and hydrogen parameters of ethanol provide efficient criteria for identifying a whey origin with respect to other agricultural and fossil sources.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  7. Dietary interpretations for extinct megafauna using coprolites, intestinal contents and stable isotopes: Complimentary or contradictory? (United States)

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


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

  8. Stable isotope composition and volume of Early Archaean oceans

    DEFF Research Database (Denmark)

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

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

  9. Stable carbon isotope fractionation by sulfate-reducing bacteria (United States)

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


    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.

  10. Classification of Chinese Honeys According to Their Floral Origins Using Elemental and Stable Isotopic Compositions. (United States)

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


    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.

  11. Modeling of present and Eemian stable water isotopes in precipitation

    DEFF Research Database (Denmark)

    Sjolte, Jesper

    The subject of this thesis is the modeling of the isotopic temperature proxies d18O, dD and deuterium excess in precipitation. Two modeling studies were carried out, one using the regional climate model, and one using a global climate model. In the regional study the model was run for the period...... the modeled isotopes do not agree with ice core data. The discrepancy between the model output and the ice core data is attributed to the boundary conditions, where changes in ice sheets and vegetation have not been accounted for....

  12. Equations for lipid normalization of carbon stable isotope ratios in aquatic bird eggs.

    Directory of Open Access Journals (Sweden)

    Kyle H Elliott

    Full Text Available 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.

  13. Historical and contemporary stable isotope tracer approaches to studying mammalian protein metabolism (United States)


    Over a century ago, Frederick Soddy provided the first evidence for the existence of isotopes; elements that occupy the same position in the periodic table are essentially chemically identical but differ in mass due to a different number of neutrons within the atomic nucleus. Allied to the discovery of isotopes was the development of some of the first forms of mass spectrometers, driven forward by the Nobel laureates JJ Thomson and FW Aston, enabling the accurate separation, identification, and quantification of the relative abundance of these isotopes. As a result, within a few years, the number of known isotopes both stable and radioactive had greatly increased and there are now over 300 stable or radioisotopes presently known. Unknown at the time, however, was the potential utility of these isotopes within biological disciplines, it was soon discovered that these stable isotopes, particularly those of carbon (13C), nitrogen (15N), oxygen (18O), and hydrogen (2H) could be chemically introduced into organic compounds, such as fatty acids, amino acids, and sugars, and used to “trace” the metabolic fate of these compounds within biological systems. From this important breakthrough, the age of the isotope tracer was born. Over the following 80 yrs, stable isotopes would become a vital tool in not only the biological sciences, but also areas as diverse as forensics, geology, and art. This progress has been almost exclusively driven through the development of new and innovative mass spectrometry equipment from IRMS to GC‐MS to LC‐MS, which has allowed for the accurate quantitation of isotopic abundance within samples of complex matrices. This historical review details the development of stable isotope tracers as metabolic tools, with particular reference to their use in monitoring protein metabolism, highlighting the unique array of tools that are now available for the investigation of protein metabolism in vivo at a whole body down to a single protein level

  14. Stable isotope characteristics of precipitation of Pamba River basin ...

    Indian Academy of Sciences (India)

    Isotope Hydrology Division, Centre for Water Resources Development and Management, .... 5.9% by fallow lands. 2.1 Climate. The Pamba River basin experiences ∼3000 mm of rainfall per year. The south-west and north- east monsoons have great influence over the cli- ..... precipitation per 100 m of elevation change.

  15. Gas cleaning with hot char beds studied by stable isotopes

    DEFF Research Database (Denmark)

    Egsgaard, Helge; Ahrenfeldt, Jesper; Ambus, Per


    The chemistry taking place in a high temperature char bed used for binding aromatic tar compounds has been studied in detail. 13C labelled tar compounds were used to trace the incorporation into the char bed using isotope ratio mass spectrometry (IRMS) and GC-MS. Furthermore, compounds labelled...

  16. Fractionation of Stable Isotopes in Atmospheric Aerosol Reactions

    DEFF Research Database (Denmark)

    Meusinger, Carl

    as required. The kndings provide important results for the studies' respective felds, including a description of the isotopic fractionation and quantum yield of nitrate photolysis in snow, equilibrium fractionation in secondary organic aerosol and fractionation constants of different oxidation pathways of SO2....

  17. Chromium stable isotope fractionation in modern biogeochemical cycling

    DEFF Research Database (Denmark)

    Paulukat, Cora Stefanie

    Chromium (Cr) is, due to its redox-sensitive properties, a powerful tracer for redox processes in environmental studies. Changes in its preferred oxidation state (III and VI) are accompanied by Crisotope fractionation. The Cr-isotope system is a promising tool to reconstruct the evolution of free...

  18. Simulating Stable Isotope Ratios in Plumes of Groundwater Pollutants with BIOSCREEN-AT-ISO. (United States)

    Höhener, Patrick; Li, Zhi M; Julien, Maxime; Nun, Pierrick; Robins, Richard J; Remaud, Gérald S


    BIOSCREEN is a well-known simple tool for evaluating the transport of dissolved contaminants in groundwater, ideal for rapid screening and teaching. This work extends the BIOSCREEN model for the calculation of stable isotope ratios in contaminants. A three-dimensional exact solution of the reactive transport from a patch source, accounting for fractionation by first-order decay and/or sorption, is used. The results match those from a previously published isotope model but are much simpler to obtain. Two different isotopes may be computed, and dual isotope plots can be viewed. The dual isotope assessment is a rapidly emerging new approach for identifying process mechanisms in aquifers. Furthermore, deviations of isotope ratios at specific reactive positions with respect to "bulk" ratios in the whole compound can be simulated. This model is named BIOSCREEN-AT-ISO and will be downloadable from the journal homepage. © 2016, National Ground Water Association.

  19. Advantages of using fecal samples for stable isotope analysis in bats: evidence from a triple isotopic experiment. (United States)

    Salvarina, Ioanna; Yohannes, Elizabeth; Siemers, Björn M; Koselj, Klemen


    Stable isotope analysis in ecological studies is usually conducted on biomaterials, e.g. muscle and blood, that require catching the animals. Feces are rarely used for stable isotope analysis, despite the possibility of non-invasive sampling and short-term responsiveness to dietary changes. This promising method is neglected due to a lack of calibration experiments and unknown diet-feces isotopic difference (Δ(diet-feces)). To fill this gap, we simulated trophic changes occurring in nature when animals switch feeding habitats, e.g. by moving from freshwater to terrestrial systems, from cultivated areas to forests or changing distance from marine environments. In a controlled experiment, the diet of two bat species (Myotis myotis, Rhinolophus ferrumequinum) was altered to an isotopically distinct one. We measured stable nitrogen, carbon and the rarely used sulfur isotope in feces, and calculated Δ(diet-feces) values. The feces acquired the new dietary signature within 2-3 h from food ingestion; thus, they are suited for detecting recent and rapid dietary changes. The Δ(diet-feces) (Δ) did not differ between species or diet (overall means ± standard deviation (sd)): Δ(15)N: 1.47 ± 1.51‰, Δ(13)C: -0.11 ± 0.80‰, Δ(34)S: 0.74 ± 1.10‰. Only Δ(15)N for M. myotis was significantly different from zero and only Δ(13) C differed among the days of the experiment. Fecal stable isotopes can be now further applied in mammalian ecology. This includes a range of applications, such as studying changes in trophic level, resource or habitat use, on a short time-scale. Such information is gaining importance for monitoring rapidly changing ecosystems under anthropogenic influence. Copyright © 2013 John Wiley & Sons, Ltd.

  20. Turnover of Stable Isotopes Due to Growth and Metabolism in Zebrafish, Danio Rerio (United States)

    Tarboush, R.; MacAvoy, S.; Macko, S.; Connaughton, V.


    Stable isotope ratios of carbon (13C/12C), nitrogen (15 N/14N) and sulfur (34S/32S) in animal tissues can be used as tracers of the nutrient sources of organisms' diets and determining trophic interactions in ecosystems. The isotopic turnover of these elements in a predator's tissues reflects the isotopic signature of the predator's diet (the prey). The rate at which an organism takes up the isotopic signature of its food is correlated with its growth rate and/or metabolism. Hence unless baseline isotopic turnover rates are known, the isotopic signature of a consumer may lead to misinterpretation of predator-prey relationships. Laboratory studies provide isotopic turnover rates of organisms under controlled conditions, which serve as models for understanding the rates at which organisms in the field isotopically incorporate new diets. This study examines the isotopic turnover rates of carbon, nitrogen and sulfur in response to a dietary switch in young zebrafish, Danio rerio. Zebrafish, raised on commercial fish food (8.2 ñ 0.5%, d34S; were fed a new, isotopically distinct diet (2.9 ñ 0.5%, d34S) and the rate at which zebra fish muscle tissues changed towards the isotopic signature of their new food was monitored. Preliminary results show a change in the fish sulfur isotope composition of roughly 0.03% per day towards the sulfur isotope ratio of the new food. At the observed turnover rate, approximately 180 days would be required for the zebrafish muscle tissue to resemble a new food. The study is also investigating the importance of growth versus metabolism as a predictor of isotope turnover rate in zebra fish tissues.

  1. Stable isotopes in collagen and Late Quaternary carnivore palaeoecology (United States)

    Bocherens, Hervé


    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

  2. A manual for a Laboratory Information Management System (LIMS) for light stable isotopes (United States)

    Coplen, Tyler B.


    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.

  3. Quantification of Labile Soil Mercury by Stable Isotope Dilution Techniques (United States)

    Shetaya, Waleed; Huang, Jen-How; Osterwalder, Stefan; Alewell, Christine


    Mercury (Hg) is a toxic element that can cause severe health problems to humans. Mercury is emitted to the atmosphere from both natural and anthropogenic sources and can be transported over long distances before it is deposited to aquatic and terrestrial environments. Aside from accumulation in soil solid phases, Hg deposited in soils may migrate to surface- and ground-water or enter the food chain, depending on its lability. There are many operationally-defined extraction methods proposed to quantify soil labile metals. However, these methods are by definition prone to inaccuracies such as non-selectivity, underestimation or overestimation of the labile metal pool. The isotopic dilution technique (ID) is currently the most promising method for discrimination between labile and non-labile metal fractions in soil with a minimum disturbance to soil-solid phases. ID assesses the reactive metal pool in soil by defining the fraction of metal both in solid and solution phases that is isotopically-exchangeable known as the 'E-value'. The 'E-value' represents the metal fraction in a dynamic equilibrium with the solution phase and is potentially accessible to plants. This is carried out by addition of an enriched metal isotope to soil suspensions and quantifying the fraction of metal that is able to freely exchange with the added isotope by measuring the equilibrium isotopic ratio by ICP-MS. E-value (mg kg-1) is then calculated as follows: E-Value = (Msoil/ W) (CspikeVspike/ Mspike) (Iso1IAspike -Iso2IAspikeRss / Iso2IAsoil Rss - Iso1IAsoil) where M is the average atomic mass of the metal in the soil or the spike, W is the mass of soil (kg), Cspike is the concentration of the metal in the spike (mg L-1), Vspike is the volume of spike (L), IA is isotopic abundance, and Rss is the equilibrium ratio of isotopic abundances (Iso1:Iso2). Isotopic dilution has been successfully applied to determine E-values for several elements. However, to our knowledge, this method has not yet

  4. Using Stable Isotopes to Trace Microbial Hydrogen Production Pathways (United States)

    Moran, J.; Hill, E.; Bartholomew, R.; Yang, H.; Shi, L.; Ostrom, N. E.; Gandhi, H.; Hegg, E.; Kreuzer, H.


    Biological H2 production by hydrogenase enzymes (H2ases) plays an important role in anaerobic microbial metabolism and community structure. Despite considerable progress in elucidating H2 metabolism, the regulation of and flux through key H2 production pathways remain largely undefined. Our goal is to improve understanding of biological H2 production by using H isotope ratios to dissect proton fluxes through different H2ase enzymes and from different substrates. We hypothesized that the isotope ratio of H2 produced by various hydrogenases (H2ase) would differ, and that the H isotope ratios would allow us to define the contribution of different enzymes when more than one is present in vivo. We chose Shewanella oneidensis (S.o.) MR-1, a facultative anaerobe capable of transferring electrons to a variety of terminal acceptors, including protons, as a model system for in vivo studies. S. o. encodes one [FeFe]- and one [NiFe]-H2ase. We purified three [FeFe]-H2ases (S.o., Clostridium pasteurianum, and Chlamydomonas reinhardtii) and two [NiFe]-H2ases (S. o. and Desulfovibrio fructosovorans) to test the isotope fractionation associated with activity by each enzyme in vitro. For in vivo analysis we used wild-type S.o. as well as electron transfer-deficient and H2ase-deficient strains. We employed batch cultures using lactate as an electron donor and O2 as an initial electron acceptor (with H2 production after O2 consumption). The five H2ases we tested all had a unique isotope fractionation. Measurements of H2 produced in vivo showed distinct periods of H2 production having isotope signatures consistent with in vitro results. Isotope data as well as studies of H2 production by mutants in the genes encoding either the [NiFe]-H2ase or the [FeFe]-H2ase, respectively, show that the [NiFe]- and [FeFe]- H2ases became active at different times. The [NiFe]-H2ase both produces and consumes H2 before the [FeFe]-H2ase becomes active. RNA analysis is consistent with up regulation of

  5. Production and use of stable isotope-labeled proteins for absolute quantitative proteomics. (United States)

    Lebert, Dorothée; Dupuis, Alain; Garin, Jérôme; Bruley, Christophe; Brun, Virginie


    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.

  6. Discrimination factors of carbon and nitrogen stable isotopes in meerkat feces

    Directory of Open Access Journals (Sweden)

    Shaena Montanari


    Full Text Available Stable isotope analysis of feces can provide a non-invasive method for tracking the dietary habits of nearly any mammalian species. While fecal samples are often collected for macroscopic and genetic study, stable isotope analysis can also be applied to expand the knowledge of species-specific dietary ecology. It is somewhat unclear how digestion changes the isotope ratios of animals’ diets, so more controlled diet studies are needed. To date, most diet-to-feces controlled stable isotope experiments have been performed on herbivores, so in this study I analyzed the carbon and nitrogen stable isotope ratios in the diet and feces of the meerkat (Suricata suricatta, a small omnivorous mammal. The carbon trophic discrimination factor between diet and feces (Δ13Cfeces is calculated to be 0.1 ± 1.5‰, which is not significantly different from zero, and in turn, not different than the dietary input. On the other hand, the nitrogen trophic discrimination factor (Δ15Nfeces is 1.5 ± 1.1‰, which is significantly different from zero, meaning it is different than the average dietary input. Based on data generated in this experiment and a review of the published literature, carbon isotopes of feces characterize diet, while nitrogen isotope ratios of feces are consistently higher than dietary inputs, meaning a discrimination factor needs to be taken into account. The carbon and nitrogen stable isotope values of feces are an excellent snapshot of diet that can be used in concert with other analytical methods to better understand ecology, diets, and habitat use of mammals.

  7. Study of the charge radii of the stable lead isotopes

    CERN Document Server

    Borchert, G L; Jonson, B; McGrory, J B; Ravn, H L; Schult, O W B; Speth, J


    Isotope shifts have been measured of the K alpha /sub 1/ 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. (33 refs).

  8. Strontium stable isotope behaviour in foraminiferal calcite and the retrieval of marine records (United States)

    Stevenson, E.; Burton, K.; Rickaby, R.; Parkinson, I. J.; Anand, P.; Hathorne, E.


    The stable strontium (88Sr/86Sr) isotope composition of seawater recorded in sedimentary foraminifera potentially provides key information on variations in the composition of material delivered by continental weathering to the oceans and on changes in carbonate productivity over time. However, recent studies suggest a significant temperature dependent fractionation of Sr stable isotopes during the precipitation of calcium carbonate, which must be quantified before seawater records can be accurately retrieved [1, 2]. This study presents high-precision stable Sr isotope data (±10 ppm 2 s.d.) for core-top planktonic foraminifera from sites in the South Atlantic with a range of annual sea surface temperatures of 18 - 28°C, and preliminary data for quaternary marine foraminiferal records from the SE Indian Ocean. These results indicate that there is no signficiant variation in the stable isotope composition of an individual species across the temperature range studied here, but there are resolvable differences in the offset from seawater between species. In this case, seawater stable Sr isotope records can be reconstructed without the necessity of a temperature correction. The preliminary results for a glacial-interglacial planktonic foraminifera record indicate that there are no resolvable variations in the stable isotope ratios over this time interval, indicating that there are no significant variations in the Sr isotope composition of continental runoff or carbonate productivity in the oceans over this time interval. [1] Fietzke, J., Eisenhauer, A. (2006), Geochem. Geophys. Geosyst., 7, (8), 1-6 . [2] Ruggerburg, A., Fietzke, J., Liebetrau, V. Eisenhauer, A., Dullo, W-C., Freiwald, A. (2008). Earth Plan. Sci. Lett. 269, 570-575

  9. Recent research activities and future subjects on stable- and radio-isotopes of chlorine in environment

    Energy Technology Data Exchange (ETDEWEB)

    Kushita, Kouhei [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    This report reviews the recent studies on the stable- and radio-isotopes of chlorine from a viewpoint of environmental science, partly including historic references on this element. First, general properties, occurrence, and utilization of chlorine are described. Secondly, current status and research works on chlorine-compounds, which attract special attention in recent years as environmentally hazardous materials, are reported. Thirdly, research works on stable chlorine isotopes, {sup 35}Cl and {sup 37}Cl, are described with a focus laid on the newly-developed techniques; isotopic ratio mass spectrometry (IRMS) and thermal ionization mass spectrometry (TIMS). Fourthly, recent research works on chlorine radioisotopes, {sup 36}Cl etc., are described, focusing on the development of accelerator mass spectrometry (AMS) and its application to geochemistry and others. Finally, taking account of the above-mentioned recent works on Cl isotopes, possible future research subjects are discussed. (author)

  10. Stable isotopes in alpine precipitation as tracers of atmospheric deposition (United States)

    Wasiuta, V. L.; Lafreniere, M. J.; Kyser, T. K.; Norman, A. L.; Mayer, B.; Wieser, M.


    Alpine ecosystems, which are generally nutrient poor and exist under extreme climatic conditions, are particularly sensitive to environmental and climatic stressors. Studies in the USA Rocky Mountains and European Alps have shown that alpine terrestrial and aquatic ecosystems are particularly sensitive to enhanced deposition of reactive nitrogen and can show ecologically destructive responses at relatively low levels of nitrogen deposition. However, there is no base line for atmospheric deposition of natural and anthropogenic contaminants in the Canadian alpine. Preliminary results of isotopic and chemical analyses of precipitation from an elevational transect on a glaciated alpine site in the Canadian Rockies are presented. Precipitation accumulating from early autumn through to spring (2008/2009 and 2009/2010) was sampled by means of seasonal snow cover on alpine glaciers. Summer precipitation was sampled through July and August 2010 using bulk collectors installed at the sites of winter sampling. The isotope ratios of dissolved sulphate (δ34S, δ18O), nitrogen (δ15N, δ18O), as well as precipitation (δ2H, δ18O) are utilized in addition to major ion concentrations and trace metal concentrations. Results from 2008/2009 snowpack samples indicate a strong seasonal trend in sulphate (SO42-) and nitrogen (NO3-) deposition which is consistent across the altitudinal transect. Snow horizons representing early autumn and spring precipitation show higher SO42- and NO3- concentrations in contrast to lower concentrations in winter horizons. The aforementioned suite of isotopic and chemical analyses are used to investigate the variability in dominant geographic source regions for atmospheric SO42- and NO3- (local, regional, or long range transported contaminants), as well as to identify contributions from the major biogeochemical source types (e.g. hydrocarbon combustion, lithogenic dust, agricultural emissions).

  11. Evaluation of stable tungsten isotopes in the resolved resonance region

    Directory of Open Access Journals (Sweden)

    Schillebeeckx P.


    Full Text Available In the last decade benchmark experiments and simulations, together with newly obtained neutron cross section data, have pointed out deficiencies in evaluated data files of W isotopes. The role of W as a fundamental structural material in different nuclear applications fully justifies a new evaluation of 182, 183, 184, 186W neutron resonance parameters. In this regard transmission and capture cross section measurements on natural and enriched tungsten samples were performed at the GELINA facility of the EC-JRC-IRMM. A resonance parameter file used as input in the resonance shape analysis was prepared based on the available literature and adjusted in first instance to transmission data.

  12. Stable isotope analysis using tunable diode laser spectroscopy (United States)

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


    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.

  13. Determination of hexavalent chromium reduction using Cr stable isotopes: isotopic fractionation factors for permeable reactive barrier materials. (United States)

    Basu, Anirban; Johnson, Thomas M


    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 ε) 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.

  14. Stable isotope sales: Mound Laboratory customer and shipment summaries, FY 1976 and FY 1976A

    Energy Technology Data Exchange (ETDEWEB)

    Ruwe, A.H. Jr. (comp.)


    A listing is given of Mound Laboratory's sales of stable isotopes of noble gases, carbon, oxygen, nitrogen, chlorine, and sulfur for fiscal years 1976 and 1976A (the period July 1, 1975 through September 30, 1976). Purchasers are listed alphabetically and are divided into domestic and foreign groups. A cross-reference index by location is included for domestic customers. Cross-reference listings by isotope purchased are included for all customers.

  15. Distinguishing feral and managed honeybees (Apis mellifera) using stable carbon isotopes


    Anderson, Lucy; Dynes, Travis; Berry, Jennifer; Delaplane, Keith; McCormick, Lydia; Brosi, Berry


    International audience; The ability to distinguish feral and managed honeybees (Apis mellifera) has applications in studies of population genetics, parasite transmission, pollination, interspecific interactions, and bee breeding. We evaluated a diagnostic test based on theoretical differences in stable carbon isotope ratios generated by supplemental feeding. We evaluated (1) if carbon isotope ratios can distinguish feral and managed honeybees and (2) the temporal persistence of the signal aft...

  16. Migration dynamics of clupeoids in the Schelde estuary: a stable isotope approach

    DEFF Research Database (Denmark)

    Guelinckx, J.; Maes, J.; De Brabandere, Loreto


    using C and N stable isotopes. Prior to this,  stomach contents were used to verify the isotopic differences between the food sources at the sampling stations. From May 2000 to April 2001 fish were collected monthly in the upper and lower estuary. Muscle tissue and stomach contents were analyzed for d13...... is concluded the results support the hypothesis that migration to estuarine nurseries is individually based....

  17. Analytical modelling of stable isotope fractionation of volatile organic compounds in the unsaturated zone

    CERN Document Server

    Bouchard, D; Höhener, P; Hunkeler, D; 10.1016/j.jconhyd.2010.09.006


    Analytical models were developed that simulate stable isotope ratios of volatile organic compounds (VOCs) near a point source contamination in the unsaturated zone. The models describe diffusive transport of VOCs, biodegradation and source ageing. The mass transport is governed by Fick's law for diffusion, and the equation for reactive transport of VOCs in the soil gas phase was solved for different source geometries and for different boundary conditions. Model results were compared to experimental data from a one-dimensional laboratory column and a radial-symmetric field experiment, and the comparison yielded a satisfying agreement. The model results clearly illustrate the significant isotope fractionation by gas-phase diffusion under transient state conditions. This leads to an initial depletion of heavy isotopes with increasing distance from the source. The isotope evolution of the source is governed by the combined effects of isotope fractionation due to vaporization, diffusion and biodegradation. The net...

  18. Stable iron isotope fractionation between aqueous Fe(II) and hydrous ferric oxide. (United States)

    Wu, Lingling; Beard, Brian L; Roden, Eric E; Johnson, Clark M


    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 (2σ)‰ and -2.58 ± 0.14 (2σ)‰ 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.

  19. A stable isotope approach and its application for identifying nitrate source and transformation process in water. (United States)

    Xu, Shiguo; Kang, Pingping; Sun, Ya


    Nitrate contamination of water is a worldwide environmental problem. Recent studies have demonstrated that the nitrogen (N) and oxygen (O) isotopes of nitrate (NO3(-)) can be used to trace nitrogen dynamics including identifying nitrate sources and nitrogen transformation processes. This paper analyzes the current state of identifying nitrate sources and nitrogen transformation processes using N and O isotopes of nitrate. With regard to nitrate sources, δ(15)N-NO3(-) and δ(18)O-NO3(-) values typically vary between sources, allowing the sources to be isotopically fingerprinted. δ(15)N-NO3(-) is often effective at tracing NO(-)3 sources from areas with different land use. δ(18)O-NO3(-) is more useful to identify NO3(-) from atmospheric sources. Isotopic data can be combined with statistical mixing models to quantify the relative contributions of NO3(-) from multiple delineated sources. With regard to N transformation processes, N and O isotopes of nitrate can be used to decipher the degree of nitrogen transformation by such processes as nitrification, assimilation, and denitrification. In some cases, however, isotopic fractionation may alter the isotopic fingerprint associated with the delineated NO3(-) source(s). This problem may be addressed by combining the N and O isotopic data with other types of, including the concentration of selected conservative elements, e.g., chloride (Cl(-)), boron isotope (δ(11)B), and sulfur isotope (δ(35)S) data. Future studies should focus on improving stable isotope mixing models and furthering our understanding of isotopic fractionation by conducting laboratory and field experiments in different environments.

  20. Beyond diet reconstruction: stable isotope applications to human physiology, health, and nutrition. (United States)

    Reitsema, Laurie J


    Analysis of stable carbon and nitrogen isotopes from soft or mineralized tissues is a direct and widely-used technique for modeling diets. In addition to its continued role in paleodiet analysis, stable isotope analysis is now contributing to studies of physiology, disease, and nutrition in archaeological and living human populations. In humans and other animals, dietary uptake and distribution of carbon and nitrogen among mineralized and soft tissue is carried out with varying efficiency due to factors of internal biology. Human pathophysiologies may lead to pathology-influenced isotopic fractionation that can be exploited to understand not just skeletal health and diet, but physiological health and nutrition. This study reviews examples from human biology, non-human animal ecology, biomedicine, and bioarchaeology demonstrating how stable isotope analyses are usefully applied to the study of physiological adaptation and adaptability. Suggestions are made for future directions in applying stable isotope analysis to the study of nutritional stress, disease, and growth and development in living and past human populations. Copyright © 2013 Wiley Periodicals, Inc.

  1. Stable carbon isotope fractionation as tracer of carbon cycling in anoxic soil ecosystems. (United States)

    Blaser, Martin; Conrad, Ralf


    While the structure of microbial communities can nowadays be determined by applying molecular analytical tools to soil samples, microbial function can usually only be determined by physiological experiments requiring incubation of samples. However, analysis of stable isotope fractionation might be able to analyse microbial function without incubation in soil samples. We describe the limitations of diagnosing and quantifying carbon flux pathways in soil by using the determination of stable carbon isotope composition in soil compounds and emphasize the importance of determining stable isotope fractionation factors for defined biochemical pathways. Fractionation factors are sufficiently different for some central biochemical pathways in anaerobic degradation of organic carbon. Thus, it is possible to quantify the relative contribution of CH4 production by hydrogenotrophic or aceticlastic methanogenic pathways, and of acetate formation by chemolithotrophic (acetyl-CoA synthase) or heterotrophic (fermentation) pathways. In addition, stable isotope analysis may allow the differentiation between different organic substrates used for degradation, for example, the relative contribution of root exudation versus soil organic matter degradation, provided the different substrates are sufficiently distinct in their isotopic compositions (e.g., mixture of C3 and C4 plants) and the carbon conversion pathways display only small fractionation factors or are identical for the different substrates. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Use of stable isotopes to monitor the natural attenuation of dicyclopentadiene

    Energy Technology Data Exchange (ETDEWEB)

    Stehemier, L.G.; Cooke, L.; Hornett, R. [Nova Chemicals Ltd., Calgary, AB (Canada); Aravena, R. [Waterloo Univ., ON (Canada)


    Stable isotope fractionation is a method used to prove that residual hydrocarbons from an oil spill are being naturally attenuated in soil and groundwater. Hydrogen isotopes and carbon isotopes are the two isotopes that have been used to provide this evidence. Evaporation, adsorption and biodegradation are among the processes that can cause fractionation of isotopes. However, the largest fractionations take place during biodegradation because of the unidirectional characteristics of metabolism and the thermodynamic selectivity of enzymatic processes in biological systems. This paper presents the results of a monitored natural attenuation program for hydrocarbons in soil and groundwater at a chemical plant in Alberta where dicyclopentadiene (DCPD) was biodegraded. DCPD is a co-product from the cracking of ethane to ethylene. Piezometers were used to monitor the stable isotope fractionation of DCPD over a three year period. Evidence that DCPD was biodegrading was the fact that the change in carbon 13 was enriched 4.1 per cent in one study area during the monitoring period. The results are among the first definitive proof that DCPD biodegrades in the field. Analysis by gas chromatography-carbon-isotope ratio mass spectrometry is an essential technique for monitoring recalcitrant, low water-soluble hydrocarbons. 16 refs., 4 tabs., 3 figs.

  3. Advances in primate stable isotope ecology-Achievements and future prospects. (United States)

    Crowley, Brooke E; Reitsema, Laurie J; Oelze, Vicky M; Sponheimer, Matt


    Stable isotope biogeochemistry has been used to investigate foraging ecology in non-human primates for nearly 30 years. Whereas early studies focused on diet, more recently, isotopic analysis has been used to address a diversity of ecological questions ranging from niche partitioning to nutritional status to variability in life history traits. With this increasing array of applications, stable isotope analysis stands to make major contributions to our understanding of primate behavior and biology. Most notably, isotopic data provide novel insights into primate feeding behaviors that may not otherwise be detectable. This special issue brings together some of the recent advances in this relatively new field. In this introduction to the special issue, we review the state of isotopic applications in primatology and its origins and describe some developing methodological issues, including techniques for analyzing different tissue types, statistical approaches, and isotopic baselines. We then discuss the future directions we envision for the field of primate isotope ecology. Am. J. Primatol. 78:995-1003, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  4. Stable isotope evolution and paleolimnology of ancient Lake Creede (United States)

    Rye, Robert O.; Bethke, Philip M.; Finkelstein, David B.


    The lacustrine carbonate and travertine (tufa) deposits of ancient Lake Creede preserve a remarkable record of the isotopic evolution of the lake. That record indicates that the δ18O of the lake water, and by analogy its salinity, evolved through evaporation. Limited and less reliable data on hydrous minerals and fluid inclusions in early diagenetic carbonates indicate that the δD of the lake waters also evolved through evaporation. The isotope data place restrictions on models of the physical limnology of the lake and its evolution.The closed-basin Lake Creede formed shortly after collapse of the 26.9 Ma Creede caldera. Throughout most of its history it occupied the northern three quarters of the moat between the resurgent dome and wall of the caldera. The Creede Formation was deposited in the basin, dominantly as lacustrine sediments. Travertine mounds interfinger with Creede Formation sediments along the inner and outer margins of the lake basin. An estimated one-half of the original thickness of the Creede Formation has been lost mainly to erosion although scattered remnants of the upper portion remain on the caldera walls. Two diamond core holes (CCM-1 and CCM-2) sampled the uneroded portion of the Creede Formation as part of the U.S. Continental Drilling Program. Volcaniclastic material, including tuff units deposited directly into the lake and ash washed in from the watershed, compose the main lithologies of the Creede Formation. These volcaniclastic strata were produced by episodic ring-fracture volcanism.Lacustrine carbonates make up about 15% of the section sampled by drill core. They occur as 1 mm to 2 cm low-Mg calcite laminae alternating with siliciclastic laminae in scattered intervals throughout the preserved section. The carbonate laminae are accumulations of 5–20 µm crystallites (microsparites) and brine shrimp fecal pellets (peloids) composed mainly of microsparite particles. Low-Mg calcite also occurs as an early diagenetic replacement of

  5. Spectral analysis software improves confidence in plant and soil water stable isotope analyses performed by isotope ratio infrared spectroscopy (IRIS). (United States)

    West, A G; Goldsmith, G R; Matimati, I; Dawson, T E


    Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isotope analysis. Here we report two independent tests of this post-processing spectral analysis software on two IRIS systems, OA-ICOS (Los Gatos Research Inc.) and WS-CRDS (Picarro Inc.). Following a similar methodology to a previous study, we cryogenically extracted plant leaf water and soil water and measured the δ(2)H and δ(18)O values of identical samples by isotope ratio mass spectrometry (IRMS) and IRIS. As an additional test, we analyzed plant stem waters and tap waters by IRMS and IRIS in an independent laboratory. For all tests we assumed that the IRMS value represented the "true" value against which we could compare the stable isotope results from the IRIS methods. Samples showing significant deviations from the IRMS value (>2σ) were considered to be contaminated and representative of spectral interference in the IRIS measurement. Over the two studies, 83% of plant species were considered contaminated on OA-ICOS and 58% on WS-CRDS. Post-analysis, spectra were analyzed using the manufacturer's spectral analysis software, in order to see if the software correctly identified contaminated samples. In our tests the software performed well, identifying all the samples with major errors. However, some false negatives indicate that user evaluation and testing of the software are necessary. Repeat sampling of plants showed considerable variation in the discrepancies between IRIS and IRMS. As such, we recommend that spectral analysis of IRIS data must be incorporated into standard post-processing routines. Furthermore, we suggest that the results from spectral analysis be

  6. Characterization of bile acid metabolism in man using bile acids labeled with stable isotopes. [/sup 13/C

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, A.F. Klein, P.D.


    Bile acids labeled with stable isotopes in the steroid moiety can be used to characterize bile acid metabolism in man. Isotope dilution studies give information on pool size and input. Biotransformations are easily characterized. Stable isotopically labeled bile acids offer the advantage of freedom from radiation hazard, and also offer the possibility of monitoring all pools simultaneously, since all bile acids are separated by gas chromatography before isotope measurements are made. Further, since the proportion of the pool labeled with stable isotopes is greater than that achieved when radioactive isotopes are used, stable isotopes may permit isotope dilution studies to be done on serum samples in which the absolute concentration of bile acids is very low. A major disadvantage is the complex technology required for stable isotope measurement which often makes remote processing necessary. Bile acid labeled with /sup 13/C in the amino acid moiety, e.g. cholylglycine-1-/sup 13/C can be used for detection of increased bile acid deconjugation by intestinal bacteria, since the glycine-/sup 13/C, when liberated, is rapidly converted to /sup 13/CO/sub 2/, which is expired in breath. Bile acids labeled with stable isotopes may also be used for quantitation by inverse isotope dilution, but the technique is still in the development stage and seems unlikely to compete successfully with radioimmunoassay.

  7. Disentangling drought-induced variation in ecosystem and soil respiration using stable carbon isotopes. (United States)

    Unger, Stephan; Máguas, Cristina; Pereira, João S; Aires, Luis M; David, Teresa S; Werner, Christiane


    Combining C flux measurements with information on their isotopic composition can yield a process-based understanding of ecosystem C dynamics. We studied the variations in both respiratory fluxes and their stable C isotopic compositions (delta(13)C) for all major components (trees, understory, roots and soil microorganisms) in a Mediterranean oak savannah during a period with increasing drought. We found large drought-induced and diurnal dynamics in isotopic compositions of soil, root and foliage respiration (delta(13)C(res)). Soil respiration was the largest contributor to ecosystem respiration (R (eco)), exhibiting a depleted isotopic signature and no marked variations with increasing drought, similar to ecosystem respired delta(13)CO(2), providing evidence for a stable C-source and minor influence of recent photosynthate from plants. Short-term and diurnal variations in delta(13)C(res) of foliage and roots (up to 8 and 4 per thousand, respectively) were in agreement with: (1) recent hypotheses on post-photosynthetic fractionation processes, (2) substrate changes with decreasing assimilation rates in combination with increased respiratory demand, and (3) decreased phosphoenolpyruvate carboxylase activity in drying roots, while altered photosynthetic discrimination was not responsible for the observed changes in delta(13)C(res). We applied a flux-based and an isotopic flux-based mass balance, yielding good agreement at the soil scale, while the isotopic mass balance at the ecosystem scale was not conserved. This was mainly caused by uncertainties in Keeling plot intercepts at the ecosystem scale due to small CO(2) gradients and large differences in delta(13)C(res) of the different component fluxes. Overall, stable isotopes provided valuable new insights into the drought-related variations of ecosystem C dynamics, encouraging future studies but also highlighting the need of improved methodology to disentangle short-term dynamics of isotopic composition of R (eco).

  8. Coupling of a headspace autosampler with a programmed temperature vaporizer for stable carbon and hydrogen isotope analysis of volatile organic compounds at microgram per liter concentrations. (United States)

    Herrero-Martín, Sara; Nijenhuis, Ivonne; Richnow, Hans H; Gehre, Matthias


    One major challenge for the environmental application of compound-specific stable isotope analysis (CSIA) is the necessity of efficient sample treatment methods, allowing isolation of a sufficient mass of organic contaminants needed for accurate measurement of the isotope ratios. Here, we present a novel preconcentration technique--the coupling of a headspace (HS) autosampler with a programmed temperature vaporizer (PTV)--for carbon (δ(13)C) and hydrogen (δ(2)H) isotope analysis of volatile organic compounds in water at concentrations of tens of micrograms per liter. The technique permits large-volume injection of headspace samples, maintaining the principle of simple static HS extraction. We developed the method for multielement isotope analysis (δ(13)C and δ(2)H) of methyl tert-butyl ether (MTBE), benzene, toluene, ethylbenzene, and o-xylene (BTEX), and analysis of δ(13)C for chlorinated benzenes and ethenes. Extraction and injection conditions were optimized for maximum sensitivity and minimum isotope effects. Injection of up to 5 mL of headspace sample from a 20 mL vial containing 13 mL of aqueous solution and 5 g of NaCl (10 min of incubation at 90 °C) resulted in accurate δ(13)C and δ(2)H values. The method detection limits (MDLs) for δ(13)C were from 2 to 60 μg/L (MTBE, BTEX, chlorinated ethenes, and benzenes) and 60-97 μg/L for δ(2)H (MTBE and BTEX). Overall, the HS-PTV technique is faster, simpler, isotope effect-free, and requires fewer treatment steps and less sample volume than other extraction techniques used for CSIA. The environmental applicability was proved by the analysis of groundwater samples containing BTEX and chlorinated contaminants at microgram per liter concentrations.

  9. Isolation and stable nitrogen isotope analysis of ammonium ions in ammonium nitrate prills using sodium tetraphenylborate. (United States)

    Howa, John D; Lott, Michael J; Ehleringer, James R


    Because of the threat of bombings using improvised explosives containing ammonium nitrate (AN), law enforcement and intelligence communities have been interested in stable isotope techniques for tracking and discriminating AN sources. Separate analysis of the AN component ions ammonium and nitrate would add discriminatory power to these techniques. Ammonium ions in dissolved AN solution were isolated from samples by precipitation using sodium tetraphenylborate solution. We tested the isolation of ammonium from nitrates using solutions of ammonium and nitrate salts with different (15)N/(14)N isotope ratios. Ammonium tetraphenylborate and AN were separately analyzed for their (15)N/(14)N isotope ratios using EA-ConFlo-IRMS, and the (15)N/(14)N isotope ratios of the nitrate ions were calculated using mass balance. Ammonium and nitrate nitrogen isotope ratios were plotted as two separate variables. Isolation of ammonium precipitate from solutions containing dissolved nitrates did not influence the nitrogen isotope ratios of test ammonium salts. A survey set of 42 AN samples showed that the ammonium and nitrate (15)N/(14)N isotope ratios were not significantly correlated, and the paired mean differences were not statistically significant. Both ammonium and nitrate were depleted in (15)N relative to their theoretical atmospheric sources. Isolation of the ammonium ion from AN adds another dimension for the discrimination of forensic AN samples. This technique using sodium tetraphenylborate is robust and does not require specialized equipment. Our observations indicated that ammonium nitrogen and nitrate nitrogen have independent sources of isotopic variation. Copyright © 2014 John Wiley & Sons, Ltd.

  10. Mass-dependent and -independent mercury stable isotope fractionation in the atmosphere (Invited) (United States)

    Blum, J. D.


    Mercury (Hg) is a geochemically unique atmospheric trace gas that has attracted considerable interest because it is globally distributed and once deposited can form the neurotoxin methylmercury. The study of Hg stable isotopes in the atmosphere provides a new tool for investigating reaction pathways in the atmosphere and for tracing the sources and fate of anthropogenic Hg. The speciation of Hg in the atmosphere is generally reported as three operationally defined forms: gaseous elemental mercury [Hg(0)gas], reactive gaseous mercury [(Hg(II)gas] and particulate mercury [(Hg(II)part]. Hg(0)gas has a relatively long atmospheric residence time of ~1 year, but once it is oxidized to Hg(II)gas it becomes reactive and is rapidly deposited in precipitation or attaches to particles and is deposited as Hg(II)part. Mercury undergoes both mass-dependent isotope fractionation (MDF) and mass-independent isotope fractionation (MIF) of the odd isotopes of Hg. MIF is believed to occur mainly during short-lived radical pair reactions due to the magnetic isotope effect, in which the magnetic spin of the odd isotopes influences singlet to triplet and triplet to singlet intersystem crossing. As a result, reaction products can be either enriched or depleted in the odd isotopes of Hg depending on whether singlet or triplet radical pairs are produced photochemically. Microbial and dark abiotic reduction of Hg(II) to Hg(0), and evaporation of Hg(0)gas lead mainly to MDF with light isotopes released preferentially to the atmosphere. Photochemical reduction of Hg(II) to Hg(0) produces MIF with release of Hg(0) either enriched or depleted in the odd isotopes, depending on the ligand with which Hg(II) is associated. Photochemical reduction of Hg(II) associated with natural organic matter dissolved in water produces Hg(0)gas with odd isotope depletion whereas photochemical reduction of Hg associated with halogens in snow produces odd isotope enrichment. The oxidation of Hg(0) by

  11. Stable isotope fractionation of tungsten during adsorption on Fe and Mn (oxyhydr)oxides (United States)

    Kashiwabara, Teruhiko; Kubo, Sayuri; Tanaka, Masato; Senda, Ryoko; Iizuka, Tsuyoshi; Tanimizu, Masaharu; Takahashi, Yoshio


    The similar, but not identical chemical properties of W compared with Mo suggest that the stable isotope system of W could be a novel proxy to explore the modern and ancient ocean as is the case in the well-established utility of Mo isotopes. We experimentally investigated the isotopic fractionation of W during adsorption on Fe and Mn (oxyhydr)oxides (ferrihydrite and δ-MnO2), a key process in the global ocean budget of this element. Our adsorption experiments confirmed that W isotopes fractionate substantially on both ferrihydrite and δ-MnO2: lighter W isotopes are preferentially adsorbed on both oxides as a result of equilibrium isotopic exchange between dissolved and adsorbed species, and the obtained values of Δ186/183Wliquid-solid (= δ186Wdissolved - δ186Wadsorbed) are 0.76 ± 0.09‰ for ferrihydrite and 0.88 ± 0.21‰ for δ-MnO2 (2σ, n = 6). Compared with the case of Mo isotopes, fractionation of W isotopes is (i) of comparable magnitude between ferrihydrite and δ-MnO2, and (ii) much smaller than that of Mo on δ-MnO2. Our previous XAFS observations and newly-performed DFT calculations both indicate that the observed W isotopic fractionations are caused by the symmetry change from Td (tetrahedral) WO42- to distorted Oh (octahedral) monomeric W species via formation of inner-sphere complexes on both ferrihydrite and δ-MnO2. The similar isotopic fractionations between the two oxides relate to the strong tendency for W to form inner-sphere complexes, which causes the symmetry change, in contrast to the outer-sphere complex of Mo on ferrihydrite. The smaller isotopic fractionation of W compared with Mo on δ-MnO2 despite their similar molecular symmetry seems to be due to their different degrees of distortion of Oh species. Our findings imply that the isotopic composition of W in modern oxic seawater is likely to become heavier relative to the input by removal of lighter W isotopes via adsorption on ferromanganese oxides in analogy with the Mo isotope

  12. Enhanced understanding of ectoparasite–host trophic linkages on coral reefs through stable isotope analysis

    Directory of Open Access Journals (Sweden)

    Amanda W.J. Demopoulos


    Full Text Available 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 δ13C and δ15N 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 δ13C 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.

  13. Effects of caloric restriction on nitrogen and carbon stable isotope ratios in adult rat bone. (United States)

    Robertson, Kimberly L; Rowland, Neil E; Krigbaum, John


    Stable isotope analysis is a valuable technique for dietary estimation in ecological and archaeological research, yet many variables can potentially affect tissue stable isotope signatures. Controlled feeding studies across a range of species have consistently demonstrated impacts of caloric restriction on tissue stable isotope ratios, but most have focused on juvenile, fasting, and/or starving individuals, and most have utilized soft tissues despite the importance of bone for paleodietary analyses. The goal of this study was to determine whether temporally defined, moderate food restriction could affect stable carbon and/or nitrogen isotope ratios in adult mammalian bone - a tissue that arguably reflects long-term dietary signals. Adult rats fed a standard laboratory diet were restricted to 45% of ad libitum intakes for 3 or 6 months. Relevant anatomical and physiological parameters were measured to confirm that the restriction protocol resulted in significant nutritional stress and to provide independent data to facilitate interpretation of stable isotope ratios. Femoral bone δ(13)Ccollagen, δ(15)Ncollagen, and δ(13)Capatite values were determined by isotope ratio mass spectrometry. Calorie-restricted animals exhibited a small, yet significant enrichment in (15)Ncollagen compared with control animals, reflecting protein-calorie stress. While the δ(13)Ccollagen values did not differ, the δ(13)Capatite values revealed less enrichment in (13)C than in controls, reflecting catabolism of body fat. Independent anatomical and physiological data from these same individuals support these interpretations. Results indicate that moderate caloric restriction does not appreciably undermine broad interpretations of dietary signals in adult mammalian bone. Significant variability among individuals or groups, however, is best explained by marked differences in energy intake over variable timescales. An inverse relationship between the δ(13)Capatite and δ(15)Ncollagen

  14. Enhanced understanding of ectoparasite: host trophic linkages on coral reefs through stable isotope analysis (United States)

    Demopoulos, Amanda W. J.; Sikkel, Paul C.


    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 δ13C and δ15N 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 in13C 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 δ13C 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.

  15. Particular geoscientific perspectives on stable isotope analysis in the arboreal system (United States)

    Helle, Gerhard; Balting, Daniel; Pauly, Maren; Slotta, Franziska


    In geosciences stable isotopes of carbon, oxygen and hydrogen from the tree ring archive have been used for several decades to trace the course of past environmental and climatological fluctuations. In contrast to ice cores, the tree ring archive is of biological nature (like many other terrestrial archives), but provides the opportunity to establish site networks with very high resolution in space and time. Many of the basic physical mechanisms of isotope shifts are known, but biologically mediated processes may lead to isotope effects that are poorly understood. This implies that the many processes within the arboreal system leading to archived isotope ratios in wood material are governed by a multitude of environmental variables that are not only tied to the isotopic composition of atmospheric source values (precipitation, CO2), but also to seasonally changing metabolic flux rates and pool sizes of photosynthates within the trees. Consequently, the extraction of climate and environmental information is particularly challenging and reconstructions are still of rather qualitative nature. Over the last 10 years or so, monitoring studies have been implemented to investigate stable isotope, climate and environmental signal transfer within the arboreal system to develop transfer or response functions that can translate the relevant isotope values extracted from tree rings into climate or other environmental variables. To what extent have these efforts lead to a better understanding that helps improving the meaningfulness of tree ring isotope signals? For example, do monitoring studies help deciphering the causes for age-related trends in tree ring stable isotope sequences that are published in a growing number of papers. Are existing monitoring studies going into detail enough or is it already too much effort for the outcome? Based on what we know already particularly in mesic habitats, tree ring stable isotopes are much better climate proxies than other tree ring

  16. The conflict between cheetahs and humans on Namibian farmland elucidated by stable isotope diet analysis.

    Directory of Open Access Journals (Sweden)

    Christian C Voigt

    Full Text Available Large areas of Namibia are covered by farmland, which is also used by game and predator species. Because it can cause conflicts with farmers when predators, such as cheetahs (Acinonyx jubatus, hunt livestock, we assessed whether livestock constitutes a significant part of the cheetah diet by analysing the stable isotope composition of blood and tissue samples of cheetahs and their potential prey species. According to isotopic similarities, we defined three isotopic categories of potential prey: members of a C4 food web with high δ15N values (gemsbok, cattle, springhare and guinea fowl and those with low δ15N values (hartebeest, warthog, and members of a C3 food web, namely browsers (eland, kudu, springbok, steenbok and scrub hare. We quantified the trophic discrimination of heavy isotopes in cheetah muscle in 9 captive individuals and measured an enrichment for 15N (3.2‰ but not for 13C in relation to food. We captured 53 free-ranging cheetahs of which 23 were members of groups. Cheetahs of the same group were isotopically distinct from members of other groups, indicating that group members shared their prey. Solitary males (n = 21 and males in a bachelor groups (n = 11 fed mostly on hartebeest and warthogs, followed by browsers in case of solitary males, and by grazers with high δ15N values in case of bachelor groups. Female cheetahs (n = 9 predominantly fed on browsers and used also hartebeest and warthogs. Mixing models suggested that the isotopic prey category that included cattle was only important, if at all, for males living in bachelor groups. Stable isotope analysis of fur, muscle, red blood cells and blood plasma in 9 free-ranging cheetahs identified most individuals as isotopic specialists, focussing on isotopically distinct prey categories as their food.

  17. Pollen-based reconstruction of Holocene climate variability in the Eifel region evaluated with stable isotopes (United States)

    Kühl, Norbert; Moschen, Robert; Wagner, Stefanie


    Pollen as well as stable isotopes have great potential as climate proxy data. While variability in these proxy data is frequently assumed to reflect climate variability, other factors than climate, including human impact and statistical noise, can often not be excluded as primary cause for the observed variability. Multiproxy studies offer the opportunity to test different drivers by providing different lines of evidence for environmental change such as climate variability and human impact. In this multiproxy study we use pollen and peat humification to evaluate to which extent stable oxygen and carbon isotope series from the peat bog "Dürres Maar" reflect human impact rather than climate variability. For times before strong anthropogenic vegetation change, isotope series from Dürres Maar were used to validate quantitative reconstructions based on pollen. Our study site is the kettle hole peat bog "Dürres Maar" in the Eifel low mountain range, Germany (450m asl), which grew 12m during the last 10,000 years. Pollen was analysed with a sum of at least 1000 terrestrial pollen grains throughout the profile to minimize statistical effects on the reconstructions. A recently developed probabilistic indicator taxa method ("pdf-method") was used for the quantitative climate estimates (January and July temperature) based on pollen. For isotope analysis, attention was given to use monospecific Sphagnum leaves whenever possible, reducing the potential of a species effect and any potential artefact that can originate from selective degradation of different morphological parts of Sphagnum plants (Moschen et al., 2009). Pollen at "Dürres Maar" reflect the variable and partly strong human impact on vegetation during the last 4000 years. Stable isotope time series were apparently not influenced by human impact at this site. This highlights the potential of stable isotope investigations from peat for climatic interpretation, because stable isotope series from lacustrine

  18. Stable isotope ratio analysis for authentication of red yeast rice. (United States)

    Perini, Matteo; Carbone, Gianfranco; Camin, Federica


    Red yeast rice (RYR) is a dietary supplement obtained from rice fermented with the mould Monascus purpureus. It contains Monacolin K which is a hypocholesterolemic statin used to prevent cardiovascular diseases. The homologous prescription biosynthetic statin, lovastatin, is not chemically distinguishable from monacolin K. In this work we investigated whether δ(13)C and δ(2)H can distinguish monacolin K from lovastatin and can detect the presence of lovastatin in RYR. 18 samples of red yeast rice powder and 18 samples of lovastatin were collected. Monacolin K was isolated from RYR using preparative HPLC and together with lovastatin, was subjected to analysis of δ(13)C and δ(2)H using Isotope Ratio Mass Spectrometry. Thanks to the different photosynthetic cycles of the matrices used for their synthesis, monacolin K and lovastatin have different δ(13)C values (-29.6‰ ± 0.6 and -16.7‰ ± 2.6 respectively). δ(2)H is significantly (p < 0.001) lower in monacolin K but the ranges of values partially overlap with those of lovastatin. By defining a δ(13)C threshold value of -28.3‰ for monacolin K, addition of lovastatin from a minimum of 10% can be identified. δ(13)C analysis can be therefore proposed as a suitable tool for detecting the authenticity of RYR on the market. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Groundwater stable isotope profile of the Etosha National Park, Namibia

    Directory of Open Access Journals (Sweden)

    Edward S. Riddell


    Full Text Available The Etosha National Park (ENP is a large protected area in northern Namibia. While the ENP has received a lot of research attention in terms of terrestrial ecosystem process understanding in recent decades, aquatic and hydrological research has to date been limited to a descriptive form. This study provides a baseline hydrological data set of the spatial representation of Oand H-isotope ratios in the groundwater at a park scale, with a focus on three water point types utilised by game, namely natural artesian and contact springs as well as artificial boreholes. The data are used to infer broad-scale hydrological process from groundwater recharge mechanisms dominated by direct rainfall recharge in the west of the ENP to evaporative controls on surface water recharge pathways in the east of the ENP close to Fishers Pan. The findings are used to recommend further targeted research and monitoring to aid management of water resources in the ENP.Conservation implications: The terrestrial ecosystem, particularly large game, are tightly coupled to the distribution of available surface water in the ENP, notably contact and artesian springs. Within the ENP there is a perceived desiccation of these springs. This study provides a baseline upon which more comprehensive studies should be undertaken to differentiate natural from anthropogenic causes for this phenomenon.

  20. Utilizing Stable Isotopes and Isotopic Anomalies to Study Early Solar System Formation Processes (United States)

    Simon, Justin


    Chondritic meteorites contain a diversity of particle components, i.e., chondrules and calcium-, aluminum-rich refractory inclusions (CAIs), that have survived since the formation of the Solar System. The chemical and isotopic compositions of these materials provide a record of the conditions present in the protoplanetary disk where they formed and can aid our understanding of the processes and reservoirs in which solids formed in the solar nebula, an important step leading to the accretion of planetesimals. Isotopic anomalies associated with nucleosynthetic processes are observed in these discrete materials, and can be compared to astronomical observations and astrophysical formation models of stars and more recently proplyds. The existence and size of these isotopic anomalies are typically thought to reflect a significant state of isotopic heterogeneity in the earliest Solar System, likely left over from molecular cloud heterogeneities on the grain scale, but some could also be due to late stellar injection. The homogenization of these isotopic anomalies towards planetary values can be used to track the efficiency and timescales of disk wide mixing,

  1. An Investigation into the Relationship Between Distillate Yield and Stable Isotope Fractionation (United States)

    Sowers, T.; Wagner, A. J.


    Recent breakthroughs in laser spectrometry have allowed for faster, more efficient analyses of stable isotopic ratios in water samples. Commercially available instruments from Los Gatos Research and Picarro allow users to quickly analyze a wide range of samples, from seawater to groundwater, with accurate isotope ratios of D/H to within ± 0.2 ‰ and 18O/16O to within ± 0.03 ‰. While these instruments have increased the efficiency of stable isotope laboratories, they come with some major limitations, such as not being able to analyze hypersaline waters. The Los Gatos Research Liquid Water Isotope Analyzer (LWIA) can accurately and consistently measure the stable isotope ratios in waters with salinities ranging from 0 to 4 grams per liter (0 to 40 parts per thousand). In order to analyze water samples with salinities greater than 4 grams per liter, however, it was necessary to develop a consistent method through which to reduce salinity while causing as little fractionation as possible. Using a consistent distillation method, predictable fractionation of δ 18O and δ 2 H values was found to occur. This fractionation occurs according to a linear relationship with respect to the percent yield of the water in the sample. Using this method, samples with high salinity can be analyzed using laser spectrometry instruments, thereby enabling laboratories with Los Gatos or Picarro instruments to analyze those samples in house without having to dilute them using labor-intensive in-house standards or expensive premade standards.

  2. Avian embryonic development does not change the stable isotope composition of the calcite eggshell. (United States)

    Maurer, G; Portugal, S J; Boomer, I; Cassey, P


    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 δ(13)C and δ(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.

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

    Directory of Open Access Journals (Sweden)

    Petrella Emma


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

  4. Mercury stable isotope fractionation during reduction of Hg(II) by different microbial pathways. (United States)

    Kritee, K; Blum, Joel D; Barkay, Tamar


    Mercury (Hg) stable isotope fractionation has recently been developed as a tool in biogeochemistry. In this study, the extent of Hg stable isotope fractionation during reduction of ionic mercury [Hg(II)] by two Hg(II)-resistant strains, Bacillus cereus 5 and the thermophile Anoxybacillus sp. FB9 [which actively detoxify Hg(II) by the mer system] and a Hg(II)-sensitive metal-reducing anaerobe, Shewanella oneidensis MR-1 [which reduces Hg(II) at low concentrations], was investigated. In all cases, barring suppression of fractionation that is likely due to lower Hg(II) bioavailability, the Hg(II) remaining in the reactor became progressively enriched with heavy isotopes with time and underwent mass-dependent Rayleigh fractionation with alpha202/198 values of 1.0016 +/- 0.0004 (1 SD). Based on a multistep framework for the Hg(II) reduction pathways in the three strains, we constrain the processes that could contribute toward fractionation and suggest that for Hg(II)-resistant strains, reduction by mercuric reductase is the primary step causing fractionation. The proposed framework helps explain the variation in the extent of Hg stable isotope fractionation during microbial reduction of Hg(II), furthering the promise of Hg isotope ratios as a tool in determining the role of microbial Hg transformations in the environment.

  5. Trophic structure in a seabird host-parasite food web: insights from stable isotope analyses.

    Directory of Open Access Journals (Sweden)

    Elena Gómez-Díaz

    Full Text Available Ecological studies on food webs rarely include parasites, partly due to the complexity and dimensionality of host-parasite interaction networks. Multiple co-occurring parasites can show different feeding strategies and thus lead to complex and cryptic trophic relationships, which are often difficult to disentangle by traditional methods. We analyzed stable isotope ratios of C ((13C/(12C, delta(13C and N ((15N/(14N, delta(15N of host and ectoparasite tissues to investigate trophic structure in 4 co-occurring ectoparasites: three lice and one flea species, on two closely related and spatially segregated seabird hosts (Calonectris shearwaters. delta(13C isotopic signatures confirmed feathers as the main food resource for the three lice species and blood for the flea species. All ectoparasite species showed a significant enrichment in delta(15N relatively to the host tissue consumed (discrimination factors ranged from 2 to 5 per thousand depending on the species. Isotopic differences were consistent across multiple host-ectoparasite locations, despite of some geographic variability in baseline isotopic levels. Our findings illustrate the influence of both ectoparasite and host trophic ecology in the isotopic structuring of the Calonectris ectoparasite community. This study highlights the potential of stable isotope analyses in disentangling the nature and complexity of trophic relationships in symbiotic systems.

  6. Application of Stable Isotope-Assisted Metabolomics for Cell Metabolism Studies

    Directory of Open Access Journals (Sweden)

    Le You


    Full Text Available The applications of stable isotopes in metabolomics have facilitated the study of cell metabolisms. Stable isotope-assisted metabolomics requires: (1 properly designed tracer experiments; (2 stringent sampling and quenching protocols to minimize isotopic alternations; (3 efficient metabolite separations; (4 high resolution mass spectrometry to resolve overlapping peaks and background noises; and (5 data analysis methods and databases to decipher isotopic clusters over a broad m/z range (mass-to-charge ratio. This paper overviews mass spectrometry based techniques for precise determination of metabolites and their isotopologues. It also discusses applications of isotopic approaches to track substrate utilization, identify unknown metabolites and their chemical formulas, measure metabolite concentrations, determine putative metabolic pathways, and investigate microbial community populations and their carbon assimilation patterns. In addition, 13C-metabolite fingerprinting and metabolic models can be integrated to quantify carbon fluxes (enzyme reaction rates. The fluxome, in combination with other “omics” analyses, may give systems-level insights into regulatory mechanisms underlying gene functions. More importantly, 13C-tracer experiments significantly improve the potential of low-resolution gas chromatography-mass spectrometry (GC-MS for broad-scope metabolism studies. We foresee the isotope-assisted metabolomics to be an indispensable tool in industrial biotechnology, environmental microbiology, and medical research.

  7. Seasonal variations in CH_{4} emissions and stable isotope signatures from an ombrotrophic peat bog (United States)

    Takriti, Mounir; Ward, Sue; Wynn, Peter; Rose, Rob; Dodd, Beverly; Chadwick, Alexander; Oakley, Simon; McNamara, Niall


    Natural wetlands are the largest source of CH4 emissions globally. However, despite a wealth of literature and field measurements, there is still considerable uncertainty about total emissions, largely due to the high seasonal and inter-annual variability in fluxes. The use of Stable isotopes provides a powerful technique for investigating CH4 biogeochemistry. In order to better constrain wetland greenhouse gas emissions we need to improve our understanding of how emissions and their isotopic signatures respond to seasonal changes in environmental controls. In peatlands, part of the CH4 produced under anaerobic conditions may be oxidised by methanotrophic bacteria in the top aerobic layer of the peat. Both microbial CH4 production and oxidation will be driven by environmental conditions, but may show independent responses, while their relative magnitude will affect total emissions and their isotopic signature. In order to improve our understanding of these important processes in wetland CH4 emissions we set up a 12-month study at an ombrotrophic peat bog in northern England. Weekly chamber flux measurements were combined with monthly stable isotope (13C/12C, 2H/1H) measurements, climate, and soil parameters to investigate how seasonal changes in environmental conditions affect CH4 fluxes and their isotopic signatures as an indicator of the balance between CH4 production and oxidation. We show a seasonal pattern in total emissions with higher fluxes in summer and autumn, and expect to find a concomitant seasonal pattern in isotope signatures due to changes in the relative activity of methanotrophs.

  8. Identification of miRNA targets with stable isotope labeling by amino acids in cell culture

    DEFF Research Database (Denmark)

    Vinther, Jeppe; Hedegaard, Mads Marquardt; Gardner, Paul Phillip


    miRNAs are small noncoding RNAs that regulate gene expression. We have used stable isotope labeling by amino acids in cell culture (SILAC) to investigate the effect of miRNA-1 on the HeLa cell proteome. Expression of 12 out of 504 investigated proteins was repressed by miRNA-1 transfection...


    Directory of Open Access Journals (Sweden)

    E. Novelli


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

  10. You Are What You Eat: Mass spectrometry in paediatric kinetic studies using stable isotopes

    NARCIS (Netherlands)

    H. Schierbeek (Henk)


    textabstractAn overview will be presented about applications of stable isotopes in paediatric research. Mass spectrometry has proven to be an essential tool for unravelling kinetic studies in a large range of different research disciplines related to intestinal diseases, obesities, severe cerebral

  11. Can δ15N and δ13C stable isotopes and fatty acid signatures ...

    African Journals Online (AJOL)

    Temporal changes in fatty acid composition and δ15N, δ13C stable isotope values of the phytobenthos growing on artificial clay substrates under natural conditions over a 28-day period at an upstream and a downstream site in the Kowie River near Grahamstown were investigated in 2012. High concentrations of diatom ...

  12. Stable isotope dilution analysis of orotic acid and uracil in amniotic fluid

    NARCIS (Netherlands)

    Jakobs, C.; Sweetman, L.; Nyhan, W.L.; Gruenke, L.; Craig, J.C.; Wadman, S.K.


    Rapid, sensitive and accurate stable isotope dilution assays were developed for the measurement of orotic acid and uracil in amniotic fluid. The method utilizes [15N2]orotic acid and [15N2]uracil as internal standards, isolation by liquid partition chromatography and quantitation by chemical

  13. Stable isotope evidence of food web connectivity by a top predatory ...

    African Journals Online (AJOL)

    Stable isotope evidence of food web connectivity by a top predatory fish ( Argyrosomus japonicus : Sciaenidae: Teleostei) in the Kowie Estuary, South Africa. ... within the Kowie Estuary on the south-east coast of South Africa was evidenced by the trophic behaviour of the predominantly piscivorous Argyrosomus japonicus.

  14. Stable isotopes' as trophic tracers: combining field sampling and manipulative labelling of food resources for macrobenthos

    NARCIS (Netherlands)

    Herman, P.M.J.; Middelburg, J.J.; Widdows, J.; Lucas, C.M.; Heip, C.H.R.


    We combined 3 different approaches to determine the relative importance of microphytobenthos production as food for intertidal macrobenthic animals: (1) the natural abundance of stable-isotope ratios of carbon and nitrogen, (2) an in situ deliberate tracer addition of C-13-bicarbonate, which was

  15. Influence of forest disturbance on stable nitrogen isotope ratios in soil and vegetation profiles (United States)

    Jennifer D. Knoepp; Scott R. Taylor; Lindsay R. Boring; Chelcy F. Miniat


    Soil and plant stable nitrogen isotope ratios (15 N) are influenced by atmospheric nitrogen (N) inputs and processes that regulate organic matter (OM) transformation and N cycling. The resulting 15N patterns may be useful for discerning ecosystem differences in N cycling. We studied two ecosystems; longleaf pine wiregrass (...

  16. Stable Isotope Values of Nitrogen and Carbon in Particulate Matter: Data (United States)

    Data set from “Patterns in stable isotope values of nitrogen and carbon in particulate matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras” by Oczkowski et al. These are the data upon which all results and conclusion are made...

  17. Using Stable Isotopes of Carbon and Nitrogen to Evaluate Trophic Interactions in Aquatic Environments (United States)

    Christensen, David R.; LaRoche, Andrew


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

  18. Combining Stable Isotope Labeling and Molecular Networking for Biosynthetic Pathway Characterization

    DEFF Research Database (Denmark)

    Klitgaard, Andreas; Nielsen, Jakob Blæsbjerg; Frandsen, Rasmus John Normand


    Filamentous fungi are a rich source of bioactive compounds, ranging from statins over immunosuppressants to antibiotics. The coupling of genes to metabolites is of large commercial interest for production of the bioactives of the future. To this end, we have investigated the use of stable isotope...

  19. Continental-Scale Stable Isotope Measurements at NEON to Address Ecological Processes Across Systems (United States)

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


    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.

  20. Tracing Raw Materials of Commercially-supplied Mirin by Carbon Stable Isotope Analysis

    National Research Council Canada - National Science Library

    IZU, Hanae; HASHIGUCHI, Tomokazu; HASHIMOTO, Tomoko; MATSUMARU, Katsumi


      In this study, we determined the carbon stable isotope ratios of the extract (δ13CEx) and alcohol (δ13CAlc) in commercially-supplied Mirin in order to confirm them as a potential index for verifying the raw-material origins...

  1. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    Van Duyl, F.C.; Moodley, L.; Nieuwland, G.; Van IJzerloo, L.P.; Van Soest, R.W.M.; Houtekamer, M.J.; Meesters, E.H.W.G.; Middelburg, J.J.


    The diet of cavity sponges on the narrow fringing reefs of Curac¸ao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found that

  2. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    Duyl, van F.C.; Moodley, L.; Nieuwland, G.; Ijzerloo, van L.; Soest, R.W.M.; Houtekamer, M.; Meesters, H.W.G.; Middelburg, J.J.


    The diet of cavity sponges on the narrow fringing reefs of Cura double dagger ao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found

  3. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    van Duyl, F.C.; Moodley, L.; Nieuwland, G.; van IJzerloo, L.; van Soest, R.W.M.; Houtekamer, M.; Meesters, E.H.; Middelburg, J.J.


    The diet of cavity sponges on the narrow fringing reefs of Curaçao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found that

  4. Food choice of Antarctic soil arthopods clarified by stable isotope signatures.

    NARCIS (Netherlands)

    Bokhorst, S.F.; Ronfort, C.; Huiskes, A.; Convey, P.; Aerts, R.


    Antarctic soil ecosystems are amongst the most simplified on Earth and include only few soil arthropod species, generally believed to be opportunistic omnivorous feeders. Using stable isotopic analyses, we investigated the food choice of two common and widely distributed Antarctic soil arthropod

  5. Food choice of Antarctic soil arthropods clarified by stable isotope signatures

    NARCIS (Netherlands)

    Bokhorst, S.F.; Ronfort, C.; Huiskes, A.H.L.; Convey, P.; Aerts, R.A.M.


    Antarctic soil ecosystems are amongst the most simplified on Earth and include only few soil arthropod species, generally believed to be opportunistic omnivorous feeders. Using stable isotopic analyses, we investigated the food choice of two common and widely distributed Antarctic soil arthropod

  6. You are what you eat: stable isotope ecology of owl diets in Alberta, Canada (United States)

    James M. Duxbury; Geoffery 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...

  7. Water enriched in the rare stable isotopes : Preparation, measurement and applications

    NARCIS (Netherlands)

    Faghihi, Vahideh


    The subject of this thesis is water with increased abundances of the rare stable isotopes 2H and 18O (and to some extent also 17O). Such artificially enriched (or "labelled") waters are often used in biomedicine, for establishing the total amount of body water (and thus body composition) of humans

  8. Stable isotope analysis of fish mucus during a controlled diet switch (United States)

    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...

  9. Analysis of stable isotopes in fish mucus during a controlled diet switch (United States)

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

    NARCIS (Netherlands)

    Zuiderweg, A.T.; Holzinger, R.; Roeckmann, T.


    We present setup, testing and initial results from a new automated system for stable carbon isotope ratio measurements on C2 to C6 atmospheric hydrocarbons. The inlet system allows analysis of trace gases from air samples ranging from a few liters for urban samples and samples with high mixing

  11. Patterns in stable isotope ratios of particulate material from the eastern US continental shelf (United States)

    Stable isotope measurements of nitrogen and carbon (δ15N, δ13C) in estuarine, nearshore, and open ocean ecosystems are often utilized in order to characterize human influences, elucidate food web dynamics, or better understand nitrogen cycling. Reliable information a...

  12. Breath carbon stable isotope ratios identify changes in energy balance and substrate utilization in humans (United States)

    Rapid detection of shifts in substrate utilization and energy balance would provide a compelling biofeedback tool to enable individuals to lose weight. In a pilot study, we tested whether the natural abundance of exhaled carbon stable isotope ratios (breath d13C values) reflects shifts between negat...

  13. Tracking Seasonal Habitats Using Carbon and Nitrogen Stable Isotopes of Osprey Primary Flight Feathers (United States)

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


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

  14. Experimental Evaluation of Stable Isotope Fractionation in Fish Muscle and Otoliths (United States)

    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 δ13C and δ15N between diet and muscle, and assessed if fractionation was consistent...

  15. Stable carbon isotope fractionation of organic cyst-forming dinoflagellates: Evaluating the potential for a CO

    NARCIS (Netherlands)

    Hoins, M.; Van de Waal, D.B.; Eberlein, T.; Reichart, G.-J.; Rost, B.; Sluijs, A.


    Over the past decades, significant progress has been made regarding the quantification and mechanistic understanding of stable carbon isotope fractionation (13C fractionation) in photosynthetic unicellular organisms in response to changes in the partial pressure of atmospheric CO2 (pCO2). However,

  16. Variation in carbon and nitrogen stable isotope ratios in flight feathers of a moulting White-bellied Sunbird Cinnyris talatala

    CSIR Research Space (South Africa)

    Symes, CT


    Full Text Available The authors measured d13C and d15N isotope signatures in flight feathers of a White-bellied Sunbird to assess the value of using stable isotopes of feathers in avian dietary studies. Significant variation in d13C and d15N isotope values of flight...

  17. Paired stable isotopes (O, C) and clumped isotope thermometry of magnesite and silica veins in the New Caledonia Peridotite Nappe (United States)

    Quesnel, Benoît; Boulvais, Philippe; Gautier, Pierre; Cathelineau, Michel; John, Cédric M.; Dierick, Malorie; Agrinier, Pierre; Drouillet, Maxime


    The stable isotope compositions of veins provide information on the conditions of fluid-rock interaction and on the origin of fluids and temperatures. In New Caledonia, magnesite and silica veins occur throughout the Peridotite Nappe. In this work, we present stable isotope and clumped isotope data in order to constrain the conditions of fluid circulation and the relationship between fluid circulation and nickel ore-forming laterization focusing on the Koniambo Massif. For magnesite veins occurring at the base of the nappe, the high δ18O values between 27.8‰ and 29.5‰ attest to a low temperature formation. Clumped isotope analyses on magnesite give temperatures between 26 °C and 42 °C that are consistent with amorphous silica-magnesite oxygen isotope equilibrium. The meteoric origin of the fluid is indicated by calculated δ18Owater values between -3.4‰ to +1.5‰. Amorphous silica associated with magnesite or occurring in the coarse saprolite level displays a narrow range of δ18O values between 29.7‰ and 35.3‰. For quartz veins occurring at the top of the bedrock and at the saprolite level, commonly in association with Ni-talc-like minerals, the δ18O values are lower, between 21.8‰ and 29.0‰ and suggest low-temperature hydrothermal conditions (∼40-95 °C). Thermal equilibration of the fluid along the geothermic gradient before upward flow through the nappe and/or influence of exothermic reactions of serpentinization could be the source(s) of heat needed to form quartz veins under such conditions.

  18. Stable isotope anatomy of tropical cyclone Ita, North-Eastern Australia, April 2014. (United States)

    Munksgaard, Niels C; Zwart, Costijn; Kurita, Naoyuki; Bass, Adrian; Nott, Jon; Bird, Michael I


    The isotope signatures registered in speleothems during tropical cyclones (TC) provides information about the frequency and intensity of past TCs but the precise relationship between isotopic composition and the meteorology of TCs remain uncertain. Here we present continuous δ18O and δ2H data in rainfall and water vapour, as well as in discrete rainfall samples, during the passage of TC Ita and relate the evolution in isotopic compositions to local and synoptic scale meteorological observations. High-resolution data revealed a close relationship between isotopic compositions and cyclonic features such as spiral rainbands, periods of stratiform rainfall and the arrival of subtropical and tropical air masses with changing oceanic and continental moisture sources. The isotopic compositions in discrete rainfall samples were remarkably constant along the ~450 km overland path of the cyclone when taking into account the direction and distance to the eye of the cyclone at each sampling time. Near simultaneous variations in δ18O and δ2H values in rainfall and vapour and a near-equilibrium rainfall-vapour isotope fractionation indicates strong isotopic exchange between rainfall and surface inflow of vapour during the approach of the cyclone. In contrast, after the passage of spiral rainbands close to the eye of the cyclone, different moisture sources for rainfall and vapour are reflected in diverging d-excess values. High-resolution isotope studies of modern TCs refine the interpretation of stable isotope signatures found in speleothems and other paleo archives and should aim to further investigate the influence of cyclone intensity and longevity on the isotopic composition of associated rainfall.

  19. Nekton migration and feeding location in a coastal area - A stable isotope approach (United States)

    Vinagre, C.; Máguas, C.; Cabral, H. N.; Costa, M. J.


    Stable isotope analysis was used to investigate nekton movements and feeding location in a coastal area adjacent to a major European river, the Tagus, Portugal. Particulate organic matter isotopic signatures presented a gradient from the river towards the sea. Phytoplankton, zooplankton, polychaetes and the crab, Polybius henslowii, provided evidence of the incorporation of terrestrial organic matter into the lower levels of the food web, reflecting local isotopic signatures. Two fish species reflected the coastal isotopic gradient in δ13C, Diplodus vulgaris and Arnoglossus imperialis and the latter also presented isotopic differerences among the sites for δ15N. Alloteuthis subulata, Trisopterus luscus and Callionymus lyra were isotopicaly distinct among sites for δ15N. An increase of δ15N with length was detected for T. luscus and C. lyra, possibly showing ontogenic trophic level changes. Since A. subulata did not present differences in length and still showed isotopic distinction for δ15N, among areas, it was concluded that local biogeochemical factors may also have an influence. Diplodus bellottii and Dicologlossa cuneata did not reflect any isotopic signature reflecting their wide migration and feeding across the coastal area. Central isotopic ranges, defined as the site mean values for δ13C and δ15N ± 1‰ were determined for each species and site and those deviating from these were considered transient individuals. Central isotopic ranges accounted for 87% of A. imperialis, 80% of A. subulata, 77% of T. luscus, 67% of C. lyra and 50% of D. vulgaris. The number of individuals within each central isotopic range was surprisingly high for an open coastal area and comparable to those of more structured environments.

  20. Stable isotope anatomy of tropical cyclone Ita, North-Eastern Australia, April 2014.

    Directory of Open Access Journals (Sweden)

    Niels C Munksgaard

    Full Text Available The isotope signatures registered in speleothems during tropical cyclones (TC provides information about the frequency and intensity of past TCs but the precise relationship between isotopic composition and the meteorology of TCs remain uncertain. Here we present continuous δ18O and δ2H data in rainfall and water vapour, as well as in discrete rainfall samples, during the passage of TC Ita and relate the evolution in isotopic compositions to local and synoptic scale meteorological observations. High-resolution data revealed a close relationship between isotopic compositions and cyclonic features such as spiral rainbands, periods of stratiform rainfall and the arrival of subtropical and tropical air masses with changing oceanic and continental moisture sources. The isotopic compositions in discrete rainfall samples were remarkably constant along the ~450 km overland path of the cyclone when taking into account the direction and distance to the eye of the cyclone at each sampling time. Near simultaneous variations in δ18O and δ2H values in rainfall and vapour and a near-equilibrium rainfall-vapour isotope fractionation indicates strong isotopic exchange between rainfall and surface inflow of vapour during the approach of the cyclone. In contrast, after the passage of spiral rainbands close to the eye of the cyclone, different moisture sources for rainfall and vapour are reflected in diverging d-excess values. High-resolution isotope studies of modern TCs refine the interpretation of stable isotope signatures found in speleothems and other paleo archives and should aim to further investigate the influence of cyclone intensity and longevity on the isotopic composition of associated rainfall.

  1. Data-driven Approaches to Teaching Stable Isotopes in Hydrology and Environmental Geochemistry (United States)

    Jefferson, A.; Merchant, W. R.; Dees, D.; Griffith, E. M.; Ortiz, J. D.


    Stable isotopes have revolutionized our understanding of watershed hydrology and other earth science processes. However, students may struggle to correctly interpret isotope ratios and few students understand how isotope measurements are made. New laser-based technologies lower the barrier to entry for giving students hands on experience with isotope measurements and data analysis. We hypothesizedthat integrating such activities into the curriculum would increase student content knowledge, perceptions, and motivation to learn. This project assessed the impact that different pedagogical approaches have on student learning of stable isotope concepts in upper-division geoscience courses. An isotope hydrograph separation module was developed and taught for a Watershed Hydrology course, and a Rayleigh distillation activity was developed and deployed for Environmental Geochemistry and Sedimentology/Stratigraphy classes. Groups of students were exposed to this content via (1) a lecture-only format; (2) a paper-based data analysis activity; and (3) hands-on data collection, sometimes including spectrometer analysis. Pre- and post-tests measured gains in content knowledge while approaches to learning and motivational questionnaires instruments were used to identify the effects of the classroom environment on learning approaches and motivation. Focus group interviews were also conducted to verify the quantitative data. All instructional styles appear to be equally effective at increasing student content knowledge of stable isotopes in the geosciences, but future studies need to move beyond "exam question" style assessment of learning. Our results may reflect that hands-on experiences are not new to upper-level geosciences students, because this is the way that many classes are taught in the geosciences (labs, field trips). Thus, active learning approaches may not have had the impact they would with other groups. The "messiness" of hands-on activities and authentic research

  2. The First New Zealanders? An Alternative Interpretation of Stable Isotope Data from Wairau Bar, New Zealand.

    Directory of Open Access Journals (Sweden)

    Andrew A Brown

    Full Text Available PLOS ONE Volume 8 includes an article "The First New Zealanders: Patterns of Diet and Mobility Revealed through Isotope Analysis". The paper proposes that burial groups within the settlement phase site of Wairau Bar differ in terms of dietary stable isotopes and 87Sr/86Sr. The authors argue this difference is probably due to one group being a founding population while the other burials are later. Here we review the work of Kinaston et al. and present an alternative analysis and interpretation of the isotopic data. Treating the isotope data independently from cultural and biological factors we find that sex best explains dietary variation. Our reassessment of 87Sr/86Sr confirms the authors original finding of high mobility of early New Zealanders but suggests a larger range of individuals should be considered 'non-local' on current evidence.

  3. Unique Hg stable isotope signatures of compact fluorescent lamp-sourced Hg. (United States)

    Mead, Chris; Lyons, James R; Johnson, Thomas M; Anbar, Ariel D


    The recent widespread adoption of compact fluorescent lamps (CFL) has increased their importance as a source of environmental Hg. Stable isotope analysis can identify the sources of environmental Hg, but the isotopic composition of Hg from CFL is not yet known. Results from analyses of CFL with a range of hours of use show that the Hg they contain is isotopically fractionated in a unique pattern during normal CFL operation. This fractionation is large by comparison to other known fractionating processes for Hg and has a distinctive, mass-independent signature, such that CFL Hg could be uniquely identified from other sources. The fractionation process described here may also explain anomalous fractionation of Hg isotopes in precipitation.

  4. Inferring foraging areas of nesting loggerhead turtles using satellite telemetry and stable isotopes.

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    Simona A Ceriani

    Full Text Available In recent years, the use of intrinsic markers such as stable isotopes to link breeding and foraging grounds of migratory species has increased. Nevertheless, several assumptions still must be tested to interpret isotopic patterns found in the marine realm. We used a combination of satellite telemetry and stable isotope analysis to (i identify key foraging grounds used by female loggerheads nesting in Florida and (ii examine the relationship between stable isotope ratios and post-nesting migration destinations. We collected tissue samples for stable isotope analysis from 14 females equipped with satellite tags and an additional 57 untracked nesting females. Telemetry identified three post-nesting migratory pathways and associated non-breeding foraging grounds: (1 a seasonal continental shelf-constrained migratory pattern along the northeast U.S. coastline, (2 a non-breeding residency in southern foraging areas and (3 a residency in the waters adjacent to the breeding area. Isotopic variability in both δ(13C and δ(15N among individuals allowed identification of three distinct foraging aggregations. We used discriminant function analysis to examine how well δ(13C and δ(15N predict female post-nesting migration destination. The discriminant analysis classified correctly the foraging ground used for all but one individual and was used to predict putative feeding areas of untracked turtles. We provide the first documentation that the continental shelf of the Mid- and South Atlantic Bights are prime foraging areas for a large number (61% of adult female loggerheads from the largest loggerhead nesting population in the western hemisphere and the second largest in the world. Our findings offer insights for future management efforts and suggest that this technique can be used to infer foraging strategies and residence areas in lieu of more expensive satellite telemetry, enabling sample sizes that are more representative at the population level.

  5. Mercury contamination and stable isotopes reveal variability in foraging ecology of generalist California gulls (United States)

    Peterson, Sarah; Ackerman, Joshua T.; Eagles-Smith, Collin A.


    Environmental contaminants are a concern for animal health, but contaminant exposure can also be used as a tracer of foraging ecology. In particular, mercury (Hg) concentrations are highly variable among aquatic and terrestrial food webs as a result of habitat- and site-specific biogeochemical processes that produce the bioaccumulative form, methylmercury (MeHg). We used stable isotopes and total Hg (THg) concentrations of a generalist consumer, the California gull (Larus californicus), to examine foraging ecology and illustrate the utility of using Hg contamination as an ecological tracer under certain conditions. We identified four main foraging clusters of gulls during pre-breeding and breeding, using a traditional approach based on light stable isotopes. The foraging cluster with the highest δ15N and δ34S values in gulls (cluster 4) had mean blood THg concentrations 614% (pre-breeding) and 250% (breeding) higher than gulls with the lowest isotope values (cluster 1). Using a traditional approach of stable-isotope mixing models, we showed that breeding birds with a higher proportion of garbage in their diet (cluster 2: 63–82% garbage) corresponded to lower THg concentrations and lower δ15N and δ34S values. In contrast, gull clusters with higher THg concentrations, which were more enriched in 15N and 34S isotopes, consumed a higher proportion of more natural, estuarine prey. δ34S values, which change markedly across the terrestrial to marine habitat gradient, were positively correlated with blood THg concentrations in gulls. The linkage we observed between stable isotopes and THg concentrations suggests that Hg contamination can be used as an additional tool for understanding animal foraging across coastal habitat gradients.

  6. The use of stable isotopes in quantitative determinations of exogenous water and added ethanol in wines (United States)

    Magdas, D. A.; Moldovan, Z.; Cristea, G.


    The application of oxygen isotope ratios analysis to wine water according to EU regulation no. 822/97 to determine wine's origin and also, the possible water addition to wines, gained great importance in wines authenticity control. In the natural cycle of water isotopic fractionation, during water evaporation process, the water vapors are depleted in heavy isotopes. On the other hand inside the plants take place an isotope enrichment of heavy stable isotopes of water compared with meteoric water due to photosynthesis and plants transpiration. This process makes possible the detection of exogenous water from wines 18O/16O ratios. Carbon isotopic ratios were used to estimate the supplementary addition of ethanol obtained from C4 plants (sugar cane or corn). This work presents the way in which the isotopic fingerprints (δ13C and δ18O) were used to determine the content of exogenous water from wines and the added supplementary ethanol coming from C4 plants. By using this method, the calculated values obtained for the degree of wine adulteration were in a good agreement with the real exogenous percent of water and ethanol from investigated samples.

  7. Iron stable isotopes track pelagic iron cycling during a subtropical phytoplankton bloom. (United States)

    Ellwood, Michael J; Hutchins, David A; Lohan, Maeve C; Milne, Angela; Nasemann, Philipp; Nodder, Scott D; Sander, Sylvia G; Strzepek, Robert; Wilhelm, Steven W; Boyd, Philip W


    The supply and bioavailability of dissolved iron sets the magnitude of surface productivity for ∼ 40% of the global ocean. The redox state, organic complexation, and phase (dissolved versus particulate) of iron are key determinants of iron bioavailability in the marine realm, although the mechanisms facilitating exchange between iron species (inorganic and organic) and phases are poorly constrained. Here we use the isotope fingerprint of dissolved and particulate iron to reveal distinct isotopic signatures for biological uptake of iron during a GEOTRACES process study focused on a temperate spring phytoplankton bloom in subtropical waters. At the onset of the bloom, dissolved iron within the mixed layer was isotopically light relative to particulate iron. The isotopically light dissolved iron pool likely results from the reduction of particulate iron via photochemical and (to a lesser extent) biologically mediated reduction processes. As the bloom develops, dissolved iron within the surface mixed layer becomes isotopically heavy, reflecting the dominance of biological processing of iron as it is removed from solution, while scavenging appears to play a minor role. As stable isotopes have shown for major elements like nitrogen, iron isotopes offer a new window into our understanding of the biogeochemical cycling of iron, thereby allowing us to disentangle a suite of concurrent biotic and abiotic transformations of this key biolimiting element.

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

    Directory of Open Access Journals (Sweden)

    Michael J Polito

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

  9. Stable carbon isotope ratios of ambient secondary organic aerosols in Toronto (United States)

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


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

  10. Long-term data set analysis of stable isotopic composition in German rivers (United States)

    Reckerth, Anne; Stichler, Willibald; Schmidt, Axel; Stumpp, Christine


    Stable isotopes oxygen-18 (18O) and deuterium (2H) are commonly used to investigate hydrological processes in catchments. However, only a few isotope studies have been conducted on a large scale and rarely over long time periods. The objective of this study was to identify the spatial and seasonal variability of isotopic composition in river water and how it is affected by geographical and hydrological factors. The stable isotopic composition of river water has been measured in nine large river catchments in Germany for a time period of 12 years or 26 years. We conducted time series and correlation analyses to identify spatial and temporal patterns of the isotopic composition in the rivers. Further, we compared it to isotopic composition in local precipitation and catchments characteristics. In the majority of the rivers, the spatial and temporal patterns of precipitation were directly reflected in river water. The isotopic signals of the river water were time shifted and show attenuated amplitudes. Further deviations from isotopic compositions in local precipitation were observed in catchments with complex flow systems. These deviations were attributed to catchment processes and influences like evaporation, damming and storage. The seasonality of the isotopic composition was mainly determined by the discharge regimes of the rivers. We found correlations between isotopic long-term averages and catchment altitude as well as latitude and longitude, resulting in a northwest-southeast gradient. Furthermore, it was shown that long-term averages of d-excess were inversely related to flow length and catchment size, which indicates that evaporation enrichment has an impact on the isotopic composition even in catchments of humid climates. This study showed that isotopic composition in rivers can serve as a proxy for the local precipitation and can be utilized as an indicator for hydrological processes even in large river basins. In future, such long time series will help to

  11. Potential uses of stable isotope ratios of Sr, Nd, and Pb in geological materials for environmental studies. (United States)

    Nakano, Takanori


    The ratios of stable isotopes of certain elements in rocks and minerals have strong regional characteristics that are reflected in atmospheric components, in water, and in the living organisms that form Earth's surface environment as well as in agricultural and fishery products. Geologically derived stable isotope ratios can be used as a tracer for the source of many kinds of substances, with current geochemical techniques allowing the precise determination of numerous stable isotope ratios in both natural and manmade objects. This review presents examples of the use of stable isotopes as tracers within diverse dynamic ecosystems, focusing on Sr isotopes but also including examples of Nd and Pb isotopic analysis, and reviewing the potential of this technique for a wide range of environmental research, including determining the geographic origin of food and archeological materials.

  12. [Review of dual stable isotope technique for nitrate source identification in surface- and groundwater in China]. (United States)

    Xu, Zhi-Wei; Zhang, Xin-Yu; Yu, Gui-Rui; Sun, Xiao-Min; Wen, Xue-Fa


    Water nitrate (NO3-) contamination is a world-wide environmental problem under the effects of intensive human activities. Sources identification of NO3- contamination in water is important for better management of water quality. Dual stable isotope data of nitrate nitrogen (delta15N) and nitrate oxygen (delta18O) combined with other stable isotopes and chemical analysis data have been frequently used to identify NO3- sources, differentiate percentage of the different NO3- sources and assess the nitrification/denitrification processes of surface water, groundwater and precipitation, respectively. This review summarized the analysis technique of nitrate delta15N and delta18O in domestic and abroad, assessed typical values of delta15N, delta18O from different NO3- sources and evaluated the progress in application of dual stable isotope of delta15N and delta18O technique to trace NO3- sources in surface- and ground-water. Both ion exchange-AgNO3 and bacteria denitrifying methods have been successfully used in tracing water nitrate sources nationwide. The comprehensive metadata analysis of nitrate sources showed that the delta15N values of sewage and manure, soil, precipitation, fertilizer ranged from 3 per thousand to 17 per thousand, 3 per thousand to 8 per thousand, - 9 per thousand to 9 per thousand, -2 per thousand to 4 per thousand, respectively. And the delta15N values of ammonium fertilizer ranged from - 4 per thousand to 2 per thousand. According to the stable isotope technique, sewage and manure were identified as the major nitrate sources of surface- and ground-water in China. This indicated that municipal sewage and aquaculture exerted serious influence on the nitrate pollution of surface water. In the future, long-term monitoring, dual stable isotope fingerprinting and hydro-chemical analysis should be applied together to quantitatively differentiate contribution of nitrate sources, and to assess seasonal dynamic of nitrate sources. It will provide useful

  13. Stable isotope variations in precipitation: simulations and comparison with observations (Yunnan Plateau, High Asia

    Directory of Open Access Journals (Sweden)

    X. P. Zhang


    Full Text Available Stable isotopes in precipitation, both liquid (rain and solid (snow, can be suitable tracers for hydrological cycles because their concentrations reflect the cumulative record of physical phase changes. Distribution of stable isotopes in precipitation over High-Asian monsoon regions, including Yunnan Plateau is investigated. It has two noticeable features: firstly, the stable isotopes in precipitation distinctly decrease; and secondly, the stable isotopes in precipitation demonstrate smaller concentrations during rainy seasons and higher values during dry seasons. These features were found by the MUGCM simulation developed in the Melbourne Univertisty. Quantitative effect of the stable isotopes in precipitation takes place at different time scales, i.e. in diurnal, monthly or annual variations. Relative to observations, the simulated δ¹⁸O in precipitation shows stronger dependence on precipitation. In the diurnal course, the simulated regression equations of δ¹⁸O in precipitation versus precipitation amount are in good agreement with the observed values at Tengchong and Simao, except that the simulated δ¹⁸O/P curve slope is slightly smaller than the observed one at Mingzi. In the monthly and annual courses both, the simulated and observed δ¹⁸O/P slopes are smaller than it is in the diurnal course. For individual station, the local meteoric water line (LMWL is simulated well at Mengzi and Tengchong. However, the simulated result does not reproduce truly the observed relationship between δD and δ¹⁸O in precipitation at Simao and Kunming where the LMWL inclination is larger 8.0, and a shift along the y-axis higher 10.0. In addition, all simulated LMWL slopes are higher the observed ones at four stations, suggesting that the GCM can overestimate the decreasing of Hydrogen Deuterium Oxide and, thus, underestimate the second-order parameter, i.e. the deuterium excess, in a particular region Yunnan.

  14. Limnological controls on stable isotope records of late-holocene palaeoenvironment change in sw greenland: A paired lake study

    DEFF Research Database (Denmark)

    Olsen, Jesper; John Anderson, N.; Leng, M.J.


    Stable isotope records are increasingly being used in palaeoenvironmental studies of Arctic lakes. Here we compare stable isotope and elemental records (δ13C, δ15N, C/N) with high resolution XRF-derived geochemical and colour data from low Arctic lakes (SS1220 and SS85) in southwest Greenland. Lake...

  15. Tracing metal–silicate segregation and late veneer in the Earth and the ureilite parent body with palladium stable isotopes

    DEFF Research Database (Denmark)

    Creech, J. B.; Moynier, F.; Bizzarro, Martin


    Stable isotope studies of highly siderophile elements (HSE) have the potential to yield valuable insights into a range of geological processes. In particular, the strong partitioning of these elements into metal over silicates may lead to stable isotope fractionation during metal–silicate segrega...... with a late-veneer of chondritic material after core formation....

  16. The relationship between carbon stable isotope ratios of hatchling down and egg yolk in Black-headed Gulls

    NARCIS (Netherlands)

    Klaassen, M.R.J.; Baarspul, T.; Dekkers, T.; Van Tienen, P.


    We reconstructed the nutrient source for egg synthesis by sampling Black-headed Gull (Larus ridibundus) eggs for yolk, analyzing their carbon stable isotope ratio, and comparing that to hatchling down. Most of the variation in carbon stable isotope ratio was explained by differences between nests,

  17. Using variances in hydrocarbon concentration and carbon stable isotope to determine the important influence of irrigated water on petroleum accumulation in surface soil. (United States)

    Zhang, Juan; Wang, Renqing; Yang, Juncheng; Hou, Hong; Du, Xiaoming; Dai, Jiulan


    Hunpu is a wastewater-irrigated area southwest of Shenyang. To evaluate petroleum contamination and identify its sources at the area, the aliphatic hydrocarbons and compound-specific carbon stable isotopes of n-alkanes in the soil, irrigation water, and atmospheric deposition were analyzed. The analyses of hydrocarbon concentrations and geochemical characteristics reveal that the water is moderately contaminated by degraded heavy oil. According to the isotope analysis, inputs of modern C3 plants and degraded petroleum are present in the water, air, and soil. The similarities and dissimilarities among the water, air, and soil samples were determined by concentration, isotope, and multivariate statistical analyses. Hydrocarbons from various sources, as well as the water/atmospheric deposition samples, are more effectively differentiated through principal component analysis of carbon stable isotope ratios (δ(13)C) relative to hydrocarbon concentrations. Redundancy analysis indicates that 57.1 % of the variance in the δ(13)C of the soil can be explained by the δ(13)C of both the water and air, and 35.5 % of the variance in the hydrocarbon concentrations of the soil can be explained by hydrocarbon concentrations of both the water and the air. The δ(13)C in the atmospheric deposition accounts for 28.2 % of the δ(13)C variance in the soil, which is considerably higher than the variance in hydrocarbon concentrations of the soil explained by hydrocarbon concentrations of the atmospheric deposition (7.7 %). In contrast to δ(13)C analysis, the analysis of hydrocarbon concentrations underestimates the effect of petroleum contamination in the irrigated water and air on the surface soil. Overall, the irrigated water exerts a larger effect on the surface soil than does the atmospheric deposition.

  18. A multi-stable isotope framework to understand eutrophication in aquatic ecosystems. (United States)

    Gooddy, Daren C; Lapworth, Dan J; Bennett, Sarah A; Heaton, Tim H E; Williams, Peter J; Surridge, Ben W J


    Eutrophication is a globally significant challenge facing aquatic ecosystems, associated with human induced enrichment of these ecosystems with nitrogen (N) and phosphorus (P). However, the limited availability of inherent labels for P and N has constrained understanding of the triggers for eutrophication in natural ecosystems and appropriate targeting of management responses. This paper proposes and evaluates a new multi-stable isotope framework that offers inherent labels to track biogeochemical reactions governing both P and N in natural ecosystems. The framework couples highly novel analysis of the oxygen isotope composition of phosphate (δ(18)OPO4) with dual isotope analysis of oxygen and N within nitrate (δ(15)NNO3, δ(18)ONO3) and with stable N isotope analysis in ammonium (δ(15)NNH4). The River Beult in England is used as an exemplar system for initial evaluation of this framework. Our data demonstrate the potential to use stable isotope labels to track the input and downstream fate of nutrients from point sources, on the basis of isotopic differentiation for both P and N between river water and waste water treatment work effluent (mean difference = +1.7‰ for δ(18)OPO4; +15.5‰ for δ(15)NNH4 (under high flow); +7.3‰ for δ(18)ONO3 and +4.4‰ for δ(15)NNO3). Stable isotope data reveal nutrient inputs to the river upstream of the waste water treatment works that are consistent with partially denitrified sewage or livestock sources of nitrate (δ(15)NNO3 range = +11.5 to +13.1‰) and with agricultural sources of phosphate (δ(18)OPO4 range = +16.6 to +19.0‰). The importance of abiotic and metabolic processes for the in-river fate of N and P are also explored through the stable isotope framework. Microbial uptake of ammonium to meet metabolic demand for N is suggested by substantial enrichment of δ(15)NNH4 (by 10.2‰ over a 100 m reach) under summer low flow conditions. Whilst the concentration of both nitrate and phosphate

  19. Bird migration and avian influenza: a comparison of hydrogen stable isotopes and satellite tracking methods (United States)

    Bridge, Eli S.; Kelly, Jeffrey F.; Xiao, Xiangming; Takekawa, John Y.; Hill, Nichola J.; Yamage, Mat; Haque, Enam Ul; Islam, Mohammad Anwarul; Mundkur, Taej; Yavuz, Kiraz Erciyas; Leader, Paul; Leung, Connie Y.H.; Smith, Bena; Spragens, Kyle A.; Vandegrift, Kurt J.; Hosseini, Parviez R.; Saif, Samia; Mohsanin, Samiul; Mikolon, Andrea; Islam, Ausrafal; George, Acty; Sivananinthaperumal, Balachandran; Daszak, Peter; Newman, Scott H.


    Satellite-based tracking of migratory waterfowl is an important tool for understanding the potential role of wild birds in the long-distance transmission of highly pathogenic avian influenza. However, employing this technique on a continental scale is prohibitively expensive. This study explores the utility of stable isotope ratios in feathers in examining both the distances traveled by migratory birds and variation in migration behavior. We compared the satellite-derived movement data of 22 ducks from 8 species captured at wintering areas in Bangladesh, Turkey, and Hong Kong with deuterium ratios (δD) in the feathers of these and other individuals captured at the same locations. We derived likely molting locations from the satellite tracking data and generated expected isotope ratios based on an interpolated map of δD in rainwater. Although δD was correlated with the distance between wintering and molting locations, surprisingly, measured δD values were not correlated with either expected values or latitudes of molting sites. However, population-level parameters derived from the satellite-tracking data, such as mean distance between wintering and molting locations and variation in migration distance, were reflected by means and variation of the stable isotope values. Our findings call into question the relevance of the rainfall isotope map for Asia for linking feather isotopes to molting locations, and underscore the need for extensive ground truthing in the form of feather-based isoscapes. Nevertheless, stable isotopes from feathers could inform disease models by characterizing the degree to which regional breeding populations interact at common wintering locations. Feather isotopes also could aid in surveying wintering locations to determine where high-resolution tracking techniques (e.g. satellite tracking) could most effectively be employed. Moreover, intrinsic markers such as stable isotopes offer the only means of inferring movement information from

  20. Late Glacial Tropical Savannas in Sundaland Inferred From Stable Carbon Isotope Records of Cave Guano (United States)

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


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

  1. Interactions between surface waters in King George Island, Antarctica - a stable isotope perspective (United States)

    Perşoiu, Aurel; Bădăluşă, Carmen


    In this paper we present a first study of the isotopic composition of surface waters in the southern peninsulas (Barton, Fildes, Weaver and Potter) of King George Island, Antarctica. We have collected > 200 samples of snow and snowmelt, water (lake, river and spring), ice (glacier ice and permafrost) from the four peninsulas in February 2016 and analyzed them for their oxygen and hydrogen stable isotopic composition. Samples from lake water (50+) indicate a clear west-east depletion trend, suggesting a rain-out process as air masses are moving westward (and are progressively depleted in heavy isotopes) from their origin in the Drake Passage. In both Fildes and Barton Peninsulas, permafrost samples have the heaviest isotopic composition, most probably due to preferential incorporation of heavy isotopes in the ice during freezing (and no fractionation during melting). As permafrost melts, the resulting water mixes with isotopically lighter infiltrated snowmelt, and thus the groundwater has a lower isotopic composition. Further, lake and river (the later fed by lakes) water has the lightest isotopic composition, being derived mostly from the melting of light snow and glacier ice. It seems feasible to separate isotopically water in lakes/rivers (largely fed by melting multi-year glaciers and snow) and water from melting of snow/ground ice This preliminary study suggests that it is possible to separate various water sources in the southern peninsulas of King George Island, and this separation could be used to study permafrost degradation, as well as feeding and migration patterns in the bird fauna, with implications for protection purposes. Acknowledgments. The National Institute of Research and Development for Biological Sciences (Bucharest, Romania) and the Korean polar institute financially supported fieldwork in King George Island. We thank the personal at King Sejong (South Korea), Belingshaussen (Russia) and Carlini (Argentina) stations in King George Island for

  2. Stable carbon and oxygen isotope study on benthic foraminifera: Implication for microhabitat preferences and interspecies correlation (United States)

    Bhaumik, Ajoy K.; Kumar, Shiv; Ray, Shilpi; Vishwakarma, G. K.; Gupta, Anil K.; Kumar, Pushpendra; Sain, Kalachand


    Stable isotopes of benthic foraminifera have widely been applied in micropalaeontological research to understand vital effects in foraminifera. Isotopic fractionations are mainly controlled by ontogeny, bottom/pore water chemistry, habitat preference, kinetic effect and respiration. Discontinuous abundance of a species for isotopic analysis has forced us to select multiple species from down-core samples. Thus standardisation factors are required to convert isotopic values of one species with respect to other species. The present study is pursued on isotopic values of different pairs of benthic foraminifera from the Krishna-Godavari basin and Peru offshore to understand habitat-wise isotopic variation and estimation of isotopic correction factors for the paired species ( Cibicides wuellerstorfi-Bulimina marginata, Ammonia spp.- Loxostomum amygdalaeformis and Bolivina seminuda-Nonionella auris). Infaunal species ( B. marginata, Ammonia spp. and N. auris) show a lighter carbon isotopic excursion with respect to the epifaunal to shallow infaunal forms ( C. wuellerstorfi, L. amygdalaeformis and B. seminuda). These lighter δ^{13} C values are related to utilisation of CO2 produced by anaerobic remineralisation of organic matter. However, enrichment of δ^{18} O for the deeper microhabitat (bearing lower pH and decreased {CO3}^{2-}) is only recorded in case of B. marginata. It is reverse in case of N. auris and related to utilisation of respiratory CO2 and internal dissolve inorganic carbon pool. Estimation of interspecies isotopic correction factors for the species pairs (δ^{13} C of C. wuellerstorfi- B. marginata, L. amygdalaeformis- Ammonia spp., N. auris- B. seminuda) and δ^{18} O of C. wuellerstorfi- B. marginata are statistically reliable and may be used in palaeoecological studies.

  3. Using stable isotopes of nitrogen and carbon to study seabird ecology: applications in the Mediterranean seabird community

    Directory of Open Access Journals (Sweden)

    Manuela G. Forero


    Full Text Available The application of the stable isotope technique to ecological studies is becoming increasingly widespread. In the case of seabirds, stable isotopes of nitrogen and carbon have been mainly used as dietary tracers. This approach relieson the fact that food web isotopic signatures are reflected in the tissues of the consumer. In addition to the study of trophic ecology, stable isotopes have been used to track the movement of seabirds across isotopic gradients, as individuals moving between isotopically distinct foodwebs can carry with them information on the location of previous feeding areas. Studies applying the stable isotope methodology to the study of seabird ecology show a clear evolution from broad and descriptive approaches to detailed and individual-based analyses. The purpose of this article is to show the different fields of application of stable isotopes to the study of the seabird ecology. Finally, we illustrate the utility of this technique by considering the particularities of the Mediterranean seabird community, suggesting different ecological questions and conservation problems that could be addressed by using the stable isotope approach in this community.

  4. Stable sulfur and oxygen isotopes as geochemical tracers of sulfate in karst waters (United States)

    Sun, Jing; Kobayashi, Tatsuaki; Strosnider, William H. J.; Wu, Pan


    Karst water resources, which are extremely sensitive to mining activities, are critical for the support of human societies and ecological systems in many regions worldwide. In order to determine the sources and fate of dissolved sulfate in low-pH karst waters, hydrochemical variations of karst waters with and without acid mine drainage (AMD) impacts were investigated along with stable isotope dynamics. As expected, hydrochemical characteristics and isotopic compositions of the AMD and AMD-downstream water (ADW) were dramatically different from that of the non-AMD-impacted water (NAW). The sources of sulfur isotopes in sulfate were predominantly pyrite oxidation for the AMD and ADW, and atmospheric deposition for the NAW. Based on the general isotope-balance model, the relative proportions of sulfate oxygen derived from water and air were calculated. The mean proportion of sulfate oxygen derived from water in ADW was roughly double that of AMD. This suggests that the sulfate associated with AMD is predominantly influenced by aerobic pyrite oxidation, while that of ADW is likely affected by the dissolution of pyrite under anaerobic conditions in reservoir sediment. This observation was coincident with the noted variations of hydrochemical characteristics and was supported by principal component analysis. These results provide a better understanding of how stable isotopes of sulfate and water can be used to track mining contamination in karst aquifers, which could benefit remediation planning for these distinctive systems.

  5. Searching for the true diet of marine predators: incorporating Bayesian priors into stable isotope mixing models.

    Directory of Open Access Journals (Sweden)

    André Chiaradia

    Full Text Available Reconstructing the diet of top marine predators is of great significance in several key areas of applied ecology, requiring accurate estimation of their true diet. However, from conventional stomach content analysis to recent stable isotope and DNA analyses, no one method is bias or error free. Here, we evaluated the accuracy of recent methods to estimate the actual proportion of a controlled diet fed to a top-predator seabird, the Little penguin (Eudyptula minor. We combined published DNA data of penguins scats with blood plasma δ(15N and δ(13C values to reconstruct the diet of individual penguins fed experimentally. Mismatch between controlled (true ingested diet and dietary estimates obtained through the separately use of stable isotope and DNA data suggested some degree of differences in prey assimilation (stable isotope and digestion rates (DNA analysis. In contrast, combined posterior isotope mixing model with DNA Bayesian priors provided the closest match to the true diet. We provided the first evidence suggesting that the combined use of these complementary techniques may provide better estimates of the actual diet of top marine predators- a powerful tool in applied ecology in the search for the true consumed diet.

  6. Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake (United States)

    Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo


    Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

  7. Stable isotopes in plant physiology: using water isotopes to study water fluxes in a temperate forest (United States)

    Gerlein, C.; Wolf, A.; Caylor, K. K.


    Drought has profound consequences on vegetation, including decreases in instantaneous carbon uptake; damage that limits future uptake for the life of the plant; mortality that can lead to large sources of carbon to the atmosphere; and shifts in biogeography that alter future potential for carbon uptake and capacitance. These processes are largely absent from global models, for lack of understanding in how co-occurring plants compete for water, weak understanding of how plant hydraulics is coordinated to minimize risk of drought, and few empirical data to constrain superior models of these processes. Here we present the results of a large-scale field experiment at Silas Little Experimental Forest (NJ), where rainwater was diverted from a 10m^2 area around selected trees from two different species (either oak or pine trees) and either re-injected (control plots), discarded (drought plots) or replaced by isotopically labeled water (isotope plots). We sampled heavily the drought plots and collected valuable information on tree hydraulics under drought conditions, such as water potentials of soil, leaf and stem, photosynthetic rate or sap flow. At the isotope plots, we followed the injected water within the injection trees and the surrounding ones. In particular, using an innovative setup for in-situ measurement paired with a laser spectrometer, we studied the isotopes effects within the tree xylem, which gave us a better understanding of water uptake by the roots and its transport to the leaves. By tracking the labeled water in the surrounding trees, we were also able to quantify the importance of plant competition for water availability below ground. We show here the importance of understanding all the phases of the water transport in the biosphere to help constraining climate models.

  8. Stable isotope paleoaltimetry of Eocene core complexes in the North American Cordillera (United States)

    Mulch, A.; Teyssier, C.; Cosca, M. A.; Chamberlain, C. P.


    The hydrogen isotope composition of Eocene muscovite in mylonitic quartzite from the Kettle and Shuswap metamorphic core complexes (Washington and British Columbia) permits estimates of paleoaltimetry of the North American Cordillera at the onset of post-collisional lithospheric extension. Coupled oxygen, hydrogen, and 40Ar/39Ar isotope data indicate that meteoric water penetrated to significant depths during normal faulting along the Columbia River Detachment bounding both Kettle and Shuswap metamorphic core complexes. Synkinematic muscovite attains δDmuscovite values as low as -135‰ and -157‰, respectively, consistent with δDwater values of -115 ± 5‰ and -135 ± 5‰. In context with stable isotope data from Eocene sedimentary basins of continental North America, these data constrain the isotopic composition of precipitation from which paleoelevation estimates can be made. Stable isotope paleoaltimetry indicates that during detachment formation (49-47 Ma), orogen-parallel variations in topography existed, and mean elevations decreased from ≥4000 m at the latitude of the Shuswap core complex to ≥3000 m in the Kettle core complex. In addition, these data indicate a net decrease in mean surface elevation by ˜1000 m since the Eocene. Our results for the Kettle core complex are consistent with paleoelevation estimates based on fossil floral physiognomy in the Eocene Republic basin (Washington), indicating that high elevations characterized not only the frontal escarpment near the crustal-scale detachment but continued into the Okanogan highlands further west. Collectively, the stable isotope, geochronological, and paleofloral data support tectonic models of high Eocene surface elevations contemporaneous with magmatism and lithospheric extension.

  9. Fatty acid and stable carbon isotope characterization of Camelina sativa oil: implications for authentication. (United States)

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


    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.

  10. Reconstruction of trophic pathways between plankton and the North Iberian sardine (Sardina pilchardus using stable isotopes

    Directory of Open Access Journals (Sweden)

    Antonio Bode


    Full Text Available Feeding on phyto- and zooplankton by juvenile (< 1 year old and adult sardines (Sardina pilchardus was inferred from analyses of natural abundance of stable carbon and nitrogen isotopes in samples from the northwestern Iberian Peninsula (Spain collected at the beginning of the upwelling season and peak spawning period of sardine. Plankton samples were fractionated through nets of 20, 200, 500, 1000 and 2000 ?m mesh-size and the muscle protein of individual sardines was isolated before isotopic determinations. Up to six planktonic components and two sardine feeding types were identified from the modes in the frequency distributions of isotope abundance values. Also, the most probable pathways for carbon and nitrogen flows between compartments were analysed. The resulting food web revealed a relatively large degree of omnivory, both in plankton and sardine components, which confirms that complex trophic interactions could also occur in pelagic upwelling ecosystems. Young sardines had isotope abundance values clustered around a single mode in the frequency distribution, while adult sardines displayed two main modes. These modes are interpreted as representative of two extreme feeding types: one related to the individual capture of zooplankton prey and the other to unselective filter-feeding. Although both types of feeding could include micro- (20-200 ?m and mesozooplankton (200-2000 ?m prey, phytoplankton appears to be ingested mainly by filter-feeding. However, even adult sardines must be mainly zoophagous to achieve the observed isotopic abundance values, taking into account current assumptions on stable isotope enrichment through trophic levels. From the differences in the resulting pathways using either carbon or nitrogen isotopes, we interpreted that sardines acquire most of the protein nitrogen from zooplankton while a substantial fraction of their carbon would derive from phytoplankton. These interpretations agree with the information

  11. From the ground up: global nitrous oxide sources are constrained by stable isotope values.

    Directory of Open Access Journals (Sweden)

    David M Snider

    Full Text Available Rising concentrations of nitrous oxide (N2O in the atmosphere are causing widespread concern because this trace gas plays a key role in the destruction of stratospheric ozone and it is a strong greenhouse gas. The successful mitigation of N2O emissions requires a solid understanding of the relative importance of all N2O sources and sinks. Stable isotope ratio measurements (δ15N-N2O and δ18O-N2O, including the intramolecular distribution of 15N (site preference, are one way to track different sources if they are isotopically distinct. 'Top-down' isotope mass-balance studies have had limited success balancing the global N2O budget thus far because the isotopic signatures of soil, freshwater, and marine sources are poorly constrained and a comprehensive analysis of global N2O stable isotope measurements has not been done. Here we used a robust analysis of all available in situ measurements to define key global N2O sources. We showed that the marine source is isotopically distinct from soil and freshwater N2O (the continental source. Further, the global average source (sum of all natural and anthropogenic sources is largely controlled by soils and freshwaters. These findings substantiate past modelling studies that relied on several assumptions about the global N2O cycle. Finally, a two-box-model and a Bayesian isotope mixing model revealed marine and continental N2O sources have relative contributions of 24-26% and 74-76% to the total, respectively. Further, the Bayesian modeling exercise indicated the N2O flux from freshwaters may be much larger than currently thought.

  12. Study on the Effect of the Separating Unit Optimization on the Economy of Stable Isotope Separation

    Directory of Open Access Journals (Sweden)

    YANG Kun


    Full Text Available An economic criterion called as yearly net profit of single separating unit (YNPSSU was presented to evaluate the influence of structure optimization on the economy. Using YNPSSU as a criterion, economic analysis was carried out for the structure optimization of separating unit in the case of separating SiF4 to obtain the 28Si and 29Si isotope. YNPSSU was calculated and compared with that before optimization. The results showed that YNPSSU was increased by 12.3% by the structure optimization. Therefore, the structure optimization could increase the economy of the stable isotope separation effectively.

  13. Eddy Covariance measurements of stable isotopes (δD and δ18O) in water vapor (United States)

    Braden-Behrens, Jelka; Knohl, Alexander


    Stable isotopes are a promising tool to enhance our understanding of ecosystem gas exchanges. Studying 18O and 2H in water vapour (H2Ov) can e.g. help partitioning evapotranspiration into its components. With recent developments in laser spectroscopy direct Eddy Covariance (EC) measurements for investigating fluxes of stable isotopologues became feasible. So far very few case studies have applied the EC method to measure stable isotopes in water vapor. We continuously measure fluxes of water vapor isotopologues with the EC method in a managed beech forest in Thuringia, Germany, since autumn 2015 using the following setup: An off-axis integrated cavity output water vapor isotope analyzer (WVIA, Los Gatos Research. Inc, USA) measures the water vapour concentration and its isotopic composition (δD and δ18O). The instrument, that was optimized for high flow rates (app. 4slpm) to generate high frequency (2Hz) measurements, showed sufficient precision with Allan Deviations of app. 0.12 ‰ for δD and 0.06 ‰ for δ18O for averaging periods of 100s. The instrument was calibrated hourly using a high-flow optimized version of the water vapor isotope standard source (WVISS, Los Gatos Research. Inc, USA) that provides water vapor with known isotopic composition for a large range of different concentrations. Our calibration scheme includes a near continuous concentration range calibration instead of a simple 2 or 3-point calibration to face the analyzers strong concentration dependency within a range of app. 6 000 to 16 000 ppm in winter and app. 8 000 to 23 000 ppm in summer. In the used setup, the high-flow and high-frequency optimized water vapor isotope analyzer (WVIA) showed suitable characteristics (Allan deviation and spectral energy distribution) to perform Eddy covariance measurements of stable isotopes in H2Ov. Thus, this novel instrument for EC measurements of water vapor isotopologues provides a new opportunity for studying the hydrological cycle in long

  14. Population and individual foraging patterns of two hammerhead sharks using carbon and nitrogen stable isotopes. (United States)

    Loor-Andrade, P; Galván-Magaña, F; Elorriaga-Verplancken, F R; Polo-Silva, C; Delgado-Huertas, A


    Individual foraging behavior is an important variable of predators commonly studied at the population level. Some hammerhead shark species play a significant role in the marine ecosystem as top consumers. In this context, stable isotope analysis allows us to infer some ecological metrics and patterns that cannot usually be obtained using traditional methods. We determined the isotopic composition (δ(13)C and δ(15)N values) of dorsal muscle and vertebrae of Sphyrna lewini and Sphyrna zygaena using a continuous-flow system consisting of an elemental analyzer combined with a Delta Plus XL mass spectrometer. Foraging variability by sex and by individual was inferred from the isotopic values. There were no significant differences in the isotopic values of muscle samples between sexes, but there were differences between species. The trophic niche breadth of the two species was similar and overlap was low. A low niche overlap was observed between S. lewini individual vertebrae. We found differences in the δ(15)N values of S. zygaena vertebrae, with lower values in the first group of samples. Despite these hammerhead shark species inhabiting the same area, there was low trophic niche overlap between species and individuals, due to different individual foraging strategies, according to the carbon and nitrogen isotopic profiles obtained. The use of tissues that retain lifetime isotopic information is useful to complement studies on trophic ecology. Copyright © 2015 John Wiley & Sons, Ltd.

  15. Insights into Ancient Human Populations and their Environment through Stable Isotope Analysis (United States)

    Macko, S. A.


    Fundamental to the understanding of human history is the ability to make interpretations based on artifacts and other remains which are used to gather information about an ancient population. Sequestered in the organic matrices of these remains can be information concerning incidence of disease, population interactions, genetic defects and diet. Stable isotopes have long been used to interpret diet and trophic interactions in modern ecosystems. We suggest that the isotope compositions of a commonly overlooked material, human hair, is an ideal tool to be used in gleaning information, especially on human diets, about ancient civilizations. Hair can be well-preserved and is amenable to routine measurements of 13C, 15N and 34S isotope analyses and distinguishing sources of nutrition. We have isotopically characterized hair from both modern and ancient individuals. There is a wide diversity in isotope values owing, at least partially, to the levels of seafood, corn-fed animals and other grains in diet. Using these isotope tracers, new information regarding historical figures (George Washington, 1799 AD) to perhaps the most ancient of mummies, the Chinchorro of Chile (more than 7000 BP) as well as the Moche of Peru (1500 BP) and the best preserved mummy, the Neolithic Ice Man of the Oetztaler Alps (5200 BP), have been deciphered. It appears that the often-overlooked hair in archaeological sites represents a significant approach for understanding ancient human communities and their environments, as well as new perspectives on our use of our own modern nutritional sources.

  16. Marine bivalve feeding strategy, radiocarbon ages and stable isotopes in Scottish coastal waters (United States)

    Lo Giudice Cappelli, Elena; Austin, William


    Marine bivalve molluscs have been widely used for palaeoenvironmental reconstructions as their carbonate provides a direct chronology of environmental change through radiocarbon dating, and their shell composition, particularly with regard to their oxygen and carbon stable isotopes, is likely to reflect ambient seawater conditions. However, stable isotope signatures of marine bivalve shells are difficult to interpret, as shell formation can be influenced by secondary factors such as metabolic processes and feeding strategies. In radiocarbon ages, uncertainty is introduced as bivalves inhabit a range of ecological niches which may be of significance in the case of deep borrowing and deposit feeding bivalves, as they could incorporate older carbon in their shells, resulting in apparent older ages than the true age of the dissolved inorganic carbon in the overlying seawater. To discriminate between the different factors influencing the composition of marine molluscs' shells, we measured radiocarbon ages, oxygen and carbon stable isotopes in nine species of marine bivalves having different known feeding strategies and inhabiting a number of ecological niches; all shells being live-collected (between 1923-1925) from six localities around the Scottish coast, a wider context than has been previously undertaken. Our results show that in situ variability (i.e.: replicate measurements of the same species at the same location) is generally low for both stable isotope analyses and radiocarbon dates, indicating good accuracy of the measurements. Intra-species (i.e.: same species - different location) and inter-species (i.e.: different species - same location) variability is significant in stable isotopes measurements, meaning that marine bivalve shells do record changes in the local environment and are sensitive to different feeding strategies and ecological settings. In contrast, radiocarbon ages do not change with location and are not sensitive to molluscs' diets or

  17. High-resolution stable isotope signature of a land-falling atmospheric river in Southern Norway (United States)

    Weng, Yongbiao; Sodemann, Harald


    Gathering observational evidence of the long-range moisture versus local source contributions remains a scientific challenge, but is critical for understanding how hydrological extremes develop. Moisture transport to the west coast of Norway is often connected to elongated meridional structures of high water vapour flux known as Atmospheric Rivers. It is still an open question how well moisture sources estimated by different numerical models for such events of long-range transport correspond with reality. In this study, we present high resolution stable isotope information collected during a land-falling Atmospheric River in Southern Norway during winter 2016, and analyse the data with the aim to differentiate between moisture source signatures and below-cloud processes affecting the stable isotope composition. The precipitation characterised by a pronounced warm front was sampled manually on a rooftop platform at a 10-20 minute interval during the 24h of the event and later measured by a laser spectrometer (Picarro L2140-i) in the lab for δ18O, δD, and d-excess. Simultaneously, the stable isotope composition of water vapor was continuously measured at high resolution. To that end, ambient air was continuously pumped from a nearby inlet at 25 m above the ground and measured by another laser spectrometer (Picarro L2130-i). Stable water isotope measurements were supplemented by detailed precipitation parameters from a laser disdrometer (OTT Parsivel2), Micro Rain Radar (MRR-2), Total Precipitation Sensor (TPS-3100), and a nearby weather station. Measurements show a signature of two depletion periods in the main stable isotope parameters that are not apparent in precipitation amount and atmospheric temperature measurements. The deuterium excess in rainfall responds differently, with first and increase and then a decrease during these depletion periods. We interpret this as a combined consequence of airmass change, cloud microphysics, and below-cloud effects

  18. Non-biological fractionation of stable Ca isotopes in soils of the Atacama Desert, Chile (United States)

    Ewing, Stephanie A.; Yang, Wenbo; DePaolo, Donald J.; Michalski, Greg; Kendall, Carol; Stewart, Brian W.; Thiemens, Mark; Amundson, Ronald


    We measured Ca stable isotope ratios (δ 44/40Ca) in an ancient (2 My), hyperarid soil where the primary source of mobile Ca is atmospheric deposition. Most of the Ca in the upper meter of this soil (3.5 kmol m -2) is present as sulfates (2.5 kmol m -2), and to a lesser extent carbonates (0.4 kmol m -2). In aqueous extracts of variably hydrated calcium sulfate minerals, δ 44/40Ca E values (vs. bulk Earth) increase with depth (1.4 m) from a minimum of -1.91‰ to a maximum of +0.59‰. The trend in carbonate-δ 44/40Ca in the top six horizons resembles that of sulfate-δ 44/40Ca, but with values 0.1-0.6‰ higher. The range of observed Ca isotope values in this soil is about half that of δ 44/40Ca values observed on Earth. Linear correlation among δ 44/40Ca, δ 34S and δ 18O values indicates either (a) a simultaneous change in atmospheric input values for all three elements over time, or (b) isotopic fractionation of all three elements during downward transport. We present evidence that the latter is the primary cause of the isotopic variation that we observe. Sulfate-δ 34S values are positively correlated with sulfate-δ 18O values ( R2 = 0.78) and negatively correlated with sulfate δ 44/40Ca E values ( R2 = 0.70). If constant fractionation and conservation of mass with downward transport are assumed, these relationships indicate a δ 44/40Ca fractionation factor of -0.4‰ in CaSO 4. The overall depth trend in Ca isotopes is reproduced by a model of isotopic fractionation during downward Ca transport that considers small and infrequent but regularly recurring rainfall events. Near surface low Ca isotope values are reproduced by a Rayleigh model derived from measured Ca concentrations and the Ca fractionation factor predicted by the relationship with S isotopes. This indicates that the primary mechanism of stable isotope fractionation in CaSO 4 is incremental and effectively irreversible removal of an isotopically enriched dissolved phase by downward

  19. Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment (United States)

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


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

  20. Linking cases of illegal shootings of the endangered California condor using stable lead isotope analysis

    Energy Technology Data Exchange (ETDEWEB)

    Finkelstein, Myra E., E-mail: [Microbiology and Environmental Toxicology Department, University of California, Santa Cruz, CA 95064 (United States); Kuspa, Zeka E. [Microbiology and Environmental Toxicology Department, University of California, Santa Cruz, CA 95064 (United States); Welch, Alacia [National Park Service, Pinnacles National Park, 5000 Highway 146, Paicines, CA 95043 (United States); Eng, Curtis; Clark, Michael [Los Angeles Zoo and Botanical Gardens, 5333 Zoo Drive, Los Angeles, CA 90027 (United States); Burnett, Joseph [Ventana Wildlife Society, 19045 Portola Dr. Ste. F-1, Salinas, CA 93908 (United States); Smith, Donald R. [Microbiology and Environmental Toxicology Department, University of California, Santa Cruz, CA 95064 (United States)


    Lead poisoning is preventing the recovery of the critically endangered California condor (Gymnogyps californianus) and lead isotope analyses have demonstrated that ingestion of spent lead ammunition is the principal source of lead poisoning in condors. Over an 8 month period in 2009, three lead-poisoned condors were independently presented with birdshot embedded in their tissues, evidencing they had been shot. No information connecting these illegal shooting events existed and the timing of the shooting(s) was unknown. Using lead concentration and stable lead isotope analyses of feathers, blood, and recovered birdshot, we observed that: i) lead isotope ratios of embedded shot from all three birds were measurably indistinguishable from each other, suggesting a common source; ii) lead exposure histories re-constructed from feather analysis suggested that the shooting(s) occurred within the same timeframe; and iii) two of the three condors were lead poisoned from a lead source isotopically indistinguishable from the embedded birdshot, implicating ingestion of this type of birdshot as the source of poisoning. One of the condors was subsequently lead poisoned the following year from ingestion of a lead buckshot (blood lead 556 µg/dL), illustrating that ingested shot possess a substantially greater lead poisoning risk compared to embedded shot retained in tissue (blood lead ∼20 µg/dL). To our knowledge, this is the first study to use lead isotopes as a tool to retrospectively link wildlife shooting events. - Highlights: • We conducted a case-based analysis of illegal shootings of California condors. • Blood and feather Pb isotopes were used to reconstruct the illegal shooting events. • Embedded birdshot from the three condors had the same Pb isotope ratios. • Feather and blood Pb isotopes indicated that the condors were shot in a common event. • Ingested shot causes substantially greater lead exposure compared to embedded shot.

  1. Cumulative yields of stable and long-lived isotopes of tin in neutron-induced fission

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, K.J.R.; DeLaeter, J.R. (Western Australian Inst. of Tech., South Bentley); Boldeman, J.W. (Australian Atomic Energy Commission Research Establishment, Lucas Heights. Physics Div.); Thode, H.G. (McMaster Univ., Hamilton, Ontario (Canada). Dept. of Chemistry)


    The relative cumulative fission yields of the six stable isotopes of tin (sup(117)Sn, sup(118)Sn, sup(119)Sn, sup(120)Sn, sup(122)Sn, and sup(124)Sn) and the long-lived isotope sup(126)Sn have been measured in the thermal and epicadmium neutron fission of sup(233)U and sup(235)U, and the epicadmium neutron fission of sup(238)U. Nanogram-sized fission product tin samples were extracted from irradiated uranium samples and analyzed in a solid source mass spectrometer. In each case a smooth curve can be drawn through the yield points of the seven isotopes of tin. There is, therefore, no evidence of fine structure in the 117 < = A < = 126 portion of the symmetric mass region.

  2. Using stable isotope analyses to identify allochthonous inputs to Lake Naivasha mediated via the hippopotamus gut. (United States)

    Grey, J; Harper, D M


    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 tested at Lake Naivasha, Kenya. Hippopotami proved faithful to a short grass diet although supplementary grazing of aquatic macrophytes was observed. The typical isotopic ratios of C4 grasses ingested were not altered substantially by gut processes, and were clearly distinct from algal and aquatic macrophyte isotopic ratios. However, marginal plants such as Cyperus papyrus exhibit C4 ratios, and so the technique is suitable only for use in localities where 'contamination' from such sources is negligible.

  3. Stable isotope evidence for shifting Mediterranean climatic influences in Western Romania, East-Central Europe (United States)

    Perşoiu, Aurel; Viorica, Nagavciuc; Carmen, Bădăluţă


    The stable isotopic composition of oxygen and hydrogen in precipitation, preserved in various sedimentary archives (speleothems, cave ice, tree rings) is being intensively used to reconstruct past climatic variability in western Romania. These studies heavily rely on the assumption that air temperature is the main factor controlling the isotopic composition of precipitation and hence this climatic parameter is the one reconstructed. However, ongoing monitoring studies are increasingly showing that this, especially along Romania's western border, moisture source is playing an important role in determining the isotopic composition of precipitation, hence complicating the simplistic picture outlined above. One of the main factors influencing climate variability in Romania is the North Atlantic Oscillation (NAO), a measure of the strength of the Icelandic Low and Azores High. Over During the positive NAO phase, the Atlantic storms are displaced northward and, although reduced in strength, Mediterranean cyclones penetrate further north. During the negative phase however, the Atlantic storms track is displaced southward, restricting the area receiving Mediterranean precipitation to the SW corner of Romania. Here we present isotopic evidence for a shift in the source of precipitation from North Atlantic to Mediterranean ones in SW Romania that masks the temperature signal recorded in the stable isotopic composition of precipitation. Between April 2012 and 2014 we have collected monthly samples of precipitation along a N-S transect in Western Romania and have analyzed them for their δ18O and δ2H. Precipitation in NW Romania are derived solely from North Atlantic sources, while those in SW Romania mix moisture evaporated from both the North Atlantic and the Mediterranean Sea. The northern boundary of the Mediterranean influence is shifting in phase with the NAO index and the position of the jet-stream. As a result, during periods with high NAO index, the stable isotope

  4. Surface oceanographic fronts influencing deep-sea biological activity: Using fish stable isotopes as ecological tracers (United States)

    Louzao, Maite; Navarro, Joan; Delgado-Huertas, Antonio; de Sola, Luis Gil; Forero, Manuela G.


    Ecotones can be described as transition zones between neighbouring ecological systems that can be shaped by environmental gradients over a range of space and time scales. In the marine environment, the detection of ecotones is complex given the highly dynamic nature of marine systems and the paucity of empirical data over ocean-basin scales. One approach to overcome these limitations is to use stable isotopes from animal tissues since they can track spatial oceanographic variability across marine systems and, in turn, can be used as ecological tracers. Here, we analysed stable isotopes of deep-sea fishes to assess the presence of ecological discontinuities across the western Mediterranean. We were specifically interested in exploring the connection between deep-sea biological activity and particular oceanographic features (i.e., surface fronts) occurring in the pelagic domain. We collected samples for three different abundant deep-sea species in May 2004 from an experimental oceanographic trawling cruise (MEDITS): the Mictophydae jewel lanternfish Lampanyctus crocodilus and two species of the Gadidae family, the silvery pout Gadiculus argenteus and the blue whiting Micromesistius poutassou. The experimental survey occurred along the Iberian continental shelf and the upper and middle slopes, from the Strait of Gibraltar in the SW to the Cape Creus in the NE. The three deep-sea species were highly abundant throughout the study area and they showed geographic variation in their isotopic values, with decreasing values from north to south disrupted by an important change point around the Vera Gulf. Isotopic latitudinal gradients were explained by pelagic oceanographic conditions along the study area and confirm the existence of an ecotone at the Vera Gulf. This area could be considered as an oceanographic boundary where waters of Atlantic origin meet Mediterranean surface waters forming important frontal structures such as the Almeria-Oran front. In fact, our results

  5. Stable lead isotopic analyses of historic and contemporary lead contamination of San Francisco Bay estuary (United States)

    Ritson, P.I.; Bouse, R.M.; Flegal, A.R.; Luoma, S.N.


    Variations in stable lead isotopic composition (240Pb, 206Pb, 207Pb, 208Pb) in three sediment cores from the San Francisco Bay estuary document temporal changes in sources of lead during the past two centuries. Sediment, with lead from natural geologic sources, and relatively homogeneous lead isotopic compositions are overlain by sediments whose isotopic compositions indicate change in the sources of lead associated with anthropogenic modification of the estuary. The first perturbations of lead isotopic composition in the cores occur in the late 1800s concordant with the beginning of industrialization around the estuary. Large isotopic shifts, toward lower 206Pb/207Pb, occur after the turn of the century in both Richardson and San Pablo Bays. A similar relationship among lead isotopic compositions and lead concentrations in both Bays suggest contamination from the same source (a lead smelter). The uppermost sediments (post 1980) of all cores also have a relatively homogenous lead isotopic composition distinct from pre-anthropogenic and recent aerosol signatures. Lead isotopic compositions of leachates from fourteen surface sediments and five marsh samples from the estuary were also analyzed. These analyses suggest that the lead isotopic signature identified in the upper horizons of the cores is spatially homogeneous among recently deposited sediments throughout the estuary. Current aerosol lead isotopic compositions [Smith, D.R., Niemeyer, S., Flegal, A.R., 1992. Lead sources to California sea otters: industrial inputs circumvent natural lead biodepletion mechanisms. Environmental Research 57, 163-175] are distinct from the isotopic compositions of the surface sediments, suggesting that the major source of lead is cycling of historically contaminated sediments back through the water column. Both the upper core sediments and surface sediments apparently derive their lead predominantly from sources internal to the estuary. These results support the idea that

  6. Stable isotopic composition of perchlorate and nitrate accumulated in plants: Hydroponic experiments and field data (United States)

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


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

  7. A versatile method for stable carbon isotope analysis of carbohydrates by high-performance liquid chromatography/isotope ratio mass spectrometry

    NARCIS (Netherlands)

    Boschker, H.T.S.; Moerdijk-Poortvliet, T.C.W.; Van Breugel, P.; Houtekamer, M.J.; Middelburg, J.J.


    We have developed a method to analyze stable carbon isotope (13C/12C) ratios in a variety of carbohydrates using high-performance liquid chromatography/isotope ratio mass spectrometry (HPLC/IRMS). The chromatography is based on strong anion-exchange columns with low strength NaOH eluents. An eluent

  8. Geographical Tracing of the West Lake Longjing Tea Based on the Stable Isotope Ratios

    Directory of Open Access Journals (Sweden)

    WANG Jie;SHI Yuan-zhi;ZHANG Qun-feng;NI Kang;YI Xiao-yun;MA Li-feng;RUAN Jian-yun


    Full Text Available The West Lake Longjing tea is a famous specialty with long history in Zhengjiang province and its price is higher than any other flatten-shaped tea. However, traders tend to sell counterfeit West Lake Longjing tea in the market to acquire higher economic values. Otherwise, plants from different geographical locations have distinct isotope ratio, which form the element fingerprints due to the variation of climate and soil properties. Thus, it is necessary to do the geographical tracing of the West Lake Longjing tea based on the stable isotope ratios. In this study, we collected the flatten-shaped tea samples from the Hangzhou, Shaoxing and Lishui of Zhejiang, Qingchuan of Sichuan, Liping of Guizhou and Rizhao of Shandong where the flatten-shaped tea were widely produced. And the stable isotope ratios (C, H, O, N, Cd, Pb, Sr in the flatten-shaped tea samples were also assayed. Differences of the stable isotope ratios in the flatten-shaped tea from different producing areas were obtained by the variance analysis. The comparision of the stable isotope ratio values of West Lake Longjing tea and other flatten-shaped tea producing from different areas were completed. Fisher linear discriminant analysis (FLDA, decision tree and back propagation artificial neural network (BP-ANN were used to establish the origin recognition model. The stable isotope ratios in flatten-shaped tea produced from different areas showed the difference followed with the different producing areas. For the δD and δ18O in samples, maybe influenced by the land effect and the elevation effect; a positive correlation was found between δD and δ18O; The ratio of 88Sr/86Sr was increased following the latitude’s increasing of the four provinces. Compared the recognition ability among those models of FLDA, decision tree and BP-ANN, all the recognition ability were above 76%. As applied by external validation samples, decision tree model was suitable for geographical origin

  9. Source tracing of natural organic matter bound mercury in boreal forest runoff with mercury stable isotopes. (United States)

    Jiskra, Martin; Wiederhold, Jan G; Skyllberg, Ulf; Kronberg, Rose-Marie; Kretzschmar, Ruben


    Terrestrial runoff represents a major source of mercury (Hg) to aquatic ecosystems. In boreal forest catchments, such as the one in northern Sweden studied here, mercury bound to natural organic matter (NOM) represents a large fraction of mercury in the runoff. We present a method to measure Hg stable isotope signatures of colloidal Hg, mainly complexed by high molecular weight or colloidal natural organic matter (NOM) in natural waters based on pre-enrichment by ultrafiltration, followed by freeze-drying and combustion. We report that Hg associated with high molecular weight NOM in the boreal forest runoff has very similar Hg isotope signatures as compared to the organic soil horizons of the catchment area. The mass-independent fractionation (MIF) signatures (Δ 199 Hg and Δ 200 Hg) measured in soils and runoff were in agreement with typical values reported for atmospheric gaseous elemental mercury (Hg 0 ) and distinctly different from reported Hg isotope signatures in precipitation. We therefore suggest that most Hg in the boreal terrestrial ecosystem originated from the deposition of Hg 0 through foliar uptake rather than precipitation. Using a mixing model we calculated the contribution of soil horizons to the Hg in the runoff. At moderate to high flow runoff conditions, that prevailed during sampling, the uppermost part of the organic horizon (Oe/He) contributed 50-70% of the Hg in the runoff, while the underlying more humified organic Oa/Ha and the mineral soil horizons displayed a lower mobility of Hg. The good agreement of the Hg isotope results with other source tracing approaches using radiocarbon signatures and Hg : C ratios provides additional support for the strong coupling between Hg and NOM. The exploratory results from this study illustrate the potential of Hg stable isotopes to trace the source of Hg from atmospheric deposition through the terrestrial ecosystem to soil runoff, and provide a basis for more in-depth studies investigating the

  10. Local vs. Regional Groundwater Flow Delineation from Stable Isotopes at Western North America Springs. (United States)

    Springer, Abraham E; Boldt, Elizabeth M; Junghans, Katie M


    The recharge location for many springs is unknown because they can be sourced from proximal, shallow, atmospheric sources or long-traveled, deep, regional aquifers. The stable isotope (18 O and 2 H) geochemistry of springs water can provide cost-effective indications of relative flow path distance without the expense of drilling boreholes, conducting geophysical studies, or building groundwater flow models. Locally sourced springs generally have an isotopic signature similar to local precipitation for that region and elevation. Springs with a very different isotopic composition than local meteoric inputs likely have non-local recharge, representing a regional source. We tested this local vs. regional flow derived hypothesis with data from a new, large springs isotopic database from studies across Western North America in Arizona, Nevada, and Alberta. The combination of location-specific precipitation data with stable isotopic groundwater data provides an effective method for flow path determination at springs. We found springs in Arizona issue from a mix of regional and local recharge sources. These springs have a weak elevation trend across 1588 m of elevation where higher elevation springs are only slightly more depleted than low elevation springs with a δ18 O variation of 5.9‰. Springs sampled in Nevada showed a strong elevation-isotope relationship with high-elevation sites discharging depleted waters and lower elevation springs issuing enriched waters; only a 2.6‰ difference exists in 18 O values over an elevation range of more than 1500 m. Alberta's springs are mostly sourced from local flow systems and show a moderate elevation trend of 1200 m, but the largest range in δ18 O, 7.1‰. © 2016, National Ground Water Association.

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

    Directory of Open Access Journals (Sweden)

    Luciano O Valenzuela

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

  12. Dietary heterogeneity among Western industrialized countries reflected in the stable isotope ratios of human hair. (United States)

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


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

  13. Integration of stable isotope and trace contaminant concentration for enhanced forensic acetone discrimination. (United States)

    Moran, James J; Ehrhardt, Christopher J; Wahl, Jon H; Kreuzer, Helen W; Wahl, Karen L


    We analyzed 21 neat acetone samples from 15 different suppliers to demonstrate the utility of a coupled stable isotope and trace contaminant strategy for distinguishing forensically-relevant samples. By combining these two pieces of orthogonal data we could discriminate all of the acetones that were produced by the 15 different suppliers. Using stable isotope ratios alone, we were able to distinguish 8 acetone samples, while the remaining 13 fell into four clusters with highly similar signatures. Adding trace chemical contaminant information enhanced discrimination to 13 individual acetones with three residual clusters. The acetones within each cluster shared a common manufacturer and might, therefore, not be expected to be resolved. The data presented here demonstrates the power of combining orthogonal data sets to enhance sample fingerprinting and highlights the role disparate data could play in future forensic investigations. © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Stable Isotope Labeling in Zebrafish Allows in Vivo Monitoring of Cardiac Morphogenesis* (United States)

    Konzer, Anne; Ruhs, Aaron; Braun, Helene; Jungblut, Benno; Braun, Thomas; Krüger, Marcus


    Quantitative proteomics is an important tool to study biological processes, but so far it has been challenging to apply to zebrafish. Here, we describe a large scale quantitative analysis of the zebrafish proteome using a combination of stable isotope labeling and liquid chromatography-mass spectrometry (LC-MS). Proteins derived from the fully labeled fish were used as a standard to quantify changes during embryonic heart development. LC-MS-assisted analysis of the proteome of activated leukocyte cell adhesion molecule zebrafish morphants revealed a down-regulation of components of the network required for cell adhesion and maintenance of cell shape as well as secondary changes due to arrest of cellular differentiation. Quantitative proteomics in zebrafish using the stable isotope-labeling technique provides an unprecedented resource to study developmental processes in zebrafish. PMID:23412571

  15. Stable isotope labeling in zebrafish allows in vivo monitoring of cardiac morphogenesis. (United States)

    Konzer, Anne; Ruhs, Aaron; Braun, Helene; Jungblut, Benno; Braun, Thomas; Krüger, Marcus


    Quantitative proteomics is an important tool to study biological processes, but so far it has been challenging to apply to zebrafish. Here, we describe a large scale quantitative analysis of the zebrafish proteome using a combination of stable isotope labeling and liquid chromatography-mass spectrometry (LC-MS). Proteins derived from the fully labeled fish were used as a standard to quantify changes during embryonic heart development. LC-MS-assisted analysis of the proteome of activated leukocyte cell adhesion molecule zebrafish morphants revealed a down-regulation of components of the network required for cell adhesion and maintenance of cell shape as well as secondary changes due to arrest of cellular differentiation. Quantitative proteomics in zebrafish using the stable isotope-labeling technique provides an unprecedented resource to study developmental processes in zebrafish.

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

    DEFF Research Database (Denmark)

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


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

  17. Astronaut Bones: Stable Calcium Isotopes in Urine as a Biomarker of Bone Mineral Balance (United States)

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


    Bone loss is a common health concern, in conditions ranging from osteoporosis to cancer. Bone loss due to unloading is also an important health issue for astronauts. We demonstrate stable calcium isotopes, a tool developed in geochemistry, are capable of detecting real-time quantitative changes in net bone mineral balance (BMB) using serum and urine [1]. We validated this technique by comparing with DEXA and biomarker data in subjects during bed rest, a ground-based analog of space flight effects [2-4]. We now apply this tool to assess changes in astronauts' BMB before, during and after 4-6 month space missions. There is stable isotope fractionation asymmetry between bone formation and resorption. During bone formation there is a mass-dependent preference for "lighter" calcium isotopes to be removed from serum and incorporated into bone mineral. During bone resorption, there is no measurable isotopic discrimination between serum and bone. Hence, when bone formation rates exceed that of resorption, serum and urine become isotopically "heavy" due to the sequestration of "light" calcium in bone. Conversely, when bone resorption exceeds bone formation, serum and urine become isotopically "light" due to the release of the sequestered light calcium from bone. We measured Ca isotopes in urine of thirty International Space Station astronauts. Average Ca isotope values in astronauts' urine shift isotopically lighter during microgravity, consistent with negative net BMB. Within a month of return to Earth, astronauts returned to within error of their δ44Ca value prior to departure. Urine samples from astronauts testing bone loss countermeasures showed bisphosphonates provide a viable pharmacological countermeasure. Some, but not all, individuals appear able to resist bone loss through diet and intensive resistive exercise alone. This is a promising new technique for monitoring BMB in astronauts, and hopefully someday on the way to/from Mars, this also has important clinical

  18. Understanding trophic interactions in host-parasite associations using stable isotopes of carbon and nitrogen. (United States)

    Nachev, Milen; Jochmann, Maik A; Walter, Friederike; Wolbert, J Benjamin; Schulte, S Marcel; Schmidt, Torsten C; Sures, Bernd


    Stable isotope analysis of carbon and nitrogen can deliver insights into trophic interactions between organisms. While many studies on free-living organisms are available, the number of those focusing on trophic interactions between hosts and their associated parasites still remains scarce. In some cases information about taxa (e.g. acanthocephalans) is completely missing. Additionally, available data revealed different and occasionally contrasting patterns, depending on the parasite's taxonomic position and its degree of development, which is most probably determined by its feeding strategy (absorption of nutrients through the tegument versus active feeding) and its localization in the host. Using stable isotope analysis of carbon and nitrogen we provided first data on the trophic position of an acanthocephalan species with respect to its fish host. Barbels (Barbus barbus) infected only with adult acanthocephalans Pomphorhynchus laevis as well as fish co-infected with the larval (L4) nematodes Eustrongylides sp. from host body cavity were investigated in order to determine the factors shaping host-parasite trophic interactions. Fish were collected in different seasons, to study also potential isotopic shifts over time, whereas barbels with single infection were obtained in summer and co-infected ones in autumn. Acanthocephalans as absorptive feeders showed lower isotope discrimination values of δ (15)N than the fish host. Results obtained for the acanthocephalans were in line with other parasitic taxa (e.g. cestodes), which exhibit a similar feeding strategy. We assumed that they feed mainly on metabolites, which were reprocessed by the host and are therefore isotopically lighter. In contrast, the nematodes were enriched in the heavier isotope δ (15)N with respect to their host and the acanthocephalans, respectively. As active feeders they feed on tissues and blood in the body cavity of the host and thus showed isotope discrimination patterns resembling those of

  19. Tracing increasing tropical Andean glacier melt with stable isotopes in water. (United States)

    Mark, Bryan G; Mckenzie, Jeffrey M


    Glaciers in the tropical Andes are undergoing rapid retreat with potentially devastating consequences for populations who rely on them for water resources. We measured stable water isotope ratios in synoptically sampled streams discharging from glacierized watersheds to associate hydroisotopic variation with relative changes in glacierized area. A total of 73 water samples were collected from hydrological endmembers including streams, glacier meltwater, and groundwater during the dry seasons of 2004-2006 in the Callejon de Huaylas, a 5000 km2 watershed that drains the western side of the Cordillera Blanca in northern Perú. To differentiate the influence of elevation on isotopic values, we use samples from shallow groundwater springs and nonglacierized subcatchments to derive a local meteoric elevation effect. From published historical runoff data and satellite-mapped glacier cover, we estimate an average increase of 1.6 (+/-1.1)% in the specific discharge of the glacierized catchments as a function of isotopic changes from 2004 to 2006. These results confirm predicted short-term increases in discharge as glaciers melt and demonstrate the utility of stable isotopes in water for tracing relative glacier melt water contributions to watersheds.

  20. Characteristics of chemistry and stable isotopes in groundwater of the Chaobai River catchment, Beijing

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. [Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, J.; Wang, X. [Hydrogeology and Engineering Geology Team of Beijing, Beijing 100037 (China); Pang, Z. [Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China)


    Environmental isotopes and chemical compositions are useful tools for the study of groundwater flow systems. Groundwater of the Chaobai River catchment, Beijing was sampled for chemical and stable isotopes analyses in 2005. Geochemical signatures evolve progressively from CaMg-HCO{sub 3} to NaK-HCO{sub 3}, and then to Na-HCO{sub 3} compositions as groundwater flows from the mountain to discharge areas. Groundwater can be divided into two groups on the basis of stable isotope compositions: ancient groundwater and modern groundwater. Modern groundwater (-9.90/00 to -6.60/00 for δ{sup 18}O) plots along a line with a slope of 4.0 on a δ{sup 2}H versus δ{sup 18}O diagram, reflecting evaporation during the process of recharge, whereas ancient groundwater samples (30 to 12 Ka.) are different in isotopic composition (-11.00/00 and -68.20/00 for δ{sup 18}O and δ{sup 2}H, respectively), reflecting the cold and arid climate in the last glacial period. The results have important implications for groundwater management in Beijing City. (authors)

  1. Keratin decomposition by trogid beetles: evidence from a feeding experiment and stable isotope analysis. (United States)

    Sugiura, Shinji; Ikeda, Hiroshi


    The decomposition of vertebrate carcasses is an important ecosystem function. Soft tissues of dead vertebrates are rapidly decomposed by diverse animals. However, decomposition of hard tissues such as hairs and feathers is much slower because only a few animals can digest keratin, a protein that is concentrated in hairs and feathers. Although beetles of the family Trogidae are considered keratin feeders, their ecological function has rarely been explored. Here, we investigated the keratin-decomposition function of trogid beetles in heron-breeding colonies where keratin was frequently supplied as feathers. Three trogid species were collected from the colonies and observed feeding on heron feathers under laboratory conditions. We also measured the nitrogen (δ(15)N) and carbon (δ(13)C) stable isotope ratios of two trogid species that were maintained on a constant diet (feathers from one heron individual) during 70 days under laboratory conditions. We compared the isotopic signatures of the trogids with the feathers to investigate isotopic shifts from the feathers to the consumers for δ(15)N and δ(13)C. We used mixing models (MixSIR and SIAR) to estimate the main diets of individual field-collected trogid beetles. The analysis indicated that heron feathers were more important as food for trogid beetles than were soft tissues under field conditions. Together, the feeding experiment and stable isotope analysis provided strong evidence of keratin decomposition by trogid beetles.

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

    DEFF Research Database (Denmark)

    Wunderlich, Anja; Meckenstock, Rainer; Einsiedl, Florian


    In batch experiments, we studied the isotope fractionation in N and O of dissolved nitrate during dentrification. Denitrifying strains Thauera aromatica and “Aromatoleum aromaticum strain EbN1” were grown under strictly anaerobic conditions with acetate, benzoate, and toluene as carbon sources. 18O......-labeled water and 18O-labeled nitrite were added to the microcosm experiments to study the effect of putative backward reactions of nitrite to nitrate on the stable isotope fractionation. We found no evidence for a reverse reaction. Significant variations of the stable isotope enrichment factor ε were observed...... depending on the type of carbon source used. For toluene (ε15N, −18.1 ± 0.6‰ to −7.3 ± 1.4‰; ε18O, −16.5 ± 0.6‰ to −16.1 ± 1.5‰) and benzoate (ε15N, −18.9 ± 1.3‰; ε18O, −15.9 ± 1.1‰) less negative isotope enrichment factors were calculated compared to those derived from acetate (ε15N, −23.5 ± 1.9‰ to −22...

  3. Keratin decomposition by trogid beetles: evidence from a feeding experiment and stable isotope analysis (United States)

    Sugiura, Shinji; Ikeda, Hiroshi


    The decomposition of vertebrate carcasses is an important ecosystem function. Soft tissues of dead vertebrates are rapidly decomposed by diverse animals. However, decomposition of hard tissues such as hairs and feathers is much slower because only a few animals can digest keratin, a protein that is concentrated in hairs and feathers. Although beetles of the family Trogidae are considered keratin feeders, their ecological function has rarely been explored. Here, we investigated the keratin-decomposition function of trogid beetles in heron-breeding colonies where keratin was frequently supplied as feathers. Three trogid species were collected from the colonies and observed feeding on heron feathers under laboratory conditions. We also measured the nitrogen (δ15N) and carbon (δ13C) stable isotope ratios of two trogid species that were maintained on a constant diet (feathers from one heron individual) during 70 days under laboratory conditions. We compared the isotopic signatures of the trogids with the feathers to investigate isotopic shifts from the feathers to the consumers for δ15N and δ13C. We used mixing models (MixSIR and SIAR) to estimate the main diets of individual field-collected trogid beetles. The analysis indicated that heron feathers were more important as food for trogid beetles than were soft tissues under field conditions. Together, the feeding experiment and stable isotope analysis provided strong evidence of keratin decomposition by trogid beetles.

  4. Stable isotope geochemistry of the Ulldemolins Pb-Zn-Cu deposit (SW Catalonian Coastal Ranges, Spain)


    Vergel, M.M.


    The Pb-Zn-Cu deposit of Ulldemolins occurs within the Carboniferous sedimentary series of the southernmost Catalonian Coastal Ranges. It consists of sulphide-bearing calc-silicate assemblages, with epidote, Ca-amphiboles and Ca-garnet, which develop selectively along a dolomicrite bed near the contact with a granite porphyry. Two mineralisation styles can be differentiated: a) banded and b) irregular. Fluid inclusions and stable isotope compositions of sulphur in sulphides (sphalerite, galena...

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


    Day, James M. D.; Moynier, Frederic


    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 μ (238U/204Pb) 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...

  6. Evaluating cleansing effects on trace elements and stable isotope values in feathers of oiled birds. (United States)

    Valladares, Sonia; Moreno, Roćio; Jover, Lluis; Sanpera, Carola


    Feathers of seabirds are widely used as a nondestructive tissue for pollution monitoring of trace elements, as well as convenient samples for trophic ecology studies by means of stable isotope analysis (SIA). Nevertheless, feathers can be occasionally impregnated with oil from deliberate ship discharges and from massive oil spill accidents. The feather structure makes them effective traps for particles and are subject to external contamination. It is unknown to what extent the oil adhered to feathers can change trace element concentrations or stable isotope signatures. This study has two primary objectives: (1) to assess if there are differences between trace element concentrations and stable isotope signatures of oiled and clean feathers, and (2) to determine if the cleansing of oiled feathers using commonly applied techniques such as sodium hydroxide (NaOH) washes in combination with an organic solvent (hexane) is more effective than using NaOH alone. In order to do this, we analysed trace elements (Se, Hg, Pb, Cu and Zn) and stable isotopes (delta(13)C and delta(15)N) of individual feathers of yellow-legged gulls (Larus michahellis) which were affected by the 2002 Prestige oil spill in Galicia (NW Spain). Two sets of feathers were analysed, one group were oil-free (Control group) and the other had oil adhered to its surface (Oiled group). We expected to find differences between control and oiled feathers when cleaning exclusively with NaOH and no differences when using hexane. Our results did not show significant differences between Control and Oiled groups as a consequence of the cleansing method used. Unexpectedly, the additional cleansing with hexane resulted in decreasing selenium concentrations and increasing zinc and delta(15)N values in all groups of feathers.

  7. Evaluating gull diets: A comparison of conventional methods and stable isotope analysis (United States)

    Weiser, Emily L.; Powell, Abby N.


    Samples such as regurgitated pellets and food remains have traditionally been used in studies of bird diets, but these can produce biased estimates depending on the digestibility of different foods. Stable isotope analysis has been developed as a method for assessing bird diets that is not biased by digestibility. These two methods may provide complementary or conflicting information on diets of birds, but are rarely compared directly. We analyzed carbon and nitrogen stable isotope ratios of feathers of Glaucous Gull (Larus hyperboreus) chicks from eight breeding colonies in northern Alaska, and used a Bayesian mixing model to generate a probability distribution for the contribution of each food group to diets. We compared these model results with probability distributions from conventional diet samples (pellets and food remains) from the same colonies and time periods. Relative to the stable isotope estimates, conventional analysis often overestimated the contributions of birds and small mammals to gull diets and often underestimated the contributions of fish and zooplankton. Both methods gave similar estimates for the contributions of scavenged caribou, miscellaneous marine foods, and garbage to diets. Pellets and food remains therefore may be useful for assessing the importance of garbage relative to certain other foods in diets of gulls and similar birds, but are clearly inappropriate for estimating the potential impact of gulls on birds, small mammals, or fish. However, conventional samples provide more species-level information than stable isotope analysis, so a combined approach would be most useful for diet analysis and assessing a predator's impact on particular prey groups.

  8. Studies of plant terpenoid biosynthesis using 13C stable isotope labeling techniques (KIT Scientific Reports ; 7583)


    Ghirardo, Andrea


    This thesis aims to deepen our understanding of plant terpenoid biosynthesis and the regulation of the 2-C-methylerythritol-4-phosphate pathway (MEP) with respect to isoprene and monoterpene biosynthesis in plant. For this purposes, stable isotope techniques were employed, providing information on the carbon sources for terpenoids biosynthesis and C fluxes within the MEP pathway at various spatial and temporal scales, as well as giving insight into the regulation of enzymes from the MEP pathway.

  9. Strong linkage of polar cod (Boreogadus saida) to sea ice algae-produced carbon: Evidence from stomach content, fatty acid and stable isotope analyses (United States)

    Kohlbach, Doreen; Schaafsma, Fokje L.; Graeve, Martin; Lebreton, Benoit; Lange, Benjamin Allen; David, Carmen; Vortkamp, Martina; Flores, Hauke


    The polar cod (Boreogadus saida) is considered an ecological key species, because it reaches high stock biomasses and constitutes an important carbon source for seabirds and marine mammals in high-Arctic ecosystems. Young polar cod (1-2 years) are often associated with the underside of sea ice. To evaluate the impact of changing Arctic sea ice habitats on polar cod, we examined the diet composition and quantified the contribution of ice algae-produced carbon (αIce) to the carbon budget of polar cod. Young polar cod were sampled in the ice-water interface layer in the central Arctic Ocean during late summer 2012. Diets and carbon sources of these fish were examined using 4 approaches: (1) stomach content analysis, (2) fatty acid (FA) analysis, (3) bulk nitrogen and carbon stable isotope analysis (BSIA) and (4) compound-specific stable isotope analysis (CSIA) of FAs. The ice-associated (sympagic) amphipod Apherusa glacialis dominated the stomach contents by mass, indicating a high importance of sympagic fauna in young polar cod diets. The biomass of food measured in stomachs implied constant feeding at daily rates of ∼1.2% body mass per fish, indicating the potential for positive growth. FA profiles of polar cod indicated that diatoms were the primary carbon source, indirectly obtained via amphipods and copepods. The αIce using bulk isotope data from muscle was estimated to be >90%. In comparison, αIce based on CSIA ranged from 34 to 65%, with the highest estimates from muscle and the lowest from liver tissue. Overall, our results indicate a strong dependency of polar cod on ice-algae produced carbon. This suggests that young polar cod may be particularly vulnerable to changes in the distribution and structure of sea ice habitats. Due to the ecological key role of polar cod, changes at the base of the sea ice-associated food web are likely to affect the higher trophic levels of high-Arctic ecosystems.

  10. A 500-year dual stable isotope tree ring chronology of a Late Glacial cooling event (United States)

    Pauly, Maren; Helle, Gerhard; Büntgen, Ulf; Friedrich, Michael; Heinrich, Ingo; Kromer, Bernd; Nievergelt, Daniel; Reinig, Frederick; Riedel, Frank; Sookdeo, Adam; Treydte, Kerstin; Wacker, Lukas; Brauer, Achim


    A recent discovery of over 250 subfossil pine trees in Zürich (dated 14 000 - 11 000 cal BP) has provided the opportunity to study the inconsistent warming transition from the last ice age to the current interglacial. This period (the Late Glacial) has been extensively studied through the development of mostly non-tree ring palaeoclimate proxy records due to the intrigue of numerous prominent climate oscillations. However, such existing (lake sediment and ice core) records often lack the temporal resolution required to interpret rapid environmental changes. Tree rings can help to resolve such events due to their high resolution (annually-resolved) growth banding and absolute dating potential. Moreover, the analysis of stable isotopes can strongly improve the climate signal implemented in tree-ring width. Since numerous environmental conditions are all integrated in the rather simple ring-width series, measurements of chemical tree responses (via stable isotopes) can greatly refine the climate-growth-dynamics. In this study, we are developing a well replicated 500-year annually resolved dual stable isotope (δ18O, δ13C) chronology from tree-ring cellulose, in an effort to reconstruct the environmental dynamics of a short-term Late Glacial cooling event (13 950 - 13 450 cal BP) in an otherwise naturally warming world. We will present and discuss the biological response to this rapid climate oscillation in the face of low atmospheric CO2 concentrations and other site conditions without any human fingerprint.

  11. Using stable isotopes to assess dietary changes of American black bears from 1980 to 2001. (United States)

    Teunissen van Manen, Jennapher L; Muller, Lisa I; Li, Zheng-hua; Saxton, Arnold M; Pelton, Michael R


    We measured stable carbon and nitrogen isotope ratios in 117 hair samples from American black bears (Ursus americanus) in Great Smoky Mountains National Park, Tennessee, during 1980-2001 from live-trapped bears. We also collected hair from bears with known diets to compare with the wild bears. We hypothesized that biological factors (age, mass, and sex), food availability (hard mast and wild hogs (Sus scrofa)), and nuisance status would influence food selection by black bears and changes in their feeding history would be measureable using stable isotopes. We developed a set of a priori models using nine variables to examine changes in black bear stable isotope values. We found no support for changes in δ(13)C values associated with any of the nine variables we analyzed. Bears had enriched (15)N in years with low white oak mast production and depleted (15)N when white oak mast was abundant. Subadults had enriched (15)N compared with adults and older adults. Variation in δ(15)N increased from 1980-1991 to 1992-2000 when hard mast production had greater fluctuations. Bears in a better physical condition appeared more likely to access foods with higher protein content. In years of low white oak acorn production, larger bears and subadults likely turned to alternative food sources. The long-term variation detected in this study was important in identifying which bears were potentially more susceptible to changes in availability of hard mast.

  12. Possible effects of diagenesis on the stable isotope composition of amino acids in carbonaceous meteorites (United States)

    Engel, Michael H.


    The initial report of indigenous, non-racemic protein amino acids (L-enantiomer excess) in the Murchison meteorite was based on the fact that only eight of the twenty amino acids characteristic of all life on Earth was present in this stone1. The absence of the other protein amino acids indicated that contamination subsequent to impact was highly unlikely. The development of new techniques for determining the stable isotope composition of individual amino acid enantiomers in the Murchison meteorite further documented the extraterrestrial origins of these compounds2,3. The stable isotope approach continues to be used to document the occurrence of an extraterrestrial L-enantiomer excess of protein amino acids in other carbonaceous meteorites4. It has been suggested that this L-enantiomer excess may result from aqueous reprocessing on meteorite parent bodies4,5. Preliminary results of simulation experiments are presented that are used to determine the extent to which the stable isotope compositions of amino acid constituents of carbonaceous meteorites may have been altered by these types of diagenetic processes subsequent to synthesis.

  13. Stable carbon and nitrogen isotopes in vertical peat profiles of natural and drained boreal peatlands (United States)

    Nykänen, Hannu; Mpamah, Promise; Rissanen, Antti; Pitkänen, Aki; Turunen, Jukka; Simola, Heikki


    Peatlands form a significant carbon pool in the global carbon cycle. Change in peat hydrology, due to global warming is projected to change microbiological processes and peat carbon pool. We tested if bulk stable carbon and nitrogen isotopes serve as indicators of severe long term drying in peatlands drained for forestry. Depth profile analysis of peat, for their carbon and nitrogen content as well as their carbon and nitrogen stable isotopic signatures, were conducted for peatlands in southern and eastern Finland, having ombrotrophic and minerotrophic natural and corresponding drained pairs or separate drained sites. The selection of sites allowed us to compare changes due to different fertility and changes due to long term artificial drying. Drainage lasting over 40 years has led to changes in hydrology, vegetation, nutrient mineralization and respiration. Furthermore, increased nutrient uptake and possible recycling of peat nitrogen and carbon trough vegetation back to the peat surface, also possibly has an effect on the stable isotopic composition of peat carbon and nitrogen. We think that drainage induced changes somehow correspond to those caused by changed hydrology due to climate change. We will present data from these measurements and discuss their implications for carbon and nitrogen flows in peatlands.

  14. Geochemical and stable isotope characteristics of urban heavy rain in the downtown of Tokyo, Japan (United States)

    Uchiyama, Ryunosuke; Okochi, Hiroshi; Ogata, Hiroko; Katsumi, Naoya; Asai, Daisuke; Nakano, Takanori


    In order to make clear the impact of air pollution on the formation of sudden and locally-distributed heavy rain in urban area (hereafter Urban Heavy Rain: UHR), we analyzed inorganic ion concentration and stable isotope ratio of water (δD and δ18O) in rainwater. Rainwater samples were collected in Shinjuku, which is a representative downtown of Tokyo, Japan, during four years from October 2012 to December 2015. The concentration and wet deposition fluxes of acidic components (H+, NH4+, NO3-, and nss-SO42 -) in UHR were especially higher than those in other types of rain events, i.e. normal rain, typhoon heavy rain, and frontal heavy rain. UHR had distinctly lower stable isotope ratios than those in other urban rains with same rainfall amount and summer precipitation systems. There was a high negative correlation between δ18O and the distances from the sampling point to the formation area of UHR within 10 km, while there were high positive correlations between δ18O and the concentration of acidic components in UHR. These findings indicate that UHR could effectively scavenge acidic substances within cloud and suggest the use of stable isotope ratios as tracers of an urban heavy rain's water and in-cloud scavenging process.

  15. Recent Bayesian stable-isotope mixing models are highly sensitive to variation in discrimination factors. (United States)

    Bond, Alexander L; Diamond, Antony W


    Stable isotopes are now used widely in ecological studies, including diet reconstruction, where quantitative inferences about diet composition are derived from the use of mixing models. Recent Bayesian models (MixSIR, SIAR) allow users to incorporate variability in discrimination factors (delta13C or delta15N), or the amount of change in either delta13C or delta15N between prey and consumer, but to date there has been no systematic assessment of the effect of variation in delta13C or delta15N on model outputs. We used whole blood from Common Terns (Sterna hirundo) and muscle from their common prey items (fish and euphausiids) to build a series of mixing models in SIAR (stable isotope analysis in R) using various discrimination factors from the published literature for marine birds. The estimated proportion of each diet component was affected significantly by delta13C or delta15N. We also use recently published stable-isotope data on the reliance of critically endangered Balearic Shearwaters (Puffinus mauretanicus) on fisheries discards to show that discrimination factor choice can have profound implications for conservation and management actions. It is therefore crucial for researchers wishing to use mixing models to have an accurate estimate of delta13C and delta15N, because quantitative diet estimates can help to direct future research or prioritize conservation and management actions.

  16. Trophic ecology of sharks in the mid-east pacific ocean inferred from stable isotopes (United States)

    Li, Yunkai; Gong, Yi; Chen, Xinjun; Dai, Xiaojie; Zhu, Jiangfeng


    As apex predators, sharks are of ecological and conservation importance in marine ecosystems. In this study, trophic positions of sharks were estimated using stable isotope ratios of carbon and nitrogen for five representative species caught by the Chinese longline fleet in the mid-east Pacific, i.e., the blue shark (Prionace glauca), the bigeye thresher shark (Alopias superciliosus), the silky shark (Carcharhinus falciformis), the scalloped hammerhead (Sphyrna lewini), and the oceanic whitetip shark (Carcharhinus longimanus). Of these species, oceanic whitetip shark has the lowest trophic level and mean δ15N value (3.9 and 14.93‰ ± 0.84‰), whereas bigeye thresher shark has the highest level/values (4.5 and 17.02‰ ± 1.21‰, respectively). The bigeye thresher shark has significantly higher δ15N value than other shark species, indicating its higher trophic position. The blue shark and oceanic whitetip shark has significantly higher δ13C values than bigeye thresher shark, silky shark and scalloped hammerhead, possibly due to different diets and/or living habitats. The stable isotope data and stomach content data are highly consistent, suggesting that stable isotope analysis supplements traditional feeding ecology study of sharks, and thus contributes to understanding their trophic linkage.

  17. Neonatal Respiratory Diseases in the Newborn Infant: Novel Insights from Stable Isotope Tracer Studies. (United States)

    Carnielli, Virgilio P; Giorgetti, Chiara; Simonato, Manuela; Vedovelli, Luca; Cogo, Paola


    Respiratory distress syndrome is a common problem in preterm infants and the etiology is multifactorial. Lung underdevelopment, lung hypoplasia, abnormal lung water metabolism, inflammation, and pulmonary surfactant deficiency or disfunction play a variable role in the pathogenesis of respiratory distress syndrome. High-quality exogenous surfactant replacement studies and studies on surfactant metabolism are available; however, the contribution of surfactant deficiency, alteration or dysfunction in selected neonatal lung conditions is not fully understood. In this article, we describe a series of studies made by applying stable isotope tracers to the study of surfactant metabolism and lung water. In a first set of studies, which we call 'endogenous studies', using stable isotope-labelled intravenous surfactant precursors, we showed the feasibility of measuring surfactant synthesis and kinetics in infants using several metabolic precursors including plasma glucose, plasma fatty acids and body water. In a second set of studies, named 'exogenous studies', using stable isotope-labelled phosphatidylcholine tracer given endotracheally, we could estimate surfactant disaturated phosphatidylcholine pool size and half-life. Very recent studies are focusing on lung water and on the endogenous biosynthesis of the surfactant-specific proteins. Information obtained from these studies in infants will help to better tailor exogenous surfactant treatment in neonatal lung diseases. © 2016 S. Karger AG, Basel.

  18. Relative quantitation of proteins in expressed prostatic secretion with a stable isotope labeled secretome standard. (United States)

    Zhao, Ting; Zeng, Xuemei; Bateman, Nicholas W; Sun, Mai; Teng, Pang-Ning; Bigbee, William L; Dhir, Rajiv; Nelson, Joel B; Conrads, Thomas P; Hood, Brian L


    Expressed prostatic secretion (EPS) is a proximal fluid directly derived from the prostate and, in the case of prostate cancer (PCa), is hypothesized to contain a repertoire of cancer-relevant proteins. Quantitative analysis of the EPS proteome may enable identification of proteins with utility for PCa diagnosis and prognosis. The present investigation demonstrates selective quantitation of proteins in EPS samples from PCa patients using a stable isotope labeled proteome standard (SILAP) generated through the selective harvest of the "secretome" from the PC3 prostate cancer cell line grown in stable isotope labeled cell culture medium. This stable isotope labeled secretome was digested with trypsin and equivalently added to each EPS digest, after which the resultant mixtures were analyzed by liquid chromatography-tandem mass spectrometry for peptide identification and quantification. Relative quantification of endogenous EPS peptides was accomplished by comparison of reconstructed mass chromatograms to those of the chemically identical SILAP peptides. A total of 86 proteins were quantified from 263 peptides in all of the EPS samples, 38 of which were found to be relevant to PCa. This work demonstrates the feasibility of using a SILAP secretome standard to simultaneously quantify many PCa-relevant proteins in EPS samples.

  19. Using stable isotope techniques in nutrition assessments and tracking of global targets post-2015. (United States)

    Owino, Victor O; Slater, Christine; Loechl, Cornelia U


    Stable isotopes are non-radioactive, safe and are applied for various purposes in human health assessment in trace amounts that minimally disturb normal physiology. The International Atomic Energy Agency supports the use of stable isotope techniques to design and evaluate interventions addressing malnutrition in all its forms with focus on infant and young child feeding; maternal and adolescent nutrition; diet quality; prevention and control of non-communicable diseases; healthy ageing and gut function. These techniques can be used to objectively measure: (1) amount of human milk consumed and whether an infant is exclusively breastfed; (2) body composition in the context of re-feeding programmes for moderate and severe acute malnutrition and as an indicator of the risk for obesity; (3) bioavailability and bioconversion of pro-vitamin A and vitamin A body stores following vitamin A intervention programmes; (4) absorption and retention of iron, zinc and protein; (5) total energy expenditure for validation of physical activity measurement and dietary assessment tools and (6) diagnosis of Helicobacter pylori. Stable isotope techniques will be invaluable in the tracking of global targets on exclusive breast-feeding childhood obesity and anaemia among women. Efforts are underway to make nuclear techniques more affordable, field-friendly and less invasive, and to develop less sophisticated but precise equipment. Advocacy for the wide adoption of the techniques is needed.

  20. Stable Isotope Biogeochemistry of the Centennial Re-survey of the San Jacinto Mountains, CA (United States)

    Fogel, M. L.; Swarth, E.; Swarth, C.; Smith-Herman, N.; Tremor, S.; Unitt, P.


    In 1908, the San Jacinto Mountains were first surveyed for their animal and plant diversity by Joseph Grinnell and Harry Swarth, Museum of Vertebrate Zoology, UC Berkeley. In 2008, continuing until 2011, the ecology and stable isotope biogeochemistry of the plants, insects, birds, and mammals is being re-surveyed. Results of carbon, nitrogen, and hydrogen isotopes in organic matter show the variation in regional climate and trophic structure. For example, δ15N of plants at more arid stations are more positive by 3-5‰. Plants on westward facing slopes have more negative δ15N (to -6‰) possibly indicating N sources from atmospheric N deposition originating from urban Los Angeles. Isotopic analyses of recent collections will be compared with historic, museum archived specimens of plants and resident birds species. Our initial results show that the carbon isotopic compositions of plants collected in 1908 and during the early part of the 20th century are 1.6‰ enriched in δ13C, as predicted with the rise in industrially influenced atmospheric CO2. Isotopic data will be augmented by species diversity to test the hypothesis that 100 years of human influence has affected the ecosystem in this area and in what manner.

  1. Multi-factorial in vivo stable isotope fractionation: causes, correlations, consequences and applications. (United States)

    Schmidt, Hanns-Ludwig; Robins, Richard J; Werner, Roland A


    Many physical and chemical processes in living systems are accompanied by isotope fractionation on H, C, N, O and S. Although kinetic or thermodynamic isotope effects are always the basis, their in vivo manifestation is often modulated by secondary influences. These include metabolic branching events or metabolite channeling, metabolite pool sizes, reaction mechanisms, anatomical properties and compartmentation of plants and animals, and climatological or environmental conditions. In the present contribution, the fundamentals of isotope effects and their manifestation under in vivo conditions are outlined. The knowledge about and the understanding of these interferences provide a potent tool for the reconstruction of physiological events in plants and animals, their geographical origin, the history of bulk biomass and the biosynthesis of defined representatives. It allows the use of isotope characteristics of biomass for the elucidation of biochemical pathways and reaction mechanisms and for the reconstruction of climatic, physiological, ecological and environmental conditions during biosynthesis. Thus, it can be used for the origin and authenticity control of food, the study of ecosystems and animal physiology, the reconstruction of present and prehistoric nutrition chains and paleaoclimatological conditions. This is demonstrated by the outline of fundamental and application-orientated examples for all bio-elements. The aim of the review is to inform (advanced) students from various disciplines about the whole potential and the scope of stable isotope characteristics and fractionations and to provide them with a comprehensive introduction to the literature on fundamental aspects and applications.

  2. Feeding ecology and niche overlap of Lake Ontario offshore forage fish assessed with stable isotopes (United States)

    Mumby, James; Johson, Timothy; Stewart, Thomas; Halfyard, Edward; Walsh, Maureen; Weidel, Brian C.; Lantry, Jana; Fisk, Aarron


    The forage fish communities of the Laurentian Great Lakes continue to experience changes that have altered ecosystem structure, yet little is known about how they partition resources. Seasonal, spatial and body size variation in δ13C and δ15N was used to assess isotopic niche overlap and resource and habitat partitioning among the five common offshore Lake Ontario forage fish species (n = 2037) [Alewife (Alosa pseudoharengus), Rainbow Smelt (Osmerus mordax), Round Goby (Neogobius melanostomus), and Deepwater (Myoxocephalus thompsonii) and Slimy (Cottus cognatus) Sculpin]. Round Goby had the largest isotopic niche (6.1‰2, standard ellipse area (SEAC)), followed by Alewife (3.4‰2) while Rainbow Smelt, Slimy Sculpin and Deepwater Sculpin had the smallest and similar niche size (1.7-1.8‰2), with only the Sculpin species showing significant isotopic niche overlap (>63%). Stable isotopes in Alewife, Round Goby and Rainbow Smelt varied with location, season and size, but did not in the Sculpin spp. Lake Ontario forage fish species have partitioned food and habitat resources, and non-native Alewife and Round Goby have the largest isotopic niche, suggestive of a boarder ecological niche, and may contribute to their current high abundance.

  3. Zinc stable isotope fractionation upon accelerated oxidative weathering of sulfidic mine waste. (United States)

    Matthies, R; Krahé, L; Blowes, D W


    Accelerated oxidative weathering in a reaction cell (ASTM D 5744 standard protocol) was performed over a 33 week period on well characterized, sulfidic mine waste from the Kidd Creek Cu-Zn volcanogenic massive sulfide deposit, Canada. The cell leachate was monitored for physicochemical parameters, ion concentrations and stable isotope ratios of zinc. Filtered zinc concentrations (isotope ratios varied mass-dependently within +0.1 and +0.52‰ relative to IRMM 3702, and were strongly dependent on the pH (rpH-d66Zn=0.65, pisotope signature of sphalerite (+0.1 to +0.16‰). Desorption processes resulted in enrichment of (66)Zn in the leachate reaching a maximum offset of +0.32‰ compared to the proposed sphalerite isotope signature. Over a period characterized by pH=6.1 ± 0.6, isotope ratios were significantly more enriched in (66)Zn with an offset of ≈ 0.23‰ compared to sphalerite, suggesting that zinc release may have been derived from a second zinc source, such as carbonate minerals, which compose 8 wt.% of the tailings. This preliminary study confirms the benefit of applying zinc isotopes alongside standard monitoring parameters to track principal zinc sources and weathering processes in complex multi-phase matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. What climate information is recorded in stable isotope ratios of wood lignin methoxyl groups? (United States)

    Greule, Markus; Keppler, Frank


    The stable isotope composition of the bioelements C, O, H and N in plant organic matter is known to be a very powerful for various environmental impacts. Particularly tree rings are suitable for this analysis because they exhibit a "climate archive" with a yearly or even biannual resolution. One of the most determined wood compounds is cellulose which amongst others is used to reconstruct the temperature due to measurement of stable hydrogen and oxygen isotopes. Therefore cellulose is converted into cellulose nitrate to eliminate the exchangeable hydroxyl hydrogen or equilibration methods are used. However, a general problem associated with the determination of the stable hydrogen values of marker compounds for the study of climate and environmental conditions is the isolation of the pure compound for analysis by isotope ratio mass spectrometry. Exploitation of components of wood as markers, in particular, has been restricted by the very labour intensive and time consuming preparation of samples (e.g. cellulose nitrate). An alternative way to record climate information from tree rings was recently proposed by Keppler et al. (2007) who measured the stable hydrogen values of methoxyl groups in wood. Lignin methoxyl groups are considered to be stable, i.e. the hydrogen atoms of the methoxyl moiety do not exchange with those of plant water during ongoing metabolic reactions in the plant. Thus the initial deuterium content of the methoxyl groups of lignin in woody tissue at formation is retained throughout the lifetime of the tree and in preserved tissue. The methoxyl content of lignin in wood is usually determined by the Zeisel method (Zeisel, 1885) - the reaction between methyl ethers and hydroiodic acid to form methyl iodide. Exploiting this reaction for the measurement of stable hydrogen values of lignin methoxyl groups ensures that during the entire analytical procedure the isotope signal is preserved since no isotopic exchange occurs between the methyl groups and

  5. The neodymium stable isotope composition of the silicate Earth and chondrites (United States)

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


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

  6. Stable isotope distribution in continental Maastrichtian vertebrates from the Haţeg Basin, South Carpathians (United States)

    Bojar, Ana-Voica; Csiki, Zoltan; Grigorescu, Dan


    The oxygen isotopic compositions of biogenic apatite from crocodiles, turtles and dinosaurs, and their relationship to climate and physiology have been evidenced by several studies (Barrick and Showers, 1995; Kolodny et al., 1996; Barrick et al., 1999; Fricke and Rogers, 2000; Stoskopf et al., 2001; Straight et al., 2004; Amiot et al., 2007). To date, few attempts have been made to correlate the enamel d13C to dietary resources of dinosaurs (Bocherens et al., 1988; Stanton Thomas and Carlson, 2004; Fricke and Pearson, 2008; Fricke, et al., 2008). One additional complication is that for dinosaurs, the d18O of enamel phosphate depends on both body water and variations in body temperature. Several studies addressed the issue of endothermy vs. ectothermy of fossil vertebrates by studying inter- and intra-bone and enamel isotopic variability (Barrick and Showers, 1994, 1995; Barrick et al., 1996; 1998; Fricke and Rogers, 2000). More recent investigations provided evidence for inter-tooth temporal variations and related them to seasonality and/or changes in physiology (Straight et al., 2004; Stanton Thomas and Carlson, 2004). The main objectives of this study are to extract palaeoclimatic information considering, beside lithofacial characteristics and the isotopic distribution of carbonates formed in paleosols, the stable isotope composition of vertebrate remains from the Haţeg Basin. We also sampled several teeth along their growth axis in order to get further information about growth rates and the amplitude of isotopic variation. Located in the South Carpathians in Romania, the Haţeg Basin contains a thick sequence of Maastrichtian continental deposits yielding a rich dinosaur and mammalian fauna. Stable isotope analyses of both calcretes and dinosaur, crocodilian and turtle remains from two localities (Tuştea and Sibişel) were integrated in order to reconstruct environmental conditions during the Maastrichtian time and to gain further insights into the metabolism

  7. Ca, Sr and Ba stable isotopes reveal the fate of soil nutrients along a tropical climosequence (United States)

    Bullen, Thomas D.; Chadwick, Oliver A.


    Nutrient biolifting is an important pedogenic process in which plant roots obtain inorganic nutrients such as phosphorus (P) and calcium (Ca) from minerals at depth and concentrate those nutrients at the surface. Here we use soil chemistry and stable isotopes of the alkaline earth elements Ca, strontium (Sr) and barium (Ba) to test the hypothesis that biolifting of P has been an important pedogenic process across a soil climosequence developed on volcanic deposits at Kohala Moun