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Sample records for 13c stable isotope

  1. Stable isotope-enhanced two- and three-dimensional diffusion ordered 13C-NMR spectroscopy (SIE-DOSY 13C-NMR)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable Isotope-Enhanced Diffusion Ordered (SIE-DOSY) 13C-NMR has been applied to 13C-enriched carbohydrates and has been used to determine diffusion coefficients for pentose and hexose monosaccharides, a disaccharide and a trisaccharide. These 2D spectra were obtained with as little as 8 min of acq...

  2. Stable isotope-enhanced two- and three-dimensional diffusion ordered 13C NMR spectroscopy (SIE-DOSY 13C NMR)

    NASA Astrophysics Data System (ADS)

    Vermillion, Karl; Price, Neil P. J.

    2009-06-01

    The feasibility of obtaining high quality homonuclear or heteronuclear diffusion-ordered 13C NMR data is shown to be greatly improved by using 13C isotopically-enriched samples. Stable isotope-enhanced diffusion ordered (SIE-DOSY) 13C NMR has been applied to 13C-enriched carbohydrates, and has been used to determine diffusion coefficients for pentose and hexose monosaccharides, and a disaccharide and trisaccharide. These 2D spectra were obtained with as little as 8 min of acquisition time. Fully resolved 3D DOSY-HMQC NMR spectra of [U- 13C]xylose, [U- 13C]glucose, and [1- 13C gal]lactose were obtained in 5 h. Sample derivatization with [ carbonyl- 13C]acetate (peracetylation) extends the usefulness of the technique to included non-labeled sugars; the 13C-carbonyl - carbohydrate ring proton 1H- 13C correlations also provide additional structural information, as shown for the 3-D DOSY-HMQC analysis of a mixture of maltotriose and lactose per-[ carbonyl- 13C]acetates.

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

    PubMed

    Gratton, Claudio; Forbes, Andrew E

    2006-04-01

    Traditionally, researchers have used measurements of carbon stable isotopes to infer the composition of consumers' diets. However, since consumer's tissues may process carbon isotopes differently, particularly following a diet shift, it is possible to use measurements of carbon isotopes in multiple tissues to determine not only the composition of an individual's diet, but also the temporal dynamics thereof. This study examined how stable isotopes of carbon (13C/12C, expressed as delta 13C) changed in different adult tissues of two predacious beetles, Harmonia axyridis and Coccinella septempunctata (Coleoptera: Coccinellidae). In the laboratory, we switched ladybeetles from a C3-based diet (soybean aphids, Aphis glycines) to a C4-based one (corn leaf aphids, Rhopalosiphum maidis). The delta 13C of metabolically active tissues such as the body fat and reproductive organs changed rapidly (< or =5 days) following the diet shift. Tissues expected to be more metabolically inert, such as wings, changed more slowly over the same period. Although these general patterns were largely similar between males and females, females had more rapid changes in delta 13C in fat and reproductive tissues. However, females showed a significant depletion in delta 13C after 10 days, while males' delta 13C continued to increase. Given the results of this experiment, it is now possible to distinguish between ladybeetles eating a mixed diet (beetles with multiple tissues at similar, intermediate, equilibrial delta 13C signatures) from those that have shifted diets (beetles with different tissues at distinctly different delta 13C values). Thus, this approach can be used broadly to infer not only what constitutes the diet of a consumer, but also the temporal history of dietary intake. PMID:16341886

  4. On the status of IAEA delta-13C stable isotope reference materials.

    NASA Astrophysics Data System (ADS)

    Assonov, Sergey; Groening, Manfred; Fajgelj, Ales

    2016-04-01

    For practical reasons all isotope measurements are performed on relative scales realized through the use of international, scale-defining primary standards. In fact these standards were materials (artefacts, similar to prototypes of meter and kg) selected based on their properties. The VPDB delta-13C scale is realised via two highest-level reference materials NBS19 and LSVEC, the first defining the scale and the second aimed to normalise lab-to-lab calibrations. These two reference materials (RMs) have been maintained and distributed by IAEA and NIST. The priority task is to maintain these primary RMs at the required uncertainty level, thus ensuring the long-term scale consistency. The second task is to introduce replacements when needed (currently for exhausted NBS19, work in progress). The next is to produce a family of lower level RMs (secondary, tertiary) addressing needs of various applications (with different delta values, in different physical-chemical forms) and their needs for the uncertainty; these RMs should be traceable to the highest level RMs. Presently three is a need for a range of RMs addressing existing and newly emerging analytical techniques (e.g. optical isotopic analysers) in form of calibrated CO2 gases with different delta-13C values. All that implies creating a family of delta-13C stable isotope reference materials. Presently IAEA works on replacement for NBS19 and planning new RMs. Besides, we found that LSVEC (introduced as second anchor for the VPDB scale in 2006) demonstrate a considerable scatter of its delta-13C value which implies a potential bias of the property value and increased value uncertainty which may conflict with uncertainty requirements for atmospheric monitoring. That is not compatible with the status of LSVEC, and therefore it should be replaced as soon as possible. The presentation will give an overview of the current status, the strategic plan of developments and the near future steps.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    13C abundance in the quinone. In this study, we verified carbon stable isotope of quinone compared with bulk carbon stable isotope of bacterial culture. Results indicated a good correlation between carbon stable isotope of quinone compared with bulk carbon stable isotope. However, our measurement conditions for detection of quinone isotope-ions incurred underestimation of 13C abundance in the quinone. The quinone-SIP technique needs further optimization for measurement conditions of LC-MS/MS.

  6. Application of (13)C-stable isotope probing to identify RDX-degrading microorganisms in groundwater.

    PubMed

    Cho, Kun-Ching; Lee, Do Gyun; Roh, Hyungkeun; Fuller, Mark E; Hatzinger, Paul B; Chu, Kung-Hui

    2013-07-01

    We employed stable isotope probing (SIP) with (13)C-labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to identify active microorganisms responsible for RDX biodegradation in groundwater microcosms. Sixteen different 16S rRNA gene sequences were derived from microcosms receiving (13)C-labeled RDX, suggesting the presence of microorganisms able to incorporate carbon from RDX or its breakdown products. The clones, residing in Bacteroidia, Clostridia, α-, β- and δ-Proteobacteria, and Spirochaetes, were different from previously described RDX degraders. A parallel set of microcosms was amended with cheese whey and RDX to evaluate the influence of this co-substrate on the RDX-degrading microbial community. Cheese whey stimulated RDX biotransformation, altered the types of RDX-degrading bacteria, and decreased microbial community diversity. Results of this study suggest that RDX-degrading microorganisms in groundwater are more phylogenetically diverse than what has been inferred from studies with RDX-degrading isolates. PMID:23603473

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

    PubMed

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

    2016-07-01

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

  8. Stable Carbon Isotopes13C) in Coral Skeletons: Experimental Approach and Applications for Paleoceanography

    NASA Astrophysics Data System (ADS)

    Grottoli, A. G.

    2004-12-01

    natural field conditions corals feed on zooplankton below this `nutrient threshold' and that increases in heterotrophy should result in decreases skeletal δ 13C values. Overall, changes in photosynthesis and heterotrophy have significant effects on coral skeletal δ 13C. In shallower corals, photosynthesis drives the bulk of the variation in δ 13C. In addition, boron isotope data indicate that pH levels do not vary with changes in photosynthesis or heterotrophy suggesting that metabolically driven δ 13C fractionation during skeletogenesis is not pH driven. Thus the skeletal δ 13C records from shallow corals in non-upwelling regions where zooplankton concentrations are relatively constant should represent a reliable proxy of light variability. Due to the complexity associated with nutrients and heterotrophy, δ 13C records from upwelling regions or deep corals are still difficult to resolve.

  9. Tracing the diet of the monitor lizard Varanus mabitang by stable isotope analyses (δ15N, δ13C)

    NASA Astrophysics Data System (ADS)

    Struck, Ulrich; Altenbach, Alexander; Gaulke, Maren; Glaw, Frank

    2002-09-01

    In this study, we used analyses of stable isotopes of nitrogen (δ15N) and carbon (δ13C) to determine the trophic ecology of the monitor lizard Varanus mabitang. Stable isotopes from claws, gut contents, and soft tissues were measured from the type specimen. Samples from Varanus olivaceus, Varanus prasinus, Varanus salvator, the herbivorous agamid lizard Hydrosaurus pustulatus, and some plant matter were included for comparison. Our data show a rapid decrease in δ13C (about10‰) from food plants towards gut contents and soft tissues of herbivorous species. For the varanids, we found a significant linear correlation of decreasing δ13C and increasing δ15N from herbivorous towards carnivorous species. In terms of trophic isotope ecology, the type specimen of V. mabitang is a strict herbivore. Thus it differs significantly in its isotopic composition from the morphologically next closest related species V. olivaceus. The most highly carnivorous species is V. salvator, while δ15N values for V. prasinus and V. olivaceus are intermediate. Claws provide very valuable samples for such measurements, because they can be sampled from living animals without harm. Additionally, their range of variability is relatively small in comparison with measurements from soft tissues.

  10. Stable isotope (13C, 15N and 34S) analysis of the hair of modern humans and their domestic animals.

    PubMed

    Bol, Roland; Pflieger, Christian

    2002-01-01

    Relationships between dietary status and recent migration were examined by delta(13)C, delta(15)N and delta(34)S analysis of hair samples from 43 modern humans living in a rural community in SW England. The isotopic content of 38 'local' hair samples was compared with that of five recently arrived individuals (from Canada, Chile, Germany and the USA). Hair samples from domestic animals (i.e. mainly cats, dogs, cows and horses) were analysed to examine the difference in delta(13)C, delta(15)N and delta(34)S values between herbivores and carnivores. Generally, modern human hair data from the triple stable isotope (delta(13)C, delta(15)N and delta(34)S) provided enough information to confirm the dietary status and origin of the individual subjects. The dietary intake was generally reflected in the animal hair delta(15)N and delta(13)C values, i.e. highest in the carnivores (cats). However, a non-local origin of food sources given to domesticated omnivores (i.e. dogs) was suggested by their hair delta(34)S values. PMID:12442295

  11. Continuous flow stable isotope methods for study of δ13C fractionation during halomethane production and degradation

    USGS Publications Warehouse

    Kalin, Robert M.; Hamilton, John T.G.; Harper, David B.; Miller, Laurence G.; Lamb, Clare; Kennedy, James T.; Downey, Angela; McCauley, Sean; Goldstein, Allen H.

    2001-01-01

    Gas chromatography/mass spectrometry/isotope ratio mass spectrometry (GC/MS/IRMS) methods for δ13C measurement of the halomethanes CH3Cl, CH3Br, CH3I and methanethiol (CH3SH) during studies of their biological production, biological degradation, and abiotic reactions are presented. Optimisation of gas chromatographic parameters allowed the identification and quantification of CO2, O2, CH3Cl, CH3Br, CH3I and CH3SH from a single sample, and also the concurrent measurement of δ13C for each of the halomethanes and methanethiol. Precision of δ13C measurements for halomethane standards decreased (±0.3, ±0.5 and ±1.3‰) with increasing mass (CH3Cl, CH3Br, CH3I, respectively). Given that carbon isotope effects during biological production, biological degradation and some chemical (abiotic) reactions can be as much as 100‰, stable isotope analysis offers a precise method to study the global sources and sinks of these halogenated compounds that are of considerable importance to our understanding of stratospheric ozone destruction. 

  12. Stable isotope analysis (δ13C and δ15N) of soil nematodes from four feeding groups

    PubMed Central

    Griffiths, Bryan; Dyckmans, Jens; Schmidt, Olaf

    2016-01-01

    Soil nematode feeding groups are a long-established trophic categorisation largely based on morphology and are used in ecological indices to monitor and analyse the biological state of soils. Stable isotope ratio analysis (13C/12C and 15N/14N, expressed as δ13C and δ15N) has provided verification of, and novel insights into, the feeding ecology of soil animals such as earthworms and mites. However, isotopic studies of soil nematodes have been limited to date as conventional stable isotope ratio analysis needs impractically large numbers of nematodes (up to 1,000) to achieve required minimum sample weights (typically >100 µg C and N). Here, micro-sample near-conventional elemental analysis–isotopic ratio mass spectrometry (μEA–IRMS) of C and N using microgram samples (typically 20 µg dry weight), was employed to compare the trophic position of selected soil nematode taxa from four feeding groups: predators (Anatonchus and Mononchus), bacterial feeders (Plectus and Rhabditis), omnivores (Aporcelaimidae and Qudsianematidae) and plant feeder (Rotylenchus). Free-living nematodes were collected from conventionally and organically managed arable soils. As few as 15 nematodes, for omnivores and predators, were sufficient to reach the 20 µg dry weight target. There was no significant difference in δ15N (p = 0.290) or δ13C (p = 0.706) between conventional and organic agronomic treatments but, within treatments, there was a significant difference in N and C stable isotope ratios between the plant feeder, Rotylenchus (δ15N = 1.08 to 3.22 mUr‰, δ13C = –29.58 to –27.87 mUr) and all other groups. There was an average difference of 9.62 mUr in δ15N between the plant feeder and the predator group (δ15N = 9.89 to 12.79 mUr, δ13C = –27.04 to –25.51 mUr). Isotopic niche widths were calculated as Bayesian derived standard ellipse areas and were smallest for the plant feeder (1.37 mUr2) and the predators (1.73 mUr2), but largest for omnivores (3.83 mUr2

  13. Nic1 Inactivation Enables Stable Isotope Labeling with 13C615N4-Arginine in Schizosaccharomyces pombe*

    PubMed Central

    Carpy, Alejandro; Patel, Avinash; Tay, Ye Dee; Hagan, Iain M.; Macek, Boris

    2015-01-01

    Stable Isotope Labeling by Amino Acids (SILAC) is a commonly used method in quantitative proteomics. Because of compatibility with trypsin digestion, arginine and lysine are the most widely used amino acids for SILAC labeling. We observed that Schizosaccharomyces pombe (fission yeast) cannot be labeled with a specific form of arginine, 13C615N4-arginine (Arg-10), which limits the exploitation of SILAC technology in this model organism. We hypothesized that in the fission yeast the guanidinium group of 13C615N4-arginine is catabolized by arginase and urease activity to 15N1-labeled ammonia that is used as a precursor for general amino acid biosynthesis. We show that disruption of Ni2+-dependent urease activity, through deletion of the sole Ni2+ transporter Nic1, blocks this recycling in ammonium-supplemented EMMG medium to enable 13C615N4-arginine labeling for SILAC strategies in S. pombe. Finally, we employed Arg-10 in a triple-SILAC experiment to perform quantitative comparison of G1 + S, M, and G2 cell cycle phases in S. pombe. PMID:25368411

  14. In vitro development and validation of a non-invasive (13)C-stable isotope assay for ornithine decarboxylase.

    PubMed

    Jaenisch, Simone; Squire, Michelle; Butler, Ross; Yazbeck, Roger

    2016-06-01

    Oesophageal cancer is a significant cause of cancer related mortality, with increasing incidence worldwide. Ornithine decarboxylase (ODC) is an enzyme involved in polyamine synthesis and cellular proliferation, and ODC expression and activity has been implicated as a prognostic marker of oesophageal cancer. This study aimed to develop and optimise an in vitro (13)C-stable isotope assay for ODC activity as a non-invasive marker of oesophageal cancer. Experiments were performed in triplicate (n  =  3/group/cell line) using Caco2, HeLa, Flo-1, OE33, TE7 and OE21 cell lines (colorectal, cervical, oesophageal adenocarcinoma and oesophageal squamous carcinoma respectively). Following addition of 2mM (13)C-ornithine to cells, 10 ml gas samples were collected from the headspace every 20 min for a total of five hours. Gas samples were analysed using isotope ratio mass spectrometry to quantify (13)CO2. Assay specificity was determined using the selective ODC inhibitor, N-(4'-Pyridoxil)-Ornithine(BOC)-OMe (POB). All data is expressed as δ (13)CO2 from baseline. High ODC activity was detected by (13)C-ornithine assay in Caco2 (32.00  ±  1.12 δ (13)CO2) in contrast to HeLa cells (5.44  ±  0.14 δ (13)CO2) cells. POB inhibited activity in Caco2 cells to 12.87  ±  1.10 δ (13)CO2. Differential ODC activity was detected in all oesophageal cancer cells, and 53 h incubation of cell lines with POB reduced activity by 72%, 56%, 64% and 69% in the Flo-1, OE33, OE21 and TE7 cell lines respectively. We have shown that ODC activity can be selectively detected by a non-invasive, stable-isotope (13)C-ornithine assay. ODC activity was detected in all oesophageal cancer cell lines in vitro. Further studies are indicated to quantify ODC activity in oesophageal cancer patients. PMID:27137347

  15. Characterising ontogenetic niche shifts in Nile crocodile using stable isotope13C, δ15N) analyses of scute keratin.

    PubMed

    Radloff, Frans G T; Hobson, Keith A; Leslie, Alison J

    2012-09-01

    Nile crocodiles undergo a three to five order of magnitude increase in body size during their lifespan. This shift coincides with a change in resource and habitat use which influences the strength, type and symmetry of interactions with other species. Identifying size-specific crocodile groups displaying similar traits is important for conservation planning. Here, we illustrate how stable carbon (δ(13) C) and nitrogen (δ(15) N) isotope analysis of scute keratin, together with breakpoint modelling analysis can be used to characterise ontogenetic niche shifts. Using a sample set of 238 crocodiles from the Okavango Delta, Botswana (35-463 cm total length), we found prominent size-related changes in the scute keratin δ(13) C and δ(15) N profiles close to 40 and 119 cm snout-vent length. The first shift corroborated the findings of a traditional stomach-content study conducted on the same population at the same time, and the second conformed to known crocodile ecology. This approach can be used as a first approximation to identify size-specific groups within crocodile populations, and these can then be investigated further using isotopic or other methods. PMID:22462522

  16. Ontogeny and habitat change in Mesozoic cephalopods revealed by stable isotopes ( δ18O, δ13C)

    NASA Astrophysics Data System (ADS)

    Lukeneder, Alexander; Harzhauser, Mathias; Müllegger, Stefan; Piller, Werner E.

    2010-07-01

    Stable isotope ( δ18O and δ13C) ratios were measured in successive aragonitic shell sequences of ammonoids (class Cephalopoda) to determine whether their depth distributions changed within ontogeny and whether stable isotope values differ in various morphological groups (e.g. Leiostraca vs. Trachyostraca). We concentrate mainly on δ18O for temperature results and added δ13C data to obtain information on the ontogenetic history, for which full spiral measurements were undertaken for the first time. To obtain valid stable isotope data from ammonoid shells, we measured ontogenetic sequences (full shell) within different genera. Data sets from the Jurassic ( Cadoceras) and Cretaceous ( Hypacanthoplites, Nowakites) were chosen due to the pure primary aragonitic shell preservation. The study was designed to extract better information on the habitat and life cycle of fossil cephalopods (e.g. ammonoids) in comparison with recent cephalopods (e.g. Nautilus, Spirula, Sepia) possessing equivalent or comparable hard parts. The data from three genera suggest different modes of life in at least two morphological groups. We detected and established two main groups with different ontogenetic strategies based on the δ18O data. The wcw-type (warm-cool-warm type) of Cadoceras resembles strategies in Nautilus and Sepia, which migrate from shallow into deeper environments and back in ontogeny ( wc-type, warm-cool-type), and the cw-type (cool-warm type) of Hypacanthoplites resembling the first two migration phases of Spirula ( cwc-type), which migrates from deeper into shallower and back again into deeper habitats. The main (three) phases revealed by both δ18O and δ13C data sets most probably reflect diet changes in juvenile to mid-aged individuals, followed by a habitat change for spawning adults. In Cadoceras the temperatures range from 21.2 °C for juveniles down to 12.1 °C for mid-aged individuals and back up 16.9 °C in adults. The cw- type strategy of Hypacanthoplites

  17. The stable isotopic composition of a phosphorite deposit: δ13C, δ34S, and δ18O

    USGS Publications Warehouse

    Piper, D.Z.; Kolodny, Y.

    1987-01-01

    The stable isotopes of carbon and sulfur in a major marine sedimentary phosphate deposit from the northwestern United States (the Phosphoria Formation of Permian age) characterize the chemical properties of the depositional environment. The δ34S and δ13C analyses suggest deposition under conditions of variable redox from a solution the acidity of which was controlled by reaction with carbonate rocks and exchange with seawater. The δ18O concentration of apetite indicates phosphatization in a shallow sea, during three glacial and intervening interglacial stages. These data tend to corroborate the interpretation of field studies by others, that the apatite formed on a continental shelf in an area of intense oceanic upwelling during several episodes of sea level change. 

  18. Analysing Groundwater Using the 13C Isotope

    NASA Astrophysics Data System (ADS)

    Awad, Sadek

    The stable isotope of the carbon atom (13C) give information about the type of the mineralisation of the groundwater existing during the water seepage and about the recharge conditions of the groundwater. The concentration of the CO2(aq.) dissolved during the infiltration of the water through the soil's layers has an effect on the mineralisation of this water. The type of the photosynthesis's cycle (C-3 or C-4 carbon cycle) can have a very important role to determine the conditions (closed or open system) of the mineralisation of groundwater. The isotope 13C of the dissolved CO2 in water give us a certain information about the origin and the area of pollution of water. The proportion of the biogenic carbon and its percentage in the mineralisation of groundwater is determined by using the isotope 13C.

  19. Evaluating mercury biomagnification in fish from a tropical marine environment using stable isotopes (delta13C and delta15N).

    PubMed

    Al-Reasi, Hassan A; Ababneh, Fuad A; Lean, David R

    2007-08-01

    Concentrations of total mercury (T-Hg) and methylmercury (MeHg) were measured in zooplankton and 13 fish species from a coastal food web of the Gulf of Oman, an arm of the Arabian Sea between Oman and Iran. Stable isotope ratios (delta13C and delta15N) also were determined to track mercury biomagnification. The average concentration of T-Hg in zooplankton was 21 +/- 8.0 ng g(-1) with MeHg accounting 10% of T-Hg. Total mercury levels in fish species ranged from 3.0 ng g(-1) (Sardinella longiceps) to 760 ng g(-1) (Rhizoprionodon acutus) with relatively lower fraction of MeHg (72%) than that found in other studies. The average trophic difference (Deltadelta13C) between zooplankton and planktivorous fish (Selar crumenopthalmus, Rastrelliger kanagurta, and S. longiceps) was higher (3.4 per thousandth) than expected, suggesting that zooplankton may not be the main diet or direct carbon source for these fish species. However, further sampling would be required to compensate for temporal changes in zooplankton and the influence of their lipid content. Trophic position inferred by delta15N and and slopes of the regression equations (log10[T-Hg] = 0.13[delta15N] - 3.57 and log10[MeHg] = 0.14[delta15N] - 3.90) as estimates of biomagnification indicate that biomagnification of T-Hg and MeHg was lower in this tropical ocean compared to what has been observed in arctic and temperate ecosystems and tropical African lakes. The calculated daily intake of methylmercury in the diet of local people through fish consumption was well below the established World Health Organization (WHO) tolerable daily intake threshold for most of the fish species except Euthynnus affinis, Epinephelus epistictus, R. acutus, and Thunnus tonggol, illustrating safe consumption of the commonly consumed fish species. PMID:17702328

  20. Food partitioning of leaf-eating mangrove crabs ( Sesarminae): Experimental and stable isotope ( 13C and 15N) evidence

    NASA Astrophysics Data System (ADS)

    Kristensen, Ditte K.; Kristensen, Erik; Mangion, Perrine

    2010-05-01

    The feasibility of mangrove leaves as a full diet for sesarmid crabs has been questioned for decades. Since these leaves are nitrogen-poor, sesarmids probably obtain nitrogen from other sources to sustain growth. The aim of this study was to assess the food partitioning of the sesarmid species Neoepisesarma versicolor with emphasis on nitrogen allocation. The preference for animal tissue when crabs were pre-fed diets of different nitrogen content was determined in the laboratory. Furthermore, the possible in situ diet composition of N. versicolor was established from carbon and nitrogen stable isotope signature ( δ13C and δ15N) of freshly caught individuals and their potential food sources, using a concentration-dependent mixing model. N. versicolor showed significantly higher feeding preferences for fish meat when pre-fed leaf material without than with access to meat, indicating that this crab species can meet its nitrogen demand by ingesting animal tissue. The stable isotope mixing model based on in situ materials suggests that the diet of N. versicolor consists of ˜60% leaves in terms of biomass, leaving ˜40% for other sources such as animal tissue and benthic microorganisms. The biomass contribution from animal tissues, in form of e.g. other crustaceans and fish carcasses, was found to account for ˜15%. Despite the relative low biomass fraction, animal food sources may contribute with up to half of the nitrogen in the diet of N. versicolor. The quantity of ingested sediment most likely exceeds that of animal tissues. However, due to the low concentration of assimilable microalgae and other microorganism, we propose that sediment associated sources are less important as a nitrogen source for N. versicolor than hitherto presumed.

  1. Correction for the 17O interference in δ(13C) measurements when analyzing CO2 with stable isotope mass spectrometry

    USGS Publications Warehouse

    Coplen, Tyler B.; Brand, Willi A.; Assonov, Sergey S.

    2010-01-01

    Measurements of δ(13C) determined on CO2 with an isotope-ratio mass spectrometer (IRMS) must be corrected for the amount of 17O in the CO2. For data consistency, this must be done using identical methods by different laboratories. This report aims at unifying data treatment for CO2 IRMS by proposing (i) a unified set of numerical values, and (ii) a unified correction algorithm, based on a simple, linear approximation formula. Because the oxygen of natural CO2 is derived mostly from the global water pool, it is recommended that a value of 0.528 be employed for the factor λ, which relates differences in 17O and 18O abundances. With the currently accepted N(13C)/N(12C) of 0.011 180(28) in VPDB (Vienna Peedee belemnite) reevaluation of data yields a value of 0.000 393(1) for the oxygen isotope ratio N(17O)/N(16O) of the evolved CO2. The ratio of these quantities, a ratio of isotope ratios, is essential for the 17O abundance correction: [N(17O)/N(16O)]/[N(13C)/N(12C)] = 0.035 16(8). The equation [δ(13C) ≈ 45δVPDB-CO2 + 2 17R/13R (45δVPDB-CO2 – λ46δVPDB-CO2)] closely approximates δ(13C) values with less than 0.010 ‰ deviation for normal oxygen-bearing materials and no more than 0.026 ‰ in extreme cases. Other materials containing oxygen of non-mass-dependent isotope composition require a more specific data treatment. A similar linear approximation is also suggested for δ(18O). The linear approximations are easy to implement in a data spreadsheet, and also help in generating a simplified uncertainty budget.

  2. A capillary absorption spectrometer for stable carbon isotope ratio (13C/12C) analysis in very small samples

    NASA Astrophysics Data System (ADS)

    Kelly, J. F.; Sams, R. L.; Blake, T. A.; Newburn, M.; Moran, J.; Alexander, M. L.; Kreuzer, H.

    2012-02-01

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO2 samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO2 near 2307 cm-1 (4.34 μm). This initial CAS system can achieve relative isotopic precision of about 10 ppm 13C, or ˜1‰ (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO2 concentrations ˜400-750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to ˜2 Torr. Overall 13C/12C ratios can be calibrated to ˜2‰ accuracy with diluted CO2 standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1000 scans are co-added in ˜10 s. The CAS is meant to work directly with converted CO2 samples from a laser ablation-catalytic combustion micro-sampler to provide 13C/12C ratios of small biological isolates currently operating with spatial resolutions ˜50 μm.

  3. Can 13C stable isotope analysis uncover essential amino acid provisioning by termite-associated gut microbes?

    PubMed Central

    Jones, Susan C.; Sabree, Zakee L.

    2015-01-01

    Gut-associated microbes of insects are postulated to provide a variety of nutritional functions including provisioning essential amino acids (EAAs). Demonstrations of EAA provisioning in insect-gut microbial systems, nonetheless, are scant. In this study, we investigated whether the eastern subterranean termite Reticulitermes flavipes sourced EAAs from its gut-associated microbiota. δ13CEAA data from termite carcass, termite gut filtrate and dietary (wood) samples were determined following 13C stable isotope analysis. Termite carcass samples (−27.0 ± 0.4‰, mean ± s.e.) were significantly different from termite gut filtrate samples (−27.53 ± 0.5‰), but not the wood diet (−26.0 ± 0.5‰) (F(2,64) = 6, P < 0.0052). δ13CEAA-offsets between termite samples and diet suggested possible non-dietary EAA input. Predictive modeling identified gut-associated bacteria and fungi, respectively as potential major and minor sources of EAAs in both termite carcass and gut filtrate samples, based on δ13CEAA data of four and three EAAs from representative bacteria, fungi and plant data. The wood diet, however, was classified as fungal rather than plant in origin by the model. This is attributed to fungal infestation of the wood diet in the termite colony. This lowers the confidence with which gut microbes (bacteria and fungi) can be attributed with being the source of EAA input to the termite host. Despite this limitation, this study provides tentative data in support of hypothesized EAA provisioning by gut microbes, and also a baseline/framework upon which further work can be carried out to definitively verify this function. PMID:26336647

  4. A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples

    SciTech Connect

    Kelly, James F.; Sams, Robert L.; Blake, Thomas A.; Newburn, Matthew K.; Moran, James J.; Alexander, M. L.; Kreuzer, Helen W.

    2012-02-06

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO{sub 2} samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO{sub 2} near 2307 cm{sup -1} (4.34 {mu}m). This initial CAS system can achieve relative isotopic precision of about 10 ppm {sup 13}C, or {approx}1{per_thousand} (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO{sub 2} concentrations {approx}400 to 750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to {approx}2 Torr. Overall {sup 13}C/{sup 12}C ratios can be calibrated to {approx}2{per_thousand} accuracy with diluted CO{sub 2} standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1,000 scans are co-added in {approx}10 sec. The CAS is meant to work directly with converted CO{sub 2} samples from a Laser Ablation-Catalytic-Combustion (LA CC) micro-sampler to provide {sup 13}C/{sup 12}C ratios of small biological isolates with spatial resolutions {approx}50 {mu}m.

  5. The stable isotopic composition of Daphnia ephippia reflects changes in δ13C and δ18O values of food and water

    NASA Astrophysics Data System (ADS)

    Schilder, J.; Tellenbach, C.; Möst, M.; Spaak, P.; van Hardenbroek, M.; Wooller, M. J.; Heiri, O.

    2015-06-01

    The stable isotopic composition of fossil resting eggs (ephippia) of Daphnia spp. is being used to reconstruct past environmental conditions in lake ecosystems. However, the underlying assumption that the stable isotopic composition of the ephippia reflects the stable isotopic composition of the parent Daphnia, of their diet and of the environmental water have yet to be confirmed in a controlled experimental setting. We performed experiments with Daphnia pulicaria cultures, which included a control treatment conducted at 12 °C in filtered lake water and with a diet of fresh algae and three treatments in which we manipulated the stable carbon isotopic composition (δ13C value) of the algae, stable oxygen isotopic composition (δ18O value) of the water and the water temperature, respectively. The stable nitrogen isotopic composition (δ15N value) of the algae was similar for all treatments. At 12 °C, differences in algal δ13C values and in δ18O values of water were reflected in those of Daphnia. The differences between ephippia and Daphnia stable isotope ratios were similar in the different treatments (δ13C: +0.2 ± 0.4 ‰ (standard deviation); δ15N: -1.6 ± 0.4 ‰; δ18O: -0.9 ± 0.4 ‰), indicating that changes in dietary δ13C values and in δ18O values of water are passed on to these fossilizing structures. A higher water temperature (20 °C) resulted in lower δ13C values in Daphnia and ephippia than in the other treatments with the same food source and in a minor change in the difference between δ13C values of ephippia and Daphnia (to -1.3 ± 0.3 ‰). This may have been due to microbial processes or increased algal respiration rates in the experimental containers, which may not affect Daphnia in natural environments. There was no significant difference in the offset between δ18O and δ15N values of ephippia and Daphnia between the 12 and 20 °C treatments, but the δ18O values of Daphnia and ephippia were on average 1.2 ‰ lower at 20 °C than at

  6. Effects of cadmium combined with ultraviolet-B radiation on growth, gas exchange, and stable carbon isotope value (δ13C) in soybean (Glycine max L.)

    NASA Astrophysics Data System (ADS)

    Chen, Tuo; Qiang, Weiya; An, Lizhe; Wang, Xunling

    2003-06-01

    The changes in growth, gas exchange, and stable carbon isotope value (δ13C) in soybean seedlings (Glycine max L. Merr. cv. Longdou No.1) exposed to a 11.2 kJ m-2 day-1 biologically effective UV-B radiation (UV-BBE, 280-315 nm) and 50 mg CdCl2 kg-1 vermicular treatment, either alone or in combination were investigated under greenhouse conditions. Compared to the control, plant height and biomass, photosynthesis rates (Pn), water-use efficiency (WUE), and stomatal conductance (Gs) decreased significantly (P<0.05) exposed to cadmium (Cd) or UV-B radiation and combination. Leaf stable carbon isotope composition (δ13C values) decreased by Cd or UV-B radiation alone and in combination, δ13C were significantly correlated with changes in Pn, WUE and biomass. But Cd and UV-B in combination did not cause greater changes compared to Cd or UV-B radiation alone in many parameters. These results suggested that there was relatively little interaction of the two stresses. δ13C values may provide a reliable indication for growth, WUE, Pn or biomass of soybean seedlings when exposed to UV-B radiation and cadmium pollution.

  7. Effects of Air Pollutants on the Composition of Stable Carbon Isotopes, δ13C, of Leaves and Wood, and on Leaf Injury 1

    PubMed Central

    Martin, Bjorn; Bytnerowicz, Andrzej; Thorstenson, Yvonne R.

    1988-01-01

    Air pollutants are known to cause visible leaf injury as well as impairment of photosynthetic CO2 fixation. Here we evaluate whether the effects on photosynthesis are large enough to cause changes in the relative composition of stable carbon isotopes, δ13C, of plant tissue samples, and, if so, how the changes relate to visual leaf injury. For that purpose, several woody and herbaceous plant species were exposed to SO2 + O3 and SO2 + O3 + NO2 for one month (8 hours per day, 5 days per week). At the end of the fumigations, the plants were evaluated for visual leaf lesions, and δ13C of leaf tissue was determined. Woody plants generally showed less visual leaf injury and smaller effects on δ13C of pollutant exposure than did herbaceous plants. If δ13C was affected by pollutants, it became, with few exceptions, less negative. The data from the fumigation experiments were consistent with δ13C analyses of whole wood of annual growth rings from two conifer tree species, Pseudotsuga menziesii and Pinus strobus. These trees had been exposed until 1977 to exhaust gases from a gas plant at Lacq, France. Wood of both conifer species formed in the polluted air of 1972 to 1976 had less negative δ13C values than had wood formed in the much cleaner air in 1982 to 1986. No similar, time-dependent differences in δ13C of wood were observed in trees which had been continuously growing in clean air. Our δ13C data from both relatively short-term artificial exposures and long-term natural exposure are consistent with greater stomatal limitation of photosynthesis in polluted air than in clean air. PMID:16666270

  8. Tracking spatial distribution of human-derived wastewater from Davis Station, East Antarctica, using δ15N and δ13C stable isotopes.

    PubMed

    Corbett, Patricia A; King, Catherine K; Mondon, Julie A

    2015-01-15

    Stable isotope ratios, δ15N and δ13C were effectively used to determine the geographical dispersion of human derived sewage from Davis Station, East Antarctica, using Antarctic rock cod (Trematomus bernacchii). Fish within 0-4 km downstream of the outfall exhibited higher δ15N and δ13C values relative to reference sites. Nitrogen in particular showed a stepped decrease in δ15N with increasing distance from the discharge point by 1-2‰. Stable isotopes were better able to detect the extent of wastewater contamination than other techniques including faecal coliform and sterol measures. Uptake and assimilation of δ15N and δ13C up to 4 km from the outfall adds to growing evidence indicating the current level of wastewater treatment at Davis Station is not sufficient to avoid impact to the surrounding environment. Isotopic assimilation in T. bernacchii is a viable biomarker for investigation of initial sewage exposure and longer term monitoring in the future. PMID:25487089

  9. Stable Oxygen (δ 18O) and Carbon (δ 13C) Isotopes in the Skeleton of Bleached and Recovering Corals From Hawaii

    NASA Astrophysics Data System (ADS)

    Rodrigues, L. J.; Grottoli, A. G.

    2004-12-01

    Coral skeletal stable oxygen isotopes (δ 18O) reflect changes in seawater temperature and salinity, while stable carbon isotopes13C) reflect a combination of both metabolic (photosynthesis and feeding) and kinetic fractionation. Together, the two isotopic signatures may be used as a proxy for past bleaching events. During bleaching, increased seawater temperatures often contribute to a decline in zooxanthellae and/or chlorophyll concentrations, resulting in a decrease in photosynthesis. We experimentally investigated the effect of bleaching and subsequent recovery on the δ 13C and δ 18O values of coral skeleton. Fragments from two coral species (Montipora capitata and Porites compressa) from Kaneohe Bay, Hawaii were bleached in outdoor tanks by raising the seawater temperature to 30° C. Additional fragments from the same parent colonies were maintained at ambient seawater temperatures (27° C) in separate tanks as controls. After one month in the tanks, a subset of the fragments was frozen and all remaining fragments were placed back on the reef to recover. All coral fragments were analyzed for their skeletal δ 13C and δ 18O compositions at five time intervals: before, immediately after, 1.5, 4, and 8 months after bleaching. In addition, rates of photosynthesis, calcification, and heterotrophy were also measured. Immediately after bleaching, δ 18O decreased in bleached M. capitata relative to controls, reflecting their exposure to increased seawater temperatures. During recovery, δ 18O values in the treatment M. capitata were not different from the controls. In P. compressa, δ 18O did not significantly differ in bleached and control corals at any time during the experiment. Immediately after bleaching, δ 13C decreased in the bleached fragments of both species relative to controls reflecting decreased photosynthetic rates. However, during recovery δ 13C in both species was greater in bleached than control fragments despite photosynthesis remaining

  10. Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ13C and δ15N)

    PubMed Central

    Nelson, James A.; Rozar, Katherine L.; Adams, Charles S.; Wall, Kara R.; Switzer, Theodore S.; Winner, Brent L.; Hollander, David J.

    2015-01-01

    Research that uses stable isotope analysis often involves a delay between sample collection in the field and laboratory processing, therefore requiring preservation to prevent or reduce tissue degradation and associated isotopic compositions. Although there is a growing literature describing the effects of various preservation techniques, the results are often contextual, unpredictable and vary among taxa, suggesting the need to treat each species individually. We conducted a controlled experiment to test the effects of four preservation methods of muscle tissue from four species of upper trophic-level reef fish collected from the eastern Gulf of Mexico (Red Grouper Epinephelus morio, Gag Mycteroperca microlepis, Scamp Mycteroperca phenax, and Red Snapper Lutjanus campechanus). We used a paired design to measure the effects on isotopic values for carbon and nitrogen after storage using ice, 95% ethanol, and sodium chloride (table salt), against that in a liquid nitrogen control. Mean offsets for both δ13C and δ15N values from controls were lowest for samples preserved on ice, intermediate for those preserved with salt, and highest with ethanol. Within species, both salt and ethanol significantly enriched the δ15N values in nearly all comparisons. Ethanol also had strong effects on the δ13C values in all three groupers. Conversely, for samples preserved on ice, we did not detect a significant offset in either isotopic ratio for any of the focal species. Previous studies have addressed preservation-induced offsets in isotope values using a mass balance correction that accounts for changes in the isotope value to that in the C/N ratio. We tested the application of standard mass balance corrections for isotope values that were significantly affected by the preservation methods and found generally poor agreement between corrected and control values. The poor performance by the correction may have been due to preferential loss of lighter isotopes and corresponding

  11. Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ (13)C and δ (15)N).

    PubMed

    Stallings, Christopher D; Nelson, James A; Rozar, Katherine L; Adams, Charles S; Wall, Kara R; Switzer, Theodore S; Winner, Brent L; Hollander, David J

    2015-01-01

    Research that uses stable isotope analysis often involves a delay between sample collection in the field and laboratory processing, therefore requiring preservation to prevent or reduce tissue degradation and associated isotopic compositions. Although there is a growing literature describing the effects of various preservation techniques, the results are often contextual, unpredictable and vary among taxa, suggesting the need to treat each species individually. We conducted a controlled experiment to test the effects of four preservation methods of muscle tissue from four species of upper trophic-level reef fish collected from the eastern Gulf of Mexico (Red Grouper Epinephelus morio, Gag Mycteroperca microlepis, Scamp Mycteroperca phenax, and Red Snapper Lutjanus campechanus). We used a paired design to measure the effects on isotopic values for carbon and nitrogen after storage using ice, 95% ethanol, and sodium chloride (table salt), against that in a liquid nitrogen control. Mean offsets for both δ (13)C and δ (15)N values from controls were lowest for samples preserved on ice, intermediate for those preserved with salt, and highest with ethanol. Within species, both salt and ethanol significantly enriched the δ (15)N values in nearly all comparisons. Ethanol also had strong effects on the δ (13)C values in all three groupers. Conversely, for samples preserved on ice, we did not detect a significant offset in either isotopic ratio for any of the focal species. Previous studies have addressed preservation-induced offsets in isotope values using a mass balance correction that accounts for changes in the isotope value to that in the C/N ratio. We tested the application of standard mass balance corrections for isotope values that were significantly affected by the preservation methods and found generally poor agreement between corrected and control values. The poor performance by the correction may have been due to preferential loss of lighter isotopes and

  12. The response of the foliar antioxidant system and stable isotopes (δ(13)C and δ(15)N) of white willow to low-level air pollution.

    PubMed

    Wuytack, Tatiana; AbdElgawad, Hamada; Staelens, Jeroen; Asard, Han; Boeckx, Pascal; Verheyen, Kris; Samson, Roeland

    2013-06-01

    In this study we aimed to determine and elucidate the effect of ambient air pollution on the foliar antioxidant system and stable carbon and nitrogen isotopes of white willow (Salix alba L.). We grew white willow in uniform potting soil in the near vicinity of sixteen air quality monitoring stations in Belgium where nitrogen dioxide (NO2), ozone, sulfur dioxide and particulate matter concentrations were continuously measured. The trees were exposed to ambient air during six months (April-September 2011), and, thereafter, the degree of lipid peroxidation and foliar content of antioxidant molecules (ascorbate, glutathione, polyphenols, flavonoids), antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, peroxidase) and foliar stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes were measured. We found that lipid peroxidation was caused by air pollution stress, arising from high ambient NO2 concentrations, as shown by an increased amount of malondialdehyde. The antioxidant system was activated by increasing the amount of polyphenols at monitoring stations with a high atmospheric NO2 and low O3 concentration, while no increase of key enzymes (e.g., ascorbate, glutathione) was observed. The δ(13)C also decreased with increasing NO2 concentrations and decreasing O3 concentrations, probably reflecting a decreased net photosynthesis and/or a concomitant decrease of (13)CO2 in the atmosphere. Shade also influenced foliar δ(13)C and the content of leaf ascorbate and glutathione. PMID:23562799

  13. Sensitive, Efficient Quantitation of 13C-Enriched Nucleic Acids via Ultrahigh-Performance Liquid Chromatography–Tandem Mass Spectrometry for Applications in Stable Isotope Probing

    PubMed Central

    Wilhelm, Roland; Szeitz, András; Klassen, Tara L.

    2014-01-01

    Stable isotope probing (SIP) of nucleic acids is a powerful tool for studying the functional traits of microbial populations within complex communities, but SIP involves a number of technical challenges. Many of the difficulties in DNA-SIP and RNA-SIP experiments can be effectively overcome with an efficient, sensitive method for quantitating the isotopic enrichment of nucleic acids. Here, we present a sensitive method for quantitating 13C enrichment of nucleic acids, requiring a few nanograms of sample, and we demonstrate its utility in typical DNA-SIP and RNA-SIP experiments. All five nucleobases (adenine, guanine, cytosine, thymine, and uracil) were separated and detected by using ultrahigh-performance liquid chromatography–tandem mass spectrometry. We detected all isotopic species in samples with as low as 1.5 atom% 13C above natural abundance, using 1-ng loadings. Quantitation was used to characterize the isotopic enrichment kinetics of cellulose- and lignin-based microcosm experiments and to optimize the recovery of enriched nucleic acids. Application of our method will minimize the quantity of expensive isotopically labeled substrates required and reduce the risk of failed experiments due to insufficient recovery of labeled nucleic acids for sequencing library preparation. PMID:25217022

  14. UV-laser microdissection system - A novel approach for the preparation of high-resolution stable isotope records (δ13C/δ18O) from tree rings

    NASA Astrophysics Data System (ADS)

    Schollaen, Karina; Helle, Gerhard

    2013-04-01

    Intra-annual stable isotope13C and δ18O) studies of tree rings at various incremental resolutions have been attempting to extract valuable seasonal climatic and environmental information or assessing plant ecophysiological processes. For preparing high-resolution isotope samples normally wood segments or cores are mechanically divided in radial direction or cut in tangential direction. After mechanical dissection, wood samples are ground to a fine powder and either cellulose is extracted or bulk wood samples are analyzed. Here, we present a novel approach for the preparation of high-resolution stable isotope records from tree rings using an UV-laser microdissection system. Firstly, tree-ring cellulose is directly extracted from wholewood cross-sections largely leaving the wood anatomical structure intact and saving time as compared to the classical procedure. Secondly, micro-samples from cellulose cross-sections are dissected with an UV-Laser dissection microscope. Tissues of interest from cellulose cross-sections are identified and marked precisely with a screen-pen and dissected via an UV-laser beam. Dissected cellulose segments were automatically collected in capsules and are prepared for stable isotope13C and δ18O) analysis. The new techniques facilitate inter- and intra-annual isotope analysis on tree-ring and open various possibilities for comparisons with wood anatomy in plant eco-physiological studies. We describe the design and the handling of this novel methodology and discuss advantages and constraints given by the example of intra-annual oxygen isotope analysis on tropical trees.

  15. Feeding and migration habits of white shark Carcharodon carcharias (Lamniformes: Lamnidae) from Isla Guadalupe inferred by analysis of stable isotopes delta15N and delta13C.

    PubMed

    Jaime-Rivera, Mario; Caraveo-Patiño, Javier; Hoyos-Padilla, Mauricio; Galván-Magaña, Felipe

    2014-06-01

    Stable isotope composition of marine top predator's tissues provides insight information of its trophic ecology and migratory behavior. Previous reports have shown that dermal tissues could record longer patterns of hunting and movement. Based on this, the aim of this study was to describe the feeding and migratory habits of the white shark from Isla Guadalupe, using stable isotopic analysis of dermis. We considered a small subset of many possible prey taxa that the sharks could have eaten throughout their migration: pinnipeds, squid and tuna. We grouped the data in five focal areas: Gulf of California, Coast of California, Isla Guadalupe, SOFA and Hawaii. We performed a Bayesian mixing model to study the trophic ecology of this top predator. Average isotopic values for dermis tissue of white shark were delta13C (-14.5 per thousand) and delta15N (19.1 per thousand). Corrected white shark dermal mean values to resemble muscle were delta13C (-16.6 per thousand) and delta15N (21.2 per thousand). Mixing model data from dermis showed predation in offshore areas such the SOFA and a main importance of pinnipeds as prey of the white shark in Isla Guadalupe. PMID:25102646

  16. [Carbon stable isotope composition (delta 13C) of lichen thalli in the forests in the vicinity of the Chernobyl atomic power station].

    PubMed

    Biazrov, L G; Gongal'skiĭ, K B; Pel'gunova, L A; Tiunov, A V

    2010-01-01

    The stable isotope abundance of carbon in the lichens Cladina mitis, Cladonia crispata Hypogymnia physodes, Parmelia sulcata has been investigated in a study relating these values with known levels of 106Ru, 134Cs, 137Cs and 144Ce defined activity in their thalli in the pine forests of region within a 30-km radius of the Chernobyl atomic power station and beyond it (37 km). All 63 samples of the lichens were obtained from 7 different sites. Small effects on delta 13C values in the lichens Cladina mitis, Hypogymnia physodes were found to be associated with distance from CNPP, activity level of radionuclides in them thalli whereas at Cladonia crispata is observed weighting of carbon with increase in values of 134Cs and 137Cs activity in thalli. Values of delta 13C the investigated lichen species more depends on habitat conditions rather than from levels of thalli radioactivity. In our study we didn't reveal the isotope specificity of any one species as it was not possible to establish a correlation between values of delta 13C and a particular species. PMID:20297687

  17. Trophic ecology of the supralittoral rocky shore (Roscoff, France): A dual stable isotope13C, δ 15N) and experimental approach

    NASA Astrophysics Data System (ADS)

    Laurand, Sandrine; Riera, Pascal

    2006-07-01

    The present study investigates the trophic transfers on the upper littoral rocky shore (i.e. the supralittoral zone together with the upper midlittoral and adlittoral) of northern Brittany. The population mainly consists of four invertebrate species: the littorinids Littorina saxatilis and Melarhaphe neritoides, the isopod Ligia oceanica and the insect Petrobius maritimus. The utilisation of food sources available to these grazers was examined in a laboratory microcosm feeding experiment and a field study using stable isotopes13C, δ 15N). The results indicated that although Ligia oceanica preferentially occurs in the supralittoral zone, its trophic subsidies originate mostly from the adlittoral and lower intertidal zones. The stable isotope data also suggested that adlittoral terrestrial organic material may be the major food source of Petrobius maritimus. δ 15N of Littorina saxatilis indicated a highly variable diet consisting of supralittoral lichens, midlittoral macroalgae and other food sources (e.g. microalgae). Both feeding experiments and stable isotope data show that only Melarhaphe neritoides has a clearly identifiable diet based on a mixture of lichens, mostly Verrucaria maura and Caloplaca marina, as estimated by an isotopic mixing model. Hence, the food web of this intertidal zone appears largely based on trophic subsidies from other habitats (i.e. upper and lower intertidal zones).

  18. Application of (13)C and (15)N stable isotope probing to characterize RDX degrading microbial communities under different electron-accepting conditions.

    PubMed

    Cho, Kun-Ching; Lee, Do Gyun; Fuller, Mark E; Hatzinger, Paul B; Condee, Charles W; Chu, Kung-Hui

    2015-10-30

    This study identified microorganisms capable of using the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) or its metabolites as carbon and/or nitrogen sources under different electron-accepting conditions using (13)C and (15)N stable isotope probing (SIP). Mesocosms were constructed using groundwater and aquifer solids from an RDX-contaminated aquifer. The mesocosms received succinate as a carbon source and one of four electron acceptors (nitrate, manganese(IV), iron(III), or sulfate) or no additional electron acceptor (to stimulate methanogenesis). When RDX degradation was observed, subsamples from each mesocosm were removed and amended with (13)C3- or ring-(15)N3-, nitro-(15)N3-, or fully-labeled (15)N6-RDX, followed by additional incubation and isolation of labeled nucleic acids. A total of fifteen 16S rRNA sequences, clustering in α- and γ-Proteobacteria, Clostridia, and Actinobacteria, were detected in the (13)C-DNA fractions. A total of twenty seven sequences were derived from different (15)N-DNA fractions, with the sequences clustered in α- and γ-Proteobacteria, and Clostridia. Interestingly, sequences identified as Desulfosporosinus sp. (in the Clostridia) were not only observed to incorporate the labeled (13)C or (15)N from labeled RDX, but also were detected under each of the different electron-accepting conditions. The data suggest that (13)C- and (15)N-SIP can be used to characterize microbial communities involved in RDX biodegradation, and that the dominant pathway of RDX biodegradation may differ under different electron-accepting conditions. PMID:25935409

  19. Experimental assessment of the purity of α-cellulose produced by variations of the Brendel method: Implications for stable isotope13C, δ18O) dendroclimatology

    NASA Astrophysics Data System (ADS)

    Brookman, Tom; Whittaker, Thomas

    2012-09-01

    Stable isotope dendroclimatology using α-cellulose has unique potential to deliver multimillennial-scale, sub-annually resolved, terrestrial climate records. However, lengthy processing and analytical methods often preclude such reconstructions. Variants of the Brendel extraction method have reduced these limitations, providing fast, easy methods of isolating α-cellulose in some species. Here, we investigate application of Standard Brendel (SBrendel) variants to resinous soft-woods by treating samples of kauri (Agathis australis), ponderosa pine (Pinus ponderosa) and huon pine (Lagarastrobus franklinii), varying reaction vessel, temperature, boiling time and reagent volume. Numerous samples were visibly `under-processed' and Fourier Transform infrared spectroscopic (FTIR) investigation showed absorption peaks at 1520 cm-1 and ˜1600 cm-1 in those fibers suggesting residual lignin and retained resin respectively. Replicate analyses of all samples processed at high temperature yielded consistent δ13C and δ18O despite color and spectral variations. Spectra and isotopic data revealed that α-cellulose δ13C can be altered during processing, most likely due to chemical contamination from insufficient acetone removal, but is not systematically affected by methodological variation. Reagent amount, temperature and extraction time all influence δ18O, however, and our results demonstrate that different species may require different processing methods. FTIR prior to isotopic analysis is a fast and cost effective way to determine α-cellulose extract purity. Furthermore, a systematic isotopic test such as we present here can also determine sensitivity of isotopic values to methodological variables. Without these tests, isotopic variability introduced by the method could obscure or `create' climatic signals within a data set.

  20. A mass spectrometric method for measuring glycerol levels and enrichments in plasma using 13C and 2H stable isotopic tracers.

    PubMed

    Gilker, C D; Pesola, G R; Matthews, D E

    1992-08-15

    The stable isotope tracer [1,1,2,3,3,-2H5]glycerol has been commonly used as a tracer to measure glycerol kinetics and lipolysis in vivo. The method for measuring samples using the trimethylsilyl derivative and electron impact gas chromatograph-mass spectrometry retains only three of the five deuteriums, resulting in the possibility of incorrectly identifying the whole glycerol tracer molecule. This reports preparation of glycerol as the heptafluorobutyrl derivative and measurement by negative ion chemical ionization gas chromatography-mass spectrometry to produce a derivative with an intense molecular ion that retains all five deuterium labels. Thus the heptafluorobutyrl derivative analyzed by negative ion mass spectrometry overcomes the problems associated with fragmentation and loss of the isotopic label. Glycerol concentration using a labeled internal standard can be determined in plasma with a precision of 3%. Nanomole amounts of glycerol can be analyzed for 13C or 2H enrichments with a precision of +/- 0.14 mol% excess isotope. This simple, sensitive method for measuring glycerol levels and stable isotopic enrichment in plasma uses a simple extraction procedure and requires a minimal volume of plasma (less than 300 microliters). PMID:1443555

  1. A mantle origin for Paleoarchean peridotitic diamonds from the Panda kimberlite, Slave Craton: Evidence from 13C-, 15N- and 33,34S-stable isotope systematics

    NASA Astrophysics Data System (ADS)

    Cartigny, Pierre; Farquhar, James; Thomassot, Emilie; Harris, Jeffrey W.; Wing, Bozwell; Masterson, Andy; McKeegan, Kevin; Stachel, Thomas

    2009-11-01

    In order to address diamond formation and origin in the lithospheric mantle underlying the Central Slave Craton, we report N- and C-stable isotopic compositions and N-contents and aggregation states for 85 diamonds of known paragenesis (73 peridotitic, 8 eclogitic and 4 from lower mantle) from the Panda kimberlite (Ekati Mine, Lac de Gras Area, Canada). For 12 peridotitic and two eclogitic sulfide inclusion-bearing diamonds from this sample set, we also report multiple-sulfur isotope ratios. The 73 peridotitic diamonds have a mean δ13C-value of - 5.2‰ and range from - 6.9 to - 3.0‰, with one extreme value at - 14.1‰. The associated δ15N-values range from - 17.0 to + 8.5‰ with a mean value of - 4.0‰. N-contents range from 0 to 1280 ppm. The 8 eclogitic diamonds have δ13C-values ranging from - 11.2 to - 4.4‰ with one extreme value at - 19.4‰. Their δ15N ranges from - 2.1 to + 7.9‰ and N-contents fall between 0 and 3452 ppm. Four diamonds with an inferred lower mantle origin are all Type II (i.e. nitrogen-free) and have a narrow range of δ13C values, between - 4.5 and - 3.5‰. The δ34S of the 14 analyzed peridotitic and eclogitic sulfide inclusions ranges from - 3.5 to +5.7‰. None of them provide evidence for anomalous δ33S-values; observed variations in δ33S are from +0.19 to - 0.33‰, i.e. within the 2 sigma uncertainties of mantle sulfur ( δ33S = 0‰). At Panda, the N contents and the δ13C of sulfide-bearing peridotitic diamonds show narrower ranges than silicate-bearing peridotitic diamonds. This evidence supports the earlier suggestion established from eclogitic diamonds from the Kaapvaal that sulfide-(±silicate) bearing diamonds sample a more restricted portion of sublithospheric mantle than silicate-(no sulfide) bearing diamonds. Our findings at Panda suggest that sulfide-bearing diamonds should be considered as a specific diamond population on a global-scale. Based on our study of δ34S, Δ 33S, δ15N and δ13C, we find no

  2. Trace elements and stable isotopes (delta13C and delta15N) in shallow and deep-water organisms from the East China Sea.

    PubMed

    Asante, Kwadwo Ansong; Agusa, Tetsuro; Mochizuki, Hiroko; Ramu, Karri; Inoue, Suguru; Kubodera, Tsunemi; Takahashi, Shin; Subramanian, Annamalai; Tanabe, Shinsuke

    2008-12-01

    Trace elements (22) and stable isotope ratios (delta15N and delta13C) were analyzed in marine organisms from shallow (SW) and deep-water (DW) of the East China Sea to understand biomagnification and prey source of trace elements. In the benthic marine organisms from DW, delta15N values were negatively correlated with Ba, Cu, Ag, Mo, Sr, As, and Co concentrations. This may be due to the specific accumulation in lower trophic animals and/or the biodilution through the food web in DW. Relationships between delta15N and concentrations of Co, Cr, Bi, and Tl in fish and Ag, Bi, V, Hg, and Tl in crustaceans showed positive correlations, suggesting that trophic position was affecting the concentrations of those elements in phyla, with higher trophic animals retaining higher concentrations than the lower trophic animals. Positive correlations between delta13C and Rb were observed in marine organisms. Therefore, Rb may be a possible substitute of delta13C as tracer of prey source in the East China Sea although further investigation is required. PMID:18583004

  3. Identification of Metabolically Active Bacteria in the Gut of the Generalist Spodoptera littoralis via DNA Stable Isotope Probing Using 13C-Glucose

    PubMed Central

    Boland, Wilhelm

    2013-01-01

    Guts of most insects are inhabited by complex communities of symbiotic nonpathogenic bacteria. Within such microbial communities it is possible to identify commensal or mutualistic bacteria species. The latter ones, have been observed to serve multiple functions to the insect, i.e. helping in insect reproduction1, boosting the immune response2, pheromone production3, as well as nutrition, including the synthesis of essential amino acids4, among others.     Due to the importance of these associations, many efforts have been made to characterize the communities down to the individual members. However, most of these efforts were either based on cultivation methods or relied on the generation of 16S rRNA gene fragments which were sequenced for final identification. Unfortunately, these approaches only identified the bacterial species present in the gut and provided no information on the metabolic activity of the microorganisms. To characterize the metabolically active bacterial species in the gut of an insect, we used stable isotope probing (SIP) in vivo employing 13C-glucose as a universal substrate. This is a promising culture-free technique that allows the linkage of microbial phylogenies to their particular metabolic activity. This is possible by tracking stable, isotope labeled atoms from substrates into microbial biomarkers, such as DNA and RNA5. The incorporation of 13C isotopes into DNA increases the density of the labeled DNA compared to the unlabeled (12C) one. In the end, the 13C-labeled DNA or RNA is separated by density-gradient ultracentrifugation from the 12C-unlabeled similar one6. Subsequent molecular analysis of the separated nucleic acid isotopomers provides the connection between metabolic activity and identity of the species. Here, we present the protocol used to characterize the metabolically active bacteria in the gut of a generalist insect (our model system), Spodoptera littoralis (Lepidoptera, Noctuidae). The phylogenetic analysis of the DNA

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

    PubMed

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

    2016-05-01

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

  5. Importance of bacterivory and preferential selection toward diatoms in larvae of Crepidula fornicata (L.) assessed by a dual stable isotope (13C, 15N) labeling approach

    NASA Astrophysics Data System (ADS)

    Leroy, Fanny; Riera, Pascal; Jeanthon, Christian; Edmond, Frédérique; Leroux, Cédric; Comtet, Thierry

    2012-05-01

    In Europe, the gastropod Crepidula fornicata is an invasive species characterized by a long reproductive period (from February to November). Thus, its larvae are exposed to variations in available food sources (in terms of quantity and quality). We aimed to investigate if bacteria could contribute to larval food both in presence or absence of phytoplankton, and to compare these results to seasonal variations of bacteria and phytoplankton abundances at a coastal site in the English Channel. First, ingestion of fluorescent beads of 0.5 to 2 μm diameter, showed that larvae were able to ingest particles of typical bacterial size. Then we used a dual stable isotope labeling approach which consisted in labeling a bacterial pelagic community with 15N and a diatom (Chaetoceros gracilis) culture with 13C, and supplying larvae with 15N-labeled bacteria, 13C-labeled diatoms, and both labeled sources. This technique has, to our knowledge, never been applied to invertebrate larvae. After 24 h of experiment, larvae were significantly enriched in all treatments: + 21.5‰ (∆δ13C) when supplied with diatoms, + 1364‰ (∆δ15N) when supplied with bacteria, and + 24‰ (∆δ13C) and + 135‰ (∆δ15N) when supplied with the two mixed sources. These results indicated that bacteria can contribute to the larval nutrition in C. fornicata, even in the presence of phytoplankton. Our results however suggested that larvae of C. fornicata preferentially used diatoms and showed that the supply of free bacteria did not alter the uptake of diatoms. Considering the seasonal variations of bacteria and phytoplankton abundances at the study site, these results suggested that bacteria may constitute a complementary resource for the larvae of C. fornicata when phytoplankton is abundant and may become a substitute resource when phytoplankton is less available. This approach offers promising perspectives to trace food sources and assess nitrogen and carbon fluxes between planktotrophic larvae

  6. Stable isotope values (δ18O & δ13C) of multiple ostracode species in a large Neotropical lake as indicators of past changes in hydrology

    NASA Astrophysics Data System (ADS)

    Pérez, Liseth; Curtis, Jason; Brenner, Mark; Hodell, David; Escobar, Jaime; Lozano, Socorro; Schwalb, Antje

    2013-04-01

    Modern lake hydrodynamics, ostracode species autecology, stable isotopes (δ18O and δ13C) of multiple ostracode species, ostracode taphonomy and sediment geochemistry were studied to improve interpretation of the late Pleistocene-early Holocene (˜24-10 ka) stable isotope record of ostracodes in sediment core PI-6 from Lago Petén Itzá, northern Guatemala. Oxygen and carbon stable isotopes in modern and fossil species assemblages of Lago Petén Itzá were used as indicators of changes in the balance between evaporation and precipitation, past lake level and carbon source. Ostracode taphonomy was used to detect past periods of strong currents, high-energy environments, and possible partial or full mixing of the lake. The modern lake water isotopic composition displays clear seasonal differences that are independent of lake level fluctuations. Modern benthic species displayed lower δ18O and δ13C values than nektobenthic species, with differences of 3.0‰ and 5.3‰, respectively. Valves of nektobenthic species display higher values of δ13C because these ostracodes live in shallower environments among abundant algae and aquatic plants, where productivity is high. The benthic species Limnocythere opesta Brehm, 1939 displayed the smallest average offset from δ18O water (+0.3‰) and the largest offset from δ13CDIC values (-4.1‰) among studied ostracode species. Nektobenthic species Heterocypris punctata Keyser, 1975 displayed the smallest difference relative to the δ13CDIC values (-0.1‰). Late Pleistocene-early Holocene climate conditions and water levels in Lago Petén Itzá can be summarized as follows: 1) high lake levels and cold conditions (Last Glacial Maximum [LGM], ˜24-19 ka), 2) fluctuating lake levels and cold conditions (Heinrich Stadial 1 [HS1], ˜19-15 ka), 3) high lake levels and warm and wetter conditions (Bølling-Allerød [BA], ˜15-13 ka), 4) low lake levels and dry conditions (Younger Dryas [YD], ˜13-11.5 ka) and 5) high lake levels and

  7. Assessment of trace elements, POPs, (210)Po and stable isotopes ((15)N and (13)C) in a rare filter-feeding shark: The megamouth.

    PubMed

    Moura, Jailson Fulgencio de; Merico, Agostino; Montone, Rosalinda Carmela; Silva, Josilene; Seixas, Tércia Guedes; Godoy, José Marcus de Oliveira; Saint'Pierre, Tatiana Dillenburg; Hauser-Davis, Rachel Ann; Di Beneditto, Ana Paula Madeira; Reis, Estéfane Cardinot; Tavares, Davi Castro; Lemos, Leila Soledade; Siciliano, Salvatore

    2015-06-15

    With less than 60 records being reported worldwide, the megamouth (Megachasma pelagios) is today one of the least known shark species inhabiting our oceans. Therefore, information concerning the biology and ecology of this enigmatic organism is very scarce and limited to feeding behaviour and preferred habitat. The present work reports new data on the concentrations of trace elements, organic mercury, POPs and (210)Po in hepatic and muscular tissues of a specimen found stranded in the southeastern coast of Brazil. Additionally, we provide new evidence based on stable isotope analysis (δ(15)N and δ(13)C) confirming the preference for the pelagic habitat and the zooplanktivorous feeding behaviour of the megamouth. These results are consistent with the low concentrations of organic pollutant compounds and other elements measured in our samples. PMID:25858662

  8. Stable Isotope13C, δ15N, δ34S) Analysis and Satellite Telemetry Depict the Complexity of Gray Wolf (Canis lupus) Diets in Southwest Alaska

    NASA Astrophysics Data System (ADS)

    Stanek, A.; Watts, D. E.; Cohn, B. R.; Spencer, P.; Mangipane, B.; Welker, J. M.

    2010-12-01

    Throughout Alaska, gray wolves (Canis lupus) are a top predator of large ungulates. While they primarily rely on ungulates such as moose (Alces alces) and caribou (Rangifer tarandus) as food, they are opportunistic and use alternative resources. The variation and supplemental protein sources in wolf diet has not been studied extensively on live animals currently using the landscape. With large seasonal influxes of Pacific salmon (Oncorhynchus sp.) into Alaska, terrestrial carnivore use of marine species is of particular interest. Using stable isotope13C, δ15N, δ34S) analysis of wolf guard hair and blood, this study aims to determine the proportion of marine derived nutrients (MDN) in the diet of wolf packs within and surrounding Lake Clark National Park and Preserve and Alaska Peninsula and Becharof National Wildlife Refuges in Southwest Alaska. Satellite telemetry from the animals sampled facilitates quantification of landscape use patterns in correspondence with isotopic traits. Wolf pack territories within and surrounding the Lake Clark region appear to vary in spatial extent and in availability of MDN, such as salmon. Initial analysis shows that two packs with smaller home ranges, centrally located around areas with greater salmon availability, have enriched δ15N values compared to packs that have larger home ranges not centralized around salmon spawning waters. This pattern of isotopic enrichment is found in red blood cells, blood serum and hair, representing diets over different time scales. The enrichment in both blood and hair indicates a sustained use of MDN over the previous six to nine months. In the Lake Clark region, simple mixing model estimates suggest that up to 30% of wolf pack diets may be from marine sources. In contrast, packs with larger home ranges and less access to salmon have stable isotope values representative of a terrestrial diet.

  9. Carbon (δ13C) and Nitrogen (δ15N) Stable Isotope Signatures in Bat Fur Indicate Swarming Sites Have Catchment Areas for Bats from Different Summering Areas

    PubMed Central

    Segers, Jordi L.; Broders, Hugh G.

    2015-01-01

    Migratory patterns of bats are not well understood and traditional methods to study this, like capture-mark-recapture, may not provide enough detail unless there are many records. Stable isotope profiles of many animal species have been used to make inferences about migration. Each year Myotis lucifugus and M. septentrionalis migrate from summering roosts to swarming caves and mines in the fall, but the pattern of movement between them is not well understood. In this study, fur δ13C and δ15N values of 305 M. lucifugus and 200 M. septentrionalis were analyzed to make inferences about migration patterns between summering areas and swarming sites in Nova Scotia, Canada. We expected that there would be greater variability in δ13C and δ15N among individuals at swarming sites because it was believed that these sites are used by individuals originating from many summering areas. There was extensive overlap in the standard ellipse area, corrected for small sample sizes (SEAc), of bats at swarming sites and much less overlap in SEAc among groups sampled at summering areas. Meaningful inference could not be made on M. septentrionalis because their low variation in SEAc may have been the result of sampling only 3 summering areas. However, for M. lucifugus, swarming sites had larger SEAc than summering areas and predictive discriminant analysis assigned swarming bats to multiple summering areas, supporting the contention that swarming bats are mixed aggregations of bats from several summering areas. Together, these data support the contention that swarming sites have catchment areas for bats from multiple summering areas and it is likely that the catchment areas for swarming sites overlap. These data suggest that δ13C and δ15N profiling of bat fur offer some potential to make inferences about regional migration in bats. PMID:25923696

  10. Benthic macroinvertebrates and the use of stable isotopes13C and δ15N) in the impact assessment of peatland use on boreal stream ecosystems

    NASA Astrophysics Data System (ADS)

    Nieminen, Mika L.; Daza Secco, Emmanuela; Nykänen, Hannu; Meissner, Kristian

    2013-04-01

    Stable isotope analysis (SIA) can provide insights into carbon flow dynamics and trophic positions of consumers in food webs. SIA is used in this study, where we assess the possible changes in the basal resources of Finnish boreal stream ecosystems and differences in the impact of two forms of peatland use, forestry and peat mining. About 30% of the total land area of Finland is classified as peatland, of which about 55% has been drained for forestry and about 0.6% is in peat production. Unlike forestry, peat production is regionally less scattered and can thus have measurable local impacts although the total area of peat production is small. Three watersheds were used as study areas. Within each watershed, one stream drains a subcatchment affected only by peat mining, whereas the other stream flows through a subcatchment affected by forestry. The two subcatchment streams merge to form a single stream flowing into a lake. Studied watersheds were subject to no other forms of land use. In addition to the impacted sites, we used two pristine natural mire and two natural forest catchments as controls. We analysed the stable isotopes of carbon (δ13C) and nitrogen (δ15N) from benthic macroinvertebrates, stream bank soil, stream sediment, and dissolved organic carbon (DOC) in stream water. Samples for stable isotope analyses were collected in the summer of 2011 and samples for invertebrate community analyses in the autumn of 2011. Upon sampling we measured several physical parameters at each sampling site. In addition, stream water samples collected in summer and autumn 2012 were analysed for CH4 and CO2 gas concentrations and autumn gas samples also for their δ13C values. Our initial SIA results of invertebrates suggest some degree of discrimination between different sources of OM and possible effects on feeding habits, presumably due to the quality of the basal resources. We will explore this result further by examining not only taxonomical structure, but also the

  11. Early life histories of the London poor using δ13C and δ15N stable isotope incremental dentine sampling.

    PubMed

    Henderson, Rowena C; Lee-Thorp, Julia; Loe, Louise

    2014-08-01

    High resolution incremental isotopic analysis of the dentine from early forming teeth, especially first molars (M1s), provides a means to assess the effects of poor childhood nutrition and healthcare on individuals in an assemblage where there are no infants to study. This approach is applied to an 18th and 19th century cemetery population associated with St Saviour's Almshouse burial ground in Southwark, London, to assess whether, or how, early dietary history, including weaning age, influenced health and nutritional status. The results show a general pattern in which non-breast milk foods were introduced before or by 6 months of age, as indicated by elevated δ(15) N during this period. Almost all individuals for which we also have second molar (M2) records, showed lower δ(15) N values from a very young age (>1 year) until approximately 8-10 years, compared to adult values. The overall results show a significant difference in δ(1) (3) C (p = 0 to 4sf, F = 17.327) and a weaker statistical difference in δ(15) N between males and females (p = 0.019, F = 5.581). One possible cause of this is a difference in the diet of males and females early in life, or alternatively, a greater susceptibility of males to nutritional deprivation compared to females. The latter argument is strengthened by a significant difference in the incidence of enamel hypoplasia between the males and females, with 7.7% of male teeth showing defects, compared to 3.9% of females. PMID:24898314

  12. Establishing spatial trends in water chemistry and stable isotopes (δ15N and δ13C) in the Elwha River prior to dam removal and salmon recolonization

    USGS Publications Warehouse

    Duda, J.J.; Coe, H.J.; Morley, S.A.; Kloehn, K.K.

    2011-01-01

    Two high-head dams on the Elwha River in Washington State (USA) have changed the migratory patterns of resident and anadromous fish, limiting Pacific salmon to the lower 7.9 km of a river that historically supported large Pacific salmon runs. To document the effects of the dams prior to their removal, we measured carbon and nitrogen stable isotope ratios of primary producers, benthic macroinvertebrates, and fish, and water chemistry above, between and below the dams. We found that δ15N was significantly higher in fish, stoneflies, black flies, periphyton and macroalgae where salmon still have access. Fish and chloroperlid stoneflies were enriched in δ13C, but the values were more variable than in δ15N. For some taxa, there were also differences between the two river sections that lack salmon, suggesting that factors other than marine-derived nutrients are structuring longitudinal isotopic profiles. Consistent with trophic theory, macroalgae had the lowest δ15N, followed by periphyton, macroinvertebrates and fish, with a range of 6.9, 6.2 and 7.7‰ below, between, and above the dams, respectively. Water chemistry analyses confirmed earlier reports that the river is oligotrophic. Phosphorous levels in the Elwha were lower than those found in other regional rivers, with significant differences among regulated, unregulated and reference sections. The removal of these dams, among the largest of such projects ever attempted, is expected to facilitate the return of salmon and their marine-derived nutrients (MDN) throughout the watershed, possibly altering the food web structure, nutrient levels and stable isotope values that we documented.

  13. Assessing waterbird habitat use in coastal evaporative systems using stable isotopes13C, δ 15N and δD) as environmental tracers

    NASA Astrophysics Data System (ADS)

    Ramírez, Francisco; Abdennadher, Aida; Sanpera, Carola; Jover, Lluís; Wassenaar, Leonard I.; Hobson, Keith A.

    2011-04-01

    Isotopic patterns of biota across salinity gradients in man-made evaporative systems could assist in determining the use of these habitats by animals. Here we report δ 13C, δ 15N and δD measurements of a euryhaline fish, the Mediterranean toothcarp ( Aphanius fasciatus), inhabiting a range of salinities in the Thyna saltworks near Sfax (Tunisia). The contribution of these salinity niches to egg formation of two typically piscivorous bird species breeding in the area and feeding within saltworks, Little Tern ( Sternula albifrons) and Little Egret ( Egretta garzetta), was inferred trough a triple-isotope13C, δ 15N and δD) Bayesian mixing model. Isotopic trends for fish δ 15N and δD across the salinity gradient followed the equations: δ 15N = e (1.1 + 47.68/Salinity) and δD = -175.74 + Salinity + Salinity 2; whereas fish δ 13C increased as salinity rose (δ 13C = -10.83 + 0.02·Salinity), after a sudden drop in fish isotopic values for salinities >60 (Practical Salinity Scale) (average fish δ 13C for salinities <60 = -5.92‰). Both bird species fed largely on low hypersalinity ponds (salinity = 43; average contribution = 37% and 22% for Little Egrets and Little Terns, respectively), although the use of intermediate hypersalinities (salinities 63 and 70) by Little Terns also occurred (16% and 21%, respectively). Isotopic patterns across salinity gradients allow the use of isotopic measurements to inform studies of habitat occupancy within evaporative systems and provide further insights into how wildlife communities interact with them.

  14. A conifer-friendly high-throughput α-cellulose extraction method for δ13C and δ18O stable isotope ratio analysis

    NASA Astrophysics Data System (ADS)

    Lin, W.; Noormets, A.; domec, J.; King, J. S.; Sun, G.; McNulty, S.

    2012-12-01

    Wood stable isotope ratios (δ13C and δ18O) offer insight to water source and plant water use efficiency (WUE), which in turn provide a glimpse to potential plant responses to changing climate, particularly rainfall patterns. The synthetic pathways of cell wall deposition in wood rings differ in their discrimination ratios between the light and heavy isotopes, and α-cellulose is broadly seen as the best indicator of plant water status due to its local and temporal fixation and to its high abundance within the wood. To use the effects of recent severe droughts on the WUE of loblolly pine (Pinus taeda) throughout Southeastern USA as a harbinger of future changes, an effort has been undertaken to sample the entire range of the species and to sample the isotopic composition in a consistent manner. To be able to accommodate the large number of samples required by this analysis, we have developed a new high-throughput method for α-cellulose extraction, which is the rate-limiting step in such an endeavor. Although an entire family of methods has been developed and perform well, their throughput in a typical research lab setting is limited to 16-75 samples per week with intensive labor input. The resin exclusion step in conifersis is particularly time-consuming. We have combined the recent advances of α-cellulose extraction in plant ecology and wood science, including a high-throughput extraction device developed in the Potsdam Dendro Lab and a simple chemical-based resin exclusion method. By transferring the entire extraction process to a multiport-based system allows throughputs of up to several hundred samples in two weeks, while minimizing labor requirements to 2-3 days per batch of samples.

  15. A stable isotope ( δ13C, δ15N) model for the North Water food web: implications for evaluating trophodynamics and the flow of energy and contaminants

    NASA Astrophysics Data System (ADS)

    Hobson, Keith A.; Fisk, Aaron; Karnovsky, Nina; Holst, Meike; Gagnon, Jean-Marc; Fortier, Martin

    fundamentally in transferring energy and carbon flux to higher trophic-level seabirds and marine mammals. We measured PCB 153 among selected organisms to investigate the behavior of bioaccumulating contaminants within the food web. Our isotopic model confirmed the trophic magnification of PCB 153 in this high-Arctic food web due to a strong correlation between contaminant concentration and organism δ15N values, demonstrating the utility of combining isotopic and contaminant approaches to food-web studies. Stable-carbon isotope analysis confirmed an enrichment in 13C between POM and ice algae (-22.3 vs. -17.7‰). Benthic organisms were generally enriched in 13C compared to pelagic species. We discuss individual species isotopic data and the general utility of our stable isotope model for defining carbon flux and contaminant flow through the North Water food web.

  16. Linkages Between Upwelling and Shell Characteristics of Mytilus californianus: Morphology and Stable Isotope13C, δ18O) Signatures of a Carbonate Archive from the California Current

    NASA Astrophysics Data System (ADS)

    Hosfelt, J. D.; Hill, T. M.; Russell, A. D.; Bean, J. R.; Sanford, E.; Gaylord, B.

    2014-12-01

    Many calcareous organisms are known to record the ambient environmental conditions in which they grow, and their calcium carbonate skeletons are often valuable archives of climate records. Mytilus californianus, a widely distributed species of intertidal mussel, experiences a spatial mosaic of oceanographic conditions as it grows within the California Current System. Periodic episodes of upwelling bring high-CO2 waters to the surface, during which California coastal waters are similar to projected conditions and act as a natural analogue to future ocean acidification. To examine the link between upwelling and shell characteristics of M. californianus, we analyzed the morphology and stable isotope13C, δ18O) signatures of mussel specimens collected live from seven study sites within the California Current System. Morphometric analyses utilized a combination of elliptic Fourier analysis and shell thickness measurements to determine the influence of low pH waters on the growth morphology and ecological fitness of M. californianus. These geochemical and morphological analyses were compared with concurrent high-resolution environmental (T, S, pH, TA, DIC) records from these seven study sites from 2010-2013. With appropriate calibration, new archives from modern M. californianus shells could provide a valuable tool to enable environmental reconstructions within the California Current System. These archives could in turn be used to predict the future consequences of continuing ocean acidification, as well as reconstruct past (archeological) conditions.

  17. Stable isotope ((13)C/(12)C and (15)N/(14)N) composition of the woolly rhinoceros Coelodonta antiquitatis horn suggests seasonal changes in the diet.

    PubMed

    Tiunov, Alexei V; Kirillova, Irina V

    2010-11-15

    The extinct woolly rhinoceros Coelodonta antiquitatis is a prominent member of the Mammuthus-Coelodonta faunal complex, but its biology is poorly known, partly because very few specimens with well-preserved soft tissues have been discovered to date. However, the permafrost-preserved horns of the woolly rhinoceros are recording structures which contain isotopic records of the diet, environmental conditions and physiological status of the animal during most of its life. In this study we report the first data on the pattern of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) isotopic composition along the nasal horn of woolly rhinoceros. We found systematic variations in δ(13)C and δ(15)N values associated with morphologically expressed transverse banding of the horn. The comparative analysis of isotopic variation in keratinous tissues of extant and extinct herbivores suggests that the oscillation in isotopic composition of the horn was induced by seasonal changes in the diet. Although the compiled evidence is in part contradictory, we suggest that more positive δ(13)C and δ(15)N values associated with dark-colored and less dense zones of the horn indicate a summer diet. More dense and light-colored zones of the horn have lower δ(13)C and δ(15)N values possibly indicating a larger proportion of woody and shrub vegetation in the winter diet. The validity of these conclusions has to be proven in further investigations, but our data underline the potential of isotopic analysis for studies on diet and habitat use by extinct members of Pleistocene fauna. PMID:20941761

  18. Similarities and differences in 13C and 15N stable isotope ratios in two non-lethal tissue types from shovelnose sturgeon Scaphirhynchus platorynchus (Rafinesque, 1820)

    USGS Publications Warehouse

    DeVries, R. J.; Schramm, Harold L., Jr.

    2015-01-01

    We tested the hypothesis that δ13C and δ15N signatures of pectoral spines would provide measures of δ13C and δ15N similar to those obtained from fin clips for adult shovelnose sturgeon Scaphirhynchus platorynchus. Thirty-two shovelnose sturgeon (fork length [FL] = 500–724 mm) were sampled from the lower Mississippi River, USA on 23 February 2013. Isotopic relationships between the two tissue types were analyzed using mixed model analysis of covariance. Tissue types differed significantly for both δ13C (P < 0.01; spine: mean = −23.83, SD = 0.62; fin clip: mean = −25.74, SD = 0.97) and δ15N (P = 0.01; spine: mean = 17.01, SD = 0.51; fin clip: mean = 17.19, SD = 0.62). Neither FL nor the FL × tissue type interaction had significant (P > 0.05) effects on δ13C. Fin clip δ13C values were highly variable and weakly correlated (r = 0.16, P = 0.40) with those from pectoral spines. We found a significant FL-tissue type interaction for δ15N, reflecting increasing δ15N with FL for spines and decreasing δ15N with FL for fin clips. These results indicate that spines are not a substitute for fin clip tissue for measuring δ13C and δ15N for shovelnose sturgeon in the lower Mississippi River, but the two tissues have different turnover rates they may provide complementary information for assessing trophic position at different time scales.

  19. Carbon-proton scalar couplings in RNA. 3D heteronuclear and 2D isotope-edited NMR of a [sup 13]C-labeled extra-stable hairpin

    SciTech Connect

    Hines, J.V.; Landry, S.M.; Varani, G.; Tinoco, I. Jr. Lawrence Berkeley Lab., CA )

    1994-06-29

    Long range carbon-proton scalar couplings were measured for an RNA hairpin of 12 nucleotides using 3D and [sup 13]C-edited 2D NMR. The large one-bond carbon-proton scalar couplings ([sup 1]J[sub CH]) and small n-bond couplings ([sup 1]J[sub CH]) produce ECOSY type cross-peaks, thus facilitating the determination of the sign and magnitude of the smaller [sup 2]J[sub CH] or [sup 3]J[sub CH]. The UUCGRNA hairpin (5[prime]-rGGACUUCGGUCC-3[prime]), whose structure has been determined by our laboratory, was uniformly [sup 13]C-labeled at 30% isotopic enrichment. The observed [sup 1]J[sub CH] couplings were then correlated to the known structure. The signs of [sup 2]J[sub C4[prime]H5[prime

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

    PubMed

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

    2007-01-16

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

  1. The signatures of stable isotopes δ 15N and δ 13C in anadromous and non-anadromous Coilia nasus living in the Yangtze River, and the adjacent sea waters

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Tang, Wenqiao; Dong, Wenxia

    2015-12-01

    Stable isotopes are increasingly used to investigate seasonal migrations of aquatic organisms. This study employed stable isotopes ( δ 13C and δ 15N) for Coilia nasus from the lower Yangtze River and the adjacent East China Sea to distinguish different ecotypic groups, ascertain trophic nutrition positions, and reflect environmental influences on C. nasus. δ 13C signatures of C. nasus sampled from Zhoushan (ZS), Chongming (CM), and Jingjiang (JJ) waters were significantly higher than those from the Poyang Lake (PYL) ( P < 0.05). By contrast, δ 15N signatures of C. nasus in ZS, CM, and JJ groups were significantly lower than those in PYL group ( P < 0.05). Basing on δ 13C and δ 15N signatures, we could distinguish anadromous (ZS, CM, and JJ) and non-anadromous (PYL) groups. The trophic level (TL) of anadromous C. nasus ranged from 2.90 to 3.04, whereas that of non-anadromous C. nasus was 4.38. C. nasus occupied the middle and top nutrition positions in the marine and Poyang Lake food webs, respectively. C. nasus in Poyang Lake were significantly more enriched in δ 15N but depleted in δ 13C, suggesting that anthropogenic nutrient inputs and terrigenous organic carbon are important to the Poyang Lake food web. This study is the first to apply δ 15N and δ 13C to population assignment studies of C. nasus in the Yangtze River and its affiliated waters. Analysis of stable isotopes ( δ 15N and δ 13C) is shown to be a useful tool for discriminating anadromous and non-anadromous C. nasus.

  2. Resiliency of Stable Isotope Fractionation (δ(13)C and δ(37)Cl) of Trichloroethene to Bacterial Growth Physiology and Expression of Key Enzymes.

    PubMed

    Buchner, Daniel; Behrens, Sebastian; Laskov, Christine; Haderlein, Stefan B

    2015-11-17

    Quantification of in situ (bio)degradation using compound-specific isotope analysis requires a known and constant isotope enrichment factor (ε). Because reported isotope enrichment factors for microbial dehalogenation of chlorinated ethenes vary considerably we studied the potential effects of metabolic adaptation to TCE respiration on isotope fractionation (δ(13)C and δ(37)Cl) using a model organism (Desulfitobacterium hafniesne Y51), which only has one reductive dehalogenase (PceA). Cells grown on TCE for the first time showed exponential growth until 10(9) cells/mL. During exponential growth, the cell-normalized amount of PceA enzyme increased steadily in the presence of TCE (up to 21 pceA transcripts per cell) but not with alternative substrates (<1 pceA transcript per cell). Cultures initially transferred or subcultivated on TCE showed very similar isotope fractionation, both for carbon (εcarbon: -8.6‰ ± 0.3‰ or -8.8‰ ± 0.2‰) and chlorine (εchlorine: -2.7‰ ± 0.3‰) with little variation (0.7‰) for the different experimental conditions. Thus, TCE isotope fractionation by D. hafniense strain Y51 was affected by neither growth phase, pceA transcription, or translation, nor by PceA content per cell, suggesting that transport limitations did not affect isotope fractionation. Previously reported variable ε values for other organohalide-respiring bacteria might thus be attributed to different expression levels of their multiple reductive dehalogenases. PMID:26505909

  3. Analyzing sites of OH radical attack (ring vs. side chain) in oxidation of substituted benzenes via dual stable isotope analysis (δ(13)C and δ(2)H).

    PubMed

    Zhang, Ning; Geronimo, Inacrist; Paneth, Piotr; Schindelka, Janine; Schaefer, Thomas; Herrmann, Hartmut; Vogt, Carsten; Richnow, Hans H

    2016-01-15

    OH radicals generated by the photolysis of H2O2 can degrade aromatic contaminants by either attacking the aromatic ring to form phenolic products or oxidizing the substituent. We characterized these competing pathways by analyzing the carbon and hydrogen isotope fractionation (εC and εH) of various substituted benzenes. For benzene and halobenzenes that only undergo ring addition, low values of εC (-0.7‰ to -1.0‰) were observed compared with theoretical values (-7.2‰ to -8‰), possibly owing to masking effect caused by pre-equilibrium between the substrate and OH radical preceding the rate-limiting step. In contrast, the addition of OH radicals to nitrobenzene ring showed a higher εC (-3.9‰), probably due to the lower reactivity. Xylene isomers, anisole, aniline, N,N-dimethylaniline, and benzonitrile yielded normal εH values (-2.8‰ to -29‰) indicating the occurrence of side-chain reactions, in contrast to the inverse εH (11.7‰ to 30‰) observed for ring addition due to an sp(2) to sp(3) hybridization change at the reacting carbon. Inverse εH values for toluene (14‰) and ethylbenzene (30‰) were observed despite the formation of side-chain oxidation products, suggesting that ring addition has a larger contribution to isotope fractionation. Dual element isotope slopes (∆δ(2)H/∆δ(13)C) therefore allow identification of significant degradation pathways of aromatic compounds by photochemically induced OH radicals. Issues that should be addressed in future studies include quantitative determination of the contribution of each competing pathway to the observed isotope fractionation and characterization of physical processes preceding the reaction that could affect isotope fractionation. PMID:26520272

  4. Stable isotopes (δ 18O and δ 13C), trace and minor element compositions of Recent scleractinians and Last Glacial bivalves at the Santa Maria di Leuca deep-water coral province, Ionian Sea

    NASA Astrophysics Data System (ADS)

    Correa, Matthias López; Montagna, Paolo; Vendrell-Simón, Begoña; McCulloch, Malcolm; Taviani, Marco

    2010-03-01

    The aragonitic skeletons of bathyal cold-water corals have a high potential as geochemical in situ archives for paleoceanography. Oxygen isotopes and stable carbon isotopes (δ 18O and δ 13C) have been analyzed, as well as trace and minor element compositions (e.g. Mg/Ca, Sr/Ca, U/Ca, B/Ca and P/Ca) in Lophelia pertusa, one of the most important frame-builders at the Santa Maria di Leuca (SML) deep-water coral hotspot in the Central Mediterranean. The Apulian Bank is swept by strong currents of the Adriatic Deep Water Outflow. The temperature of 13.9 °C is the highest temperature recorded for L. pertusa and provides an important end-member of environmental conditions for geochemical analyses on living Atlantic and Mediterranean cold-water corals. Temperature and salinity (38.77 PSU) are stable throughout the year, and thus virtually no changes should be observed in the stable oxygen isotope signal—if the coral precipitates its skeleton in equilibrium with seawater. We measured various marine properties, such as the seawater oxygen isotope composition (δ 18O sw), stable carbon isotope composition (δ 13C DIC) of dissolved inorganic carbon (DIC), and dissolved inorganic nutrient concentrations (PO 4, NO 3, NO 2, NH 3 and SiO 2). Bottom water at the coral sites shows a mean oxygen isotope composition of 1.47‰ δ 18O sw-VSMOW, and δ 13C DIC showed a mean of 1.1‰ VPDB. A section of a living L. pertusa with a thick theca calcification was probed with a Merchantek MicroMill at a high spatial sampling resolution with 10 samples per 1 mm. This reduced the signal-smoothing inherent to conventional sampling. The δ 18O ag of coral aragonite ranges between -2.0‰ and +2.8‰ VPDB and the δ 13C ag ranges between -7.77‰ and +1.47‰ VPDB. The Gaussian data distribution for both parameters, including heavy equilibrium values, suggests the completeness of the captured isotopic variability. The strict linear correlation of δ 13C and δ 18O displays a strong 'kinetic

  5. Observations of atmospheric methane and its stable isotope ratio (δ13C) over the Arctic seas from ship cruises in the summer and autumn of 2015

    NASA Astrophysics Data System (ADS)

    Skorokhod, Andrey; Belikov, Igor; Pankratova, Natalia; Novigatsky, Alexander; Thompson, Rona

    2016-04-01

    Atmospheric methane (CH4) is the second most important long-lived greenhouse gas. The Arctic has significant sources of CH4, such as from wetlands and possibly also from methane hydrates, which may act as a positive feedback on the climate system. Despite significant efforts in establishing a network of ground-based CH4 observations in the Arctic zone, there is still a lack of measurements over the Arctic Ocean and sub-polar seas. From 21 July to 9 October 2015, concentrations of CH4 and CO2, as well as of the 13C:12C isotopic ratio in CH4, i.e., δ13C, were measured in the marine boundary layer from aboard the Research Vessel "Akademik Mstislav Keldysh" by the Shirshov Institute of Oceanology. Measurements were made using a Cavity Ring Down Spectroscopy instrument from Picarro™ (model G2132-i). The cruises covered a vast area including the North Atlantic up to 70°N, the Baltic, North, Norwegian, Greenland, Barents, White, Kara and Laptev Seas. To the best of our knowledge, these are the first measurements of their type made in these regions. Concentrations of CH4 typically had low variations (in the range of a few ppb) in the open sea but relatively large variations (of the order of 100 ppb) were recorded near and during stops in ports. High variability of atmospheric CH4 was also registered near the delta of the Lena River in the Laptev Sea, which has been suggested to be a large CH4 reservoir and where bubbles rising through the water column have been observed. The obtained set of δ13CCH4 is characterized by significant range of the measured values varying from open Atlantic to polluted regions near large sea ports. The Keeling plot analyses were implemented to study possible CH4 sources according to its isotopic signature. Footprint analyses are presented for the shipboard observations, as well as comparisons to simulated CH4 concentrations and δ13C using the Lagrangian transport model, FLEXPART. This work has been carried-out with the financial support of

  6. Combination of the (87)Sr/(86)Sr ratio and light stable isotopic values (δ(13)C, δ(15)N and δD) for identifying the geographical origin of winter wheat in China.

    PubMed

    Liu, Hongyan; Wei, Yimin; Lu, Hai; Wei, Shuai; Jiang, Tao; Zhang, Yingquan; Guo, Boli

    2016-12-01

    This study aims to investigate whether isotopic signatures can be used to develop reliable fingerprints for discriminating the geographical origin of Chinese winter wheat, and to evaluate the discrimination effects of δ(13)C, δ(15)N and δD, alone or with (87)Sr/(86)Sr. In this study, the values of δ(13)C, δ(15)N and δD, and the (87)Sr/(86)Sr ratios of wheat and provenance soils from three regions were determined. Significant differences were found in all parameters of wheat and (87)Sr/(86)Sr in soil extract (reflecting the bioavailable fraction of soil) among different regions. A significantly positive correlation was observed between the (87)Sr/(86)Sr ratios of wheat and soil extracts. An overall correct classification rate of 77.8% was obtained for discriminating wheat from three regions based on light stable isotopes (δ(13)C, δ(15)N, and δD). The correct classification rate of 98.1% could be obtained with the combination of the (87)Sr/(86)Sr ratio and the light stable isotopic values. PMID:27374544

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

    NASA Astrophysics Data System (ADS)

    Fernandez, I.; Cabaneiro, A.

    2014-02-01

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

  8. Combining stable isotope13C) of trace gases and aerobiological data to monitor the entry and dispersion of microorganisms in caves.

    PubMed

    Garcia-Anton, E; Cuezva, S; Jurado, V; Porca, E; Miller, A Z; Fernandez-Cortes, A; Saiz-Jimenez, C; Sanchez-Moral, S

    2014-01-01

    Altamira Cave (north of Spain) contains one of the world's most prominent Paleolithic rock art paintings, which are threatened by a massive microbial colonization of ceiling and walls. Previous studies revealed that exchange rates between the cave and the external atmosphere through the entrance door play a decisive role in the entry and transport of microorganisms (bacteria and fungi) and nutrients to the interior of the cave. A spatial-distributed sampling and measurement of carrier (CO2) and trace (CH4) gases and isotopic signal of CO2 (δ(13)C) inside the cave supports the existence of a second connection (active gas exchange processes) with the external atmosphere at or near the Well Hall, the innermost and deepest area of the cave. A parallel aerobiological study also showed that, in addition to the entrance door, there is another connection with the external atmosphere, which favors the transport and increases microorganism concentrations in the Well Hall. This double approach provides a more complete knowledge on cave ventilation and revealed the existence of unknown passageways in the cave, a fact that should be taken into account in future cave management. PMID:23807558

  9. Changing gull diet in a changing world: a 150-year stable isotope13C, δ15N) record from feathers collected in the Pacific Northwest of North America.

    PubMed

    Blight, Louise K; Hobson, Keith A; Kyser, T Kurt; Arcese, Peter

    2015-04-01

    The world's oceans have undergone significant ecological changes following European colonial expansion and associated industrialization. Seabirds are useful indicators of marine food web structure and can be used to track multidecadal environmental change, potentially reflecting long-term human impacts. We used stable isotope (δ(13)C, δ(15)N) analysis of feathers from glaucous-winged gulls (Larus glaucescens) in a heavily disturbed region of the northeast Pacific to ask whether diets of this generalist forager changed in response to shifts in food availability over 150 years, and whether any detected change might explain long-term trends in gull abundance. Sampled feathers came from birds collected between 1860 and 2009 at nesting colonies in the Salish Sea, a transboundary marine system adjacent to Washington, USA and British Columbia, Canada. To determine whether temporal trends in stable isotope ratios might simply reflect changes to baseline environmental values, we also analysed muscle tissue from forage fishes collected in the same region over a multidecadal timeframe. Values of δ(13)C and δ(15)N declined since 1860 in both subadult and adult gulls (δ(13)C, ~ 2-6‰; δ(15)N, ~4-5‰), indicating that their diet has become less marine over time, and that birds now feed at a lower trophic level than previously. Conversely, forage fish δ(13)C and δ(15)N values showed no trends, supporting our conclusion that gull feather values were indicative of declines in marine food availability rather than of baseline environmental change. Gradual declines in feather isotope values are consistent with trends predicted had gulls consumed less fish over time, but were equivocal with respect to whether gulls had switched to a more garbage-based diet, or one comprising marine invertebrates. Nevertheless, our results suggest a long-term decrease in diet quality linked to declining fish abundance or other anthropogenic influences, and may help to explain regional

  10. 13C FRACTIONATION DURING RELIC SOIL ORGANIC C MINERALIZATION ON CARBON BUDGETS AND HALF-LIVES CALCULATED USING THE STABLE ISOTOPE APPROACH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The 13C natural abundance approach for determining soil organic C (SOC) stability and turnover has been used to determine SOC mineralization kinetics. These calculations often assume that 13C fractionation during relic SOC and non-harvested biomass mineralization is insignificant. The objective of t...

  11. Stable carbon ((12/13)C) and nitrogen ((14/15)N) isotopes as a tool for identifying the sources of cyanide in wastes and contaminated soils--a method development.

    PubMed

    Weihmann, Jenny; Mansfeldt, Tim; Schulte, Ulrike

    2007-01-23

    The occurrence of iron-cyanide complexes in the environment is of concern, since they are potentially hazardous. In order to determine the source of iron-cyanide complexes in contaminated soils and wastes, we developed a method based on the stable isotope ratios (13)C/(12)C and (15)N/(14)N of the complexed cyanide-ion (CN(-)). The method was tested on three pure chemicals and two industrials wastes: blast-furnace sludge (BFS) and gas-purifier waste (GPW). The iron-cyanide complexes were converted into the solid cupric ferrocyanide, Cu(2)[Fe(CN)(6)].7H(2)O, followed by combustion and determination of the isotope-ratios by continuous flow isotope ratio mass spectrometry. Cupric ferrocyanide was obtained from the materials by (i) an alkaline extraction with 1M NaOH and (ii) a distillate digestion. The [Fe(CN)(6)](4-) of the alkaline extraction was precipitated after adding Cu(2+). The CN(-) of the distillate digestion was at first complexed with Fe(2+) under inert conditions and then precipitated after adding Cu(2+). The delta(13)C-values obtained by the two methods differed slightly up to 1-3 per thousand for standards and BFS. The difference was larger for alkaline-extracted GPW (4-7 per thousand), since non-cyanide C was co-extracted and co-precipitated. Therefore the distillate digestion technique is recommended when determining the C isotope ratios in samples rich in organic carbon. Since the delta(13)C-values of BFS are in the range of -30 to -24 per thousand and of -17 to -5 per thousand for GPW, carbon seems to be a suitable tracer for identifying the source of cyanide in both wastes. However, the delta(15)N-values overlapped for BFS and GPW, making nitrogen unsuitable as a tracer. PMID:17386516

  12. Draft Genome Sequence of Uncultivated Desulfosporosinus sp. Strain Tol-M, Obtained by Stable Isotope Probing Using [13C6]Toluene

    PubMed Central

    Abu Laban, Nidal; Tan, BoonFei; Dao, Anh

    2015-01-01

    A draft Desulfosporosinus genome was assembled from the metagenome of a methanogenic [13C6]toluene-degrading community. The Desulfosporosinus sp. strain Tol-M genome is distinguished from that of previously published Desulfosporosinus strain by containing bss, bbs, and bam genes encoding enzymes for anaerobic biodegradation of monoaromatic hydrocarbons and lacking dsrAB genes for dissimilatory sulfate reduction. PMID:25593260

  13. Microbial 13C utilization patterns via stable isotope probing of phospholipid biomarkers in Mojave Desert soils exposed to ambient and elevated atmospheric CO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Changes in plant inputs under changing atmospheric CO2 can be expected to alter the size and/or composition of active soil microbial communities which determine whether soils are a C sink or source. Autotrophically-fixed 13C was traced into phospholipid fatty acid (PLFA) biomarkers in Mojave Desert...

  14. A stable isotope13C and δ15N) perspective on human diet on Rapa Nui (Easter Island) ca. AD 1400-1900.

    PubMed

    Commendador, Amy S; Dudgeon, John V; Finney, Bruce P; Fuller, Benjamin T; Esh, Kelley S

    2013-10-01

    Ecological and environmental evidence suggests that Rapa Nui was among the most marginally habitable islands in Eastern Polynesia, with only a fraction of the biotic diversity found on archipelagos to the west, and capable of sustaining many fewer cultigens traditionally transported by Polynesian colonizers. However, archaeological evidence for human dietary adaptations under such restrictions is limited. Little is known about the particulars of the subsistence base and dietary changes on Rapa Nui that may be associated with a hypothesized late prehistoric decline in the quality and diversity of food sources. To better understand prehistoric Rapa Nui diet we examined stable carbon and nitrogen isotope compositions of human teeth along with archaeological faunal material thought to comprise the Rapa Nui food web. Our results indicate that contrary to previous zooarchaeological studies diet was predominantly terrestrial throughout the entire sequence of occupation, with reliance on rats, chickens and C3 plants. While a few individuals may have had access to higher trophic level marine resources, this is evident only later in time (generally post-AD 1600). A decline in (15)N through time was observed, and may be attributed to declines in available terrestrial proteins; however, presently we cannot rule out the effect of changing soil and plant baseline δ(15)N. Our results also suggest differential access to higher trophic level marine resources among contemporaneous populations, but more research is required to clarify this observation. PMID:23996514

  15. Latest Paleocene benthic extinction event on the southern Tethyan shelf (Egypt): Foraminiferal stable isotopic13C, δ18O) records

    NASA Astrophysics Data System (ADS)

    Schmitz, B.; Speijer, R. P.; Aubry, M.-P.

    1996-04-01

    The dramatic global extinction of 35% 50% of benthic foraminifera species in the deep sea in the latest Paleocene and associated negative excursions in δ13C and δ18O may be related to spreading of warm, saline bottom water from subtropical Tethyan shallow regions over the sea floor worldwide. Our study of neritic sections in Egypt shows that in the southern shallow Tethys, a prominent long-term change in bottom-water chemistry, sedimentation, and benthic foraminifera fauna was initiated at the time when the deep-sea benthic extinction event (BEE) took place. Bottom-water δ13C values on the Tethyan shelf show a sudden 3.0‰ negative shift at this event; however, contrary to the deep sea, in which the δ13C excursion was of short duration, Tethyan δ13C values did not fully return to preboundary values, but remained depressed by ˜1.5‰ for at least 1 m.y. The δ13C values at the Egyptian shelf during the BEE are much lower than would be expected if this was a source region for global deep water. The δ18O values indicate no significant change in bottom-water salinity or temperature at the BEE. The long-lasting environmental changes that began on the Egyptian shelf at the BEE may be related to, for example, gateway reorganization along the Tethyan seaway. Paleogeographic changes possibly also triggered a change in the loci of global deep-water formation; however, these loci must be sought in another part of the Tethys.

  16. Life history of the individuals buried in the St. Benedict Cemetery (Prague, 15th-18th centuries): insights from (14)C dating and stable isotope (δ(13)C, δ(15)N, δ(18)O) analysis.

    PubMed

    Salesse, Kevin; Dufour, Élise; Castex, Dominique; Velemínský, Petr; Santos, Frédéric; Kuchařová, Hedvika; Jun, Libor; Brůžek, Jaroslav

    2013-06-01

    Funerary practices and bioarchaeological (sex and age) data suggest that a mortality crisis linked to an epidemic episode occurred during the fifth phase of the St. Benedict cemetery in Prague (Czech Republic). To identify this mass mortality episode, we reconstructed individual life histories (dietary and mobility factors), assessed the population's biological homogeneity, and proposed a new chronology through stable isotope analysis (δ(13)C, δ(18)O and δ(15)N) and direct radiocarbon dating. Stable isotope analysis was conducted on the bone and tooth enamel (collagen and carbonate) of 19 individuals from three multiple graves (MG) and 12 individuals from individual graves (IG). The δ(15)N values of collagen and the difference between the δ(13)C values of collagen and bone carbonate could indicate that the IG individuals had a richer protein diet than the MG individuals or different food resources. The human bone and enamel carbonate and δ(18)O values suggest that the majority of individuals from MG and all individuals from IG spent most of their lives outside of the Bohemian region. Variations in δ(18)O values also indicate that all individuals experienced residential mobility during their lives. The stable isotope results, biological (age and sex) data and eight (14)C dates clearly differentiate the MG and IG groups. The present work provides evidence for the reuse of the St. Benedict cemetery to bury soldiers despite the funeral protest ban (1635 AD). The Siege of Prague (1742 AD) by French-Bavarian-Saxon armies is identified as the cause of the St. Benedict mass mortality event. PMID:23588853

  17. Study of Urban environmental quality through Isotopes δ13C

    NASA Astrophysics Data System (ADS)

    González-Sosa, E.; Mastachi-Loza, C.; Becerril-Piña, R.; Ramos-Salinas, N. M.

    2012-04-01

    Usually, trees with similar pH values on their bark develop epiphytes of similar species, the acidity to be a factor for growth. The aim of the study was evaluate the air quality through isotope δ13C in order to define the levels of environmental quality in the city of Queretaro, Mexico. In this work were collected at least 4 epiphytes positioned in trees of the species Prosopis Laevigata at 25 sites of Queretaro City. The samples were analyzed for trace elements with an inductively coupled plasma atomic emission spectroscopy (ICP). The collecting took place during dry period, in May and early rain June 2011 period, and on four sectors to identify the spatial distribution of pollution, using isotopic analysis of concentration of δ 13C. According with the results there are significant differences among the species in each of the sampled areas. The 5 February Avenue presented greater diversity and richness of δ13C, followed by those who were surveyed in the proximity of the UAQ and finally in the middle-east area. An average value of δ13C-17.92%, followed by those surveyed in the vicinity of the UAQ that correspond to sector I and II with an concentration of δ13C-17.55% and δ13C-17.22%, and finally the samples collected in trees scattered in the East-Sector II and IV with a value of δ13C-17.02% and δ13C-15.62%, respectively. Also were observed differences between the dry and wet period. It is likely that these results of δ 13C in moist period reflect the drag of the isotopes due to rain events that could mark a trend in the dilution of this element, however there is a trend in terms of abundance and composition of finding more impact in those species sampled in dry period, in May and early June 2011.

  18. Simultaneous determination of stable isotopic compositions of nitrous oxide (δ15N and δ18O of N2O) and methane (δ13C of CH4) in nanomolar quantities from a single water sample

    NASA Astrophysics Data System (ADS)

    Hirota, A.; Tsunogai, U.; Komatsu, D. D.; Nakagawa, F.

    2010-12-01

    The stable isotopic compositions of nitrous oxide (δ15N of N2O and δ18O of N2O, respectively) and methane (δ13C of CH4) have provided us with some interesting geochemical insights. We have developed a rapid, sensitive, and automated analytical system to simultaneously determine the concentrations and stable isotopic compositions of nanomolar quantities of N2O and CH4 in the environmental water, by combining continuous-flow isotope-ratio mass spectrometry and a He-sparging system to extract and purify the dissolved gases. Our system, which is composed of a sparging bottle, a chemical trap, four cold traps and a capillary gas chromatograph that use ultra-pure helium as the carrier gas, achieves complete extraction of N2O and CH4 in a water sample and separation among N2O, CH4, and the other component gases. The flow path subsequent to gas chromatograph was periodically changed to pass the gases through the combustion furnace to convert CH4 and the other hydrocarbons into CO2, or to bypass the combustion furnace for the direct introduction of eluted N2O into the mass spectrometer, for determining the stable isotopic compositions through monitoring m/z = 44, 45, and 46, on the bases of CO2+ and N2O+, respectively. The analytical system can be operated automatically with sequential software programmed on a personal computer. The analytical precisions (the standard deviation of a single measurement) were better than 0.2‰ for δ15N of N2O and 0.3‰ for δ18O of N2O, in the case of more than 6.7 nmol N2O injection and better than 1.4‰ for δ15N of N2O and 2.6‰ for δ18O of N2O, in the case of more than 0.2 nmol N2O injection, respectively. Simultaneously, the analytical precisions were better than 0.07‰ for δ13C of CH4, in the case of more than 5.5 nmol CH4 infection and better than 2.1‰ for δ13C of CH4, when more than 0.024 nmol CH4 injection. In this manner, we can simultaneously determine stable isotopic compositions of a 120 mL water sample having

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

    USGS Publications Warehouse

    Révész, Kinga M.; Doctor, Daniel H.

    2014-01-01

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

  20. Conifers, Angiosperm Trees, and Lianas: Growth, Whole-Plant Water and Nitrogen Use Efficiency, and Stable Isotope Composition (δ13C and δ18O) of Seedlings Grown in a Tropical Environment1[W][OA

    PubMed Central

    Cernusak, Lucas A.; Winter, Klaus; Aranda, Jorge; Turner, Benjamin L.

    2008-01-01

    Seedlings of several species of gymnosperm trees, angiosperm trees, and angiosperm lianas were grown under tropical field conditions in the Republic of Panama; physiological processes controlling plant C and water fluxes were assessed across this functionally diverse range of species. Relative growth rate, r, was primarily controlled by the ratio of leaf area to plant mass, of which specific leaf area was a key component. Instantaneous photosynthesis, when expressed on a leaf-mass basis, explained 69% of variation in r (P < 0.0001, n = 94). Mean r of angiosperms was significantly higher than that of the gymnosperms; within angiosperms, mean r of lianas was higher than that of trees. Whole-plant nitrogen use efficiency was also significantly higher in angiosperm than in gymnosperm species, and was primarily controlled by the rate of photosynthesis for a given amount of leaf nitrogen. Whole-plant water use efficiency, TEc, varied significantly among species, and was primarily controlled by ci/ca, the ratio of intercellular to ambient CO2 partial pressures during photosynthesis. Instantaneous measurements of ci/ca explained 51% of variation in TEc (P < 0.0001, n = 94). Whole-plant 13C discrimination also varied significantly as a function of ci/ca (R2 = 0.57, P < 0.0001, n = 94), and was, accordingly, a good predictor of TEc. The 18O enrichment of stem dry matter was primarily controlled by the predicted 18O enrichment of evaporative sites within leaves (R2 = 0.61, P < 0.0001, n = 94), with some residual variation explained by mean transpiration rate. Measurements of carbon and oxygen stable isotope ratios could provide a useful means of parameterizing physiological models of tropical forest trees. PMID:18599645

  1. Natural isotope correction of MS/MS measurements for metabolomics and (13) C fluxomics.

    PubMed

    Niedenführ, Sebastian; Ten Pierick, Angela; van Dam, Patricia T N; Suarez-Mendez, Camilo A; Nöh, Katharina; Wahl, S Aljoscha

    2016-05-01

    Fluxomics and metabolomics are crucial tools for metabolic engineering and biomedical analysis to determine the in vivo cellular state. Especially, the application of (13) C isotopes allows comprehensive insights into the functional operation of cellular metabolism. Compared to single MS, tandem mass spectrometry (MS/MS) provides more detailed and accurate measurements of the metabolite enrichment patterns (tandem mass isotopomers), increasing the accuracy of metabolite concentration measurements and metabolic flux estimation. MS-type data from isotope labeling experiments is biased by naturally occurring stable isotopes (C, H, N, O, etc.). In particular, GC-MS(/MS) requires derivatization for the usually non-volatile intracellular metabolites introducing additional natural isotopes leading to measurements that do not directly represent the carbon labeling distribution. To make full useof LC- and GC-MS/MS mass isotopomer measurements, the influence of natural isotopes has to be eliminated (corrected). Our correction approach is analyzed for the two most common applications; (13) C fluxomics and isotope dilution mass spectrometry (IDMS) based metabolomics. Natural isotopes can have an impact on the calculated flux distribution which strongly depends on the substrate labeling and the actual flux distribution. Second, we show that in IDMS based metabolomics natural isotopes lead to underestimated concentrations that can and should be corrected with a nonlinear calibration. Our simulations indicate that the correction for natural abundance in isotope based fluxomics and quantitative metabolomics is essential for correct data interpretation. Biotechnol. Bioeng. 2016;113: 1137-1147. © 2015 Wiley Periodicals, Inc. PMID:26479486

  2. Design and operation of a continuous 13C and 15N labeling chamber for uniform or differential, metabolic and structural, plant tissue isotope labeling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tracing heavy stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes and soil organic matter formation to small-scale stable-isotope biomarker probing. Coupling multiple stable isotopes such as 13C with 15N, 18O o...

  3. Defining fish community structure in Lake Winnipeg using stable isotopes (δ(13)C, δ(15)N, δ(34)S): implications for monitoring ecological responses and trophodynamics of mercury & other trace elements.

    PubMed

    Ofukany, Amy F A; Wassenaar, Leonard I; Bond, Alexander L; Hobson, Keith A

    2014-11-01

    The ecological integrity of freshwater lakes is influenced by atmospheric and riverine deposition of contaminants, shoreline development, eutrophication, and the introduction of non-native species. Changes to the trophic structure of Lake Winnipeg, Canada, and consequently, the concentrations of contaminants and trace elements measured in tissues of native fishes, are likely attributed to agricultural runoff from the 977,800 km(2) watershed and the arrival of non-native zooplankters and fishes. We measured δ(13)C, δ(15)N, and δ(34)S along with concentrations of 15 trace elements in 17 native fishes from the north and south basins of Lake Winnipeg in 2009 and 2010. After adjusting for differences in isotopic baseline values between the two basins, fishes in the south basin had consistently higher δ(13)C and δ(34)S, and lower δ(15)N. We found little evidence of biomagnification of trace elements at the community level, but walleye (Sander vitreus) and freshwater drum (Aplodinotus grunniens) had higher mercury and selenium concentrations with increased trophic position, coincident with increased piscivory. There was evidence of growth dilution of cobalt, copper, manganese, molybdenum, thallium, and vanadium, and bioaccumulation of mercury, which could be explained by increases in algal (and consequently, lake and fish) productivity. We conclude that the north and south basins of Lake Winnipeg represent very different communities with different trophic structures and trace element concentrations. PMID:25129159

  4. Influence of 13C isotopic labeling location of 13C DNP of acetate using TEMPO free radical

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Lumata, Lloyd

    2015-03-01

    Dynamic nuclear polarization (DNP) via the dissolution method enhances the liquid-state magnetic resonance (NMR or MRI) signals of insensitive nuclear spins by at least 10,000-fold. The basis for all these signal enhancements at room temperature is the polarization transfer from the electrons to nuclear spins at cryogenic temperature and high magnetic field. In this work, we have studied the influence of the location of 13C isotopic labeling on the DNP of sodium acetate at 3.35 T and 1.4 K using a wide ESR linewidth free radical 4-oxo-TEMPO. The carbonyl [1-13C]acetate spins produced a polarization level that is almost twice that of the methyl [2-13C]acetate spins. On the other hand, the polarization of the methyl 13C spins doubled to reach the level of [1-13C]acetate when the methyl group was deuterated. Meanwhile, the solid-state nuclear relaxation of these samples are the same and do not correlate with the polarization levels. These behavior implies that the nuclear relaxation for these samples is dominated by the contribution from the free radicals and the polarization levels can be explained by a thermodynamic picture of DNP.

  5. Paleoclimate record from Zidita Cave (Romania) using guano-derived δ13C isotopic data

    NASA Astrophysics Data System (ADS)

    Forray, Ferenc L.; Giurgiu, Alexandra; Onac, Bogdan P.; Tămaş, Tudor

    2014-05-01

    In this study, we measured the carbon isotopic composition of a core taken from a bat guano deposit in Zidita Cave (Metaliferi Mountains, Romania). The cave develops in Late Jurassic limestones, has a total length of 547 m, and its entrance was fortified during the XIV - XVIII centuries. The cave is a fossil maze with a filling represented by limestone blocks, clay sediments, and scarce calcite speleothems. The guano accumulation, 1.5 m thick, is located in a small room towards the end of the cave, under a Rhinolophus euryale roost site.The core was recovered with a Russian peat corer. 14C dating performed on the guano indicates a continuous deposition since ca. 500 years BP, but however, the upper first meter of the core has a modern age and high radiocarbon activity acquired from atmospheric radiocarbon bomb pulse. The core was sampled at 2 cm ± 2 mm intervals for δ13C analyses (76 samples) and at 5 cm for pollen. The investigations were carried out using a Picarro G2121-i δ13C analyzer (Combustion Module coupled with a Cavity Ring Down Spectroscopy technique) at the Stable Isotope Laboratory of the Department of Geology, Babes-Bolyai University (Cluj-Napoca, Romania). The result shows that guano δ13C range from -24.07 to -27.61 o‰The carbon isotopic profile indicates two major wet periods and 2 to 3 shorter periods characterized by drier climate.

  6. The use of isotope ratios (13C/12C) for vegetable oils authentication

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    Stable isotopes are now increasingly used for the control of the geographical origin or authenticity of food products. The falsification may be more or less sophisticated and its sophistication as well as its costs increases with the improvement of analytical methods. In this study 22 vegetable oils (olive, sunflower, palm, maize) commercialized on Romanian market were investigated by mean of δ13C in bulk oil and the obtained results were compared with those reported in literature in order to check the labeling of these natural products. The obtained results were in the range of the mean values found in the literature for these types of oils, thus providing their accurate labeling.

  7. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: CO : CO2, N2O : CO2, CH4 : CO2, O2 : CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    NASA Astrophysics Data System (ADS)

    Popa, M. E.; Vollmer, M. K.; Jordan, A.; Brand, W. A.; Pathirana, S. L.; Rothe, M.; Röckmann, T.

    2014-02-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2 / N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO : CO2 ratios, with an average of (4.15 ± 0.34) ppb:ppm, are lower than reported in previous studies, pointing to a reduction in CO emissions from traffic. The 13C in CO2 reflects the isotopic composition of the fuel. 18O in CO2 is slightly depleted compared to the 18O in atmospheric O2, and shows significant variability. In contrast, the δ13C values of CO show that significant fractionation takes place during CO destruction in the catalytic converter. 13C in CO is enriched by 3‰ compared to the 13C in the fuel burnt, while the 18O content is similar to that of atmospheric O2. We compute a fractionation constant of (-2.7 ± 0.7)‰ for 13C during CO destruction. The N2O : CO2 average ratio of (1.8 ± 0.2) × 10-2 ppb:ppm is significantly lower than in past studies, showing a reduction in N2O emissions likely related to improvements in the catalytic converter technology. We also observed small CH4 emissions, with an average CH4 : CO2 ratio of (4.6 ± 0.2) × 10-2 ppb:ppm. The O2 : CO2 ratios of (-1.47 ± 0.01) ppm:ppm are very close to the expected, theoretically calculated values of O2 depletion per CO2 enhancement.

  8. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: CO : CO2, N2O : CO2, CH4 : CO2, O2 : CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    NASA Astrophysics Data System (ADS)

    Popa, M. E.; Vollmer, M. K.; Jordan, A.; Brand, W. A.; Pathirana, S. L.; Rothe, M.; Röckmann, T.

    2013-09-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the highway tunnel Islisberg (Switzerland). The CO : CO2 ratios, with an average of (4.15 ± 0.34) ppb : ppm, are lower than reported by previous studies, pointing to a reduction in CO emissions from traffic. The 13C in CO2 reflects the isotopic composition of the fuel. 18O in CO2 is slightly depleted compared to the 18O in atmospheric O2, and shows significant variability. In contrast, the δ13C values of CO show that significant fractionation takes place during CO destruction in the catalytic converter. 13C in CO is enriched by 3 ‰ compared to the 13C in the fuel burnt, while the 18O content is similar to that of atmospheric O2. We compute a fractionation constant of (-2.7 ± 0.7) ‰ for 13C during CO destruction. The N2O : CO2 average ratio (1.8 ± 0.2) × 10-2 ppb : ppm is significantly lower than in past studies, showing a reduction in N2O emissions likely related to improvements in the catalytic technology. We also observed small CH4 emissions, with an average CH4 : CO2 ratio of (4.6 ± 0.2) × 10-2 ppb : ppm. The O2 : CO2 ratios of (-1.47 ± 0.01) ppm : ppm are very close to the expected, theoretically calculated values.

  9. Performance evaluation of quantitative adiabatic (13)C NMR pulse sequences for site-specific isotopic measurements.

    PubMed

    Thibaudeau, Christophe; Remaud, Gérald; Silvestre, Virginie; Akoka, Serge

    2010-07-01

    (2)H/(1)H and (13)C/(12)C site-specific isotope ratios determined by NMR spectroscopy may be used to discriminate pharmaceutically active ingredients based on the synthetic process used in production. Extending the Site-specific Natural Isotope Fractionation NMR (SNIF-NMR) method to (13)C is highly beneficial for complex organic molecules when measurements of (2)H/(1)H ratios lead to poorly defined molecular fingerprints. The current NMR methodology to determine (13)C/(12)C site-specific isotope ratios suffers from poor sensitivity and long experimental times. In this work, several NMR pulse sequences based on polarization transfer were evaluated and optimized to measure precise quantitative (13)C NMR spectra within a short time. Adiabatic 180 degrees (1)H and (13)C pulses were incorporated into distortionless enhancement by polarization transfer (DEPT) and refocused insensitive nuclei enhanced by polarization transfer (INEPT) to minimize the influence of 180 degrees pulse imperfections and of off-resonance effects on the precision of the measured (13)C peak areas. The adiabatic DEPT sequence was applied to draw up a precise site-specific (13)C isotope profile of ibuprofen. A modified heteronuclear cross-polarization (HCP) experiment featuring (1)H and (13)C spin-locks with adiabatic 180 degrees pulses is also introduced. This sequence enables efficient magnetization transfer across a wide (13)C frequency range although not enough for an application in quantitative (13)C isotopic analysis. PMID:20527737

  10. Stable isotope studies

    SciTech Connect

    Ishida, T.

    1992-01-01

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

  11. Efficient Total Chemical Synthesis of (13) C=(18) O Isotopomers of Human Insulin for Isotope-Edited FTIR.

    PubMed

    Dhayalan, Balamurugan; Fitzpatrick, Ann; Mandal, Kalyaneswar; Whittaker, Jonathan; Weiss, Michael A; Tokmakoff, Andrei; Kent, Stephen B H

    2016-03-01

    Isotope-edited two-dimensional Fourier transform infrared spectroscopy (2 D FTIR) can potentially provide a unique probe of protein structure and dynamics. However, general methods for the site-specific incorporation of stable (13) C=(18) O labels into the polypeptide backbone of the protein molecule have not yet been established. Here we describe, as a prototype for the incorporation of specific arrays of isotope labels, the total chemical synthesis-via a key ester insulin intermediate-of 97 % enriched [(1-(13) C=(18) O)Phe(B24) ] human insulin: stable-isotope labeled at a single backbone amide carbonyl. The amino acid sequence as well as the positions of the disulfide bonds and the correctly folded structure were unambiguously confirmed by the X-ray crystal structure of the synthetic protein molecule. In vitro assays of the isotope labeled [(1-(13) C=(18) O)Phe(B24) ] human insulin showed that it had full insulin receptor binding activity. Linear and 2 D IR spectra revealed a distinct red-shifted amide I carbonyl band peak at 1595 cm(-1) resulting from the (1-(13) C=(18) O)Phe(B24) backbone label. This work illustrates the utility of chemical synthesis to enable the application of advanced physical methods for the elucidation of the molecular basis of protein function. PMID:26715336

  12. Theoretical Calibration on the 13C-18O Clumped Isotope Thermometer

    NASA Astrophysics Data System (ADS)

    Tang, M.; Zhang, S. T.; LIU, Q.; Liu, Y.

    2014-12-01

    The kinetic isotope effect (KIE) arisen from phosphoric acid digestion of carbonates has been noticed since the beginning of stable isotope geochemistry. However, the molecular level details of this reaction have not been fully understood yet. Equilibrium 13C-18O clumped isotope distribution in carbonates has been suggested as a new thermometer for surface temperature systems; nevertheless, existing Δ47-T relationships calibrated by several different groups are incompatible, generating substantial confusions and debates about those variations. Here we propose a new molecular-level mechanism with three parallel pathways for the phosphoric acid digestion of carbonates. We show that the KIE of such reaction can be different if the relative contributions of the three parallel pathways are changed. This new mechanism abandons completely a previously proposed molecular mechanism (i.e., Guo et al., 2009) and can explain (at least partly) why the Δ47-T relationships provided by different groups are different. Together with a re-calculated equilibrium clumped isotope fractionation factors of carbonate minerals using a new volume-variable-cluster-model method with higher theoretical-level treatments and higher-order anharmonic corrections, we present a theoretical (equilibrium + KIE) Δ47-T relationship for carbonates. Our theoretical calibration line is with large variations due to considering possible changes of relative contributions of the three parallel pathways and different carbonate mineral used. For minimizing the variation, we suggest using the same amount of sample, the same mineral and the same temperature of phosphoric acid digestion for this experiment.

  13. Embryotoxicity of stable isotopes and use of stable isotopes in studies of teratogenetic mechanisms

    SciTech Connect

    Spielmann, H.; Nau, H.

    1986-07-01

    Experiments on teratogenic effects of stable isotopes from our own and other laboratories are evaluated. In the first series of investigations, the enrichment of the stable isotope /sup 13/C derived from U-/sup 13/C-glucose was studied in mouse embryos at various stages of development, including limb buds in organ culture. Preimplantation mouse embryos incubated in vitro in /sup 13/C-enriched medium for 48 hours showed normal development during subsequent differentiation in vitro and also in vivo after embryo transfer to faster mothers. These embryos were 15% to 20% enriched in /sup 13/C. Administration of U-13-C-glucose to pregnant mice during organogenesis led to an increase of the absolute /sup 13/C content of the embryo for several days after the end of isotope administration, whereas the enrichment in maternal tissue decreased. No alterations of embryonic development were detected due to stable isotope enrichment. Development of cultured mouse limb buds was unaffected by incubation with 82 mol% U-/sup 13/C-glucose as judged from morphologic and biochemical criteria. The second part of the article describes the value of deuterium-labeled drugs as probes into the mechanism of activation of teratogenic metabolites. A comparison of the pharmacokinetics as well as the teratogenicity between cyclophosphamide and some specific deuterium-labeled analogues showed that the isotope effect observed can be related to a particular metabolic pathway crucial for teratogenic activation by this drug.

  14. Mapping photoautotrophic metabolism with isotopically nonstationary (13)C flux analysis.

    PubMed

    Young, Jamey D; Shastri, Avantika A; Stephanopoulos, Gregory; Morgan, John A

    2011-11-01

    Understanding in vivo regulation of photoautotrophic metabolism is important for identifying strategies to improve photosynthetic efficiency or re-route carbon fluxes to desirable end products. We have developed an approach to reconstruct comprehensive flux maps of photoautotrophic metabolism by computational analysis of dynamic isotope labeling measurements and have applied it to determine metabolic pathway fluxes in the cyanobacterium Synechocystis sp. PCC6803. Comparison to a theoretically predicted flux map revealed inefficiencies in photosynthesis due to oxidative pentose phosphate pathway and malic enzyme activity, despite negligible photorespiration. This approach has potential to fill important gaps in our understanding of how carbon and energy flows are systemically regulated in cyanobacteria, plants, and algae. PMID:21907300

  15. LASER BIOLOGY AND MEDICINE: Laser analysis of the 13C/12C isotope ratio in CO2 in exhaled air

    NASA Astrophysics Data System (ADS)

    Stepanov, E. V.

    2002-11-01

    Tunable diode lasers (TDLs) are applied to the diagnostics of gastroenterological diseases using respiratory tests and preparations enriched with the stable 13C isotope. This method of the analysis of the 13C/12C isotope ratio in CO2 in exhaled air is based on the selective measurement of the resonance absorption at the vibrational — rotational structure of 12CO2 and 13CO2. The CO2 transmission spectra in the region of 4.35 μm were measured with a PbEuSe double-heterostructure TDL. The accuracy of carbon isotope ratio measurements in CO2 of exhaled air performed with the TDL was ~0.5%. The data of clinical tests of the developed laser-based analyser are presented.

  16. Analogy between mission critical detection in distributed systems and 13C isotope separation column

    NASA Astrophysics Data System (ADS)

    Boca, Maria L.; Secara, Mihai

    2015-02-01

    Carbon represents the fourth most abundant chemical element in the world, having two stable and one radioactive isotope. The 13 Carbon isotopes, with a natural abundance of 1.1%, plays an important role in numerous applications, such as the study of human metabolism changes, molecular structure studies, non-invasive respiratory tests, Alzheimer tests, air pollution and global warming effects on plants [2]. Distributed systems are increasingly being applied in critical real-time applications and their complexity forces programmers to use design methods which guarantee correctness and increase the maintainability of the products. Objectoriented methodologies are widely used to cope with complexity in any kind of system, but most of them lack a formal foundation to allow the analysis and verification of designs, which is one of the main requirements for dealing with concurrent and reactive systems. This research is intended to make an analogy between two tips of industrial processes, one 13C Isotope Separation Column and other one distributed systems. We try to highlight detection of "mission critical "situations for this two processes and show with one is more critical and needs deeply supervisyon [1], [3].

  17. sup 13 C and sup 18 O isotopic disequilibrium in biological carbonates: I. Patterns

    SciTech Connect

    McConnaughey, T. )

    1989-01-01

    Biological carbonates frequently precipitate out of {sup 18}O and {sup 13}C equilibrium with ambient waters. Two patterns of isotopic disequilibrium are particularly common. Kinetic disequilibria, so designated because they apparently result from kinetic isotope effects during CO{sub 2} hydration and hydroxylation, involve simultaneous depletions of {sup 18}O and {sup 13}C as large as 4{per thousand} and 10 to 15{per thousand}, respectively. Rapid skeletogenesis favors strong kinetic effects, and approximately linear correlations between skeletal {delta}{sup 18}O and {delta}{sup 13}C are common in carbonates showing mainly the kinetic pattern. Metabolic effects involve additional positive or negative modulation of skeletal {delta}{sup 13}C, reflecting changes in the {delta}{sup 13}C of dissolved inorganic carbon, caused mainly by photosynthesis and respiration. Kinetic isotope disequilibria tend to be fairly consistent in rapidly growing parts of photosynthetic corals, and time dependent isotopic variations therefore reflect changes in environmental conditions. {delta}{sup 18}O variations from Galapagos corals yields meaningful clues regarding seawater temperature, while {delta}{sup 13}C variations reflect changes in photosynthesis, modulated by cloudiness.

  18. Liquid chromatography combined with mass spectrometry for 13C isotopic analysis in life science research.

    PubMed

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

    2007-01-01

    Among the different disciplines covered by mass spectrometry, measurement of (13)C/(12)C isotopic ratio crosses a large section of disciplines from a tool revealing the origin of compounds to more recent approaches such as metabolomics and proteomics. Isotope ratio mass spectrometry (IRMS) and molecular mass spectrometry (MS) are the two most mature techniques for (13)C isotopic analysis of compounds, respectively, for high and low-isotopic precision. For the sample introduction, the coupling of gas chromatography (GC) to either IRMS or MS is state of the art technique for targeted isotopic analysis of volatile analytes. However, liquid chromatography (LC) also needs to be considered as a tool for the sample introduction into IRMS or MS for (13)C isotopic analyses of non-volatile analytes at natural abundance as well as for (13)C-labeled compounds. This review presents the past and the current processes used to perform (13)C isotopic analysis in combination with LC. It gives particular attention to the combination of LC with IRMS which started in the 1990's with the moving wire transport, then subsequently moved to the chemical reaction interface (CRI) and was made commercially available in 2004 with the wet chemical oxidation interface (LC-IRMS). The LC-IRMS method development is also discussed in this review, including the possible approaches for increasing selectivity and efficiency, for example, using a 100% aqueous mobile phase for the LC separation. In addition, applications for measuring (13)C isotopic enrichments using atmospheric pressure LC-MS instruments with a quadrupole, a time-of-flight, and an ion trap analyzer are also discussed as well as a LC-ICPMS using a prototype instrument with two quadrupoles. PMID:17853432

  19. Evidence of 13C non-covalent isotope effects obtained by quantitative 13C nuclear magnetic resonance spectroscopy at natural abundance during normal phase liquid chromatography.

    PubMed

    Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Rojas, Jose Manuel Moreno; Guillou, Claude; Remaud, Gérald S

    2009-10-16

    Quantitative isotopic (13)C NMR at natural abundance has been used to determine the site-by-site (13)C/(12)C ratios in vanillin and a number of related compounds eluted from silica gel chromatography columns under similar conditions. Head-to-tail isotope fractionation is observed in all compounds at the majority of carbon positions. Furthermore, the site-specific isotope deviations show signatures characteristic of the position and functionality of the substituents present. The observed effects are more complex than would be obtained by simply summing the individual effects. Such detail is hidden when only the global (13)C content is measured by mass spectrometry. In particular, carbon positions within the aromatic ring are found to show site-specific isotope fractionation between the solute and the stationary phase. These interactions, defined as non-covalent isotope effects, can be normal or inverse and vary with the substitution pattern present. PMID:19748628

  20. Compound specific 13C- and 18O-isotope analysis of organic aerosols

    NASA Astrophysics Data System (ADS)

    Blees, Jan; Saurer, Matthias; Siegwolf, Rolf T. W.; Dommen, Josef; Baltensperger, Urs

    2014-05-01

    . Elements other than carbon may provide valuable additional information. Here we report on the development of methods for the analysis of stable carbon and oxygen isotope ratios of organic compounds in aerosols, through GC-combustion-irMS and GC-pyrolysis-irMS. We apply these analyses to environmental aerosol samples and samples of smog-chamber experiments, with the aim of identifying isotopic signatures of sources and pathways. We will pay special attention to derivatisation techniques - notably alternatives to the often-used trimethylsilyl derivatives in GC-pyrolysis-irMS for δ18O analysis - and to compound separation and identification. We present initial data of combined δ13C and δ18O studies on (secondary) organic aerosol samples, and their added value for source apportionment studies.

  1. Multi-Spectroscopic Analysis of Seed Quality and 13C-Stable-Iotopologue Monitoring in Initial Growth Metabolism of Jatropha curcas L.

    PubMed Central

    Komatsu, Takanori; Ohishi, Risa; Shino, Amiu; Akashi, Kinya; Kikuchi, Jun

    2014-01-01

    In the present study, we applied nuclear magnetic resonance (NMR), as well as near-infrared (NIR) spectroscopy, to Jatropha curcas to fulfill two objectives: (1) to qualitatively examine the seeds stored at different conditions, and (2) to monitor the metabolism of J. curcas during its initial growth stage under stable-isotope-labeling condition (until 15 days after seeding). NIR spectra could non-invasively distinguish differences in storage conditions. NMR metabolic analysis of water-soluble metabolites identified sucrose and raffinose family oligosaccharides as positive markers and gluconic acid as a negative marker of seed germination. Isotopic labeling patteren of metabolites in germinated seedlings cultured in agar-plate containg 13C-glucose and 15N-nitrate was analyzed by zero-quantum-filtered-total correlation spectroscopy (ZQF-TOCSY) and 13C-detected 1H-13C heteronuclear correlation spectroscopy (HETCOR). 13C-detected HETOCR with 13C-optimized cryogenic probe provided high-resolution 13C-NMR spectra of each metabolite in molecular crowd. The 13C-13C/12C bondmer estimated from 1H-13C HETCOR spectra indicated that glutamine and arginine were the major organic compounds for nitrogen and carbon transfer from roots to leaves. PMID:25401292

  2. Organic vs. Conventional Grassland Management: Do 15N and 13C Isotopic Signatures of Hay and Soil Samples Differ?

    PubMed Central

    Klaus, Valentin H.; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Fischer, Markus; Kleinebecker, Till

    2013-01-01

    Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ15N and δ13C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ15N (δ15N plant - δ15N soil) to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ13C in hay and δ15N in both soil and hay between management types, but showed that δ13C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ15N values implied that management types did not substantially differ in nitrogen cycling. Only δ13C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be efficiently used in practice

  3. Recent advances in mapping environmental microbial metabolisms through 13C isotopic fingerprints.

    PubMed

    Tang, Joseph Kuo-Hsiang; You, Le; Blankenship, Robert E; Tang, Yinjie J

    2012-11-01

    After feeding microbes with a defined (13)C substrate, unique isotopic patterns (isotopic fingerprints) can be formed in their metabolic products. Such labelling information not only can provide novel insights into functional pathways but also can determine absolute carbon fluxes through the metabolic network via metabolic modelling approaches. This technique has been used for finding pathways that may have been mis-annotated in the past, elucidating new enzyme functions, and investigating cell metabolisms in microbial communities. In this review paper, we summarize the applications of (13)C approaches to analyse novel cell metabolisms for the past 3 years. The isotopic fingerprints (defined as unique isotopomers useful for pathway identifications) have revealed the operations of the Entner-Doudoroff pathway, the reverse tricarboxylic acid cycle, new enzymes for biosynthesis of central metabolites, diverse respiration routes in phototrophic metabolism, co-metabolism of carbon nutrients and novel CO(2) fixation pathways. This review also discusses new isotopic methods to map carbon fluxes in global metabolisms, as well as potential factors influencing the metabolic flux quantification (e.g. metabolite channelling, the isotopic purity of (13)C substrates and the isotopic effect). Although (13)C labelling is not applicable to all biological systems (e.g. microbial communities), recent studies have shown that this method has a significant value in functional characterization of poorly understood micro-organisms, including species relevant for biotechnology and human health. PMID:22896564

  4. Recent advances in mapping environmental microbial metabolisms through 13C isotopic fingerprints

    PubMed Central

    Tang, Joseph Kuo-Hsiang; You, Le; Blankenship, Robert E.; Tang, Yinjie J.

    2012-01-01

    After feeding microbes with a defined 13C substrate, unique isotopic patterns (isotopic fingerprints) can be formed in their metabolic products. Such labelling information not only can provide novel insights into functional pathways but also can determine absolute carbon fluxes through the metabolic network via metabolic modelling approaches. This technique has been used for finding pathways that may have been mis-annotated in the past, elucidating new enzyme functions, and investigating cell metabolisms in microbial communities. In this review paper, we summarize the applications of 13C approaches to analyse novel cell metabolisms for the past 3 years. The isotopic fingerprints (defined as unique isotopomers useful for pathway identifications) have revealed the operations of the Entner–Doudoroff pathway, the reverse tricarboxylic acid cycle, new enzymes for biosynthesis of central metabolites, diverse respiration routes in phototrophic metabolism, co-metabolism of carbon nutrients and novel CO2 fixation pathways. This review also discusses new isotopic methods to map carbon fluxes in global metabolisms, as well as potential factors influencing the metabolic flux quantification (e.g. metabolite channelling, the isotopic purity of 13C substrates and the isotopic effect). Although 13C labelling is not applicable to all biological systems (e.g. microbial communities), recent studies have shown that this method has a significant value in functional characterization of poorly understood micro-organisms, including species relevant for biotechnology and human health. PMID:22896564

  5. Accurate quantitative 13C NMR spectroscopy: repeatability over time of site-specific 13C isotope ratio determination.

    PubMed

    Caytan, Elsa; Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Akoka, Serge; Remaud, Gérald S

    2007-11-01

    The stability over time (repeatability) for the determination of site-specific 13C/12C ratios at natural abundance by quantitative 13C NMR spectroscopy has been tested on three probes: enriched bilabeled [1,2-13C2]ethanol; ethanol at natural abundance; and vanillin at natural abundance. It is shown in all three cases that the standard deviation for a series of measurements taken every 2-3 months over periods between 9 and 13 months is equal to or smaller than the standard deviation calculated from 5-10 replicate measurements made on a single sample. The precision which can be achieved using the present analytical 13C NMR protocol is higher than the prerequisite value of 1-2 per thousand for the determination of site-specific 13C/12C ratios at natural abundance (13C-SNIF-NMR). Hence, this technique permits the discrimination of very small variations in 13C/12C ratios between carbon positions, as found in biogenic natural products. This observed stability over time in 13C NMR spectroscopy indicates that further improvements in precision will depend primarily on improved signal-to-noise ratio. PMID:17900175

  6. Isotopic variability of cave bears (δ15N, δ13C) across Europe during MIS 3

    NASA Astrophysics Data System (ADS)

    Krajcarz, Magdalena; Pacher, Martina; Krajcarz, Maciej T.; Laughlan, Lana; Rabeder, Gernot; Sabol, Martin; Wojtal, Piotr; Bocherens, Hervé

    2016-01-01

    Collagen, the organic fraction of bone, records the isotopic parameters of consumed food for carbon (δ13C) and nitrogen (δ15N). This relationship of isotopic signature between diet and tissue is an important tool for the study of dietary preferences of modern and fossil animal species. Since the first information on the isotopic signature of cave bear was reported, numerous data from Europe have become available. The goal of this work is to track the geographical variation of cave bear collagen isotopic values in Europe during Marine Isotopic Stage 3 (about 60,000-25,000 yr BP). In this study the results of new δ13C and δ15N isotopic analyses of cave bear collagen from four Central-Eastern European sites are presented, as well as a review of all published isotopic data for cave bears of the same period. The main conclusion is a lack of geographical East-West pattern in the variations of δ13C and δ15N values of cave bear collagen. Moreover, no relationship was found between cave bear taxonomy and isotopic composition. The cave bears from Central-Eastern Europe exhibit δ13C and δ15N values near the average of the range of Central, Western and Southern European cave bears. Despite the fact that most cave bear sites follow an altitudinal gradient, separate groups of sites exhibit shift in absolute values of δ13C, what disturbs an altitude-related isotopic pattern. The most distinct groups are: high Alpine sites situated over 1500 m a.s.l. - in terms of δ13C; and two Romanian sites Peştera cu Oase and Urşilor - in case of δ15N. Although the cave bear isotopic signature is driven by altitude, the altitudinal adjustment of isotopic data is not enough to explain the isotopic dissimilarity of these cave bears. The unusually high δ15N signature of mentioned Romanian sites is an isolated case in Europe. Cave bears from relatively closely situated Central-Eastern European sites and other Romanian sites are more similar to Western European than to Romanian

  7. Theoretical estimation of 13C-D clumped isotope effects in methyl of several organic compound

    NASA Astrophysics Data System (ADS)

    LIU, Q.; Yin, X.; Liu, Y.

    2015-12-01

    Recent developments in mass spectrometry and tunable infrared laser direct absorption spectroscopy make it possible to measure 13C-D clumped isotope effects of methane. These techniques can be further applied to determine 13C-D clumped isotope effects of methyl fragments, therefore need accurate equilirbium Δi values to calibrate experimental measurements. In this study, we calculate temperature depandences of 13C-D clumped isotope signatures in methyl of several organic compounds including ethane, propane, acetic acid, etc. Our calculation are performed at CCSD/6-311+G(3df,3pd) by using Gaussian 03 program with no scale treament. Our results show that the Δi values of 13C-D clumping in methyl fragments of different organic compounds yield similar signals (~5.5‰ at 25˚C, slightly lower than Δi value of 13C-D clumping in methane). For testing the calculated accuracy, theoretical treaments beyond the harmonic level by including several higher-order corrections to the Bigeleisen-Mayer equation are used. Contributions from higher-order corrections (e.g., AnZPE, AnEXC, VrZPE, VrEXC, QmCorr and CenDist) are estimated to repire the ignorings of the Bigeleisen-Mayer equation (the anharmonic effects of vibration, vibration-rotation coupling, quantum mechanics and centrifugal distortion for rotation, etc.) for the calculation of partition function ratios. The results show that the higher-order corrections contribute ~0.05‰ at 25˚C, which is similar to the contribution for calculating 13C-D clumped isotope signature of methane. By comparing our calculated frequencies to the measured ones, the uncertainty of our calculation of Δi values 13C-D clumping in methyl fragments is considered to be within ~0.05‰ at room temperature.

  8. Site-specific 13C content by quantitative isotopic 13C nuclear magnetic resonance spectrometry: a pilot inter-laboratory study.

    PubMed

    Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Pagelot, Alain; Moskau, Detlef; Moreno, Aitor; Schleucher, Jürgen; Reniero, Fabiano; Holland, Margaret; Guillou, Claude; Silvestre, Virginie; Akoka, Serge; Remaud, Gérald S

    2013-07-25

    Isotopic (13)C NMR spectrometry, which is able to measure intra-molecular (13)C composition, is of emerging demand because of the new information provided by the (13)C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic (13)C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular (13)C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic (13)C NMR was then assessed on vanillin from three different origins associated with specific δ (13)Ci profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ (13)Ci in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results. PMID:23845488

  9. Stable isotopes in mineralogy

    USGS Publications Warehouse

    O'Neil, J.R.

    1977-01-01

    Stable isotope fractionations between minerals are functions of the fundamental vibrational frequencies of the minerals and therefore bear on several topics of mineralogical interest. Isotopic compositions of the elements H, C, O, Si, and S can now be determined routinely in almost any mineral. A summary has been made of both published and new results of laboratory investigations, analyses of natural materials, and theoretical considerations which bear on the importance of temperature, pressure, chemical composition and crystal structure to the isotopic properties of minerals. It is shown that stable isotope studies can sometimes provide evidence for elucidating details of crystal structure and can be a powerful tool for use in tracing the reaction paths of mineralogical reactions. ?? 1977 Springer-Verlag.

  10. BIODEGRADATION OF FLUORANTHENE AS MONITORED USING STABLE CARBON ISOTOPES

    EPA Science Inventory

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

  11. The thermal desorption of CO2 from amine carbamate solutions for the 13C isotope enrichment

    NASA Astrophysics Data System (ADS)

    Dronca, S.; Varodi, C.; Gligan, M.; Stoia, V.; Baldea, A.; Hodor, I.

    2012-02-01

    The CO2 desorption from amine carbamate in non-aqueous solvents is of major importance for isotopic enrichment of 13C. A series of experiments were carried out in order to set up the conditions for the CO2 desorption. For this purpose, a laboratory- scale plant for 13C isotope separation by chemical exchange between CO2 and amine carbamate was designed and used. The decomposition of the carbamate solution was mostly produced in the desorber and completed in the boiler. Two different-length desorbers were used, at different temperatures and liquid flow rates of the amine-non-aqueous solvent solutions. The residual CO2 was determined by using volumetric and gaschromatographic methods. These results can be used for enrichment of 13C by chemical exchange between CO2 and amine carbamate in nonaqueous solvents.

  12. Conditions to obtain precise and true measurements of the intramolecular 13C distribution in organic molecules by isotopic 13C nuclear magnetic resonance spectrometry.

    PubMed

    Bayle, Kevin; Gilbert, Alexis; Julien, Maxime; Yamada, Keita; Silvestre, Virginie; Robins, Richard J; Akoka, Serge; Yoshida, Naohiro; Remaud, Gérald S

    2014-10-10

    Intramolecular (13)C composition gives access to new information on the (bio) synthetic history of a given molecule. Isotopic (13)C NMR spectrometry provides a general tool for measuring the position-specific (13)C content. As an emerging technique, some aspects of its performance are not yet fully delineated. This paper reports on (i) the conditions required to obtain satisfactory trueness and precision for the determination of the internal (13)C distribution, and (ii) an approach to determining the "absolute" position-specific (13)C content. In relation to (i), a precision of <1% can be obtained whatever the molecule on any spectrometer, once quantitative conditions are met, in particular appropriate proton decoupling efficiency. This performance is a prerequisite to the measurement of isotope fractionation either on the transformed or residual compound when a chemical reaction or process is being studied. The study of the trueness has revealed that the response of the spectrometer depends on the (13)C frequency range of the studied molecule, i.e. the chemical shift range. The "absolute value" and, therefore, the trueness of the (13)C NMR measurements has been assessed on acetic acid and by comparison to the results obtained on the fragments from COOH and CH3 by isotopic mass spectrometry coupled to a pyrolysis device (GC-Py-irm-MS), this technique being the reference method for acetic acid. Of the two NMR spectrometers used in this work, one gave values that corresponded to those obtained by GC-Py-irm-MS (thus, the "true" value) while the other showed a bias, which was dependent to the range covered by the resonance frequencies of the molecule. Therefore, the former can be used directly for studying isotope affiliations, while the latter can only be used directly for comparative data, for example in authenticity studies, but can also be used to obtain the true values by applying appropriate correction factors. The present study assesses several key protocol

  13. Validating the Incorporation of 13C and 15N in a Shorebird That Consumes an Isotopically Distinct Chemosymbiotic Bivalve

    PubMed Central

    van Gils, Jan A.; Ahmedou Salem, Mohamed Vall

    2015-01-01

    The wealth of field studies using stable isotopes to make inferences about animal diets require controlled validation experiments to make proper interpretations. Despite several pleas in the literature for such experiments, validation studies are still lagging behind, notably in consumers dwelling in chemosynthesis-based ecosystems. In this paper we present such a validation experiment for the incorporation of 13C and 15N in the blood plasma of a medium-sized shorebird, the red knot (Calidris canutus canutus), consuming a chemosymbiotic lucinid bivalve (Loripes lucinalis). Because this bivalve forms a symbiosis with chemoautotrophic sulphide-oxidizing bacteria living inside its gill, the bivalve is isotopically distinct from ‘normal’ bivalves whose food has a photosynthetic basis. Here we experimentally tested the hypothesis that isotope discrimination and incorporation dynamics are different when consuming such chemosynthesis-based prey. The experiment showed that neither the isotopic discrimination factor, nor isotopic turnover time, differed between birds consuming the chemosymbiotic lucinid and a control group consuming a photosynthesis-based bivalve. This was true for 13C as well as for 15N. However, in both groups the 15N discrimination factor was much higher than expected, which probably had to do with the birds losing body mass over the course of the experiment. PMID:26458005

  14. Validating the Incorporation of 13C and 15N in a Shorebird That Consumes an Isotopically Distinct Chemosymbiotic Bivalve.

    PubMed

    van Gils, Jan A; Ahmedou Salem, Mohamed Vall

    2015-01-01

    The wealth of field studies using stable isotopes to make inferences about animal diets require controlled validation experiments to make proper interpretations. Despite several pleas in the literature for such experiments, validation studies are still lagging behind, notably in consumers dwelling in chemosynthesis-based ecosystems. In this paper we present such a validation experiment for the incorporation of 13C and 15N in the blood plasma of a medium-sized shorebird, the red knot (Calidris canutus canutus), consuming a chemosymbiotic lucinid bivalve (Loripes lucinalis). Because this bivalve forms a symbiosis with chemoautotrophic sulphide-oxidizing bacteria living inside its gill, the bivalve is isotopically distinct from 'normal' bivalves whose food has a photosynthetic basis. Here we experimentally tested the hypothesis that isotope discrimination and incorporation dynamics are different when consuming such chemosynthesis-based prey. The experiment showed that neither the isotopic discrimination factor, nor isotopic turnover time, differed between birds consuming the chemosymbiotic lucinid and a control group consuming a photosynthesis-based bivalve. This was true for 13C as well as for 15N. However, in both groups the 15N discrimination factor was much higher than expected, which probably had to do with the birds losing body mass over the course of the experiment. PMID:26458005

  15. OpenMebius: An Open Source Software for Isotopically Nonstationary 13C-Based Metabolic Flux Analysis

    PubMed Central

    Furusawa, Chikara

    2014-01-01

    The in vivo measurement of metabolic flux by 13C-based metabolic flux analysis (13C-MFA) provides valuable information regarding cell physiology. Bioinformatics tools have been developed to estimate metabolic flux distributions from the results of tracer isotopic labeling experiments using a 13C-labeled carbon source. Metabolic flux is determined by nonlinear fitting of a metabolic model to the isotopic labeling enrichment of intracellular metabolites measured by mass spectrometry. Whereas 13C-MFA is conventionally performed under isotopically constant conditions, isotopically nonstationary 13C metabolic flux analysis (INST-13C-MFA) has recently been developed for flux analysis of cells with photosynthetic activity and cells at a quasi-steady metabolic state (e.g., primary cells or microorganisms under stationary phase). Here, the development of a novel open source software for INST-13C-MFA on the Windows platform is reported. OpenMebius (Open source software for Metabolic flux analysis) provides the function of autogenerating metabolic models for simulating isotopic labeling enrichment from a user-defined configuration worksheet. Analysis using simulated data demonstrated the applicability of OpenMebius for INST-13C-MFA. Confidence intervals determined by INST-13C-MFA were less than those determined by conventional methods, indicating the potential of INST-13C-MFA for precise metabolic flux analysis. OpenMebius is the open source software for the general application of INST-13C-MFA. PMID:25006579

  16. Position-Specific Isotope Analysis of Xanthines: A (13)C Nuclear Magnetic Resonance Method to Determine the (13)C Intramolecular Composition at Natural Abundance.

    PubMed

    Diomande, Didier G; Martineau, Estelle; Gilbert, Alexis; Nun, Pierrick; Murata, Ariaki; Yamada, Keita; Watanabe, Naoharu; Tea, Illa; Robins, Richard J; Yoshida, Naohiro; Remaud, Gérald S

    2015-07-01

    The natural xanthines caffeine, theobromine, and theophylline are of major commercial importance as flavor constituents in coffee, cocoa, tea, and a number of other beverages. However, their exploitation for authenticity, a requirement in these commodities that have a large origin-based price-range, by the standard method of isotope ratio monitoring by mass spectrometry (irm-MS) is limited. We have now developed a methodology that overcomes this deficit that exploits the power of isotopic quantitative (13)C nuclear magnetic resonance (NMR) spectrometry combined with chemical modification of the xanthines to enable the determination of positional intramolecular (13)C/(12)C ratios (δ(13)Ci) with high precision. However, only caffeine is amenable to analysis: theobromine and theophylline present substantial difficulties due to their poor solubility. However, their N-methylation to caffeine makes spectral acquisition feasible. The method is confirmed as robust, with good repeatability of the δ(13)Ci values in caffeine appropriate for isotope fractionation measurements at natural abundance. It is shown that there is negligible isotope fractionation during the chemical N-methylation procedure. Thus, the method preserves the original positional δ(13)Ci values. The method has been applied to measure the position-specific variation of the (13)C/(12)C distribution in caffeine. Not only is a clear difference between caffeine isolated from different sources observed, but theobromine from cocoa is found to show a (13)C pattern distinct from that of caffeine. PMID:26067163

  17. Forensic Stable Isotope Biogeochemistry

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  18. Quantitative microbial ecology through stable isotope probing.

    PubMed

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

    2015-11-01

    Bacteria grow and transform elements at different rates, and as yet, quantifying this variation in the environment is difficult. Determining isotope enrichment with fine taxonomic resolution after exposure to isotope tracers could help, but there are few suitable techniques. We propose a modification to stable isotope probing (SIP) that enables the isotopic composition of DNA from individual bacterial taxa after exposure to isotope tracers to be determined. In our modification, after isopycnic centrifugation, DNA is collected in multiple density fractions, and each fraction is sequenced separately. Taxon-specific density curves are produced for labeled and nonlabeled treatments, from which the shift in density for each individual taxon in response to isotope labeling is calculated. Expressing each taxon's density shift relative to that taxon's density measured without isotope enrichment accounts for the influence of nucleic acid composition on density and isolates the influence of isotope tracer assimilation. The shift in density translates quantitatively to isotopic enrichment. Because this revision to SIP allows quantitative measurements of isotope enrichment, we propose to call it quantitative stable isotope probing (qSIP). We demonstrated qSIP using soil incubations, in which soil bacteria exhibited strong taxonomic variations in (18)O and (13)C composition after exposure to [(18)O]water or [(13)C]glucose. The addition of glucose increased the assimilation of (18)O into DNA from [(18)O]water. However, the increase in (18)O assimilation was greater than expected based on utilization of glucose-derived carbon alone, because the addition of glucose indirectly stimulated bacteria to utilize other substrates for growth. This example illustrates the benefit of a quantitative approach to stable isotope probing. PMID:26296731

  19. Monitoring CO2 concentration and δ13C in an underground cavity using a commercial isotope ratio infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Guillon, Sophie; Agrinier, Pierre; Pili, Éric

    2015-04-01

    CO2 stable carbon isotopes are very attractive in environmental research to investigate both natural and anthropogenic carbon sources. Laser-based isotope ratio infrared spectrometers (IRIS) allow in situ continuous monitoring of CO2 isotopes, and therefore they have a potential for unprecedented understanding of carbon sources and dynamics with a high temporal resolution. Here we present the performance assessment of a commercial IRIS analyzer, including the measurement setup and the data processing scheme that we used. Even if the analyzer performs 1-Hz measurements, an integration time of the order of 1 h is commonly needed to obtain acceptable precision for δ13C. The main sources of uncertainty on δ13C come from the concentration dependence and from the temporal instability of the analyzer. The method is applied to the in situ monitoring of the CO2 carbon isotopes in an underground cavity (Roselend Natural Laboratory, France) during several months. On a weekly timescale, the temporal variability of CO2 is dominated by transient contamination by human breath. Discarding these anthropogenic contaminations, CO2 and δ13C backgrounds do not show diurnal or seasonal fluctuations. A CO2 flux released into the tunnel by the surrounding rocks is measured. The carbon isotope composition of this CO2, identified with a Keeling plot, is consistent with a main production by microbial respiration and a minor production from weathering of carbonate minerals. The presented instrument and application study are relevant to cave monitoring, whether to understand CO2 dynamics in visited and/or painted caves for preservation purposes or to understand paleoclimate recording in speleothems.

  20. Photobioreactor design for isotopic non-stationary 13C-metabolic flux analysis (INST 13C-MFA) under photoautotrophic conditions.

    PubMed

    Martzolff, Arnaud; Cahoreau, Edern; Cogne, Guillaume; Peyriga, Lindsay; Portais, Jean-Charles; Dechandol, Emmanuel; Le Grand, Fabienne; Massou, Stéphane; Gonçalves, Olivier; Pruvost, Jérémy; Legrand, Jack

    2012-12-01

    Adaptive metabolic behavior of photoautotrophic microorganisms toward genetic and environmental perturbations can be interpreted in a quantitative depiction of carbon flow through a biochemical reaction network using isotopic non-stationary (13) C-metabolic flux analysis (INST (13) C-MFA). To evaluate (13) C-metabolic flux maps for Chlamydomonas reinhardtii, an original experimental framework was designed allowing rapid, reliable collection of high-quality isotopomer data against time. It involved (i) a short-time (13) C labeling injection device based on mixing control in a torus-shaped photobioreactor with plug-flow hydrodynamics allowing a sudden step-change in the (13) C proportion in the substrate feed and (ii) a rapid sampling procedure using an automatic fast filtration method coupled to a manual rapid liquid nitrogen quenching step. (13) C-substrate labeling enrichment was controlled through the total dissolved inorganic carbon concentration in the pulsed solution. First results were obtained from steady-state continuous culture measurements allowing the characterization of the kinetics of label incorporation into light-limited growing cells cultivated in a photobioreactor operating at the maximal biomass productivity for an incident photon flux density of 200 µmol m(-2) s(-1). (13)C label incorporation was measured for 21 intracellular metabolites using IC-MS/MS in 58 samples collected across a labeling experiment duration of 7 min. The fastest labeling rate was observed for 2/3-phosphoglycerate with an apparent isotopic stationary state reached after 300 s. The labeling rate was consistent with the optimized mixing time of about 4.9 s inside the reactor and the shortest reliable sampling period assessed at 5 s. PMID:22688667

  1. Comparing isotope signatures of prey fish: does gut removal affect δ13C or δ15N?

    USGS Publications Warehouse

    Chipps, Steven R.; Fincel, Mark J.; VanDeHey, Justin A.; Wuestewald, Andrew

    2011-01-01

    Stable isotope analysis is a quick and inexpensive method to monitor the effects of food web changes on aquatic communities. Traditionally, whole specimens have been used when determining isotope composition of prey fish or age-0 recreational fishes. However, gut contents of prey fish could potentially alter isotope composition of the specimen, especially when recent foraging has taken place or when the gut contains non-assimilated material that would normally pass through fishes undigested. To assess the impacts of gut content on prey fish isotope signatures, we examined the differences in isotopic variation of five prey fish species using whole fish, whole fish with the gut contents removed, and dorsal muscle only. We found significant differences in both δ15N and δ13C between the three tissue treatments. In most cases, muscle tissue was enriched compared to whole specimens or gut-removed specimens. Moreover, differences in mean δ15N within a species were up to 2‰ among treatments. This would result in a change of over half a trophic position (TP) based on a 3.4‰ increase per trophic level. However, there were no apparent relationships between tissue isotope values in fish with increased gut fullness (more prey tissue present). We suggest that muscle tissue should be used as the standard tissue for determining isotope composition of prey fish or age-0 recreational fishes, especially when determining enrichment for mixing models, calculating TP, or constructing aquatic food webs.

  2. Analysis of dissolved organic carbon concentration and 13C isotopic signature by TOC-IRMS - assessment of analytical performance

    NASA Astrophysics Data System (ADS)

    Kirkels, Frédérique; Cerli, Chiara; Federherr, Eugen; Kalbitz, Karsten

    2013-04-01

    Stable carbon isotopes provide a powerful tool to assess carbon pools and their dynamics. Dissolved organic carbon (DOC) has been recognized to play an important role in ecosystem functioning and carbon cycling and has therefore gained increased research interest. However, direct measurement of 13C isotopic signature of carbon in the dissolved phase is technically challenging particularly using high temperature combustion. Until recently, mainly custom-made systems existed which were modified for coupling of TOC instruments with IRMS for simultaneous assessment of C content and isotopic signature. The variety of coupled systems showed differences in their analytical performances. For analysis of DOC high temperature combustion is recognized as best performing method, owing to its high efficiency of conversion to CO2 also for highly refractory components (e.g. humic, fulvic acids) present in DOC and soil extracts. Therefore, we tested high temperature combustion TOC coupled to IRMS (developed by Elementar Group) for bulk measurements of DOC concentration and 13C signature. The instruments are coupled via an Interface to exchange the carrier gas from O2 to He and to concentrate the derived CO2 for the isotope measurement. Analytical performance of the system was assessed for a variety of organic compounds characterized by different stability and complexity, including humic acid and DOM. We tested injection volumes between 0.2-3 ml, thereby enabling measurement of broad concentration ranges. With an injection volume of 0.5 ml (n=3, preceded by 1 discarded injection), DOC and 13C signatures for concentrations between 5-150 mg C/L were analyzed with high precision (standard deviation (SD) predominantly <0.1‰), good accuracy and linearity (overall SD <0.9‰). For the same settings, slightly higher variation in precision was observed among the lower concentration range and depending upon specific system conditions. Differences in 13C signatures of about 50‰ among

  3. Quantitative analysis of deuterium using the isotopic effect on quaternary (13)C NMR chemical shifts.

    PubMed

    Darwish, Tamim A; Yepuri, Nageshwar Rao; Holden, Peter J; James, Michael

    2016-07-13

    Quantitative analysis of specifically deuterated compounds can be achieved by a number of conventional methods, such as mass spectroscopy, or by quantifying the residual (1)H NMR signals compared to signals from internal standards. However, site specific quantification using these methods becomes challenging when dealing with non-specifically or randomly deuterated compounds that are produced by metal catalyzed hydrothermal reactions in D2O, one of the most convenient deuteration methods. In this study, deuterium-induced NMR isotope shifts of quaternary (13)C resonances neighboring deuterated sites have been utilized to quantify the degree of isotope labeling of molecular sites in non-specifically deuterated molecules. By probing (13)C NMR signals while decoupling both proton and deuterium nuclei, it is possible to resolve (13)C resonances of the different isotopologues based on the isotopic shifts and the degree of deuteration of the carbon atoms. We demonstrate that in different isotopologues, the same quaternary carbon, neighboring partially deuterated carbon atoms, are affected to an equal extent by relaxation. Decoupling both nuclei ((1)H, (2)H) resolves closely separated quaternary (13)C signals of the different isotopologues, and allows their accurate integration and quantification under short relaxation delays (D1 = 1 s) and hence fast accumulative spectral acquisition. We have performed a number of approaches to quantify the deuterium content at different specific sites to demonstrate a convenient and generic analysis method for use in randomly deuterated molecules, or in cases of specifically deuterated molecules where back-exchange processes may take place during work up. PMID:27237841

  4. Understanding carbon isotope behaviour during combustion processes: a pre-requisite to using d13C in the field of air pollution.

    NASA Astrophysics Data System (ADS)

    Negrel, P.; Widory, D.

    2006-12-01

    Recent studies have demonstrated the effectiveness of stable isotopes in the field of air pollution research, especially their success in clearly discriminating the different sources of pollution in urban environments, and in tracing their respective impacts for a given sampling location. Among them, carbon isotopes have been used to track the origin of both gases (i.e. CO2; Widory &Javoy, 2003) and particulate matter (i.e. PM2 .5 and PM10; Widory et al., 2004). But understanding the carbon isotope behaviour that leads to this discrimination during combustion processes is a pre-requisite to using them as tracers of pollution sources in the atmosphere. d13C in fuels has been extensively used as an indicator of the processes leading to the generation of their parent crude-oil. Here, we isotopically characterise fuels and combustibles sold in Paris (France), and characterise the isotopic relations existing with their combustion by-products, i.e. gases (CO2) and particles (bulk carbon). Results show that d13C in fuels is clearly related to their physical state, with natural gas being strongly depleted in 13C while coal yields the highest d13C, and liquid fuels display intermediate values. This relation is also valid for exhaust gases, though d13C values of combustion particles form a homogeneous range within which no clear distinction is observed. Combustion processes are accompanied by carbon-isotope fractionation resulting from the combustion being incomplete. Carbon-isotope fractionation is strictly negative ( 1.3‰) during the formation of combustion gases, but generally positive in particle formation even if values close to zero are observed. This study helps understanding the processes leading to the d13C discrimination observed in pollution sources' exhausts, and definitely validates the use of carbon isotopes as tracers of atmospheric pollution.

  5. Measurement of position-specific 13C isotopic composition of propane at the nanomole level

    NASA Astrophysics Data System (ADS)

    Gilbert, Alexis; Yamada, Keita; Suda, Konomi; Ueno, Yuichiro; Yoshida, Naohiro

    2016-03-01

    We have developed a novel method for analyzing intramolecular carbon isotopic distribution of propane as a potential new tracer of its origin. The method is based on on-line pyrolysis of propane followed by analysis of carbon isotope ratios of the pyrolytic products methane, ethylene and ethane. Using propane samples spiked with 13C at the terminal methyl carbon, we characterize the origin of the pyrolytic fragments. We show that the exchange between C-atoms during the pyrolytic process is negligible, and thus that relative intramolecular isotope composition can be calculated. Preliminary data from 3 samples show that site-preference (SP) values, defined as the difference of δ13C values between terminal and sub-terminal C-atom positions of propane, range from -1.8‰ to -12.9‰. In addition, SP value obtained using our method for a thermogenic natural gas sample is consistent with that expected from theoretical models of thermal cracking, suggesting that the isotope fractionation associated with propane pyrolysis is negligible. The method will provide novel insights into the characterization of the origin of propane and will help better understand the biogeochemistry of natural gas deposits.

  6. Aspects regarding at 13C isotope separation column control using Petri nets system

    NASA Astrophysics Data System (ADS)

    Boca, M. L.; Ciortea, M. E.

    2015-11-01

    This paper is intended to show that Petri nets can be also applicable in the chemical industry. It used linear programming, modeling underlying Petri nets, especially discrete event systems for isotopic separation, the purpose of considering and control events in real-time through graphical representations. In this paper it is simulate the control of 13C Isotope Separation column using Petri nets. The major problem with 13C comes from the difficulty of obtaining it and raising its natural fraction. Carbon isotopes can be obtained using many methods, one of them being the cryogenic distillation of carbon monoxide. Some few aspects regarding operating conditions and the construction of such cryogenic plants are known today, and even less information are available as far as the separation process modeling and control are concerned. In fact, the efficient control of the carbon monoxide distillation process represents a necessity for large-scale 13C production. Referring to a classic distillation process, some models for carbon isotope separation have been proposed, some based on mass, component and energy balance equations, some on the nonlinear wave theory or the Cohen equations. For modeling the system it was used Petri nets because in this case it is deal with discrete event systems. In use of the non-timed and with auxiliary times Petri model, the transport stream was divided into sections and these sections will be analyzed successively. Because of the complexity of the system and the large amount of calculations required it was not possible to analyze the system as a unitary whole. A first attempt to model the system as a unitary whole led to the blocking of the model during simulation, because of the large processing times.

  7. Intraskeletal isotopic compositions (δ(13) C, δ(15) N) of bone collagen: nonpathological and pathological variation.

    PubMed

    Olsen, Karyn C; White, Christine D; Longstaffe, Fred J; von Heyking, Kristin; McGlynn, George; Grupe, Gisela; Rühli, Frank J

    2014-04-01

    Paleodiet research traditionally interprets differences in collagen isotopic compositions (δ(13) C, δ(15) N) as indicators of dietary distinction even though physiological processes likely play some role in creating variation. This research investigates the degree to which bone collagen δ(13) C and δ(15) N values normally vary within the skeleton and examines the influence of several diseases common to ancient populations on these isotopic compositions. The samples derive from two medieval German cemeteries and one Swiss reference collection and include examples of metabolic disease (rickets/osteomalacia), degenerative joint disease (osteoarthritis), trauma (fracture), infection (osteomyelitis), and inflammation (periostitis). A separate subset of visibly nonpathological skeletal elements from the German collections established normal intraindividual variation. For each disease type, tests compared bone lesion samples to those near and distant to the lesions sites. Results show that normal (nonpathological) skeletons exhibit limited intraskeletal variation in carbon- and nitrogen-isotope ratios, suggesting that sampling of distinct elements is appropriate for paleodiet studies. In contrast, individuals with osteomyelitis, healed fractures, and osteoarthritis exhibit significant intraskeletal differences in isotope values, depending on whether one is comparing lesions to near or to distant sites. Skeletons with periostitis result in significant intraskeletal differences in nitrogen isotope values only, while those with rickets/osteomalacia do not exhibit significant intraskeletal differences. Based on these results, we suggest that paleodiet researchers avoid sampling collagen at or close to lesion sites because the isotope values may be reflecting both altered metabolic processes and differences in diet relative to others in the population. PMID:24374993

  8. Do birds of like feather flock together? The use of a novel 13C+D combustion isotope analyzer to track bird migration

    NASA Astrophysics Data System (ADS)

    Saad, N.

    2011-12-01

    Information on spring migration routes, geographic linkages among winter, spring, and breeding locations, and potential geographic effects on arrival body condition of a variety of avian species is so far little known. Stable isotope ratios are exquisitely sensitive to the biochemistry of living organisms and the nutrients available to them. Isotope ratios provide detailed knowledge useful in a variety of fields, including birds migration, through a combination of stable-isotope measurements of carbon (13C/12C) and hydrogen (D/H) isotopes of flight feathers and breast feathers of tissues representing different periods of dietary integration and body composition analyses. Associations among specific geographic areas, habitat use, and arrival condition can be elucidated through the measurement of these dual isotopes. We report here on the development of a novel laser spectroscopy based system for the simultaneous analysis of the stable isotope ratios of carbon (13C/12C) and hydrogen (D/H) that is robust, easy-to-use, and is the first stable isotope ratio analysis system to combine the measurement of 13C/12C and D/H in one simple analysis from a bulk organic sample with an application to bird migration. The system comprises a combustion module to convert the organic sample into CO2 and H2O and a Cavity Ring-Down Spectrometer (CRDS) that analyzes the combustion species inside an optical cavity based on the molecular absorption of individual isotopomers. This CRDS uses dual lasers to target the four isotpomers of interest: 12CO2, 13CO2, H2O and HDO. The system delivers a typical precision of 0.1 permil for δ13C and 1.5 permil for δD that parallels that achieved by IRMS, but with an unprecedented simplicity that allows ecologists to leverage the science and elucidate the avian migration patterns.

  9. Protein stable isotope fingerprinting: multidimensional protein chromatography coupled to stable isotope-ratio mass spectrometry.

    PubMed

    Mohr, Wiebke; Tang, Tiantian; Sattin, Sarah R; Bovee, Roderick J; Pearson, Ann

    2014-09-01

    Protein stable isotope fingerprinting (P-SIF) is a method to measure the carbon isotope ratios of whole proteins separated from complex mixtures, including cultures and environmental samples. The goal of P-SIF is to expose the links between taxonomic identity and metabolic function in microbial ecosystems. To accomplish this, two dimensions of chromatography are used in sequence to resolve a sample containing ca. 5-10 mg of mixed proteins into 960 fractions. Each fraction then is split in two aliquots: The first is digested with trypsin for peptide sequencing, while the second has its ratio of (13)C/(12)C (value of δ(13)C) measured in triplicate using an isotope-ratio mass spectrometer interfaced with a spooling wire microcombustion device. Data from cultured species show that bacteria have a narrow distribution of protein δ(13)C values within individual taxa (±0.7-1.2‰, 1σ). This is moderately larger than the mean precision of the triplicate isotope measurements (±0.5‰, 1σ) and may reflect heterogeneous distribution of (13)C among the amino acids. When cells from different species are mixed together prior to protein extraction and separation, the results can predict accurately (to within ±1σ) the δ(13)C values of the original taxa. The number of data points required for this endmember prediction is ≥20/taxon, yielding a theoretical resolution of ca. 10 taxonomic units/sample. Such resolution should be useful to determine the overall trophic breadth of mixed microbial ecosystems. Although we utilize P-SIF to measure natural isotope ratios, it also could be combined with experiments that incorporate stable isotope labeling. PMID:25121924

  10. Carbon isotope ratio (13C/12C) of pine honey and detection of HFCS adulteration.

    PubMed

    Çinar, Serap B; Ekşi, Aziz; Coşkun, İlknur

    2014-08-15

    Carbon isotope ratio ((13)C/(12)C=δ(13)C) of 100 pine honey samples collected from 9 different localities by Mugla region (Turkey) in years 2006, 2007 and 2008 were investigated. The δ(13)Cprotein value of honey samples ranged between -23.7 and -26.6‰, while the δ(13)Choney value varied between -22.7 and -27‰. For 90% of the samples, the difference in the C isotope ratio of protein and honey fraction (δ(13)Cpro-δ(13)Chon) was -1.0‰ and/or higher. Therefore, it can be said that the generally anticipated minimum value of C isotope difference (-1.0‰) for honey is also valid for pine honey. On the other hand, C4 sugar value (%), which was calculated from the δ(13)Cpro-δ(13)Chon difference, was found to be linearly correlated with the amount of adulterant (HFCS) in pine honey. These results indicate that C4 sugar value is a powerful criteria for detecting HFCS adulteration in pine honey. The δ(13)Choney and δ(13)Cprotein-δ(13)Choney values of the samples did not show any significant differences in terms of both year and locality (P>0.05), while the δ(13)Cprotein values showed significant differences due to year (P<0.05) but not due to locality (P>0.05). PMID:24679745

  11. Stable isotope laser spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  12. Stable isotope laser spectroscopy

    NASA Astrophysics Data System (ADS)

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

    1989-03-01

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

  13. Re-evaluating the isotopic divide between angiosperms and gymnosperms using n-alkane δ13C values

    NASA Astrophysics Data System (ADS)

    Bush, R. T.; McInerney, F. A.

    2009-12-01

    Angiosperm δ13C values are typically 1-3‰ more negative than those of co-occurring gymnosperms. This is known for both bulk leaf and compound-specific values from n-alkanes, which are stable, straight-chain hydrocarbons (C23-C35) found in the epicuticular leaf wax of vascular plants. For n-alkanes, there is a second distinction between the δ13C values of angiosperms and gymnosperms—δ13C values generally decrease with increasing chain-length in angiosperms, while in gymnosperms they increase. These two distinctions have been used to support the ‘plant community change hypothesis’ explaining the difference between the terrestrial and marine carbon isotope excursions during the Paleocene-Eocene Thermal Maximum (PETM.) Preserved n-alkanes from terrestrial paleosols in the Bighorn Basin, Wyoming reveal a negative carbon isotope excursion during the PETM of 4-5‰, which is 1-2‰ greater than the excursion recorded by marine carbonates. The local plant community, known from macrofossils as well as palynoflora, shifted from a deciduous, mixed angiosperm/gymnosperm flora to a suite of evergreen angiosperm species during the PETM. At the end of the PETM, the community returned to a mixed deciduous flora very similar to the original. This change in the plant community could thus magnify the terrestrial negative carbon isotope excursion to the degree necessary to explain its divergence from the marine record. However, the comparison between modern angiosperms and gymnosperms has been made mostly between broadleaf, deciduous angiosperms and evergreen, coniferous gymnosperms. New data analyzing deciduous, coniferous gymnosperms, including Metasequoia glyptostroboides and Taxodium distichum, suggests that the division previously ascribed to taxonomy may actually be based on leaf habit and physiology, specifically broadleaf, deciduous versus needle-leaf, evergreen plants. If differences in n-alkane δ13C values can be described not as angiosperms versus gymnosperms

  14. Thz Spectroscopy of 13C Isotopic Species of a "weed": Acetaldehyde

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R. A.; Guillemin, J.-C.

    2011-06-01

    Our studies of the isotopic species of 13C and D isotopologues of methyl formate (HCOOCH_3), have allowed the detection of more than 600 lines in Orion. This confirms that many observed U-lines are coming from isotopic species of one of the most abundant molecules in space. Since its first detection in 1976 in SgrB2 and in Orion A, acetaldehyde (CH_3CHO) was detected in many other numerous objects. If its deuterated species (CD_3CHO and CH_3CDO) have been previously studied in the millimeterwave range, the data concerning the 13C species are limited to few lines measured in 1957 up to 40 GHz. In this context we decided to study the 13C species of acetaldehyde. Acetaldehyde molecule displays a large amplitude motion: the hindered rotation of the methyl group with respect to the rest of the molecule. The analysis is performed with the Rho Axis Method. Recent versions of the codes include high orders term in order to reproduce the observed frequencies for large quantum numbers values as J-values as high as 70a,b,. Measurements and analysis of the rotational spectra of 13C isotopic species are in progress in Lille with a solid-state submillimetre-wave spectrometer (50-950 GHz), the first results will be presented. This work is supported by the contract ANR-08-BLAN-0054 and by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS). Carvajal, M.; Margulès, L.; Tercero, B.; et al.A&A 500, (2009) 1109 Margulès, L.; Huet, T. R.; Demaison J.; et al.,ApJ 714, (2010) 1120. Ikeda, M.; Ohishi, M.; Nummelin, A.; et al., ApJ, 560, (2001) 792 Kleiner, I.; Lopez, J.-C.; Blanco, S.; et al.J. Mol. Spectrosc. 197, (1999) 275 Elkeurti M.; Coudert, L. H.; Medvedev, I. R.; et al.J. Mol. Spectrosc. 263, (2010) 145 Kilb, R.W.; Lin, C.C.; and Wilson, E.B.J. Chem. Phys. 26, (1957) 1695 Kleiner, I. J. Mol. Spectrosc. 260, (2010) 1 Ilyushin, V.V.; Kryvda, A; and Alekseev, E;J. Mol. Spectrosc. 255, (2009) 32

  15. Partial 13C isotopic enrichment of nucleoside monophosphates: useful reporters for NMR structural studies

    PubMed Central

    Kishore, Anita I.; Mayer, Michael R.; Prestegard, James H.

    2005-01-01

    Analysis of the 13C isotopic labeling patterns of nucleoside monophosphates (NMPs) extracted from Escherichia coli grown in a mixture of C-1 and C-2 glucose is presented. By comparing our results to previous observations on amino acids grown in similar media, we have been able to rationalize the labeling pattern based on the well-known biochemistry of nucleotide biosynthesis. Except for a few notable absences of label (C4 in purines and C3′ in ribose) and one highly enriched site (C1′ in ribose), most carbons are randomly enriched at a low level (an average of 13%). These sparsely labeled NMPs give less complex NMR spectra than their fully isotopically labeled analogs due to the elimination of most 13C–13C scalar couplings. The spectral simplicity is particularly advantageous when working in ordered systems, as illustrated with guanosine diphosphate (GDP) bound to ADP ribosylation factor 1 (ARF1) aligned in a liquid crystalline medium. In this system, the absence of scalar couplings and additional long-range dipolar couplings significantly enhances signal to noise and resolution. PMID:16254075

  16. sup 13 C and sup 18 O isotopic disequilibrium in biological carbonates: II. In vitro simulation of kinetic isotope effects

    SciTech Connect

    McConnaughey, T. )

    1989-01-01

    Biological carbonates are built largely from CO{sub 2}, which diffuses across the skeletogenic membrane and reacts to form HCO{sub 3}{sup {minus}}. Kinetic discrimination against the heavy isotopes {sup 18}O and {sup 13}C during CO{sub 2} hydration and hydroxylation apparently causes most of the isotopic disequilibrium observed in biological carbonates. These kinetic isotope effects are expressed when the extracytosolic calcifying solution is thin and alkaline, and HCO{sub 3}{sup {minus}} precipitates fairly rapidly as CaCO{sub 3}. In vitro simulation of the calcifying environment produced heavy isotope depletions qualitatively similar to, but somewhat more extreme than, those seen in biological carbonates. Isotopic equilibration during biological calcification occurs through CO{sub 2} exchange across the calcifying membrane and by admixture ambient waters (containing HCO{sub 3}{sup {minus}}) into the calcifying fluids. Both mechanisms tend to produce linear correlations between skeletal {delta}{sup 13}C and {delta}{sup 18}O.

  17. Ca and Mg isotope constraints on the origin of Earth's deepest δ13 C excursion

    NASA Astrophysics Data System (ADS)

    Husson, Jon M.; Higgins, John A.; Maloof, Adam C.; Schoene, Blair

    2015-07-01

    Understanding the extreme carbon isotope excursions found in carbonate rocks of the Ediacaran Period (635-541 Ma), where δ13 C of marine carbonates (δ13 Ccarb) reach their minimum (- 12 ‰) for Earth history, is one of the most vexing problems in Precambrian geology. Known colloquially as the 'Shuram' excursion, the event has been interpreted by many as a product of a profoundly different Ediacaran carbon cycle. More recently, diagenetic processes have been invoked, with the very negative δ13 C values of Ediacaran carbonates explained via meteoric alteration, late-stage burial diagenesis or growth of authigenic carbonates in the sediment column, thus challenging models which rely upon a dramatically changing redox state of the Ediacaran oceans. Here we present 257 δ 44 / 40 Ca and 131 δ26 Mg measurements, along with [Mg], [Mn] and [Sr] data, from carbonates of the Ediacaran-aged Wonoka Formation (Fm.) of South Australia to bring new isotope systems to bear on understanding the 'Shuram' excursion. Data from four measured sections spanning the basin reveal stratigraphically coherent trends, with variability of ∼1.5‰ in δ26 Mg and ∼1.2‰ in δ 44 / 40 Ca. This Ca isotope variability dwarfs the 0.2-0.3 ‰ change seen coeval with the Permian-Triassic mass extinction, the largest recorded in the rock record, and is on par with putative changes in the δ 44 / 40 Ca value of seawater seen over the Phanerozoic Eon. Changes in both isotopic systems are too large to explain with changes in the isotopic composition of Ca and Mg in global seawater given modern budgets and residence times, and thus must be products of alternative processes. Relationships between δ 44 / 40 Ca and [Sr] and δ26 Mg and [Mg] are consistent with mineralogical control (e.g., aragonite vs. calcite, limestone vs. dolostone) on calcium and magnesium isotope variability. The most pristine samples in the Wonoka dataset, preserving Sr concentrations (in the 1000s of ppm range) and δ 44 / 40

  18. Metabolic Flux Elucidation for Large-Scale Models Using 13C Labeled Isotopes

    PubMed Central

    Suthers, Patrick F.; Burgard, Anthony P.; Dasika, Madhukar S.; Nowroozi, Farnaz; Van Dien, Stephen; Keasling, Jay D.; Maranas, Costas D.

    2007-01-01

    A key consideration in metabolic engineering is the determination of fluxes of the metabolites within the cell. This determination provides an unambiguous description of metabolism before and/or after engineering interventions. Here, we present a computational framework that combines a constraint-based modeling framework with isotopic label tracing on a large-scale. When cells are fed a growth substrate with certain carbon positions labeled with 13C, the distribution of this label in the intracellular metabolites can be calculated based on the known biochemistry of the participating pathways. Most labeling studies focus on skeletal representations of central metabolism and ignore many flux routes that could contribute to the observed isotopic labeling patterns. In contrast, our approach investigates the importance of carrying out isotopic labeling studies using a more comprehensive reaction network consisting of 350 fluxes and 184 metabolites in Escherichia coli including global metabolite balances on cofactors such as ATP, NADH, and NADPH. The proposed procedure is demonstrated on an E. coli strain engineered to produce amorphadiene, a precursor to the anti-malarial drug artemisinin. The cells were grown in continuous culture on glucose containing 20% [U-13C]glucose; the measurements are made using GC-MS performed on 13 amino acids extracted from the cells. We identify flux distributions for which the calculated labeling patterns agree well with the measurements alluding to the accuracy of the network reconstruction. Furthermore, we explore the robustness of the flux calculations to variability in the experimental MS measurements, as well as highlight the key experimental measurements necessary for flux determination. Finally, we discuss the effect of reducing the model, as well as shed light onto the customization of the developed computational framework to other systems. PMID:17632026

  19. Nicotine, acetanilide and urea multi-level 2H-, 13C- and 15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry.

    PubMed

    Schimmelmann, Arndt; Albertino, Andrea; Sauer, Peter E; Qi, Haiping; Molinie, Roland; Mesnard, François

    2009-11-01

    Accurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the delta values of these reference materials should bracket the isotopic range of samples with unknown delta values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW-SLAP) and carbonates (NBS 19 and L-SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA-IRMS). At present only L-glutamic acids USGS40 and USGS41 satisfy these requirements for delta13C and delta15N, with the limitation that L-glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i.e. continuous flow) hydrogen reductive gas chromatography-isotope ratio mass-spectrometry (GC-IRMS), (ii) five nicotines for oxidative C, N gas chromatography-combustion-isotope ratio mass-spectrometry (GC-C-IRMS, or GC-IRMS), and (iii) also three acetanilide and three urea reference materials for on-line oxidative EA-IRMS for C and N. Isotopic off-line calibration against international stable isotope measurement standards at Indiana University adhered to the 'principle of identical treatment'. The new reference materials cover the following isotopic ranges: delta2H(nicotine) -162 to -45 per thousand, delta13C(nicotine) -30.05 to +7.72 per thousand, delta15N(nicotine) -6.03 to +33.62 per thousand; delta15N(acetanilide) +1.18 to +40.57 per thousand; delta13C(urea) -34.13 to +11.71 per thousand, delta15N(urea) +0.26 to +40.61 per thousand (recommended delta values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as

  20. Mechanisms linking metabolism of Helicobacter pylori to 18O and 13C-isotopes of human breath CO2

    PubMed Central

    Som, Suman; De, Anulekha; Banik, Gourab Dutta; Maity, Abhijit; Ghosh, Chiranjit; Pal, Mithun; Daschakraborty, Sunil B.; Chaudhuri, Sujit; Jana, Subhra; Pradhan, Manik

    2015-01-01

    The gastric pathogen Helicobacter pylori utilize glucose during metabolism, but the underlying mechanisms linking to oxygen-18 (18O) and carbon-13 (13C)-isotopic fractionations of breath CO2 during glucose metabolism are poorly understood. Using the excretion dynamics of 18O/16O and 13C/12C-isotope ratios of breath CO2, we found that individuals with Helicobacter pylori infections exhibited significantly higher isotopic enrichments of 18O in breath CO2 during the 2h-glucose metabolism regardless of the isotopic nature of the substrate, while no significant enrichments of 18O in breath CO2 were manifested in individuals without the infections. In contrast, the 13C-isotopic enrichments of breath CO2 were significantly higher in individuals with Helicobacter pylori compared to individuals without infections in response to 13C-enriched glucose uptake, whereas a distinguishable change of breath 13C/12C-isotope ratios was also evident when Helicobacter pylori utilize natural glucose. Moreover, monitoring the 18O and 13C-isotopic exchange in breath CO2 successfully diagnosed the eradications of Helicobacter pylori infections following a standard therapy. Our findings suggest that breath 12C18O16O and 13C16O16O can be used as potential molecular biomarkers to distinctively track the pathogenesis of Helicobacter pylori and also for eradication purposes and thus may open new perspectives into the pathogen’s physiology along with isotope-specific non-invasive diagnosis of the infection. PMID:26039789

  1. Stable Water Use Efficiency of Tibetan Alpine Meadows in Past Half Century: Evidence from Wool δ13C Values

    PubMed Central

    Yang, Hao; He, Nianpeng; He, Yongtao; Li, Shenggong; Shi, Peili; Zhang, Xianzhou

    2015-01-01

    Understanding the influences of climatic changes on water use efficiency (WUE) of Tibetan alpine meadows is important for predicting their long-term net primary productivity (NPP) because they are considered very sensitive to climate change. Here, we collected wool materials produced from 1962 to 2010 and investigated the long-term WUE of an alpine meadow in Tibet on basis of the carbon isotope values of vegetation (δ13Cveg). The values of δ13Cveg decreased by 1.34‰ during 1962–2010, similar to changes in δ13C values of atmospheric CO2. Carbon isotope discrimination was highly variable and no trend was apparent in the past half century. Intrinsic water use efficiency (Wi) increased by 18 μmol·mol–1 (approximately 23.5%) during 1962–2010 because the increase in the intercellular CO2 concentration (46 μmol·mol–1) was less than that in the atmospheric CO2 concentration (Ca, 73 μmol·mol–1). In addition, Wi increased significantly with increasing growing season temperature and Ca. However, effective water use efficiency (We) remained relatively stable, because of increasing vapor pressure deficit. Ca, precipitation, and growing season temperature collectively explained 45% of the variation of We. Our findings indicate that the We of alpine meadows in the Tibetan Plateau remained relatively stable by physiological adjustment to elevated Ca and growing season temperature. These findings improve our understanding and the capacity to predict NPP of these ecosystems under global change scenarios. PMID:26660306

  2. Determination of the fractions of syntrophically oxidized acetate in a mesophilic methanogenic reactor through an (12)C and (13)C isotope-based kinetic model.

    PubMed

    Gehring, Tito; Niedermayr, Andrea; Berzio, Stephan; Immenhauser, Adrian; Wichern, Marc; Lübken, Manfred

    2016-10-01

    In order to accurately describe the carbon flow in anaerobic digestion processes, this work investigates the acetate degradation pathways through the use of stable carbon isotope analysis and a mathematical model. Batch assays using labeled (13)C acetate were employed to distinguish the acetate consumption through methanogenic Archaea and acetate-oxidizing Bacteria. Suspended and sessile biomass, with over 400 days of retention time, from a mesophilic (36.5 °C) upflow anaerobic filter was used as inocula in these assays. A three-process model for acetoclastic methanogenesis and syntrophic acetate oxidation (SAO) was developed to allow for a precise quantification of the SAO contribution. The model distinguishes carbon atoms in light and heavy isotopes, (12)C and (13)C, respectively, which permitted the simulation of the isotope ratios variation in addition to gas production, gas composition and acetate concentrations. The model indicated oxidized fractions of acetate between 7 and 18%. Due to the low free ammonia inhibition potential for the acetoclastic methanogens in these assays these findings point to the biomass retention times as a driven factor for the SAO pathway. The isotope-based kinetic model developed here also describes the δ(13)C variations in unlabeled assays accurately and has the potential to determine biological (13)C fractionation factors. PMID:27390036

  3. Stable light isotope biogeochemistry of hydrothermal systems

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.

    1996-01-01

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

  4. Stable light isotope biogeochemistry of hydrothermal systems.

    PubMed

    Des Marais, D J

    1996-01-01

    The stable isotopic composition of the elements O, H, S and C in minerals and other chemical species can indicate the existence, extent, conditions and the processes (including biological activity) of hydrothermal systems. Hydrothermal alteration of the 18O/16O and D/H values of minerals can be used to detect fossil systems and delineate their areal extent. Water-rock interactions create isotopic signatures which indicate fluid composition, temperature, water-rock ratios, etc. The 18O/16O values of silica and carbonate deposits tend to increase with declining temperature and thus help to map thermal gradients. Measurements of D/H values can help to decipher the origin(s) of hydrothermal fluids. The 34S/32S and 13C/12C values of fluids and minerals reflect the origin of the S and C as well as oxygen fugacities and key redox processes. For example, a wide range of 34S/32S values which are consistent with equilibration below 100 degrees C between sulfide and sulfate can be attributed to sulfur metabolizing bacteria. Depending on its magnitude, the difference in the 13C/12C value of CO2 and carbonates versus organic carbon might be attributed either to equilibrium at hydrothermal temperatures or, if the difference exceeds 1% (10/1000), to organic biosynthesis. Along the thermal gradients of thermal spring outflows, the 13C/12C value of carbonates and 13C-depleted microbial organic carbon increases, principally due to the outgassing of relatively 13C-depleted CO2. PMID:9243011

  5. Isotopically nonstationary 13C flux analysis of Myc-induced metabolic reprogramming in B-cells

    PubMed Central

    Murphy, Taylor A.; Dang, Chi V.; Young, Jamey D.

    2012-01-01

    We assessed several methods of 13C metabolic flux analysis (MFA) and found that isotopically nonstationary MFA achieved maximum flux resolution in cultured P493-6 B-cells, which have been engineered to provide tunable expression of the Myc oncoprotein. Comparison of metabolic flux maps obtained under oncogenic (High) and endogenous (Low) Myc expression levels revealed network-wide reprogramming in response to ectopic Myc expression. High Myc cells relied more heavily on mitochondrial oxidative metabolism than Low Myc cells and globally upregulated their consumption of amino acids relative to glucose. TCA cycle and amphibolic mitochondrial pathways exhibited 2- to 4-fold flux increases in High Myc cells, in contrast to modest increases in glucose uptake and lactate excretion. Because our MFA approach relied exclusively upon isotopic measurements of protein-bound amino acids and RNA-bound ribose, it is readily applicable to more complex tumor models that are not amenable to direct extraction and isotopic analysis of free intracellular metabolites. PMID:22898717

  6. Evolution of E. coli on [U-13C]Glucose Reveals a Negligible Isotopic Influence on Metabolism and Physiology

    PubMed Central

    Sandberg, Troy E.; Long, Christopher P.; Gonzalez, Jacqueline E.; Feist, Adam M.; Antoniewicz, Maciek R.; Palsson, Bernhard O.

    2016-01-01

    13C-Metabolic flux analysis (13C-MFA) traditionally assumes that kinetic isotope effects from isotopically labeled compounds do not appreciably alter cellular growth or metabolism, despite indications that some biochemical reactions can be non-negligibly impacted. Here, populations of Escherichia coli were adaptively evolved for ~1000 generations on uniformly labeled 13C-glucose, a commonly used isotope for 13C-MFA. Phenotypic characterization of these evolved strains revealed ~40% increases in growth rate, with no significant difference in fitness when grown on either labeled (13C) or unlabeled (12C) glucose. The evolved strains displayed decreased biomass yields, increased glucose and oxygen uptake, and increased acetate production, mimicking what is observed after adaptive evolution on unlabeled glucose. Furthermore, full genome re-sequencing revealed that the key genetic changes underlying these phenotypic alterations were essentially the same as those acquired during adaptive evolution on unlabeled glucose. Additionally, glucose competition experiments demonstrated that the wild-type exhibits no isotopic preference for unlabeled glucose, and the evolved strains have no preference for labeled glucose. Overall, the results of this study indicate that there are no significant differences between 12C and 13C-glucose as a carbon source for E. coli growth. PMID:26964043

  7. Physiological and isotopic (delta(13)C and delta(18)O) responses of three tropical tree species to water and nutrient availability.

    PubMed

    Cernusak, Lucas A; Winter, Klaus; Turner, Benjamin L

    2009-10-01

    Water-use efficiency and stable isotope composition were studied in three tropical tree species. Seedlings of Tectona grandis, Swietenia macrophylla and Platymiscium pinnatum were grown at either high or low water supply, and with or without added fertilizer. These three species previously exhibited low, intermediate and high whole-plant water-use efficiency (TE) when grown at high water supply in unfertilized soil. Responses of TE to water and nutrient availability varied among species. The TE was calculated as experiment-long dry matter production divided by cumulative water use. Species-specific offsets were observed in relationships between TE and whole-plant (13)C discrimination (Delta(13)C(p)). These offsets could be attributed to a breakdown in the relationship between Delta(13)C(p) and the ratio of intercellular to ambient CO(2) partial pressures (c(i)/c(a)) in P. pinnatum, and to variation among species in the leaf-to-air vapour pressure difference (v). Thus, a plot of v.TE against c(i)/c(a) showed a general relationship among species. Relationships between delta(18)O of stem dry matter and stomatal conductance ranged from strongly negative for S. macrophylla to no relationship for T. grandis. Results suggest inter-specific variation among tropical tree species in relationships between stable isotope ratios (delta(13)C and delta(18)O) and the gas exchange processes thought to affect them. PMID:19558409

  8. Capillary Absorption Spectrometer for 13C Isotopic Composition of Pico to Subpico Molar Sample Quantities

    NASA Astrophysics Data System (ADS)

    Moran, J.; Kelly, J.; Sams, R.; Newburn, M.; Kreuzer, H.; Alexander, M.

    2011-12-01

    Quick incorporation of IR spectroscopy based isotope measurements into cutting edge research in biogeochemical cycling attests to the advantages of a spectroscopy versus mass spectrometry method for making some 13C measurements. The simple principles of optical spectroscopy allow field portability and provide a more robust general platform for isotope measurements. We present results with a new capillary absorption spectrometer (CAS) with the capability of reducing the sample size required for high precision isotopic measurements to the picomolar level and potentially the sub-picomolar level. This work was motivated by the minute sample size requirements for laser ablation isotopic studies of carbon cycling in microbial communities but has potential to be a valuable tool in other areas of biological and geological research. The CAS instrument utilizes a capillary waveguide as a sample chamber for interrogating CO2 via near IR laser absorption spectroscopy. The capillary's small volume (~ 0.5 mL) combined with propagation and interaction of the laser mode with the entire sample reduces sample size requirements to a fraction of that accessible with commercially available IR absorption including those with multi-pass or ring-down cavity systems. Using a continuous quantum cascade laser system to probe nearly adjacent rovibrational transitions of different isotopologues of CO2 near 2307 cm-1 permits sample measurement at low analyte pressures (as low as 2 Torr) for further sensitivity improvement. A novel method to reduce cw-fringing noise in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level after averaging 1,000 scans in 10 seconds. Detection limits down to the 20 picomoles have been observed, a concentration of approximately 400 ppm at 2 Torr in the waveguide with precision and accuracy at or better than 1 %. Improvements in detection and signal averaging electronics and laser power and mode quality are

  9. High-precision position-specific isotope analysis of 13C/12C in leucine and methionine analogues.

    PubMed

    Sacks, Gavin L; Brenna, J Thomas

    2003-10-15

    We report an automated method for high-precision position-specific isotope analysis (PSIA) of carbon in amino acid analogues. Carbon isotope ratios are measured for gas-phase pyrolysis fragments from multiple sources of 3-methylthiopropylamine (3MTP) and isoamylamine (IAA), the decarboxylated analogues of methionine and leucine, using a home-built gas chromatography (GC)-pyrolysis-GC preparation system coupled to a combustion-isotope ratio mass spectrometry system. Over a temperature range of 620-900 degrees C, the characteristic pyrolysis products for 3MTP were CH4, C2H6, HCN, and CH3CN and for IAA products were propylene, isobutylene, HCN, and CH3CN. Fragment origin was confirmed by 13C-labeling, and fragments used for isotope analysis were generated from unique moieties with > 95% structural fidelity. Isotope ratios for the fragments were determined with an average precision of SD(delta13C) < 0.3% per thousand, and relative isotope ratios of fragments from different sources were determined with an average precision of SD(delta(delta)13C) < 0.5% per thousand. Delta(delta)13C values of fragments were invariant over a range of pyrolysis temperatures. The delta(delta)13C of complementary fragments in IAA was within 0.8% per thousand of the delta(delta)13C of the parent compounds, indicating that pyrolysis-induced isotopic fractionation is effectively taken into account with this calibration procedure. Using delta(delta)13C values of fragments, delta(delta)13C values were determined for all four carbon positions of 3MTP and for C1, C2, and the propyl moiety of IAA, either directly or indirectly by mass balance. Large variations in position-specific isotope ratios were observed in samples from different commercial sources. Most dramatically, two 3MTP sources differed by 16.30% per thousand at C1, 48.33% per thousand at C2, 0.37% per thousand at C3, and 5.36% per thousand at C(methyl). These PSIA techniques are suitable for studying subtle changes in intramolecular

  10. Coral skeletal carbon isotopes13C and Δ14C) record the delivery of terrestrial carbon to the coastal waters of Puerto Rico

    USGS Publications Warehouse

    Moyer, R.P.; Grottoli, A.G.

    2011-01-01

    Tropical small mountainous rivers deliver a poorly quantified, but potentially significant, amount of carbon to the world's oceans. However, few historical records of land-ocean carbon transfer exist for any region on Earth. Corals have the potential to provide such records, because they draw on dissolved inorganic carbon (DIC) for calcification. In temperate systems, the stable- (δ13C) and radiocarbon (Δ14C) isotopes of coastal DIC are influenced by the δ13C and Δ14C of the DIC transported from adjacent rivers. A similar pattern should exist in tropical coastal DIC and hence coral skeletons. Here, δ13C and Δ14C measurements were made in a 56-year-old Montastraea faveolata coral growing ~1 km from the mouth of the Rio Fajardo in eastern Puerto Rico. Additionally, the δ13C and Δ14C values of the DIC of the Rio Fajardo and its adjacent coastal waters were measured during two wet and dry seasons. Three major findings were observed: (1) synchronous depletions of both δ13C and Δ14C in the coral skeleton are annually coherent with the timing of peak river discharge, (2) riverine DIC was always more depleted in δ13C and Δ14C than seawater DIC, and (3) the correlation of δ13C and Δ14C was the same in both coral skeleton and the DIC of the river and coastal waters. These results indicate that coral skeletal δ13C and Δ14C are recording the delivery of riverine DIC to the coastal ocean. Thus, coral records could be used to develop proxies of historical land-ocean carbon flux for many tropical regions. Such information could be invaluable for understanding the role of tropical land-ocean carbon flux in the context of land-use change and global climate change.

  11. Coral skeletal carbon isotopes13C and Δ14C) record the delivery of terrestrial carbon to the coastal waters of Puerto Rico

    USGS Publications Warehouse

    Moyer, R.P.; Grottoli, A.G.

    2011-01-01

    Tropical small mountainous rivers deliver a poorly quantified, but potentially significant, amount of carbon to the world's oceans. However, few historical records of land-ocean carbon transfer exist for any region on Earth. Corals have the potential to provide such records, because they draw on dissolved inorganic carbon (DIC) for calcification. In temperate systems, the stable- (??13C) and radiocarbon (??14C) isotopes of coastal DIC are influenced by the ??13C and ??14C of the DIC transported from adjacent rivers. A similar pattern should exist in tropical coastal DIC and hence coral skeletons. Here, ??13C and ??14C measurements were made in a 56-year-old Montastraea faveolata coral growing ~1 km from the mouth of the Rio Fajardo in eastern Puerto Rico. Additionally, the ??13C and ??14C values of the DIC of the Rio Fajardo and its adjacent coastal waters were measured during two wet and dry seasons. Three major findings were observed: (1) synchronous depletions of both ??13C and ??14C in the coral skeleton are annually coherent with the timing of peak river discharge, (2) riverine DIC was always more depleted in ??13C and ??14C than seawater DIC, and (3) the correlation of ??13C and ??14C was the same in both coral skeleton and the DIC of the river and coastal waters. These results indicate that coral skeletal ??13C and ??14C are recording the delivery of riverine DIC to the coastal ocean. Thus, coral records could be used to develop proxies of historical land-ocean carbon flux for many tropical regions. Such information could be invaluable for understanding the role of tropical land-ocean carbon flux in the context of land-use change and global climate change. ?? 2011 United States Geological Survey.

  12. Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

    PubMed Central

    Soong, Jennifer L; Reuss, Dan; Pinney, Colin; Boyack, Ty; Haddix, Michelle L; Stewart, Catherine E; Cotrufo, M. Francesca

    2014-01-01

    Tracing rare stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes and soil organic matter formation to small-scale stable-isotope biomarker probing. Coupling multiple stable isotopes such as 13C with 15N, 18O or 2H has the potential to reveal even more information about complex stoichiometric relationships during biogeochemical transformations. Isotope labeled plant material has been used in various studies of litter decomposition and soil organic matter formation1-4. From these and other studies, however, it has become apparent that structural components of plant material behave differently than metabolic components (i.e. leachable low molecular weight compounds) in terms of microbial utilization and long-term carbon storage5-7. The ability to study structural and metabolic components separately provides a powerful new tool for advancing the forefront of ecosystem biogeochemical studies. Here we describe a method for producing 13C and 15N labeled plant material that is either uniformly labeled throughout the plant or differentially labeled in structural and metabolic plant components. Here, we present the construction and operation of a continuous 13C and 15N labeling chamber that can be modified to meet various research needs. Uniformly labeled plant material is produced by continuous labeling from seedling to harvest, while differential labeling is achieved by removing the growing plants from the chamber weeks prior to harvest. Representative results from growing Andropogon gerardii Kaw demonstrate the system's ability to efficiently label plant material at the targeted levels. Through this method we have produced plant material with a 4.4 atom%13C and 6.7 atom%15N uniform plant label, or material that is differentially labeled by up to 1.29 atom%13C and 0.56 atom%15N in its metabolic and structural components (hot water extractable and hot water residual components

  13. Use of Isotope Ratio Determination (13C/12C) to Assess the Production Method of Sparkling Wine.

    PubMed

    Rossier, Joël S; Maury, Valérie; Gaillard, Laetitia; Pfammatter, Elmar

    2016-01-01

    The production of a sparkling wine can be performed with different methods taking from a few weeks to several years, which often justifies a difference in added value for the consumer. This paper presents the use of isotope ratio δ(13)C measurements combined with physico-chemical analyses for the determination of mislabelling of sparkling wines produced by 'ancestral', 'traditional', 'closed tank' or 'gasification' methods. This work shows that the isotope composition of CO(2) compared with that of the corresponding dried residue of wine (DRW) can assess whether carbonate CO(2) in a sparkling wine originates from alcohol fermentation or from artificial gas addition. Isotopic ratios expressed as δ(13)C(CO2) and δ(13)C(DRW) measurements have been obtained for each wine by gasbench isotopic ratio mass spectroscopy and cavity ring down infrared spectroscopy, respectively. When the difference between δ(13)C(CO2) and δ(13)C(DRW) is negative, the presence of artificial CO(2) can be undoubtedly inferred, which would exclude the production methods 'ancestral' or 'traditional' for instance. Other parameters such as alcohol content, sugar and acid distributions are also important to complete the analytical panel to aid fraud tracking. PMID:27198811

  14. Stable-Isotopic Analysis of Porcine, Bovine, and Ovine Heparins

    PubMed Central

    Jasper, John P.; Zhang, Fuming; Poe, Russell B.; Linhardt, Robert J.

    2014-01-01

    The assessment of provenance of heparin is becoming a major concern for the pharmaceutical industry and its regulatory bodies. Batch-specific [carbon (δ13C), nitrogen (δ15N), oxygen (δ18O), sulfur (δ34S), and hydrogen (δD)] stable-isotopic compositions of five different animal-derived heparins were performed. Measurements readily allowed their differentiation into groups and/or subgroups based on their isotopic provenance. Principle component analysis showed that a bivariate plot of δ13C and δ18O is the best single, bivariate plot that results in the maximum discrimination ability when only two stable isotopes are used to describe the variation in the data set. Stable-isotopic analyses revealed that (i) stable-isotope measurements on these highly-sulfated polysaccharide (MW ~15 kDa) natural products (“biologics”) were feasible; (ii) in bivariate plots, the δ13C versus δ18O plot reveals a well-defined relationship for source differentiation of hogs raised in the US from hogs raised in Europe and China; (iii) the δD versus δ18O plot revealed the most well-defined relationship for source differentiation based on the hydrologic-environmental isotopes of water (D/H and 18O/16O), and (iv) the δ15N versus δ18O and δ34S versus δ18O relationships are both very similar, possibly reflecting the food sources used by the different heparin producers. PMID:25186630

  15. Stable isotopic analysis of porcine, bovine, and ovine heparins.

    PubMed

    Jasper, John P; Zhang, Fuming; Poe, Russell B; Linhardt, Robert J

    2015-02-01

    The assessment of provenance of heparin is becoming a major concern for the pharmaceutical industry and its regulatory bodies. Batch-specific [carbon (δ(13) C), nitrogen (δ(15) N), oxygen (δ(18) O), sulfur (δ(34) S), and hydrogen (δD)] stable isotopic compositions of five different animal-derived heparins were performed. Measurements readily allowed their differentiation into groups and/or subgroups based on their isotopic provenance. Principle component analysis showed that a bivariate plot of δ(13) C and δ(18) O is the best single, bivariate plot that results in the maximum discrimination ability when only two stable isotopes are used to describe the variation in the data set. Stable isotopic analyses revealed that (1) stable isotope measurements on these highly sulfated polysaccharide (molecular weight ∼15 kDa) natural products ("biologics") were feasible; (2) in bivariate plots, the δ(13) C versus δ(18) O plot reveals a well-defined relationship for source differentiation of hogs raised in the United States from hogs raised in Europe and China; (3) the δD versus δ(18) O plot revealed the most well-defined relationship for source differentiation based on the hydrologic environmental isotopes of water (D/H and (18) O/(16) O); and (4) the δ(15) N versus δ(18) O and δ(34) S versus δ(18) O relationships are both very similar, possibly reflecting the food sources used by the different heparin producers. PMID:25186630

  16. Stable Isotope Characterization of TICs/TIMs: Analytical Progress Report

    SciTech Connect

    Volpe, A M; Singleton, M J

    2009-06-05

    We measured twelve alkali cyanide samples that were also sent to ORNL and PNNL collaborators. While results indicate distinct {delta}{sup 13}C and {delta}{sup 15}N values that would be useful to signature studies, the alkali cyanides, especially NaCN, show chemical breakdown during storage that will influence forensic analysis. Carbon and nitrogen stable isotopic compositions of raw materials used to synthesis TETS were measured. Results indicate wide ranges in {delta}{sup 13}C and {delta}{sup 15}N values. Using these raw materials, LLNL scientists synthesized three batches of TETS following published procedures. Stable isotopic measurements of TETS synthesis products indicates nitrogen ({var_epsilon} {sup 15}N = -1.7 to -0.8) and carbon ({var_epsilon} {sup 13}C = -1.0 to -0.1) fractionation during production.

  17. Dissecting the Mechanisms of a Class of Chemical Glycosylation Using Primary 13C Kinetic Isotope Effects

    PubMed Central

    Huang, Min; Garrett, Graham E.; Birlirakis, Nicolas; Bohé, Luis

    2012-01-01

    Although arguably the most important reaction in glycoscience, chemical glycosylations are among the least well understood of organic chemical reactions resulting in an unnecessarily high degree of empiricism and a brake on rational development in this critical area. To address this problem primary 13C kinetic isotope effects now have been determined for the formation of β- and α-manno- and glucopyranosides by a natural abundance NMR method. In contrast to the common current assumption, for three of the four cases studied the experimental values concur with those computed for associative displacement of the intermediate covalent glycosyl trifluoromethanesulfonates. For the formation of the α-mannopyranosides the experimentally determined KIE differs significantly from that computed for an associative displacement, which is strongly suggestive of a dissociative mechanism that approaches the intermediacy of a glycosyl oxocarbenium ion. The application of comparable experiments to other glycosylation systems should shed further light on their glycosylation mechanisms and thus assist in the design of better reactions conditions with improved stereoselectivity. PMID:22824899

  18. Dissecting the mechanisms of a class of chemical glycosylation using primary 13C kinetic isotope effects

    NASA Astrophysics Data System (ADS)

    Huang, Min; Garrett, Graham E.; Birlirakis, Nicolas; Bohé, Luis; Pratt, Derek A.; Crich, David

    2012-08-01

    Although arguably the most important reaction in glycoscience, chemical glycosylations are among the least well understood of organic chemical reactions, resulting in an unnecessarily high degree of empiricism and a brake on rational development in this critical area. To address this problem, primary 13C kinetic isotope effects have now been determined for the formation of β- and α-manno- and glucopyranosides using a natural abundance NMR method. In contrast to the common current assumption, for three of the four cases studied the experimental and computed values are indicative of associative displacement of the intermediate covalent glycosyl trifluoromethanesulfonates. For the formation of the α-mannopyranosides, the experimentally determined KIE differs significantly from that computed for an associative displacement, which is strongly suggestive of a dissociative mechanism that approaches the intermediacy of a glycosyl oxocarbenium ion. The application of analogous experiments to other glycosylation systems should shed further light on their mechanisms and thus assist in the design of better reactions conditions with improved stereoselectivity.

  19. 13C-methacetin breath test: isotope-selective nondispersive infrared spectrometry in comparison to isotope ratio mass spectrometry in volunteers and patients with liver cirrhosis.

    PubMed

    Adamek, R J; Goetze, O; Boedeker, C; Pfaffenbach, B; Luypaerts, A; Geypens, B

    1999-12-01

    The 13C-methacetin breath test (MBT) has been proposed for the noninvasive evaluation of the hepatic mixed function oxidase activity. Up to now, stable isotope analysis of carbon dioxide of the MBT has been carried out with isotope ratio mass spectrometry (IRMS). The aim of the present study was to test a recently developed isotope-selective nondispersive infrared spectrometer (NDIRS) in comparison to IRMS in healthy volunteers and patients with liver cirrhosis. Ten healthy volunteers (range 22 to 76 years) and ten patients with histologically proven liver cirrhosis (range 47 to 71 years; Child Pugh score A = 5, B = 3, C = 2) were studied. After an overnight fast each subject received 2 mg/kg BW of 13C-methacetin dissolved in 100 ml of tea. Breath samples were obtained before substrate administration and after 5, 10, 15, 20, 30, 40, 50, 60, 80, 100, 120, 150, 180 min. The 13C/12C-ratio was analyzed in each breath sample both by NDIRS (IRIS, Wagner Analysen Technik, Worpswede, Germany) and CF-IRMS (ABCA, Europa Scientific, Crewe, UK). Results were expressed as delta over baseline (DOB [/1000]) and as cumulative percentage doses of 13C recovered (cPDR [%]) at each time interval. Correlations between IRMS and NDIRS were tested by linear regression correlation. For measuring agreement an Altman-Bland-plot was performed. Applying correlation analysis a linear correlation was found (DOB: y = 1.068 +/- 0.0012.x + 2.088 +/- 0.2126, r = 0.98, p < 0.0001; cPDR: y = 1.148 +/- 0.0109.x + 0.569 +/- 0.172; r = 0.99, p < 0.0001). For DOB the mean difference (d) was 2.9/1000 and the standard deviation (SD) of the difference was 2.7/1000. The limits of agreement (d +/- SD) were -2.5/1000 and 8.3/1000. The comparison of DOB- and cPDR-values by NDIRS and IRMS shows a high linear correlation. However, the distance of the limits of agreement is wide. Consequently, the validity of the MBT could be influenced which could make MBT by NDIRS unprecise for exact evaluation of hepatocellular

  20. Synthesis of isotopically labeled R- or S-[.sup.13C, .sup.2H] glycerols

    DOEpatents

    Martinez, Rodolfo A.; Unkefer, Clifford J.; Alvarez, Marc A.

    2008-01-22

    The present invention is directed to asymmetric chiral labeled glycerols including at least one chiral atom, from one to two .sup.13C atoms and from zero to four deuterium atoms bonded directly to a carbon atom, e.g., (2S) [1,2-.sup.13C.sub.2]glycerol and (2R) [1,2-.sup.13C.sub.2]glycerol, and to the use of such chiral glycerols in the preparation of labeled amino acids.

  1. Stable Isotope Spectroscopy for Diagnostic Medicine

    NASA Astrophysics Data System (ADS)

    Murnick, D. E.

    2000-06-01

    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.

  2. Does avian malaria infection affect feather stable isotope signatures?

    PubMed

    Yohannes, Elizabeth; Palinauskas, Vaidas; Valkiūnas, Gediminas; Lee, Raymond W; Bolshakov, Casimir V; Bensch, Staffan

    2011-12-01

    It is widely accepted that stable isotope ratios in inert tissues such as feather keratin reflect the dietary isotopic signature at the time of the tissue synthesis. However, some elements such as stable nitrogen isotopes can be affected by individual physiological state and nutritional stress. Using malaria infection experiment protocols, we estimated the possible effect of malaria parasite infections on feather carbon (δ(13)C) and nitrogen (δ(15)N) isotope signatures in juvenile common crossbills Loxia curvirostra. The birds were experimentally infected with Plasmodium relictum (lineage SGS1) and P. ashfordi (GRW2), two widespread parasites of passerines. Experimental birds developed heavy parasitemia of both parasites and maintained high levels throughout the experiment (33 days). We found no significant difference between experimental and control birds in both δ(13)C and δ(15)N values of feathers re-grown. The study shows that even heavy primary infections of malaria parasites do not affect feather δ(13)C and δ(15)N isotopic signatures. The results of this experiment demonstrate that feather isotope values of wild-caught birds accurately reflect the dietary isotopic sources at the time of tissue synthesis even when the animal's immune system might be challenged due to parasitic infection. PMID:21671039

  3. Nicotine, acetanilide and urea multi-level2H-,13C- and15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry

    USGS Publications Warehouse

    Schimmelmann, A.; Albertino, A.; Sauer, P.E.; Qi, H.; Molinie, R.; Mesnard, F.

    2009-01-01

    Accurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the S values of these reference materials should bracket the isotopic range of samples with unknown S values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW-SLAP) and carbonates (NBS 19 and L-SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA-IRMS). At present only L-glutamic acids USGS40 and USGS41 satisfy these requirements for ??13C and ??13N, with the limitation that L-glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i.e. continuous flow) hydrogen reductive gas chromatography-isotope ratio mass-spectrometry (GC-IRMS), (ii) five nicotines for oxidative C, N gas chromatography-combustion-isotope ratio mass-spectrometry (GC-C-IRMS, or GC-IRMS), and (iii) also three acetanilide and three urea reference materials for on-line oxidative EA-IRMS for C and N. Isotopic off-line calibration against international stable isotope measurement standards at Indiana University adhered to the 'principle of identical treatment'. The new reference materials cover the following isotopic ranges: ??2Hnicotine -162 to -45%o, ??13Cnicotine -30.05 to +7.72%, ?? 15Nnicotine -6.03 to +33.62%; ??15N acetanilide +1-18 to +40.57%; ??13Curea -34.13 to +11.71%, ??15Nurea +0.26 to +40.61% (recommended ?? values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as the first organic nitrogen stable isotope reference materials for GC-IRMS that are available with different ??13N

  4. Stable carbon isotopes and the study of prehistoric human diet.

    PubMed

    Boutton, T W; Lynott, M J; Bumsted, M P

    1991-01-01

    Mass spectrometric analysis of the stable carbon isotope composition (13C/12C or delta 13C) of bone collagen from human remains recovered at archaeological sites provides a direct chemical method for investigating dietary patterns of prehistoric human populations. This methodology is based on the facts that (1) different food items within the human diet have distinct delta 13C values, and (2) the delta 13C value of human bone collagen is determined by the delta 13C value of the diet. Studies of the development of subsistence patterns based on corn agriculture, one of the most significant developments in North American prehistory, can benefit from the use of stable carbon isotope techniques because corn has a high delta 13C value relative to other components of the human diet. Measurements of delta 13C of bone collagen from prehistoric human skeletal remains from southeastern Missouri and northeastern Arkansas indicate that intensive corn agriculture began in this region around A.D. 1000, that the incorporation of corn into the human diet was a rapid phenomenon, and that 35 to 77% of the human diet from A.D. 1000 to A.D. 1600 consisted of corn. Results from an isochronous population in southeastern South Dakota (A.D. 1400) suggest that 78 to 90% of the diet of this group consisted of corn, with no difference between males and females. Coupled with more traditional archaeological methods, stable carbon isotope analysis of bone collagen can significantly enhance reconstruction of dietary patterns of prehistoric humans. PMID:1910520

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

    PubMed

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

    2008-10-01

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

  6. Spatially resolved δ13C analysis using laser ablation isotope ratio mass spectrometry

    NASA Astrophysics Data System (ADS)

    Moran, J.; Riha, K. M.; Nims, M. K.; Linley, T. J.; Hess, N. J.; Nico, P. S.

    2014-12-01

    Inherent geochemical, organic matter, and microbial heterogeneity over small spatial scales can complicate studies of carbon dynamics through soils. Stable isotope analysis has a strong history of helping track substrate turnover, delineate rhizosphere activity zones, and identifying transitions in vegetation cover, but most traditional isotope approaches are limited in spatial resolution by a combination of physical separation techniques (manual dissection) and IRMS instrument sensitivity. We coupled laser ablation sampling with isotope measurement via IRMS to enable spatially resolved analysis over solid surfaces. Once a targeted sample region is ablated the resulting particulates are entrained in a helium carrier gas and passed through a combustion reactor where carbon is converted to CO2. Cyrotrapping of the resulting CO2 enables a reduction in carrier gas flow which improves overall measurement sensitivity versus traditional, high flow sample introduction. Currently we are performing sample analysis at 50 μm resolution, require 65 ng C per analysis, and achieve measurement precision consistent with other continuous flow techniques. We will discuss applications of the laser ablation IRMS (LA-IRMS) system to microbial communities and fish ecology studies to demonstrate the merits of this technique and how similar analytical approaches can be transitioned to soil systems. Preliminary efforts at analyzing soil samples will be used to highlight strengths and limitations of the LA-IRMS approach, paying particular attention to sample preparation requirements, spatial resolution, sample analysis time, and the types of questions most conducive to analysis via LA-IRMS.

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

    PubMed

    McCue, Marshall D; Pollock, Erik D

    2008-08-01

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

  8. Stable isotopes determination in some Romanian fruit juices.

    PubMed

    Magdas, Dana Alina; Puscas, Romulus

    2011-09-01

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

  9. Magnetic isotope effects in the photolysis of dibenzyl ketone on porous silica. /sup 13/C and /sup 17/O enrichments

    SciTech Connect

    Turro, N.J.; Cheng, C.C.; Wan, P.; Chung, C.; Mahler, W.

    1985-04-25

    The photolysis of dibenzyl ketone (DBK) on porous silica has been investigated. Both /sup 13/C and /sup 17/O isotopic enrichment in the ketone remaining after partial photolysis is demonstrated. The efficiency of /sup 13/C enrichment was found to be relatively insensitive to the average pore diameter of the silica host, to the percent coverage by DBK, and to the application of an external magnetic field. A significant dependence of /sup 13/C enrichment with temperature, with a maximum in the enrichment-temperature profile, was observed. The results are interpreted in terms of the competition between pathways available to the triplet C/sub 6/H/sub 5/CH/sub 2/COCH/sub 2/C/sub 6/H/sub 5/ radical pair produced by photolysis of DBK.

  10. Bayesian stable isotope mixing models

    EPA Science Inventory

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

  11. Identifying the African Wintering Grounds of Hybrid Flycatchers Using a Multi–Isotope (δ2H, δ13C, δ15N) Assignment Approach

    PubMed Central

    Van Wilgenburg, Steven L.; Hobson, Keith A.; Folmer, Eelke; Font, Laura; Klaassen, Marcel

    2014-01-01

    Migratory routes and wintering grounds can have important fitness consequences, which can lead to divergent selection on populations or taxa differing in their migratory itinerary. Collared (Ficedula albicollis) and pied (F. hypoleuca) flycatchers breeding in Europe and wintering in different sub-Saharan regions have distinct migratory routes on the eastern and western sides of the Sahara desert, respectively. In an earlier paper, we showed that hybrids of the two species did not incur reduced winter survival, which would be expected if their migration strategy had been a mix of the parent species' strategies potentially resulting in an intermediate route crossing the Sahara desert to different wintering grounds. Previously, we compared isotope ratios and found no significant difference in stable-nitrogen isotope ratios (δ15N) in winter-grown feathers between the parental species and hybrids, but stable-carbon isotope ratios (δ13C) in hybrids significantly clustered only with those of pied flycatchers. We followed up on these findings and additionally analyzed the same feathers for stable-hydrogen isotope ratios (δ2H) and conducted spatially explicit multi-isotope assignment analyses. The assignment results overlapped with presumed wintering ranges of the two species, highlighting the efficacy of the method. In contrast to earlier findings, hybrids clustered with both parental species, though most strongly with pied flycatcher. PMID:24847717

  12. Constraining {sup 13}C amounts in AGB stars through isotopic analysis of trace elements in presolar SiC.

    SciTech Connect

    Barzyk, J. G.; Savina, M. R.; Davis, A. M.; Gallino, R.; Gyngard, F.; Amari, S.; Zinner, E.; Pelliln, M. J.; Lewis, R. S.; Clayton, R. N.; Materials Science Division; Univ. Chicago; Chicago Ctr Cosmochem.; Universita di Torino; Washington Univ.

    2007-07-01

    Analyses of the isotopic compositions of multiple elements (Mo, Zr, and Ba) in individual mainstream presolar SiC grains were done by resonant ionization mass spectrometry (RIMS). While most heavy element compositions were consistent with model predictions for the slow neutron capture process (s-process) in low-mass (1.5-3 M{sub {circle_dot}}) asymptotic giant branch stars of solar metallicity when viewed on single-element three-isotope plots, grains with compositions deviating from model predictions were identified on multi-element plots. These grains have compositions that cannot result from any neutron capture process but can be explained by contamination in some elements with solar system material. Previous work in which only one heavy element per grain was examined has been unable to identify contaminated grains. The multi-element analyses of this study detected contaminated grains which were subsequently eliminated from consideration. The uncontaminated grains form a data set with a greatly reduced spread on the three-isotope plots of each element measured, corresponding to a smaller range of {sup 13}C pocket efficiencies in parent AGB stars. Furthermore, due to this reduced spread, the nature of the stellar starting material, previously interpreted as having solar isotopic composition, is uncertain. The constraint on {sup 13}C pocket efficiencies in parent stars of these grains may help uncover the mechanism responsible for formation of {sup 13}C, the primary neutron source for s-process nucleosynthesis in low-mass stars.

  13. Effect of age and ration on diet-tissue isotopic13C, Δ15N) discrimination in striped skunks (Mephitis mephitis).

    PubMed

    Hobson, Keith A; Quirk, Travis W

    2014-01-01

    An important prerequisite for the effective use of stable isotopes in animal ecology is the accurate assessment of isotopic discrimination factors linking animals to their diets for a multitude of tissue types. Surprisingly, these values are poorly known in general and especially for mammalian carnivores and omnivores in particular. Also largely unknown are the factors that influence diet-tissue isotopic discrimination such as nutritional quality and age. We raised adult and juvenile striped skunks (Mephitis mephitis) in captivity on a constant omnivore diet (Mazuri Omnivore A 5635). Adults (n=6) and juveniles (n=3) were kept for 7 months and young (n=7) to the age of 50 days. We then examined individuals for stable carbon (δ(13)C) and nitrogen (δ(15)N) isotope values of hair, nails, lipid, liver, muscle, bone collagen and the plasma, and cellular fractions of blood. Discrimination values differed among age groups and were significantly higher for young compared with their mothers, likely due to the effects of weaning. Δ(15)N isotopic discrimination factors ranged from 3.14 (nails) to 5.6‰ (plasma) in adults and 4.3 (nails) to 5.8‰ (liver) for young. For Δ(13)C, values ranged from-3.3 (fat) to 3.0‰ (collagen) in adults and from-3.3 (fat) to 2.0‰ (collagen) in young. Our data provide an important tool for predicting diets and source of feeding for medium-sized mammalian omnivorous adults integrated over short (e.g. liver, plasma) through long (e.g. collagen) periods and underline the potential effects of age on isotopic values in omnivore diets. PMID:24506487

  14. Lower to middle Miocene isotope ( sup 87 Sr/ sup 86 Sr,. delta. sup 18 O,. delta. sup 13 C) standard sections, DSDP site 608

    SciTech Connect

    Miller, K.G.; Feigenson, M.D. ); Wright, J.D. )

    1990-05-01

    Isotopes changes ({sup 87}Sr/{sup 86}Sr, {delta}{sup 18}O, {delta}{sup 13}C) have been correlated to the geologic time scale primarily by biostratigraphy. Biostratigraphic correlations suffer from problems of diachrony and taxonomy. Magnetostratigraphy provides a facies-independent correlation tool, but there are few Tertiary sections with unambiguous magnetostratigraphy. The authors previously developed an isotope standard for the Oligocene at the only location with a pristine magnetochronology, Site 522. They extend this approach to Site 608 in the northeastern North Atlantic, which contains a relatively straightforward Miocene magnetochronology. They establish Miocene oxygen isotope Chronozones MI1 through MI6 at Sites 522 and 608, which are directly tied to the geomagnetic polarity time scale (GPTS). The integration of stable isotopes, Sr isotopes, biostratigraphy, and magnetostratigraphy at site 608 provides a standard section with which other Sr isotope and oxygen isotope records can be correlated. For example, using oxygen isotopes to correlate, the Sr isotope record from Site 608 compares well with previously published records from Sites 516 and 590. The firm ties of the Oligocene to middle Miocene isotope records with the GPTS allows them to establish the nature of the change in Sr isotopes between 38 and 8 Ma. There were moderately high rates of {sup 87}Sr/{sup 86}Sr change during the Oligocene ({approximately}0.000030/m.y.), yielding stratigraphic resolution of {plus minus}1.0 m.y. The rate of change of {sup 87}Sr/{sup 86}Sr increased during the early Miocene. They estimate that the rate of change between 23 and 15 Ma was greater than 0.000060/m.y. Given their ability to reproduce Sr isotope measurements ({plus minus}0.000020 to {plus minus}0.000030), temporal resolution is better than {plus minus}0.5 my. for the early to early middle Oliocene.

  15. What is the main food source of the shipworm (Teredo navalis)? A stable isotope approach

    NASA Astrophysics Data System (ADS)

    Paalvast, Peter; van der Velde, Gerard

    2013-07-01

    Stable isotope analysis of soft bodies of the shipworm Teredo navalis demonstrated that this species is mainly feeding on seston by filter feeding in contrast to wood consumption. T. navalis showed similar stable isotope values (δ13C, δ15N) as Mytilus edulis and Crassostrea gigas, which species were attached to the wood instead of boring into.

  16. Using Bayesian Stable Isotope Mixing Models to Enhance Marine Ecosystem Models

    EPA Science Inventory

    The use of stable isotopes in food web studies has proven to be a valuable tool for ecologists. We investigated the use of Bayesian stable isotope mixing models as constraints for an ecosystem model of a temperate seagrass system on the Atlantic coast of France. δ13C and δ15N i...

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

    EPA Science Inventory

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

  18. Stable Carbon Isotope Record in a Palau Sclerosponge

    NASA Astrophysics Data System (ADS)

    Grottoli, A. G.

    2002-12-01

    The ratio of stable carbon isotopes13C) deposited in the calcium carbonate skeleton of marine sclerosponges appears to record the carbon isotopic composition of seawater mixed-layer dissolved inorganic carbon (δ13CDIC). Thus the δ13C signature chronicled in sclerosponge skeletons offers a promising multi-century proxy record of seawater mixed-layer δ13CDIC throughout the tropics. Here, a high-resolution (0.1 mm) δ13C record for a 7.7 cm Acanthocheatetes wellsi sclerosponge from Palau (7N, 134W) is presented. At a published growth rate of 0.45 mm per year, this record spans ~s170 years beginning in July 2001 and going back to 1831. The δ13C values for a definitive 10-year A. wellsi record spanning 1989-1998 were similar to δ13C values here for the first 4.7 mm of the record providing supporting evidence for the growth rate. The sclerosponge δ13C shows a distinct Seuss Effect. At the time this abstract was submitted, the analysis of the first 16 mm of the sclerosponge revealed a significant decrease in δ13C with time [δ13C = 0.02 (distance) + 2.64, r2 = 0.73, p < 0.0001, where time is marked by distance in millimeters from the growing edge] corresponding to a decrease in δ13C of 0.076‰ per decade. For comparison, published low-frequency measurements in Australian, New Caledonian and Jamaican sclerosponges have yielded decreases in δ13C of ~s0.05 to 0.08 ‰ per decade over the past 40 years. Preliminary interpretation of the data indicates that the amount of atmospheric CO2 contributing to the seawater δ13CDIC at Palau is intermediate to Australia and Jamaica. In addition, visual examination of the δ13C record reveals regular fluctuation in δ13C that may correspond to annual variability in δ13CDIC. This research presents the first century or longer sclerosponge δ13C record from the northwester equatorial Pacific.

  19. Stable isotope patterns in micronekton from the Mozambique Channel

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    We measured the stable carbon (δ13C) and nitrogen (δ15N) isotopic composition of tissues of micronektonic organisms (fishes, squids, crustaceans and gelatinous organisms) collected in the Mozambique Channel during two scientific cruises in 2008 and 2009. The oceanic circulation in the Mozambique Channel is dominated by mesoscale cyclonic and anticyclonic eddies which play a key role in biological processes of less-productive deep-sea ecosystems. We investigated the potential impact of mesoscale features on the δ13C and δ15N values of 32 taxa of micronekton. Fishes, squids, crustaceans and gelatinous organisms encompassed a wide range of isotopic niches, with large overlaps among species. Our results showed that mesoscale features did not really influence the isotopic signatures of the sampled organisms, although cyclonic eddies can occasionally impact the nitrogen signatures of micronekton. We show that δ13C values were intermediate between standard offshore and nearshore signatures, suggesting that pelagic production in the Mozambique Channel could be partly supported by the transport and export of inorganic and organic particles from the Mozambican coast toward the offshore area. Trophic levels calculated from δ15N values ranged from 2.6 to 4.2, showing that micronekton taxa can be tertiary consumers in the Mozambique Channel. Our findings evidenced clusters of micronektonic organisms according to their δ15N or δ13C isotopic signatures, but variations in stable isotope values reflect a complex set of embedded processes linked to physical mesoscale dynamics (rotational dynamics of eddies) and basic biology and ecology of micronektonic organisms (vertical habitat, migration pattern, dietary habits, body length) that are discussed with regard to the stable isotope method based on time-integrated assimilated food.

  20. The use of stable isotopes for food web analysis.

    PubMed

    Wada, E; Mizutani, H; Minagawa, M

    1991-01-01

    General aspects in isotope biogeochemistry was summarized with emphasis on delta 15N and delta 13C contents in plants and animals in natural ecosystems. In the estuary, the variation of isotope ratios were principally governed by the mixing of land-derived organic matter, marine phytoplankton, and seagrasses. A clear cut linear relationship between animal delta 15N and its trophic level was obtained in the Antarctic food chain system. Several current efforts to use the stable isotopes for food web analysis were demonstrated for some terrestrial and marine systems as well as human food web. PMID:1910519

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

    PubMed

    Brand, Willi A; Coplen, Tyler B

    2012-09-01

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

  2. Stable isotope deltas: Tiny, yet robust signatures in nature

    USGS Publications Warehouse

    Brand, Willi A.; Coplen, Tyler B.

    2012-01-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including 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

  3. Lipid Extraction and the Fugacity of Stable Isotope Values

    NASA Astrophysics Data System (ADS)

    Padula, V.; Causey, D.; Wolf, N.; Welker, J. M.

    2013-12-01

    Stable isotope analysis of blood, feathers, and other tissues are often used to infer migration patterns, diet composition and trophic status of seabirds. Tissues contain variable amounts of lipids that are depleted in the heavy carbon isotope (13C) and may introduce a bias in these values. There is evidence that lipid extraction may affect other stable isotope ratios, such as δ15N. Consequently, correction factors need to be applied to appropriately interpret δ13C and δ15N values for individual species and tissue type. In this study, we collected seven species of seabirds from the Near Islands, the western most group of islands in the Aleutian Island archipelago. We sampled kidney, liver, heart and muscle samples from each bird and after freeze drying, individual tissue samples were divided into two subsamples. We left one subsample unaltered and extracted lipids from the other subsample using a 2:1 chloroform-methanol solution. We found that the change in δ13C values after lipid extraction (Δδ13C) varied widely among categories (eg., species, tissue type) from 0 - 4 ‰, while Δδ15N values ranged from 0 to 2‰. Notably, within category variation was nonsignificant and the Δδ values were linear against the covariant C:N ratio of the isotopic data, which allows us to use arithmetic corrections for categorical values. Our data strongly indicate that the effects of lipid extraction on stable isotopic values, while linear within category, vary widely by species, tissue, geographic area, year of collection, and isotope. Fugacity is usually employed as a thermodynamic quantity related to the chemical potential or activity that characterizes the escaping tendency from a phase (eg. Mackay & Paterson 1982). Here we use fugacity in the earlier, broader sense of fleeting, transitory, or instable states (eg., S. Johnson 1751), and its measure may be approximated by the higher order variance of Δδ13C and Δδ15N among data categories. Clearly, understanding the

  4. Stable Isotope Database: present and past archives

    NASA Astrophysics Data System (ADS)

    Bolliet, Timothé

    2014-05-01

    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.

  5. Insight on RDX degradation mechanism by Rhodococcus strains using 13C and 15N kinetic isotope effects.

    PubMed

    Bernstein, Anat; Ronen, Zeev; Gelman, Faina

    2013-01-01

    The explosive Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is known to be degraded aerobically by various isolates of the Rhodococcus species, with denitration being the key step, mediated by Cytochrome P450. Our study aimed at gaining insight into the RDX degradation mechanism by Rhodococcus species and comparing isotope effects associated with RDX degradation by distinct Rhodococcus strains. For these purposes, enrichment in (13)C and (15)N isotopes throughout RDX denitration was studied for three distinct Rhodococcus strains, isolated from soil and groundwater in an RDX-contaminated site. The observable (15)N enrichment throughout the reaction, together with minor (13)C enrichment, suggests that N-N bond cleavage is likely to be the key rate-limiting step in the reaction. The similarity in the kinetic (15)N isotope effect between the three tested strains suggests that either isotope-masking effects are negligible, or are of a similar extent for all tested strains. The lack of variability in the kinetic (15)N isotope effect allows the interpretation of environmental studies with greater confidence. PMID:23215036

  6. 12C/ 13C kinetic isotope effects of the gas-phase reactions of isoprene, methacrolein, and methyl vinyl ketone with OH radicals

    NASA Astrophysics Data System (ADS)

    Iannone, Richard; Koppmann, Ralf; Rudolph, Jochen

    The stable-carbon kinetic isotope effects (KIEs) for the gas-phase reactions of isoprene, methacrolein (MACR), and methyl vinyl ketone (MVK) with OH radicals were studied in a 25 L reaction chamber at (298 ± 2) K and ambient pressure. The time dependence of both the stable-carbon isotope ratios and the concentrations was determined using a gas-chromatography combustion isotope ratio mass spectrometry (GCC-IRMS) system. The volatile organic compounds (VOCs) used in the KIE experiments had natural-abundance isotopic composition thus KIE data obtained from these experiments can be directly applied to atmospheric studies of isoprene chemistry. All 12C/ 13/C KIE values are reported as ɛ values, where ɛ = (KIE - 1) × 1000‰, and KIE = k12/ k13. The following average stable-carbon KIEs were obtained: (6.56 ± 0.12)‰ (isoprene), (6.47 ± 0.27)‰ (MACR), and (7.58 ± 0.47)‰ (MVK). The measured KIEs all agree within uncertainty to an inverse molecular mass (MM) dependence of OHɛ(‰) = (487 ± 18)MM -1, which was derived from two previous studies [ J. Geophys. Res.2000, 105, 29329-29346; J. Phys. Chem. A2004, 108, 11537-11544]. Upon adding the isoprene, MACR, and MVK OHɛ values from this study, the inverse MM dependence changes only marginally to OHɛ(‰) = (485 ± 14)MM -1. The addition of these isoprene OHɛ values to a recently measured set of ɛO3 values in an analogous study [ Atmos. Environ.2008, 42, 8728-8737] allows for estimates of the average change in the 12C/ 13C ratio due to processing in the troposphere.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  9. Enhanced forensic discrimination of pollutants by position-specific isotope analysis using isotope ratio monitoring by (13)C nuclear magnetic resonance spectrometry.

    PubMed

    Julien, Maxime; Nun, Pierrick; Höhener, Patrick; Parinet, Julien; Robins, Richard J; Remaud, Gérald S

    2016-01-15

    In forensic environmental investigations the main issue concerns the inference of the original source of the pollutant for determining the liable party. Isotope measurements in geochemistry, combined with complimentary techniques for contaminant identification, have contributed significantly to source determination at polluted sites. In this work we have determined the intramolecular (13)C profiles of several molecules well-known as pollutants. By giving additional analytical parameters, position-specific isotope analysis performed by isotope ratio monitoring by (13)C nuclear magnetic resonance (irm-(13)C NMR) spectrometry gives new information to help in answering the major question: what is the origin of the detected contaminant? We have shown that isotope profiling of the core of a molecule reveals both the raw materials and the process used in its manufacture. It also can reveal processes occurring between the contamination site 'source' and the sampling site. Thus, irm-(13)C NMR is shown to be a very good complement to compound-specific isotope analysis currently performed by mass spectrometry for assessing polluted sites involving substantial spills of pollutant. PMID:26592622

  10. 13C-isotope analyses reveal that chemolithoautotrophic Gamma- and Epsilonproteobacteria feed a microbial food web in a pelagic redoxcline of the central Baltic Sea.

    PubMed

    Glaubitz, Sabine; Lueders, Tillmann; Abraham, Wolf-Rainer; Jost, Günter; Jürgens, Klaus; Labrenz, Matthias

    2009-02-01

    Marine pelagic redoxclines are zones of high dark CO(2) fixation rates, which can correspond up to 30% of the surface primary production. However, despite this significant contribution to the pelagic carbon cycle, the identity of most chemolithoautotrophic organisms is still unknown. Therefore, the aim of this study was to directly link the dark CO(2) fixation capacity of a pelagic redoxcline in the central Baltic Sea (Landsort Deep) with the identity of the main chemolithoautotrophs involved. Our approach was based on the analysis of natural carbon isotope signatures in fatty acid methyl esters (FAMEs) and on measurements of CO(2) incorporation in (13)C-bicarbonate pulse experiments. The incorporation of (13)C into chemolithoautotrophic cells was investigated by rRNA-based stable isotope probing (RNA-SIP) and FAME analysis after incubation for 24 and 72 h under in situ conditions. Our results demonstrated that fatty acids indicative of Proteobacteria were significantly enriched in (13)C slightly below the chemocline. RNA-SIP analyses revealed that two different Gammaproteobacteria and three closely related Epsilonproteobacteria of the Sulfurimonas cluster were active dark CO(2)-fixing microorganisms, with a time-dependent community shift between these groups. Labelling of Archaea was not detectable, but after 72 h of incubation the (13)C-label had been transferred to a potentially bacterivorous ciliate related to Euplotes sp. Thus, RNA-SIP provided direct evidence for the contribution of chemolithoautotrophic production to the microbial food web in this marine pelagic redoxcline, emphasizing the importance of dark CO(2)-fixing Proteobacteria within this habitat. PMID:18793316

  11. Biogeochemical Indicators in High- and Low-Arctic Marine and Terrestrial Avian Community Changes: Comparative Isotopic (13C, 15N, and 34S) Studies in Alaska and Greenland

    NASA Astrophysics Data System (ADS)

    Causey, D.; Bargmann, N. A.; Burnham, K. K.; Burnham, J. L.; Padula, V. M.; Johnson, J. A.; Welker, J. M.

    2011-12-01

    Understanding the complex dynamics of environmental change in northern latitudes is of paramount importance today, given documented rapid shifts in sea ice, plant phenology, temperatures, deglaciation, and habitat fidelity. This knowledge is particularly critical for Arctic avian communities, which are integral components by which biological teleconnections are maintained between the mid and northern latitudes. Furthermore, Arctic birds are fundamental to Native subsistence lifestyles and a focus for conservation activities. Avian communities of marine and terrestrial Arctic environments represent a broad spectrum of trophic levels, from herbivores (eg., geese Chen spp.), planktivores (eg., auklets Aethia spp.), and insectivores (eg., passerines: Wheatears Oenanthe spp., Longspurs Calcarius spp.), to predators of marine invertebrates (eg., eiders Somateria spp.), nearshore and offshore fish (eg., cormorants Phalacrocorax spp, puffins Fratercula spp.), even other bird species (eg., gulls Larus spp., falcons Peregrinus spp.). This diversity of trophic interconnections is an integral factor in the dynamics of Arctic ecosystem ecology, and they are key indicators for the strength and trajectories of change. We are especially interested in their feeding ecology, using stable isotope-diet relations to examine historical diets and to predict future feeding ecology by this range of species. Since 2009, we have been studying the foodweb ecology using stable isotopes13C, δ15N, δ34S) of contemporaneous coastal and marine bird communities in High Arctic (Northwest Greenland) and Low Arctic (western Aleutian Islands, AK). We are quantifying the isotopic values of blood, organ tissues, and feathers, and have carried out comparisons between native and lipid-extracted samples. Although geographically distant, these communities comprise similar taxonomic and ecological congeners, including several species common to both (eg., Common Eider, Black-legged Kittiwake, Northern

  12. [Isotopic composition of the delta-18O--delta-13C from the otoliths of reef fish from Taiaro (Tuamotu, French Polynesia): isotopic and biological implications].

    PubMed

    Blamart, Dominique; Escoubeyrou, Karine; Juillet-Leclerc, Anne; Ouahdi, Rabia; Lecomte-Finiger, Raymonde

    2002-02-01

    Nuclei (larval stage) and outer parts (adult stage) of fish otoliths from the Taiaro closed lagoon (French Polynesia) and adjacent ocean have been analysed for the C-O isotopic compositions. delta 18O values of the nuclei of both populations indicate that isotopic equilibrium is reached. This implies that the lagoonal fish population has done its complete biological cycle in the lagoon and represents an adaptation in a closed system. delta 18O values of the outer parts show a slight isotopic disequilibrium (< 0.2@1000) interpreted in term of vital effect. All the delta 13C values exhibit a strong isotopic disequilibrium related to metabolic activity. PMID:11980181

  13. Easy Extraction Method To Evaluate δ13C Vanillin by Liquid Chromatography-Isotopic Ratio Mass Spectrometry in Chocolate Bars and Chocolate Snack Foods.

    PubMed

    Bononi, Monica; Quaglia, Giancarlo; Tateo, Fernando

    2015-05-20

    An easy extraction method that permits the use of a liquid chromatography-isotopic ratio mass spectrometry (LC-IRMS) system to evaluate δ(13)C of vanillin in chocolate products and industrial flavorings is presented. The method applies the determination of stable isotopes of carbon to discriminate between natural vanillin from vanilla beans and vanillin from other sources (mixtures from beans, synthesis, or biotechnology). A series of 13 chocolate bars and chocolate snack foods available on the Italian market and 8 vanilla flavorings derived from industrial quality control processes were analyzed. Only 30% of products considered in this work that declared "vanilla" on the label showed data that permitted the declaration "vanilla" according to European Union (EU) Regulation 1334/2008. All samples not citing "vanilla" or "natural flavoring" on the label gave the correct declaration. The extraction method is presented with data useful for statistical evaluation. PMID:25965784

  14. Optimization of 13C dynamic nuclear polarization: isotopic labeling of free radicals

    NASA Astrophysics Data System (ADS)

    Niedbalski, Peter; Parish, Christopher; Kiswandi, Andhika; Lumata, Lloyd

    Dynamic nuclear polarization (DNP) is a physics technique that amplifies the nuclear magnetic resonance (NMR) signals by transferring the high polarization of the electrons to the nuclear spins. Thus, the choice of free radical is crucial in DNP as it can directly affect the NMR signal enhancement levels, typically on the order of several thousand-fold in the liquid-state. In this study, we have investigated the efficiency of four variants of the well-known 4-oxo-TEMPO radical (normal 4-oxo-TEMPO plus its 15N-enriched and/or perdeuterated variants) for use in DNP of an important metabolic tracer [1-13C]acetate. Though the variants have significant differences in electron paramagnetic resonance (EPR) spectra, we have found that changing the composition of the TEMPO radical through deuteration or 15N doping yields no significant difference in 13C DNP efficiency at 3.35 T and 1.2 K. On the other hand, deuteration of the solvent causes a significant increase of 13C polarization that is consistent over all the 4-oxo-TEMPO variants. These findings are consistent with the thermal mixing model of DNP. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and the Robert A. Welch Foundation Grant No. AT-1877.

  15. Predicting outcomes of steady-state 13C isotope tracing experiments using Monte Carlo sampling

    PubMed Central

    2012-01-01

    Background Carbon-13 (13C) analysis is a commonly used method for estimating reaction rates in biochemical networks. The choice of carbon labeling pattern is an important consideration when designing these experiments. We present a novel Monte Carlo algorithm for finding the optimal substrate input label for a particular experimental objective (flux or flux ratio). Unlike previous work, this method does not require assumption of the flux distribution beforehand. Results Using a large E. coli isotopomer model, different commercially available substrate labeling patterns were tested computationally for their ability to determine reaction fluxes. The choice of optimal labeled substrate was found to be dependent upon the desired experimental objective. Many commercially available labels are predicted to be outperformed by complex labeling patterns. Based on Monte Carlo Sampling, the dimensionality of experimental data was found to be considerably less than anticipated, suggesting that effectiveness of 13C experiments for determining reaction fluxes across a large-scale metabolic network is less than previously believed. Conclusions While 13C analysis is a useful tool in systems biology, high redundancy in measurements limits the information that can be obtained from each experiment. It is however possible to compute potential limitations before an experiment is run and predict whether, and to what degree, the rate of each reaction can be resolved. PMID:22289253

  16. Mangrove isotopic (δ15N and δ13C) fractionation across a nitrogen vs. phosphorus limitation gradient

    USGS Publications Warehouse

    Mckee, Karen L.; Feller, Ilka C.; Popp, Marianne; Wanek, Wolfgang

    2002-01-01

    Mangrove islands in Belize are characterized by a unique switching from nitrogen (N) to phosphorus (P) limitation to tree growth from shoreline to interior. Fertilization has previously shown that Rhizophora mangle (red mangrove) fringe trees (5–6 m tall) growing along the shoreline are N limited; dwarf trees (!1.5 m tall) in the forestinterior are P limited; and transition trees (2–4 m tall) are co-limited by both N and P.  Growth patterns paralleled a landward decrease in soil flushing by tides and an increase in bioavailable N, but P availability remained consistently low across the gradient. Stable isotopic composition was measured in R. mangle leaves to aid in explaining this nutrient switching pattern and growth variation. Along control transects, leaf !15N decreased from "0.10‰ (fringe) to #5.38‰ (dwarf). The !15N of N-fertilized trees also varied spatially, but the values were consistently more negative (by $3‰) compared to control trees. Spatial variation in !15N values disappeared when the trees were fertilized with P, and values averaged "0.12‰, similar to that in control fringe trees. Neither variation in source inputs nor microbial fractionation could fully account for the observed patterns in !15N. The results instead suggest that the lower !15N values in transition and dwarf control trees were due to plant fractionation as a consequence of slower growth and lower N demand. P fertilization increased N demand and decreased fractionation. Although leaf !13C was unaffected by fertilization, values increased from fringe (#28.6‰) to transition (#27.9‰) to dwarf (#26.4‰) zones, indicating spatial variation in environmental stresses affecting stomatal conductance or carboxylation. The results thus suggest an interaction of external supply, internal demand, and plant ability to acquire nutrients under different hydro-edaphic conditions that vary across this tree-height gradient. The findings not only aid in understanding

  17. Isotope ratio mass spectrometry: delta13C and delta15 N analysis for tracing the origin of illicit drugs.

    PubMed

    Galimov, E M; Sevastyanov, V S; Kulbachevskaya, E V; Golyavin, A A

    2005-01-01

    Gas chromatography/combustion/mass spectrometry (GC-C-MS) and elemental analysis/mass spectrometry (EA-MS) techniques are proposed to estimate delta(13)C and delta(15)N values in heroin, morphine, cocaine and hemp leaves, for the purposes of tracing the geographical origins of seized drugs. The values of isotope ratios for pure drugs and drugs with impurities were compared. It was demonstrated that large samples (up to 3 x 10(-6) g C) were combusted completely, so that the results obtained were valid. The data are considered to be an essential supplement to a wide-scale database designed specifically for the delta(13)C and delta(15)N values of drugs. The potential forensic and academic significance of the results is discussed. PMID:15832288

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

    SciTech Connect

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

    1983-03-01

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

    PubMed

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

    2011-02-15

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

  20. Metabolic turnover rates of carbon and nitrogen stable isotopes in captive juvenile snakes.

    PubMed

    Fisk, Aaron T; Sash, Kim; Maerz, John; Palmer, William; Carroll, John P; Macneil, M Aaron

    2009-01-01

    Metabolic turnover rates (m) of delta(15)N and delta(13)C were assessed in different tissues of newly hatched captive-raised corn snakes (Elaphe guttata guttata) fed maintenance diets consisting of earthworms (Eisenia foetida) that varied substantially in delta(15)N (by 644 per thousand) and delta(13)C (by 5.0 per thousand). Three treatments were used during this 144 day experiment that consisted of the same diet throughout (control), shifting from a depleted to an enriched stable isotope signature diet (uptake), and shifting from an enriched to depleted stable isotope signature diet (elimination). Values of delta(13)C in the liver, blood, and muscle of the control snakes reached equilibrium with and were, respectively, 1.73, 2.25 and 2.29 greater than in their diet, this increase is called an isotopic discrimination factor (Deltadelta(13)C = delta(13)C(snake) - delta(13)C(food)). Values of delta(15)N in snake tissues did not achieve equilibrium with the diets in any of the exposures and thus Delta(15)N could not be estimated. Values of metabolic turnover rates (m) for delta(13)C and delta(15)N were greater in liver than in muscle and blood, which were similar, and relative results remained the same if the fraction of (15)N and (13)C were modeled. Although caution is warranted because equilibrium values of stable isotopes in the snakes were not achieved, values of m were greater for delta(13)C than delta(15)N, resulting in shorter times to dietary equilibrium for delta(13)C upon a diet shift, and for both stable isotopes in all tissues, greater during an elimination than in an uptake shift in diet stable isotope signature. Multiple explanations for the observed differences between uptake and elimination shifts raise new questions about the relationship between animal and diet stable isotope concentrations. Based on this study, interpretation of feeding ecology using stable isotopes is highly dependent on the kind of stable isotope, tissue, direction of diet switch

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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: <0.05 mm) were studied from each soil. A complete conventional analytical pyrolysis (Py-GC/MS) of these samples have been studied in detail (Jiménez-Morillo et al., 2015). Bulk isotopic analysis of stable light elements (δ15N, δ13C, δ18O and δD) revealed particular isotopic signatures showing differences related with the main vegetation cover and the different soil size fraction. All samples had a carbon isotopic signature between -26 and -29 ‰, which indicated that the organic matter in the two fractions of each soil sample derived from C3-type plants. The bulk δD isotopic signature in whole soil sample indicate a lower deuterium fractionation occurs in SOM under arboreal than under no-arboreal vegetation, this can be caused by the occurrence of a higher water evaporation rate under bush vegetation and/or to differences due to leaf morphology as previously described (Leaney et al., 1985). A δ15N vs. δ18O chart may provide some clues about N origin in the soil and particularly about the original source of nitrates (Kendall et al., 1996). In in all sample and size fractions our values are in the chart area corresponding to NO3 in precipitation, with lighter δ18O (c. 20 ‰) values compatible with fertilizers may be from adjacent crops. In addition we were able to assign δ13C and δD values for a number of

  2. The {sup 13}C-pocket structure in AGB models: constraints from zirconium isotope abundances in single mainstream SiC grains

    SciTech Connect

    Liu, Nan; Davis, Andrew M.; Pellin, Michael J.; Gallino, Roberto; Bisterzo, Sara; Savina, Michael R.

    2014-06-20

    We present postprocess asymptotic giant branch (AGB) nucleosynthesis models with different {sup 13}C-pocket internal structures to better explain zirconium isotope measurements in mainstream presolar SiC grains by Nicolussi et al. and Barzyk et al. We show that higher-than-solar {sup 92}Zr/{sup 94}Zr ratios can be predicted by adopting a {sup 13}C-pocket with a flat {sup 13}C profile, instead of the previous decreasing-with-depth {sup 13}C profile. The improved agreement between grain data for zirconium isotopes and AGB models provides additional support for a recent proposal of a flat {sup 13}C profile based on barium isotopes in mainstream SiC grains by Liu et al.

  3. The 13C-Pocket Structure in AGB Models: Constraints from Zirconium Isotope Abundances in Single Mainstream SiC Grains

    NASA Astrophysics Data System (ADS)

    Liu, Nan; Gallino, Roberto; Bisterzo, Sara; Davis, Andrew M.; Savina, Michael R.; Pellin, Michael J.

    2014-06-01

    We present postprocess asymptotic giant branch (AGB) nucleosynthesis models with different 13C-pocket internal structures to better explain zirconium isotope measurements in mainstream presolar SiC grains by Nicolussi et al. and Barzyk et al. We show that higher-than-solar 92Zr/94Zr ratios can be predicted by adopting a 13C-pocket with a flat 13C profile, instead of the previous decreasing-with-depth 13C profile. The improved agreement between grain data for zirconium isotopes and AGB models provides additional support for a recent proposal of a flat 13C profile based on barium isotopes in mainstream SiC grains by Liu et al.

  4. δD and δ13C analyses of atmospheric volatile organic compounds by thermal desorption gas chromatography isotope ratio mass spectrometry.

    PubMed

    von Eckstaedt, Christiane Vitzthum; Grice, Kliti; Ioppolo-Armanios, Marisa; Chidlow, Geoff; Jones, Mark

    2011-09-16

    This paper describes the establishment of a robust method to determine compound specific δD and δ(13)C values of volatile organic compounds (VOCs) in a standard mixture ranging between C(6) and C(10) and was applied to various complex emission samples, e.g. from biomass combustion and car exhaust. A thermal desorption (TD) unit was linked to a gas chromatography isotope ratio mass spectrometer (GC-irMS) to enable compound specific isotope analysis (CSIA) of gaseous samples. TenaxTA was used as an adsorbent material in stainless steel TD tubes. We determined instrument settings to achieve a minimal water background level for reliable δD analysis and investigated the impact of storage time on δD and δ(13)C values of collected VOCs (176 days and 40 days of storage, respectively). Most of the standard compounds investigated showed standard deviations (SD)<6‰ (δD) when stored for 148 days at 4 °C. However, benzene revealed occasionally D depleted values (21‰ SD) for unknown reasons. δ(13)C analysis demonstrated that storage of 40 days had no effect on VOCs investigated. We also showed that breakthrough (benzene and toluene, 37% and 7%, respectively) had only a negligible effect (0.7‰ and 0.4‰, respectively) on δ(13)C values of VOCs on the sample tube. We established that the sample portion collected at the split flow effluent of the TD unit can be used as a replicate sample for isotope analysis saving valuable sampling time and resources. We also applied TD-GC-irMS to different emission samples (biomass combustion, petrol and diesel car engines exhaust) and for the first time δD values of atmospheric VOCs in the above range are reported. Significant differences in δD of up to 130‰ were observed between VOCs in emissions from petrol car engine exhaust and biomass combustion (Karri tree). However, diesel car emissions showed a high content of highly complex unresolved mixtures thus a baseline separation of VOCs was not achieved for stable hydrogen

  5. Stable Carbon and Nitrogen isoscapes of the California Coast: integrated δ15N and δ13C of suspended particulate organic matter inferred from tissues of the California Mussel (mytilus californianus)

    NASA Astrophysics Data System (ADS)

    Vokhshoori, N. L.; McCarthy, M. D.

    2011-12-01

    Spatial maps of isotopic variability in a single species, or isoscapes, can characterize the natural variability in carbon (C) and nitrogen (N) isotope ratios across ecosystems on broad spatial scales, trace the signature of a source across a given area, as well as constrain animal migration patterns (Graham et al. 2002). In this study, isoscapes of stable carbon (13C) and nitrogen (15N) isotopes were constructed using intertidal mussels for northeast Pacific coastal waters of California. In this region biogeochemical cycling is primarily controlled by upwelling intensity and large-scale transport of the California Current System (CCS). We hypothesize that sampling specific tissues of filter-feeding organisms can provide an integrated measure of variation in 15N and 13C of the suspended particulate organic matter (POM) pool vs. latitude within the CCS, as well indicate main sources of both organic C and N to littoral food webs. California mussels (mytilus californianus) were collected from 28 sites between Coos Bay, OR and La Jolla, CA in the winter of 2009-2010 and summer of 2011, and adductor tissue was analyzed for δ13C and δ15N. Mussel size classes were chosen to provide ~ 1 yr integrated signal. Spatial trends in δ15N from the winter sampling show a strong linear trend in increasing δ15N values with latitude north to south (δ15N values range from 7 % to 12%) consistent with slowly attenuating northward transport of 15N-depleted nitrate via California Undercurrent (Altabet et al. 1999). The δ13C values have no strong north to south correlation, but exhibit strong location-specific variability. The δ13C values range between -13 % and -18%. We propose the site-specific signature of δ13C indicates relative source of primary productin to POM at a given region (i.e. kelp, phytoplankton, zooplankton). Overall, these results suggest that isoscapes for filter-feeding organisms may offer a more accurate integrated picture of 15N and 13C values of POM than is

  6. Measurement of intact sulfate and glucuronide phytoestrogen conjugates in human urine using isotope dilution liquid chromatography-tandem mass spectrometry with [13C(3)]isoflavone internal standards.

    PubMed

    Clarke, Don B; Lloyd, Antony S; Botting, Nigel P; Oldfield, Mark F; Needs, Paul W; Wiseman, Helen

    2002-10-01

    A method has been developed for the analysis of phytoestrogens and their conjugates in human urine using liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Stable isotopically labeled [13C(3)]daidzein and [13C(3)]genistein were synthesized and used as internal standards for isotope dilution mass spectrometry. Free aglycons and intact glucuronide, sulfate, diglucuronide, disulfate, and mixed sulfoglucuronide conjugates of isoflavones and lignans were observed in naturally incurred urine samples. Sample pretreatment was not necessary, other than addition of internal standards and pH adjustment. Urine was injected directly onto the analytical column. The limits of detection were generally <50ng/ml, precision was generally <10% CV for conjugates. Total hydrolyzed daidzein and genistein were measured against quality assurance urine sample and were accurate to within 12%. The accuracy of conjugate measurement can not be ascertained, as no reference samples are available. The mean sum of daidzein and its conjugates was within 20% of the hydrolyzed value. Concentrations of the free aglycons of up to 22% of genistein and 18% of daidzein were observed. The average pattern was ca. 54% 7-glucuronide, 25% 4(')-glucuronide, 13% monosulfates, 7% free daidzein, 0.9% sulfoglucuronides, 0.4% diglucuronide, and <0.1% disulfate. Selective enzymatic deconjugation with glucuronidase and mixed glucuronidase/sulfatase were used to validate the accuracy of the quantitation of the intact daidzein conjugates. There were no apparent sex differences, or conditioning effects on the conjugation profile of isoflavones after chronic dosing. PMID:12381375

  7. Carbon Isotope Fractionation Between CO Gas and CO Ice with Implications for 12C/13C of the Interstellar Medium and the Early Solar System

    NASA Astrophysics Data System (ADS)

    Young, E. D.; Schauble, E. A.

    2011-03-01

    A model for carbon-isotope fractionation between CO ice and gas is presented. The model includes a self-consistent portrayal of the kinetics of partitioning of 12C and 13C between CO ice and gas. Ice-gas carbon exchange may be a primary control for 12C/13C.

  8. Miniature Laser Spectrometer for Stable Isotope Measurements

    NASA Technical Reports Server (NTRS)

    Becker, J. F.; Kojiro, D. R.

    1999-01-01

    As a first step in successfully measuring carbon isotopes optically we have previously demonstrated the measurement of C-13/C-12 to a precision of 0.1% using a tunable diode laser and CO2 spectral lines in the 2300/cm spectral region. This precision of 0.1% (1 per mil) for carbon isotopes is a value sufficiently precise to provide important isotopic data of interest to astrobiologists. The precision presently attainable in gases is sufficient to permit our instrument to be used in the measurement of isotopic ratios of interest to astrobiologists as well as geologists and planetary scientists.

  9. Quantitation of metabolic compartmentation in hyperammonemic brain by natural abundance 13C-NMR detection of 13C-15N coupling patterns and isotopic shifts.

    PubMed

    Lapidot, A; Gopher, A

    1997-02-01

    In the present study, the removal of cerebral ammonia by glutamine synthetase (GS) and by reductive amination of 2-oxoglutarate by glutamate dehydrogenase in the presence of an amino donor group, was determined in hyperammonemic rabbit brains. The 15N enrichments of brain metabolite alpha-amino and amide positions of glutamine, glutamate, and alanine were determined by the indirect detection of 15N-labeled compounds of the 13C-15N spin coupling patterns of natural abundance 13C-NMR spectra. The 13C-NMR spectra of brain extracts were obtained from rabbits infused with 15NH4Cl with or without intraperitoneal infusion of the GS inhibitor, L-methionine DL-sulfoximine, in a reasonable acquisition time period. When 15NH4Cl was infused, [5-15N]glutamine and [2-15N]glutamine concentrations reached 5.2 mumol/100 mg protein and 3.6 mumol/100 mg protein, respectively, which indicates the relatively high activity of reductive amination of 2-oxoglutarate in the glutamate dehydrogenase reaction. The low concentration of [2-15N]glutamate, which is about 30% of that of [2-15N]glutamine obtained in this study, suggests that very little glutamine serves as a precursor of neuronal glutamate. When GS was inhibited by L-methionine DL-sulfoximine, a flux of 15NH4+ via the residual activity of GS was accompanied by an apparent increase of [2-15N]glutamate and [15N]alanine concentrations (2.9 mumol/100 mg protein and 1.8 mumol/100 mg protein, respectively). These findings and those obtained from 13C-13C isotopomer analysis (Lapidot and Gopher, 1994b) suggest that astrocytic 2-oxoglutarate is partially utilized (together with an amino group donor) as a precursor for neuronal glutamate in the hyperammonemic brain when GS is inhibited. This process can partly replace GS activity in metabolizing ammonia in the hyperammonemic rabbit brain. PMID:9057821

  10. Stable Isotope Laser Spectrometer for Exploration of Mars

    NASA Technical Reports Server (NTRS)

    Sauke, Todd B.; Becker, Joseph F.

    1998-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  12. Highly enriched multiply-labeled stable isotopic compounds as atmospheric tracers

    DOEpatents

    Goldblatt, M.; McInteer, B.B.

    1974-01-29

    Compounds multiply-labeled with stable isotopes and highly enriched in these isotopes are readily capable of detection in tracer experiments involving high dilutions. Thus, for example, /sup 13/C/sup 18/O/sub 2/ provides a useful tracer for following atmospheric pol lution produced as a result of fossil fuel burning. (Official Gazette)

  13. Uses of stable isotopes in fish ecology

    EPA Science Inventory

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

  14. The suitability of the dual isotope approach (δ13C and δ18O) in tree ring studies

    NASA Astrophysics Data System (ADS)

    Siegwolf, Rolf; Saurer, Matthias

    2016-04-01

    The use of stable isotopes, complementary to tree ring width data in tree ring research has proven to be a powerful tool in studying the impact of environmental parameters on tree physiology and growth. These three proxies are thus instrumental for climate reconstruction and improve the understanding of underlying causes of growth changes. In various cases, however, their use suggests non-plausible interpretations. Often the use of one isotope alone does not allow the detection of such "erroneous isotope responses". A careful analysis of these deviating results shows that either the validity of the carbon isotope discrimination concept is no longer true (Farquhar et al. 1982) or the assumptions for the leaf water enrichment model (Cernusak et al., 2003) are violated and thus both fractionation models are not applicable. In this presentation we discuss such cases when the known fractionation concepts fail and do not allow a correct interpretation of the isotope data. With the help of the dual isotope approach (Scheidegger et al.; 2000) it is demonstrated, how to detect and uncover the causes for such anomalous isotope data. The fractionation concepts and their combinations before the background of CO2 and H2O gas exchange are briefly explained and the specific use of the dual isotope approach for tree ring data analyses and interpretations are demonstrated. References: Cernusak, L. A., Arthur, D. J., Pate, J. S. and Farquhar, G. D.: Water relations link carbon and oxygen isotope discrimination to phloem sap sugar concentration in Eucalyptus globules, Plant Physiol., 131, 1544-1554, 2003. Farquhar, G. D., O'Leary, M. H. and Berry, J. A.: On the relationship between carbon isotope discrimination and the intercellular carbon dioxide concentration in leaves, Aust. J. Plant Physiol., 9, 121-137, 1982. Scheidegger, Y., Saurer, M., Bahn, M. and Siegwolf, R.: Linking stable oxygen and carbon isotopes with stomatal conductance and photosynthetic capacity: A conceptual model

  15. Modelling the 13C and 12C isotopes of inorganic and organic carbon in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Gustafsson, Erik; Mörth, Carl-Magnus; Humborg, Christoph; Gustafsson, Bo G.

    2015-08-01

    In this study, 12C and 13C contents of all carbon containing state variables (dissolved inorganic and organic carbon, detrital carbon, and the carbon content of autotrophs and heterotrophs) have for the first time been explicitly included in a coupled physical-biogeochemical Baltic Sea model. Different processes in the carbon cycling have distinct fractionation values, resulting in specific isotopic fingerprints. Thus, in addition to simulating concentrations of different tracers, our new model formulation improves the possibility to constrain the rates of processes such as CO2 assimilation, mineralization, and air-sea exchange. We demonstrate that phytoplankton production and respiration, and the related air-sea CO2 fluxes, are to a large degree controlling the isotopic composition of organic and inorganic carbon in the system. The isotopic composition is further, but to a lesser extent, influenced by river loads and deep water inflows as well as transformation of terrestrial organic carbon within the system. Changes in the isotopic composition over the 20th century have been dominated by two processes - the preferential release of 12C to the atmosphere in association with fossil fuel burning, and the eutrophication of the Baltic Sea related to increased nutrient loads under the second half of the century.

  16. Investigation of the enzymatic mechanism of yeast orotidine-5'-monophosphate decarboxylase using sup 13 C kinetic isotope effects

    SciTech Connect

    Smiley, J.A.; Bell, J.B.; Jones, M.E. ); Paneth, P.; O'Leary, M.H. )

    1991-06-25

    Orotidine-5'-monophosphate decarboxylase (ODCase) from Saccharomyces cerevisiae displays an observed {sup 13}C kinetic isotope effect of 1.0247 {plus minus} 0.0008 at 25 C, pH 6.8. The observed isotope effect is sensitive to changes in the reaction medium, such as pH, temperature, or glycerol content. The value of 1.0494 {plus minus} 0.0006 measured at pH 4.0, 25 C, is not altered significantly by temperature or glycerol, and thus the intrinsic isotope effect for the reaction is apparently being observed under these conditions and decarboxylation is almost entirely rate-determining. These data require a catalytic mechanism with freely reversible binding and one in which a very limited contribution to the overall rate is made by chemical steps preceding decarboxylation; the zwitterion mechanism of Beak and Siegel, which involves only protonation of the pyrimidine ring, is such a mechanism. With use of an intrinsic isotope effect of 1.05, a partitioning factor of less than unity is calculated for ODCase at pH 6.0, 25 C. A quantitative kinetic analysis using this result excludes the possibility of an enzymatic mechanism involving covalent attachment of an enzyme nucleophile to C-5 of the pyrimidine ring. These data fit a kinetic model in which an enzyme proton necessary for catalysis is titrated at high pH, thus providing evidence for the catalytic mechanism of Beak and Siegal.

  17. High-precision optical measurements of 13C/12C isotope ratios in organic compounds at natural abundance

    PubMed Central

    Zare, Richard N.; Kuramoto, Douglas S.; Haase, Christa; Tan, Sze M.; Crosson, Eric R.; Saad, Nabil M. R.

    2009-01-01

    A continuous-flow cavity ring-down spectroscopy (CRDS) system integrating a chromatographic separation technique, a catalytic combustor, and an isotopic 13C/12C optical analyzer is described for the isotopic analysis of a mixture of organic compounds. A demonstration of its potential is made for the geochemically important class of short-chain hydrocarbons. The system proved to be linear over a 3-fold injection volume dynamic range with an average precision of 0.95‰ and 0.67‰ for ethane and propane, respectively. The calibrated accuracy for methane, ethane, and propane is within 3‰ of the values determined using isotope ratio mass spectrometry (IRMS), which is the current method of choice for compound-specific isotope analysis. With anticipated improvements, the low-cost, portable, and easy-to-use CRDS-based instrumental setup is poised to evolve into a credible challenge to the high-cost and complex IRMS-based technique. PMID:19564619

  18. High-resolution δ 13C intratooth profiles in bovine enamel: Implications for mineralization pattern and isotopic attenuation

    NASA Astrophysics Data System (ADS)

    Zazzo, Antoine; Balasse, Marie; Patterson, William P.

    2005-07-01

    We present the first high-resolution carbon isotope and carbonate content profiles generated through the thickness of enamel from a steer fed C 3- then C 4-dominant food. Carbonate contents decrease by ˜2 wt% from the enamel surface to the innermost enamel layer, and each carbon isotope profile shows a mixture of enamel portions mineralized over several months. Downward and outward increasing contribution of C 4 food to the enamel δ 13C values reveal two components of the mineralization gradient: a vertical component from the tip of the tooth crown to the neck, and a horizontal component from the enamel-dentine junction to the outer enamel. We use our results to infer mineralization parameters for bovines and to calculate expected isotopic attenuations for an array of environmental inputs and microsampling strategies, using the model developed by Passey and Cerling [ Geochim. Cosmochim. Acta. 66 (2002) 3225-3234]. Although it seems unlikely that any strategy will perfectly isolate discrete time slices, sampling the innermost enamel layer might offer the advantage of significantly reducing the isotope damping that would become independent of the structure of the input signal.

  19. Quantification of soy protein using the isotope method (δ(13)C and δ(15)N) for commercial brands of beef hamburger.

    PubMed

    Ducatti, Rhani; de Almeida Nogueira Pinto, José Paes; Sartori, Maria Márcia Pereira; Ducatti, Carlos

    2016-12-01

    Hamburgers (beef patties) may be adulterated through the overuse of protein extenders. Among vegetables, soy protein is the best substitute for animal protein. These ingredients help to reduce the cost of producing a final product, and they maximize profits for fraudulent industries. Moreover, the ingestion of soy or other non-meat proteins by allergic individuals may present a health risk. In addition, monitoring by supervisory bodies is hampered by a lack of appropriate analytical methodologies. Within this context, the aim of this study was to determine and quantify the levels of added soy protein by determination of (15)N and (13)C stable isotopes. A total of 100 beef hamburger samples from 10 commercial brands were analyzed. Only three samples of the G brand were within the standards set the Brazilian legislation. The remaining 97 samples from 10 commercial brands contained >4% soy protein; therefore, they are adulterated and not in compliance with the current legislation. PMID:27501234

  20. Stable isotope ratio measurements of royal jelly samples for controlling production procedures: impact of sugar feeding.

    PubMed

    Daniele, Gaëlle; Wytrychowski, Marine; Batteau, Magali; Guibert, Sylvie; Casabianca, Hervé

    2011-07-30

    The carbon and nitrogen stable ratios of royal jelly (RJ) samples from various origins are determined using an elemental analyser linked online to an isotope ratio mass spectrometer to evaluate authenticity and adulteration. The (13)C/(12)C and (15)N/(14)N stable isotope ratios are measured in more than 500 RJs (domestic, imported and derived from feeding experiments) in order to obtain isotopic measurements that take into account seasonal, botanical and geographical effects. Authenticity intervals are established for traditional beekeeping practices, without feeding, in the range -22.48 to -27.90‰ for δ(13)C. For these samples, the δ(15)N values range from -1.58 to 7.98‰, depending on the plant sources of pollen and nectar. The δ(13)C values of the commercial samples vary from -18.54 to -26.58‰. High δ(13)C values are typical of sugar cane or corn syrups which have distinctive isotopic (13)C signatures because both plants use the C4 photosynthetic cycle, in contrast to most RJs which are derived from C3 plants. These differences in the (13)C-isotopic composition allow the detection of the addition of such sugars. RJs from traditional sources and from industrial production by sugar feeding are thus successfully distinguished. PMID:21698675

  1. Regional Modeling of Stable Carbon Isotope ratio of non Methane Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Dehghan, F.-

    2004-05-01

    The study of stable isotope ratio (δ 13C) can be useful to understand the history of an air parcel that include sources, mixing and photochemical processing. The 3D regional model (MC2AQ) was modified (with two different resolution, 21.2km and 5.3km) to include isotope information for Propene, Toluene, Propane, Benzene, Xylenes, and Isoprene. These compounds (both 12C and 13C) were included as tracers in the model reacting only with OH, with no feedback on the main chemistry. This model structure can help to constrain the OH concentration. The kinetic isotope effect (KIE) was included for the reactions with OH. The results show that the δ 13C varies with emissions: when emissions are high the δ 13C is close to that of the sources, and as the air parcel moves away from the sources the δ 13C gets heavier due to the chemical processing. We see a clear diurnal pattern in the δ 13C after removing the effect of the sources. This is an indication of the effect of the processing by OH. The results show that the vertical gradient of δ 13C depends on the lifetime and the KIE of the hydrocarbons. The back trajectories of the stable isotope ratio (δ 13C) were determined to study the history of each hydrocarbon independently using the average photochemical age. The results can help in the determination of the possible sources of individual hydrocarbons and the effects of mixing and dilution during the parcel advection. The back trajectory analysis of δ 13C provides information of the possible locations of the sources of the compounds being investigated. The model was also set up to study the effect of the different emission type (area sources or point sources) of NMHCs on δ 13C, using this method can help us to identify the fractionation and location of these two sources.

  2. Isotopic variation ( δ15N, δ13C, and δ34S) with body size in post-larval estuarine consumers

    NASA Astrophysics Data System (ADS)

    Marie Wilson, Rachel; Chanton, Jeffrey; Lewis, Graham; Nowacek, Douglas

    2009-07-01

    Stable isotope analyses were conducted on fish and crabs in Apalachicola Bay, Florida (USA) to determine whether δ15N values are correlated with length within these species. Our objective was to define the smallest trophic unit of the system as a prelude to further isotopic evaluations of consumer trophic level in Apalachicola Bay. In some cases, the smallest trophic unit is the individual species; however, previous gut content analysis on organisms in this system indicated that subdivision by size class within species might be required. However, over the size ranges observed, there was no systematic change in the δ15N values of individual consumers. Analysis of the δ13C and δ34S values of these species reveal no obvious shifts in the utilization of organic matter sources with length that could be obscuring a trend in the δ15N signal. We find no isotopic evidence for a systematic trophic level increase within the species examined over the size ranges observed in this estuary. These results indicate that species rather than size class is the best predictor of trophic habit among these Apalachicola Bay consumers.

  3. Partitioning Net Ecosystem Carbon Exchange Into net Assimilation and Respiration With Canopy-scale Isotopic Measurements: an Error Propagation Analysis With Both 13C and 18O Data

    NASA Astrophysics Data System (ADS)

    Peylin, P.; Ogee, J.; Cuntz, M.; Bariac, T.; Ciais, P.; Brunet, Y.

    2003-12-01

    Stable CO2 isotope measurements are increasingly used to partition the net CO2 exchange between terrestrial ecosystems and the atmosphere in terms of non-foliar respiration (FR) and gross photosynthesis (FA). However the accuracy of the partitioning strongly depends on the isotopic disequilibrium between these two gross fluxes and a rigorous estimation of the errors on FA and FR is needed. In this study we account and propagate uncertainties on all terms in the mass balance equations for total and "labeled" CO2 in order to get precise estimates of the errors on FA and FR. We applied our method to a maritime pine forest in the Southwest of France. Using the δ 13C-CO2 and CO2 measurements, we show that the resulting uncertainty associated to the gross fluxes can be as large as 4 æmol m-2 s-1. In addition, even if we could get more precise estimates of the isoflux and the isotopic signature of FA we show that this error would not be significantly reduced. This is because the isotopic disequilibrium between FA and FR is around 2-3‰ , i.e. the order of magnitude of the uncertainty on the isotopic signature of FR (δ R). With δ 18O-CO2 and CO2 measurements, the uncertainty associated to the gross fluxes lies also around 4 æmol m-2 s-1. On the other hand, it could be dramatically reduced if we were able to get more precise estimates of the CO18O isoflux and the associated discrimination during photosynthesis. This is because the isotopic disequilibrium between FA and FR is large, of the order of 10-15‰ , i.e. much larger than the uncertainty on δ R. The isotopic disequilibrium between FA and FR or the uncertainty on δ R vary among ecosystems and over the year. Our approach may help to choose the best strategy to study the carbon budget of a given ecosystem using stable isotopes.

  4. Complementary constraints from carbon (13C) and nitrogen (15N) isotopes on the glacial ocean's soft-tissue biological pump

    NASA Astrophysics Data System (ADS)

    Schmittner, A.; Somes, C. J.

    2016-06-01

    A three-dimensional, process-based model of the ocean's carbon and nitrogen cycles, including 13C and 15N isotopes, is used to explore effects of idealized changes in the soft-tissue biological pump. Results are presented from one preindustrial control run (piCtrl) and six simulations of the Last Glacial Maximum (LGM) with increasing values of the spatially constant maximum phytoplankton growth rate μmax, which accelerates biological nutrient utilization mimicking iron fertilization. The default LGM simulation, without increasing μmax and with a shallower and weaker Atlantic Meridional Overturning Circulation and increased sea ice cover, leads to 280 Pg more respired organic carbon (Corg) storage in the deep ocean with respect to piCtrl. Dissolved oxygen concentrations in the colder glacial thermocline increase, which reduces water column denitrification and, with delay, nitrogen fixation, thus increasing the ocean's fixed nitrogen inventory and decreasing δ15NNO3 almost everywhere. This simulation already fits sediment reconstructions of carbon and nitrogen isotopes relatively well, but it overestimates deep ocean δ13CDIC and underestimates δ15NNO3 at high latitudes. Increasing μmax enhances Corg and lowers deep ocean δ13CDIC, improving the agreement with sediment data. In the model's Antarctic and North Pacific Oceans modest increases in μmax result in higher δ15NNO3 due to enhanced local nutrient utilization, improving the agreement with reconstructions there. Models with moderately increased μmax fit both isotope data best, whereas large increases in nutrient utilization are inconsistent with nitrogen isotopes although they still fit the carbon isotopes reasonably well. The best fitting models reproduce major features of the glacial δ13CDIC, δ15N, and oxygen reconstructions while simulating increased Corg by 510-670 Pg compared with the preindustrial ocean. These results are consistent with the idea that the soft-tissue pump was more efficient

  5. Isotope Substitution Effect in Polyatomic Molecules on the Example of 13C2H4 ← 12C2H4 Substitution

    NASA Astrophysics Data System (ADS)

    Bekhtereva, E. S.; Gromova, O. V.; Berezkin, K. B.; Kashirina, N. V.; Konov, I. A.; Bauerecker, S.

    2016-03-01

    General points of the theory of isotope substitution are applied to an analysis of the isotope substitution effect for the substitution 13C2H4←12C2H4 in the ethylene molecule. On the basis of the isotope relations so obtained, numerical predictions of band centers and the most significant rotational, centrifugal, and resonance parameters are made here for the first time for the four lower vibrational states of the 13C2H4 molecule, which can be used to analyze the complicated vibrational-rotational structure of the above-mentioned vibrational states.

  6. Isotopically nonstationary 13C flux analysis of changes in Arabidopsis thaliana leaf metabolism due to high light acclimation.

    PubMed

    Ma, Fangfang; Jazmin, Lara J; Young, Jamey D; Allen, Doug K

    2014-11-25

    Improving plant productivity is an important aim for metabolic engineering. There are few comprehensive methods that quantitatively describe leaf metabolism, although such information would be valuable for increasing photosynthetic capacity, enhancing biomass production, and rerouting carbon flux toward desirable end products. Isotopically nonstationary metabolic flux analysis (INST-MFA) has been previously applied to map carbon fluxes in photoautotrophic bacteria, which involves model-based regression of transient (13)C-labeling patterns of intracellular metabolites. However, experimental and computational difficulties have hindered its application to terrestrial plant systems. We performed in vivo isotopic labeling of Arabidopsis thaliana rosettes with (13)CO2 and estimated fluxes throughout leaf photosynthetic metabolism by INST-MFA. Plants grown at 200 µmol m(-2)s(-1) light were compared with plants acclimated for 9 d at an irradiance of 500 µmol⋅m(-2)⋅s(-1). Approximately 1,400 independent mass isotopomer measurements obtained from analysis of 37 metabolite fragment ions were regressed to estimate 136 total fluxes (54 free fluxes) under each condition. The results provide a comprehensive description of changes in carbon partitioning and overall photosynthetic flux after long-term developmental acclimation of leaves to high light. Despite a doubling in the carboxylation rate, the photorespiratory flux increased from 17 to 28% of net CO2 assimilation with high-light acclimation (Vc/Vo: 3.5:1 vs. 2.3:1, respectively). This study highlights the potential of (13)C INST-MFA to describe emergent flux phenotypes that respond to environmental conditions or plant physiology and cannot be obtained by other complementary approaches. PMID:25368168

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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: <0.05 mm) were studied from each soil. A complete conventional analytical pyrolysis (Py-GC/MS) of these samples have been studied in detail (Jiménez-Morillo et al., 2015). Bulk isotopic analysis of stable light elements (δ15N, δ13C, δ18O and δD) revealed particular isotopic signatures showing differences related with the main vegetation cover and the different soil size fraction. All samples had a carbon isotopic signature between -26 and -29 ‰, which indicated that the organic matter in the two fractions of each soil sample derived from C3-type plants. The bulk δD isotopic signature in whole soil sample indicate a lower deuterium fractionation occurs in SOM under arboreal than under no-arboreal vegetation, this can be caused by the occurrence of a higher water evaporation rate under bush vegetation and/or to differences due to leaf morphology as previously described (Leaney et al., 1985). A δ15N vs. δ18O chart may provide some clues about N origin in the soil and particularly about the original source of nitrates (Kendall et al., 1996). In in all sample and size fractions our values are in the chart area corresponding to NO3 in precipitation, with lighter δ18O (c. 20 ‰) values compatible with fertilizers may be from adjacent crops. In addition we were able to assign δ13C and δD values for a number of

  8. Late Holocene monsoon climate of northeastern Taiwan inferred from elemental (C, N) and isotopic13C, δ15N) data in lake sediments

    NASA Astrophysics Data System (ADS)

    Selvaraj, Kandasamy; Wei, Kuo-Yen; Liu, Kon-Kee; Kao, Shuh-Ji

    2012-03-01

    Little information exists about centennial-scale climate variability on oceanic islands in the western Pacific where the East Asian monsoon (EAM) strongly influences the climate, mountain ecosystem and the society. In this study, we investigate a 168 cm long sediment core recovered from Emerald Peak Lake in subalpine NE Taiwan for the contents of grain size, total organic carbon (TOC), C/N ratio, and stable isotopes13C and δ15N) to reconstruct the monsoon climate and vegetation density during the late Holocene. Six radiocarbon (14C) ages obtained on plant remains used for the chronology indicate that the sediment core has been accumulated since ˜3770 cal BP with a mean sedimentation rate of 44.6 cm/ka. The sub-centennial resolution of our proxy records reveals strong fluctuations of the EAM and vegetation density for the past ˜3770 cal BP. The greater contents of coarse and medium sediments with overall decreasing trends from 3770 to 2000 cal BP suggest an increasing fine sediment influx from the catchment likely due to an increasing lake water level. Although low TOC content, C/N ratio, and enriched δ13C values in bulk and fine sediments during this interval suggest a sparsely vegetated catchment, increasing trends of TOC content and C/N ratio together with decreasing trends of δ13C and δ15N values indicate a strengthening pattern of summer monsoon. This is in contrast to a decreasing monsoon strength inferred from Dongge Cave δ18O record at that time, supporting the idea of anti-phasing of summer EAM and Indian summer monsoon. Since 2000 cal BP, higher content of fine sediments with high TOC content and C/N ratio but relatively depleted δ13C and low δ15N values suggest a high but stable lake water level and dense C3 plants, consistent with a stronger summer monsoon in a wet climate. Within this general trend, we interpret a prominent change of proxy parameters in sediments from ˜560 to 150 cal BP, as subtropical evidence for the Little Ice Age in NE

  9. Substitution of stable isotopes in Chlorella

    NASA Technical Reports Server (NTRS)

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

    1969-01-01

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

  10. Stable Isotope Signatures for Microbial Forensics

    SciTech Connect

    Kreuzer, Helen W.

    2012-01-03

    The isotopic distribution of the atoms composing the molecules of microorganisms is a function of the substrates used by the organisms. The stable isotope content of an organism is fixed so long as no further substrate consumption and biosynthesis occurs, while the radioactive isotopic content decays over time. The distribution of stable isotopes of C, N, O and H in heterotrophic microorganisms is a direct function of the culture medium, and therefore the stable isotope composition can be used to associate samples with potential culture media and also with one another. The 14C content depends upon the 14C content, and therefore the age, of the organic components of the culture medium, as well as on the age of the culture itself. Stable isotope signatures can thus be used for sample matching, to associate cultures with specific growth media, and to predict characteristics of growth media.

  11. The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS

    NASA Astrophysics Data System (ADS)

    Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2007-11-01

    We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyby) and 83° N (T4 flyby) at 0.5 cm -1 resolution. The spectral range 1210-1310 cm -1 was used to retrieve the temperature profile in the range 145-490 km at 13° S and 165-300 km at 83° N. These two temperature profiles were then incorporated in the atmospheric model to retrieve the abundance profile of H 12C 14N, H 13CN and HC 15N from their bands at 713, 706 and 711 cm -1, respectively. The HCN abundance profile was retrieved in the range 90-460 km at 15° S and 165-305 km at 83° N. There is no evidence for vertical variations of the isotopic ratios. Constraining the isotopic abundance profiles to be proportional to the HCN one, we find C12/C13=89-18+22 at 15° S, and 68-12+16 at 83° N, two values that are statistically consistent. A combination of these results yields a 12C/ 13C value equal to 75±12. This global result, as well as the 15° S one, envelop the value in Titan's methane ( 82.3±1) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784] measured at 10° S and is slightly lower than the terrestrial inorganic standard value (89). The 14N/ 15N isotopic ratio is found equal to 56-13+16 at 15° S and 56-9+10 at 83° N. Combining the two values yields 14N/ 15N = 56 ± 8, which corresponds to an enrichment in 15N of about 4.9 compared with the terrestrial ratio. These results agree with the values obtained from previous ground-based millimeter observations [Hidayat, T., Marten, A., Bézard, B., Gautier, D., Owen, T., Matthews, H.E., Paubert, G., 1997. Icarus 126, 170-182; Marten, A., Hidayat, T., Biraud, Y., Moreno, R., 2002. Icarus 158, 532-544]. The 15N/ 14N ratio found in HCN is ˜3 times higher than in N 2 [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779

  12. Rapid Stable Isotope Turnover of Larval Fish in a Lake Superior Coastal Wetland: Implications for Diet and Life History Studies

    EPA Science Inventory

    Trophic linkages of larval fish in Lake Superior coastal wetlands, rivers and embayments can be identified using naturally occurring differences in the stable isotope ratios of nitrogen (15N:14N, ?15N) and carbon (13C:12C, ?13C). We sampled pelagic fish larvae weekly during sprin...

  13. Combining position-specific 13C labeling with compound-specific isotope analysis: first steps towards soil fluxomics

    NASA Astrophysics Data System (ADS)

    Dippold, Michaela; Kuzyakov, Yakov

    2015-04-01

    Understanding the soil organic matter (SOM) dynamics is one of the most important challenges in soil science. Transformation of low molecular weight organic substances (LMWOS) is a key step in biogeochemical cycles because 1) all high molecular substances pass this stage during their decomposition and 2) only LMWOS will be taken up by microorganisms. Previous studies on LMWOS were focused on determining net fluxes through the LMWOS pool, but they rarely identified transformations. As LMWOS are the preferred C and energy source for microorganisms, the transformations of LMWOS are dominated by biochemical pathways of the soil microorganisms. Thus, understanding fluxes and transformations in soils requires a detailed knowledge on the biochemical pathways and its controlling factors. Tracing C fate in soil by isotopes became on of the most applied and promising biogeochemistry tools. Up to now, studies on LMWOS were nearly exclusively based on uniformly labeled organic substances i.e. all C atoms in the molecules were labeled with 13C or 14C. However, this classical approach did not allow the differentiation between use of intact initial substances in any process, or whether they were transformed to metabolites. The novel tool of position-specific labeling enables to trace molecule atoms separately and thus to determine the cleavage of molecules - a prerequisite for metabolic tracing. Position-specific labeling of LMWOS and quantification of 13CO2 and 13C in bulk soil enabled following the basic metabolic pathways of soil microorganisms. However, only the combination of position-specific 13C labeling with compound-specific isotope analysis of microbial biomarkers and metabolites allowed 1) tracing specific anabolic pathways in diverse microbial communities in soils and 2) identification of specific pathways of individual functional microbial groups. So, these are the prerequisites for soil fluxomics. Our studies combining position-specific labeled glucose with amino

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  15. Comparing three methods of NEE-flux partitioning from the same grassland ecosystem: the 13C, 18O isotope approach and using simulated Ecosystem respiration

    NASA Astrophysics Data System (ADS)

    Siegwolf, R.; Bantelmann, E.; Saurer, M.; Eugster, W.; Buchmann, N.

    2007-12-01

    As a change in the global climate occurs with increasing temperatures, the Carbon exchange processes of terrestrial ecosystems will change as well. However, it is difficult to quantify the degree to what ecosystem respiration will change relative to the CO2 uptake by photosynthesis. To estimate the carbon sequestration potential of terrestrial vegetation cover it is essential to know both fluxes: ecosystem respiration and the carbon uptake by the vegetation cover. Therefore the net ecosystem exchange of CO2 (NEE) was measured with the eddy covariance method and separated into assimilation and respiration flux. We applied three different approaches, 1) the conventional method, applying the nighttime relationship between soil temperature and NEE for calculating the respiration flux during the day, 2) the use of stable carbon and 3) oxygen isotopes. We compared the results of the three partitioning exercises for a temperate grassland ecosystem in the pre-Alps of Switzerland for four days in June 2004. The assimilation flux derived with the conventional NEE partitioning approach, was best represented at low PAR and low temperatures, in the morning between 5 and 9 am. With increasing temperature and PAR the assimilation for the whole canopy was underestimated. For partitioning NEE via 18O approach, correlations of temperature and radiation with assimilation and respiration flux were significantly higher for the partitioning approach with 18O than for the 13C NEE partitioning. A sensitivity analysis showed the importance of an accurate determination of the equilibrium term θ between CO2 and leaf water δ18O for the NEE partitioning with 18O. For using 13C to partition NEE, the correct magnitude of the 13C fractionation and for the respiration term is essential. The analysis of the data showed that for low light and low morning temperatures the conventional method delivers reasonably good results. When the temperatures exceeded 21°C the isotope approach provided the

  16. GC-MS determination of ratios of stable-isotope labelled to natural urea using [13C15N2]urea for studying urea kinetics in serum and as a means to validate routine methods for the quantitative assay of urea in dialysate.

    PubMed

    Wolthers, B G; Tepper, T; Withag, A; Nagel, G T; de Haan, T H; van Leeuwen, J J; Stegeman, C A; Huisman, R M

    1994-02-01

    A GC-MS determination of urea in serum or spent dialysate is described, using 13C15N2-labelled urea and assaying the area ratio of labelled to natural urea by mass fragmentographic monitoring of fragments m/e 153 and 156, after its eventual conversion into the trimethylsilylether-derivative of 2-hydroxypyrimidine. The procedure can be successfully applied in the follow-up of the disappearance of labelled urea in serum after intravenous injection in man, enabling kinetic parameters of urea to be established, e.g. for purposes of studying the effectiveness of dialysis procedures. Furthermore the method can be used for validation of routine methods for measuring urea in other fluids, in particular dialysate. Examples are given of both applications of the GC-MS method described. PMID:8033352

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

    PubMed

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

    2015-01-01

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

  18. Stable isotope signals of eutrophication in Baltic Sea sediments

    NASA Astrophysics Data System (ADS)

    Voss, Maren; Larsen, Birger; Leivuori, Mirja; Vallius, Henry

    2000-07-01

    Increasing δ15N and δ13C values in coastal Baltic marine sediments are evaluated as indicator of changes in the trophic status of the ecosystem. The influence of eutrophication on the δ15N values was found to be so dominant that it even overprints the usually observed mixing gradient from terrestrial (low isotope values) to the marine environment (high isotope values). A distinct gradient in stable nitrogen isotope values from eutrophic coastal areas to open more oligotrophic waters in the central Baltic Sea and Gulf of Bothnia was found. Our data show high δ15N values in surface sediments: 13‰ in the Oder Lagoon and the Pomeranian Bight, over 9‰ in the Gulf of Riga (Daugava River), 7‰ in the inner Gulf of Finland (Neva River), 6.5‰ in the Curonian Lagoon (Nemunas River), and 5.7‰ in the Gdansk Deep (Vistula River). In the Baltic Sea Proper, significantly lower δ15N values of 3-5‰ are found. A decrease in δ15N values with depth/age of the sediment was indicated in some cores that were analyzed down to 15-40 cm depth in 1-cm steps. There is a great overall difference between pre-industrial δ15N values in coastal sediments and recent ones of 2.3-10‰. As explanations for this increase are suggested, elevated nutrient δ15N values of waste water in combination with fractionation processes like nutrient uptake by phytoplankton and denitrification and nitrification processes in rivers discharging into the coastal water. Delta 13C values in sediment surfaces off the river estuaries primarily indicate differences between the inorganic carbon signatures of the rivers. However, since the δ13C values also decrease downcore, we contribute this change to increased primary production caused by the enhanced nutrient load. Since both stable isotope values in sediments ( δ13C and δ15N) correlate downcore, this strongly suggests that the anthropogenic nutrient loads in the rivers might be the reason for the changes of stable isotope values.

  19. The biodegradation of fluoranthene as monitored using stable carbon isotopes

    SciTech Connect

    Trust, B.A.; Mueller, J.G.; Coffin, R.B.; Cifuentes, L.A.

    1995-12-31

    The measurement of stable isotope ratios of carbon ({delta}{sup 13}C values) was investigated as a viable technique to monitor the intrinsic bioremediation of polycyclic aromatic hydrocarbons (PAHs). Biometer flask experiments were conducted in which the bacterium, Sphingomonas paucimobilis, designated EPA505, was grown on fluoranthene. During growth of EPA505 on fluoranthene, bacterial biomass, respired CO{sub 2}, and dissolved organic carbon (DOC), as well as fluoranthene, were sampled over 8 days. The concentrations and {delta}{sup 13}C values of each of these carbon pools were determined. The concentration of fluoranthene decreased from 12.1 {+-} 2.0 (n = 2) to 3.0 {+-} 0.9 (n = 2) mg C per flask over 188 h, and CO{sub 2} increased from undetectable levels to 7.1 {+-} 0.3 (n = 4) mg C per flask. A total of 55.5% mineralization resulted. DOC concentrations remained fairly constant with time, averaging 2.2 to 3.6 mg C per flask. The {delta}{sup 13}C value of fluoranthene remained constant over the course of the experiment, averaging {minus}24.5 {+-} 0.2{per_thousand} (n = 8). Bacterial nucleic acids and respired CO{sub 2} took on {delta}{sup 13}C values similar to those of fluoranthene within 47 h, measuring {minus}22.6 and {minus}24.3{per_thousand}, respectively.

  20. The stable isotope fingerprinting technique for agricultural pesticide

    NASA Astrophysics Data System (ADS)

    Suto, N.; Kawashima, H.

    2014-12-01

    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

  1. 12C/13C kinetic isotope effects in the reactions of CH4 with OH and Cl

    NASA Astrophysics Data System (ADS)

    Gupta, Mohan L.; McGrath, M. P.; Cicerone, R. J.; Rowland, F. S.; Wolfsberg, M.

    1997-11-01

    In qualitative agreement with previous MP2 level calculations of the 12C/13C kinetic isotope effects (KIEs) for H-abstraction of CH4 by OH and Cl, higher level calculations yield KIEs at 300 K that differ from the corresponding experimental values, but in different directions. At QCISD(T)/6-311+G(2df,p), the theoretical KIE for CH4+Cl is 32‰ less than the measured value, while for CH4+OH, the theoretical KIE is greater than the measured value, but only by 5‰. Noticeable differences in atmospheric model simulation studies can occur if the measured KIEs are replaced by the analogous theoretical values. For example, the effect of carbon isotopic fractionation from the CH4 + Cl reaction on stratospheric δ13CH4 will be significantly lower than that obtained by Bergamaschi et al. [1996]. It is suggested, for the CH4+OH reaction and especially for the CH4+Cl reaction, that additional KIE measurements are needed.

  2. Investigation of amino acid δ 13C signatures in bone collagen to reconstruct human palaeodiets using liquid chromatography-isotope ratio mass spectrometry

    NASA Astrophysics Data System (ADS)

    Choy, Kyungcheol; Smith, Colin I.; Fuller, Benjamin T.; Richards, Michael P.

    2010-11-01

    This research presents the individual amino acid δ 13C values in bone collagen of humans ( n = 9) and animals ( n = 27) from two prehistoric shell midden sites in Korea. We obtained complete baseline separation of 16 of the 18 amino acids found in bone collagen by using liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). The isotopic results reveal that the humans and animals in the two sites had similar patterns in essential amino acids (EAAs) and non-essential amino acids (NEAAs). The EAA and NEAA δ 13C values in humans are intermediate between those in marine and terrestrial animals. However, the threonine δ 13C values in humans and animals measured in this study are more highly enriched than those of other amino acids. At both sites, all amino acids in marine animals are 13C-enriched relative to those of the terrestrial animals. The isotopic evidence suggests that the Tongsamdong human had EAAs and NEAAs from marine food resources, while the Nukdo humans mainly had EAAs from terrestrial food resources but obtained NEAAs from both terrestrial and marine resources. The δ 13C isotopic differences in amino acids between marine and terrestrial animals were the largest for glycine (NEAA) and histidine (EAA) and the smallest for tyrosine (NEAA) and phenylalanine (EAA). In addition, threonine among the EAAs also had a large difference (˜8‰) in δ 13C values between marine and terrestrial animals, and has the potential to be used as an isotopic marker in palaeodietary studies. Threonine δ 13C values were used in conjunction with the established Δ 13C Glycine-phenylalanine values and produced three distinct dietary groups (terrestrial, omnivorous, and marine). In addition, threonine δ 13C values and Δ 13C Serine-phenylalanine values were discovered to separate between two dietary groups (terrestrial vs. marine), and these δ 13C values may provide a potential new indicator for investigating the distinction between marine and terrestrial protein

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

    USGS Publications Warehouse

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

    2006-01-01

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

  4. Stable Isotope Enrichment Capabilities at ORNL

    SciTech Connect

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

    2013-01-01

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

  5. Experimental Evidence for Heavy-Atom Tunneling in the Ring-Opening of Cyclopropylcarbinyl Radical from Intramolecular 12C/13C Kinetic Isotope Effects

    PubMed Central

    Gonzalez-James, Ollie M.; Zhang, Xue; Datta, Ayan; Hrovat, David A.; Borden, Weston Thatcher; Singleton, Daniel A.

    2010-01-01

    The intramolecular 13C kinetic isotope effects for the ring-opening of cyclopropylcarbinyl radical were determined over a broad temperature range. The observed isotope effects are unprecedentedly large, ranging from 1.062 at 80 °C to 1.163 at −100 °C. Semi-classical calculations employing canonical variational transition state theory drastically underpredict the observed isotope effects, but the predicted isotope effects including tunneling by a small-curvature tunneling model match well with experiment. These results and a curvature in the Arrhenius plot of the isotope effects support the recently predicted importance of heavy-atom tunneling in cyclopropylcarbinyl ring-opening. PMID:20722415

  6. Experimental evidence for heavy-atom tunneling in the ring-opening of cyclopropylcarbinyl radical from intramolecular 12C/13C kinetic isotope effects.

    PubMed

    Gonzalez-James, Ollie M; Zhang, Xue; Datta, Ayan; Hrovat, David A; Borden, Weston Thatcher; Singleton, Daniel A

    2010-09-15

    The intramolecular (13)C kinetic isotope effects for the ring-opening of cyclopropylcarbinyl radical were determined over a broad temperature range. The observed isotope effects are unprecedentedly large, ranging from 1.062 at 80 degrees C to 1.163 at -100 degrees C. Semiclassical calculations employing canonical variational transition-state theory drastically underpredict the observed isotope effects, but the predicted isotope effects including tunneling by a small-curvature tunneling model match well with experiment. These results and a curvature in the Arrhenius plot of the isotope effects support the recently predicted importance of heavy-atom tunneling in cyclopropylcarbinyl ring-opening. PMID:20722415

  7. The Stable Isotopic Composition of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Yakir, D.

    2003-12-01

    in nature ( Thiemens, 1999; see Chapter 4.06, and of triple stable isotopes in geochemistry (e.g., Blunier et al., 2002; Luz et al., 1999; Luz and Barkan, 2000) greatly extended the potential of stable isotope applications.The chemical and isotopic composition of the atmosphere has drawn particular attention in climate-related research both because it is the most accessible component in the tightly coupled land-ocean-atmosphere system, and because the chemical composition of the atmosphere influences climate, particularly via the concentrations of the radiatively active greenhouse gases, such as CO2, O3, CH4, N2O, and water vapor. Information obtained by measurements of the atmospheric concentration of these gases alone is limited; the additional measurements of the stable isotopic composition provide information that cannot be obtained otherwise. Isotopic fractionations during chemical, physical, and biological process in the ocean, land, and the atmosphere result in unique natural labels. Tracing these labels in time and space allows us both to identify specific fluxes of these gases, and to gain insights into the processes influencing the observed fluxes. Quantitative use of 18O and 13C in CO2 must rely on precise observations, on experimentation addressing the isotope effects underlying these observations, and on modeling that tests basic assumptions and extends applications beyond our measuring capabilities. Progress is still needed on all of these fronts. But the importance of this still developing science of stable isotopes in environmental research is indisputable.

  8. Stable isotope labeling methods for DNA.

    PubMed

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

    2016-08-01

    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. PMID:27573183

  9. BOREAS TE-5 CO2 Concentration and Stable Isotope Composition

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    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).

  10. Magnesium stable isotope ecology using mammal tooth enamel

    PubMed Central

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

    2015-01-01

    Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (δ13C) 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 (δ44Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (δ26Mg) 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 δ26Mg, δ13C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that δ26Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this 26Mg enrichment up the trophic chain is due to a 26Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using δ26Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel δ26Mg composition remain to be explored but, in the future, multiproxy approaches would permit a substantial refinement of dietary behaviors or enable accurate trophic reconstruction despite specimen-limited sampling, as is often the case for fossil assemblages. PMID:25535375

  11. Magnesium stable isotope ecology using mammal tooth enamel.

    PubMed

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

    2015-01-13

    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. PMID:25535375

  12. Magnesium stable isotope ecology using mammal tooth enamel

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (δ13C) 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 (δ44Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (δ26Mg) 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 δ26Mg, δ13C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that δ26Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this 26Mg enrichment up the trophic chain is due to a 26Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using δ26Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel δ26Mg 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.

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

    PubMed

    Walter, W D; Leslie, D M

    2009-07-01

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

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

    PubMed

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

    2015-12-01

    A critical component of the biogeochemical cycle of mercury (Hg) is the transformation of inorganic Hg to neurotoxic monomethylmercury (CH3Hg). Humans are exposed to CH3Hg by consuming marine fish, yet the origin of CH3Hg in fish is a topic of debate. The carbon stable isotopic composition (δ(13)C) embedded in the methyl group of CH3Hg remains unexplored. This new isotopic information at the molecular level is thought to represent a new proxy to trace the carbon source at the origin of CH3Hg. Here, we present a compound-specific stable isotope analysis (CSIA) technique for the determination of the δ(13)C value of CH3Hg in biological samples by gas chromatography combustion isotope ratio mass spectrometry analysis (GC-C-IRMS). The method consists first of calibrating a CH3Hg standard solution for δ(13)C CSIA. This was achieved by comparing three independent approaches consisting of the derivatization and halogenation of the CH3Hg standard solution. The determination of δ(13)C(CH3Hg) values on natural biological samples was performed by combining a CH3Hg selective extraction, purification, and halogenation followed by GC-C-IRMS analysis. Reference δ(13)C values were established for a tuna fish certified material (ERM-CE464) originating from the Adriatic Sea (δ(13)C(CH3Hg) = -22.1 ± 1.5‰, ± 2 SD). This value is similar to the δ(13)C value of marine algal-derived particulate organic carbon (δ(13)CPOC = -21‰). PMID:26511394

  15. Applications of stable isotopes in clinical pharmacology

    PubMed Central

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

    2011-01-01

    This review aims to present an overview of the application of stable isotope technology in clinical pharmacology. Three main categories of stable isotope technology can be distinguished in clinical pharmacology. Firstly, it is applied in the assessment of drug pharmacology to determine the pharmacokinetic profile or mode of action of a drug substance. Secondly, stable isotopes may be used for the assessment of drug products or drug delivery systems by determination of parameters such as the bioavailability or the release profile. Thirdly, patients may be assessed in relation to patient-specific drug treatment; this concept is often called personalized medicine. In this article, the application of stable isotope technology in the aforementioned three areas is reviewed, with emphasis on developments over the past 25 years. The applications are illustrated with examples from clinical studies in humans. PMID:21801197

  16. Stable Isotope Resolved Metabolomics Studies in Ex Vivo TIssue Slices

    PubMed Central

    Fan, Teresa W-M.; Lane, Andrew N.; Higashi, Richard M.

    2016-01-01

    An important component of this methodology is to assess the role of the tumor microenvironment on tumor growth and survival. To tackle this problem, we have adapted the original approach of Warburg 1, by combining thin tissue slices with Stable Isotope Resolved Metabolomics (SIRM) to determine detailed metabolic activity of human tissues. SIRM enables the tracing of metabolic transformations of source molecules such as glucose or glutamine over defined time periods, and is a requirement for detailed pathway tracing and flux analysis. In our approach, we maintain freshly resected tissue slices (both cancerous and non- cancerous from the same organ of the same subject) in cell culture media, and treat with appropriate stable isotope-enriched nutrients, e.g. 13C6-glucose or 13C5, 15N2 -glutamine. These slices are viable for at least 24 h, and make it possible to eliminate systemic influence on the target tissue metabolism while maintaining the original 3D cellular architecture. It is therefore an excellent pre-clinical platform for assessing the effect of therapeutic agents on target tissue metabolism and their therapeutic efficacy on individual patients 2,3. PMID:27158639

  17. Detection of adulteration in honey samples added various sugar syrups with 13C/12C isotope ratio analysis method.

    PubMed

    Tosun, Murat

    2013-06-01

    Honey can be adulterated in various ways. One of the adulteration methods is the addition of different sugar syrups during or after honey production. Starch-based sugar syrups, high fructose corn syrup (HFCS), glucose syrup (GS) and saccharose syrups (SS), which are produced from beet or canes, can be used for adulterating honey. In this study, adulterated honey samples were prepared with the addition of HFCS, GS and SS (beet sugar) at a ratio of 0%, 10%, 20%, 40% and 50% by weight. (13)C/(12)C analysis was conducted on these adulterated honey samples using an isotope ratio mass spectrometer in combination with an elemental analyser (EA-IRMS). As a result, adulteration using C(4) sugar syrups (HFCS and GS) could be detected to a certain extent while adulteration of honey using C(3) sugar syrups (beet sugar) could not be detected. Adulteration by using SS (beet sugar) still has a serious detection problem, especially in countries in which beet is used in manufacturing sugar. For this reason, practice and analysis methods are needed to meet this deficit and to detect the adulterations precisely in the studies that will be conducted. PMID:23411291

  18. Stable isotope variations in benthic filter feeders across a large depth gradient on the continental shelf

    NASA Astrophysics Data System (ADS)

    Nerot, Caroline; Lorrain, Anne; Grall, Jacques; Gillikin, David P.; Munaron, Jean-Marie; Le Bris, Hervé; Paulet, Yves-Marie

    2012-01-01

    Spatial variations in carbon and nitrogen stable isotopes13C and δ 15N) of benthic filter feeders were investigated on an inshore-offshore gradient (0-250 km) along the continental shelf of the northern Bay of Biscay (NE Atlantic Ocean). δ 13C and δ 15N values were measured in muscle tissues of four filter-feeding mollusc species (epifaunal: Pecten maximus, Aequipecten opercularis; infaunal: Glycymeris glycymeris, Venus casina) and in benthic particulate organic matter along a corresponding water-depth gradient from 6 to 220 m. All four species showed a decreasing pattern of muscle δ 13C and δ 15N values with increasing depth. At the Ushant front (˜130 m water depth), where there is a decrease in both bottom water chlorophyll a and suspended particulate matter, muscle δ 13C and δ 15N values decreased in all species. Although δ 13C values of infaunal clams initially decreased at 30 m depth, δ 13C values of epifaunal scallops decreased around 120 m depth, far below the expected depth reduction in microphytobenthic production suggesting that carbon isotopes might not simply track microphytobenthic utilization. The difference between infaunal and epifaunal bivalve stable isotope values may reflect differences in feeding strategies. Muscle δ 15N values at the deepest stations (˜2‰) were lower than expected considering the typical trophic enrichment value of 3-4‰ between prey and consumers. These low δ 15N values may result from low metabolic rates and suggest the classic trophic enrichment may not hold true in species inhabiting deep waters. Stable isotopes in benthic filter feeders can reveal much information regarding their ecology and environment, but are not straightforward recorders of stable isotope baseline variations as is often assumed.

  19. RAPID AND PRECISE METHOD FOR MEASURING STABLE CARBON ISOTOPE RATIOS OF DISSOLVED INORGANIC CARBON

    EPA Science Inventory

    We describe a method for rapid preparation, concentration and stable isotopic analysis of dissolved inorganic carbon (d13C-DIC). Liberation of CO2 was accomplished by placing 100 ?l phosphoric acid and 0.9 ml water in an evacuated 1.7-ml gas chromatography (GC) injection vial. Fo...

  20. Stable Carbon and Oxygen Isotope Ratios of Otoliths Differentiate Winter Flounder (Pseudopleuonectes americanus) Habitats

    EPA Science Inventory

    Stable carbon (13C) and oxygen (18O) isotope ratios were measured in otoliths of juvenile winter flounder (Pseudopleuronectes americanus) collected from 18 nursery areas along the coast of Rhode Island, USA. Samples were obtained during June and July of 2002 from locations tha...

  1. Patterns in stable isotope ratios of particulate material from the eastern US continental shelf

    EPA Science Inventory

    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...

  2. Diet of spotted bats (Euderma maculatum) in Arizona as indicated by fecal analysis and stable isotopes

    EPA Science Inventory

    We assessed diet of spotted bats (Euderma maculatum (J.A. Allen, 1891)) by visual analysis of bat feces and stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of bat feces, wing, hair, and insect prey. We collected 33 fecal samples from spotted bats and trapped 3755 insect...

  3. FATTY ACID STABLE ISOTOPE INDICATORS OF MICROBIAL CARBON SOURCE IN TROPICAL SOILS

    EPA Science Inventory

    The soil microbial community plays an important role in tropical ecosystem functioning because of its importance in the soil organic matter (SOM) cycle. We have measured the stable carbon isotopic ratio (delta13C) of individual phospholipid fatty acids (PLFAs) in a variety of tr...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  5. Analysis of stable isotopes in fish mucus during a controlled diet switch

    EPA Science Inventory

    We have used a controlled diet switch in steelhead trout (Oncorhynchus mykiss) at the Oregon Hatchery Research Center to study the time rates of changes in stable isotopes of carbon and nitrogen (13C and 15N) in epidermal mucus, a rapidly responding “tissue.” Because of the ra...

  6. Quantifying intra-population variability in stable isotope data for spotted seatrout (cynoscion nebulosus)

    EPA Science Inventory

    Stable isotope (SI) values of carbon (δ13C) and nitrogen (δ15N) are useful for determining the trophic connectivity between species within an ecosystem, but interpretation of these data involves important assumptions about sources of intrapopulation variability. We compared i...

  7. Stable isotope analysis of fish mucus during a controlled diet switch

    EPA Science Inventory

    We have used a controlled diet switch in steelhead trout (Oncorhynchus mykiss) at the Oregon Hatchery Research Center to study the time rates of changes in stable isotopes of carbon and nitrogen (13C and 15N) in epidermal mucus, a rapidly responding “tissue.” Because of the ra...

  8. Experimental Evaluation of Stable Isotope Fractionation in Fish Muscle and Otoliths

    EPA Science Inventory

    We investigated an unresolved question in the use of stable isotopes to determine diet and trophic position of fish using both muscle and otoliths. We determined: i) the degree of fractionation of δ13C and δ15N between diet and muscle, and assessed if fractionation was consistent...

  9. 13C/12C and 15N/14N Isotope Analysis to Characterize Natural Degradation of Atrazine: Evidence from Parent and Daughter Compound Values

    NASA Astrophysics Data System (ADS)

    Elsner, Martin; Meyer, Armin

    2013-04-01

    The mobile and still herbicidal metabolites desethylatrazine (DEA) and desisopropylatrazine (DIA) are frequently detected together with its parent compound atrazine (Atz) in the aquatic environment. Interpretation of their transformation state is often difficult with current methods, which are mainly measuring concentrations. Alternatively, compound specific isotope analyses (CSIA) has become a novel tool to detect degradation processes of contaminants in groundwater. The aim of our study was to investigate on the lab scale 13C/12C and 15N/14N isotope trends in parent and daughter compounds associated with different degradation scenarios of atrazine likely to occur in the environment. Thus atrazine was dealkylated with (i) permanganate and (ii) the bacterium Rhodococcus sp. NI86/21. In both transformations, 13C/12C ratios of atrazine increased strongly (epsilon carbon/permanganate = -4.6 ± 0.6 ‰ and epsilon carbon/Rhodoccoccus = -3.8 ± 0.2 ‰) whereas nitrogen isotope fractionation was small. 13C/12C ratios of DEA showed the following trends. (i) When DEA was formed as only product (Atz + permanganate) 13C/12C remained constant, close to the initial value of Atz. (ii) When DEA was formed together with deisopropylatrazine (biodegradation of Atz) 13C/12C increased, but only within 2‰. (iii) When DEA and DIA was further biodegraded, 13C/12C increased for both metabolites up to 9‰. Thus strong enrichment of 13C/12C in the metabolites in comparison to Atz can give strong testimony for further breakdown of the metabolite.

  10. The Impact of Sewage Discharge in a Marine Embayment: A Stable Isotope Reconnaissance

    NASA Astrophysics Data System (ADS)

    Waldron, S.; Tatner, P.; Jack, I.; Arnott, C.

    2001-01-01

    Stable isotope analyses, δ 13C and δ 15N, of sewage tolerant benthic invertebrates seaward of a sewage effluent discharged in a marine embayment, the Firth of Forth, East Scotland, suggest that the polychaete worm Nereis virens is a suitable species for identifying biological assimilation of sewage derived organic matter. The sewage isotopic signal is not strongly recorded in the sediment due to the combined action of tidal movement, wind-induced wave action and benthic invertebrate grazing of particulate matter on the sea-bed. δ 13C of the plankton is significantly different from the effluent, but δ 15N is not which precludes its use as a trace.

  11. Enzymatic synthesis and RNA interference of nucleosides incorporating stable isotopes into a base moiety.

    PubMed

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

    2015-10-15

    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. PMID:26404411

  12. A User-Friendly 13C Isotope Discrimination Method for Root Studies with Rice and C4 Weeds in Field Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sustainable weed control is a continuing challenge in rice production in the U.S. Some rice cultivars can provide significant levels of barnyardgrass (Echinochloa crus-galli) suppression, much of which is thought to occur below the soil surface. This presentation describes a simple 13C isotope dep...

  13. Fire effects on stable isotopes in a Sierran forested watershed.

    PubMed

    Saito, Laurel; Miller, Wally W; Johnson, Dale W; Qualls, Robert G; Provencher, Louis; Carroll, Erin; Szameitat, Peter

    2007-01-01

    This study tested the hypothesis that stable C and N isotope values in surface soil and litter would be increased by fire due to volatilization of lighter isotopes. The hypothesis was tested by: (1) performing experimental laboratory burns of organic and mineral soil materials from a watershed at combinations of temperature ranging 100 to 600 degrees C and duration ranging from 1 to 60 min; (2) testing field samples of upland soils before, shortly after, and 1 yr following a wildfire in the same watershed; and (3) testing field soil samples from a down-gradient ash/sediment depositional area in a riparian zone following a runoff event after the wildfire. Muffle furnace results indicated the most effective temperature range for using stable isotopes for tracing fire impacts is 200 to 400 degrees C because lower burn temperatures may not produce strong isotopic shifts, and at temperatures>or=600 degrees C, N and C content of residual material is too low. Analyses of field soil samples were inconclusive: there was a slightly significant effect of the wildfire on delta15N values in upland watershed analyses 1 yr postburn, while riparian zone analyses results indicated that delta13C values significantly decreased approximately 0.71 per thousand over a 9 mo post-fire period (p=0.015), and ash/sediment layer delta13C values were approximately 0.65 per thousand higher than those in the A horizon. The lack of field confirmation may have been due to overall wildfire burn temperatures being <200 degrees C and/or microbial recovery and vegetative growth in the field. Thus, the muffle furnace experiment supported the hypothesis, but it is as yet unconfirmed by actual wildfire field data. PMID:17215216

  14. The utilization of stable isotope analysis for the estimation of the geographic origins of unidentified cadavers.

    PubMed

    McLean, Stuart J; Ikegaya, Hiroshi; Saukko, Pekka J; Zheng, Huang Yung; Itoh, Kyoko; Fushiki, Shinji

    2014-12-01

    The number of unidentified cadavers is increasing worldwide and the effective methods which reveal their geographic origin are not well known. This study reports on the utilization of δ(18)O, δ(13)C, δ(2)H and δ(15)N ratios gained through stable isotope analysis of urine samples collected from eight locations: Chiba, Japan; Fuzhou, China; and Denpasar, Indonesia in our pilot study with data from healthy volunteers from five further locations from healthy volunteers: Melbourne and Perth, Australia; Qingdao, China; Turku, Finland and Oklahoma, USA. This study posits that the utilization of δ(18)O and δ(2)H is more feasible than δ(13)C and δ(15)N stable isotope ratios in differentiating or estimating the origin of human samples. Secondly, this study demonstrated that the δ(18)O and δ(2)H stable isotope ratios of urine samples from eight locations differed significantly. PMID:25447173

  15. Stable isotope composition of Earth's large lakes

    NASA Astrophysics Data System (ADS)

    Jasechko, S.; Gibson, J. J.; YI, Y.; Birks, S. J.; Sharp, Z. D.

    2011-12-01

    Lakes cover about three percent of Earth's continental area. Large lakes can significantly influence lake shore and regional climates by increasing specific humidity during evaporation and by moderating air temperatures. Stable isotopes of oxygen and hydrogen can be used to quantify lake evaporation, providing a supplementary and often cost-advantageous alternative to conventional hydrologic approaches that require over lake monitoring. Further, stable isotopes in lake sediments are an established tool in paleolimnology; however, interpreting changes to a lake's past isotope composition requires a comprehensive understanding of contemporary controls. Here, δ18O and δ2H values of water in modern lakes exceeding roughly five hundred square kilometres are compiled (n > 35). Voluminous and seasonally mixed lakes - such as the North American Great Lakes - have the most homogenous stable isotope compositions, while perennially-stratified and shallow lakes show greater variability. A rudimentary stable isotope mass balance is used to assess evaporation fluxes from large lakes on Earth. The approach taken simultaneously constrains evaporation outputs for both oxygen and hydrogen stable isotopes by accounting for lake effects on the overlying atmosphere. Model development highlights important considerations such as isotopic stratification (Tanganyika), disequilibrium isotopic mass balances (Baikal), and non-steady hydrologic balances. Further, the isotope composition of Earth's continental surface water reservoir is calculated. This value - weighted to volume - is δ18O = -7.5±1.7 per mille relative to standard mean ocean water. The compiled data may be a useful tracer of continental evaporate in global atmospheric water cycle studies and could be coupled to climate models capable of incorporating oxygen-18 and deuterium tracers to improve or validate calculations of lake effects on regional water cycling.

  16. Stable Isotope Mapping of Alaskan Grasses and Marijuana

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    The spatial variation of isotope signatures in organic material is a useful forensic tool, particularly when applied to the task of tracking the production and distribution of plant-derived illicit drugs. In order to identify the likely grow-locations of drugs such as marijuana from unknown locations (i.e., confiscated during trafficking), base isotope maps are needed that include measurements of plants from known grow-locations. This task is logistically challenging in remote, large regions such as Alaska. We are therefore investigating the potential of supplementing our base (marijuana) isotope maps with data derived from other plants from known locations and with greater spatial coverage in Alaska. These currently include >150 samples of modern C3 grasses (Poaceae) as well as marijuana samples (n = 18) from known grow-locations across the state. We conducted oxygen, carbon and nitrogen stable isotope analyses of marijuana and grasses (Poaceae). Poaceae samples were obtained from the University of Alaska Fairbanks (UAF) Museum of the North herbarium collection, originally collected by field botanists from around Alaska. Results indicate that the oxygen isotopic composition of these grasses range from 10‰ to 30‰, and broadly mirror the spatial pattern of water isotopes in Alaska. Our marijuana samples were confiscated around the state of Alaska and supplied to us by the UAF Police Department. 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

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

    PubMed

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

    2011-04-13

    A stable isotope dilution assay (SIDA) for the Alternaria mycotoxin tenuazonic acid was developed. Therefore, [(13)C(6),(15)N]-tenuazonic acid was synthesized from [(13)C(6),(15)N]-isoleucine by Dieckmann intramolecular cyclization after acetoacetylation with diketene. The synthesized [(13)C(6),(15)N]-tenuazonic acid was used as the internal standard for determination of tenuazonic acid in tomato products by liquid chromatography tandem mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine. Method validation revealed a limit of detection of 0.1 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). PMID:21370870

  18. Performance of human mass balance studies with stable isotope-labeled drug and continuous flow-isotope ratio mass spectrometry: a progress report.

    PubMed

    Browne, T R; Szabo, G K; Ajami, A; Browne, D G

    1998-04-01

    We propose performing human mass balance studies by administering stable isotope labeled (13C or 15N) drug and quantitating excess (above background) 13C or 15N in urine, serum, and feces by continuous flow-isotope ratio mass spectrometry (CF-IRMS). Theoretical calculations and empirical data (dynamic range, linearity, sensitivity, precision, accuracy) are presented to establish that commercially available CF-IRMS instruments can quantitate stable isotope labeled (one or two 15N or 13C labels) drug concentrations of 1.0 microg/mL or greater in urine, serum (15N), or feces. More than two 13C labels may be necessary to quantitate 1.0 microg/mL of drug in serum. Three volunteers received 650 mg of 15N13C2-acetaminophen, and urine was collected for 72 hours. Percent of administered label recovered in urine from the three subjects was 97.4, 78.9, and 95.4 for 13C and 90.3, 77.0, and 90.6 for 15N. Fecal recovery of label for one subject was 0.9% (13C2) and 1.1% (15N). Serum pharmacokinetic values obtained by counting 13C or 15N in one subject were as expected for acetaminophen. This method appears to be promising, and further validation is ongoing. PMID:9590457

  19. Hitting the moving target: modelling ontogenetic shifts with stable isotopes reveals the importance of isotopic turnover.

    PubMed

    Hertz, Eric; Trudel, Marc; El-Sabaawi, Rana; Tucker, Strahan; Dower, John F; Beacham, Terry D; Edwards, Andrew M; Mazumder, Asit

    2016-05-01

    Ontogenetic niche shifts are widely prevalent in nature and are important in shaping the structure and dynamics of ecosystems. Stable isotope analysis is a powerful tool to assess these shifts, with δ(15) N providing a measure of trophic level and δ(13) C a measure of energy source. Previous applications of stable isotopes to study ontogenetic niche shifts have not considered the appreciable time lag between diet and consumer tissue associated with isotopic turnover. These time lags introduce significant complexity into field studies of ontogenetic niche shifts. Juvenile Chinook salmon (Oncorhynchus tshawytscha) migrate from freshwater to marine ecosystems and shift their diet from feeding primarily on invertebrates to feeding primarily on fish. This dual ontogenetic habitat and diet shift, in addition to the long time lag associated with isotopic turnover, suggests that there is potential for a disconnect between the prey sources that juvenile salmon are consuming, and the inferred prey sources from stable isotopes. We developed a model that considered ontogenetic niche shifts and time lags associated with isotopic turnover, and compared this 'ontogeny' model to one that considered only isotopic turnover. We used a Bayesian framework to explicitly account for parameter uncertainty. Data showed overwhelming support for the ontogeny model relative to the isotopic turnover model. Estimated variables from best model fits indicate that the ontogeny model predicts a much greater reliance on fish prey than does the stomach content data. Overall, we found that this method of quantifying ontogenetic niche shifts effectively accounted for both isotopic turnover and ontogenetic diet shifts; a finding that could be widely applicable to a variety of systems. PMID:26880007

  20. Stable isotopes of C and S as indicators of habitat use by fish in small oregon Coast range streams

    EPA Science Inventory

    We are using stable isotopes of C, N, O and S (H planned) to study the ecology of coho salmon in streams of the Oregon Coast Range. We have found isotopes of C and, surprisingly, S to be very useful in discriminating rearing habitats in our small streams. We found 13C values ...

  1. Determination of primary and secondary sources of organic acids and carbonaceous aerosols using stable carbon isotopes

    NASA Astrophysics Data System (ADS)

    Fisseha, Rebeka; Saurer, Matthias; Jäggi, Maya; Siegwolf, Rolf T. W.; Dommen, Josef; Szidat, Sönke; Samburova, Vera; Baltensperger, Urs

    Stable carbon isotope ratio ( δ13C) data can provide important information regarding the sources and the processing of atmospheric organic carbon species. Formic, acetic and oxalic acid were collected from Zurich city in August-September 2002 and March 2003 in the gas and aerosol phase, and the corresponding δ13C analysis was performed using a wet oxidation method followed by isotope ratio mass spectrometry. In August, the δ13C values of gas phase formic acid showed a significant correlation with ozone (coefficient of determination ( r2) = 0.63) due to the kinetic isotope effect (KIE). This indicates the presence of secondary sources (i.e. production of organic acids in the atmosphere) in addition to direct emission. In March, both gaseous formic and acetic acid exhibited similar δ13C values and did not show any correlation with ozone, indicating a predominantly primary origin. Even though oxalic acid is mainly produced by secondary processes, the δ13C value of particulate oxalic acid was not depleted and did not show any correlation with ozone, which may be due to the enrichment of 13C during the gas - aerosol partitioning. The concentrations and δ13C values of the different aerosol fractions (water soluble organic carbon, water insoluble organic carbon, carbonate and black carbon) collected during the same period were also determined. Water soluble organic carbon (WSOC) contributed about 60% to the total carbon and was enriched in 13C compared to other fractions indicating a possible effect of gas - aerosol partitioning on δ13C of carbonaceous aerosols. The carbonate fraction in general was very low (3% of the total carbon).

  2. Abundance Anomaly of the 13C Isotopic Species of c-C3H2 in the Low-mass Star Formation Region L1527

    NASA Astrophysics Data System (ADS)

    Yoshida, Kento; Sakai, Nami; Tokudome, Tomoya; López-Sepulcre, Ana; Watanabe, Yoshimasa; Takano, Shuro; Lefloch, Bertrand; Ceccarelli, Cecilia; Bachiller, Rafael; Caux, Emmanuel; Vastel, Charlotte; Yamamoto, Satoshi

    2015-07-01

    The rotational spectral lines of c-C3H2 and two kinds of the 13C isotopic species, c-{}13{{CCCH}}2 ({C}2v symmetry) and c-{{CC}}13{{CH}}2 (Cs symmetry), have been observed in the 1–3 mm band toward the low-mass star-forming region L1527. We have detected 7, 3, and 6 lines of c-C3H2, c-{}13{{CCCH}}2, and c-{{CC}}13{{CH}}2, respectively, with the Nobeyama 45 m telescope and 34, 6, and 13 lines, respectively, with the IRAM 30 m telescope, where seven, two, and two transitions, respectively, are observed with both telescopes. With these data, we have evaluated the column densities of the normal and 13C isotopic species. The [c-C3H2]/[c-{}13{{CCCH}}2] ratio is determined to be 310 ± 80, while the [c-C3H2]/[c-{{CC}}13{{CH}}2] ratio is determined to be 61 ± 11. The [c-C3H2]/[c-{}13{{CCCH}}2] and [c-C3H2]/[c-{{CC}}13{{CH}}2] ratios expected from the elemental 12C/13C ratio are 60–70 and 30–35, respectively, where the latter takes into account the statistical factor of 2 for the two equivalent carbon atoms in c-C3H2. Hence, this observation further confirms the dilution of the 13C species in carbon-chain molecules and their related molecules, which are thought to originate from the dilution of 13C+ in the gas-phase C+ due to the isotope exchange reaction: {}13{{{C}}}++{CO}\\to {}13{CO}+{{{C}}}+. Moreover, the abundances of the two 13C isotopic species are different from each other. The ratio of c-{}13{{CCCH}}2 species relative to c-{{CC}}13{{CH}}2 is determined to be 0.20 ± 0.05. If 13C were randomly substituted for the three carbon atoms, the [c-{}13{{CCCH}}2]/[c-{{CC}}13{{CH}}2] ratio would be 0.5. Hence, the observed ratio indicates that c-{{CC}}13{{CH}}2 exists more favorably. Possible origins of the different abundances are discussed. Based on observations carried out with the IRAM 30 m Telescope and the NRO 45 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). NRO is a branch of the National Astronomical Observatory of Japan

  3. The use of δ13C isotope ratio mass spectrometry for methamphetamine profiling: comparison of ephedrine and pseudoephedrine-based samples to P2P-based samples.

    PubMed

    Toske, Steven G; Morello, David R; Berger, Jennifer M; Vazquez, Etienne R

    2014-01-01

    Differentiating methamphetamine samples produced from ephedrine and pseudoephedrine from phenyl-2-propanone precursors is critical for assigning synthetic route information for methamphetamine profiling. The use of isotope ratio mass spectrometry data is now a key component for tracking precursor information. Recent carbon (δ(13)C) isotope results from the analysis of numerous methamphetamine samples show clear differentiation for ephedrine and pseudoephedrine-produced samples compared to P2P-produced samples. The carbon isotope differences were confirmed from synthetic route precursor studies. PMID:24378294

  4. Rapid sample throughput for biomedical stable isotope tracer studies.

    PubMed

    Preston, T; McMillan, D C

    1988-10-01

    Typical 13C or 15N tracer studies generate large numbers of samples. Instrumentation capable of rapid automated analysis is therefore of importance as a practical alternative to conventional isotope methodology. Although biomedical sample nature is diverse, experimenters often require analysis of substrates and products of particular biochemical pathways. Clearly, reaction products can contain considerably less isotope tracer than precursors. Analytical techniques thus need to accommodate samples of widely varying nature, size and isotope enrichment. In the clinical field, where stable isotopes are increasingly used to study protein, carbohydrate and fat metabolism, analysis of the isotope ratio of a substrate infused into the plasma and a product of its metabolism is often required. Conventional analytical approaches demand access to two mass spectrometers: isotope ratio mass spectrometry (IRMS) for isotope analysis of the relatively large concentrations of low-enrichment metabolic product, and gas chromatography/mass spectrometry (GC/MS) for analysis of the infused substrate often present at high enrichment but low concentration offers a practical alternative to the conventional approaches that is rapid and automatic. In addition to providing a considerably less complex and costly alternative to conventional instrumentation, a single CF-IRMS instrument can also analyse small quantities of low-enrichment metabolites with superior performance than either of the alternative approaches. CF-IRMS is illustrated using results from constant-infusion studies in human protein and fat metabolism which require measurement of the isotope enrichment in submicromolar quantities of plasma substrates together with analysis of larger quantities of their oxidation products, urinary nitrogen and breath CO2. PMID:3149535

  5. Stable isotopes in Lithuanian bioarcheological material

    NASA Astrophysics Data System (ADS)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Schaen, A. J.

    2010-12-01

    Stable isotopic analysis of sedimentary rocks can be used to reconstruct past geologic changes in the elevation and climate of topographic features such as mountain ranges and plateaus. The Tibetan Plateau is an ideal field laboratory for conducting this type of study because of the Plateau’s extreme topographic relief and relatively recent geologic growth. Here we present oxygen and carbon isotope compositions from a suite of sedimentary rock samples taken from the western Turpan Basin in northwestern China. This area of the basin collects sediment from weathering and erosion of the Bogda Shan located to the north. The goal of this study is to analyze changes in the stable isotope composition as a function of stratigraphic position to reconstruct paleoelevations and paleoclimates in this part of the Tibetan Plateau. The sedimentary rock samples analyzed in this study are Late Jurassic to Neogene age and are primarily mudstone, siltstone, fine sandstone along with lesser limestone. Samples were powered and then dissolved with phosphoric acid at 72οC. The liberated CO2 gas was then analyzed using a Finnigan Delta Plus XL mass spectrometer with a gasbench inlet system. Oxygen isotope values range from -13.72 to -1.62‰ (PDB) and exhibit a large scale trend to more negative values toward the top of the stratigraphic sequence. Superimposed on this large scale trend are systematic variations in isotopic composition as a function of age. The most positive δ18O values occur at approximately 160, 115, 60, and 5 ma. Conversely, δ18O minima are observed at 150, 90, and 40 ma. δ13C values range from -10.69‰ to 1.40‰ (PDB). The most positive δ13C values (-4.3 to 1.4) occur from 120-160 ma. Younger samples display small scale variations with age with notable δ13C minima of -10.7, -14.7, and -7.6‰ at 108, 80, and 17 ma, respectively. The variable δ18O and positive δ13C values from the Jurassic (145-160 ma) are consistent with an arid climate and high atmospheric

  7. Stable isotope and elemental analysis in ants.

    PubMed

    Smith, Chris R; Tillberg, Chadwick V

    2009-07-01

    Over the past 20 yr, the use of stable isotopes to infer feeding ecology and the examination of how energetic and elemental exchanges are affected by and affect life (ecological stoichiometry) have gained momentum. The ecological diversity of ants makes them interesting models to explore dietary ecology and their role in food webs. Moreover, their ecological dominance in most habitats facilitates sampling. The protocol described here will produce samples adequate for submission to most labs that specialize in high-throughput analysis of stable isotopes; one should check with any particular lab for specific submission instructions. Note, however, that this protocol is designed specifically for the quantification of the natural abundance of stable isotopes; it does not cover the preparation of trace samples. PMID:20147207

  8. Atmospheric Aerosol Investigation In Vilnius using Stable Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Masalaite, Agne; Garbaras, Andrius; Remeikis, Vidmantas

    2013-04-01

    The effects of aerosols on the atmosphere, climate, and public health are among the central topics in current environmental research. Spatially urban air pollution is a major public concern world-wide.In this study the results of experimental research are presented, the basis of which is the investigation of 13C/12C variations δ13C of stable carbon isotopes in total carbonaceous aerosols in Vilnius city, Lithuania. The main aim of the work is to identify the origin of carbonaceous aerosols. Two autumns and one spring sampling campaign were designed with the aim to determine the changes in the air caused by the beginning/end of the heating season. The experiment was performed during several sampling periods. The first period lasted from 26 November to 06 December 2010. The second was from 04 April to 16 May 2011. The third was from 12 to 29 October 2012. Atmospheric aerosols, according to their aerodynamic diameters, were collected with an eleven-stage impactor "MOUDI". The stages have 50% aerodynamic diameter cut-offs of 18.0, 10.0, 5.6, 3.2, 1.8, 1.0, 0.56, 0.32, 0.18, 0.1 and 0.056 μm, for stages 1-11, respectively. The analysis proceeds essentially in two stages. In the first, MOUDI foils were analyzed with EA-IRMS (FlashEA 1112 coupled to ThermoFinnigan Delta Plus Advantage). Half of the foil was measured directly (TC δ13C values). The rest was heated in the oven (400 °C) to remove organic part and measured EC+CC δ13C values (carbonates were not removed with acid). During the second stage of the analysis, corrections are made and OC δ13C values were calculated using isotopic balance equation: . As the main aim of the study was to identify the origin of incoming carbonaceous aerosols, air mass back trajectories were calculated using the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model.

  9. Linking Isotopes and Panmixia: High Within-Colony Variation in Feather δ2H, δ13C, and δ15N across the Range of the American White Pelican

    PubMed Central

    Reudink, Matthew W.; Kyle, Christopher J.; McKellar, Ann E.; Somers, Christopher M.; Reudink, Robyn L. F.; Kyser, T. Kurt; Franks, Samantha E.; Nocera, Joseph J.

    2016-01-01

    Complete panmixia across the entire range of a species is a relatively rare phenomenon; however, this pattern may be found in species that have limited philopatry and frequent dispersal. American white pelicans (Pelecanus erythrorhyncos) provide a unique opportunity to examine the role of long-distance dispersal in facilitating gene flow in a species recently reported as panmictic across its broad breeding range. This species is also undergoing a range expansion, with new colonies arising hundreds of kilometers outside previous range boundaries. In this study, we use a multiple stable isotope (δ2H, δ13C, δ15N) approach to examine feather isotopic structuring at 19 pelican colonies across North America, with the goal of establishing an isotopic basemap that could be used for assigning individuals at newly established breeding sites to source colonies. Within-colony isotopic variation was extremely high, exceeding 100‰ in δ2H within some colonies (with relatively high variation also observed for δ13C and δ15N). The high degree of within-site variation greatly limited the utility of assignment-based approaches (42% cross-validation success rate; range: 0–90% success). Furthermore, clustering algorithms identified four likely isotopic clusters; however, those clusters were generally unrelated to geographic location. Taken together, the high degree of within-site isotopic variation and lack of geographically-defined isotopic clusters preclude the establishment of an isotopic basemap for American white pelicans, but may indicate that a high incidence of long-distance dispersal is facilitating gene flow, leading to genetic panmixia. PMID:26974163

  10. Stable isotope investigation of insect and plant use in the diets of two Puerto Rican bat species

    EPA Science Inventory

    We used stable isotope13C, δ15N) analysis to estimate the importance of plants and insects to the diet of two nectar-feeding bats on Puerto Rico, the brown flower bat (Erophylla bombifrons) and the Greater Antillean long-tongued bat (Monophyllus redmani). Stable carbon and nit...

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

    PubMed Central

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

    2015-01-01

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

  12. In folio respiratory fluxomics revealed by 13C isotopic labeling and H/D isotope effects highlight the noncyclic nature of the tricarboxylic acid "cycle" in illuminated leaves.

    PubMed

    Tcherkez, Guillaume; Mahé, Aline; Gauthier, Paul; Mauve, Caroline; Gout, Elizabeth; Bligny, Richard; Cornic, Gabriel; Hodges, Michael

    2009-10-01

    While the possible importance of the tricarboxylic acid (TCA) cycle reactions for leaf photosynthesis operation has been recognized, many uncertainties remain on whether TCA cycle biochemistry is similar in the light compared with the dark. It is widely accepted that leaf day respiration and the metabolic commitment to TCA decarboxylation are down-regulated in illuminated leaves. However, the metabolic basis (i.e. the limiting steps involved in such a down-regulation) is not well known. Here, we investigated the in vivo metabolic fluxes of individual reactions of the TCA cycle by developing two isotopic methods, (13)C tracing and fluxomics and the use of H/D isotope effects, with Xanthium strumarium leaves. We provide evidence that the TCA "cycle" does not work in the forward direction like a proper cycle but, rather, operates in both the reverse and forward directions to produce fumarate and glutamate, respectively. Such a functional division of the cycle plausibly reflects the compromise between two contrasted forces: (1) the feedback inhibition by NADH and ATP on TCA enzymes in the light, and (2) the need to provide pH-buffering organic acids and carbon skeletons for nitrate absorption and assimilation. PMID:19675152

  13. Chromium stable isotope fractionation during adsorption

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    Chromium is a common anthropogenic contaminant in ground water. It is redox-active; the two common valences in natural waters are Cr(VI), which is highly soluble and toxic, and Cr(III), which is relatively insoluble. Redox reactions control Cr mobility in aqueous solutions with Cr(VI) reduction to Cr(III) controlling the attenuation of Cr in groundwater. Our previous study demonstrated that abiotic Cr(VI) reduction causes an isotope fractionation of -3.5 permil (53Cr/52Cr) and isotopes can therefore be used to calculate the extent of reduction. In the present study, experiments were conducted to measure Cr isotope fractionation during Cr(VI) sorption on Al203. Sorption of Cr(VI) could be important as a small isotope fractionation may get amplified along the edges of a Cr(VI) contaminated plume. A previous study demonstrated a similar process with Fe isotopes on anion exchange resin. Initial solutions of 200 mg/l Cr(VI) (as K2Cr2O7) and 0.1 mM KCl were made up. Sufficient solid Al203 was added to achieve 50% sorption. After equilibration, the solution was extracted by centrifuging and filtering with a 0.2 micron filter. Al203 was then added again to result in a further 50% sorption of the remaining Cr(VI). This process was repeated 10 times to amplify any isotopic fractionation between dissolved and adsorbed Cr(VI). The instantaneous stable isotope fractionation was calculated based on the δ 53Cr values of the initial and final Cr(VI) solutions. The results show that the stable isotope values measured in the solutions after the ten steps were within the uncertainty of the isotope value of the initial solution. Therefore, no significant stable isotope fractionation occurred. We are presently conducting experiments with goethite and expect similar results. Therefore, any fractionation of chromium stable isotopes observed in contaminant plumes are a result of processes other than adsorption (i.e., reduction).

  14. Diurnal behavior of the carbon dioxide flux and change in the isotopic ratio δ13C in surface and near-bottom water in littoral of Lake Baikal

    NASA Astrophysics Data System (ADS)

    Panchenko, Mikhail V.; Domysheva, Valentina M.; Padalko, Natalia L.; Chernikov, Eugenii V.; Prazdnichnykh, Maxim I.; Tumakov, Alexander G.; Pestunov, Dmitrii A.

    2014-11-01

    Lake Baikal is one of the unique natural environments in Siberia which, to a large extent, affects the state of the nature in this region. The processes of gas exchange in the "water-atmosphere" system have been studied in Lake Baikal since 2002. The main purpose of the integrated investigations of exchange of carbon-containing gases in the water-atmosphere system in Lake Baikal is to study the contribution of physical, chemical, and biological components of the process and their interrelation with the intensity and rhythms of the fluxes. In 2013, the integrated measurements in the littoral area of Baikal were complemented with studies of the diurnal dynamics of isotopic ratio δ 13C in the surface and near-bottom water, which were not yet performed in Baikal before. In this work, we analyze first results of the joint analysis of RO2 fluxes in the "atmosphere - water surface" system and δ 13C, obtained in August 2013 in the littoral area of South Baikal. It is shown that d13C markedly increases in the surface waters at daylight time. In nighttime period, there takes place a reverse process, when δ 13C of the surface water approaches δ 13C, which is recorded for near-bottom water.

  15. A New Tool for NMR Crystallography: Complete (13)C/(15)N Assignment of Organic Molecules at Natural Isotopic Abundance Using DNP-Enhanced Solid-State NMR.

    PubMed

    Märker, Katharina; Pingret, Morgane; Mouesca, Jean-Marie; Gasparutto, Didier; Hediger, Sabine; De Paëpe, Gaël

    2015-11-01

    NMR crystallography of organic molecules at natural isotopic abundance (NA) strongly relies on the comparison of assigned experimental and computed NMR chemical shifts. However, a broad applicability of this approach is often hampered by the still limited (1)H resolution and/or difficulties in assigning (13)C and (15)N resonances without the use of structure-based chemical shift calculations. As shown here, such difficulties can be overcome by (13)C-(13)C and for the first time (15)N-(13)C correlation experiments, recorded with the help of dynamic nuclear polarization. We present the complete de novo (13)C and (15)N resonance assignment at NA of a self-assembled 2'-deoxyguanosine derivative presenting two different molecules in the asymmetric crystallographic unit cell. This de novo assignment method is exclusively based on aforementioned correlation spectra and is an important addition to the NMR crystallography approach, rendering firstly (1)H assignment straightforward, and being secondly a prerequisite for distance measurements with solid-state NMR. PMID:26485326

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

    NASA Astrophysics Data System (ADS)

    Mathukumalli, B.; Alagappan, R.

    2005-12-01

    Stable isotope13C & δ15N) approach was applied to understand carbon biogeochemistry and trophic dynamics in an Indian coastal mangrove wetland. The δ13C and δ15N values of potential nutrient sources (mangrove plant leaves, lichen, sediment and suspended material) and in seven species of consumers (invertebrates) were measured. The value of δ13C and δ15N isotopes of different potential nutrient sources and the consumers determine the sources of nutrients for the invertebrate consumer community of the mangrove. There is a significant variation in the stable carbon in the nutrient sources; however, δ15N signatures were not significantly different among the different potential nutrient sources. Organic matter in the sediments under the mangrove vegetation was characterized by relatively negatively fractionated and moderately high C:N ratios, indicating that mangrove derived organic matter was the principal diet source for the invertebrate consumer communities in the mangrove ecosystem. Invertebrates in the mangrove showed a wide range of δ13C signatures and are enriched relative to the mangrove leaf stable isotope values. Micro-environmental differences certainly drive the variability in the nutrient sources and consumable nature among the different regions of the ecosystem. Therefore, further research is needed to determine whether carbon assimilation is different from one zone to another.

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

    PubMed

    Colabuono, Fernanda I; Barquete, Viviane; Taniguchi, Satie; Ryan, Peter G; Montone, Rosalinda C

    2014-06-15

    Carbon and nitrogen stable isotopes in albatrosses and petrels collected off southern Brazil were compared with concentrations of organochlorine contaminants (OCs). δ(13)C and δ(15)N values, as well as OCs concentrations, exhibited a high degree of variability among individuals and overlap among species. δ(13)C values reflected latitudinal differences among species, with lower values found in Wandering and Tristan Albatrosses and higher values found in Black-browed and Atlantic Yellow-nosed Albatrosses and White-chinned Petrels. Some relationships were found between OCs and stable isotopes, but in general a partial 'uncoupling' was observed between OCs concentrations and stable isotopes ratios (especially for δ(15)N). δ(13)C and δ(15)N values in Procellariiformes tissues during the non-breeding season appear to be a better indicator of foraging habitats than of trophic relationships, which may partially explain the high degree of variability between concentrations of OCs and stable isotopes ratios in birds with a diversified diet and wide foraging range. PMID:24766898

  18. Expeditious syntheses of stable and radioactive isotope-labeled anticonvulsant agent, JNJ-26990990, and its metabolites.

    PubMed

    Lin, Ronghui; Weaner, Larry E; Hoerr, David C; Salter, Rhys; Gong, Yong

    2013-01-01

    Syntheses of stable and radioactive isotope-labeled anticonvulsant agent, JNJ-26990990, that is, N-(benzo[b]thien-3-ylmethyl)-sulfamide and its metabolites are described. [(13)C(15)N]Benzo[b]thiophene-3-carbonitrile was first prepared by coupling of 3-bromo-benzo[b]thiophene with [(13)C(15)N]-copper cyanide. The resultant [(13)C(15)N]benzo[b]thiophene-3-carbonitrile was reduced with lithium aluminum deuteride to give [(13)CD2(15)N]benzo[b]thiophen-3-yl-methylamine; which was then coupled with sulfamide to afford [(13)CD2(15)N]-N-(benzo[b]thien-3-ylmethyl)-sulfamide, the stable isotope-labeled compound with four stable isotope atoms. Direct oxidation of [(13)CD2(15)N]-N-(benzo[b]thien-3-ylmethyl)-sulfamide with hydrogen peroxide and peracetic acid gave the stable isotope-labeled sulfoxide and sulfone metabolites. On the other hand, radioactive (14)C-labeled N-(benzo[b]thien-3-ylmethyl)-sulfamide was prepared conveniently by sequential coupling of 3-bromo-benzo[b]thiophene with [(14)C]-copper cyanide, reduction of the carbonitrile to carboxaldehyde, and reductive amination with sulfamide. PMID:24285137

  19. Stable isotopes confirm a coastal diet for critically endangered Mediterranean monk seals.

    PubMed

    Karamanlidis, Alexandros A; Curtis, P Jeff; Hirons, Amy C; Psaradellis, Marianna; Dendrinos, Panagiotis; Hopkins, John B

    2014-01-01

    Understanding the ecology and behaviour of endangered species is essential for developing effective management and conservation strategies. We used stable isotope analysis to investigate the foraging behaviour of critically endangered Mediterranean monk seals (Monachus monachus) in Greece. We measured carbon and nitrogen isotope ratios (expressed as δ(13)C and δ(15)N values, respectively) derived from the hair of deceased adult and juvenile seals and the muscle of their known prey to quantify their diets. We tested the hypothesis that monk seals primarily foraged for prey that occupy coastal habitats in Greece. We compared isotope values from seal hair to their coastal and pelagic prey (after correcting all prey for isotopic discrimination) and used these isotopic data and a stable isotope mixing model to estimate the proportion of coastal and pelagic resources consumed by seals. As predicted, we found that seals had similar δ(13)C values as many coastal prey species and higher δ(13)C values than pelagic species; these results, in conjunction with mean dietary estimates (coastal=61 % vs. pelagic=39 %), suggest that seals have a diverse diet comprising prey from multiple trophic levels that primarily occupy the coast. Marine resource managers should consider using the results from this study to inform the future management of coastal habitats in Greece to protect Mediterranean monk seals. PMID:25014121

  20. Non-lethal sampling of walleye for stable isotope analysis: a comparison of three tissues

    USGS Publications Warehouse

    Chipps, Steven R.; VanDeHey, J.A.; Fincel, M.J.

    2012-01-01

    Stable isotope analysis of fishes is often performed using muscle or organ tissues that require sacrificing animals. Non-lethal sampling provides an alternative for evaluating isotopic composition for species of concern or individuals of exceptional value. Stable isotope values of white muscle (lethal) were compared with those from fins and scales (non-lethal) in walleye, Sander vitreus (Mitchill), from multiple systems, size classes and across a range of isotopic values. Isotopic variability was also compared among populations to determine the potential of non-lethal tissues for diet-variability analyses. Muscle-derived isotope values were enriched compared with fins and depleted relative to scales. A split-sample validation technique and linear regression found that isotopic composition of walleye fins and scales was significantly related to that in muscle tissue for both δ13C and δ15N (r2 = 0.79–0.93). However, isotopic variability was significantly different between tissue types in two of six populations for δ15N and three of six populations for δ13C. Although species and population specific, these findings indicate that isotopic measures obtained from non-lethal tissues are indicative of those obtained from muscle.

  1. Stable carbon isotope analysis in a South Texas cave: Investigating sources of CO2 production

    NASA Astrophysics Data System (ADS)

    Thompson, Reece

    Studies of interactions between modern local climate, cave atmosphere, and ?13C ratios are needed to determine sources of CO2 in caves, and the cycles of seasonal variations that alter karst geochemistry. A seasonal study, focusing on the analysis of stable isotopes collected from a modern cave system, was conducted in Robber Baron Cave (RBC) in order to identify sources of CO2 in its atmosphere. Determining what conditions affect cave morphology and the transfer path of carbon through a cave system is necessary in order to assess the role of caves in the carbon cycle and correctly interpret past ecological changes. This study investigates the extent that stable isotopic values of carbon in CO2 are affected by CO2 sourced from soils, bedrock, atmospheric air, and vegetation, and how ?13C signals are transmitted in a modern cave system. This study also measures how ventilation affects CO2 concentration and ?13C on seasonal scales. In-cave air grab samples were collected monthly at various transects located in RBC in order to measure CO2 composition in addition to factors such as temperature, and barometric pressure. Soil gas and limestone bedrock were also collected and tested for ?13C composition. Air samples were analyzed using an Ambient Air-Model G2101-I Picarro Cavity Ring-Down Spectroscopy Analyzer for both the concentration and ?13C isotopic value of CO2. These values were then compared to isotopic values of known sources of CO2 in order to determine possible sources of CO2 that result in high CO2 concentrations found in RBC. The background stable isotopic value of carbon from CO2 measured in RBC is -19.1‰ VPDB.

  2. Investigating the Formation of Pedogenic Carbonate Using Stable Isotopes

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    The stable isotope composition of pedogenic carbonate has been used as a paleoenvironmental proxy because it is thought to form in isotopic equilibrium with soil CO2 and soil water, which are influenced by vegetation type and atmospheric circulation patterns, respectively. However, the isotopic composition of soil CO2 and soil water change seasonally and it is not known what portion of this variability is recorded by the isotopic composition of pedogenic carbonate. It is generally believed that carbonate precipitation in soils is driven by evaporative concentration of Ca ions and/or decreasing soil pCO2. We seek to improve the proxy by determining the seasonality of pedogenic carbonate formation, in particular whether pedogenic carbonate forms during the wet season after individual rainstorms or during seasonal drying following the wet season. This was done by comparing the variations in carbon and oxygen isotope composition of soil CO2 with the isotopic composition of proximally located, newly-formed carbonates. Soil CO2 and incipient pedogenic carbonate coatings were collected in a very young (< 500yrs) soil developing in an inset terrace on the piedmont of the Sandia Mountains, central New Mexico. We also measure soil temperatures at the same site. In May 2006, at the end of the driest 6-month period on record in central New Mexico, soil CO2 profiles displayed a 2‰ decrease in δ13C values with depth from 9 to 100 cm. In August 2006, the shapes of the profiles were similar, but the δ13C values were 3-4‰ lower at each depth than in May. These results can be explained by an increase in respiration rate during the latter half of the summer (the wettest on record) when monsoon rainfall maintained high moisture contents in soils across New Mexico. Calculated δ13C values of calcite in equilibrium with May (but not August) soil CO2 agree with measured carbonate δ13C values below 20 cm depth. Very shallow carbonate has anomalously high δ13C values. Measurements

  3. Stable Isotope Evidence for Planetary Differentiation

    NASA Astrophysics Data System (ADS)

    Shahar, A.; Mao, W. L.; Schauble, E. A.; Caracas, R.; Reagan, M. M.; Gleason, A. E.

    2015-12-01

    Planetary differentiation occurred at high temperature and varying oxygen fugacity, on bodies with varying compositions and internal pressures. The specific conditions at which bodies differentiated and the chemical fingerprints left by differentiation can be investigated by measuring stable isotope ratios in natural samples. Much can be learned by combining those data with experiments that systematically investigate the chemical and physical conditions within differentiating bodies. In this talk we focus on one variable in particular that has not been well defined with respect to stable isotope fractionation: pressure. We will present new iron isotope data on how pressure affects isotope fractionation factors for a number of iron compounds relative to silicate. The processes governing iron isotope fractionation in igneous rocks have been debated extensively over the past decade. Analyses of natural samples show that iron isotopes are fractionated at both the whole rock and mineral scales. This fractionation has been interpreted to be a result of several processes including a possible signature of high pressure core formation. We have collected new high pressure synchrotron nuclear resonant inelastic x-ray scattering data from Sector 16-ID-D at the Advanced Photon Source on 57Fe enriched Fe, FeO, FeHx and Fe3C. Our data show clear trends with pressure implying that not only does pressure have an effect on the iron isotope beta factors but also a fractionation amongst the alloys. This suggests that depending on the light element in the core, there will be a different resulting signature in the iron isotope record. We will discuss the likelihood of different light elements in the core based on these results, as well as the theoretical predictions for the same phases. Finally, we will present the fractionation expected between metal and silicate at high pressure and high temperature in order to determine if core formation would indeed leave an isotopic signature in

  4. UNCERTAINTY IN SOURCE PARTITIONING USING STABLE ISOTOPES

    EPA Science Inventory

    Stable isotope analyses are often used to quantify the contribution of multiple sources to a mixture, such as proportions of food sources in an animal's diet, C3 vs. C4 plant inputs to soil organic carbon, etc. Linear mixing models can be used to partition two sources with a sin...

  5. 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.

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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

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

    PubMed Central

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

    2015-01-01

    The stable carbon and nitrogen isotope composition of animal tissues is commonly used to trace wildlife diets and analyze food chains. Changes in an animal’s isotopic values over time are generally assumed to indicate diet shifts or, less frequently, physiological changes. Although plant isotopic values are known to correlate with climatic seasonality, only a few studies restricted to aquatic environments have investigated whether temporal isotopic varia-tion in consumers may also reflect environmental baselines through trophic propagation. We modeled the monthly variation in carbon and nitrogen isotope values in whole blood of four insectivorous bat species occupying different foraging niches in southern Spain. We found a common pattern of isotopic variation independent of feeding habits, with an overall change as large as or larger than one trophic step. Physiological changes related to reproduction or to fat deposition prior to hibernation had no effect on isotopic variation, but juvenile bats had higher 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 inte-grated in animals’ isotope values will be crucial for developing reliable methods to use stable isotopes as dietary tracers. PMID:25700080

  7. Stable isotope investigations of chlorinated aliphatic hydrocarbons.

    SciTech Connect

    Abrajano, T.; Heraty, L. J.; Holt, B. D.; Huang, L.; Sturchio, N. C.

    1999-06-01

    Stable isotope ratio measurements for carbon (C) and chlorine (Cl) can be used to elucidate the processes affecting transformation and transportation of chlorinated aliphatic hydrocarbons (CAHs) in the environment. Methods recently developed in our laboratory for isotopic analysis of CAHs have been applied to laboratory measurements of the kinetic isotope effects associated with aerobic degradation of dichloromethane (DCM) and with both anaerobic and aerobic cometabolic degradation of trichlomethene (TCE) in batch and column microbial cultures. These experimental determinations of fractionation factors are crucial for understanding the behavior of CAHs in complex natural systems, where the extent of biotransformation can be masked by dispersion and volatilization. We have also performed laboratory investigations of kinetic isotope effects accompanying evaporation of CAHs, as well as field investigations of natural attenuation and in situ remediation of CAHs in a number of contaminated shallow aquifers at sites operated by the federal government and the private sector.

  8. The potential for application of ink stable isotope analysis in questioned document examination.

    PubMed

    Chesson, Lesley A; Tipple, Brett J; Barnette, Janet E; Cerling, Thure E; Ehleringer, James R

    2015-01-01

    We investigated a novel application of stable isotope abundance analysis of nitrogen (15N), carbon (13C), hydrogen (2H), and oxygen (18O) to characterize pen ink. We focused on both ballpoint and gel pen inks. We found that the isotope ratios of ink from pens purchased together in a package were similar and within-package stable isotope ratio variability was not significantly larger than the variability of isotope reference materials used during analysis. In contrast, the isotope ratios of ink from pens of the same brand purchased in three states of the continental USA were significantly different from each other and there was isotope ratio variation among pens of the same brand but different, unknown production periods. The stable isotope ratios of inked paper were statistically distinguishable using measured δ15N values. Paper inked with different gel pens was statistically distinguishable using measured δ2H values. The capacity of stable isotope ratios to differentiate among ballpoint inks as well as gel inks shows that stable isotope analysis may be a useful and quantifiable investigative technique for questioned document examination, although current sample size requirements limit its utility. Application of the technique in casework will require the development of micro-scale sampling and analysis methods. PMID:25577004

  9. Stable isotopes determination in some Romanian wines.

    PubMed

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

    2012-06-01

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

  10. Relating species and functional diversity using stable isotope probing

    NASA Astrophysics Data System (ADS)

    Prosser, J. I.; Rangel-Castro, J. I.; Mahmood, S.; Nicol, G.; Meharg, A. A.; Killham, K. S.

    2004-12-01

    Microbial communities play an essential role in biogeochemical cycles and analysis of laboratory cultures has provided much information on biochemical processes and physiological characteristics of functional groups of microorganisms responsible for these processes. However, the majority of microorganisms cannot be grown readily in laboratory culture and cultivation-independent molecular techniques are required for analysis of community structure and diversity. These techniques have demonstrated considerable microbial diversity in natural communities and have revealed the existence of abundant microorganisms belonging to novel, previously unsuspected microbial groups. Molecular analysis of natural communities typically provides little information on links between specific microorganisms and the biogeochemical processes that they carry out. We are therefore ignorant of the significance of microbial diversity for ecosystem processes and of the ecosystem function of uncultivated, but abundant microbial groups. Stable isotope probing enables identification of which members of a community are involved in the utilisation of specific substrates, particularly carbon substrates. It involves amendment of environmental samples, or field application with 13C-labelled carbon substrates and, after a period of exposure, extraction of nucleic acids and separation of 13C-labelled (heavy) and 12C-labelled (light) nucleic acid pools by density gradient centrifugation. The heavy nucleic acid pool will be derived only from organisms assimilating the labelled substrate.Molecular analysis of this pool provides information on identity and relative abundance of active members of the community. The technique therefore enables in situ functional analysis of microbial groups without the requirement for laboratory cultivation. Stable isotope probing has been used to determine which organisms are involved in the degradation of specific organic substrates, including recalcitrant compounds, and

  11. The Stable Isotopic Composition of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Yakir, D.

    2003-12-01

    When a bean leaf was sealed in a closed chamber under a lamp (Rooney, 1988), in two hours the atmospheric CO2 in the microcosm reached an isotopic steady state with a 13C abundance astonishingly similar to the global mean value of atmospheric CO2 at that time (-7.5‰ in the δ13C notation introduced below). Almost concurrently, another research group sealed a suspension of asparagus cells in a different type of microcosm in which within about two hours the atmospheric O2 reached an isotopic steady state with 18O enrichment relative to water in the microcosm that was, too, remarkably similar to the global-scale offset between atmospheric O2 and mean ocean water (21‰ versus 23.5‰ in the δ18O notation introduced below; Guy et al., 1987). These classic experiments capture some of the foundations underlying the isotopic composition of atmospheric CO2 and O2. First, in both cases the biological system rapidly imposed a unique isotopic value on the microcosms' atmosphere via their massive photosynthetic and respiratory exchange of CO2 and O2. Second, in both cases the biological system acted on materials with isotopic signals previously formed by the global carbon and hydrological cycles. That is, the bean leaf introduced its previously formed organic matter (the source of the CO2 respired into microcosm's atmosphere), and the asparagus cells were introduced complete with local tap water (from which photosynthesis released molecular oxygen). Therefore, while the isotopic composition of the biological system used was slave to long-term processes, intense metabolic processes centered on few specific enzymes (Yakir, 2002) dictated the short-term atmospheric composition.In a similar vein, on geological timescales of millions of years, the atmosphere and its isotopic composition are integral parts of essentially a single dynamic ocean-atmosphere-biosphere system. This dynamic system exchanges material, such as carbon and oxygen, with the sediments and the lithosphere via

  12. Isotopic finger-printing of active pharmaceutical ingredients by 13C NMR and polarization transfer techniques as a tool to fight against counterfeiting.

    PubMed

    Bussy, Ugo; Thibaudeau, Christophe; Thomas, Freddy; Desmurs, Jean-Roger; Jamin, Eric; Remaud, Gérald S; Silvestre, Virginie; Akoka, Serge

    2011-09-30

    The robustness of adiabatic polarization transfer methods has been evaluated for determining the carbon isotopic finger-printing of active pharmaceutical ingredients. The short time stabilities of the adiabatic DEPT and INEPT sequences are very close to that observed with the one pulse sequence, but the DEPT long time stability is not sufficient for isotopic measurements at natural abundance or low enrichment. Using the INEPT sequence for (13)C isotopic measurements induces a dramatic reduction in the experimental time without deterioration in short time or long time stability. It appears, therefore, to be a method of choice for obtaining the isotopic finger-print of different ibuprofen samples in a minimum time. The results obtained on 13 commercial ibuprofen samples from different origins show that this strategy can be used effectively to determine (13)C distribution within a given molecule and to compare accurately differences in the isotopic distribution between different samples of the given molecule. The present methodology is proposed as a suitable tool to fight against counterfeiting. PMID:21872037

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  14. Stable Isotopic Variations of a Stalagmite from Belum Cave, India: Potential for Monsoon Reconstruction

    NASA Astrophysics Data System (ADS)

    Allu, N. C.; Tiwari, M.; Yadava, M. G.; Nguyen, D. C.; Shen, C.; Belangaonkar, S. P.; Ramesh, R.

    2011-12-01

    Speleothems, known to record environmental changes on land, are important palaeoclimatic archives for the terrestrial environment as they possess a remarkably accurate dating potential. The climatic proxies that can be deciphered from speleothems are stable isotope composition (δ18O, δ13C), organic (humic) matter, growth rate, and trace element composition, as well as luminescent laminae, which may display annual rhythms. In the present work, we have studied speleothems from a new semi-arid region in southern India for exploring their potential for reconstructing monsoon history during the last interglacial-glacial transition. The study area is the Belum caves, Andhra Pradesh. A 54 cm long fossil stalagmite was investigated for oxygen and carbon isotope (δ18O, δ13C) compositions. Results from radiocarbon dating method indicate that the stalagmite is older than 40 kyr. Its age interval obtained by U-Th dating method vary from 41 kyr to 158 kyr. Average values δ18O and δ13C, observed along the growth direction, are -5.8 and -5.3 %, respectively. The variations in δ13C are within ~-7.3 to -4.3 %, and for δ18O from -7.1 to -3.9 %. The isotopic values are unlike the other caves in Indian region. While δ18O values are similar, 13C is more enriched. This indicates that the dripping of water could be relatively slower during the growth of the Belum stalagmite and interactions between regional aquifers.

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

    PubMed Central

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

    2013-01-01

    To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ13C and δ15N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ13C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ13C value, while oceanic species showed significantly lower δ13C values. The highest δ15N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ15N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ13C values, but similar δ15N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ13C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area. PMID:24358155

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

    PubMed

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

    2013-01-01

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

  17. Identifying pre-Historic Land use Through Stable Isotope and Geomorphic Analyses

    NASA Astrophysics Data System (ADS)

    White, D. M.; Springer, G. S.; Rowe, H. D.

    2006-12-01

    The effects of prehistoric and modern land use may be recorded in cave stalagmites and clastic sediments as variations in δ13C, which describe the relative influence of C3 versus C4 plants. Mass spectrometry of macerated organic material in the cave sediments display fluctuations in δ13C representing changes in floral composition at the time of deposition. We report unexplained stable isotope excursions (δ13C) in stalagmites of a West Virginia cave that are temporally associated (~ 1850 BP) with Native American presence in the study area. We use spatially explicit, but geographically separated datasets of δ13C in clastic cave sediments to distinguish between pre-European anthropogenic effects, chemical disequilibria, or alternate terrestrial explanations for spatially explicit variations of δ13C. We use a new technique whereby known, independent climate-driven δ13C timelines are subtracted from histories suspected of containing land use signals to uncover anomalies perhaps attributable to prehistoric land use. Hydrologic and geomorphic responses are represented by changes in sediment characteristics and subtle grain size variations. The residual anomalies represent pre-European land use or undiscovered terrestrial processes operating within the watershed. Studies of spatial and temporal variations of δ13C provide an important new tool for our understanding of interactions between humans and ecosystems. Correlating prehistoric land use with subsequent recovery offers the rare opportunity to project ecosystem recovery from modern disturbances.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    Carbon stable isotope13C) records from vascular plant dominated peatlands have been used as a palaeoclimate proxy, but a better empirical understanding of fractionation processes in these ecosystems is required. Here, we test the potential of δ13C analysis of ombrotrophic restiad peatlands in New Zealand, dominated by the wire rush (Empodisma spp.), to provide a methodology for developing palaeoclimatic records. We took surface plant samples alongside measurements of water table depth and (micro)climate over spatial (six sites spanning > 10° latitude) and temporal (monthly measurements over 1 year) gradients and analysed the relationships between cellulose δ13C values and environmental parameters. We found strong, significant negative correlations between δ13C and temperature, photosynthetically active radiation and growing degree days above 0 °C. No significant relationships were observed between δ13C and precipitation, relative humidity, soil moisture or water table depth, suggesting no growing season water limitation and a decoupling of the expected link between δ13C in vascular plants and hydrological variables. δ13C of Empodisma spp. roots may therefore provide a valuable temperature proxy in a climatically sensitive region, but further physiological and sub-fossil calibration studies are required to fully understand the observed signal.

  19. Fate of terrestrial DOC within stream biofilm communities: a stable isotope approach (Invited)

    NASA Astrophysics Data System (ADS)

    Wiegner, T. N.; Kaplan, L.; Ziegler, S. E.; Findlay, R. H.

    2010-12-01

    /or respiration of the 13C-DOC. All PLFAs resolved were enriched in 13C suggesting that 13C-DOC cycled completely through the microbial community during the experiment and the most enriched PLFAs (cy17:0 and cy19:0) are indicative of anaerobic bacteria or physiologically stressed aerobic bacteria. Among the bioreactors exposed to 13C-DOC, the bioreactor with the highest production rate had the highest δ13C PLFA values, suggesting that the incorporation of 13C-DOC into microbial membranes is a function of growth rate. Overall, our results show that a 7% enrichment of 13C-DOC is sufficient for stable isotope probing with microbial lipids and suggest that aerobic and anaerobic heterotrophic bacteria are primarily responsible for taking up DOC, respiring most of it, and transferring the remainder to higher trophic levels to support secondary production within lotic ecosystems.

  20. Protein Stable Isotope Fingerprinting (P-SIF): A New Tool to Understand Natural Isotopic Heterogeneity of Mixed Microbial Ecosystems

    NASA Astrophysics Data System (ADS)

    Pearson, A.; Mohr, W.; Tang, T.; Sattin, S.; Bovee, R.

    2014-12-01

    Protein stable isotope fingerprinting (P-SIF) is a method to measure the carbon isotope ratios of whole proteins separated from complex mixtures, including cultures and environmental samples. The goal of P-SIF is to expose the links between identity and function in microbial ecosystems by (i) determining the ratios of 13C/12C (values of δ13C) for different taxonomic divisions, and (ii) using those values as clues to the metabolic pathways employed by the respective organisms, while (iii) not perturbing the system, i.e., not adding exogenous substrates or isotope labels. To accomplish this, we employ two-dimensional HPLC to resolve a sample containing ca. 5-10 mg of mixed proteins into 960-1440 fractions. Each fraction then is split in two aliquots: The first is digested with trypsin for peptide sequencing, while the second is measured in triplicate using an isotope-ratio mass spectrometer interfaced with a spooling wire microcombustion device. Data from pure cultures show that bacteria have a narrow distribution of protein δ13C values within individual taxa (±0.7-1.2‰, 1σ). This is moderately larger than the mean precision of the triplicate isotope measurements (±0.5‰, 1σ) and may reflect heterogeneous distribution of 13C among the amino acids. When cells from different species are mixed together prior to protein extraction and separation, the results can predict accurately (to within ±1σ) the δ13C values of the original taxa. The number of data points required for this endmember prediction is ≥20/taxon, yielding a theoretical resolution of ca. 10 taxonomic units/sample. Initial tests on environmental samples suggest the approach will be useful to determine the overall trophic breadth of mixed microbial ecosystems.

  1. New Stable Isotope Tropical Paleoclimate Proxies

    NASA Astrophysics Data System (ADS)

    Lawrence, J. R.

    2005-05-01

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

  2. Multi-isotope ((15)N, (18)O and (13)C) indicators of sources and fate of nitrate in the upper stream of Chaobai River, Beijing, China.

    PubMed

    Li, Cai; Jiang, Yongbin; Guo, Xinyue; Cao, Yang; Ji, Hongbing

    2014-11-01

    Dual isotopes of nitrate ((15)N and (18)O) and carbon isotopes of dissolved inorganic carbon ((13)C) together with water chemistry were used to identify the sources and fate of nitrate in the upper stream of Chaobai River, north China. The results show that NO3(-) concentrations ranges from 0.03 mmol L(-1) to 0.80 mmol L(-1). Sampling sites from watershed with dominant forest land had higher NO3(-) concentrations and lower δ(15)N-NO3(-) (<10‰) in the wet season than in the dry season, while those from watershed with more anthropogenic activities had lower NO3(-) concentrations and higher δ(15)N-NO3(-) (>10‰) in the wet season. Compositions of isotopes and chemistry indicated that NO3(-) originated mainly from soil N, sewage and livestock wastes and atmospheric nitrogen. Furthermore, the mixing model suggested that soil N was the major NO3(-) source in the wet season, while the sewage and livestock wastes contributed the most in the dry season. Compared to rivers, the Miyun Reservoir had a higher contribution of atmospheric N and the N input from the upper rivers exerted significant influence over the reservoir. Mineralization and nitrification played an important role in N biogeochemistry based on the isotopes ((15)N and (18)O and (13)C) and chemical data. There appeared to be no significant denitrification in the watershed according to the three isotopes and chemical ions. The combined use of (15)N, (18)O and (13)C proved to be useful for further identification of the sources and fate of nitrate in watersheds with dominant forest land in the wet season. PMID:25283837

  3. Quantifying uncertainty in stable isotope mixing models

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, Stable Isotope Analysis in R (SIAR), a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ15N and δ18O) but all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated

  4. Stable isotopes as indicators of altitudinal distributions and movements in an Ecuadorean hummingbird community.

    PubMed

    Hobson, Keith A; Wassenaar, Len I; Milá, Borja; Lovette, Irby; Dingle, Caroline; Smith, Thomas B

    2003-07-01

    Altitudinal migration and dispersal is an important component of the life history of several temperate and tropical birds but remains poorly understood due to the limited success of mark and recapture techniques. Stable isotopes of hydrogen (deltaD) in rainfall, and to a lesser extent, carbon (delta13C) in plants are known to change with altitude and hence may provide the basis of a technique for tracking the altitudinal movements in birds and other wildlife. We investigated the potential for this technique by measuring delta13C, deltaD, and delta15N values in tail feathers of eight species of hummingbirds ( Phaethornis malaris, P. syrmatophorus, P. guy, Adelomyia melanogenys, Coeligena torquata, C. lutetiae, Metallura baroni, M. williami) along an altitudinal gradient (300-3,290 m asl) in the Andes Mountains of Ecuador. Feather delta13C and deltaD values were correlated and each changed significantly with elevation above 400 m. In general, we found good agreement between feather deltaD values and those predicted from a generalized relationship of precipitation and surface water deltaD with altitude. Similarly, feather delta13C values showed an enrichment of approximately 1.5 per thousand per 1,000 m over the linear portion of the elevational response. Stable-nitrogen isotope values were variable, and so did not provide useful information on elevation in birds, apart from trophic effects. Overall there appears to be good potential for using the (deltaD, delta13C) stable isotope approach to track altitudinal movements and to elucidate previously unrecognized patterns of life history variation in both temperate and tropical species that migrate across elevational isotopic gradients. PMID:12756525

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

    PubMed

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

    1995-01-01

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

  6. Identification of cellulolytic bacteria in soil by stable isotope probing.

    PubMed

    Haichar, Feth El Zahar; Achouak, Wafa; Christen, Richard; Heulin, Thierry; Marol, Christine; Marais, Marie-France; Mougel, Christophe; Ranjard, Lionel; Balesdent, Jérôme; Berge, Odile

    2007-03-01

    Plant residues, mainly made up of cellulose, are the largest fraction of organic carbon material in terrestrial ecosystems. Soil microorganisms are mainly responsible for the transfer of this carbon to the atmosphere, but their contribution is not accurately known. The aim of the present study was to identify bacterial populations that are actively involved in cellulose degradation, using the DNA-stable isotope probing (DNA-SIP) technique. (13)C-cellulose was produced by Acetobacter xylinus and incubated in soil for 7, 14, 30 and 90 days. Total DNA was extracted from the soil, the (13)C-labelled (heavy) and unlabelled (light) DNA fractions were separated by ultracentrifugation, and the structure of active bacterial communities was analysed by bacterial-automated ribosomal intergenic spacer analysis (B-ARISA) and characterized with denaturing gradient gel electrophoresis (DGGE). Cellulose degradation was associated with significant changes in bacterial community structure issued from heavy DNA, leading to the appearance of new bands and increase in relative intensities of other bands until day 30. The majority of bands decreased in relative intensity at day 90. Sequencing and phylogenetic analysis of 10 of these bands in DGGE profiles indicated that most sequences were closely related to sequences from organisms known for their ability to degrade cellulose or to uncultured soil bacteria. PMID:17298363

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

    PubMed

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

    2016-02-01

    Isotopic enrichment factor (Δ, the difference between the δ value of food and a consumer tissue) is an important parameter in using stable isotope analysis (SIA) to reconstruct diets, characterize trophic relationships, elucidate patterns of resource allocation, and construct food webs. Isotopic enrichment factor has been considered as a constancy value across a broad range of animals. However, recent studies showed that the isotopic enrichment factor differed among various types of animals although the magnitude of variation was not clear. Here, we conducted a meta-analysis to synthesize and compare Δ13C and Δ15N among four types of aquatic animals (teleosts, crustaceans, reptiles and molluscs). We searched for papers published before 2014 on Web of Science and CNKI using the key words "stable isotope or isotopic fractionation or fractionation factor or isotopic enrichment or trophic enrichment". Forty-two publications that contain 140 studies on Δ13C and 159 studies on Δ15N were obtained. We conducted three parallel meta-analyses by using three types of weights (the reciprocal of variance as weights, the sample size as weights, and equal weights). The results showed that no significant difference in Δ13C among different animal types (teleosts 1.0 per thousand, crustaceans 1.3 per thousand, reptiles 0.5 per thousand, and molluscs 1.5 per thousand), while Δ15N values were significantly different (teleosts 2.4 per thousand, crustaceans 3.6 per thousand, reptiles 1.0 per thousand and molluscs 2.5 per thousand). Our results suggested that the overall mean of Δ13C could be used as a general enrichment factor, but Δ15N should be chosen according to the type of aquatic animals in using SIA to analyze trophic relationships, patterns of resource allocation and food webs. PMID:27396136

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

    PubMed

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

    2014-10-22

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

  9. Reassessing the stable isotope composition assigned to methane flux from natural wetlands in isotope-constrained budgets

    NASA Astrophysics Data System (ADS)

    Hornibrook, Edward; Maxfield, Peter; Gauci, Vincent; Stott, Andrew

    2013-04-01

    Stable isotope ratios in CH4 preserve information about its origin and history, and are commonly used to constrain global CH4 budgets. Wetlands are key contributors to the atmospheric burden of CH4 and typically are assigned a stable carbon isotope composition of ~-60 permil in isotope-weighted stable isotope models despite the considerable range of δ13C(CH4) values (~ -100 to -40 permil) known to occur in these diverse ecosystems. Kinetic isotope effects (KIEs) associated with the metabolism of CH4-producing microorganisms generate much of the natural variation but highly negative and positive δ13C(CH4) values generally result from secondary processes (e.g., diffusive transport or oxidation by soil methanotrophs). Despite these complexities, consistent patterns exist in the isotope composition of wetland CH4 that can be linked conclusively to trophic status and consequently, natural succession or human perturbations that impact nutrient levels. Another challenge for accurate representation of wetlands in carbon cycle models is parameterisation of sporadic CH4 emission events. Abrupt release of large volumes of CH4-rich bubbles in short periods of time can account for a significant proportion of the annual CH4 flux from a wetland but such events are difficult to detect using conventional methods. New infrared spectroscopy techniques capable of high temporal resolution measurements of CH4 concentration and stable isotope composition can readily quantify short-lived CH4 pulses. Moreover, the isotope data can be used conclusively to determine shifts in the mode of CH4 transport and provide the potential to link initiation of abrupt emission events to forcing by internal or external factors.

  10. Reconstructing infant weaning histories at Roman period Kellis, Egypt using stable isotope analysis of dentition.

    PubMed

    Dupras, Tosha L; Tocheri, Matthew W

    2007-09-01

    Studies of infant feeding and weaning patterns in past populations that rely on a cross-sectional approach must make the assumption that no infant mortality bias exists. Previous investigations of infant weaning patterns at the Dakhleh Oasis, Egypt, relied on cross-sectional isotope data. In this study, we re-examine this weaning pattern, using a simulated longitudinal approach, which does not require any assumptions regarding potential infant mortality biases. This involves examining the dental isotopic signatures of individuals who survived the weaning process. Stable isotope signatures from juveniles and adults (102 individuals, 297 teeth) were examined to reconstruct the weaning history of those that survived the weaning process. Both deciduous and permanent teeth were sampled. Homogenized enamel and dentin samples were isolated from each tooth and analyzed for delta(13)C(ap) and delta(18)O(ap) from the enamel and delta(15)N(coll) and delta(13)C(coll) from dentin collagen. We investigate differences between in utero versus postbirth, preweaning versus postweaning, and juvenile versus adult stable isotope values as reflected in the dentition. A random permutation procedure was used to test for statistically significant differences in stable isotope values between tooth types. Statistically significant differences were observed in all stable isotopes between permanent and deciduous teeth, and between early and later forming permanent teeth in delta(13)C(ap) and delta(15)N(coll) isotopes. These results indicate dietary change between in utero and postbirth, and changes occurring during the weaning period. These results provide a more comprehensive picture of infant weaning practices at Kellis and provide further support that complete weaning occurred by 3 years of age. PMID:17568441

  11. Measurements of 13C/12C methane from anaerobic digesters: comparison of optical spectrometry with continuous-flow isotope ratio mass spectrometry.

    PubMed

    Keppler, Frank; Laukenmann, Stephan; Rinne, Jennifer; Heuwinkel, Hauke; Greule, Markus; Whiticar, Michael; Lelieveld, Jos

    2010-07-01

    Methane production by anaerobic digestion of biomass has recently become more attractive because of its potential for renewable energy production. Analytical tools are needed to study and optimize the ongoing processes in biogas reactors. It is considered that optical methods providing continuous measurements at high temporal resolution of carbon isotope ratios of methane (delta(13)C(CH4)) might be of great help for this purpose. In this study we have tested near-infrared laser optical spectrometry and compared it with conventional continuous-flow isotope ratio mass spectrometry (CF-IRMS) using several methane carbon isotope standards and a large number of biogas samples from batch anaerobic reactors. Results from measurements on these samples were used to determine and compare the precision of the two techniques and to quantify for systematic offsets. With pure standards analytical precision of measurements for delta(13)C(CH4) was found to be in the range of 0.33 and 0.48 per thousand, and 0.09 and 0.27 per thousand for the optical method and CF-IRMS, respectively. Biogas samples showed an average mean deviation of delta(13)C(CH4) of 0.38 per thousand and 0.08 per thousand for the optical method and CF-IRMS, respectively. Although the tested laser optical spectrometer showed a dependence of delta(13)C(CH4) on CH(4) mixing ratio in the range of 500 to 8000 ppm this could be easily corrected. After correction, the delta(13)C(CH4) values usually varied within 0.7 per thousand from those measured by conventional CF-IRMS and thus results from both methods agreed within the given analytical uncertainties. Although the precision of the conventional CF-IRMS is higher than the tested optical system, both instruments were well within the acceptable delta(13)C(CH4) precision required for biogas methane measurements. The advantages of the optical system are its simplicity of operation, speed of analysis, good precision, reduced costs in comparison to IRMS, and the potential

  12. Enhanced understanding of ectoparasite: host trophic linkages on coral reefs through stable isotope analysis

    USGS Publications Warehouse

    Demopoulos, Amanda W. J.; Sikkel, Paul C.

    2015-01-01

    Parasitism, although the most common type of ecological interaction, is usually ignored in food web models and studies of trophic connectivity. Stable isotope analysis is widely used in assessing the flow of energy in ecological communities and thus is a potentially valuable tool in understanding the cryptic trophic relationships mediated by parasites. In an effort to assess the utility of stable isotope analysis in understanding the role of parasites in complex coral-reef trophic systems, we performed stable isotope analysis on three common Caribbean reef fish hosts and two kinds of ectoparasitic isopods: temporarily parasitic gnathiids (Gnathia marleyi) and permanently parasitic cymothoids (Anilocra). To further track the transfer of fish-derived carbon (energy) from parasites to parasite consumers, gnathiids from host fish were also fed to captive Pederson shrimp (Ancylomenes pedersoni) for at least 1 month. Parasitic isopods had 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.

  13. Enhanced understanding of ectoparasite-host trophic linkages on coral reefs through stable isotope analysis.

    PubMed

    Demopoulos, Amanda W J; Sikkel, Paul C

    2015-04-01

    Parasitism, although the most common type of ecological interaction, is usually ignored in food web models and studies of trophic connectivity. Stable isotope analysis is widely used in assessing the flow of energy in ecological communities and thus is a potentially valuable tool in understanding the cryptic trophic relationships mediated by parasites. In an effort to assess the utility of stable isotope analysis in understanding the role of parasites in complex coral-reef trophic systems, we performed stable isotope analysis on three common Caribbean reef fish hosts and two kinds of ectoparasitic isopods: temporarily parasitic gnathiids (Gnathia marleyi) and permanently parasitic cymothoids (Anilocra). To further track the transfer of fish-derived carbon (energy) from parasites to parasite consumers, gnathiids from host fish were also fed to captive Pederson shrimp (Ancylomenes pedersoni) for at least 1 month. Parasitic isopods had δ(13)C and δ(15)N 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 (15)N and depleted in (13)C 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 δ(13)C values consistent with their food source and enriched in (15)N as predicted due to trophic fractionation. These results further indicate that stable isotopes can be an effective tool in deciphering cryptic feeding relationships involving parasites and their consumers, and the role of parasites and cleaners in carbon transfer in coral-reef ecosystems specifically. PMID:25830112

  14. Enhanced understanding of ectoparasite–host trophic linkages on coral reefs through stable isotope analysis

    PubMed Central

    Demopoulos, Amanda W.J.; Sikkel, Paul C.

    2015-01-01

    Parasitism, although the most common type of ecological interaction, is usually ignored in food web models and studies of trophic connectivity. Stable isotope analysis is widely used in assessing the flow of energy in ecological communities and thus is a potentially valuable tool in understanding the cryptic trophic relationships mediated by parasites. In an effort to assess the utility of stable isotope analysis in understanding the role of parasites in complex coral-reef trophic systems, we performed stable isotope analysis on three common Caribbean reef fish hosts and two kinds of ectoparasitic isopods: temporarily parasitic gnathiids (Gnathia marleyi) and permanently parasitic cymothoids (Anilocra). To further track the transfer of fish-derived carbon (energy) from parasites to parasite consumers, gnathiids from host fish were also fed to captive Pederson shrimp (Ancylomenes pedersoni) for at least 1 month. Parasitic isopods had 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. PMID:25830112

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

    PubMed Central

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

    2014-01-01

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

  16. Deuterium-induced isotope effects on the 13C chemical shifts of α-D-glucose pentaacetate.

    PubMed

    Pérez-Hernández, Nury; Álvarez-Cisneros, Celina; Cerda-García-Rojas, Carlos M; Morales-Ríos, Martha S; Joseph-Nathan, Pedro

    2013-03-01

    1,2,3,4,6-Penta-O-acetyl-α-D-glucopyranose and the corresponding [1-(2)H], [2-(2)H], [3-(2)H], [4-(2)H], [5-(2)H], and [6,6-(2)H(2)]-labeled compounds were prepared for measuring deuterium/hydrogen-induced effects on (13)C chemical shift (n)Δ (DHIECS) values. A conformational analysis of the nondeuterated compound was achieved using density functional theory (DFT) molecular models that allowed calculation of several structural properties as well as Boltzmann-averaged (13)C NMR chemical shifts by using the gauge-including atomic orbital method. It was found that the DFT-calculated C-H bond lengths correlate with (1)Δ DHIECS. PMID:23315885

  17. (13)C/(12)C isotope ratios of organic acids, glucose and fructose determined by HPLC-co-IRMS for lemon juices authenticity.

    PubMed

    Guyon, Francois; Auberger, Pauline; Gaillard, Laetita; Loublanches, Caroline; Viateau, Maryse; Sabathié, Nathalie; Salagoïty, Marie-Hélène; Médina, Bernard

    2014-03-01

    High performance liquid chromatography linked to isotope ratio mass spectrometry via an interface allowing the chemical oxidation of organic matter (HPLC-co-IRMS) was used to simultaneously determine carbon 13 isotope ratio (δ(13)C) of organic acids, glucose and fructose in lime and lemon juices. Because of the significant difference between organic acids and sugars concentrations, the experimental protocol was optimised by applying a "current jump" to the IRMS device. The filament current is increased of 300μA during elution in order to enhance IRMS sensitivity. Then, analysis were performed on 35 lemon and lime fruits from various geographical origins and squeezed in the laboratory. An overall average δ(13)C values of -25.40±1.62‰, -23.83±1.82‰ and -25.67±1.72‰ is found for organic acids mixture mainly made up of citric acid, glucose and fructose, respectively. These authentic samples allowed the definition of a confidence domain to which have been confronted 30 commercial juices (24 "pure juices" and 6 coming from concentrate). Among these 30 samples, 10 present δ(13)C values outside the defined range revealing an added "C4" type organic acids or sugars, addition not specified on the label that is not in agreement with EU regulation. PMID:24176310

  18. Variability in the fractionation of stable isotopes during degradation of two intertidal red algae

    NASA Astrophysics Data System (ADS)

    Hill, Jaclyn M.; McQuaid, Christopher D.

    2009-04-01

    Macroalgae contribute to intertidal food webs primarily as detritus, with unclear implications for food web studies using stable isotope analysis. We examined differences in the thallus parts of two South African rhodophytes ( Gelidium pristoides and Hypnea spicifera) and changes in overall δ13C, δ15N signatures and C:N ratios during degradation in both the field and laboratory. We hypothesized that both degrading macroalgal tissue and macroalgal-derived suspended particulate material (SPM) would show negligible changes in δ13C, but enriched δ15N signatures and lower C:N ratios relative to healthy plants. Only C:N laboratory ratios conformed to predictions, with both species of macroalgae showing decomposition related changes in δ13C and significant depletions in δ15N in both the field and laboratory. In the laboratory, algal tissue and SPM from each species behaved similarly (though some effects were non-significant) but with differing strengths. Gelidium pristoides δ13C increased and C:N ratios decreased over time in tissue and SPM; δ15N became depleted only in SPM. Hypnea spicifera, δ13C, δ15N and C:N ratios all decreased during degradation in both SPM and algae. Over 60 days in the field, δ13C was depleted in both species (1-2‰) and in naturally senescent Gelidium pristoides fronds. δ15N was depleted in Hypnea spicifera (approx. 1‰), while C:N ratios of both species were unaffected. The two species differed in δ13C, δ15N and C:N after degradation, but only in C:N beforehand. We suggest isotope changes in the laboratory mainly reflect microbial effects, while in the field these are combined with leaching due to constant water replenishment and agitation. Differences between these two species in the isotope responses to degradation highlight the difficulty of linking the signature of SPM to its multiple sources.

  19. The δ13C evolution of cave drip water along discreet flow paths in a central Texas cave: Quantifying kinetic isotope fractionation factors

    NASA Astrophysics Data System (ADS)

    Mickler, P. J.; Carlson, P. E.; Banner, J.; Breecker, D.; Stern, L. A.; Baseman, A.

    2015-12-01

    Gaps remain in our understanding of in-cave processes that influence cave water chemistry during speleothem formation. Quantifying environmental controls on the isotopic and chemical evolution of karst groundwater would improve the accuracy of speleothem-based paleoclimate reconstructions. In this study, drip water chemical evolution along flow paths was sampled monthly at two locations in Inner Space Cavern, Texas, over a period of 8 months. In each of the two locations, cave water drips off a stalactite, flows along a flowstone and subsequently drips off a lower stalactite, allowing cave water to be sampled at two points, 1-2 meters apart, along each flow path. The chemical and isotopic evolution of drip water along its flow path shows seasonality, where 1) summer months (high cave-air pCO2) have small variations in δ13C values along the flow paths, high and relatively invariant DIC and Ca values,; and 2) winter months (low cave-air pCO2) generally have large increases in DIC δ13C values along the flow paths, lower DIC and Ca values. The magnitude of the increase in DIC δ13C values along the flow paths, <~1‰ to ~4‰, is controlled by the extent of DIC loss to CO2 degassing and calcite precipitation which is controlled by the pCO2 gradient between drip water and cave air. If the DIC loss is less than 15%, then the evolution of the δ13C value of the DIC reservoir can be modelled using a Rayleigh distillation model and equilibrium fractionation factors between (CO2(g)-HCO3-(aq)) and (CaCO3-HCO3-(aq)). As the loss of the DIC reservoir increases above 15% the DIC δ13C values become progressively higher such that the ɛ (CO2(g)-HCO3-(aq)) values needed to model the observed results change from equilibrium values of ~8‰ to non-equilibrium values up to ~25‰. The variance in magnitude of carbon isotope fractionation during CO2 degassing cannot be attributed to changes in temperature, and thus we infer significant kinetic isotope effects at higher rates of DIC

  20. Modelling of stable isotope fractionation by methane oxidation and diffusion in landfill cover soils

    SciTech Connect

    Mahieu, Koenraad De Visscher, Alex; Vanrolleghem, Peter A.; Van Cleemput, Oswald

    2008-07-01

    A technique to measure biological methane oxidation in landfill cover soils that is gaining increased interest is the measurement of stable isotope fractionation in the methane. Usually to quantify methane oxidation, only fractionation by oxidation is taken into account. Recently it was shown that neglecting the isotope fractionation by diffusion results in underestimation of the methane oxidation. In this study a simulation model was developed that describes gas transport and methane oxidation in landfill cover soils. The model distinguishes between {sup 12}CH{sub 4}, {sup 13}CH{sub 4}, and {sup 12}CH{sub 3}D explicitly, and includes isotope fractionation by diffusion and oxidation. To evaluate the model, the simulations were compared with column experiments from previous studies. The predicted concentration profiles and isotopic profiles match the measured ones very well, with a root mean square deviation (RMSD) of 1.7 vol% in the concentration and a RMSD of 0.8 per mille in the {delta}{sup 13}C value, with {delta}{sup 13}C the relative {sup 13}C abundance as compared to an international standard. Overall, the comparison shows that a model-based isotope approach for the determination of methane oxidation efficiencies is feasible and superior to existing isotope methods.

  1. Investigation of tubular handling of bicarbonate in man. A new approach utilizing stable carbon isotope fractionation.

    PubMed Central

    Burbea, Z H; Luz, B; Lazar, B; Winaver, J; Better, O S

    1983-01-01

    Two alternative mechanisms have been proposed for tubular reabsorption of bicarbonate: (a) H+ secretion and CO2 reabsorption and (b) direct reabsorption of HCO-3. In an attempt to differentiate between the two mechanisms, the present study utilized the natural abundance of stable carbon isotopes (13C, 12C) in the urinary total CO2. This novel methodology used mass spectrometric analysis of 13C/12C ratios in urinary total CO2 under normal conditions and during acetazolamide treatment. Blood and respiratory CO2 were analyzed to yield reference values. The results demonstrate that alkaline urine is preferentially enriched with 13C relative to the blood. It is suggested that this fractionation results from reaction out of isotopic equilibrium in which HCO-3 converts to CO2 during the reabsorption process in the distal nephron. The presence of carbonic anhydrase in the proximal nephron results in rapid isotopic exchange between CO2 and HCO-3 and keeps them in isotopic equilibrium. The ratio of urinary 13C/12C increases strikingly after acetazolamide administration and consequent inhibition of carbonic anhydrase in the proximal tubule. Although it is possible that in the latter case high HCO-3 generates the CO2 (ampholyte effect), the isotope fractionation indicates that CO2 rather than HCO-3 is reabsorbed. In contrast, at low urinary pH and total CO2 values, the carbon isotope composition approaches that of blood CO2. This indicates rapid CO2 exchange between urine and blood, through luminal membrane highly permeable to CO2. These results could be anticipated by a mathematical model constructed to plot 13C concentration of urinary total CO2. It is concluded that the mechanism of HCO-3 reclamation in man (and, by inference, in other mammals as well) works by conversion of HCO-3 to CO2 and reabsorption of CO2. PMID:6417168

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    PubMed

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

    2016-01-01

    Tibetan Plateau is located at a mountain region isolated from direct anthropogenic sources. Mercury concentrations and stable isotopes of carbon, nitrogen, and mercury were analyzed in sediment and biota for Nam Co and Yamdrok Lake. Biotic mercury concentrations and high food web magnification factors suggested that Tibetan Plateau is no longer a pristine site. The primary source of methylmercury was microbial production in local sediment despite the lack of direct methylmercury input. Strong ultraviolet intensity led to extensive photochemical reactions and up to 65% of methylmercury in water was photo-demethylated before entering the food webs. Biota displayed very high Δ(199)Hg signatures, with some highest value (8.6%) ever in living organisms. The δ(202)Hg and Δ(199)Hg in sediment and biotic samples increased with trophic positions (δ(15)N) and %methylmercury. Fish total length closely correlated to δ(13)C and Δ(199)Hg values due to dissimilar carbon sources and methylmercury pools in different living waters. This is the first mercury isotope study on high altitude lake ecosystems that demonstrated specific isotope fractionations of mercury under extreme environmental conditions. PMID:27151563

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

    PubMed Central

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

    2016-01-01

    Tibetan Plateau is located at a mountain region isolated from direct anthropogenic sources. Mercury concentrations and stable isotopes of carbon, nitrogen, and mercury were analyzed in sediment and biota for Nam Co and Yamdrok Lake. Biotic mercury concentrations and high food web magnification factors suggested that Tibetan Plateau is no longer a pristine site. The primary source of methylmercury was microbial production in local sediment despite the lack of direct methylmercury input. Strong ultraviolet intensity led to extensive photochemical reactions and up to 65% of methylmercury in water was photo-demethylated before entering the food webs. Biota displayed very high Δ199Hg signatures, with some highest value (8.6%) ever in living organisms. The δ202Hg and Δ199Hg in sediment and biotic samples increased with trophic positions (δ15N) and %methylmercury. Fish total length closely correlated to δ13C and Δ199Hg values due to dissimilar carbon sources and methylmercury pools in different living waters. This is the first mercury isotope study on high altitude lake ecosystems that demonstrated specific isotope fractionations of mercury under extreme environmental conditions. PMID:27151563

  5. In-situ biodegradation of tetrachloroethene and trichloroethene in contaminated aquifers monitored by stable isotope fractionation.

    PubMed

    Vieth, A; Müller, J; Strauch, G; Kästner, M; Gehre, M; Meckenstock, R U; Richnow, H H

    2003-06-01

    Stable carbon isotope analysis of tetrachloroethene (PCE) and trichloroethene (TCE) was applied to evaluatenatural attenuation processes in the upper Quaternary and lower Tertiary aquifer in the area of a former dry-cleaning plant located in Leipzig, Germany. Groundwater samples were taken during one monitoring campaign in 2001. The 13C enrichment in contaminants along the water flow path suggested that both, PCE and TCE were degraded in the Quaternary aquifer. The enrichment of 13C in the residual PCE fraction and an isotope fractionation factor from laboratory experiments were used to calculate the extent of biodegradation in the Quatemary aquifer. These calculations indicated that a major portion of PCE was biodegraded in the course of the plume. In the Tertiary aquifer the carbon isotope ratios of PCE and TCE indicated that the decreasing concentrations of these contaminants were probably not caused by microbial processes. PMID:12872803

  6. Versatile inlet system for on-line compound-specific deltaD and delta13C gas chromatography-oxidation/reduction-isotope ratio mass spectrometry analysis of gaseous mixtures.

    PubMed

    Henning, Mark; Strapoć, Dariusz; Lis, Grzegorz P; Sauer, Peter; Fong, Jon; Schimmelmann, Arndt; Pratt, Lisa M

    2007-01-01

    Compound-specific deltaD and delta13C analyses of gas mixtures are useful indicators of geochemical and environmental factors. However, the relative concentrations of individual components in gas mixtures (e.g., H2, CO2, methane, ethane, propane, i-butane, n-butane) may vary over several orders of magnitude. The determination of hydrogen and carbon compound-specific stable isotope ratios requires that the hydrogen and carbon dioxide produced from each separated component has a concentration adjusted to match the dynamic range of the stable isotope mass spectrometer. We present a custom-built gas sampling and injection system (GASIS) linked with a Delta Plus XP mass spectrometer that provides flexibility, ease of operation, and economical use of small gas samples with wide ranges of analyte concentrations. The overall on-line GC-ox/red-IRMS (Gas Chromatography - oxidation/reduction - Isotope Ratio Mass Spectrometry) system consists of (i) a customized GASIS inlet system and (ii) two alternative reactors, namely an oxidative Cu-Ni-Pt reactor at 950 degrees C for production of CO2 and a reductive graphitized Al2O3 reactor at 1420 degrees C for production of H2. In addition, the system is equipped with (iii) a liquid nitrogen spray-cooling unit for cryo-GC-focusing at -20 degrees C, and (iv) a Nafion dryer for removal of water vapor from product CO2. The three injection loops of the GASIS inlet allow flexibility in the volume of injected analyte gas (e.g., from 0.06 to 500 microL) in order to measure reproducible deltaD and delta13C values for gases at concentrations ranging from 100% down to 10 ppm. We calibrate our GC-ox/red-IRMS system with two isotopically distinct methane references gases that are combusted off-line and characterized using dual-inlet IRMS. PMID:17577874

  7. Experimental assessment of environmental influences on the stable isotopic composition of Daphnia pulicaria and their ephippia

    NASA Astrophysics Data System (ADS)

    Schilder, J.; Tellenbach, C.; Möst, M.; Spaak, P.; van Hardenbroek, M.; Wooller, M. J.; Heiri, O.

    2015-02-01

    The stable isotopic composition of fossil resting eggs (ephippia) of Daphnia spp. is being used to reconstruct past environmental conditions in lake ecosystems. However, the underlying assumption that the stable isotopic composition of the ephippia reflects the stable isotopic composition of the parent Daphnia, of their diet and of the environmental water have yet to be confirmed in a controlled experimental setting. We performed experiments with Daphnia pulicaria cultures, which included a control treatment conducted at 12 °C in filtered lake water and with a diet of fresh algae, and three treatments in which we manipulated the stable carbon isotopic composition (δ13C value) of the algae, stable oxygen isotopic composition (δ18O value) of the water, and the water temperature, respectively. The stable nitrogen isotopic composition (δ15N value) of the algae was similar for all treatments. At 12 °C, differences in algal δ13C values and in δ18O values of water are reflected in those of Daphnia. The differences between ephippia and Daphnia stable isotope ratios were similar in the different treatments (δ13C: + 0.2 ± 0.4‰ (SD); δ15N: -1.6 ± 0.4‰; δ18O: -0.9 ± 0.4‰) indicating that changes in dietary δ13C and δ18O values of water are passed on to these fossilizing structures. A higher water temperature (20 °C) resulted in lower δ13C values in Daphnia and ephippia than in the other treatments with the same food source and in a minor change in the difference between δ13C values of ephippia and Daphnia (to -1.3 ± 0.3‰). This may have been due to microbial processes or increased algal respiration rates in the experimental containers, which may not affect Daphnia in natural environments. There was no significant difference in the offset between δ18O and δ15N values of ephippia and Daphnia between the 12 °C and 20 °C treatments, but the δ18O values of Daphnia and ephippia were on average 1.2‰ lower at 20 °C compared with 12 °C. We conclude

  8. Tungsten Stable Isotope Compositions of Ferromanganese Crusts

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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

  9. 13C NMR chemical shift correlations in application of “tool of increasing electron demand” to stable long-lived carbocations: Comprehensive evaluation*

    PubMed Central

    Olah, George A.; Berrier, Arthur L.; Prakash, G. K. Surya

    1981-01-01

    The reliability of 13C NMR chemical shift correlations in the application of the “tool of increasing electron demand” to stable long-lived carbocationic systems is demonstrated by a comprehensive analysis of 22 stable aryl-substituted carbocationic systems. The observation of slopes of less than unity in such chemical shift correlations for several cationic systems has been attributed to additional charge delocalizing mechanisms present in the system (such as homoallylic, cyclopropyl, and π conjugations). The onset of nonclassical σ-delocalization in 2-aryl-2-norbornyl cations with electron withdrawing-substituents previously observed was further verified by using σC+ substituent constants. Difficulties in relating the CαNMR shifts in different carbocationic systems are also discussed. PMID:16593000

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    As metagenomics increases our insight into microbial community diversity and metabolic potential, new approaches are required to determine the biogeochemical expression of this potential within ecosystems. Because stable isotopic analysis of the major bioactive elements (C, N) has been used historically to map flows of substrates and energy among macroscopic food webs, similar principles may apply to microbes. To address this challenge, we have developed a new analytical approach called Protein Stable Isotope Fingerprinting (P-SIF). P-SIF generates natural stable isotopic fingerprints of microbial individual or community proteomes. The main advantage of P-SIF is the potential to bridge the gap between diversity and function, thereby providing a window into the "black box" of environmental microbiology and helping to decipher the roles of uncultivated species. Our method implements a three-way, orthogonal scheme to separate mixtures of whole proteins into subfractions dominated by single or closely-related proteins. Protein extracts first are isoelectrically focused in a gel-free technique that yields 12 fractions separated over a gradient of pH 3-10. Each fraction then is separated by size-exclusion chromatography into 20 pools, ranging from >100kD to ~10kD. Finally, each of these pools is subjected to HPLC and collected in 40 time-slices based on protein hydrophobicity. Theoretical calculation reveals that the true chromatographic resolution of the total scheme is 5000, somewhat less than the 9600 resulting fractions. High-yielding fractions are subjected to δ13C analysis by spooling-wire microcombustion irMS (SWiM-irMS) optimized for samples containing 1-5 nmol carbon. Here we will present the method, results for a variety of pure cultures, and preliminary data for a sample of mixed environmental proteins. The data show the promise of this method for unraveling the metabolic complexity hidden within microbial communities.

  11. Carbon stable isotope composition of DNA isolated from an incipient paleosol

    NASA Astrophysics Data System (ADS)

    Jahren, A. Hope; Kelm, Kellie; Wendland, Beverly; Petersen, Gitte; Seberg, Ole

    2006-05-01

    We determined the carbon isotope13C) value of double-stranded DNA (dsDNA) isolated from the organic horizons of a Delaware soil that is actively being covered by an encroaching sand dune. The soil belongs to a Nymphaea odorata Ait. (water lily) wetland, and we regard its active acquisition of a thick (˜24 cm) surface mantle to embody the process of paleopedogenesis; therefore, we have termed it an “incipient paleosol.” In this study, we compared the δ13C value of paleosol dsDNA to the bulk δ13C value of N. odorata, as well as to the δ13C value of plants that had colonized the surface mantle. The isotopic offset between paleosol δ13CdsDNA and N. odorata δ13Ctissue was identical to the relationship between δ13CdsDNA and δ13Ctissue for tracheophytes, which we had previously determined. In contrast, the isotopic offset between paleosol δ13CdsDNA and the δ13Ctissue of plants colonizing the surface mantle differed from this relationship by as much as 4‰. Similarly, the δ13C value of bulk paleosol organic matter was extremely heterogeneous and varied across 6‰. All paleosol DNA polymerase chain reaction (PCR) products produced clear, sharp, 350 base-pair (bp) fragments of rbcL, a gene shared by all photosynthetic organisms. These results open the exciting possibility that stable isotope analysis of dsDNA isolated from paleosol organic matter can be used to infer the δ13C value of the plant that dominated the nucleic acid contribution.

  12. Stable carbon isotope composition of secondary organic aerosol from β-pinene oxidation

    NASA Astrophysics Data System (ADS)

    Fisseha, Rebeka; Spahn, Holger; Wegener, Robert; Hohaus, Thorsten; Brasse, Gregor; Wissel, Holger; Tillmann, Ralf; Wahner, Andreas; Koppmann, Ralf; Kiendler-Scharr, Astrid

    2009-01-01

    A chamber study was carried out to investigate the stable carbon isotopic composition (δ13C) of secondary organic aerosol (SOA) formed from ozonolysis of β-pinene. β-Pinene (600 ppb) with a known δ13C value (-30.1‰) and 500 ppb ozone were injected into the chamber in the absence of light and the resulting SOA was collected on preheated quartz fiber filters. Furthermore, δ13C values of the gas-phase β-pinene and one of its oxidation products, nopinone, were measured using a gas chromatograph coupled to an isotope ratio mass spectrometer (GC-IRMS). β-Pinene was progressively enriched with the heavy carbon isotope due to the kinetic isotope effect (KIE). The KIE of the reaction of β-pinene with ozone was measured to be 1.0026 ? 2.6 ± 1.5‰). The δ13C value of total secondary organic aerosol was very similar to that of its precursor (average = -29.6 ± 0.2‰) independent of experiment time. Nopinone, one of the major oxidation products of β-pinene, was found in both the gas and aerosol phases. The gas-phase nopinone was heavier than the initial β-pinene by 1.3‰ but lighter than the corresponding aerosol-phase nopinone. On average, the gas-phase nopinone was lighter by 2.3‰ than the corresponding aerosol-phase nopinone. The second product found in the SOA was detected as acetone, but it desorbed from the filter at a higher temperature than nopinone, which indicates that it is a pyrolysis product. The acetone showed a much lower δ13C (-36.6‰) compared to the initial β-pinene δ13C.

  13. Stable isotope methods: The effect of gut contents on isotopic ratios of zooplankton

    NASA Astrophysics Data System (ADS)

    Hill, J. M.; McQuaid, C. D.

    2011-05-01

    In the past decade there has been an increased awareness of the potential for methodological bias resulting from multiple pre-analytical procedures in foodweb interpretations based on stable isotope techniques. In the case of small organisms, this includes the effect of gut contents on whole body signatures. Although gut contents may not reflect actual assimilation, their carbon and nitrogen values will be isotopically lighter than after the same material has been assimilated. The potential skewing of isotopic ratios in whole organism samples is especially important for aquatic environments as many studies involve trophic relationships among small zooplankton. This is particularly important in pelagic waters, where herbivorous zooplankton comprise small taxa. Hence this study investigated the effect of gut contents on the δ13C and δ15N ratios of three size classes of zooplankton (1.0-2.0, 2.0-4.0 and >4.0 mm) collected using bongo net tows in the tropical waters of the south-west Indian Ocean. Animals were collected at night, when they were likely to be feeding, sieved into size classes and separated into genera. We focused on Euphausia spp which dominated zooplankton biomass. Three treatment types were processed: bulk animals, bulk animals without guts and tail muscle from each size class at 10 bongo stations. The δ15N ratios were influenced by zooplankton size class, presumably reflecting ontogenetic changes in diet. ANOVA post hoc results and correlations in δ15N signatures among treatments suggest that gut contents may not affect overall nitrogen signatures of Euphausia spp., but that δ13C signatures may be significantly altered by their presence. Carbon interpretations however, were complicated by potential effects of variation in chitin, lipids and metabolism among tissues and the possibility of opportunistic omnivory. Consequently we advocate gut evacuation before sacrifice in euphausiids if specific tissue dissection is impractical and recommend

  14. Determination of the 13C/12C ratio of ethanol derived from fruit juices and maple syrup by isotope ratio mass spectrometry: collaborative study.

    PubMed

    Jamin, Eric; Martin, Frédérique; Martin, Gilles G

    2004-01-01

    A collaborative study of the carbon-13 isotope ratio mass spectrometry (13C-IRMS) method based on fermentation ethanol for detecting some sugar additions in fruit juices and maple syrup is reported. This method is complementary to the site-specific natural isotope fractionation by nuclear magnetic resonance (SNIF-NMR) method for detecting added beet sugar in the same products (AOAC Official Methods 995.17 and 2000.19), and uses the same initial steps to recover pure ethanol. The fruit juices or maple syrups are completely fermented with yeast, and the alcohol is distilled with a quantitative yield (>96%). The carbon-13 deviation (delta13C) of ethanol is then determined by IRMS. This parameter becomes less negative when exogenous sugar derived from plants exhibiting a C4 metabolism (e.g., corn or cane) is added to a juice obtained from plants exhibiting a C3 metabolism (most common fruits except pineapple) or to maple syrup. Conversely, the delta13C of ethanol becomes more negative when exogenous sugar derived from C3 plants (e.g., beet, wheat, rice) is added to pineapple products. Twelve laboratories analyzed 2 materials (orange juice and pure cane sugar) in blind duplicate and 4 sugar-adulterated materials (orange juice, maple syrup, pineapple juice, and apple juice) as Youden pairs. The precision of that method for measuring delta13C was similar to that of other methods applied to wine ethanol or extracted sugars in juices. The within-laboratory (Sr) values ranged from 0.06 to 0.16%o (r = 0.17 to 0.46 percent per thousand), and the among-laboratories (SR) values ranged from 0.17 to 0.26 percent per thousand (R = 0.49 to 0.73 percent per thousand). The Study Directors recommend that the method be adopted as First Action by AOAC INTERNATIONAL. PMID:15287660

  15. Synthesizing the Use of Carbon Isotope (14C and 13C) Approaches to Understand Rates and Pathways for Permafrost C Mobilization and Mineralization

    NASA Astrophysics Data System (ADS)

    Estop-Aragones, C.; Olefeldt, D.; Schuur, E.

    2015-12-01

    To better understand the permafrost carbon (C) feedback it is important to synthesize our current knowledge, and knowledge gaps, of how permafrost thaw can cause in situ mineralization or downstream mobilization of aged soil organic carbon (SOC) and the rate of this release. This potential loss of old SOC may occur via gaseous flux of CO2 and CH4 exchanged between soil and the atmosphere and via waterborne flux as DOC, POC (and their subsequent decomposition and release to the atmosphere). Carbon isotope (14C and 13C) approaches have been used to estimate both rates and pathways for permafrost C mobilization and mineralization. Radiocarbon (14C) has been used to estimate the contribution of aged C to overall respiration or waterborne C export. We aim to contrast results from radiocarbon studies, in order to assess differences between ecosystems (contrasting wet and dry ecosystems), thaw histories (active layer deepening or thermokarst landforms), greenhouse gas considered (CO2 and CH4) and seasons. We propose to also contrast methodologies used for assessing the contribution of aged C to overall C balance, and include studies using 13C data. Biological fractionation of 13C during both uptake and decomposition has been taken advantage of both in order to aid the interpretation of 14C data and on its own to assess sources and mineralization pathways. For example, 13C data has been used to differentiate between CH4 production pathways, and the relative contribution of anaerobic CO2 production to overall respiration. Overall, carbon isotope research is proving highly valuable for our understanding of permafrost C dynamics following thaw, and there is a current need to synthesize the available literature.

  16. Food sources of macro-invertebrates in an important mangrove ecosystem of Vietnam determined by dual stable isotope signatures

    NASA Astrophysics Data System (ADS)

    Tue, Nguyen Tai; Hamaoka, Hideki; Sogabe, Atsushi; Quy, Tran Dang; Nhuan, Mai Trong; Omori, Koji

    2012-08-01

    Dual stable isotope signatures (δ13C and δ15N) were applied to determine the contribution of mangrove materials and other organic carbon sources to the invertebrate community in an ecologically important mangrove ecosystem of Vietnam. We have analyzed 181 specimens of 30 invertebrate species and found δ13C and δ15N ranging from - 14.5 to - 26.8‰ and from 1.3 to 12.1‰, respectively. From taxa measured for stable isotopes, polychaete, gastropods, bivalves, and grapsid crabs living in mangrove forest showed relative low δ13C values, while fiddler crabs inhabiting in the land-water ecotone showed the highest δ13C values. The δ13C showed that just a few mangrove inhabitants directly relied on the mangrove materials. The wide ranges of δ13C and δ15N signatures indicated that the invertebrates utilized heterogeneous diets, comprising benthic microalgae, marine phytoplankton, particulate organic matter, sediment organic matter, mangrove detritus, and meiofauna and rotten animal tissues as the supplemental nutrient food sources. Moreover, the significant correlation between δ13C values and body sizes of invertebrates showed that snails Littoraria melanostoma and Terebralia sulcata, bivalve Glauconome virens, and portunid crab Scylla serrata exhibited ontogenetic shifts in diets. The present study showed that adjacent habitats such as tidal flat and mangrove creeks seem to contribute an important microalgal food resource for invertebrates and highlighted the need for conservations of mangrove forests and the adjacent habitats.

  17. Stable isotopic analyses in paleoclimatic reconstruction

    SciTech Connect

    Wigand, P.E.

    1995-09-01

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

  18. Quantifying uncertainty in stable isotope mixing models

    SciTech Connect

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

    2015-05-19

    Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, SIAR [Parnell et al., 2010] a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ15N and δ18O) but all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the

  19. Quantifying uncertainty in stable isotope mixing models

    DOE PAGESBeta

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

    2015-05-19

    Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, SIAR [Parnell et al., 2010] a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ15N and δ18O) but all methods testedmore » are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated

  20. Determination of methanogenic pathways through carbon isotope13C) analysis for the two-stage anaerobic digestion of high-solids substrates.

    PubMed

    Gehring, Tito; Klang, Johanna; Niedermayr, Andrea; Berzio, Stephan; Immenhauser, Adrian; Klocke, Michael; Wichern, Marc; Lübken, Manfred

    2015-04-01

    This study used carbon isotope (δ(13)C)-based calculations to quantify the specific methanogenic pathways in a two-stage experimental biogas plant composed of three thermophilic leach bed reactors (51-56 °C) followed by a mesophilic (36.5 °C) anaerobic filter. Despite the continuous dominance of the acetoclastic Methanosaeta in the anaerobic filter, the methane (CH4) fraction derived from carbon dioxide reduction (CO2), fmc, varied significantly over the investigation period of 200 days. At organic loading rates (OLRs) below 6.0 gCOD L(-1) d(-1), the average fmc value was 33%, whereas at higher OLRs, with a maximum level of 17.0 gCOD L(-1) d(-1), the fmc values reached 47%. The experiments allowed for a clear differentiation of the isotope fractionation related to the formation and consumption of acetate in both stages of the plant. Our data indicate constant carbon isotope fractionation for acetate formation at different OLRs within the thermophilic leach bed reactors as well as a negligible contribution of homoacetogenesis. These results present the first quantification of methanogenic pathway (fmc values) dynamics for a continually operated mesophilic bioreactor and highlight the enormous potential of δ(13)C analysis for a more comprehensive understanding of the anaerobic degradation processes in CH4-producing biogas plants. PMID:25741999

  1. A new laser spectrometer for measurements of the carbon isotope ratio (δ13C) of methane in air and applications to ice core studies

    NASA Astrophysics Data System (ADS)

    Lee, J. E.; Brook, E.; Dong, F.; Gupta, M.

    2012-12-01

    Methane is the second most important anthropogenic greenhouse gas contributing to global climate change, and yet its sources and sinks are still poorly understood. Isotopic ratios of methane released to the atmosphere depend on the isotopic composition of the source and fractionation by sink processes. Analysis of isotopic compositions can provide further understanding of methane source strength and location. Traditional measurements by mass spectrometry are laborious and not easily adaptable to new continuous gas extraction methodologies. Recent technological advances have reduced the amount of methane necessary for precise measurements of δ13C in methane by laser spectrometry to a practical sample size for ice core studies. We present a new laser-based analyzer for measurement of δ13C in methane that requires less than 6 μmol of CH4. Current precision is better than ±0.5‰ (1σ, 100 seconds) on dry air with [CH4]= 2ppm. The sensor is operable in either discrete or continuous sampling modes allowing for continuous measurement of gas sample exhausted from other analyzers. Detailed performance characteristics and tests will be discussed at the meeting.

  2. Deciphering Ecohydrological Interactions Using Stable Isotopes

    NASA Astrophysics Data System (ADS)

    McDonnell, J.; Evaristo, J. A.; Jasechko, S.

    2014-12-01

    Deciphering the nature of ecohydrological interconnections and scaling that knowledge gained at single points to watersheds is challenging. One tool that that has proved useful in this regard is stable isotope tracing. Single isotope studies have been used recently to quantify landuse change effects on streamflow source apportionment and ecological effects on transit time distributions of water at the catchment scale. However, most work to date has assumed that plant transpiration, groundwater recharge and streamflow are all sourced or mediated by the same well mixed reservoir—the soil. Recent work in Oregon and Mexico has shown evidence of ecohydrological separation, whereby different subsurface compartmentalized pools of water supply either plant transpiration fluxes or the combined fluxes of groundwater recharge and streamflow. However, these findings have not yet been widely tested. Here we assemble the first dual isotope database for δ2H and δ18O extracted from 47 globally-distributed stable isotopic datasets. We use these data to test the ecohydrological separation hypothesis. We combine this dual isotope dataset with global precipitation, streamwater, groundwater and soil water datasets. Our results show that precipitation, streamwater and groundwater from the 47 sites plot approximately along the δ2H/δ18O slope of eight, suggesting that local precipitation inputs supply streamwater and groundwater. Soil waters extracted from the 47 studies plot below the regression of local streamwater and groundwater with a slope of 6.6±0.05 ‰. Local plant xylem waters from our matched dataset plot on a slope 6.6±0.07 ‰ consistent with local soil waters. The tight association of soil water slopes and not that of local groundwater or streamflow suggests that plants use soil water that does not itself contribute to groundwater recharge or stream water. This ubiquity of subsurface water compartmentalization is surprising and has important implications for how we

  3. Stable carbon isotope ratios in Astrangia danae : evidence for algal modification of carbon pools used in calcification

    NASA Astrophysics Data System (ADS)

    Cummings, C. E.; McCarty, H. B.

    1982-06-01

    Stable carbon isotope ratios have been measured in skeletons of the temperature shallow water scleractinian coral, Astrangia danae. δ13C values ranging from -5.42 to -7.30%. revealed the expected depletion of 13C in skeletal carbonate relative to sea water bicarbonate. Differences among the ratios could not be attributed to collection site and were not correlated to skeletal morphology. Values of δ13C were directly related to zooxanthellae density for all colonies, so that as zooxanthellae concentration increased, δ13C valued increased. Colonies maintained under high temperature conditions were offset from the normal, exhibiting ratios less enriched in 13C than similar colonies from natural conditions. These trends supported the models of Weber and Goreau in which the carbon pools used in calcification are modified by algal photosynthesis. Direct evidence of physiological differences between symbiotic and asymbiotic colonies of A. danae has also been provided.

  4. 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.

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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

  5. Developing stable isotopic records from organic material preserved in speleothems

    NASA Astrophysics Data System (ADS)

    Blyth, A.; Baker, A.

    2011-12-01

    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

  6. Laboratory measurement of temperature dependent 13C and D kinetic isotope effect in the reaction of CH4 oxidation by O(1D)

    NASA Astrophysics Data System (ADS)

    Shen, Linhan; Bui, Thinh Q.; Chen, Pin; Okumura, Mitchio

    2014-11-01

    Martian atmospheric methane (CH4) concentrations observed from satellite orbiter and Earth based telescopes have shown significant time and spatial variations. Recent MSL measurements observed very low methane concentrations (0.18 ± 0.67 ppbv). In order to reconcile these findings, a search of missing methane sinks is needed. In this study, we investigated the kinetic isotope effect (KIE) of methane oxidation reaction by O(1D) as a function of temperature, which will provide an important constraint to the loss of methane. The KIE of major methane isotopologues (13CH4 and 12CH3D) are measured as a function of temperature. The experiments were carried out by photolyzing a mixture of N2O, isotope enriched methane, and He at 193 nm in a temperature controlled cell between 155 K and 300 K. The N2O molecules were used as an O(1D) source, while He was used to collisionally quench translationally hot O(1D) radicals. The concentrations of all major methane isotopologues before and after photolysis were analyzed using a frequency stabilized cavity ringdown (FS-CRDS) spectrometer. The spectrometer employs coupling of two orthogonally polarized cw lasers into a ringdown cavity for simultaneous spectral measurements over the full wavelength range of 1.45 - 1.65 µm and is capable of measuring isotopes of methane of enriched samples to a very high precision (D < 0.03% and 13C < 0.01%). We measured for the first time the D-KIE and 13C-KIE at temperatures relative to the Martian conditions. Our measurements observed D-KIE(155 K) = 1.133(20), and 13C-KIE(115 K) = 1.149(22).

  7. Stable carbon isotopic compositions of organic acids in total suspended particles and dusts from Guangzhou, China

    NASA Astrophysics Data System (ADS)

    Ma, Shexia; Peng, Ping'an; Song, Jianzhong; Zhao, Jinping; He, Lulu; Sheng, Guoying; Fu, Jiamo

    2010-10-01

    Stable carbon isotopic compositions of individual organic acids were determined in total suspended particles and dusts from Guangzhou. The δ 13C values of high molecular weight n-alkanoic acids (C 20-C 28) varied from -34.1‰ to -32.4‰ and tended to be heavier in summer and lighter in winter. These δ 13C values indicate that high molecular weight n-alkanoic acids were derived mainly from emission by C 3 plants. Reduced biological synthesis of high molecular weight n-alkanoic acids in winter may be the reason for the light carbon isotopic composition. The δ 13C values of low molecular weight n-alkanoic acids (C 10-C 18) changed from -31.7‰ to -30.3‰ and exhibited a reverse seasonal trend, i.e., heavier in winter and lighter in summer. Slightly heavier δ 13C values of low molecular weight n-alkanoic acids than those of high molecular weight n-alkanoic acids suggested that they may be emitted from blended sources, e.g., anthropogenic sources and vegetation waxes. Lighter δ 13C values in summer may be attributed to relatively low anthropogenic sources and high botanic sources in summer. Dicarboxylic acids and aromatic acids have been proposed as secondary products from photochemical degradation. The average δ 13C values of dicarboxylic acids and aromatic acids were heavier, and ranged from -25.2‰ to -22.9‰ and from -30.0‰ to -27.6‰, respectively. Both dicarboxylic acids and aromatic acids displayed the same temporal variations in the δ 13C values, i.e., negative δ 13C in the summer samples and positive in the winter samples, which may be controlled by photochemical reactions; they are generally severe in winter in Guangzhou under the monsoon weather system. The heaviest δ 13C values were observed in dicarboxylic acids, indicating that dicarboxylic acids were formed by fast and more complete oxidation reactions. These results indicate that the stable carbon isotopic composition of organic acids may provide important information about sources and

  8. Stable carbon isotopic evidence for differences in the dietary origin of bone cholesterol, collagen and apatite: implications for their use in palaeodietary reconstruction

    NASA Astrophysics Data System (ADS)

    Jim, Susan; Ambrose, Stanley H.; Evershed, Richard P.

    2004-01-01

    Rats were raised on a variety of isotopically controlled diets comprising 20% C 3, C 4 or marine protein and C 3 and/or C 4 non-protein or energy (i.e. sucrose, starch and oil) macronutrients. Compound specific stable carbon isotope13C) analysis was performed on the cholesterol isolated from the diet ( n=7 ) and bone ( n=15 ) of these animals and the values compared with bulk δ 13C measurements of bone collagen and apatite. The dietary signals reflected by these three bone biochemical components were investigated using linear regression analysis. δ 13C values of bone cholesterol were shown to reflect whole diet δ 13C values, collagen to reflect mainly dietary protein values and apatite to reflect whole diet values. Further correlations between dietary protein-to-energy spacings (Δ 13C prot-engy = δ 13C protein - δ 13C energy) and whole diet-to-bone component fractionations (Δ 13C bcomp- wdiet = δ 13C bone component - δ 13C whole diet) indicates that for hypothetical diets where protein δ 13C values are equal to energy values, fractionations between whole diet and bone biochemical fractions are -3.3‰ for cholesterol, +5.4‰ for collagen and +9.5‰ for apatite. Moreover, the narrow range of variation observed in apatite-to-cholesterol spacings (Δ 13C apat- bchol ) suggests that cholesterol δ 13C values can potentially also be used as an independent test for the isotopic integrity of apatite δ 13C values. These insights into bone cholesterol, collagen and apatite dietary signals, diet-to-bone fractionations and bone component-to-bone component spacings provide the basis for more accurate interpretations of the dietary behaviour of archaeological populations and food webs when the δ 13C analysis of bone is employed.

  9. Correlation between multielement stable isotope ratio and geographical origin in Peretta cows' milk cheese.

    PubMed

    Manca, G; Franco, M A; Versini, G; Camin, F; Rossmann, A; Tola, A

    2006-03-01

    The aim of this study was to characterize the isotopic composition and protect "Peretta" cows' milk cheese, a typical product of Sardinia, against other cheeses of the same appearance sold under the same name, but made of raw materials from northern Europe. The study was concerned with 3 types of cheese: those produced in local dairies from milk from free-grazing or pasture-grazing cows in Sardinia (local dairy product), cheeses made on an industrial scale from milk produced by intensive farming in Sardinia (factory cheese), and cheeses made with raw materials imported from other countries (imported product). To distinguish the Sardinian cheeses from the imported product, the stable isotope ratios 13C/12C, 15N/14N, D/H, 34S/32S, and (18)O/(16)O were used. Determination of the isotopic data delta13C, delta15N, delta2H, and delta34S was performed in the casein fraction, whereas delta(18)O and delta13C were determined in the glycerol fraction. Measurements were performed by isotope ratio mass spectrometry. A comparison between mean values of the isotope ratios by statistical analysis (ANOVA and Tukey's test) showed that the greatest difference between the 3 types of cheese (local dairy, factory, and imported products) was in the 13C/12C, 34S/32S, and (18)O/(16)O isotope ratios. In the other parameters, either no differences (delta15N) or minimal differences (delta2H) were found. Evaluation of the data by multivariate statistical analysis (principal component analysis and hierarchical cluster analysis) revealed that the isotope characteristics of the factory products were similar to those of the cheeses produced from imported raw materials, whereas a difference was found between the local dairy-produced cheeses and the products in the other 2 categories. PMID:16507675

  10. Evaluation of on-line pyrolysis coupled to isotope ratio mass spectrometry for the determination of position-specific (13)C isotope composition of short chain n-alkanes (C6-C12).

    PubMed

    Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro

    2016-06-01

    We measured (13)C intramolecular isotopic composition of commercially available short-chain hydrocarbons (n-C6-n-C12) using (13)C-NMR. Results show that the main variation is between the terminal and the sub-terminal C-atom positions. Site-preference (difference in δ(13)C values between terminal and sub-terminal C-atom positions) among all the samples varies between -12.2‰ and +8.4‰. Comparison of these results with those obtained using on-line pyrolysis coupled with GC-C-IRMS show that the thermal cracking of hydrocarbons occurs with a good isotopic fidelity between terminal and sub-terminal C-atom positions of the starting material and the related pyrolysis products (methane and ethylene). On-line pyrolysis coupled with GC-C-IRMS can thus be used for tracing hydrocarbons biogeochemical processes. PMID:27130103

  11. Application of δ13C and δ15N isotopic signatures of organic matter fractions sequentially separated from adjacent arable and forest soils to identify carbon stabilization mechanisms

    NASA Astrophysics Data System (ADS)

    Kayler, Z. E.; Kaiser, M.; Gessler, A.; Ellerbrock, R. H.; Sommer, M.

    2011-03-01

    Identifying the chemical mechanisms behind soil carbon bound in organo-mineral complexes is necessary to determine the degree to which soil organic carbon is stabilized belowground. We used the δ13C and δ15N isotopic signatures from two organic matter (OM) fractions from soil to identify the likely binding mechanisms involved. We used OM fractions hypothesized to contain carbon stabilized through organo-mineral complexes: (1) OM separated chemically with sodium pyrophosphate (OM(PY)) and (2) OM stabilized in microstructures found in the chemical extraction residue (OM(ER)). Furthermore, because the OM fractions were separated from five different soils with paired forest and arable land use histories, we could address the impact of land use change on carbon binding and processing mechanisms within these soils. We used partial least squares regression to analyze patterns in the isotopic signature of OM with established proxies of different binding mechanisms. Parsing soil OM into different fractions is a systematic method of dissection, however, we are primarily interested in how OM is bound in soil as a whole, requiring a means of re-assembly. Thus, we implemented the recent zonal framework described by Kleber et al. (2007) to relate our findings to undisturbed soil. The δ15N signature of OM fractions served as a reliable indicator for microbial processed carbon in both arable and forest land use types. The δ13C signature of OM fractions in arable sites did not correlate well with proxies of soil mineral properties while a consistent pattern of enrichment was seen in the δ13C of OM fractions in the forest sites. We found a significant difference in δ13C of pooled OM fractions between the forest and arable land use type although it was relatively small (<1‰). We found different binding mechanisms predominate in each land use type. The isotopic signatures of OM fractions from arable soils were highly related to the clay and silt size particles amount while

  12. Vapor Pressure Isotope Effects and the Stable Isotope Geochemistry of the Martian Surface

    NASA Astrophysics Data System (ADS)

    Eiler, J. M.

    2002-12-01

    naturally must be understood before one could confidently identify carbon or oxygen isotope evidence for life. Recent experiments indicate that both ice/vapor and adsorbate/vapor phase changes produce oxygen isotope fractionations of the same direction and magnitude as those for condensation/evaporation of water vapor in the earth's atmosphere. This suggests that seasonal and longer-term cycles of condensation and release of CO2 produce variations of-order 10 % in d18O. The current seasonal cycle of ice-cap formation and sublimation likely produces a similar-magnitude latitudinal gradient in the d18O of CO2. This gradient must be sensitive to mixing between high- and low-latitude air and therefore provides a constraint on martian atmospheric circulation. In contrast, carbon isotopes of CO2 are not measurably fractionated by condensation/sublimation of ice and should be invariant in a martian atmosphere in which this is the only major phase change. Adsorption significantly (ca. 1 to 2 %) concentrates 13CO2 into the vapor phase and 12CO2 into adsorbate. This is opposite in direction to all familiar vapor-pressure isotope effects. Thus, cycles of adsorption/desorption of CO2 have a unique isotopic signature that should be distinguishable for other processes influencing the Martian atmosphere. Measurements of the variation in d13C of CO2 would constrain the extent to which the atmosphere and surface interact by adsorption/desorption processes.

  13. Paleobiological Implications of the Isotopic Signatures ( 13C, 15N) of Fossil Mammal Collagen in Scladina Cave (Sclayn, Belgium)

    NASA Astrophysics Data System (ADS)

    Bocherens, Hervé; Billiou, Daniel; Patou-Mathis, Marylène; Bonjean, Dominique; Otte, Marcel; Mariotti, André

    1997-11-01

    An isotopic investigation of upper Pleistocene mammal bones and teeth from Scladina cave (Sclayn, Belgium) demonstrated the very good quality of collagen preservation. A preliminary screening of the samples used the amount of nitrogen in whole bone and dentine in order to estimate the preserved amount of collagen before starting the extraction process. The isotopic abundances of fossil specimens from still-extant species are consistent with their trophic position. Moreover, the 15N isotopic abundance is higher in dentine than in bone in bears and hyenas, a phenomenon already observed in modern specimens. These results demonstrate that the isotopic compositions of samples from Scladina cave can be interpreted in ecological terms. Mammoths exhibit a high 15N isotopic abundance relative to other herbivores, as was the case in Siberian and Alaskan samples. These results suggest distinctive dietary adaptations in herbivores living in the mammoth steppe. Cave bears are clearly isotopically different from coeval brown bears, suggesting an ecological separation between species, with a pure vegetarian diet for cave bear and an omnivorous diet for brown bear.

  14. Stable isotope, site-specific mass tagging for protein identification

    DOEpatents

    Chen, Xian

    2006-10-24

    Proteolytic peptide mass mapping as measured by mass spectrometry provides an important method for the identification of proteins, which are usually identified by matching the measured and calculated m/z values of the proteolytic peptides. A unique identification is, however, heavily dependent upon the mass accuracy and sequence coverage of the fragment ions generated by peptide ionization. The present invention describes a method for increasing the specificity, accuracy and efficiency of the assignments of particular proteolytic peptides and consequent protein identification, by the incorporation of selected amino acid residue(s) enriched with stable isotope(s) into the protein sequence without the need for ultrahigh instrumental accuracy. Selected amino acid(s) are labeled with .sup.13C/.sup.15N/.sup.2H and incorporated into proteins in a sequence-specific manner during cell culturing. Each of these labeled amino acids carries a defined mass change encoded in its monoisotopic distribution pattern. Through their characteristic patterns, the peptides with mass tag(s) can then be readily distinguished from other peptides in mass spectra. The present method of identifying unique proteins can also be extended to protein complexes and will significantly increase data search specificity, efficiency and accuracy for protein identifications.

  15. Temporal variations in the stable carbon isotopic composition of methane emitted from Minnesota peatlands

    NASA Astrophysics Data System (ADS)

    Kelly, Cheryl A.; Dise, Nancy B.; Martens, Christopher S.

    1992-09-01

    The stable carbon isotopic composition of methane (δ13C) emitted from two peatland sites in the Marcell Experimental Forest in northern Minnesota was investigated during the snow-free season of 1989-1990. A seasonal range in δ13C values of 13‰ was seen for a forested bog with heavier (13C enriched) methane emitted during the wanner summer months. This shift was correlated with water table level suggesting control by microbial oxidation. Methane from a nearby poor fen transitional to bog dominated by Carex oligosperma showed a similar temporal trend but with a much smaller range of 5‰ during the same time period and with no water table level correlation. The methane emitted from the fen was consistently heavier than that emitted by the bog.

  16. Stable isotope analysis of 1987-1991 zooplankton samples and bowhead whale tissues. Final report

    SciTech Connect

    Schell, D.M.

    1992-06-01

    Stable isotope analyses of bowhead whale tissue samples and bowhead whale prey organisms collected over the years 1987 to 1991 were used to provide detail on the isotope ratio gradients evident in the arctic Alaskan zooplankton and to verify previous findings regarding the growth rates and age determination techniques developed for bowhead whales. Zooplankton of the Bering and Chukchi seas are enriched in (13)C relative to the eastern Beaufort Sea. The analysis of baleen from bowhead whales taken between 1987 to 1990 indicate that the whales are slow-growing and the young animals between year one and about six to seven years of age, undergo a period of little or no linear growth. The authors estimate that bowheads require 16-18 years to reach the length of sexual maturity, i.e., 13-14 m. From baleen Delta(13C) cycles, a 20 year record of the isotope ratios in the phytoplankton of the northern Bering and Chukchi seas was constructed. The long-term record has been compared with the temperature anomalies in surface waters of the Bering Sea. The Delta(13C) of the zooplankton is inversely correlated with temperature and refutes current models attempting to relate ocean temperature, and atmospheric carbon dioxide levels with the Delta(13C) of ocean sediment organic matter.

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

    PubMed

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

    2013-01-01

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

  18. Tracing Carbon Sources through Aquatic and Terrestrial Food Webs Using Amino Acid Stable Isotope Fingerprinting

    PubMed Central

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

    2013-01-01

    Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ13C patterns among amino acids (δ13CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ13CAA patterns in contrast to bulk δ13C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ13CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ13C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ13C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs. PMID:24069196

  19. Application of Stable Isotope-Assisted Metabolomics for Cell Metabolism Studies

    PubMed Central

    You, Le; Zhang, Baichen; Tang, Yinjie J.

    2014-01-01

    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. PMID:24957020

  20. Stable isotope analyses reveal the importance of seagrass beds as feeding areas for juvenile Myrophic punctatus in Florida

    EPA Science Inventory

    The feeding habits and habitats of the speckled worm eel Myrophis punctatus were studied on the mangrove edge of the Indian River Lagoon (Florida) using stomach contents and stable isotope analyses of carbon (δ13C) and nitrogen (δ15N). Stomach dietary analyses identified four tax...

  1. STABLE CARBON ISOTOPE EVIDENCE FOR COUPLING BETWEEN SEDIMENTARY BACTERIA AND SEAGRASSES IN A SUB-TROPICAL LAGOON

    EPA Science Inventory

    We measured stable carbon isotope ratios (d13C) in phospholipid fatty acids (PLFAs) to identify the primary carbon source utilized by sedimentary bacteria in Lower Laguna Madre, Texas, which is a seagrass dominated lagoon. Comparisons were made between three differing habitat ty...

  2. PATTERNS OF NITROGEN AND CARBON STABLE ISOTOPE RATIOS IN MACROFUNGI, PLANTS AND SOILS IN TWO OLD-GROWTH CONIFER FORESTS

    EPA Science Inventory

    Natural abundance stable isotope ratios represent a potentially valuable tool for studying fungal ecology. We measured 15N and 13C in ectomycorrhizal and saprotrophic macrofungi from two old-growth conifer forests, and in plants, woody debris, and soils. Fungi, plants, and so...

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

    EPA Science Inventory

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

  4. USE OF THE COMPOSITION AND STABLE CARBON ISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (Gamma 13C) of individual microbial phospholipid fatty acids (PLFAS) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SO...

  5. Variation in the Stable Carbon and Nitrogen Isotope Composition of Plants and Soil along a Precipitation Gradient in Northern China

    PubMed Central

    Ma, Jian-Ying; Sun, Wei; Liu, Xiao-Ning; Chen, Fa-Hu

    2012-01-01

    Water availability is the most influential factor affecting plant carbon (δ13C) and nitrogen (δ15N) isotope composition in arid and semi-arid environments. However, there are potential differences among locations and/or species in the sensitivity of plant δ13C and δ15N to variation in precipitation, which are important for using stable isotope signatures to extract paleo-vegetation and paleo-climate information. We measured δ13C and δ15N of plant and soil organic matter (SOM) samples collected from 64 locations across a precipitation gradient with an isotherm in northern China. δ13C and δ15N for both C3 and C4 plants decreased significantly with increasing mean annual precipitation (MAP). The sensitivity of δ13C to MAP in C3 plants (-0.6±0.07‰/100 mm) was twice as high as that in C4 plants (−0.3±0.08‰/100 mm). Species differences in the sensitivity of plant δ13C and δ15N to MAP were not observed among three main dominant plants. SOM became depleted in 13C with increasing MAP, while no significant correlations existed between δ15N of SOM and MAP. We conclude that water availability is the primary environmental factor controlling the variability of plant δ13C and δ15N and soil δ13C in the studied arid and semi-arid regions. Carbon isotope composition is useful for tracing environmental precipitation changes. Plant nitrogen isotope composition can reflect relative openness of ecosystem nitrogen cycling. PMID:23272186

  6. The carbon abundance and 12C/13C isotopic ratio in the atmosphere of Arcturus from 2.3 µm CO bands

    NASA Astrophysics Data System (ADS)

    Pavlenko, Ya. V.

    2008-09-01

    We have modeled absorption lines of the 12CO and 13CO (Δ υ = 2) molecular bands at λλ 2.29 2.45 µm in the spectrum of Arcturus (K2III). A grid of model atmospheres and synthetic spectra were computed for the red giant using T eff = 4300, log g = 1.5, and the elemental abundances of Peterson et al. (1993), with the exception of the abundances of carbon, log N(C), and oxygen, log N(O) and the carbon isotopic ratio, 12C/13C, which were varied in our computations. The computed spectra were compared to the observed spectrum of Arcturus from the atlas of Hinkle et al. (1976). The best fit between the synthetic and observed spectra is achieved for log N(C) = -3.78, 12C/13C = 8 ± 0.5. We discuss the dependence of 12C/13C on log N(C) and log N(O) in the atmosphere of the red giant.

  7. Compound-Specific Stable Carbon Isotope Analysis of Chlorofluorocarbons in Groundwater.

    PubMed

    Horst, Axel; Lacrampe-Couloume, Georges; Sherwood Lollar, Barbara

    2015-10-20

    Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), controlled substances due to their role in stratospheric ozone loss, also occur as dissolved contaminants in groundwaters. Stable carbon isotopic signatures may provide valuable new information on the fate of these compounds as has been seen for other priority hydrocarbon contaminants, but to date no method for extraction and isotopic analysis of dissolved CFCs from groundwaters has been developed. Here we describe a cryogenic purge and trap system coupled to continuous flow compound-specific stable carbon isotope analysis mass spectrometry for concentrations as low as 35 μg/L. The method is validated by comparing isotopic signatures from water extracted CFCs against a new suite of isotopic CFC standards. Fractionation of CFCs in volatilization experiments from pure-phase CFC-11 and CFC-113 resulted in enrichment factors (ε) of +1.7 ± 0.1‰ and +1.1 ± 0.1‰, respectively, indicating that such volatile loss, if significant, would produce a more (13)C depleted signature in the remaining CFCs. Importantly, no significant fractionation was observed during volatile extraction of dissolved CFCs from aqueous solutions. δ(13)C values for groundwaters from a CFC-contaminated site were, on average, more enriched than δ(13)C values for pure compounds. Such enriched δ(13)C values have been seen in other hydrocarbon contaminants such as chlorinated ethenes and ethanes due to in situ degradation, but definitive interpretation of such enriched signatures in field samples requires additional experiments to characterize fractionation of CFCs during biodegradation. The establishment of a robust and sensitive method of extraction and analysis, as described here, provides the foundation for such future directions. PMID:26383531

  8. Short-term natural δ13C variations in pools and fluxes in a beech forest: the transfer of isotopic signal from recent photosynthates to soil respired CO2

    NASA Astrophysics Data System (ADS)

    Gavrichkova, O.; Proietti, S.; Moscatello, S.; Portarena, S.; Battistelli, A.; Matteucci, G.; Brugnoli, E.

    2011-03-01

    The fate of photosynthetic products within the plant-soil continuum determines how long the reduced carbon resides within the ecosystem and when it returns back to the atmosphere in the form of respiratory CO2. We have tested the possibility of measuring natural variation in δ13C to disentangle potential times needed to transfer carbohydrates produced by photosynthesis down to roots and, in general, to belowground up to its further release in the form of soil respiration into the atmosphere in a beech (Fagus sylvatica) forest. For these purposes we have measured the variation in stable carbon and oxygen isotope compositions in plant material and in soil respired CO2 every three hours for three consequent days. Possible steps and different signs of post-photosynthetic fractionation during carbon translocation were also identified. A 12 h-periodicity was observed for variation in δ13C in soluble sugars in the top crown leaves and it can be explained by starch day/night dynamics in synthesis and breakdown and by stomatal limitations under elevated vapour pressure deficits. Photosynthetic products were transported down the trunk and mixed with older carbon pools, therefore causing the dampening of the δ13C signal variation. The strongest periodicity of 24 h was found in δ13C in soil respiration indicating changes in root contribution to the total CO2 efflux. Nevertheless, it was possible to identify the speed of carbon translocation through the plant-soil continuum. A period of 24 h was needed to transfer the C assimilated by photosynthesis from the top crown leaves to the tree trunk at breast height and additional 3 h for further respiration of that C by roots and soil microorganisms and its to subsequent diffusion back to the atmosphere.

  9. sup 18 O/ sup 16 O and sup 13 C/ sup 12 C in lower Paleozoic articulate brachiopods: Implications for the isotopic composition of seawater

    SciTech Connect

    Wadleigh, M.A. ); Veizer, J. Ruhr Univ., Bochum )

    1992-01-01

    Three hundred and eleven articulate brachiopods, with extensive geographic coverage, spanning the Cambrian to Silurian stratigraphic interval, were analyzed for oxygen and carbon isotopic composition. Cambrian samples have {delta}{sup 18}O {le} {minus}7{per thousand}, Ordovician samples {le} {minus}2.4{per thousand}, and Silurian samples {le} {minus}1.9{per thousand}, confirming the previously established trend towards lighter isotopic compositions with increasing age throughout the Lower Paleozoic. Forty-nine best preserved' Ordovician and Silurian samples were identified based on scanning electron microscopy and trace element analysis. They were found to bracket the isotopic compositions of over 85% of specimens from these stratigraphic intervals supporting widespread preservation of the isotopic signal. Some latest Ordovician and Lower Ludlovian samples associated with shale sequences are apparently enriched' in {sup 18}O. These are interpreted as an environmental phenomenon, perhaps related to water temperature and glaciation. A number of Silurian samples of varying genera and stratigraphic levels are highly enriched in {sup 13}C, up to +6{per thousand}. Some are shale related, but some are associated with carbonate-bearing basins. These are also thought to represent near-original' compositions, but a single environmental cause is unknown. The present data show that luminescence is not a decisive criterion for evaluating the degree of brachiopod preservation. Whole-shell values were isotopically similar to their nonluminescent portions for both oxygen and carbon.

  10. Stable Vanadium Isotope Fractionation at High Temperatures

    NASA Astrophysics Data System (ADS)

    Prytulak, J.; Parkinson, I. J.; Savage, P. S.; Nielsen, S. G.; Halliday, A. N.

    2011-12-01

    Vanadium is a redox sensitive transition metal existing in multiple valence states at terrestrial conditions. Stable vanadium isotopes (reported as δ51V in % relative to an Alfa Aesar standard [1]) are a potentially powerful tracer of oxidation-reduction processes. However, the determination of δ51V is analytically challenging, primarily due to the extreme abundance ratio between the only two stable isotopes (51V/50V ~ 400) and, also, significant isobaric interferences of 50Ti and 50Cr on the minor 50V isotope. We have developed the first method able to determine δ51V to a precision (2 s.d. ~ 0.15%, [1,2]) that enables application of this isotope system to geological processes. To usefully investigate high temperature processes using vanadium isotopes, knowledge of the isotope composition and range of values present in the ambient mantle is required. Here we discuss the first δ51V measured in igneous materials encompassing peridotites, MORB, and primitive mantle-derived melts such as picrites. This first dataset provides a preliminary reconnaissance of the magnitude of natural fractionation. We find little isotope fractionation in suites of peridotites and MORB (< 0.5 %). However, the small but analytically significant variation appears to be related to secondary processes, with extremely altered peridotites consistently displaying slightly heavier isotope compositions. We find no resolvable δ51V variation between fresh MORB glass and fresh peridotite. Intriguingly, a suite of subduction-related peridotites from the Mariana forearc, previously characterized for fO2 [3], do not display the predicted co-variation between δ51V and fO2, but instead also have compositions identical to MORB glass. This nominally supports recent indications that there is limited difference in the oxygen fugacity of the MORB source and the subarc mantle wedge [e.g., 4, 5]. Finally, we observe large δ51V variations (~ 2 %) in a suite of evolving lavas from Hekla volcano, Iceland

  11. The C-13/C-12 kinetic isotope effect for soil oxidation of methane at ambient atmospheric concentrations

    NASA Technical Reports Server (NTRS)

    King, Stagg L.; Quay, Paul D.; Lansdown, John M.

    1989-01-01

    During a survey of the Alaskan North Slope to estimate the isotopic composition and fluxes of methane (CH4) from the tundra, two sites were encountered that showed net methane consumption within flux chambers. Methane concentrations decreased from ambient (1.78 ppmv) by up to 50 percent, and the delta C-13 increased by up to 10 percent in the two chamber deployments showing CH4 consumption. CH4 consumption rates were measured to be 1.2 and 0.6 mg CH4/sq m per day; the corresponding carbon kinetic isotope effects (k13/k12) were 0.974 and 0.984, respectively.

  12. Reductive carbonylation of aryl halides employing a two-chamber reactor: a protocol for the synthesis of aryl aldehydes including 13C- and D-isotope labeling.

    PubMed

    Korsager, Signe; Taaning, Rolf H; Lindhardt, Anders T; Skrydstrup, Troels

    2013-06-21

    A protocol has been developed for conducting the palladium-catalyzed reductive carbonylation of aryl iodides and bromides using 9-methylfluorene-9-carbonyl chloride (COgen) as a source of externally delivered carbon monoxide in a sealed two-chamber system (COware), and potassium formate as the in situ hydride source. The method is tolerant to a wide number of functional groups positioned on the aromatic ring, and it can be exploited for the isotope labeling of the aldehyde group. Hence, reductive carbonylations run with (13)COgen provide a facile access to (13)C-labeled aromatic aldehydes, whereas with DCO2K, the aldehyde is specifically labeled with deuterium. Two examples of double isotopic labeling are also demonstrated. Finally, the method was applied to the specific carbon-13 labeling of the β-amyloid binding compound, florbetaben. PMID:23692554

  13. Implications of the large carbon kinetic isotope effect in the reaction CH4 + Cl for the 13C/12C ratio of stratospheric CH4

    NASA Astrophysics Data System (ADS)

    Bergamaschi, P.; Brühl, C.; Brenninkmeijer, C. A. M.; Saueressig, G.; Crowley, J. N.; Grooß, J. U.; Fischer, H.; Crutzen, P. J.

    Recent investigations of the carbon kinetic isotope effect (KIE) of the reaction CH4 + Cl yielded KIECl = 1.066±0.002 at 297 K (increasing to 1.075±0.005 at 223 K) [Saueressig et al., 1995]. In order to assess the effect of the exceptionally large KIEcl on δ13C of stratospheric CH4 we applied a two-dimensional, time dependent chemical transport model. The model results demonstrate the strong influence of the CH4 + Cl reaction on δ13CH4 in particular in the middle and upper stratosphere, where this reaction contributes several tens of percent to the total CH4 sink. The Cl sink helps to explain the relatively large overall isotope fractionation of 1.010-1.012 observed in the lower stratosphere [Brenninkmeijer et al., 1995; Brenninkmeijer et al., 1996], even though the model results predict a smaller effect than observed.

  14. Stable Carbon Isotope Fractionation in Chlorinated Ethene Degradation by Bacteria Expressing Three Toluene Oxygenases

    PubMed Central

    Clingenpeel, Scott R.; Moan, Jaina L.; McGrath, Danielle M.; Hungate, Bruce A.; Watwood, Mary E.

    2012-01-01

    One difficulty in using bioremediation at a contaminated site is demonstrating that biodegradation is actually occurring in situ. The stable isotope composition of contaminants may help with this, since they can serve as an indicator of biological activity. To use this approach it is necessary to establish how a particular biodegradation pathway affects the isotopic composition of a contaminant. This study examined bacterial strains expressing three aerobic enzymes for their effect on the 13C/12C ratio when degrading both trichloroethene (TCE) and cis-1,2-dichloroethene (c-DCE): toluene 3-monoxygenase, toluene 4-monooxygenase, and toluene 2,3-dioxygenase. We found no significant differences in fractionation among the three enzymes for either compound. Aerobic degradation of c-DCE occurred with low fractionation producing δ13C enrichment factors of −0.9 ± 0.5 to −1.2 ± 0.5, in contrast to reported anaerobic degradation δ13C enrichment factors of −14.1 to −20.4‰. Aerobic degradation of TCE resulted in δ13C enrichment factors of −11.6 ± 4.1 to −14.7 ± 3.0‰ which overlap reported δ13C enrichment factors for anaerobic TCE degradation of −2.5 to −13.8‰. The data from this study suggest that stable isotopes could serve as a diagnostic for detecting aerobic biodegradation of TCE by toluene oxygenases at contaminated sites. PMID:22363335

  15. Spatially tracking 13C labeled substrate (bicarbonate) accumulation in microbial communities using laser ablation isotope ratio mass spectrometry

    SciTech Connect

    Moran, James J.; Doll, Charles G.; Bernstein, Hans C.; Renslow, Ryan S.; Cory, Alexandra B.; Hutchison, Janine R.; Lindemann, Stephen R.; Fredrickson, Jim K.

    2014-08-25

    This is a manuscript we would like to submit for publication in Environmental Microbiology Reports. This manuscript contains a description of a laser ablation isotope ratio mass spectrometry methodology developed at PNNL and applied to a microbial system at a PNNL project location – Hot Lake, Washington. I will submit a word document containing the entire manuscript with this Erica input request form.

  16. [Application of stable carbon isotope technique in the research of carbon cycling in soil-plant system].

    PubMed

    Liu, Wei; Lü, Hao-Hao; Chen, Ying-Xu; Wu, Wei-Xiang

    2008-03-01

    As a main life element, carbon plays important role in the matter cycling in soil-plant system. Stable carbon isotope 13C has been widely used in the study of carbon cycling in soil-plant system, due to its safe, no pollution, and easy to be handled. Through the analysis of both natural and labeled 13C organic matter in soil-plant system, a better understanding of the mechanisms of photosynthesis, the distribution of photosynthates in plant-soil system, the fate of plant litter, and the source of new carbon in soil could be achieved. In this paper, the applications of stable carbon isotope technique in the researches of photosynthesis, reconstruction of paleoclimate, turnover of soil organic matter, and interactions between plants and rhizosphere microorganisms were briefly summarized, and the perspectives of the application of stable carbon isotope technique were also discussed, based on the issues existed in current researches. PMID:18533543

  17. Niche differentiation and dietary seasonality among sympatric gorillas and chimpanzees in Loango National Park (Gabon) revealed by stable isotope analysis.

    PubMed

    Oelze, Vicky M; Head, Josephine S; Robbins, Martha M; Richards, Michael; Boesch, Christophe

    2014-01-01

    The feeding ecology of sympatric great ape species yields valuable information for palaeodietary reconstructions in sympatric early hominin species. However, no isotopic references on sympatrically living apes and their feeding ecology are currently available. Here we present the first isotopic study on sympatric great apes, namely western lowland gorillas (Gorilla gorilla gorilla) and central chimpanzees (Pan troglodytes troglodytes) from Loango National Park, Gabon. We successfully analyzed the stable carbon and nitrogen isotope ratios in a selection of food plants (n = 31) and hair samples (n = 30) retrieved from sleeping nests to test whether niche partitioning among sympatric chimpanzees and gorillas is detectable using isotope analysis of hair. Ape hair strands with roots were sectioned into sequential segments (n = 100) to investigate temporal isotopic variation related to seasonal variations in food resources. We found significant δ(13)C differences between herbaceous plants and fruits, most likely due to canopy effects. While the δ(13)C values of chimpanzees indicate the consumption of fruit, the low δ(13)C values in gorilla hair indicate folivory, most likely the consumption of (13)C-depleted herbaceous vegetation. Our isotopic data also confirmed dietary overlap between chimpanzees and gorillas, which varied by season. Gorillas showed significant variation in δ(13)C values in response to season due to shifting proportions of herbaceous plants versus fruits. In chimpanzees, significant seasonal variation in δ(15)N was likely related to the seasonal availability of fruit species with particularly high δ(15)N values. In summary, we found isotopic evidence for niche partitioning and seasonal dietary variation among sympatric great apes at Loango. These findings provide a valuable reference for palaeodietary research on fossil hominins using δ(13)C analyses, particularly for studies focusing on sympatric taxa and on temporal isotopic variation

  18. Stable isotope signatures for characterising the biological stability of landfilled municipal solid waste

    SciTech Connect

    Wimmer, Bernhard; Hrad, Marlies; Huber-Humer, Marion; Watzinger, Andrea; Wyhlidal, Stefan; Reichenauer, Thomas G.

    2013-10-15

    Highlights: ► The isotopic signature of δ{sup 13}C-DIC of leachates is linked to the reactivity of MSW. ► Isotopic signatures of leachates depend on aerobic/anaerobic conditions in landfills. ► In situ aeration of landfills can be monitored by isotope analysis in leachate. ► The isotopic analysis of leachates can be used for assessing the stability of MSW. ► δ{sup 13}C-DIC of leachates helps to define the duration of landfill aftercare. - Abstract: Stable isotopic signatures of landfill leachates are influenced by processes within municipal solid waste (MSW) landfills mainly depending on the aerobic/anaerobic phase of the landfill. We investigated the isotopic signatures of δ{sup 13}C, δ{sup 2}H and δ{sup 18}O of different leachates from lab-scale experiments, lysimeter experiments and a landfill under in situ aeration. In the laboratory, columns filled with MSW of different age and reactivity were percolated under aerobic and anaerobic conditions. In landfill simulation reactors, waste of a 25 year old landfill was kept under aerobic and anaerobic conditions. The lysimeter facility was filled with mechanically shredded fresh waste. After starting of the methane production the waste in the lysimeter containments was aerated in situ. Leachate and gas composition were monitored continuously. In addition the seepage water of an old landfill was collected and analysed periodically before and during an in situ aeration. We found significant differences in the δ{sup 13}C-value of the dissolved inorganic carbon (δ{sup 13}C-DIC) of the leachate between aerobic and anaerobic waste material. During aerobic degradation, the signature of δ{sup 13}C-DIC was mainly dependent on the isotopic composition of the organic matter in the waste, resulting in a δ{sup 13}C-DIC of −20‰ to −25‰. The production of methane under anaerobic conditions caused an increase in δ{sup 13}C-DIC up to values of +10‰ and higher depending on the actual reactivity of the MSW

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

    PubMed

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

    2016-01-01

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

  20. Stable isotopic compositions in Australian precipitation

    NASA Astrophysics Data System (ADS)

    Liu, Jianrong; Fu, Guobin; Song, Xianfang; Charles, Stephen P.; Zhang, Yinghua; Han, Dongmei; Wang, Shiqin

    2010-12-01

    Stable deuterium (δD) and oxygen-18 (δ18O) isotopes in 1962 to 2002 precipitation from the seven Australian stations of the Global Network of Isotopes in Precipitation (GNIP) were used to investigate isotope characteristics including temporal and spatial distributions across different regions of Australia. On the basis of 1534 samples, the local meteoric water line (LMWL) was established as δD = 7.10δ18O + 8.21. δ18O showed a depletion trend from north and south to central Australia (a continental effect) and from west to east. Precipitation amount effects were generally greater than temperature effects, with quadratic or logarithmic correlations describing δ/T and δ/P better than linear relationships. Nonlinear stepwise regression was used to determine the significant meteorological control factors for each station, explaining about 50% or more of the δ18O variations. Geographical control factors for δ18O were given by the relationship δ18O (‰) = -0.005 longitude (°) - 0.034 latitude (°)-0.003 altitude (m) - 4.753. Four different types of d-excess patterns demonstrated particular precipitation formation conditions for four major seasonal rainfall zones. Finally, wavelet coherence (WTC) between δ18O and SOI confirmed that the influence of ENSO decreased from east and north to west Australia.

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

    SciTech Connect

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

    1988-11-01

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

  2. Identification of Methane, Ethane, and Propane Oxidizing Bacteria at Marine Hydrocarbon Seeps by Stable Isotope Probing

    NASA Astrophysics Data System (ADS)

    Redmond, M.; Ding, H.; Friedrich, M. W.; Valentine, D. L.

    2008-12-01

    Hydrocarbon seeps emit substantial amounts of oil and natural gas into the marine environment, where they can be oxidized by microorganisms in the sediment and water column. Here, we used stable isotope probing of DNA and lipid biomarkers to identify the microorganisms actively consuming 13C-labeled natural gas compounds in seep sediment samples. Surface sediment was collected from the Coal Oil Point seep field (offshore Santa Barbara, California, USA) and incubated under aerobic conditions with 13C labeled methane, ethane, or propane for up to 37 days, with sediment sub-samples taken at 3-4 intermediate time points. DNA was extracted from sediment and separated by CsCl density gradient centrifugation. The microbial community in each fraction was profiled using T-RFLP, and bacterial 16S rRNA gene clone libraries were constructed from un-incubated hydrocarbon seep sediment and selected isotopically 'heavy' (13C) and 'light' (12C) gradient fractions from ethane incubations. All clone libraries were dominated by sequences from members of the family Rhodobacteraceae (>25% of sequences) and a diverse group of Gammaproteobacteria, including sequences related to those of methylotrophs and to those of bacteria known to consume the longer-chain alkanes present in crude oil. After 14 days of incubation, the relative abundance of Rhodobacteraceae was higher in 'heavy' fractions from the 13C-ethane incubation than in 'light' fractions, suggesting incorporation of 13C label. The Rhodobacteraceae are very diverse metabolically, but have often been observed in abundance in oil contaminated seawater. Several members of this group have been shown to oxidize longer chain alkanes (C10 or higher), but none have been previously linked to the consumption of the gaseous alkanes ethane, propane, and butane. For the final time point, 13C content of phospholipid fatty acids (PLFA) were also analyzed, showing substantial incorporation of 13C over 37 days. In the methane incubation

  3. Existing and emerging technologies for measuring stable isotope labelled retinol in biological samples: isotope dilution analysis of body retinol stores.

    PubMed

    Preston, Tom

    2014-01-01

    This paper discusses some of the recent improvements in instrumentation used for stable isotope tracer measurements in the context of measuring retinol stores, in vivo. Tracer costs, together with concerns that larger tracer doses may perturb the parameter under study, demand that ever more sensitive mass spectrometric techniques are developed. GCMS is the most widely used technique. It has high sensitivity in terms of sample amount and uses high resolution GC, yet its ability to detect low isotope ratios is limited by background noise. LCMSMS may become more accessible for tracer studies. Its ability to measure low level stable isotope tracers may prove superior to GCMS, but it is isotope ratio MS (IRMS) that has been designed specifically for low level stable isotope analysis through accurate analysis of tracer:tracee ratios (the tracee being the unlabelled species). Compound-specific isotope analysis, where GC is interfaced to IRMS, is gaining popularity. Here, individual 13C-labelled compounds are separated by GC, combusted to CO2 and transferred on-line for ratiometric analysis by IRMS at the ppm level. However, commercially-available 13C-labelled retinol tracers are 2 - 4 times more expensive than deuterated tracers. For 2H-labelled compounds, GC-pyrolysis-IRMS has now become more generally available as an operating mode on the same IRMS instrument. Here, individual compounds are separated by GC and pyrolysed to H2 at high temperature for analysis by IRMS. It is predicted that GC-pyrolysis-IRMS will facilitate low level tracer procedures to measure body retinol stores, as has been accomplished in the case of fatty acids and amino acids. Sample size requirements for GC-P-IRMS may exceed those of GCMS, but this paper discusses sample preparation procedures and predicts improvements, particularly in the efficiency of sample introduction. PMID:25537104

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  5. Trophic Discrimination Factors of Stable Carbon and Nitrogen Isotopes in Hair of Corn Fed Wild Boar

    PubMed Central

    Holá, Michaela; Ježek, Miloš; Kušta, Tomáš; Košatová, Michaela

    2015-01-01

    Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species- specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were –2.3 ‰ and +3.5 ‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d-1. Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types. PMID:25915400

  6. Trophic discrimination factors of stable carbon and nitrogen isotopes in hair of corn fed wild boar.

    PubMed

    Holá, Michaela; Ježek, Miloš; Kušta, Tomáš; Košatová, Michaela

    2015-01-01

    Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species-specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were -2.3‰ and +3.5‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d(-1). Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types. PMID:25915400

  7. Stable carbon isotopic composition of low-molecular-weight dicarboxylic acids and ketoacids in remote marine aerosols

    NASA Astrophysics Data System (ADS)

    Wang, Haobo; Kawamura, Kimitaka

    2006-04-01

    We determined stable carbon isotopic composition (δ13C) of C2 to C9 dicarboxylic acids (DCAs) and some ketoacids in the marine aerosols from the western Pacific and Southern Ocean (35°N to 65°S). On average, oxalic (mean, -16.8‰), adipic (-17.2‰), and glyoxylic (-17.6‰) acids showed heavier δ13C, whereas maleic (-24.2‰), methylmalonic (-23.6‰), and phthalic (-23.1‰) acids were more depleted in 13C. Oxalic acid presented very diverse δ13C values (-27 to -7‰), which increased from midlatitudes toward the equator. A similar latitudinal trend of δ13C was also found for malonic, succinic, and adipic acids. However, such a trend was not observed for phthalic, maleic, and glyoxylic acids. We suggest that the δ13C increase toward the equator is associated with photochemically aged air masses, in which kinetic isotope effects for photochemical degradation of DCAs may be important. Differences in δ13C of some saturated DCAs were also found to increase from midlatitudes to the equator.

  8. Source Apportionment of Polycyclic Aromatic Hydrocarbons in Central European Soils with Compound-Specific Triple Isotopes (δ(13)C, Δ(14)C, and δ(2)H).

    PubMed

    Bosch, Carme; Andersson, August; Kruså, Martin; Bandh, Cecilia; Hovorková, Ivana; Klánová, Jana; Knowles, Timothy D J; Pancost, Richard D; Evershed, Richard P; Gustafsson, Örjan

    2015-07-01

    This paper reports the first study applying a triple-isotope approach for source apportionment of polycyclic aromatic hydrocarbons (PAHs). The (13)C/(12)C, (14)C/(12)C, and (2)H/(1)H isotope ratios of PAHs were determined in forest soils from mountainous areas of the Czech Republic, European Union. Statistical modeling applying a Bayesian Markov chain Monte Carlo (MCMC) framework to the environmental triple isotope PAH data and an end-member PAH isotope database allowed comprehensive accounting of uncertainties and quantitative constraints on the PAH sources among biomass combustion, liquid fossil fuel combustion, and coal combustion at low and high temperatures. The results suggest that PAHs in this central European region had a clear predominance of coal combustion sources (75 ± 6%; uncertainties represent 1 SD), mainly coal pyrolysis at low temperature (∼650 °C; 61 ± 8%). Combustion of liquid fossil fuels and biomass represented 16 ± 3 and 9 ± 3% of the total PAH burden (∑PAH14), respectively. Although some soils were located close to potential PAH point sources, the source distribution was within a narrow range throughout the region. These observation-based top-down constraints on sources of environmental PAHs provide a reference for both improved bottom-up emission inventories and guidance for efforts to mitigate PAH emissions. PMID:26053501

  9. Chemical weathering and the role of sulfuric and nitric acids in carbonate weathering: Isotopes (13C, 15N, 34S, and 18O) and chemical constraints

    NASA Astrophysics Data System (ADS)

    Li, Cai; Ji, Hongbing

    2016-05-01

    Multiple isotopes (13C-DIC, 34S and 18O-SO42-, 15N and 18O-NO3-) and water chemistry were used to evaluate weathering rates and associated CO2 consumption by carbonic acid and strong acids (H2SO4 and HNO3) in a typical karst watershed (Wujiang River, Southwest China). The dual sulfate isotopes indicate that sulfate is mainly derived from sulfide oxidation in coal stratum and sulfide-containing minerals, and dual nitrate isotopes indicate that nitrate is mainly derived from soil N and nitrification. The correlation between isotopic compositions and water chemistry suggests that sulfuric and nitric acids, in addition to carbonic acid, are involved in carbonate weathering. The silicate and carbonate weathering rates are 7.2 t km-2 yr-1 and 76 t km-2 yr-1, respectively. In comparison with carbonate weathering rates (43 t km-2 yr-1) by carbonic acid alone, the subsequent increase in rates indicates significant enhancement of weathering when combined with sulfuric and nitric acids. Therefore, the role of sulfuric and nitric acids in the rock weathering should be considered in the global carbon cycle.

  10. A survey of methane isotope abundance (14C, 13C, 2H) from five nearshore marine basins that reveals unusual radiocarbon levels in subsurface waters

    NASA Astrophysics Data System (ADS)

    Kessler, J. D.; Reeburgh, W. S.; Valentine, D. L.; Kinnaman, F. S.; Peltzer, E. T.; Brewer, P. G.; Southon, J.; Tyler, S. C.

    2008-12-01

    Methane (CH4) in the subsurface ocean is often supersaturated compared to equilibrium with the modern atmosphere. In order to investigate sources of CH4 to the subsurface ocean, isotope surveys (14C-CH4,δ13C-CH4, δ2H-CH4) were conducted at five locations: Skan Bay (SB), Santa Barbara Basin (SBB), Santa Monica Basin (SMB), Cariaco Basin (CB), and the Guaymas Basin (GB). Depth distributions of CH4 concentration and isotopic abundance were determined for both the sediment and water column at the SB, SBB, SMB, and CB sites; CH4 emitted from seeps on the continental shelf adjacent to the SBB as well as seeps and decomposing clathrate hydrates in the GB was also collected, purified, and analyzed. Methane isotope distributions in the sediments were consistent with known methanogenic and methanotrophic activity; seep- and clathrate-hydrate-derived CH4 was found to be depleted in radiocarbon. However, surprising results were obtained in the water column at all sites investigated. In SB the radiocarbon content of the subsurface CH4 concentration maximum was on average 41% less than its suspected sediment CH4 source, suggesting CH4 seepage in the bay. In the SBB, SMB, and CB, the 14C-CH4 contents in the subsurface ocean were 1.2 to 3.6 times greater than modern carbon quantities suggesting a source of 14C from atmospheric nuclear weapons testing, nuclear power plant effluents, or cosmogenic isotope production.

  11. Stable Carbon Isotope Discrimination Is under Genetic Control in the C4 Species Maize with Several Genomic Regions Influencing Trait Expression1[W

    PubMed Central

    Gresset, Sebastian; Westermeier, Peter; Rademacher, Svenja; Ouzunova, Milena; Presterl, Thomas; Westhoff, Peter; Schön, Chris-Carolin

    2014-01-01

    In plants with C4 photosynthesis, physiological mechanisms underlying variation in stable carbon isotope discrimination (Δ13C) are largely unknown, and genetic components influencing Δ13C have not been described. We analyzed a maize (Zea mays) introgression library derived from two elite parents to investigate whether Δ13C is under genetic control in this C4 species. High-density genotyping with the Illumina MaizeSNP50 Bead Chip was used for a detailed structural characterization of 89 introgression lines. Phenotypic analyses were conducted in the field and in the greenhouse for kernel Δ13C as well as plant developmental and photosynthesis-related traits. Highly heritable significant genetic variation for Δ13C was detected under field and greenhouse conditions. For several introgression library lines, Δ13C values consistently differed from the recurrent parent within and across the two phenotyping platforms. Δ13C was significantly associated with 22 out of 164 analyzed genomic regions, indicating a complex genetic architecture of Δ13C. The five genomic regions with the largest effects were located on chromosomes 1, 2, 6, 7, and 9 and explained 55% of the phenotypic variation for Δ13C. Plant development stage had no effect on Δ13C expression, as phenotypic as well as genotypic correlations between Δ13C, flowering time, and plant height were not significant. To our knowledge, this is the first study demonstrating Δ13C to be under polygenic control in the C4 species maize. PMID:24280436

  12. Geographical origin of cereal grains based on element analyser-stable isotope ratio mass spectrometry (EA-SIRMS).

    PubMed

    Wu, Yuluan; Luo, Donghui; Dong, Hao; Wan, Juan; Luo, Haiying; Xian, Yanping; Guo, Xindong; Qin, Fangfang; Han, Wanqing; Wang, Li; Wang, Bin

    2015-05-01

    The stable carbon and nitrogen isotopic compositions (δ(13)C and δ(13)N) of different cereal grains from different regions were determined, using element analyser-stable isotope ratio mass spectrometry (EA-SIRMS) as the key method. Systematically, δ(13)C and δ(13)N of 5 kinds of cereal grains of different origins, 30 wheat samples from different cultivation areas and 160 rice samples of different cultivars from Guangdong province of China were examined. The results indicated that the δ(13)C values of rice, soybean, millet, wheat and corn were significantly (P < 0.05) different within different origins (Heilongjiang, Shandong and Jiangsu province of China), respectively, while δ(13)N values were not. Interestingly, there exists discrimination between these 5 kinds of cereals grains, no matter C-3 or C-4 plants. Further study showed that the δ(13)C values of wheat from Australia, the USA, Canada, and Jiangsu and Shandong province of China were also significantly (P < 0.01) different. Furthermore, the P-value test for 160 rice samples of 5 cultivars was not significant (P > 0.05), which indicated that the cultivar of cereal grains was not significant based on δ(13)C value. Thus, the comparison of δ(13)C would be potentially useful for rapid and routine discrimination of geographical origin of cereal grains. PMID:25529718

  13. Dietary Heterogeneity among Western Industrialized Countries Reflected in the Stable Isotope Ratios of Human Hair

    PubMed Central

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

    2012-01-01

    Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization). Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ13C values (−22.7 to −18.3‰), and significantly higher δ15N (7.8 to 10.3‰) and δ34S (4.8 to 8.3‰) values than samples from the USA (δ13C: −21.9 to −15.0‰, δ15N: 6.7 to 9.9‰, δ34S: −1.2 to 9.9‰). Within Europe, we detected differences in hair δ13C and δ34S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments. PMID:22479574

  14. 13C and 18O fractionation effects on open splits and on the ion source in continuous flow isotope ratio mass spectrometry.

    PubMed

    Elsig, Joachim; Leuenberger, Markus C

    2010-05-30

    Measurements of carbon and oxygen isotopes of CO(2) by continuous flow isotope ratio mass spectrometry are widely used in environmental studies and climate change research. Yet, there are remaining problems associated with the reproducibility of measurements, in particular when high precision is required and/or the amount of sample material is limited. Isotopic fractionations in open splits and nonlinear effects occurring in the mass spectrometer due to different sample amounts alter the results. In this study, we discuss the influence and the origin of these two effects and propose procedures for preventing their impact. Fractionation in the open split can be related to diffusion of CO(2) and can lead to shifted delta-values when measuring a sample gas against a reference gas injected via different open splits. We present a method, where such fractionations can be minimized by adjusting either the position of the capillaries or the flow rates involved or both. The nonlinear peak area dependence of delta(13)C measurements for small sample sizes can be explained by adsorption/desorption processes in the ionization chamber or its vicinity. For constant amplitudes, the magnitude of the nonlinearity only depends on the amount of CO(2) entering the ion source. This nonlinearity can be eliminated by a small additional flux of a conditioning gas fed to the mass spectrometer. The best results were obtained when using carbon monoxide. For the adsorption process in the mass spectrometer we found a fractionation factor of 0.982 +/- 0.005 for delta(13)C and 1.002 +/- 0.004 for delta(18)O. PMID:20411581

  15. The fractionation factors of stable carbon and hydrogen isotope ratios for VOCs

    NASA Astrophysics Data System (ADS)

    Kawashima, H.

    2014-12-01

    Volatile organic compounds (VOCs) are important precursors of ozone and secondary organic aerosols in the atmosphere, some of which are carcinogenic, teratogenic, or mutagenic. VOCs in ambient air originate from many sources, including vehicle exhausts, gasoline evaporation, solvent use, natural gas emissions, and industrial processes, and undergo intricate chemical reactions in the atmosphere. To develop efficient air pollution remediation strategies, it is important to clearly identify the emission sources and elucidate the reaction mechanisms in the atmosphere. Recently, stable carbon isotope ratios (δ13C) of VOCs in some sources and ambient air have been measured by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). In this study, we measured δ13C and stable hydrogen isotope ratios (δD) of atmospheric VOCs by using the gas chromatography/thermal conversion/isotope ratio mass spectrometry coupled with a thermal desorption instrument (TD-GC/TC/IRMS). The wider δD differences between sources were found in comparison with the δ13C studies. Therefore, determining δD values of VOCs in ambient air is potentially useful in identifying VOC sources and their reactive behavior in the atmosphere. However, to elucidate the sources and behavior of atmospheric VOCs more accurately, isotopic fractionation during atmospheric reaction must be considered. In this study, we determined isotopic fractionation of the δ13C and δD values for the atmospheric some VOCs under irradiation conditions. As the results, δ13C for target all VOCs and δD for most VOCs were increasing after irradiation. But, the δD values for both benzene and toluene tended to decrease as irradiation time increased. We also estimated the fractionation factors for benzene and toluene, 1.27 and 1.05, respectively, which differed from values determined in previous studies. In summary, we were able to identify an inverse isotope effect for the δD values of benzene and toluene

  16. Using C stable isotopes to infer shifting metabolism in response to variable environmental conditions

    NASA Astrophysics Data System (ADS)

    Ballantyne, Ford; Billings, Sharon; Lehmeier, Christoph; Min, Kyungjin

    2014-05-01

    for such isotopic effects is critical for a better interpretation of δ13C of soil respiration. Finally, we emphasize that performing controlled experiments, such as in chemostats, is critical for identifying and interrogating mechanisms responsible for the genesis of patterns in stable isotopes.

  17. Effects of acid washing on stable isotope ratios of C and N in penaeid shrimp and seagrass: Implications for food-web studies using multiple stable isotopes

    SciTech Connect

    Bunn, S.E.; Kempster, M.A.; Loneragan, N.R.

    1995-05-01

    We investigated the effects of acid washing on the carbon and nitrogen composition and stable isotope ratios of C and N in shrimp (Metapenaeus spp.) and seagrass (Enhalus acoroides). Acid washing did not affect the mean {delta}{sup 13}C ratios for juvenile Metapenaeus moyebi and resulted in only an ecologically insignificant change (0.3%) in mean {delta}{sup 13}C ratios for larger metapenaeus bennettae. In contrast, acid washing increased the mean {delta}{sup 15}N signatures of shrimp tissue ({approximately}3%) and decreased that of seagrass ({approximately}1.8%) to a degree that may confound the interpretation of food webs. The increase in %C and %N in both shrimp and seagrass after acid washing suggests that the changes in isotope ratios are due to loss of molecules comparatively low in C and N. Treating samples by acid washing also resulted in an increase in the variation among individuals for both {delta}{sup 15}N and {delta}{sup 13}C, which would lead to a loss of statistical power for testing differences between species, sites, or seasons. 13 refs., 2 figs., 1 tab.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Recent breakthroughs in ultra-clean seawater sampling, analytical instrumentation and chemical separation of trace metals have led to significant improvement in both sensitivity and accuracy of concentration measurements of some key bio-limiting metals such as Zn, Cd and Fe. Stable isotope fractionations of these transition metal elements have added a further new dimension to our understanding of the marine biogeochemical cycling of trace nutrients. Improving our understanding of the latter is essential for assessing the impact of climate changes on the global carbon cycle, given the control of oceanic nutrient inventories on the efficiency of the "biological pump" and hence, its strength in regulating the sequestration of atmospheric CO2. The first reliable vertical distribution profiles of trace metal element cadmium (Cd) in the oceans [1, 2] showed a correlation with the major nutrient phosphate. This apparent involvement of Cd in the ocean biological cycle was unexpected, as Cd was known to be toxic, notably at high Cd abundance where it interferes with the true biological function of zinc (Zn), due to their similar chemistry. The novel ability to measure accurately the stable isotope fractionation of Cd in seawater may now help unravel the apparent role of Cd in the ocean biological cycle, akin to the classical breakthroughs and numerous applications of the ratio 13C/12C for understanding the ocean carbon cycle. We have examined the distribution of Cd concentration and isotope ratios in depth profiles from the High Nutrients Low Chlorophyll (HNLC) Southern Ocean, collected within the framework of the international GEOTRACES program. The first surface water transect along the Greenwich Meridian in the Southern Ocean revealed a strong meridional isotope gradient and two major biogeochemical provinces with distinctive Cd isotope fractionation factors, apparently related to phytoplankton community compositions and cellular uptake mechanisms [3]. Here we focus on

  19. Stable Isotope-Assisted Metabolomics for Network-Wide Metabolic Pathway Elucidation

    PubMed Central

    2012-01-01

    The combination of high-resolution LC–MS-based untargeted metabolomics with stable isotope tracing provides a global overview of the cellular fate of precursor metabolites. This methodology enables detection of putative metabolites from biological samples and simultaneous quantification of the pattern and extent of isotope labeling. Labeling of Trypanosoma brucei cell cultures with 50% uniformly 13C-labeled glucose demonstrated incorporation of glucose-derived carbon into 187 of 588 putatively identified metabolites in diverse pathways including carbohydrate, nucleotide, lipid, and amino acid metabolism. Labeling patterns confirmed the metabolic pathways responsible for the biosynthesis of many detected metabolites, and labeling was detected in unexpected metabolites, including two higher sugar phosphates annotated as octulose phosphate and nonulose phosphate. This untargeted approach to stable isotope tracing facilitates the biochemical analysis of known pathways and yields rapid identification of previously unexplored areas of metabolism. PMID:22946681

  20. Plant Water Use and Environmental Stress on Two Opposite Slopes: from Water and Carbon Stable Isotopic Perspective

    NASA Astrophysics Data System (ADS)

    Guan, H.; Xu, X.; Skrzypek, G.; Simmons, C. T.

    2014-12-01

    Climate-soil-vegetation dynamics are among key research focuses in the emerging ecohydrology discipline. Topographic relieves on landscapes provide various hydroclimatic conditions to examine vegetation functions and its responses to climate variation and changes in a short distance. In this study, we investigate ecohydrologic processes on two slopes of contrasting orientation and soil conditions in a native vegetation catchment with mean annual precipitation of 716 mm in South Australia, using water and carbon stable isotopes. Throughfall, soil water, twig water, and groundwater stable isotopes were measured and integrated into an isotope incorporated soil-plant-atmosphere model to examine different plant water use patterns on two slopes with different environmental conditions. The focuses are on how ecosystems on the two slopes receive, store, and use soil moisture in different manners. On these two slopes, trees are under different water stresses. Both leaf and soil 13C/12C ratio were measured for the two slopes to examine if δ13C can be used as an water stress indicator in this small catchm